No abstract

No abstract

Ascorbic acid deficiency in guinea pigs fed a vitamin D-replete diet caused a moderate reduction of Ca level in serum and bone; 25-hydroxy-cholecalciferol or 25-hydroxyergocalciferol (25-OHD) serum concentration tended to decline; renal 25-hydroxycholecalciferol-1-hydroxylase (1-OHase) activity decreased 50%; and 25-hydroxycholecalciferol-24-hydroxylase activity increased 1.6-fold. Chromatin 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] receptor concentration in the intestinal mucosa decreased 20-30%, and the percentage of occupied receptors decreased from 12-15% to 6-8%. Receptor affinity for 1,25-(OH)2D3 did not change (Kd = 0.24-0.26 nmol/L, Kd2 = 0.06-0.10 nmol/L), but the cooperativity coefficient decreased from 1.7 to 1.4. Vitamin C deficiency potentiated effects of vitamin D deprivation and impaired a restorative action of vitamin D. It was accompanied by a marked delay in the elevation of 25-OHD concentration in serum as well as decreased 1-OHase activity in kidneys and a lower concentration of occupied 1,25-(OH)2D3 receptors in the intestinal mucosa. The data demonstrate a critical role for ascorbic acid in vitamin D metabolism and binding.

No abstract

A method for plasma riboflavin determination by riboflavin-binding apoprotein titration has been proposed for vitamin B₂ status evaluation. The method is based on the formation of riboflavin-apoprotein complex accompanied by full loss of fluorescence peculiar to free riboflavin. The data obtained have demonstrated a correlation with indicators of the vitamin B₂ status such as urinary excretion, erythrocyte content, and stimulation of the glutathione reductase activity by flavin adenine dinucleotide. Levels > 6 ng/ml blood plasma may be considered to be a criterion for normal vitamin B₂ supply.

The article presents the results of the genome-wide bioinformatic analysis of the vitamin D receptor interactions with the human genome DNA. Using a biological system assay, biological roles of proteins were analyzed that are specifically associated with the impact of VDR receptor. Systematization of the biological roles of vitamin D opens broad and previously unexplored perspectives for pediatric applications of vitamin D preparations for the prevention and treatment of a wide range of diseases starting from the fetal stage and early childhood.

No abstract

No abstract