The formation of 1,25-dihydroxycholecalciferol from 25-hydroxycholecalciferol by chick kidney homogenates is inhibited by increasing concentrations of Ca(2+). The apparent K(m) for the hydroxylation reaction is 1x10(-7)m, significantly lower than that reported for isolated mitochondria. Separated cytoplasmic and particulate fractions are inactive, but on recombination activity is restored, poss...

Recently a number of studies have reported worldwide recrudescence of biochemical and clinical rickets, despite continuous revisions of the experts about the adequate intake of vitamin D for infants and children to maintain an adequate 25-hydroxyvitamin D status and assure the achievement of peak bone mass during the growth. The aim of this review is to illustrate the current opinions and contr...

The approximate association constants of the plasma vitamin D binding globulin (Gc-globulin) for 25-hydroxycholecalciferol (25(OH)D3) and the plasma 25(OH)D3 binding capacities were measured in samples from 123 patients with a variety of disorders. No gross differences in binding affinities were observed between different groups of patients and controls. Many patients, however, had moderately r...

Results The age average of the babies who were studied was 20,3± 1,5 months. 46,9 % of the babies were girls, 53,1 % were boys. At the beginning of the study 12,5 % of the babies’ serum 25(OH)D3 levels were deficient, 39,1 % of the babies’ were insufficient, 48,4 % of the babies’ were sufficient. The average of the babies’ vitamin D level was 29,8 ±10,8 ng/ml. At the end of study, 29,7 % of the...

In biomarker-disease association studies, the long-term average level of a biomarker is often considered the optimal measure of exposure. Long-term average levels may not be accurately measured from a single sample, however, because of systematic temporal variation. For example, serum 25-hydroxyvitamin D (25(OH)D) concentrations may fluctuate because of seasonal variation in sun exposure. Assoc...

BACKGROUND Although solid cohort studies confirmed a preventative role for the anti-oxidant vitamin D in allergic asthma, a limited number of studies focused on allergic rhinoconjunctivitis (ARC). Here, we aimed to determine 25-hydroxycholecalciferol levels in tear and serum in young allergic rhinoconjunctivitis patients as compared to their apparently healthy matched controls. METHODS In tot...

Low 25-hydroxyvitamin D (25(OH)D) concentrations are common among older adults and are associated with poorer physical performance and strength, but results from longitudinal studies have been inconsistent. The 25(OH)D threshold for physical performance and strength was determined, and both cross-sectional and longitudinal associations between 25(OH)D and physical performance and strength were ...

The objective was to assess the vitamin D status in healthy 12-month-old infants in relation to quantity and sources of dietary vitamin D, breastfeeding and seasons. Subjects were 76 12-month-old infants. Serum levels of 25-hydroxyvitamin D (25(OH)D) ≥ 50 nmol/L were considered indicative of vitamin D sufficiency and 25(OH)D < 27.5 nmol/L as being indicative of increased risk for rickets. Addit...

The majority of the vitamin D in our body is produced by cutaneous synthesis in response to sunlight. As more and more people live in cities and spend the bulk of their time indoors, it can be difficult to get sufficient sun exposure for adequate cutaneous production of vitamin D. Therefore, vitamin D insufficiency has become a very common health problem worldwide. The Korea National Health and...