Recent approaches to the standardization of cardiac markers

The development of commercial assays for the determination of cardiac proteins has been one of the most important innovations in the field of cardiovascular diagnostics in the last decade. Some assays are, however, inadequately appraised prior to their introduction to clinical use. This paper focuses on some important preanalytical, analytical and interpretative problems, and summarizes the status of the ongoing local and international standardization efforts. The most urgent issue at the moment is the development of international reference materials, which can be used for the calibration of different assays, thus decreasing between-assay biases. In order to achieve comparability of test results, another important item is the standardization of the epitopes of the antibodies used for the assay development. Efforts to improve the precision of cardiac marker assays are also warranted. Finally, the effect of storage time and temperature on apparent marker concentration and the possible influence of different anticoagulants on measured marker values should clearly be evaluated.     

血清肌红蛋白、尿酸、脑钠肽与慢性心力衰竭的相关性研究

目的：探讨血清肌红蛋白、尿酸、脑钠肽与慢性心力衰竭的相关性。方法：选取2005年1月～2010年8月于本院进行治疗的128例慢性心力衰竭患者为观察组，同时选取同期的128名健康体检人员为对照组，后将两组人员的血清肌红蛋白、尿酸、脑钠肽水平进行检测及比较。结果：经过研究比较发现，观察组的血清肌红蛋白、尿酸、脑钠肽水平均显著高于对照组，且患者随NYHA分级增高，心功能越来越差，这些血清因子水平也越来越高，差异有统计学意义或高度统计学意义（P〈0．05或P〈0．01）。结论：血清肌红蛋白、尿酸、脑钠肽与慢性心力衰竭有极大的相关性．值得临床进一步研究及探讨。     

Serum Myoglobin,Creatine Kinase and Creatine Kinase–MB as Mutually Supportive Indices of Myocardial Infarction and Infarct Size*

Abstract: Serum myoglobin, creatine kinase and creatine kinase–MB as mutually supportive indices of myocardial infarction and infarct size *. R. N. Johnson, W. F. Lubbe, C. J. Mercer, N. L. Sammel and R. M. Norris, Aust. N.Z. J. Med., 1982, 12, pp. 160–165. A comparison was made between the appearance of serum myoglobin and creatine kinase in 22 patients with acute myocardial infarction who were admitted to a coronary–care unit within four hours of onset of chest pain. The MB isoenzyme of creatine kinase was measured in 12 patients. The more rapid appearance and disappearance of myoglobin relative to creatine kinase and creatine kinase–MB was confirmed, as was the correspondence between their respective peak values. A significant correlation was also obtained between the area under the myoglobin time–course and the respective peak levels. Whereas creatine kinase activity declined exponentially from a single peak, myoglobin appeared in multiple episodes inadequately represented by a single peak value and having no clear clinical correlation. The role of myoglobin as a diagnostic aid in myocardial infarction is probably limited to its ability to support creatine kinase and creatine kinase–MB as indices of infarct size.     

Influence of the physical and chemical properties of magnetic nanoparticles on their performance in a chemiluminescence immunoassay

Objectives

Magnetic nanoparticles (MNPs) are important carriers in immunoassays. In this study, we investigated the influence of the physical and chemical properties of MNPs on their performance in a detection process.

Design and methods

A comparative study of the properties of two MNPs with sizes of 200 nm and 1 μm (MNP-200 nm and MNP-1 μm, respectively) was conducted using the following four aspects: nonspecific adsorption to proteins (IgG was used as a model protein), influence of magnetic nanoparticles on the chemiluminescence signal, response speed to an external magnetic field, and intensity of the detection signal.

Results

MNP-1 μm exhibited lower nonspecific adsorption to IgG in serum, a weaker interference with the chemiluminescence signal, and a higher response speed to the external magnetic field than the same amount of MNP-200 nm. An automated chemiluminescence immunoassay system based on MNP-1 μm was also established.

Conclusions

MNP-1 μm acts as an excellent carrier in an automated chemiluminescence immunoassay system for the analysis of serum samples from clinical patients.     

Myoglobin expression in renal cell carcinoma is regulated by hypoxia

Myoglobin is a member of the hemoprotein superfamily, which additionally includes hemoglobin, neuroglobin and cytoglobin. Cytoplasmic localized myoglobin functions as a radical scavenger and prevents hypoxia. Besides muscle tissue MB expression could also be observed in other tissues as well as in different types of cancer.     

恙虫病患者血清肌钙蛋白Ⅰ、肌红蛋白的测定

目的 探讨恙虫病患者测定血清肌钙蛋白、肌红蛋白的临床意义.方法 选取恙虫病患者342例,行心肌酶学、心电图检查、肌钙蛋白Ⅰ、肌红蛋白检测,部分患者进一步行超声心动图检查,并定期复查.同期我院查体人员60例作对照.结果 342例患者多项心肌酶学异常,肌红蛋白异常者多,与对照组相比有显著性差异.肌钙蛋白无明显改变.结论 恙虫病患者心肌损伤不明显,而骨骼肌损伤明显.不宜以血清酶学异常、心电图异常作为恙虫病心肌损害的诊断依据.     

