Lysine kinetics in preterm infants: the importance of enteral feeding

van der Schoor, S R D

doi:10.1136/gut.53.1.38

Cited by 35 publications

(29 citation statements)

References 35 publications

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“…The background (baseline) values of the 13 C label in expiratory air did not differ between the two study days (study d 1: 1.0997 Ϯ 0.0036 and study d 2: 1.0956 Ϯ 0.0001 APE; p ϭ 0.3) and were in the same range as we have found previously (8,20). Similarly, baseline enrichments of [U- 13 (6,8). To determine splanchnic and whole body glutamine kinetics, we used plateau glutamine enrichment values from plasma and labeled carbon dioxide in expiratory air (Tables 2 and 4).…”

Section: Resultssupporting

confidence: 70%

“…A similar finding was observed in preterm infants regarding glutamate oxidation. Almost 90% of the used glutamate in the first pass was oxidized, while essential amino acids such as leucine and lysine were not oxidized in preterm infants (6). Furthermore, glucose oxidation (10 kcal ⅐ kg Ϫ1 ⅐ d Ϫ1 ) contributed five times as much as glutamate oxidation (1.7 kcal ⅐ kg Ϫ1 ⅐ d Ϫ1 ) to splanchnic CO 2 production, indicating that glucose is the major source of energy in the human neonatal intestine (29).…”

Section: Discussionmentioning

confidence: 99%

“…13 C]label in the expiratory air with the rate of appearance of glutamine (6,8,25). The fraction of glutamine oxidized using the enrichment of the i.v.…”

Section: Methodsmentioning

confidence: 99%

“…Dietary digested amino acids can be used for intestinal energy generation; for conversion via transamination into other amino acids, metabolic substrates, and biosynthetic intermediates; and for tissue growth. Previous studies in neonates showed a considerable intestinal amino acid metabolism, with some amino acids that are extensively catabolized, while others are presumed to be incorporated to a great extend in mucosal cellular or excreted (glyco-)proteins (5)(6)(7)(8)(9).…”

Section: (Pediatr Res 67: 194-199 2010)mentioning

confidence: 99%

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Majority of Dietary Glutamine Is Utilized in First Pass in Preterm Infants

et al. 2010

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Glutamine is a conditionally essential amino acid for very low-birth weight infants by virtue of its ability to play an important role in several key metabolic processes of immune cells and enterocytes. Although glutamine is known to be used to a great extend, the exact splanchnic metabolism in enterally fed preterm infants is unknown. We hypothesized that preterm infants show a high splanchnic first-pass glutamine metabolism and the primary metabolic fate of glutamine is oxidation. Five preterm infants (mean Ϯ SD birth weight 1.07 Ϯ 0.22 kg and GA 29 Ϯ 2 wk) were studied by dual tracer ([U-13 C]glutamine and [ 15 N 2 ]glutamine) crossover techniques on two study days (at postnatal week 3 Ϯ 1 wk). Splanchnic and whole-body glutamine kinetics were assessed by plasma isotopic enrichment of [U- CO 2 enrichments. Mean fractional first-pass glutamine uptake was 73 Ϯ 6% and 57 Ϯ 17% on the study days. The splanchnic tissues contributed for a large part (57 Ϯ 6%) to the total amount of labeled carbon from glutamine retrieved in expiratory air. Dietary glutamine is used to a great extent by the splanchnic tissues in preterm infants and its carbon skeleton has an important role as fuel source. A fter birth, very low-birth weight infants (VLBW) infants are exposed to stress-induced protein wasting and intestinal infirmity. Given the key role of the intestine in the conservation of neonatal wellness, there has been substantial interest in the magnitude of first-pass splanchnic metabolism of dietary amino acids (1-4). Dietary digested amino acids can be used for intestinal energy generation; for conversion via transamination into other amino acids, metabolic substrates, and biosynthetic intermediates; and for tissue growth. Previous studies in neonates showed a considerable intestinal amino acid metabolism, with some amino acids that are extensively catabolized, while others are presumed to be incorporated to a great extend in mucosal cellular or excreted (glyco-)proteins (5-9).Glutamine, a conditionally essential amino acid for VLBW infants, might play a versatile role in both maintenance of gut trophicity and in nitrogen homeostasis by interorgan shuttling of carbon and nitrogen. Glutamine plays a central role as a substrate for a number of aminotransferases that are responsible for the synthesis of asparagine, glucosamine, NAD, purines, and pyrimidines (10). In animal studies, the small intestine is a major organ for glutamine utilization (11,12). Moreover, in in vitro experiments, glutamine has been shown to be the most important oxidative fuel source for rapidly dividing cells such as cells from gut and the immune system (13,14). In human adults, Matthews et al. (15,16) found that the splanchnic extraction of glutamine was 60 to 80% of the dietary intake, of which oxidation was a major metabolic fate. In preterm infants, Darmaun et al. (5) showed that glutamine is extensively extracted from the enteral lumen. Whether preterm infants sequester and oxidize the same amount of dietary glutamine has not yet been ...

