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Biomedical subjects

T Hirayama

Publications and source records attributed to T Hirayama.

At least 91 records · Page 5Linked to original sources
PubMed1999

Characterization of the YbBa2Cu3O7-y and YBa2Cu3O7-y thin superconducting films prepared by chemical solution deposition on MgO(001) substrate.

Thin superconducting films of the YbBa2Cu3O7-y (Yb123) and YBa2Cu3O7-y (Y123), prepared by post-deposition annealing of the metal naphthenates gels spin-coated on MgO(001) substrate, have been characterized by cross-sectional high-resolution electron microscopy and X-ray diffraction. It was found that the c-axis Yb123 films were epitaxially grown on the MgO(001) substrate at the temperature range from 700 degrees C to 775 degrees C in a gas mixture containing Ar and O2 with the oxygen partial pressure of p(O2) = 10(-4) atm. In contrast to the Yb123 films, it was found that Y123 films could be derived at a wider temperature range from 750 degrees C to 950 degrees C. Randomly oriented Y123 films were also grown on the MgO(001) substrate besides the majority of in-plane c-axis oriented growth.

Barium↗
PubMed1999

A transmembrane hybrid-type histidine kinase in Arabidopsis functions as an osmosensor.

Water deficit and the resulting osmotic stress affect plant growth. To understand how plant cells monitor and respond to osmotic change from water stress, we isolated a cDNA from dehydrated Arabidopsis plants. This cDNA encodes a novel hybrid-type histidine kinase, ATHK1. Restriction fragment length polymorphism mapping showed that the ATHK1 gene is on chromosome 2. The predicted ATHK1 protein has two putative transmembrane regions in the N-terminal half and has structural similarity to the yeast osmosensor synthetic lethal of N-end rule 1 (SLN1). The ATHK1 transcript was more abundant in roots than other tissues under normal growth conditions and accumulated under conditions of high or low osmolarity. Histochemical analysis of beta-glucuronidase activities driven by the ATHK1 promoter further indicates that the ATHK1 gene is transcriptionally upregulated in response to changes in external osmolarity. Overexpression of the ATHK1 cDNA suppressed the lethality of the temperature-sensitive osmosensing-defective yeast mutant sln1-ts. By contrast, ATHK1 cDNAs in which conserved His or Asp residues had been substituted failed to complement the sln1-ts mutant, indicating that ATHK1 functions as a histidine kinase. Introduction of the ATHK1 cDNA into the yeast double mutant sln1Delta sho1Delta, which lacks two osmosensors, suppressed lethality in high-salinity media and activated the high-osmolarity glycerol response 1 (HOG1) mitogen-activated protein kinase (MAPK). These results imply that ATHK1 functions as an osmosensor and transmits the stress signal to a downstream MAPK cascade.

Amino Acid Sequence↗
PubMed1999

Nitrite reductase from Pseudomonas aeruginosa released by antimicrobial agents and complement induces interleukin-8 production in bronchial epithelial cells.

We have recently reported that nitrite reductase, a bifunctional enzyme located in the periplasmic space of Pseudomonas aeruginosa, could induce interleukin-8 (IL-8) generation in a variety of respiratory cells, including bronchial epithelial cells (K. Oishi et al. Infect. Immun. 65:2648-2655, 1997). In this report, we examined the mode of nitrite reductase (PNR) release from a serum-sensitive strain of live P. aeruginosa cells during in vitro treatment with four different antimicrobial agents or human complement. Bacterial killing of P. aeruginosa by antimicrobial agents induced PNR release and mediated IL-8 production in human bronchial epithelial (BET-1A) cells. Among these agents, imipenem demonstrated rapid killing of P. aeruginosa as well as rapid release of PNR and resulted in the highest IL-8 production. Complement-mediated killing of P. aeruginosa was also associated with PNR release and enhanced IL-8 production. The immunoprecipitates of the aliquots of bacterial culture containing imipenem or complement with anti-PNR immunoglobulin G (IgG) induced twofold-higher IL-8 production than did the immunoprecipitates of the aliquots of bacterial culture with a control IgG. These pieces of evidence confirmed that PNR released in the aliquots of bacterial culture was responsible for IL-8 production in the BET-1A cells. Furthermore, the culture supernatants of the BET-1A cells stimulated with aliquots of bacterial culture containing antimicrobial agents or complement similarly mediated neutrophil migration in vitro. These data support the possibility that a potent inducer of IL-8, PNR, could be released from P. aeruginosa after exposure to antimicrobial agents or complement and contributes to neutrophil migration in the airways during bronchopulmonary infections with P. aeruginosa.

