Ethnic Differences in Arterial Responses and Inflammatory Markers in Afro-Caribbean and Caucasian Subjects
Arteriosclerosis, Thrombosis, and Vascular Biology
Abstract
Objective— Small vessel disease is more common in Afro-Caribbeans than Caucasians. We investigated underlying differences in metabolic, inflammatory, and vascular responses that may predispose Afro-Caribbeans to small vessel pathology.
Methods and Results— Seventy-eight Afro-Caribbeans aged 35–75 years, with no vascular disease or medications, were compared with 82 matched Caucasians for metabolic variables, fasting insulin, interleukin 6, tumor necrosis factor (TNF) α, and cytoplasmic repressor protein levels. Carotid intima media thickness (CIMT) was measured ultrasonographically. Small vessel function was assessed by measuring the absolute change from baseline in the reflectance index (RI) of the digital volume pulse during IV infusion of albuterol (5 μg/min, ΔRIALB) and glyceryl tri nitrate (5 μg/min, ΔRIGTN). Large artery elasticity was measured as the stiffness index (SI) and derived from the time to pulse wave reflection adjusted for subject height. Afro-Caribbeans had significantly higher diastolic blood pressure (80.3 versus 77.6 mm Hg; P=0.033), fasting insulin (14.0 versus 10.6 μU/mL; P=0.026), TNF-α (6.7 versus 4.3; pg/mL; P=0.001), and interleukin 6 (2.3 versus 1.5 pg/mL; P=0.036) levels compared with Caucasians. CIMT was greater (0.81±0.20 versus 0.75±0.18 mm; P=0.02) and small vessel reactivity attenuated (mean ΔRIALB 6.8±8.0% versus 12.3±8.%; P<0.0001) in Afro-Caribbeans, but their large artery elasticity (mean index of large artery stiffness 9.9 versus 9.7 m/s; P=0.48) was comparable with Caucasians. CIMT was independently associated with an index of large artery stiffness (β=0.03; P=0.002) in Caucasians but not in Afro-Caribbeans. There were independent relationships among Afro-Caribbean ethnicity, TNF-α, and insulin levels.
Conclusions— Selective impairment of small artery function may contribute to excess small vessel disease in Afro-Caribbeans.
Abstract
Small vessel disease is more common in Afro-Caribbeans. A comparison of metabolic variables, inflammatory markers, and arterial function between 78 healthy Afro-Caribbeans and 82 matched Caucasians showed higher diastolic blood pressure, fasting insulin, tumor necrosis factor α, and interleukin 6 levels in Afro-Caribbeans, which was associated with the attenuation of small, but not large, vessel function.
Epidemiological research has shown that the incidence of small vessel stroke and end-stage renal failure are high in people of African descent compared with those of Caucasian origin.1–4 Although hypertension, diabetes, and other vascular risk factors are more prevalent in people of African descent in the setting of these studies, these differences alone do not explain the disparities between the 2 ethnic groups.5–7 A possible explanation may be that clustering of metabolic risk factors within individuals is more common in people of African descent and contributes to small vessel pathology.8 Other studies suggest that there are ethnic differences in vascular function, which may predispose subjects of African descent to small vessel disease.9,10 Neither of these possibilities has been systematically investigated.
See page 2240
The precise mechanisms contributing to small vessel disease remain unknown. Studies have shown that endothelial dysfunction predicts stroke in patients without significant atheroma11,12 and that patients with small vessel disease have hyperinsulinaemia even in the absence of diabetes mellitus or obesity.13 These findings become particularly interesting in the context of studies describing attenuated NO-mediated vascular reactivity in healthy black subjects9,14 and greater correlation between insulin resistance and target organ damage in hypertensive Afro-American compared with Caucasian subjects.15 This implies that there may be relationships among metabolic factors, insulin levels, and small vessel impairment in people of African descent, which merit investigation.
We hypothesized that increased metabolic stress and differences in physiological response between large and small arteries predisposed Afro-Caribbean people to small vessel disease. We undertook a matched cohort comparison between healthy Afro-Caribbean and Caucasian subjects who did not have hypertension, diabetes mellitus, or hypercholesterolemia to investigate the differences in metabolic variables, inflammatory markers, and measures of small and large artery function.
Methods
Subjects
Ethnicity was self-defined, and only subjects with both parents and all 4 grandparents belonging to the same ethnic group were included. Subjects were recruited from patients registered at a general practice in South London (32,000 patients, 28% Afro-Caribbeans). A random sample of 800 registrants between 35 and 75 years of age was obtained using patient record numbers, and their medical records were screened for inclusion. Subjects were included if they had no history of vascular disease and were not on any medication. Those with a history of stroke, transient ischemic attacks, angina, myocardial infarction, heart failure, peripheral vascular disease, hypertension, diabetes mellitus, or hypercholesterolemia were excluded. Potentially eligible participants attended a research clinic (n=298) where eligibility was confirmed and consent obtained. If a potential subject failed to meet inclusion criteria during baseline assessment (n=109) or declined (n=27), the next person on the list who matched age, gender, and ethnicity characteristics was selected, until all of the age/sex grids were filled for both ethnic groups. The study was approved by the Research Ethics Committee of King’s College Hospital.
