Oogram studies in mice infected with Schistosoma mansoni and treated with dexamethasone.

Mice infected with about 90 cercariae of Schistosoma mansoni (LE strain) were treated during five consecutive days with dexamethasone (50 mg/Kg, subcutaneously), starting on the 42nd day of infection. Groups of five mice were then daily sacrificed from the first day after onset of treatment until the first day after. The perfusion of the portal system was performed and a piece of the intestine was processed for qualitative and quantitative oograms. This treatment carries to larger numbers of eggs in the tissues of treated mice, when compared with untreated groups. No changes were observed in the kinetics of oviposition, as all stages of viable eggs were observed in the tissues of treated and control mice. These data reinforce the hypothesis of a partial blockade of the egg excretion in immunosuppressed mice.

Schistosoma mansoni: the effect of dexamethasone on the cercaria-schistosomulum transformation, in vivo.

Treatment with dexamethasone (DMS) in the early phases of the experimental Schistosoma mansoni infection causes an indirect effect on the cercaria-schistosomulum transformation process. This is observed when naive albino mice are treated with that drug (50 mg/Kg, subcutaneously) and infected intraperitoneally 01 hour later with about 500 S. mansoni cercariae (LE strain). An inhibition in the host cell adhesion to the larvae, with a simultaneous delay in the cercaria-schistosomulum transformation, is observed. This effect is probably due to a blockade of the neutrophil migration to the peritoneal cavity of mice, by an impairment of the release of chemotactic substances. Such delay probably favors the killing of S. mansoni larvae, still in the transformation process, by the vertebrate host defenses, as the complement system.

[Comparative histopathologic study of the skin test in dogs from an endemic area of tegumentary leishmaniasis, using 2 antigens: Leishvacin and P10.000G]. / Estudo histopatológico comparativo do teste cutâneo em cães de área endêmica de leishmaniose tegumentar, utilizando dois antígenos: Leishvacin e o P10.000G.

The Montenegro skin test is widely used as a diagnostic method for American cutaneous leishmaniasis (ACL). However, there is little information about the histological changes that occur after administration of the antigen, especially in dogs. Two intradermal reactions were used in mongrel dogs during a clinical and epidemiological study as a diagnostic method for canine cutaneous leishmaniasis at Virginópolis, Minas Gerais, Brazil. Leishvacin and P10,000G were used as antigens. The inflammatory reaction was more intense and diffuse in dogs tested with P10,000G than Leishvacin.

Kinetics of the pulmonary phase of Schistosoma mansoni in mice treated with dexamethasone.

In the experimental schistosomiasis mansoni glucocorticoids cause a reduction in the worm burden when administered in the week of infection or, the longest, at the next week. In order to determinate the probable(s) site(s) of reduction of the worm burden, mice were infected with cercariae of LE strain of S. mansoni and dexamethasone was administered daily (50 mg/kg, subcutaneously) starting 1 hour before infection until the eighth day. Mice were sacrificed daily starting on the third day after infection until the ninth day, and schistosomula from lungs were collected. Six weeks after infection, the remaining mice were sacrificed and perfused for adult worm recovery. Analysis of the results showed that the non-treated mice presented larger numbers of lung larvae than the treated ones, and this difference was also found later in the worm burden in the portal system. This difference may reflect the early death of larvae in treated animals, before or after reaching the lungs.