Chinese adults are less susceptible than whites to age-related endothelial dysfunction

Plant-Based Nutrition: Exploring Health Benefits for Atherosclerosis, Chronic Diseases, and Metabolic Syndrome-A Comprehensive Review

Atherosclerosis, chronic non-communicable diseases, and metabolic syndrome are highly interconnected and collectively contribute to global health concerns that reduce life expectancy and quality of life. These conditions arise from multiple risk factors, including inflammation, insulin resistance, impaired blood lipid profile, endothelial dysfunction, and increased cardiovascular risk. Adopting a plant-based diet has gained popularity as a viable alternative to promote health and mitigate the incidence of, and risk factors associated with, these three health conditions. Understanding the potential benefits of a plant-based diet for human health is crucial, particularly in the face of the rising prevalence of chronic diseases like diabetes, hypertension, dyslipidemia, atherosclerosis, and cancer. Thus, this review focused on the plausible advantages of consuming a type of food pattern for the prevention and/or treatment of chronic diseases, emphasizing the dietary aspects that contribute to these conditions and the evidence supporting the benefits of a plant-based diet for human health. To facilitate a more in-depth analysis, we present separate evidence for each of these three concepts, acknowledging their intrinsic connection while providing a specific focus on each one. This review underscores the potential of a plant-based diet to target the underlying causes of these chronic diseases and enhance health outcomes for individuals and populations.

A Potential Strategy for Atherosclerosis Prevention in Modernizing China - Hyperhomocysteinemia, MTHFR C677T Polymorphism and Air Pollution (PM2.5) on Atherogenesis in Chinese Adults

BACKGROUND

Atherosclerosis is one of the most important global health hazards and air pollution (AP, PM2.5) has been implicated. In addition to traditional risk factors hyperhomocysteinemia (HC) has been recognized in many parts of China related to risk of stroke.

METHODS

To evaluate the impact of HC (homocysteine >14μmol/l) and PM2.5 air pollution on atherogenesis in modernizing China, we studied 756 asymptomatic Chinese in China from 1998-2007. PM2.5 exposure, HC, folate, and methylenetetrahydrofolate reductase (MTHFR) C/T genotype were evaluated. Brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) were measured by ultrasound. Locations were categorized as zones 1, 2 and 3, with increasing PM2.5 exposure.

RESULTS

HC was higher (19.4±13.1 and 27.1±25.1μmol/l) in high PM2.5-polluted zones 2 and 3 than in zone 1 (9.7±4.5μmol/l, p<0.0015). The top HC tertile was characterized by lower folate and vitamin B12, but a higher proportion of the MTHFR TT genotype, Metabolic Syndrome (MS) and PM2.5 level (p=0.0018). FMD was significantly lower (7.3±2.3%) and carotid IMT thicker (0.63±0.12mm) in the top HC tertile, compared with low HC tertile (8.4±2.5%, p<0.0001; 0.57±0.1mm, p<0.0001 respectively). Similar differences in FMD and IMT were seen in zones 2 and 3, compared with zone 1 (p<0.0001). On multivariate regression, HC was related to male gender (beta=0.106, p=0.021), MTHFR-TT (beta=0.935, p<0.0001), locations (beta=0.230, p<0.0001) and folate-MTHFR interaction (beta=-0.566, p<0.0001). FMD was related to age (beta= -0.221; p<0.0001), male gender (beta= -0.194, p=0.001) PM2.5 and location (beta=-0.285 to -0.303, p<0.0001). Carotid IMT was related to PM2.5 (beta=0.173, p<0.0001), HC (0.122, p=0.006) but not to MTHFR or location, independent of age, gender, MS, and LDL-C. No significant HC-PM2.5 interaction effect on FMD and IMT was observed.

CONCLUSION

HC and PM2.5 pollution but not MTHFR genotype were both related to carotid IMT, independent of other traditional risk factors. This has potential implications in dietary and AP strategies for atherosclerosis prevention in China.

The Different Impact of PM2.5 on Atherogenesis in Overseas vs. Native Chinese in the CATHAY Study

Air pollution (PM2.5) has been associated with cardiovascular disease (CVD) globally and with early atherosclerosis surrogate markers in modernized China. A sizeable number of Chinese have migrated overseas, with an increase in their vulnerability to CVD. To evaluate the impact of PM2.5 air pollution on atherogenesis in native vs. overseas Chinese, we recruited 756 asymptomatic native Chinese and 507 age- and gender-matched overseas Chinese from Sydney and San Francisco. Their cardiovascular profiles were evaluated. PM2.5 was derived from remote sensing technology; atherosclerosis surrogate markers, flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) were measured by ultrasound. The native Chinese had a higher proportion of smokers as well as higher blood pressure, glucose, metabolic syndrome and PM2.5 exposure (p < 0.001), but lower lipids and folate than the overseas Chinese (p < 0.0001). Carotid IMT was lower in the native Chinese (p < 0.0001), but the other vascular parameters were similar. A multivariate regression revealed that FMD in the native Chinese was related to the male gender, age and location; in the overseas Chinese, it was related to age, but not to PM2.5. Carotid IMT in the native Chinese was related to PM2.5, independent of atherosclerotic risk factors and location (R2 = 0.384, F = 34.5, p < 0.0001) whereas in the overseas Chinese, IMT was related to the male gender and age, but not to PM2.5 or overseas location (R2 = 0.282, F = 19.7, p < 0.0001). PM2.5 had a greater impact on atherogenesis in the native Chinese, independent of traditional risk factors, with implications for preventive strategies.

