Body fat distribution and flow-mediated endothelium-dependent vasodilation in older men

Trajectories of body mass index and risk for coronary heart disease: A 38-year follow-up study

Objective

Obesity is a well-known risk factor for coronary heart disease (CHD), but there is little evidence on the effect of long-term trajectories of body mass index (BMI) over the life course. By using repeated assessments, the aim was to study the risk of CHD in adults during 38 years in different trajectories of BMI.

Methods

A sample of 2129 men and women, aged 20–59 years at baseline, took part in four repeated interviews between 1980 and 2005. Data on BMI, medical history, lifestyle and socioeconomy were collected. Based on the World Health Organization categories of BMI, life course trajectories of stable normal weight, stable overweight, stable obesity, increasing BMI and fluctuating BMI were created. The individuals were followed through national registers for first hospitalization of CHD (389 events) until the end of 2017, and Hazard Ratios (HRs) were calculated, adjusted for age, sex, socioeconomic factors, lifestyle factors and metabolic comorbidities.

Results

Stable normal weight in all assessments was the reference group. Those who had an increase in BMI from normal weight in the first assessment to overweight or obesity in later assessments had no increased risk of CHD, HR 1.04 (95% CI: 0.70–1.53). The HR for individuals with fluctuating BMI was 1.25 (0.97–1.61), for stable overweight 1.43 (1.03–1.98), for stable obesity 1.50 (0.92–2.55), and for stable overweight or obesity 1.45 (1.07–1.97), after full adjustments.

Conclusion

Having a stable overweight or obesity throughout adult life was associated with increased CHD risk but changing from normal weight at baseline to overweight or obesity was not associated with increased CHD risk. Prevention of obesity early in life may be particularly important to reduce CHD risk.

Association Between Waist-to-Height Ratio and Endothelial Dysfunction in Patients With Morbidity - A Report From the FMD-J Study

BACKGROUND

Waist circumference (WC), waist-to-height ratio (WHtR) and body mass index (BMI) are known as easy anthropometric markers of abnormal obesity and screening tools for predicting cardiovascular outcomes, but which indices are best is unclear. We therefore investigated the superiority and association between each index and low flow-mediated dilatation (FMD) as a surrogate marker for cardiovascular outcomes in patients with morbidity in a large Japanese prospective cohort.Methods and Results:A total of 1,645 Japanese patients who had coronary artery disease and hypertension or diabetes mellitus were enrolled, and 1,087 of them were analyzed. The high-WHtR group (≥0.5) showed greater morbidity and increased inflammation in association with atherosclerosis compared with the low-WHtR group. High WHtR and advanced age were identified as predictors of low FMD (odds ratio (OR) 1.39, 95% confidence interval (CI) 1.02-1.88, P=0.037 and OR 1.55, 95% CI 1.19-2.01, P=0.001, respectively). However, WC was not associated with that risk in either sex (male: OR 1.37, 95% CI 0.97-1.93, P=0.076; female: OR 1.08, 95% CI 0.68-1.73, P=0.74), and no association was evident between high BMI and low FMD (OR 0.92, 95% CI 0.71-1.19, P=0.54).

CONCLUSIONS

WHtR offers a superior predictor of decreased FMD than other anthropometric indices, and progression of arteriosclerosis might be detected more sensitively. Further study is needed to investigate the relationship between cardiovascular mortality and WHtR.

The effects of obesity and non-pharmacological weight loss on vascular and ventricular function and structure

AIMS

The mechanisms by which obesity confers increased cardiovascular risk and the effects of moderate weight loss on cardiovascular health are incompletely understood. We sought to characterize the preclinical changes in cardiac and vascular health that accompany obesity and the influence of lifestyle modification on these parameters.

METHODS

Preclinical markers of vasculopathy in resistance vessels and conduit arteries and left ventricular structure and function were assessed in 39 obese subjects (BMI > 30 kg/m(2)) and 11 healthy weight controls. The influence of serum on cellular adhesion molecule (CAM) expression on human endothelial cells was studied ex vivo in a subgroup of 13 obese and nine healthy weight subjects. These analyses were repeated in all 17 of the obese subjects who complied with 4-9 months of lifestyle modification treatment (six with weight loss >5% and 11 with weight loss <5%).

