Relationship between adiponectin and ambulatory blood pressure in obese adolescents

Relationship between adiponectin and blood pressure in obese Latino adolescent boys with a family history of type 2 diabetes

INTRODUCTION

Adipokines are associated with several pathological states including, metabolic syndrome, obesity, insulin resistance and type 2 diabetes. One of these adipokines, adiponectin is of particular interest as it has been shown to have numerous anti-inflammatory effects, However, the association between adiponectin and blood pressure remains inconclusive especially in the Latino adolescent with obesity.

PURPOSE

To investigate the relationship between plasma adiponectin and blood pressure in Latino adolescents' boys with obesity and a with a family history of Type 2 diabetes.

METHODS

Thirty two Latino adolescent males with obesity aged 14-17 years with a family history of type 2 diabetes underwent a frequently sampled glucose tolerance test (FSIVGTT) to measure insulin sensitivity. Body composition was assessed using dual energy x-ray absorptiometry. Obesity was defined as having a BMI percentile ≥95. Blood pressure was assessed using the Dinamap automated blood pressure monitor, and the average of three readings was used in the analysis. Fasting plasma adiponectin was determined using radioimmunoassay.

RESULTS

There were moderate positive significant correlations for adiponectin and Systolic blood pressure(SBP) (rho = 0.436, p < 0.027) and Diastolic blood pressure(DBP) (rho = 0.41,p < 0.028). A multivariate liner regression showed that plasma adiponectin could significantly detect 19% of the variance in SBP (p = 0.017, and 33% for DBP (p = 0.017). In a simple linear regression adiponectin was not related to any of our variables (p < 0.05).

CONCLUSION

In conclusion, adiponectin was positively and significantly correlated to blood pressure in Latino adolescent with obesity. Future studies should investigate this relationship in a large sample of Latino adolescent youth.

Relationship between Adiponectin and Blood Pressure in Obese Latino Adolescent Boys with a Family History of Type 2 Diabetes

INTRODUCTION

Adipokines are associated with several pathological states including, metabolic syndrome, obesity, insulin resistance and type 2 diabetes. One of these adipokines, adiponectin is of particular interest as it has been shown to have numerous anti-inflammatory effects, However, the association between adiponectin and blood pressure remains inconclusive especially in the obese Hispanic adolescent.

PURPOSE

to investigate the relationship between plasma adiponectin and blood pressure in obese Latino adolescents' boys with a family history of Type 2 diabetes.

METHODS

Thirty two obese Latino male adolescents aged 14-17 years with a family history of type 2 diabetes underwent a frequently sampled glucose tolerance test (FSIVGTT) to measure insulin sensitivity. Body composition was assessed using dual energy x-ray absorptiometry. Obesity was defined as having a BMI percentile 395. Blood pressure was assessed using the Dinamap automated blood pressure monitor, and the average of three readings was used in the analysis. Fasting plasma adiponectin was determined using radioimmunoassay.

RESULTS

There was a strong positive significant correlation for adiponectin and Systolic blood pressure(SBP) (p< 0.027) and a moderate, positive significant correction for Diastolic blood pressure(DBP) (p< 0.028). A multivariate liner regression showed that plasma adiponectin could significantly predict 19% of the variance in SBP (p=0.017, and 33% for DBP (p=0.017).

CONCLUSION

In conclusion, adiponectin was positively and significantly correlated to blood pressure in obese Latino adolescent youth. Future studies should investigate this relationship in a large sample of Latino adolescent youth.

