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At least 19 recordsLinked to original sources
PubMed1976

Calcifediol in chronic renal insufficiency. Skeletal response.

Quantitative histology of thin, nondecalcified sections was performed on sequential bone biopsy specimens from five patients undergoing long-term hemodialysis and treated with calcifediol (25-hydroxycholecalciferol) for periods of three to nine months. With increase of intestinal absorption of calcium and decline of circulating immunoreactive parathyroid hormone and alkaline phosphatase, the bones of each patient exhibited striking histological improvement. The group as a whole showed statistically significant decreases in osteoclast number and in the percentages of osteoid surface covered by active osteoblasts. Marrow fibrosis was either eliminated or strikingly decreased in each patient. Osteoid volume significantly declined in four of five patients. In patients with osteitis fibrosa as the predominant histological lesion, calcifediol therapy resulted in decreased calcification front activity. Increased activity was the result when osteomalacia predominated.

Adult↗
PubMed1992

Effects of long-term cholestyramine administration on vitamin D and parathormone levels in middle-aged men with hypercholesterolemia.

The objective of this study was to evaluate possible adverse effects of long-term bile acid-binding resin (cholestyramine) treatment on vitamin D, parathyroid hormone, and calcium levels in middle-aged men. A double-blind randomized clinical trial was carried out over a period of 7 to 10 years at the University of Minnesota's Lipid Research Clinic as part of the Lipid Research Clinic's Coronary Primary Prevention Trial. Two hundred and sixty-eight men aged 42 to 68 years who had been previously randomized in the CPPT to cholestyramine or placebo and who had taken at least 75% of the prescribed study medication (6 packets or 24 gm/day) as determined by packet counts for the duration of the Coronary Primary Prevention Trial including the last 4 months of the trial were studied: one group (n = 124) received cholestyramine and the other group (n = 144) received a corresponding dose of placebo. Serum samples were obtained at the time of the final study visit in cholestyramine and placebo groups. (Results are reported as mean +/- SD in SI units). There were no differences in plasma levels of calcium (2.3 +/- 0.1 mmol/L vs 2.3 +/- 0.1 mmol/L), phosphorus (0.99 +/- 0.14 mmol/L vs 0.98 +/- 0.12 mmol/L), albumin (45 +/- 3 gm/L vs 46 +/- 0.6 gm/L), calcifediol (62.6 +/- 29.2 nmol/L vs 63.4 +/- 28.4), 25(OH)D2 (14 +/- 11 nmol/L vs 12 +/- 10 nmol/L) or calcitriol (99 +/- 190 pmol/L vs 91 +/- 56 pmol/L).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1991

How much vitamin D for neonates?

To assess the adequacy of different dosages of neonatal vitamin D, 25-hydroxyvitamin D serum concentrations were longitudinally monitored in 27 low-birth-weight and 25 full-term well infants from birth to 16 weeks after delivery. The infants were randomly assigned to receive either 10 micrograms/d (400 IU/d) or 20 micrograms/d (800 IU/d) of vitamin D or 0.85 or 1.5 micrograms/d of 25-hydroxyvitamin D3. In each infant who received 10 or 20 micrograms/d of vitamin D 25-hydroxyvitamin D, serum concentrations greater than 20 ng/mL were maintained, with some low-birth-weight infants reaching 60-ng/mL concentrations. Similarly, in the low-birth-weight infants receiving 1.5 and 0.85 micrograms/d of 25-hydroxyvitamin D3, serum 25-hydroxyvitamin D levels greater than 12 ng/mL were maintained. In the full-term infants who received 1.5 micrograms/d of 25-hydroxyvitamin D3, serum 25-hydroxyvitamin D concentrations of greater than 12 ng/mL were maintained, but in those who received 0.85 micrograms/d, serum 25-hydroxyvitamin D concentrations of 10 ng/mL could not be maintained. These vitamin D status data document that 10 micrograms (400 IU) of vitamin D represents a sufficient daily intake for both premature and full-term well infants. These data also indicate that while as little as 0.85 micrograms/d of 25-hydroxyvitamin D3 may facilitate vitamin D sufficiency in low-birth-weight neonates, it does not do so in full-term infants.

