Biomedical subjects

T Hirayama

Publications and source records attributed to T Hirayama.

At least 109 records · Page 6Linked to original sources

PubMed1998

Induction of fimbriated Vibrio cholerae O139.

Several fimbriated phases of Vibrio cholerae O139 strains were selectively induced and compared immunologically and biochemically with those of V. cholerae O1. Fimbrial antigens were detected on the surfaces of vibrio cells colonizing the epithelial cells of a rabbit small intestine. Convalescent-phase sera from six individuals infected with V. cholerae O139 revealed the development of antibody against the fimbrillin. These findings suggest that the fimbriae of V. cholerae O1 and O139 are expressed in vivo during infection and that consideration must be given to the use of fimbrial antigens as components of vaccines against cholera.

Animals↗

PubMed1998

Paroxysmal atrial fibrillation as a cause of potentially lethal ventricular arrhythmia with myocardial ischemia in hypertrophic cardiomyopathy--a case report.

The mechanism(s) of myocardial ischemia in hypertrophic cardiomyopathy remain unclear. In this report, the authors present a 75-year-old Japanese woman with nonobstructive hypertrophic cardiomyopathy in whom paroxysmal atrial fibrillation caused severe myocardial ischemia and induced sustained ventricular tachycardia. Her coronary angiogram showed normal findings, and no ischemic changes were provoked by either physical exercise testing or dobutamine stress echocardiography under sinus rhythm. In view of these findings, the rapid ventricular response in the absence of atrial contraction may aggravate or induce myocardial ischemia and predispose patients with hypertrophic cardiomyopathy to develop lethal ventricular arrhythmia.

Aged↗

PubMed1998

Active oxygens generation by flavonoids.

The hydrogen peroxide (H2O2)-generating effects of 14 flavonoids were investigated. Seven out of 14 flavonoids tested were found to generate H2O2 in an acetate buffer of pH 7.4. The H2O2-generating abilities of flavonoids decrease in the order of myricetin > baicalein > quercetin > (-)-epicatechin > (+)-catechin > fisetin = 7,8-dihydroxy flavone. This ability was observed in flavonoids with either a pyrogallol or catechol structure, and the pyrogallol-type flavonoids generated more H2O2 than the catechol-types. The amount of H2O2 generated by myricetin (pyrogallol-type flavonoid) was proportional to its concentration and to the reaction time until about 4 h. In addition, H2O2 generation by myricetin was dependent on the amount of dissolved oxygen in the buffer, and it was inhibited by the addition of superoxide dismutase. These results suggest that the flavonoids generate H2O2 by donating a hydrogen from their pyrogallol or catechol structure to oxygen, through a superoxide anion radical. It was also found that flavonoids which generated more H2O2 were more powerful antioxidants in the NADPH-dependent lipid peroxidation of rat microsomes.

Animals↗

PubMed1998

Mechanism of endothelium-dependent vasorelaxation evoked by lysophosphatidylcholine.

Vasorelaxation induced by lysophosphatidylcholine (LPC) and platelet activating factor (PAF) was examined in rings isolated from rat aorta and mesenteric artery. LPC caused dose-dependent vasodilatation, which was sensitive to CV-6209, a PAF antagonist, and NG-monomethyl-L-arginine, a nitric oxide synthase inhibitor, but insensitive to indomethacin. PAF (10(-7)M) caused a tachyphylactic effect in mesenteric artery, but no tachyphylactic effect was demonstrated with LPC. Vasorelaxation patterns with LPC differed from those with PAF in the rat mesenteric artery. These results suggest that LPC-induced vasorelaxation may involve increased nitric oxide production mediated by the PAF receptor pathway, another receptor pathway possibly blocked by CV-6209, or PAF itself produced in endothelial cells in response to LPC.

Animals↗

PubMed1998

Molecular genetic diagnosis of a family with hypercholesterolemia by a mismatched PCR-RFLP method for genotyping single base substitution of the LDL receptor gene.

