Should obesity be blamed for the high prevalence rates of hypertension in black South African women?

Is BMI a Useful Indicator of Prenatal Health Among Black American Women?

OBJECTIVE

BMI is commonly used to measure risk to prenatal health but may not be sensitive to adiposity-associated health problems for Black women. The aim of the present study was to test associations between indices of prenatal health and BMI in Black women.

METHODS

Data were from 652 women enrolled in two studies. Height and weight were used to calculate BMI. Depression and perceived stress were measured via maternal report, systemic inflammation via C-reactive protein (CRP), and nutrition by the ratio of omega-3 docosahexaenoic acid to omega-6 arachidonic acid fatty acids.

RESULTS

Neither perceived stress, depression, nor fatty acids were associated with prenatal BMI. CRP levels were positively associated with BMI (beta = 6.56, t = 13.30, p < .001). The prevalence of high-risk levels of CRP (> 3 mg/L) was below 10% for all weight classes except for BMI ≥ 40.

CONCLUSIONS

Results suggest that BMI may not be a sensitive index of adiposity related risk to prenatal health for Black women.

Inflammation and hypertension development: A longitudinal analysis of the African-PREDICT study

Background

The role of inflammation in the development of hypertension remains incompletely understood. While single inflammatory mediators have been shown to associate with changes in blood pressure (ΔBP), the role of clusters of inflammatory mediators has been less comprehensively explored. We therefore determined whether individual or clusters of inflammatory mediators from a large biomarker panel were associated with ΔBP over 4.5 years, in young healthy adults.

Methods

We included 358 adults (white, n = 156; black, n = 202) with detailed information on ambulatory blood pressure (BP) at baseline and follow-up. Baseline blood samples were analysed for 22 inflammatory mediators using multiplexing technology. Principal component analysis was used to study associations between clusters of inflammatory mediators and ΔBP.

Results

In the total cohort in multivariable-adjusted regression analyses, percentage change in 24hr systolic BP associated positively with Factors 1 (Interferon-gamma, interleukin (IL)-4, IL-7, IL-10, IL-12, IL-17A, IL-21, IL-23, macrophage inflammatory protein (MIP)-1α, MIP-1β, TNF-α, granulocyte-macrophage colony-stimulating factor (GM-CSF)) and 2 (IL-5, IL-6, IL-8, IL-13). Change in daytime systolic BP associated positively with Factors 1, 2 and 3 (C-Reactive protein, IL-1β, IL-2, MIP-3α). Subgroup analysis found these findings were limited to white study participants. Numerous associations were present between individual inflammatory mediators (Interferon-gamma, GM-CSF, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17A, IL-21, IL-23, MIP-1α and MIP-1β) and ΔBP in the white but not black subgroups.

Conclusion

We found independent relationships between numerous inflammatory mediators (individual and clusters) and ΔBP over 4.5 years. The relationship between inflammatory markers and ΔBP was only found in white participants. ClinicalTrials.gov (Identifier: NCT03292094)..

Genetics of Circulating Resistin Level, a Biomarker for Cardiovascular Diseases, Is Informed by Mendelian Randomization and the Unique Characteristics of African Genomes

BACKGROUND

Resistin, a protein linked with inflammation and cardiometabolic diseases, is one of few proteins for which genome-wide association studies consistently report variants within and near the coding gene (RETN). Here, we took advantage of the reduced linkage disequilibrium in African populations to infer genetic causality for circulating resistin levels by performing genome-wide association studies, whole-exome analysis, fine mapping, Mendelian randomization, and transcriptomic data analyses.

METHODS

Genome-wide association studies and fine-mapping analyses for resistin were performed in 5621 African-ancestry individuals, including 3754 continental Africans and 1867 African Americans. Causal variants identified were subsequently used as an instrumental variable in Mendelian randomization analyses for homeostatic modeling-derived insulin resistance index, body mass index, and type 2 diabetes.

