Mitogenicity of autolysates ofTrypanosoma congolense

Summary Autolysates ofTrypanosoma congolense, in subcytotoxic amounts, were found to be highly mitogenic in vitro for the spleen cells of normal mice. Significant amounts of [³H]-thymidine were also incorporated by the responding spleen cells of nu/nu (athymic) mice. In contrast, the spleen cells of cyclophosphamide-treated mice were unresponsive. The findings suggest that a potent B-cell-mitogen is generated by the autolysingT. congolense organism.Acknowledgments. This investigation was supported by the International Development Research Centre, Canada.     

The generation and identification of the hemolysin of Trypanosoma congolense

Summary The hemolytic activity of Trypanosoma congolense appears to be due to the presence of free fatty acids generated by the action of phospholipase A on endogenous phosphatidyl choline. Some lysolecithin also contributes to the lytic activity. Trypanosoma lewisi, being devoid of phospholipase A does not generate free fatty acids and is therefore non-hemolytic.This research was supported by the International Development Research Center.     

The generation of toxic activity fromTrypanosoma congolense

Summary Trypanosoma congolense organisms, on incubation at 20°C for 91/2h, were found to generate phospholipaselike activity which was capable of mediating lysis of both nucleated cells and erythrocytes as well as an acute inflammatory response on intradermal inoculation.Acknowledgments. This investigation was supported by the International Development Research Centre.     

The generation of toxic activity from trypanosoma congolense.

Trypanosoma congolense organism, on incubation at 20 degrees C for 91/2h, were found to generate phospholipase like activity which was capable of mediating lysis of both nucleated cells and erythrocytes as well as acute inflammatory response on intradermal inoculation.     

Effect of actinomycin D on Trypanosoma cruzi

Viable metacyclic forms of T. cruzi, Y strain, treated with an adequate dose of actinomycin D (50 micrograms Act-D/ml/10(7) parasites/ml for 72 h at 28 degrees C) showed the following properties: 1) they lost their ability to replicate in culture medium, in blood and in tissues of normal mice and were no longer able to incorporate tritiated thymidine; 2) they could not penetrate into Vero cells and could not replicate inside normal macrophages; 3) they retained their immunogenicity and the ability to protect mice against a virulent infection; 4) they did not induce histological lesions as described in chronic experimental Chagas' disease.     

Biological observation in quantitative tests ofNippostrongylus brasiliensis acting as vector ofTrypanosoma brucei orTrypanosoma congolense

Résumé Des rats ont été infectés par des Trypanosomes soit directement soit par l'intermédiaire deNipponostrongylus, Nématode parasite. Le degré de la parasitémie produite dans le premier cas fut à peu près aussi élevé que dans le second. Des différences apparurent dans le poids de la rate et l'altération des leucocytes.     

Trypanosoma cruzi: metabolic labeling of trypomastigote sialoglycolipids

Summary Trypomastigote forms (infective) ofTrypanosoma cruzi incorporate (³H)-palmitic acid and D-(³H)-galactose into glycolipids. Palmitic acid-labeled acidic glycolipids were partially hydrolyzed with neuraminidase. The labeling of these compounds when the intact cell surface was labeled with galactose oxidase plus NaB³H₄ indicates the membrane location of the sialoglycolipids.This investigation received financial support from SECYT and CONICET to RML; CNPq, FINEP, and UNDP/World Bank/ WHOSSpecial Programme for Research and Training in Tropical Diseases to WC; and FAPESP to BZ and WC. ASC is a fellow from FAPESP.     

Trypanosoma cruzi: metabolic labeling of trypomastigote sialoglycolipids

Trypomastigote forms (infective) of Trypanosoma cruzi incorporate (3H)-palmitic acid and D-(3H)-galactose into glycolipids. Palmitic acid-labeled acidic glycolipids were partially hydrolyzed with neuraminidase. The labeling of these compounds when the intact cell surface was labeled with galactose oxidase plus NaB3H4 indicates the membrane location of the sialoglycolipids.     

Hydrogen peroxide generation in Trypanosoma cruzi.

Homogenates from T. cruzi epimastigotes produced 3.4 pmoles H2O2/min 10(6) cells, as detected by the cytochrome c peroxidase assay. Addition of NADH or NADPH increased H2O2 production by a factor of 3 and 5, respectively. When supplemented with NADH and NADPH, the mitochondrial, microsomal and supernatant fractions produced H2O2, the soluble fraction and the mitochondrial membranes being apparently the main generators of H2O2. The epimastigote homogenates showed cyanide-sensitive superoxide dismutase activity, equivalent to 0.28 microgram bovine superoxide dismutase per mg homogenate protein.     

Identification of Trypanosoma theileri as a contaminant in primary cultures of bovine retina

T. theileri has been isolated from primary cultures of bovine retina and subcultered successfully for 2 passages in sub-confluent cultures. When cultures reached confluency no trypomastigotes or epimastigotes could be detected and attempts to recover trypanosomes from these cultures were unsuccessful. The presence of intracellular forms could not formally be excluded.