Beatriz Cano

Leptin and adiponectin levels in pubertal children: relationship with anthropometric variables and body composition.

Abstract Background: Adipocytokines play an important role in controlling energy homeostasis, and in various metabolic processes related to obesity. The aim of this study was to describe serum leptin and adiponectin concentrations in a sample of pubertal Spanish children and to evaluate their association with anthropometric parameters and body composition. Methods: The study included 833 pubertal boys and girls. Serum leptin and adiponectin concentrations were determined by ELISA. Results: Leptin concentrations were significantly higher (p<0.0001) in obese or overweight (OW) children compared with children with normal weight (NW). Adiponectin was significantly lower (p<0.01) in obese or OW girls compared with girls of NW, although these findings were not the same for boys. Weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), and waist to hip ratio were significantly correlated (p<0.01) with leptin concentrations in both genders. Correlation of leptin with fat mass and % fat mass was strong, particularly in boys. The association of adiponectin concentrations with anthropometric variables was weaker in both genders. No significant correlations were found between adiponectin concentrations and fat mass or % fat mass. Conclusions: In summary, our study showed that, in pubertal children, leptin is related to weight, BMI, WC and HC and correlates even more strongly with % fat mass. However, adiponectin was weakly related to anthropometric variables and was not correlated with body fat. Clin Chem Lab Med 2010;48:707–11.

Sex hormone-binding globulin and lipid profile in pubertal children.

Men and women have different lipid profiles throughout life, related to changes in sex hormones; and this has been associated with sex-related differences in the prevalence of coronary heart disease. The influence of sex hormone changes during puberty on the lipid profile has been reported, but levels of sex hormone-binding globulin (SHBG) (the specific plasma binding protein of sex hormones) have not been evaluated even though its regulatory role might be crucial. The aim of this study was to analyze the relationship between sex hormones and SHBG and changes in plasma lipid levels during puberty. Our population-based sample included 370 healthy schoolchildren (175 male and 195 female), ranging from 12 to 15 years old. High-density lipoprotein cholesterol (HDL-C) levels were significantly lower in 15-year-olds than in younger boys, and apolipoprotein (apo) A-I levels steeply decreased across the studied age groups. Parallel to these changes, testosterone levels increased whereas SHBG decreased as age increases in boys. In girls, no significant differences were observed in these variables among the age groups. Testosterone and SHBG were highly correlated with anthropometric variables. Sex hormone-binding globulin was negatively associated with triglycerides (TG) in both sexes, remaining statistically significant after further adjustment for age and body mass index (BMI) in girls. Sex hormone-binding globulin was the only predictive variable for HDL-C and TG in multiple linear regression analysis, after adjustment by BMI, in both sexes, accounting for 10% of the variance of HDL-C in boys and for around 5% of the variance of TG in both sexes. In boys, testosterone and SHBG remained significantly correlated to apo A-I levels, even after adjusting for age and BMI, and were the most important predictive variables for apo A-I in multiple linear regression analysis. In conclusion, SHBG levels are related to a decrease in HDL-C and apo A-I levels during puberty in boys and to a decrease in TG levels during puberty in both sexes.

Relationship of adiponectin with metabolic syndrome components in pubertal children

OBJECTIVE Adiponectin is an adipose tissue-derived adipocytokine which appears in decreased concentrations in obese patients and in several processes related to cardiovascular disease, such as type 2 diabetes or metabolic syndrome. The aim of this study was to analyze the relationship between adiponectin and components of metabolic syndrome (lipid profile, blood pressure, insulin and insulin resistance) in pubertal Spanish children. METHODS The population-based sample included 810 healthy children (382 boys and 428 girls) 12-16 years of age. Anthropometric parameters and blood pressure were measured. Lipid levels were determined by standard methods, and insulin and adiponectin concentrations were measured by ELISA. Insulin resistance index was assessed by HOMA-IR. RESULTS Adiponectin levels were negatively correlated with insulin and HOMA in both boys and girls, and remained significant after adjustment for BMI z-score in girls. After this adjustment, adiponectin maintained a positive correlation with HDL-cholesterol and HDL-phospholipids in both genders, and correlated with triglycerides in girls. Multiple linear regression analysis showed that, after adjustment for BMI z-score, adiponectin accounted for 15.8% of the variation of HDL-cholesterol in girls and for 5% of its variation in boys; meanwhile, it accounted for 15.8% and 12.7% of the variation of HDL-phospholipids in girls and boys, respectively. CONCLUSIONS Adiponectin levels in 12- to 16-year-old children appear to be more strongly related to better lipid profile and insulin sensitivity in girls than in boys. Our study shows, for the first time to our knowledge, a significant positive correlation between adiponectin and HDL-phospholipids in pubertal children.

