改良缺血修饰白蛋白测定方法（白蛋白-钴结合试验）的建立

目的建立改良的缺血修饰白蛋白（IMA）测定方法[白蛋白-钴结合（ACB）试验]。方法以1-亚硝基-2-萘酚（NN）代替二硫苏糖醇（DTT）作为显色剂,确定试验的基本条件（最佳波长、反应时间、试剂稳定性等）,并对该试验的精密度、敏感性、线性等进行评价。测定急性心肌梗死（AMI）和胸痛患者的IMA值并进行统计学分析。结果改良ACB试验最佳吸收波长为410 nm,反应体系0～25 min时吸光度值变化稳定,试剂在室温和4℃30 d内性能稳定,反应体系线性良好。批内变异系数（CV）为2.67%,批间CV为5.44%。应用显色剂NN对钴离子（Co2＋）的最低检出限为0.488 mg/L,应用DTT为7.812 mg/L。三酰甘油（TG）〈2.02 mmol/L、血红蛋白（Hb）〈6.9 g/L、总胆红素（TBil）〈66.0μmol/L时无干扰。AMI组为（1.195±0.320）吸光度单位（ABSU）,胸痛组为（0.855±0.068）ABSU,二者差异有统计学意义（P〈0.01）。结论以NN作为显色剂测定IMA的ACB试验灵敏、方便、简单,适合批量测定。     

应用全自动生化分析仪测定缺血修饰白蛋白

目的建立白蛋白钴结合(ACB)试验检测缺血修饰白蛋白(IMA)。方法应用日立7600型全自动生化分析仪,采用ACB法测定IMA,并测定血清中不同白蛋白浓度,以观察白蛋白对其影响。结果ACB方法批内变异系数(CV)为5.0%,批间CV为1.6%。不同浓度的人血清白蛋白ACB法测定结果是线性的,回归方程为Y=0.029 1.57X,r=0.995,P=0.000。黄疸对测定无明显影响;溶血(5 g/dL)和脂血(0.4%)对测定有干扰。健康人群参考范围为79.6 U/mL。结论IMA是评价心肌缺血的有效诊断工具,采用全自动生化分析仪建立测定IMA的方法方便、简单,可以大批量测定。     

应用全自动生化分析仪测定缺血修饰白蛋白

目的建立白蛋白钴结合（ACB）试验检测缺血修饰白蛋白（IMA）。方法应用日立7600型全自动生化分析仪,采用ACB法测定IMA,并测定血清中不同白蛋白浓度,以观察白蛋白对其影响。结果ACB方法批内变异系数（CV）为5.0%,批间CV为1.6%。不同浓度的人血清白蛋白ACB法测定结果是线性的,回归方程为Y=0.029＋1.57X,r=0.995,P=0.000。黄疸对测定无明显影响;溶血（5 g/dL）和脂血（0.4%）对测定有干扰。健康人群参考范围为79.6 U/mL。结论IMA是评价心肌缺血的有效诊断工具,采用全自动生化分析仪建立测定IMA的方法方便、简单,可以大批量测定。     

白蛋白钴结合试验测定缺血修饰白蛋白方法学评价

目的白蛋白钴结合（ACB）试验测定缺血修饰白蛋白（IMA）,并确定参考正常范围。方法应用日立7600—120E型全自动生化分析仪,采用ACB法测定IMA。结果ACB法批内变异系数（CV）为1．43％,批间CV为1．70％。不同浓度的IMA结果线性相关,回归方程为Y=-13．752X＋83．835,r=0．9586。脂血（TG≤20．5mmol／L）、黄疸（TBIL≤259．6）,对测定无影响,溶血对IMA测定影响较大。健康人群的参考范围为≥62．84U／ml,心肌缺血患者为54．49U／ml。结论IMA是诊断心肌缺血的有效工具,应用全自动生化分析仪检测IMA快速、准确、简便。     

