Macroangiopathy--does it play a role in young people?

Using a novel ultrasound method, brachial artery endothelial and smooth muscle physiology were studied in 20 adolescents with IDDM and in 20 nondiabetic subjects matched for age (13-22 years), gender and vessel size. Endothelium-dependent dilatation (EDD) was assessed in response to flow (EDD) and endothelium-independent vasodilatation after sublingual glyceryl trinitrate (GTN). Both EDD and GTN were reduced in those with IDDM compared with controls: 5 vs. 9%, (p = 0.0002) and 14 vs. 21% (p = 0.002). Abnormal EDD was found in 12 IDDM adolescents (diabetes duration 3.3-14.9 years). The mean urinary albumin excretion rate of the diabetic group with abnormal EDD was 5.76 +/- 2.82 vs. 8.05 +/- 4.88 microg/min in those with normal EDD (p = 0.25). In the diabetic adolescents there was no significant correlation observed between the test for early large vessel disease, HbAlc and tests for diabetic microangiopathy.

The impact of heavy passive smoking on arterial endothelial function in modernized Chinese

OBJECTIVES

The study evaluated whether heavy exposure to environmental tobacco smoke (passive smoking) might damage arterial function in modernized Chinese.

BACKGROUND

Heavy passive smoking is associated with arterial endothelial dysfunction in Caucasian, but not rural Chinese, subjects.

METHODS

We studied 20 young (mean age 36.6 +/- 7.0 years) nonsmoking asymptomatic casino workers (9 men) in Macau who were exposed to environmental tobacco smoke for over 8 h/day for at least two years and 20 normal subjects (control subjects). These two groups were carefully matched for age, gender, body mass index (BMI), blood pressure, vessel diameter, cholesterol and glucose levels. Brachial artery diameter was measured by high-resolution B-mode ultrasound at rest, after flow increase (causing flow-mediated endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator).

RESULTS

Flow-mediated dilation (mean +/- SD% of diameter changes) was significantly lower in passive smokers (6.6 +/- 3.4%) compared with the controls (10.6 +/- 2.3%) (p < 0.0001). Nitroglycerin-induced dilation of the two groups were similar. Upon multivariate analysis, passive smoking exposure was the strongest independent predictor (beta = -0.59; p = 0.0001) for impaired flow-mediated endothelium-dependent dilation (model R2 = 0.75, F value = 6.1, p = 0.0001).

CONCLUSIONS

In modernized Chinese, as in Caucasians, exposure to heavy environmental tobacco smoke causes arterial endothelial dysfunction, a key early event in atherosclerosis. This may have serious implications for cardiovascular health in China, currently in a process of rapid modernization.

Enhanced peripheral vasodilation in humans after a fatty meal

OBJECTIVES

We sought to study the effects of a fatty meal on vascular reactivity, including endothelial function and maximal vasodilation.

BACKGROUND

Recent reports regarding the physiological changes in peripheral vasculature after eating a fatty meal have been controversial.

METHODS

Twelve volunteers were studied before, 3 h after, and 6 h after a high-fat meal (1030 kcal, 61 g fat) rich in saturated fatty acids, and 10 were restudied after a similar meal rich in monounsaturated fatty acids. Endothelial function was assessed as flow-mediated dilatation (FMD) in the brachial artery using ultrasound. Resting and postischemic forearm blood flow (FBF) were recorded using venous occlusion strain-gauge plethysmography, before, and every 10 to 15 s after, 5 min upper arm ischemia.

RESULTS

Brachial artery basal diameter, resting FBF and postischemic hyperemia increased after high-fat meals (all p<0.001), whereas FMD did not change. The increase in resting FBF correlated with increases in postprandial insulin (r = 0.80, p<0.002) and triglyceride (r = 0.77, p<0.005) levels.

CONCLUSIONS

We concluded that eating a fatty meal induces vasodilation and increases resting and stimulated FBF and that these observations are probably mediated by postprandial changes in insulin and/or triglyceride levels. The metabolic changes that occur after meals are not associated with impaired endothelial nitric oxide release in the conduit arteries.

