Biomedical subjects

S Horie

Publications and source records attributed to S Horie.

At least 163 records · Page 9Linked to original sources

PubMed1990

Different regulation of hepatic peroxisomal beta-oxidation activity in rats treated with clofibrate and partially hydrogenated marine oil.

Total RNAs from the livers of rats treated with clofibrate and partially hydrogenated marine oil (PHMO) were translated in a reticulocyte-lysate cell-free protein-synthesizing system. In clofibrate-treated rats, mRNA activity for acyl-CoA oxidase (AO), the rate-limiting enzyme of the peroxisomal beta-oxidation system, was increased markedly compared with the control, whereas the increase was less than 2-fold in PHMO-treated rats. When rats were treated with both clofibrate and PHMO in vivo, an additional increase in the hepatic AO activity was observed compared with either treatment alone, suggesting that increases in the activities of peroxisomal beta-oxidation in the rats treated with clofibrate and PHMO are based on two distinct mechanisms.

Acyl-CoA Oxidase↗

PubMed1990

Cytochrome P-450scc-catalyzed production of progesterone from 22R-hydroxycholest-4-en-3-one by way of 20,22-dihydroxycholest-4-en-3-one.

Transient accumulation of a dihydroxylated steroid was found when 22R-hydroxycholest-4-en-3-one was used as the substrate for a reconstituted cholesterol side-chain cleavage system derived from bovine adrenocortical mitochondria. The indications were that the accumulated steroid was an intermediate in the cytochrome P-450scc-catalyzed reaction. The retention time of the accumulated intermediate was identical with that of authentic 20,22-dihydroxycholest-4-en-3-one on HPLC. When 22R-hydroxycholesterol and 22R-hydroxycholest-4-en-3-one were incubated simultaneously, the total amount of reaction products was essentially the same as that observed with 22R-hydroxycholest-4-en-3-one alone. Under the conditions employed, the apparent turnover number of cytochrome P-450scc for 22R-hydroxycholesterol was calculated to be 77 nmol/min/nmol P-450 from the amount of pregnenolone formed, whereas the apparent turnover number for 22R-hydroxycholest-4-en-3-one was 64 nmol/min/nmol P-450 with respect to the intermediate formation and 77 nmol/min/nmol P-450 with respect to the progesterone formation. The apparent turnover number for 20,22-dihydroxycholest-4-en-3-one was about 125 nmol/min/nmol P-450, which was not significantly different from that of 20,22-dihydroxycholesterol. The apparent Km for 22R-hydroxycholesterol was about 20 microM and those for 22R-hydroxycholest-4-en-3-one and 20,22-dihydroxycholest-4-en-3-one were 50 and 40 microM, respectively. Thus, 22R-hydroxycholest-4-en-3-one was efficiently metabolized to progesterone by way of 20,22-dihydroxycholest-4-en-3-one by cytochrome P-450scc.

Adrenal Glands↗

PubMed1990

Long-term consequence of nephrectomy.

Renal function and blood pressure were assessed in 139 patients after unilateral nephrectomy. Followup ranged from 1 to 57 years, with a mean of 13.0 +/- 1.1 (standard error). Serum creatinine, creatinine clearance, beta 2-microglobulin clearance and blood pressure remained stable during followup. No significant effect of years after unilateral nephrectomy, blood pressure or cause of nephrectomy was observed on creatinine clearance. However, urine excretion of protein (correlation coefficient 0.475, p less than 0.01) and N-acetyl-beta-D-glucosaminidase (correlation coefficient 0.464, p less than 0.01) increased as a function of years after unilateral nephrectomy. Creatinine clearance tended to be low in elderly patients or patients who underwent nephrectomy at an advanced age. Our studies show that despite the late development of proteinuria and tubular injury, unilateral nephrectomy is not associated with deterioration in kidney function or elevation of blood pressure during long-term followup.

Acetylglucosaminidase↗

PubMed1990

Laser ureterolithotripsy with combined rigid and flexible ureterorenoscopy.

