Acid In Preterm Infants Research Articles

Polyunsaturated fatty acids in preterm infants: opportunity to revisit tenets of study design and reporting for nutrient intervention trials.

Polyunsaturated fatty acids in preterm infants: opportunity to revisit tenets of study design and reporting for nutrient intervention trials.

Modification of serum fatty acids in preterm infants by parenteral lipids and enteral docosahexaenoic acid/arachidonic acid: A secondary analysis of the Mega Donna Mega trial

Preterm infants risk deficits of long-chain polyunsaturated fatty acids (LCPUFAs) that may contribute to morbidities and hamper neurodevelopment. We aimed to determine longitudinal serum fatty acid profiles in preterm infants and how the profiles are affected by enteral and parenteral lipid sources. Cohort study analyzing fatty acid data from the Mega Donna Mega study, a randomized control trial with infants born <28 weeks of gestation (n=204) receiving standard nutrition or daily enteral lipid supplementation with arachidonic acid (AA):docosahexaenoic acid (DHA) (100:50mg/kg/day). Infants received an intravenous lipid emulsion containing olive oil:soybean oil (4:1). Infants were followed from birth to postmenstrual age 40 weeks. Levels of 31 different fatty acids from serum phospholipids were determined by GC-MS and reported in relative (mol%) and absolute concentration (μmol l-1) units. Higher parenteral lipid administration resulted in lower serum proportion of AA and DHA relative to other fatty acids during the first 13 weeks of life (p<0.001 for the 25th vs the 75th percentile). The enteral AA:DHA supplement increased the target fatty acids with little impact on other fatty acids. The absolute concentration of total phospholipid fatty acids changed rapidly in the first weeks of life, peaking at day 3, median (Q1-Q3) 4452 (3645-5466) μmol l-1, and was positively correlated to the intake of parenteral lipids. Overall, infants displayed common fatty acid trajectories over the study period. However, remarkable differences in fatty acid patterns were observed depending on whether levels were expressed in relative or absolute units. For example, the relative levels of many LCPUFAs, including DHA and AA, declined rapidly after birth while their absolute concentrations increased in the first week of life. For DHA, absolute levels were significantly higher compared to cord blood from day 1 until postnatal week 16 (p<0.001). For AA, absolute postnatal levels were lower compared to cord blood from week 4 throughout the study period (p<0.05). Our data show that parenteral lipids aggravate the postnatal loss of LCPUFAs seen in preterm infants and that serum AA available for accretion is below that in utero. Further research is needed to establish optimal postnatal fatty acid supplementation and profiles in extremely preterm infants to promote development and long-term health. ClinicalTrials.gov, identifier: NCT03201588.

Neonatal Docosahexaenoic Acid in Preterm Infants and Intelligence at 5 Years

BackgroundDocosahexaenoic acid (DHA) is a component of neural tissue. Because its accretion into the brain is greatest during the final trimester of pregnancy, infants born before 29 weeks’ gestation do not receive the normal supply of DHA. The effect of this deficiency on subsequent cognitive development is not well understood.MethodsWe assessed general intelligence at 5 years in children who had been enrolled in a trial of neonatal DHA supplementation to prevent bronchopulmonary dysplasia. In the previous trial, infants born before 29 weeks’ gestation had been randomly assigned in a 1:1 ratio to receive an enteral emulsion that provided 60 mg of DHA per kilogram of body weight per day or a control emulsion from the first 3 days of enteral feeds until 36 weeks of postmenstrual age or discharge home, whichever occurred first. Children from 5 of the 13 centers in the original trial were invited to undergo assessment with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) at 5 years of corrected age. The primary outcome was the full-scale intelligence quotient (FSIQ) score. Secondary outcomes included the components of WPPSI.ResultsA total of 1273 infants underwent randomization in the original trial; of the 656 surviving children who had undergone randomization at the centers included in this follow-up study, 480 (73%) had an FSIQ score available — 241 in the DHA group and 239 in the control group. After imputation of missing data, the mean (±SD) FSIQ scores were 95.4±17.3 in the DHA group and 91.9±19.1 in the control group (adjusted difference, 3.45; 95% confidence interval, 0.38 to 6.53; P=0.03). The results for secondary outcomes generally did not support that obtained for the primary outcome. Adverse events were similar in the two groups.ConclusionsIn infants born before 29 weeks’ gestation who had been enrolled in a trial to assess the effect of DHA supplementation on bronchopulmonary dysplasia, the use of an enteral DHA emulsion until 36 weeks of postmenstrual age was associated with modestly higher FSIQ scores at 5 years of age than control feeding. (Funded by the Australian National Health and Medical Research Council and Nu-Mega Ingredients; N3RO Australian New Zealand Clinical Trials Registry number, ACTRN12612000503820.)

