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Biomedical subjects

M M Burger

Publications and source records attributed to M M Burger.

At least 181 records · Page 10Linked to original sources
PubMed1972

Selective inhibition of growth of transformed cells by protease inhibitors.

Five protease inhibitors with different modes of action were found to reduce the growth of transformed mouse (Py3T3, SV3T3, and 3T12) and hamster (PyBHK) cells. Some of these inhibitors caused the transformed cells to cease growth at saturation densities characteristic for nontransformed cells. The protease inhibitors were strikingly selective with regard to the transformed cells; they had essentially no effect on the growth of the nontransformed cells. From this result, it is concluded that the inhibitors block a protease-like activity that is required for the unrestrained growth of transformed cells. The inhibitors exerted their effect directly on the cells; they did not affect growth by interacting with serum components of the medium.

Animals↗
PubMed1971

Cyclic membrane changes in animal cells: transformed cells permanently display a surface architecture detected in normal cells only during mitosis.

A membrane site exposed only during mitosis in normal 3T3 cells, but exposed in all polyomavirus transformed 3T3 (Py3T3) cells, has been detected The site was identified by the specific binding of a wheat-germ agglutinin conjugated with fluorescein isothiocyanate. The receptor site has been studied previously. It binds wheat-germ agglutinin, causing the selective agglutination of Py3T3 cells, but not normal 3T3 cells. A short treatment with low concentrations of trypsin exposes cryptic sites in 3T3 cell membranes; this permits agglutination of these cells. The experiments reported here indicate that these sites normally are exposed during a brief period of the cell cycle for 3T3 cells. Specific hapten inhibitors of agglutination also inhibit the binding of the conjugated agglutinin and prevent fluorescence.

Animals↗
PubMed1971

Temperature-dependent surface changes in cells infected or transformed by a thermosensitive mutant of polyoma virus.

Infection of BALB/3T3 cells by polyoma virus causes an alteration in the cell surface, characterized by enhanced agglutination of the cells by wheat germ agglutinin or concanavalin A. Infection by the thermosensitive mutant of polyoma, ts-3, causes the cell surface alteration at the permissive temperature, but not at the nonpermissive temperature. The cell surface alteration requires cellular DNA synthesis, but not viral DNA synthesis. BHK cells transformed by ts-3 show the surface alteration when grown at the permissive temperature, but not when grown at the nonpermissive temperature. It is concluded that the surface alteration in transformed cells is under the control of a viral gene.

Agglutination↗
PubMed1970

Absence of a cell membrane alteration function in non-transforming mutants of polyoma virus.

A surface receptor for an agglutinin, exposed in transformed but not in normal cells, arises in normal mouse cells during lytic infection by polyoma virus. The structural change in the surface membrane characteristic of transformed cells and of cells productively infected by wild type virus fails to occur in normal mouse cells infected by mutants of the virus that are unable to cause transformation. The exposure of the receptor site by wild type virus is reversibly blocked by inhibitors of DNA synthesis.

Agglutination Tests↗
PubMed1969

A difference in the architecture of the surface membrane of normal and virally transformed cells.

Several tissue culture cell lines that were transformed by a tumor virus have been found to react with an agglutinin, while under identical conditions their untransformed parent cell lines did not agglutinate. Since a short treatment of the parent cell line with low concentrations of proteases exposed the same agglutinin receptor sites in a fashion indistinguishable from the transformed cells, it is proposed that both viral and chemical transformation produce changes in the architecture of the membrane, identical to those of the proteases.

Animals↗