Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial dysfunction has been reported in obese subjects, but its mechanism has not been elucidated. We have therefore investigated 1) the possible relationship among BMI, waist-to-hip ratio (WHR), and endothelium-dependent vasodilation and 2) whether oxidative stress participates in endothelial dysfunction. We recruited 76 healthy subjects (50 men and 26 women aged 21-45 years) and measured their BMI (kg/m2), WHR, and insulin resistance (IR) estimated by the homeostasis model assessment (HOMA). Endothelium-dependent and -independent vasodilation were assessed by increasing doses of acetylcholine (ACh) (7.5, 15, and 30 pg x ml(-1) x min(-1)) and sodium nitroprusside (SNP) (0.8, 1.6, and 3.2 microg x ml(-1) x min(-1)) during saline and vitamin C coinfusion (24 mg/min). The effects of cyclooxygenase activity were evaluated by a dose-response curve to intrabrachial coinfusion of ACh and indomethacin (500 microg/min). Three different groups have been identified according to their BMI: group A (BMI <25), consisting of 10 men and 5 women; group B (BMI between 25 and 29), consisting of 16 men and 8 women; and group C (BMI > or =30), consisting of 24 men and 13 women. Obese subjects had significantly lower forearm blood flow (FBF) during ACh infusions (means +/- SD): 19.8 +/- 2.8, 10.8 +/- 2.7, and 6.5 +/- 1.8 ml x 100 ml(-1) tissue x min(-1) (P < 0.0001) for groups A, B, and C, respectively. SNP caused comparable increments in FBF in all groups. Regression analysis revealed a significant negative correlation between BMI (r = -0.676, P < 0.0001), WHR (r = -0.631, P < 0.0001), fasting insulin (r = -0.695, P < 0.0001), HOMA-IR (r = -0.633, P < 0.0001), and percent peak increase in FBF during ACh infusion. In obese subjects, both vitamin C and indomethacin increased the impaired vasodilating response to ACh, whereas the SNP effect was unchanged. In conclusion, in obese subjects, ACh-stimulated vasodilation is blunted, and the increase in FBF is inversely related to BMI, WHR, fasting insulin, and HOMA-IR. The effects of both vitamin C and indomethacin on impaired ACh-stimulated vasodilation support the hypothesis that oxidative stress contributes to endothelial dysfunction in human obesity.
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PMID:Obesity and body fat distribution induce endothelial dysfunction by oxidative stress: protective effect of vitamin C. 1114 82

We investigated the role of insulin and glucose in the pathophysiology of hypertension associated with obesity. The comparative effects of an oral glucose load and of an L-arginine infusion on plasma glucose, plasma insulin and blood pressures (BP) were assessed in lean normotensive and in obese hypertensive males. Oral glucose (75 g in 1-2 min) induced a small but significant lowering of BP in lean normotensives, but failed to modify BP in obese hypertensives. L-arginine infusion (30 min, 500 mg/kg total dose) reduced BP; significantly greater reductions in systolic and diastolic BP were observed in obese hypertensives than in the control group. Both oral glucose and L-arginine induced greater increases in plasma insulin in obese hypertensives than in lean normotensives. Endothelial dysfunction which accompanies the insulin resistant state of obesity, glucose intolerance and hypertension, may account for the different BP effects induced by glucose and L-arginine in obese hypertensives and lean normotensives.
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PMID:Differential blood pressure effects of oral glucose and intravenous L-arginine in healthy lean normotensive and obese hypertensive subjects. 1198 11

