Darbepoetin enhances endothelium-dependent vasomotor function in patients with stable coronary artery disease only after preceding ischaemia/reperfusion.

Vasoprotective effects of erythropoietin in animal models are mediated by endothelium-derived NO and/or mobilization of EPCs (endothelial progenitor cells) and may be enhanced by ischaemia: whether they are present in humans is unknown. We examined whether the erythropoietin analogue darbepoetin improves FMD (flow-mediated dilatation), a measure of endothelium-derived NO, and whether this is influenced by preceding I/R (ischaemia/reperfusion). A total of 36 patients (50-75 years) with stable coronary artery disease were randomized to receive a single dose of darbepoetin (300 µg) or saline placebo. FMD was measured at the brachial artery using high-resolution ultrasound. CD133⁺/CD34⁺/VEGFR2⁺ (vascular endothelial growth factor receptor 2) circulating EPCs were enumerated by flow cytometry. Measurements were made immediately before darbepoetin/placebo and at 24 h, 72 h and 7 days. At 24 h, FMD was repeated after 20 min of I/R of the upper limb. A further group of 11 patients was studied according to the same protocol, all receiving darbepoetin, with omission of forearm I/R at 24 h. Immunoreactive erythropoietin peaked at 24 h and remained elevated at approximately 50-fold of baseline at 72 h. FMD did not differ significantly between groups at 24 h (before I/R). At 72 h (48 h after I/R), FMD was greater (by 2.3±0.5% in the darbepoetin compared with the placebo group, a 66% increase over baseline; P<0.001) and greater than FMD at the same time point without preceding I/R (P<0.01). Increases in CD133⁺/CD34⁺/VEGFR2⁺ cells after darbepoetin did not differ according to the presence or absence of preceding I/R. Preceding I/R is required for darbepoetin to enhance endothelial function, possibly by increasing expression of the erythropoietin receptor and by a mechanism likely to involve Akt/NO rather than circulating EPCs.

Brachial artery low-flow-mediated constriction is increased early after coronary intervention and reduces during recovery after acute coronary syndrome: characterization of a recently described index of vascular function.

AIMS: The endothelium plays a role in regulating vascular tone. Acute and dynamic changes in low-flow-mediated constriction (L-FMC) and how it changes with regard to traditional flow-mediated dilatation (FMD) have not been described. We aimed to investigate the changes in brachial artery L-FMC following percutaneous coronary intervention (PCI) and during recovery from non-ST-segment elevation myocardial infarction (NSTEMI). METHODS AND RESULTS: FMD was performed in accordance with a previously described technique in patients before and after PCI and in the recovery phase of NSTEMI, but in addition, L-FMC data were acquired from the last 30 s of cuff inflation. About 135 scans were performed in 96 participants (10 healthy volunteers and 86 patients). Measurement of brachial L-FMC was reproducible over hours. L-FMC was greater among patients with unstable vs. stable coronary atherosclerosis (-1.33 ±1.09% vs. -0.03 ± 1.26%, P < 0.01). Following PCI, FMD reduced (4.43 ± 2.93% vs. 1.66 ± 2.16%, P < 0.01) and L-FMC increased (-0.33 ± 0.76% vs. -1.63 ± 1.15%, P = 0.02). Furthermore, during convalescence from NSTEMI, L-FMC reduced (-1.37 ± 1.19% vs. 0.01 ± 0.82%, P = 0.02) in parallel with improvements in FMD (2.54 ± 2.19% vs. 5.15 ± 3.07%, P < 0.01). CONCLUSION: Brachial L-FMC can be measured reliably. Differences were observed between patients with stable and unstable coronary disease. L-FMC was acutely increased following PCI associated with reduced FMD and, in the recovery from NSTEMI, L-FMC reduced associated with increased FMD. These novel findings characterize acute and subacute variations in brachial L-FMC. The pathophysiological and clinical implications of these observations require further study.

Prospective study of placental angiogenic factors and maternal vascular function before and after preeclampsia and gestational hypertension.