The impact of age on vascular smooth muscle function in humans

AIM

Advanced age is associated with vascular endothelial dysfunction, characterized by reductions in the endothelium-dependent vasodilation of the conduit and resistance arteries, in part, from decreased nitric oxide bioavailability. Although vascular smooth muscle function (SMF), assessed by responsiveness to an exogenous nitric oxide donor, is typically reported to be intact, many of these studies are limited by a small sample size. Therefore, the purpose of this meta-analysis is to systematically review and determine whether vascular SMF is different between older versus young healthy individuals.

DESIGN

We conducted a systematic search of MEDLINE, Cochrane and Scopus, since their inceptions until January 2014, for articles evaluating SMF in the brachial artery and/or resistance arteries (BASMF and RASMF, respectively), as assessed by the endothelium-independent vasodilator response to exogenous nitric oxide donors in older (≥60 years) and young (<30 years) groups of healthy individuals. Meta-analyses were performed to compare the mean difference in BASMF and the standardized mean difference in RASMF between older and young groups. Subgroup analyses were performed to identify sources of heterogeneity.

RESULTS

Fifteen studies assessing BASMF and 20 studies assessing RASMF were included, comprising 550 older and 516 young healthy individuals. After data pooling, BASMF and RASMF were lower in older compared with the young groups (mean difference = -1.89%, P = 0.04; standardized mean difference = -0.46, P = 0.0008, respectively). Significant heterogeneity was observed in the BASMF (I2 = 74%, P < 0.00001) and the RASMF (I2 = 57%, P = 0.0008) meta-analyses. Subgroup analyses revealed that studies with (predominantly) men showed similar SMF responses between the older and the young groups.

CONCLUSION

On the basis of the current published studies, vascular SMF is reduced in conduit and resistance arteries of otherwise healthy older individuals, particularly in women.

Effect of aging on human circulatory system in normotensive healthy subjects

Aging is associated with degenerative changes in cardiac and endothelial function (EF). This study was done to assess whether age-related changes take place on EF, carotid intima-media thickness (IMT), blood pressure (BP), and echocardiographic measurements. All volunteers were healthy normotensive healthy subjects. They were divided into three groups. Group 1, young adults: < 40 years old; Group 2, middle age: between 40 and 60 years old; Group 3, elderly: > 60 years old. High-frequency vascular ultrasound was used to assess the baseline brachial artery dimension and flow velocity after reactive hyperemia. The carotid IMT and echocardiographic measurements including Doppler variables were recorded in all subjects. Systolic BP, left ventricular mass, and left ventricular end-diastolic volume increased progressively with age (p < 0.001). Left ventricular ejection fraction decreased progressively with age (male, p = 0.034; female, p = 0.001); E/A ratio of the left ventricular flow spectrum declined with age (p < 0.001). The ultrasonic EF variables of flow increased during reactive hyperemia and IMT increased with age (p < 0.001). Our study demonstrates that BP, body weight, and ultrasonic variables changed significantly with age. The aging-associated changes provide insight into progression to atherosclerosis.

Vegan diet, subnormal vitamin B-12 status and cardiovascular health

Vegetarian diets have been associated with atherosclerosis protection, with healthier atherosclerosis risk profiles, as well as lower prevalence of, and mortality from, ischemic heart disease and stroke. However, there are few data concerning the possible cardiovascular effects of a vegan diet (with no meat, dairy or egg products). Vitamin B-12 deficiency is highly prevalent in vegetarians; this can be partially alleviated by taking dairy/egg products in lact-ovo-vegetarians. However, metabolic vitamin B-12 deficiency is highly prevalent in vegetarians in Australia, Germany, Italy and Austria, and in vegans (80%) in Hong Kong and India, where vegans rarely take vitamin B-12 fortified food or vitamin B-12 supplements. Similar deficiencies exist in northern Chinese rural communities consuming inadequate meat, egg or dairy products due to poverty or dietary habits. Vascular studies have demonstrated impaired arterial endothelial function and increased carotid intima-media thickness as atherosclerosis surrogates in such metabolic vitamin B-12 deficient populations, but not in lactovegetarians in China. Vitamin B-12 supplementation has a favourable impact on these vascular surrogates in Hong Kong vegans and in underprivileged communities in northern rural China. Regular monitoring of vitamin B-12 status is thus potentially beneficial for early detection and treatment of metabolic vitamin B-12 deficiency in vegans, and possibly for prevention of atherosclerosis-related diseases.

Impact of acute exercise on brachial artery flow-mediated dilatation in young healthy people

Background

Although chronic effects of exercise on endothelial function are established, the impact of acute exercise on flow-mediated dilatation (FMD) of brachial artery has not been elucidated yet.

Methods

Eighty-six young healthy volunteers were prospectively enrolled from January 2011 to December 2011. The subjects completed FMD tests at rest and immediately after treadmill exercise test. Primary outcome was the impact of acute exercise on FMD, measured by the difference of FMD before and after exercise. Secondary outcomes were the relationship of gender and exercise habit with FMD.