Transvenous echo Doppler in baboons: a new window to the cardiovascular system

Ultrasound examinations of the heart and major peripheral arteries have been performed as separate procedures; both potentially limited by suboptimal views in certain subjects and the inability to obtain ideal pictures of particular intracardiac structures. Transvenous ultrasound may offer new advantages in certain areas, we therefore studied six adult baboons using a single-plane 5.5-10 MHz transducer mounted on a 10 French (10F) catheter, introduced via the right femoral vein and positioned under fluoroscopic control. Imaging and Doppler studies were performed to delineate cardiovascular anatomy as well as ventricular function response to positive (dobutamine) and negative inotropic (esmolol) agents. The procedure was safe and feasible in all cases. Clear and novel two-dimensional and flow information were obtained from the iliac arteries, descending aorta, both renal artery origins, ascending aorta, including the aortic arch, main pulmonary artery and its bifurcation, as well as head and neck vessels. Novel intracardiac views were obtained, including right ventricular long axis, left ventricular apex and 'flask' views of the left ventricle. Excellent dynamic information for left ventricular function was also available [e.g. myocardial Vmax of the anterior left ventricular wall was 6.8+/-2.5 cm/s at rest, 14.6+/-5.5 cm/s after dobutamine (P=0.009) and 4.5+/-1 cm/s after esmolol (P=0.03 compared with control)]. We conclude that, in adult primates, transvenous ultrasound safely and reliably provides novel information of cardiovascular structure and function.

Testing for endothelial dysfunction

Endothelial health is a key factor in normal cardiovascular homeostasis, and recent studies have revealed several important functions of the vascular endothelium that protect against atherothrombosis. These include control over arterial tone, coagulation, fibrinolysis, and vascular growth. Consequently, endothelial dysfunction has been implicated as an important event in the pathogenesis of atherosclerosis, coronary vasoconstriction, hypertension, and myocardial ischaemia. Therefore, there has been considerable research interest in diagnostic assays for the assessment of endothelium. This review outlines the current status of markers of endothelial dysfunction, particularly those related to vasomotor control, as well as circulating markers of vascular health.

Phytoestrogens do not influence lipoprotein levels or endothelial function in healthy, postmenopausal women

Plant estrogen or phytoestrogens (PE) are increasingly consumed for the purposes of menopause symptom relief and prevention of cardiovascular and other diseases. The objective of this study was to evaluate the effects of PE on plasma lipids and lipoproteins and on endothelial function. Twenty healthy, postmenopausal women, 50 to 70 years old, and with evidence of endothelial dysfunction, were treated with a soybean PE tablet of 80 mg/day of isoflavones. Endothelial function was assessed noninvasively using brachial ultrasound. A double-blind, placebo-controlled, randomized crossover design was employed. After 3 weeks stabilization on a standard fat-reduced diet, subjects received PE or placebo for 8 weeks in random order, separated by a washout period of 8 weeks. Compared with placebo, there were no significant effects of PE on blood pressure and plasma lipid or lipoprotein concentrations. Flow-mediated endothelium-dependent dilation (FMD) in response to reactive hyperemia was not significantly changed by PE ingestion (3. 3 +/- 0.7% on placebo vs 4.1 +/- 0.7% on PE, p >0.4). Variation in FMD was not correlated with change in plasma isoflavone concentration (r = -0.09, p >0.7). Glyceryl trinitrate endothelium-independent dilation was not significantly changed with PE (15.9 +/- 1.3% vs 13.7 +/- 1.2%, p >0.1). These results fail to show a significant impact of medium-term supplementation with 80 mg/day of isoflavones on lipid and lipoprotein levels or on endothelial function in healthy, postmenopausal women.

Oral vitamin C and endothelial function in smokers: short-term improvement, but no sustained beneficial effect

OBJECTIVES

To test the hypothesis that antioxidant therapy would improve endothelial function in smokers.

BACKGROUND

Several studies have documented a beneficial effect of short-term oral or parenteral vitamin C on endothelial physiology in subjects with early arterial dysfunction. Possible long-term effects of vitamin C on endothelial function, however, are not known.

