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Biomedical subjects

S Ueda

Publications and source records attributed to S Ueda.

At least 19 recordsLinked to original sources
PubMed1999

Effects of cytosolic Ca2+ on membrane voltage and conductance of cultured mesangial cells from stroke-prone spontaneously hypertensive rats and WKY rats.

Mesangial cells (MC) are considered to play an important role in the development of hypertension. The purpose of this study was to characterize the effects of cytosolic Ca2+ on membrane voltage and conductance of MC using stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY). We applied the patch-clamp technique in the whole-cell configuration to measure membrane potential (Vm) and ion currents. There was no significant difference in resting Vm values between MC from WKY and SHRSP. The cytosolic Ca2+ increase induced membrane depolarization and the increase of Cl- currents in MC from WKY but not in MC from SHRSP. On the other hand, the Ca2+ increase induced membrane hyperpolarization and the increase of K+ currents in MC from SHRSP but not in MC from WKY. Such differences between MC from two rat strains may play an important role in the alterations in renal hemodynamics observed in hypertension.

Animals↗
PubMed1999

Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis.

BACKGROUND: Exposure to risk factors such as hypertension or hypercholesterolemia decreases the bioavailability of endothelium-derived nitric oxide (NO) and impairs endothelium-dependent vasodilation. Recently, a circulating endogenous NO synthase inhibitor, asymmetric dimethylarginine (ADMA), has been detected in human plasma. The purpose of this study was to examine the relationship between plasma ADMA and atherosclerosis in humans. METHODS AND RESULTS: Subjects (n=116; age, 52+/-1 years; male:female ratio, 100:16) underwent a complete history and physical examination, determination of serum chemistries and ADMA levels, and duplex scanning of the carotid arteries. These individuals had no symptoms of coronary or peripheral artery disease and were taking no medications. Univariate and multivariate analyses revealed that plasma levels of ADMA were positively correlated with age (P<0.0001), mean arterial pressure (P<0.0001), and Sigma glucose (an index of glucose tolerance) (P=0.0006). Most intriguingly, stepwise regression analysis revealed that plasma ADMA levels were significantly correlated to the intima-media thickness of the carotid artery (as measured by high-resolution ultrasonography). CONCLUSIONS: This study reveals that plasma ADMA levels are positively correlated with risk factors for atherosclerosis. Furthermore, plasma ADMA level is significantly correlated with carotid intima-media thickness. Our results suggest that this endogenous antagonist of NO synthase may be a marker of atherosclerosis.

Adult↗
PubMed1999

Histopathological features of liver damage induced by laser ablation in rabbits.

BACKGROUND AND OBJECTIVE: Possible mechanisms that promote or interfere with the effects of laser ablation of the liver have not been clarified. The aim of this study was to define the chronological alterations in the normal rabbit liver at early stages after laser ablation. STUDY DESIGN/MATERIALS AND METHODS: Rabbit livers were ablated with a laser via an optical fiber and then analyzed histopathologically by immunostaining for heat shock protein 70 (HSP70) and by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. RESULTS: The lesions increased in size progressively over the 24 h that followed ablation and the area of the lesion coincided with the area that had been heated above 43 degrees C. TUNEL-positive hepatocytes were surrounded, at some distance, by HSP70-positive hepatocytes were surrounded, at some distance, by HSP70-positive hepatocytes at 6 h, and such cells were in contact with each other at 24 h. CONCLUSIONS: Injury to hepatocytes induced by laser ablation increases for 24 h and dying cells express nuclear HSP70, with subsequent fragmentation of DNA.

Animals↗
PubMed1999

Comparison of adjuvants with respect to serum IgG antibody response in orally immunized chickens.

