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Biomedical subjects

H Okuda

Publications and source records attributed to H Okuda.

At least 289 records · Page 16Linked to original sources
PubMed1988

Purification of rat kidney carboxylesterase and its comparison with other tissue esterases.

Carboxylesterase was purified from rat kidney in an electrophoretically homogeneous form by acetone precipitation, followed by successive chromatographies on DEAE-cellulose and hydroxyapatite and then isoelectric focusing. The purified enzyme catalyzed the hydrolyses of monoacylglycerols and short-chain triacylglycerols, such as tributyrin, but not the hydrolysis of long-chain triacylglycerol. Its optimum pH with methyl butyrate as a substrate was 8.0. The relation of its activity to the methyl butyrate concentration differed from those for pancreatic lipase and liver esterase, and also from those for lipolytic enzymes from various other tissues. The relations of methyl butyrate-hydrolyzing activity with methyl butyrate concentration were compared among various carboxylester hydrolyzing enzymes. Based on the results, these enzymes were classified into four classes.

Animals↗
PubMed1988

Ca2+ uptake in bovine adrenocortical microsomes: formation of phosphorylated intermediate of Ca2+ dependent ATPase.

Bovine adrenocortical microsomes were prepared and partially purified by discontinuous sucrose density gradient. Light fractions of the microsomes at the interface between 15 and 30% sucrose solution, exhibited ATP dependent Ca2+ uptake. The Ca2+ uptake was dependent on temperature and stimulated by free Ca2+ (the concentration for half maximal activation = 1.0 microM) and Mg2+. The Ca2+ uptake was inhibited by ADP but not affected by 10 mM NaN3 or 0.5 mM ouabain. Calcium release from the microsomes was accelerated by a Ca2+ ionophore, A23187, but not by a Ca2+ antagonist, diltiazem. A microsomal protein with a molecular weight of 100-110 kDa was phosphorylated by [gamma-32P]ATP in the presence of Ca2+, and the Ca2+ dependency was over the same range as the Ca2+ uptake (the concentration for half maximal activation = 3.0 microM). The phosphorylated protein (EP) was stable at acidic pH but labile at alkaline pH and sensitive to hydroxylamine. The rate of EP formation at 0 degrees C in the presence of 1 microM ATP and 10 microM Ca2+ (half time = 0.2 s) was less than that in the sarcoplasmic reticulum (SR) of rabbit skeletal muscle (half time = 0.1 s). The rate of EP decomposition at 0 degrees C after adding EGTA was about 6.7 times slower (rate constant: kd = 4.3 X 10(-3) s-1) than that of SR. It was suggested that adrenocortical microsomes contain a Ca2+ dependent ATPase which function as a Ca2+ pump with similar properties to that of SR.

Adenosine Diphosphate↗
PubMed1988

Acute effects of sodium valproate on epileptic photosensitivity in the lateral geniculate-kindled cat.

Epileptic photosensitivity was acquired as a result of kindling in the lateral geniculate body (GL), and a GL-kindled cat pretreated with DL-allylglycine was found to be a useful model of epilepsy for assessing the efficacy of anticonvulsant drugs. In the present study the acute anticonvulsant effects of sodium valproate (VPA) were examined in the GL-kindled cat under DL-allylglycine. An intravenous injection of VPA at 50 mg/kg induced a protective action against photically induced seizures and paroxysmal EEG activities. This protection persisted for up to 4 hours of the observation period and corresponded to plasma concentrations (61 to 123 micrograms/ml) similar to those considered therapeutic in humans. The present findings are consistent with those obtained in other animal models of photosensitive epilepsy, and lend experimental support to the idea that VPA possesses antiepileptic activity in human photosensitive epilepsy.

Amygdala↗
PubMed1988

Effects of various ginseng saponins on 5-hydroxytryptamine release and aggregation in human platelets.

