An improved competitive protein binding assay for 1,25-dihydroxyvitamin D

Mallon, John; Hamilton, James G.; Nauss-Karol, Cheryl; Karol, R.; Ashley, Constance J.; Matuszewski, Diana S.; Tratnyek, Carol A.; Bryce, Graeme F.; Miller, O. Neal

doi:10.1016/0003-9861(80)90512-3

Cited by 57 publications

(7 citation statements)

References 8 publications

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“…The calcium content of the plasma was determined by atomic absorption spectrophotometry " by the method of Harris and Popat (1954) and calcium by the method of Slavin (1964). The vitamin D assays were conducted according to the procedure of Mallon et al (1980). The data were subjected to the analysis of variance and the standard errors of the mean determined.…”

Section: Methodsmentioning

confidence: 99%

Plasma Calcium, Phosphorus, 25-Dihydroxyvitamin D3, and 1-25-Dihydroxyvitamin D3 of Hens with Fatty Liver Syndrome

1985

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Plasma was obtained from normal laying hens, 30 weeks of age, and from laying hens, 60 weeks of age, with fatty liver syndrome (FLS). The 60-week-old hens were divided into two groups based on whether they were laying or nonlaying. Plasma phosphorus and calcium was significantly higher for hens with FLS. The younger hens had significantly lower 25-dihydroxyvitamin D3 (25-OH-D3) plasma levels than the older hens. The older hens that were laying had significantly lower 25-OH-D3 plasma levels than the nonlaying hens. Old nonlaying hens with FLS had lower 1, 25-OH-D3 than young hens or old laying hens with FLS; however, the levels were not different for the two groups of laying hens.

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Section: Methodsmentioning

confidence: 99%

Plasma Calcium, Phosphorus, 25-Dihydroxyvitamin D3, and 1-25-Dihydroxyvitamin D3 of Hens with Fatty Liver Syndrome

1985

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“…A 100-mg oral dose of 47Ca was given at 8:00 A M after an overnight fast. Blood samples were then drawn and serum calcium, inorganic phosphatase, alkaline phosphatase, and creatinine concentrations and 24-hour urinary calcium and creatinine levels were determined by an automated analyzer (Technicon Instruments, Tarrytown, NY (21). These assays were performed at 3-month intervals throughout the study.…”

Section: Methodsmentioning

confidence: 99%

Effect of oral 1,25‐dihydroxyvitamin D and calcium on glucocorticoid‐induced osteopenia in patients with rheumatic diseases

Dykman

Haralson

Gluck

et al. 1984

Arthritis & Rheumatism

150

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Twenty-three rheumatic disease patients with glucocorticoid-induced osteopenia (defined by measurement of forearm bone mass) completed an 18-month double-blind, randomized study to assess the effect of oral calcium and 1,25-dihydroxyvitamin D ( 1,25-OH2D) or calcium and placebo on bone and mineral metabolism. Intestinal 47Ca absorption was increased (P < 0.05) and serum parathyroid hormone levels were suppressed (P < 0.01) by 1,25-OH2D (mean dose 0.4 pgl day); however, no significant gain in forearm bone mass occurred, and bone fractures were frequent in both groups. In the 1,25-OH2D group, histomorphometric analysis of iliac crest biopsy specimens demonstrated a decrease in osteoclasts/mm2 of trabecular bone (P < 0.05) and parameters of osteoblastic activity (P < 0.05), indicating that 1,25-OH2D reduced both bone resorption and formation. We conclude that 1,25-OH2D should not be used for treatment of glucocorticoidinduced osteopenia. Since patients receiving calcium and placebo did not exhibit a loss of forearm bone mass, elemental calcium supplementation of 500 mg daily might be useful to maintain skeletal mass in patients receiving long-term glucocorticord therapy. Submitted for publication March 27, 1984; accepted in revised form July I I , 1984. Oral administration of glucocorticords in humans results in severe osteopenia caused by several mechanisms (1-3). Histologic studies of bone in humans receiving glucocorticoids demonstrate decreased bone formation (4-6) and increased numbers of osteoclasts and osteoclast-resorbing surfaces (5-7). The decrease in formation rate probably represents a direct effect of glucocorticoids on osteoblasts. Specifically, glucocorticoids decrease the recruitment of progenitor cells to osteoblasts and the synthesis of collagen and noncollagen protein by preexisting osteoblasts (8,9).The mechanism by which glucocorticoids increase bone resorption is more controversial. In vitro, glucocorticoids inhibit osteoclast activity (3, lo). However, in vivo, glucocorticoids greatly decrease intestinal calcium absorption (2,11,12) and may stimulate parathyroid hormone (PTH), thus providing an indirect stimulus to osteoclastic activity (6,13

