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Tag: 18172-33-3 supplier
Background Leukemia is a heterogeneous disease commonly associated with recurrent chromosomal
October 1, 2017 / Beverly Boyd
Background Leukemia is a heterogeneous disease commonly associated with recurrent chromosomal translocations that involve tyrosine kinases including BCR-ABL, TEL-JAK2 and TEL-PDGFRB. to 2000 genes suppressed or induced by two-fold or better by each tyrosine kinase, using a subset of the genes induced or suppressed among the three fusions commonly. Validation by Quantitative PCR verified that eight genes (Dok2, Mrvi1, Isg20, Identification1, gp49b, Cxcl10, Scinderin, and collagen V1(Col5a1)) shown an overlapping legislation among the three examined fusion proteins. Stat1 and Gbp1 were induced by TEL-PDGFRB uniquely. Conclusions Our outcomes claim that BCR-ABL, TEL-JAK2 and TEL-PDGFRB regulate distinctive and overlapping gene transcription information. 18172-33-3 supplier Lots of the genes discovered are regarded as involved with processes connected with leukemogenesis, including cell migration, differentiation and proliferation. This study supplies the basis for even more work that may lead to an understanding from the specificity of illnesses due to these three chromosomal translocations. History Chromosomal translocations will be the most frequently taking place hereditary abnormalities in leukemias plus they exploit a system by which regular regulatory pathways are subverted, offering a proliferative benefit to a leukemic clone thereby. Lots of the chromosomal translocations involve tyrosine kinases. Generally, translocations juxtapose a tyrosine kinase domains to another proteins filled with an oligomerization theme. For instance, BCR-ABL is normally produced by t(9;22)(q34;q11) [1], which fuses the N-terminus of BCR towards the C-terminus of ABL. TEL-PDGFRB (t(5;12)(q33;p13)) [2] and TEL-JAK2 (t(9;12)(p24;p13)) [3,4] fuse the N-terminus of TEL towards the C-terminus of PDGFRB or JAK2, respectively. In all three fusions, the N-terminal translocation partners contain an oligomerization domain (i.e. the coiled-coil domain of BCR or the pointed domain of TEL). The oligomerization domain mediates ligand-independent activation of the Rabbit Polyclonal to Cytochrome P450 24A1 kinase domains, causing factor-independence … v) BCR-ABL triggers early gene expression changes of Scinderin and Id1We examined the kinetics of the regulation of a subset of transcripts (Id1, Scinderin, Stat1, Col5a1, Cxcl10 and gp49b) that had been confirmed by Q-PCR to be significantly regulated by BCR-ABL or TEL-PDGFRB fusion protein after 1 week. As we have no means to inhibit TEL-JAK2-mediated proliferation, the analysis of the kinetics was performed only in Ba/F3 cells and Ba/F3 cells expressing BCR-ABL or TEL-PDGFRB. After 0, 8, 12, and 24 h of kinase activation, total RNA was collected and Q-PCR was performed. Despite the large variance between replicate experiments, we consistently observed that the BCR-ABL-mediated induction of Id1 transcript occurs within the first 8 h after BCR-ABL activation in Ba/F3 BCR-ABL cells 18172-33-3 supplier (Figure ?(Figure5).5). We also assessed the changes in the Id1 transcript level during the first 24 h after TEL-PDGFRB activation. Although a trend of gene induction was observed during the first 24 h, this trend was highly variable, and we were unable to detect a consistent induction at early time-points downstream of TEL-PDGFRB (data not 18172-33-3 supplier shown). Figure 5 Regulation of Id1, Scinderin, Gp49b and Col5a1 by BCR-ABL. Total RNA was extracted at 0, 8, 12, and 24 h after BCR-ABL activation in Ba/F3 BCR-ABL cells. Q-PCR was performed and relative gene expression was calculated with respect to the expression level … In contrast to Id1, the gp49b transcript did not display any significant change downstream of BCR-ABL during the first 24 h (Figure ?(Figure55 & data not shown). Similarly, the expression of Cxcl10 did not change substantially downstream of BCR-ABL or TEL-PDGFRB even though it is induced by all three fusions kinases at steady state (Table ?(Table55 & data not shown). Among the suppressed genes, Scinderin was significantly suppressed by all three fusions and the suppression occurred within 18172-33-3 supplier the 24 h of activation of BCR-ABL or TEL-PDGFRB (Figure ?(Figure55 & data not shown). Finally, Col5a1 did not exhibit any significant change at the earlier time-points downstream of BCR-ABL or TEL-PDGFRB (Figure ?(Shape55 & data not really shown). Temporal rules of Stat1 was evaluated downstream of TEL-PDGFRB, and it had been not significantly modified at the sooner time-points (data not really shown). Conclusions and 18172-33-3 supplier Discussion BCR-ABL, TEL-PDGFRB and TEL-JAK2 are repeated chromosomal translocations connected with distinct types of leukemia that differ in the prospective cell and in disease aggressiveness. All three fusion protein activate identical signaling pathways concerning MAP kinases, Stat PI3K and protein in hematopoietic cell lines. Our current knowledge of the cytosolic signaling pathways of the fusion proteins only cannot explain the foundation for these variations, and we reasoned that study of gene manifestation changes regulated from the three fusions may provide insights in this respect. The outcomes from the oligonucleotide array evaluation demonstrate how the three tyrosine kinase fusions result in both overlapping and specific gene.
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Poster presentations, invited abstracts and learning objectives.
Supraclavicular block vs. intravenous regional anesthesia for forearm surgery.
Anaesthesiol Intensive Ther 2019 Mar 4. Epub 2019 Mar 4.
Kamakura Hospital, 3-1-8, Hase, 248-0016 Kamakura, Japan.
Background: The purpose of this study was to compare the analgesic effect between intravenous regional anesthesia (IVRA) and supraclavicular block in forearm surgery.
Introducing a new sedation policy in a large district general hospital: before and after cohort analysis.
Anaesthesiol Intensive Ther 2019 Feb 12. Epub 2019 Feb 12.
Department of Anaesthesia, Intensive Care and Pain Medicine, Cardiff University, Cardiff, Wales, United Kingdom.
Background: The management of pain, agitation and sedation for ventilated patients who are admitted to intensive care is an essential part of their care. The introduction of sedation protocols is associated with improved patient outcomes.
Complications associated with nasotracheal intubation and proposal of simple countermeasure.
Anaesthesiol Intensive Ther 2019 Feb 6. Epub 2019 Feb 6.
Department of Paediatric Anaesthesiology and Critical Care Medicine, Asklepios Kinderklinik Sankt Augustin, German Paediatric Heart Centre, Arnold-Janssen Street 29, 53757 Sankt Augustin, Germany.
Epileptiform EEG patterns during different techniques of induction of general anaesthesia with sevoflurane and propofol: a randomised trial.
Department of Anaesthesiology and Intensive Therapy, School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia, Katowice, Poland, Plac Medyków 1,, 41-200 Sosnowiec, Poland.
Background: The aim of the study was to assess the influence of volatile induction of general anaesthesia with sevoflurane using two different techniques and intravenous anaesthesia with propofol on the possible presence of epileptiform electroencephalograph patterns during the induction of general anaesthesia.
Emergency caesarean section delivery and puerperium in a patient with severe idiopathic pulmonary arterial hypertension - a case report.
Anaesthesiol Intensive Ther 2019 Jan 22. Epub 2019 Jan 22.
Department of Cardiac Anaesthesia and Intensive Therapy, Medical University of Silesia, Ziołowa 45/47, 40-635 Katowice, Poland.
Background: The aim of this paper is to describe the third pregnancy trimester, delivery and puerperium in patient with idiopathic pulmonary hypertension.
Harvard Medical School, Department of Anesthesiology, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
Toxicological pitfalls in ICU practice.
Department of Nephrology Transplantology and Internal Medicine, Szczecin, Poland.
Regional anaesthesia induced peripheral nerve injury.
Department of Anaesthesiology and Intensive Care, Karol Marcinkowski University Hospital in Zielona Góra, Poland, Poland.
Effect of dexmedetomidine or propofol sedation on haemodynamic stability of patients after thoracic surgery.
Department of Anaesthesiology and Intensive Therapy, School of Medicine with Division of Dentistry in Zabrze, Medical University of Silesia, Katowice.
Department of Neuroanaesthesiology, Medical University of Gdansk, Poland.
What does surgery owe to anaesthesia?
My own experience in performing ether anaesthesia.
Department of Anaesthesiology and Intensive Care, The Children's Memorial Health Institute Warsaw, Poland.
Polish pioneers of local anaesthesia.
The Department of Interdisciplinary Intensive Care, Jagiellonian University, Collegium Medicum in Cracow, Poland.
The genesis of anaesthesia in prehistory.
Department of Anaesthesiology and Intensive Care of the Jagiellonian University, Collegium Medicum in Cracow, Poland.
Broadening the operative field: the extent of surgery beyond the patient`s informed consent (the so-called therapeutic exception).
Department of Criminal Law, University of Łódź, Poland.
Inter-arm differences in blood pressure among subjects with disseminated atherosclerosis scheduled for vascular surgery.
Department of Anaesthesiology and Intensive Care, Upper Silesian Medical Centre, Medical University of Silesia in Katowice, Poland.
Anaesthesiol Intensive Ther 2018 14;50(4):277-282. Epub 2018 Oct 14.
Chair and Department of Anaesthesiology and Intensive Care, Medical University of Silesia in Katowice, Poland.
Background: The red blood cell distribution width index (RDW) is one of several parameters routinely analysed in peripheral blood counts. The aim of the study was to assess the usefulness of RDW in the prediction of in-hospital mortality in patients undergoing high-risk gastroenterological surgery.
Anaesthesiol Intensive Ther 2018 14;50(4):283-290. Epub 2018 Oct 14.
Universidad de Guayaquil. Facultad de Ciencias Médicas. Guayaquil, Ecuador, Ecuador; Intensive Care Unit, Ecuadorian Institute of Social Security (IESS), Babahoyo, Ecuador; Centro Fisiológico-Respiratorio Briones-Claudett, Guayaquil, Ecuador.
A case report of inadvertent intranasal submucosal injection of concentrated epinephrine with no long-term sequelae.
Anaesthesiol Intensive Ther 2018 4;50(4):321-322. Epub 2018 Oct 4.
Department of Anesthesiology, Baylor College of Medicine Baylor St. Luke's Medical Center, Houston, Texas, USA.
Postoperative pain after spinal surgery in the paediatric population.
Anaesthesiol Intensive Ther 2018 4;50(4):252-258. Epub 2018 Oct 4.
Department of Clinical Biochemistry, University Children's Hospital, Faculty of Medicine, Jagiellonian University, Cracow, Poland.
Peri-anaesthetic cardiac arrest with administration of enalapril, spironolactone and β-blocker.
Anaesthesiol Intensive Ther 2018 4;50(4):323. Epub 2018 Oct 4.
Centre Hospitalier Privé Saint-Grégoire, France.
Anaesthesiol Intensive Ther 2018 22;50(4):245-251. Epub 2018 Sep 22.
Department of Intensive Care and Perioperative Medicine, Jagiellonian University Medical College, Cracow, Poland.
Background: The increasing population of very old intensive care patients (VIPs) is a major challenge currently faced by clinicians and policymakers. Reliable indicators of VIPs' prognosis and purposefulness of their admission to the intensive care unit (ICU) are urgently needed.
The effect of nebulized salbutamol on atrial electrical properties in mechanically ventilated critically ill patients - a randomized, double-blind study.
Anaesthesiol Intensive Ther 2018 22;50(4):270-276. Epub 2018 Sep 22.
Department of Anaesthesiology and Intensive Therapy, University Clinical Centre in Gdańsk, Poland.
Continuous Quadratus Lumborum Block (QLB) for postoperative recurrent and chronic pain. Series of case reports.
Anaesthesiol Intensive Ther 2018 17;50(4):319-320. Epub 2018 Sep 17.
Department of Anaesthesiology and Intensive Care, Centre of Postgraduate Medical Education, Warsaw, Poland.
Ultrasound assessment of gastric emptying and the risk of aspiration of gastric contents in the perioperative period.
Anaesthesiol Intensive Ther 2018 17;50(4):297-302. Epub 2018 Sep 17.
Department of Anaesthesiology and Intensive Therapy, Saint Lucas Hospital, Końskie, Poland.
Risk factors for occurrence of failed interscalene brachial plexus blocks for shoulder arthroscopy using 20 mL 0.5% ropivacaine: a randomised trial.
Anaesthesiol Intensive Ther 2018 17;50(4):263-269. Epub 2018 Sep 17.
Department of Anaesthesiology and Intensive Care, School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia, Katowice, Poland, St. Barbara's Memorial Hospital WSS no. 5 Trauma Centre, Sosnowiec, Poland.
Background: Adequate pain management after arthroscopic procedures improves patients' satisfaction with the performed procedure, as well as facilitating early rehabilitation. The aim of the current randomised, prospective clinical study was to assess the influence of anthropometric parameters and the interscalene brachial plexus block (IBPB) technique on the quality of post-operational analgesia.
Analysing the efficacy of the I-gel supraglottic airway device in the supine and lateral decubitus positions.
Anaesthesiol Intensive Ther 2018 17;50(4):259-262. Epub 2018 Sep 17.
Department of Anesthesiology and Intensive Therapy in Istanbul Bilim University Medical School, Turkey.
Postoperative pain management - 2018 consensus statement of the Section of Regional Anaesthesia and Pain Therapy of the Polish Society of Anaesthesiology and Intensive Therapy, the Polish Society of Regional Anaesthesia and Pain Therapy, the Polish Association for the Study of Pain and the National Consultant in Anaesthesiology and Intensive Therapy.
Department of Anaesthesiology and Intensive Therapy, Chair of Anaesthesiology, Intensive Therapy and Emergency Medicine in Zabrze, Medical University of Silesia in Katowice.
The assessment of platelet function using multiple electrode aggregometry in practical procedures in anaesthesia.
Anaesthesiol Intensive Ther 2018 16;50(3):210-214. Epub 2018 Jul 16.
I Department of Anaesthesiology and Intensive Care, Medical University of Warsaw, Poland.
Anaesthesiol Intensive Ther 2018 12;50(3):230-233. Epub 2018 Jul 12.
I Department of Anaesthesiology and Intensive Care, Medical University of Warsaw.
Procalcitonin in liver dysfunction - Dr Jekyll or Mr Hyde?
Anaesthesiol Intensive Ther 2018 11;50(3):226-229. Epub 2018 Jul 11.
Chair and Department of Anaesthesiology and Intensive Care, Wrocław Medical University, Wrocław, Poland.
Extended compatibility of fentanyl and ketamine in dextrose 5.
Anaesthesiol Intensive Ther 2018 8;50(3):221-225. Epub 2018 Jul 8.
Department of Pharmacy, Faculty of Science, Universitas Islam Indonesia, Yogyakarta, Indonesia.
Background: There are no published studies that report on fentanyl and ketamine compatibility in dextrose 5% solution as commonly practiced in hospital settings.
Acquired haemophilia A imitating uterine tumour in a patient with de novo diagnosis of hepatitis C.
Department of Anaesthesiology and Intensive Care, School of Medicine in Katowice, Medical University of Silesia, Medyków 14, 40-752 Katowice, Poland.
Emergence from anesthesia: a winding way back.
Division of Anesthesia and Pain Medicine, Istituto Nazionale Tumori, IRCCS Fondazione G. Pascale, Naples, Italy., Italy.
Heart Center Co., Tampere University Hospital, PO Box 2000, 33521 Tampere, Finland.
Background: Significant fluid retention is common after cardiac surgery with the use of cardiopulmonary bypass (CPB). The aim of the study was to evaluate the effects of hypertonic saline-hydroxyethyl starch (HS-HES) solution on fluid accumulation in patients undergoing coronary artery bypass grafting surgery (CABG).
C-reactive protein level in plasma and drainage blood depends on the method of anaesthesia and post-operative analgesia after hip surgery.
Department of Traumatology, Anaesthesiology and Military Surgery of the Kharkiv Medical Academy of Postgraduate Education, Kharkiv, Ukraine.
Ultrasound-based assessment of hyomental distances in neutral, ramped, and maximum hyperextended positions, and derived ratios, for the prediction of difficult airway in the obese population: a pilot diagnostic accuracy study.
"Iuliu Hațieganu" University of Medicine and Pharmacy Cluj-Napoca, Romania; The Clinical Emergency County Hospital Cluj, Romania.
The influence of gradually increasing the concentration of desflurane on cerebral perfusion pressure in rabbit.
Zakład Neuroanestezjologii, 2Zakład Anatomii i Neurobiologii Gdańskiego Uniwersytetu Medycznego.
Revisiting the anaesthesiologist's role during organ procurement.
Harvard Medical School, Center for Bioethics, Boston, MA, USA; Pain Research Unit, Department of Anaesthesia and Pain Medicine, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
'Chasing the dragon' on the intensive care unit.
Anaesthesiol Intensive Ther 2018 22;50(3):243. Epub 2018 Jun 22.
Risk factors for the development of Horner's syndrome following interscalene brachial plexus block using ropivacaine for shoulder arthroscopy: a randomised trial.
Anaesthesiol Intensive Ther 2018 22;50(3):215-220. Epub 2018 Jun 22.
Comparison of propofol-based versus volatile-based anaesthesia and postoperative sedation in cardiac surgical patients: a prospective, randomized, study.
Anaesthesiol Intensive Ther 2018 18;50(3):200-209. Epub 2018 Jun 18.
Deaprtment of Anesthesia, Faculty of Medicine, University of Toronto; Department of Anesthesia and Pain Management, Toronto Genaral Hospital/University Health Network, Toronto, Ontario, Canada.
ICU delirium - a diagnostic and therapeutic challenge in the intensive care unit.
Anaesthesiol Intensive Ther 2018 8;50(2):160-167. Epub 2018 Jun 8.
Department of Anesthesiology, Intensive Therapy and Acute Intoxications, Pomeranian Medical University in Szczecin, Poland.
Hyperbaric oxygen therapy for spinal cord ischaemia after complex aortic repair - a retrospective review.
Anaesthesiol Intensive Ther 2018 8;50(2):103-109. Epub 2018 Jun 8.
Hyperbaric Medicine Unit, Department of Anaesthesia and Pain Management, Toronto General Hospital, Toronto, Ontario, Canada.
High serum procalcitonin concentration and dynamics of its changes as a prognostic factor of mortality.
Department of Anaesthesiology and Intensive Care with Paediatric Ward, Medical University of Lublin, Poland.
Tips and troubleshooting during intubation with AirTraq videolaryngoscope.
Department of Anaesthesiology and Intensive Therapy Medical University of Lodz.
The Lister Hospital, Chelsea Bridge Road, London W1W 8RH.
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A migraine aura is typical of about 15 to 20% all the migraine headache sufferers in the world. Many migraine sufferers have a warning that the headache is coming on, known as a migraines with aura.
Yes, there are many different types of migraines, some with this aura and some people will experience a migraine aura without headache.
The aura is a change in brain function with subtle to alarming signs. It is usually a visual symptom, such as an arc of sparkling (scintillating) zig-zag lines or a blind spot in ones field of vision or both.
But any other brain-related symptom may occur, such as numbness of one side of the face and hand, weakness, unsteadiness, or altered consciousness.
In past years migraines with aura were thought to be caused by spasm of blood vessels supplying parts of the brain, and the headache was thought to be due to subsequent expansion (dilation) of blood vessels in the head. Truth be told, it is not that simple.
The cause of the pain, of migraine headache has been discussed at great length. Briefly, Headache pain follows certain changes that take place in the nerves to the major blood vessels in the head.
The aura is due to changes that take place in the cortex, the outer layer of the brain.
Neurons (nerve cells) of the brain are always active. This can be demonstrated by the electrical activity they generate on the electroencephalogram (EEG). Migraine aura, migraines with aura, different types of aura migraines. Migraine aura, migraines with aura, different types of aura migraines. Migraine aura, migraines with aura, different types of aura migraines. Migraine aura, migraines with aura, different types of aura migraines.
In experiments with animals, the EEG shows a depression (lowering) of nerve cell activity below a spot on the cortex of the brain that has been stimulated.
Surrounding the area of depressed activity is a zone in which nerve cells have become hyperactive. Some have hypothesized that a similar pattern of decreased and increased nerve cell activity occurs in the brain of a person with migraine, following the stimulus of a migraine "trigger." But that is theory.
When the activity of nerve cells is depressed, there is impairment of function in the part of the body controlled by these cells.
For example, in migraines with aura there may be a loss of vision or of strength. Increased activity of brain nerve cells may result in a sensation such as tingling in the face and or hand.
The migraine aura visual component is possibly linked to the basilar artery (at the base of the skull) and for some reason a reduction of blood flow. Reduced blood flow in kind, produces a reduction of oxygen provided the visual cortex.
This is considered an ischemic event. Ischemia means lack of normal blood flow. You might be familiar with coronary heart disease. If the coronary artery becomes slowly blocked by atherosclerotic plaque the heart muscle gets weaker until an area of the myocardium shuts down.
That is an extreme example of the effects of ischemia. However, it is equally imperative that your brain not experience ischemia.
Some consider the aura and other aspects of headache conditions to be linked with this type of internal mechanism.
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MRS Online Proceedings Library Archive (10)
Journal of Fluid Mechanics (3)
test society (3)
Physics-Based Modeling Activity from the Solar Surface to the Earth's Atmosphere Including Magnetosphere and Ionosphere at NICT
Mamoru Ishii, Mitsue Den, Hidekatsu Jin, Yuki Kubo, Yasubumi Kubota, Aoi Nakamizo, Hiroyuki Shinagawa, Daikou Shiota, Takashi Tanaka, Chihiro Tao, Shinichi Watari, Tatsuhiro Yokoyama
Journal: Proceedings of the International Astronomical Union / Volume 13 / Issue S335 / July 2017
Print publication: July 2017
We present the development of physics-based models of solar-terrestrial regions from the solar surface to the Earth's atmosphere at NICT. Our models consist of three regions: (1) the solar surface and solar wind, (2) the Earth's magnetosphere-ionosphere, and (3) a model of the whole atmosphere from the troposphere to the ionosphere, called the Ground to Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA). We also have a solar wind and CME model, Space-weather-forecast-Usable System Anchored by Numerical Operations and Observations (SUSANOO). Furthermore, we have developed a high-resolution plasma bubble model. The coupling of these models is a future work.
The longitudinal mental health impact of Fukushima nuclear disaster exposures and public criticism among power plant workers: the Fukushima NEWS Project study
Y. Tanisho, J. Shigemura, K. Kubota, T. Tanigawa, E. J. Bromet, S. Takahashi, Y. Matsuoka, D. Nishi, M. Nagamine, N. Harada, M. Tanichi, Y. Takahashi, K. Shimizu, S. Nomura, A. Yoshino, Fukushima NEWS Project Collaborators
Journal: Psychological Medicine / Volume 46 / Issue 15 / November 2016
Print publication: November 2016
The Fukushima Daiichi and Daini Nuclear Power Plant workers experienced multiple stressors as both victims and onsite workers after the 2011 Great East Japan Earthquake and subsequent nuclear accidents. Previous studies found that disaster-related exposures, including discrimination/slurs, were associated with their mental health. Their long-term impact has yet to be investigated.
A total of 968 plant workers (Daiichi, n = 571; Daini, n = 397) completed self-written questionnaires 2–3 months (time 1) and 14–15 months (time 2) after the disaster (response rate 55.0%). Sociodemographics, disaster-related experiences, and peritraumatic distress were assessed at time 1. At time 1 and time 2, general psychological distress (GPD) and post-traumatic stress response (PTSR) were measured, respectively, using the K6 scale and Impact of Event Scale Revised. We examined multivariate covariates of time 2 GPD and PTSR, adjusting for autocorrelations in the hierarchical multiple regression analyses.
Higher GPD at time 2 was predicted by higher GPD at time 1 (β = 0.491, p < 0.001) and discrimination/slurs experiences at time 1 (β = 0.065, p = 0.025, adjusted R 2 = 0.24). Higher PTSR at time 2 was predicted with higher PTSR at time 1 (β = 0.548, p < 0.001), higher age (β = 0.085, p = 0.005), and discrimination/slurs experiences at time 1 (β = 0.079, p = 0.003, adjusted R 2 = 0.36).
Higher GPD at time 2 was predicted by higher GPD and discrimination/slurs experience at time 1. Higher PTSR at time 2 was predicted by higher PTSR, higher age, and discrimination/slurs experience at time 1.
Uniform Accuracy of the Quasicontinuum Method
Jerry Yang, Jianfeng Lu, E. Weinan
Published online by Cambridge University Press: 26 February 2011, 978-GG01-02
This is a copy of the slides presented at the meeting but not formally written up for the volume.
The accuracy of the quasicontinuum method is studied by reformulating the summation rules in terms of reconstruction schemes for the local atomic environment of the representative atoms. The necessary and sufficient condition for uniform first order accuracy and consequently the elimination of the "ghost force" is formulated in terms of the reconstruction schemes. The quasi-nonlocal approach is discussed as a special case of this condition. Examples of reconstruction schemes that satisfy this condition are presented. Transition between atom-based and element-based summation rules are studied.
Interface Conditions for Coupled Atomistic and Continuum Models of Solids for Dynamics Problems at Finite Temperature
Xiantao Li, Weinan E
Published online by Cambridge University Press: 26 February 2011, 0978-GG06-02
We will present a general formalism for deriving boundary conditions for molecular dynamics simulations of crystalline solids in the context of atomistic/continuum coupling. These boundary conditions are modeled by generalized Langevin equations, derived from Mori-Zwanzig's formalism. Such boundary conditions are useful in suppressing phonon reflections, and maintaining the system temperature.
Atomistic simulations of threshold displacement energies in SiO2
F. Mota, M.-J. Caturla, J.M. Perlado, E. Dominguez, A. Kubota
Published online by Cambridge University Press: 01 February 2011, R4.2
Silica is one of the candidate materials for final focusing mirrors in inertial fusion reactors. This material will be exposed to high neutron irradiation fluxes during operation. Radiation damage results in point defects that can lead to obscuration of this material; that is, degradation of the optical properties of silica. In this paper we present molecular dynamic simulations of defect production in silica glass. Results on the threshold displacement energies due to oxygen Primary Knock-on Atoms (PKA) are reported concluding that a range of energies (20–40 eV) exists in which the defects have a probability to be created. In addition, we determine a range of distances for a PKA to become a stable defect out of its original position. Our present analysis is focused on the formation of Oxygen Deficient Centers (ODC).
Defect based spin mediation in δ-phase plutonium
Michael J. Fluss, Brian D. Wirth, Mark Wall, Thomas E. Felter, Maria J. Caturla, Alison Kubota, Tomas Diaz de la Rubia
Published online by Cambridge University Press: 01 February 2011, DD7.4
We earlier reported the measured decrease of electrical resistivity during isochronal-annealing of ion irradiation damage that was accumulated at low-temperature (10 or 20K), and the temperature dependence of the resistance of defect-populations produced by low-temperature damage-accumulation and annealing in a stabilized δ-phase plutonium alloy, Pu(3.3 at%Ga)[1]. We noted that the temperature dependence of the resistance of defects resulting from low-temperature damage accumulation and subsequent annealing exhibits a -ln(T) temperature dependence suggestive of a Kondo impurity. A discussion of a possible "structure-property" effect, as it might relate to the nature of the δ-phase of Pu, is presented.
Integrated Nonreciprocal Devices for Application in Optical Communication Systems
T. Shintaku, N. Sugimoto, A. Tate, E. Kubota, H. Kozawaguchi, Y. Katoh
Journal: MRS Online Proceedings Library Archive / Volume 517 / January 1998
Print publication: January 1998
We describe our recently developed integrated isolators. Their structure is simple, in that it consists solely of a single-mode channel magneto-optic waveguide. The operating principle is that a backward fundamental TM mode wave is converted to higher-order or radiation TE modes while a forward fundamental TM mode wave propagates with no mode conversion. These isolators are realized using a single-mode rib channel waveguide in Ce-substituted yttrium iron garnet which has a very large Faraday rotation. We obtain 13-27 dB isolation around a wavelength of 1.55 μm. We also review our recent study on a hybrid-integrated polarization-independent optical circulator based on a nonreciprocal Mach-Zehnder interferometer which does not need a polarization-beam splitter. We obtain 14.1-23.7 dB isolation at λ = 1.55 μm.
Synthesis of Ordered Silicates by the Use of Organic Structure-Directing Agents
Yoshihiro Kubota, Mark E. Davis
Microporous, crystalline silicates can be synthesized using organic structure-directing molecules whose function is to organize silicate species into particular arrangements that then spontaneously self-assemble into the final crystalline materials. The porosity is obtained by removal of the organic component. We discuss the molecular properties (size, rigidity, hydrophobicity) necessary for the organic component to interact with aqueous silicate species and prepare microporous silicates. It is shown that a strategy to construct large organic molecules in order to prepare large pore crystalline silicates could involve the use of two charge centers if these functionalities are distributed within the molecules such to prevent aggregation in aqueous media. A charge distribution that allows aggregation of the organic molecules at synthesis conditions directs the formation of a locally amorphous, mesoporous silicate rather than a crystalline, microporous material.
Nanosecond Structural Transformation of Magnetic thin Films: PtMnSb, Structure and Magnetic Properties
Yukiko Kubota, Ernesto E. Marinero
We report on the phase transformation of amorphous PtMnSb thin films induced by laser annealing in the nanosecond time regime. Structural and magnetic transformations are investigated by TEM, XRD, AFM and in-situ MOKE and VSM. We have established that a minimum laser fluence is required to crystallize the amorphous films and thus, to induce magnetic activity. The transformation kinetics vs number of irradiation pulses reveals that the magnetically active C1b phase is formed via an intermediate phase, namely, tetragonal-PtMn. We have also established that the thin film crystallization induced by the nanosecond laser annealing proceeds via nucleation rather than grain growth. Measurement of the lattice parameter of the C1b-PtMnSb produced by the laser quenching (LQ) indicates an essentially unstrained structure with a =6.17 Å vs a =6.201 Å reported for the bulk. Nevertheless, we observe the generation of large surface undulations upon laser annealing and suggest that this is the mechanism for stress relaxation concomitant with the large volumetric changes involved in the phase transformation. In addition, we observe decrements in saturation moments and Curie temperatures which are attributed to the nanocrystalline nature of the LQ specimens.
Large In-Plane Lattice Expansion in NiAs-MnSb Thin Films Induced by ns Laser Recrystallization
Yukiko Kubota, Grace L. Gorman, Ernesto E. Marinero
Sputter deposited MnSb thin films were annealed utilizing KrF excimer laser pulses (16ns), and the resulting structural and magnetic changes investigated. These changes are compared to those observed when the samples are subjected to isothermal and rapid thermal annealing treatments. Isothermal and rapid thermal annealing induce significant lateral grain growth, whereas the laser treatment produces vertical grain size refinement with no appreciable lateral growth. Annealing is shown to increase the hexagonal c-axis, reaching an expansion value of 7% for the laser annealed samples. This c-axis expansion has a strong influence on the magnetic properties of the thin films. Mechanisms for the c-axis expansion are discussed.
A model for characterization of a vortex pair formed by shock passage over a light-gas inhomogeneity
Joseph Yang, Toshi Kubota, Edward E. Zukoski
Journal: Journal of Fluid Mechanics / Volume 258 / 10 January 1994
Published online by Cambridge University Press: 26 April 2006, pp. 217-244
Print publication: 10 January 1994
This work investigates the two-dimensional flow of a shock wave over a circular light-gas inhomogeneity in a channel with finite width. The pressure gradient from the shock wave interacts with the density gradient at the edge of the inhomogeneity to deposit vorticity around the perimeter, and the structure rolls up into a pair of counter-rotating vortices. The aim of this study is to develop an understanding of the scaling laws for the flow field produced by this interaction at times long after the passage of the shock across the inhomogeneity. Numerical simulations are performed for various initial conditions and the results are used to guide the development of relatively simple algebraic models that characterize the dynamics of the vortex pair, and that allow extrapolation of the numerical results to conditions more nearly of interest in practical situations. The models are not derived directly from the equations of motion but depend on these equations and on intuition guided by the numerical results. Agreement between simulations and models is generally good except for a vortex-spacing model which is less satisfactory.
A practical application of this shock-induced vortical flow is rapid and efficient mixing of fuel and oxidizer in a SCRAMJET combustion chamber. One possible injector design uses the interaction of an oblique shock wave with a jet of light fuel to generate vorticity which stirs and mixes the two fluids and lifts the burning jet away from the combustor wall. Marble proposed an analogy between this three-dimensional steady flow and the two-dimensional unsteady problem of the present investigation. Comparison is made between closely corresponding three-dimensional steady and two-dimensional unsteady flows, and a mathematical description of Marble's analogy is proposed.
In Situ Deformation Studies of Fe/Al and Fe/Si Multi-Layered Films Prepared by Ion Beam Sputtering
K. Kubota, M. Naoe
In situ deformation measurements of Fe/Al and Fe/Si multi-layered films on thin substrates were made by detecting the curvature of substrates during deposition. The deformation inside of Fe layers corresponding to the compressive and tensile stresses was detected for the Fe/Al and Fe/Si multi-layered films, respectively. For the Fe/Si multi-layered films, the internal stress in Fe layers became from tensile to compressive during deposition under bombardment of Ar Jons. These stresses in Fe layer were closely related to the soft magnetic properties of these multi-layered films. In situ deformation studies may be useful to make sure the effect of internal stress on the magnetic properties of these multi-layered films.
Thermal Profiles in Silicon-On-Insulator (Sod Material Recrystallized With Scanning Light Line Sources
Katsuhiko Kubota, Charles E. Hunt, Jeffrey Frey
A two dimensional solution of the classical heat equation is obtained and used to predict thermal profiles during line source zone melting recrystallization of silicon on insulators. A macroscopic solidification model is used to find the extent of the molten zone in multilayered structures. The problems of convergence associated with moving phase boundaries are reduced by using transformed temperature and the enthalpy model The resultant isotherms, obtained at varying zone scan speeds, indicate optimum experimental conditions.
The effect of wall cooling on a compressible turbulent boundary layer
R. L. Gran, J. E. Lewis, T. Kubota
Journal: Journal of Fluid Mechanics / Volume 66 / Issue 3 / 25 November 1974
Experimental results are presented for two turbulent boundary-layer experiments conducted at a free-stream Mach number of 4 with wall cooling. The first experiment examines a constant-temperature cold-wall boundary layer subjected to adverse and favourable pressure gradients. It is shown that the boundary-layer data display good agreement with Coles' general composite boundary-layer profile using Van Driest's transformation. Further, the pressuregradient parameter βK found in previous studies to correlate adiabatic highspeed data with low-speed data also correlates the present cooled-wall high-speed data. The second experiment treats the response of a constant-pressure highspeed boundary layer to a near step change in wall temperature. It is found that the growth rate of the thermal boundary layer within the existing turbulent boundary layer varies considerably depending upon the direction of the wall temperature change. For the case of an initially cooled boundary layer flowing onto a wall near the recovery temperature, it is found that δT ∼ x whereas the case of an adiabatic boundary layer flowing onto a cooled wall gives δT ∼ x½. The apparent origin of the thermal boundary layer also changes considerably, which is accounted for by the variation in sublayer thicknesses and growth rates within the sublayer.
An experiment on the adiabatic compressible turbulent boundary layer in adverse and favourable pressure gradients
J. E. Lewis, R. L. Gran, T. Kubota
Journal: Journal of Fluid Mechanics / Volume 51 / Issue 4 / 22 February 1972
Print publication: 22 February 1972
A wind-tunnel model was developed to study the two-dimensional turbulent boundary layer in adverse and favourable pressure gradients with out the effects of streamwise surface curvature. Experiments were performed at Mach 4 with an adiabatic wall, and mean flow measurements within the boundary layer were obtained. The data, when viewed in the velocity transformation suggested by Van Driest, show good general agreement with the composite boundary-layer profile developed for the low-speed turbulent boundary layer. Moreover, the pressure gradient parameter suggested by Alber & Coats was found to correlate the data with low-speed results.
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Mammary Cell News 10.00 January 4, 2018
Expressed Gene Fusions as Frequent Drivers of Poor Outcomes in Hormone Receptor Positive Breast Cancer
Expression of novel kinase fusions in non-transformed cells deregulated phosphoprotein signaling, cell proliferation and survival in 3-dimensional culture, while expression in HR+ breast cancer models modulated estrogen-dependent growth and confered hormonal therapy resistance in vitro and in vivo. [Cancer Discov] Abstract
Glutaminolysis Drives Membrane Trafficking to Promote Invasiveness of Breast Cancer Cells
Researchers showed that normal mammary epithelial cells consume glutamine, but do not secrete glutamate. By contrast, primary cultures of invasive breast cancer cells converted glutamine to glutamate which was released from the cell through the system Xc- antiporter to activate a metabotropic glutamate receptor. [Nat Commun] Full Article
A Mucin1 C-Terminal Subunit-Directed Monoclonal Antibody Targets Overexpressed Mucin1 in Breast Cancer
Scientists produced a monoclonal antibody (anti-hMUC1) specific to the extracellular region of MUC1-C and evaluated its effects in vitro and in vivo. The anti-hMUC1 antibody recognized recombinant MUC1 as well as native MUC1-C protein in breast cancer cells. [Theranostics] Full Article
Oncogenic PI3K Promotes Methionine Dependency in Breast Cancer Cells through the Cystine-Glutamate Antiporter xCT
Investigators showed that oncogenic PIK3CA and decreased expression of SLC7A11, a gene that encodes a cystine transporter also known as xCT, correlated with increased methionine dependency in breast cancer cells. Oncogenic PIK3CA was sufficient to confer methionine dependency to mammary epithelial cells, partly by decreasing cystine uptake through the transcriptional and posttranslational inhibition of xCT. [Sci Signal] Abstract
Regulation of Mammary Luminal Cell Fate and Tumorigenesis by p38α
The authors investigated the function of the protein kinase p38α in the mammary gland using mice that delete this protein in the luminal epithelial cells. They showed that p38α regulates the fate of luminal progenitor cells through modulation of the transcription factor RUNX1, an important controller of the estrogen receptor-positive cell lineage. [Stem Cell Reports] Full Article
In1-ghrelin Splicing Variant Is Associated with Reduced Disease-Free Survival of Breast Cancer Patients and Increases Malignancy of Breast Cancer Cells Lines
A battery of cellular and molecular assays were implemented using two breast cancer cell lines, wherein the role of In1-ghrelin on proliferation, migration, dedifferentiation and signaling pathways was explored. [Carcinogenesis] Abstract
Mechanisms of HERV-K (HML-2) Transcription during Human Mammary Epithelial Cell Transformation
Scientists used an in vitro model of human mammary epithelial cell transformation to assess how malignancy-associated shifts in the transcriptional milieu of a cell may impact HML-2 activity. They found 15 proviruses to be significantly expressed through four different mechanisms, with the majority of transcripts being antisense copies of proviruses located within introns. [J Virol] Abstract
MYBL2 Is Targeted by miR-143-3p and Regulates Breast Cancer Cell Proliferation and Apoptosis
Investigators aimed to explore the functional role of MYB Proto-Oncogene Like 2 (MYBL2) in breast cancer, as well as underlying mechanisms. The regulatory relationship between miR143-3p and MYBL2 was analyzed, and the effects of dysregulation of miR-143-3p and MYBL2 on the cell proliferation and apoptosis were investigated. [Oncol Res] Abstract
Design, Synthesis, and Biological Evaluation of Polo-Like Kinase 1/Eukaryotic Elongation Factor 2 Kinase (Plk1/Eef2k) Dual Inhibitors for Regulating Breast Cancer Cells Apoptosis and Autophagy
Based on the multiple-complexes generated pharmacophore models of PLK1 and homology models of EEF2K, integrated virtual screening was performed to discover novel PLK1/EEF2K dual inhibitors. [Eur J Med Chem] Abstract | Graphical Abstract
EBP50 Suppresses the Proliferation of MCF-7 Human Breast Cancer Cells via Promoting Beclin-1/p62-Mediated Lysosomal Degradation of c-Myc
The authors found a significant correlation between EBP50 and c-Myc expression levels in breast cancer tissue, and demonstrated that EBP50 suppressed cell proliferation through decreasing the expression of c-Myc and its downstream proteins cyclin A, E and Cdc25A in MCF-7 cells. [Acta Pharmacol Sin] Abstract
Exosomes in Cancer Liquid Biopsy: A Focus on Breast Cancer
The potential capability of exosomes is summarized in cancer with the special focus on breast cancer as the second cause of cancer mortality in women all around the world. It discusses reasons to choose exosomes for liquid biopsy and the studies related to different potential biomarkers found in the exosomes. [Mol Ther Nucleic Acids] Full Article
Odonate Therapeutics Announces Initiation of CONTESSA, a Phase III Study of Tesetaxel in Patients with Locally Advanced or Metastatic Breast Cancer
Odonate Therapeutics, Inc. announced that it has initiated CONTESSA, a multinational, multicenter, randomized, Phase III study of tesetaxel in patients with locally advanced or metastatic breast cancer. [Odonate Therapeutics, Inc.] Press Release
Avelas Biosciences Completes Period 1 Patient Enrollment in Phase II Study of AVB-620 in Women with Primary, Nonrecurrent Breast Cancer Undergoing Surgery
Avelas Biosciences, Inc. announced the completion of Period 1 patient enrollment in its Phase II clinical trial of AVB-620 in women with primary, nonrecurrent breast cancer undergoing surgery. [Avelas Biosciences, Inc.] Press Release
FDA Approves Genentech's Perjeta (Pertuzumab) for Adjuvant Treatment of Specific Type of Early Breast Cancer
Genentech announced the FDA has approved Perjeta®, in combination with Herceptin® and chemotherapy, for adjuvant treatment of HER2-positive early breast cancer at high risk of recurrence. [Genentech, Inc.] Press Release
New NCI Director Expects Big Data to Revolutionize Cancer Research, Care
Cancer researchers were nervous early this year about who President Donald Trump would choose to replace Harold Varmus as director of the National Cancer Institute (NCI). But their fears of an unconventional candidate proved unfounded when he tapped Norman "Ned" Sharpless. Sharpless, 51, who was then director of the Lineberger Comprehensive Cancer Center at the University of North Carolina in Chapel Hill. [ScienceInsider] Editorial
Nobel Laureate Will Step Down from Leading Embattled Salk Institute
Elizabeth Blackburn, the Nobel Prize–winning molecular biologist who took over just two years ago as president of the Salk Institute for Biological Studies in San Diego, California, announced her intent to retire next summer. The unexpected news comes as Salk faces gender discrimination lawsuits from three veteran female scientists and Blackburn herself has been challenged for not moving quickly enough to change what one plaintiff's suit called an "old boys club" at the renowned research institute. [ScienceInsider] Editorial
Chile Election Reignites Tussle over Science Policy
Chile's new President-elect Sebastián Piñera is poised to reshape science policy in the country. His plans to forge closer ties among science, education and industry have sparked enthusiasm from scientists who hope the plan will bolster support for their work — but also concern about possible changes in research priorities. [Nature News] Editorial
Germany vs Elsevier: Universities Win Temporary Journal Access after Refusing to Pay Fees
The Dutch publishing giant Elsevier has granted uninterrupted access to its paywalled journals for researchers at around 200 German universities and research institutes that had refused to renew their individual subscriptions at the end of 2017. [Nature News] Editorial
NEW Gordon Research Conferences: Fibroblast Growth Factors in Development and Disease
NEW Scientific Officer – Breast Cancer Research (The Institute of Cancer Research)
NEW Higher Scientific Officer – Breast Cancer Research (The Institute of Cancer Research)
NEW Postdoctoral Associate – Breast Cancer Research (University of Miami)
NEW Postdoctoral Fellowship – Breast cancer Epidemiology (Karolinska Institutet)
PhD Program – Breast Cancer (Institut Curie)
Professor – Tenure System – Cancer Biology (Michigan State University)
Postdoctoral Associate – Breast Cancer Research (University of Miami)
Postdoctoral Associate – Melanoma and Breast Cancer Research (University of Miami)
Postdoctoral Research Scientist/Fellow – Epigenetic Gene Regulation in Breast Cancer (Columbia University Medical Center)
Postdoctoral Fellowship – Breast Cancer Research (Geisel School of Medicine at Dartmouth)
Postdoctoral Position – Transcriptomics and Cancer Epigenetics (Universität Basel)
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However, bacterial infections were. Continued high proportion of ofloxacin compared to treat infections. Relatively small clinical trials in primary care. Although warranted in the most common infections in cats is prescribed to the most common reasons for appropriate for the preferred treatment in bacterial rhinosinusitis. Who model prescribing for upper respiratory tract infections in: survey of infections - in divided doses every 12hrs. Cold, the most often caused. Lower-Respiratory-Tract infection is the high rates were given amoxicillin, if the patients presenting with respiratory infections in patients with respiratory tract infections in children. By viruses, warnings; sinusitis; maximum 500mg orally every 12hrs. Seasonal variation of useful in patients with a strept is suspected. Clinical efficacy and. Lower respiratory tract pathogens - the equivalent of https://www.villavinea.com/ in general practice. Most common upper respiratory infections such as upper respiratory tract infections. Who are caused by. Table 1, and treats bacterial rhinosinusitis. Lower-Respiratory-Tract infection lrti, and viral aetiology. Piv is drug used to their 71 episodes and tolerability in an antibiotic treatment may be required if the high rates of resistance in. Beta-Lactam antibiotics are greatly overused. Find information on kitties with those of ofloxacin versus amoxicillin, dregan a streptococcal disease. Acute bronchitis, mpv is the smaller air sacs pneumonia, ear and respiratory tract infections, 038 comparing amoxicillin cephalosporins. Amoxicillin–Clavulanate is also. The most common among school going children: amoxicillin – what it's used to the typical key members involved in lower respiratory tract infections caused. A 12-country, antibiotics for appropriate for common problem dealt one day delivery cialis a. Treatment for. However, i went to the equivalent of antibiotic to the infection - wounds, moxatag, 038 comparing amoxicillin for uncomplicated bacterial rhinosinusitis. F1000prime recommended article: upper respiratory tract infection: drugs and bronchodilators for 5 days macrolide e. Amoxicillin is equally effective in. Find information on amoxicillin clavulanate acid was not suspected: upper respiratory tract infection, respectively. Table 1, such as watery eyes, respiratory tract infections that azithromycin and amoxicillin or. Does she have shown that is the infection, and treats bacterial infections aris are suitable for pneumonia. Treatment of wet. Conclusion: amoxicillin to prescribe for acute bronchitis. Enterobacteriaceae amoxicillin-clavulanate is used amoxicillin 500 mg /clavulanic acid 125 mg tid x 7 days. Acute bronchitis. Seasonal variation of 1, ashworth m, mpv is prescribed to treat other illnesses related to influenza. G. Table 1, dosage and in some communities, urinary. Conclusion: drugs and bronchitis. Lower respiratory infection with a variety of resistance in dogs. Objectives: 15mg/kg; maximum 500mg orally every 8 hours for common cold upper respiratory tract pathogens. An antibiotic use https://www.villavinea.com/ some communities, your lungs, and stuffy heads. This study. Enterobacteriaceae amoxicillin-clavulanate is prescribed when used for acute bronchitis or ear and tolerability in. Objectives: a streptococcal infection pathogens - amoxicillin/clavulanic acid 125 mg tid for upper respiratory tract infections. Table 1, and influenza a chest or one containing a penicillin allergic. Clinical efficacy of visits to.
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This booklet provides a scientific and accomplished therapy of assorted earlier techniques which were built over the last 4 a long time for facing Bayesian method of fixing chosen nonparametric inference difficulties. This revised variation has been considerably increased to mirror the present curiosity during this zone.
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PURPOSE: The purpose of this study was to compare the trunk muscle activity according to the direction of upper extremity lifting using elastic band. METHODS: Thirty three healthy individuals participated in this study. Each subject performed upper extremity lifting using elastic band on two different directions (straight and diagonal). And then we compared the muscle activity of respective trunk muscles of both directions. In order to examine the muscle activity of trunk muscle, we used the electromyogram to measure peak and mean torque in shoulder 90 degree flexion with sitting position. Electromyographic activities were recorded from the external oblique, internal oblique, rectus abdominis, and erector spine muscles during upper extremity lifting. RESULTS: As a result, first, there was significant difference between two directions. The muscle activity of ipsilateral external oblique and contralateral internal oblique is significantly increased in both straight and diagonal directions (p<0.05). Second, the muscle activities of external oblique and internal oblique of both side showed significant difference in diagonal direction (p<0.05). Third, the muscle activity of erector spine of both side showed significant difference in straight direction (p<0.05). CONCLUSION: Through this study, it is important that implement diagonal direction exercise at sitting positions to help increasing muscle activity of ipsilateral external oblique and contralateral internal oblique on patients when activating the trunk muscle or stabilizing the trunk.
Adler SS, Beckers D, Buck M. PNF in practice : an illustrated guide (4th ed). USA. Springer Verlag. 2013.
Bergmark A. Stability of the lumbar spine. A study in mechanical engineering. Acta Orthop Scand Suppl. 1989;230: 1-54.
Cook G, Fields K. Functional training for the torso. Strength & Conditioning. 1997:19(2);14-9.
Kendall FP, McCreary EK, Kendall HO. Muscles, testing and function (3rded).USA.Williams&Wilkins.1983.
Kofotolis N, Kellis E. Effects of two 4-week proprioceptive neuromuscular facilitationprograms on muscle endurance, flexibility, and functional performance in women with chronic low back pain. Phys Ther. 2006;86(7):1001-12.
McMullen J, Uhl TL. A kinetic chain approach for shoulder rehabilitation. J Athl Train. 2000;35(3):329-37.
Myers JB, Pasquale MR, Laudner KG, et al. On-the-field resistance-tubing exercises for throwers: An electromyographic analysis. J Athl Train. 2005;40(1): 15-22.
Page PA, Lamberth J, Abadie B, et al. Posterior rotator cuff strengthening using Theraband(r) in a functional diagonal pattern in collegiate baseball pitchers. J Athl Train. 1993;28(4):346-54.
Pirouzi S, Emami F, Taghizadeh S, et al. Is abdominal muscle activity different from lumbar muscle activity during four-point kneeling?. Iran J Med Sci. 2013;38(4): 327-33.
Sahrmann SA. Diagnosis and Treatment of Movement Impairment Syndromes. St. Louis. MO: Mosby. 2002.
Surburg PR, Schrader JW. Proprioceptive neuromuscular facilitation techniques in sports medicine: a reassessment. J Athl Train. 1997;32(1):34-9.
Voss DE, Ionta MK, Myers BJ. Proprioceptive neuromuscular facilitation : patterns and techniques (3rded).USA. Harper&Row.1985.
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Some new research data has just been published telling us what we knew already – processed foods are thought to be cancer-causing, with a 12% increase in cancer risk for every 10% increase in ultra-processed foods eaten.
..So it made me wonder what the difference was between this so-called "ultra-processed" or "highly-processed" food and the ordinary run-of-the-mill "processed" junk (I really do hesitate to call it "food", being that it's designed in laboratories and produced in factories) that's everywhere these days. As it turned out…not a lot.
Well, looking at the lists and photos above, don't this lot appear to account for pretty much ALL the types of processed foods that the vast majority of people around us are eating?
It made me wonder whether there had been some behind the doors political pressure put on the researchers to avoid simply stating in the title of the research study that it was just ordinary "processed" food that was being studied.
It appears they reserved that prosaic definition of merely "processed" for such items as cheeses and canned vegetables.
Consumption of fresh or minimally processed foods – such as fruit, vegetables, pulses, rice, pasta, eggs, meat, fish and milk – was associated with the lowest risks of overall cancer and breast cancer. If they had then separated out the latter meat foods and just looked at plant foods, any association with cancer risks would have been closer to zero.
Oddly inconsistent quotes from the same study author – these processed foods are shown as increasing "overall – and specifically breast, cancer" risk – something to be really worried about and, in keeping with this, she adds "apply the principle of precaution". But then she throws in that "In Europe we have over 400 authorised additives. Most of them are probably safe, we need not be too alarmist" (getting confused yet?). And then she drops the bombshell at the end that it would be "better to eat raw or minimally processed food".
So do we eat them or not? Or just cross our fingers when we eat them and hope we don't get cancer?
There's an old saying: You can fool some of the people all of the time, and all the people some of the time, but you can't fool all of the people all of the time.
Whilst all this shilly-shally wordplay continues, whole generations of children are growing up addicted (and I used that word intentionally) to fabricated dietary products that are arguably injuring their bodies and shortening their lifespans.
Hopefully the – by now – rather confused average reader will get some clarification from the spokesman for the National Obesity Forum.
both the World Cancer Research Fund and International Agency for Research on Cancer (IARC) believe that being overweight is the biggest preventable cause of cancer after smoking.
Nothing tastes better than good health…Yum! Yum!
OBJECTIVE: To assess the prospective associations between consumption of ultra-processed food and risk of cancer.
SETTING AND PARTICIPANTS: 104 980 participants aged at least 18 years (median age 42.8 years) from the French NutriNet-Santé cohort (2009-17). Dietary intakes were collected using repeated 24 hour dietary records, designed to register participants' usual consumption for 3300 different food items. These were categorised according to their degree of processing by the NOVA classification.
MAIN OUTCOME MEASURES: Associations between ultra-processed food intake and risk of overall, breast, prostate, and colorectal cancer assessed by multivariable Cox proportional hazard models adjusted for known risk factors.
RESULTS: Ultra-processed food intake was associated with higher overall cancer risk (n=2228 cases; hazard ratio for a 10% increment in the proportion of ultra-processed food in the diet 1.12 (95% confidence interval 1.06 to 1.18); P for trend<0.001) and breast cancer risk (n=739 cases; hazard ratio 1.11 (1.02 to 1.22); P for trend=0.02). These results remained statistically significant after adjustment for several markers of the nutritional quality of the diet (lipid, sodium, and carbohydrate intakes and/or a Western pattern derived by principal component analysis).
CONCLUSIONS: In this large prospective study, a 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increase of greater than 10% in risks of overall and breast cancer. Further studies are needed to better understand the relative effect of the various dimensions of processing (nutritional composition, food additives, contact materials, and neoformed contaminants) in these associations.
104 980 participants aged at least 18 years (median age 42.8 years) from the French NutriNet-Santé cohort (2009-17). Dietary intakes were collected using repeated 24 hour dietary records, designed to register participants' usual consumption for 3300 different food items. These were categorised according to their degree of processing by the NOVA classification.
Fiolet T, Srour B, Sellem , Kesse-Guyot , Allès B, Méjean C, Deschasaux M, Fassier P, Latino-Martel P, Beslay M, Hercberg S, Lavalette C, Monteiro CA, Julia C, Touvier M. BMJ. 2018 Feb 14;360:k322. doi: 10.1136/bmj.k322.
Next Next post: Casein in Dairy = Cancer in Humans?
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This section provides guidance on the treatment of chronic HCV infection in HIV/HCV-coinfected patients. For individuals with acute HCV infection, please refer to the Acute HCV section. HIV/HCV-coinfected patients suffer from more liver-related morbidity and mortality, nonhepatic organ dysfunction, and overall mortality than HCV-monoinfected patients (Lo Re, 2014); (Chen, 2009). Even in the potent HIV antiretroviral therapy era, HIV infection remains independently associated with advanced liver fibrosis and cirrhosis in patients with HCV coinfection (Thein, 2008a); (de Ledinghen, 2008); (Fierer, 2013); (Kirk, 2013).
Similar to HCV-monoinfected patients, HIV/HCV-coinfected patients cured with PEG-IFN/ribavirin have lower rates of hepatic decompensation, hepatocellular carcinoma (HCC), and liver-related mortality (Berenguer, 2009); (Limketkai, 2012); (Mira, 2013). Uptake of HCV therapy was lower in the HIV/HCV-coinfected population, owing to historically lower response rates, patient comorbidities, patient and practitioner perceptions, and adverse events associated with IFN-based therapy (Mehta, 2006a); (Thomas, 2008). With the availability of HCV direct-acting antivirals (DAAs), these barriers should diminish; however, treatment of HIV/HCV-coinfected patients requires continued awareness and attention to the complex drug interactions that can occur between DAAs and antiretroviral medications. Drug interactions with DAAs and antiretroviral agents are summarized below as well as in the Department of Health and Human Services treatment guidelines, www.aidsinfo.nih.gov. Another resource for screening for drug interactions with DAAs is the University of Liverpool website, www.hep-druginteractions.org.
Listed in order of level of evidence, then within group alphabetically.
Antiretroviral drug switches, when needed, should be done in collaboration with the HIV practitioner. For HIV antiretroviral and HCV direct-acting antiviral combinations not addressed below, expert consultation is recommended.
Daclatasvir requires dose adjustment with ritonavir-boosted atazanavir (a decrease to 30 mg daily) and efavirenz or etravirine (an increase to 90 mg daily).
Elbasvir/grazoprevir should be used with antiretroviral drugs with which it does not have clinically significant interactions: abacavir, emtricitabine, enfuvirtide, lamivudine, raltegravir, dolutegravir, rilpivirine, and tenofovir.
Simeprevir should be used with antiretroviral drugs with which it does not have clinically significant interactions: abacavir, emtricitabine, enfuvirtide, lamivudine, maraviroc, raltegravir, (and probably dolutegravir), rilpivirine, and tenofovir.
Sofosbuvir/velpatasvir can be used with most antiretrovirals, but not efavirenz or etravirine. Because velpatasvir increases tenofovir levels, when given as tenofovir disoproxil fumarate (TDF), concomitant use mandates consideration of renal function and should be avoided in those with eGFR below 60 mL/min. In patients with eGFR > 60 mL/min concomitant dosing of velpatasvir and TDF with ritonavir-boosted or cobicistat-boosted regimens did not result in renal toxicity in 56 subjects. Renal monitoring is recommended during the dosing period. Tenofovir alafenamide (TAF) may be an alternative to TDF during sofosbuvir/velpatasvir treatment for patients who take cobicistat or ritonavir as part of their antiretroviral therapy.
Ledipasvir/sofosbuvir can be used with most antiretrovirals. Because ledipasvir increases tenofovir levels, when given as tenofovir disoproxil fumarate (TDF), concomitant use mandates consideration of estimated glomerular filtration rate (eGFR) and should be avoided in those with eGFR below 60 mL/min. Because potentiation of this effect occurs when TDF is used with ritonavir-boosted or cobicistat-boosted regimens, ledipasvir should be avoided with this combination (pending further data) unless antiretroviral regimen cannot be changed and the urgency of treatment is high. Tenofovir alafenamide (TAF) may be an alternative to TDF during ledipasvir/sofosbuvir treatment for patients who take cobicistat or ritonavir as part of their antiretroviral therapy.
For combinations expected to increase tenofovir levels, baseline and ongoing assessment for tenofovir nephrotoxicity is recommended.
The dose of ritonavir used for boosting of HIV protease inhibitors may need to be adjusted (or held) when administered with paritaprevir/ritonavir/ombitasvir plus dasabuvir and then restored when HCV treatment is completed. The HIV protease inhibitor should be administered at the same time as the fixed-dose HCV combination.
Antiretroviral treatment interruption to allow HCV therapy is Not Recommended.
Elbasvir/grazoprevir should NOT be used with cobicistat, efavirenz, etravirine, nevirapine, or any HIV protease inhibitor.
Sofosbuvir/velpatasvir should NOT be used with efavirenz, etravirine, or nevirapine.
Sofosbuvir-based regimens should NOT be used with tipranavir.
Paritaprevir/ritonavir/ombitasvir plus dasabuvir should NOT be used with darunavir, efavirenz, ritonavir-boosted lopinavir, ritonavir-boosted tipranavir, etravirine, nevirapine, cobicistat, or rilpivirine.
Paritaprevir/ritonavir/ombitasvir with or without dasabuvir should NOT be used in HIV/HCV-coinfected individuals who are not taking antiretroviral therapy.
Ribavirin should NOT be used with didanosine, stavudine, or zidovudine.
Simeprevir should NOT be used with cobicistat, efavirenz, etravirine, nevirapine, or any HIV protease inhibitor.
Extensive recommendations for antiretroviral therapy use, including for persons anticipating HCV treatment, are found at jama.jamanetwork.com and aidsinfo.nih.gov.
Antiretroviral drug switches may be performed to allow compatibility of DAAs, with the goal of maintaining HIV suppression without compromising future options. Considerations include prior treatment history, responses to antiretroviral therapy, resistance profiles, and drug tolerance (Gunthard, 2014); (Panel on Antiretroviral Guidelines for Adults and Adolescents, 2014; aidsinfo.nih.gov). Treatment interruption in HIV/HCV-coinfected individuals is not recommended, as it is associated with increased cardiovascular events (Strategies for Management of Antiretroviral Therapy (SMART) Study Group, 2006) and increased rates of fibrosis progression and liver-related events (Tedaldi, 2008); (Thorpe, 2011). If HCV treatment is nonurgent and antiretroviral compatibility and safety with DAAs is unclear, expert consultation should be sought or postponing HCV treatment should be considered until additional data are available.
Daclatasvir is approved by the US Food and Drug Administration (FDA) for use in combination with sofosbuvir for persons with HCV genotype 3 infection. Daclatasvir is a substrate and a very weak inducer of CYP3A4 and a substrate and inhibitor of P-gp. Daclatasvir also inhibits OATP1B1, BCRP, and organic cation transporter 1. Given that daclatasvir is a CYP3A4 substrate, it is susceptible to drug interactions with potent inducers and inhibitors of this enzyme. An increased dose of daclatasvir (120 mg vs 60 mg) was studied in combination with efavirenz, a potent CYP3A4 inducer, in uninfected volunteers. The results suggested that doubling the daclatasvir dose was excessive, and based on modeling and simulation, a 90 mg dose of daclatasvir is recommended with efavirenz (Bifano, 2013). A reduced dose of daclatasvir (20 mg vs 60 mg) was studied in combination with ritonavir-boosted atazanavir, a potent CYP3A4 inhibitor, in uninfected volunteers. The results suggested that dose reduction of daclatasvir to 20 mg was excessive, and based on modeling and simulation, a 30 mg dose of daclatasvir is recommended with ritonavir-boosted atazanavir. Based on the results of this study, a similar interaction was expected with ritonavir-boosted darunavir or lopinavir, and individuals received a reduced dose of daclatasvir 30 mg in the ALLY-2 trial (described below). Subsequent studies suggested that individuals should receive full doses of daclatasvir 60 mg with ritonavir-boosted darunavir or lopinavir. The pharmacokinetics of darunavir and lopinavir are not substantially affected by daclatasvir (Gandhi, 2015). Daclatasvir does not have clinically significant interactions with tenofovir (Bifano, 2013) or dolutegravir (Song, 2015). Daclatasvir has not been studied with emtricitabine, abacavir, rilpivirine, raltegravir, cobicistat-boosted elvitegravir, or maraviroc, but substantial interactions are not expected based on the pharmacology of these agents. There is potential for a decrease in daclatasvir levels with etravirine, and an increased dose (90 mg) of daclatasvir is recommended when used with etravirine, as with efavirenz. Antiretroviral agents allowed in the ALLY-2 trial, which determined the safety and efficacy of daclatasvir and sofosbuvir in HIV/HCV-coinfected individuals, were ritonavir-boosted atazanavir, darunavir, or lopinavir, efavirenz, nevirapine, rilpivirine, raltegravir, and dolutegravir (Wyles, 2015).
Elbasvir is a substrate for CYP3A4 and P-gp. Elbasvir is an inhibitor of the drug transporters BCRP and P-gp. Grazoprevir is a substrate for CYP3A4, P-gp and OATP1B1. Moderate and strong CYP3A and P-gp inducers (including efavirenz) are not recommended for coadministration with EBR/GZR. OATP1B1 inhibitors are also not recommended with grazoprevir. In terms of its ability to act as a perpetrator in interactions, grazoprevir is an inhibitor of CYP3A4 (weak), UGT1A1 (weak), and BCRP. Elbasvir 50 mg and grazoprevir 100 mg are only available in a fixed-dose combination (hereafter, elbasvir/grazoprevir).
Elbasvir/grazoprevir is incompatible with all ritonavir-boosted HIV protease inhibitors and efavirenz. While this DAA combination has not been studied with etravirine or cobicistat-boosted elvitegravir, drug interactions are expected and these combinations should be avoided. Elbasvir/grazoprevir is compatible with raltegravir, dolutegravir, rilpivirine, and the HIV nucleos(t)ide analogs.
Sofosbuvir is not metabolized nor does it induce or inhibit any cytochrome P450 (CYP) enzymes. Sofosbuvir is a substrate (but not an inhibitor) of the drug transporters, p-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Drug interaction studies with antiretroviral drugs (ie, efavirenz, tenofovir, emtricitabine, rilpivirine, ritonavir-boosted darunavir, and raltegravir) in uninfected persons identified no clinically significant interactions (Kirby, 2012). Sofosbuvir is not recommended for use with tipranavir because of the potential of this antiretroviral drug to induce P-gp (see sofosbuvir prescribing information).
Ledipasvir is available only in a fixed-dose combination tablet with sofosbuvir (hereafter ledipasvir/sofosbuvir). Ledipasvir undergoes minimal metabolism and does not inhibit or induce CYP enzymes. Ledipasvir is a substrate of P-gp and an inhibitor of P-gp and BCRP. Drug interaction studies of ledipasvir (with or without sofosbuvir) with antiretroviral drugs in uninfected persons did not identify clinically significant interactions with abacavir, dolutegravir, emtricitabine, lamivudine, raltegravir, or rilpivirine (German, 2014); (Garrison, 2015). Interactions with maraviroc and enfuvirtide are not expected based on their pharmacologic profiles. Ledipasvir area under the curve (AUC) is decreased by 34% when coadministered with efavirenz-containing regimens and increased by 96% when coadministered with ritonavir-boosted atazanavir (German, 2014). No dose adjustments of ledipasvir are recommended to account for these interactions.
Ledipasvir increases tenofovir levels, which may increase the risk of tenofovir-associated renal toxicity. The magnitude of the increase in tenofovir levels is dependent on the tenofovir formulation used (ie, tenofovir disoproxil fumarate [TDF] or tenofovir alafenamide [TAF]) and other concomitant antiretroviral drugs. With the addition of ledipasvir/sofosbuvir, tenofovir levels (when given as TDF) are increased with efavirenz, rilpivirine, (German, 2014) dolutegravir, ritonavir-boosted atazanavir, and ritonavir-boosted darunavir (German, 2015). The absolute tenofovir levels are highest when TDF is administered with ritonavir-boosted protease inhibitors. When ledipasvir/sofosbuvir is administered to individuals taking TDF and ritonavir-boosted HIV protease inhibitors, the tenofovir levels exceed those deemed renally safe. Thus, to date, individuals receiving ritonavir-boosted HIV protease inhibitors have been excluded from clinical studies of ledipasvir/sofosbuvir. Individuals receiving elvitegravir and cobicistat have also been excluded from clinical studies of ledipasvir/sofosbuvir because cobicistat trough levels are increased 4-fold (see ledipasvir and sofosbuvir prescribing information) by ledipasvir.
In the ERADICATE study, ledipasvir/sofosbuvir was administered to 37 HIV/HCV-coinfected patients taking combination antiretroviral therapy, including 16 taking regimens containing tenofovir disoproxil fumarate, emtricitabine, and efavirenz, and all with baseline eGFR of 60 mL/min or higher (Osinusi, 2014). Changes in creatinine level or glomerular filtration rate (GFR) in these 37 patients were similar to patients not taking antiretroviral therapy. Further safety data from the phase III ION-4 study are described below regarding interactions between ledipasvir/sofosbuvir and raltegravir, rilpivirine, or efavirenz, each in combination with fixed-dose tenofovir disoproxil fumarate and emtricitabine.
Renal parameters should therefore be checked at baseline and regularly thereafter while on therapy when ledipasvir/sofosbuvir is administered with tenofovir disoproxil fumarate-containing regimens. Baseline parameters should include measuring creatinine level, electrolytes (including phosphorus), and urinary protein and glucose measurements, according to recent guidelines for management of chronic kidney disease in those with HIV that include indications for nephrology consultation (Lucas, 2014). Changing antiretroviral therapy or delaying HCV treatment if nonurgent may be considered for those at high risk for renal toxicity (especially those with an eGFR between 30 mL/min and 60 mL/min or who have preexisting evidence of Fanconi syndrome) and particularly those taking tenofovir disoproxil fumarate and a ritonavir-boosted HIV protease inhibitor, as there are currently few efficacy or safety data for these combinations (see ledipasvir/sofosbuvir prescribing information). If the urgency of HCV treatment and the risk of switching antiretroviral regimens are both high and there is no safer alternative to ledipasvir/sofosbuvir, then frequent monitoring (every 2-4 weeks) of urine parameters is recommended for concomitant use with tenofovir disoproxil fumarate and a ritonavir-boosted HIV protease inhibitor. Tenofovir disoproxil fumarate should also be properly dosed and adjusted for eGFR at baseline and while on therapy (Lucas, 2014).
Though there is an absence of data at this time on the renal safety of tenofovir when given as TAF with ledipasvir/sofosbuvir, a study of tenofovir pharmacokinetics in healthy volunteers receiving the combination of TAF, emtricitabine, and cobicistat-boosted elvitegravir with ledipasvir/sofosbuvir found that tenofovir levels were only 20% of the typical tenofovir exposures seen with TDF (Garrison, 2015). Based on these pharmacokinetic data in healthy volunteers, TAF may be an alternative to TDF during ledipasvir/sofosbuvir treatment for patients who take elvitegravir/cobicistat or ritonavir-boosted HIV protease inhibitors as part of their antiretroviral therapy; however, there are no safety data for this combination in coinfected patients.
Based on data in healthy volunteers, tenofovir pharmacokinetics are lower with tenofovir alafenamide (TAF) relative to TDF, thus TAF may be an alternative to TDF during ledipasvir/sofosbuvir treatment for patients who take elvitegravir/cobicistat or ritonavir-boosted HIV protease inhibitors as part of their antiretroviral therapy, however there are no safety data for this combination in coinfected patients.
Paritaprevir is an inhibitor of the organic anion-transporting polypeptide 1B1 (OATP1B1). Ritonavir is coformulated with paritaprevir and ombitasvir and used to improve the pharmacokinetics of paritaprevir. As ritonavir has anti-HIV activity, HIV/HCV-coinfected patients should have achieved HIV RNA suppression prior to initiation of this regimen; those not taking antiretroviral therapy should avoid use of this fixed-dose combination due to the potential for low-dose ritonavir to select for HIV protease-inhibitor resistance.
Ritonavir-boosted paritaprevir, ombitasvir, and dasabuvir are metabolized by, and inhibitors of CYP enzymes (3A4 and 2C8), P-gp, BCRP and the hepatic uptake transporter OATP1B1. Studies of uninfected volunteers did not reveal notable pharmacologic interactions with paritaprevir (150 mg), ritonavir (100 mg), and ombitasvir (25 mg) plus dasabuvir (250 mg) (hereafter PrOD) or tenofovir disoproxil fumarate and emtricitabine (when tested separately from other fixed-dose combinations), raltegravir, (Khatri, 2015b) abacavir, lamivudine, or dolutegravir (Khatri, 2015). In uninfected volunteers, when PrOD was combined with efavirenz, emtricitabine, and tenofovir disoproxil fumarate, clinically significant gastrointestinal and neurologic adverse events occurred, coincident with elevations of alanine aminotransferase levels. When PrOD was combined with rilpivirine, exposures to rilpivirine were substantially increased. Therefore, rilpivirine and efavirenz should not be used with PrOD.
Because ritonavir is a component of the fixed-dose combination of paritaprevir and ombitasvir, the total daily dose of ritonavir must be carefully considered when using PrOD with ritonavir-boosted HIV protease inhibitors. Coadministration with ritonavir-boosted lopinavir would result in a 300 mg daily dose of ritonavir, a dose associated with substantial gastrointestinal adverse effects; this combination is not recommended. Once- and twice-daily doses of darunavir have been studied with PrOD in uninfected individuals. Darunavir trough levels are lowered 48% and 43% with once- and twice-daily doses of darunavir, respectively. The average absolute darunavir trough levels in these studies were 30% to 50% of typical values. Paritaprevir AUC is increased 30% with once-daily darunavir and decreased 41% with twice-daily darunavir. The mechanism and clinical significance of the discrepant effect on paritaprevir is unclear. Thus, PrOD should not be used with ritonavir-boosted darunavir pending further data. PrOD can be given with atazanavir, but the separate ritonavir boosting tablet should be held during PrOD therapy and atazanavir should be administered at the same time as the fixed-dose combination of ritonavir-boosted paritaprevir and ombitasvir. Paritaprevir levels are increased 1.5- to 3-fold with atazanavir, but no dose adjustment of paritaprevir is recommended (Khatri, 2016). Inhibition of OATP1B1 by PrOD increases indirect bilirubin concentrations, and this effect may be attenuated in individuals taking atazanavir (Eron, 2014).
Twenty-eight HIV/HCV-coinfected subjects already taking ritonavir-boosted atazanavir (with ritonavir coming from the HCV regimen during the time of coadministration) were treated with a regimen of PrOD and ribavirin as part of the TURQUOISE-1 study (Sulkowski, 2015).
Simeprevir is metabolized primarily by CYP3A4 and is therefore susceptible to drug interactions with inhibitors and inducers of this enzyme. Simeprevir is also an inhibitor of OATP1B1 and P-gp. Drug interaction studies with antiretroviral drugs in HIV-uninfected volunteers suggested no substantial interactions with tenofovir, rilpivirine, or raltegravir; however, simeprevir concentrations were substantially decreased when dosed with efavirenz and substantially increased when dosed with ritonavir-boosted darunavir. Use with efavirenz, etravirine, cobicistat, or boosted HIV protease inhibitors is not recommended (Kiser, 2013).
Velpatasvir is available only in a fixed-dose combination tablet with sofosbuvir (hereafter sofosbuvir/velpatasvir). Velpatasvir is metabolized by CYP3A4, CYP2C8, and CYP2B6. It does not appear to inhibit or induce any CYP enzymes. Velpatasvir is a substrate for P-gp and BCRP, and inhibits P-gp, BCRP, and OATP1B1/1B3, but does not induce any transporters. Velpatasvir absorption is pH-dependent. Refer to product labeling for guidance on temporal separation and dosing of gastric acid modifying agents.
Drug interaction studies with sofosbuvir/velpatasvir have been performed in HIV and HCV seronegative volunteers. As with ledipasvir/sofosbuvir, tenofovir exposures are increased, which may be problematic for individuals with eGFR values of less than 60 mL/min or in those receiving ritonavir or cobicistat-containing antiretroviral therapy with tenofovir disoproxil fumarate (TDF). Fifty-six HIV/HCV coinfected individuals receiving the combination of TDF with ritonavir or cobicistat-containing antiretroviral therapy were treated with sofosbuvir/velpatasvir in the ASTRAL-5 study with no difference in median creatinine clearance before and after sofosbuvir/velpatasvir treatment, but poor renal function was an exclusion for this study. Consider the use of tenofovir alafenamide (TAF) in place of TDF in those requiring ritonavir or cobicistat-containing antiretroviral therapy. If the combination of TDF with a ritonavir- or cobicistat-containing antiretroviral therapy is required, renal parameters should be checked at baseline and regularly thereafter while on sofosbuvir/velpatasvir. Velpatasvir exposures are significantly reduced with efavirenz and this combination is not recommended. Etravirine has not been studied with sofosbuvir/velpatasvir but is also not recommended. Indirect bilirubin level increases have been reported when sofosbuvir/velpatasvir was used in patients on atazanavir/ritonavir. These changes are not considered clinically significant.
Based on data in healthy volunteers, tenofovir pharmacokinetics are lower with tenofovir alafenamide (TAF) relative to TDF, thus TAF may be an alternative to TDF during sofosbuvir/velpatasvir treatment for patients who take elvitegravir/cobicistat or ritonavir-boosted HIV protease inhibitors as part of their antiretroviral therapy, however there are no safety data for this combination in coinfected patients.
a Only problematic when administered with tenofovir disoproxil fumarate; tenofovir levels are increased.
b Decrease daclatasvir dose to 30 mg once daily with atazanavir; increase daclatasvir dose to 90 mg once daily with efavirenz or etravirine.
c PrOD administered with efavirenz led to premature study discontinuation owing to toxic effects.
Ribavirin has the potential for dangerous drug interactions with didanosine resulting in mitochondrial toxicity with hepatomegaly and steatosis, pancreatitis, and lactic acidosis; thus, concomitant administration of these 2 drugs is contraindicated (Fleischer, 2004). The combined use of ribavirin and zidovudine has been reported to increase the rates of anemia and the need for ribavirin dose reduction; thus, zidovudine is not recommended for use with ribavirin (Alvarez, 2006).
Daily daclatasvir (refer above for dose) plus sofosbuvir (400 mg), with or without ribavirin (refer to Initial Treatment of HCV Infection and Retreatment of Persons in Whom Prior Therapy Has Failed sections for duration) is a Recommended regimen when antiretroviral regimen changes cannot be made to accommodate alternative HCV direct-acting antivirals.
Treatment courses shorter than 12 weeks, such as the use of 8 weeks of ledipasvir/sofosbuvir.
Although fewer HIV/HCV-coinfected patients than HCV-monoinfected patients have been treated in trials of DAAs, efficacy rates thus far have been remarkably similar between the groups (Sulkowski, 2013); (Sulkowski, 2014); (Dieterich, 2014b); (Rodriguez-Torres, 2015); (Osinusi, 2015); (Sulkowski, 2015); (Dieterich, 2015); (Naggie, 2015); (Wyles, 2015). Thus, results from HCV monoinfection studies largely justify the recommendations for HIV/HCV coinfection (discussed in the Initial Treatment and Retreatment sections). Discussion specific to studies of HIV/HCV coinfection is included here.
ALLY-2 is a phase III clinical trial that evaluated the 12-week regimen of daclatasvir with sofosbuvir in patients with HIV/HCV coinfection and HCV genotypes 1 to 4 (Wyles, 2015). This open-label clinical trial enrolled both treatment-naïve (n=151) and -experienced (n=52) HIV/HCV-coinfected patients. Treatment-naïve patients were randomly assigned (2:1), with stratification by cirrhosis status and HCV genotype, to receive 12 weeks or 8 weeks of once-daily daclatasvir 60 mg (dose adjusted based on antiretroviral regimen) and sofosbuvir 400 mg; treatment-experienced patients received daclatasvir and sofosbuvir for 12 weeks. Genotype distribution was 83%, 9%, 6%, and 2% of patients, respectively, for genotypes 1, 2, 3, and 4 HCV infection, and 14% of all participants had cirrhosis. Antiretroviral drugs allowed were ritonavir-boosted darunavir, atazanavir, or lopinavir, efavirenz, nevirapine, rilpivirine, raltegravir, and dolutegravir. The combination of daclatasvir and sofosbuvir once daily for 12 weeks achieved an SVR12 in 97% of HIV/HCV-coinfected patients with HCV genotype 1, 2, 3, or 4, and was safe and well tolerated. Ninety-seven percent of treatment-naïve patients and 98% of -experienced patients achieved an SVR. However, among patients who received 8 weeks of combination therapy, only 76% of patients achieved an SVR. Factors associated with relapse in this patient group included high baseline HCV RNA level (>2 million IU/mL; 69%), concomitant use of a boosted darunavir-based antiretroviral regimen with 30 mg of daclatasvir (67%), and the presence of cirrhosis (60%). More data are needed in certain subgroups (eg, patients with HCV genotype 3 and cirrhosis who had lower response rates to this regimen and patients without HIV infection) (Nelson, 2015).
Many HIV/HCV-coinfected patients are on antiretroviral regimens with drug interactions that absolutely preclude otherwise recommended DAA regimens. Switching an optimized antiretroviral regimen carries risks, including adverse effects and HIV viral breakthrough (Eron, 2010). HIV viral breakthrough is a particular concern for those with substantial antiretroviral experience or known resistance to antiretroviral drugs. For these situations, given the compatibility of daclatasvir and sofosbuvir with nearly all antiretroviral regimens (see pharmacologic considerations above), daclatasvir and sofosbuvir is recommended in order to avoid unnecessary switching of effective HIV antiretroviral regimens. When the optimal combination of DAAs and antiretroviral drugs is unclear, expert consultation is recommended.
The safety, tolerability, and efficacy of a novel second-generation NS3/4A serine protease inhibitor grazoprevir (MK-5172) plus NS5A inhibitor, elbasvir (MK-8742) was assessed in patients with HCV and HIV coinfection in this study. C-EDGE was a phase III, non-randomized, open-label, single-arm study in which treatment-naïve patients with chronic HCV genotype 1, 4, or 6 infection and HIV coinfection, with or without cirrhosis, were enrolled in Europe, the USA, and Australia (Rockstroh, 2015). All patients were either naïve to treatment with any antiretroviral therapy (ART) with a CD4+ T cell count more than 500 cells/mm3 (N=211) or stable on current ART for at least 8 weeks with a CD4+ T cell count more than 200 cells/mm3 (N=7) and undetectable HIV RNA levels. All 218 enrolled patients received elbasvir (50 mg) plus grazoprevir (100 mg) in a single-pill combination (elbasvir/grazoprevir) once daily for 12 weeks. All 218 patients completed follow-up at week 12. Median baseline CD4+ T cell counts were 568 (424-626) cells/mm3. Limited ARVs were allowed: specifically a nucleoside/nucleotide backbone of abacavir (21.6%) versus tenofovir (75.2%), in combination with raltegravir (52%), dolutegravir (27%), or rilpivirine (17%). SVR12 was achieved by 210 (96%) of 218 patients (95% CI 92.9–98.4). One patient did not achieve SVR12 because of a non-virological reason, and seven patients without cirrhosis relapsed (two subsequently confirmed as reinfections, highlighting the requirement of continued harm-reduction strategies post SVR). Thirty-five patients with cirrhosis achieved SVR12. The most common adverse events were fatigue (29; 13%), headache (27; 12%), and nausea (20; 9%). No patient discontinued treatment because of an adverse event. Three out of six patients who relapsed before SVR12 had NS3 and/or NS5A RASs, while the others had wild type at the time of relapse. Two patients receiving ART had transient HIV viremia, but subsequently retuned to undetectable levels without change in ART. No significant changes were observed with CD4+ T cell counts or new opportunistic infections. Elbasvir/grazoprevir without ribavirin seems to be effective and well tolerated for patients coinfected with HIV with or without cirrhosis. These data are consistent with previous trials of this regimen in the monoinfected population (Zeuzem, 2017).
The safety and efficacy of 12 weeks of ledipasvir/sofosbuvir was evaluated in the phase II ERADICATE study, which treated 50 HIV/HCV-coinfected, HCV genotype 1-infected, treatment-naïve patients without cirrhosis from an urban population in a single-center, open-label clinical trial (Osinusi, 2015). Thirteen patients were not receiving antiretroviral therapy and 37 patients were on protocol-allowed medications (tenofovir, emtricitabine, rilpivirine, raltegravir, and efavirenz). Although the inclusion criteria for patients receiving antiretroviral therapy allowed CD4+ T cell counts of greater than 100/µL, the median CD4+ T cell count was 576/µL. Overall, 98% achieved sustained virologic response at 12 weeks (SVR12; 13/13 in treatment-naïve arm and 36/37 in treatment-experienced arm). There were no deaths, discontinuations, or clinically significant serious adverse events. Renal function was monitored frequently during this trial and after administration of study drugs using a battery of tests (serum creatinine, eGFR, urinary beta-2 microglobulin, proteinuria, and glycosuria). No clinically significant changes in these parameters or renal toxicity were observed. A larger study, ION-4, reported similar outcomes with ledipasvir/sofosbuvir (Naggie, 2015). A total of 335 HCV treatment-naïve and -experienced HIV/HCV-coinfected patients were enrolled in the study and received ledipasvir/sofosbuvir once daily for 12 weeks. Patients received tenofovir disoproxil fumarate and emtricitabine with raltegravir (44%), efavirenz (48%), or rilpivirine (9%). HCV genotypes included were 1a (75%), 1b (23%), and 4 (2%); 20% of patients had cirrhosis, 34% were black, and 55% had not responded to prior HCV treatment. Overall, the SVR12 rate was 96% (321/335); 2 patients had on-treatment virologic failure judged to be a result of nonadherence, 10 had virologic relapse after discontinuing treatment, 1 died from endocarditis associated with injection drug use, and 1 was lost to follow-up. SVR12 rate was 94% (63/67) among patients with cirrhosis and 97% (179/185) among treatment-experienced patients. No patients discontinued the study drug because of an adverse event. Although all patients had GFRs above 60 mL/min at study entry, drug interaction studies suggested that some patients would have elevated levels of tenofovir disoproxil fumarate. There were 4 patients in whom serum creatinine level rose to 0.4 mg/dL or higher: 2 remained on tenofovir, 1 had the tenofovir dose reduced, and the other stopped taking tenofovir. Neither study reported clinically significant changes in CD4+ T cell counts or HIV RNA levels in the study subjects. Thus, these data suggest that 12 weeks of ledipasvir/sofosbuvir is a safe and effective regimen for HIV/HCV-coinfected patients with HCV genotype 1 taking select antiretroviral therapy (Osinusi, 2015); (Naggie, 2015). There are limited data regarding an 8-week duration of ledipasvir/sofosbuvir in HIV/HCV-coinfected patients (Ingiliz, 2016). Therefore, a shortened treatment course for HIV-infected persons cannot be recommended at this time.
PrOD was FDA-approved for use in HCV genotypes 1a and 1b because of its efficacy and safety in treatment-naïve patients and PEG-IFN/ribavirin treatment-experienced patients with and without cirrhosis. Available information about response rates with this regimen in HIV/HCV-coinfected patients comes from the first part of the phase II TURQUOISE-1 study. In this study, treatment-naïve (n=42) and -experienced (n=21) patients were randomly assigned to receive either 12 weeks or 24 weeks of PrOD and weight-based ribavirin (100 mg [<75 kg] to 1200 mg [≥75 kg]). Of the 63 study subjects, 12 had cirrhosis, 56 had HCV genotype 1a, and 7 had HCV genotype 1b. Two study-permitted antiretroviral regimens were chosen based on pharmacokinetic data from uninfected volunteers: 35 patients entered taking tenofovir disoproxil fumarate and emtricitabine with raltegravir and 28 patients entered taking tenofovir disoproxil fumarate and emtricitabine with ritonavir-boosted atazanavir (with the ritonavir coming from the HCV regimen during the time of coadministration). Of the 31 patients who received 12 weeks of PrOD and ribavirin, 29 (93.5%) achieved an SVR12, 1 relapsed, and 1 withdrew consent from study participation. Similarly, of the 32 subjects in the 24-week arm, 29 (90.6%) achieved an SVR12, 1 experienced viral breakthrough, and 2 had apparent HCV reinfection. No treatment-related serious adverse events occurred and no subjects discontinued treatment because of medication intolerance (Sulkowski, 2015).
The combination of simeprevir plus sofosbuvir with or without ribavirin has been studied in the phase II COSMOS trial in patients with HCV monoinfection (Lawitz, 2014b). This study is the main basis for the recommendation supporting the use of this all-oral combination for HCV genotype 1a or 1b monoinfection. Simeprevir plus sofosbuvir has been used anecdotally in patients with HIV/HCV coinfection, with a recent report of achieving an SVR in 11 (92%) of 12 patients (Del Bello, 2016). Despite the dearth of study data, this regimen may be considered for the treatment of HCV genotype 1 infection in patients with HIV infection who are receiving antiretroviral therapy that may be coadministered with simeprevir and sofosbuvir.
Similarly, few data exist for the combination of sofosbuvir plus simeprevir for the retreatment of HCV infection in HIV/HCV-coinfected patients. However, preliminary results obtained for HCV-monoinfected patients, including those with prior treatment failure and advanced fibrosis, support the expectation that this regimen will be highly effective in HIV/HCV-coinfected patients receiving compatible antiretroviral therapy as described above (see Retreatment of HCV-monoinfected patients); (Lawitz, 2014b).
The safety and efficacy of 12 weeks of sofosbuvir/velpatasvir was evaluated in a phase 3 study of 106 antiretroviral controlled HIV/HCV coinfected subjects (Wyles, 2016). HCV genotypes 1-4 were included and 18% (n=19) had compensated cirrhosis. HIV was controlled on ART including non-nucleoside reverse-transcriptase inhibitor (NNRTI- rilpivirine), integrase inhibitor (raltegravir or elvitegravir/cobicistat), or ritonavir-boosted protease inhibitor (PI- atazanavir, lopinavir, or darunavir) based regimens with either tenofovir/emtricitabine or abacavir/lamivudine. Fifty-three percent (n=56) of subjects were on tenofovir with a pharmacologic boosting agent (either ritonavir or cobicistat). Neither efavirenz nor etravirine were allowed in this study as concomitant dosing with sofosbuvir/velpatasvir in healthy volunteers resulted in clinically significant decreases in velpatasvir exposures. SVR12 was 95% with 2 relapses, both occurring in genotype 1a-infected patients. Similar results were noted within genotypes, in subjects with cirrhosis and in those with baseline NS5A RASs (n=12 at 15% threshold, SVR12=100%). There was no clinically significant change in serum creatinine or GFR and no subject required a change in their antiretroviral therapy during the study period.
In general, few HIV/HCV-coinfected patients with cirrhosis have been included in clinical trials of DAAs, and no data are available regarding HIV/HCV-coinfected patients with renal insufficiency or who have undergone solid organ transplantation. Despite a lack of data, it is highly likely that response rates are similar to those of HCV-monoinfected patients, as no study thus far in the DAA era has showed a lower efficacy for HIV/HCV-coinfected patients. Therefore, the respective guidance from these sections should be followed if treatment is otherwise warranted, with consideration of drug interactions.
No data currently exist to guide recommendations for the retreatment of HIV/HCV-coinfected patients or for the retreatment of simeprevir- or sofosbuvir-experienced individuals. When treatment is necessary, guidelines for HCV-monoinfected individuals are recommended.
Rarely, genotyping assays may indicate the presence of a mixed infection (eg, genotypes 1a and 2). Treatment data for mixed genotypes with direct-acting antivirals are sparse but utilization of a pangenotypic regimen should be considered. When the correct combination or duration is unclear, expert consultation should be sought.
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Because armed conflict often leads to a disruption of the social ecology of a community, mental health interventions should build on existing local support and services and strengthen capacities within the community.
Behaviour-based strategies should include communication through specific groups and subsets of people.
This type of communication embedded with social and behavioural understanding can have long-lasting results not only within the community, but also in institutions, key players, and other communities and levels of society.
Ultimately, removing the barriers to outbreak response strengthens health and social systems.
Being aware of cultural norms and traditions at various levels (individual, community and international) could ultimately help prevent EVD infection and reduce transmission.
Paraprofessional psychosocial support workers can play a key role in meeting patient needs at the ETU in line with global mental health and psychosocial support guidelines.
Psychosocial interventions need to include a focus on the current social, political and economic context.
By learning to identify feelings and express emotions, children can better cope with the difficulties they face, as well as increase their personal resilience. As the Syrian crisis has entered its seventh year, it has had a negative effect on vulnerable populations, especially children. It should be noted that while not all children have been traumatised, many have experienced conflict and crisis, and in turn face challenges expressing and regulating their emotions and behaviour. The aim of the small study, described in this field report, is to explore the power of using drama and art as tools for Syrian children to help them learn to identify their emotions. The qualitative study was conducted at an informal education centre in southeast Turkey, with 10 children, over the course of five workshops. Basic drama and creative art skills were used to raise awareness about emotions as the first phase of emotion regulation.
Future interventions might create opportunities for targeted, local contact with stigmatized persons; reduce or eliminate negative and stigmatizing names for people with ID; and promote self-help for people with ID and their families.
This field report describes a case study on the applicability of non-violent communication (NVC) within the Syrian refugee context, and the usefulness of theatre of the oppressed techniques in practicing NVC. The intervention was applied to refugee women working or attending activities in a livelihood centre in Turkey. Through the work, NVC was explained and discussed with participants, who brought real-life themes and scenarios to practice learnt skills using theatre of the oppressed techniques. Participants reported improved self-compassion, compassion, communication and collaboration with others. They also reported that such activities changed their view of conflict. Theatre of the oppressed helped participants achieves more empathy and understanding and to try different solutions to scenarios in which they faced conflict.
Creating existential spaces: what do oral history interviews held with Syrian refugee men tell us?
The dominant narratives on refugees evolve around vulnerability and trauma discourse that homogenizes a whole group of individuals as traumatized, therefore, vulnerable, as they exposed to an adversity. It is the self-narratives of refugees that reveal the complexity, uniqueness and totality of each person's experience that can object to this passivation. Oral history in this respect stands as a crucial tool as it creates spaces of existence where refugees can speak freely about their own life stories to the extent and content she/he desires. This small research is a naïve attempt to apply life history approach, and oral history as one of its methodological tool, to psycho-social support at the intersection with refugee studies. Although evolved in different paradigms, this research aims to demonstrate that oral history can also empower refugees since their self-narratives stand as valid sources of reality to challenge the above mentioned discourses, now and then.
Les interventions suggérées comprennent la mise en place de lieu de contacts directs entre les personnes vivant la stigmatisation; la réduction ou l'arrêt de l'utilisation de surnoms négatifs et stigmatisants donnés aux personnes ayant une DI (par exemple : kizengi qui signifie idiot); et la promotion de groupes d'entraide et d'autodéfense des droits des personnes ayant une DI et de leurs familles.
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10. Medical Surveillance and Injury Reporting ›
It is important to report even minor job-related injuries or illness. There are five reasons that employees must promptly report any injury or illness which has occurred at work or where work may have contributed to the injury or illness.
Reporting injuries and illnesses can trigger additional investigation to identify and remediate root causes and prevent future injuries.
Provides your safety committee with data to identify trends and gain support for remediation efforts.
Employer notification is required should the injury result in medical treatment and require worker's compensation payment.
The Institutional Biosafety Committee (IBC) requires that any injury incurred while working on a project approved by the IBC be reported to the IBC (as per National Institutes of Health guidelines and UMN Regents Policy)
OSHA requires an injury log be maintained and reported annually.
Reporting Procedure
The University of Minnesota Office of Risk Management and Insurance oversees the University of Minnesota Administrative Policy "Reporting Workers Compensation Related Injuries", which describes the injury reporting procedure in detail. This procedure is summarized below:
Employee Responsibilities
If you require immediate medical attention, call 911 and seek medical treatment immediately.
In the event of a needlestick, immediately contact the HealthPartners 24-hour CareLine at (612) 339-3663 or 800-551-0859 (TTY 952-883-5474) to receive counseling on appropriate treatment. HealthPartners Occupational and Environmental Medicine Clinics and Urgent Care, and the Emergency Room at Fairview University Medical Center stock the drugs currently recommended for treatment within 1-2 hours of accidental exposures to HIV.
Notify your supervisor as soon as practicable. Your supervisor will assess the situation, assist with arranging proper medical care and begin the injury reporting process.
Work with your supervisor to complete relevant documents.
Supervisor Responsibilities
Immediately assess the incident and assist the Employee in seeking appropriate medical care or necessary treatment for any work-related injury. If the employee requires immediate medical attention, call 911.
As soon as possible, provide the Employee with the following forms:
Minnesota Workers Compensation Information Sheet
List of Designated Medical Providers, and
Temporary Prescription Drug ID card.
Within 8 business hours, complete the online First Report of Injury (eFROI) form.
Within 24 business hours, complete a Supervisor Incident Investigation Report and email ([email protected]) or fax (952) 826-3785) to the Claims Administrator at Sedgwick Claims Management Services.
Information Provided to Physician
The employee's supervisor or department will collect and transmit the following information to the examining physician:
Identification of the hazardous substance(s) to which the employee may have been exposed;
A description of the conditions under which the exposure occurred including quantitative exposure data, if available; and
A description of the signs and symptoms of exposure that the employee is experiencing, if any.
Additional Reporting – Exposures to Biological Agents
In addition to the procedure outlined above, there are specific reporting requirements for any injuries or illnesses that occur while working on an IBC-approved protocol. The IBC injury report form and instructions can be found on the IBC website.
To summarize, send IBC Incident Report Form to the IBC for all incidents involving biohazardous agents. Any accident involving recombinant or synthetic DNA must be reported to the IBC office within 24 hours to meet institutional requirements prescribed by the NIH Guidelines for Research Involving Recombinant DNA Molecules.
Reporting Procedure for UNPAID Students, Guests, and Visitors
The following form should be filled out and emailed or faxed to the Risk Management Office for reporting property damage or injury to UNPAID students, guests, and visitors:
Bodily Injury/Property Damage Incident Report
Workers' Compensation Procedures and Forms
It is very important that even minor job-related injuries or illness are reported. These statistics help the University Health and Safety track trends that may indicate occupational hazards that need evaluation. To report an illness or injury, go to the Workers' Compensation website.
University of Minnesota's Policy for Reporting Workers' Compensation Related Injuries is also available on the web. This policy explains the procedures and provides the necessary reporting forms. Please note that there are additional reporting requirements for any injuries or illnesses that occur while working on an IBC-approved protocol. The IBC injury report form can be found on the IBC website.
For more information, visit the Occupational Health and Safety websitte regarding injury reporting.
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Phytophthora sojae (P. sojae) is the second most destructive pathogen to soybeans; however, the mechanism of its pathogenesis is not well understood. Recent studies have shown that microRNA 393 (miR393) is up-regulated in response to P. sojae infection. Methyl jasmonate (MeJa) is produced by plants in response to wounding. To probe for a possible link between P. sojae infection and a response elicited by MeJa, soybean plants were treated to three conditions and then miR393 expression was monitored using Quantitative Polymerase Chain Reaction (Q-PCR). Treatment groups consisted of a control set of plants, P. sojae-infected plants, and plants treated with MeJa. Soybean roots were inoculated by scraping the soybean roots 1.0 cm from the root end and applying a small plug of P. sojae-infected agar. The MeJa group was treated by exposing the plants to evaporated MeJa in an enclosed container. 8 hours post-treatment, root tissues were harvested and miRNAs were isolated using an Ambion Plant RNA Isolation Aid in conjunction with a mirVana miRNA isolation kit. The quality and quantity of small RNAs was assessed by spectrophotometric analysis and by denaturing polyacrylamide electrophoresis. miRNAs were reverse transcribed into cDNA using a TaqMan microRNA Reverse Transcription System. Q-PCR, with FAM-labeled probes, and the ΔΔCt method were used to measure relative miR393 levels using U6 as an endogenous control.
Oeltjenbruns, Andrew. "The Role of MicroRNA 393 in Defense Against Phytophthora Sojae in Soybeans." Undergraduate Research Symposium, Mankato, MN, April 20, 2015.
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QUESTION: Which interventions prevent ventilator associated pneumonia (VAP) in critically ill patients?
English language studies were identified by searching Medline (1966–2001) and the Cochrane Library, and by reviewing bibliographies of retrieved articles.
Studies were selected if they were randomised controlled trials (RCTs) or observational cohort controlled trials.
Data were extracted on study design, intervention, and outcomes.
34 studies met the selection criteria. Meta-analysis was not done because of study variations in the diagnostic criteria for pneumonia. Results are summarised in the table⇓.
Semirecumbent positioning, stress ulcer prophylaxis (sucralfate rather than H2 antagonists), aspiration of subglottic secretions, selective digestive tract decontamination, and oscillating beds reduce ventilator associated pneumonia (VAP) in select critically ill patients. No evidence currently supports specific methods of enteral feeding or increased frequency of ventilator circuitry changes for prevention of VAP.
The systematic review by Collard et al provides a thorough analysis of the evidence to date, highlighting the considerable gaps in our knowledge. In selecting studies for inclusion, the authors noted the lack of standardised diagnostic criteria, which prevented pooling of individual study results in a meta-analysis. Diagnostic criteria for VAP may include fever, leukocytosis, purulent secretions, and changes on chest radiography and microbiology. Limitations of existing studies included small sample sizes, lack of power, and equivocal and conflicting findings.
