title: Development of a homogeneous assay to measure remnant lipoprotein cholesterol.
abstract: 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). We investigated the principal characteristics of this assay by gel filtration of lipoproteins and their particle size distribution. We developed a simple assay and evaluated its performance with the Hitachi-7170 analyzer.
  
  
  RESULTS
  Polyoxyethylene-polyoxybutylene block copolymer (POE-POB) exhibited favorable selectivity toward VLDLR and IDL fractions. POE-POB removed apolipoprotein (apo) E and apo C-III from IDL particles in the presence of cholesterol esterase (CHER), and the particle size distribution of IDLs became smaller after the reaction. These results revealed that IDL particles are specifically modified in the presence of CHER and POE-POB, making their component cholesterol available for enzymatic assay. Addition of phospholipase D improved the reactivity toward chylomicron remnants (CMRs). We found a high correlation [y = 1.018x- 0.01 mmol/L, r = 0.962 (n = 160)] between the proposed assay and the immunoseparation assay in serum from healthy individuals.
  
  
  CONCLUSIONS
  The homogeneous assay described in this report can measure TRL remnant cholesterol, including CMRs, VLDLRs, and IDLs, with high sensitivity and specificity.
authors: Scientific and Technical Affairs Department, Kyowa Medex Co., Ltd., Tokyo, Japan.
authors: Kazuhito
authors: K
authors: Miyauchi
authors: Norihiko
authors: N
authors: Kayahara
authors: Masato
authors: M
authors: Ishigami
authors: Hideyuki
authors: H
authors: Kuwata
authors: Hideharu
authors: H
authors: Mori
authors: Hiroyuki
authors: H
authors: Sugiuchi
authors: Tetsumi
authors: T
authors: Irie
authors: Akira
authors: A
authors: Tanaka
authors: Shizuya
authors: S
authors: Yamashita
authors: Taku
authors: T
authors: Yamamura
mesh_terms: D001322:Autoanalysis; D002784:Cholesterol / Q000097:blood*; D015243:Cholesterol, VLDL / Q000097:blood*; D002850:Chromatography, Gel; D053298:Chylomicron Remnants / Q000097:blood*; D004852:Epoxy Compounds; D006801:Humans; D006952:Hyperlipoproteinemia Type III / Q000378:metabolism; D007202:Indicators and Reagents; D008074:Lipoproteins / Q000097:blood*; D053419:Lipoproteins, IDL / Q000097:blood*; D010739:Phospholipase D; D011092:Polyethylene Glycols; D013501:Surface-Active Agents; D014280:Triglycerides / Q000097:blood*; D014461:Ultracentrifugation
chemical_list: D015243:Cholesterol, VLDL; D053298:Chylomicron Remnants; D004852:Epoxy Compounds; D007202:Indicators and Reagents; D008074:Lipoproteins; D053419:Lipoproteins, IDL; D013501:Surface-Active Agents; D014280:Triglycerides; C112017:remnant-like particle cholesterol; C087757:poly(ethylene oxide)-poly(butylene oxide) copolymer; D011092:Polyethylene Glycols; D002784:Cholesterol; D010739:Phospholipase D