Malondialdehyde alteration of low density lipoproteins leads to cholesteryl ester accumulation in human monocyte-macrophages |
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| Authors: | Alan M. Fogelman Ishaiahu Shechter Janet Seager Martha Hokom John S. Child Peter A. Edwards |
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| Affiliation: | Department of Medicine, Division of Cardiology, University of California at Los Angeles, School of Medicine, Los Angeles, California 90024 |
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| Abstract: | Glutaraldehyde treatment of 125I-labeled low density lipoprotein (125I-native-LDL) produced a modified LDL (125I-glut-LDL) with a molecular weight of 10 × 106 or more. Malondialdehyde treatment of 125I-native-LDL produced a product (125I-MDA-LDL) with a molecular weight not appreciably different from that of the original lipoprotein. However, the electrophoretic mobility of MDA-LDL indicated a more negative charge than native-LDL. 125I-MDA-LDL was degraded by two processes: a high-affinity saturable process with maximal velocity at 10-15 μg of protein per ml and a slower, nonsaturable process. The degradation of 125I-MDA-LDL was readily inhibited by increasing concentrations of nonradioactive MDA-LDL but was not inhibited by acetylated LDL or native-LDL even at concentrations as high as 1600 μg of protein per ml. After exposure of native-LDL to blood platelet aggregation and release in vitro, 1.73 ± 0.19 nmol of malondialdehyde per mg of LDL protein was bound to the platelet-modified-LDL. No detectable malondialdehyde was recovered from native-LDL that had been treated identically except that the platelets were omitted from the reaction mixture. |
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