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Biomedical subjects

S Katoh

Publications and source records attributed to S Katoh.

At least 361 records · Page 20Linked to original sources
PubMed1980

Dihydropteridine reductase and tetrahydropterin in Crithidia fasciculata cells.

Dihydropteridine reductase was found in extracts of Crithidia fasciculata and was demonstrated by the fact that the enzyme required both quinonoid-dihydropterin and NADH as substrates. 7,8-Dihydropterin and dihydrofolate failed to serve as substrates; tetrahydropterin was formed as the reaction product. The molecular weight of the enzyme was estimated to be about 55 000 by Sephadex G-100 gel filtration. NADH was more effective than NADPH as substrate for the enzyme. Tetrahydropterin (1.35 nmol tetrahydrobiopterin equivalents/g cells) was also detected in C. fasciculata.

Aminopterin↗
PubMed1979

Two electrogenic mechanisms contributing to the 560 nm absorption changes in intact Bryopsis chloroplasts.

Light -induced absorbance changes at 560 nm in dark-adapted intact chloroplasts of the green alga, Bryopsis maxima were studied in the time range of 200 ms. The initial rise of the 560 nm signals consists of two major components which are both electrochromic absorbance changes of the carotenoids, siponein and/or siphonaxanthin, but different in mechanisms of the field formation. The first component (component S) is related to electron transport since it was sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) and showed at light-intensity dependence similar to that of electron transport in chloroplasts. In the presence of DCMU, component S could be restored on addition of proton-transporting electron donors such as reduced 2.6-dichlorophenol indophenol and phenazine methosulfate, but not on addition of N,N,N',N'-tetramethyl-p-phenylenediamine which does not carry protons with electrons (Trebst, A. (1974) Annu. Rev. Plant Physiol. 25, 423--458). We propose that component S is due to the electric field set up by the proton translocation across the thylakoid membrane. The second component (component R) was resistant to DCMU and DBMIB. The light-intensity dependency of component R was similar to that of cytochrome f photooxidation which showed saturation at a relatively low light intensity. The magnitude of component R was markedly reduced by phenylmercuric acetate, suggesting the participation of ferredoxin and ferredoxin-NADP oxidoreductase in the mechanism of the field formation responsible for this component. In the presence of DCMU and phenylmercuric acetate, time courses of the 560 nm changes paralleled those of cytochrome f changes. These results indicate that component R is due to the electric field formed between oxidized cytochrome f and other intersystem electron carriers located in the inner part of the thylakoid membrane and reduced electron acceptors of Photosystem I situated on the membrane surface. The complex natures of the 560 nm changes, as well as the contributions of Photosystems I and II to the absorbance changes, are explained in terms of the two electrogenic mechanisms.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed1979

A study on tension signs in lumbar disc hernia.

The laminae were removed from the lower lumbar spines of five cadavers within four hours of death. A short length of rubber tube was inserted between the nerve roots and the lumbar disc and the tension monitored using semiconductor pressure transducers. The angulatory stresses exerted on the lumbar nerve roots during tension sign tests were found to correspond to clinical experience.

Adolescent↗
PubMed1978

Endoscopic studies on the minute structures of colonic mucosa in the follow-up observation of ulcerative colitis.

Thirty cases of ulcerative colitis were examined endoscopically by means of magnifying colonoscope with dye spraying method (the combined method), and their minute mucosal structures were classified into four categories endoscopically, which correlated well with the histological findings. By this procedure, it was easy to detect the subsidence of inflammation of the mucosa in the quiescent phase or to reveal the active inflammatory involvement of the bowel. Moreover, inspecting the minute changes of the colonic mucosa detected by the combined method, remission was more correctly decided and rigid control is contributing to the decrease in the recent rate of recurrence of ulcerative colitis.

Adolescent↗
PubMed1977

On the dye spraying method in colonofiberscopy.

Dye spraying method was applied in colonofiberscopy; 111 cases of normal colonic mucosa and 26 cases of ulcerative colitis were examined by this method. Using indigocarmine in this method, we could recognize the fine mucosal changes more easily and clearly and get better information for differential diagnosis. Furthermore, the degree of staining of the mucosa by methylene blue, one of the ultra vital staining dye, is different according to the stage of the inflammatory process of colonic mucosa itself in ulcerative colitis. Namely the stainability of the colonic mucosa is corresponding to the healing process of the disease.

Adult↗