Influence of vitamin C and magnesium on calcium, magnesium and copper contents of guinea pig tissues.

The effects of a high dose of ascorbic acid superimposed on a low magnesium diet were studied for the first time. Young male guinea pigs were fed for six weeks two diets containing 3000 or 600 ppm magnesium: half in each group was supplemented with a daily oral dose of either 3 mg or 100 mg ascorbic acid per 100 g body weight. No treatment effects were found in serum copper and ceruloplasmin, spleen copper, bone calcium, kidney magnesium, and brain calcium and magnesium contents. Both bone copper and brain ascorbic acid contents of the group fed the normal ascorbic acid/low magnesium diet were lower (p less than 0.01) than the combined means of the other three groups; the high ascorbic acid/low magnesium treatment resulted in normalization of bone copper and brain ascorbic acid levels. Irrespective of ascorbic acid level, the low magnesium diet decreased the bone magnesium and increased the kidney calcium contents (p less than 0.01); this effect on kidney was nearly doubled by the high ascorbic acid intake (p less than 0.01). The results indicated that the main effects were due to the magnesium deficit.

Influence of vitamin C restriction on guinea pig adrenal calcium and plasma corticosteroids.

Some aspects of adrenocortical function were investigated in young male guinea pigs fed an ascorbic acid (AsA)-deficient diet for 7 days, followed by 0.1 mg AsA/100 g body weight/day for 4 days; pair-fed guinea pigs served as controls. Ninety minutes prior to killine, all guinea pigs received either an adrenocorticotropic hormone (ACTH) or saline injection, and 30 minutes prior to killing, all were injected with 20 muCi 45Ca/100 g body weight intraperitoneally. AsA restriction alone caused an 89% reduction in adrenal AsA concentration, but growth rate, adrenal weight and plasma ACTH were not different from those of pair-fed controls. Adrenal radiocalcium uptake, adrenal calcium content and plasma corticosteroids were similar in saline-treated guinea pigs restricted in AsA and the ACTH-treated controls, all of which were significantly higher than the values observed in saline-injected controls. Similar responses of the ACTH-treated controls and the saline-treated mildly deficient guinea pigs indicated that, at the adrenal AsA levels achieved (4.45 to 7.02 mg/100 g tissue), adrenal calcium and plasma corticosteroids increased significantly without the mediation of ACTH.

Proton-induced x-ray emission analysis of single human hair roots.

Collimated beams of 3.75 million electron volt protons were used to examine a 2-millimeter length of the root end of human hair; the concentrations of some hair root elements were correlated with the results of standard clinical assays of blood samples. The technique should be useful for the analysis of micro amounts of biological tissue.