Resting metabolic rate and substrate use in obesity hypertension

Resting metabolic rate in obesity

The prevalence of obesity has continued to rise, and obesity and its attendant metabolic disorders are major global health threat factors. Among the current interventions for obesity, none have demonstrated sustained efficacy in achieving long-term outcomes. So, the identification of therapeutic targets is of paramount importance in the advancement and sustainability of obesity. Resting metabolic rate (RMR) constitutes 60%-75% of total energy expenditure and serves a crucial function in maintaining energy balance. Nevertheless, there exists considerable heterogeneity in RMR among individuals. Low RMR is associated with weight gain, elevating the susceptibility to obesity-related ailments. Hence, RMR will be the main focus of interest in the study of obesity treatment. In this review, we will elucidate the influence factors and mechanisms of action of RMR in obesity, with particular emphasis on the effects of obesity treatment on RMR and the alterations and influence factors of RMR in special types of populations with obesity.

Blood pressure, gallstones, and age at first cholecystectomy in U.S. adults: a cross-sectional study

BACKGROUND

Gallstones are a prevalent health issue. Recent studies have revealed that blood pressure (BP) may affect gallstone formation. This study assessed the association between hypertension (HTN) and both the prevalence of gallstones and the age at first cholecystectomy among U.S. adults.

METHODS

Data were extracted from the National Health and Nutrition Examination Survey (NHANES) database from 2017 to 2020. Weighted logistic and linear regression analyses and subgroup analyses were employed to investigate the relationships between HTN, gallstone disease (GD), and age at first cholecystectomy. Additionally, this study employed generalized additive models (GAM) and smooth-fitting curves to delineate the relationships. The two-piecewise linear regression model and logarithmic likelihood ratio test elucidated the inflection point of systolic blood pressure (SBP) on the age at first cholecystectomy.

RESULTS

The study included 7,532 participants aged over 20 years. Of these, 817 reported a history of cholecystectomy, and 781 reported a history of gallstones. After adjustment for age, gender, race, diabetes, and hypercholesterolemia, HTN was significantly associated with gallstones in individuals aged 48 years (OR = 1.39; 95% CI: 1.03, 1.88). SBP was positively correlated with the age at first cholecystectomy (β = 0.20, 95% CI: 0.13, 0.26). When examining the correlation between SBP and age at surgery, age was first positively and then negatively correlated with BP, with 170 as an inflection point. We carried out subgroup analyses to evaluate the robustness of the link between HTN and cholecystectomy. The results revealed a consistent positive association between HTN and cholecystectomy across these variables (p > 0.05).

CONCLUSION

The study found a correlation between BP and the prevalence of gallstones in individuals aged 42 years and older and a positive association between SBP and the age at first cholecystectomy. While causality cannot be confirmed, these findings may assist in identifying early risk groups for GD and early cholecystectomy, thereby enhancing risk stratification and potentially reducing screening costs.

Magnitude of hypertension and its association with obesity among employees of Wallaga University, Ethiopia: a cross-sectional study

OBJECTIVE

To determine the magnitude of hypertension, its association with obesity and the associated factors among employees of Wallaga University, Ethiopia.

DESIGN, SETTING AND PARTICIPANTS

This institution-based cross-sectional study was employed among 588 employees of the university. Respondents were selected by stratified random sampling technique and interviewed with the aid of a structured questionnaire.

THE MAIN OUTCOME MEASURED

Hypertension and obesity were measured using WHO Stepwise approach and recommendations. We used a stratified random sampling technique to select 588 employees of the university from 3 August 2021 to 15 October 2021. A structured questionnaire and anthropometric measurements were used for data collection. Multivariable logistic regression analysis was used to determine factors independently associated with hypertension. A p value less than or equal to 0.05 and its 95% confidence level was used to declare the statistical significance.

RESULTS

A total of 578 participants consented and completed the study, giving a response rate of 98.3%. The mean age of the respondents was 31.78 years with SD of 5.4. The overall prevalence of hypertension, general obesity and central obesity was 14.4% (95% CI 11.6% to 17.5%), 31.3% (95% CI 27.6% to 35.3%) and 37% (95% CI 33.1% to 41.1%), respectively. Obesity was significantly associated with hypertension (adjusted OR (AOR): 6.3; 95% CI 2.60 to 8.19). Age range from 35 to 46 (AOR 7.01; 95% CI 1.56 to 31.74), age ≥46 years (AOR 8.45; 95% CI 1.14 to 62.04), being non-academic staff (AOR 2.74; 95% CI 1.56 to 4.81), having additional income (AOR 2.48; 95% CI 1.08 to 5.70), physical inactivity (AOR 2.36; 95% CI 1.44 to 3.88) and poor practice of dietary salt consumption (AOR 1.65; 95% CI 1.01 to 2.87) were factors associated with hypertension.

CONCLUSION

One in seven, more than two in seven and nearly two in six of the employees of Wallaga University were hypertensive, centrally obese and generally obese, respectively. There was a positive association between obesity and hypertension. Comprehensive awareness creation and devising workplace intervention strategies are highly recommended to reduce the hypertension burden and associated obesity.

A genetic variant of fatty acid amide hydrolase (FAAH) exacerbates hormone-mediated orexigenic feeding in mice

Fatty acid amide hydrolase (FAAH) degrades the endocannabinoid anandamide. A polymorphism in FAAH (FAAH C385A) reduces FAAH expression, increases anandamide levels, and increases the risk of obesity. Nevertheless, some studies have found no association between FAAH C385A and obesity. We investigated whether the environmental context governs the impact of FAAH C385A on metabolic outcomes. Using a C385A knock-in mouse model, we found that FAAH A/A mice are more susceptible to glucocorticoid-induced hyperphagia, weight gain, and activation of hypothalamic AMP-activated protein kinase (AMPK). AMPK inhibition occluded the amplified hyperphagic response to glucocorticoids in FAAH A/A mice. FAAH knockdown exclusively in agouti-related protein (AgRP) neurons mimicked the exaggerated feeding response of FAAH A/A mice to glucocorticoids. FAAH A/A mice likewise presented exaggerated orexigenic responses to ghrelin, while FAAH knockdown in AgRP neurons blunted leptin anorectic responses. Together, the FAAH A/A genotype amplifies orexigenic responses and decreases anorexigenic responses, providing a putative mechanism explaining the diverging human findings.

Motus Vita Est: Fruit Flies Need to Be More Active and Sleep Less to Adapt to Either a Longer or Harder Life

Background: Activity plays a very important role in keeping bodies strong and healthy, slowing senescence, and decreasing morbidity and mortality. Drosophila models of evolution under various selective pressures can be used to examine whether increased activity and decreased sleep duration are associated with the adaptation of this nonhuman species to longer or harder lives. Methods: For several years, descendants of wild flies were reared in a laboratory without and with selection pressure. To maintain the “salt” and “starch” strains, flies from the wild population (called “control”) were reared on two adverse food substrates. The “long-lived” strain was maintained through artificial selection for late reproduction. The 24 h patterns of locomotor activity and sleep in flies from the selected and unselected strains (902 flies in total) were studied in constant darkness for at least, 5 days. Results: Compared to the control flies, flies from the selected strains demonstrated enhanced locomotor activity and reduced sleep duration. The most profound increase in locomotor activity was observed in flies from the starch (short-lived) strain. Additionally, the selection changed the 24 h patterns of locomotor activity and sleep. For instance, the morning and evening peaks of locomotor activity were advanced and delayed, respectively, in flies from the long-lived strain. Conclusion: Flies become more active and sleep less in response to various selection pressures. These beneficial changes in trait values might be relevant to trade-offs among fitness-related traits, such as body weight, fecundity, and longevity.

Factors influencing the progression from prehypertension to hypertension among Chinese middle-aged and older adults: a 2-year longitudinal study

BACKGROUND

This study aimed to investigate the proportion of prehypertension cases progressing to hypertension among Chinese middle-aged and elderly populations over a 2-year period and related influencing factors.