Characteristics of the metabolic status of children of the first year of life with protein-energy deficiency depending on the gestational age at birth.

Comparative analysis of energy-plastic exchange indicators in mature and premature children of the first year of life in the development of protein-energy malnutrition (PEM) was carried out. Unidirectional changes are revealed, including an increase in creatinine, lactate and creatine phosphokinase activity levels, suggesting a n increasing muscle mass deficit against the background of glucose anaerobic oxidation activation. In preterm infants, glucose and triacylglicerine levels decrease, which reflects uncompensated insufficiency of energy substrates and, accordingly, ATP level. Multidirectional deviations in metabolism are pyruvate and ATP content: increase in full-term infants and decrease in preterm infants, that should be taken into account when monitoring condition of children with PEM. A significant decrease of pyruvic acid in preterm infants against the background of the levels of total protein, albumin, hemoglobin, and transferrin, not exceeding reference values, can obviously testify to the active use of this integral metabolite to maintain the fund of substituted amino acids. Development of this pathology in both mature and premature infants creates a pre-morbid background for iron deficiency anemia-diagnostic panel, which should be supplemented by calculation of transferrin saturation coefficient. Regardless of gestational age in childbirth during the formation of PEM, the lipid spectrum is rearranged according to atherogenic type: at normal values of total cholesterol, there is a significant increase in low and very low density lipoproteins with an increase in the atherogenicity coefficient. This singles out children with the pathology in question as a risk group for the development of the atherosclerotic process later, which justifies the recommendation to control the lipid profile in children of the first year of life.

A More Comprehensive Approach to the Neuroprotective Potential of Long-Chain Polyunsaturated Fatty Acids in Preterm Infants Is Needed-Should We Consider Maternal Diet and the n-6:n-3 Fatty Acid Ratio?

There is growing evidence that long-chain polyunsaturated fatty acids (LCPUFAs) are of importance for normal brain development. Adequate supply of LCPUFAs may be particularly important for preterm infants, because the third trimester is an important period of brain growth and accumulation of arachidonic acid (n-6 LCPUFA) and docosahexaenoic acid (n-3 LCPUFA). Fatty acids from the n-6 and n-3 series, particularly, have important functions in the brain as well as in the immune system, and their absolute and relative intakes may alter both the risk of impaired neurodevelopment and response to injury. This narrative review focuses on the potential importance of the n-6:n-3 fatty acid ratio in preterm brain development. Randomized trials of post-natal LCPUFA supplementation in preterm infants are presented. Pre-clinical evidence, results from observational studies in preterm infants as well as studies in term infants and evidence related to maternal diet during pregnancy, focusing on the n-6:n-3 fatty acid ratio, are also summarized. Two randomized trials in preterm infants have compared different ratios of arachidonic acid and docosahexaenoic acid intakes. Most of the other studies in preterm infants have compared formula supplemented with arachidonic acid and docosahexaenoic acid to un-supplemented formula. No trial has had a comprehensive approach to differences in total intake of both n-6 and n-3 fatty acids during a longer period of neurodevelopment. The results from preclinical and clinical studies indicate that intake of LCPUFAs during pregnancy and post-natal development is of importance for neurodevelopment and neuroprotection in preterm infants, but the interplay between fatty acids and their metabolites is complex. The best clinical approach to LCPUFA supplementation and n-6 to n-3 fatty acid ratio is still far from evident, and requires in-depth future studies that investigate specific fatty acid supplementation in the context of other fatty acids in the diet.

