Human plasma apolipoproteins continue to be isolated from normal controls and patients with dyslipoproteinemias utilizing a series of methodologies including gel permeation chromatography, ion exchange chromatography, FPLC, HPLC, and preparative isoelectrofocusing and SDS gel electrophoresis. Isolated apolipoproteins are used for structural analyses of apolipoproteins containing mutations isolated from patients with specific dyslipoproteinemias. In addition the apolipoproteins isolated from control and patients with dyslipoproteinemias are used to determine the lipoprotein and apolipoprotein metabolism in normal volunteers as a well as dyslipoproteinemic patients. ApoA-I and apoA-II, have been utilized to determine the metabolism of LpA-I and LpA-I:A-II in control subjects as well as patients with LCAT deficiency, Fish Eye Disease, apoA-I deficiency, and CETP deficiency. The combined results from these studies have demonstrated that LpA-I and LpA-I:A-II have different metabolic pathways and the concentration of these two HDL lipoprotein particles may be independently altered in different disease states. ApoA-I has been isolated from both mice and rabbits. The A-I apolipoproteins are being used in kinetic studies in mice and rabbits in the Branch in conjunction with the mouse and rabbit transgenic programs. ApoA-II has also been isolated from mice but is not present in rabbit plasma. Of particle interest has been the analysis of nascent HDL particles which have been proposed to be the most effective lipoprotein particles in removing cholesterol from peripheral cell. Nascent HDL particles have been separated by 2 dimensional gel electrophoresis and the individual lipoprotein particles identified by immunoblot analysis. We have identified two separate nascent HDL particles, pre-beta LpA-I and LpE which may play a critical role in reverse cholesterol transport. These two nascent particles are being analyzed in control subjects and patients with familial hypoalphalipoproteinemia with and without premature cardiovascular disease.