METHODS

Data were obtained from the China Health and Retirement Longitudinal Study, and 2,845 individuals who were ≥ 45 years old and prehypertensive at baseline were followed from 2013-2015. Structured questionnaires were administered, and blood pressure (BP) and anthropometric measurements were performed by trained personnel. Multiple logistic regression analysis was done to investigate factors associated with prehypertension progressing to hypertension.

RESULTS

Over the 2-year follow-up, 28.5% experienced progression of prehypertension to hypertension; this occurred more frequently in men than women (29.7% vs. 27.1%). Among men, older age (55-64 years: adjusted odds ratio [aOR] = 1.414, 95% confidence interval [CI]:1.032-1.938; 65-74 years: aOR = 1.633, 95%CI: 1.132-2.355; ≥ 75 years: aOR = 2.974, 95%CI: 1.748-5.060), obesity (aOR = 1.634, 95%CI: 1.022-2.611), and number of chronic diseases (1: aOR = 1.366, 95%CI: 1.004-1.859; ≥ 2: aOR = 1.568, 95%CI: 1.134-2.169) were risk factors for progression to hypertension whereas being married/cohabiting (aOR = 0.642, 95% CI: 0.418-0.985) was a protective factor. Among women, risk factors included older age (55-64 years: aOR = 1.755, 95%CI: 1.256-2.450; 65-74 years: aOR = 2.430, 95%CI: 1.605-3.678; ≥ 75 years: aOR = 2.037, 95% CI: 1.038-3.995), married/cohabiting (aOR = 1.662, 95%CI: 1.052-2.626), obesity (aOR = 1.874, 95%CI: 1.229-2.857), and longer naps (≥ 30 and < 60 min: aOR = 1.682, 95%CI: 1.072-2.637; ≥ 60 min: aOR = 1.387, 95%CI: 1.019-1.889).

CONCLUSIONS

Chinese middle-aged and elderly individuals experienced a risk of prehypertension progressing to hypertension over a 2-year period, although the influencing factors differed by sex; this should be considered in interventions.

Estimation of Salt Intake in Normotensive and Hypertensive Children: The Role of Body Weight

OBJECTIVE

The connection between increased dietary salt intake and arterial hypertension has been recognized for a long time, even in children. This study aimed to investigate salt consumption in normotensive and hypertensive children and evaluate their dietary habits.

MATERIALS AND METHODS

A total of fifty participants were included in this cross-sectional study: twenty-five normotensive children and 25 children of both sexes with essential arterial hypertension from 12-17 years old. Subjects' body mass index, waist-to-hip ratio, body composition and arterial blood pressure were measured, and their daily salt intake was calculated from 24-h urine samples. Using the food frequency questionnaire (FFQ), the data on the average daily total energy and food intakes were collected and analyzed using a suitable program.

RESULTS

Estimated daily salt intake was significantly higher in hypertensive compared to normotensive children, and this is positively associated with blood pressure and body mass index (BMI). Hypertensive children had significantly higher BMIs, which also positively correlated with blood pressure. Consistently, resting metabolic rate (kcal) is higher in hypertensive children compared to normotensive, and this is also associated with blood pressure. Reported energy intake is also enlarged in hypertensive compared to normotensive children and for both groups, levels are significantly higher than the recommended values.

CONCLUSIONS

Our study results confirm the relationship between daily salt consumption, blood pressure and body weight. Sodium consumption related to blood pressure and body weight among children. Cardiovascular disease prevention should start in early childhood by reducing salt intake and preventing overweight/obesity since these are two of the most important modifiable risk factors for hypertension.

The association between hypertension and the risk of gallstone disease: a cross-sectional study

BACKGROUND

To explore the association between hypertension and the risk of gallstone disease.

METHODS

We collected the data about the subjects receiving physical examination. Gallstone disease was diagnosed by abdominal ultrasound. Multivariable logistic regression was used to study the association between blood pressure and the risk of gallstone disease. SPSS version 23.0 was used for statistical analysis, and two-tailed P < 0.05 was defined as statistically significant.

RESULTS

A total of 318,403 people were included in the study and 171,276 (53.8%) of them were men and 147,127 (46.2%) were women. Among them, 27,463 (8.6%) were diagnosed with gallstone disease on ultrasound examination, with 12,452 (3.9%) cases of gallstones and 15,017 (4.7%) cases of cholecystectomy. Multivariable logistic regression showed that hypertension was significantly associated with the risk of gallstone disease (OR = 1.05; 95% CI: 1.02-1.10; P = 0.03) and gallstones (OR = 1.12; 95% CI: 1.06-1.19; P < 0.01) and the association between hypertension and gallstone disease was stronger in women than in men. However, hypertension was not significantly correlated with cholecystectomy (OR = 0.99; 95% CI: 0.95-1.04; P = 0.85). Additionally, results showed that with the severity of hypertension increased, the risk of gallstone disease was also marked elevated (P for trend < 0.001).

CONCLUSIONS

The gallstone disease was prevalent and hypertension is significantly associated with the gallstone disease risk with a significant dose-response association. This study showed that the association between hypertension and cholecystectomy was not statistically significant, maybe hypertension correlated with gallstones but not with symptomatic gallstone disease which would require cholecystectomy.

Treatment of hypertension with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and resting metabolic rate: A cross-sectional study

Hypertension in obese and overweight patients is associated with an elevated resting metabolic rate (RMR). The aim of this study was to determine whether RMR is reduced in hypertensive patients treated with angiotensin‐converting enzyme inhibitors (ACEI) and blockers (ARB). The RMR was determined by indirect calorimetry in 174 volunteers; 93 (46.5 %) were hypertensive, of which 16 men and 13 women were treated with ACEI/ARB, while 30 men and 19 women with untreated hypertension served as a control group. Treated and untreated hypertensives had similar age, BMI, physical activity, and cardiorespiratory fitness. The RMR normalized to the lean body mass (LBM) was 15% higher in the untreated than ACEI/ARB‐treated hypertensive women (p = .003). After accounting for LBM, whole‐body fat mass, age, the double product (heart rate x systolic blood pressure), and the distance walked per day, the RMR was 2.9% lower in the patients taking ACEI/ARB (p = .26, treatment x sex interaction p = .005). LBM, age, and the double product explained 78% of the variability in RMR (R² = 0.78, p < .001). In contrast, fat mass, the distance walked per day, and total T4 or TSH did not add predictive power to the model. Compared to men, a greater RMR per kg of LBM was observed in untreated hypertensive overweight and obese women, while this sex difference was not observed in patients treated with ACEI or ARBs. In conclusion, our results indicate that elevated RMR per kg of LBM may be normalized by antagonizing the renin‐angiotensin system.

Resting metabolic rate is increased in hypertensive patients with overweight or obesity: Potential mechanisms

The purpose of this investigation was to determine whether differences in body composition, pharmacological treatment, and physical activity explain the increased resting metabolic rate (RMR) and impaired insulin sensitivity in hypertension. Resting blood pressure, RMR (indirect calorimetry), body composition (dual-energy X-ray absorptiometry), physical activity (accelerometry), maximal oxygen uptake (VO₂ max) (ergospirometry), and insulin sensitivity (Matsuda index) were measured in 174 patients (88 men and 86 women; 20-68 years) with overweight or obesity. Hypertension (HTA) was present in 51 men (58%) and 42 women (49%) (p = .29). RMR was 6.9% higher in hypertensives than normotensives (1777 ± 386 and 1663 ± 383 kcal d^-1 , p = .044). The double product (systolic blood pressure × heart rate) was 18% higher in hypertensive than normotensive patients (p < .001). The observed differences in absolute RMR were non-significant after adjusting for total lean mass and total fat mass (estimated means: 1702 kcal d^-1 , CI: 1656-1750; and 1660 kcal d^-1 , CI: 1611-1710 kcal d^-1 , for the hypertensive and normotensive groups, respectively, p = .19, HTA × sex interaction p = .37). Lean mass, the double product, and age were the variables with the higher predictive value of RMR in hypertensive patients. Insulin sensitivity was lower in hypertensive than in normotensive patients, but these differences disappeared after accounting for physical activity and VO_2max . In summary, hypertension is associated with increased RMR and reduced insulin sensitivity. The increased RMR is explained by an elevated myocardial oxygen consumption due to an increased resting double product, combined with differences in body composition between hypertensive and normotensive subjects.

