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At least 667 records · Page 37Linked to original sources
PubMed1992

Early enhanced growth of the digestive gland of Biomphalaria glabrata infected with Schistosoma mansoni: side effect or parasite manipulation?

We carried out a comparative study of the dynamics of the sporocyst population and the growth rate of the host habitat (digestive and genital gland) within the Schistosoma mansoni/Biomphalaria glabrata system during monomiracidial infections. The volume of the digestive gland increased sharply during the first 2 weeks of infection and then decreased at 2-4 weeks post-infection during the exponential growth phase of the sporocyst infrapopulation. The effects of the parasite on the development of the host's genital gland resulted in a slowing of the growth of the ovotestis. These interactions, related to the demographic processes involved in the intramolluscal development of the parasite population, were interpreted in relation to the spatial and energy constraints imposed by the developmental needs of both the parasite and the host.

Animals↗
PubMed2000

Synthesis of new uracil-5-sulphonamide-p-phenyl derivatives and their effect on Biomphalaria alexandrina snail's nucleoproteins.

In continuation of the previous work (Fathalla, 1992) on the synthesis of some heterocycles containing uracil moiety, we report herein the incorporation of uracil moiety into cyanopyridine thione, thiosemecarbazone, semicarbazone, cyanopyridine, aminocyano pyridine, isoxazoline, pyrazoline, pyrimidine, triazolo pyrimidine, pyran, selena and thiazole derivatives which might modify their biological activities. The biological studies revealed that the chemical compound III f showed high molluscicdal activity than other compounds. The profile of the nucleoprotein extracted from chemically (compound IIIc, e, f and g) treated or UV-irradiated B. alexandrina snails did not show appreciable differences when compared to non-treated (native) snails by using SDS-PAGE, where no obvious qualitative or quantitative differences were observed. Immunization of experimental animals with the nucleoprotein extracted from native, chemically (compound III f & g) treated or physically treated B. alexandrina snails induced significant protection against challenge with normal S. mansoni cercariae, as compared to the non-immunized challenged control. As well as, a decrease in the number of granuloma formation and the size range of granuloma was also observed in immunized animals. It is concluded that, compounds III f and g have a potent molluscicidal activity. They also induced chemical modification comparable to that induced by physical treatment in the snail's nucleoprotein, which could possibly be used in immunization against S. mansoni infection.

Animals↗
PubMed2003

Synthesis of new uracil-5-sulfonamide derivatives and immunostimulatory effect of a chemically modified hemolymph of Biomphalaria alexandrina on Schistosoma mansoni infected mice.

Some N-p-substituted phenyl uracil-5-sulphonamide derivatives have been synthesized to be evaluated as molluscicides against Biomphalanaria alexandrina snails, the intermediate host of Schistosoma mansoni. Schistosoma mansoni infected mice were treated with hemolymph obtained from pre-treated Biomphalana alexandrina snails with the products 4a, 10a, 10b and 4b or obtained from non-treated snails. The selection of the concentration based on the predetermined dose which caused mortality of less than 50% of snails/24 h. LC50 of compounds 4a, 10a, 10b and 4b was 50, 100, 200 and 50 ppm respectively. The result showed that immunostimulatory effect of treated hemolymph with compounds 4a, 10a and 4b was related to significant protective effects (44.4, 34.6 and 50.4% reduction in worm burden respectively). In addition, mean total worm burdens were significantly reduced in non treated hemolymph by 33.8%. The effect of hemolymph obtained from treated or non treated snails on S. mansoni adult worms antigens was studied by indirect immunofluorescence technique using chronic mouse sera (CMS). The results indicated that there was a strong reaction with epitopes in gut epithelium, tubercles, teigument and subtegumental musculature of untreated and treated S. mansoni adult worms antigens. Therefore, treatment of hemolymph obtained from pre-treated snails with compounds 4a, 10a, and 4b can stimulate specific immune response and induce protective effects against S. mansoni infection.

Adjuvants, Immunologic↗
PubMed1998

Host choice by larval parasites: a study of Biomphalaria glabrata snails and Schistosoma mansoni miracidia related to host size.

Within snail/trematode associations the age/size of the host at infection has consequences with regard to miracidial infection success, further intramolluscan parasite development and reproduction, and the host response, mainly in terms of growth and reproductive effort. Taking into account these differences, we were interested in determining whether miracidia could discriminate and make a choice between snails of different sizes. Using the Schistosoma mansoni/Biomphalaria glabrata system, we compared data on the snail infection rate and the mother sporocyst abundance among three size classes of snails (juvenile, subadult, and adult) exposed separately or together to the parasite larvae. When exposed individually, juvenile snails (3-5 mm) had significantly higher prevalence and abundance values than did subadult snails, followed by adult snails. In contrast, when snails of the three size classes were exposed together in heterogeneous size groups the prevalence and abundance values were always significantly higher for subadult snails of the 7- to 9-mm class than for juvenile and adult snails. A host choice experiment confirmed that significantly more miracidia were attracted by subadult snails, suggesting that the parasite has been selected for specific locating and recognition mechanisms increasing the infection rate of subadult snails when the latter have been exposed in a heterogeneous size group. Selective forces that may be responsible for such a preferential infectivity of the parasite vis-à-vis particular host age/size class are discussed in relation to host resources and host responses.

Animals↗