Serum leptin levels in normal children: relationship to age, gender, body mass index, pituitary-gonadal hormones, and pubertal stage

Leptin resistance in children with in utero exposure to maternal obesity and gestational diabetes

BACKGROUND

Leptin resistance occurs with obesity, but it is unknown if individuals at risk for obesity develop leptin resistance prior to obesity.

OBJECTIVE

Investigate whether leptin resistance is independent of weight status in children at risk for obesity due to intrauterine exposure to maternal obesity or gestational diabetes mellitus (GDM).

METHODS

Mother-child dyads (N = 179) were grouped by maternal pregnancy weight and GDM status: (1) normal weight, no GDM; (2) overweight/obesity, no GDM; (3) overweight/obesity with GDM. Children (4-10 years) were further stratified by current body mass index (BMI) <85th or ≥85th percentile. Leptin resistance of children and mothers was calculated as fasting leptin/fat mass index. Two-way ANOVA was used to assess whether leptin concentrations and leptin resistance differed by current weight status or in utero exposure group, after adjusting for race, sex and Tanner stage.

RESULTS

Children with a BMI ≥85th percentile had more leptin resistance than those with a BMI <85th percentile (p < 0.001), but leptin resistance did not differ by in utero exposure. Similarly, leptin resistance in women was associated with weight status and not prior GDM.

CONCLUSIONS

Results suggest that leptin concentrations are associated with obesity but not risk for obesity based on in utero exposure to maternal obesity or GDM.

Tensiomyography: from muscle assessment to talent identification tool

Introduction: Tensiomyography (TMG) is a non-invasive and cost-effective tool that is gaining popularity in fields such as sports science, physical therapy, and medicine. In this narrative review, we examine the different applications of TMG and its strengths and limitations, including its use as a tool for sport talent identification and development. Methods: In the course of crafting this narrative review, an exhaustive literature search was carried out. Our exploration spanned several renowned scientific databases, such as PubMed, Scopus, Web of Science, and ResearchGate. The materials we sourced for our review included a broad spectrum of both experimental and non-experimental articles, all focusing on TMG. The experimental articles featured varied research designs including randomized controlled trials, quasi-experiments, as well as pre-post studies. As for the non-experimental articles, they encompassed a mix of case-control, cross-sectional, and cohort studies. Importantly, all articles included in our review were written in English and had been published in peer-reviewed journals. The assortment of studies considered provided a holistic view of the existing body of knowledge on TMG, and formed the basis of our comprehensive narrative review. Results: A total of 34 studies were included in the review, organized into three sections: 1) assessing muscle contractile properties of young athletes, 2) using TMG in the talent identification and development process and 3) Future research and perspectives. According to data presented here, the most consistent TMG parameters for determining muscle contractile properties are radial muscle belly displacement, contraction time, and delay time. Biopsy findings from the vastus lateralis (VL) confirmed TMG as a valid tool for estimating the ratio of myosin heavy chain (%MHC-I). Conclusion: TMGs ability to estimate the ratio of %MHC-I has the potential to aid in the selection of athletes with the muscle characteristics best suited for a particular sport, eliminating the need for more invasive procedures. However, more research is warranted to fully understand TMG's potential and its reliability when used with young athletes. Importantly, the use of TMG technology in this process can positively impact health status, reducing the frequency and severity of injuries and the duration of recovery, and subsequently can reduce drop out rates among youth athletes. Future studies should look at twin youth athletes, as a model capable of discriminating between the influence of hereditary factors vs. environmental factors, in therms of muscle contractility and TMG's potential for instance.

Sexual dimorphism of leptin and adiposity in children between 0 and 10 years: a systematic review and meta-analysis

BACKGROUND

Differences in adolescents and adults by sex in blood levels of leptin and adiposity have been described; however, it is not yet clear if these differences arise from the prepubertal stage in subjects with a normal-weight. Therefore, we examine whether there are differences by sex in levels of blood leptin and adiposity in children with a normal-weight between 0 and 10 years old.

METHODS

Search strategy: eligible studies were obtained from three electronic databases (Ovid, Embase and LILACS) and contact with experts.

SELECTION CRITERIA

healthy children up to 10 years of age with normal-weight according to age.

DATA COLLECTION AND ANALYSES

data were extracted by four independent reviewers using a predesigned data collection form. For the analysis, we stratified according to age groups (newborns, 0.25-0.5 years, 3-5.9 years, 6-7.9 years, 8-10 years). The statistical analysis was performed in the R program.

RESULTS

Of the initially identified 13,712 records, 21 were selected in the systematic review and meta-analysis. The sex was associated with the overall effect on blood leptin (pooled MD = 1.72 ng/mL, 95% CI: 1.25-2.19) and body fat percentage (pooled MD = 3.43%, 95% CI: 2.53-4.33), being both higher in girls. This finding was consistent in the majority of age groups.

CONCLUSION

The results of our meta-analyses support the sexual dimorphism in circulating blood leptin and body fat percentage between girls and boys with normal-weight from prepuberty.

Differences in Cardiopulmonary Fitness Between Boy and Girls With Repaired Tetralogy of Fallot

OBJECTIVE

Many studies have demonstrated that patients with repaired tetralogy of Fallot (rTOF) have generally poorer cardiopulmonary fitness (CPF). However, little is known about how the disease results in different CPF in each sex. Therefore, this study aimed to investigate whether sex (and gender) differences affect CPF in children and adolescents with rTOF.

METHODS

This retrospective study recruited adolescents and children (aged 10-18) with rTOF following an acute stage of tetralogy of Fallot (TOF) who received cardiopulmonary exercise testing (CPET) in the past 10 years. CPF was determined by symptom-limited CPET with a treadmill under ramped Bruce protocol. Boys and girls were categorized into groups based on body mass index (BMI) and fat mass index (FMI). The BMI was grouped by Taiwanese obesity cutoff points. The FMI was categorized by the body fat percentage. Excess adiposity was defined as (1) "overweight" and "obese" by BMI and (2) greater than the sex- and age-specific 75th percentile of whole subjects by FMI.

RESULTS

A total of 185 participants (104 boys and 81 girls) with rTOF were recruited for the final analysis. Within the BMI category, 76 boys and 63 girls were in the normal group, whereas 28 boys and 18 girls were in the excessive adiposity group. Within the FMI category, 77 boys and 60 girls were in the normal group, whereas 27 boys and 21 girls were in the excessive adiposity group. The analysis of the body composition of rTOF subjects showed that there was no statistically significant difference between the subgroups of the two sexes, but both showed a smaller body size than normal Taiwanese children. When comparing the CPF within different BMI and FMI groups, the children in the excessive adiposity group had significantly lower values in metabolic equivalents (MET) at anaerobic threshold, peak MET, and measured peak oxygen consumption (VO₂) to predicted peak VO₂, regardless of sex. Moreover, boys (60.90%) presented poorer CPF than girls (74.22%, p < 0.001).

CONCLUSION

In Taiwan, patients with rTOF had poorer CPF than healthy peers. This study found that girls with rTOF had better CPF than boys with rTOF. The effect of gender stereotypes on sports participation and self-efficacy might be one of the contributing factors; however, further investigations are warranted to determine the causal effect.

Leptin Is an Important Endocrine Player That Directly Activates Gonadotropic Cells in Teleost Fish, Chub Mackerel

Leptin, secreted by adipocytes, directly influences the onset of puberty in mammals. Our previous study showed that leptin stimulation could promote the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from pituitary cells in primary culture and ovarian development in chub mackerel. This study aimed to elucidate the detailed mechanism of leptin-induced effects on gonadotropin hormone-producing cells. We produced recombinant leptin using silkworm pupae and investigated the effects of leptin on FSH and LH secretion and gene expression in the primary culture of pituitary cells from chub mackerel. The presence or absence of co-expression of lepr mRNA, FSH and LH b-subunit mRNA in gonadotropic cells was examined by double-labeled in situ hybridization. The addition of leptin significantly increased the secretion and gene expression of FSH and LH from male and female pituitary cells in primary culture. In contrast, gonadotropin-releasing hormone 1 affected neither FSH secretion in cells from females nor fshb and lhb expression in cells from males and females. The expression of lepr was observed in FSH- and LH-producing cells of both males and females. The results indicate that leptin directly regulates gonadotropin synthesis and secretion and plays an important role in the induction of puberty in teleost fish.

The Association Between Dietary Inflammatory Potential and Sex Hormones in Male Children and Adolescents Aged 6-19 Years

Aims

This study aimed to assess the relationship between dietary inflammatory index (DII) and sex hormones in male children and adolescents aged 6-19 years.

