Leonora S. Galante

Effect of prolactin on vitamin D metabolism

The effect of ovine prolactin on the renal 25-hydroxycholecalciferol-1-hydroxylase was studied in the chick. Prolactin was found to increase the activity of this enzyme in both long-term and short-term experiments. In the long term, 7 days treatment with prolactin caused a marked stimulation of the 1-hydroxylase activity, however this effect was only seen when the enzyme was assayed 2-3 hours after the final injection of prolactin. A single subcutaneous injection of prolactin was also effective in increasing the 1-hydroxylase activity, this effect was maximal at one hour and had largely disappeared 3 hours after prolactin administration.

CALCITONIN IN BREAST AND LUNG CANCER

Immunoreactive calcitonin was found in extracts of seven out of eight consecutive breast carcinomas and four selected lung carcinomas, but not in extracts of benign breast lesions or normal tissues.

Separation of hydroxylated derivatives of vitamin D3 by high speed liquid chromatography (HSLC).

The recent upsurge of interest in the metabolism of vitamin D3 (cholecalciferol) has relied partly on the use of partition chromatography on Sephadex LH-20 as an analytical tool to separate metabolites [ 1 ] . This system is simple but it is relatively slow and resolution is poor. We present here a method for the separation of hydroxylated derivatives of vitamin D3 using high speed liquid chromatography. First, resolution is orders of magnitude greater: metabolites unresolved on Sephadex LH-20 are separated. Second, an analysis is complete in under 30 min. Third, fractions may also be collected for further studies, e.g. determination of radioactivity. Fourth, continuous monitoring of the column effluent by UV absorption is possible. Further, this technique allows co-chromatography of authentic synthetic compounds with experimentally produced radioactive metabolites to facilitate identification. Using this approach we have confirmed previously the identity of the major metabolite of 25-hydroxycholecalciferol(25-HCC) under conditions of calcium deprivation to be 1,25-dihydroxy-cholecalciferol(l,25-DHCC) by its co-elution with a synthetic sample [23.