Splanchnic uptake of leucine in healthy children and in children with cystic fibrosis

An Overview of Parenteral Nutrition from Birth to Adolescence Based on a Composite Fish Oil Containing Lipid Emulsion and a Pediatric Amino Acid Solution

Intestinal failure (IF) is characterized by a critical reduction in functional gut mass below the minimum needed for optimal growth in children. It requires parenteral nutrition (PN) and home-PN (HPN), which is challenging in terms of meeting nutritional needs according to age, growth velocity, clinical situation, and rapid changes in fluid and electrolyte requirements. Due to these complex requirements, age-adapted multi-chamber bags (MCBs) are important additions to the nutrition armamentarium. The launch of composite fish oil (FO)-containing intravenous lipid emulsions (ILEs) heralded the development of MCBs containing these ILEs in combination with a crystalline amino acid solution adapted for pediatric use. The safety and efficacy of lipid and amino acid components in this context have been widely documented in numerous published studies. This narrative manuscript includes a review of the articles published in PudMed, Embase, and Google Scholar up to June 2023 for the age groups of term infants to children and adolescents. Preterm infants with their highly specific demands are not included. It aims to offer an overview of the clinical experience regarding the use of a composite FO-based ILE and a developed specific amino acid solution.

Effects of recombinant human growth hormone on protein turnover in the fasting and fed state in adolescents with Crohn disease

The primary purpose of this study was to test whether recombinant human growth hormone (rhGH) supplementation would enhance protein synthesis and accretion of lean body mass. Eight adolescents (six males and two females; 17.2 +/- 2.6 years; age range, 13.7-21.2 years) participated in a randomized double-blind placebo-controlled cross-over trial of rhGH. We employed stable isotopes to measure proteolysis and protein synthesis during fasting and fed conditions during two 6-month treatment conditions. We also measured bone mineral density (BMD), markers of bone turnover, and body composition. Whole-body proteolysis, phenylalanine catabolism, and protein synthesis did not differ during treatment with rhGH vs. placebo. Enteral nutrition suppressed proteolysis and increased protein synthesis similarly during placebo and rhGH treatments. We conclude that rhGH is unlikely to provide sufficient metabolic benefit to warrant its use as an adjunct treatment in clinically stable adolescents with Crohn disease. A high prevalence of vitamin D deficiency and suboptimal BMD existed, which deserves further investigation and clinical attention.

Chemotherapy does not influence intestinal amino acid uptake in children

Chemotherapy will frequently induce intestinal damage (mucositis). Enteral nutrition is then often withheld for fear of impaired intestinal absorption as shown in animal models. There is no clinical evidence, however, that absorption is indeed compromised during chemotherapy-induced mucositis. The aim of this study was to evaluate systemic availability of dietary amino acids (leucine) during chemotherapy-induced mucositis. We studied eight childhood cancer patients (age 1.5-16 y) on 2 d, i.e. the day before chemotherapy and 3-5 d after. Chemotherapy-induced oral mucositis and diarrhea were scored on a World Health Organization toxicity scale. Stable isotope tracers were used to measure first-pass splanchnic leucine uptake and whole-body leucine kinetics. Patients showed increased mucositis and/or diarrhea toxicity scores (p < 0.0001) after chemotherapy. Systemic availability of enterally administered leucine was not significantly affected by chemotherapy (before 60%, after 90%, p = 0.46). Interestingly, five patients already showed a negative leucine balance before chemotherapy. In conclusion, most children receiving chemotherapy are already catabolic before start of a new cycle of chemotherapy. Amino acid transport as measured by leucine uptake in the intestine is not affected by chemotherapy-induced mucositis.

Acute effects of enteral nutrition on protein turnover in adolescents with Crohn disease

Adults with inactive Crohn disease have been shown to have normal rates of protein turnover when compared with healthy adults. It is not known whether this is true for adolescents with inactive Crohn disease, when rate of protein synthesis must be greater than that of breakdown for normal development. The objective of this study was to determine whether enteral nutrition acutely suppresses proteolysis and increases protein synthesis in adolescents with inactive Crohn disease. Six adolescents (five males/one female; mean age, 15.8 +/- 1.9 y; range, 13.2-17.6 y; mean bone age, 14.6 +/- 1.8 y; range, 12.5-17 y) participated. Leucine (Leu) and phenylalanine (Phe) kinetics were measured using stable isotopes under fasted and fed conditions during a single study visit. In response to enteral nutrition, the endogenous rates of appearance (Ra) of Leu and Phe (reflecting proteolysis) decreased significantly by 40%. The percentages of splanchnic uptake of Leu and Phe were 35 +/- 10% and 13 +/- 12%, respectively. Under fed conditions, utilization of Phe for protein synthesis increased significantly. We conclude that in clinically stable adolescents with Crohn disease, enteral nutrition promotes anabolism by suppressing proteolysis and increasing protein synthesis. Rates of suppression of proteolysis were similar to those reported previously in normal children.

Effect of minimal enteral feeding on splanchnic uptake of leucine in the postabsorptive state in preterm infants

We conducted a controlled, randomized trial to study the effect of minimal enteral feeding on leucine uptake by splanchnic tissues, as an indicator of maturation of these tissues, in preterm infants in the first week of life. Within a few hours after birth, while receiving only glucose, a primed constant infusion of [1-(13)C]-leucine was started and continued for 5 h via the nasogastric tube, whereas 5,5,5 D3-leucine was infused intravenously (for both tracers, priming dose 2 mg/kg, continuous infusion 2 mg/kg/h). Patients were thereafter randomized to receive solely parenteral nutrition (C), parenteral nutrition and 20 mL breast milk/kg/d (BM), or parenteral nutrition and 20 mL formula/kg/d (F). On d 7, the measurements were repeated, after discontinuing the oral intake for 5 h. Fourteen infants were included in group C, 12 in group BM, and 12 in group F. There was no difference in energy intake or nitrogen balance at any time. On d 1, plasma enrichment for the nasogastric tracer was lower than for the intravenous tracer for all three groups, both for leucine and for alpha-keto-isocaproic acid. On d 7, the enrichment for leucine and alpha-keto-isocaproic acid for the nasogastric tracer was lower than for the intravenous tracer for the groups BM and F (BM: 3.65 +/- 1.20 nasogastric versus 4.64 +/- 0.64 i.v.; F: 4.37 +/- 1.14 nasogastric versus 5.21 +/- 0.9 i.v.). In the control group, there was no difference between tracers. The lower plasma enrichment for the nasogastric tracer compared with the intravenous tracer suggests uptake of leucine by the splanchnic tissues. We conclude that minimal enteral feeding--even in low volumes of 20 mL/kg/d--increases the leucine uptake by the splanchnic tissue. We speculate that this reflects a higher protein synthesis of splanchnic tissues in the groups receiving enteral nutrition.