The serum neuraminic acid distribution. I. Methodology.

Abstract

Abstract 1.1. The quantitative distribution of serum neuraminic acid between the albumin and globulin protein fractions, as separated by salt fractionation, was investigated for 37 normal subjects (26 adults and 11 children) and for 111 patients with neurologic and nonneurologic diseases using a modified diphenylamine colorimetric reaction. 2.2. Because of the previously reported increase of neuraminic acid-containing lipids (gangliosides) in the cerebral gray matter from cases of amaurotic family idiocy (A.F.I.), serum determinations on the 8 patients in this group were carried out at 6- to 8-week intervals for a total of 36 separate analyses. 3.3. For purposes of group statistical analysis, the 111 patients were divided into 5 disease categories and compared against the normal control group. The total serum neuraminic acid was found to be elevated in all the groups studied, with the highest mean values present in the nonneurologic, debilitating diseases, e.g., rheumatic fever, rheumatoid arthritis, malignant neoplasms, etc. 4.4. The best statistical indicator for differentiating A.F.I. from all other disease groups was the serum globulin neuraminic acid/total serum neuraminic acid ratio. That the increase in this ratio represents a relative shift of serum glycoproteins from the albumin to the globulin protein fractions was verified by means of starch block electrophoresis of both normal and A.F.I. sera. 5.5. The possible relationship between the markedly increased ganglioside content of the neurons of brain gray matter in A.F.I. and of the relative increase in serum glycoproteins (as determined by neuraminic acid content) associated with the alpha-2 and beta globulin fractions is discussed.