We have previously shown that oral immunization with non-replicating antigens hardly induced serum IgG antibody response in chickens and addition of sodium fluoride (NaF) to the immunogen markedly improved their immunological states. In the present study, taurine, lithium and Quillaja saponin (Q-SAP) were compared with NaF with respect to their enhancement of serum IgG antibody response in chickens after oral immunization. The antibody titer of chickens which received Q-SAP as the mucosal adjuvant tended to be higher than that of chickens which received antigen plus NaF. Simultaneous administration of antigen with lithium or taurine elicited a higher antibody titer in chickens compared to those of chickens orally immunized with antigen alone, but the effect of these two adjuvants was less efficient compared with that of NaF. These results suggested that Q-SAP as well as NaF is useful as an oral adjuvant for chickens.

Adjuvants, Immunologic↗
PubMed1999

Molecular genetic analysis of remains of a 2,000-year-old human population in China-and its relevance for the origin of the modern Japanese population.

We extracted DNA from the human remains excavated from the Yixi site ( approximately 2,000 years before the present) in the Shandong peninsula of China and, through PCR amplification, determined nucleotide sequences of their mitochondrial D-loop regions. Nucleotide diversity of the ancient Yixi people was similar to those of modern populations. Modern humans in Asia and the circum-Pacific region are divided into six radiation groups, on the basis of the phylogenetic network constructed by means of 414 mtDNA types from 1, 298 individuals. We compared the ancient Yixi people with the modern Asian and the circum-Pacific populations, using two indices: frequency distribution of the radiation groups and genetic distances among populations. Both revealed that the closest genetic relatedness is between the ancient Yixi people and the modern Taiwan Han Chinese. The Yixi people show closer genetic affinity with Mongolians, mainland Japanese, and Koreans than with Ainu and Ryukyu Japanese and less genetic resemblance with Jomon people and Yayoi people, their predecessors and contemporaries, respectively, in ancient Japan.

Asian People↗
PubMed1999

Isolation from tobacco mosaic virus-infected tobacco of a solubilized template-specific RNA-dependent RNA polymerase containing a 126K/183K protein heterodimer.

The complete nucleotide sequence was determined for the putative RNA polymerase (183K protein) gene of tobacco mosaic virus (TMV) OM strain, which differed from the related strain, vulgare, by 51 positions in its nucleotide sequence and 6 residues in its amino acid sequence. Three segments of this 183K protein, each containing the sequence motif of methyltransferase (M), helicase (H), or RNA-dependent RNA polymerase (P), were expressed in Escherichia coli as fusion proteins with hexahistidine tags, and domain-specific antibodies were raised against purified His-tagged M and P polypeptides. By immunoaffinity purification, a template-specific RNA-dependent RNA polymerase containing a heterodimer of the full-length 183K and 126K (an amino-terminal-proximal portion of the 183K protein) viral proteins was isolated. We propose that the TMV RNA polymerase for minus-strand RNA synthesis is composed of one molecule each of the 183- and 126-kDa proteins, possibly together with two or more host proteins.

Base Sequence↗
PubMed1999

Insulin-mediated vasodilation and glucose uptake are functionally linked in humans.

Intra-arterial infusion of insulin in physiological doses causes forearm vasodilation which is augmented by co-infusion of D-glucose, leading us to speculate that local insulin-mediated vasodilation may depend on insulin-mediated glucose uptake. We have examined the relationship between whole-body insulin sensitivity and forearm vasodilation in response to local infusion of insulin/glucose, thus avoiding any confounding effects of sympathetic stimulation on peripheral blood flow. Eighteen healthy, normotensive male volunteers (age, 26+/-5.4 years) attended on two separate occasions for measurement of: (1) whole-body insulin sensitivity with use of the hyperinsulinemic euglycemic clamp; (2) forearm vasodilation in response to an intra-arterial infusion of insulin/glucose with use of bilateral venous occlusion plethysmography. Insulin-mediated glucose uptake (M) for the group (mean+/-SD) was 10.0+/-2.2 mg. kg-1. min-1, and the percentage change in forearm blood flow ratio (%FBFR) for the group (median, interquartile range) was 28.2% (13.6, 48.6). In univariate analysis, M was significantly correlated with %FBFR (rs=0.60, P<0.05), but not with body mass index (BMI) (rs=-0. 42), age (r=-0.39) or mean arterial pressure (r=0.13). In multiple regression analysis, %FBFR remained a significant independent predictor of M (R2 (adj)=0.48, t=3.23, P<0.01) in a model involving BMI, age, and blood pressure. These data support the concept of a significant functional relationship between insulin's metabolic and vascular actions, possibly at an endothelial level.

