Document Detail

A comparison of the estimates of whole-body protein turnover in parenterally fed neonates obtained using three different end products.
MedLine Citation:
PMID:  2505915     Owner:  NLM     Status:  MEDLINE    
Protein turnover rates in neonates have been calculated largely by measuring urinary [15N]urea enrichment following administration of [15N]glycine. Although ammonia has been increasingly recognized as an end product of nitrogen metabolism, in neonates it yields a different estimate of protein turnover than does urea. Comparisons of ammonia and urea end products in parenterally fed neonates have not previously been reported. A third and independent way of estimating protein turnover, developed for adults, is to use breath 13CO2 as an end product following administration of [1-13C]leucine. We therefore carried out simultaneous measurements of protein turnover in 10 parenterally fed neonates, using the three end products. The infants were clinically stable, weighed 2.6 +/- 0.2 kg, and received 3.1 +/- 0.2 of amino acid, 2.2 +/- 0.1 of lipids, and an energy intake of 90 +/- 4 (1 kcal = 4.186 kJ). The turnover estimates derived from the 13CO2 and [15N]urea end products were very similar. The [15N]ammonia end product produced values approximately 66% (p less than 0.01) of the other two. We conclude that the ammonia and urea end products probably originate in different precursor pools. The similarity of the urea and breath carbon dioxide results helps validate the use of the urea end product in studying the nitrogen metabolism of parenterally fed neonates. Ideally in future studies two or more end products should be used, since they provide information about different aspects of the neonates' protein metabolism.
P Pencharz; J Beesley; P Sauer; J Van Aerde; U Canagarayar; J Renner; M McVey; D Wesson; P Swyer
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  67     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1989 Jun 
Date Detail:
Created Date:  1989-10-20     Completed Date:  1989-10-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  624-8     Citation Subset:  IM    
Research Institute, Hospital for Sick Children, Toronto, Ont., Canada.
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MeSH Terms
Amino Acids / metabolism
Ammonia / metabolism
Carbon Dioxide / metabolism
Energy Metabolism
Enteral Nutrition*
Glycine / metabolism
Infant, Newborn / metabolism*
Leucine / metabolism
Proteins / metabolism*
Urea / metabolism
Reg. No./Substance:
0/Amino Acids; 0/Proteins; 124-38-9/Carbon Dioxide; 56-40-6/Glycine; 57-13-6/Urea; 61-90-5/Leucine; 7664-41-7/Ammonia

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