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ABSTRACT: To determine the relationship between resting energy expenditure and body cell mass in a group of children with spastic quadriplegic cerebral palsy (SQCP) in comparison with a group of healthy volunteers.
Children with SQCP (n = 13) and healthy control subjects (n = 21) participated in the study. Resting energy expenditure (REE) by indirect calorimetry, as well as body composition measurements were obtained. Those included skinfold measurements, isotope dilution methods for total body water and extracellular water (2H2O or H2(18)O and NaBr, respectively), and bioelectrical impedance analysis. Intracellular water was calculated as total body water minus extracellular water.
Overall REE in children with SQCP was significantly less than in control subjects or from predicted World Health Organization equations. There was a poor correlation between REE and weight or height for children with SQCP and those for control subjects. Children with SQCP showed a higher variance and small improvement in the correlation between REE and lean body mass or intracellular water in comparison with control subjects. Nine of the thirteen children with SQCP had significantly reduced REE per unit of lean tissue or intracellular water. Furthermore, bioelectrical impedance analysis was validated against dilution methods as a suitable technique for measuring total body water (r2 = 0.90, r = 0.95) and extracellular water (r2 = 0.84, r = 0.92) in children with SQCP.
REE in children with SQCP is poorly correlated with body cell mass. We postulate that the central nervous system plays a crucial role in energy regulation. In children with SQCP, individual energy expenditure should be measured so that optimal nutritional status can be achieved. Bioelectrical impedance analysis can be used in this population to measure body water spaces.
Journal of Pediatrics 01/1997; 129(6):870-6. · 4.11 Impact Factor
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ABSTRACT: The requirements for the indispensable amino acids have been determined by a number of different methods. Historically, descriptive or gross measures like growth and nitrogen balance have been used. However, technological advancements in recent years have resulted in the use of more precise and mechanistic metabolic approaches (i.e., plasma amino acid concentrations, amino acid oxidation, indicator amino acid oxidation) to examine requirement. Nevertheless, the current recommendations are still based on nitrogen balance studies. Requirement estimates based on other methodologies, such as plasma amino acid concentrations and direct amino acid oxidation, suggest that the requirement estimates derived from nitrogen balance experiments are too low. However, these higher estimates have also been criticized on conceptual and methodological grounds, resulting in considerable controversy in the area of indispensable amino acid requirements. A new technique, indicator amino acid oxidation, addresses many of the criticisms directed toward the alternative methods and the proposed higher requirement estimates. This paper reviews the current knowledge of amino acid requirements and makes recommendations in light of new information that has been provided from recent indicator amino acid oxidation research. It is concluded that the nitrogen balance-based estimates of amino acid requirement are too low.
Journal of Nutrition 01/1996; 125(12):2907-15. · 3.92 Impact Factor
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ABSTRACT: Amino acids labeled with 13C or deuterium are commonly used in studies of amino acid metabolism. Traditionally, amino acid flux has been estimated by measurement of isotopic enrichment in the plasma pool; however, urine sampling as a noninvasive means of determining isotope enrichment has been increasing. The isotope enrichments and fluxes estimated from plasma and urine sampling were compared when two phenylalanine tracers (L-[1-13C]phenylalanine and L-[ring-2H5]phenylalanine) were intravenously infused for 4 hours in seven healthy men. This is the first evaluation of these isotopes as urinary tracers for assessing amino acid metabolism in adult humans. Before infusion, the mean ratio of plasma to urine (P:U) isotope enrichment was 0.99 +/- 0.03 (SD) and 0.99 +/- 0.02 for [13C]phenylalanine and [13C]tyrosine, respectively (isotope enrichment of [2H5]phenylalanine is zero at baseline). At isotopic steady state, the ratio was 1.06 +/- 0.05, 0.98 +/- 0.03, and 0.60 +/- 0.10 for [13C]phenylalanine, [13C]tyrosine, and [2H5]phenylalanine, respectively. The [13C]phenylalanine isotope showed a high correlation (R2 = .96) between enrichment in plasma and urine. However, use of [2H5]phenylalanine resulted in a significantly higher enrichment in urine than in plasma. Since amino acid flux is inversely related to enrichment, urine sampling would result in an underestimation of flux. The plasma to urine difference is probably due to discrimination of the [2H5]phenylalanine isotope in renal transport; therefore, this isotope may not be suitable for in vivo use where cellular transport mechanisms are involved.
Metabolism 05/1994; 43(4):487-91. · 2.66 Impact Factor
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ABSTRACT: Lysine requirement was determined in seven adult males by examining the effect of varying dietary lysine intake on phenylalanine flux and oxidation under dietary conditions of adequate energy and phenylalanine (14 mg.kg-1 x day-1) and excess tyrosine (40 mg.kg-1 x day-1). Phenylalanine flux was determined from primed, constant intravenous infusions of L-[1-13C]phenylalanine (1.2 mg.kg-1 x day-1) and L-[ring-2H5]phenylalanine (0.5 mg.kg-1 x day-1) and measurement of isotopic enrichments of phenylalanine in plasma. Phenylalanine flux was not affected by graded increases in dietary lysine intake or by the isotope infused. Mean phenylalanine conversion to tyrosine was low (3.4%) and not significantly affected by lysine intake. Phenylalanine oxidation, estimated from the rate of 13CO2 released in expired air during the infusion of L-[1-13C]phenylalanine, decreased linearly as lysine intake increased to a break point that was interpreted as the mean dietary lysine requirement (37 mg.kg-1 x day-1). At lysine intakes of > 37 mg.kg-1 x day-1 phenylalanine oxidation was low and constant. Plasma lysine concentrations supported this estimate of requirement. These data show that: 1) indicator amino acid oxidation can be used as a new method to determine amino acid requirements of humans and 2) the lysine requirement of adult males is three times greater than the World Health Organization recommendation of 12 mg.kg-1 x day-1.
