{"doi":"10.17615/61t5-0v47","title":"In vitro synthesis of 1 alpha,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol by isolated calvarial cells.","abstract":"The question of whether the skeleton metabolizes 25-hydroxycholecalciferol [25(OH)D3] to more-polar products was studied. Calvarial cells were dispersed from 16-day old chicken embryos by using collagenase and then grown in culture in serum-free medium. Confluent cell cultures were incubated with 7 nM 25(OH)[3H]D3 for 2 hr, and the vitamin D metabolites were then extracted. At least four polar metabolites were produced. Based on separation by Sephadex LH-20 chromatography followed by high-pressure liquid chromatography, two of these metabolites were identified as 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25(OH)2D3]. These metabolites were also produced by cultured kidney cells but not by liver, heart muscle, or skin cells isolated from the same embryos. The specific activities of the calvarial 1- and 24-hydroxylases were similar in magnitude to those in isolated kidney cells. The specific activity of the calvarial 25(OH)D3:1-hydroxylase was inhibited by an 8-hr preincubation with 1,25(OH)2D3, whereas the 24-hydroxylase was enhanced. It is concluded that (i) vitamin D metabolism by isolated cells is organ-specific, (ii) calvarial cells produce active metabolites of vitamin D in significant amounts, (iii) vitamin D metabolism by calvarial cells is regulated by 1,25(OH)2D3, and (iv) locally produced, active metabolites could act locally, thereby adding a new dimension to the regulation of mineral metabolism by vitamin D metabolites.","journal":"UNC Libraries","year":2020,"id":117399,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9438,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":547783,"name":"G. A. Howard","orcid":null,"position":1,"is_corresponding":false},{"id":547784,"name":"D. J. Baylink","orcid":null,"position":2,"is_corresponding":false},{"id":195286,"name":"J. E. Puzas","orcid":null,"position":3,"is_corresponding":false},{"id":524304,"name":"T. K. Gray","orcid":null,"position":4,"is_corresponding":false},{"id":547785,"name":"M. D. Forte","orcid":null,"position":5,"is_corresponding":false},{"id":547786,"name":"R. T. Turner","orcid":null,"position":6,"is_corresponding":false},{"id":547782,"name":"G. E. Lester","orcid":null,"position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:13:51.309289Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}