Effect of Niclosamide (Bayluscide WP 70 (R)), Anacardium occidentale hexane extract and Euphorbia splendens latex on behavior of Biomphalaria glabrata (Say, 1818), under laboratory conditions

The repellent effect of the molluscicides Niclosamide (Bayluscide WP 70 (R)), Anacardium occidentale and the latex of Euphorbia splendens on Biomphalaria glabrata was observed through the investigation of the occurrence of escape behavior among molluscs that were exposed to dosages lower than the LD 50. The total number of individuals out of water among the surviving snails in the control group provided a "Natural Escape Index". The comparison between this total and the total number of surviving snails in each group exposed to the different dosages of the molluscicides after 24 hr provided the "Molluscicide Escape Index" and the detection of a "Repellency Range" to these snails. The escape indexes for Niclosamide, A. occidentale and E. splendens were 10, 6.22 and 6.44 respectively. Repellency occurred at the following concentration ranges: 0.01, 0.02 and 0.03 ppm Bayluscide, 0.1, 0.2 and 0.3 ppm A. occidentale and 0.05, 0.10, 0.15 and 0.20 ppm E. splendens. The Natural Escape Index obtained in the control group was zero.

Behavior of Biomphalaria glabrata Say, 1818 (Gastropoda: Planorbidae): I. Morphophysiology of the Mantle Cavity

Using longitudinal and transverse anatomical sections, we observed that the three cristae of the mantle of Biomphalaria glabrata (renal, rectal and dorsolateral cristae) divide the mantle cavity into three chambers which we designated air or pulmonary chamber, water inflow chamber and water outflow chamber. Using videotape filming, we observed the inflow and outflow of air and water into and from the mantle cavity and we related their probable functions such as flotation, oxygen reservoir and transport, excreta circulation and elimination, water skeleton, and modification of specific weight. To determine whether the air bubble may function as a physical gill in this species we submitted three groups of snails to different systems in which water contained the same level of dissolved oxygen whereas the gas phases were atmospheric air, pure nitrogen or pure oxygen. We observed the following parameters: time of permanence on the surface, time of immersion, and frequency at which the snails reached the surface. These results did not demonstrate a physical gill function; morphological analysis of the mantle cavity indicates this possibility

Mechanisms of formation and function of eosinophil lipid bodies: inducible intracellular sites involved in arachidonic acid metabolism

Lipid bodies, inducible lipid-rich cytoplasmic inclusions, are characteristically abundant in cells associated with inflammation, including eosinophils. Here we reviewed the formation and function of lipid bodies in human eosinophils. We now have evidence that the formation of lipid bodies is not attributable to adverse mechanisms, but is centrally mediated by specific signal transduction pathways. Arachidonic acid and other cis fatty acids by an NSAID-inhibitable process, diglycerides, and PAF by a 5-lipoxygenase dependent pathway are potent stimulators of lipid body induction. Lipid body formation develops rapidly by processes that involve PKC, PLC, and de novo mRNA and protein synthesis. These structures clearly serve as repositoires of arachidonyl-phospholipids and are more than inert depots. Specific enzymes, including cytosolic phospholipase A2, MAP kinases, lipoxygenases and cyclooxygenases, associate with lipid bodies. Lipid bodies appear to be dynamic, organelle-like structures involved in intracellular pathways of lipid mobilization and metabolism. Indeed, increases in lipid body numbers correlated with enhanced production of both lipoxygenase- and cyclooxygenase-derived eicosanoids. We hypothesize that lipid bodies are distinct inducible sites for generating eicosanoids as paracrine mediators with varied activities in inflammation. The capacity of lipid body formation to be specifically and rapidly induced in leukocytes enhances eicosanoid mediator formation, and conversely pharmacologic inhibition of lipid body induction represents a potential novel and specific target for anti-inflammatory therapy.

Genetic and Antigenic Analysis of Adenovirus Type 3 Strains Showing Intermediate Behavior in Standard Seroneutralization Test

During an epidemiological survey of acute respiratory infection in Rio de Janeiro, among 208 adenovirus isolates, we found two strains that we were not able, by a standard neutralization procedure, to distinguish between type 3 or 7. However, DNA restriction pattern for the two strains with different enzymes were analyzed and showed a typical Ad3h profile. Using a cross-neutralization test in which both Ad3p and Ad7p antisera were used in different concentration against 100 TCID50 of each adenovirus standard and both isolates, we were able to confirm that the two isolates belong to serotype 3. An hemagglutination inhibition test also corroborated the identification of both strains as adenovirus type 3. Comparing Ad3h and Ad3p genome, we observed 16 different restriction enzyme sites, three of which were located in genomic regions encoding polypeptides involved in neutralization sites

Role of cytokines in the formation and downregulation of hepatic circumoval granulomas and hepatic fibrosis in Schistosoma mansoni-infected mice

