Steroid Metabolism in Children and Adolescents With Obesity and Insulin Resistance: Altered SRD5A and 20α/20ßHSD Activity.

Alterations in glucocorticoid metabolism may contribute to the development of obesity and insulin resistance (IR). Obesity in turn affects the androgen balance. The peripheral metabolism of steroids is equally an important determinant of their bioavailability and activity. The aim of this study was to evaluate steroid metabolism in obese children and to define which enzyme alterations are associated with IR. Clinical characteristics and anthropometric measurements were determined in 122 obese children and adolescents (72 girls, 50 boys) aged 8 - 18 years. 26 of them (21.3%) were diagnosed with IR (13 boys, 13 girls). Routine laboratory tests were performed and 24h urinary steroid excretion profiles were analyzed by gas chromatography/mass spectrometry. Positive relationship between 5α-reductase (SRD5A) activity and IR was found. According to the androsterone to etiocholanolone (An/Et) ratio the activity of SRD5A was significantly increased in obese children with IR, but the difference remained insignificant once the 5α-dihydrotestosterone to testosterone (5αDHT/T) ratio was considered. Furthermore, this relationship persisted in boys but was not observed in girls. The activity of 20α-hydroxysteroid dehydrogenase (20αHSD) and 20ß-hydroxysteroid dehydrogenase (20ßHSD) was reduced only in obese girls with IR. Conclude, in the context of obese children and adolescents with IR, we surmise that increased SRD5A represents a compensatory mechanism to reduce local glucocorticoid availability. This phenomenon is probably different in the liver (restriction) and in the adipose tissue (expected increase in activity). We show significant changes in 20αHSD and 20ßHSD activity in obese girls with IR, but it is difficult to clearly determine whether the activity of these enzymes is an indicator of the function in their ovaries or adrenal glands.

Association of AMY1A/AMY2A copy numbers and AMY1/AMY2 serum enzymatic activity with obesity in Mexican children.

BACKGROUND: Mexican children are characterized by a high-starch intake diet and high prevalence of obesity. OBJECTIVES: To investigate the association of AMY1A/AMY2A copy numbers (CNs) and AMY1/AMY2 serum enzymatic activity with childhood obesity in up to 427 and 337 Mexican cases and controls. METHODS: Anthropometric and dietary starch intake data were collected. CN of AMY1A/AMY2A and AMY1/AMY2 serum enzymatic activity were determined using droplet digital PCR (ddPCR) and enzymatic colorimetry, respectively. An individual participant level data meta-analysis of association between AMY1A CNVs and obesity was also performed. RESULTS: A positive association between AMY1A/AMY2A CNs and their corresponding AMY1/AMY2 serum enzyme activity was observed in children with normal weight and obesity. The serum enzyme activity of AMY1 and AMY2 was negatively associated with childhood obesity risk, and the association was restricted to kids eating medium/high amount of starch (Pinteraction = .004). While no association between AMY1A and AMY2A CNs and childhood obesity was observed in our sample, we confirmed a significant association between AMY1A CN and obesity in a meta-analysis of 3100 Mexican children. CONCLUSIONS: Our data suggest that genetically determined salivary and pancreatic amylase activity can increase/decrease the risk of obesity in Mexican children, this effect being blunted by a low-starch diet.

Associations of maternal and fetal SCD-1 markers with infant anthropometry and maternal diet: Findings from the ROLO study.