BACKGROUND: Preeclampsia is a life-threatening pregnancy syndrome of uncertain origin. To elucidate the pathogenesis, we evaluated the temporal relationships between changes in vascular function and circulating biomarkers of angiogenic activity before and after the onset of preeclampsia and gestational hypertension. METHODS AND RESULTS: Maternal mean arterial pressure, uterine artery pulsatility index, brachial artery flow-mediated dilatation, and serum concentrations of placental growth factor (PlGF), soluble fms-like tyrosine kinase 1 (sFlt-1), and soluble endoglin were prospectively measured in 159 women from 10 weeks gestation until 12 weeks postpartum. At 10 to 17 weeks, women who developed preterm preeclampsia had lower serum PlGF (P=0.003), higher soluble endoglin (P=0.006), and higher sFlt-1:PlGF ratio (P=0.005) compared with women who later developed term preeclampsia, gestational hypertension, or normotensive pregnancy. At 10 to 17 weeks, mean arterial pressure inversely correlated with serum PlGF (r=-0.19, P=0.02); at 18 to 25 weeks, with soluble endoglin (r=0.18, P=0.02); and at 26 to 33 weeks, with sFlt-1 (r=0.28, P<0.001). At 23 to 25 weeks, uterine artery pulsatility index correlated with serum soluble endoglin (r=0.19, P=0.02) and sFlt-1 levels (r=0.17, P=0.03). Flow-mediated dilatation was higher during a pregnancy with gestational hypertension compared with preeclampsia (P=0.001). Twelve weeks postpartum, serum PlGF was higher in women who had a hypertensive pregnancy compared with a normotensive pregnancy (P<0.001). CONCLUSIONS: These observations support a role for placenta-derived angiogenic biomarkers in the control of maternal vascular resistance of preeclampsia. Gestational hypertension develops differently, with a hyperdynamic circulation and angiogenic biomarker profile similar to normotensive pregnancy. Larger studies of unselected women are needed to ascertain whether measures of these angiogenic biomarkers assist with the prediction and prognosis of preeclampsia and whether postpartum measures of serum PlGF have a role in predicting future cardiovascular disease.

Determinants of vascular phenotype in a large childhood population: the Avon Longitudinal Study of Parents and Children (ALSPAC).

AIMS: To assess the feasibility and reproducibility of non-invasive vascular assessment in a childhood population setting and identify the determinants of vascular phenotype in early life. METHODS AND RESULTS: We studied 7557 children (age 9.8-12.3 years) participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). Six research technicians underwent a 5-month training protocol to enable study of brachial artery endothelial function by flow-mediated dilatation (FMD) and arterial stiffness by carotid to radial pulse wave velocity (PWV) and brachial distensibility [distensibility coefficient (DC)]. Reproducibility studies were performed at the beginning, the middle, and the end of the study. A blinded repeat evaluation of a random selection of 3% of the cohort was also undertaken throughout the study. The effect of anthropometric and environmental factors on each measure was examined. Successful measures were obtained in 88, 95, and 87% of the studied children for FMD, PWV, and DC, respectively. The coefficients of variation between technicians for FMD, PWV, and DC were 10.5, 4.6, and 6.6% at the beginning of the study and reached 7.7, 4.1, and 10% at the end. Baseline vessel diameter and gender were important determinants of all the vascular measures, with a small effect of room and skin temperatures on FMD and PWV. Boys consistently had lower FMD and DC and higher PWV measures (P < 0.01 for all). CONCLUSION: Reproducible, high-quality assessments of vascular structure and function in children can be made on a large scale in field studies by suitably trained non-specialist operators. This study provides an invaluable resource for assessing the impact of early influences, genetic, and environmental factors on arterial phenotype.

Endothelial function predicts progression of carotid intima-media thickness.