Adult↗
PubMed1999

Effect of mutations at the residues R25, D27, P69, and N70 of B95a-MCP on receptor activities for the measles viruses Nagahata wild-type strain and CAM vaccine strain.

Human membrane cofactor protein (MCP, CD46) is a regulator of complement activation and also serves as a receptor for measles virus (MV). We recently isolated an MCP homolog from B95a, an Epstein-Barr virus-transformed marmoset B-lymphoblastoid cell line, which is 76% identical to human-MCP. B95a-MCP acts as an MV receptor for CAM, a vaccine strain of MV, but not for Nagahata, wild-type MV strain. The four residues in human-MCP (Asp27, Lys29, Arg69, and Asp70) are reportedly MV binding sites, and these are changed in B95a-MCP (Glu27, Asp29, Pro69, and Asn70). In the present study, we constructed B95a-MCP mutants by replacing the four residues with those in human-MCP, and tested whether the Chinese hamster ovary (CHO) transfectants expressing B95a-MCP mutants become susceptible to the Nagahata strain. The CHO transfectants expressing B95a-MCP mutants formed syncytium with the CAM strain but not with the Nagahata strain. The binding of the hemagglutinin (H) of MV with B95a-MCP mutants was observed with the CAM strain but not with the Nagahata strain. These results suggest that the failure of B95a-MCP as the MV receptor for the Nagahata strain is not due simply to the natural mutations at these four residues. The critical residues for MV binding in an MCP molecule seem to differ depending upon the structure of the MV H protein.

Amino Acid Sequence↗
PubMed1999

Endothelial dysfunction by acute hyperhomocyst(e)inaemia: restoration by folic acid.

Recent evidence demonstrates that hyperhomocyst(e)inaemia is a novel risk factor for cardiovascular diseases. In patients with chronic hyperhomocyst(e)inaemia, endothelial function is impaired. However, whether hyperhomocyst(e)inaemia per se is a cause or an epiphenomenon of endothelial dysfunction remains unknown. In this study, we examined the effects of methionine-induced acute hyperhomocyst(e)inaemia on human endothelial function. In healthy volunteers we administered methionine (0.1 g/kg body weight, per os), a substrate of homocyst(e)ine, with or without folic acid (20 mg, per os) and examined flow-mediated vasodilatation of the brachial artery by high-resolution ultrasonography as a non-invasive measure of endothelial function. We also measured plasma levels of homocyst(e)ine before and 3, 8 and 24 h after methionine loading. Methionine administration increased plasma levels of homocyst(e)ine by four times the basal level at 8 h (P<0.0001, ANOVA). The plasma levels returned to baseline at 24 h. Flow-mediated vasodilatation was significantly decreased to half of the baseline value at 8 h and returned to baseline at 24 h (P<0.0001, ANOVA), whereas endothelium-independent vasodilatation by glyceryl trinitrate was not affected by the methionine loading. Co-administration of folic acid did not attenuate methionine-induced hyperhomocyst(e)inaemia but completely prevented endothelial dysfunction. Our results suggest that in humans a methionine-rich diet may acutely impair endothelial function, which can be prevented by folic acid supplementation.

Acute Disease↗
PubMed1999

[Thoraco-abdominal impalement injury with diaphragmatic injury: a case report].

A 60-year-old man was admitted to our hospital because of impalement injury due to traffic accident. Chest X-ray on admission revealed normal lung field. CT scans of the chest and abdomen revealed slight pneumothorax and intra-abdominal organ protruding from abdominal cavity. An emergency operation was performed. Diaphragmatic injury was not detected during the abdominal procedure. On exploring the back wound, we found a laceration of 8 cm in diameter in the diaphragm and repaired it. Impalement injuries which have aspects of both blunt and penetrating trauma are uncommon. Accordingly, wound exploration and debridement of fistulous tract are necessary. In the case of thoraco-abdominal injuries by impalement, one should bear in mind the existence of diaphragmatic injury even with normal diaphragmatic shadow on chest X-ray.