RESULTS

The lead variant (rs3219175, in the promoter region of RETN) for the single locus detected was the same for continental Africans (P=5.0×10^-111) and for African Americans (9.5×10^-38), respectively explaining 12.1% and 8.5% of variance in circulating resistin. Fine-mapping analyses and functional annotation revealed this variant as likely causal affecting circulating resistin levels as a cis-eQTL increasing RETN expression. Additional variants regulating resistin levels were upstream of RETN with genes PCP2, STXBP2, and XAB2 showing the strongest association using integrative analysis of genome-wide association studies with transcriptomic data. Mendelian randomization analyses did not provide evidence for resistin increasing insulin resistance, body mass index, or type 2 diabetes risk in African-ancestry populations.

CONCLUSIONS

Taking advantage of the fine-mapping resolution power of African genomes, we identified a single variant (rs3219175) as the likely causal variant responsible for most of the variability in circulating resistin levels. In contrast to findings in some other ancestry populations, we showed that resistin does not seem to increase insulin resistance and related cardiometabolic traits in African-ancestry populations.

Plasminogen activator inhibitor-1 activity and the 4G/5G polymorphism are prospectively associated with blood pressure and hypertension status

OBJECTIVES

Plasminogen activator inhibitor-1 (PAI-1) has consistently shown positive associations with blood pressure (BP). Whether elevations in PAI-1 levels precede or result from raised BP is still under debate and data on prospective studies are limited. Hence, we investigated the prospective associations of PAI-1 and the 4G/5G polymorphism with brachial and central BP and pulse pressure (PP) over a 10-year period.

METHODS

Black South Africans aged 30 years and older were included. Baseline data collection commenced in 2005 (n = 2010) with follow-up data collection in 2010 (n = 1288) and 2015 (n = 926). Plasma PAI-1 activity (PAI-1act), 4G/5G polymorphism genotyping, waist circumference and BP measurements were performed and analysed using sequential regression and mixed models.

RESULTS

In multivariable adjusted analyses, PAI-1act and the 4G/4G (vs. the 5G/5G) genotype increased the odds of developing hypertension in the total group [1.04 (1.01; 1.08) and 1.82 (1.07; 3.12) respectively]. Furthermore, PAI-1act was prospectively associated with brachial SBP (r = 0.0815) and PP (r = 0.0832) in the total group, and with central PP in women (r = 0.1125; all P < 0.05). Addition of waist circumference to the models either decreased or nullified the contribution of PAI-1act to BP and hypertension development.

CONCLUSION

PAI-1act and the 4G/4G (vs. the 5G/5G) genotype increased the odds of developing hypertension. Furthermore, PAI-1act associated prospectively with both brachial and central BP. These associations were mediated in part by central adiposity. The study supports the hypothesis that PAI-1 also contributes to hypertension development rather than solely being a consequence thereof.

Recent advances in understanding hypertension development in sub-Saharan Africa

Consistent reports indicate that hypertension is a particularly common finding in black populations. Hypertension occurs at younger ages and is often more severe in terms of blood pressure levels and organ damage than in whites, resulting in a higher incidence of cardiovascular disease and mortality. This review provides an outline of recent advances in the pathophysiological understanding of blood pressure elevation and the consequences thereof in black populations in Africa. This is set against the backdrop of populations undergoing demanding and rapid demographic transition, where infection with the human immunodeficiency virus predominates, and where under and over-nutrition coexist. Collectively, recent findings from Africa illustrate an increased lifetime risk to hypertension from foetal life onwards. From young ages black populations display early endothelial dysfunction, increased vascular tone and reactivity, microvascular structural adaptions as well as increased aortic stiffness resulting in elevated central and brachial blood pressures during the day and night, when compared to whites. Together with knowledge on the contributions of sympathetic activation and abnormal renal sodium handling, these pathophysiological adaptations result in subclinical and clinical organ damage at younger ages. This overall enhanced understanding on the determinants of blood pressure elevation in blacks encourages (a) novel approaches to assess and manage hypertension in Africa better, (b) further scientific discovery to develop more effective prevention and treatment strategies and

Cardiac Troponin T as Early Marker of Subclinical Cardiovascular Deterioration in Black Hypertensive Women

BACKGROUND

Hypertensive heart disease is a rising concern, especially among black South African women. As high sensitivity cardiac troponin T (cTnT) is a marker of cardiomyocyte damage, we determined the potential link of (i) systemic endothelial dysfunction (reflected by urinary albumin-to-creatinine ratio), (ii) large artery stiffness, (iii) cardiac volume load (estimated by the N-terminal prohormone B-type natriuretic peptide (Nt-proBNP)), and (iv) ECG left ventricular hypertrophy in post-menopausal black women.

