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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 505 records · Page 28Linked to original sources
PubMed1981

[Application of the hydrogen washout technique to orthopedic research (author's transl)].

Since the first description by Aukland and co-authors in 1964, the hydrogen washout has been shown to be an accurate method in determining regional tissue blood flow. The presence of hydrogen molecules within the tissue is detected with a platinum electrode where a small amount of current is generated by oxidation of molecular hydrogen to hydrogen ions. Therefore, construction of the suitable electrode for the tissue to be measured is essential. The author applied the hydrogen washout technique to the blood flow measurement of bone, muscle, skin, digit and peripheral nerve, and found that the technique was valuable in basic and clinical studies in orthopedics. As a typical experimental study using the hydrogen washout technique, the study on the effect of adrenaline on bone blood flow was presented and the experimental method was explained in detail. Although the hydrogen washout technique has been developed to measure the blood flow, the technique has been found useful in detecting the pathways of microcirculation between different tissues. As an example, the study on nutritional pathways of the intervertebral disk was described. Since the hydrogen gas is harmless, it is possible to apply the technique to the clinical studies including the blood flow measurement of replanted digits, diagnosis of the compartment syndrome and the blood flow measurement of skin flaps. Furthermore, several problems in the hydrogen washout technique were discussed.

Animals↗
PubMed1980

Cross-linking of L5 protein to 5 S RNA in rat liver 60-S subunits by ultraviolet irradiation.

After rat liver 60-S ribosomal subunits were irradiated with ultraviolet light at 254 nm, they were treated with EDTA and then subjected to sucrose density-gradient centrifugation to isolate 5 S RNA-protein complex. When 5 S RNA-protein was analyzed by SDS-acrylamide gel electrophoresis which dissociated noncovalent 5 S RNA-protein, two protein bands were observed. The one showed a slower mobility than the protein band (L5) of 5 S RNA-protein from non-irradiated 60 S subunit and the other showed the same mobility as L5 protein. Since the former band was shown to be specific to ultraviolet-irradiation, it was considered as cross-linked 5 S RNA-protein. After the two protein bands were iodinated with 125 I, labeled protein was extracted and treated with RNAase. Thereafter, it was analyzed by two-dimensional acrylamide gel electrophoresis, followed by autoradiography. The results indicate that the protein component of cross-linked 5 S RNA-protein is L5 protein (ribosomal protein; these proteins are designated according to the proposed uniform nomenclature. The correlation between that and our nomenclature was reported by McConkey et al. (1979) Mol. Gen. Genet. 169, 1-6. They also confirm the results previously reported (Terao, K., Takahashi, Y. and O(gata, K. (1975) Biochim. Biophys. Acta 402, 230-237).

Animals↗
PubMed1980

Identification of neighbouring protein pairs in the rat liver 40-S ribosomal subunits cross-linked with dimethyl suberimidate.

(1) The 40-S ribosomal subunits of rat liver were treated with a bifunctional cross-linking reagent, dimethyl suberimidate. Cross-linked protein-protein dimers were separated by two-dimensional acrylamide gel electrophoresis. The stained cross-linked complexes within the gel were radioiodinated without the elution of proteins from the gel and were cloven into the original monomeric protein constituents by ammonolysis. The proteins in each dimer were finally identified by two-dimensional acrylamide gel electrophoresis of the cloven monomeric proteins, followed by radioautography of the stained gel. (2) The molecular weights of cross-linked complexes were determined by SDS-polyacrylamide gel electrophoresis and were compared with those of their constituent proteins. (3) The following dimers were proposed from these results: S3-S12 (S3 or S3a-S11), S4-S12 (S3b-S11, S5-S7 (S4-S6), S5-S22 (S4-S23 or S24), S6-S8 (S5-S7), S8-S16 (S7-S18), S17-S21 (S16--S19) and S22A-S22B (S23-S24), designated according to our numbering system [1]. The designations according to the proposed uniform nomenclature [2] are described in parentheses.

Acetates↗
PubMed1980

Stimulation by aminoacyl-tRNA of the GTPase and ATPase activities of rat liver 5S RNA protein particles in the presence of EF-2.

The GTP- and ATP-hydrolyzing activities of the rat liver 5S RNA-L5 (according to the proposed common nomenclature (1) protein complex designated as 5S RNP were stimulated by pig liver elongation factor 2 (EF-2) plus aminoacyl-tRNA, both of which were required for the stimulation. The stimulative effect of aminoacyl-tRNA on GTP hydrolysis by the complete system containing 5S RNP and EF-2 was dependent on the concentration of aminoacyl-tRNA. Aminoacyl-tRNA also stimulated ATP hydrolysis by the complete system but did not stimulate the ATP hydrolysis by 5S RNP alone or EF-2 alone. While deacylated tRNA stimulated the ATPase activity of the complete system, it had no effect on the GTPase activity. Preincubated tRNA lacking the 3'-terminal CCA moiety had little effect on the GTPase and ATPase activities of the complete system. Fusidic acid inhibited the GTPase and the ATPase activities of the complete system with and without aminoacyl-tRNA, although the extent of the inhibition was larger in the presence of aminoacyl-tRNA. These results suggest that 5S RNP may be a component of the GTPase center of rat liver 60S subunits.