Interplay between Heart Disease and Metabolic Steatosis: A Contemporary Perspective

The liver-heart axis is a growing field of interest owing to rising evidence of complex bidirectional interplay between the two organs. Recent data suggest non-alcoholic fatty liver disease (NAFLD) has a significant, independent association with a wide spectrum of structural and functional cardiac diseases, and seems to worsen cardiovascular disease (CVD) prognosis. Conversely, the effect of cardiac disease on NAFLD is not well studied and data are mostly limited to cardiogenic liver disease. We believe it is important to further investigate the heart-liver relationship because of the tremendous global health and economic burden the two diseases pose, and the impact of such investigations on clinical decision making and management guidelines for both diseases. In this review, we summarize the current knowledge on NAFLD diagnosis, its systemic manifestations, and associations with CVD. More specifically, we review the pathophysiological mechanisms that govern the interplay between NAFLD and CVD and evaluate the relationship between different CVD treatments and NAFLD progression.

Weight change is associated with increased all-cause mortality and non-cardiac mortality among patients with type 2 diabetes mellitus

BACKGROUND

It is unclear whether changes in weight affect subsequent adverse events in patients with type 2 diabetes mellitus (T2DM) already at high risk of cardiovascular disease (CVD).

METHODS AND RESULTS

This is a post hoc analysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study data to examine the relationship between changes in weight and adverse events. Patients were divided into groups based on changes in body mass index (BMI): stable weight, gain or loss of BMI ≤1.5 kg/m²; moderate weight gain, BMI gain of 1.5-5 kg/m²; pronounced weight gain, BMI gain >5 kg/m²; moderate weight loss, BMI loss of 1.5-5 kg/m²; and pronounced weight loss, BMI loss >5 kg/m². The primary endpoint of the present study was all-cause mortality. Secondary endpoints were cardiac death, non-fatal myocardial infarction (MI), and non-cardiac mortality. A total of 9372 T2DM patients with a mean follow-up of 8.08 ± 3.00 years were included for analysis. The average change in weight across the entire study population was 1.80 ± 9.00%, representing ~0.448 ± 2.98 kg/m². Patients with pronounced weight loss had the highest risk of all-cause mortality (hazard ratio (HR) 2.07, 95% confidence interval (CI): 1.68-2.55), followed by patients with pronounced weight gain (HR 1.23, 95% CI: 1.02-1.56); patients with stable weight had the lowest risk. An asymmetric V-shaped relationship was observed between changes in BMI and all-cause mortality and non-cardiac mortality. Although no statistical significance was observed in terms of cardiac death and non-fatal MI, a flat V-shaped relationship may exist.

CONCLUSIONS

Weight was stable in most T2DM patients with high risk of CVD. Weight loss and gain is associated with increased all-cause mortality and non-cardiac mortality. Pronounced weight loss and weight gain is associated with a slight increase in cardiac death and non-fatal MI incidence, which does not reach statistical significance.

Comparison of adiposity indices in relation to prehypertension by age and gender: A community-based survey in Henan, China

BACKGROUND

To compare the efficiency of bioelectrical indices (visceral fat index [VFI], percentage body fat [PBF]) and anthropometric indices (body mass index, waist circumference, waist-to-height ratio, a body shape index ) in the relation to prehypertension (120-139/80-89 mm Hg) among the Chinese population.

METHODS

Using stratified multistage random sampling method, a general population-based sample of 11 175 adults in Henan province were selected from 2013 to 2015. The individuals were divided into three categories by blood pressure levels: normotension (<120 and 80 mm Hg), stage 1 prehypertension (120-129/80-84 mm Hg) and stage 2 prehypertension (130-139/85-89 mm Hg).

RESULTS

VFI and PBF tended to increase with age in men and women. However, for each age-specific group, men tended to have higher VFI than women (all P < 0.01) and women tended to have greater PBF (all P < 0.0001). The odds ratios (OR) and area under the receiver operating characteristic curves for prehypertension associated with adiposity indices declined with age. VFI and PBF showed higher standardized adjusted ORs for prehypertension in young (~40 years) men (VFI: 2.02-3.05; PBF: 1.82-2.80) and young women (VFI: 1.90-2.58; PBF:1.70-2.29). Moreover, based on Youden's index, VFI and PBF exhibited the superiority for identifying prehypertension in men (0.20-0.32) and women (0.31-0.39), respectively.

CONCLUSION

In summary, there was stronger association of VFI and PBF with prehypertension in men than in women, respectively, especially for young adults.

Independent association of resting energy expenditure with blood pressure: confirmation in populations of the African diaspora

BACKGROUND

Obesity is a major risk factor for hypertension, however, the physiologic mechanisms linking increased adiposity to elevations in blood pressure are not well described. An increase in resting energy expenditure (REE) is an obligatory consequence of obesity. Previous survey research has demonstrated that REE is an independent predictor of blood pressure, and eliminates the co-linear association of body mass index. This observation has received little attention and there have been no attempts to provide a causal explanation.

METHODS

At baseline in an international comparative study on obesity, 289 participants aged 25-44 were recruited from communities in the US, the Seychelles, Ghana and South Africa and had REE measured with indirect calorimetry. All participants were thought to be free of major illness.

RESULTS

In multivariate regression models, both systolic and diastolic blood pressure were positively associated with REE (p < 0.01), while body mass index and fat mass were negatively correlated with systolic blood pressure (p < 0.01, and p < 0.05 respectively), but not diastolic blood pressure.

CONCLUSIONS

These data confirm previous reports and suggest that a common physiologic abnormality links REE and blood pressure. Elevated catecholamines, a putative metabolic characteristic of obesity, is a possible candidate to explain this association. The direct role of excess adipose tissue is open to question.

The Role of the Autonomic Nervous System in the Pathophysiology of Obesity

Obesity is reaching epidemic proportions globally and represents a major cause of comorbidities, mostly related to cardiovascular disease. The autonomic nervous system (ANS) dysfunction has a two-way relationship with obesity. Indeed, alterations of the ANS might be involved in the pathogenesis of obesity, acting on different pathways. On the other hand, the excess weight induces ANS dysfunction, which may be involved in the haemodynamic and metabolic alterations that increase the cardiovascular risk of obese individuals, i.e., hypertension, insulin resistance and dyslipidemia. This article will review current evidence about the role of the ANS in short-term and long-term regulation of energy homeostasis. Furthermore, an increased sympathetic activity has been demonstrated in obese patients, particularly in the muscle vasculature and in the kidneys, possibily contributing to increased cardiovascular risk. Selective leptin resistance, obstructive sleep apnea syndrome, hyperinsulinemia and low ghrelin levels are possible mechanisms underlying sympathetic activation in obesity. Weight loss is able to reverse metabolic and autonomic alterations associated with obesity. Given the crucial role of autonomic dysfunction in the pathophysiology of obesity and its cardiovascular complications, vagal nerve modulation and sympathetic inhibition may serve as therapeutic targets in this condition.

The associations of resting metabolic rate with chronic conditions and weight loss

The aim of this study was to examine the associations between baseline and changes in resting metabolic rate (RMR) with chronic condition(s) and weight loss (WL). Sex stratified analysis was undertaken on 393 adults from the Wharton Weight Management Clinics. The association between baseline RMR and WL was examined adjusting for age, BMI, ethnicity and treatment time. The association between changes in RMR (ΔRMR) and WL was also examined adjusting for baseline RMR and above covariates. Models were further adjusted for high glucose, triglycerides, blood pressure, low-density lipoprotein (LDL) and low high-density lipoprotein (HDL). While men (6.0 ± 8.6 kg) and women (5.6 ± 8.3 kg) had significant WL throughout the intervention, their measured decreases in RMR (-48 ± 322 kcal and -5 ± 322 kcal, respectively) were non-significant (P > 0.05). Individuals with a high blood pressure had a higher baseline RMR and women with a high LDL had a lower baseline RMR than those without the chronic condition (P < 0.05). Regardless of sex, WL was not significantly associated with baseline RMR or ΔRMR (P > 0.05) in both models. Participants with a low baseline RMR do not appear to be at a disadvantage for WL. Further, WL can occur without decreases in RMR in populations with high levels of obesity and obesity-related comorbidities.

