Leucine metabolism at graded amino acid intakes in children receiving parenteral nutrition

Goulet, O.; dePotter, S.; Salas, Juan Rodó; Robert, Jean‐Jacques; Rongier, M.; Hariz, M. Ben; Koziet, J.; Desjeux, J. F.; Ricour, C.

doi:10.1152/ajpendo.1993.265.4.e540

Cited by 21 publications

(20 citation statements)

References 10 publications

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“…4,12 Moreover, the normal rates of leucine oxidation observed in the obese group is a reflection of the tight correlation between plasma leucine and leucine oxidation as reported previously. 28 In agreement with numerous previous studies in children and adolescents, the REE in the obese group was significantly higher than that in the lean control group. 11 We also observed a high degree of correlation between the increased FFM and REE in the obese group (R ¼ 0.82; Po0.01), similar to previous studies in prepubertal children.…”

Section: Discussionsupporting

confidence: 92%

Effect of lifestyle changes on whole-body protein turnover in obese adolescents

et al. 2003

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OBJECTIVE:To investigate the effect of lifestyle changes on whole-body protein turnover (WBPT) in obese adolescents. DESIGN/METHODS: Randomized and controlled nonpharmacological intervention study of WBPT in obese adolescents using stable isotope dilution techniques. SUBJECTS AND MEASUREMENTS:We studied a total of 21 adolescents (11 boys and 10 girls, matched for their pubertal status) of which 15 were obese (age ¼ 15.870.4 y old and BMI ¼ 38.673.3 kg/m 2 ) and six were lean controls (age ¼ 16.070.4 y old and BMI ¼ 21.371.2 kg/m 2 ). The obese subjects were subjected to a randomized controlled lifestyle intervention program that involved moderate physical activity and diet changes for 3 months. A group of lean age-matched subjects was also studied at baseline to compare the WBPT in obese and lean adolescents. The studies were performed during a primed, continuous infusion of L-[1-13 C]leucine. Leucine appearance rate (Leu Ra) was used as an index of whole protein breakdown and the nonoxidative portion of leucine disposal (NOLD) as an index of whole-body protein synthesis. RESULTS: The obese groups showed significantly higher body mass index (BMI), fat mass (FM), percent body fat (%BF), fat-free mass (FFM), resting energy expenditure (REE) and WBPT compared to the lean controls. The intervention program resulted in a redistribution of the parameters of body composition without apparent changes in BMI or body weight. There was a significant decrease in WBPT in the obese intervention group, but not in the obese control group. Insulin levels also decreased significantly in the obese group after intervention but not in the obese control group, whereas the glucose concentrations remained normal in all groups at baseline and also after intervention/or control. CONCLUSIONS: Results from the current study suggest: (i) abonormalities of protein metabolism occur early in the clinical course of obesity and (ii) these abnormalities are modifiable by moderate lifestyle changes in obese adolescents. The mechanism for these changes in WBPT in obese adolescents as well as their impact on specific cardiovascular risk factors and turnover of specific proteins will require further investigation.

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Section: Discussionsupporting

confidence: 92%

Effect of lifestyle changes on whole-body protein turnover in obese adolescents

et al. 2003

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“…Although Ox Leu is known to be tightly dependent on circulating leucine concentration (20), and although plasma leucine concentrations were not measured in the current study, the reduction in Ox Leu is unlikely to result from a lower plasma leucine concentration: plasma KIC concentrations indeed were not different between groups (25 Ϯ 10 M versus 28 Ϯ 6 M), and plasma leucine usually correlates well with plasma KIC levels. Alternatively, glutamine can be readily used as a source of energy, because its conversion by glutaminase and glutamate dehydrogenase leads to ␣-ketoglutarate, which can, in turn, be oxidized in the tricarboxylic acid cycle.…”

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confidence: 57%

Acute Effects of Intravenous Glutamine Supplementation on Protein Metabolism in Very Low Birth Weight Infants: A Stable Isotope Study

et al. 2002

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Although very low birth weight infants are subjected to severe stress and glutamine is now considered a conditionally essential amino acid that may attenuate stress-induced protein wasting in adults, current amino acid solutions designed for neonatal parenteral nutrition do not contain glutamine. To determine whether a short-term supplementation with i.v. glutamine would affect protein metabolism in very low birth weight infants, 13 preterm neonates (gestational age, 28 -30 wk; birth weight, 820 -1610 g) receiving parenteral nutrition supplying 1.5 g · kg Ϫ1 · d Ϫ1 amino acids and approximately 60 nonprotein kcal · kg Ϫ1 · d Ϫ1 were randomized to receive an i.v. supplement made of either 1) natural L-glutamine (0.5 g · kg Ϫ1 · d Ϫ1 ; glutamine group), or 2) an isonitrogenous glutamine-free amino acid mixture (control group), for 24 h starting on the third day of life. On the fourth day of life, they received a 2-h infusion of NaH 13 CO 3 to assess the recovery of 13 C in breath, immediately followed by a 3-h L-[1-13 C]leucine infusion. Plasma ammonia did not differ between the groups. Glutamine supplementation was associated with 1) higher plasma glutamine (629 Ϯ 94 versus 503 Ϯ 83 M, mean Ϯ SD; p Ͻ 0.05, one-tailed unpaired t test), 2) lower rates of leucine release from protein breakdown (Ϫ16%, p Ͻ 0.05) and leucine oxidation (Ϫ35%, p Ͻ 0.05), 3) a lower rate of nonoxidative leucine disposal, an index of protein synthesis (Ϫ20%, p Ͻ 0.05), and 4) no change in protein balance (nonoxidative leucine disposal Ϫ leucine release from protein breakdown, NS). We conclude that although parenteral glutamine failed to enhance rates of protein synthesis, glutamine may have an acute protein-sparing effect, as it suppressed leucine oxidation and protein breakdown, in parenterally fed very low birth weight infants. During the last decade, several clinical trials have produced compelling evidence for a role of glutamine in improving nitrogen balance in adult patients undergoing elective gastrointestinal surgery (1, 2), cholecystectomy (3), or bone marrow transplantation (4). Other studies suggested glutamine might exert a trophic effect on gut as well (5-7).Although preterm infants are exposed to stress-induced protein wasting and intestinal frailty, conventional amino acid solutions designed for neonatal i.v. nutrition do not contain glutamine, because glutamine is classified as nonessential, has relatively poor solubility, and cannot be heat sterilized. Yet Neu et al. (8)

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“…Thus increasing dietary protein induces an increasing inhibition of protein breakdown and, to a lesser extent, an increasing stimulation of synthesis (Waterlow, 1999). These effects may be difficult to detect, however, probably due to variability introduced by study design, subject, diet or methodology, resulting in a variety of outcomes that are often non-significant and challenging to interpret (Hoffer et al 1985;Goulet et al 1993;El Khoury et al 1995;Cayol et al 1997;Forslund et al 1998).…”

Section: Discussionmentioning

confidence: 99%