Body fat distribution, blood pressure, and hypertension. A prospective cohort study of men in the normative aging study

Impact of an active lifestyle on cardiovascular autonomic modulation and oxidative stress in males with overweight and parental history of hypertension

Family history of hypertension is associated with early autonomic dysfunction and increased oxidative stress. These alterations have been found to be reinforced by the overweight factor. Conversely, an active lifestyle is effective in improving the mechanisms regulating blood pressure control. Hence, we ought to investigate the effects of an active lifestyle on the hemodynamic, autonomic and oxidative stress parameters in individuals carrying both family history of hypertension and overweight risk factors. Fifty-six normotensive males were divided into four groups: eutrophic offspring of normotensive parents (EN, n = 12), eutrophic and inactive with hypertensive parents (EH, n = 14), overweight and inactive with hypertensive parents (OH, n = 13), and overweight and physically active with hypertensive parents (OAH, n = 17). Cardiovascular autonomic modulation was assessed by heart rate (HRV) and blood pressure (BPV) variability indexes. Oxidative stress included pro/antioxidant markers and nitrite concentration. Inactive offspring of hypertensive parents (EH and OH) showed higher LFSBP (vs EN), an indicator of sympathetic outflow to the vasculature and reduced anti-oxidant activity (vs EN), while higher pro-oxidant markers were found exclusively in OH (vs EN and EH). Conversely, the OAH group showed bradycardia, higher vagally-mediated HFabs index (vs OH and EN), lower sympathovagal balance (vs OH) and preserved LFSBP. Yet, the OAH showed preserved pro/antioxidant markers and nitrite levels. Our findings indicates that overweight offspring of hypertensive parents with an active lifestyle have improved hemodynamic, cardiac autonomic modulation and oxidative stress parameters compared to their inactive peers.

Mechanisms and treatment of obesity-related hypertension-Part 1: Mechanisms

The prevalence of obesity has tripled over the past five decades. Obesity, especially visceral obesity, is closely related to hypertension, increasing the risk of primary (essential) hypertension by 65%-75%. Hypertension is a major risk factor for cardiovascular disease, the leading cause of death worldwide, and its prevalence is rapidly increasing following the pandemic rise in obesity. Although the causal relationship between obesity and high blood pressure (BP) is well established, the detailed mechanisms for such association are still under research. For more than 30 years sympathetic nervous system (SNS) and kidney sodium reabsorption activation, secondary to insulin resistance and compensatory hyperinsulinemia, have been considered as primary mediators of elevated BP in obesity. However, experimental and clinical data show that severe insulin resistance and hyperinsulinemia can occur in the absence of elevated BP, challenging the causal relationship between insulin resistance and hyperinsulinemia as the key factor linking obesity to hypertension. The purpose of Part 1 of this review is to summarize the available data on recently emerging mechanisms believed to contribute to obesity-related hypertension through increased sodium reabsorption and volume expansion, such as: physical compression of the kidney by perirenal/intrarenal fat and overactivation of the systemic/renal SNS and the renin-angiotensin-aldosterone system. The role of hyperleptinemia, impaired chemoreceptor and baroreceptor reflexes, and increased perivascular fat is also discussed. Specifically targeting these mechanisms may pave the way for a new therapeutic intervention in the treatment of obesity-related hypertension in the context of 'precision medicine' principles, which will be discussed in Part 2.

The utilization of BMI in patients with high WHtR as to cardiovascular risk

Introduction: A waist to height ratio (WHtR) greater than 0.5 may be a global screening tool for cardiovascular disease (CVD) and diabetes. However, it is unclear whether WHtR could be used instead of BMI. This study aimed to evaluate the role of BMI regarding CVD and diabetes in a subset of Turkish adults with WHtR greater than 0.5. Material and Method: The cross-sectional study involved 118 participants with WHtR>0.5, 18 years and older who applied to the endocrinology and metabolism disease outpatient clinic between September 2019 and February 2020. WHtR and BMI were calculated. Results: The prevalence of hypertension and hyperlipidemia increased with BMI. WHtR was correlated with FBG. BMI was significantly associated with TG, HDL-c, SBP, and DBP in linear regression analysis, but not with FBG. On the other hand, there was a significant association between WHtR and FBG. Conclusion: This study confirmed that the simple value of ‘0.5’ for WHtR was associated with diabetes risk. The cut-off value of 35 for BMI was effective categorizing participants with high blood pressure and lipid levels in paticipants with high WHtR. Further population-based studies in Turkish adults are needed to evaluate whether WHtR could be used independent from BMI as an early warning of cardiovascular risks for preventive interventions.

Identification of genetic loci simultaneously associated with multiple cardiometabolic traits

BACKGROUND AND AIMS

Cardiometabolic disorders (CMD) arise from a constellation of features such as increased adiposity, hyperlipidemia, hypertension and compromised glucose control. Many genetic loci have shown associations with individual CMD-related traits, but no investigations have focused on simultaneously identifying loci showing associations across all domains. We therefore sought to identify loci associated with risk across seven continuous CMD-related traits.

METHODS AND RESULTS

We conducted separate genome-wide association studies (GWAS) for systolic and diastolic blood pressure (SBP/DBP), hemoglobin A1c (HbA1c), low- and high- density lipoprotein cholesterol (LDL-C/HDL-C), waist-to-hip-ratio (WHR), and triglycerides (TGs) in the UK Biobank (N = 356,574-456,823). Multiple loci reached genome-wide levels of significance (N = 145-333) for each trait, but only four loci (in/near VEGFA, GRB14-COBLL1, KLF14, and RGS19-OPRL1) were associated with risk across all seven traits (P < 5 × 10^-8). We sought replication of these four loci in an independent set of seven trait-specific GWAS meta-analyses. GRB14-COBLL1 showed the most consistent replication, revealing nominally significant associations (P < 0.05) with all traits except DBP.

CONCLUSIONS

Our analyses suggest that very few loci are associated in the same direction of risk with traits representing the full spectrum of CMD features. We identified four such loci, and an understanding of the pathways between these loci and CMD risk may eventually identify factors that can be used to identify pathologic disturbances that represent broadly beneficial therapeutic targets.

Waist circumference was associated with 2-year blood pressure change in community dwelling adults independently of BMI

OBJECTIVE

The present study aimed to analyze the association of 2-year changes in BMI and waist circumference with changes in blood pressure (BP) in a randomized sample of community-dwelling adults.

METHODS

A sample of 331 middle-aged and older adults (mean age of 59.6 ± 17.3 years) was randomly selected. Measurements of SBP and DBP, BMI, and waist circumference were collected at baseline and after 2-year follow-up. Chronological age, sex, socioeconomic status, ethnicity, and self-reported medical diagnosis and use of medication for hypertension, diabetes, and high low-density lipoprotein-cholesterol were covariates. Multiple linear regression models were adopted for statistical analysis.

RESULTS

SBP was positively associated with BMI (β = 0.48, P = 0.013) and waist circumference (β = 0.21, P = 0.005) at baseline and only with waist circumference at follow-up (β = 0.20, P = 0.007). DBP was positively associated with BMI (β = 0.31, P = 0.009) and waist circumference (β = 0.12, P = 0.006) values at baseline and at follow-up (BMI β = 0.42, P = 0.001; waist circumference β = 0.18, P = 0.001). Only the 2-year changes in waist circumference were associated to changes in SBP (β = 0.33, P = 0.013), regardless of confounding factors and BMI.

CONCLUSION

It is suggested that waist circumference is the main factor for control over the time in strategies focused on BP management in adult population.

Solar Activity Is Associated With Diastolic and Systolic Blood Pressure in Elderly Adults

Background

Since solar activity and related geomagnetic disturbances modulate autonomic nervous system activity, we hypothesized that these events would be associated with blood pressure (BP).

