Obesity-hypertension: emerging concepts in pathophysiology and treatment

Cardiac, Metabolic and Molecular Profiles of Sedentary Rats in the Initial Moment of Obesity

BACKGROUND

Different types of high-fat and/or high-energy diets have been used to induce obesity in rodents. However, few studies have reported on the effects observed at the initial stage of obesity induced by high-fat feeding on cardiac functional and structural remodelling.

OBJECTIVE

To characterize the initial moment of obesity and investigate both metabolic and cardiac parameters. In addition, the role of Ca2+ handling in short-term exposure to obesity was verified.

METHODS

Thirty-day-old male Wistar rats were randomized into two groups (n = 19 each): control (C; standard diet) and high-fat diet (HF, unsaturated high-fat diet). The initial moment of obesity was defined by weekly measurement of body weight (BW) complemented by adiposity index (AI). Cardiac remodelling was assessed by morphological, histological, echocardiographic and papillary muscle analysis. Ca2+ handling proteins were determined by Western Blot.

RESULTS

The initial moment of obesity occurred at the 3rd week. Compared with C rats, the HF rats had higher final BW (4%), body fat (20%), AI (14.5%), insulin levels (39.7%), leptin (62.4%) and low-density lipoprotein cholesterol (15.5%) but did not exhibit alterations in systolic blood pressure. Echocardiographic evaluation did not show alterations in cardiac parameters. In the HF group, muscles were observed to increase their +dT/dt (C: 52.6 ± 9.0 g/mm2/s and HF: 68.0 ± 17.0 g/mm2/s; p < 0.05). In addition, there was no changes in the cardiac expression of Ca2+ handling proteins.

CONCLUSION

The initial moment of obesity promotes alterations to hormonal and lipid profiles without cardiac damage or changes in Ca2+ handling.

Increased Risk of Acute Coronary Syndrome in Patients With Chronic Pancreatitis: A Nationwide Cohort Analysis

Chronic inflammation may promote development of coronary heart disease. Studies on the relationship between chronic pancreatitis (CP) and cardiovascular diseases are scant.We conducted a nationwide retrospective cohort study to determine the risk of acute coronary syndrome (ACS) in patients with CP.We randomly selected a comparison cohort of individuals without CP from the Taiwan National Health Insurance Research Database (N = 23.74 million) and frequency-matched them with patients with CP from 2000 to 2010 in a 1:4 ratio according to age, sex, and index year. The follow-up period lasted from the index date of the new CP diagnosis to the date of ACS diagnosis, censoring, or the end of 2011. We analyzed the risk of ACS by using Cox proportional-hazard models.In total, 17,405 patients with CP and 69,620 individuals without CP were followed for 84,430 and 417,426 person-years. Most patients with CP were men, and the mean age of the patients was 48.3 ± 15.0 years. The overall ACS incidence was 2.15-fold higher in the CP cohort than in the non-CP cohort (4.89 vs 2.28 per 10,000 person-years) with an adjusted hazard ratio (aHR) of 1.40 (95% confidence interval [CI] 1.20-1.64). Compared with individuals without CP, patients with CP aged ≤39 years exhibited the highest risk of ACS (aHR 2.14, 95% CI 1.13-4.02), followed by those aged 40 to 54 years (aHR 1.66, 95% CI 1.23-2.24) and those aged 55 to 69 years (aHR 1.53, 95% CI 1.15-2.03).CP may become an independent risk factor for ACS.

Cardiovascular, cortisol and coping responses in urban Africans: the SAPBA study

Objectives

To assess the relationships between progression of target-organ damage and cardiovascular, cortisol and coping responses in black urban Africans.

Methods

Urban black African gender groups (n = 200) aged 21–62 years from the Sympathetic Activity and Ambulatory Blood Pressure in Africans study were stratified into normotensive and hypertensive groups. Resting and reactivity Finometer blood pressure, fasting sodium fluoride glucose and salivary cortisol values were obtained before and after applying the Stroop and cold pressor tests. Coping strategies were determined and high-resolution ultrasound carotid intima–media scans were done to determine progression of target-organ damage.