The effects of various ginseng saponins isolated from red ginseng roots, on aggregation and 5-hydroxytryptamine release (5-HT) human platelets have been investigated. Among the six saponins tested, only ginsenoside Rg1 inhibited adrenaline- and thrombin-induced platelet aggregation and 5-HT release dose-dependently, at concentrations of 5 to 500 micrograms ML-1. Ginsenoside Rg1 had no effect on adrenaline- and thrombin-induced arachidonic acid release and diacylglycerol production. But it did reduce the elevation of cytosolic free calcium concentration (Ca2+)i shown in the second phase induced by adrenaline and thrombin, at concentrations of 10 to 500 micrograms mL-1. Those data suggest that the inhibitory effects of ginsenoside Rg1 on 5-HT release from, and aggregation of, platelets might be due to the reduction of (Ca2+)i elevation at the second phase induced by adrenaline and thrombin. The results suggest that ginsenoside Rg1 in red ginseng roots may be active as a drug in the treatment of artheroscleorosis and thrombosis.

Arachidonic Acids↗
PubMed1988

Bile acid secretion and pool size during phenobarbital induced hypercholeresis.

An increase in bile flow after phenobarbital administration occurs in the rat and other species; however, the mechanism(s) of the choleretic effect is incompletely understood and the role of the increase in liver weight is controversial. We therefore measured bile flow, bile acid secretion and pool size in male Sprague-Dawley rats pretreated with phenobarbital (75 mg/kg/day) for 6 days; liver weight, liver cell volume and DNA content were also evaluated. Phenobarbital treatment increased liver weight and mean hepatocyte volume by 39 and 26%, respectively, while total DNA content did not change, thus indicating that the hepatomegaly results principally from hypertrophy rather than hyperplasia. Bile flow was significantly higher in treated rats when expressed per unit of body weight (64.6 +/- 2.4 (S.E.) vs 53.3 +/- 1.6 microliter/min/kg; P less than 0.05) but was unchanged when expressed per gram of liver (1.40 +/- 0.04 vs 1.37 +/- 0.06 microliter/min/g; P greater than 0.5). The initial bile acid secretion rate and pool size were both significantly reduced in the phenobarbital group compared to controls (1224.2 +/- 110.4 vs 1656.6 +/- 163.2 nmol/kg/min and 562.8 +/- 41.5 vs 814.3 +/- 78.3 mumol/kg; both P less than 0.05), whereas the basal synthetic rate was unchanged. These findings suggest that the enlarged, phenobarbital-treated hepatocyte produces more bile than the normal cell, despite the decreased secretion of bile acids. Therefore, the drug-induced choleresis involves a selective increase in the bile acid-independent fraction of bile flow.

Animals↗
PubMed1987

Effects of baicalein on leukotriene biosynthesis and degranulation in human polymorphonuclear leukocytes.

Studies were made on the effects of baicalein (5,6,7-trihydroxyflavone) on leukotrienes B4 and C4 biosyntheses and degranulation induced by calcium ionophore A23187 (A23187) in human polymorphonuclear leukocytes. Baicalein inhibited A23187-induced biosynthesis of leukotrienes B4 and C4 in human polymorphonuclear leukocytes. The concentration of baicalein required for 50% inhibition (IC50) of leukotrienes B4 and C4 formations was 1.46.10(-6) and 6.00.10(-7) M, respectively, using 1.0 microgram/ml of A23187. In addition, baicalein dose-dependently inhibited beta-glucuronidase and lysozyme releases induced by A23187, leukotriene B4 plus cytochalasin B and platelet-activating factor plus cytochalasin B. Furthermore, baicalein was found to inhibit dose-dependently Ca2+ uptake into the cells and Ca2+ mobilization from the intracellular stores.

Calcimycin↗
PubMed1987

Long-chained 1-mercapto-n-alkanes as potent inhibitors toward liver alcohol dehydrogenase.