Anti-Bacterial Agents↗
PubMed1999

Quantification of two aromatic amine mutagens, PBTA-1 and PBTA-2, in the yodo river system.

The levels of two aromatic amine mutagens, 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5-a mino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), were quantitatively analyzed in the Yodo River system in Japan. The river water samples were collected at nine sampling sites from the Yodo River system twice or three times between May and July in 1997. PBTA-1 and PBTA-2 in the river water samples were concentrated on blue rayon columns, partially purified by high-performance liquid chromatography (HPLC) on reverse-phase columns, then quantified by HPLC with an electrochemical detector. The amounts of PBTA-1 and PBTA-2 in the water samples were < 0.01-1.91 and < 0.01-2.25 ng/L, respectively. High levels of PBTA-1 and PBTA-2 were detected in the samples collected within 4 km downstream of two sewage plants, which are located along the banks of the Nishitakase River, a tributary of the Yodo River system, and these samples showed stronger mutagenicity in Salmonella typhimurium YG1024 with S9 mix than the other water samples. On the other hand, the river water samples from upstream of the sewage plant were weakly or not mutagenic and PBTA-1 and PBTA-2 were not detected. These results confirmed that a major source of PBTA-1 and PBTA-2 in the Yodo River system is effluent from the sewage plants and that discharged mutagens, including PBTA-1 and PBTA-2, are diluted and/or decomposed while moving down the Yodo River system.

Chromatography, High Pressure Liquid↗
PubMed1999

Familial hypercholesterolemia in Utah kindred with novel 2412-6 Ins G mutations in exon 17 of the LDL receptor gene.

Familial hypercholesterolemia (FH) is a monogenic disorder associated with primary hypercholesterolemia. FH is characterized by autosomal co-dominant inheritance with strikingly elevated LDL-cholesterol, the presence of xanthoma and premature atherosclerosis. 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 from the family for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein receptor (LDLR) gene. Novel point mutations were identified in the proband: a one-base insertion of G to a five-G stretch at nucleotides 2412-6 (codons 783-785), causing a frameshift in exon 17 of the LDL receptor gene. The direct sequencing method was used to examine six members of the family recruited for the diagnosis. This method helped to unequivocally diagnose the five individuals as heterozygous for this particular LDL receptor mutation. This method also helped us to diagnose with FH, or to exclude from carrier status, three children between ages 6 and 11.

Child↗
PubMed1999

Familial hypercholesterolemia in Utah kindred with novel R103W mutations in exon 4 of the LDL receptor gene.

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein cholesterol levels early in childhood and very early coronary disease in both men and women. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. 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 carry out molecular genetic diagnosis of the disease, 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 C-to-T transversion at nucleotide position 369, causing substitution of Tryptophan for Arginine at codon 103 in exon 4 of the LDL receptor gene. The SSCP method was used to examine seven members of the family recruited for the diagnosis. This method helped to unequivocally diagnose only the proband as heterozygous for this particular LDL receptor mutation while excluding the remaining six individuals from carrier status with FH.

Adolescent↗
PubMed1999

Improved efficiency of hypervolemic therapy with inhibition of natriuresis by fludrocortisone in patients with aneurysmal subarachnoid hemorrhage.

OBJECT: To reduce the risk of ischemic complications in patients with subarachnoid hemorrhage (SAH), hypervolemic therapy is generally advocated. However, such conventional treatment cannot always ensure the maintenance of an effective intravascular volume expansion, because excessive natriuresis and osmotic diuresis occur after SAH. In this prospective study the authors examined the effects of inhibition of natriuresis with fludrocortisone acetate on intravascular volume expansion during hypervolemic therapy. METHODS: Thirty patients with SAH were randomized and divided into two groups: controls (Group 1, 15 patients) and patients treated with 0.3 mg/day of fludrocortisone (Group 2, 15 patients). In all patients sodium and fluid intake levels were in excess of maintenance requirements in an attempt to maintain a positive water balance and a central venous pressure (CVP) of 8 to 12 cm H2O. The mean sodium and water intake levels for 14 days after SAH were significantly reduced by fludrocortisone in Group 2 (487+/-34.52 mEq/day and 5159.2+/-249.29 ml/day, respectively; p<0.01) compared with Group 1 (634.2+/-42.86 mEq/day and 6611.7+/-365.67 ml/day). Fludrocortisone significantly reduced the urinary sodium excretion (p<0.01) and urine volume (p<0.01) in parallel, and effectively prevented a negative shift in the sodium as well as water balance (p<0.01). The serum sodium level tended to decrease in Group 1, reaching 135 mEq/L on average, but not in Group 2 (p<0.01). Hyponatremia in Group 1 was always observed at the optimal range of CVP values. A decrease in serum potassium level within the range of 2.8 to 3.5 mEq/L was transiently noted in 11 patients (73.3%) of Group 2, but was easily corrected. Possible side effects of fludrocortisone, such as pulmonary edema, were not encountered. CONCLUSIONS: Intravascular volume expansion in the presence of excessive natriuresis requires a large sodium and water intake and is often associated with hyponatremia. Inhibition of natriuresis with fludrocortisone can effectively reduce the sodium and water intake required for hypervolemia and prevent hyponatremia at the same time.

