Plasma leptin is associated with insulin resistance independent of age, body mass index, fat mass, lipids, and pubertal development in nondiabetic adolescents

Association between serum leptin concentrations and homeostasis model assessment-insulin resistance of 2.5 and higher in normal weight Japanese women

Normal weight insulin resistant phenotype was characterized in 251 Japanese female university students using homeostasis model assessment-insulin resistance. Birth weight, body composition at age 20, cardiometabolic traits and dietary intake were compared cross-sectionally between insulin sensitive (< 1.6, n = 194) and insulin resistant (2.5 and higher, n = 16) women. BMI averaged < 21 kg/m² and waist < 72 cm and did not differ between two groups. The percentage of macrosomia and serum absolute and fat-mass corrected leptin concentrations were higher in insulin resistant women although there was no difference in birth weight, fat mass index, trunk/leg fat ratio and serum adiponectin. In addition, resting pulse rate, serum concentrations of free fatty acids, triglycerides and remnant-like particle cholesterol were higher in insulin resistant women although HDL cholesterol and blood pressure did not differ. In multivariate logistic regression analyses, serum leptin (odds ratio:1.68, 95% confidential interval:1.08-2.63, p = 0.02) was associated with normal weight insulin resistance independently of macrosomia, free fatty acids, triglycerides, remnant-like particle cholesterol and resting pulse rate. In conclusion, normal weight IR phenotype may be associated with increased plasma leptin concentrations and leptin to fat mass ratio in young Japanese women, suggesting higher leptin production by body fat unit.

High free leptin index as the risk factor for childhood obesity in Indonesia: A case-control study

Identifying the risk factors is critical in preventing childhood obesity. Leptin concentration is elevated in obesity. High serum leptin levels are believed to reduce soluble leptin receptor (sOB-R) concentrations and are associated with leptin resistance. The free leptin index (FLI) is a biomarker of leptin resistance and the status of leptin action. This study aims to investigate the association between leptin, sOB-R, and FLI with measurements to diagnose obesity in children, such as BMI, waist circumference and waist-to-height ratio (WHtR). We conducted a case-control study in 10 elementary schools in Medan, Indonesia. The case group was children with obesity, while the control group was children with normal BMI. Leptin and sOB-R levels were measured from all the subjects using the ELISA method. Logistic regression analysis was employed to determine which factors were predictor variables of obesity. A total of 202 children between 6 and 12 years old were recruited for this study. Children with obesity showed significantly higher leptin levels and FLI and lower SOB-R levels FLI (p < .05) than control. The cut-off for WHtR in this study was 0.499 (sensitivity 90% and specificity 92.5%). Children with higher leptin levels had a higher risk of obesity based on BMI, waist circumference, and WHtR values.

Is the Leptin/Adiponectin Ratio a Better Diagnostic Biomarker for Insulin Resistance than Leptin or Adiponectin Alone in Adolescents?

Background: Recently, the leptin/adiponectin (L/A) ratio has been suggested as a novel predictor of cardio-metabolic and other chronic diseases. Aim: To evaluate the ability of leptin (L), adiponectin (A), and the L/A ratio in identifying high risk of insulin resistance IR in adolescents, adjusted by cardiorespiratory fitness, adherence to the Mediterranean diet, and body fat percentage. Subjects and methods: This is a cross-sectional analysis with 529 adolescents aged 12−18 years-old. Blood samples were taken to analyze glucose, insulin, leptin, and adiponectin levels. IR (homeostasis model assessment of insulin resistance (HOMA-IR) was estimated from fasting serum insulin and glucose). Results: Adiponectin, leptin, and L/A ratio were accurate to predict IR among adolescents. The optimal L/A cut-off value to indicate risk of IR development was >0.35 in boys and >0.97 in girls. Logistic analyses showed that the suggested cut-off points for adiponectin (girls: OR: 2.87 (1.26−6.53); p = 0.012); leptin (boys: OR: 5.23 (1.16−7.14) p = 0.006; girls: OR: 2.99 (1.10−8.09) p = 0.031), and the L/A ratio (boys: OR: 8.38 (2.6−26.8) p < 0.001; girls: OR: 6.1 (2.1−17.0) p < 0.001), were significant predictors of IR, after adjustments for age, pubertal stage, adherence to the Mediterranean diet, cardiorespiratory fitness, and body fat percentage. Conclusion: Leptin and L/A ratio were associated with IR risk, after adjustments for confounders in both sexes and adiponectin in girls. The L/A ratio seems to have a higher diagnostic accuracy to identify IR risk than adiponectin or leptin, in both sexes.

The association between variant rs9939609 in the FTO gene with free leptin index and the risk of obesity in the Indonesian children population

Background

Several studies have reported that fat mass and obesity-associated gene (FTO), especially the rs9939609 polymorphism, are associated with obesity and high leptin levels. The free leptin index (FLI) is known to be accurate in determining the function of leptin. The aim of this study was to determine the association between the rs9939609 variant in the FTO gene and FLI and the risk of obesity among children living in Medan, Indonesia.

Methods

This case–control study included 212 children aged 6–12 years who were genotyped for variants of the rs9939609 FTO gene. The case group consisted of children with obesity who were < 6 years old, and the control group had a normal body mass index and came from the Bataknese or Chinese ethnicities. Anthropometric measurements were performed. Serum leptin and soluble leptin receptor (sOB-R) levels were measured. Odds ratio and 95% confidence intervals were calculated to determine the risk of having obesity associated with the risk allele.

Results

In this study, there was no significant association between leptin, soluble leptin receptor, or free leptin index and the rs9939609 FTO gene; however, the risk allele (A) of FTO rs9939609 had a significant association with obesity in Chinese ethnicity subjects (p < 0.05). The AA/AT genotype had an increased risk of FLI 5.889 times compared to the TT genotype. Multivariate analysis showed that the rs9939609 polymorphism in the FTO gene played a role in obesity through the FLI.

Conclusion

It was concluded that the rs9939609 polymorphism played a significant role in obesity through FLI. Further studies are still needed.

A robust method for collider bias correction in conditional genome-wide association studies

Estimated genetic associations with prognosis, or conditional on a phenotype (e.g. disease incidence), may be affected by collider bias, whereby conditioning on the phenotype induces associations between causes of the phenotype and prognosis. We propose a method, 'Slope-Hunter', that uses model-based clustering to identify and utilise the class of variants only affecting the phenotype to estimate the adjustment factor, assuming this class explains more variation in the phenotype than any other variant classes. Simulation studies show that our approach eliminates the bias and outperforms alternatives even in the presence of genetic correlation. In a study of fasting blood insulin levels (FI) conditional on body mass index, we eliminate paradoxical associations of the underweight loci: COBLLI; PPARG with increased FI, and reveal an association for the locus rs1421085 (FTO). In an analysis of a case-only study for breast cancer mortality, a single region remains associated with more pronounced results.

The impact of sleep apnea syndrome on the altered lipid metabolism and the redox balance

Background

Obstructive sleep apnea (OSA) is a disorder with a significant risk for cardiovascular diseases. Dyslipidemia and redox imbalance belong to potential mechanisms linking OSA with the development of vascular diseases. The main aim of this study was the evaluation of the presence of lipid abnormalities in OSA patients, focusing on small dense low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions and determination of the redox imbalance by evaluating the marker of oxidative damage to plasma lipids - lipoperoxides.

