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Biomedical subjects

M Arisawa

Publications and source records attributed to M Arisawa.

At least 163 records · Page 9Linked to original sources
PubMed1982

In vitro effect of LH-releasing factor on the content of cyclic cytidine 3' 5' monophosphate (c-CMP) in the rat anterior pituitary.

The effect of LH-RF on pituitary content of cyclic cytidine 3' 5' monophosphate (c-CMP), one of the newly detected cyclic nucleotides, was examined by the RIA procedure. In results showed that the pituitary content of c-CMP was lower than in various other organs of the rat. When incubated in vitro in the presence of 0.5 ng LH-RF/ml incubation medium, c-CMP content of the anterior pituitaries was reduced slightly, but the difference was not statistically significant when compared with the controls. No difference in c-CMP content was observed between the controls and the 5 ng LH-RF/ml group. C-CMP content in the rat anterior pituitary tissue did not change significantly during an in vitro time-course study (5, 15, and 30 min.) in the presence of 5 ng LH-RF/ml. In contrast, c-AMP content of the pituitary was significantly (P less than 0.05) elevated by the stimulation of 5 ng of LH-RF/ml at a 15 minutes of incubation. These data suggest that c-CMP content, unlike c-AMP, might not be changed significantly by hypothalamic gonadotropin releasing hormone.

Animals↗
PubMed1982

6-Acetylmethylenepenicillanic acid (Ro 15-1903), a potent beta-lactamase inhibitor. I. Inhibition of chromosomally and R-factor-mediated beta-lactamases.

6-Acetylmethylenepenicillanic acid (Ro 15-1903) was seen to be a powerful inhibitor of various beta-lactamases. Nearly all of the chromosomally and R-factor-mediated beta-lactamases which were studied were inhibited at much lower concentrations than required with clavulanic acid or sulbactam. Ro 15-1903 protected beta-lactamase-labile penicillins and cephalosporins from hydrolysis. The compound itself was stable against hydrolysis and inhibition of beta-lactamase was irreversible.

Bacteria↗
PubMed1982

6-Acetylmethylenepenicillanic acid (Ro 15-1903), a potent beta-lactamase inhibitor. II. Antibacterial properties.

The beta-lactamase inhibitor Ro 15-1903 showed low affinity for penicillin binding proteins (PBPs) of Escherichia coli. When used as a single compound, it displayed no substantial antibacterial activity but in combination with ampicillin, it was similar to clavulanic acid in conferring activity against ampicillin-resistant strains. Some synergy between Ro 15-1903 and piperacillin was found against high inocula of Pseudomonas aeruginosa. Ro 15-1903 markedly enhanced the activity of ceftriaxone against Bacteroides fragilis. In keeping with the in vitro findings, the combination Ro 15-1903 and ampicillin protected mice against systemic infections with beta-lactamase-producing strains of Staphylococcus aureus, Klebsiella pneumoniae and Proteus sp. but not against those with Enterobacter cloacae, Serratia marcescens, and E. coli producing either chromosomally mediated beta-lactamase of type I or plasmid-mediated beta-lactamase of type TEM.

Animals↗
PubMed1979

Alafosfalin, a new inhibitor of cell wall biosynthesis: in vitro activity against urinary isolates in Japan and potentiation with beta-lactams.

A new phosphonopeptide, alafosfalin, was evaluated for in vitro antibacterial activity and for synergism with beta-lactams, using 475 Japanese clinical isolates from urinary tract infections. Alafosfalin was found to be highly active against Escherichia coli and moderately active against Serratia, Klebsiella, Enterobacter, and Citrobacter, but less active against gram-positive organisms than were beta-lactams such as cephazolin or ampicillin and inactive against indole-positive Proteus, Pseudomonas, and Acinetobacter. Potentiation with the two beta-lactams (fractional inhibitory concentration less than or equal to 0.5) was found in 10 to 40% of susceptible strains in 4:1 and 1:4 combinations, and to a lesser extent in those species or genera that were insensitive to alafosfalin alone. No cross resistance was seen between alafosfalin and the beta-lactams or any other commonly used antibacterial agents tested. Effect on selected ampicillin-resistant strains, differential sensitivity to alafosfalin among resistant strains of various types, and sensitivity of alafosfalin-insensitive E. coli and Klebsiella to other antibiotics are also discussed.

Alanine↗
PubMed1978

Differential mutagenicity of reaction products of various pyrazolones with nitrite.

Four pyrazolones in frequent use, i.e. antipyrine (AP), aminopyrine (AMP), sulpyrine (SP) and isopropylantipyrine (IPA), were compared for their reactivity with nitrite and for the in vitro mutagenicity of their reaction products by Ames' reversion tests. In various acidic solutions at 37 degrees C, AP, AMP and SP were found to react easily with nitrite and yield various products including dimethylnitrosamine (DMNA) and 4-nitrosoantipyrine (4-NAP) in the cases of AMP and AP, respectively. When tested with Salmonella typhimurium TA100 and TA98 after lyophilization, the reaction products of AP (AP-N) were found to be mutagenic in both strains, while products of AMP and SP (AMP-N and SP-N) were mutagenic only in TA100. The presence of unknown ultimate mutagens, other than DMNA and 4-NAP, were evidenced in AP-N, AMP-N and SP-N. Incubation with S-9 mixture did not affect the mutagenicity of SP-N and decreased that of AP-N and AMP-N. In clear contrast to AP, AMP and SP, it was found that IPA remained essentially intact upon reaction with nitrite. No mutagenicity was detected with the reaction mixture (IPA-N) in either strain.

Aminopyrine↗
PubMed1975

Simplified assay for concanavalin A-dependent bacterial agglutination by using cell surface mutants.

Two cell surface mutants of Escherichia coli isolated through supersensitivity to sodium dodecyl sulfate were found to be agglutinated by concanavalin A in the intact rod form. By using these strains, the assay method for the concanavalin A-dependent agglutination was greatly simplified since neither spheroplast formation nor protease treatment is needed. This rod cell agglutination was characterized and applied for a semiquantitative determination of the amount of bound concanavalin A.

Agglutination↗