Because the pulsed dye laser can be transmitted through a thin, flexible quartz fiber a small caliber ureteroscope and flexible ureterorenoscope are applicable. Therefore, the use of a rigid or flexible ureterorenoscope was combined with laser lithotripsy to treat upper urinary tract calculi. All 14 ureteral stones below the pelvic brim were removed successfully with a rigid 7.2F (outer diameter) ureteroscope and 14 of 16 stones above the pelvic brim were removed with a flexible ureterorenoscope. Laser monotherapy was effective in 24 cases and the complementary use of forceps or electrohydraulic lithotripsy was required in 4. Two stones were lost from the visual field during endoscopic manipulation. There was no complication requiring surgical correction. The combined use of these instruments is highly successful and safe for the treatment of upper urinary tract calculi.

Adult↗

PubMed1990

Preincubation in acid medium increases Na/H antiporter activity in cultured renal proximal tubule cells.

Chronic acidosis in vivo leads to an increase in proximal tubule Na/H antiporter activity that persists when the transporter is studied out of the acidotic environment. It is presently not clear whether a decrease in extracellular fluid pH alone is sufficient to elicit this adaptation. The present studies examined the effect of acid preincubation on Na/H antiporter activity in cultured proximal tubule cells. Antiporter activity was examined after a 2-day preincubation in control or acid medium, 1 hr after removal from the preincubation fluid. Na/H antiporter activity was assayed as the initial rate of Na-dependent alkalinization after cell acidification in the absence of CO2/HCO3. Preincubation in low [HCO3] acid medium or in high PCO2 acid medium led to increases in amiloride-sensitive Na/H antiporter activity. This adaptation was inhibited by addition of cycloheximide to the preincubation medium. Preincubation of fibroblasts in low [HCO3] acid medium did not lead to increased Na/H antiporter activity but rather caused a small inhibition. These studies demonstrate an adaptation in Na/H antiporter activity elicited by a low pH of the extracellular fluid, which is dependent on protein synthesis, and may be unique to certain H/HCO3-transporting epithelia.

Amiloride↗

PubMed1990

Centrally mediated inhibitory effect of 5-[2-(diethylamino)ethyl]amino-5,11-dihydro[1]benzoxepino[3,4- b]pyridine trihydrochloride (KW-5805) on gastric acid secretion in rats.

KW-5805, 5-[2-(diethylamino)ethyl]amino-5,11-dihydro[1]benzoxepino[3,4- b]pyridine trihydrochloride, is a new tricyclic compound with antiulcer activities. Its effect on stimulated gastric acid secretion was investigated in the perfused stomach of anesthetized rats. KW-5805 at 0.3-10 mg/kg, i.v., dose-dependently inhibited gastric acid secretion stimulated by 2-deoxy-D-glucose (2-DG). On the other hand, the compound at 10-20 mg/kg, i.v., exerted a moderate decrease in gastric acid secretion stimulated by bethanechol; and at 10 mg/kg, i.v., it produced no change in gastric acid secretion evoked peripherally by vagal electrical stimulation. When applied intracerebroventricularly at 1-5 micrograms/rat, this compound dose-relatedly reduced gastric acid secretion stimulated by 2-DG. Three main metabolites (KF-10504, KF-9530 and KF-10847) of KW-5805 at 1 mg/kg, i.v., caused no significant decrease in gastric acid secretion stimulated by 2-DG. Doxepin, a tricyclic compound, definitely depressed the 2-DG stimulated gastric acid secretion at 1 mg/kg, i.v. It is suggested that intravenous administration of KW-5805 inhibits gastric acid secretion stimulated by 2-DG, mainly via centrally mediated mechanisms, and that biotransformation of KW-5805 to the metabolites contributes little to the development of the antisecretory effect.

Animals↗

PubMed1990

[Idiopathic thrombocytopenic purpura complicated with circulating lupus anticoagulant].

