Amino acids and thiobarbituric acid reactive substances in cerebrospinal fluid and plasma of patients with septic encephalopathy.

Amino acids and thiobarbituric acid reactive substances (TBARs) in the cerebrospinal fluid (CSF) and plasma were identified and assayed in 5 patients with septic encephalopathy. Levels of all the high molecular weight neutral amino acids (LNAAs) appeared to increase in the CSF. CSF levels of phenylalanine (PHE) and methionine (MET) increased significantly by factors of 20.9 and 9.5, respectively, and the plasma PHE level increased 7.5-fold. No significant changes in branched-chain amino acids were observed in either the CSF or plasma. The CSF/plasma ratios of valine (VAL), tyrosine (TYR), PHE, and MET significantly increased to 0.21, 0.46, 0.52, and 0.52, respectively. TBAR levels increased 4-fold in the CSF and also were slightly increased in the plasma, suggesting that lipid peroxidation in the central nervous tissues is markedly increased. We conclude that increases in LNAA levels and in lipid peroxidation in the central nervous tissues may play important roles in the development of septic encephalopathy.