BACKGROUND: Endothelial dysfunction develops early and has been shown to predict the development of clinical complications of atherosclerosis. However, the relationship between early endothelial dysfunction and the progression of arterial disease in the general population is unknown. We investigated endothelial dysfunction, risk factors, and progression of carotid intima-media thickness (cIMT) in late-middle-aged individuals at low to intermediate cardiovascular risk in a prospective study between 1997 and 2005. METHODS AND RESULTS: Brachial artery flow-mediated dilatation and cIMT were measured in 213 nonsmoking British civil servants recruited from a prospective cohort (Whitehall II study). Participants (age, 45 to 66 years) were free of clinical cardiovascular disease and diabetes mellitus. Risk factors and Framingham Risk Score were determined at baseline. cIMT was repeated 6.2+/-0.4 years later. At baseline, age, blood pressure, low-density lipoprotein cholesterol, and Framingham Risk Score correlated with cIMT. However, only flow-mediated dilatation, not risk factors or Framingham Risk Score, was associated with average annual progression of cIMT. This relationship remained significant after adjustment for risk factors whether entered as separate variables or as Framingham Risk Score. Further adjustment for waist circumference, triglycerides, and employment grade had no significant effect. CONCLUSIONS: Systemic endothelial function was associated with progression of preclinical carotid arterial disease over a 6-year period and was more closely related to cIMT changes than conventional risk factors. Thus, the relationship between endothelial dysfunction and adverse outcome is likely to be due not only to destabilization of established disease in high-risk populations but also to its impact on the evolution of the atherosclerotic substrate. Flow-mediated dilatation testing provides an integrated vascular measure that may aid the prediction of structural disease evolution and represents a potential short- to intermediate-term outcome measure for evaluation of preventive treatment strategies.

Treatment of periodontitis and endothelial function.

BACKGROUND: Systemic inflammation may impair vascular function, and epidemiologic data suggest a possible link between periodontitis and cardiovascular disease. METHODS: We randomly assigned 120 patients with severe periodontitis to community-based periodontal care (59 patients) or intensive periodontal treatment (61). Endothelial function, as assessed by measurement of the diameter of the brachial artery during flow (flow-mediated dilatation), and inflammatory biomarkers and markers of coagulation and endothelial activation were evaluated before treatment and 1, 7, 30, 60, and 180 days after treatment. RESULTS: Twenty-four hours after treatment, flow-mediated dilatation was significantly lower in the intensive-treatment group than in the control-treatment group (absolute difference, 1.4%; 95% confidence interval [CI], 0.5 to 2.3; P=0.002), and levels of C-reactive protein, interleukin-6, and the endothelial-activation markers soluble E-selectin and von Willebrand factor were significantly higher (P<0.05 for all comparisons). However, flow-mediated dilatation was greater and the plasma levels of soluble E-selectin were lower in the intensive-treatment group than in the control-treatment group 60 days after therapy (absolute difference in flow-mediated dilatation, 0.9%; 95% CI, 0.1 to 1.7; P=0.02) and 180 days after therapy (difference, 2.0%; 95% CI, 1.2 to 2.8; P<0.001). The degree of improvement was associated with improvement in measures of periodontal disease (r=0.29 by Spearman rank correlation, P=0.003). There were no serious adverse effects in either of the two groups, and no cardiovascular events occurred. CONCLUSIONS: Intensive periodontal treatment resulted in acute, short-term systemic inflammation and endothelial dysfunction. However, 6 months after therapy, the benefits in oral health were associated with improvement in endothelial function.

Dialysis accelerates medial vascular calcification in part by triggering smooth muscle cell apoptosis.

BACKGROUND: Vascular calcification is associated with increased morbidity and mortality in stage V chronic kidney disease, yet its early pathogenesis and initiating mechanisms in vivo remain poorly understood. To address this, we quantified the calcium (Ca) load in arteries from children (10 predialysis, 24 dialysis) and correlated it with clinical, biochemical, and vascular measures. METHODS AND RESULTS: Vessel Ca load was significantly elevated in both predialysis and dialysis and was correlated with the patients' mean serum Ca x phosphate product. However, only dialysis patients showed increased carotid intima-media thickness and increased aortic stiffness, and calcification on computed tomography was present in only the 2 patients with the highest Ca loads. Importantly, predialysis vessels appeared histologically intact, whereas dialysis vessels exhibited evidence of extensive vascular smooth muscle cell (VSMC) loss owing to apoptosis. Dialysis vessels also showed increased alkaline phosphatase activity and Runx2 and osterix expression, indicative of VSMC osteogenic transformation. Deposition of the vesicle membrane marker annexin VI and vesicle component mineralization inhibitors fetuin-A and matrix Gla-protein increased in dialysis vessels and preceded von Kossa positive overt calcification. Electron microscopy showed hydroxyapatite nanocrystals within vesicles released from damaged/dead VSMCs, indicative of their role in initiating calcification. CONCLUSIONS: Taken together, this study shows that Ca accumulation begins predialysis, but it is the induction of VSMC apoptosis in dialysis that is the key event in disabling VSMC defense mechanisms and leading to overt calcification, eventually with clinically detectable vascular damage. Thus the identification of factors that lead to VSMC death in dialysis will be of prime importance in preventing vascular calcification.

