Intravenous nutrition and tumor host protein metabolism

Abstract

The difficulty of maintaining adequate nutritional status in cancer patients is well recognized [I, 181. Recently there has been considerable interest in the clinical use of intravenous diets to support these patients [2, 51. Although present evidence strongly suggests that the cancer patient receiving chemoor radiotherapy is significantly benefited by parenteral nutrition, there exists little information on the metabolic changes induced in tumor and host tissue by parenteral nutrition. Unfortunately, nitrogen balance studies are of little value in the cancer patient for they cannot distinguish between host and tumor utilization of nitrogen intake. The use of labeled amino acids has facilitated the measurement of protein synthesis in viva [3, 9, 151. This study involves the use of [15N]glycine as a nitrogen tracer to examine selective utilization of nutrients by host and tumor tissue. The effects of the presence of a tumor and an acute change in nutrient intake are investigated. We have previously reported preliminary data on protein synthetic rates of tumor host tissues [16]. The present study updates our findings on tissue protein synthesis rates and pursues the intracellular localization of the observed tissue changes.