METHODS

In 121 (50 normotensive and 71 hypertensive) black women (mean age: 60.6 years), basic cardiovascular assessments including blood pressure and ECG were performed, along with plasma and urinary biomarkers including cTnT.

RESULTS

The cTnT levels (p=0.049) along with Nt-proBNP (p=0.003), pulse pressure (p<0.0001) and the Cornell product (p=0.030) were higher in hypertensive than normotensive women. Only in hypertensive women, was cTnT independently associated with urinary albumin-to-creatinine ratio (β=0.25; p=0.019), pulse pressure (β=0.31; p=0.019), Nt-proBNP (β=0.47; p<0.0001) and Cornell product (β=0.31; p=0.018). An independent association between albumin-to-creatinine ratio and cTnT was also evident in normotensive women (β=0.34; p=0.037).

CONCLUSION

We found cTnT to be a useful marker in an elderly black population relating to several measures of cardiovascular deterioration - from subclinical endothelial dysfunction to left ventricular hypertrophy.

The Role of Body Fat and Fat Distribution in Hypertension Risk in Urban Black South African Women

Developing countries are disproportionately affected by hypertension, with Black women being at greater risk, possibly due to differences in body fat distribution. The objectives of this study were: (1) To examine how different measures of body composition are associated with blood pressure (BP) and incident hypertension; (2) to determine the association between baseline or change in body composition, and hypertension; and (3) to determine which body composition measure best predicts hypertension in Black South African women. The sample comprised 478 non-hypertensive women, aged 29–53 years. Body fat and BP were assessed at baseline and 8.3 years later. Body composition was assessed using dual-energy X-ray absorptiometry (DXA) (n = 273) and anthropometry. Hypertension was diagnosed based on a systolic/diastolic BP ≥140/90 mmHg, or medication use at follow-up. All body composition measures increased (p<0.0001) between baseline and follow-up. SBP and DBP increased by ≥20%, resulting in a 57.1% cumulative incidence of hypertension. Both DXA- and anthropometric-derived measures of body composition were significantly associated with BP, explaining 3–5% of the variance. Baseline BP was the most important predictor of hypertension (adjusted OR: 98–123%). Measures of central adiposity were associated with greater odds (50–65%) of hypertension than total adiposity (44–45%). Only change in anthropometric-derived central fat mass predicted hypertension (adjusted OR: 32–40%). This study highlights that body composition is not a major determinant of hypertension in the sample of black African women. DXA measures of body composition do not add to hypertension prediction beyond anthropometry, which is especially relevant for African populations globally, taking into account the severely resource limited setting found in these communities.

A comparison of the cardiometabolic profile of black South Africans with suspected non-alcoholic fatty liver disease (NAFLD) and excessive alcohol use

Excessive alcohol use and non-alcoholic fatty liver disease (NAFLD) are putative cardiovascular disease risk factors. In order to ease the identification of these conditions on primary health care level, we aimed to determine and compare the demographic and cardiometabolic characteristics of excessive alcohol users and those with suspected NAFLD in black South Africans. In the Prospective Urban Rural Epidemiology study (North West Province, South Africa, N = 2021, collected in 2005) we selected 338 participants, namely: 1) alcohol users (N = 143) reporting 'yes' to alcohol intake, with high gamma-glutamyl transferase (GGT) ≥80 U/L and a percentage carbohydrate deficient transferrin (%CDT) ≥2%; 2) non-alcohol users (N = 127) self-reporting 'no' to alcohol intake with GGT ≤30 U/L and %CDT ≤2%; and 3) NAFLD group (N = 68) who were non-drinkers with GGT levels ≥60 U/L and %CDT ≤ 2%. The demographics indicated that the alcohol users were mostly men (73%) with a body mass index (BMI) of 19.8 (15.2-27.3) kg/m(2), 90% of which were smokers. Systolic blood pressure (SBP) of alcohol users significantly correlated with high-density lipoprotein cholesterol (HDL-C) (β = 0.24; p = 0.003) and waist circumference (WC) (β = 0.22; p = 0.006). Non-alcohol users were mostly women (84%) with a BMI of 26.0 (18.0-39.2) kg/m(2) and blood pressure in this group related positively with triglycerides. The NAFLD group were also mostly women (72%) with a comparatively larger WC (p < 0.001) and an adverse metabolic profile (total cholesterol: 5.55 ± 1.69 mmol/L; glycosylated hemoglobin: 6.03 (4.70-9.40) %). Diastolic blood pressure in the NAFLD group associated positively with WC (β = 0.27; p = 0.018). We therefore found disparate gender and cardiometabolic profiles of black South Africans with suspected NAFLD and excessive alcohol use. The described profiles may aid health care practitioners in low resource settings when using these crude screening measures of gender, obesity indices (and self-reported alcohol use) to identify individuals at risk.