Plasma lipid and lipoprotein levels reflect in part the influence of relevant genetic loci. Defects at some of these loci account for specific types of dyslipoproteinemia occurring with regularity among family members. In the course of familial investigations of coronary artery disease, we identified an family in which several members were affected with elevated low density lipoprotein (LDL) cholesterol levels. To study the genetic defects responsible for plasma lipoprotein abnormality in this pedigree, we developed a simple method for genotyping a single base substitution that does not affect a restriction recognition enzyme site in exon 10 of the LDL receptor gene. Using our mismatched PCR method, this G- > A substitution at nucleotide 1413 could be genotyped in the form of a biallelic restriction fragment length polymorphism (RFLP) after digestion with restriction enzyme Hpa II. Linkage analysis using this molecular method demonstrated that the defect at the LDL receptor locus is responsible for elevated LDL cholesterol phenotype observed in this family by segregation of defective alleles at the LDL receptor locus with the disease (peak decimal logarithm of odds score > 3.0).

Adolescent↗

PubMed1998

Familial hypercholesterolemia kindred in Utah with novel C54S mutations of the LDL receptor gene.

In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To determine the genetic etiology of the lipoprotein abnormalities, we screened DNA samples for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein (LDL) receptor gene. Novel point mutations were identified in the proband: a T-to-A transversion at nucleotide position 223, causing substitution of Ser for Cys at codon 54 in exon 3 of the receptor gene. This amino acid replacement would disrupt one of the disulfide bonds necessary for maintenance of the secondary structure of the repeat at the N-terminal of the receptor, prevent correct folding of the receptor, and result in defective intracellular transport of the receptor.

Adult↗

PubMed1998

Familial hypercholesterolemia with cholesteryl ester transfer protein deficiency.

A 21-year-old male was clinically diagnosed with familial hypercholesterolemia (FH) by the manifestations of hypercholesterolemia, tendon xanthoma and family history of premature coronary heart disease. Low density lipoprotein receptor gene was analyzed in attempt to determine a possible point mutation. The normal sequence was partially preserved, and the patient was genetically diagnosed as a heterozygote of FH. In addition, screening for two cholesteryl ester transfer protein (CETP) gene mutations common to Japanese revealed the patient to be a heterozygote of CETP deficiency. A complication of two influential mutations for atherosclerotic ailments was genetically ascertained.

Adult↗

PubMed1998

[Effect of bisoprolol, a beta 1-selective beta-blocker, on lipid and glucose metabolism and quality of life in elderly patients with essential hypertension].

The present study investigated the effect of bisoprolol, a beta 1-selective beta-blocker without intrinsic sympathomimetic activity (ISA), on lipid and glucose metabolism and quality of life (QOL) in elderly patients with essential hypertention. Bisoprolol at doses of 5-10 mg was administered once daily for 12 weeks to 60 non-elderly and 21 elderly outpatients with mild to moderate essential hypertension. In both groups bisoprolol significantly decreased both systolic and diastolic blood pressures and significantly reduced pulse rates to the same extent. The levels of serum cholesterol, HDL-cholesterol and triglyceride, and the response of plasma glucose and insulin to 75 g oral glucose load, were not changed in either group by the bisoprolol treatment. Bisoprolol significantly improved QOL in both groups. Bradycardia, a side effect attributable to bisoprolol, was noted in only one patient in the elderly group. These results suggest that bisoprolol is a safe and useful antihypertensive drug in elderly and non-elderly patients with essential hypertension.

Adrenergic beta-Antagonists↗

PubMed1998

A role of SH-compounds in maturation of melanosomes in cells cultured from nevus Ota.