A bimodal association of vitamin D levels and vascular disease in children on dialysis.

In addition to its classical role in calcium-phosphate homeostasis, vitamin D has anti-inflammatory effects that may influence vascular disease. This study examined the impact of vitamin D levels on the vascular phenotype in 61 children who had been on dialysis for >or=3 mo and in 40 age-matched control subjects. All dialysis patients were prescribed daily oral 1-alpha hydroxyvitamin D(3). 92% of patients were deficient in 25-hydroxyvitamin D [25(OH)D]. 1,25-dihydroxyvitamin D [1,25(OH)(2)D] levels were low in 36% and high in 11% of patients. There was a weak correlation between 1 alpha-hydroxyvitamin D(3) dosage and 1,25(OH)(2)D levels. Both carotid intima-media thickness and calcification scores showed a U-shaped distribution across 1,25(OH)(2)D levels: patients with both low and high 1,25(OH)(2)D had significantly greater carotid intima-media thickness (P < 0.0001) and calcification (P = 0.0002) than those with normal levels. Low 1,25(OH)(2)D levels were associated with higher high-sensitivity C-reactive protein (P < 0.0001). Calcification was most frequently observed in patients with the lowest 1,25(OH)(2)D and the highest high-sensitivity C-reactive protein. In contrast, 25(OH)D levels did not correlate with any vascular measure. In conclusion, both low and high 1,25(OH)(2)D levels are associated with adverse morphologic changes in large arteries, and this may be mediated through the effects of 1,25(OH)(2)D on calcium-phosphate homeostasis and inflammation. For optimization of strategies to protect the vasculature of dialysis patients, careful monitoring of 1,25(OH)(2)D levels may be required.

Transient limb ischemia induces remote preconditioning and remote postconditioning in humans by a K(ATP)-channel dependent mechanism.

BACKGROUND: Transient limb ischemia administered before a prolonged ischemic insult has systemic protective effects against ischemia-reperfusion (IR) injury (remote ischemic preconditioning [RIPC]). It has been demonstrated that protection from IR can be achieved by brief periods of ischemia applied at a remote site during an injurious ischemic event (remote postconditioning [RPostC]). Using an in vivo model of endothelial IR injury, we sought to determine whether RPostC occurred in humans and whether it shared mechanistic similarities with RIPC. METHODS AND RESULTS: Endothelial function was assessed by flow-mediated dilation before and after IR (20 minutes of arm ischemia followed by reperfusion). RIPC was induced by conditioning cycles of 5 minutes of ischemia and reperfusion on the contralateral arm or leg before IR. For RPostC induction, conditioning cycles were administered during the ischemic phase of IR. Oral glibenclamide was used to determine the dependence of RIPC and RPostC on K(ATP) channels. IR caused a significant reduction in flow-mediated dilation in healthy volunteers (baseline, 9.3+/-1.2% versus post-IR, 3.3+/-0.7%; P<0.0001) and patients with atherosclerosis (baseline, 5.5+/-0.6% versus post-IR, 2.3+/-0.5%; P<0.01). This reduction was prevented by RIPC (post-IR+RIPC: healthy volunteers, 7.2+/-0.5% [P<0.0001 versus post-IR]; patients, 4.5+/-0.3% [P<0.01 versus post-IR]) and RPostC (post-IR+RPostC: 8.0+/-0.5%; P<0.0001 versus post-IR). The protective effects of RIPC and RPostC were blocked by glibenclamide. CONCLUSIONS: This study demonstrates for the first time in humans that RPostC can be induced by transient limb ischemia and is as effective as RIPC in preventing endothelial IR injury. RIPC and RPostC share mechanistic similarities, with protection being dependent on K(ATP) channel activation. These results suggest that remote conditioning stimuli could be protective in patients with acute ischemia about to undergo therapeutic reperfusion.

The relationship between carotid stiffness and circulating levels of heat shock protein 60 in middle-aged men and women.

