Fetuin B links vitamin D deficiency and pediatric obesity: Direct negative regulation by vitamin D.

Vitamin D (VD) deficiency (VDD) correlates to obesity, with VD a recognized mediator of metabolic diseases. From a previous proteomic study identifying adiponectin as a link between VDD and pediatric obesity, herein we analysed another protein (SSP2301) increased with VDD. A focused 2D-electrophoretic analysis identified 4 corresponding plasma proteins, with one predicted to be fetuin B (FETUB). FETUB was studied due to its emerging role in metabolic diseases and cytogenetic location (3q27.3) with adiponectin. Results were confirmed in obese children, where plasma FETUB was higher with VDD. A direct effect by 1α,25-(OH)2D3 on hepatocellular FETUB synthesis was observed, with a time and dose dependent reduction. Further, we demonstrated the VD-receptor (VDR) is key, with FETUB "released" with VDR silencing. Finally, VD supplementation (6weeks) to juvenile mice fed a standard diet, reduced plasma FETUB. Only at 22weeks did liver FETUB correspond to plasma FETUB, highlighting the contribution of other VD-responsive tissues. Overall, FETUB is a key protein linking VDD to pediatric obesity. With an emerging role in metabolic diseases, we demonstrate that VD/VDR directly regulate FETUB.

Pediatric obesity and vitamin D deficiency: a proteomic approach identifies multimeric adiponectin as a key link between these conditions.

Key circulating molecules that link vitamin D (VD) to pediatric obesity and its co-morbidities remain unclear. Using a proteomic approach, our objective was to identify key molecules in obese children dichotomized according to 25OH-vitamin D (25OHD) levels. A total of 42 obese children (M/F = 18/24) were divided according to their 25OHD3 levels into 25OHD3 deficient (VDD; n = 18; 25OHD<15 ng/ml) or normal subjects (NVD; n = 24; >30 ng/ml). Plasma proteomic analyses by two dimensional (2D)-electrophoresis were performed at baseline in all subjects. VDD subjects underwent a 12mo treatment with 3000 IU vitamin D3 once a week to confirm the proteomic analyses. The proteomic analyses identified 53 "spots" that differed between VDD and NVD (p<0.05), amongst which adiponectin was identified. Adiponectin was selected for confirmational studies due to its tight association with obesity and diabetes mellitus. Western Immunoblot (WIB) analyses of 2D-gels demonstrated a downregulation of adiponectin in VDD subjects, which was confirmed in the plasma from VDD with respect to NVD subjects (p<0.035) and increased following 12mo vitamin D3 supplementation in VDD subjects (p<0.02). High molecular weight (HMW) adiponectin, a surrogate indicator of insulin sensitivity, was significantly lower in VDD subjects (p<0.02) and improved with vitamin D3 supplementation (p<0.042). A direct effect in vitro of 1α,25-(OH)2D3 on adipocyte adiponectin synthesis was demonstrated, with adiponectin and its multimeric forms upregulated, even at low pharmacological doses (10(-9) M) of 1α,25-(OH)2D3. This upregulation was paralleled by the adiponectin interactive protein, DsbA-L, suggesting that the VD regulation of adiponectin involves post-transciptional events. Using a proteomic approach, multimeric adiponectin has been identified as a key plasma protein that links VDD to pediatric obesity.

Functional SNPs within the intron 1 of the PROP1 gene contribute to combined growth hormone deficiency (CPHD).