A role of SH-compounds such as cysteine and glutathione in melanogenesis in dermal melanocytes cultured from Ota's nevus tissue was demonstrated in relation to another substrate, dihydroxyphenylalanine (DOPA). Chemical analysis of eumelanin and pheomelanin was performed in addition to the conventional electron microscopic observation. Supplements of the culture medium with each of these compounds separately for two weeks gave rise to the formation of pre-pheomelanosomes and secondary lysosomes or myelinosome-like inclusions. When DOPA and glutathione were added to the medium together, the maturation of melanosomes was promoted. This was proven by the increase in electron-density of pre-melanosomes observed as well as by the content of pheomelanin and eumelanin. However, mature melanosomes were not formed when each of these chemicals was added to the medium individually for the same periods. The melanosome maturation seemed to occur via a process involving secondary lysosomes or myelinosomes, in which more electron-dense particles accumulated in the presence of both reagents. The pheomelanosomal process was also observed, but typical eumelanosome-related processes were not observed in this culture system.

Cell Differentiation↗

PubMed1998

[Methods of evaluating SPECT images: the usefulness of the Matsuda's method by the Patlak plot method in children].

Single photon emission computed tomography (SPECT) is a tool to study cerebral blood flow (CBF) kinetics. There are three methods of evaluating SPECT images: visual, semi-quantitative (evaluation of the radioactivity ratio of the cerebral region to the cerebellum [R/CE] or to the thalamus [R/TH]) and quantitative (Matsuda's method by Patlak plot method using 99m Tc-hexamethylpropylene amine oxime radionuclide angiography). We evaluated SPECT images by the quantitative method in 14 patients with neurological disorders and examined the correlation of the results to those obtained by the semi-quantitative method. There was no significant correlation between the R/CE or R/TH ratio and regional CBF except two regions. The evaluation by the semi-quantitative method may have been inappropriate, probably because the cerebellar or thalamic blood flow was not constant in each case. Evaluation by the quantitative method, on the other hand, seemed to be useful not only for the comparison of CBF among normal subjects, but also in the demonstration of progressive changes of CBF in the same case. The Matsuda's method by the Patlak plot method is suitable for examination of children, since it dose not require aortic blood sampling.

Adolescent↗

PubMed1997

Comparison of the mutational specificity induced by environmental genotoxin nitrated polycyclic aromatic hydrocarbons in Salmonella typhimurium his genes.

Mutagenicity of 15 nitrated polycyclic aromatic hydrocarbons (nitro PAHs), which were detected in ambient air particles and/or combustion source emissions, were examined using a set of six Salmonella typhimurium tester strains (TA7001 to TA7006), and the mutational specificity was characterized by the comparison of the mutagenic potencies of nitro-PAHs in the tester strains. Each strain carries a unique missense mutation in the histidine operon and is reverted by only one specific base-substitution out of six possible changes. All nitro-PAHs tested were mutagenic in multiple strains, and were classified into four categories based on the strains predominantly reverted. 1-Nitropyrene (1-NPy), 2,7-dinitrofluoren-9-one and 1,3-, 1,6- and 1,8-dinitropyrene isomers exerted the highest mutagenicity in strain TA7005 (C.G-->A.T transversion) followed by strain TA7006 (C.G-->G.C transversion). 2- And 3-nitrofluoren-9-one isomers, 2-NPy and 2,7-dinitrophenanthrene were also markedly mutagenic in strain TA7005 but not in strain TA7006. For 2-, 3- and 9-nitrophenanthrene isomers, 2-nitrofluoranthene (2-NFT) and 4-NPy, TA7004 (G.C-->A.T transition) was the most responsive strain. 3-NFT was unique, showing the highest mutagenicity in strain TA7002 (T.A-->A.T transversion). All nitro-PAHs tested induced C.G-->A.T transversion, which is observed as the most frequent base-substitution mutation of p53 tumor suppressor gene in human lung cancer.

Environmental Pollutants↗

PubMed1997

Reinnervation of denervated muscle by transplantation of fetal spinal cord to transected sciatic nerve in the rat.

When motor neurons in the spinal cord are destroyed, regeneration of motor axons and muscle reinnervation cannot be expected. We attempted reinnervation of the denervated muscle, i.e. motor unit reconstruction, using transplantation of the fetal spinal cord to the peripheral nerve. The sciatic nerve of an adult rat was resected for 20 mm, and a cavity was prepared using an autologous femoral vein at the distal stump of the nerve. The fetal spinal cord was then transplanted into the venous cavity. After 3-6 months, no voluntary muscle contraction was observed due to the absence of communication with the central nervous system. However, reinnervation of the muscles via the sciatic nerve by the transplanted spinal neurons was demonstrated electrophysiologically and histochemically. This suggested that a motor unit can be reconstructed by fetal spinal cord transplantation even if the original motor neurons in the spinal cord are not available.

