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Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 739 records · Page 41Linked to original sources
PubMed1983

Evaluation of the factors influencing the radiosensitivity of mouse ascites tumors.

Factors influencing the radiosensitivity of the newly established mouse ascites tumor TMT-3 line were studied. In vivo radiosensitivity of the tumor cells decreased with the progression of the growth phase in mice. Oxygen depletion was the major cause of the decreased radiosensitivity. Polarographic measurement of the oxygen dissolved in suspension of various cell densities suggested that high cell density such as in the ascites might well cause severe hypoxia. Humoral factors in the ascites and cell-to-cell contact had no effect on tumor cell radiosensitivity when the influence of the repair of potentially lethal damage was excluded.

Animals↗
PubMed1982

Altered cation coupling to melibiose transport in mutants of Escherichia coli.

The alpha-galactoside transport system of Escherichia coli utilizes either H+ of Na+ as a coupling cation for melibiose transport. Mutants were isolated which showed altered cation recognition for melibiose transport. The transport carrier of the mutants has lost the ability to accept H+ but can utilize either Na/ or Li+ for co-transport with melibiose. Such mutants might be predicted if the melibiose carrier were viewed as a descendant of an evolutionary transition between the H+-substrate co-transport systems of primitive cells and the Na+-substrate systems of more complex organisms. A second mutation was found in these mutants which involves the Na+ (Li+)-H+ exchange carrier. The maximal rate of Li+-H+ exchange in one of the mutants was 11 times higher than the parent and the Km for Li+ by this carrier was one-sixth that of the parent.

Biological Transport, Active↗
PubMed1982

Solubilization and reconstitution of the melibiose carrier from a plasmid-carrying strain of Escherichia coli.

A strain of EScherichia coli was constructed containing a plasmid from the Clarke-Carbon collection that showed high levels of melibiose transport activity. Membranes from the plasmid-containing strain were extracted with octyl-beta-D-glucopyranoside and melibiose transport was reconstituted in liposomes. The proteoliposomes exhibited counterflow activity, as well as membrane potential and sodium gradient-driven melibiose accumulation.

Escherichia coli↗
PubMed1982

Decrease in stiffness during shortening in calcium activated skinned muscle fibers.

Single fibers from frog sartorius or semitendinosus muscle were mechanically skinned and activated in ATP salt solution containing 10 micro M Ca2+ (7 degrees C). After development of an isometric contraction, fibers were released at constant speed (0.03-2.4 s-1). During ramp shortening, stiffness was determined from the slope of the tension-length diagram obtained during superimposed quick stretches. Both force and stiffness decreased, as the ramp shortening proceeded and approached a steady value after about 60 ms. An increase in speed of shortening caused a decrease in fiber tension and stiffness and an increase in the ratio of stiffness to tension, suggesting a decrease in both the number of attached crossbridges and in the average force per crossbridge.

Animals↗