Anorectic drugs are widely used for the treatment of obesity. They are thought to decrease appetite through their effects on catecholamine or 5-hydroxytryptamine (5-HT) levels in the brain. Their use has been associated with epidemics of pulmonary hypertension and the development of valvular heart disease, hypertension, stroke and digital or mesenteric ischemia. Understanding the mechanism of the cardiovascular toxicity of anorectic drugs is important because of the modern epidemic of obesity and the resulting plethora of new anorexigens, many of which share similar mechanisms with those that have previously caused cardiovascular disease. In addition, the mechanism by which anorexigens cause vascular disease has relevance to the etiology and treatment of pulmonary and systemic hypertension. Recent discoveries have clarified how the anorexigens cause vasoconstriction and hypertension. Most anorexigens directly inhibit voltage-gated K+ (KV) channels in vascular smooth muscle cells (SMCs). This reduced K+ efflux leads to depolarization, the opening of voltage-sensitive Ca2+ channels, an increase in intracellular Ca2+ and vasoconstriction. Endothelial dysfunction appears to be a predisposing factor for the development of anorectic-induced vascular complications. Vasoconstriction is weak at clinically relevant doses of anorectic drugs. However, when nitric oxide synthase is inhibited, vasoconstriction is significantly enhanced. Anorexigens are the only drugs in widespread clinical use that have KV-channel-blocking properties and it is probable that much of their cardiovascular toxicity relates to this mechanism. Investigators need to examine new anorexigens and other therapeutic molecules for inhibitory effects on KV channels, as this effect may be a marker of drugs that will elicit vascular complications.
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PMID:Anorectic drugs and vascular disease: the role of voltage-gated K+ channels. 1237 23

Obese women with polycystic ovary syndrome (PCOS) exhibit impaired endothelial function, which is strongly and directly correlated with both testosterone levels and insulin resistance. Endothelial dysfunction is considered a potent risk factor for macrovascular disease. Because troglitazone (Tgz) improves both hormonal profiles and insulin sensitivity, we tested whether Tgz treatment ameliorates endothelial function in these patients. We studied leg blood flow (LBF) responses to graded intrafemoral artery infusion of the endothelium-dependent vasodilator methacholine chloride (MCh) and to a 4-h hyperinsulinemic euglycemic clamp (120 mU/m(2) x min) in 10 PCOS, before and after 3 months treatment with Tgz (600 mg/d). A group of 13 obese women (OBW) matched for age, weight, body fat (>40% in both groups), blood pressure, and total cholesterol served as controls. PCOS patients exhibited elevated free testosterone (fT) and triglycerides (TG) and lower high density lipoprotein cholesterol levels compared with OBW [14.0 +/- 1.0 vs. 3.7 +/- 0.6 pmol/liter (P < 0.0001), 1.60 +/- 0.28 vs. 0.94 +/- 0.09 mmol/liter (P < 0.02), and 0.91 +/- 0.04 vs. 1.1 +/- 0.04 mmol/liter (P < 0.005), respectively]. Tgz treatment reduced fT levels, but did not improve the TG and high density lipoprotein profile [to 9.7 +/- 2.8 pmol/liter (P < 0.007), 1.49 +/- 0.34 mmol/liter (P = NS), and 0.93 +/- 0.07 mmol/liter (P = NS), respectively]. Basal LBF was unchanged after Tgz. In PCOS compared with OBW, insulin stimulated glucose disposal (52.7 +/- 6.6 vs. 85.5 +/- 4.4 micromol/kg fat-free mass x min; P < 0.0005) and vasodilation (increase in LBF, 22 +/- 14% vs. 59 +/- 15%; P < 0.05) were significantly improved after Tgz treatment to 68.8 +/- 7.2 micromol/kg fat-free mass x min (P < 0.0001) and 101 +/- 48% (P < 0.03), respectively. The increase in LBF in response to MCh in PCOS was markedly more pronounced after treatment (P < 0.01, by ANOVA) and was similar to that observed in OBW. Before Tgz treatment, maximal LBF increments in response to MCh were 130 +/- 25% and 233 +/- 29% in PCOS and OBW, respectively (P < 0.01). After Tgz treatment, PCOS values improved, achieving increments similar to those in OBW (245 +/- 45%; P < 0.04). Tgz treatment in PCOS improves both hormonal and metabolic features. These modifications are associated with improvement of endothelial function, suggesting that Tgz could be a useful tool to reduce the risk of macrovascular disease in women with PCOS and perhaps in other insulin-resistant syndromes.
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PMID:Troglitazone therapy improves endothelial function to near normal levels in women with polycystic ovary syndrome. 1257 83