Metabolically healthy obesity from childhood to adulthood - Does weight status alone matter?

Up to 30% of obese people do not display the "typical" metabolic obesity-associated complications. For this group of patients, the term "metabolically healthy obese (MHO)" has been established during the past years and has been the focus of research activities. The development and severity of insulin resistance as well as (subclinical) inflammations seems to play a key role in distinguishing metabolically healthy from metabolically non-healthy individuals. However, an internationally consistent and accepted classification that might also include inflammatory markers as well as features of non-alcoholic fatty liver disease is missing to date, and available data - in terms of prevalence, definition and severity - are heterogeneous, both during childhood/adolescence and during adulthood. In addition, the impact of MHO on future morbidity and mortality compared to obese, metabolically non-healthy as well as normal weight, metabolically healthy individuals is absolutely not clear to date and even conflicting. This review summarizes salient literature related to that topic and provides insight into our current understanding of MHO, covering all age spans from childhood to adulthood.

Body adiposity indices are associated with hypertension in a black, urban Free State community

BACKGROUND

Non-communicable diseases, including hypertension, are increasing rapidly in resource-poor, developing countries amongst populations transitioning from traditional to westernised lifestyles; and are associated with excess weight.

AIM

To investigate the relationship between hypertension and various indices of body adiposity in a transitioning, urban, black population.

SETTING

Three hundred and thirty-nine adults (25-64 years) from a larger cross-sectional study (Assuring Health for All in the Free State) conducted in Mangaung, South Africa, were included.

METHODS

Standard techniques were used to determine blood pressure, HIV status, body mass index (BMI), waist-to-height ratio (WHtR) and body adiposity index (BAI).

RESULTS

Approximately 40% of the sample was HIV-positive and 63.4% hypertensive, with the greatest risk of hypertension being amongst older men. Based on BMI, 23.0% were overweight and 32.1% obese. Waist-to-height ratio showed that 58.6% had increased cardiovascular risk. Mean BAI was 34.1%, whilst 76.3% had a body fat percentage in the overweight/obese category. Waist circumference representing increased cardiovascular risk was found in 44.3% of women and 3.9% of men. Significant positive correlations between mean arterial bloodpressure and BMI (r = 0.261; p < 0.001), WHtR (r = 0.357; p < 0.001) and BAI (r = 0.245; p <0.001) were found. WHtR was a stronger predictor of mean arterial pressure than BMI or BAI. HIV status showed an inverse correlation with all adiposity indices (p < 0.001).

CONCLUSION

Our findings promote WHtR as a practical screening tool for increased hypertension risk in populations undergoing westernisation, and support weight loss as afirst-line intervention for the prevention and management of hypertension.