Abdominal Injuries↗
PubMed1998

The development of autoimmune inflammatory arthropathy in mice transgenic for the human T cell leukemia virus type-1 env-pX region is not dependent on H-2 haplotypes and modified by the expression levels of Fas antigen.

Previously, we reported that human T cell leukemia virus type-1 env-pX region-introduced transgenic (pX-Tg) mice develop an inflammatory polyarthropathy. Although autoimmune pathogenesis was suggested, the detailed mechanisms remain to be elucidated. In this report, we examined effects of the MHC and fas genes on the development of the disease. When pX-Tg mice were backcrossed with different inbred strains, the incidence of arthritis differed among strains; 64% and 72% in BALB/cAn (H-2d), 25% and 46% in C3H/HeN (H-2k), and 0% and 2% in C57BL/6J (H-2b) background at 3 and 6 months of age, respectively. Rheumatoid factor levels in the serum correlated with the susceptibility to the disease, whereas IL-1beta and MHC gene expression were similarly elevated in all of these strains, suggesting involvement of immune regulatory genes in this strain difference. However, introduction of the H-2d locus into C57BL/6J pX-Tg mice did not increase the incidence of arthritis, and substitution of the BALB/cAn H-2 locus with the H-2b did not decrease it. The results indicate that the H-2 locus is not the major determinant of the disease. Then, since previous study indicated a defect in Fas-mediated apoptosis of transgenic T cells, the effects of fas gene modification on the disease were examined. The incidence increased when these pX-Tg mice were crossed with lpr/lpr mice, while it decreased when crossed with fas-transgenic mice. These observations suggest that aberration of Fas-mediated apoptosis of peripheral lymphocytes, rather than negative selection in the thymus, is involved in the development of autoimmune arthropathy in pX-Tg mice.

Animals↗
PubMed1998

Redox regulation of caspase-3(-like) protease activity: regulatory roles of thioredoxin and cytochrome c.

Oxidative stress induces a variety of cellular responses, including apoptosis, and caspase family proteases are known to be involved in apoptosis. Caspase-3(-like) protease activity was examined in Jurkat T cells to investigate the mechanism of apoptosis induced by a thioloxidant, diamide. Caspase-3 was activated when cells were cultured with 200 microM diamide that induced apoptosis, whereas no caspase-3 activation was detected with 500 microM diamide that induced necrosis. When apoptosis was induced in cells with exposure to 200 microM diamide, the intracellular thioredoxin (TRX) levels were maintained and the intracellular generation of reactive oxygen intermediates was marginal. The cytosolic fractions of cytochrome c were increased earlier than the activation of caspase-3. In contrast, when cells were exposed to 500 microM diamide, intracellular reactive oxygen intermediate generation was increased and processing of caspase-3 was not detected despite cytochrome c release, resulting in necrosis. Caspase-3 activity in cell lysate precultured with anti-Fas Ab was suppressed dose dependently by diamide and restored by thiol-reducing agents, DTT or TRX. When cells were precultured with 5 mM of buthionine sulfoximine, an inhibitor of glutathione synthesis, intracellular TRX levels were maintained, and as low as 20 microM diamide could induce apoptosis associated with the increase of cytosolic cytochrome c and the activation of caspase-3. These results indicate that the activation of caspase-3 in diamide-induced apoptosis is mediated, at least partly, by cytochrome c release from mitochondria, and the cellular reducing environment maintained by TRX, as well as glutathione, is required for caspase-3 activity to induce apoptosis.

Antibodies, Monoclonal↗
PubMed1998

ACE (I/D) genotype as a predictor of the magnitude and duration of the response to an ACE inhibitor drug (enalaprilat) in humans.