Baseline Assessments
Age, gender, ethnic, and vascular risk profiles were recorded in all of the subjects. Blood pressure, body mass index, abdominal girth, and hip-to-waist ratio were measured using validated techniques. The definition used for the metabolic syndrome was based on epidemiological research and required an alteration in ≥3 of 5 components: waist girth >102 cm for men and >88 cm for women, triglycerides ≥1.7 mmol/L or 150 mg/dL, high-density lipoprotein (HDL) cholesterol <1.1 mmol/L or 40 mg/dL in men and <1.3mmol/L or 50 mg/dL in women, blood pressure >130/85 mm Hg and fasting blood glucose >6.1 mmol/L or 110 mg/dL.16
A blood sample was taken after an overnight fast to assess the biochemical markers of metabolic status (blood glucose, total cholesterol, HDL cholesterol, triglycerides, homocysteine, and insulin) and activation of inflammation [interleukin (IL) 6, tumor necrosis factor (TNF) α, and cytoplasmic repressor protein (CRP)].17 Insulin levels were measured using a DSL-1600 insulin radioimmunoassay (Diagnostics Systems Laboratories). Homocysteine was measured by chemiluminescent immunoassay (Bayer Diagnostics). TNF-α and IL-6 levels were measured using monoclonal ELISA techniques (R&D Systems). CRP was measured using a high-sensitivity turbidimetric immunoassay (WAKO Chemicals) on a Cobas Mira Analyser (Roche Diagnostics). An estimate of insulin sensitivity was derived by homeostasis model assessment (HOMA) using the following formula: fasting plasma glucose (mmols/L) × fasting plasma insulin (μU/mL)/22.5.18 Genotyping for β2 adrenoceptor polymorphisms was undertaken using techniques validated previously19 to adjust for the confounding effect of differences in the distribution of functionally active polymorphisms when assessing ethnic differences in albuterol (ALB)-mediated vasodilation.19,20
Carotid Artery Imaging
Carotid arteries were imaged with high-resolution B mode ultrasound (Accuson Sequoia 512) using an 8-MHz linear transducer. Each examination cycle included sequential longitudinal and transverse views of the common carotid artery, the carotid bifurcation, and the internal carotid artery bulb. Settings for depth-gain compensation, preprocessing, persistence, and postprocessing were held constant. All of the ultrasonic examinations were stored digitally for subsequent offline processing by an experienced ultrasonographer masked to patient identity and ethnicity. Carotid intima media thickness (CIMT) was defined as the mean of differences between the blood/intima borderline and the media/adventitia borderline and was measured over the distal 1 cm of the common carotid artery, just proximal to the bulb on the left and the right side. The mean intracorrelation coefficient for CIMT readings was 0.95 (95% CI, 0.93–0.97).
Measurement of Arterial Function
Small vessel reactivity and large artery stiffness were measured noninvasively using digital volume pulse photoplethysmography (MicroMedical).21,22 All of the assessments were performed in the morning in a temperature-controlled (24±1°C) laboratory with subjects resting supine. The digital volume pulse waveform consists of a systolic (first peak) and a diastolic (second peak) component formed by the reflection of the pulse wave predominantly from small muscular arteries (Figure). The amount of pulse wave reflected depends on the tone of these arteries and can be measured as a percentage of the systolic peak, the reflectance index (RI). Small artery function can be assessed by measuring absolute change in RI from baseline (ΔRI) in response to albuterol (partly mediated by the endothelium) and nitroglycerine (endothelium-independent) at doses that do not change the heart rate or blood pressure.21 The peak-to-peak time (PPT) between the systolic and diastolic peaks is determined by subject height and arterial distensibility. An index of large artery stiffness (SI) can be derived from PPT using the following formula: SI (m/s) = height (m)/PPT (s).22
After resting baseline measurements of heart rate, blood pressure (BP), and RI, subjects were given a predetermined dose of albuterol (5 μg/min) and GTN (5 μg/min) for 30 minutes each separated by a washout period of 60 minutes. Heart rate, BP, and RI were monitored at 3-minute intervals. ΔRI was measured as the mean absolute change in RI from baseline between 12 and 21 minutes for ALB (ΔRIALB) and between 9 and 12 minutes for glyceryl tri nitrate (GTN) (ΔRIGTN). Preliminary studies to test the reliability of methodology in 20 healthy and 20 hypertensive subjects showed that the mean within-subject variation of ΔRI and ΔPPT for repeated measurements was 4.9% and 27.7 ms, respectively, at these time points. Pair-wise comparisons of observations showed that mean intraobserver variability was 4.5±1.1% for ΔRI and 10.1±4.0 ms for PPT.
