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Biomedical subjects

R Yamauchi

Publications and source records attributed to R Yamauchi.

At least 19 recordsLinked to original sources
PubMed2001

Structural features of arabinogalactan-proteins from the fruit of Lycium chinense Mill.

In addition to the other arabinogalactan-proteins (AGPs) (Cp-1-C and -D) already reported, two kinds of AGP (Cp-2-B and Hp-2-C) were obtained from the fruit of Lycium chinense Mill. The ratio of arabinose to galactose was approximately 1:1 in both samples, and the carbohydrate was linked O-glycosidically to serine in Cp-2-B, and to both serine and threonine residues of the protein in Hp-2-C. The weight-average molecular weight was 71,000 for Cp-2-B and 120,000 for Hp-2-C. Both samples also contained non-reducing terminal 3-O- and 4-O-substituted galacturonic acids. The ratio of 6-O-substituted galactose (linear part) and 3,6-di-O-substituted galactose (branching point) was almost unity in both samples, being obviously different from the case of Cp-1-C (predominant in the branching domain) and Cp-1-D (predominant in the linear domain). These results offer fresh insight into the grouping of the AGPs, based on the ratio of 6-O- and 3,6-di-O-substituted galactosyl residues.

Amino Acids↗
PubMed2001

Effects of omeprazole and pirenzepine on enterochromaffin-like cells and parietal cells in rat stomach.

PURPOSE: The purpose of this study was to investigate the mechanism of the regulation of histamine synthesis in enterochromaffin-like cells, chemically and structurally, by treatment with omeprazole and pirenzepine. METHODS: The ultrastructures of enterochromaffin-like cells and parietal cells were examined in rats treated with oral omeprazole (20 mg/kg) or intraperitoneal pirenzepine (1 mg/kg) administration. Serum gastrin concentrations, mRNA levels of H+-K+-ATPase and histidine decarboxylase, and the fundic concentrations of somatostatin and histamine were determined. RESULTS: Pirenzepine treatment suppressed omeprazole-induced increases in serum gastrin levels and mRNA levels of H+-K+-ATPase and histidine decarboxylase. Pirenzepine also decreased omeprazole-induced increases of histamine concentration in fundic mucosa. Pirenzepine elevated somatostatin mRNA level, previously decreased by omeprazole treatment, in fundic mucosa. In the cytoplasm of enterochromaffin-like cells, omeprazole markedly reduced the numbers of vesicles and granules, but significantly increased their diameters, whereas pirenzepine treatment changed neither of these features. The densities and diameters of both vesicles and granules produced by treatment with omeprazole and pirenzepine were between those produced by treatment with omeprazole alone and pirenzepine alone. CONCLUSIONS: Omeprazole-induced hypergastrinemia and pirenzepine-induced somatostatin synthesis play important roles not only in histamine synthesis but also in ultrastructural changes in enterochromaffin-like cells.

Animals↗
PubMed2001

Design, syntheses, and structure-activity relationships of indan derivatives as endothelin antagonists; new lead generation of non-peptidic antagonist from peptidic leads.

A new lead generation of non-peptidic ET(A) antagonists from two peptidic ET(A)-selective ones, BQ-123 and FR139317, was performed. Using computer assisted molecular modeling, a putative pharmacophore was constructed from the superposition of the reported three-dimensional structure of the cyclic peptide BQ-123 and a presumable beta-turn active conformation of the linear peptide FR139317 formed by an intramolecular hydrogen bond. According to this model, a new series of indan derivatives were designed and synthesized. Among these, 5-isobutyrylamino-6-(1-naphthylmethyloxy)-3-(2-thienyl)-1-indancarboxylic acid (1b) showed a moderate ET(A) antagonistic activity (IC50 = 28 microM).

Antihypertensive Agents↗
PubMed2001

Analysis of molecular species of glycolipids in fruit pastes of red bell pepper (Capsicum annuum L.) by high-performance liquid chromatography-mass spectrometry.

Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and glucocerebroside) from fruit pastes of red bell pepper were separated by silica gel column chromatography. The molecular species of each glycolipid were separated and characterized by reversed-phase high-performance liquid chromatography coupled with on-line mass spectrometry using atmospheric pressure chemical ionization. The molecular species of steryl glucoside were beta-sitosteryl and campesteryl glucosides, and those of the acylated steryl glucoside were their fatty acid esters. The dilinolenoyl species was predominant in monogalactosyldiacylglycerol in addition to small amounts of another five molecular species, whereas digalactosyldiacylglycerol consisted of seven molecular species varying in their degree of unsaturation. The glucocerebroside class contained at least seven molecular species, which were characterized by proton nuclear magnetic resonance spectroscopy.

Capsicum↗
PubMed2001

Association analyses between genetic polymorphisms of endothelial nitric oxide synthase gene and hypertension in Japanese: The Suita Study.

OBJECTIVES: Endothelium-derived nitric oxide plays a key role in the regulation of vascular tone. Recently, endothelial nitric oxide synthase (eNOS) gene polymorphisms were reported to be associated with hypertension or coronary spasm. We investigated the association between the eNOS gene polymorphisms and hypertension in a large population-based sample of 4055 Japanese. DESIGN AND METHODS: We investigated two polymorphisms of the eNOS gene, Glu298Asp polymorphism of exon 7 and T(-786)C polymorphism of the promoter region. The genotype distribution in hypertensive subjects was compared to that in the other subjects. The influence of the genotype on blood pressure values was analyzed in the subjects not taking hypertensive medication. The promoter activities of the eNOS gene with the (-786)T or (-786)C allele were measured by a luciferase reporter gene assay. RESULTS: There was significant linkage disequilibrium between the two polymorphisms (P < 0.0001). The genotype distribution of the Glu298Asp or T(-786)C polymorphism did not differ between the hypertensive and the other subjects. No significant differences in the blood pressure of subjects not taking hypertensive medication were observed among the three genotypes of Glu298Asp or T(-786)C polymorphisms. No significant differences in the promoter activity were observed between bovine endothelial cells transfected with the (-786)T and (-786)C alleles. CONCLUSIONS: Our data suggested that these polymorphisms of the eNOS gene are unlikely to be major factors in the susceptibility to hypertension in the Japanese population studied.

Adult↗
PubMed2000

Bioactive peptides derived from food proteins preventing lifestyle-related diseases.

Many kinds of bioactive peptides which might prevent lifestyle-related diseases are released from food proteins after enzymatic digestion. Inhibitory peptides for angiotensin I-converting enzyme (ACE) having anti-hypertensive effect have been isolated from enzymatic digests of various food proteins. LKPNM, which was isolated from the thermolysin digest of dried bonito was activated 8-fold by ACE itself and showed a prolonged effect after oral administration. Two vasorelaxing peptides, ovokinin and ovokinin(2-7), showing antihypertensive effect after oral administration were obtained from ovalbumin digests. We found that low molecular weight peptides derived from food proteins lowered serum cholesterol without increasing excretion of cholesterol and bile acids. An immunostimulating peptide isolated from an enzymatic digest of soybean protein prevented alopecia induced by cancer chemotherapy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Analysis of the addition products of alpha-tocopherol with phosphatidylcholine-peroxyl radicals by high-performance liquid chromatography with chemiluminescent detection.

A chemiluminescence-based high-performance liquid chromatographic method was developed for the analysis of the addition products of alpha-tocopherol with phosphatidylcholine-peroxyl radicals (TOO-PC). The TOO-PC eluted from a reversed-phase column was reacted with a chemiluminescent reagent consisting of a Cypridina luciferin analog and a lipid-soluble iron chelate in acidic methanol at 50 degrees C, and the generated chemiluminescence was monitored. The detection limit for TOO-PC by this method was about 1 pmol. This method was applied to the detection of TOO-PC in the peroxidized membranes prepared from rabbit erythrocyte ghosts. When the erythrocyte ghosts were peroxidized by the addition of a water-soluble free radical initiator, a peak corresponding to TOO-PC was detected on the chromatogram with chemiluminescent detection. The amount of TOO-PC in the erythrocyte membranes increased with the depletion of endogenous alpha-tocopherol. The results indicate that this method proved useful for the detection of the TOO-PC formed by the peroxyl-radical scavenging reactions of alpha-tocopherol in biological systems.

Animals↗
PubMed1999

Synthesis of 5-hydroxy-2-(beta-D-ribofuranosyl)pyran-4-one from a pyranulose glycoside.

