Figure 4.

Lipid 654 expression is lower in the serum of MS patients versus Alzheimer's patients. Frozen banked serum samples from MS and Alzheimer's patients were obtained from the UCLA Human Brain and Spinal Fluid Resource Center. Total serum lipids were derived and analyzed using MRM-mass spectrometry to identify and quantify the absolute ion abundance of Lipid 654 using three transitions of Lipid 654 (Transitions 1, 2 and 3, as in Figure 2). As in Figure 3, a defined quantity of ¹³C-labeled total lipids derived from P. gingivalis was added to each sample and used to adjust each value based on the efficiency of the analysis of that sample. Ion abundance is expressed as 10⁵. MS patients, N=13; Alzheimer's patients, N=15. Means: Transition 1, MS patients 112 139; Alzheimer's patients 1 297 909; Transition 2, MS patients 26 333; Alzheimer's patients 295 680; Transition 3: MS patients 13 786; Alzheimer's patients 142 076. Wilcoxon's rank-sum test was used to determine statistical significance.