| 2. |
- Gianfagna, Francesco, et al.
(författare)
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Understanding the Links among neuromedin U Gene, beta2-adrenoceptor Gene and Bone Health: An Observational Study in European Children.
- 2013
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8
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Tidskriftsartikel (refereegranskat)abstract
- Neuromedin U, encoded by the NMU gene, is a hypothalamic neuropeptide that regulates both energy metabolism and bone mass. The beta-2 adrenergic receptor, encoded by the ADRB2 gene, mediates several effects of catecholamine hormones and neurotransmitters in bone. We investigated whether NMU single nucleotide polymorphisms (SNPs) and haplotypes, as well as functional ADRB2 SNPs, are associated with bone stiffness in children from the IDEFICS cohort, also evaluating whether NMU and ADRB2 interact to affect this trait. A sample of 2,274 subjects (52.5% boys, age 6.2±1.8 years) from eight European countries, having data on calcaneus bone stiffness index (SI, mean of both feet) and genotyping (NMU gene: rs6827359, rs12500837, rs9999653; ADRB2 gene: rs1042713, rs1042714), was studied. After false discovery rate adjustment, SI was significantly associated with all NMU SNPs. rs6827359 CC homozygotes showed the strongest association (recessive model, Δ=-1.8, p=0.006). Among the five retrieved haplotypes with frequencies higher than 1% (range 2.0-43.9%), the CCT haplotype (frequency=39.7%) was associated with lower SI values (dominant model, Δ=-1.0, p=0.04) as compared to the most prevalent haplotype. A non-significant decrease in SI was observed in in ADRB2 rs1042713 GG homozygotes, while subjects carrying SI-lowering genotypes at both SNPs (frequency=8.4%) showed much lower SI than non-carriers (Δ=-3.9, p<0.0001; p for interaction=0.025). The association was more evident in preschool girls, in whom SI showed a curvilinear trend across ages. In subgroup analyses, rs9999653 CC NMU or both GG ADRB2 genotypes were associated with either lower serum calcium or β-CrossLaps levels (p=0.01). This study in European children shows, for the first time in humans, a role for NMU gene through interaction with ADRB2 gene in bone strength regulation, more evident in preschool girls.
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| 5. |
- Ojiambo, Robert, et al.
(författare)
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Validity of hip-mounted uniaxial accelerometry with heart-rate monitoring vs. triaxial accelerometry in the assessment of free-living energy expenditure in young children: the IDEFICS Validation Study
- 2012
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Ingår i: Journal of applied physiology (Bethesda, Md. : 1985). - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 113:10, s. 1530-1536
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Tidskriftsartikel (refereegranskat)abstract
- One of the aims of Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) validation study is to validate field measures of physical activity (PA) and Energy expenditure (EE) in young children. This study compared the validity of uni-axial accelerometry with heart-rate (HR) monitoring vs. tri-axial accelerometry against doubly labeled water (DLW) criterion method for assessment of free-living EE in young children. 49 European children (25 female, 24 male) aged 4-10 years (mean age 7 ± 2 years) were assessed by uni-axial ActiTrainer with HR, uni-axial 3DNX and tri-axial 3DNX accelerometry. Total energy expenditure (TEE) was estimated using DLW over a 1 week period. The longitudinal axis of both devices and tri-axial 3DNX counts per minute (CPM) were significantly (P<0.05) associated with physical activity level (PAL) (r = 0.51 ActiTrainer, r = 0.49 uni-axial-3DNX and r = 0.42 tri-axial ∑3DNX). 86% of the variance in TEE could be predicted by a model combining body mass (Partial r(2) = 71%; P<0.05), CPM-ActiTrainer (Partial r(2) = 11%; P<0.05) and difference between HR at moderate and sedentary activities (ModHR - SedHR; Partial r(2) = 4%; P<0.05) The standard error (S.E) of TEE estimate for ActiTrainer and 3DNX models ranged from 0.44-0.74 MJ/d or approximately 7-11% of the average TEE. The S.E of activity-induced energy expenditure (AEE) model estimates ranged from 0.38-0.57 MJ/d or 24-26% of the average AEE. It is concluded that the comparative validity of hip-mounted uni-axial and tri-axial accelerometers for assessing PA and EE is similar.
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