Methods

We obtained data from the 2013-2016 National Health and Nutrition Examination Survey (NHANES). Male participants aged 6-19 years old with the complete data of DII and sex hormones were included. Weighted multiple regression analysis and subgroup analysis were preformed to estimate the independent relationship between DII and sex hormones.

Results

A total of 1717 male participants with the average age of 13.02 ± 3.82 years were enrolled, of whom 41.3% (n=713) were children and 58.47% (n=1004) were adolescents. In children, mean DII was 0.18 ± 1.67, with scores ranging from -4.53 to 4.08. As for adolescents, the mean DII was 0.36 ± 1.98, mean total testosterone (TT) was 376.94 ± 206.69 ng/dl overall. A negative association between DII with TT and estradiol (E2) was observed (TT: β=-11.97, P=0.0006; E2: β=-0.45, P=0.0108) in male adolescent. Subgroup analysis and interaction test results indicated that this association was similar in male adolescents with different body mass index. No statistically significant association was observed in children.

Conclusions

Pro-inflammatory diet was associated with lower TT and E2 level in male adolescent, while no association with statistical significance between them was observed in male children. However, more studies are still needed to validate the causal relationship between DII and sex hormones.

Short-term effects of gonadotropin-releasing hormone analogue treatment on leptin, ghrelin and peptide YY in girls with central precocious puberty

OBJECTIVES

To determine appetite-regulating hormone levels in girls with central precocious puberty (CPP) before and after 20 weeks of gonadotropin-releasing hormone analogue (GnRH-A) treatment.

METHODS

Eighteen newly diagnosed CPP girls were enrolled. Body composition measured by bioelectrical impedance analysis and GnRH-A test were performed with fasting serum leptin, ghrelin and peptide YY (PYY) measurements at baseline (before) and after 20 weeks of GnRH-A treatment.

RESULTS

Following GnRH-A treatment, all patients had prepubertal gonadotropin and estradiol levels. Mean (SD) fat mass index (FMI) was significantly increased from 4.5 (1.7) to 5.0 (1.8) kg/m² after treatment. Also, median (IQR) serum leptin level was significantly increased from 6.9 (4.2-8.6) to 7.4 (5.3-13.1) ng/mL. FMI had a positive correlation with serum leptin level (r=0.64, p=0.004). In contrast, no significant changes of serum ghrelin and PYY levels were observed.

CONCLUSIONS

Decreased estrogen following short-term GnRH-A treatment in CPP girls may cause an increase in appetite and consequently an elevation of FMI. Increased serum leptin may be a result of having increased FMI secondary to an increase in appetite.

The Importance of Leptin to Reproduction

A healthy nutritional state is required for all aspects of reproduction and is signaled by the adipokine leptin. Leptin acts in a relatively narrow concentration range: too much or too little will compromise fertility. The leptin signal timing is important to prepubertal development in both sexes. In the brain, leptin acts on ventral premammillary neurons which signal kisspeptin (Kiss1) neurons to stimulate gonadotropin releasing hormone (GnRH) neurons. Suppression of Kiss1 neurons occurs when agouti-related peptide neurons are activated by reduced leptin, because leptin normally suppresses these orexigenic neurons. In the pituitary, leptin stimulates production of GnRH receptors (GnRHRs) and follicle-stimulating hormone at midcycle, by activating pathways that derepress actions of the messenger ribonucleic acid translational regulatory protein Musashi. In females, rising estrogen stimulates a rise in serum leptin, which peaks at midcycle, synchronizing with nocturnal luteinizing hormone pulses. The normal range of serum leptin levels (10-20 ng/mL) along with gonadotropins and growth factors promote ovarian granulosa and theca cell functions and oocyte maturation. In males, the prepubertal rise in leptin promotes testicular development. However, a decline in leptin levels in prepubertal boys reflects inhibition of leptin secretion by rising androgens. In adult males, leptin levels are 10% to 50% of those in females, and high leptin inhibits testicular function. The obesity epidemic has elucidated leptin resistance pathways, with too much leptin in either sex leading to infertility. Under conditions of balanced nutrition, however, the secretion of leptin is timed and regulated within a narrow level range that optimizes its trophic effects.

Digenic Variants in the FGF21 Signaling Pathway Associated with Severe Insulin Resistance and Pseudoacromegaly

Insulin-mediated pseudoacromegaly (IMPA) is a rare disease of unknown etiology. Here we report a 12-year-old female with acanthosis nigricans, hirsutism, and acromegalic features characteristic of IMPA. The subject was noted to have normal growth hormone secretion, with extremely elevated insulin levels. Studies were undertaken to determine a potential genetic etiology for IMPA. The proband and her family members underwent whole exome sequencing. Functional studies were undertaken to validate the pathogenicity of candidate variant alleles. Whole exome sequencing identified monoallelic, predicted deleterious variants in genes that mediate fibroblast growth factor 21 (FGF21) signaling, FGFR1 and KLB, which were inherited in trans from each parent. FGF21 has multiple metabolic functions but no known role in human insulin resistance syndromes. Analysis of the function of the FGFR1 and KLB variants in vitro showed greatly attenuated ERK phosphorylation in response to FGF21, but not FGF2, suggesting that these variants act synergistically to inhibit endocrine FGF21 signaling but not canonical FGF2 signaling. Therefore, digenic variants in FGFR1 and KLB provide a potential explanation for the subject's severe insulin resistance and may represent a novel category of insulin resistance syndromes related to FGF21.

Circulating LEAP-2 is associated with puberty in girls

BACKGROUND/OBJECTIVES

Liver-expressed antimicrobial peptide 2 (LEAP-2) was recently identified as an endogenous non-competitive allosteric antagonist of the growth hormone secretagogue receptor 1a (GHSR1a). LEAP-2 blunts ghrelin-induced feeding and its plasma levels are modulated in response to nutritional status in humans. Despite the relevant role of ghrelin in childhood, puberty, and childhood obesity, the potential implication of LEAP-2 in these aspects remains totally unknown. We aimed to investigate the regulation of circulating plasma LEAP-2 in childhood and adolescent either lean or obese.

METHODS AND RESULTS

Plasma levels of LEAP-2 were analyzed in a cross-sectional study with lean and obese children and adolescents (n = 150). Circulating LEAP-2 levels were significantly higher in girls than in boys independently of whether they were obese or lean. In addition, LEAP-2 was significantly increased (p < 0.001) in pubertal than in prepubertal girls, while no changes were found in boys between both developmental stages. Moreover, in girls LEAP-2 was positively correlated with insulin, IGF-1, HOMA-IR and triglycerides and negatively with ghrelin. In boys, LEAP-2 was positively correlated with leptin and negatively with vitamin D levels.

CONCLUSION

This study reveals a sexual dimorphism in LEAP-2 levels in children and adolescents. These changes and the higher levels during puberty imply that LEAP-2 may contribute to some of the biological adaptations occurring during pubertal development in terms of food intake, energy balance, growth rate, and puberty onset. Future studies assessing LEAP-2 levels in longitudinal studies and its implications in growth rate, puberty onset, and reproductive hormones will help to understand the relevance of this hormone in this stage of life.

The Peripubertal Decline in Makorin Ring Finger Protein 3 Expression is Independent of Leptin Action

A critical body weight is necessary for pubertal development, an effect mediated in part by leptin. The potential regulation by leptin of Makorin Ring Finger Protein 3 (MKRN3), in which loss-of-function mutations are the most common genetic cause of central precocious puberty, has not been previously explored. In mice, expression of Mkrn3 in the hypothalamic arcuate nucleus is high early in life and declines before the onset of puberty. Therefore, we aimed to explore if leptin contributes to the decrease in hypothalamic Mkrn3 mRNA levels observed in mice during pubertal development. We first used a leptin-deficient (ob/ob) mouse model. Mkrn3 mRNA levels in the mediobasal hypothalamus (MBH), which includes the arcuate nucleus, and in the preoptic area (POA), both showed a significant decrease with age from postnatal day (PND) 12 to PND30 in ob/ob mice in both males and females, similar to that observed in wild-type mice. To further explore the effects of leptin on Mkrn3 expression, we exposed prepubertal wild-type mice to high levels of leptin from age PND9-12, which did not result in any significant difference in Mkrn3 expression levels in either the MBH or POA. In summary, regulation of Mkrn3 expression by leptin was not observed in either the MBH or the POA, 2 hypothalamic sites important for pubertal maturation. These data suggest that the decline in Mkrn3 at the onset of puberty may occur independently of leptin and support our hypothesis that MKRN3 is a bona fide controller of puberty initiation.

