Regulation of Protein Synthesis in Neonatal Sepsis

描述（由申请人提供）： 新生儿在疾病期间对营养消耗的敏感性，以及其有效利用营养物质促进生长的相反代谢能力，为评估脓毒症期间营养素-激素相互作用提供了一种新的范式。我们的长期目标是确定调节氨基酸使用的基本机制，包括激素，营养素和发育的相互作用，在炎症条件下，如败血症。在这个建议中，我们打算分析败血症新生儿氨基酸代谢的调节途径。在目的1中，我们假设提高内毒素血症新生儿的氨基酸水平可以提高肌肉蛋白质合成率。 因此，将通过使用酶-底物钳夹技术和同位素示踪法体内测量蛋白质合成，在内毒素（LPS）输注的7天和26日龄猪中进行氨基酸剂量反应研究。在目的2中，我们希望确定氨基酸是否影响LPS灌注的肌肉蛋白质合成， 新生儿通过影响参与mRNA结合的翻译起始因子的激活，但不是met-tRNAi，40 S核糖体复合物。因此，我们将在肌肉中测量真核起始因子（eIF）2 B活性、eIF 4 E、4 E-BP 1、p70 S6激酶和蛋白激酶B（PKB）的磷酸化、eIF 4 E与eIF 4 G和4 E-BP 1的结合以及NF κ B信号传导的活化。在目标3中，我们希望确定新生儿败血症是否会增强肌肉蛋白水解，以及胰岛素是否可以抑制蛋白水解速率。因此，将使用稳定同位素示踪剂/质量跨器官平衡技术检查接受LPS输注的7日龄和26日龄猪（进行底物钳夹），以定量不同浓度胰岛素存在下后肢中的蛋白质降解。了解危重疾病期间营养素-激素界面及其发育特征，有助于描述和优化婴儿和儿童急性疾病后恢复和重建适当生长的医疗管理。

DESCRIPTION (provided by applicant): The susceptibility of the neonate for nutritional depletion during illness, and its opposed metabolic ability to utilize nutrients efficiently for growth offers a novel paradigm to evaluate nutrient-hormonal interactions during sepsis. Our long-term objectives are to identify the fundamental mechanisms that regulate amino acid use, including the interaction of hormones, nutrients, and development, in inflammatory conditions such as sepsis. In this proposal, we intend to analyze the pathways that regulate amino acid metabolism in septic neonates. In Aim 1, we hypothesize that raising amino acids in endotoxemic neonates enhances muscle protein synthesis rates. Thus, amino acid dose response studies will be performed in endotoxin (LPS) infused 7- and 26-day-old pigs by using hormone-substrate clamp techniques and in vivo measurement of protein synthesis with isotopic tracer methods. In Aim 2, we wish to determine whether amino acids influence muscle protein synthesis in LPS-infused neonates by affecting activation of translation initiation factors involved in the binding of mRNA, but not met-tRNAi, to the 40S ribosomal complex. Consequently, we will measure in muscle eukaryotic initiation factor (elF) 2B activity, the phosphorylation of eIF4E, 4E-BP1, p70S6 kinase and protein kinase B (PKB), the association of eIF4E with eIF4G and 4E-BP1, and the activation of NFkappaB signaling. In Aim 3, we wish to determine whether muscle proteolysis is enhanced by sepsis in neonates and whether the rate of proteolysis can be suppressed by administration of insulin. Therefore, LPS-infused 7- and 26-day-old pigs subjected to hormone-substrate clamps will be examined using a stable isotopic tracer/mass transorgan balance technique to quantify protein degradation in the hindlimb in the presence of different concentrations of insulin. Knowledge of the nutrient-hormone interface during a critical illness and their developmental distinctiveness can help characterize and optimize the medical management towards recovery and reestablishment of adequate growth after infants and children have been acutely ill.