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Francesco Chiarelli and Maria Loredana Marcovecchio

Childhood obesity is a significant health problem that has reached epidemic proportions around the world and is associated with several metabolic and cardiovascular complications. Insulin resistance is a common feature of childhood obesity and is considered to be an important link between adiposity and the associated risk of type 2 diabetes and cardiovascular disease. Insulin resistance is also a key component of the metabolic syndrome, and its prevalence in the paediatric population is increasing, particularly among obese children and adolescents. Several factors are implicated in the pathogenesis of obesity-related insulin resistance, such as increased free fatty acids and many hormones and cytokines released by adipose tissue.

Valid and reliable methods are essential to assess the presence and the extent of insulin resistance, the associated risk factors and the effect of pharmacological and lifestyle interventions. The two most common tests to assess insulin resistance are the hyperinsulinemic euglycemic clamp and the frequently sampled i.v. glucose tolerance test utilizing the minimal model. However, both these tests are not easily accomplished, are time consuming, expensive and invasive. Simpler methods to assess insulin resistance based on surrogate markers derived from an oral glucose tolerance test or from fasting insulin and glucose levels have been validated in children and adolescents and widely used.

Given the strong association between obesity, insulin resistance and the development of metabolic syndrome and cardiovascular disease, prevention and treatment of childhood obesity appear to be essential to prevent the development of insulin resistance and the associated complications.

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Alberto Verrotti, Melissa Laus, Alessandra Scardapane, Emilio Franzoni and Francesco Chiarelli

Objective

This study evaluates the effects of long-term carbamazepine (CBZ) and valproate acid (VPA) therapy on thyroid function in epileptic children.

Design

A prospective study performed in 32 newly diagnosed pediatric patients, subdivided into two groups: 18 patients treated with CBZ and 14 patients treated with VPA. Thirty-two sex- and age- matched subjects served as controls.

Methods

Serum TSH, thyroxine (T4), triiodothyronine (T3), free thyroxine (fT4), free triiodothyronine (fT3), thyroid peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (TG-Ab) were evaluated at baseline and at the 3rd, 6th, and 12th month in all patients and in the control group. A TRH stimulation test was performed in all epileptic patients at baseline and at the 3rd, 6th, and 12th month evaluations while in controls only baseline assessment was carried out.

Results

At baseline evaluation, thyroid function was normal in all epileptic children. After 3 months, CBZ-treated patients showed serum T4 and fT4 levels significantly lower than baseline evaluation and control subjects. Serum T4 and fT4 concentrations were unaffected by VPA monotherapy. Serum T3 and fT3 were normal in both CBZ-treated and VPA-treated patients. TRH test was normal in all patients. At 6th and 12th month evaluations, the same alterations were present in CBZ-treated patients while thyroid function remained normal in VPA-treated patients. TRH test responses were normal in all epileptic patients. TPO-Ab and TG-Ab were always absent in all patients.

Conclusions

Our data suggest that VPA monotherapy does not alter thyroid hormones. On the contrary, alterations of thyroid hormones occur in CBZ-treated children. However, the patients are euthyroid and thyroid hormone alterations are not associated with clinical or subclinical hypothyroidism.

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Alberto Verrotti, Alessandra Scaparrotta, Cristina Olivieri and Francesco Chiarelli

In this review, we will try to analyze the possible coexistence between epilepsy or seizures and type 1 diabetes mellitus (T1DM), in order to establish if there is more than a casual association, and to investigate possible mechanisms underlying this link. Anti-glutamic acid decarboxylase antibodies (GAD-Abs) have been associated with T1DM and a great number of neurological diseases such as epilepsy. Epilepsy can be a feature of a large variety of autoimmune or inflammatory disorders. GAD-Abs can have a role at the basis of the possible link between epilepsy and T1DM, although their real pathogenetic mechanism in neurological diseases is still unknown. Metabolic conditions such as hypoglycemia and hyperglycemia, common problems in diabetic patients, may be also implicated, even if their underlying mechanism is minimally understood.

