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At least 1,783 records · Page 99Linked to original sources
PubMed1998

L-2-Oxothiazolidine-4-carboxylic acid reverses endothelial dysfunction in patients with coronary artery disease.

The effective action of endothelium-derived nitric oxide (EDNO) is impaired in patients with atherosclerosis. This impairment has been attributed in part to increased vascular oxidative stress. EDNO action is improved by administration of ascorbic acid, a water-soluble antioxidant. Ascorbic acid is a potent free-radical scavenger in plasma, and also regulates intracellular redox state in part by sparing cellular glutathione. We specifically investigated the role of intracellular redox state in EDNO action by examining the effect of L-2-oxo-4-thiazolidine carboxylate (OTC) on EDNO-dependent, flow-mediated dilation in a randomized double-blind placebo-controlled study of patients with angiographically proven coronary artery disease. OTC augments intracellular glutathione by providing substrate cysteine for glutathione synthesis. Brachial artery flow-mediated dilation was examined with high-resolution ultrasound before and after oral administration of 4.5 g of OTC or placebo in 48 subjects with angiographically documented coronary artery disease. Placebo treatment produced no change in flow-mediated dilation (7.0+/-3.9% vs. 7.2+/-3.7%), whereas OTC treatment was associated with a significant improvement in flow-mediated dilation (6.6+/-4.4% vs. 11.0+/-6.3%; P = 0.005). OTC had no effect on arterial dilation to nitroglycerin, systemic blood pressure, heart rate, or reactive hyperemia. These data suggest that augmenting cellular glutathione levels improves EDNO action in human atherosclerosis. Cellular redox state may be an important regulator of EDNO action, and is a potential target for therapy in patients with coronary artery disease.

Administration, Oral↗
PubMed2005

Hemolysis-associated endothelial dysfunction mediated by accelerated NO inactivation by decompartmentalized oxyhemoglobin.

During intravascular hemolysis in human disease, vasomotor tone and organ perfusion may be impaired by the increased reactivity of cell-free plasma hemoglobin (Hb) with NO. We experimentally produced acute intravascular hemolysis in a canine model in order to test the hypothesis that low levels of decompartmentalized or cell-free plasma Hb will severely reduce NO bioavailability and produce vasomotor instability. Importantly, in this model the total intravascular Hb level is unchanged; only the compartmentalization of Hb within the erythrocyte membrane is disrupted. Using a full-factorial design, we demonstrate that free water-induced intravascular hemolysis produces dose-dependent systemic vasoconstriction and impairs renal function. We find that these physiologic changes are secondary to the stoichiometric oxidation of endogenous NO by cell-free plasma oxyhemoglobin. In this model, 80 ppm of inhaled NO gas oxidized 85-90% of plasma oxyhemoglobin to methemoglobin, thereby inhibiting endogenous NO scavenging by cell-free Hb. As a result, the vasoconstriction caused by acute hemolysis was attenuated and the responsiveness to systemically infused NO donors was restored. These observations confirm that the acute toxicity of intravascular hemolysis occurs secondarily to the accelerated dioxygenation reaction of plasma oxyhemoglobin with endothelium-derived NO to form bioinactive nitrate. These biochemical and physiological studies demonstrate a major role for the intact erythrocyte in NO homeostasis and provide mechanistic support for the existence of a human syndrome of hemolysis-associated NO dysregulation, which may contribute to the vasculopathy of hereditary, acquired, and iatrogenic hemolytic states.

Animals↗
PubMed1999

Smoking is associated with dose-related increase of intima-media thickness and endothelial dysfunction.