Results

A trend of high-normal resting cortisol values during sampling time 1 was demonstrated in all hypertensive men. Both hypertensive gender groups showed increased vascular responses during both mental stressors. During the cold pressor test, vascular responses predicted sub-clinical atherosclerosis in all hypertensive men, independent of sampling time.

Conclusion

Early morning vascular responses in all the hypertensive men could have occurred secondarily to the permissive effect of cortisol on norepinephrine secretion, with subsequent α-adrenergic vasoconstriction. Their α-adrenergic vascular responses during the cold pressor test, however, predicted sub-clinical atherosclerosis, independent of sampling time and cortisol level.

Determinants of the components of arterial pressure among older adults--the role of anthropometric and clinical factors: a multi-continent study

OBJECTIVE

The aim of this study was to evaluate the factors associated with different components of arterial blood pressure in nine nationally-representative samples of people aged ≥50 years.

METHODS

Data were available for 53,289 people aged ≥18 years who participated in the SAGE (WHO Study on global AGEing and adult health) study conducted in China, Ghana, India, Mexico, Russia, and South Africa, and the COURAGE (Collaborative Research on Ageing in Europe) study conducted in Finland, Poland, and Spain, between 2007 and 2012. Standard procedures were used to obtain diastolic and systolic blood pressure (DBP, SBP) measurements to identify hypertensive participants, and to determine mean arterial blood pressure (MAP) and pulse pressure (PP).

RESULTS

The analytical sample consisted of 42,116 people aged 50 years or older. South Africa had the highest prevalence of hypertension (78.3%), and the highest measurements of MAP ± SD (113.6 ± 36.4 mmHg), SBP ± SD (146.4 ± 49.5 mmHg), and DBP ± SD (97.2 ± 33.9 mmHg). In the adjusted models, dose-dependent positive associations between Body Mass Index (BMI) and MAP or PP were observed in most countries (p < 0.05). Diabetes was positively associated with PP in most countries but the association between diabetes and MAP was less consistent. Stroke was associated with both higher MAP and PP in China, Ghana, and South Africa (p < 0.05).

CONCLUSIONS

Obesity and diabetes remain important modifiable risk factors for arterial peripheral resistance and stiffness as reflected by MAP and PP respectively. Controlling arterial pressure abnormalities after stroke events may be important for secondary prevention, particularly in developing countries.

Factors associated with components of arterial pressure among older individuals (the multinational MEDIS study): the role of the Mediterranean diet and alcohol consumption

The aim of this work was to evaluate factors associated with arterial blood pressure in a sample of older Mediterranean people without known cardiovascular disease. During 2005 to 2011, 2813 older (aged 65-100 years) individuals from 22 Mediterranean islands and the rural Mani region (Peloponnesus) voluntarily enrolled. Standard procedures were used to determine arterial BP and pulse pressure and for the evaluation of dietary habits (including tea and alcoholic beverages consumption), lifestyle, and anthropometric and clinical characteristics of the participants. Participants who reported low alcohol consumption (ie, 0-1 glasses per day) were less likely to have hypertension (odds ratio, 0.34; 95% confidence interval, 0.14-0.84) as compared with those who reported high alcohol consumption (ie, 5+ glasses per day). Adherence to the Mediterranean diet was inversely associated with mean arterial pressure (β coefficient, -0.18; 95% confidence interval, -0.33 to -0.16). Alcohol drinking remains an important modifiable risk factor for hypertension. Adherence to the Mediterranean diet was associated with decreased arterial peripheral resistance.

Advances in understanding the interrelations between leptin resistance and obesity

Obesity, which has developed into a global epidemic, is a risk factor in most chronic diseases and some forms of malignancy. The discovery of leptin in 1994 has opened a new field in obesity research. Currently, we know that leptin is the primary signal from energy stores and exerts negative feedback effects on energy intake. However, most individuals with diet-induced obesity (DIO) develop leptin resistance, which is characterized by elevated circulating leptin levels and decreased leptin sensitivity. To date, though various mechanisms have been proposed to explain leptin resistance, the exact mechanisms of leptin resistance in obesity are poorly understood. Consequently, it's an important issue worth discussing regarding what the exact interrelations between leptin resistance and obesity are. Here, we review the latest advancements in the molecular mechanisms of leptin resistance and the exact interrelations between leptin resistance, obesity, and obesity-related diseases, in order to supply new ideas for the study of obesity.