Statistical Analysis
Mean SD for ΔRI was 11% in preliminary studies, and 77 subjects in each group gave the study 80% power to detect a 5% difference in ΔRI at the 5% (2-sided) significance level. Data are presented as the mean ± SD and were tested for normality using the Kolmogorov-Smirnov test. Most of the data collected showed a normal distribution, with the exception of CRP, IL-6, and TNF-α. These data were logarithmically transformed before analysis. Differences in mean values were compared by the t test for continuous variables and by the χ2 test for categorical variables. The outcome measures of interest were ΔRIALB (endothelium-dependent small artery function), ΔRIGTN (endothelium-independent small artery function), SI (large artery function), and CIMT (arterial morphology). The independent effect of each potential predictor (ethnicity, body mass index, waist-to-hip ratio, blood pressure, fasting glucose, insulin levels, HDL cholesterol levels, and smoking status) was assessed after adjusting for the confounding effects of age, gender, baseline levels of RI, heart rate, and β-adrenoceptor polymorphisms in multiple regression models. Additional models were constructed to investigate the interactions between ethnicity and independent risk factors and the independent contribution of ethnicity to metabolic and inflammatory variables.
Results
The baseline characteristics of the 78 Afro-Caribbeans and 82 Caucasians were comparable for the majority of demographic and metabolic variables (Table 1). Afro-Caribbean subjects had higher mean body mass index (28.6 versus 26.8; P=0.035) and diastolic blood pressure (80.3 versus 77.6 mm Hg; P=0.033) but were comparable for abdominal girth, systolic blood pressure, blood glucose, HDL cholesterol, and triglyceride levels. There were no differences in the prevalence of the clinically defined metabolic syndrome between the groups. The HOMA score was comparable between the 2 groups. The functionally important Gln27 and Arg16 allele polymorphisms were significantly more frequent in Afro-Caribbean subjects.TABLE 1. Baseline Characteristics, β2 Adrenoceptor Polymorphisms, and Vascular Measurements of 78 Afro-Caribbean and 82 Caucasian Subjects
Characteristic | Afro-Caribbean (n=78) | Caucasian (n=82) | P Value |
---|---|---|---|
*Codon 27: χ2 = 31.759, P<0.0001; Codon 16: χ2=31.759, P<0.0001. | |||
Age, years | 53.8 (11.2) | 54.6 (12.4) | 0.66 |
Gender, % female | 51 | 48 | 0.70 |
Current smoker, % | 19 | 18 | 0.85 |
Body mass index, kg/m2 | 28.5 (5.9) | 26.8 (4.3) | 0.03 |
Waist-to-hip ratio | 0.86 (0.06) | 0.87 (0.07) | 0.19 |
Diastolic blood pressure, mm Hg | 80.3 (7.3) | 77.6 (8.4) | 0.03 |
Systolic blood pressure, mm Hg | 131.1 (15.9) | 128.01 (14.2) | 0.19 |
HDL cholesterol, mmol/L | 1.5 (0.4) | 1.6 (0.4) | 0.06 |
Low-density lipoprotein cholesterol, mmol/L | 3.2 (0.7) | 3.2 (0.8) | 0.99 |
Triglycerides, mmol/L | 1.1 (0.7) | 1.3 (0.7) | 0.10 |
Fasting glucose, mmol/L | 5.4 (1.1) | 5.2 (0.8) | 0.12 |
Metabolic syndrome, % | 14 (18) | 15 (18) | 0.98 |
HOMA score | 3.0 (0.9) | 3.2 (1.5) | 0.31 |
β2 polymorphisms | |||
Gln/Gln at Codon 27* | 50/74 (61%) | 23/82 (27%) | <0.0001 |
Arg/Arg at Codon 16* | 17/74 (23%) | 11/82 (13%) | <0.0001 |
Afro-Caribbean subjects had higher fasting insulin levels (14.0 versus 10.6 μU/mL; P=0.026), TNF-α (6.7 versus 4.3 pg/mL; P=0.001), and IL-6 (2.3 versus 1.5 pg/mL; P=0.036) levels (Table 2). The mean CIMT of Afro-Caribbean subjects was greater than that of Caucasian subjects (0.81 versus 0.75 mm; P=0.02; Table 2). Small vessel reactivity of Afro-Caribbean subjects was less than that of Caucasians for ALB (ΔRIALB 6.8 versus 12.3%; P=0.0001) but not for GTN (ΔRIGTN 11.9 versus 13.6%; P=0.06). Mean SI values were comparable between the 2 groups (9.9 versus 9.7 m/s; P=0.48).TABLE 2. Inflammatory and Vascular Markers in 78 Afro-Caribbean and 82 Caucasian Subjects
