Alpha-hydroxyvitamin D3 Research Articles

Retraction of: Amelioration of Hemiplegia-Associated Osteopenia More Than 4 Years After Stroke by 1 Alpha-Hydroxyvitamin D3 and Calcium Supplementation

HomeStrokeVol. 50, No. 5Retraction of: Amelioration of Hemiplegia-Associated Osteopenia More Than 4 Years After Stroke by 1 Alpha-Hydroxyvitamin D3 and Calcium Supplementation Free AccessRetractionPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessRetractionPDF/EPUBRetraction of: Amelioration of Hemiplegia-Associated Osteopenia More Than 4 Years After Stroke by 1 Alpha-Hydroxyvitamin D3 and Calcium Supplementation Originally published22 Apr 2019https://doi.org/10.1161/STR.0000000000000187Stroke. 2019;50:e145This article is retracted byAmelioration of Hemiplegia-Associated Osteopenia More Than 4 Years After Stroke by 1α-Hydroxyvitamin D3 and Calcium SupplementationThe Editors of Stroke are retracting the following article: Amelioration of Hemiplegia-Associated Osteopenia More Than 4 Years After Stroke by 1 Alpha-Hydroxyvitamin D3 and Calcium Supplementation. Stroke. 1997; 28:736–739. DOI: 10.1161/01.STR.28.4.736The above article was part of an analysis done by Bolland et al1 that detected serious problems with the integrity of the data and was identified by Dr. Robert A. Gross, Editor of Neurology, as fraudulent.2 The lead author, Dr. Sato (now deceased), his coauthors, and institution did not respond to a request for information; therefore, the editors have determined that the best course of action is to issue a notice of retraction.[original article URL: https://www.ahajournals.org/doi/10.1161/01.STR.28.4.736]

Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men.

Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men.

Crises épileptiques révélant des anomalies du métabolisme phosphocalcique

Hypocalcemia due to hypoparathyroidism produces a broad spectrum of clinical manifestations, but overt symptoms may be sparse. One unusual presentation is onset or aggravation of epilepsy in adolescence revealing hypoparathyroidism. This situation can lead to delayed diagnosis, with inefficacity of the antiepileptic drugs. We report five cases of adolescence-onset epilepsy with unsuccessful antiepileptic therapy, even with gradually increasing dose. Physical examination revealed signs of hypocalcemia, confirmed biologically. Full testing disclosed the origin of the seizures: hypoparathyroidism in three patients and pseudohypoparathyroidism in the other two. In four of five patients, computed tomography showed calcification of the basal ganglia, defining Fahr's syndrome. The patients were treated with oral calcium and active vitamin D (1-alphahydroxy vitamin D3). Seizure frequency progressively decreased and serum calcium levels returned to normal. These cases illustrate the importance of the physical examination and of routine serum calcium assay in patients with new-onset epileptic seizures in order to detect hypocalcemia secondary to hypoparathyroidism.

New clinical trials with vitamin D and analogs in renal disease

Two new clinical trials highlight refinements in the use of vitamin D and its analogs in the treatment of secondary hyperparathyroidism in end-stage renal disease (ESRD), and the treatment of proteinuria in diabetics. In patients with ESRD, alfacalcidol is as effective as paricalcitol in suppressing parathyroid hormone; the occurrence of hypercalcemia and hyperphosphatemia is infrequent and similar with the two analogs. Oral cholecalciferol reduces albuminuria and urinary transforming growth factor-β1 in patients with type 2 diabetes mellitus and proteinuria.

