Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 397 records · Page 22Linked to original sources

PubMed1992

NADPH-cytochrome c (P-450) reductase has the activity of NADPH-linked aquacobalamin reductase in rat liver microsomes.

To elucidate the mammalian system for synthesis of cobalamin coenzymes, microsomal NADPH-linked aquacobalamin reductase was purified and characterized. The enzyme was purified about 534-fold over rat liver microsomal fraction in a yield of about 32%. The purified enzyme was homogeneous in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and had a monomeric molecular weight of 79,000. The purified aquacobalamin reductase showed a high specific activity (about 55 mumol/min per mg protein) of NADPH-cytochrome c (P-450) reductase. About 33% of the NADPH-cytochrome c reductase activity found in the microsomal fraction was recovered in the final purified preparation. The activity ratio of NADPH-cytochrome c reductase/NADPH-linked aquacobalamin reductase was about 5.0 through the purification steps, indicating that the rat liver microsomal NADPH-linked aquacobalamin reductase is the NADPH-cytochrome c reductase.

Animals↗

PubMed1992

Epoxyeicosatrienoic acid stimulates ADP-ribosylation of a 52 kDa protein in rat liver cytosol.

In rat liver cytosol, rapid ADP-ribosylation of a 52 kDa protein by endogenous ADP-ribosyltransferase(s) was observed. This ADP-ribosylation was stimulated dose-dependently by 14,15-epoxyeicosatrienoic acid (14,15-EET), one of the metabolites of arachidonic acid by NADPH-dependent cytochrome P-450 mono-oxygenase. This stimulatory effect required the presence of GTP or its non-hydrolysable analogues, guanosine 5'-[beta gamma-imido]triphosphate or guanosine 5'-[gamma-thio]triphosphate. Of four regioisomeric EETs, 14,15-EET was the most potent. No stimulatory effect was observed with addition of 14,15-dihydroxyeicosatrienoic acid, a stable metabolite of 14,15-EET. The 52 kDa protein was not ADP-ribosylated by cholera toxin A subunit and pertussis toxin, and was not recognized by anti-Gs alpha and anti-Gi alpha antibodies. However, the 52 kDa protein could be photoaffinity-labelled with 8-azidoguanosine 5'-[alpha-32P]triphosphate. These results suggest that the 52 kDa protein is neither Gs nor Gi, though it may have a GTP-binding site. These results contribute to the understanding of the role of mono-oxygenase metabolites of arachidonic acid in intracellular signal transduction.

8,11,14-Eicosatrienoic Acid↗

PubMed1992

Radiolunate and radioscapholunate arthrodesis.

Eleven patients underwent radiocarpal arthrodesis for a wrist disease other than rheumatoid arthritis. Operations included seven radiolunate fusions and four radioscapholunate fusions. The indication for surgery was posttraumatic changes secondary to radius fracture (five), Kienböck's disease (three), localized arthritis secondary to sepsis (two) and acute comminuted fracture of the distal radius (one). All patients had arthritis or post-traumatic changes limited to the articulation between the radius and carpus. Follow-up ranged from 24 months to 7 years, with an average of 41 months. Postoperatively, average range of motion of the wrist was 30.9 degrees of extension, 22.7 degrees of flexion, 10 degrees of radial deviation, and 19.3 degrees of ulnar deviation, and grip strength averaged 81.8% of that for the uninvolved hand. Pain relief was achieved in all patients, and they were able to return to their previous occupation. Bony union was achieved in all cases. Degenerative changes in the midcarpal joint were not seen.

Adult↗

PubMed1992

The role of 5-hydroperoxyeicosatetraenoic acid in neutrophil activation.

