Effects of therapeutic coronary reperfusion on aspartate aminotransferase isoenzymes in sera of patients with acute myocardial infarction

We examined the kinetics of the catalytic activities of aspartate aminotransferase (AST, EC 2.6.1.1) isoenzymes in serum of 28 patients with myocardial infarction who were to receive either intracoronary urokinase--reperfusion angiographically proved--or conventional therapy (control group). Cytosolic (soluble) AST (s-AST) activity in serum increased rapidly immediately after recanalization, reaching a maximum 12 h after the onset of infarction. In the control group, this peak was reached 28 h after the onset (P less than 0.001). Peak s-AST activity was similar in the two groups. Peak activity and peak time for mitochondrial AST (m-AST) were the same for the two groups of patients; intervention that affects myocardial perfusion caused only a slight additional increase in m-AST activity in the early post-infarct period. There may be advantages to measuring m-AST, which is briefly influenced by reperfusion, instead of the usual cytosolic enzymes for assessment of myocardial damage in patients with myocardial infarction treated with thrombolytic therapy.     

A homogeneous assay system of aspartate aminotransferase iso-enzymes using proteases and application for clinical evaluation of myocardial infarction.

We designed a rapid, homogeneous assay for human aspartate aminotransferase (AST) isoenzymes, by a selective proteolysis of soluble AST (s-AST), using chymotrypsin and protease 401. The linearity of mitochondrial (m-AST) was elongated up to 4000 U/l. m-AST values from the human liver, and determined by a homogeneous assay using protease 401 or chymotrypsin, were relative to those obtained using an immunoprecipitation method. In perioperative patients or those with an acute myocardial infarction, the peaks of s-AST and m-AST values were noted 13 h and at 57 h after ictus, respectively, whereas the peak of ratio between was seen 6 h after ictus. In the case of Budd-Chiari syndrome, the maximum levels of the two AST activities were evident 14 days after hospitalization and the peak of ratio between them was seen after 7 days. We propose that this homogeneous assay can serve as a diagnostic tool for early phase detection of myocardial infarction and of Budd-Chiari syndrome.     

Changes in mass and catalytic activity concentrations of aspartate aminotransferase isoenzymes in serum after a myocardial infarction

We used an RIA and inhibition of enzyme activity to monitor the changes in mass and catalytic concentrations of the aspartate aminotransferase (EC 2.6.1.1;AST) isoenzymes in serum after myocardial infarction. Cytosolic (c-AST) and mitochondrial (m-AST) forms of AST were present in sera from all 38 of our patients. Although the immunological and catalytic concentrations of both isoenzymes correlated well with the size of the infarct, c-AST gave a better measure than did m-AST. About 20% of the total enzyme activity at peak activity was from the mitochondrial isoenzyme. Both isoenzyme activities peak at very nearly the same time, but m-AST has the longer half-life. Immunological evidence of the mitochondrial isoenzyme can be detected in serum for at least eight days after the infarct. The presence of left ventricular failure produces greater serum isoenzyme activities than in those without failure.     

Prognostic value of mitochondrial aspartate aminotransferase in acute myocardial infarction

In 112 prospectively selected patients suffering from acute myocardial infarction (AMI), the serum CK, CK-MB, LD, HBD, AST and m-AST were determined from the time of admission to hospital and every 12 hours for three days in succession. Sixteen of the enrolled patients died due to complications which arose within the first four days of hospitalization while the rest had a favourable outcome. All enzyme activities were determined at 37 degrees C using routine methods; m-AST was measured using an immunochemical method. The statistical analysis of the results demonstrated that 12 hours after admission, serum m-AST and m-AST/AST ratio were significantly higher in the group of non-survivors compared with patients with a favourable prognosis. No significant differences in CK-MB were observed between survivors and non-survivors during the entire period. True and false positive rates were calculated for these and the other enzymes. An optimum decision level of 34 IU/L was chosen for m-AST and 10% for the m-AST/AST ratio. This gave a percentage of correctly classified patients, after 12 and 24 hours, of 74.9% and 91.9%, respectively. In conclusion, the immunochemical determination of m-AST in patients with AMI seems to be an early prognostic index which is able to distinguish patients with unfavourable outcome.     