Methods and Results

We studied 675 elderly men from the Normative Aging Study (Boston, MA) with 1949 BP measurements between 2000 and 2017. Mixed‐effects regression models were used to investigate the association of average 1‐day (ie, day of BP measurement) to 28‐day interplanetary magnetic field intensity, sunspot number, and a dichotomized measure of global geomagnetic activity (K_p index) in 4‐day increments with diastolic and systolic BP. We adjusted for meteorological conditions and other covariates associated with BP, and in additional models adjusted for ambient air pollutants (particulate matter with an aerodynamic diameter ≤2.5 µm, black carbon, and particle number) and ambient particle radioactivity. There were positive associations between interplanetary magnetic field, sunspot number, and K_p index and BP that were greatest with these exposures averaged over 16 through 28 days before BP measurement. An interquartile range increase of 16‐day interplanetary magnetic field and sunspot number and higher K_p index were associated with a 2.5 (95% CI, 1.7‒3.2), 2.8 (95% CI, 2.1‒3.4), and 1.7 (95% CI, 0.8‒2.5) mm Hg increase, respectively, for diastolic BP as well as a 2.1 (95% CI, 0.7‒3.6), 2.7 (95% CI, 1.5‒4.0), and 0.4 (95% CI, −1.2 to 2.1) mm Hg increase, respectively, for systolic BP. Associations remained after adjustment for ambient air pollutants and ambient particle radioactivity.

Conclusions

Solar activity and solar‐driven geomagnetic disturbances were positively associated with BP, suggesting that these natural phenomena influence BP in elderly men.

Correlation Between the Distribution of Abdominal, Pericardial and Subcutaneous Fat and Muscle and Age and Gender in a Middle-Aged and Elderly Population

OBJECTIVE

The present study aimed to explore the relationships between the distribution of abdominal fat and muscle and age and gender in a middle-aged and elderly population.

METHODS

The levels of abdominal (visceral and subcutaneous) fat, pericardial fat, and psoas major muscle were measured in subjects who had physical examinations at the Health and Medical Department of Peking Union Medical College Hospital from July 2019 to June 2020. The relationship between fat in different areas (ie, different types of fat) and the relationship between different types of fat and the psoas major muscle were investigated in the context of different genders and ages.

RESULTS

The distribution of fat and muscle differed between males and females of the middle-aged and elderly study sample. Volumes of pericardial fat, total abdominal fat, and visceral fat were significantly lower in females than in males, and the area of the psoas major muscle was also significantly lower in females than in males. Levels of subcutaneous fat and total abdominal fat showed no significant correlation with age. The level of muscle showed a significant negative correlation with age.

CONCLUSION

1) Within the middle-aged and elderly sample, male subjects had higher levels than females of all types of fat except for abdominal subcutaneous fat, and had higher levels of psoas muscle than females. 2) Pericardial fat increased with age, whereas levels of abdominal fat did not change significantly with age. 3) The area of psoas major muscle appears to be positively correlated with volumes of all types of fat: subjects with more fat tended to have higher levels of psoas major muscle.

Effects of Blood Pressure Lowering Agents on Cardiovascular Outcomes in Weight Excess Patients: A Systematic Review and Meta-analysis

BACKGROUND

Obesity hypertension is an ongoing pandemic. The first-line medications to treat this condition are still subject to debate. We compared diuretics, calcium-channel blockers (CCB), beta-blockers (BB), angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) as an initial antihypertensive therapy for prevention of cardiovascular morbimortality of hypertensive individuals who are overweight or obese.

METHODS

We conducted a search of the literature for randomized clinical trials in which at least 50% of the participants were overweight or obese. The primary outcomes were all-cause mortality, cardiovascular mortality, acute myocardial infarction (MI), heart failure (HF), stroke, or end-stage renal disease.

RESULTS

Our search yielded 16 randomized studies. Comparisons of two classes of drugs with at least two studies indicated that (1) CCB and ACEI increased the risk of HF [relative risk (RR) = 2.26; 95% confidence interval (CI) 1.16-4.40] and stroke [hazard ratio (HR) = 1.13; 1.00-1.26]), respectively, compared to diuretics; and (2) CCB showed a reduction in stroke (HR = 0.77; 0.66-0.89) and total mortality (HR = 0.94; 0.87-1.01) compared to the BB atenolol. Comparisons of two classes of antihypertensive medications with only one study showed that the risk of MI was higher with ARB valsartan versus CCB (HR = 1.19; 95% CI 1.02-1.38, p = 0.02). In contrast, losartan lowered the risk of a composite cardiovascular outcome compared to atenolol (HR = 0.87; 95% CI 0.77-0.98, p = 0.02).

CONCLUSIONS

In hypertensive subjects with excess weight, diuretics are more effective for preventing HF and stroke than CCB and ACEI, respectively. CCB are a good first-line choice for prevention of cardiovascular disease, except HF.

Visceral Fat: Culprit or Canary?

Although visceral fat is strongly correlated with the metabolic complications of obesity, the existing data indicate it is not the cause of these complications. Excess release of free fatty acids (FFA) from adipose tissue lipolysis can account for a sizable portion of the metabolic complications of obesity. In humans, upper-body subcutaneous adipose tissue accounts for most systemic FFA, whereas visceral fat contributes a modest portion of the excess amount to which the liver is exposed. This pattern is maintained in upper-body/visceral obesity, except that greater amounts of visceral fat expose the liver to more FFA from visceral adipose tissue lipolysis.

Association between body mass index (BMI) and hypertension in south Asian population: evidence from nationally-representative surveys

BACKGROUND

Although there has been a well-established association between overweight-obesity and hypertension, whether such associations are heterogeneous for South Asian populations, or for different socioeconomic groups is not well-known. We explored the associations of overweight and obesity using South Asian cut-offs with hypertension, and also examined the relationships between body mass index (BMI) and hypertension in various socioeconomic subgroups.

METHODS

We analysed the recent Demographic and Health Survey (DHS) data from Bangladesh, India, and Nepal, with a total of 821,040 men and women. Hypertension was defined by 2017 ACC/AHA cut-offs and by Joint National Committee 7 (JNC7) cut-offs for measured blood pressure and overweight and obesity were defined by measured height and weight. We used multiple logistic regressions to estimate the odds ratios (ORs) with 95% confidence intervals (CIs) of hypertension for overweight and obesity as well as for each 5-unit increase in BMI.

RESULTS

The prevalence of hypertension using JNC7 cut-offs among participants increased by age in all three countries. The prevalence ranged from 17.4% in 35-44 years to 34.9% in ≥55 years in Bangladesh, from 4.6% in 18-24 years to 28.6% in 45-54 years in India, and from 3.8% in 18-24 years to 39.2% in ≥55 years in Nepal. Men were more likely to be hypertensive than women in India and Nepal, but not in Bangladesh. Overweight and obesity using both WHO and South Asian cut-offs were associated with higher odds of hypertension in all countries. For each 5 kg/m2 increase in BMI, the ORs for hypertension were 1.79 (95% CI: 1.65-1.93), 1.59 (95% CI: 1.58-1.61), and 2.03 (95% CI: 1.90-2.16) in Bangladesh, India, and Nepal, respectively. The associations between BMI and hypertension were consistent across various subgroups defined by sex, age, urbanicity, educational attainment and household's wealth index.

CONCLUSIONS

Our study shows that the association of BMI with hypertension is stronger for South Asian populations at even lower cut-offs points for overweight and obesity. Therefore, public health measures to reduce population-level reduction in BMI in all population groups would also help in lowering the burden of hypertension.