NAFLD in women: Unique pathways, biomarkers and therapeutic opportunities

Purpose of review

In this review article we evaluate sex differences in the natural history of NAFLD and highlight distinct risk profiles of women with NAFLD, as well as unique treatment considerations and research gaps.

Summary of findings

Reproductive factors, such as menopausal status should be considered when evaluating NAFLD risk in women, as well as additional reproductive risk factors such as age at menarche, presence of polycystic ovary syndrome, and gestational diabetes. Women do appear to have lower risk for hepatocellular carcinoma from NASH, as well as lower mortality from NASH cirrhosis than men, although among women, NASH is now the leading indication for liver transplant. Data on sex differences in biomarker development and clinical trials are lacking, and researchers should be encouraged to evaluate biomarker performance by sex, and specifically report clinical trial endpoints in women.

Leptin and its actions on reproduction in males

Leptin, an adipocyte-derived hormone, serves numerous physiological functions in the body, particularly during puberty and reproduction. The exact mechanism by which leptin activates the gonadotropin-releasing hormone (GnRH) neurons to trigger puberty and reproduction remains unclear. Given the widespread distribution of leptin receptors in the body, both central and peripheral mechanisms involving the hypothalamic-pituitary-gonadal axis have been hypothesized. Leptin is necessary for normal reproductive function, but when present in excess, it can have detrimental effects on the male reproductive system. Human and animal studies point to leptin as a link between infertility and obesity, a suggestion that is corroborated by findings of low sperm count, increased sperm abnormalities, oxidative stress, and increased leptin levels in obese men. In addition, daily leptin administration to normal-weight rats has been shown to result in similar abnormalities in sperm parameters. The major pathways causing these abnormalities remain unidentified; however, these adverse effects have been attributed to leptin-induced increased oxidative stress because they are prevented by concurrently administering melatonin. Studies on leptin and its impact on sperm function are highly relevant in understanding and managing male infertility, particularly in overweight and obese men.

The Genetic Basis of Delayed Puberty

Delayed pubertal onset has many etiologies, but on average two-thirds of patients presenting with late puberty have self-limited (or constitutional) delayed puberty. Self-limited delayed puberty often has a strong familial basis. Segregation analyses from previous studies show complex models of inheritance, most commonly autosomal dominant, but also including autosomal recessive, bilineal, and X-linked. Sporadic cases are also observed. Despite this, the neuroendocrine mechanisms and genetic regulation remain unclear in the majority of patients with self-limited delayed puberty. Only rarely have mutations in genes known to cause aberrations of the hypothalamic-pituitary-gonadal axis been identified in cases of delayed puberty, and the majority of these are in relatives of patients with congenital hypogonadotropic hypogonadism (CHH), for example in the FGFR1 and GNRHR genes. Using next generation sequencing in a large family with isolated self-limited delayed puberty, a pathogenic mutation in the CHH gene HS6ST1 was found as the likely cause for this phenotype. Additionally, a study comparing the frequency of mutations in genes that cause GnRH deficiency between probands with CHH and probands with isolated self-limited delayed puberty identified that a significantly higher proportion of mutations with a greater degree of oligogenicity were seen in the CHH group. Mutations in the gene IGSF10 have been implicated in the pathogenesis of familial late puberty in a large Finnish cohort. IGSF10 disruption represents a fetal origin of delayed puberty, with dysregulation of GnRH neuronal migration during embryonic development presenting for the first time in adolescence as late puberty. Some patients with self-limited delayed puberty have distinct constitutional features of growth and puberty. Deleterious variants in FTO have been found in families with delayed puberty with extremely low BMI and maturational delay in growth in early childhood. Recent exciting evidence highlights the importance of epigenetic up-regulation of GnRH transcription by a network of miRNAs and transcription factors, including EAP1, during puberty. Whilst a fascinating heterogeneity of genetic defects have been shown to result in delayed and disordered puberty, and many are yet to be discovered, genetic testing may become a realistic diagnostic tool for the differentiation of conditions of delayed puberty.

Serum inhibin B concentration as a predictor of age at first menstruation in girls with idiopathic central precocious puberty

Objective

To compare the serum inhibin B, anti-Müllerian hormone (AMH) and leptin concentrations in girls with idiopathic central precocious puberty (CPP) to their concomitant characteristics and evaluate the capacity of each of these hormones to predict the age at first menstruation in those who were untreated and who completed their puberty.

Methods

This single-center study included 94 girls selected from a cohort of 493 girls seen between 1981 and 2012 and diagnosed with idiopathic CPP for whom a remaining serum sample collected at the initial evaluation was available. Of these 25 were untreated and completed their puberty.

Results- correlations at initial evaluation

In the whole cohort the inhibin B concentration displayed significant positive correlations with the age at the onset of puberty and at initial evaluation; bone age; breast Tanner stage; serum basal estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and AMH concentrations, LH peak and LH/FSH peak ratio. The AMH concentration displayed a significant positive correlation with serum estradiol and a negative correlation with basal FSH concentration. The leptin concentration displayed significant positive correlations with the age at initial evaluation, bone age, and body mass index and a negative correlation with the FSH peak.

Results- prediction of age at first menstruation

In 25 untreated girls, the inhibin B concentration was negatively correlated with the age at first menstruation (r = -0.61, p = 0.001) and the time between the onset of puberty and first menstruation (r = -0.59, p = 0.002). Inhibin B concentrations <30 pg/mL were associated with a time between the onset of puberty and first menstruation ≥3 years in 14/15 patients with a sensitivity of 0.67 and a specificity of 0.75. The age at first menstruation was estimated using a formula: min (11.15–0.510 LH/FSH peak ratio, 11.57–0.025 inhibin B)available at: http://www.kamick.org/lemaire/med/girls-cpp18.html.

Conclusion

We established formulas based on the serum inhibin B concentrations and LH/FSH peak ratio at the initial evaluation, alone or in combination, to predict the age at first menstruation in girls with CPP. These formulas can assist with determining the indications for treatment in CPP.

Leptin Elevation as a Risk Factor for Slipped Capital Femoral Epiphysis Independent of Obesity Status

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is strongly associated with childhood obesity, yet the prevalence of obesity is orders of magnitude greater than the prevalence of SCFE. Therefore, it is hypothesized that obesity is not, by itself, a sufficient condition for SCFE, but rather one component of a multifactorial process requiring preexisting physeal pathology. Leptin elevation is seen to varying degrees in patients with obesity, and as leptin has been shown to cause physeal pathology similar to the changes seen in SCFE, we propose that leptin may be a factor distinguishing between patients with SCFE and equally obese children without hip abnormalities.

METHODS

Serum leptin levels were obtained from 40 patients with SCFE and 30 control patients with approximate body mass index (BMI) matching. BMI percentiles were calculated according to Centers for Disease Control and Prevention population data by patient age and sex. Patients were compared by demographic characteristics, leptin levels, odds of leptin elevation, and odds of SCFE.

RESULTS

The odds of developing SCFE was increased by an odds ratio of 4.9 (95% confidence interval [CI], 1.31 to 18.48; p < 0.02) in patients with elevated leptin levels, regardless of obesity status, sex, and race. When grouping patients by their obesity status, non-obese patients with SCFE showed elevated median leptin levels at 5.8 ng/mL compared with non-obese controls at 1.7 ng/mL (p = 0.006). Similarly, obese patients with SCFE showed elevated median leptin levels at 17.9 ng/mL compared with equally obese controls at 10.5 ng/mL (p = 0.039). Serum leptin levels increased in association with obesity (p < 0.001), with an increase in leptin of 0.17 ng/mL (95% CI, 0.07 to 0.27 ng/mL) per BMI percentile point.

CONCLUSIONS

To our knowledge, this study is the first to clinically demonstrate an association between elevated serum leptin levels and SCFE, regardless of BMI. This adds to existing literature suggesting that SCFE is a multifactorial process and that leptin levels may have profound physiological effects on the development of various disease states. Despite a strong association with adiposity, leptin levels vary between patients of equal BMI and may be a vital resource in prognostication of future obesity-related comorbidities.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

From Placenta to Polycystic Ovarian Syndrome: The Role of Adipokines

Adipokines are cytokines produced mainly by adipose tissue, besides many other tissues such as placenta, ovaries, peripheral-blood mononuclear cells, liver, muscle, kidney, heart, and bone marrow. Adipokines play a significant role in the metabolic syndrome and in cardiovascular diseases, have implications in regulating insulin sensitivity and inflammation, and have significant effects on growth and reproductive function. The objective of this review was to analyze the functions known today of adiponectin, leptin, resistin, and visfatin from placenta throughout childhood and adolescence. It is well known now that their serum concentrations during pregnancy and lactation have long-term effects beyond the fetus and newborn. With regard to puberty, adipokines are involved in the regulation of the relationship between nutritional status and normal physiology or disorders of puberty and altered gonadal function, as, for example, premature pubarche and polycystic ovarian syndrome (PCOS). Cytokines are involved in the maturation of oocytes and in the regular progression of puberty and pregnancy.

