| PART? Performance Characteristics and the Stability in Storage of the Lipoprotein-associated Phospholipase A2 by Enzyme Kinetic Method Objective To analyze the performance characteristics of Lp-PLA2 by enzyme kinetic method;to evaluate the effect of specimen types to Lp-PLA2 activity;to assess the stability of Lp-PLA2 activity in different storage conditions.Methods The performance characteristics of Lp-PLA2 activity including imprecision,accuracy and reference interval were evaluated by enzyme kinetic method;residual serum and plasma were collected for comparing the difference of Lp-PLA2 activity in specimen of different types;for analyzing the change of Lp-PLA2 activity in different storage conditions,residual serum and plasma were stored in different temperatures(ambient temperature,4?,-20? and-80 ?)and different times(one day,three days,seven days,two weeks,one month,two months)respectively.Results The repeatability and reproducibility CVs of Lp-PLA2 activity were 1.43%-1.77%,1-81%-2.63%,respectively,the average bias was 0.33%,the reference interval of serum Lp-PLA2 activity was 415±113 U/L,and there was a statistically significant sex difference in serum LpPLA2 activity(males 479±114 U/L,females 423±106 U/L,p < 0.05).Serum Lp-PLA2 activity was slightly higher than plasma Lp-PLA2 activity(about 6%),but there was no statistically significant difference(p > 0.05).In 4? and-20? storage conditions,the change of Lp-PLA2 activity in serum and plasma was slightly within two months;and the change was minimal in-80?(the change of Lp-PLA2 activity was < 2%),-80? was a temperature suitable for the long-term storage of specimens.Conclusion The imprecision and accuracy of Lp-PLA2 activity by enzyme kinetic method is well;and the stability of Lp-PLA2 activity in storage is well;both serum and plasma are suitable for the detection of Lp-PLA2 activity;the analytical performance of Lp-PLA2 activity could meet the clinical application.PART ? The Clinical Value of the Lipoprotein-associated Phospholipase A2 by Enzyme Kinetic MethodObjective To assess the clinical value of Lp-PLA2 activity,to analyze the correlations of Lp-PLA2 with traditional cardiovascular risk factors.Methods Residual serum specimens were collected randomly from CHD patients,hypercholesterolemia patients and healthy persons of the Health Examination Center,and the specimens were divided into CHD group,high TC group and the control group.CHD group and high TC group were compared with the control group in Lp-PLA2 activity,respectively.And the CHD group was divided into different subgroups by different lipid index level.It included high TC subgroup,low TC subgroup;high TG subgroup,low TG subgroup;high LDL subgroup,low LDL subgroup.And Lp-PLA2 activity of all subgroups was compared with the control group,respectively.In CHD group,the correlation of Lp-PLA2 and TC?TG?LDL?Apo B and hs-CRP was analyzed.The ROC curve was used for analyzing the value of combination of all indicators in CHD.Results Lp-PLA2 activity of CHD group and high TC group was higher obviously than the control group,and there was statistically significant difference(both of p value < 0.05).And Lp-PLA2 activity of the subgroups of CHD group was higher than the control group.The correlation between Lp-PLA2 and traditional cardiovascular risk factors showed poor correlation between Lp-PLA2 and hs-CRP(R2 = 1E-06,p > 0.05),certain correlation with TG(R2 = 0.0408,p < 0.001),higher correlation with TC and LDL(R2 = 0.3544,p < 0.001;R2 = 0.4157,p < 0.001,respectively),and the highest correlation with Apo B(R2 = 0.4545,p < 0.001).The AUC of ROC for the combination of all indicators was 0.873(0.810-0.936).Conclusion Lp-PLA2 has important clinical value in CHD,the combination of Lp-PLA2 and traditional cardiovascular risk factors is more helpful for the diagnosis and risk forecast of CHD. |
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