The comparison of percent body fat estimated by different anthropometrics to predict the incidence of hypertension

Percent body fat (%BF) is associated with the development of hypertension. However, the power of %BF estimated by different anthropometrics to predict incident hypertension was unknown. This study was from the China Health and Nutrition Survey (CHNS). %BF was calculated using the equations with BMI, WC, and skinfold thickness and divided into low and high %BF according to ROC. Cox regression was employed to evaluate the power of different %BFs to predict the development of hypertension. When not adjusting for covariates, %BFs defined by BMI, WC, and ST were the significant predictors of the development of hypertension (all P < 0.0001; crude HR: 2.238, 3.243, and 1.574; and HR 95% CI: 2.098-2.387, 2.905-3.619, and 1.464-1.692). When three %BFs entered into model simultaneously, the significance in %BF estimated by ST disappeared (P = 0.0765; adjusted HR: 1.124; and HR 95% CI: 0.988-1.280). For males, %BFs by BMI, WC, and ST significantly affected the incidence of hypertension as they were separately analyzed (all P < 0.0001; crude HR: 2.445, 2.335, and 1.828; and HR 95% CI: 2.220-2.693, 2.011-2.712, and 1.636-2.042, respectively). For females, %BFs estimated by BMI, WC, and ST were the determinants of the development of hypertension whether covariates were adjusted or not (all P < 0.0001). In conclusion, there was a poor and ineffective association of %BF estimated by triceps skinfold thickness with the development of hypertension, especially when three %BFs were analyzed together. High %BFs estimated by BMI and WC were the true and effective predictors of the incidence of hypertension.

Different anthropometric indicators of central obesity can predict hypertension in older adults

Objective: to investigate the association between hypertension and anthropometric indicators of central obesity, obtained from two anatomical sites in older adults.Methodology: cross-sectional study that involved 145 older adults, from whom socioeconomic and demographic data and anthropometric indicators of central obesity (waist circumference [CC] and abdominal circumference [CA]) were obtained, which were considered independent variables. A logistic regression model was used to analyze associations and for the discriminatory power of the cut-off points of the hypertension anthropometric indicators, receiver operating characteristic (ROC) curve was performed. Comparisons were made between ROC curves, with the aim of identifying significant differences in the discriminatory power of the anthropometric indicators studied.Results: out of the 145 individuals, 79 were females (54%) and 66 males (46%). Results showed a high prevalence of arterial hypertension in men (69,7%) and women (73,4%). Both CC and CA were significantly associated with hypertension in both genders. Parameters of the ROC curve revealed that both anthropometric indicators of central obesity exhibit good discriminatory power for hypertension in the studied population. The cut-off point for CC was > 83,2 cm for men and > 82,6 cm for women; while for CA it was > 85,1 cm and > 85,4 cm for men and women, respectively.Conclusion: CA and CC are significantly associated with hypertension in both genders, and there is no superiority between them to predict hypertension in the elderly population.

Sociodemographic Characteristics, Dietary Practices, and Nutritional Status of Adults with Hypertension in a Semi-Rural Community in the Eastern Region of Ghana

Introduction

Hypertension is a major contributor to the global disease burden and mortality. Evidence suggests increasing hypertension prevalence in Ghana but there is limited public awareness and information on the characteristics of those with the disease.

Objective

To describe the baseline characteristics of adults with hypertension who were randomized to receive either hypertension related nutrition education plus hospital-based standard of care or only the standard of care (control group) in Asesewa, a semi-rural community in the Eastern Region of Ghana. Only baseline data were used in the present analysis.

Methods

A cross-sectional baseline survey was completed for 63 adults with confirmed hypertension diagnosis. Data on sociodemographic characteristics and diet were obtained through interviews and participants' body mass index (BMI) was computed. Pearson chi-square statistic was used to assess differences between those with both elevated diastolic blood pressure (DBP) and systolic blood pressure (SBP) and those with only elevated SBP.

Results

Mean ± SD age of participants was 54.5±13.8 years. Approximately 71% of participants had both elevated SBP (>140 mmHg) and DBP (>90 mmHg) while the remaining 29% had only elevated SBP. The median number of times the food groups beneficial to hypertension management were consumed in the preceding week to the interview was 1 for green leafy vegetables, 1 for dairy products, 2 for fruits, and 4 for legumes. The median number of times for consuming harmful food groups was 3 for salted fish and 7 times for fats and oils. Signifcantly more participants in the age group above 50 than the younger participants had elevated SBP (83.3 vs. 16.7:P=0.027) and those with BMI equal to or greater than 25 were more likely to have both elevated SBP and DBP (P=0.047).

Conclusions

Findings from this study have implications for the prevention and management of hypertension in this semi-rural population.

Antiangiogenic Herbal Composition Ob-X Reduces Abdominal Visceral Fat in Humans: A Randomized, Double-Blind, Placebo-Controlled Study

Adipose tissue growth is angiogenesis-dependent, and angiogenesis inhibitors can regulate adipose tissue mass by cutting off the blood supply. We examined whether antiangiogenic herbal composition Ob-X can reduce fast-growing abdominal fat, especially visceral fat in humans by inhibiting angiogenesis. Eighty abdominally obese subjects (body mass index: 25-29.9 kg/m², waist circumference: exceeding 90 cm for males and 85 cm for females) participated in a 12-week randomized, double-blind, placebo-controlled human study to evaluate the efficacy and safety of Ob-X. 690 mg of Ob-X was administered orally twice a day. The Ob-X group showed a noticeable reduction in visceral fat of 20.5% after the 12-week treatment as compared to baseline measured by computed tomography. The change in visceral fat in the Ob-X group was statistically significant as compared to the placebo group (p = 0.0495) and 1.9 times higher than in the placebo group. Therefore, angiogenesis inhibitor Ob-X has the potential to improve obesity-related metabolic syndrome by reducing dangerous visceral fat.

Body mass index, abdominal adiposity, weight gain and risk of developing hypertension: a systematic review and dose-response meta-analysis of more than 2.3 million participants

OBJECTIVE

This study aimed to test the association between anthropometric measures and risk of developing hypertension.

METHODS

We did a systematic search using PubMed and Scopus, from inception up to January 2017. Prospective cohort studies reporting the risk estimates of hypertension for three or more quantitative categories of indices of general and abdominal adiposity were included. Summary relative risks were calculated using random-effects models.

RESULTS

Fifty-seven prospective cohort studies were included. Summary relative risks were 1.49 (95% confidence interval [CI]: 1.41, 1.58; I²  = 97.4%, n = 50) for a five-unit increment in body mass index, 1.27 (95%CI: 1.15, 1.39; I²  = 95.0%, n = 14) for a 10-cm increment in waist circumference, 1.16 (95%CI: 1.09, 1.23; I²  = 77.8%, n = 5) for weight gain equal to a one-unit increment in BMI, and 1.37 (95%CI: 1.24, 1.51; I²  = 76.4%, n = 8) and 1.74 (95%CI: 1.35, 2.13; I²  = 58.9%, n = 4) for a 0.1-unit increment in waist-to-hip ratio and waist-to-height ratio, respectively. The risk of hypertension increased continuously with increasing all anthropometric measures, and also along with weight gain.

CONCLUSION

Being as lean as possible within the normal body mass index range may be the best suggestion in relation to primary prevention of hypertension.

Impact of hypercortisolism on skeletal muscle mass and adipose tissue mass in patients with adrenal adenomas

CONTEXT

Abdominal visceral adiposity and central sarcopenia are markers of increased cardiovascular risk and mortality.

OBJECTIVE

To assess whether central sarcopenia and adiposity can serve as a marker of disease severity in patients with adrenal adenomas and glucocorticoid secretory autonomy.

DESIGN

Retrospective cohort study.

PATIENTS

Twenty-five patients with overt Cushing's syndrome (CS), 48 patients with mild autonomous cortisol excess (MACE) and 32 patients with a nonfunctioning adrenal tumour (NFAT) were included.

METHODS

Medical records were reviewed, and body composition measurements (visceral fat [VAT], subcutaneous fat [SAT], visceral/total fat [V/T], visceral/subcutaneous [V/S] and total abdominal muscle mass) were calculated based on abdominal computed tomography (CT).