Influence of sex steroid hormones on the adolescent brain and behavior: An update

This review explains the main effects exerted by sex steroids and other hormones on the adolescent brain. During the transition from puberty to adolescence, these hormones participate in the organizational phenomena that structurally shape some brain circuits. In adulthood, this will propitiate some specific behavior as responses to the hormones now activating those neural circuits. Adolescence is, then, a critical "organizational window" for the brain to develop adequately, since steroid hormones perform important functions at this stage. For this reason, the adolescent years are very important for future behaviors in human beings. Changes that occur or fail to occur during adolescence will determine behaviors for the rest of one's lifetime. Consequently, understanding the link between adolescent behavior and brain development as influenced by sex steroids and other hormones and compounds is very important in order to interpret various psycho-affective pathologies. Lay Summary : The effect of steroid hormones on the development of the adolescent brain, and therefore, on adolescent behavior, is noticeable. This review presents their main activational and organizational effects. During the transition from puberty to adolescence, organizational phenomena triggered by steroids structurally affect the remodeling of brain circuits. Later in adulthood, these changes will be reflected in behavioral responses to such hormones. Adolescence can then be seen as a fundamental "organizational window" during which sex steroids and other hormones and compounds play relevant roles. The understanding of the relationship between adolescent behavior and the way hormones influence brain development help understand some psychological disorders.

Assessment of left ventricular mass index could predict metabolic syndrome in obese children

BACKGROUND

Childhood obesity is a major risk factor for cardiovascular diseases in children and adults.

OBJECTIVES

The purpose of this study was to evaluate the serum leptin level and the cardiac changes in normotensive obese children and to study the relationship between left ventricular mass index (LVMI) and serum leptin with the parameters of metabolic syndrome (MS) in obese children.

METHODS

This study was conducted in al Jeddani Hospital and Ibn Sina College Hospital in Saudi Arabia in the period from July 2012 to December 2013, and included 82 obese children. Their mean age was 10.2 ± 2.8 years; they were divided into 25 obese children with MS and 57 obese children without MS, and 40 healthy age- and sex-matched children were also included in the study as a control group. All children were subjected to clinical assessment including standing height, body weight, body mass index (BMI), waist circumference (WC), and blood pressure measurements. All children received an echocardiographic examination (2-dimensional, M-mode, Doppler, and tissue Doppler echocardiograpy) and laboratory assessment of serum leptin level, fasting glucose, fasting insulin, the homeostatic model assessment for insulin resistance (HOMA) index, total cholesterol, triglycerides, and high- and low-density lipoprotein profile.

RESULTS

BMI, BMI standard deviation score, WC, fasting glucose, fasting insulin, HOMA index and the serum leptin level were significantly higher in obese children compared to control group (p < 0.05). The LVMI were increased in the obese compared to the control group (p < 0.001) while left ventricle systolic and diastolic functions did not differ in obese versus control group (p > 0.05). There was a significant positive correlation between both LVMI and serum leptin level in comparison to BMI, WC, fasting glucose, fasting insulin, HOMA, triglycerides, and low-density lipoprotein in all obese children, especially the MS group. However, there was a significant negative correlation between both LVMI and serum leptin level in comparison to high-density lipoprotein.

CONCLUSION

Assessment of LVMI as routine echocardiographic examinations and serum leptin level might be a feasible and reliable method for the evaluation of obesity and its related cardiovascular risks during childhood that can predict metabolic syndrome and insulin resistance.

Insulin Resistance of Puberty

Puberty is a time of considerable metabolic and hormonal change. Notably, puberty is associated with a marked decrease in insulin sensitivity, on par with that seen during pregnancy. In otherwise healthy youth, there is a nadir in insulin sensitivity in mid-puberty, and then it recovers at puberty completion. However, there is evidence that insulin resistance (IR) does not resolve in youth who are obese going into puberty and may result in increased cardiometabolic risk. Little is known about the underlying pathophysiology of IR in puberty, and how it might contribute to increased disease risk (e.g., type 2 diabetes). In this review, we have outlined what is known about the IR in puberty in terms of pattern, potential underlying mechanisms and other mediating factors. We also outline other potentially related metabolic changes that occur during puberty, and effects of underlying insulin resistant states (e.g., obesity) on pubertal changes in insulin sensitivity.

Testosterone concentration and insulin sensitivity in young men with type 1 and type 2 diabetes

OBJECTIVE

Reduced testosterone, a recognized comorbidity of reduced insulin sensitivity (IS) and type 2 diabetes (T2D), has also been reported in adult males with type 1 diabetes (T1D). However, there are limited data on how early reduced testosterone occurs, and whether it is related to the reduced IS in T1D. Leptin, a modulator of the HPG-axis, may also influence testosterone in T1D. We hypothesized that IS and leptin would be associated with total testosterone (TT), and free androgen index (FAI) in adolescent males with T1D.

METHODS

T1D (n = 35), T2D (n = 13), lean (n = 13) and obese (n = 9) adolescent males had IS measured by hyperinsulinemic-euglycemic clamps (glucose infusion rate [GIR]), in addition to leptin, sex hormone binding globulin (SHBG), TT, and FAI. The cohort was stratified into those with T1D (n = 35) and those without (n = 35).

RESULTS

TT and SHBG were lower in T2D boys vs. lean controls, and GIR and leptin correlated with FAI and TT in non-T1D participants. However, despite being insulin resistant, adolescent males with T1D had normal TT and FAI, unrelated to GIR. In T1D, leptin was inversely associated with TT (p = 0.005) and FAI (p = 0.01), independent of puberty, hemoglobin A1c (HbA1c), diabetes duration, body mass index (BMI) z-score and GIR.

CONCLUSION

Leptin accounted for a significant proportion of the variability of testosterone in T1D. However, despite reduced IS, there was no association between IS and testosterone in T1D adolescents. These observations suggest that the mechanisms affecting testosterone may differ between adolescent males with and without T1D.

Morningness-Eveningness and Physical Activity in Adolescent Girls: Menarche as a Transition Point

This study identified trajectories of morningness-eveningness (M-E) and physical activity when chronological (i.e., time since birth) versus gynecological (i.e., time since menarche) age is used to indicate maturation. Piecewise models were fit for girls (N = 262, ages 11-19) using chronological or gynecological age as the time metric. Girls stayed up later (i.e., eveningness) as they approach menarche. After menarche no change in M-E was observed. In contrast, no change in M-E was detected with chronological age. No change in physical activity was observed before menarche, and physical activity declined after menarche. With chronological age, physical activity declined as girls got older. Gynecological age may be more appropriate than chronological age as a metric for understanding changes in M-E and physical activity.

Association of diethylhexyl phthalate with obesity-related markers and body mass change from birth to 3 months of age

BACKGROUND

Several studies have suggested potential links of phthalates to obesity in children and adults. Limited evidence, however, has been available for the relations between diethylhexyl phthalate (DEHP) and obesity-related markers or body mass change in early life.

METHODS

128 healthy pregnant women were recruited and, after delivery, their newborns' first urine and umbilical cord blood samples were collected. We measured urinary levels of two DEHP metabolites, mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP). We also measured the levels of leptin, total cholesterol and triglyceride (TG) in cord serum, and used them along with weight, length, head circumference and ponderal index (PI, 100 g/cm(3)) at birth, as obesity-related markers, and estimated the relations between DEHP metabolites and obesity-related markers using generalised linear models. For the evaluation of body mass increase by early life DEHP exposure, body mass index (BMI) z-score change during 3 months after birth by DEHP metabolites in the first urine samples of the newborns were evaluated using logistic regression.

RESULTS

DEHP exposure was associated with decrease of PI and increase of TG (PI, β=-0.11, p=0.070 and TG, β=0.14, p=0.027), especially for boys (PI, β=-0.13, p=0.021; and TG, β=0.19, p=0.025). Moreover, DEHP exposure was positively associated with body mass increase during 3 months after birth (change of BMI z-scores, OR=4.35, p=0.025).

CONCLUSIONS

Our findings suggest that DEHP exposure may affect body mass change in early life through changes of obesity-related markers.

The development of youth-onset severe obesity in urban US girls

•

Youth-onset severe obesity warrants particular concern in urban female populations.

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Among 2226 girls, prevalence was 8.3% at age 7–10, 10.8% at age 12–15 and fairly stable over teen years.

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Severe obesity prevalence increased more rapidly with age for girls born in 1995 versus 1992.

