Cord Blood Amino Acid Concentrations from Neonates of 23—41 Weeks Gestational Age

Pittard, William B.; Geddes, Kitty M.; Picone, Thomas A.

doi:10.1177/0148607188012002167

Cited by 17 publications

(9 citation statements)

References 13 publications

(1 reference statement)

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“…With the exception of the concentrations of threonine and tyrosine in groups 2 and 3, the mean concentrations of all were within the 95% confidence limits (+2 SD) of cord plasma concentrations between 29 wk gestation and term (30).…”

Section: Discussionmentioning

confidence: 60%

Evaluation of a Mathematical Model for Predicting the Relationship between Protein and Energy Intakes of Low-Birth-Weight Infants and the Rate and Composition of Weight Gain

et al. 1994

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ABSTRACT'. A model for predicting the relationship between protein and energy intakes of low-birth-weight (LBW) infants and the rate and composition of weight gain is described. It is based on linear multiple regression equations summarizing the rates of weight gain, nitrogen retention, and energy retention of 101 previously studied LBW infants fed protein intakes ranging from 2.25 to 3.9 g. kg-' .d-' and concomitant energy intakes ranging from 115 to 147 kcal. kg-'.d-' plus current theory concerning nutrient retention and body composition. To test the validity of the model, three combinations of protein and energy intake predicted by the model to result in specific rates and compositions of weight gain were fed to 44 LBW infants, and the observed rates of weight gain, protein accretion, and fat accretion were compared with the rates predicted by the model. Differences in these and other outcome variables between two of the groups, the intakes of which differed only in energy, also were compared to provide additional insight into the effect of concomitant energy intake on protein utilization. Across groups, actual outcomes correlated closely with predicted outcomes, supporting the validity of the model for the total population. However, outcomes of individual infants deviated as much as 30% from predicted outcomes; the magnitude of the deviation was independent of birth weight, gestational age, or size for gestational age. In addition, the mean rate of protein accretion of the group fed the highest protein/ energy ratio was significantly less than predicted. The higher mean urinary nitrogen excretion as well as blood urea nitrogen and plasma amino acid concentrations of this group versus the group that received a similar protein intake with a higher energy intake suggest that the higher energy intake improved nitrogen utilization. In toto, the data support the concept that the rate and composition of weight gain of LBW infants can be manipulated by intake; however, for individual infants, the extent of manipulation seems to be dependent on as-yet-unidentified inherent biologic variables. (Pediatr Res 35: [704][705][706][707][708][709][710][711][712] 1994) Abbreviations LBW, low birth weight Current guidelines for feeding LBW infants stress the importance of achieving as soon after birth as possible a rate of weight gain that is at least equal to or, preferably, greater than the intrauterine rate (1, 2). A number of studies have demonstrated that even the higher rates of weight gain can easily be achieved but that the accompanying rates of fat accretion are as much as 3-fold greater than the intrauterine rate (3-8). The desirability of such high rates of fat accretion are unknown. For most populations, they are considered undesirable, but this may not be true for the LBW infant who is born with limited fat stores. Moreover. approximately 40% of the weight gained by term infants over the first 4 mo of life appears to be fat (9), raising the possibility that high rates of fat accretion are unavoidable during ear...

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Section: Discussionmentioning

confidence: 60%

Evaluation of a Mathematical Model for Predicting the Relationship between Protein and Energy Intakes of Low-Birth-Weight Infants and the Rate and Composition of Weight Gain

et al. 1994

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“…The blood acid base status was within normal limits in all infants throughout the study period. With the exception of threonine and tyrosine, which were mildly elevated, the mean concentrations of all plasma amino acids were within the 95% confidence limits (Ϯ2 SD) of cord plasma concentrations of similar gestational age preterm infants (22). The total plasma amino acid concentrations of infants on the high-carbohydrate diets were significantly lower than those of infants on the high-fat diets (3540 Ϯ 474 versus 4092 Ϯ 454 mol/L, p Ͻ 0.01 in groups 2 versus 1 and 3455 Ϯ 296 versus 3857 Ϯ 411 mol/L, p Ͻ 0.05 in groups 4 versus 3, respectively); however, again, these differences were already apparent by the time the infants achieved full enteral intakes of the formulas.…”

Section: Effect Of Quality Of Energy Intakementioning

confidence: 62%

Effects of Quality of Energy Intake on Growth and Metabolic Response of Enterally Fed Low-Birth-Weight Infants

