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Biomedical subjects

Yasuyoshi Ouchi

Publications and source records attributed to Yasuyoshi Ouchi.

At least 73 records · Page 4Linked to original sources
PubMed2003

Reduced endothelial vasomotor function and enhanced neointimal formation after vascular injury in a rat model of blood pressure lability.

Increased short-term blood pressure variability is known to be associated with hypertensive target organ damage. Sinoaortic denervation (SAD) induces a marked increase in blood pressure lability without affecting the average blood pressure level. The aim of this study was to investigate the effects of blood pressure lability on endothelial vasomotor function and neointimal formation after balloon injury in SAD rats. Direct longterm measurement of mean arterial pressure showed no significant difference in the average of mean arterial pressure between the SAD group and sham-operated control group. In contrast, the standard deviation of mean arterial pressure, as an index of blood pressure lability, was 3-fold greater in SAD rats. To study endothelial function, isometric tension of aortic rings was measured 4 weeks after SAD or sham operation. Endothelium-dependent vasorelaxation induced by acetylcholine was significantly reduced in the SAD group (20% reduction at maximum relaxation). Endothelium-independent vasorelaxation induced by sodium nitroprusside was similar in each group. Acetylcholine-induced NO release from aortic rings was significantly reduced in the SAD group. Next, we examined neointimal formation in carotid arteries in SAD and sham-operated rats at 2 weeks after balloon injury. The neointimal-to-medial area ratio in the SAD group was 50% higher than that in the sham-operated group. The percentage of proliferating cell nuclear antigen-positive cells in the intima was significantly higher in the SAD group. These findings suggest that increased blood pressure lability, independently of average blood pressure level, impairs endothelial function by inhibiting NO production, enhances neointimal formation after balloon injury, and may thereby contribute to atherogenesis.

Angioplasty, Balloon↗
PubMed2003

Effects of oxygen administration on the circulating vascular endothelial growth factor (VEGF) levels in patients with obstructive sleep apnea syndrome.

OBJECTIVE: Repeated nocturnal hypoxia is implicated in the pathogenesis of cardiovascular complications in obstructive sleep apnea syndrome (OSAS). We hypothesized that circulating vascular endothelial growth factor (VEGF) levels are affected by nocturnal hypoxemia in patients with OSAS. METHODS: We examined the serum VEGF levels in patients with OSAS and in control subjects. We also tested the effects of oxygen or air administration on the subjects' VEGF levels. PATIENTS AND MATERIALS: Twenty-four OSAS patients (mean age 54.2 +/- 3.6 years) and 24 age-matched control subjects (53.2 +/- 3.6 years). Their serum samples were tested. RESULTS: Serum VEGF levels at 8:00 AM were significantly higher in OSAS patients than in controls (p<0.01). VEGF levels decreased from 515 +/- 31 (pg/ml) to 178 +/- 16 (pg/m) (p<0.01) in OSAS patients whose nocturnal hypoxemia was found to be improved by administration of 2 l/min of oxygen during the night. However, the administration of compressed air affected neither the VEGF level nor nocturnal oxygen desaturation in OSAS patients. CONCLUSION: These results indicate that circulating VEGF levels are elevated in OSAS patients, primarily due to nocturnal hypoxemia.

Adult↗
PubMed2003

Preventing angiographic progression of coronary atherosclerosis with pravastatin.

