Martin Porvaznik

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Ultrastructural observations of rat seminiferous tubules show clearly the presence of plasma membrane junctions between Sertoli and germ cells in the basal and adluminal compartments. Results obtained from the freeze fracture and thin section techniques were correlated in order to elucidate the nature of these intercellular junctions. We suggest that these(More)
An in vitro monocyte-macrophage colony-forming cell (M-CFC) has been detected in canine bone marrow (BM). The colonies derived from these progenitor cells were similar to murine-derived M-CFC (MacVittie and Porvaznik, 1978, J. Cell Physiol. 97:305--314) colonies, since they showed a singular macrophage line of differentiation, a lag of 14--16 days before(More)
Increased use of the biocidal compound tri-n-butyltin (TBT) in antifouling paints has prompted research aimed at determining the mechanism for TBT toxicity. Past investigations indicate that the primary cellular target for TBT is the cell membrane. Erythrocyte suspensions treated with TBT concentrations 2 greater than or equal to 5 microM undergo hemolysis(More)
Hydrophobic tributyltin (TBT) compounds at concentrations greater than 10 microM caused hemolysis of human erythrocytes and formed structures in plasma membranes. The mercapto compounds, beta-mercaptoethanol (beta MER), 2,3-dimercaptopropanol (BAL), 2,3-dimercapto-1-propane sulfonate (DMPS), DL-dithiothreitol (DTT), and meso-2,3-dimercaptosuccinic acid(More)
Freeze-fracture and thin-section methods were used to study tight junction formation between confluent H4-II-E hepatoma cells that were plated in monolayer culture in media with and without dexamethasone, a synthetic glucocorticoid. Three presumptive stages in the genesis of tight junctions were suggested by these studies: 1) "formation zones" (smooth(More)
Histamine infused into the mesenteric artery of the rabbit ileum ruptured tight junctional complexes linking goblet cells with neighboring absorptive epithelial or other goblet cells. Loss of tight junctional integrity induced by histamine could contribute to extra-intestinal endotoxemia reported after a variety of injuries.
Organotin compounds examined in this study exhibited a relative order of potency for induction of in vitro hemolysis in human erythrocytes as follows: tri-n-butyltin > tri-n propyltin > tetra-n-butyltin > triphenyltin chloride > tri-n-ethyltin bromide > dibutyltin dichloride > stannous chloride > tri-n-methyltin chloride = butyltin chloride dihydroxide. All(More)