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sLDL-EX "Seiken" (sLDL) assay

Product Method Size Catalog Price Quantity
sLDL-EX "Seiken" (sLDL) assay Clearance R1 1 x 19.8ml, R2 1 x 8.6ml 562616 $1607.78
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  • Format
    Liquid ready-to-use
  • Assay Range
    4 - 100mg/dl
  • Working Stability 2-8 °C
    30 days
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Intended Use

The s LDL-EX “SEIKEN” kit is for the quantitative determination of small, dense (sd) LDL cholesterol (-C) in human serum or plasma. The device is intended to be used in clinical laboratories on routine clinical chemistry analyzers capable of accommodating two reagent assays. The measurement of sd LDL-C, when used in conjunction with other biochemical markers and coronary risk factors, is useful in the prediction of coronary artery disease/coronary heart disease (CAD/CHD) risk and the assessment of CAD/CHD severity in individuals with intermediate CAD/CHD risk.

Clinical Significance

LDL-C is considered a critical risk factor for developing CHD and cardiovascular disease (CVD). The qualitative features of the LDL particles also play an important role in the development of CHD, particularly in view of the predominance of sd LDL particles. sd LDL particles have been suggested to be highly atherogenic due to their higher penetration into the arterial wall, their lower binding affinity for the LDL receptor, their prolonged plasma half-life and their lower resistance to oxidative stress compared to that of large buoyant LDL(L LDL).

A recent report has confirmed that a predominance of sd LDL-C is a strong and independent predictor of CAD/CHD (5). Another study demonstrated that the LDL size is markedly smaller, and that small, dense LDL-cholesterol levels are significantly higher, in CAD/CHD patients than in controls; there also is a clear relationship between sd LDL levels and the severity of CAD/CHD.

To date, ultracentrifugation and electrophoresis-based methods are used for the measurement of sd LDL-C but these methods are both laborious and time-consuming. The s LDL-EX “SEIKEN” test is a direct method for the quantitative determination of sd LDL-C, using automated chemistry analyzers capable of accommodating two-reagent assays. The test is completed within 10 minutes.


The assay consists of two steps and is based on the technique to use well-characterized surfactants and enzymes that selectively react with certain groups of lipoproteins. In the first step, non-sd LDL lipoproteins, that is, chylomicrons, VLDL, IDL, L LDL and HDL are decomposed by a surfactant and sphingomyelinase (SPC) in Reagent-1 that is reactive to those non-sd LDL lipoproteins. The cholesterol released from such non-sd LDL lipoproteins is then degraded to water and oxygen by the action of enzymes. Cholesterol ester is hydrolyzed by the cholesterol esterase (CHE) and then oxidized by the cholesterol oxidase (CO). Produced hydrogen peroxides are finally decomposed to water and oxygen by the catalase.

In the second step, another surfactant in Reagent-2 releases cholesterol only from sd LDL particles and cholesterol released from sd LDL is then subject to the enzymatic reactions. As catalase in the reaction mixture is inhibited by sodium azide in Reagent-2, hydrogen peroxides, produced from the reaction with the cholesterol esterase and cholesterol oxidase, then develop a purple-red color with the coupler in the presence of peroxidase (POD).