BACKGROUND The relative potency of 25-hydroxyvitamin D3 to vitamin D3 needs to be better defined so that food-composition tables can better reflect the true vitamin D nutritive value of certain foods. OBJECTIVE We performed a randomized, controlled intervention study in apparently healthy, free-living adults to investigate whether the intake of 25-hydroxyvitamin D3 is 5 times more potent in r...

There is considerable interest in developing highly selective dopamine (DA) D3 receptor ligands for a variety of mental health disorders. DA D3 receptors have been implicated in Parkinson's disease, schizophrenia, anxiety, depression, and substance use disorders. The most concrete evidence suggests a role for the D3 receptor in drug-seeking behaviors. D3 receptors are a subtype of D2 receptors,...

1,25-Dihydroxyvitamin D3, the hormonal form of vitamin D3, promotes the differentiation of HL-60 human promyelocytic leukemia cells into monocytes. Differentiation changes include the induction of phagocytosis, the initiation of nitroblue tetrazolium-reducing activity, and the appearance of nonspecific acid esterase. We have found that the 24-homo- and 26-homo-1,25-dihydroxyvitamin D3 and their...

Metabolites of vitamin D3 (D3) (cholecalciferol) are recognized as enzymatically formed chemicals in humans that can influence a wide variety of reactions that regulate a large number of cellular functions. The metabolism of D3 has been extensively studied, and a role for three different mitochondrial cytochrome P450s (CYP24A, CYP27A, and CYP27B1) has been described that catalyze the formation ...

Although some studies revealed a positive relationship between vitamin D3 deficiency and inflammatory markers, there have been also many studies that failed to find this relationship. The aim of this large scaled study is to determine the association between the level of plasma 25 hydroxy vitamin D3 [25-(OH) D3] and inflammatory markers in the general population without chronic kidney disease (...

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...

Constitutive Hedgehog (HH) signaling underlies several human tumors, including basal cell carcinoma (BCC). Recently, Bijlsma and colleagues reported a new biologic function for vitamin D3 in suppressing HH signaling in an in vitro model system. On the basis of that work, we have assessed effects of vitamin D3 on HH signaling and proliferation of murine BCCs in vitro and in vivo. We find that in...

The time course of in vivo metabolism of 24,25-dihydroxyvitamin D3 in rats has been examined. Several tissues were surveyed in an effort to discover new metabolites of 24,25-dihydroxyvitamin D3 and to estimate the concentrations of previously identified metabolites. Rapidly growing male rats were dosed with 24,25-dihydroxyvitamin D3 orally until plasma concentrations of 24,25-dihydroxyvitamin D...

The effect of 1,25-dihydroxyvitamin D3 on adenylate cyclase responsiveness was studied in the clonal osteogenic sarcoma cell line, UMR 106-06, which responds to several bone active hormones. 1,25-dihydroxyvitamin D3 treatment had no consistent effect on basal formation of cyclic AMP in intact cells, but the responses to parathyroid hormone, isoproterenol, prostaglandin E2, salmon calcitonin and...

We describe a new, rapid, and simple column-chromatographic procedure for 25-OH vitamin D3 in plasma. The vitamin is extracted by use of Sep-pak C18 (octadecyl alkylated silicic acid), a short factory-packed reversed-phase column, and 25-OH vitamin D2 + 25-OH vitamin D3 fraction is eluted with methanol/water. The 25-OH D2 and 25-OH D3 are then well resolved on a high-resolution 3-micrometer sil...