Results

Seventy-four subjects who met the eligibility criteria were included for analysis. Thirty-five (47.3%) were male, and the mean age was 22.7±2.7 years. FMD was reduced after exercise (8.98±4.69 to 7.51±4.03%; P=0.017) and the reduction was found in female group (10.36±5.26 to 7.62±3.71%; P=0.002) but not in male group. Post-exercise FMD was significantly impaired in subjects who did not exercise regularly (6.92±3.13% versus 8.95±5.33%; P=0.003). The decrease of FMD after exercise was greater in female group (−2.75±5.28% versus 0.27±3.24%; P=0.003) and was associated with exercise habit (β=2.532; P=0.027).

Conclusions

In healthy young subjects, FMD was reduced after a bout of acute exercise. The impact of acute exercise showed significant differences according to gender and exercise habit. FMD impairment after acute exercise was observed in females and subjects without regular exercise.

Relation of omega-3 fatty acid and dietary fish intake with brachial artery flow-mediated vasodilation in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

The relation between dietary fish intake and brachial artery measures, including brachial artery flow-mediated dilation (FMD), has not been well established across sex and racial-ethnic groups.

OBJECTIVE

We hypothesized that consumption of nonfried fish and plasma phospholipid measures of long-chain omega-3 (n-3) fatty acids would be positively associated with larger FMD in men and women across racial-ethnic groups.

DESIGN

We investigated cross-sectional associations of brachial artery measures with fish intake (ascertained with a food-frequency questionnaire) and plasma phospholipid omega-3 concentrations in 3045 adults, aged 45-84 y, who were free of clinical cardiovascular disease.

RESULTS

In overall multivariate-adjusted analyses, there were no significant associations between fish intake or any brachial artery measures. However, when stratified by sex, there was an association between the highest quartile of nonfried fish consumption and a 0.10-mm lower (1 SD) brachial artery diameter in men (P = 0.01) and a 0.27% smaller FMD in women (P = 0.02) compared with the lowest quartile of nonfried fish intake in each respective sex strata. When stratified by race-ethnicity and race-ethnicity by sex, additional heterogeneity was noted, but results were difficult to interpret because of small sample sizes. Plasma phospholipid omega-3 concentrations showed a similar directionality of association with brachial artery measures observed for nonfried fish consumption, although statistical significance was not achieved in fully adjusted models.

CONCLUSION

This study indicates that the association between nonfried fish intake and baseline brachial artery size varies by sex, with suggestive evidence of sex differences in the association between nonfried fish intake and FMD.

Outcome of coronary plaque burden: a 10-year follow-up of aggressive medical management

Background

The effect of aggressive medical therapy on quantitative coronary plaque burden is not generally known, especially in ethnic Chinese.

Aims

We reasoned that Cardiac CT could conveniently quantify early coronary atherosclerosis in our patient population, and hypothesized that serial observation could differentiate the efficacy of aggressive medical therapy regarding progression and regression of the atherosclerotic process, as well as evaluating the additional impact of life-style modification and the relative effects of the application of statin therapy.

Methods

We employed a standardized Cardiac CT protocol to serially scan 113 westernized Hong Kong Chinese individuals (64 men and 49 women) with Chest Pain and positive coronary risk factors. In all cases included for this serial investigation, subsequent evaluation showed no significantly-obstructive coronary disease by functional studies and angiography. After stringent risk factor modification, including aggressive statin therapy to achieve LDL-cholesterol lowering conforming to N.C.E.P. ATP III guidelines, serial CT scans were performed 1-12 years apart for changes in coronary artery calcification (CAC), using the Agatston Score (AS) for quantification.

Results

At baseline, the mean AS was 1413.6 for males (mean age 54.4 years) and 2293.3 for females (mean age 62.4 years). The average increase of AS in the entire study population was 24% per year, contrasting with 16.4% per year on strict risk factor modification plus statin therapy, as opposed to 33.2% per year for historical control patients (p < 0.001). Additionally, 20.4% of the 113 patients demonstrated decreasing calcium scores. Medical therapy also yielded a remarkably low adverse event rate during the follow-up period --- 2 deaths, 2 strokes and only 1 case requiring PCI.

Conclusions

This study revealed that aggressive medical therapy can positively influence coronary plaque aiding in serial regression of calcium scores.

Endothelial Dysfunction in Normotensive Chinese with a Family History of Essential Hypertension

Endothelial dysfunction is seen in patients with essential hypertension. However, it is still debated whether impaired endothelial function occurs before the development of hypertension. The aim of our study was to investigate whether endothelial dysfunction occurs in genetically vulnerable normotensive Chinese, and whether the endothelial dysfunction is worse as essential hypertension progresses. Endothelial function was assessed by high-resolution vascular ultrasound (7.5 MHz). The diameters of brachial arteries were measured at rest, during reactive hyperemia, and after sublingual administration of nitroglycerine (GTN) in 58 subjects with a mean age of 46.7 +/- 10.1 years. Among them, 18 patients had essential hypertension (Group 2), 20 normotensive subjects had a family history of hypertension (Group 3), and 20 normotensive subjects without a family history of cardiovascular diseases served as controls (Group 1). There was no difference in age among the three groups (Group 1: 46.5 +/- 10.5 versus Group 2: 46.7 +/- 9.5 versus Group 3: 44.50 +/- 11.21 years, P = NS). Flow-mediated dilatation of brachial arteries was significantly reduced in Group 2 and 3 as compared with Group 1 (Group 1: 13.2 +/- 5.9% versus Group 2: 8.0 +/- 3.6 versus Group 3: 4.86 +/- 3.5, both p < .01). On the other hand, nonflow mediated vasodilatation in response to GTN did not differ among the three groups. Endothelium-dependent vasodilatation is impaired not only in normotensive subjects with a family history of hypertension, but also becomes worse in the hypertensive patients.

