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Biomedical subjects

R Borojevic

Publications and source records attributed to R Borojevic.

102 records · Page 6Linked to original sources
PubMed1977

Chronic human schistosomiasis mansoni. Pathology of the Disse's space.

In chronic human schistosomiasis mansoni, the entire hepatic lobule is involved. The hepatovascular barrier is modified and shows hepatic sinusoids with hypertrophy and stratification of endothelium, basement membrane-like deposits, perisinusoidal fibrosis, diminution of hepatocellular microvilli and hepatocellular clasmatosis into the sinusoidal circulation. This transformation of an open circulation to a partly closed one may decrease the blood hepatocyte exchanges in schistosomiasis mansoni.

Cytoplasm↗
PubMed1976

[Active and passive fibr0us septa in severe hepatic fibrosis of man: demonstration of collagen hyperfibers by electron microscopy].

In the prospective study of the evolutive progonsis of severe human hepatic fibrosis, electron microscopic examination reveals within fibrous septa a peculiar form of collagen, the hyperfiber singularized by its large diameter. The conditions of the elaboration the elaboration of this type of fiber (inflammation and intense fibrogenesis) are the classic determinant factors of an unfavorable prognosis. The stages of its elaboration are not clear and allow two possible interpretations related to the remodeling stages of collagen.

Chronic Disease↗
PubMed1976

Schistosomal pigment in human and murine infections with Schistosoma mansoni.

Schistosomal pigment was studied by optical and electron microscopy in liver biopsies of patients with different clinical forms of schistosomiasis and in livers of mice experimentally infected with Schistosoma mansoni. Phagosomal and residual forms of the pigment are described. The quantity of pigment is low in subclinical and in hepatointestinal forms of schistosomiasis; it is high in young patients with the hepatosplenic form, and low in the old ones. The participation of the pigment in the pathogenesis of schistosomal lesions is discussed.

Adolescent↗
PubMed1976

Sensitization to Schistosoma mansoni antigen in uninfected children born to infected mothers.

Sensitization to Schistosoma mansoni antigen in uninfected children born to infected or uninfected mothers was studied by intradermal reaction. Immediate skin reaction, Arthus phenomenon, and delayed skin responses were noted. The skin response at 24 hr was positive in 48.1% of the uninfected children born to infected mothers, and in only 7.5% of uninfected (control) children born to uninfected mothers. Areas of skin reactions were also larger in the group born to infected mothers. Both of these differences were statistically significant. There were no significant variations according to age or sex. Only one immediate skin reaction was noted in each group, and Arthus phenomenon was never observed.

Antigens↗
PubMedDate not supplied

Interaction of human liver connective tissue cells, skin fibroblasts and smooth muscle cells with collagen gels.

Interactions of liver connective tissue cells, skin fibroblasts and smooth muscle cells with collagen gels in vitro were studied and compared. Liver connective tissue cells showed the lowest rate of migration into the gel and the highest speed of gel contraction, reflecting their high adhesiveness to the substrate as compared to the other cell lines studied. The analysis of their ultrastructural morphology showed that liver connective tissue cells and smooth muscle cells developed cytoskeletal and cytoplasmic organelle polarities, in response to the contact with gel surface. This polarity was lost when cells were embedded in the gel. Skin fibroblasts did not show this characteristic, neither on top nor in the gel. Although liver connective tissue cells have been recognized as analogous to smooth muscle cells, they represent a defined cell population, present in fibrotic livers, with specific behavior and with particular relationship to the extracellular matrix.

Cell Line↗
PubMedDate not supplied

Formation of spicules by sclerocytes from the freshwater sponge Ephydatia muelleri in short-term cultures in vitro.

Cells from the freshwater sponge Ephydatia muelleri were isolated by dissociating hatching gemmules. During the first 24 h the cells reaggregated, but the aggregates progressively disintegrated again to single cells, among which the spicule-forming sclerocytes were recognized. Such cultures were used to study spicule (megascleres) formation in vitro. The isolated sclerocytes formed the organic central axial filament onto which they deposited inorganic silicon. The size of the spicules (200 to 350 microns in length) as well as the rate of spicule formation (1 to 10 microns/h) under in vitro conditions were similar to the values measured in vivo. Immediately after completion of spicule formation, or even before, the sclerocyte could start formation of a new spicule; 5% of the cells were in the process of forming two spicules simultaneously. Cultivation of sclerocytes in the absence of silicon resulted in the formation of the axial filament only. We succeeded in maintaining the sclerocytes in a proliferating and spicule-forming state for up to 3 mo. These results demonstrate that the establishment of short-term cell cultures from E. muelleri is possible; however, future studies must be undertaken to identify the growth factors required for a permanent culture of sponge cells.

Animals↗
PubMedDate not supplied

Leishmania donovani: titration of antibodies to the fucose-mannose ligand as an aid in diagnosis and prognosis of visceral leishmaniasis.

The fucose-mannose ligand (FML) is a complex glycoprotein fraction present on promastigotes and amastigotes of Leishmania donovani. It participates in parasite interaction with host macrophages in a species-specific pattern. We have tested its use in immunodiagnosis of visceral leishmaniasis (VL) in a recent outbreak in Rio Grande do Norte, north-east Brazil. Enzyme-linked immunosorbent assay (ELISA) of low concentrations of FML in 462 sera showed 100% sensitivity and 96% specificity. The FML-ELISA identified patients with overt VL (P < 0.001, compared to normal sera). It could also identify inhabitants of the endemic area who had incipient or subclinical infection with potentially severe clinical disease: more than 20% of apparently healthy subjects with a positive ELISA for FML developed overt VL during the following 10 months. FML-ELISA reactivity decreased in all patients during treatment, and became negative after parasitological cure. No cross-reaction was observed in patients infected with other Leishmania species, nor in those with Chagas disease. Determination of antibody response to FML may be useful in diagnosis of VL and in identifying patients without overt disease but with a high risk of developing severe VL.

Animals↗
PubMedDate not supplied

Evolution of cell adhesion systems: evidence for Arg-Gly-Asp-mediated adhesion in the protozoan Neoparamoeba aestuarina.

Developmental processes in multicellular organisms require structural elements, such as adhesion molecules, to stabilize cells at functional positions. In vertebrates, a series of extracellular matrix proteins, e.g. fibronectin and laminin, are involved in cell adhesion. These proteins contain Arg-Gly-Asp [RGD] at their binding sites. Here we show that at concentrations above 2 mM the peptide GRGDSPK, comprising the tripeptide RGD (Arg-Gly-Asp), prevents the adhesiveness of cells of the marine amoeba Neoparamoeba aestuarina. In addition, elevated levels of GRGDSPK cause cells to alter their shapes from those with digitiform subpseudopodia to rounded cells with small lobed pseudopodia. These cells detach from the substratum. These results are specific for the RGD sequence, because incubation in GRGESPK solution at the same concentrations had no effect on cell attachment or structure. From these data we suggest that the structural adhesion molecules identified in vertebrates show amino acid homologies with those found in unicellular protozoa.

Amino Acid Sequence↗