In nondiabetic individuals, a poor response to an endothelium-dependent vasodilator in coronary vessels has been shown to increase the likelihood of a future cardiovascular event. Such prospective data are not as yet available in patients with type 1 or type 2 diabetes. However, consistent with the greatly increased cardiovascular risk in these patients, endothelial dysfunction has been almost universally found to characterize patients with type 2 diabetes particularly. Endothelial dysfunction frequently coexists with features of insulin resistance, such as the presence of small dense low-density lipoprotein (LDL) particles even in nondiabetic individuals. This association is independent of obesity and other causes of endothelial dysfunction, such as LDL cholesterol, hypertension, and smoking. In patients with type 1 diabetes, endothelial dysfunction has been found in approximately half of the studies. In some but not all studies, endothelial dysfunction has been especially severe in patients with poor glycemic control. Reversal or amelioration of endothelial dysfunction has been documented by many commonly used therapeutic agents such as successful insulin therapy, fibrates, and angiotensin-converting enzyme inhibitors, but also with some but not all agents that act as antioxidants. Long-term studies addressing the prognostic significance of endothelial dysfunction and its reversal are urgently needed to determine whether measurement of endothelial function could be used to identify individuals at risk better than can be done at present using classic risk factor assessment among patients with type 2 diabetes especially.
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PMID:Endothelial dysfunction in human diabetes. 1264 20

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.
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PMID:Association of hypoadiponectinemia with impaired vasoreactivity. 1286 Aug 35

Endothelial dysfunction is a critical factor in the development of vascular disease in patients with diabetes mellitus. Maintenance of the vascular tone and luminal diameter of a blood vessel is dependent on the net balance of vasoconstrictor and vasodilator forces. In both diabetes and obesity, vascular reactivity is abnormal. After ischemia, carbon dioxide challenge, thermal challenge, or exercise, individuals with diabetes do not exhibit the increase in blood flow or vasodilation observed in persons without diabetes. The mechanisms involved in abnormal reactivity may include both the endothelium and vascular smooth muscle. Major vasodilator factors that act on vascular smooth muscle cells are nitric oxide, prostacyclin, and hyperpolarizing factor. The main vasoconstrictors are endothelin, angiotensin II, norepinephrine, serotonin, and thromboxane A(2). In patients with diabetes, there is an increase in vasoconstrictors and a decrease in vasodilators. Thiazolidinediones (TZDs) improve vasodilative responses, which may be of importance in the treatment of vascular disease. The TZDs have anti-inflammatory effects and suppress free fatty acids and reactive oxygen species at the endothelial level, which may contribute to the improved vascular reactivity observed in patients treated with these agents. In addition, these effects of TZDs may have implications for reducing the incidence and severity of atherosclerosis in the long term.
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PMID:Vascular reactivity and thiazolidinediones. 1467 71

Endothelial dysfunction has been suggested to play an important role in the development of obesity-induced hypertension. Because endothelin release increases in response to endothelial damage, we examined whether endothelin-1 contributes to increased arterial pressure in a model of visceral obesity produced by feeding Sprague-Dawley rats a high-fat (HF) diet (40% fat w/w, n=6) for 12 months. Arterial and venous catheters were implanted for measurement of mean arterial pressure (MAP) and heart rate (HR) 24 hours per day and intravenous infusions. After a 5-day control period, rats were infused with the selective endothelin-1 type A receptor (ET-A) blocker ABT-627 (2.5 mg/kg per day, IV) for 9 days, followed by a recovery period. Rats fed a standard chow (normal fat, or NF, group: n=6) for 12 months were also infused with ET-A blocker and were used as controls. Compared with NF rats, HF rats had higher MAP (113+/-4 versus 98+/-2 mm Hg), increased visceral fat (18.7+/-2.0 versus 10.8+/-1.4 g), and 3.2-fold increase in plasma leptin despite similar total body weight gain. Long-term ET-A blockade markedly reduced MAP in HF (-14+/-3 mm Hg) and NF (-14+/-2 mm Hg), but it had no effect on HR, GFR, or PRA. These results indicate that a long-term HF diet may cause visceral obesity and increased MAP, even in the absence of major changes in total body weight. Endothelin-1 appears to play an important role in the maintenance of arterial pressure in rats fed HF and NF diets, but it does not appear to contribute to increased MAP in this model of diet-induced hypertension.
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PMID:Role of endothelin-1 in blood pressure regulation in a rat model of visceral obesity and hypertension. 1470 64