Methods

The study included 15 male subjects with polysomnographically confirmed OSA and 16 male healthy controls. Plasma levels of total cholesterol, LDL and HDL and their subfractions, triacylglycerols and lipoperoxides were determined in all study individuals. Plasma LDL and HDL subfractions were separated by the Lipoprint system which is a polyacrylamide gel electrophoresis. Lipoperoxide levels were determined spectrophotometrically.

Results

OSA patients had significantly higher triacylglycerols, total cholesterol and LDL-cholesterol compared to healthy controls. HDL cholesterol was not significantly different. Of the LDL and HDL subfractions, OSA patients had significantly lower levels of atheroprotective LDL1 and large HDL subfractions and significantly higher levels of atherogenic small dense LDL3–7 and HDL8–10 subfractions. Lipoperoxide levels in patients with OSA were significantly elevated compared to healthy individuals.

Conclusion

The lipoprotein pro-atherogenic phenotype was found in individuals with OSA characterized by increased levels of atherogenic lipoprotein subfractions and reduced levels of atheroprotective subfractions. In addition, a plasma redox imbalance was found in patients with OSA compared to controls by detecting higher oxidative damage to lipids. Abnormalities in lipoprotein levels in patients with OSA, as well as the redox imbalance, could lead to an acceleration of the atherosclerotic process in predisposed individuals and thus represent a significant risk factor for vasular diseases.

Serum leptin as a mediator of the influence of insulin resistance on hepatic steatosis in youths with excess adiposity

BACKGROUND AND AIMS

The relationship between insulin resistance (IR) and hepatic steatosis (fatty liver) is well known; however, the extent to which the satiety hormone leptin acts as a confounder or mediator in this relationship is uncertain. We examined whether the association between IR and hepatic steatosis is mediated by leptin in Colombian adolescents with excess adiposity.

METHODS AND RESULTS

A total of 122 adolescents (mean age: 13.4 years; 68% girls) participated in the study. We assessed body composition, hepatic steatosis (as defined by the controlled attenuation parameter [CAP]), cardiometabolic risk factors (body mass index, waist circumference, body composition), biochemical variables (leptin, insulin, glucose, lipid profile, cardiometabolic Z-score, transaminases, etc.), and physical fitness (cardiorespiratory fitness and grip strength). Partial correlation, regression, and mediation analyses were conducted using the Barron and Kenny framework.

RESULTS

Ninety-two youths (75.4%) had IR. Mediation analysis revealed a positive relationship between Homeostasis Model Assessment-IR (HOMA-IR) and CAP (β_dir = 3.414, 95% confidence interval [CI]: 1.012 to 5.816, p < 0.001), which was attenuated when leptin was included in the model, thus indicating that leptin mediates this relationship (β_ind = 1.074, 95% CI: 0.349 to 2.686, p < 0.001). The percentage of the total effect mediated by leptin was 21%. Regarding sex, the mediation effect of leptin remains significant among boys (β_ind = 0.962, 95% CI: 0.009 to 2.615, p < 0.001), but not in girls (β_ind = 0.991, 95% CI: 1.263 to 5.483, p = 0.477).

CONCLUSIONS

The findings are clinically relevant to consider leptin levels as a surrogate marker of insulin sensitivity when assessing youths with excess adiposity and/or suspected Nonalcoholic hepatic steatosis or nonalcoholic fatty liver disease (NAFLD).

Association of insulin resistance and leptin receptor gene polymorphism in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic disease that is characterized by impaired glucose metabolism and insulin resistance. The objectives of the study were to evaluate the pattern of leptin receptor gene polymorphism Gln223Arg in T2DM and to identify its association with the serum leptin and insulin levels as well as with insulin resistance in diabetes.

METHODS

In this cross-sectional study, genotyping of leptin receptor was done for Gln223Arg alleles by PCR-restriction fragment length polymorphism in 39 patients with type 2 diabetes. Serum leptin and insulin levels were assayed using enzyme linked sorbent assay in 39 cases and 45 nondiabetic controls. Insulin resistance was calculated by the homeostasis model assessment of insulin resistance (HOMA-IR) formula. Statistical analysis was performed with Graph pad Instat version 3.

RESULTS

Hardy-Weinberg Equilibrium for the leptin receptor (LEPR) gene variants showed that alleles were in equilibrium. Leptin levels were insignificantly low in patients with diabetes compared to those in controls. Women in the control group showed significantly higher leptin levels (p < 0.05) compared with men. There was a significant difference in the serum insulin levels and insulin resistance (HOMA-IR) among patients with different genotypes (p = 0.04 and p = 0.0378, respectively).

CONCLUSION

Leptin receptor gene polymorphism affected glucose metabolism by altering insulin resistance and pancreatic beta cells. Thus, single-nucleotide polymorphism of LEPR may affect the pathogenesis of T2DM.

Prevalence and Clinical Characteristics of Children and Adolescents with Metabolically Healthy Obesity: Role of Insulin Sensitivity

Obesity represents a major risk factor for metabolic disorders, but some individuals, "metabolically healthy" (MHO), show less clinical evidence of these complications, in contrast to "metabolically unhealthy" (MUO) individuals. The aim of this cross-sectional study is to assess the prevalence of the MHO phenotype in a cohort of 246 overweight/obese Italian children and adolescents, and to evaluate their characteristics and the role of insulin resistance. Homeostasis model assessment-insulin resistance (HOMA-IR), insulin sensitivity index (ISI), insulinogenic index (IGI) and disposition index (DI) were all calculated from the Oral Glucose Tolerance Test (OGTT). MHO was defined by either: (1) HOMA-IR < 2.5 (MHO-IRes), or (2) absence of the criteria for metabolic syndrome (MHO-MetS). The MHO prevalence, according to MHO-MetS or MHO-IRes criteria, was 37.4% and 15.8%, respectively. ISI was the strongest predictor of the MHO phenotype, independently associated with both MHO-IRes and MHO-MetS. The MHO-MetS group was further subdivided into insulin sensitive or insulin resistant on the basis of HOMA-IR (either < or ≥ 2.5). Insulin sensitive MHO-MetS patients had a better metabolic profile compared to both insulin resistant MHO-MetS and MUO-MetS individuals. These data underscore the relevance of insulin sensitivity to identifying, among young individuals with overweight/obesity, the ones who have a more favorable metabolic phenotype.

Relationship between insulin resistance and adipocytokines: the mediator role of adiposity in children

Background: Leptin and adiponectin interact with each other in the modulation of obesity and insulin resistance (IR) and it is also important to consider the role of cardiorespiratory and muscular fitness in these relationships.Aim: To analyse the relationship between IR with adipocytokines in children, and to test the mediation effect of %BF (percentage of body fat) in the association of IR with leptin, adiponectin, and L/A ratio.Subjects and methods: This cross-sectional study comprised a sample of 150 schoolchildren, aged 6-11 years, from school in Porto Alegre, Brazil. The following variables were evaluated: cardiorespiratory fitness (CRF), muscular fitness (MF), percentage of body fat (%BF), and biochemical variables (leptin, adiponectin, glucose, and insulin).Results: IR was associated with leptin and L/A ratio, after adjustments for age, sex, sexual maturation, and CRF. When adjusted for age, sex, sexual maturation, and MF, an association was found between IR with leptin and L/A ratio. Moreover, %BF was a mediator in the association between IR and leptin, as well as IR and L/A ratio, explaining 54% and 57% of these associations, respectively.Conclusion: Leptin and L/A ratio are positively associated with IR after adjustments. Also, %BF is a mediator in the associations between IR and leptin and L/A ratio.

