Fig. 3.

Recovery of Lipid 654 in lipid extracts of carotid endarterectomy samples or carotid artery samples from young individuals. Carotid endarterectomy samples (Atheromas, n = 10) were recovered at the time of surgical excision; a portion of each endarterectomy sample was removed for pathological evaluation and the remainder of the sample was frozen until processing. Arteries from young adults (Cont Art, n = 6) were recovered at necropsy and fresh frozen as processed at the National Disease Research Interchange. Frozen samples were thawed and minced into small pieces. The samples were extracted for 3 days in organic solvent according to the procedure of Bligh and Dyer and the recovered lipids were dried under a stream of nitrogen. The recovered lipids were dissolved in chloroform and 1 mg was aliquoted and was supplemented with D₉-Lipid 654 internal standard (0.2 ng/mg total lipid). Samples were then dissolved in 500 μl of HPLC solvent and analyzed by MRM-MS, as described in the Materials and Methods. An autosampler was used for sample introduction to the mass spectrometer and each sample was followed by a solvent wash to ensure negligible lipid carryover between samples. Each P value was determined using the Mann-Whitney U test. A: Comparison of the Lipid 654 levels versus total lipid (in nanograms per milligram). B: Comparison of Lipid 430/Lipid 654 ratios in the same artery lipid extracts.