Relation of oral 1α-hydroxy vitamin D3 to the progression of aortic arch calcification in hemodialysis patients

The role of decreased active vitamin D levels on vascular calcification has not been elucidated in hemodialysis (HD) patients. The aim of the present study was to evaluate the relationship between progression of aortic arch calcification (AoAC) and prescribed dose of 1alpha-hydroxy vitamin D. The enrolled study subjects were 65 (40 men and 25 women) HD patients. Calcification of the aortic arch was semiquantitatively estimated with a score (AoACS) on plain chest radiology. Change in AoACS (DeltaAoACS) was obtained by subtracting the baseline AoACS value from the follow-up AoACS value. The second assessment was performed from 2 years after the first determination. The nonprogressors (63.2 +/- 14.5 years) were significantly younger than the progressors (68.2 +/- 10.8 years) (P = 0.0419). In addition, prescribed dose of 1alpha-hydroxy vitamin D3 was significantly higher in the nonprogressors (125.5 +/- 109.1 microg) than progressors (84.8 +/- 81.1 microg) (P = 0.0371). Multiple regression analysis revealed prescribed dose of 1alpha-hydroxy vitamin D(3) (beta value = -0.324, P = 0.0051) as well as DBP (beta value = -0.418, P = 0.007), serum levels of P (beta value = 0.333, P = 0.006) and C-reactive protein (beta value = 0.237, P = 0.0048) to be significant independent determinants of DeltaAoACS. In conclusion, the evaluation of AoACS on chest radiography is a very simple tool in HD patients. Active vitamin D therapy seems to protect patients from developing vascular calcification.

Vitamin D Receptor Genotype in Hypophosphatemic Rickets as a Predictor of Growth and Response to Treatment

Treatment of X-linked hypophosphatemic rickets improves bone mineralization and bone deformities, but its effect on skeletal growth is highly variable. Genetic variants in the promoter region of the vitamin D receptor (VDR) gene may explain the response to treatment because this receptor mediates vitamin D action. We studied the VDR promoter haplotype structure in a large cohort of 91 patients with hypophosphatemic rickets including 62 patients receiving 1alpha-hydroxyvitamin D3 derivatives and phosphates from early childhood on. Treatment improved bone deformities and final height, but 39% of treated patients still had short stature at the end of growth (-2 sd score or below). Height was closely associated with VDR promoter Hap1 genotype. Hap1(-) patients (35% of the cohort) had severe growth defects. This disadvantageous association of Hap1(-) status with height was visible before treatment, under treatment, and on to adulthood. Gender and age at initiation of treatment could not account for the Hap1 effect. No association with growth was found with a polymorphism of the PTH receptor gene otherwise found to be associated with adult height. Compared with Hap1(+) patients, those who were Hap1(-) had a higher urinary calcium response to 1alpha-hydroxyvitamin D3 and had significantly lower circulating FGF23 levels (C-terminal assay), taking into account their phosphate and 1alpha-hydroxyvitamin D3 intakes. The present work identifies the VDR promoter genotype as a key predictor of growth under treatment with 1alpha-hydroxyvitamin D3 derivatives in patients with hypophosphatemic rickets, including those with established PHEX alterations. The VDR promoter genotype appears to provide valuable information for adjusting treatment and for deciding upon the utility of early GH therapy.

Changes in vitamin D after gastrectomy

We previously reported that the administration of 1alpha hydroxy vitamin D3 was effective for treating post-gastrectomy bone disorders. Accordingly, we performed the present study to obtain evidence supporting the effectiveness of 1alpha hydroxy vitamin D3 in post-gastrectomy patients. The study involved 22 outpatients who had undergone gastrectomy for gastric cancer and had not been treated with 1alpha hydroxy vitamin D3 or calcium. They comprised 17 men and 5 women, with a mean age of 61.9 years. Laboratory tests were performed to examine the following parameters: 1,25(OH)(2) vitamin D3; 25(OH) vitamin D3; 24,25(OH)(2) vitamin D3; ionized calcium; calcium; phosphorus; alkaline phosphatase; N-parathyroid hormone; and osteocalcin. The level of 1,25(OH)(2) vitamin D3, the most active of the vitamin D metabolites, was found to be normal in all of the patients. In contrast, the level of 25(OH) vitamin D3, which shows weak activity, was below the normal range in 7 of the 22 patients (31.8%). The mean serum level of 25(OH) vitamin D3 was significantly lower in patients at 1 year or more postoperatively than the level in those at less than 1 year postoperatively (P = 0.041), as well as being significantly lower in patients who had received total gastrectomy than in patients who underwent other gastrectomy procedures. The level of 24,25(OH)(2) vitamin D3, a metabolite of 25(OH) vitamin D3 that shows weak activity, was below the normal range in 19 of the 22 patients (86.4%). On multivariate analyses, factors associated with the change in vitamin D metabolites did not remain. The patients showed a decrease of 25(OH) vitamin D3 and 24,25(OH)(2) vitamin D3, which are metabolites that show weak activity. This suggests that a homeostatic response maintains the normal level of 1,25(OH)(2) vitamin D3, which is important for calcium regulation. Thus, it was suggested that gastrectomy had a moderate influence on the metabolism of vitamin D. However we could not detect any factor associated with the decrease of 25(OH) vitamin D3 and 24,25(OH)(2) vitamin D3.