Administration, Oral↗
PubMed1991

Analysis of vitamin D and its metabolites using thermospray liquid chromatography/mass spectrometry.

A new method is described for the analysis of vitamin D and its metabolites utilizing thermospray (TSP) mass spectrometry as an on-line detector for high performance liquid chromatography. Ionization conditions were optimized for use with isocratic reversed phase chromatography. TSP mass spectrometry was employed in series with a UV absorbance detector to facilitate comparisons between the two methods of detection. Positive ion TSP mass spectra were recorded for vitamin D2, vitamin D3, 25-hydroxyvitamin D3 (25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3). The spectra contained protonated molecular ions, ammonium adduct ions and fragment ions due to the loss of one or more molecules of water. A comparison of quantitative precision was made by determining UV absorbance and TSP standard curves for vitamin D3 using two different methods: (1) External standard method with post-column (post UV detector) addition of ammonium acetate. (2) As (1) but using the method of internal standards with a closely eluting internal standard (vitamin D2). In each case the quantitative precision (correlation coefficient) for UV absorbance detection was superior owing to intrinsic instability of the TSP ion beam. A stable isotopically labelled internal standard was employed in the development of an assay for 1,25(OH)2D3. The assay was used to quantify in vitro enzymic conversion of 25(OH)D3 to 1,25(OH)2D3 in guinea pig and sheep renal mitochondrial incubations. TSP LC/MS was also applied to analysis of an extract of human blood plasma in which D3 and each of its principal metabolites were identified in a single analysis.

24,25-Dihydroxyvitamin D 3↗
PubMed2026

Comparison of Traditional Chinese Exercise and Equipment-Based Exercise on Glycaemic Control and Vitamin D Levels in Middle-Aged and Elderly Patients With Prediabetes: A Randomised Controlled Trial.

BACKGROUND: Prediabetes is a critical window for preventing progression to type 2 diabetes mellitus (T2DM). Both vitamin D deficiency and physical inactivity are associated with impaired glucose metabolism. This study compared the effects of Traditional Chinese Exercise (TCE) and Kuanle Equipment Exercise (KEE) on glycaemic measures, lipid profiles, body composition and serum 25-hydroxyvitamin D3 [25(OH)D3] in middle-aged and elderly adults with prediabetes. METHODS: We conducted a 12-week, single-centre, randomised controlled trial involving 62 participants with prediabetes (mean age 55.2 ± 8.4 years; 88.7% female). Participants were randomly assigned to control (usual care, n = 21), TCE (n = 20), or KEE (n = 21). Primary outcomes included fasting plasma glucose (FPG), 2-h OGTT glucose, glycated haemoglobin (HbA1c) and serum 25(OH)D3. Secondary outcomes comprised triglycerides, total cholesterol, LDL-C, HDL-C and body composition. RESULTS: At baseline, mean serum 25(OH)D3 was 21.53 ± 3.90 nmol/L. At 12 weeks, both TCE and KEE improved FPG, 2-h OGTT glucose, HbA1c and 25(OH)D3 versus control (all p ≤ 0.001). Relative changes in FPG were -9.4% (TCE) and -15.2% (KEE) versus -1.5% (control); corresponding changes were -14.6% and -21.2% for 2-h OGTT glucose, -6.7% and -12.9% for HbA1c, and +60.6% and +81.9% for 25(OH)D3. Direct TCE-KEE comparisons were not significant (all p > 0.05). In an exploratory analysis, change in 25(OH)D3 was inversely associated with change in 2-h OGTT glucose (partial r = -0.358, p = 0.006), but not with FPG, HbA1c, or triglycerides. CONCLUSIONS: Both TCE and KEE improved glycaemic outcomes and increased serum 25(OH)D3 compared with usual care in middle-aged and elderly adults with prediabetes. Although KEE produced numerically larger estimates, direct between-group comparisons were not significant, and the superiority of KEE over TCE was not established. These vitamin D findings require confirmation in trials that quantify sunlight exposure and dietary vitamin D intake.