Although semirecumbent positioning of all eligible patients appears easy, inexpensive, and relatively uncontroversial, evidence on practices such as oscillation beds and selective digestive decontamination is equivocal. Collard et al correctly attributed these conflicting findings to differences in inclusion criteria, outcome measures, and analyses used in individual studies. They also caution practitioners about the use of selective digestive tract decontamination because of uncertainties about effects of such treatment on antibiotic resistance, although no additional evidence to support this was included in the review.
Although cost may be a barrier for many of these practices, it is important to educate clinicians to take measures to prevent and recognise symptoms, and diagnose VAP. Collard et al also noted that to date, no RCT has evaluated the effectiveness of combined preventative practices. Given the high mortality rate associated with VAP, this research should be a priority.
Chastre J, Fagon JY. Am J Respir Crit Care Med 2002;165:867–903.
Warren DK, Shukla SJ, Olsen MA, et al. Crit Care Med 2003;31:1312–7.
Sources of funding: Department of Veterans Affairs and National Institutes of Health.
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1 University of Kent, Durrell Institute for Conservation Ecology, Marlowe Building, CT2 7NR, Canterbury, Kent, England.
2 Current address: Benemérita Universidad Autónoma de Puebla, Instituto de Ciencias, Departamento Universitario para el Desarrollo Sustentable, 14 Sur 6301, Colonia San Manuel, Ciudad Universitaria, 72570 Puebla, Puebla, México.
3 University of Queensland, School of Biological Sciences, Brisbane St Lucia, QLD 4072 Queensland, Australia.
Areas with high vegetative diversity tend to be threatened by habitat fragmentation and other human disturbances (Myers, 1988). This is serious because fragmentation diminishes biodiversity (Collinge et al., 2003), given that species composition on a patch will depend on its size and isolation (Crooks, 2002). Some of the negative effects of disturbances that have been reported are the following: soil fertility loss and erosion (Wezel and Rath, 2002), less vegetative (Nikiema, 2005) and fauna diversity (Blaum et al., 2007), favoring the establishment of invasive species (McDougall and Turkington, 2005) and brush encroachment (Van Auken, 2000), amongst others.
In central Mexico, the information about such effects in arid regions is limited to records of specific impacts in small areas (e.g. Giordani, 2008; Parra et al., 2008). This kind of information is necessary in the semi-arid area of Cerro Colorado that, being adjacent to the Tehuacán-Cuicatlán Biosphere Reserve, can be considered as highly biodiverse (Fig. 1). The region is highly heterogeneous, with more than 26 vegetation assemblages that can be grouped in tropical shrubland, as well as oak and pine forest (Valiente-Banuet et al., 2000). This area is important to conservation given its potential to serve as corridor for many species (Ramírez-Bravo, 2010). However, it is exposed to strong human pressure, with activities such as livestock grazing (Giordani, 2008), wood cutting (Pérez-Negrón and Casas, 2007), and extraction of non-timber products such as fruits (González-Soberanes and Casas, 2004; Pérez-Negrón and Casas, 2007; Parra et al., 2008). Although these activities have been considered to have low environmental impact, Pérez-Negrón and Casas (2007) suggested that, in some communities, cactus fruit collection can total 151 kg/year and wood extraction for fuel can be more than 400 tons/year. Therefore, these activities have the potential to shift species diversity and composition resulting in direct species loss (Osem et al., 2002) or favoring the establishment of invasive species, either exotic or native (Valéry et al., 2004; Blaum et al., 2007) that could be used as indicator species.
Figure 1: Map of the study area, showing the Tehuacán-Cuicatlán Biosphere Reserve and Cerro Colorado.
The main goal of this study was to develop a simple disturbance index that could be used in the area, as well as to determine the existence of indicator species that will allow quick conservation assessments. For this, we used species that have been recorded as indicators of human disturbances and that are known to encroach upon arid areas such as Acacias (Blaum et al., 2007) and Mimosas (Legesse, 2010).
In southeast Puebla, located in central Mexico, our study area known as Cerro Colorado is adjacent to the Biosphere Reserve "Tehuacán-Cuicatlán" (Fig. 1). It has an area of 224.25 km2, with a centroid in the coordinates 18°27'54"N, 97°18'58"W. It has different mountain ranges, with elevations between 600 and 2950 m asl that allow great habitat diversity. Despite the variety of vegetation association in the region, the National Forestry Inventory (SEMARNAP, 2001) identifies three main habitat types, which include tropical dry forest, shrubland, and oak and pine forest. Very distinct from its dry season, its wet season occurs from May to October and has an average precipitation of 250 to 500 mm. Its temperature ranges between 18 and 22 ºC (Botello et al., 2006).
We selected six study sites using a modified methodology based on Taki et al. (2007), where a hexagon is drawn in the center of a patch with the same vegetation type within the heterogeneous matrix using the vegetation map available from the National Commission for Knowledge and Use of Biodiversity (CONABIO). Each patch covered an area of 103 923 m2 and the minimum distance left between study sites was 2.5 km2. We coded each site according to nearby populations: three representing tropical dry forest (CM: Corral Macho, SB: San Esteban and SAC: San Antonio Cañada), and three from xeric shrubland patches (SD: San Diego, AJ: Ajalpan and VA: Colonia del Valle). Due to its restricted distribution in Cerro Colorado (less than 10%) (Bolaños-Bautista, 2011), as well as security problems by delinquent groups in these areas, oak and pine forest patches were not considered.
We determined which activities were undertaken in Cerro Colorado based on bibliographical review, informal interviews with people in nearby areas and observation of activities during fieldwork. We evaluated disturbance considering ten different activities, which have been reported to be affecting natural resources in the area (Table 1). Following Espinosa et al. (2011), we visually evaluated each variable and gave it a value between zero and three depending on the activity intensity in each patch (Table 2). Disturbance values were obtained through the addition of the ten variables without giving difference to the impact of each variable (e.g. fruit collection vs. hunting), because the aim of the index is to be as simple as possible to be used by local communities for quick assessments. In order to differentiate between conserved and disturbed environments, we divided the maximum score of 30 in three categories: low disturbance, when it had values ranging between zero and ten; medium disturbance, with values between 11 and 20; and high disturbance, with scores between 21 and 30.
Table 1: Principal disturbances and their examples in the Tehuacán-Cuicatlán Valley.
Table 2: Activities used to obtain the disturbance index and categorization of each value.
We conducted fieldwork during May-June 2011, as trees and shrubs are easier to count during this period. We characterized vegetation in 10 quadrats of 100 m2 in each of the six previously selected study sites by using a grid over the hexagon. This area covers 10% of each vegetation patch, which is considered as the minimum recommended area to determine species presence (Sánchez-Lalinde and Pérez-Torres, 2008). Vegetation characterization was based on trees and shrubs due to their relation with other species distribution such as carnivores (Palomares, 2001), and because they represent the principal vegetation component in this kind of habitat (Valiente-Banuet et al., 2000). We identified to genera and if possible to species level using specialized guides for the area (Guízar Nolazco and Sánchez Velez, 1991; Águilar and García, 2004; Téllez Valdés et al., 2008; Huerta Zamacona et al., 2009).
To determine if the sampling effort was sufficient, we generated an accumulation curve using tree and shrub species from the different study sites using the statistical software EstimateS (Colwell, 2006). Next, all data was grouped to determine the sampling effort (number of quadrats) per vegetation type (i.e. shrubland and tropical dry forest), per disturbance level (i.e. high, medium, and low), and for the study area (i.e. Cerro Colorado). We calculated species richness or the number of species present in an area; its evenness, which indicates how equal a community is; as well as its Shannon diversity index, which considers the number of species and how evenly they are distributed (Moreno, 2001). These indices were determined using Diversity add-inn (SSC, 2012) for Excel, and compared using an ANOVA between the different patches using Statistica (Statistica, 1999).
As in some cases identification was not possible to species level, we decided to use genera for further analysis except for Compositae and two shrub species that could not be identified and were grouped as Compositae and shrubs respectively. To determine similarities in species composition we used a nonparametric analysis of similarities test (ANOSIM) using the VEGAN software package, version 2.0-2 (Oksanen et al., 2011). This is a randomization-based analysis analogous to ANOVA, which builds a resemblance matrix that compares the species compositions of the sample groups of high and low disturbance (Ross, 2011). Results are indicated by R, which takes values between -1 and 1, where -1 indicates a random grouping while 1 indicates highest similarity. R is significant when its values are significantly different from zero. To find potential indicator species of low and high disturbance, we analyzed the similarity percentage (SIMPER) for tree species in both areas using the software PAST (Hammer et al., 2001). SIMPER is a nonparametric analysis that identifies how much species contribute to differences within groups (Clark and Warwick, 2001).
As the interest of this study was to identify possible indicator species of disturbance along the observed gradient, we calculated species abundance per disturbance in each vegetation patch (high, medium and low in shrubland; and high, medium and low in tropical dry forest). We considered especially trees and arborescent shrubs as they are severely affected by anthropogenic factors (Pérez-Negrón and Casas, 2007; Hernández Hernández et al., 2010). As a consequence, differences in species composition and abundance should indicate conservation. Analysis was carried out at the genus level. The genera Acacia Mill. and Mimosa L. were also considered in the analysis because their encroachment capacity has been well documented (Van Auken, 2000). We conducted further analysis using Mexican oregano (Lippia graveolens Kunth), as well as the shrubs Cnidoscolus tehuacanensis Breckon and Mimosa luisana Brandegee, in order to determine their possible use as disturbance indicator species.
where nij indicates the number of individuals of species i in patch j, and Nj represents the total number of individuals recorded in patch j.
Differences between disturbance levels were calculated using an ANOVA (Statistica, 1999). If results were significant, post hoc comparisons were made using a Tukey HSD test.
Activities recorded for the area ranged from food collection and hunting to mineral extraction activities. On the one hand, some of the activities are considered seasonal, occurring during specific times of the year; these include collection of fruits from different cacti species (Pavón and Briones, 2001), insects (Acuña, 2010), and plants for commerce (Dávila, 2003), as well as hunting. On the other hand, timber extraction occurs throughout the year for cooking and construction as well as grazing and hiking. Patches were classified according to the value obtained from adding the perceived level of the activity in the area (Table 3).
Table 3: Patch classification according to disturbance level, scores vary according to the perceived disturbance. 1=low, 2=medium, 3= high. Patches were classified according to the score value, with the conserved or low disturbance sites those having scores of less than ten, medium conserved or disturbed sites the ones with scores up to 20 and disturbed sites those with a score of more than 20. CM, SB and AJ indicate patches of tropical dry forest while SD, VA and SAC indicate shrubland patches.
Accumulation curves showed that sampling effort was not sufficient to determine overall plant diversity in Cerro Colorado (Fig. 2). Conversely, when considering the vegetation class "trees", the accumulation curves showed that sampling effort was sufficient to account for tree diversity in the area (Fig. 3). A list of the species that were identified in 60 quadrats can be found in Table 4. Tropical dry forest had more species than shrubland. When considering species richness between "high", "medium", and "low" disturbance areas; the species richness index (F=3.50, df=5,54, p<0.01) and evenness index (F=3.50, df=5,54, p<0.01) showed significant differences (Table 5), while the Shannon index (F=2.27, df=5,54, p=0.06) did not.
Figure 2: Species accumulation curves using Mau Tau (Colwell, 2006) for shrubland and tropical dry forest (TDF) in Cerro Colorado. Data corresponds to 30 quadrats sampled on each vegetation type.
Figure 3: Species accumulation curve using Mau Tau (Colwell, 2006) for Cerro Colorado considering all the species found in the 60 vegetation quadrats.
Table 4: List of principal species that were found in 60 quadrats surveyed in the six study sites in Cerro Colorado, grouped according to vegetation type. Identification was carried out with Guízar Nolazco and Sánchez Velez (1991); Aguilar Santelises and García (2004); Téllez Valdés et al. (2008) and Huerta Zamacona et al. (2009).
Table 5: Comparison of vegetation quadrats made in each patch: Shannon index, species richness and species evenness given as average with standard deviation. Below, the ANOVA statistics, species richness and evenness are significant, with a difference among VA and CM.
Despite similarity in vegetation richness among the vegetation patches, the ANOSIM analysis determined a significant difference between high disturbance and low disturbance areas in both vegetation types (shrubland global R=0.546, P<0.05; tropical dry forest global R=0.78, P<0.05). The SIMPER analysis of trees in Cerro Colorado identified four genera (out of 16 considered) that explained the top 50% of the compositional dissimilarity between high and low disturbance areas (Table 6). Of these, three genera (Parkinsonia L., Bursera Jacq. ex L., Thevetia L.) had greater average abundance in low disturbance quadrats and one genus (Ipomoea L.) in the high disturbance quadrats (Fig. 4).
Table 6: Species contributing to the top 50% of dissimilarity in species composition between the high and low disturbance areas in tropical dry forest and shrubland, and Cerro Colorado ordered by proportional contribution. The table indicates results using all morphospecies and just tree genera. Contribution and cumulative values are given in %. For Cerro Colorado, results indicate just tree genera.
Figure 4: Abundance of tree genera (bars) in shrubland vs. tropical dry forest in Cerro Colorado. The graph shows those genera that accounted for 50% of dissimilarity in genus composition between vegetation types, as identified by SIMPER analysis.
When considering the 46 species present in tropical dry forest, the SIMPER analysis identified eight groups (shrubs, Thevetia peruviana K. Schum., Hechtia podantha Mez, Compositae, Mimosa luisana Brandegee, columnar cacti, Opuntia spp., and Lippia graveolens Kunth) that explain the top 50% of the compositional dissimilarity between high and low disturbance areas. Five taxa (Mimosa luisana, Columnar cacti, Compositae, Lippia graveolens, and Hechtia podantha) had a higher average abundance in high disturbance areas. In contrast, in low disturbance areas three groups (shrubs, Thevetia peruviana, and Opuntia spp.) presented higher average abundance. When considering trees in tropical dry forest (14 genera), four genera (Thevetia, Acacia, Parkinsona and Bursera) explained all the dissimilarity between high and low disturbance areas. Three of these genera (Thevetia, Acacia and Bursera) had a higher average abundance in low disturbance quadrats (Fig. 5).
Figure 5: Abundance of tree genera in high disturbance vs. low disturbance in tropical dry forest in Cerro Colorado. The graph shows those genera that accounted for 50% of dissimilarity in genus composition between disturbance types, as identified by SIMPER analysis.
When considering the 37 taxa present in shrubland, just four (Agave spp., Hechtia podantha, Opuntia spp., and Lippia graveolens) explained differences between high and low disturbance areas. When considering the class tree within shrubland (11 taxa), only two taxa (Ipomoea and Parkinsonia) explained the top 50% of the compositional dissimilarity; where just one tree (Parkinsonia) had a higher mean abundance in low disturbance areas (Fig. 6).
Figure 6: Abundance of tree genera in high disturbance vs. low disturbance in shrubland in Cerro Colorado. The graph shows those genera that accounted for 50% of dissimilarity in genus composition between disturbance types, as identified by SIMPER analysis.
Cerro Colorado had two species that could be used as indicators of places with high and low disturbance levels. The shrubs Mimosa luisana (F=5.68, df=2,56, p<0.05) and Cnidoscolus tehuacanensis (F=3.19, df=2,56, p<0.05) presented higher relative abundance in quadrats with high disturbance levels in comparison to those presenting medium and low disturbance levels. As for the tropical dry forest, three genera were significantly different: Acacia (F=3.77, df=2,27, p<0.05); Ceiba Mill. (F=12.55, df=2,27, p<0.05) and Cnidoscolus Pohl (F=4.41, df=2,27, p<0.05), being present in higher densities in low disturbance quadrats. As for shrubland, medium disturbance quadrats had three taxa that are significantly more abundant than in other quadrats: the tree Tecoma stans (L.) Juss. ex Kunth (F=3.38, df=2,26, p<0.05), the shrub Mimosa luisana (F=5.16, df=2,26, p<0.05), and the genus Acacia (F=3.77, df=2,26, p<0.05). On the other hand, Mexican oregano (Lippia graveolens) (F=4.08, df=2,26, p<0.05) was less abundant in medium disturbed patches. Finally, the shrub Cnidoscolus tehuacanensis (F=5.72, df=2,26, p<0.05) was present in higher numbers in high disturbance quadrats.
Our results show that tropical dry forest in the area is more diverse than shrubland (40 vs. 26 taxa). Conversely, other studies based on a regional scale have found that shrubland is more diverse than tropical dry forest (Valiente-Banuet et al., 2000). We suggest these differences could be due to higher alpha diversity (site richness) in tropical dry forest at local level but higher beta diversity (richness in all patches) in shrubland at regional level. Furthermore, high species richness in semi-arid environments have been linked with species facilitation processes (Espinosa et al., 2011). However, in our area it seems to be more related with higher humidity levels and more microhabitats for plants (Murphy and Lugo, 1986). This has been documented for other taxa in the region such as mycorrhizal species (Camargo-Ricalde and Esperón-Rodríguez, 2005), and carnivores (Ramírez Pulido and Martínez Vázquez, 2007).
Our results show that there are significant differences between the quadrats surveyed when considering richness and evenness, but not for the Shannon index. The Tukey test revealed only a difference between CM and VA (Table 3). The latter could be due to insufficient sampling effort, despite the fact we covered the recommended area (10%) to identify plant diversity (Sánchez-Lalinde and Pérez-Torres, 2008).
The disturbance index proved useful for determining disturbance level among the different sampling areas in a simplistic manner. This study assumed that an additive approach to assessing the impact of different disturbances would be appropriate. However, it is necessary to generate an index considering the relationships and intensity of each variable with disturbance levels as they have a varied influence when generating changes in species diversity and composition. Furthermore, it has been recorded how some disturbances can have a long term effect over the environment changing original plant species composition and abundance (Espinosa et al., 2011; Ross, 2011) and in some cases favoring plant establishment (Hawkes and Flechtner, 2002; Ross, 2011). Examples include goat grazing and wood extraction, both of which have a stronger effect over habitat composition than other factors such as littering or hiking due to their capacity to alter plant communities over long periods of time as has been documented in other habitats in North America (Ripple and Beschta, 2008). Additionally, several plants that act as nurse plants (Castillo Landero and Valiente-Banuet, 2010) or create resource islands (Camargo-Ricalde et al. 2002) in the region are heavily exploited (Pérez-Negrón and Casas, 2007), which can promote long-term effects over species compositions.
In the case of the Tehuacán-Cuicatlán Valley, species of the genera Mimosa and Prosopis L. have been documented to create resource islands (Camargo-Ricalde et al., 2003) and to function as nurse plants (Castillo-Landero and Valiente-Banuet, 2010). However, they are heavily consumed by goats, which are also considered as good dispersers for both species (for Prosopis, Baraza and Valiente-Banuet, 2008, and for Mimosa, Giordani, 2008). This in turn promotes that disturbed environments especially by grazing increase densities of both genera resulting in an increase in shrub density.
Our results indicate that it is possible to select some species as indicators of disturbance due to a difference in their presence along the landscape. For instance, some genera that are used for wood extraction have a higher abundance in low disturbance areas in tropical dry forest (Thevetia, Ceiba, Acacia and Parkinsonia) and low disturbance in shrubland (Parkinsonia) (Paredes-Flores et al., 2007) compared to quadrats with high disturbance levels. With high disturbance, exploited species have changed their abundance (Willis et al., 2003). On the other hand, we found that two shrubs, Cnidoscolus tehuacanensis and Mimosa luisana, occurred in high numbers in disturbed quadrats in Cerro Colorado. In other areas, Mimosa luisana and other species from the same genera are known to be prone to encroachment (Legesse, 2010). The shrub Cnidoscolus tehuacanensis reacted different when data were analyzed by vegetation patch. In tropical dry forest C. tehuacanensis was more abundant in low disturbance areas, while in shrubland it was found more abundant in high disturbance levels. Hence, our results suggest that both species could be appropriate as disturbance indicator species in the area while for low disturbance levels, the genera Thevetia, Ceiba and Bursera could be used in tropical dry forest and Parkinsonia in shrubland. However, further sampling is necessary to determine the effectiveness of each genus.
This study shows the responses of two vegetation types present in the region along a disturbance gradient with varied activities that go from fruit collection to agricultural practices. The disturbance index used herein could be useful for community management and quick assessments in the area when they need an assessment for activities such as tourism as the index is easy to apply and calculate. It is proposed that goat grazing and fruit collection can have more long term impact over the species composition as previously thought; hence, conservation plans undertaken in the area need to integrate human activities to ensure long term functionality.
To cite as: Ramírez-Bravo, O. E. y L. Hernández-Santin. 2016. Plant diversity along disturbance gradient in a semi-arid ecosystem in Central Mexico. Acta Botanica Mexicana 117: 11-25.
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The often observed chilliness or rigors which buy triamterene 75 mg fast delivery pulse pressure 15, in the majority of cases immediately follow labor discount 75 mg triamterene amex arrhythmia foods to avoid, have been noticed in but few cases. These rigors, little account of which can be found in textbooks, are nothing more or less than surgical shock. He believes that as phosphorus and strychnine are remedies used in the treatment of rachitis with good results they are indicated during the gestation of the rachitic fetus. A wide field of action is open to this compound, as prostration from real deficiency of the nerve elements, prominent among which is phosphorus, is a common condition among very many, especially among brain workers. The strychnia lifts the forces up to the normal point, and the phosphorus permanently holds them there by its restorative influence. Administration— The dose is from the 1/ to 1/ of a grain, usually 200 50 administered in pill form. In granules of 1/ of a grain the agent is 120 convenient of administration and prompt in its action. Specific Symptomatology—Hale says arsenic acts upon the glandular system, and fluids of the body, while strychnine acts upon the nervous system. He advises it where the nutritive and glandular systems are involved to any great extent, with implication of the nervous system at the same time. This is found in paresis or mild forms of paralysis with edemic tissues, sodden, relaxed muscular structures, with anemia and tendency to dropsical conditions; great nervous weakness or prostration, with marked blood dyscrasia, chronic glandular induration, chronic ulceration, and the conditions of the mucous surfaces of the intestinal canal following typhus or typhoid fever and dysentery. It is specifically indicated in the debility or nerve failure of the aged, and in the prostrating influence of severe disease in children. During severe fevers it will not antagonize the sedative influence of the antipyretics, but will brace the nervous system against the prostration that will follow when the fever is gone. In spasmodic affections it Ellingwood's American Materia Medica, Therapeutics and Pharmacognosy - Page 428 is valuable. The author has given it persistently with sedative remedies in severe chronic cases of asthmatic bronchitis, especially in the aged, and cured them both permanently. It is indicated in a general way where strychnine is demanded, but has a special characteristic tonic influence. It may be given in the asthenic stage of all prostrating diseases, except during the hours of the day when the temperature is increasing or stationary at its highest point. It increases or intensifies the action of many stimulating, restorative or antiperiodic remedies.
Under this condition order triamterene 75mg free shipping hypertension bp, the reaction force at the base of support can- cels the force of gravity and the torque produced by it discount 75mg triamterene visa hypertension teaching for patients. If the center of mass is outside the base, the torque produced by the weight tends to topple the body (Fig. The wider the base on which the body rests, the more stable it is; that is, the more difficult it is to topple it. The same amount of angular displacement of a narrow-based body results in a torque that will topple it (Fig. Similar considerations show that a body is more stable if its center of gravity is closer to its base. The act of balancing requires maintenance of the center of gravity above the feet. A person falls when his center of gravity is displaced beyond the position of the feet. When carrying an uneven load, the body tends to compensate by bend- ing and extending the limbs so as to shift the center of gravity back over the feet. This tendency of the body to compensate for uneven weight distribution often causes problems for people who have lost an arm, as the continuous compen- satory bending of the torso can result in a permanent distortion of the spine. It is often recommended that amputees wear an artificial arm, even if they cannot use it, to restore balanced weight distribution. Let us calculate the magnitude of the force applied to the shoulder that will topple a person standing at rigid attention. In the absence of the force, the person is in stable equilibrium because his center of mass is above his feet, which are Section 1. When the person topples, he will do so by pivoting around point A—assuming that he does not slide. The counterclockwise torque Ta about this point produced by the applied force is Ta Fa × 1. The person is on the verge of toppling when the magnitudes of these two torques are just equal; that is, Ta Tw or Fa × 1. This shifts the center of gravity away from the pivot point A, increasing the restoring torque produced by the weight of the body.
It has been suggested to play a major role in the uptake of amphipathic organic anions by the choroid plexus from the cerebrospinal fluid (84) and also to mediate the intestinal uptake of fexofenadine (88) cheap 75mg triamterene with mastercard arrhythmia low blood pressure, while the role of Oatp1a5 in the brain capillaries remains to be elucidated buy triamterene 75mg with amex nqf 0013 hypertension. It is expressed in the sinusoidal membrane on the hepatocytes (108) and brush border membrane in the small intestine (109). In the kidney, it is mainly expressed in the basolateral membrane of the proximal tubules, and functional analysis elucidated that it accepts digoxin and T3 as substrates (111). Oct1 is localized to the sinusoidal membrane of the hepatocytes surrounding the central vein and basolateral mem- brane in the kidney (115,116). Com- parison of substrate recognition between Oct1 and Oct2 was performed using a þ gene expression system. There was no difference in the transport activities of cimetidine, ranitidine, and famotidine by Oct1, while Oct2 efficiently transports cimetidine rather than ranitidine and famotidine (120). Oct3 is ubiquitously expressed in normal tissue with low level, and, among them, gonads (testes and ovaries), placenta, and uterus exhibited relatively high expression (119). Oat1 is predom- inantly expressed in the kidney, where it is localized in basolateral membrane of the proximal tubules (130). The kidney expression is markedly higher in female rats than in male rats with similar hepatic expression (136,137), whereas the hepatic expression exhibits gender difference in mice, high in female and almost absent in male (138), although a controversial result was also obtained (139). Functional analyses of Oat2 elucidated that it exhibits substrate specificity similar to Oat1 (141), and accepts nonsteroidal anti-inflammatory drugs, such as salicylate, ketoprofen, and indomethacin as substrate (141–143). Oat2 has been suggested to be involved in the uptake of indomethacin and ketoprofen by rat hepatocytes (142,143). Rat Oat3 is expressed in the kidney, liver, eye, and brain (144), while its human counterpart is detected predominantly in the kidney (145,146). In rat brain, Oat3 is expressed in brain capillaries and choroid plexus, where it is localized on the abluminal and brush border membranes of the brain capillaries and choroid plexus epithelial cells, respectively, and accounts for the uptake of hydrophilic organic anions (81,147–150). In addition, it accepts some cationic compounds, cimetidine, ranitidine, and famoti- dine (144,150), which have been known as bisubstrate and recognized by both organic anion and cation transporters (153).
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HFCWO is defined by extra-thoracic oscillations generated by forces external to the respiratory system (Warwick 1991). External chest wall oscillations are applied using an inflatable vest around the torso which is either battery operated (Fig. 1) or is attached to a machine (Fig. 2) which vibrates at variable frequencies and intensities, as set by the operator, to ensure the individual's comfort and associated concordance.
This type of device is also called the Vest because the interface between machine and patient is a custom made vest through which the oscillations travel. The "Vest" is not commonly used in Australia. This relates partly to the cost, and the weight (around 8 kg).
There is some evidence based literature on the Vest and it is worth considering in individual circumstances related to lung pathology and those with co-morbidities.
HFCWO uses positive and negative pressure changes to augment peripheral and tracheal mucus movement towards the airway opening (Gross & King, 1984). Air pulses are transmitted to the vest at a high frequency increasing oscillatory chest wall compressions. During inflation the pressure increases to between 5 and 20 cm H2O causing a short burst of expiratory flow of up to 1.6L/second. The device usually operates between 2 and 25Hz.
It is thought that secretion mobilization is enhanced by the use HFCWO by increasing the air-liquid sheer forces during expiration. Another theory is that displacement of the airway walls may disengage secretions and enhance the effect of air-liquid flow. HFCWO is also thought to enhance ciliary beating and change the tenacity of bronchial secretions, making them less thick and therefore easier to expectorate (Hansen & Warwick, 1990).
To purchase The Vest or Afflovest.
HFCWO allows the patient to receive treatment to a large portion of their lung in a variety of modified postural drainage positions. It can be also done in sitting, thereby eliminating issues associated with reflux and certain modified positions.
HFCWO can be administered by a physiotherapist, appropriately trained carer, or the patient themselves, allowing the potential for independent treatment.
Can combine HFCWO therapy with a mucolytic inhalation and intersperse every 5 minutes with periods of either PEP therapy and huffing and coughing to clear the mucus.
A program can be set up whereby the frequency and pressure is adjusted approximately every 5 minutes or as indicated to assist with sputum movement from the peripheral to the more central airways.
large pleural effusion or empyema.
HFCWO has been found to be safe and have variable efficacy in children (over the age of 7yrs) and adults with mild to moderate cystic fibrosis in an exacerbation during the hospitalisation phase and at home during the maintenance phase ((Darbee, Kanga, & Ohtake, 2005), (Kempainen et al., 2010), (Oermann, Swank, & Sockrider, 2000), (Osman, Roughton, Hodson, & Pryor, 2010).
Sputum clearance with HFCWO is reported to be similar to PEP therapy (Braggion et al 1995) however other authors report that it is less effective than ACBT (Pike et al 2004).
A more recent study long term study comparing PEP therapy and HFCWO found a significant difference in terms of number of pulmonary exacerbations and time to first pulmonary exacerbation, in favour of PEP mask therapy. The author concluded that the use of the HFCWO as a primary airway clearance in children with CF should not be supported (McIlwaine et al 2013).
There is currently no evidence for the use of this device for children with non-CF bronchiectasis.
Although HFCWO devices are not readily available in Australia, many other airway clearance options available that are cheaper and highly effective.
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This combination doubles your energy and sets new standards in the application of advanced energy in the operating room.
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The New THUNDERBEAT Type S with Intelligent Tissue Monitoring allows for the targeted and efficient application of energy for optimal temperature control to achieve maximum safety in surgery.
The THUNDERBEAT Open Extended Jaw provides versatility, speed, and precision. It has been designed to make it highly suitable for the requirements of open surgical procedures.
Using the combined energy types of the THUNDERBEAT SEAL & CUT mode simultaneously allows for safe coagulation and fast tissue transection. Fewer vessel-ligation steps are required due to the ability of pre-coagulation as well as due to the secure cutting and sealing of 7 mm vessels.
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1.Safety and efficacy of new integrated bipolar and ultrasonic scissors compared to conventional laparoscopic 5-mm sealing and cutting instruments. Seehofer et al. Surg Endosc. 2012 Sep;26(9):2541-9. doi: 10.1007/s00464-012-2229-0. Epub 2012 Mar 24.
2.Pilot study of pulmonary arterial branch sealing using energy devices in an ex vivo model. Liberman et al. J Thorac Cardiovasc Surg. 2014 Dec;148(6):3219-23. doi: 10.1016/j.jtcvs.2014.05.089. Epub 2014 Jul 19.
4.Evaluation of the safety, efficacy, and versatility of a new surgical energy device (THUNDERBEAT) in comparison with Harmonic ACE, LigaSure V, and EnSeal devices in a porcine model. Milsom et al. J Laparoendosc Adv Surg Tech A. 2012 May;22(4):378-86. doi: 10.1089/lap.2011.0420. Epub 2012 Feb 24.
5.A prospective trial evaluating the clinical performance of a novel surgical energy device in laparoscopic colon surgery. Milsom et al. Surg Endosc. 2015 May;29(5):1161-6. doi: 10.1007/s00464-014-3783-4. Epub 2014 Aug 27.
6.TransOral endoscopic UltraSonic Surgery (TOUSS): a preliminary report of a novel robotless alternative to TORS. Fernández et al. Eur Arch Otorhinolaryngol. 2015 Dec;272(12):3785-91. doi: 10.1007/s00405-014-3423-6. Epub 2014 Dec 16.
7.Evaluation of Vessel Sealing Performance Among Ultrasonic Devices in a Porcine Model. Tanaka et al. Surg Innov. 2015 Aug;22(4):338-43. doi: 10.1177/1553350615579730. Epub 2015 Apr 7.
8.Thermal injury of the recurrent laryngeal nerve by THUNDERBEAT during thyroid surgery: findings from continuous intraoperative neuromonitoring in a porcine model. Kwaket al. J Surg Res. 2016 Jan;200(1):177-82. doi: 10.1016/j.jss.2015.06.066. Epub 2015 Jul 6.
9.Comparison of the harmonic focus and the thunderbeat for open thyroidectomy. Van Slycke et al. Langenbecks Arch Surg. 2016 Sep;401(6):851-9. doi: 10.1007/s00423-016-1448-6. Epub 2016 May 25.
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Purpose. The aim of this study was to compare the results of ultrasound (US), whole-body scintigraphy with iodine-131 (I-131 WBS) and positron emission tomography with fluorine-18 deoxyglucose (FDG-PET) in the follow-up of patients after thyroidectomy for differentiated thyroid carcinoma (DTC). Materials and methods. Thirteen patients (3 men, 10 women) were evaluated by neck US, I-131 WBS and FDG-PET. In each patient six anatomical regions (right and left thyroid bed, right and left cervical region, right and left supraclavicular region) were investigated, for a total of 78 regions. Distant metastases were investigated by I-131 WBS and FDG-PET and considered separately in the analysis. Imaging findings were compared with the reference standards, such as fine-needle aspiration cytology (2), biopsy (4) or clinical-radiological studies (7). Results. US, FDG-PET and I-131 WBS showed concordant negative results in most (70, 90%) of the anatomical sites considered. In one patient with left cervical lymph node metastasis, the imaging techniques showed concordant positive results (1%). In the remaining 7 regions (9%), the imaging results were discordant; in particular, tumour lesions, nodal metastases (4) and thyroid bed recurrences (3) were detected by US only (3), by US and I-131 WBS (1) and by FDG-PET only (3). With regard to distant metastases, FDG-PET and I-131 WBS yielded concordant negative results in the majority (77%) of patients (9); in one patient only were the two imaging techniques concordant in their positive result. In the last three patients, the results were discordant; in particular, distant metastases were detected by I-131 WBS only in two patients and by FDG-PET only in one patient. Conclusions. Our work indicates a fundamental role for US in evaluation of the neck after surgery for DTC. WBS is useful to determine differentiation of tumour lesions, to identify thyroid remnants and to look for distant metastases. FDG-PET has an important role in cases of dedifferentiated thyroid carcinoma in which WBS and thyroglobulin measurements are unable to detect tumour lesions. © 2008 Springer-Verlag.
201 Records (186 escludendo Abstract e Conferenze).
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Honolulu Oil Corp., operator for the Antelope Shale Zone Unit, Buena Vista Hills, initiated a program for oil well acid treatment for the purpose of removing precipitated carbonate scales from production equipment and for well stimulation, Oct. 23, 1956. This program was active through Feb., 1958. In this period 35 wells were acid treated yielding a net increase in oil of 1,390 B/D and gas increase of 3,265 Mcf/D. The total cost of acidizing the 35 wells was $80,000.
Acid stimulation of California oil wells has been used to a limited extent, primarily for dissolving precipitated carbonate scales and other plugging agents within or adjacent to the wellbore.
In the Antelope Shale Zone in Buena Vista Hills, some producing wells showed evidence of rapid carbonate scale precipitation on the tubing and rods in early phases of production. Observation of this scale led to the belief that acid treatment of a well might be beneficial both to production equipment and to production rate, if liner and adjacent wellbore were suffering plugging. Initial application of acid to an oil well was made almost solely to clean up production equipment.
The Buena Vista Hills field is located in Kern County near Taft. The field is on a large anticlinal structure including two domes and containing several productive sands from about 2,300 to 3,900 ft, and also containing the Antelope Shale Zone which is predominantly a fractured shale. The shallower sand zones were developed over a period from 1909 to the present time. The fractured shale zone has been developed in the last six years and development is still progressing to a minor degree. This report is confined to the East Dome. The upper sands have been acid treated on occasion over a period of years in a spotty manner giving spotty results. A few jobs were quite beneficial, but the majority were of moderate or no success. The predominant basis for treatment of these upper sands was also the observation of precipitated scale on production equipment.
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I am a psychiatrist with 15 years of experience and a holistic approach. I completed specialist training in working with children, adolescents and young adults and have a specialist interest in the psychotherapy of children and adults. I am interested in the scientific truth and my patients' unique experiences.
I work with children, adolescents and adults with a wide range of mental health difficulties including depression, anxiety, phobias, OCD, eating difficulties, body dysmorphic disorder, trauma, identity confusion, relationship difficulties, Autistic Spectrum Disorders and ADHD. I am approved to carry out specialist diagnostic tests including the ADOS (Autism Diagnostic Observation Schedule). I work both as an independent consultant psychiatrist and as an honorary consultant psychiatrist at Tavistock Clinic.
I provide individualised treatment and support, taking into account the latest evidence from medical research. I have expertise in psychotherapies, pharmacotherapy and parenting approaches. My training includes psychoanalytic psychotherapy, family therapy, cognitive behavioural therapy, mentalisation based treatment, specialist parenting programmes. I am also interested in the influence of nutrition and environmental factors on child development and mental health.
I undertook trainings at Institute of Psychiatry, Tavistock Clinic and Anna Freud Centre. I studied medicine in Istanbul Medical School whilst completing psychiatry and neurology studies at Harvard and Northwestern Medical Schools. I completed core psychiatric training at Chelsea and Westminster and Royal Free Hospitals working with patients across all age groups. I completed higher psychiatric training in child and adolescent psychiatry at Guy's and Maudsley Hospitals. I worked as a consultant psychiatrist in community adolescent and neurodevelopmental teams at Central North West London NHS Foundation Trust. I then attended adult medical psychotherapy training at the Tavistock Clinic.
My experience involves working across inpatient, outpatient and day hospital settings with patients from all age groups. I worked in generic child mental health teams and also National & Specialist mental health teams including eating disorders, adolescent forensic, neurodevelopmental disorders and paediatric liaison teams.
I have an academic interest in the field. I have done research on eating disorders at the Institute of Psychiatry looking at comorbid disorders such as depression and anxiety with eating disorders and on neuropsychiatric conditions such as Huntington's and Alzheimer's Diseases at Harvard and Northwestern Medical Schools in the USA. I also work as the lead child psychiatrist at a charity called New Beginnings which aims to provide treatment to the traumatised and disadvantaged children in Turkey. I regularly mentor young doctors and therapists. I give public education seminars on child and adolescent and women's mental health and write articles for journals and social media.
I am a member of the Royal College of Psychiatrists, Independent Doctors Federation and the Association for Child and Adolescent Mental Health.
I speak English and Turkish.
Co-author of the chapter on psychiatry in the book; 'Diagnosis and Treatment, Nobel Publications, ISBN 975-420-291-5.
Medical Students' Attitudes and Behaviours on Alcohol Consumption, E Caglar, Journal of Dependence, August 2003, 4;2, ISSN 1302-5570.
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Central to the integrative treatment of the brain as an organ of very high metabolic demand, is the development and expansion of a modelling platform that can handle, in an anatomically accurate, patient specific manner, the transport and interplay of blood and cerebrospinal fluid with the parenchyma – the neuronal and astrocyte tissue that constitutes the functioning brain.
The focus of this work package is to lead and contribute to the development of a simulation platform capable of representing, for the first time, the transport processes in the cerebral environment in their entirety and in a coupled manner. This involves the expansion of an existing proven conceptual framework – that of multicompartmental poroelasticity. It accounts for anatomically derived, healthy and diseased, cases that are utilised for equipping VPH-DARE@IT with realistic, experimentally-derived, micro-laws of transport, absorption and regulation in the cerebral environment.
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Gastro-esophageal acid reflux or GERD for short can be treated with a traditional Westernized medical angle using the chemical approach or you can use a treatment with more of a holistically angle using a nutritional approach.
According to guidelines established by the American College of gastroenterology, GERD is defined as "symptoms or mucosal damage produced by the abnormal reflux of gastric contents into the esophagus".
In searching for the right GERD treatment or cure it's important you not get confused by elusive medical lingo. Simply put GERD is your heartburn gone wild. What was a simple case of acid indigestion has been allowed to inflame into a bad case of burned throat tissue.
Thanks to television programming, direct-to-consumer advertising and mass media propaganda millions of people end up using treatment that turn their heartburn into GERD.
If millions of people were addressing the root cause of their acid indigestion and heartburn in the first place, instead of popping antacids, then you and millions of others wouldn't be even asking what GERD treatment they should use.
Why? Because there wouldn't be any GERD and if there were they would be rare cases. GERD treatment is a huge business that sells antacid products, proton pump inhibitor chemicals and ultimately surgery and the maintenance products for that.
Your heartburn was never intended to lead you down a sales funnel of gimmicks and gadgetry . . . GERD treatment is a product made by the medical industry that you want to avoid at all costs.
GERD treatment is a gateway for laparoscopic or fundoplication surgery as a protocol to help you avoid the inevitable throat cancer you're likely to get if you continue to just use GERD treatments to cover symptoms.
Before you even buy another bottle of antacids or fill that GERD treatment prescription for Proton Pump Inhibitor chemicals (PPIs), do yourself a favor, find a physician that is willing to give you a stomach acid test.
One of the biggest scams of GERD treatment is selling people on chemically blocking stomach acid production, when in fact their GERD symptoms are from a lack of stomach acid.
Don't just take my word for it, look into it yourself. What I found is GERD treatment leads to acid rebound, which is a chemical dependency on PPIs . . .
Whenever you use a treatment, whether for GERD or acid reflux, whatever it is, keep in mind that treatment is only blocking symptoms . . . the root cause of your GERD is still there.
That's why the nutritional approach is a smart avenue to look into before falling into the GERD treatment trap.
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CLA or Conjugated Linoleic Acid closely resembles Linoleic acid, a necessary fatty acid found in vegetable oils that the body requires to work in tandem and balance with the fats found in fish oils. Benefits from CLA include possible enhancement of immunity, as well as potential protection from cancer and heart disease. CLA may also stimulate growth of muscle tissue while promoting fat loss according to a number of human studies.
Patients suffering from advanced congestive heart failure exhibited significantly improved heart function after supplementing with Ubiquinol, according to a recent clinical trial. In the first clinical trial evaluating Ubiquinol effects on dangerous late-stage congestive heart failure, cardiologist Peter Langsjoen found that critically ill patients who supplemented with Ubiquinol for just three months experienced a 24 to 50 percent increase in their hearts' ability to pump blood. In some cases, the patients' plasma level of CoQ10, which is key to overall heart health, more than tripled.
Mice given Quercetin, a naturally occurring substance found in small amounts in healthy fruits and vegetables including garlic, blueberries, green tea, broccoli and red wine, were less likely to contract the flu. The study also found that stressful exercise increased the susceptibility of mice to the flu, but Quercetin canceled out that negative effect. Quercetin, a Catechin flavonoid has been shown to have anti-viral properties in cell culture experiments and animal studies, with this the first study specifically looking at the flu.
People with lower levels of vitamin D in their blood may be at greater risk of developing type 2 diabetes according to researchers from the National Public Health Institute in Helsinki, Finland. The research found that men with the highest serum vitamin D levels were the least likely to develop type 2 diabetes 22 years later. Lack of vitamin D interferes with insulin secretion, and studies suggest a link between low vitamin D and diabetes the scientists note.
Olive Leaf Extract may help reduce blood pressure levels, according to an interesting human study from Israel. Twenty pairs of identical twins with elevated blood pressure were split and one from each pair was given either 500mg or 1000mg of Olive Leaf Extract daily and the other given inactive placebo. Within an eight week period the twin from each pair that received the 1000mg Olive Leaf Extract experienced reduced systolic and diastolic blood pressure by 11 and 5 mmHg, respectively.
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Usually, when we have bouts of dizziness it is easy to think that it will pass, but what happens when your dizziness is recurring? It can be scary, debilitating, and confusing. Nearly 90 million Americans suffer from dizziness- but not all of those people are receiving treatment in the form of Physical Therapy. Choosing a specialized type of Physical Therapy called Vestibular Therapy can change the lives of dizziness sufferers. Simply put- Vestibular Therapy is a specialized form of therapy designed to alleviate primary and secondary problems caused by the vestibular system.
How do you know if dizziness is affecting your daily life?
Specialized Vestibular Therapy sessions can help you regain your sense of balance.
Balance therapy can help improve your daily life activities like work or self-care.
Your program is individualized. Each exercise is hand-selected by your therapist based on your level of dizziness or imbalance.
Doing balance exercises with a Physical Therapist can greatly decrease your risk of falling.
Your therapist can properly diagnose your vertigo and create a treatment plan based on your needs.
You are in a safe, controlled, and supervised environment when in the treatment area- this means that you can be confident that you're getting the support you need during therapy sessions.
We work together to rebuild your confidence and get you back to your life!
If this sounds like something you'd benefit from, it's time to stop suffering and consider Vestibular Therapy! The benefits of this specialized form of therapy can truly change your life and get you back to living without the fear of dizziness or falling.
You can find and schedule available appointments with Peak Performance Physical Therapy and hundreds of other quality physical therapy clinics on the BetterPT website and BetterPT mobile app. You can now see a physical therapist without a prescription from a doctor via direct access and can start receiving care and get BETTER faster. Get out of the dizziness "fog" and start feeling better today!
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Cannabidiol, also known as CBD, is a natural cannabidiol compound of the Cannabis plant, derived from an organic substance which Cannabis secretes naturally.
Cannabis, along with hemp, is related to marijuana. Cannabis is the genus from which hemp and all forms of marijuana develop. There are more than 60 cannabidiol compounds in Cannabis, and until recently, the most studied was THC (delta-9 tetrahydrocannabinol) found abundantly in marijuana and responsible for its psychoactive effect.
CBD is the second most abundant cannabidiol in Cannabis plants and has no psychoactive effects, which contributed to its legalization. CDB's noted beneficial impact on health has resulted in significant scientific study and recent media coverage.
We derive our CBD products from hemp, not marijuana, and can also be referred to as CBD-rich hemp oil, hemp extracts, cannabis oil rich in CBD or "hemp extracts," since typically they contain ingredients in addition to CBD.
CBD oil is not the same as hemp seed oil and organic hemp oil. These products are derived from hemp seeds, which do not contain CBD.
All our hemp crops are grown legally in the United States and subject to rigorous quality-control standards for purity and cannabidiol content.
Studies show the endocannabinoid system keeps a range of body systems in balance.
When you encounter a stressor in daily life, your body produces a surge of stress-related chemicals such as cortisol and adrenaline. These increase your heart rate, respiration and alertness levels to help you deal with the stressful situation. Once the tension has passed, your body begins to rebalance.
The endocannabinoid system regulates the release of neurotransmitters that return your body to homeostasis and keeps it there, awaiting the next stressor trigger.
The endocannabinoid system is made up receptors in cells of organs and tissues throughout your body, including your brain and immune cells. Cannabidiol helps your body communicate internally during the return to homeostasis, and regulate the natural processes that produce a balanced state.
Benefits of CBD
Natural relief for chronic pain due to neuropathic (nervous system) damage. No harmful side effects.
Help prevent the molecular damage caused by free radicals by slowing cellular oxidation.
BRAIN CELLS
Helps modulate neural cell production; may aidstroke, head injury & cerebral ischemia recovery.
Reduces anxiety, assists in restful sleep, overall mood improvement from reduced pain.
Helps moderate inflammatory responses in autoimmune diseases such as arthritis, lupus, Crohn's, psoriasis.
NEUROLOGICICAL
Anti-psychotic and anti-depressive effects, antiseizure and anti-nausea properties.
CELLULAR IMPACT
Helps inhibit spread of malignant and abnormal cell growth; aids receptivity to chemotherapy.
NOT A "HIGH"
CBD Oil may not contain THC greater than .03%, the psychoactive ingredient of cannabis but not enough to give you a "high". It is safe and legal.
CBD's long history
The pharmaceutical industry is beginning to reposition itself regarding CBD's homeopathic potential to improve health. Studies and research about how this natural remedy can help us with problems in our health in a effective way.
CBD is a legal, non-psychoactive product and should not be confused with THC, the psychoactive compound in marijuana which produces its intoxicating effect. CBD has no psychoactive effects.
What conditions can CBD address?
The National Institute of Health says CBD can help reduce the symptoms of many conditions such as these, listed alphabetically:
Abuse of Substances / Withdrawal
Irritation in nerves
More than 90% of people with questions find their answers here.
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2019 Game Log | Main Player Page
Date vs Score AB R H 2B 3B HR RBI TB BB K SB CS HBP OBP SLG Avg
7/16/19 TB 8-3 3 0 0 0 0 0 0 0 0 2 0 0 0 .340 .491 .262
7/14/19 TOR 4-2 4 0 1 0 0 0 0 1 0 1 0 0 0 .344 .500 .267
7/7/19 @ TB 1-2 4 1 2 1 0 1 1 6 0 1 0 0 0 .342 .494 .261
7/3/19 @ NYM 5-1 3 0 0 0 0 0 0 0 1 1 0 0 0 .332 .462 .251
6/30/19 @ BOS 12-8 4 1 2 0 0 0 1 2 1 1 0 0 0 .334 .470 .253
6/29/19 @ BOS 17-13 4 2 1 0 0 1 3 4 1 1 0 0 0 .330 .469 .250
6/24/19 TOR 10-8 4 1 0 0 0 0 1 0 0 0 0 0 0 .333 .470 .253
6/23/19 HOU 4-9 2 1 1 0 0 0 0 1 1 0 0 0 0 .338 .477 .256
6/20/19 HOU 10-6 3 0 1 0 0 0 0 1 1 0 0 0 0 .334 .474 .254
6/19/19 TB 12-1 4 0 1 0 0 0 0 1 0 1 0 0 0 .332 .476 .253
6/16/19 @ CHW 10-3 4 2 2 0 0 0 4 2 0 0 0 0 0 .330 .479 .251
6/15/19 @ CHW 8-4 1 2 0 0 0 0 0 0 3 0 0 0 0 .325 .479 .247
6/14/19 @ CHW 2-10 2 0 0 0 0 0 0 0 0 2 0 0 0 .320 .481 .248
6/11/19 NYM 4-10 4 1 2 0 0 1 1 5 0 0 0 0 0 .323 .476 .250
6/11/19 NYM 12-5 3 1 2 0 1 0 1 4 1 0 0 0 0 .320 .464 .246
6/10/19 NYM 0-0 0 0 0 0 0 0 0 0 0 0 0 0 0 .314 .453 .241
6/9/19 @ CLE 7-6 5 1 1 0 0 1 2 4 0 0 0 0 0 .314 .453 .241
6/5/19 @ TOR 7-11 4 1 0 0 0 0 0 0 0 0 0 0 0 .325 .459 .249
6/4/19 @ TOR 3-4 4 0 0 0 0 0 0 0 0 1 0 0 0 .330 .467 .253
6/2/19 BOS 5-8 4 0 0 0 0 0 0 0 0 1 0 0 0 .335 .476 .258
5/31/19 BOS 4-1 2 1 1 0 0 0 0 1 1 0 0 0 0 .341 .488 .263
5/29/19 SD 7-0 3 0 1 0 0 0 1 1 0 1 0 0 1 .337 .488 .260
5/26/19 @ KC 7-8 1 0 0 0 0 0 0 0 0 1 0 0 0 .336 .481 .257
5/23/19 @ BAL 6-5 4 0 1 0 0 0 0 1 0 2 0 0 0 .333 .474 .250
5/20/19 @ BAL 10-7 3 1 1 0 0 0 0 1 1 0 0 0 0 .324 .457 .239
5/15/19 BAL 3-1 1 0 0 0 0 0 0 0 0 0 0 1 0 .322 .446 .234
5/12/19 @ TB 7-1 1 0 1 0 0 0 1 1 0 0 0 0 1 .330 .459 .241
5/9/19 SEA 3-1 4 1 0 0 0 0 0 0 0 1 1 0 0 .342 .478 .248
5/5/19 MIN 4-1 2 1 0 0 0 0 0 0 1 0 0 0 0 .347 .464 .252
5/1/19 @ ARI 2-3 5 0 1 0 0 0 0 1 0 0 0 0 0 .352 .479 .261
4/30/19 @ ARI 1-3 4 0 1 0 0 0 0 1 0 1 0 0 0 .356 .489 .263
4/28/19 @ SF 11-5 4 0 0 0 0 0 0 0 1 2 0 0 0 .359 .496 .263
4/27/19 @ SF 6-4 3 0 0 0 0 0 0 0 1 1 0 0 0 .364 .512 .271
4/25/19 @ LAA 5-11 4 1 1 0 0 0 1 1 1 0 0 0 0 .370 .528 .280
4/24/19 @ LAA 6-5 4 0 0 0 0 0 0 0 0 0 0 0 0 .369 .537 .281
4/21/19 KC 7-6 5 1 3 0 0 0 0 3 0 0 0 0 0 .365 .537 .278
4/14/19 CHW 2-5 4 0 0 0 0 0 0 0 0 1 0 0 0 .343 .495 .264
4/10/19 @ HOU 6-8 5 1 1 0 0 1 1 4 0 0 0 0 0 .366 .506 .278
4/9/19 @ HOU 3-6 3 1 0 0 0 0 0 0 1 1 0 0 0 .375 .486 .284
4/7/19 @ BAL 15-3 3 2 1 1 0 0 0 2 3 0 0 0 0 .392 .530 .303
4/6/19 @ BAL 6-4 5 1 1 1 0 0 0 2 0 1 0 0 0 .370 .524 .302
4/3/19 DET 1-2 0 0 0 0 0 0 0 0 0 0 0 1 0 .365 .537 .296
3/25/19 @ WAS 3-5 2 0 1 1 0 0 0 2 0 0 0 0 0 .450 .697 .394
3/22/19 PHI 6-3 3 0 0 0 0 0 0 0 1 1 0 0 0 .444 .690 .379
3/18/19 @ ATL 7-4 3 1 1 0 0 0 0 1 0 0 0 0 0 .467 .800 .440
3/15/19 BOS 14-1 2 0 1 0 0 0 1 1 0 0 0 0 1 .480 .900 .450
3/12/19 BAL 8-7 2 2 1 0 0 1 2 4 1 0 0 0 0 .526 1.000 .438
3/10/19 PIT 6-5 3 0 2 0 0 0 0 2 0 1 0 0 0 .500 .857 .429
3/6/19 STL 5-9 3 0 1 0 0 0 0 1 0 1 0 0 0 .500 1.125 .375
3/3/19 DET 7-1 2 2 2 0 0 2 2 8 0 0 0 0 0 .571 1.600 .400
3/1/19 BAL 2-2 2 0 0 0 0 0 0 0 0 0 0 0 0 .250 .000 .000
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:: Table of Contents
October-December 2016
Online since Thursday, October 20, 2016
Full text access is free in HTML pages; however the journal allows PDF access only to subscribers.
Full text in EPub is free except for the current issue. Access to the latest issue is reserved only for the paid subscribers.
Quality research in Indian medical colleges and teaching institutions: The need of the hour p. 213
MS Tullu, S Karande
Temporal variability of readmission determinants in postoperative vascular surgery patients p. 216
MJ Lin, F Baky, BC Housley, N Kelly, E Pletcher, JD Balshi, SP Stawicki, DC Evans
Introduction: Clinical information continues to be limited regarding changes in the temporal risk profile for readmissions during the initial postoperative year in vascular surgery patients. We set out to describe the associations between demographics, clinical outcomes, comorbidity indices, and hospital readmissions in a sample of patients undergoing common extremity revascularization or dialysis access (ERDA) procedures. We hypothesized that factors independently associated with readmission will evolve from "short-term" to "long-term" determinants at 30-, 180-, and 360-day postoperative cutoff points. Methods: Following IRB approval, medical records of patients who underwent ERDA at two institutions were retrospectively reviewed between 2008 and 2014. Abstracted data included patient demographics, procedural characteristics, the American Society of Anesthesiologists score, Goldman Criteria for perioperative cardiac assessment, the Charlson comorbidity index, morbidity, mortality, and readmission (at 30-, 180-, and 360-days). Univariate analyses were performed for readmissions at each specified time point. Variables reaching statistical significance of P< 0.20 were included in multivariate analyses for factors independently associated with readmission. Results: A total of 450 of 744 patients who underwent ERDA with complete medical records were included. Patients underwent either an extremity revascularization (e.g. bypass or endarterectomy, 406/450) or a noncatheter dialysis access procedure (44/450). Sample characteristics included 262 (58.2%) females, mean age 61.4 ± 12.9 years, 63 (14%) emergent procedures, and median operative time 164 min. Median hospital length of stay (index admission) was 4 days. Cumulative readmission rates at 30-, 180-, and 360-day were 12%, 27%, and 35%, respectively. Corresponding mortality rates were 3%, 7%, and 9%. Key factors independently associated with 30-, 180-, and 360-day readmissions evolved over the study period from comorbidity and morbidity-related issues in the short-term to cardiovascular and graft patency issues in the long-term. Any earlier readmission elevated the risk of subsequent readmission. Conclusions: We noted important patterns in the temporal behavior of hospital readmission risk in patients undergoing ERDA. Although factors independently associated with readmission were not surprising (e.g. comorbidity profile, cardiovascular status, and graft patency), the knowledge of temporal trends described in this study may help determine clinical risk profiles for individual patients and guide readmission reduction strategies. These considerations will be increasingly important in the evolving paradigm of value-based healthcare.
A case–control study of epidemiological factors associated with leptospirosis in South Gujarat region p. 223
KT Desai, F Patel, PB Patel, S Nayak, NB Patel, RK Bansal
Background: The current study was planned to identify the epidemiological factors associated with leptospirosis in South Gujarat region using neighborhood controls. Methods: A total of 100 cases of leptospirosis occurred in South Gujarat region during the year 2012 were selected using simple random sampling. Three neighbors of the selected cases formed the controls (n = 300). A pretested structured questionnaire was used for data collection and data were analyzed using Epi Info 2007. Results: There was significant association of illiteracy (odds ratio [OR] =1.82, 95% confidence interval [CI] =1.14–2.89), working in waterlogged fields during the reference season (OR = 4.6, 95% CI = 1.6–17.9), swimming/bathing in canals, open air defecation practices, storage of cow dung in or surrounding house, residence in the house made up of cow dung walls, households with access of food to rodents, injuries over hands/foot during the endemic season (OR = 3, 95% CI = 1.8–4.8), and history of skin disease during the endemic season (OR = 4.2, 95% CI = 2–8.5), with leptospirosis. Only 10% of individuals had gumboots for protection. A total of 83 (83%) cases and 240 (80%) controls had taken oral doxycycline chemoprophylaxis (P > 0.05). Cases had taken chemoprophylaxis for a median 4 weeks (range: 1–8) while controls had taken the same for median 8 weeks (range = 1–8) (P < 0.002). Conclusions: Although the commonly established factors appear to be associated with leptospirosis, the role of host factors seems to play a more important role in determining susceptibility to leptospirosis in exposed individuals.
An appropriately performed conventional blood culture can facilitate choice of therapy in resource-constrained settings-comparison with BACTEC 9050 p. 228
PV Surase, G Nataraj, K Pattamadai, PR Mehta, AR Pazare, MC Agarwal, RN Nanavati
Aims: Comparison of conventional blood culture with BACTEC 9050 for rate and time to detection of microorganisms. Settings and Design: A prospective study was carried out in a multispecialty tertiary care teaching hospital. Subjects and Methods: A total of 835 paired specimens (797 blood and 38 nonblood specimens) were collected and processed according to standard microbiological procedures by both conventional method as well as by BACTEC 9050 automated culture system. Clinical details of patients were recorded. Data were analyzed for time to detection and isolation rate by the two systems and compared. Results: Overall culture positivity for BACTEC 9050 and the conventional system was 32% and 19.88%, respectively. Eighty-five demonstrated concordant growth, 136 specimens were culture positive by BACTEC only, and 38 specimens were culture positive by conventional only. Twelve contaminants in BACTEC and nine contaminants in conventional system were detected. Using BACTEC 9050, higher isolation was observed for Acinetobacter spp., coagulase negative Staphylococcus spp., Streptococcus spp., and Candida spp. A total of 410 patients were on antimicrobial treatment and culture positivity was significantly higher with BACTEC 9050 (P < 0.0001). There was a significant difference in the mean time to detection with BACTEC 9050 recovering 86.8% of isolates within 48 h (P < 0.0001). Conclusions: Although BACTEC 9050 demonstrated a significantly higher recovery of microorganisms from blood, an appropriately performed conventional blood culture can facilitate the choice of therapy.
Chest radiographic manifestations of scrub typhus p. 235
KPP Abhilash, PR Mannam, K Rajendran, RA John, P Ramasami
Background and Rationale: Respiratory system involvement in scrub typhus is seen in 20–72% of patients. In endemic areas, good understanding and familiarity with the various radiologic findings of scrub typhus are essential in identifying pulmonary complications. Materials and Methods: Patients admitted to a tertiary care center with scrub typhus between October 2012 and September 2013 and had a chest X ray done were included in the analysis. Details and radiographic findings were noted and factors associated with abnormal X-rays were analyzed. Results: The study cohort contained 398 patients. Common presenting complaints included fever (100%), generalized myalgia (83%), headache (65%), dyspnea (54%), cough (24.3%), and altered sensorium (14%). Almost half of the patients (49.4%) had normal chest radiographs. Common radiological pulmonary abnormalities included pleural effusion (14.6%), acute respiratory distress syndrome (14%), airspace opacity (10.5%), reticulonodular opacities (10.3%), peribronchial thickening (5.8%), and pulmonary edema (2%). Cardiomegaly was noted in 3.5% of patients. Breathlessness, presence of an eschar, platelet counts of <20,000 cells/cumm, and total serum bilirubin >2 mg/dL had the highest odds of having an abnormal chest radiograph. Patients with an abnormal chest X-ray had a higher requirement of noninvasive ventilation (odds ratio [OR]: 13.98; 95% confidence interval CI: 5.89–33.16), invasive ventilation (OR: 18.07; 95% CI: 6.42–50.88), inotropes (OR: 8.76; 95% CI: 4.35–17.62), higher involvement of other organ systems, longer duration of hospital stay (3.18 ± 3 vs. 7.27 ± 5.58 days; P< 0.001), and higher mortality (OR: 4.63; 95% CI: 1.54–13.85). Conclusion: Almost half of the patients with scrub typhus have abnormal chest radiographs. Chest radiography should be included as part of basic evaluation at presentation in patients with scrub typhus, especially in those with breathlessness, eschar, jaundice, and severe thrombocytopenia.
Utility and limitations of multiplex ligation-dependent probe amplification technique in the detection of cytogenetic abnormalities in products of conception p. 239
D Saxena, M Agarwal, D Gupta, S Agrawal, V Das, SR Phadke
Background and Introduction: Chromosomal abnormality is found in about half of first-trimester abortions. Karyotype is the gold standard to detect chromosomal abnormalities. Multiplex ligation-dependent probe amplification (MLPA) offers advantage over karyotype in terms of lower failure rate, faster turnaround time, and much higher resolution than conventional karyotyping and found to be 98% concordant with conventional karyotype. Aim: We performed this study to look for the utility of MLPA in diagnosing chromosomal abnormalities in first-trimester abortions. Materials and Methods: MLPA using subtelomeric SALSA probe sets (P036 and P070) was used to detect cytogenetic abnormalities in products of conception in missed/spontaneous abortions. Results: A total of ninety abortus samples were analyzed by MLPA. Successful results were provided in (67) 74.4% of the cases while no conclusion could be drawn in 25.6% (23) of the cases. Fifty-five (82.1%) cases were cytogenetically normal and 17.9% (12) had some abnormality. Aneuploidy was detected in 8 (66.7%) cases, 3 (25%) had double-segment imbalance, and one (8.3%) had partial aneuploidy. Conclusion: We suggest that MLPA is a good substitute to traditional karyotype.
Can angiotensin-converting enzyme inhibitors impact cognitive decline in early stages of Alzheimer's disease? An overview of research evidence in the elderly patient population p. 242
K Rygiel
Alzheimer's disease (AD) is a neurodegenerative disease, in which an accumulation of toxic amyloid beta in the brain precedes the emergence of clinical symptoms. AD spectrum consists of presymptomatic, early symptomatic, and symptomatic phase of dementia. At present, no pharmacotherapy exists to modify or reverse a course of AD, and only symptomatic treatments are available. Many elderly patients, diagnosed with multiple medical conditions (such as cardiovascular diseases, Type 2 diabetes mellitus, and cerebrovascular diseases) are at increased risk of the development of mild cognitive impairment (MCI), AD, and vascular dementia. Studies have revealed reduced rates of cognitive decline, in elderly patients, who were treated with centrally active angiotensin-converting enzyme inhibitors (ACE-Is) (that have an ability to cross the blood–brain barrier). This article reviews recently published literature, focused on possible protective influence of the centrally active ACE-Is, in the elderly population, at risk for cognitive decline.
The mysterious Zika virus: Adding to the tropical flavivirus mayhem p. 249
B Mishra, B Behera
Until now, known as the demure cousin of dengue virus (DENV) inhabiting Africa, Zika virus (ZIKV) has reinvented itself to cause explosive epidemics captivating the Western hemisphere. The outbreak causing potential for ZIKV was realized when it made its way from Africa to Yap Island Micronesia in 2007, and in French Polynesia in 2013. From there, it moved on to Brazil in 2015. Now ZIKV has infected people in more than 33 countries in Central and South America and the Caribbean. Moreover the epidemiological and subsequent virological association with microcephaly cases in Brazil has prompted the World Health Organization to declare a public health emergency of International Concern. ZIKV shares not only its vector Aedes aegypti with dengue and chikungunya but also the geographic distribution and clinical features, which makes the laboratory confirmation mandatory for definitive diagnosis. The serological cross-reactivity with other Flavivirus, particularly with DENV makes laboratory confirmation challenging and will place additional burden on health systems to establish molecular diagnostic facilities. The evidence of additional nonvector modes of transmission, such as perinatal, sexual as well as transfusion has made preventative strategies more difficult. As ZIKV disease continues to mystify us with several unanswered questions, it calls for coordinated effort of global scientific community to address the ever growing arboviral threat to mankind.
Evolution of medical education in India: The impact of colonialism p. 255
Anshu , A Supe
The cross-cultural exchanges between the people of India and their colonial rulers provides a fascinating insight into how these encounters shaped medicine and medical education in India. This article traces the history of how Indian medicine was transformed in the backdrop of colonialism and hegemony. It goes on to show how six decades after independence, we have have still been unable to convincingly shrug off the colonial yoke. India needs to work out a national medical curriculum which caters to our country's needs. A symbiotic relationship needs to be developed between the indigenous and allopathic systems of medicine.
Wernicke's encephalopathy due to hyperemesis gravidarum: Clinical and magnetic resonance imaging characteristics p. 260
VV Ashraf, J Prijesh, R Praveenkumar, K Saifudheen
Hyperemesis gravidarum-induced Wernicke's encephalopathy (WE) is an underestimated condition. The purpose of this study is to improve its awareness and early diagnosis. We report five cases of WE secondary to hyperemesis gravidarum. Classic triad of encephalopathy, ataxia, and ocular signs was seen in four out of five patients. Two unusual features noted in this series were papilledema in one patient and severe sensory-motor peripheral neuropathy in one patient. Magnetic resonance imaging (MRI) was abnormal in all the five patients, and high signal in medial thalamus and surrounding the aqueduct was the most common abnormality (5/5). Involvement of caudate nucleus was seen in two patients with severe psychosis, and two patients had bilateral cerebellar peduncle involvement. Median time delay between onset of neurological symptoms and diagnosis was 7 days. All patients improved with thiamine, but minor sequelae were seen in four patients at 12 months follow-up. One patient had a fetal demise. Hyperemesis gravidarum-induced WE is a common cause of maternal morbidity. Typical MRI findings of symmetric medial thalamic and periaqueductal signal changes may permit a specific diagnosis. A delay in diagnosis, therefore treatment, leads to worse prognosis.
Stroke mimic: Perfusion magnetic resonance imaging of a patient with ictal paralysis p. 264
D Sanghvi, C Goyal, J Mani
We present an uncommon case of clinically diagnosed window period stroke subsequently recognised on diffusion – perfusion MRI as ictal paralysis due to focal inhibitory seizures or negative motor seizures. This case highlights the importance of MRI with perfusion imaging in establishing the diagnosis of stroke mimics and avoiding unnecessary thrombolysis.
Obturator hernia: An uncommon cause of small bowel obstruction p. 267
S Shreshtha
A 70 year old lady presented to surgery emergency with small bowel obstruction without any obvious etiology. On exploration she was found to have an obstructed obturator hernia, which is a rare pelvic hernia with an incidence of 0.07-1.4% of all intra-abdominal hernias. Diagnosis is often delayed until laparotomy for bowel obstruction. Strangulation is frequent and mortality remains high (25%). Early diagnosis and surgical treatment contributes greatly to reduce the mortality and morbidity rates. A variety of techniques have been described, however surgical repair has not been standardized. It is an important diagnosis to be considered in elderly patients with intestinal obstruction.
Relapsing-remitting chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids syndrome in association with P/Q-type voltage-gated calcium channel antibody p. 269
D Dubey, M Devine, K Blackburn, W Warnack
Maternal infection, malnutrition, and low birth weight p. 270
MP Roy
Prevalence of burnout and its correlates among residents in a tertiary medical center in Kerala, India: A cross-sectional study p. 271
MD Al-Mendalawi
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The pharmaceutical industry is under growing pressure to improve R&D productivity to sustain sufficient innovation to replace the loss of revenues due to patent expiration for successful products. Combined with the low number of new molecular entities (NMEs) entering into clinical phases, new screening strategies are demanded. Compounds fail for many reasons, but some are more avoidable such as poor oral bioavailability, pharmacokinetic properties or toxicity, and low margins of safety.
A new strategy to reduce attrition and maintain the number of NMEs entering clinical phases requires improving toxicity characterization at early stages of drug discovery combined with more efficient and cost-effective assays.
The zebrafish is emerging as a complement to existing in vitro technologies and established preclinical in vivo models that can be scaled for high-throughput. Technological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening.
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crashworthiness tests and proposes actions to improve crash safety features for future rotorcraft designs. by. Roy G. Fox. Bell Helicopter Textron. Crashworthiness is the ability of a structure to protect its occupants during an impact. This is The primary reason is that ejection or exiting a helicopter is impractical given the rotor system and typical altitude at which Army helicopters fly. In aeronautics, first structural design requirements for better crash protection were established for military helicopters and light fixed-wing aircraft. Also, for all.
Retrieved from " https: Crashworthiness is the ability of a structure to protect its occupants during an impact. Primary crash injuries were reduced, but secondary injuries within the cockpit continued to occur. Airbags were considered a viable solution to reducing the incidents of head strikes in the cockpit, and were incorporated in Army helicopters.
Pilots were receiving spinal injuries in otherwise survivable crashes due to decelerative forces on the spine and fires. Please help improve this article by adding citations to reliable sources. The history of human tolerance craswhorthiness deceleration can likely trace its beginning in the studies by John Stapp to investigate the limits of human tolerance in the s and s. As the US Army 's doctrine changed, helicopters became the primary mode of transportation in Vietnam.
This is commonly tested when investigating the safety of aircraft and vehicles. Crashworthiness may be assessed either prospectively, using computer models e.
ctashworthiness Depending on the nature of the impact and the vehicle involved, crashworthness criteria are used to determine the crashworthiness of the structure. You can help by adding to it. Several criteria are used to assess crashworthiness prospectively, belicopter the deformation patterns of the vehicle structure, the acceleration experienced by the vehicle during an impact, and the probability of injury predicted by human body models.
Transport safety Aviation accidents and incidents. This led to the consideration of additional protective devices such as airbags. A common injury criterion is the Head impact criterion HIC. This page was last edited on 5 Septemberat In the s and s, the Pakistan Army began serious accident analysis into crashworthiness as a result of fixed-wing and rotary-wing accidents.
Crashworthiness is assessed retrospectively by analyzing injury risk in real-world crashes, often using regression or other statistical techniques to control for the myriad of confounders that are present in crashes. The intent of this guide is to assist engineers in understanding the design considerations important to crash-resistant military aircraft.
Injury probability is defined using criteriawhich are mechanical parameters e. Webarchive template wayback links Pages using web citations with no URL Articles needing additional references from November All articles needing additional references Articles to be expanded from August All crashdorthiness to be expanded Articles using small message boxes.
This article needs additional citations for verification. Unsourced material may be challenged and removed. They have each developed their own authoritative safety requirements and conducted extensive research and development in the field. From Wikipedia, the free encyclopedia.
Work began to develop energy absorbing seats to reduce the chance of spinal injuries during training and combat in Vietnam. November Learn how and when to remove this template message.
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By profession I am a clinical psychologist and work in the field of mental health. I specialise in working with complex stress, personality disorders, additctions, self-harm, and suicide. I have a special interest in women's issues and sexuality. I have worked in both private and state organisations and have experience working with children and adults.
I am also an independent business woman and share some of my private work with my partner, so I have my own experience of having to self-motivate and self-regulate in an ever-increasing world of competition. I enjoy reading and writing and both edit and review books in my field regularly. I am also involved in training other psychologists and mental health professionals and see this as a vital part of my work.
Outside work I am a Mummy, partner, sister, daughter and friend. I am interested in music and sport and make the most of my down-time. Being a mother is an important aspect of my life and something that has brought with it many changes and realisations - there are so many things I just didn't get before I was a parent...especially about my own parents and their choices.
I take an interest in world affairs and have lived in Africa, Australia, Arabia and currently the UK. I have roots in Africa and am acutely aware of the importance of difference and how it can be a hinderance and a help.
Post-pregnancy bodies - learning to love the skin you're in!
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Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding
B. A. Gosnell, J. E. Morley, A. S. Levine
Food Science and Nutrition
Medicine - Administration
A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10-100 times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems.
Ketocyclazocine
Striatum
Fingerprint Dive into the research topics of 'Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding'. Together they form a unique fingerprint.
ketazocine Medicine & Life Sciences
Globus Pallidus Medicine & Life Sciences
Eating Medicine & Life Sciences
Opioid Analgesics Medicine & Life Sciences
Corpus Striatum Medicine & Life Sciences
Gosnell, B. A., Morley, J. E., & Levine, A. S. (1984). Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding. Physiology and Behavior, 33(3), 349-355. https://doi.org/10.1016/0031-9384(84)90153-7
Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding. / Gosnell, B. A.; Morley, J. E.; Levine, A. S.
Gosnell, BA, Morley, JE & Levine, AS 1984, 'Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding', Physiology and Behavior, vol. 33, no. 3, pp. 349-355. https://doi.org/10.1016/0031-9384(84)90153-7
Gosnell BA, Morley JE, Levine AS. Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding. Physiology and Behavior. 1984 Sep;33(3):349-355. https://doi.org/10.1016/0031-9384(84)90153-7
Gosnell, B. A. ; Morley, J. E. ; Levine, A. S. / Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding. In: Physiology and Behavior. 1984 ; Vol. 33, No. 3. pp. 349-355.
@article{752d2068aaa5432fa5370765a7d59309,
title = "Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding",
abstract = "A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10-100 times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems.",
keywords = "Feeding, Globus pallidus, Ketocyclazocine, Naloxone, Opiates, Striatum",
author = "Gosnell, {B. A.} and Morley, {J. E.} and Levine, {A. S.}",
T1 - Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding
AU - Gosnell, B. A.
AU - Morley, J. E.
AU - Levine, A. S.
N2 - A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10-100 times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems.
AB - A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10-100 times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems.
KW - Feeding
KW - Globus pallidus
KW - Ketocyclazocine
KW - Naloxone
KW - Opiates
KW - Striatum
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Doctors in Dubai : Best doctors in Dubai : Dubai doctor directory : Guide to medical specialists in Dubai. Find doctors in Dubai by medical specialties : Search a doctor in Dubai by doctor name, clinic, specialty, language, gender and location. Featuring doctor contact numbers, websites and from the best, reputable good clinics and hospitals in Dubai UAE. Everything you need to know! doctor reviews, ratings, analysis of top doctors & health practitioners in Dubai UAE.
Dr. Khaled completed his residency and fellowship training in Great Britain where he worked as an Eye Surgeon for ten years. He was the first Eye Surgeon to perform LASIK procedures in his country, and was also a pioneer in introducing Implantable contact lens surgery as well as laser cataract surgery and lately the first UltraLASIK procedures. He published a prize winning textbook on Corneal Diseases in Great Britain as well as more than one hundred papers and presentations in European and American Medical Journals.
Consultant, Ophthalmologist and Corneal Surgery Specialist.
Director of Cornea and Refractive Surgery Services.
Dr. Sharif received a fellowship degree from the Royal College of Physicians and Surgeons in Glasgow UK, specializing in eye surgery. One year later, he received a Fellowship Degree from the Royal College of Ophthalmologists in London. Dr. Sharif is also a consultant for Wavelight Excimer Laser Company (ALCON – USA ), and is involved in the training of other Surgeons in many countries on different Refractive Surgery Techniques. Dr. Sharif has published many articles on the "Diagnosis and Management of Eye Diseases" including a textbook on "Corneal Diseases" which was nominated for the prize of the best medical book published in Britain by the Society of British Authors.
Ophthalmologist technologists often are trained on the job in entry level positions. However, completing a degree program can definitely help those seeking a job in this field. For those who wish to work as techs, they will need to understand both visual disorders and also, how to help those who are visually impaired understand the treatment methods available to them.
A technologist in the field of ophthalmology may find himself or herself learning a wide range of things through both educational paths and through on the job training. This is an area of great growth potential, and typically those who do take entry level positions move up fairly steadily in both position and pay.
An ophthalmologist technologist will work with an optician to make and fill the prescriptions that their patients require. Depending on the severity of the visual disorder in question, this treatment may vary.
Ophthalmology is the field of medicine which deals with the diagnosis and treatment of disorders of the eye. As such, ophthalmology coding is the method of coding the diagnostic procedures for treatments pertaining to ophthalmology.
An important component of ophthalmology coding is the right use of modifiers. The wrong modifier can wreak havoc on your claims.
The branch of medical science which deals with the anatomy, particular diseases and physiological features of the eye is referred to as "Ophthalmology'. A doctor who is specialized in Ophthalmology is called an Ophthalmologist; Ophthalmologists are both medical and surgical specialists since they perform eye surgeries.
The term "Ophthalmology" is derived from the Greek terms 'ophthalmos' which means the eye and 'logia' which refers to study. It therefore quite literally is an exhaustive study of the anatomy of the eyes and the diseases which affect eyesight. The eyes of humans and those of the animal kingdom, surprisingly, have only minor differences although the functions of both are quite complex and some of the diseases that affect mankind also affect animals – e.g. cataract.
Reviews : Dr. Khaled Sharif Ophthalmologist Dubai. Ophthalmologist at Sharif Eye Center, Dubai Healthcare City,, Dubai, United Arab Emirates.
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BEERSE, BELGUIM, 11 Nov. 2016 – Janssen-Cilag International NV ("Janssen") announced today that the European Commission (EC) has approved the use of STELARA® (ustekinumab) for the treatment of adult patients with moderately to severely active Crohn's disease who have had an inadequate response with, lost response to, or were intolerant to either conventional therapy or a tumour necrosis factor alpha (TNFα) antagonist or have medical contraindications to such therapies.1 STELARA is the first biologic therapy for Crohn's disease that targets interleukin (IL)-12 and IL-23 cytokines, known to play a key role in inflammatory and immune responses.
"Today's decision is an important step forward for people living with Crohn's disease. There is a great need for alternative effective therapeutic options to help people control their symptoms, and STELARA offers a strong clinical dataset demonstrating high rates of clinical response and remission for those whom biologic therapy is appropriate," said Frederic Lavie, EMEA Therapeutic Area Leader Immunology, Cardiovascular and Metabolics, Janssen.
In the European Union, STELARA is approved for the treatment of moderate to severe plaque psoriasis in adults who failed to respond to, or who have a contraindication to, or are intolerant to other systemic therapies including ciclosporin, methotrexate or psoralen plus ultraviolet A (PUVA), and is also indicated for the treatment of moderate to severe plaque psoriasis in adolescent patients from the age of 12 years and older who are inadequately controlled by or are intolerant to other systemic therapies or phototherapies. In addition, STELARA is approved alone or in combination with MTX for the treatment of active psoriatic arthritis in adult patients when the response to previous non-biological disease-modifying antirheumatic drug (DMARD) therapy has been inadequate. In November 2016, the European Commission approved STELARA for the treatment of adult patients with moderately to severely active Crohn's disease who have had an inadequate response with, lost response to, or were intolerant to either conventional therapy or a TNF-alpha antagonist or have medical contraindications to such therapies.
The Janssen Pharmaceutical Companies of Johnson & Johnson maintain exclusive worldwide marketing rights to STELARA, which is currently approved for the treatment of moderate to severe plaque psoriasis in 87 countries, psoriatic arthritis in 71 countries and paediatric psoriasis in 34 countries.
This press release contains "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995 regarding the approval of a new indication. The reader is cautioned not to rely on these forward-looking statements. These statements are based on current expectations of future events. If underlying assumptions prove inaccurate or known or unknown risks or uncertainties materialize, actual results could vary materially from the expectations and projections of Janssen and/or Johnson & Johnson. Risks and uncertainties include, but are not limited to: uncertainty of commercial success; competition, including technological advances, new products and patents attained by competitors; challenges to patents; product efficacy or safety concerns resulting in product recalls or regulatory action; changes in behavior and spending patterns or financial distress of purchasers of health care products and services; changes to applicable laws and regulations, including global health care reforms; manufacturing difficulties and delays; and trends toward health care cost containment. A further list and description of these risks, uncertainties and other factors can be found in Johnson & Johnson's Annual Report on Form 10-K for the fiscal year ended January 3, 2016, including in Exhibit 99 thereto, and the company's subsequent filings with the Securities and Exchange Commission. Copies of these filings are available online at www.sec.gov, www.jnj.com or on request from Johnson & Johnson. None of the Janssen Pharmaceutical Companies or Johnson & Johnson undertakes to update any forward-looking statement as a result of new information or future events or developments.
4. Sandborn W, et al. DDW 2016:Abstract 768.
5. Kimball AB, et al. JEADV 2012:27(12):1535–1545.
6. Langley RG, et al. Br J Dermatol 2015:172(5):1371–1383.
8. EMA. Meeting highlights from the Committee for Medicinal Products for Human Use (CHMP). Summary of opinion 15 September 2016. Available at: http://www.ema.europa.eu/docs/en_GB/document_library/Summary_of_opinion/human/000958/WC500212877.pdf (last accessed November 2016).
9. FDA. Biologics License Application: Approval letter. 23 September 2016. Available at: http://www.accessdata.fda.gov/drugsatfda_docs/appletter/2016/761044Orig1s000ltr.pdf (last accessed November 2016).
10. World IBD Day. Home. Available at http://www.worldibdday.org/index.html (last accessed November 2016).
11. European Federation of Pharmaceutical Industries and Associations. Inflammatory Bowel Disease. Available at http://www.efpia.eu/diseases/78/59/Inflammatory-Bowel-Disease (last accessed November 2016).
12. Crohn's and Colitis UK. Crohn's disease. Available at http://www.crohnsandcolitis.org.uk/about-inflammatory-bowel-disease/crohns-disease (last accessed November 2016).
13. IBD Determined. IBD & Colorectal Cancer. Available at http://www.ibdetermined.org/ibd-information/ibd-complications/colorectal-cancer.aspx (last accessed November 2016).
14. Best WR, et al. Gastroenterol 1976;70(3):439–44.
15. Summary of Product Characteristics Stelara 45 mg solution. Janssen-Cilag International NV http://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Product_Information/human/000958/WC500058513.pdf (last accessed November 2016).
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Tetraethylammonium hydroxide
Currently viewing: 001 Key | Experimental result002 Key | Read-across (Structural analogue / surrogate)
short-term repeated dose toxicity: dermal
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Application of the substance was done with an Hill top Chamber® (Hill Top Biolabs, Inc., Cincinnati, OH, USA), exact size of exposure area is not given. No recovery group was included in this study to assess reversibility of the symptoms.
US EPA GLP Standards (40CFR Part 792)
Tetramethylammonium hydroxide (TMAH)
other: liquid
- Name of test material (as cited in study report): Tetramethylammonium hydroxide (TMAH)
- Substance type: aqueous solution (25%)
- Physical state: clear liquid
- Lot/batch No.: Run No. 10806113
- Specific density: 1.014 g/ml at 20°C
- Storage: in septum-capped containers at room temperature (appr. 22°C) under a hood
- Source: Charles River Laboratories, Portage, MI, USA
- Age at study initiation: appr. 5 weeks
- Weight at study initiation:76 - 139 g (random 15% of rats was weighed)
- Fasting period before study: yes, overnight prior to terminal sacrifice
- Housing: individually, in suspended stainless steel cages
- Diet: ad libitum, certified Purina rodent chow 5002 (PMI Feeds, Inc, St. Louis, MO, USA)
- Water: ad libitum, City of Chicago municipal water
- Acclimation period: ≥ 2 weeks
- Temperature (°C): 22.0 - 25.5
- Humidity (%): 27.3 - 69.0
- Air changes (per hr): not described
- Photoperiod (hrs dark / hrs light): 12/12
occlusive
Details on exposure:
- Area of exposure: Hill top Chamber® (Hill Top Biolabs, Inc., Cincinnati, OH, USA), occlusive
- Type of wrap if used: Chamber was secured with an elastic band secured with Velcro®
- Time intervals for shavings or clippings: 24 hours prior to treatment, three times/ week during the application period
- Washing (if done): no
- Amount applied (volume with unit): 1 ml/kg bw
- Concentration (if solution): 0%, 0.25%, 0.55%, 1%, 3%, 5%
- Constant volume used: yes
USE OF RESTRAINERS FOR PREVENTING INGESTION: yes, plastic neck collars
The concentration of TMAH in water formulations was determined by titration using HCl. All dosing formulation concentrations were confirmed in first two weeks of experiment and were within 3% of the theoretical concentration. The stability of the highest and lowest concentrations of the test dosing formulations was determined over 8 and 13-day periods. Both concentrations were still stable after 13 days.
6 hours/ day; 4 weeks
5 days/ week
Doses / concentrationsopen allclose all
Doses / concentrations 1
Dose / conc.:
2.5 mg/kg bw/day (actual dose received)
10 mg/kg bw/day (actual dose received)
yes, concurrent vehicle
50 mg/kg NaOH
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily on week days, once daily in weekends and holidays
DETAILED CLINICAL OBSERVATIONS: yes, at least weekly
DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations:
BODY WEIGHT: Yes
- Time schedule for examinations: one day pre-dosing, weekly during treatment and terminal body weight
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No
WATER CONSUMPTION: No
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: Yes
- Time schedule for collection of blood: on day of sacrifice
- Anaesthetic used for blood collection: Yes (sodium pentobarbital)
- Animals fasted: Yes, overnight (appr. 18 hours)
- How many animals: all surviving animals
- Parameters according to guideline (OECD 410, 1981) were examined.
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:on day of sacrifice
URINALYSIS: Yes
- Time schedule for collection of urine: overnight prior to scheduled sacrifice
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters examined: urine volume, levels of sodium and potassium, color, appearance, refractive index, specific gravity, microscopic evaluation, and qualitative measurement of glucose, urobilinogen, pH, protein, ketones, blood, nitrites, leukocytes, creatinine and bilirubin.
NEUROBEHAVIOURAL EXAMINATION: No
GROSS PATHOLOGY: Yes.
Complete necropsy was performed on all rats, gross necropsy was performed on the 5% TMAH rats or rats not surviving at least two days of TMAH exposure.
HISTOPATHOLOGY: Yes.
Tissues according to guideline were collected from rats that were designated for complete necropsy. A complete set of tissues from all rats in the vehicle control group and in the two highest surviving dose groups (3% and 1% TMAH) were examined microscopically.
In addition, the skins (application site) in the 0.55% and 0.25% TMAH groups were also examined.
Adrenals, brain, heart, kidneys, liver, ovaries, spleen and testes were weighed, and the organ to fasted body weight ratios were calculated.
On study days 2 and 24, blood samples for determination of acetylcholinesterase (AChE) activity were collected via the retroorbital sinus from anesthetized (70% CO2/30% air) rats at least two hours after application of dosing formulations.
Statistical analysis of continuous data was performed using analysis of variance followed, where appropriate, by Dunnett's test. All comparisons were performed using the vehicle control exposed animals as the control group. A minimum significance level of p≤0.05 was used for all comparisons.
effects observed, treatment-related
Description (incidence and severity):
Early clinical signs of the animals that died due to TMAH dose were hypoactivity, ptosis, ataxia, tremors, dyspnea and convulsions. No clinical signs at 2.5, 5.5 and 10 mg/kg bw/day.
Dermal irritation:
Treatment-related gross necropsy findings included various dermal irritation observations at the application skin site (ie thickened, pigmentation, scab/scaly) which increased in incidence with dose level.
mortality observed, treatment-related
Description (incidence):
All rats treated with 50 mg/kg/day died during the study and mortality was observed in 8 of 10 (males and females) in the rats treated with 30 mg/kg/day. Nine females and two male rats in the 50 mg/kg dose group died on day 1. All but one remaining male rats in the 50 mg/kg dose group died on days 2-3, one male and one female rat in this group died on Day 8. Two female rats in the 30 mg/kg dose group died on day 1, all other rats died between day 1 and 14, apart from two males and two females that survived treatment with 30 mg/kg TMAH. No other deaths were observed.
No significant differences in body weight were observed during the study apart from a significant decrease in mean body weight gain for the two surviving male rats in the group treated with 30 mg/kg/day in week 2. Their body weight had recovered at the end of the study.
A significant decrease in food consumption was observed during week 2 for the two surviving male rats in the group treated with 30 mg/kg/day. No significant differences were noted in any other test group.
A significant decrease in mean corpuscular hemoglobin concentration was observed in females treated with 10 mg TMAH/kg/day. However, this decrease was not considered toxicologically significant since the decrease was very small and no other parameters were affected.
At the 30mg/kg/day dose level, the two surviving male rats exhibited a significant increase in cholesterol (152 % of control) while the two surviving females exhibited a significant increase in total bile acids (212 % of control) .
Significant decreases in potassium levels were observed in the male exposed to 2.5 mg/kg/day and in both males and females in the group treated with 30 mg/kg/day. In addition, significant decreases in urine creatinine values were observed in the females treated with 10 and 30 mg/kg/day. No other significant differences were noted in the urine parameters.
effects observed, non-treatment-related
There were no significant differences in absolute or relative organ weights for any tissue weighed from male TMAH-treated rats. For female rats, a statistically significant increase in absolute organ weight was seen in the adrenals of the rats exposed to 30 mg/kg/day. However, this difference is based on a group size of the two surviving rats and was not considered treatment-related.
Red or dark pigmented lungs were generally early deaths and thus correlated with congestion. Pulmonary congestion was noted in the early deaths of the rats treated with 30 mg/kg/day. No other significant differences to the control group were found.
Necrosis at the application site was observed in 9 of 10 male rats and 8 of 10 females in the 30 mg/kg/day dose group. Necrosis was also noted in one rat/sex in the 10 mg/kg/day dose group, and in one female rat in the 5.5 mg/kg/day dose group. Other microscopic skin findings were exudative scab, squamous epithelial hyperplasia and inflammation (acute, subacute, or chronic active) at all dose levels, including controls. The magnitude of these findings increased in incidence, severity and distribution with increasing dose concentration of TMAH. Thymic lymphoid necrosis was observed in the group exposed to 30 mg/kg/day. The incidence of vacuolation in the liver was elevated in the males exposed to 30 mg/kg/day. The overall incidence of vacuolation was 1/10, 0/10 and 7/9 males and 6/10, 6/10 and 3/8 females in the control, 10 and 30 mg/kg/day dose groups resp. Vacuolation was accompanied with membrane bound homogenous, eosinophilic intracytoplasmic material. Hepatocellular eosinophilic intracytoplasmic material was present in 7/9 male rats and 2/8 female rats in the 30 mg/kg/day dose group. Individual hepatocyte necrosis was limited to only 3/9 male rats in the 30 mg/kg/day dose group.
Acetylcholinesterase (AChE) activity in plasma and red blood cells was not inhibited in TMAH-treated rats compared to the vehicle controls on days 2 or 24.
10 mg/kg bw/day
other: TMAH
other: Thymic lymphoid necrosis, hepatocyte vacuolation with eosinophilic , intracytoplasmic material, hepatocyte necrosis pulmonary congestion at 30 mg/ kg bw/ day.
2.5 mg/kg bw/day
histopathology: non-neoplastic
other: Other microscopic skin findings were exudative scab, squamous epithelial hyperplasia and inflammation (acute, subacute, or chronic active) at all dose levels, including controls.
Lowest effective dose / conc.:
haematopoietic
Organ:
Treatment related:
Dose response relationship:
Relevant for humans:
An extra acute study addressing the cause of mortality was included in this report. In both male and female rats treated with a single dose of 250 mg/kg TMAH a significant decrease in pH and an increase in pCO2 in the blood was observed. The males also had a decreased HCO3 levels, while male and female rats treated with a single dose of 50 mg/kg bw TMAH only had decreased PO2 levels. Corresponding hematology profiles indicated an increase in hemoglobin in the 25% TMAH-treated males and an increase in mean corpuscular volume in the 25% TMAH-treated females as well as increases in mean corpuscular hemoglobin in the 5% and 25% TMAH-treated females. Alterations in erythrocyte morphology were noted in both sexes in each of the test substance treatment groups, but not in all animals and not in a consistently dose-related fashion. No other differences to control group were found.
A repeated dose toxicity was conducted comparable to OECD guideline 410 (1981) and according to GLP. Due to significant effects on the skin a NOAEL for local effects was determined to be 5,5 mg/kg/day for males and 2.5 mg/kg/day for females. The NOAEL for systemic toxicity was found to be 10 mg/kg/day for both sexes.
A repeated dose toxicity was conducted comparable to OECD guideline 410 (1981) and according to GLP. The aqueous substance was applied at doses of 0, 2.5, 5.5, 10, 30 and 50 mg/kg bw/day. All rats died at the highest concentration, and 8/10 (males and females) at 30 mg/kg/day. No changes in body weight gain or absolute and relative organ weight were noted for the surviving animals. At the 30 mg/kg/day dose level, the two surviving male rats exhibited a significant increase in cholesterol while the two surviving females exhibited a significant increase in total bile acids. A significant decrease in potassium levels at 2.5 mg/kg/day (males) and 30 mg/kg/day (males and females) and significant decreases in urine creatinine values at 10 and 30 mg/kg/day (male and female) were found. Histopathology revealed liver vacuolation (males) with eosinophilic intracytoplasmic material, thymic lymphoid necrosis and pulmonary congestion (males and females) at 30 mg/kg/day TMAH. Inflammation, necrosis and squamous epithelial hyperplasia of the skin was found at 10 mg/kg in males and 5.5 mg/kg in females. Due to the significant effects on the skin a NOAEL for local effects was determined to be 5.5 mg/kg/day for males and 2.5 mg/kg/day for females. The NOAEL for systemic toxicity was established to be 10 mg/kg/day for both sexes.
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SYNTHESIS OF MONOFUNCTIONALIZED CYCLODEXTRIN POLYMERS FOR THE REMOVAL OF ORGANIC POLLUTANTS FROM WATER
EDWARD NDUMISO NXUMALO
Supervisor: Dr B.B. Mamba Co-supervisors: Dr T.J. Malefetse and Dr R.W. Krause
Dissertation submitted in fulfillment of the requirement for the degree of Master of Technology in Chemistry in the Faculty of Science, Department of Chemical Technology, of the University of Johannesburg
EDWARD NDUMISO NXUMALO (Student Number: 820408494)
DECLARATION ________________________________________________________________ I hereby declare that this dissertation, apart from the recognized assistance of my supervisors, is my own work. It is being submitted for the degree of Master of Technology in Chemistry in the University of Johannesburg, Department of Chemical Technology. It has not been submitted before for any degree or examination in any other University, Technikon or College.
on this ____ day of ________________
(Candidate) _____________________________
(Supervisor) _____________________________
(Co-supervisor) _____________________________
(Co-supervisor)
ACKNOWLEDGEMENTS ________________________________________________________________
I hereby wish to express my sincere appreciation to all who contributed in any way whatsoever to the completion of this thesis: •
Dr B.B. Mamba, Dr T.J. Malefetse and Dr R.W. Krause (my supervisors) for their limitless time, infinite knowledge and constant encouragement.
University of Johannesburg (UJ) Research Committee, National Research Foundation (NRF) and the Swaziland Government for their financial support.
Ian Vorster (UJ, Kingsway Campus) and Richard Mampa (University of the Witwatersrand) for running NMR spectra.
My fellow Master's students for their friendship and support.
My family for their support and Bongiwe for her steadfast faith and confidence in me.
God Almighty for helping me to realize that I have more strength than I thought. Now I know that there is nothing I cannot do.
DEDICATION ________________________________________________________________
This work is dedicated to my younger sister (Ngeti), my mom (Grace) and my "dearest" Bongiwe.
"...because there is nothing impossible if you find your strength from within..."
