A KINETIC-STUDY OF L-2H3-METHYL-1-13C-METHIONINE IN PATIENTS WITH SEVERE BURN INJURY

To explore the consequences of severe burn injury on methionine metabo lism we carried out tracer studies, using 1-C-13, H-2(3)-methyl! meth ionine, given by continuous intravenous infusion, in 12 adult patients . Each was studied in the ''fasted'' and in the fed state while receiv ing parenteral nutrition. Compared with findings obtained in our previ ous studies in healthy adults using a similar protocol, the rates of t ransmethylation (Tm), homocysteine remethylation (Rm), and methionine oxidation (C) were all substantially increased in burn patients. From the relationships between these systems, it appears that there is a re lative increase in the recycling of methionine carbon via Rm during th e fasted state. This implies active methyl group transfer and utilizat ion in burn patients. Parenteral feeding increased methyl-methionine f lux (Qm) and the rates of Tm, Rm, and C. However, the Tm/Qm ratio did not change with feeding in the patients, whereas it increased in healt hy young adults. This may not necessarily reflect the consequences of burn injury, but may be due to differences in the route of methionine intake or its level relative to requirement, compared with the conditi ons of study in healthy adults. Further studies on methionine-cysteine interrelationships, using an isotopic approach, in burned patients ar e needed to evaluate these possibilities.