Serum enzymes in acute myocardial infarction after intracoronary thrombolysis

Serum kinetics of total creatine kinase (CK), CK-MB isoenzyme, aspartate aminotransferase (AST), lactate dehydrogenase (LD) and alpha-hydroxybutyrate dehydrogenase (HBD) activities were studied in twenty patients with acute myocardial infarction randomly assigned to receive either intracoronary urokinase (group A) or conventional (control) therapy (group B). The temporal characteristics of enzyme changes described were the time lag from onset of chest pain until maximum catalytic concentration value, the rate at which enzymes are released into blood, the peak value of the serum enzyme curves and (d) the fractional disappearance rate (Kd) for each enzyme considered. Thrombolytic treatment induced earlier peak times in group A: for CK, 10.8 vs 27.0 h, for CK-MB, 10.4 vs 23.1, for AST, 13.9 vs 31.3, for LD, 24.4 vs 49.1, and for HBD, 20.5 vs 48.5 (for all enzymes, p less than 0.001). The maximal rate of release for the enzymes was at least twofold greater in group A. Enzyme peak activities and Kd were not significantly different between the groups. The most significant discrimination between the two groups was obtained with AST peak time (Hartz overlap index (Oi) = 0.11) and CK-MB peak time (Oi = 0.12).     

Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase in sera of patients after myocardial infarction

Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase (AST) were studied in the sera of 42 patients following acute myocardial infarction and compared to creatine kinase (CK), lactate dehydrogenase (LDH) and alanine aminotransferase (ALT). Mitochondrial AST( ASTm ) was detected in 93% (39/42) of patients. Maximum recorded ASTm activity was 59.5 +/- 8.8 U/l and was found 39.4 +/- 3.5 hours after the onset of symptoms (chest pain) of myocardial infarction. In contrast the maximum recorded cytoplasmic AST ( ASTc ) activity was greater (327 +/- 23 U/l) and it occurred earlier (33.5 +/- 2.2 hours) after onset of infarction compared to ASTm . ASTm correlated significantly (p less than 0.05) with ASTc , LDH and ALT but not with total CK or CK-MB. ASTc correlated significantly (p less than 0.05) with total CK, CK-MB and LDH but not ALT. Maximum recorded ASTm activity was significantly associated with the clinical assessment of left ventricular failure ( Killip classification) but not with ventricular arrhythmias. In a subset of 15 patients evaluated with invasive hemodynamic measurements of cardiac output and pulmonary capillary wedge pressure. ASTm correlated significantly (p less than 0.05) and better than CK-MB with the hemodynamic assessment of left ventricular dysfunction. Thus ASTSm can be readily identified in sera of patients after acute myocardial infarction and may be of value in the evaluation of patients with acute myocardial infarction.     

Differentiating muscle damage from myocardial injury by means of the serum creatine kinase (CK) isoenzyme MB mass measurement/total CK activity ratio

We immunoenzymometrically measured creatine kinase (CK) isoenzyme MB in extracts of myocardium and in homogenates of five different skeletal muscles. CK-MB concentrations in the former averaged 80.9 micrograms/g wet tissue; in the skeletal muscles it varied widely, being (e.g.) 25-fold greater in diaphragm than in psoas. CK-MB in skeletal muscles ranged from 0.9 to 44 ng/U of total CK; the mean for myocardium was 202 ng/U. In sera from 10 trauma and 36 burn patients without myocardial involvement, maximum ratios for CK-MB mass/total CK activity averaged 7 (SEM 1) ng/U and 18 (SEM 6) ng/U, respectively. Except for an infant (220 ng/U), the highest ratio we found for serum after muscular damage was 38 ng/U. In contrast, the mean maximum ratio determined in 23 cases of acute myocardial infarction exceeded 200 ng/U. Among seven determinations performed 8 to 32 h after onset of symptoms, each infarct patient demonstrated at least one ratio greater than or equal to 110 ng/U. Ratios observed after infarct were unrelated to treatment received during the acute phase. We propose a CK-MB/total CK ratio of 80 ng/U as the cutoff value for differentiating myocardial necrosis from muscular injury.     