We conducted a prospective study to investigate the relationship between the decrease of serum lipid levels during pravastatin therapy and changes of coronary angiography parameters in Japanese patients with coronary atherosclerosis. The patients were predominantly male, aged between 18 and 75 years (mean: 58 years), had at least 25% stenosis of one or more major coronary arteries, and had a serum total cholesterol ( TC) level > or = 200 mg/dl (5.18 mM/l). Treatment with pravastatin (10 mg/day) was continued for 3 years. Coronary angiography was performed before and 3 years after the start of pravastatin therapy to assess the relationship between the mean segment diameter (MSD), the minimal lumen diameter (MLD), and the annual changes of percent stenosis and TC levels. of 265 patients who were initially registered, 129 were followed for an average of 35 months. Consequently, second angiograms were only obtained in 68 patients for various reasons, so this group was used for analysis. During pravastatin therapy, the TC level significantly decreased from 239 mg/dl (6.19 mM/l) to 210 mg/dl (5.44 mM/l) (a 12% reduction; p<0.001). In addition, HDL-cholesterol increased by 5% (p=0.007), but the triglyceride level did not show a significant change. Both MSD and MLD were significantly improved on follow-up angiography, increasing from 2.67 mm to 2.76 mm and from 2.09 mm to 2.13 mm, respectively. However, no change of percent stenosis was observed. The mean TC level during treatment did not show any significant correlation with the changes of angiography parameters. However, a significant correlation was observed between the percent reduction of TC and the annual change of MSD (r=-0.272, p=0.027). A similar relationship was also found between the change of MLD and the percent reduction of TC (r=-0.260, p=0.035). In conclusion, the percent decrease of serum cholesterol may be a better indicator of clinical efficacy than the absolute cholesterol level during pravastatin therapy.

Coronary Angiography↗
PubMed2002

A potent inhibitor of cytosolic phospholipase A2, arachidonyl trifluoromethyl ketone, attenuates LPS-induced lung injury in mice.

Acute respiratory distress syndrome (ARDS) is an acute lung injury of high mortality rate, and sepsis syndrome is one of the most frequent causes of ARDS. Metabolites of arachidonic acid, including thromboxanes and leukotrienes, are proinflammatory mediators and potentially involved in the development of ARDS. A key enzyme for the production of these inflammatory mediators is cytosolic phospholipase A(2) (cPLA(2)). Recently, it has been reported that arachidonyl trifluoromethyl ketone (ATK) is a potent inhibitor of cPLA(2). In the present study, we hypothesized that pharmacological intervention of cPLA(2) could affect acute lung injury. To test this hypothesis, we examined the effects of ATK in a murine model of acute lung injury induced by septic syndrome. The treatment with ATK significantly attenuated lung injury, polymorphonuclear neutrophil sequestration, and deterioration of gas exchange caused by lipopolysaccharide and zymosan administration. The current observations suggest that pharmacological intervention of cPLA(2) could be a novel therapeutic approach to acute lung injury caused by sepsis syndrome.

Animals↗
PubMed2002

Induction of anti-metallothionein antibody and mercury treatment decreases bone mineral density in mice.

Mercuric chloride (HgCl2) is an industrial agent with toxic effects on the immune system, kidney, lung, and nervous tissue, but little is known about its effect on bone. Metallothionein (MT) is a cysteine-rich metal-binding protein that exerts cytoprotective effects against heavy metal toxins. It has been reported that the susceptibility of renal and pulmonary toxicity of mercury was markedly enhanced in MT-null mice compared to control mice. However, there is no report about the effects of anti-metallothionein (anti-MT) Ab induction on mercury toxicity. We investigated the effect of anti-MT Ab induction on mercury-induced bone injury. BALB/c mice were injected with MT (10 microg/mouse ic) five times to induce anti-MT Ab and then treated with HgCl2 (1 mg/kg sc) three times per week for 3 weeks. MT immunization plus HgCl2 treatment dramatically decreased bone mineral density (BMD), and the humoral bone formation indices, alkaline phosphatase (ALP) activity and osteocalcin. MT immunization or HgCl2 treatment alone did not affect either BMD or serum ALP activity and osteocalcin levels. MT immunization impeded HgCl2-induced increase of MT expression in the liver and led to an increase of mercury in serum and the liver but a decrease in the kidney. Furthermore, serum titers of IgE and IgG1 were significantly elevated in the MT-immunized plus HgCl2 treatment group compared with those in the HgCl2 treatment group. Similar results were also observed in splenic secretions of IL-4 and IL-10 based on anti-CD3 Ab stimulation. Taken together, our results indicate that anti-MT Ab induction causes mercury-induced bone injury in BALB/c mice and also enhances mercury-related immune disorders.

