Objective Lecithin:cholesterol acyltransferase (LCAT) has been shown to play a role in the depletion of lipid oxidation products but this has so far not been studied in beta-Amyloid (1-11) human beings. individuals with mutations plasma LCAT activity HDL cholesterol apoA-I arachidonic acid and its oxidized derivatives oxidized phospholipids on apo(a)-comprising lipoproteins HDL-associated platelet-activating factor-acetylhydrolase activity and the antioxidative capacity of HDL were gene-dose-dependently decreased. Oxidized phospholipids on apoB-containing lipoproteins was improved in heterozygotes (17%; alleles. Summary Service providers of mutations present with significant reductions in LCAT beta-Amyloid (1-11) activity HDL cholesterol apoA-I platelet-activating factor-acetylhydrolase activity and antioxidative potential of HDL but this is not associated with guidelines of improved lipid peroxidation; we did not observe significant changes in the oxidation products of arachidonic acid and linoleic acid HAS3 immunoreactive oxidized phospholipids on apo(a)-comprising lipoproteins and IgM and IgG autoantibodies against malondialdehyde-low-density lipoprotein. These data show that plasma LCAT activity HDL-associated platelet-activating factor-acetylhydrolase activity and HDL cholesterol may not influence the levels of plasma lipid oxidation products. position of phosphatidylcholine (or lecithin) and transfers this fatty acid to free cholesterol forming a cholesteryl ester (CE). Through this reaction it generates most of the CE present in human plasma therefore maturing HDL.13-15 Through this phospholipase-A2 (PLA2) activity LCAT can also hydrolyze oxidized acyl chains from phosphatidylcholine-based OxPL generating the less bioactive lysophosphatidylcholine (lysoPC)7 and oxidized free fatty acids which may be subsequently used by LCAT to esterify diacylglycerol thereby generating triglycerides in addition to the formation of CEs.16 Several in vitro and animal studies have shown that through this PLA2 activity LCAT can apparently remodel vascular lipids resulting in an apparent decrease in oxidative pressure by hydrolyzing oxidized fatty acids from phosphatidylcholine-based OxPL.7 16 In humans mutations in resulting in a loss of enzymatic LCAT activity cause reductions of HDL-c levels.19 It is however not known what effect the loss of LCAT activity might have on lipid oxidation. To study this we used plasma beta-Amyloid (1-11) of service providers of 1 1 or 2 2 defective LCAT alleles and beta-Amyloid (1-11) of family settings to measure (1) the activity of enzymes that are founded modifying OxPL by removal of mutations were enrolled in this study. Nomenclature of the mutations is based on guidelines of the Human being Genome Variation Society (for LCAT this means that 24 aa positions-leader sequence-are added to previous annotations). Settings were 1st- second- or third-degree family members or spouses. Informed consent was acquired for blood sampling storage genetic and biochemical analysis. The study was authorized by the Institutional Review Table of the Academic Medical Center in Amsterdam. Plasma Lipids and LCAT Activity Serum and EDTA plasma blood samples were acquired after an over night fast and stored at -80° C until use. Total cholesterol low-density lipoprotein (LDL) cholesterol HDL-c triglycerides and apoA-I and apoB were measured using a COBAS MIRA analyzer. LCAT activity was measured in whole plasma using a proteoliposome substrate.23 Lipoprotein a (Lp(a)) was measured using quantitative immunoprecipitation analysis with commercially available antiserum (Diasorin Stillwater MN). Quantification of LysoPC Molecular Varieties Internal standard (1000 ng 19:0 Lyso-PC) was added to human being plasma and lipids were extracted 3× by a revised Dole extraction method.24 The combined organic extracts were dried under N2 flow and then the dried lipids resuspended in water/acetonitrile/2-propanol (8/1/1) and injected onto a Agilent C8 column beta-Amyloid (1-11) (2×150 mm 5 μm) for separation using Waters HPLC 2690. LysoPC molecular varieties were recognized using electrospray ionization in positive ion mode with multiple reaction monitoring using characteristic parent→child transitions for each species on a tandem beta-Amyloid (1-11) mass spectrometer (Micromass Quatrro Ultima.