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Biomedical subjects

Toshio Ogihara

Publications and source records attributed to Toshio Ogihara.

At least 19 recordsLinked to original sources
PubMed2003

Serum uric acid and plasma norepinephrine concentrations predict subsequent weight gain and blood pressure elevation.

It has been reported that hypertension and obesity often coexist with hyperuricemia. To clarify the relations between serum uric acid, plasma norepinephrine, and insulin or leptin levels in subjects with weight gain-induced blood pressure elevation, we conducted the present longitudinal study. In 433 young, nonobese, normotensive men, body mass index, blood pressure, and levels of serum uric acid, fasting plasma norepinephrine, insulin, and leptin were measured every year for 5 years. Subjects were stratified by significant weight gain and/or blood pressure elevation (>10% in body mass index or mean blood pressure) for 5 years. At entry, blood pressure, uric acid, and norepinephrine values in subjects with blood pressure elevation were greater than in those without it, although body mass index, insulin, and leptin were similar. At entry, body mass index, blood pressure, uric acid, and norepinephrine in subjects with weight gain were greater than in those without weight gain. The increases in body mass index, mean blood pressure, uric acid, norepinephrine, insulin, and leptin for 5 years were greater in subjects with blood pressure elevation and/or weight gain than in subjects without, and those increases were greatest in subjects with weight gain whose blood pressure was elevated. By multiple regression analysis, basal mean blood pressure, norepinephrine, and uric acid were significant determinant factors of changes in mean blood pressure over 5 years, and basal body mass index, norepinephrine, and uric acid were significant determinant factors of changes in body mass index. These results demonstrate that serum uric acid and plasma norepinephrine concentrations predict subsequent weight gain and blood pressure elevation.

Adult↗
PubMed2003

Eicosapentaenoic acid protects endothelial cells against anoikis through restoration of cFLIP.

Dietary supplementation with eicosapentaenoic acid (EPA) improves the prognosis of chronic inflammatory diseases, including atherosclerosis. The mechanism underlying these beneficial effects, however, remains to be elucidated. Here we show that EPA protects endothelial cells from anoikis through upregulation of the cellular FLICE (Fas-associating protein with death domain-like interleukin-1-converting enzyme)-inhibitory protein (cFLIP), an endogenous inhibitor of caspase-8. EPA-induced upregulation of cFLIP expression was partially suppressed by the phosphatidylinositol-3-kinase inhibitor wortmannin. Conversely, treatment with insulinlike growth factor-1 (IGF-1), an activator of phosphatidylinositol-3-kinase/Akt signaling, or infection with an adenoviral construct expressing the constitutively active Akt gene induced upregulation of cFLIP expression. In addition, pretreatment of endothelial cells with either EPA or IGF-1 protected them from anoikis, suggesting that EPA-induced protection against anoikis is partially mediated through activation of Akt. On the other hand, when endothelial cells were already detached, treatment of these cells with EPA but not with IGF-1 protected them against anoikis. Importantly, EPA restored cFLIP expression without activating Akt signaling in detached endothelial cells, whereas IGF-1 had no effect. Additionally, exogenously restored expression of cFLIP by the tetracycline-regulated adenovirus system protected endothelial cells against anoikis. Furthermore, EPA was protective against the loss of endothelium in an organ culture of rat aortas. These findings suggest that EPA protects against endothelial cell anoikis through restoration of cFLIP expression, which might contribute to the mechanism underlying the beneficial effects of EPA in patients with hypertension.

Anoikis↗
PubMed2003

Association of hypoadiponectinemia with impaired vasoreactivity.