Characteristics | Afro-Caribbean (n=78) | Caucasian (n=82) | P Value |
---|---|---|---|
Inflammatory markers | |||
Fasting insulin, μU/ml | 14.0 (10.9) | 10.6 (5.7) | 0.03 |
TNF-α, pg/mL | 6.7 (6.1) | 4.3 (3.6) | 0.001 |
IL-6, pg/mL | 2.3 (3.3) | 1.5 (0.7) | 0.04 |
CRP, mg/L | 2.5 (2.9) | 2.1 (2.2) | 0.82 |
Homocysteine, μmol/L | 12.2 (3.0) | 13.3 (6.3) | 0.19 |
Vascular measurements | |||
CIMT, mm | 0.81 (0.20) | 0.75 (0.18) | 0.02 |
Baseline RI, % | 76.2 (8.0) | 74.3 (9.8) | 0.21 |
ΔRIALB, % | 6.8 (8.0) | 12.3 (8.9) | <0.0001 |
ΔRIGTN, % | 11.9 (7.9) | 13.6 (8.1) | 0.058 |
SI, m/s | 9.9 (2.2) | 9.7 (2.4) | 0.48 |
After adjusting for differences in age, hemodynamic parameters, metabolic profile, and frequency of β2 adrenoceptor polymorphisms, CIMT was 0.05 mm greater (95% CI, 0.009–0.09 mm) and ΔRIALB was 2.5% lower (95% CI, 0.2–4.8) in Afro-Caribbean compared with Caucasian subjects (Table 3). TNF-α levels showed an independent relationship with Afro-Caribbean ethnicity (coefficient 0.21; 95% CI, 0.05–0.35; P=0.01) and fasting insulin level (coefficient 0.17; 95% CI, 0.05–1.8; P=0.038). A difference in the SI between the 2 groups was not seen even after adjusting for differences in age and other variables (Table 3). SI increased by 0.3 m/s for every 0.1-mm increase in CIMT (P=0.002), but this effect was seen only in Caucasian and not in Afro-Caribbean subjects (P=0.004).TABLE 3. Multiple Regression Models Evaluating Independent Determinants of Arterial Structure (CIMT), Large Artery Function (SI), and Small Artery Function (ΔRIALB) in the Combined Sample
Characteristic | CIMT (Adjusted R2=0.11) | SI (Adjusted R2=0.23) | ΔRIALB (Adjusted R2=0.66) | ||||||
---|---|---|---|---|---|---|---|---|---|
Coef∥ | 95% CI | P Value | Coef | 95% CI | P Value | Coef¶ | 95% CI | P Value | |
*Regression coefficient describes change for every 5 years in age | |||||||||
†Regression coefficient describes change for every 0.01 unit increase in waist-to-hip ratio. | |||||||||
‡Regression coefficient describes change for every 5mmHg increase in systolic blood pressure. | |||||||||
§Regression coefficient describes change for every 1 mmol increase in fasting blood glucose. | |||||||||
∥Divide coefficients by 100 to interpret as mm change in CIMT. | |||||||||
¶Coefficient adjusted for baseline RI and heart rate. | |||||||||
#CIMT used as an independent variable only for SI and ΔRISLB; significant association only in Caucasians not in Afro-Caribbeans (P<0.004). | |||||||||
Age* | 3.80 | 3.22–4.39 | <0.001 | — | — | — | — | — | — |
Male gender | 0.92 | 0.43–1.41 | <0.001 | −4.70 | −6.98 to −2.43 | <0.001 | |||
Waist-to-hip ratio† | 0.35 | 0.06–0.64 | 0.02 | — | — | — | −0.20 | −0.36 to −0.05 | 0.01 |
Blood pressure‡ | 0.79 | 0.09–1.50 | 0.03 | 0.02 | 0.003–0.03 | 0.02 | −0.42 | −0.64 to −0.19 | <0.001 |
Fasting blood glucose§ | — | — | — | — | — | — | −0.77 | −1.37 to −0.16 | 0.01 |
CIMT# | — | — | — | 0.27 | 0.10–0.43 | 0.002 | — | — | — |
Current smoker | 4.06 | 0.13–7.98 | 0.04 | 0.75 | 0.11–1.39 | 0.02 | −4.83 | −6.88 to −2.77 | <0.001 |
Afro-Caribbean vs Caucasian | 5.14 | 0.87–9.42 | 0.02 | −0.01 | −0.72 to 0.69 | 0.97 | −2.50 | −4.81 to −0.19 | 0.03 |
In addition to Afro-Caribbean ethnicity, increasing age, waist-to-hip ratio, higher blood pressure, and smoking were independently associated with greater CIMT (Table 3). Male gender, waist-to-hip ratio, increasing blood pressure, and smoking were other independent determinants of ΔRIALB. β2-Adrenoceptor polymorphisms at codon 27 (β=0.03; P=0.79) or codon 16 (β=0.004; P=0.97) did not have an independent effect on ΔRIALB. There were no significant interactions between ethnicity and age, gender, blood pressure, obesity, and smoking for increases in CIMT or attenuation of ΔRIALB. Arterial stiffness was greater in men and smokers and increased with blood pressure (Table 3). There was a significant interaction between Caucasian ethnicity and CIMT for large artery stiffness.