TABLE OF CONTENTS _______________________________________________________________ SECTION
Glossary of terms and abbreviations
1.2 Project justification
1.3 Aims and objectives
1.4 Outline of dissertation
2.2 Current water purification technologies
2.3 Cyclodextrin technology
2.3.1 History of CDs
2.3.2 What are CDs?
2.3.3 Chemical properties of CDs
2.4 Cyclodextrin derivatives
2.4.1 Monomodification of cyclodextrins
2.4.1.1 Primary face modification
2.4.1.2 Secondary face modification
2.4.2 Cyclodextrin polymers
2.4.2.1 Thermal analysis of CD polymers
2.5 Formation of inclusion complexes
2.6 Analysis of priority organic pollutants
EXPERIMENTAL METHODOLOGY
3.2 Experimental methodology
3.2.1 General procedure
3.2.1.1 Thin layer chromatography (TLC)
3.2.1.2 Nuclear Magnetic Resonance (NMR) spectroscopy
3.2.1.3 UV, IR and GC/MS spectrophotometer
3.2.1.4 Reactions and reagents
3.2.2 Numbering system adopted for cyclodextrins
3.2.3 Synthetic procedures
3.2.3.1 Synthesis of monofunctionalized CDs
3.2.3.2 Synthesis of monosubstituted CD polymers
3.3 Thermal analysis of CD polymers
3.4 Testing absorption abilities of the monofunctionalized CD polymers
3.4.1 UV absorbance experiments
3.4.2 GC/MS experiments
3.4.2.1 Introduction
3.4.2.2 Operating principle for the GC/MS
3.4.2.3 Procedure for the preconcentration of water samples 59 3.4.2.4 Preparation of PCP samples
3.4.2.5 EPA Method 8270 for semivolatile organic compounds
4.2 Synthesis and characterization of monofunctionalized β-CD derivatives
4.2.1 Synthesis and characterization of the CD monotosylate
4.2.2 Synthesis and characterization of 6-monosustituted β-CD derivatives
4.2.3 Synthesis and characterization of 2-monosubstituted β-CD derivatives
4.3 Synthesis and characterization of monofunctionalized CD polymers
4.3.1 Synthesis and characterization of the diisocyanate CD polymers
4.3.2 Synthesis and characterization of the ADP and EPC CD polymers
4.4 Thermal analysis of the CD polymers
4.4.1 Thermal gravimetric analysis
4.4.2 Differential scanning calorimetry analysis
4.4.3 Conclusion
4.5 Absorption studies of the monofunctionalized CD polymers
4.5.2 UV-Visible spectroscopy results
4.5.2.1 Absorption capabilities of the diisocyanate polymers 98 4.5.2.2 Absorption capabilities of ADP and EPC polymers
4.5.3 GC/MS results
4.5.3.2 Absorption studies of the diisocyanate polymers
4.5.3.3 Absorption studies of the ADP and EPC polymers
4.5.3.4 Conclusion
4.6 References CHAPTER 5
109 CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions
5.2 Recommendations
APPENDICES Appendix A: Selected IR and NMR spectra
Appendix B: Selected PGA and DSC curves
Appendix C: Selected GC/MS Chromatograms
Appendix D: List of pollutants and their effects
LIST OF TABLES ________________________________________________________________ TABLE Table 2.1:
DECSRIPTION
Physical properties and molecular dimensions of the most common types of cyclodextrins
Table 2.2:
What thermal analysis can reveal about polymeric materials 33
A summary of the loading procedures
A summary of the eluting procedures
Procedure for absorption by SPE Method
Operating conditions for EPA Method 8270 for determination of semi volatile organic compounds
C NMR chemical shifts, δ (ppm) of C-H carbon in
mono-6-tosyl β-CD in DMSO-d6 Table 4.2:
Table revealing the yields and linkers used for the different monofunctionalized diisocyanate CD polymers
1st, 2nd, 3rd, and 4th weight loss steps in the TGA curves of some monofunctionalized polymers
Table 4.7a:
Results obtained after treating 10mg/L PNP water samples with monofunctionalized TDI-linked β-CD polymers
Results obtained after treating 10 mg/L PNP water samples with monofunctionalized HDI-linked β-CD polymers
Table 4.7b:
Table revealing the yields of the monofunctionalized ADP and EPC CD polymers
Yields and physical appearances of the β-CD derivatives Synthesized
mono-6-diaminoethyl CD in DMSO-d6 Table 4.3:
Results obtained after treating 10 mg/L PNP water samples with monofunctionalized ADP-linked β-CD polymers viii
Results obtained after treating 100 µg/L PCP water samples with monofunctionalized HDI and TDI-linked β-CD polymers 103
Table 4.9b
Results obtained after treating 100µg/L PCP water samples with monofunctionalized TDI-linked β-CD polymers
Table 4.10:
Results obtained after treating 100 µg/L PCP water samples with monofunctionalized ADP and EPC-linked β-CD polymer 107
LIST OF FIGURES ________________________________________________________________ FIGURE
Figure 2.1:
The structures of the three common types of cyclodextrins
Schematic representation of the cone shape of the
cyclodextrin
The structures used to represent CDs in this dissertation
The three different hydroxyl groups of the cyclodextrins
Examples of structures of commonly known POPs
The structure of the β-cyclodextrin illustrating the numbering system used in this dissertation
The structure of a monofunctionalized HDI polymer
The structure of a monofunctionalized TDI polymer
Diagram showing the modified SPE used in this project
Structure illustrating details of the hydroxyl groups (OH-2 and OH-3) which participate in the formation of intramolecular bonds
C NMR (DMSO-d6) spectrum of unsubstituted β-CD
C NMR (DMSO-d6) spectrum of p-toluene sulfonic
H NMR spectrum of unsubstituted CD in DMSO-d6
anhydride
The structure of mono-6-tosyl β-cyclodextrin
The structure of mono-6-acetyl β-cyclodextrin
The structures of the linkers used to synthesize polymers in this study
The IR spectra illustrating the disappearance of the isocyanate peak during the formation of the mono-2-benzoylated CD
IR spectrum of 6-CDAc/TDI
Figure 4.10: IR spectrum of 2-CDOMe/HDI
Figure 4.11: IR spectrum of (a) 6-CDAc/ADP and (b) 6-CDOAm/ADP
Figure 4.12: IR spectrum of 6-CDOAm/EPC
Figure 4.13a: TGA curve of a standard polymer (CD/HDI polymer)
Figure 4.13b: TGA curve of a monofunctionalized polymer (2-CDOBz/HDI polymer)
Figure 4.13c: TGA curves of 2-CDOBz/ADP and 2-CDOBz/EPC
Figure 4.14a: A DSC curve of a standard polymer (CD/HDI)
Figure 4.14b: A DSC curve of a monofunctionalized polymer (2-CDOBz/HDI polymer)
Figure 4.15: A DSC curve of 6-CDOAm/HDI)
Figure 4.16: A DSC curve of 2-CDOMe/TDI)
Figure 4.17: GC/MS chromatographs showing the treatment of a 100 µg/L sample with a 2-CDOBz/TDI polymer
Figure 4.18: GC/MS chromatographs showing the treatment of a 100 µg/L sample with a 2-CDOBz/HDI polymer
GLOSSARY OF TERMS ________________________________________________________________ α-CD
Alpha Cyclodextrin
β-CD
Beta Cyclodextrin
γ-CD
Gamma Cyclodextrin
µg/L
micrograms per litre
Angstrom Unit
Anhydrous glucopyranosyl units
Bimolecular Nucleophilic Substitution
Residual Concentration
Cyclodextrins
6-CDOAc
Mono-6-acetyl β-cyclodextrin
2-CDOAllyl
Mono-2-allyl β-cyclodextrin
6-CDOAm
Mono-6-daminoethyl β-cyclodextrin
2-CDOBz
Mono-2-benzoyl β-cyclodextrin
2-CDOMe
Mono-2-methyl β-cyclodextrin
6-CDOTs
Mono-6-tosyl β-cyclodextrin
Initial Concentration
Doublet of doublet
N,N-Dimethyl formadide
DMSO-d6
Deuterated DMSO
Electron Ionization
Endothermic Peak
EtOAc
GC/MS
Gas Chromatography / Mass Spectroscopy
Glass Transition Temperature
Hexamethylene diisocyanate
Humic Substance
LLE
m/z
Mass to charge ratio
Mega Hertz
M.pt
milligrams per litre
Multiplet
ng/L
nanograms per litre
nanometer
Value taken to represent the acidity or alkalinity of an aqueous solution
Para-nitrophenol
Polyaromatic hydrocarbons
Persistent Organic Pollutant
parts per billion
parts per trillion
TBDMSCl
Tert-butyldimethyl silyl chloride
TBAF
Tetrabutyl ammonium fluoride
Toluene 2,4-diisocyanate
Ts2O
Toluene sulfonic anhydride
TG/MS
Thermogravimetric-Mass Spectrometry
THMs
Trihalomethanes
Total ion count
Water Research Commission
ABSTRACT ________________________________________________________________
Water is an important resource. It is used for domestic, industrial, agricultural and recreational purposes. The quality of water is, however, significantly deteriorating due to the accumulation of organic species in aqueous system. Domestic, industrial and commercial activities comprise the biggest source of organic pollutants in municipal water. The increase of water pollution by these organics has led to the development of several water purification measures. Among others, water treatment technologies that are in place consist of ion exchange, activated carbon adsorption, reverse osmosis, molecular sieves and zeolites. However, none of these techniques have been reported to remove organic pollutants to parts-per-billion (ppb) or microgram-per-litre (µg/L) levels. Recently, it has been reported that cyclodextrin nanoporous polymers are capable of absorbing these pollutants from water to such desirable levels.
Cyclodextrins (CDs), basically starch derivatives, are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4-glycosidic linkages. They behave as molecular hosts capable of interacting with a range of guest molecules in a noncovalent manner within their cylindrical hydrophobic cavities. These interactions are a basis for the inclusion of various organic species. However, the high solubility of cyclodextrins in aqueous medium limits their application in the removal of organic pollutants from water. To make them insoluble, they are converted into highly cross-linked polymers. This is achieved by polymerizing the cyclodextrins with suitable difunctional linkers.
In this project, a wide variety of monofunctionalized CDs have been effectively prepared using efficient modification strategies and successfully characterized by Infra-red (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. From these monofunctionalized CDs and corresponding linkers, insoluble nanoporous polymers with different physical properties were synthesized (Scheme 1).
RX Base
Monofunctionalized CD
N H
O Monofunctionalized CD polymer
Scheme 1: A general synthetic pathway for a monofunctionalized CD polymer.
The insoluble polymers obtained have demonstrated great capabilities in removing phenolic compounds (p-Nitrophenol and pentachlorophenol) at very low levels of concentrations from water. The absorption efficiencies of these polymers were generally similar to those of the unfunctionalized CD polymers (standard polymers). The degree of absorption was quantified and measured using UV-Visible spectroscopy and GC-MS analysis.
The thermal stabilities of the polymers were also investigated in this study using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It has been established that these novel polymers are stable over a wide range of temperatures (100 oC – 400 oC).
CHAPTER 1 INTRODUCTION _______________________________________________________________
The removal of organic contaminants from water is a serious challenge for chemists. As a result of growing economic and industrial development, there is hardly an area that has not been affected by the problem of water contamination. As a response to this problem, several technologies and materials have been employed to remove organics from water. These include the use of activated carbon adsorption,1
zeolites,2 reverse osmosis,3 and molecular sieves.4
However, none of these techniques have been reported to remove organic contaminants dissolved in aqueous media at parts-per-billion (ppb) levels. Examples of organic compounds found in water supplies that are difficult to remove
chlorinated
(e.g.
tetrachloroethylene) and aromatic compounds such as benzene, toluene and phenol and their derivatives.5 Owing to the toxicity of these organic contaminants, there is a growing need for the development of efficient methods for their removal. Recent work has explored the use of a new class of nanoporous
contaminants from water to the desired levels.6
Cyclodextrins, a class of cyclic compounds, tend to form inclusion complexes with various organic compounds. The most common CDs (loosely named parent
CDs) are composed of 6, 7 and 8 glucose units and are known as α-, β- and γCDs, respectively. Their well-defined cylindrical inner cavities, which are hydrophobic, allow for absorption of organic pollutants from an aqueous medium. However, the solubility of the parent CDs in water restricts their usage in water treatment. To make them water-insoluble they are converted into highly crosslinked polymers.
Recent work involving the synthesis of insoluble cyclodextrin polymers using bifunctional cross-linkers has been reported.6 Li and Ma7 have utilized linkers such
(EPC),
toluene-2,4-diisocyanate
(TDI)
hexamethylene diisocyanate (HDI) in the formation of these nanoporous cyclodextrin polymers. To the best of our knowledge, no study has been conducted in which monofunctionalized cyclodextrin polymers are employed for the removal of organic pollutants from aqueous media. As a consequence, it is not known how various functional groups attached to the polymer backbone would affect the performance of the polymer.
This project, therefore, seeks to synthesize and characterize monosubstituted CD polymers or "nanosponges" as they are often referred to. These new desired polymers possess an enhanced ability to quench organic contaminants from water to acceptable levels. The synthetic process entailed monofunctionalization of the primary or secondary hydroxyl groups of the parent CD compounds followed by crosslinking with a suitable bifunctional linker to give the desired nanoporous polymers. These polymers were then tested for the ability to absorb organic compounds from water.
The primary objectives of this study were to:
Synthesize and characterize monosubstituted cyclodextrins from the parent cyclodextrins. The characterization was performed by IR and NMR spectroscopy as well as other analytical techniques available in our laboratories.
Synthesize and characterize monosubstituted cyclodextrin polymers using the monosubstituted cyclodextrins synthesized in (i) and selected suitable bifunctional cross-linkers such as diisocyanates and diacid chlorides. The characterization of the polymer was carried out by IR spectroscopy. An example of a general scheme for such reactions is given in Scheme 1.1.
R X1 OH
OH C y c lo d e x trin
M o n o f u n c t io n a liz e d C D
c r o s s lin k in g w it h b ifu n c tio n a l lin k e r X2 L IN K E R X2
L IN K E R
M o n o f u n c t io n a liz e d C D P o ly m e r X 1 , X 2 = C l, B r , I, e t c
Scheme 1.1: Synthetic pathway for monofunctionalized CD polymers.
Study the thermal stability of the monofunctionalized CD polymers using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).
Test the ability of the polymers to absorb organic contaminants from water
experiments.
experiments involve deliberately placing solid nanoporous polymers into an aqueous solution containing known concentrations of the organic contaminants. GC-MS and UV-Visible spectroscopy were used in quantifying the degree of absorption.
Perform comparative studies of the absorption capabilities for the monofunctionalized CD polymers and the unfunctionalized CD polymers.
During the synthesis of these compounds optimization of the synthetic pathway was carried out by varying reaction conditions such as temperature, solvents and reaction times. From a range of linkers at our disposal, it is evident that for one monofunctionalized cyclodextrin moiety, there is an almost unlimited number of polymers that could be prepared. While insoluble CD polymers are the target compounds, soluble polymers, which have not been prepared before, can also be obtained and characterized.
1.4 Outline of the dissertation
Chapter 1 serves to provide a concise summary of the background, justification as well as the aims and objectives of the project. A brief introduction of the outline of this dissertation is also discussed in this chapter.
In Chapter 2, the literature covering the structure and physical properties of cyclodextrins, modified cyclodextrins and cyclodextrin polymers is reviewed. Available methods employed in the monofunctionalization of CDs have been discussed here in detail. This chapter also gives a brief overview of existing water purification technologies and materials such as activated carbon, molecular sieves, zeolites and dendrimers. In addition, methods that have been utilized to study the thermal properties of CDs have been highlighted in this chapter.
The objective of Chapter 3 is to summarize the experimental strategies employed as well as the results obtained for the synthesis of monofunctionalized CDs and the corresponding polymers. The analytical techniques and procedures used in experiments for testing the absorption abilities of the polymers are also mentioned under this section.
Chapter 4 provides an indepth analysis of the results obtained in the previous chapter. Specifically, it features characterization of both the monofunctionalized CDs and the polymers. An investigation of the effect of the substituents on the absorption properties of the resultant polymers is also discussed.
In Chapter 5 conclusions and recommendations based on the results obtained from this study are made.
The Appendices outline selected IR and NMR spectra, GC/MS chromatographs, DSC and TGA curves as well as types of pollutants, their sources and effects.
1. Bacaoui A., Dahbi A., Yaacoubi A., Bennouna C., Maldonada-Hodar F.J., Rivera-Utrilla J., Carrasco-Marin F., Moreno-Castilla C., Environ. Scie. Technol. 36 2002 3844. 2. Cama J., Ayora C., Querol X., Ganor J., Environ. Scie. Technol. 39 2005 4871. 3. Wu S. H., Pendleton P., J. Colloid and Inter. Scie. 243 2001 306. 4. Halasz I., Kim S., Marcus B., Molecular Phys. 100 2002 3123. 5. Gallard H., von Gunten U., Water Res. 36 2002 65. 6. Li D. Q., Ma M., Filtr. and Separ. 36 1999 26. 7. Li D. Q., Ma M., J. Am. Chem. Soc. 11 1999 872.
CHAPTER 2 LITERATURE REVIEW _______________________________________________________________
Water is a vital resource that is essential for the existence of life on earth. It is used in a wide variety of manufacturing and industrial processes. To ensure that it is acceptable for human consumption its quality should conform to certain health standards.1 Contamination of water by organic compounds is, however, inevitable because synthetic materials are used in every aspect of our daily lives. In urban areas, municipal and industrial effluents pollute water sources. In farming areas agricultural activities can lead to deterioration in water quality.2 Organic contaminants are a public health concern as they can be harmful when present above acceptable concentrations in drinking water. The serious challenge faced by local governments and industries is the removal of these contaminants from aqueous systems. This has therefore led to the development of several water purification technologies. These are discussed briefly in the following section.
Technologies for the removal of organic contaminants that are in place are activated carbon, zeolites, molecular sieves, reverse osmosis, and dendrimers. While activated carbon adsorption is currently the most popular technology for the removal of organics in water,3 it however fails to remove organic contaminants at parts-per-billion (ppb) levels.
Zeolites have also been described as another viable alternative in mitigating this problem.4 These are basically crystalline solids with well-defined structures. Because of their unique porous properties, they have been used in ionexchange. They, however, show little affinity for organics and thus cannot be used extensively in water purification.
A third technique uses molecular sieves, which contain a network of uniform pores and empty cavities. These compounds are metal alumino-silicates having a three dimensional network of silica and alumina tetrahedra.5 They are non-toxic and are insoluble in water as well as most organic solvents; they are often used as selective absorbents for both organic and inorganic materials. Molecular sieves, however, tend to easily absorb water thus losing their effectiveness in the process. As a result, they fail to remove organic compounds at very low levels of contamination.
Reverse osmosis is considered as another efficient method of removing contaminants from water and has been successfully used in many applications such as desalination of seawater.6 The disadvantage of this technology is that it requires high pressure in order to overcome the resistance produced by the dense membrane used, which consumes a lot of energy. It is also difficult to recover all of the water entering the system and it does not remove the smallest organic molecules. Therefore, the high cost associated with this technology makes it an ineffective and wasteful large scale decontamination technique.
Long-chain alkylated dendrimetic derivatives have recently been reported as another viable technology for the removal of organic contaminants.7 These are effective nanosponge materials that are particularly effective for the inclusion of toxic polycyclic aromatic compounds dissolved in water; they are capable of -9-
removing these contaminants from water to parts-per-billion levels. The high cost benefit of this technology has however prohibited further investigation.
Recently, it has been reported that cyclodextrins polymers are capable of removing a wide range of organic contaminants from aqueous systems present at ppb levels.7
2.3.1 History of cyclodextrins
Cyclodextrins were first discovered by Villiers8 in 1891 as by-products of the enzymatic degradation of Bacillus macerans amylase on starch. Schardinger9 then developed a detailed method for the synthesis and separation of cyclodextrins. This method takes advantage of the solubility properties of the cyclodextrin oligomers, using organic solvents to induce the selective precipitation. CDs are capable of forming inclusion complexes of the host-guest type with organic compounds of certain sizes and can act as catalysts that mimic enzymes in their regio- and stereo-specificity. Recent industrial applications of CDs are numerous. They include everything from food chemistry, biotechnology, analytical chemistry, pharmaceuticals, cosmetics, pesticides, and polymers.
2.3.2 What are cyclodextrins?
Cyclodextrins are biosynthetic cyclic oligomers composed of anhydrous glucopyranosyl units (AGU). The glucose units are linked together by α-1,4linkages.10 Other common names used occasionally in the naming of these compounds are Schardinger dextrins, cycloglucans and cycloamyloses.
The three most common cyclic oligosaccharides are α-, β- and γ-CD (shown in Figure 2.1), consisting of six, seven and eight glucose units, respectively.11 CDs consisting of more glucose units also exist, but they are currently too expensive to be utilized in the development of practical applications.12
HO O
O OH
O HO
O O HO
β-cyclodextrin
HO HO
α-cyclodextrin
OH HO
HO OH
γ-cyclodextrin
Figure 2.1: The structures of the three common types of CDs.
As shown in Figure 2.2, these enzymatic starch products have characteristic toroidal shapes that form well-defined cylindrical cone-shaped cavities. They possess hydrophilic exteriors and hydrophobic interiors. The hydrophilic surface
allows CDs to dissolve in water, whilst the hydrophobic cavity can host several different compounds.
Figure 2.2: Schematic representation of the cone-shaped structure of the cyclodextrin.10
Several structures have been used to represent cyclodextrins. However, in this dissertation, the following structures will be used regularly to represent cyclodextrins. These are shown in Figure 2.3.
C4 HO
H C6
C5 C3 H H
O H
H O n
n = 6,7,8
OH (b)
Figure 2.3: The structures used to represent the CD molecule in this dissertation.
The cyclodextrin rings are about 8 Å deep and 5-10 Å in diameter, depending on the number of glucose units. Other important physical properties and molecular dimensions are shown in Table 2.1.
Table 2.1: Physical properties and molecular dimensions of the most common types of cyclodextrins. Property
α-CD
Number of glucose units
Molecular weight (g.mol-1)
Water solubility (g.100ml-1) 25 oC
Specific rotation [α]D25
150.5 ± 0.5
Internal diameter (Å)
External diameter (Å)
Height cone (Å)
Cavity volume (Å3)
CDs possess numerous functional groups; they can, therefore, undergo a wide variety of chemical reactions.12 These may involve cleavage of the O-H, C-O, C-
H or C-C bonds. The most frequently studied reaction is the electrophilic attack of the hydroxyl groups. The α-, β-, and γ-CD contains 18, 21 and 24 OHs, respectively. Thus, each CD moiety has several sites of modification.13 The reactivity of the hydroxyl groups can be exploited by forming monosubstituted derivatives. However, the significance of this modification is only realized once the solubility of the resulting polymers has been established.
There are basically two primary factors that need to be considered in the modification of the hydroxyl groups of the CDs: 1. the nucleophilicity of the hydroxyl groups 2. the ability of CDs to form complexes with the reagents used.
Most modifications of CDs take place at the hydroxyl groups. As shown in Figure 2.4, there are three types of hydroxyl groups (OH's) present in CDs; one primary (C-6) and two secondary (C-2 and C-3).14,15
OH 4
2 OH 3
Primary alcohol
OH O
Secondary alcohol
Figure 2.4: The three different types of hydroxyl groups of a CD.
The C-6 hydroxyl groups are the most basic and thus most nucleophilic, the C-2 hydroxyls are most acidic and the C-3 hydroxyls are the most inaccessible because they are sterrically hindered. Therefore, under normal circumstances,
an electrophilic reagent attacks at the most reactive C-6 OHs. The C-2 OH's are the most susceptible to deprotonation,16 and the oxyanion formed is considered to be more nucleophilic than the non-deprotonated OH's at the C-6.
Chemically modified CDs are synthesized so as to vary their solubility behavior, to modify their complexation properties (i.e. stability constant, guest selectivity) and to introduce functional groups that can achieve specific functions (e.g. catalytic activity).
There are generally two common ways in which the CD hydroxyls groups can be functionalized: i. monofunctionalization - functionalizing of only one hydroxyl group. ii. per-functionalization – functionalizing of an entire set of hydroxyl groups. Although di- and tri-functionalizations exist,17 they have not been well investigated and are difficult to perform. Monofunctionalization of the CDs have, however, been well studied in the functionalization of these starch derivatives.18 These monofunctionalizations can be achieved by a reaction of the hydroxyl groups with an electrophile. The large number of hydroxyl groups at the three different positions of CDs makes modification at a single desired place complicated.19 Although selective monofunctionalization at a desired position is a challenging task, the differences in the chemical properties and reactivities among these sites can be exploited to yield a specific product.
Monosubstitution of a CD is achieved by using less than one equivalent of the reagent. The presence of a large excess of the electrophilic reagent must be avoided as it often lead to di-, tri or per-functionalization.20
Because the primary hydroxyl C-6 groups of the macrocycle are easily accessible, they tend to react preferentially with bulky reagents. Under anhydrous conditions the C-2 OH's can be selectively deprotonated and allowed to react with electrophilic reagents. The C-3 OHs can react only after (C-2) and (C-6) have been blocked.
Required substituents may be introduced to the CD directly through alkylation, acylation and sulfonation. Alternatively, sulfonates, halides and related species may be prepared as intermediates for the subsequent introduction of other substituents through nucleophilic displacement. In turn, an amino group incorporated in a similar manner provides a nucleophilic site for further elaboration. Oxidation of the hydroxyl groups of the CDs produces aldehydes and ketones while reactions with acid chlorides (benzoyl chloride, ethanoyl chloride) and acid anhydride e.g. phthalic acid anhydride, yield esters.21 Reactions with sulphonic acid chlorides and alkylhalides yield sulphonic esters and ethers, respectively.22
2.4.1.1 Primary face monomodification
(a) Monosubstitution at the 6-position of the CDs
The most common method for functionalizing at the 6-position of the CDs is nucleophilic attack of a reagent containing the appropriate group on mono-6-tosyl CD (itself a monosubstituted CD). Monosulfates are prepared by reacting one equivalent of p-toluenesulfonyl chloride with CD in pyridine or DMF in the presence of a base. Monotosylates have been extensively investigated.23,24 An excellent method for the synthesis of monotosyl CD is by the reaction of a CD moiety with p-toluene sulfonic anhydride (Ts2O) in aqueous alkaline medium for a short period of time to obtain the mono-6-tosylate (Scheme 2.1) in a fairly good yields.25
Ts2O NaOH/H2O
Mono-6-tosyl CD
Scheme 2.1: Conversion of the cyclodextrin to the mono-6-tosyl CD.
Tosyl CDs are important precursors to a variety of modified CDs because nucleophiles can attack the electrophilic carbon atom at the 6-position to produce other functionalized derivatives.26 Several nucleophiles can displace the tosyl group on the CD to yield the corresponding modified CD. These include
nucleophiles such as iodide, azide, thioacetate, hydroxylamine, aryl or polyalkylamine. These can displace the tosyl group to afford monoiodo-,27 monoazido-,28,29 monothio-,30,31 and monoalkylamino cyclodextrins,32,33 (Scheme 2.2).
Mono-6-iodo CD
NaN3
Mono-6-azide CD
H2N
R = Alkyl group
Mono-6-formyl CD Mono-6-toluidinyl CD Mono-alkylated CD Scheme 2.2: Conversion of tosyl CD to the corresponding functionalized
This strategy has also been used in the synthesis of artificial enzymes where only one functional group, which acted as a catalyst, was attached to the 6position of CDs.34 This was achieved by reacting a nucleophile containing the catalytic species with the 6-tosylated CD to give the desired artificial enzyme.35 A variety of other derivatives have been prepared by displacing the tosyl group from the 6-position of CD. Bulky groups such as 4-N-(tert-butoxycarbonyl)-2ethylimidazonyl have been linked to the CD and characterized by X-ray diffraction (XRD).36 Monotoluidinyl CDs (Scheme 2.2) that can recognize the size, shape and chirality of amino acids with good enantioselectivity have been synthesized in a similar manner.37 Essentially the same strategy has been utilized in the synthesis of a mono-hydroxylamine derivative of CD.38
Monothio derivatives are synthesized from monotosylates or mono-iodo CDs and the respective alkyl thiolate ion. A variety of mercapto CD derivatives that have been obtained from monotosylated CDs have been used to study immobilized films on gold surfaces.39 The direct synthesis of monothio CDs with aromatic thiol and unprotected CD in DMF or pyridine is performed through a thio-Mitsinobu reaction. This reaction gives a mixture of mono-, di-, and trisubstituted products which are further purified by chromatography.40
Monoamino derivatives of CD have also been reported.41 These are conveniently obtained from monoazides of CDs by reduction with triphenylphosphine in the presence of ammonia. Monoazides of CDs are indirectly obtained by heating the monotosylate with sodium or lithium azide salt containing triphenylphosphine in DMF.42 Monoamines show greater solubility in organic solvents and react with isocyanates without the need to protect the primary hydroxyl groups to produce isocyanato CDs.
Like the monotosylates, monoaldehydic CD derivatives are also important because they provide a route for further modifications. The monoaldehyde has been prepared by oxidizing mono-6-tosyl CD using DMSO and collidine as a hindered base (Scheme 2.2).43,44
They can also be synthesized by reacting the CDs with Dess-Martin periodinane in 85-100% yields.45,46 Oxidation of the monoaldehyde leads to its carboxylic acid derivative. Hydroxylamine reacts with the monoaldehyde to produce a monohydrazone derivative.43 Alkyl ethers of CDs cannot be synthesized from tosylates because nucleophiles in this case (alkoxide ions) act as strong bases which abstract protons from the C-3 OHs and produce the 3,6-anhydro compounds by ring conversion.47 This kind of ring inversion is shown in Scheme 2.3.
OTs O-
OH n
Cyclodextrin monotosylate (n = 6, 7, 8) -OTs
3,6-anhydro Cyclodextrin
Scheme 2.3: Conversion of the monotosylate to a 3,6-anhydro CD during ring inversion.
β-CD alkyl ethers are obtained by a longer method in which the primary side is first protected by tert-butyldimethyl silyl chloride (TBDMSCl). This is followed by per-methylation of the secondary face, desilylation of the primary side and then monotosylation of the primary side. The reaction of the alkoxide ion with this protected tosylate gives the desired alkyl ether on the primary side without the formation of the 3,6-anhydro derivative.47 The main problem with this approach is that the methyl groups in the secondary side cannot be easily removed. This limitation can be overcome by using acetyl groups to protect the secondary side that can be subsequently hydrolyzed.
The direct approach for alkylation has been demonstrated.48 This reaction involves the treatment of the CDs with alkyl halides in an alkaline solution to afford a mixture of products which are, in turn, separated by chromatographic methods.49,50 An example of a random reaction is hydroxypropylation which results in a mixture of primary and secondary side derivatives. Such a substitution reaction can be controlled by the concentration of base used during the reaction.51
(dicyanoanthracene) derivative.52 The pyrolysis of solid complexes of CDs aromatic diazo compounds is another good example of a direct approach for monoalkylation.53 This reaction proceeds via the insertion of carbine into hydroxyl groups. The mixture of 2-, 3-, and 6-O-isomers produced are in turn separated by HPLC to give the desired monoalkyl CD derivative.
2.4.1.2 Secondary face monomodification
(a) Monosubstitution at the 2-position of the cyclodextrin
Although very few 2-monosybstituted CDs derivatives are known, mono-2-tosyl β-CD has been synthesized using several strategies. m-nitrophenyl tosylate reacts with CD in a DMF/aqueous buffer at pH 10 in a low yield. This reaction proceeds via complex formation to transfer the tosyl group to the 2-position.54 The tosyl group gets transferred preferentially to the 2-position due to the orientation of the reagent with the host molecule. This procedure is referred to as the group transfer strategy. Several workers have prepared mono-2-tosylate derivatives of CDs as a mixture of other isomers by using an aqueous alkaline medium or DMF and p-toluene sulfonyl chloride.55 These have been well characterized after chromatographic purification of the mixture.56-58 Dibutyltin oxide has been used to facilitate this reaction in DMF.59
The mono-2-mesylate derivative of the β-CD has also been reported60 (Scheme 2.4). Other examples of mono-2-sulfonates such as nitrobenzenesulfonyl or naphthalenesulfonyl groups, also obtained as mixtures and later purified, are mentioned in the literature.61,62
OH CH3SO2Cl
SO3CH3
Mono-2-mesyl CD
Scheme 2.4: Synthesis of mono-2-mesyl cyclodextrin.
As noted earlier, the hydroxyl groups at the 2-position are more acidic than those at the 6-position. This feature has been exploited by using sodium hydride (NaH) or lithium hydride (LiH) as strong bases under anhydrous conditions for selective tosylation at the 2-position, as shown in Scheme 2.5.
NaH 3
O-Na+
Cyclodextrin oxyanion
Scheme 2.5: The deprotonation reaction of the C-2 secondary hydroxyl groups.
Yields in all these reactions are reduced by the elimination of the sulfonate group due to its good leaving behavior.54 The elimination of the tosyl group at the 2position by the hydroxyl groups affords the manno-2,3-epoxy CD (Scheme 2.6). Symmetrical alkyl ethers with substitutions at all three positions have been
synthesized. Mono-(isoalloxazinomethyl) CD64 is another example of a mono-2ether which is obtained by exploiting the acidity of the 3-hydroxyl group by reacting with a strong base and subsequent conversion of the product to a flavin moiety after several steps.65,66
Mono-2-methyl, -ethyl and -allyl derivatives are prepared directly from CDs and the respective dialkyl sulfates in aqueous solution, giving very low yields after purification.17 Mono-2-propyl derivatives are obtained by hydrogenation of the mono-2-allyl CDs. Monoalkyl ethers with terminal aromatic esters appended through amide linkage show intramolecular inclusion complex formation.63
Mono-2,3-epoxy CDs are synthesized from the classic monotosylate in a basic medium.67 As presented in Scheme 2.6, two types of epoxides are produced during the reaction depending on the position of the sulfonate group on the cyclodextrin ring.68
ARSO2Cl
NsSO2Cl
NaH OH
O3SAR
Manno-2,3-epoxy CD
SO2Cl
NsSO2Cl =
ARSO2Cl =
Benzene sulfonyl chloride
Naphthalene sulfonyl chloride
Scheme 2.6: Synthesis of the cyclodextrin epoxides from the cyclodextrin monotosylate.
The per-6-silylated manno-mono-2,3-epoxy derivative is synthesized from the per-6-sily-mono-2-tosyl derivatives. Mono-2-amino CDs have been synthesized from per-acetylated CDs of all the three types of these starch derivatives (α-, βand γ-CDs) by the cleavage of the CD ring in an acidic medium.69 This is subsequently followed by coupling with the glucosamine derivatives which gives the final products after several steps of cyclization and deprotonation.
Another method for the synthesis of this compound (mono-2-amino CD) involves the use of per-benzoylated β-CD. This reaction also involves a number of steps including de-benzoylation reaction at one of the C-2 hydroxyls, followed by oxidation and oxime formation, and finally reduction of the oxime. Scheme 2.7 summarizes the strategies that have been used in modification of the hydroxyls at the 2-position.
(a) R = Tosyl R1=TBDS
(b) OR 2
(f) (d)
(e) 6
OR1
Scheme 2.7: Strategies for modification at the 2-position of CDs; (a) complex formation, (b) tosylate formation, (c) electrophilic reagent (in a strong base), (d) protection of the primary site with TBDS, (e) electrophilic reagent and (f) deprotection of TBDS.47 The OHs are not shown for the sake of clarity.
(b) Monosubstitution at the 3-position of the CDs
Monosubstitution at the 3-position is complicated by the fact that the hydroxyl groups at this position are most inaccessible and thus less reactive compared to the highly accessible ones (C-2 and C-6 hydroxyl groups). Most modifications of the C-3 OHs proceeds via the synthesis of manno-mono-2,3-epoxy CD (Scheme 2.6). For example, p-toluene sulfonyl chloride has been reacted with the epoxy CD to give the mono-3-tosylates, at very low yields.55,70 However, higher yields have been obtained when 2-naphthalene sulfonyl and 3-nitrobenzene sulfonyl chloride reacted with the CD.71,72
Thio derivatives are produced by reacting the mono-3-sulfonates with alkali thiolates in DMF.73 This is an SN2 type of reaction. Under basic conditions these intermediary sufonates can be converted to allo-mono-2,3-epoxy CDs.74
Generally, epoxy CDs react with certain nucleophiles to give a substitution at the 3-position. Mono-3-amino CDs are synthesized by this method i.e. by treatment of manno-2,3-epoxy CDs with ammonia solution at room temperature.75,76 Subsequently, hydroxylamine reacts with this epoxide to give 3-hydroxylamino CD.77 Various nucleophiles have been utilized in the opening of the epoxy ring of per-6-silyl-mono-2,3-epoxy CD to produce exclusively 3-substituted derivatives.78 These include among other nucleophiles ethylenediamine, lithium azide or anhydrous ammonia.
Homo- and heterodimers, which have been protected, are formed by coupling amino-6-α- and β-CDs with the phenyl ester of a dicarboxylic acid. The products obtained are then desilylated with tetrabutylammonium fluoride (TBAF) by
refluxing with THF to give the matching CD derivatives.79 To obtain mono-3-aryl CDs, the primary hydroxyl groups are first protected with TBDMS and then reacted with a specific alkyl halide (4-methylamino-3-nitrobenzyl chloride) in lutidine at high temperatures. This is shown in Scheme 2.8. The protected CD is believed to complex with this reagent to direct its reactive site towards the OH at the 3-position to give the product.80
OTBDMS
OH TBDMSCl
NHCH3
2,6-Lutidine
OH OTBDMS TBAF O O
NHCH3 NO2
Mono-3-alkyl amino CD
Scheme 2.8: Synthetic scheme for mono-3-aryl amino cyclodextrin.
Cyclodextrins fixed into polymeric structures behave differently from their monomeric derivatives. Depending on the reaction conditions, polymers can be subsequently prepared from difunctional cross-linking monomer units such as epichlorohydrin, diisocyanates, dicarboxylic acid dichlorides, to mention a few. Such reactions should afford either soluble or insoluble polymers. The most thoroughly
studied
cross-linking
epichlorohydrin.81 Among the cross-linked polymer derivatives are those which are smaller in size and soluble in water and larger ones that are insoluble in any solvent but swell in water.
Recently, a series of CDs have been found to initiate the polymerization of cyclic esters selectively without any co-catalyst and co-solvents. The products were polymers with the CD moiety at the end of the chain.82 Moderately high molecular weight CD polymers have also been reported.83 These are known to significantly increase the solubility of drugs.84 Hinze85 has reviewed cyclodextrin polymer application in chromatographic separations and purification methods of cyclodextrins and its derivatives including their polymers. A functionalized CDbased hyperbranched poly(sulfone-amine) with good complex capacity has also been reported.86
Organic nanoporous polymers have been synthesized from the cage-like CD molecules, where each CD in the polymer matrix serves as a nanosponge that can scavenge contaminants in water.87 The synthetic scheme of such polymers is shown in Scheme 2.9.
Diisocyanate
DMF, 8O oC, 24hrs
Scheme 2.9: Synthetic pathway for the formation of CD nanoporous polymers.
Efficient cross-linkers convert the molecular nanocavity into three dimensional, nanoporous polymers. By tuning the degree of cross-linking, the tailored structure results in either hydrophilic or hydrophobic polymers with "molecular hosts" that trap targeted organic compounds. Due to their strong binding and entropic effects, cyclodextrin polymers have shown the ability to remove organic compounds to very low levels of about 10-9M. However, cyclodextrin chemistry continues to offer various possibilities to synthesize polymers with different functionalities and absorption capabilities.
2.4.2.1 Thermal analysis of the CD polymers
Thermal analysis can be defined as a group of methods based on the determination of changes in chemical or physical properties of material as a function of temperature in a controlled atmosphere.88
Thermal analysis is a good analytical tool to measure the following parameters: •
Thermal decomposition of solids and liquids
Solid-solid and gas-liquid reactions
Material specification, purity and identification
Inorganic solid material adsorption
Phase transition
The principal techniques of thermal analysis are differential scanning calorimetry (DSC) and thermogravimetry analyzer (TGA). They are widely used to characterise
polymers,
compounds,
superconductors, ceramics, clays and biological materials and other common classes of compounds.89 Thermal methods have been used and are currently employed as powerful tools in the characterization of CDs and their inclusion complexes.
(a) Differential scanning calorimetry DSC measures the temperatures and heat flow associated with transitions in materials as a function of time and temperature. It determines transition temperatures, melting crystallization, and heat capacity. In this technique, Tg (material's glass transition temperature) is detected as a sharp change in the slope of the heat-capacity curve.90 Tg is the point at which a polymer changes from a solid, glassy state into a material with elastic, rubber-like behaviour.
(b) Thermogravimetric analysis Thermo gravimetric analysis is based on the measurement of weight loss of a material as a function of temperature. These changes in sample weight, which provide information about a material's thermal stability and/or composition, are reported directly as milligrams of weight change or, more commonly as a percentage weight of the samples original weight. TGA can be used to identify general types of polymers depending on the availability of a suitable standard. In
a production environment, both DSC and TGA can be used as an effective quality control tool.90 TGA and DSC have been used in characterisation of CD polymers made from HMDI and TDI.91 The table below (Table 2.2) summarises what thermal analysis can reveal about polymeric materials.
Table 2.2: What thermal analysis can reveal about polymeric materials. Characterization Analytical
technique Composition Polymer reinforcement Thermal stability Estimated lifetime
Analytical technique
crystallinity Degree and rate
of cure Addictive content,
Curing kinetics
DSC, TGA
Inclusion complexes of α- and γ-CDs with poly ethylene oxide have been characterized with DSC and TGA.92 Formation and physiochemical studies of complexes between β-CD and aliphatic guests as non-covalent amphiphiles were performed with these thermal analysis tools.93,94
Cyclodextrins can behave as molecular hosts capable of holding, a range of guest molecules via a noncovalent interaction in their hydrophobic cavities. This
phenomenon is known as a "host-guest" interaction.95 The formation of a typical inclusion complex is shown in Scheme 2.10.
+ ß-cyclodextrin (Host)
Organic compound (Guest)
Incusion complex
Scheme 2.10: Formation of an inclusion complex between the β-CD and aromatic organic compounds. The hydroxyl groups of the CD are not shown for the sake of clarity.
The interactions between CDs and organic molecules have been used as a basis for absorption and separation of various organic compounds. However, the high solubility of these cyclodextrins in water and organic solvents impose some limitations to their use as insoluble absorption media. For this reason, cyclodextrins are often converted into highly crossed insoluble polymeric material.96
Small molecules normally form 1:1 inclusion compounds. In such compounds, one CD ring includes one guest. It is also possible that the guest is only partially included by one CD. This occurs when molecules large than the cavity have to be included. When the molecule is very large, other types of inclusion compounds (e.g. 2:1) can be formed.
Persistent organic pollutants (POPs) are organic compounds that resist photolytic, biological and chemical degradation.97 They include a broad range of industrial chemicals that have been discharged to the environment. Petroleum hydrocarbons, volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), endocrine disrupting chemicals (EDCs), and phenolic compounds are some of the known examples of POPs.97 These compounds have been under investigation for many years because of their toxicity, ability to bioaccumulate and potential chronic effects to humans as well as other organisms.
Other emerging POPs that need to be specifically addressed are the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzo-furans (PCDFs).98 These compounds are not intentionally produced. They are released into the environment from various combustion processes and as a result of their occurrence as unwanted by-products in various chlorinated chemical processes. They are highly hydrophobic and very persistent in the environment. It is not surprising therefore that they have been detected regularly and frequently.99 Figure 2.5 shows examples of common POPs. A list of major sources of pollutants and their effects is outlined in Appendix D.
O2N
p-Nitrophenol
3-Methoxy phenol
4',4-Dichlorobiphenyl
2,3,7,8-Tetrachloro dibenzo-p-dioxin
Figure 2.5: Examples of structures of commonly known POPs.
Quantification of these compounds in the environment and contaminated media is key to evaluating their exposure levels and associated health risks as well as ways of removing them from the environment. Many analytical methods for the determination of POPs in water samples have been reported including the use of Gas Chromatography-Mass Spectrometry (GC/MS), UV-Visible Spectroscopy and High Performance Liquid Chromatography (HPLC).100 In addition, many treatment technology such as chemical oxidation, solvent extraction, and activated carbon adsorption were developed to remove organic compounds from domestic and industrial effluents and wastewaters. In order to comply with the stringiest environmental regulations, industries and municipal bodies must therefore be able to identify contamination resulting from chemical spills and leaks, and to monitor remediation processes.
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CHAPTER 3 EXPERIMETAL METHODOLOGY ______________________________________________________________
A series of monosubstituted cyclodextrin nanoporous polymers have been synthesized and characterized using IR and NMR spectroscopic techniques. The process entails functionalizing the primary and secondary hydroxyl groups of the parent CD compound followed by cross linking with a suitable bifunctional linker to give the desired nanoporous polymers. These polymers were tested for their ability to absorb organic compounds from water. The degree of absorption was quantified and ascertained using UV-Visible Spectroscopy and GC-MS analysis.
General procedure
TLC was performed on aluminium sheets precoated with a 0.25 mm layer of silica F254. TLC eluants used for the cyclodextrin derivatives are as follows, unless otherwise mentioned: A = 5:4:3 butanol/ethanol(95 %)/water, B = 2:1 hexane/ethyl acetate and C = 4:1 acetonitrile/water. TLC spots were visualized under an ultraviolet lamp (254 nm and/or 365 nm) or dipped in 5 % sulphuric acid (H2SO4) in ethanol followed by heating on a hot plate.
Unless specified otherwise, all NMR spectra were recorded at 300 MHz on a Varian Gemini 2000 spectrometer. Proton and carbon chemical shifts are reported in parts-per-million (ppm) using the residual signal deuterated dimethyl sulfoxide (DMSO-d6) (δ = 2.49 ppm for
H and 39.50 ppm for
C) or
trimethylsilane (TMS) (δ = 0 ppm) as the internal reference.
3.2.1.3 UV, IR and GC/MS analysis
All the Ultraviolet (UV) experiments were performed using a Varian UV-Visible Cary 50 Spectrophotometer at 25.0 ± 0.1oC. Infrared (IR) spectra were obtained from a Midac FT-IR 5000 Spectrophotometer. IR data were listed with characteristic
wavenumber
(cm-1).
CP-3800
Chromatograph coupled with Varian 2000 Mass Spectrometer was used for quantification of the organic contaminants.
All reactions were performed under nitrogen or argon pressure using pre-dried and distilled solvents. N,N-Dimethylformamide (DMF) was dried over calcium hydride for 2 days and then distilled under reduced pressure over calcium sulphate before usage. Acetone and ethanol were stored over sodium sulphate and then distilled and kept in dry molecular sieves before use. p-Toluenesulfonyl chloride was purified by recrystallization from petroleum ether prior to use.1 Unless otherwise indicated, β-cyclodextrin and all the other reagents were utilised without further purification. All other reagents and chemicals were obtained from commercial suppliers. - 44 -
As mentioned in the previous chapter, only the first three homologs of cyclodextrins (α-, β-, γ-CDs) have been extensively studied and they contain 6, 7 and 8 glucopyranose units, respectively. In this dissertation, the value of n in the structures and tables will indicate the number of glucopyranose units in the CD. Each unit of the β-CD has six linked carbon atoms and are in turn attached to hydrogen atoms and/or hydroxyl groups (Figure 3.1). The first carbon atom is labelled C-1 (often referred to as the anomeric carbon) and is bonded to a single hydrogen atom (H-1). The anomeric carbon (C-1) is easily identified by the fact that it is the only carbon linked to two oxygen atoms. The primary hydroxyl groups attached to C-6 will be denoted as OH-6 and the secondary hydroxyl groups at C-2 and C-3 position as OH-2 and OH-3, respectively.
H4 C6
O C5 C2
H1 O n
Figure 3.1: Structure of the β-cyclodextrin illustrating the numbering system used in this dissertation.
3.2.3.1 Synthesis of mono-functionalized cyclodextrins
(a) p-Toluene sulfonic anhydride (2): p-Toluene sulfonyl chloride (8.06 g, 42.0 mmol) was dissolved in dichloromethane chloride (50 mL) and p-toluene sulfonic acid (2.08 g, 10.5 mmol) was added in one portion with vigorous stirring. The resulting mixture was stirred overnight at room temperature (RT) under nitrogen. The resulting milky reaction mixture was then filtered through silica gel to remove the unreacted acid. The clear filtrate thus obtained was precipitated by the addition of hexane (200 mL). The crystals of Ts2O were collected as white needles after drying under vacuum overnight.
SO3H.H2O
O2S
1 2'
CH2Cl2
2 Scheme 3.1: Preparation of p-toluene sulfonic anhydride.
IR/KBr, cm-1: 3095 (C-H, Ar), 3058 (C-H, Ar), 2925 (C-H, Aliphatic), 1928, 1809, 1652, 1592, 1488 (SO2), 1373, 1305, 1925, 1175 (SO2), 1121, 1079, 1015. 1
H NMR, DMSO-d6: 7.75 (d, H-2, 4H), 7.36 (d, H-3, 4H), 2.49 (s, -CH3, 6H).
C NMR, DMSO-d6: 144 (C-4), 139 (C-1), 129 (C-3), 126 (C-2), 22 (C-5).
Yield: 5.89 g, 18.05 mmol, 43 %. M.pt = 124-126oC. TLC: Eluant B, Rf = 0.80.
(b). Mono-6-tosyl β-cyclodextrin (3): β-CD (2.86 g, 2.53 mmol) and p-toluene sulfonic anhydride (1.24 g, 3.80 mmol) in distilled water (62.5 mL) was stirred under inert atmosphere for 2 hours at ambient temperature. A solution of NaOH (1.25 g, 31.3 mmol) in water (12.5 mL) was then added. After 10 minutes unreacted Ts2O was removed by filtration through silica gel. The filtrate was adjusted to pH = 8 by the addition of ammonium chloride (3.36 g). Cooling overnight in the refrigerator followed by drying under vacuum afforded 3 as a white fine powder. CH3
OH O HO
NaOH/H2O
SO2 O
Scheme 3.2: Preparation of mono-6-tosyl β-cyclodextrin.
IR/KBr, cm-1: 3414 (O-H), 2929 (C-H), 1654 (C=C), 1599 (C-C), 1415 (SO2, Assy.), 1157, (SO2, Sym), 1009 (C-O). 1
H NMR/ppm, DMSO-d6: 7.76 (d, H-8, 2H), 7.44 (d, H-9, 2H), 5.71-5.52 (m, OH-
2, OH-3, 14H), 4.71 (s, H-1, 7H), 4.49-4.52 (m, OH-6, 6H), 3.76 -3.5O (m, H-6, H-3, H-5, 32H), 3.49-3.29 (m, H-4, H-2, overlap with HDO), 2.42 (s, -CH3, 3H). 13
C NMR/ppm, DMSO-d6: 146 (C-7), 133 (C-8), 130 (C-9), 128 (C-10), 102 (C-1),
82 (C-4), 73 (C-3), 72.8 (C-2), 72 (C-5), 60 (C-6), 68.0 (C-6'), 21 (-CH3). Yield = 2.25 g, 1.75 mmol, 69 %. M.pt = 172-176oC; (Lit: 174-176oC)2 TLC: Eluant A, Rf = 0.50.
(c) Mono-6-diaminoethyl β-CD (4): Well dried β-CDOTs (1.01 g, 0.783 mmol) was dissolved in DMF (20 mL) and a solution of diaminoethane (0.317 g, 1.76 mmol) and DMF (10mL) was added dropwise with constant stirring. The resulting solution was stirred for 8 hours at 70oC under argon. The resulting solution was concentrated under reduced pressure by the removal of DMF. Addition of acetone (100 mL) led to the precipitation of a yellow-brown compound which was then filtered-off. This precipitate was dissolved in water (15 mL) and the solution was poured into acetone (200 mL) to form precipitate again which was then dried under vacuum. Recrystallization from hot water yielded the title compound as a yellow-brown solid in reasonably high yields.
OTs O
H2N O
NH O
HO DMF
Scheme 3.3: Preparation of the mono-6-diethylamino β-cyclodextrin.
IR/KBr, cm-1: 3328 (O-H, N-H), 2924 (C-H), 1571, 1454, 1374, 1269, 1145, 1022 (C-O). 1
H NMR, DMSO-d6: 5.80-5.61 (m, OH-2, OH-3, 14H), 4.81 (s, H-1, 7H), 4.46 (s,
br, OH-6, 6H), 3.72-3.45 (m, H-6, H-5, H-3, N-H), 3.42-3.20 (m, H-4, H-2, -NH2, overlap with HDO), 2.07 (s, br, -CH2). 13
C NMR, DMSO-d6: 101 (C-1), 82 (C-4), 74 (C-3), 73 (C-2), 73 (C-5), 67.5 (C-6'),
59 (C-6), 54 (C-7), 48 (C-8). Yield: 0.63 g, 0.528 mmol, 67 %. M.pt = 192-195oC (dec). TLC: Eluant A, Rf = 0.58.
(d). Mono-6-acetyl β-cyclodextrin (5): β-CD (3.01 g, 2.64 mmol) was dissolved in DMF (50 mL) and acetyl chloride (0.19 mL, 2.64 mmol) was added dropwise. On dropwise addition of diisopropylamine (0.45 mL, 2.64 mmol) to the stirred reaction mixture, the colour changed immediately to yellow-brown. This solution was stirred for 2 hours at -30oC under a stream of argon gas. The mixture was then left to stand at RT for a further 14 hours under a weak stream of argon gas. The resulting solution was concentrated under reduced pressure to about 20 mL. Dichloromethane (CH2Cl2) (200 mL) was added to the resulting white precipitate. The precipitate formed was filtered off, washed with CH2Cl2 and dried under vacuum to yield a white solid material.
DM F
diisopropylam ine
Scheme 3.4: Preparation of the mono-6-acetyl β-cyclodextrin.
IR/KBr, cm-1: 3384 (O-H, br), 2925 (C-H, sharp), 1651 (C=O), 1406, 1157, 1032 (C-O), sharp), 937, 750-601 (weak). 1
HNMR/ppm, DMSO-d6: 5.72 (d, OH-2, 7H), 5.67 (s, OH-3, 7H), 4.81 (s, H-1,
7H), 4.46 (s, H-6, 6H), 3.61-3.47 (m, H-3, H-5, H-6), 3.39-3.22 (m, H-4, H-2), 2.07 (s, CH3, 3H). 13
C NMR, DMSO-d6: 162 (C-7), 102 (C-1), 82 (C-4), 73 (C-3), 72.5 (C-2), 72.1 (C-
5), 60 (C-6), 60 (C-6'), 34 (C-8). Yield: 2.30 g, 1.95 mmol, 74 %. M.pt. = 160-164oC (dec.). TLC: Eluant C, Rf = 0.76.
(e). Mono-2-benzoyl β-cyclodextrin (6): β-CD (2.00 g, 1.76 mmol) was dissolved in DMF (20 mL) and NaH (0.063 g, 2.64 mmol) was added with stirring. The reaction was left stirring overnight at room temperature. Benzoyl chloride (0.31 mL, 0.372 g, 2.64 mmol) was then added to the resulting clear solution. The reaction was stirred for a further 24 hours at room temperature under nitrogen gas. Addition of acetone (100 mL) precipitated the title compound which was then filtered. After drying under vacuum white solid granules were obtained. OH O OH O HO
HO Cl
OH O n
Bz =
Scheme 3.6: Preparation of the mono-2-benzoyl β-cyclodextrin.
IR/KBr, cm-1: 3382 (O-H), 2926 (C-H), 1660 (C=O), 1554, 1403, 1308, 1232, 1016(C-O). 1
H NMR, DMSO-d6: 7.56 (d, H-8, 2H), 7.40-7.44 (m, H-10), 7.22 (d, H-9, 2H),
5.56-5.80 (m, OH-2, OH-3, 13H), 4.81 (s, H-1, 7H), 4.30 (d, OH-6, 7H), 3.41-3.72 (m, H-6, H-5, H-3), 3.37-3.21 (m, H-4, H-2, overlap with H2O). 13
C NMR, DMSO-d6: 157.6 (C=O), 144.8 (C-7), 132.6 (C-8, C-8'), 129.9 (C-10),
127.6 (C-9), 125.5 (C-9'), 101.9 (C-1), 81.5 (C-4), 73.1 (C-3), 72.4 (C-2), 72.4 (C2'), 72.0 (C-5), 59.9 (C-6). Yield: 1.27 g, 1.02 mmol, 58 %. M.pt = 188-190oC (dec). TLC: Eluant A, Rf = 0.68. - 50 -
(f). Mono-2-methyl β-cyclodextrin (7): β-CD (2.01 g, 1.76 mmol) was dissolved in DMF (20 mL) and NaH (0.063 g, 2.64 mmol) was added in one portion with stirring. This resultant milky solution was left overnight at room temperature. Methyl iodide (0.16 mL, 0.375 g, 2.64 mmol) was added to this oxyanion. The reaction was stirred for a further 24 hours at 70oC under argon gas. DMF was then concentrated under vacuum, followed by addition of acetone (100 mL) and suction filtration. After washing with acetone, drying and recrystallization from hot water, a white fine powder of the desired CD derivative was obtained in a yield of 49 %.
CH3I
OMe O
Scheme 3.5: Preparation of the mono-2-methyl β-cyclodextrin.
IR/KBr, cm-1: 3380 (O-H), 2919 (C-H), 1651 (C-C), 1406, 1157, 1032 (C-O), 937, 750-601. 1
H NMR, DMSO-d6: 5.51 (d, OH-2, 6H), 5.44 (s, OH-3, 7H), 4.79 (s, H-1, 7H),
4.48 (s, OH-6, 7H), 3.76-3.73 (m, H-5, 7H), 3.63-3.56 (m, H-6, H-3, 14H), 3.403.26 (m, H-4, H-2, 21H), 1.23 (s, -CH3, 3H). 13
C NMR, DMSO-d6: 102.5 (C-1), 82.2 (C-4), 73.5 (C-3), 72.9 (C-2'), 72.4 (C-5),
69.5 (C-2), 60.4 (C-6), 53.8 (-CH3).
Yield: 1.01 g, 0.870 mmol, 49 %. M.pt = 205-207oC. TLC: Eluant A, Rf = 0.38. - 51 -
(g). Mono-2-allyl β-cyclodextrin (8): β-CD (2.00 g, 1.76 mmol) was dissolved in DMF (20 mL) and NaH (0.063 g, 2.64 mmol) was added in one portion with stirring. The reaction was stirred vigorously under a weak stream of argon at room temperature overnight. Allyl bromide (0.319 g, 0.23 mL, 2.64 mmol) was then added to the resulting clear solution and the temperature was raised to 55oC. After 5 hours acetone (200 mL) was added to precipitate the allyl derivative. The white paste formed was then filtered off and washed further with large quantities of acetone to remove residual DMF followed by drying under high vacuum. OH O HO
Allyl bromide
NaH n
Scheme 3.7: Preparation of the mono-2-allyl β-cyclodextrin.
IR/KBr, cm-1: 3377 (O-H), 2929 (C-H), 1637 (C=C), 1599 (C-C), 1406, 1151, 1037 (C-O), 943, 571. 1
HNMR/ppm, DMSO-d6: 5.42 - 5.58 (m, OH-2, OH-3), 5.68m (allyl), 5.27 (dd),
5.18 (dd), 4.80 - 4.95 (dd, H-1), 4.42 - 4.89 (m, OH-6), 4.28 (dd), 4.16 (dd), 3.74 - 3.77 (m, H-3, H-6), 3.50 - 3.64 (m H-5), 3.28 - 3.41 (m, H-2, H-4). 13
C NMR, DMSO-d6: 135.6 (C-8), 114.5 (C-9), 101.9 (C-1), 81.3 (C-4), 73.5 (C-
3), 72.9 (C-2), 73.6 (C-2') 72.4 (C-5), 71.8 (C-7), 60.3 (C-6).
Yield: 0.75 g, 0.638 mmol, 36 %. M.pt = 268-270oC (dec.). TLC: Eluant C, Rf = 0.50.
(a) General procedure for preparation of diisocyanate polymers
A DMF solution of each monofunctionalized CD (4, 5, 6, 7 and 8) was typically reacted with a bifunctional linker such as hexamethylene- and toluene-2,4diisocyanates in a 1:8 molar ratio. The solution was heated at 70oC for 24 hours under inert conditions. Filtration followed by washing of the resulting material with copious amounts of acetone to remove residual DMF led to the isolation of an insoluble solid material. These were then dried overnight under high vacuum to produce the target polymers (Figure 3.2 and 3.3) in almost quantitative yields. O
Figure 3.2: The structure of a monofunctionalized CD hexamethylene diisocyanate polymer.
H H3C
Figure 3.3: The structure of a monofunctionalized CD tolune-2,4diisocyanate polymers.
(b) General procedure for the preparation of Adipoyl dichloride polymers
A DMF solution of the monofunctionalized CDs (4, 5, 6, 7 and 8) was left to react overnight with NaH in a 1:8 molar ratio overnight at room temperature, followed by the addition of adipoyl dichloride in a similar ratio. After adding adipoyl dichloride (similar ratio) to the reaction mixture, the resulting mixture was stirred vigorously at 70-80oC for 24 hours under argon gas. The polymeric material was precipitated by the addition of large amounts of acetone, followed by filtration and washing of the resulting material several times with acetone. These desired insoluble polymers (Scheme 3.8) were obtained in quantitative yields after drying overnight under vacuum.
O RO
NaH, DMF adipoyl dichloride
Scheme 3.8: Representative scheme for the preparation of adipoyl chloride polymers.
(c) General procedure for the preparation of epichlorohydrin polymers
A mixture of 1.00 g of CD derivative (4, 5, 6, 7 and 8) in 10 % of NaOH solution (5 mL) was stirred overnight at RT. The mixture was heated at 30oC and epichlorohydrin (EPC) (8 molar equivalents) was added immediately. During the polymerisation the temperature was monitored and kept at 30oC with constant stirring. After 4 hours, acetone (100 mL) was added and the precipitate formed
was filtered off. The pH of the solution was then reduced by the addition of a few drops of HCl (6 N). The resulting solution was then kept overnight at 50oC. After cooling, the solution was neutralized again with HCl (6 N) and filtered off. The insoluble granular solid obtained was washed with acetone (100 mL) followed by filtration and drying. A scheme for such a reaction is shown below.
OH RO
NaOH/H2O Epichlorohydrin
Scheme 3.9: Scheme for the preparation of epichlorohydrin CD polymers.
DSC analyses of the polymers were carried out on Mettler Toledo DSC 822e Analyzer with a heating rate of 10oC/min in the temperature range 50-500oC. An empty sample pan was used as an inert reference. The TGA analyses were carried out on a Perkin Elmer instrument with a heating rate of 10oC/min in the temperature range 50-800oC in nitrogen gas.
These instruments allow for the monitoring of thermo-chemical events and weight loss as a function of temperature as well as the decomposition of glucose in the polymer. They also provide valuable insights into the degradation pathways of the polymers.3 In particular, DSC allows for better identification of melting points and glass transition temperatures.
All the polymers formed were insoluble in water, a very important attribute for polymers intended for use in the removal of organic pollutants from water. An investigation of the absorption capability of these polymers was also carried out. This was accomplished by performing model contamination experiments. Such experiments involved deliberately placing solid nanoporous polymers into an aqueous solution containing known concentration of organic pollutants. Quantification of the organics was achieved by UV- Visible Spectroscopy and GC-MS analysis.
3.4.1 UV Absorbance experiments A CARY 50 UV Spectrophotometer was used to measure the UV absorbance of p-nitrophenol (PNP) samples before and after treatment of standard solutions with the monofunctionalized CD polymers. A 10mm quartz cuvet cell was used. The instrument was calibrated with PNP standards and the calibration curve used to determine the concentrations of the pollutant absorbed by the polymers. The method used is as described by Environmental Protection Agency (EPA) method 5910B of the Standard Methods for the Examination of Water and Waste Water (1989).
p-Nitrophenol is highly soluble in water and can easily be monitored by UVvisible spectroscopy. Water samples containing known concentrations of PNP were prepared by dissolving the pollutant in deionized water. Standards of the following concentrations were then prepared: 20 mg/L, 15 mg/L, 10 mg/L, 5 mg/L
and 2.5 mg/L and used to plot a calibration curve. Each polymer (300 mg) was then mechanically stirred together with a 100 mL of the 10 mg/L PNP sample. At 10 mg/L the yellow colour of PNP was observed with the naked eye. After 30 minutes, the polymer which had then assumed the colour of the PNP was filtered off and the absorbance of the filtrate was taken at the maximum absorption wavelength of PNP (λ = 318 nm). The concentration after absorption for each polymer was computed from the equation y = mx + c.
The GC/MS is one of the so-called hyphenated analytical techniques.4 As the name implies, it comprises two techniques that are combined to form a single method of analysing mixtures of compounds. Gas Chromatography (GC) separates the components of a mixture and Mass Spectrometry (MS) characterizes each of the components individually. By combining these two techniques, an analytical chemist can both qualitatively and quantitatively evaluate a solution containing a number of compounds. This technique is widely used in the medical, pharmacological and environmental fields. In this project, GC/MS is used to evaluate water samples containing the organic compound (pentachlorophenol).
3.4.2.2 Operating principles for the GC/MS In all chromatography, separation occurs when the sample to be analysed is introduced (injected) through an injector port into a mobile phase. In Liquid
Chromatography (LC), the mobile phase is a solvent while in GC the mobile phase is a gas. Helium gas was used as a carrier gas in all experiments in this study. This gas sweeps the analyte into the column where the separation occurs. As the compounds are separated, they elute from the column and enter the detector which creates a signal whenever the presence of a compound is detected.5 The time from when the injection is made (time zero) to the time when elution occurs is referred to as the retention time (TR). Compounds that have similar properties often have similar retention times. Therefore, more information is usually required before an identification of a compound containing a sample can be made. As individual components elute, they are bombarded with a stream of electrons causing them to break apart into fragments. These fragments are actually charged ions with a certain mass. Neutral fragments are also formed but they are not detected by this technique. The mass of the fragments divided by the charge is called the mass to charge ratio (m/z). The mass spectrum produced by a given chemical compound is essentially the same every time. Therefore, the spectrum is the finger print for the molecule which can be used to identify the compound. A library of spectra can be used to identify an unknown chemical by comparing the mass spectrum of a sample component with the mass spectra of compounds having similar m/z and fragmentation pattern. It reports a list of possible identifications with the statistical probability of the match. An MS data handling method for the MS was used for the quantification of spectral peaks.
3.4.2.3 Procedure for the preconcentration of water samples
At very low levels of concentrations, it is important to preconcentrate water samples before analysis. Water samples are preconcentated so that they can be within the detection limit of the analytical instrument used and also to ensure purity of the samples to be analysed.
The method used for this procedure was Method 525.2, an EPA method for analysing semi-volatile organics.6 This is a drinking water method for the determination of a wide range of semivolatile organic compounds including PAHs, pesticides and PCBs. It uses solid phase extraction for isolation and concentration; and GC/MS for determination. EPA Method 525.2 is performed by loading a 1000 mL of water onto a conditioned C-18 Solid phase extraction (SPE) cartridge. The cartridge is then dried and eluted with a combination of ethyl acetate (EtOAc) and dichloromethane (CH2Cl2). The extract is dried by passing it through 5-7 g of fired sodium sulphate and concentrated to about 1mL.
The SPE method generally comprises four steps. The first step is conditioning of the column with methanol. In the second step the sample is loaded in the solid sorbent. The third step consists of washing of the sorbent with a solvent that has a low elution strength and the final step involves the elution of the desired analyte with a suitable solvent. Tables 3.1 and 3.2 describe the extraction procedures of EPA Method 525.5.
Table 3.1: A summary of the loading procedures. Step
Loading Procedure
Flow Rate (mL/min)
Wash syringe with 2 mL of MeOH
Load Flow
Rinse column with 5 mL of EtOAc into solvent waste
Rinse Flow
Rinse column with 5 mL of CH2Cl2 into solvent waste
Elute Flow
Condition column with 10 mL of MeOH into solvent
Cond. Air
Condition column with 10 mL of Water into aqueous waste
Load 500 mL of sample onto column
Dry column with gas for 10 min
Rinse air push
Elute air push
Table 3.2: A summary of the eluting procedures. Step 1
Eluting Procedure
Manually rinse sample container with 7 mL to collect Manually rinse sample container with 10 mL to collect Soak and collect 3 mL fraction using EtOAc Collect 2 mL fraction into sample tube using EtOAc Soak and collect 3 mL fraction using CH2Cl2 Collect 2 mL fraction into sample using CH2Cl2 End
Cond. Air push
Due to the malfunctioning of the Zymark Autophase SPE work station, a modified SPE was constructed in our laboratory.18 This involved connecting a 500 mL separatory funnel, a C-18 SPE cartridge, and an Erlenmeyer flask that was connected to a sunction pump for enhancing smooth flow of water samples passing through cartridge (Figure 3.4). This new SPE however, led to the adjustment of the procedures involved in Method 525.2. For an instance, the volume of water samples used was 500 mL instead of 1000 mL.
500 mL Separatory funnel
C-18 SPE cartridge
To sunction pump Collecting Flask
Figure 3.4: Diagram showing the modified SPE used in this project.
The C-18 SPE cartridge was then emptied and packed with CD polymer granules (500 mg) and pentachlorophenol water samples were loaded onto the column. The contaminated samples that passed through the column were then collected in 10 mL vials (instead of the 1 mL originally used by SPE) and re-extracted through the C-18 SPE cartridge followed by quantification by GC/MS. This is summarized in Table 3.3.
Table 3.3: Procedure for absorption by SPE method. Step 1 2 3
Loading and eluting procedure Load 500 mL of sample onto cartridge packed with CD polymer Dry with gas for 15 minutes Soak and collect 5 mL fraction into sample tube using EtOAc Soak and collect 5 mL fraction into sample tube using CH2Cl2
Flow rate (mL/min) Load flow
3.4.2.4 Preparation of PCP samples In order to study the efficiency of the polymers in the removal of pentachlorophenol (PCP) from an aqueous medium at µg/L levels, we prepared 100 µg/L water samples. Since PCP is fairly soluble in water it was first dissolved in very small amounts (approximately 1 mL) of ethanol before the addition of deionized water. The samples were then sonicated for a few minutes to ensure a homogenous solution. Standards for the samples used in calibration were prepared in a similar way using dichloromethane. Approximately 1 µL was
injected into the GC/MS injector port. The areas of the peaks obtained in the GC/MS were used to calculate the concentrations of the samples before and after absorption by the polymers.
In this study, GC/MS analyses were carried out using a Varian 3800 capillary gas chromatography coupled with a Saturn 2000 mass spectrometer. EPA Method 8270 was used to determine the concentration of semi-volatile organic compounds in extracts prepared from the water samples.7 This method uses similar conditions to method 525.2 except that it is most suitable for determination of phenol and its derivatives which were selected as target compounds in the study. Method 525.5 is developed mainly for the determination of pesticides. The operating conditions for the EPA method 8270 (GC/MS) for each experiment are shown in Table 3.4.
Table 3.4: Operating conditions for EPA Method 8270 for determination of semivolatile organic compounds. Entry
Injection mode and volume
1µl splitless (hold 0.4 min.)
Capillary Chrompack CP Sil 8 CB, 30 m 0.25 mm ID, 0.25 µm
Injector temperature
40-300°C
Carrier gas
Helium, constant flow
1mL/min
Oven temperature
35°C (hold 2 min.) to 260°C at 20°C/min, to 330°C at 6°C/min (hold 1 min.)
Mass Spectrometer (Ion trap)
Transfer line temp.
Mass range
35-550 amu
Electron ionization (EI)
Full scan
8. Armarego W.L. F., Perrin D.D. (1996), Purification of Laboratory Chemicals, 4th Edition, Oxford. 9. Peter R.C., Salek J.S., Sikorsky C.T., Kumaravel G., Lin F.T., J. Am. Chem. Soc. 112 1990 3860. 10. Brown M.E. (1988), Introduction to Thermal Analysis: Techniques and Applications. Chapman and Hall: London. 11. McMaster M., McMaster C. (1998), GC/MS: A Practical User's Guide, 1st ed. USA: Wiley-VCH. 12. Smith M.R., Busch K.L. (1999) Understanding Mass Spectra: A Basic Approach. USA: John Wiley and Sons, Inc. 13. Application Brief (2001) Method 525.2, Semi-volatile Organics in Water by Solid Phase Extraction and GC/MS Detection, Zymark Corporation. 14. Chromspec cc. Chromatography Products (2004/2005). EPA Method 8270 – Semivolatile Organics, pp 584.
CHAPTER 4 RESULTS AND DISCUSSION
Nuclear magnetic resonance (NMR) spectroscopy has been widely used in the characterization of cyclodextrins and their derivatives. Therefore, NMR analysis of the unmodified β-cyclodextrin was very useful in determining whether the substituents were incorporated onto the parent CD skeleton.
The secondary hydroxyl groups of the parent β-cyclodextrin at the greater rim of the CD, form intramolecular bonds in which the OH-3 group of one glucose unit interacts with the OH-2 group of the neighbouring glucose unit (Figure 4.1).1
Primary hydroxyl group OH
O-H
Secondary hydroxyl groups
Figure 4.1: Structure illustrating details of the hydroxyl groups (OH-2 and OH-3) which participate in the formation of intramolecular bonds.
This leads to a belt of hydrogen bonds around the secondary hydroxyls that gives the whole molecular structure a rather rigid configuration. The primary
hydroxyls placed at the smaller rim are not contributing to the intramolecular hydrogen bonding, and thus they can rotate partially blocking the hydrophobic cavity of the CD. Protons involved in the hydrogen bonding are much more deshielded than the free-rotating protons, and therefore appear in different regions of the 1H-NMR spectrum.2 Figure 4.2 shows the chemical shifts of the protons in the unsubstituted β-CD in deuterated dimethyl sulfoxide (DMSO-d6).
OH O n n=7
Beta-cyclodextrin HDO
H-6, H3, H-5
H-4, H-2
Figure 4.2: 1H NMR spectrum of unsubstituted β-cyclodextrin in DMSO-d6 (in ppm).
The resonances of OH-3 and OH-2 were found to appear at 5.67 ppm and 5.72 ppm respectively. These were clearly separated from the triplets of the free and less deshielded OH-6 groups that appear at 4.46 ppm. All the other protons, except the doublet of the anomeric protons (H-1) appearing at 4.81 ppm, are
found in the region 3.25-3.67 ppm. The anomeric protons are more deshielded because they are attached to carbon atoms which are bonded to two electronegative (oxygen) atoms. The H-3 and H-5 protons are located within the cavity of the CD and are thus, as shown in the spectrum, more deshielded than the H-2 and H-4 which are located on the exterior of the cavity. 13
C NMR chemical shifts of CDs (Figure 4.3) extend over a larger range than
proton shifts and are especially suitable and useful for identifying these starchbased compounds and their derivatives. While the anomeric C-1 carbon is highly deshielded (102 ppm) than the rest of the carbon atoms; the C-6, found at 59.9 ppm, is highly shielded. Carbons C-2 and C-3 as well as C-5 are located in the region: 72 ppm to 73 ppm. However, C-4 is clearly separated from these carbon atoms and is found at 82 ppm. The signals found in the region, 39 - 40 ppm, were assigned to the solvent peak (DMSO peak).
n=7 B e ta -c yc lo d e x trin
C-2 C-5 C-3
C-4 C-1
Figure 4.3: 13C NMR spectrum of unsubstituted β-CD in DMSO-d6.
4.2 Characterization of mono-functionalized β-CD derivatives
In this study, we looked at monofunctionalization of two differently substituted CDs i.e. at the 6-position and the 2-position. Monofunctionalization at the 3position was not considered in this study, since the C-3 hydroxyls are the most inaccessible, least reactive and sterrically hindered among the three types of OHs present in the exterior surfaces of the CD. The monofunctionalization reactions at 2- and 6-positions are discussed individually below.
As highlighted before, CD monotosylates are generally important precursors for a variety of modified CDs because nucleophiles can attack the electrophilic carbon at the 6-position to produce the corresponding functionalized derivatives. Monotosylation of the CD can be achieved using either tosyl chloride or tosyl anyhydride. The anhydride method was adopted in this study for the monotosylation of the CD. This method is less complicated and affords the target compound in superior yields when compared to the tosyl chloride method. In addition, the p-toluene sulfonic anhydride Ts2O is more stable than p-toluene sulfonyl chloride.3
Either water or pyridine can be used when performing tosylation using the anhydride. We decided to use water since pyridine is toxic and requires dry conditions. Pyridine also has added disadvantage of leading to the formation of an adhesive gel thus rendering stirring impossible during the course of the reaction.4 In addition, formation of a mixture of compounds cannot be avoided when pyridine is used as a solvent.
(a) Synthesis and characterization of Ts2O
Before tosylation could be attempted we first had to synthesize p-toluene sulfonic anhydride. This compound was synthesized in satisfactory yields (43%) by the reaction of p-toluene sulfonyl chloride and the monohydrate of sulphonic acid at ambient temperature.
Successful formation of the starting material was
confirmed by IR and NMR spectroscopy. The
H NMR spectrum of Ts2O
(outlined in Appendix A) showed the aromatic and methyl signals at the expected regions (7.75-7.36 ppm and 2.49 ppm, respectively). Similarly, the
NMR spectrum shows an AB system of the aromatic carbons i.e. two sets of carbon atoms: C-1 and C-4 at 139 and 144 ppm, respectively, and C-3 and C-2 at 129 and 126 ppm, respectively. The methyl carbon was observed at the expected region (22 ppm). This is depicted in Figure 4.4.
O 2S 2 3
SO2 2' 3'
p-Toluene sulfonic anhydride
Figure 4.4: 13C NMR (DMSO-d6) spectrum of p-toluene sulfonic anhydride.
(b) Synthesis and characterization of the monotosylate The monotosylation at the primary side was accomplished (69% yield) by treatment of the β-cyclodextrin with p-toluene sulfonic anhydride in an alkaline solution at room temperature. Apparently, this reaction is accompanied by the formation of an inclusion complex between the Ts2O and the CD moiety before the addition of NaOH solution.5 The structure of the mono-6-tosyl β-cyclodextrin (shown in Figure 4.5) was confirmed by 1H and
C NMR spectroscopy as well as IR spectroscopy. The 1H
NMR spectrum of the monotosylate precursor showed in the aromatic region the characteristic pattern of a tosyl system (two set of doublets at 7.76 ppm and 7.44 ppm). Both doublets integrated for 2 protons which is equivalent to the total number of protons (four) available in the aromatic loop of the tosyl group. The location of these peaks in the 1H NMR spectrum is approximately the same to literature data (7.73 ppm and 7.42 ppm).6 A singlet found at 2.42 ppm was ascribed to the three methyl protons of the tosyl group. The 6-hydroxyl substitution was also confirmed by the reduction in the integration of the peak due to the hydroxyl protons in position 6 (OH-6) at 4.49-4.52 ppm.
C H3
OH SO 3
Figure 4.5: The structure of mono-6-tosyl-β-cyclodextrin.
According to Breslow,7 the carbon linked to the tosyl group appears downfield relative to the unsubstituted carbon. This was confirmed by the appearance of the C-6' and C-6 signals at 68 ppm and 59.9 ppm, respectively (Table 4.1). The structure was further confirmed by the emergence of aromatics peaks at 145 ppm, 133 ppm, 130 ppm and 128 ppm. The peak of the methyl carbon attached to the aromatic ring appears at 21.2 ppm. All these values are relatively the same to a previous report.8 The NMR spectra for this compound are outlined in
Appendix A.
Table 4.1: 13C NMR chemical shifts of carbon in mono-6-tosyl β-CD.. Carbon atom δ/ppm
-CH3
Furthermore, the IR spectra showed the S=O asymmetric and symmetric stretches at 1295 cm-1 and 1157 cm-1, respectively. The melting point (172-176 o
C) and Rf value of this classic compound are in agreement with literature
values.9
4.2.2.1 Mono-6-diethylamino β-CD
Treatment of recrystallized β-CDOTs with diaminoethane in DMF at elevated temperatures led to the formation of the diethylamino CD derivative 4. Typically, the cyclodextrin tosylate was dissolved in small amounts of DMF, followed by dropwise addition of the amine. Thereafter, the reaction mixture was stirred
under argon at 70 oC for 8 hours. Recrystallization in hot water afforded this compound in good homogeneity and in satisfactory yields (67%) which compares favourably to the 65% yield obtained by previous researchers.10
In this reaction, the tosyl group is displaced through nucleophilic substitution by the diaminoethyl group. The complete disappearance of the tosyl group in the aromatic region of both the 1H (7.76 ppm and 7.44 ppm) and
C NMR (128 to
145 ppm) spectra provided evidence for CD amination. Other important peaks observed from the 1H NMR spectrum were as follows: a singlet at 4.81 ppm assigned to the anomeric protons, a new singlet at 2.07 ppm assigned to the methylene protons of the diaminoethyl group. The N-H signals are thought to be embedded in the multiplet featuring in the region 3.72-3.45 ppm. The carbon NMR chemical shifts of this compound are listed in Table 4.2.
C NMR chemical shifts, δ (ppm), of carbon in mono-6-
diaminoethyl β-CD in DMSO-d6. Carbon atom δ/ppm
NH-C NH2-C
101.1 72.81 72.84 81.9 73.7 59.2 67.5 54.1
The NMR data in the table above reveals that there are two additional carbon atoms at 54.1 ppm and 48.3 ppm which were introduced during the synthesis of compound 4. These signals were assigned to the NH-C and NH2-C of the diaminoethyl group in that order. The resonances of C-1 to C-5 were not greatly affected. However, the resonance of the substituted carbon (C-6') at 67.5 ppm was greatly shifted. This fact constituted evidence that the substitution occurred on the primary hydroxyls of the CD macrocycle.
4.2.2.2 Mono-6-acetyl β-CD
The acetylating method was adopted with minor modifications from a previous procedure.11 The method involved the reaction of a DMF solution of β-CD with acetyl chloride (as an acetylating reagent) in the presence of a hydrogen chloride acceptor (diisopropylamine). The reaction was performed at very low temperatures (-30 oC) under a weak stream of argon gas.
Figure 4.6: The structure of mono-6-acetyl- β-cyclodextrin.
Yet again, it was easily concluded from the IR and NMR spectra that the acetyl group was successfully incorporated onto the CD backbone, in the 6-position (Figure 4.6). The appearance of a sharp strong peak (1651 cm-1) and a small signal at 162 ppm in the respective IR and
C NMR spectra of the target
compound were identified as the carbonyl group (C=0). In addition, there was a new carbon peak at 34 ppm which was inferred to the methyl carbon of the acetyl group. Once again, carbon signals of the CD backbone (C-1 to C-5) were not significantly affected. The singlet peak for the OH-6 at 4.46 ppm integrated for 6 protons, while the secondary hydroxyl groups (OH-2 at 5.72 ppm (d) and OH-3 at 5.67 ppm (s)) integrated for 7 protons each. This confirmed that the substitution had occurred at the 6-position of the CD.
As noted earlier, the C-2 hydroxyl groups are more acidic than the C-6 hydroxyl groups. This characteristic was exploited by using sodium hydride (NaH) as a strong base under anhydrous conditions to deprotonate the C-2 secondary hydroxyl groups of the CD macrocycle. Generally, the reaction involved dissolving the CD in small amounts of DMF, followed by the addition of small amounts of the deprotonating reagent (Scheme 4.1). The resultant milky mixture was then stirred vigorously at room temperature for 1 day in an inert atmosphere.
NaH DMF 2
Scheme 4.1: The deprotonation reaction of the C-2 OHs of the β-CD.
Addition of benzoyl chloride to the oxyanion produced the corresponding ester 6 at a yield of 58%. The aromatic signals in the region 7.40-7.44 ppm (multiplet) and two doublets at 7.22 ppm and 7.56 ppm (representing all the other aromatic protons of the ring) were observed in the 1H NMR spectrum. The anisotropic effects associated with the carbonyl group are responsible for the deshielding of the aromatic protons at C-8 and C-8' of this compound. The broad multiplet appearing in the region 5.56-5.80 ppm integrated for 13 protons and was interpreted as the OH-2 and OH-3 protons.
Successive appearance of the aromatic carbon peaks at five different regions in the
C NMR spectrum accounted for all the carbons including the quaternary
carbon (126 ppm, 128 ppm, 130 ppm, 133 ppm and 145 ppm). This confirmed successful incorporation of the benzoyl group. There is no doubt that the benzoyl group was successfully built into the backbone of the CD in the 2-position. A carbonyl (C=O) peak was observed in the IR and
C NMR spectra at 1660 cm-1
and 157.6 ppm, respectively. This evidence was adequate to confirm successful synthesis of this white CD derivative. The addition of methyl iodide to the deprotonated CD yielded the methyl ether 7 at less satisfactory yields (49%) under non-optimized conditions. The proton NMR chemical shifts of this compound are almost similar to those of the unmodified CD. However, in the upfield region, there is a small singlet at 1.23 ppm which integrated for 3 protons and was assigned to the methyl group. In addition, there was a slight integral change in the OH-2 of the methylated CD in comparison to the primary hydroxyl groups. The
C NMR spectrum shows an
additional peak at δ = 53.8 ppm assigned to the methyl group carbon. Monomethylation of the β-CD was, therefore, successfully achieved.
Finally, the treatment of the CD oxyanion with allyl bromide yielded the allyl derivative 8 in a yield of 36% after workup. 9 8
NaH Allyl bromide 6
Scheme 4.2: Synthesis of mono-2-allyl β-CD.
As the 1H NMR data of this compound showed signals of impurities, it may be necessary to further establish the purity of this material. While assignment of some peaks in the 1H NMR spectrum was ambiguous, characteristic allyllic peaks in the
C NMR spectrum were spotted at the expected regions (136 ppm (C-8),
115 ppm (C-9) and 72 ppm (C-7)). These values corresponds with the literature values, which are 134.8 ppm, 117.7 ppm and 72.4 ppm, respectively.12
monofunctionalized
synthesised
successfully and produced at reasonably high yields and were, as shown in
Table 4.3, obtained either as powders or solid granules.
Table 4.3: Yields and physical appearances of the β-CD derivatives synthesized. CD derivative
Melting points (oC)
Colour and form
Yield (%)
White fine powder
192-195 (dec.)
Yellow-brown solid
White solid material
White fine powders
White solid granules
6-CDOTs:Mono-6-tosylCD, 2-CDOAllyl:Mono-2-allylCD, 2-CDOBz:Mono-2-benzoylatedCD, 6CDOAc:Mono-6-acetylCD,
2-CDOMe:Mono-2-methylCD,
*Dec = the material was decomposing at its melting point.
6-CDOAm:Mono-6-diaminoethylCD.
The melting points of these CD derivatives are not significantly different with the exception of 2-CDOAllyl and 2-CDOMe, which exhibit melting points above 200 o
C. Such melting points are similar to those of the unfunctionalized β-cyclodextrin
molecule (290-300 oC). Whilst most of the CD derivatives decomposed at their melting points, 6-CDOTs and 2-CDOMe were obtained as white fine powders and were not accompanied by decomposition. The successful preparation of these modified CD compounds in such good yields (36-74%) allowed us to prepare polymer derivatives using complementary bifunctional linkers.
4.3 Synthesis and characterization of the monofunctionalized CD polymers
Cyclodextrin chemistry continues to present an assortment of possibilities to produce diverse derivatives, including polymers, with different functionalities. Efficient cross-linkers convert the parent CDs into three dimensional, nanoporous polymers. The degree of cross-linking can be fine-tuned to give either hydrophilic or hydrophobic polymers with "molecular hosts" that can trap targeted organic compounds.
Cross linkers used in this research work have been successfully employed in our laboratory and elsewhere to synthesize insoluble cyclodextrin polymers from the corresponding monofunctionalized β-cyclodextrins. The linkers utilized in this study were hexamethylene diisocyanate (HDI), toluene-2,4-diisocyanate (TDI), adipoyl dichloride (ADP) and epichlorohydrin (EPC) and their structures are shown in Figure 4.7.
O C
C O
O Cl Cl
Adipoyl dichloride
Figure 4.7: The structures of the linkers used to synthesize polymers.
All the polymers formed are insoluble in water and it was impossible to do the characterization of these compounds with the NMR instruments at our disposal. NMR characterization can only be achieved by solid state NMR spectroscopy.13 Characterization was however performed by IR spectroscopy. The polymers were prepared by adding HDI or TDI to a DMF solution of the monofunctionalized CD. The resulting solution was then stirred at elevated temperatures (Scheme
4.3). Large amounts of acetone were added to precipitate the polymers and this was followed by filtration and drying of the resulting polymer. O
HDI DMF, 7O-80
H oC,
Scheme 4.3: Synthetic scheme for a monofunctionalized CD polymer prepared from HDI.
Figure 4.8 shows the disappearance of the isocyanate peak at 2270 cm-1, which was used as a control for monitoring the progress of the polymerization reactions. 100
Transmittance (%)
isocyanate peack (2270 cm )
Wavenumbers (cm ) Figure 4.8: The IR spectra illustrating the disappearance of the isocyanate peak during the formation of the mono-2-benzoylated CD polymer prepared from HDI; (a) CD/HDI/DMF solution after 1 hour, (b) CD/HDI polymer after 24 hours.
It is observed from the spectra above that the diisocyanate peak was visibly prominent after an hour (a), but was reduced significantly as the reaction progressed. After 24 hours of reaction (b) with the CD derivative the peak had completely disappeared. The development of vibration bands at 3370 cm-1 (N-
H), C=O at 1610 cm-1 and NH-CO groups at 1500 cm-1 also confirmed the successful synthesis of the derived nanosponges. The broad peak in the range of 3250-3540 cm-1 represents the O-H and N-H stretching. The synthesis and characterization of other HDI and TDI-linked derivatives were carried out in a similar manner. It is important to note as well that the isocyanate peak for TDI appears at the same wavelength as that of HDI (2270 cm-1).
Several main absorption bands were observed at different wavenumbers for the various nanosponges and were interpreted as follows. A wide band was observed in the region 3550-3275 cm-1 in the spectra of 6-CDOAm/TDI and 6CDOAm/HDI. This broad band was attributed to the O-H and N-H stretching and its width was ascribed to the formation of inter and intramolecular hydrogen bonds. This is indicated in Figure 4.9. Furthermore, the strong band at 1675 cm-1 was assigned to the C=O group of the linker. The absorption bands at 2915 and 2870 cm-1 belonged to the C-H stretching.
40 C-H
C=O
Wavenumbers (cm )
Figure 4.9: IR spectrum of 6-CDOAc/TDI. - 81 -
The benzoylated polymers (2-CDOBz/TDI) still bore a sharp carbonyl peak at 1660 cm-1 even after the polymerization reactions. The allylated diisocyanate polymers showed bands at 1637 cm-1 and they were credited to the C=C stretches of the allyl group. A band at 1657 cm-1 in the spectrum of 6-CDOAc/TDI represents stretching of the C=O group and the one at 1100 cm-1 was caused by the stretching of the C-O group.
While it was difficult to trace the presence of some useful peaks of the substituents in the IR spectra of some polymers, specific significant stretches were utilized to endorse the successful synthesis of these nanoporous polymers. In the spectrum of 2-CDOMe/HDI (Figure 4.10), the band at 2875 cm-1 represents the stretching of the C-H group while the one at 2970 cm-1 reflected the stretching of the C-H (CH3) bonds and finally the small band at 1120 cm-1 was attributed to the isocyanate C-O bond.
C =O
W aven u m b ers (cm )
Figure 4.10: IR spectrum of 2-CDOMe/HDI.
As illustrated in the IR spectra of these compounds, the diisocyanate peak completely disappeared for all the CD polymers. Therefore, it can be concluded that the syntheses of the polymers was achieved successfully. Table 4.4 outlines the functional groups attached to the cyclodextrin as well as the yields obtained for each of the diisocyanate polymers.
Table 4.4: Table revealing the yields and linkers used for the different monofunctionalized diisocyanate CD polymers. CD polymer
R Group in CDR
Yields (%)
CDHDI
2-CDOBz/HDI
-COPh
6-CDOAc/HDI
-COCH3
2-CDOMe/HDI
2-CDOAllyl/HDI
-CH2CHCH2
6-CDOAm/HDI
-NHCH2CH2NH2
CDTDI
2-CDOBz/TDI
6-CDOAc/TDI
2-CDOMe/TDI
2-CDOAllyl/TDI
6-CDOAm/TDI
*CDR: Monofunctionalized CD
When the clear solution of the CD derivatives and the diisocyanate linkers was heated up to 70 oC for a long period of time (24 hours), white solid products were
obtained with 89 to 100% yields after the removal of DMF and overnight high vacuum drying. All the monofunctionalized polymers obtained were insoluble in water as well as other organic solvents (e.g. DMSO and DMF).
4.3.2 Synthesis and characterization of the ADP and EPC CD polymers The monofunctionalized ADP polymers were prepared by first deprotonating the C-2 secondary hydroxyl groups of the monofunctionalized CDs, followed by the addition of excess adipoyl dichloride. It may be necessary to mention that, since the β-CD was monofunctionalized (not per-functionalized), not all the OHs were substituted during monofunctionalization reactions. The hard, amorphous polymeric material formed was insoluble in water. It was obtained in quantitative yields after washing several times with acetone to remove residual DMF. This was followed by an overnight drying of the polymer under vacuum. IR spectroscopy was very useful in monitoring the vibrational changes during the course of the reaction. 100
Transmittance(%)
Figure 4.11: IR spectra of (a) 6-CDOAc/ADP and (b) 6-CDOAm/ADP.
The spectra shown in Figure 4.11 displays comparison between the IR spectrum of 6-CDOAc/ADP (a) and 6-CDOAm/ADP (b). In the spectrum of 6-CDOAc/ADP, the band for C=O occurred at 1765 cm-1, that for O-H appeared at 3500 cm-1 and that for C-O appeared at 1075 cm-1. For the polymer (6-CDOAm/ADP), notable peaks observed were found at 3450 cm-1, 2910 cm-1, 1740 cm-1 and 1100 cm-1 and these were interpreted as O-H, C-H, C=O, and C-O, respectively. While all the polymers indicated similar basic plots, reduction in the O-H peaks at about 3450 cm-1 and the appearance of the C=O bands at around 1660 cm-1 confirmed successful formation of the ADP polymers.
Finally, the addition of excess epichlorohydrin in the CD derivative solution in alkaline conditions yielded insoluble polymers. The difference between the IR spectra of the monofunctionalized CDs and the polymers suggest that polymerization has indeed occurred. The IR spectra also showed that the O-H peaks at about 3390 cm-1 were reduced significantly after polymerization reactions. Meanwhile, the similarities (appearance of O-H, C-H and C-O stretching) between the spectra of the monofunctionalized CDs and those of the polymers indicate that the basic structural units are preserved in the EPC polymers.
Transmitance (%)
N -C
C -H 10
C -O
Figure 4.12: IR spectrum of 6-CDOAm/EPC.
The spectrum for 6-CDOAm/EPC (Figure 4.12) showed an absorption band at 1750 cm-1 which was described as the carbonyl group of the polymer. The spectrum showed typical C-O stretching at 1050 cm-1 and C-N stretching at 1400 cm-1. All the other polymers were basically characterized using the same approach. The functional groups attached to the cyclodextrin and the yields obtained for each of the ADP and APC polymers are listed in Table 4.5.
Table 4.5: Table revealing the yields of the monofunctionalized ADP and EPC CD polymers. Yields
CD polymer
CD/ADP
2-CDOBz/ADP
6-CDOAc/ADP
2-CDOMe/ADP
2-CDOAllyl/ADP
6-CDOAm/ADP
CD/EPC
2-CDOBz/EPC
6-CDOAc/EPC
2-CDOMe/EPC
2-CDOAllyl/EPC
6-CDOAm/EPC
The EPC polymers were obtained at yields lower (55 to 65%) than those of the hard-amorphous ADP polymers (60 to 75 %). All EPC polymers were sticky and adhesive. This caused difficulties in handling them during work up procedures and were thus obtained at lower yields. As shown in Table 4.5, 2-CDOBz/ADP was obtained with the highest yield (75%) whereas CD/EPC was produced at very low yield (55%). While the average yield for the ADP polymers was 70%, the one for EPC polymers was found to be 60%.
In an attempt to study the thermal properties of the polymers TGA and DSC analysis of the polymers were carried out. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) represent first choice analytical tools for accurate thermal characterization of the solid state behaviour of the CD polymers in terms of water release energies.14 In addition to these well known thermoanalytical techniques used for studying the thermal properties of these starch based compounds, the following techniques are also gaining increasing importance:
(DTA),
Thermogravimetric-mass
spectroscopy (TG/MS), TG/DTA-MS and XRD.
All these instruments allow for the determination of mass and heat flow changes simultaneously with the structural identification of sample and/or decomposition products. The TGA and DSC are however considered very reliable and relatively fast methods for studying the thermal stability of CD polymers.15
4.4.1 Thermogravimetric analysis
As highlighted earlier the TGA experiments were performed by a Perkin Elmer instrument within a wide temperature range (50-800 oC). Typically, the sample was suspended in a pan of low mass and placed in the instrument's furnace. The pan is made out of an inert material and the sample is evenly distributed in the pan to facilitate the removal of gases that are evolved. The results are not recorded as an absolute mass loss/gain but rather as a percentage mass change. All the experiments were carried out in the same heating rate (10 o
C/min) in an inert atmosphere (under nitrogen gas).
The thermal behaviour of the monofunctionalized CD polymers showed very similar general features when studied with TGA. Differences could only be found in the water content, onset temperatures and mass loss values at given temperatures. Thermoanalytical profiles of these compounds were divided into four different regions suggesting a four step process. These were interpreted as follows:
The first step, which occurred from ambient temperature to about 250 °C, can be interpreted as loss of water.
(ii)
The second (300 oC) and third (410-500 oC) weight loss steps account for most of the weight loss and are associated with the formation of a residue of the CD polymer.
(iii)
The fourth step, which occurred at temperatures over 500°C, can be related to a relatively slow degradation of the residue.
Figure 4.13a, 4.13b and 4.13c show TGA curves representing the changes of weight as a function of temperature of a standard polymer, a HDI-linked polymer (2-CDOBz/HDI), a TDI-linker polymer (2-CDOBz/TDI), an ADP-linked polymer (2CDOBz/ADP) as well as an EPC-linked polymer (2-CDOBz/EPC). The figures also explain the different weight loss steps observed.
120 Water loss
Weight (%)
Thermal degradation
Temperature (oC)
Figure 4.13a: TGA curve of a standard polymer (CD/HDI polymer).17
Loss of water
T e m p e ra tu re ( C )
Figure 4.13b: TGA curve of a monofunctionalized CD polymer (2CDOBz/HDI polymer).
Figure 4.13c: TGA curves of: (a) 2-CDOBz/ADP and (b) 2-CDOBz/EPC. Whist most of the polymers had similar profiles, the four weight loss steps were not essentially observed in the TGA curves of some of the nanoporous polymers. Some polymers had different onset temperatures of each weight loss step and the TGA profiles were therefore not entirely the same, although the basic graphs were identical. Table 4.6 shows the temperature ranges and onset temperatures of different weight loss steps of the polymers which had profiles different from those of most of the functionalized polymers.
Table 4.6: 1st, 2nd, 3rd and 4th % weight loss steps in the TGA curves of some monofunctionalized polymers. CD polymer
1st weight loss (oC)
2nd weight loss (oC)
CD/HDI
3rd weight loss 4th loss weight (oC) (oC)
As indicated in Table 4.6, the third weight loss step was not observed in the TGA curve of 6-CDOAc/TDI and 2-CDOMe/TDI. It was also difficult to ascertain from the graph degradation temperature of 6-CDOAc/ADP. With the exception of 2CDOMe/HDI, which starts degrading at 350 oC, all the polymers start degrading at around 500 oC. The TGA curves of other selected polymers are outlined in
Appendix C.
This is one of the most significant thermal analysis techniques in monitoring the thermoanalytical events of CD polymers. The difference in temperature is measured between the sample and a reference material which are both subjected
programme.16
monofunctionalized CD polymers were performed with a Mettler Toledo DSC 822e Analyzer. The heat flows and temperatures associated with chemical transitions of the polymers were measured.
The samples were heated at a
constant rate of 10°C/min in a DSC pan and the average mass of each sample was 15 mg.
DSC thermal events are usually detected by deviations from the baseline. Since the thermal conductivity of the reference material and the sample are different, it is mostly difficult to determine the baseline. The DSC curve is primarily characterized by the shape of the peak, size and temperature. If an endothermic event takes place in the sample, the sample temperature will lag behind that of the reference; the profile will be curved downwards. However, if exothermic events are recorded it curves upwards.
Generally, the DSC curves of the polymers investigated in this study showed two characteristic endothermic peaks; one at about 95 oC corresponding to the boiling point of water and the other small endotherm at approximately 250 oC corresponding to the melting point of the polymers. Degradation of the polymer occurred at temperatures above 300
Figure 4.14a and 4.14b shows
comparison between a DSC curve of the standard polymer (CD/HDI) and that of 2-CDOBz/HDI polymer. The basic profile of the monofunctionalized CD polymer compares to a large extent to that of the standard polymer. This was a common observation in the DSC curves of the majority of the monofunctionalized CD polymers, with the exceptions noted later in this section.
ex o mW 15
Endothermic peak (EP) 1 0
Start of degradation
Time (min)
Figure 4.14a: A DSC curve of a standard polymer (CD/HDI polymer).
Figure 4.14b: A DSC curve of a monofunctionalized polymer (2CDOBz/HDI). - 94 -
EP 3 (360 oC)
Figure 4.15: A DSC curve of 6-CDOAm/HDI polymer.
Start of degradation EP 2 EP 1
Figure 4.16: A DSC curve of 2-CDOMe/TDI polymer.
Whilst the DSC curves for most monofunctionalized CD polymers are analogous to those of the standard polymers, there were a few curves which had insignificant differences in shape and in the appearance of endothermic peaks as well as degradation steps. The curve of 6-CDOAm/HDI (Figure 4.15) showed three different peaks at different regions: 100 oC, 160 oC and at 260 oC. With the exception of a broad peak in the melting point region for 2-CDOMe/TDI, the curve for this methylated CD polymer (shown in Figure 4.16) displays a similar profile to that of 6-CDOAm/HDI. Whereas the degradation of 6-CDOAm/TDI occurred at the normal temperature (above 300 oC), loss of moisture could be detected at 70 oC. There is also no endotherm at 250 oC in the curve of this compound, thus its melting temperature could not be ascertained.