Endothelial dysfunction is a crucial feature in the evolution of atherosclerosis. Adiponectin is an adipocyte-specific plasma protein with antiatherogenic and antidiabetic properties. In the present study, we investigated the relation between adiponectin and endothelium-dependent vasodilation. We analyzed endothelial function in 202 hypertensive patients, including those who were not taking any medication. Forearm blood flow was measured by strain-gauge plethysmography. Plasma adiponectin level was highly correlated with the vasodilator response to reactive hyperemia in the total (r=0.257, P<0.001) and no-medication (r=0.296, P=0.026) groups but not with nitroglycerin-induced hyperemia, indicating that adiponectin affected endothelium-dependent vasodilation. Multiple regression analysis of data from all hypertensive patients revealed that plasma adiponectin level was independently correlated with the vasodilator response to reactive hyperemia. Vascular reactivity was also analyzed in aortic rings from adiponectin-knockout (KO) and wild-type (WT) mice. Adiponectin-KO mice showed obesity, hyperglycemia, and hypertension compared with WT mice after 4 weeks on an atherogenic diet. Endothelium-dependent vasodilation in response to acetylcholine was significantly reduced in adiponectin-KO mice compared with WT mice, although no significant difference was observed in endothelium-independent vasodilation in response to sodium nitroprusside. Our observations suggest that hypoadiponectinemia is associated with impaired endothelium-dependent vasorelaxation and that the measurement of plasma adiponectin level might be helpful as a marker of endothelial dysfunction.

Acetylcholine↗
PubMed2003

Association of methylenetetrahydrofolate reductase gene polymorphism with carotid atherosclerosis depending on smoking status in a Japanese general population.

BACKGROUND AND PURPOSE: The association of the methylenetetrahydrofolate reductase gene (MTHFR) with carotid atherosclerosis remains inconsistent. This may be due to small sample size and inappropriate analysis. We investigated the association of C677T/MTHFR with blood pressure and carotid atherosclerosis in a Japanese general population. METHODS: Subjects (30 to 89 years of age; 1693 women, 1554 men) who gave informed consent were randomly selected from a general population in Suita, Japan. MTHFR genotypes were determined by TaqMan polymerase chain reaction. Carotid atherosclerosis was evaluated by high-resolution ultrasonography with atherosclerotic indexes of intimal-medial thickness (IMT), maximum IMT in the common carotid artery (CCA), plaque score, and stenosis (>50%). RESULTS: Age-adjusted diastolic blood pressure was significantly higher in women with the TT genotype than in those with the CC genotype. In a recessive model (CC+CT versus TT), all adjusted odds ratios for hypertension and >50% stenosis in women were 1.42 and 3.42 (95% confidence intervals, 1.01 to 1.99 and 1.23 to 9.53), respectively. In women, maximum IMT in CCA for smokers with the TT genotype was significantly higher than for smokers with the CC genotype and nonsmokers with the TT genotype (P<0.05). CONCLUSIONS: Our study suggests that the MTHFR TT genotype is a risk factor for hypertension and carotid stenosis in women. Significant interactions between C677T/MTHFR and smoking on maximum IMT in CCA were observed in women but not in men. Smoking cessation for subjects with the TT genotype is important in the prevention of cerebrovascular disease.

Adult↗
PubMed2003

Angiogenic property of hepatocyte growth factor is dependent on upregulation of essential transcription factor for angiogenesis, ets-1.

BACKGROUND: Although hepatocyte growth factor (HGF) is an angiogenic growth factor, it is still unclear how it exerts its angiogenic effects. Thus, we focused on the role of an essential transcription factor for angiogenesis, ets-1. In this study, we addressed the following specific questions: (1) what genes responsible for angiogenesis can be regulated by HGF and (2) whether upregulation of gene expression for angiogenesis is dependent on ets-1. METHODS AND RESULTS: In human endothelial cells, HGF significantly stimulated the matrix-degrading pathway, such as the production of matrix metalloprotease-1 (MMP-1) through its specific receptor, c-met. In addition, HGF also significantly increased HGF itself and its specific receptor, c-met. Moreover, HGF significantly increased the transcription activity and mRNA expression of ets-1 in a time-dependent manner. Importantly, transfection of antisense ets-1 oligodeoxynucleotides (ODN) resulted in a significant reduction in MMP-1, HGF and c-met. Interestingly, HGF also stimulated ets-1 mRNA in vascular smooth muscle cells, similar to endothelial cells. Of importance, transfection of antisense ets-1 ODN resulted in a significant decrease in vascular endothelial growth factor (VEGF) and HGF expression, whereas HGF stimulated both HGF and VEGF expression. Moreover, in vivo transfection of ets-1 antisense ODN resulted in an inhibition of angiogenesis induced by the HGF gene in a rat ischemic hindlimb model. CONCLUSIONS: Here, we demonstrated that HGF stimulated the expression of MMP-1, VEGF, HGF itself, and c-met in human endothelial cells and vascular smooth muscle cells. Upregulation of angiogenesis-related genes was largely dependent on the induction of ets, especially ets-1. These data provide new information about the mechanisms of angiogenesis.