Obesity, Adipose Tissue and Vascular Dysfunction

Cardiovascular diseases are the leading cause of death worldwide. Overweight and obesity are strongly associated with comorbidities such as hypertension and insulin resistance, which collectively contribute to the development of cardiovascular diseases and resultant morbidity and mortality. Forty-two percent of adults in the United States are obese, and a total of 1.9 billion adults worldwide are overweight or obese. These alarming numbers, which continue to climb, represent a major health and economic burden. Adipose tissue is a highly dynamic organ that can be classified based on the cellular composition of different depots and their distinct anatomical localization. Massive expansion and remodeling of adipose tissue during obesity differentially affects specific adipose tissue depots and significantly contributes to vascular dysfunction and cardiovascular diseases. Visceral adipose tissue accumulation results in increased immune cell infiltration and secretion of vasoconstrictor mediators, whereas expansion of subcutaneous adipose tissue is less harmful. Therefore, fat distribution more than overall body weight is a key determinant of the risk for cardiovascular diseases. Thermogenic brown and beige adipose tissue, in contrast to white adipose tissue, is associated with beneficial effects on the vasculature. The relationship between the type of adipose tissue and its influence on vascular function becomes particularly evident in the context of the heterogenous phenotype of perivascular adipose tissue that is strongly location dependent. In this review, we address the abnormal remodeling of specific adipose tissue depots during obesity and how this critically contributes to the development of hypertension, endothelial dysfunction, and vascular stiffness. We also discuss the local and systemic roles of adipose tissue derived secreted factors and increased systemic inflammation during obesity and highlight their detrimental impact on cardiovascular health.

Serum adiponectin and resistin: Correlation with metabolic syndrome and its associated criteria among temiar subtribe in Malaysia

BACKGROUND AND OBJECTIVES

Metabolic syndrome (MetS) is characterized as a cluster of metabolic disorder including increased blood pressure, elevated blood glucose level, high cholesterol level and visceral fat obesity. Polypeptide hormones such as adiponectin and resistin play a significant role in glucose and lipids metabolism, liver and pancreas function. This study aimed to investigate the relationship between serum adiponectin and resistin with MetS criteria among Temiar subtribe in Kuala Betis.

MATERIALS AND METHODS

This cross sectional study involved 123 subjects from Temiar subtribe in Kuala Betis, Gua Musang, Kelantan. MetS criteria were measured according to standard protocol by modified National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) guideline. Anthropometric and biochemical measurements were performed including serum adiponectin and resistin for every study subjects.

RESULTS

Serum adiponectin was significantly lower in MetS subjects (7.98 ± 5.65 ng/ml) but serum resistin was found to be significantly higher in MetS subjects (11.22 ± 6.34 ng/ml) compared to non-MetS subjects with p < 0.001 and p = 0.002 respectively. Serum adiponectin was negatively correlated with most of the cardio-metabolic risk factors; BMI, waist circumference, systolic and diastolic blood pressure, fasting blood glucose, triglyceride and total cholesterol. Serum resistin was found to be positively correlated with BMI, waist circumference, fasting blood glucose and total cholesterol.

CONCLUSION

The difference in serum adiponectin and resistin level among MetS individuals indicated the potential of serum adiponectin and resistin to be used as a biomarker for the diagnosis of MetS among Temiar subtribe.

Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents

These pediatric hypertension guidelines are an update to the 2004 "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents." Significant changes in these guidelines include (1) the replacement of the term "prehypertension" with the term "elevated blood pressure," (2) new normative pediatric blood pressure (BP) tables based on normal-weight children, (3) a simplified screening table for identifying BPs needing further evaluation, (4) a simplified BP classification in adolescents ≥13 years of age that aligns with the forthcoming American Heart Association and American College of Cardiology adult BP guidelines, (5) a more limited recommendation to perform screening BP measurements only at preventive care visits, (6) streamlined recommendations on the initial evaluation and management of abnormal BPs, (7) an expanded role for ambulatory BP monitoring in the diagnosis and management of pediatric hypertension, and (8) revised recommendations on when to perform echocardiography in the evaluation of newly diagnosed hypertensive pediatric patients (generally only before medication initiation), along with a revised definition of left ventricular hypertrophy. These guidelines include 30 Key Action Statements and 27 additional recommendations derived from a comprehensive review of almost 15 000 published articles between January 2004 and July 2016. Each Key Action Statement includes level of evidence, benefit-harm relationship, and strength of recommendation. This clinical practice guideline, endorsed by the American Heart Association, is intended to foster a patient- and family-centered approach to care, reduce unnecessary and costly medical interventions, improve patient diagnoses and outcomes, support implementation, and provide direction for future research.

