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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 397 records · Page 22Linked to original sources
PubMed1985

[Fetal maturation and amniotic fluid levels of catecholamines and their metabolites].

Phosphatidylglycerol (PG), a phospholipid closely associated with fetal lung maturity, appears in the amniotic fluid (AF) of complicated pregnant women much earlier than it usually increases during uneventful pregnancy. In this study, AF PG levels, measured by an enzymatic method, were correlated with AF concentrations of catecholamines (CAT) and the deaminated metabolites of dopamine (3,4-dihydroxyphenylacetic acid; DOPAC) and norepinephrine (3,4-dihydroxyphenylglycol; DOPEG), all of which were determined by radioenzymatic assay. AF concentrations of CAT increased with the advance of gestation especially after 36 weeks of gestation, when clinically apparent fetal distress was not present. Three to four fold higher levels of DOPAC and DOPEG over their parent CAT were found in AF. Even prior to 37 weeks of gestation, high concentrations of CAT were found in the pregnancies complicated with fetal distress, and significant correlation was noted for PG versus dopamine (p less than 0.005), norepinephrine (p less than 0.05) epinephrine (p less than 0.02) and DOPEG (p less than 0.05), but not DOPAC. Such a correlation was not observed after 37 weeks of gestation. These findings suggest that fetal CAT plays a primary role in developing fetal lung maturation and that AF PG and CAT increase as a response to chronic distress, only before 37 weeks of gestation.

Adrenal Glands↗
PubMed1984

The identification and characterization of protein kinase C activity in fetal membranes.

Protein kinase C activity was demonstrated in cytosolic fractions prepared from human amnion and decidua vera tissues. The enzyme has been partially purified and was found to be glycerophospholipid-dependent. Phosphatidylserine was most active in the stimulation of protein kinase C. Ca2+ was also required for the expression of the enzyme activity. In the presence of unsaturated diacylglycerols, maximum activation of protein kinase C was observed at suboptimal concentrations of Ca2+. A possible role of phospholipid-dependent protein kinase C in the regulation of arachidonic acid release in this tissue is discussed.

Amnion↗
PubMed1984

Effect of E-64, a thiol protease inhibitor, on antibody formation in mice.

E-64, L-trans-epoxysuccinyl-leucylamido (4-guanidino) butane, a specific inhibitor of thiol proteases originally isolated from a culture broth of fungi, and its synthetic analogues, were examined for immune responses to the splenocytes of BDF1 mice. In the cultures of 2-day-primed splenocytes of the mice, E-64 and its close analogues, increased the number of direct splenic hemolytic plaque forming cells (PFC). In addition, it was demonstrated that E-64 enhanced the PFC responses in the mice. These results suggested that some thiol proteases might be involved in the immune response process in mice.

Animals↗
PubMed1984

Function of RNase H in DNA replication revealed by RNase H defective mutants of Escherichia coli.

Escherichia coli rnh mutants were isolated using localized mutagenesis and selective measurements of RNase H activity in mutagenized cell extracts with [3H]poly(rC) X poly(dG) as substrate. RNase H activity in extracts of one mutant, ON152 (rnh-91), was undetectable (less than 0.05% of that of wild-type cells). This mutant formed small colonies at 43 degrees C. At this temperature, accumulation of nascent fragments was more prominent in the rnh-91 X polA4113 double mutant than in the polA4113 mutant; however, no accumulation was found in the rnh single mutant at 43 degrees C. Unlike the 1-3 nucleotide primer RNA found on nascent fragments of polA4113 cells, primers from the rnh-91 X polA4113 cells ranged from one to about ten bases. These results suggest that the 5' leads to 3' exonuclease activity of DNA polymerase I plays a major role in removal of primer RNA and that RNase H functions in an auxiliary role, excising the 5'-portion of longer primers. The rnh mutant supports replication of ColE1-type plasmids. A possible mechanism of replication of such plasmids in rnh mutants and a role of RNase H in the initiation of chromosomal replication are discussed.

Coliphages↗
PubMed1984

Ossification of the paravertebral ligaments: a frequent complication of hypoparathyroidism.

