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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 415 records · Page 23Linked to original sources
PubMed1983

Initiation site of deoxyribonucleotide polymerization at the replication origin of the Escherichia coli chromosome.

A new round of chromosomal replication of a temperature-sensitive initiation mutant (dnaC) of Escherichia coli was initiated synchronously by a temperature shift from a nonpermissive to a permissive condition in the presence of arabinosyl cytosine. Increased amounts of nascent DNA fragments with homology for the chromosomal segment containing the replication origin (oriC) were found. The nascent DNA fragments were purified and treated with alkali to hydrolyze putative primer RNA and to expose 5'-hydroxyl DNA ends at the RNA-DNA junctions. The ends were then labeled selectively with T4 polynucleotide kinase and [gamma-32P]ATP at 0 degrees C and the terminally-labeled initiation fragments were purified by hybridization with origin probe DNAs containing one each of the constituent strands of oriC-DNA segment. The 32P-labeled initiation sites were then located at the resolution of single nucleotides in the nucleotide sequence of the oriC segment after cleavage with restriction enzymes. Two initiation sites of DNA synthesis, 37 nucleotides apart, were detected in one of the component strands of the oriC; in other words, in the strand whose 5' to 3' polynucleotide polarity lies counterclockwise on the E. coli genetic map. The results support the involvement of the primer RNA in the initiation of DNA synthesis at the origin of the E. coli genome and suggest that the first initiation event is asymmetric.

Base Sequence↗
PubMed1983

Heme oxygenase activity in liver microsomes of the bullfrog, Rana catesbeiana, and its change during the tadpole development.

Heme oxygenase in the liver microsomes of tadpole and adult bullfrog, Rana catesbeiana, was studied in relation to hemoglobin metabolism during tadpole development. The results obtained are as follows. 1. The specific activity of the enzyme of premetamorphic tadpole liver was comparable to that of adult frog liver. The apparent Km for methemalbumin was about 25 microM for both tadpole and frog enzymes. 2. The enzyme activity was stimulated in vivo by the injection of methemalbumin, phenylhydrazine and triiodothyronine to the animals. 3. A marked increase in the enzyme activity was found in the liver of tadpole during prometamorphic stage and metamorphic climax.

Animals↗
PubMed1983

Prostaglandins E and F in amniotic fluid during stretch-induced cervical softening and labor at term.

An unspecified region of the uterus of 7 healthy pregnant patients at term, not yet in labor, was mechanically distended by extraamniotic application of rubber bougies. In all cases, significant onset of labor was noted within 20 min to 5 h, cervical softening progressed with time, and delivery was achieved within 21 h. Significant elevation of prostaglandin E (PGE) and F (PGF) levels in amniotic fluid was noted with the progress of cervical dilatation. It appears that the release of PGE and PGF is dependent on uterine stretching and/or the subsequently induced uterine contractions. A possible source of the release of PG in the present study was discussed.

Amniotic Fluid↗
PubMed1983

Restriction of host range of xenotropic pseudotype murine sarcoma virus by helper leukemia virus.

We investigated the restriction of the host range to infectivity of MSV by helper leukemia virus in vivo. When newborn SD-rats were inoculated intracerebrally, subcutaneously, intraperitoneally or intramuscularly with xenotropic pseudotype Kirsten MSV, Ki-MSV(BV2), either brain tumors or myogenic sarcomas were induced, depending upon the route of inoculation. However, no tumors developed in SW-Icr mice inoculated with Ki-MSV(BV2) either intracerebrally or intramuscularly at birth. Ecotropic Ki-MSV(Ki-MuLV) induced myogenic sarcomas in mice when inoculated intramuscularly and also induced brain tumors and myogenic sarcomas in rats when inoculated intracerebrally and intramuscularly, respectively. Thus, the host range of pseudotype MSV appeared to depend on a helper leukemia virus.

Animals↗
PubMed1983

Induction of rat brain tumor with xenotropic pseudotype murine sarcoma virus.

