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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 541 records · Page 30Linked to original sources
PubMed1978

The role of ATP in the transport of rapidly-labeled RNA from isolated nuclei of rat liver in vitro.

To understand the mechanism of the action of ATP on the in vitro transport of the rapidly-labeled RNA from isolated nuclei, the fate of ATP during the incubation as well as the effect of ATP, its analogues and other ribonucleoside triphosphates on the transport was examined and the following results were obtained. (1) More than 97% of added ATP remained acid soluble. No polyadenylation of the rapidly-labeled RNA in the released fraction by added ATP occurred although new polyadenylate segments smaller than 10 S were synthesized. (2) The addition of an ATP-generating system to the reaction mixture restored the initial rate of the release of the rapidly-labeled RNA from isolated nuclei. (3) Among the ribonucleoside triphosphates tested, ATP was most effective in stimulating the release. GTP was about 2/3 as effective as ATP. UTP showed some effect, but CTP showed no effect. EDTA was also non-effective. (4) When no ATP-generating system was added to the reaction mixture, AMP failed to mimic the effect of ATP. However, the combination of AMP and pyrophosphate could take the place of ATP. (5) Both AMP-CPP and AMP-PCP, the ATP analogues, showed the equal degree of their effect on the release, regardless of the position of the methylene bond. From these results, the principal role of ATP in the in vitro transport systems seemed to be its interaction with isolated nuclei to dissociate a structure which retains the rapidly-labeled RNA in the nucleus.

Adenosine Triphosphate↗
PubMed1978

The different molecular weight forms of bovine liver rhodanese.

Sedimentation equilibrium studies show that there are two forms of bovine liver rhodanese in crystalline enzyme preparations of full specific activity. One form dissociates to a species with a limiting molecular weight close to 19,000. The second form is nondissociable under the same experimental conditions. It exhibits a molecular weight of approximately 33,000. These conclusions are augmented by data from polyacrylamide gel electrophoresis and molecular exclusion chromatography. They serve to explain apparent inconsistencies in previous reports on this enzyme.

Animals↗
PubMed1978

3-Hexulosephosphate synthase from Methylomonas aminofaciens 77a. Purification, properties and kinetics.

3-Hexulosephosphate synthase (D-arabino-3-hexulose 6-phosphate formaldehyde lyase) was purified from an obligate methylotroph, Methylomonas aminofaciens, to homogeneity as judged by polyacrylamide gel electrophoresis and analytical ultracentrifugation. The molecular weight was determined to be 45 000-47 000 by sedimentation velocity and gel filtration. The enzyme appears to be composed of two identical subunits (Mr = 23 000). A bivalent cation is required for the activation and stabilization of the enzyme. The enzyme is specific for formaldehyde and D-ribulose 5-phosphate. The optimum pH is 8.0 (isoelectric point, pH 5.1) and the optimum temperature is 45 degrees C. Initial velocity studies are consistent with a sequential mechanism. The Michaelis constants are 0.29 mM for formaldehyde and 0.059 mM for D-ribulose 5-phosphate.

Aldehyde-Lyases↗
PubMed1978

Hand orthosis for various finger impairments--the K U finger splint.

The K U (Kumamoto University) finger splint has been manufactured for the purpose of developing an effective hand orthosis for various finger impairments using simple parts and materials. By combining the W type orthosis for which piano wire is mostly used, and the S type for which fishing line is mainly used, it has been used to good effect on patients with several kinds of finger impairments. The fabrication and adjustment of the orthosis is simple and if the material is in kit form, a doctor or an occupational therapist can at once construct one and give it to a patient. For this reason, the patient will not lose the chance of timely treatment.

Fingers↗
PubMed1978

The different effects of N-ethylmaleimide and iodoacetamide on the activity of rat liver 60S subunits for peptide bond elongation.

The activity of 60S subunits of rat liver ribosomes in poly(U)-dependent polyphenylalanine synthesis was inhibited by incubation with N-ethylmaleimide. However, when 60S subunits were incubated with iodoacetamide, their activity decreased only slightly. Furthermore, iodoacetamide-pretreated 60S subunits became insensitive to N-ethylmaleimide. Similar results were obtained for the activity of EF-2-dependent GTPase of 60S subunits. As a whole, the labeling patterns of ribosomal proteins on two-dimensional gel electrophoresis were similar for 60S subunits labeled with both 14C-labeled sulfhydryl reagents, although the extent of labeling of some proteins was somewhat different. These results indicate that the SH groups in the 60S subunits are not directly involved in the activities of the subunits described above.

Animals↗
PubMed1978

Bacterial oxidation of polyethylene glycol.

The metabolism of polyethylene glycol (PEG) was investigated with a synergistic, mixed culture of Flavobacterium and Pseudomonas species, which are individually unable to utilize PEGs. The PEG dehydrogenase linked with 2,6-dichlorophenolindophenol was found in the particulate fraction of sonic extracts and catalyzed the formation of a 2,4-dinitrophenylhydrazine-positive compound, possibly an an aldehyde. The enzyme has a wide substrate specificity towards PEGs: from diethylene glycol to PEG 20,000 Km values for tetraethylene glycol (TEG), PEG 400, and PEG 6,000 were 11, 1.7, and 15 mM, respectively. The metabolic products formed from TEG by intact cells were isolated and identified by combined gas chromatography-mass spectrometry as triethylene glycol and TEG-monocarboxylic acid plus small amounts of TEG-dicarboxylic acid, diethylene glycol, and ethylene glycol. From these enzymatic and analytical data, the following metabolic pathway was proposed for PEG: HO(CH2CH2O)nCH2CH2OH leads to HO(CH2CH2O)nCH2CHO leads to HO(CH2CH2O)nCH2COOH leads to HO(CH2CH2O)n-1CH2CH2OH.

Chemical Phenomena↗
PubMed1978

Vitamin B6 biosynthesis and nucleoside effect in the resting cell system of Flavobacterium sp. 238-7.

As one of the attempts to find clues on precursors or intermediates of the vitamin B6 biosynthetic pathway, the resting cell system of Flavobacterium sp. 238-7, a bacterium producing a high amount of the vitamin, was employed. Among various compounds tested as an additive to the reaction mixture, L-glutamate and nucleoside derivatives increased the formation of vitamin B6, respectively. The possible mechanism of the participation of these compounds in vitamin B6 biosynthesis is discussed. The identification of vitamin B6 formed in the reaction mixture was done using column chromatography.

Amino Acids↗
PubMed1978

Subchondral route for nutrition to articular cartilage in the rabbit. Measurement of diffusion with hydrogen gas in vivo.

The route of nutrients going to articular cartilage was studied by determining the diffusion of hydrogen molecules from the subchondral circulation to the articular cartilage in rabbits. In all immature animals there was diffusion of hydrogen from subchondral bone into articular cartilage, while in the older immature animals the results were variable. None of the mature animals showed any diffusion of hydrogen into articular cartilage. The rate of diffusion of hydrogen was significantly lower in the articular cartilage than in the subchondral bone in the immature animals while the concentrations of hydrogen in the articular cartilage were only fractions of those in the subchondral bone at the same instant. Histologically, the deep layers of immature cartilage are penetrated extensively by vascular buds from the ossified portion of the epiphysis, while in adults the articular cartilage is separated from subchondral vascular spaces by an end-plate of bone. Blood vessels penetrating into the basilar layer of articular cartilage in immature animals appear to play an important role in the nutrition of articular cartilage coming from the subchondral region.

Animals↗