Aged↗
PubMed1991

In micronodular cirrhosis, hepatocytes retain a normal C-25 hydroxylation capacity toward vitamin D3: a study using the rat carbon tetrachloride-induced cirrhotic model.

To test further the competence of the cirrhotic liver to metabolize vitamin D3 at C-25, hepatocytes were isolated from controls and from CCl4-induced cirrhotic rat livers, as well as from partially hepatectomized rats. The transformation of D3 into 25-hydroxyvitamin D3 was studied in the presence of 10(7) hepatocytes at D3 concentrations of 20 nmol/L to 15.4 mumol/L. Histologically, micronodular cirrhosis was present in all CCl4-treated rats, whereas controls had normal livers; portal venous pressure (p less than 0.008) and intrahepatic collagen content (p less than 0.0001) were significantly increased in CCl4-treated rats, whereas no difference was found between the two groups in the total and ionized serum calcium, D3 metabolites, ALT, AST and alkaline phosphatase. Cytochrome P-450 was 0.27 +/- 0.02 and 0.25 +/- 0.02 nmol/10(6) hepatocytes in controls and cirrhotic rats (N.S.), and it significantly increased in both groups after phenobarbital or 3-methylcholanthrene administration (p less than 0.0001). 25-Hydroxyvitamin D3 formation was best described by power law equations and varied between 0.02 +/- 0.0004 and 29.57 +/- 2.8 in controls, and 0.024 +/- 0.0004 and 32.0 +/- 7.0 pmol.hr-1.10(6) hepatocytes-1 in cirrhotic rats. No statistically significant difference was found in the slopes of the 25-hydroxyvitamin D3 formation, but the y-axis intercept was found to be lower in cirrhotic rats under basal resting conditions (p less than 0.005). Inducers of the mixed function oxidases significantly increased 25-hydroxyvitamin D3 formation in controls as well as in cirrhotic rats (p less than 0.005). Moreover, both groups were found to respond similarly to the addition of modulators of the enzyme such as the calcium ionophore A23187 and parathyroid hormone. Partial hepatectomy was also without effect on the activation of D3. Furthermore, the cell sequestration of D3 was also found to be unperturbed in hepatocytes obtained from either cirrhotic or partially hepatectomized livers. The data indicate that in well-compensated micronodular cirrhosis, the C-25 hydroxylation of D3 is generally intrinsically normal at the cellular level and that it also remains fully responsive to in vivo and in vitro modulators of its activity.

Animals↗
PubMed1991

Evidence for nonrenal synthesis of 1,25-dihydroxyvitamin D in patients with inflammatory arthritis.

The extrarenal synthesis of 1,25-dihydroxyvitamin D [1,25-(OH)2D] is a characteristic of activated macrophages and has been demonstrated to occur in vitro in synovial fluid macrophages from patients with inflammatory arthritis. To examine whether such synthesis occurs in vivo, 19 patients with rheumatoid arthritis, 5 patient controls, and 5 healthy controls received a challenge oral dose of 250 micrograms 25-hydroxyvitamin D3 (25-OHD3) and the serum 1,25-(OH)2D3 response was measured. The median rise in serum 1,25-(OH)2D3 was significantly greater (22 pg/ml) in the rheumatoid patients compared to either of the control groups (8 pg/ml), although the increase in precursor 25-OHD3 was similar in all groups. The serum 1,25-(OH)2D concentration did not rise above the normal upper limit in any of the control subjects but exceeded the normal range in 8 of the rheumatoid patients. Extrarenal 1,25-(OH)2D synthesis is substrate dependent, unlike renal 1 alpha-hydroxylation, which is homeostatically controlled. Excessive 1,25-(OH)2D3 synthesis in the rheumatoid group on raising the 25-OHD3 concentration is indicative of nonrenal production of the hormonal metabolite. Further evidence for substrate-dependent extrarenal synthesis came from measurements of 25-OHD and 1,25-(OH)2D in paired serum and synovial fluid samples from 19 patients with inflammatory arthritis, including 15 with rheumatoid arthritis. Synovial fluid 1,25-(OH)2D was usually present at a lower concentration than serum 1,25(OH)2D, with which it was strongly correlated (Kendall's R = 0.46, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Chronic adaptation of dog parathyroid function to a low-calcium-high-sodium-vitamin D-deficient diet.

