Open AccessA Kinetic Study of Leucine Metabolism in Severely Burned Patients Comparison Between a Conventional and Branched-Chain Amino Acid-Enriched Nutritional Therapy
Author(s) -
YongMing Yu,
David Wagner,
J. C. Walesreswski,
John F. Burke,
Ver R. Young
Publication year - 1988
Publication title -
annals of surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.153
H-Index - 309
eISSN - 1528-1140
pISSN - 0003-4932
DOI - 10.1097/00000658-198804000-00009
Subject(s) - leucine , nitrogen balance , medicine , amino acid , protein catabolism , urea , protein turnover , protein metabolism , metabolism , enteral administration , endocrinology , branched chain amino acid , parenteral nutrition , zoology , biochemistry , protein biosynthesis , chemistry , biology , nitrogen , organic chemistry
A cross-over design study was used to examine the metabolic consequences of enteral feeding for 48 to 96 hours with either a branched-chain amino acid (BCAA)-enriched (44% BCAA) or a conventional egg protein formulation in 12 severely burned adult patients. A stable isotope labeled leucine (L-1-13C-leucine) tracer approach was used to measure leucine flux and oxidation and to estimate rates of whole body protein synthesis and breakdown. Additionally, 15N2-urea and 6,6-2H-glucose were administered to assess the status of urea and glucose kinetics with these two nutritional treatments. Average patient age was 54 years, and average burn surface area was 36%. Studies were conducted at an average of 25 days postburn. Leucine flux and oxidation were significantly (p less than 0.01, by paired t-test) elevated with BCAA feeding as compared to the egg protein formulation. However, there were no significant differences in the rates of leucine incorporation into, or release from, proteins (p greater than 0.05) between the two dietary periods. Mean rates of body protein synthesis and breakdown for each diet were about twice the rates reported for healthy young adults. Apparent nitrogen balance measurements were not statistically different (p greater than 0.1) between the two diet periods. Furthermore, urea and glucose kinetics failed to show significant differences between the two diet periods. It appears from these results that the major consequences of increased intake of leucine from the BCAA formula is an enhanced rate of leucine oxidation. In conclusion, (1) the availability of BCAAs is not rate-limiting for enhanced protein synthesis in burn patients, and (2) the use of enriched BCAA formulas in burn therapy does not appear to offer advantages over a routinely used enteral egg protein formula, at least based on the present determinations.