Cigarette smoking is firmly established as a risk factor for atherosclerosis. However, the exact mechanism causing smoking-related damage to the arterial wall and its relation to the atherosclerotic process is not known. Also unknown is the time delay between the start of smoking and the sequence of functional and morphologic changes occurring in the arterial wall caused by smoking and their interrelationship. Therefore, the aim of this study was to evaluate the acute and chronic effects of smoking on endothelium-dependent (flow-mediated) dilation (FMD) of the peripheral arteries, the effects of dose and duration of chronic smoking on intima-media thickness (IMT) of the carotid arteries, and their interrelationship. The study encompassed two groups of smokers. In group A there were 40 subjects of both sexes, who smoked on average 17.6 +/- 6.5 cigarettes per day, for 5 to 15 years (mean 8.95 +/- 4.0 years), mean age 28.1 years. Group B consisted of 42 smokers of both sexes who smoked 21.15 +/- 8.2 cigarettes/day for more than 15 years (mean 21.15 +/- 3.4 years), mean age 39.5 years. The control group consisted of 40 healthy subjects without major risk factors of atherosclerosis, mean age 29.1 years. By means of high-resolution ultrasound the brachial artery diameter was measured at rest and during reactive hyperemia (after release of a forearm tourniquet) and the flow-mediated, endothelium-dependent dilation was calculated. The IMT of the carotid arteries was determined in all subjects by use of B-mode ultrasonography. Resting blood flow in the brachial arteries was significantly less in the smokers' groups than in controls (78.8 +/- 31.9 vs 134.9 +/- 45.0 mL/min, p<0.0001). This decrease was much more evident in female than in male smokers. Female smokers also had significantly smaller brachial artery diameter at rest. In smokers the FMD of the brachial artery was reduced (11 +/- 4% vs 7 +/- 4%, p<0.004) and the mean IMT was significantly greater than in controls (0.68 +/- 0.13 vs 0.59 +/- 0.04 mm, p<0.001). Impairments of FMD and IMT increase were related to the duration and to the number of cigarettes smoked. In all subjects IMT was significantly correlated with total and LDL cholesterol, fibrinogen, lipoprotein(a) concentration, body mass index, and age of the subjects, but multivariate analysis showed that only total dose smoked and fibrinogen concentration were independently related to IMT. The results of this study show that smoking is associated with dose-related impairment of FMD and increased IMT of the carotid arteries. Impairment of FMD occurs in smokers very early and is the earliest detectable event, preceding morphologic changes of the vessel wall. Some harmful effects of smoking on the vessel wall are gender related.

Adult↗
PubMedDate not supplied

Endothelial dysfunction, distensibility and intima-media thickness and aetiology of stroke.

This study measured carotid artery distensibility, intima-media thickness (IMT) and flow-mediated dilatation (FMD) in patients with ischaemic stroke and evaluated if there was a relationship between these measurements and the presence of atrial fibrillation. Distensibility and IMT were measured in 89 patients with ischaemic stroke using ultrasonography; 44 patients had atrial fibrillation. Distensibility was determined using the Reneman equation. FMD was measured in a second group of 52 patients with ischaemic stroke; 20 patients had atrial fibrillation. Patients with atrial fibrillation had lower IMT values compared with patients without atrial fibrillation (0.67 versus 0.79 mm, respectively). Distensibility increased in patients with atrial fibrillation compared with patients without atrial fibrillation (0.19 versus 0.10 mm/100 mmHg, respectively). Patients with atrial fibrillation had significantly better FMD results than patients without atrial fibrillation (5.7% versus 3.2%, respectively). Measuring distensibility, IMT and FMD might be helpful in differentiating between stroke of embolic and thrombotic aetiology.

Aged↗
PubMed2003

Visceral fat accumulation determines postprandial lipemic response, lipid peroxidation, DNA damage, and endothelial dysfunction in nonobese Korean men.

Visceral fat has been associated with multiple cardiovascular disease (CVD) risk factors. The aim of this study was to identify anthropometrical measures most closely associated with some well-known CVD risk factors. Because most Asians at risk have normal body mass index (BMI) according to Western standards, we studied healthy nonobese Korean males (n = 102; age: 36.5 +/- 0.8 years, BMI: 23.8 +/- 0.2 kg/m2). Visceral fat area (VFA) at the fourth lumbar vertebra was associated with increased postprandial triglyceride (TG) response (r = 0.53, P < 0.001) and with plasma malondialdehyde (MDA) (r = 0.36, P < 0.01) and PGF2alpha (r = 0.24, P < 0.05). When matched for BMI and age, men with high VFA (HVFA) (>/=100 cm2; n = 27) had higher blood pressure (P < 0.01), increased consumption of cigarettes (P < 0.01), and lower ratio of energy expenditure to calorie intake (P < 0.01) as compared with low VFA men (<100 cm2; n = 27). Men with HVFA showed higher TG, glucose, and insulin responses following fat and oral glucose tolerance tests respectively higher plasma concentrations of MDA (P < 0.001), urinary PGF2alpha (P < 0.05), and lymphocytes deoxyribonucleic acid tail moments (P < 0.01). Conversely, HVFA was associated with lower testosterone, insulin-like growth factor-1, and brachial artery flow-mediated dilation (P < 0.001). In conclusion, our data indicate that visceral fat accumulation, even in nonobese men, is a major factor contributing to increased CVD risk.