OBJECTIVE: There is growing evidence that the presence of the cell stress protein heat shock protein (HSP) 60 in the circulation is associated with risk of coronary heart disease. In this study, we measured the association between plasma HSP60 and carotid arterial stiffness in middle-aged men and women. METHODS: Six hundred and forty-seven men and women aged 50-72 years and free of cardiovascular disease and medication were tested. Carotid artery distensibility coefficient was assessed ultrasonically as a measure of arterial stiffness, and plasma HSP60 was assessed using a sensitive immunoassay. RESULTS: We found a significant, independent association between high plasma levels of HSP60 and increased carotid stiffness. Carotid distensibility coefficient was also related to diabetes, adiposity, blood pressure, lipids, plasma interleukin-6 and C-reactive protein. After adjusting for these factors, the odds of HSP60 concentration of at least 1000 ng/ml were 1.79 (95% confidence intervals 1.06-3.04) for participants in the lowest compared with the highest tertile of the distensibility coefficient. CONCLUSION: HSP60 is a potent activator of vascular endothelial cells and smooth muscle cells. Thus, it is possible that long-term stimulation of these cell populations by blood-borne HSP60 acts to drive blood vessel changes resulting in decreased arterial elasticity.

Arterial stiffness and inflammatory response to psychophysiological stress.

The processes through which psychological stress influences cardiovascular disease are poorly understood, but may involve activation of hemodynamic, neuroendocrine and inflammatory responses. We assessed the relationship between carotid arterial stiffness and inflammatory responses to acute psychophysiologic stress. Participants were 155 healthy men and women aged 55.3, SD 2.7 years. Blood samples for the assessment of plasma fibrinogen, tumor necrosis factor (TNF) alpha and interleukin (IL) 6 were drawn at baseline, immediately following standardized behavioral tasks, and 45 min later. Carotid artery stiffness was measured ultrasonically three years later, and blood pressure and heart rate responses were recorded. The tasks induced substantial increases in blood pressure and heart rate, together with increased fibrinogen, TNFalpha and IL-6 concentration. Carotid stiffness was positively associated with body mass, waist/hip ratio, blood pressure, low density lipoprotein cholesterol, and C-reactive protein, and inversely with high density lipoprotein and grade of employment. Baseline levels of inflammatory variables were not related to carotid artery stiffness. But carotid stiffness was greater in participants with larger fibrinogen (p=0.037) and TNFalpha (p=0.036) responses to psychophysiological stress. These effects were independent of age, gender, grade of employment, smoking, body mass, waist/hip ratio, systolic and diastolic pressure, high and low density lipoprotein cholesterol, and C-reactive protein. There were no associations between carotid stiffness and stress responses in IL-6, blood pressure, or heart rate. We conclude that individual differences in inflammatory responses to psychophysiological stress are independently related to structural changes in artery walls that reflect increased cardiovascular disease risk.

Systemic vascular endothelial dysfunction in Peyronie's disease.

INTRODUCTION: Many patients with Peyronie's disease (PD) have one or more risk factors (RFs) for atherosclerosis and endothelial dysfunction. It is well recognized that such RFs commonly lead to the development of systemic vascular abnormalities. While not necessarily so, this may implicate vascular dysfunction in its pathogenesis. The cause of PD remains obscure despite intense research over the years and investigating the role of vascular dysfunction in the pathogenesis of PD is a novel approach worth undertaking. AIM: To test our hypothesis that PD is associated with systemic vascular changes even in the absence of RFs for atherosclerosis and endothelial dysfunction. METHODS: Vascular function was assessed using high-resolution brachial artery ultrasound in 23 PD patients (aged 30-65 years) without RFs for endothelial dysfunction and atherosclerosis, and 23 age-matched healthy controls. Endothelium-dependent, flow-mediated brachial artery dilation was measured in response to increased shear stress (reactive hyperemia induced by 5 minutes of forearm ischemia). This response was contrasted with that of 400 microg sublingual glyceryl trinitrate, an endothelium-independent vasodilator. Anthropometric characteristics, blood pressure, fasting lipids, and glucose were also measured. MAIN OUTCOME MEASURE: Endothelium-dependent, flow-mediated brachial artery dilation and glyceryl trinitrate-induced endothelium-independent vasodilation. RESULTS: Endothelium-dependent flow-mediated dilation (FMD) was impaired in PD patients compared to controls (5.62 +/- 0.58% vs. 7.46 +/- 0.56%, P = 0.03). In contrast, responses to glyceryl trinitrate were similar in PD patients and controls as were blood pressure, lipid, and glucose values. FMD remained impaired after multivariable adjustment for potential confounders. CONCLUSION: Patients with Peyronie's disease have evidence of systemic vascular changes in the way of systemic conduit artery endothelial impairment even in the absence of RFs for atherosclerosis and endothelial dysfunction. These wider vascular abnormalities in PD are likely to be of clinical relevance and require further study.

