***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background / Objectives . Vagal block therapy ( vBloc ) is effective for moderate to severe obesity at one year . Subjects/ Methods . The ReCharge trial is a double-blind , r and omized controlled clinical trial of 239 participants with body mass index ( BMI ) of 40 to 45 kg/m or 35 to 40 kg/m with one or more obesity-related conditions . Interventions were implantation of either vBloc or Sham devices and weight management counseling . Mixed models assessed percent excess weight loss ( % EWL ) and total weight loss ( % TWL ) in intent-to-treat analyses . At 18 months , 142 ( 88 % ) vBloc and 64 ( 83 % ) Sham patients remained enrolled in the study . Results . 18-month weight loss was 23 % EWL ( 8.8 % TWL ) for vBloc and 10 % EWL ( 3.8 % TWL ) for Sham ( P < 0.0001 ) . vBloc patients largely maintained 12-month weight loss of 26 % EWL ( 9.7 % TWL ) . Sham regained over 40 % of the 17 % EWL ( 6.4 % TWL ) by 18 months . Most weight regain preceded unblinding . Common adverse events of vBloc through 18 months were heartburn/dyspepsia and abdominal pain ; 98 % of events were reported as mild or moderate and 79 % had resolved . Conclusions . Weight loss with vBloc was sustained through 18 months , while Sham  regained weight between 12 and 18 months . vBloc is effective with a low rate of serious complications BACKGROUND A laparoscopically implantable electrical device that intermittently blocks both vagi near the esophagogastric junction led to significant excess weight loss ( EWL ) in an initial clinical trial in obese patients . The study objective was to optimize therapy algorithms and determine the EWL achieved with a second-generation device at university hospitals in Australia , Norway , and Switzerl and . METHODS Data acquired during the initial clinical trial were analyzed and subsequently used to select alternative electrical algorithms . In the second trial , vagal blocking using one selected therapy algorithm was initiated 2 weeks after implanting the second-generation device . The patients were followed up for 6 months to assess the EWL and safety , including adverse events . RESULTS In the initial clinical trial , vagal blocking algorithm duration s of 90 - 150 s were associated with greater EWL compared with either shorter or longer algorithm duration s ( P<.01 ) . The second trial enrolled 27 patients ( mean body mass index 39.3+/-.8 kg/m2 ) to evaluate a 120-s blocking algorithm . At 6 months , greater EWL was achieved ( 22.7%+/-3.1 % , n=24 ) compared with the initial study and first-generation device ( 14.2%+/-2.2 % , n=29 , P=.03 ) . In both trials , an association was found between the number of 90 - 150-s algorithms delivered daily and greater EWL ( P=.03 ) . No deaths , unanticipated device-related adverse events , or medically serious adverse events were associated with the device . CONCLUSION This second-generation vagal blocking device , using a therapy algorithm of 120-s duration , result ed in a clinical ly acceptable safety profile and significantly greater EWL compared with the first-generation device delivering a wider range of therapy algorithm duration BACKGROUND A new medical device uses high-frequency electrical algorithms to create intermittent vagal blocking ( VBLOC therapy ) . The aim is to assess the effects of vagal blocking on excess weight loss ( EWL ) , safety , dietary intake , and vagal function . METHODS An open-label , 3-center study was conducted in obese subjects ( body mass index [ BMI ] 35 - 50 kg/m(2 ) ) .  Electrodes were implanted laparoscopically on both vagi near the esophagogastric junction to provide electrical block . Patients were followed for 6 months for body weight , safety , electrocardiogram , dietary intake , satiation , satiety , and plasma pancreatic polypeptide ( PP ) response to sham feeding . To specifically assess device effects alone , no diet or exercise programs were instituted . RESULTS Thirty-one patients ( mean BMI , 41.2 + /- 1.4 kg/m(2 ) ) received the device .  Mean EWL at 4 and 12 weeks and 6 months after implant was 7.5 % , 11.6 % , and 14.2 % , respectively ( all P < .001 ) ; 25 % of patients lost > 25 % EWL at 6 months ( maximum , 36.8 % ) . There were no deaths or device-related serious adverse events ( AEs ) . Calorie intake decreased by > 30 % at 4 and 12 weeks and 6 months ( all P < or= .01 ) , with earlier satiation ( P < .001 ) and reduced hunger ( P = .005 ) . After 12 weeks , plasma PP responses were suppressed ( 20 + /- 7 vs 42 + /- 19 pg/mL ) . Average percent EWL in patients with PP response < 25 pg/mL was double that with PP response > 25 pg/mL ( P = .02 ) . Three patients had serious AEs that required brief hospitalization , 1 each for lower respiratory tract , subcutaneous implant site seroma , and Clostridium difficile diarrhea . CONCLUSIONS Intermittent , intra-abdominal vagal blocking is associated with significant EWL and a desirable safety profile AIMS Uncoordinated contraction of the external urethral sphincter is prevalent in individuals with spinal cord injury and can prevent bladder voiding . The aim of this study was to demonstrate that complete and reversible sinusoidal high frequency alternating current ( HFAC ) conduction block of the pudendal nerves ( PN ) can eliminate external urethral sphincter activation and produce low residual bladder