Endothelial dysfunction reflects an imbalance of vasodilators and vasoconstrictors. Endogenous endothelin activity seems to be increased in human obesity and type 2 diabetes, and cellular studies suggest that this factor may itself reduce bioavailable nitric oxide (NO). We studied 20 lean, 20 obese, and 14 type 2 diabetic individuals under three protocols, measuring leg vascular responses to intra-arterial infusions of NG-monomethyl-l-arginine (l-NMMA; an inhibitor of NO synthase) alone or in combination with BQ123 (an antagonist of type A endothelin receptors) or phentolamine (used as a control vasodilator). NO synthase inhibition alone (study 1) produced an approximately 40% increase in leg vascular resistance (LVR) in all three participant groups, which was not statistically different across groups (increase in LVR: lean, 135 +/- 28; obese, 140 +/- 32; type 2 diabetic, 184 +/- 51 units; NS). By design, BQ123 at the infused rate of 3 micromol/min produced equivalent approximately 35% reductions in LVR across groups. The subsequent addition of l-NMMA produced a greater increase in LVR among obese participants than lean or type 2 diabetic participants (study 2: lean, 182 +/- 48; obese, 311 +/- 66; type 2 diabetic, 186 +/- 40; P = 0.07). Compared with study 1, the effect of l-NMMA was magnified by BQ123 in obese participants but not in lean or type 2 diabetic participants (P = 0.005, study 1 vs. 2; P = 0.03 for group effect). Phentolamine (75 mg/min) produced vasodilation in obese participants comparable to that seen with BQ123 but failed to augment the L-NMMA response. Endothelin antagonism unmasks or augments NO synthesis capacity in obese but not type 2 diabetic participants. This suggests that impaired NO bioavailability as a result of endogenous endothelin may contribute to endothelial dysfunction in obesity, in addition to direct vasoconstrictor effects of endothelin. In contrast, endothelin antagonism alone is insufficient to restore impaired NO bioavailability in diabetes.
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PMID:Interactions between endothelin and nitric oxide in the regulation of vascular tone in obesity and diabetes. 1527 86

Vascular integrity in the healthy endothelium is maintained through the release of a variety of paracrine factors such as NO (nitric oxide). Endothelial dysfunction, characterized by reduced NO bioavailability, is associated with obesity, insulin resistance and Type II diabetes. Insulin has been demonstrated to have direct effects on the endothelium to increase NO bioavailability. Therefore altered insulin signalling in the endothelium represents a candidate mechanism underlying the association between insulin resistance and endothelial dysfunction. In recent years, it has become apparent that insulin sensitivity is regulated by the adipocytokines, a group of bioactive proteins secreted by adipose tissue. Secretion of adipocytokines is altered in obese individuals and there is increasing evidence that the adipocytokines have direct effects on the vascular endothelium. A number of current antidiabetic strategies have been demonstrated to have beneficial effects on endothelial function and to alter adipocytokine concentrations in addition to their effects on glucose homoeostasis. In this review we will explore the notion that the association between insulin resistance and endothelial dysfunction is accounted for by adipocytokine action on the endothelium. In addition, we examine the effects of weight loss, exercise and antidiabetic drugs on adipocytokine availability and endothelial function.
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PMID:The role of insulin and the adipocytokines in regulation of vascular endothelial function. 1532 98


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