RESULTS

Compared with healthy weight controls, obese subjects had decreased peak hyperaemic forearm blood flow (p = 0.015), increased carotid intima-media thickness (p = 0.009), increased left ventricular wall thickness and volume and evidence of systolic and diastolic dysfunction as assessed using tissue Doppler imaging (S', p = 0.09; E'/A', p = 0.02), and serum from obese subjects increased the intercellular CAM-1 expression on human endothelial cells (p = 0.009). However, arterial endothelial function assessed by flow-mediated dilatation was not altered (p = 0.99). Lifestyle modification treatment resulted in potentially beneficial changes in fibrinogen (p = 0.003), HDL cholesterol (p = 0.05) and soluble vascular CAM-1 (p = 0.06). In subjects with weight loss greater than 5% of body weight, there was also a decrease in low-level inflammation (high-sensitivity C-reactive protein, p = 0.05), lipid peroxidation (thiobarbituric acid-reactive substances, p = 0.05) and triglycerides (p = 0.07).

CONCLUSIONS

Obesity is associated with widespread alterations in cardiac and vascular structure and function. Moderate short-term weight loss by lifestyle modification results in some beneficial changes in serum profile; however, these are not accompanied by significant alterations to either cardiac or vascular structure and function.

Relation of cumulative weight burden to vascular endothelial dysfunction in obesity

Although excess fat mass is linked to increased cardiovascular risk, the relation between vascular phenotype and degree of obesity in high weight categories is unknown. We examined brachial artery vasomotor responses using ultrasound in 203 consecutive patients with severe obesity (mean age 44 +/- 11 years; body mass index [BMI] 46 +/- 9 kg/m(2), range 30 to 72; and body weight 128 +/- 29 kg, range 69 to 207). We studied a unique population in which 71% of subjects were characterized as morbidly obese (BMI > or =40 kg/m(2)), which included a 31% group of super-obese subjects (BMI > or =50 kg/m(2)). Brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation were examined as measures of endothelium-dependent and -independent dilation, respectively, in relation to clinical, hemodynamic, and metabolic variables. Endothelial function was significantly impaired in the highest compared with the lowest tertile of body weight (FMD 6.5 +/- 4.6% vs 9.8 +/- 4.8%, p <0.001), whereas nitroglycerin-mediated dilation was similar in all groups. Univariate correlates of FMD were gender, weight, waist circumference, BMI, diastolic blood pressure, and creatinine. In multivariate analysis, weight was a strong independent significant predictor of FMD (beta = -0.23, p = 0.005) in addition to gender. Within an overweight population, cumulative weight burden remains strongly linked to progressive arterial dysfunction. In conclusion, these results suggest that cardiovascular risks intensify with higher degrees of obesity and underscore the importance of therapeutic weight loss interventions.

Fat distribution and endothelial function in normal-overweight menopausal women

BACKGROUND

Adipose tissue is not an inert deposit of fat; in the truncal area, it seems to be metabolically active, due to the adipokines produced locally. These substances are related to insulin resistance, inflammation and atherosclerotic damage to the vascular system. The development of ultrasound methodologies enable better estimation of fat distribution and more detailed investigation of the metabolic aspects of the fat depots and their impact on the initial stages of atherosclerosis.

AIM OF THE STUDY

To investigate the influence of abdominal fat on endothelial function, the initial stages of atherosclerotic vascular damage and its relationship with inflammatory status in normal-overweight subjects [n. 162, body mass index (BMI) >25 kg/m(2) to <30 kg/m(2)].

METHODS

A total of 162 Caucasian postmenopausal women (mean age 54 +/- 4 years, menopausal age 8 +/- 4 years) were subdivided on the basis of the median value of the visceral fat distribution and associations with brachial flow-mediated vasoactivity (FMV), BMI, intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), total and LDL cholesterol investigated.

RESULTS

Subjects with lower levels of visceral fat had a higher brachial FMV (7.9 +/- 4.3 vs. 5.1 +/- 3.2%, P < 0.05) and lower BMI, waist, sICAM-1, sVCAM-1, total and LDL cholesterol. In univariate analyses, abdominal visceral fat showed a direct correlation with sICAM-1 (r = 0.43, P < 0.001), and an inverse correlation with FMV (r = -0.49, P < 0.01). Moreover an indirect relationship emerged between brachial FMV and sICAM-levels (r = -0.36, P < 0.05). In a multivariate analysis the predictive variables for brachial FMV were LDL cholesterol (beta = -0.22, P < 0.05), visceral fat (beta = -0.32, P < 0.05), sICAM-1 (beta = -0.18, P < 0.05), HDL cholesterol (beta = 0.25, P < 0.05) and brachial diameter (beta = -0.27, P < 0.05). Subcutaneous fat and triglycerides were also included in the model.