Discussion
Afro-Caribbean subjects without clinical features of vascular disease had greater carotid intima media thickness, attenuated endothelium-mediated small vessel reactivity, higher insulin levels, and increased inflammatory markers compared with matched Caucasians. Large vessel stiffness of Afro-Caribbeans was comparable with Caucasians despite greater CIMT, and there was an independent association between artery intima thickness and large artery stiffness in Caucasians but not in Afro-Caribbeans. This suggests that Afro-Caribbean subjects have selective impairment of small artery, but not large artery, function associated with inflammatory activation, which may be responsible for the higher prevalence of small vessel disease in Afro-Caribbean subjects. These findings are consistent with studies showing few atherosclerotic changes in the large arteries of patients with small vessel disease23 and hyperinsulinaemia in black, but not white, hypertensive subjects with end organ damage.15
Increased carotid intima media thickness24 and attenuated vascular reactivity10,14 but better large vessel function25–28 have been described in Afro-Caribbeans previously, but this is the first study in which all of these aspects have been examined together in community settings. Explanations for population differences in disease susceptibility must be sought in representative samples of the general population to ensure unbiased and generalizable comparisons.25 The family practice register is the most accurate and comprehensive register of the general population in the United Kingdom and was used to obtain a representative sample of the each ethnic group. The difficulties in measuring vascular function in large community-based studies are well known;29 this study used noninvasive techniques, which were simple, free of operator error, and validated previously against widely accepted but logistically difficult methods.21,22,29–31 In addition, experimental design, measurement techniques, and reproducibility of vascular measurements were established in pilot experiments before the study.
Recent literature suggests that arterial walls show different functional and morphological responses to hemodynamic or inflammatory challenges under different conditions32–34 and may provide possible explanations for ethnic differences observed in this study. It is likely that increased CIMT in Afro-Caribbean subjects reflects vascular remodeling to accommodate increased circumferential and shear stress on the vessel wall because of higher blood pressures rather than large vessel atherosclerosis.34,35 TNF-α and IL-6 are known to block the action of insulin and induce vascular inflammation,36 and hyperinsulinaemia has been observed in patients with small vessel cerebrovascular disease13 and in black hypertensives with end organ damage.15 These observations tie in with the findings in our study and suggest the possibility of a clinically significant link among early metabolic disturbances, activation of inflammation, and small vessel pathology in Afro-Caribbean people.
An interesting finding was that HOMA-IR scores of Afro-Caribbeans were comparable with Caucasians despite significantly higher insulin levels. Although this may represent very early stages in the development of insulin resistance, it is more likely that HOMA methods are relatively insensitive, and glucose clamp studies may have produced different results.37 Another unexpected observation was the lack of difference in CRP levels despite elevated IL-6 and TNF-α levels in Afro-Caribbeans. The relationship among IL-6, raised CRP, and atherosclerosis is well established, but associations between CRP and small vessel disease remain unclear.38 There is also a possibility that ethnic differences in CRP levels may have confounded CRP comparisons in this study.39
A limitation of this study is its cross-sectional design; a longitudinal design would be required to assess the progression of vascular and inflammatory changes and establish their relationship to clinical end points. However, only a few subjects in any healthy cohort will experience stroke or other vascular diseases, and it may not be feasible to undertake measurements with the same rigor in a large number of subjects over time. Inclusion of subjects with vascular risk factors may have magnified the differences between small and large vessel function but would have confounded the effects of ethnicity. Although previous studies have demonstrated the predominance of small arteries and endothelium mechanisms in pulse wave responses measured by digital plethysmography,21,22,29,30 it is possible that wave reflection may also have occurred from sites other than small arteries, and activation of cAMP pathways in the vascular smooth muscle may have contributed to vasodilation with ALB. Any bias because of these limitations would apply equally to both ethnic groups and does not affect the interpretation of findings. Because there is no reliable method for assessing cerebral vascular beds, findings in the peripheral circulation have been extrapolated to cerebral vascular beds. Such extrapolation is supported by evidence that peripheral vascular measurements are a reliable indicator of more widespread changes in both arterial structure and function.40
This study suggests that differences in vessel wall response of different arteries to hemodynamic and inflammatory challenges may contribute to different manifestations of vascular disease in different ethnic groups, which may prove important in responsiveness to preventive or therapeutic interventions. The study also confirms the importance of conventional risk factors, such as age, gender, and high blood pressure in the etiology of vascular disease, which still remain the main targets for detection and prevention of vascular disease in both ethnic groups. Although additional research is needed to define mechanisms underlying ethnic differences in vascular response and develop specific interventions, effective implementation of proven measures, such as blood pressure reduction, cessation of smoking, and rectification of metabolic abnormalities, remains the cornerstone for reducing racial disparity and excess burden of vascular disease in people of African descent.