METHODS

We studied the effects of short- and long-term oral vitamin C therapy on endothelial function in 20 healthy young adult smokers (age 36 +/- 6 years, 8 male subjects, 21 +/- 10 pack-years). Each subject was studied at baseline, 2 h after a single dose of 2 g vitamin C and 8 weeks after taking 1 g vitamin C daily, and after placebo, in a randomized double-blind crossover study. Blood samples were analyzed for plasma ascorbate levels and endothelial function was measured as flow-mediated dilation of the brachial artery, using high resolution ultrasound. Nitroglycerin-mediated dilation (endothelium-independent) was also measured at each visit.

RESULTS

At baseline, plasma ascorbate level was low in the smokers (42 +/- 21 micromol/liter; normal range, 50 to 150 micromol/liter), increased with vitamin C therapy after 2 h to 120 +/- 54 micromol/liter (p < 0.001) and remained elevated after eight weeks of supplementation at 92 +/- 32 micromol/liter (p < 0.001, compared with placebo). Flow-mediated dilation, however, increased at 2 h (from 2.8 +/- 2.0% to 6.3 +/- 2.8%, p < 0.001), but there was no sustained beneficial effect after eight weeks (3.9 +/- 3.2%, p = 0.26). Nitroglycerin-mediated dilation was unchanged throughout.

CONCLUSION

Oral vitamin C therapy improves endothelial dysfunction in the short term in healthy young smokers, but it has no beneficial long-term effect, despite sustained elevation of plasma ascorbate levels.

Role of ischemia and infarction in late right ventricular dysfunction after atrial repair of transposition of the great arteries

OBJECTIVES

This study was conducted to assess whether myocardial ischemia and/or infarction are involved in the pathogenesis of late right ventricular dysfunction in adult survivors of atrial baffle repair for transposition of the great arteries in infancy.

BACKGROUND

The medium-term success of intraatrial baffle repair for transposition of the great arteries is good, with many patients surviving into adult life, but prognosis can be limited by progressive right ventricular dysfunction. We hypothesized that ongoing myocardial ischemia and/or infarction are important factors in the pathogenesis of this complication. Radionuclide techniques offer an opportunity to study both myocardial perfusion and concomitant ventricular wall motion.

METHODS

Dipyridamole sestamibi single-photon emission computed tomography followed by rest sestamibi single-photon emission computed tomography was used to assess right ventricular myocardial perfusion, wall motion, wall thickening and ejection fraction in 22 adolescents/young adults who had undergone atrial baffle repair for simple transposition of the great arteries at median 6.7 (range 0.5 to 54) months of age. The patients were aged 10 to 25 (median 15.5) years; 19 in New York Heart Association class I, 2 in class II and 1 in class III. All were in a regular cardiac rhythm during the studies. The right ventricular tomographic images were examined in three parallel and two orthogonal planes, analyzed in 12 segments.

RESULTS

Perfusion defects were evident in all patients in at least one segment, in either the rest or stress images. Twelve patients (55%) demonstrated fixed defects only, nine (41%) had fixed and reversible defects and one (4.5%) had reversible defects only. Concomitant wall-thickening abnormalities occurred in 83% of segments with fixed perfusion defects, mirrored by a reduction in wall motion in 91% of segments analyzed. Right ventricular ejection fraction was correlated with age (R = 0.62; p = 0.002), and with wall-thickening abnormalities (R = 0.60; p < 0.005).

CONCLUSIONS

Reversible and fixed perfusion defects with concordant regional wall motion abnormalities occur in the right (systemic) ventricle 10 to 20 years after Mustard repair for transposition of the great arteries; this may be important in the pathogenesis of late right ventricular dysfunction in this group.

A comparison of endothelial function in Caucasian and Chinese women before and after the menopause

OBJECTIVE

Arterial endothelial dysfunction is a key atherogenic event that may be related to oestrogen status. We therefore aimed to compare menopause-related changes in endothelial physiology in Chinese and Caucasian females.

METHODS

We studied 40 female subjects; 20 Chinese from a rural region of Southern China (ten premenopausal, aged 20-35 years, and ten postmenopausal, aged 55-66 years), and 20 age-matched Caucasian females from Sydney, Australia. All women had a clinical history, resting blood pressure and fasting lipids measured, and endothelial function assessed. Using high-resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilatation) and after sublingual glyceryl trinitrate (GTW) (an endothelium-independent dilator).