Catheter-based arterial sympathectomy: hypertension and beyond

Transluminal ablation of renal artery sympathetic nerves has been shown to provide a significant and durable reduction in blood pressure with very low complication rates. Additional publications have documented improvement in insulin sensitivity, obstructive sleep apnea indices, and frequency and severity of congestive heart failure in subgroups undergoing the procedure. This technology may provide effective management of other diseases in which there is autonomic imbalance. Available data are reviewed with the intent to provoke interest within the interventional radiology community in this novel technology, which may allow minimally invasive treatment of many important chronic medical conditions.

Blood pressure variability, prehypertension, and hypertension in adolescents

Medical conditions diagnosed during adolescence may have long term impacts on the health of an individual. As a result, identifying cardiovascular risk factors earlier in life such as prehypertension (pre-HTN) and hypertension (HTN) can have significant benefits across an individual’s lifespan. Diagnosing elevated blood pressure (BP) during adolescence can be difficult, partially due to the natural variability that occurs during this period of life. Levels of BP that define adolescent prehypertension/hypertension are provided as well as an abridged review of BP variability across research groups. Strategies for BP management of adolescents are considered, with the primary focus on nonpharmacologic interventions.

Involvement of L-type calcium channel and SERCA2a in myocardial dysfunction induced by obesity

Obesity has been shown to impair myocardial performance. Nevertheless, the mechanisms underlying the participation of calcium (Ca(2+) ) handling on cardiac dysfunction in obesity models remain unknown. L-type Ca(2+) channels and sarcoplasmic reticulum (SR) Ca(2+) -ATPase (SERCA2a), may contribute to the cardiac dysfunction induced by obesity. The purpose of this study was to investigate whether myocardial dysfunction in obese rats is related to decreased activity and/or expression of L-type Ca(2+) channels and SERCA2a. Male 30-day-old Wistar rats were fed standard (C) and alternately four palatable high-fat diets (Ob) for 15 weeks. Obesity was determined by adiposity index and comorbidities were evaluated. Myocardial function was evaluated in isolated left ventricle papillary muscles under basal conditions and after inotropic and lusitropic maneuvers. L-type Ca(2+) channels and SERCA2a activity were determined using specific blockers, while changes in the amount of channels were evaluated by Western blot analysis. Phospholamban (PLB) protein expression and the SERCA2a/PLB ratio were also determined. Compared with C rats, the Ob rats had increased body fat, adiposity index and several comorbidities. The Ob muscles developed similar baseline data, but myocardial responsiveness to post-rest contraction stimulus and increased extracellular Ca(2+) was compromised. The diltiazem promoted higher inhibition on developed tension in obese rats. In addition, there were no changes in the L-type Ca(2+) channel protein content and SERCA2a behavior (activity and expression). In conclusion, the myocardial dysfunction caused by obesity is related to L-type Ca(2+) channel activity impairment without significant changes in SERCA2a expression and function as well as L-type Ca(2+) protein levels.

Role of adipokines in obesity-associated hypertension

It has been well documented that obesity is a major risk factor for the development of the hypertensive state. The correlation between body mass index and blood pressure level is well established. Nevertheless, the exact mechanisms which contribute to obesity-related hypertension remain poorly understood. In the last years, we have realized that the white adipose tissue is not just an inert organ for nutrient storage and isolation but rather depending on the body mass index the biggest endocrinological organ. Thus, the possible contribution of adipokines to the blood pressure elevation becomes an attractive hypothesis to explain the hypertensive state that often occurs in obesity. In this review, we consider direct and indirect effects of main adipokines on structural and functional changes in the cardiovascular system.

Bioinformatic identification and characterization of human endothelial cell-restricted genes

Background

In this study, we used a systematic bioinformatics analysis approach to elucidate genes that exhibit an endothelial cell (EC) restricted expression pattern, and began to define their regulation, tissue distribution, and potential biological role.

