Search PubMed⌕ Search

Biomedical subjects

H Yoshimura

Publications and source records attributed to H Yoshimura.

At least 523 records · Page 29Linked to original sources
PubMed1984

Formation of novel nitrofuran metabolites in xanthine oxidase-catalyzed reduction of methyl 5-nitro-2-furoate.

After methyl 5-nitro-2-furoate was incubated with milk xanthine oxidase, three reduction products were isolated from the incubation mixture. Among them, two reduction products were new types of nitrofuran metabolites, i.e., metabolites 1 and 2 were identified as the dihydroxyhydrazine derivative (1,2-dihydroxy-1,2-di(5-methoxycarbonyl-2-furyl)hydrazine) and the hydroxylaminofuran derivative (methyl 5-hydroxylamino-2-furoate), respectively. Metabolite 3 was also identified as the aminofuran derivative (methyl 5-amino-2-furoate) by comparison with a synthetic sample.

Animals↗
PubMed1984

Isolation of a lipolytic factor (toxohormone-L) from ascites fluid of patients with hepatoma and its effect on feeding behavior.

The ascites fluids from patients with hepatoma or ovarian tumor and the pleural fluid from patients with malignant lymphoma elicited fatty acid release in slices of rat adipose tissue in vitro. The lipolytic factor, named toxohormone-L, was isolated from the ascites fluid of patients with hepatoma. The isolated preparation gave a single band on both disc gel electrophoresis and sodium dodecyl sulfate (SDS)-acrylamide gel electrophoresis in the presence of beta-mercaptoethanol. Its molecular weight was determined to be 70,000-75,000 and 65,200 by SDS-acrylamide gel electrophoresis and analytical ultracentrifugation respectively. Injection of toxohormone-L into the lateral ventricle of rats significantly suppressed food and water intakes. There was at least a 5-hr delay between its injection and the appearance of its suppressive effect.

Animals↗
PubMed1984

Clinico-pathological study of juvenile polyp of large intestine.

Although the difference of juvenile polyps between the childhood and adult groups was investigated, no significant difference could be pointed out both clinically and histologically. Since the polyps showing similar pathological findings were examined in the present investigation, it should be considered as a matter of course that no significant difference by age was pointed out. In a sense, these facts revealed the existence of a juvenile polyp which occurs in adult patients. In fact, the incidence of juvenile polyp which occurs in adult patients beyond the age of 20 has been estimated as 0 to 44% in the literature. If the term of juvenile polyp is not preferable in the adult cases, the term adult juvenile type polyp may be useful. Although several theories like as hamartoma, inflammation, allergy, etc. have been discussed for its histogenesis, it may be difficult to understand the histogenesis of juvenile polyps by a single theory.

Adolescent↗
PubMed1984

Clinico-pathological study of gastric cancers in the greater curvature.

The cases of gastric cancer in the greater curvature were 343 of 3,727, 9.2%, of which the early cancers were 62 of 1,060 cases or 5.9%. The average age of the patients with gastric cancer in this area was somewhat higher in comparison to that of all gastric cancers. In the early cancers of this area, the incidence of intestinal type cancers was rather frequent than that in the early cancers of the other areas. However, in the advanced cancers of this area, the incidence of diffuse type cancers was more frequent than that in the advanced cancers of the other areas. It should be considered that the difficulty of early diagnosis of cancer in the fundic gland area caused the discrepancy of the histological incidences of early and advanced cancers in the greater curvature. The incidence of early cancers with the size beyond 5 cm in diameter was 4.8% (15.5% in all early gastric cancers). Probably, the cancers in the greater curvature grow rapidly in comparison to those in the other areas.

Adenocarcinoma↗
PubMed1984

Difference in epoxides formation and their further metabolism between delta 9- and delta 8-tetrahydrocannabinols by human liver microsomes.