Cholesterol and saturated fat intake determine the effect of polymorphisms at ABCG5/ABCG8 genes on lipid levels in children

Purpose: Analysis of mutations in genes of the cholesterol metabolic pathway has not completely explained the interindividual variability of blood cholesterol concentrations attributed to gene–nutrient interactions. Thus, we analyzed polymorphisms in the ABCG5 and ABCG8 genes, involved in the regulation of intestinal cholesterol absorption, with special interest in a potential interaction with diet to determine lipid levels.Methods: The polymorphisms ABCG5 C1950G (Gln604Glu) and ABCG8 C1895T (Ala640Val) were determined by polymerase chain reaction and restriction analysis in 1227 healthy school children, aged 6 to 8 years.Results: No significant differences were found in blood lipid levels between subjects with different genotypes of the two analyzed polymorphisms. However, important differences appeared when separating subjects by their different lipid intake. The presence of the ABCG8 C1895T and ABCG5 C1950G polymorphisms was associated with different plasma total cholesterol, low-density lipoprotein cholesterol complex, and apolipoprotein B levels only in low-cholesterol consumers (significantly for the C1895T polymorphism), and among children within the lower tertile of saturated fat intake (significantly for the C1950G polymorphism).Conclusion: Polymorphisms at the half-transporter ABCG5 and ABCG8 genes affect blood cholesterol concentrations in prepubertal children by influencing dietary responsiveness. This highly significant gene–nutrient interaction could explain the great individual differences in the plasma lipid response to cholesterol and fat intake.

Plasma homocysteine in adolescents depends on the interaction between methylenetetrahydrofolate reductase genotype, lipids and folate: a seroepidemiological study

BackgroundMany publications link high homocysteine levels to cardiovascular disease. In Spain there is little information on the prevalence of hyperhomocysteinaemia and associated vitamin factors among the general population, and less still among children. Cardiovascular risk factors in the childhood population may be related to the appearance of cardiovascular disease at adult age. The aim of this study is to establish a definition of hyperhomocysteinaemia in adolescents and to analyze the influence of vitamin and metabolic factors in homocysteine levels in this population group.MethodsDescriptive, cross-sectional epidemiological study to estimate serum homocysteine, vitamin B12 and folate levels, as well as plasma total, HDL- and LDL- cholesterol in a schoolgoing population aged 13 to 17 years in Madrid, Spain.Spearman correlation analysis was performed to ascertain quantitative comparison, Pearsons χ2 test (frequency < 5, Fisher) was used for comparison of prevalences, Mann-Whitney U and Kruskal-Wallis test were used for comparison of means and Bonferroni correction was used for post-hoc tests. A multivariate logistic regression model was performed in the multivariate analysis.ResultsBased on the classic values for definition of hyperhomocysteinaemia in adults, prevalence of hyperhomocysteinaemia in the study population was: 1.26% for 15 μmol/L; and 2.52% for 12 μmol/L.Deficits in HDL cholesterol and serum folate levels yielded adjusted Odds Ratios (OR) for hyperhomocysteinemia of 2.786, 95% CI (1.089-7.126), and 5.140, 95% CI (2.347-11.256) respectively. Mutation of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype also raises the risk of hyperhomocysteinaemia (CC→CT: OR = 2.362; 95% CI (1.107-5.042) CC→TT: OR = 6.124, 95% CI (2.301-16.303))ConclusionA good definition of hyperhomocysteinaemia in adolescents is the 90th percentile, equivalent to 8.23 μmol/L. Risk factors for hyperhomocysteinaemia are cHDL and folate deficiency, and the MTHFR C677T mutant genotype. No significant effect could be assessed for vitamin B12. Coexistence of all three factors increases the risk of suffering from hyperhomocysteinaemia 87-fold.

Hormone levels in 12- to 15-year-old boys and girls in Spain and their relationship with anthropometric variables.