Results

Using a high throughput microarray platform, a primary set of 1,191 transcripts that are enriched in different primary ECs compared to non-ECs was identified (LCB >3, FDR <2%). Further refinement of this initial subset of transcripts, using published data, yielded 152 transcripts (representing 109 genes) with different degrees of EC-specificity. Several interesting patterns emerged among these genes: some were expressed in all ECs and several were restricted to microvascular ECs. Pathway analysis and gene ontology demonstrated that several of the identified genes are known to be involved in vasculature development, angiogenesis, and endothelial function (P < 0.01). These genes are enriched in cardiovascular diseases, hemorrhage and ischemia gene sets (P < 0.001). Most of the identified genes are ubiquitously expressed in many different tissues. Analysis of the proximal promoter revealed the enrichment of conserved binding sites for 26 different transcription factors and analysis of the untranslated regions suggests that a subset of the EC-restricted genes are targets of 15 microRNAs. While many of the identified genes are known for their regulatory role in ECs, we have also identified several novel EC-restricted genes, the function of which have yet to be fully defined.

Conclusion

The study provides an initial catalogue of EC-restricted genes most of which are ubiquitously expressed in different endothelial cells.

Leptina, hipertensão arterial e obesidade: importância das ações de enfermagem

O objetivo desta revisão sistemática foi o levantamento de tópicos de relevância sobre as implicações da leptina na modulação da pressão arterial e na gênese, prevenção e tratamento da hipertensão arterial associada à obesidade. Considerando o hormônio como um elo comum entre as duas condições patológicas, foram identificadas as ações para a redução da leptinemia, propostas e discutidas na literatura. Constatou-se que a enfermagem carece de produção de conhecimento que subsidie a assistência ao hipertenso obeso com alterações nos níveis séricos de leptina. Foram descritos os sinais e sintomas multifatoriais que se interrelacionam de maneira dinâmica e paradoxal na manifestação do quadro clínico estudado, com ordenação de intervenções eficazes no cuidado a esses clientes.

Regulation of lipid metabolism by energy availability: a role for the central nervous system

The central nervous system (CNS) is crucial in the regulation of energy homeostasis. Many neuroanatomical studies have shown that the white adipose tissue (WAT) is innervated by the sympathetic nervous system, which plays a critical role in adipocyte lipid metabolism. Therefore, there are currently numerous reports indicating that signals from the CNS control the amount of fat by modulating the storage or oxidation of fatty acids. Importantly, some CNS pathways regulate adipocyte metabolism independently of food intake, suggesting that some signals possess alternative mechanisms to regulate energy homeostasis. In this review, we mainly focus on how neuronal circuits within the hypothalamus, such as leptin- ghrelin-and resistin-responsive neurons, as well as melanocortins, neuropeptide Y, and the cannabinoid system exert their actions on lipid metabolism in peripheral tissues such as WAT, liver or muscle. Dissecting the complicated interactions between peripheral signals and neuronal circuits regulating lipid metabolism might open new avenues for the development of new therapies preventing and treating obesity and its associated cardiometabolic sequelae.

Left ventricular geometry in children and adolescents with primary hypertension

BACKGROUND

Children with hypertension (HTN) are at increased risk for left ventricular hypertrophy (LVH). Increased left ventricular (LV) mass (LVM) by the process of remodeling in response to volume or pressure loading may be eccentric (increased LV diameter) or concentric (increased wall thickness). Our objective was to classify LV geometry among children with primary HTN and examine differences in ambulatory blood pressure (ABP).

METHODS

Subjects aged 7-18 years with suspected HTN were enrolled in this cross-sectional study. ABP and LVM index (LVMI) were measured within the same 24-h period. LV geometry was classified as normal, concentric remodeling, concentric LVH, or eccentric LVH.

RESULTS

Children with LVH had significantly higher ambulatory systolic BP (SBP) and diastolic blood pressure (BP) (DBP) levels and body mass index (BMI) Z-score. Sixty-eight children had HTN based upon ABP monitoring (ABPM). Thirty-eight percent of the hypertensive subjects had LVH, with equal distribution in the concentric and eccentric groups. There were significant differences in the 24-h DBP parameters when the eccentric LVH group was compared to the normal geometry and concentric LVH groups. Relative wall thickness (RWT) was inversely associated with night time DBP parameters. These relationships persisted after controlling for BMI Z-score.

CONCLUSIONS

Although the risk for LVH is associated with increased SBP and BMI Z-score, those with eccentric LVH had significantly higher DBP.