A 37 year-old female was admitted to our hospital because of hypermenorrhea, prolonged bleeding time, thrombocytopenia and the diagnosis of idiopathic thrombocytopenic purpura (ITP) was made. Though activated partial thromboplastin time (APTT) was markedly prolonged, her coagulation factors were within normal ranges. Activities of the circulating lupus anticoagulant (LAC) was suggested. Kaolin clotting time of the platelet poor plasma was used as a sensitive screening test using the mixture of normal and patient's plasma for the detect of LAC. As a result, LAC positive pattern was observed. The treatment with high-dose gammaglobulin brought out a transient increase of the platelet count, but the prolongation of APTT was not corrected. Both the platelet count and the prolongation of APTT were significantly improved after the treatment with betamethasone.

Adult↗

PubMed1990

Advances in research on DT-diaphorase--catalytic properties, regulation of activity and significance in the detoxication of foreign compounds.

DT-diaphorase [NAD(P)H dehydrogenase (quinone), EC 1.6.99.2] is a flavoprotein enzyme widely distributed in the cytosolic fractions of various animal tissues. It is also called menadione reductase or NAD(P)H-quinone reductase and catalyzes NAD(P)H-dependent 1-, 2- or 4-electron reduction of certain redox dyes, aromatic nitro compounds, aromatic C-nitroso compounds and probably azo-dyes, as well as menadione (vitamin K3) and other quinones. Dicumarol exerts characteristic inhibition on DT-diaphorase, whereas serum albumin and certain non-ionic detergents exert activation. Excessive concentrations of many of the electron acceptors inhibit the activity of this enzyme. The physiological significance of DT-diaphorase is still obscure because the physiological vitamins (K1 and K2) and coenzyme Q10 are difficult to reduce with this enzyme. Results of recent studies suggest that DT-diaphorase prevents formation of active oxygen species. Activities in liver and other tissues are known to be enhanced by administration of chemicals including certain carcinogens such as 3-methylcholanthrene (3-MC), anti-oxidants such as 3-tert-butyl-4-hydroxyanisole (BHA), and other compounds. Both basal and induced activities vary considerably with tissue, sex, strain and species of animals. The strain variations in activities in rat and mouse liver are known to be inherited, and the trait of hereditary transmission can be adequately explained by postulating two loci of genes or gene clusters regulating the activity. Resistance of animals to various toxic or carcinogenic substances may be promoted by BHA administration and depressed by dicumarol administration. Thus, attention has been focused on the role played by DT-diaphorase in the detoxication of foreign compounds. Knowledge on strain variations in basal and induced activities of tissue DT-diaphorase is of potential value when choosing a rat or mouse strain suitable for studying the toxic effects of drugs, especially drugs expected to be detoxified by reductive metabolism. With future progress in research on DT-diaphorase, this enzyme might be applied to prophylactic and therapeutic medicine.

Animals↗

PubMed1990

Increasing effect of sodium 3-ethyl-7-isopropyl-1-azulenesulfonate 1/3 hydrate (KT1-32), a novel antiulcer agent, on gastric mucosal blood flow in anesthetized.

Effect of a novel azulene derivative KT1-32 on gastric mucosal blood flow (GMBF) was studied to elucidate its mucosal defensive mechanisms underlying the antiulcer action. The GMBF was measured by two methods which were based on heat clearance and laser Doppler velocimetry in the rat. Intravenous administration of KT1-32 produced a dose-dependent increase in GMBF at doses of 0.3-10 mg/kg; significant increases in GMBF were observed at doses not less than 1 or 3 mg/kg by the laser Doppler or heat clearance method, respectively. The duration of action was about 10 min at 10 mg/kg of KT1-32. A good parallelism in these GMBF changes was noted between both methods. Cetraxate, an antiulcer agent, elicited an increase in GMBF at 30 mg/kg, i.v., when GMBF was measured by the heat clearance method. Sodium guaiazulene 3-sulfonate, another azulene antiulcer agent, showed no increase in GMBF. It is suggested that the increasing effect of KT1-32 on GMBF contributes to its antiulcer activity through strengthening mucosal defensive mechanisms.

Anesthesia↗

PubMed1989

Sensitive assay of cytochrome P450scc activity by high-performance liquid chromatography.