The development of secondary hyperparathyroidism was studied in relation to changes in serum ionized Ca (Ca2+), 25-OHD, and 1,25-(OH)2D concentrations in six dogs maintained on a low-Ca (0.05%), high-Na (1.6%), and vitamin D-deficient diet for 91 weeks. Blood samples and evaluations of the parathyroid function were obtained before and after 3, 12, 24, 36, and 91 weeks of diet. Serum iPTH was measured by an intact hormone (I) and a carboxy-terminal (C) assay. The sigmoidal relationship between ionized Ca and iPTH values was evaluated mathematically. Results are means +/- SD. Statistically significant changes over a time period were evaluated by an ANOVA for repeated measurements. Over the first 3 weeks, serum Ca2+, 25-OHD, and 1,25-(OH)2D did not change but stimulated I-iPTH increased 84.3 +/- 39.9% (p less than 0.005) and C-iPTH only 25.3 +/- 12.2% (p less than 0.01), a significant difference (p less than 0.02). The increase in stimulated I-iPTH reached 487.4 +/- 139.6% (p less than 0.0001) and 418.4 +/- 76.9% (p less than 0.0001) for C-iPTH by the end of the study. Similar significant increases were seen in basal and nonsuppressible iPTH at or after week 12.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Biochemical parameters associated with low bone density in healthy men and women.

A causal role in age-related bone loss has been attributed to alterations in vitamin D status, the bone mineral regulating hormones, and/or renal function. We assessed biochemical parameters of bone metabolism and renal function in healthy subsets of young and old men (n = 191) and women (n = 120) and evaluated the relationships between these parameters and bone mineral density (BMD) in the radius, spine, and femur. There were no significant associations between BMD at any site and serum 25-OHD, 1,25-(OH)2D, PTH, or creatinine clearance in either young men or in young or old women, after controlling for age. In old men, however, lower radius BMD was significantly related to higher PTH and higher 1,25-(OH)2D and marginally related to lower 25-OHD values. In young men, there were unexpected but significant associations between lower femoral neck BMD and higher serum osteocalcin and urinary calcium/creatinine excretion after age adjustment. In old women, lower spine and radius BMD was also significantly correlated with higher serum osteocalcin. In this healthy, vitamin D-replete population, there were significant cross-sectional declines in BMD in the femur in young and old men and at all sites in old women. Elevated remodeling may be an important feature that contributes to reduced femoral BMD in young men and reduced spine and radius BMD in old women. However, compromised renal function or levels of 1,25-(OH)2D or elevated PTH appear to be neither necessary nor relevant as determinants of osteopenia in the spine or femur in these normal, healthy men and women.

Adult↗
PubMed1992

Transformation of vitamin D3 to 1 alpha,25-dihydroxyvitamin D3 via 25-hydroxyvitamin D3 using Amycolata sp. strains.

