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Biomedical subjects

H Yoshimura

Publications and source records attributed to H Yoshimura.

At least 613 records · Page 34Linked to original sources
PubMed1981

Studies on oxygen-insensitive nitrofuran reductase in Escherichia coli B/r.

Oxygen-insensitive nitrofuran reductase in Escherichia coli B/r was clearly resolved by DEAE-cellulose column chromatography into two components, one NADPH-linked, and the other both NADPH- and NADH-linked. It is known that the strain requires resistance to nitrofurazone in two mutational steps. It is known that the the first step mutants had no NADPH-linked component and the second step ones had neither this component nor the NAD(P)-H-linked one. The NADPH- and NADH-linked activities of the latter component were similarly inactivated by heat or urea treatment. In addition, it was found that these activities were significantly inhibited by dicoumarol, an NAD(P)H dehydrogenase inhibitor, to similar extents. These results suggest that the activities of the NAD(P)H-linked component originate from a single enzyme. On the other hand, the NADPH-linked component was less sensitive to heat, urea and dicoumarol.

Cell-Free System↗
PubMed1981

Clinic-pathological study of gastro-duodenal ulcers from the standpoint of aging of the patients.

The gastric ulcer and duodenal ulcer resected surgically were investigated clinico-pathologically. The duodenal ulcers occurred frequently in the third to fourth decades in the patients with relatively normal gastric mucosal structure and high acid secretion. On the other hand, the gastric ulcer occurred frequently in the fifth to sixth decades in the patients with moderate to marked mucosal damage and subsequent intestinal metaplasia. Although the duodenal ulcers occurred frequently in the anterior wall, the gastric ulcers were usually found in the lesser curvature and posterior wall. Multiple lesions in the patients of gastric ulcer and linear lesion in the patients of duodenal ulcer increase by aging. The duodenal ulcers were found at the rate of 25% in the patients with gastric ulcer and the gastric ulcers were found at the rate of 40% in the patients with duodenal ulcer.

Adolescent↗
PubMed1981

Delayed-type hypersensitivity as revealed on the footpads of mice to azobenzenearsonate-acetyl bovine serum albumin.

A strong delayed-type footpad reaction was established in mice using azobenzenearsonate-acetyl bovine serum albumin (ABA-AcBSA) as an antigen. Male ddY/S mice were sensitized by subcutaneous injection of 100 microliter of Freund's complete adjuvant - saline (1:1) emulsion containing 100 microgram of the antigen and challenged by subcutaneous injection of 2.5 microliter of Freund's incomplete adjuvant - saline (1:1) emulsion with 2.5 microgram antigen in the footpad on the 10th day after the sensitization. The analysis of the system which fulfilled criteria for delayed-type hypersensitivity with regard to kinetics, passive transfer and histology of the footpad reaction, and the effect of dexamethasone, indomethacin and quinacrine on the footpad reaction were described.

Animals↗
PubMed1981

Hemodynamic determinants of pulmonary valve motion during systole in experimental pulmonary hypertension.

To clarify the determinants of pulmonary valve (PV) motion in pulmonary hypertension, we examined the correlations among PV echo patterns, the pulmonary artery (PA) flow curve just above the PA orifice and the pulmonary artery-right ventricle (PA-RV) pressure gradient. By constricting the PA, we could produce a variety of PV echo patterns, including midsystolic semiclosure in open-chest dogs. Throughout the experiments, the PV echo pattern and PA flow curve were similar in pattern and timing. When the PV echo showed midsystolic semiclosure with reopening. The PA flow curve showed a transient decrease followed by a transient increase during midsystole. The PA-RV pressure gradient became transiently positive (PA pressure greater than RV pressure) and then negative in midsystole only when the PV echo showed midsystolic semiclosure with reopening. In conclusion, PV motion during systole may be instantaneously determined by PA flow change and the PA-RV pressure gradient during the cardiac cycle in experimental pulmonary hypertension.

Animals↗
PubMed1981

Mode of reactions between xanthine oxidase and aromatic nitro compounds.

The electron transfer mechanism in the reduction of aromatic nitro compounds by xanthine oxidase was investigated using methyl p-nitrobenzoate and p-nitroacetophenone as substrates. Methyl p-nitrobenzene was reduced by both one-electron and more than two-electron transfer mechanisms in the enzyme-electron donor system. When NADH was used as an electron donor, the ratio of one-electron flux to the total electron flux (the summation of one-electron and more than two-electron fluxes) was dependent on pH of the medium, but not on the concentration of the nitro compounds. The reverse was the case when the electron donor was xanthine. Additional experiments showed that methyl p-nitrobenzoate or p-nitroacetophenone was reduced to the corresponding hydroxylamino compounds and amino compounds by xanthine oxidase supplemented with xanthine or NADH. In these cases, the pattern of formation of the reduction products was dependent on the enzyme activity. The present study strongly suggested that the reduction of aromatic nitro compounds by xanthine oxidase proceeds through the four-electron and six-electron transfer mechanisms as well as the one-electron transfer mechanism.

Acetophenones↗
PubMed1981

Further studies of sulfoxide-reducing enzyme system.

