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Biomedical subjects

Y Mikami

Publications and source records attributed to Y Mikami.

At least 289 records · Page 16Linked to original sources
PubMed1984

Structure-activity relationships of saframycins.

In vitro antitumor activities of 13 saframycins, including the potent antitumor component, saframycin A, were determined with the highly sensitive established cell line of L1210 mouse leukemia to investigate structure-activity relationships. Saframycins which lack the alpha-cyanoamine group or the alpha-carbinolamine group exhibited much lower cytotoxic activity than saframycin A. The modification of active saframycins either at the C-14 position on the basic skeleton or at the C-25 position on the side chain with bulky substituents resulted in a decrease in cytotoxic activity. These structure-activity relationships corroborated the proposed major mechanism of action for the antitumor activity of saframycin A and supported our proposed model for the saframycin A-DNA adduct.

Animals↗
PubMed1984

Leucinostatins, peptide mycotoxins produced by Paecilomyces lilacinus and their possible roles in fungal infection.

Peptide mycotoxins "leucinostatins" were obtained from the culture strains of Paecilomyces lilacinus, which were isolated both from soil and a case of human oculomycosis. Comparative studies of the symptoms of experimental keratomycosis caused both by the inoculation of P. lilacinus and by direct administration of leucinostatins into the infection model in rabbit suggested the possible role of leucinostatins in the inflammatory response of invaded tissues. Leucinostatin was formerly reported as a single entity. However, in the course of the structural studies, leucinostatin was found to be a complex of two closely related components, and the structures of the both mycotoxins were determined. Both of the mycotoxins possessed high toxicity to experimental animals. The intraperitoneal and oral LD50 values in mice were 1.8 and 5.4 to 6.3 mg/kg by a single administration. Toxicological studies showed that leucinostatins have some potent effects on liver cells after oral administration. It was also found that leucinostatins exhibit strong uncoupling activity on rat liver mitochondrial system.

Animals↗
PubMed1983

Epidemiologic survey of juvenile-onset insulin dependent diabetes mellitus (IDDM) in Hokkaido, Japan, 1973-1981.

An epidemiological survey of juvenile-onset insulin dependent diabetes mellitus (0-15 years) was performed in Hokkaido, Japan, during 1973-1981. The mean annual incidence during the nine year period was 1.26 per 100,000 and showed a significant increasing trend. The prevalence of IDDM at the ages of 0-15 and 6-15 were 7.7 and 11.7 per 100,000 respectively. These figures were much lower than those previously reported in Caucasians. Peaks in incidence were seen from February to April, and a reduction in incidence from July to September. The females showed a bimodal distribution with the peak incidence at 10 to 12 years and with a smaller peak at about 7 years. The males showed a broad single peak at about 10 to 13 years.

Adolescent↗
PubMed1982

Prolactin response to arginine in children with hyperthyroidism and primary hypothyroidism.

Plasma prolactin (PRL) response to arginine was examined in 16 prepubertal and 18 pubertal children with constitutional short stature, 5 patients with hyperthyroidism and 4 patients with primary hypothyroidism. The mean basal concentration of plasma PRL was significantly higher (P less than 0.01) in primary hypothyroidism than in other groups. Arginine infusion elicited significant (P less than 0.05) rises in plasma PRL in all groups. The maximal increment of plasma PRL above the baseline level after arginine stimulation was significantly larger (P less than 0.05) in pubertal than in prepubertal females and was significantly smaller (P less than 0.05) in patients with hyperthyroidism than in age- and sex-matched controls. There was no sex difference in arginine-stimulated PRL secretion. These data suggest that arginine produces a significant increase in plasma PRL and the PRL response to arginine was greater in pubertal than in prepubertal children. Plasma PRL response to arginine is suppressed in children with hyperthyroidism and the basal plasma PRL is markedly elevated in primary hypothyroidism.

Adolescent↗
PubMed1982

Diaminopimelic acid profiles of alkalophilic and alkaline-resistant strains of Actinomycetes.