Does Eating-Away-from-Home Increase the Risk of a Metabolic Syndrome Diagnosis?

Rising frequency of eating-away-from-home (EAFH) is suspected to be correlated with several non-communicable diseases. This study adopted the Chinese Health and Nutrition Survey (CHNS) 2009 data to investigate the association between being diagnosed with the metabolic syndrome (MetS) and EAFH at different ages. Results showed that the association between EAFH and MetS varied at different ages and differed for males and females. EAFH was positively associated with a higher risk of getting MetS for males, especially for those aged between 45 and 60; while it was negatively associated with the risk of getting MetS for young females (<45) (all p < 0.05). In particular, EAFH was associated with a lower risk of getting high serum triglycerides (TGs), abdominal adiposity, elevated blood pressure, and impaired fasting blood glucose for young females, while higher risk of high serum TGs, abdominal adiposity, elevated blood pressure, and impaired fasting blood glucose for middle-aged males (all p < 0.05). In addition, a higher frequency of EAFH was associated with a higher risk of abdominal adiposity and elevated blood pressure for older women, and a lower risk of elevated blood pressure, and impaired fasting blood glucose for younger men (all p < 0.05). Our study implies that heterogeneous target strategies for preventing MetS in different subpopulation should be considered.

Contribution of obesity as an effect regulator to an association between serum leptin and incident metabolic syndrome

BACKGROUND

We investigated whether serum leptin can be a predictor for incident cases of MetS in a population-based study.

METHODS

This is a prospective cohort study of 1590 adults aged between 40 and 70 years, who did not have MetS in 2005-2008 (at baseline) and 2008-2011 (follow-up). The baseline serum leptin concentrations were measured by radioimmunoassay.

RESULTS

During an average of 2.8 years of follow-up, 113 men (17.1%) and 148 women (15.9%) developed MetS. In multivariable adjusted models, the odds ratio of incident MetS when comparing the lowest to the highest quartiles of leptin levels was 3.17 in men and 2.79 in women; nevertheless, the significance disappeared after adjusting for the body mass index (BMI). In subsidiary analyses by BMI, logistic regression analysis showed that subjects with the highest tertile of serum leptin level were 3.04 and 2.12 times more likely to have MetS than those with the lowest tertile in lean subjects (OR 3.04; 95% CI 1.44-6.41; p = .004 in men vs. OR 2.12; 95% CI 1.06-4.25; p = .036 in women, respectively).

CONCLUSIONS

Obesity is an effect regulator, which can predict an association between increased serum leptin level and the incidence of MetS in lean subjects.

The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease

Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.

Ability of Nontraditional Risk Factors and Inflammatory Biomarkers for Cardiovascular Disease to Identify High Cardiometabolic Risk in Adolescents: Results From the LabMed Physical Activity Study

PURPOSE

Then objective of this study was to evaluate the ability of several nontraditional cardiometabolic and inflammatory biomarkers in identifying high cardiometabolic risk in adolescents.

METHODS

A cross-sectional study was conducted with 529 Portuguese adolescents (267 girls) aged 14.3 ± 1.7 years. A clustered cardiometabolic risk score (body fat percentage, systolic blood pressure, ratio of total cholesterol to high-density lipoprotein cholesterol, triglycerides, homeostatic model assessment of insulin resistance, and negative values of cardiorespiratory fitness) was computed. The nontraditional cardiometabolic biomarkers assessed were complement factors (C3 and C4), C-reactive protein (CRP), fibrinogen, leptin, white blood cells (WBCs), albumin, interleukin-6, and a clustered score of inflammatory biomarkers (InflaScore) (C3, C4, CRP, fibrinogen, and leptin).

RESULTS

Receiver operating characteristic curves analyses showed that C3, C4, CRP, fibrinogen, leptin, and the InflaScore were able to present discriminatory ability in identifying an unfavorable cardiometabolic profile in both girls and boys (p <.01 for all). Logistic regression analyses showed that C3, C4, CRP, fibrinogen, leptin, the InflaScore (in both sexes), and WBC (boys) were associated with high cardiometabolic risk, independent of age, pubertal stage, socioeconomic status, or adherence to a Mediterranean diet (p <.05 for all).

CONCLUSIONS

C3, C4, CRP, fibrinogen, and leptin were associated with high cardiometabolic risk in both sexes and WBC in boys. In addition, the clustered inflammatory biomarkers seem to have a better diagnostic accuracy in identifying an unfavorable cardiometabolic profile than single biomarkers. Such biomarkers may have utility in motivating health professionals, public health workers, and adolescents' families toward lifestyle changes, improving prevention efforts early in life.

Leptin-induced basal Akt phosphorylation and its implication in exercise-mediated improvement of insulin sensitivity

Physical exercise is an efficient therapeutical tool in the management of insulin resistance (IR) and related metabolic diseases. Leptin, the well-known obesity hormone and the absence of which leads to IR, showed controversial effects on IR as research continues. Thus, in this study, a detailed investigation of the effect of leptin on exercise-mediated improvement of insulin sensitivity and its underlying mechanism was carried out. Using a rat model of chronic or acute swimming exercise training, we found that serum leptin increased 1 h after either acute exercise or the last session of chronic exercise, when impaired insulin action was observed in previous reports. However, chronic exercise reducd basal serum leptin levels and promoted insulin sensitivity compared with sedentary controls or rats subjected to one bout of aerobic exercise. Our animal results indicated the potential linkage between leptin and insulin sensitivity, which is further investigated in the skeletal muscle L6 cells. Leptin treatment in L6 cells promoted the basal levels of insulin signaling as well as glucose uptake, while blocking JAK2 signaling with either pharmacological intervention (JAK2 inhibitor AG490) or genetic manipulation (siRNA knockdown) decreased the basal levels of insulin signaling. Furthermore, leptin treatment inhibited insulin-stimulated insulin signaling and glucose uptake, while blocking JAK2 signaling restored leptin-attenuated insulin sensitivity. Taken together, our results demonstrated that reduced serum leptin, at least in part, contributes to exercise-mediated improvement of insulin sensitivity, indicating JAK2 as a potent therapeutical target of insulin resistance.

Interaction between prenatal pesticide exposure and a common polymorphism in the PON1 gene on DNA methylation in genes associated with cardio-metabolic disease risk-an exploratory study

BACKGROUND

Prenatal environmental conditions may influence disease risk in later life. We previously found a gene-environment interaction between the paraoxonase 1 (PON1) Q192R genotype and prenatal pesticide exposure leading to an adverse cardio-metabolic risk profile at school age. However, the molecular mechanisms involved have not yet been resolved. It was hypothesized that epigenetics might be involved. The aim of the present study was therefore to investigate whether DNA methylation patterns in blood cells were related to prenatal pesticide exposure level, PON1 Q192R genotype, and associated metabolic effects observed in the children.