Long-chained 1-mercapto-n-alkanes showed potent inhibitory effects on horse liver alcohol dehydrogenase (HLADH). The inhibitory effect of the thiols was enhanced by increasing the number of the alkyl carbon atoms up to 10-12 and steeply lowered by further increase in the carbon number. The HLADH activity was almost completely inhibited in competitive manner by an equivalent concentration of 1-mercapto-n-decane or -n-dodecane to that of the subunit of the dimeric zinc enzyme; inhibition constant Ki was 0.55 nM for the former. The present study strongly suggests that the thiols interact simultaneously with at least two sites of HLADH; the primary one could be the zinc atom in the active site of the enzyme, interacting with the sulfhydryl groups, and the other a hydrophobic binding site for the their alkyl carbons.

Alcohol Dehydrogenase↗
PubMed1987

Usefulness of carcinoembryonic antigen measurement in feces of patients with colorectal cancer.

Anticarcinoembryonic antigen (CEA) antisera which showed no reactions with normal adult feces were prepared in guinea pigs. Using these, levels of CEA in feces from patients with colorectal carcinoma were measured by gel diffusion and rocket immunoelectrophoresis. Sixteen of 22 (73 percent) patients with carcinoma of the colon or rectum (Dukes' A4/6, B6/8, C6/7, D0/1) had detectable CEA in their feces, while none was detected in the feces of four patients with gastric ulcers or in those of 22 normal volunteers. Five of the 16 fecal CEA-positive patients showed no elevation of plasma CEA levels. Measurements using a commercial CEA kit (Abbott Laboratories) could not detect the differences between fecal CEA values of patients with colorectal carcinoma and benign diseases, or those of normal volunteers. These results suggest that measurement of fecal CEA by specific anti-CEA antisera will be valuable in screening and diagnosis of colorectal carcinoma.

Carcinoembryonic Antigen↗
PubMed1987

Effect of isoproterenol on myocardial mechanical function and cyclic AMP content in the fetal rabbit.

The effect of isoproterenol on mechanical function was studied in the isolated arterially perfused heart of the fetal (21st and 28th day of gestation) and newborn rabbits. The inotropic effect of isoproterenol in the fetus was less than in the newborn. In contrast, myocardial cyclic AMP levels after isoproterenol infusion in the fetus were greater than in the newborn. The inotropic effects of dibutyryl cyclic AMP and of calcium in the fetus were less than in the newborn. These data suggest that the process from beta-receptor to cyclic AMP in the fetus was equally or even more responsive to isoproterenol than in the newborn. The diminished inotropic effect of isoproterenol in the fetus may be due, at least in part, to the decreased inotropic effect of calcium.

Animals↗
PubMed1987

Production of abnormal prothrombin (des-gamma-carboxy prothrombin) by hepatocellular carcinoma. A clinical and experimental study.

We measured plasma abnormal prothrombin (des-gamma-carboxy prothrombin; DCP) levels in normal subjects and in patients with hepatocellular carcinoma and other various diseases using the enzyme-linked immunosorbent assay developed by Motohara et al. (Pediatr Res 1985; 19: 354-357). Fifty-eight percent of 52 patients with hepatocellular carcinoma had elevated DCP levels; 24 of 28 patients with advanced or moderately advanced hepatocellular carcinoma were positive. By contrast, 50 normal controls, 13 pregnant women and 10 patients with acute hepatitis had normal levels. Three of 55 patients with chronic liver disease, and 6 of 32 patients with other malignancies, showed a slight increase. Thus, increased plasma DCP appears useful for the diagnosis of hepatocellular carcinoma. To elucidate the mechanism for the increase of DCP in hepatocellular carcinoma, we cultured a human hepatoma cell line, huH-2, and measured the levels of this abnormal prothrombin in the medium. The huH-2 cells produced large amounts of DCP in the medium without added vitamin K. It increased in a cell concentration- and time-dependent fashion. These cells produced no detectable amount of DCP in the medium with added vitamin K. Thus, human hepatoma cell line huH-2 produces DCP, and its production is dependent on the amount of vitamin K available in the medium. Des-gamma-carboxy prothrombin may be a useful tumor marker for the diagnosis of hepatocellular carcinoma.

Biomarkers↗