RESULTS

There was a significant decline in endothelium-dependent dilatation (EDD) comparing Caucasian females from the premenopausal versus postmenopausal groups (8.4+/-2.7% versus 2.7+/-2.9%; P<0.001). In contrast, there was no significant difference in EDD between pre- and postmenopausal Chinese (9.8+/-3.3% versus 8.3+/-1.7%; P=0.22). On multivariate analysis, postmenopausal status was associated with impaired EDD in Caucasian females (P<0.002) independent of serum cholesterol, blood pressure and vessel size. In contrast, EDD in the Chinese females was not significantly influenced by any of these factors. GTW-induced dilatation was also impaired in the older Caucasian females, a finding explained on multivariate analysis by the increased vessel size in this patient group (P=0.03).

CONCLUSION

Menopause is associated with impaired arterial endothelial function in Caucasian but not Chinese women. This suggests possible ethnic differences in menopause-related vascular changes.

Coenzyme Q improves LDL resistance to ex vivo oxidation but does not enhance endothelial function in hypercholesterolemic young adults

Oxidative modification of low-density lipoprotein (LDL) may cause arterial endothelial dysfunction in hyperlipidemic subjects. Antioxidants can protect LDL from oxidation and therefore improve endothelial function. Dietary supplementation with coenzyme Q (CoQ(10)) raises its level within LDL, which may subsequently become more resistant to oxidation. Therefore, the aim of this study was to assess whether oral supplementation of CoQ(10) (50 mg three times daily) is effective in reducing ex vivo LDL oxidizability and in improving vascular endothelial function. Twelve nonsmoking healthy adults with hypercholesterolemia (age 34+/-10 years, nine women and three men, total cholesterol 7.4+/-1.1 mmol/l) and endothelial dysfunction (below population mean) at baseline were randomized to receive CoQ(10) or matching placebo in a double-blind crossover study (active/placebo phase 4 weeks, washout 4 weeks). Flow-mediated (FMD, endothelium-dependent) and nitrate-mediated (NMD, smooth muscle-dependent) arterial dilatation were measured by high-resolution ultrasound. CoQ(10) treatment increased plasma CoQ(10) levels from 1.1 +/-0.5 to 5.0+/-2.8 micromol/l (p =.009) but had no significant effect on FMD (4.3+/-2.4 to 5.1+/-3.6 %, p =.99), NMD (21.6+/-6.1 to 20.7+/-7.8 %, p = .38) or serum LDL-cholesterol levels (p = .51). Four subjects were selected randomly for detailed analysis of LDL oxidizability using aqueous peroxyl radicals as the oxidant. In this subgroup, CoQ(10) supplementation significantly increased the time for CoQ(10)H(2) depletion upon oxidant exposure of LDL by 41+/-19 min (p = .04) and decreased the extent of lipid hydroperoxide accumulation after 2 hours by 50+/-37 micromol/l (p =.04). We conclude that dietary supplementation with CoQ(10) decreases ex-vivo LDL oxidizability but has no significant effect on arterial endothelial function in patients with moderate hypercholesterolemia.

Androgen receptor expression is greater in macrophages from male than from female donors. A sex difference with implications for atherogenesis

BACKGROUND

Male sex is an independent risk factor for the extent and severity of atherosclerosis. The influence of androgens on foam cell formation, a key event in atherogenesis, has not yet been investigated.

METHODS AND RESULTS

Primary human monocytes were allowed to differentiate into macrophages. RNA was then extracted from healthy male-donor (n=8) and premenopausal female-donor (n=8) macrophages, and message for the androgen receptor (AR) was examined by RT-PCR. There was a significantly higher level of AR mRNA in macrophages isolated from men than in those from women (0.64+/-0.06 versus 0.15+/-0.02 amol/microgram total RNA; P<0.001). AR mRNA levels were similar in macrophages from postmenopausal and premenopausal women (P=0.16). The functional consequence of this sex difference was then explored. Lipid-loading studies were performed on male (n=9) macrophages treated with the androgen dihydrotestosterone (DHT) and/or the AR antagonist hydroxyflutamide. These showed that DHT caused a dose-dependent and receptor-mediated increase in macrophage cholesteryl ester content (109+/-10%, 117+/-3%, and 120+/-4% for 4, 40, and 400 nmol/L DHT, respectively, as a percentage of control, P=0.002; 95+/-8% for DHT with hydroxyflutamide, P=0.58 versus controls). By contrast, there was no significant effect of androgen on lipid loading in female-donor macrophages (P>0.2 versus controls).

