A time-course study was carried out to measure the acetylcholinesterase (AChE) gene expression in the brain of female rats exposed to different doses of sarin and physostigmine. Short-term effects were studied with an acute single subcutaneous dose (s.c.) of 80 microg kg(-1) (0.5 x LD(50)) sarin. Cortex and cerebellum showed a significant decline in AChE mRNA expression at 2.5, 24 and 72 h. Biochemical studies showed that plasma butrylcholinesterase (BChE) and brain AChE activities were significantly decreased at 2.5 h, which came back to near control values by 24 h in both cases. For long-term chronic studies, three groups of female rats received daily doses of physostigmine (0.1 mg kg(-1) day(-1)) intramuscularly (i.m.), sarin (15 microg kg(-1) day(-1)) s.c. independently and a combined dose of physostigmine (i.m.) (0.1 mg kg(-1) day(-1)) followed by sarin (s.c.) (15 microg kg(-1) day(-1)) continuously for 30 days. Differential AChE mRNA levels in cortex and cerebellum of rat brain were observed after 30 days and after a lag period of another 30 days with no further administration. Plasma (BChE) and brain (AChE) showed irregular inhibition profile in biochemical studies at 30 days and returned to control levels after 60 days. The acute single subcutaneous administration of sarin for short-term as well as chronic long-term studies showed that AChE inhibition alone does not lead to observed changes in mRNA expression of AChE gene. These observations further suggest that route of administration as well as dose exposure regimen also contributes to the regulation of AChE mRNA expression.
Global efforts have been made towards development of vaccine for prevention of lymphatic filariasis. However, lack of thorough knowledge about developmental biology and pathogenesis of filarial parasite restricts us from developing an effective vaccine. A limited number of immunodominant antigens of human lymphatic filariid Brugia malayi have been characterised; however, none of these recombinant antigens so far induced significant degree of protective immunity to challenge infection. In the present study, we identified a approximately 2.0 Kb cDNA clone by immunoscreening of cDNA library of adult female Brugia malayi. The nucleotide sequence of the identified clone showed 94.3% homology with C-terminal part of myosin heavy chain gene of Brugia malayi. This cDNA insert was sub-cloned into pET28b vector and expressed in BL21(DE3). The recombinant protein was purified to near homogeneity by immobilised metal affinity chromatography (IMAC) with yield of approximately 25 mg/l. The purified protein was recognised in western blot with anti-His tag antibody as also with the antibodies present in the sera of human W. bancrofti patients of all categories and infected/immunized rodent serum demonstrating its functional role. Recombinant myosin induced marked cellular immune response as observed by lymphoproliferation assay. The present findings demonstrate the usefulness of B. malayi recombinant myosin as vaccine candidate against human lymphatic filariasis.
The antifilarial activity of two coumarin derivatives (A, B) and three glycosyl amine derivatives (D, E, F) was evaluated against a subperiodic strain of human lymphatic filarial parasite Brugia malayi by the intraperitoneal route at 50 mg/kg for 5 consecutive days. Of these, the two sugar derivatives (D and E) were selected for evaluation by the oral route based on their microfilaricidal (mild), macrofilaricidal and female worm sterilization efficacy using the i.p. route of administration. Compound E was finally selected for combination therapy on the basis of its microfilaricidal and embryostatic action by the oral route and its spectrum of activity against micro- and macrofilariae including embryostatic activity by the i.p. route. In addition, E also significantly inhibited the parasite DNA topoisomerase II. Compound A, in contrast, led to an enhanced adult worm burden. Compound B was toxic by the i.p. route, killing all of the treated animals before completion of the experiment. Some of these compounds demonstrated significant antifilarial efficacy of varying degree when tested in vitro Compounds B, D and F also killed adult B. malayi in vitro at 100 muM while 50 muM resulted in very slow motility of worms. Compound E in combination with a promising macrofilaricidal benzopyran derivative reported by us recently (compound C) did not show any synergistic or additive effect. These two compounds (C and E) individually on oral administration with either DEC or ivermectin significantly improved microfilaricidal efficacy in terms of intensity and duration of suppressed microfilaraemia. The combination of DEC with compound E demonstrated marginal enhancement in adulticidal efficacy, however, the embryostatic effect of the duo was significantly higher than that exerted by the individual agents. It may thus be inferred that in the absence of an adulticidal antifilarial drug, the use of potential antifilarials in combination with the standard filaricides may yield better results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.