Diagnosis of perioperative myocardial infarction by considering relationship of postoperative electrocardiogram changes and enzyme increases after coronary bypass operation

We report the results of enzyme determinations in sera from 88 patients, 65 of whom showed inconspicuous reconvalescence, 14 who had myocardial infarction within 24 h (MI 1) after bypass surgery, and nine with myocardial infarction between 24 and 48 h postoperatively (MI 2). We wanted to determine whether the consequent measurement of activities of total creatine kinase (CK), CK isoenzyme MB (CK-MB), lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, and aspartate aminotransferase, conducted as a part of routine laboratory diagnostics, provided meaningful information for diagnosing infarcts besides that obtained from the electrocardiogram. The postoperative mean values of the enzyme activities in blood were significantly different among the three groups; however, only a combined evaluation of CK and CK-MB by means of a discriminant analysis allowed the prediction of MI (sensitivity: MI 1 = 98.5%, MI 2 = 95.4%; specificity: MI 1 = 71.4%, MI 2 = 81.8%). CK greater than 600 U/L or CK-MB greater than 45 U/L supports the diagnosis of acute MI.     

Complexes of immunoglobulins A and G with aspartate aminotransferase isoenzymes in serum

We report the presence of complexes between aspartate aminotransferase (AST, EC 2.6.1.1) and immunoglobulin (Ig) in the serum of a patient suffering from lung cancer with metastasis to the liver. After fractionation of the serum by gel filtration, AST-Ig complexes (AST-IgA, AST-IgG) were demonstrated by counterimmunoelectrophoresis. Dissociating the complexes and recombining them with purified isoenzyme fractions, s-AST (cytoplasmic) and m-AST (mitochondrial), revealed that only s-AST binds to IgG, whereas IgA binds to both s-AST and m-AST. Although the association of AST with IgG has been reported, to our knowledge this is the first finding of both AST-IgA and AST-IgG complexes in a patient's serum. Serum AST-IgG complexes have been demonstrated in both healthy and diseased individuals; in the latter category, as reported here and by others, the liver is implicated.     

Serum isoforms of creatine kinase MM and MB in myocardial infarction. An appraisal of quantitative, clinical and pathophysiological information

Using an electrophoretic method, the changes in the catalytic activities of three CK-MM isoforms (MM1, MM2, MM3) and two CK-MB isoforms (MB1, MB2) in the serum of 13 patients with acute myocardial infarction (AMI) have been monitored for 3 days after the onset of chest pain. In post-AMI period, MM3 reaches a peak first, 17 h after infarction (394 U/l), followed by MB2 (17.3 h, 190 U/l), MB1 (20.6 h, 82 U/l), MM2 (28.7 h, 637 U/l), and MM1 (32 h, 780 U/l). According to their faster decay from circulation, MB2 and MM3 have higher fractional disappearance rates (-0.035 and -0.026 per hour, respectively). The MM3/MM1 activity ratio rises beyond the upper limit found in healthy subjects within about 3 h after onset of symptoms and peaks 9.3 h after AMI, even earlier than peaks of isoforms. These characteristics make the ratio an earlier and more sensitive indicator of acute enzyme release from necrotic myocardium.     

Release patterns of CK-MB and mitochondrial CK following myocardial ischaemia

Following myocardial damage as in acute myocardial infarction (AMI) or open heart surgery, the tissue damage might result in a release of mitochondrial CK (CK-MIT). The presence of this CK isoenzyme in serum may be detected after chromatographic separation of CK-activity on Sephacryl S-200. By combining chromatographic separation of CK-MB with immunologic inhibition of CK-M, both CK-MB and CK-MIT can be estimated in serum. Using this procedure changes in enzyme activities were studied in ten patients with AMI and twelve patients subjected to open heart surgery using cardioplegia. Following AMI CK-MB peaked about 24 h after onset of ischaemic symptoms. CK-MIT increased similarly and reached a plateau after 24 h where it remained during an additional 24-36 h. At peak CK-MB concentration, the corresponding CK-MIT activity was about 22% of the CK-MB activity. Following cardiac surgery there was a rapid release of CK-MB with a peak about 5 h after release of aortic cross-clamping, and with a simultaneous CK-MIT activity amounting to 19% of the CK-MB activity. In conclusion, CK-MIT is released into serum following myocardial ischaemia. Its appearance has time characteristics similar to that of other mitochondrial enzymes. The CK-B method does not specifically determine CK-B, but non-CK-M, which in cardiac ischaemia at peak serum CK-MB concentrations includes about 20% CK-MIT.     