缺血修饰白蛋白和D-二聚体及肌钙蛋白Ⅰ在急性冠状动脉综合征早期诊断中的应用

目的 探讨缺血修饰白蛋白(IMA)、D-二聚体及肌钙蛋白Ⅰ(cTn Ⅰ)对急性冠状动脉综合征( ACS)的早期诊断价值.方法 收集2009年12月至2010年3月河北医科大学第三医院急诊科胸痛患者113例,30名健康体检者为健康对照组.根据胸痛发作至采血时间窗分为3h以内组52例和3～6h组61例;根据临床最后确诊分为非缺血性胸痛组(NICP)31例和ACS组82例,其中ACS组又分为不稳定性心绞痛(UA)组51例,非ST段抬高心肌梗死(NSTEMI)组18例和ST段抬高心肌梗死(STEMI)组13例;用白蛋白-钴结合(ACB)方法测定血清IMA,用全自动血凝分析仪和免疫化学发光分析仪测定D-二聚体和cTn Ⅰ.采用方差分析和SNK检验分析比较各组患者IMA、D-二聚体、cTn Ⅰ水平变化,并采用x2检验分析评价其单独和联合应用对ACS早期诊断的敏感度、特异度和准确性.结果 ACS患者中的UA组、NSTEMI组、STEMI组血清IMA水平分别为(0.722±0.181)、(0.601±0.122)、(0.631±0.153)吸光度单位(ABSU)、血浆D-二聚体水平分别为(0.485±0.124)、(0.571±0.181)、(0.748±0.094) mg/L,血清cTn Ⅰ水平分别为(0.076±0.027)、(0.059±0.038)、(0.065±0.015) μg/L,均高于NICP组[血清IMA(0.338±0.065) ABSU、血浆D-二聚体(0.368±0.078) mg/L、血清cTnⅠ (0.022 ±0.007) μg/L]和健康对照组[血清IMA (0.292±0.058) ABSU、血浆D-二聚体(0.267±0.052) mg/L、血清cTnⅠ (0.029±0.016) μg/L],差异有统计学意义(F值分别为3.613、3.289和3.521,P均＜0.05).胸痛3h以内组和3～6h组ACS患者血清IMA水平分别为(0.665±0.104)、(0.520±0.073)ABSU,高于健康对照组的(0.292±0.058) ABSU,差异有统计学意义(F=3.58,P＜0.05).胸痛3～6h组ACS患者血浆D-二聚体及血清cTn Ⅰ水平分别为(0.634±0.213) mg/L和(0.079±0.032)μg/L,均高于健康对照组的(0.267±0.052) mg/L及(0.029±0.016)μg/L,差异有统计学意义(q值分别为4.24和3.46,p值均＜0.05).单独应用IMA诊断ACS的敏感度为85.36％、特异度为70.97％、准确性为81.42％,IMA、D-二聚体及cTn Ⅰ联合应用诊断ACS的敏感度为97.56％,特异度为58.06％、准确性为86.73％.结论 血清IMA是ACS发病早期心肌缺血的敏感指标,优于cTn Ⅰ和血浆D-二聚体对ACS发病早期的心肌缺血诊断作用.联合检测IMA、D-二聚体及cTn Ⅰ可以提高诊断的敏感度和特异度,对指导临床早期诊断ACS有一定价值.     