Evaluation of endothelial function in hypertensive elderly patients by high-resolution ultrasonography

BACKGROUND

Multiple investigations, both in experimental models and in middle-aged patients with essential hypertension, demonstrate impaired endothelium-dependent vasodilatation.

HYPOTHESIS

We attempted to determine whether hypertension still exerts additional negative effect on endothelial function of large arteries in hypertensive elderly patients who may already be affected by endothelial dysfunction due to aging.

METHODS

We compared 13 elderly patients with hypertension [69 +/- 9 years, (mean +/- standard deviation)] with 13 matched healthy elderly subjects (72 +/- 6 years) as controls. Using high-resolution vascular ultrasound, we measured brachial artery responses to reactive hyperemia (with increased flow causing endothelium-dependent dilatation) and sublingual nitroglycerin (causing endothelium-independent dilatation).

RESULTS

Flow-mediated dilatation correlated inversely with age (r = -0.60, p = 0.03) in the controls. Flow-mediated dilatation was significantly impaired in hypertensive elderly patients (6.7 +/- 3.3 vs. 13.3 +/- 1.8% in controls, p < 0.0001). No significant difference could found in nitroglycerin-induced dilatation between controls (12.1 +/- 4.9%) and hypertensive elderly patients (10.2 +/- 6.8%, p = 0.5). On multivariate analysis, flow-mediated dilatation in hypertensive elderly patients was inversely related to aging (r = -0.37, p = 0.04) and mean blood pressure (r = -0.57, p = 0.03).

CONCLUSIONS

Our study showed decreased flow-mediated dilatation with aging even in the healthy controls, and further decline in flow-mediated dilatation in hypertensive elderly patients compared with controls. This impairment of flow-mediated dilatation in hypertensive elderly patients was related to age and mean blood pressure, indicating that aging and hypertension may independently impair endothelial function in the brachial artery of these patients.

Brachial artery ultrasound: a noninvasive tool in the assessment of triglyceride-rich lipoproteins

In recent years, endothelial dysfunction has been identified as an early feature of atherosclerosis. Endothelial function can be measured noninvasively by using brachial artery ultrasound. A variety of factors associated with atherosclerosis also impair endothelial function. Some of these factors are lipoproteins such as various forms of low-density lipoproteins, postprandial chylomicron remnants, fasting triglyceride-rich particles, and free fatty acids. A high-fat diet also has an adverse effect on endothelial function. Several interventions can improve endothelial function and, at the same time, reduce cardiovascular events. Measuring endothelial function may eventually serve as a useful index to determine an individual's risk for coronary artery disease.

Does regular consumption of green tea influence expression of vascular endothelial growth factor and its receptor in aged rat erectile tissue? Possible implications for vasculogenic erectile dysfunction progression

Erectile dysfunction (ED) is a highly prevalent disease affecting millions of men worldwide with a tendency for widespread increase. ED is now considered an early manifestation of atherosclerosis and, consequently, a precursor of systemic vascular disease. Atherosclerosis and ED share potentially modifiable risk factors, as smoking or high-fat food intake, but it is unclear how regular consumption of anti-oxidant rich drinks, which exhibit recognised anti-atherosclerotic features, affects ED progression. The objective of this study was to evaluate the modulating effects of chronic consumption of catechin-rich beverages on the vascular structure of the rat corpus cavernosum, and how this could contribute to delay or prevention of the onset of ED. Male Wistar rats aged 12 months were treated with green tea (GT) or a green tea extract solution (GTE) as the only liquid source for 6 months. Consumption of GT and GTE led to decreased plasma androgen levels without any significant change in plasma lipid levels. A reduction in corpus cavernosum intracellular storage of lipids, associated with decreased expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR2 in endothelial cells, was observed. Taken together, these results suggest diminished atherosclerotic progression in cavernous tissue. However, functional studies will be necessary to elucidate if catechin-rich beverages are useful compounds in the prevention of deleterious vascular events associated with ED. It was also demonstrated that regular consumption of catechins reduces atherosclerotic progression and mortality due to cardiovascular disease. The results reported here suggest diminished atherosclerotic progression in cavernous tissue in aged rats following chronic ingestion of catechin-rich beverages.

Endothelial function and urine albumin levels among asymptomatic Mexican-Americans and non-Hispanic whites

Background-

Mexican-Americans (MA) exhibit increases in various cardiovascular disease (CVD) risk factors compared to non-Hispanic Whites (NHW), yet are reported to have lower CVD mortality rates. Our aim was to help explain this apparent paradox by evaluating endothelial function and urine albumin levels in MA and NHW.

Methods-

One hundred-five MA and 100 NHW adults were studied by brachial artery flow-mediated dilatation (FMD), blood and urine tests. Participants were studied by ultrasound-determined brachial artery flow-mediated dilatation (FMD), blood and urine tests, at a single visit.

Results-

Despite higher BMI and triglycerides in MA, MA demonstrated higher FMD than did NHW (9.1 ± 7.3% vs. 7.1 ± 6.3%, p < 0.04). Among MA, urinary albumin was consistently lower in participants with FMD ≥ 7% FMD versus < 7% FMD (p < 0.006). In multivariate analyses in MA men, urinary albumin was inversely related to FMD (r = -0.26, p < 0.05), as were BMI and systolic blood pressure. In MA women, urinary albumin:creatinine ratio was an independent inverse predictor of FMD (p < 0.05 ).

