Editorial: 24, 25-Dihydroxyvitamin D—Active Metabolite or Inactive Catabolite?

Measurement of mammalian 25 - hydroxyvitamin D 3 24 R - and la - hydroxylase ( 1 , 25 - dihydroxyvitamin D 3 / 24 , 25 - dihydroxyvitamin D / kidney / calcium ) YOKO TANAKA AND

An in vitro assay of mammalian 25-hydroxyvitamin D3 laand 24R-hydroxylases in kidney has been developed. It had been suggested that 25-hydroxyvitamin D binding protein present in mammalian blood and tissues inhibits the enzyme activities in cell-free preparations by binding the substrate 25-hydroxyvitamin D3 more strongly than the hydroxylases bind it. This inhibitory effect is overcome by the ...

Regulation of rat yolk sac 25-hydroxy- and 1,25-dihydroxyvitamin D3 24-hydroxylase activities.

The yolk sac of the pregnant rat which functions as a true placenta is a target organ for vitamin D. This tissue can hydroxylate in position 24 both 25-hydroxy- and 1,25-dihydroxyvitamin D3 (25-OHD3 and 1,25-(OH)2D3). The present report describes an in vitro model for the study of 1,25-(OH)2D3 action on the further metabolism of 25-OH[3H]D3 and 1,25-(OH)2[3H]D3 by yolk sac. The tissue explants ...

23 24 25

Cécile FAUVELOT, Francesca BERTOZZI, Federica COSTANTINI, Laura AIROLDI, Marco 1 ABBIATI 2 3 Lower genetic diversity in the limpet Patella caerulea on urban coastal structures compared to 4 natural rocky habitats 5 6 7 1 Centro Interdipartimentale di Ricerca per le Scienze Ambientali and Dipartimento di Biologia 8 Evoluzionistica Sperimentale, University of Bologna, Via S. Alberto 163, I – 4810...

The 24-hydroxylation of 1,25-dihydroxyvitamin D3.

The production of 1,24,25-trihydroxyvitamin D3 in vivo in vitamin D-deficient rats has been demonstrated from either 25-hydroxyvitamin D3 or 1,25-dihydroxyvitamin D3. The stereochemical configuration of the hydroxyl on the 24 position of 1,24,25-trihydroxyvitamin D3 has also been unambiguously established to be R. Nephrectomy failed to eliminate the conversion of 1,25-dihydroxyvitamin D3 to the...

Lecture 24 — November 25