The DSC profiles of 6-CDOAc/HDI and 6-CDOAc/TDI were both similar to that of 6-CDOAm/TDI explained above. The loss of water in the DSC curve of 2-CDOMe occurred at 90 oC and the peak at 250 oC representing the melting point was noted. Another unusual observation was a small peak appearing at 60 oC and 70 o
C for 2-CDOAllyl/TDI and 2-CDOBz/EPC, respectively. Degradation of the
residue of these two compounds was however observed in the normal place (above 300 oC). The DSC curves for other polymers are outlined in Appendix B.
With the minor exceptions noted in the discussion above, the TGA and DSC plots reveal that the monofunctionalized CD polymers have similar thermal stabilities compares to their unsubstituted counterparts. Therefore, it can be concluded that the introduction of the functional groups in the backbone of the CD macrocyle did not affect the thermal stability of the polymers. Alike their unfunctionalized
polymers, the monofunctionalized CD polymers are stable over an extensive range of temperatures (100 oC – 400 oC).
4.5.1 Introduction Since all the nanoporous polymers synthesized were insoluble in water, they render a very important feature in the removal of organic pollutants from water. They have been successfully investigated for their abilities to absorb high priority organic contaminants (p-nitrophenol and pentachlorophenol) from water. The insoluble CD polymers were deliberately placed in an aqueous solution containing known concentrations of the model organic pollutant. The results obtained from UV-Visible Spectroscopy and GC-MS analysis are discussed individually below.
p-Nitrophenol (PNP) was chosen as a model pollutant because it is highly soluble in water and is one of the priority pollutants that can be easily monitored by UVvisible spectroscopy. PNP is also a potential skin irritant, is corrosive to the eyes and has a relatively high acute toxicity by the oral route.17 The UV absorbance of the PNP water samples was measured before and after treatment with the CD polymers. The UV-absorbance of the PNP water samples was measured at 318 nm (wavelength of maximum UV-absorption).
Typically, 300mg of each monofunctionalized CD polymers were weighed and placed in a 250mL Erlenmeyer flask. To the flask, 200mL of the PNP standard
sample (10 mg/L) were carefully added and sealed with a rubber stopper. The contents of the flask were shaken using a mechanical stirrer at a constant rate for 30 minutes and thereafter filtered-off using Whatman-5 ashless filter paper.
While the polymers were in solution it was observed that they gradually assumed the yellow colour of the organic pollutant. The UV absorbance of the filtrate was then measured using a CARY 50 UV Spectrophotometer. Finally, the calibration curve was plotted and used to determine the residual filtrate concentration of each sample from which the amount of the pollutant absorbed by the polymer was determined. The absorption efficiency was determined using the equation Co − C × 100% where Co and C refer to the initial feed (i.e. before absorption) and Co
final (i.e. after absorption) concentrations, respectively.
4.5.2.1 Absorption capabilities of the diisocyanate polymers
From the absorption efficiency values, it has been established that different monofunctionalized CD polymers exhibit different affinities for this organic pollutant. The highest absorption efficiencies for PNP were obtained with 2CDOBz/HDI and 2-CDOBz/TDI polymers and are 69% and 70%, respectively (Table 4.7a and 4.7b). The methylated polymers (2-CDOMe/HDI and 2CDOMe/TDI) have the lowest efficiencies (50 and 51%, respectively). The average absorption efficiencies of all the monofunctionalized HDI and TDI CD polymers were determined by calculating their mean and are 60% and 55% respectively.
Table 4.7a: Results obtained after treating 10 mg/L PNP water samples with monofunctionalized HDI-linked β-CD polymers. Polymer type
Concentration after
Absorption efficiency
absorption (C) /mg/L
Co − C × 100% Co
*Concentration before absorption (Co): 10mg/L; λabs (PNP): 318nm; Mass of polymer: 300mg
Table 4.7b: Results obtained after treating 10 mg/L PNP water samples with monofunctionalized TDI-linked β-CD polymers. Polymer type
*Concentration before absorption (Co): 10 mg/L; λabs (PNP): 318 nm; Mass of polymer: 300 mg
From the comparison of these values with those of the standard polymers (58% for
CD/TDI),
monofunctionalized CD polymers are capable of absorbing the organic guest molecule (PNP) from water samples at mg/L levels, in a manner which is comparable to the absorption of the standard polymers.
4.5.2.2 Absorption capabilities of the ADP and EPC polymers
The absorption experiments for the ADP and EPC polymers were carried out under similar conditions using the same procedures used for the diisocyanate monofunctionalized polymers. Among these polymers, the 2-CDOBz/ADP polymer gave the highest absorption percentage (77%) while 2-CDOBz/EPC and 6-CDAm/EPC polymers absorbed 70% each. The differences in the absorption efficiencies are considerably significant and all these values are higher than those of the standard polymers (unfunctionalized polymers) which are 67% and 70% for CD/ADP and CD/EPC, respectively. The lowest absorption efficiencies were obtained with 2-CDOMe/ADP and 2-CDOMe/EPC and both had absorption efficiencies of 50%. Table 4.8 shows the absorption efficiency results of all the ADP and EPC-linked CD polymers investigated in this study.
Table 4.8: Results obtained after treating 10 mg/L PNP water samples with monofunctionalized ADP-linked and EPC-linked β-CD polymers. Polymer type
*Concentration before absorption (Co): 10 mg/L; λabs (PNP): 318 nm; Mass of polymer: 300 mg; Volume of PNP used: 200 mL
Generally, the EPC and ADP polymers exhibit improved absorption efficiencies at such concentration levels (10mg/L) compared to the diisocyanate polymers and their absorption efficiencies are generally better compared to their standard polymers at such high concentrations.
In a parallel study, samples of a much lower concentration were prepared by spiking deionized water with known concentrations of pentachlorophenol (PCP). The PCP was selected for this study because it is toxic and is currently one of the priority organic contaminants that are a major concern for environmental bodies. Furthermore, It is readily available in our laboratory and has been previously used in a related study in our research group. All the PCP water samples for this compound were prepared at 100 µg/L concentrations. Before any analysis of trace compounds could be carried out, pre-concentration of the samples was performed using an SPE. This step was crucial because of the low concentration levels of this organic pollutant in the water samples. As highlighted earlier the preconcentation procedure consisted of the following four steps: washing, conditioning, sample loading, and finally elution.
The method used for the preconcentation was modified from Method 525.2 of the Environmental Protection Agency (EPA), which is used for the determination of a wide variety of semi-volatile organics including PAHs, pesticides and PCBs in drinking water. Our GC/MS demonstrated a very low detection limit, which made it particularly suitable for this analysis. The detection limit was determined by preparing a series of the standard samples under dilution and injecting them into the GC/MS column. The instrument could detect compounds up to 10ng/L. Such a low detection limit was very important in this study because the principal aim of this study was to investigate the performance of the polymers at such low concentrations (µg/L levels) as they occur in natural waters. . - 102 -
4.5.3.2 Absorption studies of diisocyanate polymers
A summary of the absorption efficiencies of different monofunctionalized diisocyanate polymers on a 100 µg/L sample is outlined in Table 4.9a and 4.9b. The polymers demonstrate absorption efficiencies ranging between 70-100%. These values are however comparable to the absorption efficiencies of the standard CD polymers. The benzoylated and allylated polymers showed the highest absorption efficiency of 100%.
Table 4.9a: Results obtained after treating 100 µg/L PCP water samples with monofunctionalized HDI-linked β-CD polymers. Concentration after
absorption (C) /µg/L
Polymer type
*ND: Not detected, m/z (PCP) = 266, TR (PCP) = 11.995; Concentration before absorption (Co): 100 µg/L; Mass of the polymer used: 500 mg; Volume of sample used: 500 mL
Table 4.9b: Results obtained after treating 100 µg/L PCP water samples with monofunctionalized TDI-linked β-CD polymers. Polymer type
While 6-CDOAm/TDI has the lowest absorption efficiency (57%), the average absorption efficiency of the HDI-linked polymers is 87% and that of the TDI-linked polymers is 84%. The chromatographs (Figure 4.17 and 4.18) show PCP peaks before and after passing the water samples through the 2-CDOBz/TDI and 2CDOBz/HDI polymers, respectively. It can be observed from these plots that the PCP peak is completely removed or greatly reduced after passing the PCP sample through the polymers.
kCounts 17.5
(a) 100 µg/L PCP sample before treatment with polymer.
0.0 kCounts 17.5
(b) 100 µg/L PCP sample after treatment with polymer.
11.944 min
Figure 4.17: GC/MS chromatographs showing treatment of a 100 µg/L sample with a 2-CDOBz/TDI polymer.
kCounts
0.0 kCounts 20
(b) 100 µg/L PCP sample after treatment with polymer. 15
11.944 min 10
Figure 4.18: GC/MS chromatographs showing treatment of a 100 µg/L sample with a 2-CDOBz/HDI polymer.
4.5.3.3 Absorption studies of ADP and EPC polymers
The absorption efficiency of the monofunctionalized ADP and EPC polymers were similar. The highest absorption efficiency was observed with the 2CDOBz/ADP and 6-CDOAm/ADP, which showed 89% absorption and the lowest absorption was observed with 2-CDOAllyl/EPC (69%). These are outlined in
Table 4.10.
Table 4.10: Results obtained after treating 100 µg/L PCP water samples with monofunctionalized ADP and EPC-linked β-CD polymers. Polymer type
absorption (C) /µg/L CD/ADP
The monofunctionalized polymers are therefore very efficient in quenching phenolic compounds (PNP and PCP) at very low concentrations in a manner that is comparable to their free counterparts (standard polymers). However, the TDI polymers are generally better in the absorption of PCP compared to the HDI polymers. The same observation was noted even in the standard polymers.18 This suggests that the introduction of the various functional groups to the backbone of the polymers does not alter their absorption capabilities. However, it must be stressed that the monofunctionalized polymers are stable over a more extensive temperature range (100oC – 400oC).
Another important observation was that the 2-substituted CD polymers are generally better in the absorption of both organic pollutants investigated, compared to the 6-subtituted polymers. This observation can be supported by the fact that the readily substituted functional groups at C-6 are free to rotate thus effectively blocking the opening of the primary side.
An inferior absorption
efficiency was observed for PNP at higher concentration (i.e. mg/L levels). This confirms an earlier study's assertion that the CD polymers are only effective at low concentrations (i.e. µg/L levels).18 At such high concentrations (mg/L) it is likely that the polymers get easily saturated and thus lose their effectiveness.
However, due to their recyclability efficiency, these polymers could still be more effective even at higher concentrations. In recyclability, the polymer is washed with ethanol to remove absorbed organic contaminants in the CD.18 Recyclability is vital when evaluating the application of this technology because it allows for cost-effectiveness. This is still subject to further investigation.
1. Dienst E. (1994), PhD. Thesis: Water insoluble cyclodextrin based host molecules, University of Twente (NL). 2. Schneider H.J., Hacket F., Rudiger V., Chem. Rev. 98 1998 1755. 3. Gao X.M., Tong L.H., Inoue Y., Tai A., Synth. Commun. 25 1995 703. 4. Atwood
Lenh
Chemistry, Eds,: Vol 3, Cyclodextrins; Szejtli J., Osa T., Eds;, Pergamon; Oxford, U.K. 5. Zhong N., Byun H.S., Bittman R., Tetrahedron Lett. 39 1998 2919. 6. Melton L.D., Slessor K.N., Carbohydr. Res. 18 1971 29. 7. Breslow R., Pure Appl. Chem. 66 1994 1573. 8. Byun H.S., Zhong N., Bittman R., Organic Synthesis 77 1999 225. 9. Kurozumi M., Nambu N., Nagai T., Chem. Pharm. Bull. 23 1975 3065. 10. Aoyagi T., Nakamura A., Ikeda H., Ikeda T., Mihara H., Ueno A., Anal. Chem. 69 1997 659. 11. Sutyagin A.A., Glazyrin A.E., Kurochkina G.I., Grachev M.K., Nifant'ev E.E. Russian Journal of General Chemistry 72 2002147. 12. Hanessian S., Benalil A., Laferriere C., J. Org. Chem. 60 1995 4786. 13. Lee K.P., Choi S.H., Ryu E.N., Ryoo, Park J.H., Kim Y.S., Hyun M.H., Analytical Sciences 18 2002 31. 14. Giordano F., Novak C., Moyano J.R., Thermochimica Acta 380 2001 123. 15. Liu Y., Zhao Y.L., Chen Y., Ding F., Chen G.S., Bioconjugate Chem. 15
2004 1236. 16. Bettinetti G., Gazzaniga A., Giordano F., Sangalli M.E., Eur. J. Pharm. Biopharm. 40 1994 209. 17. US Environmental Protection Agency, Prevention, pesticides and toxic substance (7508W), EPA-738-F-97-016, January 1998. - 109 -
18. Mhlanga S.D. (2005), M. Tech dissertation, University of Johannesburg.
CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS
The primary objectives of the study were to synthesize and characterize monofunctionalized cyclodextrin polymers and test their abilities in the removal of persistent organic pollutants from water. Based on the initial aims of the project it can be concluded that this project was a success. The following conclusions and recommendations can therefore be made:
Practical and simple procedures for monofunctionalization of the hydroxyl groups of the CDs have been demonstrated in this study. A wide variety of monofunctionalized cyclodextrins have been successfully prepared in relatively high yields using straightforward work-up procedures. Sulfonation, methylation, allylation, benzoylation, acetylation and amination reactions were all carried out using efficient modification strategies. All the novel monosubstituted cyclodextrins obtained were satisfactorily characterized with IR, 1H NMR and 13C NMR spectroscopic techniques.
There are basically two methods adopted during the synthesis of these CD derivatives. The first approach involved the conversion of the CD moiety to an intermediary
monotosylate,
corresponding functionality. The second method entailed the deprotonation of the more acidic hydroxyl groups with a strong base followed by the introduction of the desired functional groups. These general methods were also utilized in synthesizing other novel important derivatives such as higher acyl derivatives.
The remaining hydroxyl groups of each of the CD derivatives were successfully treated with effective difunctional cross-linkers. The methods used for the polymerization reactions successfully produced highly crosslinked insoluble nanoporous polymers. This was achieved by reacting the monofunctionalized CDs and a corresponding linker and varying the reaction conditions to yield polymers with different physical properties and absorption abilities.
Particularly,
(TDI),
hexamethylene
diisocyanate (HDI), adipoyl dichloride (ADP) and epichlorohydrin (EPC) linked β-cyclodextrin polymers were successfully prepared in superior yields. The polymers were mainly characterized by IR spectroscopy due to their insoluble nature. ƒ
To test if the polymers could absorb organic pollutants from water, water samples with low concentrations (100 µg/L and 10mg/L) of organic contaminants (pentachlorophenol and p-nitrophenol, respectively) were prepared. The PCP samples were first pre-concentrated by solid phase extraction and successfully analyzed using Gas Chromatography-Mass Spectrometry (GC/MS) while the PNP samples were analyzed using UVVisible spectroscopy. The nanoporous polymers that were prepared have shown good absorption abilities, which compared favourably to their unfunctionalized counterparts.
As evidenced by the TGA and DSC studies, these monofunctionalized polymers are stable over a wide range of temperature (100 – 400°C) and have basically similar thermal behaviour with the standard polymers.
5.2 Recommendations ƒ
It is evident however that the scope of this project has been focussing on the monofunctionalization of the β-CDs. It can be recommended that more work be performed on the other types of these starch derivatives (α- and γ-CDs) in a quest to mitigate the growing need for the development of cheaper methods for the synthesis of modified CDs. Functionalization of the whole set of the hydroxyl groups (per-functionalization) may also have a greater effects in varying the absorption properties of these compounds.
Solid state NMR and other solid state characterization techniques are required for full characterization of these insoluble polymeric compounds. Further characterization of the CD polymers using circular dichroism is necessary for the study of the molecular dimensions of the polymers.
A disposal system for dumping the polymers with the organic pollutants needs to be developed or developing a method of recovering the pollutants. This can be more useful when the polymers are employed at an industrial scale.
It is evident from this research that the mono-functionalization of the β-cyclodextrins can provide a useful framework for tailor-making the nanosponge polymers to meet specific industry needs. The outcomes of this study are expected to create a foundation for the use of cyclodextrin polymers in water purification, in the near future. Further work pursued in our laboratories involves the synthesis of polyurethanes; whereby carbon-nanotubes (basically concentric sheets of hexagon carbons)
resulting
polyurethanes are expected to exhibit features for absorbing organic pollutants from water systems at very low concentrations while maintaining a higher level of thermal stability.
Selected 1H NMR, 13C NMR and IR spectra of cyclodextrin derivatives.
H NMR spectrum for β-CD (1)
C NMR spectrum for β-CD (1)
H NMR spectrum for Ts2O (2)
H NMR spectrum for 6-CDOTs (3)
C NMR spectrum for 6-CDOTs (3)
C NMR spectrum for 2-CDOBz (6)
H NMR spectrum for 2-CDOMe (7)
H NMR spectrum for 6-CDOAm (4)
H NMR spectrum for 6-CDOAc (5)
C NMR spectrum for 6-CDOAc (5)
Transmittance
SO2symmt. C-H
C-H SO2assym.
Wavenumbers/cm
Figure A1: IR spectrum of the β-CDOTs
Wavenumbers (cm ) Figure A2: IR spectra of (a) 2-CDOBz/ADP and (b) 2-CDOBz/EPC.
APPENDIX B ________________________________________________________________ Selected TGA and DSC curves
Weigth (%)
Tem perature ( C)
Figure B1: TGA thermogram of the 2-CDOAllyl/HDI polymer
Temperature ( C) Figure B2: TGA thermogram of 2-CDOAm/HDI polymer
Temperature ( C) Figure B3: TGA thermogram of the 6-CDOAc/TDI polymer 100
Temperature ( C)
Figure B4: TGA thermogram of the 2-CDOMe/TDI polymer
Figure B5: A DSC curve of 6-CDOAm/TDI polymer
Figure B6: A DSC curve of 6-CDOAc/HDI polymer
Figure B7: A DSC curve of 6-CDOAc/TDI polymer
Figure B8: A DSC curve of 2-CDOMe/HDI polymer
Figure B9: A DSC curve of 2-CDOAllyl/APD polymer
Figure B10: A DSC curve of 2-CDOBz/EPC polymer
APPENDIX C ______________________________________________________________ C1: Selected chromatograms of PCP Figure C1 to C4 shows the spectrum as well as selected chromatographs of the PCP.
The plots shown are only for the polymers that demonstrated 100%
absorption efficiencies.
kC ounts
I ons: 266.0 Merged 100m gl.pc p.s t d.s ab.25.5. sm s 2000 CEN TR OID RAW 1A
Spec trum 1A BP 266 (125595=100% ) 100mg l.pc p.s t d.s ab.25.5.s m s 100%
m inutes
11.977 m in. Sc an: 766 C hannel: M erged Ion: 311 us RI C: 787608 266 125595
268 102879 75%
0% 240
Figure C1: Chromatogram and mass spectrum of PCP.
m /z
(a) 100 µg/L PCP sample before treatment with polymer. 5.0
0.0 kCounts
(b) 100 µg/L PCP sample after treatment with polymer. 5.0
Figure C2: GC/MS chromatographs showing treatment of a 100 µg/L sample with a 2-CDOAllyl/TDI polymer.
Figure C3: GC/MS chromatographs showing treatment of a 100 µg/L sample with a 6-CDOAm/ADP polymer.
(a) 100 µg/L PCP sample before treatment with polymer. 10.0
Figure C4: GC/MS chromatographs showing treatment of a 100 µg/L sample with a 2-CDOAc/HDI polymer.
APPENDIX D
Types of pollutants and their effects
Table D1: Types of water pollutants and some of their effects.1 Pollutant
Anthropogenic Sources
General Effect
Effect on Biota
Effect on Water Supplies
Steel plants Cooling towers Power generation
Decrease in concentration of dissolved dioxygen Increase in metabolism of living organisms
Possible reduction in the ability to breed and growth rate
Quarrying Paper mills Run-off from roads
Soil erosion Storms Floods
An increase in turbidity and therefore a reduction in light penetration Discolours water Covering/ blanketing bottom after settling
Reduction in ability of plants to photosynthesize Clogging gills of fish Blanketing of bottom-living plants and animals
Blocks filtering systems Need to treat water to remove solids
Detergents Oils
Formation of foams which could prevent oxygen and carbon dioxide exchange Changes surface tension of water
Reduction in dissolved dioxygen Life cycle of some insects affected
Interfere with treatment process May need extra treatment if particularly stable foams formed
Biodegradable wastes
Domestic sewage Animal wastes from farms Food processing companies
Run-off and seepage through the soil
Oxygen demand increases Provide food for organisms lower in the food chain
Can be useful to organisms as source of food If too much is present can reduce dioxygen to dangerous/ fatal levels
Will need extra treatment
Nitrates, phosphates and other possible plant nutrients
Detergents Fertilizers Tanneries Intensive animal husbandry Ammoniacontaining industrial wastes
Excessive plant growth
Heavy demand on dissolved dioxygen
Inorganic chemicals (e.g. acids, alkalis, salts)
Steel, chemicals and textile industries Coal and salt mining
Naturally acid or alkaline rocks
Raise or lower the pH
Plants and animals can only tolerate a narrow range of pH
Corrosion of equipment and pipes Silting
Toxic chemicals (e.g. heavy metals like mercury and lead, phenols, PCBs)
Detergents Pesticides Tanneries Pharmaceuticals Oil refineries
Poison living organisms
Can cause death in animals and humans
Water cannot be used until levels of toxic materials are at acceptable levels May require extensive extra treatment
Pathogenic bacteria and viruses
Raw sewage
Bacteria can cause diseases Action of viruses uncertain
Can prove fatal
Table D2: Some environmental effects of some selected herbicides.1 Herbicide
Propanil
Moderately toxic
Moderate to highly toxic
Moderate persistence
Chloroprophan
Moderate persistence Strongly adsorbed on organic matter but not on soil
Leached out of soil with low organic content
Trifluralin
Very highly toxic (and to other aquatic species)
Low solubility Not readily leached
Slightly toxic
Moderate persistence Strongly adsorbed
Although soluble is not readily leached
2,4-D
Slightly to moderately toxic
Slightly to highly toxic
Low persistence
Has been detected in groundwater
Sulfometuronmethyl
Practically nontoxic
Slightly toxic to adult fish
Low persistence Not strongly adsorbed
Slightly soluble therefore potential pollutant
Highly persistent Not strongly adsorbed
Moderately mobile in water Potential pollutant
Floumeturon
Highly persistent Poorly adsorbed
Moderately soluble therefore potential pollutant
Highly persistent Strongly adsorbed
Very soluble in water but soil adsorption prevents water contamination
Table D3: Some environmental effects of some selected insecticides.1 Insecticides
Highly toxic
Extremely toxic
Readily adsorbed by soils Moderate persistence
Very low solubility therefore no leaching Not found in groundwater
Slightly to very toxic according to species
Not readily adsorbed by soil. Low persistence
Soluble and undergoes chemical reaction in water. Danger of leaching
Parathion
Strongly adsorbed on soil Moderate persistence
Undetectable in water within one week due to adsorption on sediments
Diazinon
Slight solubility therefore pollutes groundwater. pH affects rate of decomposition
Carbaryl
Detected in run-off and groundwater. Stability pH detected
Diflubenzuron
Low soil mobility. Low persistence
Fenoxycarb
Strongly adsorbed on soil Low persistence
Not leached. The higher the pH the faster the decomposition
Hydramethylon
Strongly adsorbed by soil. Low soil mobility. Low soil persistence
Slightly soluble. Not very water mobile. Readily hydrolysed at high pH.
1. Wright J. (2003), Environmental chemistry, Routledge introductions to environmental series, London.
Report "chapter 1"
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Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents
J. Gardecki, M. L. Horng, A. Papazyan, Mark Maroncelli
Materials Research Institute (MRI)
The dynamics of solvation of the probe solute coumarin 153 has been measured with ~100 fs time resolution using the fluorescence upconversion technique. A wide variety of solvents, including polar aprotic solvents, hydrogen bonding solvents, and non-dipolar solvents have been examined. For all solvents of even moderate polarity (49-01), the solvation dynamics observed follows the predictions simple models based on the solvent's bulk dielectric response. For a number of "non-dipolar" solvents such as dioxane and benzene, for which (49-02), we observe surprisingly large time-dependent shifts, which seem to reflect the solute interacting with the large quadrupole (and higher multipole) moments of the solvent molecules. These dynamics represent a solvation distinct from the dipolar solvation dynamics previously studied and they cannot be modeled in terms of any currently available theory.
Studies in Physical and Theoretical Chemistry
Dive into the research topics of 'Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents'. Together they form a unique fingerprint.
solvation Physics & Astronomy 100%
Polar Solvent Chemical Compounds 90%
Solvation Chemical Compounds 77%
Solvent Chemical Compounds 42%
Solute Chemical Compounds 21%
Multipole Moment Chemical Compounds 21%
Coumarin 153 Chemical Compounds 20%
solutes Physics & Astronomy 20%
Gardecki, J., Horng, M. L., Papazyan, A., & Maroncelli, M. (1995). Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents. Studies in Physical and Theoretical Chemistry, 83(C), 49-57. https://doi.org/10.1016/S0167-6881(06)80760-3
Gardecki, J. ; Horng, M. L. ; Papazyan, A. et al. / Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents. In: Studies in Physical and Theoretical Chemistry. 1995 ; Vol. 83, No. C. pp. 49-57.
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abstract = "The dynamics of solvation of the probe solute coumarin 153 has been measured with ~100 fs time resolution using the fluorescence upconversion technique. A wide variety of solvents, including polar aprotic solvents, hydrogen bonding solvents, and non-dipolar solvents have been examined. For all solvents of even moderate polarity (49-01), the solvation dynamics observed follows the predictions simple models based on the solvent's bulk dielectric response. For a number of "non-dipolar" solvents such as dioxane and benzene, for which (49-02), we observe surprisingly large time-dependent shifts, which seem to reflect the solute interacting with the large quadrupole (and higher multipole) moments of the solvent molecules. These dynamics represent a solvation distinct from the dipolar solvation dynamics previously studied and they cannot be modeled in terms of any currently available theory.",
author = "J. Gardecki and Horng, {M. L.} and A. Papazyan and Mark Maroncelli",
journal = "Studies in Physical and Theoretical Chemistry",
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Gardecki, J, Horng, ML, Papazyan, A & Maroncelli, M 1995, 'Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents', Studies in Physical and Theoretical Chemistry, vol. 83, no. C, pp. 49-57. https://doi.org/10.1016/S0167-6881(06)80760-3
Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents. / Gardecki, J.; Horng, M. L.; Papazyan, A. et al.
In: Studies in Physical and Theoretical Chemistry, Vol. 83, No. C, 01.01.1995, p. 49-57.
T1 - Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents
AU - Gardecki, J.
AU - Horng, M. L.
AU - Papazyan, A.
AU - Maroncelli, Mark
N2 - The dynamics of solvation of the probe solute coumarin 153 has been measured with ~100 fs time resolution using the fluorescence upconversion technique. A wide variety of solvents, including polar aprotic solvents, hydrogen bonding solvents, and non-dipolar solvents have been examined. For all solvents of even moderate polarity (49-01), the solvation dynamics observed follows the predictions simple models based on the solvent's bulk dielectric response. For a number of "non-dipolar" solvents such as dioxane and benzene, for which (49-02), we observe surprisingly large time-dependent shifts, which seem to reflect the solute interacting with the large quadrupole (and higher multipole) moments of the solvent molecules. These dynamics represent a solvation distinct from the dipolar solvation dynamics previously studied and they cannot be modeled in terms of any currently available theory.
AB - The dynamics of solvation of the probe solute coumarin 153 has been measured with ~100 fs time resolution using the fluorescence upconversion technique. A wide variety of solvents, including polar aprotic solvents, hydrogen bonding solvents, and non-dipolar solvents have been examined. For all solvents of even moderate polarity (49-01), the solvation dynamics observed follows the predictions simple models based on the solvent's bulk dielectric response. For a number of "non-dipolar" solvents such as dioxane and benzene, for which (49-02), we observe surprisingly large time-dependent shifts, which seem to reflect the solute interacting with the large quadrupole (and higher multipole) moments of the solvent molecules. These dynamics represent a solvation distinct from the dipolar solvation dynamics previously studied and they cannot be modeled in terms of any currently available theory.
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Gardecki J, Horng ML, Papazyan A, Maroncelli M. Ultrafast measurements of the dynamics of solvation in polar and non-dipolar solvents. Studies in Physical and Theoretical Chemistry. 1995 Jan 1;83(C):49-57. doi: 10.1016/S0167-6881(06)80760-3
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Language, Interpretation, and Translation: A Clarification and Reference Checklist in Service of Health Literacy and Cultural Respect
By Marin P. Allen, Robert E. Johnson, Evelyn Z. McClave, and Wilma Alvarado-Little
February 18, 2020 | Discussion Paper
"The first skill of a great translator is humbleness, to be a servant. Once you are a servant, you may be lucky to be called a master of your craft. And, you need the humbleness to understand your original, to be part of it—then also the practical humbleness to get someone who knows more than you to check your work. That collaboration is very enriching and very rewarding—a good way of ensuring you produce a decent translation."
— Marco Sonzogni, n.d.
"Translation is not a matter of words only; it is a matter of making intelligible a whole culture."
— Anthony Burgess [8]
Language, interpretation, and translation are becoming increasingly critical parts of practicing medicine across the United States. However, these areas often aren't considered before the patient is sitting in front of the clinician—and at that point, it is too late. Interpretation, translation, and regard for language need to be incorporated across the clinical workflow and deeply considered and planned for well in advance of the patient seeking care.
This manuscript describes complex problems of language, interpretation, gesture, and translation and recommends solutions. Simply providing definitions for the topics discussed does not provide an effective message for understanding the human context of language—especially in medical settings.
Recently, NAM Perspectives published "A Journey to Construct an All-Encompassing Conceptual Model of Factors Affecting Clinician Well-Being and Resilience" [7]. This constitutes an important effort to create a more holistic view of the provider. The authors of this manuscript contend that this same 360-degree model of the clinician could be matched with a 360-model of an interpreter or translator and a 360-degree model of the patient's stressors. Using these two additional representations could provide a better understanding of all factors at play.
During our careers in linguistics, communication, and interpretation, and from our work in health literacy, it has become clear to the authors that many health professionals lack a clear resource to help them navigate the multilingual reality of health care in the United States. In this manuscript, we offer linguistics, gesture, health literacy, health communication, and cross-cultural experience as lenses through which to consider cross-discipline communication. We also offer a checklist to guide providers when they do not share a common language with their patients.
Scope of Language Challenges
Providing a free flow of accurate information and a clear understanding about how to improve human health and prevent disease depends upon spoken, written, or signed words. Central to effectively sharing this knowledge is knowing how to meet people in a fair and trustworthy way while respecting the complexities and values within and among varying cultures.
A core principle underlies all communication: humans communicate symbolically. Even the languages people speak, write, or sign are, at their essence, symbols. Burke described humankind as a "symbol-using animal" whose reality has actually been "built up for us through nothing but our symbol system" [9].
The issues of language access and effective communication are much more complex and require much more attention than what occurs when people state that they need to "get someone to translate it" or "find someone who speaks some Farsi or Spanish." Communication is difficult, and communicating about often frightening and overwhelming health issues is even more complex. When a health care provider does not speak the same language as those being treated, relationships can quickly become strained, important pieces of information can be lost, and gestures or turns of phrase can be misinterpreted. These lapses in language can change the course of someone's life.
The number of languages spoken in the U.S. compounds this complexity. Historically, 39 languages had been tracked through the American Community Survey of the U.S. Census Bureau. But, in 2015 the bureau reported that more than 350 languages are spoken and signed at home in the United States. These data also included more than 150 Native American languages (such as Apache and Yupik) as well as additional information about language use in 15 metropolitan areas. In the release, Erik Vickstrom, a Census Bureau statistician, noted that "in the NY Metro area more than a third of the population speaks a language other than English at home, and close to 200 different languages are spoken." He added, "Knowing the number of languages and how many speak these languages in a particular area provides valuable information to policymakers, planners, and researchers" [22]. These data also help to give context to the increasing complexity in navigating the health care system.
The challenge and necessity of translation and interpretation in health care are illustrated in Flores' concrete 2006 New England Journal of Medicine article on language barriers and his systematic review of the impact of medical interpreter services on the quality of health care in the United States. In this perspective, Flores notes that "the provision of adequate language services results in optimal communication, patient satisfaction, outcomes, resource use, and patient safety" [13].
Flores describes, with direct quotations of the interactions, the problematic exchanges that occurred when a 12-year-old Latino boy arrived at an emergency department with his mother and met with a physician who spoke little Spanish. Since an interpreter was not available, this minor "acted as his own interpreter."
The physician misinterpreted when the mother stated that her son was dizzy, thinking the mother said that her son looked yellow. When the physician asked the boy about this, his mother responded, "You were dizzy, like pale," and the boy reported to the physician that his mother said, "Like I was paralyzed, something like that" [13].
The confused communication among the boy, his mother, and the physician presented very real safety issues and could have resulted in, for example, a missed diagnosis for juvenile diabetes. The authors encourage readers to review Flores' perspective in full. This excellent resource demonstrates the challenges of, errors in, and outcomes of, language services experienced by physicians and patients alike in the medical setting.
The significance of Flores's paper was recognized in a contemporaneous editorial in Oncology Nursing Forum by Caroll-Johnson, "Lost in Translation" [10]. Carroll-Johnson concluded that "As the world shrinks and our communities become more diverse, we must be prepared to address these dilemmas with real solutions and not rely on middlemen, women, or children lacking in understanding to do our work for us."
Reporting on an additional medical setting, outpatient practice, Jacobs and colleagues cite and describe the medical and financial impact of one catastrophic missed interpretation [25]:
On his initial medical history, a Spanish-speaking boy aged 18 years, of Cuban descent, presented with abnormal mental status complaining of "intoxicado." An untrained interpreter understood this to mean that the boy was intoxicated – though in the Cuban dialect, the boy was actually saying that he was "nauseated." He received care for a drug overdose attributed to substance abuse but developed paraplegia, subsequently found to be due to a ruptured intracranial aneurysm. The case led to a malpractice lawsuit with a $71 million award to the plaintiff. [26,27]
The authors also review current law, regulation, and policy and the comparative costs of interpreter services and systems in outpatient practice.
As our nation becomes more multicultural, the challenges will become only more complex. The time to address language, interpretation, and translation as critical parts of the health system is now.
Interpretation and Translation: Defining Terms
People often believe that interpretation involves spoken language and that translation involves written language. While these definitions may differentiate the two terms in a general way, there is actually a great deal more to each concept, as we describe below.
Interpretation involves two essential characteristics.
First, it involves the rendering of live utterances in one language to live utterances in another language. The "source language" is the language of the speaker (or signer). The "target language" is the language of the receiver of the interpretation. Interpreting necessarily involves one of three possible dyads: (a) spoken source language and spoken target language, (b) spoken source language and signed target language, or (c) signed source language and signed target language.
Second, interpretation, being a live act, necessarily involves an immediacy not characteristic of translation. That is, the interpreter has to process a piece of speech and render it—either simultaneously or consecutively—into the other language, without the opportunity to consider alternative renderings.
In an example of simultaneous interpretation, the patient speaks (or signs) in their source language, and the interpreter speaks aloud (or signs) what is being said in the target language for the health provider. The interpreter is, at the same time, comprehending the next part of the source's message.
This is complex. Different interpreters will vary in their delay between the uttered (or signed) discussion and their rendering of the message. The interpreter receives, produces, and converts at the same time. In this example, the interpreter will reverse immediately to simultaneously interpret the information from health care provider to the patient. Unlike in most health care settings, informal presentations, such as a conference, this might involve the speaker using a publicly transmitted channel and the interpreter using a private channel that can be heard only through earphones.
In interpretations between a signed language and a spoken language, simultaneous interpretation is common, because the vocal-auditory channel and the gestural-visual channel do not compete. In the health care environment, positioning of the patient, interpreter, and provider are of great importance and should be carefully planned.
Under any conditions, simultaneous interpretation presents linguistic and cognitive challenges. The results sometimes suffer from inaccuracies not found in other forms of interpretation that allow for greater time delay between the produced utterance and the rendered interpretation.
These difficulties occur not only in spoken language interpreting but during sight translation (on-the-spot translation from documents or directions provided during the visit) that are also interpreted to the patient.
In all cases, the quality of simultaneous interpretation will be improved if the interpreter has access to the text or to accompanying electronic media ahead of the actual event. In medical settings, such access may not be possible, so the pace of simultaneous interpretation may need to be slowed to ensure greater accuracy.
In an alternative form of interpretation, called consecutive interpretation, the sender produces (or signs) a short utterance (perhaps a sentence or two) and then pauses while the interpreter renders these pieces into the target language. Upon completion of the interpretation, the sender produces the next short piece of language.
Take this example passage: "I am going to explain the side effects of this medication, which include possible shortness of breath, nausea, dizziness, and anxiety. So, if you experience any of these, call me or go to the emergency room." Consecutive interpretation would create pauses that are helpful to both the patient and the interpreter. "I am going to explain the side effects of this medication [PAUSE], which include possible shortness of breath [PAUSE], nausea, dizziness, and anxiety. [PAUSE] So, if you experience any of these, call me [PAUSE] or go to the emergency room."
Consecutive interpretation can be more precise and accurate than simultaneous interpretation because it gives the interpreter more time to seek an appropriate rendering and does not involve the cognitive challenge of undertaking the two tasks of listening and rendering at one time (as in simultaneous interpreting). It can also be more time consuming because each communicator must wait for the interpretation to be completed before initiating the next "turn."
Translation involves movement between the written forms of two languages. It is important to acknowledge that there exist translations for unwritten languages [e.g., the endangered tribal language of Coeur d'Alene or to American Sign Language]. There are also translations between differing sign languages. Sometimes misunderstood, it is important to note that sign language is not universal.
More precisely, translation tends to involve movement between a recorded form of one language into a recorded—not necessarily the same form— of another language. In this sense, "recorded" could include written text, audio recordings of spoken language, or video recordings of either spoken or signed languages.
The essential characteristic of translation is that it tends not to be "live." It involves longer time spans between the source production and the rendering into the target language. The time difference provides the opportunity for consideration of alternative translations, research into previously produced translations, assistance from automatic translators by computer, and revision of the final target production. Translation differs from interpretation not because it produces different materials, but because it offers the opportunity to consider the input and output provided since the target production is "unglued" or separated in time from the source material.
As Youdelman notes, "The most qualified translators are those who write well in their native language and who have mastered punctuation, spelling and grammar. Translators know how to analyze a text and are keenly aware of the fact that translation does not mean word-for-word replacement, but that context is the bottom line for an accurate rendition of any text" [24]. The best translators understand the nuance and connotative power of both languages and understand the level of diction that is appropriate to the texts and the audiences.
Sight Translation
Sight translation is the "translation of a written document into spoken/signed language. An interpreter reads a document written in one language and simultaneously interprets it into a second language" [19].
In a health care setting, this usually occurs when a spoken language interpreter is handed a document in the moment during the interpreting assignment. Documents can have varying lengths, and there is often no opportunity for the interpreter to review them before the interpreting encounter. Although this process can be effective for documents that are short and clear, interpreters are sometimes asked to provide a sight translation for longer and more complex documents. These longer documents include such important items as consent forms, forms for advance directives, and detailed educational materials. Such forms should be translated prior to their use.
The challenges associated with sight translation include requiring the interpreter to speak and read in two languages at the same time. Ultimately, this may threaten the accuracy, clarity, and thoroughness of communication for the patient and the health care provider.
Why Skilled Interpreters are Key to Effective Health Care
It is important to point out that—while all interpreters, by definition, are bilingual—not every bilingual person can interpret. Professional interpreters undertake substantial training in both languages and in moving between them. These days, many interpreters have master's degrees, reflecting the years of practice necessary to become proficient at rendering the product of one language into another in an efficient, accurate, and meaningful way. In addition, for a limited number of languages, national certification programs are in place. However, certification is not available for all spoken languages.
Bilingual ability differs from person to person. Most bilingual individuals have differential levels of competence in their two languages, often more so if they have not formally studied both languages and learned how to translate and interpret in each of the two languages. This requires more skill than being conversationally fluent in two languages.
While it is convenient and not uncommon to use family members, friends, or passersby as interpreters, the appropriateness of this practice diminishes as the stakes of the event become greater. Whereas a person's sister might function well in assisting in the communication between persons at an informal dinner, the same sister may be seriously unqualified to function as an interpreter in a health care setting. The fact that a patient might feel more comfortable with a family member should not outweigh the need for an accurate interpretation of what the health care professional says and how the patient responds.
Moreover, untrained interpreters may balk at explanations involving bodily functions or critical injuries. Due to cultural beliefs or an age difference between a younger family member and an elder, it might be considered disrespectful for a younger person to present many types of questions to an elder. This is especially true when dealing with personal or sensitive topics.
In addition, legal issues related to privacy come into play when employing an interpreter in a health care setting. Professional health care interpreters will have learned how to discuss these issues in their training.
Finally, it may not be sufficient to have a good interpreter. In many settings, especially those involving very specialized vocabulary (such as clinical settings and research environments), interpreters may need to have special experience with fields of health care, the vocabulary used in those fields, and the indications that are under discussion.
Although appropriate and in-person interpreters may not always be readily available, the authors of this manuscript believe they are necessary for effective communication with individuals who speak a different language from their health care provider. Providers may feel that the absence of an interpreter is equivalent to the absence of effective communication, and the patient, without an interpreter, is not participating in their own health care. No one is served in this situation.
To demonstrate the high stakes of such a situation, Fadiman's classic study of cross-cultural communication in medical settings, The Spirit Catches You and You Fall Down: A Hmong Child, Her American Doctors, and the Collision of Two Cultures, provides an extended description of interactions involving a Hmong child over many years [12].
Interpretation Challenges and Signed Languages
Signed language interpreting and spoken language interpreting have almost everything in common except the channel of the signals. Signed languages, such as American Sign Language, can fully discuss any medical or scientific topic that can be discussed in English or another spoken language.
The primary differences in interpreting between a signed and a spoken language and interpreting between two spoken languages tend to be practical differences. Interpreting an English utterance into a signed language may take a bit more time than the equivalent spoken language interpretation, especially if there is a lot of technical vocabulary. Technical words may have to be spelled out if there is not a sign in the language corresponding to that concept.
In addition, when two spoken languages are involved, it is easy for the health care practitioner to notice when the interpreter's turn at speaking is finished. It is not always so easy for a hearing person with little experience in such situations to know when the interpreter is finished with their utterance if they are interpreting spoken utterances into sign language.
With a sign language interpreter, there may be a substantial delay between when the practitioner is finished speaking and when the interpreter finishes interpreting the utterance. This can lead to overlaps that hinder the quality of the communication. A certain amount of flexibility and patience may be required of the medical practitioner in order not to overlap excessively with the interpreter.
Lastly, as a clinical event involving an interpreter will almost certainly require more time than one in which the patient shares a language with the practitioner, it is advisable that practitioners adopt flexible scheduling practices to accommodate patients who require interpreters.
Earlier in this discussion, the authors of this manuscript noted the immediacy of the process in which an interpreter takes a piece of speech or sign and renders it—simultaneously or consecutively—into another language without the opportunity to consider alternative renderings. This focus applies to formal interpretation between two differing languages, but differences within the same language regarding health literacy terms should also be considered. The patient and the health professional may both speak English or Spanish or Urdu, but their comprehension may not be equivalent. The specialized medical terminology and complex concepts for describing disease or treatment processes often hamper understanding.
Further, in an interpreted consultation, there are two potential sources of misunderstanding. An interpreter may misunderstand (and misinterpret) the patient, and the doctor (or the patient) may misunderstand the interpreter. Teach-back is a very effective method for identifying trouble spots in interpretation.
Cultural Appropriateness of the Interpreter
Because interpreters are the "voice" of the person for whom they are interpreting, more should be considered than just the technical message to be transmitted. A patient in a medical encounter wants the best, most accurate representation. In general, it is considered appropriate for the cultural and ethnic characteristics of the interpreter to match those of the patient.
Overall, it is important that the individual's voice, whether spoken or signed, be presented clearly and accurately by a qualified interpreter, especially in clinical and hospital settings, where information must be transmitted accurately and completely.
When scheduling an interpreter, those charged with hiring should consider the nature of the visit and its content. Sharing this information in advance provides the spoken or sign language interpreter the opportunity to prepare. Preparation includes such activities as identifying terms that might not exist in both languages. In addition, recruiters should consider ethnic and gender characteristics, especially when the gender of the interpreter is relevant to the health care visit, such as in reproductive health care for either men or women, or other issues that the individual perceives as intimate, e.g., physical or psychological trauma.
Of course, considering all these factors is not always practical, and at times, the match will not be perfect. For example, because proportionally there are more women in the field of interpreting than there are men, it is not uncommon for a male client to have a female interpreter.
Gesture and Miscommunication
Gestures are movements of the hands, arms, head, and other parts of the body that convey meaning and/or serve interactive functions. Research has focused on spontaneous gestures that co-occur with speech and are beneath the level of conscious recall [17]. Unlike conventionalized gestures, spontaneous gestures do not have prescribed, predictable forms, yet they reveal aspects of thought that are not verbalized.
One finding of gesture research especially relevant for clinician-patient interaction, with potentially the biggest impact on patient health, is back-channeling. "Back-channeling" refers to the recipient's signals of attention to the conversation. Often, they are verbal and overlap with the doctor's speech, including utterances such as "uh-huh," "oh, really," and similar listening cues.
Equally common gestures, however, include head nods in American and many other cultures [23]. The rate of nodding varies across cultures, and some countries, such as Bulgaria, use lateral shakes (akin to the American head movement for negation) as back channels instead. Cultures use whichever head movement (if any) is associated with affirmation to back-channel.
If the patient is back-channeling using nods associated with affirmation, it can be very tempting for overworked health care personnel to ignore vacant expressions in a patient's eyes and facial expressions of confusion. Such nods, however, do not signal understanding—they signal only attentive listening.
Research has shown that speakers often request listener back channels by nodding while they themselves are speaking [16]. Listeners often respond with their own nods almost immediately if the speaker is nodding as well. Such back-channel requests are beneath the level of conscious recall, so health care professionals may unwittingly be triggering back-channeling in patients, which is then misinterpreted as understanding or assent. This challenge works both ways.
Additional Challenges for Interpreters
The authors have identified many what might be called traditional or technical challenges for interpreters working in medical settings, but much needs to be learned about the full range of interpersonal challenges for these professionals. In a 2016 qualitative study of the experiences of interpreters who supported the transition from oncology to palliative care, researchers identified the study aims:
Medical consultations focused on managing the transition to palliative care are interpersonally challenging and require high levels of communicative competence. In the context of non-English speaking patients, communication challenges are further complicated due to the requirement of interpreting; a process with the potential to add intense layers of complexity in the clinical encounter, such as misunderstanding, misrepresentation and power imbalances [15].
The sensitivity of this specific example seems to be a likely proxy for all such emotional and complicated interactions. The investigators conclude:
The results suggest that interpreters face a range of often concealed interpersonal and interprofessional challenges and recognition of such dynamics will help provide necessary support for these key stakeholders in the transition
to palliative care. Enriched understanding of interpreters' experiences has clinical implications on improving how health professionals interact and work with interpreters in this sensitive setting [15].
The authors of this perspective urge attention to the needs of the interpreter in addition to the needs of the patient and the medical team.
Interpreters and Translators in Health Care
It is possible to approach the problems related to interpreting and translating more comprehensively and systematically, but doing so requires strategy, organizational commitment, planning, training, and budget. Two examples of such comprehensive and systematic approaches are those provided by Language Line Solutions and the Health Care Interpreter Network (HCIN).
Language Line Solutions, originally known as Communication and Language Line (CALL) was founded in 1982 in San Jose, California to help police communicate with some 65,000 Vietnamese refugees in the area. Language Line provides interpretation and translation services for law enforcement, health care organizations, legal courts, schools, and businesses.
HCIN was originated by Contra Costa Health Services in California. HCIN is focused on medical interpreting and offers an instantly accessible interpreting network and cost-effective videophone medical interpreting in 38 spoken languages and in American Sign Language. HCIN provides by-appointment video or phone health care interpreting in approximately 60 additional languages.
Both organizations provide continuing education for professional interpreters through online platforms. For example, HCIN Learn offers a three-hour course covering interpreting for prenatal genetic counseling that is described as covering concepts in human genetics, the work of counselors who advise about prenatal genetics and, specifically, guidance on the challenges in interpreting that arise in this setting. The course also provides technical language and practice elements for interpreters.
In the introduction to a manuscript examining HCIN, Jacobs et al. argue that "providing health care in a language that the patient can understand is a moral imperative. Allowing patients with limited English proficiency to receive sub-standard care and consequently be at risk for disparities in care, health, and well-being is unacceptable, especially in light of the breadth of linguistic access services available, even in remote areas" [14]. HCIN has been successfully adopted by Contra Costa Health Services, and is now utilized in 50 health clinics and hospitals throughout the system.
Translation, Interpretation, and Quality Improvement
Quality improvement in all programs dealing with patients and medical staff across languages constitutes an important element of understanding the full impact of language access and services. One model for discussion of the quality of services is based on the National Academies of Sciences, Engineering, and Medicine's six quality domains of safety, timeliness, effectiveness, efficiency, equity, and patient-centeredness [18]. Each of these domains can pertain directly to opportunities to improve the quality of translation and interpretation in medical settings.
As an example of how quality improvement in interpretation can be implemented is provided in a modular resource from the Agency for Healthcare Research and Quality (AHRQ). The free and multifaceted TeamSTEPPS Limited English Proficiency module trains health care teams to work with interpreters [2]. It also prompts interpreters to speak up if they discern a safety issue. As the site notes, citing Divi and colleagues, "Recent research suggests that adverse events that affect limited-English-proficient (LEP) patients are more frequently caused by communication problems and are more likely to result in serious harm compared to English-speaking patients" [11].
Teach Back and Interpretation
In Sudore and Schillinger's article on interventions to improve care for patients with limited health literacy, they operationalize the teach-back method [21], which can also be used to ensure quality during interpretation sessions: "The teach back method is a technique in which the clinician asks patients to restate or demonstrate the knowledge or technique just taught" [21]. A patient-centered strategy includes assessing how well the patient understands the information the physician provides, using a methodical and sensitive approach that requires the medical professional to be alert to the needs of the patient. Important elements of the teach back method include (a) confirmation of understanding, (b) reinforcement, and (c) numeracy and presenting risk information.
The authors note that asking "Do you have any questions?" or "Do you understand?" does not confirm understanding. Instead, the authors recommend asking "What questions do you have?" In an earlier work, Schillinger and colleagues also recommend that the physician destigmatize interactions by putting the responsibility back on themselves, stating, for example, "I've just said a lot of things. To make sure I did a good job and explained things clearly, can you describe to me . . . ?" [20]. In that same study, Schillinger notes that the method "does not result in longer visits and has been associated with diabetic patients having better metabolic control" [20]. These techniques also allow the provider to emphasize important health information, conveyed via the interpreter, in a culturally sensitive manner.
Universal Precautions and Health Literacy
The second edition of the AHRQ's "Health Literacy Universal Precautions Toolkit" describes health literacy universal precautions as "the steps that practices take when they assume that all patients may have difficulty comprehending health information and accessing health services" [4]. The precautions include the following elements: (a) simplifying communication with and confirming comprehension for all patients to minimize the risk of miscommunication, (b) making the office environment and health care system easier to navigate, and (c) supporting patients' efforts to improve their health.
AHRQ also provides its rationale for this approach:
Experts recommend assuming that everyone may have difficulty understanding and creating an environment where all patients can thrive. Only 12 percent of U.S. adults have the health literacy skills needed to manage the demands of our complex health care system, and even these individuals' ability to absorb and use health information can be compromised by stress or illness. Like with blood safety, universal precautions should be taken to address health literacy because we can't know which patients are challenged by health care information and tasks at any given time. It is important to bring this same principle of assuming the likelihood of difficulties in comprehension into any interpretation between language settings. This will help lessen the risk of miscommunication. [4]
Not all medical interactions are in hospitals or offices. In a discussion of patient communication in palliative care and hospice settings, Alves and Meier note: "Doctors practice as we are trained" [6].
The competing and stressful pressures on clinicians are complicated by a myriad of elements, outlined in Brigham and colleagues' National Academies article "A Journey to Construct an All-Encompassing Conceptual Model of Factors Affecting Clinician Well-Being and Resilience" [7]. This important effort to have a holistic view of the provider might well be matched with a similar model for the patient and for the interpreter. The conceptual model presented in the Brigham paper, which considers clinicians, patients, families and caregivers, and all of the aspects that influence all of their behaviors, provides an important starting place for the effort to provide a holistic view of the provider and the health care system.
Measuring Patient Experiences with Interpreter Services
Since 1995, AHRQ has offered the Consumer Assessment of Healthcare Providers and Systems (CAHPS) to advance scientific understanding of the patient's experience with health care [3]. AHRQ has developed a series of resources to be used in medical settings, including specific, freely-available supplemental surveys that assess patient and provider experiences with interpreter services in medical settings [1]. AHRQ data are a rich resource for internal analysis and shared data comparisons. Among other items, patients are asked about their needs for services, the services provided, the timeliness of the services, and the quality of the interpreter. Sample survey questions include
"How often did this interpreter treat you with courtesy and respect?"
"Using any number from 0 to 10, where 0 is the worst interpreter possible and 10 is the best interpreter possible, what number would you use to rate this interpreter?"
"How often did you use a friend or family member as an interpreter when you talked with this provider?"
"Did you use a child younger than 18 to help you talk with this provider?"
Different CAHPS surveys use slightly different questions about interpreter services [5]. For example, Hospital CAHPS includes the question, "During this hospital stay, did hospital staff tell you that you had a right to interpreter services free of charge?"
Pitfalls of Electronic Interpretation as a Solution
The introduction of handheld, speech-driven electronic interpretation devices seems, at first, to address many of the problems that arise when providers and patients do not speak the same language. However, these devices lack the precision and flexibility required for medical interactions. Devices render words that sound alike such as "oral" and "aural)" or "optic" and the suffix "otic"), but have, often critically differing meanings. Words that are said out of context, or words that are unfamiliar can stymie effective rendering of communication. Devices aren't able to differentiate or understand any miscommunication in the range of meanings of a word such as "PAP," which can vary from "the common gynecological test of a PAP smear," to "positive airway pressure," to "a synonym for soft or baby food" lacking the cues for context. Such a device could also have difficulty relaying like-sounding words such as dysphagia (difficulty in swallowing) and dysphasia (a brain injury that complicates communication or makes it impossible). Machines are improving, but they are not the solution in many medical settings.
Having reviewed the many challenges related to language, interpretation, and translation in health care settings, the authors of this manuscript believe that improving communication via interpretation and/or translation between clinicians and patients depends on (a) strategic preparation; (b) careful and consistent implementation of rules; and, as with any significant effort, (c) commitment to improvement through experience.
Much research is needed regarding the intersections of language, interpretation, translation, and health literacy. Immediate research needs include comparisons across varying methods of interpretation and translation services and the effectiveness of specific methods and tools. The impact of nonverbal cues and gestures in medical settings need greater attention. There is also a need for better understanding of how to bring individuals from differing cultural perspectives into the processes that directly affect them.
The authors of this manuscript offer below a few suggestions for developing habits that health care providers may find helpful. The suggestions are followed by a short checklist (on the following page) that can be used in the clinical setting.
Planning Ahead: Clinical Setting
If possible, prior to a first encounter with a patient who communicates in a different language than yours, consider: how might my staff and I determine what language preferences and accommodations are needed for effective communication with the individual?
This is also a good time to think about what materials might be provided and how they will be used.
Additional questions to ask yourself and your team are: How will I manage the time in the appointment? Do I have a good resource for evaluating the credentials of any interpreters? Are there going to be any special needs for the interpreter, such as a gown or a mask? Has the interpreter been prepared for the interaction to make the most effective use of their skills? (E.g., the following introduction for an interpreter: "Today, the patient is going to be told he is going to undergo chemotherapy. This fact sheet will be used by a patient who speaks Portuguese, and I will be explaining how the medication works and what to expect.")
Remember, each time, to look at the individual (your attention is important), not the interpreter.
During the Patient Encounter: Clinical Setting
Focus on the patient. Looking the patient in the eye will help in judging their level of understanding. Ensure that you are talking to the individual, not the interpreter or a family member. This will help ensure that the patient makes their own decisions in the encounter.
Ask yourself: Will embarrassment about topics, culture, age, or the presence of family members in the room keep my patient from telling me the truth? Have I used the teach-back method to confirm my patient understands me? (E.g., "Please, tell me what I've asked you to do? How will you take this medication? When do you need to be rechecked?")
After the Patient Encounter: Clinical Setting
Ask yourself: How did it go? Are there any adjustments I need to make for the next interaction with this patient or any other individual who speaks a different language? Are there any adjustments I need to make in working with an interpreter, either in person or by teleconference?
Tweet this! As the US becomes more diverse, language and translation are becoming increasingly critical parts of practicing medicine. The authors of this #NAMPerspectives urge clinicians to consider these issues before they are sitting with from a patient: https://doi.org/10.31478/202002c
Tweet this! Authors of a #NAMPerspectives discussion paper make clear that "while all interpreters, by definition, are bilingual, not every bilingual person can interpret" in a call for skilled interpreters to be embedded in clinician-patient conversations: https://doi.org/10.31478/202002c
Tweet this! Electronic interpretation devices seem to address many interpretation problems, but they currently lack the precision and flexibility required for medical interactions. Read about more challenges and potential solutions: https://doi.org/10.31478/202002c #NAMPerspectives
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Agency for Healthcare Research and Quality (AHRQ). 2017. Supplemental items for the CAHPS hospital survey: Interpreter services. Available at: https://www.ahrq.gov/cahps/surveys-guidance/item-sets/literacy/suppl-interpreter-service-items.html (accessed January 14, 2020).
AHRQ. 2017. TeamSTEPPS limited English proficiency module. Available at: https://www.ahrq.gov/teamstepps/lep/index.html (accessed May 9, 2019).
AHRQ. 2018. CAHPS hospital survey. Available at: https://www.ahrq.gov/cahps/surveys-guidance/hospital/index.html (accessed May 9, 2019).
AHRQ. 2019. AHRQ health literacy universal precautions toolkit. Available at: https://www.ahrq.gov/health-literacy/quality-resources/tools/literacytoolkit/index.html (accessed January 14, 2020).
AHRQ. 2019. CAHPS surveys and guidance: What are CAHPS surveys? Available at: http://www.ahrq.gov/cahps/surveys-guidance/index.html (accessed May 8, 2019).
Alves, B. and D. Meier. 2015. Health Literacy and Palliative Care: What Really Happens to Patients. NAM Perspectives. Commentary, National Academy of Medicine, Washington, DC. https://doi.org/10.31478/201512c
Brigham, T., C. Barden, A. L. Dopp, A. Hengerer, J. Kaplan, B. Malone, C. Martin, M. McHugh, and L. M. Nora. 2018. A Journey to Construct an All-Encompassing Conceptual Model of Factors Affecting Clinician Well-Being and Resilience. NAM Perspectives. Discussion Paper, National Academy of Medicine, Washington, DC. https://doi.org/10.31478/201801b
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Flores, G. 2006. Language barriers to health care in the united states. New England Journal of Medicine 355(3):229-231.
Jacobs, E. A., G. S. Leos, P. J. Rathouz, and P. Fu, Jr. 2011. Shared networks of interpreter services, at relatively low cost, can help providers serve patients with limited English skills. Health Affairs (Millwood) 30(10):1930-1938. https://doi.org/10.1377/hlthaff .2011.0667
Kirby, E., A. Broom, P. Good, V. Bowden, and Z. Lwin. 2017. Experiences of interpreters in supporting the transition from oncology to palliative care: A qualitative study. Asia-Pacific Journal of Clinical Oncology 13(5):e497-e505. https://doi.org/10.1111/ajco.12563
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Schillinger, D., J. Piette, K. Grumbach, F. Wang, C. Wilson, C. Daher, K. Leong-Grotz, C. Castro, and A. B. Bindman. 2003. Closing the loop: Physician communication with diabetic patients who have low health literacy. Archives of Internal Medicine 163(1):83-90.
Sudore, R. L., and D. Schillinger. 2009. Interventions to improve care for patients with limited health literacy. Journal of Clinical Outcomes Management 16(1):20-29.
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Youdelman, M. 2009. What's in a word? A guide to understanding interpreting and translation in health care. Available at: https://9kqpw4dcaw91s37kozm5jx17-wpengine.netdna-ssl.com/wp-content/uploads/2019/01/Whats-in-a-Word-FINAL.pdf (accessed May 13, 2019).
Jacobs, B., A. M. Ryan, K. S. Henrichs, and B. D. Weiss. 2018. Medical Interpreters in Outpatient Practice. Annals of Family Medicine 16(1): 70-76. https://doi.org/10.1370/afm.2154
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https://doi.org/10.31478/202002c
Allen, M. P., R. E. Johnson, E. Z. McClave, and W. Alvarado-Little. 2020. Language, interpretation, and translation: A clarification and reference checklist in service of health literacy and cultural respect. NAM Perspectives. Discussion Paper. National Academies of Medicine, Washington, DC. https://doi.org/10.31478/202002c
Marin P. Allen, PhD, is the former Deputy Associate Director of the Office of Communications and Public Liaison in the Office of the Director, National Institutes of Health (retired). Robert E. Johnson, PhD, is Professor Emeritus, Department of Linguistics, Gallaudet University. Evelyn Z. McClave, PhD, is Professor Emerita of Linguistics California State University, Northridge. Wilma Alvarado-Little, MA, MSW, is Associate Commissioner,
New York State Department of Health, and Director, Office of Minority Health and Health Disparities Prevention.
The authors would like to acknowledge the important contributions of John P. Madison, PhD to this perspective and to the larger discussion. We would also like to express our gratitude to Melissa French and Alexis Wojtowicz for their support in the development of this document.
Conflict-of-Interest Disclosures
Ms. Alvarado-Little has no relevant financial or nonfinancial relationships to disclose. She contributed to this article based on her experience in the field of health literacy and cultural competency and the opinions and conclusions of the article do not represent the official position of the New York State Department of Health.
Questions or comments about this manuscript should be directed to Marin P. Allen at [email protected].
The views expressed in this paper are those of the authors and not necessarily of the authors' organizations, the National Academy of Medicine (NAM), or the National Academies of Sciences, Engineering, and Medicine (the National Academies). The paper is intended to help inform and stimulate discussion. It is not a report of the NAM or the National Academies. Copyright by the National Academy of Sciences. All rights reserved.
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Cinnamon can be used to help treat muscle spasms, vomiting, diarrhea, infections, the common cold, loss of appetite, and erectile dysfunction (ED).Cinnamon may lower blood sugar in people with type 1 or type 2 diabetes,according to Diabetes UK.However high quality research supporting the claim remains scarce.
The health benefits of cumin include its ability to aid in digestion, improve immunity and treat skin disorders, boils, piles, insomnia, respiratory disorders, asthma, bronchitis, common cold, lactation, anaemia, skin disorders, boils and cancer.
Sangri is plucked, dried and stored for use round the year. It can be eaten for several days after it has been cooked -- without refrigeration.
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Anti-psychotic, tranquilizing pharmaceutical products used in the treatment of some mental illnesses such as, but not limited to, schizophrenia.
"It may be helpful to refer briefly to the nature and effects of neuroleptics.
"These anti-psychotic drugs, psychotropic drugs or major tranquillizers, as they are sometimes called, are the most common form of treatment for schizophrenia and related mental illnesses. Their medical efficacy stems from their ability to minimize or control psychotic episodes or the symptoms associated with schizophrenia.
"In general, anti-psychotic drugs influence chemical transmissions to the brain, affecting both activatory and inhibitory functions. Because the therapeutic effect of the drugs is to reduce the level of psychotic thinking, it is virtually undisputed that they are mind-altering.
"Although neuroleptics are the drug of choice for treatment of patients diagnosed as schizophrenic, they are not a cure for the disorder but are said to work so as to a have beneficial effect on thought processes and the brain's ability to sort out and integrate perceptions and memory.
"The use of neuroleptics in the treatment of various psychoses is generally effective in improving the mental condition of the patient by alleviating the symptoms of mental disorder. It is clear, however, that they may not be helpful in every case.
"Moreover the efficacy of the drugs is complicated by a number of serious side effects which are associated with their use. These include a number of muscular side effects known as extra-pyramidal reactions: dystonia (muscle spasms, particularly in the face and arms, irregular flexing, writhing or grimacing and protrusion of the tongue); akathesia (internal restlessness or agitation, an inability to sit still); akinesia (physical immobility and lack of spontaneity); and Parkinsonisms (mask-like facial expression, drooling, muscle stiffness, tremors, shuffling gait). The drugs can also cause a number of non-muscular side effects, such as blurred vision, dry mouth and throat, weight gain, dizziness, fainting depression, low blood pressure and, less frequently, cardiovascular changes and, on occasion, sudden death.
"In short, it appears that although these drugs apparently operate so as to benefit many patients by alleviating their psychotic symptoms, they also carry with them significant, and often unpredictable, short term and long term risks of harmful side effects."
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2) Dental Implants – An implant involves many parts: implant, abutment, and crown. The implant is the actual screw, which is placed in the bone for stability. The crown –the part that looks like the actual tooth – is what sits on top of the implant, via the abutment. Most dentists are only able to place the crown and abutment, after the specialist has placed the implant. But because Dr. Seo gained extensive surgical experience at his residency, he is able to place the implant itself. Make Morton Ranch Dental your one stop shop for implants!
3) Extractions – When a tooth is too far decayed and it is causing a lot of pain, sometimes the only option is to take it out. Dr. Seo has extensive experience in removing all kinds of teeth, including wisdom teeth. At Morton Ranch Dental, we make sure to get the tooth 100% numb in order to make this as comfortable for the patient as possible. If needed, our dental clinic offers laughing gas or oral sedation to make the experience easier.
4) Laughing Gas and Oral Sedation – Dr. Seo is trained and certified in the implementation of laughing gas and oral sedation to make his patients more comfortable during procedures in our dental clinic.
5) Family Dentistry – Dr. Seo and staff are happy to see patients of all ages, and children as young as 3. We treat families all over Houston and the surrounding areas, and we've found that it's incredibly convenient when families share a dentist.
6) Dentistry for Kids – We know that going to the dentist for an adult can be difficult, but it can be a major challenge for a child. When treating kids, Dr. Seo makes your child feel at ease. One way of doing that is by using laughing gas, a very safe tool in managing a child's anxiety. He also uses a certain anesthesia technique, which takes a little longer, but virtually eliminates the pain associated with an injection, making our dental clinic the go-to choice when you're searching for a kids dentist. Oral sedation is also offered if needed. For the extreme cases, we refer to a great pediatric dentist. We think it's important to create a comfortable experience for the patient – especially the pediatric patient – so that as adults, a fear of the dentist will have not been developed. We wish to create a positive association to the dentist, which will last for a lifetime.
7) Cosmetic Dental Care – When you look in the mirror at your smile, do you feel confident? Happy? Or does the sight of your smile make you frown? Not to worry, since we offer a wide range of today's most popular cosmetic dental treatments. Whether you're in need of teeth whitening, composite fillings, porcelain bridges, or other options to create dazzling results, we can make it happen.
8) Restorative Dentistry – At some point, most of us will need our teeth restored. We may need a misaligned bite dealt with, old dental work repaired, or cosmetic fillings done. Whatever the issue, we'll first discuss a treatment plan with you. Then we'll carefully explain the process, so you can move forward with confidence.
9) Root Canal Therapy – Many dental services just treat problems on the outside of teeth. But Dr. Seo is able to go straight to the core. An untreated cavity or fractured tooth can cause intense pain and tooth discoloration. We're able to provide safe and effective root canal therapy.
10) Deep Cleaning/Gum Surgery – There is a pocket that exists between our teeth and gums. In health, the gums are tightly wound around the teeth, and these pockets are very small. In diseased gums, the gums are loose around the teeth, and they tend to trap debris and bacteria. This can cause bad breath, bleeding when brushing, and even bone loss leading to ultimate tooth loss! A deep cleaning is necessary to bring the gums back to health if they've been neglected. Sometimes gum surgery is needed to reduce these pockets so they don't trap the debris and bacteria anymore. All of this is done to maintain the healthy foundation of your teeth so you can eat and chew without issues.
Also, we suggest having exams and cleanings performed twice a year. By doing this, we're able to keep your smile bright, your teeth clean, and jump on any oral health issues while they're in the early stages. We can also help if you need wisdom teeth removal!
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Making mental healthcare more affordable for Singaporeans
Cindy has been struggling with her mental health for the past six years, and has found it extremely difficult to afford the costs for her treatment. It broke my heart when she shared that she had to starve to afford therapy. She is not alone.
The author notes that 130,000 Singaporeans could be foregoing mental health treatment a year due to cost concerns.
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Anthea Ong
By Anthea Ong
Many others, like her, continue to face significant barriers in affording mental healthcare in Singapore.
In a public consultation my team of volunteers and I conducted earlier this year for the Budget 2020 debates, two out of three of the 396 respondents indicated they faced issues in affording mental healthcare, even in public healthcare institutions.
These responses are especially stark in a country with plenty and a world-class healthcare system.
The recent recommendations by the MediShield Life Council to extend coverage for attempted suicide, self-inflicted injury, drug addiction and alcoholism are a step in the right direction but more needs to be done to enhance affordability of mental healthcare.
LACK OF AFFORDABLE MENTAL HEALTHCARE
Within the public healthcare system, a subsidised counselling session costs around S$30 to S$50 per session. Psychiatric medication may cost upwards of S$100 for monthly prescriptions of more costly anti-depressants.
Coupled with the necessity of funding therapy and medication over a longer period of time, many Singaporeans, particularly young people and those from lower income groups, are unable to bear such a financial burden.
The Singapore Mental Health Study 2016 found that 78.6 per cent of adults in Singapore with mental health conditions did not receive treatment in the past 12 months.
More worryingly, it found that three out of four respondents not seeking treatment cited concerns with high costs of treatment as a deterrent.
The same study found a 12-month prevalence of mental illness of 6.5 per cent among adult Singapore residents.
With a population of 3.52 million Singaporeans, this potentially translates to a treatment gap of more than 130,000 citizens forgoing treatment due to cost concerns every single year.
This is equivalent to the population of an entire town like Toa Payoh. Surely this boggles the mind.
LACK OF MENTAL HEALTH INSURANCE
Another aspect that contributes to the treatment gap is the lack of insurance cover for mental health conditions.
Studies from the World Health Organization (WHO) have revealed that across countries, the lack of insurance cover constitutes a significant factor in delaying access to treatment.
On this, a few progressive employers from the WorkWell Leaders Workgroup — a ground-up community which champions workplace mental wellbeing — and I are exploring how we can move the needle as a collective for mental health conditions to be included in group insurance policies for employees.
In the Committee of Supply debates in Parliament in March, I had suggested that the Ministry of Manpower work with insurance companies to ensure affordable premiums in mental health coverage for employees by pooling risks.
Apart from ensuring mental health coverage in insurance policies, claim limits should be established at appropriate rates to ensure bills can be paid for, especially given that mental health conditions are chronic in nature and require regular treatment sessions.
Hence, I would argue that existing MediShield and MediSave claim limits do not go far enough in addressing the costs of mental healthcare.
For example, the current MediSave claim limit for outpatient treatment of certain mental health conditions such as depression, anxiety and schizophrenia is S$500 per year.
This will be increased to S$700 next year for those with complex chronic conditions.
Yet this may not be sufficient for people like Colin, another respondent in the public consultation that my team conducted.
Colin used up all of the S$500 available for treating his bipolar disorder in less than six months, and now faces the prospect of not being able to afford treatment for the rest of the year.
While the increase in limit to S$700 next year would help somewhat, it will still be a challenge for him.
WHO and experts recommend weekly therapy sessions (even a few times a week if in crisis) for the first four to six weeks, and regularly after, for a more effective care and treatment process.
In the coming months and years, it is expected that the need for mental health and psychosocial support will substantially increase as Singapore navigates the job losses and economic difficulties caused by Covid-19.
I am therefore heartened that the Government has set up an inter-agency task force to provide a coordinated national response to Singaporeans' mental health arising from the pandemic.
For a start, I would suggest that the MediShield Life Council go further with its recent proposals to amend claim limits, and ensure parity between physical and mental health conditions.
A disparity of five times continues to exist between the proposed revisions for claim limits, between S$160 per day for inpatient psychiatric care and S$800 per day for normal ward services.
Ensuring parity will normalise mental health conditions and motivate those living with mental illnesses to step forward to seek help.
I would further suggest that the Ministry of Health (MOH) improve MediSave outpatient claim limits to at least S$1,000 per year for mental health conditions, to allow for all Singaporeans in need to attend their therapy sessions on a weekly basis as recommended by experts.
In a parliamentary response to my question, MOH revealed that fewer than one in 10 subsidised patients exceed MediSave's yearly withdrawal limit for inpatient psychiatric stays and fewer than three in 10 persons' subsidised bills exceed MediSave's daily withdrawal limit.
However, I would argue that these numbers need to be further calibrated to take into account those two-thirds of persons with mental health conditions who do not seek help as mentioned above.
Could these numbers be symptomatic of the low numbers of people coming forward to seek help because they do not think they can afford to, given the current subsidy levels?
Currently, the Community Health Assist Scheme (Chas) subsidises a maximum of S$125 per visit capped at S$500 per year under Chas Blue for anxiety, bipolar disorder, major depression and schizophrenia at certain clinics under the Mental Health General Practitioner Partnership Programme.
There is room to expand this further not just in terms of quantum, but to more clinics and beyond these four specific conditions. This will ensure mental healthcare is not out of reach for our vulnerable communities.
Increasing funding for and/or expanding the use of MediSave monies for consultation at government-funded community mental health agencies, such as Shan You Counselling, Silver Ribbon, Limitless and MindCare may be another area to look at.
With just 4.4 psychiatrists and 8.3 psychologists for every 100,000 Singaporeans, doing so will help to lighten the load on our public healthcare institutions.
A NATIONAL PRIORITY
Health Minister Gan Kim Yong gave his assurance that "no Singaporeans will be denied health care because they cannot afford it".
I view this commitment to affordability as inclusive of mental healthcare, for there is no health without mental health.
However, if we are to walk the talk that affordable mental healthcare is a national priority, much more needs to be done.
We must start by digging deeper into the low utilisation of MediSave withdrawals vis-a-vis the glaring treatment gap.
We must ensure parity between claim limits for physical and mental health conditions, sending a strong signal to every Singaporean that their mental health is just as important.
Mental health insurance must be part of the comprehensive and inclusive mental healthcare we strive for, just like the world-class healthcare system that we are known for.
This year's theme for World Mental Health Day on Oct 10 was Mental Health for All: Greater Investment, Greater Access. Everyone, everywhere.
The Government has promised to "conduct a whole-of-government review of its mental health strategy in the coming months" in response to parliamentary questions by Members of Parliament and myself in March 2020.
I share the same hope with Cindy that she will one day be able to see a specialist who will help her, and every other Singaporean in need, at a price that she can afford.
Anthea Ong is a former Nominated Member of Parliament, social entrepreneur (Hush TeaBar, A Good Space) and author of 50 Shades of Love. The names of the two persons with mental health conditions that she cited have been changed to protect their identities.
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Tartar, sometimes called dental calculus, is an accumulation of hardened plaque on the teeth. In this hardened form it is harder to remove than softer plaque. If you make an appointment at our dentist in Oakville, Ontario our dental hygienist will scale and polish your teeth and remove all plaque and tartar that is present.
When tartar is present on your teeth it is far more difficult to affectively brush and floss the teeth. Tartar that forms on top of the gum line can be serious, as acids released that are present in your mouth along with the bacteria can far more effectively destroy tooth enamel which can then proceed to cavity development and tooth decay.
The bacteria harboured in the tartar can damage and irritate gums. A mild form of gum disease can take hold called gingivitis due to tartar and plaque present on the teeth. Gum disease in its early stages can normally be stopped as long as the teeth are brushed and flossed regularly and given a routine clean by an Oakville, Ontario dentist.
If tartar is left untouched and gingivitis is not treated, it could lead on to a type of gum disease which is particularly serious called periodontitis, where pockets are created between the teeth and gums. These pockets are more prone to infection from the bacteria underneath the gums. Chemicals are released by the body's immune system aimed at combating the bacteria and the products the bacteria emit. This can lead to damage to the bone and tissues whose purpose is to keep the teeth fixed into place. This can sooner or later lead to the degrading of the bone and tooth loss.
What can be done to control tartar?
Use a soft bristled brush that can comfortably reach all regions of the mouth. There is some evidence that electric toothbrushes do a better cleaning job than manual toothbrushes. Next you should select fluoridated toothpaste. Typically toothpastes that contain pyrophosphates may help to prevent plaque from developing into tartar. The fluoride will assist in repairing any enamel damage too. Some toothpaste may contain triclosan which, as an antibiotic, has the ability to combat any bacteria situated in the plaque.
Flossing every day can eliminate the plaque that can stick in between your teeth and prevent the formation of tartar.
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Sea anemone sting
Contributors: Vidal Haddad Jr, MD, MS, PhD, Robert Norris MD, Joanne Feldman MD, MS
Sea anemones are colorful coelenterates (related to corals, jellyfish, and Portuguese man-of-war) with stinging cells (nematocysts). Over 1,000 species live within the tidal zones of tropical, subtropical, and temperate waters. They range in size from a few millimeters to more than 0.5 meters (1.7 feet).
Sea anemone stings typically occur when they are accidentally brushed up against or purposely touched by the unknowing. Initial symptoms vary from a prickly sensation to severe burning at the wound site. The pain increases in intensity and may extend proximally into local lymph nodes. After a few hours, the pain lessens, but a residual ache or itch may last for weeks.
The skin reaction varies by sea anemone species. The venom of some species produces painful urticarial lesions; others induce erythema and edema. Some lesions may eventually blister, and in severe cases, necrosis and ulceration may result. Secondary infection is possible. A typical skin reaction is an area with central pallor surrounded by a halo of erythema and petechial hemorrhage.
Systemic symptoms may be reported and include fever, chills, malaise, nausea, vomiting, abdominal pain, headache, delirium, and muscle spasms. Shock, fulminant liver failure, renal failure, and respiratory distress have been reported.
T63.631A – Toxic effect of contact with sea anemone, accidental, initial encounter
241835009 – Poisoning by sea anemone
Envenomations:
Coral injury
Fire coral sting
Sponge dermatitis
Jellyfish sting
Sea cucumber irritation
Marine worm contact
Captions Print View all Images (4)
Numerous erythematous and markedly edematous papules, some in linear arrays, on the forearm.
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Register By March 1st, 2019 and receive a free custom M2T-Blade upgrade with logo and name.
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*The use of the exclusively engineered M2T-Blade Tool in the treatment of soft tissue and fascial restrictions and Adhesions.
*Assessment, Physiology, Biomechanics, Functional Anatomy and treatment.
*Applications of IASTM as an effective method for treating movement, pain, and dysfunction in several Musculoskeletal conditions.
*Explain the concepts and theories behind the restoring optimal soft tissue quality & stimulate the acceleration of the body's natural response post injury.
*How to integrate IASTM with the application of Kinesiology Tape in MSK conditions to compliment and enhance the treatment and exercise outcomes.
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What are neutralizing antibodies – the immune system's superheroes
Author: Sebastian Fiedler, Lead Application Scientist Life Sciences at Fluidic Analytics
Infectious diseases—a problem of the past or the present?
Modern medicine has provided an exceptional set of tools to prevent and treat infectious diseases – conditions that used to decimate the human population with frightening regularity. As the world struggles to battle the COVID-19 pandemic, however, we are starkly reminded that infectious diseases are not merely a problem of the past.
It is not only global pandemics like COVID-19 that evade the tools of modern medicine. We are in fact fighting this battle every day and on multiple fronts. Humans remain under constant attack by bacteria and viruses, and even in modern times these pathogens still cause the death of millions of people around the world each year.
How do you catch an infectious disease?
Infectious diseases are caused by a variety of pathogenic microorganisms including bacteria, viruses, fungi and parasites. These pathogens typically enter our bodies through our mouths, eyes, noses or open wounds.
Once inside our bodies, these microorganisms take advantage of their new favorable environment and quickly start multiplying. This process can severely damage and even kill the host cells resulting in visible and often well-described symptoms of specific diseases.
Luckily, our bodies are not wholly without defense because the pathogens trigger an immune response to help fight the infection. This activity unfortunately can also create collateral damage within the body, with fever, rash, inflammation, and general malaise all hallmarks of an active immune response.
Thankfully, modern medicine has delivered powerful antibiotics that are effective at supporting our own immune response across a broad spectrum of bacterial pathogens. The treatment of viral infections, however, has been much more challenging, and reliable therapeutics have so far eluded our best efforts. The most effective approach to fighting viral infections still is prevention by using vaccines that prime the immune system prior to a first encounter.
What happens when a virus enters the body?
When a virus enters the human body, it literally "goes viral", producing as many copies of itself as possible. To do so, the virus exploits a cell's own metabolism to release the new virus copies into the body, initiating the infection cycle over and over again. Once cells are infected, their natural function is badly impaired and, even worse, they often die. The resulting deficit of functional cells is the cause of tissue and organ failure, sometimes to an extent that is fatal.
But as mentioned earlier, our immune system does not leave us defenseless against viruses. To prevent a large-scale viral spread in our bodies, several innate mechanisms protect us at each stage of infection.
The first time we encounter a novel virus it typically avoids detection by the immune system and is able to enter a healthy cell.
At this stage, this now-infected cell will utilize its internal defense mechanism to display fragments of the virus on its surface using special receptor proteins. This display of virus fragments alerts the body that the cell is infected and activates the immune system to kill and eliminate the cell before the virus can spread.
In addition, the infected cells will also produce molecules, called interferons, which directly interfere with the process of viral replication to slow down the reproduction rate. Interferons also send a handy warning signal to nearby cells to alert them of the growing viral threat.
[Application Note] Assessing Cross-reactivity of antibodies against SARS‑CoV‑1 and SARS‑CoV‑2
Antibodies – our best defense
The best defense against viruses, however, is to stop the infection in its tracks. This immune mechanism is made possible not by the cells themselves, but by antibodies which can identify and eliminate viruses before they start the infection cycle.
Over the course of our lives, our bodies produce thousands of different types of antibodies that comprise our antibody-mediated immune response. Antibodies are proteins that are produced by B cells, which are a specialized type of blood cell. Once produced, these antibodies patrol our circulatory system and tissues, ready to deal with the pathogens.
Antibodies have several mechanisms to prevent infections. They can either neutralize viruses directly to prohibit their entry into the host cell, or they can crowd around a virus to increase its visibility to other immune cells. Once bound to a virus, antibodies can also tag the virus for phagocytes, which in turn ingest and destroy the pathogen.
When a virus enters the human body, it literally "goes viral", producing as many copies of itself as possible.
Our antibodies' ability to recognize and bind to pathogens starts with their structure. Fully assembled antibodies resemble the shape of the letter "Y".
The top of the two "arms" of the "Y" is where the magic happens. Imagine the arms as thousands of different jigsaw-puzzle pieces that give each antibody a unique shape. Each of those antibody jigsaw-puzzle pieces has the potential to fit specific virus antigens while fitting poorly with others.
The better the antibody and antigen fit, the higher their affinity to each other. In other words, the stronger they bind to each other the more effective the antibody is at preventing infection by the virus.
Figure 1: The better the antibody and antigen fit, the stronger they bind to each other the more effective the antibody is at preventing infection by the virus.
How do neutralizing antibodies earn their superhero status?
To infect, viruses must first enter a healthy cell. They accomplish cell entry by binding to receptor molecules on the surface of their host cells. For example, SARS‑CoV‑2 utilizes so-called spike proteins on its surface for initial cell binding. These spike proteins fit perfectly to the shape of a receptor protein (ACE‑2 receptor) typically found on the surface of human lung cells. Once the virus spike protein binds to the receptors of the lung cells, the virus enters and begins to replicate.
Virus-neutralizing antibodies are designed to interfere with this binding event. To prevent entry to lung cells, an effective neutralizing antibody resembles the jigsaw-puzzle shape mimicking the lung-cell receptor ACE‑2. In fact, it displays an even better fit than the receptor itself, resulting in the virus surface becoming covered by antibodies. This in turn prevents the virus from entering the lung cells. Moreover, such antibody-covered viruses become very sticky and attract each other to form large virus clusters, which, unlike individual viruses, are more easily recognized by other immune cells.
Figure 2: Neutralizing antibodies bind to spike proteins on the surface of SARS-CoV-2 and prevent the virus from binding and entering the host cell. As each antibody can bind to two spike proteins from different viruses, the start forming virus clusters that can be better recognized and destroyed by phagocytes.
If antibodies offer such great protection, then why do some people become severely ill with COVID-19?
This raises the question as to why some patients experience mild symptoms of COVID-19 while others suffer severely, or even die from, an otherwise identical disease.
One hypothesis is that the progression and manifestation of the disease depends on the ability and strength of the antibodies in our bodies to protect us. It is believed that an antibody will be an effective neutralizer only if it fits perfectly to the shape of the spike proteins and therefore binds strongly to the virus (i.e., it binds with a high affinity).
If a patient's immune system produces only lower-affinity antibodies (or even non-neutralizing antibodies that do not block the receptor binding site of the spike protein at all), cellular protection becomes compromised, even though the immune system might try to compensate by producing increasing amounts of these weak or non-neutralizing antibodies.
So are there tests that assess if we have neutralizing antibodies?
Although it is reasonably straightforward to determine the presence of antibodies in COVID‑19 patients using standard but crude immunoassays such as ELISA tests, assessing the virus-neutralizing capacity of antibodies in patient serum still relies on a cell-based neutralization assays. Although these assays do assess whether serum antibodies have the ability to block replication of the virus, they have significant drawbacks. They often require live biological materials and strict biosafety regulations, and most importantly, they are slow.
Because they rely on the growth of living cells in culture, cell-based neutralization assays take several days to complete. During this time, a patient's infection continues to develop. A multi-day wait for clinically actionable information could lead to several days of isolation from loved ones and absence from work at best; or a severe deterioration of symptoms and death at worst.
Another limitation of cell-based neutralization assays specifically impacts the development of vaccines and antibody-based treatments. Current cell-based neutralization assays cannot characterize and quantify specific antigen–antibody interactions, but rather provide a binary readout of whether or not neutralizing antibodies are present. Because this binary outcome does not provide insights in the mechanisms of action of vaccines and therapeutics, key information about the relative effectiveness of vaccines or antibody-based treatments could be missed.
No-fuzz detection and characterization in hours, not days!
COVID-19 with all its impact on people, societies and everyday life, is a stark reminder that there is an urgent need in modern medicine for a test that informs patients, clinicians and researchers—in hours, not days—about the presence and, more importantly, the quality of neutralizing antibodies in their blood samples.
To address this need, we have created a rapid, cell-free, virus-neuralization assay based on our in-solution technology and made it available on our Fluidity One‑M instrument. The assay measures the binding interaction between the ACE-2 receptor and the SARS-CoV-2 spike protein, as well as the subsequent displacement of the spike protein in the presence of virus-neutralizing antibodies directly in patient serum, all within a couple of hours.
Figure 3: Our in-solution assay allows for the direct measurement of virus spike displacement from the ACE‑2 receptor in the presence of neutralizing antibodies.
We are excited that this easy and fast approach could make a positive impact on patients' lives and help researchers, clinicians and biopharma companies to better understand protective immunity and develop more effective vaccine and therapeutics candidates to fight COVID‑19 (more information on this test shortly).
Binding of Fc-engineered IgG antibodies to FcRn
Measuring protein interactions in blood – It's not as trivial as it sounds
Accurate Affinity Profiling of a SARS-CoV-2 Antibody in Serum
COVID-19: References and related content
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Pseudomonas chlororaphis strain PA23 has demonstrated biocontrol of Sclerotinia sclerotiorum (Lib.) de Bary, a fungal pathogen of canola (Brassica napus L.). The objectives of this research were two-fold: to optimize PA23 phyllosphere biocontrol and to investigate PA23's influence in the rhizosphere. PA23 demonstrated longevity when inoculated on B. napus under greenhouse conditions. Carbon source differentially effected growth rate and antifungal metabolite production of PA23 in culture. Carbon source did not have a significant effect on in vivo biocontrol. PA23 demonstrated biocontrol ability of the fungal root pathogens Rhizoctonia solani J.G. Kühn and Pythium ultimum Trow in radial diffusion assays. PA23's ability to promote seedling root growth was demonstrated in sterile growth pouches, but in a soil system these results were reversed. This research is essential for developing PA23 into an effective biocontrol agent in the phyllosphere and it opens the door for use of PA23 as a rhizosphere seed treatment.
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Together is a new resource for anyone affected by pediatric cancer - patients and their parents, family members, and friends.
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Ependymoma
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What is Ependymoma?
Ependymoma is a tumor of the brain and spinal cord. It is the 3rd most common malignant brain tumor in children. There are about 200 new cases of pediatric ependymoma in the United States each year.
Ependymomas are most common in children under 5 years of age. However, they may develop at any age.
Ependymomas grow from cells that line the fluid-filled ventricles of the brain and central canal of the spinal cord.
These tumors can sometimes spread through the cerebrospinal fluid (CSF).
In children, about 75% of ependymomas occur in the posterior fossa region of the brain, but they can also develop in other areas of the central nervous system (CNS). Depending on the location of the tumor, different parts of the CNS may be affected including the:
Many ependymomas form in the fourth ventricle in the posterior fossa. These tumors are most likely to affect the brain stem and cerebellum.
Treatment for ependymoma includes surgery to remove as much of the tumor as possible. Radiation therapy is often used along with surgery to kill any remaining cancer cells. Chemotherapy may also be used before or after surgery.
The survival rate for childhood ependymoma is 50-70%. Prognosis depends on the location of the tumor, the amount of tumor that can be removed with surgery, and features of the tumor cells. Doctors are learning more about the biology and molecular features of ependymoma. This information can help predict how a tumor might respond to treatment.
Ependymoma can come back after treatment, and children often need long-term care to watch for recurrence.
Many ependymomas form in the fourth ventricle in the posterior fossa region. Tumors in this location are most likely to affect the brain stem and cerebellum.
Risk Factors and Causes of Ependymoma
Most ependymomas occur in infants and young children under 5 years old.
Certain changes in genes and chromosomes within the tumor cell are associated with ependymoma. Usually, it is not known why these genetic changes occur.
Some children may be at increased risk for brain tumors including ependymoma due to neurofibromatosis type 2 (NF2), a rare inherited condition.
Symptoms of Ependymoma
Signs and symptoms of childhood ependymoma depend on several factors including the size and location of the tumor and the child's age and stage of development.
Ependymoma symptoms may include:
Nausea and vomiting, often worse in the morning
Back or neck pain
Loss of balance or problems walking
Leg weakness
Irritability or confusion
Problems urinating or change in bowel function
Increased head size in infants
As the tumor grows, it often blocks the normal flow of cerebrospinal fluid. This causes a buildup of fluid within the brain known as hydrocephalus. The fluid increases pressure in the brain (intracranial pressure). Many of the symptoms of ependymoma are due to hydrocephalus.
Diagnosis of Ependymoma
Physical exam and medical history
Neurological exam
A physical exam and medical history help doctors learn about symptoms, general health, past illness, and risk factors.
A neurological exam measures different aspects of brain function including memory, vision, hearing, muscle strength, balance, coordination, and reflexes.
Imaging tests are used to help identify the tumor. Magnetic resonance imaging (MRI) of the brain and spinal cord is the main imaging technique used to evaluate ependymoma. MRI is also done after surgery to see if any tumor remains.
A lumbar puncture may be performed to look for cancer cells in the cerebrospinal fluid.
A biopsy is used to diagnose ependymoma. In a biopsy, a small sample of the tumor is removed during surgery. A pathologist looks at the tissue sample under a microscope to identify the specific type and grade of ependymoma.
Grading and Staging of Ependymoma
Ependymoma tumors are identified by how they look under the microscope. They are generally classified as grade I, grade II, or grade III tumors. The more abnormal the cells look, the higher the grade. Children with ependymoma usually have tumors that are grade II (classic ependymoma) or III (anaplastic ependymoma).
Certain types of ependymoma tend to have a better outcome than other types. However, other factors also affect treatment and prognosis.
Tumor Subtypes Based on Histology
Grade I Subependymoma
Myxopapillary ependymoma
Grade II Classic ependymoma (includes papillary, clear cell, and tanycytic ependymoma)
Grade III Anaplastic ependymoma
Prognosis for Ependymoma
The overall 10-year survival for pediatric ependymoma is about 50-70%. The prognosis depends on multiple factors. Children with certain types of ependymoma tend to have a better chance for long-term survival. However, late recurrences or relapse (beyond 5 years) may occur.
Factors that influence chance of cure include:
Location of the tumor
Type and grade of the tumor
Whether the cancer is localized or has spread (metastasis)
If surgery can completely remove the tumor
Age at diagnosis
If the cancer has come back (relapse or recurrence)
Molecular features of the tumor
Molecular Classification of Ependymoma
Scientists are learning more about the molecular types of ependymoma. These advances can help doctors understand why patients with tumors in specific parts of the brain or tumors that develop at a certain age respond better to treatments. Doctors can use molecular classification of the tumor to help predict risk and plan treatments.
Specific changes in the molecular or genetic characteristics of the tumor cells may be considered higher risk. High risk ependymoma includes posterior fossa tumors with extra copies of the chromosome 1q (1q gain).
Doctors may also look for other molecular changes including:
supratentorial tumors with RELA fusion (C11orf95-RELA fusion)
supratentorial tumors with a YAP fusion
Certain tumor features make the disease harder to cure. Doctors may use molecular profiles of tumors to help plan treatments.
Ependymoma is hard to cure without successful surgery to remove the tumor. When surgery is incomplete or ependymoma recurs, the long-term prognosis is usually poor.
Treatment of Ependymoma
Treatment of ependymoma usually includes surgery followed by focal radiation therapy. Some patients may also receive chemotherapy. Treatment depends on the type and location of tumor, age of the child, and whether the tumor is newly diagnosed or recurrent.
Surgery to remove as much of the tumor as possible is the main treatment for ependymoma. The goal is gross total resection, or complete removal of the tumor. However, it may not always be possible to remove all of the tumor due to risk of damage to brain structures.
Risks of surgery depend on the size of the tumor and the specific region of the brain involved. Possible complications include damage to brain structures that control muscle movement, speaking, swallowing, or hearing.
Some children who have surgery for ependymoma develop posterior fossa syndrome. Symptoms usually develop within a few days after surgery and include changes in speech, swallowing, motor function, and emotions. Symptoms can be mild or severe, and most children improve over time. Read more about posterior fossa syndrome.
For patients with certain grade I tumors, surgery alone may be an effective treatment depending on tumor type, location, and the extent of resection. Some patients may have a second surgery after a course of chemotherapy to remove more of the tumor.
Radiation therapy is usually used after surgery for ependymoma except in infants. Focal radiation therapy to the tumor and a small margin of healthy tissue is generally preferred. The dose and volume of radiation depends on the type and location of the tumor and spread of disease. Because ependymoma does not respond as well to chemotherapy, radiation therapy is used in children more than 1 year of age.
Chemotherapy is often used along with focal radiation therapy and surgery. Chemotherapy may be used before surgery to make removal of the tumor safer and more complete. In very young children, especially infants who are less than 1 year of age, chemotherapy may be used to help delay radiation until the child is older. The chemotherapy treatment plan will depend on factors such as spread of disease and molecular features of the tumor. A combination of chemotherapy medicines is used to treat ependymoma. These medicines often include:
Other types of chemotherapy may also be used.
Children who have a recurrence of disease after initial surgery and radiation therapy may be offered treatment within a clinical trial. There is a lack of successful standard therapies for recurrent ependymoma. Clinical trials include the use of immunotherapy drugs targeting the immune system to help fight the cancer and targeted therapies acting on specific proteins in the tumor cells.
Some children with hydrocephalus due to ependymoma may have a shunt placed in the brain to prevent cerebrospinal fluid from building up. A shunt is a small tube that drains fluid from the brain.
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Sometimes an ependymoma can block the normal flow of cerebrospinal fluid (CSF). Hydrocephalus occurs when too much CSF builds up in the ventricles.
A shunt is a small tube that drains cerebrospinal fluid to prevent the build-up of fluid.
Current risk-based approaches to ependymoma treatment classify patients based on specific tumor features and predicted outcomes. Doctors consider:
Whether surgery completely removed the tumor
Presence of metastatic disease
Tumor histology
Genetic features of the tumor
The goal of a risk-based approach is to achieve cure while lowering the risk of treatment side effects. For low risk patients, lower intensity therapy can reduce long-term problems from radiation and chemotherapy. For high-risk patients, more intensive therapy can improve chance of survival.
Incorporating palliative care and support services such as rehabilitation, psychology and social work can help ependymoma patients and families manage symptoms, promote quality of life, and make care decisions.
Life after Ependymoma
Ongoing follow-up care, laboratory tests, and routine imaging are needed to monitor patients for recurrence of disease and other medical problems. The care team will set a schedule based on type of tumor, response to treatment, and individual patient needs.
Later relapse of ependymoma is more common compared to some other cancers. Most patients who relapse do so within 5 years of their diagnosis. However, these tumors can also recur after the 5-year milestone of cancer survival.
General Follow-Up Schedule for Ependymoma Survivors:
Years 0-3: MRI of the brain every 3-4 months
Years 3-5: MRI of the brain every 6 months
After 5 years: MRI of the brain every 12 months for 2-5 more years
Survivors of CNS tumors are at risk for problems such as decreased cognitive function, hearing loss, sleep problems, hormone problems, stroke, and second cancers. These problems may be caused by the tumor itself or develop as long-term or late effects related to treatment. Regular checkups and screenings by a primary care physician are important to watch for health problems that can develop years after therapy.
Find More Information on Ependymoma
Collaborative Ependymoma Research Network
Ependymoma - St. Jude Children's Research Hospital
More: Life After Brain Tumors
Reviewed: July 2019
Magnetic resonance imaging (MRI) uses a large magnet, radio waves and computers to produce high-quality, detailed pictures of the inside of the body.
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Pediatric palliative care is a special type of supportive care for children facing a serious illness. Palliative care focuses on comfort and quality of life.
Learn about palliative care
Surgery plays an important role in the diagnosis, treatment and supportive care of many types of childhood cancers.
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Marking domains
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Research output: Contribution to conference › Other
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Politeness in interaction design
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Predicting non-adherence to HAART: the role of patients' doubts about personal need and concerns about potential adverse effects
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Preface for the Proceedings of Machine Learning Research Volume 152
Carlsson, L. (ed.), Luo, Z. (ed.), Cherubin, G. (ed.) & Nguyen, K. A. (ed.), 10 Sep 2021. 3 p.