Animals↗

PubMed1997

Helicobacter pylori vacuolating cytotoxin binds to the 140-kDa protein in human gastric cancer cell lines, AZ-521 and AGS.

To investigatie a potential mechanism of how Helicobacter pylori establishes infection, we purified a lot of vacuolating toxin (VacA) from supernatant of H. pylori ATCC49503 (tox+ strain 60190). We used an antibody which was prepared by immunizing rabbits with a synthetic peptide consisting of 16 amino acids reflecting a portion (Glu69-Arg83) of amino acid sequence of Vac A. VacA caused vacuoles in human gastric cancer cell lines AZ-521 AGS, and monkey kidney cell line COS-7, but not human promyeloblastic cell line HL-60. By immunoprecipitation analysis using anti VacA antibody, a biotinylated cell surface protein of 140kDa (p140) was precipitated only when the lysates of VacA-susceptible cells were incubated with VacA but not with inactivated VacA, indicating the association of p140 with VacA.

Animals↗

PubMed1997

Characterization of filamentous phages of Vibrio cholerae O139 and O1.

We have analyzed our collection of Vibrio cholerae O139 strains to determine whether filamentous phages are produced in their culture supernatants, and whether any replicative form of DNA is detectable in cell lysates. Two types of filamentous phage, designated fs1 (6.4 kb) and fs2 (8.5 kb), were found in strains of Vibrio cholerae O139, fs1 was commonly produced from clinical isolates of Vibrio cholerae O1. Infectious particles (filamentous phages) were inducible by subculture, mitomycin C, and cultivation in a ligated ileal loop of a rabbit. Type 4 fimbriae of Vibrio cholerae O1 sensitive to D-glucose and D-mannose were suggested to be receptors for fs1 and fs2. The genome of fs1 was revealed to encode a potential new enterotoxin homologous to zonula occludens toxin. Clarification of the relation of type 4 fimbriae and these filamentous phages will provide a new understanding of the colonization of Vibrio-cholerae O1 and O139. Thus the presence of a new enterotoxin encoded by the genome of filamentous phage like fs1 may clarify the pathogenesis of cholera toxin negative clinical isolates of Vibrio cholerae O1 and non-O1. Our findings combined with the earlier report by Ehara et al. [Microbio. Immunol. 37 (1993) 679-688] suggest that type 4 fimbriae of Vibrio cholerae O1 are important for the development of an effective vaccine against cholera.

Animals↗

PubMed1997

Functional cloning of a cDNA encoding Mei2-like protein from Arabidopsis thaliana using a fission yeast pheromone receptor deficient mutant.

To isolate Arabidopsis cDNAs that encode signal transducers and components involved in the regulation of meiosis, a trans-complementation analysis was performed using a Schizosaccharomyces pombe meiosis-defective mutant in which the genes for pheromone receptors were disabled. One cDNA obtained in this screening encodes a polypeptide, named AML1, that shows significant similarity to S. pombe Mei2 protein and has three putative RNA-recognition motifs like as Mei2. Mei2 is involved in the regulation of meiosis in fission yeast. Northern blot analysis showed that the AML1 gene is expressed in each organ. The possible functions of AML1 are discussed.

Amino Acid Sequence↗

PubMed1997

The enhancing effect of anionic alpha-helical peptide on cationic peptide-mediating transfection systems.