METHODS

Whole blood DNA methylation patterns in 48 children (6-11 years of age), whose mothers were occupationally unexposed or exposed to pesticides early in pregnancy, were determined by Illumina 450 K methylation arrays.

RESULTS

A specific methylation profile was observed in prenatally pesticide exposed children carrying the PON1 192R-allele. Differentially methylated genes were enriched in several neuroendocrine signaling pathways including dopamine-DARPP32 feedback (appetite, reward pathways), corticotrophin releasing hormone signaling, nNOS, neuregulin signaling, mTOR signaling, and type II diabetes mellitus signaling. Furthermore, we were able to identify possible candidate genes which mediated the associations between pesticide exposure and increased leptin level, body fat percentage, and difference in BMI Z score between birth and school age.

CONCLUSIONS

DNA methylation may be an underlying mechanism explaining an adverse cardio-metabolic health profile in children carrying the PON1 192R-allele and prenatally exposed to pesticides.

Hyperleptinemia is associated with impaired pulmonary host defense

We have previously reported that obesity attenuates pulmonary inflammation in both patients with acute respiratory distress syndrome (ARDS) and in mouse models of the disease. We hypothesized that obesity-associated hyperleptinemia, and not body mass per se, drives attenuation of the pulmonary inflammatory response and that this e_ect could also impair the host response to pneumonia. We examined the correlation between circulating leptin levels and risk, severity, and outcome of pneumonia in 2 patient cohorts (NHANES III and ARDSNet-ALVEOLI) and in mouse models of diet-induced obesity and lean hyperleptinemia. Plasma leptin levels in ambulatory subjects (NHANES) correlated positively with annual risk of respiratory infection independent of BMI. In patients with severe pneumonia resulting in ARDS (ARDSNet-ALVEOLI), plasma leptin levels were found to correlate positively with subsequent mortality. In obese mice with pneumonia, plasma leptin levels were associated with pneumonia severity, and in obese mice with sterile lung injury, leptin levels were inversely related to bronchoalveolar lavage neutrophilia, as well as to plasma IL-6 and G-CSF levels. These results were recapitulated in lean mice with experimentally induced hyperleptinemia. Our findings suggest that the association between obesity and elevated risk of pulmonary infection may be driven by hyperleptinemia.

Carotenoids in Adipose Tissue Biology and Obesity

Cell, animal and human studies dealing with carotenoids and carotenoid derivatives as nutritional regulators of adipose tissue biology with implications for the etiology and management of obesity and obesity-related metabolic diseases are reviewed. Most studied carotenoids in this context are β-carotene, cryptoxanthin, astaxanthin and fucoxanthin, together with β-carotene-derived retinoids and some other apocarotenoids. Studies indicate an impact of these compounds on essential aspects of adipose tissue biology including the control of adipocyte differentiation (adipogenesis), adipocyte metabolism, oxidative stress and the production of adipose tissue-derived regulatory signals and inflammatory mediators. Specific carotenoids and carotenoid derivatives restrain adipogenesis and adipocyte hypertrophy while enhancing fat oxidation and energy dissipation in brown and white adipocytes, and counteract obesity in animal models. Intake, blood levels and adipocyte content of carotenoids are reduced in human obesity. Specifically designed human intervention studies in the field, though still sparse, indicate a beneficial effect of carotenoid supplementation in the accrual of abdominal adiposity. In summary, studies support a role of specific carotenoids and carotenoid derivatives in the prevention of excess adiposity, and suggest that carotenoid requirements may be dependent on body composition.

Assessment of cardiometabolic risk in children in population studies: underpinning developmental origins of health and disease mother-offspring cohort studies

Pregnancy and birth cohorts have been utilised extensively to investigate the developmental origins of health and disease, particularly in relation to understanding the aetiology of obesity and related cardiometabolic disorders. Birth and pregnancy cohorts have been utilised extensively to investigate this area of research. The aim of the present review was twofold: first to outline the necessity of measuring cardiometabolic risk in children; and second to outline how it can be assessed. The major outcomes thought to have an important developmental component are CVD, insulin resistance and related metabolic outcomes. Conditions such as the metabolic syndrome, type 2 diabetes and CHD all tend to have peak prevalence in middle-aged and older individuals but assessments of cardiometabolic risk in childhood and adolescence are important to define early causal factors and characterise preventive measures. Typically, researchers investigating prospective cohort studies have relied on the thesis that cardiovascular risk factors, such as dyslipidaemia, hypertension and obesity, track from childhood into adult life. The present review summarises some of the evidence that these factors, when measured in childhood, may be of value in assessing the risk of adult cardiometabolic disease, and as such proceeds to describe some of the methods for assessing cardiometabolic risk in children.

High prevalence of cardiometabolic risk factors in Hispanic adolescents: correlations with adipocytokines and markers of inflammation

This study assessed the association of cardiometabolic risk factors with systemic inflammation, insulin resistance, and adypocytokines in a Hispanic adolescent subgroup. A clinic-based sample of 101 Puerto Rican adolescents, 48 of whom were overweight or obese based on body mass index percentiles for age and sex, was recruited during 2010. Data were collected through interviews, blood pressure and anthropometric measurements, and blood drawing. Overall prevalence of the metabolic syndrome was 16.8 % and increased to 37.5 % among overweight/obese youth. The overweight/obese group exhibited significantly (p < 0.05) higher values for abdominal obesity measures, systolic blood pressure, triglycerides, insulin resistance, C peptide, high-sensitivity C reactive protein, fibrinogen, leptin, and IL-6 and lower levels of high density lipoprotein cholesterol, adiponectin, and IGF-1. Total adiponectin significantly correlated with most cardiovascular risk factors independent of sex, Tanner stage, and adiposity. Altered cardiometabolic and adipocytokine profiles were present in this Hispanic subgroup, reinforcing the need to strengthen strategies addressing childhood obesity.

Leptin and cardiometabolic risk factors in obese children and adolescents

AIM

To verify the relationship between leptin and cardiometabolic risk factors in obese children and adolescents.

METHODS

A cross-sectional study evaluated 200 children and adolescents treated in Campina Grande, Brazil, from April 2009 to March 2010. Leptin, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides were determined. The t-test was used to compare leptin means of two groups and analysis of variance to compare means of three groups. Multiple comparisons of pairs of group means were performed with Tukey's test. In all tests, a significance level of 0.05 was adopted.

RESULTS

The leptin sample mean was 22.7 ± 10.0 μg/L (95% confidence interval: 21.3 μg/L to 24.1 μg/L). Leptin was significantly higher in the following groups: female, teenager, increased waist circumference, high systolic blood pressure, elevated triglycerides hyperinsulinemia, insulin resistance and metabolic syndrome. Most cardiometabolic risk factors had higher means in the last quartile of leptin, except total-cholesterol, LDL-C and triglycerides levels. HDL-C was reduced in the last quartile of leptin. Simple linear regression analysis showed a significant negative correlation between leptin and HDL-C and a positive correlation between leptin and triglycerides, insulin, HOMA-IR, body mass index, waist circumference, and systolic and diastolic blood pressure. Multiple linear regression models showed an independent association between leptin and HDL-C, triglycerides, insulin, HOMA-IR, body mass index, waist circumference, systolic and diastolic blood pressure, after age and gender control.