•

Severely obese girls' BMI grew 2.6 times as fast as normal-BMI peers in the transition to adolescence.

•

Late childhood and early adolescence is a key developmental window for prevention and treatment.

Objective

To understand the incidence and persistence of severe obesity (≥1.2 × 95th BMI percentile-for-age) in girls across the transition to adolescence, and map developmental trajectories of adolescent severe obesity in a high-risk sample.

Methods

We examined ten years of prospectively collected data from a population sample of urban girls (n = 2226; 53% African American, aged 7–10 in 2003–2004). We determined severe obesity prevalence and incidence by age. Logistic regression evaluated for secular trend in the association between age and severe obesity prevalence. Unconditional latent growth curve models (LGCMs) compared BMI development through the adolescence transition between girls with severe obesity versus healthy BMI.

Results

Severe obesity prevalence was 8.3% at age 7–10 and 10.1% at age 16–19 (white: 5.9%; African American: 13.2%; p < 0.001). Age-specific prevalence increased more rapidly among the latest-born, versus earliest-born, girls (p = 0.034). Incidence was 1.3% to 2.4% annually. When we compared 12–15 year-old girls with severe obesity versus healthy BMI, average body weight was already distinct 5 years earlier (16.5 kg versus 25.7 kg; p < 0.001) and the BMI difference between groups increased annually. LGCMs between ages 7–10 and 11–14 indicated an increase of 3.32 kg/m² in the healthy-BMI group and 8.50 kg/m² in the severe obesity group, a 2.6-fold difference.

Conclusions

Youth-onset severe obesity warrants particular concern in urban girls due to high prevalence and an increasing secular prevalence trend. Late childhood and early adolescence may represent a key developmental window for prevention and treatment, but is too late to prevent youth-onset severe obesity entirely.

Reference values for leptin and adiponectin in children below the age of 10 based on the IDEFICS cohort

OBJECTIVE

To establish age- and sex-specific reference values for serum leptin and adiponectin in normal-weight 3.0-8.9-year old European children.

SUBJECTS AND METHODS

Blood samples for hormone analysis were taken from 1338 children of the IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS) study cohort. Only normal-weight children aged 3.0-8.9 years were included (n=539) in our analysis. Using the General Additive Model for Location Scale and Shape, age- and sex-specific percentiles were derived. The influence of under/overweight and obesity on the proposed reference curves based on normal-weight children was investigated in several sensitivity analyses using the sample without obese children (n=1015) and the whole study sample (n=1338).

RESULTS

There was a negative age trend of adiponectin blood levels and a positive trend of leptin levels in boys and girls. Percentiles derived for girls were generally higher than those obtained for boys. The corresponding age-specific differences of the 97th percentile ranged from -2.2 to 4.6 μg ml(-1) and from 2.2 to 4.8 ng ml(-1) for adiponectin and leptin, respectively.

CONCLUSIONS

According to our knowledge, these are the first reference values of leptin and adiponectin in prepubertal, normal-weight children. The presented adiponectin and leptin reference curves may allow for a more differentiated interpretation of children's hormone levels in epidemiological and clinical studies.

Plasma Leptin Levels in Children Hospitalized with Cholera in Bangladesh

Vibrio cholerae, the cause of cholera, induces both innate and adaptive immune responses in infected humans. Leptin is a hormone that plays a role in both metabolism and mediating immune responses. We characterized leptin levels in 11 children with cholera in Bangladesh, assessing leptin levels on days 2, 7, 30, and 180 following cholera. We found that patients at the acute stage of cholera had significantly lower plasma leptin levels than matched controls, and compared with levels in late convalescence. We then assessed immune responses to V. cholerae antigens in 74 children with cholera, correlating these responses to plasma leptin levels on day 2 of illness. In multivariate analysis, we found an association between day 2 leptin levels and development of later anti-cholera toxin B subunit (CtxB) responses. This finding appeared to be limited to children with better nutritional status. Interestingly, we found no association between leptin levels and antibody responses to V. cholerae lipopolysaccharide, a T cell-independent antigen. Our results suggest that leptin levels may be associated with cholera, including the development of immune responses to T cell-dependent antigens.

Growth hormone responses to provocative tests in children with short stature

Growth hormone deficiency (GHD) is defined as a serum peak GH concentration <10 ng/mL with provocation as tested by a combination of at least two separate tests. The aim of this study was to compare two standard tests, insulin and levodopa (L-dopa), with a primary focus on specificity and accuracy. Clinical data were collected retrospectively from a review of 120 children who visited the pediatric endocrine clinic at Chonnam National University Hospital for the evaluation of short stature between January 2006 and April 2014. Subjects underwent GH provocation tests with insulin and L-dopa. Blood samples were obtained at 0, 15, 30, 45, 60, 90, and 120 min after administration, and GH levels were measured. In the insulin test, serial glucose levels were also checked, closely monitoring hypoglycemia. A total of 83 children (69.2%) were diagnosed with GHD and 37 children (30.8%) were diagnosed with idiopathic short stature (ISS). Peak GH levels were achieved an average of 45 min after the administration of insulin and L-dopa for both groups. The specificity and accuracy were 78.4% and 93.6% for the insulin test and 29.7% and 79.2% for L-dopa test, respectively. In the ISS group, the cumulative frequency of a GH cutoff value of >10 ng/mL at 120 min was 75.6% after insulin stimulation compared with 35.1% after L-dopa stimulation. Considering these results, we recommend performing the insulin test first to exclude ISS and then the L-dopa test for the diagnosis of GHD. This way, ISS patients are diagnosed after a single test, thus reducing hospital days and the burden of undergoing two serial tests.

Association between chlorinated pesticides in the serum of prepubertal Russian boys and longitudinal biomarkers of metabolic function

Organochlorine pesticides (OCPs) have been linked to adult metabolic disorders; however, few studies have examined these associations in childhood. We prospectively evaluated the associations of baseline serum OCPs (hexachlorobenzene, β-hexachlorocyclohexane, and p,p'-dichlorodiphenyldichloroethylene) in Russian boys with subsequent repeated measurements of serum glucose, insulin, lipids, leptin, and calculated homeostatic model assessment of insulin resistance (IR). During 2003-2005, we enrolled 499 boys aged 8-9 years in a prospective cohort; 318 had baseline serum OCPs and serum biomarkers measured at ages 10-13 years. Multivariable generalized estimating equation and mediation regression models were used to examine associations and direct and indirect (via body mass index (BMI) (weight (kg)/height (m)(2))) effects of prepubertal OCP tertiles and quintiles with biomarkers. In multivariable models, higher p,p'-dichlorodiphenyldichloroethylene (quintile 5 vs. quintile 1) was associated with lower leptin, with relative mean decreases of 61.8% (95% confidence interval: 48.4%, 71.7%) in models unadjusted for BMI and 22.2% (95% confidence interval: 7.1%, 34.9%) in models adjusted for BMI; the direct effect of p,p'-dichlorodiphenyldichloroethylene on leptin accounted for 27% of the total effect. IR prevalence was 6.6% at ages 12-13 years. Higher hexachlorobenzene (tertile 3 vs. tertile 1) was associated with higher odds of IR in models adjusted for BMI (odds ratio = 4.37, 95% confidence interval: 1.44, 13.28). These results suggest that childhood OCPs may be associated with IR and lower leptin.

Correlates of leptin in children with chronic kidney disease

OBJECTIVE

To investigate the relative associations of renal function, obesity, and inflammation with serum leptin levels in children with chronic kidney disease (CKD).

STUDY DESIGN

This was a cross-sectional analysis of 317 children from the Chronic Kidney Disease in Children study, a large cohort of pediatric patients with stage II-IV CKD. Linear regression modeling was used to evaluate the association of serum leptin level with glomerular filtration rate calculated using the plasma iohexol disappearance curve, demographics, body mass index (BMI), and cardiovascular risk factors, including inflammatory cytokines, insulin resistance, and serum lipid levels.

RESULTS

In univariate analyses, elevated serum leptin level was significantly associated with increased BMI, older age, and female sex (P < .001 for all). Leptin level also correlated positively with serum triglycerides and insulin resistance (P < .001) and negatively with serum high-density lipoprotein cholesterol (P = .002). Leptin level was not associated with glomerular filtration rate calculated using the plasma iohexol disappearance curve or inflammatory cytokines. In multivariate analysis, BMI, age, female sex, and serum triglyceride levels were significantly associated with serum leptin level.

CONCLUSION

Increased leptin production was associated with female sex, older age, and adiposity in children with mild to moderate CKD. Renal function was not associated with serum leptin level, indicating that decreased clearance does not contribute to elevated leptin levels.

