Detection of Toxoplasma gondii DNA in Brazilian oysters (Crassostrea rhizophorae).

The aim of this study was to detect evidence of Toxoplasma gondii using polymerase chain reaction (PCR)-based techniques in oysters (Crassostrea rhizophorae) obtained from the southern coastal region of Bahia, Brazil. A total of 624 oysters were collected, and the gills and digestive glands were dissected. Each tissue sample was separated into pools containing tissues (of the same type) from three animals, leading to a total of 416 experimental samples for analysis (208 samples each from the gills and digestive glands). Molecular analysis using PCR-based detection of the T. gondii AF 146527 repetitive fragment yielded negative results for all samples. However, when nested-PCR was used for detection of the T. gondii SAG-1 gene, 17 samples were positive, with the gills being the tissue with maximal detection of the parasite. These positive results were confirmed by sample sequencing. It is therefore suggested that C. rhizophorae oysters are capable of filtering and retaining T. gondii oocysts in their tissue. This represents a risk to public health because they are traditionally ingested in natura.

Host granulomatous response in schistosomiasis mansoni. Antibody and cell-mediated damage of parasite eggs in vitro.

In chronic schistosomiasis mansoni the major pathologic lesions are granulomas surrounding eggs deposited in host tissues. Parasite ova release antigenic material that sensitize the host, resulting in the development of delayed-type hypersensitivity granulomas. The objectives of the present study were to assess the ability of components of the host granulomatous response to induce biochemical and biologic alterations in eggs in vitro, and to correlate these with the capacity of ova to induce granulomas in vivo. An assay of egg tricarboxylic acid cycle activity was developed by use of 2-[14C]acetate as substrate and measurement of accumulation of released 14CO2. Addition of human granulocytes (96% neutrophils, 4% eosinophils) to eggs (cell/egg ratio 1,000:1) and heat-inactivated normal human serum reduced predicted egg 14CO2 generation by 15.6 +/- 3.0%. This effect was greater in the presence of sera of subjects with schistosomiasis (25.6 +/- 2.8% reduction) or when complement was present (24.4 +/- 4.0%). Autologous eosinophils and neutrophils were equally effective in decreasing egg 2-[14C]acetate metabolism (25.6 and 21.4% reductions, respectively). Since the biological role of schistosome eggs relates to their ability to hatch and produce miracidia, we evaluated the effect of granulocytes and sera on this function. The hatching rate of eggs incubated with normal serum was 52.8 +/- 3.3 miracidia/100 eggs; this value decreased to 37.0 +/- 2.6 when granulocytes were added (P less than 0.01). Granulocytes plus antibody- or complement-containing sera led to hatching rates of 23 and 20 miracidia/100 eggs. When ova were pre-incubated with granulocytes and various sera and injected into mice, the areas of egg-induced pulmonary granulomas measured 8 d later were reduced 32 to 45% as compared with lesions elicited by parasite eggs not exposed to granulocytes. Exposure of antigen-coated Sepharose beads to granulocytes and immune serum before injection into mice also led to a reduction in granuloma formation as compared with beads pre-incubated with serum alone. These data indicate that granulocytes in conjunction with antibodies and complement inflict biologically relevant toxic effects on eggs that are manifest in vivo by a decreased ability to elicit granulomas.

Carcinosarcoma (malignant mixed müllerian (mesodermal) tumor) of the female genital tract: immunohistochemical and ultrastructural analysis of 28 cases.

In an attempt to clarify the histogenesis of carcinosarcoma (malignant mixed müllerian tumor) of the female genital tract, 20 uterine and eight ovarian tumors were studied by light microscopy, transmission electron microscopy, and immunohistochemistry. Cytokeratins (MAK-6 and AE1:AE3) and epithelial membrane antigen were detected in the epithelial component of all tumors and in the stromal component of 15 cases (55%). Vimentin was detected in the stromal component of all cases and was focally positive in the epithelial component of 18 cases (69%). Tumors showing rhabdomyosarcomatous or chondrosarcomatous differentiation were positive for myoglobin and S-100 protein, respectively. At the ultrastructural level epithelial cells were observed in tight clusters (usually surrounded by a basal lamina), in loose aggregates, and singly (sometimes spindle shaped), and were surrounded by cells displaying variable differentiation. The closest examples of "hybrid" epithelial/stromal cells were those with a prominent rough endoplasmic reticulum, cytoplasmic projections, poorly formed intercellular junctions, and an incomplete basal lamina. The observations support the view that carcinosarcomas of the female genital tract could represent examples of biphasic (metaplastic) carcinomas.

Evolution of schistosomal hepatic vascular lesions after specific chemotherapy.

Mice infected with 30 cercariae of Schistosoma mansoni showed extensive destruction, obstruction, and distortion of the intrahepatic portal vein system 10 weeks after exposure. One month after curative treatment for schistosomiasis, these lesions had considerably regressed. The vascular pattern was almost normal by 2 months and completely normal by 6 months following treatment. The techniques used to study vascular changes included plastic casting, injection of colored gelatin, and conventional histopathologic methods. Main transformations observed after treatment were shrinkage of periovular granulomas and formation of new vascular channels around them, which restored the continuity of the portal vein system. Shrunken granulomas remained avascular.

Cytomorphology of a mixed pigmented/nonpigmented pleomorphic adenoma of the ciliary body: a diagnostic pitfall in the evaluation of intraocular tumors.

Intraoperative cytology is an alternative and sometimes preferred method to frozen section in the rapid evaluation of surgical biopsies. This report describes the cytological, histological, and immunohistochemical features of a case of mixed pigmented/nonpigmented pleomorphic adenoma of the ciliary body with clinical and morphological features reminiscent of malignant melanoma. The characteristic cyto-histomorphology of this unusual tumor and its distinguishing features from malignant melanoma are discussed.

Enhanced helminthotoxic capacity of eosinophils from patients with eosinophilia.

To determine whether eosinophils from patients with eosinophilia have an enhanced capacity to kill parasites, we compared purified eosinophils (mean purity, 89 per cent) from 30 patients with various degrees of eosinophilia and with or without infection with Schistosoma mansoni for the capacity to kill schistosomula, the larval stage of S. mansoni, in vitro. There was a significant correlation between peripheral eosinophil count and antibody-dependent, eosinophil-mediated death of parasites after 40 hours of culture (P < 0.0001). Antibody-dependent adherence of eosinophils, measured after two hours of incubation, also correlated with the capacity of the eosinophils to kill the parasites. The correlation between the killing capacity of eosinophils and their peripheral-blood count was observed in patients both with and without S. mansoni infection. We suggest that eosinophilia involves not only a quantitative change in eosinophil numbers but also a qualitative change in functional capacity that renders circulating eosinophils more effective in resisting parasitic infections.