BACKGROUND: We have investigated the possible effects of contrasting ACE (I/D) genotypes on the responses to the ACE inhibitor enalaprilat in normotensive men. METHODS AND RESULTS: Subjects with DD (n=12) and II (n=11) ACE genotypes received an intravenous infusion of enalaprilat or placebo. Pressor responses to stepwise, incremental doses of angiotensin I were measured at 1 and 10 hours after dosing. The dose required to raise mean blood pressure by 20 mm Hg (PD20) was calculated individually, and the ratio of PD20 during enalaprilat to that during placebo (dose ratio, DR) was used for assessment of the extent of ACE inhibition. The pressor response was significantly attenuated at 1 hour after enalaprilat in both groups, but significant attenuation was evident at 10 hours after dose only in the II subjects. The DRs at both 1 hour (median, 5.43 versus 2.82, P=0.0035) and 10 hours (2.06 versus 0.84, P=0.0008) after enalaprilat were significantly higher in II subjects than in DD subjects. CONCLUSIONS: The effect of enalaprilat was significantly greater and lasted longer in normotensive men homozygous for the II ACE genotype. By multivariate analysis, ACE (I/D) genotype and plasma angiotensin II levels were predictive of >50% of the variation in response to ACE inhibition.

Adult↗
PubMed1998

Activation of cAMP-dependent C1- currents in guinea-pig paneth cells without relevant evidence for CFTR expression.

1. To determine whether Paneth cells exhibit functional expression of cAMP-activated Cl- currents and molecular expression of the cystic fibrosis transmembrane conductance regulator (CFTR), we applied whole-cell patch clamp and single-cell mRNA analysis by reverse transcription (RT) followed by polymerase chain reaction (PCR) amplification to single Paneth cells in crypts isolated from the guinea-pig small intestine. 2. Prominent activation of Cl- currents was consistently observed after stimulation with dibutyryl cAMP and forskolin or with vasoactive intestinal polypeptide (VIP). The cAMP-activated Cl- current was inhibited by removal of intracellular ATP or administration of an inhibitor of protein kinase A. 3. Many of the biophysical and pharmacological properties of the currents were phenotypically similar to those of the CFTR Cl- channel, such as the ohmic current-voltage relationship, the anion selectivity with a Type III sequence (Br- > Cl- > I- >> F- >= gluconate-), I--induced blockage, insensitivity to a stilbene-derivative Cl- channel blocker, and sensitivity to a carboxylate analogue Cl- channel blocker. The sensitivity of the current to glibenclamide was, however, much weaker than that reported for the CFTR Cl- channel current. In contrast to the time independence of CFTR currents, the inward component of the Paneth cell Cl- currents exhibited inactivation kinetics. 4. Expression of CFTR mRNA could not be detected by RT-PCR analysis in almost all single Paneth cells, although its expression was consistently detected at the whole-crypt level. The presence of a small number of CFTR-expressing epithelial cells, which were scattered both in villi and crypts but not at the crypt base where Paneth cells were located, was demonstrated by immunocytochemistry. 5. Taken together, it appears that guinea-pig Paneth cells functionally express cAMP-activated Cl- conductance without relevant evidence for molecular expression of CFTR. Functional expression of VIP receptors in the Paneth cells was also demonstrated.

Animals↗
PubMed1998

Novel, highly potent aldose reductase inhibitors: (R)-(-)-2-(4-bromo-2-fluorobenzyl)-1,2,3,4- tetrahydropyrrolo[1,2-a]pyrazine -4-spiro-3'-pyrrolidine-1,2',3,5'-tetrone (AS-3201) and its congeners.

