Linked Life Data

1084355

Source:http://linkedlifedata.com/resource/pubmed/id/1084355

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1976-8-23
pubmed:abstractText
A competitive protein binding assay for measurement of the plasma concentration of 1 alpha, 25-dihydroxyvitamin D3 [1alpha, 25-(OH)2D3] has been extended to include the immediate precursor of this hormone, 25-hydroxyvitamin D3 (25-OHD3). In addition, the assay system is capable of measuring the two metabolic products of ergocalciferol, namely. 25-hydroxyvitamin D2 (25-OHD2) and 1alpha, 25-dihydroxyvitamin D2 [1alpha, 25-(OH)2D2]. The target tissue assay system consists of a high affinity cytosol receptor protein that binds the vitamin D metabolites and a limited number of acceptor sites on the nuclear chromatin. By utilizing a series of chromatographic purification steps, a single plasma sample can be assayed for any of the four vitamin D metabolites either individually or combined. Therefore, the assay procedure allows for both the quantitative and qualitative assessment of the total active vitamin D level in a given plasma sample. To show that the binding assay was capable of measuring 1alpha, 25-(OH)2D2 as well as 1alpha, 25 (OH)2D3, two groups of rats were raised. One group, supplemented with vitamin D3, produced assayable material that represented 1alpha, 25-(OH)2D3. The other group, fed only vitamin D2 in the diet, yielded plasma containing only 1alpha, 25-(OH)2D2 as the hormonal form of the vitamin. The circulating concentrations of the two active sterols were nearly identical (15 ng/100 ml) in both groups, indicating that the competitive binding assay can be used to measure both hormonal forms in plasma. In a separate experiment, 1alpha, 25-(OH)2D2 was generated in an in vitro kidney homogenate system using 25-OHD2 as substrate. Comparison of this sterol with 1alpha, 25-(OH)2D3 in the assay system showed very similar binding curves; the D2 form was slightly less efficient (77%). Comparison of the respective 25-hydroxy forms (25-OHD2 vs. 25-OHD3) at concentrations 500-fold that of 1alpha, 25-(OH)2D3, again suggested that the binding of the D2 metabolite was slightly less efficient (71%). Finally, the assay was employed to measure the total active vitamin D metabolite pools in the plasma of normal subjects and patients with varying degrees of hypervitaminosis D. The normal plasma levels of 25-OHD and 1alpha, 25-(OH)2D measured in Tucson adults were 25-40 ng/ml and 2.1-4.5 ng/100 ml, respectively. Both sterols were predominately (greater than 90%) in the form of vitamin D3 metabolites in this environment. Typical cases of hypervitaminosis D exhibited approximately a 15-fold increase in the plasma 25-OHD concentration, and a dramatic changeover to virtually all metabolites existing in the form of D2 vitamins. In contrast, the circulating concentration of 1alpha, 25-(OH)2D was not substantially enhanced in vitamin D-intoxicated patients. We therefore conclude that hypervitaminosis D is not a result of abnormal plasma levels of 1alpha, 25-(OH)2D but may be cuased by an excessive circulating concentration of 25-OHD.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-1115441, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-1188357, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-163254, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-212227, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4319631, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4322260, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4323313, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4328344, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4332615, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4333399, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4336370, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4347618, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4350978, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4351347, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4355503, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4359168, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4360685, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4360686, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4364805, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4370023, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4370557, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4372106, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4621128, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4777332, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4812038, http://linkedlifedata.com/resource/pubmed/commentcorrection/1084355-4865739
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9738
pubmed:author
pubmed:issnType
Print
pubmed:volume
58
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
61-70
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Radioligand receptor assay for 25-hydroxyvitamin D2/D3 and 1 alpha, 25-dihydroxyvitamin D2/D3.
pubmed:publicationType
Journal Article