Conclusion-

To our knowledge, this is the first study to analyze, in asymptomatic adults, the relation of MA and NHW ethnicity to FMD and urine albumin levels. The findings confirm ethnic differences in these important subclinical CVD measures.

Greater adverse effects of cholesterol and diabetes on carotid intima-media thickness in South Asian Indians: comparison of risk factor-IMT associations in two population-based surveys

Asian Indians appear particularly susceptible to coronary heart disease compared with other ethnic groups. We compared the effects of vascular risk factors on carotid intima-media thickness (IMT) in a population of South Asians from Andhra Pradesh, India with a population of Caucasians from Perth, Australia. Cardiovascular risk factors and ultrasound-assessed carotid IMT were measured in randomly selected adults from two villages in rural India (n=303) and compared to those for randomly sampled adults from Australia (n=1111). Regression models with interaction terms were used to compare the strengths of associations between risk factors and carotid IMT, in these two populations. There were stronger associations of cholesterol (p for interaction=0.009) and diabetes (p=0.04) with carotid IMT in the Indian compared to the Australian population. Also, while increasing HDL-cholesterol was associated with decreasing carotid IMT in the Australian population the reverse was true for the Indian population (p<0.001). The associations with IMT of blood pressure, triglycerides, age, HDL to total cholesterol ratio, glucose, BMI, waist, waist to hip ratio and smoking were not different between the populations. Greater adverse effects of total cholesterol and diabetes on atherosclerosis and no protective effect of HDL-cholesterol amongst Asian Indians provide a novel possible explanation for observed excess rates of cardiovascular disease amongst these populations.

All teas are not created equal: the Chinese green tea and cardiovascular health

Tea is one of the most widely consumed beverages in the world, next only to water. It can be categorized into three types, depending on the level of fermentation, i.e., green (unfermented), oolong (partially fermented) and black (fermented) tea. In general, green tea has been found to be superior to black tea in terms of antioxidant activity owing to the higher content of (-)-epigallocatechin gallate. The processes used in the manufacture of black tea are known to decrease levels of the monometric catechins to a much greater extent than the less severe conditions applied to other teas. The cardioprotective effect of flavonoids from green tea can be attributed to not only antioxidant, antithrombogenic and anti-inflammatory properties but also improvement of coronary flow velocity reserve. In this article, I will discuss the effects of green tea on atherosclerosis, coronary heart disease, hypertension, diabetes, metabolic syndrome and obesity, and, finally, its comparison with black tea.

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening

OBJECTIVE

We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children.

DESIGN

Case-control comparison.

SUBJECTS

A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25+/-3) aged 9-12 y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community.

MEASUREMENTS

The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist-hip ratio (WHR), blood pressures, blood lipids, insulin and glucose.

RESULTS

The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6+/-2.3 vs 9.7+/-3.0%, P<0.0001) and increased carotid IMT (0.49+/-0.04 mm vs 0.45+/-0.04 mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis.

CONCLUSION

Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Effect of atorvastatin on impaired vascular function in healthy old men

OBJECTIVE

This study was initiated to examine the effect of cholesterol-lowering therapy with 40 mg atorvastatin on vascular function in healthy old and young men.

METHODS

We selected healthy normolipidaemic, elderly subjects (n = 8, mean age 80.1 years) and young subjects (n = 7, mean age 21.8 years). All had a normal electrocardiograph and blood pressure, and signs or symptoms of cardiovascular disease were absent. The subjects were studied for 2 days, with 6 weeks of atorvastatin treatment in between. Forearm blood flow (FBF) was measured by computerized venous occlusion plethysmography upon intra-arterial infusion of acetylcholine (ACh; 30 and 90 ng/kg/min) and 5-hydroxytryptamine (5-HT; 0.3 and 0.9 ng/kg/min) as endothelium-dependent vasodilators, and sodium nitroprusside (SNP; 30 and 90 ng/kg/min) as an endothelium-independent vasodilator.

RESULTS

At baseline, the mean absolute FBF in the elderly was 2.6 mL/min/100 mL and in the young 4.3 mL/min/100 mL tissue (P = 0.01). The mean serum total cholesterol levels were 5.2 and 3.8 mmol/L, respectively (P = 0.007). The endothelium-dependent vasodilatation induced by ACh and 5-HT was significantly lower in the elderly compared with the young (both P < 0.01), whereas the endothelium-independent vasodilatation induced by SNP was not significantly lower in the elderly compared with the young. Atorvastatin treatment decreased the serum total cholesterol level with a mean of 38 and 28% in the elderly and the young, respectively (P < 0.001). Impaired endothelium-dependent vasodilatation, however, was not modified (P > 0.65).

CONCLUSIONS

Healthy old men have an impaired endothelium-dependent vascular response but this impairment is not restored by treatment with atorvastatin.

Deleterious Impact of “High Normal” Glucose Levels and Other Metabolic Syndrome Components on Arterial Endothelial Function and Intima-Media Thickness in Apparently Healthy Chinese Subjects: The CATHAY Study

Objective— Endothelial vasodilator dysfunction and carotid intima-media thickening are useful surrogate markers of cardiovascular disease, a major cause of morbidity and mortality in type 2 diabetic patients. However, because most studies reporting the relationships between endothelial function, intima-media thickness (IMT), and hyperglycemia have compared diabetic patients with healthy controls, we report their relationship with glycemia as a continuum.