Dynamic changes in blood amino acid concentrations in preterm infants in different nutritional periods.

Neonatal nutrition is critical for the growth and development of preterm infants. Dynamic changes in the amino acid profiles in preterm infants of different gestational ages and in different nutritional periods were investigated. Premature infants who received parenteral nutrition support after birth were enrolled and divided into four groups based on their gestational ages. Blood samples were collected as a dried blood spot before nutritional support, and in the total parenteral nutrition, partial parenteral nutrition, and total enteral nutrition periods. Amino acid concentrations were detected in the samples by liquid chromatography tandem mass spectrometry and compared between the different nutritional periods and gestational ages. Samples from 124 premature infants were statistically analyzed. Concentrations of all amino acids, except glutamine, were statistically different at distinct nutritional periods. Threonine and aspartic acid concentrations gradually increased, while valine, methionine, phenylalanine, and glycine concentrations gradually decreased with the transition from TPN to TEN. At different gestational ages, significant differences were observed in the concentrations of seven amino acids only in the PPN period but not in the others. The concentrations of amino acids in preterm infants vary with nutritional period.

High-dose parenteral amino acid intake in very low birthweight infants: what is the current evidence?

There is uncertainty regarding optimal dosing for parenteral amino acids in preterm infants and wide variability exists in clinical practice. There is new data from clinical trials trying to address these concerns. We review the recent evidence on parenteral high-dose amino acid intake in very low birth weight (VLBW) neonates with a focus on relevant clinical outcomes. Preterm infants often receive less protein than intended in the first week of life. Parenteral amino acid administration in doses that exceed requirements, however, leads to increased oxidation and higher blood urea concentrations. Amino acid doses greater than 3.5 g/kg/day have not shown to improve mortality, neonatal morbidities including sepsis, necrotizing enterocolitis, chronic lung disease, growth parameters or neurodevelopmental outcomes at 2 years of age. Parenteral amino acid administration in VLBW infants should be initiated soon after birth at a dose of at least 1.5 g/kg/day to maintain anabolism. The maximum dose for parenteral amino acid should be between 2.5 and 3.5 g/kg/day, with adequate nonprotein calories and micronutrients to ensure efficient protein utilization and growth.

Progression of Gastric Acid Production in Preterm Neonates: Utilization of In-vitro Method.

Background: Limited studies are done regarding ability to produce gastric acid in preterm infants and most studies used in vivo method of assessing gastric pH.Objectives: To assess the feasibility of using an in vitro method of measuring gastric pH in babies ≤ 28 weeks gestational age (GA) and determine whether changes in gastric pH differ with gestational age, mode of delivery, and use of antenatal steroids.Design/Methods: Prospective study that enrolled extremely low birth weight (ELBW) babies. Gastric aspirate collected before feeding. In vitro testing of gastric aspirates for pH were done on days of life 1, 3, 5, 7, 14, and 28 by using pH electrode. The pH was measured on each sample in triplicate, mean calculated and used for data analysis. Stastical methods included descriptive statistics, t-tests and repeated measures ANOVA.Results: 29 subjects ≤ 28 weeks or birth weight ≤ 1,000 g were enrolled. No significant change was noted in pH measurements over time. Antenatal steroids and mode of delivery did not affect gastric acid pH.Conclusion: The in vitro method for gastric pH measurements is non-invasive and affords more frequent testing. It would be useful in studying various conditions that may affect gastric pH.