5-Hydroperoxyeicosatetraenoic acid (5HPETE) has been recently reported to play an important role in regulating and modulating neutrophil function. In order to clarify the mechanism of neutrophil activation by 5HPETE, we have measured the cytosolic free calcium, which is thought to be necessary for neutrophil activation using fura-2-loaded human neutrophils. Low concentration of 5HPETE, which is thought to be produced during cell activation, had minimal effect on cytosolic free calcium by itself but dose-dependently augmented FMLP-stimulated increase in cytosolic free calcium in the presence or absence of extracellular calcium without converting to LTB4. 5HPETE had no effect on 3H-FMLP binding to human neutrophils. The present data suggested that 5HPETE would augment FMLP-stimulated increase in cytosolic free calcium by enhancing the influx of extracellular calcium and/or the release of calcium from intracellular pool, which resulted in augmentation of neutrophil activation by primary agonist such as FMLP.

Binding Sites↗

PubMed1992

Balloon catheter with check valves for experimental relief of acute aortic regurgitation.

To evaluate the ability of a newly designed balloon catheter with check valves to temporarily relieve hemodynamic deterioration in acute aortic regurgitation, we produced an experimental model of acute aortic regurgitation in closed-chest dogs using endomyocardial biopsy forceps. Aortic regurgitation was produced until an increase in aortic pulse pressure of over 50% was achieved. Left ventricular end-diastolic pressure rapidly increased after the production of aortic regurgitation. Immediately after the catheter began functioning, pulse pressure decreased from 133 +/- 1 to 78 +/- 5 mm Hg (mean +/- SEM) and left ventricular end-diastolic pressure also decreased from 26 +/- 1 to 13 +/- 1 mm Hg. These effects lasted as long as the catheter functioned. Although a mild (21 +/- 8 mm Hg) pressure gradient between the left ventricular peak systolic pressure and the aortic peak systolic pressure was observed when this catheter was used, forward stroke volume was no less than in the group in which the catheter had not been used. These findings suggest that the balloon catheter with check valves may effectively reduce aortic regurgitation.

Animals↗

PubMed1992

Eicosapentaenoic acid inhibits cholesteryl ester accumulation in rat peritoneal macrophages by decreasing the number of specific binding sites of acetyl LDL.

We found that rat peritoneal macrophages bind acetyl low density lipoprotein (AcLDL) by a saturable and specific manner and accumulate a substantial amount of cholesteryl ester (CE) when incubated with AcLDL. In macrophages enriched with eicosapentaenoic acid (EPA) by the ingestion of highly purified eicosapentaenoic acid-ethyl ester (EPA-E), the accumulation of CE was significantly decreased in a dose-dependent manner. In addition, the contents of EPA and docosapentaenoic acid (DPA) in macrophage phospholipids were dose dependently and significantly increased by EPA-E feeding. In contrast, the contents of arachidonic acid (AA) and docosahexaenoic acid (DHA) were unchanged. Furthermore EPA-E ingestion significantly decreased the Bmax of the AcLDL receptor without affecting the Kd in rat peritoneal macrophages. In addition, specific proteolytic degradation of AcLDL was also dose dependently inhibited by EPA-E feeding, indicating that the number of AcLDL receptor was significantly decreased after EPA-E ingestion. These findings indicate that EPA-E feeding inhibited CE accumulation mainly by decreasing the AcLDL receptors in macrophages. We speculate that EPA inhibits foam cell formation and this inhibitory effect may partly account for its anti-atherogenic action.

Administration, Oral↗

PubMed1992

Effect of ingestion of eicosapentaenoic acid ethyl ester on carrageenan-induced colitis in guinea pigs.

The effect of highly purified eicosapentaenoic acid ethyl ester (EPA-E) on colitis was investigated using a guinea pig model. The technique for preparing a degraded carrageenan with a molecular weight of about 30,000 from commercial iota-carrageenan was first refined. When this degraded carrageenan was fed to guinea pigs, localized ulcerations occurred in the cecum with infiltration of numerous mononuclear phagocytes. Oral administration of 300 mg.kg-1.day-1 of EPA-E for 3 weeks significantly prevented the development of colitis. The amounts of prostaglandin E2, thromboxane B2, and leukotriene B4 released from the cecal mucosa were also measured. The release of prostaglandin E2 and thromboxane B2 was significantly decreased in the animals fed EPA-E compared with those given olive oil or a vehicle alone. In addition, there was a positive correlation between the amounts of these eicosanoids and the degree of ulcer formation. However, there was no difference in the amount of leukotriene B4 among various experimental groups of animals. Furthermore, EPA-E feeding induced a significant decrease in the level of arachidonic acid and a significant increase in that of EPA in peritoneal macrophages. These results suggest that EPA has a prophylactic effect on the development of carrageenan-induced colitis, which may be ascribed in part to reduced eicosanoid production.

