Increasing tetrahydrobiopterin in endothelial cells by augmenting the levels of the biosynthetic enzyme GTPCH can maintain endothelial nitric oxide synthase function in experimental models of disease states such as diabetes, atherosclerosis, and hypoxic pulmonary hypertension. However, treatment of people with existing coronary artery disease with oral tetrahydrobiopterin is limited by oxidation of tetrahydrobiopterin to the inactive form, dihydrobiopterin, with little benefit on vascular function. Neuroprotection in prenatal hypoxia
Depletion of tetrahydrobiopterin occurs in the hypoxic brain and leads to toxin production. Preclinical studies in mice reveal that treatment with oral tetrahydrobiopterin therapy mitigates the toxic effects of hypoxia on the developing brain, specifically improving white matter development in hypoxic animals. Programmed cell death
GTPCH (GCH1) and tetrahydrobiopterin were found to have a secondary role protecting against cell death by ferroptosis in cellular models by limiting the formation of toxic lipid peroxides. Tetrahydrobiopterin acts as a potent, diffusable antioxidant that resists oxidative stress and enables cancer cell survival via promotion of angiogenesis. References
Further reading
External links
"Sapropterin". Drug Information Portal. U.S. National Library of Medicine. "Sapropterin dihydrochloride". Drug Information Portal. U.S. National Library of Medicine.
Boutonneuse fever (also called, Mediterranean spotted fever, fièvre boutonneuse, Kenya tick typhus, Indian tick typhus, Marseilles fever, or Astrakhan fever) is a fever as a result of a rickettsial infection caused by the bacterium Rickettsia conorii and transmitted by the dog tick Rhipicephalus sanguineus. Boutonneuse fever can be seen in many places around the world, although it is endemic in countries surrounding the Mediterranean Sea. This disease was first described in Tunisia in 1910 by Conor and Bruch and was named boutonneuse (French for "spotty") due to its papular skin-rash characteristics. Presentation
After an incubation period around seven days, the disease manifests abruptly with chills, high fevers, muscular and articular pains, severe headache, and photophobia. The location of the bite forms a black, ulcerous crust (tache noire). Around the fourth day of the illness, a widespread rash appears, first macular and then maculopapular, and sometimes petechial. Diagnosis
The diagnosis is made with serologic methods, either the classic Weil–Felix test, (agglutination of Proteus OX strains), ELISA, or immunofluorescence assays in the bioptic material of the primary lesion. The Weil–Felix test demonstrated low sensitivity (33%) in diagnosing acute rickettsial infections and low specificity, with a positive titre of 1:320 seen in 54% of healthy volunteers and 62% of non-rickettsial fever patients. Therefore, the use of the WFT should be discouraged in the diagnosis of acute rickettsial infections. Treatment
The illness can be treated with tetracyclines (doxycycline is the preferred treatment), chloramphenicol, macrolides, or fluoroquinolones. See also
Rocky Mountain spotted fever

References


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