Sawada N, Obama T, Koba S, et al. - Given that oxidized low-density lipoprotein (oxLDL) represents a recognized risk factor for atherogenesis, researchers focused on structural characteristics of oxLDL present in human circulation associated with atherosclerosis. In flow-through and electronegative LDL (LDL(-)) fractions, on fractionation of LDL on an anion-exchange column, experts noted that in vivo-oxLDL, identified by the anti-oxidized phosphatidylcholine (oxPC) monoclonal antibody, was recovered. In patients with acute myocardial infarction vs healthy people, the presence of three-fold higher amount of the electronegative in vivo-oxLDL, namely oxLDL in LDL(-) fraction, was detected. Surprisingly, LDL(-) fraction comprised apoA1 in addition to apoB, and HDL-sized particles were identified with transmission electron microscopy. Most of the PC species was identified to be not oxidized, whereas oxPC and lysoPC did not accumulate. As proposed by the experts, human circulating plasma contains two types of in vivo-oxLDL and the electronegative in vivo-oxLDL accompanies oxidized HDL.