Comparative therapeutic effects of orally administered 1,25-dihydroxyvitamin D3 and 1alpha-hydroxyvitamin D3 on type-1 diabetes in non-obese diabetic mice fed a normal-calcaemic diet

Frequent injections of the hormonal form of vitamin D(3), 1,25 dihydroxyvitamin D(3) (1,25D3) reportedly inhibits autoimmune type 1 diabetes (T1D) in non-obese diabetic (NOD) mice by correcting some of the abnormalities in antigen-presenting cells which contribute the development of pathogenic T cell responses. This route of administration greatly elevates the levels of these compounds in the bloodstream for hours after treatment, which requires mice to be fed diets formulated to contain much reduced levels of Ca to avoid the toxic effects of hypercalcaemia. In the current work, we demonstrate that feeding 1,25D3 or its synthetic precursor, 1alpha(OH) vitamin D(3) (1alphaD3), as part of a T1D supportive chow diet containing normal levels of Ca, is an effective means of reducing the incidence of disease in NOD mice, but the doses required for protection elicited hypercalcaemia. However, T1D protection elicited by D3 analogue feeding appears, at least partially, to have an immunological basis, as splenic T cells from treated mice had a decreased capacity to adoptively transfer disease. Protection is associated with an increased proportion of T cells with CD4+ forkhead box P3+ regulatory phenotype within the islet infiltrate of treated animals. The 1alphaD3 precursor is converted rapidly to the active 1,25D3 isoform in vivo. However, feeding the 1alphaD3 analogue elicited stronger T1D protection than the 1,25D3 compound, but also induced more severe hypercalcaemia. In future, the dietary supplementation of novel low-calcaemic D3 analogues may enable their continuous delivery at levels that inhibit T1D development in susceptible humans consuming normal levels of Ca.

A randomized trial of intermittent versus continuous oral alfacalcidol treatment of hyperparathyroidism in end-stage renal disease

Secondary hyperparathyroidism, a major clinical problem in patients with chronic renal failure, develops in response to phosphate retention and impaired calcitriol [1,25-dihydroxyvitamin D3] synthesis. Vitamin D therapy, particularly alfacalcidol [1 alpha-hydroxyvitamin D3], has been shown to be effective in the treatment of secondary hyperparathyroidism. The aim of this study was to compare the effect of a 12-week course of continuous versus intermittent oral alfacalcidol therapy on parathyroid hormone suppression. 34 patients were selected and randomly divided into 2 groups to receive either intermittent or continuous oral alfacalcidol. Baseline data were obtained on serum calcium, phosphorus, alkaline phosphatase and PTH. All but the PTH were monitored monthly. PTH levels were measured again until the end of the protocol. The intervention was 2 microg of alfacalcidol given after each dialysis session (intermittent group) or 1 microg given 6 days/week (continuous group). Serum calcium and phosphorus showed a tendency to increase from baseline levels in both groups. Mean PTH levels for both groups showed a progressive reduction over time during the study period. This decrement showed no significant difference with regard to the schedule of alfacalcidol administration when comparing the 2 groups. There also was no difference in the incidence of side effects--hypercalcemia and hyperphosphatemia--between the intermittent and continuous intervention. Feedback regulation of PTH with oral alfacalcidol therapy is efficient in the treatment of hyperparathyroidism. However, intermittent and continuous oral administration are equally effective in suppressing an elevated PTH level in hemodialysis patients, with similar safety margins.