Effects on Fatty Acid Metabolism of a New Powdered Human Milk Fortifier Containing Medium-Chain Triacylglycerols and Docosahexaenoic Acid in Preterm Infants.

Preterm infants require fortification of human milk (HM) with essential fatty acids (FA) to ensure adequate post-natal development. As part of a larger randomized controlled study, we investigated FA metabolism in a subset of 47 clinically stable preterm infants (birth weight ≤1500 g or gestational age ≤32 weeks). Infants were randomized to receive HM supplemented with either a new HM fortifier (nHMF; n = 26) containing 12.5 g medium-chain FA (MCFA), 958 mg linoleic acid (LA), 417 mg α-linolenic acid (ALA), and 157 mg docosahexaenoic acid (DHA) per 100 g of powder (in compliance with the latest guidelines) or a fat-free HMF (cHMF; n = 21). Plasma phospholipid (PL) and triacylglycerol (TAG), and red blood cell phosphatidylcholine (RBC-PC) and phosphatidylethanolamine (RBC-PE) FA profiles were assessed before and after 21 days of feeding. In the nHMF group, significantly increased levels of n-9 monounsaturated fatty acids were observed, formed most likely by elongation and desaturation of dietary saturated fatty acids present in HM. ALA fortification increased ALA assimilation into plasma TAG. Similarly, DHA fortification enriched the DHA content in RBC-PE, which, in this compartment, was not associated with lower arachidonic acid levels as observed in plasma TAG and phospholipids. RBC-PE, a reliable indicator of FA metabolism and accretion, was the most sensitive compartment in this study.

Choline and polyunsaturated fatty acids in preterm infants' maternal milk.

Choline, docosahexaenoic acid (DHA), and arachidonic acid (ARA) are essential to fetal development, particularly of the brain. These components are actively enriched in the fetus. Deprivation from placental supply may therefore result in impaired accretion in preterm infants. To determine choline, choline metabolites, DHA, and ARA in human breast milk (BM) of preterm infants compared to BM of term born infants. We collected expressed BM samples from 34 mothers (N=353; postnatal day 6-85), who had delivered 35 preterm infants undergoing neonatal intensive care (postmenstrual age 30weeks, range 25.4-32.0), and from mothers after term delivery (N=9; postnatal day 6-118). Target metabolites were analyzed using tandem mass spectrometry and gas chromatography and reported as medians and 25th/75th percentiles. In BM, choline was mainly present in the form of phosphocholine and glycerophosphocholine, followed by free choline, phosphatidylcholine, sphingomyelin, and lyso-phosphatidylcholine. In preterm infants' BM total choline ranged from 61 to 360mg/L (median: 158mg/L) and was decreased compared to term infants' BM (range 142-343mg/L; median: 258mg/L; p<0.01). ARA and DHA comprised 0.81 (range: 0.46-1.60) and 0.43 (0.15-2.42)% of total preterm BM lipids, whereas term BM values were 0.68 (0.52-0.88) and 0.35 (0.18-0.75)%, respectively. Concentrations of all target parameters decreased after birth, and frequently 150ml/kg/d BM did not meet the estimated fetal accretion rates. Following preterm delivery, BM choline concentrations are lower, whereas ARA and DHA levels are comparable versus term delivery. Based on these findings we suggest a combined supplementation of preterm infants' BM with choline, ARA and DHA combined to improve the nutritional status of preterm infants. This study was registered at www.clinicaltrials.gov. Identifier: NCT01773902.

Factors Determining Optimal Fatty Acid Absorption in Preterm Infants.