CONCLUSIONS

Sex differences in androgen-mediated macrophage lipid loading may contribute to the greater prevalence and severity of atherosclerosis in men.

Estrogen and progesterone reduce lipid accumulation in human monocyte-derived macrophages: a sex-specific effect

BACKGROUND

Males have an earlier onset and greater prevalence of clinical atherosclerosis than age-matched females, which is consistent with an atheroprotective effect of the female sex steroids, estrogen and progesterone. We therefore examined the effects of estrogen and progesterone on human foam cell formation, a key early event in atherogenesis.

METHODS AND RESULTS

Monocytes from healthy female and male donors were obtained from white cell concentrates and allowed to differentiate into macrophages over 10 days. These human monocyte-derived macrophages (MDMs) were exposed to either control (0.1% vol/vol ethanol) or estrogen or progesterone treatment on days 3 through 10. Lipid loading was achieved on days 8 through 10 by incubation with acetylated LDL. Lipid from the MDMs was then extracted for analysis of cholesteryl ester (CE) content. 17beta-Estradiol at both physiological (2 nmol/L) and supraphysiological (20 and 200 nmol/L) concentrations produced a significant reduction in macrophage CE content (88+/-3%, 88+/-2%, and 85+/-4%, respectively; P<0.02 compared with control). Physiological and supraphysiological levels of progesterone (2, 10, and 200 nmol/L) produced an even more dramatic reduction in CE content (74+/-9%, 56+/-10%, and 65+/-8%, respectively; P<0.002 compared with control). This effect could be abrogated by coincubation with the progesterone receptor antagonist RU486. Neither estrogen nor progesterone produced a reduction in lipid loading in male-donor-derived MDMs. Detailed lipid trafficking studies demonstrated that both estrogen and progesterone altered macrophage uptake and/or processing of modified LDL.

CONCLUSIONS

Physiological levels of estrogen and progesterone are associated with a female-sex-specific reduction in human macrophage lipid loading, which is consistent with an atheroprotective effect.

Folic acid improves arterial endothelial function in adults with hyperhomocystinemia

OBJECTIVES

To evaluate whether oral folic acid supplementation might improve endothelial function in the arteries of asymptomatic adults with hyperhomocystinemia.

BACKGROUND

Hyperhomocystinemia is an independent risk factor for endothelial dysfunction and occlusive vascular disease. Folic acid supplementation can lower homocystine levels in subjects with hyperhomocystinemia; however, the effect of this on arterial physiology is not known.

METHODS

Adults subjects were recruited from a community-based atherosclerosis study on healthy volunteers aged 40 to 70 years who had no history of hypertension, diabetes mellitus, hyperlipidemia, ischemic heart disease or family history of premature atherosclerosis (n = 89). Seventeen subjects (aged 54 +/- 10 years, 15 male) with fasting total homocystine levels above 75th percentile (mean, 9.8 +/- 2.8 micromol/liter) consented to participate in a double-blind, randomized, placebo-controlled and crossover trial; each subject received oral folic acid (10 mg/day) and placebo for 8 weeks, each separated by a washout period of four weeks. Flow-mediated endothelium-dependent dilation (percent increase in diameter) of the brachial artery was assessed by high resolution ultrasound, before and after folic acid or placebo supplementation.

RESULTS

Compared with placebo, folic acid supplementation resulted in higher serum folate levels (66.2 +/- 7.0 vs. 29.7 +/- 14.8 nmol/liter; p < 0.001), lower total plasma homocystine levels (8.1 +/- 3.1 vs. 9.5 +/- 2.5 micromol/liter, p = 0.03) and significant improvement in endothelium-dependent dilation (8.2 +/- 1.6% vs. 6 +/- 1.3%, p < 0.001). Endothelium-independent responses to nitroglycerin were unchanged. No adverse events were observed.