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Lucia Pacifico, Eleonora Poggiogalle, Francesco Costantino, Caterina Anania, Flavia Ferraro, Francesco Chiarelli and Claudio Chiesa

Background

Ghrelin, a peptide mainly derived from the stomach, plays a pivotal role in the regulation of food intake, energy metabolism, and storage, as well as in insulin sensitivity. Ghrelin circulates in acylated (A-Ghr) and nonacylated (NA-Ghr) forms, and their potential differential associations with insulin resistance (IR) in childhood obesity remain undefined.

Objective

We investigated the associations of ghrelin forms with IR in normal weight and obese children and the impact of metabolic syndrome (MS) on their plasma values.

Design

A total of 210 children in four subgroups of normal weight/obese children with and without components of MS were studied. Fasting blood glucose, insulin, lipid profile, and acylated and total ghrelin were examined. IR was determined by a homeostasis model assessment (HOMA) of IR.

Results

In the entire population, plasma insulin and HOMA-IR were associated negatively with T-Ghr and NA-Ghr, but positively with the ratio of A/NA-Ghr after adjustment for age, gender, and Tanner stage. Obese metabolically abnormal children had lower T-Ghr and NA-Ghr, but comparable A-Ghr and a higher A/NA-Ghr ratio than obese metabolically normal subjects. Compared with lean healthy children, lean metabolically abnormal subjects had higher A-Ghr and the A/NA-Ghr ratio, but comparable T-Ghr and NA-Ghr. A multiple regression analysis showed that A-Ghr and the A/NA-Ghr ratios were positively associated with HOMA-IR, independent of age, gender, Tanner stage, and body mass index (or waist circumference) and other components of MS.

Conclusions

A-Ghr excess may negatively modulate insulin action in obese and nonobese children, and may contribute to the association of IR and MS.

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Valentina Chiavaroli, Marco Liberati, Francesco D'Antonio, Fabio Masuccio, Rita Capanna, Alberto Verrotti, Francesco Chiarelli and Angelika Mohn

Objective

GNRH analog (GNRHa) therapy has not been supported by beneficial effects on adult stature in girls with early puberty. Furthermore, an increased prevalence of polycystic ovary syndrome (PCOS) has been described in girls treated for central precocious puberty. Women with PCOS are at increased risk of cardiometabolic dysfunctions and infertility. Our aim was to assess GNRHa effectiveness on reaching adult stature and the risk of PCOS in girls with early puberty.

Design

Longitudinal study of GNRHa-treated and GNRHa-untreated girls at baseline and at final height.

Methods

Twenty-five GNRHa-treated girls and 55 controls were compared. Insulin resistance (IR; homeostasis model assessment of IR (HOMA-IR) and glucose-to-insulin ratio (G/I)), the effect of GNRHa on final height, and the prevalence of PCOS were assessed.

Results

In GNRHa-treated girls, no significant difference was found between predicted final height and final height, whereas a significant difference was detected in untreated girls (P=0.0001). At final height, GNRHa-treated girls showed higher HOMA-IR and lower G/I (P=0.03 for both) as well as higher DHEAS and androstenedione levels (P=0.02 and P=0.01 respectively) than untreated girls. The prevalence of PCOS and hyperandrogenemia was significantly higher in GNRHa-treated adolescents than in untreated adolescents (36 and 14.5% respectively, P=0.04; 56 and 23.6% respectively, P=0.01). Finally, gonadotropin-suppressive therapy was significantly related to PCOS during adolescence (P=0.03).

Conclusions

In girls with early puberty, GNRHa therapy is associated with the achievement of predicted final height; nevertheless, this treatment seems to act as an independent risk factor for the development of PCOS already during adolescence.

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Fiorella Galluzzi, Stefano Stagi, Roberto Salti, Sonia Toni, Elisabetta Piscitelli, Gabriele Simonini, Fernanda Falcini and Francesco Chiarelli

Objective: Children and adolescents with type 1 (insulin-dependent) diabetes mellitus (T1DM) show several impairment of bone metabolism and structure, resulting in a higher risk of decreased bone mass and its related complications later in life. Alterations of the nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) system have been implicated in several metabolic bone diseases characterized by increased osteoclast differentiation and activation and enhanced bone resorption.

