To examine for a possible local action of vitamin D on skin, its histology DNA content, melanogenetic response to UV and proliferative activity (incorporation of 3H thymidine into DNA) were studied on vitamin D deficient and vitamin D fed rats. The skin thickness DNA content and melanogenetic response to UV (assessed as the activity of skin tyrosinase) were greater in vitamin D fed than in vitamin deficient rats. In keratinocyte cell cultures vitamin D (10-9 M-10-12 M) increased DNA synthesis in suprabasal cells whereas it had no effect on DNA synthesis in basal cells. The influence of vitamin D on skin thickness and melanogenetic response to UV could provide an effective feed-back control for protection against UV penetration and vitamin D intoxication.

Animals↗

PubMedDate not supplied

[Vitamin D metabolism in rat calvarium in vitro (author's transl)].

The in vitro formation of 24, 25-(OH) 2D3 during incubation of rat calvarium with 25-(OH) D3 could be demonstrated. The in vitro synthesis of 24, 25-(OH) 2D3 has been localized in the mitochondrial fraction of the calvarium tissue. It could be detected also in calvarium cells in culture, but results indicate that the ability to synthetize 24, 25-(OH) 2D3 may be specific of some cell types only. The in vitro formation of 24, 25-(OH) 2D3 was observed with calvarium from rat neonates as well as from younger fetal rats, yet, in this latter period the in vitro formation of 24, 25-(OH) 2D3 was not found at all days of pregnancy tested in our experimental conditions (17th to 21st day).

Animals↗

PubMedDate not supplied

[Therapeutic application of vitamin D, its derivatives and analogues (author's transl)].

The synthesis of vitamin D derivatives and analogues, more especially that of 25-hydroxyvitamin D, 1, 25-dihydroxyvitamin D et l alpha-hydroxyvitamin D has opened a new field of investigation in pediatric pharmacology. These substances allows to achieve replacement therapy in pathological states characterized by a decreased formation of 25-hydroxyvitamin D (hepato-cellular diseases) or, 1, 25-dihydroxyvitamin D (renal diseases). Moreover, their utilisation at pharmacological doses has improved the therapeutic results in a number of pediatric diseases. In the present report are more especially summarized the results obtained with these three derivatives in patients with secondary hyperparathyroidism, hypo or pseudo-hypoparathyroidism.

Calcifediol↗