Trace Determination of Steroids Causing Age-Related Diseases Using LC/MS Combined with Detection-Oriented Derivatization

With the rapid shift to an aging society in Japan, age-related diseases, such as osteoporosis, dementia and cancer, are sharply increasing. The measurement of steroids related to these diseases in biological fluids and tissues is useful for elucidation of the nature, diagnosis and treatment of such diseases. LC/MS is considered to be the most promising method for this purpose due to its specificity and versatility, but it sometimes does not demonstrate the required sensitivity for trace amounts of steroids, because steroids have a rather low response using either electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI). To overcome this problem, the author developed detection-oriented derivatization procedures for steroids in LC/MS. For ESI-MS, introduction of a permanently charged moiety is effective. Based on this, 2-hydrazino-1-methylpyridine was developed and used in monitoring prostatic 5alpha-dihydrotestosterone, a good index for the follow-up of patients affected by prostate cancer under androgen deprivation therapy and salivary dehydroepiandrosterone, which is now often designated as an anti-aging hormone. A proton-affinitive Cookson-type reagent, 4-[2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalyl)ethyl]-1,2,4-triazoline-3,5-dione, was used for the determination of 1alpha-hydroxyvitamin D3 [1alpha(OH)D3], a synthetic prodrug of the active form of vitamin D3, in human plasma, and this new LC/positive-APCI-MS method enabled the pharmacokinetic study of 1alpha(OH)D3 in humans. Electron-capture APCI-MS based on derivatization with 2-nitro-4-trifluoromethylphenylhydrazine was used for the analysis of neurosteroids, which affect brain excitability through action at the neurotransmitter receptors. With this method, the stress-induced rapid biosynthesis of pregnane-type neurosteroids in rat brains was demonstrated.

Hypocalcemia due to tubular dysfunction in a patient with holoprosencephaly

This is the first report of a case of hypocalcemia in a female infant with holoprosencephaly. Hypocalcemia developed 60 days after birth, secondary to decreased serum 1,25-dihydroxyvitamin D, as a result of renal tubular dysfunction which may have been induced by prerenal acute renal failure, the administration of anticonvulsants, and hypothyroidism. However, there was no evidence of rickets, and her serum 25-hydroxyvitamin D value was normal. She was treated with high-dose (0.5 microg/kg) 1alpha-hydroxyvitamin D3 and calcium lactate, and her calcium and 1,25-dihydroxyvitamin D values were consequently, normalized. However, she died at 268 days after birth.

Comparison of cyclic and continuous calcitonin regimens in the treatment of postmenopausal osteoporosis

We aimed to compare and evaluate the efficacies of a continuous regimen of intranasal salmon calcitonin (SCT) and two cyclic regimens (different cyclic regimens from previous studies) based on alternating 15 days or on 10 days consecutively per month for 1 year in the treatment of postmenopausal osteoporosis. We performed an open-label, prospective, randomized clinical trial. A total of 120 postmenopausal osteoporotic participants between 50 and 65 years old were randomly assigned to one of three treatment groups. Patients in group 1 (n = 40) received continuously SCT nasal spray at a dose of 200 IU/day, plus continuously 500 mg/day elementary calcium and 0.25 microg/day 1-alpha hydroxyvitamin D3, for 1 year. Patients in group 2 (n = 40) received cyclically SCT nasal spray at a dose of 200 IU/day on alternating 15 days per month, plus continuously 500 mg/day elementary calcium and 0.25 microg/day 1-alpha hydroxyvitamin D3, for 1 year. Patients in group 3 (n = 40) received cyclically SCT nasal spray on 10 days consecutively per month (20 days/month rest), plus continuously 500 mg/day elementary calcium and 0.25 microg/day 1-alpha hydroxyvitamin D3, for 1 year. Data was evaluated by repeated analysis of variance (ANOVA). In addition, statistical differences between groups were assessed by the two-tailed Student's t test. After 1 year of the study, seven patients from group 1, eight patients from group 2 and five patients from group 3 withdrew from the study. No patient discontinued the study because of adverse drug effects. There was a statistically-significant improvement in pain intensity VAS scores at the end of the year to baseline scores in all three groups (p < 0.001). There was no significant difference in pain intensity VAS scores between groups at the end of the year (p > 0.05). Lumbar and femur neck BMD scores improved significantly at the end of treatment in all three groups (p < 0.05). There was no statistically-significant difference in BMD scores between groups at final (p > 0.05). Urinary DPD/Cre levels decreased significantly in all three groups by the end of the year (p < 0.05). There was no statistically-significant difference in urinary DPD/Cre final levels between groups (p > 0.05). According to the results of the present study, consecutive 10 days therapy with SCT, which is the first in the literature to our knowledge, is as effective as the other two regimens in the treatment of osteoporosis. Both cyclic regimens in our study (alternating 15 days and 10 consecutive days each month for 1 year) do appear to offer some advantages, especially economically and clinically, as compared to continuous treatment.

