cholecalciferol and 25-26-dihydroxycholecalciferol

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Biological Transport; Bone and Bones; Bone Resorption; Calcifediol; Calcitonin; Calcitriol; Calcium; Calcium-Binding Proteins; Cartilage; Chemical Phenomena; Chemistry; Cholecalciferol; Dihydroxycholecalciferols; Female; Humans; Hydroxycholecalciferols; Intestinal Absorption; Intestines; Kidney; Liver; Minerals; Parathyroid Hormone; Phosphorus; Pregnancy; Skin; Steroid Hydroxylases; Ultraviolet Rays; Vitamin D; Vitamin D-Binding Protein

Vitamin D metabolism was studied in the 'Hannover Pig', a strain which suffers from pseudo vitamin D-deficiency rickets, type I. Animals of this strain are known to be devoid of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase and -24-hydroxylase activities. Pigs with florid rickets and hypocalcaemia were treated with single im injections of 0.25 to 1.25 mg of vitamin D3, doses that have been shown in previous studies to be effective in producing transient healing of rachitic symptoms. The levels of vitamin D3 and its most relevant physiological metabolites in plasma were estimated at intervals before and after this vitamin D3 treatment. Vitamin D3 rose from 14.8 +/- 8.1 to 364 +/- 190 nmol/l (mean +/- SD) 2 to 3 days post injectionem, 25-hydroxyvitamin D3 from 131.0 +/- 46.2 to 1068 +/- 160 nmol/l within 7 days post injectionem. The 1 alpha, 25-dihydroxyvitamin D3 concentration in plasma was elevated from 73.9 +/- 25.0 to 281 +/- 168 pmol/l 2 to 3 days post injectionem and declined continually from that time. 24R,25-dihydroxyvitamin D3 and 25S,26-dihydroxyvitamin D3 levels after treatment showed different responses in different animals being either elevated or unchanged. Clinical healing of the pigs with these doses of vitamin D3 was attributed to the transient rise of 1 alpha,25-dihydroxyvitamin D3 in plasma. It was assumed that 1 alpha,25-dihydroxyvitamin D3 synthesis takes place under these circumstances in extrarenal tissues.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Calcium; Cholecalciferol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Radioimmunoassay; Rickets; Swine

By use of a single-cartridge system, 1,25-dihydroxyvitamin D [1,25(OH)2D] is extracted and purified from a plasma or serum sample. Proteins are removed and 1,25(OH)2D is liberated from the sample with acetonitrile. The acetonitrile extract is applied to the nonpolar octadecylsilanol silica cartridge, in which 1,25(OH)2D is retained while polar compounds are eluted. Then by "phase-switching" on the same cartridge, 1,25(OH)2D is sufficiently resolved from other vitamin D metabolites and extraneous lipophilic compounds to allow its quantification by radioreceptor assay according to an established procedure. Mean (and SD) values for 1,25(OH)2D in serum of 29 normal, 27 chronic renal failure, and nine pregnant subjects were 28.2 (11.3), 10.9 (5.2), and 47.3 (12.9) ng/L, respectively. Results compared well with those of an established radioreceptor procedure. This procedure offers the advantage of a single rapid purification step not involving "high-performance" liquid chromatography or evaporation, under nitrogen, of polar solvents such as acetonitrile or methanol.

Topics: 24,25-Dihydroxyvitamin D 3; Calcitriol; Cholecalciferol; Dihydroxycholecalciferols; Female; Humans; Kidney Diseases; Labor, Obstetric; Pregnancy; Radioligand Assay; Specimen Handling

Serum concentrations of vitamin D metabolites were measured before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks, in 22 epileptic outpatients receiving phenobarbitone/phenytoin. The serum concentration of total 1,25(OH)2D did not change during the treatment period in any of the treatment groups. On the other hand, in the vitamin D2 group, serum 25(OH)D2, total 25(OH)D, and 24,25(OH)2D increased significantly during the trial, whereas serum concentrations of the vitamin D3 metabolites were unchanged. In the vitamin D3 group, serum concentrations of the vitamin D3 metabolites increased significantly, whereas the vitamin D3 metabolite levels remained unchanged. However, vitamin D3 treatment resulted in a 2-4-fold greater increase in serum concentrations compared to vitamin D2 treatment. Treatment with vitamin D2 and vitamin D3 in the same dose in IU results in considerably different serum concentrations of the vitamin D metabolites.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Adult; Aged; Calcifediol; Calcium; Cholecalciferol; Dihydroxycholecalciferols; Epilepsy; Ergocalciferols; Female; Humans; Male; Middle Aged; Phenobarbital; Phenytoin

To determine the effect of supplemental dietary vitamin D3 on concentration of vitamin D and its metabolites in milk, 20 Holstein cows were assigned to four groups and fed either 0, 10,000, 50,000, or 250,000 IU of vitamin D3/d beginning approximately 2 wk prepartum and continuing through wk 12 of lactation. Samples of blood plasma and milk were assayed for concentrations of vitamin D, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D. Only the daily dosage of 250,000 IU caused significant increases of concentrations of vitamin D or 25-hydroxyvitamin D in plasma. Concentrations of vitamin D and 25-hydroxyvitamin D in milk were approximately equal and averaged .2 ng/ml. Little 1,25-dihydroxyvitamin D and no 24,25-dihydroxyvitamin D could be detected in milk from any of the four treatment groups. Cows fed 250,000 IU of vitamin D3/d produced milk containing 54 IU of vitamin D activity per liter, whereas unsupplemented cows produced milk containing 17 IU/L. Oral supplementation with up to 250,000 IU of vitamin D3/d does not increase effectively vitamin D activity of milk.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Cattle; Cholecalciferol; Dihydroxycholecalciferols; Female; Food, Fortified; Milk; Pregnancy; Vitamin D

