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PubMed1981

Simplified assay of vitamin D2 in fortified dried milk by using two steps of high-performance liquid chromatography.

A simplified method for the determination of vitamin D2 in fortified dried milk was established by using two steps of high-performance liquid chromatography (HPLC). About 1 g of fortified dried milk was accurately weighed and directly saponified. The extracted unsaponifiable matter was first subjected to preparative HPLC using a Nucleosil 5C18 column (reversed-phase type) with acetonitrile-methanol (1:1) as a mobile phase and a fraction containing vitamin D2 was separated. The separated fraction was subsequently subjected to analytical HPLC using a Zorbax SIL column (straight-phase type) with 0.4% isopropanol in n-hexane as a mobile phase. Since the peak corresponding to vitamin D2 was clearly observed with separation from other concomitants on the chromatogram of the analytical HPLC, the vitamin was assayed by estimating the peak height. The overall recovery of vitamin D2 by the proposed method was 94.3 +/- 2.3% (mean +/- SD). Naturally occurring vitamin D3 derived from cow's milk was negligible in commercial fortified dried milk sold in Japan. When the proposed method was applied to 5 kinds of commercial fortified dried milk, satisfactory results were obtained.

Animals↗
PubMed1987

Interactions between 1,25-dihydroxyvitamin D3 and vitamin D2: effects of pharmacologic doses in normal individuals.

To determine whether the administration of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) affects the conversion of a pharmacologic dose of vitamin D2 to 25-hydroxyvitamin D (25OHD), 20 normal subjects received two separate doses of vitamin D2--one with and the other without the concomitant administration of 1,25(OH)2D3. Serum 1,25(OH)2D rose in response to 1,25(OH)2D3 administration and fell when vitamin D2 was given alone. Serum osteocalcin rose in response to 1,25(OH)2D3 administration. Serum 25OHD rose in response to vitamin D2 administration regardless of whether the subjects also received 1,25(OH)2D3. The data from this study in humans support the suggestion that the effects of 1,25(OH)2D3 on serum 25OHD concentrations are mediated through mechanisms other than impairment of production.

25-Hydroxyvitamin D 2↗
PubMed1998

Unique 24-hydroxylated metabolites represent a significant pathway of metabolism of vitamin D2 in humans: 24-hydroxyvitamin D2 and 1,24-dihydroxyvitamin D2 detectable in human serum.

We have produced evidence for a new metabolic pathway for vitamin D2 in humans involving the production of 24-hydroxyvitamin D2 (24OHD2) and 1,24-dihydroxyvitamin D2 [1,24-(OH)2D2]. These metabolites were produced after either a single large dose (10(6) IU) of vitamin D2 or repeated daily doses between 10(3) and 5 x 10(4) IU. We developed assay systems for the metabolites in human serum and showed that in some chronically treated patients, the concentration of 1,24-(OH)2D2 equalled that of 1,25-(OH)2D2 at about 100 pmol/L. The metabolites were identified by high performance liquid chromatography with diode array spectrophotometry for 24OHD2 and by high resolution gas chromatography-mass spectrometry for 1,24-(OH)2D2. We show that 1,24-(OH)2D2 synthesis can be stimulated by PTH, indicating a renal origin for this metabolite and postulate that it is formed from 24OHD2, which may be synthesized in liver. We conclude from this study that vitamin D2 gives rise to two biologically active products, 1,24-(OH)2D2 and 1,25-(OH)2D2, and that 1,24-(OH)2D2 could be an attractive naturally occurring analog of 1,25-(OH)2D3 for clinical use.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Serum dihydroxyvitamin D metabolite concentrations in patients on chronic anticonvulsant drug therapy: response to pharmacologic doses of vitamin D2.