We have developed a simple procedure for analyzing the reaction intermediates and product of the cholesterol side-chain cleavage system by high-performance liquid chromatography with uv absorption monitoring. After the cholesterol side-chain cleavage system had been incubated and the reaction then halted by heat treatment, the product was converted into 3-one-4-en steroid showing intense absorption at 240 nm upon reaction with cholesterol oxidase. The converted steroids were then analyzed by normal-phase HPLC. In consequence, the catalytic activity of the reconstituted adrenocortical cytochrome P450scc system was readily assayed with a sensitivity more than 10-fold higher by this conversion. Also, it was shown that 22R-hydroxy-cholest-4-en-3-one could serve as a good substrate for cytochrome P450scc and that the 20R,22R-dihydroxy derivative could be clearly detected as a reaction intermediate in the reconstituted system.

Animals↗

PubMed1989

Participation of peroxisomes in lipid biosynthesis in the harderian gland of guinea pig.

Peroxisomal enzyme activities in the guinea-pig harderian gland, which has a unique lipid composition, were studied. Activities of catalase, acyl-CoA oxidase and the cyanide-insensitive acyl-CoA beta-oxidation system in this tissue were comparable with those in rat liver. The activities of dihydroxyacetone phosphate acyltransferase (DHAPAT, EC 2.3.1.42) and alkyl-DHAP synthase (EC 2.5.1.26) were appreciable, and the distributions of both activities were consistent with that of sedimentable catalase activity. Glycerol-3-phosphate acyltransferase (GPAT, EC 2.3.1.15), which is localized in both microsomes (microsomal fractions) and mitochondria in the rat liver, was a peroxisomal enzyme in the harderian gland, though the activity was only about one-tenth of the DHAPAT activity. These enzymes had different pH profiles and substrate specificity. The existence of high activities of enzymes of the acyl-DHAP pathway in peroxisomes suggests the physiological significance of peroxisomes in the biosynthesis of glycerol ether phospholipid and 1-alkyl-2,3-diacylglycerol in the guinea-pig harderian gland.

Acyltransferases↗

PubMed1989

Multiple molecular forms of cytochrome P-450SCC purified from bovine corpus luteum mitochondria.

Cytochrome P-450 related to side-chain cleavage of cholesterol (P-450SCC) was isolated from bovine corpus luteum mitochondria in the form of its stable cholesterol complex. The isolation procedure included ammonium sulfate fractionation and chromatography on omega-aminohexyl-Sepharose (AH-Sepharose). Corpus luteum P-450SCC was resolved into one minor (AH-I) and two major (AH-II and AH-III) fractions by the chromatography. Results of re-chromatography suggested the possibility that AH-III Fraction was originally complexed with lipidic material. The two major fractions purified by the re-chromatography (AH-IIR and AH-IIIR Fractions) showed essentially a single band on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and their absorption spectra were indistinguishable from each other. Both fractions were further resolved into two major and some minor bands of P-450SCC by isoelectric focusing on polyacrylamide gel in the presence of a non-ionic detergent, as detected by protein staining, heme staining and immunoblot analysis with anti-bovine P-450SCC monoclonal antibody. Both AH-IIR and AH-IIIR Fractions were further resolved by high-performance liquid chromatography (HPLC) on SP-TSK gel column into two fractions, SP-I and SP-II. These fractions had the same N-terminal amino acid sequence, showed similar catalytic activity and resolved into one major and a few minor bands on isoelectric focusing on polyacrylamide gel. Much more heterogeneity was observed in purified P-450SCC preparations from bovine adrenal cortex mitochondria. These results indicated the presence of multiple molecular forms of corpus luteum P-450SCC as well as adrenal cortex P-450SCC. Computer simulation studies were carried out in order to analyze the mechanism of formation of multiple bands on isoelectric focusing. The multiple bands of corpus luteum P-450SCC could be explained by postulating the presence of two isozymes (or molecular forms) having a pair of sites each with or without a charged group.

