The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Comparison of effects of 1 alpha-hydroxy-vitamin D3 and 1,25-dihydroxy-vitamin D3 in man.

The effects of short-term treatment with 1,25-dihydroxy-vitamin D3 [1,25(0H)2D3] or 1 alpha-hydroxy-vitamin D3 [1 alpha(OH)D3] on intestinal absorption of 47Ca were compared in 41 experiments in normals and 72 experiments in patients with chronic renal failure. 11 patients were studied a second time after treatment for 2-5 mo. Doses varied from 0.14 to 5.4 mug/day to establish dose-response relationships. Urinary calcium was monitored in normal subjects, nine of whom received a constant calcium intake on a metabolic unit. There was an increase in intestinal absorption of 47Ca and urinary calcium in normals receiving 1,25 (OH)2D3, 0.14 mug/day or greater, and 0.28 mug/day or greater augmented intestinal absorption of 47Ca in chronic renal failure. In contrast, 2.6 mug/day of 1 alpha (OH) D3 was required to increase intestinal absorption of 47Ca in both groups. The increase in urinary calcium to maximal levels was delayed during treatment with 1 alpha (OH) D3, 5-10 days vs. 2-5 days with 1,25 (OH)2D3. Moreover, half times for urinary calcium to decrease to pretreatment levels after stopping treatment were greater after 1 alpha-(OH) D3 (1.5-2.7 days) than 1,25(OH)2D3 (1.1-2.0 days). With long-term administration there was a progressive increase in intestinal absorption of 47Ca in the patients receiving 1 alpha (OH)D3; this was not observed with 1,25(OH)2D3. The pharmacologic differences between 1 alpha(OH) D3 and 1,25(OH)2D3 may be explained by the requirement for 25-hydroxylation of 1alpha(OH) D3 before biologic effects occur; at low doses (less than 1 mug/day), 1 alpha(OH) D3 competes with vitamin D3 for 25-hydroxylation. With prolonged treatment or larger doses (greater than 2 mug/day),, 1alpha(OH) D3 could accumulate and then be hydroxylated resulting in production of higher levels of 1,25(OH)2D3.[1]


  1. Comparison of effects of 1 alpha-hydroxy-vitamin D3 and 1,25-dihydroxy-vitamin D3 in man. Brickman, A.S., Coburn, J.W., Friedman, G.R., Okamura, W.H., Massry, S.G., Norman, A.W. J. Clin. Invest. (1976) [Pubmed]
WikiGenes - Universities