Footnotes
At the time of the study, P.C. was a director and shareholder in Micro Medical Ltd. These interests are no longer held (as of March 2005), but ongoing research support is received from Micro Medical (now part of Viasys Health Care Inc).
L.K. and C.R. contributed equally to this work.
References
1.
Corbin DO, Poddar V, Hennis A, Gaskin A, Rambarat C, Wilks R, Wolfe CD, Fraser HS. Incidence and case fatality rates of first-ever stroke in a black Caribbean population: the Barbados Register of Strokes. Stroke. 2004; 35: 1254–1258.
2.
Schneider AT, Kissela B, Woo D, Kleindorfer D, Alwell K, Miller R, Szaflarski J, Gebel J, Khoury J, Shukla R, Moomaw C, Pancioli A, Jauch E, Broderick J. Ischemic stroke subtypes: a population-based study of incidence rates among blacks and whites. Stroke. 2004; 35: 1552–1556.
3.
Lopes AA. Relationships of race and ethnicity to progression of kidney dysfunction and clinical outcomes in patients with chronic kidney failure. Adv Ren Replace Ther. 2004; 11: 14–23.
4.
Li S, McAlpine DD, Liu J, Li S, Collins AJ. Differences between blacks and whites in the incidence of end-stage renal disease and associated risk factors. Adv Ren Replace Ther. 2004; 11: 5–13.
5.
Kittner S, White L, Losonczy K, Wolf P, Hebel R. Black-White differences in stroke incidence in a national sample: The contribution of hypertension and diabetes mellitus. JAMA. 1990; 264: 1267–1270.
6.
Otten M, Teutsch S, Williamson D, Marks J. The effect of known risk factors on the excess mortality of Black adults in the United States. J Am Med Assoc. 1990; 263: 845–850.
7.
McGruder HF, Malarcher AM, Antoine TL, Greenlund KJ, Croft JB. Racial and ethnic disparities in cardiovascular risk factors among stroke survivors. United States 1999 to 2001. Stroke. 2004; 35: 1557–1561.
8.
Hall WD, Clark LT, Wenger NK, Wright JT Jr., Kumanyika SK, Watson K, Horton EW, Flack JM, Ferdinand KC, Gavin JR 3rd, Reed JW, Saunders E, O’Neal W Jr. African-Am Lipid and Cardiovascular Council. The Metabolic Syndrome in African Americans: a review. Ethn Dis. 2003; 13: 414–428.
9.
Lang CC, Stein CM, Brown RM, Deegan R, Nelson R, He HB, Wood M, Wood AJ. Attenuation of isoproterenol-mediated vasodilatation in blacks. N Engl J Med. 1995; 333: 155–160.
10.
Kelsey RM, Alpert BS, Patterson SM, Barnard M. Racial differences in hemodynamic responses to environmental thermal stress among adolescents. Circulation. 2000; 101: 2284–2289.
11.
Targonski PV, Bonetti PO, Pumper GM, Higano ST, Holmes DR Jr., Lerman A. Coronary endothelial dysfunction is associated with an increased risk of cerebrovascular events. Circulation. 2003; 107: 2805–1809.
12.
Hassan A, Hunt BJ, O’Sullivan M, Parmar K, Bamford JM, Briley D, Brown MM, Thomas DJ, Markus HS. Markers of endothelial dysfunction in lacunar infarction and ischaemic leukoaraiosis. Brain. 2003; 126: 424–432.
13.
Kario K, Matsuo T, Kobayashi H, Hoshide S, Shimada K. Hyperinsulinemia and hemostatic abnormalities are associated with silent lacunar cerebral infarcts in elderly hypertensive subjects. J Am Coll Cardiol. 2001; 37: 871–877.
14.
Kahn DF, Duffy SJ, Tomasian D, Holbrook M, Rescorl L, Russell J, Gokce N, Loscalzo J, Vita JA. Effects of black race on forearm resistance vessel function. Hypertension. 2002; 40: 195–201.
15.