Alkaline Phosphatase↗
PubMed2002

Estrogen activates cyclin-dependent kinases 4 and 6 through induction of cyclin D in rat primary osteoblasts.

Estrogen plays important roles in maintaining bone density and protecting against osteoporosis, but the underlying mechanisms of estrogen action via estrogen receptors (ERs) in bone remain to be clarified. In the present study, we isolated primary osteoblasts derived from transgenic rats harboring a dominant negative ER mutant, rat ERalpha (1-535) cDNA, and from their wild-type littermates. We observed that the rate of cell growth of osteoblasts from the transgenic rats was reduced compared to that of wild-type osteoblasts. Utilizing cDNA microarray analysis, we found that mRNA level of cyclin D2 was lower in the osteoblasts from the transgenic rats. D-type cyclins including cyclin D1, cyclin D2, and cyclin D3 are cell cycle regulators that promote progression through the early-to-mid G1 phase of the cell cycle. The protein levels of D-type cyclins including cyclin D2 and cyclin D3 but not cyclin D1 were elevated in wild-type osteoblasts with 17beta-estradiol treatment, resulting in the activation of cyclin-dependent kinases 4 and 6 (Cdk4/6) activities and the promotion of cell growth. Moreover, an anti-estrogen ICI 182,780 abolished the induction of the expression of D-type cyclins by 17beta-estradiol. Our findings indicate that estrogen and its receptors enhance Cdk4/6 activities through the induction of D-type cyclins, leading to the growth promotion of osteoblasts.

Animals↗
PubMed2002

Effects of obstructive sleep apnea on circulating ICAM-1, IL-8, and MCP-1.

Obstructive sleep apnea syndrome (OSAS) is one of the most important risk factors of cardiovascular disorders. In the treatment of OSAS, nasal continuous positive airway pressure (nCPAP) has been widely used and found to be effective. In the present study, we hypothesized that the hypoxic stress caused by obstructive sleep apnea would increase circulating intercellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) in untreated OSAS patients compared with an age-matched control group. In addition, we hypothesized that nCPAP may decrease OSAS-induced hypoxic stress and mediators. To examine these hypotheses, we measured circulating ICAM-1 and IL-8 before and after nCPAP therapy in OSAS patients. We observed that nCPAP decreased apnea, desaturation, and the circulating ICAM-1 and IL-8 levels in OSAS patients. The circulating levels of ICAM-1, IL-8, and MCP-1 in untreated OSAS patients were significantly greater than those in the controls. These observations suggest that nCPAP therapy could reduce OSAS-induced hypoxia and generation of inflammatory mediators. Treatment of OSAS using nCPAP can be, therefore, a potential approach to decrease risk of the progression of OSAS-associated disorders.

Chemokine CCL2↗
PubMed2002

Identification of multiple novel epididymis-specific beta-defensin isoforms in humans and mice.

Defensins comprise a family of cationic antimicrobial peptides that are characterized by the presence of six conserved cysteine residues. We identified two novel human beta-defensin (hBD) isoforms by mining the public human genomic sequences. The predicted peptides conserve the six-cysteine motif identical with hBD-4, termed hBD-5 and hBD-6. We also evaluated the characteristics of the mouse homologs of hBD-5, hBD-6, and HE2beta1, termed mouse beta-defensin (mBD)-12, mBD-11, and mouse EP2e (mEP2e). The mBD-12 synthetic peptide showed salt-dependent antimicrobial activity. We demonstrate the epididymis-specific expression pattern of hBD-5, hBD-6, mBD-11, mBD-12, and mEP2e. In situ hybridization revealed mBD-11, mBD-12, and mEP2e expression in the columnar epithelium of the caput epididymis, contrasting with the predominant expression of mBD-3 in the capsule or septum of the whole epididymis. In addition, the regional specificity of mBD-11, mBD-12, and mEP2e was somewhat overlapping, but not identical, in the caput epididymis, suggesting that specific regulation may work for each member of the beta-defensin family. Our findings indicated that multiple beta-defensin isoforms specifically and cooperatively contribute to the innate immunity of the urogenital system.

