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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 919 records · Page 51Linked to original sources
PubMed1979

Formaldehyde dehydrogenase from Pseudomonas putida. Purification and some properties.

Formaldehyde dehydrogenase was isolated and purified in an overall yield of 12% from cell-free extract of Pseudomonas putida C-83 by chromatographies on columns of DEAE-cellulose, DEAE-Sephadex A-50, and hydroxyapatite. The purified enzyme was homogeneous as judged by disc gel electrophoresis and was most active at pH 7.8 using formaldehyde as a substrate. The enzyme was also active toward acetaldehyde, propionaldehyde, glyoxal, and pyruvaldehyde, though the reaction rates were low. The enzyme was NAD+-linked but did not require the external addition of glutathione, in contrast with the usual formaldehyde dehydrogenase from liver mitochondria, baker's yeast, and some bacteria. The enzyme was markedly inhibited by Ni2+, Pd2+, Hg2+, p-chloromercuribenzoate, and phenylmethanesulfonyl fluoride. The molecular weight of the enzyme was estimated to be 150,000 by the gel filtration method, and analysis by SDS-polyacrylamide gel electrophoresis indicated that the enzyme was composed of two subunit monomers. Kinetic analysis gave Km values of 67 microM for formaldehyde and 56 microM for NAD+, and suggested that the reaction proceeds by a "Ping-pong" mechanism. The enzyme catalyzed the oxidation of formaldehyde accompanied by the stoichiometric reduction of NAD+, but no reverse reaction was observed.

Aldehyde Oxidoreductases↗
PubMed1978

Blood platelets as a possible source of creatine kinase in rat plasma and serum.

The creatine kinase (CK) activity in rat plasma was found to be correlated with that in serum or platelets. Rat serum contained higher activity not only of CK but also of lactate dehydrogenase than the corresponding plasma. The plasma CK activity decreased with increasing age of rats. Only the brain-type isoenzyme of CK was found in plasma, serum and platelets. Contamination of brain-type with muscle-type isoenzyme was detected in rather exceptional cases in which the activity was high among old rats. These results suggest the possible contribution of blood platelets to the CK activity of circulating plasma as well as to the activity in serum in rats.

Animals↗
PubMed1978

Creatine phosphate in rat blood platelets.

Creatine phosphate (CP) was found in rat platelets by an assay method devised to increase the specificity and sensitivity. In this method, radioactivity of [14C]ATP was measured after the reaction of CP with [14C]ADP in the presence of creatine kinase. The mean value of the CP content in rat platelets was 24.8 nmoles per 10(9) platelets. Since the molar ratio of CP and ATP was 1:2.6, it is probable that CP plays a role in the energy metabolism of rat platelets.

Adenosine Diphosphate↗
PubMed1978

The effect of mitomycin C on platelet aggregation and adenosine 3',5'-monophosphate metabolism.

The effect of Mitomycin C on aggregation, adenosine 3',5'-monophosphate (cyclic AMP) metabolism and reactions induced by thrombin was studied in rabbit platelets. Mitomycin C inhibited the platelet aggregation induced by adenosine diphosphate or thrombin. The level of radioactive cyclic AMP derived from 8-14C adenine or 8-14C adenosine increased after incubating intact platelets with Mitomycin C. Formation of radioactive adenosine triphosphate also increased though mitochondrial oxidation was not stimulated. Similar effect was observed also in rabbit liver. Mitomycin C failed to stimulate platelet adenyl cyclase but inhibited cyclic AMP phosphodiesterase in the absence of theophylline. In the platelets preincubated with Mitomycin C, thrombin-induced inhibition of adenyl cyclase, stimulation of membrane-bound cyclic AMP phosphodiesterase, and release of 250,000 dalton protein from platelet membranes were prevented. These results suggest that Mitomycin C will affect cellular membrane structure and function, and this extranuclear effect of Mitomycin C will lead to inhibition of aggregation in blood platelets.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Quantitation of berberine chloride in human urine by use of selected ion monitoring in the field desorption mode.

A method is described for the microdetermination of berberine chloride in human urine by a field desorption mass spectrometry selected ion monitoring system using a deuterium labelled analogue of berberine chloride as an internal standard. Prior to the quantitation of berberine in human urine, the fundamental problems related to field desorption selected ion monitoring, such as quality of emitters, amounts of sample loading, and the programming rate of the emitter current, were statistically investigated in detail. Berberine chloride can be determined in a concentration of 10 ng ml-1 in human urine by the method described. The analytical results were compared with those from gas chromatography mass spectrometry selected ion monitoring in the chemical ionization mode suggesting that the reliability of field desorption selected ion monitoring may be almost equivalent to that of gas chromatography chemical ionization selected ion monitoring.