RESULTS

In patients with overt CS, when compared to patients with NFAT, the V/T fat and the V/S ratio were increased by 0.08 (P < .001) and by 0.3 (P < .001); however, these measurements were decreased by 0.04 (P = .007) and 0.2 (P = .01), respectively, in patients with MACE. Total muscle mass was decreased by -10 cm² (P = .02) in patients with overt CS compared to patients with NFAT. Correlation with morning serum cortisol concentrations after dexamethasone suppression testing revealed that for every 28 nmol/L cortisol increase there was a 0.008 increase in V/T (P < .001), 0.02 increase in the V/S fat ratio (P < .001) and a 1.2 cm² decrease in mean total muscle mass (P = .002).

CONCLUSIONS

The severity of hypercortisolism was correlated with lower muscle mass and higher visceral adiposity. These CT-based markers may allow for a more reliable and objective assessment of glucocorticoid-related disease severity in patients with adrenal adenomas.

Association of triglycerides and new lipid markers with the incidence of hypertension in a Spanish cohort

OBJECTIVE

Triglycerides and high-density lipoprotein cholesterol (HDL-C) are known to be risk factors for cardiovascular disease. However, there has been limited knowledge on the relationship between triglycerides and incident hypertension. The associations of incident hypertension with triglycerides and triglycerides-related indices such as triglycerides to HDL-C ratio (TG/HDL-C) and triglyceride-glucose index (TyG) were evaluated.

METHODS

Data from 3637 participants from the Vascular Metabolic Clinica Universidad Navarra cohort were followed-up during a mean of 8.49 years. A Cox proportional hazard ratio with repeated measures analyses was performed to assess the risk of developing hypertension across the quintiles of triglycerides, TG/HDL-C ratio, and TyG index.

RESULTS

The risk of developing hypertension was 47% and 73% greater for those in the fourth and fifth quintiles of triglycerides, after adjusting for age, sex, BMI, cigarette smoking, daily alcohol intake, lifestyle pattern, type 2 diabetes, antiaggregation therapy, low-density lipoprotein cholesterol, SBP, and DBP. In men, those in the top quintile of triglycerides, TG/HDL-C ratio or TyG index were two times more likely to develop hypertension than those in the bottom quintile. In women, the effect was attenuated although the risk of hypertension rose with increasing quintiles (P for trend <0.05). The results were consistent when analyses were restricted to those participants without diabetes and obesity at baseline.

CONCLUSIONS

Our results evidenced the associations between triglycerides-related variables and incident hypertension independently of adiposity. This association was stronger than those observed for other commonly used lipid parameters or lipid ratios, such as the TC/HDL-C ratio.

VIDEO ABSTRACT

: http://links.lww.com/HJH/A620.

Utility of the Visceral Adiposity Index and Hypertriglyceridemic Waist Phenotype for Predicting Incident Hypertension

BACKGROUND

The aim of this study was to assess the utility of the visceral adiposity index (VAI) and the hypertriglyceridemic waist (HTGW) phenotype as possible hypertension (HTN) predictors in a high-risk population without diabetes and HTN.

METHODS

Incident HTN over a 7-year follow-up was assessed among 1,375 first-degree non-diabetic and non-hypertensive relatives of consecutive patients with type 2 diabetes who were 30 to 70 years of age. HTN was defined as a blood pressure reading ≥140/90 mm Hg or the use of antihypertensive medications. We examined the incidence of HTN across VAI quintiles and four groups defined according to baseline fasting serum triglyceride (TG) levels and waist circumference (WC).

RESULTS

The VAI and the HTGW phenotype at baseline were related to an increased risk for HTN. In comparison with the lowest VAI quintile, the highest VAI quintile showed a significant associated with HTN in an age- and gender-adjusted model (odds ratio [OR], 1.65; 95% confidence interval [CI], 1.07 to 2.55). Those with HTGW were 2.3 times (OR, 2.27; 95% CI, 1.54 to 3.35) more likely to develop HTN than those with a normal WC and normal TG levels.

CONCLUSION

Greater VAI values weakly predicted HTN, whereas the HTGW phenotype was a stronger predictor of incident HTN in an Iranian high-risk population.

Adiponectin protects against incident hypertension independent of body fat distribution: observations from the Dallas Heart Study

BACKGROUND

Excess adipose tissue has been implicated in the pathogenesis of insulin resistance and atherosclerosis and is a key risk factor for blood pressure (BP) elevation. However, circulating levels of adiponectin, a protein produced by adipose tissue and widely implicated in the pathogenesis of insulin resistance and atherosclerosis, are inversely proportional to adiposity. The relationship between adiponectin and incident hypertension has not been determined in the general US population.

METHODS

Normotensive participants (n = 1233) enrolled in the Dallas Heart Study, a multiethnic, probability-based population sample of Dallas County adults were followed for median of 7 years. Retroperitoneal, intraperitoneal, visceral, and subcutaneous adipose tissue were measured at baseline by magnetic resonance imaging. Liver fat content was measured by ¹ H-magnetic resonance spectroscopy. Relative risk regression was used to determine the association of adiponectin with incident hypertension after adjustment for age, race, sex, BMI, smoking, diabetes, baseline systolic BP, total cholesterol, and regional fat depot.

RESULTS

Of the 1233 study participants (median age 40 years, 40% black, and 56% women), 391 (32%) had developed hypertension over a median follow-up of 7 years. Adiponectin levels were associated with reduced risk of incident hypertension (RR 0.81, 95% CI [0.68-0.96]) in the fully adjusted model, which included liver fat. Similar results were observed after adjustment for subcutaneous or visceral fat depots when tested individually or simultaneously in the model.

CONCLUSION

Our study suggested a protective role of adiponectin against incident hypertension independent of body fat distribution.

Utility of ultrasound for body fat assessment: validity and reliability compared to a multicompartment criterion

Measurement of body composition to assess health risk and prevention is expanding. Accurate portable techniques are needed to facilitate use in clinical settings. This study evaluated the accuracy and repeatability of a portable ultrasound (US) in comparison with a four-compartment criterion for per cent body fat (%Fat) in overweight/obese adults. Fifty-one participants (mean ± SD; age: 37·2 ± 11·3 years; BMI: 31·6 ± 5·2 kg m^-2 ) were measured for %Fat using US (GE Logiq-e) and skinfolds. A subset of 36 participants completed a second day of the same measurements, to determine reliability. US and skinfold %Fat were calculated using the seven-site Jackson-Pollock equation. The Wang 4C model was used as the criterion method for %Fat. Compared to a gold standard criterion, US %Fat (36·4 ± 11·8%; P = 0·001; standard error of estimate [SEE] = 3·5%) was significantly higher than the criterion (33·0 ± 8·0%), but not different than skinfolds (35·3 ± 5·9%; P = 0·836; SEE = 4·5%). US resulted in good reliability, with no significant differences from Day 1 (39·95 ± 15·37%) to Day 2 (40·01 ± 15·42%). Relative consistency was 0·96, and standard error of measure was 0·94%. Although US overpredicted %Fat compared to the criterion, a moderate SEE for US is suggestive of a practical assessment tool in overweight individuals. %Fat differences reported from these field-based techniques are less than reported by other single-measurement laboratory methods and therefore may have utility in a clinical setting. This technique may also accurately track changes.

