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Biomedical subjects

M Arai

Publications and source records attributed to M Arai.

At least 703 records · Page 39Linked to original sources
PubMed1979

Stereo-specific synthesis of 3-trifluoromethylcephalosporin derivative by microbial acylase.

Cephalosporin acylase (EC 3.5.1.11) obtained from Kluyvera citrophila ATCC 21285 was found to catalyze synthesis of 7-[2-(2-thienyl)acetamido]-3-trifluoromethyl-3-cephem-4-carboxylic acid from methyl thienylacetate and dl-7-amino-3-trifluoromethyl-3-cephem-4-carboxylic acid. The enzymatically-synthesized compound showed [alpha]25 D + 42.7 degrees (c 0.058, MeOH) and its biological activity was about twice as much as that of racemic 7-[2-(2-thienyl)acetamidol]-3-trifluoromethyl-3-cephem-4-carboxylic acid chemicall synthesized. As a result, N-acylation by this enzyme was demonstrated to be asymmetric synthesis.

Amidohydrolases↗
PubMed1979

Effect of dose on urinary bladder carcinogenesis induced in F344 rats by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide.

Because of the utility of the N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) rat model in the study of bladder cancer, the effect of dose on FANFT-induced bladder carcinogenesis was evaluated. Weaning male F344 rats were given FANFT in the diet at doses of 0.1, 0.05, 0.01, 0.005, 0.001, and 0.0005% for 30 weeks and then a control diet for 22 weeks. A control group received only the control diet throughout the experiment. Papillary tumors were present at the higher doses, hyperplasia of various degrees of severly was present at the intermediate doses, and minimal hyperplasia was observed in 4 of 16 rats at the 0.005% dose; no mucosal abnormalities were observed at the two lower doses or in the control group. Bladder epithelium from selected animals was also examined by scanning electron microscopy (SEM) after 10 weeks and again at the end of the experiment. Hyperplastic mucosa with pleomorphic microvilli similar to that previously demonstrated for 0.2% FANFT was observed at 10 weeks in rats fed 0.1% FANFT. Hyperplastic mucosa with pleomorphic microvilli was also observed at 52 weeks in rats fed 0.1% and 0.05% FANFT. Hyperplastic mucosa without pleomorphic microvilli was observed in rats fed 0.01 and 0.005% FANFT. The bladder appeared normal by light microscopy and SEM at the two lower doses and in the control group at both the 10- and 52-week intervals. A dose relationship was thus demonstrated for FANFT-induced bladder carcinogenesis in male F344 rats, and more severe surface changes were observed by SEM as the dose increased.

Animals↗
PubMed1979

Promoting effect of saccharin and DL-tryptophan in urinary bladder carcinogenesis.

The existence of at least two stages in bladder carcinogenesis was evaluated in male Fischer rats using N-[14-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) fed for six weeks at a level of 0.2% of the diet as the initiator. Sodium saccharin and DL-tryptophan were fed at levels of 5 and 2% of the diet, respectively, as possible promoting chemicals, and they were fed either immediately after FANFT administration or after six weeks of FANFT plus six weeks of control diet. All surviving rats were killed at the end of two years. Both chemicals significantly increased the incidence of bladder tumors following FANFT feeding compared to six weeks of FANFT feeding followed by control diet, and the results were similar whether saccharin or tryptophan feeding was started immediately after FANFT feeding was concluded or after a six-week delay. Saccharin was considerably more potent as a promoting agent than was tryptophan, inducing higher incidences of bladder tumors and having a shorter latent period. Long-term administration of FANFT induced a 100% incidence of bladder cancer. Sequential epithelial changes were observed by scanning and transmission electron microscopy as well as by light microscopy. Pleomorphic microvilli were present on the superficial cells of all tumors examined and on the surface cells of hyperplastic bladder epithelium after six weeks of FANFT plus six weeks of saccharin, but not after six weeks of FANFT and six weeks of control diet. Rats fed only saccharin tryptophan, or control diet did not have bladder tumors or pleomorphic microvilli on bladder epithelium. These data suggest that saccharin and tryptophan might act as tumor-promoting agents during bladder carcinogenesis.

Animals↗
PubMed1979

Long-term experiment of maximal non-carcinogenic dose of dimethylnitrosamine for carcinogenesis in rats.

Studies were made on the maximal non-carcinogenic dose of dimethylnitrosamine (DMN) in rats. Groups of Wistar strain rats of both sexes, 6 weeks old, were given standard diet without DMN (group 1), or containing 0.1 ppm DMN (group 2), 1.0 ppm DMN (group 3), or 10 ppm DMN (group 4) for 96 weeks and then sacrificed for hematological, serum-biochemical, and histopathological examinations. After 96 weeks, the weights of the body and main organs in the different groups were not significantly different. The leucocyte count and blood urea-nitrogen (BUN) in group 4 were slightly increased, but other serum findings were not significantly different in different groups. Hepatocellular carcinomas were found in group 3 (1 male and 3 females), but not in group 2. Hemangioendotheliomas of the liver, adrenal adenomas, pituitary adenomas, interstitial cell tumors of the testis, ovarian tumors, and leukemia were also found. Pyelonephritis was found in both experimental and control animals, but no kidney tumors developed with these dose levels of DMN. These results show that on long-term oral administration to rats, 1.0 ppm DMN is the minimum carcinogenic dose, while a level of about 0.1 ppm DMN is non-carcinogenic.

Animals↗
PubMed1978

Globomycin, a new peptide antibiotic with spheroplast-forming activity. I. Taxonomy of producing organisms and fermentation.