Identification of a Novel Rat Microsomal Vitamin D3 25-Hydroxylase

Vitamin D3 requires the 25-hydroxylation in the liver and the subsequent 1alpha-hydroxylation in the kidney to exert its biological activity. Vitamin D3 25-hydroxylation is hence an essential modification step for vitamin D3 activation. Until now, three cytochrome P450 molecular species (CYP27A1, CYP2C11, and CYP2D25) have been characterized well as vitamin D3 25-hydroxylases. However, their physiological role remains unclear because of their broad substrate specificities and low activities toward vitamin D3 relative to other substrates. In this study, we purified vitamin D3 25-hydroxylase from female rat liver microsomes. The activities of the purified fraction toward vitamin D3 and 1alpha-hydroxyvitamin D3 were 1.1 and 13 nmol/min/nmol of P450, respectively. The purified fraction showed a few protein bands in a 50-60-kDa range on SDS-PAGE, typical for a cytochrome P450. The tryptic peptide mass fingerprinting of a protein band (56 kDa) with matrix-assisted laser desorption ionization/time of flight mass spectrometry identified this band as CYP2J3. CYP2J3 was heterologously expressed in Escherichia coli. Purified recombinant CYP2J3 showed strong 25-hydroxylation activities toward vitamin D3 and 1alpha-hydroxyvitamin D3 with turnover numbers of 3.3 and 22, respectively, which were markedly higher than those of P450s previously characterized as 25-hydroxylases. Quantitative PCR analysis showed that CYP2J3 mRNA is expressed at a level similar to that of CYP27A1 without marked sexual dimorphism. These results strongly suggest that CYP2J3 is the principal P450 responsible for vitamin D3 25-hydroxylation in rat liver.

CYP3A4 is a human microsomal vitamin D 25-hydroxylase.