Animals↗
PubMed2003

Upregulation of cAMP is a new functional signal pathway of Klotho in endothelial cells.

We measured angiotensin I-converting enzyme (ACE) activity in a human endothelial cell to characterize the intracellular signal pathways of Klotho. COS-1 cells transfected with naked mouse membrane-form klotho plasmid DNA (pCAGGS-klotho) translated proper Klotho protein. This translated Klotho protein was secreted into the culture medium. Furthermore, ACE activity in human umbilical vein endothelial cells (HUVEC) was upregulated when HUVEC were co-cultured with COS-1 cells that were pre-transfected with pCAGGS-klotho. The conditioned medium from COS-1 cells pre-transfected with pCAGGS-klotho also dose-dependently upregulated ACE in HUVEC. In addition, the conditioned medium induced time- and dose-dependent enhancement of cAMP production in HUVEC. Rp-cAMP, an inhibitor of cAMP-dependent protein kinase A (PKA), inhibited the upregulation of ACE by Klotho protein. Our results suggest that mouse membrane-form Klotho protein acts as a humoral factor to increase ACE activity in HUVEC via a cAMP-PKA-dependent pathway. These findings may provide a new insight into the mechanism of Klotho protein.

Animals↗
PubMed2003

Enhanced angiogenesis and improvement of neuropathy by cotransfection of human hepatocyte growth factor and prostacyclin synthase gene.

The current therapeutic angiogenesis strategy to treat ischemic disease by using angiogenic growth factors has been limited to use of a single gene. However, as vasodilator substances such as prostacyclin are widely used for the treatment of peripheral arterial disease, it might be useful to combine angiogenesis with vasodilation of new vessels. In a mouse hind limb ischemia model, cotransfection of the hepatocyte growth factor (HGF) gene with the prostacyclin synthase gene demonstrated a further increase in blood flow and capillary density compared with a single gene. Even in the rabbit ischemia model, cotransfection of HGF plasmid with the prostacyclin synthase gene demonstrated a further increase in angiogenic activity compared with HGF alone. Because peripheral neuropathy due to diabetes is common for significant morbidity, we examined the hypothesis that experimental diabetic neuropathy can be reversed by HGF and prostacyclin synthase genes. Severe peripheral neuropathy, characterized by significant slowing of nerve conduction velocity compared with nondiabetic control animals, was ameliorated. Overall, cotransfection of the prostacyclin synthase and HGF genes is more effective than single-gene transfection to stimulate angiogenesis, and it significantly improved neuropathy. These data provide important information relating to the clinical application of therapeutic angiogenesis to treat peripheral arterial disease.

Animals↗
PubMed2003

Improvement of endothelial dysfunction by angiotensin II blockade accompanied by induction of vascular hepatocyte growth factor system in diabetic spontaneously hypertensive rats.