CONCLUSION

Folic acid supplementation improves arterial endothelial function in adults with relative hyperhomocystinemia, with potentially beneficial effects on the atherosclerotic process.

Myocarditis and cardiomyopathy associated with clozapine

BACKGROUND

Clozapine is effective for resistant schizophrenia. After two sudden deaths in physically well young men soon after starting clozapine, we investigated the cardiovascular complications for this drug.

METHODS

From January, 1993, to March, 1999, 8000 patients started clozapine treatment in Australia, and were registered with a mandatory monitoring service. We identified cases of myocarditis and cardiomyopathy from voluntary reports to the Australian Adverse Drug Reaction Committee and sought details of the relevant diagnostic studies, necropsies that had been done in suspicious cases, or both.

FINDINGS

23 cases (20 men, three women, mean age 36 years [SD 9]) were identified: 15 of myocarditis and eight of cardiomyopathy associated with clozapine treatment. Six patients died. All cases of myocarditis (five deaths) occurred within 3 weeks of starting clozapine. Cardiomyopathy (one death) was diagnosed up to 36 months after clozapine was started. Necropsy results showed mainly eosinophilic infiltrates with myocytolysis, consistent with an acute drug reaction.

INTERPRETATION

Clozapine therapy may be associated with potentially fatal myocarditis and cardiomyopathy in physically healthy young adults with schizophrenia.

Right ventricular dysfunction in congenitally corrected transposition of the great arteries

Although right ventricular (RV) dysfunction is an important complication in subjects with congenitally corrected transposition of the great arteries, its pathogenesis is poorly understood. We assessed the role of RV myocardial perfusion and found perfusion defects at rest in all 20 patients, involving 4.6 +/- 2.3 of a total of 12 segments; the extent of the resting perfusion defects correlated inversely with the RV ejection fraction.

Detection of presymptomatic atherosclerosis: a current perspective

Atherosclerosis, the pathological process underlying myocardial infarction, stroke and other occlusive vascular disease, is the major cause of death in the Western world. The development of techniques to accurately and reproducibly detect and measure the early changes of atherosclerosis and/or to identify subjects at highest cardiovascular risk may aid in the development of prevention strategies and facilitate a decrease in morbidity and mortality from atherosclerosis. Increasing understanding of the pathophysiology of early atherosclerosis has allowed the development of a number of potential methods for the assessment of the early stages of atherosclerosis in humans. These include techniques for assessing early structural changes in the coronary arteries with electron-beam computed tomography and magnetic resonance imaging. External vascular ultrasound has also been used to image other circulations as a surrogate marker for coronary atherosclerosis, e.g. the measurement of carotid artery intima-media thickness. Early functional changes of atherosclerosis have also been described many years before the development of structural changes. A number of techniques have been developed to measure endothelial dysfunction, one of the earliest changes of atherosclerosis, including non-invasive measurement of endothelial function using external vascular ultrasound. A variety of serum markers have also been described, and may be useful markers of atherosclerosis. We discuss some of the more promising techniques for the detection of early, presymptomatic atherosclerosis.

Lack of antioxidant activity of the antiatherogenic compound L-arginine

L-Arginine, the physiologic substrate of nitric oxide synthase, has antiatherogenic properties in animal models of atherosclerosis, and improves endothelial function in hypercholesterolemic humans. Some of these effects may be mediated by increased production of nitric oxide; however, some investigators have postulated a direct antioxidant action related to its aminoguanidine moiety. We aimed therefore, to assess the antioxidant properties of L-arginine. The antioxidant properties of 200 microM L-arginine. 200 microM D-arginine and 200 microM L-glutamate were compared with the powerful antioxidant ascorbate and a control (phosphate-buffered saline). Compounds were tested using four in vitro methods: (1) the Esterbauer technique (which tests the ability of the compounds to scavenge free radicals or chelate transition metals); (2) the effect on the autoxidation of ascorbate; (3) anti-tocopherol mediated peroxidation (which tests the compound's ability to synergize with alpha-tocopherol to prevent mild chemically induced LDL oxidation); and (4) the ability of the compounds to attenuate alpha-tocopherol radical in micellular emulsions (TRAA). The above methods were repeated using the metabolites of the test compounds after incubation with human endothelial cells. Ex vivo studies were then carried out by measuring levels of lipid peroxide production (using HPLC with UV and chemiluminescence detection) in three healthy volunteers before and 2 h after a single 7-g oral dose of L-arginine. By the Esterbauer technique, L-arginine increased lag time by 45% compared to control, as did D-arginine by 50%; L-glutamate had no effect and ascorbate increased lag time by 325%. Neither L-arginine, D-arginine or L-glutamate had significant effects on the autoxidation of ascorbate or anti-tocopherol mediated peroxidation. By the TRAA method, L-arginine had a small effect on preventing the decay of tocopherol. The results were similar for the studies of the compound's metabolites. In ex vivo studies, no changes were seen in lipid peroxide levels following acute dosage with L-arginine. L-Arginine has only weak and non-specific antioxidant effects, suggesting that its major cardioprotective benefits occur through other mechanisms, such as via the nitric oxide pathway.