Adult↗
PubMed1999

[Clinical studies of faropenem in the field of obstetrics and gynecology].

The clinical effect of faropenem was evaluated in 165 ambulatory patients with various infections in the field of obstetrics and gynecology at 10 institutions in Yamagata Prefecture. The results obtained are summarized below. 1. The rate of efficacy, as determined from the clinical effect following 3- to 7-day repeated administration at a dose of 600 mg/day, was 97.9% (46/47) for intrauterine infections, 92.0% (23/25) for adnexitis, 93.8% (15/16) for external genital infections, 88.9% (8/9) for mastitis, 94.0% (63/67) for cystitis, and 100% (1/1) for cervicitis. The overall efficacy rate was estimated to be 94.5% (156/165). 2. The rate of clinical efficacy, as classified by isolate, was high, 95.1% for Gram-positive bacteria, 100% for Gram-negative bacteria, and 100% for anaerobes. As for bacteriological response classified by isolate, the eradication rate was high, 91.4% (74/81) for Gram-positive bacteria, 98.4% (62/63) for Gram-negative bacteria, 89.5% (17/19) for anaerobes, and 93.9% (153/163) in all. 3. No adverse reactions or laboratory abnormalities were observed in any patient. The results presented suggest that faropenem is a highly safe and effective antibiotic for the treatment of obstetric or gynecological infections of various kinds in an ambulatory setting.

Adult↗
PubMed1999

Surgical management of arteriosclerotic coronary artery aneurysm.

A 60-year-old man suffered antero-septal myocardial infarction at the age of 56. Coronary angiography demonstrated total occlusion of the left anterior descending artery and a large saccular aneurysm of the right coronary artery. Diffuse coronary ectasia was also shown in the right coronary artery adjacent to the aneurysm. Despite anticoagulant therapy, the aneurysm formed a thrombus and developed coronary artery stenosis distal to the aneurysm. Ligation of the aneurysm and in situ gastroepiploic artery grafting were performed. Sudden heart failure was developed during skin closure. As this condition was considered to be graft hypoperfusion, supplemental saphenous vein grafting was placed. Ligation is a simple, reliable technique to prevent future complications for a large saccular right coronary artery aneurysm, however, gastroepiploic artery might be an inappropriate bypass conduit for the ligated coronary artery with diffuse ectasia.

Arteries↗
PubMed1999

Divergence of virulence factors of Helicobacter pylori among clinical isolates does not correlate with disease specificity.

The aim of this study was to examine the relation between disease specificity and the virulence factors of Helicobacter pylori isolated from patients with gastric cancer (GC), duodenal ulcer (DU), and gastritis (GS). Altogether 18 isolates obtained from patients with GC, 28 isolates from DU patients, and 13 isolates from GS patients were analyzed. All isolates were tested for the presence of the cagA gene, and genotyping of the vacA gene was done by the polymerase chain reaction. Production of VacA protein and expression of vacuolating cytotoxic activity in the H. pylori culture supernatant were examined. The serum antibody titers against purified VacA and CagA proteins were determined by enzyme-linked immunosorbent assay (ELISA). Interleukin-8 (IL-8) production by AGS cells in response to H. pylori isolates was measured by an hIL-8 ELISA kit. Genetic analysis of vacA revealed that most of the clinical isolates were classified into the S1a type by signal sequence typing. There were no differences in cagA detection rates, vacuolating cytotoxin activity, or mean antibody titers against VacA and CagA protein among the three groups. The mean IL-8 concentrations in the supernatants of AGS cells were similar in the three groups. In this study, there was no difference in virulence factors of H. pylori among isolates from GC, DU, and GS.

Antigens, Bacterial↗
PubMed1999

[Diagnostic significance of urinary immunoglobulin G in diabetic nephropathy].

