A Defect in the Metabolism of Aromatic Amino Acids in Premature Infants: The Role of Vitamin C

A Defect in the Metabolism of Tyrosine and Phenylalanine in Premature Infants. I. Identification and Assay of Intermediary Products 12

“…7 The possibility that human milk contained accessory factors capable of ameliorating the metabolic anomaly was excluded by experiments in vitamin C-deficient guinea pigs fed unboiled human milk (17) of excretion was apparently not solely a function of the amount of amino acid administered. These differences in response of individual infants probably depended on the degree of vitamin C saturation of the tissues (18). The fact that the urinary output of hydroxyphenyl compounds reached equally high levels in the feeding observations with phenylalanine as with tyrosine suggests that the normal growing human organism can oxidize the phenyl ring of phenylalanine to p-hydroxyphenyl derivatives, a conclusion already shown for animals by feeding (19) and liver perfusion (20) experiments.…”

Distribution of Ascorbic Acid Between Cells and Serum of Human Blood 1

“…Transfers from serum to cells appeared to be associated with some metabolic activity of the cells, since they took place at 37°C., but not at 70 C. (14), from studies on infants have concluded that the metabolism of aromatic amino acids depends upon the quantities of ascorbic acid stored in the body. In the example just discussed, the influence of serum upon cell function was related to concentrations of ascorbic acid in the former; the effect of incubated serum upon cell volumes cannot be correlated with any known factor.…”

The Acid-Base Balance of Premature Infants 1

“…While this study was in progress, work was published on the presence of abnormal products of the metabolism of tyrosine and phenylalanine in the urine of premature infants who had received no ascorbic acid (18,19). All the patients except A53370, A53371, and A53019 had been given 25 mgm.…”