Alcohol consumption is associated with decreased insulin resistance independent of body mass index in Japanese community-dwelling men

Alcohol consumption is associated with a decreased risk of type II diabetes and cardiovascular diseases. However, there is a great deal of controversy concerning the relationship between alcohol consumption and insulin resistance. This association may be further confounded by an increase in body weight levels. The aim of this study was to determine whether alcohol consumption promotes insulin resistance according to body weight levels in community-dwelling men. Study participants without a clinical history of stroke, transient ischemic attack, myocardial infarction, angina or diabetes were randomly recruited from a single community at the time of their annual health examination (678 men aged 59 +/- 14 years). They were classified into never drinkers, light drinkers [< 1 unit (22.9 g ethanol)/day], moderate drinkers (1-1.9 unit/day), and heavy drinkers (> or = 2 unit/day), and further divided into underweight [body mass index (BMI) < 23 kg/m(2)] or overweight (BMI > or = 23.0 kg/m(2)). Insulin resistance was estimated on the basis of the homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA-IR and potential confounders were compared between the groups. The confounders included age, BMI, smoking status, serum gamma glutamyltransferase, and high molecular-weight adiponectin. In the overall, HOMA-IR is significantly correlated with age, BMI, serum gamma glutamyltransferase, and high molecular-weight adiponectin. After adjustment for potential confounders, mean log HOMA-IR is significantly lower in the heavy drinkers irrespective of BMI categories. In conclusion, alcohol consumption is associated with decreased insulin resistance independent of BMI in Japanese community-dwelling men.

Pediatric approach to hypertension

The prevalence of pediatric hypertension (HTN) has increased over the past several decades, bringing with it increased numbers of children with hypertensive sequelae such as left ventricular hypertrophy as well as greater numbers of hypertensive adults. This growing public health concern calls for vigilant screening, diagnosis, evaluation, and treatment of HTN in children. Although primary HTN has become more common in childhood and adolescence, it still should be considered a diagnosis of exclusion. As such, a diagnostic work-up should be conducted to rule out secondary causes of HTN for any child with a confirmed diagnosis of HTN. Important secondary causes of pediatric HTN include renal parenchymal, renovascular, and endocrine etiologies, and secondary HTN becomes more likely the younger the child is and the more severe the blood pressure elevation is at diagnosis. In addition, several genetic disorders have been identified in which one aberrant gene results in severe HTN, often early in life. All hypertensive children, regardless of the cause of their HTN, should be prescribed therapeutic lifestyle changes, and children with symptomatic, secondary, or severe HTN; HTN resistant to lifestyle changes; or children with evidence of end-organ damage also should be prescribed antihypertensive medications.

Predictors of progression from prehypertension to hypertension in Japanese men

BACKGROUND

This 3-year prospective study in middle-aged Japanese men with prehypertension examined the usefulness of the plasma levels of C-reactive protein (CRP) and the brachial-ankle pulse wave velocity (baPWV) as predictors of the development to hypertension as compared with other previously proposed markers, such as the age, initial blood pressure, heart rate, obesity, smoking, and alcohol intake.

METHODS AND RESULTS

Among 777 men with prehypertension (42 +/- 8 years old), hypertension developed in 58 men during the observation period. Significant elevation of blood pressure during this 3-year follow-up was not observed in some, but not all, subjects. Univariate linear regression analysis demonstrated that baPWV, body mass index (BMI), age, and alcohol intake, but not plasma levels of CRP, heart rate, and smoking, on the first examination were significant variables related to the changes in systolic blood pressure from the first examination to the second examination. Multivariate linear regression analysis confirmed that baPWV and BMI were weak but significant independent variables related to the changes in systolic blood pressure (R(2) = 0.03). The logistic regression analysis demonstrated that baPWV >13.5 m/s (adjusted odds ratio = 3.32 (1.79-6.15)) and BMI >25.0 (adjusted odds ratio = 2.27 (1.25 - 4.13)) were significant predictors of future hypertension independent of blood pressure on the first examination.

CONCLUSION

This 3-year prospective study suggested that the baPWV and BMI, but not plasma CRP levels, are not powerful but significant independent markers to identify middle-aged Japanese men with prehypertension at high risk for hypertension.