Various forms of paravertebral ligamentous ossification (PVLO) were detected radiologically in 9 (53%) of 17 consecutive patients with hypoparathyroidism. A significant correlation was found between the period during which the patient was untreated and the incidence of ossification. Serum levels of calcium, phosphate, and their ionic product appeared not to influence the incidence. All the patients with PVLO exhibited evidence of ectopic calcification. The fact that ectopic ossification, which is histologically distinct from ectopic calcification, is frequently associated with hypoparathyroidism suggests that similar pathogenetic mechanisms are responsible for the development of these two conditions. The high incidence of PVLO in hypoparathyroid patients in this study may explain some of the neurologic findings in hypoparathyroidism that have been hard to explain simply on the basis of altered neuromuscular excitability.

Adult↗
PubMed1984

Escherichia coli mutants suppressing replication-defective mutations of the ColE1 plasmid.

Mutants of Escherichia coli K-12 have been isolated that suppress cer mutants, ColE1 mutants that are unable to replicate as the plasmid. These host suppressors were designated her, for host factor affecting ColE1 replication. Each her suppressor showed a characteristic pattern of suppression depending on the cer mutation used for selecting the mutant bacteria. One of the suppressors, named herA, that suppressed cer6, a single-base-pair alteration 160 base pairs upstream of the ColE1 replication origin, was genetically identified as an alteration of the rnh gene (RNase H). HerA was recessive to its wild-type allele. RNase H activity of herA cell extracts was defective. Conversely, rnh mutants that were isolated independently of ColE1 replication supported replication of cer6 DNA. Some rnh mutants manifested the HerA phenotype only above a certain transition temperature, and their RNase H activity was found to be temperature sensitive. Therefore, replication of cer6 DNA in vivo is sensitive to RNase H activity. Under the conditions that suppressed cer6, the wild-type colE1 replicon replicated normally. Then, ColE1 replication in vivo proceeds in the absence of RNase H activity, which has been shown to be required for in vitro replication of the DNA.

Bacteriocin Plasmids↗
PubMed1984

Effect of E-64, thiol protease inhibitor, on the secondary anti-SRBC response in vitro.

E-64, L-trans-epoxysuccinyl- leucylamido (4-guanidino) butane, a specific inhibitor of thiol proteases originally isolated from the culture of a fungus, was examined in connection with the immune responses to the splenocytes of mice. In cultures of C3H/He mouse splenocytes, E-64 and its analogues showed mitogenic activity, and some of them enhanced the lymphocyte blast transformation induced by a suboptimal concentration of concanavalin A. E-64 caused a significant suppressive effect on the secondary anti-SRBC responses when 7- or 14-day-primed BDF1 mouse splenocytes were cultured with SRBC, while it induced no effect on cultured splenocytes either from mice treated with cyclophosphamide, from mice sensitized with dinitrophenyl-Ficoll. The results with E-64 and its close analogues revealed that their effects on the immune response roughly correlated with their inhibitory activity against thiol protease. These results suggest that a thiol protease might be involved in the process of secondary immune response in mouse splenocytes.

Animals↗
PubMed1984

The effect of low dose Ara-C in acute nonlymphoblastic leukaemias and atypical leukaemia.

Nine patients with nonlymphocytic leukaemia and one patient with refractory anaemia with excess of blasts (RAEB) were treated subcutaneously with Ara-C at a low dose of 10 mg/m2/12 h; complete remission was obtained in seven patients. In all cases severe pancytopenia was observed during treatment. We measured the concentration of Ara-C in serum, and found that the maximum concentration reached a peak (52-132 ng/ml; mean 84.2 ng/ml) at 15 min following injection. These concentrations can be considered sufficient to inhibit DNA synthesis. Primary short-term culture of human leukaemic cells with low dose Ara-C was also performed, and differentiation of leukaemic cells was observed for several types of leukaemic cells. The in vitro findings corresponded to the observed clinical effects. From the above results, the action of low dose Ara-C may have resulted from a combination of two different mechanisms, its cytostatic effect and its differentiation-inducing effect.

