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Biomedical subjects

R C Schoen

Publications and source records attributed to R C Schoen.

7 recordsLinked to original sources
PubMed1985

A coordinate relationship between the GALK and the TK1 genes of the Chinese hamster.

Chinese hamster cells in culture were treated with various concentrations of thymidine, 5-bromodeoxyuridine, trifluorothymidine, and 2-deoxy-D-galactose. Selection was made for deficiencies in the activities of galactokinase and thymidine kinase. Selection in the presence of thymidine, 5-bromodeoxyuridine, and trifluorothymidine was expected to produce clones deficient in thymidine kinase only, whereas those deficient in galactokinase were expected to be selected in the presence of 2-deoxy-D-galactose. However, it was found that clones growing in the presence of these inhibitors were frequently deficient in both enzymes. Or if a clone was deficient in only one, the deficiency frequently was not expected according to the selection procedure. This indicates some sort of coordinate relationship between the two gene loci, GALK and TK1, which specify galactokinase and thymidine kinase, respectively. GALK and TK1 are linked in all primates and rodents in which linkage determinations have been made. It is therefore probable that this linkage has been conserved for a long period of time. It is suggested that the apparent relationship between the two genes shown by the data presented here, as well as by others, supports the conclusion that linkage has been conserved by natural selection and is therefore not fortuitous.

Animals↗
PubMed1984

Thymidine-kinase activity of cultured cells from individuals with inherited galactokinase deficiency.

Cells of a person homozygous for galactokinase deficiency and of her heterozygous parents were found to be deficient in the enzyme thymidine kinase. The decrease in thymidine-kinase activity may be the result of a qualitative alteration in the enzyme molecule. This is reflected in the apparent alteration in the sensitivity of the enzyme to trifluorothymidine. It is suggested that this relationship between the galactokinase and thymidine kinase is not fortuitous but a reflection of their interdependence as found previously in the Chinese hamster.

Alleles↗
PubMed1982

Monoclonal antibody against human fibronectin which inhibits cell attachment.

Monoclonal antibodies have been prepared against both human and bovine fibronectin. Evidence is provided which indicates that nine different antigenic determinants are recognized by the ten antihuman fibronectin monoclonal antibodies isolated. One monoclonal antibody was identified that blocked fibronectin mediated cell attachment without interfering with fibronectin binding to collagen. Sensitive ELISA assays for fibronectins derived from 32 mammalian species have been developed with the monoclonal reagents characterized in this study.

Animals↗
PubMed1981

Adhesive substrates for fibronectin.

In order to promote cell attachment, fibronectin must first undergo activation by a suitable substrate. In this study, 52 materials have been surveyed for their ability a) to bind fibronectin, b) to activate the cell-adhesive property of fibronectin, and c) to support the growth of cells. Many plastics, polysaccharides, metals, and ceramics were found to support cell growth as well as the fibronectin-dependent attachment of cells. Several other substrates have been identified that were inactive in promoting either cell attachment or growth. Hydrophobic substrates were found to be active in fibronectin activation, whereas hydrophilic substrates were found to be inactive. Since fibronectin binds to substrata of extremely varied chemical composition, it is clear that the binding of fibronectin to such substrata is nonspecific in nature. Since protein pretreatment of all substrata, except collagen and poly(L-lysine), abolished the physical binding of fibronectin, the binding of fibronectin to artificial substrata is probably ascribable to a nonspecific hydrophobic protein-substratum interaction. In contrast, several lines of evidence indicate that the interaction between fibronectin and collagen displays biological specificity. Poly(hydroxyethylmethacrylate)(poly(HEMA)), which has previously been shown to be nonadhesive for cells, is demonstrated here to be unique in its inability to bind fibronectin. Addition of one part per million of an adhesive polymer to poly(HEMA) permits fibronectin binding to occur.

Animals↗
PubMed1981

Replica plating of cultured mammalian cells.

A simple device is described which permits the replica plating of lymphocytes as well as substrate adherent fibroblasts. The replica plating device consists of an 8 X 12 array of cotton-tipped swabs (Q-tips). The principle of the replica plating system involves the use of an array of absorbent cotton-tipped swabs to transfer nonadherent lymphocytes (or conditioned medium) to corresponding wells of 96-well microtiter plates. Replica plating of substrate adherent cells requires one additional step; i.e., dislodgement of adherent cells by rotating the cotton-tipped swabs against the culture surface of each well. Once adherent cells are dislodged, replica plating of adherent cells can be carried out in an identical fashion to the replica plating of nonadherent lymphocytes. Application of the Q-tip replicator in the isolation of monoclonal antibody secreting hybridomas is also presented.

Animals↗