Metabolic risk factors in mice divergently selected for BMR fed high fat and high carb diets

Factors affecting contribution of spontaneous physical activity (SPA; activity associated with everyday tasks) to energy balance of humans are not well understood, as it is not clear whether low activity is related to dietary habits, precedes obesity or is a result of thereof. In particular, human studies on SPA and basal metabolic rates (BMR, accounting for >50% of human energy budget) and their associations with diet composition, metabolic thrift and obesity are equivocal. To clarify these ambiguities we used a unique animal model-mice selected for divergent BMR rates (the H-BMR and L-BMR line type) presenting a 50% between-line type difference in the primary selected trait. Males of each line type were divided into three groups and fed either a high fat, high carb or a control diet. They then spent 4 months in individual cages under conditions emulating human "sedentary lifestyle", with SPA followed every month and measurements of metabolic risk indicators (body fat mass %, blood lipid profile, fasting blood glucose levels and oxidative damage in the livers, kidneys and hearts) taken at the end of study. Mice with genetically determined high BMR assimilated more energy and had higher SPA irrespective of type of diet. H-BMR individuals were characterized by lower dry body fat mass %, better lipid profile and lower fasting blood glucose levels, but higher oxidative damage in the livers and hearts. Genetically determined high BMR may be a protective factor against diet-induced obesity and most of the metabolic syndrome indicators. Elevated spontaneous activity is correlated with high BMR, and constitutes an important factor affecting individual capability to sustain energy balance even under energy dense diets.

Leptin-Induced Endothelium-Independent Vasoconstriction in Thoracic Aorta and Pulmonary Artery of Spontaneously Hypertensive Rats: Role of Calcium Channels and Stores

Decreased leptin-induced endothelium-dependent vasodilation has been reported in spontaneously hypertensive rats (SHR). Here, we report leptin-induced vasoconstriction in endothelium-denuded pulmonary artery and thoracic aorta from SHR and sought to characterize calcium handling underlying these mechanisms. Vasoreactivity to leptin was evaluated on pulmonary artery and thoracic aorta rings from 18 weeks old male SHR with or without calcium free medium, caffeine + thapsigargin + carbonyl cyanide-4-trifluoromethoxyphenylhydrazone emptying intracellular calcium stores, nifedipine a voltage-gated calcium channel inhibitor, SKF-96365 a transient receptor potential cation channels (TRPC) inhibitor, wortmaninn, a phosphatidylinositide 3-kinases (PI3K) inhibitor, or PD98059 a mitogen-activated protein kinase kinase (MAPKK) inhibitor. Calcium imaging was performed on cultured vascular smooth muscle cells incubated with leptin in presence or not of wortmaninn or PD98059. Leptin induced vasoconstriction in denuded pulmonary artery and thoracic aorta from SHR. Response was abolished when intra- or extracellular calcium stores were emptied, after blocking TRPC or voltage-dependent calcium channels or when using MAPKK or PI3K inhibitors. In vascular smooth muscle cells, leptin increased intracellular calcium. This rise was higher in SHR and abolished by MAPKK or PI3K inhibitors. TRPC6 gene expression was upregulated in arteries from SHR. Leptin-induced vasoconstriction in denuded arteries of SHR requires intracellular stores and is TRPC- and voltage-gated calcium channels dependent. Intracellular calcium increase is more pronounced in spontaneously hypertensive rats.

Common Medications Which Lead to Unintended Alterations in Weight Gain or Organ Lipotoxicity

Obesity is one of the most common chronic conditions in the world. Its management is difficult, partly due to the multiple associated comorbidities including fatty liver, diabetes, hypertension, and hyperlipidemia. As a result, the choice of prescription medications in overweight and obese patients has important implications as some of them can actually worsen the fat accumulation and its associated metabolic complications. Several prescription medications are associated with weight gain with mechanisms that are often poorly understood and under-recognized. Even less data are available on the distribution of fat and lipotoxicity (the organ damage related to fat accumulation). The present review will discuss the drugs associated with weight gain, their mechanism of action, and the magnitude and timing of their effect.

An explorative study of metabolic responses to mental stress and yoga practices in yoga practitioners, non-yoga practitioners and individuals with metabolic syndrome

BACKGROUND

Stress places a metabolic burden on homeostasis and is linked to heightened sympathetic activity, increased energy expenditure and pathology. The yogic state is a hypometabolic state that corresponds with mind-body coherence and reduced stress. This study aimed to investigate metabolic responses to stress and different yoga practices in regular yoga practitioners (YP), non-yoga practitioners (NY) and metabolic syndrome patients (MS).

METHODS

YP (n = 16), NY (n = 15) and MS (n = 15) subjects underwent an experimental protocol that comprised of different 5-minute interventions including mental arithmetic stress test (MAST), alternate nostril breathing (ANB), Kapabhati breathing (KB) and meditation (Med) interspersed with 5 minutes of quiet resting (neutral condition (NC)). During the intervention periods continuous body weight adjusted oxygen consumption (VO2ml/min/kg) was measured using open circuit indirect calorimetry with a canopy hood.

RESULTS

This is the first study to report oxygen consumption (OC) in yoga practitioners during and after MAST and the first to report both within and between different populations. The results were analysed with SPSS 16 using 3X9 mixed factorial ANOVAs. The single between-subject factor was group (YP, NY and MS), the single within-subject factor was made up of the nine intervention phases (NC1, MAST, NC2, ANB, NC3, KB, NC4, Med, NC5). The results demonstrated that the regular YP group had significantly less OC and greater variability in their OC across all phases compared to the MS group (p = .003) and NY group (p = .01). All groups significantly raised their OC during the mental arithmetic stress, however the MS group had a significantly blunted post-stress recovery whereas the YP group rapidly recovered back to baseline levels with post stress recovery being greater than either the NY group or MS group.

CONCLUSIONS

Yoga practitioners have greater metabolic variability compared to non-yoga practitioners and metabolic syndrome patients with reduced oxygen requirements during resting conditions and more rapid post-stress recovery. OC in metabolic syndrome patients displays significantly blunted post-stress recovery demonstrating reduced metabolic resilience. Our results support the findings of previous randomised trials that suggest regular yoga practice may mitigate against the effects of metabolic syndrome.

CLINICAL TRIAL NUMBER

ACTRN12614001075673; Date of Registration: 07/10/2014.

Resting energy expenditure and systolic blood pressure relationships in women across 4.5 years

Recent studies have reported a strong association between blood pressure (BP) and resting energy expenditure (REE). However, it is not known whether this relationship persists over time. Therefore, the authors examined the temporal relationship between REE and systolic BP. In addition, the impact of sympathetic tone and anthropometric variables on this relationship was examined. All testing was performed on healthy, overweight African American and European American women aged 25 to 45 years over 4.5 years in the University of Alabama at Birmingham General Clinical Research Center. Repeated-measures mixed-models revealed REE as a significant determinant of systolic BP (β=0.0155, P<.0001), independent of catecholamines, leg fat, visceral fat, fat-free mass, fat mass, height, relative skeletal muscle index, and resting heart rate. Observations that REE is predictive of systolic BP across 4.5 years support previous findings that REE may potentially mediate resting BP, independent of anthropometric variables and a marker for sympathetic tone.

