VITAMINS

Circulating 25-0H-D and 1,25-(OH)_2-D were measured in a variety of diseases. In patients with primary hyperparathyroidism and pregnant women, serum 1,25-(OH)_2-D was elevated, while it was suppressed in patients with hyperthyroidism, chronic renal failure, hYPoparathyroidism, hypophosphatemic osteomalacia, Fanconi syndrome, renal tubular acidosis, tumor-induced osteomalacia, liver cirrhosis, hepatoma, and primary biliary cirrhosis. In patients with osteoporosis, and type II diabetes mellitus, serum 1,25-(OH)_2-D was slightly suppressed within the normal range. Circulating 1,25-(OH)_2-D scattered in the normal range in patients with sarcoidosis and calcitonin excess status. Thus, clinical data of circulating vitamin D metabolites measurement were presented and their evaluation was discussed.

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Metabolism of nicotinate moiety of dl-α-tocopherylnicotinate (Toc-nic) in rats was compared with that of free nicotinic acid. (1) When a nicotinic acidfree, tryptophan-limited diet containing 0.065% Toc-nic was fed to weanling rats for 14 days, they grew up as well as rats fed the tryptophan-limited diet containing 0.015% nicotinic acid and 0.05% dl-α-tocopherol. From the 15th day on the nicotinic acid-free, tryptophan-limited diet was fed to both groups of rats. As a result, body weight gains of rats previously fed the Toc-nic diet were superior to those of rats previously fed the nicotinic acid diet. Urinary excretion of niacin and N^1-methylnicotinamide was lower in the Toc-nic group than in the nicotinic acid group. These results mean that the retaining activity by body is higher in Toc-nic than in nicotinic acid. (2) Even when a 20% casein diet containing large amount of Toc-nic (0.5%) was fed to weanling rats, the body weight gains of rats were almost the same as those of rats fed the 20% casein diet and the 20% casein diet containing 0.11% nicotinic acid and 0.39% dl-a-tocopherol. The NAD levels of liver, kidney and blood in the group of Toc-nic were increased compared with those in the group of the 20% casein diet, but the increase in NAD level was lower in the Toc-nic group than in the nicotinic acid group. Urinary excretion of niacin, N^1-methylnicotinamide, N^1-methyl-2-pyridone-5-carboxamide and nicotinuric acid was increased by the feeding of Toc-nic-containing diet and nicotinic acid-containing diet, compared with those of the group of the 20% casein diet. The ratio of the increased amount of the Toc-nic group to the increased amount of nicotinic acid group in urinary excretion of niacin, N^1-methylnicotinamide, N^1-methyl-2-pyridone-5-carboxamide and nicotinuric acid were 1/8.6, 1/4.6, 1/3.1 and 1/16.1, respectively. These results indicate that the turnover rate of nicotinate moiety of Toc-nic is slower than that of free nicotinic acid.

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