The oncogenicity of xenotropic pseudotype Kirsten murine sarcoma virus (MSV) was investigated in Sprague-Dawley rats. When fetal or newborn rats were inoculated intracerebrally with xenotropic pseudotype MSV, brain tumors developed after about one month. Tumors were induced both in the cerebrum and the cerebellum. Histologically, the tumors were predominantly glioblastoma multiforme and hemangioendotheliomas. In cerebellar lesions, malignant transformation of vascular endothelial cells, polycystic areas and numerous giant cells were noted. Proliferation of Purkinje cells was also observed in some of the cerebellar tumors. Inoculation of the same virus by other routes, such as s.c., i.p. and i.m., also caused cerebral and cerebellar tumors. Brain tumors thus induced were transplantable subcutaneously into suckling rats.

Animals↗
PubMed1983

Aculeximycin, a new antibiotic from Streptosporangium albidum. I. Taxonomy of producing organism and fermentation.

A soil isolate of actinomycete, strain TI-1, was found to produce a new antibiotic aculeximycin which killed insects as well as inhibited the growth of bacteria, yeasts and molds in vitro. Yellowish gray colonies on agar media, formation of spherical to oval sporangia at the tip of aerial mycelium and the presence of meso-diaminopimelic acid and madurose in the cell wall ascribed this strain to genus Streptosporangium. From its morphological, cultural and physiological characteristics, the strain was determined to be S. albidum. Production of aculeximycin was carried out by conventional submerged culture: the highest antibiotic titer obtained was 1,250 micrograms/ml.

Actinomycetales↗
PubMed1983

Taxonomy of actinomycetes capable of hydroxylation of ML-236B (compactin).

Three actinomycetes having capability of 3 beta-hydroxylation of ML-236B were isolated from soil samples collected in Australia. Strain SANK 62781 was identified as Nocardia autotrophica. Strain SANK 62881 and strain SANK 62981 were identified as new subspecies of N. autotrophica for which the name N. autotrophica subsp. canberrica and N. autotrophica subsp. amethystina are proposed, respectively. The type strains of N. autotrophica subsp. canberrica and N. autotrophica subsp. amethystina are ATCC 35203 and ATCC 35204.

Anti-Bacterial Agents↗
PubMed1983

Mycoplanecins, novel antimycobacterial antibiotics from Actinoplanes awajinensis subsp. mycoplanecinus subsp. nov. I. Taxonomy of producing organism and fermentation.

Strain No. 41042, an actinomycete isolated from a soil sample, was found to produce 5-azacytidine and new antibiotics, mycoplanecins. Yellowish brown to yellowish orange color of colonies on agar media, formation of globose to subglobose sporangia bearing motile spores and presence of meso- and hydroxy-diaminopimelic acid and glycine in the cell wall ascribed this strain to genus Actinoplanes. From its morphological, cultural and physiological characteristics, this strain was determined to be a new subspecies of Actinoplanes awajinensis and designated as A. awajinensis subsp. mycoplanecinus subsp. nov. Production of mycoplanecins was carried out by conventional submerged culture: the highest antibiotic titer obtained was 145 micrograms/ml.

Actinomycetales↗
PubMed1983

[Bacteriological and clinical evaluation of ceftizoxime in male gonorrheal urethritis].

Forty-one male patients with gonorrheal urethritis were treated with ceftizoxime (CZX) administered concomitantly probenecid at the urological ward of Tokyo Metropolitan Taito Hospital during the period from October, 1982 to February, 1983, and clinically evaluated. Eighty strains of Neisseria gonorrhoeae isolated from the clinical specimens of these patients were bacteriologically studied. Of the 80 strains, 12(15%) were PPNG strains and the other 68 strains were non-PPNG strains. MICs of PCG to the 12 PPNG strains were 3.13 - 25 micrograms/ml and to the 68 non-PPNG strains were 0.0122 - 3.13 micrograms/ml. While MICs of CZX to the PPNG strains were less than or equal to 0.003 - 0.024 micrograms/ml and to the non-PPNG strains were less than or equal to 0.003 - 0.05 micrograms/ml. Those patients with gonorrheal urethritis were given a single 0.5 g intramuscular dose of CZX and a single 1 g oral dose of probenecid. The following clinical findings were obtained: The clinical efficacy rate of 41 cases was 98%; excellent in 24, good in 16, poor in 1 case. All 3 patients with gonorrheal urethritis caused by PPNGs were cured with the treatment. No subjective side effects were found.

Adult↗