Twenty alkalophilic actinomycetes with optimum growth pH of 9.0 to 9.5 were isolated. Although these new isolates morphologically closely resembled conventional streptomycetes containing LL-diaminopimelic acid, nine out of 20 isolated contained meso-diaminopimelic acid. Among 420 International Streptomyces Project (ISP) Streptomyces strains tested for their maximum growth pH, only 6 strains grew at pH 11.5. Of these six strains, three strains, S. caeruleus ISP 5103, A. alborubidus ISP 5465 and S. autotrophicus ISP 5011 contained meso-diaminopimelic acid.

Actinomycetales↗
PubMed1982

Factors Affecting Yield and Safety of Protein Production from Cassava by Cephalosporium eichhorniae.

The properties of Cephalosporium eichhorniae 152 (ATCC 38255) affecting protein production from cassava carbohydrate, for use as an animal feed, were studied. This strain is a true thermophile, showing optimum growth at 45 degrees to 47 degrees C, maximum protein yield at 45 degrees C, and no growth at 25 degrees C. It has an optimum pH of about 3.8 and is obligately acidophilic, being unable to sustain growth at pH 6.0 and above in a liquid medium, or pH 7.0 and above on solid media. The optimum growth conditions of pH 3.8 and 45 degrees C were strongly inhibitive to potential contaminants. It rapidly hydrolyzed cassava starch. It did not utilize sucrose, but some (around 16%) of the small sucrose component of cassava was chemically hydrolyzed during the process. Growth with cassava meal (50 g/liter [circa 45 g/liter, glucose equivalent]) was complete in around 20 h, yielding around 22.5 g/liter (dry biomass), containing 41% crude protein (48 to 50% crude protein in the mycelium) and 31% true protein (7.0 g/liter). Resting and germinating spores (10 to 10 per animal) injected by various routes into normal and gamma-irradiated 6-week-old mice and 7-day-old chickens failed to initiate infections.

Journal Article↗
PubMed1981

Microbial Transformation of beta-Ionone and beta-Methylionone.

Aspergillus niger JTS 191 was selected from many microorganisms tested as capable of converting ionones to other compounds having aromas. The individual transformation products from beta-ionone were isolated and identified by comparison with synthetically derived compounds. The major products were (R)-4-hydroxy-beta-ionone and (S)-2-hydroxy-beta-ionone. 2-Oxo-, 4-oxo-, 3,4-dehydro-, 2,3-dehydro-4-oxo-, 3,4-dehydro-2-oxo-, (S)-2-acetoxy-, (R)-4-acetoxy-, and 5,6-epoxy-beta-ionone and 4-(2,3,6-trimethylphenyl)-but-3-en-2-one were also identified. Analogous transformation products of beta-methylionone also were identified. Based on gas-liquid chromatographic analysis during the fermentation, we propose two main oxidative pathways of beta-ionone. The results of this study suggest that these transformations of beta-ionones may be useful as tobacco-flavoring compounds.

Journal Article↗
PubMed1981

Saframycin S, a new saframycin group antibiotic.

Saframycin S, structurally the decyano-saframycin A and biosynthetically the precursor of saframycin A, is a new antibiotic and is assumed to be the active principle for the formation of the antibiotic-DNA complex to manifest its activity. In the present study on the biological activity of saframycin S, the antibiotic showed a marked activity against Ehrlich ascites tumor with the doses of 0.5 to 0.75 mg/kg/day for 10 days, and the rate of 40-day survivors was 80 to 90%. However, this antibiotic was less effective against P388 leukemia than saframycin A at the doses tested. Saframycin S also showed the highest antimicrobial activity, in particular against gram-positive bacteria, among the saframycin group antibiotics identified to date. the LD50 of saframycin S was 3.2 mg/kg (i.p.) for ddY mice. The biological activity and toxicity of saframycin S in relation to its structure were described.

Animals↗