MB Activity Research Articles

Total creatinine kinase and isoenzyme MB activity in serum and skeletal muscle of a patient with dermatomyositis.

Total creatine activity was greatly increased, and creatine kinase MB isoenzyme was measurable in the serum of a patient with dermatomyositis. In contrast, total CK activity in an extract of skeletal muscle from this patient was markedly decreased as compared with normal muscle extracts, but contained about the normal proportion of the MB isoenzymes, 1.5%. We believe skeletal muscle to be the source of the MB isoenzyme in the serum, because the patient's electrocardiographic pattern was normal and she had no signs or symptoms of myocardial infarction.

Etude de la myoglobinemie et de son evolution au cours de l'infarctus du myocarde

Thirty six patients suffering from myocardial infarction were investigated by assay of their serum myoglobin, total creatine kinase and creatine kinase isoenzyme MB activities. Determination of serum myoglobin presents, with regard to creatine kinase MB, two major advantages: a very early increase after the onset of the pain (about three hours later) and a very quick clearance, allowing the diagnosis of a second episode of necrosis after about one day.

Serum creatine kinase isoenzyme MB activity: Evaluation of a kit employing agarose-gel electrophoresis with overlay paper fluorescence scanning

A commercial kit for determining serum creatine kinase isoenzyme MB activity was evaluated. The kit employed agarose-gel electrophoresis followed by incubation of overlay paper on the agarose and then fluorescence scanning of the paper. Within-day coefficients of variation ranged from 24.9% for a specimen with no elevation of MB activity to 6.6% for a specimen with moderately elevated MB activity. The kit appeared to demonstrate MB in all sera and showed higher than expected values in recovery studies. The kit performed in a relatively linear fashion from 50 to 500 I.U./1 total creatine kinase activity. Hemolysis appeared to lower measured MB. For comparison with another method, specimens were also analyzed by microcolumn chromatography, which was found to incompletely separate isoenzymes. The kit produced lower values than microchromatography for specimens with low MB activities and higher values for specimens with elevated MB activities. Patients without corroborative evidence of myocardial injury showed a somewhat hyperbolic relationship between per cent MB and total creatine kinase activity, but MB activity was generally 4 I.U./1 or less. Although the kit had serious laboratory shortcomings, it may be as clinically useful as other methodologies.

Expression of creatine kinase isoenzymes in myogenic cell lines

Investigation of creatine kinase isoenzyme activity in several cloned myogenic cell lines showed differences in B-type subunit expression. In cultures of myoblasts isolated from rat skeletal muscle by selective cell plating and in the cell lines M58 and M41, the activity of the mononucleated cells was of the BB isoenzyme. After cell fusion, MM, MB, and BB isoenzymes were present; the main activity was of the MM isoenzyme. In the myogenic lines L8 and L84, in cultures of mononucleated cells, creatine kinase activity was absent or barely detectable. The high creatine kinase activity after cell fusion was of the MM type. No BB and MB activity was detected in these lines at any stage of differentiation. The difference in expression of creatine kinase isoenzymes seems not to affect the expression of other parameters of differentiation.

Changes in Serum Creatine Kinase Isoenzyme Activities after Surgical Procedures and Cardioversion

Serum activities of creatine kinase (CK) and its isoenzymes were monitored before and 16 to 20 hours after a variety of surgical procedures and cardioversion. Changes in total CK and CK MM activities in the surgical patients were consistent with the extent of trauma; changes in these activities in the cardioversion patients were more variable, ranging from -2 to 1829 U/l, and were unrelated to the applied electrical force. CK MB activity was unchanged after cystoscopy but rose moderately in 60% of patients after cholecystectomy, in 43% of patients requiring only implantation of a new pacemaker box, and in 87% of patients after implantation of an entire pacemaker system. No increase exceeded 6U/l. Fifty per cent of patients requiring cardioversion showed rises; the maximum value was 40.9 U/l.