Methods and Results— Brachial artery endothelial function (flow-mediated dilatation [FMD]) and carotid IMT were measured noninvasively by high-resolution ultrasound B-mode imaging in 228 apparently healthy Chinese subjects recruited from Hong Kong and Macau. FMD and IMT were significantly associated with increasing levels of glycemia, particularly in the “high normal” glycemic range, with IMT increasing and endothelium-independent dilatation decreasing linearly across the glucose tertiles, and endothelium-dependent dilatation significantly lower in the upper glucose tertile compared with the other 2 groups ( P <0.01). Using multiple linear regression, fasting glucose level was identified as an independent predictor of each of these markers of vascular function ( P <0.004). Additionally, other conventional cardiovascular risk factors, including obesity, blood pressure, and an adverse lipid profile, were also related to levels of glycemia ( P <0.05), further contributing to impaired vascular function.

Conclusion— Increasing levels of glycemia and the coexistence of other cardiovascular risk factors in apparently healthy subjects are adversely associated with arterial endothelial dysfunction and intima-media thickening.

Age-related endothelial dysfunction : potential implications for pharmacotherapy

Aging per se is associated with abnormalities of the vascular wall linked to both structural and functional changes that can take place at the level of the extracellular matrix, the vascular smooth muscle and the endothelium of blood vessels. Endothelial dysfunction is generally defined as a decrease in the capacity of the endothelium to dilate blood vessels in response to physical and chemical stimuli. It is one of the characteristic changes that occur with age, independently of other known cardiovascular risk factors. This may account in part for the increased incidence of cardiovascular events in elderly people that can be reversed by restoring endothelial function. A better understanding of the mechanisms involved and the aetiopathogenesis of this process will help in the search for new therapeutic agents.Age-dependent alteration of endothelium-dependent relaxation seems to be a widespread phenomenon both in conductance and resistance arteries from several species. In the course of aging, there is an alteration in the equilibrium between relaxing and contracting factors released by the endothelium. Hence, there is a progressive reduction in the participation of nitric oxide and endothelium-derived hyperpolarising factor associated with increased participation of oxygen-derived free radicals and cyclo-oxygenase-derived prostanoids. Also, the endothelin-1 and angiotensin II pathways may play a role in age-related endothelial dysfunction. The use of drugs acting at different levels of these signalling cascades, including antioxidant therapy, lipid-lowering drugs and estrogens, seems to be promising.

Elevated C-reactive protein levels are associated with endothelial dysfunction in chronic cocaine users

OBJECTIVE

To examine the relationship of the serum C-reactive protein (CRP) and endothelial function and their associations with coronary artery calcification, lipid profile and cardiac changes.

METHODS

The analyses for serum lipids and CRP, echocardiography, spiral computed tomography scans and endothelial function assay were performed in 53 participants with a history of chronic cocaine use.

RESULTS

There were no statistically significant differences in demographic characteristics and drug use between CRP normal (<1.9 mg/l) and abnormal groups. The brachial artery diameter percentage changes in the third scan (immediately after deflation of cuff) and the fourth scan (90 s after deflation of cuff) were significantly associated with the CRP levels (the third: beta=-0.054, S.E.=0.027; P=0.028; the fourth: beta=-0.065, S.E.=0.026; P=0.016). The multiple regression models showed that CRP was the only significant predictor of artery diameter changes (%) in these two scans. The CRP abnormal group had more coronary artery calcification (calcium scores >5, 16.7 vs. 0%; P=0.036) and more cardiac diastolic dysfunction expressed as deceleration time >240 ms (16.7 vs. 0%; P=0.036).

CONCLUSIONS

Elevated serum CRP levels are associated with endothelial dysfunction, coronary artery calcification and cardiac diastolic dysfunction in chronic cocaine users.

Maintaining the endothelium: preventive strategies for vessel integrity

The endothelium is a diaphanous membrane, only one cell layer thick, that lines all of our blood vessels. Despite its apparent fragility, it exerts profound control over vascular tone, structure, and interaction with circulating blood elements. One of the factors that the endothelium synthesizes is nitric oxide, which is the most potent endogenous vasodilator known. In addition to its blood flow regulating effects, nitric oxide also inhibits key processes in atherosclerosis, including monocyte adherence, platelet aggregation, and proliferation of vascular smooth muscle cells. Nitric oxide synthesis is impaired, and its degradation is accelerated, in many of the conditions associated with atherosclerosis, including hypercholesterolemia. Restoration of nitric oxide synthesis and activity in these disorders can improve blood flow, relieve symptoms, and perhaps reduce the progression of atherosclerosis (part 1 of 2 parts). (c) 2000 by CHF, Inc.

Maintaining the endothelium: preventive strategies for vessel integrity

The endothelium is a diaphanous membrane, only one cell layer thick, that lines all of our blood vessels. Despite its apparent fragility, it exerts profound control over vascular tone, structure, and intersection with circulating blood elements. One of the factors that the endothelium synthesizes is nitric oxide, which is the most potent endogenous vasodilator known. In addition to its blood flow regulating effects, nitric oxide also inhibits key processes in atherosclerosis, including monocyte adherence, platelet aggregation, and proliferation of vascular smooth muscle cells. Nitric oxide synthesis is impaired, and its degradation is accelerated, in many of the conditions associated with atherosclerosis, including hypercholesterolemia. Restoration of nitric oxide synthesis and activity in these disorders can improve blood flow, relieve symptoms, and perhaps reduce the progression of atherosclerosis.(c) 2001 by CHF, Inc.

