Dynamic Changes Of Blood Amino Acid And Acylcarnitine Levels In Neonatal Nutritional Support

Part ?: A retrospective analysis of blood amino acid profiles in neonates during hospitalizationObjective: To compare the differences of blood amino acids profiles between preterm infants and full-term infants,and between small for gestational age(SGA)infants and appropriate for gestational age(AGA)infants;to realize the relationship between nutritional stages and blood amino acid concentration,and between intake of amino acid or protein and level of amino acid in blood;and to provide basis for neonatal nutrition from the perspective of metabolism.Methods: Neonates hospitalized from January 2012 to December 2016 were involved in the retrospective investigation.(1)According to gestational age,the neonates were divided into premature infants group and term infants group,and the blood amino acid profiles between the two groups were compared by using independent-samples t-test.(2)According to the relationship between birth weight and gestational age,the neonates were divided into SGA and AGA group,then the differences between them were compared by using independent-samples t-test.(3)According to the nutritional intervention before sampling,the neonates were divided into different groups of nutritional stages,and the differences of amino acid levels among the groups were compared by ANOVA and covariance analysis.(4)The correlation between intake of amino acid or protein and blood amino acid levels was explored by using partial correlation analysis.Results: A total of 350 neonates were enrolled in the study.(1)Blood levels of essential and conditionally essential amino acids in preterm infants were significantly higher than those in term infants.Tyrosine level was significantly different at each nutritional stage,however,the differences of other amino acid levels were statistically significant only within specific nutritional stages.(2)The concentrations of alanine and tyrosine was significantly lower in SGA group than those of AGA group.(3)Most essential,conditionally essential and nonessential amino acids differ statistically among different groups of nutritional stages.(4)Blood levels of leucine,valine,threonine and serine were positively correlated with enteral protein intake and parenteral amino acid intake.Aspartic acid and arginine levels were separately correlated with enteral protein intake and parenteral amino acid intake.Conclusion:(1)The features of amino acid metabolism in preterm and term infants are different,but at the same nutritional stage,the status of amino acid metabolism is similar.(2)Alanine and tyrosine levels of SGA were lower than AGA,which may provide clues for biochemical markers of early metabolic changes.(3)Blood amino acid profile is influenced by nutritional stage.(4)A number of amino acid levels were correlated with intestinal protein intake or parenteral amino acid intake.Part ?: A prospective study on changes of blood amino acid and acylcarnitine profiles in preterm infants at different nutritional stagesObjective: To explore the dynamic changes of amino acid and acylcarnitine profiles in preterm infants of different gestational age at different nutritional stages,including before nutritional support,total parenteral nutrition,partial parenteral nutrition and total enteral nutrition;to find the relationship between metabolism and nutritional support.Methods: Preterm infants hospitalized from January 2017 to December 2017 who needed parenteral nutrition support after birth were enrolled into the study and be divided into extremely preterm infants,very preterm infants,moderately preterm infants and late preterm infants.The history of birth and mother's pregnancy were collected,and the nutritional interventions were recorded.Blood samples were collected by dried blood spot before parenteral nutrition,at total parenteral nutrition stage,partial parenteral nutrition stage and total enteral nutrition stage.The samples were analyzed by LC-MS/MS for the detection of amino acid and acylcarnitine concentrations.Kruskal-Wallis test,?2 test and ANOVA were used to compare nutritional status and growth situation of preterm infants of different gestational ages,as well as blood levels of amino acid and acylcarnitine at different nutritional stages and gestational ages.Results: A total of 124 premature infants were enrolled.(1)The duration of parenteral nutrition in preterm infants vary with the gestational ages.Physical growth during hospitalization of preterm infants was generally lower than the reference standard.(2)Most of the amino acid and acylcarnitine levels were significantly different at different nutritional stages.A number of amino acids and acylcarnitines were significantly different in the transition from parenteral nutrition to enteral nutrition.The levels of threonine and aspartic acid gradually increase along with the nutritional stages,but the levels of valine,methionine and phenylalanine show a gradually decreasing trend.(3)The amino acid and acylcarnitine profiles were significantly different at the stage of partial parenteral nutrition,but similar at the other nutritional stages.Conclusion: The levels of amino acids and acylcarnitines in preterm infants vary with the nutritional stages.The profiles of amino acids and acylcarnitines in preterm infants of different gestational ages are significantly different,especially at the stage of partial parenteral nutrition.