Kreatinkinase und Kreatinkinase-Isoenzym MB: Erfahrungen mit der neuen Optimierten Methode mit N-Acetylcystein als Aktivator bei Gesunden und bei akutem Myokardinfarkt

Preliminary results are reported for the determination of creatine kinase and its isoenzyme MB in healthy individuals and in patients with acute, transmural myocardial infarct, using N-acetyl cysteine as the activator of the enzyme. In healthy individuals, the upper normal limit for creatine kinase activity was 54 U/l; the decision level for the presence of creatine kinase MB activity 9 U/l. The limiting values were only slightly different from those for the GSH-activated creatine kinase, and the results with the old and new methods showed a linear relationship with a slope of 1.0. The differences in the activation of creatine kinase MM by GSH and by N-acetyl cysteine are discussed; the activities obtained for creatine kinase and creatine kinase-MB by the GSH-activation method cannot simply be recalculated to give the appropriate values of the N-acetyl cysteine activation method.

Serum CK-KB Kinetics in Acute Myocardial Infarction and After Coronary Bypass Operations

Serum creatine kinase (CK) isoenzyme MB and total CK activity concentrations in 11 patients with acute myocardial infarction (AMI) were compared with the corresponding enzyme activities in 25 patients after coronary bypass surgery, not complicated clinically by AMI. Peak CK-MB occurred 2 +/- 0 (mean +/- SEM) hours after the end of surgery (mean duration of operation 6 hours), but 17 +/- 1 hours from the onset of symptoms in AMI. The plasma half"life for CK-MB was 11 +/- 1 hours under both conditions. Peak total CK was found after about 20 hours in both series of patients. Total CK half-life was 17 +/- 2 hours in AMI, but 30 +/- 3 hours following surgery. CK kinetics were thus different in these two situations, indicating different mechanisms for the elevations of serum CK-MB activity. In conclusion, the time course for the transient CK-MB elevation following bypass surgery should be considered in the diagnosis of peri operative infarction.

A Biochemical and Clinical Comparison of two Commercially Available Creatine Kinase Iso-Enzyme MB Assay Kits Suitable for use in the Routine Medical Laboratory

Two methods for the measurement of plasma creatine kinase MB (CK-MB) activity were compared for analytical performance, cost, practicality, and diagnostic correlation with clinical and electrocardiographic findings in patients admitted to the coronary care unit of a district general hospital. The methods were column chromatography and immunoinhibition. Both methods were found acceptable, and the method to be adopted would depend on the staff arrangements and resources available in the laboratory.

Relative merits of two electrophoretic and two column-chromatographic kets for determining serum creatine kinase isoenzyme MB activity.

Prospective analysis (by use of commercially available kits) of 339 validated admission specimens from patients consecutively admitted to a cardiac monitoring unit revealed sensitivities of 68 and 63% for two electrophoretic assays (Bioware and Helena) and up to 73 and 77% for two chromatographic assays (Roche and Worthington). Specificities were 94.8, 96,6, 90.2, and 89.7% and efficiencies were 90.2, 90.7, 87.0, and 87.0, respectively. Although these results differ from early reports, they agree well with several recent studies. However, 86 (25%) of the specimens gave at least one discrepant result based on clinical evaluation of the patients, and 68 (20%) gave at least one discrepant result between methods.

Increased creatine kinase isoenzyme MB values in patients without myocardial infarct.

Six of 13 randomly selected patients in a medical intensive-care unit with above-normal creatine kinase MB activities had diagnoses other than myocardial infarction. These data, which indicate the need for further study, were obtained during evaluation of a commercially available column procedure (Biodynamics/bmc).

Heart type creatine kinase isoenzyme (CK MB) in acute cerebral disorders.

Heart type creatine kinase isoenzyme (CK MB) was detected in the serum in 23 out of 53 patients (43%) with acute cerebrovascular, traumatic, or infectious brain damage. Electrocardiogram disclosed abnormalities suggestive of acute myocardial injury in 15 of these 23 patients. Eleven of them also showed increased LD1 activity. Subendocardial haemorrhage was detected in 3 out of 8 necropsied patients with serum CK MB activity. Among those 30 patients in whom no CK MB activity was found electrocardiographic abnormalities suggestive of acute myocardial injury were observed in 2 and increased LD1 was seen in 4 cases. The mortality was higher if either CK MB isoenzyme or electrocardiographic abnormalities suggestive of acute myocardial injury were present, compared with the patients lacking these signs (P less than 0.01). Present findings suggest that acute brain damage may secondarily cause myocardial damage more often than has been believed before. Results also indicate that a combination of acute brain damage and acute myocardial injury often indicated a poor prognosis.

