Augusta B. McCoord

The carotinoids and vitamin A of the blood.

Summary The observations recorded in this paper clearly indicate the effect of the intake of carotene and xanthophyll upon the carotinoid content of the plasma. Relatively large amounts of those substances may pass through the placenta to the fetus. Vitamin A probably also passes through the placenta, but the fetus may also be able to form vitamin A from carotene. Normal infants and older persons readily absorb carotene from the diet or from solutions of carotene in oil, but the rate of absorption is slower than the rate of absorption of vitamin A. The low carotinoid content of the diet in early infancy and in the winter months explains the lower concentration of carotene and xanthophyll in the first six months of life and in the winter months. The mean vitamin A concentration of the plasma in normal persons reaches a constant level soon after birth and is not affected by season. The variations between single determinations are great. Infection causes a prompt and considerable fall in the concentration of carotene, xanthophyll and vitamin A in the plasma. This fall is due, in part, to low intake during infection, but is also due, in part, to fever. A few days after the temperature becomes normal, the vitamin A content of the plasma may rise considerably above normal. Xanthosis cutis in normal persons, in diabetics, and in hypothyroidism is associated with an increase of carotene in the plasma, less often of xanthophyll. In severe untreated diabetes the tissues may not be able to metabolize carotene rapidly. In nephrosis and in severe chronic nephritis hypercarotinemia may occur without xanthosis cutis. In Brights disease the level of plasma vitamin A may be greatly elevated, probably because the liver fails to store it. In hypothyroidism the carotinoids of the plasma may be elevated and the vitamin A may be low. Successful treatment with thyroid substance corrects the anomaly. In celiac disease the carotinoids and vitamin A are not readily absorbed.

Vitamin A absorption in celiac disease

Summary Patients with celiac disease are unable to absorb vitamin A normally and when given a large amount of vitamin A by mouth do not show an increase in the blood vitamin A equal to that of a group of children with other diseases. This inability of the patient with celiac disease to absorb vitamin Ais usually associated with a flat sugar tolerance curve, increased per cent of fat in stools, and low carotenoid pigments in the blood. This inability to absorb vitamin A normally, although characteristic ofceliac disease, does occur in other diseases and is, therefore, not pathognomonic of celiac disease.

Relation of age to radiomagnesium exchange in bone.

Summary In the rat, the exchange of Mg28 in cortical bone occurs much more rapidly in young animals than in old. The stable magnesium content of bone increases with age, varies inversely with bone water content. A method for separating Mg from Ca and P by cation exchange chromatography is described.

The relationship between biophotometer tests and the vitamin A content of the blood of children

Summary No correlation was found between biophotometer readings and vitamin A content of the blood of ninety-eight untrained subjects. The percentage of subnormal readings approximated that observed by Jeans when our cases were regrouped by his standards. The decrease in number of subnormal readings found in our series of trained subjects indicates that the training factor is important. A single reading on the biophotometer is of no value in estimating vitamin A deficiency. The reading obtained by frequent testing with the biophotometer did not correlate with the blood vitamin A values of our subjects.