In vitro metabolism of delta 9- and delta 8-tetrahydrocannabinols (THCs) was studied using human liver microsomes. Delta 9- or delta 8-THC was incubated with microsomes in the presence of an NADPH-generating system. The metabolites formed were extracted with ethyl acetate, separated by preparative thin-layer chromatography, and identified as trimethylsilyl derivatives by gas chromatography-mass spectrometry. 9 alpha, 10 alpha-Epoxyhexahydrocannabinol (EHHC) together with four monohydroxylated metabolites was formed from delta 9-THC. The epoxide was found to resist the hydrolysis by epoxide hydrolase, and was further converted to several metabolites by monooxygenase system involving cytochrome P-450. On the other hand, 8 beta, 9 alpha-dihydroxyhexahydrocannabinol (diOH-HHC) instead of epoxy metabolites was formed from delta 8-THC under the conditions for monooxygenase. When 1,1,1-trichloropropene-2,3-oxide was further added to the incubation mixture, both of 8 alpha, 9 alpha-EHHCs were found to be formed from delta 8-THC. These epoxides of delta 8-THC were preferentially hydrolyzed to 8 beta, 9 alpha-diOH-HHC by epoxide hydrolase. These results indicate that 9 alpha, 10 alpha-EHHC formed from delta 9-THC is further metabolized not by epoxide hydrolase but by monooxygenase system involving cytochrome P-450, and that, on the contrary, 8 alpha, 9 alpha- and 8 beta, 9 beta-EHHCs derived from delta 8-THC may be metabolized by epoxide hydrolase rather than cytochrome P-450 in the human liver, forming 8 beta, 9 alpha-diOH-HHC.

Cytochrome P-450 Enzyme System↗
PubMed1984

High accumulation of 2,3,4,7,8-pentachlorodibenzofuran to hepatic microsomes of rats.

The tissue and subcellular distributions of 14C-2,3,4,7,8-pentachlorodibenzofuran (PenCDF), one of the most important causal agents of yusho, were studied using rats. More than 60% of the radioactivity given orally was accumulated in the liver after 5 d and this high percentage persisted over a period of 3 weeks. Subcellular fractionation of the liver homogenate showed unusual separation by PenCDF-pretreatment, but the distribution of radioactivity was just parallel to those of cytochrome P-450 content and glucose-6-phosphatase (EC3.1.3.9) activity. Gas chromatographic analysis provided evidence that the extracts from the liver and its subcellular fractionations contained only unchanged PenCDF. Those results strongly suggest that PenCDF has some affinity to endoplasmic reticulum of rat liver.

Animals↗
PubMed1984

Studies on cis-trans isomerization of nitrofuran derivatives by bacterial nitroreductases.

cis-trans Isomerization of 3-(5-nitro-2-furyl)-2-(2-furyl)-acrylamide(AF-2) using Escherichia coli B/r and its two 5-nitro-2-furaldehyde semicarbazone (nitrofurazone)-resistant mutants was investigated. The isomerizing activity was detected in all three strains and markedly increased with acquiring resistance to nitro-furazone in intact cells and cell free extracts. Two distinct isomerases, nicotinamide adenine dinucleotide phosphate(NADPH)-dependent one with high activity and NAD(P)H-dependent with low activity were separated by Sephadex G-100 and Sepharose 4B columns. Both enzyme activities agreed with the nitrofurazone-reducing activity due to O2-sensitive nitroreductase as reported previously. Another nitroreductase, O2-insensitive one, was unable to isomerize cis AF-2 to trans form. These results suggest that bacterial cis-trans isomerases are not O2-insensitive nitroreductase, but O2-sensitive ones.

Bacteria↗
PubMed1984

Metabolic disposition of 8 alpha, 9 alpha- and 8 beta, 9 beta-epoxyhexahydrocannabinols in the mouse.

Metabolic disposition of 8 alpha, 9 alpha- and 8 beta, 9 beta-epoxyhexahydrocannabinols (EHHCs) was studied using mice to clarify mechanisms which cause a difference in their pharmacological activities. At given time intervals from 0.5 to 60 min after intravenous injections of 8, 9-EHHCs (10 mg/kg), levels of unchanged epoxides extracted from blood, liver and brain of mice were determined by gas chromatography. Blood levels of both epoxides declined biphasically, and the concentrations of 8 alpha, 9 alpha-EHHC were higher than those of 8 beta, 9 beta-EHHC at all the time intervals determined. Biological half-lives in the slower phase were 17 and 13 min, respectively, for 8 alpha, 9 alpha-and 8 beta 9 beta-EHHCs. A similar result was obtained for 8,9-EHHCs concentrations in the liver. However, no significant difference in the brain levels was found between 8 alpha, 9 alpha-and 8 beta, 9 beta-EHHCs. Concentrations of 8 alpha, 9 beta-and 8 beta, 9 alpha-dihydroxyhexahydrocannabinols as well as unchanged epoxides 15 min after 8, 9-EHHCs injections increased significantly in the liver of mice pretreated with SKF 525-A (25 mg/kg, i.p.) comparing with the control. When delta 8-tetrahydrocannabinol (delta 8-THC), 8 alpha, 9 alpha- or 8 beta, 9 beta-EHHC was injected into mice intracerebroventricularly (25 micrograms/head), pentobarbital (40 mg/kg, i.p.)-induced sleep prolonging effect was ranked in the following order, 8 beta, 9 beta-EHHC greater than delta 8-THC greater than 8 alpha, 9 alpha-EHHC. These results suggest that monooxygenase system involving cytochrome P-450 and epoxide hydrolase together play important roles in the epoxides metabolism. In addition, different activities of 8 alpha, 9 alpha-and 8 beta, 9 beta-EHHCs to the central nervous system may cause a difference in their pharmacological effects rather than metabolic factors.