voiding . METHODS In four cats , tripolar nerve cuff electrodes were implanted bilaterally on both pudendal nerves and on both extradural S2 roots . Bladder and urethral pressures , bladder volumes and flow were recorded . Bilateral HFAC was applied to determine voltage and frequency parameters result ing in bilateral PN conduction block . Sacral root stimulation provided bladder activation . R and omized sets of voiding trials were conducted with and without HFAC PN block . Additional voiding trials were conducted following bilateral PN neurotomy to eliminate somatic sphincter resistance and provide an estimate of voiding with complete block . RESULTS Effective bilateral PN block and voiding was obtained in three of four animals . Application of bilateral PN HFAC stimulation improved voiding from 2 + /- 4 % to 77 + /- 18 % of the initial bladder volume and significantly ( P < 0.001 ) reduced maximum bladder pressure during voiding . Voiding in trials with PN block was not significantly different from voiding following PN neurotomy ( 82 + /- 19 % , P = 0.51 ) . CONCLUSIONS These results demonstrate that bilateral HFAC block of the PN can produce effective voiding . Neural prostheses using this approach may provide an alternative method for producing micturition for people with spinal cord injury OBJECTIVE To investigate the effect of unmodulated 5-kHz alternating current on mechanical pain threshold ( MPT ) , heat pain threshold ( HPT ) , tactile threshold ( TT ) , and peripheral nerve conduction ( PNC ) compared with transcutaneous electrical nerve stimulation ( TENS ) and sham stimulation . SETTING National referral center . DESIGN R and omized , double-blind , placebo-controlled crossover trial . PARTICIPANTS Healthy volunteers ( N=38 ) . No dropouts or adverse events were reported . INTERVENTION TENS , unmodulated 5-kHz currents , and sham stimulation were applied on the radial nerve for 20 minutes with a 24-hour washout period between them and concealed intervention allocation . MAIN OUTCOME MEASURES Four measures were taken : before , during , and 2 after the interventions . Algometry was used to assess MPT , a Peltier thermode for HPT using the method of limits , Von Frey filaments for TT , and radial nerve compound action potential . RESULTS No differences were observed on MPT , HPT , and PNC when 5-kHz current and TENS were compared . However , TT increased 56.2mN ( 95 % confidence interval [ CI ] , 28.8 - 83.6 ) in the TENS group compared with the 5-kHz current group during intervention . Compared with sham stimulation during intervention , MPT increased 4.7N ( 95 % CI , 0.3 - 9.2 ) using 5-kHz current and 10.4N ( 95 % CI , 3.5 - 17.3 ) with TENS . TT increased 17.2mN ( 95 % CI , 4.7 - 29.7 ) with 5-kHz current and 73.4mN ( 95 % CI , 47.5 - 99.2 ) with TENS . However , HPT increased 1.0 ° C ( 95 % CI , 0.2 - 2.0 ) only with TENS . For the PNC , no differences were found among the 3 groups . CONCLUSIONS Unmodulated 5-kHz current produced an increase in somatosensory thresholds that was greater than placebo but not when compared with TENS ; however , participants perceived 5-kHz currents to be more comfortable and showed more habituation to them Background Intermittent , reversible intraabdominal vagal blockade ( VBLOC ® Therapy ) demonstrated clinical ly important weight loss in feasibility trials . EMPOWER , a r and omized , double-blind , prospect i ve , controlled trial was conducted in USA and Australia . Methods Five hundred three subjects were enrolled at 15 centers . After informed consent , 294 subjects were implanted with the vagal blocking system and r and omized to the treated ( n = 192 ) or control ( n = 102 ) group . Main outcome measures were percent excess weight loss ( percent EWL ) at 12 months and serious adverse events . Subjects controlled duration of therapy using an external power source ; therapy involved a programmed algorithm of electrical energy delivered to the subdiaphragmatic vagal nerves to inhibit afferent/efferent vagal transmission . Devices in both groups performed regular , low-energy safety checks . Data are mean ± SEM . Results Study subjects consisted of 90 % females , body mass index of 41 ± 1 kg/m2 , and age of 46 ± 1 years . Device-related complications occurred in 3 % of subjects . There was no mortality . 12-month percent EWL was 17 ± 2 % for the treated and 16 ± 2 % for the control group . Weight loss was related linearly to hours of device use ; treated and controls with ≥12 h/day use achieved 30 ± 4 and 22 ± 8 % EWL , respectively . Conclusions VBLOC ® therapy to treat morbid obesity was safe , but weight loss was not greater in treated compared to controls ; clinical ly important weight loss , however , was related to hours of device use . Post- study analysis suggested that the system electrical safety checks ( low charge delivered via the system for electrical impedance , safety , and diagnostic checks ) may have contributed to weight loss in the control group 
    Output:
    
High-frequency alternating currents using frequencies of > 4–5 kHz effectively block nerve conduction .
There is no consensus about the block mechanism , although it has been showed that the frequency is a key factor to produce K+ channels activation or Na+ channels inactivation .
The nerve block produced by currents quickly reverts without causing further damage to the nerve .