The aim of the present study was to quantify absorption coefficients of specific fatty acids in preterm infants as a function of diet, formula or breast milk (BM), and postnatal age; to identify the fatty acid structural characteristics that determine optimal fatty acid absorption. Fatty acids from dietary and fecal samples were extracted and quantified by gas chromatography-mass spectroscopy. Fatty acid absorption coefficients (FA-CFAs) were calculated by comparing the total amount of fatty acids supplied by the diet to the amount quantified in the total fecal output during a 3-day period. A total of 18 infants (BM 8, formula 10) were studied at 2 weeks of age, and 20 infants (BM 10, formula 10) were studied at 6 weeks of age. FA-CFAs decreased with increasing carbon length in formula-fed infants at 2 and 6 weeks. Results were similar but less in magnitude in BM-fed infants at 2 weeks with no difference at 6 weeks. Preterm infants fed formula demonstrated lower FA-CFAs as a function of increasing carbon length. This is consistent with limited pancreatic lipase production and with lipase being present in BM but not in formula. The fact that this pattern was seen in BM-fed infants at 2 weeks but not 6 weeks of age suggests that intestinal immaturity may also play a role in impaired fatty acid absorption. These data highlight principles that need to be considered to optimize delivery and absorption of dietary long-chain polyunsaturated fatty acids in preterm infants.

Early versus late administration of amino acids in preterm infants receiving parenteral nutrition.

Observational studies in preterm newborns suggest that delay in administering amino acids could result in a protein catabolic state and could impact on growth and development. To determine the effect of early administration of amino acids in premature newborns on growth, neurodevelopmental outcome, mortality and clinically important side effects. The standard search strategy of the Neonatal Review Group as outlined in The Cochrane Library was used. Relevant randomised controlled trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2012 I ssue 9 ), MEDLINE, EMBASE and CINAHL from their earliest dates to September 2012. The trial registry portal of the World Health Organization's International Cilinical Trial Registry Platform and ClinicalTrials.gov (US National Institute of Health) was searched to identify ongoing and completed but unpublished studies. Randomised controlled trials comparing early administration of amino acids with late administration in premature newborn infants were included. Early administration of amino acid solution was defined as the administration of amino acids in isolation or with total parenteral nutrition within the first 24 hours of birth; late initiation was defined as the administration of amino acids in isolation or with total parenteral nutrition after the first 24 hours of birth. The primary outcome measures were growth, neurodevelopmental outcome and mortality at 28 days. The secondary outcomes were biochemical abnormalities, sepsis and mortality. Both review authors independently selected trials, assessed trial quality and extracted data from the included studies. We contacted authors for further information. Fixed-effect analyses were performed. The treatment effect was expressed as mean difference for continuous variables and as risk difference and risk ratio for dichotomous variables. All results included 95% confidence intervals (CIs). Seven randomised controlled trials were included in this review. One randomised controlled trial reported no difference in crown-heel length and occipitofrontal head circumference by day 10. Four trials that enrolled 93 premature infants showed positive nitrogen balance (The mean difference with 95% CI was 250.42 (224.91 to 275.93 P value < 0.00001). Four trials showed a significant difference in the level of blood urea nitrogen (BUN) in the first 48 hours (P value < 0.00001). Early administration of amino acids did not result in metabolic acidosis in the first 24 hours. There is no available evidence of the benefits of early administration of amino acids on mortality, early and late growth and neurodevelopment. There is evidence from four randomised controlled trials included in this review that early administration of amino acids is associated with a positive nitrogen balance. The clinical relevance of this finding is not known. Acid-base status and ammonia levels were normal in the infants who received amino acids early. Given the small number of infants in the randomised controlled trials included in this review, the clinical heterogeneity among them, and the lack of data on important clinical outcomes, there is insufficient evidence to guide practice regarding the early versus late administration of amino acids to infants less than 37 weeks gestation.