CONCLUSION

Leptin may be a useful marker of metabolic syndrome and insulin resistance in obese adolescents.

Hyperleptinemia, adiposity, and risk of metabolic syndrome in older adults

Background. Abdominal adiposity and serum leptin increase with age as does risk of metabolic syndrome. This study investigates the prospective association between leptin and metabolic syndrome risk in relation to adiposity and cytokines. Methods. The Health, Aging, and Body Composition study is a prospective cohort of older adults aged 70 to 79 years. Baseline measurements included leptin, cytokines, BMI, total percent fat, and visceral and subcutaneous fat. Multivariate logistic regression was used to determine the association between leptin and metabolic syndrome (defined per NCEP ATP III) incidence after 6 years of follow-up among 1,120 men and women. Results. Leptin predicted metabolic syndrome in men (P for trend = 0.0002) and women (P for trend = 0.0001). In women, risk of metabolic syndrome increased with higher levels of leptin (compared with quintile 1, quintile 2 RR = 3.29, CI = 1.36, 7.95; quintile 3 RR = 3.25, CI = 1.33, 7.93; quintile 4 RR = 5.21, CI = 2.16, 12.56; and quintile 5 RR = 7.97, CI = 3.30, 19.24) after adjusting for potential confounders. Leptin remained independently associated with metabolic syndrome risk after additional adjustment for adiposity, cytokines, and CRP. Among men, this association was no longer significant after controlling for adiposity. Conclusion. Among older women, elevated concentrations of leptin may increase the risk of metabolic syndrome independent of adiposity and cytokines.

Leptin, vitamin D, and cardiorespiratory fitness as risk factors for insulin resistance in European adolescents: gender differences in the HELENA Study

The purpose of this study was to identify the relevance of a set of risk factors for insulin resistance in adolescents from Europe and to consider their possible gender-specific associations. The Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) was conducted in 1053 European adolescents (mean age, 14.9 years) in a school setting in 9 countries. Three anthropometric markers of body fat and a dietary index were calculated. Total energy intake was estimated from a questionnaire. C-reactive protein, leptin, and vitamin D were assessed, and physical activity, cardiorespiratory fitness, and muscular strength were measured. Center, socioeconomic status, pubertal status, and season were used as potential confounders. The main outcome was the homeostasis model assessment used as a marker of insulin resistance. Correlations, analyses of covariance, and logistic regression models were used. In males, leptin was the only risk factor for insulin resistance after adjusting for confounders including markers of body fat (odds ratios (ORs) from 1.49 to 1.60). In females, leptin, vitamin D, and fitness were the remaining independent risk factors for insulin resistance after adjustments (OR 2.11; 95% confidential interval (CI) 1.29-3.45; OR 0.50, 95% CI 0.31-0.80; and OR 0.54, 95% CI 0.33-0.87, respectively). Our observations suggest a gender dimorphism in the identification of risk factors for high insulin resistance. Preventive strategies should focus on improving modifiable factors such as cardiorespiratory fitness and on ensuring vitamin D sufficiency. Randomized controlled trials focusing on these strategies are necessary to test their efficacy.

Factors associated with development of excessive fatness in children and adolescents: a review of prospective studies

The purpose of this review was to examine the factors that predict the development of excessive fatness in children and adolescents. Medline, Web of Science and PubMed were searched to identify prospective cohort studies that evaluated the association between several variables (e.g. physical activity, sedentary behaviour, dietary intake and genetic, physiological, social cognitive, family and peer, school and community factors) and the development of excessive fatness in children and adolescents (5-18 years). Sixty-one studies met the eligibility criteria and were included. There is evidence to support the association between genetic factors and low physical activity with excessive fatness in children and adolescents. Current studies yielded mixed evidence for the contribution of sedentary behaviour, dietary intake, physiological biomarkers, family factors and the community physical activity environment. No conclusions could be drawn about social cognitive factors, peer factors, school nutrition and physical activity environments, and the community nutrition environment. There is a dearth of longitudinal evidence that examines specific factors contributing to the development of excessive fatness in childhood and adolescence. Given that childhood obesity is a worldwide public health concern, the field can benefit from large-scale, long-term prospective studies that use state-of-the-art measures in a diverse sample of children and adolescents.

Relationships between serum leptin level and severity of positive symptoms in schizophrenia

The adipocytokine leptin is a key mediator of energy homeostasis. Recent papers have suggested that leptin may also have roles in the brain however it is unclear whether leptin is connected to symptoms of mental disorders. In this study, we sought to clarify the relationships between serum leptin level and psychopathology in schizophrenia (SZ) patients. The severity of positive symptoms inversely correlated with the serum leptin levels among SZ patients. There was no correlation between leptin levels and negative symptoms or neurocognition. Our data suggest a role of leptin in SZ positive symptoms.

Racial differences in adiponectin and leptin in healthy premenopausal women

The aim of this article is to longitudinally investigate racial differences in serum adiponectin and leptin in European-American (EA) and African-American (AA) women in the overweight and weight-reduced states. Sixty-two EA and 58 AA premenopausal women were weight reduced from body mass index (BMI) 27-30 kg/m(2) to BMI ≤ 24. Fasting serum adiponectin and leptin were determined; body composition and intra-abdominal adipose tissue (IAAT) were measured with dual-energy X-ray absorptiometry and computed tomography, respectively. In repeated-measure MANOVA, there was a significant race effect for IAAT and total fat mass; compared to AA women, EA women had higher IAAT and total fat mass (p < 0.0001 and p = 0.027, respectively). In the mixed-model for adiponectin that adjusted for IAAT, limb fat, and total fat, race was significantly associated with adiponectin (p = 0.046). AA women had significantly lower adjusted adiponectin compared to EA women at baseline [7.67 (6.85, 8.60) vs. 9.32 (8.34, 10.4) μg/ml, p < 0.05] and following weight loss [9.75 (8.70, 10.9) vs. 11.8 (10.6, 13.2) μg/ml, p < 0.05]. In a mixed-model for leptin that adjusted for insulin, estradiol, and fat mass, race was significantly associated with leptin (p < 0.0001). AA women had significantly higher adjusted leptin compared to EA women at baseline [24.7 (22.3, 27.4) vs. 19.9 (18.1, 21.8) ng/dl, p < 0.05] and following weight loss [11.7 (10.2, 13.3) vs. 8.48 (7.50, 9.57) ng/dl, p < 0.05]. Despite having a more favorable body fat distribution, AA women had lower adjusted adiponectin and higher leptin. Differences in body composition and fat distribution do not appear to be significant factors in explaining lower adiponectin and higher leptin in AA women.

Obesity and suicide risk in adults--a systematic review

BACKGROUND

There is evidence from prospective studies that obesity is positively associated with depression. In contradiction to this, however, a number of studies have revealed that the number of completed suicides decreases with increasing BMI. The objective of this systematic review is to elucidate this ambiguous research field, providing an overview of literature examining the relationship between obesity and risk of suicide in adults (>18 years).

METHODS

Literature searches of the databases PubMed/Medline, PsychInfo, and Web of Sciences were conducted. Fifteen studies concerning completed suicide, suicide attempts and suicidal ideation met the inclusion criteria (seven prospective and eight cross-sectional studies).