Lipoprotein (a) is associated with endothelial function in healthy postmenopausal women

BACKGROUND

Lipoprotein (a) (Lp(a)) is an independent risk factor for atherosclerotic cardiovascular disease. The atherogenic potential of Lp(a) may be by impairment of endothelial function. Objectives. We investigated the relation of Lp(a) plasma levels to endothelium dependent and independent dilatation of the brachial artery in healthy postmenopausal women.

METHODS

One hundred and five healthy postmenopausal women aged 52-67 years were included in the study. Endothelial function was assessed non-invasively by measuring percent lumen diameter change in the brachial artery after reactive hyperemia and sublingual nitroglycerine spray.

RESULTS

Flow mediated dilatation was inversely related to the plasma logLp(a) level. Mean change per unit logLp(a) increase:-2.83% (95% CI: -5.22--0.43). Elevated Lp(a) (>239 mg/l) (upper quartile) was associated with an impaired flow mediated vasodilatation (2.4%+/-1. 2) compared to Lp(a) < or =239 mg/l (5.2%+/-0.7). Adjustment for other cardiovascular risk factors did not change the magnitude of the association. Nitroglycerine-induced vasodilatation was not significantly lower in the high Lp(a) level group, compared to the group with normal levels of Lp(a) (< or =239 mg/l) (8.0+/-1.2 vs. 11.4%+/-0.8).

CONCLUSION

Elevated lipoprotein (a) levels are associated with an impaired endothelial function in healthy postmenopausal women, independent of conventional risk factors for cardiovascular disease. Since Lp(a) may be pathogenetically important for early vascular damage, elevated Lp(a) levels might contribute to the increased cardiovascular risk seen in postmenopausal women.

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.

Peripheral vascular endothelial dysfunction and apoptosis in old monkeys

To determine the effects of aging on vasoactivity in a primate model (Macaca fascicularis), 13 young male monkeys (aged 7.1+/-0.4 years) and 9 old male monkeys (aged 19.8+/-0.6 years) were chronically instrumented for measurement of left ventricular and aortic pressures and cardiac output. Total cholesterol, triglyceride, and fasting blood sugar levels were not different between the 2 groups. There were no significant differences in baseline mean aortic pressure and total peripheral resistance (TPR) in the young monkeys versus the old monkeys. TPR fell less (P<0.05) with acetylcholine (1 microg/kg) in old monkeys (-25+/-1%) than in young monkeys (-34+/-2%), whereas decreases in TPR with sodium nitroprusside were similar in old and young monkeys. There was no evidence of atherosclerosis, but apoptosis of endothelial cells was enhanced (P<0.05) in the aortas and femoral arteries, but not in the media, of the old monkeys. There was a relationship (r=0.62, P=0.013) between the incidence of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive endothelial cells and endothelial cell density in the femoral artery. The reduced endothelial cell density was also correlated (r=0.82, P<0.01) with depressed TPR responses to acetylcholine. Thus, vascular endothelial dysfunction was present in old monkeys without evidence of atherosclerosis, which may be due to endothelial apoptosis and reduced endothelial cell density.

Scanning electron microscopic analysis of endothelial cell coverage and quality in large vessels from multi-organ donors: effects of preservation on endothelial cell integrity

Endothelial cell integrity (coverage and quality) of large donor vessels is important because these vessels are used for vascular reconstructions in solid-organ transplantation. Disruption of the endothelial cell monolayer will initiate blood coagulation and may lead to thrombosis of large vessels, often resulting in the loss of the transplanted organ. Iliac arteries and veins, removed from 10 heart-beating multi-organ donors at the end of the donor procedure, were analyzed using scanning electron microscopy at three different time points of preservation. Endothelial cell coverage and quality were determined immediately after removal from the donor, after 10 h (time of transplantation) and 7 d storage in 'University of Wisconsin' cold preservation solution (UW). Endothelial cell coverage decreased during the preservation of arteries, but was maintained in veins. Storage of the veins for 7 d in plastic bags showed a decreased endothelial cell coverage compared to storage in glass vials. Early removal of the blood vessels and proper storage, free floating and in clean UW, may improve maintenance of the endothelial cell integrity. These findings may be important in order to reduce the risk of thrombosis and, consequently, organ failure after transplantation. Furthermore, vessels with maintained endothelial cell integrity after 7 d may be used for in vitro research.

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.

Effects of methionine-induced hyperhomocysteinemia on endothelium-dependent vasodilation and oxidative status in healthy adults

BACKGROUND

Homocysteine-mediated endothelial dysfunction has been proposed to occur via oxidative stress mechanisms in humans. However, there is controversy regarding the effects of homocysteine on endothelial function and oxidative status, which may in part result from age discrepancy across the studies. The present study was designed to investigate the aging effect on the relationship between endothelium-dependent vasodilation and oxidative status in methionine-induced hyperhomocysteinemia.