急性冠脉综合征患者血浆D-二聚体和心肌标志物测定结果与分析

目的：探讨急性冠脉综合征（ACS）患者血浆D-二聚体和心肌标志物的水平及临床应用价值。方法：对200例ACS患者,其中不稳定型心绞痛（UAP）85例、非ST段抬高型心肌梗死（NSTEMI）59例、ST段抬高型心肌梗死（STEMI）56例的血浆D-二聚体和几种心肌标志物进行检测,并与同时选取的50例正常对照者进行比较。其中D-二聚体由法国Stago-STA-R全自动血凝仪完成;以双向测流免疫法检测患者心肌肌钙蛋白I（cTnI）、肌红蛋白（Myoglobin）、肌酸激酶同工酶（CK-MB）。结果：UAP组的D-二聚体水平为（11.6±7.3）mg/L、cTnI（0.24±0.15）ng/mL、CK-MB（16.3±7.3）ng/mL、Myoglobin（160.6±42.1）ng/mL;NSTEMI组分别为（13.9±6.7）mg/L、（0.38±0.35）ng/mL、（21.3±16.9）ng/mL、（183.4±48.9）ng/mL;STEMI组分别为（19.2±6.9）mg/L、（5.30±3.61）ng/mL、（50.3±18.6）ng/mL、（238.3±58.6）ng/mL。三组的血浆D-二聚体和几种心肌标志物的水平与正常对照组比较差异均有统计学意义（P〈0.01）;STEMI组各指标水平与UAP组、NSTEMI组比较差异均有统计学意义（P〈0.05）。结论：患者血浆D-二聚体和几种心肌标志物在辅助诊断UAP、NSTEMI、STEMI时具有重要的参考价值。     

高敏肌钙蛋白T检测在心肌梗死中应用价值的研究

目的:观察高敏肌钙蛋白T(hs-cTnT)、肌酸激酶同工酶质量(CK-MBmass)、肌红蛋白(Myo)和肌钙蛋白T(cTnT)在疾病发生及发展过程中的变化特征,研究高敏肌钙蛋白T检测在诊断急性心肌梗死方面的应用价值。方法:选取100例急性心肌梗死患者,分别在0 h、4 h、12 h抽取静脉血,正常对照组为68例空腹抽取静脉血,分别测定4项指标的含量,比较它们在不同时间内对AMI的诊断特性。结果:AMI患者发病入院后,hs-TnT的敏感性为91%,特异性为83%,阳性预测值为89%,阴性预测值为86%。结论:高敏心肌肌钙蛋白具有最好的灵敏度和较好的组织特异性,适合作为AMI早期检测指标。     

In situ hybridization of myoglobin mRNA: results on the skeletal muscles of normal subjects and patients with neuromuscular diseases

The intracellular localization of myoglobin(Mb) mRNA in the skeletal muscles of normal subjects and patients with Duchenne muscular dystrophy(DMD) or amyotrophic lateral sclerosis(ALS) was examined by in situ hybridization using a biotin-labeled cDNA probe. In cross sections of normal muscles, Mb mRNA signals were demonstrated to be diffusely distributed as granular reaction products throughout the sarcoplasm, and in longitudinal sections the products were observed preferentially on the A-band. In DMD or ALS muscles, the distribution of granular mRNA signals showed some similarities with that in normal muscles, although degenerated fibers revealed a heterogenous distribution of the signals. In DMD muscles, the optical density(OD) of stained signal was higher in non-atrophic fibers and lower in atrophic fibers than in normal muscles. In ALS muscles, the OD was lower than in normal muscles. These results suggest that Mb mRNA is distributed preferentially on the A-band of the muscle fibers, and that in diseased muscle fibers Mb synthesis is affected by pathological changes.Supported in part by a Research Grant(2A-2) for Studies on Nervous and Mental Disorders from the Ministry of Health and Welfare of Japan     

Myoglobin is a sensitive marker of increased muscle membrane vulnerability

Summary Changes in muscle proteins in serum after exercise were studied to evaluate the use of such proteins as indicators of increased muscle membrane vulnerability. Seventy-one women were asked to perform bicycle exercise for 45 min at a moderate load; four proteins (creatine kinase — CK, myoglobin — Mb, aldolase — Ald and pyruvate kinase — PK) were measured in serum up to 24 h after exercise. Twenty-one women were carriers of Duchenne's muscular dystrophy (DMD); these are known to show an elevated serum CK activity at rest, as well as an increased CK response after exercise. Fifty women without a family history of neuromuscular disease were tested to obtain normal values: they showed a small peak (18%) of CK activity 8h after exercise, and an even smaller peak of Mb (9%) 1h after exercise. The mean post-exercise increase for both CK and Mb in the 21 DMD carriers was significantly higher than in controls; the maximum of Mb, on average 70% of baseline levels, was reached 1h after exercise and was higher than that for CK (48%), which was reached 8 h after exercise. It is concluded that myoglobin levels after exercise are a good index of increased vulnerability of the muscle membrane.