Animals↗
PubMed1984

Studies on N-demethylation of methamphetamine by liver microsomes of guinea-pigs and rats: the role of flavin-containing mono-oxygenase and cytochrome P-450 systems.

Relative participation of flavin-containing mono-oxygenase and cytochrome P-450 systems in N-hydroxylation of and formaldehyde release from methamphetamine were studied in vitro using liver microsomes of guinea-pigs and rats. In guinea pigs, only methimazole, an inhibitor of flavin-containing mono-oxygenase, significantly suppressed the above reactions. Formaldehyde release from methamphetamine was significantly inhibited not only by methimazole but also by inhibitors of the cytochrome P-450 system in liver microsomes from rats, but not guinea-pigs. Pretreatment of guinea-pigs with phenobarbital and 3-methylcholanthrene did not enhance the metabolism of methamphetamine. Pretreatment of rats with phenobarbital but not 3-methylcholanthrene increased slightly the N-demethylation of methamphetamine by liver microsomes. The results indicate that a marked species difference exists in the enzymes concerned with N-demethylation of methamphetamine. N-Oxidation predominates in guinea-pigs, whereas in rats, N-oxidation and C-oxidation of the methyl group participate equally as the initial reaction of the N-demethylation pathway.

Animals↗
PubMed1984

Polychlorinated biphenyls and dibenzofurans in patients with yusho and their toxicological significance: a review.

The rice oil ingested by the patients with yusho and their blood, liver, and adipose tissue were analyzed for individual congeners of polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs). The individual congeners identified were examined for accumulation in the liver of monkeys and rats, inducing activities of benzo[a]pyrene 3-hydroxylase, benzphetamine demethylase, and DT-diaphorase in rats, and gravimetric changes of the thymus and liver in rats. Among the six PCB congeners detected in yusho patients, 2,3,4,5,3',4'-hexa-CB seems to be the compound most related to yusho judging from its strong enzyme-inducing activities in the liver and the thymus atrophy and liver hypertrophy caused by feeding it to rats. PCDF congeners identified in the patients' tissues showed a stronger toxicity in rats than these PCBs, exhibiting stronger enzyme induction activities and gravimetric changes of the tissues. These PCDF congeners, especially 2,3,4,7,8-penta-CDF, were also very accumulative in the liver. Therefore, they are considered as the most important etiologic agents for the current symptoms and signs of yusho patients.

Adipose Tissue↗
PubMed1984

Polychlorinated biphenyls and dibenzofurans in patients with yusho and their toxicological significance: a review.

The rice oil ingested by the patients with yusho and their blood, liver, and adipose tissue were analyzed for individual congeners of polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans ( PCDFs ). The individual congeners identified were examined for accumulation in the liver of monkeys and rats, inducing activities of benzo[a]pyrene 3-hydroxylase, benzphetamine demethylase, and DT-diaphorase in rats, and gravimetric changes of the thymus and liver in rats. Among the six PCB congeners detected in yusho patients, 2,3,4,5,3',4'-hexa-CB seems to be the compound most related to yusho judging from its strong enzyme-inducing activities in the liver and the thymus atrophy and liver hypertrophy caused by feeding it to rats. PCDF congeners identified in the patients' tissues showed a stronger toxicity in rats than these PCBs, exhibiting stronger enzyme induction activities and gravimetric changes of the tissues. These PCDF congeners, especially 2,3,4,7,8-penta-CDF, were also very accumulative in the liver. Therefore, they are considered as the most important etiologic agents for the current symptoms and signs of yusho patients.

Adipose Tissue↗