METHODS AND RESULTS

Plasma homocysteine, phosphatidylcholine hydroperoxide (PCOOH), P-selectin levels, and brachial artery flow-mediated vasodilation were measured at baseline and 4 hours after an oral methionine load (0.1 g/kg) in 15 younger (21 to 40 years) and 15 older (55 to 70 years) healthy adults. Homocysteine increased from 7.3+/-1.3 micromol/L at baseline to 22.7+/-5.2 micromol/L at 4 hours in younger (P<0.001) and from 7. 4+/-1.4 to 24.3+/-4.5 micromol/L in older adults (P<0.001). PCOOH levels were not significantly different between baseline and 4 hours in both groups (P=0.10 in young; P=0.14 in old). P-selectin, which is expected to increase during oxidative stress, was not changed in older (P=0.08) but decreased in younger adults (P=0.037) at 4 hours. Flow-mediated vasodilation was preserved from 13.1+/-2.1% at baseline to 13.5+/-2.8% at 4 hours in younger (P=0.49) and decreased from 12.8+/-2.4% to 8.5+/-2.8% in older adults (P<0.001).

CONCLUSIONS

The present study demonstrates that endothelial dysfunction caused by methionine-induced hyperhomocysteinemia is age-related and is mediated through impaired nitric oxide activity without change of oxidative status. Our data do not support previous hypotheses that endothelial damage by homocysteine is via oxidative stress mechanism in humans.

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.

How to assess endothelial function in human blood vessels

This brief review discusses the ways, if and when available, to examine endothelium-dependent changes diameter in human blood vessels. It stresses the problems in ensuring proper matching between arteries (and veins) from different human sources. It briefly considers the evidence in vitro supporting the role of endothelium-derived nitric oxide, hyperpolarizing factor and contracting factors (including metabolites of arachidonic acid and endothelin). It emphasizes the difficulty in extrapolating observations obtained in isolated arteries (and veins) to the intact human circulation. The overall conclusion is that the interpretations derived from animal work apply to the human vasculature.

Endothelial dysfunction in hypertension

Hypertension is an important risk factor for the development of atherosclerosis and endothelial dysfunction may be a key mechanism. The nitric oxide mediated vasodilator function of the endothelium has been widely studied as a test of endothelial integrity in patients with hypertension and impaired basal and muscarinic agonist stimulated components of nitric oxide mediated vascular tone have been found in coronary, forearm and cutaneous resistance vessels and in coronary and forearm conduit vessels. The underlying abnormalities of these changes are unknown but it is likely to be a secondary phenomenon due to increased blood pressure. However, endothelial dysfunction as assessed by response to muscarinic agonists does not occur in all patients and antihypertensive therapy so far has been mostly unable to reverse it. Although widely used the response to acetylcholine has some shortcomings and it remains to be established what parameter best reflects endothelial dysfunction. The relationship of such abnormalities to the present or future atherosclerosis needs to be defined.

Abnormalities of vascular endothelial function may contribute to increased coronary heart disease risk in UK Indian Asians

OBJECTIVE

To test the hypothesis that abnormalities of endothelial function are present in Indian Asians and may contribute to their increased coronary heart disease risk.

SETTING

Single centre in west London.

PATIENTS

26 Indian Asian and 18 European white healthy male subjects, aged 35 to 61 years recruited from general practice lists.

DESIGN

Brachial artery diameter responses to reactive hyperaemia and sublingual glyceryl trinitrate were compared using high resolution ultrasound.

RESULTS

Mean (SEM) flow mediated, endothelium dependent dilatation was reduced in Indian Asians compared with European whites, at 3.2 (0.8)% v 5.9 (1.0)%, p = 0.03. In contrast, there were no significant differences in baseline brachial arterial diameter (4.6 (0.1) v 4.6 (0.1) mm, p = 0.65) or glyceryl trinitrate induced dilatation (18.8 (1.5)% v 18.5 (1.7)%, p = 0.90) between Indian Asians and European whites, respectively. Univariate analysis showed that Indian Asian race was significantly associated with impaired flow mediated dilatation (regression coefficient = -2.8 (1.3)%, p = 0.03), and in multivariate analysis, this relation was independent of both conventional coronary heart disease risk factors and markers of insulin resistance.

CONCLUSIONS

Endothelial function is impaired in healthy UK Indian Asians compared with European whites, and the defect is not accounted for by major coronary heart disease risk factors. Endothelial function may be modulated by novel risk factors in Indian Asians.

New risk factors for coronary heart disease in Asia

The increasing prevalence of traditional atherosclerotic risk factors have been documented in Asia but the real impact on prevalence of coronary heart disease (CHD) remains unclear. Smoking, hypertension, hypercholesterolaemia, diabetes mellitus and obesity are present in only 50% of CHD. In community studies of Chinese in Hong Kong and southern mainland-China, aging, smoking and hypercholesterolaemia were found to have a less impact on endothelial function in the Chinese compared with Caucasians in London and Sydney. As endothelial dysfunction is an early event in atherogenesis, there will be a strong need to search for newer risk factors for CHD in Asia, which may become more important in many Asian countries now in the process of modernization. Recently, heterozygous hyperhomocysteinaemia (with or without folate deficiency) was found to be an independent risk factor for arterial endothelial dysfunction, and hyperhomocysteinaemia in association with smoking was a significant risk factor for premature coronary heart disease in Hong Kong Chinese. Other newer factors which have emerged include folate deficiency, low HDL-cholesterol, insulin resistance, abdominal obesity, Methylene-tetrahydrofolate Reductase and Angiotensin Converting Enzyme gene polymorphism.