A new peptide antibiotic, globomycin, was found to be produced by four different strains of the actinomycetes. They were identified as Streptomyces halstedii No. 13912, Streptoverticillium cinnamoneum No. 15037, Streptomyces neohygroscopicus subsp. globomyceticus No. 15631 and Streptomyces hagronensis No. 17834, respectively. Fermentation of globomycin was conducted by conventional submerged culture for antibiotic production, in which 10 microgram/ml of globomycin was produced by cultivation of S. halstedii No. 13912 for 96 hours at 27 degrees C. Globomycin was named after its activity to form global-shape spheroplasts when Escherichia coli was incubated in the presence of this antibiotic.

Anti-Bacterial Agents↗
PubMed1978

Globomycin, a new peptide antibiotic with spheroplast-forming activity. II. Isolation and physico-chemical and biological characterization.

The peptide antibiotic globomycin was extracted from the culture filtrate of Streptomyces halstedii No. 13912, purified on silica-gel columns and crystallized from acetonitrile to give colorless needles. It is a neutral substance with m.p. of 115 degrees C and a molecular formula of C32H57N5O9. On amino-acid analysis, it gave serine, threonine, glycine and an unidentified amino acid. It is soluble in methanol, ethyl acetate and chloroform but sparingly soluble in water. The antimicrobial spectrum of globomycin revealed its specific activity against Gram-negative bacteria. Formation of spheroplasts was observed when Escherichia coli was grown in the presence of globomycin, indicating inhibition of the bacterial cell wall synthesis as its mode of action.

Anti-Bacterial Agents↗
PubMed1978

Globomycin, a new peptide antibiotic with spheroplast-forming activity. III. Structural determination of globomycin.

The structure of globomycin has been determined by mass, PMR and CMR spectra and by chemical degradation. Globomycin is a new cyclic peptide antibiotic composed of L-serine, L-allo-threonine, glycine, N-methylleucine, L-allo-isoleucine and 3-hydroxy-2-methylnonaic acid. Among these components, L-allo-threonine, L-allo-isoleucine and 3-hydroxy-2-methylnonaic acid are novel components from natural products. A newly developed mass analysis has been introduced for determining the diastereoisomers of allo-threonine.

Amino Acids↗
PubMed1978

New antibiotics, enaminomycins A, B and C. I. Producing organism, fermentation and isolation.

New antibiotics, enaminomycins A, B and C, were found in the culture broth of streptomycete strain No. 13120, which was identified as Streptomyces baarnensis and designated as S. baarnensis No. 13120. Fermentation of enaminomycins were performed by conventional submerged culture in a 30-liter jar fermentor. Isolation of the antibiotics was performed by centrifugation of the culture broth and adsorption of the antibiotics from the supernatant on a column of activated carbon, followed by elution with aqueous acetone. Enaminomycins A, B and C were separated from each other on a column of Sephadex LH-20.

Anti-Bacterial Agents↗
PubMed1978

New antibiotics, enaminomycins A, B and C. II. Physico-chemical and biological properties.

Physico-chemical characterization of enaminomycins revealed that these antibiotics are new members of the epoxy quinone family. From elementary analysis and mass spectroscopic measurements the molecular formulae of enaminomycins A, B and C appear to be C7H5NO5, C10H11N06 and C7H7NO5, respectively. They are very unique in their chemical properties, possessing various functions, such as epoxy, primary amine and carboxylic acid, in their small structural units. Enaminomycin A, the most potent component, has activity against Gram-positive and Gram-negative bacteria and shows cytostatic effect on L1210 mouse leukemia cells in vitro, but enaminomycins B and C are only weakly active against Gram-positive and Gram-negative bacteria.

Animals↗
PubMed1978

New antibiotics, enaminomycins A, B and C. III. The structures of enaminomycins A, B and C.

The structures of enaminomycins A and B were determined by their physico-chemical properties and X-ray crystallographic analyses to be 4-amino-2,5-dioxo-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid and 2-oxo-4-amino-5-hydroxy-5-acetonyl-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid, respectively. The structure of enaminomycin C was also determined by the analysis of NMR spectrum and other physico-chemical properties to be 2-oxo-4-amino-5-hydroxy-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid.

Anti-Bacterial Agents↗
PubMed1978

Production, isolation and chemical characterization of mimosamycin.

A procedure is described for the large-scale production of mimosamycin, a satellite antibiotic found in the culture filtrate of Streptomyces lavendulae No. 314. The 1H and 13C NMR, and mass spectroscopic data, are explained in terms of the structure of mimosamycin.

Anti-Bacterial Agents↗
PubMed1978

The influence of N-[4-(5-nitro-2-Furyl)-2-thiazolyl]formamide and phenacetin on the immune status in male Fischer rats.

The effect of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANTF) and phenacetin on the immune status of Fischer rats was determined utilizing the spleen plaque and phytohemagglutinin blastogenesis assays 6, 10, and 15 weeks after administration at doses of 0.2 per cent and 0.535 per cent, respectively. Azathioprine (0.02 per cent of the diet) was tested as a known immunosuppressive chemical for comparison, and a negative control group, fed a control diet without added chemicals, was also tested. Immunosuppression was shown in the rats receiving azathioprine at all times by both assays, whereas in FANFT-fed rats immunosuppression was greater than in the control group (not statistically significant). Results from rats fed phenacetin were not significantly different than those of the control group. These results show that immunosuppression does not occur in rats administered phenacetin for up to 15 weeks, nor in FANFT-induced bladder carcinogenesis at the time of reversible bladder mucosal hyperplasia (6 weeks), or when the mucosal lesions have become irreversible, non-invasive carcinomas (10 and 15 weeks).

Animals↗