Trypanosoma Cruzi Amastigotes Research Articles

Immunofluorescence as an adjunct to the histopathologic diagnosis of Chagas' disease

We have developed a new indirect immunofluorescence procedure for identifying Trypanosoma cruzi amastigotes in sections of Formalin-fixed, paraffin-embedded tissue pretreated with a 0.25% trypsin solution to enhance immunofluorescence. In sections of human and mouse myocardia infected with T. cruzi and stained by this procedure, both intact amastigotes and phagocytosed amorphous antigen were intensely fluorescent and easily detected; nonspecific background fluorescence was absent or minimal. No staining occurred in similarly treated sections of Formalin-fixed, paraffin-embedded tissue that contained Histoplasma capsulatum var. capsulatum, Toxoplasma gondii, or Leishmania donovani to control specificity. Because pathology laboratories usually receive Formalin-fixed tissues for evaluation, this rapid and reliable procedure can be used to extend the diagnostic capability of conventional histopathology.

Trypanosoma cruzi: Adrenergic modulation of cyclic AMP role in proliferation and differentiation of amastigotes in Vitro

Trypanosoma cruzi amastigotes, obtained from the supernatant of J774G-8 macrophage cultures infected with Y strain trypomastigotes, proliferated and differentiated into epimastigotes in Warren medium at 28–29 C. The basal level of adenosine 3′:5′-monophosphate (cAMP) in recently harvested amastigotes was 0.12 pmole/10 7 cells, which could be increased in a dose-dependent manner to 0.62 pmole/10 7 cells with 1 m M of the adrenergic ligand isoproterenol plus 0.5 m M isobutyl methylxanthine. Isoproterenol inhibited [ 3H]thymidine incorporation into amastigote DNA, as well as the proliferation of amastigotes and newly transformed epimastigotes. Because dibutyryl cAMP had the same effect as isoproterenol on the cells, the experimental results suggest a role for cAMP, modulated by adrenergic ligands, in the control of proliferation and differentiation of amastigotes.

The neuromuscular pathology of experimental Chagas' disease

In this work, we describe skeletal muscle, neuromuscular junction, nerve and spinal cord lesions in the mouse model system of Chagas' disease. Myositis was a common finding and Trypanosoma cruzi amastigote nests were frequently found in the muscle fibers. Angular atrophy, targetoid fibers, groups of atrophic fibers, fibrosis, myofiber necrosis and phagocytosis of cellular debris were also observed. The neuromuscular junction studies showed degeneration of intramuscular nerve fibers, swelling and distortion of nerve endings and multiple ramifications on the same muscle fiber. Collateral, terminal and ultraterminal axonal sprouts were also present. Inflammatory neuropathy was seen in all of the infected mice. Demyelination, axonal degeneration, remyelination and axonal regeneration were observed in the transverse sections. There was an average reduction of 29% in the total number of myelin fibers. The teasing of single myelin fibers showed segmental and paranodal demyelination and remyelination more frequently than axonal degeneration and regeneration. The lumbar spinal cords presented inflammatory cell infiltration associated with tissue destruction. Amastigote nests were found in 3 out of the 8 infected mice studied. There was a mean loss of 21% of the large cytoneurons of the anterior horn of the lumbar spinal cord.

Congenital Chagas disease: immunocytochemical evaluation of parasitism in tissues of the macerated fetus

O método imunocitoquímico de peroxidase anti-peroxídase é aplicado, pela primeira vez, em tecidos de natimorto macerado de II-III graus para coloração específica de amastigotas do Trypanosoma cruzi, em caso de doença de Chagas congênita. Os resultados mostram que o encontro de ninhos de amastigotas é muito facilitado pelo método, mesmo em tecidos autolisados, onde a morfologia dos parasitas geralmente se mostra muito alterada; o método é recomendável, também nestes casos, para a avaliação mais precisa da intensidade do parasitismo.

Cryostat sections with tissue amastigotes of Trypanosoma cruzi as a substrate for Chagas' disease serology

Sera from 30 chronic chagasic patients together with 52 control samples (34 with other pathological conditions and 18 from normal individuals) were titrated by the indirect immunofluorescent technique (IFA) on Trypanosoma cruzi amastigotes. Acetone-fixed cryostat sections of skeletal muscle of Rockland mice 10 days post-infection with the RA isolate of T. cruzi were used as substrate. Results were compared with titres obtained by conventional IFA on epimastigotes. All 52 control sera had amastigote litres ⩽2 double dilutions (dd) as compared with epimastigote values. Out of the 30 chagasic samples, differences were ⩾4 dd (⩾1 log) for 22, 3 dd for 5 and ⩽2 dd for the remaining 3, when comparing amastigote and epimastigote titres. These results show that the use of amastigotes in cryostat sections of infected tissue for performing Chagas' serology is a simple, adequate and sensitive method.