THE AMINO ACID CONTENT OF HUMAN CEREBROSPINAL FLUID IN NORMAL INDIVIDUALS AND IN MENTAL DEFECTIVES*

Abstract

Concentrations of amino acids were determined using the automatic amino acid analyzer in pooled normal human cerebrospinal fluid (CSF), and in individual fluid samples from patients having various genetically determined forms of mental deficiency. These concentrations have been compared with values obtained by other investigators using different techniques, as well as with the concentrations of amino acids in human postabdorptive plasma. Twenty-two amino acids were regularly present in CSF, and 3 others were sometimes present. Cystine and a-aminobutyric acid, which have been reported as constituents of CSF, were not detected. Seven unidentified ninhydrinpos-itive substances were regularly found in CSF, one of them in relatively large amounts. Except for greatly elevated concentrations of phenyl-alanine in the CSF of patients with phenylketonuria, the concentrations of amino acids in the CSF of the mental defectives studied did not differ significantly from those found in pooled normal CSF.