Adrenal Cortex↗

PubMed1989

Species differences in the effects of bezafibrate, a hypolipidemic agent, on hepatic peroxisome-associated enzymes.

The effects of bezafibrate on hepatic peroxisome-associated enzymes of rats, mice, guinea pigs, hamsters, rabbits, dogs and monkeys were examined. Dogs and monkeys were given bezafibrate orally at 30 mg/kg body wt daily for 2 weeks and at 125 mg/kg body wt daily for 13 weeks, respectively, and other species at 100 mg/kg daily for 2 weeks. In male rats, marked changes were observed in the activities of catalase (1.73-fold), D-amino acid oxidase (DAAO; 0.56-fold), fatty acyl-CoA oxidizing system (FAOS; 12.9-fold) and carnitine acetyltransferase (CAT; 35.8-fold); in female rats, the changes were less than in the males. In mice, there were no apparent sex differences in the responses of hepatic peroxisomal enzymes to bezafibrate and the increases in the activities of catalase, FAOS and CAT were 1.76-, 3.75- and 7.94-fold respectively. In guinea pigs, only slight increases in the activities of FAOS (3.00-fold) and CAT (2.83-fold) were observed. In hamsters, the increases in catalase, FAOS and CAT activities, were 1.23-, 2.19- and 2.77-fold respectively. Although rabbits and dogs showed slight increases in CAT activity, no significant response to the drug was observed in monkeys. Hepatomegaly and the increase of hepatic content of peroxisome proliferation-associated polypeptide (PPA-80), which has been recognized as a peroxisomal bifunctional protein in the fatty acid beta-oxidation pathway, were observed only in rats and mice. These results show that there were marked species differences in the effects of bezafibrate on hepatic peroxisomes, and that bezafibrate induced hepatic peroxisome proliferation in rodents, especially rats and mice.

Animals↗

PubMed1989

Turnover of fatty acyl-CoA oxidase in the liver of rats fed on a partially hydrogenated marine oil.

The change in turnover of fatty acyl-CoA oxidase (FAO), the rate-limiting enzyme of the peroxisomal beta-oxidation system, was investigated in rats fed a 30% (w/w) partially hydrogenated marine oil (PHMO) diet. The FAO activity increased five-fold after two weeks of PHMO feeding, and decreased after withdrawal of the diet. Based on in vivo experiments using L-[4,5-3H]leucine and an immunoprecipitation technique, the increase in the activity of FAO could be accounted for by a 1.6-fold higher rate of FAO synthesis and a 3.4-fold slower rate of FAO degradation as compared to controls. In the same PHMO-fed rats, the rates of synthesis and degradation of carnitine palmitoyltransferase were 1.8-fold higher and 2.0-fold slower, respectively, as compared to controls. The results indicate that the observed increase in the activity of the enzymes of peroxisomal beta-oxidation is mainly due to a reduced rate of FAO degradation in the liver of rats fed the PHMO diet.

Acyl-CoA Oxidase↗

PubMed1989

Existence of acetyl-CoA-dependent chain elongation system in hepatic peroxisomes of rat: effects of clofibrate and di-(2-ethylhexyl)phthalate on the activity.