Adenosine Triphosphatases↗
PubMed1980

Identification of neighboring protein pairs in rat liver 60S ribosomal subunits cross-linked with dimethyl suberimidate or dimethyl 3,3'-dithiobispropionimidate.

Protein-protein neighbors in rat liver 60S ribosomal subunits were investigated by using two bifunctional imidoesters; dimethyl suberimidate (DMS) and dimethyl 3,3'-dithiobispropionimidate (DTP). 1. Complexes cross-linked with DMS were separated by two-dimensional acrylamide/urea gel electrophoresis. Each complex in the gel was labeled with 125I (1) and was cleaved into the original monomeric protein constituents of ammonolysis. The products were analyzed by two-dimensional acrylamide/urea gel electrophoresis, followed by radioautography of the stained gel. Eight protein pairs are proposed according to our numbering system (2): L1-L3(L3-L5), L2-L21 (L4-L26), L5-L13 (L7/L7a-L15), L5-L34 L7/L7a-L36), L6-L34 (L8-L36), L6-L32 (L8-L35), L12-L32 (L13/L13a-L35), and L18-L27 (L18-L27/L27a). The designations according to the proposed uniform nomenclature (3) are given in parentheses. 2. Complexes cross-linked with DTP were analyzed by acrylamide/SDS diagonal gel electrophoresis (4), and the molecular weights of the complexes and their components were determined. The monomer components of cross-linked pairs were labeled with 125I in the gel, and identified by two-dimensional acrylamide/urea gel electrophoresis followed by radioautography. Six pairs are proposed; L1-L5 (L3-L7/L7a), L1-L6 (L3-L8). L5-L19 (L7-/L7a-L21/L23/L23a), L13-L15 (L15-L14), L13-L16 (L15-L19), and L23-L27 (L30-L27/L27a). 3. Two pairs which were formed by protein-protein interaction without the use of cross-linking reagents were identified as L2-L4 (L4-L6) and L4-L30 (L6-L29).

Animals↗
PubMed1980

Presence of a thiol protease in regenerating rat-liver nuclei. Partial purification and some properties.

1. Nuclei of regenerating rat liver washed with Triton X-100 were found to contain a new protease. Since the enzymatic activity for degrading ribosomal proteins was inhibited in vivo by administration of E-64, a thiol protease inhibitor, the enzyme may participate in the degradation of newly synthesized ribosomal proteins and histones in regenerating rat liver nuclei as reported previously by us [Biochem. Biophys. Res. Commun. 75, 525-531 (1077)]. The optimum pH was 5.5. 2. The enzyme was extracted from washed nuclei and partially purified by gel filtration through Sepharose 6B. Its molecular weight was about 40 000. A maximal activity of partially purified enzyme was observed in the presence of 1 mM EDTA and 2 mM dithiothreitol at pH 5.5 It was inhibited by thio reagents, E-64, leupeptin and hevy metal ions. The enzyme degraded ribosomal proteins endoproteolytically and degraded most proteins tested as substrates, although liver cell sap proteins and serum albumin were less degraded than ribosomal proteins and histones, alpha-N-Benzoylarginine-beta-naphthylamide and benzoylarginine amide were not hydrolyzed.

Animals↗
PubMed1979

Biosynthesis of ribosomal proteins by poly(A)-containing mRNAs from rat liver in a wheat germ cell-free system and sizes of mRNAs coding ribosomal proteins.

(1) Poly(A)-containing mRNAs from total polysomal RNA of regenerating rat liver were incubated with [3H]leucine in a wheat germ cell-free system. Ribosomal proteins were purified as described previously [1], and with two-dimensional gel electrophoresis. The proteins on the gel except for less basic protein had appreciable radioactivity, whereas the surrounding areas had very low radioactivity. Acetic acid-soluble proteins labeled in this system were subjected to three-dimensional gel electrophoresis [2]. Except for L1 and L2 proteins, each of the ribosomal proteins, including less basic ones, showed a major radioactive peak coinciding with the protein band on SDS gel. Thus, the wheat germ cell-free system completely translates almost all mRNAs for individual ribosomal proteins. Equimolar amounts of almost all ribosomal proteins were synthesized in the presence of the saturating concentration of mRNAs. (2) Free polysomes from regenerating rat liver were fractionated into three sizes. Each class of polysomes was incubated with [3H]leucine. Ribosomal proteins with molecular weights of 40 000 to 21 000 were mainly synthesized by Fraction B (5-14 monomeric ribosomes), L1 and L2 [2] with 60 000 and 54 000, by Fraction C (greater than 15 monomeric ribosomes) and B, and ribosomal proteins smaller than 20 000 by Fractions A (less than pentamer) and B. (3) mRNAs from rat liver total polysomes were fractionated into seven classes by size and each was translated in the wheat germ extract. Ribosomal proteins with molecular weights of 54 000 to 30 000 were mainly synthesized by mRNAs of 12 to 14.5 S, ribosomal proteins of 35 000 to 22 000 by those of 9.5 to 12 S, ribosomal proteins of 22 000 to 13 000 by those of 7 to 9.5 S, and smaller ribosomal proteins by those smaller than 7 S. These results indicate that individual ribosomal proteins are synthesized by monocistronic mRNAs, the lengths of which are proportional to the molecular weights of the corresponding ribosomal proteins.

Animals↗