Animals↗

PubMed1992

Aspergillotic aneurysm formation of cerebral artery following neurosurgical operation.

A rare case of intracranial aspergillotic aneurysm following neurosurgical operation for facial spasm is presented. Severe meningitis had persisted several days prior to the subarachnoid hemorrhage which occurred on 70th postoperative day. Angiography demonstrated a fusiform aneurysm at the peduncular segment of the superior cerebellar artery on the other side of operation. As the repeated cultures of CSF were negative, the pathogenetic factor causing aneurysm formation could not be identified before second operation of aneurysmal resection. Pathological study of the specimen revealed the arterial wall being deeply invaded by aspergillotic hyphae.

Adult↗

PubMed1992

Long-standing extended dynamic splintage and release of an abnormal restraining structure in camptodactyly.

62 patients with camptodactyly of the little finger have been reviewed, and only five cases failed to respond to conservative treatment. These cases are reported. One patient could straighten the deformed PIP joint with snapping, and the other two were resistant to conservative treatment and were found to have a restraining structure requiring release. These findings are in keeping with an imbalance between flexion and extension forces due to long-standing malposition of the extensor lateral bands. Operative treatment should be reversed for cases of failed conservative treatment, which should be started as early as possible.

Adult↗

PubMed1992

Role of elastase as a virulence factor in experimental Pseudomonas aeruginosa infection in mice.

The role of elastase and alkaline protease in the pathogenesis of fatal infections caused by Pseudomonas aeruginosa was determined in mice treated with calcium chloride. Mortality increased significantly when solutions containing elastase were injected together with non-lethal inocula of strain PA 103, which does not produce proteolytic enzyme. In contrast, solutions containing alkaline protease did not increase mortality. In mice injected intramuscularly with strain PA 103 and calcium chloride, the organisms grew rapidly in the injected muscle but not in the liver. However, when elastase was injected together with strain PA 103 and calcium chloride, viable bacteria were also found in the liver. Moreover, the survival rate of mice challenged with elastase-producing strain 5 and calcium chloride was enhanced, and colonization of the liver prevented, by immunization with elastase toxoid. These results suggest that elastase contributes to the invasiveness of the organism.

Animals↗

PubMed1992

Reperfusion injury in bone: effects of CV-3611, a free radical scavenger, on ischemic revascularized bone grafts in rats.

Oxygen-derived free radicals have been shown to play an important role in reperfusion injury. The protective effect of CV-3611, a new free radical scavenger, on reperfusion injury in an ischemic revascularized hind limb model in rats was examined. Warm ischemia (25 degrees C) was produced by vascular pedicle clamping and sustained for 0, 3, and 6 hr. Histologic and fluorochrome bone-labeling analyses demonstrated improved overall viability of osteocytes, osteoblasts, and marrow cells in the CV-3611-treated group compared to controls. The CV-3611-treated group had statistically significant improvement in the ratio of lacunae, maintained osteogenetic ability, and preserved normal growth plate architecture after 6 hr of ischemia. The control group showed local central areas of disorganization by 3 hr and complete destruction of the growth plate with early growth arrest after 6 hr of ischemia. These results indicate that administration of CV-3611 prior to reperfusion can prevent reperfusion damage in bone tissue and maintain osteogenetic ability. This technique may have clinical application for reducing the complications of prolonged ischemia to bone tissue.

Animals↗

PubMed1992

Cytochrome b5/cytochrome b5 reductase complex in rat liver microsomes has NADH-linked aquacobalamin reductase activity.