[Hypertension in obese children and adolescents]

Obesity, especially upper body fat distribution, has become an increasingly important medical problem in children and adolescents. Outcomes related to childhood obesity include, as in adult population, hypertension, type 2 diabetes mellitus, dyslipidemia, left ventricular hypertrophy, obstructive sleep apnea, orthopedic and socio-psychological problems. Obese children are at approximately 3-fold higher risk for hypertension from non-obese ones. Obesity-hypertension appears to be characterized by a preponderance of isolated systolic hypertension, increased heart rate and blood pressure variability, increased levels of plasma catecholamine and aldosterone, and salt-sensitivity. Lifestyle changes of weight loss, healthier diet and regular physical exercise are effective in obesity-hypertension control, though pharmacological treatment is frequently necessary. Screening for dyslipidemia and impaired glucose tolerance should be performed in paediatric patients with obese hypertension on regular basis, at least once annually or semiannually to discover metabolic syndrome and to prevent its increased cardiovascular risk. Of course, prevention of obesity is the primary goal.

High prevalence of prehypertension is associated with the increased body mass index in community-dwelling Japanese

Hypertension and obesity are likely the most common disease in Japan. It has been reported that subjects with prehypertension (systolic blood pressure [SBP] 120-139 mmHg and/or diastolic blood pressure [DBP] 80-89 mmHg) have also an increased risk of cardiovascular disease; however, only limited data are available on the prevalence of prehypertension and its association with body weight. We performed a cross-sectional study to examine whether the status of body weight was associated with prehypertension. Study participants aged 19 to 90 years [1,207 men aged 60 +/- 15 (mean +/- standard deviation) years and 1,634 women aged 63 +/- 12 years] were randomly recruited for a survey at the community-based annual medical check-up. The prevalence of prehypertension was 27.3% in men and 23.9% in women. The levels of SBP and DBP increased, as body mass index (BMI) increased in both genders. In a multivariate-adjusted model, increasing BMI categories were positively associated with prehypertension. Especially in men, compared to participants with BMI of < 21.0 kg/m(2) (referent), the multivariate-odds ratio (95% CI) of prehypertension was 1.90 (1.17-3.09) in the 21.0-23.4 kg/m(2) group, 2.38 (1.31-4.34) in the 23.5-24.9 kg/m(2) group, and 3.79 (2.03-7.09) in the > or = 25.0 kg/m(2) group. In conclusion, even subjects with mildly increased BMI (21.0-24.9 kg/m(2)) had an increased risk of prehypertension in community-dwelling persons. It is time to pay more attention to excess bodyweight in preventing high blood pressure.

Characterization of ion channels in human preadipocytes

Ion channels participate in regulation of cell proliferation. However, though preadipocyte (the progenitor of fat cell) is a type of highly proliferating cells, ion channel expression and their role in proliferation is not understood in human preadipocytes. The present study was designed to characterize ion channels using whole-cell patch clamp technique, RT-PCR, and Western blotting. It was found that a 4-aminopyridine- (4-AP) sensitive transient outward K(+) current (I(to)) was present in a small population of (32.0%) cells, and an outward "noisy" big conductance Ca(2+)-activated K(+) current (I(KCa)) was present in most (92.7%) preadipocytes. The noisy current was inhibited by the big conductance I(KCa) channel blocker paxilline (1 microM), and enhanced by the Ca(2+) ionophore A23187 (5 microM) and the big conductance I(KCa) channel activator NS1619 (10 microM). RT-PCR and Western blot revealed the molecular identities (i.e., KCa1.1 and Kv4.2) of the functional ionic currents I(KCa) and I(to). Blockade of I(KCa) or I(to) with paxilline or 4-AP reduced preadipocyte proliferation, and similar results were obtained with specific siRNAs targeting to KCa1.1 and Kv4.2. Flow cytometric analysis showed ion channel blockade or knockdown of KCa1.1 or Kv4.2 with specific siRNA increased the cell number of G0/G1 phase. The present study demonstrates for the first time that two types of functional ion channel currents, I(to) and big conductance I(KCa), are present in human preadipocytes and that these two types of ion channels participate in regulating proliferation of human preadipocytes.