BACKGROUND: Elevated stearoyl-CoA desaturase 1 (SCD-1) activity showed associations with obesity in cross-sectional studies. In non-pregnant populations, nutrition regulates SCD-1 transcription and activity. OBJECTIVE: To investigate the longitudinal associations of maternal and fetal SCD-1 activity markers with infant anthropometry up to 2 years of age, and to explore how selected dietary intakes modulate SCD-1 activity in pregnancy. METHODS: As a secondary analysis from the ROLO intervention study, which was conducted in a population at risk for macrosomia, non-esterified fatty acids (NEFA) from maternal plasma at 13 and 28 weeks' gestation and in cord blood were measured via liquid-chromatography-mass-spectrometry. Fatty acid ratios 18:1/18:0 and 16:1/16:0 were used as markers for SCD-1 activity ('desaturation indices', DIs). Relationships of DIs with infant anthropometry up to 2 years of age and maternal dietary parameters during pregnancy were investigated using adjusted linear regression models and p-values correction for multiple testing. RESULTS: 18:1/18:0, but not 16:1/16:0, was associated with measures of infant anthropometry at birth (maternal and fetal markers) and up to 2 years of age (maternal markers only). Dietary intakes did not show strong associations with 18:1/18:0, but 16:1/16:0 was associated with absolute and relative dietary intakes. CONCLUSIONS: In a population at risk for macrosomia, maternal SCD-1 activity measured via 18:1/18:0 was involved in the fetal programming of infant obesity, but could not be substantially modulated by short-term diet in pregnancy. CLINICAL TRIAL REGISTRATION: ISRCTN Registration number: ISRCTN54392969 (http://www.isrctn.com/ISRCTN54392969).

Increased liver echogenicity and liver enzymes are associated with extreme obesity, adolescent age and male gender: analysis from the German/Austrian/Swiss obesity registry APV.

BACKGROUND: Childhood obesity is often associated with non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease in pediatrics. METHODS: This multi-center study analyzed liver echogenicity and liver enzymes in relation to obesity, age, gender and comorbidities. Data were collected using a standardized documentation software (APV) from 1.033 pediatric patients (age: 4-18 years, body mass index = BMI: 28-36 kg/m2, 50% boys) with overweight (BMI >90th percentile), obesity (BMI >97th percentile) or extreme obesity (BMI > 99.5th percentile) and obesity related comorbidities, especially NAFLD from 26 centers of Germany, Austria and Switzerland. Liver enzymes aspartate aminotransferase (AST), alanine-aminotransferase (ALT) and gamma glutamyltransferase (gammaGT) were evaluated using 2 cut-off values a) > 25 U/L and b) > 50 U/L. Multiple logistic regression models were used for statistical analysis. RESULTS: In total, 44% of the patients showed increased liver echogenicity. Liver enzymes > 25 U/L were present in 64% and > 50 U/L in 17%. Increased liver echogenicity was associated with elevated liver enzymes (> 25 U/L: odds ratio (OR) = 1.4, 95% CI: 1.1-1.9, P < 0.02; > 50 U/L: OR = 3.5, 95% CI: 2.4-5.1, P < 0.0001). Extreme obesity, adolescence and male gender were associated with increased liver echogenicity (extreme obesity vs overweight OR = 3.5, 95% CI: 1.9-6.1, P < 0.0001; age > 14 years vs age < 9 years OR = 2.2, 95% CI: 1.4-3.5, P < 0.001; boys vs girls OR = 1.6, 95% CI: 1.2-2.0, P < 0.001) and elevated liver enzymes (extreme obesity vs overweight > 25 U/L: OR = 4.1, 95% CI: 2.4-6.9, P < 0.0001; > 50 U/L: OR = 18.5, 95% CI: 2.5-135, P < 0.0001; age > 14 years vs age < 9 years > 50 U/L: OR = 1.9, 95% CI: 1.0-3.7, P > 0.05; boys vs girls > 25 U/L: OR = 3.1, 95% CI: 2.4-4.1, P < 0.0001; > 50 U/L: OR = 2.1, 95% CI: 1.5-2.9, P < 0.0001). Impaired glucose metabolism showed a significant correlation with elevated liver enzymes > 50 U/L (OR = 4.4, 95% CI: 1.6-11.8, P < 0.005). Arterial hypertension seemed to occur in patients with elevated liver enzymes > 25 U/L (OR 1.6, 95% CI: 1.2-2.0, P < 0.005). CONCLUSIONS: NAFLD is strongly related to extreme obesity in male adolescents. Moreover impaired glucose tolerance was observed in patients with elevated liver enzymes > 50 U/L, but arterial hypertension was only present in patients with moderately elevated liver enzymes > 25 U/L.

Association of Salivary Amylase (AMY1) Gene Copy Number with Obesity in Alabama Elementary School Children.