The nutrition situation of free-living elderly in Umlazi township, South Africa

The risk for non-communicable diseases such as hypertension, diabetes, stroke and ischaemic heart disease in the elderly continues to be on the increase. It is shaped and modified by factors such as economic status and experiences across the whole lifespan. Although malnutrition in this population could be due to poor dietary practices, the nutrition transition of communities in South Africa is partially responsible for nutritional problems. Because of the degree of dependency on others for help and care in communities, the elderly are at risk for malnutrition. The elderly of the Umlazi community are overburdened with the social responsibility of grandchildren and trying to bring stability by managing various households. This becomes a double burden and puts more strain on their quality of life, further impacting on their nutritional status.Die risiko vir chroniese siektes soos hipertensie, diabetes, beroerte en hartkwaal is steeds baie hoog in die bejaardes in Suid Afrika. Dit word deur faktore soos ekonomiese status en ervarings oor die hele lewesiklus gevorm en verander. Voedings probleme wat geïndentifiseer is in die studie hou verband met dieettekorte, alhoewel probleme met oorvoeding verband kan hou met die voedings oorgang wat plaasvind in Suid Afrikaanse gemeenskappe. In verskeie gemeenskappe, as gevolg van die graad van afhanklikheid van ander vir hulp en sorg, is die bejaardes blootgestel aan die risiko van wanvoeding. Die bejaardes van die Umlazi gemeenskap is oorlaai met die sosiale verantwoordelikheid van kleinkinders en probeer om verskeie huishoudings te stabiliseer, wat ‘n dubbele las op hulle plaas en dit kan hulle lewenskwaliteit affekteer wat dan hul voedingstatus verder kan vererger.

Obesity and its health impact in Africa: a systematic review

Abstract

Obesity and its association with co-morbidities in Africa are on the rise. This systematic review examines evidence of obesity and its association with co-morbidities within the African continent. Comparative studies conducted in Africa on adults 17 years and older with mean body mass index (BMI) ≥ 28 kg/m² were included. Five electronic databases were searched. Surveys, case–control and cohort studies from January 2000 to July 2010 were evaluated. Of 720 potentially relevant articles, 10 met the inclusion criteria. Prevalence of obesity was higher in urban than rural subjects with significant increases in obesity rates among women. Inflammatory marker levels were significantly elevated among Africans compared with Caucasians. The co-relationship between obesity and chronic diseases was also highlighted. This systematic review demonstrates that while obesity remains an area of significant public health importance to Africans, particularly in urban areas, there is little evidence of proper diagnosis, treatment and/or prevention.

Exploring the link between cardiovascular reactivity and end-organ damage in African and Caucasian men: the SABPA study

BACKGROUND

Heart failure in the African population is reaching alarming levels. Increased afterload as a result of increased vasoconstriction during stress may lead to impaired ventricular function and stroke volume (SV) as well as vascular hypertrophy. In this study, we challenged the cardiovascular system in order to evaluate the possible contribution of indicators of α-adrenergic vasoconstriction (i.e., vascular resistance and SV reactivity) on left ventricular mass and carotid intima-media thickness (CIMT) in African and Caucasian men.

METHODS

We evaluated 101 African and 101 Caucasian male schoolteachers. Ambulatory blood pressure measurements were taken. Total peripheral resistance, Windkessel compliance and SV, and resting and reactivity values were obtained using a Finometer device while the Stroop color word conflict test was being applied. The electrocardiogram was recorded to obtain the Cornell product as indication of left ventricular mass. The CIMT was measured and the cross-sectional wall area (CSWA) calculated.

RESULTS

African men showed higher total vascular resistance resting values as well as higher positive reactivity values compared with Caucasian men. The SV decreased significantly during stress in African men while resting blood pressure and the Cornell product value increased. SV showed a consistent association with left ventricular mass (β = -0.21; P = 0.04) and CSWA (β = -0.24; P = 0.01) in single and multiple regression analyses. No such associations were evident in the Caucasian men.

CONCLUSIONS

African men showed a suppressed SV, possibly as a result of an increased ventricular afterload leading to end-organ damage.

Determining cut-off values for neck circumference as a measure of the metabolic syndrome amongst a South African cohort: the SABPA study

The aim was to determine receiver operating characteristic (ROC) neck circumference (NC) cut offs best associated with the metabolic syndrome (MetS) in a South African cohort. We included 409 urban Africans and Caucasians and stratified them into gender and age groups (25-45 years; 45-65 years). Measurements included anthropometric, fasting overnight urine and biological markers for the MetS (systolic and diastolic blood pressure, glucose, triglycerides, and high density lipoprotein). ROC analysis determined pathological (NC) cut-points of 39 and 35 cm for young and older African men; 32 and 35 cm for young and old African women; 40 and 41 cm for Caucasian men; 34 and 33 cm for Caucasian women. Pathological NC cut-points significantly predicted MetS in all ethnic-gender-age groups except in African women (ORs 2.3-5.4; 95% CI 1.36-16.5). Multiple regression analyses revealed that MetS prevalence and ROC cut-points were not associated with renal impairment in any groups. ROC NC cut-points demonstrated that NC may be used as an additional anthropometric marker to predict the MetS in a South African cohort but not in African women.