Design: We aimed to assess OPG levels and to investigate the possible relation between OPG levels, bone status and glycemic control in a group of prepubertal children with T1DM without microvascular complications.

Methods: Twenty-six prepubertal T1DM children (median age 9.9 years, range 4.1–13.1 years) were studied. In all patients, serum OPG, hemoglobin (Hb)A1c, parathyroid hormone (PTH) and 25-dihy-droxyvitamin D (25-D) levels were evaluated. Bone quality was determined by measuring the attenuation of ultrasound waves by bone (broadband ultrasound attenuation (BUA)) at the calcaneal site. The data were compared with those of a group of 45 age-, sex-and body-size-matched healthy children.

Results: Children with T1DM showed a reduced Z-score BUA in comparison with the control group (Student’s t-test, P < 0.0001). Plasma OPG levels were significantly higher in diabetic children than in controls (Student’s t-test, P < 0.0001). In T1DM children, Z-score BUA values displayed a significant correlation with OPG (Student’s t-test, r = −0.62; P = 0.001), and HbA1c (r = −0.59; P = 0.007). OPG levels were significantly correlated with HbA1c (r = 0.56; P = 0.008). In a multiple regression analysis including age, duration of diabetes, physical activity, calcium intake, mean HbA1c and Z-score BUA, only HbA1c significantly predicted serum OPG levels (beta 0.67; P = 0.003).

Conclusions: Prepubertal children with T1DM have a significant increase of OPG levels. OPG serum concentrations are correlated to calcaneal BUA and HbA1c values. OPG could be a new marker of reduced bone mass in children with T1DM.

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Tommaso de Giorgis, M Loredana Marcovecchio, Ilaria Di Giovanni, Cosimo Giannini, Valentina Chiavaroli, Francesco Chiarelli and Angelika Mohn

Objective

To investigate whether there is an association of the triglyceride-to-HDL cholesterol (TG:HDL-C) ratio with cardiovascular risk factors and early signs of vascular damage in obese prepubertal children.

Design and methods

In 50 obese (27 boys, 7.8±1.4 years) and 37 normal-weight (20 boys; 7.3±1.5 years) prepubertal children, anthropometric measurements, oxidative stress markers (urinary isoprostanes (PGF2α (prostaglandin F2α)), soluble receptor for advanced glycation end-products (sRAGE)) and insulin sensitivity (homeostasis model assessment of insulin resistance (HOMA-IR) and whole-body insulin sensitivity index (WBISI)) were evaluated. Lipids profile was assessed and the TG:HDL-C ratio was calculated. In addition, high-resolution ultrasound was performed to assess carotid intima-media thickness (cIMT).

Results

Obese children showed significantly higher values of the TG:HDL-C ratio (1.9±1.1 vs 1.2±0.6, P=0.002) compared with controls. After dividing the population in tertiles of the TG:HDL-C ratio (<1.04, 1.04–1.67, >1.67), cIMT (P=0.0003), and HOMA-IR (P=0.0001) progressively increased from the lower to the upper tertile, whereas WBISI (P=0.0003) and sRAGE (P=0.05) progressively decreased. In a regression model, the TG:HDL ratio was significantly and positively associated with cIMT (r=0.493; P=0.0005). A cutoff point for TG:HDL-C ratio of 1.12 had 81% sensitivity and 49% specificity in the identification of children with cIMT values in the upper quartile (Area under the curve values from receiver operating characteristic curves=0.633±0.065, P=0.045).

Conclusion

This study confirms the reliability of the TG:HDL-C ratio as a useful marker of cardiovascular risk. Interestingly, our results underline that the TG:HDL-C ratio is directly related with early signs of vascular damage already present in prepubertal children.

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Stefano Stagi, Elisabetta Lapi, Eleonora Gambineri, Cristina Manoni, Maurizio Genuardi, Gloria Colarusso, Camilla Conti, Francesco Chiarelli, Maurizio de Martino and Chiara Azzari

Introduction

Although hypoparathyroidism with hypocalcaemia is one of the most frequent clinical features of monoallelic microdeletion of chromosome 22q11 (22q11DS), bone mass and metabolism have not yet been assessed in these patients.