Frequency, Awareness, Treatment and Control of Hypertension in the over 40 Population of Erzincan

To determine distribution of blood pressure (BP) and prevalence, awareness, treatment and control of hypertension in 5 primary health care centers of Erzincan. A population-based cross-sectional survey was carried out in January - May 2009. A two-stage sampling method was used to select a sample of adult population 40 and over years of age. The total number of participants was 1570. Data were collected by face-to-face interview technique in the primary health care setting. Main outcome measures; mean systolic and diastolic blood pressures, distribution of blood pressure, prevalence of hypertension (mean systolic BP≥140 mmHg or mean diastolic BP ≥90 mmHg, or previously diagnosed and/or taking antihypertensive drugs) awareness, treatment and control of hypertension were assessed. The overall hypertension prevalence was 67.0% in the study sample and 77.4% of them were aware of their hypertension and received a pharmacologic treatment. Of the patients who were aware of the disease, 51.8% use drug treatment. Of the patients who had a drug treatment, 33.9 % were under control in terms of blood pressure. Our data indicate that hypertension is a highly prevalent but inadequately managed health problem in Erzincan. There is an urgent need for population-based strategies to improve prevention, early detection, and control of hypertension.

Best-fitting prediction equations for basal metabolic rate: informing obesity interventions in diverse populations

Basal metabolic rate (BMR) represents the largest component of total energy expenditure and is a major contributor to energy balance. Therefore, accurately estimating BMR is critical for developing rigorous obesity prevention and control strategies. Over the past several decades, numerous BMR formulas have been developed targeted to different population groups. A comprehensive literature search revealed 248 BMR estimation equations developed using diverse ranges of age, gender, race, fat-free mass, fat mass, height, waist-to-hip ratio, body mass index and weight. A subset of 47 studies included enough detail to allow for development of meta-regression equations. Utilizing these studies, meta-equations were developed targeted to 20 specific population groups. This review provides a comprehensive summary of available BMR equations and an estimate of their accuracy. An accompanying online BMR prediction tool (available at http://www.sdl.ise.vt.edu/tutorials.html) was developed to automatically estimate BMR based on the most appropriate equation after user-entry of individual age, race, gender and weight.

Oxygen Consumption Changes With Yoga Practices

Oxygen consumption varies with physical and mental activity as well as pathological conditions. Although there is a strong relationship between yoga and metabolic parameters, the relationship between yoga and oxygen consumption has not yet been formally reviewed. This systematic review attempted to include all studies of yoga that also measured oxygen consumption or metabolic rate as an outcome. A total of 58 studies were located involving between 1 and 104 subjects (average 21). The studies were generally of poor methodological quality and demonstrated great heterogeneity with different experimental designs, yoga practices, time periods, and small sample sizes. Studies report yoga practices to have profound metabolic effects producing both increase and decrease in oxygen consumption, ranging from 383% increase with cobra pose to 40% decrease with meditation. Compared to nonpractitioners, basal oxygen consumption is reported to be up to 15% less in regular yoga practitioners, and regular yoga practice is reported to have a training effect with oxygen consumption during submaximal exercise decreasing by 36% after 3 months. Yoga breathing practices emphasize breathing patterns and retention ratios as well as unilateral nostril breathing, and these factors appear critical in influencing oxygen consumption. A number of studies report extraordinary volitional control over metabolism in advanced yoga practitioners who appear to be able to survive extended periods in airtight pits and to exceed the limits of normal human endurance. More rigorous research with standardized practices is required to determine the mechanisms of yoga’s metabolic effects and the relevance of yoga practices in different clinical populations.

Stronger associations of obesity with prehypertension and hypertension in young women than in young men

OBJECTIVE

Obesity is an important risk factor for prehypertension and hypertension, and there are sex-specific differences in prevalences of obesity and hypertension. The aim of this study was to determine whether sex influences the relationships of obesity with prehypertension and hypertension.

METHODS

The participants were 28,325 Japanese men and women aged 20-39 years. Obesity was evaluated by BMI (≥ 25 kg/m) and waist-to-height ratio (WHtR ≥ 0.5). Associations of obesity with prehypertension and hypertension were compared in men and women by using odds ratio (OR) and area under the curve (AUC).

RESULTS

ORs for prehypertension and hypertension in participants with vs. participants without high BMI or WHtR were significantly higher than a reference level of 1.00 both in men and women and were significantly higher in women than in men. ORs for prehypertension and hypertension of participants with vs. participants without high BMI were 3.10 (2.84-3.38) (men) vs. 5.54 (4.80-6.40) (women) (P < 0.01) and 12.06 (10.83-13.42) (men) vs. 34.58 (26.55-45.04) (women) (P < 0.01), respectively. ORs of the interaction terms consisting of sex (male vs. female) and adiposity (high vs. not high BMI or WHtR) for prehypertension and hypertension were found to be significant. AUCs for the relationships of BMI with prehypertension and hypertension were significantly larger than a reference level of 0.500 and were significantly larger in women than in men.

CONCLUSION

The results suggest that the associations of obesity with prehypertension and hypertension are stronger in women than in men.

Does it matter how blood pressure is lowered in patients with metabolic risk factors?

Abdominal obesity is an important cardiovascular risk factor. It is a primary driver of the metabolic syndrome, the cluster of metabolic risk factors that includes insulin resistance and dyslipidemia, and often occurs in association with hypertension. The aim of antihypertensive therapy in patients with metabolic risk factors is to reduce cardiovascular risk, but some antihypertensive agents can exert adverse metabolic effects. For example, beta-blockers produce significant weight gain, and are associated with an increased incidence of diabetes. By contrast, agents that inhibit the renin-angiotensin system (RAS), such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), have been shown to be associated with a decreased risk of new-onset diabetes. This reflects the finding that increased activation of the RAS in obese individuals can contribute to the development of the metabolic syndrome. The ARB telmisartan has been shown to act as a selective peroxisome proliferator-activated receptor (PPAR)-gamma modulator. It is known that PPAR-gamma plays a role in the regulation of multiple genes affecting carbohydrate and lipid metabolism; however, the clinical significance of this remains to be established. The potential metabolic effects of RAS blockade should be considered in the choice of antihypertensive therapy for patients with metabolic risk factors, including obesity.

Prevalence of Obesity and Associated Risk Factors in a Turkish Population (Trabzon City, Turkey)

OBJECTIVE

To estimate the prevalence of overweight and obesity (general and central) in the Trabzon Region and its associations with demographic factors (age, sex, marital status, reproductive history in women, and level of education), socioeconomic factors (household income and occupation), family history of selected medical conditions (diabetes, hypertension, and obesity), lifestyle factors (smoking habits, physical activity, and alcohol consumption), and hypertension in the adult population.

RESEARCH METHODS AND PROCEDURES

A sample of households was systematically selected from the central province of Trabzon and its five towns, namely, Sürmene, Vakfikebir, Maçka, Hayrat, and Tonya. A total of 5016 subjects (2728 women and 2288 men) were included in the study. Individuals more than 20 years old were selected from their family health cards. Demographic factors, socioeconomic factors, family history of selected medical conditions, and lifestyle factors were obtained for all participants. Systolic blood pressure and diastolic blood pressure levels were measured for all subjects. Study procedures were carried out in the local health centers in each town over an 8-month period. Obesity was defined as BMI > or = 30 kg/m2 and overweight as BMI = 25.0 to 29.9 kg/m2.

RESULTS

The prevalence of obesity was 23.5%: 29.4% in women and 16.5% in men. The combined prevalence of both overweight and obesity was 60.3%. The prevalence of abdominal obesity was 29.4%: 38.9% among women and 18.1% among men. The prevalence of obesity increased with age, being highest in the 60- to 69-year-old age group (40.8%) but lower again in the 70+ age group. Obesity was associated positively with marital status, parity, cessation of cigarette smoking, alcohol consumption, and household income and inversely with level of education, cigarette use, and physical activity. Also, obesity was associated positively with hypertension.

DISCUSSION

In the Trabzon Region, 60.3% of the adult population presents with some excess weight. Obesity is a major public health problem that requires generalized interventions to prevent it among the adult population.