CONCLUSIONS

In Caucasian normal-overweight women, visceral fat thickness was directly associated with the level of soluble ICAM-1 and inversely with FMV, thereby showing its relevance to endothelial function and the inflammatory state.

The relative impact of different measures of adiposity on markers of early atherosclerosis

BACKGROUND

Although there are several methods available to assess adiposity, there is still controversy on the relative clinical utility of each of these methods. This study examines the relative impact of different measures of adiposity on markers of early atherosclerosis. In particular weight changes over time have been poorly assessed in this setting.

METHODS

Eighty-six healthy individuals (31 men, age 36.5+/-8.9 years) with a wide range of body-mass index (28.7+/-7.0, 18.9-57.9 kg/m2) without hypertension, diabetes or smoking were examined. In addition to waist circumference and waist-to-hip ratio self-reported weight change since adolescence was also calculated. Ultrasonography was used to measure abdominal fat layers and their ratio. Flow-mediated dilatation of the brachial artery, serum levels of intercellular adhesion molecule (sICAM-1) and mean intima-media thickness of the carotid artery were measured as markers of early atherosclerosis.

RESULTS

Stepwise multivariate regression analysis showed waist circumference and waist-to-hip ratio as the only independent predictor of flow-mediated dilatation. Waist circumference and weight change but not current body-mass index were independent predictors of intima-media thickness. These correlations were not influenced by ultrasonographically measured fat layers, C-reactive protein and basal insulin resistance. Body-mass index and weight gain were associated with sICAM-1 but not independently of basal insulin resistance and C-reactive protein.

CONCLUSIONS

Waist circumference and weight gain were the strongest predictors of early atherosclerosis in a population of apparently healthy adults. The ultrasonographically measured fat layers did not provide additional information in this population.

Vasodilation and visceral fat in elderly subjects: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

BACKGROUND

Although obesity has long been recognised as a cardiovascular risk factor, only in recent years has the role of visceral adipose tissue (VAT) been evaluated. In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, we related VAT and other obesity indices to endothelium-dependent vasodilation in both capacitance and resistance arteries.

METHODS AND RESULTS

In this population-based study, 1016 subjects aged 70 were evaluated by the invasive forearm technique with acetylcholine (EDV) and brachial artery ultrasound to assess flow-mediated vasodilation (FMD). Intra-abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) were determined by magnetic resonance imaging in a random sample of 287 subjects. EDV, but not FMD, was inversely related to VAT, SAT, BMI and the waist/hip ratio (r=-0.23, -0.16, -0.21 and -0.11, respectively, p=0.05-0.001 after adjustment for gender). In multiple regression analysis however, only VAT was an independent predictor of EDV. Similar results were obtained for endothelium-independent vasodilation (EIDV, infusion of sodium nitroprusside in the brachial artery).

CONCLUSIONS

Both endothelium-dependent and independent vasodilation in the forearm resistance arteries, but not FMD in the brachial artery, was reduced in elderly subjects with increased intra-abdominal adipose tissue mass. This finding suggests deterioration in general vasoreactivity mainly in resistance arteries in elderly subjects with intra-abdominal obesity.

Effects of acquired obesity on endothelial function in monozygotic twins

OBJECTIVE

To determine whether acquired obesity or accompanying metabolic changes such as adiponectin deficiency, insulin resistance, dyslipidemia, or visceral fat are associated, independent of genetic influences, with endothelial dysfunction by studying young adult monozygotic (MZ) twin pairs discordant for obesity.

RESEARCH METHODS AND PROCEDURES

Nine obesity-discordant (intra-pair difference in BMI, 3.8 to 10.1 kg/m(2)) and nine concordant (0 to 2.3 kg/m(2)) 24- to 27-year-old MZ twin pairs were identified from a population-based FinnTwin16-sample. Endothelial function was measured by blood flow responses to intrabrachial infusions of an endothelium-dependent (acetylcholine) and an endothelium-independent (sodium nitroprusside) vasodilator. Whole body insulin sensitivity was measured using the euglycemic insulin clamp technique, and forearm and body composition were measured with magnetic resonance imaging and DXA. In addition, serum levels of adiponectin, high-sensitivity C-reactive protein, and lipids were determined.