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“…The most significant improvement offered by this new assay is the elimination of HPLC as the final purification step before assay. There are three previously described assays in which 1,25-(OH) 2 D was not purified by HPLC before assay (17,23,29). The first of these assays was also the first 1,25-(OH) 2 D assay developed (17).…”

Section: Jce and M • 1984mentioning

confidence: 99%

A Microassay for 1,25-Dihydroxyvitamin D Not requiring High Performance Liquid Chromatography: Application to Clinical Studies*

Reinhardt

Horst

Orf

et al. 1984

The Journal of Clinical Endocrinology & Metabolism

800

190

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This report describes a microassay for 1,25-dihydroxyvitamin D [1,25-(OH)2D] in plasma which does not require high performance liquid chromatography. The assay involves rapid extraction and preliminary purification on a C-18 Sep-Pak cartridge, followed by final purification on a silica Sep-Pak using hexane-isopropanol. Quantitation of 1,25-(OH)2D is achieved using a nonequilibrium assay employing 1,25-(OH)2D receptor from calf thymus. The method is sensitive to 1.5 pg/tube, with B50 occurring at 9 pg/tube and a useful assay range of 1.5-40 pg/tube. The intra- and interassay coefficients of variation are 6.5% and 11.5%, respectively, and the method is linear over a wide range of sample dilutions. In addition, this assay measures both 1,25-(OH)2D2 and 1,25-(OH)2D3 with equal affinity. The importance of using an assay with equal affinity for 1,25-(OH)2D2 and 1,25-(OH)2D3 is demonstrated by the findings that 25-hydroxyvitamin D2 (250HD2) constituted 38.9% of the total 25-OHD found in clinical samples (12.6 +/- 0.7 ng/ml 25-OHD2 vs. 20.1 +/- 0.5 ng/ml 25-OHD3; n = 807). Results of this new assay have been compared to those of the assay of Horst et al. (21), which employs Sephadex LH-20 and high performance liquid chromatography sample purification. The correlation coefficient was r2 = 0.96, and the slope was 1.05. Using this new assay, plasma 1,25-(OH)2D concentrations were as follows: normal adults, 37.4 +/- 2.2 pg/ml (n = 22); chronic renal failure, 10.6 +/- 1.5 pg/ml (n = 7); anephrics, undetectable (n = 10); infant cord blood, 22.9 +/- 4.4 pg/ml (n = 7); and hyperparathyroidism, 68.9 +/- 5.0 pg/ml (n = 13). This assay should be particularly useful in pediatric or other studies in which sample size is limited.

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An improved competitive protein binding assay for 1,25-dihydroxyvitamin D

Cited by 57 publications

References 8 publications

Plasma Calcium, Phosphorus, 25-Dihydroxyvitamin D3, and 1-25-Dihydroxyvitamin D3 of Hens with Fatty Liver Syndrome

Plasma Calcium, Phosphorus, 25-Dihydroxyvitamin D3, and 1-25-Dihydroxyvitamin D3 of Hens with Fatty Liver Syndrome

Effect of oral 1,25‐dihydroxyvitamin D and calcium on glucocorticoid‐induced osteopenia in patients with rheumatic diseases

A Microassay for 1,25-Dihydroxyvitamin D Not requiring High Performance Liquid Chromatography: Application to Clinical Studies*

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