Schistosoma mansoni infections are associated with a strong Th2 cytokine response. Treatment of mice with IL-12 or anti-IL-2 or anti-IL-4 before i.v. injection of eggs increased IFN-gamma production and downregulated Th2 responses and pulmonary granuloma size. Conversely, anti-IFN-gamma antibody treatment increased Th2 responses and granuloma size. Similar manipulation produced less dramatic results in infected mice. However, sensitization of mice with eggs + IL-12 before infection augmented the Th1 response and decreased Th2 cytokines, granuloma size and fibrosis. Antisera to IFN-gamma, TNF-alpha or IL-12 during IL-12-egg immunization partly restored granuloma size and fibrosis following infection. Variations in the size of granulomas in acute (8 week) infections may be influenced primarily by the number and state of activation of T cells. In chronic (12-16 week) infections immunologic downmodulation proceeded normally in mice without functional CD8+ cells and in IFN-gamma KO mice but not in B cell KO (muMT) mice or in mice deficient in FcR expression in spite of the fact that these mice downregulated their T cell and cytokine responses. It is evident that the participation of cytokines in granuloma formation and regulation is complicated and that the mechanisms controlling both these phenomena are likely to involve both T cells and antibody/FcR interactions.

Microgeographical patterns of schistosomiasis and water contact behavior; examples from Africa and Brazil

This paper examines the results of spatial (microgeographical) water contact/schistosomiasis studies in two African (Egyptian and Kenyan) and one Brazilian communities. All three studies used traditional cartographic and statistical methods but one of them emploeyd also GIS (geographical information systems) tools. The advantage of GIS and their potential role in schistosomiasis control are briefly described. The three cases revealed considerable variation in the spatial distribution of water contact, transmission parameters and infection levels at the household and individual levels. All studies showed considerable variation in the prevalence and intensity of infection between households. They also show a variable influence of distance on water contact behavior associated with type of activity, age, sex, socioeconomic level, perception of water quality, season and availability of water in the home. Water contact behavior and schistosomiasis were evaluated in the Brazilian village of Nova União within the context of water sharing between household and age/sex groups. Recommendations are made for further spatial studies on the transmission and control of schistosomiasis.

Induction of protective immunity against Schistosoma mansoni infection by antigens purified from PIII, a fraction of adult worm, associated to the downregulation of granuloma formation

This study was performed in order to define Schistosoma mansoni antigens able to function as modulator agents in BALB/c mice granulomatous hypersensitivity to parasite egg. The antigens P-24, P-35 and P-97 were purified by affinity chromatography from a fraction of S. mansoni adult worm antigenic preparation, denominated PIII, involved in the inhibition of granulomatous response to eggs. Immunization of mice with these antigens, in the presence of Corynebacterium parvum and Al(OH)3 as adjuvant, induced a significant protection degree against challenge infection, as observed by the decrease on worm burden recovered from portal system. In vitro blastogenesis assays revealed that purified antigens were able to induce significant proliferation of spleen cells from S. mansoni-infected mice. This protection was correlated to significant decrease in granuloma size induced by PIII. From these results, we concluded that PIII preparation contains antigens capable of mediating protective anti-parasite immunity and down-regulating granulomatous hypersensitivity to S. mansoni eggs.

Population dynamics and feeding behavior of Triatoma brasiliensis and Triatoma pseudomaculata, main vectors of Chagas disease in Northeastern Brazil

Biological parameters of Triatoma brasiliensis and T. pseudomaculata that could influence the epidemiological importance of these insects as vectors of Trypanosoma cruzi were compared. The parameters studied were incubation period, interval between hatching or moulting and first feeding, number of blood meals, development time, mortality, net reproductive rate, instantaneous daily reproductive rate, time-lapse before starting feeding, duration of feeding, blood ingestion capacity, occurrence of defecation and blood ingestion velocity. Most aspects of feeding were similar for the two species, although T. pseudomaculata had a longer life cycle than T. brasiliensis producing one and two generations per year, respectively. The two species had similar instantaneous daily rates of population growth.

Trypanosoma cruzi: genetic group with peculiar biochemical and biological behavior

Thirty-two Trypanosoma cruzi strains, isolated from chronic chagasic patients in the northwest of the state of Paraná (Brazil), were analyzed using molecular, biochemical and biological characteristics. Genotypic analysis using randomly amplified polymorphic DNA and simple sequence repeat-anchored polymerase chain reaction amplified profiles showed a large, genetically well-correlated group that contained the majority of the strains and a divergent group that included the PR-150 strain. For glycoconjugate composition, the PR-150 strain was different from the other strains considering the absence or presence of specific bands in aqueous or detergent phases. This strain was also totally different from the others in one out of the six parameters related to in vitro and in vivo biological behavior. We highlight the fact that the PR-150 was totally resistant to benznidazole. For the other biological parameters this strain was not totally distinct from the others, but it showed a peculiar behavior.