Adipose Tissue↗
PubMed2003

von Willebrand factor and its propeptide in children with diabetes. Relation between endothelial dysfunction and microalbuminuria.

It has been shown that patients with insulin-dependent diabetes mellitus have elevated von Willebrand factor (vWF) plasma concentrations. Plasma fibrinogen, vWF, and its propeptide concentrations have been evaluated in 102 children with insulin-dependent diabetes mellitus to determine whether an increase of vWF and its propeptide levels precedes and may predict the development of persistent microalbuminuria. The patients have been divided into two groups according to the presence or absence of microalbuminuria at the end of follow-up. They have been followed up for at least 8 y. Control group consisted of 80 age- and sex-matched healthy volunteers. At the beginning of the study there was no significant difference in fibrinogen, vWF, and its propeptide levels between patients and control subjects. During the follow-up, a significant increase of plasma vWF and its propeptide has been observed in the group of patients who later developed microalbuminuria but not in those who remained normoalbuminuric. This increase started 3 y and become statistically significant (p < 0.01) 2 y before the onset of microalbuminuria, persisting until the end of the study. During the entire follow-up plasma values of fibrinogen persisted in the normal range. In conclusion, an increase in plasma concentration of vWF and its propeptide precedes microalbuminuria and, therefore, can be useful to identify children with insulin-dependent diabetes mellitus at risk to develop incipient nephropathy later in life.

Albuminuria↗
PubMed1999

Protective effect of dietary tomato against endothelial dysfunction in hypercholesterolemic mice.

The effects of dietary ingestion of tomato were studied in mice that had been made hypercholesterolemic by feeding atherogenic diets. Mice which had been fed on the atherogenic diet without tomato for 4 months had significantly increased plasma lipid peroxide, and the vaso-relaxing activity in the aorta induced by acetylcholine (ACh) was harmed when compared with mice fed on a common commercial diet. On the other hand, mice which had been fed on the atherogenic diet containing 20% (w/w) lyophilized powder of tomato showed less increase in the plasma lipid peroxide level, and ACh-induced vaso-relaxation was maintained at the same level as that in normal mice. These results indicate that tomato has a preventive effect on atherosclerosis by protecting plasma lipids from oxidation.

Acetylcholine↗
PubMed2004

Effect of cerivastatin on endothelial dysfunction and aortic CD36 expression in diabetic hyperlipidemic rats.

A mutation of the CD36 gene that encodes a fatty acid transporter has been reported to play a role in insulin resistance in spontaneously hypertensive rat (SHR). Statins reduce circulating cholesterol and triglyceride concentrations. The objective of this study was to determine the role of CD36 and the significance of statin therapy in insulin-resistance syndromes. We determined the isometric relaxation induced by acetylcholine or lecithinized superoxide dismutase (SOD) in aortas obtained from Otsuka Long Evans Tokushima Fatty (OLETF) rats, a model of insulin resistance and dyslipidemia, and normal control (Long Evans Tokushima Otsuka; LETO) rats with or without cerivastatin treatment. We also determined the effect of cerivastatin on aortic expression of CD36 and PPARgamma. The CD36 genotype and microsatellite markers on chromosome 4 were also determined. The relaxation induced by acetylcholine and lecithinized SOD were attenuated in OLETF rats but restored by a low dose of cerivastatin without significant changes in serum cholesterol. These relaxations were also restored by a high dose of cerivastatin with significant reductions in serum cholesterol and triglyceride. Cerivastatin increased the aortic expression of CD36 and PPARgamma mRNA in both LETO and OLETF rats. However, the basal level of CD36 mRNA and the increase in CD36 mRNA in response to cerivastatin were significantly lower in OLETF rats than in LETO rats. Although the abnormal CD36 genotype reported in SHR was not found in OLETF rats, the microsatellite markers of D4Rat151 and D4Rat115 differed between OLETF and LETO rats. In conclusion, insulin resistance in OLETF rats may be partially due to an altered expression of CD36. Increased aortic expression of CD36 in response to cerivastatin could explain the reduction in serum triglyceride concentrations with statin therapy and may have pronounced beneficial effects in insulin-resistance syndromes.

Animals↗