Relations of body weight status in early adulthood and weight changes until middle age with hypertension in the Chinese population

We conducted a retrospective cohort study of adult participants from the China Multicenter Collaborative Study of Cardiovascular Epidemiology to explore the relationship between early adulthood weight status, body weight change from age 25 to middle age and hypertension in the Chinese population. Self-reported weight was used to calculate the body mass index (BMI) at age 25. The association between BMI at age 25, subsequent weight change and hypertension was examined using a logistic regression model. Of the 14 635 study participants sampled in 1998, 3525 were diagnosed with hypertension. After adjusting for age, sex and other potential confounding factors, both the BMI at age 25 and weight gain were positively associated with the risk of hypertension (P for trend <0.001). Weight loss could more effectively reduce the risk of hypertension for participants with a higher BMI (BMI⩾24 kg m^-2) at age 25 than for those who experienced a weight change of -2.5-2.5 kg. The odds ratio (OR) and 95% confidence interval (CI) for a weight change of -7.5 to -2.6 kg were 0.63 (0.46-0.86); for a weight change of <-7.5 kg, these statistics were 0.45 (0.32-0.63). For participants who had a lower BMI (18.5-20.9 kg m^-2) at age 25, the OR and 95% CI were 0.86 (0.58-1.26) for a weight change of -7.5 to -2.6 kg and 0.95 (0.44-2.05) for a weight change of <-7.5 kg. Being overweight and obesity in early adulthood and adult weight gain were both independently associated with marked increase in the risk of hypertension in middle-aged men and women. Weight loss may be a protective factor against hypertension for people who were overweight or obese in early adulthood.

Strong independent association between obesity and essential hypertension

Obesity and hypertension (HTN) are major risk factors for cardiovascular disease. Association between obesity and HTN has not been studied in a large populations following adjustment for comorbidities. The goal of this study was to evaluate any association between obesity and HTN after adjusting for baseline characteristics. We used ICD-9 codes for obesity and HTN from the Nationwide Inpatient Sample (NIS) databases. Two randomly selected years, 1992 and 2002, were chosen from the databases as two independent samples. We used uni- and multivariable analysis to study any correlation between obesity and HTN. The 1992 database contained a total of 6,195,744 patients. HTN was present in 37.2 % of patients with obesity versus 12% of the control group (OR: 4.36, CI 4.30-4.42, P < 0.001). The 2002 database contained a total of 7,153,982 patients. HTN was present in 50.7% of patients with obesity versus 25.6% of the control group (OR: 2.98, CI 2.96-3.00, P < 0.001). Using multivariable analysis adjusting for gender, hyperlipidaemia, age, smoking, type 2 diabetes and chronic renal failure, obesity remained correlated with HTN in both years (1992: OR 2.69, CI 2.67-2.72, P < 0.001; 2002: OR 2.98, CI 2.96-3.00, P < 0.001). The presence of obesity was found to be strongly and independently associated with HTN. The cause of this correlation is not known warranting further investigation.

Development of hypertension in overweight adolescents: a review

The upward trend in adolescent hypertension is widely attributed to the adolescent obesity epidemic. Secular trends in adolescent prehypertension and hypertension have risen in congruence with increasing trends in the prevalence of overweight and obesity. The correlation between body mass index and blood pressure in adolescence is moderate to strong in most studies and strongest in those classified as overweight or obese. The mechanisms relating to the development of hypertension in overweight adolescents are unclear; however, a number of nonmodifiable and modifiable factors have been implicated. Importantly, certain clinical and biochemical markers in overweight adolescents are indicative of high risk for hypertension, including family history of hypertension and hyperinsulinemia. These characteristics may prove useful in stratifying overweight adolescents as high or low risk of comorbid hypertension. The treatment of overweight and obesity related hypertension in this population focuses on two key modalities: lifestyle change and pharmacotherapy. These approaches focus almost exclusively on weight reduction; however, a number of emerging strategies target hypertension more specifically. Among adolescents with overt hypertension there are also several factors that indicate higher risk of concurrent subclinical disease, persistent adult hypertension, and adult cardiovascular disease. This group may benefit substantially from more aggressive pharmacological treatments. Limitations in the literature relate to the paucity of studies reporting specific effects for the adolescent age group of overweight and obese individuals. Nonetheless, intervention for adiposity-related hypertension in adolescence may partially mitigate some of the cardiovascular risk in adulthood.

Obesity associated Lyplal1 gene is regulated in diet induced obesity but not required for adipocyte differentiation

Obesity and its associated morbidities represent one of the major and most rapidly expanding health epidemics in the world. Recent genome-wide association studies (GWAS) have identified several variants in LYPLAL1 gene that are significantly associated with central obesity preferentially in females. However, the exact function of this gene in adipose tissue development and obesity remains completely uncharacterized. We found murine Lyplal1 gene demonstrated a depot and sex-specific expression profile in white adipose tissues (WAT), and was significantly reduced in the epididymal and retroperitoneal fats in a murine model of high fat diet induced obesity (DIO). Lyplal1 mRNA was mildly up-regulated during adipogenesis and enriched in mature adipocytes through a PPARγ-independent mechanism. However, overexpression and knockdown of Lyplal1 did not significantly perturb adipocyte differentiation, triacylglycerol accumulation and/or insulin signaling. These data highlight a depot-specific marked reduction of Lyplal1 transcripts in diet induced obesity but a dispensable role of Lyplal1 in adipose tissue development.

Sex and sex steroids: impact on the kinetics of fatty acids underlying body shape

Adult humans have a remarkable sexual dimorphism in body shape. Men tend to store relatively more fat in the upper body whereas women store more fat in the lower body. We do not have a complete understanding of the mechanisms underlying these differences, but we know that people who preferentially store abdominal fat are at greater risk of metabolic disease. It is also known that the changes in sex steroid concentrations during puberty and again with advancing age are accompanied by changes in body fat distribution. The objective of this review is to describe what has been learned regarding the mechanisms underlying changes in regional body fat distribution that occur as a result of changes in sex hormones and to delineate effects of sex steroids in modulating body composition.

The Sexual Dimorphism of Lipid Kinetics in Humans

In addition to the obvious differences in body shape, there are substantial differences in lipid metabolism between men and women. These differences include how dietary fatty acids are handled, the secretion and clearance of very low-density lipoprotein-triglycerides, the release rates of free fatty acids (FFA) from adipose tissue relative to energy needs, and the removal of FFA from the circulation, including the storage of FFA into adipose tissue via the direct uptake process. We will review what is known about these processes and how they may contribute to the sexual dimorphism of body fat distribution.

Interplay of overweight and insulin resistance on hypertension development

OBJECTIVES

Obesity and hypertension are associated, possibly through causal pathways involving insulin resistance and metabolic derangements. We aimed to investigate in a whites sample if overweight or obese persons without insulin resistance are at risk of developing hypertension or blood pressure progression.

METHODS

In a meta-analysis, using multivariable-adjusted mixed-effects logistic regression models, we investigated the risks of hypertension development and blood pressure progression by combinations of relative weight classes and presence or absence of insulin resistance (defined as highest vs. lower three quartiles using the homeostatic model assessment method) in the Uppsala Longitudinal Study of Adult Men (n = 2322) and the Prospective Investigation of the Vasculature in Uppsala Seniors studies (n = 1066). These two samples, consisting mainly of middle-aged and elderly men, provided 1846 observations for the development of hypertension in normotensive individuals and 4223 observations for progressing to a higher blood pressure stage.

RESULTS

During a median of 10 years of follow-up, 884 (47.9%) developed hypertension and 1639 (38.8%) progressed to a higher blood pressure stage. Overweight or obese persons without insulin resistance had an increased risk of hypertension development [odds ratio (OR) 1.46, 95% confidence interval 1.14-1.88] and blood pressure progression (OR 1.32, 1.10-1.59) compared with normal-weight persons without insulin resistance.

CONCLUSION

According to this study, being overweight or obese without insulin resistance increases the risk of hypertension and blood pressure progression. This adds to the evidence that overweight and obesity may be harmful per se, and that overweight and obesity without glucometabolic derangements are not benign conditions.

The relationship of body mass and fat distribution with incident hypertension: observations from the Dallas Heart Study

BACKGROUND

Obesity has been linked to the development of hypertension, but whether total adiposity or site-specific fat accumulation underpins this relationship is unclear.

OBJECTIVES

This study sought to determine the relationship between adipose tissue distribution and incident hypertension.