Leptin deficiency in maltreated children

Consistent with findings from experimental research in nonhuman primates exposed to early-life stress, children exposed to maltreatment are at high risk of detrimental physical health conditions, such as obesity and systemic inflammation. Because leptin is a key molecule involved in the regulation of both energy balance and immunity, we investigated abnormalities in leptin physiology among maltreated children. We measured leptin, body mass index and C-reactive protein in 170 12-year-old children members of the Environmental-Risk Longitudinal Twin Study, for whom we had prospectively-collected information on maltreatment exposure. We found that maltreated children exhibited blunted elevation in leptin levels in relation to increasing levels of physiological stimuli, adiposity and inflammation, compared with a group of non-maltreated children matched for gender, zygosity and socioeconomic status. These findings were also independent of key potential artifacts and confounders, such as time of day at sample collection, history of food insecurity, pubertal maturation and depressive symptoms. Furthermore, using birth weight as a proxy measure for leptin, we found that physiological abnormalities were presumably not present at birth in children who went on to be maltreated but only emerged over the course of childhood, after maltreatment exposure. Leptin deficiency may contribute to onset, persistence and progression of physical health problems in maltreated children.

Temporal relationship between insulin sensitivity and the pubertal decline in physical activity in peripubertal Hispanic and African American females

OBJECTIVE

Little attention has been paid to possible intrinsic biological mechanisms for the decline in physical activity that occurs during puberty. This longitudinal observational study examined the association between baseline insulin sensitivity (SI) and declines in physical activity and increases in sedentary behavior in peripubertal minority females over a year.

RESEARCH DESIGN AND METHODS

Participants were Hispanic and African American girls (n = 55; 76% Hispanic; mean age 9.4 years; 36% obese). SI and other insulin indices were measured at baseline using the frequently sampled intravenous glucose tolerance test. Physical activity was measured on a quarterly basis by accelerometry and self-report.

RESULTS

Physical activity declined by 25% and time spent in sedentary behaviors increased by ∼13% over 1 year. Lower baseline SI predicted the decline in physical activity measured by accelerometry, whereas higher baseline acute insulin response to glucose predicted the decline in physical activity measured by self-report. Time spent in sedentary behavior increased by ~13% over 1 year, and this was predicted by lower baseline SI. All models controlled for adiposity, age, pubertal stage, and ethnicity.

CONCLUSIONS

When evaluated using a longitudinal design with strong outcome measures, this study suggests that lower baseline SI predicts a greater decline in physical activity in peripubertal minority females.

Median ages at stages of sexual maturity and excess weight in school children

BACKGROUND

We aimed to estimate the median ages at specific stages of sexual maturity stratified by excess weight in boys and girls.

MATERIALS AND METHOD

This was a cross-sectional study made in 2007 in Florianopolis, Brazil, with 2,339 schoolchildren between 8 to 14 years of age (1,107 boys) selected at random in two steps (by region and type of school). The schoolchildren were divided into: i) those with excess weight and ii) those without excess weight, according to the WHO 2007 cut-off points for gender and age. Sexual maturity was self-evaluated by the subjects according to the Tanner sexual development stages, and utilizing median ages for the genitalia, breasts, and pubic hair stages.

RESULTS

In the boys with excess weight, precocity was observed in the stages 4 for genitals and pubic hair and 2 for pubic hair, with the values for excess and normal weight. The median ages at the beginning of puberty (stage 2-sexual development) for boys and girls in Florianopolis were 10.8 and 10.3 years, respectively.

CONCLUSION

Excess weight is associated with lower median ages in the sexual maturity stages in boys and girls and that it should be taken into account when evaluating sexual maturity in children and adolescents.

Analysis of Gln223Agr polymorphism of Leptin Receptor Gene in type II diabetic mellitus subjects among Malaysians

Leptin is known as the adipose peptide hormone. It plays an important role in the regulation of body fat and inhibits food intake by its action. Moreover, it is believed that leptin level deductions might be the cause of obesity and may play an important role in the development of Type 2 Diabetes Mellitus (T2DM), as well as in cardiovascular diseases (CVD). The Leptin Receptor (LEPR) gene and its polymorphisms have not been extensively studied in relation to the T2DM and its complications in various populations. In this study, we have determined the association of Gln223Agr loci of LEPR gene in three ethnic groups of Malaysia, namely: Malays, Chinese and Indians. A total of 284 T2DM subjects and 281 healthy individuals were recruited based on International Diabetes Federation (IDF) criteria. Genomic DNA was extracted from the buccal specimens of the subjects. The commercial polymerase chain reaction (PCR) method was carried out by proper restriction enzyme MSP I to both amplify and digest the Gln223Agr polymorphism. The p-value among the three studied races was 0.057, 0.011 and 0.095, respectively. The values such as age, WHR, FPG, H_bA_1C, LDL, HDL, Chol and Family History were significantly different among the subjects with Gln223Agr polymorphism of LEPR (p < 0.05).

What is in our environment that effects puberty?

Recent studies indicate that the onset of puberty is occurring at increasingly younger ages. Many etiologies have been hypothesized to be involved, but environmental exposures are among the most worrisome. Multiple organizations have endorsed the need to study and provide clinical awareness regarding the effect of a child's environment on pubertal timing. This review article summarizes the current understanding of the major environmental influences on pubertal timing, focusing on factors for which the most scientific evidence exists. The research reviewed addresses intrinsic factors unique to each individual, naturally occurring endocrine disruptors and chemical endocrine disruptors. In each category, evidence was found for and against the involvement of specific environmental factors on pubertal timing. Ultimately, an individual's environment is likely comprised of many aspects that collectively contribute to the timing of puberty. The need for research aimed at elucidating the effects of numerous specific yet disparate forms of exposures is emphasized.

Does Q223R Polymorphism of Leptin Receptor Influence on Anthropometric Parameters and Bone Density in Childhood Cancer Survivors?

Childhood cancer survivors are in augmented risk for developing obesity. For many factors leptin and leptin receptor gene polymorphism play an important role in the development and metabolism not only of fat, but also, bone tissue. The aim of the analysis was to find the relationships between Q223R, leptin levels, and anthropometric parameters. Patients and Methods. In the study 74 cancer survivors participated (ALL n = 64, lymphomas n = 10), and the control group consisted of 51 healthy peers. Leptin blood concentration was determined by ELISA method. To estimate leptin receptor gene polymorphism, RFLP method was used. Bone mineral density (BMD) and content (BMC), fat, and lean tissue measurements were obtained by DXA. Results. We found no correlations between serum leptin concentrations and anthropometric parameters nor BMD. Serum leptin concentrations were significantly lower in the group of cancer survivors compared to controls; however, in those overweight from examined group we found leptin levels higher than those in nonoverweight. Genotype Q223R was not associated with higher leptin levels, BMI, BMD, body fat or lean tissue. Conclusion. To our knowledge, this is the first report describing the relationship between BMD and Q223R polymorphism in childhood cancer survivors. Further analysis, based on a larger group of patients, is needed to confirm these findings.

Leptin levels in children and adults with classic galactosaemia

Among the long-term complications of Classic Galactosaemia (Gal) is premature ovarian insufficiency (POI) in female patients with subtle abnormalities of reproductive function also reported in male patients. Leptin is a circulating hormone which reflects body energy stores and which affects the neuroendocrine reproductive axis and pubertal development.We measured serum leptin in 28 children (10 girls, 18 boys; mean age 7.6 years, range 0.5-17.9 years) and in 22 adults (10 females, 12 males; mean age 23.9 years, range 18-37 years) with Gal on a strict galactose-restricted diet in comparison with control data.Leptin levels (expressed as SDS for gender and pubertal stage) were lower in Gal children than controls (mean leptin-SDS = -0.71 for girls, p < 0.05, -0.97 for boys compared with SDS = 0 for controls, p < 0.05). In an age-related analysis, leptin levels did not correlate with age in children with Gal for both sexes as it did for matched controls.As expected, females had higher leptin levels than males in either group. In adults with Gal, leptin concentrations were within normal limits for both sexes when adjusted for gender and BMI. There was a linear relationship between log-leptin and BMI in children with Gal and in controls. For Gal women, log-leptin was also associated with BMI. However, for Gal men, and hence for the entire group of adult Gal patients, this association between log-leptin and BMI was not detectable. Our findings suggest that leptin dysregulation may play a role in fertility issues in individuals with Gal from an early age.

Serum leptin levels in healthy adolescents: Effects of gender and growth

OBJECTIVES

The purposes of this paper were to evaluate the serum leptin levels in healthy adolescents and to establish standard age variation curves.

