Interrelationships in rats of tissue pools of cholecalciferol and 25-hydroxycholecalciferol formed in u.v. light

Lawson, David; Sedrani, Saleh H.; Douglas, Jeffrey A.

doi:10.1042/bj2330535

Cited by 24 publications

(22 citation statements)

References 21 publications

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“…Since the vitamin D3 was removed from these plasmas by actin affinity chromatography, the cutaneously produced vitamin D3 was bound to DBP as previously assumed (10)(11)(12). Our data conform to the recognized, gradual egress ofcutaneously synthesized vitamin D3 (2,6,21,22), and underscore the differences between the cutaneous and dietary sources of the vitamin (2).…”

Section: Discussionsupporting

confidence: 55%

Human plasma transport of vitamin D after its endogenous synthesis.

Haddad

Matsuoka²,

Hollis³

et al. 1993

J. Clin. Invest.

235

153

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IntroductionTransport of vitamin D3 from its sites of cutaneous synthesis into the circulation has been assumed to be via the plasma vitamin D binding protein (DBP). We studied vitamin D transport from the skin in seven healthy volunteers who received whole body irradiation with 27 mJ /cm2 dosage of ultraviolet B light (290-320 nm). Samples of venous blood were collected serially in EDTA and immediately chilled. In KBr, plasma samples were ultracentrifuged to provide a rapid separation of proteins of density < and > 1.3 g/ml. Upper and lower phases and serial fractions were analyzed for vitamin D3 (extraction, HPLC), cholesterol (enzyme assay), and human DBP (hDBP) (radial immunodiffusion). Total plasma vitamin D (basal level < 1 ng/ml) increased by 10 h and peaked at 24 h (9 ± 1 ng/ml). 98% of the D3 remained at the density > 1.3 layers for up to 7 d, whereas cholesterol (> 85%) was detected at density < 1.3 and all of the hDBP was at density > 1. Vitamin D is a precursor ofa renal steroid hormone, 1 ,25-dihydroxyvitamin D (1). This precursor, however, cannot be provided by enzymatic synthesis. Its supply depends on ultraviolet (UV) irradiation ofthe skin or absorption from the diet. Since few natural foodstuffs contain much vitamin D (2), observers consider the endogenous, cutaneous production of cholecalciferol to be the physiological mechanism of precursor supply (2-5).Distinct differences are recognized for the cutaneous synthesis vs. diet-derived supply of vitamin D (2, 6). A more efficient and sustained supply of vitamin D is associated with UV irradiation of the skin or parenteral administration of vitamin D (2, 6). In contrast, oral vitamin D consumption leads to rapid but less sustained availability of sterol and a similar pattern of increase in the hepatic metabolite, 25-hydroxycholecalciferol (2, 6-9).Many studies have addressed the mode of vitamin D transport after oral consumption (6), but no direct studies of the plasma transport of cutaneously-derived vitamin D are reported. It has been assumed that vitamin D synthesized in skin enters the blood stream on the plasma binding protein for vitamin D and its metabolites (DBP)' and this assumption is based on in vitro studies ofthe relative potency of vitamin D in binding to DBP as compared with 7-dehydroxycholesterol, lumisterol, tachysterols3 and pre-D3 (10-12). However, other plasma carriers are recognized and some facilitate hepatic ( 13-15) and hepatocyte (16) Cutaneous irradiation. Seven subjects were exposed to 27 mJ/cm2 of . Venous blood samples were taken at baseline, 10,24, 72, and 168 h after the UV-B exposure, immediately 1. Abbreviation used in this paper: DBP, vitamin D binding protein.

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Section: Discussionsupporting

confidence: 55%

Human plasma transport of vitamin D after its endogenous synthesis.