The relationship between cortisol, C-reactive protein and hypertension in African and Causcasian women: the POWIRS study

Research on the roles that C-reactive protein (CRP) and other risk factors such as cortisol and obesity play in the diagnosis of cardiovascular disease (CVD) in African and Caucasian women has become increasingly imperative when one considers the prevalence of hypertension in these groups. CRP and cortisol have been associated with an increased prevalence of hypertension and obesity. Cortisol has also been linked with both hypertension and the hypothalamic-pituitary-adrenal (HPA) response. African women have previously presented with an increased vascular reactivity. Conversely, Caucasian women have displayed an increased central cardiac reactivity. We included African (n = 102) and Caucasian (n = 115) women in the study, matched for age and body mass index. Elevated CRP levels were observed in African women compared to Caucasian women. A trend of hypocortisolism was exhibited in both hypertensive ethnic groups. Systolic blood pressure (SBP) and a vascular marker, arterial compliance (Cw), predicted hypertension in African women. Conversely, in Caucasian women, only SBP predicted hypertension. These results suggest the apparently diverse roles that dysregulation by the HPA axis, in conjunction with the respective cardiac and vascular responses in both Caucasian and African women, can play in future cardiovascular risk for these groups.

Four-Year Trends in Cardiometabolic Risk Factors according to Baseline Abdominal Obesity Status in West-African Adults: The Benin Study

The study examined whether abdominal obesity (AO) according to waist circumference was associated with more unfavourable changes in other cardiometabolic risk (CMR) factors in sub-Saharan Africans. The study included 541 randomly selected and apparently healthy subjects (50% women) aged 25-60 years. Complete data at baseline, 24, and 48 months later was available in 366 subjects. AO was associated with higher CMR at baseline and over the follow-up period, except for high blood pressure. A significantly higher incidence of high ratio of total cholesterol : HDL-cholesterol (TC/HDL-C) was associated with AO. Controlling for WC changes, age, baseline diet, and lifestyles, the relative risk (RR) of low HDL-C and high TC/HDL-C was 3.2 (95% CI 1.06-9.61) and 7.4 (95% CI 2.01-25.79), respectively, in AO men; the RR was not significant in women. Over a four-year period, AO therefore appeared associated with an adverse evolution of cholesterolemia in the study population.

Autonomic responses to stress in Black versus Caucasian Africans: the SABPA study

Underlying mechanisms of increased pressor responses to stress in Blacks are poorly understood. Cardiovascular regulation of normotensive Black (n=43) and Caucasian (n=90) Africans was studied during a cold pressor and color-word conflict test. Autonomic evaluation was performed by spectral analysis. Higher diastolic pressor and heart rate responses to the cold pressor test were observed in Black compared to Caucasian Africans. Autonomic efferent outflow to stress was comparable between groups. Transient downregulation of baroreflex during stress was evident in Blacks but not in Caucasians. Greater diastolic pressor responses were related to a higher cardiac reactivity, a baroreflex desensitization, and higher stress perception in Black Africans. Thus, increased stress perception may facilitate cardiac and diastolic hyperreactivity, indirectly affecting baroreflex function in Black Africans.

The waist circumference of risk in black South african men is lower than in men of European ancestry

BACKGROUND

Central obesity measured by waist circumference is a cardiovascular disease (CVD) risk factor; however, the waist circumference of risk in populations of African descent has not been identified. The International Diabetes Federation currently suggests that cutoffs established in men of European descent be applied to sub-Saharan men-a waist circumference ≥94 cm.

SUBJECTS AND METHODS

Participants were 203 South African black men with type 2 diabetes mellitus (T2DM). They were divided into quartiles of waist circumference (>88 cm, 88-94 cm, 95-103 cm, >103 cm). Cardiovascular risk factors, including insulin resistance (IR), measured by modified homeostasis model assessement of IR (HOMA-IR), and the triglycerides-to-high-density lipoprotein cholesterol (TG-to-HDL-C) ratio, were compared across quartiles.