We examined the effects of chronic anticonvulsant drug administration on the serum concentrations of dihydroxyvitamin D metabolites and the response of these metabolite levels to short-term treatment with pharmacologic doses of vitamin D2. Twelve patients maintained on chronic combined diphenylhydantoin and phenobarbital therapy were studied before and after the administration of vitamin D2, 75,000 units/week for 6 weeks. Prior to vitamin D2 administration, the patient group demonstrated decreased serum calcium (P less than 0.01) and increased serum iPTH (P less than 0.02) concentrations relative to 18 matched controls. Serum 25OHD and 24,25(OH)2D concentrations in the patient group were reduced by 38% and 75% (P less than 0.001), while serum 1,25(OH)2D concentration was increased by 27% (P less than 0.05) relative to control values. After vitamin D administration serum calcium and iPTH concentrations in the patient group were restored to values that were not significantly different from control levels. Serum 25OHD and 24,25(OH)2D concentrations were increased by 4.6- and 6.3-fold, respectively, to supranormal levels. Serum 1,25(OH)2D concentration exhibited an unexpected further 30% increase over pretreatment values, resulting in a return of the serum 1,25(OH)2D/24,25(OH)2D concentration ratio to a normal value. These data indicate that in patients treated chronically with anticonvulsant drugs, serum 25OHD concentration responds appropriately to vitamin D2 administration, but regulation of renal dihydroxy metabolite formation may be altered.

25-Hydroxyvitamin D 2↗
PubMed2000

New model of atherosclerosis in insulin resistant sand rats: hypercholesterolemia combined with D2 vitamin.

To overcome the sand rats' resistance to cholesterol induced atherosclerosis, animals were given D2 vitamin at 2000 IU/rat per day associated with cholesterol-enriched diet for 45 days, following 45 days of high cholesterol diet alone. At days 0, 45 and 90, plasma parameters, aortic and heart morphology were examined. Other animals receiving a high cholesterol diet alone were used as a control group. Results showed at day 45 severe hypercholesterolemia, elevated plasma LDL and VLDL-cholesterol, oxidized LDL and calcium levels, a rise of lecithin cholesterol acyl transferase activity and moderate hyperinsulinemia. Lesions were characterized by widening of the first interlamellar spaces in the aorta, fibrosis of coronary arterial wall and recent foci of myocardial fibrosis. At day 90, plasma calcium level decreased and oxidized LDL were more enhanced. Insulin resistance development was associated with glucose intolerance and hyperinsulinemia. The D2 vitamin administration induced advanced atherosclerotic lesions in arterial wall, represented by the rupture of elastic lamellae, smooth muscle cell proliferation and lipid-calcic core. The complicated plaque frequently evolved into ulcerations. The ischaemic effects were represented by acute myocardial infarction. D2 vitamin is an atherogenic agent which, when associated with hypercholesterolemia, allows the development of advanced atherosclerotic lesions in sand rat which resembles human plaque.

Animals↗
PubMed1985

Absorption, dosage, and effect on mineral homeostasis of 25-hydroxycholecalciferol in premature infants: comparison with 400 and 800 IU vitamin D2 supplementation.

Because the efficiency of vitamin D absorption or hepatic uptake and 25-hydroxylation appears decreased in very premature infants, the routine use of 25-hydroxycholecalciferol (25-OHD3) supplementation has been suggested. Absorption studies of a 3 micrograms/kg orally administered dose of 25-OHD3 showed peak serum 25-hydroxyvitamin D2 and -vitamin D3 (25-OHD) concentrations at 4 to 8 hours similar in timing but of lesser magnitude to those seen in adults. Administration of 1 microgram/kg birth weight/day of 25-OHD3 corrected moderately low, but not very low serum (25-OHD) concentrations, and 2 micrograms/kg BW/day resulted in rapid and sustained increase in serum 25-OHD. Administration of 800 IU ergocalciferol (D2) also produced significantly higher serum 25-OHD concentrations than those in infants given 400 IU vitamin D2, but increases in serum 25-OHD were more gradual than in infants given 25-OHD3. In treatment trials with infants weighing less than 1500 gm, those given 800 IU D2, compared with those given 400 IU D2, had higher serum calcium concentrations and less frequent moderate or severe hypomineralization. Infants given 2 micrograms/kg BW 25-OHD3 had a significant increase in serum phosphorus values, but a decrease in serum calcium and magnesium concentrations, and parathyroid hormone also was suppressed to low normal values. The frequency of moderate to severe hypomineralization remained the same as in infants given 400 IU D2. In a subgroup of infants, serum 1,25-dihydroxyvitamin D was elevated over adult values, both in infants given 25-OHD3 (68.5 +/- 8.4 pg/ml) and in infants given vitamin D2 (60 +/- 6.7 pg/ml). Serum vitamin D concentrations were undetectable in four of six infants receiving 25-OHD3, but were elevated (5 to 31 ng/ml) in four infants receiving vitamin D2. Although 800 to 1000 IU D2 can be recommended as routine vitamin D supplementation in very premature infants fed standard formula, the use of 25-OHD3 requires further study.

