13C-Leucine-Tracer-Technique in clinical research on postoperative protein metabolism

Abstract

The non-invasive 13C-Leucine Infusion-Technique allows quantitative infonnation about protein decarb-oxylation as well as the dynamics of the protein metabolism like protein synthesis, protein oxidation, protein degradation and protein retention. In clinical research it is possible to compare the quality of different nutrition regimen with regard to protein-sparing effects by this method without irritation of the patient and without interrupting his nutrition. Two clinical investigations had been perfonned at the Surgical University Clinic Mannheim to study postoperative protein metabolism: 1. on the influence of different carbohydrates (Xylitol/Glucose) concerning postoperative protein metabolism during a hypocaloric nutrition regimen and 2. on the course of the individual postoperative protein metabolism during different phases after the operation and in comparison of two requirement-adapted nutrition regimen. Results 1. Our first study showed no influence of the applied carbohydrate (Xylitol or Glucose) to the postopera-tive protein metabolism. 2. The comparison of a peripheral-venous nutrition regimen composed of maltose (12%), amino acid solution (7%) and fat (20%) (2,000 kcal, 650 mosm/l) with a central-venous nutrition regimen composed of glucose/laevulose/xylitol (40%) and amino acid solution (7%) (2,000 kcal, >2,000 mosm/l) showed no changes in postoperative protein metabolism. Contrary to the accumulated nitrogen balance the 13C-Leucine-Tracer-Technique showed still a light catabolism even on the fifth day after operation.