The synthesis of 5-hydroxy-2-(beta-D-ribofuranosyl)pyran-4-one (9) is described. Treatment of pyranulose glycoside with bromine in carbon tetrachloride afforded brompyranulose glycoside in 90% yield. The reaction of (6S)- and (6R)-4-bromo-6-hydroxy-6-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-6H- pyran-3-one (2) in acidic media was examined with the following results: the reaction of 2 with trifluoroacetic acid (TFA) in dioxane afforded a mixture of 5-hydroxy-2-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)pyran-4-one (3) and its furan derivative 5-hydroxy-2-{5-(benzoyloxy)methyl]furan-2-yl}pyran-4-one (4), but the use of hydrochloric acid formed the bromofurfural, 3-bromo-5-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-2-furancarboxyal dehyde only. Acetylation of a mixture (3 and 4) with acetic anhydride facilitated product separation to give the corresponding acetates 5-acetoxy-2-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)pyran-4-one (5) and 5-acetoxy-2-{5-[(benzoyloxy)methyl]furan-2-yl}pyran-4-one (6). Treatment of 5 with hydrazine afforded 3-hydroxymethyl-6-(beta-D-ribofuranosyl)-1H-pyridazin-4-one in 43% yield. Debenzoylation of 5 with aq ammonia gave 9 in 50% yield.

Anti-Bacterial Agents↗
PubMed1998

Antioxidant activity of a novel vitamin E derivative, 2-(alpha-D glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol.

A novel vitamin E derivative, 2-(alpha-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), has excellent water-solubility (> 1 x 10[3] mg/ml). The antioxidant activity of TMG was investigated. Kinetic studies of the inhibition of radical-chain reaction of methyl linoleate in solution demonstrated that the peroxyl radical-scavenging activity was not changed by the replacement of phytiyl side chain of vitamin E to glucosyl group. TMG acted as an effective inhibitor on lipid peroxidation of egg yolk phosphatidylcholine (PC)-liposomal suspension induced by a water-soluble and a lipid-soluble radical generator, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) and 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). Its effectiveness was higher than that of ascorbic acid (AsA) when liposomal suspension was exposed to a lipid-soluble radical generator, AMVN. TMG also showed an excellent antioxidant activity on cupric ion-induced lipid peroxidation of PC-liposomal suspension, and suppressed the oxidation of rat brain homogenate which contained trace level of iron ion. On the other hand, AsA acted as a prooxidant on both the cupric ion-induced liposomal peroxidation and the oxidation of rat brain homogenate. When human plasma was exposed to either AAPH or AMVN, the accumulation of cholesteryl ester hydroperoxides was retarded by the addition of TMG.

Adult↗
PubMed1998

Reaction of alpha-tocopherol in heated bulk phase in the presence of methyl linoleate (13S)-hydroperoxide or methyl linoleate.

alpha-Tocopherol and methyl (9Z,11E)-(S)-13-hydroperoxy-9,11-octadecadienoate (13-MeLOOH) were allowed to stand at 100 degrees C in bulk phase. The products were isolated and identified as methyl 13-hydroxyoctadecadienoate (1), stereoisomers of methyl 9,11,13-octadecatrienoate (2), methyl 13-oxo-9,11-octadecadienoate (3), epoxy dimers of methyl linoleate with an ether bond (4), a mixture of methyl (E)-12,13-epoxy-9-(alpha-tocopheroxy)-10-octadecenoates and methyl (E)-12,13-epoxy-11-(alpha-tocopheroxy)-9-octadecenoates (5), a mixture of methyl 9-(alpha-tocopheroxy)-10,12-octadecadienoates and methyl 13-(alpha-tocopheroxy)-9,11-octadecadienoates (6), alpha-tocopherol spirodiene dimer (7), and alpha-tocopherol trimer (8). alpha-Tocopherol and 13-MeLOOH were dissolved in methyl myristate, and the thermal decomposition rate and the distributions of reaction products formed from alpha-tocopherol and 13-MeLOOH were analyzed. alpha-Tocopherol disappeared during the first 20 min, and the main products of alpha-tocopherol were 5 and 6 with the accumulation of 1-4 which were the products of 13-MeLOOH. The results indicate that the alkyl and alkoxyl radicals from the thermal decomposition of 13-MeLOOH could be trapped by alpha-tocopherol to produce 5 and 6. The reaction products of alpha-tocopherol during the thermal oxidation of methyl linoleate were compounds 6 and 7. Since the radical flux during the autoxidation might be low, the excess alpha-tocopheroxyl radical reacted with each other to form 7.