A peptide consisting of 12 amino acids including 3 glutamic acids (LAEL-LAEL-LAEL; 4(3)E) underwent pH-dependent conformational change from random coil to alpha-helix when the pH was decreased from 7.4 to 5.0 in the presence of egg PC. This alpha-helical 4(3)E had higher membrane-perturbation activity at acidic conditions compared with neutral conditions. When 4(3)E was incorporated with plasmid DNA-cationic peptide complex that utilizes an endocytosis pathway for uptake into cultured cells, high transfection efficiency was observed, indicating that 4(3)E can enhance the transfection activity of cationic peptide. It is likely that 4(3)E in the multi-complex of the plasmid DNA and the cationic peptide effectively disrupts the endosomal membrane and increases the population of the complex which could transfer to cytosol. The small lysosome-disruptive peptide is very probably useful as the enhancer molecule for the gene transfer techniques mediated by the endocytosis pathway.

Amino Acid Sequence↗

PubMed1997

Binding of cationic alpha-helical peptides to plasmid DNA and their gene transfer abilities into cells.

Polycationic reagents such as cationic lipids and poly-L-lysine are widely used for gene transfer into cells in vitro and show promise as vectors for in vivo gene therapy applications as nonviral gene transfer techniques. We have developed a novel transfection method using cationic amphiphilic alpha-helical oligopeptides with repeated sequences. Oligopeptide has the advantages of being easily designed and modified because of its simple structure. In this study, we synthesized five kinds of peptides of which the total chain length and the width of the hydrophobic region were changed. The binding of the peptides to plasmid DNA was evaluated by agarose gel electrophoresis. It was found that the long and/or hydrophobic peptides can strongly bind to the DNA. The formation of large aggregates with a 0.5-5-microm diameter, which consisted of the long peptides and the DNA, was observed by electron microscopy. The transfection abilities of the peptides were determined by the expression of luciferase from its cDNA in COS-7 cells. The long peptides showed high transfection abilities. As a result, it could be said that the transfection ability of these peptides was parallel to their ability to form aggregates with DNA. Furthermore, the transfection ability was increased by the addition of chloroquine in the transfection procedure. This result indicated that the internalization of the peptide-DNA aggregates would be mediated by the endocytosis pathway.

Animals↗

PubMed1997

Metabolic activation of 2- and 3-nitrodibenzopyranone isomers and related compounds by rat liver S9 and the effect of S9 on the mutational specificity of nitrodibenzopyranones.

The effect of rat liver S9 on the mutagenicity of 10 nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) was evaluated with Salmonella typhimurium TA98NR using S9 from phenobarbital-, 3-methylcholanthrene (MC)-, beta-naphthoflavone- and polychlorobiphenyl-treated and untreated rats. 2-Nitrofluorene (2-NFI), 2-nitrofluoren-9-one (2-NFlone), 2-nitrocarbazole (2-NCz), 3-NCz, 2-nitrodibenzothiophene (2-NDBT), 2-nitro-6H-dibenzo[b,d]pyran-6-one (2-NDBP) and 3-NDBP were metabolically activated by one or more of the S9 fractions, and the highest enhancement of the mutagenic potency of nitro-PAHs was observed with 3-MC-induced S9. Only in the case of 3-NFlone was the mutagenicity in strain TA98NR decreased by the addition of S9, regardless of S9 induction. 2-NDBP was most efficiently activated among nitro-PAHs tested by all S9 fractions used. The cytosolic fraction of S9 accounted for more of the activation of 2-NDBP than the microsomal fraction. NADH and NADPH were the most effective electron donors on the activation of 2-NDBP by S9, 2-NDBP was also metabolically activated by NADH plus commercial preparations of xanthine oxidase. These activations of 2-NDBP were inhibited by allopurinol, indicating that cytosolic xanthine oxidase in rat liver S9 participates in the activation of 2-NDBP. The potency of 2- and 3-NDBP isomers as base-substitution mutagens was also enhanced by S9. In the presence of S9, both compounds showed the highest mutagenicity in strain TA7005 (C.G-->A.T) followed by strains TA7004 (G.C-->A.T), TA7006 (C.G-->G.C) and TA7002 (T.A-->A.T), and this mutation specificity was similar to that without S9, indicating that the mechanism of mutagenesis caused by NDBP isomers with S9 is similar to that without S9.

Animals↗