The human hepatic microsomal vitamin D 25-hydroxylase protein and gene have not been identified with certainty. Sixteen hepatic recombinant microsomal enzymes were screened for 25-hydroxylase activity; 11 had some 25-hydroxylase activity, but CYP3A4 had the highest activity. In characterized liver microsomes, 25-hydroxylase activity correlated significantly with CYP3A4 testosterone 6beta-hydroxylase activity. Activity in pooled liver microsomes was inhibited by known inhibitors of CYP3A4 and by an antibody to CYP3A2. Thus, CYP3A4 is a hepatic microsomal vitamin D 25-hydroxylase. Studies were performed to identify human microsomal vitamin D-25 hydroxylase. Sixteen major hepatic microsomal recombinant enzymes derived from cytochrome P450 cDNAs expressed in baculovirus-infected insect cells were screened for 25-hydroxylase activity with 1alpha-hydroxyvitamin D2 [1alpha(OH)D2], 1alpha-hydroxyvitamin D3 [1alpha(OH)D3], vitamin D2, and vitamin D3 as substrates. Activity was correlated with known biological activities of enzymes in a panel of 12 characterized human liver microsomes. The effects of known inhibitors and specific antibodies on activity also were determined. CYP3A4, the most abundant cytochrome P450 enzyme in human liver and intestine, had 7-fold greater activity than that of any of the other enzymes with 1alpha(OH)D2 as substrate. CYP3A4 25-hydroxylase activity was four times higher with 1alpha(OH)D2 than with 1alpha(OH)D3 as substrate, was much less with vitamin D2, and was not detected with vitamin D3. 1alpha(OH)D2 was the substrate in subsequent experiments. In a panel of characterized human liver microsomes, 25-hydroxylase activity correlated with CYP3A4 testosterone 6beta-hydroxylase activity (r = 0.93, p < 0.001) and CYP2C9*1 diclofenac 4'-hydroxylase activity (r = 0.65, p < 0.05), but not with activity of any of the other enzymes. Activity in recombinant CYP3A4 and pooled liver microsomes was dose-dependently inhibited by ketoconazole, troleandomycin, isoniazid, and alpha-naphthoflavone, known inhibitors of CYP3A4. Activity in pooled liver microsomes was inhibited by antibodies to CYP3A2 that are known to inhibit CYP3A4 activity. CYP3A4 is a vitamin D 25-hydroxylase for vitamin D2 in human hepatic microsomes and hydroxylates both 1alpha(OH)D2 and 1alpha(OH)D3.

Lower risk for cardiovascular mortality in oral 1alpha-hydroxy vitamin D3 users in a haemodialysis population.

Renal failure results in deficiency of active vitamin D3 that has diverse effects on metabolism and organ functions. Treatment with active forms of vitamin D(3) ameliorates abnormalities in bone and mineral metabolism, cardiac function, immune response and others. We hypothesized that treatment with vitamin D(3) may be beneficial for survival in patients with end-stage renal disease (ESRD). We compared the risk of death between regular users (n = 162) and non-users (n = 80) of oral 1alpha-hydroxyvitamin D3 (alfacalcidol) in a cohort of ESRD patients undergoing haemodialysis for a follow-up of 61 +/- 23 months. The daily dose of alfacalcidol ranged from 0.25 to 1.5 microg, with a median of 0.5 microg. The alfacalcidol users showed a lower risk of death from cardiovascular disease than the non-users in a univariate Cox model [hazards ratio (HR) 0.287, 95% confidence interval (CI) 0.127-0.649, P = 0.003], whereas the risk for death from non-cardiovascular disease was not different between the two groups. Stepwise multivariate Cox analysis showed that cardiovascular mortality was significantly associated with age, presence of diabetes mellitus and treatment with alfacalcidol (HR 0.377, 95% CI 0.246-0.578, P = 0.022). These results indicate that use of oral alfacalcidol was associated with reduced risk for cardiovascular death in this cohort of ESRD patients. The result of this observational study warrants further randomized controlled trials with 1alpha-hydroxy vitamin D3 to confirm the possibility that such medication improves survival of ESRD patients.

Treatment with vitamin D3 and/or vitamin K2 for postmenopausal osteoporosis.

It is established in Japan that treatment with 1alpha-hydroxyvitamin D3 (alfacalcidol) slightly reduces bone turnover, sustains lumbar bone mineral density (BMD), and prevents osteoporotic vertebral fractures in postmenopausal women with osteoporosis, while vitamin K2 (menatetrenone) enhances gamma-carboxylation of bone glutamic acid residues and secretion of osteocalcin, sustains lumbar BMD, and prevents osteoporotic fractures in patients with osteoporosis. Available evidence suggests that the effect of vitamin K2 on mineralization by human periosteal osteoblasts is enhanced in the presence of 1,25 dihydroxyvitamin D3 in vitro. The effect of vitamin K2 on BMD in ovariectomized rats is affected by the plasma 25-hydroxyvitamin D3 level in vivo, and is significant only when rats are fed a diet containing vitamin D3. Based on this line of evidence, combined treatment with alfacalcidol and menatetrenone for osteoporosis is surmised to be more effective than treatment with menatetrenone alone, and may have anabolic effects on osteoporotic bone. This combined treatment may increase bone formation as well as bone resorption over the mild anti-resorptive effect of alfacalcidol itself, and shows the greatest effect on lumbar BMD or the incidence of vertebral fractures in studies in which the mean age and years since menopause of subjects were low and the degree of osteoporosis was mild. It may be effective for mild postmenopausal osteoporosis in which age-related deterioration of trabecular bone properties remains below the threshold for vertebral fractures, even if bone resorption is increased and trabecular bone has deteriorated.