To study the mammalian system for synthesis of cobalamin coenzymes, rat liver microsomal NADH-linked aquacobalamin reductase was characterized. Microsomal NADH-linked aquacobalamin reductase, which was solubilized with 10 g/L sodium deoxycholate, showed identical elution behavior to NADH-cytochrome c reductase (cytochrome b5/cytochrome b5 reductase complex) on DEAE-Toyopearl 650 column chromatography. By mixing the purified cytochrome b5 with cytochrome b5 reductase, cob(II)alamin was immediately formed from aquacobalamin and NADH. These results provide evidence that the NADH-linked aquacobalamin reductase activity is derived from the cytochrome b5/cytochrome b5 reductase complex in rat liver microsomes. Some properties of the cytochrome b5/cytochrome b5 reductase complex in the form of NADH-linked aquacobalamin reductase were studied. The inhibition studies with cobalamin analogues suggested that hydrophobicity of the corrin ring of cobalamin molecule is involved in binding of cobalamin to the cytochrome b5/cytochrome b5 reductase complex.

Animals↗

PubMed1992

DNA relatedness among Erysipelothrix rhusiopathiae strains representing all twenty-three serovars and Erysipelothrix tonsillarum.

The levels of relatedness among strains of Erysipelothrix rhusiopathiae (serovars 1 through 23 and type N) were estimated by performing DNA-DNA hybridization experiments with the type strains of E. rhusiopathiae and Erysipelothrix tonsillarum, which are the two Erysipelothrix species that have been described. Two distinct DNA relatedness groups were identified. The group 1 strains, representing serovars 1, 2, 4 through 6, 8, 9, 11, 12, 15 through 17, 19, and 21 and type N, exhibited more than 73% hybridization with the type strain of E. rhusiopathiae but less than 24% hybridization with the type strain of E. tonsillarum. Group 2 included serovar 3, 7, 10, 14, 20, 22, and 23 strains, and these strains exhibited more than 66% hybridization with the type strain of E. tonsillarum but less than 27% hybridization with the type strain of E. rhusiopathiae. Strains representing serovars 13 and 18 exhibited low levels of hybridization (16 to 47%) with both of the type strains, indicating that these serovars may be members of a new genomic species. The members of the E. rhusiopathiae and E. tonsillarum groups resembled each other in many phenotypic characteristics, but differed in their ability to produce acid from saccharose and in their pathogenicity for swine. Our results confirm that the genus Erysipelothrix contains two main genomic species, E. rhusiopathiae and E. tonsillarum, which can be differentiated into serovars.

Animals↗

PubMed1992

Antigenic analysis of Clostridium chauvoei flagella with protective and non-protective monoclonal antibodies.

Five monoclonal antibodies (mAbs) directed against the flagellin of Clostridium chauvoei were used to analyse the structural and antigenic characteristics on the bacterial flagellar surface. Immune electron microscopy showed that three protective mAbs recognized the surfaced-exposed epitopes on the flagellar filament of this bacteria. In contrast, two non-protective mAbs recognized internal epitopes of the flagellar filament. These findings have been confirmed by ELISA using mAbs absorbed with whole cells of C. chauvoei possessing flagella. Competitive binding assays showed that protective mAbs indicated reciprocal competition, while each of the non-protective mAbs had topographically distinct epitopes. Moreover, immunoblotting analysis with cyanogen-bromide-cleaved flagellin showed that protective mAbs may preferentially recognize conformational epitopes, whilst one of the non-protective mAbs may recognize a linear and conformation-independent epitope in the flagellin of C. chauvoei.

Antibodies, Monoclonal↗

PubMed1992

Cytokine production in patients with inflammatory bowel disease.