The American journal of physiology 04/1993; 264(4 Pt 1):E677-85.
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ABSTRACT: We examined leucine and lysine metabolism in adult humans (n = 8 and n = 5, respectively) to assess the current estimate of protein requirement. Each subject consumed a controlled isoenergetic liquid diet for three 10-d periods at three intakes of protein, 0.6, 0.8 and 1.0 g.kg-1.d-1, in random order. Measurements of flux and catabolism were determined in each subject in both the fed and postabsorptive states, with a primed, 4-h continuous infusion of L-[1-13C]leucine and L-[alpha-15N]lysine. Fluxes of leucine and lysine were not affected by feeding state or protein intake. Adaptation to different protein intakes did not affect the oxidation of leucine and lysine in the postabsorptive state, but leucine oxidation was significantly higher during the fed period compared with the postabsorptive period at a protein intake of 1.0 g.kg-1.d-1 (P less than 0.05) and tended to be greater (P = 0.06) at an intake of 0.8 g.kg-1.d-1. Nitrogen balance assessed over the last 72 h of each dietary period was positive for all subjects at protein intakes of 0.8 and 1.0 g.kg-1.d-1 of protein and, hence, was consistent with the leucine oxidation data. These data suggest that experiments conducted during the postabsorptive period are not appropriate for estimating protein requirements. Leucine oxidation data obtained during the fed state estimate a protein requirement for young men of between 0.6 and 0.8 g.kg-1.d-1.
Journal of Nutrition 05/1992; 122(4):1000-8. · 3.92 Impact Factor
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ABSTRACT: Whole-body protein metabolism was studied in 11 undernourished cystic fibrosis (CF) patient (7 female), 12 normally nourished CF patients (3 female), 7 anorexia nervosa (AN) patients (all female), and 15 normal control subjects (9 female). Protein turnover was studied by the single dose [15N]glycine method and the cumulative excretion of labeled urinary urea and ammonia. Energy metabolism was studied by open-circuit indirect calorimetry. Contrary to previous reports, no differences were found between the protein turnover of CF groups and the normal control group. However, patients with AN had a negative net protein deposition. Resting energy expenditure was significantly reduced in AN patients and increased in CF patients. The gender of CF patients did not affect protein and energy metabolism but fat mass was higher and fat-free mass was lower in CF females.
American Journal of Clinical Nutrition 02/1992; 55(1):63-9. · 6.67 Impact Factor
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American Journal of Clinical Nutrition 10/1991; 54(3):613-4. · 6.67 Impact Factor
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ABSTRACT: Phenylalanine metabolism was determined in 41 studies of adult males (n = 10) consuming an energy-sufficient diet and receiving graded levels of dietary phenylalanine and excess tyrosine (40 mg.kg-1.day-1). After a dietary adaptation period to either 4.2 or 14.0 mg.kg-1.day-1 of phenylalanine; flux, plasma concentration, oxidation, and conversion to tyrosine were measured at test phenylalanine intakes of 5, 7, 10, 14, 21, 28, or 60 mg.kg-1.day-1. Oxidation was low and constant (1.3 mumol.kg-1.h-1) at intakes at or below 10 mg.kg-1.day-1 and increased linearly above this level. Conversion to tyrosine was minimal (2.1%) at these intakes. Breakpoint analysis showed the phenylalanine requirement with excess tyrosine to be 9.1 mg.kg-1.day-1. Plasma phenylalanine concentrations confirmed this estimate of requirement. Prior adaptation did not significantly affect overall flux, plasma concentration, or oxidation nor did it affect the requirement estimate. With the assumption that tyrosine can supply two-thirds of the aromatic amino acid requirement, these data suggest that the aromatic amino acid requirement should be 30 mg.kg-1.day-1 and the World Health Organization recommendation of 14 mg.kg-1.day-1 is an underestimate.
The American journal of physiology 01/1991; 259(6 Pt 1):E835-43.
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ABSTRACT: A practical and safe heating device for sampling arterialized venous blood from a hand vein was constructed and tested under experimental conditions. Blood chemistry values (pH, pCO2, pO2 and O2 saturation) were measured in nine individuals from blood sampled from an antecubital vein and a hand vein, as well as from a hand vein that had been heated in the handwarmer. Only blood sampled from the heated hand vein gave blood gas values that were consistently in the arterial range. Mean blood gas values were 38.0 +/- 2.5 mmHg, 79.8 +/- 6.8 mmHg and 95.7 +/- 0.9% for pCO2, pO2 and O2 saturation, respectively, for blood sampled from the heated hand vein. No significant difference (P greater than 0.05) was evident in blood gas values whether blood was sampled 15, 30, 45, 60, 75 or 90 min after placing the hand in the heated handwarmer. The handwarmer enables arterialized venous blood sampling after 15 min of warming and is safe to use in any experimental or clinical situation where sampling from an artery is impractical.
Annals of Clinical Biochemistry 08/1990; 27 ( Pt 4):366-72. · 2.17 Impact Factor
