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Biomedical subjects

K Hirota

Publications and source records attributed to K Hirota.

At least 505 records · Page 28Linked to original sources
PubMed1977

Ligands and oxidants in ferrihemochrome formation and oxidative hemolysis.

We have investigated the effect of size of a single neutral ring substituent on the induction of hemolytic anemia and the formation of a ferrihemochrome by substituted phenylhydrazines. The severity of induced anemia decreased with increase in size of a halogen atom or an alkyl group ortho to the hydrazino group, little anemia resulting from 2-iodophenylhydrazine and no anemia from 2-tert-butylphenylhydrazine. The size of a halogen atom or an alkyl group at the meta or para position had relatively little effect on the severity of induced anemia. The ability of an arylhydrazine to induce hemolytic anemia paralleled its ability to produce a ferrihemochrome with an exogenous ligand, probably the corresponding aryldiazene. In general, rapid and complete formation of ferrihemochrome occurred with arylhydrazines that induced severe anemia. The degree of hemolysis induced by an arylhydrazine was not related to its rate of autooxidation, i.e., the rate at which oxidants are formed by the reduction of oxygen. We propose a mechanism of arylhydrazine-induced oxidative denaturation based on the simultaneous formation of hydroxyl radical and aryldiazene ferrihemochrome in a reaction of oxyhemoglobin with arylhydrazine. We suggest that after oxidation of the porphyrin ring is initiated by a hydroxyl radical, oxidative cleavage of the ring is facilitated by the presence of a large ligand in the heme crevice. Thus, aryldiazene ferrihemochrome may contribute to instability in a hemoglobin molecule, whereas globin ferrihemochrome results from instability.

Anemia, Hemolytic↗
PubMed1977

Clearance of sulfamethoxazole in eggs and tissues of chickens.

Clearance of sulfamethoxazole (SMX, or sulfisomezole) in eggs and tissues of chicken after withdrawal of the drug which was medicated feed additively (at 0.2 or 0.4%) or administered intramuscularly (100 mg./kg., twice daily) for 5 successive days was determined using a fluorescamine reagent. Clearance patterns of SMX were found to be different between albumen and yolk. SMX level in albumen diminished linearly to below 0.1 p.p.m. (sensitivity level) by 5 days after the cessation of medication. On the other hand, SMX level in yolk remained at a plateau until 4 days, and thereafter decreased linearly to below 0.1 p.p.m. by 10 days. SMX levels in most tissues diminished below 0.1 p.p.m. by 3 days and those in kidney and skin by 4 days. Clearance patterns in tissue were quite similar to those in egg albumen. Proportion of acetylated-SMX to total-one in both albumen and yolk tended to increase up to 10% with the lapse of time after drug withdrawal. Acetylation was high in liver (36.5-43.6%), spleen skin and fat, but low in breast muscle and kidney (3.7-11%) in the groups of feed addition; while acetylation was low in liver of the group of intramuscular injection.

Administration, Oral↗
PubMed1977

Nucleosides. CVI. Syntheses of 1-N-methyl-5-(beta-D-ribofuranosyl)uracil (1-N-methyl-phi-uridine) and its identity with a metabolite elaborated by Streptomyces platensis var. clarensis.

Very recently, 1-N-methyl-psi-uridine was isolated from the culture filtrate of Streptomyces platensis var. clarensis along with an antibacterial and antiviral antibiotic, U-44590. We achieved chemical syntheses of 1-N-methyl-psi-uridine by selective methylation of psi-uridine in two different routes and established the identity of the synthetic nucleoside with the natural product.

Chemical Phenomena↗
PubMed1976

Induction of haemolytic anaemia by substituted phenylhydrazines.

The induction of anaemia and reticulocytosis by arylhydrazines was influenced by substituents on the benzene ring of phenylhydrazine. Arylhydrazines with ortho substituents, which would hinder the binding by haemoglobin of a ligand derived from the arylhydrazine, resulted in the least anaemia and reticulocytosis. These results are consistent with a previous finding that hydrazinobenzoic acid, which did not produce a ferrihaemochrome from ferrihaemoglobin, did not induce anaemia. The parallelism between the formation of a ferrihaemoglobin compound and the induction of anaemia supports the hypothesis that destabilization of haemoglobin by the binding of a ligand derived from the aryl portion of an arylhydrazine is an essential step in arylhydrazine-induced haemolytic anaemia.

Anemia, Hemolytic↗