To enzymatically synthesize active metabolites of vitamin D3, we screened about 500 bacterial strains and 450 fungal strains, of which 12 strains were able to convert vitamin D3 to 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] via 25-hydroxyvitamin D3 [25(OH)D3]. The conversion activity was only detected in strains belonging to the genus Amycolata among all the organisms tested. A preparative-scale conversion of vitamin D3 to 25(OH)D3 and 1 alpha,25(OH)2D3 in a 200-1 tank fermentor using A. autotrophica FERM BP-1573 was accomplished, yielding 8.3 mg 25(OH)D3/l culture and 0.17 mg 1 alpha,25(OH)2D3/l culture. A related compound, vitamin D2, could be also converted to 25-hydroxyvitamin D2 and 1 alpha,25-dihydroxyvitamin D2 using the same strain. The cytochrome P-450 of FERM BP-1573 was detected by reduced CO difference spectra in whole-cell suspensions. Vitamin D3 in the culture induced cytochrome P-450 and the conversion activity simultaneously, suggesting that the hydroxylation at C-25 of vitamin D3 and at C-1 of 25(OH)D3 originates from cytochrome P-450.

Actinomycetales↗
PubMed1992

Disturbed calcium metabolism in subjects with elevated diastolic blood pressure.

Essential hypertension has been associated with disturbed calcium metabolism, but the available data are controversial. We measured parameters of calcium metabolism in groups of untreated male subjects (n = 78) with elevated diastolic blood pressure (101 +/- 6 mmHg, mean +/- SD) and age-matched male subjects (n = 79) with low diastolic blood pressure (62 +/- 4 mmHg). The participants of the study were drawn from a random population sample. Subjects with high diastolic blood pressure had significantly higher carboxy-terminal parathyroid hormone (PTH) plasma concentrations than controls with low diastolic blood pressure (median 114 vs. 43 pmol/l, P less than 0.01). The 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D concentrations were comparable in both groups. Individuals with high diastolic blood pressure had significantly lower total serum calcium (2.41 +/- 0.10 vs. 2.47 +/- 0.10 mmol/l, mean +/- SD; P less than 0.01). PTH concentrations were correlated with diastolic pressure (r = -0.39, P less than 0.001). The data are compatible with increased parathyroid activity despite unchanged concentrations of vitamin D metabolites in human hypertension.

Adult↗
PubMed1992

Long-term therapy with cyclosporin A does not influence serum concentrations of vitamin D metabolites in patients with multiple sclerosis.

Animal studies have shown that cyclosporin A (CyA) stimulates renal 25-hydroxyvitamin D3 [25(OH)D3]-1 alpha-hydroxylase activity; in contrast, studies in renal transplant recipients indirectly suggest that CyA reduces 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] production. To clarify the effect of CyA on vitamin D metabolite concentrations, we measured parameters of calcium metabolism in 37 CyA-treated patients (median trough whole blood levels 171-222 ng/ml) with multiple sclerosis and initially normal kidney function. The patients participated in a randomized double-blind study to assess the efficacy of CyA in multiple sclerosis. An age- and sex-matched control group (n = 39) received azathioprine (Aza). Measurements were made at the end of a 2-year treatment period. The 1,25(OH)2D3 serum concentrations were not significantly different between the two groups, although they were numerically lower in CyA-treated patients [median (range), 28.4 pg/ml (7.8-85.9) vs 41.0 pg/ml (9.2-105.1) in Aza-treated patients]. The 25(OH)D3 levels were comparable in both groups. There was no correlation between the 25(OH)D3 and 1,25(OH)2D3 concentrations. The renal function in both groups was stable in the last 6 months of the study. At the end of the study period, the endogenous creatinine clearance was significantly lower in the CyA-treated group (85 +/- 17 ml/min versus 99 +/- 22 in the Aza-treated group, P less than 0.05). The carboxyterminal parathyroid hormone (C-PTH) was within the normal range in both groups, although CyA-treated patients had significantly higher concentrations (P less than 0.01). The urinary excretion of mineral ions, cations and protein was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Serum intact parathyroid hormone levels in elderly Chinese females with hip fracture.

Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25(OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture.

Aged↗