METHODS

Normotensive participants enrolled in the Dallas Heart Study were followed for a median of 7 years for the development of hypertension (systolic blood pressure [SBP] ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or initiation of blood pressure medications). Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) was quantified by magnetic resonance imaging and proton-spectroscopic imaging, and lower body fat (LBF) was imaged by dual-energy x-ray absorptiometry. Multivariable relative risk regression was performed to test the association between individual fat depots and incident hypertension, adjusting for age, sex, race/ethnicity, diabetes, smoking, SBP, and body mass index (BMI).

RESULTS

Among 903 participants (median age, 40 years; 57% women; 60% nonwhite; median BMI 27.5 kg/m(2)), 230 (25%) developed incident hypertension. In multivariable analyses, higher BMI was significantly associated with incident hypertension (relative risk: 1.24; 95% confidence interval: 1.12 to 1.36, per 1-SD increase). However, when VAT, SAT, and LBF were added to the model, only VAT remained independently associated with incident hypertension (relative risk: 1.22; 95% confidence interval: 1.06 to 1.39, per 1-SD increase).

CONCLUSIONS

Increased visceral adiposity, but not total or subcutaneous adiposity, was robustly associated with incident hypertension. Additional studies will be needed to elucidate the mechanisms behind this association.

The pathophysiology of hypertension in patients with obesity

The combination of obesity and hypertension is associated with high morbidity and mortality because it leads to cardiovascular and kidney disease. Potential mechanisms linking obesity to hypertension include dietary factors, metabolic, endothelial and vascular dysfunction, neuroendocrine imbalances, sodium retention, glomerular hyperfiltration, proteinuria, and maladaptive immune and inflammatory responses. Visceral adipose tissue also becomes resistant to insulin and leptin and is the site of altered secretion of molecules and hormones such as adiponectin, leptin, resistin, TNF and IL-6, which exacerbate obesity-associated cardiovascular disease. Accumulating evidence also suggests that the gut microbiome is important for modulating these mechanisms. Uric acid and altered incretin or dipeptidyl peptidase 4 activity further contribute to the development of hypertension in obesity. The pathophysiology of obesity-related hypertension is especially relevant to premenopausal women with obesity and type 2 diabetes mellitus who are at high risk of developing arterial stiffness and endothelial dysfunction. In this Review we discuss the relationship between obesity and hypertension with special emphasis on potential mechanisms and therapeutic targeting that might be used in a clinical setting.

Obesity induces neuroinflammation mediated by altered expression of the renin-angiotensin system in mouse forebrain nuclei

Obesity is a widespread health concern that is associated with an increased prevalence of hypertension and cardiovascular disease. Both obesity and hypertension have independently been associated with increased levels of inflammatory cytokines and immune cells within specific brain regions, as well as increased activity of the renin-angiotensin system (RAS). To test the hypothesis that high-fat diet (HFD) induced obesity leads to an angiotensin-II (Ang-II)-dependent increase in inflammatory cells within specific forebrain regions that are important for cardiovascular regulation, we first assessed microglial activation, astrocyte activation, inflammation and RAS component gene expression within selected metabolic and cardiovascular control centers of the forebrain in adult male C57BL/6 mice given either a HFD or a low-fat diet (LFD) for 8weeks. Subsequently, we assessed the necessity of the paraventricular nucleus of the hypothalamus (PVN) angiotensin type-1a (AT1a) receptor for these responses by using the Cre/lox system in mice to selectively delete the AT1a receptor from the PVN. These studies reveal that in addition to the arcuate nucleus of the hypothalamus (ARC), the PVN and the subfornical organ (SFO), two brain regions that are known to regulate blood pressure and energy balance, also initiate proinflammatory responses after the consumption of a diet high in fat. They further indicate that some, but not all, of these responses are reversed upon deletion of AT1a specifically within the PVN.

The role of estrogen in adipose tissue metabolism: insights into glucose homeostasis regulation

Adipose tissue is an organ with active endocrine function involved in the regulation of energy balance and glucose homeostasis via multiple metabolic signaling pathways targeting the brain, liver, skeletal muscle, pancreas, and other organs. There is increasing evidence demonstrating that the female sex hormone, estrogen, regulates adipose development and improves systemic glucose homeostasis in both males and females. The underlying mechanism linking estrogenic regulation in adipose tissue and systemic glucose metabolism has not been fully elucidated, but is thought to include interactions of estrogen receptor signaling events involving lipolytic and/or lipogenic enzyme activity, free fatty acid metabolism, and adipocytokine production. Thus, understanding the effects of estrogen replacement on adipose tissue biology and metabolism is important in determining the risk of developing obesity-related metabolic disorders in patients undergoing treatment for sex hormone deficiency. In this report, we review literature regarding the role of estrogens and their corresponding receptors in the control of adipose metabolism and glucose homeostasis in both rodents and humans. We also discuss the effects of selective estrogen receptor modulators on glucose metabolism.

Subcutaneous Adipose Tissue Transplantation in Diet-Induced Obese Mice Attenuates Metabolic Dysregulation While Removal Exacerbates It

Adipose tissue distribution is an important determinant of obesity-related comorbidities. It is well established that central obesity (visceral adipose tissue accumulation) is a risk factor for many adverse health consequences such as dyslipidemia, insulin resistance, and type-2-diabetes. We hypothesize that the metabolic dysregulation that occurs following high fat diet-induced increases in adiposity are due to alterations in visceral adipose tissue function which influence lipid flux to the liver via the portal vein. This metabolic pathology is not exclusively due to increases in visceral adipose tissue mass but also driven by intrinsic characteristics of this particular depot. In Experiment 1, high fat diet (HFD)-induced obese control (abdominal incision, but no fat manipulation) or autologous (excision and subsequent relocation of adipose tissue) subcutaneous tissue transplantation to the visceral cavity. In Experiment 2, mice received control surgery, subcutaneous fat removal, or heterotransplantation (tissue from obese donor) to the visceral cavity. Body composition analysis and glucose tolerance tests were performed 4 weeks postsurgery. Adipose mass and portal adipokines, cytokines, lipids, and insulin were measured from samples collected at 5 weeks postsurgery. Auto- and heterotransplantation in obese mice improved glucose tolerance, decreased systemic insulin concentration, and reduced portal lipids and hepatic triglycerides compared with HFD controls. Heterotransplantation of subcutaneous adipose tissue to the visceral cavity in obese mice restored hepatic insulin sensitivity and reduced insulin and leptin concentrations to chow control levels. Fat removal, however, as an independent procedure exacerbated obesity-induced increases in leptin and insulin concentrations. Overall subcutaneous adipose tissue protects against aspects of metabolic dysregulation in obese mice. Transplantation-induced improvements do not occur via enhanced storage of lipid in adipose tissue, however, altered hepatic lipid regulation may play a contributory role.

The Yo-Yo intermittent recovery test level 1 as a high intensity training tool: aerobic and anaerobic responses

OBJECTIVE

The aim of this study was to investigate the effects of using the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) as a high intensity training tool for sedentary university female students.

METHODS

Baseline measures were recorded for body fat percentage, Wingate Anaerobic Test (WAnT) peak power and mean power, and Yo-Yo IR1 performance. Subjects were matched in pairs for body fat percentage and then randomly allocated to the intervention group (INT) (n=12) or control group (CON) (n=13). The INT undertook a 6-week training programme twice a week using the Yo-Yo IR1. The CON undertook no training.

RESULTS

The INT increased their Yo-Yo IR1 performance (230±38m baseline vs 403±152m post-training), WAnT peak power (970±176 Watts baseline vs 1148±159 Watts post-training), and WAnT mean power (399±55 Watts baseline vs 439±53 Watts post-training) (p<0.05). No changes were observed in the CON (p>0.05).

CONCLUSION

The results of this study show that a 6-week high intensity intermittent training programme using the Yo-Yo IR1 as a training intervention increases both aerobic and anaerobic capacity in a sedentary female population.

Neuroimmune communication in hypertension and obesity: a new therapeutic angle?