Absorption↗
PubMed1982

Effect of vitamin D2 on the assay of 24,25-dihydroxyvitamin D3 in man.

Serum levels of the dihydroxylated metabolite of vitamin D3, 24,25-dihydroxycholecalciferol (24, 25(OH)2D3) were measured by competitive protein-binding assay in 2 anephric patients while undergoing therapy with 25-hydroxycholecalciferol (25(OH)D3) and, at a later date, vitamin D2, ergocalciferol. Whereas there was no increase in serum levels of 24, 25 (OH)2D3 when the patients were treated with 25 (OH)D3, a significant increase was apparently seen when vitamin D2 was given. These results suggest that a metabolite of vitamin D2, non-renal in origin, may be interfering in the assay for 24, 25 (OH)2D3. The different levels of serum 24, 25 (OH)2D3 in anephric man found by various groups of workers are explained by these results.

24,25-Dihydroxyvitamin D 3↗
PubMed1989

Differences in mineral metabolism among nonhuman primates receiving diets with only vitamin D3 or only vitamin D2.

We tested for differences in aspects of mineral metabolism during the administration of diets with only vitamin D3 or only vitamin D2 in four nonhuman anthropoid primate species [two catarrhini, Macaca fascicularis (crab-eating macaque) and Macaca mulatta (rhesus macaque), and two platyrrhini, Saimiri sciureus (squirrel monkey) and Aotus vociferans (night monkey)]. All four species maintained approximately 2- to 3-fold higher serum 25-hydroxyvitamin D (25OHD) level while receiving vitamin D3 than while receiving similar amounts of vitamin D2. Serum 25OHD in M. mulatta receiving the standard primate dietary supplement of vitamin D3 was high enough (360 +/- 60 vs. 70 +/- 25 nM in vitamin D-supplemented humans; P less than 0.0001) to suggest that this widely used level of vitamin D3 supplementation is excessive for some M. mulatta. Serum 24,25-dihydroxyvitamin D [24,25-(OH)2D] in A. vociferans was uniquely high [P less than 0.01; species mean, 19 +/- 5, 95 +/- 12, and 27 +/- 5 nM in groups receiving diets with 1.5 IU vitamin D3/g, 6.6 IU vitamin D3/g, and 15 IU vitamin D2/g, respectively; mean 24,25-(OH)2D from the other three species pooled across three diets was 7 +/- 5 nM]. We confirmed relative resistance to 1,25-(OH)2D in S. sciureus, manifested by osteomalacia and moderately high serum 1,25-(OH)2D. Serum 1,25-(OH)2D in S. sciureus increased 4-fold (P less than 0.05) when the precursor in serum was changed from 250HD3 to 250HD2, suggesting that this species shows more severe resistance to 1,25-(OH)2D2 than to 1,25-(OH)2D3. In conclusion, we found many differences in vitamin D metabolism among four nonhuman anthropoid primate species. The striking feature in A. vociferans (high, 24,25-(OH)2D without high 25OHD in serum independent of whether diet contained only vitamin D3 or only vitamin D2) should allow determination of whether 24,25-(OH)2D functions as a unique agonist or an inactive metabolite in this species.

