Wernerman J, von der Decken A, Vinnars E
Metabolism. 1986 May;35(5):447-51. doi: 10.1016/0026-0495(86)90136-8.
Posttraumatic and septic states cause a loss of body proteins resulting in a negative nitrogen balance. The major part of the excreted nitrogen is derived from the proteins of skeletal muscle. The loss in proteins is due to a decrease in protein synthesis rather than an increase in protein degradation. Nutritional support may increase protein synthesis, and determination of its activity in skeletal muscle will give information on the utilization of nutrients in catabolic patients. The effect of nutritional support on healthy subjects was studied to achieve a background for future clinical studies. Male volunteers between 20 and 40 years old were refed parenterally or enterally after three days of starvation. Muscle biopsies (50 mg) were analyzed for the size distribution of ribosomes in a sucrose density gradient, and the ribosome concentration was determined per mg of DNA. Changes in the percentage content of polyribosomes preceded those of the total ribosome concentration. The total polyribosome concentration per gram wet weight of skeletal muscle decreased significantly during starvation. After one and two days of refeeding, a significant increase was observed, but the original level of the nonstarved subjects was not reached. The total ribosome concentration increased upon refeeding, but was not significantly different from that of the starved condition. The nitrogen balance was negative during starvation but attained equilibrium after two days of refeeding. Nutrition administered by the parenteral or enteral route were equally effective in restoring protein synthesis.
创伤和脓毒症状态会导致机体蛋白质流失，从而造成负氮平衡。排泄出的氮主要来源于骨骼肌蛋白质。蛋白质流失是由于蛋白质合成减少而非蛋白质降解增加所致。营养支持可能会增加蛋白质合成，测定其在骨骼肌中的活性将为了解分解代谢患者的营养物质利用情况提供信息。为了为未来的临床研究提供背景，对营养支持对健康受试者的影响进行了研究。20至40岁的男性志愿者在饥饿三天后接受肠外或肠内再喂养。对肌肉活检样本（50毫克）进行分析，以确定蔗糖密度梯度中核糖体的大小分布，并测定每毫克DNA中的核糖体浓度。多核糖体百分比含量的变化先于总核糖体浓度的变化。饥饿期间，骨骼肌每克湿重的总多核糖体浓度显著下降。再喂养一天和两天后，观察到显著增加，但未达到未饥饿受试者的原始水平。再喂养后总核糖体浓度增加，但与饥饿状态下的浓度无显著差异。饥饿期间氮平衡为负，但再喂养两天后达到平衡。肠外或肠内途径给予的营养在恢复蛋白质合成方面同样有效。
