Isoelectric focusing of creatine kinase MM isoforms and its application for diagnosis of acute myocardial infarction

Noninvasive assessment of reperfusion and reocclusion after thrombolysis in acute myocardial infarction

The clinical significance of ST-segment changes and of the time course of appearance in serum of different cardiac proteins has been reviewed for the diagnosis of coronary reperfusion and reocclusion after thrombolysis. In particular, the value of serial 12-lead electrocardiographic (ECG) studies, of Holter monitoring, and of continuous multilead computer-assisted ECG monitoring is compared. Regarding the serum proteins, the clinical significance of reperfusion indices described so far for serum creatine kinase (CK), its isoenzyme serum creatinine kinase MB, the CK isoforms, and myoglobin is reviewed. Emphasis is placed on (1) the calculation method used for deriving the reperfusion indices; (2) the sensitivity and the specificity of the reperfusion indices; (3) the minimum turn-around time needed to produce the reperfusion indices (depending on the practicability of the analytical and calculation methods and their applicability in an emergency laboratory); (4) the ability of the indices to produce reliable estimates of reperfusion efficacy of the thrombolytic agents under study; and (5) the ability of the marker proteins to detect reinfarction as well as the suitability of the markers to detect real-time necrosis.

Creatine kinase MB isoforms for early diagnosis and monitoring of acute myocardial infarction

MB isoforms of creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2, CK) in 848 sera obtained from 80 patients with acute myocardial infarction (AMI) were studied by agarose gel isoelectric focusing. In 173 sera (20%) from 25 patients (31%), a new isoform designated as MB3 (pI 5.4) was detected at the cathodal side of MB2 (pI 5.2) in addition to the previously known MB2 and MB1 (pI 5.1). The new isoform MB3 was found in the extract of the cardiac muscle. MB3 was dominant in the sera at an earlier stage and a shorter period of time after AMI: 1-14 h (range), 1-29.5 h and 4-154 h for MB3, MB2 and MB1 dominant, respectively. MB3 was therefore found to be an earlier and a shorter phase indicator for AMI than MB2 or MB1. However, MB2 greater than 1 was the most prevalent pattern at the time of admission to the hospital. In AMI, specificity was 96.2%, 92.4% and 90.6%, and sensitivity was 20.4%, 88.9% and 97.6%, for MB3, MB2 and MB1 isoforms, respectively. CK-MB isoform patterns were biased to MB1 dominant in the deceased group, and to MB2 dominant in the surviving group. Therefore determination of CK-MB isoforms is also useful in the course of observation of AMI. The fourth isoform, MB0 (pI 5.0), was detected at the anodal side of MB1. MB0 was a minor band of the CK-MB isoform which appeared when serum CK-MB activity increased.

Identification by isoelectric focusing of creatine kinase-MM isoforms in the plasma and striated muscle of pigs

Total creatine kinase (CK) and CK-MM isoforms were determined in plasma and longissimus dorsi muscle extracts from normal pigs. Based on their total CK activity, the pigs were divided into two groups. Pigs of group 1 (n = 16) had a mean plasma total CK of 298 +/- 16 U/L and the distribution of the CK-MM isoforms was 65.7 +/- 2.5% CK-MM3, 18.9 +/- 1.6% CK-MM2 and 15.3 +/- 1.5% CK-MM. In group 2 (n = 18; 826 +/- 75 U/L total CK) four isoforms were observed: 3.1 +/- 0.9% CK-MM, 67.9 +/- 3.0% CK-MM3, 21.5 +/- 2.3% CK-MM2 and 7.5 +/- 1.3% CK-MM. The differences between the two groups of pigs were significant (p less than 0.001) for CK-MM1 and the presence of CK-MM. Four CK-MM isoforms were also detected in longissimus dorsi muscle homogenates: 45.6 +/- 8.1% CK-MM, 32.6 +/- 11.7% CK-MM3, 16.6 +/- 2.3% CK-MM2 and 5.1 +/- 2.8% CK-MM1. The release of CK-MM isoforms from muscle into plasma seems to be unrelated to the concentration of these isoforms in striated muscle.

Rapid diagnosis of myocardial infarction and reperfusion by assay of plasma isoforms of creatine kinase isoenzymes

Early, reliable detection of acute myocardial infarction and of coronary artery recanalization, in patients receiving thrombolytic agents, is essential to guide the course of therapy. Because the MM and MB isoenzymes of creatine kinase (CK) released from myocardium, undergo time-dependent removal of carboxyl terminal lysine residues from each monomer during exposure to circulating carboxypeptidase N, plasma profiles of the resulting isoforms are altered promptly and markedly after the release of new tissue isoenzymes. This paper reviews the results of experimental and preliminary clinical studies, showing the potential for rapid diagnosis of myocardial infarction and coronary artery recanalization by analysis of isoforms of CK isoenzymes in plasma.