Comparison of Endothelial Function in Asian Indians Versus Caucasians.

Background: Asian Indians have markedly increased mortality due to coronary artery disease (CAD). Impaired endothelial function has been linked to an increased risk of acute cardiovascular events. We tested the hypothesis that endothelial function was attenuated in Asian Indians and Caucasians.

Gene-specific paradoxical QT responses during rapid eye movement sleep in women with congenital long QT syndrome.

Background: Patients with congenital long QT syndrome (LQTS) type 2 (LQT2) may develop arrhythmias during emotional stress, acoustic stimuli, or sleep. Women with LQT2 are more susceptible to fatal arrhythmias than are men.

Objective: The purpose of this study was to examine the effects of sleep on RR and QT intervals in patients with LQT1, in those with LQT2, and in controls and to test the hypothesis that there is a gene-specific effect of sleep on the QT interval in LQT2 that may be especially evident in women with LQT2.

Leptin upregulates the expression of plasminogen activator inhibitor-1 in human vascular endothelial cells.

A prothrombotic state in obesity may be partially responsible for the higher incidence of atherosclerotic complications. However the factors responsible for this prothrombotic state, linked with high levels of plasminogen activator inhibitor-1 (PAI-1), are not fully known. Leptin is elevated in obesity and studies have shown a positive correlation between leptin and PAI-1 levels in human subjects, along with a negative correlation with tissue-type plasminogen activator (tPA).

Leptin induces C-reactive protein expression in vascular endothelial cells.

Objective: There is increasing evidence of an association between leptin and increased cardiovascular risk. Higher leptin levels are associated with increased levels of C-reactive protein (CRP), which itself elicits proatherogenic effects in the vascular endothelium. We tested the hypothesis that leptin induces CRP expression in human coronary artery endothelial cells (HCAECs).

Hemodynamic and autonomic effects of smokeless tobacco in healthy young men.

Objectives: The aim of this study was to investigate the acute hemodynamic and autonomic effects of smokeless tobacco.

Background: Smokeless tobacco use is increasing. Its cardiovascular effects are not well understood.

Independent association between plasma leptin and C-reactive protein in healthy humans.

Background: C-reactive protein (CRP) is synthesized from the liver and is regulated by cytokines, especially interleukin-6. Leptin, the adipocyte-derived protein product of the ob gene, is related to amount of body fat. The long form of the leptin receptor resembles cytokine receptors, which include the interleukin-6 receptor.

Obesity, sleep apnea, and hypertension.

Obesity has a high and rising prevalence and represents a major public health problem. Obstructive sleep apnea (OSA) is also common, affecting an estimated 15 million Americans, with a prevalence that is probably also rising as a consequence of increasing obesity. Epidemiologic data support a link between obesity and hypertension as well as between OSA and hypertension.

Obstructive sleep apnea: implications for cardiac and vascular disease.

Context: Obstructive sleep apnea (OSA) has been increasingly implicated in the initiation and progression of cardiovascular diseases.

Objective: To systematically review the interactions of OSA with cardiovascular pathophysiology and diseases.

Data Sources And Study Selection: The MEDLINE database from January 1966 to March 2003 was searched using the Medical Subject Headings sleep, sleep apnea, obesity, hypertension, heart failure, cardiac arrhythmia, coronary artery disease, stroke, sympathetic activity, endothelium, inflammation, and continuous positive airway pressure (CPAP) to identify peer-reviewed studies of OSA.

Obstructive sleep apnea and the recurrence of atrial fibrillation.

Background: We tested the hypothesis that patients with untreated obstructive sleep apnea (OSA) would be at increased risk for recurrence of atrial fibrillation (AF) after cardioversion.

Methods And Results: We prospectively obtained data on history, echocardiogram, ECG, body mass index, hypertension, diabetes, NYHA functional class, ejection fraction, left atrial appendage velocity, and medications in patients with AF/atrial flutter referred for DC cardioversion. Forty-three individuals were identified as having OSA on the basis of a previous sleep study.

Sympathetic nerve activity in the congenital long-QT syndrome.

Background: Patients with congenital long-QT syndrome (LQTS) are susceptible to life-threatening arrhythmias. The sympathetic nervous system may have an important triggering role for cardiovascular events in LQTS. We therefore examined measurements of sympathetic neural traffic in patients with LQTS and matched control subjects.

Sex-selective QT prolongation during rapid eye movement sleep.

Background: We examined the effects of the various sleep stages on RR and QT intervals in healthy subjects and tested the hypothesis that there is a differential effect of sleep stage on QT interval in women compared with men.

Methods And Results: Eighteen healthy subjects (9 women, age 22 to 45 years) underwent polysomnography and simultaneous recording of ECG, blood pressure, and respiration. RR interval, RR variability, and QT values were measured in stable conditions (no abrupt changes of heart rate or blood pressure, stable breathing pattern) during inactive wakefulness during stages 2 and 3 to 4 of non-REM sleep and during REM sleep.

Elevated C-reactive protein in patients with obstructive sleep apnea.

Background: Obstructive sleep apnea (OSA) has been increasingly linked to cardiovascular and cerebrovascular disease. Inflammatory processes associated with OSA may contribute to cardiovascular morbidity in these patients. We tested the hypothesis that OSA patients have increased plasma C-reactive protein (CRP).