缺血修饰白蛋白在老年急性心肌缺血诊断中的应用价值

目的探讨血清缺血修饰白蛋白（I MA）水平检测在老年心肌缺血诊断及鉴别诊断中的应用价值。方法采用白蛋白钴结合试验（ACB试验）间接测定50例急性冠状动脉综合征（ACS）、100例非缺血性心脏病（对照组）患者的血清I MA水平,比较ACS患者胸痛发作后3小时内血清ACB值与对照组患者血清ACB值的差异;比较ACS患者中不稳定型心绞痛（UA）患者与急性心肌梗死（AMI）患者ACB值差异;获得识别急性心肌缺血的最佳ACB值截断值。结果 ACS患者胸痛发作后3小时内血清ACB值为（79.62±9.20）kU/L,明显低于对照组（93.77±8.53）kU/L（P〈0.01）;UA患者胸痛发作后3小时内ACB值为（80.96±8.63）kU/L,与AMI患者的（79.48±11.06）kU/L比较差异无统计学意义（P〉0.05）。应用受试者工作特征（ROC）曲线分析得出早期识别急性心肌缺血的ACB值截断值为85kU/L,以此值诊断急性心肌缺血的敏感度为88%,特异度为82%。结论 I MA是老年急性心肌缺血早期诊断的敏感生物标记物,但不是鉴别急性心肌缺血与AMI的生物学指标。应用ACB值最佳截断值诊断急性心肌缺血,有较高的敏感度和特异度。     

妊娠相关血浆蛋白-A、缺血修饰白蛋白在急性冠脉综合征早期诊断中的价值

[目的]探讨妊娠相关血浆蛋白-A(PAPP-A)及缺血修饰白蛋白(IMA)在急性冠脉综合征(ACS)早期诊断中的意义.[方法]87例疑似ACS患者在胸痛发作3h内采取静脉血测定PAPP-A、IMA及相关指标并进行分析.经冠状动脉造影证实冠脉正常者作为对照组27例,稳定性心绞痛(SAP)组20倒,ACS组40例,包括不稳定性心绞痛(UAP)23例、急性心肌梗死(AMI)17例.[结果]①ACS组中PAPP-A及IMA含量(16.19±2.13 mIU/L,0.608±0.097ABSU)明显高于SAP组(4.720±1.960 mIU/L,0.436±0.022 ABSU)及对照组(4.390±1.150 mIU/L,0.246±0.135 ABSU)(P<0.001),IMA与PAPP-A呈显著正相关(r=0.80,P<0.01).②PAPP-A及IMA对检测ACS早期的灵敏度分别为85%及80%,两者联合灵敏度达95%.[结论]PAPP-A及IMA在外周血中明显升高,可能是ACS早期的预测因子,两者联合检测可提高对ACS早期诊断能力.     

北京地区汉族人群缺血修饰白蛋白参考范围的建立

目的：应用全自动生化分析仪建立缺血修饰白蛋白（IMA）的生物学参考范围。方法：在Hitachi7170A全自动生化分析仪上设计合理参数,采用白蛋白钴结合（ACB）试验测定IMA,测定561例健康人群血清IMA含量,建立健康人群IMA参考范围。结果：健康人群中小于30岁人群的5%参考下限为67 U/ml,〉30岁人群的5%参考下限为64 U/ml。结论：用全自动生化分析仪建立ACB方法测定的IMA参考范围,有助于临床对心肌缺血的诊断。     

缺血修饰白蛋白在急性冠脉综合征早期诊断中的价值

目的探讨缺血修饰白蛋白(IMA)对急性冠脉综合征(ACS)的早期诊断价值以及ACS患者血清IMA水平与冠状动脉病变程度的关系。方法在HITACHI公司7170全自动生化分析仪上,用间接白蛋白钴结合试验(ACB法)测定40例急性冠脉综合症患者(包括23例不稳定心绞痛患者和17例急性心肌梗死患者)、18例因胸痛入院的非ACS患者和102例健康门诊体检人员血清IMA含量。将IMA测定结果绘制ROC曲线并通过分析制定区分ACS与对照(非ACS胸痛患者和健康体检者)的最适cutoff值。将冠状动脉病变程度用Gensini积分表示,分析IMA值与冠脉病变严重程度的相关性。结果不稳定心绞痛组和急性心肌梗死组间IMA无差异无统计学意义,ROC曲线下面积为0.789,在cutoff值ABUS/ml=85.34时敏感性和特异性分别为79.2%和70.9%。IMA水平与反应冠脉病变严重程度的Gensini积分的相关系数为0.15。结论 IMA是心肌缺血的敏感指标,区分可逆性缺血与梗死的能力较差,不能反映冠状动脉病变程度。     