Animals↗
PubMedDate not supplied

Metabolic bone disease in alcoholic cirrhosis: a comparison of the effect of vitamin D2, 25-hydroxyvitamin D, or supportive treatment.

In a study of 56 alcoholics with liver cirrhosis, 18 (32%) had decreased bone density and low levels of serum 25-hydroxyvitamin D (25-OH-D) (less than 20 ng per ml). To compare the efficacy of vitamin D2 and 25-OH-D treatment in correcting the metabolic bone disease in alcoholic cirrhosis, the 18 patients were randomized in the following manner, in groups of six patients each: Group 1, control (received no supplemental vitamin D treatment); Group 2, given vitamin D2 (50,000 IU p.o.) two to three times weekly, and Group 3, treated with 25-OH-D (20 to 50 mg p.o.) daily as required to attain normal serum 25-OH-D levels. The study period lasted 6 to 12 months (mean, 10.7 months). Initial histomorphometric study of transiliac bone biopsy with double tetracycline labeling in nine patients in whom biopsy was feasible showed only osteoporosis without evidence of osteomalacia. By the end of the study, serum 25-OH-D levels in the control group (Group 1) raised slightly while showing marked improvement in Groups 2 and 3. Bone density results remained unchanged in control patients but demonstrated a significant increase in both treatment groups. Vitamin D2 and 25-OH-D were equally effective in increasing bone density measurements. Posttreatment biopsies were performed in three patients of Group 2 and two patients of Group 3. While the histomorphometric results in Group 3 were not conclusive, in Group 2 improvement in static measures of bone remodeling was noted. Osteoporosis is the usual form of bone disease in alcoholic cirrhosis and a response to either vitamin D2 or 25-OH-D treatment is suggested.

25-Hydroxyvitamin D 2↗
PubMed1985

Different actions of vitamin D2 and D3 on bone metabolism in patients treated with phenobarbitone/phenytoin.

In 22 epileptic outpatients treated for at least 1 year with phenobarbitone/phenytoin the local and total bone mass, together with serum and urinary indices of calcium metabolism, were measured before and during treatment with either vitamin D2 or D3, 4,000 IU daily for 24 weeks. The results showed a distinct difference in the action of the two vitamins on bone metabolism during anti-convulsant treatment. The bone mass increased during treatment with vitamin D2, whereas the vitamin D3-treated patients showed unchanged values of bone mass, but an increased excretion rate of calcium, probably caused by increased intestinal calcium absorption. The data demonstrate that vitamins D2 and D3 (or their metabolites) have quantitative different effects in patients treated with phenobarbitone/phenytoin.

Adult↗
PubMed1981

Autoradiographic studies with 3H 1,25 (OH)2 vitamin D2 and 3H 25 (OH) vitamin D3 in rat parathyroid glands.

After injection of radiolabeled 1,35 (OH)s vitamin D3, nuclear concentration of radioactivity is observed in parenchymal cells o hte parathyroid gland in pregnant, adult male, and 10-day male neonatal rats. In competition studies with unlabeled 1,25 (OH)2 vitamin D3, but not with 25 (OH) vitamin D3, in contrast to 3H 1,25 (OH)2 vitamin D3, do not show nuclear concentration in cells of te parathyroid. The results of te autoradiographic studies suggest the presence of receptors for a direct effect of 1,35 (OH)2 vitamin D3 on the parathyroid gland for modulation of parathyroid hormone secretion.

Aging↗
PubMed1975

Actions of vitamins D2 and D3 and 25-OHD3 in anticonvulsant osteomalacia.