Hepatocyte growth factor (HGF) is a unique growth factor with many protective functions. Previously, we demonstrated that HGF stimulated growth of endothelial cells without replication of vascular smooth muscle cells (VSMC) and that angiotensin (Ang) II significantly decreased local HGF production in VSMC. Moreover, we also reported that high glucose significantly decreased local vascular HGF production. Therefore, we examined effects of Ang II blockade on vascular HGF expression and endothelial injury in diabetic hypertensive rats. An angiotensin-converting enzyme inhibitor (quinapril) and an Ang II type 1 receptor antagonist (GA-0113) or vehicle was administrated to diabetic spontaneously hypertensive rats (SHR-DM), in whom diabetes was induced by streptozotocin. Endothelial function was evaluated by the vasodilator response to acetylcholine, and the expression of vascular HGF and its receptor, c-met, was examined by immunohistochemistry. Both quinapril and GA-0113 significantly improved the vasodilator response to acetylcholine ( P < 0.01), while vehicle did not as compared to untreated normotensive Wistar-Kyoto rats (WKY). We next examined the effects of Ang II blockade on vascular HGF expression in SHR-DM. Importantly, the vascular HGF level was markedly decreased in SHR-DM as compared to WKY, while Ang II blockade by quinapril or GA-0113 significantly increased positive staining for HGF in SHR-DM. Similarly, staining of its specific receptor, c-met, was less in the blood vessels of SHR-DM as compared to WKY. In contrast, Ang II blockade also significantly increased c-met production in SHR-DM. The present data demonstrated the improvement of endothelial dysfunction by Ang II blockade in SHR-SM, accompanied by an increase in vascular HGF and c-met.

Acetylcholine↗
PubMed2003

Role of endothelin-1 induced by insulin in the regulation of vascular cell growth.

Insulin is not only a growth factor for vascular cells, but also an inducer of other vasoactive substances such as endothelin-1 (ET-1) in vascular cells. The aim of the present study was to assess the role of endothelial cells (EC) in insulin mediated vascular smooth muscle cell (VSMC) proliferation. Cultured human aortic EC and VSMC were separately incubated. EC were stimulated with insulin (0 to 1000 microU/mL) for 24 h, in the presence or absence of anti-insulin-growth factor-1 (anti-IGF-1) receptor antibody (alphaIR(3)) or a nonselective ET-1 receptor antagonist (TAK044). Cell proliferation was measured by determining (3)H-thymidine uptake. Although 10 microU/mL insulin did not affect ET-1 production in the EC culture medium, a higher concentration of insulin stimulated it. Production of ET-1 in EC was activated by insulin via the IGF-1 receptor, inasmuch as alphaIR(3) blocked insulin mediated upregulation of ET-1. There was no significant difference in (3)H-thymidine incorporation in the presence of insulin (up to 1000 microU/mL) or TAK044. Culture medium from EC stimulated with insulin enhanced VSMC proliferation, which was almost totally suppressed by TAK044. Insulin induced VSMC growth dose dependently when VSMC were cultured alone. In contrast, insulin at concentrations of 100 microU/mL or lower failed to stimulate growth of co-cultured VSMC, but only at 330 microU/mL or higher concentrations stimulated VSMC growth in this system. Of interest, VSMC proliferation was greatest when L-NAME was added and co-cultured with EC. In summary, a severely hyperinsulinemic state may regulate VSMC and EC proliferation via activation of vasoactive substances such as ET-1 and nitric oxide induced by insulin.

Aorta↗
PubMed2003

High-level expression of interleukin-4 following electroporation-mediated gene transfer accelerates Type 1 diabetes in NOD mice.

