Life cycle of Trypanosoma cruzi (y strain) in mice

Since 1958, we have studied experimental Chagas' disease (CD) by subcutaneous inoculation of 1,000 blood forms of Trypanosoma cruzi (Y strain) in Balb/C. mice. Evolution of parasitemia remained constant, beginning on the 5th and 6th day of the disease, increasing progressively, achieving a maximum on about the 30th day. After another month, only a few forms were present, and they disappeared from the circulation after the third month, as determined from direct examination of slides and the use of a Neubauer Counting Chamber. These events coincided with the appearance of amastigote nests in the tissues (especially the cardiac ones), starting the first week, and following the Gauss parasitemia curve, but they were not in parallel until the chronic stage. In 1997, we began to note the following changes: Parasites appeared in the circulation during the first week and disappeared starting on the 7th day, and there was a coincident absence of the amastigote nests in the tissues. A careful study verified that young forms in the evolutionary cycle of T. cruzi (epi + amastigotes) began to appear alongside the trypomastigotes in the circulation on the 5th and 7th post-inoculation day. At the same time, rounded, oval, and spindle shapes were seen circulating through the capillaries and sinusoids of the tissues, principally of the hematopoietic organs. Stasis occurs because the diameter of the circulating parasites is greater than the vessels, and this makes them more visible. Examination of the sternal bone marrow revealed young cells with elongated forms and others truncated in the shape of a "C" occupying the internal surface of the blood cells that had empty central portions (erythrocytes?). We hypothesize that there could be a loss of virulence or mutation of the Y strain of Trypanosoma cruzi

Experimental toxoplasmosis, and immunosupression (parasite evaluation and histological alterations)

Com a finalidade de estudar a acao das drogas imunossupressoras nas parasitoses, estudamos a Cyclosporina A e Cortisona na toxoplasmose experimental, utilizando uma cepa altamente virulenta do Toxoplasma gondii (cepa RH). Os animais foram divididos em dois lotes: controle e imunodeprimidos, sendo avaliados pela pesquisa da parasitemia e parasitismo do exsudato peritoneal, e parasitismo do coracao, figado, baco, pancreas, intestino, rim, supra renal, cerebro, cerebelo, medula espinhal e globo ocular sendo sacrificados diariamente dois animais de cada grupo. O parasitismo do exsudato peritoneal foi dez vezes maior que a parasitemia do segundo dia, foram encontradas manchas avermelhadas e do quarto dia, necroses focais com areas de amolecimento e liquefacao da massa encefalica salpicadas no tecido nervoso...

Hypovolemic hemorrhagic shock (an experimental study)

Com o intuito de estudar os fenomenos naturais de defesa contra as hemorragias traumaticas, foram estudados 20 camundongos examinando-se histologicamente algumas de suas grandes veias em caso de sangria, sangria+hemodiluicao e controles, apos fixacao em formol...