Salivary amylase (AMY1) is the most abundant enzyme in human saliva, responsible for the hydrolysis of α-1,4 glycosidic linkages that aids in the digestion of starch. Recently studies have shown that the copy number of AMY1 is associated with obesity; however, the data varies with location. One-third of children are overweight/obese in Alabama. In this study, we aim to determine the relationship between the copy number of AMY1 gene and obesity measurements in children from Alabama. One hundred twenty-seven children aged between 6 to 10 years participated in this study. Anthropometric measurements were measured using WHO recommendations. Genomic DNA was extracted from saliva, and the copy number of the AMY1 gene was estimated by digital PCR. The association between AMY1 copy number and obesity measurements was analyzed by linear regression. The mean AMY1 copy number significantly decreased in overweight/obese (6.21 ± 1.48) compared to normal weight (7.97 ± 2.35) children. AMY1 copy number inversely associated with the obesity measurements. African Americans had a stronger association between low AMY1 copy number and obesity compared to white/European Americans. Our findings suggest that overweight/obese children have a low AMY1 copy number and the effect is more prominent in African Americans.

[Carbohydrate-related nutritional and genetic risks of obesity for indigenous northerners].

By the end of the 2010-s the prevalence of obesity among the indigenous people of the North approached to the all-Russia one and the speed of the spread of other metabolic disorders exceeded the average all-country levels. Aim of this review is to analyze data on the increase in consumption and variety of sugars coupled with a genetic specificity of regulation of saccharidase activity and their possible impact on the matters. Results. It have been shown that the traditional protein-lipid-based northern type diet has substantially changed and now contains a high proportion of carbohydrates. The carbohydrate per capita consumption among the indigenous people of the North has reached the all-Russia average level (40 kg per year) which exceeds the European average of 36.2 kg per year. The variety of food disaccharides has also considerably increased. The daily consumption of sucrose, at the beginning of the 20th century it was the only sugar contained in the store-bought foods, increased from 30 g in the 1930s to 63-65 g in the 1990s. In addition, the proportion of sucrose dropped to 60-70 per cent, while the contribution of other disaccharides (lactose, trehalose) reached 30-40 per cent. Daily starch consumption has also increased and got close to the national average (males 228.5 g, females 157.5 g per day). Such a diet in itself increases the risk of metabolic disorders and obesity. The high prevalence of the genotypes that determine reduced levels or inability to produce sucrase-isomaltase, lactase, trehalase, salivary and pancreatic amylases among northerners becomes a negative cofactor. The evolutionary driven and embodied in genotype reduced ability of the indigenous Arctic people to digest complex carbohydrates is in a conflict with the growing consumption of sugars and starchy foods in modern conditions. The northern people have a high proportion of carriers of the AG deletion in SI gene (3.5-14.3% against 0.05-0.2% among Europeans) which determines malabsorption of sucrose. The CC/LCT genotype (96.6% in northerners, 36-49% in Russians) presumes lactose intolerance and is associated with the risk of childhood obesity. The occurrence of A allele in the rs2276064 locus of TREH gene (trehalose intolerance; 31.3-58.9% in northerners, 1.9% in Europeans) increases the probability of the onset of type 2 diabetes mellitus. According to preliminary estimates, 28-52% of the northerners completely lost AMY gene that precludes or drastically reduces the ability to digest starch. A reduction in the number of copies of AMY gene (the average number of copies AMY2A - 4, in, in northerners it is 1.0-1.4) is associated with overweight and obesity. Conclusion. The analysis shows that, in the case of the modern indigenous northerners, nutritional and genetic risks of metabolic disorders accumulate.

Association among nocturnal enuresis, body weight and obstructive sleep apnea in children of south Italy: an observational study.

BACKGROUND: To evaluate the rate of nocturnal enuresis (NE), body weight and obstructive sleep apnea in children 5 to 10 years of age in South Italy and the possible association among these disorders. METHODS: We have administered 1100 validated questionnaires, in Italian language, to parents and we have analyzed data with a logistic regression. RESULTS: Forty-two percent of children had a BMI≥85th (group 1) vs 58.0% normal weight children at the same age (group 2). There is a higher number of overweight males compared to females without statistically differences. In group 1 there was a higher number of children with NE and obstructive sleep disorders and some children present with the association among these three disorders. CONCLUSIONS: There are no statistically differences between two study groups for the association body weight-NE, body weight-NE-obstructive sleep disorders.