Circadian and ultradian cardiovascular rhythmicity in obese children

Altered circadian and ultradian blood pressure (BP) and heart rate (HR) rhythmicity have been described in diseases with increased cardiovascular risk. We analyzed cardiovascular rhythmicity in obese children. BP and HR rhythmicity was assessed with Fourier analysis from 24-h ambulatory BP measurements in 75 obese children and compared with an age- and gender-matched, lean healthy reference group of 150 subjects. Multivariate regression analysis was applied to identify significant independent factors explaining variability of rhythmicity. Prevalence of 24- and 6-h BP rhythmicity in the obese group was lower (p = 0.03 and p = 0.02), whereas the prevalence of HR rhythmicity was comparable in both groups. Excluding hypertensive participants, the results remained similar. Twenty-four-hour BP and HR acrophase were delayed in obese children (p = 0.004, p < 0.0001), 24-h BP amplitude did not differ (p = 0.07), and 24-h HR amplitude was blunted (p = < 0.0001). BP Mesor in the obese group was higher (p = 0.02); HR Mesor did not differ (p = 0.1). Multivariate regression analysis failed to identify a single anthropometric or blood pressure parameter explaining the variability of BP and HR rhythmicity.

CONCLUSION

Prevalence and parameters of circadian and ultradian BP and HR rhythmicity in obese children are altered compared to a healthy reference group, independent of preexisting hypertension.

WHAT IS KNOWN

• Altered cardiovascular rhythmicity has been described in children with different diseases such as primary hypertension or chronic renal failure. What is New: • This study reveals altered cardiovascular rhythmicity in obese children compared to an age and gender-matched healthy reference group independent from preexisting hypertension.

The Association of Pediatric Obesity With Nocturnal Non-Dipping on 24-Hour Ambulatory Blood Pressure Monitoring

BACKGROUND

Obesity has been linked with abnormal nocturnal dipping of blood pressure (BP) in adults, which in turn is associated with poor cardiovascular outcomes. There are few data regarding abnormal dipping status in the obese pediatric population. The goal of this study was to further describe the relationship between obesity and non-dipping status on ambulatory blood pressure monitor (ABPM) in children.

METHODS

We conducted a cross-sectional study using a database of patients aged 5-21 years who had undergone 24-hour ABPM at Seattle Children's Hospital from January 2008 through May 2014. Subjects were grouped by body mass index (BMI) into lean (BMI 15th-85th percentile) and obese (BMI >95th percentile) groups.

RESULTS

Compared to lean subjects (n = 161), obese subjects (n = 247) had a prevalence ratio (PR) for non-dipping of 2.15, adjusted for race (95% confidence interval (CI) = 1.25-3.42). Increasing severity of obesity was not further associated with nocturnal non-dipping. Nocturnal non-dipping was not associated with left ventricular hypertrophy (PR = 1.01, 95% CI = 0.71-1.44).

CONCLUSIONS

These results suggest that in children, just as in adults, obesity is related to a relatively decreased dipping in nocturnal BP.

Association of adiponectin and metabolic syndrome in adolescents: the caspian- III study

Background

This study aimed to investigate the associations between metabolic syndrome (Mets) and adiponectin concentrations in Iranian adolescents.

Methods

This study was conducted as a sub-study of a national school- based surveillance program in 10–18 year- old students from 27 provinces in Iran. Plasma adiponectin was measured in 180 randomly selected participants. Metabolic syndrome (Mets) was defined based on the Adult Treatment Panel III (ATP- III) criteria modified for the pediatric age group. Multiple logistic regression analyses were used to evaluate the association between adiponectin and cardiometabolic risk factors.

Results

The median of adiponectin concentrations was significantly lower among participants with Mets [2.95 μg/ml (interquartile range 2.72–3.30)] compared with subjects without Mets [4.55 μg/ml (interquartile range 3.02–5.75)]. Adiponectin showed significant negative association with higher number of Mets components (P- trend < 0.05). Significant correlations were observed between adiponectin concentrations and metabolic parameters, except blood pressure.

Significant inverse association existed between adiponectin levels and presence of Mets (OR, 0.21; 95%CI: 0.10–0.45; p < 0.001). In multivariate models, this association remained significant after adjustment for other risk factors (OR, 0.18; 95%CI: 0.07–0.47; p < 0.001.

Conclusions

Adiponectinhas inverse association with cardiometabolic parameters in Iranian adolescents, and it is a determinant of Mets independent of other risk factors. These findings can be used in comparison with other ethnic groups. Further longitudinal studies are necessary to assess the clinical impact of such inverse association.