Clinical assessment of specific enzyme immunoassay for the human cardiac myosin light chain II (MLC II) with use of monoclonal antibodies

A highly specific enzyme-linked "sandwich" immunoassay was developed for determining cardiac myosin light chain II (MLC II) in serum by using an anticardiac MLC II monoclonal antibody and a solid phase consisting of glass rods coated with another monoclonal antibody. We can detect as little as 0.2 ng of cardiac MLC II per assay. The measurable range of cardiac MLC II concentration in serum is 1 to 30 micrograms/L. The assay demonstrated no cross-reactivity with a skeletal muscle MLC within the measurable range. The mean coefficients of variation were 6.1% within assay and 5.1% between assay. The concentration of cardiac MLC II in sera from healthy subjects ranged from 0 to 4.0 micrograms/L (mean 0.75 micrograms/L and median 0 micrograms/L). The concentrations of cardiac MLC II in serum of patients with skeletal muscle disease due to various causes (n = 15) and patients with effort angina (n = 25), in general, were not significantly elevated above normal. In all patients with myocardial infarction, the concentrations of cardiac MLC II were over 4.0 micrograms/L at 12 h after onset. The mean (+/- 1 SD) peak concentration of cardiac MLC II was 16.2 (+/- 4.4) micrograms/L at 90 h (mean) after onset. On the 5th day, the cardiac MLC II concentrations in all patients with myocardial infarction were significantly elevated above normal; none showed abnormal MB-creatine kinase (CK-MB) activity at this time. Thus, the measurement of cardiac MLC II concentration in serum may be useful to provide a specific and sensitive diagnosis of myocardial necrosis at any time period following myocardial infarction.     

精浆天门冬氨酸氨基转移酶及其线粒体同工酶检测与精子膜功能完整性的关系

目的对精浆天门冬氨酸氨基转移酶(AST)及其线粒体同工酶(m-AST)的活性进行检测,并分析AST和m-AST活性与精子膜功能完整性的相关性。方法 122例精液标本,分别检测精浆AST和m-AST活性,用低渗肿胀-伊红Y结合试验(HOS-EY)检测精子头-尾膜完整性,用琥珀酸脱氢酶(SDH)染色法检测精子线粒体SDH,同时分析AST和m-AST活性与精子膜功能完整性的相关性。结果精浆AST与m-AST的活性分别为(238±125)U/L和(147±79)U/L,两者呈明显正相关性(r=0.740,P=0.000)。AST和m-AST活性均与(Ⅰ+Ⅱ+Ⅲ)型精子呈明显正相关性(r=0.443,P=0.013;r=0.691,P=0.000)。AST和m-AST活性均与Ⅳ型精子呈明显负相关性(r=-0.439,P=0.013;r=-0.689,P=0.000)。AST活性与精子SDH阳性率无明显相关性(r=-0.187,P=0.313),而m-AST活性与精子SDH阳性率呈明显负相关性(r=-0.471,P=0.007)。结论精浆AST和m-AST活性与精子膜功能完整性具有相关性,而m-AST活性检测更适合评价精子膜受损程度以及精子线粒体受损状况。     

Determination of aspartate aminotransferase isoenzymes in hepatic diseases — preliminary findings

The study sought to establish a relationship between the AST isoenzyme levels in serum and degree of hepatic damage, by using a new and simple immunochemical method for the differential determination of the isoenzymes. Sixty-nine patients with various hepatic diseases were studied.During hepatic damage, cytoplasmic isoenzyme (s-AST) is found in greater quantities than mitochondria! isoenzyme (m-AST), but the m-AST level increases to a greater extent in acute liver diseases. However, m-AST in alcoholic hepatitis is higher than expected from the total AST (t-AST) values. The ratio of m-AST to t-AST seems to discriminate alcoholic hepatitis from other liver diseases.     

