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Biomedical subjects

N Sorgente

Publications and source records attributed to N Sorgente.

8 recordsLinked to original sources
PubMed1992

Ultrastructures of the glial epiretinal membrane induced by activated macrophages.

A rabbit model of glial epiretinal membrane was established following the injection of activated macrophages into the vitreous. The membrane was composed entirely of cells with glial characteristics, ie, abundant intermediate filaments, microvilli, junctional complexes and basement membranes. The extracellular matrix of the mature membranes contained collagen fibrils of 10 to 15 and 20 to 25 nm in diameter. Fusiform densities were seen adjacent to the cell membrane and cells with indented nuclei were found in thick membranes. These observations demonstrate that glial cells in epiretinal membranes may synthesize collagen and possess myofibroblast-like properties.

Animals↗
PubMed1977

Proteolysis associated with normal, carcinogen-treated, and transformed rat liver epithelial cells.

A method was developed to distinguish between cell surface-associated and released proteolytic activity. The approach utilizes 125I-labeled protein substrate covalently linked to modified latex beads. These beads are either rolled over the surface of cells grown in culture or next to the cells. Using this method we have studied normal, carcinogen-treated and spontaneously transformed rat liver epithelial cells. Transformed cells always released greater amounts of radioactivity than carcinogen-treated or normal hepatocytes when the beads were presented next to the cells, indicating an enhanced release of proteolytic enzymes. When the substrate was in contact with the viable cell surfaces both the carcinogen-treated and transformed cells released more radioactivity from the beads' surface than the tissue culture-adapted normal cells. This enhanced proteolytic cleavage indicated that there is an altered surface topology or an increased surface-associated enzyme activity on both the carcinogen-treated and transformed cells.

4-Nitroquinoline-1-oxide↗
PubMed1975

The resistance of certain tissues to invasion. II. Evidence for extractable factors in cartilage which inhibit invasion by vascularized mesenchyme.

If hyaline cartilage is explanted to the chick chorioallantoic membrane, it resists invasion by vascularized mesenchyme of the host. This resistance is diminished if the tissue is extracted with relatively low concentrations (1.0 M) of guanidine HCl. The extracts contain antiproteolytic activity. This molarity of guanidine HCl extracts only small amounts of the major structural components of cartilage extracellular matrix. It, therefore, seems reasonable to suggest that hyaline cartilage is both avascular and resistant to invasion because it contains extractable inhibitors of invasion, perhaps in the form of proteinase inhibitors.

Allantois↗
PubMed1975

The resistance of certain tissues to invasion. III. Cartilage extracts inhibit the growth of fibroblasts and endothelial cells in culture.

Extracts of bovine dermis and cartilage inhibit the growth of bovine endothelial cells more than that of most of the fibroblast types tested. Extracts of cartilage, a tissue rather resistant to invasion, inhibit the growth of endothelial cells more than extracts of dermis do. Since such extracts contain antiproteolytic activity, it is suggested that the inhibition of cell growth they induce is effected by protease inhibitors native to connective tissues.

Animals↗
PubMed1975

Lysozyme in calcifying tissues.

Lysozyme, present in several connective tissues, is synthesized in cartilage by chondrocytes and immediately secreted into the extracellular matrix, where it is bound in the territorial (lacunar) matrix and along collagen fibers. In the epiphyseal growth plate, lysozyme levels increase toward the cartilage-bone junction, but cartilage lysozyme seems to be bound or inactivated by an inhibitor. Parathyroid extract injections decrease bone lysozyme levels. Cartilage lysozyme levels are low in rickets, while vitamin D increases it in both cartilage and aorta, suggesting an association between lysozyme and the calcification process. Although it is cationic and forms salt-like complexes with cartilage proteoglycans and chondroitin sulfate in vitro, lysozyme does not seem to be bound to proteoglycans in the native tissue. Proteoglycans in cartilage exist in a monomeric and aggregated form. Aggregation occurs by an interaction of monomers with hyaluronic acid and spedific link proteins. Aggregated proteoglycans inhibit mineral accretion in vitro. Mammalian cartilage lysozyme but not hen egg white lysozyme seems to inactivate this inhibitory capacity of aggregated proteoglycans, which is probably due to an interaction with hyaluronic acid resulting in a disaggregation. Therefore, we hypothesize that cartilage lysozyme plays an important role in the regulation and initiation of cartilage calcification.

Bacteriolysis↗
PubMedDate not supplied

The ground substance of the arterial wall. Part 1. Extractability of glycosaminoglycans and the isolation of a proteoglycan from bovine aorta.

Water and glycosaminoglycan contents were measured in upper and lower thoracic aortas of claves and steers. The ability of various molarities of guanidine hydrochloride to extract glycosaminoglycans from these tissues was assessed. Some glycosaminoglycans seem to be more resistant to extraction than others. A procedure is described for the isolation of a proteoglycan. The molecule appears to contain both dermatan sulfate and chondroitin sulfate. It also seems to be less dense than cartilage proteoglycans extracted by similar methods as assessed by its behavior in centrifugal fields. The properties, locus and biological activities of this molecule are currently being studied.

Age Factors↗