New insights into the methodological issues of the indicator amino acid oxidation method in preterm neonates

作者：de Groof, Femke; Huang, Lisha; Twisk, Jos W. R.; Voortman, Gardi J.; Joemai, Waheeda; Hau, Carmen H.; Schierbeek, Henk; Chen, Chao; Huang, Ying; van Goudoever, Johannes B.^*

来源：Pediatric Research, 2013, 73(5): 679-684.

DOI：10.1038/pr.2013.31

• LYSINE REQUIREMENT
• LEUCINE KINETICS
• INFANTS
• PROTEIN
• PHENYLALANINE
• ADAPTATION
• DIET
• MEN
• NUTRITION
• CHILDREN

BACKGROUND: We determined the effect of adaptation to the study diet on oxidation of the indicator amino acid and the required tracer washout time in preterms. @@@ METHODS: Subjects received a study diet for 6 d that entailed a 50% reduction in leucine. Tracer studies using enterally infused [C-13]bicarbonate and [1-C-13]phenylalanine were performed on days 1, 2, 4, and 6. Breath samples containing (CO2)-C-13 were collected during steady state and measured by infrared spectrometric analysis, and the fraction of 13CO2 recovery from C-13 oxidation ((FCO2)-C-13) was calculated. @@@ RESULTS: Preterm infants (n = 11, birth weight 1.9 +/- 0.1 kg, gestational age 32.6 +/- 1.5 wk) received 166 mg/kg/d of leucine. Baseline enrichment changed significantly at day 1 of the study diet. (FCO2)-C-13 did not change significantly between days 2 and 4 but was significantly lower at day 6. The tracer washout time was determined to be 7.5 h using a biphasic regression analysis. @@@ CONCLUSION: One day of adaptation to a new diet is necessary to adapt to the C-13 enrichment of the study formula before starting infant requirement studies. Adaptation for a period of 5 d results in a protein-sparing response. The minimal time between two studies within the same subject is 7.5 h.

• 出版日期2013-5
• 单位复旦大学