Nonobese diabetic (NOD) mice develop T cell-dependent autoimmune disease. Administration of interleukin-4 (IL-4), one of the T helper 2 (Th2) cytokines, is reported to prevent either insulitis or diabetes or both in NOD mice. We examined the effect of transferring an IL-4-expressing plasmid vector into muscle by in vivo electroporation on the progression of diabetes in NOD mice. Plasmid DNA expressing murine IL-4 (pCAGGS-IL-4) was introduced into the muscles of 4- and 6-week-old female NOD mice using an in vivo electroporation technique we developed previously. The serum IL-4 levels reached 2000-8000 pg/ml 3 days after the delivery of pCAGGS-IL-4 and remained detectable (>5 pg/ml) for over 4 weeks. In contrast to the previous reports, 88% of the mice treated with pCAGGS-IL-4 developed overt diabetes by 30 weeks of age, while only 25% of nontreated mice and 19% of the mice treated with control pCAGGS developed overt diabetes by then (p<0.01). Therefore, highly expressed IL-4 introduced by in vivo electroporation may have caused a Th1 shift, resulting in the promotion of diabetes in NOD mice. The high serum concentration of cytokines attained by our method is likely to unveil previously unknown cytokine functions.

Animals↗
PubMed2003

Association of I27L polymorphism of hepatocyte nuclear factor-1 alpha gene with high-density lipoprotein cholesterol level.

The serum level of high-density lipoprotein cholesterol (HDL-c), which protects against the development of atherosclerosis, is under genetic control. However, the genetic components responsible for the serum HDL-c level are yet to be determined. A recent knockout mouse study demonstrated that hepatocyte nuclear factor-1 alpha (HNF-1 alpha) is an essential transcriptional regulator of HDL-c metabolism. In this study, the association of an HNF-1 alpha gene polymorphism, isoleucine (Ile) 27 leucine (Leu), with lipid parameters, in particular with serum HDL-c level, was studied in 356 unrelated Japanese men. Though no significant difference was observed in total cholesterol and triglyceride levels among the three genotypes, the serum HDL-c level was significantly associated with the genotype (P < 0.01, trend test). Subjects with the Ile/Ile genotype had low serum HDL-c levels, and those with the Leu/Leu genotype had high serum HDL-c levels. These results demonstrate that the HNF-1 alpha gene locus is associated with serum HDL-c level and suggest that the Ile27 allele is a risk marker for atherosclerosis.

Adult↗
PubMed2003

Intravenous nicorandil in conjunction with coronary reperfusion therapy is associated with better clinical and functional outcomes in patients with acute myocardial infarction.

The aim of this retrospective study was to assess whether intravenous nicorandil, a hybrid of NO and a KATP channel opener, in conjunction with percutaneous coronary intervention (PCI) improves the long-term prognosis in patients with acute myocardial infarction (AMI). Intravenous nicorandil has already been shown to improve the in-hospital prognosis of patients with anterior AMI. The study population consisted of 272 patients with a reperfused AMI who were admitted during a similar time interval, before (control; n=114) and after nicorandil treatment (n=158). In the nicorandil group, a 4 mg bolus injection was given, followed by 6 mg/h infusion for 24 h and then oral nicorandil at 15 mg/day for at least 1 month. In the patients with an anterior AMI, left ventricular (LV) function was better and the frequency of LV remodeling was lower after 3 months in the nicorandil group; however, in those with a non-anterior AMI, there were no differences in functional outcome and the frequency of LV remodeling between the 2 groups. The frequency of cardiac events was significantly lower in the nicorandil group, and the use of nicorandil was derived as a potential factor related to freedom from cardiac events (p<0.01, odds ratio = 0.27). Nicorandil treatment was associated with better myocardial perfusion and a better functional and clinical outcome than PCI alone, and this beneficial effect was maintained for a long time, particularly in patients with anterior AMI.

Aged↗
PubMed2003

Lack of association between angiotensin II type 1 receptor gene polymorphism and hypertension in Japanese.