METHODS

Nine hundred six (414 boys and 492 girls) healthy adolescents were investigated. The maximum increment age in height (MIA) was identified in 124 boys and 130 girls. The menarcheal age (MA) was obtained for 130 girls. Fasting leptin levels were measured by enzyme immunoassay. The MIA was calculated by proportional allotment of yearly height increments.

RESULTS

Serum leptin levels did not change in boys and girls from the ages of 9 to 11. They decreased after the age of 11 in boys, while they increased in girls. Stepwise multiple regression analysis revealed that serum leptin levels were closely related to pubertal stage. The levels decreased remarkably after MIA in boys and increased remarkably after MA in girls. We drew standard age variation curves of serum leptin levels by calculating the 25th, 50th and 75th percentiles for each age in both boys and girls. The percentile curves for boys were divided into pre-MIA and post-MIA curves. Those for girls were divided into pre-MA and post-MA curves.

CONCLUSION

We have devised a potentially useful method for evaluating serum leptin levels in adolescents considering the effects of gender and growth.

Systemic inflammation in childhood obesity: circulating inflammatory mediators and activated CD14++ monocytes

AIMS/HYPOTHESIS

In adults, circulating inflammatory mediators and activated CD14(++) monocytes link obesity to its metabolic and cardiovascular complications. However, it is largely unknown whether these inflammatory changes already occur in childhood obesity. To survey inflammatory changes during the early stages of obesity, we performed a comprehensive analysis of circulating inflammatory mediators, monocyte populations and their function in childhood obesity.

METHODS

In lean and obese children aged 6 to 16 years (n = 96), 35 circulating inflammatory mediators including adipokines were measured. Hierarchical cluster analysis of the inflammatory mediator profiles was performed to investigate associations between inflammatory mediator clusters and clinical variables. Whole-blood monocyte phenotyping and functional testing with the toll-like receptor 4 ligand, lipopolysaccharide, were also executed.

RESULTS

First, next to leptin, the circulating mediators chemerin, tissue inhibitor of metalloproteinase 1, EGF and TNF receptor 2 were identified as novel inflammatory mediators that are increased in childhood obesity. Second, cluster analysis of the circulating mediators distinguished two obesity clusters, two leanness clusters and one mixed cluster. All clusters showed distinct inflammatory mediator profiles, together with differences in insulin sensitivity and other clinical variables. Third, childhood obesity was associated with increased CD14(++) monocyte numbers and an activated phenotype of the CD14(++) monocyte subsets.

CONCLUSIONS/INTERPRETATION

Inflammatory mediator clusters were associated with insulin resistance in obese and lean children. The activation of CD14(++) monocyte subsets, which is associated with increased development of atherosclerosis in obese adults, was also readily detected in obese children. Our results indicate that inflammatory mechanisms linking obesity to its metabolic and cardiovascular complications are already activated in childhood obesity.

Obesity and its diagnostic methods in Turkish children

OBJECTIVE

The application of body mass index (BMI) for obesity classification in all population studies has been questioned by the scientific community. It has been found that the bioelectrical impedance analysis (BIA) is an accurate method for screening obesity. This study was conducted to evaluate the accuracies of BMI, skinfold thickness (SFT), leptin and BIA measurements in obesity classification and to find correlations between BIA and the other indicators for obesity.

MATERIALS AND METHODS

This case-control study included 178 children of whom 90 were in the obese group and 88 in the control group. The study measured BMI, SFT, leptin level and BIA-mediated body fat percentage (BIA BFP) in each child.

RESULTS

The BMIs, leptin levels, SFTs and BIA BFPs of children in the obese group were found to be higher than those in the control group (p<0.001). The measurement of BIA BFP strongly correlated with BMI, SFT and waist circumference, whereas BIA BFP measurement showed weak-moderate correlation with leptin level.

CONCLUSION

Bioelectrical impedance analysis was found to be an accurate measure of BFP in obesity. In addition, BIA may prevent the incorrect diagnosis of obesity as determined by BMI alone, especially in boys during the pubertal period.

Body weight impact on puberty: effects of high-calorie diet on puberty onset in female rhesus monkeys

Secular trends toward a declining age at puberty onset with correlated changes in body weight have been reported in economically advanced countries. This has been attributed to excess calorie intake along with reduced physical activity in children. However, because the timing of puberty in humans is also influenced by other factors, such as genetic traits, living conditions, geographical location, and environmental chemicals, it is difficult to distinguish the effect of diet and body size from other factors in a human population. Here we report that feeding juvenile female rhesus monkeys born and raised at the Wisconsin National Primate Research Center with a high-calorie diet results in acceleration of body growth and precocious menarche. The monkeys fed a high-calorie diet also had an elevated body mass index. The most significant treatment effects on circulating hormones were increased leptin and IGF-I levels throughout the experiment. The findings of this study suggest the importance of close monitoring of juvenile feeding behaviors as an important intervention to reduce the prevalence of precocious development and metabolic diseases in adulthood.

Genetic variation within a metabolic motif in the chromogranin a promoter: pleiotropic influence on cardiometabolic risk traits in twins

BACKGROUND

The cardiometabolic syndrome comprised of multiple correlated traits, but its origin is incompletely understood. Chromogranin A (CHGA) is required for formation of the catecholamine secretory pathway in sympathochromaffin cells. In twin pair studies, we found that CHGA traits aggregated with body mass index (BMI), as well as its biochemical determinant leptin. METHODS Here we used the twin method to probe the role of heredity in generating such risk traits, and then investigated the role of risk-trait-associated CHGA promoter genetic variation in transfected chromaffin cells. Trait heritability (h(2)) and shared genetic determination among traits (pleiotropy, genetic covariance, ρ(G)) were estimated by variance components in twin pairs.

RESULTS

CHGA, BMI, and leptin each displayed substantial h(2), and the traits also aggregated with several features of the metabolic syndrome (e.g., insulin resistance, blood pressure (BP), hypertension, catecholamines, and C-reactive protein (CRP)). Twin studies demonstrated genetic covariance (pleiotropy, ρ(G)) for CHGA, BMI, and leptin with other metabolic traits (insulin resistance, BP, and CRP). We therefore investigated the CHGA locus for mechanisms of codetermination with such metabolic traits. A common functional variant in the human CHGA promoter (G-462A, rs9658634, minor allele frequency ~21%) was associated with leptin and CRP secretion, as well as BMI, especially in women; marker-on-trait effects on BMI were replicated across twin populations on two continents. In CHGA promoter/luciferase reporter plasmids transfected into chromaffin cells, G-462A alleles differed markedly in reporter expression. The G-462A variant disrupted predicted transcriptional control by a PPARγ/RXRα motif and costimulation by PPARγ/RXRα and their cognate ligands, differentially activated the two alleles. During chromatin immunoprecipitation, endogenous PPARγ bound the motif.

CONCLUSIONS

Multiple features of the metabolic syndrome are thus under joint (pleiotropic) genetic determination, with CHGA as one such contributory locus: a common polymorphism in the promoter (G-462A) of CHGA predicts such heritable metabolic traits as BMI and leptin. CHGA promoter variant G-462A was not only associated with such metabolic traits but also disrupted a PPARγ/RXRα motif and responded differentially to characteristic trans-activators of that motif. The results suggest novel links between the catecholaminergic system and risk for the metabolic syndrome as well as systemic hypertension.

Gender differences in serum leptin concentrations from umbilical cord blood of newborn infants born to nondiabetic, gestational diabetic and type-2 diabetic mothers

To investigate gender differences, if any, in leptin concentrations from umbilical cord blood of new born infants of mothers with type 2 diabetes mellitus (DM), gestational diabetes mellitus (GDM), and Non diabetic (ND) at delivery. Serum leptin concentrations were measured in 105 newborns (53 males and 52 females in the three groups). Blood was taken from the umbilical cord of the babies at delivery. Maternal anthropometric measurements were recorded within 48 hours after delivery. Pearson correlation coefficient was used to explore the relationship between serum leptin concentrations and anthropometric measures of the fetus and their mother. Both Serum leptin level and serum C-peptide was measured by chemiluminescence based ELISA. The median range of leptin concentration in cord blood was ND group: Male [13.91 (3.22 - 47.63)], Female [16.88 (2 - 43.65)]; GDM group: Male [32 (7 - 76.00)], Female [36.73 (4.80 - 81.20)]; DM group: Male [20.90 (2 -76.00)], Female [32 {2.58 - 80.67)]. Cord serum leptin levels correlated with birth weight(r=0.587, p=0.0001), ponderal index (PI) (r=.319, p=0.024)of the babies and body mass index (BMI) (r=-0.299, p=0.035) of their mothers but did not correlate with gestational age, cord serum C-peptide concentration or placental weight at delivery. Leptin concentrations were higher in the female fetus in comparison to the male fetus. Birth weight of the female fetuses were also higher than that of male fetus. We found that there are very strong associations between cord leptin concentrations at delivery and birth weight, ponderal index of the baby, body mass index of the mothers with Type 2 DM. We also found that high leptin levels could represent an important feedback modulator of substrate supply and subsequently for adipose tissue status during late gestation or adipose tissue is the major determinant of circulating leptin levels.