Changes in the ratio of lactate dehydrogenase isoenzymes 1 and 2 during the first day after acute myocardial infarction

It is known that the ratio of isoenzyme 1 to total lactate dehydrogenase (LD, EC 1.1.1.27) in serum is increased in all patients with acute myocardial infarction within 24 h of the infarct. We now show that the LD-1/LD-2 ratio for serum more promptly indicates acute myocardial infarction, being for most patients equivalent to measurement of creatine kinase (EC 2.7.3.2) isoenzyme 2 (CK-2, CK-MB) in serum. Of 128 patients with a confirmed diagnosis of myocardial infarction, 66 had normal values for all "cardiac" enzymes at the time of admission, but greater than 75% of them showed a parallel increase in values for CK-2 and the LD-1/LD-2 ratio. Of the 26 patients who had one or more abnormal values for cardiac enzymes on admission, 95% showed a parallel increase in CK-2 and the LD-1/LD-2 ratio, the median time for the beginning of these changes being 9 h from the onset of chest pain. The remaining 36 patients were excluded from the study because CK-2 decreased after admission or because the time of onset of chest pain was uncertain.     

酶抑制法测定m-AST试剂性能评价及其在肝病中的意义

目的评价酶抑制法测定天门冬氨酸氨基转移酶（AST）线粒体同工酶（m—AST）活性的性能,并探讨m—AST在肝脏疾病中的临床价值。方法采用酶抑制法检测m—AST活性[即采用蛋白酶完全抑制AST细胞质同工酶（c—AST）的活性,然后用速率法进行检测],并与免疫抑制法比较。采用酶抑制法检测259例肝病患者（包括急性肝炎43例、慢性病毒性肝炎95例、肝衰竭20例、重型肝炎11例、肝硬化代偿期40例、肝硬化失代偿期9例、原发性肝癌41例）及220名健康体检者（正常对照组）m—AST活性,并与AST比较。结果酶抑制法批内变异系数（CV）为0．59％～2．23％,批间CV为5．24％～6．23％;回收率为101．6％～108．0％,平均为104．97％;线性方程Y=0．997X一1．51,r=0．9999,m—AST活性在450U／L内线性良好;可完全抑制1500U／L的c—AST活性;与免疫抑制法结果呈高度正相关（r=0．9998）;溶血对m—AST检测结果干扰较大;以95％可信区间（孟±1．96s）初步确定m—AST参考区间男性为3．1～9．5U／L,女性为2．5～8．7U／L。肝病患者m—AST活性均高于正常对照组（P〈0．05）,并与AST呈正相关。正常对照组m—AST／AST比值为0．30±0．07,肝病患者m—AST／AST比值均低于正常对照组（P〈0．05）,但变化不如m—AST活性明显。结论酶抑制法测定m．AST活性自动化程度高,结果准确可靠,重复性好,线性范围宽。m—AST活性能反映肝细胞损伤的严重程度,对肝脏疾病的临床分类和预后具有重要价值。     

Predictive value of serum enzyme determinations in acute myocardial infarction

The prognostic significance of serum enzyme measurements in acute myocardial infarction was studied in 146 patients hospitalized shortly after the attack. Creatine kinase (CK), CK-MB, aspartate aminotransferase (ASAT) and lactate dehydrogenase (LDH) were serially determined every four hours during the first three days following admission.Peak enzyme levels correlated well with the cumulated CK release (r = 0.95, 0.74, 0.70 for CK, ASAT and LDH respectively). Among all enzyme measurements, LDH levels determined when CK reached its peak value provided the best discrimination between acute phase survivors (15 days) and non-survivors. LDH was also the best measurement for identifying patients with ventricular impairment. LDH and ASAT peak levels were more powerful predictors of the patient's risk than CK peak levels. CK levels determined later in the course of myocardial infarction were more discriminant, indicating prolonged CK elevation in non-survivors. There was no significant difference in CK-MB levels, nor in cumulated CK-MB amounts for survivors and non-survivors.It is concluded that serum LDH activity is a better predictor of the short term evolution of myocardial infarction than CK levels or infarct size estimations from serial CK determinations.     