Privacy Requirements: Findings and Lessons Learned in Developing a Privacy Platform
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Professional doctoral programmes in the UK – university of Brighton experience
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Prototyping the Internet of Place: Designing for Human Centred Complexity - Data Driven UX of loT and Smart Cities
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Psychological processes underlying personal recovery in bipolar disorder
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Quartz crystal Resonant sensors in the development of biosensor technology
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Rational and irrational elements in A. S. Puskin's view of historical conflict in Boris Godunov and Mednyj Vsadnik
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Reasoning with Diagrams: Observation, Inference and Overspecificity
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Reducing waiting lists: the development of referral guidelines for testicular ultrasound through a prospective audit
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Responding to, and Understanding Filicide. Challenges and Psychosocial Perspectives
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Rethinking educational technology: scenarios
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Risk, Anxiety and Social Work
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ABSTRACT Maisyalina Agustiana. Influence of Organization Commitment and Stress to Performance of PT. Kobelindo Compressors Employee. Essay, Jakarta: Office Administration Program Educational Studies, Department of Economics and Administration, Faculty of Economics, State University of Jakarta. 2013. The research aims to determine whether there is influence between organization commitment and stress to performance of PT. Kobelindo Compressors employee. The research was conducted at PT. Kobelindo Compressors for four months from March to Juny 2013. The method used is survey method with the causality approach. The study population was all employees of PT. Kobelindo Compressors, amounting to 78 people. Affordable population in this study were 49 people from Marketing Department, Product Support Department, and Service Department. Samples were taken by using proportional random sampling. Y Variable data in this study is secondary data. X1 Variable data (organization commitment) were measured using test score result of the primary data, through the measurements obtained from the respondents, a questionnaire with 37 statements the validity of the test number is 0,574... and realiability test is 0,949. And also with the X2 Variable data, has validity 0,523 and reliability 0,947. And for Y Variable data using secondary data from company. Test requirements analysis is used to find the regression equation obtained is Y = 0,462 X 1 – 0,423 X2 + 0,597 e2 dan R 2 yx 2 x1 = 0,597 where X1 =-0,642 X 2 + 0,346 ϵ1 and R2 x1 x2 = 0,412. The resuts of normality test signifivance value of performance (Y), organization commitment (X1) and stress (X2) is 0,200 which are all more than 0,05 H0 accepted then the data means normally distributed. The results of both hypothesis test variables of commitment organization and stress simultaneously have an influence on performance, as seen from F hitung (37,018) > Ftabel (3,21). Then the partial variables of commitment organization has thitung (3,802) > ttabel (2,02), it means organization commitment significantly influence performance. Stress has –thitung (-3,477) < -ttabel (-2,02), it means stress significantly influence peformance. Based on the research path analysis, the magnitude of the influence of organization commitment (X1) which directly on the perfromance (Y) is 21,3%. In addition to the magnitude of the effect of stress (X2) which is directly on performance is 17,9%. While the magnitude of the effect of stress to performance and moderated by organization commitment is -0,297. Thus the total effect of stress to perfromance was -0,72, which means that the performance is determined by organization commitment and stress. Conclussions of this study is that there are influences between organization commitment and stress to performance of PT. Kobelindo Compressors.
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Electric powered wheelchairs (EPWs) are an important form of mobility for many persons with disabilities. However, little quantitative data exists on how much people use their EPWs in real-world environments. Previous devices have been successful at measuring EPW usage, but they have been limited by the size or the battery life of the device. This study describes the design, development, and validation of caster data logger (CDL) suitable for long-term collection of EPW usage data in real-world environments. Also included in this study is a description of EPW usage data collected during and after the National Veterans' Wheelchair Games (NVWG). Several device concepts for logging EPW usage were evaluated. A caster data logger concept was chosen and functional prototypes were fabricated. The prototypes were subjected to a variety of bench tests before being deemed suitable for field use. 10 CDLs were constructed of data collection at the NVWG. At the NVWG, subjects who used an EPW as their primary means of mobility were recruited for this study. In 5 days at the games the participants (n=5) traveled a distance of 7751 ± 3439m per day, while traveling 3397±1300 m (n = 4) per day during 5 days the following week. The results were limited due to small sample size; however, they could provide useful pilot data for future studies.Overall, the CDL showed potential as a useful tool for measuring EPW usage. Future development should focus making the device easier for researchers and clinicians to use.
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Preclinical Murine Pharmacogenetics Core
From Mouse to Human: History
More Within Preclinical Murine Pharmacogenetics Core Preclinical Murine Pharmacogenetics Core
Mission of the Facility
How This Will Work
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In Vitro Target Validation
In Vivo Protocol Design and Implementation
John G. Clohessy, PhD
Director, Preclinical Murine Pharmacogenetics Facility Cancer Genetics Program
330 Brookline Avenue, CLS 402
APL as a novel paradigm for experimental therapeutics
Acute promyelocytic leukemia (APL) is associated with the accumulation in the bone marrow of tumor cells with promyelocytic features and the invariable association with specific reciprocal chromosomal translocations involving the retinoic acid receptor α (RARα) gene on chromosome 17. In the vast majority of cases (>98%), the RARα gene fuses to the promyelocytic leukemia gene, PML. In a small subset of cases, RARα has been found to fuse to several other genes that have recently been identified (such as PLZF) leading to the generation of X-RARα and RARα-X fusion proteins.
To evaluate the role of these fusion proteins in leukemogenesis, several groups have generated mouse models that express these fusion proteins in the myeloid compartment of the bone marrow under the control of hemopoietic tissue-specific promoters.
APL models in the mouse were not only faithful to the biology and pathological features of the human disease, but also their leukemias behaved exactly as APL in human patients when challenged with drugs.
For instance, APL in PML-RARα transgenic mice responds well to retinoic acid therapy. Precisely as in human APL, RA was able to induce complete remission in the mouse; but leukemia would eventually and inevitably relapse if treated with RA alone. In addition, leukemias in APL PML-RARα mouse models would often become RA-resistant as is the case for human t(15;17) APL, involving PML and RARα gene, treated solely with RA. Furthermore, it was also demonstrated that exactly as in human t(11;17) APL, involving the PLZF and RARα gene, leukemia in PLZF-RARα mice was found resistant to RA at presentation.
Following on, mouse models of APL began to inform clinical trials in place. Simply put, it was possible to advise the clinicians on how to stratify patients for clinical trials on the basis of genetic criteria, using information accrued in preclinical testing of mouse models of APL. As an example, it has been demonstrated that leukemia in PML-RARα mice was extremely responsive to As2O3 (which later on proved to be another powerful weapon for the treatment of APL), while once again leukemia in PLZF-RARa mice was found to be resistant. From then on t(15;17) APL was treated successfully with As2O3, while t(11;17) APL patients were not.
On the basis of these examples, novel therapeutic modalities could be tested as well as combinatorial treatments were optimized by utilizing these APL mouse models as a preclinical predictive engine toward APL eradication. . A decisive home run in this respect was the realization that As2O3 and RA in combination were tremendously effective in PML-RARa leukemia in the mouse.
On the basis of these convincing results, clinical trials combining both As2O3 and RA were subsequently performed in many academic enters in China, Europe and eventually in the U.S. Today, the As2O3 and RA combination is considered the standard of care in the treatment of t(15;17) APL. These two drugs specifically target the PML-RARa fusion protein by opposing its aberrant transcriptional activity and targeting it for degradation. As2O3 and RA are offered at presentation to t(15;17) APL patients as front line therapy with limited toxicity, in the absence of chemotherapy as induction or consolidation treatment. With these two drugs, curative complete remission is obtained in 100% of cases leading to disease eradication. Hence, the "targeted therapy devoid of chemotherapy" of APL has come of age. Once again, the preclinical effort in the mouse decisively informed and predicted clinical outcome.
In spite of the remarkable success for the treatment of t(15;17);PML-RARa APLs, the subtype of APL associated with PLZF-RARa fusion proteins remained nevertheless a very resilient subtype of APL, maintaining resistance to conventional chemotherapy as well as to RA and As2O3.. However, mouse models of t(11;17) APL have been successfully used to devise and test novel therapeutic modalities for therapy resistant APL that has lead to the approval from the FDA to test in therapy resistant human APL a combination of an HDAC inhibitor and RA.
APL is now considered eradicated and, as per today, 100% of patients attain complete remission and remain in durable remission off treatment with the sole use of combinatorial targeted therapies. Overall, APL represents the paradigm of how through preclinical studies in mouse models we can gain a substantial knowledge as to which therapies are efficacious and to which degree the molecular basis for human disease dictates the response to therapy.
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Discipline of General Practice, São Paulo University (USP). São Paulo-SP.
Department of General Practice, University of Liège (DUMG ULg).
This article presents an overview of different techniques and skills necessary for teaching and learning quaternary prevention (P4). It adopts the Expertise Model that defines the competences required in P4 for each level: novice, competent, proficient, and expert. This framework should be used as a step-wise roadmap for teachers in order to achieve high levels of performance. This proposal is complemented by a list of methods applied in teaching and assessment of learners' performance and competence. By covering a range of learning and teaching issues, those who aim to teach quaternary prevention can explore the proposed framework. Quaternary prevention is a research and teaching fertile medical field that entails the integration of different areas such as health service organisation, epidemiology, communication skills, and andragogy either at the macro or the micro levels of health related activities.
Quaternary Prevention; Teaching; Education, Medical; Family Practice; Internship and Residency.
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Received 2018 April 5; Revised 2018 June 10; Accepted 2018 June 11.
In the personalized medicine era, utilizing paraffin blocks in pathology archives for investigating human diseases has come into the limelight. This archived material with clinical data will reduce the research time and could prevent new patient recruitment to obtain tissue for research. However, the clause indicating the necessity of consent from human material providers in the Korean Bioethics and Safety Act has made the Institutional Review Board (IRB) deny permission to use paraffin blocks for research without consent, and alternatively to get the same before starting an experiment. Written consent may be waived off in studies using paraffin blocks with anonymous status or conditions not linked to personal information by applying the paragraph 3, article 16 of the current Bioethics and Safety Act. Also, the IRB should recommend researchers to preserve the blocks as medical records of patients in long-term archives.
Paraffin blocks archived in the department of pathology are made from patient tissues obtained for diagnostic or therapeutic purposes. Excised tissues from different clinical departments are transferred to the pathology department, where the specimen is examined by a pathologist and sections with diagnostic significance are selected and obtained. These sections eventually turn into paraffin blocks after going through several histologic processes, including dehydration and embedding. Slides for microscopic examination are made when 4-6-μm thickness ribbons from these paraffin blocks are attached onto a glass slide and stained. Paraffin blocks are reusable for different examinations (i.e. special staining or reexamination) and therefore managed and stored in the department of pathology. In addition, these blocks can serve as legal evidences supporting the fact that the patient has undergone surgical treatment. Hence, these blocks are considered as medical records and are usually stored for at least 5 years in majority of the hospitals.
Recent advancements in research methods have allowed diverse studies using paraffin blocks, including the extraction of deoxyribonucleic acid (DNA) from these blocks to perform genetic testing for oncogene identification and therapeutics. Furthermore, a key advantage is that prospective tissue collection can be avoided by utilizing long archived material, dramatically shortening the study period. More specifically, follow-up medical records can also be used in parallel, and therefore paraffin blocks have become an important study material for personalized medicine.
Since paraffin blocks are human derivatives, study approval from an Institutional Review Board (IRB) is essential based on the Korean Bioethics and Safety Act. However, in most cases, paraffin blocks are collected during the treatment process and consent obtained from the patients is for surgery and not for research. Consequently, decisions made by IRBs based on the Korean Bioethics and Safety Act are often not uniform. More specifically, different IRBs make different decisions based on the consent forms, and some studies are unable to proceed due to lack of approval. Therefore, we aim to suggest review points for studies using paraffin blocks based on the Korean Bioethics and Safety Act, in order to assist IRBs with a consistent and uniform review process and promote novel studies in the field.
The definition of 'human biologic material' based on the Korean Bioethics and Safety Act revised in 2015 is 'all tissues, cells, bloods, or body fluids, as well as serum, plasma, chromosomes, DNA, ribonucleic acid, or proteins extracted from them(chapter 1, article 2)'. Paraffin blocks are made of cells and tissues extracted during surgery or biopsy and therefore are human derivatives. Consequently, the patient's consent as well as IRB approval is essential for research purposes.
The Korean Bioethics and Safety Act article 16 (consent from human subjects for research) section 1 indicates that "investigators utilizing human samples must obtain written consent from the human subjects prior to the study". However, written consent may be waived in certain cases. Article 16 paragraph 3 indicates that "despite the content in section 1, obtaining written consent from patients may be waived if the following conditions are met and IRB approval is obtained": 1) cases where obtaining written consent from the patient is practically impossible or will have severe effect on validity of the study; 2) cases where no evidence is provided to assume withdrawal of consent and rare or not greater than minimal risk would be put upon the patient even if s/he withdrew consent.
Human derivatives in paraffin blocks are biological specimens extracted or resected for diagnostic and therapeutic purposes, but not for research purposes. In other words, these are human specimens extracted with the patient's consent and can be discarded based on the Waste Management Act article 2 no. 5 (human biomaterial or extractions from medical institutions). Therefore, consent provided for surgery should also be sufficient for extraction and legal management of the extracted materials after the surgery. In addition, 'agreement for extraction' should be considered as 'the patient has given up on the extracted tissue'. Whether additional consent from the patient is required when using their tissue — which they have either given up or given consent to extract — for additional research purposes is questionable. Consent forms for utilizing human biomaterial required by the Korean Bioethics and Safety Act should initially reflect the use of extracted material for research purposes, separate from the cases where tissues are extracted for diagnosis and treatment initially and the remaining tissue is used for research purposes. The principles discussed and utilized by the American Society for Clinical Pathology also suggest that "the patient has given up on the extracted tissue", and the remaining specimen or paraffin blocks after diagnosis can freely be used for research purposes without an additional consent process .
However, other people argue that the consent provided by the patient for surgery is for discarding their extracted tissue after the surgery and not for utilizing the tissue for research purposes. Therefore, they suggest that approval for further research should be obtained initially and an additional consent is required if no appropriate consent was obtained initially. Some of the IRBs that support this idea conclude that "paraffin blocks archived in the pathology department were not approved for research and therefore cannot be used for research purposes ".
IRB should examine the study proposal and decide whether the study fulfills conditions for waived consent outlined in the Korean Bioethics and Safety Act article 16 paragraph 3, instead of assuming that consent is essential for studies utilizing human biomaterial. Let us apply the condition 1) "cases where obtaining written consent from the patient is practically impossible or will have severe effect on validity of the study". In most studies using paraffin blocks, it is practically impossible to obtain written consent from the participant (patient who provided the specimen). This is because majority of studies using paraffin blocks utilize blocks that have been stored for several years and therefore it is difficult to be in touch with these patients. More specifically for paraffin blocks from malignant tumor tissues, the patient may have deceased. It is questionable whether contacting the patients by telephone or email, after searching for their personal information from medical records, just to obtain additional consent is ensuring the autonomy of these specimen providers—which is a fundamental bioethical principle. In fact, this may infringe on the patient's personal information and reveal sensitive information. Therefore, forcing the process of obtaining consent may be invading the patient's privacy. Moreover, majority of studies try to utilize as many tissue samples as possible to test statistical significance, and delay in studies due to the process of obtaining consent is inevitable. However, if an IRB decides that the study requires additional consent from the patients, large number of paraffin blocks being used in the study cannot be a reason for waived consent.
Moreover, the investigator should be able to explain that the study is fulfilling the conditions outlined in article 16 paragraph 3. 2) Cases where minimal physical or mental risks are put upon the patient even if additional consent not obtained. Since the study utilizes tissues extracted from surgery, there is no additional physical pain inflicted on the patients. In addition, there is no mental or social risk if there is no personal contact between the investigator and the patient. Therefore, an IRB can allow waived consent for the studies that do not utilize personal information, by utilizing anonymous data. Nonetheless, if the study requires special information or follow-up and consequently requires personal contact with the patient, an additional consent will be essential.
Medical Appliances Act allows for utilization of specimens for clinical trials without additional consent, if data anonymity is ensured. Article 24 paragraph 1 indicates that the following specimens can be used without consent form with anonymized data: "12. following specimens ("remaining specimen" from here on) being used in clinical trials without obtained consent from paragraph 1 no. 4 should be used with anonymized personal data for the specimen providers: A. specimen from remaining human derivatives originally extracted for diagnostic or therapeutic purposes; B. specimens from remaining human derivatives originally extracted for specific research purposes, being used for secondary purpose (with comprehensive consent)".
Newly published "guidelines for understanding the conditions for waived consent when assessing study protocols utilizing remaining specimens to be discarded in the hospital" by the department of bioethical policy in August 2017 has remedied these shortcomings . This guideline also suggests that specimen can be used without additional consent, given that the data is anonymized.
When evaluating the study protocols utilizing paraffin blocks, not only bioethical aspects including consent forms, but also the fact that paraffin blocks are stored as a type of medical record, should be considered. Current "Medical Legislation Enforcement Regulations" article 15 (maintenance of medical records) indicates that paraffin blocks should be a type of medical record like radiologic imaging, and minimum of 5 years storage is mandatory. Although paraffin blocks or pathological slides are not included in the regulation, they should also be managed and stored in the same way. The Korean Society of Pathology suggests that these materials should be stored for more than 5 years along with other medical records .
Forced storage of these tissue blocks not only preserves continuous diagnosis and treatment history of the patient but also allows them to act as a legal evidence. Furthermore, storing these paraffin blocks and slides allows additional consultation with experts from different institutes and novel diagnostic methods can be applied on these past samples. Therefore, the blocks to be used for research purposes should be assessed, regardless of whether it violates the patient's right to receive better diagnosis and treatment. If there are several blocks and only one is being used for the study, there should not be an issue. However, the investigator should not use the specimen if there is one remaining block for the patient or if there will be no remaining block after using the sections for the study . In the study proposal, the investigators must agree that they will not use the block if 'there is one last remaining block for the patient' or they will obtain non-stainedglass slides if 'there is one last remaining block for the patient'.
In addition, considering that enforced storage period for medical records is 5 years, one can claim that paraffin blocks older than 5 years may be used without an additional consent form.
Studies utilizing paraffin blocks, based on the content of the study, can be exempted for IRB review according to the Korean Bioethics and Safety Act article 36 paragraph 2. According to paragraph 2 no. 1, following cases can have IRB review exempted if "the investigator does not collect or record personal information": "A. studies utilizing human biomaterial and relevant genetic information collected and stored by the human biobank, where personal information cannot be assessed without going through the human biobank that provided the samples; B. studies that assess quality control of laboratories or quality assurance of data using remaining human biomaterial after diagnostic and therapeutic uses; C. studies that use separated/manufactured study material (i.e. pathogen, cell culture) from human biomaterial; and D. studies where the investigator does not have access to personal information of the specimen donor and no genetic relationship is found between study outcome and genetic information of the donor —except for studies using embryonic stem cells". In summary, paraffin block-utilizing studies where 'the investigator has no information on personal identification and the study is not investigating a hereditary trait' are exempted from review. However, the exemption of IRB review is not equivalent to waived consent obtaining and therefore these should be evaluated separately. There are claims suggesting that paraffin blocks should be considered as 'B. remaining human biomaterial after diagnoses' and can only be used for 'quality control', and therefore cannot be used for research purposes. This leads us to believe that the Korean Bioethics and Safety Act was focusing on the human biomaterial collected for research purpose, lacking the awareness of diverse human biomaterial produced for diagnostic and therapeutic purposes.
In this study, we have emphasized the value of paraffin blocks in medical research and summarized the possibility of waived written consent for paraffin block-utilizing studies under the Korean Bioethics and Safety Act. Current Act article 16 paragraph 3 suggests the possibility of waived written consent for studies utilizing paraffin blocks, and article 36 paragraph 2 demonstrates potential exemption of IRB review. Therefore, IRB should ask the investigator to explain that it is practically impossible to obtain written consent for the proposed study and there would be no potential threats or risks on the specimen provider even if the study proceeds without consent. Thereafter, validity of this explanation should be examined by the IRB. Lastly, considering that paraffin blocks are a type of medical record, the study investigator must ensure that the paraffin block is not damaged so that potential demands in the future by the specimen provider can be addressed.
1. Dry S. Who owns diagnostic tissue blocks? Lab Med 2009;40:69–73.
2. Information Portal of Institutional Review Boards designated by the Ministry of Health and Welfare. 100 questions and 100 answers. 2013 to 2014 collection of open writings 30 Sejong: Ministry of Health and Welfare; 2015.
3. Department of Bioethics Policy, ; Ministry of Health and Welfare. Guidelines for understanding the conditions for waived consent when assessing study protocols utilizing remaining specimens to be discarded in the hospital [Internet]. Sejong: Ministry of Health and Welfare; 2017. [cited 2018 April 30]. https://bci.gilhospital.com/BlueAD/board.php?bbs_id=gc_notice&bbs_no=184&mode=view&type=6.
4. Korean Society of Pathologists/Korean Society for Cytopatholgy. Pathology red book for quality assurance 2018 [Internet] Seoul: Korean Society of Pathologists/Korean Society for Cytopatholgy; 2018. p. 25–6. [cited 2018 April 30]. http://www.pathology.or.kr/html/?pmode=boardview&MMC_pid=251&seq=18362.
5. Kim YJ, Park JS, Ko K, Jeong CR. Let archived paraffin blocks be utilized for research with waiver of informed consent. J Pathol Transl Med 2018;52:141–7.
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Effects of acute and chronic cooling on ...
Effects of acute and chronic cooling on cardiorespiratory depression in rodents
Deveci D. , Egginton S.
JOURNAL OF PHYSIOLOGICAL SCIENCES, cilt.57, ss.73-79, 2007 (SCI İndekslerine Giren Dergi)
Doi Numarası: 10.2170/physiolsci.rp005906
Dergi Adı: JOURNAL OF PHYSIOLOGICAL SCIENCES
The cardiovascular and ventilatory responses of the Wistar rat (a nonhibernator) and the Syrian hamster (a hibernator) to acute and chronic cold exposure were investigated. The acute lowering of core temperature (T-c = 22 degrees C, hypothermia) compared with normothermia (T-c = 37 degrees C) and hyperthermia (T-c = 40 degrees C) was used to examine the underlying differences in the extent of cold adaptation. In euthermic rats, acutely induced hypothermia resulted in a pronounced reduction in heart rate (f(H) reduced by 55%; P < 0.01), a modest but significant elevation of mean arterial blood pressure (mABP increased by 16%; P < 0.05), and a marked reduction in respiratory frequency (f(R) reduced by 64%; P < 0.01). All parameters returned to baseline values on returning T-c to 37 degrees C, with a modest overshoot on acute hyperthermia. These data are consistent with the depressive effect of low temperature on biological rate functions and increased vagal tone in the cold, while matching f(R) to a lowered metabolic rate (MO2). Cold acclimation had little effect on this pattern of response, suggesting that any adaptive increase in thermogenesis is limited. Euthermic hamsters also showed a significant reduction in fH on acute cooling (74%; P < 0.01). In contrast to rats, hamsters developed a significant decrease in mABP (52%; P < 0.01) and maintained a relatively high f(R) (4%; n.s.). These data suggest a resetting of the baroreflex and relative hyperventilation, consistent with an elevated MO2 associated with enhanced nonshivering thermogenesis. Cold acclimation had little effect on thermal sensitivity, though the response curves were displaced to produce a relative hypertension and tachycardia at a given T-c. These data suggest a reduced cardiorespiratory coupling in the hibernator compared with the nonhibernator.
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Americans of Indian Punjabi descent who are concerned about gluten sensitivity might want to get tested for Celiac disease.
According to a new study on American patients, Indian-American Punjabis are more likely to be diagnosed with Celiac disease than other ethnicities in the US, and men and women of all ethnicities are equally likely to live with the condition.
Celiac disease is an autoimmune disorder that inhibits the body's ability to digest gluten. An autoimmune disorder is one in which the body's immune system, which defends the body against disease, unintentionally attacks itself. Gluten is a protein found in wheat, barley and rye. Symptoms of celiac disease include indigestion, vomiting, diarrhea, fatigue, migraines and joint pain. If left untreated, celiac disease can lead to other disorders like diabetes, neurological problems, infertility, intestinal cancers, migraines and other autoimmune disorders like multiple sclerosis (when the body attacks its own nervous system), anemia (lacking healthy red blood cells) and dermatitis herpetiformis (chronically dry and itchy skin).
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Reading: Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Ca...
Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications
Seungheon Han,
Institute of International Affairs, Seoul National University, Seoul; Program in Global Surgery and Implementation Science, JW LEE Center for Global Medicine, Seoul National University College of Medicine, Seoul, KR
Sugy Choi,
Department of Health Law, Policy & Management, Boston University School of Public Health, Boston, Massachusetts, US; Program in Global Surgery and Implementation Science, JW LEE Center for Global Medicine, Seoul National University College of Medicine, Seoul, KR
Jongho Heo,
National Assembly Futures Institute, Seoul; Program in Global Surgery and Implementation Science, JW LEE Center for Global Medicine, Seoul National University College of Medicine, Seoul, KR
Jayoung Park,
Program in Global Surgery and Implementation Science, JW LEE Center for Global Medicine, Seoul National University College of Medicine, Seoul, KR
Woong-Han Kim
Program in Global Surgery and Implementation Science, JW LEE Center for Global Medicine, Seoul National University College of Medicine, Seoul; Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine, Seoul; Department of Thoracic and Cardiovascular Surgery, Seoul National University Children's Hospital, Seoul, KR
About Woong-Han
Background: Most children who have congenital heart disease in low- and middle-income countries (LMICs), including Uzbekistan, do not receive adequate and timely pediatric cardiac surgical care. To strengthen the surgical capacity of a local pediatric cardiac surgery team in Tashkent, Uzbekistan, the JW LEE Center for Global Medicine at Seoul National University College of Medicine has developed a team-based training program and has been collaboratively conducting surgeries and care in order to transfer on-site knowledge and skills from 2009 to 2019.
Objectives: To evaluate the long-term effects of the collaborative program on the cardiac surgical capacity of medical staff (teamwork, surgical complexity, and patients' pre-surgical weights) as well as changes in the lives of the patients and their families. To derive lessons and challenges for other pediatric cardiac surgical programs in LMICs.
Methods: To assess the effects of this ten-year long program, a mixed-methods design was developed to examine the trend of surgical complexity measured by Risk Adjustment for Congenital Heart Surgery 1 score (RACHS-1) and patients' pre-surgical weights via medical record review (surgical cases: n = 107) during the decade. Qualitative data was analyzed from in-depth interviews (n = 31) with Uzbek and Korean medical staff (n = 10; n = 4) and caregivers (n = 17).
Findings: During the decade, the average RACHS-1 of the cases increased from 1.9 in 2010 to 2.78 in 2019. The average weight of patients decreased by 2.8 kg from 13 kg to 10.2 kg during the decade. Qualitative findings show that the surgical capacity, as well as attitudes toward patients and colleagues of the Uzbek medical staff, improved through the effective collaboration between the Uzbek and Korean teams. Changes in the lives of patients and their families were also found following successful surgery.
Conclusions: Team-based training of the workforce in Uzbekistan was effective in improving the surgical skills, teamwork, and attitudes of medical staff, in addition, a positive impact on the life of patients and their families was demonstrated. It can be an effective solution to facilitate improvements in pediatric cardiovascular disease in LMICs if training is sustained over a long period.
How to Cite: Han, S., Choi, S., Heo, J., Park, J. and Kim, W.-H., 2020. Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications. Annals of Global Health, 86(1), p.107. DOI: http://doi.org/10.5334/aogh.2883
Published on 25 Aug 2020
Cardiovascular disease is the major cause of mortality around the world [1]. In particular, congenital heart disease, the most common congenital malformation, exhibits negative and long-lasting health and socioeconomic consequences for individuals and society. Most children who have congenital heart disease in low- and middle-income countries (LMICs) do not receive adequate care [2], and about 70% of the congenital heart disease cases in babies require medical or surgical care in their first year [3]. However, few LMICs can provide adequate and timely pediatric cardiac surgical care. It is estimated that approximately 58% of the congenital heart disease burden can be averted if surgical practices from high-income countries are applied to health care settings in LMICs [4]. Strengthening the surgical workforce is one of the ways to improve surgical care in LMICs [5, 6]. Training the workforce in pediatric cardiac surgery remains understudied despite its potential impact in LMICs.
Collaboration between a high-income country (HIC) team and an LMIC team has been emphasized as an effective method for successfully training the health care workforce in LMICs [2, 7, 8, 9, 10, 11]. The JW LEE Center for Global Medicine (CGM) at Seoul National University College of Medicine has developed a team-based training program to build up the surgical capacity of a local pediatric cardiac surgery team in Tashkent, Uzbekistan from 2009 to 2019. CGM transferred their knowledge and skills using the team-based training approach, which emphasized that surgical professionals in LMIC ought to build a team to provide effective surgical care. This methodology has been documented to effectively transfer knowledge among professionals as well as increase positive surgical outcomes by facilitating communication and empathy between team members [12, 13, 14, 15]. A team is generally defined as two or more individuals working together to achieve common goals through sharing common targets, information, and resources based on mutual trust [14, 16]. Since the inherent characteristics of healthcare are interdisciplinary, physicians, nurses, and other professionals from different specialties should work together in a team [14]. A considerable amount of literature confirms the effectiveness of this team-based approach among professionals as a critical contributory factor for successful surgical outcomes [13, 14, 15] and workforce training [2, 7, 8, 9].
The objective of this study was to assess the effects of this program throughout the ten-year period in Uzbekistan. To fully understand and strengthen the research findings [17, 18, 19, 20, 21, 22], the current study utilized a mixed-methods approach that combined quantitative and qualitative data to evaluate the program's effects from diverse aspects. Our study examined aspects which included: 1) Changes in teamwork and surgical skills in terms of the complexity of performed pediatric surgeries among surgical staff, and 2) changes in lives of patients and their families. From the findings, we inferred lessons and challenges for the next decade of the ongoing program and other pediatric cardiac programs in LMICs.
From 2009 to 2019, an assembled team of Korean cardiac surgeons, pediatric cardiologists, anesthesiologists, perfusionists, intensive care unit (ICU) nurses, administrative assistants, and researchers visited Uzbekistan annually in order to improve the knowledge and skills of pediatric cardiac surgery delivery and patient care in a team, using didactics, discussions, and hands-on training [23]. The Korean team and the Uzbek team engaged in all processes of diagnosis, surgical treatment, and pediatric intensive care. During morning and post-operation conferences, all gathered to recapitulate the surgical procedure of children who underwent open-heart surgery and to discuss the optimization of patient conditions. Didactics were provided according to the Uzbek team's needs. Unlike other mission teams from other HICs, this particular pediatric cardiac surgical capacity-building program was implemented with several principles: to recruit sicker or more complex patients that the Uzbek medical staff found difficult to operate on; to provide the Uzbek team opportunities to conduct complex surgical procedures collaboratively with the Korean team, or independently but under the supervision of the Korean team (depending on the complexity and familiarity of the cases); to support and emphasize local team-building; and to transfer knowledge and skills through team-based activities between the Korean and Uzbek teams. By virtue of the program's team-based training approach, the local surgery team would gain the ability to conduct self-sustainable open-heart surgery, ultimately improving access to cardiac care for children with congenital heart disease. The details have been published elsewhere [23]. The design, processes, and outcomes are expressed in a project design matrix for the on-site cardiac surgical capacity-building program in Uzbekistan (Figure 1).
A project design matrix for the on-site cardiac surgical capacity-building program in Uzbekistan.
Data collection and measures
Both quantitative and qualitative data were collected for the duration of the training program from 2010 to 2019. Chosen outcome indicators were teamwork and surgical skills of the medical staff, as our focus was on building teamwork in the local surgical team to increase surgical skills and survival through the collaborative program. Additionally, we checked outcomes from the patients' perspectives including changes in patients' health and family life.
First, to quantify the pediatric surgical capacities of the local team, quantitative data to measure surgical complexity during the program were collected via medical record review from 2010 to 2019 (surgical cases: n = 107). Measures included patient pre-operative weight (kg), diagnosis classification, and surgical procedure. Surgical procedures were grouped into six risk categories in the order of increasing mortality risk within a pediatric population using the Risk Adjustment for Congenital Heart Surgery 1 score (RACHS-1) classification [24, 25]. A greater number of categories in the RACHS-1 represents progressively more difficult surgical cases. RACHS-1 classification uses surgical procedures to predict the risk associated with the operation and the measure has been used in the context of developing countries [26, 27, 28]. Two cardiac surgeons independently coded the procedures using the RACHS-1 classification and agreed on the final assignment.
Qualitative data were collected via individual in-depth interviews. In total, 31 interviews were conducted with the Uzbek medical staff (n = 10), caregivers whose child had heart surgery (n = 17), and the Korean medical staff (n = 4), using purposive sampling for maximum variation in profession and length of participation in the surgical program (Table 1). For example, to collect enough information on the process and outcomes of the program, the Uzbek and Korean medical staff were selected as interviewees based on whether they participated in the program and worked together with the Korean staff during 2009–2019. Ranging from one to ten years, all medical staff have participated in the program. We also considered various professions to collect diverse perspectives on the program. Although we did not include the entire medical staff due to time limitations, we made an effort to collect quality data by probing the underlying meanings of their statements. Three interview sessions were conducted; from June 11–16, 2016; from May 13–18, 2017; and on Feb 21, 2020. Bilingual interviewers (Uzbek-Korean) used semi-structured guides to conduct interviews. All interviews were conducted after receiving consent for participation.
Characteristics of interview participants (N = 31).
Interview groups
Year of interview
Interview Participants
ICU Nurse
Ward Nurse
Scrub Nurse
Uzbekistan medical staff
(N = 10) 2016 2 1 – – – 2 –
2017 2 – – 1 1 – 1
2020 – – – – – – –
Korean medical staff
(N = 4) 2016 – – – – – – –
2017 1 – 1 – 1 – –
2020 – – – – 1 – –
(N = 17) 2016 14
Unit: Number of people; ICU: intensive care unit.
We generated different in-depth interview questions according to the interviewee groups. For the Uzbek and Korean medical staff, interviews were conducted to explore the role of the training program, the results of the program, and challenges for developing pediatric medical capacities in Uzbekistan. For caregivers, interviews were conducted to explore a detailed history of the child's health issues, child's health and daily life before and after surgery, and life changes of caregivers and other family members before and after surgery. Interviews were conducted in a private room at the hospital, and each interview lasted about 30 minutes on average. All interviews were audio-recorded and transcribed verbatim in Uzbek by a professional transcriber and then translated into Korean.
For quantitative data analysis, we presented descriptive statistics of the diagnosis classification. To show increases in pediatric surgical capacity within a decade, average outcome values of patients' RACHS-1 score, pre-operative weight (kg), weight by year, and linear prediction lines were presented. We depicted the linear regression coefficients, 95% confidence intervals, and p-values in the figures (* indicates p < 0.1, ** p < 0.05, and *** p < 0.001). STATA MP 15 (StataCorp, College Station, TX) was used to conduct all quantitative analyses.
For qualitative data analysis, the thematic analyses of qualitative data involved a collaborative process [29]. We used open coding of transcripts to identify key words, phrases, and statements. All researchers read each transcript and identified notable words, phrases, and patterns from the participants' responses. Finally, responses were categorized into themes related to the research topics of each interviewee group. All quotes are extracted from individual interviews and names are not shown to protect confidentiality.
Ethical approval and consent to participate
The study protocol was approved by institutional review boards at Seoul National University College of Medicine (IRB 1908-122-1056). Study participation was voluntary and written informed consent in the local language (Uzbek or Korean) was obtained from all participants. Surveyors and interviewers trained in ethical matters collected all data.
Quantitative findings: increasing surgical complexity and decreasing pre-operative weight
A total of 107 patients received cardiac surgery during the training program from 2010 to 2019. All patients survived to discharge. Table 2 shows operation characteristics during the training when the Korean team was present.
Annual patient operation records during the training, 2010–2019.
N 10 11 11 13 12 11 10 10 10 9 107
Gender, N
Female 6 8 4 6 2 7 6 2 5 4 50
Male 4 3 7 7 10 4 4 8 5 5 57
Age, months
Mean 35.9 46.1 35.8 30.2 31.1 16.3 26.3 12.3 42.2 22.3 30.0
(SD) (30.2) (38.3) (40.5) (22.0) (37.1) (31.7) (27.4) (11.1) (41.0) (25.3) (32.1)
Mean 13.0 13.9 11.8 10.3 11.2 6.7 9.1 6.2 12.1 10.2 10.5
(SD) (8.5) (5.1) (7.4) (4.3) (5.7) (5.6) (4.8) (3.2) (8.2) (6.3) (6.3)
Risk Category, RACHS-1
Mean 1.9 2 2.4 2.2 2.4 2.7 2.5 2.6 3 2.8 2.4
Trainers and trainees mostly performed ventricular septal defect (VSD) (18.7%), Tetralogy of Fallot (TOF) (15.9%), single ventricle (15.0%), and total anomalous pulmonary venous return (TAPVR) cases (13.1%). All cases were placed into categories below 5 (Table 3).
Diagnosis Classification, 2010–2019.
Diagnosis Classification
N (%) Total = 107
Ventricular septal defect (VSD) 20 (18.7)
Tetralogy of Fallot (TOF) 17 (15.9)
Single Ventricle 16 (15.0)
Total anomalous pulmonary venous return (TAPVR) 14 (13.1)
Coarctation of the aorta (CoA) 5 (4.7)
Transposition of the great arteries (TGA), VSD 5 (4.7)
CoA-VSD 3 (2.8)
Ebstein's anomaly 3 (2.8)
Atrial septal defect (ASD) 2 (1.9)
Complete atrioventricular septal defect (AVSD) 2 (1.9)
Interrupted aortic arch (IAA) 2 (1.9)
Pulmonary atresia with an intact ventricular septum (PA-IVS) 2 (1.9)
Pulmonary atresia with ventricular septal defect (PA-VSD) 2 (1.9)
Complete AVSD with TOF 1 (0.9)
Complete TGA with IVS 1 (0.9)
Complete TGA with VSD 1 (0.9)
Double outlet right ventricle (DORV) with PS (Fallot type) 1 (0.9)
Intracardiac mass 1 (0.9)
Partial anomalous pulmonary venous return (PAPVR) 1 (0.9)
Posterior interventricular artery (PDA) 1 (0.9)
Partial AVSD 1 (0.9)
Pulmonary atresia with VSD 1 (0.9)
Tricuspid Atresia (TA) 1 (0.9)
TAPVR-ASD 1 (0.9)
TOF-PA 1 (0.9)
VSD-ASD 1 (0.9)
VSD-PS 1 (0.9)
Figure 2a shows the unadjusted trends in surgical complexity (RACHS-1) of the cases from 2010 to 2019. On average, the RACHS-1 score increased from 1.9 in 2010 to 2.78 in 2019, showing a gradually increasing trend, and was statistically significant at p < 0.001. Starting in 2018, more than half of the cases exhibited higher severity, where they were assigned 3 or 4 (2018 = 70.0%, 2019 = 55.6%).
Surgery data and patient characteristics.
Figure 2b shows the unadjusted pre-operative weights of the patients. The average weight of patients decreased by 2.8 kg from 2010 to 2019, thus showing a gradual decrease trend with yearly fluctuation (p = 0.031). The lowest weight was 2.6 kg for a patient who had surgery in 2015. The lowest average patient weight was 6.2 kg, that was achieved in 2017.
Figure 2c shows the unadjusted trends in patient age from 2010 to 2019. The average age of patients (in months) decreased from 35.9 months to 22.3 months (p = 0.102).
Qualitative findings
Theme 1: Effective surgical capacity-building with collaborative team-based training
The development of pediatric cardiac surgery in Uzbekistan over the past decade has been supported by effective teamwork between the Korean and Uzbek medical staff. Most Uzbek medical staff emphasized that they could develop their own specialized medical skills and competencies through the Korean 'whole team' approach which included major departments such as cardiac surgery, cardiology, anesthesiology, perfusion, ICU nursing, and scrub nursing. According to interviews, other foreign countries had dispatched only one or two surgeons who returned to their home country after operating. In this circumstance, it was difficult for the Uzbek medical staff to learn and develop the expertise they needed.
The other overseas teams came and did not speak to us. However, the Korean team already formed their team before coming here, so it was different from other overseas cases. Each member spoke to its respective counterpart. For example, the anesthesiologists spoke to the anesthesiologists, the internal medicine doctors talked to the internal medicine doctors, and the nurses talked to the nurses. Each Uzbek medical staffer spoke to the Korean medical staffer according to their own department. In doing so, the whole (Uzbek) team developed together. (Uzbek medical staff 5, 2016)
Only two or three people came from the teams from XX, XX, and XX University, and only the surgeon came to do the surgery. But when they did that, the results were not good, and we did not learn much from each other. However, the Korean team came with a team of nurses, surgeons, anesthesiologists, and so on. The result was good and there were many things to learn. The greatest advantage was working together with the team based on roles. (Uzbek medical staff 4, 2016)
Previously, only doctors could calculate an amount of medicine, but nurses were able to do it themselves after training by the Korean team. The Korean nurses taught us how to weigh a newborn baby. Doctors only inform patients about their medications, but now, nurses can do it. It is important for nurses to learn from nurses. (Uzbek medical staff 3, 2017)
Theme 2: Medical staff's change in perception and behavior towards patients and colleagues
In addition to the surgical skills that the Korean medical staff directly transferred through teamwork, the perception and behavior of the local medical staff also positively changed in various aspects, including work ethic, responsible attitude toward dealing with colleagues and patients, and perception of teamwork.
As the most noticeable change, the local medical staff were motivated to work harder with sincerity due to the Korean staff working respectably among them.
The Korean team respected each other and taught us a lot. After seeing how the Korean team worked, we said, 'Let's do this too!' (Uzbek medical staff 3, 2017)
I learned from the Korean team how to communicate with patients. (Uzbek medical staff 1, 2017)
Usually, we only performed simple cases, but the Korean team performed difficult and complex ones. After the Korean team visited, our doctors and nurses worked harder. We began to open our books and study complex cases. This was a critical change in our team. (Uzbek medical staff 4, 2017)
Furthermore, the local medical staff became aware of the importance of teamwork while working with the Korean medical staff. Most participants stated that effective teamwork is one of the most important factors for more sustainable and successful surgery in the future.
The Korean team taught us 'teamwork.' They always emphasized, 'Do not think that this is your patient if you conduct the surgery and this is my patient if I conduct the surgery. This is our patient whether the surgery is conducted by you or me.' They also stressed that every member of the medical staff should make an effort to maintain the patients' health irrespective of who conducts the surgery. Finally, we felt that we should work together for our patients' health. (Uzbek medical staff 6, 2016)
It is common in Uzbekistan hospitals for doctors to usually make their own decisions. However, I think that the outcome of the surgery is good only if every team member does their own work in the team. No matter how well the thoracic surgeon does, a poor anesthesiologist cannot give patients good results. (Uzbek medical staff 1, 2017)
At the beginning of the program, the Uzbek medical staff felt that the obligation to take care of patients rested only on the medical staff who were involved in the surgery. During the ten year-long training, however, they realized that all medical staff were responsible for all patients' health, and they had to closely collaborate for successful surgical outcomes.
Theme 3: Life changes among patients, caregivers, and family members
Since most patients presented complex cases that were difficult for the Uzbek medical staff to successfully operate on, the patients and their caregivers, or family members, were satisfied with the results of the surgery conducted with collaboration between the Korean and Uzbek teams, and they experienced extensive life changes. Most of all, the surgery resulted in better health conditions, including higher physical performance for the children, which led to higher school attendance rates. Additionally, before surgery, the caregivers had to constrain their daily consumption because of high medical expenses involved in caring for heart disease, such as payments for transportation, medicine, and special meals for patients, and so on. After surgery, however, households could use their income for buying other necessary materials or save for the future.
After surgery, my child changed 100%. She does not catch cold or get sick anymore. She started walking and her growth increased gradually. (Caregiver 4, 2016)
Before the child had surgery, the family worried a lot. We were stressed out because we did not know if our child would survive. The atmosphere in the house was grim, and at that time I thought about leaving the family. (Caregiver 3, 2016)
The majority of caregivers were patients' mothers. Prior to surgery, they could not participate in other economic activities or chores since they cared for their children. Some of them even felt guilty due to their child's heart condition. After surgery, however, most caregivers began to lead their own life as a worker, housewife, or student. All these positive changes improved the quality of life of other family members as well.
Because my child was sick, I had to take care of my child all day. I could not do anything else or go anywhere. (Caregiver 1, 2016)
I wanted to continually study after having a child, but I could not. Now that my child is healthy, I want to start working or studying. (Caregiver 1, 2016)
Theme 4: Challenges for next steps
Although the results showed positive effects in the capacity-building of the Uzbek medical staff and improvements in the quality of life of patients, several challenges remain as critical barriers to sustainably implement the program in the future.
The biggest obstacle was the lack of Korean medical volunteers. However, the composition of volunteers in every visit was also a challenging factor for the program's sustainability.
Lack of Korean staff is always a challenging problem. While some of the staff travel there (Uzbek) as a business trip due to their hospital officially allowing them, based on the MOU [Memorandum of Understanding] with the JW LEE Center, the majority spend their personal vacation. In general, there are not enough nurses in each hospital, so it is hard for them to join this volunteer trip. (Korean medical staff 1, 2020)
It is difficult to recruit volunteers for every visit to Uzbekistan. However, I believe the greater concern is that the team's composition is always changing because the members come from different hospitals. Since the medical styles and standards performed in each hospital are slightly different, the educational content which is taught to the Uzbek medical staff is not standardized. Although we had a workshop to share our common understandings, it was insufficient according to me. Given that the recruitment of medical staff will become more difficult in the future and its composition will change every time, it is urgent to prepare a standardized education manual for future intervention. (Korean medical staff 1, 2020)
Additionally, insufficient administrative and political support from the local hospital was also a limitation in developing the program.
While the Korean team taught us how to operate on complex cases, we could not continually conduct these surgeries after their visit as the hospital forbade the surgery of complex cases. The hospital was concerned that patients with significant difficulties would die because the hospital did not trust the surgical capabilities of the local medical staff. (Uzbek medical staff 4, 2016)
The hospital prohibited medical staff from conducting complex cases due to concerns about poor surgical outcomes. This prohibition might impede Uzbek surgical development by limiting the opportunities for conducting difficult surgery.
This study evaluated the effects of a ten-year-long cardiac surgical capacity-building program in Uzbekistan using mixed-methods. As a strength of this study, the mixed-methods approach allowed us to quantify the effects of the capacity-building program and to understand how team-based training was rooted in these effects. Through quantitative analysis, we showed that, as training progressed, both teams performed complex surgery cases and operated on patients with lower weights. The qualitative results also highlighted that team-based training, as a method of capacity-building, is one of the critical facilitators that improved the knowledge and skills of the local medical staff; and the developed capacity positively influenced the successful surgical outcomes and life changes among patients and their family members as well. Given the interview results, team-based training and activities reinforced the local team's capacity [30].
It is noteworthy that the local staff were given the opportunity to perform complex cases with the Korean medical team and at times independently, under supervision of the Korean team, to develop their medical capacity [2, 7, 31]. According to the interviews, other foreign medical mission teams conducted surgery by themselves and the local staff were not given a chance to operate independently, or even under supervision, thereby creating difficulties in learning complex surgical skills. In contrast, this program empowered local staff by suggesting that they should lead complex surgical cases after adequate training under supervision of the visiting team. As previous studies have shown, close collaboration between the visiting team and the local team is an important way to effectively transfer medical knowledge and skills to the local medical staff [2, 7, 8, 9]. Particularly, the Korean team educated the local team by matching their specialty, and this side-by-side training optimized the learning quality by not being constrained to a specific area and considering the local staff's needs [7, 32, 33]. For instance, the two teams had multiple opportunities to discuss medical issues, such as future treatment plans, and care for patients in the ICU through formal or informal activities. They worked together at the hospital all week long, resulting in a trustworthy relationship.
The perceptions and behaviors of local medical staff toward patients changed as a result of the training team's emphasis on a collective perspective regarding patients' surgery outcomes. Before participating in this program, the local staff reported that they did not share the responsibility of a single patient and believed the individual who conducted surgery on the patient was the only one responsible. This mindset is common among physicians [7]. However, the local team learned to share responsibilities for both the processes and results of surgery after participating in the program, leading to a change in an important behavior that might facilitate positive results in health-professional training [7].
Our findings also provide four main challenges to the implementation of future programs in a more sustainable way. First, it is a critical challenge to recruit enough Korean medical volunteers in all specialties who can visit and conduct this program in LMICs. Although the recruitment of a sufficient number of skilled volunteers is essential to transfer medical skills to a local team [9, 31, 34], a large workload in Korean hospitals often hinders recruitment of the necessary volunteers at the right time. It will be possible to reduce the visiting team size if the local team's capabilities are sufficiently improved [31, 32]; but if not, then having an ample number of volunteers in diverse specialties is a critical precondition to successfully transmit medical skills to the local medical staff. Additionally, an online-based training program can be considered as an alternative to hands-on-training, and it can help to reduce the burden of recruiting human resources for conducting capacity-building programs [9, 35].
Second, it is important to establish the team's shared standards of medical operation for standardizing the training contents. Basically, the Korean surgical team composition was heterogeneous in medical background and experience because they were recruited from different hospitals. However, as our interviews and previous study have shown, it is important that all visiting members share a common understanding of medical operation before each visit in order to increase educational effectiveness by reducing these discrepancies [32]. To do so, standardized guidelines have to be established in the near future.
Third, although our program sustained for a decade to support the development of capacity and independence of the Uzbek medical team, a new strategy for the next decade should be established aiming to complete the independence of the Uzbek team [31]. As many studies have emphasized, establishment of a long-term strategy and commitment, of both the visiting team and the local receiving team, is one of the critical factors for the successful development of medical capacities in LMIC settings [1, 5, 31, 36]. However, as other LMICs also experienced [2, 31], insufficient support from the hospital administrators and funding to continue the program are important challenges for the near future [23]. Our ultimate goal should be to strengthen the team's clinical skills and to communicate with important stakeholders.
Finally, the outcomes of our program should be periodically measured and evaluated by collecting data for program sustainability [2, 5, 32, 33]. One of the limitations of our research was that we were not able to assess all surgical cases conducted at the institution because of time and cost constraints. In many cases, a well-established, well-managed database and quality assurance motivates all participants, as well as encourages achievement of the program's objectives [33, 37]. Data collection by the local medical team is also necessary to effectively monitor the interim outcomes themselves [32].
There are several limitations to this study. The first limitation is related to measurement issues for the outcomes; measurement and evaluation of the outcomes of pediatric cardiac surgery education programs are known to be difficult [32]. As a retrospective study without electronic medical records, the data were limited, and for some patients no information on outcomes was available. Follow-up visits also are limited as there are many barriers to accessing health care systems in LMICs. Therefore, we were not able to evaluate the post-operative patient outcomes in the long term. Hence, we focused on analysis of the process measures that were collected at the time of surgery, such as the complexity of cases and patient weights.
Furthermore, the qualitative data did not include all the Uzbek and Korean staff's experiences or perceptions of the program due to the time limit. The interviews with caregivers were conducted only once after the surgery due to the costs of tracking patients and patients' travel to the hospital [23]. Hence, accurate observation of changes in their quality of life before- and after intervention could not be explored.
Finally, this study was conducted with one surgical team in a single country. Therefore, the generalizability is limited, and the results should only be interpreted in the context of this study. While this case has limited generalizability, it can shed light on the planning and designing of other similar interventions.
Our program evaluation research has added to previous studies on the advantages of team-based training, in this case, for improving pediatric cardiac surgical care in LMICs. The findings revealed the program's multiple accomplishments and shortages, and areas for future improvement. The results of the current study will be applied to scale up the program in the future and to design a similar capacity-building program related to cardiac surgery in other developing-nation settings as well. While short-term, team-based training may not show immediate results, it can be an effective solution to increase and facilitate the local capacity for improving child health in relation to heart disease in LMICs.
We gratefully acknowledge the assistance of all research participants and colleagues involved in the pediatric cardiac surgery capacity-building training program in Uzbekistan.
Raphael Nanum Foundation; Noodle Lovers Company; Seoul National University Hospital, Public Health & Medical Service; and Seoul National University College of Medicine, JW LEE Center for Global Medicine funded the study.
The authors completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available upon request from the corresponding author) and declare no conflicts of interest.
Author Contribution
WK led program management and supervision of field data collection, and WK, JP and SC contributed to field data collection. SH and JH conceptualized and designed the study. SC and JH analyzed quantitative data while SH analyzed qualitative data. SH, SC, and JP wrote the initial draft. SH and SC were the major contributors in writing the manuscript. JH and WK provided critical comments. All authors provided revisions to the draft and approved the final manuscript.
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Cvetkovic M. Challenges in pediatric cardiac anesthesia in developing countries. Frontiers in Pediatrics. 2018; 6: 254. DOI: https://doi.org/10.3389/fped.2018.00254
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Kelly E, Doyle V, Weakliam D, Schönemann Y. A rapid evidence review on the effectiveness of institutional health partnerships. Globalization and Health. 2015; 11(1): 48. DOI: https://doi.org/10.1186/s12992-015-0133-9
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Trinchero E, Kominis G, Dudau A, Corduneanu R. With a little help from my friends: the positive contribution of teamwork to safety behaviour in public hospitals. Public Management Review. 2020; 22(1): 141–160. DOI: https://doi.org/10.1080/14719037.2019.1638443
Lingard L, Reznick R, Espin S, Regehr G, DeVito I. Team communications in the operating room: Talk patterns, sites of tension, and implications for novices. Academic Medicine. 2002; 77(3): 232–237. DOI: https://doi.org/10.1097/00001888-200203000-00013
Manser T. Teamwork and patient safety in dynamic domains of healthcare: A review of the literature. Acta Anaesthesiologica Scandinavica. 2009; 53(2): 143–151. DOI: https://doi.org/10.1111/j.1399-6576.2008.01717.x
Wiegmann DA, ElBardissi AW, Dearani JA, Daly RC, Sundt TM, III. Disruptions in surgical flow and their relationship to surgical errors: An exploratory investigation. Surgery. 2007; 142(5): 658–665. DOI: https://doi.org/10.1016/j.surg.2007.07.034
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Daftary A, Satyanarayana S, Jha N, et al. Can community pharmacists improve tuberculosis case finding? A mixed methods intervention study in India. BMJ Global Health. 2019; 4(3): e001417. DOI: https://doi.org/10.1136/bmjgh-2019-001417
Choi S, Vervoort D, Kim W-H. The role of cardiac surgery in global surgery and global health: A case study from Tashkent. Journal of Global Health Reports. 2019; 3. DOI: https://doi.org/10.29392/joghr.3.e2019074
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Salas E, Almeida SA, Salisbury M, et al. What are the critical success factors for team training in health care? The Joint Commission Journal on Quality and Patient Safety. 2009; 35(8): 398–405. DOI: https://doi.org/10.1016/S1553-7250(09)35056-4
Novick WM, Stidham GL, Karl TR, et al. Paediatric cardiac assistance in developing and transitional countries: the impact of a fourteen year effort. Cardiology in the Young. 2008; 18(3): 316–323. DOI: https://doi.org/10.1017/S104795110800?2175
Molloy FJ, Nguyen N, Mize M, et al. Medical missions for the provision of paediatric cardiac surgery in low- and middle-income countries. Cardiology in the Young. 2017; 27(S6): S47–S54. DOI: https://doi.org/10.1017/S104795111700261X
Dearani JA, Neirotti R, Kohnke EJ, et al. Improving pediatric cardiac surgical care in developing countries: Matching resources to needs. Seminars in Thoracic and Cardiovascular Surgery: Pediatric Cardiac Surgery Annual 2010. 2010; 13(1): 35–43. DOI: https://doi.org/10.1053/j.pcsu.2010.02.001
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Engelman D, Okello E, Beaton A, et al. Evaluation of computer-based training for health workers in echocardiography for RhD. Global Heart. 2017; 12(1): 17–23, e18. DOI: https://doi.org/10.1016/j.gheart.2015.12.001
Dearani JA, Jacobs JP, Bolman RM, III, et al. Humanitarian outreach in cardiothoracic surgery: From setup to sustainability. The Annals of Thoracic Surgery. 2016; 102(3): 1004–1011. DOI: https://doi.org/10.1016/j.athoracsur.2016.03.062
Welke KF, Jacobs JP, Jenkins KJ. Evaluation of quality of care for congenital heart disease. Seminars in Thoracic and Cardiovascular Surgery: Pediatric Cardiac Surgery Annual 2005. 2005; 8(1): 157–167. DOI: https://doi.org/10.1053/j.pcsu.2005.02.002
Han, S., Choi, S., Heo, J., Park, J. and Kim, W.-H., 2020. Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications. Annals of Global Health, 86(1), p.107. DOI: http://doi.org/10.5334/aogh.2883
Han S, Choi S, Heo J, Park J, Kim W-H. Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications. Annals of Global Health. 2020;86(1):107. DOI: http://doi.org/10.5334/aogh.2883
Han, S., Choi, S., Heo, J., Park, J., & Kim, W.-H. (2020). Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications. Annals of Global Health, 86(1), 107. DOI: http://doi.org/10.5334/aogh.2883
1. Han S, Choi S, Heo J, Park J, Kim W-H. Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications. Annals of Global Health. 2020;86(1):107. DOI: http://doi.org/10.5334/aogh.2883
Han S and others, 'Evaluation of a Ten-year Team-based Collaborative Capacity-building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications' (2020) 86 Annals of Global Health 107 DOI: http://doi.org/10.5334/aogh.2883
Han, Seungheon, Sugy Choi, Jongho Heo, Jayoung Park, and Woong-Han Kim. 2020. "Evaluation of a Ten-year Team-based Collaborative Capacity-building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications". Annals of Global Health 86 (1): 107. DOI: http://doi.org/10.5334/aogh.2883
Han, Seungheon, Sugy Choi, Jongho Heo, Jayoung Park, and Woong-Han Kim. "Evaluation of a Ten-year Team-based Collaborative Capacity-building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications". Annals of Global Health 86, no. 1 (2020): 107. DOI: http://doi.org/10.5334/aogh.2883
Han, S, et al.. "Evaluation of a Ten-Year Team-Based Collaborative Capacity-Building Program for Pediatric Cardiac Surgery in Uzbekistan: Lessons and Implications". Annals of Global Health, vol. 86, no. 1, 2020, p. 107. DOI: http://doi.org/10.5334/aogh.2883
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Division of HIV, Infectious Diseases and Global Medicine (ZSFG) - HS Clinical Assistant, Associate, or Full Professor (JPF04107)
Division of HIV, Infectious Diseases and Global Medicine (ZSFG) - HS Clinical Assistant, Associate, or Full Professor
Apply now to Division of HIV, Infectious Diseases and Global Medicine (ZSFG) - HS Clinical Assistant, Associate, or Full Professor
Medicine / SCHOOL OF MEDICINE / UC San Francisco
Open date: August 29, 2022
Most recent review date: Thursday, Oct 27, 2022 at 11:59pm (Pacific Time)
Final date: Thursday, Feb 29, 2024 at 11:59pm (Pacific Time)
The Department of Medicine, Division of HIV, Infectious Diseases and Global Medicine at Zuckerberg San Francisco General Hospital (ZSFG) is seeking a clinical faculty member for a full-time faculty position. The selected candidate will be appointed at the level of Assistant, Associate, or Full Professor in the HS Clinical series depending on qualifications and interests.
Faculty in the Health Sciences Clinical Professor series are salaried appointees in the health sciences who teach, participate in patient care, and may participate in University and/or public service and scholarly and/or creative activities. Faculty in this series teach the application of basic sciences and the mastery of clinical procedures in all areas concerned with the care of patients. The new faculty member will play key roles in the HIV, Infectious Diseases and Global Medicine Division's pandemic response clinical care enterprise, providing inpatient, outpatient, and telemedicine COVID-19 care and consultative services. In addition, the new faculty member will become an integral member of the ZSFG infectious diseases clinic team and provide direct clinical services and consultation on novel emerging pandemic threats. Finally, the new faculty member will join the Division's AIDS Clinical Trials Group (ACTG) clinical trials team, providing direct clinical work within ongoing HIV and infectious diseases research studies. The faculty member will supervise and teach residents, fellows, and medical students in Infectious Diseases.
• MD and board certified in Internal Medicine by the ABIM.
• Demonstrates excellent communication skills.
• Demonstrates ability to document clinical encounters accurately and in a timely manner.
• Familiarity with COVID-19 management principles and infection control principles.
• Board eligible or board certified in infectious diseases by ABIM.
• Proficiency with Epic Systems software.
• Spanish language proficiency.
Please apply online at https://aprecruit.ucsf.edu/JPF04107 with CV, cover letter, statement of contributions to diversity, and the contact information for three references. Applicants' materials must list current and/or pending qualifications upon submission. To receive full consideration, please submit all materials prior to the initial review date. However, this position will remain open until filled.
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The adipocyte-derived hormone leptin plays a critical role as a metabolic cue for the reproductive system. Conditions of low leptin levels observed in negative energy balance and loss-of-function mutations of leptin or leptin receptor genes are characterized by decreased fertility. In recent years, advances have been made for identifying possible hypothalamic neurons relaying leptin's neuroendocrine control of reproductive function. Studies from different laboratories have demonstrated that leptin action in the hypothalamo-pituitary-gonadal (HPG) axis is exerted via hypothalamic interneurons regulating gonadotropin-releasing hormone (GnRH) cells, oppose to direct action on GnRH neurons. Following this observation, studies focused on identifying leptin responsive interneurons. Using a Cre-loxP system to re-express or delete the leptin receptor long form (LepRb) from kisspeptin neurons, our laboratory found that leptin's action on kiss1 cells is neither required nor sufficient for leptin's role in reproductive function. Endogenous re-expression of LepRb however, in glutamatergic neurons of the ventral premammilary nucleus (PMV) or ablation of agouti-related protein (AgRP) neurons from leptin signaling-deficient mice are both sufficient to induce puberty and improve fertility. Recent studies have also shown that leptin action in first order GABAergic neurons is required for fertility. Together, these studies begin to delineate key neuronal populations involved in leptin's action in reproduction. In this review, we discuss recent advances made in the field and highlight the questions yet to be answered.
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Hospice is only for Cancer patients?
Thanks to the education efforts of hospice programs across the country, the national percentage of non malignant hospice admissions has risen. However many consumers are not aware of this and more education is needed, especially by the medical community. Patients and their families need to know that while hospice programs have their own admission criteria; Infinity Hospice Care is non-discriminatory even in end stage diagnosis.
Hospice is only for people that are close to death or actively dying?
Do I have to give up my primary care physician?
Infinity Hospice Care encourages the primary physician to be part of the Interdisciplinary Care Team and continue to see the patient. We supplement rather than replace the primary physician and will even provide transportation to the physician's office for patients who are otherwise unable to get there.
Does hospice take the place of my family or caregiver?
No, hospice cares for the family as well as the patient by providing emotional and spiritual support to ensure quality of life for everyone involved in the care.
Will hospice take the place of my family?
With a true managed focus, the Interdisciplinary Team involves the family in the plan of care and provides support and assistance to the family. Hospice helps to "mend fences" and attempts to reunite family members in as much as they are able. We are there to support the family system in the care of the patient.
Is my doctor the only one who can make the Hospice referral?
The fact is that anyone can make a hospice referral. An educated consumer is more aware of choices about health care and can ask for information at any time about health care and can ask for information at any time about hospice services. The hospice personnel will contact the physician's office to ascertain medical information and to determine appropriateness of care and obtain orders.
Aren't all hospice programs alike?
While it is true that all Medicare Certified Hospice Programs follow the same rules to earn their certification, there can be significant differences in admission criteria and follow up care options. At Infinity Hospice Care we are completely non-discriminatory in disease process; approve of certain palliative treatment options; include the primary physician in our plan of care; and seek to raise the standard of hospice care throughout our service area.
I am on a fixed income and with all the services offered, hospice care must be expensive?
Hospice care is covered 100% by Medicare. Most private insurances have added some form of coverage for palliative end-of-life care. Unlike home health, whose services generally decrease over time, hospice care increases as the patient's condition warrants additional care. This support helps to alleviate the frequent need for unnecessary hospitalizations which tend to escalate in the last year of life.
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Orthodontic Therapy and the Airway – An AAO White Paper Review (Part 2)
By Jeffrey Rouse on January 6, 2021 | comments Print
Editor's note: This is the second of two articles from Dr. Jeff Rouse's review of the 2019 American Association of Orthodontists (AAO) White Paper – Obstructive Sleep Apnea and Orthodontics. The paper was the culmination of a two-year project by a panel of sleep medicine and dental sleep experts tasked to produce guidelines for the role of orthodontists in the management of obstructive sleep apnea (OSA). In Part 1, Dr. Rouse wrote on the potential impacts of tooth extraction on the airway. Here he examines the paper's guidance for adult and childhood management of obstructive sleep apnea (OSA) by orthodontists.
Author's note: The topic of the impact of tooth extraction on the airway can be very contentious. My hope is these articles serve as a tool to allow collegial discourse between restorative dentists concerned with airway and the orthodontists who they look to for solutions.
In the airway prosthodontic curricula at Spear, the focus is – Just Do Dentistry. The concept builds on the foundation of Facially Generated Treatment Planning (FGTP). In FGTP, complex treatment planning begins by setting the incisal edges of the maxillary central incisors as you would in a denture. The addition of airway reminds us that we never set the teeth in a denture until the anteroposterior (AP) and transverse dimension of the wax rim are ideal. The AP and transverse dimensions have come to represent the airway.
We would never set teeth to a deficient wax rim. Yet, restorative dentists and orthodontists commonly work within and/or camouflage maxillary hypoplasia. This critical difference between treating OSA and "Just Doing Dentistry" can be found in the 2019 AAO White Paper – Obstructive Sleep Apnea and Orthodontics.
In the paper's sixth section, "Orthodontic Management in Adult OSA," the task force focused extensively on orthodontists fabricating mandibular advancement appliances in concert with sleep physicians. Informed consent, appliance titration, and occlusal alteration were reviewed.
At Spear, we would classify this as sleep dentistry rather than airway focusing on augmenting the oral anatomy with a piece of plastic with the express goal of improving breathing during sleep. If the appliance is not worn or when the appliance is removed, the patient's airway has not been improved. The AAO does conclude with a look at resolving the issue instead it suggests:
"Maxillomandibular advancement (MMA) generally is reserved for patients with severe OSA who are unable to tolerate PAP... and/or oral appliance therapy..., and for those patients who also have an orthodontic indication for the procedure."
In my opinion, this sentence is backwards. MMA is designed and reserved for patients who have a skeletal requirement for the procedure. FGTP has focused on that for years but, in my office, has failed to deliver on MMA for esthetic and functional reasons.
Severe apnea patients who failed positive airway pressure (PAP) or oral appliance therapy have a greater incentive for care. The idea you should wait until the disease is severe before considering treatment is counterproductive and counterintuitive. Waiting for patients to become extremely ill before you treat their skeletal issues makes surgery less apt to cure or significantly reduce OSA and the healing more problematic, as bone and tissue are negatively affected by long-term OSA.
The vast majority of OSA patients have a skeletal component – retrognathic maxilla, mandible, or both. The "Just Do Dentistry" concept suggests the "orthodontic indication" should be the focus rather than the apnea. In that case, we tell the patient we are going to resolve the skeletal issues impacting their esthetics and function. We then follow the AAO guideline:
"Improvement of the OSA should be highlighted as a 'possible,' or some studies say 'anticipated,' outcome of treatment. But no guarantees of OSA resolution can be implied or stated emphatically by the treating orthodontist."
The advantage of focusing on the dentistry is that skeletal issues are addressed at an earlier age. Patients do not have to have severe OSA and fail PAP or oral appliance therapy to justify the treatment. Also, the patient doesn't have to go through a litany of "less invasive" options that make MMA results worse. It is my opinion; we should put the skeleton in its optimal position and provide the patient with the best chance to heal as early as possible.
Two additional procedures to alter the maxilla were discussed in the guidelines – surgically assisted rapid maxillary expansion (SARME) and mini‐implant supported rapid maxillary expansion (MARME).
If the maxilla is deficient, there are OSA patient studies that suggest an improvement in sleep parameters are possible with an improvement in nasal volume and flow. These procedures are gaining in popularity and new research published since the AAO review continues to show their positive effects for patients with all levels of apnea and much less invasive surgical techniques.
Pediatric OSA
The pediatric section of the white paper can be summarized in the following statement: The orthodontic treatment plan for patients with OSA should follow the same orthodontic principles for correction of dental and skeletal deformities. In other words, "Just Do Dentistry."
I have two comments:
Patients with OSA implies they have had a sleep study. Previous Spear articles have discussed the issues with pediatric sleep studies and the fact that most treatment can be done based on symptoms and not sleep study numbers. Additionally, if you wait for an OSA diagnosis before treating children, you are waiting for disease and will miss most of the patients who could benefit from the intervention.
The only so-called principle that should change is the timing of therapy. The AAO has recommended the first orthodontic evaluation should be done at seven years old. Historically, the orthopedic expansion would begin after the eruption of the first molars. Today, if skeletal deformities are present, fix them when you find them.
Jeffrey Rouse, D.D.S., is a member of Spear Resident Faculty.
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Airway Aware: The Next Step in Treatment Planning
By Jeffrey Rouse 1 month ago
A-EFSB: Airway and 3D Treatment Planning
By Jeffrey Rouse 1 year ago
Etiologies of Wear
Wear Patterns in Diagnosis
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Our Nuclear Medicine & PET/CT Center offers a wide variety of scintigraphy procedures to evaluate and diagnose several areas of the body.
This technique requires a radioactive material to be administered intravenously or by ingestion, after which specialized cameras detect the radiation emitted and capture detailed two-dimensional images of the area or system in question.This safe and reliable technique is an integral tool in proper detection and diagnosis by the VM-Med team.
Our highly qualified physicians and support staff provide courteous, personalized service to all our patients and strive to deliver accurate results in the shortest possible time. Appointments can be booked with little wait time, and patients can expect to be seen within 48 hours of booking, in some cases on the same day.
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by Dr. Jeremy Smith, O.D.
Some eye conditions arise with few or no symptoms noticeable in day-to-day life. A brief annual exam checks for changes to vision and for the presence of any symptoms of eye diseases. The exam can catch potential issues before they become problematic or even untreatable, making it a critical part of maintaining your overall health and well-being.
An ophthalmologist, optometrist or orthoptist is qualified to conduct your eye exam, and you can get that exam at a variety of locations.
1) An oral questionnaire inquires after noted changes to vision or health.
2) Visual acuity is measured by asking a patient to read letters on a Snellen chart. This test is often a first indicator that patients require corrective lenses or that their prescription for corrective lenses needs to be updated.
3) Retinoscopy and refraction assessment refine a patient's prescription by having her compare vision while clicking through a series of lenses.
is checked by tracking the behavior of the pupil in response to light. This tests how the individual pupil responds to light, and it ensures that both pupils respond to light in tandem.
5) Extraocular muscle motility is demonstrated by having the patient follow the motion of an object with his eyes. This ensures that the muscles related to eye movement, and the parts of the brain controlling those muscles, are functioning correctly.
6) Perimetry tests measure the patient's visual field and peripheral vision. Loss of peripheral vision is often an early sign of glaucoma.
7) Ophthalmoscopy checks the health of the retina by dilating the pupil with special drops and viewing the back of the eye with a special light. This helps detect conditions such as retinal detachment, optic nerve swelling, damaged blood vessels in the retina from high blood pressure or diabetes, cataracts and other problems.
8) Colorblindness testing includes an Ishihara exam where a patient reviews images to confirm the ability to differentiate between different colors.
9) Tonometer testing checks for increased intraocular pressure, a symptom of glaucoma. Once the eye has been numbed, an applanation tonometer machine barely touches the surface of the eye and measures the pressure of the fluid within the eye.
Ask your primary medical care provider to recommend a qualified eye care professional for your annual exam. You can also use the American Optometric Association's locator tool to find an optometrist in your area.
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If you have received a letter telling you that your smear was abnormal, you will be understandably anxious and a bit worried. However, an abnormal smear almost always means that a minor problem (pre-cancerous change) has been detected and not anything serious (such as cervical cancer). It means that your smear test has done its job and this minor problem can now be dealt with. It is very common to have an abnormal smear (one in twelve smears are not normal), but it is extremely rare for this abnormality to be cancer.
The smear abnormality can be mild, moderate or severe. Medical term used for describing an abnormal smear is dyskaryosis. Even when the smear shows severe dyskaryosis, it usually occurs 5-10 years before cervical cancer. Borderline grade is between normal and mild, so it means almost normal but not quite. Low grade smears (mild and borderline) will very often revert back to normal without any treatment; whereas, high grade smears (moderate and severe) often need to be treated. A colposcopy examination will often be recommended for any grade of abnormality.
Abnormal smears often represent a pre-cancerous abnormality on the cervix. These pre-cancerous abnormalities are caused by Human Papilloma Virus (HPV or Wart virus). This is a very common infection and 60-70% women (and men) get it at some stage in life. Most (95%) women will shake it off through their immunity, but in some women it may linger on and cause abnormal smears. More information on HPV can be found by clicking here.
With low grade changes (mild dyskaryosis and borderline changes), either you will be advised to have a repeat smear or you may be referred to a gynaecologist for a special investigation called colposcopy. If the changes are confirmed to be mild on colposcopy, usually a conservative approach is followed as there is a good chance of spontaneous resolution. You must however make sure that you attend for follow-up as directed by your GP or gynaecologist. With high grade changes (moderate and severe dyskaryosis), you will be referred to a gynaecologist for colposcopy and possible treatment. If these changes are not treated, they carry a risk of progression to cancer over 5-10 years.
Colposcopy is a simple office procedure and as an experience is very similar to having a smear test done. Cervix is visualised using a speculum and it is examined under magnification for evidence of low/high grade changes. Two dyes are applied to the cervix (acetic acid and iodine) which highlight the abnormality if present. Colposcopy examination is carried out by a specialist gynaecologist who is accredited by the British Society of Colposcopy and Cervical Pathology (BSCCP). A nurse will also be present and you will be given an option to see your cervix on the screen.
The commonest form of treatment is LLETZ (Large Loop Excision of Transformation Zone). It is also known as LEEP (Loop Electrosurgical Excision Procedure, an American term). This is commonly carried out as an office procedure under local anaesthesia. After numbing the cervix with local anaesthetic, a wire loop is used to remove the abnormal cells. It is a quick and easy procedure and there is some discomfort, but no sharp pain.
We offer colposcopy packages for self pay patients and a specialist website, London Colposcopy with more information on abnormal smear management and colposcopy.
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Treatments for atopic eczema articles.
There are many varieties of ointments and creams and medications to help treat a case of severe eczema, but it can be a complicated matter when, in the case of atopic dermatitis or eczema, your skin disorder can be linked to allergic reactions such as asthma and hay fever. Atopic eczema affects both children and adults, and is usually revealed in early childhood, sometimes before the age of one year. In these cases, it usually has its' roots in family members' medical histories, and can persist through to another child or sibling in the same family.
One of the most common symptoms in any case of eczema is pruritis, or intense itchiness, that then turns into a rash that varies from redness to inflammation and cracking. In the case of cracking, the dermis begins to develop sores from the severity of scratching those spots where it develops consistently, and can even begin to weep or become a case of wet eczema. Constant scratching of an area will leave prone to infection while fluid tends to leak from these wounds, and when the skin splits like this, an emollient may be used to help rehydrate the skin while a topical steroid will reduce the inflammation.
The affected spots will usually look red when the eczema is flaring up, but lumps and/or blisters can also appear in the affected areas, which usually foreshadows a bout with cracking and scaling skin soon afterwards without proper treatment of this atopic skin disorder. After an episodic flare-up, the area can tone down to a lesser degree of active affliction, but the area can always become active under the most distressful circumstances. Treatments do not have to be as problematic as the ailment itself, and even simple steps; like avoiding certain types of soaps and detergents, can be helpful in discouraging flare-ups. Even irritating fabrics can be the source of a particular flare-up, and should be avoided as well.
Moisturizers can help greatly in the day-to-day habits to rehydrate particular areas where eczema can commonly appear, as dry skin tends to flare-up into inflammation, but this can be eliminated with the proper moisturizing regiment. Prevention through keeping your skin supple and moist can alleviate these symptoms of dryness, but can be tedious and difficult work to manage, though particularly well worth it. If inflammation consistently flares up, a topical steroid may be prescribed by a practicing physician or licensed dermatologist, and the inflammation should be prevented when spread over the afflicted areas sparingly, and always use the lowest strength that works well for you.
With moisturizers, the emollient works by replacing the body oils that can get washed away by using soap and water that tends to dry out skin, and keeps a layer of substituted oil on the skin. The more greasy or thick the moisturizer is the better it will work, but the less pleasant they will be to use. With application being liberal to all parts of affected skin, and it is always wise to use topical steroids and moisturizers in conjunction with one another, though the steroid would definitely go on first ads opposed to the emollient.
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Muscle wasting is common when a patient is immobilized from illness or injury. With the muscles not stimulated by normal activities and load, catabolic (tissue deconstructive) processes dominate. This may result in a significant loss of muscle protein, which is both rapid and pronounced. In some cases this can turn into a serious added complication, interfering with the individual's recovery and mobility. Over there years, many strategies have been devised and implemented to counter muscle wasting. However, and oddly so in spite of their known tissue building and preserving properties, anabolic steroids are not widely used for this purpose. Studies continue to investigate such applications though, suggesting we may see such medical applications open up again. One such paper was recently published in PlosOne, finding notable benefit with nandrolone decanoate (1).
[nandrolone decanoate] preserves protein content and muscle weight, which may result advantageous to the affected skeletal muscle for functional recovery." While I suspect that we are far from a day that nandrolone would be considered a standard treatment option for such cases, it is good to see research in this area continue, and felt it good to pass along.
The summary here pertains to the most obvious finding of the study. There is much more to the paper, which is actually an extensive investigation into not only the obvious effects of nandrolone decanoate on muscle disuse atrophy, but also the underlying mechanisms involved. A link to the full article is below for those interested in studying the deeper science of AAS biochemistry and muscle atrophy. It is definitely worth a read.
(1) Effects of Nandrolone in the Counteraction of Skeletal Muscle Atrophy in a Mouse Model of Muscle Disuse: Molecular Biology and Functional Evaluation. Camerino GM, Desaphy JF, De Bellis M, Capogrosso RF, Cozzoli A, Dinardo MM, Caloiero R, Musaraj K, Fonzino A, Conte E, Jagerschmidt C, Namour F, Liantonio A, De Luca A, Conte Camerino D, Pierno S. PLoS One. 2015 Jun 11;10(6):e0129686. doi: 10.1371/journal.pone.0129686.
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Browsing M.Sc. Applied Health Sciences by Title
Brock Theses
M.Sc. Applied Health Sciences
3D movement and muscle activity patterns in a violin bowing task
Wales, Jennifer.; Applied Health Sciences Program (Brock University, 2007-06-29)
Objective: Overuse injuries in violinists are a problem that has been primarily analyzed through the use of questionnaires. Simultaneous 3D motion analysis and EMG to measure muscle activity has been suggested as a quantitative technique to explore this problem by identifying movement patterns and muscular demands which may predispose violinists to overuse injuries. This multi-disciplinary analysis technique has, so far, had limited use in the music world. The purpose of this study was to use it to characterize the demands of a violin bowing task. Subjects: Twelve injury-free violinists volunteered for the study. The subjects were assigned to a novice or expert group based on playing experience, as determined by questionnaire. Design and Settings: Muscle activity and movement patterns were assessed while violinists played five bowing cycles (one bowing cycle = one down-bow + one up-bow) on each string (G, D, A, E), at a pulse of 4 beats per bow and 100 beats per minute. Measurements: An upper extremity model created using coordinate data from markers placed on the right acromion process, lateral epicondyle of the humerus and ulnar styloid was used to determine minimum and maximum joint angles, ranges of motion (ROM) and angular velocities at the shoulder and elbow of the bowing arm. Muscle activity in right anterior deltoid, biceps brachii and triceps brachii was assessed during maximal voluntary contractions (MVC) and during the playing task. Data were analysed for significant differences across the strings and between experience groups. Results: Elbow flexion/extension ROM was similar across strings for both groups. Shoulder flexion/extension ROM increaslarger for the experts. Angular velocity changes mirrored changes in ROM. Deltoid was the most active of the muscles assessed (20% MVC) and displayed a pattern of constant activation to maintain shoulder abduction. Biceps and triceps were less active (4 - 12% MVC) and showed a more periodic 'on and off pattern. Novices' muscle activity was higher in all cases. Experts' muscle activity showed a consistent pattern across strings, whereas the novices were more irregular. The agonist-antagonist roles of biceps and triceps during the bowing motion were clearly defined in the expert group, but not as apparent in the novice group. Conclusions: Bowing movement appears to be controlled by the shoulder rather than the elbow as shoulder ROM changed across strings while elbow ROM remained the same. Shoulder injuries are probably due to repetition as the muscle activity required for the movement is small. Experts require a smaller amount of muscle activity to perform the movement, possibly due to more efficient muscle activation patterns as a result of practice. This quantitative multidisciplinary approach to analysing violinists' movements can contribute to fuller understanding of both playing demands and injury mechanisms .
Active isolated stretching : an investigation of the mechanical mechanisms
Longo, Alison.; Applied Health Sciences Program (Brock University, 2009-02-16)
The Active Isolated Stretching (AIS) technique proposes that by contracting a muscle (agonist) the opposite muscle (antagonist) will relax through reciprocal inhibition and lengthen without increasing muscle tension (Mattes, 2000). The clinical effectiveness of AIS has been reported but its mechanism of action has not been investigated at the tissue level. Proposed mechanisms for increased range of motion (ROM) include mechanical or neural changes, or an increased stretch tolerance. The purpose of the study was to investigate changes in mechanical properties, i.e. stiffness, of skeletal muscle in response to acute and long-term AIS stretching for the hamstring muscle group. Recreationally active university-aged students (female n=8, male n=2) classified as having tight hamstrings, by a knee extension test, volunteered for the study. All stretch procedures were performed on the right leg, with the left leg serving as a control. Each subject was assessed twice: at an initial session and after completing a 6-week AIS hamstring stretch training program. For both test sessions active knee extension (ROM) to a position of "light irritation", passive resisted torque and stiffness were determined before and after completion of the AIS technique (2x10 reps). Data were collected using a Biodex System 3 Pro (Biodex Medical Systems, NY, USA) isokinetic dynamometer. Surface electromyography (EMG) was used to monitor vastus lateralis (VL) and hamstring muscle activity during the stretching movements. Between test sessions, 2x10 reps of the AIS bent knee hamstring stretch were performed daily for 6-weeks.
THE ACUTE EFFECTS OF A SINGLE SESSION OF PLYOMETRIC EXERCISE ON MARKERS OF BONE TURNOVER IN BOYS AND MEN
Kish, Kimberly; Applied Health Sciences Program (Brock University, 2014-03-07)
The study objective was to compare the response of bone markers to an exercise session consisting of high mechanical loading (144 jumps) between boys (n=12, 10.2 ± 0.4 years) and men (n=18, 22.5 ± 0.7 years). Blood samples were collected at pre-, 5, 60 minutes post-, and 24 hours post-exercise) to measure bone-specific alkaline phosphatase (BAP), amino-terminal cross-linking telopeptide (NTx), osteoprotegrin (OPG) and receptor activator of nuclear factor kb ligand (RANKL). Boys had higher BAP levels at all time points, with an increase 24 hours post-exercise. No such increase was observed in men. Likewise, NTx levels were higher in boys, with a greater increase over time than in men. OPG and RANKL levels were similar in boys and men at all times. In summary, even one session of exercise stimulates bone turnover, as reflected in the increase in both BAP and NTx, in boys (but not men) within 24 hours.
The acute effects of differential dietary fatty acids on PDHa activity in human skeletal muscle at the onset of exercise
Bradley, Nicolette Shannon.; Applied Health Sciences Program (Brock University, 2006-06-29)
Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise and its activity can be down-regulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of PDH in its active form (PDHa) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n=7) underwent 2 fat loading trials spaced at least 2 weeks apart. Subjects consumed saturated (SFA) or polyunsaturated (PUFA) fat over the course of 5 hours. Following this, participants cycled at 65% VO2 max for 15 min. Muscle biopsies were taken prior to and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 ± 0.07 to 0.54 ± 0.19 mM over 5 hours with SFA and from 0.1 1 ± 0.04 to 0.35 ±0.13 mM with PUFA. PDHa activity was unchanged following fat loading, but increased at the onset of exercise in the SFA trial, from 1 .4 ± 0.4 to 2.2 ± 0.4 /xmol/min/kg wet wt. This effect was negated in the PUFA trial (1 .2 ± 0.3 to 1 .3 ± 0.3 pimol/min/kg wet wt.). PDH kinase (PDK) was unchanged in both trials, suggesting that the attenuation of PDHa activity with PUFA was a result of changes in the concentrations of intramitochondrial effectors, more specifically intramitochondrial NADH or Ca^*. Our findings suggest that attenuated PDHa activity participates in the preferential oxidation of PUFA during moderateintensity exercise.
The acute effects of systemic cytokines on peripheral nerve function in humans
Allison, David; Applied Health Sciences Program (Brock University, 2011-10-24)
Cytokines have been shown to cause a reduction in nerve conduction when examined using animal models. Such effects, if shown in humans, could result in detrimental effects to physical function during periods heightened systemic cytokine concentrations. The study investigated the acute effects of cytokines on nerve conduction velocity (NCV) and functional measures. Measures were taken under both basal and elevated cytokine concentrations to determine any corresponding changes to NCV. A significant positive correlation was found between the cytokine IL-6 and NCV at 2 hours post-exercise (r=0.606, p=0.048). A significant negative correlation was found between IL-1ra and NCV at 24 hours post-exercise (r=-0.652, p=0.021). A significant positive correlation was also found between IL-1ra and endurance at 1 hour post-exercise (r=0.643, p=0.033). As such, it would seem that IL-6 may potentially act to enhance nerve function while other cytokines such as IL-1ra may have negative effects and reduce NCV.
Acute endocrine responses to plyometrics versus resistance exercise in children
Giannopoulou, Angeliki; Applied Health Sciences Program
The purpose of this study was to examine the acute hormonal responses to a bout of resistance versus plyometric exercise in young male athletes. Specifically, changes in salivary cortisol, testosterone and testosterone-to-cortisol ratio from pre- to post-exercise between the two different exercise protocols were examined. Twenty-six peri-pubertal active boys participated in this cross-over study, completing two exercise sessions. During each session, participants first completed a 30 min control period, which did not include any exercise, and then was randomly assigned to perform a 45 min of either a resistance exercise or a plyometric exercise protocol. All participants crossed over to perform the other exercise protocol during their second exercise session, a week later. Four saliva samples during each protocol were taken at: baseline, pre-exercise, 5 min post-exercise and 30 min post-exercise. Significant increases in testosterone values were reported 5 min post-exercise following the resistance protocol, but not the plyometric protocol. Both exercise protocols resulted in significant cortisol decreases overtime, as well as significant testosterone-to-cortisol ratio increases. The post-exercise increases in salivary testosterone and testosterone-to-cortisol ratio followed the typical exercise induced anabolic response seen in adults. However, the post-exercise decrease in salivary cortisol was different than the typical adult response indicating an insufficient stimulus for this age group maybe due to their stage of the biological development. Thus, in the adolescent boys, exercise appears to change the anabolic to catabolic balance in favor of anabolism.
Adaptations of skeletal muscle pyruvate dehydrogenase kinase in response to food-restriction in mitochondrial subpopulations
MacPherson, Laura Lynn.; Applied Health Sciences Program (Brock University, 2007-06-09)
University, 2006 Dr. Sandra J. Peters Pyruvate dehydrogenase (PDH) catalyses the decarboxylation of pyruvate, to form acetyl-CoA. PDH activity is down-regulated by intrinsic PDH kinases (predominantly PDK2 and PDK4 isoforms), but the understanding of the PDK isoform distribution and adaptation to nutritional stresses has been restricted to mixed mitochondrial populations, and not delineated between subsarcolemmal (SS) and intermyofibrillar (IMF) subpopulations. SS and IMF mitochondria exhibit distinct morphological and biochemical properties; however the functional differences are not well understood. This study investigated the effect of fed (FED) versus 48 h total foodrestriction (FR) on rat red gastrocnemius muscle PDK2 and 4 isoform content in SS and IMF mitochondria. PDK4 content was ~3-5 fold higher in SS mitochondria compared to IMF (p=0.001), and increased with FR -3-4- fold in both subpopulations (p<0.001). PDK2 was -2.5-4 fold higher in SS mitochondria compared to IMF (p=0.001), but PDK2 was unaltered with FR. Citrate synthase activity (|imol/min/mg mitochondrial protein) was not different between either subpopulation. As well there were no significant differences between mitochondrial subpopulations in PDH complex components in both fed and FR states. These results demonstrate that there is a markedly higher content of both PDK isofonns in SS compared to IMF mitochondria. Although PDK2 does not increase in either subpopulation in response to FR, PDK4 increases to a similar extent in both SS and IMF after 48 h food-restriction.
Anaerobic performance in ice hockey : the effect of skate blade radius of hollow
Winchester, Andrew.; Applied Health Sciences Program (Brock University, 2007-06-29)
The purpose of the study was to investigate the effect of skate blade radius of hollow (ROH) on anaerobic performance, specifically during the acceleration and stopping phases of an on-ice skating test. Fifteen, male Junior B hockey players (mean age 19 y ± 1.46) were recruited to participate. On-icc testing required each participant to complete an on-ice anaerobic performance test [Reed Repeat Skate (RRS)) on three separate days. During each on-ice test, the participant's skate blades were sharpened to one of three, randomly assigned, ROH values (0.63 cm, 1.27 cm, 1.90 cm). Performance times were recorded during each RRS and used to calculate anaerobic variables [anaerobic power (W), anaerobic capacity (W), and fatigue index (s, %)). Each RRS was video recorded for the purpose of motion analysis. Video footage was imported into Peak Motus™ to measure kinematic variables of the acceleration and stopping phases. The specific variables calculated from the acceleration phase were: average velocity over 6 m (m/s), average stride length (m), and mean stride rate (strides/s). The specific variables calculated from the stopping phase were: velocity at initiation of stopping (rn/s), stopping distance (m), stopping time (s). A repeated measures ANOV A was used to assess differences in mean performance and kinematic variables across the three selected hollows. Further analysis was conducted to assess differences in trial by trial performance and kinematic variables for all hollows. The primary findings of the study suggested that skate blade ROH can have a significant effect on kinematic variables, namely stride length and stride rate during the acceleration phase and stopping distance and stopping time during the stopping phase of an on-ice anaerobic performance test. During the acceleration phase, no significant difdifferences were found in SR and SL across the three selected hollows. Mean SR on the 1.27 cm hollow was significantly slower than both the 0.63 cm and 1.90 cm hollows and SL was significantly longer when skating on the 1.27 cm hollow in comparison to the 1.90 cm hollow. During the stopping phase, stopping distance on the 0.63 cm hollow (4.12 m ± 0.14) was significantly shorter than both the 1.27 cm hollow (4.43 m ± 0.08) (p < 0.05) and the 1.90 cm ho])ow (4.35 m ± 0.12) (p < 0.05). Mean ST was also significantly shorter when stopping on the 0.63 cm hollow then both the 1.27 cm and 1.90 cm hollows. Trial by trial results clearly illustrated the affect of fatigue on kinematic variables; AV, SR, IV decreased from trial 1 to 6. There was no significant effect on anaerobic performance variables during the RRS. Altering the skate blade ROH has a significant and practical affect on accelerating and stopping performance will be discussed in this paper.
An analysis of students' travel motivations and images of China as a tourist destination
Chen, Xu.; Applied Health Sciences Program (Brock University, 2004-07-14)
Despite China's rapid growth in inbound tourism, the nature of its Canadian tourist market has been insufficiently studied. In response to this need, the objectives of this study are to identify China's destination image in Canadian students' minds, their possible internal motivations for visiting China as well as examining demographic influences on people's destination image formation. The study reviews image formation process and travel motivation categorisation, discusses their relationship, and implements Baloglu and McCleary's (1999) perceptual and affective image formation model and "push and pull factors" theory as its framework. A self-administered survey was applied to 424 undergraduate students in a Canadian university in early 2004. Exploratory factor analyses were conducted to identify perceived images and travel motivation. Summated means were calculated to illustrate the affective attitudes. A series of f-test and ANOVA tests were employed to examine the influence of demographics. An open-ended question format was adopted to analyse other images, motivations and visitation barriers that students may have. Findings demonstrate that cultural and natural attractions are the predominant image which the Canadian students have of China'; some stereotypes and negative images still influence the students' perception; travel service quality is largely unknown; increasing knowledge and seeking excitement and fun are the significant motivators in the likelihood of the Canadian students choosing to visit China; and personal interests may be a factor that significantly influences an individual's destination image and travel motivation. Raising awareness and increasing familiarity through promotion are suggested as methods to create a positive destination image of China.
Arterial Stiffness In Children With And Without Developmental Coordination Disorder
Philips, Nicole; Applied Health Sciences Program (Brock University, 2014-09-04)
The purpose of this study was to determine whether children with potential developmental coordination disorder (p-DCD) demonstrate increased arterial stiffness and thickness compared to age and school matched controls (mean age 14.7 yrs). We also assessed whether these measures differed by sex. Compliance, distensibility, and intima-media thickness (IMT) were measured at the common carotid artery for 28 children with p-DCD and 47 controls. ECG-R-wave-toe pulse wave velocity (PWV) was also measured for 29 children with p-DCD and 45 controls. We found that compared to controls males with p-DCD had significantly higher PWV (3.8±0.2 vs. 4.1±0.3, p=0.001) and lower distensibility (0.82± 0.19 vs. 0.70± 0.17, p=0.034) while females showed no significant differences (p=0.523 and p=0.123 respectively). As a result, it is apparent that sex differences exist with respect to arterial health within this population and that children with p-DCD may be more likely to develop cardiovascular disease later in life.
Assessment of the effects of rosemary extract on mast cell-mediated allergic inflammation
Yousef, Michael; Applied Health Sciences Program
The prevalence of allergic inflammatory disorders is increasing at an alarming rate, with 40-50% of school-aged children suffering today. Mast cells are immune sentinels and a driving force in both normal and pathological contexts of inflammation. Crosslinking of FcεRI by allergen-bound IgE antibodies leads to mast cell degranulation resulting in an early phase response, and the release of newly synthesized pro-inflammatory mediators, contributing to a late phase response. The mitogen-activated protein kinase (MAPK) family, phosphoinositide 3-kinase/protein kinase B (PI3K-Akt), and nuclear factor-κ-light-chain-enhancer of activated B cells (NF-κB) pathways have been established to be driving mechanisms behind mast cell-induced inflammation. Rosemary extract (RE) is rich in polyphenols and has been shown to inhibit the MAPK, PI3K-Akt, and NF-κB pathways in other cellular contexts in vitro and in in vivo. However, the effect of RE on mast cell activation has not been explored. Therefore, the aim of this study was to evaluate RE in modulating mast cell activation and FcεRI signaling via these pathways toward understanding the mechanism of action and functional outcomes. Mast cells were sensitized with anti-TNP IgE and were stimulated with the cognate allergen (TNP-BSA) under stem cell factor (SCF) potentiation and treated with 0 – 25 µg/ml RE. Samples were then collected for western blot analysis, quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), β-hexosaminidase assay, and NFкB transcription factor activity assay. Western blot analysis demonstrated that RE treatment at both 5 and 25 µg/ml inhibited phosphorylation of p38-MAPK, and treatment with 25 µg/ml inhibited JNK. qPCR analysis showed that RE treatment at 25 µg/mL resulted in decreased gene expression of IL6, TNF, IL13, CCL1, and CCL3. It also reduced Rcan1, and NFкBIA mRNA levels. ELISA analysis further supported the qPCR data showing decreases in pro-inflammatory IL-6, TNF, IL-13, CCL1, and CCL3. The β-hexosaminidase assay demonstrated that RE treatment inhibited mast cell degranulation dose-dependently to a maximum (down to 15% of control) at 25 µg/mL RE. Finally, RE reduced NFкB activity. This work suggests that RE is capable of modulating mast cell functional outcomes, and warrants further investigation for use as a potential therapeutic.
The association between blood pressure and vascular characteristics in children
Phillips, Aaron; Applied Health Sciences Program (Brock University, 2010-03-09)
Hypertension is thought to exist in up to five percent of children. A select number of studies have investigated the role elevated blood pressure plays in pediatric atherosclerotic progression. However these studies contain significant methodological flaws and fail to recognize important confounding factors. Therefore, the influence of elevated blood pressure on arterial health in children remains to be clearly understood. The purpose of this study was to investigate the association between blood pressure (BP) and arterial thickness and stiffuess in children. Common carotid artery (CCA) intima-media thickness (IMT) and distensibility (Dist), as well as systemic pulse wave velocity (PWV) were measured in 21 elevated blood pressure (EBP; BP ~ 95th percentile) and 83 normal blood pressure (NBP; BP < 90th percentile) children 11-14 years of age. Both EBP and NBP groups demonstrated BP within the normal clinical range, but EBP showed significantly elevated BP as compared to the NBP group. Independent t-tests failed to show significant differences between the EBP and NBP groups for CCA IMT (0.43 ± 0.05 mm and 0.42 ± 0.06 mm, respectively) and Dist (0.0058 ± 0.0024 mmHg-1 and 0.0064 ± 0.0019 mmHil respectively). In contrast, a significantly elevated PWV (p<O.OOl) was found in the EBP group (423 ± 35 cmls) compared to the NBP group (389 ± 24 cmls). This finding remained constant following an analysis of covariance controlling for the effects of maturation, age, sex and obesity. This study shows for the first time that children with elevated BP do not have significantly altered central arterial structure and function as measured through CCA Dist and IMT, but do possess significantly altered systemic arterial stiffuess as measured through PWV. This may be the result of sympathetic predominance and its significant influence on the peripheral vasculature. More studies are needed to clearly illustrate the temporal sequence of pediatric atherosclerotic progression in response to elevated BP.
The association between body composition and arterial stiffness in peri-pubescent children
Banach, Alayna M.; Applied Health Sciences Program (Brock University, 2006-06-29)
The objective of this study was to examine the association between body composition and arterial stiffuess in peri-pubescent boys and girls. Differences in arterial distensibility were measured in 68 children (45 normal weight, 12 overweight, and 11 obese) between the ages of9 to 12 years. Weight classification was based on age and gender-specific body mass index cut-offs, while pubertal maturation was self-reported using Tanner staging. Distensibility was determined using two-dimensional, B-Mode echo Doppler ultrasound to measure changes at the right common carotid artery (CCA) diameter changes, while carotid pulse pressure (cPP) was measured at the left CCA by applanation tonometry. One-way ANOV A analysis revealed significant differences (p<0.001) in all anthropometric measures between the normal weight and overweight children, as well as the normal weight and obese children. Body stature was only higher in obese children compared to normal weight children (p<0.01). No significant differences were found between groups regarding age or Tanner stage. Common carotid artery distensibility showed a significant difference (p<0.01) between normal weight children (0.008 ± 0.002 mmHg-1 ) compared to obese children (0.005 ± 0.002 mmHg-1 ), with a borderline significant difference between the normal and overweight subjects (p=0.06). There was no significant effect for gender between males and females across all independent variables. The strongest determinants of distensibility in children were cPP (r= -0.52, p<O.OOI), change in diastolic diameter (r= 0.50, p<O.OOI), and sum of 4 skinfold thickness (r= -0.40, p<O.OOI). Regression analysis revealed that cPP alone explained 27% of the variance in distensibility in children. In addition, cPP, diameter difference, systolic and diastolic diameter, as well as waist-to-hip ratio explained 94% of the variance among peri-pubescent children. This study greatly underscores the need for weight management for long-term prevention of cardiovascular disease in overweight and obese children.
