title: The effects of surgery on the nitrogen metabolism of parenterally fed human neonates.
abstract: Nitrogen retention and rates of whole body amino nitrogen flux, protein synthesis, and breakdown were measured in 18 neonates during the 72 h immediately postsurgery. The infants were all intravenously fed with a crystalline amino acid source (Vamin), glucose, and Intralipid The infants were divided into two groups based on amino acid intake: either 2.3 SD 0.4 g or 3.9 SD 0.5 g/kg/day. Nonprotein energy intakes were similar and averaged 81 kcal/kg/day. Group A (n = 11) retained 145 SD 110 mg N/kg/day, whilst group B (n = 7) retained 315 SD 93 mg N/kg/day (p less than 0.001). There were no differences seen in flux, synthesis or breakdown. However, group B had significantly higher net protein synthesis rates (synthesis-breakdown) (p less than 0.01). The improved nitrogen utilization in group B was achieved principally by a reduction in endogenous protein breakdown. There were no differences between the two groups in urinary creatinine or 3-methylhistidine excretion. Since these two parameters reflect skeletal muscle turnover the differences between groups in nitrogen retention and turnover appear to be mediated through visceral protein.
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use*; D003404:Creatinine / Q000652:urine; D004573:Electrolytes; D002149:Energy Intake; D005947:Glucose; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007263:Infusions, Parenteral; D008762:Methylhistidines / Q000652:urine; D009584:Nitrogen / Q000378:metabolism*; D057947:Parenteral Nutrition Solutions; D011184:Postoperative Period; D014176:Protein Biosynthesis; D011897:Random Allocation; D012996:Solutions; D013514:Surgical Procedures, Operative
chemical_list: D000596:Amino Acids; D004573:Electrolytes; D008762:Methylhistidines; D057947:Parenteral Nutrition Solutions; D012996:Solutions; C545824:amino-acid, glucose, and electrolyte solution; D003404:Creatinine; D005947:Glucose; C028118:3-methylhistidine; D009584:Nitrogen