Testosterone, obesity and insulin resistance in young males: evidence for an association between gonadal dysfunction and insulin resistance during puberty

OBJECTIVE

To assess the relationships among obesity, insulin sensitivity, and testosterone in pubertal boys.

PARTICIPANTS

This study included 20 lean, obese, and type 2 diabetic (T2DM) males, the majority of whom underwent a hyperinsulinemic-euglycemic clamp (n=16).

METHODS

Glucose disposal (M value), serum testosterone, and body mass index (BMI) z-score were measured. Differences in testosterone were evaluated by group (lean vs. obese vs. T2DM), while regression was performed to evaluate the relationships among testosterone, obesity and insulin sensitivity.

RESULTS

Controlling for Tanner stage, testosterone concentration was significantly lower in obese (p=0.02) and T2DM males (p=0.001) compared to lean males. Furthermore, M value was significantly associated with serum testosterone, even after controlling for BMI and Tanner stage.

CONCLUSIONS

These data suggest that obese adolescent boys have lower serum testosterone than controls of the same Tanner stage, and echo the data in adult males associating obesity and insulin resistance with hypogonadism.

Sex dimorphisms in inflammatory markers and adiposity in African-American youth

OBJECTIVE

There are demonstrated sex differences in the association between adiposity and inflammation in adults. Our aim was to determine sex differences in inflammatory markers and in the association between adiposity and inflammation in a sample of African-American adolescents.

METHODS

Adiposity variables including body mass index (BMI), waist circumference, weight, total fat, trunk fat, and inflammatory markers including interleukin-6 (IL-6), leptin, monocyte chemotactic protein 1 (MCP1), C-reactive Protein (CRP), adiponectin were examined in 166 (53% female) African-American adolescents, aged 14-19 years. Total fat and trunk fat were measured using Dual-Energy X-ray Absorptiometry (DXA).

RESULTS

Results revealed males had higher weight (p=0.01); females had higher BMI, trunk fat, and total fat (p's <0.01). With inflammation, males had higher MCP1 (p=0.024); females had higher leptin (p<0.001), adiponectin (p=0.006), and IL-6 (p=0.026). Partial correlations in males indicated associations of adiposity variables with leptin, adiponectin (all p's <0.01), and CRP (p<0.05); in females, leptin, CRP, and IL-6 were associated with adiposity variables (all p's <0.05). multiple regression analyses revealed female adiposity variables predicted CRP, (R(2)=0.254), IL-6 (R(2)=0.167), and MCP1 (R(2)=0.220). Adiposity variables in males predicted lower adiponectin (R(2)=0245). For both, leptin was predicted by adiposity (males R(2)=0.420 and females R(2)=0.410).

CONCLUSIONS

Data indicate clear sex dimorphisms in the associations between inflammatory markers and adiposity in African-American adolescents, suggesting that preventive measures and treatments for adolescent obesity may need to be sex-specific.

Brief report: plasma leptin levels are elevated in autism: association with early onset phenotype?

There is evidence of both immune dysregulation and autoimmune phenomena in children with autism spectrum disorders (ASD). We examined the hormone/cytokine leptin in 70 children diagnosed with autism (including 37 with regression) compared with 99 age-matched controls including 50 typically developing (TD) controls, 26 siblings without autism, and 23 children with developmental disabilities (DD). Children with autism had significantly higher plasma leptin levels compared with TD controls (p<.006). When further sub-classified into regression or early onset autism, children with early onset autism had significantly higher plasma leptin levels compared with children with regressive autism (p<.042), TD controls (p<.0015), and DD controls (p<.004). We demonstrated an increase in leptin levels in autism, a finding driven by the early onset group.

Influence of serum leptin on weight and body fat growth in children at high risk for adult obesity

OBJECTIVE

Our objective was to examine serum leptin prospectively as a predictor of weight and body fat growth in children at high risk for adult obesity. We hypothesized that leptin measurements would be positively associated with increased growth of adipose tissue because children with high baseline leptin for their body fat mass have greater leptin resistance and thus would have greater susceptibility to weight gain.

METHODS

Children ages 6-12 yr at high risk for adult obesity because of early-onset childhood overweight and/or parental overweight were recruited from 1996-2004. Growth in body mass index (BMI) was studied in 197 children, and growth in total body fat mass was examined in 149 children over an average follow-up interval of 4.4 yr (range, 1-8 yr). Longitudinal analyses accounted for sex, race, socioeconomic status, initial body composition, age, skeletal age, and physical activity and included all available interim visits for each individual so that a total of 982 subject visits were included in the analysis.

RESULTS

At baseline, 43% of children studied were overweight (BMI > or = 95th percentile); during follow-up, an additional 14% became overweight. Independent of initial body composition, baseline leptin was a statistically significant positive predictor of increased BMI (P = 0.0147) and increased total body fat mass (P < 0.007).

CONCLUSIONS

High serum leptin, independent of body fat, may be an indicator of increased leptin resistance, which predisposes children at high risk for adult obesity to somewhat greater growth in weight and body fat during childhood.

The utility of serum leptin and follicular fluid leptin, estradiol, and progesterone levels during an in vitro fertilization cycle

PURPOSE

To prospectively evaluate serum and follicular fluid leptin, estradiol, and progesterone levels during in vitro fertilization.

METHODS

Prospective observational study measuring serum levels at six points during the IVF cycle and follicular fluid at the time of retrieval.

RESULTS

Serum leptin and estradiol levels both significantly increased for the individual patients during the IVF stimulation process. None of the leptin levels differed based on pregnancy outcome. BMI significantly correlated with all leptin levels. Follicular fluid estradiol correlated with serum estradiol only in pregnant patients (r = 0.97, p<0.01) and was unrelated in non-pregnant patients (r=-0.15, p=0.81).

CONCLUSION

Serum and follicular leptin levels are highly correlated. Leptin levels increase during the IVF cycle and vary between patients based on maternal BMI, but do not correlate with other serum hormone levels or pregnancy outcome. Pregnancy outcome success was reflected in the relationship between follicular fluid and serum levels of estradiol, independent of leptin levels.

Leptin and its emerging role in children and adolescents

Leptin is an adipocyte-secreted hormone which plays a key role in energy homeostasis. Recent “proof of concept” studies involving leptin administration to humans support its critical role in regulating energy homeostasis, neuroendocrine and immune function as well as insulin resistance in states of energy/ caloric deprivation. Moreover, interventional studies in leptin deficient children and observational studies in normal girls and boys support a role for leptin as a permissive factor for the initiation of puberty in children. The potential clinical usefulness of leptin in several disease states in children and adolescents, including hypothalamic amenorrhea, eating disorders and syndromes of insulin resistance is still under investigation.

Onset of breast and pubic hair development in 1231 preadolescent Lithuanian schoolgirls

BACKGROUND

Correct staging of puberty is essential in order to differentiate different pathologies, as various components of the endocrine system influence breast, pubic, and axillary hair development.

AIMS

To determine the current timing of adrenarche and breast development in Lithuanian preadolescent schoolgirls.

METHODS

Cross-sectional study of 1231 schoolgirls aged 7.0-11.6 years. Puberty was staged according to the method of Tanner. Mean age at entry into each pubertal stage was calculated by probit analysis.

RESULTS

Of the 255 girls aged 7 years, two had premature adrenarche (0.8%) and one premature thelarche (0.4%). Mean age of onset of pubic/axillary hair development was 11.0 years, and for breast development (Stage 2) 10.2 years. Breast Stage 3 development was attained at 11.3 years and Stage 4 at 13.9 years. Mean BMI, height, weight, and systolic blood pressure SD scores were higher in pubertal than in prepubertal girls. Skinfold thickness was also significantly higher in girls with isolated adrenarche than in prepubertal girls. The increase in BMI and weight resulted from an increase in body fat as evidenced by measures of subscapular and triceps skinfold thickness. Girls with only signs of adrenarche or thelarche did not differ from each other from the anthropometric standpoint.

CONCLUSIONS

Premature thelarche and premature adrenarche were relatively uncommon in this population. Pubertal onset was slightly earlier than the UK Tanner standards and tended to occur in girls with a higher BMI.