The action of various vitamin D3 metabolites on calcium and phosphorus metabolism in chick embryo calvariae

Chick embryos from vitamin D-deficient hens given physiological doses of 1,25-dihydroxyvitamin D3 or 24,25-dihydroxyvitamin D3 or both become severely hypocalcemic, hyperphosphatemic and fail to hatch as compared to those derived from hens given 25-hydroxyvitamin D3 or 24,25-difluoro-25-hydroxyvitamin D3. Calvariae from the former contain less mineral and on incubation in vitro produce significantly lower calcium and higher phosphate concentration in the medium than do the calvariae derived from the embryos of hens supported on 25-hydroxyvitamin D3 or 24,24-difluoro-25-hydroxyvitamin D3.     

The action of various vitamin D3 metabolites on calcium and phosphorus metabolism in chick embryo calvariae

Summary Chick embryos from vitamin D-deficient hens given physiological doses of 1,25-dihydroxyvitamin D₃ or 24,25-dihydroxyvitamin D₃ or both become severely hypocalcemic, hyperphosphatemic and fail to hatch as compared to those derived from hens given 25-hydroxyvitamin D₃ or 24,25-difluoro-25-hydroxyvitamin D₃. Calvariae from the former contain less mineral and on incubation in vitro produce significantly lower calcium and higher phosphate concentration in the medium than do the calvariae derived from the embryos of hens supported on 25-hydroxyvitamin D₃ or 24,24-difluoro-25-hydroxyvitamin D₃.     

Vitamin D3 sulfoconjugate distribution and evolution in pregnant or lactating rats]

24 hrs after intravenous injection of vitamin D3 35S sulfoconjugate the radioactivity in kidney is about twice as much in pregnant Rats as in lactating Rats. It decreases from 24 to 48 hrs in pregnant but increases in lactating Rats kidneys. Hydrolysis of vitamin 3H D3 sulfate is detected in kidney and liver extracts, the ratio of free vitamin D3 on vitamin D3 sulfate is higher in pregnant than in lactating animals. Mammary glands of lactating Rats contain mainly the unchanged vitamin D3 sulfate which can be hydrolysed by new born suckling pups.     

Persistance of maternally derived3H-estradiol in fetal and neonatal rats

Summary Injection of³H-estradiol into pregnant rats resulted in fetal blood radioactivity 5 times higher than in maternal blood. Significant amounts of³H-estradiol were found in fetal blood 24 h later and in the offspring 5 days after birth.Supported by NIH Grant HD 08844.     

The effect of anesthetics on the basal secretion of immunoreactive growth hormone in rats]

The authors investigated basal levels of plasma immunoreactive growth-hormone in the rat (R-GH) after administration of 3 different anesthetic drugs: urethan, chloral hydrate and gamma-hdroxy-butyrate (GHB). Lowest R-GH concentrations (5 +/- 3 ng/ml) are observed after urethan; they are significantly higher (15 +/- 4 ng/ml) after chloral hydrate but this anesthetic also causes hyperglycemia (210 +/- 30 mg/100 ml). Normal blood glucose levels are observed under GHB narco-analgesia which elicits a clear-cut R-GH secretory episode (70 +/- 5 ng/ml); basal values (12 +/- 3 ng/ml) are maintained for several hours thereafter.     

Interaction of glucocorticosteroids with glucagon in the control of argininosuccinase activity in the fetal rat liver]

Exogenous glucagon, but not glucocorticosteroids cause a rise in argininosuccinase activity in the liver of 21.5 day old fetuses. When fetuses are deprived of glucocorticosteroids, glucagon is unable to promote the enzymic activity. This study indicates that glucocorticosteroids are required for the induction of the argininosuccinase activity by glucagon.     

Autoradiographic study of proliferative activity and cell migration in the adrenal cortex in fetal and neonatal rats]

On the 20th day of fetal life the cell proliferation is higher in the zona glomerulosa. The fate of marked cells in each cell compartment shows centripetal migration. Their displacement, from the 20th day of pregnancy up to five days post-partum, while at that time the adrenal growth is slowered down, suggests a real migration.