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ABSTRACT: Two infants with disorders of propionate metabolism were studied at 7 months of age to determine optimum levels of intake of protein and calories to meet the requirements for essential amino acid for growth in infancy, and at the same time minimize the accumulation of toxic intermediates. An effect of alanine was found that permitted growth at otherwise limiting levels of protein intake. This was not simply an effect of nonessential nitrogen as neither glycine nor glutamic acid could substitute for alanine in this protein-sparing effect. This appears to represent further evidence of the relationship between alanine and the branched-chain amino acids and of the importance of the alanine-glucose cycle in human physiology.

• An 11-year-old girl with keratitis and plantar keratosis had tyrosinemia. The concentration of tyrosine in the plasma was 16.5 mg/dL. Dietary intake of phenylalanine and tyrosine was systematically varied, and the plasma concentrations of tyrosine and nitrogen balance were studied. It was necessary to achieve a total intake of phenylalanine and tyrosine less than 100 mg/kg/day to obtain plasma concentrations of tyrosine of less than 10 mg/dL. After dietary therapy was started, the keratitis resolved promptly, and the patient remained asymptomatic during a period of 16 months in which the mean plasma concentration of tyrosine was 11.1 mg/dL. The dietary management of a child at this age presents a different problem from that of a young infant. It can be successfully pursued at home, as well as in the carefully regulated environment of a clinical research center.(Am J Dis Child 1983;137:995-1000).

To evaluate the potential role of taurine deficiency in the pathogenesis of parenteral nutrition-induced cholestasis, 20 premature (<34 weeks AGA) infants were randomized to receive parenteral nutrition with and without taurine (10.8 mg/kg/day) during the first 10 days of life. Birth weight, gestational age, and protein and caloric intake were similar in both groups. Plasma taurine levels and hepatic function were assessed before the study began (3 ± 1 days of age), at 5 ± 1 days of age, and at 9 ± 1 days of age. Although plasma taurine levels were significantly greater at 5 ± 1 and 9 ± 1 days of age (p = 0.009) in the group receiving supplementation, no differential effect on hepatocellular function could be detected during this short period of time. A decrease in plasma ammonia (p = 0.001), alanine aminotransferase (ALT) (p = 0.036), γ-glutamyltranspeptidase (GGTP) (p = 0.05), 5-nucleotidase (5'N) (p = 0.001), and bile salt concentrations was noted in both groups, indicating the rapid maturation of hepatic function even in the presence of parenteral nutrition during the first 10 days of life.