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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 433 records · Page 24Linked to original sources
PubMed1982

Hemoglobin transition in early development stages of the tadpole, Rana catesbeiana.

Five hemoglobin components (a, I, II, III and IV) were isolated from the hemolysates of the tadpole, Rana catesbeiana. Component a was monomeric molecule and the other four were tetrameric molecules. Component I predominating in younger tadpoles was replaced by component II during tadpole development. Electrophoretic and chemical analyses on the constituent globin chains revealed that component a was very similar to the alpha-chains of components I and II, ad that components I and II differed from one another in their beta chains.

Animals↗
PubMed1982

The haemodynamics of Perthes' disease. An intraosseous venographic study combined with measurement of the intramedullary pressure.

Intraosseous venography and measurement of intramedullary pressure have been carried out in the metaphyses of 55 patients with unilateral Perthes' disease. Flow of the opaque medium into the diaphysis is the most important finding in intraosseous venography of the metaphysis. This was related to a rise of intramedullary pressure which indicates the presence of venous congestion within the metaphysis. While such congestion was seen both in the sclerotic stage and the segmentation stage, it was not related to the severity of Perthes' disease as judged by Catterall's [1] classification. Such venous congestion could be relevant to the pathogenesis of Perthes' disease, but there are probably different factors which determine the prognosis.

Child↗
PubMed1982

Changes in the density of circulating erythrocytes of the bullfrog tadpole, Rana catesbeiana, in relation to the transition of hemoglobin during metamorphosis.

1. The circulating erythrocytes of Rana catesbeiana tadpoles at varying metamorphic stages were studied by the phthalate-microcapillary technique of Danon & Marikovsky (1964 J. Lab. Clin. Med. 64, 668-674) and by the method of Murphy (1973 J. Lab. Clin. Med. 82, 334-341), which are used for the separation of erythrocytes according to the density. 2. The erythrocytes of tadpoles were different in the mean density from those of adult frogs. 3. At the metamorphic climax, aged erythrocytes having the tadpole hemoglobin coexisted with young erythrocytes having the frog hemoglobin in the circulating blood. 4. The frog hemoglobin was preferentially synthesized during metamorphosis. 5. All the results suggested that the transition of hemoglobin during metamorphosis was associated with the replacement of erythrocyte population.

Animals↗
PubMed1982

Studies on the reconstitution of macromomycin a d auromomycin from the chromophore and protein moieties.

The chromophores extracted from macromomycin (MCR) and auromomycin (AUR) with methanol had identical ultraviolet absorption spectra, antibacterial spectra and analytical profiles in high pressure liquid chromatography. The chromophore content of AUR was about 8 times higher than that of MCR. MCR reconstituted from the chromophore and protein fraction was identical with native MCR by Sephadex G-50 chromatography, ultraviolet absorption spectrum and antibacterial spectrum. The antibacterial activity of MCR and AUR was due to the chromophore; the protein moiety had no activity. However, the protein moiety enhanced the activity of the chromophore against Gram-positive bacteria, while it suppressed the activity against Gram-negative organisms. It also protected the chromophore from heat-inactivation.

Anti-Bacterial Agents↗
PubMed1982

[Enzymic determination of dipalmitoylphosphatidylcholine in human amnionic fluid--its application for the judgement of fetal lung maturity before birth (author's transl)].