et al. 2001

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Carbohydrate and fat may vary in their ability to support protein accretion and growth. If so, variations in the source of nonprotein energy might be used to therapeutic advantage in enterally fed low-birth-weight infants. To test the hypothesis that high-carbohydrate diets are more effective than isocaloric highfat diets in promoting growth and protein accretion, low-birthweight infants weighing 750 -1600 g at birth were randomized in a double blind study to receive one of five formulas differing only in the quantity and quality of nonprotein energy. Groups 1, 2, and control received 130 kcal·kg -1 ·d -1 with 35, 65, and 50% of the nonprotein energy as carbohydrate. Groups 3 and 4 received energy intake of 155 kcal·kg -1 ·d -1 with 35 and 65% of the nonprotein energy as carbohydrate. Protein intake of all groups was 4 g·kg -1 ·d -1 . Growth and metabolic responses were followed weekly, and macronutrient balances including 6-h indirect calorimetry were performed biweekly. Greater rates of weight gain and nitrogen retention were observed at high-carbohydrate intake compared with high-fat intake at both gross energy intakes. Greater rates of energy storage and an increase in skinfold thickness were observed in group 4 (high-energy highcarbohydrate diet) despite higher rates of energy expenditure. These data support the hypothesis that at isocaloric intakes, carbohydrate is more effective than fat in enhancing growth and protein accretion in enterally fed low-birth-weight infants. However, a diet with high-energy and high-carbohydrate content also results in increased fat deposition. The American Academy of Pediatrics has suggested that a logical goal for nutritional support of the preterm LBW infant is to achieve postnatal growth approximating that of a normal fetus of the same postconceptional age (1, 2). Attempts to achieve this goal by feeding enriched diets have been successful in supporting the intrauterine rate of weight gain (3-7), but invariably these diets lead to a disproportionate increase in body fat. The reasons for this postnatal failure to maintain the high fetal rates of protein accretion relative to fat deposition are unknown. One difference between fetal and neonatal life is the relatively greater dependence of the fetus on carbohydrate versus fat as an energy source. If the fetus is relatively more dependent on carbohydrate than fat, then it is possible that the same is true of the fetus ex utero, i.e. the preterm LBW infant. This reintroduces a question of long-standing concern in developmental nutrition, namely, do carbohydrate and fat differ in some fundamental way in their ability to support protein synthesis? Indeed, there is experimental evidence that supports the hypothesis that calorie for calorie, utilization of carbohydrate as an energy source is more effective than fat in supporting protein accretion (8 -11); other research, however, asserts that this effect is transient (12). In enterally fed LBW infants, this hypothesis remains untested.LBW infants are ideal subjects for studying th...

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“…No differences were detected in total serum protein (44 Ϯ The main PAA results are presented in Table 5 and compared with umbilical cord blood reference values (15). Total essential amino acids (sum of lysine, valine, phenylalanine, methionine, tryptophan, threonine, histidine, leucine, isoleucine) were greater in infants fed the HiPro formula (p Ͻ 0.05) but were less than the cord reference value.…”

Section: Resultsmentioning

confidence: 99%

“…However, PAA in infants fed the HiPro formula were still less than cord reference values (15). Does this mean that protein intake was still inadequate?…”

Section: Protein-energy Needs Of Pre-term Infantsmentioning

confidence: 93%

High Protein Pre-Term Infant Formula: Effect on Nutrient Balance, Metabolic Status and Growth

et al. 2006

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Several lines of evidence suggest that formula with protein content of 3.0 g/100 kcal does not fully meet the protein needs of very-low-birth weight infants. Our purpose was to compare nitrogen balance, metabolic status and growth in infants fed a standard (3.0 g/100 kcal; RegPro) and high (3.6 g/100 kcal; HiPro) protein infant formula. Infants were fed both formulas, each formula for one week in balanced cross-over design. Metabolic status was monitored throughout. Nutrient balance and plasma amino acids were determined at the end of each week. Data were analysed using a linear mixed model. Eighteen infants were studied. Nine infants received the RegPro and nine received HiPro formula first. Nitrogen intake, absorption and retention were greater with the HiPro formula. None of the infants developed uremia or metabolic acidosis but retinol-binding-protein and weight gain were greater with the HiPro formula. Increased protein accretion paralleled by better weight gain without evidence of metabolic stress indicates that a formula with a protein content of 3.6 g/100 kcal better meets protein needs in these rapidly-growing infants. Further studies are needed to determine whether these short-term outcomes will be translated into long-term benefits. T here is compelling evidence that premature infants frequently do not receive protein intakes that meet their needs (1,2). In the case of formula-fed infants, one critical reason is that pre-term formulas contain too little protein. The protein needs of premature infants are reasonably well established based on the factorial method and experimental data. By one estimate, protein requirements are 4.0 g/kg/d for infants weighing less than 1200 g, decreasing to 3.9 g/kg/d for infants weighing 1200 -1500 g (3). Expressed per unit of energy, the requirements for protein are 3.8 g/100 kcal for infants weighing 500 -700 g, decreasing gradually to 3.1 g/100 kcal for infants weighing 1200 -1500 g (3).A formula that provides 3.0 g/100 kcal, therefore, cannot provide an adequate intake of protein. If needs of these infants are to be met, a formula must provide more than 3.0 g/100 kcal. We, therefore, hypothesized that a formula with a protein concentration of 3.6 g/100 kcal would lead to greater nitrogen retention and greater short term weight gain than a formula with a protein concentration of 3.0 g/100 kcal. The present study was designed to test this hypothesis. METHODS AND PROCEDURESStudy design. The study design was based on a previous study in pre-term infants and is outlined in Table 1 (4). It comprised of 2 one-week comparison periods during which each formula was fed. It was conducted in a double blind fashion, with the sequence of formula feeding randomly determined and balanced. Immediately before the first study formula was fed, baseline (anthropometric, metabolic) determinations were made. After a minimum equilibration period of 72 h, anthropometric and metabolic determinations were repeated and the first metabolic balance study was begun. At the end of the fi...

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Cord Blood Amino Acid Concentrations from Neonates of 23—41 Weeks Gestational Age

Cited by 17 publications

References 13 publications

Evaluation of a Mathematical Model for Predicting the Relationship between Protein and Energy Intakes of Low-Birth-Weight Infants and the Rate and Composition of Weight Gain

Evaluation of a Mathematical Model for Predicting the Relationship between Protein and Energy Intakes of Low-Birth-Weight Infants and the Rate and Composition of Weight Gain

Effects of Quality of Energy Intake on Growth and Metabolic Response of Enterally Fed Low-Birth-Weight Infants

High Protein Pre-Term Infant Formula: Effect on Nutrient Balance, Metabolic Status and Growth

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