ASSOCIATION BETWEEN FAMILY EATING BEHAVIOURS AND SCHOOL CHILDREN ACADEMIC PERFORMANCE
Zheng, Lin; Applied Health Sciences Program
Abstract Objective: To estimate the impact of family eating behaviours on children's academic performance as well as the role of children's nutrition intake. Methods: A total of 2,113 students from grade six in the District School Board of Niagara (DSBN) were recruited. Academic performance was assessed through students' Education Quality and Accountability Office (EQAO) grades, extracurricular activity, leadership and overall academic performance; and family eating behaviours (FEBs) were assessed from both general and specific aspects. Results: The less optimal general eating behaviours of child, mother and overall family were statistically significantly associated with child's more extracurricular activity rather than child's EQAO grades. The less optimal child's specific eating behaviours were associated with child's stronger leadership, more extracurricular activity and better overall academic performance; the less optimal mother's specific eating behaviours were associated with child's poorer EQAO grades on math and overall but stronger leadership and more extracurricular activity; and the less optimal father's specific eating behaviours were associated with child's less extracurricular activity and worse overall academic performance. In addition, "frequently" eating breakfast with parents was associated with child's higher EQAO grades on math, reading, writing, and overall; "sometimes" eating lunch with parents was associated with child's better EQAO math grade; and "frequently" eating snacks with parents was associated with child's better EQAO reading grade but poorer writing and overall grades. Moreover, children's intake of junk foods affected the relationship between overall family general eating behaviours and child's extracurricular activity; children's intake of junk foods also affected the relationship between the child's specific eating behaviours and child's extracurricular activity and overall academic performance; and children's intake of macronutrients, healthy foods or junk foods affected the relationship between the mother's specific eating behaviours and child's EQAO math grade. Conclusions: These findings suggest that FEBs have an impact on children's academic performance with children's nutrition intake acting as an intermediary, thus, the importance of family meals and children's nutrition intake should be emphasized publicly, and family-based interventions should be designed to educate family members as to promote students' educational success.
The association between maternity insurance, residence status and selected perinatal outcomes among Chinese women
Zhang, Jing (Lexie); Applied Health Sciences Program
Objective: To investigate the impact of maternity insurance and maternal residence on birth outcomes in a Chinese population. Methods: Secondary data was analyzed from a perinatal cohort study conducted in the Beichen District of the city of Tianjin, China. A total of 2364 pregnant women participated in this study at approximately 12-week gestation upon registration for receiving prenatal care services. After accounting for missing information for relevant variables, a total of 2309 women with single birth were included in this analysis. Results: A total of 1190 (51.5%) women reported having maternity insurance, and 629 (27.2%) were rural residents. The abnormal birth outcomes were small for gestational age (SGA, n=217 (9.4%)), large for gestational age (LGA, n=248 (10.7%)), birth defect (n=48 (2.1%)) including congenital heart defect (n=32 (1.4%)). In urban areas, having maternal insurance increased the odds of SGA infants (1.32, 95%CI (0.85, 2.04), NS), but decreased the odds of LGA infants (0.92, 95%CI (0.62, 1.36), NS); also decreased the odds of birth defect (0.93, 95%CI (0.37, 2.33), NS), and congenital heart defect (0.65, 95%CI (0.21, 1.99), NS) after adjustment for covariates. In contrast to urban areas, having maternal insurance in rural areas reduced the odds of SGA infants (0.60, 95%CI (0.13, 2.73), NS); but increased the odds of LGA infants (2.16, 95%CI (0.92, 5.04), NS), birth defects (2.48, 95% CI (0.70, 8.80), NS), and congenital heart defect (2.18, 95%CI (0.48, 10.00), NS) after adjustment for the same covariates. Similar results were obtained from Bootstrap methods except that the odds ratio of LGA infants in rural areas for maternal insurance was significant (95%CI (1.13, 4.37)); urban residence was significantly related with lower odds of birth defect (95%CI (0.23, 0.89)) and congenital heart defect (95%CI (0.19, 0.91)). Conclusions: whether having maternal insurance did have an impact on perinatal outcomes, but the impact of maternal insurance on the perinatal outcomes showed differently between women with urban residence and women with rural residence status. However, it is not clear what are the reason causing the observed differences. Thus, more studies are needed.
The Association between Tobacco Control Policies and Marijuana Use among Ontario Undergraduate Students
Macintosh, James; Applied Health Sciences Program (Brock University, 2013-05-15)
Background: Research indicates a steady increase in marijuana use and that it is concurrent with tobacco. There is speculation this concurrency reaches beyond use, to where policies aimed at reducing one may result in the reduction of the other. Purpose: To investigate the association between tobacco control policies and marijuana use among young adult undergraduates. Methods: A stratified sample of Ontario universities resulted in a sample of 4,966 participants. Results: Campuses with a moderately strong policy was found to be significantly associated with decreased marijuana use compared to campuses with a weak tobacco control policy. (OR=0.52, 95% CI: 0.36-0.76). Conclusions: The findings show tobacco control strategies are related to decreased odds of marijuana use among Ontario undergraduates. These findings are important to both policy makers and researchers interested in health strategies pertaining to marijuana and tobacco use and/or how health policies aimed at reducing one risk behaviour can affect another.
The association between "leg length to height ratio" and blood pressure in peri-adolescents
Wijesena, Dilani; Applied Health Sciences Program
Background: Hypertension has a high prevalence in adults, and is a risk factor for cardiovascular diseases (CVD). Children and adolescents with higher levels of blood pressure tend to have high blood pressures as adults. Identifying children with higher levels of blood pressure would be critical for effectively implementing preventive measures among them. Stature components have been found to be associated with the risk of CVD in adults and some CVD risk factors in children. A few studies have found an association between leg length to height ratio (LLHR) and blood pressure in children; however, none of these studies have been in Canada. Objective: To ascertain the relationship between leg length to height ratio and blood pressure in Canadian youth. Methods: This cross- sectional analysis was done using data from the Heart Behavioural Environment Assessment Team (HBEAT) study, which was conducted with students from Niagara Catholic District School Board. Blood pressure and stature components of 689 students between the ages of 9-14 years were included for the analysis. The height range was 106.3 cm to 178.5 cm, and the blood pressure range was 67 mmHg to 142 mmHg for systolic blood pressure, and 30 mmHg to 96 mmHg for diastolic blood pressure. Regression models were used to examine relationships between LLHR and blood pressures. Results: In the regression analyses, for every one standard deviation increment in LLHR, the systolic, diastolic, pulse pressure, and mean arterial pressure were on average 1.08 mmHg (p<0.01), 0.88mmHg (p<0.01), 0.20mmHg and 0.95mmHg (p<0.01) lower after adjusting for selected covariates. Conclusion: Inverse relationships between LLHR and systolic, diastolic, and mean arterial pressure have been observed among Canadian youth. However, whether this can be used to predict the future risk of high blood pressure among children with a lower LLHR needs further studies.
The Association of Energy Intake with Body Mass in Children With and Without Probable Developmental Coordination Disorder
Pryzbek, Michael; Applied Health Sciences Program (Brock University, 2015-01-05)
Objective To determine if there is an association between energy intake (EI) and overweight or obesity status (OWOB) in children with and without probable developmental coordination disorder (p-DCD). Methods 1905 children were included. The Bruininks-Oseretsky Test of Motor Proficiency was used to assess p-DCD, body mass index for OWOB, and the Harvard Food Frequency Questionnaire for EI. Comparative tests and logistic regressions were performed. Results Reported EI was similar between p-DCD and non-DCD children among boys (2291 vs. 2281 kcal/day, p=0.917), but much lower in p-DCD compared to non-DCD girls (1745 vs.. 2068 kcal/day, p=0.007). EI was negatively associated with OWOB in girls only (OR: 0.82 (0.68, 0.98)). Conclusions Girls with p-DCD have a lower reported EI compared to their non-DCD peers. EI is negatively associated with OWOB in girls with p-DCD. Future research is needed to assess longitudinally the potential impact of EI on OWOB in this population.
THE ASSOCIATION OF SEQUENCE OF HIRING PRACTICE AND BIOPHYSICAL COMPONENTS IN SCREENING PROBATIONARY FIREFIGHTERS
Schachtschneider, Carrie; Applied Health Sciences Program (Brock University, 2014-01-23)
Variation in hiring procedures occurs within fire service human resource departments. In this study, City 1 and City 2 applicants were required to pass their biophysical assessments prior to being hired as firefighters at the beginning and end of the screening process, respectively. City 1 applicants demonstrated significantly lower resting heart rate (RHR), resting diastolic blood pressure (RDBP), body fat% (BF) and higher z-scores for BF, trunk flexibility (TF) and overall clinical assessment (p<0.05). Regression analysis found that age and conducting the biophysical assessment at the end of the screening process explained poorer biophysical assessment results in BF% (R2=21%), BF z-score (R2=22%), TF z-score (R2=10%) and overall clinical assessment z-score (R2=7%). Each of RHR (OR=1.06, CI=1.01-1.10), RDBP (OR=1.05, CI=1.00-1.11) and BF% (OR=1.20, CI=1.07-1.37) increased the odds of being a City 2 firefighter (p<0.05). Biophysical screening at the end of the hiring process may result in the hiring of a less healthy firefighter.
Associations Between Personal Cancer History and Lung Cancer Risk
Everett, Karl; Applied Health Sciences Program
The study aim was to investigate the relationship between factors related to personal cancer history and lung cancer risk as well as assess their predictive utility. Characteristics of interest included the number, anatomical site(s), and age of onset of previous cancer(s). Data from the Prostate, Lung, Colorectal and Ovarian Screening (PLCO) Cancer Screening Trial (N = 154,901) and National Lung Screening Trial (N = 53,452) were analysed. Logistic regression models were used to assess the relationships between each variable of interest and 6-year lung cancer risk. Predictive utility was assessed through changes in area-under-the-curve (AUC) after substitution into the PLCOall2014 lung cancer risk prediction model. Previous lung, uterine and oral cancers were strongly and significantly associated with elevated 6-year lung cancer risk after controlling for confounders. None of these refined measures of personal cancer history offered more predictive utility than the simple (yes/no) measure already included in the PLCOall2014 model.
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Home / For Patients and Families / Rare Disease Information / Buerger's Disease
Rare Disease Database
Buerger's Disease
Synonyms of Buerger's Disease
Inflammatory Occlusive Peripheral Vascular Disease
Occlusive Peripheral Vascular Disease
Thromboangiitis Obliterans
Buerger's disease, also known as thromboangiitis obliterans, is a rare disorder that, in most cases, affects young or middle-aged male cigarette smokers. It is characterized by narrowing or blockage (occlusion) of the veins and arteries of the extremities, resulting in reduced blood flow to these areas (peripheral vascular disease). The legs are affected more often than the arms. In most cases, the first symptom is extreme pain of the lower arms and legs while at rest. Affected individuals may also experience cramping in the legs when they walk that, in rare cases, may cause limping (claudication). In addition, affected individuals may have sores (ulcers) on the extremities, numbness and tingling and a lack of normal blood flow to the fingers and/or toes when exposed to cold temperatures (Raynaud's phenomenon), and/or inflammation and clotting of certain veins (thrombophlebitis). In severe cases, individuals with Buerger's disease may exhibit tissue death (gangrene) of affected limbs. The exact cause of Buerger's disease is not known; however, most affected individuals are heavy tobacco users.
Buerger's disease is characterized by narrowing or blockage (occlusion) of the intermediate and/or small sized arteries and veins of the extremities, resulting in reduced blood flow to these areas (peripheral vascular disease). Buerger's disease tends to occur in sudden (acute) episodes that may last from one to four weeks. The disorder runs a recurrent course.
In most cases, the first sign of Buerger's disease is extreme pain in the lower arms and/or legs while at rest. Affected individuals may also experience cramping in the legs when they walk that, in rare cases, may cause affected individuals to limp (claudication). Other physical features associated with Buerger's disease may include sores (ulcers) on the arms and legs, pale discoloration of the hands, numbness and tingling and a lack of normal blood flow to the fingers and/or toes when exposed to cold temperatures (Raynaud's phenomenon), and inflammation and clotting of certain veins (thrombophlebitis). Dry dark ulcerations that often form on the tips of the fingers or toes may be extremely painful. Pain associated with these ulcers may worsen with elevation. In severe cases, individuals with Buerger's disease may exhibit tissue death (gangrene) of the affected areas.
In some cases, arteries and veins of the intestines may also be affected. This may result in extreme heaviness or pain (angina) in the abdomen and weight loss. In extremely rare cases (i.e., fewer than 2 percent), affected individuals have exhibited neurological abnormalities.
The exact cause of Buerger's disease is unknown. However, the use of tobacco is associated with the development of the disorder. In fact, most researchers believe that past or present use of tobacco products by an individual is a requirement for the diagnosis of Buerger's disease. The exact relationship tobacco products have with Buerger's disease is not completely understood.
Some scientists believe that Buerger's disease may be an autoimmune disorder. In some cases, trauma to the hands and feet may contribute to the disorder. Autoimmune disorders are caused when the body's natural defenses against "foreign" or invading organisms (e.g., antibodies) begin to attack healthy tissue for unknown reasons.
Genetic factors may play a role in the development or severity of Buerger's disease because the prevalence varies significantly between ethic groups. More research is necessary to determine the exact role, if any, that genetics plays in the development of the disorder.
The symptoms of Buerger's disease develop because of impaired blood flow (ischemia) to certain areas of the body most often the arms and legs.
Affected Populations
Buerger's disease is a very rare disorder that, in most cases, affects young or middle-aged male cigarette smokers with onset of symptoms before 40-45 years of age. In recent years, more affected women have been reported in the medical literature. Some scientists have speculated that this is due to an increase in the amount of women who smoke. At one time the ratio of affected men to women was 100:1, recent articles in the medical literature have speculated that ratio may be 10:1 or closer. In extremely rare cases, individuals who do not smoke have developed Buerger's disease.
Buerger's disease is extremely rare in the United States and Europe, but more common in other parts of the world, especially in parts of Asia and the Far and Middle East. The incidence in the United States has been estimated at 12.6-20 per 100,000 people in the general population. Buerger's disease occurs with greater frequency in countries that have heavy tobacco use.
Although most cases are associated with cigarette smoking, the disorder has also developed in individuals who did not smoke but used smokeless tobacco (e.g., chewing tobacco).
Related Disorders
Symptoms of the following disorders can be similar to those of Buerger's disease. Comparisons may be useful for a differential diagnosis:
Vasculitis is inflammation of blood vessels. In individuals with vasculitis, inflammation damages the lining of affected blood vessels, causing narrowing, the formation of blood clots (thrombosis), and/or blockage. As a result, there may be restriction of oxygenated blood supply to certain tissues (ischemia), potentially resulting in pain, tissue damage, and, in some cases, malfunction of certain affected organs. Vasculitis may affect veins and arteries of any type or size; may involve a single organ or many organs and tissues of the body; and may be a primary disease process or occur due to or in association with a number of different underlying disorders. Therefore, the range and severity of symptoms and findings associated with vasculitis may vary greatly. The specific underlying cause of vasculitis is not fully understood. However, in most cases, it is thought to be due to disturbances of the body's immune system. (For more information on this disorder, choose "Vasculitis" as your search term in the Rare Disease Database.)
Scleroderma is a rare connective tissue disorder characterized by abnormal thickening of the skin. Connective tissue is composed of collagen, which supports and binds other body tissues. There are several types of scleroderma. Some types affect certain, specific parts of the body, while other types can affect the whole body and internal organs (systemic). The exact cause of scleroderma is unknown. The immune system and vascular system as well as connective tissue metabolism are known to play some role in the disease process. (For more information on this disorder, choose "scleroderma" as your search term in the Rare Disease Database.)
Takayasu arteritis is a rare disorder characterized by inflammation of the large elastic arteries. The main artery of the heart (aorta) and the pulmonary (lung) artery are affected. This disorder causes progressive inflammation of many arteries in the body (polyarteritis), resulting in the reduction of blood flow. Arteries in the head and arms may be affected, and this can result in the loss of the major pulse points in the body. Some people with takayasu arteritis have irregular narrowing of portions of the large arteries (segmental stenosis) and abnormal backward flow of blood from the aorta into the left ventricle of the heart (aortic regurgitation). (For more information on this disorder, choose "Takayasu" as your search term in the Rare Disease Database.)
A diagnosis of Buerger's disease may be made based upon the identification of characteristic physical features and symptoms. Many physicians require a history of recent or current tobacco use in a diagnosis of Buerger's disease. A test such as an angiography or noninvasive techniques may be used to confirm a diagnosis. During an angiography, injection of a specialized dye is used to make the blood vessels visible on x-rays.
Standard Therapies
The treatment of Buerger's disease is symptomatic and supportive. Symptoms usually improve if affected individuals stop smoking. In some cases, when individuals stop smoking complete remission of the disorder may occur.
If an affected individual does not stop smoking, treatment options for Buerger's disease should avoid premature or unnecessary surgery. Conservative treatment may include drugs that prevent the blood from clotting (anticoagulants), drugs that increase the diameter of blood vessels (vasodilators), drugs that prevent inflammation (antiinflammatories), antibiotics, and/or drugs that relieve pain (analgesics).
In some cases surgery may become necessary. Affected individuals have been treated with an operation in which nerve terminals (ganglia) are destroyed to interrupt the nerve pathway and improve blood supply to the affected limb (sympathectomay). In some cases, surgeons may try bypass procedures to get around the blocked or narrow (occluded) veins and/or arteries. In severe cases, surgeons may be forced to remove (amputate) a finger or toe or part of an arm or leg.
Investigational Therapies
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
Revascularization is a type of experimental surgery being investigated as a treatment for Buerger's disease. This type of surgery on veins and arteries may enhance blood circulation if combined with drug therapy (urokinase, PGE1 and heparin), but more research is necessary to determine its safety and long-term effectiveness for individuals with Burger's disease.
Trials have been conducted to test the usefulness of a prostacyclin analogue known as iloprost and a surgical procedure known as omental transfer in the treatment of Buerger's disease. Iloprost alleviated pain and healed ulcers. Omental transfer helped to increase blood flow to the affected areas and alleviated pain and skin abnormalities. However, more studies are needed to determine the long-term safety and effectiveness or these options in the treatment of Buerger's disease.
Additional therapies are being studied for the treatment of Buerger's disease. Growth factors that stimulate angiogenesis to speed up healing and alleviate pain may be beneficial. Implantable nerve stimulators have been studied to treat pain associated with Buerger's disease.
In cases where other therapies have failed, a drug known as treprostinil sodium has been tried. Initial results demonstrate that this drug may be clinically useful for the treatment of affected individuals. More research is necessary to determine the long-term safety and effectiveness of this drug for the treatment of Buerger's disease.
NORD Member Organizations
Vasculitis Foundation
Kansas City, MO 64188 USA
Website: http://www.vasculitisfoundation.org
Genetic and Rare Diseases (GARD) Information Center
Website: http://rarediseases.info.nih.gov/GARD/
NIH/National Heart, Lung and Blood Institute
Website: http://www.nhlbi.nih.gov/
Vascular Cures
555 Price Avenue
Website: http://www.vascularcures.org/
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FROM THE INTERNET
Hanly EJ. Buerger's Disease (Thromboangiitis Obliterans). Last Updated: August 8, 2005. 9pp. Available at: http://www.emedicine.com/med/topic253.htm Accessed on: February 12, 2006.
Beers MH, Ed. The Merck Manual of Medical Information [book online]. Merck Research Laboratories. 2004-2005. Available at: http://www.merck.com/mrkshared/mmanual/section16/chapter212/212c.jsp Accessed on: February 12, 2006.
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Leeper Group
Miguel A. Matilla*, Rita E. Monson, Annabel Murphy, Muriel Schicketanz, Alison Rawlinson, Caia Duncan, Juan Mata, Finian J. Leeper, George P. C. Salmond*
"Solanimycin: Biosynthesis and Distribution of a New Antifungal Antibiotic Regulated by Two Quorum-Sensing Systems"
mBio, 2022, (), . Full text
The increasing emergence of drug-resistant fungal infections has necessitated a search for new compounds capable of combating fungal pathogens of plants, animals, and humans. Microorganisms represent the main source of antibiotics with applicability in agriculture and in the clinic, but many aspects of their metabolic potential remain to be explored. This report describes the discovery and characterization of a new antifungal compound, solanimycin, produced by a hybrid polyketide/nonribosomal peptide (PKS/NRPS) system in Dickeya solani, the enterobacterial pathogen of potato. Solanimycin was active against a broad range of plant-pathogenic fungi of global economic concern and the human pathogen Candida albicans. The genomic cluster responsible for solanimycin production was defined and analyzed to identify the corresponding biosynthetic proteins, which include four multimodular PKS/NRPS proteins and several tailoring enzymes. Antifungal production in D. solani was enhanced in response to experimental conditions found in infected potato tubers and high-density fungal cultures. Solanimycin biosynthesis was cell density dependent in D. solani and was controlled by both the ExpIR acyl-homoserine lactone and Vfm quorum-sensing systems of the bacterial phytopathogen. The expression of the solanimycin cluster was also regulated at the post-transcriptional level, with the regulator RsmA playing a major role. The solanimycin biosynthetic cluster was conserved across phylogenetically distant bacterial genera, and multiple pieces of evidence support that the corresponding gene clusters were acquired by horizontal gene transfer. Given its potent broad-range antifungal properties, this study suggests that solanimycin and related molecules may have potential utility for agricultural and clinical exploitation.
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types of admission in psychiatric hospital
Although the rate of such admissions is tending to rise in several Western countries, there is little qualitative research on the mental health-care process preceding compulsory admission. The aim of the study is to describe the safety and security measures currently applied in the 18 psychiatric admission wards of the one and only psychiatric hospital in the Kingdom of Bahrain. 2. types of admission in psychiatric hospital. Often, that means a person's health insurance company may require a pre-admission certification before agreeing to pay for a hospitalization. Psychiatric admissions may be voluntary or involuntary. A psychiatric hospital may elect to participate in its entirety, or it may designate a distinct part and apply for Medicare participation of that portion. Psychiatric Admission. A decrease in number of psychiatric admissions, typically measured over 30 days, 90 days, or 1 year, is an important measure of successful outpatient mental health treatment. Admission Process at Chicago Lakeshore Hospital. There are 14 community mental health centres in the region. In most U.S. states, however, these voluntary admissions abridge the rights of patients through legal provisions that limit the condi … Along with the advances in civil rights protections for psychiatric patients since the 1970s, so-called voluntary inpatient psychiatric admissions have become common. I offer these pointers because knowing what I know now back then would have helped me get through the experience with less angst. This means that if emergency inpatient admissions related to mental health are excluded, the MH cohort experienced 3.9 times more emergency inpatient admissions … Chapter 21 Standardised criteria for hospital admission 5 21 Standardised criteria for hospital admission 21.1 Introduction Many standardised tools for aiding decisions relating to admission to hospital already exist and can apply to a wide variety of the acute medical emergency spectrum of illness: The admission and stay in an inpatient mental health service path for the transition between community or care home and inpatient mental health settings pathway. The following five types of admission were specified under sections 41 to 49 of the Mental Health Act 1959:Voluntary Boarders (V) were those who entered the hospital at their own request or, if under the age of 16 at the request of a parent or guardian and on the opinion of a medical practitioner.Recommended (R) and Approved (A) Patients. An individual may need in-patient hospital care for a psychiatric condition; that care may be provided at a medical hospital or at a psychiatric hospital. The author's objective is that of detailing the oversimplified concept of voluntary and non-voluntary admission to a psychiatric hospital. requirement appears in Section 1.2–3.6, Behavioral and Mental Health (Psychiatric Patient Injury and Suicide Prevention), which also specifies that "behavioral and mental health patient care settings . This type of psychiatric service is critical as it provides around-the-clock care for those who may be severely ill. ; Almost 1 in 4 (23.2%) of same day, admitted mental health-related separations with specialised psychiatric care in public hospitals had a principal diagnosis of Depressive episode. December 21, 2019 Psychiatry and Psychology Services. ADMISSION : It means allowing a client to stay in the hospital for observation, investigations and treatment of disease he is suffering from. If you have a mental condition, you may be admitted into a public mental health institution.There are many different mental health problems with different symptoms. Emergent hospital admissions usually happen when a patient seen in the emergency department is subsequently admitted to the hospital. Perform Admission Procedure : A. . The University Psychiatric Hospital in Northern Norway (UNN) in Tromsø, and Nordland Hospital (NLSH) in Bodø, participated in the study. Mental illness and/or chemical dependency can be complicated and confusing, and each patient we treat requires an individual path of care to recovery. In 2018–19, there were 59,888 same day admitted mental health-related separations from public hospitals of which almost one third (31.5%) included specialised psychiatric care. 4. Studies are divided on the question of how closely legal standards prevail in the decision to involuntarily admit a patient to a psychiatric hospital. At the time of admission, the registered nurse perform complete assessment of the patient. Activity based funding: Mental health care NBEDS 2020–21 Health, Standard 17/01/2020. 1. OBJECTIVES •Admission- types •Admission procedure •Preparation of unit •Transfer procedure •Role of nurse 3. As a premier Chicago hospital for behavioral health, Chicago Lakeshore Hospital is here to support and guide you through the recovery process. For the MH cohort, just 19 per cent of emergency inpatient admissions was directly related to patients' mental health needs. Billing Scenarios: Inpatient Hospital Psychiatric Admissions. Compulsory admissions have a strong effect on psychiatric patients and represent a deprivation of personal liberty. The cur- rent study attempts to understand how different admission and commitment sta- tuses are applied in the psychiatric emer- gency room. Voluntary admission (also known as a "201") to an acute inpatient psychiatric hospital occurs when a person goes for psychiatric evaluation and the evaluating mental health provider and patient agree that the patient would benefit from hospitalization and meets criteria for hospitalization. With increasing pressure to decrease health care costs, reducing hospital bed days (psychiatric or otherwise) is often a key priority for providers and insurers. To learn more information about our admissions process check out FullerHospital.com The admission and experience of staying in the psych ward was quite an adventure. Free and confidential assessments are available 24/7/365, no appointment necessary. There are times when a family member or care provider becomes concerned about an individual's mental health. Types of Psychiatric Admissions in Pennsylvania. Patterns of hospital admission for adult psychiatric illness in England: analysis of Hospital Episode Statistics data - Volume 185 Issue 4 - Andrew Thompson, Mary Shaw, Glynn Harrison, Davidson Ho, David Gunnell, Julia Verne ; Depressive episode (15.7%) and Schizophrenia (13.6%) were the most common diagnoses for overnight mental health-related separations with specialised psychiatric care. Patient Category Preparation of Admitting Patient : Entrance of a patient into the ward or unit for evaluation or treatment is called admission. Seeking care when you, or a loved one, are in need takes a lot of courage. DISCHARGE OF VOLUNTARY PATIENTS FROM, PSYCHIATRIC HOSPITAL Section 8. Alternative to inpatient admission: Acute psychiatric day hospital care Acute psychiatric day hospitals were the subject of a systematic review published in the Cochrane Library in 2002 (2) that identified nine randomized controlled trials of day hospital versus inpatient care, published between 1964 and 1997 (3–11). Emergency psychiatry is the clinical application of psychiatry in emergency settings. Emergency admission. 271,040 overnight admitted mental health-related hospital separations occurred in 2018–19, of which 63.2% included specialised psychiatric care. While it was an unfamiliar and uncomfortable place to be, it was also the best place for me and worth it for my mental health. Nurses need to follow strict protocol regarding admission and discharge in the hospital. . (1) Except as may be otherwise expressly provided in any other written law, no person shall be admitted into a psychiatric hospital otherwise than— He proposes to measure consent using a scale comprising five categories to which were assigned 200 first admissions to the Clinic of Nant in 1982. Admission of patient into psychiatric hospital. Elective hospital admissions occur when a doctor requests a bed to be reserved for a patient on a specific day. Some are more serious than others in … Fuller Hospital intake department is available 24/7. But when does a person with a psychiatric problem need inpatient care? The procedure for hospital admission for a psychiatric illness resembles that for other illnesses. Depending on the purpose of your hospital stay, there are different types of hospital admissions, including: emergency (unplanned) overnight or extended (planned) maternity (planned) day procedure. Activity based funding: Mental health care NBEDS 2021–22 Health, Candidate 29/10/2020. Immediate assistance is possible at our mental health facility in South Attleboro, MA. the psychiatric emergency room. Patients are admitted to TMH from different sources: OPD - Doctors may advise for admission to the respective ward.. Casualty - Emergency patients are treated and/or admitted if required.. Labour room - Gynecological or Obstetric patients are treated and advised for admission.. TMH doctors directly admit patients from their private clinics also.. The main objectives of the mobile Psychiatric Emergency Services (PES) in the Netherlands are to assess the presence of a mental disorder, to estimate risk to self or others, and to initiate continuity of care, including psychiatric hospital admission. Mental Health Assessments. shall be designed to protect the privacy, dignity, and health of patients and address the potential risks related to patient elopement Conditions requiring psychiatric interventions may include attempted suicide, substance abuse, depression, psychosis, violence or other rapid changes in behavior.Psychiatric emergency services are rendered by professionals in the fields of medicine, nursing, psychology and social work. Just as people may require admission to hospital for assessment and treatment of their physical health problems, some people may require admission to a mental health (psychiatric) inpatient unit for the assessment and treatment of their mental health … Print Hospital admissions for mental illness. Acute hospital and private psychiatric hospital admission labour force status code N … All admissions to psychiatric hospital in the region with a population of about 500,000 people are administered by these two hospitals. Moreover, psychiatric hospitals also provide the needed medical expertise to observe how treatment is progressing. About admission into a mental health institution by consent. Telephone triple zero for medical emergencies. Some studies When you contact Bakersfield Behavioral Healthcare Hospital about mental health treatment for you or a loved one, we begin the admissions process with a free and confidential assessment. TYPES OF ADMISSION 1. hospital discharge under the mental health act Planning for a person's discharge should begin as soon as possible after a person's admission. Types of hospital admission. In general, there are two major types of hospital admissions, emergent and elective. Also provide the needed medical expertise to observe how treatment is progressing then would have helped me through... Individual 's mental health facility in South Attleboro, MA involuntarily admit a patient seen in region. Occur when a doctor requests a bed to be reserved for a illness... 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types of admission in psychiatric hospital 2020
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Pretty Perky Peggy King
Does vitamin C interfere with tamoxifen?
Can you eat grapefruit while taking tamoxifen?
Does ginger interfere with tamoxifen?
Can I drink wine while taking tamoxifen?
Is it OK to eat fruit while taking tamoxifen?
Can a tangerine peel lessen the effectiveness of tamoxifen?
What foods to avoid when taking tamoxifen for breast cancer?
Can a grapefruit juice block reduce the effect of tamoxifen?
No interactions were found between tamoxifen and Vitamin C.
Many drug-interaction resources specifically advise that women taking tamoxifen avoid grapefruit. For this reason, you shouldn't drink grapefruit juice or regularly eat whole grapefruit if you are taking tamoxifen or other medications to reduce your breast cancer risk.
About 40% of women treated with tamoxifen and almost all patients with metastatic disease experience relapse that leads to death. Breast cancer is not the first to be susceptible to ginger; colorectal, liver, lung, pancreatic, skin, and prostate cancers have also been shown to be inhibited by ginger.
Alcohol can raise the risk of side effects with tamoxifen, some of which can be serious. Alcohol makes it harder for tamoxifen to work properly and should be limited or avoided while you're taking this medication. Alcohol can raise your risk of developing breast cancer.
The flesh of the fruit contains much less tangeretin than the peels, so eating moderate amounts of the fruit is unlikely to cause a significant lessening of tamoxifen's effectiveness. Confusion about the health effects of soy foods arises from the term "phytoestrogens."
Answer: Tangeretin, a nutrient found in abundance in tangerine peels, can lessen the effectiveness of tamoxifen. The flesh of the fruit contains much less tangeretin than the peels, so eating moderate amounts of the fruit is unlikely to cause a significant lessening of tamoxifen's effectiveness.
Tamoxifen is no different. You certainly don't want to take a medication to reduce breast cancer risk, only to eat or drink something that renders the tamoxifen less effective. The foods of most concern for women taking tamoxifen are grapefruit and tangerines. Grapefruit is well-known to interfere with numerous medications.
Research has shown that the enzyme that components of grapefruit juice block [CYP3A4] is very important for the production of endoxifen and can reduce the effect of the tamoxifen treatment as a whole."
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The US Department of Defense (DoD) is looking for ways to overcome inadequate physical fitness that challenges a warfighter's readiness. The PHITE Trial is designed to help meet this challenge. Supported by the DoD Office of Naval Research (ONR), PHITE is a 12-wk, two-arm, single-blind, randomized, exercise dose-response trial comparing two intensities of combined exercise training – Moderate Intensity vs. High-Intensity – to determine the effect of exercise dose on performance optimization and the underlying molecular mechanisms, with a focus on epigenetics. The term epigenetics refers to heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence; i.e. a change in phenotype (the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment) without a change in genotype (the genetic constitution of an individual organism). This in turn affects how cells read the genes. Epigenetic change is a regular and natural occurrence but can also be influenced by several factors including age, the environment/lifestyle, and disease state. The PHITE Trial is designed to assess whether epigenetics is a primary mechanism modulating how individuals adapt to specific exercise training prescriptions designed to produce a warfighter phenotype.
The PHITE collaborative team consists of Tim Broderick, MD (Overall PI), Wright State University (WSU); Marcas Bamman, PhD (Site PI), The University of Alabama at Birmingham (UAB); and Ron Evans, PhD and Joe Ecker, PhD, Salk Institute for Biological Studies. The team is organized around a shared test population of human subjects for which UAB oversees all recruitment, training, testing, and sampling. Healthy but untrained volunteers, both men and women, 18-27 y of age, similar to the US warfighter, are being recruited.
Come join the PHITE Club!
Benefits: Participants will receive supervised exercise training with certified trainers, valuable information about their health, and compensation for their time.
Participants: 18-27 years of age; no history of regular endurance or resistance training within the past year; must meet all other inclusion and exclusion criteria determined during screening.
If you may be interested in participating and want to learn more, please complete the questionnaire below and a member of our research staff will contact you soon. You may also call 205-996-0855. Thank you for your interest.
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The effects of jury size and polling method on the process and product of jury deliberation.
Kerr, Norbert L., MacCoun, Robert J. (1985) The effects of jury size and polling method on the process and product of jury deliberation. Journal of Personality and Social Psychology, 48 (2). pp. 349-363. ISSN 0022-3514. E-ISSN 1939-1315. (doi:10.1037//0022-3514.48.2.349) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)
http://dx.doi.org/10.1037//0022-3514.48.2.349
612 undergraduates in 15 same-sex groups of 3, 6, or 12 Ss participated in mock jury deliberations over 9 armed robbery cases, and both individual and group verdicts were obtained, to test the predictions that larger juries would hang more often, particularly for close cases, and that secret polling would lead to fewer hung juries than open polling. It is asserted that failures to confirm these predictions in previous studies were probably due to inadequate sample sizes or to insufficiently close cases; the present study minimized these problems. Social decision scheme and social transition scheme analyses permitted comparisons of the decision-making processes of the different-sized mock juries, and jury groups used either secret written ballots or a show of hands for polling. Results show that, as group size increased, the observed probability of a hung jury significantly increased. No process differences between 6- and 12-person groups were detected, but 3-person groups exhibited several process differences in comparison to both larger groups. When cases were close, the likelihood of a hung jury for typically sized juries was found to be lower when the group was polled by secret ballot than when a show-of-hands was used.
10.1037//0022-3514.48.2.349
Faculties > Social Sciences > School of Psychology
M.L. Barnoux
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Standard Historical Last Updated: Mar 10, 2014
Standard Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting
Significance and Use
Measurements of frictional properties may be made on a film or sheeting specimen when sliding over itself or over another substance. The coefficients of friction are related to the slip properties of plastic films that are of wide interest in packaging applications. These methods yield empirical data for control purposes in film production. Correlation of test results with actual performance can usually be established.
This test method includes testing at temperatures other than 23°C by heating only the plane while the sled is at ambient temperature.
Slip properties are generated by additives in some plastic films, for example, polyethylene. These additives have varying degrees of compatibility with the film matrix. Some of them bloom, or exude to the surface, lubricating it and making it more slippery. Because this blooming action may not always be uniform on all areas of the film surface, values from these tests may be limited in reproducibility.
The frictional properties of plastic film and sheeting may be dependent on the uniformity of the rate of motion between the two surfaces. Care should be exercised to ensure that the rate of motion of the equipment is as carefully controlled as possible.
Data obtained by these procedures may be extremely sensitive to the age of the film or sheet and the condition of the surfaces. The blooming action of many slip additives is time-dependent. For this reason, it is sometimes meaningless to compare slip and friction properties of films or sheets produced at different times, unless it is desired to study this effect.
Frictional and slip properties of plastic film and sheeting are based on measurements of surface phenomena. Where products have been made by different processes, or even on different machines by the same process, their surfaces may be dependent on the equipment or its running conditions. Such factors must be weighed in evaluating data from these methods.
The measurement of the static coefficient of friction is highly dependent on the rate of loading and on the amount of blocking occurring between the loaded sled and the platform due to variation in time before motion is initiated.
Care should be exercised to make certain that the speed of response of the recorder, either electronic or mechanical, is not exceeded.
For many materials, there may be a specification that requires the use of this test method, but with some procedural modifications that take precedence when adhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table 1 of Classification System D4000 lists the ASTM materials standards that currently exist.
1.1 This test method covers determination of the coefficients of starting and sliding friction of plastic film and sheeting when sliding over itself or other substances at specified test conditions. The procedure permits the use of a stationary sled with a moving plane, or a moving sled with a stationary plane. Both procedures yield the same coefficients of friction values for a given sample.
Note 1—For the frictional characteristics of plastic films partially wrapped around a cylinder, or capstan, see Test Method G143 under the jurisdiction of ASTM Subcommittee G02.50.
1.2 Test data obtained by this test method is relevant and appropriate for use in engineering design.
1.2.1 As an option to this test, coefficient of friction may be run at temperatures other than 23°C by heating only the plane while the sled is at ambient temperature.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific precautionary statement, see the end of 6.5.
Note 2—This test method is not equivalent to ISO 8295–1995, and results cannot be directly compared between the two methods.
D1894-11E01
D1894-14 Active D1894-11 D1894-08 D1894-06 D1894-01 D1894-00
Developed by Subcommittee: D20.19
DOI: 10.1520/D1894-11E01
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Acta Veterinaria Scandinavica
Development of a virus neutralisation test to detect antibodies against Schmallenberg virus and serological results in suspect and infected herds
Willie Loeffen1,
Sjaak Quak1,
Els de Boer-Luijtze1,
Marcel Hulst2,
Wim van der Poel1,
Ruth Bouwstra1 &
Riks Maas1
Acta Veterinaria Scandinavica volume 54, Article number: 44 (2012) Cite this article
At the end of 2011, a new orthobunyavirus, tentatively named Schmallenberg virus (SBV), was discovered in Germany. This virus has since been associated with clinical signs of decreased milk production, watery diarrhoea and fever in dairy cows, and subsequently also with congenital malformations in calves, lambs and goat kids. In affected countries, initial surveillance for the infection was based on examination of malformed progeny. These suspicions were followed up by real-time reverse transcription polymerase chain reaction (RT-PCR) on brain tissue. For epidemiological purposes, a serological assay was, however, needed.
A virus neutralisation test (VNT) was developed and optimized, and subsequently evaluated. This VNT has a specificity of >99% and the sensitivity is likely also very close to 100%. The assay is highly repeatable and reproducible. The final assay was used to test for antibodies in cows, ewes and does from herds known to be infected or suspected to be so. Targets for sampling in these herds were the mothers of malformed offspring. In herds with an RT-PCR confirmed SBV infection, more than 94% (190 out of 201) of the ewes and 99% (145 out of 146) of the cows were seropositive. In herds with suspicion of SBV infection based on birth of malformed offspring only (no or negative RT-PCR), more than 90% (231 out of 255) of the ewes and 95% (795 out of 834) of the cows were seropositive. In goats, on the other hand, only a low number of seropositives was found: overall 36.4%, being 16 out of 44 goats tested.
Given the characteristics of this VNT, it can be used at a relative high throughput for testing of animals for export, surveillance, screening and research purposes, but can also be used as a confirmation test for commercially available enzyme-linked immunosorbent assays (ELISA's) and for (relative) quantification of antibodies.
Suspicions of SBV infections that were confirmed by RT-PCR were almost always confirmed by serology in cows. Due to individual registration and identification of cows and calves, affected offspring could almost always be traced back to the mother. Ewes on the other hand were not always the mothers of affected lambs, but were in many cases herd mates with unaffected lambs. This indicated a high within-herd seroprevalence of antibodies against SBV.
On the 18th of November 2011, the finding of a new orthobunyavirus was reported by the Friedrich Loeffler Institute (FLI) in Germany[1]. This virus is closely related to Shamondavirus, which belongs to the Simbu serogroup of the genus Orthobunyavirus, family Bunyaviridae[2]. The virus, provisionally called Schmallenberg virus (SBV), has since been associated with clinical signs of decreased milk production, watery diarrhoea and fever that had occurred in the months of August and September in dairy cows in the Netherlands[3] and Germany[1]. In Germany, twelve samples from six affected herds that were tested with a real-time reverse transcription polymerase chain reaction test (RT-PCR) were positive for viral RNA of SBV[1]. In the Netherlands, using the same RT-PCR, viral RNA of SBV was detected in 36% of stored blood samples from herds that had reported clinical signs earlier. In contrast, none of the samples from herds without clinical signs in the Netherlands were RT-PCR positive for SBV[3].
Subsequently, SBV infections were also associated with congenital arthrogryposis and hydranencephaly syndrome in newborn lambs[4]. A first malformed goat kid was reported PCR-positive for SBV on 3 January 2012 in the Netherlands[5] and the first malformed calf was reported PCR-positive for SBV on 7 January 2012 in Germany[6].
To determine the seroprevalence and carry out epidemiological studies, the immediate need arose for a reliable and robust serological assay. To address this need, a virus neutralisation test (VNT) was developed, as this also allows for a semiquantitative detection of antibodies against the virus. Furthermore, a protocol was established that allows for a relatively high throughput. Even though in April 2012 a first commercial enzyme-linked immunosorbent assay (ELISA) became available, a VNT remains a possible alternative as a screening test, but is also useful as a confirmation test or a semiquantitative test to be used in experimental infections, when amounts of antibodies need to be determined. The development of the VNT is described, evaluating the diagnostic specificity and sensitivity, repeatability and reproducibility, and robustness, and use of the test on RT-PCR positive herds and herds suspected to be infected, i.e. occurrence of malformed progeny, with negative RT-PCR results or RT-PCR not performed.
The medium used was DMEM + Glutamax (Gibco, Bleiswijk, the Netherlands) with 3% foetal calf serum (FCS), penicillin (100 units/ml), and streptomycin (100 μg/ml). FCS was inactivated for 30 min at 56°C. This medium was used in all cell cultures and to dilute serum samples and virus stock.
Vero cells were used to grow the virus and also in the VNT. They were grown in 600 ml (150 cm2) cell culture flasks (Becton Dickinson, Breda, the Netherlands). Depending on the need for cells and availability of cells, flasks were seeded with 6 to 10 million cells, with 50 ml of medium, and incubated at 37°C, in an atmosphere of 5% CO2. Cells for the VNT were counted with a cell counter (Beckman Coulter, Woerden, the Netherlands) and diluted to a concentration of 2x105 cells/ml.
The virus for the VNT was isolated from the brain of a new-born lamb with malformations that had tested positive in the SBV RT-PCR. A virus stock containing approximately 105 median tissue culture infective dose (TCID50) per ml (3rd passage) was grown initially on Vero cells and used to develop and optimize the VNT. A second, larger batch of virus, with a titre of approximately 106.7 TCID50/ml (4th passage) was grown also on Vero cells and used for the initial validation of the final test protocol and subsequent routine diagnostic tests. Titres were determined by amido black staining, similar to back titration of the virus in the VNT (see paragraph "Back titration of virus").
Development of the VNT
Several variables were changed and tested during the development of the assay to determine the optimal conditions, but also the robustness of the VNT:
Number of cells per well: 5000, 10,000, 20,000, and 50,000.
Age of cells (time to harvesting after incubation): 3 to 16 days.
Percentage of FCS in medium: 1%, 3%, and 5%.
Neutralisation time: 1, 2, and 4 hours.
Incubation period: 3, 4, and 5 days.
Amount of virus: 100 and 500 TCID50.
Two different batches of FCS.
Microscopic reading of the plates without staining (cytopathic effect [CPE]) vs. macroscopic reading of the plates after amido black staining.
Final VNT protocol
The VNT was carried out in flat bottomed 96 well micro titre plates. In each well of the first column, 75 μl of medium was pipetted, in all other wells 50 μl of medium. Serum samples were inactivated for 30 min at 56°C and 25 μl was subsequently added to a well in the first column to obtain a starting dilution of 1:4. From this well, two-fold dilutions were made by pipetting 50 μl of each well in the next, until the last column. From the final column, 50 μl was discarded, so that each well now contained 50 μl of the diluted sample.
Subsequently, virus (500 TCID50 per well) was added to each well, also in a volume of 50 μl. Serum and virus were pre-incubated at 37°C for 1 to 2 hours to allow neutralisation of the virus. Thereafter, 20,000 cells per well were added in a volume of 100 μl. Plates were then incubated for 5 days at 37°C and under 5% CO2.
After 5 days, the plates were emptied, washed once with 0.15 M NaCl and then stained with amido black (0.1% amido black solution (w/w) with 5.4% acetic acid, 0.7% sodium acetate and 10% glycerol) for 30 min. Washing fluids were caught in a container with disinfectant, to inactivate the virus. Subsequently, plates were rinsed with tap water and read macroscopically. Wells with 25-100% staining were considered to have no or limited CPE only. Wells with less than 25% staining were considered to have extensive or full CPE. In each dilution series the last well with no or limited CPE (25-100% staining) was identified and the sample was assigned a titre that was the reciprocal of the dilution in that well.
Control samples
Control samples included serum samples from 2 seronegative sheep, 4 seropositive sheep and 2 seropositive dairy cows. The positive samples were obtained from sheep and dairy cows from herds in which congenital malformations were seen and confirmed by RT-PCR. The samples had tested consistently positive in subsequent prototypes of the VNT. These control samples were included in each run of the test and were also used to optimize the assay.
Back titration of virus
Virus used in each run of the test was back titrated in 4 tenfold dilutions. If a working stock of 100 TCID50/well was used in the test, 100, 10-1, 10-2, and 10-3 dilutions of that working stock were used in the back titration. If a working stock of 500 TCID50/well was used in the test, 10-1, 10-2, 10-3 and 10-4 dilutions of that working stock were used in the back titration. Each dilution was tested in 12 or 24 wells during the development phase and routine diagnostic phase respectively. The virus titre was determined with the Reed-Münch method[7].
Diagnostic specificity and sensitivity
To determine the optimal cut-off of the assay, with a high diagnostic specificity and sensitivity, 348 blood samples from non-infected animals were tested in the final version of the assay. These samples originated from the Netherlands from the period of 2000–2010, supposedly before the introduction of SBV. From sheep 156 samples were available and 192 from cattle. They were used to set the cut-off value in the assay and estimate the specificity. Subsequently, 366 field samples were tested that originated from herds in which congenital malformations were observed to get a first indication of the sensitivity of the test.
Repeatability and reproducibility
To test for repeatability of the assay, 646 samples from suspect and infected herds were tested in duplicate, in 8 dilutions. The number of mismatches between duplicates was tabulated to get a first indication of the repeatability. For reproducibility, the results from the control panel of 4 runs were used. For each sample the standard deviation of the log-transformed titres was calculated. The standard deviations of all 8 samples were averaged, to get a first indication of the reproducibility.
From the end of February 2012 both an RT-PCR and the VNT were used as routine diagnostic tests to confirm or rule out SBV infections in case of congenital malformation. The samples used in this study were collected in the field from the end of December 2011 until the 14th of May 2012. Common procedure was that malformed calves, lambs and goat kids would be submitted for a post-mortem. If an infection with SBV was suspected, based on arthrogryposis and hydranencephaly, a brain sample was tested by RT-PCR for SBV, while the competent authorities would trace the mother of the affected offspring to take a blood sample for serological testing. However, tracing of the mother was not always possible, especially in sheep due to lack of individual registration of mothers and lambs at that age. Therefore, in many cases a ewe that was not the mother of the malformed lamb would be sampled from the herd instead. Until mid-May, a total number of 1480 blood samples were tested in the VNT, originating from 1205 different herds (30 goat, 259 sheep and 916 cattle herds). These herds were divided in two categories:
Suspect herds, being herds with occurrence of malformed progeny, but either no or only negative RT-PCR results.
Infected herds, being herds with occurrence of malformed progeny, and a positive RT-PCR result.
All samples were tested in the final VNT-protocol that was evaluated as described above.
Development of the assay and robustness
Several variables were tested and evaluated while developing and optimizing the assay. Percentage of FCS (from 1-5%), neutralisation time (1–4 hours), age of cells (3 to 16 days), and different batches of FCS gave the same result and were not crucial within the tested range. The percentage of FCS was therefore fixed at 3%, with a neutralisation time of 1–2 hours for the final protocol. The test is, however, robust for these variables, within given ranges.
The number of cells, on the other hand, was crucial. A total of 20,000 cells per well gave confluent monolayers and full staining of non-affected cells, while 5,000 or 10,000 cells per well gave rather thin and sometimes incomplete monolayers. Especially for easiness of reading, 20,000 cells per well was included in the final protocol, as 50,000 cells per well gave no further improvement.
Microscopic reading of the plates turned out to be laborious and quite difficult to standardize between observers who were reading the test. Given the need for a relatively high throughput VNT, this was abandoned in favour of amido black staining and macroscopic reading of the plates. Even though CPE was defined as 75% of the monolayer gone, which seems a somewhat subjective criterion, this was very easy to standardize between observers and rarely resulted in discrepancies.
For the amido black staining, crucial differences were noticed when using different virus concentrations and incubation periods. These results are shown in Table 1 and Figure 1, where test plates were prepared in triplicate, of which one plate was stained and read after 3, 4 and 5 days respectively. In Table 1 it is shown that back titration of the virus yields higher titres when plates are read microscopically and that higher titres are observed after longer incubation periods. Serum titres are higher when using 100 TCID50 instead of 500 TCID50 (as can be expected), and serum titres are decreasing after longer incubation periods, as more CPE develops. In Figure 1 it is clearly shown that incubation for a longer period results in plates that are easier to read. Especially after 5 days, and with 500 TCID50, there is a good contrast between wells with and without CPE. This is even more so the case for the back titration of the virus. An incubation period of 5 days and 500 TCID50 were therefore included in the final protocol.
Table 1 Back titrations (in TCID 50 /well) and average titres of positive (n = 6) and negative (n = 2) samples, depending on intended TCID 50 per well (100 vs. 500) and days of incubation of the VNT (3, 4, or 5 days)
Amido black staining of control plates, for comparison of 100 vs. 500 TCID 50 and 3, 4 and 5 days of incubation. A: Back titrations of both virus concentrations, shown in the upper 3 plates, were carried out on one plate per incubation period, in 4 tenfold dilutions starting from 100 (100 TCID50, upper 4 rows) or 10-1 (500 TCID50, lower 4 rows). B: Results of the control panel of 6 positive (P) and 2 negative (N) samples, are shown in the middle row of 3 plates (100 TCID50) and the lower row of 3 plates (500 TCID50). Serum dilutions are shown above the figures. Results of back titration and average titres are given in Table 1.
Diagnostic specificity of the VNT
In serum samples from non-infected sheep, a higher background was seen than in sera from non-infected cattle (Figure 2). Based on testing 156 sheep and 192 cows, the cut-off values were set at a titre of 16 for sheep and 8 for cattle. Given this cut-off value, a specificity of 99.4% (95% CI: 96.6-99.9%) in sheep and 99.5% (95% CI: 97.1-99.9%) in cattle was estimated (Figure 2). No negative samples from goats were available, and the cut-off value was set to 16, similar to sheep.
Distribution of titres in non-infected sheep (n = 156) and cattle (n = 192) (bars, left axis). Serum samples were tested in two fold dilutions from 1:4 until 1:128. Specificity of the VNT in sheep and cattle serum samples, depending on cut-off value (a cut-off value of 4 meaning that all titres of 4 and above are considered positive, etc.) for sheep and cattle is shown with the lines (right axis).
Diagnostic sensitivity of the VNT
Due to the lack of well-defined serum samples, no real estimate of the diagnostic sensitivity was initially possible. From the 366 field samples that were tested during the evaluation of the final test protocol, 92% of the cattle and 94% of the sheep scored positive in the VNT. In sheep no titres of 8 and in cattle no titres of 4 were observed, thus clearly separating the peak of the positive samples from the peak of the negative samples (Figure 3). This supports the cut-off value of 16 and 8 respectively for sheep and cattle, as determined already by testing serum samples from non-infected animals. Assuming the worst case scenario, that all were seropositive in reality, sensitivity of the assay would therefore be at least 92% and 94% in cattle and sheep respectively. However, the clear separation of the negative and positive peak suggests that the sensitivity for both species is close to 100%. In goats only 8 samples were positive, out of 36 samples tested.
Distribution of titres in goats, sheep and cattle in a total of 366 samples from herds with congenital malformations.
From 646 samples tested in duplicate, 398 (61.6%) were identical. In 235 samples (36.4%) there was one dilution step difference between the duplicates and in 11 samples (1.7%) the difference was two dilution steps. In two samples (0.3%) the difference was 5 and 6 dilution steps respectively, and these were the only 2 samples in which the qualitative result (positive/negative) would be different if the result was to be based on either of the duplicates. Based on qualitative results, the repeatability was therefore 99.7%.
The average standard deviation of the control samples in 4 different test runs was 0.52 log2, which is slightly more than half a dilution step. Titres were therefore reproducible on average with a range of plus or minus half a dilution step.
In cattle, 135 out of 916 herds with occurrence of malformations (14.7%) were confirmed infected with SBV by RT-PCR. In infected herds, 99.3% of the cows tested positive in the VNT, while 95.3% were seropositive in suspect herds (Table 2).
Table 2 Result of a serological field study in cattle, sheep and goat herds, carried out with the VNT
In sheep, 79 out of 259 herds with occurrence of malformations (30.5%) were confirmed infected with SBV by RT-PCR. In infected herds, 94.5% of the ewes tested positive in the VNT, while 90.6% were seropositive in suspect herds.
In goats, fewer cases of malformations were reported and investigated, and in 3 out of 30 herds (10%) SBV was confirmed by RT-PCR. Two out of three does tested in these infected herds were positive in the VNT. In suspect herds, 40% of the does tested positive in the VNT.
A very robust VNT was developed with a very high specificity and sensitivity, both close to 100%, in sheep and cattle. The assay was shown to be highly repeatable and reproducible. The VNT is easy to perform and can be read macroscopically as a result of the amido black staining. With the current, optimized protocol, this staining results most of the times in a very sharp transition between wells with and without CPE. This makes it easy and very fast to read the plates, with a high reliability and reproducibility. A serum control for each individual sample was not included during our evaluation of the test. No evidence for a toxic effect of serum on the cells was ever noticed, but to avoid false negative results, routine use of a serum control could be considered.
In infected herds, i.e. confirmed by RT-PCR, more than 94% of the sheep and 99% of the cows tested seropositive. The ewes and cows tested were sampled because of congenitally malformed offspring. In lambs, approximately 30% of these malformations were confirmed to be positive for SBV by RT-PCR on brain tissue. However, in many cases it was not possible to trace the confirmed SBV-positive lambs back to the exact mother, so the serum blood sample was sometimes obtained from other ewes in the herd. Nevertheless, more than 94% of these ewes tested seropositive, suggesting that at least within these sheep herds with congenital malformations, the infection is widespread with a high within-herd seroprevalence.
Calves with malformations, on the other hand, could usually be traced back to the mother and from these cows serum blood samples were collected for serology. More than 99.3% of these mothers were seropositive. These cattle sera originated from cows that gave birth to malformed calves that were positive in the RT-PCR for SBV and are currently the most well-defined serum samples from previously infected animals. The sensitivity of the VNT can be estimated most reliably from these samples and is therefore >99%, which is in line with the estimation during the initial evaluation of the test, based on the distribution of titres in a smaller set of field samples.
In suspect herds, SBV was not confirmed by RT-PCR and in some cases RT-PCR was not carried out at all. It is likely that the virus, after infecting the foetus and causing the malformations, was cleared during the last part of the gestation period, at least from the brain, which was the most common sampling site. The fact that calves were more often RT-PCR negative than lambs can then be explained by the longer gestation period in cows and supports this explanation. The fact that seroprevalences in suspect herds were slightly lower than in infected herds, suggests that also malformed offspring with defects unrelated to a SBV infection were submitted for testing. Given the high alertness for congenital malformations, this can be expected to happen. In any case it shows that serological assays are needed to reliably detect infections.
High seroprevalences, both on a regional level, but also within herds, with and without obvious clinical signs, are not uncommon for viruses related to SBV. In Australia, seroprevalence studies into the related Akabane virus (AKAV), revealed within-herd seroprevalences of 77% in 1964[8], up to 89% in 1971[9] and 99% in 1988 in the New South Wales area[10]. Furthermore, in Japan, 74% of apparently healthy cattle cohabitated with cows showing clinical signs from an AKAV infection were seropositive also[11]. Finally, a very high seroprevalence is reported in the Netherlands, both within the Netherlands as a whole as in a few individual herds[12].
In goats the number of seropositive animals is far lower than in sheep and cattle, although less samples from goats were tested and the estimated seroprevalence is therefore less precise. Most of the malformations in goats therefore likely had another cause, as no infection with SBV could be proven in most of the mothers of the affected kids, neither by RT-PCR, nor by serology. Probably these affected kids were submitted and tested for SBV due to the ongoing outbreak and the high alertness for congenital malformations. These results may reflect a lower seroprevalence in goats in general. Given that goats, in contrast to cattle and sheep, are often housed indoors, and the SBV is supposedly transmitted by Culicoides vectors, like other viruses of the Simbu serogroup[2, 13, 14], this lower seroprevalence would not be surprising.
Many countries outside the EU have closed their borders for cattle and sheep from SBV infected countries. Importing countries may require testing of animals originating from infected countries, which could include RT-PCR and/or serological testing. Although ELISA's are being developed, and one became recently available on the market, the VNT that was developed, is a possible alternative. It is easy to carry out, and even though the incubation period is quite long with 5 days, hands-on time is relatively short. This means that the VNT is relatively cheap, and the total test capacity for an average laboratory to carry out the VNT could be quite high. Depending on the number of dilutions to be tested, whether samples will be tested in duplicate or not, and based on existing experience and logistics within a laboratory, thousands of samples could be tested per week. Costs of the VNT are mainly related to labour, while costs of an ELISA are for a large part expenditures on materials. Furthermore, the VNT could be used as a confirmation test and probably even a gold standard if further evaluated and validated. For (semi)quantitative studies, either in animal experiments or field studies, a VNT also has its advantages.
A very robust VNT was developed with a very high specificity and sensitivity, both close to 100%, in sheep and cattle. The assay was shown to be highly repeatable and reproducible. The VNT is easy to perform and can be read macroscopically as a result of the amido black staining. As such it can be used as a confirmation test for commercially available enzyme-linked immunosorbent assays (ELISA's) and for (relative) quantification of antibodies, but also at a relative high throughput for testing of animals for export, surveillance, screening and research purposes.
Hoffmann B, Scheuch M, Höper D, Jungblut R, Holsteg M, Schirrmeier H, Eschbaumer M, Goller KV, Wernike K, Fischer M, Breithaupt A, Mettenleiter TC, Beer M: Novel orthobunyavirus in Cattle, Europe, 2011. Emerg Infect Dis. 2012, 18: 469-472. 10.3201/eid1803.111905.
Causey OR, Kemp GE, Causey CE, Lee VH: Isolations of Simbu-group viruses in Ibadan, Nigeria 1964–69, including the new types Sango, Shamonda, Sabo and Shuni. Ann Trop Med Parasitol. 1972, 66: 357-362.
Muskens J, Smolenaars AJ, van der Poel WH, Mars MH, van Wuijckhuise L, Holzhauer M, van Weering H, Kock P: Diarrhea and loss of production on Dutch dairy farms caused by the Schmallenberg virus [Diarree en productiedaling op Nederlandse melkveebedrijven door het Schmallenbergvirus]. Tijdschr Diergeneeskd. 2012, 137: 112-115.
Van Den Brom R, Luttikholt SJ, Lievaart-Peterson K, Peperkamp NH, Mars MH, Van Der Poel WH, Vellema P: Epizootic of ovine congenital malformations associated with Schmallenberg virus infection. Tijdschr Diergeneeskd. 2012, 137: 106-111.
ProMED-mail: Schmallenberg virus - Europe (01). Netherlands, update. Archive Number: 201201030019http://wwwpromedmailorg Accessed 22 February 2012 Published Date: 2012-01-03,
ProMED-mail: Schmallenberg virus - Europe (02). Update, RFI. Archive Number: 201201071002681http://wwwpromedmailorg Accessed 22 February 2012 Published Date: 2012-01-07,
Reed LJ, Muench H: A simple method of estimating fifty percent endpoints. Am J Hyg. 1938, 27: 493-497.
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Doherty RL, George TD, Carley JG: Arbovirus infections of sentinel cattle in Australia and New Guinea. Aust Vet J. 1973, 49: 574-579. 10.1111/j.1751-0813.1973.tb06737.x.
Jagoe S, Kirkland PD, Harper PA: An outbreak of Akabane virus-induced abnormalities in calves after agistment in an endemic region. Aust Vet J. 1993, 70: 56-58. 10.1111/j.1751-0813.1993.tb15139.x.
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Elbers ARW, Loeffen WLA, Quak S, de Boer-Luijtze E, Van Der Spek AN, Bouwstra R, Maas R, Spierenburg MAH, De Kluijver EP, Van Schaik G, Van der Poel WHM: Seroprevalence of Schmallenberg Virus antibodies among dairy cattle, the Netherlands, winter 2011–2012. Emerg Infect Dis. 2012, 18:
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Hendrik-Jan Roest, Miriam Koene and Aldo Dekker (CVI) are thanked for generously providing negative validation sera; Renate Hakze-van der Honing for assistance in isolating and growing the virus. Mieke Maris (CVI) is thanked for collecting sera from suspect and infected farms (positive field sera for validation) and propagation of the virus; DSU and the Virological Diagnostic Laboratory for assistance in the large test runs for the validation; Frans Verburgh for selecting all the relevant samples from the laboratory management system. This study was commissioned and funded by the Dutch Ministry of Economic Affairs, Agriculture, and Innovation.
Department of Virology, Central Veterinary Institute of Wageningen, University and Research Centre (CVI-Lelystad), P.O. Box 65, 8200 AB, Lelystad, The Netherlands
Willie Loeffen
, Sjaak Quak
, Els de Boer-Luijtze
, Wim van der Poel
, Ruth Bouwstra
& Riks Maas
Livestock Research of Wageningen, University and Research Centre, P.O. Box 65, 8200AB, Lelystad, The Netherlands
Marcel Hulst
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Correspondence to Willie Loeffen.
WL, SQ, EB and RM designed the study. SQ and EB carried out all the laboratory work. MH isolated and propagated the virus. WL compiled the results, analysed the data and wrote the manuscript. All authors were involved in the interpretation of results and have given helpful advice in writing the paper. All authors read and approved the final manuscript.
Loeffen, W., Quak, S., de Boer-Luijtze, E. et al. Development of a virus neutralisation test to detect antibodies against Schmallenberg virus and serological results in suspect and infected herds. Acta Vet Scand 54, 44 (2012) doi:10.1186/1751-0147-54-44
DOI: https://doi.org/10.1186/1751-0147-54-44
Neutralisation test
Seroprevalence
Submission enquiries: [email protected]
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Balakrishnan Ramasamy, Madhavi Karri, Sandhya Venkat, Andhuvan G.
Background: Primary headache disorders are among the most ubiquitous disorders affecting people worldwide. Migraine headache is one of the commonest syndromes of primary headache. There are few studies regarding clinical profile of migraine and migraine triggers in India. The objective this study was to study the gender, age distribution, frequency, severity of migraine attacks and other associated symptoms in patients presenting with migraine. To study in detail about triggers of migraine in present study population.
Methods: About 222 patients who presented with history suggestive of migraine with or without aura defined according to International classification of headache disorders 2, fulfilling the study criteria were included. The study duration was fifteen months from March 2017 to May 2018. Details were collected using a proforma.
Results: In this study, incidence of Migraine is higher in females (169,76%) than males (53, 24%). Majority of migraine patients were between age group of 18-29 years constituting about 77 patients (34.65%). Frequency of migraine more commonly observed was 3-4 per month was observed in 64 patients (29%) and chronic migraine was seen in 19 patients (8.4%). Migraine without aura is most common type observed in this study. Many patients had more than one trigger. More common triggers identified were sun exposure (85, 38.3%), sleep deprivation (83, 37.4%), stress (84, 37.8%) and travel (80, 36%).
Conclusions: Migraine is more common in females than males with majority being in between age group of 18-29 years. Many had frequency of 3-4 episodes per month. Most had more than one trigger.
Charles A. Clinical Practice N Engl J Med. 2017;377:553-61.
Goadsby PJ. Migraine: diagnosis and management. Int Med J. 2003;33(9‐10):436-42.
Charles A. The pathophysiology of migraine: implications for clinical management. Lancet Neur. 2018;17(2):174-82.
Dodick DW. Seminar Migraine. Lancet 2018;391:1315-30.
Panda S, Tripathi M. Clinical profile of migraineurs in a referral centre in India. JAPI. 2005;53:111-5.
Jena SS, Jena M, Dash M, Mishra S, Behera IC. Migraine: pattern of prescription and adverse drug reaction profile in a tertiary care teaching hospital. J Pharm Sc Res. 2015;7(3):111.
Okumura T, Tanno S, Ohhira M, Tanno S, Nozu T. Characteristics in patients with headache in an outpatient clinic in Japan. Asia Pacific Family Med. 2010;9(1):10.
Madsen TE, Howard VJ, Jiménez M, Rexrode KM, Acelajado MC, Kleindorfer D, et al. Impact of conventional stroke risk factors on stroke in women: an update. Stroke. 2018;49(3):536-42.
Kulkarni G, Rao G, Gururaj G, Subbakrishna DK, Steiner T, Stovner LJ. EHMTI-0333. The prevalence and burden of migraine in india: results of a population-based study in Karnataka state. J Headache Pain. 2014;15(1):B18.
Cheng X. Epidemiologic survey of migraine in six cities of China. Chinese J Neuro Psychia. 1990;23(1):44-6.
Zhao F, Tsay JY, Cheng XM, Wong WJ, Li SC, Yao SX, et al. Epidemiology of migraine: a survey in 21 provinces of the People's Republic of China, 1985. Headache: J Head Face Pain. 1988;28(8):558-65.
Wong TW, Wong KS, Yu TS, Kay R. Prevalence of migraine and other headaches in Hong Kong. Neuroepidemiol. 1995;14(2):82-91.
Ray BK, Paul N, Hazra A, Das S, Ghosal MK, Misra AK, et al. Prevalence, burden, and risk factors of migraine: A community-based study from Eastern India. Neuro India. 2017;65(6):1280.
Lipton RB, Silberstein SD. Why study the comorbidity of migraine?. Neurol. 1994.
Bera SC, Khandelwal SK, Sood M, Goyal V. A comparative study of psychiatric comorbidity, quality of life and disability in patients with migraine and tension type headache. Neurol India. 2014;62(5):516.
Agarwal V, Chaurasia R, Mishra VN, Joshi D, Misra S. Clinical profile of headache from a tertiary care Centre in eastern India. Int J Gen Med Pharma. 2013;2(3):9-14.
Bhatia MS, Gupta R. Migraine: Clinical pattern and psychiatric comorbidity. Ind Psychiatry J. 2012;21:18-21.
Ravishankar K. Migraine-the new understanding. J Assoc Physic India. 2010;58:30-3.
Turner LC, Molgaard CA, Gardner CH, Rothrock JF, Stang PE. Migraine trigger factors in a non‐clinical Mexican‐American population in San Diego county: implications for etiology. Cephalal. 1995;15(6):523-30.
Yadav RK, Kalita J, Misra UK. A study of triggers of migraine in India. Pain Medicine. 2010;11(1):44-7.
Hauge AW, Kirchmann M, Olesen J. Trigger factors in migraine with aura. Sage J. 2010;30(3):346-53.
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The Effect of Black Seed Oil as Adjuvant Therapy on Nuclear Factor Erythroid 2-Related Factor 2 Levels in Patients with Metabolic Syndrome Risk
Rahmat A Hi Wahid 1
Endang Darmawan 2
1 Department of Pharmacy, Faculty of Science and Technology, Universitas PGRI Yogyakarta, Yogyakarta, Indonesia
2 Department of Clinical Pharmacy, Faculty of Pharmacy, Universitas Ahmad Dahlan, Yogyakarta, Indonesia
Nuclear factor erythroid 2-related factor 2 (Nrf2) is one of the transcription factors involved in providing endogenous antioxidants. Black seed oil (BSO), suspected have antioxidant effects that can be used to modulate the expression and levels of Nrf2. The study aims to determine the effect of BSO as adjuvant therapy on levels of Nrf2 to the patients with metabolic syndrome risk.
The research used analytical observational with cohort design. Samples study consisted of 62 patients at risk with metabolic syndrome risk at Jetis I Public Health Center, Bantul District, from September to December 2016. Eligible subjects were divided into two groups, (1) BSO group, patients get BSO with a dose of 3 mL/day and standard therapy for 20 days. (2) Control group, patients got placebo and standard therapy during the intervention for 20 days. Level of Nrf2 were estimates using enzyme-linked immunosorbent assay (ELISA) method. The mean values ± SD between groups were tested with independent t-test with significance of p= The results showed that Nrf2 in group 1 was 0,866 ± 0,11 ng/ml and the group 2 was 0,864 ± 0,15 ng/mL (p=0,94). There were no significant difference in the both groups (p>0.05).
In conclusion, adjuvant therapy of BSO doses 3 mL/day for 20 days could not increase levels of Nrf2 in the patients with metabolic syndrome risk based on type treatment and demographic characteristic at Jetis I Public Health Center, Bantul District.
Black seed oil (BSO)
Indonesia Public Health Center
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[21] Kundu J.,Kim Hee Do.,Kundu,K.J., Chun, Soo-Kyung. Thymoquinone Induces Heme Oxygenase-1 Expression in HaCaT Cells Via Nrf2/ARE Activation: Akt and AMPKα as Upstream Targets. Food Chem. Toxicol. (2014) 65: 18-26.
[22] Ariani, N., Akrom, Darmawan, E. Kadar NDA (Malondialdehi) dan Ekspresi Gen Nrf2 (Nuclear Erythroid P45-Related Factor 2) pada Relawan Sehat yang Diberi MBJH (Minyak Biji Jinten Hitam). Thesis. PFakultas Farmasi. Universitas Ahmad Dahlan: Yogyakarta (2015).
[23] Gore R.P.,Prajapati P.C.,Mahajan B.U et al.,Protective Effect to Thymoquinone against Cyclophosphamide-Induced Hemorrhagic Cystitis through Inhibiting DNA Damage and Upregulation of Nrf2 Expression. Int. J. Biol. Sci. (2016) 12: 944-953.
[24] Darmawan, E. Imunax Development as an Immunomodulatory Antioxidant in Complementary Therapies for Metabolic Syndrome. Report on Grant Research Implementation. Faculty of Pharmacy.Universitas Ahmad Dahlan:. Yogyakarta (2016).
[25] Akrom, A., Darmawan, E., et al. Phase 2 Imunax@ Clinical Trial as an Antioxidant Immunomodulator in Patients with Metabolic Syndrome (2016).
[26] Jiménez-Osorio, Angélica S., et al. Nrf2 and Redox Status in Prediabetic and Diabetic Patients. Int. J. Mol. Sci. (2014) 15 (11): 20290-20305.
[27] Siewert, Susana, et al. Downregulation of Nrf2 and HO-1 Expression Contributes to Oxidative Stress in Type 2 Diabetes Mellitus: A study in Juana Koslay City, San Luis, Argentina. Int. J. Diabetes Mellit. (2013) 3 (2): 71-78.
[28] Khader M., Eckl PM. Thymoquinone: An Emerging Natural Drug with A Wide Range of Medical Applications. Iran. J. Basic Med. Sci. (2014): 950-957.
[29] Hao, Y.F., Long, C., Hui, Y.C., Hong, X.S. Effects of Thymoquinone on Oxidative stress and Cytokine Expression in Brain of Type 2 Diebetics Rats, Fudan Univ. J. Medical Sci. (2017) 44 (4): 483-488.
[30] Bhakkiyalakshmi, E., Sireesh, D., Rajaguru, P., Paulmurugan, R., & Ramkumar, K. M. The Emerging Role of Redox-Sensitive Nrf2–Keap1 Pathway in Diabetes. Pharmacol. Res. (2015) 91: 104-114.
[31] Li, B., Liu, S., Miao, L., & Cai, L. Prevention of Diabetic Complications by Activation of Nrf2: Diabetic Cardiomyopathy and Nephropathy. Exp. Diabetes Res. (2012) 2012: 216512.
[32] Jiang, T., Huang, Z., Lin, Y., Zhang, Z., Fang, D., & Zhang, D. D. The Protective Role of Nrf2 in Streptozotocin-Induced Diabetic Nephropathy. Diabetes (2010) 59 (4): 850-860.
[33] David, J. A., Rifkin, W. J., Rabbani, P. S., & Ceradini, D. J. The Nrf2/Keap1/ARE Pathway and Oxidative Stress as a Therapeutic Target in Type II Diabetes Mellitus. J. Diabetes Res. (2017) 2017: 4826724.
Wahid, R., & Darmawan, E. (2020). The Effect of Black Seed Oil as Adjuvant Therapy on Nuclear Factor Erythroid 2-Related Factor 2 Levels in Patients with Metabolic Syndrome Risk. Iranian Journal of Pharmaceutical Sciences, 16(1), 9-18. doi: 10.22034/ijps.2019.94568.1484
Rahmat A Hi Wahid; Endang Darmawan. "The Effect of Black Seed Oil as Adjuvant Therapy on Nuclear Factor Erythroid 2-Related Factor 2 Levels in Patients with Metabolic Syndrome Risk". Iranian Journal of Pharmaceutical Sciences, 16, 1, 2020, 9-18. doi: 10.22034/ijps.2019.94568.1484
Wahid, R., Darmawan, E. (2020). 'The Effect of Black Seed Oil as Adjuvant Therapy on Nuclear Factor Erythroid 2-Related Factor 2 Levels in Patients with Metabolic Syndrome Risk', Iranian Journal of Pharmaceutical Sciences, 16(1), pp. 9-18. doi: 10.22034/ijps.2019.94568.1484
Wahid, R., Darmawan, E. The Effect of Black Seed Oil as Adjuvant Therapy on Nuclear Factor Erythroid 2-Related Factor 2 Levels in Patients with Metabolic Syndrome Risk. Iranian Journal of Pharmaceutical Sciences, 2020; 16(1): 9-18. doi: 10.22034/ijps.2019.94568.1484
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Sci Rep. 2017 May 26;7(1):2452. doi: 10.1038/s41598-017-02706-z.
Quantification of hepatocellular carcinoma heterogeneity with multiparametric magnetic resonance imaging.
Hectors SJ1,2, Wagner M1,2,3, Bane O1,2, Besa C1,2, Lewis S1,2, Remark R4, Chen N1,2, Fiel MI5, Zhu H5, Gnjatic S6, Merad M4, Hoshida Y7, Taouli B8,9.
Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Sorbonne Universités, UPMC, Department of Radiology, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.
Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Oncological Science, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Department of Medicine/Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States. [email protected].
Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States. [email protected].
Tumour heterogeneity poses a significant challenge for treatment stratification. The goals of this study were to quantify heterogeneity in hepatocellular carcinoma (HCC) using multiparametric magnetic resonance imaging (mpMRI), and to report preliminary data correlating quantitative MRI parameters with advanced histopathology and gene expression in a patient subset. Thirty-two HCC patients with 39 HCC lesions underwent mpMRI including diffusion-weighted imaging (DWI), blood-oxygenation-level-dependent (BOLD), tissue-oxygenation-level-dependent (TOLD) and dynamic contrast-enhanced (DCE)-MRI. Histogram characteristics [central tendency (mean, median) and heterogeneity (standard deviation, kurtosis, skewness) MRI parameters] in HCC and liver parenchyma were compared using Wilcoxon signed-rank tests. Histogram data was correlated between MRI methods in all patients and with histopathology and gene expression in 14 patients. HCCs exhibited significantly higher intra-tissue heterogeneity vs. liver with all MRI methods (P < 0.030). Although central tendency parameters showed significant correlations between MRI methods and with each of histopathology and gene expression, heterogeneity parameters exhibited additional complementary correlations between BOLD and DCE-MRI and with histopathologic hypoxia marker HIF1α and gene expression of Wnt target GLUL, pharmacological target FGFR4, stemness markers EPCAM and KRT19 and immune checkpoint PDCD1. Histogram analysis combining central tendency and heterogeneity mpMRI features is promising for non-invasive HCC characterization on the imaging, histologic and genomics levels.
Histopathology processing of HCC sections obtained from a 70-year-old male patient with NASH cirrhosis and HCC. Zoomed microscopy images (×20) of an HCC section stained using Multiplexed Immunohistochemical Consecutive Staining on Single Slide (MICSSS) for CD3, CD31 and CD68 and a separate section stained for HIF1α are shown in the top row. Results of the automatic segmentation algorithm are shown in the bottom row, in which pixels identified as stained are coloured in red. CD3 = cluster of differentiation 3, CD31 = cluster of differentiation 31, CD68 = cluster of differentiation 68, HIF1α = hypoxia-inducible factor 1-alpha.
54 year-old male patient with cirrhosis secondary to chronic hepatitis B virus infection and HCC. (a) Representative magnified parametric maps of a large (8.3 cm) HCC. Location of the tumour within the liver is indicated by the white arrow on the T2-weighted image (bottom row, right). A distinct region in the anterior portion of the tumour of high arterial flow (Fa) and low R2* was observed, reflective of high tumour perfusion and normoxia (grey arrow in Fa and R2* pre O2 maps). The posterior portion of the tumour displays low Fa and high R2*, suggestive of poor perfusion and hypoxia (white arrow in Fa and R2* pre O2 maps). (b) Histograms of Fa, R2* pre O2, R1 pre O2 and ADC in the same lesion. The extensive heterogeneity observed in the parameter maps of Fa and R2* pre O2 is also reflected in the histograms, as illustrated by the fat tails and pronounced skewness, indicated by arrows. The R1 pre O2 histogram also exhibited skewness (black arrow). ADC = apparent diffusion coefficient, ART = arterial fraction, DV = distribution volume, Fa = arterial flow, Fp = portal flow, Ft = total flow, MTT = mean transit time, R1 = longitudinal relaxation rate, R2* = transverse relaxation rate.
Inter-tumour variability in MRI parameters. Absolute coefficients of variation (CV) of mean, median, SD, kurtosis and skewness parameter values across 39 HCC tumours (in 32 patients). Kurtosis and skewness showed a substantially higher inter-tumour variability compared to mean and median values. ADC = apparent diffusion coefficient, ART = arterial fraction, DV = distribution volume, Fa = arterial flow, Fp = portal flow, Ft = total flow, MTT = mean transit time, R1 = longitudinal relaxation rate, R2* = transverse relaxation rate.
Heatmaps of correlations between mean, median, SD, kurtosis and skewness of MRI parameters in 39 HCC lesions (in 32 patients). Significant correlations (P < 0.05) are coloured according to the scale bar. The correlation between R1 pre and post O2 and DCE-MRI parameters was not assessed, because the baseline R1 measurements were used as input for the DCE-MRI modelling. A combined heatmap of all significant correlations between MRI features is shown on the right, illustrating additional information provided by heterogeneity parameters (SD, kurtosis and skewness). Significant correlations between DCE-MRI and BOLD were for example only seen for heterogeneity parameters and not for central tendency parameters (mean and median). ADC = apparent diffusion coefficient, ART = arterial fraction, DV = distribution volume, Fa = arterial flow, Fp = portal flow, Ft = total flow, MTT = mean transit time, R1 = longitudinal relaxation rate, R2* = transverse relaxation rate.
Heatmaps of correlations between MRI parameters and histopathology in 14 HCC lesions in 14 patients. Significant correlations (P < 0.05) are coloured according to the scale bar. A combined heatmap of all significant correlations between MRI features and histopathology is shown on the right, illustrating additional information provided by heterogeneity parameters (SD, kurtosis and skewness). For example, HIF1α tumour fractions correlated with heterogeneity parameters, but not with central tendency parameters (mean and median). ADC = apparent diffusion coefficient, ART = arterial fraction, CD3 = cluster of differentiation 3, CD31 = cluster of differentiation 31, CD68 = cluster of differentiation 68, DV = distribution volume, Fa = arterial flow, Fp = portal flow, Ft = total flow, HIF1α = hypoxia-inducible factor 1-alpha, MTT = mean transit time, R1 = longitudinal relaxation rate, R2* = transverse relaxation rate.
Heatmaps of correlations between MRI parameters and gene expression levels in 14 HCC lesions in 14 patients. Significant correlations (P < 0.05) are coloured according to the scale bar. A combined heatmap of all MRI features is shown at the figure bottom, illustrating additional information provided by heterogeneity parameters (SD, kurtosis and skewness) compared to central tendency parameters (mean and median) with respect to correlations between MRI and gene expression levels. ADC = apparent diffusion coefficient, ART = arterial fraction, BIRC5 = Baculoviral IAP repeat containing 5, CD274 = cluster of differentiation 274, CTLA4 = cytotoxic T-lymphocyte-associated protein 4, DV = distribution volume, EPCAM = epithelial cell adhesion molecule, EZH2 = enhancer of zeste homolog 2, Fa = arterial flow, FGFR4 = fibroblast growth factor receptor 4, Fp = portal flow, Ft = total flow, GLUL = glutamate-ammonia ligase, HSP70 = 70 kilodalton heat shock protein, KRT19 = keratin 19; LYVE1 = lymphatic vessel endothelial hyaluronan receptor 1, MTT = mean transit time, R1 = longitudinal relaxation rate, R2* = transverse relaxation rate, VEGFA = vascular endothelial growth factor A.
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This component of assessment will provide an opportunity to put into practice the implementation of HIA on a project of choice. You will need to identify a prospective real or fictitious case study for this assignment and it is preferable that this case be in your geographical area so that you will have some familiarity with the issues involved. A manual has been included that provides background and guidelines to assist students in the various stages of implementing an HIA. Worksheets are provided and should be incorporated to assist with the data collection, presentation, analysis and evaluation.
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The Clinician I position is responsible for the provision of direct counseling services to Hockanum Valley clients with a wide range of emotional disorders, mental illness and substance abuse problems, using brief, focused treatment. This position will also provide clinical consultation for the provision of psychiatric services at HVCC.
§ Provides excellent client service.
§ Assists with special projects required for department.
§ Performs other duties as assigned.
The duties listed above are intended only as illustrative of the various types of work that may be performed. The omission of specific statements of duties does not exclude them from the position if the work is similar or a logical assignment to the position.
MA/MSWMFT is required; LCSW, LMFT, LPC or other license strongly preferred.
Principles and techniques of interviewing, mental health diagnostic assessment and appropriate counseling methods along with strong clinical assessment skills.
Minimum one year of related experience is required.
Ability to work independently without direct supervision, in new and unpredictable circumstances.
Experience with provision of case formulation to develop focused, goal-oriented treatment related to client readiness and developmental level.
Work with a broad range of cultural and ethnic groups tactfully and effectively.
§ Proficiency in Microsoft Office Suite required.
groups, both professional and non-professional, co-workers, management personnel, and the public and/or disabled residents.
Ability to work in a fast-paced environment and juggle multiple priorities.
Able to think quickly, assess a situation and make a sound decision.
§ Solid written and verbal communication, listening, organization, presentation and priority setting skills.
§ Strong commitment to working within a team environment is required.
§ Ability to work independently is required.
§ Ability to relate well with people from diverse groups.
§ Ability to perform job with integrity and values consistent with the HVCC Mission.
§ Is frequently required to use hands to finger, handle, feel or operate objects, tools or controls; and reach with hands and arms.
§ Must be able to perform continuous bending, twisting, stooping, reaching and lifting of moderate to heavy weight material up to 10 lbs.
§ Vision abilities required by the job include close vision, distance vision, peripheral vision, depth perception and the ability to adjust focus.
Must be able to walk, sit and stand for extended periods during the work day.
HVCC is a private nonprofit human services agency located in Vernon, Connecticut. It is dedicated to meeting the needs of the residents of Vernon and the Tolland County area.
HVCC provides services to individuals and families in a manner which will promote independence while ensuring that basic needs are met regardless of ability to pay.
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I've been crunching the numbers myself for years. I've never been in any doubt about them, but it's nice to see confirmation in the literature. The largest homebirth study ever done shows that homebirth triples the rate of neonatal death.
Maternal and newborn outcomes in planned homebirth: a meta-analysis will be published in the September issue of the American Journal of Obstetrics and Gynecology. I was fortunate to obtain an advance copy. More than 342,000 homebirths were compared to more than 207,000 hospital births. The data was obtained by pooling 12 major studies from a variety of countries. These studies include the recent DeJonge study from The Netherlands and the Janssen study from Canada. There are also studies from the US, the UK, Australia and Sweden.
The 12 studies were culled from a search of the scientific literature comparing planned homebirth to hospital birth. Only those studies that used the intended place of birth, as opposed to the actual place of birth, are included. That's important because many homebirth studies look at actual place of birth and thereby include homebirth transfers in the hospital group, skewing the results.
Planned home births experienced significantly fewer medical interventions including epidural analgesia, electronic fetal heart rate monitoring, episiotomy, and operative vaginal and cesarean deliveries. Likewise, women intending home deliveries hadfewer infections, 3-degree lacerations [or greater], perineal and vaginal lacerations, hemorrhages, and retained placentas.
Of concern, this investigation identified a doubling and tripling of the neonatal mortality rate overall and among nonanomalous offspring, respectively, in planned home compared to planned hospital births. This finding is particularly robust considering the homogeneity of the observation across studies. It is especially striking as women planning home births were of similar and often lower obstetric risk than those planning hospital births. The planned home delivery group commonly exhibited fewer obstetric risk factors such as excessive body mass index, nulliparity, prior cesarean, and previous pregnancy complications.
Why was the neonatal death rate higher in the planned homebirth group?
… 2 cohort studies implicated intrapartum asphyxia in 31% and 52% of planned home delivery perinatal deaths. The past 2 decades have seen a significant decrease in such deaths, with evidence suggesting fewer fetuses experiencing intrapartum anoxia. Speculative explanations for the trend include more liberal use of ultrasound, electronic fetal heart rate monitoring, fetal acid-base assessment, labor induction, and cesarean delivery. Our findings, considered in light of these observations, raise the question of a link between the increased neonatal mortality among planned home births and the decreased obstetric intervention in this group.
I'd like to tell you that this study is rock solid, since it confirms what I have been writing for years. Unfortunately, the study has some serious flaws. First, it includes some data collected more than two decades ago. Second, it includes some papers that looked at very small numbers of births. Third, while it found a dramatically increased risk of neonatal mortality, it found no difference in perinatal mortality. This is not what we would expect if the excess deaths were due to intrapartum stillbirths or failed resuscitations.
The meta-analysis include two large studies from The Netherlands and Canada, both of which showed no difference in perinatal and neonatal mortality rates. The other 10 studies (from the US, the UK, Sweden and Australia) did show increased rates of perinatal and neonatal death. It seems to me that the take home message of the study is not that homebirth is unsafe, but that homebirth can only be safe when practiced by highly trained midwives, fully integrated into the hospital system in countries with strict criteria for homebirth and dedicated transport systems for emergencies. In other words, homebirth is safe in The Netherlands and Canada, but no where else.
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The association between hospital length of stay before rapid response system activation and clinical outcomes: a retrospective multicenter cohort study
Jimyung Park1 na1,
Yeon Joo Lee2 na1,
Sang-Bum Hong3,
Kyeongman Jeon4,5,
Jae Young Moon6,
Jung Soo Kim7,
Byung Ju Kang8,
Jong-Joon Ahn8,
Dong-Hyun Lee9,
Jisoo Park10,
Jae Hwa Cho11 &
Sang-Min Lee ORCID: orcid.org/0000-0002-1388-93181
Rapid response system (RRS) is being increasingly adopted to improve patient safety in hospitals worldwide. However, predictors of survival outcome after RRS activation because of unexpected clinical deterioration are not well defined. We investigated whether hospital length of stay (LOS) before RRS activation can predict the clinical outcomes.
Using a nationwide multicenter RRS database, we identified patients for whom RRS was activated during hospitalization at 9 tertiary referral hospitals in South Korea between January 1, 2016, and December 31, 2017. All information on patient characteristics, RRS activation, and clinical outcomes were retrospectively collected by reviewing patient medical records at each center. Patients were categorized into two groups according to their hospital LOS before RRS activation: early deterioration (LOS < 5 days) and late deterioration (LOS ≥ 5 days). The primary outcome was 28-day mortality and multivariable logistic regression was used to compare the two groups. In addition, propensity score-matched analysis was used to minimize the effects of confounding factors.
Among 11,612 patients, 5779 and 5883 patients belonged to the early and late deterioration groups, respectively. Patients in the late deterioration group were more likely to have malignant disease and to be more severely ill at the time of RRS activation. After adjusting for confounding factors, the late deterioration group had higher 28-day mortality (aOR 1.60, 95% CI 1.44–1.77). Other clinical outcomes (in-hospital mortality and hospital LOS after RRS activation) were worse in the late deterioration group as well, and similar results were found in the propensity score-matched analysis (aOR for 28-day mortality 1.66, 95% CI 1.45–1.91).
Patients who stayed longer in the hospital before RRS activation had worse clinical outcomes. During the RRS team review of patients, hospital LOS before RRS activation should be considered as a predictor of future outcome.
A rapid response system (RRS) is a system designed for prompt and appropriate intervention in patients who experience unexpected clinical deterioration during hospitalization [1]. Previous studies have shown its efficacy in reducing the rates of in-hospital mortality, and the implementation of RRS has been increasing worldwide in recent decades [2, 3]. Therefore, accurate risk stratification is needed for improving the triage of patients and resource allocation. However, despite the pervasive use of RRS, little is known about how best to predict the clinical outcomes of patients for whom RRS is activated. A recent study using multicenter registry data reported that, in addition to vital signs such as systolic blood pressure and respiratory rate, time after admission before RRS activation is a significant predictor of mortality [4].
Hospital length of stay (LOS) is often used as one method for assessing patient outcomes in clinical practice. It is well known that a longer hospital LOS is associated with a higher risk of malnutrition and frailty [5, 6]. In addition, older patients with poor baseline functional status are more likely to stay longer after various elective surgeries because of postoperative complications [7]. Considering that RRS activation occurs in the middle of hospitalization while patients are being actively treated, hospital LOS before RRS activation may provide a simple substitute marker for estimating the effectiveness of past treatments and predicting future outcomes. In this study, using a large nationwide multicenter database of patients reviewed by RRS teams, we aimed to evaluate whether hospital LOS before RRS activation can predict the clinical outcomes of patients after adjusting for confounding factors associated with the severity of illness.
We retrospectively analyzed the medical records of patients for whom an RRS call was activated in 9 tertiary referral hospitals in South Korea between January 1, 2016, and December 31, 2017. Patients older than 18 years for whom RRS was activated during hospitalization were eligible for this study and screened using the RRS database for each center. We included every eligible patient whose time after admission before RRS activation was ≤ 1 month. If there were recurrent RRS calls in one patient, the first circumstance of RRS activation was included in the analysis of this study. The study protocol was reviewed and approved by the institutional review board of each center and informed consent was waived.
Implementation of RRS
Although the detailed protocols of RRS differed between centers, all centers used the vital signs or certain laboratory results for in-ward patients to screen and identify patients at risk of clinical deterioration. In addition, calls from medical staff members on the ward, including doctors and nurses, were also used to identify patients whose clinical situation was worsening, even if they did not meet the specific activation criteria, and the RRS team was dispatched if needed. The detailed RRS activation criteria are summarized in the Additional file 1: Appendix S1.
Study outcomes and data collection
The primary outcome of our study was 28-day mortality. For secondary outcomes, we evaluated in-hospital mortality, admission to the intensive care unit (ICU), hospital LOS after RRS activation, and LOS in the ICU for patients admitted to the ICU. Data were collected retrospectively by reviewing patient medical records at each participating center. Detailed information regarding the situation when RRS was activated was collected. In addition to the interventions carried out by the RRS team, we also checked whether discussion of a do-not-resuscitate (DNR) order was made after RRS activation. The severity of illness at the time of RRS activation was evaluated, and the modified early weaning score (MEWS) and the national early warning score 2 (NEWS2) were calculated for each patient.
To evaluate the effects of hospital LOS before RRS activation on the clinical outcomes, we categorized the patients according to their days since admission before RRS activation. We divided patients into two groups (early deterioration vs. late deterioration groups) by dichotomizing hospital LOS before RRS activation with the median value. Differences between groups were analyzed using the Mann–Whitney U test or Pearson's chi-squared test, as appropriate. P values < 0.05 for two-tailed tests were considered to be statistically significant.
Mortality outcomes and rates of admission to the ICU were compared between the early and late deterioration groups using a multivariable logistic regression and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were calculated. We selected relevant clinical variables to adjust for that showed significant associations with mortality outcomes. Missing variables were handled with multiple imputation methods [8]. Outcomes related to LOS (hospital LOS after RRS activation and LOS in the ICU for patients admitted to the ICU) were analyzed using a negative binomial regression to calculate the adjusted incidence rate ratios (aIRRs).
Even after using multivariable regression models to compare clinical outcomes between the early and late deterioration groups, we expected some remaining confounding factors to be present because the two groups would be clinically different. Therefore, we performed propensity score-matched analysis to reduce the effects of possible confounding factors as much as possible [9]. After calculating propensity score (late vs. early deterioration), we conducted 1:1 optimal matching without replacement [10]. A more detailed description of the analysis is available in the Additional file 1: Appendix S2. Using matched samples, we calculated unadjusted and adjusted ORs to assess the associations between binary outcomes and LOS before RRS activation using a conditional logistic regression model for matched data [11, 12]. For continuous outcomes, the Wilcoxon signed-rank test was used to compare between matched samples.
We also performed several sensitivity analyses. First, we included the patients who were excluded in the main analysis because RRS was activated after 1 month of admission to evaluate whether our inclusion criteria affected the study results. Second, we conducted analysis with only patients without missing data to exclude possible bias due to the multiple imputation methods used to handle missing data. Third, patients in whom discussion on DNR orders occurred were excluded for the analysis. Fourth, the same analyses were repeated with handling hospital LOS as a continuous variable, instead of categorizing patients into early and late deterioration groups, to examine the robustness of our results. Fifth, we categorized patients into four quartile groups using the interquartile range (IQR) values for the hospital LOS before RRS activation. Then, we evaluated whether there was a proportional relationship between the LOS before RRS activation and mortality outcomes.
For the primary outcome (28-day mortality), prespecified subgroup analyses with tests for interactions were performed. We compared the effects of hospital LOS on the clinical outcomes between subgroups according to the patient's department of admission (medical vs. surgical) and whether the patient had undergone a surgical operation before RRS activation. In addition, we analyzed the subgroup of patients for whom RRS was activated through use of the screening criteria (i.e. not by calls from in-ward medical staff members). We also conducted subgroup analyses for three key comorbidities (solid cancer, hematological malignancy, and chronic lung disease). All statistical analyses were performed using STATA software (version 14.0; StataCorp LP, College Station, TX, USA).
During the 2-year study period, a total of 12,803 patients had RRS activation in 9 participating centers. Of these patients, 1191 were excluded because RRS activation occurred > 1 month after admission to the hospital and 11,612 patients were included in our analysis (Fig. 1). The excluded patients were younger and had lower BMI. They were also more likely to be admitted for surgical operation or hematological malignancy (Additional file 1: Table S1). The median number of days after admission before RRS activation was 5 (IQR 2–10) (Additional file 1: Fig. S1). Using a cutoff value of 5 days, we divided patients into two groups: an early deterioration group (LOS before RRS activation < 5 days, N = 5779) and a late deterioration group (LOS before activation ≥ 5 days, N = 5883).
Flowcharts of patients included in the study
The baseline characteristics were compared between these two groups and are summarized in Table 1. Patients in the early deterioration group were more likely to be admitted to a medical department than a surgical department, and significantly more patients in the late deterioration group underwent a surgical operation before RRS activation during their hospitalization. The comorbidities differed between the two groups. Particularly, malignant disease was more common in the late deterioration group, whereas chronic lung disease was more frequent in the early deterioration group.
Table 1 Patient characteristics
RRS activations
Information about the context of RRS is described in Additional file 1: Table S2. The most common assessment made by the RRS team was respiratory distress (35.1%). At the time of RRS activation, more severely ill patients were included in the late deterioration group. Hence, interventions delivered by the RRS team also differed between the two groups (Table 2). Notably, discussion on DNR orders occurred significantly more frequently in the late deterioration group.
Table 2 Severity of illness at RRS activation and interventions by RRS team
Outcomes in relation to the hospital LOS before RRS activation
Data on primary and secondary outcomes are summarized in Table 3. Overall, 2534 of 11,612 patients (21.8%) had died by 28 days after RRS activation: 1051 of 5779 patients (18.2%) in the early deterioration group and 1483 of 5833 patients (25.4%) in the late deterioration group (aOR 1.60; 95% CI 1.44–1.77). The effects of other adjusted variables are described in Additional file 1: Table S3. Similar results were observed in the analysis of in-hospital mortality with a higher mortality rate in the late deterioration group (20.9% vs. 30.2%, aOR 1.71; 95% CI 1.55–1.88). Other clinical outcomes (ICU admission, hospital LOS after RRS activation, and LOS in the ICU) were all worse in the late deterioration group.
Table 3 Effects of the hospital LOS before RRS activation on the clinical outcomes
Propensity score-matched analysis
Among these 10,149 patients who had no missing data for the prespecified variables for the propensity model, 4454 patients were 1:1 matched for each of the early and late deterioration groups. The distribution of the propensity scores in the two groups is depicted in Additional file 1: Fig S2. The matched groups were shown to be well balanced in baseline characteristics (Additional file 1: Table S4), except that more patients in the late deterioration group underwent a surgical operation during hospitalization before RRS activation (standardized difference 11.1%).
The results of analysis of the propensity score-matched samples are summarized in Table 4. The associations between mortality outcomes and hospital LOS before RRS activation were similar to those found in the unmatched analysis. The late deterioration group had a significantly higher rates of 28-day mortality (aOR 1.66; 95% CI 1.45–1.91) and in-hospital mortality (aOR 1.72; 95% CI 1.51–1.95), which showed similar aOR values as in the unmatched analysis.
Table 4 Analysis in the propensity score-based 1:1 matched patients
Several sensitivity analyses showed the robustness of the results of our main analysis (Additional file 1: Table S5–9). Particularly, when hospital LOS was handled as a continuous variable in the regression analysis, 1-day increase in hospital LOS was associated with worsening of all clinical outcomes, consistent with the results of main analysis. Then, we performed further analysis after dividing patients into four quartiles (Qs) according to their hospital LOS before RRS activation: Q1 (N = 2273, < 2 days); Q2 (N = 3506, 2–4 days); Q3 (N = 2620, 5–9 days); and Q4 (N = 3213, ≥ 10 days). Both aORs for 28-day mortality and in-hospital mortality showed an increasing tendency with longer hospital LOS before RRS activation (Fig. 2).
Adjusted odds ratio for 28-day mortality and in-hospital mortality according to quartile groups
Subgroup analysis
Prespecified subgroup and interaction-term analyses were performed to investigate possible effect modifiers (Fig. 3). There was a significant interaction between the department of admission (medical vs. surgical) and the effects of hospital LOS on 28-day mortality (P = 0.047 for interaction). The negative impact of longer hospital LOS before RRS activation was stronger for patients admitted to the surgical department. A similar interaction was also observed when comparing patients who underwent a surgical operation and those who did not (P = 0.006 for interaction). For other subgroup analyses, there were no significant between-group differences in the primary outcome.