The production of cytokines in peripheral blood mononuclear leukocytes of patients with inflammatory bowel disease was investigated. T cell subset analysis and differential white blood cell counts were also performed. Thirty five patients with ulcerative colitis, 14 with Crohn's disease, and 15 age matched healthy volunteers were studied. No differences were observed in T cell subsets and OKT4/OKT8 ratios in patients with ulcerative colitis or Crohn's disease compared with controls. Interleukin 1 beta production was significantly increased in active ulcerative colitis and Crohn's disease, compared with values in controls, but returned to control levels in the inactive stages. In addition, in active ulcerative colitis and Crohn's disease, there were significant correlations between the interleukin 1 beta production and the ulcerative colitis activity index or Crohn's disease activity index. Interleukin 2 production was also significantly increased in the active ulcerative colitis and significantly correlated to the activity index, but there was no change in Crohn's disease patients compared with controls. Gamma interferon production in patients was the same as that in controls. This study suggests that the interleukin 1 beta and 2 values in peripheral mononuclear leukocytes of active untreated inflammatory bowel disease are indicators of the disease states of ulcerative colitis or Crohn's disease, or both.

Acute Disease↗

PubMed1992

Modification of water and electrolyte metabolism during head-down tilting by hypoglycemia in men.

The effect of hypoglycemic stress on the changes in water and electrolyte metabolism induced by head-down tilting (HDT) was studied. Six healthy men were subjected to postural changes (30 min standing, 2 h HDT, 1 h standing), with or without the intravenous administration of insulin at the beginning of HDT. When insulin was not given, antidiuretic hormone (ADH), cortisol, plasma renin activity (PRA), aldosterone, and catecholamine levels were decreased and atrial natriuretic polypeptide (ANP) levels increased during HDT. These changes were associated with 2.5- and 1.5-fold increases in urine flow and sodium excretion, respectively, when compared with the amounts before HDT. On the other hand, insulin-induced hypoglycemia during HDT produced increases in ADH, cortisol, PRA, aldosterone, and catecholamine levels. At the same time, an exaggerated ANP response by HDT was observed. These hormonal changes were associated with an abolishment of the increases in urine flow and sodium excretion. It is suggested that acute stress modifies the changes in fluid and electrolyte metabolism induced by HDT.

Adult↗

PubMed1992

Synthesis of a potent rhodomycin, oxaunomycin, and its analogs.

Oxaunomycin (3) and its regioisomer (6) were synthesized by employing regioselective glycosidations of the C-7 hydroxyl group of 10-O-acetyl-beta-rhodomycinone (16) and the C-10 hydroxyl group of the C-7,9-O-phenylboronate (14), respectively, in the presence of trimethylsilyl trifluoromethanesulfonate. Under the Königs-Knorr conditions, 16 was also glycosidated to provide a fluoro sugar analog (7).

Anthracyclines↗

PubMed1992

Intravascular ultrasound imaging in human peripheral and coronary arteries in vivo.

To determine the feasibility of intravascular ultrasound imaging in vivo, a miniaturized high frequency transducer catheter was introduced into human peripheral (n = 10) and coronary (n = 4) arteries. Cross-sectional ultrasound images were obtained from iliofemoral arteries in 10 patients using a 20 MHz transducer catheter (1.2 mm in diameter) and from coronary arteries in 4 patients using a 30 MHz transducer catheter 5 French size (Fr) following successful coronary angioplasty. Ultrasound images obtained from peripheral arteries showed a three-layered appearance (echo-reflective intima, echo-lucent media and echo-reflective adventitia) in the normal arteries. In diseased arteries, the location, amount and extent of atheromatous plaque were clearly documented. The arterial diameters measured by ultrasound closely correlated with the measurements by angiography (r = 0.91) in the peripheral arteries. Coronary angiograms obtained following balloon angioplasty revealed smooth edges at the dilatation sites without significant narrowing in all patients. However, a significant amount of residual atheromatous plaque was clearly observed on the ultrasound images at the previously dilated sites. Coronary dissection, which was identified as an echo-lucent area behind the plaque, was noted in 2 patients. Ultrasound images also revealed the presence of calcium in the plaque which was unrecognized on the angiograms in 3 patients. In addition, direct measurement of the lumen cross-sectional area was possible on the ultrasound images.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriosclerosis↗