A series of novel tetrahydropyrrolo[1,2-a]pyrazine derivatives were synthesized and evaluated as aldose reductase inhibitors (ARIs) on the basis of their abilities to inhibit porcine lens aldose reductase (AR) in vitro and to inhibit sorbitol accumulation in the sciatic nerve of streptozotocin-induced diabetic rats in vivo. Of these compounds, spirosuccinimide-fused tetrahydropyrrolo[1, 2-a]pyrazine-1,3-dione derivatives showed significantly potent AR inhibitory activity. In the in vivo activity of these derivatives, 2-(4-bromo-2-fluorobenzyl)-1,2,3,4-tetrahydropyrrolo[1, 2-a]pyrazine-4-spiro-3'-pyrrolidine-1,2',3,5'-tetrone (23t) (SX-3030) showed the best oral activity. The enantiomers of 23t were synthesized, and the biological activities were evaluated. It was found that AR inhibitory activity resides in the (-)-enantiomer 43 (AS-3201), which was 10 times more potent in inhibition of the AR (IC50 = 1.5 x 10(-8) M) and 500 times more potent in the in vivo activity (ED50 = 0.18 mg/kg/day for 5 days) than the corresponding (+)-enantiomer 44 (SX-3202). From these results, AS-3201 was selected as the candidate for clinical development. The absolute configuration of AS-3201 was also established to be (R)-form by single-crystal X-ray analysis. In this article we report the preparation and structure-activity relationship (SAR) of tetrahydropyrrolopyrazine derivatives including a novel ARI, AS-3201.

Aldehyde Reductase↗
PubMed1998

Gene dosage effects on polyhydroxyalkanoates synthesis from n-alcohols in Paracoccus denitrificans.

Putative promoters of polyhydroxyalkanoate (PHA)-synthetic genes of Paracoccus denitrificans were identified. Gene dosage effects for PHA synthesis were investigated in recombinants of P. denitrificans with increased expression levels of each PHA synthetic enzyme. In the cultivation of shake flasks using ethanol or n-pentanol as carbon source, a self-cloning recombinant of the phaC-encoding PHA synthase showed the highest contents [(g PHA). (g total biomass)-1] and the highest rates of PHA accumulation [(g PHA). (g residual biomass)-1. h-1] among these recombinants. The PHA content and PHA accumulation rate (g PHA/g residual biomass. h-1) of the self-cloning recombinant was 2 and 2.7 times higher, respectively, than that of the wild strain. This result strongly suggests that the step of PHA synthase is limited in in vivo PHA synthesis from n-pentanol via 3-ketovaleryl-CoA through beta-oxidation, and from ethanol via acetyl-CoA. Studies on fed-batch cultures keeping the alcohol concentration constant (0.02%) in a 5-L bioreactor showed that the ability of PHA biosynthesis was improved by the gene dosage of PHA synthase, although the growth rate of cells during the growth-associated PHA synthesis phase was retarded. The molecular weight of the polymer isolated from the strain, dosed by the PHA synthase gene, was lower than that of the polymer from the wild strain, indicating that the amount of PHA synthase in vivo affects the molecular weight of the polymer.

3-Hydroxybutyric Acid↗
PubMed1998

The possible effect of nitric oxide on relaxation and noradrenaline release in the isolated rabbit urethra.

We evaluated the effects of N(omega)-nitro-L-arginine (L-NNA, a nitric oxide (NO) synthase inhibitor) and carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO, a NO scavenger) on NO-mediated relaxation and noradrenaline release from adrenergic nerve endings induced by electrical field stimulation in the rabbit urethra. Electrical field stimulation caused frequency-dependent relaxation of rabbit urethral smooth muscles precontracted with phenylephrine. The relaxation responses were significantly inhibited by treatment with L-NNA or carboxy-PTIO. The inhibitory effect of carboxy-PTIO was significantly weaker than that of L-NNA. Electrical field stimulation caused significant noradrenaline release from adrenergic nerve endings in the rabbit urethra. Treatment with carboxy PTIO enhanced electrical field stimulation-induced noradrenaline release, and simultaneous application of L-NNA and carboxy-PTIO did not further enhance noradrenaline release in the rabbit urethra. As carboxy-PTIO reacts only with the free radical NO, the present results suggest that free radical NO and NO-containing compounds are involved in the L-NNA-sensitive nitrergic nerve-mediated relaxation in the rabbit urethra. At the same time free radical NO has a prejunctional action by which it may inhibit noradrenaline release from adrenergic nerves.

Animals↗