Reduced Plasma Citrulline Levels in Low Birth Weight Infants With Necrotizing Enterocolitis

Citrulline, a nonprotein amino acid, is an intermediate of the urea cycle and synthesized in small intestine. Lower plasma citrulline levels were associated with reduced function of enterocytes. Necrotizing enterocolitis (NEC) causes high morbidity and mortality, and leads impaired intestinal functions. Plasma citrulline levels of neonates with a gestational age <32 weeks and ≤1,500 gm who developed NEC stage II/III were measured by high-performance liquid chromatography. We enrolled 36 preterm infants including 20 with NEC and 16 controls. Median citrulline levels of NEC and control groups were 8.6 and 20.18 μmol/l (P < 0.05), and cut off level of citrulline was 13.15 μmol/l with a sensitivity of 80% and a specificity of 82%. Median arginine levels of NEC and control groups were 22.02 and 39.89 μmol/l (P < 0.05), and cut off level of arginine was 28.52 μmol/l with a sensitivity of 70% and a specificity of 75%. Blood sampling day, gender, parenteral, and enteral nutrition did not affect the amino acid levels. We found lower plasma citrulline and arginine levels in preterm infants with NEC. Further studies are needed to determine most appropriate levels to predict recovery and prognosis of NEC, and treatment options with these amino acids in preterm infants.

Cyst(e)ine Requirements in Enterally Fed Very Low Birth Weight Preterm Infants

Optimal nutrition is of utmost importance for the preterm infant's later health and developmental outcome. Amino acid requirements for preterm infants differ from those for term and older infants, because growth rates differ. Some nonessential amino acids, however, cannot be sufficiently synthesized endogenously. Cyst(e)ine is supposed to be such a conditionally essential amino acid in preterm infants. The objective of this study was to determine, at 32 and 35 weeks' postmenstrual age, cyst(e)ine requirements in fully enterally fed very low birth weight preterm infants with gestational ages of <29 weeks. Infants were randomly assigned to 1 of the 5 graded cystine test diets that contained generous amounts of methionine. Cyst(e)ine requirement was determined with the indicator amino acid oxidation technique ([1-(13)C]phenylalanine) after 24-hour adaptation. Fractional [1-(13)C]phenylalanine oxidation was established in 47 very low birth weight preterm infants (mean gestational age: 28 weeks +/- 1 week SD; birth weight: 1.07 kg +/- 0.21 kg SD). Increase in dietary cyst(e)ine intake did not result in a decrease in fractional [1-(13)C]phenylalanine oxidation. These data do not support the hypothesis that endogenous cyst(e)ine synthesis is limited in very low birth weight preterm infants with gestational ages of <29 weeks, both at 32 and 35 weeks postmenstrual age. It is safe to conclude that cyst(e)ine requirement is <18 mg/kg per day in enterally fed very low birth weight preterm infants who are older than 32 weeks' postmenstrual age and whose methionine intake is adequate. Therefore, cyst(e)ine is probably not a conditionally essential amino acid in these infants.

Cysteine: a conditionally essential amino acid in low-birth-weight preterm infants?

Background: Cyst(e)ine can be synthesized de novo from methionine and serine and is, therefore, a nonessential amino acid in human adults. Several studies have suggested that cyst(e)ine might be a conditionally essential amino acid in preterm infants because of biochemical immaturity. No data are available on cyst(e)ine requirements in low-birth-weight (LBW) preterm infants.Objective: The aim was to determine cyst(e)ine requirements in LBW infants with gestational ages from 32 to 34 wk, measured 1 mo after birth with the use of the indicator amino acid oxidation technique.Design: LBW infants were randomly assigned to 1 or 2 of the 5 formulas containing graded cystine concentrations (11, 22, 32, 43, or 65 mg cyst(e)ine/100 mL) and generous amounts of methionine. After 24-h adaptation, cyst(e)ine requirement was determined by 13CO2 release from [1-13C]phenylalanine in expired breath. 13CO2 enrichment was measured by isotopic ratio mass spectrometry.Results: Cyst(e)ine requirement was determined in 25 LBW infants with a mean (±SD) gestational age of 33 ± 1 wk and birth weight of 1.78 ± 0.32 kg. Fractional oxidation of [1-13C]phenylalanine did not differ between the 5 groups.Conclusions: There is no evidence for limited endogenous cyst(e)ine synthesis in 4-wk-old LBW preterm infants born at gestational ages from 32 to 34 wk. It is safe to conclude that the cyst(e)ine requirement is <18 mg · kg−1 · d−1 providing generous amounts of methionine and that cyst(e)ine is probably not a conditionally essential amino acid in fully enterally fed LBW preterm infants born at 32–34 wk.