In 54 epileptic outpatients treated for at least one year with anticonvulsants the bone mineral content (B.M.C.), an estimate of total body calcium, and serum calcium were measured before and during treatment with three doses of cholecalciferol (vitamin D3; 200, 100, and 50 mu-g daily) and 25-hydroxycholecalciferol (25-OHD3; 40, 20, and 10 mu-g daily) for 12 weeks. The results, when compared with the effects of calciferol (vitamin D2; 200, 100, and 50 mu-g daily) in 40 epileptic outpatients, showed different actions in anticonvulsant osteomalacia of vitamin D2 on the one hand and vitamin D3 and 25-OHD3 on the other. In the patients who received vitamin D2 an increase in B.M.C. was found whereas serum calcium was unchanged. The patients who received vitamin D3 or 25-OHD3 showed an increase in serum calcium but unchanged values of B.M.C. The results suggest that liver enzyme induction cannot alone explain anticonvulsant osteomalacia.

Anticonvulsants↗
PubMed1974

1alpha-Hydroxyvitamin D2: a potent synthetic analog of vitamin D2.

A hydroxy analog of vitamin D(2), 1alpha-hydroxyvitamin D(2), has been synthesized and tested for biological activity. This vitamin derivative is active in stimulating intestinal calcium transport and bone calcium mobilization in the rat and exhibits antirachitic activity. Its biopotency is comparable to that of the corresponding vitamin D(3) analog, 1alpha-hydroxyvitamin D(3).

Animals↗
PubMed1978

[The action of vitamin D2 and of 25-hydroxy-cholecalciferol on calcemia and urinary calcium excretion in the alcoholic cirrhotic (author's transl)].

In 2 similar groups of alcoholic cirrhotics with definite hepatic failure, the results of the oral administration of 25-hydroxycholecalciferol and of vitamin d2 on calcemia and urinary calcium excretion were studied. 25-hydroxycholecalciferol definitely increases calcemia and urinary calcium excretion, this action being superior to that of vitamin D2. This action which occurs, at least in part, by an increase in intestinal calcium absorption, deomonstrated the true nature of the "hepatic block" of vitamin D2 in alcoholic cirrhosis and the value of the administration of 25-hydroxycholecalciferol.

Calcium↗
PubMed1986

[Comparative studies of calcium resorption modified by vitamin D2 and D3 in patients with chronic renal failure and dialysis patients].

In 16 patients with a chronic renal insufficiency at the stage of the compensated retention and 13 test persons of the chronic haemodialysis programme determinations of the total calcium and of the ionized calcium fraction as well as investigation of the intestinal calcium absorption by means of the isotope 47Ca were performed. In these cases the influence of vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) on these parameters of the calcium metabolism was compared. Under the treatment with vitamin D a normalization of the serum calcium levels concerning the total calcium concentration as well as with regard to the ionized calcium fraction was achieved; this effect took place parallel to the improvement of the intestinal calcium absorption. Vitamin D3, had a more favourable effect than vitamin D2. The necessary doses are below 40,000 U a day.

Blood Urea Nitrogen↗
PubMedDate not supplied

[The effects of vitamin D2 on the lipid profile and on the platelet and cardiovascular activities in castrated or testosterone-treated male rats].

The changes in serum and hepatic lipid fractions (LT, Col, TG, beta-LP), aggregability indices (IAg), platelet adhesiveness (IA), atherogenicity (Ia) and microscopic aspect of aorta and myocardium in three groups of animals injected with vitamin D2: normal, orchiectomized and treated with testosterone, were followed up. In the normal animals the injection of vitamin D2 induced the increase of all lipid fractions, of IA, IAg, Ia and histologically microcalcifications at the coronaries level were present; in the orchiectomized animals the biochemical changes were less marked and histologically thickenings of aortic and coronary endothelium with areas of intestinal sclerosis in the myocardium were found. In the animals with hyperandrogenism, the administration of vitamin D2 induced the decrease of TG and increase of IAg and IA; histologically, aspects similar to those noticed after the administration of testosterone alone were present. It is concluded that hypervitaminosis D induces a marked increase of serum lipid fractions in the normal animals, while the histological examination revealed more marked changes in conditions of sexual function cessation.

Animals↗