Hypertension is an epidemic health concern and a major risk factor for the development of cardiovascular disease. Although there are available treatment strategies for hypertension, numerous hypertensive patients do not have their clinical symptoms under control and it is imperative that new avenues to treat or prevent high blood pressure in these patients are developed. It is well established that increases in sympathetic nervous system (SNS) outflow and enhanced renin-angiotensin system (RAS) activity are common features of hypertension and various pathological conditions that predispose individuals to hypertension. More recently, hypertension has also become recognized as an immune condition and accumulating evidence suggests that interactions between the RAS, SNS and immune systems play a role in blood pressure regulation. This review summarizes what is known about the interconnections between the RAS, SNS and immune systems in the neural regulation of blood pressure. Based on the reviewed studies, a model for RAS/neuroimmune interactions during hypertension is proposed and the therapeutic potential of targeting RAS/neuroimmune interactions in hypertensive patients is discussed. Special emphasis is placed on the applicability of the proposed model to obesity-related hypertension.

Development of a pediatric body mass index using longitudinal single-index models

As a measure of human adiposity, the body mass index, defined as weight/height(2), has been widely used in clinical investigations. For children undergoing pubertal development, whether this function of height and weight represents an optimal way of quantifying body mass for assessing of specific health outcomes has not been carefully studied. In this study, we propose an alternative pediatric body mass measure for prediction of blood pressure based on recorded height and weight data using single-index modeling techniques. Specifically, we present a general form of partially linear single-index mixed effect models for the determination of this new metric. A methodological contribution of this research is the development of an efficient algorithm for the fitting of a general class of partially linear single-index models in longitudinal data situations. The proposed model and related model fitting algorithm are easily implementable in most computational platforms. Simulation demonstrates superior performance of the new method, as compared to the standard body mass index measure. Using the proposed method, we explore an alternative body mass measure for the prediction of blood pressure in children. The method is potentially useful for the construction of other indices for specific investigations.

Obesity-related hypertension: pathogenesis, cardiovascular risk, and treatment--a position paper of the The Obesity Society and The American Society of Hypertension

In light of the worldwide epidemic of obesity, and in recognition of hypertension as a major factor in the cardiovascular morbidity and mortality associated with obesity, The Obesity Society and The American Society of Hypertension agreed to jointly sponsor a position paper on obesity-related hypertension to be published jointly in the journals of each society. The purpose is to inform the members of both societies, as well as practicing clinicians, with a timely review of the association between obesity and high blood pressure, the risk that this association entails, and the options for rational, evidenced-based treatment. The position paper is divided into six sections plus a summary as follows: pathophysiology, epidemiology and cardiovascular risk, the metabolic syndrome, lifestyle management in prevention and treatment, pharmacologic treatment of hypertension in the obese, and the medical and surgical treatment of obesity in obese hypertensive patients.

Obesity-related hypertension: pathogenesis, cardiovascular risk, and treatment: a position paper of The Obesity Society and the American Society of Hypertension

In light of the worldwide epidemic of obesity, and in recognition of hypertension as a major factor in the cardiovascular morbidity and mortality associated with obesity, The Obesity Society and the American Society of Hypertension agreed to jointly sponsor a position paper on obesity-related hypertension to be published jointly in the journals of each society. The purpose is to inform the members of both societies, as well as practicing clinicians, with a timely review of the association between obesity and high blood pressure, the risk that this association entails, and the options for rational, evidenced-based treatment. The position paper is divided into six sections plus a summary as follows: pathophysiology, epidemiology and cardiovascular risk, the metabolic syndrome, lifestyle management in prevention and treatment, pharmacologic treatment of hypertension in the obese, and the medical and surgical treatment of obesity in obese hypertensive patients.

Metabolic alterations following visceral fat removal and expansion: Beyond anatomic location

Increased visceral adiposity is a risk factor for metabolic disorders such as dyslipidemia, hypertension, insulin resistance and type 2 diabetes, whereas peripheral (subcutaneous) obesity is not. Though the specific mechanisms which contribute to these adipose depot differences are unknown, visceral fat accumulation is proposed to result in metabolic dysregulation because of increased effluent, e.g., fatty acids and/or adipokines/cytokines, to the liver via the hepatic portal vein. Pathological significance of visceral fat accumulation is also attributed to adipose depot/adipocyte-specific characteristics, specifically differences in structural, physiologic and metabolic characteristics compared with subcutaneous fat. Fat manipulations, such as removal or transplantation, have been utilized to identify location dependent or independent factors that play a role in metabolic dysregulation. Obesity-induced alterations in adipose tissue function/intrinsic characteristics, but not mass, appear to be responsible for obesity-induced metabolic dysregulation, thus “quality” is more important than “quantity.” This review summarizes the implications of obesity-induced metabolic dysfunction as it relates to anatomic site and inherent adipocyte characteristics.

Single slice vs. volumetric MR assessment of visceral adipose tissue: reliability and validity among the overweight and obese

Visceral adipose tissue (VAT) is associated with abnormal cardiovascular and metabolic profiles. Total VAT volume of the abdominal compartment by magnetic resonance imaging (MRI) is the gold-standard measurement for VAT but is costly and time consuming. Prior studies suggest VAT area on a single slice MR image may serve as a surrogate for total VAT volume but it is unknown if this relationship is maintained in overweight and obese men and women. Untreated sleep apnea subjects enrolled into the Icelandic Sleep Apnea Cohort (ISAC) underwent abdominal MRI. VAT area and subcutaneous adipose tissue (SAT) area at the L2-L3 and L4-L5 interspaces and total VAT and SAT volumes were determined by manual examination using image analysis software; 539 men and 129 women with mean ages of 54.1 and 58.8 years and mean BMI of 32.2 kg/m(2) and 33.7 kg/m(2), respectively, were studied. Mean total VAT volume was 40% smaller and mean total SAT was 25% larger among females compared with males. The correlation with VAT volume was significantly larger for L2-L3 VAT area (r = 0.96) compared to L4-L5 VAT area (r = 0.83). The difference in correlation coefficients was statistically significant (nonparametric bootstrap P < 0.001 with 95% confidence interval (CI) for the difference from 0.11 to 0.15. VAT area at L2-L3 was also significantly better correlated with VAT volume than traditional anthropometric variables. Linear regression analyses demonstrated that L2-L3 area alone was sufficient for predicting total VAT volume and that the nature of the linear association was maintained across all levels of obesity and in both genders.

Plasma adiponectin and the risk of hypertension in white and black postmenopausal women

BACKGROUND

Adiponectin may have a protective role in the development of obesity-related metabolic and vascular disorders, including hypertension. We conducted a prospective, nested case control study to investigate the relation between baseline plasma adiponectin, measures of adiposity, and subsequent risk of hypertension.

METHODS

We selected 400 white and 400 black postmenopausal women, age <70 years, who developed incident hypertension during 5.9-year follow-up and an equal number of age- and race-matched controls in the Women's Health Initiative Observational Study. We measured plasma concentrations of total adiponectin in their baseline blood samples.

RESULTS

In crude matched models, plasma adiponectin was inversely associated with risk of hypertension among both white and black women. The association appeared to be nonlinear in white women but dose related in black women. Adjustment for lifestyle factors, measures of obesity, and obesity-related clinical factors attenuated these associations. The multivariable relative risk (95% CI) of hypertension across increasing quartiles of plasma adiponectin were 1.00, 0.98 (0.66-1.46), 0.63 (0.41-0.97), and 0.92 (0.60-1.42) in white women (P(trend): 0.38) and 1.00, 0.96 (0.64-1.46), 0.83 (0.53-1.29), and 0.58 (0.36-0.94) in black women (P(trend): 0.02). Further adjustment for inflammatory markers and endothelial markers eliminated the association in white, but not black, women.

CONCLUSIONS

In this prospective, nested case control study, we found an inverse association between plasma adiponectin and risk of hypertension in white and black postmenopausal women. The reduced risk of hypertension was limited to only intermediate concentrations of adiponectin in white women whereas it was graded across quartiles of adiponectin in black women.