[Consumption of free sugars and excess weight in infants. A longitudinal study]. / Ingesta de azúcares libres y exceso de peso en edades tempranas. Estudio longitudinal.

INTRODUCTION: The consumption of free sugars has been related to excess weight, with the WHO recommending an intake of <10% of total energy. The aim of this study is to assess the association between the consumption of free sugars at 12 months and the risk of excess weight at 30 months in healthy children. MATERIAL AND METHODS: A longitudinal study was conducted on 81 children followed-up from birth to 30 months. A record was made of the clinical history and anthropometry, at birth, and at 12 and 30 months. Weight status was classified as with or without excess weight, according to WHO values. At 12 months, the intake of energy and nutrients was analysed by differentiating the intake of free and natural sugars. Multivariate analyses adjusted for the main confounding variables were performed. RESULTS: Free sugars were consumed by 40.4% of the 12-month-old children, being higher than that recommended, and being significantly higher in children with excess weight at 30 months (60.9%). The higher intake of free sugars at 12 months is associated with an increased risk of excess weight at 30 months (OR: 1.130, 95% CI: 1.032-1.238). CONCLUSIONS: The consumption of free sugars is much higher than that recommended in 12-month-old infants. This high intake could be a risk factor for excess weight, even at early ages.

Activity of the antioxidant enzyme paraoxonase in Argentinean children living at high altitude.

BACKGROUND: Children living at high altitude in San Antonio de los Cobres (SAC), Argentina, were shown to have lower high-density lipoprotein cholesterol (HDL-C) levels than Buenos Aires (BA) children. HDL antioxidant capacity is mainly attributed to paraoxonase1 (PON1). OBJECTIVE: To compare PON1 activity in indigenous SAC vs. BA children. METHODS: A cross-sectional study compared 158 SAC vs. 97 BA children (6-16 years). Anthropometric data and lipoprotein profile were measured. PON1 was evaluated employing paraoxon (PON) and phenylacetate (ARE) activity. RESULTS: The prevalence of overweight/obesity was lower in SAC than in BA children (18.3 vs. 30.9%). Triglycerides (1.34 vs. 0.90 mmol/l), apo B (0.84 vs.0.72 g/l), apo A-I (1.33 vs. 1.27 g/l), and ARE activity (100 vs. 90 µmol/ml/min) were higher, while HDL-C (1.16 vs. 1.32 mmol/l) and PON activity (170 vs. 203 nmol/ml/min) were lower in SAC than in BA. Separate multiple linear regression analyses showed that SAC children had significantly higher triglyceride (Beta -0.38), apo B (Beta -0.34), and ARE (Beta -0.36) plus lower HDL-C (Beta 0.33) and PON (Beta 0.25) compared with BA; adjusted for age, gender, and BMI. CONCLUSION: SAC showed an unfavorable lipoprotein profile, lower PON and higher ARE activities compared with BA children, suggesting the presence of altered HDL metabolism and antioxidant capacity.

Lipoprotein-associated phospholipase A2 activity in obese adolescents with and without type 2 diabetes.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) was identified as a strong predictor for cardiovascular events. Furthermore, it is highly associated with obesity. The role of Lp-PLA2 in diabetes mellitus is controversial and analyses, especially in adolescents with type 2 diabetes (T2D), are missing. Therefore, we compared Lp-PLA2 activity between two obese age-, sex-, and BMI-matched cohorts of adolescents with and without T2D. Relationships between Lp-PLA2 activity and age, BMI, hemoglobin A1c, lipids, and adipokines were evaluated. Lp-PLA2 activity was analyzed in serum of 72 obese adolescents without T2D (mean age 15.2 ± 1.6 years) and in 65 obese adolescents with T2D (mean age 15.5 ± 1.8 years). Clinical data were obtained from the Diabetes-Patienten-Verlaufsdokumentation (DPV) registry. Surprisingly, obese adolescents with T2D had lower levels of Lp-PLA2 activity than obese children without T2D (160.2 ± 45.0 versus 180.9 ± 35.6 nmol/min/ml, p = 0.003), but this decrease could only be detected in male (158.8 ± 45.3 versus 190.8 ± 31.3 nmol/min/ml, p < 0.001) and not in female adolescents (162.1 ± 45.5 versus 167.7 ± 37.1 nmol/min/ml, p = 0.60). In multiple linear regression analysis, differences in Lp-PLA2 activity between cohorts remained large and significant (ß-coefficient: -31.60, 95% confidence interval [-49.27;-13.93], p < 0.001). Furthermore, Lp-PLA2 activity was positively associated with BMI (ß-coefficient: 2.04 [0.68;3.40], p = 0.004) and negatively associated with the adipokines leptin (ß-coefficient: -0.53 [-0.89;-0.17], p = 0.004) and adiponectin (ß-coefficient: -3.06, [-5.63;-0.48], p = 0.02). Elevated mean glucose concentrations in adolescents with T2D were not associated with an increase but with a decrease of Lp-PLA2 activity. Hence, in young patients with T2D the Lp-PLA2 activity as a risk predictor for cardiovascular events needs further investigation.