RESULTS

Eight studies evaluating completed suicide reported an inverse relationship between BMI and suicide, meaning that obese people are less likely to commit suicide than people of low or normal weight, whereas one study showed no association and one showed a positive association. Studies about suicide attempts and ideation, on the other hand, found results that differed depending on gender. While obese woman reported more suicide attempts and suicidal ideation, obese men reported less attempts and thoughts.

DISCUSSION

The role of confounding variables such as age or psychiatric illness on suicide risk are discussed and remaining research questions are outlined, especially regarding the role of different underlying biological pathways and consideration of different classes of obesity.

Association between serum leptin concentrations and insulin resistance: a population-based study from China

BACKGROUND

Insulin resistance contributes to the cardio-metabolic risk. The effect of leptin in obese and overweight population on insulin resistance was seldom reported.

METHODS

A total of 1234 subjects (572 men and 662 women) aged ≥18 y was sampled by the procedure. Adiposity measures included BMI, waist circumference, hip circumference, WHR, upper arm circumference, triceps skinfold and body fat percentage. Serum leptin concentrations were measured by an ELISA method. The homeostasis model (HOMA-IR) was applied to estimate insulin resistance.

RESULTS

In men, BMI was the variable which was most strongly correlated with leptin, whereas triceps skinfold was most sensitive for women. More importantly, serum leptin levels among insulin resistant subjects were almost double compared to the subjects who had normal insulin sensitivity at the same level of adiposity in both men and women, after controlling for potential confounders. In addition, HOMA-IR increased significantly across leptin quintiles after adjustment for age, BMI, total energy intake, physical activity and smoking status in both men and women (p for trend <0.0001).

CONCLUSIONS

There was a significant association between HOMA-IR and serum leptin concentrations in Chinese men and women, independently of adiposity levels. This may suggest that serum leptin concentration is an important predictor of insulin resistance and other metabolic risks irrespective of obesity levels. Furthermore, leptin levels may be used to identify the cardio-metabolic risk in obese and overweight population.

Development of guidelines for assessing obesity in captive chimpanzees (Pan troglodytes)

Many captive chimpanzees (Pan troglodytes) are subjectively considered to be overweight or obese. However, discussions of obesity in chimpanzees are rare in the literature, despite the acknowledged problem. No study to date has systematically examined obesity in captive chimpanzees. This project develops guidelines for defining obesity in captive chimpanzees through the examination of morphometric and physiologic characteristics in 37 adult female and 22 adult male chimpanzees. During each animal's biannual physical exam, morphometric data was collected including seven skinfolds (mm), body mass index (BMI), waist-to-hip ratio (WHR), and total body weight (kg). The morphometric characteristics were correlated with triglycerides and serum glucose concentration, to test the utility of morphometrics in predicting relative obesity in captive chimpanzees. Abdominal skinfold (triglyceride: F=3.83, P=0.05; glucose: F=3.83, P=0.05) and BMI (triglyceride: F=10.42, p=0.003; glucose: F=6.20, P=0.02) were predictive of increased triglycerides and serum glucose in females; however no morphometric characteristics were predictive of relative obesity in males. Results suggest that no males in this population are overweight or obese. For females, there were additional significant differences in morphometric (skinfolds, BMI, WHR, total body weight) and physiologic measurements (systolic and diastolic blood pressure, red blood cells) between individuals classified overweight and those classified non-overweight. Skinfold measurements, particularly abdominal, seem to be an accurate measure of obesity and thus potential cardiovascular risk in female chimpanzees, but not males. By establishing a baseline for estimated body fat composition in female captive chimpanzees, institutions can track individuals empirically determined to be obese, as well as obesity-related health problems. Zoo Biol 0:1-12, 2007. (c) 2007 Wiley-Liss, Inc.

FTO gene is related to obesity in Chilean Amerindian children and impairs HOMA-IR in prepubertal girls

OBJECTIVE

The objective of this study was to investigate the allelic frequency of the fat mass and obesity-associated (FTO) gene (rs9939609) and its influences on obesity and metabolic risk biomarkers in a cohort of normal weight and obese Chilean children determining its ethnicity.

METHODS

A total of 136 normal weight children and 238 obese children (between 6 and 11 yr old) from an urban setting were recruited for this case-control study. The children were classified as normal weight [body mass index (BMI) ≥ 5th and < 85th percentiles] or obese (BMI >95th percentile), according to the international age- and gender-specific percentiles defined by the Center for Disease Control and Prevention. The analysis of serum markers was carried out using commercial kits. The FTO polymorphism was determined through a high-resolution melting enabled real time polymerase chain reaction. Ethnicity was determined by analyzing mitochondrial DNA by the restriction fragment length polymorphism method.

RESULTS

As much as 85% of the cohort was Amerindian. The minor A allele of rs9939609 was associated with obesity (odds ratio (OR): 1.422 [95% confidence interval (CI) 1.068-1.868] p = 0.015), calculated using an additive model. In sex-stratified analysis we found that the risk variant (A) of rs9939609 was associated with a higher homeostasis model of assessment for insulin (HOMA-IR) in prepubertal obese girls. In male carriers of the A allele, HOMA-IR showed no further deterioration than that already associated with obesity.

CONCLUSIONS

In summary, we confirm the association of the FTO gene single-nucleotide polymorphism rs9939609 with obesity in Chilean Amerindian children. Furthermore we show an association between the risk allele (A) and insulin resistance-related markers in prepubertal obese girls.

Association between metabolic syndrome and serum leptin levels in postmenopausal women

Menopausal status is associated with weight gain, increased central fat mass, abnormal lipid metabolism, insulin resistance and susceptibility to metabolic syndrome (MetS). Leptin is synthesised and secreted by adipocytes. Serum leptin levels are highly correlated with fat mass. We determined the association between MetS and serum leptin levels in 153 postmenopausal women. The difference in serum leptin level between MetS and non-MetS groups showed a statistical significance after adjusting for body mass index (BMI; 19.9 ± 9.5 vs 12.1 ± 5.9 ng/ml, p = 0.013). The indicator of abdominal obesity, waist-to-hip ratio (WHR) and visceral fat area (VFA), had a positive correlation with serum leptin level in non-obese subjects after adjusting for BMI (p = 0.017, p < 0.001, respectively). Of the components of MetS, abdominal obesity and the number of MetS components had a positive correlation with serum leptin level (p < 0.05, p < 0.001, respectively).

Obstructive sleep apnea syndrome in children

The clinical syndrome of obstructive sleep apnea (OSAS) in children is a distinct, yet somewhat overlapping disorder with the condition that occurs in adults, such that the clinical manifestations, polysomnographic findings, diagnostic criteria and treatment approaches need to be considered in an age-specific manner. Childhood OSAS has now become widely recognized as a frequent disorder and as a major public health problem. Pediatric OSAS, particularly when obesity is concurrently present, is associated with substantial end-organ morbidities and increased healthcare utilization. Although adenotonsillectomy (T&A) remains the first line of treatment, evidence in recent years suggests that the outcomes of this surgical procedure may not be as favorable as expected, such that post-T&A polysomnographic evaluation may be needed, especially in high-risk patient groups. In addition, incorporation of nonsurgical approaches for milder forms of the disorder and for residual OSAS after T&A is now being investigated.

