Biomedical subjects

I Hamamoto

Publications and source records attributed to I Hamamoto.

61 records · Page 4Linked to original sources

PubMed1988

Adrenoferredoxin-binding peptide of NADPH-adrenoferredoxin reductase.

The amino-acid sequence at the adrenoferredoxin-binding site of NADPH-adrenoferredoxin reductase ferredoxin:NADP+ oxidoreductase, EC 1.18.1.2) from bovine adrenocortical mitochondria was investigated chemically. NADPH-adrenoferredoxin reductase has an essential lysine residue at the adrenoferredoxin-binding site. A polypeptide at the adrenoferredoxin-binding site was isolated by high-pressure liquid chromatography from NADPH-adrenoferredoxin reductase modified with pyridoxal 5'-phosphate and cleaved with cyanogen bromide. The amino-acid sequence of the adrenoferredoxin-binding peptide was identified. The peptide accounted for 95% of the sugar content of the NADPH-adrenoferredoxin reductase.

Adrenal Cortex↗

PubMed1986

Quantitative analysis of the mitochondrial cytochrome P-450-linked monooxygenase system: NADPH-hepatoredoxin reductase, hepatoredoxin, and cytochrome P-450s27 in livers of patients with cerebrotendinous xanthomatosis.

We studied the mitochondrial cytochrome P-450-linked monooxygenase system in livers of two patients with cerebrotendinous xanthomatosis (CTX). The three components of this system, which catalyzes steroid 27-hydroxylation, NADPH-hepatoredoxin reductase, hepatoredoxin, and cytochrome P-450s27, were stained on a nitrocellulose sheet with antibodies against NADPH-adrenodoxin reductase, adrenodoxin, and cytochrome P-450scc, respectively, from bovine adrenocortical mitochondria. The concentrations of hepatoredoxin in the patients were not significantly different from a control, but the level of NADPH-hepatoredoxin reductase was three times that of the control. Cytochrome P-450s27 was not detected in the patients, but it was present (22.8 pmol/mg of protein) in the control liver. This implies that a defect of mitochondrial cytochrome P-450s27 prevents steroid 27-hydroxylation of hepatic mitochondria in patients with CTX.

Adrenal Cortex↗

PubMed1986

Zonal distribution of cytochromes P-450 and related enzymes of bovine adrenal cortex--quantitative assay of concentrations and total contents.

The zona glomerulosa, zona fasciculata, zona reticularis, and medulla were separated from bovine adrenal glands and cytochromes P-450 and related enzymes in each zone were investigated immunochemically by Western blotting using antisera from chickens or rabbits against cytochromes P-450scc, P-450(11)beta, P-450s21, and b5, NADH-cytochrome b5 reductase, NADPH-cytochrome P-450 reductase, NADPH-adrenodoxin reductase, and adrenodoxin. Concentrations of cytochrome P-450(11)beta, NADPH-cytochrome P-450 reductase, and cytochrome b5 per milligram of protein of homogenate were higher in the zona glomerulosa than in the other zones; the levels of the other components were higher in the zona fasciculata. The total enzyme content of all components was the highest in the zona fasciculata. The amount of adrenodoxin was about 10 times that of NADPH-adrenodoxin reductase in each zone.

Adrenal Cortex↗

PubMed1985

Purification and kinetic properties of 3 beta-hydroxysteroid dehydrogenase from bovine adrenocortical microsomes.

3 beta-Hydroxysteroid dehydrogenase was purified from bovine adrenocortical microsomes and its properties were studied. The purified dehydrogenase gave a single homogeneous protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and showed no steroid delta 5-delta-4 isomerase activity. The molecular weight of the dehydrogenase was estimated to be 41,000 for the monomer and the isoelectric point was determined to be at pH 6.3. The Km values of the dehydrogenase were 6.2 microM for NAD+, 4.9 mM for NADP+, 2.0 microM for pregnenolone, and 5.3 microM for 17 alpha-hydroxypregnenolone. The mechanism of inhibition by trilostane of the dehydrogenase was also examined kinetically. The inhibition was found to be competitive, with Ki values of 0.14 microM for 17 alpha-hydroxypregnenolone and 0.38 microM for pregnenolone.

