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Biomedical subjects

M Ohno

Publications and source records attributed to M Ohno.

At least 685 records · Page 38Linked to original sources
PubMed1976

Synthesis of a potential water-soluble radiographic contrast medium, 2, 4, 6-triiodo-3-acetamido-5-N-methylcarboxamidophenyl beta-D-glucopyranoside.

Starting from 3,5-dinitrobenzoic acid, the infinitely water-soluble compound, 2, 4, 6-triiodo-3-acetamido-5-N-Methylcarboxamidophenyl Beta-D-glucopyranoside (9), was synthesized in nine steps. Glucoside 9, the first example of potentially a new class of water-soluble x-ray contrast media, is rapidly excreted from dog's plasma into the urine, unchanged. It has low intravenous toxicity in mice (LD50 = 24.5 g/kg). Thin-layer chromatography of aqueous solutions of 9 revealed first appearance of aglycon 7 after 1 week at room temperature.

Animals↗
PubMed1976

Kinetic study of alpha-chymotrypsin catalysis with regard to the interaction between the specificity-determining site and the aromatic side chain of substrates.

In order to investigate how changes in the structures of side-chain aromatic groups of specific substrates influence binding and kinetic specificity in alpha chymotrypsin [EC 3.4.21.1]-catalyzed reactions, a number of nucleus-substituted derivatives of the specific ester substrates were prepared and steady-state kinetic studies were carried out at pH 6.5 and 7.8. Ac-Trp(NCps)-OMe was hydrolyzed more readily at low substrate concentration than Ac-Trp-OMe due to its smaller Km(app) value, suggesting that the bulky 2-nitro-4-carboxyphenylsulfenyl moiety interacts with outer residues rather than with those in the hydrophobic pocket and that this interaction increases the binding specificity. Inhibition experiments using the corresponding carboxylate and analogous inhibitors, however, showed that the carboxy group at the para position of the phenyl nucleus of the substituent sterically hinders association with the active site of alpha-chymotrypsin at pH 7.8 but not at pH 6.5. The kcat values of Ac-Trp(CHO)-0Me, Ac-Tyr(3-NO2)-OMe, and Ac-m-Tyr-OMe were much higher than those of the corresponding specific substrates, indicating that derivatives with a substitute as large as a formyl, nitro or hydroxyl group at the xi-position are stereochemically favorable to the catalytic process. Remarkable increases in Km(app) were also observed. The individual parameters for Ac-Dopa-OMe, however, were comparable to those for Ac-Tyr-OMe.

Amino Acids↗
PubMed1975

Intralobar pulmonary sequestration; with special emphasis on bronchial communication.

The radiologic and pathologic features of eight cases of intralobar pulmonary sequestration are reported. Special attention was given the communication between the cystic areas and the normal bronchial tree. In three of five surgical specimens, probing revealed such communications. Microscopically, the transition from the normal bronchus to the cysts revealed no inflammation to suggest fistulous communication secondary to infection. The possibility of preexisting congenital bronchocystic communications within the pulmonary sequestrations was therefore suggested.

Adolescent↗
PubMed1975

alpha-Chymotryptic hydrolysis of derivatives of the specific substrates with substituents in the nucleus.

Steady state kinetic studies of alpha-chymotrypsin [EC 3.4.21.1]-catalyzed hydrolysis of nucleus-substituted derivatives of the specific substrates were made at pH 6.5 and 7.8. Ac-Trp(NCps)-OMe was hydrolyzed more readily than Ac-Trp-OMe owing to its smaller Km value. The kcat values of Ac-Trp(CHO)-OMe and Ac-Tyr(3-no2)-ome were higher than those of the corresponding unmodified substrates, suggesting that derivatives with a substituent as large as a formyl or nitro group at the epsilon-position are stereochemically favorable to the catalytic process. Derivatives of Ac-Phe-OMe with a chain of four atoms at the 3 or 4-position of the phenyl nucleus and 2,3-dihydropyrrolo[2,3-b]indoles derived from Ac-Trp-OMe were not hydrolyzed at all.

Chymotrypsin↗