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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 757 records · Page 42Linked to original sources
PubMed1977

Dose effect relationship for epilation and late effects on spinal cord in rats exposed to gamma rays.

The response of rat spinal cords (T7-T12) exposed to single and multifractionated gamma-ray exposures revealed no significant differences between the threshold doses for 2 fractions given with a 24-hr. interval and 2 fractions given with a 15-day interval. The latent period for spinal cord damage was about 190 days when the incidence of paralysis was high; it was less than this in animals with a lower probability of paralysis. There was a marked sparing effect from dose fractionation: the initial part of a Strandqvist type of isoeffect curve had a slope of 0.44 for doses causing paralysis in 50% of the animals, and 0.36 for "threshold" doses. The level of epilation was not useful for predicting spinal cord damage.

Animals↗
PubMed1977

Effect of vagotomy on hyperinsulinemia in obese rats with hypothalamic lesions.

With the purpose of investigating the pathogenesis of obesity and hyperinsulinemia in rats with hypothalamic lesions (HTL), HTL were made in vagotomized rats, and the development of obesity was serially followed up to 15 weeks as well as the changes of plasma triglyceride and immunoreactive insulin (IRI) levels. Even in vagotomized rats, obesity developed after HTL and plasma triglyceride and IRI levels increased significantly. However, obesity was slightly less in grade and occurred later as compared with sham-vagotomy-HTL rats. Plasma IRI levels in vagotomized rats significantly correlated with the body weight, Lee's index, the weight of adipose tissue and plasma triglyceride level. Similar results were also obtained in rats with HTL which were pair-fed following vagotomy. These results suggest that the hyperinsulinemia in obese rats with HTL may be involved not only by hypersecretion of insulin mediated by hypothalamo-vagal nerve system but also by some insulin-antagonistic factors such as increases of adipose tissues and plasma lipids.

Animals↗
PubMed1977

Breakdown of the blood: aqueous barrier and prostaglandins.

The quantitative relationship between the degree of breakdown of the blood-aqueous barrier and aqueous humor prostaglandin content was studied in rabbits. After the primary aspiration of the aqueous, secondary aqueous humor was sampled. The samples were divided into two parts for the following measurements: one for the degree of the barrier breakdown which was represented by protein content determined by Lowry method and the other for prostaglandin content which was measured by radio-immunoassay. A significant linear relationship was obtained between the protein and prostaglandin E content but not between the protein and prostaglandin F content.

Animals↗
PubMed1977

Modifications of the biological activity of anti-D immunoglobulin caused by heat aggregation.

Some of the biological activities known to be confined to certain anti-D sera such as Ripley could be simulated using heat-treated human anti-D Ig preparations. Thus, human red cells sensitized with heat-treated anti-D Ig were found to be capable of causing Fc-receptor on lymphocyte surfaces and of fixing complement. In its other effects such as reactivity to rheumatoid factor and to anti-allotype agglutinators, heat-treated anti-D Ig seemed inferior to such anti-D sera as Ripley.

Chromatography, Gel↗
PubMed1976

Effect of viomycin on dihydrostreptomycin binding to bacterial ribosomes.

Viomycin, a peptide antibiotic, reduced the amounts of dihydrostreptomycin bound to ribosomes of Myobacterium smegmatis and Escherichia coli, although they have different modes of action. The [3H]dihydrostreptomycin binding to ribosomes could not exchanged with streptomycin or dihydrostreptomycin, but not with unrelated antibiotics, namely, kanamycin, neomycin, spectinomycin, capreomycin, tuberactinomycin-N, chloramphenicol and erythromycin. We suggest that there is a significant interaction between the binding sites of viomycin and streptomycin on ribosomes.

Anti-Bacterial Agents↗
PubMed1976

Effects of prostaglandins on leukocyte migration.

Artificially synthesized prostaglandins (PGE1, PGE2, PGF1alpha, and PGF2alpha) were found, using Boyden's chamber, to induce significant migration of polymorphonuclear leukocytes (PMNs) of the rabbit; PGF2alpha had greater effects than PGE1 or E2. A typical dose dependent relationship was found between the PMNs migration and PGF2alpha concentrations. Indomethacin pretreatments of rabbits did not significantly alter the PMNs migration indicating that PGs synthetized in vivo was not involved in the migration. PGF2alpha was placed in the lower compartment opposite to PMNs and also in the upper compartment together with PMNs. No significant difference was found in the number of migrated PMNs between the two experimental conditions. PGs diffusion occurred across the millipore filter separating the two compartments where the concentrations were almost equal at the end of 3 hours incubation. It was thus concluded that PGs effects are to induce random PMNs movements rather than to initiate chemotactic directional migration.

Animals↗
PubMed1976

Altered ribosomes in antibiotic-resistant mutants of Mycobacterium smegmatis.

Two alleles for viomycin-capreomycin resistance (vic) in Mycobacterium smegmatis affect ribosome structures. One (vicA) affects a component of 50S subunits and the other (vicB) affects a component of 30S subunits. The locus for neomycin-kanamycin resistance (nek), which is linked to vicA and vicB, affects a component of 30S subunits. Although the erythromycin resistance locus (ery) is linked to vic and nek, no ribosomal alterations could be detected. Mutations at the streptomycin locus (str) not linked to vic and nek caused alterations of 30S subunits.

Anti-Bacterial Agents↗
PubMed1976

Method of constructing a dose-response curve for normal cells in situ.

A method is presented for planning experiments and analysing data with a view to determining in detail the shape of a single-dose survival curve for normal cells exposed in situ to relatively low doses of radiation. Applying this method to data published on the responses of gastric mucosal and colonic stem cells showed that the single-dose survival curves for these cells were linear up to about 250 rads, after which they bent downwards. Some applications of this method are discussed.

Animals↗