1) Elevated whole body protein synthesis rates (PSR) are found in patients with tumors and in patients with hepatic dysfunction when 15N glycine is used as the tracer. Are the elevated PSR"s in cancer patients due to the addition of protein synthesis by the tumor to the protein synthesis by the rest of the body? Or are they secondary from the patient also having liver insufficiency. We plan to answer these questions by comparing the whole body PSR against the more reliable tissue fractional synthesis rates (FSR) in patients with tumors of the gastro-intestinal tract using 15N glycine and 13C leucine as tracers. 2) Is there any advantage in adding medium chain length fatty acids (MCFA's) to the TPN mixture given to patients who are septic and TPN intolerant? The hypothesis to be tested is that in severely septic patients long chain fatty acids (LCFA's) cannot be utilized optimally because of a metabolic block. MCFA's are metabolised somewhat differently and therefore may be able to bypass the postulated blockage. We plan to answer this question by comparing the effects of MCFA's on protein metabolism using first, septic rats and then septic patients. MCFA's will be considered beneficial if there is: (i), an increase in protein synthesis; (ii), a decrease in muscle protein breakdown; (iii), a decrease in the metabolic burden on the liver and (iv), normalization of the plasma amino acid pattern.