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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 559 records · Page 31Linked to original sources
PubMed1997

[Changes in tissue and blood polyamines during N-butyl-N-(4-hydroxybutyl) nitrosamine-induced bladder carcinogenesis in rats].

BACKGROUND: Polyamine are recognized as cell growth factors. We studied in order to determine whether alterations in the levels of tissue and blood polyamines were useful biochemical markers for bladder tumor. METHODS: The concentrations of three polyamines, diamine, spermidine and spermine, in urinary bladder and blood were determined during N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced bladder carcinogenesis in male F344 rats. At 5 weeks of age, rats were given 0.05% BBN in the drinking water for 20 weeks. RESULTS: BBN induced bladder hyperplasia in 4 of 5 rats at 8 weeks, papillomas in 2 of 5 rats at 12 weeks, and transitional cell carcinoma in all the rats by 20 weeks. The levels of total polyamine in both bladder and blood of the rats during 12-20 weeks were significantly higher than those of the control animals given water alone. The elevation of total polyamine was mainly due to the increase of spermidine of the three polyamines, which was coincident with the incidence of bladder tumors. CONCLUSION: The results indicated that the polyamines are excellent biochemical markers for bladder tumors.

Animals↗
PubMed1997

[Changes in tissue and blood polyamine levels following chemotherapy in rats with urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl) nitosamine in rats].

BACKGROUND: Polyamines are recognized as cell growth factors. We attempted to determine whether alterations in the levels of tissue and blood polyamines were useful biochemical makers for monitoring the efficacy of the chemotherapy for bladder tumors. METHODS: The concentrations of three polyamines of diamine, spermidine and spermine in urinary bladder and blood were determined in male F344 rats with urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN), following chemotherapy with cisplatin, methotrexate and pirarubicin. RESULTS: Bladder carcinoma was observed in 5 of 20 rats of the chemotherapeutic group, and 16 of 20 rats of the control group given saline alone. The levels of spermidine, spermine and total polyamine in both bladder and blood of the treated rats were significantly lower than those of the control rats. CONCLUSION: The study suggested that the levels of tissue and blood polyamines could be used as biochemical markers for monitoring the efficacy of the chemotherapy for bladder tumors.

Animals↗
PubMed1997

Resormycin, a novel herbicidal and antifungal antibiotic produced by a strain of Streptomyces platensis. I. Taxonomy, production, isolation and biological properties.

Resormycin, a novel herbicidal and antifungal antibiotic, was isolated from the cultured broth of streptomycete strain. The strain was isolated from a soil collected at Yokohama-shi, Kanagawa Prefecture, Japan, and identified as Streptomyces platensis MJ953-SF5. Resormycin was purified by active charcol, Amberlite IRC-50, Amberlite CG-50 and Sephadex LH-20 column chromatographies. Resormycin markedly inhibited the growth of monocotyledonous and dicotyledonous weed. The antibiotic showed antimicrobial activity against phytopathogenic fungi.

Antifungal Agents↗
PubMed1997

Resormycin, a novel herbicidal and antifungal antibiotic produced by a strain of Streptomyces platensis. II. Structure elucidation of resormycin.

A novel herbicidal antibiotic, resormycin, was isolated from the culture broth of Streptomyces platensis MJ953-SF5. The structure of resormycin is determined to be (2Z)-2-N-[2N-[(3S)-3,6-diaminoheptanoyl]-(2S)-3-hydroxyva lyl]amino-3- (4-chloro-3,5-dihydroxy)phenylpropenoic acid by spectroscopic analyses, degradation studies and X-ray crystallography.

Antifungal Agents↗
PubMed1997

Mode of antifungal action of benanomicin A in Saccharomyces cerevisiae.

The mechanism of fungitoxic action of an antifungal antibiotic benanomicin A was studied with intact cells and protoplasts of Saccharomyces cerevisiae as well as with its enzymic preparations. The results obtained are summarized as follows: (1) benanomicin A at relatively high concentrations (almost equal to MIC) was fungicidal and disrupted the cell permeability barrier, inducing leakage of intracellular K+ and ATP in growing cells, while the antibiotic had none of these effects in non-growing cells; (2) no biosynthesis of any of several major cellular constituents in yeast cells was inhibited markedly or selectively enough to explain its fungitoxic activity; (3) whereas benanomicin A induced lysis of metabolically active yeast protoplasts incubated in the presence of glucose, inactive yeast protoplasts incubated without glucose were refractory to the lytic action of the antibiotic; (4) osmotically shocked yeast cells became feasible to the cidal action of benanomicin A; (5) benanomicin A substantially inhibited uptake of 6-deoxy-glucose by yeast cells; (6) liposomes composed of phospholipids and cholesterol were not susceptible to benanomicin A; and (7) benanomicin A inhibited in vitro activity of H(+)-ATPase from yeast cell membranes to a greater extent than that for H(+)-ATPase from yeast mitochondria or H(+)-ATPase from yeast vacuolar membranes. Based on these and our previous data that benanomicin A preferentially binds to mannan or mannoproteins constituting the cell wall and cell membrane of yeasts, such binding of the antibiotic is suggested to deteriorate the normal structure and function of those cell membranes of yeasts which are in a growing or metabolically active state, ultimately leading to cell death.