Plasma amino acids in preterm infants fed different human milk diets from a human milk bank

Summary Background & aims The enzymatic immaturity of the amino acid metabolic pathways in preterm infants makes these children vulnerable to deficiencies or amino acid excess. The purposes of this study was to evaluate the plasma amino acid profile of preterm infants fed one of three diets, and then compare them to the reference standards for preterm infants. Methods Thirty low-birthweight preterm infants were randomly assigned to diets: unmodified banked human milk (n=10), banked human milk evaporated to 70% (n=10), and banked human milk fortified with a bovine whey protein hydrolysate (n=10). Amino acid concentrations were analyzed by high efficiency liquid chromatography. Results No significant statistical differences in the amino acid profiles were found across groups. With few exceptions (arginine and glutamic acid), plasma amino acid concentrations in the three groups were lower than or reached the minimum values of references found in the literature for preterm infants. Conclusions The diets utilized led to deficiencies in amino acids, relative to the reference standards. It can be concluded that the supplies of these nutrients were below the needs of the infants in all groups.

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

Protein hydrolysates have been introduced in preterm formulae, but it is not clear whether they are needed for the feeding of preterm infants. We designed a randomized, controlled trial to test the effects of a preterm formula with hydrolysed cow's milk proteins on short-term growth and urinary and plasma amino acids levels. Infants with a birthweight < or = 1750 g and gestational age < or = 34 wk fed a conventional preterm infant formula (formula B) or a hydrolysed formula (formula A). Weight was measured daily; length, head circumference, mid-arm circumference and total skinfold thickness were measured weekly. Blood and urine were analysed for amino acid concentrations at start, 14 and 28 d. Twenty-one infants met the criteria for randomization. The daily feeding volumes were: formula A 172.8 +/- 5.6 vs formula B 170.1 +/- 2.8 ml/kg/d. Infants fed with formula A showed slower weight gain (17.4 +/- 3.4 vs 20.5 +/- 3.3 g/kg/d; p = 0.045) and lower mean change in Z-scores for weight (-0.18 +/- 0.16 vs 0.00 +/- 0.09; p = 0.009) and for head circumference (-0.06 +/- 0.13 vs 0.06 +/- 0.13; p = 0.049). After 14 d, infants receiving formula A had statistically significant higher urinary levels of essential amino acids compared to infants receiving formula B. Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

151 Low Levels of Cystein are Associated with Increased Proinflamma-Tory Activity, Arterial Hypotension and Severe Intraventricular Hemorrhage in Preterm Infants