Development of hypertension in overweight adolescents: a review

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

Pathophysiology of hypertension in obese children: a systematic review

Hypertension is increasingly common in overweight and obese children. The mechanisms behind the development of hypertension in obesity are complex, and evidence is limited. In order to effectively treat obese children for hypertension, it is important to have a deeper understanding of the pathophysiology of hypertension in obese children. The present review summarizes the main factors associated with hypertension in obese children and discusses their potential role in its pathophysiology. Systematic searches were conducted in PubMed and EMBASE for articles published up to October 2014. In total, 60 relevant studies were included. The methodological quality of the included studies ranged from weak to strong. Several factors important in the development of hypertension in obese children have been suggested, including endocrine determinants, such as corticosteroids and adipokines, sympathetic nervous system activity, disturbed sodium homeostasis, as well as oxidative stress, inflammation and endothelial dysfunction. Understanding the pathophysiology of hypertension in overweight and obese children is important and could have implications for its screening and treatment. Based on solely cross-sectional observational studies, it is impossible to infer causality. Longitudinal studies of high methodological quality are needed to gain more insight into the complex mechanisms behind the development of hypertension in obese children.

The effect of antenatal factors and postnatal growth on serum adiponectin levels in children

Low levels of serum adiponectin (i.e. hypoadiponectinaemia) are a marker of cardiometabolic risk in overweight children. It is not clear whether early-life factors may play a role in the development of hypoadiponectinaemia. We investigated whether antenatal factors and postnatal growth are associated with childhood adiponectin levels. This was an observational study in a birth cohort (Vulnerable Windows Cohort Study). Anthropometry was measured at birth, at 6 weeks, every 3 months up to 2 years and then every 6 months. Fasting glucose, insulin, lipids and adiponectin were measured at a mean age 11.5 years. Data on 323 children were analysed with age- and sex-adjusted multivariate analyses. The sizes of mother, placenta, fetus and newborn were not significantly associated with adiponectin levels. Current weight, body mass index (BMI), fat mass, waist circumference, glucose, insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR)], triglycerides and systolic blood pressure were inversely related to adiponectin (P < 0.05). Faster growth in BMI during late infancy and childhood was associated with lower adiponectin levels (P < 0.05). After adjusting for current waist circumference, faster growth in BMI during early infancy was positively associated with adiponectin (P < 0.01). Faster growth in BMI during childhood was inversely associated (P < 0.001). These associations were similar after adjusting for HOMA-IR. We concluded that antenatal factors are not determinants of childhood adiponectin levels. Faster growth in BMI during infancy is associated with higher levels, whereas faster rates during childhood are associated with hypoadiponectinaemia. Hypoadiponectinaemia is a marker of a more adverse cardiometabolic profile in Afro-Caribbean children.

Primary hypertension in childhood

There is growing concern about elevated blood pressure in children and adolescents, because of its association with the obesity epidemic. Moreover, cardiovascular function and blood pressure level are determined in childhood and track into adulthood. Primary hypertension in childhood is defined by persistent blood pressure values ≥ the 95th percentile and without a secondary cause. Preventable risk factors for elevated blood pressure in childhood are overweight, dietary habits, salt intake, sedentary lifestyle, poor sleep quality and passive smoking, whereas non-preventable risk factors include race, gender, genetic background, low birth weight, prematurity, and socioeconomic inequalities. Several different pathways are implicated in the development of primary hypertension, including obesity, insulin resistance, activation of the sympathetic nervous system, alterations in sodium homeostasis, renin-angiotensin system and altered vascular function. Prevention of adult cardiovascular disease should begin in childhood by regularly screening for high blood pressure, counseling for healthy lifestyle and avoiding preventable risk factors.

Blood pressure reclassification in adolescents based on repeat clinic blood pressure measurements

The common assumption is that blood pressure (BP) will decrease on subsequent readings. The objective of this study is to examine the prevalence and direction of BP classification change with repeat measurements and compare common clinical characteristics of groups of patients who do and do not have a change in BP classification. A nationally representative subsample of 1725 adolescents aged 13 to 18 years from the National Health and Nutrition Survey were analyzed. Three BP measurements were obtained. Patients were classified based on the first and the average of 3 BP measurements as having normal BP, hypertension, and/or prehypertension. Of the 1725 adolescents, 1569 (90.9%) maintained BP classification, 107 (6.2%) had a reduction in their classification, and 49 (2.9%) had an increase in their classification. Comparing the two groups that changed BP classification to the group without change, C-reactive protein and body mass index (BMI) z score were significantly higher in the groups that had a change in BP classification (P=.02 and <.001, respectively). After adjusting for other variables, higher BMI value was significantly associated with change in BP classification. With repeat measurements, the majority (~91%) did not have a change in classification. Obesity was a significant predictor of the 9% that had a change in classification. Repeat BP measurements in obese adolescents may lead to more accurate classification of BP status.