El-Gharbawy AH, Kotchen JM, Grim CE, Kaldunski M, Hoffmann RG, Pausova Z, Gaudet D, Gossard F, Hamet P, Kotchen TA. Predictors of target organ damage in hypertensive blacks and whites. Hypertension. 2001; 38: 761–766.
16.
National Institutes of Health. Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Bethesda, MD: National Institutes of Health; 2001; NIH Publication 01–3670.
17.
Festa A, Agostino RD Jr., Howard G, Mykkanen L, Tracy RP, Haffner SM. Chronic subclinical inflammation as part of the insulin resistance syndrome. The Insulin Resistance Atherosclerosis Study. Circulation. 2000; 102: 42–47.
18.
Matthews D, Hosker J, Rudenski A, Naylor B, Treacher D, Turner R. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985; 28: 412–419.
19.
Cockcroft JR, Gazis AG, Cross DJ, Wheatley A, Dewar J, Hall IP, Noon JP. Beta(2)-adrenoceptor polymorphism determines vascular reactivity in humans. Hypertension. 2000; 36: 371–375.
20.
Wood AJ. Variability in beta-adrenergic receptor response in the vasculature: Role of receptor polymorphism. J Allergy Clin Immunol. 2002; 110 (6 Suppl): S318–S21.
21.
Chowienczyk PJ, Kelly R, MacCallum H, Millasseau SC, Andersson T, Gosling RG, Ritter JM, Anggard EE. Photoplethysmographic assessment of pulse wave reflection: blunted response to endothelium dependent beta2 adrenergic vasodilation in Type II diabetes mellitus. J Am Coll Cardiol. 1999; 34: 2007–2014.
22.
Millasseau SC, Kelly RP, Ritter JM, Chowienczyk PJ. Determination of age-related increases in large artery stiffness by digital pulse contour analysis. Clin Sci (Lond). 2002; 103: 371–377.
23.
Arboix A, Marti-Vilalta JL. New concepts in lacunar stroke aetiology: the constellation of small-vessel arterial disease. Cerebrovasc Dis. 2004; 17 (Suppl 1): 58–62.
24.
D’Agostino RB Jr., Burke G, O’Leary D, Rewers M, Selby J, Savage PJ, Saad MF, Bergman RN, Howard G, Wagenknecht L, Haffner SM. Ethnic differences in carotid wall thickness. The Insulin Resistance Atherosclerosis Study. Stroke. 1996; 27: 1744–1749.
25.
Chaturvedi N, Bulpitt CJ, Leggetter S, Schiff R, Nihoyannopoulos P, Strain WD, Shore AC, Rajkumar C. Ethnic differences in vascular stiffness and relations to hypertensive target organ damage. J Hypertens. 2004; 22: 1731–1737.
26.
Rajkumar C, Mensah R, Meeran K, Armstrong S, Bulpitt CJ. Peripheral arterial compliance is lower in Afro-Caribbeans compared to white Caucasians with type 2 diabetes after adjustment for blood pressure. J Hum Hypertens. 1999; 13: 841–843.
27.
Mackey RH, Sutton-Tyrrell K, Vaitkevicius PV, Sakkinen PA, Lyles MF, Spurgeon HA, Lakatta EG, Kuller LH. Correlates of aortic stiffness in elderly individuals: a subgroup of the Cardiovascular Health Study. Am J Hypertens. 2002; 15: 16–23.
28.
Weinberger MH, Fineberg NS, Fineberg SE. Effects of age, race, gender, blood pressure, and estrogen on arterial compliance. Am J Hypertens. 2002; 15: 358–363.
29.
Wilkinson IB, Hall IR, MacCallum H, Mackenzie IS, McEniery CM, van der Arend BJ, Shu YE, MacKay LS, Webb DJ, Cockcroft JR. Pulse-wave analysis: clinical evaluation of a noninvasive, widely applicable method for assessing endothelial function. Arterioscler Thromb Vasc Biol. 2002; 22: 147–152.
30.
Bortolotto LA, Blacher J, Kondo T, Takazawa K, Safar ME. Assessment of vascular aging and atherosclerosis in hypertensive subjects: second derivative of photoplethysmogram versus pulse wave velocity. Am J Hypertens. 2000; 13: 165–171.
31.
Oliver JJ, Webb DJ. Noninvasive assessment of arterial stiffness and risk of atherosclerotic events. Arterioscler Thromb Vasc Biol. 2003; 23: 554–566.
32.
Mourad J-J, Girerd X, Boutouyrie P, Safar M, Laurent S. Opposite effects of remodeling and hypertrophy on arterial compliance in hypertension. Hypertension. 1998; 31: 529–533.
33.
van der Heijden-Spek JJ, Staessen JA, Fagard RH, Hoeks AP, Struijker Boudier HA, van Bortel LM. Effect of age on brachial artery wall properties differs from the aorta and is gender dependent. Hypertension. 2000; 35: 637–642.