OBJECTIVE To determine hormone levels in a population-based sample of pubertal children and evaluate their association with anthropometric parameters. METHODS Sex steroid levels were assessed using RIA and IRMA. RESULTS In boys, changes in weight and height across the period were accompanied by changes in testosterone and SHBG. In girls, anthropometric variables did not change and were not correlated with estradiol. CONCLUSIONS We observed an association between hormone levels and anthropometric changes when active growth associated with puberty was taking place.

The serum levels of the EGF‐like homeotic protein dlk1 correlate with different metabolic parameters in two hormonally different children populations in Spain

Background  The Dlk1 gene encodes for dlk1, a transmembrane protein belonging to the EGF‐like repeat‐containing family. Dlk1 has been shown to act as a regulator of adipogenesis. Fc‐dlk1 transgenic mice show a decrease in adipose tissue and glucose tolerance, hypertriglyceridaemia and lower insulin sensitivity. Dlk1‐deficient mice show growth retardation, increased serum lipid metabolites and develop obesity. These data advocate for a role of dlk1 in the maintenance of lipid homeostasis, and suggest that dlk1 levels may influence the development of cardiovascular disease.

Variations in APOE genotype distribution in children from areas with different adult cardiovascular disease mortality in Spain.

Abstract We investigate whether a varying distribution of the APOE genotype could help explain regional differences in ischemic heart disease (IHD) mortality in Spain. APOE genotypes were examined by PCR in 1,274 randomly selected healthy children from four Spanish regions with different adult IHD mortality rates (northwest and central Spain with low rates and southeast and southern Spain with high rates). In the population as a whole the prevalence of the higher risk APOE*3/*4 genotype is 16.8% and the prevalence of the APOE*4 allele is 10.1%. In northwest Spain the frequencies of the APOE*3/*4 genotype (12.9%) and of the APOE*4 allele (8.3%) are smaller than in the other regions. The southeast region shows statistically higher frequencies of the APOE*3/*4 genotype (22.5%) and of the APOE*4 allele (13.2%) than in the other regions or in the group as a whole. We can conclude that Spain is not homogeneous in terms of APOE genotype distribution. Although the prevalence of the APOE*4 allele is generally low, there are areas with higher prevalence of the APOE*4 allele and a higher incidence of adult IHD mortality. This allows us to conclude that in Spain this genetic determinant can be associated with IHD mortality in relatively isolated populations.

Genetic determinants of plasma HDL-cholesterol levels in prepubertal children

INTRODUCTION Genetic determinants have been related to variation of high-density lipoprotein cholesterol (HDL-C) levels, but the extension of this association remains controversial. In our study, we analyzed the contribution of several polymorphisms on HDL-C-related genes to variation of plasma HDL-C in prepubertal children. METHODS We studied 1269 (641 males and 628 females) 6-8 years old healthy children, who participated in a cross-sectional study examining cardiovascular risk factors in Spain. Common genetic variants in the apolipoprotein AI, apolipoprotein AII, cholesteryl ester transfer protein (CETP), hepatic lipase, ATP-binding cassette transporter A1, and paraoxonase genes were determined by PCR. RESULTS CETP TaqI B2 carrier girls had significantly higher HDL-C levels than B1B1 girls. B2B2 boys had significantly higher (p<0.001) HDL-C than B1B1and B1B2 boys. In linear regression analysis, CETP TaqIB appears as the main predictor of HDL-C plasma levels, accounting for 4.5% and 1.8% of HDL-C variation in girls and boys respectively. CONCLUSIONS Our data showed that among the studied polymorphisms only the CETP TaqIB polymorphism contributes to the variation in HDL-C levels in prepubertal children, particularly in girls, but overall these polymorphisms explain a small part of the variation of HDL-C plasma levels at this age.

Dehydroepiandrosterone Sulfate and High-density Lipoprotein-cholesterol Levels in Overweight Children

Objective: The association of childhood overweight with cardiovascular risk factors seems to change by sex and age, which may indicate that hormonal status could be the cause of this different association. In this study, we analyzed the relationship of dehydroepiandrosterone sulfate (DHEA‐S) with the alterations associated with overweight by analyzing the influence of this hormone in the differences found in biochemical variables between normal‐weight and overweight prepubertal children.