Evaluation of myocardial damage during coronary artery grafting with serial determinations of serum CPK MB isoenzyme

Serial determinations of creatine phosphokinase isoenzymes (CPK) were made during the operative period and the first postoperative week in 60 patients undergoing coronary artery bypass surgery. Electrocardiograms (ECG) and serum levels of glutamic oxaloacetic transaminase (SGOT) and lactic dehydrogenase (LDH) were also evaluated. All patients had increased CPK MB activity which first became detectable during the operative period. The CPK MB curves usually showed a peak during the first postoperative hours and then a rapid decay. Some curves, however, showed a different profile with a prolonged liberation of CPK MB. This type of curve was more frequent in patients with electrical signs of necrosis or ischemic injury. In this group, the total amount of CPK MB released was greater than that in patients with unchanged ECG tracings (p less than 0.05). A mean curve of CPK MB activity was calculated for the patients without electric and/or enzymatic signs of myocardial injury. Serum CPK MB determination is a useful technique for identifying perioperative myocardial infarction (MI) and the time sequence of its occurrence. The appearance of this isoenzyme in every patient undergoing coronary surgery is an interesting finding, and it significance needs to be clarified.

Improved column method for separating lactate dehydrogenase isoenzymes 1 and 2.

Lactate dehydrogenase (LD) isoenzymes 1 and 2 in human serum were separated on a column of diethylaminoethyl-Sephadex. Samples layered on mini-columns were eluted with buffered sodium chloride (100, 150, and 200 mmol/liter). Lactate dehydrogenase activity in column effluents was measured by the Wacker method, and their isoenzyme content was evaluated by electrophoresis on polyacrylamide gel. Results for column-fractionated LD-1 and LD-2 were expressed in two ways: LD-1/LD-2 ratios and total LD-1 + LD-2 activities. The former is a more specific indicator of myocardial infarction than the latter. Sera from 10 patients with acute myocardial infarction (increased creatine kinease isoenzyme MB activity) exhibited ratios in the range of 0.92 to 1.56, ratios for 10 patients without heart disease (normal creatine kinase MB) ranged from 0.33 to 0.69.

Serum creatine kinase isoenzymes in progressive muscular dystrophy.

Creatine kinase isoenzymes in sera and muscle biopsies obtained from 50 controls, 72 patients with progressive muscular dystrophy (PMD), 68 patients with other neuromuscular disorders, 17 carriers of Duchenne-type PMD and 15 patients with myocardial infarction were studied. MB isoenzyme was detected in the sera of 58 patients with PMD and 56 out of 61 muscle biopsies. The MB activity varied between 4 and 400 IU/1 or 3.4--22% of total activity. The MB activity was demonstrated in a considerably smaller number of cases with polymyositis, dystrophic myotonia and Kugelberg-Welander disease. The MB isoenzyme in sera of PMD persisted for many years. It is admitted that the MB isoenzyme in the serum of patients with PMD originates chiefly from skeletal muscle.

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity activity kinetics and diagnostic significance in myocardial infarction

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intraserial C.V. of 2.0–12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6—25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.

Improved separation of creatine kinase cardiac isoenzyme in serum by batch fractionation.

I describe a simple, single-tube batch fractionation procedure for separating MM and MB isoenzymes of creatine kinase on a macroporous strong anion exchanger (AG MP-1, Bio-Rad Laboratories). The isoenzymes can be separated in less than 3 min, with a resulting dilution of the serum with no more than an equal volume of buffer. Without sample concentration or spectrofluorometric measurement, the procedure detects 4 U of MB isoenzyme per liter. Sensitivity is limited by the sensitivity and precision of the method of measurement. The CV for the fractionation can be held to less than 4.0% at 65 U of MB per liter. Current fractionation methods are compared to the proposed procedure. With use of a discrete analyzer (Du Pont aca) the mean MB activity in a population free of heart disease was 3.2 +/- 3.0 U/liter (range, 0 to 8 U/liter). The kinetics and stability of isolated isoenzymes are reported, indicating that advisability of storing or pre-incubating samples with mercaptoethanol.