Mineral metabolism and vascular damage in children on dialysis.

Cardiovascular disease is increasingly recognized as a life-limiting problem in young patients with chronic kidney disease, but there are few studies in children that describe its determinants. We studied the association of intact parathyroid hormone (iPTH) levels and their management on vascular structure and function in 85 children, ages 5-18 years, who had received dialysis for > or =6 months. Compared to controls, dialysis patients had increased carotid intima-media thickness and pulse-wave velocity. All vascular measures positively correlated with serum phosphorus levels, while carotid intima-media thickness and cardiac calcification score also correlated with iPTH levels. Patients with mean time-integrated iPTH levels less than twice the upper limit of normal (n = 41) had vascular measures that were comparable to age-matched controls, but those with iPTH levels greater than twice the upper limit of normal (n = 44) had greater carotid intima-media thickness, stiffer vessels, and increased cardiac calcification than controls. Patients with increased carotid intima-media thickness had stiffer vessels and a greater prevalence of cardiac calcification. There was a strong dose-dependent correlation between vitamin D and all vascular measures, and calcium intake from phosphate binders weakly correlated with carotid intima-media thickness. In conclusion, both iPTH level and dosage of vitamin D are associated with vascular damage and calcification in children on dialysis.

Measurement of endothelial function and its clinical utility for cardiovascular risk.

Over the past two decades, the central role of the endothelium in the initiation, progression, and clinical sequelae of atherosclerosis has been increasingly recognized. Assessment of the pathobiology of the endothelium and its ability to act as a potential therapeutic target remains an area of active research interest. Whilst endothelial function has been shown to be a marker for risk of cardiovascular events in high-risk groups, there remains considerable debate about the most appropriate way to assess this. We discuss the different clinical methods to assess endothelial function, focusing on flow-mediated dilatation (FMD) of the brachial artery, highlighting the importance of using a standardized methodology, as well as discussing the clinical limitations of using FMD in individuals.

Delayed blood pressure recovery after psychological stress is associated with carotid intima-media thickness: Whitehall psychobiology study.

OBJECTIVE: Delayed blood pressure (BP) recovery after psychological stress is associated with low socioeconomic status (SES) and prospectively with increases in clinic BP. We tested whether poststress BP recovery was related to carotid atherosclerosis. METHODS AND RESULTS: Psychophysiological stress testing was performed with a healthy subgroup of the Whitehall II epidemiological cohort, and recovery systolic BP was monitored 40 to 45 minutes after stressful behavioral tasks. Carotid ultrasound scanning was conducted on 136 men and women (aged 55.3+/-2.7 years) 3 years after stress testing. Participants were divided into those whose systolic BP had returned to baseline in the recovery period (adequate recovery, n=37), and those whose BP remained elevated (delayed recovery, n=99). Systolic BP stress responses did not differ in the 2 groups. Carotid intima-media thickness (IMT) was associated with delayed recovery in lower SES (means 0.78 versus 0.65 mm) but not higher SES participants (means 0.75 versus 0.74 mm) after adjustment for age, gender, baseline systolic BP, and resting BP, smoking, body mass and fasting cholesterol at the time of ultrasound scanning (P=0.010). CONCLUSIONS: Variations in poststress recovery reflect dysfunction of biological regulatory processes, and may partly mediate psychosocial influences on cardiovascular disease.

Systemic Acyl-CoA:cholesterol acyltransferase inhibition reduces inflammation and improves vascular function in hypercholesterolemia.

