Retrospective study on dengue fatal cases.

Immunohistochemical procedure (avidin biotin peroxidase complex) was applied in formalin-fixed and paraffin-embedded tissues obtained from 5 fatal cases of dengue infection associated with encephalopathy. Dengue virus antigen was demonstrated in the cytoplasm of phagocytic mononuclear cells from liver, spleen, and lung. Moreover, dengue viral antigens were here, to our knowledge, first demonstrated in the central nervous system (CNS) and numerous immunolabelled cells were found in brain sections from 3 cases. Extended immunohistochemical studies carried out in 1 case showed virus-positive cells mostly located within Virchow Robin space of medium size and small veins, infiltrating the white and grey matter, and often situated close to neurons displaying apparent cytopathic features. Furthermore, immunostaining for CD68 antigens demonstrated that most CD68+ macrophages and dengue antigen-positive cells share similar morphology and localization, suggesting a unique identity for at least part of these cells. Since in dengue fever, virus replicates mostly in cells of macrophage lineage, our results seem to indicate that infiltration of virus-infected macrophages could be one of the pathways by which viruses enter the brain in dengue encephalitis. Whether bone marrow-derived infected macrophages and viral-free particles induce CSN lesions through immune, metabolic, and/or direct viral-induced mechanisms will be essential to better understand the pathogenesis and provide new therapeutic strategies for dengue-associated encephalitis. As the evidence of tissue damage was nonspecific, the detection of virus antigen by immunoperoxidase technique appeared to be highly reliable for dengue diagnosis.

Gradient chamber. A new method for migratory fractionation of inflammatory response in vivo.

A new and simple method to study the inflammatory process in vivo using a diffusion-migration chamber is described. The influx of inflammatory elements into chambers was studied by light and electron microscopy. This gradient chamber (GC) was developed by substituting one of the filters of the classic diffusion chamber by a polyvinyl sponge cylinder. In the implanted chambers this plastic framework acts as a tridimensional gradient, through which the acute and chronic inflammatory processes migrate with different speeds and are thus divided into two distinct and widely separated waves. By delaying the overlapping of the first wave by the second, this bioassay allows a longer time for observation of the cell-matrix or cell-matrix-graft interaction during the first inflammatory wave and permits studies by methods such as immunocytochemistry, histochemistry or biochemical analysis.

[Evaluation of the incidence and toxicity of samples of Bacillus cereus in various classes of foods sold and consumed in the State of Rio de Janeiro]. / Avaliacão da incidência e da toxicidade de amostras de Bacillus cereus em diferentes classes de alimentos comercializados e consumidos no Estado do Rio de Janeiro.

One hundred and fourteen strains of Bacillus cereus were isolated during presumptive plate-counts from 18 groups of industrialized, non-industrialized, crude or cooked food, belonging to 10 separate classes. Specific presumptive counts ranged from 10(2) to 6 X 10(3)/g or ml. Among these isolates, 13 strains were derived from 3 outbreaks of food poisoning (involving a minimum of 57 people), as determined by the assayed bacteriological quality of the ingested foods. As an adopted procedure to correlate toxicity and ability to promote illness in man, culture fluids of all strains were assayed to determine their ability to increase vascular permeability (APC) to cause necrosis in rabbits skin and to kill albino mice. APC was positive in 86.85% of the 114 strains, death of albino mice occurred in 65.79% and a combination of APC and death was observed in 59.65%. APC plus necrosis, or only necrosis, occurred with 34.21% of the culture fluids. Death, APC and death with or without necrosis, were demonstrated in the strains implicated with illness. This confirmed the known individuality of action exhibited by certain B. cereus food-borne toxigenic factors. The low presumptive counts of this bacterium in the order of 10(2)-10(3)/g or ml found in food, implicated or not with illness, suggests that the recommended number of B. cereus per g or ml of food sample should be reevaluated in our country. Furthermore, a wider range of food should be brought under bacteriological sanitary control for this species.

Parasitismo do endometrio em camundongos infectados com Trypanosoma cruzi: estudo histocitopatologico - Nota previa. / Endometrial parasitism in Trypanosoma cruzi infected mice: histo-cytopathologic study - Preliminary report

Estudando por metodos histocitopatologicos o endometrio de dez camundongos nao prenhes infectados com cepa virulenta de T. cruzi em fase aguda da infeccao, foi possivel evidenciar a presenca de formas amastigotas no estroma endometrial de sete animais

Local effects of silica on tumor growth inhibition. A histological study.

The subcutaneous implant of a fibrosarcoma covered with silica, in rats, resulted in a temporary retardation of tumor growth. The histological study demonstrated that the silica provoked, within and at the periphery of the tumor, inflammatory foci which altered the composition of the fundamental substance and which promoted the accumulation of principally macrophages in the interior as well as on the surface of the tumoral mass. Besides the macrophages of the host, a number of tumor cells do also phagocyte silica crystals, leading to destruction of all those cells. The authors are of the opinion that the local modifications provoked by silica, could have interfered in the adaptation of the tumor with its nutrient stroma. Of these modifications, the stroma sclerosis seems to be the most effective in the inhibition of tumor growth. Some correlations were suggested between the here described results and those obtained by other workers who have used other inflammatory agents of different nature.

Growth inhibition of sarcoma 180 induced by silica and talc.

In applying amorphous silica and talc in the site of solid Sarcoma 180 implants, the authors found a suppression and delay of tumor growth which was proveked by peritumoral foreign-body granulomas. Correlating these findings which those experiments which resulted in granulomas of hypersensitivity type, it may be suggested that any kind of peritumoral chronic inflammation enables an anti-tumor effect.