Calorically restricted diets decrease PCSK9 in overweight adolescents.

BACKGROUND AND AIMS: Nutritional therapy is the first line approach to treatment of hyperlipidemia in childhood. Proprotein convertase subtilisin kexin type 9 (PCSK9) is a key regulator of plasma cholesterol levels and a target of novel lipid-lowering pharmacotherapies. We examined the effects of an intensive nutritional intervention on PCSK9 levels in overweight adolescents with cardiovascular disease (CVD) risk factors. METHODS AND RESULTS: Twenty seven obese and overweight adolescents with CVD risk factors were assigned to either a low fat or low glycemic load diet. During an 8-week "Intensive Phase," assigned meals were delivered to the home, and all participants received weekly in-person home nutrition counseling and phone calls. The subjects then underwent a 4-month "Maintenance Phase" without food provision and with no in-person contact. Anthropometric measurements, laboratory data, and serum PCSK9 protein levels were measured at baseline, 8 weeks, and 6 months. PCSK9 decreased by 16.5% at 8 weeks (201.2 ± 56.3 vs 165.6 ± 58.4 ng/mL; p < 0.001); PCSK9 levels returned to baseline levels at 6 months, after the Maintenance Phase. Change in PCSK9 was associated with change in fasting insulin, HOMA-IR, and AUC insulin, independent of weight loss. CONCLUSIONS: PCSK9 decreased in youth participating in an intensive dietary intervention. Change in HOMA-IR was associated with change in PCSK9, independent of weight loss, suggesting an important relationship with insulin sensitivity. ClinicalTrials.gov Identifier: NCT01080339.

Dietary fat intake modifies the influence of the FTO rs9939609 polymorphism on adiposity in adolescents: The HELENA cross-sectional study.

BACKGROUND AND AIMS: The fat mass and obesity associated gene (FTO) has been associated with obesity and dietary intake. The aims were: (i) To assess whether energy and macronutrient intakes were different across the FTOrs9939609 genotypes in adolescents, and (ii) to explore whether dietary fat intake modified the association of the rs9939609 polymorphism with adiposity. METHODS AND RESULTS: The FTOrs9939609 polymorphism was genotyped in 652 adolescents (53% females, 14.8 ± 1.2 years, TT = 246, TA = 296, AA = 110). Energy and macronutrient intake were assessed by two non-consecutive 24 h-recalls. Weight, height, waist circumference and skinfold thicknesses were measured and body fat percent was calculated. Energy and macronutrient intake were similar across the FTOrs9939609 genotypes (P > 0.2). There were significant interactions between the FTO polymorphism and fat intake on adiposity estimates (P < 0.05). In adolescents whose fat intake was below 30% (N = 203), the A allele of rs9939609 was not associated with adiposity indices. In contrast, in adolescents whose fat intake was between 30% and 35% of energy (N = 190), the rs9939609 polymorphism was associated with a 1.9% higher body fat per risk allele (95%CI: 0.39, 3.33; P < 0.05), and in those whose fat intake was higher than 35% (N = 259), it was associated with a 2.8% higher body fat per risk allele (95%CI: 1.27, 4.43; P < 0.001). CONCLUSIONS: These findings support the concept that the deleterious effect of the FTOrs9939609 polymorphism on adiposity is exacerbated in adolescents consuming high fat diets. In contrast, the consumption of low fat diets (<30% of energy) may attenuate the genetic predisposition to obesity in risk allele carriers.