Amino Acid Sequence↗
PubMed2002

Mouse genetic evidence that tranilast reduces smooth muscle cell hyperplasia via a p21(WAF1)-dependent pathway.

OBJECTIVE: N-(3'4'-dimethoxycinnamoyl)-anthranilic acid (tranilast) is a drug that has been shown to reduce the incidence of restenosis after angioplasty in middle-scale clinical trials. Despite clinical interest in this drug, the pharmacological actions of tranilast remain relatively unexplored at a molecular level. METHODS AND RESULTS: We evaluated the effects of tranilast on vascular smooth muscle cell (VSMC) proliferation in wild-type mice and in mice lacking a cyclin-dependent kinase inhibitor, p21(WAF1) (p21). Tranilast potently inhibited the proliferation of VSMC cultures derived from wild-type mice, but VSMCs derived from p21-deficient (p21-/-) mice were unaffected by this treatment. In a mouse femoral artery model of vascular injury, tranilast administration to wild-type mice led to an upregulation of p21 expression and a decrease in the number of proliferating VSMCs, as determined by immunostaining for proliferating cell nuclear antigen. In contrast, tranilast had no effect on the number of proliferating cell nuclear antigen-positive cells in the injured arteries of p21-/- mice. Administration of tranilast significantly reduced the neointimal VSMC hyperplasia in wild-type mice at 4 weeks but had no effect on lesion formation in p21-/- mice. CONCLUSIONS: Our findings provide genetic evidence that tranilast inhibits intimal hyperplasia via a p21-dependent pathway, an activity that may contribute to its efficacy in the prophylactic treatment of postangioplasty restenosis.

Animals↗
PubMed2002

Inhibitory effects of novel AP-1 decoy oligodeoxynucleotides on vascular smooth muscle cell proliferation in vitro and neointimal formation in vivo.

Excessive proliferation of vascular smooth muscle cells (VSMCs) and neointimal formation are critical steps in the pathogenesis of atherosclerosis and restenosis after percutaneous transluminal angioplasty. In this study, we investigated the hypothesis that the activator protein-1 (AP-1) plays an important role in neointimal formation after vascular injury. A circular dumbbell AP-1 decoy oligodeoxynucleotide (CDODN) was developed as a novel therapeutic strategy for restenosis after angioplasty. This CDODN was more stable than the conventional phosphorothioate linear decoy ODN (PSODN) and maintained structural integrity on exposure to exonuclease III or serum. Transfection with AP-1 decoy ODNs strongly inhibited VSMC proliferation and migration, as well as glucose- and serum-induced expression of PCNA and cyclin A genes. Administration of AP-1 decoy ODNs in vivo using the hemagglutinating virus of Japan (HVJ)-liposome method virtually abolished neointimal formation after balloon injury to the rat carotid artery. Compared with PSODN, CDODN was more effective in inhibiting the proliferation of VSMCs in vitro and neointimal formation in vivo. Our results collectively indicate that AP-1 activation is crucial for the mediation of VSMC proliferation in response to vascular injury. Moreover, the use of stable CDODN specific for AP-1 activity in combination with the highly effective HVJ-liposome method provides a novel potential therapeutic strategy for the prevention of restenosis after angioplasty in humans.

Angioplasty, Balloon↗
PubMed2002

Efp targets 14-3-3 sigma for proteolysis and promotes breast tumour growth.

Oestrogen exerts its influence on target organs through activating oestrogen receptors (ERs) and regulating downstream genes by means of their oestrogen-responsive elements. Efp, a target gene product of ER alpha, is a member of the RING-finger B-box coiled-coil (RBCC) motif family. Efp is predominantly expressed in various female organs as well as in breast cancers, and is thought to be essential for oestrogen-dependent cell proliferation and organ development Efp-disrupted mice display underdeveloped uteri and reduced oestrogen responsiveness. Here we show that Efp is a RING-finger-dependent ubiquitin ligase (E3) that targets proteolysis of 14-3-3 sigma, a negative cell cycle regulator that causes G2 arrest. We demonstrate that tumour growth of breast cancer MCF7 cells implanted in female athymic mice is reduced by treatment with antisense Efp oligonucleotide. Efp-overexpressing MCF7 cells in ovariectomized athymic mice generate tumours in the absence of oestrogen. Loss of Efp function in mouse embryonic fibroblasts results in an accumulation of 14-3-3 sigma, which is responsible for reduced cell growth. These data provide an insight into the cell-cycle machinery and tumorigenesis of breast cancer by identifying 14-3-3 sigma as a target for proteolysis by Efp, leading to cell proliferation.

