scholarly journals Impaired stimulation of 25-hydroxyvitamin D-24-hydroxylase in fibroblasts from a patient with vitamin D-dependent rickets, type II. A form of receptor-positive resistance to 1,25-dihydroxyvitamin D3.

1983 ◽  
Vol 72 (4) ◽  
pp. 1190-1199 ◽  
Author(s):  
J E Griffin ◽  
J E Zerwekh
Keyword(s):  
Vitamin D ◽  
Type Ii ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D3 ◽  
25 Hydroxyvitamin D ◽  
Stimulation Of

Expression of the renal 25-hydroxyvitamin D-24-hydroxylase gene: regulation by dietary phosphate

1996 ◽  
Vol 271 (1) ◽  
pp. F203-F208 ◽  
Author(s):  
S. Wu ◽  
J. Finch ◽  
M. Zhong ◽  
E. Slatopolsky ◽  
M. Grieff ◽  
...  
Keyword(s):  
Vitamin D ◽  
Gene Regulation ◽  
Mrna Level ◽  
Catabolic Pathway ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Pi Homeostasis ◽  
1,25 Dihydroxyvitamin D3 ◽  
Dietary Phosphate ◽  
25 Hydroxyvitamin D

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] plays a key role in phosphate (Pi) homeostasis through its phosphatemic actions on intestine and bone. In turn, dietary Pi restriction increases serum 1,25(OH)2D3 by stimulating its production, but its effect on vitamin D catabolism is less clear. Here we have examined the effects of dietary Pi on the expression of the renal vitamin D-24-hydroxylase (24-OHase), the first enzyme in the catabolic pathway for vitamin D compounds. Rats fed a low Pi (0.02% P) diet showed a fivefold decrease in renal 24-OHase mRNA compared with rats fed a normal Pi (0.67% P) diet. 24-OHase mRNA and 24-OHase activity decreased within 24 h of Pi restriction, reached a minimum by 48 h, and remained low through 14 days. Decreased 24-OHase mRNA was observed with more moderate Pi restriction (0.2% P), but higher Pi (1.2% P) did not increase 24-OHase mRNA over the 0.8% P diet. 24-OHase mRNA correlated well with plasma Pi (r = 0.862, P < 0.001). In conclusion, renal 24-OHase expression is regulated by dietary phosphate at the mRNA level.

scholarly journals Severe Deficiency of 1,25-Dihydroxyvitamin D3 in Human Immunodeficiency Virus Infection: Association with Immunological Hyperactivity and Only Minor Changes in Calcium Homeostasis

1998 ◽  
Vol 83 (11) ◽  
pp. 3832-3838 ◽  
Author(s):  
Charlotte J. Haug ◽  
Pål Aukrust ◽  
Egil Haug ◽  
Lars Mørkrid ◽  
Fredrik Müller ◽  
...  
Keyword(s):  
Vitamin D ◽  
Human Immunodeficiency Virus ◽  
Nutritional Status ◽  
Serum Calcium ◽  
Serum Levels ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D3 ◽  
Immunodeficiency Virus ◽  
25 Hydroxyvitamin D

The serum level of 1,25-dihydroxyvitamin D3[ 1,25-(OH)2D], the biologically most potent metabolite of vitamin D, is tightly regulated within narrow limits in human healthy adults. 1,25-(OH)2D deficiency is rare and is associated with disturbances in calcium and bone metabolism. We have previously reported a marked decrease in serum levels of 1,25-(OH)2D in human immunodeficiency virus (HIV)-infected patients. The present study was designed to further examine the causes and consequences of severe 1,25-(OH)2D deficiency in these patients. The design was a prospective cohort study. Fifty-four HIV-infected patients clinically classified according to the revised criteria from Centers for Disease Control and Prevention and healthy controls were studied. Parameters related to vitamin D and calcium metabolism as well as immunological and nutritional status were determined. Twenty-nine of the patients (54%) had serum levels of 1,25-(OH)2D below the lower reference limit, and 18 of these had undetectable levels. In contrast, HIV-infected patients had normal serum levels of 25-hydroxyvitamin D and vitamin D-binding protein. HIV-infected patients as a group had modestly depressed serum calcium and PTH levels. There were, however, no correlations between these parameters and serum levels of 1,25-(OH)2D. There were no differences in serum calcium or PTH levels or nutritional status when patients with severe 1,25-(OH)2D deficiency were compared to other patients, but patients with undetectable 1,25-(OH)2D had significantly elevated serum phosphate levels. Furthermore, patients with undetectable 1,25-(OH)2D levels were characterized by advanced clinical HIV infection, low CD4+ lymphocyte counts, and high serum levels of tumor necrosis factor-α (TNFα). We conclude that inadequate 1α-hydroxylation of 25-hydroxyvitamin D seems to be the most likely cause of 1,25-(OH)2D deficiency in HIV-infected patients, possibly induced by an inhibitory effect of TNFα. The low 1,25-(OH)2D and high TNFα levels observed may impair the immune response in HIV-infected patients both independently and in combination and may represent an important feature of the pathogenesis of HIV-related immunodeficiency. Markedly depressed 1,25-(OH)2D serum levels are also present in certain other disorders characterized by immunological hyperactivity. Thus, the findings in the present study may not only represent a previously unrecognized immune-mediated mechanism for induction of 1,25-(OH)2D deficiency in human disease, but may also reflect the importance of adequate serum levels of 1,25-(OH)2D for satisfactory performance of the immune system in man.