缺血修饰清蛋白在急性心肌缺血早期诊断中的临床价值

目的 探讨血清缺血修饰清蛋白(IMA)测定在急性心肌缺血早期的临床价值.方法 采用间接清蛋白-钴结合实验(ACB)测定80例确诊为急性冠状动脉综合征(ACS)的患者及60例因胸痛入院但最后确诊为非缺血性心脏病患者,胸痛发作3 h内的血清IMA水平和临床常用的心肌损伤标志物心肌肌钙蛋白T(cTnT)、肌酸激酶同工酶(CK-MB).通过绘制ACB在该人群中用于诊断ACS的受试者工作特征(ROC)曲线判定最佳临界值,确定IMA诊断ACS的敏感性、特异性、阳性预测值和阴性预测值.结果 与对照组比较,ACS组ACB明显降低,为(49.75±10.25)U/mL,经t检验,差异有统计学意义(P<0.01),而ACS组中,急性心肌梗死(AMI)组与不稳定型心绞痛(UA)组间ACB比较差异无统计学意义(P>0.05);cTnT、CK-MB水平分别为(1.24±0.67)ng/mL、(35.14±9.37)U/L,经t检验,差异无统计学意义(P>0.05).根据ROC曲线,当cut-off值为63.6 U/mL时,IMA检测的敏感性、特异性、阳性预测值和阴性预测值较高,分别为81.27%、86.58%、84.19%和82.57%.结论 缺血修饰清蛋白是早期诊断心肌缺血的敏感标志物,对于急性冠状动脉综合征的早期诊断和治疗具有重要的临床意义.     

Effect of albumin concentration and serum matrix on ischemia-modified albumin

Objectives:There is concern that ischemia-modified albumin (IMA) levels measured by albumin cobalt binding (ACB) assay reflect mainly albumin concentrations rather than myocardial ischemia.Design and methods:Serum matrix and proteins were separated from a serum pool by a membrane filter. Two series of pools with albumin concentrations of 10, 20, 30, 40, 50, and 60 g/L were prepared either with human albumin or serum protein fraction. IMA values of these pools were measured in quintiplicate.Results:There was a strong negative correlation between IMA and albumin levels in both pools. IMA change corresponding to each 10 g/L difference in albumin concentration was 37% and 48% in these pools.Conclusions:ACB assay reflects albumin concentrations rather than IMA. Primary predictor of IMA in serum matrix is albumin concentration.     

Analytical performance of the Albumin Cobalt Binding (ACB) test on the Cobas MIRA Plus analyzer.

Recently a new biological marker, Ischemia Modified Albumin (IMA), measured by the Albumin Cobalt Binding (ACB) test, was introduced for detection of myocardial ischemia. During ischemia, the metal binding capacity of albumin for certain transition metals like cobalt is reduced. The precise mechanism of action for producing IMA is not known but appears to be related to the production of reactive oxygen species that modify the metal binding sites. The ACB test is a quantitative assay that detects IMA by measuring the cobalt binding capacity of albumin in human serum. We evaluated the analytical characteristics of the ACB test, and reagent and specimen stability, using the Cobas MIRA Plus instrument. Coefficients of variation for within-run and between-run assays were <4%. No significant interference was observed for concentrations of triglycerides and hemoglobin up to 7 mmol/l and 3.8 g/l, respectively. No interference was apparent with bilirubin. Measures from paired samples of heparinized plasma and serum were not equivalent. The assay is validated for commercial use with serum, therefore our study reported results for serum specimens only. All assays were completed within 5 hours after blood withdrawal. The one-sided upper 95th percentile, calculated for the ACB test in 150 healthy subjects, was 87.00 U/ml. There was no observed difference between men and women or with age. We conclude that the ACB test adapted on the Cobas MIRA Plus analyzer is satisfactory, but strict attention to sample handling procedures is necessary to maintain stability of the analyte.     