Weight Loss Mediated Reduction in Xanthine Oxidase Activity and Uric Acid Clearance in Adolescents with Severe Obesity.

BACKGROUND: Increased xanthine oxidase (XO) activity and uric acid levels are known to be associated with obesity and hypertension; however, it is not known if obesity is directly responsible for these associations in youth. This study investigated the effect of weight loss on XO activity, uric acid, and their relationship to blood pressure change in obese youth to provide greater insight on how obesity increases cardiovascular risk. METHODS: This was an ancillary study in which 16 adolescents (mean age 15 ± 2 years) received meal replacement therapy over a period of four weeks. Outcomes measured at baseline and after intervention included weight, blood pressure, XO activity, plasma uric acid, uric acid clearance, and creatinine clearance. RESULTS: After the meal replacement intervention, participants experienced reductions in body weight (109.2 ± 16 kg vs. 105.2 ± 14 kg, p < 0.0001) and BMI (38.7 ± 4 kg vs. 37.4 ± 3 kg, p < 0.0001). Plasma XO activity was reduced by 9.8% (p = 0.016). Uric acid clearance was decreased by 39% (p = 0.006). SBP (systolic blood pressure) and plasma uric acid concentrations were reduced but did not achieve statistical significance (p = 0.34 and 0.38, respectively). DBP (diastolic blood pressure) was unchanged (p = 0.86). No significant relationships were found between changes in blood pressure and changes in either XO activity or plasma uric acid levels. CONCLUSION: Weight loss led to decreases in uric acid production by lowering XO activity and decreases in uric acid clearance by reducing glomerular filtration (GF) and increasing reabsorption. Changes in XO activity and uric acid levels did not correlate with changes in blood pressure.

The Ontogeny and Population Variability of Human Hepatic NADPH Dehydrogenase Quinone Oxido-Reductase 1 (NQO1).

The NADPH dehydrogenase quinone oxido-reductase 1 (NQO1) enzyme is an antioxidant and metabolic enzyme that performs two electron reduction of quinones and other chemicals. Based on the physiologic role(s) of NQO1, we hypothesized that expression and activity of this enzyme would vary with age and other demographic variables. Cytosols from 117 archived human livers were investigated for changes in NQO1 with age, sex, obesity, and ethnicity. Protein expression but not activity of NQO1 was weakly negatively correlated with age (Spearman r = -0.2, P = 0.03). No sex differences were observed for either protein expression or activity and for ethnicity; Caucasians had greater NQO1 activity than Asians (P < 0.05). Overweight children had statistically significantly higher NQO1 activity as compared with ideal weight children (P < 0.05) although this difference was not observed in adults. These findings establish that NQO1 is approximately as active in children as adults. However, modeled NQO1 clearance (both allometric and physiologically based pharmacokinetics) predicted maturation at 23 to 26 years. This is almost certainly an overestimate, with error in the model resulting from a small sample size and inability to scale for age-related changes in hepatic cellularity and/or cytosolic protein content, and indicates a delay in reaching maximum clearance through the NQO1 pathway that is affected by physiologic development as much, or more than, biochemical development. Obesity may increase hepatic NQO1 activity in children, which is likely a protective mechanism in oxidative stress, but may also have significant implications for drug and chemical disposition in obese children.

Impact of LPL gene rs283 polymorphism on exercise-induced changes in metabolism of obese adolescents and the regulatory mechanisms behind it.