Influence of resting energy expenditure on blood pressure is independent of body mass and a marker of sympathetic tone

Two recent examinations reported a strong association between blood pressure (BP) and resting energy expenditure (REE), independent of body mass and body composition. Both reports postulate that neurohumoral processes that contribute to variation in REE may partly mediate the body mass effect on BP. Therefore, we examined the relationship of REE and BP in 108 asymptomatic women (a) to confirm previous findings in a novel population and (b) to examine the impact of a marker of sympathetic tone on this relationship, as this was indicated as a potentially salient intermediary in previous reports. All testing was performed during a 4-day admission to the General Clinical Research Center. Resting energy expenditure was measured by indirect calorimetry, body composition was determined by dual-energy x-ray absorptiometry, and 24-hour fractionated urinary norepinephrine was determined by high-performance liquid chromatography. Multiple linear regression revealed REE as a significant predictor of systolic BP (β = 0.30, P = .04), independent of race (β = 0. 28, P = .01), age (β = -0.02, P = .80), height (β = -0.38, P = .08), fat mass (β = 0.22, P = .20), fat-free mass (β = 0.08, P = .65), and 24-hour fractionated urinary norepinephrine (β = 0.06, P = .57); and the same model using diastolic BP as the dependent variable approached significance (β = 0.24, P = .09). This study affirms previous findings that REE may be a potential mediator in resting BP, independent of many well-cited factors and, additionally, a marker of sympathetic tone.

Neuro-endocrine regulation of blood pressure

As our understanding of the underlying aetiology of hypertension is far from adequate, over 90% of patients with hypertension receive a diagnosis of essential hypertension. This non-specific diagnosis leads to suboptimal therapeutics and a major problem with non-compliance. Understanding the normal control of blood pressure (BP) is, hence, important for a better understanding of the disease.This review attempts to unravel the present understanding of BP control. The local mechanisms of BP control, the neural mechanisms, renal-endocrine mechanisms, and a variety of other hormones that have a bearing in normal BP control are discussed and the possible role in the pathophysiology is alluded to.

Leptin and the clinical cardiovascular risk

Obesity is a universal health problem of increasing prevalence and represents a major public health concern. Obesity is associated with a high risk of developing cardiovascular and metabolic diseases such as hypertension, coronary atherosclerosis, myocardial hypertrophy, diabetes, dyslipidemia, and increased cardiovascular morbidity and mortality. There has been an ongoing search for mediators between obesity and cardiovascular disease. Leptin is a novel and very promising molecule of research that may link these pathologic conditions. Since its discovery in 1994, major advances have been made in the understanding of neuroendocrine mechanisms regulating appetite, metabolism, adiposity, sympathetic tone and blood pressure. In this review, we discuss the physiological and pathophysiological roles of leptin in the causation of various cardiovascular diseases.

Influences of gender on the interaction between sympathetic nerve traffic and central adiposity

CONTEXT

Sympathetic activation promotes insulin resistance and arterial hypertension with increasing adiposity. A difference in the relationship between adiposity and sympathetic activity between women and men could contribute to the known gender difference in cardiovascular disease risk.

OBJECTIVE

We tested whether muscle sympathetic nerve activity (MSNA) is correlated differently with waist circumference, waist to hip ratio (WHR), and body mass index (BMI) in women and men.

DESIGN AND SETTING

We pooled data from two microneurography centers (Berlin, Germany; Gdansk, Poland) for a cross-sectional study.

PARTICIPANTS

We studied 111 normotensive, healthy Caucasian subjects (70 males and 41 females). Age ranged between 19 and 62 yr and BMI ranged between 18 and 40 kg/m(2).

INTERVENTION

No intervention was applied during the study.

MEASUREMENTS

Supine heart rate, blood pressure, and MSNA were recorded after at least 30 min rest.

RESULTS

MSNA in bursts per minute was age dependent in both sexes [r (male) = 0.56, r (female) = 0.34, P < 0.01]. Controlling for waist and hip circumferences, age dependence remained highly significant in men (r = 0.43) and women (r = 0.43). Adjusting for age, in men, waist circumference (r = 0.29), WHR (r = 0.39), and BMI (r = 0.31) were predictive for MSNA and directly correlated (P < 0.01) but not in women. Adjusting for BMI, in men, only WHR (r = 0.40) remained predictive for MSNA.

CONCLUSION

These data support the hypothesis of a gender difference in the regulation of the sympathetic nervous system, in which MSNA mainly relates to WHR in men but not women. The phenomenon may contribute to the sexual dimorphism in cardiovascular disease risk.

Association of lactate with blood pressure before and after rapid weight loss

BACKGROUND

The mechanism linking obesity with its downstream complications is poorly understood. Accumulating evidence suggests that insufficient oxidative capacity plays a central role in the development of insulin resistance and, perhaps, hypertension.

METHODS

To investigate this hypothesis, we measured lactate, a marker of the gap between energy expenditure and oxidative capacity, in 40 obese subjects with the metabolic syndrome (Ob-MS), 40 obese subjects without the metabolic syndrome (Ob), and 20 lean controls (LCs). The 40 Ob-MS participants were then entered into a 12-20 week very low-calorie diet (VLCD) intervention. The change in lactate and a number of other metabolic factors including blood pressure were subsequently assessed.

RESULTS

At baseline, median lactate levels were significantly higher in both the Ob (36.4 mg/dl) and Ob-MS (34.7 mg/dl) groups when compared to LCs (17.4 mg/dl; P < 0.001). After the VLCD intervention, Ob-MS subjects lost 14.7 kg on average, corresponding to a 5.0 kg/m(2) decrease in body mass index (BMI). Lactate levels fell from 41.3 to 28.7 mg/dl, a 31% reduction (P = 0.006). Even after adjustment for BMI change, change in lactate was strongly associated with change in diastolic blood pressure (DBP) (P = 0.007) and mean arterial pressure (P = 0.014), but not with systolic blood pressure (SBP) (P = 0.20) or other obesity-related traits.

CONCLUSIONS

Baseline and longitudinal associations between lactate and DBP suggest that insufficient oxidative capacity may play a role in obesity-related hypertension.

Prevalence of prehypertension and hypertension and associated risk factors among Turkish adults: Trabzon Hypertension Study

BACKGROUND

To estimate the prevalence, awareness and control of prehypertension (preHT) and hypertension (HT) as defined by JNC-7 criteria in the Trabzon Region and its associations with demographic factors (age, sex, obesity, marital status, reproductive history in women and level of education), socioeconomic factors (household income and occupation), family history of selected medical conditions (diabetes, hypertension, obesity and cardiovascular disease), lifestyle factors (smoking habits, physical activity and alcohol consumption) in the adult population.

METHODS

In this cross-sectional survey, a sample of households was systematically selected from the central province of Trabzon and its nine towns. A total of 4809 adult subjects (2601 women and 2208 men) were included in the study. Demographic and socioeconomic factors, family history of selected medical conditions, and lifestyle factors were obtained for all participants. Systolic blood pressure (BP) and diastolic BP levels were measured for all subjects. The persons included in the questionnaire were invited to the local medical centers for blood examination between 08:00-10:00 following 12 hours of fasting. The levels of serum glucose (FBG), total cholesterol (Total-C), high density cholesterol (HDL-C), low density cholesterol (LDL-C) and triglycerides were measured with autoanalyzer. Definition and classification of HT was performed according to guidelines from the US JNC-7 report. Prevalence, awareness, treatment and control of HT were assessed.

RESULTS

The prevalences of HT and preHT were 44.0% (46.1% in women and 41.6% in men) and 14.5% (12.6% in women and 16.8% in men), respectively. Overall, only 41% of the hypertensive individuals had been previously diagnosed. Furthermore, 54.5% of the hypertensive subjects were being treated with antihypertensive drugs (AHD), but only 24.3% of treated subjects had their BP adequately controlled. Among all hypertensive subjects (known and newly diagnosed), only 5.43% had their BP under control. The prevalence of HT increased with age, being highest in the 60- to 69-year-old age group (84.4%) but lower again in the 70+ age group. Interestingly, the prevalence was 16.9% in the 20-to 29-year old age group. HT was associated positively with marital status, parity, cessation of cigarette smoking, and negatively with level of education, alcohol consumption, current cigarette use, and physical activity. Multinomial logistic regression analysis revealed that HT were significantly associated with age, male gender, BMI, low education level, nonsmoking, positive family history of selected medical conditions, occupation, and parity.