Respiratory distress syndrome (RDS) is believed to be caused by a deficiency of pulmonary surfactant. The surfactant, secreted by fetal lung into amnionic fluid, has been analyzed by a variety of methods, but none of these methods have been found accurate enough to be widely used. Dipalmitoylphosphatidylcholine (DP-PC), the major surface-active component of the surfactant, occupies more than 50% of the surfactant phospholipids. In this study, DP-PC isolated from amnionic fluid, was determined enzymatically. DP-PC started to increase gradually in amnionic fluid from 22nd week of gestation, showed rather rapid increase after 35th week of pregnancy, and reached to a value of 6.97 +/- 0.56 mg/dl (Mean +/- SEM, n = 117) between 38 and 42nd week of gestation. This increase of DP-PC during gestation was found to be quite similar to that of L/S ratio reported previously. Eight out of 10 infants with RDS had less than 1.0 mg/dl of DP-PC in the amnionic fluid, whereas 137 infants without any sign of RDS had more than 1.0 mg/dl of DP-PC except 5 cases. These results demonstrated that if more than 1.0 mg/dl of DP-PC was found in amnionic fluid before birth, the fetus could be judged to have mature lung with 96% accuracy. In addition the enzymic determination of DP-PC requires less time, rather easy and reliable method to be done in most general clinical laboratories with less cost. Therefore we believe this method will be widely used in near future for the detection of RDS before birth.

Amniotic Fluid↗
PubMed1981

Characterization of nascent DNA fragments produced by excision of uracil residues in DNA.

Nascent short DNA chains could result from repair of incorporated uracil residues or be intermediates in discontinuous replication. We have characterized short DNA chains having apyrimidinic/apurinic-sites at 5' ends, the expected intermediates of repair, to distinguish them from RNA-linked replication intermediates. We have synthesized model substrates for the repair products; d(pRib[32P]poly(T)) and d(Rib[32P]poly(T)). Alkaline hydrolysis of both substrates has produced [5'-32P]poly(dT). Nascent short DNA was prepared from an Escherichia coli sof (dut) mutant, in this strain fragments from excision repair of uracil residues accumulate. The products of alkaline treatment are hardly digested by spleen exonuclease which selectively degrades 5'-hydroxyl-terminated DNA. These two results show that alkaline hydrolysis of the uracil repair fragments produces 5'-phosphoryl-terminated DNA, whereas it is known that 5'-hydroxyl-terminated DNA is generated from RNA-linked DNA molecules. The two types of nascent fragments thus can be distinguished by the 5'-terminal structure produced by an alkaline hydrolysis.

Animals↗
PubMed1981

Diacylglycerol metabolism and arachidonic acid release in human fetal membranes and decidua vera.

Diacylglycerol lipase activity has been demonstrated in human fetal membranes and decidua vera tissues. The specific activity of the enzyme is highest in the microsomal fraction of decidua vera tissue. The acylester bond at the sn-1 position of 1,2-diacyl-sn-glycerol is hydrolyzed followed by release of the fatty acid at the sn-2 position. The diacylglycerol lipase activity present in the microsomal fraction of decidua vera tissue hydrolyzes preferentially a diacylglycerol containing an arachidonoyl group in the sn-2 position. Monoacylglycerol lipase activity was also demonstrated in these tissues. The specific activity of monoacylglycerol lipase was significantly greater than that of diacylglycerol lipase and catalyzed preferentially the hydrolysis of monoacylglycerols containing an arachidonyl group in the sn-2 position. Based on the subcellular distribution and the differential effects of various inhibitors, we suggest that the monoacylglycerol lipase and diacylglycerol lipase in decidua vera tissue are 2 distinct enzymes. Diacylglycerol kinase specific activity was examined also and was found to be 4-5 times greater in amnion than in either chorion laeve or decidua vera. The importance of diacylglycerol metabolism in the mechanism of arachidonic acid release and prostaglandin biosynthesis is discussed.

Arachidonic Acid↗
PubMed1981

Initiation of human parturition. XII. Biosynthesis and metabolism of prostaglandins in human fetal membranes and uterine decidua.