14-3-3 Proteins↗
PubMed2002

Red wine polyphenols inhibit vascular smooth muscle cell migration through two distinct signaling pathways.

BACKGROUND: Red wine polyphenols (RWPs) have been shown to have an antiatherogenic activity mainly through antioxidative effects on LDL oxidation. Although vascular smooth muscle cell (SMC) migration is critical to atherosclerosis formation, the effect of RWPs on SMC migration has not been elucidated. In this study, we investigated whether RWPs could affect the migration of cultured SMCs stimulated by growth factors. METHODS AND RESULTS: RWP concentration dependently inhibited platelet-derived growth factor (PDGF)-BB-induced and serum-induced SMC migration in wounding assay and Boyden chamber assay. However, these inhibitory effects of RWPs were not seen in serum-stimulated vascular endothelial cell migration in either assay. Moreover, specific inhibitors of phosphatidylinositol-3' kinase (PI3K) and p38 mitogen-activated protein kinase (p38(MAPK)), but not of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), reduced PDGF-BB-induced SMC migration. To elucidate the signaling mechanism underlying the RWP effects, we investigated the effects of RWPs on the activity of PI3K and the phosphorylation of MAPK pathways in PDGF-BB-stimulated SMCs. RWPs inhibited the PI3K activity and p38(MAPK) phosphorylation, but not ERK1/2 phosphorylation, in a concentration-dependent manner. Moreover, the phosphorylation of MKK3/6, an upstream kinase of p38(MAPK), was also inhibited by RWP treatment in a concentration-dependent manner, suggesting that the inhibitory effect of RWPs on the p38(MAPK) pathway works upstream of MKK3/6. The concentration-effect relationship of RWPs necessary for the inhibition of PI3K and p38(MAPK) pathways was similar to that of cell migration assays. CONCLUSIONS: RWPs inhibit the SMC migration through the inhibition of 2 distinct signaling pathways and thus exert antiatherogenic actions.

Animals↗
PubMed2002

Effect of red wine polyphenols on vascular smooth muscle cell function--molecular mechanism of the 'French paradox'.

Red wine polyphenols (RWP) have been shown to have an anti-atherogenic activity mainly through anti-oxidative effects on low-density lipoprotein (LDL) oxidation. Though proliferation of vascular smooth muscle cells (VSMC) is critical to atherosclerosis formation, the effect of RWP on VSMC proliferation has not been elucidated. In this study, we investigated whether RWP, which extracted from red wine using column chromatography, could affect the 10% serum-stimulated VSMC proliferation. Treatment with RWP showed a potent inhibitory effect on the proliferation and DNA syntheses is in cultured rat VSMC. In contrast, the inhibitory effect of RWP on the proliferation of bovine vascular endothelial cells (EC) was only observed at much higher doses. Moreover, RWP significantly inhibited the proliferation and DNA synthesis of human VSMC but no human vascular EC in a dose-dependent manner. To elucidate the molecular mechanisms of these anti-proliferative effects of RWP on VSMC, but not on vascular EC, we investigated the effects of RWP on the cell cycle regulation. RWP downregulated the expression and promoter activity of cyclin A gene, one of cell cycle regulators. In addition, RWP inhibited the binding of nuclear proteins to the activating transcription factor (ATF) site in the cyclin A promoter, and downregulated the expression of transcription factors, cyclic AMP-responsive element binding protein (CREB) and ATF-1. In conclusion, these results demonstrate one possible finding that the anti-proliferative effect of RWP on VSMC may be associated with the downregulation of cyclin A gene expression through the inhibition of transcription factor expression.