CONCLUSIONS

The Trabzon Hypertension Study data indicated that HT is very common and is an important health problem in the adult population of Trabzon. Patients who are unaware of their status and treated uncontrolled hypertensives are at high risk of early cardiovascular morbidity and mortality. To control preHT and HT, effective public health education and urgent precautions are needed. The precautions include serious health education, a well-balanced diet and increasing physical activity.

Predictors of weight change in overweight patients with myocardial infarction

BACKGROUND

Weight loss is recommended among overweight survivors of myocardial infarction (MI). This study describes patterns of weight change among overweight patients with MI and identifies factors associated with weight change.

METHODS

A prospective cohort of 1253 overweight or heavier (body mass index [BMI] > or = 25 kg/m2) post-MI patients were enrolled in the 19-center PREMIER study and followed up for 1 year to determine changes in weight. Patients were categorized at 1 month as overweight (BMI = 25-29.9 kg/m2), obese (BMI = 30-39.9 kg/m2), or morbidly obese (BMI > or = 40 kg/m2). Unadjusted percent weight change was assessed at 1 year, and multivariable linear regression was used to identify independent correlates of change.

RESULTS

Mean weight change was -0.2% and varied by the severity of baseline obesity (+0.4% for overweight patients, -0.5% for obese patients, and -3.7% for morbidly obese patients [P < .001]). Multivariable analyses revealed the following to be significantly associated with weight change: depression 1 month post-MI (+2.7%, P = .001), lack of health insurance (+2%, P = .01), smoking cessation 1 month post-MI (+2.7% vs current smokers, P < .001), morbid obesity (+4.7% vs overweight patients, P < .0001), and increasing age (-0.8% per decade, P = .001). An interaction between smoking cessation and weight class was detected in that overweight patients who quit had a mean increase of 5.3% (95% CI 3.1%-7.4%), whereas no significant change was observed among obese and morbidly obese patients who quit.

CONCLUSIONS

Although post-MI patients had negligible weight loss over 1 year, several sociodemographic, clinical, and lifestyle characteristics were associated with weight change. New, targeted interventions will likely be needed to improve weight management after an MI.

The sympathetic nervous system and the metabolic syndrome

Studies performed in the past two decades have unequivocally shown that several of the components of the metabolic syndrome are associated with indirect and direct markers of adrenergic overdrive. This is the case for hypertension and obesity, in which resting tachycardia, elevated plasma norepinephrine values, increased sympathetic nerve traffic, as well as augmented levels of total and regional norepinephrine spillover have been reported. This is also the case for insulin resistance, i.e. a metabolic condition frequently complicating the various components of the pathological condition identified as the 'metabolic syndrome'. After briefly describing the epidemiological and the cardiovascular risk profile of the disease, this paper will examine the behaviour of the sympathetic nervous system in the metabolic syndrome as well as the mechanisms potentially responsible for this neurogenic abnormality. This will be followed by an analysis of the role played by neuroadrenergic factors in disease progression as well as in the pathogenesis of its complications. Finally, the therapeutic implications of these findings will be highlighted.

Leptin and hypertension in obesity

Leptin, a peptide discovered more than 10 years ago, decreases food intake and increases sympathetic nerve activity to both thermogenic and non-thermogenic tissue. Leptin was initially believed to be an anti-obesity hormone, owing to its metabolic effects. However, obese individuals, for unknown reasons, become resistant to the satiety and weight-reducing effect of the hormone, but preserve leptin-mediated sympathetic activation to non-thermogenic tissue such as kidney, heart, and adrenal glands. Leptin has been shown to influence nitric oxide production and natriuresis, and along with chronic sympathetic activation, especially to the kidney, it may lead to sodium retention, systemic vasoconstriction, and blood pressure elevation. Consequently, leptin is currently considered to play an important role in the development of hypertension in obesity.

Effect of an aerobic exercise training program on resting metabolic rate in chronically beta-adrenergic blocked hypertensive patients

PURPOSE

There is substantial evidence that the use of beta-adrenergic receptor blockers (beta-blockers) is associated with a reduction in resting metabolic rate (RMR) and that a weight gain usually occurs in the first few months of treatment. The purpose of this study was to determine if RMR of overweight and sedentary subjects consuming beta-blockers can be increased following an aerobic exercise training program.

METHODS

Twenty-four subjects participated in the study; 11 (6 women, 5 men) were treated with beta-blockers for hypertension and 13 (9 women, 4 men) were nonmedicated (control group). Body composition, RMR, and peak oxygen uptake (VO2peak) were assessed for all subjects before and after a 12-week aerobic exercise training program. Weekly exercise energy expenditure equaled 83.68 kJ (20 kcal) per kg of body weight while exercise intensity was maintained between 60% and 70% of the VO2 reserve.

RESULTS

Body composition, RMR, and VO2peak did not differ among groups at the beginning of the study. Body weight (-1.4 kg for beta-blockers, P < .05; -2.5 kg for control, P < .05) and VO2peak (+2.2 mL x kg(-1) x min(-1) for beta-blockers, P < .05; +4.1 mL x kg(-1) x min(-1) for control, P < .001) were significantly improved in both groups, whereas RMR (-272 kJ x day(-1) for beta-blockers, NS; +573 kJ x day(-1) for control, P < .05) was increased only in the control group after the aerobic exercise training program.

CONCLUSIONS

These results suggest that beta-blockers limit the increase in RMR normally observed following an aerobic exercise training program. Consequently, obtaining a negative energy balance in an attempt to lose weight may be more difficult.

Leptin is not associated independently with hypertension in Japanese-Brazilian women

We evaluated the relationship of leptin with hypertension adjusted for body mass index (BMI) and/or waist circumference in a population of Japanese-Brazilian women aged > or = 30 years with centrally distributed adiposity. After excluding diabetic subjects, the study subjects--who participated in a population-based study on the prevalence of metabolic syndrome--showed prevalence rates of obesity (BMI > or = 25 kg/m2) and central adiposity (waist > or = 80 cm) of 32.0 and 37.8%, respectively. The hypertensive group (N = 162) was older, had higher BMI (24.9 +/- 4.2 vs 23.3 +/- 3.4 kg/m2, P < 0.001), waist circumference (81.1 +/- 10.1 vs 76.3 +/- 8.2 cm, P < 0.001) and insulin levels (8.0 +/- 6.2 vs 7.1 +/- 4.9 microU/mL, P < 0.05) than the normotensive group (N = 322) and showed an unfavorable metabolic profile (higher 2-h plasma glucose, C-reactive protein and non-HDL cholesterol levels). Leptin did not differ between groups (8.2 +/- 6.8 vs 7.2 +/- 6.6 ng/mL, P = 0.09, for hypertensive vs normotensive, respectively) and its levels correlated significantly with anthropometric variables but not with blood pressure. Logistic regression analysis indicated that age and waist were independently associated with hypertension but not with homeostasis model assessment of insulin resistance or leptin levels. The lack of an independent association of hypertension with metabolic parameters (2-h glucose, C-reactive protein and non-HDL cholesterol) after adjustment for central adiposity suggested that visceral fat deposition may be the common mediator of the disturbances of the metabolic syndrome. Our data indicate that age and waist are major determinants of hypertension in this population of centrally obese (waist > or = 80 cm) Japanese-Brazilian women, but do not support a role for leptin in the elevation of blood pressure.

