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Biomedical subjects

R Hayashi

Publications and source records attributed to R Hayashi.

At least 307 records · Page 17Linked to original sources
PubMed1981

[Fundamental and clinica evaluation of cefoxitin in children (author's transl)].

Fundamental and clinical evaluations were made on cefoxitin, a new cephamycin antibiotic, and the following results were obtained. 1) MIC of the drug to clinical isolates was determined and was higher than that of cefazolin to Gram-positive bacilli. Among Gram-negative rods, the drug showed a sufficient antibacterial activity even to cefazolin-resistant strains. However, the MIC of cefoxitin to cefazolin-sensitive strains tended to be higher than that of cefazolin. 2) As to the passage of cefoxitin in experimental staphylococcal meningitis in rabbits, a percentage of CSF/serum ratio of AUC was 10.7% up to 3 hours and CSF/serum ratio of T1/2 was 1.78 of which value was an intermediate between those of ampicillin and cefazolin. There were, however, larger individual differences. 3) Blood concentrations and urinary recovery rates were determined in 2 children. In 1 patient, in whom the drug was given intravenously at a dose of 25 mg/kg, a blood concentration after 30 minutes was 50 microgram/ml, T1/2 was 57.2 minutes. This patient, however, showed a slight renal dysfunction. In another patient, who received an intravenous injection of 12.5 mg/kg, a 30 minutes blood concentration was 14.6 microgram/ml and T1/2 was 31.8 minutes. Urinary recovery rates up to 6 hours were 85.8% and 73.5%, respectively. 4) Thirty patients with the following bacterial infections were treated with cefoxitin, i.e., urinary tract infection (24 cases), respiratory tract infection (4 cases), each one case of peritonitis and suspected sepsis. An overall efficacy rate was 93.3%, i.e., excellent in 13 cases, good in 15, and failure in 2. Disappearance rate of the causative organism of the 23 clinical isolates was 87.0%, i.e., that the causative organism disappeared in 20 strains, reduced in 1 and persisted in 2. 5) Based on the above results, it was concluded that cefoxitin is a potent new antibiotic in bacterial infections in children, particularly respiratory and urinary tract infections. The optimal recommended dose will be about 25 mg/kg which should be given 3-4 times daily intravenously or by drip infusion.

Adolescent↗
PubMed1980

Studies on aspartase. VI. Trypsin-mediated activation releasing carboxy-terminal peptides.

Aspartase (L-aspartate ammonia-lyase, EC 4.3.1.1) of Escherichia coli, already of full activity, is 3-5-fold activated by a limited proteolysis with trypsin (Mizuta, K. and Tokushige, M. (1976) Biochim. Biophys. Acta 452, 253-261). Structural bases for the activation were investigated. The NH2-termini of the native enzyme and of the trypsin-activated enzyme were found to be equally serine, as analyzed by the dansylation method. However, the COOH-terminal glutamate of the native enzyme was altered to arginine upon activation, as revealed by treatments with carboxypeptidases Y, A and B. The released peptides were obtained by molecular sieve membrane filtration following trypsin activation of the enzyme. The peptides were separated by high voltage paper electrophoresis, and the amino acid composition and the terminal residues were determined. The results showed that one or a few related peptides consisting of 7-17 residues were released from the COOH-terminal upon activation. The circular dichroism spectrum of the enzyme suggested that the helical content of the activated enzyme was about 5% less than that of the native enzyme, an indication that the trypsin-activated enzyme has a somewhat looser conformation than the native enzyme. Determination of the fluorescence decay time of the enzyme protein indicated that the tryptophan residue became more exposed to outer environment than that of the native enzyme upon trypsin-activation.

Amino Acids↗
PubMed1980

Active transport of [32P]thiamine diphosphate in Escherichia coli.

Active uptake of [32P]thiamine diphosphate by E. coli was analyzed using an improved method of gel filtration chromatography. The radioactive coenzyme was accumulated without dephosphorylation. From this result it was concluded that thiamine kinase is not involved in the membrane transport of thiamine in E. coli.

Biological Transport, Active↗