Experimental Chagas' disease in rhesus monkeys. I. Clinical, parasitological, hematological and anatomo-pathological studies in the acute and indeterminate phase of the disease.

Rhesus monkeys (Macaca mulatta) were infected subcutaneously with 1.0 x 10(4) to 1.5 x 10(4) metacyclic trypomastigotes of Trypanosoma cruzi (Colombian strain). Parasitological and immunological parameters were evaluated in these animals for periods of 1 month to over 3 years. A chagoma was observed between the 3rd and the 13th day after infection (a.i.) and patent parasitaemia between the 13th and 59th day a.i.. Thereafter, parasites were demonstrated only by haemoculture and/or xenodiagnosis. Circulating specific IgM and IgG antibodies were observed as early as in the 2nd week a.i. IgG levels persisted until the end of the experiment, but IgM antibodies were detectable nine months a.i. Haematological alterations comprised leucocytosis and lymphocytosis. Electrocardiographic alterations were minor and transient, similar to those observed in non-lethal human acute Chagas' myocarditis. Myocarditis and myositis, characterized by multiple foci of lympho-histiocyte inflammatory infiltrate, were present in monkeys sacrificed on the 41st, 70th and 76th day but not in the animal sacrificed 3 years and 3 months a. i.. The results suggest that Chagas' disease in rhesus monkeys reproduces the acute and indeterminate phases of human Chagas' disease.

Trypanosoma cruzi: experimental Chagas' disease in rhesus monkeys. II. Ultrastructural and cytochemical studies of peroxidase and acid phosphatase activities.

Ultrastructural and cytochemical studies of peroxidase and acid phosphatase were performed in skin, lymph node and heart muscle tissue of rhesus monkeys with experimental Chagas' disease. At the site of inoculation there was a proliferative reaction with the presence of immature macrophages revealed by peroxidase technique. At the lymph node a diffuse inflammatory exudate with mononuclear cells, fibroblasts and immature activated macrophages reproduces the human pattern of acute Chagas' disease inflammatory lesions. The heart muscle cells present different degrees of degenerative alterations and a striking increase in the number of lysosomal profiles that exhibit acid hydrolase reaction product. A strong inflammatory reaction was present due to lymphocytic infiltrate or due to eosinophil granulocytes associated to ruptured cells. The present study provides some experimental evidences that the monkey model could be used as a reliable model to characterize histopathological alterations of the human disease.

A test for the evaluation of ingestion by neutrophils.

A rapid, simple and inexpensive technique was developed to evaluate particle ingestion by neutrophils (PMNs) and alternatively investigate the activity of the complement system. Whole blood specimens, obtained in EDTA, were mixed with a suspension of activated Baker's yeast in minimal volumes (3 and 1 drops of each, respectively). The mixture was incubated at 37 degrees C for 1 h and centrifuged at 200 g for 5 min. The sediment was resuspended in FBS and blood films were stained with Giemsa. Two hundred PMNs/film were counted and the percentage of phagocytizing cells and the mean number of ingested particles per cell were determined. Samples from 11 male and 15 female subjects showed mean rates of 80.0 +/- 10.8 (SD) and 83.3 +/- 5.8 of PMNs with phagocytic vacuoles containing 2.9 +/- 0.5 and 3.2 +/- 0.7 ingested particles/cell, respectively. There were no statistically significant differences between sexes.

Reavaliacao da tecnica de imunodifusao radial para identificacao de amostras toxinogenicas de Corynebacterium diphtheriae. / Reevaluation of radial immunodiffusion technic for the identification of toxinogenic samples of Corynebacterium diphtheriae

Os autores descrevem e avaliam modificacao da tecnica de imunodifusao radial, proposta inicialmento por Ouchterlony, para pesquisa de toxinogenicidade de C. diphtheriae. A modificacao proposta foi comparada com o metodo de Elek, utilizando-se 71 amostras de microrganismos recem isolados com diagnostico presuntivo de bacilo difterico e uma amostra padrao. O metodo sugerido demonstrou maior sensibilidade sem aparente perda da especificidade, sendo de facil execucao e interpretacao e, ainda, mais economico