Lipid metabolism in mammalian tissues and its control by retinoic acid

Evidence has accumulated that specific retinoids impact on developmental and biochemical processes influencing mammalian adiposity including adipogenesis, lipogenesis, adaptive thermogenesis, lipolysis and fatty acid oxidation in tissues. Treatment with retinoic acid, in particular, has been shown to reduce body fat and improve insulin sensitivity in lean and obese rodents by enhancing fat mobilization and energy utilization systemically, in tissues including brown and white adipose tissues, skeletal muscle and the liver. Nevertheless, controversial data have been reported, particularly regarding retinoids' effects on hepatic lipid and lipoprotein metabolism and blood lipid profile. Moreover, the molecular mechanisms underlying retinoid effects on lipid metabolism are complex and remain incompletely understood. Here, we present a brief overview of mammalian lipid metabolism and its control, introduce mechanisms through which retinoids can impact on lipid metabolism, and review reported activities of retinoids on different aspects of lipid metabolism in key tissues, focusing on retinoic acid. Possible implications of this knowledge in the context of the management of obesity and the metabolic syndrome are also addressed. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.

Serum leptin is associated with cardiometabolic risk and predicts metabolic syndrome in Taiwanese adults

BACKGROUND

Leptin is associated with cardiovascular disease (CVD); however, few studies have assessed its relationship with metabolic syndrome, especially in an Asian population. Therefore, the aim of the present study was to assess leptin levels and evaluate its association with CVD and metabolic syndrome.

METHODS

In 2009, 957 subjects, who underwent a routine physical examination and choose leptin examination, were selected to participate. Participants (269 females and 688 males) were stratified according to leptin level quartiles. Metabolic syndrome was defined by NCEP ATP III using waist circumference cutoffs modified for Asian populations, and CVD risk was determined using the Framingham Heart Study profile.

RESULTS

Leptin levels were correlated with CVD risk in men and women. With the exception of fasting plasma glucose, increased leptin levels were observed as factors associated with metabolic syndrome increased in both males and females. After adjusting for age, an association between leptin levels and metabolic syndrome was observed. After adjusting for age alone or with tobacco use, subjects in the highest leptin quartile had a higher risk of having metabolic syndrome than those in the lowest quartile (OR=6.14 and 2.94 for men and women, respectively). After further adjustment for BMI, metabolic syndrome risk remained significantly increased with increasing leptin quartiles in men. Finally, increased leptin levels were a predictor of metabolic syndrome in men and women.

CONCLUSIONS

Serum leptin levels are correlated with CVD risk and metabolic syndrome. Analysis of leptin as part of routine physical examinations may prove beneficial for early diagnosis of metabolic syndrome.

Characterization of a new animal model of metabolic syndrome: the DahlS.Z-Lepr(fa)/Lepr(fa) rat

Objective:

The DahlS.Z-Lepr^fa/Lepr^fa (DS/obese) rat strain was established from a cross between Dahl salt-sensitive rats and Zucker fatty (fa/fa) rats, the latter of which harbor a missense mutation in the leptin receptor gene (Lepr). We examined whether DS/obese rats might be a suitable animal model of metabolic syndrome in humans.

Methods:

The systemic pathophysiological and metabolic characteristics of DS/obese rats were determined and compared with those of homozygous lean littermates, namely, DahlS.Z-Lepr⁺/Lepr⁺ (DS/lean) rats.

Results:

Systolic blood pressure was higher in DS/obese rats fed a normal diet than in DS/lean rats at 11 weeks of age and thereafter. The survival rate of DS/obese rats was significantly lower than that of DS/lean rats at 18 weeks. Body weight, visceral and subcutaneous fat mass, as well as heart, kidney and liver weights, were increased in DS/obese rats at 18 weeks compared with DS/lean rats. Serum low-density lipoprotein (LDL)-cholesterol, triglyceride and insulin concentrations, as well as the ratio of LDL-cholesterol to high-density lipoprotein-cholesterol levels, were increased in DS/obese rats, whereas serum glucose concentration did not differ significantly between DS/obese and DS/lean rats. Creatinine clearance was decreased and urinary protein content was increased in DS/obese rats, which also manifested lipid accumulation in the liver and elevation of serum alanine aminotransferase levels.

Conclusion:

These results show that the phenotype of DS/obese rats is similar to that of humans with metabolic syndrome, and that these animals may thus be an appropriate model for this condition.

Association of plasma leptin levels and insulin resistance in diabetic women: a cross-sectional analysis in an Iranian population with different results in men and women

OBJECTIVES

The objective of this study was to assess the association of serum leptin levels with insulin resistance (IR), metabolic syndrome (MetS), lipid levels, and glucose control in an Iranian type 2 diabetic population.

FINDINGS

In this cross-sectional analysis, 132 type 2 diabetic patients (79 women) and 71 healthy non-diabetic and non-hypertensive individuals (40 women; as control subjects) were included. Homeostasis model assessment (HOMA) of insulin values ≥ 1.8 for females and 1.7 for males was regarded as the cut-point of IR. MetS was defined according to updated 2005 NCEP ATP III criteria. The leptin correlated with HOMA-IR values without adjustment (r = 0.24; p < 0.005) and with adjustment for sex and diabetes (r = 0.44; p < 0.005). Sex had significant effect on the BMI adjusted association of HOMA-IR (quintiles) and leptin (df = 4 F(12.7) = 3.5; p = 0.011). In diabetic women (but not men), leptin levels were different between those with and without IR (27.3 ± 1.9 vs. 18.2 ± 3.3; p < 0.05). BMI adjusted leptin values were different between subjects with and without MetS (22.2 ± 1.7 vs.14.8 ± 1.2; p < 0.001). No association was noticed between BMI-adjusted leptin with glycated hemoglobin or blood lipid levels.

CONCLUSIONS

In this study, plasma leptin concentration correlated with IR independent of the effect of obesity in female but not male diabetic subjects.

Gender differences exist in the association of leptin and adiponectin levels with insulin resistance parameters in prepubertal Arab children

AIM

Differences in correlations between leptin, adiponectin and insulin resistance in children exist in different ethnic populations. No such information is available in Arab children. This study aims to fill this gap.

METHODS

Three hundred and twenty-five prepubertal children were recruited in this cross-sectional study. Body mass index (BMI), waist and hip circumferences and fasting glucose were measured by standard procedures. Serum insulin, leptin and adiponectin were assayed by ELISA.

RESULTS

Leptin and adiponectin levels were significantly correlated with anthropometric parameters, HOMA-IR and insulin in all subjects and with fasting glucose in girls only. Correlations of adiponectin with HOMA-IR and insulin in boys and of leptin with insulin in girls were independent of BMI, waist and hip circumferences.

CONCLUSION

Gender differences exist in the distribution of adipocytokines in prepubertal children. The associations of adipocytokines with obesity biomarkers in prepubertal children suggest a causal link between childhood obesity and the risk of an early diabetes onset.

Adipocytokines and bone mineral density in adolescent female athletes

AIM

 To evaluate the relationships of visfatin, adiponectin and leptin with bone mineral density (BMD) and bone mineral content (BMC) in adolescent female athletes with different training patterns.