Adenosine Triphosphatases↗
PubMed1997

Pyralomicins, novel antibiotics from Microtetraspora spiralis. IV. Absolute configuration.

The absolute configurations of pyralomicin la and pyralomicin 2a were determined by X-ray crystallographic analyses of crystalline 7'-O-p-bromobenzoylpyralomicin 1a and 2'-O-p-bromobenzoylpyralomicin 2a derived from pyralomicin 1a and pyralomicin 2a using anomalous scattering of the bromine atom. The absolute configurations of pyralomicins 1b approximately 1d and 2b approximately 2e were suggested to be the same as pyralomicin 1a and pyralomicin 2a, respectively, by comparing the circular dichroism spectra.

Actinomycetales↗
PubMed1997

A synthetic approach to benanomicin A. 2. Synthesis of the substituted 5,6-dihydrobenzo[a]naphthacenequinone.

The key intermediate tri-substituted alpha-tetralone (8) has been synthesized, either via tandem Michael addition-Dieckmann condensation reaction between dienolate and methyl crotonate in a low yield or via Barton's radical decarboxylation of diester (9) without 4-dimethylaminopyridine in 75% yield, and applied to the synthesis of the substituted 5,6-dihydrobenzo[a]naphthacenequinone.

Anthracyclines↗
PubMed1997

Selective deoxygenation and O-methylation of benanomicin A: synthesis of 9-deoxy-, 9-O-methyl- and 14-O-methylbenanomicin A.

The selective modifications of phenolic hydroxy groups in the chromophore of benanomicin A are described. Hydride reduction of 9-O-tosylate with sodium borohydride/nickel chloride led to 9-deoxybenanomicin A. Methylation of 1-O-diphenylmethylbenanomicin A diphenylmethyl ester with sodium hydride/iodomethane gave 9-O-methyl derivative and with Hünig's base/diazotrimethylsilylmethane afforded the 14-O-methyl derivative. These compounds showed the diminished activity against fungi.

Anthracyclines↗
PubMed1997

Epoxyquinomicins A, B, C and D, new antibiotics from Amycolatopsis. I. Taxonomy, fermentation, isolation and antimicrobial activities.

A new structural class of the antibiotic, epoxyquinomicins A, B, C and D were isolated from the culture broth of the strain MK299-95F4, which was related to Amycolatopsis sulphurea. Antimicrobial activity of epoxyquinomicins A and B were weak against Gram-positive bacteria, and epoxyquinomicins C and D showed almost no antimicrobial activity and no cytotoxicity. All these antibiotics showed improvement of collagen induced arthritis in vivo.

Actinobacteria↗
PubMed1997

Epoxyquinomicins A, B, C and D, new antibiotics from Amycolatopsis. II. Effect on type II collagen-induced arthritis in mice.

The anti-arthritic effects of epoxyquinomicins on type II collagen-induced arthritis in DBA/1J mice were examined. Prophylactic treatment with epoxyquinomicins A, B, C and D (1-4 mg/kg) had potent inhibitory effects on type II collagen-induced arthritis. In contrast to nonsteroidal anti-inflammatory drugs (NSAIDs), epoxyquinomicin C (1-30 mg/kg) had neither an anti-inflammatory effect on carrageenan-induced paw edema in rats nor an analgesic effect on acetic acid-induced writhing in mice. These results suggest that the mode of action of epoxyquinomicins is different from that of NSAIDs and that epoxyquinomicins may become useful drugs for the treatment of rheumatoid arthritis.

Actinobacteria↗
PubMed1997

Epoxyquinomicins A, B, C and D, new antibiotics from Amycolatopsis. III. Physico-chemical properties and structure determination.

The structures of epoxyquinomicins A (1), B (2), C (3) and D (4) were determined by spectroscopic studies. Compound 1 was determined to be (5R,6S)-2-(3-chloro-2-hydroxybenzoylamino)-5-hydroxymethyl-5,6-epo xy- 2-cyclohexene-1,4-dione. Compound 2 was revealed to be the dechlorinated derivative of 1. Compounds 3 and 4 were determined to be the reduced derivative of 2 and 1, respectively.

Actinobacteria↗