Altered bone turnover in chlorpromazine-challenged rats and its effect on 1alpha-hydroxyvitamin D3 administration in vivo.

We reported previously that Ca and Pi levels are elevated and alkaline phosphatase (ALP) activity and 1alpha,25(OH)2D3 levels are reduced in chlorpromazine (CPZ)-challenged rats. In the present study, we determined the serum levels of interleukin (IL)-6 and acid phosphatase (ACP) in CPZ-challenged rats, in addition to levels of ALP protein. ALP mRNA and coccyx morphology were examined in CPZ-challenged rats as well as the effect of CPZ on 1alpha(OH)D3 production in vivo. Although Ca, Pi, IL-6, and ACP activity levels in CPZ-challenged rats were markedly increased on day 30, the elevated serum levels were restored to within normal ranges by the in vivo addition of 1alpha(OH)D3 to CPZ administration. The gain in body weight in CPZ-treated rats was significantly improved by the addition of 1alpha(OH)D3. Reduced levels of 1alpha,25(OH)2D3 in CPZ-treated rats were restored to normal levels by the administration of 1alpha(OH)D3. Moreover, the decreased ALP activity and ALP mRNA levels in the rat coccyx marrow in CPZ-treated rats were also restored by the administration of 1alpha(OH)D3 with CPZ. However, the molecular sizes of rat ALP molecules and ALP mRNA were the same for each group. Furthermore, bone morphometry showed that trabecular bone in the rat coccyx was decreased in CPZ-treated rats. However, the reduced volume of trabecular bone in CPZ-treated rats was restored by the addition of 1alpha(OH)D3 to CPZ administration. Taken together, altered bone metabolism in CPZ-treated rats can be improved by the addition of 1alpha(OH)D3.

1alpha-Hydroxyvitamin D3 suppresses trabecular bone resorption by inhibiting osteoclastogenic potential in bone marrow cells after ovariectomy in mice.

To test the hypothesis that 1alpha-hydroxyvitamin D3 (1alpha(OH)D3) suppresses bone resorption after ovariectomy (ovx) by inhibiting osteoclastogenic potential in bone marrow cells, the bilateral tibiae of ddY mice, 8 weeks of age, subjected to ovx were obtained. 1alpha(OH)D3, at doses of 0, 0.2 (low dose), or 0.4 microg/kg body weight (high dose), was administered orally by canula three times a week for 2 or 6 weeks. Histomorphometric analysis of the proximal tibiae revealed that 1alpha(OH)D3 administration had no significant effect on trabecular bone volume of ovx limbs, which was reduced after ovx. The bone formation rate, increased by ovx, was significantly decreased by the administration of high-dose 1alpha(OH)D3. The ovx-induced increases in osteoclast number and surface at 2 weeks postsurgery were suppressed by the administration of high-dose 1alpha(OH)D3. With regard to bone marrow cells, the number of nonadherent cells per tibia obtained from ovx limbs increased, and this increase was suppressed by the administration of low- and high-dose 1alpha(OH)D3. The formation of mineralized nodules in marrow cultures obtained from ovx limbs was increased after surgery and unaltered by 1alpha(OH)D3 administration. The number of osteoclast-like multinucleated cells obtained from ovx limbs was reduced by low- and high-dose 1alpha(OH)D3 administration alike. The number of colony forming units-fibroblast and the number of colony forming units for granulocytes and macrophages was unaltered by ovx or the administration of 1alpha(OH)D3. The present study clearly demonstrates that high-dose 1alpha(OH)D3 suppresses osteoclast numbers and surface after ovx. The inhibitory effects of low- and high-dose 1alpha(OH)D3 on bone marrow cells after ovx were marked in the differentiation from osteoclast precursors to mature osteoclasts. Administration of 1alpha(OH)D3 suppressed ovx-promoted trabecular bone resorption by inhibiting osteoclastogenic potential in bone marrow cells.