A genome scan among Nigerians linking resting energy expenditure to chromosome 16

Energy requirements at rest account for 50% to 75% of total energy expenditure. Interindividual variation in resting energy expenditure (REE) has been studied for potential links to obesity and hypertension. REE is a modestly heritable trait, and yet virtually nothing is known about the genetic factors that might influence the familial patterns. The objectives of this study were to identify the genomic regions showing genetic linkage to REE variation in a Nigerian population. For linkage analysis across the genome, three hundred seventy-seven microsatellite markers were typed on DNA from 995 individuals in 153 families. A genome scan was performed using a multipoint variance component method. Heritability of REE was 0.30 after adjustment for body size. The strongest linkage signal was detected on chromosome 16 (16q22.3) with a likelihood of odds of 2.96 (p = 0.08). Linkage evidence (likelihood of odds > 1) was detected on another three chromosomal regions, namely 2q12.1, 8q21.2, and 15p11.2.

Effect of chronic treatment with beta-blockers on resting energy expenditure in obese hypertensive patients during a low-calorie and physical training program

BACKGROUND AND AIM

To evaluate whether chronic treatment with beta-blockers influences resting energy expenditure (REE) and weight loss after a period of diet and physical activity in obese hypertensive patients.

METHODS AND RESULTS

Seventy-eight obese hypertensive patients (24 males and 54 females) aged 53.7 +/- 11.1 years with mean BMI of 42.4 +/- 5.8 kg/m2 were enrolled. Thirty-eight patients were using beta-blockers while 40 patients who had not received beta-blockers in the past 6 months were the control group. REE was measured with indirect calorimetric method. Total body fat mass, total body fat-free mass (FFM) and total body water (W) were determined by bioelectrical impedance analysis. Patients and controls underwent a structured physical training program and a hypocaloric diet for a period of 31.6 +/- 10.6 days. Measured REE in patients taking beta-blockers was 1818 +/- 309 kcal/24 h and 1853 +/- 348 kcal/24 h in patients not taking beta-blockers; p = non significant. Weight and BMI loss were similar between the two groups and were respectively -6.43 +/- 2.62 kg and -2.42 +/- 0.91 kg/m2 in the beta-blocker group and -7.49 +/- 3.10 kg, -2.78 +/- 1.03 kg/m2 in the non beta-blocker group. Body composition was similar in the two groups. In the comparison between patients treated with selective beta 1-adrenoceptors blockers and non selective beta-blockers we found a significant difference in REE (1704 +/- 283 vs 1974 +/- 278; p = 0.012) and in weight loss (-5.6 +/- 2.4 vs -7.5 +/- 2.7; p = 0.048) at the end of study.

CONCLUSIONS

Beta-blockers are not associated with a lower REE in obese subjects compared to other antihypertensive treatment. Use of non selective beta-adrenergic blockers is associated with a higher REE and weight loss compared to use of selective beta 1-adrenergic blockers. Non selective beta-blockers could be indicated among first choice drugs in hypertensive severely obese subjects without contraindications to beta-blockade.

Effect of selective and nonselective beta-blockers on resting energy production rate and total body substrate utilization in chronic heart failure

BACKGROUND

In chronic heart failure (CHF) beta-blockers reduce myocardial oxygen consumption and improve myocardial efficiency by shifting myocardial substrate utilization from increased free fatty acid oxidation to increased glucose oxidation. The effect of selective and nonselective beta-blockers on total body resting energy production rate (EPR) and substrate utilization is not known.

METHODS

Twenty-six noncachectic patients with moderately severe heart failure (New York Heart Association class II or III, left ventricular ejection fraction < 0.40) were treated with carvedilol (37.5 +/- 13.5 mg/12 h) or bisoprolol (5.4 +/- 3.0 mg/d) for 6 months. Indirect calorimetry was performed before and after 6 months of treatment.

RESULTS

Resting EPR was decreased in carvedilol (5.021 +/- 0.803 to 4.552 +/- 0.615 kJ/min, P <.001) and bisoprolol group (5.230 +/- 0.828 to 4.978 +/- 0.640 kJ/min, P <.05; nonsignificant difference between groups). Lipid oxidation rate decreased in carvedilol and remained unchanged in bisoprolol group (2.4 +/- 1.4 to 1.5 +/- 0.9 mg m(2)/kg min versus 2.7 +/- 1.1 to 2.5 +/- 1.1 mg m(2)/kg min, P <.05). Glucose oxidation rate was increased only in carvedilol (2.6 +/- 1.4 to 4.4 +/- 1.6 mg m(2)/kg min, P <.05), but did not change in bisoprolol group.

CONCLUSIONS

Both selective and nonselective beta-blockers reduce total body resting EPR in noncachectic CHF patients. Carvedilol compared to bisoprolol shifts total body substrate utilization from lipid to glucose oxidation.

Habitual fat intake and basal fat oxidation in obese and non-obese Caucasians

OBJECTIVE

To examine the relationship between habitual fat intake and basal fat oxidation in obese and non-obese Caucasian men and women.

METHODS

Habitual fat intake was assessed by 7-day weighed dietary records and resting fat oxidation was determined after an overnight fast in 132 weight stable non-diabetic subjects (38 males, 94 females). All subjects were characterized for weight, height, waist-to-hip ratio, physical activity, plasma glucose and insulin response to an oral glucose load, plasma catecholamine and leptin levels. Under-reporters, defined according to plausibility of the relationship between energy expenditure and energy intake, were excluded from the analyses.

RESULTS

The mean age was 53.1+/-10.6 y (19-72 y) and mean body mass index (BMI) was 30.7+/-5.8 kg/m(2) (19.4-45.8 kg/m(2)). Sixty-eight subjects were obese (BMI>30 kg/m(2)). Univariate regression analysis revealed a significant, albeit modest, relationship between absolute fat intake and BMI (r(2)=0.06; P<or=0.05) but not between fat intake and fat mass (r(2)=0.026; P=0.08). However, multiple regression analysis revealed significant effects of body fat mass (FM) and sex on basal fat oxidation (bFO) explaining 33% of the variation of bFO (P<or=0.0001; radical s.e.=18.0 g/24 h). In univariate regression analysis, habitual fat intake was significantly related to adjusted fat oxidation, explaining 12% of the variation (P<or=0.0001; radical s.e.=11.7 g/24 h).

CONCLUSION

Habitual fat intake has a significant, albeit modest, effect on basal fat oxidation, even when adjusted for sex and body FM. The rather modest effect of habitual fat intake on fat oxidation may in part explain the increased propensity to gain FM on a high-fat diet.

Use of beta-blockers in obesity hypertension: potential role of weight gain

Beta-blockers are the most frequently used drugs for the treatment of hypertension. Apart from concerns regarding potential adverse metabolic effects on lipids or insulin sensitivity, beta-blockers can also cause weight gain in some patients. This fact appears little known to clinical practitioners and trialists. Thus, only a minority of clinical trials with beta-blockers report weight changes during treatment. In trials that do report weight changes, beta-blockers are associated with a weight gain of 1.2 (range -0.4-3.5) kg. This may be attributable to the fact that beta blockade can decrease metabolic rate by 10%. Beta-blockers may also have other negative effects on energy metabolism. Obesity management in overweight hypertensive patients may therefore be more difficult in the presence of beta-blocker treatment. We therefore question the use of beta-blockers as first-line therapy for overweight or obese patients with uncomplicated hypertension.

New developments in mechanisms of obesity-induced hypertension: role of adipose tissue

Hypertension develops in almost 60% of obese individuals. Apart from the recent observation of obesity-associated structural changes in kidney structure that may lead to enhanced tubular sodium reabsorbtion, reports of paracrine and hormonal factors derived from adipose tissue have prompted speculations about the role of adipose tissue in the pathophysiology of obesity-induced hypertension. We summarize recent data on leptin's sympathoexcitatory actions, the possible influence of adipose tissue on atrial natriuretic peptide levels, and the formation of vasoactive substances, such as angiotensin II and nonesterified fatty acids, by adipocytes. The mechanisms discussed herein may contribute to the typical findings in obesity-induced hypertension, including volume expansion, sodium retention, enhanced sympathetic nervous system activity, increased activity of the systemic renin-angiotensin system, low atrial natriuretic peptide levels, and disturbed glucose and insulin metabolism. Together, these data strengthen the hypothesis that adipose tissue is potentially a major regulator of cardiovascular-renal function.