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Biomedical subjects

T Shimada

Publications and source records attributed to T Shimada.

At least 1,009 records · Page 56Linked to original sources
PubMed1979

Mutagenic effects of cadmium on mammalian oocyte chromosomes.

When female golden hamsters were treated with cadmium chloride at the oogenesis stages of diakinesis/metaphase I to metaphase II, oocytes with the chromosomal complements of hyperhaploidy and diploidy, as well as oocytes at the anaphase-I stage, were observed. Oocytes of this species were especially sensitive to cadmium. Chromosome analysis of metaphase-II oocytes seems to be a useful method for the screening of mutagenicity of environmental contaminants in mammalian germ cells in vivo.

Animals↗
PubMed1979

Inhibition of rat mast cell degranulation and histamine release by histamine-rat gammaglobulin conjugate.

Histamin-rat-gamma-globulin conjugate inhibited degranulation and histamine release of rat peritoneal mast cells to a greater extent than the rat globulin or histamine alone. Since mast cells contain histamine receptors, it may be assumed that the histamine bound to the gamma-globulin combines with the rat mast cell histamine receptor and inhibits the degranulation and histamine release by a feedback mechanism.

Animals↗
PubMed1979

Superoxide dismutase activity in the maternal and cord blood.

Superoxide dismutase (SOD) activity was measured in the maternal and cord blood by the modified method of Beauchamp and Fridovich, using a carbonate-buffered (pH 10.2) xanthine-xanthine oxidase system. No great differences between maternal and cord blood in erythrocyte SOD levels were observed, with the exception of whole blood; namely, washed RBC showed a SOD activity of a fairly high level, which was comparable to the activities of crude SOD, but showed no difference between them. In contrast, the SOD activity in the maternal whole blood was significantly lower than that in the cord blood. In measuring SOD activity, the serum factor has a great effect, and serum contains a substance that inhibits NBT reduction. Only one band of SOD has been detected which shows identical Rf values both in maternal and cord blood by polyacrylamide-gel electrophoresis.

Electrophoresis, Polyacrylamide Gel↗
PubMed1979

Acute aortic regurgitation with congestive heart failure due to bacterial endocarditis: diagnosed by echocardiogram and treated successfully by surgery (a case report).

A 23-year-old Japanese male with no evidence of previous heart disease was presented with bicuspid aortic valve and a life threatening acute aortic regurgitation due to subacute bacterial endocarditis. By echocardiographic techniques, a precise diagnosis was made based on the following findings: 1) premature mitral valve closure, 2) snowfall-like echoes between the systolic aortic cusps, 3) eccentricity of a diastolic aortic valvular echo. The echocardiographic diagnosis was confirmed on surgery, in which aortic valve replacement was performed with satisfactory postoperative results.

Adult↗
PubMed1979

Evaluation of color discrimination in the white region.

Reference and test stimuli were produced on two separate color television screens to evaluate the color discrimination ability of the human eye for near-white colors. Each test stimulus had a luminance approximately equal to that of the reference, but was slightly different in chromaticity, e.g., [deltax] less than 0.01, [deltay] less than 0.01. The evaluation involved 20 persons observing 26 sets of color stimuli of 16-cd/m2 luminance, and 21 persons observing sets of color stimuli of 253 cd/m2. Observers were requested to categorize the color differences they perceived on a six-level rating scale. The results indicate that the differential thresholds for color difference of near-whites are between 4 and 8 CD (Color Difference), except in the bluish region.

Color Perception↗
PubMed1979

Surface view of pericytes on the retinal capillary in rabbits revealed by scanning electron microscopy.

Retinal capillaries of the rabbit were treated with HCl and collagenase to visualize the pericytes attached to the stromal surface of the capillary walls under the scanning electron microscope. Two types of pericytes were distinguishable on the basis of shape and localization. One type (Type I) had a slightly bulged, fusiform cell body with a few, long, branching cytoplasmic processes, and these cells were scattered mainly in the region of the true capillary. The other type (Type II) possessed a rather flattened and polymorphic cell body from which radiated short irregular cytoplasmic processes, and these cells, which tended to overlap more or less, were present predominantly in the region of the pre- or postcapillary vessels in the capillary bed. The latter type cells were assumed to be precursors of the smooth muscle cells.

Animals↗
PubMed1979

Numerical classification of Yersinia enterocolitica and relationship between its subdivision and pathogenicity.

A total of 102 strains of Yersinia enterocolitica were studied on their morphology, physiology and biochemistry at 25 degrees C. All data coded in binary notation and similarities between each pair of strains by simple matching coefficient were calculated using subsequent computation. Four clusters were distinguished within the 102 strains at a similarity level of 90--93%. Although some discrepancies were recognized on reactions of indole, xylose, esculin and salicin, it was evident that 3 of the 4 groups in the present study correspond to the DNA relatedness groups of Brenner et al., respectively. On the other hand, it was confirmed, using feeding tests with monkeys, that only the group 1 was enteropathogenic. These results support the suggestion of Brenner et al. that their DNA relatedness group 1 is true Y. enterocolitica.

Animals↗
PubMed1978

Two epidemics of diarrhoeal disease possibly caused by Plesiomonas shigelloides.

Two epidemics of water-borne diarrhoeal disease involving a total of 1000 persons are reported. In both epidemics, none of the usual bacterial entero-pathogens were recognized and Plesiomonas shigelloides was the only suspect aetiological agent isolated. The ecology of P. shigelloides was investigated in these outbreaks. It was recognized as an inhabitant of fresh surface water and its presence was closely related to warm weather.

Bacterial Infections↗
PubMed1978

Differential susceptibilities of DNA polymerases-alpha and -beta to polyanions.

The effects of various polyanions including synthetic polynucleotides on DNApolymerases-alpha and -beta from blastulae of the sea urchin Hemicentrotus pulcherrimus and HeLa cells were studied. Only DNA polymerase-alpha was inhibited by polyanions, such as polyvinyl sufate, dextran sulfate, heparin, poly(G), poly(I), poly(U) and poly(ADP-Rib). Of the various polynucleotides tested, poly(G) and poly(I) were the strongest inhibitors. Kinetic studies showed that the Ki value for poly(G) was 0.3 microgram/ml and that poly(G) had 20-fold higher affinity than activated DNA for the template-primer site of DNA polymerase-alpha. Poly(U) and poly(ADP-Rib) were also inhibitory, but they were one hundredth as inhibitory as poly(G) or poly(I). Poly(A), poly(C), poly(A).poly(U) AND POLY(I).poly(C) were not inhibitory to DNA polymerase-alpha. In contrast, DNA olymerase-beta was not affected at all by these polyanions under the same conditions.

Animals↗