RESULTS

The heavier co-twins of the discordant pairs had significantly lower whole body insulin sensitivity than the leaner co-twins. Blood flows/muscle volume during infusions of acetylcholine and sodium nitroprusside were not altered by obesity. However, intra-pair differences in serum adiponectin, intra-abdominal fat, and C-reactive protein were significantly correlated with those in endothelial function. Only the relationship between intra-pair differences in adiponectin and endothelial function persisted in multiple linear regression analysis. Obesity-concordant co-twins had comparable insulin sensitivity and endothelial function.

DISCUSSION

In young adult MZ twins discordant for obesity, acquired adiponectin deficiency rather than obesity per se is an independent correlate of endothelial dysfunction.

Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism

Obesity is becoming a global epidemic in both children and adults. It is associated with numerous comorbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, obesity is an independent risk factor for CVD, and CVD risks have also been documented in obese children. Obesity is associated with an increased risk of morbidity and mortality as well as reduced life expectancy. Health service use and medical costs associated with obesity and related diseases have risen dramatically and are expected to continue to rise. Besides an altered metabolic profile, a variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amounts, even in the absence of comorbidities. Hence, obesity may affect the heart through its influence on known risk factors such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, obstructive sleep apnea/hypoventilation, and the prothrombotic state, in addition to as-yet-unrecognized mechanisms. On the whole, overweight and obesity predispose to or are associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death because of their impact on the cardiovascular system. The pathophysiology of these entities that are linked to obesity will be discussed. However, the cardiovascular clinical evaluation of obese patients may be limited because of the morphology of the individual. In this statement, we review the available evidence of the impact of obesity on CVD with emphasis on the evaluation of cardiac structure and function in obese patients and the effect of weight loss on the cardiovascular system.

Enhanced cutaneous vascular response in AD subjects under donepezil therapy

OBJECTIVE

Abnormal cutaneous vasodilatory responses to the iontophoresis of vasodilators were previously observed in Alzheimer's disease (AD). We sought to replicate these observations and further identify peripheral vascular components of AD pathology.

METHODS

Methacholine chloride (MCh), acetylcholine chloride (ACh), and sodium nitroprusside (SNP) were applied iontophoretically to forearm skin. Laser Doppler imaging of treated areas yielded total perfusion response values.

RESULTS

Response to MCh was enhanced 78% ( P=0.003 ) in AD subjects under therapy with the acetylcholinesterase inhibitor (AChEI) donepezil ( N=9 ), relative to age- and sex-matched controls ( N=12 ). Significant increases in perfusion were also observed after application of ACh (68%, P=0.03 ) and SNP (46%, P=0.04 ).

CONCLUSIONS

A previous study reported attenuated response to ACh in AD. Paradoxically, we observed a substantially enhanced response that is likely a consequence of donepezil therapy. The increased response to the endothelium-independent vasodilator SNP indicates improved general vasodilatory response, perhaps due to preservation of endogenous ACh by donepezil. Cerebral perfusion in response to functional activation may be improved in this way, suggesting a secondary therapeutic mode of donepezil.

Protein kinase betaII in Zucker obese rats compromises oxygen and flow-mediated regulation of nitric oxide formation

In severe obesity, microvascular endothelial regulation of nitric oxide (NO) formation is compromised in response to muscarinic stimulation, and major arteries have suppressed flow-mediated dilation. Because normal microvessels are highly dependent on flow-mediated stimulation of NO generation and are responsive to intra- and extravascular oxygen availability, they are likely a major site of impaired endothelial regulation. This study evaluated the blood flow and oxygen-dependent aspects of intestinal microvascular regulation and NO production in Zucker obese rats just before the onset of hyperglycemia. Ruboxistaurin (LY-333531) was used to inhibit PKC-betaII to determine whether flow or oxygen-related NO regulation was improved. Blood flow velocity was increased by forcing arterioles to perfuse approximately 50% larger tissue areas by occlusion of nearby arterioles, and oxygen tension in the bath was lowered to create a modest oxygen depletion. When compared with lean Zucker rats, the periarteriolar NO concentration ([NO]) for obese rats was approximately 30% below normal. At elevated shear rates, the [NO] for arterioles of obese animals was 20-30% below those in the arterioles of lean rats, and the NO response to decreased oxygen was about half normal in obese rats. All of these regulatory problems were essentially corrected in obese rats by PKC blockade with only minor changes in the microvascular behavior in lean rats. Therefore, activation of PKC-betaII in endothelial cells during obesity suppressed NO regulation both at rest and in response to increased flow velocity and decreased oxygen availability.