Adult↗
PubMed1984

Discontinuous DNA replication of Drosophila melanogaster is primed by octaribonucleotide primer.

To investigate the precise structure of eucaryotic primer RNA made in vivo, short DNA chains isolated from nuclei of Drosophila melanogaster embryos were analyzed. Post-labeling of 5' ends of short DNA chains with polynucleotide kinase and [gamma-32P]ATP revealed that 7% of the DNA fragments were covalently linked with mono- to octaribonucleotide primers at their 5' ends. Octaribonucleotides, the major component (ca. 30%), formed the cap structure in the reaction with vaccinia guanylyltransferase and [alpha-32P]GTP, indicating that they were the intact primer RNA with tri- (or di-) phosphate termini, and the shorter ribooligomers were degradation intermediates. The intact primers started with purine (A/G ratio, 4:1), and the starting few ribonucleotide residues were rich in A.

Animals↗
PubMed1984

Immunopharmacologic profiles of a thiol protease inhibitor, L-trans-dicyclohexyl epoxysuccinate.

Ep-1, L-trans-Dicyclohexyl epoxysuccinate, is a synthetic and specific inhibitor of thiol proteases. The effects of this inhibitor on some immunological parameters were examined in normal and immunity-impaired mice and rats. In the cultures of splenocytes obtained from the mice treated with Ep-1, it enhanced the lymphocyte blast transformation induced by both suboptimal and optimal concentrations of concanavalin A (Con A) and Lens culinaris (LC). The in vivo administration of Ep-1 caused a depression of the plaque forming cells (PFC) for sheep red blood cell (SRBC) and enhanced the delayed-type hypersensitivity (DTH) for bovine serum albumin (BSA) as well as mixed lymphocytes cultures (MLC). Furthermore, Ep-1 demonstrated a preventive effect on adjuvant arthritic rats. The relevance of immunological regulation and the mode of action of Ep-1 as a thiol protease inhibitor are discussed in these findings.

Adjuvants, Immunologic↗
PubMed1984

[Bacteriological and clinical evaluation of the effect of azthreonam on gonorrheal urethritis in man].

Thirty male patients with gonorrheal urethritis were treated with azthreonam at the urological ward of Tokyo Metropolitan Taito Hospital during the period from January to March, 1984, and clinically evaluated. Sixty-one strains of Neisseria gonorrhoeae isolated from the clinical specimens including those of the patients were bacteriologically studied. Of the 61 strains, 9 (15%) were PPNG strains and the other 52 strains were non-PPNG strains. MICs of PCG to the 9 PPNG strains were 3.13--50 micrograms/ml and to the 52 non-PPNG strains were 0.024--3.13 micrograms/ml. While MICs of azthreonam to the PPNG strains were 0.024--0.20 micrograms/ml and to the non-PPNG strains were 0.0122--0.78 micrograms/ml. Those patients with gonorrheal urethritis were given a single 1 g intramuscular dose of azthreonam. The following clinical findings were obtained: The clinical efficacy rate of 30 cases was 100%; excellent in 16, good in 14 cases. All 2 patients with gonorrheal urethritis caused by PPNGs were cured with the treatment. No subjective side effects were found.

Adult↗
PubMed1984

Propylthiouracil-induced diffuse interstitial pneumonitis.

Cough productive of sputum, exertional dyspnea, and hypoxemia developed in two patients with Graves' disease after six months (patient 1) or three weeks (patient 2) of treatment with propylthiouracil, 300 mg/day. Chest roentgenograms and transbronchial lung biopsy specimens revealed diffuse interstitial pneumonitis. Lymphocyte transformation by phytohemagglutinin was highly stimulated by propylthiouracil. Symptoms and signs improved after cessation of the drug therapy and administration of prednisolone acetate. These cases represent the first report of a complication of diffuse interstitial pneumonitis induced by propylthiouracil.

Aged↗
PubMed1983

Site selection and structure of DNA-linked RNA primers synthesized by the primosome in phage phi X174 DNA replication in vitro.