High-workload endurance training may increase serum ischemia-modified albumin concentrations.

The measurement of cardiac troponins has emerged as the biochemical "gold standard" for the diagnosis and management of patients with acute chest pain. However, earlier markers should support investigation strategies, as several patients with acute coronary syndrome might present with non-diagnostic concentrations. Ischemia-modified albumin (IMA), measured by the albumin cobalt binding (ACB) assay, was recently proposed for early detection of myocardial ischemia. To establish the potential influence of endurance training on the diagnostic approach to patients with suspected myocardial injury, cardiac troponin T (cTnT), creatine kinase isoenzyme MB (CK-MB), myoglobin and IMA were evaluated in healthy individuals subjected to different aerobic workloads. The concentrations of both IMA and CK-MB were significantly increased in athletes subjected to high-workload endurance training, whereas the concentration of cTnT and myoglobin was not influenced by physical exercise in the medium term. Taken together, our results demonstrate that demanding aerobic physical activity might influence the generation of IMA, which might be increased in the medium term following high-workload endurance training, while the concentration of other conventional markers of myocardial injury remains non-diagnostic.     

缺血修饰清蛋白全自动分析法的建立及初步性能评价

目的建立缺血修饰清蛋白(IMA)全自动生化分析仪检测方法 ,并对该方法进行初步性能评价。方法采用清蛋白钴结合试验(ACB)测定IMA,利用在分光光度法检测中寻找的高、低浓度样本,在HITACHI-7170A全自动生化分析仪上设计合理参数,建立ACB的校准曲线,并对所建立的方法进行性能分析评价。结果建立的7170A全自动生化分析法测定IMA其健康体检组混合血清和急性冠状动脉综合征(ACS)组混合血清的批内和批间变异系数分别为0.97%和1.46%,1.01%和1.73%,实验的重复性较好。把高、低值按一定比例混合后进行线性回归分析显示,线性回归方程式为:Y=0.1794X+0.029,相关系数(r)=0.9959,线性良好。检测健康对照组和ACS组IMA浓度,检测结果显示,ACS组IMA明显高于健康对照组。结论在HITACHI-7170A全自动生化分析仪成功建立ACB测定IMA的方法 ,本法具有准确性高、重复性好、反应稳定及操作简单等优点,可作为辅助ACS诊断的早期心肌缺血标志物。     

Assay of ischemia-modified albumin and C-reactive protein for early diagnosis of acute coronary syndromes

Diagnosis of cardiac ischemia in patients coming to emergency departments (ED) with symptoms of acute chest pain is often difficult. Many markers are sensitive and specific for the detection of myocardial necrosis but may not rise during reversible myocardial ischemia. Ischemia-modified albumin (IMA) has recently been shown to be a sensitive and early biochemical marker of ischemia. The variation laws were observed by measuring IMA and C-reactive protein (CRP) of 113 patients in ED within 12 hr after onset of chest pain. In the observation, blood was taken for IMA and CRP. Patients underwent standardized triage, diagnostic procedures, and treatment. Results of IMA and CRP were correlated with final diagnoses of nonischemic chest pain (NICP) and acute coronary syndrome (ACS). There were obvious distinction of IMA and CRP levels between the NICP and ACS groups. Receiver operator characteristic (ROC) curve analysis was used to determine the optimal cutoff of this assay for identifying individuals with ACS patients from NICP. The area under the curves of IMA is 0.948. The sensitivity and specificity of albumin cobalt binding (ACB) at a cutoff value of 70.0 units/mL were 94.4% and 82.6%, respectively. The area under the curves of CRP is 0.746. Sensitivity and specificity of CRP at a cutoff value of 3.16 mg/L were 70.0% and 73.9%, respectively. Negative predictive value (NPV) of IMA and CRP for ischemia origin was 79.2% and 38.6%, respectively. IMA may make an early diagnosis of acute coronary ischemia, and will improve the early diagnostic sensitivity and specificity of ACS.