The changing face of pediatric hypertension in the era of the childhood obesity epidemic

Historically, hypertension in childhood was thought to be an uncommon diagnosis, usually related to an underlying condition, most often parenchymal renal disease. Primary hypertension in childhood was felt to be quite rare. However, the worldwide childhood obesity epidemic has had a profound impact on the frequency of hypertension and other obesity-related conditions with the result that primary hypertension should now be viewed as one of the most common health conditions in the young. This review will present updated data on the prevalence of hypertension in children and adolescents, the impact of the childhood obesity epidemic on hypertension prevalence and blood pressure levels, shifts in how often primary hypertension is being diagnosed in childhood, and an overview of the pathophysiology of obesity-related hypertension. It is hoped that improved understanding of the significance of these issues will lead to improved recognition and treatment, which will be the key to averting an epidemic of cardiovascular disease in adulthood.

Health impact in children and adolescents

Obesity in children and adolescents is associated with multiple comorbidities, including metabolic, cardiovascular, gastrointestinal, pulmonary, orthopedic and psychological disorders. In fact, cardiovascular and metabolic impairments in childhood and adolescence constitute major risk factors for developing cardiovascular disease in adulthood. Thus, obesity in childhood and adolescence leads to a higher morbidity and mortality in adulthood. Therefore, strong emphasis must be laid on the prevention and therapy of childhood obesity. Treatment requires a multidisciplinary and multiphase approach including dietary management, physical activity, pharmacotherapy and bariatric surgery. This paper reviews the different comorbidities of childhood obesity supporting the notion of a multidisciplinary therapy concept.

Hemodynamic and biochemical benefits of the objective measurement of fluid status in hemodialysis patients

Subtle fluid imbalance can cause poor clinical outcomes among hemodialysis patients. However, the traditional subjective assessment of fluid status may be inadequate. We evaluated whether the objective measurement and optimization of fluid status could be beneficial for hemodynamic and biochemical parameters in hemodialysis patients. We enrolled 120 hemodialysis patients, who were clinically euvolemic for at least 3 months. Based on the results of a body composition monitor, we divided the patients into the following two groups: the hyperhydrated group (post hemodialysis fluid overload ≥ 1.1 L) and the dehydrated group (post hemodialysis fluid overload < -1.1 L). We reduced the patient's body weight in the hyperhydrated group and raised the body weight in the dehydrated group towards normohydration (-1.1 L ≤ fluid overload < 1.1 L) for 16 weeks. Forty-four of 120 patients were in the hyperhydrated group, and 18 of 120 patients in the dehydrated group. After 16 weeks, systolic blood pressure and pulse pressure decreased in the hyperhydrated group, while there was no increase in blood pressure in the dehydrated group after the intervention. Serum levels of monocyte chemotactic protein-1, an inflammatory marker, gradually decreased in the hyperhydrated group, and serum adiponectin levels, an anti-atherogenic biomarker, increased in the two groups. We found that hyperhydrated patients contributed over 1/3 of the participants despite enrolling clinically euvolemic patients and that body composition monitor-guided optimization of body fluid status may lead to improvement of inflammatory markers and anti-atherogenic adipokines as well as hemodynamic parameters in hemodialysis patients.

