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Biomedical subjects

T Kishi

Publications and source records attributed to T Kishi.

At least 181 records · Page 10Linked to original sources
PubMed1982

Effects of thiamin on vitamin B6 synthesis in yeasts.

The effects of exogenous thiamin on the growth yield and vitamin B6 content of 18 strains of yeasts and a few strains of bacteria were examined. The addition of thiamin hardly affected the growth yield of the yeasts tested, except for two strains Saccharomyces uvarum strain 4228 and Saccharomyces uvarum IFO 0751. In contrast, the vitamin B6 content of all the yeasts tested, except Pichia membranaefaciens IFO 0189, decreased markedly in the presence of thiamin. In S. uvarum IFO 1265, the synthesis of vitamin B6 was maximally inhibited by the addition of thiamin (1.5 nmol ml-1) to the growth medium without affecting cell growth, whereas the amounts of cellular vitamin B6 increased in the presence of the thiamin antagonist, pyrithiamin or oxythiamin, at concentrations that did not affect growth. When [4'-14C]pyridoxine. HCl (0.5 micrograms ml-1) was added to the growth medium at least 54% of the added isotope was incorporated into the cells during 24 h incubation. In the presence of thiamin (15 nmol ml-1), at least 32% of the added isotope was incorporated. The metabolism of [4'-14C]pyridoxine. HCl to inactive forms having no vitamin B6 activity was not stimulated by the addition of thiamin. Thus, vitamin B6 synthesis in many yeasts was affected by thiamin, whereas, in bacteria, growth yield and vitamin B6 content were not affected by thiamin.

Bacillus subtilis↗
PubMed1982

Determination of d-methamphetamine in urine after administration of d- or dl-methamphetamine to rats by radioimmunoassay using optically sensitive antiserum.

A radioimmunoassay was developed for the determination of d-methamphetamine in urine. Antiserum to d-methamphetamine was prepared in rabbits by immunization with d-N-4-aminobutylmethamphetamine conjugated with bovine serum albumin. d-1-[3H]-Methamphetamine was used as a labeled compound for radioimmunoassay. The specificity of the antibody against d-methamphetamine was determined by cross-reaction studies with optical isomers of methamphetamine and its analogs. The antibody was specific for d-methamphetamine and exhibited no significant cross-reaction with the l-isomers. This stereoselective assay was applied to determination of d-methamphetamine excreted in urine after oral administration of d- or dl-methamphetamine to rats.

Animals↗
PubMed1981

Microbial conversion of ansamitocin.

Bacteria, actinomycetes, yeasts, and fungi were screened for their ability to modify the structure of ansamitocins, a group of antitumor ansamycin antibiotics. Many strains, mostly actinomycetes, were found to convert ansamitocin P-3 to one or more products. These products, compounds A, B, C, and D, were prepared using Bacillus megaterium IFO 12108, Streptomyces coelicolor IFO 3807, Streptomyces castaneus IFO 13670 and Streptomyces minutiscleroticus IFO 13361, and were identified as 20-O-demethylansamitocin P-3, maytansinol, 15-hydroxyansamitocin P-3 and N-demethylansamitocin P-3, respectively. Other maytansinoids also underwent these microbial conversions.

Bacteria↗
PubMed1981

Sulfazecin, a novel beta-lactam antibiotic of bacterial origin. Isolation and chemical characterization.

Sulfazecin, a new water-soluble acidic antibiotic, which is active against Gram-negative bacteria, was isolated as crystals from the culture broth of Pseudomonas acidophila G-6302 by use of anion exchange resin and activated charcoal. The molecular formula of sulfazecin was determined to be C12H20N4O9S from physicochemical data. The IR and NMR spectra suggested that this antibiotic has a beta-lactam ring, methoxyl and sulfonate groups. On acidic hydrolysis it gave D-alanine and D-glutamic acid. These chemical and physicochemical data indicated that sulfazecin is a new beta-lactam antibiotic.

Chemical Phenomena↗
PubMed1980

Evaluation of an infusion solution enriched with branched chain amino acid in parenteral nutrition of rats.

Nutritional effects of an infusion solution enriched with branched chain amino acids (BCAAs) were investigated with young adult rats. Continuous infusion through a central venous cannula was carried out for 7 days with three kinds of solutions: 1) 21.8% glucose (S-1); 2) 18.6% glucose plus 2.50% amino acids based on human milk pattern (S-2), and 3) 18.6% glucose plus 2.58% amino acids enriched with BCAAs (S-3). Rats received daily 50 ml of the solution, containing 45 kcal and 200 mg N in S-2 and S-3. The body weights of rats in the S-2 and S-3 groups were only slightly reduced, while those of the S-1 group were extremely reduced. The rats were in positive nitrogen balance in the S-2 and S-3 groups on days 2-7. Its value was somewhat, but not significantly, larger in the S-3 group than in the S-2 group. The plasma BCAA levels determined 15 minutes after the end of infusion were higher in the S-3 group than in the S-2 group, but there was no significant difference except for the leucine level. The urinary levels of creatinine and 3-methylhistidine, the plasma levels of urea and glucose, and liver lipid content were similar in the S-2 and S-3 groups. The plasma albumin level was somewhat higher in the S-3 group than in the S-2 group. The present data suggest that an infusion solution enriched with BCAAs served to maintain the normal rats in desirable nutritional status.

Amino Acids↗
PubMed1980

C-19393 S2 and H2, new carbapenem antibiotics. II. isolation and structures.

Two new beta-lactam antibiotics, C-19393 S2 (1) and H2 (2), were isolated from the culture filtrate of Streptomyces griseus subsp. cryophilus nov. subsp. The structures were determined by spectral analysis as shown in Fig. 2. The antibiotics have broad antimicrobial activity and strongly inhibit beta-lactamases. The minor product (2) is more stable than cephalosporin C in aqueous solution.

Anti-Bacterial Agents↗
PubMed1980

Dnacins, new antibiotics II. Isolation and characterization.

Dnacins A1 and B1, new basic antibiotics with strong and broad antibacterial activities, were isolated as dark red or reddish brown needles from the culture broth of Nocardia sp. No. C-14482. The characteristic absorption maxima at 213 nm, 281 or 283 nm and 496 nm in the UV and visible range and other physicochemical properties indicated that dnacins A1 and B1 are novel antibiotics which belong to the group having aminobenzoquinone moieties.

Anti-Bacterial Agents↗