Activating Transcription Factor 1↗
PubMed2002

Airway hyperresponsiveness in transgenic mice overexpressing platelet activating factor receptor is mediated by an atropine-sensitive pathway.

Platelet activating factor (PAF) is a potent mediator potentially involved in the pathogenesis of inflammatory disorders, including bronchial asthma. Recently, transgenic mice overexpressing the PAF receptor (PAFR) gene have been established, and exhibit bronchial hyperresponsiveness, one of the cardinal features of asthma. To elucidate the molecular and pathophysiologic mechanisms underlying PAF-associated bronchial hyperreactivity, we studied airway responsiveness to methacholine (MCh) and serotonin (5-hydroxytryptamine; 5-HT) in PAFR-transgenic mice. In addition, we examined the role of the muscarinic receptor in PAF-induced responses and the binding activities of the muscarinic receptor. The PAFR-transgenic mice exhibited hyperresponsiveness to MCh and PAF; however, no significant differences in 5-HT responsiveness were observed between the control and PAFR-transgenic mice. The administration of atropine significantly blocked PAF-induced responses in PAFR-transgenic mice. There were no differences between the two phenotypes in the binding activities of muscarinic receptor. Morphometric analyses demonstrated that PAFR overexpression did not affect airway structure. These findings suggest that the muscarinic pathway may have a key role in airway hyperresponsiveness associated with PAFR gene overexpression. More generally, PAFR-transgenic mice may provide appropriate models for study of the molecular mechanisms underlying PAF-associated diseases.

Animals↗
PubMed2002

Augmentation of immune cell activity against tumor cells by Rauwolfia radix.

In this study, we investigated the effect of Rauwolfia radix on heat shock protein (HSP) 70 expression and cytotoxicity against tumor cells in activated human T cells. When activated T cells were cultured with Rauwolfia radix for 18 h, HSP70 expression after heat shock was remarkably increased, and cytotoxicity against T98G tumor cells was augmented. Moreover, Rauwolfia radix also enhanced the cytotoxicity of heat shocked activated T cells against Molt-4 and T98G tumor cells. Secretions of interferon-gamma (IFN-gamma) and tumor necrosis alpha (TNF-alpha), due to Concanavalin A (Con A) stimulation, were increased by Rauwolfia radix in activated T cells. To investigate the antitumor effect in vivo, EL-4 tumor-bearing mice were administered with Rauwolfia radix in drinking water. The survival period of the Rauwolfia radix treatment group was significantly prolonged compared with that of the control group. Reserpine, the major active ingredient of Rauwolfia radix, also enhanced the cytotoxicity of activated T cells against Molt-4 and T98G tumor cells, and prolonged the survival period of EL-4 tumor-bearing mice. Taken together, our results suggest that Rauwolfia radix can enhance the activity of immune cells against tumor cells.

Animals↗
PubMed2002

A pivotal role of cytosolic phospholipase A(2) in bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is an interstitial disorder of the lung parenchyma whose mechanism is poorly understood. Potential mechanisms include the infiltration of inflammatory cells to the lungs and the generation of pro-inflammatory mediators. In particular, idiopathic pulmonary fibrosis is a progressive and fatal form of the disorder characterized by alveolar inflammation, fibroblast proliferation and collagen deposition. Here, we investigated the role of cytosolic phospholipase A(2) (cPLA(2)) in pulmonary fibrosis using cPLA(2)-null mutant mice, as cPLA(2) is a key enzyme in the generation of pro-inflammatory eicosanoids. Disruption of the gene encoding cPLA(2) (Pla2g4a) attenuated IPF and inflammation induced by bleomycin administration. Bleomycin-induced overproduction of thromboxanes and leukotrienes in lung was significantly reduced in cPLA(2)-null mice. Our data suggest that cPLA(2) has an important role in the pathogenesis of pulmonary fibrosis. The inhibition of cPLA(2)-initiated pathways might provide a novel therapeutic approach to pulmonary fibrosis, for which no pharmaceutical agents are currently available.

Animals↗