BACKGROUND: Circulating lipids may initiate and progress atherosclerosis by causing vascular inflammation. Monocytes and tissue macrophages are involved and regulate lipid metabolism in the vascular wall through acetylation of cholesterol by acyl-CoA:cholesterol acyltransferase (ACAT). ACAT inhibition reduces atherosclerosis in animal models by mechanisms that may be independent of their effects on circulating lipids. Because endothelial dysfunction is an important factor in atherosclerosis, we tested the hypothesis that systemic ACAT inhibition would improve endothelial function in hypercholesterolemic humans and assessed its effects on circulating lipids and markers of systemic inflammation. METHODS AND RESULTS: We studied 21 hypercholesterolemic subjects in a double-blind, randomized-crossover, placebo-controlled trial with assessments of circulating lipids, markers of inflammation, resistance-vessel endothelial function (with venous occlusion plethysmography), and conduit-vessel vasoreactivity (brachial artery flow-mediated dilation at baseline and after placebo or treatment with avasimibe 750 mg QDS for 8 weeks. There was a small change in total cholesterol with treatment (326+/-25 to 311+/-22 mg/dL, P=0.04). Circulating tumor necrosis factor-alpha was significantly reduced (4.0+/-0.3 to 3.6+/-0.2 pg/mL, P=0.02); resistance vessel responses to acetylcholine, bradykinin, and verapamil were significantly enhanced; and responses to nitroglycerin and conduit-vessel vasoreactivity were unchanged after ACAT inhibition. CONCLUSIONS: Systemic ACAT inhibition reduces circulating tumor necrosis factor-alpha levels in hypercholesterolemic subjects and improves resistance-vessel endothelial function, with small effects on circulating cholesterol. This may be a novel therapeutic strategy to target vascular inflammation and endothelial dysfunction in atherosclerosis.

Endothelial dysfunction in childhood infection.

BACKGROUND: Atherosclerosis begins in early life, and endothelial dysfunction is recognized as a key initiating event in the development of atherosclerosis. Although infection has been implicated in endothelial dysfunction and atherogenesis, the impact of acute common childhood infections on the vascular endothelium is unknown. METHODS AND RESULTS: We studied 600 children aged 10 years drawn from the Avon Longitudinal Study of Parents and Children. The children were divided into 3 groups: those with current acute infection (AI; n=135; 73 boys and 62 girls); a convalescent group with infection in the past 2 weeks (n=166; 78 boys and 88 girls), and a healthy control group (n=299; 131 boys and 168 girls). Endothelial function was determined in all subjects by high-resolution ultrasound to measure brachial artery flow-mediated dilation (FMD) and was expressed as the percentage change in diameter from baseline after reactive hyperemia. FMD was repeated in 40 children in the AI group and 50 in the control group after a mean interval of 1 year. FMD was lower in both the AI group (6.3+/-2.7%, mean+/-SD) and the convalescent group (8.1+/-3.1%) than in the control group (9.7+/-2.5%; P<0.001 for both). The observed differences in FMD remained after adjustment for potential confounding variables. At the repeat visit, FMD was unchanged in controls (P=0.85) but improved in the AI group (P<0.001). CONCLUSIONS: Acute infection in childhood is associated with impaired endothelium-dependent vasodilation. These findings support a potential role for previously unsuspected extrinsic inflammatory stimuli in the pathogenesis of early atherosclerosis.

Early structural and functional changes of the vasculature in HIV-infected children: impact of disease and antiretroviral therapy.

BACKGROUND: Premature cardiovascular disease is increasingly recognized in HIV-infected patients, but the mechanisms involved are unclear. The purpose of this study was to determine the impact of HIV infection and antiretroviral therapy (ART) on markers of early vascular disease in children. METHODS AND RESULTS: We studied 83 HIV-infected children (56 had taken ART, of whom 31 received a regimen containing protease inhibitors [PIs]; 27 were never treated) and a control group of 59 healthy children. Carotid intima-media thickness (IMT) and brachial artery flow-mediated dilatation (FMD) were measured. IMT was significantly greater in HIV-infected children compared with the control subjects (P<0.001). Among the HIV-infected children, age and treatment were significantly associated with increased IMT. Children exposed to PIs had greater IMT compared with both non-PI-treated children and untreated children (P=0.02). FMD was also significantly reduced in the HIV-infected children compared with control subjects (P=0.02). Pairwise comparisons of different treatment exposure groups revealed that FMD was impaired by a mean of 3.6% (95% CI, 1.8 to 5.3; P<0.001) for children exposed to PIs compared with untreated children and by a mean of 1.8% (95% CI, 0.01 to 3.5; P=0.05) compared with non-PI-treated children. HIV-infected children had lipid abnormalities, but they did not account for the observed differences in either FMD or IMT. CONCLUSIONS: HIV infection in childhood is associated with adverse structural and functional vascular changes that are most pronounced in children exposed to PI therapy. Longitudinal studies are required to differentiate the relative impact of HIV disease and ART and to assess the potential for prevention.