Synthesis of a complementary strand on the circular viral (+)-DNA of phage phiX174, coated with single-stranded DNA binding protein, is primed by the synthesis of an oligonucleotide by the primosome. Processive primosome movement on the lagging strand with the replication fork was proposed as a model for the discontinuous portion of Escherichia coli chromosome replication (Arai, K. and Kornberg, A. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 69-73; Arai, K., Low, R. L., and Kornberg, A. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 707-711). RNA primers covalently bound to the 5'-end of a DNA chain are heterogeneous with respect to both size and nucleotide composition. The chain length of the DNA-linked RNA primers is shorter than a decanucleotide, predominantly ranging from 1 to 9 residues. The primers start with adenylate followed mainly by a purine nucleotide (Pu) at the second position suggesting that pppA-Pu is a preferred initiation sequence. The inner sequences are more heterogeneous and no consensus or preferred sequence was found beyond the third position. The size distribution of the primer is influenced by the relative concentration of ribo- and deoxyribonucleoside triphosphates; the proportion of mononucleotide (riboadenylate) primer increases upon decreasing the relative ribonucleoside triphosphate concentration. Mapping of the transition sites from RNA to DNA on HaeIII endonuclease fragments suggest they are distributed randomly and occur frequently on the phiX174 genome. These results suggest that the selection of RNA priming sites is affected by primase at the preferred sequence 3'-T-pyrimidine nucleotide-5' on the template within the DNA domain generated by the dnaB protein. These properties of RNA priming have important implications for site selection by the primosome on the lagging strand at the replication fork of the E. coli chromosome.

Bacteriophage phi X 174↗
PubMed1983

Primer RNA for DNA synthesis on single-stranded DNA template in a cell free system from Drosophila melanogaster embryos.

A cytoplasmic extract of Drosophila melanogaster early embryos supported DNA synthesis which was dependent on an added single stranded DNA template, phi X174 viral DNA. The product DNA made during early reaction was about 100 to 600 nucleotides in length and complementary to the added template. After alkali treatment, 70 to 80 per cent of the product DNA chains exposed 5'-hydroxyl ends, suggesting covalent linkage of primer RNA at their 5'-ends. Post-labeling of 5'-ends of the product DNA with polynucleotide kinase and [gamma-32P]ATP revealed that oligoribonucleotides, mainly hexa- and heptanucleotides, were covalently linked to the 5'-ends of the majority of the DNA chains. The nucleotide sequence of the linked RNA was mainly 5'(p)ppApA(prN)4-5, where tri- (or di-) phosphate terminus was detected by the acceptor activity for the cap structure with guanylyltransferase and [alpha-32P]GTP. The structure of this primer RNA was comparable to that of the octaribonucleotide primer isolated from the nuclei of Drosophila early embryos.

Animals↗
PubMed1983

A rapid and specific enzymatic method for the quantification of phosphatidylcholine, disaturated phosphatidylcholine, and phosphatidylglycerol in amniotic fluid.

An enzymatic procedure for the quantification of phosphatidylcholine, disaturated phosphatidylcholine, and phosphatidylglycerol in amniotic fluid is described. By use of this method, choline and glycerol are released enzymatically from phosphatidylcholine and phosphatidylglycerol, respectively, in reactions catalyzed by phospholipase D. The hydrogen peroxide generated from choline (by the action of choline oxidase) and from glycerol (by the combined action of glycerokinase and glycerol-3-phosphate oxidase) is quantified spectrophotometrically after the addition of horseradish peroxidase, aminoantipyrine, and phenol. The phosphatidylcholine concentration in amniotic fluid was found to be approximately 10 to 30 nmol/ml between the twenty-third and thirty-sixth week of gestation and increased sevenfold to eightfold between the thirty-seventh week and term. The procedure can be modified for the quantification of disaturated phosphatidylcholine. The concentration of phosphatidylglycerol was approximately 2 nmol/ml between the twenty-third and thirty-sixth week and increased to 10 to 20 nmol/ml between the thirty-seventh and forty-first week of pregnancy. Since contamination of amniotic fluid with bile pigments does not interfere with either assay, the phosphatidylcholine and phosphatidylglycerol concentrations in amniotic fluid can be determined in samples that are contaminated with meconium.

Amniotic Fluid↗