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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 1,423 records · Page 79Linked to original sources
PubMed1971

The molecular organization of lipids in the membrane of Escherichia coli: phase transitions.

X-ray diffraction techniques have been used to investigate the physical state of the lipids in the membrane of an unsaturated fatty acid auxotroph of Escherichia coli. Thermotropic phase transitions have been detected in membranes prepared from cells grown on various fatty acid supplements. Below the transition temperature, the X-ray diffraction pattern features a sharp ring at 420 pm (4.2 A) due to the close hexagonal packing of the apolar groups of the lipids; above the transition temperature the lipids are in a less organized liquid-crystalline state that gives rise to a diffuse band centered at a Bragg spacing of 460 pm (4.6 A). This transition occurs at or below the temperature at which the cells were grown. Disparities between this transition temperature and the temperature of discontinuities in the Arrhenius plots for proline transport and succinic dehydrogenase activity lead us to conclude that the distribution of lipids within the membrane is heterogeneous.

Cell Membrane↗
PubMed1971

Insulin-sepharose and the dynamics of insulin action.

In terms of the rate of accumulation of alpha-aminoisobutyric acid, mammary epithelial cells from mature virgin mice respond rapidly to insulin covalently bound to sepharose particles, but do not respond initially to soluble insulin in vitro. The response to insulin-sepharose is prevented if the cells are first exposed to insulin. These observations may provide new insight into the dynamics of insulin action.

Aminoisobutyric Acids↗
PubMed1970

Development of insulin-sensitivity by mouse mammary gland in vitro.

Explants from mammary gland of pregnant mice are sensitive to insulin, but corresponding explants from mature, virgin mice are insensitive to insulin in certain respects. Isolated virgin tissue can acquire insulin-sensitivity independent of exogenous insulin. Some endocrinological and developmental implications are discussed.

Aminoisobutyric Acids↗