Effect of two amino acid solutions on leucine turnover in preterm infants

Objective: To assess the effect of two different parenteral amino acid mixtures, Trophamine(R) and Primene(R), on leucine turnover in preterm infants. Method: Leucine kinetics were measured with [5,5,5 D3] leucine tracer in 15 infants receiving Trophamine ( group 'T') ( mean birth weight 1,263 g) and 22 who received Primene ( group 'P') ( mean birth weight 1,336 g) during two study periods, within a few hours after birth but before introduction of parenteral amino acid solution, and again at postnatal day 7. The rate of appearance of leucine was calculated from the enrichment of alpha-ketoisocaproic acid in plasma. Results: There were no significant differences in leucine turnover within a few hours after birth in the two groups. In the infants who received Primene leucine turnover on day 7 was significantly lower than in those who received Trophamine (269 +/- 43 vs. 335 +/- 27, p <0.05). Despite a higher intake of leucine in the Trophamine group (108 +/- 10 vs. 77 +/- 8 mu mol center dot kg(-1) center dot h(-1)), leucine released from proteins at day 7 was higher in this group compared to Primene (227 +/- 27 vs. 192 +/- 42 mu mol center dot kg(-1) center dot h(-1)). Conclusions: Primene administration results in lower leucine released from proteins, an estimate of protein breakdown, than Trophamine in preterm infants. Increases in whole body leucine turnover in response to administration of i.v. amino acids is influenced by the composition of the amino acid mixture. The factors responsible for this difference remain to be elucidated. Copyright (C) 2005 S. Karger AG, Basel

Effect of preeclampsia in the mother on the leucine metabolism in the newborn infant

The leucine turnover in newborn infants is influenced by factors such as nutritional state and corticosteroid treatment. Little is known about maternal factors influencing the leucine turnover in the newborn. In order to approach the effect of preeclampsia in the mother on neonatal protein turnover, we studied the leucine turnover in preterm infants soon after birth and again after 7 days. Ten infants from preeclamptic mothers (birth weight 1,280 +/- 240 g, gestational age 31 +/- 2 weeks) and 15 control patients (birth weight 1,320 +/- 210 g, gestational age 30 +/- 2 weeks) were enrolled. The leucine turnover was measured using a primed constant 5-hour intravenous infusion of [1-(13)C]leucine within the first 24 h after delivery and again on day 7 of life. The turnover (leucine flux; micromol.kg(-1).h(-1)) was calculated from the enrichment in alpha-ketoisocaproic acid in plasma. The leucine turnover on day 1 was 300 +/- 65 in the preeclampsia group and 358 +/- 70 in the controls (ANOVA, p < 0.05). The values on day 7 were 474 +/- 73 in the preeclampsia group and 485 +/- 80 in the control group (n.s.). To conclude, the leucine turnover on day 1 is lower in infants of preeclamptic mothers as compared with controls. This difference has disappeared on day 7 of life after receiving the same protein and energy intake