Angiotensin II type 1 (AT1) receptor mediates the vasoconstriction and growth-promoting effect of angiotensin II in humans. It has been reported that a polymorphism of the AT1 receptor gene (an A/C transversion at position 1166; A1166C) may be associated with essential hypertension (HT). However, several conflicting results have also been reported. Therefore, we conducted an association study between A1166C variants of the AT1 receptor gene and hypertension in the Japanese population. We genotyped this variant in 3,918 subjects (1,492 hypertensive subjects and 2,426 normotensive subjects) recruited from the Suita study. In subjects not receiving antihypertensive medication, the influence of the genotype on blood pressure values adjusted for clinical covariates was analyzed. The genotype distribution did not differ between hypertensive and normotensive subjects in either men (frequency of the C allele: 8.1% vs. 7.8%, p=0.74) or women (8.1% vs. 7.7%, p=0.60). There were no significant differences in systolic blood pressure, diastolic blood pressure, or pulse pressure among the three genotypes in either men or women who had not received hypertensive medication. Our data suggest that the A1166C polymorphism of AT1 receptor is unlikely to influence blood pressure status in the Japanese population.

Aged↗
PubMed2003

A/C1166 gene polymorphism of the angiotensin II type 1 receptor (AT1) and ambulatory blood pressure: the Ohasama Study.

We previously investigated the relation between hypertension and each of three major genetic polymorphisms in the renin-angiotensin (AGT)-aldosterone system (R-A-A), AGT M235T, angiotensin convert enzyme (ACE) I/D, and CYP11B2 -344C/T, by means of ambulatory blood pressure (ABP) monitoring in a general Japanese population (the Ohasama Study). A/C1166 gene polymorphism in the 3' untranslated region of the angiotensin II type 1 receptor (AT1) gene is the final remaining major target in R-A-A to be examined in the Ohasama Study population. In the present study, the AT1 A/C1166 polymorphism was genotyped by the TaqMan polymerase chain reaction (PCR) method or restriction fragment length polymorphism (RFLP) in 802 Japanese subjects aged 40 and over, who were previously genotyped for the AGT M235T, ACE D/I, CYP11B2 -344C/T polymorphisms. The AA genotype, AC genotype, and CC genotype were present in 678 (84.5%), 121 (15.1%), and 3 (0.4%) of subjects, respectively. Since the frequency of the C allele was quite low (0.079), the genotypes were classified according to the presence or absence of the C allele. Although daytime blood pressure (BP) was higher in subjects with the C allele, the difference was not statistically significant after adjusting for age, gender, body mass index, and smoking status. No significant difference was noted in the prevalence of cardiovascular diseases or nocturnal BP decline between the two groups. These results indicated that AT1 A/C1166 polymorphism was not associated with any clinical parameters associated with hypertension or atherosclerosis in the Japanese population.

Aged↗
PubMed2003

Azelnidipine and amlodipine: a comparison of their pharmacokinetics and effects on ambulatory blood pressure.

We objected: 1) To compare the effects of azelnidipine and amlodipine on 24-h blood pressure; 2) To monitor the plasma concentration vs. the time profile in order to assess the association between pharmacokinetics and hypotensive activity after administration of either drug for 6 weeks. Blood pressure and pulse rate were measured by 24-h monitoring with a portable automatic monitor in a randomized double-blind study of 46 patients with essential hypertension. Azelnidipine 16 mg (23 patients) or amlodipine 5 mg (23 patients) was administered once daily for 6 weeks. Pharmacokinetics were analyzed after the last dose was taken. Both drugs showed similar effects on the office blood pressure and pulse rate. During 24-h monitoring, both drugs caused a decrease in systolic blood pressure of 13 mmHg and had a similar hypotensive profile during the daytime period (07:00-21:30). The pulse rate decreased by 2 beats/min in the azelnidipine group, whereas it significantly increased by 4 beats/min in the amlodipine group. Similar trends in the blood pressure and pulse rate were observed during the nighttime (22:00-6:30) and over 24 h. Excessive blood pressure reduction during the nighttime was not seen in either group. The pharmacokinetic results indicated that the plasma half-life (t1/2) of amlodipine was 38.5 +/- 19.8 h and that of azelnidipine was 8.68 +/- 1.33 h. Despite this difference in pharmacokinetics, the hypotensive effects of amlodipine and azelnidipine were similar throughout the 24-h administration period.

Amlodipine↗