The uptake and subcellular localization of selenium-75 was examined in 3 established mammary cell lines in vitro. Previous studies had demonstrated that cell line YN-4 exhibited a biphasic growth response to selenium, whereas cell lines CL-S1 and WAZ-2t exhibited only an inhibition of growth. All 3 cell lines incorporated selenium-75 readily over a 48-h incubation period and the concentration of selenium-dependent glutathione peroxidase was correlated with the level of selenium-75 uptake. However, neither of these 2 parameters could be related to the unique biphasic growth response exhibited by cell line YN-4. The intracellular localization of selenium-75 was similar in lines CL-S1 and YN-4 with the label incorporated primarily in the cytosol and secondarily in the mitochondria. Although the unique growth response of line YN-4 could not be attributed to the incorporation parameters examined herein, the stable incorporation of selenium-75 at high levels should make these lines useful for further studies on the subcellular localization of selenium into organelles and macromolecules.

Animals↗

PubMedDate not supplied

Mycotic keratitis in Paraguay.

Patients with corneal ulcer, residing mainly in rural areas of Paraguay, were controlled for mycotic eye infections. In 26 cases out of 45 (58%) presence of filamentous fungi was observed (Fusarium sp. (11), Aspergillus sp. (5), Cladosporium sp. (3), Alternaria sp. (2), Acremonium sp. (1), Curvularia sp. (1), culture negative (3)). In 17 cases also pathogenic bacteria were present. Most of the patients were farmers and belonged to the low income class. These data indicate that mycotic keratitis may be a frequent cause for eye infections in developing countries.

Adolescent↗

PubMedDate not supplied

Selenium distribution in mammary epithelial cells reveals its possible mechanism of inhibition of cell growth.

The subcellular and macromolecular distribution of 75Se-selenite was determined in murine mammary epithelial cell lines which demonstrated marked differences in their growth response to 5 microM selenite. MOD cells responded sooner to the inhibitory effects of selenite than COMMA-D cells. The MOD cells also incorporated a slightly higher percentage of 75Se-selenite into proteins and attained a higher ratio of selenoprotein to selenonucleic acids than did COMMA-D cells. Most selenium and selenoproteins were located in the cytoplasm as revealed by autoradiography and subcellular fractionations. These data suggest that a cytoplasmic selenoprotein may be an intermediate for selenite's nontoxic growth inhibitory effects.

Animals↗

PubMedDate not supplied

Proposed mechanisms for selenium-inhibition of mammary tumorigenesis (review).

Both the reduced and oxidized forms of selenium are available at various rates through a common selenium pool for incorporation into selenoproteins, of which glutathione peroxidase is the best studied. Dietary selenium as selenite and selenomethionine decreased the incidence of rodent mammary tumorigenesis. The postulated mechanisms of this inhibition includes alterations in the level of GSHPX, membrane peroxidation, glutathione, immune functions, induction of specific selenoproteins, alterations of carcinogen metabolism, and the effect of various chemical forms of selenium. After many studies the mechanism of action of selenium in the inhibition of mammary tumorigenesis is still unknown, although studies of the role of selenoproteins appears the most promising.

Animals↗

PubMedDate not supplied

Distribution of selenium-binding proteins in different tissues of the mouse and rat.

The distribution of selenium-binding proteins in specific tissues of mice and rats was examined by electrophoretic and immunologic techniques. Major selenium-binding proteins of 58K and 26K daltons were present in whole blood, erythrocytes, liver, duodenum, mammary tumors, kidney, testis, ovary and pancreas by electrophoretic analysis. By Western immunoblot it was evident that the 58K protein in plasma did not cross-react with the cellular 58 K protein. Furthermore, muscle did not exhibit any immunologically recognizable 58K protein. The antibody raised against mouse liver 58K recognized a similar protein in rat liver, kidney and testis. The 58K selenium-binding protein appeared to be concentrated in tissues enriched in G1 and the effect of hydroxyurea on selenium-binding protein levels suggested the 58K selenium-binding protein appeared to be made predominantly during the G1 phase of the cell cycle. Evidence is also presented that whole blood contains selenium bound to hemoglobin which supports prior evidence by other investigators. These results further support the evidence for tissue selenium-binding proteins other than glutathione peroxidase and document the immunological specificity and reactivity of a new antibody against a selenium-binding protein.

Animals↗