Chromatography, High Pressure Liquid↗
PubMed1998

Cloning of hamster preproendothelin-1 cDNA and its expression in the heart.

To elucidate the pathophysiologic roles of endothelin-1 (ET-1) in the heart, we first cloned and sequenced a part of hamster preproET-1 cDNA from the heart of the CHF146 hamsters. The amino acid sequence has 89% homology to that of rat preproET-1 in the cloned part. The deduced hamster 21-residue mature ET-1 is identical to human, rat, canine, and mouse ET-1. In the next step we investigated the expression of preproET-1 mRNA in the failing heart of CHF146 hamsters. For this purpose, we used 46-week-old CHF146 hamsters and age-matched control healthy hamsters. Left ventricular (LV) + dP/dtmax was significantly lower in CHF146 hamsters than in control hamsters. LV end-diastolic pressure was significantly higher in CHF146 hamsters than in control hamsters, as was central venous pressure. These results suggested that the CHF146 hamsters developed congestive heart failure. The expression of preproET-1 mRNA was greatly enhanced in the LV of the CHF146 hamsters. Because it has been reported that ET-1 induces cardiac hypertrophy and injury to cardiac myocytes in addition to its potent positive inotropic and chronotropic actions, the present findings suggest that endogenous ET-1 plays pathophysiologic roles in the failing heart of CHF146 hamsters.

Amino Acid Sequence↗
PubMed1998

Preparation and characterization of 8a-(phosphatidylcholine-dioxy)-alpha-tocopherones and their formation during the peroxidation of phosphatidylcholine in liposomes.

alpha-Tocopherol was reacted with the phosphatidylcholines (PCs), 1-palmitoyl-2-linoleoyl-3-sn-PC (PLPC), 1-palmitoyl-2-linolenoyl-3-sn-PC, 1-palmitoyl-2-arachidonoyl-3-sn-PC (PAPC) and 1-stearoyl-2-arachidonoyl-3-sn-PC, in the presence of the free radical initiator, 2,2'-azobis (2,4-dimethylvaleronitrile), at 37 degrees C. The addition products of alpha-tocopherol with the PC peroxyl radicals were isolated and identified as 8a-(PC-dioxy)-alpha-tocopherones, in which the peroxyl radicals derived from each PC molecule attacked the 8a-position of the alpha-tocopheroxyl radical. The antioxidative efficiency of alpha-tocopherol against the peroxidation of PLPC and PAPC in liposomes was assessed by the formation of the reaction products of alpha-tocopherol. When alpha-tocopherol was oxidized in the presence of the water-soluble free radical initiator, 2,2'-azobis (2-amidinopropane) dihydrochloride, epoxy-alpha-tocopherylquinones were mainly produced together with 8a-(PC-dioxy)-alpha-tocopherones and alpha-tocopherylquinone. The yield of alpha-tocopherylquinone was increased by treating each sample with dilute acid which indicates the presence of tocopherone precursors other than the 8a-(PC-dioxy)-alpha-tocopherones. The same products were also detected from iron-dependent peroxidation, although the yields were very low.

Amidines↗
PubMed1998

Pharmacological profile of T-0201, a highly potent and orally active endothelin receptor antagonist.

The authors studied the pharmacological properties of N-(6-(2-(5-bromopyrimidin-4-yl)-4-(2-hydroxy-1, 1-dimethylethyl)benzensulfonamide sodium salt sesquihydrate (T-0201), a new nonpeptide endothelin (ET) receptor antagonist, in vitro and in vivo. In binding studies, T-0201 competitively antagonized the specific binding of [125I]-ET-1 to human cloned ETA receptors (the Ki value was 0.015 +/- 0.004 nM). T-0201 weakly inhibited [125I]-ET-1-binding to human cloned ETB receptors; the Ki value was 41 +/- 21 nM. T-0201 shifted the concentration-response curve of ET-1-induced contraction of the isolated rat aorta (ETA receptors) to the right (pA2 = 9.0 +/- 0.2). In the isolated rat trachea, a selective ETB agonist sarafotoxin S6c-induced contraction was inhibited by T-0201 (pA2 = 6.8 +/- 0.3). T-0201 also caused the inhibition of ET-1-induced contraction of the isolated rabbit pulmonary artery (pA2 = 5.7 +/- 0.3). In anesthetized rats, T-0201 (0.01-1 mg/kg) inhibited the pressor response to exogenous big ET-1 (1 nmol/kg i.v.), after both i.v. and p.o. administration, in a dose-dependent manner. The significant inhibitory effect of orally administered T-0201 on big ET-1-induced pressor response lasted for 4 hr at 0.1 mg/kg and for 8 hr at 1 mg/kg. Thus the present study demonstrates that T-0201 is a highly potent, long-lasting, orally active and selective ETA receptor antagonist.

