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Biomedical subjects

M Koike

Publications and source records attributed to M Koike.

At least 451 records · Page 25Linked to original sources
PubMed1981

[Quantitative cineangiographic evaluation of the valvular regurgitant flow ratio by digital image processing technique (author's transl)].

By application of digital image processing technique to cineangiogram, possibility to calculate the valvular regurgitant flow ratio, especially in patents with aortic regurgitation, was examined. The image processor used was RT6404 made by Amast Computer CO, and the microcomputer to control the image processor was H68TR made by Hitachi Industrial Co. The image of the cineangiogram was photographed by televicamera, and the image processor converted the televi-signal to digitized image. Total volume and concentration of contrast medium in the ventricle was integrated in each systole and diastole. In patients without aortic regurgitation, the volume of contrast medium was not increased in the next diastole after the end of injection. On the contrary, in cases of aortic regurgitation, the volume of contrast medium was increased in the next diastole because of regurgitation. Thus, the regurgitant flow ratio could be calculated from the ejected volume in systole immediately before this diastole and the increased volume caused by the regurgitation.

Aortic Valve Insufficiency↗
PubMed1979

Tumors of Sprague-Dawley rats induced by long-term feeding of phenacetin.

Carcinogenicity of phenacetin was tested using Sprague-Dawley rats. Two groups of animals containing 50 males and 50 females per group were fed respectively with 2.5% and 1.25% phenacetin diet for 18 months and fed thereafter with basal diet for 6 months. Control animals containing 65 males and 65 females were fed with basal diet for 24 months. Animals surviving more than 24 months were regarded as effective animals and killed. Rats that died of tumor development within 24 months were also regarded effective animals. Every organ from the killed and dead animals was fixed in 10% formaldehyde solution and examined histopathologically. Effective number of rats was 27 males and 27 females in 2.5% phenacetin feeding group, and 22 males and 25 females in 1.25% phenacetin feeding group. In control group, 19 males and 25 females were effective. Neoplasms including spontaneous tumors were detected in 26 out of 27 males (96.3%) and 21 out of 27 females (77.8%) of 2.5% phenacetin feeding group, and in 20 out of 22 males (90.9%) and 19 out of 25 females (76.0%) of 1.25% phenacetin feeding group. In control group, 1 out of 19 males (5.3%) and 6 out of 25 females (24.0%) showed spontaneous tumor development. Histopathologically, carcinomas of the nasal cavity, such as adenocarcinoma, squamous cell carcinoma, and transitional cell carcinoma, and the urinary passage, as renal cell carcinoma of the kidney pelvis, and transitional cell carcinoma of the urinary bladder, were most conspicuous, suggesting the target organs of phenacetin carcinogenesis. Males showed higher tumor incidence compared to females. The higher the concentration of phenacetin given, higher incidence of tumors was observed.

Adenocarcinoma↗
PubMed1978

Inhibition of cell division of Escherichia coli by a new synthetic penicillin, piperacillin.

The mechanism of the action of piperacillin against Escherichia coli was investigated. This drug converted cells to filaments, but did not show lytic action in a range of concentrations below 25 mug/ml. In some of the filaments, stretched constrictions with various diameters were observed. Addition of piperacillin to a synchronous culture inhibited cell division immediately at any stage of the cell cycle. The results of morphological examination of synchronous cultures show that the percentage of filaments with a stretched constriction corresponds to that of normally septated cells before addition of the drug. Furthermore, peptidoglycan synthesis and cross-linking were not inhibited by this drug. It is likely that this drug inhibits only septum formation, but not the growth of wall, and that stretched constrictions are a result of longitudinal growth of septation caused by the drug. Examination of affinity of the drug to penicillin-binding proteins shows that protein 3 is the most sensitive, proteins 2 and 7 are moderately so, and protein 1 is sensitive only to high concentrations of the drug.

Bacterial Proteins↗
PubMed1977

Effect of dihydroxymethyl furatrizine on cell division of Escherichia coli.

Antibacterial activities of 3-di(hydroxymethyl) amino-6[2-(5-nitro-2-furyl)vinyl]-1,2,4-triazine, (dihydroxymethyl furatrizine) were investigated using mutant strains of Escherichia coli lacking repair systems for DNA damage, i.e. polA, uvrA, uvrA, uvrC, recA, recB, recC and uvrArecA. All of the mutant strains were more sensitive to the drug than the parent sgrains, as was the case with the sensitivity to UV-irradiation. These results indicate that the drug acts lethally on sensitive bacteria by damaging their DNA, and parts of the damaged DNA are repaired by excision and recombinational repair systems. Filamentous cell formation was induced in all strains except the uvrArecA strain by sublethal concentration of the drug, as well as by UV-irradiation. It is possible that the occurrence of the short period of "unbalanced growth" induced by such DNA damaging agents leads to filament formation. In the cells of the double mutant, filament formation was induced by the drug but not by UV-irradiation, and the majority of the filamentous cells formed were multinucleated. This suggests that, in this double mutant, the drug directly reacts with the septation mechinery of the cell envelope, resulting in filament formation. This hypothesis is supported by the electron microscopic observations that septation is interrupted in the filamentous cells induced by the drug.

Anti-Bacterial Agents↗