Vascular risk factors correlate to the extent as well as the severity of coronary atherosclerosis

BACKGROUND

Because most acute coronary events result from thrombosis at sites of minor plaque, the extent of non-obstructive coronary artery disease (CAD), rather than simply the number of severe stenoses, might be clinically relevant.

OBJECTIVE

To examine the relationship between vascular risk factors and a novel extent score for CAD that measures the percentage of the coronary tree involved with atheromatous plaque, as judged by coronary angiography.

METHODS

We assessed the extent and severity of CAD and the presence of vascular risk factors of 429 consecutive eligible patients (296 men, aged 61 +/- 11 years) who presented for elective coronary angiography. Detailed analyses of lipid levels were performed for 126 subjects.

RESULTS

The mean extent score was 54 (range 0-100). The presence of diabetes (P < 0.001), current or former smoking (P < 0.005) and a history of hypertension (P < 0.001) were all strongly associated with the CAD extent score, as was severity of disease. For the 283 patients with one or no severe stenosis, diabetes was associated with a greater extent score (57 versus 41%, P < 0.005), as was smoking (49 versus 34%, P < 0.005). For the 126 patients with detailed data on lipid levels, extent of coronary artery disease was independently correlated to age (P < 0.005), male sex (P < 0.05), presence of diabetes (P < 0.05), hypertension (P < 0.05), level of lipoprotein (a) (P < 0.005) and low-density:high-density lipoprotein ratio (P < 0.01) in multivariable analysis.

CONCLUSIONS

Extent of CAD, as well as its severity, is significantly associated with traditional vascular risk factors. Because most acute coronary events occur at sites of minor plaque, this might explain the mechanism whereby risk factors confer adverse prognostic significance.

Westernization of Chinese adults and increased subclinical atherosclerosis

Cardiovascular event rates are much lower in China compared with developed countries. "Westernization" of diet and lifestyle in the Chinese, however, may lead to an increased prevalence of atherosclerosis-related diseases. Because carotid intima-media thickness (IMT) is a marker of subclinical atherosclerosis, we examined IMT and vascular risk profile in community-based groups of rural Chinese, Westernized urban Chinese, and urban whites. Mean IMT of the common carotid artery was measured in 348 healthy adults, aged 42+/-13 years (range 21 to 71 years); 116 subjects from rural China, 116 urban Chinese subjects living in Hong Kong or in Australia, and 116 urban Caucasians living in Australia. These 3 groups were matched for age, sex, and cigarette smoke exposure. Urban Chinese subjects had slightly better risk factor profile (higher HDL-cholesterol and lower blood pressure) compared with rural Chinese subjects. Despite this, however, the mean IMT was lowest in rural Chinese (0.50+/-0.10 mm), intermediate in urban Chinese (0.56+/-0.12 mm), and highest in urban whites (0.64+/-0.13 mm) (P<0.001 for comparisons between all groups). These differences in IMT were not altered after adjustment for the major traditional cardiovascular risk factors (serum lipids, smoking, and blood pressure or for body mass index). The influence of vascular risk factors on atherosclerosis between urban versus rural Chinese subjects was studied by multivariate regression models and by comparing the steepness of regression slopes between risk factors and IMT in the subject groups. The effects of smoking, HDL-cholesterol, and triglycerides on IMT were significantly greater in the urban compared with the rural Chinese (P<0.01). These data suggest that Westernization of Chinese subjects is associated with greater susceptibility to the pro-atherogenic effects of traditional vascular risk factors, such as lipids and smoking, and with evidence of increased IMT as a marker of subclinical atherosclerosis.