Serum concentrations of the main vitamin D metabolites and of calcium, phosphate, and alkaline phosphatase were determined in each of the three trimesters of pregnancy and in simultaneously obtained maternal and cord blood at delivery in 22 epileptic women treated with diphenylhydantoin or carbamazepine alone or with a combination with one other drug. The results were compared with similarly obtained data from 22 normal pregnancies. Women in both groups received supplements of 400 IU vitamin D3 per day. All the women had 25-hydroxyvitamin D levels within the normal range for healthy adults (greater than 12 ng/ml) throughout pregnancy. The epileptic women had, however, significantly (p less than 0.05) lower median 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels and higher median 25,26-dihydroxyvitamin D values than the reference group. The 24,25-dihydroxyvitamin D concentrations did not differ significantly, but the median ratio of 24,25-dihydroxyvitamin D to 25-hydroxyvitamin D was higher in the epileptic women at the end of pregnancy (p = 0.05). The respective differences in cord serum concentrations reflected those of the mothers at delivery. Serum calcium tended to be lower during epileptic pregnancy, but none were hypocalcemic. The alkaline phosphatase and phosphate values did not consistently differ from those of the reference women. The median alkaline phosphatase level of cord serum was slightly higher in the epileptic group, but the calcium and phosphate levels were similar to the reference values. The various biochemical parameters of the carbamazepine-treated women tended to be intermediate between those of the healthy and diphenylhydantoin-treated groups. Antiepileptic drug therapy appears to affect vitamin D metabolism and calcium homeostasis during pregnancy. The derangements may not be of major clinical significance, however, in vitamin D-supplemented and normally functioning women on long-term low-dose therapy.

Topics: 24,25-Dihydroxyvitamin D 3; Adolescent; Adult; Alkaline Phosphatase; Anticonvulsants; Calcifediol; Calcitriol; Calcium; Carbamazepine; Cholecalciferol; Dihydroxycholecalciferols; Epilepsy; Female; Fetal Blood; Homeostasis; Humans; Phenytoin; Phosphates; Pregnancy; Pregnancy Complications; Vitamin D

The metabolism of vitamin D3 was studied in bilaterally nephrectomized pigs and cotnrol pigs maintained for 8-10 days by daily peritoneal dialysis. Two or three pharmacological doses of vitamin D3 were given im, one on day 0 and the others on days, 4, 6, or 7 of the 8- to 10-day experimental periods. Nephrectomized pigs had extremely high plasma concentrations of 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] and 25,26-(OH)2D3 at the end of the 8- to 10-day periods; similar levels were present in control pigs. However, nephrectomized pigs had no detectable increase in plasma 25-hydroxyvitamin D3 (25OHD3)-26,23-lactone concentrations throughout the experiment, in contrast with the high plasma concentrations of 25OHD3-26,23-lactone in the control pigs. Much higher plasma 25OHD3 concentrations were present in the nephrectomized pigs than in the control pigs. Plasma 1,25-(OH)2D concentrations in nephrectomized and control pigs were similar during most of the experiment, except the anephric pigs usually had significantly higher plasma 1,25-(OH)2D concentrations for several days after the vitamin D3 injections. These studies demonstrate extrarenal production of 24,25-(OH)2D3, 25,26-(OH)2D3, and possibly 1,25-(OH)2D, and kidney-dependent synthesis of 25OHD3-26,23-lactone in the pigs.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcitriol; Calcium; Cholecalciferol; Dihydroxycholecalciferols; Female; Male; Nephrectomy; Swine

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcitriol; Calcium; Cholecalciferol; Culture Media; Dihydroxycholecalciferols; Ethanol; In Vitro Techniques; Male; Parathyroid Glands; Parathyroid Hormone; Rats; Rats, Inbred Strains

Here we report the use of newly developed and established techniques for the determination of plasma levels of a broad spectrum of vitamin D3 metabolites, including vitamin D3 and 25OHD3-lactone, in normal humans, chronic renal failure patients, and anephric subjects. The methodology described consisted of methanol-methylene chloride extraction, Lipidex-5000 chromatography with stepwise gradient elution, normal-phase HPLC with concave gradient elution, and sensitive ligand-binding assays. The results of the study strongly suggest an extrarenal source(s) for 24,25(OH)2D3 and 25,26(OH)2D3 and indicate that both 25OHD3-lactone and 1,25(OH)2D3 may be produced solely in the kidney of the human. Significant reductions or nondetectable plasma levels of vitamin D3 in the renal disease patients may reflect abnormalities in the hepatobiliary-intestinal and/or cutaneous metabolism of vitamin D.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Cholecalciferol; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Kidney Failure, Chronic; Methods; Nephrectomy

Topics: Animals; Biotransformation; Calcifediol; Cholecalciferol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Ergocalciferols; Hydroxycholecalciferols; Male; Mass Spectrometry; Radioisotope Dilution Technique; Rats; Tritium