Asthma, environmental risk factors, and hypertension among Arab Americans in metro Detroit

Asthma and obesity-related health problems disproportionately impact low-income ethnic minority communities residing in urban areas. Environmental risk factors, particularly those related to housing and indoor air, may impact the development or exacerbation of asthma. There is increasing evidence to suggest a link between obesity-related health problems and asthma. Previous studies have also reported that immigrant status may influence myriad risk factors and health outcomes among immigrant populations. The Arab American Environmental Health Project (AAEHP) was the first study to explore environmental health problems among Arab Americans. This paper examined whether hypertensive status modified the relationship between environmental risk factors and asthma among Arab Americans in metro Detroit. An environmental risk index (ERI) was used to quantify household environmental risk factors associated with asthma. Physician diagnosed hypertension was self-reported, and asthma status was determined using responses to a validated symptoms checklist and self-reported diagnosis by a physician. Hypertension significantly modified the relationship between ERI and asthma in this study population. The positive association between household environmental risk factors and asthma was stronger among participants diagnosed with hypertension. Effect modification of the relationship between environmental risk factors and asthma could have serious implications among high-risk communities. However, further research is needed to elucidate the relationships between hypertension, environmental risk factors, and asthma.

Leptin resistance: a possible interface of inflammation and metabolism in obesity-related cardiovascular disease

Leptin is an adipocyte-derived hormone and cytokine that regulates energy balance through a wide range of functions, including several that are important to cardiovascular health. Increased circulating leptin, a marker of leptin resistance, is common in obesity and independently associated with insulin resistance and cardiovascular disease (CVD) in humans. The mechanisms of leptin resistance include genetic mutation, leptin self-regulation, limited tissue access, and cellular or circulating molecular regulation. Evidence suggests that central leptin resistance causes obesity and that obesity-induced leptin resistance injures numerous peripheral tissues, including liver, pancreas, platelets, vasculature, and myocardium. This metabolic- and inflammatory-mediated injury may result from either resistance to leptin's action in selective tissues, or excess leptin action from adiposity-associated hyperleptinemia. In this sense, the term "leptin resistance" encompasses a complex pathophysiological phenomenon. The leptin axis has functional interactions with elements of metabolism, such as insulin, and inflammation, including mediators of innate immunity, such as interleukin-6. Leptin is even purported to physically interact with C-reactive protein, resulting in leptin resistance, which is particularly intriguing, given C-reactive protein's well-studied relationship to cardiovascular disease. Given that plasma levels of leptin and inflammatory markers are correlated and also predict cardiovascular risk, it is conceivable that part of this risk may be mediated through leptin resistance-related insulin resistance, chronic inflammation, type II diabetes, hypertension, atherothrombosis, and myocardial injury. Leptin resistance and its interactions with metabolic and inflammatory factors, therefore, represent potential novel diagnostic and therapeutic targets in obesity-related cardiovascular disease.

Renal antioxidant enzymes and glutathione redox status in leptin-induced hypertension

Previously, we have demonstrated that leptin increases blood pressure (BP) in the rats through two oxidative stress-dependent mechanisms: stimulation of extracellular signal-regulated kinases (ERK) by H(2)O(2) and scavenging of nitric oxide (NO) by superoxide (O(2-.)). Herein, we examined if renal glutathione system and antioxidant enzymes determine the mechanism of prohypertensive effect of leptin. Leptin administered at 0.5 mg/kg/day for 4 or 8 days increased BP and renal Na(+),K(+)-ATPase activity and reduced fractional sodium excretion; these effects were prevented by NADPH oxidase inhibitor, apocynin. Superoxide scavenger, tempol, abolished the effect of leptin on BP and renal Na(+) pump in rats receiving leptin for 8 days, whereas ERK inhibitor, PD98059, was effective in animals treated with leptin for 4 days. Leptin administered for 4 days decreased glutathione (GSH) and increased glutathione disulfide (GSSG) in the kidney. In animals receiving leptin for 8 days GSH returned to normal level, which was accompanied by up-regulation of gamma-glutamylcysteine synthetase (gamma-GCS), a rate-limiting enzyme of the GSH biosynthetic pathway. In addition, superoxide dismutase (SOD) activity was decreased, whereas glutathione peroxidase (GPx) was increased in rats receiving leptin for 8 days. Cotreatment with gamma-GCS inhibitor, buthionine sulfoximine (BSO), accelerated, whereas GSH precursor, N-acetylcysteine (NAC), attenuated leptin-induced changes in gamma-GCS, SOD, and GPx. In addition, coadministration of BSO changed the mechanism of BP elevation from H(2)O(2)-ERK to (O(2-.))-NO dependent in animals receiving leptin for 4 days, whereas NAC had the opposite effect in rats treated with leptin for 8 days. These results suggest that initial change in GSH redox status induces decrease in SOD/GPx ratio, which results in greater amount of (O)2-.)) versus H(2)O(2) in later phase of leptin treatment, thus shifting the mechanism of BP elevation from H(2)O(2)-ERK to (O(2-.))-NO dependent.

