An enzyme combination assay for serum sphingomyelin: Improved specificity through avoiding the interference with lysophosphatidylcholine.

Serum sphingomyelin (SM) has predictive value in the development of atherosclerosis. Furthermore, SM plays important roles in cell membrane structure, signal transduction pathways, and lipid raft formation. A convenient enzymatic method for SM is available for routine laboratory practice, but the enzyme specificity is not sufficient because of nonspecific reactions with lysophosphatidylcholine (LPC).

Remnant lipoprotein cholesterol homogenous assay (RemL-C) is closely associated with very-low-density lipoprotein remnants: comparison with the immunoseparation assay.

Background: Remnant-like particle-cholesterol (RLP-C) is recognized as a risk factor for cardiovascular disease. As an alternative to the immunoseparation assay widely used for the measurement of RLP-C, a new remnant lipoprotein-C homogenous assay (RemL-C) is available. In light of its homogeneity as an assay method, we speculated that this homogeneous assay (RemL-C) is closely associated with very-low-density lipoprotein(VLDL) remnant including intermediate-density lipoprotein(IDL).

Development of a homogeneous assay to measure remnant lipoprotein cholesterol.

Background: Quantification of triglyceride-rich lipoprotein (TRL) remnants is useful for risk assessment of coronary artery disease and the diagnosis of type III hyperlipoproteinemia. Although an immunoseparation procedure for remnant-like particle cholesterol has been evaluated extensively in recent years, available methods for measuring TRL remnants have not achieved wide use in routine laboratory practice, suggesting a need for a homogeneous assay that can measure TRL remnant cholesterol in serum or plasma without pretreatment.

Methods: We screened for suitable surfactants that exhibited favorable selectivity toward the VLDL remnant (VLDLR) fraction, including intermediate-density lipoproteins (IDLs).