CONTEXT: Mutations within the PROP1 gene represent one of the main causes of familial combined pituitary hormone deficiency (CPHD). However, most of the cases are sporadic with an unknown genetic cause. OBJECTIVE: The aim of this study was the search for low penetrance variations within and around a conserved regulatory element in the intron 1 of PROP1, contributing to a multifactorial form of the disease in sporadic patients. METHODS AND PATIENTS: A fragment of 570 bp encompassing the conserved region was sequenced in 107 CPHD patients and 294 controls, and an association study was performed with the four identified variants, namely c.109+435G>A (rs73346254), c.109+463C>T (rs4498267), c.109+768C>G (rs4431364), and c.109+915_917ins/delTAG (rs148607624). The functional role of the associated polymorphisms was evaluated by luciferase reporter gene expression analyses and EMSA. RESULTS: A statistically significant increased frequency was observed in the patients for rs73346254A (P = 5 × 10(-4)) and rs148607624delTAG (P = 0.01) alleles. Among all the possible allele combinations, only the haplotype bearing both risk alleles showed a significantly higher frequency in the patients vs. controls (P = 4.7 × 10(-4)) and conferred a carrier risk of 4.19 (P = 1.2 × 10(-4)). This haplotype determined a significant decrease of the luciferase activity in comparison with a basal promoter and the other allelic combinations in GH4C and MCF7 cells (P = 4.6 × 10(-6); P = 5.5 × 10(-4), respectively). The EMSA showed a differential affinity for nuclear proteins for the alternative alleles of the two associated variations. CONCLUSIONS: Variations with a functional significance conferring susceptibility to CPHD have been identified in the PROP1 gene, indicating a multifactorial origin of this disorder in sporadic cases.

Hypopituitarism in childhood and adolescence following traumatic brain injury: the case for prospective endocrine investigation.

Pituitary dysfunction is now well recognised after traumatic brain injury (TBI) in adults; however, little except anecdotal evidence is known about this potential complication in childhood and adolescence. Histopathological evidence exists for both hypothalamic and pituitary damage, but few data specific to children have been published. We review the available paediatric data, which shows that after both mild and severe TBI, hypopituitarism may occur, with GH and gonadotrophin deficiencies appearing to be most common. Precocious puberty has also been documented. Road-traffic accidents, falls, sport and child abuse are the most common aetiological factors for paediatric TBI. There are no published data on the incidence or prevalence, neither within a population of children with TBI, of hypopituitarism, nor on its natural history or response to hormone replacement. We urge paediatric endocrinologists, in collaboration with adult endocrinologists, to perform formal prospective research studies in patients suffering from TBI to clarify these questions.

Diagnosis of GH deficiency in the transition period: accuracy of insulin tolerance test and insulin-like growth factor-I measurement.

OBJECTIVE: A consensus exists that severe growth hormone deficiency (GHD) in adults is defined by a peak GH response to insulin-induced hypoglycemia (insulin tolerance test, ITT) of less than 3 microg/l based on a cohort of subjects with a mean age of 45 years. DESIGN AND METHODS: By considering one of the following two criteria for the diagnosis of probable permanent GHD, i.e. the severity of GHD (suggested by the presence of multiple pituitary hormone deficiencies (MPHD)) or the magnetic resonance (MR) imaging identification of structural hypothalamic-pituitary abnormalities, 26 patients (17 males, 9 females, mean age 20.8 +/- 2.3 years, range 17-25 years) were selected for re-evaluation of the GH response to ITT and their IGF-I concentration. Eight subjects had isolated GHD (IGHD) and 18 had MPHD. Normative data for peak GH were obtained after ITT in 39 healthy subjects (mean age 21.2 +/- 4.4 years, range 15.1-30.0 years) and the reference range for IGF-I was calculated using normative data from 117 healthy individuals. RESULTS: Mean peak GH response to ITT was significantly lower in the 26 patients (1.8+/-2.0 microg/l, range 0.1-6.1 microg/l) compared with the 39 controls (18.5 +/- 15.5 microg/l, range 6.1-84.0 microg/l; P < 0.0001). One subject with septo-optic dysplasia had a peak GH response of 6.1 microg/l that overlapped the lowest peak GH response obtained in normal subjects. There was an overlap for IGF-I SDS between subjects with IGHD and MPHD, as well as with normal controls. The diagnostic accuracy of a peak GH response of 6.1 microg/l showed a 96% sensitivity with 100% specificity. The maximum diagnostic accuracy with IGF-I SDS was obtained with a cut-off of -1.7 SDS (sensitivity 77%, specificity 100%) while an IGF-I < or = - 2.0 SDS showed a sensitivity of 62%. CONCLUSION: Our data show that the cut-off value of the peak GH response to ITT of less than 3 microg/l or 5 microg/l and of IGF-I of less than -2.0 SDS are too restrictive for the diagnosis of permanent GH deficiency in the transition period. We suggest that permanent GHD could be investigated more accurately by means of an integrated analysis of clinical history, the presence of MPHD, IGF-I concentration and the MR imaging findings of structural hypothalamic-pituitary abnormalities.