NUTRITION AND AGING--PROTEIN AND ENERGY INTERACTIONS

衰老与身体蛋白质含量的逐渐减少有关， 主要是骨骼肌。维护身体的意义 蛋白质平衡得到了很好的认识，因为身体蛋白质的30%-50%的损失是 与生命不相容和蛋白质枯竭是导致 住院患者的发病率。最近的一次回顾分析 贝斯以色列医院入院时测定的血清白蛋白浓度 在医院65岁以上的患者中发现了显著的 低白蛋白水平与再次住院之间的关系(赫尔曼) 埃特。Al.)。因此，了解调节身体蛋白质的因素 新陈代谢，尤其是老年人的新陈代谢，具有相当大的生物学和 临床重要性。这项提议中要检验的假设是 在衰老过程中，能量和蛋白质代谢之间的相互作用 可能损害个人应对能力的方式的改变 成功应对生理性和病理性应激。研究将利用 稳定同位素示踪方法学、间接量热法和动静脉 平衡技术，探索全身和局部(骨骼肌和 青年(18-30岁)和老年人的能量和氨基酸(AA)代谢 (65岁以上)志愿者。该建议的具体目标是：(1) 确定静息代谢率(RMR)与 蛋白质周转率随年龄增长的变化及定量 骨骼肌对RMR和蛋白质周转差异的贡献 在旧的时代。(2)研究胰岛素和AA的可用性对 肌肉蛋白质周转、氧摄取及其相互作用的估计 两性关系。(3)检测老年人内脏AA代谢； 具体地说，为了确定是否存在年龄相关的差异， 特定肝脏蛋白(白蛋白和白蛋白)的合成分数 载脂蛋白B)。如果后者为真，次要的具体目标是 确定与年龄相关的能量消耗差异(EE)或 胰岛素敏感性可以解释这些变化。(4)确定 不同产能营养素的代谢结果，特别是 果糖和葡萄糖对EE和蛋白质/AA年龄相关差异的影响 新陈代谢。这些研究的完成将进一步加深我们对 影响人体蛋白质和能量状况的营养因素 身体成分变化对蛋白质完整性的影响 代谢和蛋白质-能量相互作用。获得的数据可能有助于 为成长中的老年人制定特定的饮食指南 人口的目标是将发病率和死亡率降至最低。

Aging is associated with a gradual reduction in body protein content, primarily skeletal muscle. The significance of the maintenance of body protein balance is well recognized since loss of 30-50% of body protein is incompatible with life and protein depletion is a major factor in the morbidity of hospitalized patients. A recent retrospective analysis of serum albumin concentrations measured on admission to the Beth Israel Hospital in patients over the age of 65 yrs revealed a significant association between low albumin levels and hospital readmissions (Herrmann et. al.). Therefore, understanding factors which regulate body protein metabolism, especially in the elderly, is of considerable biological and clinical importance. The hypothesis to be examined in this proposal is that during aging, the interactions between energy and protein metabolism change in ways that may compromise the individual's ability to respond "successfully" to physiologic and pathologic stress. Studies will utilize stable isotope tracer methodology, indirect calorimetry, and arteriovenous balance techniques to explore whole body and regional (skeletal muscle and liver) energy and amino acid (AA) metabolism in young (18-30 years) and old (65+ years) volunteers. The specific aims of the proposal are: (1) To determine whether the relationship between resting metabolic rate (RMR) and protein turnover change with advancing age and to quantitate the contribution of skeletal muscle to differences in RMR and protein turnover in the old. (2) To examine the effect of insulin and AA availability on estimates of muscle protein turnover, O2 uptake and their inter- relationships. (3) To examine splanchnic AA metabolism in the aged; specifically, to determine whether there is an age-associated difference in fractional synthesis rates of specific hepatic proteins (albumin and apoprotein B). If the latter is true, a secondary specific aim is to determine whether age-related differences in energy expenditure (EE) or insulin sensitivity could account for these changes. (4) To determine the metabolic consequences of different energy-yielding nutrients, specifically fructose and glucose, on age-related differences in EE and protein/AA metabolism. Completion of these studies will further our understanding of nutritional factors which influence body protein and energy status and of the impact of body compositional changes in the integrity of protein metabolism and protein-energy interactions. Data obtained may aid in the development of specific dietary guidelines for the growing elderly population directed at minimizing morbidity and mortality.