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Biomedical subjects

Y Okami

Publications and source records attributed to Y Okami.

At least 73 records · Page 4Linked to original sources
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. I. The use of plasmid profiles in screening antibiotic-producing streptomycetes.

Plasmid profiles were used to screen streptomycetes for production of new antibiotics. Among about 100 strains isolated from sea muds, an isolate designated SS-939 was revealed to harbor several plasmids of different sizes, and to produce istamycins, new aminoglycoside antibiotics. Based on the characteristics of the strain, a new Streptomyces species is proposed: S. tenjimariensis.

Aminoglycosides↗
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. II. Possible involvement of plasmid in istamycin production.

Acriflavine treatment of an istamycin-producing Streptomyces tenjimariensis strain designated SS-939 resulted in a high frequency of isolates with reduced istamycin production. Some of these were shown to have lost a particular plasmid present in the parent strain. Istamycin production by these isolates was largely restored by the addition of 2-deoxystreptamine (DOS) to the medium whereas the effect of DOS was small in the strain SS-939. Sodium palmitate also stimulated production, especially when added together with DOS. These stimulative effects by DOS and palmitate, however, were not exhibited in the presence of glucose (1.0%).

Acridines↗
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. III. Nutritional effects on istamycin production and additional chemical and biological properties of istamycins.

Streptomyces tenjimariensis SS-939 produced istamycins in a medium containing starch as the carbon source and soy bean meal as the nitrogen source. Istamycin production decreased substantially when starch was substituted with mono- or di- saccharides such as glucose, glycerol and maltose. A marked decrease of istamycin production was also observed when a rapidly used nitrogen source such as yeast extract, peptone or casamino acid was employed instead of soy bean meal. Addition of palmitate at a concentration of 0.2% doubled istamycin production. Istamycins A and B were found to be as active as fortimicin A and sporaricin A against Gram-positive and Gram-negative bacteria including aminoglycoside-resistant strains.

Aminoglycosides↗
PubMed1977

Structure of aplasmomycin.

A new antibiotic, aplasmomycin, was isolated from a broth cultivated with a marine isolate of actinomycete, and inhibits Gram-positive bacteria in vitro and Plasmodium berghei in vivo. It is a natural ionophore and the structure of the Ag-salt was solved by an X-ray crystallographic analysis. It has symmetric structure having boron in the centre of the molecule.

Anti-Bacterial Agents↗
PubMed1976

Studies on marine microorganisms. V. A new antibiotic, aplasmomycin, produced by a streptomycete isolated from shallow sea mud.

A new antibiotic, aplasmomycin, which inhibits growth of Gram-positive bacteria including myobacteria in vitro, and plasmodia in vivo was obtained from a strain of Streptomyces griseus isolated from shallow sea sediment in Sagami Bay. The antibiotic forms colorless needle-like crystals and has a molecular formula of C41H60O14Na. Based on its physical and chemical properties, aplasmomycin was concluded to be a new antibiotic. The antibiotic was produced in selected media devised to relate to a marine environment.

Animals↗
PubMed1975

Studies on marine microorganisms. IV. A new antibiotic SS-228 Y produced by Chainia isolated from shallow sea mud.

A new antibiotic named SS-228 Y, which inhibits growth of Gram-positive bacteria, Ehrlich carcinoma in mice, and dopamine-beta-hydroxylase, was obtained from a species of Chainia isolated from shallow sea mud in Sagami Bay. It was yellowish brown powder having the molecular formula C19H1406. From the physical and chemical properties, SS-228 Y was concluded to b a new antibiotic having structure of peri-hydroxyquinone moiety.

Actinomycetales↗
PubMed1975

Biological studies of amiclenomycin.

The action of amiclenomycin (AM) in inhibiting growth of microorganisms is specific against mycobacteria in vitro, but the antibiotic does not show a therapeutic effect against tubercle bacilli in vivo. The action of AM is reversed by biotin, desthiobiotin (DTB) and 7,8-diaminopelargonic acid (DAPA), but not by 7-keto-8-aminopelargonic acid (KAPA), pimelic acid and glutaric acid. In the presence of AM, cultures of Mycobacterium smegmatis and Bacillus sphaericus accumulated KAPA, whereas the formation of DTB decreased. Therefore, AM is thought to inhibit KAPA-DAPA transamination in biotin biosynthesis. In M. smegmatic and B. sphaericus the conversions of KAPA to DAPA and of DTB to biotin were rate limiting in biotin synthesis. Accordingly, the synergistic antibiotic activity of AM, inhibiting the former, and actithiazic acid, inhibiting the latter reaction, would be simply explained.

Amino Acids, Diamino↗
PubMed1975

Studies of the mode of action of amiclenomycin.

Amiclenomycin (AM) was found to be a strong inhibitor of KAPA-DAPA aminotransferase of Brevibacterium divaricatum. This transamination was suggested to follow Ping Pong Bi Bi mechanism. Inhibition of this transamination by AM is of a noncompetitive type in a Lineweaver-Burk plot of initial velocity, but not in a Dixon plot. The activity of KAPA-DAPA aminotransferase drops abruptly after preincubation with AM, but its activity is restored by dialysis against 10 mM potassium phosphate buffer (pH 7.0). Inhibition by AM is decreased by an increase of KAPA in the reaction mixture, but not by an increase of S-adenosyl-L-methionine (SAM) or pyridoxal-5'-phosphate (PALP). These facts indicate that AM exerts its inhibitory action against KAPA-DAPA aminotransferase by binding to the enzyme, probably to the KAPA-DAPA binding site.

Amino Acids↗