Rapid and quantitative immunological method for the determination of creatine kinase isoenzyme MB activity in serum

Rapid and quantitative immunological method for the determination of creatine kinase isoenzyme MB activity in serum

New Manual and Automated Method for Determining Activity of Creatine Kinase Isoenzyme MB, by Use of Dithiothreitol: Clinical Applications

The method is based on the selective activating capacity of dithiothreitol on creatine kinase isoenzyme MB, after isoenzyme MM is activated by glutathione. Isolated isoenzymes MM and MB of human and canine origin were assayed individually and in mixtures of known activities. When glutathione was present in the assay medium the activity of each isoenzyme could be measured individually, but glutathione did not activate isoenzyme MB if it was present in a mixture with MM. Dithiothreitol, added to the serum before assay, activated the isoenzyme MB in the mixture. Values for MB activities obtained for isolated isoenzyme MB and for the isoenzyme mixture after dithiothreitol was added averaged 110 and 111 U/liter, respectively (r = 0.998; y = 1.007 x + 0.298; n = 10). In the serum of 40 patients with documented acute transmural myocardial infarction, the mean proportion of isoenzyme MB activity measured in this way was 5.5% (coefficient of variation, 7.7%). Isoenzyme MB activities measured by use of dithiothreitol compared well with those obtained by conventional electrophoresis/spectrophotometry (r = 0.998; y = 1.09x -0.65) and spectrofluorometry (r = 0.996; y = 1.10 x + 0.80). The assay of MB activity by the dithiothreitol method was automated, by use of an Abbott Bichromatic Analyser and a Calbiochem Super-Stat Pack Kit. In 60 isoenzyme MB determinations the manual and automated method correlated well (r = 0.990; y = 1.0x -1.36). The simplicity of isoenzyme MB determination by use of dithiothreitol and its ease of automation allow routine monitoring of the isoenzyme activity in patients with ischemic heart disease.

Specificity of elevated serum MB creatine phosphokinase activity in the diagnosis of acute myocardial infarction

Creatine phosphokinase (CPK) isoenzyme determinations are useful in the diagnosis of myocardial infarction. However, until suitably sensitive and precise quantitative procedures became available, the diagnostic specificity of serum CPK isoenzyme elevations could not be thoroughly examined. In this study an assay procedure capable of accurately determining activity of individual CPK isoenzymes even in serum samples with normal total CPK activity was employed to obtain two types of information. First, CPK isoenzyme profiles were examined in extracts of a spectrum of human tissues obtained at operation to determine whether the isoenzyme associated with myocardium is present in other human tissues in quantities sufficient to produce increased activity in serum. In addition, CPK isoenzymes were analyzed quantitatively in serial serum samples from 50 hospitalized control subjects, 100 patients with acute myocardial infarction, 100 patients undergoing noncardiac surgery and 50 patients undergoing cardiac catheterization to determine whether insult to tissues other than the heart is associated with increased “myocardial” CPK isoenzyme activity in serum. Results from analyses of tissue extracts indicated that myocardium is the only tissue surveyed containing sufficient MB CPK to account for substantial increases in serum MB activity. Results from analyses of serial serum samples indicated that MB CPK activity levels are consistently elevated after myocardial infarction, averaging 0.089 IU/ml. However, after cardiac catheterization or noncardiac surgery peak serum MB activity remains low, averaging only 0.004 IU/ml despite marked elevations in total serum CPK activity. Thus, elevated serum MB CPK activity is a highly specific as well as sensitive criterion of myocardial injury.

Chromatographic and Electrophoretic Separation of Creatine Kinase Isoenzymes Compared

We compared two techniques for separating and evaluating serum creatine kinase isoenzymes--fluorometric agarose electrophoresis and Sephadex chromatography--in 50 patients, 25 of whom had confirmed acute myocardial infarction. In every case isoenzyme MB (heart isoenzyme) was detected with equal sensitivity by either procedure. Evidently, only the presence or absence of MB is clinically significant; none of the 25 patients without infarction had detectable MB activity in their serum. Columns connected to a continuous-flow sample line for analyses of the eluting stream without further modification produced satisfactory results.