34.
Gibbons GH, Dzau VJ. The emerging concept of vascular remodeling. N Engl J Med. 1994; 330: 1431–1438.
35.
Mulvany MJ, Baumbach GL, Aalkjaer C, Heagerty AM, Korsgaard N, Schiffrin EL, Heistad DD. Vascular remodeling. Hypertension. 1996; 28: 505–506.
36.
Fernandez-Real JM, Ricart W. Insulin resistance and chronic cardiovascular inflammatory syndrome. Endocrine Reviews. 2003; 24: 278–301.
37.
Wallace TM, Matthews DR. The assessment of insulin resistance in man. Diabet Med. 2002; 19: 527–534.
38.
Yudkin JS, Kumari M, Humphries SE, Mohamed-Ali V. Inflammation, obesity, stress and coronary heart disease: is interleukin-6 the link? Atherosclerosis. 2000; 148: 209–214.
39.
Anand SS, Razak F, Yi Q, Davis B, Jacobs R, Vuksan V, Lonn E, Teo K, McQueen M, Yusuf S. C-reactive protein as a screening test for cardiovascular risk in a multiethnic population. Arterioscler Thromb Vasc Biol. 2004; 24: 1509–1515.
40.
Kuvin JT, Karas RH. Clinical utility of endothelial function testing: ready for prime time? Circulation. 2003; 107: 3243–3247.
Information & Authors
Information
Published In
Copyright
© 2005.
Versions
You are viewing the most recent version of this article.
History
Received: 31 May 2005
Accepted: 24 July 2005
Published online: 25 August 2005
Published in print: 1 November 2005
Keywords
Authors
Metrics & Citations
Metrics
Citations
Download Citations
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Select your manager software from the list below and click Download.
- Aortic Distensibility Measured by Automated Analysis of Magnetic Resonance Imaging Predicts Adverse Cardiovascular Events in UK Biobank, Journal of the American Heart Association, 11, 23, (2022)./doi/10.1161/JAHA.122.026361
- Cardiovascular Disease Risk Factor Burden During the Menopause Transition and Late Midlife Subclinical Vascular Disease: Does Race/Ethnicity Matter?, Journal of the American Heart Association, 9, 4, (2020)./doi/10.1161/JAHA.119.013876
- Distinct inflammatory mediator patterns in young black and white adults: The African-predict study, Cytokine, 126, (154894), (2020).https://doi.org/10.1016/j.cyto.2019.154894
- Tempol augments the blunted cutaneous microvascular thermal reactivity in healthy young African Americans, Experimental Physiology, 103, 3, (343-349), (2018).https://doi.org/10.1113/EP086776
- Aerobic Exercise Training and Arterial Changes in African Americans versus Caucasians, Medicine & Science in Sports & Exercise, 48, 1, (90-97), (2016).https://doi.org/10.1249/MSS.0000000000000742
- Exercise Interventions and Peripheral Arterial Function: Implications for Cardio-Metabolic Disease, Progress in Cardiovascular Diseases, 57, 5, (521-534), (2015).https://doi.org/10.1016/j.pcad.2014.12.005
- Defining the System: Contributors to Exercise Limitations in Heart Failure, Heart Failure Clinics, 11, 1, (1-16), (2015).https://doi.org/10.1016/j.hfc.2014.08.009
- Can common carotid intima media thickness serve as an indicator of both cardiovascular phenotype and risk among black Africans?, European Journal of Preventive Cardiology, 22, 11, (1442-1451), (2014).https://doi.org/10.1177/2047487314547656
- Ethnic differences in microvascular function in apparently healthy South African men and women, Experimental Physiology, 99, 7, (985-994), (2014).https://doi.org/10.1113/expphysiol.2014.078519
- Inflammation and Hypertension: Are There Regional Differences?, International Journal of Hypertension, 2013, (1-12), (2013).https://doi.org/10.1155/2013/492094
- See more
Loading...
View Options
Login options
Check if you have access through your login credentials or your institution to get full access on this article.
Personal login Institutional LoginPurchase Options
Purchase this article to access the full text.
eLetters(0)
eLetters should relate to an article recently published in the journal and are not a forum for providing unpublished data. Comments are reviewed for appropriate use of tone and language. Comments are not peer-reviewed. Acceptable comments are posted to the journal website only. Comments are not published in an issue and are not indexed in PubMed. Comments should be no longer than 500 words and will only be posted online. References are limited to 10. Authors of the article cited in the comment will be invited to reply, as appropriate.
Comments and feedback on AHA/ASA Scientific Statements and Guidelines should be directed to the AHA/ASA Manuscript Oversight Committee via its Correspondence page.