Acute phase and transport protein synthesis in simulated infection in undernourished men using uniformly labelled Spirulina Platensis

Although it has been known for many years that injury and infection lead to body nitrogen loss, the reason has remained obscure. In this paper, we develop the argument that the processes that are activated during infection demand the provision of specific amino acids which have to be supplied from body protein. In particular, we show that the positive acute phase proteins are very rich in the aromatic amino acids and the exaggerated use of these amino acids (phenylalanine, tryptophan and tyrosine) in acute phase protein synthesis lead to an endogenous ''amino acid imbalance'' which restricts the use of other amino acids for tissue protein synthesis. Minimally invasive protocols, involving the administration of 15N and 13C-labelled amino acids for studying whole body nitrogen turnover, amino acid oxidation and plasma protein synthesis are described. (author). 22 refs, 3 tabs