An early manifestation of diabetic nephropathy, increased excretion of albumin, is now generally believed to be sufficiently specific, particularly in subjects with diabetes mellitus, to predict the subsequent development of clinically overt diabetic nephropathy. However, certain other proteins besides albumin may also be excreted in abnormal amounts during this early phase of diabetic nephropathy. We evaluated the diagnostic utility of urinary immunoglobulin G (IgG) in patients with diabetic nephropathy by comparing the findings with the clinical stage and renal biopsy specimen. Using 24-hour urine samples, IgG was measured by an enzyme-linked immunosorbent assay. In addition, urine samples were assayed for albumin, transferrin, beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase. Serum IgG concentration and HbA1c were also evaluated. A total of 197 patients with non-insulin-dependent diabetes mellitus were enrolled in this study. Subjects were grouped according to the rate of urinary albumin excretion (clinical stage). Fifty of these cases were also divided into four groups according to the severity of diffuse glomerular lesions using Gellman's criteria. The urinary excretion of IgG was significantly increased in diabetic patients as compared with the healthy controls. Among diabetic patients, IgG level showed a significant increase with respect to the clinical stage of nephropathy and the progress of glomerular diffuse lesions. In the stage of normoalbuminuria, the urinary excretion of IgG showed a significant increase in parallel with the progress of glomerular diffuse lesions, whereas there was no relationship between the urinary excretion of albumin and the progress of glomerular diffuse lesions. While the excretion of IgG correlated with that of albumin and transferrin, there was no correlation between the excretion of IgG and the other laboratory indices evaluated. These findings indicate that measurement of urinary IgG may be more useful than albuminuria in detecting the early stage of diabetic nephropathy.

Aged↗
PubMed1998

Importance of hydrophobic region in amphiphilic structures of alpha-helical peptides for their gene transfer-ability into cells.

It has been showned that cationic alpha-helical peptides can be useful as nucleic acid-carrier molecules for gene transfer into cells. In order to investigate the significancemake sure of importance of the hydrophobic region in amphiphilic peptides in relation to their transfection ability, we have employed five kinds of peptides with a systematically varied hydrophobic-hydrophilic balance in the amphiphilic structures, and have evaluated the relationship between the structure and the gene transfer ability of the peptides into COS-7 cells. The peptides with a large hydrophobic region took alpha-helical structures, formed large aggregates and showed high transfection efficiency. Their high efficiency can be explained on the basis of their ability to form stable aggregates which can be internalized by endocytosis and remain resistant to digestion in lysosomal vesicles. Furthermore, it was suggested that the hydrophobic region of peptides plays an important role in the disruption of the endosomal membrane, which ca prevent the degradation of DNA in lysosomal vesicles. When peptides do not have so strong membrane-disruptive activity, but form aggregates which can be incorporated by endocytosis, the transfection efficiency can be recovered by the addition of an endosome-disruptive peptide.

Amino Acid Sequence↗
PubMed1998

[The effect of intraoperative high-dose tranexamic acid on blood loss after operation for acute aortic dissection].

The effect of high dose tranexamic acid on blood loss after operations for acute aortic dissection was evaluated. Twenty-eight patients undergoing emergent operations for acute aortic dissection were studied. There were two groups, group T with 13 patients (group T) who were given 7 g of tranexamic acid after induction of anesthesia and 3 g of it after CPB and group C with 15 patients who did not receive tranexamic acid. There was a tendency that group T had less bleeding during operation and after operation (559.6 +/- 865.8 ml in group T and 805.8 +/- 442.9 ml in group C, 1719.2 +/- 1008.7 ml in group T and 3547.7 +/- 4580.1 ml in group C, respectively), but there was no significant difference between two groups. The removal of drainage tubes after operation was significantly earlier in group T (5.0 +/- 2.3 post operative day in group T and 8.1 +/- 5.2 post operative day in group C; p < 0.05). FDP and D-dimer level as measures of fibrinolytic activity were elevated at pre- and postoperative period in both groups, but they tended to be lower in group T at postoperative period. One patient required reexploration because of excessive bleeding and no mediastinal infection was reported in group T, whereas 4 patients underwent reexploration and 2 patients developed mediastinitis in group C. There were 5 hospital death (33.3%) in group C and 2 (15.4%) in group T. High dose of tranexamic acid seems to control fibrinolytic activity, thereby reducing blood loss and requirements, which may contribute to lower morbidity and mortality in operations for acute aortic dissection.

Acute Disease↗
PubMed1998

Five familial hypercholesterolemic kindreds in Japan with novel mutations of the LDL receptor gene.