The acetyl-CoA-dependent elongation of medium-chain acyl-CoA in the presence of pyridine nucleotide was studied in rat liver. The activity was increased by the administration of peroxisome proliferators, clofibrate and di-(2-ethylhexyl)phthalate, and the change was more remarkable in peroxisomes than in mitochondria. Addition of 0.01% Triton X-100 to the incubation mixture caused an increase in the mitochondrial activity, whereas the peroxisomal activity did not increase significantly. The pH optimum for the peroxisomal activity was in the range of pH 6.5-7.0 and that for the mitochondrial activity was pH 7.5-8.0. The specificities of primer chain length in both organelles were almost the same, and octanoyl-CoA was the preferred substrate. Peroxisomal activity was completely inhibited by the addition of 1 mM N-ethylmaleimide or 1 mM p-hydroxymercuribenzoic acid, while the activity did not change on the addition of 1 mM KCN or an antibody to acyl-CoA oxidase, the first enzyme of the peroxisomal beta-oxidation system. The activity of enoyl-CoA reductase, which catalyzes the last step of the elongation system, was also detected in peroxisomes, although the main activity was localized in microsomes. When the liver peroxisomal fraction of clofibrate-treated rats was incubated with a mixture of octanoyl-CoA, acetyl-CoA, NADH, NADPH, and Triton X-100 in a buffer system, dodecanoyl-CoA was detected as the main product by radio-gas chromatography. On the other hand, the elongation activity was decreased greatly by the addition of NAD+ into the mixture. These results indicate that (i) peroxisomes have activity to elongate medium chain acyl-CoA; (ii) the peroxisomal elongation system may consist of the reverse reaction of the beta-oxidation system except for the last step, which is catalyzed by enoyl-CoA reductase; and (iii) the peroxisomal elongation system is less active than the beta-oxidation system under physiological conditions.

Acetyl Coenzyme A↗

PubMed1989

Identity of acyl-CoA oxidase with glutaryl-CoA oxidase.

Rats fed on clofibrate- and DEHP-containing diets showed virtually proportional increases in hepatic acyl-CoA oxidase and glutaryl-CoA oxidase activities. The solubilization profiles of the two activities from the light mitochondrial fraction of the liver homogenate of DEHP-treated rats were the same, and the glutaryl-CoA oxidase/acyl-CoA oxidase activity ratio remained constant through the purification. The final preparation obtained was a single protein based on the result of polyacrylamide gel electrophoresis. The evidence indicates that the two activities are associated with the same protein.

Acyl-CoA Oxidase↗

PubMed1989

Mouse strain variations in the magnitude of induction of liver DT-diaphorase and hereditary transmission of the trait.

1. Strain variations among mice in terms of cytosolic DT-diaphorase activity were studied in liver, kidney, stomach and heart tissues with or without the administration of 3-tert-butyl-4-hydroxyanisole (BHA). 2. BHA induced DT-diaphorase activity in all strains examined, and the magnitude of induction varied depending on the strain and tissue. Among the 10 inbred strains tested, BALB/c and C57BL mice showed relatively large magnitudes of induction for liver DT-diaphorase, whereas C3H and CBA mice showed relatively small magnitudes. 3. Results of examinations of BALB/c-C3H-F1, -F2 and C57BL-CBA-F1 mice revealed that smaller magnitudes of induction of liver DT-diaphorase were inherited essentially as a dominant trait. The hereditary trait could be adequately explained by postulating two gene loci that regulate the magnitude of induction. 4. The possible significance of DT-diaphorase activity in chemical carcinogenesis was discussed.

Animals↗

PubMed1989

Rat strain variations in liver cytosolic DT-diaphorase activity and possible significance of the trait in carcinogenesis by azo dyes.

1. Strain variations among female rats in terms of cytosolic DT-diaphorase activity were studied in liver, heart and glandular stomach tissues with or without administration of 3-tert-butyl-4-hydroxyanisole (BHA). 2. BHA induced liver DT-diaphorase activity in all strains examined, and both the basal and induced activities varied according to strain. Among the five strains tested, Brown Norway (BN) and Sprague-Dawley (SD) rats showed relatively high levels of enzyme activity in the liver, whereas Fischer (F344) rats showed a relatively low level of activity. Results of examination of Fischer-BN-F1 rats indicated that a lower level of liver DT-diaphorase activity was inherited essentially as a dominant trait. 3. Liver DT-diaphorase activity in male rats was significantly lower than in female rats. Small strain variations of the activity, if any, were observed in the heart and stomach cytosolic fractions with or without induction by BHA. The magnitude of induction by BHA was also small, if any, in heart and stomach cytosolic fractions. 4. From these and other observations, we discussed the differences between rats and mice in these strain and tissue variations of DT-diaphorase activity, and also the possible significance of liver DT-diaphorase activity in carcinogenesis by azo dyes.

Alcohol Dehydrogenase↗