Administration, Oral↗
PubMed1978

Calcium influx and spontaneous phasic contractions of portal veins after treatment with reserpine, 6-hydroxydopamine, and cocaine.

Reserpine treatment increased the amplitude of the spontaneous phasic contraction (SPC) of portal veins obtained from rabbit and guinea pig but did not alter that of rat. The amplitude of the SPC of portal veins from these animals was increased after 6-hydroxydopamine (6-OHDA) but was not changed after cocaine treatment. Reserpine- and 6-OHDA-induced changes in portal vein SPC amplitude were accompanied by an increase in 45Ca influx. These results indicate that the elevation in SPC amplitude is accompanied by an increase in calcium influx.

Animals↗
PubMed1978

Mechanisms by which smooth muscle sensitivity may be altered by calcium.

6-Hydroxydopamine (6-OHDA) increased the sensitivity of rat, rabbit and guinea pig portal veins to norepinephrine (NE), methoxamine (ME), barium (Ba++) and calcium (Ca++) but not to potassium (K+). Reserpine potentiated the responses of NE, ME and Ca++ but not Ba++ or K+ in rabbit and guinea pig veins and did not alter the sensitivity of rat veins to all agonists tested. Cocaine only potentiated the NE responses of the veins and decreased the sensitivity of rabbit and guinea pig veins to K+. 6-OHDA increased 48Ca-influx in all veins whereas reserpine increased 45Ca-influx only in rabbit and guinea pig veins. Cocaine failed to increase 45Ca-influx in all veins tested. NE, ME and K+ increased 45Ca-influx in the veins from the different animals. The agonist-induced 45Ca-influx was greater in most of the supersensitive veins than in the control veins. In veins that failed to develop supersensitivity, agonist-induced 45Ca-influx did not differ from that of the control veins. It is concluded that the development of super- and subsensitivity exhibits species variation and that the alteration in Ca++ influx would be consistent with the changes in sensitivity of the venous smooth muscle.

Animals↗
PubMed1978

Effect of cold storage on the sensitivity of and calcium influx into rat, rabbit and guinea pig portal veins.

After cold storage treatment (5-7 days at 2 degrees C) the sensitivity to norepinephrine (NE) was increased in rabbit portal vein, decreased in rat portal vein and not altered in guinea pig portal vein. Cold storage decreased the sensitivity to methoxamine (ME), Ba++ and Ca++ in rat and guinea pig veins but not in rabbit veins and failed to alter the sensitivity to K+ in all veins tested. Cold storage increased 45Ca-influx while it reduced the NE content and 3H-NE uptake of all portal veins examined. NE and ME-induced 45Ca-influx was greater in cold-stored veins that in fresh veins from rabbit and guinea pig. K+ decreased 45Ca-influx in all cold-stored veins. These results indicate that cold storage induces a prejunctional supersensitivity in rabbit portal vein but not in guinea pig and rat portal veins. However, cold storage increased 45Ca-influx in all three veins.

Animals↗
PubMed1978

Nephritogenic glycoprotein. VIII. Demonstration of the limited role of immune complex mechanism for the production of membranous glomerulonephritis.

Proliferative glomerulonephritis was induced in rats by a single injection in the hind footpads of the glycoprotein isolated from pronase digests of homologous renal cortex, in spite of the evidence that the glycoprotein no longer possessed the antigenic activity with respect to producing the nephrotoxic antibody. In rats given the glycoprotein (without trichloroacetic acid (TCA) treatment) prepared from pronase digests of homologous renal cortex, morphologic changes of proliferative glomerulonephritis were followed (3--4 months after injection) by those of typical membranous glomerulonephritis with an immunofluorescent 'granular' pattern, but in animals which received the glycoprotein (with TCA treatment), the morphologic changes of the kidney were those of proliferative glomerulonephritis with an immunofluorescent 'mesangial' pattern throughout the whole course. Morphologic changes of membranous glomerulonephritis induced in the group given the glycoprotein (without TCA treatment) can be explained by an immune-complex mechanism, superimposed on the basic pathogenesis (common to both groups) of proliferative glomerulonephritis with immunofluorescent 'mesangial' pattern.

Animals↗