Genome-wide association for abdominal subcutaneous and visceral adipose reveals a novel locus for visceral fat in women

Body fat distribution, particularly centralized obesity, is associated with metabolic risk above and beyond total adiposity. We performed genome-wide association of abdominal adipose depots quantified using computed tomography (CT) to uncover novel loci for body fat distribution among participants of European ancestry. Subcutaneous and visceral fat were quantified in 5,560 women and 4,997 men from 4 population-based studies. Genome-wide genotyping was performed using standard arrays and imputed to ~2.5 million Hapmap SNPs. Each study performed a genome-wide association analysis of subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), VAT adjusted for body mass index, and VAT/SAT ratio (a metric of the propensity to store fat viscerally as compared to subcutaneously) in the overall sample and in women and men separately. A weighted z-score meta-analysis was conducted. For the VAT/SAT ratio, our most significant p-value was rs11118316 at LYPLAL1 gene (p = 3.1 × 10E-09), previously identified in association with waist-hip ratio. For SAT, the most significant SNP was in the FTO gene (p = 5.9 × 10E-08). Given the known gender differences in body fat distribution, we performed sex-specific analyses. Our most significant finding was for VAT in women, rs1659258 near THNSL2 (p = 1.6 × 10-08), but not men (p = 0.75). Validation of this SNP in the GIANT consortium data demonstrated a similar sex-specific pattern, with observed significance in women (p = 0.006) but not men (p = 0.24) for BMI and waist circumference (p = 0.04 [women], p = 0.49 [men]). Finally, we interrogated our data for the 14 recently published loci for body fat distribution (measured by waist-hip ratio adjusted for BMI); associations were observed at 7 of these loci. In contrast, we observed associations at only 7/32 loci previously identified in association with BMI; the majority of overlap was observed with SAT. Genome-wide association for visceral and subcutaneous fat revealed a SNP for VAT in women. More refined phenotypes for body composition and fat distribution can detect new loci not previously uncovered in large-scale GWAS of anthropometric traits.

Human obesity and endothelium-dependent responsiveness

Obesity is an ongoing worldwide epidemic. Besides being a medical condition in itself, obesity dramatically increases the risk of development of metabolic and cardiovascular disease. This risk appears to stem from multiple abnormalities in adipose tissue function leading to a chronic inflammatory state and to dysregulation of the endocrine and paracrine actions of adipocyte-derived factors. These, in turn, disrupt vascular homeostasis by causing an imbalance between the NO pathway and the endothelin 1 system, with impaired insulin-stimulated endothelium-dependent vasodilation. Importantly, emerging evidence suggests that the vascular dysfunction of obesity is not just limited to the endothelium, but also involves the other layers of the vessel wall. In particular, obesity-related changes in medial smooth muscle cells seem to disrupt the physiological facilitatory action of insulin on the responsiveness to vasodilator stimuli, whereas the adventitia and perivascular fat appear to be a source of pro-inflammatory and vasoactive factors that may contribute to endothelial and smooth muscle cell dysfunction, and to the pathogenesis of vascular disease. While obesity-induced vascular dysfunction appears to be reversible, at least in part, with weight control strategies, these have not proved sufficient to prevent the metabolic and cardiovascular complication of obesity on a large scale. While a number of currently available drugs have shown potentially beneficial vascular effects in patients with obesity and the metabolic syndrome, elucidation of the pathophysiological mechanisms underlying vascular damage in obese patients is necessary to identify additional pharmacologic targets to prevent the cardiovascular complications of obesity, and their human and economic costs.

LINKED ARTICLES

This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.

Improved insulin sensitivity after long-term treatment with AT1 blockers is not associated with PPARγ target gene regulation

In both cell culture experiments and in vivo studies, a number of angiotensin II type 1 (AT(1)) receptor antagonists activated the peroxisome proliferator-activated receptor-γ (PPARγ). This mechanism has been discussed to be, at least in part, responsible for the improvement in glucose metabolism observed in animal studies and clinical trials. To investigate whether the PPARγ-dependent mechanism may represent a valid target for chronic therapy, spontaneously hypertensive rats (SHR) were fed either with a cafeteria diet (CD) or standard chow. CD-fed SHR were simultaneously treated with either telmisartan (TEL; 8 mg/kg(body weight)· d) or candesartan (CAND; 10 mg/kg(body weight)· d) for 3 months because TEL, but not CAND, has been demonstrated to be a strong activator of PPARγ. After 3 months, chow- and CD-fed controls were hypertensive, whereas TEL and CAND treatment resulted in normalized blood pressures in SHR. Body weight and the amount of abdominal fat (determined by magnetic resonance imaging) were higher in CD- than in chow-fed SHR. After TEL or CAND, body weight, abdominal fat quantity, and adipocyte size returned to normal. In glucose tolerance tests, the glucose responses were comparable in the TEL- and CAND-treated SHR and obese controls, whereas the insulin response was almost halved by AT(1) blockade. Expression of PPARγ target genes aP2, FAT CD36, FASn, and PEPCK remained unaltered at the protein level in visceral fat after TEL and CAND compared with the CD-fed controls. Because the expression of examined PPARγ target genes was not affected, we concluded that improved insulin sensitivity after long-term treatment with AT(1) blockers was not related to a PPARγ-dependent mechanism.

Mechanisms linking obesity to hypertension

Obesity-related hypertension is increasingly recognized as a distinct hypertensive phenotype requiring a modified approach to diagnosis and management. In this review rapidly evolving insights into the complex and interdependent mechanisms linking obesity to hypertension are discussed. Overweight and obesity are associated with adipose tissue dysfunction, characterized by enlarged hypertrophied adipocytes, increased infiltration by macrophages and marked changes in secretion of adipokines and free fatty acids. This results in chronic vascular inflammation, oxidative stress, activation of the renin-angiotensin-aldosterone system and sympathetic overdrive, eventually leading to hypertension. These mechanisms may provide novel targets for anti-hypertensive drug treatment. Recognition of obesity-related hypertension as a distinct diagnosis enables tailored therapy in clinical practice. This includes lifestyle modification and accommodated choice of blood pressure-lowering drugs.

Enhanced endothelin-1 system activity with overweight and obesity

Endothelin (ET)-1-mediated vasoconstrictor tone contributes to the development and progression of several adiposity-related conditions, including hypertension and atherosclerotic vascular disease. The aims of the present study were to determine 1) whether endogenous ET-1 vasoconstrictor activity is elevated in overweight and obese adults, and, if so, 2) whether increased ET-1-mediated vasoconstriction contributes to the adiposity-related impairment in endothelium-dependent vasodilation. Seventy-nine adults were studied: 34 normal weight [body mass index (BMI) < 25 kg/m(2)], 22 overweight (BMI ≥ 25 and < 30 kg/m(2)), and 23 obese (BMI ≥ 30 kg/m(2)). Forearm blood flow (FBF) responses to intra-arterial infusion of ET-1 (5 pmol/min for 20 min) and selective ET-1 receptor blockade (BQ-123, 100 nmol/min for 60 min) were determined. In a subset of the study population, FBF responses to ACh (4.0, 8.0, and 16.0 μg·100 ml tissue(-1)·min(-1)) were measured in the absence and presence of selective ET-1 receptor blockade. The vasoconstrictor response to ET-1 was significantly blunted in overweight and obese adults (∼ 70%) compared with normal weight adults. Selective ET-1 receptor blockade elicited a significant vasodilator response (∼ 20%) in overweight and obese adults but did not alter FBF in normal weight adults. Coinfusion of BQ-123 did not affect FBF responses to ACh in normal weight adults but resulted in an ∼ 20% increase (P < 0.05) in ACh-induced vasodilation in overweight and obese adults. These results demonstrate that overweight and obesity are associated with enhanced ET-1-mediated vasoconstriction that contributes to endothelial vasodilator dysfunction and may play a role in the increased prevalence of hypertension with increased adiposity.