Human Biochemical Development

Gaull, Gerald E.; Hommes, F.A.; Roux, J

doi:10.1007/978-1-4684-0814-0_2

Cited by 6 publications

(2 citation statements)

References 383 publications

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“…The greater proportion of plasma TEAA as threonine is readily explained by immaturity of serine dehydratase activity as postulated by Rigo & Santerre (18). (19)(20). Elevated plasma absolute and relative concentrations of tyro-sine occur frequently in preterm infants and are associated with increased urinary excretion of p-hydroxyphenylpyruvate suggesting that inactivity or immaturity of p-hydroxyphenylpyruvic acid oxidase is the explanation As a result of these and perhaps other immature metabolic pathways, the plasma of the preterm infant is deranged relative to that of the term infant and that of the new tissue.…”

Section: Plasma Amino Acid Profiles Of Lb W Infantsmentioning

confidence: 99%

FOOD AND METABOLISM IN INFANCY The relationships of plasma amino acids as an indicator of the adequacy of protein intake

1982

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Heird, W. C., Dell, R. B. and Winters, R. W. (Department of Pediatrics and Institute of Human Nutrition, Columbia University College of Physicians & Surgeons, New York). Food and metabolism in infancy. Acta Paediatr Scand, Suppl. 299: 24, 1982.—Published plasma amino acid data from normally‐growing term and preterm infants fed varying quantities of protein as well as proteins of varying quality were examined in an effort to assess the efficacy of these data as indicators of the adequacy and/or inadequacy of protein intake. Although the absolute plasma concentrations of most amino acids vary considerably, all sets of data from term infants, with exception of those from infants fed inadequate protein or inordinately large quantities of protein, when expressed as the ratio of TEAA/TAA and ind. EAA/TEAA, are remarkably similar. Despite variations in absolute plasma amino acid concentrations of as much as 60 %, for example, fasting and postprandial TEAA/TAA and ind. EAA/TEAA ratios are similar. The plasma TEAA/TAA ratio of infants fed a low protein intake (1.1 g/kgd) is low but this ratio is similar in plasma of infants fed either 3.0‐3.5 g/kgd or 9 g/kgd. Ind. EAA/TEAA ratios, on the other hand, are the same in plasma of infants fed either 1.1 or 3.0‐3.5 g/k ‐ d but some are dramatically higher in plasma of infants fed a protein intake of 9.0 g/kgd. Although ind. EAA/TEAA ratios vary somewhat as a function of the quality of protein intake, this variation is not nearly as great as that of the intake ratios. Finally, the relatively constant plasma ratios of TEAA/TAA and ind. EAA/TEAA are remarkably similar to those of the tissue deposited during normal growth. These observations support the hypothesis that the various enteric, hepatic and other mechanisms which determine the amino acid composition of plasma have as their target these relationships among various amino acids rather than absolute plasma concentrations of the various amino acids. If so, it follows that maintenance of these relationships may be an important factor for optimal protein synthesis. If these hypotheses prove to be correct, an appropriate criteria for efficacy of alternative feeding regimens chosen for the infant who is not or cannot be breast fed is whether or not this regimen overwhelms the mechanisms responsible for maintaining these apparent relationships among the amino acids in plasma.

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Section: Plasma Amino Acid Profiles Of Lb W Infantsmentioning

confidence: 99%

FOOD AND METABOLISM IN INFANCY The relationships of plasma amino acids as an indicator of the adequacy of protein intake

1982

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“…The enzyme has an obligatory requirement for a reductant, e.g., ascorbic acid, which may keep enzyme-bound iron in the Fe2+ state necessary for activity [20], Delayed postnatal induction of the preced ing enzyme in the pathway, tyrosine trans aminase, with low activity in preterm neo nates has also been postulated [3]. In con trast, deficiency of phenylalanine hydroxy lase activity is very unlikely [21,22].…”

Section: Discussionmentioning

confidence: 99%

Metabolism of Intravenous Phenylalanine by Babies Born before 33 Weeks of Gestation

Walker

Mills²

1990

Neonatology

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Random urine samples collected weekly from 22 infants of 25–32 weeks of gestation were analyzed by capillary gas chromatography-mass spectrometry to define the normal organic acid profile. Increased excretion of phenolic acid derivatives of phenylalanine and tyrosine was found in 21 samples from 13 babies during established parenteral nutrition. Compared with 53 samples collected during milk feeding, phenyllactic acid, 4-hydroxy-3-methoxyphenyllactic acid, and N-acetyltyrosine were excreted significantly more often and 4-hydroxyphenyllactic and 4-hydroxyphenylpyruvic acids at significantly higher concentrations. The mean daily intake of phenylalanine (197 mg/kg) was significantly higher and that of tyrosine (22 mg/kg) significantly lower during parenteral nutrition. Three cyclohexanediol isomers were identified which might have derived from phenylalanine or one of its metabolites.

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