In the course of investigations of familial coronary artery disease in Hokkaido, the northern island of Japan, we identified five families in which multiple members showed elevated plasma levels of low-density lipoprotein (LDL) cholesterol. To determine the genetic etiology of their lipoprotein abnormalities, we screened DNA samples from these families for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor (LDLR) gene. Novel point mutations were identified in each family: (1) a C-to-A transversion at nucleotide 285, causing a nonsense mutation at codon 74, in eight members of family A; (2) a G-to-A transition at nucleotide 1136, causing substitution of Tyr for Cys at codon 358, in six members of family B; (3) a C-to-T transition at nucleotide 1822, causing substitution of Ser for Pro at codon 587, in five members of family C; (4) a one-base insertion of G to a five-G stretch at nucleotides 1774-1778 (codons 571-572), causing a frameshift, in six members of family D; and (5) a one-base deletion of T at nucleotide 1963-1964 (codon 634), causing a frameshift, in three members of family E. Through the molecular genetic approach a total of 28 individuals in these families were diagnosed unequivocally as heterozygous for the respective LDLR mutations. This method also helped us to diagnose familial hypercholesterolemia, or to exclude from carrier status, 11 children with borderline high cholesterol levels.

Adolescent↗
PubMed1998

Posterior interosseous nerve palsy.

Eleven patients with non-traumatic paralysis of posterior interosseous innervated muscles were divided into three types, and the association between the type of paralysis and sites of compression was investigated. Type 1 (drop finger and thumb) showed a simultaneous compression of the recurrent branch and the descending branch at the entrance point and within the supinator. Type 2 (drop fingers) had compression of the recurrent branch alone, and Type 3 (drop thumb) had compression of the descending branch alone. The exit point from the supinator is considered to be the site of compression in Types 2 and 3.

Adult↗
PubMed1998

Identification of 1,6- and 1,8-dinitropyrene isomers as major mutagens in organic extracts of soil from Osaka, Japan.

The organic extracts of soil collected at parks in residential areas in Osaka and neighboring cities in the Kansai area, Japan, showed mutagenicity in Salmonella typhimurium strain TA98 in the presence or absence of a mammalian metabolic activation system (S9 mix). The soil extracts from Ibaraki and two different sites in Osaka, i.e., Sumiyoshi-ku and Minato-ku, were mutagenic in strain TA100 as well as in strain TA98. Direct-acting mutagenicity of soil extracts from Sumiyoshi-ku and Minato-ku toward strain TA98 were 66 or more times higher than that of the other cities. Both extracts exerted stronger mutagenicity in strains YG1021 and YG1024 than TA98 and TA100, and the potency was especially high in strain YG1024: Sumiyoshi-ku, 153 000 revertants/g of soil; and Minato-ku, 246 000 revertants/g of soil. Two mutagenic compounds (I and II) were isolated from the Soxhlet extract of soil from the park in Sumiyoshi-ku by repetitive separation using normal-phase and reversed-phase column chromatography. By comparing the mass and UV spectra and retention times for HPLC on two individual ODS columns of compounds I and II with those of authentic chemicals, we identified these two compounds as 1,6- and 1,8-dinitropyrene (DNPy) isomers. Amounts of DNPy isomers in soil from Sumiyoshi-ku and Minato-ku were 1.7-2.2 ng/g. Forty-three percent and 40% of the mutagenicity of soil from Sumiyoshi-ku and Minato-ku could be attributed to these DNPy isomers, respectively.

Animals↗
PubMed1998

Partial characterization of the gametes and development of a successful in vitro fertilization procedure in the mastomys (Praomys coucha): a new species for reproductive biology research.

The mastomys, a small African rodent, has been extensively used as a laboratory animal for cancer research. Previous preliminary studies have demonstrated that the animal has a relatively short estrous cycle and that superovulation can be induced. However, biological characterization of the gametes in this species has not been done. The purpose of this study is to determine requirements for fertilization and to devise a suitable method for in vitro fertilization (IVF). Data from these studies show that 1) cauda epididymal plasma (CEP) is required for maintaining sperm motility in vitro; 2) in a heterologous sperm penetration assay in vitro, optimal conditions for sperm capacitation and the acrosome reaction depend on time and CEP concentration; and 3) loss of the cortical granules is observed to occur spontaneously within 3-4 h after ovulation in superovulated eggs. On the basis of the data obtained from these studies, we have developed a method for preincubation of mastomys sperm and a successful mastomys IVF procedure. This species can now be used as a new laboratory animal for research in reproductive biology.

Acrosome↗