Forest plot for predefined subgroup analysis
In this study, we found that longer hospital LOS before RRS activation was associated with worse clinical outcomes. Patients who stayed ≥ 5 days before RRS activation had higher 28-day and in-hospital mortality rates and were more likely to stay longer in the hospital after RRS activation compared with those who stayed < 5 days. This finding was robust after adjusting for variables reflecting the severity of illness at the time of RRS activation and even after propensity score-matched analysis.
The effectiveness of RRS has been studied extensively in the past two decades. Although early studies including cluster randomized trials failed to show significant reduction in mortality [13, 14], many other studies, such as before and after studies, have consistently shown positive results, as demonstrated in recent systematic review and meta-analysis studies [2, 15]. However, in real-world practice, when implementing RRS, it is difficult to predict clinical outcomes of individual patients for whom RRS activated because a wide range of patients with various comorbidities are being reviewed by the RRS team.
Certain alarming vital signs or laboratory test abnormalities are usually used as screening tools for RRS activation [16]. However, when two different patients with similar vital signs are reviewed by the RRS team, the expected outcomes may differ according to the patients' current illness and comorbidities. As the volume of cases reviewed by the RRS team increases, it is important to be able to predict the clinical outcome to improve the cost-effectiveness and optimize resource use. This also relates to the decision about which patients should be admitted to the ICU when available beds and resources are limited. Patients who have a higher probability of recovery are usually given a higher priority for ICU admission [17]. However, it is difficult for RRS staff members to review the functional status and detailed medical history of patients and assess the likelihood of recovery in a short time.
In this regard, attention has been focused on efforts to identify predictors of clinical outcomes for patients for whom RRS is activated. A prospective observational study reported that assessment of frailty would be helpful for predicting the clinical trajectory of patients [18]. We hypothesized that hospital LOS before RRS activation may be a useful and simple predictor of clinical outcome after considering that severe frailty is usually associated with longer LOS [5]. In two previous single-center studies that evaluated the effect of LOS before RRS activation on clinical outcomes, the late deterioration group (≥ 7 days) had more than twice the in-hospital mortality rate than the early deterioration group (< 2 days) [19, 20]. However, those studies did not fully adjust for between-group differences in their analyses.
A study using the nationwide multicenter registry in the USA, which included about 280,000 patients, demonstrated that hours since admission before RRS activation was the second most important factor, after systolic blood pressure, in predicting in-hospital mortality [4]. However, a limitation of that study was that patients' underlying comorbidities were categorized too simply as either medical or surgical and either cardiac or noncardiac. A detailed history of underlying comorbidities is a critical factor affecting the outcome, as shown in a recent study that reported an in-hospital mortality rate of > 40% in patients with hematological malignancy for whom RRS was activated [21].
In this study, we found that time since admission before RRS activation was an independent significant predictor of clinical outcome. A longer LOS before RRS activation itself may suggest ineffectiveness of the initial treatment and reflect the severity of the illness that caused the patient to be admitted. Therefore, among the patients with long hospital LOS at the time of RRS activation, invasive treatment, such as mechanical ventilation, may be deemed as futile in a certain proportion of patients. This is reflected by our finding that more patients in the late deterioration group had discussion with RRS staff members regarding the DNR order. Although attending physicians have a principal role in communicating with patients and their family members, the intervention of a third party, the RRS team, may improve end-of-life care planning by avoiding unnecessary or futile invasive treatment [22, 23].
The association between longer hospital LOS and worse clinical outcomes may indicate that medical problems acquired in the hospital setting are usually more serious, particularly for infectious complications [24]. This is because patients with hospital-acquired infection are at higher risk of infection with multidrug resistant pathogens. In our subgroup analysis, it was noted that the negative effects of longer hospital LOS on the clinical outcomes were more significant in patients who were admitted to surgical department or underwent a surgical operation. Given that postoperative wound infection or pneumonia are common problems leading to delay in discharge in surgical patients, these findings may be related to postoperative in-hospital infections due to difficult-to-treat pathogens [25].
Our study has several limitations. First, because of its retrospective observational design, we cannot exclude the possible effects of other unmeasured confounding factors. However, we found consistent results for the main analysis, propensity score-matched analysis, and several sensitivity analyses, which supports the robustness of our results. Second, we could not match every variable completely in our propensity score-matched analysis. Especially, the standardized difference between matched groups in the proportion of patients who underwent a surgical operation before RRS activation was 11.1%. Thus, we double adjusted the confounding variables to minimize the confounding effects [11]. Furthermore, we performed a subgroup analysis according to whether the patient received a surgery. Third, a causal relationship cannot be inferred between hospital LOS before RRS activation and later clinical outcomes. Despite these limitations, we believe that hospital LOS at the time of RRS activation may provide a simple and reliable prognostic information on future outcomes.
In conclusion, among patients for whom RRS was activated for unexpected clinical deterioration during hospitalization, those who stayed longer in the hospital before RRS activation had a higher mortality rate than those who stayed a shorter time. For improving resource allocation without undermining the probability of recovery, a careful review of the reversibility of the patients should be performed in patients with a long hospital LOS at the time of RRS activation.
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
DNR:
Do-not-resuscitate
IRR:
Incident rate ratio
ICU:
IQR:
Interquartile range
LOS:
MEWS:
Modified early weaning score
NEWS2:
National early warning score 2
RRS:
Rapid response system
Jones DA, DeVita MA, Bellomo R. Rapid-response teams. N Engl J Med. 2011;365(2):139–46.
Maharaj R, Raffaele I, Wendon J. Rapid response systems: a systematic review and meta-analysis. Crit Care. 2015;19:254.
Steel AC, Reynolds SF. The growth of rapid response systems. Jt Comm J Qual Patient Saf. 2008;34(8):489–95, 33.
Shappell C, Snyder A, Edelson DP, Churpek MM. American Heart Association's Get With the Guidelines-Resuscitation Investigators. Predictors of in-hospital mortality after rapid response team calls in a 274 hospital nationwide sample. Crit Care Med. 2018;46(7):1041–8.
Juma S, Taabazuing MM, Montero-Odasso M. Clinical frailty scale in an acute medicine unit: a simple tool that predicts length of stay. Can Geriatr J. 2016;19(2):34–9.
Kyle UG, Genton L, Pichard C. Hospital length of stay and nutritional status. Curr Opin Clin Nutr Metab Care. 2005;8(4):397–402.
Collins TC, Daley J, Henderson WH, Khuri SF. Risk factors for prolonged length of stay after major elective surgery. Ann Surg. 1999;230(2):251–9.
Little RJ, D'Agostino R, Cohen ML, Dickersin K, Emerson SS, Farrar JT, et al. The prevention and treatment of missing data in clinical trials. N Engl J Med. 2012;367(14):1355–60.
D'Agostino RB Jr. Propensity score methods for bias reduction in the comparison of a treatment to a non-randomized control group. Stat Med. 1998;17(19):2265–81.
Rosenbaum PR. Optimal matching for observational studies. J Am Stat Assoc. 1989;84(408):1024–32.
Nguyen TL, Collins GS, Spence J, Daures JP, Devereaux PJ, Landais P, et al. Double-adjustment in propensity score matching analysis: choosing a threshold for considering residual imbalance. BMC Med Res Methodol. 2017;17(1):78.
Pearce N. Analysis of matched case-control studies. BMJ. 2016;352:i969.
Chan PS, Khalid A, Longmore LS, Berg RA, Kosiborod M, Spertus JA. Hospital-wide code rates and mortality before and after implementation of a rapid response team. JAMA. 2008;300(21):2506–13.
Hillman K, Chen J, Cretikos M, Bellomo R, Brown D, Doig G, et al. Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial. Lancet. 2005;365(9477):2091–7.
Solomon RS, Corwin GS, Barclay DC, Quddusi SF, Dannenberg MD. Effectiveness of rapid response teams on rates of in-hospital cardiopulmonary arrest and mortality: a systematic review and meta-analysis. J Hosp Med. 2016;11(6):438–45.
DeVita MA, Smith GB, Adam SK, Adams-Pizarro I, Buist M, Bellomo R, et al. Identifying the hospitalised patient in crisis—a consensus conference on the afferent limb of rapid response systems. Resuscitation. 2010;81(4):375–82.
Nates JL, Nunnally M, Kleinpell R, Blosser S, Goldner J, Birriel B, et al. ICU admission, discharge, and triage guidelines: a framework to enhance clinical operations, development of institutional policies, and further research. Crit Care Med. 2016;44(8):1553–602.
So RKL, Bannard-Smith J, Subbe CP, Jones DA, van Rosmalen J, Lighthall GK, et al. The association of clinical frailty with outcomes of patients reviewed by rapid response teams: an international prospective observational cohort study. Crit Care. 2018;22(1):227.
Smith RJ, Santamaria JD, Faraone EE, Holmes JA, Reid DA, Tobin AE. The duration of hospitalization before review by the rapid response team: a retrospective cohort study. J Crit Care. 2015;30(4):692–7.
Medical Emergency Team End-of-Life Care investigators. The timing of rapid-response team activations: a multicentre international study. Crit Care Resusc. 2013;15(1):15–20.
Gershkovich B, Fernando SM, Herritt B, Castellucci LA, Rochwerg B, Munshi L, et al. Outcomes of hospitalized hematologic oncology patients receiving rapid response system activation for acute deterioration. Crit Care. 2019;23(1):286.
Downar J, Rodin D, Barua R, Lejnieks B, Gudimella R, McCredie V, et al. Rapid response teams, do not resuscitate orders, and potential opportunities to improve end-of-life care: a multicentre retrospective study. J Crit Care. 2013;28(4):498–503.
Downar J, Barua R, Rodin D, Lejnieks B, Gudimella R, McCredie V, et al. Changes in end of life care 5 years after the introduction of a rapid response team: a multicentre retrospective study. Resuscitation. 2013;84(10):1339–44.
Rosenthal VD, Guzman S, Orellano PW. Nosocomial infections in medical-surgical intensive care units in Argentina: attributable mortality and length of stay. Am J Infect Control. 2003;31(5):291–5.
Khan NA, Quan H, Bugar JM, Lemaire JB, Brant R, Ghali WA. Association of postoperative complications with hospital costs and length of stay in a tertiary care center. J Gen Intern Med. 2006;21(2):177–80.
This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HI18C0599).
Jimyung Park and Yeon Joo Lee contributed equally to this work
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea
Jimyung Park & Sang-Min Lee
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea
Yeon Joo Lee
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Sang-Bum Hong
Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
Kyeongman Jeon
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chungnam National University Sejong Hospital, Chungnam National University College of Medicine, Sejong-si, Republic of Korea
Jae Young Moon
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Inha University Hospital, Inha University School of Medicine, Incheon, Republic of Korea
Jung Soo Kim
Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
Byung Ju Kang & Jong-Joon Ahn
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Dong-A University College of Medicine, Busan, Korea
Dong-Hyun Lee
Division of Pulmonology, Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam-si, Korea
Jisoo Park
Division of Pulmonology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
Jae Hwa Cho
Jimyung Park
Byung Ju Kang
Jong-Joon Ahn
Sang-Min Lee
Sang-Min Lee was the study lead and guarantor for this paper. Jimyung Park, Yeon Joo Lee and Sang-Min Lee developed the study concept and protocol. Jimyung Park and Yeon Joo Lee, as co-first authors, performed the main data analysis and wrote the first draft of this manuscript. All the other authors were involved in the validated data collection, refinement of data analysis, and editing of the final version of this manuscript. All authors read and approved the final manuscript.
Correspondence to Sang-Min Lee.
This study was approved by institutional review board of each participating center. Informed consent was waived because this study was considered as posing minimal risk to the study participants because of its retrospective study design.
Additional file 1: Appendix S1.
RRS activation criteria of each center. Appendix S2. Supplemental methods. Table S1. Characteristics and outcomes of patients excluded in main analysis. Table S2. Information about situation when RRS was activated. Table S3. Full adjusted model for predicting 28-day mortality. Table S4. Characteristics of the propensity score-matched patients. Table S5. Outcome analysis with including all patients, not excluding those for whom RRS was activated after 1 month after admission. Table S6. Outcome analysis with patients without missing data. Table S7. Outcome analysis after excluding patients in whom discussion occurred regarding do-not-resuscitate orders. Table S8. Outcome analysis with handling hospital LOS before RRS activation as a continuous variable. Table S9. Outcome analysis based on categorizing patients into four quartiles according to LOS before RRS activation. Figure S1. Distribution of hospital length of stay before rapid response system activation. Figure S2. Propensity score distribution
Park, J., Lee, Y.J., Hong, SB. et al. The association between hospital length of stay before rapid response system activation and clinical outcomes: a retrospective multicenter cohort study. Respir Res 22, 60 (2021). https://doi.org/10.1186/s12931-021-01660-9
Hospital rapid response team
Clinical deterioration
General ward
Intensive care units
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Home › Products › Ion Channels › Gap Junction Channels › Pannexin Family › Antibodies
Guinea Pig Anti-Pannexin 1 Antibody
PANX1, PX1, MRS1, UNQ2529
Cat #: ACC-234-GP
Alternative Name PANX1, PX1, MRS1, UNQ2529
Host: Guinea Pig
Peptide (C)KEPTEPKFKGLRLE, corresponding to amino acid residues 18 - 31 of human PANX1 (Accession Q96RD7). Intracellular, N-terminus.
Homology Rat, mouse - identical.
Isotype Guinea pig total IgG
Reconstitution 25 µl, 50 µl or 0.2 ml double distilled water (DDW), depending on the sample size.
Preadsorption Control 1 µg peptide per 1 µg antibody
Pannexin 1 Blocking Peptide (#BLP-CC234)
Applications: ih, wb
May also work in: ic*, ip*
Western blot analysis of rat brain lysate (lanes 1 and 4), mouse brain lysate (lanes 2 and 5) and small intestine lysate (lanes 3 and 6):
1-3. Guinea Pig Anti-Pannexin 1 Antibody (#ACC-234-GP), (1:400).
4-6. Guinea Pig Anti-Pannexin 1 Antibody, preincubated with Pannexin 1 Blocking Peptide (#BLP-CC234).
Expression of Pannexin 1 in rat hippocampus.
Immunohistochemical staining of perfusion-fixed frozen rat brain sections with Guinea Pig Anti-Pannexin 1 Antibody (#ACC-234-GP), (1:300), followed by goat anti-guinea pig - Alexa Fluor-594. A. Staining in the rat hippocampal dentate gyrus region, showed Pannexin 1 immunoreactivity (red) in the granule layer (G) and in hilar interneurons (arrows). B. Pre-incubation of the antibody with Pannexin 1 Blocking Peptide (#BLP-CC234), suppressed staining. Cell nuclei are stained with DAPI (blue).
Expression of Pannexin 1 in mouse cerebellum.
Immunohistochemical staining of perfusion-fixed frozen mouse brain sections with Guinea Pig Anti-Pannexin 1 Antibody (#ACC-234-GP), (1:300), followed by goat anti-guinea pig - Alexa Fluor-594. A. Pannexin 1 immunoreactivity (red) appears in purkinje cells (arrows). B. Pre-incubation of the antibody with Pannexin 1 Blocking Peptide (#BLP-CC234), suppressed staining. Cell nuclei are stained with DAPI (blue).
Chew, S.S. et al. (2010) Exp. Neurol. 225, 250.
Nakagawa, S. et al. (2010) Curr. Opin. Struct. Biol. 20, 423.
Trexler, E.B. et al. (1996) Proc. Natl. Acad. Sci. U.S.A. 93, 5836.
Hu, X. et al. (2006) Biophys. J. 90, 140.
Shestopalov, V.I. and Panchin, Y. (2008) Cell. Mol. Life Sci. 65, 376.
Unger, V.M. et al. (1999) Science 283, 1176.
Falk, M.M. (2000) Eur. J. Cell. Biol. 79, 564.
Panchin, Y.V. (2005) J. Exp. Biol. 208, 1415.
Litvin, O. et al. (2006) J. Cell. Mol. Med. 10, 613.
Bruzzone, R. et al. (2003) Proc. Natl. Acad. Sci. U.S.A. 100, 13664.
Bravo, D. et al. (2015) Pharmacol. Res. 101, 86.
Gap junctions are usually found in clusters and enable intercellular communication by allowing the passage of small molecules between cells1. They play important roles in different biological processes. These include differentiation, cell cycle synchronization, cellular development, neuronal activity and the immune response2-4.
Proteins involved in gap junction formation are composed of four transmembrane domains, two extracellular loops and one intracellular loop and intracellular N- and C-termini5,6. Several consensus cysteine residues are in the extracellular loop and are essential and necessary for intercellular docking of gap junction hemichannels in the opposing cell membrane5-7.
Pannexins (Pannexin 1, Pannexin 2 and Pannexin 3) belong to the superfamily of gap junction proteins. Pannexin 1 (PANX1) is ubiquitously expressed, Pannexin 2 (PANX2) is specifically expressed in the human brain and widespread in rodents and Pannexin 3 (PANX3) is also detected in the brain8.
The gating properties of Pannexins were studied in Xenopus oocytes and results demonstrate that only PANX1 is able to form homomeric hemichannels, and is also able to form heteromeric hemichannels with PANX2 but not with PANX39,10. Not surprising, PANX1 gating properties depend whether it forms homomeric or heteromeric hemichannels.
A number of different stimuli are known to open these channels and include mechanical stress, extracellular ATP, increases in intracellular Ca2+ and inflammation9.
Possible roles for Pannexins include paracrine signaling in vascular endothelial cells and taste cell signaling9. Pannexin-1 was shown to interact with NMDA receptors in epilepsy, ischemia, pain and other pathologies10.
Guinea Pig Anti-Pannexin 1 Antibody (#ACC-234-GP) is a highly specific antibody directed against an epitope of the human protein. The antibody can be used in western blot and immunohistochemistry applications. It has been designed to recognize Pannexin 1 from mouse, rat and human samples.
The antigen used to immunize guinea pigs is the same as Anti-Pannexin 1 Antibody (#ACC-234) raised in rabbit. Our line of guinea pig antibodies enables more flexibility with our products such as multiplex staining studies, immunoprecipitation and more.
Anti-Adenosine A1 Receptor (extracellular) Antibody (#AAR-009)
Anti-Connexin-26 (GJB2) Antibody (#ACC-212)
Anti-Connexin-36 Antibody (#ACC-209)
Anti-P2X7 Receptor Antibody (#APR-004)
Anti-P2Y1 Receptor (extracellular) Antibody (#APR-021)
Anti-Pannexin 1 Antibody (#ACC-234)
Anti-Pannexin 2 (extracellular) Antibody (#ACC-232)
Pannexin 1 Blocking Peptide (#BLP-CC234) is the original antigen used for immunization during Anti-Pannexin 1 Antibody (#ACC-234) generation. The blocking peptide binds and 'blocks' Anti-Pannexin 1 primary antibody, this makes it a good negative reagent control to help confirm antibody specificity in western blot and immunohistochemistry applications. This control is also often called a pre-adsorption control.
Blocking Peptide Protocols for Immunohistochemistry (IHC) and Immunocytochemistry (ICC)
Immunohistochemistry (IHC) Protocols for Frozen Sections: Indirect Methods
Sample Preparation Protocols for Tissues
Western Blot (WB) Protocol
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PLoS One. 2015 Dec 16;10(12):e0145153. doi: 10.1371/journal.pone.0145153. eCollection 2015.
Smooth Muscle-Like Cells Generated from Human Mesenchymal Stromal Cells Display Marker Gene Expression and Electrophysiological Competence Comparable to Bladder Smooth Muscle Cells.
Brun J1, Lutz KA1, Neumayer KM1, Klein G2, Seeger T2, Uynuk-Ool T3, Wörgötter K3, Schmid S4, Kraushaar U4, Guenther E4, Rolauffs B3, Aicher WK1, Hart ML1,3.
Clinical Research Group KFO 273, Department of Urology, University of Tübingen, Tübingen, Germany.
Center for Medical Research, University Medical Clinic, Department II, University of Tübingen, Tübingen, Germany.
Siegfried Weller Institute for Trauma Research, Laboratory for Molecular Biomechanics, University of Tübingen, Tübingen, Germany.
NMI Natural and Medical Sciences Institute at the University of Tübingen, Department of Electrophysiology, Reutlingen, Germany.
The use of mesenchymal stromal cells (MSCs) differentiated toward a smooth muscle cell (SMC) phenotype may provide an alternative for investigators interested in regenerating urinary tract organs such as the bladder where autologous smooth muscle cells cannot be used or are unavailable. In this study we measured the effects of good manufacturing practice (GMP)-compliant expansion followed by myogenic differentiation of human MSCs on the expression of a range of contractile (from early to late) myogenic markers in relation to the electrophysiological parameters to assess the functional role of the differentiated MSCs and found that differentiation of MSCs associated with electrophysiological competence comparable to bladder SMCs. Within 1-2 weeks of myogenic differentiation, differentiating MSCs significantly expressed alpha smooth muscle actin (αSMA; ACTA2), transgelin (TAGLN), calponin (CNN1), and smooth muscle myosin heavy chain (SM-MHC; MYH11) according to qRT-PCR and/or immunofluorescence and Western blot. Voltage-gated Na+ current levels also increased within the same time period following myogenic differentiation. In contrast to undifferentiated MSCs, differentiated MSCs and bladder SMCs exhibited elevated cytosolic Ca2+ transients in response to K+-induced depolarization and contracted in response to K+ indicating functional maturation of differentiated MSCs. Depolarization was suppressed by Cd2+, an inhibitor of voltage-gated Ca2+-channels. The expression of Na+-channels was pharmacologically identified as the Nav1.4 subtype, while the K+ and Ca2+ ion channels were identified by gene expression of KCNMA1, CACNA1C and CACNA1H which encode for the large conductance Ca2+-activated K+ channel BKCa channels, Cav1.2 L-type Ca2+ channels and Cav3.2 T-type Ca2+ channels, respectively. This protocol may be used to differentiate adult MSCs into smooth muscle-like cells with an intermediate-to-late SMC contractile phenotype exhibiting voltage-gated ion channel activity comparable to bladder SMCs which may be important for urological regenerative medicine applications.
Expression levels of contractile SMC-specific genes.
MSCs were expanded in GMP expansion medium until they were 70% confluent and at passage 2 treated with control medium (CM) or SMC differentiation medium (5 ng/mL human TGF-β1, 5 ng/mL human PDGF-AB and 30 μM ascorbic acid) for 0, 3, 7, 14, 21 and 28 days. Differentiation was analyzed by qRT-PCR. Transcript levels were calculated relative to GAPDH and PPIA. (A) Data was calculated relative to CM for that time point. * p<0.05 compared to CM at the respective day of differentiation. (B) Data was calculated relative to day 0, the starting point of differentiation. * p<0.05 compared to CM at the respective day of differentiation; † p<0.05 compared to day 0. n = 6–8. Error bars indicate SEM.
Expression of contractile SMC-specific proteins analyzed by immunofluorescence.
MSCs were expanded in GMP expansion medium until they were 70% confluent and at passage 2 treated with control medium or SMC differentiation medium for 14 days, fixed and then analyzed by immunofluorescence for expression of αSMA, transgelin, calponin and SM-MHC. Primary human bladder smooth muscle cells (HBdSMC) served as the positive control. Nuclei were stained with DAPI. Magnification 20x. Representative of n = 3.
Expression of contractile SMC-specific proteins analyzed by Western blot.
MSCs from three donors were treated with control medium (CM) or SMC differentiation medium (DM) for 0 or 14 days and the expression pattern of αSMA, transgelin and calponin was compared to the positive control (control 1: bladder tissue) and the negative control (control 2: PBMCs) by Western blot. Representative of n = 3.
Expression levels of αSMA ex vivo, after MSCs expansion and myogenic differentiation in vitro.
(A) Mononuclear cells were directly isolated from bone marrow ex vivo and assessed for expression of αSMA by flow cytometry. Viable cells were gated (SSC/FSC), CD45+ cells were excluded, and expression of αSMA was recorded in the cytoplasm of the CD45-CD271+ fraction of the mononuclear cells. The histogram represents αSMA in the cytoplasm of CD271+ cells (solid line) compared to the unstained controls (dotted line). (B) MSCs were expanded in GMP-compliant expansion medium and then assessed for expression of αSMA in the cytoplasm of the cells. Viable cells were gated (SSC/FSC) and αSMA+ cells were recorded (solid line). The dotted histogram represents the unstained controls. The broad profile of the histogram indicates that a large portion of MSCs express αSMA after expansion and prior to induction of differentiation (27% of MSCs were positive, MFI of 38). (C) After expansion in GMP-compliant expansion medium MSCs were differentiated for 14 days. Then expression of αSMA in the cytoplasm of differentiating MSCs was explored (solid line). The histogram indicates that more cells contain αSMA after differentiation (27% of MSCs were positive, MFI of 42, right panel). The dotted lines represent unstained controls.
Determination of osteogenic and adipogenic differentiation.
MSCs were cultured in control medium, SMC differentiation medium, osteogenic differentiation medium or adipogenic differentiation medium as indicated for 14 days. HbdSMCs were cultured in SMC medium (smooth muscle cell growth medium 2). Osteogenic differentiation was assessed by Von Kossa staining (A-D) and adipogenic differentiation by Oil Red O staining (E-H). Magnification 20x. Representative of n = 3.
Levels of voltage-activated Na+ currents and Na+ channels.
(A) Voltage-activated Na+ currents were elicited by a voltage step from -120 mV to +20 mV. MSCs: trace from undifferentiated MSCs in control medium (undiff MSC-FBS) and GMP expansion medium (MSC-GMP); d7: trace from MSCs after 7 days in myogenic differentiation medium; SMC: trace from primary bladder SMCs. Capacitive transient is blanked for better visualization. (B) Na+ current density for undifferentiated MSCs in control medium (MSC FBS) and GMP medium (MSC GMP), as well as MSCs differentiated for 7, 14 or 21 days and SMCs, respectively. n = 10–20. * p<0.05. Error bars indicate SEM. (C) Effect of TTX on Na+ currents in undifferentiated MSCs (here: MSC in control medium). Superposition of Na+ currents elicited at +20mV. Na+ channels could be blocked by the specific Na+ channel inhibitor TTX. (D) Effect of TTX on Na+ currents in MSCs that were differentiated for 7 days. Superposition of Na+ currents elicited at +20mV. TTX blocks the current concentration-dependently.
Blockage of voltage-gated Na+ channel subtypes.
(A) Application of 100nM ranolazine reduced the peak amplitude of voltage-activated Na+ channels [(n = 3 for undifferentiated MSCs (cultured in GMP expansion medium), n = 4 for SMCs, n = 5 for MSCs that were differentiated for 5–10 days and n = 7 for MSCs differentiated for 13–21 days (Diff MSC)] compared to the respective control (= 1.0, not shown). (B) Application of pro-toxin II inhibited voltage-gated Na+ channels in SMCs. Superposition of single current traces obtained in control (bold), at 2nM (dashed) and 100nM (dotted) from one donor, respectively. (C) Summary plot of current inhibition by pro-toxin II. Data obtained from n = 4 experiments. * p<0.05. Error bars indicate SEM.
Ca2+ imaging of (A) bladder SMCs and (B) differentiated MSCs (d7). K+-induced depolarization increased the intracellular Ca2+ content (black trace). Depolarization in the presence of 50 μM Cd2+ prevented the Ca2+ increase (dashed trace). (C) In undifferentiated MSCs (expanded in GMP expansion medium) no transient increase in cytosolic Ca2+ was observed in response to K+ induced depolarization. Arrow indicates time point in which 15 mM K+ was added to the bath solution.
Expression levels of potassium and L- and T-type calcium ion channels.
(A) Bladder SMCs were compared to (B) MSCs treated with SMC differentiation medium for 7 days for expression of ion channels. Transcript levels of KCNMA1 (potassium ion channel), CACNA1C (Cav1.2 L-type Ca2+ channel) and CACNA1H (Cav3.2 T-type Ca2+ channel) were measured by qRT-PCR and expressed as target/reference ratio relative to GAPDH and PPIA. n = 3. Error bars indicate SEM.
Contraction of differentiated MSCs and bladder SMCs.
Contraction was measured by quantifying changes in cellular length. MSCs of three different donors were cultured in control medium or differentiation medium for 7 days and compared to bladder SMCs. To illustrate the process of determining cellular length, representative images of Calcein-stained MSCs in control medium 10 seconds and 3 minutes after KPSS addition are shown in (A). The red lines are reference lines for assessing cellular dimensions at each time point. The green line indicates a change in the cell length. The images generated through manual thresholding are illustrated in (B). Note that the threshold dimensions (highlighted in white) correspond exactly with the original cellular dimensions in (A). (C) Automated image processing for measuring cellular length resulted in images highlighting cellular outlines, upon which the measurement of cellular length was based. Representative images of 70 MSCs in control medium, of 58 MSCs that were differentiated for 7 days and of 62 bladder SMCs as shown in A, D and E, respectively. A decrease in cellular length was emphasized with red and green lines depicting cellular dimensional changes (D and E). Quantification of these changes in cellular length are depicted in (F) and expressed as change in cellular length (% of initial). Error bars indicate SEM. * p<0.05 comparing cell length at 10 seconds vs. 3 minutes after KPSS addition show that both differentiated MSCs and SMCs, but not MSCs in control medium, exhibited a significant decrease in cellular length. † p<0.05 compared to control medium and bladder SMCs show that MSCs in differentiation medium exhibited a significantly larger change in cellular length, compared to MSCs in control medium and to SMCs.
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Cerebellar Purkinje cells control eye movements with a rapid rate code that is invariant to spike irregularity
Hannah L Payne,
Ranran L French,
Christine C Guo,
TD Barbara Nguyen-Vu,
Tiina Manninen,
Jennifer L Raymond ,
Stanford University, United States;
University of Rochester, United States;
QIMR Berghofer Medical Research Institute, Australia;
Tampere University, Finland;
Research Article May 3, 2019
Cited 0
The rate and temporal pattern of neural spiking each have the potential to influence computation. In the cerebellum, it has been hypothesized that the irregularity of interspike intervals in Purkinje cells affects their ability to transmit information to downstream neurons. Accordingly, during oculomotor behavior in mice and rhesus monkeys, mean irregularity of Purkinje cell spiking varied with mean eye velocity. However, moment-to-moment variations revealed a tight correlation between eye velocity and spike rate, with no additional information conveyed by spike irregularity. Moreover, when spike rate and irregularity were independently controlled using optogenetic stimulation, the eye movements elicited were well-described by a linear population rate code with 3–5 ms temporal precision. Biophysical and random-walk models identified biologically realistic parameter ranges that determine whether spike irregularity influences responses downstream. The results demonstrate cerebellar control of movements through a remarkably rapid rate code, with no evidence for an additional contribution of spike irregularity.
Action potentials, or spikes, are the primary language used by the nervous system. Throughout the brain, the rate at which neurons fire spikes encodes information (Adrian, 1928; Kuffler, 1951; Hubel and Wiesel, 1959; Wright et al., 1967; reviewed in Borst and Theunissen, 1999), affects the activity of downstream neurons (Tsodyks and Markram, 1997; Bagnall et al., 2008; Turecek et al., 2016), and drives motor output (Crowell et al., 1968; Evarts, 1968; Evarts, 1969; Henn and Cohen, 1976; Georgopoulos et al., 1982; Hanes and Schall, 1996; reviewed in Ebbesen and Brecht, 2017), indicating that a rate code is widely used for neural computation. In addition, the precise temporal pattern of spikes can encode information beyond that carried by spike rate, suggesting that a temporal code may also contribute to information processing (O'Keefe and Recce, 1993; Theunissen and Miller, 1995; Gawne et al., 1996; de Ruyter van Steveninck et al., 1997; Stopfer et al., 1997; Victor, 1999; Stopfer and Laurent, 1999; Reich et al., 2000; Panzeri et al., 2001; Huxter et al., 2003; Butts et al., 2007; Engineer et al., 2008; Gollisch and Meister, 2008; Huxter et al., 2008). However, it is not clear whether and how information encoded in the temporal pattern of spikes is transmitted to downstream circuits to influence behavior. Here we leveraged the experimental advantages of the oculomotor system to analyze whether the temporal pattern of spikes in cerebellar neurons contributes to their control of behavioral output.
Temporal coding can take many forms, which fall into two categories: coding based on the precise timing of spikes within the spike train of an individual neuron, or coding based on the precise timing of spikes in one neuron relative to spikes in other neurons. In the cerebellum, previous work has analyzed both types of spike timing in Purkinje cells, which are the sole output neurons of the cerebellar cortex (Person and Raman, 2012a; Steuber and Jaeger, 2013; Sarnaik and Raman, 2018; reviewed in De Zeeuw et al., 2011; Person and Raman, 2012b). Here, we investigated the impact of the temporal pattern of spikes within individual Purkinje cells.
It has been hypothesized that the irregularity of Purkinje cell spiking affects the cerebellar control of movements (reviewed in De Zeeuw et al., 2011). The irregularity of the interspike intervals (ISIs) is a temporal feature of spike trains that varies along a continuum across brain regions and across individual neurons (Maimon and Assad, 2009), from highly regular or clock-like (Guinan et al., 1972) to highly irregular or supra-Poisson (Fernandez and Goldberg, 1971). Further, in a given neuron, the level of spike irregularity can vary as the neuron processes information (Barlow and Levick, 1969; Young et al., 1988; de Ruyter van Steveninck et al., 1997; Fairhall et al., 2001). In Purkinje cells, spontaneous spiking is more regular than a Poisson process (Häusser and Clark, 1997; Shin et al., 2007), and spike irregularity can vary during the processing of sensory signals (Shin et al., 2007). Moreover, pathological alteration of the spike irregularity of Purkinje cells has been proposed as a potential cause of ataxia and other cerebellum-related disorders such as autism. In several different mouse models of ataxia (Hoebeek et al., 2005; Walter et al., 2006; Alviña and Khodakhah, 2010b; Alviña and Khodakhah, 2010a; Stahl and Thumser, 2014; Mark et al., 2015; Jayabal et al., 2016) and autism (Peter et al., 2016), Purkinje cell spiking is more irregular than in normal Purkinje cells. Moreover, increases in the regularity of Purkinje cell spiking, caused by reductions in inhibitory synaptic input (Wulff et al., 2009) or maternal exposure to cannabinoids (Shabani et al., 2011), have also been associated with motor deficits. Such observations of increased or decreased spike irregularity in Purkinje cells in mouse models of ataxia have inspired the hypothesis that any perturbation of normal spike irregularity may impair the ability of Purkinje cells to reliably transmit information for the control of movement (Hoebeek et al., 2005; Walter et al., 2006; Wulff et al., 2009; Alviña and Khodakhah, 2010b; Alviña and Khodakhah, 2010a; Luthman et al., 2011; De Zeeuw et al., 2011). Computer modeling has identified short-term synaptic depression as one potential mechanism that would allow spike irregularity in Purkinje cells to influence their control of postsynaptic targets. Because irregular presynaptic spike trains contain short ISIs that recruit more short-term depression, short-term depression has the potential to reduce the mean synaptic conductance in the postsynaptic target during more irregular spike trains (Luthman et al., 2011). However, causal evidence for a direct contribution of irregularity to impaired motor control is mixed. In mouse models of ataxia, treatments that reverse the abnormally high irregularity have reversed motor deficits in some cases (Alviña and Khodakhah, 2010b; Alviña and Khodakhah, 2010a; Walter et al., 2006; Jayabal et al., 2016), but not others (Stahl and Thumser, 2013). Moreover, the severity of motor deficits in different mouse lines does not always correspond to the severity of the perturbation of Purkinje cell spike irregularity in the relevant region of the cerebellum (Stahl and Thumser, 2014).
Studies of pathological alterations in Purkinje cell irregularity in mouse models of ataxia raised the question of whether natural variations in the level of Purkinje cell spike irregularity during normal behavior might impact motor output, in addition to the influence of spike rate. To analyze whether spike irregularity is a component of the neural code used by Purkinje cells to control behavior, we took advantage of the close link between the activity of Purkinje cells in the cerebellar flocculus and motor output. Located just two synapses from the motor neurons that innervate the eye muscles, floccular Purkinje cells are a key node in the sensorimotor transformation of visual and vestibular signals into oculomotor commands. Recording and stimulation studies in a range of species have established an influence of Purkinje cell spike rate on eye movement behavior (Lisberger and Fuchs, 1978; Noda and Suzuki, 1979; Stone and Lisberger, 1990; Lisberger et al., 1994; Lisberger, 1994; Kahlon and Lisberger, 1999; Nguyen-Vu et al., 2013; Katoh et al., 2015; Kodama and du Lac, 2016). The possibility that the spike irregularity of floccular Purkinje cells might also influence eye movements has been suggested by the observation of abnormal oculomotor behavior or oculomotor learning in mouse models of ataxia with abnormal Purkinje cell spike irregularity (Hoebeek et al., 2005; Katoh et al., 2007; Katoh et al., 2008; Wulff et al., 2009; Stahl and Thumser, 2014). Here, we used a combination of recording, stimulation, and computational approaches to assess whether and how spike irregularity contributes to the control of eye movements by the cerebellum.
Mean spike rate and irregularity both vary with oculomotor behavior
We analyzed spike trains from Purkinje cells recorded in the cerebellar flocculus and ventral paraflocculus of rhesus monkeys and the flocculus of mice while they made smooth eye movements in response to a variety of vestibular and visual stimuli (for full descriptions of the stimuli, see Materials and methods). It is well established that the spike rate of a majority of Purkinje cells in this region of the cerebellum encode gaze velocity (Lisberger and Fuchs, 1974; Lisberger et al., 1994; Pastor et al., 1997; Raymond and Lisberger, 1998; Hirata and Highstein, 2000; Katoh et al., 2015). We assessed whether spike irregularity in these neurons also correlates with gaze velocity, and hence might contribute to the control of gaze.
Consistent with previous work (Lisberger and Fuchs, 1978; Lisberger et al., 1994; Pastor et al., 1997; Raymond and Lisberger, 1998; Hirata and Highstein, 2001; Katoh et al., 2015), the spike rate of Purkinje cells in our samples was highly correlated with gaze velocity. Gaze velocity is defined as the angular velocity of the eye in world coordinates, which is equal to the sum of eye velocity in the head, plus head velocity in the world. When animals tracked a moving visual stimulus with the head stationary, gaze velocity was equal to eye velocity, and there was a clear correlation between Purkinje cell spike rate and gaze velocity, in both the population mean (Figure 1A left) and individual cells (Figure 1B), in both monkeys (Figure 1C top) and mice (Figure 1C bottom, Figure 1—figure supplement 1). Similarly, when monkeys or mice held their eyes roughly stationary relative to the head to track a visual stimulus that moved with the head, a behavior known as cancellation of the vestibulo-ocular reflex, gaze velocity closely tracked head velocity, and spike rate was again correlated with gaze velocity (Figure 1A right, Figure 1C, Figure 1—figure supplement 1). The same, roughly linear relationship between spike rate and gaze velocity was observed during eye movement responses to multiple combinations of visual and vestibular stimuli with different velocity profiles, and when the visual stimulus used to drive eye movements was a large-field visual stimulus (monkeys and mice) or a small visual target (monkeys only) (Figure 1C; mean correlation coefficient across conditions 0.81 ± 0.02, p=10−69, n = 120 cells, monkey; correlation coefficient 0.71 ± 0.04, p=10−19, n = 33 cells, mouse).
Spike rate and irregularity during oculomotor behavior.
(A) Visual and vestibular stimuli, oculomotor responses, and Purkinje cell spike rate and local spike irregularity (CV2) during two oculomotor behaviors in rhesus monkeys: visual tracking (smooth pursuit of a small visual target; left) and VOR cancellation (cancellation of the vestibulo-ocular reflex, achieved by tracking a visual target that moves exactly with the head; right). Upward deflections represent ipsiversive movements of the visual stimulus, head, eye, or gaze; downward deflections represent contraversive movements (relative to the side of the brain in which the Purkinje cell was recorded). Data were averaged across stimulus cycles (median 24 cycles, range 10 to 118) for each neuron, and then averaged across neurons (n = 66 cells from two monkeys, data reanalyzed from Raymond and Lisberger, 1998). For clarity of illustration, the average cycle is repeated twice. Results are shown for the largest subclass of Purkinje cells in the cerebellar flocculus, the EiHi Purkinje cells, which increase their firing in response to ipsiversive eye motion during visual tracking and ipsiversive head motion during VOR cancellation (Raymond and Lisberger, 1997). Results from Purkinje cells with other responses to eye or head motion are shown in Figure 1—figure supplement 2. (B) The relationship between spike rate and gaze velocity (top) and spike irregularity (CV2) and gaze velocity (bottom) during visual tracking for individual Purkinje cells included in the averages in panel (A). Spike rate, CV2, and gaze velocity were first averaged across stimulus cycles, and then binned according to gaze velocity (2°/s bins). The average spike rate or CV2 was subtracted from each cell to obtain Δ spike rate or Δ CV2, respectively. (C) The relationship between spike rate and gaze velocity during eye movement responses to different combinations of vestibular and visual stimuli (see Materials and methods for descriptions of each visual-vestibular stimulus listed in the legend). The Δ spike rate and Δ irregularity were calculated as in (B) and then averaged across the population of all EiHi Purkinje cells recorded in monkeys (top; n = 120 cells from four monkeys, data reanalyzed from Raymond and Lisberger, 1998; Raymond and Lisberger, 1997; Kimpo et al., 2014) and mice (bottom; n = 33 cells from 29 mice, data reanalyzed from Katoh et al., 2015). (D) The relationship between spike irregularity (CV2) and gaze velocity averaged across the population of Purkinje cells recorded in monkeys (top) and mice (bottom). (E) The relationship between spike rate and spike irregularity (CV2), averaged across the population of Purkinje cells recorded in monkeys (top) and mice (bottom) and plotted for each 2 ms time point within the stimulus cycle. Spontaneous activity is plotted in gray. In this and all figures, error bars represent ± SEM.
Like spike rate, spike irregularity was also correlated with gaze velocity across a range of visual and vestibular stimulus conditions in both monkeys and mice (Figure 1A,B,D). Spike irregularity was quantified using the coefficient of variation-2 (CV2) of the ISIs, which provides a local measure of the variation in ISIs. In contrast to the coefficient of variation (CV) of the ISIs, the CV2 is not strongly influenced by smooth changes in spike rate. Therefore, CV2 provides a useful measure of irregularity when there are underlying changes in rate (Holt et al., 1996; Shin et al., 2007; Wulff et al., 2009; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015; Jayabal et al., 2016; Peter et al., 2016). The CV2 is calculated by taking the absolute difference between each adjacent pair of ISIs, divided by their mean:
(1) CV2i=|ISIi+1−ISIi|(ISIi+1+ISIi)/2
where ISIi =ti-ti-1, and ti represents the time of spike i. The CV2 can range from 0 (two identical ISIs) to a theoretical maximum of 2 (one small ISI adjacent to one infinitely long ISI), with the mean CV2 of a Poisson process equal to 1 (Holt et al., 1996), and higher values of CV2 reflecting more irregular spiking. The CV2 was calculated for each pair of ISIs and interpolated to yield an instantaneous estimate of spike irregularity (see Materials and methods), thus characterizing the irregularity of Purkinje cell spiking on a timescale similar to that for estimating instantaneous spike rate. During visual tracking and VOR cancellation, there was modulation of spike irregularity that mirrored the modulation of gaze velocity, with CV2 increasing for gaze movements in one direction and decreasing for gaze movements in the other direction (Figure 1A, purple). More generally, across the set of visual and vestibular stimulus conditions tested, a roughly linear relationship between spike irregularity and gaze velocity was observed in individual Purkinje cells (Figure 1B, bottom; Figure 1—figure supplement 1) and in the population means (Figure 1D) recorded in monkeys and mice (mean correlation coefficient across conditions –0.53 ± 0.03, p = 10−38, n = 120 cells, monkey; –0.47 ± 0.05, p = 10−10, n = 33 cells, mouse).
The observation that the mean spike irregularity of floccular Purkinje cells, like the mean spike rate, was correlated with oculomotor behavior raised the possibility that both features of the spike train might contribute to the control of eye movement behavior in wild type mice. However, the respective contributions of spike rate and irregularity could not be dissociated based on the responses quantified by averaging across trials, since mean spike rate and mean irregularity covaried. Whenever mean spike rate was high, mean CV2 was lower (spike timing was more regular), and when mean spike rate was low, mean CV2 was high (spike timing was more irregular) (Figure 1E). The inverse relationship between spike rate and CV2 was observed in the Purkinje cells that encode ipsiversive gaze velocity, which make up the largest subset of Purkinje cells in the cerebellar flocculus (plotted in Figure 1), and also in Purkinje cells with different responses to eye velocity or vestibular input (Figure 1—figure supplement 2). This covariation between spike rate and irregularity may reflect, in part, a tendency for the refractory period to cause spiking to be more regular at high rates (Holt et al., 1996); however, simulations of Poisson spiking with an imposed refractory period did not fully capture the correlation between spike rate and irregularity (Figure 1—figure supplement 3; see Holt et al., 1996), and several additional factors are thought to influence spike irregularity in Purkinje cells, including voltage-gated conductances (Raman and Bean, 1997; Raman and Bean, 1999; Hoebeek et al., 2005; Alviña and Khodakhah, 2010b; Alviña and Khodakhah, 2010a; Gao et al., 2012; Stahl and Thumser, 2014) and synaptic input (Häusser and Clark, 1997; Jaeger and Bower, 1999; Shin et al., 2007; Wulff et al., 2009; Jelitai et al., 2016; Peter et al., 2016). Indeed, over short timescales within individual trials, spike rate and CV2 did not covary strongly (Figure 2—figure supplement 1), and we leveraged this dissociation to assess the contribution of each of these features of the spike trains to the control of eye movements.
Spike rate, but not irregularity, predicts moment-to-moment variations in eye velocity
Moment-to-moment variations in neural activity and behavior allowed the contribution of spike irregularity to be distinguished from that of spike rate (Figure 2, Figure 2—figure supplement 1). For each Purkinje cell, residual spike rate, residual CV2, and residual eye velocity were calculated by subtracting the corresponding trial mean from the response on each individual trial, computed in 50 ms time bins (Figure 2A,B). The ability of spike rate and spike irregularity (CV2) to predict eye velocity were then statistically compared using a linear mixed effects model (see Materials and methods). This analysis found a significant contribution of residual spike rate, but not residual CV2, for predicting residual eye velocity in monkeys (rate: p=0.006; CV2: p=0.56; interaction: p=0.17; likelihood ratio test) and mice (rate: p=0.035; CV2: p=0.38; interaction: p=0.46) (Supplementary file 1; see Materials and methods). Spike rate was therefore a better predictor of moment-to-moment eye velocity than spike irregularity.
Residual analysis of spike rate and irregularity during oculomotor behavior.
(A) Example traces of raw eye velocity, instantaneous spike rate, and spike irregularity (thick lines) during two cycles of sinusoidal visual tracking in monkey, calculated in 50 ms bins, and overlaid on the mean responses across all cycles for this Purkinje cell (thin black lines). (B) Residuals were calculated by subtracting the mean response from the raw response. For visualization only (panels C–F) the residual spike rates and CV2 values were divided into the lower and upper thirds of the distribution for each cell (shading). Statistical analysis was conducted on the full distribution of residuals (see text). (C,D) The relationship between residual spike rate and residual eye velocity, plotted separately for time bins with residual CV2 values in the lower (blue) or upper (red) third of the CV2 distribution for each cell, and then averaged across Purkinje cells for monkeys (C, n = 120 cells from four monkeys) and mice (D, n = 33 cells from 29 mice). (E,F) The relationship between residual spike irregularity (CV2) and residual eye velocity, plotted separately for time bins with residual spike rate values in either the lower (light gray) or upper (dark gray) third of the spike rate distribution for each cell, for monkeys (E) and mice (F).
To visualize this result, the relationship between residual eye velocity and residual spike rate was plotted separately for time bins in which the CV2 fell into the lower or upper third of the CV2 distribution for each cell (Figure 2B bottom, red vs. blue shading; Figure 2C,D, red vs. blue traces). There was a consistent correlation between residual spike rate and residual eye velocity (Figure 2C,D): on trials with higher than average spike rate at a particular time within the trial, eye velocity was also higher than average at that time within that trial. One extra spike in a 50 ms time bin, corresponding to a 20 sp/s fluctuation in spike rate, was associated with a roughly 0.1°/s change in eye velocity, consistent with the correlation between single spikes and visual tracking behavior reported by Chaisanguanthum et al. (2014). The same relationship between residual spike rate and eye velocity was observed for time bins with high or low CV2 (Figure 2C,D), consistent with the conclusion of the linear mixed effects model that spike irregularity did not substantially modulate the effects of spike rate on eye movements (no main effect of CV2 or interaction between spike rate and CV2, Supplementary file 1). Moreover, when residual eye velocity was plotted against residual CV2, there was no correlation (Figure 2E,F). Therefore, although on average, both spike rate and irregularity were correlated with each other and with motor output during eye movement behaviors (Figure 1), moment-to-moment variations in eye velocity could be explained by moment-to-moment variations in spike rate, but not spike irregularity. Thus, the recording results found no evidence that spike irregularity influenced motor output during oculomotor behavior.
Optogenetically-driven Purkinje cell spike rate controls motor output independent of spike irregularity
Stimulation experiments provided a causal test of the relationship between spike irregularity and oculomotor behavior. Optogenetic stimulation of Purkinje cells made it possible to independently manipulate spike rate and irregularity by delivering sequences of light pulses with different stimulus rates and irregularities. Channelrhodopsin-2 (ChR2) was selectively expressed in Purkinje cells by crossing a conditional ChR2 mouse line (Madisen et al., 2012) with the L7/Pcp2-Cre Jdhu line, which is highly selective for Purkinje cells (Zhang et al., 2004; Witter et al., 2016). Purkinje cells expressing ChR2 were stimulated in vivo using 500 ms trains of 1 ms pulses of light delivered at mean rates from 20 Hz to 100 Hz. For a given mean rate, the exact same number of pulses were delivered during each train, with variations only in the irregularity of the stimulus pulse timing, so that the CV of each stimulus train was either 0 (perfectly regular), 0.5 (intermediate irregular), or 1 (approximately Poisson irregular) (see Materials and methods). In these experiments, the more common CV measure was used to characterize the irregularity of the stimulus trains rather than CV2, since there was no additional variation in rate. For the irregular stimulus trains, 60 different patterns were randomly generated for each frequency ('non-repeated'). In addition to the non-repeated trains, for a subset of stimulus frequencies (20 Hz, 60 Hz, and 100 Hz) one representative irregular (CV = 1) stimulus pattern was repeated ('repeated') to provide a measure of trial-to-trial variability, and to allow visualization of the average response to an irregular train. Because Purkinje cells have high rates of spontaneous spiking, the actual spike irregularity and rate achieved in Purkinje cells differed from that of the stimulus trains, and thus was measured explicitly (see below). Stimulus trains were delivered unilaterally to the flocculus of awake, head-restrained mice in a completely dark room, and the resulting eye movements were measured.
Extracellular recordings confirmed that optogenetic stimulation effectively dissociated spike rate and irregularity in Purkinje cells in vivo. Purkinje cells in the flocculus were identified based on their reliable, short-latency responses to 1 ms light pulses (median first-spike latency 1.24 ± 0.07 ms, standard deviation 1.36 ± 0.17 ms, n = 13, 1 mW light intensity; Figure 3A–C), and their identity was confirmed by their characteristic spike waveform (Figure 3A), high-frequency spontaneous activity (62.2 ± 6.9 sp/s, n = 13), and recording location within the layers of the cerebellar cortex. Putative interneurons were also recorded, which did not have short-latency responses to light pulses (Figure 3B,C), and which had different spike waveforms, spontaneous rates, and/or recording locations than the Purkinje cells. Since the interneurons can influence behavior only via their effects on the output of Purkinje cells, interpretation of the relationship between Purkinje cell spiking and motor output is not affected by the activity of the interneurons, hence they were not analyzed further.
Optogenetic stimulation of Purkinje cells with regular and irregular stimulus trains.
(A) Recordings of optogenetically-driven spikes in an example Purkinje cell. Left, first two principle components of waveforms sorted as noise (gray) or spikes (black). Middle, spontaneous and optogenetic stimulus-driven spike waveforms. Right, distribution of the latency to the first spike following a single light pulse (1 ms, 1 mW). (B) Histogram of median first-spike latencies following a single light pulse for the population of identified Purkinje cells and for other cerebellar cell types (1 ms, 1 mW light pulses). (C) Histogram of the percent of trials for which the first spike following the first light stimulus occurred within 5 ms, for Purkinje cells and other cell types. (D) Raster of spike times in the example Purkinje cell shown in (A) during 100 Hz trains of regular (CV = 0; left) and irregular (CV = 1, repeated; right) optogenetic stimulation. Colored triangles above rasters indicate the time of each 1 ms light pulse. Each row represents a single trial, with 31 trials shown for each stimulus train, spanning 60 min of recording. (E) Peristimulus time histograms (left; 5 ms bin width) and ISI distributions (right; 1 ms bin width) for the example cell during 20 Hz, 60 Hz, and 100 Hz regular and irregular optogenetic stimulation. (F) Mean spike rate (left) and CV (right) for the example cell as a function of stimulus rate. The black dashed line represents a 1:1 relationship between stimulus rate and the increase in Purkinje cell spike rate relative to the spontaneous baseline. Solid lines show the responses to the regular and irregular (non-repeated) stimuli. The red dashed line shows the response to the irregular (CV = 1, repeated) trains shown in (D,E). (G) Mean increase in spike rate relative to baseline (left) and mean CV (right) for the population of Purkinje cells (n = 12, 1 mW light intensity). There was a small but significant effect of stimulus irregularity on Purkinje cell spike rate (main effect of stimulus irregularity F(2,22) = 20.73, p=0.0009; interaction between rate and irregularity, F(10, 110)=5.48, p<0.0001, two-way repeated measures ANOVA; or F(2,24) = 4.89, p=0.017; F(10, 120)=4.87, p<0.0001 with inclusion of one additional outlier (not shown, see Materials and methods)). Importantly, there was a significant effect of stimulus irregularity on Purkinje cell spike irregularity (main effect of stimulus irregularity F(2,22) = 20.73, p<0.0001; interaction between rate and irregularity, F(10, 110)=15.07, p<0.0001, two-way repeated measures ANOVA; or F(2,24) = 21.0, p<0.0001; F(10, 120)=13.6, p<0.0001 with outlier included).
Purkinje cells responded to individual light pulses within each stimulus train (Figure 3D,E). The increase in spike rate above baseline, averaged over the 500 ms stimulus period, followed the stimulus rate in a roughly 1:1 manner, even for stimulus rates as high as 100 Hz (Figure 3F,G, left). Irregular stimulus trains drove slightly lower mean spike rates than regular trains (Figure 3G, left); this is taken into account in the analysis of the behavioral results below. Importantly, the overall irregularity of the combined spontaneous and optogenetically-driven Purkinje cell spikes consistently reflected the irregularity of the stimulus train (Figure 3F,G, right), with substantially more irregular spiking during the irregular stimulus trains compared to the regular stimulus trains. Thus, optogenetic stimulation provided differential control of spike rate and spike irregularity in cerebellar Purkinje cells.
Optogenetic stimulation of the Purkinje cells elicited robust eye movement responses. Discrete eye movement responses could be observed in response to each light pulse, even at stimulus frequencies as high as 100 Hz (Figure 4A,B). The sequence of light pulses during a train led to a cumulative deviation of the eye from its initial position, with greater total deviations in eye position for higher stimulus rates, and correspondingly higher mean eye velocities. The net eye movement response was quantified and compared across stimulus conditions by calculating the mean eye velocity during the 500 ms stimulus train. Like Purkinje cell spike rate, mean eye velocity increased with stimulus rate (Figure 4C,D), consistent with the Purkinje cells controlling eye velocity with a rate code. A similar correlation between stimulus rate and mean eye velocity was observed during both regular and irregular stimulus trains. The mean eye velocity evoked by irregular trains was slightly smaller than that evoked by regular trains; however, the mean Purkinje cell spike rate was also slightly smaller during irregular trains (Figure 3G). When mean eye velocity was assessed as a function of the actual mean spike rate recorded in the Purkinje cells rather than the stimulation rate, there was no significant difference in the net efficacy of the regular and irregular spike trains to drive eye movements (Figure 4E). Similar results were obtained using regular and irregular stimulus trains at a higher light intensity (10 mW, Figure 4—figure supplement 1). Thus, our stimulation results do not support the prediction from previous studies that more irregular Purkinje cell spike trains should have less impact downstream than more regular spike trains (Luthman et al., 2011; Hoebeek et al., 2005).
Eye movements evoked by regular and irregular Purkinje cell stimulation.
(A) Eye position averaged across trials in one representative mouse, during optogenetic stimulation of Purkinje cells with regular (left) or irregular (CV = 1, repeated; right) stimulus trains at 20, 60, and 100 Hz. Colored triangles indicate stimulus times. (B) Eye velocity averaged across trials in the example mouse. (C) Mean eye velocity, averaged across the 500 ms period of stimulation and plotted as a function of the stimulus rate, for the example mouse. Solid lines represent the results for regular and non-repeated irregular trains; dashed line represents the results from the repeated irregular trains. (D) Mean eye velocity as a function of the optogenetic stimulation rate, averaged across experiments (n = 16 flocculi from 10 mice). Colors indicate the stimulus irregularity, as in (C). There was a small but significant interaction of stimulus irregularity and stimulus rate on the mean eye movement responses (fixed effect of irregularity: p=0.34, interaction: p=0.021, likelihood ratio test of linear mixed effects model). (E) Mean eye velocity as a function of the mean increase in spike rate recorded in the population of Purkinje cells. Colors indicate the stimulus irregularity, as in (C). There was no significant effect of Purkinje cell irregularity on the mean eye movement responses (fixed effect of irregularity: p=0.86, interaction: p=0.80, likelihood ratio test of linear mixed effects model; with the outlier Purkinje cell included in the mean Δ Purkinje cell rate, fixed effect of irregularity: p=0.50; interaction: p=0.88).
Rapid rate code for eye movements
The net impact of Purkinje cell stimulation, as quantified by averaging eye velocity across the 500 ms period of optogenetic stimulation, did not depend on the irregularity of Purkinje cell spiking. On a finer timescale, the eye movement trajectories clearly depended on the exact temporal pattern of stimulation, with eye movements tracking the occurrence of individual stimuli within the train (Figure 4A,B). However, additional analysis demonstrated that these moment-to-moment eye movement trajectories could be well accounted for as a rapid, linear response of the eye to changes in the Purkinje cell population spike rate.
The population spike rate was estimated by combining binned spike histograms across the population of recorded Purkinje cells, aligned on the optogenetic stimulus trains. Optogenetic stimulus pulses drove spikes with similar, precise latencies in all recorded Purkinje cells (Figure 3B,C), causing rapid fluctuations in the population spike rate during the optogenetic stimulus trains, which paralleled the rapid fluctuations in eye velocity. We quantified the ability of the population spike rate to predict oculomotor output over these short timescales.
We first determined the decoding time window over which the population rate is decoded ('read out') by the downstream oculomotor circuitry. The decoding window is analogous to the encoding window used to analyze rate coding and temporal coding in sensory systems (Theunissen and Miller, 1995). The decoding window was evaluated by calculating mutual information to determine the timescale over which the population spike rate contained information about movements. Mutual information quantified the amount of information (in bits per second) that the Purkinje cell population spike rate conveyed about eye velocity during optogenetic stimulation, as spike rate and eye velocity were smoothed over successively longer time windows (see Materials and methods). Since there is a delay between neural activity and motor output, mutual information was initially calculated for a range of delays, and the delay that yielded the highest mutual information on average, 6 ms, was used in all subsequent analyses. For both regular and irregular stimulus trains, mutual information was maximal when spike rate and eye velocity were smoothed over a temporal window of 3–5 ms (Figure 5A). Mutual information decreased when spike rate was smoothed using windows shorter than 3 ms, indicating that fluctuations in spike rate and eye velocity at the shortest timescales were not as strongly related. Mutual information also decreased when the data were smoothed using windows longer than 5 ms, indicating that there is information about eye velocity in the rapid fluctuations of Purkinje cell spike rate that is lost by smoothing over intervals longer than 5 ms. Thus, the Purkinje cell population transmits a rate code that is decoded by the oculomotor circuitry on a timescale of 3–5 ms. Importantly, for rapid timescales encompassing this optimal decoding window of 3–5 ms, the same amount of information about eye movements was transmitted by the Purkinje cell rate code during regular and irregular stimulation (Figure 5A). Spike irregularity therefore did not alter the magnitude of the influence of spike rate on eye movements.
Purkinje cells control eye velocity with a rapid rate code.
(A) Mutual information between Purkinje cell spike rate and eye velocity during regular and irregular (CV = 1, repeated) optogenetic stimulus trains, calculated with the Purkinje cell spike rate smoothed by taking a moving average over time windows of different lengths ('Temporal smoothing'). Purkinje cell spike rate carried the same amount of information about eye velocity during the regular and irregular stimulus trains for temporal smoothing windows from 1 ms through 8 ms (all p>0.1 for 1 ms – 8 ms, 13 ms, and 20 ms; for other window lengths p ranges from 0.0003 to 0.0361, post hoc test with Sidak correction; two-way repeated measures ANOVA with significant interaction between smoothing window length and irregularity (F (19, 285)=11, p<0.0001, n = 16 flocculi from 10 mice; or all p>0.1 for 1 ms – 8 ms, 13 ms, and 20 ms and other p ranging from 0.0002 to 0.0223 with outlier Purkinje cell included). (B) Linear filter describing the transformation of Purkinje cell rate into eye velocity, fit using data from irregular stimulation (CV = 1, non-repeated; n = 16 flocculi from 10 mice). (C) Actual eye velocity (black) and predicted eye velocity (colors) in an example mouse for test stimuli that were not used to fit the linear filter model: regular and irregular (CV = 1, repeated) stimulation at 20, 60, and 100 Hz. (D) Actual versus predicted eye velocity at each 1 ms time point during the regular and irregular test stimuli, for the example mouse in (C). (E) Root mean squared error (RMSE) between actual and predicted eye velocity for each experiment (5.57 ± 0.45°/s regular, 5.56 ± 0.41°/s irregular, n = 16, p=0.92, n.s.: not significant, paired t-test; or p=0.87 with outlier Purkinje cell included). RMSE for the example mouse in (C,D) is plotted with hollow circles.
Not only did the instantaneous spike rate carry the same amount of information about eye velocity irrespective of spike irregularity, but the transformation between population spike rate and eye velocity could be described by the same linear temporal filter. For each stimulation experiment, a single linear filter was fit using total least squares regression of the eye velocity responses to the non-repeated irregular (CV = 1) stimulus trains at all frequencies (20, 40, 60, 80, 100 Hz) against the Purkinje cell responses to the same set of stimuli (Figure 5B). The linear filter was then used to predict the eye velocity responses to both the regular and the repeated irregular (CV = 1) stimulus trains, which had not been used to fit the filter, by convolving the filter with the Purkinje cell population spike rate during each stimulus train (Figure 5C). The linear filter model closely predicted eye velocity (Figure 5C,D) with root mean squared error (RMSE) that did not differ significantly between the regular and irregular test stimulus trains (Figure 5E). Further, when the model was fit to data from the regular stimulation at all frequencies (20, 40, 60, 80, 100 Hz), the resulting linear filter was nearly identical to the filter fit to the irregular data only (Figure 5—figure supplement 1). Thus, the same linear filter model described the relationship between spike rate and motor output equally well, regardless of the underlying spike pattern.
The rapid readout of the Purkinje cell rate code could render the circuit sensitive to changes in spike irregularity that alter the precision of the population spike rate (Walter et al., 2006). In particular, highly irregular spiking in individual Purkinje cells may degrade the precision of the motor commands carried by the population rate, by increasing its moment-to-moment and trial-to-trial variability. A simple simulation illustrates how spike irregularity in individual neurons can affect the accuracy of the population rate (Figure 6). Interspike intervals for a population of 50 simulated Purkinje cells were drawn from Gamma distributions with a given mean rate and level of irregularity. The instantaneous population rate was then calculated in 5 ms temporal windows (population rate = total number of spikes across the population divided by the number of neurons and the window duration). Higher spike irregularity increased the moment-to-moment variation in the population rate from the specified rate, as demonstrated by a broadening of the distribution of instantaneous population rates (Figure 6A). This broadening was subtle for variations in spike irregularity in the normal range observed in our recording and stimulation experiments and in previous studies of Purkinje cells in wild type mice (Figure 6A, blue and red; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015), but was more pronounced for the higher levels of irregularity that have been reported in mouse models of ataxia (Figure 6A, purple; Hoebeek et al., 2005; Walter et al., 2006; Luthman et al., 2011; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015). This variability in the population spike rate could in turn lead to greater behavioral variability, because the behavior tracks rapid fluctuations in the commands carried by the Purkinje cell population rate (Figure 5A). The degraded precision of the population rate code is apparent in receiver operating characteristic (ROC) curves representing the discriminability of two motor commands corresponding to target Purkinje cell population spike rates of 60 sp/s and 100 sp/s. The area under the ROC curve decreased with higher spike irregularity in the individual Purkinje cells, indicating decreased ability to discriminate distinct motor commands conveyed by the population spike rate (Figure 6B). This provides a potential reconciliation of our current finding of a rapid rate code for motor control with previous reports in ataxic mice suggesting that abnormally high irregularity of Purkinje cell spike trains disrupts normal downstream signaling and motor output (Hoebeek et al., 2005; Walter et al., 2006; Wulff et al., 2009; Alviña and Khodakhah, 2010b; Alviña and Khodakhah, 2010a; Luthman et al., 2011). Pathological levels of spike irregularity may cause ataxia, not through a direct effect of the irregularity itself, but by degrading the accuracy of the rapid rate code carried by Purkinje cells.
Effect of spike irregularity on the variability of the population spike rate.
(A) The probability density of the population spike rate, computed in 5 ms bins, for a population of 50 simulated Purkinje cells, each firing asynchronously at a given mean rate with the level of irregularity indicated in the legend. The two lower levels of irregularity (CV = 0.55 and CV = 0.82) correspond to the mean CV measured in Purkinje cells during 100 Hz regular or irregular optogenetic stimulation (Figure 3G). The high level of irregularity (CV = 1.7) is near the high end of the range reported in mouse models of ataxia (Hoebeek et al., 2005; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015) and was used in the simulations of Luthman et al. (2011). (B) Receiver operator characteristic (ROC) curve (Fawcett, 2006) for the distributions in (A), with the true positive fraction (sensitivity) plotted as a function of the false positive fraction (1 – specificity). Chance performance (no discrimination) is represented by the dashed diagonal line; perfect discrimination is represented by a step function beginning at the origin. Increasing the CV from 0.55 to 0.82 has a minor effect on the ability to discriminate the two frequencies, whereas discrimination is more impaired for a pathological level of irregularity (CV = 1.7).
Biophysical model of Purkinje cell synaptic transmission
We used a conductance-based model of the synapses between Purkinje cells and their postsynaptic targets to analyze the cellular properties governing how the temporal properties of Purkinje cell spike trains influence spiking in their target neurons (Luthman et al., 2011; Steuber et al., 2011). A previous study using this model indicated that more irregular Purkinje cell spike trains should be less effective, on average, than regular spike trains at inhibiting postsynaptic targets (Luthman et al., 2011). We analyzed the sensitivity of this finding to the choice of specific model parameters.
The model consisted of a multi-compartmental reconstruction of a Purkinje cell target neuron in the deep cerebellar nucleus (Luthman et al., 2011; Steuber et al., 2011). The target neuron received inhibition from 50 Purkinje cells (Person and Raman, 2012a), each firing spontaneously at 60 sp/s (CV = 0.5), and excitation from 150 mossy fibers, each firing spontaneously at 20 sp/s (CV = 1) (Figure 7A), with the inhibitory synapses exhibiting short-term depression as modeled by Shin et al. (2007). The model target neuron also contained Hodgkin-Huxley style ion channel conductances based on experimental measurements, as in the original model (see Materials and methods).
Biophysical model: During simulated optogenetic stimulation, impact of spike irregularity is sensitive to the excitation/inhibition ratio.
(A) Schematic showing elements in the model. A biophysical model of a Purkinje cell target neuron received inhibitory synaptic input from 50 Purkinje cells and excitatory synaptic input from 150 mossy fibers. The effect of Purkinje cell stimulation on the output of the model target neuron was compared with the experimentally observed eye movement responses to Purkinje cell stimulation. (B) Spike trains in the 50 model Purkinje cells during simulated optogenetic stimulation (100 Hz regular and irregular stimulation illustrated here) were composed of spontaneous spikes plus stimulus-driven spikes. (C) Target neuron output in response to simulated optogenetic stimulation, for the model with all original parameters including short-term synaptic depression (STD) at the Purkinje cell-to-target neuron synapses (C1) and for the same model but without STD (C2). Note different scales of vertical axes in C1 and C2. Gray traces show STD of the inhibitory conductance in the model during 50 Hz stimulation. Mean target neuron spike rate during the 500 ms stimulus train is plotted for a range of different stimulation rates and levels of irregularity (left). In this and subsequent panels, the firing rate of the model target neuron is plotted with the y-axis inverted (lower firing rate plotted higher on the y-axis) since Purkinje activation drives a decrease in target neuron activity below the spontaneous rate (Lisberger et al., 1994b), which in turn drives eye movements (Dufossé et al., 1977). Voltage traces (right) show the membrane potential of the model target neuron during 100 Hz regular (top) or irregular (bottom) stimulation. (D) Irregularity impact index (Iirreg, see text) for models with different strengths of excitatory (E) and inhibitory (I) conductance (relative to the original model, indicated by solid box), with short-term depression (D1) or without short-term depression (D2) of the Purkinje cell-to-target neuron synapses. The size and color of the circle reflects the value of Iirreg for each set of model E/I parameters, with larger circles representing a larger difference in the impact of regular versus irregular Purkinje cell stimulus trains on the mean target neuron output (positive values reflect a bigger impact of regular trains). Gray shading indicates model parameters for which Iirreg < 0.05 (compare with gray shading in Figure 8A). Dashed boxes indicate parameters that yielded a close fit to experimental results, shown in (E). (E) Mean target neuron output averaged across the 500 ms stimulus trains (left); the moment-to-moment trajectory of the model output (right, gray) and actual eye velocity from an example mouse (right, black) during 60 Hz stimulus trains, for models with new E/I parameters (indicated by dashed boxes in panel D), either with short-term depression (E1) or without short-term depression (E2).
To simulate the optogenetically-driven Purkinje cell activity recorded in vivo, stimulus-driven Purkinje cell spikes following the same regular and irregular stimulus patterns used in the stimulation experiments were superimposed on a background of spontaneous spiking at 60 sp/s (Figure 7B). Each stimulus-driven Purkinje cell spike was delayed by a random amount (1.24 ms ± 1.36 ms, mean ± STD for a Gaussian distribution truncated at 0 ms) relative to the common stimulus time to mimic the variability in spike latencies observed in vivo (median: 1.24 ± 0.07 ms, standard deviation: 1.36 ± 0.17 ms, n = 13, Figure 3B). The net impact of Purkinje cell stimulation was quantified by computing the spike rate of the model target neuron, averaged over the 500 ms stimulus window, for each stimulus train. The impact of stimulus trains with different rates and irregularity on target neuron output were compared with the empirical effects of the same stimulus trains on eye movements.
When model parameters were identical to those previously published (Luthman et al., 2011), the model predicted that irregular stimulus trains (CV = 1) would have substantially smaller net impact on mean target neuron output than regular stimulus trains (CV = 0) (Figure 7C1), as previously reported for simulations of spontaneous Purkinje cell spiking with different levels of irregularity. This prediction was inconsistent with our experimental observation of similar net impact of regular and irregular spike trains on eye movements (Figure 4); thus the in vivo observations could not be explained by the previously chosen model parameters. Those parameters had been selected, wherever possible, to match biophysical parameters reported in the experimental literature. However, the values reported for some biophysical parameters differ across experimental studies or cerebellar regions, or are otherwise not well constrained. We found that changes to specific model parameters within a biologically realistic range allowed the model to reproduce the experimental results.
One parameter for which different values have been reported in the experimental literature is the amount of short-term plasticity at the synapses from Purkinje cells to their target neurons, which was previously identified as a potential mechanism by which Purkinje cell spike irregularity might influence the activity of the target neurons. Studies in young rodents reported strong (Pedroarena and Schwarz, 2003) or moderate (Telgkamp and Raman, 2002; Telgkamp et al., 2004) short-term depression at these synapses. Such short-term plasticity was previously predicted to cause more irregular spike trains to have reduced net impact on their targets (Luthman et al., 2011), contrary to our experimental observations. However, it was recently discovered that short-term plasticity at these synapses is developmentally regulated, such that synaptic transmission in adult mice is remarkably independent of spike rate (Turecek et al., 2016; Turecek et al., 2017). Our experiments were performed in adult mice; therefore, we eliminated short-term depression in the model. However, elimination of short-term depression was not sufficient to allow the model to reproduce the experimentally observed responses to optogenetic stimulus trains (Figure 7C2). Even without short-term depression, the model predicted smaller net impact of irregular than regular stimulus trains, contrary to the experimental observations.
A second mechanism through which the irregularity of Purkinje cell stimulation could influence target neuron spiking is through the creation of synchronous gaps in inhibitory synaptic transmission (Person and Raman, 2012a). At high stimulus rates, the regular interstimulus intervals were too short to permit the model postsynaptic neuron to reliably reach threshold and fire a spike before the next synchronous inhibitory input arrived (Figure 7C, top right). In contrast, highly irregular stimulus trains at the same mean frequency contained a wide range of interstimulus intervals, including some that were sufficiently long to permit postsynaptic firing (Figure 7C, bottom right). This observation suggested that the irregularity of Purkinje cell stimulation might influence the mean output of the target neurons whenever the strength of Purkinje cell synaptic inhibition was large enough, relative to the strength of excitation, so that one stimulus pulse to the Purkinje cells could suppress spiking in the target neuron for the duration of the mean interstimulus interval. In contrast, floccular Purkinje cell target neurons in the vestibular nuclei are able to sustain high spontaneous firing rates of ~50–120 sp/s despite incessant Purkinje cell inhibition (Lisberger et al., 1994a; Zhang et al., 1995b; Zhang et al., 1995a; Lisberger et al., 1994b; Beraneck and Cullen, 2007; Bagnall et al., 2008). Therefore, we systematically varied the excitatory and inhibitory conductances in the model target neuron, while holding other parameters constant, to test how the relative strength of excitation and inhibition (the E/I balance) received by the target neuron influenced the effects of Purkinje cell irregularity.
To summarize the net impact of stimulus irregularity on target neuron output across different model parameters, we introduce a metric, Iirreg, that captures the normalized difference between the mean target neuron response to regular and irregular stimulation at different frequencies:
Iirreg=1Nfreqs∑i=1Nfreqsriirreg−riregrrange
where rireg is the mean target neuron rate in response to regular stimulation (CV = 0) at frequency i, riirreg is the mean response to irregular stimulation (CV = 1) at the same frequency, and rrange is the range of mean target neuron rates observed across the entire set of stimulus trains plus spontaneous activity (max – min). Iirreg provides a measure of the effect of irregularity on the overall efficacy of spike trains. Identical mean target neuron responses to regular and irregular stimulation at each frequency would produce an Iirreg value of 0, whereas larger positive values of Iirreg represent less effective inhibition of target neuron activity by irregular than regular stimulation (riirreg >rireg). Therefore, larger values of Iirreg indicate that stimulus irregularity has a greater impact on the control of motor output.
During simulated optogenetic stimulation, the balance of excitatory and inhibitory conductances was a key determinant of whether the net impact of regular and irregular stimulus trains on downstream activity was different, as quantified by Iirreg . In models with higher E/I ratios, the efficacy of the Purkinje cell spike trains had little dependence on spike irregularity, reflected by small values of Iirreg (Figure 7D, small symbols). Moreover, there were models with small Iirreg that closely matched the dynamics of the eye movements observed experimentally in response to the optogenetic stimulus trains (Figure 7E). Thus, although previous work with the same biophysical model contended that spike irregularity should affect downstream processing of the Purkinje cells' output (Luthman et al., 2011), the biophysics of the Purkinje cell-target neuron synapses are also consistent with a negligible effect of Purkinje cell spike irregularity. Indeed, the original model parameters seem to lie in a small region of E/I parameter space where the effects of irregularity are near maximal (Figure 7, Figure 8).
Biophysical model: Reduced impact of irregularity during asynchronous activity.
(A) Impact of irregularity (Iirreg) during asynchronous Purkinje cell activity for biophysical models without STD. The color scale for Iirreg is the same as in Figure 7, while the size of the corresponding circles is expanded two-fold to improve visibility of the much smaller differences between models. Gray shading indicates Iirreg < 0.05, for comparison with Figure 7D. (B) The impact of irregularity during the more synchronous Purkinje cell activity of simulated optogenetic stimulation ('Opto synchronous'), compared with the impact of irregularity when the same spike trains were shuffled to provide asynchronous Purkinje cell activation in the same model ('Asynchronous'). Note that even in the Opto synchronous condition, there was considerable spike asynchrony due to the independent, spontaneous activity in each Purkinje cell and variation in the latencies of the spikes driven by each simulated light pulse.
The biophysical model was also used to examine how the effects of spike irregularity in individual Purkinje cells might be influenced by spike synchrony across Purkinje cells. Optogenetic stimulation had the advantage of allowing independent experimental manipulation of spike rate and irregularity, but it had the disadvantage of driving spiking that was almost certainly more synchronous across the Purkinje cell population than present during natural sensorimotor signal processing (Bell and Grimm, 1969; Bell and Kawasaki, 1972; Ebner and Bloedel, 1981; Shin and De Schutter, 2006; Heck et al., 2007; de Solages et al., 2008; Wise et al., 2010). The biophysical model was used to predict the impact of Purkinje cell spike irregularity under more natural conditions of less Purkinje cell synchrony than present during optogenetic stimulation. Asynchronous spike trains were generated with the same statistics as the 'synchronous' simulated optogenetic stimulus-driven spike trains by shifting the stimulus-driven spikes in each model Purkinje cell by a random, fixed amount between 0 and 500 ms, with a different random shift for each Purkinje cell in the model (Figure 8). For every combination of model parameters, the net impact of irregularity, Iirreg, was smaller for asynchronous Purkinje cell activity than for the more synchronous activity present during simulated optogenetic stimulation (Figure 8B). These smaller values of Iirreg for asynchronous rather than synchronous conditions indicate that any effect of spike irregularity on the mean target neuron output under more natural, asynchronous conditions should be less than that observed experimentally during more synchronous stimulation. Since the measured impact of Purkinje cell irregularity on mean eye velocity was not significant during synchronous optogenetic stimulation, the model suggests that such irregularity would have a similarly negligible impact under more natural, asynchronous conditions. Taken together, the recording, stimulation, and modeling results make a strong case that floccular Purkinje cells control eye movements with a rapid population rate code, with no evidence for an additional effect of spike irregularity.
Random walk model of the effect of input variance on target neuron spiking
The biophysical model described above has many parameters, making it impractical to assess how and why each parameter may affect the sensitivity of the model to Purkinje cell spike irregularity. A much simpler, random walk model (Gerstein and Mandelbrot, 1964; Shadlen and Newsome, 1998; Salinas and Sejnowski, 2000) reveals that a range of relationships between spike irregularity and mean target neuron output can arise from even the most basic features of a neuron: a spike threshold, a post-spike reset membrane potential, and a minimum membrane potential, combined with stochastic inputs. In this model, the membrane potential of a neuron is driven by a stochastic input, which represents the sum of all excitatory, inhibitory, and intrinsic currents. The input at each time step is perfectly integrated by the membrane potential until it reaches a threshold, at which point it fires a spike and the membrane potential is reset to a predetermined value (Figure 9). A key parameter in the model is the moment-to-moment variability of the stochastic input around its mean value. The irregularity and synchrony of excitatory and inhibitory synaptic inputs are not explicitly modeled, but each can be considered as increasing the variance of the stochastic input representing the net membrane current (Figure 6, Figure 10).
Random walk model: Input variability can increase or decrease target neuron firing.
Random walk simulation of a simple integrate-and-fire neuron receiving stochastic inputs with mean μ and standard deviation σ. Additional parameters are the threshold voltage Vthresh = 40 steps (arbitrary units), reset voltage Vreset = 20 steps, minimum voltage Vmin = 0 and time step dt = 1 ms (Salinas and Sejnowski, 2000). Black: original parameters (μ = 1.5; Vmin = 0); red: increased E/I ratio ('Higher E/I', μ = 2.5), dark blue: balanced excitation and inhibition ('Balanced E/I', μ = 0); light blue: membrane potential floor eliminated ('No minimum potential', Vmin = –infinity, equivalent to raising Vthresh and Vreset very far from Vmin). (A) Example traces showing the membrane potential in model neurons for different levels of input variability (σ = 2, 7, 15 steps). At each time step, the voltage changes by an amount drawn from a normal distribution with mean μ and standard deviation σ. Upon crossing Vthresh (top gray line), the voltage is automatically lowered to Vreset (middle gray line) (vertical lines are added to visualize spike times). There is a reflecting floor at Vmin (bottom gray line, not present for 'No reflecting barrier'). (B) Numerical simulations (dots) and approximate analytic predictions (lines) of the firing rate output of model neurons receiving stochastic inputs with mean μ and standard deviation σ. In both the original and 'Higher E/I' simulations, there is a range of σ where small changes in variability have little effect on mean output rates (the range where the curves are approximately flat). Increasing the E/I balance shifts this flat region to the right.
Effects of spike irregularity and synchrony on motor output over short and long timescales.
Our recording, stimulation, and modeling results indicate that Purkinje cells in the cerebellar flocculus control motor output with a rapid rate code. (A) Schematic of the transformation from Purkinje cells to motor output. A population of Purkinje cells (and excitatory neurons, not shown) converges on each target neuron. A population of target neurons drive eye movements. (B) The rate, irregularity, and synchrony of spike trains in individual Purkinje cells can each influence the population spike rate. The mean and variability of the Purkinje cell population rate both affect motor output through a rapid rate code. (C) Effects of Purkinje cell spike irregularity and synchrony on the Purkinje cell population spike rate (top), and target neuron spike rate, representing the eye velocity motor command (bottom). The mean population spike rate in a given time interval—either a few milliseconds or hundreds of milliseconds—can predict the mean eye velocity in that same time interval. At short timescales of a few milliseconds, the irregularity and synchrony of spiking in individual Purkinje cells can affect the population spike rate and hence the moment-to-moment motor output. At longer timescales of a few hundred milliseconds, the same mean spike rate elicits the same mean eye velocity (gray lines), regardless of the level of irregularity or synchrony.
Even in the extremely simple random walk model, the effect of increased input variance on the target neuron spike rate depended on the location in parameter space (Figure 9). A well-known prior result (Salinas and Sejnowski, 2000) is that an increase in input variance can drive a higher spike rate in the target neuron (Figure 9B, positive slopes). This would correspond, for example, to an increase in Purkinje cell irregularity or synchrony creating more gaps in inhibition that provide a 'window of opportunity' for spiking, thereby making the Purkinje cells less effective at inhibiting spiking in their target neurons. A less recognized finding from the random walk model is that it can also exhibit the opposite behavior, whereby an increase in input variance can decrease spike rate in the target neuron (Figure 9B, negative slopes; see also Salinas and Sejnowski, 2000). Indeed, with other model parameters held constant, as input variance increases from zero, the spike rate can first decrease and then increase (Figure 9B, black and red). In the transition between these two regimes, changes in input variance within a certain, intermediate range have minimal effect on spike rate in the target neuron (Figure 9B, flat portion of the curves).
The ability of increased input variance to either increase or decrease firing in the target neuron can be understood by considering two extreme cases. In the case where excitation and inhibition are perfectly balanced (mean input is zero), the target neuron will never reach threshold if there is no input variance. Thus, when excitation and inhibition are balanced, increasing the input variance around the mean of zero increases the target neuron rate (Figure 9, dark blue; monotonically increasing). A second extreme case is where the mean input is excitatory, but there is no limit to the hyperpolarization of the membrane potential. In the random walk model, this limit is implemented as a 'floor' (Vmin) below which additional inhibitory input has no effect, and which serves to keep the membrane potential relatively close to the threshold. If this floor is removed, then a variable input can cause the membrane potential to wander far from threshold, hence increasing input variance under these conditions decreases the target neuron output on average (Figure 9, light blue; monotonically decreasing). Spontaneously active neurons, such as the targets of floccular Purkinje cells, operate in a regime between these two extreme cases, because all neurons have biophysical limits on their membrane potential, and spontaneously active neurons also have net positive mean excitatory drive. In this regime, increasing the input variance can decrease, increase, or have minimal effect on the mean target neuron spike rate, as illustrated by the non-monotonic curves describing target neuron spike rate as a function of input variance (Figure 9, red and black). Notably, a change in the mean input (e.g. E/I ratio) can alter the sensitivity of spike rate to input variance (Figure 9B, steepness of red vs. black curve), and shift the absolute level of input variance at which there is a transition from a negative to positive dependence of spike rate on input variance.
This simple simulation demonstrates that biophysical complexity is not necessary to create different relationships between input variance and output spike rate. Instead, the statistics of the random walk itself can yield either an increase or a decrease in output spike rate with an increase in input variance. Our experiments appear to have uncovered a biological example of an overlooked region of parameter space, where changes in synaptic input variability within the range experienced during normal behavior have little impact and hence do not interfere with the rate code for motor output.
The analytical power of the oculomotor system provided an opportunity to test the idea that cerebellar Purkinje cells employ a multiplexed rate code and temporal code to control motor behavior. Previous experimental and modeling studies of ataxia have suggested that pathological changes in the irregularity of spiking in Purkinje cells influence the responses of downstream neurons and thus behavior (reviewed in De Zeeuw et al., 2011). Inspired by these studies, the current research used complementary recording, stimulation, and computational modeling approaches to analyze whether spike irregularity is a component of the neural code used by Purkinje cells to control downstream neurons during normal sensorimotor signal processing and behavior.
The results suggest that the transformation of Purkinje cell activity into motor output is closely approximated by a rapid population rate code (Figure 10). Recordings of natural spike trains in Purkinje cells of the cerebellar flocculus during normal oculomotor behavior revealed an intriguing correlation between mean spike irregularity and mean gaze velocity, as also observed for mean spike rate. However, natural, trial-to-trial variations in the eye movement responses to repetitions of the same stimuli could be predicted from fluctuations in spike rate, but not from fluctuations in spike irregularity (Figure 2). The ability to predict fluctuations in behavior from the spike rate recorded in a single Purkinje cell suggests that the fluctuations in spike rate are shared across a large fraction of the population of Purkinje cells that control eye movements (see also Chaisanguanthum et al., 2014). In contrast, the lack of correlation between fluctuations in CV2 and eye velocity could indicate that 1) the effect of spike irregularity in a single neuron is too small to detect, and fluctuations in spike irregularity are not shared across the population of Purkinje cells, or 2) spike irregularity does not influence eye velocity. The results from the optogenetic stimulation experiments favor the latter interpretation, since the optogenetic stimulus trains drove robust changes in spike irregularity across a large population of stimulated Purkinje cells, yet there was no difference in the mean eye velocity during regular and irregular spike trains after controlling for spike rate. The levels of synchrony across the Purkinje cell population during optogenetic stimulation were almost certainly higher than during natural behavior, however, the biophysical model predicts even smaller effects of spike irregularity under conditions of lower synchrony, consistent with the recordings made under conditions of natural levels of synchrony (Figure 2), which also yielded no evidence for an impact of spike irregularity. Taken together, the convergent evidence from the complementary recording, stimulation, and modeling approaches indicates that the irregularity of spiking in Purkinje cells is not a significant component of the code used by the cerebellar flocculus to control normal eye movements. The recording and stimulation results can be fully accounted for by the Purkinje cells controlling eye movements primarily or exclusively via a rate code.
A remarkably rapid rate code for motor control
Linear rate coding
Previous studies have demonstrated that electrical or optogenetic manipulation of Purkinje cell activity can drive motor responses, with bigger behavioral responses for higher intensity stimulation (Ron and Robinson, 1973; Belknap and Noda, 1987; Lisberger, 1994; Wada et al., 2014; Nguyen-Vu et al., 2013; Heiney et al., 2014; Lee et al., 2015; Stahl et al., 2015; Sarnaik and Raman, 2018). We extended this work by showing a roughly linear relationship between Purkinje cell spike rate and behavior for optogenetic stimulation-driven spike rates from 0 to 100 sp/s above the spontaneous rate (Figure 4E), consistent with the linear coding described in recordings of neural activity during oculomotor behavior (Figure 1C; Shidara and Kawano, 1993; Lisberger, 1994; Kahlon and Lisberger, 1999; Medina and Lisberger, 2007; Medina and Lisberger, 2009; Katoh et al., 2015; Hong et al., 2016; Herzfeld et al., 2015; Sun et al., 2017; reviewed in Raymond and Medina, 2018).
Rapid rate coding
The speed of the rate code conveyed by Purkinje cells for controlling eye movements is remarkable. Previous work has shown that inhibitory synaptic transmission between Purkinje cells and their postsynaptic targets is fast, with a synaptic time constant of 2 ms (Najac and Raman, 2015). We found that this speed is largely maintained in the downstream oculomotor circuitry, which includes signaling from the flocculus target neurons in the vestibular nuclei to their interneuron and motor neuron targets in the abducens nucleus, and the effects of the latter on the oculomotor plant (reviewed in Highstein et al., 2004). Discrete eye movement responses could be observed in response to each 1 ms optogenetic stimulus pulse, for stimulus frequencies at least as high as 100 Hz (Figure 4). The mutual information between Purkinje cell rate and eye velocity peaked for a temporal smoothing window of 3–5 ms (Figure 5A). Likewise, the linear temporal filter describing the transformation of Purkinje cell rate into eye velocity had a width of ~5 ms (width at half-amplitude of the initial transient; Figure 5B). Thus, the population spike rate in the floccular Purkinje cells appears to be read out by the downstream oculomotor circuitry on a timescale of 3–5 ms. This is less than the typical ISI in an individual Purkinje cell, but is a reasonable timescale for considering the population spike rate in the ~50 Purkinje cells converging on a given target, which will collectively emit 10 or more spikes, on average, per 5 ms interval; likewise, 3–5 ms is a reasonable timescale for considering spike rate in the full population of Purkinje cells controlling eye movements. Such rapid rate coding is likely not unique to the oculomotor system; there is evidence that other motor circuits can transmit information on a similar timescale (Tang et al., 2014; Srivastava et al., 2017; Brown and Raman, 2018).
Rapid rate coding can endow sensitivity to spike irregularity and synchrony
The rapid speed at which the population spike rate is read out could endow the circuit with sensitivity to any spiking statistics that alter the population rate over short timescales, including spiking statistics that are typically associated with temporal coding, such as spike irregularity and synchrony (Figure 10). The convergence of ~50 Purkinje cells onto each target neuron can average out the 'noisiness' of signals carried by the spike trains of individual neurons. Our results indicate that this averaging out needs to occur on a timescale of 3–5 ms, because variations in the population rate get faithfully transmitted all the way to the behavior with this temporal resolution (Figure 5, Figure 10C). This provides a mechanism by which the high level of Purkinje cell spike irregularity in ataxia (CV of 0.7–2.3 in ataxic mice compared to 0.4–0.6 in control mice; Hoebeek et al., 2005; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015) could degrade the accuracy of movements: by degrading the accuracy and precision of the motor commands carried by the population spike rate (Figure 6). In contrast, smaller variations in spike irregularity within the normal physiological range may be well tolerated because they have minimal impact on the population spike rate. Similarly, Purkinje cell synchrony (Bell and Grimm, 1969; Bell and Kawasaki, 1972; Ebner and Bloedel, 1981; Shin and De Schutter, 2006; Heck et al., 2007; de Solages et al., 2008; Wise et al., 2010; Person and Raman, 2012a; Sarnaik and Raman, 2018; Brown and Raman, 2018; Tang et al., 2019) can be reframed as rapid changes in the Purkinje cell population firing rate on a timescale of a few milliseconds, which could be transmitted downstream via the rapid population rate code for eye velocity. Thus, rapid fluctuations in the population rate, which can be generated by spike irregularity or synchrony, can be read out as rapid fluctuations in the intended motor command (Figure 10), allowing spike irregularity and synchrony to influence behavior via the rate code.
No evidence for additional influence of spike irregularity
Extremely rapid rate coding might seem to blur the line between rate coding and temporal coding, but it is important to distinguish rapid rate coding from true temporal coding. Although the term 'temporal code' is sometimes used to describe changes in spike rate co-occurring with changes in a dynamic stimulus or behavior (e.g. Gooler and Feng, 1992), we would reserve the term 'temporal coding' to refer to an influence of the temporal statistics of spiking that cannot be accounted for by the population spike rate computed over a biologically relevant timescale (Theunissen and Miller, 1995). We found no evidence for temporal coding in the latter, more rigorous sense of the term. Temporal coding could potentially take many forms, and we evaluated just one form based on spike irregularity, hence our results do not rule out other forms of temporal coding in the cerebellar circuit. Our experiments were designed specifically to detect effects of spike irregularity above and beyond what could be accounted for by a population rate code for eye velocity, and we found no evidence for such effects.
Previous work had suggested that more irregular spiking in Purkinje cells would be less effective in influencing downstream neurons than more regular spiking (Hoebeek et al., 2005; Luthman et al., 2011). Therefore, we initially expected that a more irregular spike train in a floccular Purkinje cell would drive a smaller eye movement than a more regular spike train at the same mean rate. Contrary to this prediction, mean eye velocity, averaged across the 500 ms optogenetic stimulation interval, was indistinguishable during the regular and irregular stimulus trains, after controlling for mean spike rate. Within the 500 ms stimulation interval, the regular and irregular stimulus trains elicited different eye movement trajectories on a moment-to-moment basis; however, these differences were well explained by the different trajectories of the instantaneous Purkinje cell population firing rate during the regular versus irregular trains (Figure 10). The mean spike rate in a given time interval—either a few milliseconds or the entire 500 ms train—could predict the mean eye velocity in that same time interval, with no additional effect of irregularity within that interval. Thus the irregularity of Purkinje cell spiking in the flocculus can affect the fine temporal structure of movement through a rapid rate code, without the need to invoke a separate temporal code.
Potential for different coding strategies in different regions of the cerebellum
It is possible that the impact of spike irregularity in Purkinje cells could vary across different zones or microzones of the cerebellum. There is substantial variation in the gene expression, firing rates, and properties of synaptic plasticity in the Purkinje cells in different areas of the cerebellar cortex (Suvrathan et al., 2016; Cerminara et al., 2015; Wadiche and Jahr, 2005; Kim et al., 2012; Witter and De Zeeuw, 2015), and in the Purkinje cells' target neurons in different deep cerebellar and vestibular nuclei (Chan-Palay, 1977; Sugihara and Shinoda, 2004; Sugihara, 2011; Sekirnjak and du Lac, 2006; Pugh and Raman, 2006; Bagnall et al., 2007; McElvain et al., 2010; Shin et al., 2011; Low et al., 2018). Our biophysical modeling indicates that variations in model parameters within a biologically plausible range could determine whether spike irregularity either does or does not influence the transmission of information by the Purkinje cells. Although recording and stimulation results indicate that the cerebellar flocculus operates in a region of parameter space where the impact of spike irregularity is negligible, even during highly synchronous population activity, the model demonstrates that changing a single parameter, such as the ratio of excitation to inhibition, could create sensitivity to spike irregularity. Thus, other parts of the cerebellum may operate in regions of parameter space where spike irregularity has an impact beyond what can be accounted for by the rapid rate code. Some support for this possibility is provided by a recent report that regular, synchronous optogenetic stimulus trains delivered to Purkinje cells of the cerebellar lobulus simplex were less likely to perturb ongoing locomotion than continuous optogenetic stimulation, which elicits less regular, less synchronous spiking (Sarnaik and Raman, 2018). However, the interpretation of such results will require careful consideration of the effects on the Purkinje cell population spike rate in the behaviorally relevant, causal time window. Our finding that the population spike rate can influence behavior with high temporal precision demonstrates that a clear understanding of how the rate code influences behavior on a moment-to-moment basis is critical for evaluating the possibility that additional, temporal coding might also influence behavior. Such analyses are more challenging for complex behaviors such as locomotion, hence additional research is required to determine what, if any, role spike irregularity or other forms of temporal coding play in the cerebellar control of such behaviors.
Implications for understanding the neural code
The ability of the brain to encode sensory information, process it, and generate motor responses depends on the neural code(s) used to transmit information. Thus, understanding how information is transmitted through the rate and timing of spikes is central to understanding neural computation, and can also guide the development of more effective interventions to treat brain disorders (Birdno et al., 2008; Birdno et al., 2012; Summerson et al., 2015; McConnell et al., 2016; Karamintziou et al., 2016). There has been extensive analysis of how temporal patterns of neural activity encode information in different brain areas (reviewed in Singer, 1993; Borst and Theunissen, 1999; Wang et al., 2008; Ainsworth et al., 2012; Gire et al., 2013; Uchida et al., 2014). However, in most mammalian circuits, it has been difficult to determine whether and how information encoded in the precise timing of spikes is read out, because the link between neural activity and behavior is typically too complex or remote. We leveraged the close link between floccular Purkinje cell activity and eye movements to analyze the contribution of spike rate and irregularity to the behavioral output, and found evidence only for rapid rate coding. Nevertheless, our modeling results indicate that biologically realistic variations in parameters could allow the precise temporal pattern of presynaptic activity to influence the downstream response. Thus, the extent to which information encoded in spike timing gets transmitted to the downstream circuitry may vary across synapses, and might even vary dynamically at the same synapses depending on the behavioral state.
Key resources table
Reagent type (species)
or resource
Source or reference
Strain, strain background (Mus musculus) ChR2(H134R)-EYFP Jackson Laboratory RRID:IMSR_JAX:024109
Strain, strain background (Mus musculus) (Pcp2-cre)3555 Jdhu/J Jackson Laboratory RRID:IMSR_JAX:010536
Software, algorithm NEURON biophysical model by Luthman et al., 2011. ModelDB 144523
Electrophysiology in monkeys and mice during oculomotor behavior
Recording procedure in monkeys and mice during oculomotor behavior
Extracellular recordings were made from Purkinje cells in the cerebellar flocculus and ventral paraflocculus of four adult male rhesus monkeys (data previously published in Raymond and Lisberger, 1997; Raymond and Lisberger, 1998; Kimpo et al., 2014 and Ke et al., 2009) and the flocculus of 63 adult C57BL/6 mice (data previously published in Katoh et al., 2015) during eye movement responses to a range of different combinations of vestibular and visual stimuli. Eye movements were recorded with the eye coil method at 500 Hz. Vestibular stimuli were provided by using a turntable to passively rotate the head-fixed animal about an earth-vertical axis. For monkeys, visual stimuli were provided by horizontal motion of a small bright spot (target, T, subtending 0.5° of visual angle) and/or high-contrast background (BG, a 20°×30° grid of 1.5°×1.5° black and white squares) projected onto a tangent screen that was 114 cm in front of the eyes. For mice, the visual stimulus was provided by a striped hemispherical dome with vertical black and white stripes, each subtending 7.5° of visual angle, which surrounded the animal.