Intermittent hypoxaemia without orthodeoxia due to right-to-left shunting related to an elongated aorta

An elderly woman presented with unexplained, intermittent hypoxaemia unrelated to posture. Subsequent investigations revealed intermittent and variable right-to-left interatrial shunting through a patent foramen ovale in the presence of normal pulmonary arterial and intracardiac pressures, caused by right atrial compression from a horizontal, elongated ascending aorta. Surgical closure of the foramen resulted in marked clinical improvement.

Androgen exposure increases human monocyte adhesion to vascular endothelium and endothelial cell expression of vascular cell adhesion molecule-1

BACKGROUND

Male sex is an independent risk factor for coronary artery disease. Owing to the importance of monocyte adhesion to endothelial cells in the development of atherosclerosis, we hypothesized that androgens might promote this process. We therefore studied the effects of the nonaromatizable androgen dihydrotestosterone (DHT) on human monocyte adhesion to human endothelial cells and on endothelial cell-surface expression of adhesion molecules.

METHODS AND RESULTS

Human umbilical vein endothelial cells (HUVECs) were grown to confluence in media supplemented with postmenopausal female serum, then exposed for 48 hours to either DHT (40 and 400 nmol/L), with or without the androgen receptor blocker hydroxyflutamide (HF) (4 micromol/L); HF alone; or vehicle control (ethanol 0.1%). Human monocytes obtained by elutriation were incubated for 1 hour with the HUVECs at 37 degrees C, and adhesion was measured by light microscopy. Compared with vehicle control, monocyte adhesion was increased in the androgen-treated HUVECs in a dose-dependent manner (116+/-6% and 128+/-3% for DHT 40 and 400 nmol/L respectively; P<0.001). HF blocked this increase (P>/=0.3 compared with control). Surface expression of endothelial cell adhesion molecules was measured by ELISA and revealed an increased expression of vascular cell adhesion molecule-1 (VCAM-1) in the DHT-treated HUVECs (125+/-5% versus 100+/-4% in controls; P=0.002), an effect also antagonized by HF (P>/=0.3 compared with controls). Furthermore, the DHT-related increase in adhesion was completely blocked by coincubation with anti-VCAM-1 antibody. Comparable results were obtained in arterial endothelial cells and in endothelium stimulated with the cytokine tumor necrosis factor-alpha.

CONCLUSIONS

Androgen exposure is associated with increased human monocyte adhesion to endothelial cells, a proatherogenic effect mediated at least in part by an increased endothelial cell-surface expression of VCAM-1.

Arterial endothelial dysfunction related to passive smoking is potentially reversible in healthy young adults

BACKGROUND

Passive smoking is associated with early arterial damage, but the potential for reversibility of this damage is unknown.

OBJECTIVE

To assess the reversibility of arterial endothelial dysfunction, a key marker of early atherosclerosis.

DESIGN

Cross-sectional study.

SETTING

Academic medical center.

PARTICIPANTS

60 healthy persons 15 to 39 years of age: 20 with no exposure to active or passive smoking, 20 nonsmoking passive smokers (exposure to environmental tobacco smoke for > or = 1 hour per day for > or = 2 years), and 20 former passive smokers.

MEASUREMENTS

Arterial endothelial function measured by noninvasive ultrasonography.

RESULTS

Endothelium-dependent dilatation was significantly better in former passive smokers (5.1% +/- 4.1% [range, -1.2% to 15.6%]) than in current passive smokers (2.3% +/- 2.1% [range, -0.2% to 6.7%]) (P = 0.01), although both groups were significantly impaired compared with nonsmoking controls (8.9% +/- 3.2% [range, 2.1% to 16.7%]) (P < or = 0.01 for both comparisons).

CONCLUSIONS

In healthy young adults, arterial endothelial dysfunction related to passive smoking seems to be partially reversible.