Various kinds of flavoenzymes such as NADPH-cytochrome c reductase, NADH-cytochrome b5 reductase, xanthine oxidase, lipoamide dehydrogenase and NADH dehydrogenase supplemented with their electron donors exhibited the sulfoxide reductase activity in the presence of a partially purified soluble factor from guinea pig liver. The present study suggests that new electron transfer systems in which the soluble factor functions as an electron carrier coupled with flavoenzymes described above are responsible for the sulfoxide reduction.

Animals↗
PubMed1981

In vitro and in vivo interactions of delta 8-tetra-hydrocannabinol and its metabolites with hepatic microsomal drug metabolizing enzyme systems of mice.

Interactions of delta 8-tetrahydrocannabinol (delta 8-THC) and its metabolites, 11-hydroxy-delta 8-THC, 11-oxo-delta 8-THC and delta 8-THC-11-oic acid, with hepatic microsomal drug metabolizing enzyme were studied in vitro and in vivo using mice. All the cannabinoids used were shown to produce a type I spectral change of cytochrome P-450 in hepatic microsomes. THe apparent binding affinities (Ks) for delta 8-THC, 11-hydroxy-delta 8-THC, 11-oxo-delta 8-THC and delta 8-THC-11-oic acid were 5.2, 169.6, 33.2 and 148.8 microM, respectively. delta 8-THC, 11-oxo-delta 8-THC and delta 8-THC-11-oic acid (100 microM) caused a significant stimulation of NADPH oxidation in vitro with microsomes. In addition, delta 8-THC (20, 40 and 80 microM) markedly inhibited p-nitroanisole O-demethylase and aniline hydroxylase in microsomes. 11-Hydroxy-delta 8-THC and 11-oxo-delta 8-THC also showed the inhibitory effect, but to lesser extents. Furthermore, single pretreatments with delta 8-THC and 11-oxo-delta 8-THC (30 mg/kg, i.v.) significantly decreased activities of p-nitroanisole O-demethylase and aniline hydroxylase in hepatic microsomes, accompanying a decrease of cytochrome P-450 content in case of delta 8-THC. On the other hand, all these pretreatments except for that with delta 8-THC-11-oic acid showed a stimulatory effect on p-nitrophenol glucuronidation with hepatic microsomes, in contrast to an inhibitory effect in vitro.

Aniline Hydroxylase↗
PubMed1981

Direct flowmetry of the mitral valve. A simple approach in the experimental study.

A flow probe for direct measurement of blood flow of the mitral valve was devised. It was useful for acute experiment, particularly concerning pathophysiology of the mitral valve function. Insertion of the probe into the left atrium and fixation to the left atrial wall and thus to the mitral orifice were readily and satisfactorily performed without disturbance of blood flow and valvular function. It must also be emphasized that support with cardiopulmonary bypass was not necessary at the time of insertion of the probe. Effectiveness of the procedure has been confirmed through simultaneous observation of echocardiogram and mitral blood flow of the dog's heart with ruptured chordae tendineae.

Animals↗
PubMed1981

Behavioral characteristics of scent marking behavior in the Mongolian gerbil (Meriones unguiculatus).

Behavioral characteristics of scent marking behavior in the Mongolian gerbil were investigated using the open-field apparatus. The gerbils raised in Japan exhibited a similar behavioral topography of scent marking behavior to those observed in the United States. The incidence and frequency of marking behavior were sexually dimorphic with predominance in males. A midventral sebaceous gland of the male was also larger than that of the female. In male gerbils which has been housed with other males (4 animals per cage), the frequency of marking was differed individually among the cage mates. On the other hand, when two males having similar marking frequency were housed in pairs for one month, one of the two increased the marking frequency compared with the prepairing whereas the other decreased it significantly. The evidence tends to support the notion that scent marking behavior is a species-common response in gerbils and that the behavior correlate to dominance and social ranking.

Animals↗
PubMed1981

Metabolic fate of noscapine. III. Further studies on identification and determination of the metabolites.

1. From the urine of rats, rabbits and humans treated with noscapine, two novel metabolites were isolated and identified as 7-hydroxy-6-methoxyphthalide (MA-1) and 6-hydroxy-7-methoxyphthalide (MA-2), mainly by mass spectrometry. 2. MA-2 (free and conjugated) amounted to 8.5% dose in rats (n=2) and 1.7% dose in rabbits (n=2) during the first 48 h. In humans, MA-2 was excreted in amounts of 6.0 to 10.3% dose in the first 24 h urine (three men and a woman), although one woman excreted 52.5% dose as MA-2 during the same period. In all three species MA-2 was excreted 10 times more as conjugates than as the free metabolite. MA-1 was excreted only in trace amounts in the urines of three species. 3. In rabbits, the drug was metabolized also to 1-alpha-methyl-8-methoxy-6,7-dihydroxy-1-(6,7-dimethoxy-3-phthalidyl)-1,2,3,4-tetrahydroisoquinoline (4.6% dose, conjugated only) using g.l.c.-mass spectrometry. This metabolite was excreted conjugated at 0.6 to 5.2% dose in five human subjects, but was not detected in rats. 4. Three 0-demethylated metabolites of noscapine, previously reported, were determined using g.l.c.-mass spectrometry. The total demethylated metabolites (free and conjugated) amounted to 0.2%, 4.0% and 0.1-1.5% dose, respectively, in rats, rabbits and humans (n=5) in the first 24 h urine.

Adult↗