17-alpha-Hydroxypregnenolone↗

PubMed1984

Modification of a lysine residue of adrenodoxin reductase, essential for complex formation with adrenodoxin.

The NADPH-cytochrome c reductase activity of NADPH-adrenodoxin reductase from NADPH to cytochrome c via adrenodoxin was inhibited by pyridoxal 5'-phosphate and other reagents that modified the lysine residues. However, the NADPH-ferricyanide reductase activity was not affected. Loss of the cytochrome c reductase activity could be prevented by adrenodoxin, but not by NADP+. One lysine residue of the adrenodoxin reductase could be protected from the modification with pyridoxal 5'-phosphate by complex formation with adrenodoxin. Loss of the NADPH-cytochrome c reductase activity was not due to the conformational change of the modified adrenodoxin reductase, judging from circular dichroism spectrometric studies.

Adrenal Cortex↗

PubMedDate not supplied

Basic study on hepatic resection under partial perfusion cooling.

To improve liver quality after reperfusion following partial hepatectomy under total or partial cooling of the liver (HPC), a new perfusion solution containing 100 mM L-histidine (KM solution) was developed. The livers of Lewis rats were removed and perfused for 2 hours at 20 degrees C with lactated Ringer's (LR) solution (group A) or the KM solution (group B). They were reperfused with rat blood at 37 degrees C at a perfusion pressure of 5 cmH2O while monitoring the portal and peripheral tissue blood flows. At the end of reperfusion, bile production, lactate dehydrogenase (LDH) secretion, and tissue adenosine triphosphate (ATP) was measured. Recovery of portal and peripheral tissue blood flows of the group B livers after reperfusion were significantly better than those of group A. Viability of the group B livers, assessed by bile production, tissue ATP value, and LDH release, was preserved better than that of group A livers. In situ total liver perfusion with LR (group C) and KM (group D) solutions for 1 hour at 20 degrees C followed by partial hepatectomy of the left lateral lobe was performed. The 1-week survivals of the group C and D rats were 25% and 100%, respectively (p < 0.05). It was concluded that KM solution is suitable for HPC.

Animals↗

PubMedDate not supplied

Hyperbaric nitrogen and pentobarbital on synaptosomal membrane lipids and free fatty acids.

Nitrogen at high pressures and anesthetics increase lipid monolayer surface pressure and in turn modulates monolayer associated lipolytic enzyme activity that could alter membrane lipids. We tested the hypothesis that nitrogen at pressures of 5 and 10 megapascals (MPa) and pentobarbital induce alterations in synaptosomal membrane phospholipid and free fatty acid (FFA). Rat cortical synaptosomes in Krebs-Henseleit buffer were placed in steel chambers and incubated for four hours at 37 degrees C: at 5 or 10 MPa of O2/balance N2; at one 0.1 MPa on room air, and with 10 mg pentobarbital. Free fatty acids (FFA) were quantified by thin-layer and gas chromatography, and neutral and acidic lipids by high-pressure thin layer chromatography and protein by Biorad colorimetric assay. Statistical analyses were by ANOVA and posthoc analysis by Neuman-Keuls and Kruskal-Wallis tests at p < 0.05. Sphyngomyelin, phosphatidylcholine, phosphatidylethanolamine, cerebroside and cholesterol were unchanged by 5 and 10 MPa nitrogen and pentobarbital. Free fatty acids (16:00, 18:00, 18:01, 20:00, 22:0, 22:01 and 24:01) at 10 MPa were reduced compared to 5 MPa (p < 0.05) but unaffected by pentobarbital. The decrease in synaptosomal membrane FFA at 10 MPa suggests attenuated hydrolysis of membrane phospholipids without detectable alterations in membrane phospholipid composition.

Anesthesia↗