Association of adipokines with cardiovascular risk factors in low birth weight children: a case-control study

Our aim was to investigate plasma levels of adiponectin, monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) in low birth weight (LBW) children and to determine correlations among these adipokines and birth weight and cardiovascular disease risk factors. In a case-control study, the concentrations of adiponectin, MCP-1 and PAI-1 were measured in 180 schoolchildren (ages 6-11 years). MCP-1 and PAI-1 levels were significantly elevated in LBW children. Conversely, adiponectin concentration was significantly reduced in these children. Similar findings were observed after adjustment for current age, gender and abdominal circumference. Because the children with LBW had altered adipokine levels, as well as higher abdominal circumference, HOMA-IR and systolic blood pressure (SBP), we evaluated the correlation among these variables. These analyses showed that adiponectin levels were inversely correlated with systolic blood pressure (SBP) (r = -0.501; P < 0.001), HOMA-IR (r = -0.293; P = 0.023) and waist circumference (r = -0.317; P = 0.014). The proinflammatory markers were positively correlated with HOMA-IR (PAI-1: r = 0.358; P = 0.005) and waist circumference (PAI-1: r = 0.571; P < 0.001 and MCP-1: r = 0.267; P = 0.039).

CONCLUSION

Adipokines levels were correlated with cardiovascular risk factors in LBW children, and these compounds could be involved in the mechanism that links birth weight to the development of cardiovascular diseases in adulthood.

Masked hypertension is prevalent in children with sickle cell disease: a Midwest Pediatric Nephrology Consortium study

BACKGROUND

The prevalence of hypertension and abnormal blood pressure (BP) patterns on 24-h ambulatory BP monitoring (ABPM) remains unknown in children with sickle cell disease (SCD).

METHODS

Thirty-eight asymptomatic children with sickle cell disease (SCD) (12 HbSS receiving routine care, 13 HbSC, and 13 HbSS receiving chronic transfusion therapy) underwent 24-h ABPM. Average clinic BP, demographic and biochemical characteristics were collected.

RESULTS

Median age was 13 years (range 11-16), body mass index (BMI) 19.1 kg/m(2) (range 18.2-21.1), and 50% were male. Seventeen subjects (43.6%) had ambulatory hypertension, while 4 (10.3%) were hypertensive based on their clinic BP. Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) dip were 8.3 ± 5.9% and 14.7 ± 7.6% respectively. Twenty-three subjects (59%) had impaired SBP dipping, 7 (18%) had impaired DBP dipping, and 5 (13%) had reversed dipping. Clinic and ABP classification were modestly correlated (rho = 0.38, P = 0.02).

CONCLUSION

Abnormalities in ABP measurements and patterns in children with SCD are prevalent and require more attention from heath care providers. ABPM is a valuable tool in identifying masked hypertension and abnormalities in circadian BP.

Relationship between Adiponectin Level, Insulin Sensitivity, and Metabolic Syndrome in Type 1 Diabetic Patients

Objective. Adiponectin is known to be decreased in insulin resistance (IR) and metabolic syndrome (MS) which can be present in patients with type 1 diabetes mellitus (T1DM). The aim of this study was to evaluate the relationship between adiponectin level, MS, and insulin sensitivity in T1DM. Research Design and Methods. The study included 77 T1DM patients divided into two groups based on the total plasma adiponectin median value. Insulin sensitivity was calculated with the equation for eGDR, and MS was defined according to International Diabetes Federation criteria. Results. Patients with higher adiponectin level (n = 39) had significantly lower waist circumference (P < 0.002), fasting venous glucose levels (P < 0.001), higher HDL3-cholesterol (P = 0.011), and eGDR (P = 0.003) in comparison to the group with lower adiponectin who showed higher prevalence of MS (P = 0.045). eGDR increased for 1.09 mg/kg(-1) min(-1) by each increase of 1  µ g/mL total fasting plasma adiponectin (P = 0.003). In the logistic regression model, adiponectin was inversely associated with the presence of MS (P = 0.014). Conclusion. Higher adiponectin concentration is associated with lower prevalence of MS in T1DM. Whether higher adiponectin concentration has a protective role in the development of the MS in T1DM needs to be clarified in future follow-up studies.

Hypertension and obesity: epidemiology, mechanisms and clinical approach

Obesity-related hypertension in pediatric patients is becoming more prevalent around the world as a consequence of the childhood obesity epidemic. Hypertension and the metabolic abnormalities associated with obesity will significantly increase the health risks for these children as they grow into adulthood. The pathophysiology of obesity-related hypertension is complex, and multiple potential mechanisms likely contribute to the development of higher blood pressure in obese children. These include hyperinsulinemia, activation of the renin-angiotensin-aldosterone system, stimulation of the sympathetic nervous system, abnormalities in adipokines such as leptin, direct effects of perinephric fat on the renal parenchyma, and cytokines acting at the vascular endothelial level. As in any child with elevated blood pressure, diagnostic evaluation should focus on confirmation of hypertension, determine if an underlying cause can be identified and whether hypertensive target organ damage is present. Therapy should begin with lifestyle modifications, but will often need to include one or more antihypertensive medications.

