Clan CD cysteine peptidases of parasitic protozoa

Parasitic protozoa contain an abundance of cysteine peptidases that are crucial for a range of important biological processes. The most studied cysteine peptidases of parasitic protozoa belong to the group of papain-like enzymes known as clan CA. However, several more recently identified cysteine peptidases differ fundamentally from the clan CA enzymes and have been included together in clan CD. Enzymes of this clan have now been identified in parasitic protozoa. Many have important roles and also differ significantly from known mammalian counterparts. The main characteristics of clan CD enzymes are outlined here, in particular glycosylphosphatidylinositol (GPI):protein transamidase, metacaspase and separase, and their differences from the clan CA enzymes are described.     

2,3,5,6-Tetrafluorophenyl N-(S-benzoylthioacetyl)glycylglycyl- p-aminobenzoate, a heterobifunctional (99m)Tc ligand for precomplexed antibody labeling

Heterobifunctional (99m)Tc ligands are useful for antibody labeling using the precomplexation route. The aim of this work was to synthesize a ligand, which has sufficient chemical stability to be complexed with (99m)Tc without inactivating the reactive conjugation group. Using 2,3,5,6-tetrafluorophenyl N-(S-benzoylthioacetyl)glycylglycyl-p-aminobenzoate (OC2) >60% of the (99m)Tc complex was obtained at 80 degrees C in 20 min, which was separated from the free ligand and impurities by HPLC. After solvent evaporation, (99m)Tc-OC2 was conjugated with the monoclonal antibody mAb425 in 50% radiochemical yield. In all, the labeling method required about 1 h preparation time. The immunoreactive fraction of the (99m)Tc-OC2 mAb425 conjugate was 81%, indicating preserved binding capability after conjugation. Compared to recently described methods, which need in situ activation of the (99m)Tc complex, the application of OC2 saved time and reduced the number of manipulations with radioactive material.     

Comparison of three pyrethroid treatments of top-sheets for malaria control in emergencies: entomological and user acceptance studies in an Afghan refugee camp in Pakistan

Insecticide-treated bedding materials (sheets and blankets) could be protective against vectors of malaria and leishmaniasis--especially in complex emergencies, epidemics and natural disasters where people are more likely to sleep in exposed situations. Comparison of cotton top-sheets impregnated with different pyrethroids (permethrin 500 mg/m2, deltamethrin 25 mg/m2 or alphacypermethrin 25 mg/m2) for effectiveness against mosquitoes (Diptera: Culicidae) was undertaken in a refugee camp in Pakistan. Predominant species encountered were Anopheles stephensi Liston, An. pulcherrimus Theobald, An. nigerrimus Giles, Culex quinquefasciatus Say, Cx. tritaeniorhynchus Giles and other culicine mosquitoes. All three pyrethroid treatments performed significantly better than the untreated sheets in deterrence and killing of mosquitoes. No significant differences were found between the three insecticides tested in terms of entomological effect. Washing of the treated sheets greatly reduced their effectiveness. In a user acceptance study conducted among 88 families (divided into four groups), six families complained of irritation of the skin and mucous membranes. Of these reports, one was from the placebo group (using untreated sheets) and the other five (5/22=23%) from families using deltamethrin-treated sheets. All families allocated to permethrin and alphacypermethrin groups declared an appreciation for the intervention and reported no side-effects. Ten of the placebo group disliked the intervention, citing no prevention of mosquito biting as the reason. Side-effects associated with deltamethrin indicate that alphacypermethrin and permethrin are more appropriate first choice insecticides for treatment of sheets and blankets.     

Role of heme oxygenases in sepsis-induced diaphragmatic contractile dysfunction and oxidative stress

Heme oxygenases (HOs), essential enzymes for heme metabolism, play an important role in the defense against oxidative stress. In this study, we evaluated the expression and functional significance of HO-1 and HO-2 in the ventilatory muscles of normal rats and rats injected with bacterial lipopolysaccharide (LPS). Both HO-1 and HO-2 proteins were detected inside ventilatory and limb muscle fibers of normal rats. Diaphragmatic HO-1 and HO-2 expressions rose significantly within 1 and 12 h of LPS injection, respectively. Inhibition of the activity of inducible nitric oxide synthase (iNOS) in rats and absence of this isoform in iNOS(-/-) mice did alter sepsis-induced regulation of muscle HOs. Systemic inhibition of HO activity with chromium mesoporphyrin IX enhanced muscle protein oxidation and hydroxynonenal formation in both normal and septic rats. Moreover, in vitro diaphragmatic force generation declined substantially in response to HO inhibition both in normal and septic rats. We conclude that both HO-1 and HO-2 proteins play an important role in the regulation of muscle contractility and in the defense against sepsis-induced oxidative stress.