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Section: Resultssupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

“…13 C]label in the expiratory air with the rate of appearance of glutamine (6,8,25). The fraction of glutamine oxidized using the enrichment of the i.v.…”

Section: Methodsmentioning

confidence: 99%

Section: (Pediatr Res 67: 194-199 2010)mentioning

confidence: 99%

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Majority of Dietary Glutamine Is Utilized in First Pass in Preterm Infants

et al. 2010

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“…Humans also show considerable intestinal amino acid metabolism (4,5) and the metabolic rate is even higher in preterm infants. Previous studies showed that first-pass metabolism of leucine in newborns is twice that of adults (6) and that in preterm infants, a great amount of dietary lysine is used in first pass as well (7).…”

mentioning

confidence: 99%

Splanchnic Oxidation Is the Major Metabolic Fate of Dietary Glutamate in Enterally Fed Preterm Infants

et al. 2007

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ABSTRACT:The intestine is a major site of amino acid metabolism, especially in neonates. The energy needed for the metabolic processes in neonatal animals is derived from dietary glucose and amino acids. No data are available showing that dietary amino acids function as intestinal fuel source in human neonates as well. We hypothesized that preterm infants show a high splanchnic first-pass glutamate metabolism and the primary metabolic fate of glutamate is oxidation. Five preterm infants (birth weight 1.2 Ϯ 0.2 kg, gestational age 29 Ϯ 1 wk) were studied by dual tracer ([U- T he splanchnic tissues have much higher energy expenditure and protein synthesis rates than expected based on their weight. Studies in neonatal animals found that up to 50% of the dietary protein intake in the portal drained viscera (intestines, pancreas, spleen, and stomach) is used for protein turnover and biosynthetic pathways; from 10% to 20% is used for whole-body energy expenditure (1-3). Humans also show considerable intestinal amino acid metabolism (4,5) and the metabolic rate is even higher in preterm infants. Previous studies showed that first-pass metabolism of leucine in newborns is twice that of adults (6) and that in preterm infants, a great amount of dietary lysine is used in first pass as well (7).Glutamate plays a pivotal role in human metabolism. It provides a critical link between carbohydrate and amino acid metabolism. Glutamate is the obligatory precursor of glutamine; it plays a central role in all transamination reactions in the body and also functions as a neurotransmitter. In addition, dietary glutamate is a major substrate for glutathione (GSH) synthesis (8). Animal studies showed that the gut of infant piglets metabolizes virtually all the enteral glutamate during absorption (9) and that glutamate it is an important oxidative substrate for the intestinal mucosa (10). In human adults, most of the dietary glutamate (88%) is metabolized in first-pass as well (11) and is oxidized to a great extent in the splanchnic region (12). These studies in animals and adult humans suggest that dietary glutamate serves as an important metabolic fuel source in the intestine. If so, this may have a particular impact on the nutritional needs of preterm infants. The intestine of preterm infant is immature and has a low tolerance to enteral feeding. Yet, enteral feeding is a must for intestinal maturation and the growth and development of other organs. Much effort should be directed toward understanding the nutritional needs of the intestine of preterm infants. The present study was developed to extend the previously mentioned observations made in animals and adult humans and thus gain more insight into the nutritional needs of infants.In the present study, we, therefore, investigated 1) the effect of first-pass splanchnic uptake of glutamate and 2) the metabolic fate of the used glutamate in the splanchnic bed of enterally fed preterm infants. Glutamate kinetics in the splanchnic region were studied by dual, primed, constant i.v. and en...

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Assessment of Amino Acid Requirement in Children Using Stable Isotopes

Groof

Schierbeek

2017

Mass Spectrometry and Stable Isotopes in Nutritional and Pediatric Research

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Lysine kinetics in preterm infants: the importance of enteral feeding

Cited by 35 publications

References 35 publications

Majority of Dietary Glutamine Is Utilized in First Pass in Preterm Infants

Majority of Dietary Glutamine Is Utilized in First Pass in Preterm Infants

Splanchnic Oxidation Is the Major Metabolic Fate of Dietary Glutamate in Enterally Fed Preterm Infants

Assessment of Amino Acid Requirement in Children Using Stable Isotopes

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