METHODS

This study involved 170 healthy 13-15-year-old girls divided into six groups based on activity: sport games (i.e. basketball, volleyball, badminton) (n=49), track sprint (n=24), rhythmic gymnastics (n=23), swimming (n=24), cross-country skiing (n=17) and sedentary controls (n=33). BMD and BMC at femoral neck and lumbar spine (L2-L4) were measured using dual-energy X-ray absorptiometry. Visfatin, adiponectin, leptin, insulin and glucose were measured, and the insulin resistance index was calculated using homeostasis model assessment.

RESULTS

There were no relationships found between visfatin concentrations and bone mineral parameters in adolescent female athletes or controls. Adiponectin was inversely correlated to BMD and BMC of femoral neck and lumbar spine (r=-0.47-0.62) in the swimmer group only, but after adjustments for age, height and body mass these associations disappeared. Leptin concentrations correlated with bone mineral parameters even after adjusting for age, height and body mass (r=0.42-0.63) in the gymnast group only.

CONCLUSION

We may conclude that after adjustment, leptin is the only adipokine of those measured that correlates to femoral neck and lumbar spine BMD and femoral neck BMC in the rhythmic gymnast group.

Telmisartan ameliorates hyperglycemia and metabolic profile in nonobese Cohen-Rosenthal diabetic hypertensive rats via peroxisome proliferator activator receptor-gamma activation

The importance of hypertension treatment has expanded beyond blood pressure management to include additional risk factors, mainly diabetes. It was considered of interest to test the effect of telmisartan, an angiotensin receptor 1 antagonist and peroxisome proliferator activator receptor-gamma partial agonist, on Cohen-Rosenthal diabetic hypertensive nonobese (CRDH) rats, a unique model combining both pathologies. Its effect was examined on fat-derived and inflammatory agents in CRDH. To determine the extent of the drug's peroxisome proliferator activator receptor-gamma modulating beneficial metabolic actions, results were compared with those obtained with valsartan and rosiglitazone in CRDH and Cohen diabetic rat (CDR). Telmisartan and valsartan were given in drinking water at 3 and 12 mg/kg/d, whereas rosiglitazone (3 mg/kg/d) was given as food admixture for a period of 5 months. Blood pressure, glucose, insulin, adiponectin, leptin, and tumor necrosis factor alpha were examined. Telmisartan and valsartan significantly (P < .01) reduced blood pressure, whereas telmisartan and rosiglitazone considerably reduced blood glucose levels to normoglycemic levels (P < .01) in these 2 strains. Insulin levels were not affected by telmisartan and valsartan but were slightly reduced by rosiglitazone in CDR. In contrast to valsartan, adiponectin was significantly (60%, P < .01) increased by telmisartan in both CDR and CRDH, whereas rosiglitazone induced a 60% and 180% increase in CRDH and CDR animals, respectively, on day 30 of treatment. Co-treatment with GW9662 averted telmisartan-induced rise of adiponectin. Tumor necrosis factor alpha declined in telmisartan-treated rats, less so with rosiglitazone, but not valsartan. Telmisartan also induced downsizing of epididymal adipocytes compared with valsartan. Leptin levels were significantly increased by valsartan (P < .05) but reduced by telmisartan and rosiglitazone. The telmisartan-induced increase in adiponectin was most probably associated with a decrease in glucose and tumor necrosis factor alpha levels. Therefore, in addition to its hypotensive effect, telmisartan demonstrated beneficial thiazolidinedione-like effects.

Adipokines and cardiometabolic function: How are they interlinked?

OBJECTIVE

Adipokines contribute directly to the coexistence of insulin resistance and endothelial dysfunction. Most studies focus on a single adipokine. We therefore investigated the independent relationships of leptin, adiponectin, tumor necrosis factor-alpha, resistin and visfatin, as well as the gut hormone ghrelin with blood pressure and insulin resistance. Secondly we evaluated the interrelationships of adipokines and ghrelin in concert with various cardiometabolic markers.

METHODS AND RESULTS

Caucasian women (N=115) with varying levels of obesity (aged 31.3 + or - 9.18 years) were included. Significant correlations of leptin, adiponectin, ghrelin and visfatin with mean arterial pressure (p<0.05) disappeared after adjustment for age, body mass index and waist circumference. But significant correlations with insulin resistance (HOMA) (for leptin, adiponectin and ghrelin) remained significant after adjustments. Factor analyses yielded five factors, but two main clusters, namely a metabolic syndrome cluster (including leptin, adiponectin and ghrelin) and a vascular atherosclerotic cluster (including tumor necrosis factor-alpha, visfatin and resistin).

CONCLUSION

Factor analyses identified patterns which indicate specific roles of the various adipokines. Leptin, adiponectin and ghrelin were more closely related to insulin resistance and central obesity as core components of the metabolic syndrome. Visfatin, tumor necrosis factor-alpha and resistin seem to direct their effects onto the vascular system possibly by means of mechanisms such as inflammation, vasoconstriction and coagulation.

Visceral fat accumulation in Japanese high school students and related atherosclerotic risk factors

AIM

To investigate the factors that influence visceral fat accumulation in adolescence, we performed a medical examination of high school students and assessed abdominal fat thickness and fatty change of the liver.

METHODS

A cohort of 374 Japanese high school students aged 15-16 years (193 boys and 181 girls) in public high schools in Chiba prefecture were enrolled. Anthropometric parameters, blood cell count, blood chemistry and adipocytokine levels were measured. Preperitoneal fat thickness (PFT) and echoic contrast of the liver were measured by ultrasonography.

RESULTS

Anthropometric parameters, systolic blood pressure, blood cell count, ALT, AST, FBS, gamma-GTP, HDL-C, LpL, UA, adiponectin, resistin and leptin levels differed between sexes. Multivariate regression analysis revealed that leptin was the most appropriate marker for PFT in both sexes (p<0.0001). Visceral obesity, categorized as PFT exceeding 8 mm, was observed in 9.6% of all students. Boys with visceral obesity showed apparent liver dysfunction, hyperlipidemia, hyperinsulinemia, and high leptin and low adiponectin levels. Overall, 16.6% of boys and 30.4% of girls showed hepatorenal echo contrast positivity. Boys with visceral obesity and fatty liver had more risk factors for atherosclerosis.

CONCLUSIONS

Physical examination of high school students is important for early detection of atherosclerosis.

Obesity and low-grade inflammation: a paediatric perspective

Childhood obesity is a major public health problem. Low-grade inflammation, a hallmark characterizing adult obesity, may be a pivotal mechanism linking obesity to its numerous systemic complications, with adipose tissue depots secreting and producing inflammatory mediators and visceral fat displaying an increased inflammatory profile. While knowledge is relatively scarce regarding the importance of the adipose tissue inflammation process in children, identifying its contribution in childhood obesity and the associated influences of age, sex, weight status, growth, and adipose depot phenotypes are crucial for understanding physiopathology and implementing early intervention strategies. We review the latest research linking obesity and inflammation in childhood focusing on serum inflammatory markers and the effectiveness of lifestyle interventions in improving systemic inflammation. Generally, there are significant correlations between body mass index and increased c-reactive protein and decreased adiponectin levels in children; these levels tend to be improved in interventions resulting in approximately 5% weight loss, regardless of the type or length of intervention. There is a need for further research measuring other inflammatory mediators (e.g. tumour necrosis factor (TNF)-alpha, IL-6, IL-8) and histological studies examining immune cell infiltration in adipose tissue depots in obese children.