Seasonal variations of serum 1,25-dihydroxyvitamin D3 and alkaline phosphatase in relation to the antler formation in the fallow deer (Dama dama L.)

1984 ◽  
Vol 107 (1) ◽  
pp. 141-144 ◽  
Author(s):  
B. Eiben ◽  
St. Scharla ◽  
K. Fischer ◽  
H. Schmidt-Gayk
Keyword(s):  
Alkaline Phosphatase ◽  
Seasonal Variation ◽  
Serum Alkaline Phosphatase ◽  
Serum Levels ◽  
Fallow Deer ◽  
Dama Dama ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D3 ◽  
25 Hydroxyvitamin D

Abstract. Serum 1,25-dihydroxyvitamin D3 and serum alkaline phosphatase increased several fold during the antler formation period in July. Both maxima were observed in the second half of the antler formation period, where the mineralization of the antler takes place. In contrast serum levels of calcium and 25-hydroxyvitamin D3 showed no alternation or seasonal variation.

scholarly journals A Comparison of Free and Total 25-hydroxyvitamin D Levels as Functional Indicators of Bone Health in Healthy Children

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A270-A270
Author(s):  
You Joung Heo ◽  
Yun Jeong Lee ◽  
Kyunghoon Lee ◽  
Jae Hyun Kim ◽  
Choong Ho Shin ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Health ◽  
Normal Weight ◽  
Healthy Children ◽  
Vitamin D Metabolites ◽  
Dihydroxyvitamin D3 ◽  
Bone Parameters ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D ◽  
24,25 Dihydroxyvitamin D3

Abstract Abstract Context: The “free hormone” hypothesis suggests that the free 25-hydroxyvitamin D (25OHDFree) level may usefully indicate bone health. Objective: To determine which vitamin D measure is optimally correlated with clinical and bone parameters in healthy children. Design and Participants: A cross-sectional study including 146 healthy children (71 boys, 9.5±1.9 years) at a tertiary medical center. Main Outcome Measures: We used a multiplex liquid chromatography-tandem mass spectrometry-based assay to simultaneously measure vitamin D metabolites. The 25OHDFree level was directly measured (m-25OHDFree) or calculated using genotype-constant or genotype-specific affinity coefficients of vitamin D-binding proteins (con-25OHDFree or spe-25OHDFree). Bone mineral content (BMC) and density (BMD) were assessed via dual-energy X-ray absorptiometry. Results: The concentrations of total 25OHD (25OHDTotal), the three forms of 25OHDFree, and 24,25-dihydroxyvitamin D3 correlated with parathyroid hormone levels (all p&lt;0.01). Serum 25OHDTotal and m-25OHDFree levels reflected age, puberty, season, body mass index (BMI), daylight hours, and vitamin D intake (all p&lt;0.05). The con-25OHDFree level better reflected puberty and daylight hours than did the spe-25OHDFree level (both p&lt;0.01). The association between the 25OHDTotal level and bone parameters varied according to the BMI (interaction p&lt;0.05). In 109 normal-weight children, the con-25OHDFree level correlated with BMC and BMD (both p&lt;0.05), but the 25OHDTotal and 24,25-dihydroxyvitamin D3 levels were associated with BMC (both p&lt;0.05). No association was found in overweight or obese children. Conclusions: In healthy children, total and free 25OHD levels comparably reflected lifestyle factors. In normal-weight children, the con-25OHDFree level reflected BMC and BMD, whereas the 25OHDTotal level was associated with BMC.

1α-Hydroxyvitamin D3 Treatment of Three Patients With 1,25-Dihydroxyvitamin D-Receptor-Defect Rickets and Alopecia

PEDIATRICS ◽  
1987 ◽  
Vol 80 (1) ◽  
pp. 97-101
Author(s):  
E. Takeda ◽  
Y. Kuroda ◽  
T. Saijo ◽  
E. Naito ◽  
H. Kobashi ◽  
...  
Keyword(s):  
Vitamin D ◽  
Calcium Lactate ◽  
Type Ii ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
25 Hydroxyvitamin D

Three patients with clinically different severities of vitamin D-dependent rickets, type II, with alopecia, which is 1,25-dihydroxyvitamin D-receptor-defect rickets and is particularly resistant to treatment with calciferol analogues, were treated with large doses of lα-hydroxyvitamin D3 (1α-(OH)D3) and 2 g of calcium lactate. Except for the alopecia, all of the abnormalities of patients 1 and 2 were reversed by treatment with 3 µg/kg/d of 1α-(OH)D3, and those of patient 3, who had the severest manifestations, were reversed by treatment with 6 µg/kg/d. The serum 24,25-dihydroxyvitamin D concentrations of the three patients were low before treatment and those of patients 1 and 2 increased during treatment. These findings suggest that in patients 1 and 2, 25-hydroxyvitamin D-24-hydroxylase was stimulated via a 1,25-dihydroxyvitamin D-receptor-mediated system by treatment with 1α-(OH)D3.

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