Pediatric ambulatory blood pressure monitoring: indications and interpretations

The prevalence of hypertension in children and adolescents is increasing, especially in obese and ethnic children. The adverse long-term effects of hypertension beginning in youth are known; therefore, it is important to identify young patients who need intervention. Unfortunately, measuring blood pressure (BP) is difficult due to the variety of techniques available and innate biologic variation in BP levels. Ambulatory BP monitoring may overcome some of the challenges clinicians face when attempting to categorize a young patient's BP levels. In this article, the authors review the use of ambulatory BP monitoring in pediatrics, discuss interpretation of ambulatory BP monitoring, and discuss gaps in knowledge in usage of this technique in the management of pediatric hypertension.

Cross-sectional association between blood pressure, in vivo insulin sensitivity and adiponectin in overweight adolescents

AIMS

To examine the cross-sectional relationship between blood pressure (BP) and (1) in vivo insulin sensitivity (IS) and (2) circulating adiponectin levels in overweight adolescents, and to determine if these relationships are driven by adiposity.

METHODS

Sixty-five white pubertal overweight adolescents underwent a hyperinsulinemic-euglycemic clamp to measure IS. Body composition and abdominal adiposity were determined by dual energy X-ray absorptiometry and computed tomography scan. BP was measured by an automated sphygmomanometer every 10 min over 1 h, between 06:00 and 07:00 a.m.

RESULTS

In vivo IS was not associated with BP after adjustment for adiposity measurements (body mass index, percentage body fat or abdominal adiposity). However, adiponectin was inversely related to systolic BP independent of adiposity.

CONCLUSION

Our findings demonstrate that in overweight adolescents the relationship between in vivo IS and systolic BP is mediated through adiposity. However, the association between adiponectin and BP is independent of adiposity suggestive of a potential modulatory role of adiponectin in BP regulation.

Relationships between renin, aldosterone, and 24-hour ambulatory blood pressure in obese adolescents

Renin-angiotensin system (RAS) activation and abnormalities of ambulatory blood pressure (ABP) are present in obesity, but relationships between components of the RAS and ABP have not been defined in the young. Anthropometric measurements and 24-h ABP were obtained on 30 obese adolescents with and without type 2 diabetes mellitus. Plasma renin activity (PRA), aldosterone, and other cardiovascular risk factors were measured. Median PRA levels were 2.5 [interquartile range (IQR), 1.7-4.1] ng/mL/h and were higher in the diabetic subjects compared with the nondiabetics. Females had significantly higher PRA than males 3.2 (IQR, 2-4.8) versus 1.8 (IQR, 1.1-2.9) ng/mL/h (p = 0.04) and were more obese. BMI Z score and PRA were significantly correlated (rho = 0.46, p < 0.001). PRA inversely correlated with 24-h systolic ABP (rho = -0.46, p = 0.02) and strongly with 24-h pulse pressure (rho = -0.61, p = 0.001). Aldosterone levels were also correlated with 24-h pulse pressure (rho = -0.46, p = 0.02). In multivariate models, lower PRA was independently associated with 24-h systolic blood pressure. In this study, PRA was positively correlated with BMI, but the relationships between components of the RAS and ABP were inverse. Further studies are needed to define the pathophysiologic relationship between RAS components and blood pressure regulation in obese youth.

