High prevalence of genu varum/valgum in European children with low vitamin D status and insufficient dairy products/calcium intakes.

Objective: The prevalence of lower limb deformities physiologically decreases after 5 years of age. It remains high in some tropical and subtropical regions where it has been associated with severe vitamin D deficiency, low calcium/milk intakes, malnutrition, and/or fluoride overexposure. Very little data is available in apparently healthy Caucasian children and adolescents.

Adverse interaction of low-calcium diet and low 25(OH)D levels on lumbar spine mineralization in late-pubertal girls.

No consensus has been reached on the serum 25-hydroxyvitamin D [25(OH)D] levels required to ensure optimal bone health around menarche. We searched for a possible interaction of 25(OH)D levels and calcium intake on lumbar spine mineralization and on biologic features of bone metabolism in healthy late-pubertal girls. Lumbar spine parameters (ie, area, mineral content, and density) and calcium intake were evaluated in 211 healthy white adolescent girls at pubertal stages IV-V (11 to 16.

Growth, calcium status and vitamin D receptor (VDR) promoter genotype in European children with normal or low calcium intake.

Calcium homeostasis and bone metabolism require the vitamin D receptor (VDR) to function properly, as evidenced in patients and transgenic mice with VDR mutations. We have shown that (A/G) polymorphism at the -1012 locus of the VDR promoter (rs4516035) is frequent in European populations, may influence VDR expression, is associated with height in French adolescent girls, and is associated with their lumbar spine mineral density in case of insufficient milk intake. Here, an association study was performed in a cohort of Moldovan children and adolescents, living at latitude similar to the first cohort but receiving a cereal-based diet with very low milk/dairy product intakes.

PHEX analysis in 118 pedigrees reveals new genetic clues in hypophosphatemic rickets.

Familial hypophosphatemic rickets is a rare disease, which is mostly transmitted as an X-linked dominant trait, and mutations on the phosphate regulating gene with homologies to endopeptidases on the X-chromosome (PHEX) gene are responsible for the disease in most familial cases. In this study we analyzed PHEX in a large cohort of 118 pedigrees representing 56 familial cases and 62 sporadic cases. The high-resolution melting curves technique was tested as a screening method, along with classical sequencing.

Vitamin D receptor genotype in hypophosphatemic rickets as a predictor of growth and response to treatment.

Context: Treatment of X-linked hypophosphatemic rickets improves bone mineralization and bone deformities, but its effect on skeletal growth is highly variable.

Objective: Genetic variants in the promoter region of the vitamin D receptor (VDR) gene may explain the response to treatment because this receptor mediates vitamin D action.

Design: We studied the VDR promoter haplotype structure in a large cohort of 91 patients with hypophosphatemic rickets including 62 patients receiving 1alpha-hydroxyvitamin D3 derivatives and phosphates from early childhood on.

Milk, rather than other foods, is associated with vertebral bone mass and circulating IGF-1 in female adolescents.

Summary: Low calcium intake hampers bone mineral acquisition in adolescent girls. This study explores dietary calcium sources and nutrients possibly associated with vertebral mass. Milk intake is not influenced by genetic variants of the lactase gene and is positively associated with serum IGF-1 and with lumbar vertebrae mineral content and density.

[Maternal vitamin D status in Martinique].

Objectives: Evaluate vitamin D supplementation and vitamin D status during normal pregnancy in Martinique, a Caribbean region with sufficient sunshine for endogenous vitamin D production all year around; and "to validate" or not the necessity of supplementing pregnant women with vitamin D in Martinique.

Patients And Methods: A prospective evaluation of their vitamin D status was performed over a winter four-month period on 63 healthy women seen at term delivery. Maternal blood sampling for assays of serum 25 (OH)D, calcium, phosphates and alkaline phosphatase activity was realized in working room.

Two single-nucleotide polymorphisms in the human vitamin D receptor promoter change protein-DNA complex formation and are associated with height and vitamin D status in adolescent girls.

Numerous association studies have dealt with single-nucleotide polymorphisms (SNPs) in coding and intronic regions of the human vitamin D receptor (hVDR) gene. We have hypothesized that phenotypic traits may also be associated with variations in VDR expression due to the presence of SNPs in promoter regions. In this work, we have studied two SNPs located 1521 bp (G/C) and 1012 bp (A/G) upstream of the transcriptional start site of the main human VDR gene promoter.

[Prevention of child and adolescent vitamin D deficiency. II. Validation of a decision-making abacus based on sun exposure and vitamin D intakes].

Objectives: Rickets can still be observed among children and adolescents living in Europe, and a significant proportion of healthy children and adolescents presents serum 25-hydroxyvitamin D (25-(OH)D) values below the threshold indicating an insufficient vitamin D status. We have previously proposed detecting at risk individuals with a decision-making abacus based on questionnaires assessing calcium and vitamin D intakes and vitamin D production via sun exposure.

Methods: We tested the validity of this detection by receiver operating characteristic (ROC) analysis, using, as the main outcome measure, the serum 25-(OH)D values measured at the time of questionnaires presentation.

Possible involvement of pregnane X receptor-enhanced CYP24 expression in drug-induced osteomalacia.

Vitamin D controls calcium homeostasis and the development and maintenance of bones through vitamin D receptor activation. Prolonged therapy with rifampicin or phenobarbital has been shown to cause vitamin D deficiency or osteomalacia, particularly in patients with marginal vitamin D stores. However, the molecular mechanism of this process is unknown.

Changes in 1,25-(OH)2D3 synthesis and its receptor expression in spleen cell subpopulations of mice infected with LPBM5 retrovirus.

This study examines the influence of chronic retroviral infection of mice with a LPBM5 virus mixture on the paracrine system involving immune cells and 1,25-(OH)2D3 in the spleen. Plasma ionized calcium, 25-(OH)D and 1,25-(OH)2D of infected mice were unchanged. In contrast, the specific binding of 1,25-(OH)2D3 to spleen cytosol and the number of monocyte/macrophages expressing 1,25-(OH)2D3 receptors (VDR) were markedly increased.

Subclinical vitamin D deficiency in neonates: definition and response to vitamin D supplements.

To determine the biological criteria for neonatal vitamin D deficiency, serum 25-hydroxyvitamin D (calcidiol), parathyroid hormone (PTH), calcium, phosphates, and alkaline phosphatase (ALP) activity were measured during the winter-spring period in 80 healthy neonates and their mothers 3-6 d after delivery. A longitudinal 3-mo survey of the serum biology of 52 of these neonates consuming formula was also performed to test the influence of their neonatal vitamin D status on the effects of two oral ergocalciferol supplements (500 and 1000 IU or 12.5 and 25 micrograms/d).

[Fortified milk and supplements of oral vitamin D. Comparison of the effect of two doses of vitamin D (500 and 1,000 UI/d) during the first trimester of life].

Background: Administration of oral vitamin D supplements has been the usual strategy used in France for the prevention of rickets. But this strategy needs reevaluation since the fortification of infant formulas with vitamin D is authorized in this country. We report the effects of oral daily supplements of vitamin D on the calcium metabolism and vitamin D status of infants receiving or not fortified milk during the first trimester of life.