Remote ischemic preconditioning provides early and late protection against endothelial ischemia-reperfusion injury in humans: role of the autonomic nervous system.

OBJECTIVES: The aim of this study was to characterize the time course and neuronal mechanism of remote ischemic preconditioning (RIPC) of the vasculature in humans. BACKGROUND: Non-lethal ischemia of internal organs induces local (ischemic preconditioning) and systemic (RIPC) resistance to lethal ischemia-reperfusion (IR) injury. Experimental RIPC has two temporal components, is neuronally mediated, is induced by limb ischemia, and reduces infarct size. In humans, RIPC prevents IR-induced vascular injury. Determining the time course and mechanism is a prelude to clinical outcome studies of RIPC. METHODS: Endothelial IR injury was induced by arm ischemia (20 min) and reperfusion, and measured by flow-mediated dilation. To establish if there are early and late phases, RIPC (three 5-min cycles of ischemia of the contralateral arm) was applied immediately, 4, 24, and 48 h before IR. To determine neuronal involvement, trimetaphan (autonomic ganglion blocker; 1 to 6 mg/min intravenous) was infused during the application of the RIPC stimulus. RESULTS: Flow-mediated dilation was reduced by IR (8.7 +/- 1.1% before IR, 4.9 +/- 1.2% after IR; p < 0.001), but not when preceded by RIPC (8.0 +/- 0.8% after IR; p = NS); RIPC did not protect after 4 h (4.9 +/- 1.1% after IR; p < 0.001), but protected at 24 (8.7 +/- 1.1% after IR; p = NS) and 48 h (8.8 +/- 1.4% after IR; p = NS). Trimetaphan attenuated early (8.3 +/- 1.1% before IR, 4.2 +/- 0.9% after IR; p < 0.05) and delayed (7.3 +/- 1.0% before IR, 2.3 +/- 0.6% after IR, p < 0.001) RIPC. CONCLUSIONS: Remote ischemic preconditioning in humans has two phases of protection against endothelial IR injury; an early (short) and late (prolonged) phase, both of which are neuronally mediated. The potential for late phase RIPC to provide prolonged protection during clinical IR syndromes merits investigation.

Circadian variation in endothelial function is attenuated in postmenopausal women.

OBJECTIVE: The present study was undertaken to investigate the possible existence of an endogenously generated circadian rhythm in endothelial function in women and whether this rhythm is altered after the menopause. METHODS: Healthy non smoking women (11 pre-menopausal and 13 postmenopausal women) were studied during a 22 h period under constant routine conditions; endothelium-dependent (flow-mediated dilation (%FMD)) and -independent (glyceryl-trintrate (GTN)-mediated) function was assessed every 2 and 4 h, respectively, by high-resolution ultrasound of the brachial artery. RESULTS: %FMD and %GTN was significantly higher in pre-menopausal women (9.9+/-1.0%FMD (mean+/-S.E.M.); 18.2+/-1.8%GTN; P<0.01) compared with postmenopausal women (6.5+/-0.5%FMD; 11.5+/-1.6%GTN). A significant day-night variation in %FMD was observed pre-menopausal women (day 9.2+/-0.8%; night 10.4+/-1%; P<0.05) with an attenuated rhythm in postmenopausal women (day 6.8+/-0.6%; night 6.0+/-0.4%). CONCLUSIONS: The findings show a circadian rhythm in %FMD in pre-menopausal women, which disappears after the menopause. The reduction in %FMD and an absence of a day-night variation in %FMD in postmenopausal women may have important implications for the incidence of coronary heart disease in women after the menopause.