NEW FINDINGS: What is the central question of this study? We investigated whether the LPL gene rs283 polymorphism affects exercise-induced changes in body composition and lipid and glucose metabolism in obese adolescents and whether it is functional. What is the main finding and its importance? Chinese obese adolescents of Han nationality with the GG genotype of the rs283 polymorphism were more sensitive to exercise-induced reduction of the body fat percentage, insulin resistance and plasma triglyceride levels. The G allele can significantly increase reporter gene expression level, which may be the molecular reason for the difference in exercise-induced parameter changes among obese adolescents. The aim of this investigation was to explore the association between the rs283 polymorphism located in the lipoprotein lipase (LPL) gene and exercise-induced changes in body composition and lipid and glucose metabolism in obese adolescents and to probe into the molecular regulatory mechanisms. Fifty-five obese adolescents of Han nationality underwent aerobic training for 4 weeks. Body composition and lipid and glucose metabolic parameters were tested before and after the training. The rs283 polymorphism was genotyped by PCR-restriction fragment length polymorphism, and association analysis with the weight-reducing effect was performed. The regulatory mechanisms of the rs283 polymorphism were explored through the dual-luciferase reporter assay. Exercise-induced change rates were as follows: the change in body fat percentage of GG genotype groups was 3.37 ± 1.60, significantly higher than that of GA genotype groups (2.09 ± 1.53, P < 0.01); the change in the homeostasis model assessment of insulin resistance was 0.52 ± 0.13, obviously higher than that of GA genotype groups (0.44 ± 0.10, P < 0.05); and the change in triglyceride was 51.91 ± 6.56, much higher than that of GA genotype groups (47.06 ± 5.36, P < 0.01). The relative luciferase activity of the reporter gene in recombinant vector carrying the G allele was 2.67 ± 0.22, markedly higher than that in recombinant vector carrying the A allele (1.63 ± 0.03, P < 0.01). Chinese obese adolescents of Han nationality with GG genotype of the rs283 polymorphism were more sensitive to exercise-induced parameter changes. The G allele can improve reporter gene expression level, indicating the effects of rs283 on gene expression.

Serum paraoxonase/arylesterase activity and oxidative stress status in children with metabolic syndrome.

OBJECTIVE: This study aimed to measure paraoxonase/arylesterase activities and to evaluate the total oxidant and antioxidant capacities in obese children and in children with metabolic syndrome (MetS). METHODS: A total of 151 children of comparable ages (13.23±1.96 years, 13.45±1.85 years and 13.95±1.31 years) were enrolled in the study. Forty of these were children with MetS, 55 were obese and 56 were healthy controls. Diagnosis of the MetS was made according to International Diabetes Federation criteria. Paraoxonase/arylesterase activities were evaluated by using paraoxon and phenylacetate substrates. Total oxidant status (TOS) and total antioxidant status (TAS) were measured and oxidative stress index (OSI) was estimated by calculation. RESULTS: High levels of paraoxonase were detected in the obese group, whereas high levels of arylesterase were detected in both MetS and obese groups. Higher values for TOS, TAS and OSI were found in the MetS group (p<0.05). CONCLUSION: Higher values of mean TOS and OSI in the MetS group than those in the control groups indicate that these parameters may be indicators of future risks such as atherosclerosis in patients with MetS.

Impaired paraoxonase-1 status in obese children. Relationships with insulin resistance and metabolic syndrome.

OBJECTIVES: To investigate the relationships between serum paraoxonase-1 (PON1), insulin resistance, and metabolic syndrome (MetS) in childhood obesity. DESIGN AND METHODS: We studied 110 obese children and 36 non-obese children with a similar gender and age distribution. We measured serum PON1 activity against 5-thiobutyl butyrolactone (TBBLase) and against paraoxon (paraoxonase). PON1 concentration was measured separately as were the levels of several standard metabolic variables. The homeostasis model assessment (HOMA) index was calculated as an estimate of insulin resistance. RESULTS: TBBLase was significantly decreased in obese children (P=0.008), while paraoxonase activity and PON1 concentrations showed non-significant trends towards decrease and increase, respectively (P=0.054 and P=0.060). TBBLase and paraoxonase specific activities were significantly decreased (P=0.004 and P=0.018, respectively). TBBLase specific activity was inversely associated with BMI, percentage body fat, insulin, HOMA, triglycerides, and C-reactive protein, and directly associated with HDL-cholesterol. Paraoxonase specific activity showed similar associations with BMI, percentage fat, HDL-cholesterol, and C-reactive protein. Obese children with MetS had lower TBBLase activities than obese children without MetS (P=0.018). Linear regression analyses showed that TBBLase was independently associated with HDL-cholesterol, BMI, percentage body fat and PON155 polymorphism, but paraoxonase activity was associated only with PON1192 polymorphism. CONCLUSIONS: Our results suggest that PON1 may play a role in the onset and development of metabolic alterations in childhood obesity leading to diabetes and cardiovascular disease later in life. However, being derived from statistical association study, this finding cannot be seen as showing cause-effect.