Waist-to-hip ratio, body mass index, and subsequent kidney disease and death

BACKGROUND

Chronic kidney disease (CKD) and obesity are important public health concerns. We examined the association between anthropomorphic measures and incident CKD and mortality.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Individual patient data pooled from the Atherosclerosis Risk in Communities Study and the Cardiovascular Health Study.

PREDICTORS

Waist-to-hip ratio (WHR), body mass index (BMI).

OUTCOMES & MEASUREMENTS

Incident CKD defined as serum creatinine level increase greater than 0.4 mg/dL with baseline creatinine level of 1.4 mg/dL or less in men and 1.2 mg/dL or less in women and final creatinine level greater than these levels, and, in separate analyses, estimated glomerular filtration rate (eGFR) decrease of 15 mL/min/1.73 m(2) or greater with baseline eGFR of 60 mL/min/1.73 m(2) or greater and final eGFR less than 60 mL/min/1.73 m(2). Multivariable logistic regression to determine the association between WHR, BMI, and outcomes. Cox models to evaluate a secondary composite outcome of all-cause mortality and incident CKD.

RESULTS

Of 13,324 individuals, mean WHR was 0.96 in men and 0.89 in women and mean BMI was 27.2 kg/m(2) in both men and women. During 9.3 years, 300 patients (2.3%) in creatinine-based models and 710 patients (5.5%) in eGFR-based models developed CKD. In creatinine-based models, each SD increase in WHR was associated with increased risk of incident CKD (odds ratio, 1.22; 95% confidence interval [CI], 1.05 to 1.43) and the composite outcome (hazard ratio, 1.12; 95% CI, 1.06 to 1.18), whereas each SD increase in BMI was not associated with CKD (odds ratio, 1.05; 95% CI, 0.93 to 1.20) and appeared protective for the composite outcome (hazard ratio, 0.94; 95% CI, 0.90 to 0.99). Results of eGFR-based models were similar.

LIMITATIONS

Single measures of creatinine, no albuminuria data.

CONCLUSIONS

WHR, but not BMI, is associated with incident CKD and mortality. Assessment of CKD risk should use WHR rather than BMI as an anthropomorphic measure of obesity.

An association between metabolic syndrome and the estimated glomerular filtration rate

OBJECTIVE

Metabolic syndrome (MetS) is a major public health problem. However, few studies have examined the significance of MetS as a risk factor for the development of chronic kidney disease (CKD) in the general Japanese population.

METHODS

Study participants without a clinical history of stroke, transient ischemic attack, myocardial infarction, angina, or renal failure (1,158 men, aged 61+/-15 years and 1,606 women, aged 63+/-12 years) were recruited from a single community. We examined the cross-sectional relationship between MetS and renal function as evaluated by estimated glomerular filtration rate (eGFR).

RESULTS

The presence of MetS was consistently associated with reduced eGFR, with the level of reduction proportional to the number of MetS components present. Multiple linear regression analysis using eGFR as an objective variable showed that BMI, DBP, antihypertensive drug use, high-density lipoprotein cholesterol, antilipidemic drug use and fasting blood glucose, which were components of MetS, were significantly and independently associated with eGFR, in addition to age and low-density lipoprotein cholesterol. Individuals with MetS showed a multivariate-adjusted odds ratio of 1.53 (95% confidence interval, 1.10-2.13) for CKD compared to those without MetS.

CONCLUSIONS

MetS was significantly associated with decreased eGFR in the general population.