Design

This study aimed to evaluate bone mass and metabolism in a cohort of patients, both children and adults, with 22q11DS.

Methods

In twenty-eight patients with 22q11DS (median age 12.5, range 6.1–42.8 years), serum levels of ionised and total calcium, phosphate, parathyroid hormone (PTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, osteocalcin and bone-specific alkaline phosphatase (BSAP), and urinary deoxypyridinoline concentrations were evaluated. In these patients, bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry (DXA) examination, and volumetric BMD (bone mineral apparent density (BMAD)) was calculated.

The data obtained from paediatric and adult patients were compared with two age-, sex- and body size-matched healthy subject control groups.

Results

Patients with 22q11DS showed a reduced BMAD Z-score compared with controls (P<0.001). These patients also had significantly lower ionised (P<0.001) and total calcium (P<0.05) levels as well as lower PTH levels (P<0.05), compared with the controls. In particular, children and young patients with 22q11DS had significantly lower serum osteocalcin levels (P<0.001), BSAP levels (P<0.001) and urinary deoxypyridinoline concentrations (P<0.001) than controls. These results were not confirmed in adults.

Finally, patients with hypoparathyroidism and/or hypocalcaemia at the time of the study showed significantly lower ionised (P<0.001) and total calcium levels (P<0.001), PTH levels (P<0.05), BSAP levels (P<0.001), osteocalcin levels (P<0.001) and urinary deoxypyridinoline concentrations (P<0.001), compared with patients without hypoparathyroidism and/or hypocalcaemia. Nonetheless, the BMAD Z-score did not show substantial differences between these two groups.

Conclusions

Subjects with 22q11DS have a significant reduction in bone mass that appears to be more severe in adults who have already attained peak bone mass than in children who are still growing. Therefore, we suggest a close monitoring of bone mass and metabolism in 22q11DS patients.

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Lotte B Nielsen, Kenneth B Ploug, Peter Swift, Cathrine Ørskov, Inger Jansen-Olesen, Francesco Chiarelli, Jens J Holst, Philip Hougaard, Sven Pörksen, Reinhard Holl, Carine de Beaufort, Steen Gammeltoft, Patrik Rorsman, Henrik B Mortensen and Lars Hansen

Group-author : on behalf of the Hvidøre Study Group

Objective: The ATP-dependent K+-channel (KATP) is critical for glucose sensing and normal glucagon and insulin secretion from pancreatic endocrine α- and β-cells. Gastrointestinal endocrine L- and K-cells are also glucose-sensing cells secreting glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotrophic polypeptide (GIP) respectively. The aims of this study were to 1) investigate the expression and co-localisation of the KATP channel subunits, Kir6.2 and SUR1, in human L- and K-cells and 2) investigate if a common hyperactive variant of the Kir6.2 subunit, Glu23Lys, exerts a functional impact on glucose-sensing tissues in vivo that may affect the overall glycaemic control in children with new-onset type 1 diabetes.

Design and methods: Western blot and immunohistochemical analyses were performed for expression and co-localisation studies. Meal-stimulated C-peptide test was carried out in 257 children at 1, 6 and 12 months after diagnosis. Genotyping for the Glu23Lys variant was by PCR-restriction fragment length polymorphism.

Results: Kir6.2 and SUR1 co-localise with GLP-1 in L-cells and with GIP in K-cells in human ileum tissue. Children with type 1 diabetes carrying the hyperactive Glu23Lys variant had higher HbA1C at bdiagnosis (coefficient = 0.61%, P = 0.02) and 1 month after initial insulin therapy (coefficient = 0.30%, P = 0.05), but later disappeared. However, when adjusting HbA1C for the given dose of exogenous insulin, the dose-adjusted HbA1C remained higher throughout the 12 month study period (coefficient = 0.42%, P = 0.03).

Conclusions: Kir6.2 and SUR1 co-localise in the gastrointestinal endocrine L- and K-cells. The hyperactive Glu23Lys variant of the KATP channel subunit Kir6.2 may cause defective glucose sensing in several tissues and impaired glycaemic control in children with type 1 diabetes.