The broad, and long-term objective is to have the lipoprotein particle density profile be part of an individual's risk assessment for cardiovascular disease (CVD). Lipoproteins are nanoparticles circulating in the blood that mediate lipid metabolism. They are divided into 3 major classes based on their densities:very-low density lipoprotein(VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL). The cholesterol content of LDL, (LDL-C) correlates positively with the risk of cardiovascular disease (CVD) while the cholesterol content of HDL, (HDL-C) is inversely related. Subclasses based on density are associated with increased risk of CVD. These include remnant lipoprotein, lipoprotein(a), dense LDL and dense HDL. An individual's lipoprotein particle density profile is a composite of relative risk factors linked to the development of arterial atherosclerosis. Density gradient ultracentrifugation (DGU) has long been considered to be the fundamental method for the characterization, isolation and quantitation of lipoproteins. It would also be the ideal method for measuring an individual's lipoprotein particle density profile in the assessment of relative risk for CVD. But, experimental problems associated with this method, since it was first used in this application a half-century ago, diminished its general utility in clinical chemical analysis. The tabletop very fast ultracentrifuge, introduced in the past decade, has transformed the analysis to microscale operation and analysis time from days to hours. However, difficulties in achieving high precision in sample preparation and the limited choices of density-gradient forming solutes (alkali halides, sugars) remain as problematic for the adoption of DGU for large-scale lipoprotein analysis. The """"""""perfect solute"""""""" would be one that can form a reproducible density gradient from a homogeneous solution in a high g-force environment and allow lipoprotein particles to focus at their densities in a short time frame. The novel feature of this proposal is the introduction of a new class of density-gradient forming solutes (metal ion complexes) that gives versatility at the molelcular structure level in influencing sedimentation and diffusion rates in the ultracentrifuge. The Cs+ salt of Bi(EDTA) has been chosen. Preliminary studies suggest that it may be the """"""""perfect solute"""""""".
The specific aims focus on fundamental studies using Cs(BiEDTA) to achieve the high accuracy and precision required for clinical applications in measuring the lipoprotein particle density profile. A second specific aim is to use this same profile to isolate nd quantitate cholesterol levels of LDL-C, and HDL-C and evaluate accuracy by comparision with CDC-methods. A third specific aim is to link DGU with immunoreactivity to identify apolipoprotein-specific components of the liprotein particle density profile. ? ?
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