Animals↗
PubMed1997

Synthesis of a novel vitamin E derivative, 2-(alpha-D-glucopyranosyl) methyl-2,5,7,8-tetramethylchroman-6-ol, by alpha-glucosidase-catalyzed transglycosylation.

A novel derivative of vitamin E, vitamin E glucoside, was synthesized from 2-hydroxymethyl-2,5,7,8-tetramethylchroman-6-ol and maltose in a solution containing DMSO by transglycosylation with alpha-glucosidase from Saccharomyces species. The glycosylated product was identified as 2-(alpha-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG) by mass spectrometry and nuclear magnetic resonance spectroscopy. The optimal pH of transglycosylation was 5.5, and the yield of TMG increased as the concentration of maltose increased. TMG has high solubility in water (> 1 x 10(3) mg/mL). The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of TMG was found to be nearly the same as those of alpha-tocopherol, Trolox (2-carboxy-2,5,7,8-tetramethylchroman-6-ol), and ascorbic acid.

Antioxidants↗
PubMed1997

Fixed drug eruption caused by iopamidol, a contrast medium.

We report a patient who developed a fixed drug eruption caused by the contrast medium, Iopamidol. We diagnosed it by her episode pattern and the results of patch tests. This substance has not been previously implicated as a cause of fixed drug eruption. Immunohistochemical studies showed Fas expression in keratinocytes of the lesion, but not in the uninvolved skin. This finding may explain the preferential localization of fixed drug eruption.

Adult↗
PubMed1996

Oxidation of alpha-tocopherol during the peroxidation of dilinoleoylphosphatidylcholine in liposomes.

Liposomal suspensions of dilinoleoylphosphatidylcholine (DLPC) containing alpha-tocopherol (0.1 mol%, based on DLPC were oxidized at 37 degrees C. The oxidation was initiated by a lipid-soluble or water-soluble free radical initiator, or by the addition of CuSO4 and fructose. In all the oxidation systems, alpha-tocopherol suppressed the formation of DLPC hydroperoxides until all the alpha-tocopherol had been depleted. The oxidation products of alpha-tocopherol were 8a-alkyldioxy-alpha-tocopherones, 5,6-epoxy-alpha-tocopherylquinone, 2,3-epoxy-alpha-tocopherylquinone, and alpha-tocopherylquinone. The 8a-alkyldioxy-alpha-tocopherones were decomposed in the liposomes primarily by being hydrolyzed to produce alpha-tocopherylquinone. The results indicate that alpha-tocopherol can trap peroxyl radical to form 8a-alkyldioxy-alpha-tocopherones which are hydrolyzed to alpha-tocopherylquinone in phospholipid bilayers. In another oxidation pathway, alpha-tocopherol may be oxidized by peroxyl radicals to form isomeric epoxy-alpha-tocopherylquinones.

Amidines↗
PubMed1995

Structure of an exocellular polysaccharide of Lactobacillus helveticus TN-4, a spontaneous mutant strain of Lactobacillus helveticus TY1-2.

Lactobacillus helveticus strain TN-4, a spontaneous mutant strain of Lactobacillus helveticus TY1-2, produced an exocellular polysaccharide from reconstituted skim milk. On the basis of the results of methylation analysis, enzymatic digestion, mild Smith degradation, mild acid hydrolysis, acetolysis, and 1D and 2D 1H-NMR spectroscopy, it was concluded that the polysaccharide has a D-galactofuranose containing hexasaccharide repeating unit with the following structure: [formula see text]

Animals↗