An adequate vitamin D status is essential to optimize muscle strength. However, whether vitamin D directly reduces muscle fiber atrophy or stimulates muscle fiber hypertrophy remains subject of debate. A mechanism that may affect the role of vitamin D in the regulation of muscle fiber size is the local conversion of 25(OH)D to 1,25(OH)2 D by 1α-hydroxylase. Therefore, we investigated in a murin...

The competence of the duodenal 1ƒ¿, 25-(OH)2-D3 receptor system in embryonic chicks was studied in the reconstituted cytosol-chro matin system. The sucrose density gradient centrifugation following incubation of duodenal cytosol with 1x,25-dihydroxy-[3H]-vitamin D3 revealed that a cytosol 1x,25-dihydroxyvitamin D3 receptor existed in the duodenum of 18-day-old embryos. In the duodenum of 14-day...

Public health recommendations do not distinguish between vitamin D2 and vitamin D3, yet disagreement exists on whether these two forms should be considered equivalent. The objective of the present study was to evaluate the effect of a daily physiological dose of vitamin D2 or vitamin D3 on 25-hydroxyvitamin D (25(OH)D) status over the winter months in healthy adults living in Dunedin, New Zeala...

OBJECTIVE To investigate whether vitamin D deficiency is associated with high mean platelet volume (MPV) in pregnancies diagnosed with gestational diabetes mellitus (GDM) compared to healthy pregnancies. SUBJECTS AND METHODS This study included 200 pregnant women. 25-hydroxyvitamin D3(25(OH)D3) and MPV values were monitored between pregnant women with GDM and normal glucose metabolism. Correl...

25-Hydroxy-24-oxovitamin D3 (25(OH)24-oxo-D3), a metabolite of 25-hydroxyvitamin D3, has been chemically synthesized. The ultraviolet, mass, infrared, and proton nuclear magnetic resonance spectra of the 25(OH)24-oxo-D3 were identical with those of the natural product isolated from chick kidney incubates. The oxo compound showed biological activity similar to 24,25-dihydroxyvitamin D3 (24,25(OH...

BACKGROUND The three main vitamin D metabolizing enzymes, vitamin D3-25-hydroxylase (25-OHase, 25-hydroxylase), 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-OHase, 1alpha-hydroxylase) and 25-hydroxyvitamin D3-24-hydroxylase (24-OHase, 24-hydroxylase), have been described in malignant breast tissue. This in vitro study aimed to obtain more information regarding the regulation of these enzymes...

Pregnancy and lactation are associated with changes in vitamin D and calcium metabolism but the impact of these changes on vitamin D expenditure is unknown. We measured plasma 25(OH)D3 half-life with a stable-isotope tracer and investigated relationships with vitamin D metabolites in pregnant, lactating and 'non-pregnant, non-lactating' (NPNL) women. Vitamin D metabolites, vitamin D binding pro...