Regulation of vascular tone by adipocytes

Recent studies have shown that adipose tissue is an active endocrine and paracrine organ secreting several mediators called adipokines. Adipokines include hormones, inflammatory cytokines and other proteins. In obesity, adipose tissue becomes dysfunctional, resulting in an overproduction of proinflammatory adipokines and a lower production of anti-inflammatory adipokines. The pathological accumulation of dysfunctional adipose tissue that characterizes obesity is a major risk factor for many other diseases, including type 2 diabetes, cardiovascular disease and hypertension. Multiple physiological roles have been assigned to adipokines, including the regulation of vascular tone. For example, the unidentified adipocyte-derived relaxing factor (ADRF) released from adipose tissue has been shown to relax arteries. Besides ADRF, other adipokines such as adiponectin, omentin and visfatin are vasorelaxants. On the other hand, angiotensin II and resistin are vasoconstrictors released by adipocytes. Reactive oxygen species, leptin, tumour necrosis factor α, interleukin-6 and apelin share both vasorelaxing and constricting properties. Dysregulated synthesis of the vasoactive and proinflammatory adipokines may underlie the compromised vascular reactivity in obesity and obesity-related disorders.

Adipokines and blood pressure control

PURPOSE OF REVIEW

In contrast to previous understanding, adipocytes are now known to produce an array of factors collectively termed 'adipokines', several of which have effects on the cardiovascular system. The marked rise in prevalence of obesity warrants investigation into the role of adipocyte-derived factors in the regulation of blood pressure. For example, dysregulated production of specific adipokines in the setting of obesity may contribute to hypertension commonly experienced in obese patients. This editorial highlights current concepts for regulation of adipokine production by adipocytes and their potential role in blood pressure regulation.

RECENT FINDINGS

Adipocytes synthesize and release several factors that have been linked to blood pressure control, including adiponectin, leptin, angiotensin, perivascular relaxation factors and resistin. Increasing evidence suggests that aberrant production and release of these factors from adipocytes may contribute to the high prevalence of hypertension in the obese population. However, additional studies are warranted to define precise mechanisms for blood pressure regulation by these factors, and to delineate their role in obesity-related hypertension.

SUMMARY

Studies aimed at determining the role of adipocyte-derived factors in blood pressure regulation during normal physiology and in the setting of obesity are needed.

Altered cardiovascular rhythmicity in children with white coat and ambulatory hypertension

Adults with ambulatory hypertension or white coat hypertension (WCH) display abnormal cardiovascular rhythms. We studied cardiovascular rhythms by Fourier analysis of 24-h ambulatory blood pressure (BP) measurement profiles in 129 hypertensive children, 54 children with WCH, and 146 age-, height-, and gender-matched healthy subjects. The day/night mean arterial pressure ratio was lower in hypertensive and patients with WCH compared with controls (1.13 versus 1.16 versus 1.21, respectively; p < 0.0001). Eighty-five percent of controls were dippers compared with 74% of WCH (n.s.) and 64% of patients with ambulatory hypertension (p < 0.0001). The prevalence of 24-h rhythms was similar among the groups, but prevalence of 12-h BP rhythms was increased in hypertensive (67%) and WCH (72%) compared with controls (51%, p < 0.0001). The amplitudes of the 24-, 8-, and 6-h BP rhythms were reduced in hypertensive and WCH compared with controls (p < 0.05). Hypertensive and patients with WCH displayed delayed 24-, 12-, 8-, 6-h acrophases in comparison with controls (p < 0.05). In conclusion, hypertensive children exhibit abnormal cardiovascular rhythmicity compared with controls, especially a higher prevalence of nondipping compared with normotensive children. Abnormalities in patients with WCH are intermediate between healthy children and patients with ambulatory hypertension.

Hypertension in adolescents

In adults, hypertension has long been perceived as a public health problem. By contrast, its impact in childhood is far less appreciated. In fact, quite often, high blood pressure in children is not even diagnosed. Blood pressure is a vital sign that is routinely obtained during a physical examination of adults, but only very seldom in children. The diagnosis of hypertension in children is complicated because 'normal' blood pressure values vary with age, sex and height. As a consequence, almost 75% of the cases of arterial hypertension and 90% of the cases of prehypertension in children and adolescents are currently undiagnosed. Furthermore, adolescence hypertension is increasing in prevalence as the prevalence of pediatric obesity has increased. Ambulatory blood pressure monitoring is a useful method for risk evaluation in adolescents. In addition to being viewed as an important cardiovascular risk factor in adolescents, elevated blood pressure should prompt a thorough search for other modifiable risk factors that, if treated, might reduce teenagers' risk of developing cardiovascular disease in adulthood. Thus, assessing blood pressure values in children represents one of the most important measurable markers of cardiovascular risk later in life and a major step in preventive medicine.