Paraoxonase 1 activities and genetic variation in childhood obesity.

Changes in paraoxonase 1 (PON1) activities have been observed in a variety of diseases involving oxidative stress, such as CVD. However, its role in obesity has not been fully established. In the present study, we aimed (1) to genotype sixteen PON1 SNP, (2) to measure serum PON1 activities and (3) to correlate these findings with the incidence of childhood obesity and related traits. We conducted a case-control study of 189 normal-weight and 179 obese prepubertal children, and we measured four different PON1 activities: lactonase; paraoxonase; arylesterase; diazoxonase. Although none of these activities was significantly different between the obese and normal-weight children, lactonase activity was found to be positively correlated with HDL-cholesterol and ApoA1 levels and negatively correlated with myeloperoxidase and fatty acid-binding protein 4 levels. Among the sixteen genotyped PON1 SNP, only the intronic SNP rs854566 exhibited a significant association with obesity (OR 0·61, 95 % CI 0·41, 0·91; P= 0·016). This genetic variant was also associated with increased diazoxonase, lactonase and arylesterase activities and decreased paraoxonase activity. Other genetic variants exhibited different association patterns with serum activities based on their location within the PON1 gene, and SNP that were located within the promoter were strongly associated with lactonase, arylesterase and diazoxonase activities. The functional variant Q192R exhibited the greatest effect on paraoxonase activity (P= 5·88 × 10(-42)). In conclusion, SNP rs854566 was negatively associated with childhood obesity and with increased serum PON1 activities in prepubertal children. We determined that lactonase is a reliable indicator of PON1 activities and should be included in future studies of PON1 function.

Ghrelin-leptin network influences serum chitinase 3-like protein 1 (YKL-40) levels in obese prepubertal children.

OBJECTIVE: This study aimed to investigate any possible interactions between hormonal regulators of weight gain and markers of subclinical inflammation in childhood obesity. Forty-one obese prepubertal children and 41 age- and gender-matched lean controls were included. Children were classified as obese or non-obese according to international age- and gender-specific body mass index (BMI) cutoff points defined by the International Obesity Task Force to define childhood obesity. Anthropometric measurements, serum insulin, chitinase 3-like protein (YKL-40), ghrelin and leptin levels as well as plasma glucose in the fasting state were determined. RESULTS: Obese children as compared with controls had higher YKL-40 (50.7±15.2 vs 41.0±10.5 ng/ml, p=0.003), higher leptin (33.8±16.0 vs 9.7±7.5 ng/ml, p<0.001) and lower ghrelin serum levels (871.4±368.0 vs 1417.6±387.3 pg/ml, p<0.001). The obese children with ghrelin levels above median (43.8±10.2 ng/ml) as compared to those with ghrelin below median (57.2±16.6 ng/ml) presented lower serum YKL-40 levels (p=0.009), indicating more severe inflammation with lower levels of ghrelin. By contrast, although the obese children with leptin levels above median (49.7±16.3 ng/ml) presented lower serum YKL-40 levels as compared to those with leptin levels below median (51.6±14.6 ng/ml), this difference did not reach the level of statistical significance (p=0.726). Moreover, serum YKL-40 levels were significantly correlated with ghrelin (r=-0.359, p=0.014) but not with leptin levels (r=0.169, p=0.261). A significant negative correlation between ghrelin and leptin levels was also found (r=-0.276, p=0.041). These findings remained unchanged for obese, when analyses were done separately, whereas the significance of correlations was lost for non-obese subjects. CONCLUSIONS: Ghrelin-leptin network had an impact on serum YKL-40 levels in obese prepubertal children; upregulation of YKL-40 secretion seems to be a consequence of reduced ghrelin rather than elevated leptin concentrations.