Prostaglandin synthetase activity was assayed in homogenates prepared from human fetal membranes and uterine decidua tissues with [14C] arachidonic acid used as substrate. In amnion, chorion laeve, and decidua vera tissues obtained after the spontaneous onset of labor and vaginal delivery the mean specific activities of prostaglandin synthetase were respectively 1.47, 0.53, and 0.39 nmoles x hr-1 x gm-1 tissue; in these same tissues obtained at elective cesarean section before the onset of labor the mean specific activities of prostaglandin synthetase were respectively 0.61, 0.33, and 0.28. The specific activity of prostaglandin synthetase of amnion (but not chorion laeve or decidua vera) was significantly greater in samples obtained after labor than in those obtained before labor (p less than 0.02). Prostaglandin synthesis in amnion, chorion laeve, and decidua vera was inhibited by acetylsalicylic acid and by indomethacin. Prostaglandin E2 was formed in amnion and chorion laeve, whereas prostaglandin E2 and prostaglandin F2 alpha were formed in decidua vera. The activity of NAD+ -dependent 15-hydroxyprostaglandin dehydrogenase was also assayed and the specific activities of this enzyme in chorion laeve and decidua vera tissues obtained before and after labor were high, whereas 15-hydroxyprostaglandin dehydrogenase activity in amnion was low.

Amnion↗
PubMed1981

Sodium and rubidium uptake in cells transformed by Rous sarcoma virus.

Rates of uptake and intracellular concentrations of monovalent cations were measured in virus-transformed and nontransformed chick embryo (CE) cells. Uptake of 22Na+ into cells transformed by the BH strain of Rous sarcoma virus (RSV-BH) (CE-BH) was about double the rate of uptake into CE cells, or cells transformed by the Schmidt-Ruppin strain (RSV-SR): CE-SR. Likewise, the rate of efflux of 22Na+ was greater in CE-BH cells than in CE or CE-SR cells. The greater permeability of CE-BH cells to Na+ was apparent in higher intracellular Na+ concentrations. Experiments with cells exhibiting temperature-dependent transformation showed that new RNA and protein synthesis was a requirement for the acquisition of increased Na+ permeability, suggesting that the change is an indirect effect of the virus-coded transformation-inducing protein. Rates of 86Rb+ uptake, used as a measure of K+ influx, were indistinguishable in CE, CE-BH, and CE-SR cells. Also, equilibrium intracellular levels of 86Rb+ were similar in transformed and nontransformed cells, as were observed concentrations of K+. Also, no differences in ATPase activity, as indicated by ouabain binding or temperature sensitivity, were observed. We conclude that monovalent cations play no direct role in RSV-induced transformation, although the higher levels of Na+ in CE-BH cells may be responsible for other distinguishing biochemical features of these cells.

Animals↗
PubMed1981

Initiation sites for discontinuous DNA synthesis of bacteriophage T7.

We have previously shown that the discontinuous replication of bacteriophage T7 DNA is primed by tetraribonucleotides (major component) or pentaribonucleotides. Both tetramers and pentamers start with pppA-C and are rich in A and C at the third and fourth nucleotides. In this study, the sites of transition from primer RNA to DNA in vivo have been located on a 340-nucleotide segment of the H strand of the T7 genome by 32P-labeling in vitro of the 5'-hydroxyl ends of DNA resulting from alkaline hydrolysis of RNA-linked T7 DNA fragments. Five strong transition sites were detected with a common sequence 5'-G-A-C-N1-N2-N3-N4-3', in which N1 was either C or A, N2 ws A, C, or G, and either N3 or N4 was the nucleotide for the switchover to DNA synthesis. We conclude that the complementary sequence 3'-C-T-G-G/T-N'2-(N'3)-5' in the template strand is the most frequently used signal for synthesis of primer RNA. Whereas primer-RNA synthesis starts at a precisely defined nucleotide, the transition to DNA synthesis varies within two nucleotides. Because the observed signal sequence would be present on a statistical basis once per 128 nucleotides, only about 10% of the existing signals are used for primer synthesis in each round of replication so that nascent fragments 1000-2000 long result. This provides an unexpected flexibility for RNA priming of DNA synthesis.

Base Sequence↗