Cytochrome P450 enzymes in the bioactivation of vitamin D to its hormonal form (review).

The formation of 1alpha,25-dihydroxyvitamin D3 requires a 25-hydroxylation followed by a 1alpha-hydroxylation catalyzed by cytochrome P450 (CYP) enzymes in liver and kidney. The aim of this review is to give a brief summary of our research on the cytochrome P450 enzymes catalyzing the 25-hydroxylation and 1alpha-hydroxylation and to discuss the results in relation to other published literature on these enzymes. Two hepatic P450 enzymes catalyzing 25-hydroxylation of vitamin D3 exist in mammalian liver - one mitochondrial and one microsomal. The mitochondrial vitamin D3 25-hydroxylase is apparently identical with CYP27A, an obligatory enzyme in bile acid biosynthesis in liver. The microsomal 25-hydroxylase has been purified to apparent homogeneity from pig liver. The enzyme catalyzed 25-hydroxylation of vitamin D3, 1alpha-hydroxyvitamin D3, vitamin D2 and 1alpha-hydroxyvitamin D2. A cDNA encoding pig liver microsomal vitamin D3 25-hydroxylase has been isolated in this laboratory. The primary structure of vitamin D3 25-hydroxylase shows 70-80% identity with members of the CYP2D subfamily and has been designated CYP2D25. Three different 1alpha-hydroxylating cytochromes P450 in kidney, i.e. CYP27A, CYP27B and a microsomal 1alpha-hydroxylase, have been described. Mitochondrial cytochrome P450, catalyzing 1alpha-hydroxylation and 27-hydroxylation but not 24-hydroxylation of 25-hydroxyvitamin D3, was partially purified from pig kidney. Purification and inhibition experiments as well as experiments with a monoclonal antibody against CYP27A indicated that one single enzyme catalyzes both 1alpha- and 27-hydroxylation. Treatment of rats with a single i.v. dose of 1alpha,25-dihydroxyvitamin D3 resulted in a marked suppression of CYP27A mRNA levels in kidney. The results suggest a role for CYP27A as a renal mitochondrial 1alpha-hydroxylase. Subsequently, several research groups reported the isolation of cDNA encoding mouse, rat and human kidney 25-hydroxyvitamin D3 1alpha-hydroxylase. The amino acid sequences deduced from these cDNA clones were similar but differed from that of CYP27A. This 1alpha-hydroxylase constitutes a new CYP27 subfamily, CYP27B. The expression of CYP27B was found to be influenced by vitamin D status and parathyroid hormone. Mutations in the CYP27B gene have been identified in patients with pseudovitamin D-deficiency rickets. A microsomal P450 catalyzing 1alpha-hydroxylation of 25-hydroxyvitamin D3 has been purified to apparent homogeneity from pig kidney. This finding demonstrate the presence of a microsomal 1alpha-hydroxylase in addition to the mitochondrial 1alpha-hydroxylases in kidney. The relative importance and regulation of the different renal 1alpha-hydroxylases in the bioactivation of vitamin D3 under normal and pathological conditions will be subject for future studies.

A concise enantioselective synthesis of a key A-ring synthon for 1 alpha-hydroxyvitamin D3 compounds.

[figure: see text] This report describes a concise enantioselective synthesis of the A-ring synthon for the synthesis of 1 alpha-hydroxyvitamin D3 compounds. The synthesis involves two notable transformations: (I) stereoselective construction of the enol triflate from the vinyl ketone by Michael addition of Ph2P(O)Li followed by in situ triflation of the resulting enolate and (II) palladium-catalyzed Heck type cyclization of the enol triflate.