Haddad

Matsuoka²,

Hollis³

et al. 1993

J. Clin. Invest.

235

153

View full text Add to dashboard Cite

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“…It has been proposed that the low vitamin D status might be due to increased vitamin clearance from serum and enhanced storage of vitamin D by adipose tissue [37,38], as demonstrated in models of vitamin D deficient nonobese rats after vitamin D repletion [3,[39][40][41], with vitamin replete rats [42] and at autopsy in humans [43]. In nonobese rats, vitamin D stored in adipose tissue was released during periods of fasting with 15% weight loss, but at a rate far below the release of triglyceride [40].…”

Section: Discussionmentioning

confidence: 98%

Vitamin D and the Bariatric Surgical Patient: A Review

2008

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“…Several pharmacokinetic studies performed in the last four decades have demonstrated its hydrophilic properties, leading to higher solubility in organic solvents, lower trapping in the adipose tissues, smaller distribution volume, and shorter half-life (10-13 days), when compared to the parental compound cholecalciferol (30-45 days) [13,26,28]. The good predictability of achieved 25(OH)D levels in the short term, along with the effective PTH suppression and manageability in case of intoxication, may confirm the advantages of calcidiol supplementation versus cholecalciferol [14,16].…”

Section: Introductionmentioning

confidence: 99%

Correction of vitamin D status by calcidiol: pharmacokinetic profile, safety, and biochemical effects on bone and mineral metabolism of daily and weekly dosage regimens

et al. 2017

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Summary Rationale: Calcidiol can be employed to correct vitamin D deficiency. Main results: Calcidiol administered at daily and weekly regimens over a period of 3 months was able to successfully raise 25-hydroxyvitamin D levels without altering other markers related to bone and mineral metabolism. Significance: Calcidiol supplementation is effective and safe. Introduction The correction of vitamin D status is necessary to maintain an optimal mineral and skeletal homeostasis. Despite cholecalciferol (vitamin D 3 ) is the most commonly used drug for vitamin D supplementation, the more hydrophilic compound calcidiol (25-hydroxyvitamin D 3 ) can be employed at daily, weekly, and monthly regimens to reach in the short term the target levels of serum 25-hydroxyvitamin D [25(OH)D]. In the administration of different doses of calcidiol pharmacokinetic study (ADDI-D study), the efficacy and safety of daily and weekly dosages of calcidiol were tested. Methods A total of 87 Caucasian, community-dwelling, postmenopausal women, aged 55 years or older, with vitamin D inadequacy (serum 25(OH)D levels <30 ng/ml, with mean 25(OH)D below 20 ng/ml, namely 16.5 ± 7.5 ng/ml) were randomized to receive three different dosages of calcidiol: 20 μg/day, 40 μg/day, and 125 μg/week for 3 months. The attained level of serum 25(OH)D was selected as primary endpoint to assess efficacy, while other parameters of mineral metabolism, (serum calcium, parathyroid hormone, phosphate, FGF23, urinary calcium, and markers of bone turnover) were assessed as secondary endpoints to establish safety. Results In all the three groups, serum 25(OH)D values significantly and promptly rose and plateaued above the 30 ng/ml threshold remaining within safety interval after 14 days of treatment, with similar efficacy for the similar daily and weekly dose regimens. The different dosages were also equally effective in controlling secondary hyperparathyroidism. No significant changes in calcium and phosphate metabolism and in bone turnover markers were observed for any of the treatments, confirming the safety of this compound. Conclusions The results of this study demonstrate the shortand mid-term efficacy and safety on core parameters of mineral metabolism of different daily or weekly dosages of calcidiol when used to treat vitamin D inadequacy or deficiency in postmenopausal women. Further studies are needed to assess falls as primary outcome of calcidiol supplementation.

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Interrelationships in rats of tissue pools of cholecalciferol and 25-hydroxycholecalciferol formed in u.v. light

Cited by 24 publications

References 21 publications

Human plasma transport of vitamin D after its endogenous synthesis.

Human plasma transport of vitamin D after its endogenous synthesis.

Vitamin D and the Bariatric Surgical Patient: A Review

Correction of vitamin D status by calcidiol: pharmacokinetic profile, safety, and biochemical effects on bone and mineral metabolism of daily and weekly dosage regimens

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