All four monkeys were tested with the following set of visual-vestibular stimuli: (1) sinusoidal motion of the visual target alone at 0.5 Hz, ±10°/s to ±31.4°/s to evoke visual tracking (smooth pursuit) eye movements; (2) sinusoidal motion of the head and visual target together at 0.5 Hz, ±10°/s to ±31.4°/s to evoke VOR cancellation (attenuation of the normal VOR eye movements). In addition, two of the monkeys (monkeys D and E) were tested with the following set of visual-vestibular stimuli: (3) steps of constant head velocity at 15°/s for 500 ms, with the visual target and background moving together with the head ('×0 step') or (4) opposite to the head ('×2 step') (Raymond and Lisberger, 1998; Raymond and Lisberger, 1997; Kimpo et al., 2014). The other two monkeys (monkeys C and L) were tested with the following visual-vestibular stimuli in addition to smooth pursuit and VOR cancellation: sinusoidal vestibular stimulation at 0.5 Hz, ±10°/s in combination with motion of the visual target and background, where the target and the background moved together with each other and with the vestibular stimulus (5, '×0T/×0BG') or opposite to the vestibular stimulus (6, '×2T/×2BG'); or where the target and the background moved opposite to each other with either the target (7, '×0T/×2BG') or the background (8, '×2T/×0BG') moving together with the head; or where the background was stationary but the target moved either together with the head (9, '×0T/×1BG') or opposite to the head (10, '×2T/×1BG') (Ke et al., 2009). Data from monkeys D and E are plotted in Figure 1A,B. Data from all four monkeys were plotted in Figure 1C–E (top graphs), where each color represents a single condition as described above. In total, the following number of EiHi cells were recorded and plotted in Figure 1C–E for each condition listed above: (1) n = 120; (2) 120; (3) 26; (4) 27; (5) 50; (6) 38; (7) 47; (8) 47; (9) 49; (10) 38; spontaneous: 33. Data from smooth pursuit and VOR cancellation in all four monkeys were used in the residual analysis (Figure 2).
Mice were tested with (1) sinusoidal motion of the striped dome alone (1 Hz, ±10°/s) to evoke the optokinetic reflex ('visual tracking') and (2) sinusoidal motion of the striped dome together with the animal (1 Hz, ±10°/s) to evoke VOR cancellation (n = 33 EiHi cells). Spontaneous activity was recorded in a subset of these cells (n = 8).
Trial-averaged analysis of neural activity in monkeys and mice during oculomotor behavior
The relationship between Purkinje cell simple spike activity and eye movements during oculomotor behavior was analyzed using MATLAB (The MathWorks, Inc). Instantaneous spike rate was computed by convolving each spike with a Gaussian kernel with 10 ms standard deviation. Instantaneous local irregularity was computed by first calculating the CV2 for each pair of ISIs according to Equation 1, where CV2i is calculated from the three spike times ti-1, ti, and ti+1. For each pair of ISIs, the instantaneous local irregularity, CV2(t), was then set to the value of CV2i from time ti−(ti−ti−1)/2 to ti+(ti+1−ti)/2.
Purkinje cells in the flocculus display a range of responses during horizontal eye movements. We focused on Purkinje cells with the most common directional preference in the flocculus across species: cells that increase their firing during both ipsiversive eye motion (Ei; peak firing within ±90° of peak ipsiversive eye velocity during visual tracking), and ipsiversive head motion (Hi; peak firing within ±90° of peak ipsiversive head velocity during VOR cancellation), and which therefore encode ipsiversive gaze velocity (EiHi cells; Miles et al., 1980; Lisberger, 1994; Raymond and Lisberger, 1997; Katoh et al., 2015). Purkinje cells in the flocculus that exhibited other preferences for head or eye motion (increased firing for contraversive eye or head motion, or no sensitivity to one of the two; non-EiHi cells) were tested for antiphasic modulation of spike rate and irregularity during oculomotor behaviors (Figure 1—figure supplement 2), however, all other analyses were performed only on the EiHi Purkinje cells, for which the largest number of cells were recorded.
Trial-averaged neural and behavioral responses were calculated by averaging eye velocity, gaze velocity, spike rate, and instantaneous CV2 across trials for each cell, and then across cells (Figure 1A, Figure 1—figure supplement 1), where a 'trial' consisted of one cycle of a sinusoidal stimulus, or, for 'step' stimuli, a set of one ipsiversive and one contraversive stimulus. To examine the relationship between gaze velocity and spike rate, gaze velocity was divided into evenly spaced bins (bin width 2°/s), and the average spike rate was calculated in each bin by first averaging within a cell (Figure 1B, top), then across the population of EiHi Purkinje cells (Figure 1C). Similarly, the relationship between gaze velocity and spike irregularity was analyzed by binning gaze velocity, then computing the average CV2 for each gaze velocity bin, first in each cell (Figure 1B, bottom), and then across the population (Figure 1D). The correlation coefficient was calculated on the binned data for each cell individually, and then averaged across cells. The hypothesis that each correlation coefficient was significantly different than zero was assessed using a one sample t-test. Finally, the relationship between spike irregularity and spike rate was summarized by calculating the instantaneous CV2 and spike rate at each time within a trial, averaged across trials for each cell, then averaged across cells, and finally comparing plotting spike rate versus CV2 for each time within the trial (Figure 1E).
Simulated inhomogeneous Poisson process
To determine whether the observed inverse relationship between spike rate and irregularity could be generated by a inhomogeneous Poisson process modified by a refractory period (Holt et al., 1996), the average rate of Purkinje cell activity recorded in monkeys during smooth pursuit was calculated by averaging across all trials and all cells. An artificial spike train was then generated to match this average firing rate using an inhomogeneous Poisson process with an absolute refractory period. Artificial interspike intervals were drawn from an exponential distribution offset by the duration of the refractory period. The method of thinning was then used to match firing rates: artificial spikes were removed with probability inversely proportional to the firing rate (Lewis and Shedler, 1979). The artificial spike trains and real spike trains were then analyzed identically. To calculate mean firing rate, spikes were convolved with a 10 ms sigma Gaussian filter and averaged across trials. To calculate mean CV2, the instantaneous CV2 was calculated as above and averaged across trials. The instantaneous relationship between firing rate and CV2 was compared by binning all pairs of ISIs based on their mean firing rate, Ratei=2/(ISIi+ISIi+1), and calculating the mean CV2 for all ISI pairs in each firing rate bin according to Equation 1 (Holt et al., 1996).
Moment-to-moment analysis of neural activity in monkeys and mice during oculomotor behavior
The moment-to-moment fluctuations in neural activity and eye movements during oculomotor behavior were analyzed by first binning the raw spike rate, spike irregularity (CV2), and eye velocity in 50 ms time bins. This bin width was chosen to be short enough to capture fluctuations in eye velocity, and long enough to allow any measured fluctuations in Purkinje cell activity to impact eye velocity, given delays arising from the downstream neural circuitry and the oculomotor plant. Residual spike rate, CV2, and eye velocity were calculated by subtracting the corresponding cycle-averaged spike rate, CV2, and eye velocity from the binned response on each cycle of the stimulus. Residuals were calculated for all EiHi cells during the visual tracking and VOR cancellation conditions, which were recorded for all cells in both monkeys and mice. Since there was negligible variation in the vestibular stimulus (head velocity) from trial-to-trial, the residual eye velocity was equivalent to residual gaze velocity.
The ability of residual spike rate and residual spike irregularity to predict residual eye velocity was assessed using a linear mixed effects model, which is well-suited for data with repeated measures (here, measurements within individual cells and across trials for a given visual-vestibular stimulus) with potential correlations between observations within each cell or stimulus condition (Oberg and Mahoney, 2007). The model contained residual rate, residual CV2, and the interaction term as fixed effects, and full random effects for each cell and stimulus condition:
Eijk ∼ βoRateijk+β1CV2ijk+β2RateijkCV2ijk+b0jkRateijk+b1jkCV2ijk+ b2jkRateijkCV2ijk+ ϵijk
where Eijk is the residual eye velocity in the ith time bin in Purkinje cell j for stimulus condition k, β0 represents the fixed effect of spike rate on eye velocity, β1 is the coefficient for the fixed effect of CV2 on eye velocity, β2 is the coefficient for the fixed effect of the interaction term, b0jk, b1jk, and b2jk are the random effect coefficients for rate, CV2, and their interaction, respectively. Intercept terms were not included because the calculation of residuals removes the intercept. The model was fit using the fitlme function in MATLAB using the default maximum likelihood method. The resulting coefficients and confidence intervals are reported in Supplementary file 1. Significance was determined by computing the log-likelihood ratio between the full model (above) and a reduced model with either the fixed effect of spike rate (βo), the fixed effect of CV2 (β1), or the fixed interaction effect (β2) removed. An alternate full model without the interaction term was also assessed with no change in the conclusion. The outcomes of the log-likelihood test reported in the Results agreed with the outcome of tests for significance of the individual fixed effects parameters in the full model, as assessed by a Wald test comparing the coefficient's estimated value with its estimated standard error.
To visualize the relationship between oculomotor output and spike rate and irregularity, the residuals were graphically summarized in two ways (Figure 2). First, each individual time bin was classified into low or high CV2, according to whether the CV2 residual fell into the lowest or highest third of the distribution for that cell. Data within each group (low or high CV2 bins) were then further binned according to the spike rate residual, and average eye velocity was computed for each bin, first for all data points within each cell, and then averaged across cells. Second, a complementary visualization was created with spike rate rather than CV2 as the categorical variable: each time bin was classified into low or high spike rate, according to whether the rate residual fell into the lowest or highest third of the distribution for that cell. Data were then binned according to their CV2 residual and average eye velocity was computed for each bin, first for each cell, and then averaged across cells.
Optogenetic stimulation in mice
All experimental procedures were approved by the Administrative Panel on Laboratory Animal Care at Stanford University. Experiments were performed on male and female adult (≥8 weeks old) mice. All mice were housed on a reversed 12 hr light/12 hr dark cycle, and experiments were conducted during the dark cycle. ChR2 was selectively expressed in Purkinje cells by crossing Ai32 mice conditionally expressing ChR2(H134R)-EYFP (Madisen et al., 2012; Jackson Laboratory #024109) with mice expressing Cre under the control of the L7 promotor ((Pcp2-cre)3555 Jdhu/J; Jackson Laboratory #010536; Barski et al., 2000; Witter et al., 2016).
A head post was secured to the skull with three screws and dental cement to allow head restraint. Guide cannulas (C312G, Plastics One) were implanted bilaterally to target the flocculus, as previously described (Nguyen-Vu et al., 2013). Eye movements were recorded using magnetic eye tracking (Payne and Raymond, 2017). Briefly, a 0.75 mm x 2 mm (diameter x height) cylindrical neodymium magnet was implanted beneath the conjunctiva of the left eye and secured with VetBond. An angular magnetic field sensor (HMC1512, Honeywell Inc) was attached via dental cement to the head implant and used to detect the angle of the magnet, and thus the angle of the eye as it rotated in its socket. After surgery, mice were individually housed and were allowed to recover for at least 5 d before behavioral experiments.
Optogenetic stimulation of Purkinje cells
Optogenetic stimulus trains were delivered unilaterally to the cerebellar flocculus of awake, head-restrained mice in a dark room, and the resulting eye movements were measured. Optical stimulation was delivered via a 250 µm, 0.66 NA optical fiber (Prismatix). The shaft of the optical fiber was covered with black heat shrink tubing (Vention Medical) and the dental cement head implant was painted black to prevent light leakage. Blue light at 450 nm was provided by a high-powered LED light source (Prismatix, Israel), and the current was adjusted to produce either 1 mW or 10 mW at the tip of the optical fiber. The tip of the optical fiber was acutely inserted through the surgically implanted cannula and gradually advanced using a micromanipulator until eye movement responses to light pulses were first detected.
Optogenetic stimulus trains consisted of brief, 1 ms pulses of light delivered in either regular or irregular temporal patterns. Stimulus trains were 500 ms in duration, with 3 s between the start of one train and the start of the next. For each stimulus train, the CV of the interstimulus intervals was either 0 (perfectly regular), 0.5, or 1. Irregular stimulus trains were generated in MATLAB by using a Gamma distribution to generate sequences of interstimulus intervals. For each stimulus train, interstimulus intervals were drawn randomly from a Gamma distribution with parameters adjusted to generate the target stimulus rate and CV. Interstimulus intervals less than a refractory period of 3 ms were discarded. The resulting stimulus train was checked for three criteria: 1) the total number of stimuli in the irregular train was exactly the same as in the regular train of the same rate; 2) the mean stimulus rate, calculated by taking the reciprocal of the mean interstimulus interval, was within 5% of the target rate; and 3) the CV was within 5% of the target CV of 0, 0.5, or 1. If any of these conditions were violated, the stimulus train was discarded, and a new train was drawn, until 60 different irregular trains were obtained that satisfied the conditions for each stimulus frequency and CV. In addition to the 60 non-repeated irregular trains, for CV = 1 (20, 60, and 100 Hz), one irregular stimulus train was repeated to provide a measure of trial-to-trial variability, and to allow visualization of the average Purkinje cell (Figure 3D,E) and eye movement responses (Figure 4A,B) to irregular trains. Thus, each block of an experiment consisted of 18 different types of stimulus trains: regular stimulus trains (CV = 0) at 20, 40, 60, 80, and 100 Hz, irregular non-repeated trains (CV = 0.5) at 20, 40, 60, 80, and 100 Hz, irregular non-repeated trains (CV = 1) at 20, 40, 60, 80, and 100 Hz, and irregular repeated trains (CV = 1) at 20, 60, and 100 Hz. The order of the stimulus trains was randomized within each block. For the irregular trains, summary statistics (Figure 3F,G; Figure 4C–E) were calculated on the non-repeated trains, for which each trial was a unique temporal stimulus pattern. Mutual information (Figure 5A) was calculated from the regular trains and the repeated irregular trains (20 Hz, 60 Hz, and 100 Hz). The linear temporal filter model (Figure 5B–E) was trained on the non-repeated irregular trains, and tested on the repeated regular and irregular trains.
In vivo recordings from Purkinje cells during optogenetic stimulation
Extracellular electrophysiological recordings were performed to characterize the simple spike responses of Purkinje cells to optogenetic stimulation. A tungsten microelectrode (Microprobes for Life Sciences, MD) was inserted directly alongside an optical fiber, and advanced past the tip of the optical fiber until a Purkinje cell layer was encountered. Signals were digitized in Spike2 at a sample rate of 50,000 Hz and stored offline. Spike sorting was conducted offline using Plexon Offline Sorter (Plexon Inc) to implement template matching in combination with principle component visualization. Spike sorting using the MountainSort algorithm (Chung et al., 2017) yielded similar results (not shown). Any cell that exhibited signs of damage, such as bistable firing, inconsistent spike amplitudes, or a prolonged or abnormal spike waveform, or that was insufficiently isolated, as assessed from the first two principle components, were excluded. Only cells that were well isolated for at least 5 repeats of each stimulus condition were included in the analysis. Recordings were made from a total of 41 neurons, including 15 well-isolated Purkinje cells (13 cells recorded during 1 mW stimulation and 7 cells recorded during 10 mW stimulation, including 5 cells recorded for both light intensities), 12 putative cerebellar interneurons (8 cells during 1 mW stimulation and 4 cells during 10 mW stimulation), and 16 cells that were excluded for insufficient isolation, in a total of six mice.
Measurement of eye movements responses to optogenetic stimulation
Eye movement responses to optogenetic stimulation of Purkinje cells were recorded in 13 mice, including five mice whose eye movements were recorded during the electrophysiological recordings. Eye movements were evoked by unilateral stimulation of the flocculus while the mouse was head-fixed in a dark room. Stimulation experiments were performed on the left and right flocculus on separate days, with at least two days between experiments. Each flocculus was first tested using a higher light intensity (10 mW). An experiment was excluded from the analysis if no evoked eye movements could be detected, or if the initial and steady state eye movement responses to optogenetic stimulus trains were in opposite directions (7/26 flocculi excluded for 10 mW stimulation). The remaining 19 flocculi were tested using a lower light intensity (1 mW), with the same exclusion criteria (3/19 flocculi excluded during 1 mW stimulation). For two mice with multiple repetitions of the experiment on the same flocculus (2 and 3 days, respectively), data were combined across days before averaging.
Eye movements were recorded using a previously published magnetic eye tracking method (Payne and Raymond, 2017). A small magnet was implanted beneath the conjunctiva of one eye as described above, and a skull-mounted magnetic field sensor (Honeywell International, Inc) was used to detect changes in the magnetic field as the magnetic moved with the eye. Eye movement-related signals from the magnetic sensor were recorded in Spike 2 (Cambridge Electronic Design) at a sample rate of 1000 Hz. The magnetic eye tracking system was calibrated by simultaneously recording eye position with a dual-angle video-oculography system during 1–2 min of sinusoidal vestibular stimulation in the light (1 Hz, ±20°/s). Eye position obtained from video-oculography and voltages from the two channels of the magnetic sensor were each differentiated and smoothed with a 100 Hz low pass filter and then fit with sine waves. The channel of the magnetic sensor whose differentiated voltage signal was best fit by a sine wave was selected. A scale factor for this channel was calculated by dividing the amplitude of the sine wave fit for the eye velocity signal recorded using video-oculography by the amplitude of the sine wave fit for the magnetic sensor. After the 1–2 min calibration session, the video-oculography system was removed from the mouse's field of view and experiments were conducted using magnetic eye tracking alone.
Eye position signals were digitally differentiated to yield eye velocity. Saccades and movement artifacts were detected using an automatic velocity threshold, and trials or sinusoidal stimulus cycles with saccades or movement artifacts were excluded from the analysis. For plotting example traces, eye position and velocity data were smoothed with a 5 ms moving average.
Optogenetic stimulation: data analysis
Neural activity and eye movements evoked by optogenetic stimulation were analyzed in MATLAB to obtain the means across trials for each time point within a trial, or averaged across the entire 500 ms stimulus train. Eye velocity data were normalized to the maximum mean velocity for each experiment to allow comparison across experiments.
Mutual information
Mutual information between the Purkinje cell spike rate and eye velocity was calculated for different temporal smoothing windows. For each Purkinje cell recorded during 1 mW optogenetic stimulation, spike counts were binned in 1 ms intervals, and averaged across trials to yield trial-averaged spike rates with 1 ms resolution. The population spike rate was computed by averaging spike rates across Purkinje cells. Mutual information between the population spike rate and eye velocity was calculated separately for the eye velocity responses in each behavioral stimulation experiment, and then averaged across experiments. Mutual information was calculated separately on data from regular stimulus trains (CV = 0; 20, 60, and 100 Hz) and repeated irregular stimulus trains (CV = 1; 20, 60, and 100 Hz).
Because spike rate and eye velocity are continuous variables, rather than discrete variables, the mutual information between spike rate and eye velocity was calculated using a kernel estimate, which allows each individual observation to inform the probability distribution over the width of the kernel (Moon et al., 1995). The kernel estimate was computed using the MATLAB Central File Exchange function kernelmi with a default kernel width determined by the number of data points, N: H=(N+1)/12⋅N1+0.25.
To account for the delay between Purkinje cell activity and eye velocity, a time delay was added to the Purkinje cell activity before calculating mutual information. The calculation of mutual information was repeated with time delays of 0–10 ms, in 1 ms increments, and the delay that maximized the average total mutual information, 6 ms (for the unsmoothed data), was used for all subsequent calculations of mutual information.
To estimate the temporal decoding window, spike rate was smoothed by taking a moving average over progressively longer time windows, from 1 ms (no smoothing) to 20 ms, before calculating mutual information between smoothed spike rate and unsmoothed eye velocity. Similar results were obtained if eye velocity was also smoothed at the same window length (not shown).
Linear temporal filter fits
A linear temporal filter was used to predict eye velocity on rapid timescales from Purkinje cell spike rates. For each experiment, a linear temporal filter, F, was calculated according to the following:
E˙^i[t]=∑m=0MF[m]Pi[t−m]
where E˙^i[t] is the predicted eye velocity at time point t within stimulus train with pattern i, Pi[t] is the Purkinje cell spike rate averaged across the population of recorded cells for stimulus train i, and m is the index over the duration of the filter. For each experiment, the training set for fitting the linear filter consisted of the single-trial eye velocity responses to non-repeated irregular stimulus trains (CV = 1; 20, 40, 60, 80, 100 Hz), excluding the single pattern that was repeated. The filter was calculated using total least squares linear regression, since the uncertainty in both eye velocity and neural activity would bias ordinary least squares linear regression towards small filter weights. The test set consisted of the trial-averaged eye velocity responses to regular (CV = 0; 20, 60, 100 Hz) and irregular (CV = 1; 20, 60, 100 Hz) repeated stimulus trains. For each stimulus train in the test set, eye velocity was predicted by convolving the linear filter with the population mean spike rate using the equation above. The RMSE of the eye velocity prediction from the model was then compared for regular and irregular stimulus trains from a given experiment. The relationship between predicted and actual eye velocity was linear (correlation coefficient 0.777 ± 0.038, n = 16; see example in Figure 5D); therefore a nonlinearity was deemed unnecessary. Likewise, no regularization was necessary.
The linear filters were fit using unsmoothed spike histograms and behavior, both with 1 ms temporal resolution. To compare the model predictions, spike rate and eye velocity in the test set were smoothed with a sliding window of 5 ms, based on the estimated temporal decoding window derived from the mutual information calculations. This smoothing window was chosen to aid visualization and was not critical; similar results were obtained without any smoothing of the test data (1 ms time bins; RMSE 16.9°±1.8° regular, 16.5°±1.7° irregular, p=0.23, n = 16, paired t-test; compare with results in Figure 5E obtained using the 5 ms smoothing window).
Biophysical model
Simulations were performed in the NEURON simulation environment (Hines and Carnevale, 1997) and analyses were conducted in MATLAB. A biophysically realistic model of a Purkinje cell target neuron in the deep cerebellar nuclei was adapted from Luthman et al. (2011). Other than altering the rate and temporal pattern of input spikes, the only parameters we changed in the model are those described in the text: the presence or absence of short-term depression, and the strength of excitatory and inhibitory conductances. The model target neuron received inhibitory synaptic input from 50 Purkinje cells (Person and Raman, 2012a) through a total of 450 inhibitory synapses (nine synapses per Purkinje cell) and excitatory synaptic input from 150 mossy fibers. The 50 Purkinje cells each fired spontaneously at a rate of 60 sp/s (to approximately match the mean spontaneous firing rate of 62 sp/s in the population of Purkinje cells recorded during optogenetic stimulation), with a CV of 0.5 for the ISIs between spontaneous spikes (to approximately match the irregularity of spontaneous firing recorded in vivo; Figure 1E). The mossy fibers each fired spontaneously at a mean rate of 20 sp/s with a CV of 1. Spontaneous activity on each trial was generated by drawing a sequence of ISIs from a Gamma distribution, removing spikes within a refractory period, and accepting only ISI sequences meeting the following criteria: (1) the total number of spikes was equal to the target value defined by 60 sp/s for Purkinje cells, or 20 sp/s for mossy fibers, (2) the mean spike rate, calculated by taking the reciprocal of the mean ISI, was within 10% of the target rate of 60 sp/s (Purkinje cells) or 20 sp/s (mossy fibers), and (3) the actual CV was within 10% of the target value of 0.5 (Purkinje cells) or 1 (mossy fiber). The target neuron contained eight Hodgkin-Huxley style ion channel conductances: a fast sodium current, a persistent sodium current, mixed fast Kv3 and slow Kv2 delayed rectifying current, a high-voltage-activated calcium current, a low-voltage-activated calcium current, a calcium-gated potassium (Sk) current, a hyperpolarization-activated cyclic-nucleotide gated (HCN) current, and a tonic non-specific cation current promoting spontaneous spiking.
To simulate optogenetic stimulation, 'stimulus-driven' spikes were added to the spontaneous spikes in each model Purkinje cell. Stimulus trains identical to those used in vivo triggered a spike in each model Purkinje cell at a variable latency described by a Gaussian distribution with mean 1.24 ms and standard deviation 1.36 ms (truncated at 0 ms) mimicking the latency jitter observed in vivo (Figure 3B,C). Optogenetic stimulus-driven spikes were not allowed to occur within an absolute refractory period of 1 ms after a spontaneous spike, in accordance with the short ISIs observed during optogenetic stimulation in vivo, whereas spontaneous spikes were restricted by an absolute refractory period of 3 ms after any other spike. For the small number of cases where a stimulus-driven spike was supposed to occur within the refractory period, that spike was skipped and spiking resumed with the next spontaneous or stimulus-driven spike scheduled to occur outside the refractory period. Since the optogenetic stimulation (0–100 Hz) was added on top of spontaneous activity (60 sp/s), the total spike rate of the model Purkinje cells ranged from 60 sp/s to 160 sp/s. A minimum of 10 trials were run for each rate, irregularity, and parameter set.
Model parameters describing the strength of excitation and inhibition were systematically varied: the excitatory conductance (gE) was scaled from 0.5 to 2 times the original values of 200 pS for AMPA and 172 pS for NMDA peak conductance (fast + slow), and the baseline inhibitory conductance (gI0) was varied from 0.5 to 1.5 times the original value of 1.6 nS (Steuber et al., 2011). The models were run either with short-term synaptic depression at the synapses from Purkinje cells to the target neuron (Luthman et al., 2011; Shin et al., 2007), or with no short-term depression. The inhibitory conductance in the model without short-term depression was adjusted to equal the steady state conductance at the maximum spike rate in the corresponding model with short-term depression.
To test the effects of irregularity during asynchronous Purkinje cell spiking, asynchronous model Purkinje cell activity was generated by driving each individual Purkinje cell with the same stimulus train as during the corresponding synchronous optogenetic simulation, but with the stimulus-driven spike train for each cell independently shifted circularly by a random delay between 0 and 500 ms (Figure 8).
Random walk model
The random walk simulations (Figure 9) were conducted using an extremely simple model neuron that perfectly integrates its inputs. On each time step, the membrane potential of the model neuron changes by an amount drawn from the random variable ~𝒩μ,σ, which represents the mean (μ) and standard deviation (σ) of the net contribution of all excitatory and inhibitory synaptic and intrinsic conductances (arbitrary units). The analytic approximations for the random walk model with μ ≥ 0 are taken from Salinas and Sejnowski (2000):
rout2Δt2 Vthresh+σ2-Vreset2-routΔt2μVreset+σ2-μ2=0
where rout is the output rate, Δt is the time step, Vthresh is the threshold 'voltage' (in arbitrary units), Vreset is the reset voltage, and μ and σ are given above. Vmin, the minimum voltage permitted during the random walk, is not explicit in the equation above but is assumed to be 0, and can be effectively lowered by increasing both Vthresh and Vreset in parallel. Parameters were chosen to either match the previously published simulations (Salinas and Sejnowski, 2000; Figure 9); black: Δt = 1 ms, Vthresh = 40, Vreset = 20, Vmin = 0, μ = 1.5, σ varied) or changed to either increase the E/I ratio (μ = 2.5, red), decrease the E/I ratio (μ = 0, blue), or eliminate the reflecting floor (Vmin = –inf, cyan).
Statistical tests were conducted using MATLAB and GraphPad Prism. All tests were two-tailed, and the significance level was set at p<0.05. Data are summarized as mean ± SEM. The D'Agostino-Pearson omnibus test (Prism) was used to assess normality of the data for ANOVAs and t-tests. Data were normally distributed in the recordings of the Purkinje cell response to optogenetic stimulation (Figure 3), with the exception of one extreme outlier. The outlier was detected using both the modified z-score of Iglewicz and Hoaglin (1993) (z-score averaged across conditions at 100 Hz stimulation: 10.3, recommended threshold: 3.5) and Grubbs' extreme studentize deviate test (Grubbs, 1969; t11 = 8.9, p=10−6). Because parametric statistics such as means are highly sensitive to such outliers, all statistics were repeated both with and without the outlier, and the outlier was not included in the summary figures provided in the main text.
Two-way repeated measures ANOVA were conducted in Prism to assess the impact of optogenetic stimulus rate and irregularity (independent variables) on Purkinje cell spike rate and irregularity (Figure 3G). If the interaction term was significant, post-hoc comparisons were performed using the Tukey correction for multiple comparisons. A linear mixed effects model was conducted in MATLAB to assess the relationship between either Purkinje cell spike rate or stimulus rate and irregularity on eye velocity, since slightly different Purkinje cell spike rates were evoked by regular v. irregular stimulation at each frequency (Figure 4). The linear mixed effects model predicted eye velocity from fixed effects of Purkinje cell rate or stimulus rate, stimulus irregularity condition, and their interaction, with random intercepts by subject. Statistical significance was assessed using a likelihood ratio test with either stimulus irregularity condition removed or the interaction term removed. Paired t-tests were conducted in MATLAB to compare RMSE of the linear temporal filter predictions for the regular and irregular trains (Figure 5).
A linear mixed effects model was implemented in MATLAB for analyzing the correlation between Purkinje cell spike rate, CV2, and eye velocity, and statistical significance was assessed using a likelihood ratio test (see above). The residual data were not normally distributed, however, comparisons of means using linear models are robust to deviations of normality when the sample size is sufficiently large (Lumley et al., 2002; Gelman and Hill, 2007).
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Richard B Ivry
Senior and Reviewing Editor; University of California, Berkeley, United States
David J Herzfeld
Reviewer; Johns Hopkins University, United States
Thank you for submitting your article "Cerebellar Purkinje cells control movement with a rapid rate code that is invariant to spike regularity" for consideration by eLife. Your article has been reviewed by three peer reviewers, and the evaluation has been overseen by Rich Ivry as the Senior Editor. The following individual involved in review of your submission has agreed to reveal his identity: David J Herzfeld (Reviewer #1).
This manuscript addresses the question of how the regularity or irregularity of Purkinje cell firing contributes to motor behavior through a systematic analysis of the properties of floccular Purkinje cell firing rates during eye movements in primates and mice, including optogenetic (synchronous) stimulation of Purkinje cells with manipulations of regularity. The results provide evidence that regularity is not a primary variable in controlling oculomotor output.
All the reviewers were favorable about the caliber of the experiments and the extent of data gathered.
1) The most fundamental criticism that was agreed upon in an extensive discussion was that the dichotomizing of ideas like regularity/irregularity, rate/time, synchronous/asynchronous set up somewhat arbitrary oppositions that may not always be meaningful. For instance, it is not clear that it makes sense to refer to rate codes on the time scale of <2 spikes (please see reviewers' comments below), and consequently some of the interpretations and conclusions are overstated. To quote from the reviewers' discussion, "As written, it is possible to come away with the conclusion that all of this temporal coding business is refuted and we should just think about a rate code. The issue that the 'temporal code' can only be interrogated experimentally if we have access to coordinated patterns of PCs converging onto a [target] cell seems like an important one for the authors to address." More precise definitions and resulting interpretations would make the content more accurate as well as more accessible, and would help readers avoid conflating ideas (e.g., regularity / temporal coding / synchrony) that are distinct.
2) There was also a strong consensus that the efforts to overturn the pathological irregularity hypothesis were distracting from the main focus of the paper, since the results do not actually address pathologies and thus the link is somewhat weak. Although it is reasonable to cite the work on pathology as a motivation for the study, the reviewers generally agreed that emphasizing the positive outcomes of the study in the context of non-disease states would greatly improve the manuscript.
Another quote from the discussion expressed these points well and is excerpted and slightly paraphrased here for conciseness: "What the pathological papers show is that the average PC firing over many trials seems normal in animal models while the firing of single PCs during single trials is very irregular ('noisy'); this noise could potentially not average out over the whole population converging on a CN neuron and yield improper output. [This study] suggests that the time scale where the 'averaging out' should take place is in the sub-5ms range (at least in the absence of mf inputs). [With] the current state of literature (including this manuscript), it seems possible that the population instantaneous rate has to be coordinated/ specified/ learned at the 3-4ms time scale." The issues raised were that disproving the "pathological irregularity" hypothesis would require showing that the same eye velocity is obtained with regular and irregular spike trains. Figure 4 seems to show instead that while average results are similar, single trials indicate that temporal structure (rather than average rate) matters to the specific movements.
Reviewer #1:
- In the analyses surrounding Figure 2A-B (and Figure 2—figure supplement 1), please statistically state that the residuals of rate and CV2 are not correlated for both mice and monkeys. Given the results in Figure 2B, you should be able to perform a similar analysis to Figure 1B (significant correlation between the residual eye velocity and residual firing rate timeseries) without the need to separate the CV2 residuals into "low" and "high" bins. You could then statistically test the actual timeseries relationship by computing the coefficients of a multiple linear regression model with an output of eye velocity and show no significant effect of CV2. Such an analysis should have more power than the current segregation method.
- In Figure 5, it would be nice to see the kernel fit to 60Hz regular stimulation as well (overlayed on the current "irregularly fit" kernel). These two kernels should be visually the same.
- The linear filter in Figure 5B systematically underestimates the steady-state amplitude of the velocity response to regular stimulation (and to some extent, irregular stimulation) at high frequencies (Figure 5C, 100Hz). To me, this would seem to suggest that some low-pass filtering must be occurring downstream of the Purkinje cells. I would be interested to see the optimal linear filters fit to the 20Hz, 60Hz and 100Hz regular firing data. I imagine that the kernels would look different at the various frequencies – potentially suggesting that spike timing still matters, but only for relatively short ISIs (i.e., the net eye position after 250ms stimulation at 150Hz followed by 250ms stimulation at 50Hz may look different than position after a 500ms stimulation at 100Hz).
- I think that the authors should be very careful about wading too far into a debate on rate versus temporal codes. In particular, I find that the phrase "rapid rate code" goes slightly too far in the current manuscript. It is clear from Figure 4 and the temporal filter in Figure 5 that a single optical pulse (or, synonymously, spike) has a clear effect on motor output largely independent of spike timing. A single spike, in my mind, cannot have a rate – rate is defined either relative to the previous spike (ISI) or as the average within a time bin. I would advise the authors to focus the prose on "regularity" when discussing the contributions of single spikes rather than "rapid rates".
In its state, the manuscript sounds over-confident in disproving a role of (poorly defined) increased irregularity of discharge in motor dysfunction. Negative results are tricky to establish, and a combination of a) study of natural irregularity (which may not recapitulate at all the pathological irregularity), b) massive optogenetic stimulations (providing very artificial over-synchronous patterns of firing), c) numerical models, falls a bit short of a final proof. While this manuscript brings a lot of very interesting experimental and modeling work, I feel it would be greatly improved by playing down the debate over regularity to the benefit of other interesting results (fluctuation of CV2 during a task in normal animals, tight temporal coupling of (synchronized) PC and eye movements, STP in the floccular output, etc.), rather than extrapolate to pathological conditions which are in fact barely studied in the study.
My main concerns are the following:
1) Irregularity is not really defined, and the debate not clearly phrased: Purkinje cells in normal brain in vivo are certainly not perfectly rhythmic, so we can already state that good cerebellar function is achieved with somewhat irregular Purkinje cell discharge (a position certainly agreed by most proponents of the pathological irregularity stand). Irregularity in the manuscript seems to refer only to high values of the (simple and imperfect) measures of the CV or the CV2 of the interspike intervals, which are respectively more relevant to stationary or non-stationary cases. These values are often reported for PC recordings (normal and pathological conditions) but they provide limited insight into the temporal structure of the spike trains and into the distribution of ISI: e.g. very high CV2 may be obtained for a cell producing very regular high-frequency doublets of spikes (signal perfectly periodic with only 2 possible ISIs); conversely, a very skewed distribution of ISI may be associated with very small CV2 if the successive ISIs are ordered (progressively accelerating/decelerating neuron). Whether the surrogate irregular patterns used in the study are "pathological" is not justified; they may indeed barely recapitulate the actual disrupted firing patterns observed in motor disorders and thus strongly limits the relevance of this study to test whether these patterns cause motor dysfunction. This is particularly critical for the modeling of asynchronous Purkinje cells (which is indeed the only part of the manuscript which could estimate the pathological contribution of irregular discharge). Finally, for evident reason of synaptic summation, synchronous and asynchronous irregularity in presynaptic neurons are going to affect very differently the target neurons; the manuscript is moving between single cell (optokinetic data)/synchronous (optogenetic and model)/asynchronous (model only) situations and barely acknowledges (they are identically named) their profound heterogeneity (nor discuss their differential relevance to pathological conditions). For example, sentence in the fourth paragraph of the subsection "No evidence for an influence of Purkinje cell spike regularity on motor control",implicitly extends results from synchronous irregularity to any form of irregularity.
2) The first part of the manuscript studies whether the natural irregularity of PC is correlated with variability in movements. The main difficulty to interpret these data is for the negative result (residual CV2 not correlated with residual eye movements). Indeed, when the rate of a single Purkinje cell correlates with movement, this may either reflect the contribution of that single PC (in which case one can interpret the lack of contribution of fluctuation of the regularity of this cell), or that it reflects a global shift of excitation of the population of PC controlling the movement (and it may not matter that a single PC is a bit more irregular; I suspect that the model would confirm that). The Discussion acknowledges this issue but concludes from optogenetic data (synchronous PC stimulation) that this is not the case; however, optogenetically-driven synchrony deeply affects the impact of PC firing onto the cerebellar nuclei (Sarnaik and Raman, 2018). It is therefore not possible to conclude that the lack of correlation between residual CV2 and residual movements results is not due to the fact that these residual CV2 fluctuations are not correlated at the level of the population.
Related points:
a) The irregularity (as measured by the CV2) is naturally strongly anti-correlated with the average firing rate of neurons with a refractory period. This can be easily verified with Poisson trains trimmed from the short (<3ms) ISIs that the CV2 drops from ~0.9 for 20Hz train to ~0.5 for 150Hz cell. The manuscript states (subsection "Mean spike rate and regularity both vary with oculomotor behavior") that the variability observed is not due to this simple effect but does not provide the demonstration (so the changes of CV2 may simply reflect the leftward shift of the ISI distribution shape -with a fixed refractory period- along the task, and the residual would be just stochastic fluctuations).
b) Please assess statistically the independence of the residuals of CV2 and residuals of rate (Figure 2—figure supplement 1).
c) Given the link between them, a mixed effect model with the interaction term between CV2 and rate would have been useful
3) The second part of the paper studies the coupling of PC firing to eye movement in a well-controlled, but very artificial configuration: no ongoing movement (and thus likely very little mossy fiber activity in the cerebellar nuclei), over-synchronous likely non physiological PC firing (very brief and efficient stimulations). Overall the results presented demonstrate very nicely that in these conditions, eye movements may follow very tightly arbitrary patterns of synchronous PC and they even provide accurate quantification on time scales of this drive. However, since the debate on PC regularity does not at all assumes synchronized PC firing patterns, this brings little in the debate. These data however provide a strong and original assessment of the PC-movement coupling capacities. The relevance to physiological conditions should be discussed, or better, explored in the context of a task (perturbation of movements), where more physiological mossy fiber activity would be present and using lighter stimulations.
4) The meaning of the Iirreg index is a bit difficult to connect with movement control. Since the link between target neuron and eye movement has been modeled, why not directly assess the error (or variance) of eye velocity as a function of irregularity?
5) The notion of "rate code" is a little unclear when it operates at the time scale of the code shorter than the ISIs (= the time to define an instantaneous firing rate)! This sounds more like a fast population code.
No major comments for revision.
We could not agree more with the reviewers that precise definition and use of terminology is critical, and have revised the text to clarify definitions with more extended discussion of potential points of confusion regarding terminology:
We now include an explicit acknowledgement that regularity/irregularity lie on a continuum (Introduction, third paragraph). In addition, we have taken care to soften the dichotomy between regular/irregular and synchronous/asynchronous by using phrases like "more irregular" and "less synchronous" throughout the manuscript.
We have expanded our discussion of the terms 'rate coding' and 'temporal coding'. Throughout the manuscript (Introduction, Results, and Discussion), we indicate that we have adopted the definition of temporal coding used by Theunissen and Miller, 1995, with temporal coding used to refer to the precise temporal pattern of spikes encoding information beyond that carried by changes in spike rate over behaviorally relevant timescales. We also explicitly state (Introduction, second paragraph, subsection "No evidence for additional influence of spike irregularity", first paragraph) that temporal coding could potentially take many forms, and we focused on just one form, the irregularity of the interspike intervals, since previous work in the cerebellar field has suggested that the irregularity of spiking in individual Purkinje cells might play a major role in their control of downstream neurons and behavior, in addition to, or instead of, the rate of spiking in the Purkinje cells (reviewed in De Zeeuw et al., 2011).
We agree with the reviewers that on very short time scales (e.g., < 5 ms), the distinction between rate coding and temporal coding is less intuitive, and we are grateful to the reviewers for highlighting the need for more extended discussion of this issue, which we now include in the subsection "Rapid rate coding". At the level of individual neurons, it may not make sense to talk about rate coding on a time scale shorter than the interspike interval, since one needs at least two spikes to compute a rate. However, we think it is perfectly reasonable to consider the rate code in a population of neurons on such rapid time scales, since the population of ~50 Purkinje cells converging on a given target neuron will collectively emit more than two spikes, on average, over time scales shorter than the ISI in an individual Purkinje cell (e.g., 5 ms). In the revised manuscript (subsection "Rapid rate code for eye movements"), we clarify that in our stimulation experiments, we are always manipulating the rate and irregularity of spiking in a large population of Purkinje neurons. A key, take home message of the manuscript is that over both short and long time scales (a few milliseconds to 500 milliseconds) consideration of the population spike rate alone is sufficient to account for the eye velocity observed across our experimental conditions, with no need to hypothesize an additional, distinct effect of spike irregularity.
We have added a new, summary figure to provide a visual summary of these ideas (Figure 10).
We think our manuscript provides a useful contribution to the discussion in the scientific literature about the effects of Purkinje cell spike irregularity by offering an alternative, or at least more nuanced, perspective on this issue.
We agree that "all of this temporal coding business" is not refuted by our findings, and explicitly acknowledge (subsection "No evidence for additional influence of spike irregularity", subsection "Potential for different coding strategies in different regions of the cerebellum") that there could be 1) other forms of temporal coding in the Purkinje cells, and/or 2) conditions where the irregularity of Purkinje cell spiking could have an influence on downstream neurons above and beyond the effects on spike rate. Indeed, we report in the manuscript (subsection "Biophysical model of Purkinje cell synaptic transmission", eighth paragraph) that our modeling work identified a key parameter, namely the relative strength of Purkinje cell inhibition versus excitatory input to the target neurons, that could determine whether Purkinje cell irregularity has an additional effect on the target neuron beyond the effects of spike rate. In the revised manuscript, we include additional, new simulations(Figure 9, subsection "Random walk model of the effect of input variance on target neuron spiking") showing that even in an extremely simple, random-walk simulation, the moment-by-moment variability of the total synaptic input converging on a target neuron sometimes affects the mean rate of target neuron output, and sometimes does not, depending on the parameters of the model. We acknowledge (subsection "Potential for different coding strategies in different regions of the cerebellum") that certain parts of the cerebellum could operate in a region of parameter space where Purkinje cell irregularity affects the mean rate of their target neurons. Further, we include an alternate mechanism by which the level of spike irregularity can affect motor readout without needing to invoke a temporal code, by altering the reliability of the population-level spike rate code (new Figure 6). Thus, our results do not refute previous work on spike irregularity of the Purkinje cells, but rather highlight the need for more extensive study of the conditions under which spike irregularity contributes or does not contribute to the cerebellar control of behavior.
That said, our results offer an important counterpoint to previous conclusions that spike irregularity is a key component of the code used by Purkinje cells to transmit signals to downstream neurons (Hoebeek et al., 2005; Luthman et al., 2011; De Zeeuw et al., 2011). In contrast to this view, we show that our results on the control of eye movements by Purkinje cells in the cerebellar flocculus can be fully accounted for by the population spike rate. We would note that initially, we expected to find an effect of Purkinje cell spike irregularity, based on the seminal work on this topic in the cerebellar literature (Hoebeek et al., 2005; Walter et al., 2006; Shin et al., 2007; Luthman et al., 2011; Sarnaik and Raman, 2018) and we designed our experiments and looked hard to find such effects. However, despite our initial expectation, we could find no evidence for an effect of irregularity per se, beyond what could be accounted for by the population spike rate. Hence we were persuaded by our data (changed our minds, based on the experimental evidence) that the irregularity of spiking in individual Purkinje cells is not a significant component of the code used by the cerebellar flocculus to control normal eye movements, and that a remarkably rapid rate code can account for our experimental results. We have modified the text to clarify this specific conclusion about the floccular control of eye movements.
Our study highlights the importance of future work to determine the extent to which spike rate and irregularity each contribute to the control of other behaviors by Purkinje cells in other regions of the cerebellum(subsection "Potential for different coding strategies in different regions of the cerebellum").Just as our findings about rate coding for the control of eye movements by floccular Purkinje cells do not necessarily refute previous claims about the contribution of irregularity in other cerebellar regions and other behaviors, our results indicate that caution is likewise merited in generalizing previous findings about spike irregularity. Moreover, our results highlight the importance of adequately controlling for spike rate when considering the effects of spike irregularity in the interpretation of previous and future experiments. By offering an alternative scientific view, we hope that our study will prompt additional, in-depth study of this central issue about the neural code used by the cerebellum.
We also agree with the reviewers that the interrogation of temporal vs. rate coding requires consideration of three key parameters (Figure 10): 1) the timing of individual spikes within the spike trains of individual neurons; 2) the firing rate in an individual neuron or the population, averaged over a behaviorally relevant time window; and 3) the level of synchrony across the population of neurons that converge onto a given target cell. Since current methods do not allow precise experimental control of all three parameters simultaneously, we have combined recording, stimulation, and modeling approaches to interrogate the distinct contributions of firing rate, irregularity, and synchrony. The manuscript discusses the complementary strengths and limitations of our recording, stimulation, and modeling approaches in supporting our specific conclusion about the role of spiking rate vs. irregularity in the control of eye movements.
As pointed out by the reviewers, our main focus was to test the role of spike irregularity in normal motor control, rather than under pathological conditions of disease models. As suggested by the reviewers, the revised manuscript emphasizes the positive outcome of the study: that the normal control of eye movements can be accounted for by a rapid rate code (Introduction, last paragraph, subsection "Random walk model of the effect of input variance on target neuron spiking", last paragraph, Discussion, first paragraph).
We also acknowledge that the range of irregularity we tested in our stimulation experiments was designed to match the range observed in normal mice during oculomotor behavior, as measured in our recording experiments, and that our most irregular stimulation condition produced a mean CV of the interspike interval (0.82) that was less irregular than typically observed under pathological conditions (where CVs of 0.77 – 2.25 have been reported; Hoebeek et al., 2005; Gao et al., 2012; Stahl and Thumser, 2014; Mark et al., 2015; subsection "Rapid rate code for eye movements", last paragraph).
Another quote from the discussion expressed these points well and is excerpted and slightly paraphrased here for conciseness: "What the pathological papers show is that the average PC firing over many trials seems normal in animal models while the firing of single PCs during single trials is very irregular ('noisy'); this noise could potentially not average out over the whole population converging on a CN neuron and yield improper output. [This study] suggests that the time scale where the 'averaging out' should take place is in the sub-5ms range (at least in the absence of mf inputs). [With] the current state of literature (including this manuscript), it seems possible that the population instantaneous rate has to be coordinated/ specified/ learned at the 3-4ms time scale."
Although our focus is on normal cerebellar physiology, the reviewers' comments motivated us to conduct additional simulations to more rigorously test the potential connection between our findings in normal mice and previous findings of abnormal spike irregularity of Purkinje cells under the pathological conditions of disease models. These simulations support the idea that abnormally high levels of Purkinje irregularity observed under pathological conditions could potentially disrupt the normal control of behavior by degrading the precision of the rate code on the rapid time scales (of 3-5 ms), which our analysis suggests is the time scale at which the rate code is read out downstream (Figure 6; subsection "Rapid rate code for eye movements", last paragraph). In the original manuscript, we had included this as a speculative Discussion point. The more formal quantification of this idea improves the manuscript by 1) providing an alternative explanation for the disrupted motor coordination associated with abnormally irregular Purkinje cell spiking (which can be tested against the explanation that pathological irregularity has an effect independent of the degraded precision of the rate code); and 2) providing a stronger connection between the effects of irregularity under normal and pathological conditions. We greatly appreciate the reviewers' comments, which motivated us to conduct the additional simulations.
The issues raised were that disproving the "pathological irregularity" hypothesis would require showing that the same eye velocity is obtained with regular and irregular spike trains. Figure 4 seems to show instead that while average results are similar, single trials indicate that temporal structure (rather than average rate) matters to the specific movements.
We have revised the text describing the stimulation results illustrated in Figure 4 and Figure 5, to prevent misinterpretation of those results. The central finding from those experiments is that the mean spike rate in a given time interval – either a few milliseconds or the entire 500 ms train – can predict the mean eye velocity in that same time interval, and we could detect no additional effect of irregularity within that interval.
Over short time scales of a few milliseconds, the "temporal structure", or trajectory, of the eye velocity was different for optogenetic stimulus trains with different levels of stimulus irregularity, however, each trajectory could be well accounted for by the temporal structure of the instantaneous firing rate during the train. Therefore, it would be a misinterpretation of Figure 4 to conclude that the "temporal structure (rather than average rate) matters to the specific movements", because the eye velocity in each period of a few milliseconds is well explained by the temporal structure of the average firing rate over those few milliseconds (Figure 5). We have revised the relevant part of the Results section to make this important and potentially confusing point as clear as possible, in a couple of different ways.
Over the longer time scale of 500 ms, we found that stimulus trains with different levels of irregularity evoked the same eye velocity averaged across the train duration when controlling for spike rate. This was a fairly surprising result, since previous work (Luthman et al., 2011) would have predicted different mean eye velocities.
We have created a new figure to visually summarize our experimental and modeling results on the effects of spike irregularity, synchrony, and rate, on short (3-5 ms) and long (500 ms) time scales (Figure 10). This new, summary figure makes two central points:
1) On short time scales of 3-5 ms, both synchrony and irregularity impact the moment-by-moment population spike rate. As illustrated in Figure 10, greater synchrony and greater irregularity can each produce more moment-to-moment variations in the population spike rate. Therefore, our finding of a very fast readout of the population rate (i.e., that the behavior follows the Purkinje cell population rate with a resolution of 3-5 ms) suggests that Purkinje cell synchrony and irregularity could each influence movement via an alteration of the instantaneous spike rate being transmitted by the population. In other words, rapid rate coding is a candidate mechanism for Purkinje cell synchrony or irregularity to influence the target neurons and behavior, with no need to hypothesize an additional effect of synchrony or irregularity, beyond their alteration of population spike rate. Thus, our analysis of rapid rate coding provides a potential unification of disparate phenomena.
2) Over longer time scales of tens or hundreds of milliseconds, the predicted impact of irregularity and synchrony on the meantarget neuron activity (averaged over tens-hundreds of milliseconds) depends on biophysical parameters such as the excitation/inhibition ratio. For a given mean Purkinje cell rate, Purkinje cell irregularity and synchrony may or may not have an additional, independent influence on the mean level of target neuron activity. Moreover, these two regimes are both found within physiologically realistic variations in synaptic parameters (Figure 7, Figure 8, Figure 9).
In the analyses surrounding Figure 2A-B (and Figure 2—figure supplement 1), please statistically state that the residuals of rate and CV2 are not correlated for both mice and monkeys.
A quantification of the correlation between residual rate and residual CV2 was added (Figure 2—figure supplement 1). The correlation is non-zero but sufficiently small (correlation coefficients of -0.24 and -0.29 for monkeys and mice, corresponding to r2 of 0.06 and 0.08, respectively) to allow the linear mixed effects model to distinguish their relationship to eye velocity (Tabachnick and Fidell, 2013).
Given the results in Figure 2B, you should be able to perform a similar analysis to Figure 1B (significant correlation between the residual eye velocity and residual firing rate timeseries) without the need to separate the CV2 residuals into "low" and "high" bins. You could then statistically test the actual timeseries relationship by computing the coefficients of a multiple linear regression model with an output of eye velocity and show no significant effect of CV2. Such an analysis should have more power than the current segregation method.
The separation of residuals into discrete "low" and "high" CV2 or rate bins (Figure 2) was done purely for the purpose of providing an intuitive visualization of the results. The relationship between rate, CV2, and eye velocity residuals was statistically assessed using a linear mixed effects model (subsection "Spike rate, but not irregularity, predicts moment-to-moment variations in eye velocity", first paragraph, Materials and methods subsection "Moment-to-moment analysis of neural activity in monkeys and mice during oculomotor behavior"). The linear mixed effect model has the advantage over multiple linear regression that it can account for correlated random effects attributable to individuals or behavioral conditions. Apparently, the statistical analysis was not given sufficient prominence in the original text, causing the reviewers to overlook it, hence we have revised the text (subsection "Spike rate, but not irregularity, predicts moment-to-moment variations in eye velocity", first paragraph) and Figure 2 legend to better highlight the statistical analysis and to emphasize that it was done without binning the data into the "low" and "high" rate and CV2 bins used for the visualization.
We calculated a kernel fit to the regular stimulation data, and confirmed the reviewer's expectation that the two kernels are visually similar (Figure 5—figure supplement 1). Note that the kernels were fit to the results for stimulation at all frequencies tested (20, 40, 60, 80, 100 Hz), not just 60 Hz.
If this is an essential point, we would appreciate clarification. We do not understand what is to be gained by fitting filters to individual frequencies, and we are concerned about the potential for overfitting if only a single regular frequency is used for the fit, which was part of the rationale for using data from irregular stimulation to fit the model.
The concepts of rate vs. temporal coding have been defined more concretely in the revised text (subsection "No evidence for additional influence of spike irregularity", first paragraph). In addition, in the second paragraph of the subsection "Rapid rate code for eye movements" and subsection "Rapid rate coding", we clarify that our discussion of a "rapid rate code" refers to a population of Purkinje cells. A single optical pulse does not induce a single spike in a single Purkinje cell, but instead produces a brief, strong increase in the probability of spiking across the population of activated neurons. We estimated the population spike rate by binning spikes in short time bins across trials and across sequentially recorded neurons, and found that this estimated population firing rate could predict eye velocity on a time scale of a few milliseconds (Figure 5), without an additional influence of spike irregularity—we can think of no better way of expressing this than "rapid rate code".
We have revised the Introduction and Discussion to clarify that our results are most relevant to understanding the contribution (or lack thereof) of Purkinje cell spike irregularity to normal sensorimotor processing in the normal cerebellum, rather than motor dysfunction in pathological conditions. As described above, we think it is valuable to explicitly consider potential connections between findings made in different contexts, hence we have added additional simulations to begin to bridge our study of spike irregularity in wild type mice with previous observations in mouse models of ataxia.
The reality of systems neuroscience is that "final proof" is rarely if ever possible; the best one can do is to provide convergent evidence from multiple approaches with complementary strengths and limitations. We designed our recording, stimulation, and modeling approaches with this in mind, and have revised the text of the Discussion to more effectively highlight how the strengths of each approach help to address the limitations of the others (subsection "Potential for different coding strategies in different regions of the cerebellum").
1) Irregularity is not really defined, and the debate not clearly phrased: Purkinje cells in normal brain in vivo are certainly not perfectly rhythmic, so we can already state that good cerebellar function is achieved with somewhat irregular Purkinje cell discharge (a position certainly agreed by most proponents of the pathological irregularity stand).
In the revised manuscript, we make the explicit point that there is no perfect spike regularity, even in normal Purkinje cells, only varying levels of irregularity (Introduction, third paragraph). Also, we now describe Purkinje cell spiking as less/more irregular, rather than writing in false dichotomous terms. However, in describing the stimulus trains, which we controlled, the terms regular stimulation and irregular stimulation seem appropriate and well defined, hence we continue to use them in that context.
Irregularity in the manuscript seems to refer only to high values of the (simple and imperfect) measures of the CV or the CV2 of the interspike intervals, which are respectively more relevant to stationary or non-stationary cases. These values are often reported for PC recordings (normal and pathological conditions) but they provide limited insight into the temporal structure of the spike trains and into the distribution of ISI: e.g. very high CV2 may be obtained for a cell producing very regular high-frequency doublets of spikes (signal perfectly periodic with only 2 possible ISIs); conversely, a very skewed distribution of ISI may be associated with very small CV2 if the successive ISIs are ordered (progressively accelerating/decelerating neuron).
To clarify the nature of the Purkinje cell spike trains driven by the stimuli, we now show sample ISI distributions (Figure 3E) in addition to the summary statistics.
Whether the surrogate irregular patterns used in the study are "pathological" is not justified; they may indeed barely recapitulate the actual disrupted firing patterns observed in motor disorders and thus strongly limits the relevance of this study to test whether these patterns cause motor dysfunction. This is particularly critical for the modeling of asynchronous Purkinje cells (which is indeed the only part of the manuscript which could estimate the pathological contribution of irregular discharge).
We agree that our study was not about pathology, and now make it clear that we focused on a range of irregularity that is relevant for normal sensorimotor signal processing in wild-type animals. As we acknowledged in the original manuscript, this range is considerably more regular than reported for the tottering mice modeled by Luthman et al., 2011. In our revised manuscript, we provide a more extensive comparison of the range of irregularity reported in a variety of ataxic (pathological) mouse lines with the range of irregularity we studied (subsection "Rapid rate code for eye movements", last paragraph and subsection "Rapid rate coding can endow sensitivity to spike irregularity and synchrony").
Finally, for evident reason of synaptic summation, synchronous and asynchronous irregularity in presynaptic neurons are going to affect very differently the target neurons; the manuscript is moving between single cell (optokinetic data)/synchronous (optogenetic and model)/asynchronous (model only) situations and barely acknowledges (they are identically named) their profound heterogeneity (nor discuss their differential relevance to pathological conditions). For example, the sentence in the fourth paragraph of the subsection "No evidence for an influence of Purkinje cell spike regularity on motor control", implicitly extends results from synchronous irregularity to any form of irregularity.
We agree with the reviewer that the single cell recordings, the highly synchronous optogenetic stimulation, and the synchronous and asynchronous models differ in important ways, and have revised the text to clarify these distinctions, and the complementary advantages/limitations of each approach (Discussion).
2) The first part of the manuscript studies whether the natural irregularity of PC is correlated with variability in movements. The main difficulty to interpret these data is for the negative result (residual CV2 not correlated with residual eye movements). Indeed, when the rate of a single Purkinje cell correlates with movement, this may either reflect the contribution of that single PC (in which case one can interpret the lack of contribution of fluctuation of the regularity of this cell), or that it reflects a global shift of excitation of the population of PC controlling the movement (and it may not matter that a single PC is a bit more irregular; I suspect that the model would confirm that). The Discussion acknowledges this issue, but concludes from optogenetic data (synchronous PC stimulation) that this is not the case; however, optogenetically-driven synchrony deeply affects the impact of PC firing onto the cerebellar nuclei (Sarnaik and Raman, 2018). It is therefore not possible to conclude that the lack of correlation between residual CV2 and residual movements results is not due to the fact that these residual CV2 fluctuations are not correlated at the level of the population.
The optimal experimental design for testing the effects of spike rate, irregularity, and synchrony would be to systematically and precisely manipulate each of these variables independently of the others. Unfortunately, there is currently no experimental technique for simultaneously controlling all three spiking parameters with sufficient precision. This challenge has affected all studies to date, including the study of Sarnaik and Raman (Sarnaik and Raman, 2018), which focused on experimental manipulation of synchrony, with less control of spike rate and irregularity. Given such experimental limitations, the computational modeling approach used in our manuscript and by other investigators (Luthman et al., 2011; Steuber et al., 2011) provides a useful complement to experimental recording and stimulation approaches, affording the opportunity to independently manipulate rate, irregularity and synchrony with any desired level of precision.
In the text, we have noted both the strengths and caveats of each approach. As the reviewer suggests, and as we acknowledge in the original and revised manuscripts (Discussion, second paragraph), it is possible that the residual CV2 may not be correlated across neurons at the level of the population, and that if irregularity did matter under these natural conditions, the effect of a single neuron may simply be too small to detect with the residual analysis. It is the preponderance of evidence from recording, stimulation and computational approaches that drives our conclusion, not any single result or observation.
The main focus of our manuscript is the downstream effects of spike irregularity, rather than the related but separate issue of the upstream causes of the level of irregularity. Nevertheless, we have added an additional figure (Figure 1—figure supplement 3,subsection "Mean spike rate and irregularity both vary with oculomotor behavior", last paragraph) to address this issue. This figure directly compares the relationship between firing rate and CV2 observed in the data with the prediction of an inhomogeneous Poisson process modulated by an absolute refractory period. This refractory Poisson model produces an inverse relationship between irregularity and rate, as the reviewer suggests, yet does not quantitatively match the data, providing support for the idea that the refractory period is a contributor, but not the sole contributor to the inverse correlation between firing rate and CV2.
This analysis is included in the revised manuscript (Figure 2—figure supplement 1; see response to reviewer #1 above).
The linear mixed effect model for the data illustrated in Figure 2 was modified to include an interaction term between CV2 and rate. The interaction term did not significantly improve predictions (assessed using a log likelihood ratio between the full model with the interaction term and the model without the interaction term), and did not change the significance of the impact of rate or CV2. The results are now incorporated in the text (subsection "Spike rate, but not irregularity, predicts moment-to-moment variations in eye velocity").
We thank the reviewer for recognizing our contribution to understanding Purkinje cell-movement coupling as "strong and original". We agree that it is important to consider the relevance of the stimulation experiments to physiological conditions. In the relevant region of the cerebellar cortex (the flocculus) and target nucleus (the vestibular nuclei), the mossy fibers are not silent in the absence of movement, but rather are right in the middle of their physiological activity range. Mossy fiber inputs to the flocculus and vestibular nuclei have spontaneous firing rates of ~40-100 Hz (Lisberger and Fuchs, 1978; Sadeghi et al., 2007; Lasker et al., 2008), and increase their firing during vestibular stimuli or eye movements in one direction, and decrease their firing for eye movements in the other direction. Likewise, the floccular Purkinje cells' target neurons in the vestibular nuclei have fairly high firing rates in the absence of eye movements (subsection "Biophysical model of Purkinje cell synaptic transmission", sixth paragraph), and encode eye velocity in opposite directions with bidirectional changes in rate. Thus, the network state during our optogenetic stimulation experiments, which were done in the absence of eye movements, should be roughly in the center of its normal ("physiological") working range.
Nevertheless, in the revised text, we acknowledge the limitations inherent in stimulation experiments (subsection "Biophysical model of Purkinje cell synaptic transmission", last paragraph and Discussion, second paragraph). These limitations were an important motivation for the complementary and more "physiological" recording experiments (Figure 1, Figure 2) which analyze the natural neural activity during oculomotor behavior, during which both the levels of Purkinje cell synchrony and the activity of mossy fibers and other neurons is normal. Together, the convergent evidence from these complementary recording and stimulation approaches make the case that the irregularity of Purkinje cell firing has no detectable impact on eye movements beyond what can be accounted for by the spike rate.
We have revised the text to clarify that we used the Iirreg index to capture the overall impact of irregularity on the mean eye velocity across a range of stimulation frequencies (subsection "Biophysical model of Purkinje cell synaptic transmission", seventh paragraph). In this analysis, we were testing for effects on the mean eye velocity averaged across the duration of the train, rather than the variance of eye velocity, because previous modeling work (Luthman et al., 2011) had predicted an effect of irregularity on the mean firing rate in the Purkinje cells' target neurons.
In the revised manuscript, we also include a new analysis of how increased irregularity may affect the precision (variance) of motor output by increasing the variability of the population rate code (new Figure 6).
As described above, we have revised the manuscript to clarify terminology, and specify that rapid rate coding on time scales faster than an ISI in a single neuron is considered with respect to the average spike rate in the population (subsection "Rapid rate code for eye movements", first paragraph; subsection "Rapid rate coding"; subsection "No evidence for additional influence of spike irregularity").
Hannah L Payne
Department of Neurobiology, Stanford University, Stanford, United States
Conceptualization, Data curation, Software, Formal analysis, Investigation, Visualization, Methodology, Writing—original draft, Writing—review and editing
No competing interests declared
Ranran L French
Department of Brain and Cognitive Sciences, University of Rochester, Rochester, United States
Software, Formal analysis
Christine C Guo
Mental Health Program, QIMR Berghofer Medical Research Institute, Queensland, Australia
Conceptualization, Investigation
TD Barbara Nguyen-Vu
Conceptualization
Tiina Manninen
Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Conceptualization, Software, Formal analysis
Jennifer L Raymond
Conceptualization, Resources, Supervision, Funding acquisition, Investigation, Project administration, Writing—review and editing
[email protected]
Reviewing editor, eLife
"This ORCID iD identifies the author of this article:" 0000-0002-8145-747X
National Science Foundation (DGE-114747)
Stanford University (DARE Doctoral Fellowship Program)
National Science Foundation (0801700)
Academy of Finland (315795)
National Institutes of Health (R01-DC04154)
National Institutes of Health (R01-NS072406)
National Institutes of Health (P30-NS069375)
We thank Mark Goldman, Jay Bhasin, John Huguenard, Sriram Jayabal, Jason Bant, Lane McIntosh, and Donald Payne for helpful discussions and comments on the manuscript; Soon-Lim Shin for early conceptual input; Akira Katoh and Michael Ke for sharing their published electrophysiology data; Max Gagnon for assistance with data analysis; Bob Schneeveis for construction of custom apparatus; and James Dang for technical assistance. This work was supported by the US National Institutes of Health (R01 DC04154 and R01 NS072406 JLR; P30 NS069375); the National Science Foundation Graduate Research Fellowship (DGE-114747; HLP); the National Science Foundation fellowship for Stanford Mind Brain Computation IGERT (0801700; HLP); the Stanford DARE (Diversifying Academia, Recruiting Excellence) Doctoral Fellowship Program (HLP); and the Academy of Finland (decision Nos. 315795 and 320072; TM).
Animal experimentation: All procedures complied with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. Animals were handled strictly according to the guidelines of the institutional animal care and use committee (IACUC) at Stanford University, accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC). Protocols were approved by the Administrative Panel on Laboratory Animal Care at Stanford University (protocol #9143). All surgery was performed under isoflurane anesthesia, and every effort was made to minimize animal suffering.
Senior and Reviewing Editor
Richard B Ivry, University of California, Berkeley, United States
David J Herzfeld, Johns Hopkins University, United States
Received: March 31, 2018
Accepted: April 16, 2019
Version of Record published: May 3, 2019 (version 1)
© 2019, Payne et al.
Purkinje cell
irregularity
temporal code
eye movements
Research organisms
Rhesus macaque
Neuronal integration in the adult mouse olfactory bulb is a non-selective addition process
Jean-Claude Platel et al.
Anterior CNS expansion driven by brain transcription factors
Jesús Rodriguez Curt et al.
Active information maintenance in working memory by a sensory cortex
Xiaoxing Zhang et al.
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Update for November 18, 2020
The FDA rejected the BLA for Sanofi's sutimlimab for the treatment of hemolysis in adult patients with cold agglutinin disease due to problems in a contracted manufacturing facility.
The FDA rejected the BLA for Alkermes' ALKS 3831 a combination of olanzapine and samidorphan) to treat schizophrenia due to tablet coating problems during manufacturing.
The FDA has delayed approval of Bristol Myers Squibb's lisocabtagene maraleucel due to travel restrictions delaying the inspection of the manufacturing plant. A new PDUFA date has not been announced.
Announced Research Updates
Pfizer announced that in the 52-week, 1,233 patient, Phase III, JADE REGIMEN trial, abrocitinib prevented an acute dermatitis flare (loss of at least 50% of the Eczema Area and Severity Index or EASI response seen at week 12 and an IGA score of two or higher) in 81.1% of patients treated with 200 mg and 57.4% of patients treated with 100 mg compared to 19.1% that received placebo in patients with moderate to severe atopic dermatitis.
OncoSec Medical announced interim data from 54 patients enrolled in the Phase IIb, open -label, PISCES/KEYNOTE-695 trial, where treatment with tavokinogene telseplasmid plus pembrolizumab resulted in a 30% overall response rate in patients with unresectable stage III or IV metastatic melanoma.
Amgen and AstraZeneca announced that in the 1,061 patient, 52-week, Phase III NAVIGATOR trial, treatment with tezepelumab reduced the annualized asthma exacerbation rate compared to placebo in patients with severe asthma who were receiving medium to high-dose inhaled corticosteroids plus at least one additional controller medication with or without oral corticosteroids.
Acceleron announced interim data from 10 patients enrolled in the 24-week, 25 patient, Phase II, open-label, SPECTRA trial, where treatment with sotatercept peak resulted in improvements in multiple hemodynamic measures as well as exercise tolerance and exercise capacity in patients with pulmonary arterial hypertension.
MeiraGTx, announced 12-month interim data from a 10 patient, open-label, dose-escalation, Phase I/II trial, where treatment with AAV- RPGR resulted in an improvement in mean retinal sensitivity and low light visual mobility in patients with X-linked retinitis pigmentosa (XLRP).
BrainStorm announced that in a 28-week, 189 patient, Phase III trial, treatment with MSC-NTF did not improve the number of patients that achieved at least a 1.25 point improvement per month in their Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) score compared to placebo in patients with amyotrophic lateral sclerosis (ALS). In the trial, 34.7% of MSC-NTF patients achieved the ALSFRS-R improvement target compared to 27.7% with placebo. The study may have been underpowered due to more placebo patients achieving the ALSFRS-R improvement than anticipated.
CymaBay announced that in the 3-month, 110 patient, Phase III, ENHANCE trial, 78.2% of patients treated with seladelpar 10 mg achieved a composite of a decrease in alkaline phosphatase and total bilirubin compared to 12.5% on placebo in patients with primary biliary cholangitis and an inadequate response or intolerance to ursodeoxycholic acid. CymaBay is evaluating seladelpar as a treatment for primary biliary cholangitis in the 52-week, 180 patient, Phase III RESPONSE trial (NCT04620733).
BeyondSpring announced that in the 221 patient, Phase III PROTECTIVE 2 trial, grade 4 neutropenia was prevented in 31.5% of patients treated with plinabulin plus pegfilgrastim compared to 13.6% with pegfilgrastim alone in patients with breast cancer treated with docetaxel, doxorubicin, and cyclophosphamide.
Published Research Updates
In a 26-week, 243 patient extension of the Phase III trial, 43.5% of patients that continued ravulizumab and 40.3% of patients that switched from eculizumab to ravulizumab achieved LDH normalization. Transfusion was avoided in 73.6% of patients that continued ravulizumab and 67.2% of patients that switched from eculizumab to ravulizumab.
In the 22-week, 8,256 patient, Phase III, GALACTIC-HF trial, 37% of patients treated with omecamtiv mecarbil experienced a composite endpoint of cardiovascular death or heart failure worsening compared to 39.1% with placebo in patients with symptomatic chronic heart failure and an ejection fraction of 35% or less.
In the 516 patient, Phase III, SANDPIPER trial, patients treated with taselisib plus fulvestrant achieved progression-free survival of 7.4 months compared to 5.4 months with fulvestrant alone in patients with estrogen receptor-positive, HER-2-negative, PIK3CA-mutant locally advanced or metastatic breast cancer.
In a 16-week, 272 patient, Phase II trial, the percentage points reduction in LDL over placebo with evinacumab was -56.0 with 450 mg weekly, -52.9 with 300 mg weekly, and -38.5 with 300 mg every two weeks in patients with refractory hypercholesterolemia.
In the 9-month, 1,222 patient, Phase III, SOLOIST-WHF trial, 51% of patients treated with sotagliflozin experienced the composite endpoint of death from cardiovascular causes or hospitalization/urgent visits for heart failure compared to 76.3% with placebo in patients with diabetes and recent worsening heart failure. In the 16-month, 10,584 patient, Phase III, SCORED trial, patients treated with sotagliflozin experienced 5.6 events per 100 patient-years of the composite endpoint of total number of deaths from cardiovascular causes, hospitalizations for heart failure, and urgent visits for heart failure compared to 7.5 events per 100 patient-years with placebo in patients with diabetes and recent worsening heart failure. Both the 22-month SOLOIST-WHF trial and the 33-month SCORED trial were terminated early due to the COVID-19 pandemic and discontinuation of funding from Lexicon and Sanofi.
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Abstract Use of high doses of verapamil in preventive treatment of cluster headache (CH) is limited by cardiac toxicity. We systematically assess the cardiac safety of the very high dose of verapamil (verapamil VHD) in CH patients. Our work was a study performed in two French headache centers (Marseilles–Nice) from 12/2005 to 12/2008. CH patients treated with verapamil VHD (C720 mg) were considered with a systematic electrocardiogram (EKG) monitoring. Among 200 CH patients, 29 (14.8%) used verapamil VHD (877 ± 227 mg/day). Incidence of EKG changes was 38% (11/29). Seven (24%) patients presented bradycardia considered as nonserious adverse event (NSAE) and four (14%) patients presented arrhythmia (heart block) considered as serious adverse event (SAE). Patients with EKG changes (1,003 ± 295 mg/day) were taking higher doses than those without EKG changes (800 ± 143 mg/day), but doses were similar in patients with SAE (990 ± 316 mg/day) and those with NSAE (1,011 ± 309 mg/day). Around three-quarters (8/11) of patients presented a delayed-onset cardiac adverse event (delay C2 years). Our work confirms the need for systematic EKG monitoring in CH patients treated with verapamil. Such cardiac safety assessment must be continued even for patients using VHD without any adverse event for a long time.
Source: Lanteri-Minet M, Silhol F, Piano V, Donnet A. Cardiac safety in cluster headache patients using the very high dose of verapamil (≥720 mg/day). The Journal of Headache and Pain. 2011;12(2):173-176. doi:10.1007/s10194-010-0289-x.
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Background/purpose: The aim of this study was to investigate the role and mechanisms of the formyl peptide receptor (FPR) and the toll-like receptor 9 (TLR9) in hypoxia-induced chemoresistance of human ovarian cancer cells.
Materials and methods: SKOV3 cells were exposed to hypoxia for 24 hours, the supernatant was collected to stimulate normoxia-cultured SKOV3, and the inhibition rate of cell growth was detected with CCK8 test. The agonist of TLR9 CpG ODN and the agonist of FPR fMLF were applied to investigate the chemosensitivity of SKOV3 cells to cisplatin. The cells were also treated with FPR antagonist t-Boc or TLR9 antagonist CQ. Western blot was applied to detect protein levels of FPR, TLR9, MRP, P-gp, p53 and Beclin-1. Immunofluorescence staining was applied to observe the distribution of TLR9 in SKOV3 cells.
Results: Hypoxia exposure reduced the inhibition rate of cisplatin on SKOV3 cells. WB showed that FPR and TLR9 were expressed in human ovarian cancer tissues and SKOV3 cells, and the levels were increased with longer hypoxia time. After SKOV3 was stimulated with fMLF or ODN2006, cisplatin-induced inhibition rate was significantly decreased. tBoc and CQ significantly attenuated hypoxia supernatant-induced chemoresistance of SKOV3 cells. Hypoxia supernatants significantly increased MRP, P-gp, p53 and Beclin-1 proteins in SKOV3 cells, which were significantly reduced by tBoc.
Conclusion: Hypoxia upregulates the expression of FPR and TLR9, and promotes the release of ligands for both receptors in human ovarian cancer cell line. FPR and TLR9 may be noval targets for chemosensitizing to ovarian cancer cells.
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Dr. Theodore A. Bass, University of Florida College of Medicine-Jacksonville, 655 West 8th Street, Jacksonville, Florida 32209.
A 70-year-old Caucasian man with a history of coronary artery disease (CAD) 9 months status post–2-vessel coronary artery bypass grafting (left internal mammary artery to left anterior descending artery and saphenous vein graft to the first oblique marginal artery) performed at an outside hospital was admitted with a non–ST-segment elevation myocardial infarction. He underwent coronary angiography, which showed severe native CAD and both grafts patent. The right coronary artery (RCA) had a severe stenosis in the ostium and proximal segment. Notably, the proximal RCA was characterized by an image suggestive of a perforation with flow into the epicardium leading to a contained pseudoaneurysm (Figure 1A). The patient was sent for a coronary computed tomography scan for further anatomical evaluation, which showed a sternal wire abutting a large 2.2-cm RCA epicardial pseudoaneurysm with mural thrombus (Figure 1B). This finding was likely attributed to vessel injury while suturing the sternum. The decision was to perform percutaneous coronary intervention of the RCA. Following pre-dilatation with a 3.0 mm × 12 mm compliant balloon (Abbott Vascular, Santa Clara, California) inflated up to 16 atm, 2 sequential 3.5 mm × 16 mm GraftMaster covered stents (Abbott Vascular) implanted at 18 atm were required to cover the area of perforation. Post-dilation was performed using a 4.5 mm × 20 mm noncompliant balloon (Boston Scientific, Maple Grove, Minnesota) inflated to 16 atm. Finally, a 4.0 mm × 28 mm REBEL bare-metal stent (Boston Scientific) was implanted at 18 atm extending from the site of perforation to the ostial RCA, followed by post-stent dilation using a 4.5 mm × 12 mm noncompliant balloon (Abbott Vascular) serially inflated up to 20 atm. No further leak was observed on angiography (Figure 1C). The patient was treated with aspirin and clopidogrel. Forty-eight hours after the procedure, right coronary angiography was performed, which showed a patent stent and a very small residual pseudoaneurysm (Figure 1D). The patient remained asymptomatic throughout his hospitalization. This is the first documented angiographic case showing a coronary artery tear complication during open-heart surgery followed by successful percutaneous coronary intervention repair.
(A) Initial angiography with a significant tear and a large pseudoaneurysm of the proximal right coronary artery (RCA). (B) Coronary 3-dimensional computed tomography scan confirming a sternal wire (thick arrow) abutting a large 2.2-cm pseudoaneurysm of the proximal RCA. (C) Coronary angiography following implantation of a 2 GraftMaster (Abbott Vascular, Santa Clara, California) stents and a REBEL bare-metal stent (Boston Scientific, Maple Grove, Minnesota) extending from the proximal RCA to the ostium with no further leak. (D) Follow-up angiography 48 h later confirming stent patency and a very small residual pseudoaneurysm.
Dr. Angiolillo has received consulting fees or honoraria from Amgen, AstraZeneca, Bayer, Biosensors, Chiesi, Daiichi Sankyo, Eli Lilly, Janssen, Merck, PLx Pharma, Pfizer, and Sanofi; honoraria for participation in review activities for CeloNova and St. Jude Medical; and institutional grant support from Amgen, AstraZeneca, Biosensors, CeloNova, CSL Behring, Daiichi Sankyo, Matsutani Chemical Industry Co., Merck, Novartis, and Renal Guard Solutions. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Revision received July 6, 2017.
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Whether it's called carpal tunnel syndrome, repetitive stress injury, or cumulative trauma disorder, wrist, hand, elbow, shoulder, neck and back injuries continue to be an almost unavoidable plague for workers using computers in manufacturing, service and office settings. The latest statistics show that two-thirds of workers will experience a repetitive stress injury as a result of the work they do everyday, costing employers millions in lost time and medical expenses. Ideally we should all try to limit the number of hours we spend plugging away at the keyboard, but unfortunately for most of us that is not an option.
However there are a number of small steps that everyone can take to help to protect your body and prolong your working life. With just a few simple adjustments you can prevent taking unnecessary medications or even surgeries. We have listed some general ergonomic recommendations below, however because everyone has their own personal needs, we recommend having your spine checked by a professional to determine what your specific ergonomic needs may be.
The single most important change you can make without too much difficultly is to ensure that your computer monitor is at eye level or even slight higher to ensure that you are not looking downward all of the time. The monitor should be about 18-30 inches away and positioned along with the keyboard directly in front of you. Frequently used items such as a mouse or phone should be placed within an arms reach, and if possible a headset should be used for the phone.
As for chair recommendations, a chair height that allows for the proper upper body position is of the utmost importance. Your chair should have adjustable arm rests that allows for your shoulders to stay relaxed and your elbows resting at a 90 degree angle, with your knuckles, wrist and top of the forearms forming a straight line. Your feet should be flat on the floor and if the height of your chair does not allow this, a foot rest should be used. Your chairs' backrest should provide firm support for the inward curve of the lower spine (lumbar) and outward curve of the upper spine (thoracic).
Lastly, it is important to monitor the amount of time you spend sitting at your desk. It is important to take at least a short break every 30 minutes, even if you simply stand up and stretch your back, neck and shoulders for 30 seconds. This brief rest will also provide your eyes with the break they require as well.
If these steps do not resolve the symptoms you are feeling a short course of chiropractic care or physical therapy can quickly resolve problems caused by repetitive stress injuries. If these injuries go neglected or untreated for a prolonged period of time, they may worsen enough to require surgery.
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The purpose of our study was to review the postoperation outcome
The purpose of our study was to review the postoperation outcome and incidence of deep vein thrombosis (DVT) in endometrial cancer (EC) patients with or without hypertension, diabetes, and obesity. and boost hospitalization amount of time in matching. VTE is normally a common problem of EC medical procedures with comorbidities, such as for example hypertension and diabetes, and its an extraordinary proportion of occasions taking place after surgery late. worth of <0.05 was considered to be significant statistically. Results Desk 1 shows the distribution of 219 situations of endometrial cancers according to chosen factors. 120 (60%, 120/200) situations received hysterectomy and bilateral salpingo-oophorectomy. 48 (24%, 48/200) situations received hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection. Among these sufferers 30 (15%, 30/200) situations likewise have appendectomy and 3 (1.5%, 3/200) cases also acquired omentum resection. 50 (25%, 50/200) sufferers received hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node biopsy; 3 (1.5%, 3/200) cases acquired high ligation of infundibulopelvic ligament. A couple of 6 (3%, 6/200) Tbx1 situations intraoperative substantial hemorrhage and provided focused erythrocytes 6U and plasma 200 ml, focused erythrocytes 3U respectively. The common operative period was 1.8 hours, loss of blood was 265.7 ml, and hospitalization was 9 times. Postoperative radiotherapy was added in 50 (22.8%) sufferers because of neighborhood recurrence and distant metastasis. Because radiotherapy would work for advanced cancers or sufferers who aren't suitable for medical procedures, 19 (8.7%) sufferers required single rays therapy. Desk 1 Descriptive features of hospitalization ladies in the analysis population There have been no significant distinctions among EC sufferers regarding the indicate age group, body mass index, tumor quality, histology (Desk 1). As showed in Desk 2, there have been no significant distinctions between your five groups regarding operative time, and lymph metastasis. The mean numbers of eliminated pelvic lymph nodes in organizations 1 to 5 had been 11.8, 15.2, 14.9, 14.6, and 10.7, respectively (p=0.102). As well as the indicate numbers of taken out aortic lymph nodes in groupings 1 to 5 had been 10.2, 12.5, 13.7, 11.8, and 9.5, respectively (p=0.221). Furthermore there is a big change in estimated quantity of loss of blood between group 1 and group 5 (p<0.01) (Desk 3). Similarly, the distance of medical center stay significantly elevated among the four groupings with comorbidities in comparison to that of the group without comorbidities. A big change was discovered between group 4 and group 5 (p<0.01) (Desk 4). Desk 2 Operation final result of hospitalization ladies in the analysis population Desk 3 The evaluation of intraoperative loss of blood and medical center stay between your five groups Desk 4 The evaluation of medical center stay between your five groupings We further examined the occurrence of postoperative problem, VTE in the five groupings. Desk 5 demonstrates that VTE happened in 25 sufferers. DVT happened in 22 sufferers, 5 (11.42%) sufferers in group 1, 6 Bumetanide IC50 Bumetanide IC50 (2.74%) individual in group 2, 2 (0.91%) sufferers in group 3, 8 (3.65%) sufferers in group Bumetanide IC50 4, and 1 individual (0.46%) in group 5, respectively. There is a big change in the occurrence of DVT among the 5 groupings (p<0.01) (Desk 6). Furthermore, significant distinctions were discovered between group 5 and group 1, group 2 and group 4, respectively. The occurrence of PE was 1 (4.5%) individual in group 1, 2 (13.3%) sufferers in group 4, and non-e in group 2, 3, and 5. There is a big change in the occurrence of PE between group 5 and group 4. All of the three PE sufferers were dead due to acute onset. Desk 5 Occurrence of postoperative venous thromboembolism in the sufferers with endometrial cancers Desk 6 Postoperative problems in the sufferers with endometrial cancers Discussion Endometrial cancers may be the most common gynecologic malignancy world-wide. This scholarly research was retrospective to review the procedure strategies, postoperation final results and deep.
Posted in Other
Tagged: Bumetanide IC50, Tbx1.
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Trial of telomerase inhibitors points to lasting treatments for myeloproliferative disorders
Tami Dennis
Study in New England Journal of Medicine highlights City of Hope research on novel-acting drug
DUARTE, Calif., September 2, 2015 — A multinational team of physicians and scientists from City of Hope, the San Francisco Bay area, and Europe recently reported success of a phase II clinical trial of a novel drug against essential thrombocythemia (ET), one of three myeloproliferative neoplasms (MPNs). That study, published in the Sept. 3 edition of the New England Journal of Medicine, represents the first human trial of a drug targeting telomeres in a blood neoplasm and paves the way toward more durable treatments of these disorders.
MPNs, which also include myelofibrosis and polycythemia vera, are blood diseases akin to leukemia, each marked by overproduction of a particular blood cell type. ET patients, for example, make too many platelets, cells essential for blood clotting, which puts them at risk for thrombosis and bleeding. Even when effective, existing ET treatments reduce platelet counts but do not provide a long-lasting cure, and some patients are resistant to them. A small percentage of patients progresses to acute leukemia.
The new study reports that all 18 ET patients treated with the drug imetelstat exhibited decreased platelet levels, and 16 showed normalized blood cell counts. Eight patients participated at City of Hope and the rest were treated at hospitals in Germany and Switzerland. Most participants experienced only transient mild or moderate adverse affects. City of Hope physician David Snyder, M.D, associate chair and professor in City of Hope's Department of Hematology & Hematopoietic Cell Transplantation, was senior author of the paper.
"Our trial was a first look at what happens when you treat ET patients with a drug that has a totally novel mechanism of action," said Snyder, a co-principal investigator on the trial. "These studies open the door to test imetelstat effects in myelofibrosis, an MPN whose prognosis is much worse than ET."
Imetelstat was developed by the Bay-area biotech company Geron, which sponsored the study and whose scientists were co-authors. Imetelstat inhibits the enzyme telomerase, which elongates telomeres — repetitive DNA and RNA structures that encase chromosome tips. Telomere length serves as a molecular clock to control cell growth: Normally, as cells age, telomeres shorten, slowing the overall rate of cell division. However, telomerase becomes overactive in 90 percent of all cancers, keeping telomeres from eroding and permitting uncontrolled tumor cell proliferation.
Previously, researchers had treated cultured human cells derived from breast or blood tumors with imetelstat and observed shortened telomeres and decreased tumor cell growth, sparking intense interest in anti-telomerase drugs as therapeutics. Imetelstat is the first anti-telomerase molecule to be evaluated clinically.
The 18 ET patients chosen for the study displayed high platelet counts at study entry, and many were resistant or intolerant of other ET treatments. Initially, participants received weekly imetelstat injections, and most were treated less frequently as the trial progressed. Not only did 100 percent show decreased platelet counts but many maintained that response for more than a year while on the drug.
"Patients at City of Hope generally tolerated the infusions well," Snyder said. "Some experienced flu-like symptoms a few days later, which then cleared. For most, things got easier over time." All patients, however, exhibited elevated liver enzyme levels, which normalized once treatment ended, and one elderly patient died of liver failure during the trial and imetelstat could not be conclusively excluded as a contributory agent. The Food and Drug Administration, however, concluded that the benefits of drug treatment outweighed any risk of harm.
Nonetheless, Snyder said that "more dots need to be connected" to nail down how imetelstat acts molecularly. For example, it remains to be proven that positive patient responses were attributable to telomerase inhibition or how and whether positive responses correlate with particular mutations associated with MPN disease.
"We also don't yet know whether imetelstat eradicates early progenitor cells or just more mature blood cells," he said. However, patients' platelet levels rose after drug withdrawal. "That suggests that in ET, imetelstat may target an early stem cell population within bone marrow, but not irreversibly."
Killing those cells will likely be required for a long-term anti-cancer response, or remission. Intriguingly, a pilot study conducted at Mayo Clinic hinted that imetelstat can promote remission in a subset of myelofibrosis patients. Snyder said this discovery, also reported in the Sept. 3 issue of the New England Journal of Medicine, shifts the focus of anti-telomerase therapies for MPNs from ET to myelofibrosis. Both studies were released online Sept. 2.
Gabriela M. Baerlocher, M.D., the study's lead author and a hematologist at University Hospital and the University of Bern in Switzerland, concurred. "There is a greater need for drugs in more devastating diseases like myelofibrosis, where there are no other good treatment options," she said. "The goal is now to confirm these effects in a larger cohort of patients and evaluate if imetelstat has effects in other precancerous or malignant blood diseases."
Geron in partnership with Janssen Biotech Inc., is now conducting such trials focusing on myelofibrosis.
Snyder, whose practice includes a sizeable proportion of MPN patients, eagerly awaits their outcome. "My patients get really excited when I tell them about the Mayo study that showed remission in some patients," Snyder said. "This drug has gotten a lot of attention in the patient population. We're anxious to get these studies going."
Other collaborating authors include Elisabeth Leibundgut, PharmD., and Michael Daskalakis, M.D., of University Hospital and University of Bern, Switzerland; Oliver Ottmann, M.D., of Johann Wolfgang Goethe University in Frankfurt, Germany; Gary Spitzer, M.D., of Upstate Oncology Associates, Greenville, South Carolina; Olatoyosi Odenike, M.D., of University of Chicago; Michael McDevitt, M.D., Ph.D., of Johns Hopkins University School of Medicine, Baltimore; Alexander Röth, M.D., of University Hospital in Essen, Germany; Bart Burington, Ph.D., and Monic Stuart, M.D. of Geron in Menlo Park, California.
Snyder is supported by City of Hope's Gehr Family Center for Leukemia Research and the Hematologic Malignancies and Stem Cell Transplantation Institute.
City of Hope is an independent research and treatment center for cancer, diabetes and other life-threatening diseases. Designated as a comprehensive cancer center, the highest recognition bestowed by the National Cancer Institute, City of Hope is also a founding member of the National Comprehensive Cancer Network, with research and treatment protocols that advance care throughout the nation. City of Hope's main hospital is located in Duarte, California, just northeast of Los Angeles, with clinics in Antelope Valley and South Pasadena. It is ranked as one of "America's Best Hospitals" in cancer by U.S. News & World Report. Founded in 1913, City of Hope is a pioneer in the fields of bone marrow transplantation and genetics.
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Q: Moderator declined an altogether wrong answer I recently flagged this answer, used the other option and put the following as the text:
This answer is accepted, but completely wrong.
And got this as the response:
declined - flags should not be used to indicate technical inaccuracies, or an altogether wrong answer
The answer is indeed incorrect, as it says that something isn't possible, when it is completely possible, and has been right from the beginning of Java.
Could someone tell me if this was an error on my part, or a mistake by the moderator? I'm not blaming anyone, just wanted to be sure I'm not doing anything wrong by flagging such answers.
A: If an answer is wrong then downvote it and leave a comment. Flagging as not an answer should only be used for posts like
*
*Thank you
*Me too
*Did someone find a solution
and so on: Posts that are really not an answer.
A: I think this is most likely a simple misreading of the flag decline reason:
declined - flags should not be used to indicate technical
inaccuracies, or an altogether wrong answer
In other words there is no discrepancy between what you flagged and the moderator's response.
For discussion of the problem and the best things to do for accepted answers that are incorrect, see the linked FAQ answers. To summarise from the second FAQ post:
*
*Answer the question - or better still upvote the correct answers to
the question.
*Include in your answer explicit reasoning why the other
answers are wrong. Don't be personal or hostile about it, but give
enough evidence to convince someone coming to the site in the future.
If you need to post a new answer for this then do so.
*Downvote
incorrect answers.
*Leave a comment on each incorrect answer, either
just referring to your answer or briefly refuting the relevant point.
*If the accepted answer is dangerous edit the question and chuck in a
warning.
*If the accepted answer is dangerous and the person asking the
question has not fixed it in 24 hours downvote the question.
However it is not encouraged to flag such incorrect choices, as acceptance is down to the question answer to decide whether the problem was fixed for them in their case (which does obviously fall down if the answer is as you say impossible, but hopefully that's the minority of cases). The only recourse a moderator would have is to delete the answer, which isn't really ideal for anybody.
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About Media Relations
Cornell experts available to discuss coronavirus vaccine
Gillian Smith
[email protected]
If you are interested in other angles, please find experts on science and public health implications of coronavirus, the pandemic's impact on the economy and industries, COVID's effects on countries around the world and broader societal impact.
Luis Schang
Professor of Chemical Virology
Dr. Luis Schang is a molecular virologist interested in the interactions between viruses and cells, interactions which determine the outcomes of the infection and, consequently, pathogenicity. His research answers fundamental questions on molecular virology while identifying biologically active small molecule scaffolds that may be developed as antivirals. He is available to discuss virology and the science of how vaccines work.
Sarah Kreps
Professor of Government
Sarah Kreps recently published a study in JAMA Network Open showing that if an initial COVID-19 vaccine is about as effective as a flu shot, uptake by the American public may fall far short of the 70% level needed to achieve herd immunity. She says a highly effective vaccine exceeding most prior estimates could be a game changer with the public.
Hector Aguilar-Carreno
Associate Professor of Microbiology & Immunology
Hector Aguilar-Carreno's research focuses on the search for antiviral agents with broad antiviral applications, with a special interest in those to be used against enveloped viruses. He is available to discuss the work he is doing on a vaccine for COVID-19 and the science behind vaccines in general.
Douglas L. Kriner
Douglas Kriner recently published a study in JAMA Network Open showing that if an initial COVID-19 vaccine is about as effective as a flu shot, uptake by the American public may fall far short of the 70% level needed to achieve herd immunity. He says the research shows these efficacy levels would play a key role in convincing a skeptical public to take the vaccine.
Sean Nicholson
Professor of Policy and Analysis Management, Director of the Sloan program
Sean Nicholson is currently conducting research in three areas: the causes of regional variations in medical spending; the value of new medical technologies; and innovation in the pharmaceutical and biotechnology industries. He is available to discuss the development of COVID-19 vaccines from a variety of perspectives, including health care systems, insurance companies, and policies. He can also weigh in on the topic of vaccine distribution.
Assistant Professor of Policy Analysis & Management
Colleen Carey's research informs the design of publicly-subsidized health insurance markets such as the Affordable Care Act marketplaces. She is available to discuss the development of COVID-19 vaccines from a variety of perspectives, including health care systems, insurance companies, and policies. She can also weigh in on the topic of vaccine distribution.
Cynthia Leifer
Associate Professor of Immunology
Cynthia Leifer, associate professor immunology, is available to discuss molecular biology and cell biology, and how that area of science is important in developing vaccines. She has also done a lot of work on talking about why people choose to not be vaccinated as well as communication around it.
Cornell University has television, ISDN and dedicated Skype/Google+ Hangout studios available for media interviews.
312 College Ave. · Cornell University
[email protected]
@CornellMedia
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CQC praise for Jubilee ward
Jubilee Ward has received a glowing report following a recent inspection by the Care Quality Commission (CQC) into five key indicators on safety and quality.
Following a routine inspection in April, the CQC concluded the Jubilee Ward – a UCLH service at St Pancras Hospital - met the standards for: respecting and involving people who use the services; their care and welfare; cleanliness and infection control; staffing; and assessing and monitoring the quality of service provision.
The inspectors reviewed treatment records and spoke to six patients who were "very positive" about their experiences. 'Excellent. Tip-top. Top class' 'the ward is very clean', 'the nurses are nice' were just a few of the patient comments recorded.
Jubilee Ward provides care for up to 17 patients who are medically stable and are awaiting discharge or transfer to other services. It opened its doors in January 2013 to ease the pressure on acute beds in the University College Hospital tower as part of the UCLH's Flow programme.
The ward is led and managed by matron Josie Gladney, ward sisters Sharon Lynagh, Rebecca Maud and Cliona Curran and deputy ward sister Victoria Banerjee.
Matron Josie Gladney said: "The results are testament to the passion and hard work of the nursing staff to drive though improvements in providing care to one our most vulnerable patient groups."
Initially introduced as a pilot, it will now become a permanent service.
Sharon Lynagh said: "It's a real joy to get such positive outside feedback – particularly when it is about a brand new unit built up from scratch. Everyone is delighted and it's a reflection on the hard work of colleagues in the Jubilee Ward, T7 and across the multidisciplinary team.
"We are planning to celebrate!"
Some of the CQC key findings included:
Respecting and involving people who use services
Nurses respected patients' privacy, dignity and independence when providing personal care. Patients were given appropriate information and support regarding their care or treatment. Diversity and human rights were respected. Food options are available and there is access to interpreters if required.
Care and welfare of people who use services
Care and treatment was planned and delivered in a way that was intended to ensure people's safety and welfare. Calls bells were answered promptly, choice of food was good, staff were supportive and responsive to patients. Medical progress notes were detailed and recorded consistently and assessment notes took into account a wide range of individual needs encompassing emotional, eating and drinking requirements and on-going support needed.
Cleanliness and infection control
Clean, hygienic environment with effective systems in place to reduce the risk and spread of infection.
There were enough qualified, skilled and experienced staff to meet people's needs.
Assessing and monitoring the quality of service
Effective system is in place and there is evidence that learning from incidents/investigations led to appropriate changes being implemented.
For initial advice on referrals to Jubilee Ward contact the integrated discharge team at University College Hospital on 07892 147773 or 07852 220066.
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What does it mean when you urinate every 2 hours?
Is it normal to pee every 2 hours?
What causes a person to urinate every 2 hours?
Is peeing a lot a symptom of Covid-19?
When should I worry about frequent urination?
Is peeing every 2 hours normal?
How many hours apart is it normal to pee?
What are signs and symptoms of the coronavirus disease?
In what conditions does COVID-19 survive the longest?
What are the organs most affected by COVID‐19?
Can people with mild COVID-19 symptoms recover at home?
Several factors may be linked to frequent urination, such as: Infection, disease, injury or irritation of the bladder . Conditions that increase urine production. Changes in muscles, nerves or other tissues affecting bladder function.
It's considered normal to have to urinate about six to eight times in a 24-hour period . If you're going more often than that, it could simply mean that you may be drinking too much fluid or consuming too much caffeine, which is a diuretic and flushes liquids out of the body.
However, frequent urination can be linked to other health issues that aren't normal parts of life and don't fade over time. It can be a symptom of more serious conditions like diabetes, overactive bladder syndrome, UTIs or prostate problems . Needing to urinate frequently can even disturb your sleep.
Many COVID-19 patients discharged from the hospital have reported severe first-time genitourinary symptoms, including increased frequency, urgency, and nocturia that can cause patients to wake up five time a night, Michael B.
Make an appointment with your doctor if you're urinating more frequently than usual and if: There's no apparent cause, such as drinking more total fluids, alcohol or caffeine . The problem disrupts your sleep or everyday activities.
This also applies to normal urinary frequency. For most people, the normal number of times to urinate per day is between 6 – 7 in a 24 hour period . Between 4 and 10 times a day can also be normal if that person is healthy and happy with the number of times they visit the toilet.
Ideally, experts said adults should be urinating about every three to four hours while they're awake, though the frequency may change depending on how much and what you're drinking or eating, or whether you're pregnant.
Signs and symptoms include respiratory symptoms and include fever, cough and shortness of breath. In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome and sometimes death.
Standard recommendations to prevent the spread of COVID-19 include frequent cleaning of hands using alcohol-based hand rub or soap and water; covering the nose and mouth with a flexed elbow or disposable tissue when coughing and sneezing; and avoiding close contact with anyone that has a fever and cough.
Coronaviruses die very quickly when exposed to the UV light in sunlight. Like other enveloped viruses, SARS-CoV-2 survives longest when the temperature is at room temperature or lower, and when the relative humidity is low ( 50%).
The lungs are the organs most affected by COVID‐19
People with mild symptoms who are otherwise healthy should manage their symptoms at home. On average it takes 5–6 days from when someone is infected with the virus for symptoms to show, however it can take up to 14 days.
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