Histopathological alterations induced by non-viable cells and biochemical fractions from Paracoccidioides brasiliensis in mice

Non-viable cells and biochemical fractions from Paracoccidioides brasiliens were obtained for experimental inoculation in mice and posterior histopatological analysis. Dead total fungus, total fungus disrupted by sonorous waves, lipids of the fungus, supernatant of the lipid purification, integral and disrupted fungus free of lipids were obtained. The six preparations arised from masses of lyophilized yeasts of a recent isolate of P. brasiliensis (strain JT-1) and from a "Pool" equitably constituted by four strains maintained in laboratory for a long time (SN, 2, 18 and 192). Different doses of the 12 preparations were intraperitonially inoculated and histopathological analysis were done 30 days later. This analysis showed that all the inoculated preparations gave origin to inflamatory foci, except the one designated "supernatant of lipid purification". The alterations were detected exclusively in the liver of the animals and occurred from the smallest dose tested (1 mg), with exception of the lipids of the fungus, where the foci appeared only from a 3 mg dose onwards. No difference in the capacity of inducing histopathological alterations was found between the preparations obtained from the recent isolate (JT-1) and from the older ones ("Pool"). On the other hand, an increase of the number of inflammatory foci in function of the inoculated dose was observed

A toxoid prepared from cholera toxin by iodination

A cholera toxoid was prepared by iodinating purified cholera toxin having an activity of 25 Limit of blueing (Lb) doses/l ug with 0.8 umol of iodine monochloride per mg toxin, and the residual lesion capacity was tested in mice. The Blueing Dose (BD) test was strongly positive for the native toxin, and co0mpletely abolished in the iodinated toxoid when tested at up to 25 times one Lb dose. The dermal microscopic lesions with intradermal doses of 1 ug virulent toxin presented intense leucocyte infiltration, proteinaceous edema and active hypertemia, whereas none of these effects was observed with the same amount of toxoid. To determine antigenicity, two groups of micereceived toxin or toxoid, 8.5 ug adsorbed to aluminum hydroxide, followed by a booster of 17 ug in saline 21 days later. Measurement of antibodies by ELISA at day 28 indicated that the toxoid was 2.5 times more antigenic than the toxin. These data show iodination converts cholera toxin to an effective toxoid

Efeito da timectomia neonatal na esquistossomose mansoni experimental. / Effect of neonatal thymectomy in experimental schistosomiasis mansoni

Camundongos albinos recem-nascidos foram submetidos a timectomia e infectados 30 dias apos com 60 cercarias de Shistosoma mansoni. Foi incluido no experimento um grupo controle constituido de animais timectomizados, nao infectados, nao timectomizados infectados e nao timectomizados nao infectados. Foi realizado estudo histopatologico minucioso dos animais antes do inicio da oviposicao e sete semanas apos a infeccao. Os animais timectomizados e infectados mostraram quadro caracteristico devido a deplecao dos linfocitos T, com marcada diminuicao do desenvolvimento do granuloma e escasso exsudato inflamatorio em torno dos ovos. Lesoes graves foram observadas no figado, em animais sacrificados sete semanas apos a infeccao e sem qualquer reacao inflamatoria. Foram muito escassos os fenomenos exsudativos intra e extralobulares, no figado. Os fenomenos necroticos degenerativos dos hepatocitos foram considerados como sendo devidos a infeccao esquistossomotica, em animais com deplecao de linfocitos T