Background: Increased proinflammatory activity is associated with oxidative stress, hemodynamic impairment and tissue damage. Cystein is an essential amino acid in preterm infants and metabolized to glutathione which is one of the most important intracellular antioxidant systems. Plasma levels of isoprostane are considered a stable marker of oxidative stress. Aim: To evaluate if plasma levels of cystein and isoprostane at 6 h of age are associated with proinflammatory activity and with subsequent morbidity in preterm infants.Methods: A two year prospective cohort study including inborn infants delivered at < 32 +0 gestational weeks after antenatal informed consent and excluding infants with major anomalies. 74 infants were enrolled with a mean (SD) gestational age of 27.1 (1.9) weeks. Blood sampling for analysis of proinflammatory (TNFá, IL-1 â, IL-2, IL-6, IL-8, IL-12, IFN- ã) and modulatory (IL-4, IL-10) cytokines was performed from umbilical cord and at 6 h postnatal age. Plasma levels of cystein and isoprostane were determined at 6 h postnatal age. Continuous invasive measurement of arterial blood pressure (ABP) was digitally stored during the first 72 h. Ultrasound examinations of the brain were performed at day 1, 3 and 7, at 6 weeks and at term age.Results: Levels of cystein in plasma at 6 h of age were positively related to gestational age at birth (r=0.46, p=0.001). Increased levels of IFN-ã, TNFá, IL-1â, IL-6 and IL-12 at 6 h were associated with a decrease in level of cystein (r=−0.37, p=0.002; r= -0.25, p=0.04; r=−0.45, p=0.000; r=−0.29, p=0.02 and r=−0.28, p=0.02 respectively). Level of cystein at 6h was positively related to average of mean ABP (0– 6 h), r=0.38, p=0.004. Decreased levels of cystein at 6 h were associated with development of severe IVH (grade III + IV), OR (95 % CI) 0.93 (0.88– 0.97), p=0.000. All associations remained significant after adjustment for gestational age and gender. Levels of isoprostane at 6 h were neither associated with cytokine levels in umbilical cord nor with those at 6h of age.Conclusion: Increased proinflammatory activity, arterial hypotension and development of severe IVH are associated with low levels of cystein early after birth in preterm infants.

P0111 PP QUANTITATIVE DETERMINATION OF TOTAL GLUTAMINE CONTENT IN BREAST MILK

Introduction: Glutamine (Gln) may be a conditionally indispensable amino acid in pre-term infants with low birth weight. Moreover, in term infants an adequate Gln supply is necessary for an optimal development of gut integrity and function. Knowledge of total Gln content (free and protein bound) of breast milk is thus of utmost importance. Respective data are, however, lacking due to methodological problems (instability of Gln during acid hydrolysis). The aim of the present study was, thus, to develop a new methodology enabling quantitative analysis of total Gln in human breast milk. Methods: Breast milk was harvested in 16 healthy women at days 4–7 (immature milk, IM) and 29–34 (mature milk, MM) after term delivery (>37 gestational weeks). Samples (2–3 mL gained 5 min after beginning of feeding) were immediately stored at −70 °C until analysis. Protein bound Gln: After removal of interfering fat and carbohydrates (extraction/dialysis) bound Gln was converted to acid stable diaminobutyric acid (DABA) by treatment with excess bis(1,1-trifluoroacetoxy)iodobenzene (BTI) for 4h at 50 °C. After evaporation, samples were hydrolyzed using microwave technology using boiling HCl. Liberated DABA was determined by HPLC with precolumn derivatization and fluorescence detection. Free Gln: After protein precipitation, Gln was determined in the supernatant by HPLC. Protein content was measured using a photometric assay. Precision and accuracy of the BTI method was confirmed by analysis of a standard oligopeptide with known Gln content. Results are presented as means ± SD. Results: The new BTI method enabled reliable analyses of bound Gln (CV: <5%) in breast milk proteins (IM: 6.1 ± 1.1 g; MM: 6.4 ± 1.3 g/100 g protein; NS, t-test). Free Gln concentrations were higher in MM (296 ± 205 μmol/L) compared with IM (143 ± 108 μmol/L, p=0.002). Considering the average protein content of IM (1.4 g/100 mL) and MM (1.0 g/100 mL), total Gln content in IM was 6.2 ± 1.4 mmol/L (0.9 ± 0.2 g/L) and in MM 4.6 ± 1.1 mmol/L (0.7 ± 0.2 g/L; p<0.001). Conclusion: The new method developed allowed for the first time a reliable quantification of total Gln content of breast milk. These data now allow calculation of Gln intake during breastfeeding (ca. 0.2 g/kg and day) and can be used to optimize nutrition strategies in infants requiring complementary feeding.