| Morbidity and mortality rates among patients with coronary heart disease (CHD), remain high in our country. Acute coronary syndrome (ACS) is the most common prevalence, with which patients often complained chest pain. But this symptom is most commonly caused by relatively low-risk disorders, such as gastroesophageal, musculoskeletal, or anxiety syndromes. It is difficult to determine which patients will progress satisfactorily and which patients will have poor outcomes. Researches had indicated that the inflammatory process related to oxidized low-density lipoprotein (OX-LDL), plays a key role in the aetiology and pathogenesis of atherosclerosis and plaque formation. OX-LDL also induces formation of specific antibodies (OX-LDLAb), which have been demonstrated in the sera of human and animal models. Thus, there are great interests within the research community in determining whether the levels of serum OX-LDL and OX-LDLAbs, and which type of OX-LDLAbs, could be used to identify CHD from these patients with chest pain, and evaluate the severity of the disease process, and therefore serve as a prognostic tool for clinicians. This dissertation constituted of the following four parts, aims to explore the clinical significances of OX-LDL and its antibodies in patients with acute chest pain.Part oneNative LDL(n-LDL) has been obtained after serum ultracentrifugation, and then been oxidized with CuSO4 for 8h(Cu++-OX-LDL). Through conventional hybridoma techniques, which screened by Cu++-OX-LDL and n-LDL, five novel murine monoclonal antibodies only against OX-LDL have been harvested. Western blotting documented none of them reacted to n-LDL. Part twoBasing on two of five novel murine monoclonal antibodies, we have established a new method capable of measuring the very low concentrations of OX-LDL. When one monoclonal antibody was precoated onto microtiter wells prior to carrying out a sandwich ELISA using another one conjugated with horseradish peroxidase (HRP), it was possible to detect 6.25ng protein of Cu++-OX-LDL).The detection of OX-LDL was dependent on the presence of precoated monoclonal antibody. Under the same sandwich ELISA condition, n-LDL, high density lipoprotein (HDL) and very low density lipoprotein(VLDL) showed very low absorbance.The level of LDL oxidation of normal human subjects was found to be 36.6+9.33 units per microliter,where one unit was defined as the reactivity corresponding to 1 ug of copper-induced OX-LDL by this assay. Part threewe have optimized several enzyme immunoassays,which can measure autoantibodies to OX-LDL,malondialdehyde-induced LDL (MDA-LDL), oxidized phosphocholine-modified LDL(OXPC-LDL) and n-LDL.Optimizedprotocol was as follows: coating concentration 2ug/ml of antigen on microtiter wells, and 1% BSA as a blocking agent, sample dilution 1:101,conjugate dilution l:2000,and 1% BSA in sample and conjugate diluents.The positive samples from ACS were repeatedly measured within group for 10 times and between groups for 14 times, which showed coefficient of variance (CV) less than 10%. Part fourMETHODS AND RESULTS: In consecutive 309 patients undergoing quantitative coronary angiography for acute chest pain, we measured the levels of OX-LDL, cardiac troponin I(cTnI),and the levels of antibodies against OX-LDL, MDA-LDL, OXPC-LDL and n-LDL. With ANOVA analysis,We found significant differences of OX-LDL levels between acute myocardial infarction group and unstable angina group(109.55+28.09U/ml versus 98.12+28.16U/ml, P=0.042) , between groups of patients without and with ACS(67.5+26.2U/ml versus 102.4+28.6U/ml,p< 0.001), and between groups of patients without CAD and with CAD (64.75+25.73U/ml versus 94.5+30.6U/ml, P<0.001). No significant differences were indicated between groups of patients without CAD and stable angina pectoris (64.75+25.73U/ml versus 68.97+21.00U/ml,p > 0.05). We also investigated the associations of different expressions of various OX-LDL-related antibodies with CAD or ACS. When the results were expressed as the differences between OX-LDL antidodie...
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