RESULTS

Age, duration of diabetes, glycosylated hemoglobin (HbA1c), blood pressure, urinary albumin excretion, and smoking were similar across waist circumference quartiles. Overall, for both lipids and measures of IR, there was variation across waist circumference quartiles, but no significant differences between quartiles 2 and 3. Therefore, data from these two quartiles were pooled. Between the first and second+third (88-103 cm) quartiles, there were significant differences in HDL-C (1.30±0.43, 1.10±0.43 mmol/L, P=0.003), TG (medians 1.10, 1.60 mmol/L P<0.001), low-density lipoprotein cholesterol (LDL-C; 2.40±0.93, 2.85±1.03 mmol/L, P=0.01), non-HDL-C (3.05±1.18, 3.70±1.16 mmol/L, P=0.002), HOMA-IR (medians 0.90, 2.10, P<0.001), and TG-to-HDL-C ratio (medians 0.89, 1.17, P<0.001). Additional comparisons were made between men with waist circumference <90 cm and 90-93 cm. Values for each lipid and for IR parameters were more favorable in the <90-cm group (all P<0.05).

CONCLUSIONS

For black South African diabetic men, CVD risk substantially increased with waist circumference >90 cm. The waist circumference cut point of >94 cm has the potential to misclassify many black South African diabetic men at risk for CVD.

Adipokines and cardiometabolic function: How are they interlinked?

OBJECTIVE

Adipokines contribute directly to the coexistence of insulin resistance and endothelial dysfunction. Most studies focus on a single adipokine. We therefore investigated the independent relationships of leptin, adiponectin, tumor necrosis factor-alpha, resistin and visfatin, as well as the gut hormone ghrelin with blood pressure and insulin resistance. Secondly we evaluated the interrelationships of adipokines and ghrelin in concert with various cardiometabolic markers.

METHODS AND RESULTS

Caucasian women (N=115) with varying levels of obesity (aged 31.3 + or - 9.18 years) were included. Significant correlations of leptin, adiponectin, ghrelin and visfatin with mean arterial pressure (p<0.05) disappeared after adjustment for age, body mass index and waist circumference. But significant correlations with insulin resistance (HOMA) (for leptin, adiponectin and ghrelin) remained significant after adjustments. Factor analyses yielded five factors, but two main clusters, namely a metabolic syndrome cluster (including leptin, adiponectin and ghrelin) and a vascular atherosclerotic cluster (including tumor necrosis factor-alpha, visfatin and resistin).

CONCLUSION

Factor analyses identified patterns which indicate specific roles of the various adipokines. Leptin, adiponectin and ghrelin were more closely related to insulin resistance and central obesity as core components of the metabolic syndrome. Visfatin, tumor necrosis factor-alpha and resistin seem to direct their effects onto the vascular system possibly by means of mechanisms such as inflammation, vasoconstriction and coagulation.

Ethnic-specific correlations of visfatin with circulating markers of endothelial inflammation and function

Sub-Saharan Africa is afflicted by high hypertension prevalence that is expected to rise even further along with increasing obesity rates. The present study aimed to investigate the role of visfatin in obesity and to explore associations of visfatin with markers of endothelial function and hemodynamics in African women compared to a well-matched white sample. The present study involved urban African (n = 102) and white (n = 115) women from South Africa, individually matched for age and BMI. We measured blood pressure, cardiac output, and arterial compliance noninvasively, and analyzed visfatin as well as circulating markers of vascular function and inflammation in serum. Serum visfatin concentration did not differ between African and white women. Visfatin was unrelated to obesity in African women but positive associations for total and abdominal obesity were found in white women. Age- and obesity-adjusted univariate and multivariate analyses revealed significant positive associations of visfatin with endothelin-1 and fibrinogen in African women. Identical analyses in white women indicated a positive association of visfatin with C-reactive protein and von Willebrand factor. Our findings suggest a possible role of visfatin in the cardiovascular system that seems to be independent of obesity in the African women.