IgA-CK-BB complex with CK-MB electrophoretic mobility can lead to erroneous diagnosis of acute myocardial infarction

This patient, on admission, presented with a tentative diagnosis of myocardial infarction: the electrocardiogram showed a nonspecific ST-segment and T-wave abnormalities, and total creatine kinase (CK; EC 2.7.3.2) activity was slightly increased (238 U/L). However, a high electrophoretic value for CK-MB (50% of total CK activity) and the electrophoretic pattern of lactate dehydrogenase (EC 1.1.1.27) isoenzymes ruled out myocardial infarction. The isoenzyme migrating as CK-MB was found later to contain no immunologically normal CK-M subunits, and it was bound to IgA. A mixture of the patient's serum and a human serum control containing all CK isoenzymes showed altered electrophoretic mobility only for CK-BB, indicating that the patient's serum contained antibodies to the B unit of CK. Elution from a Sephadex G-200 column showed that the peak at which most of the anodic CK was eluted corresponded to a molecular mass of approximately 200 kDa. Evidently this atypical isoenzyme was an IgA-CK-BB complex. Because this macro CK type 1 can mimic CK-MB, it may therefore be a source of confusion.     

Changes in serum CK-MB mass after coronary artery bypass surgery

We assessed the release of creatine kinase MB as both mass and activity during the postoperative period following cardiac surgery. CK-MB mass was determined by enzyme immunoassay using reagents obtained from Hybritech. CK-MB activity was determined both by agarose electrophoresis and by an immunochemical method. Fifty-five patients who underwent coronary artery bypass surgery and 52 control subjects who had orthopedic surgery were selected for study. Serial serum samples were collected following surgery and total LD, CK, AST, LD-1, CK-MB mass, and CK-MB activity determined. Results were compared to each other and to surgical parameters. All patients exhibited significant CK-MB mass and activity after surgery and peak serum levels were 6-94 micrograms/L and 12-84 U/L, respectively. CK-MB mass correlated with CK-MB activity on paired samples (r = 0.94). Total AST and CK activities correlated with CK-MB mass (r = 0.60, and 0.63, respectively). Peak levels of CK-MB mass correlated significantly with peak MB activity (r = 0.88), peak LD-1 (r = 0.62), peak AST (r = 0.71), and time on pump (r = 0.54). Similar correlations were also seen between peak CK-MB activity and these parameters. No relationship could be identified between extent of CK-MB mass release and number of grafts, degree of hypothermia, or minimum PaO2. The time course of CK-MB mass release exhibited 85% concordance with CK-MB activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

罗氏Cobas8000全自动生化分析仪检测心肌酶谱的性能评价

目的对在罗氏公司Cobas8000型全自动生化分析仪上检测的心肌酶谱:天门冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH)、肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)的分析性能进行评价。方法参考美国临床和实验室标准化协会性能评价方法和相关报道,并根据临床需求和实际要求,对罗氏公司Cobas8000型全自动生化分析仪测定血清心肌酶谱的准确度、精密度、线性范围、生物参考区间和最大稀释倍数5项分析性能进行验证和评价,并与强生公司Vitro5600型分析仪进行方法学比对。结果罗氏Cobas8000分析仪对心肌酶谱的检测准确度较好,各项指标的相对偏倚均小于允许总误差的1/2,符合美国临床实验室改进修正法案(CLIA′88)的指标要求。精密度验证结果显示批内变异系数和不同批次之间的检测标本变异系数分别小于允许总误差的1/4和1/3。线性回归方程的斜率在0.998~1.017,r 2均≥0.995。AST、LDH、CK、CK-MB的临床可报告范围分别为2~700 U/L、10~1000 U/L、7~2000 U/L、3~2000 U/L。参考范围验证除LDH有一个值超出该参考区间外,其他结果均在参考范围内。高浓度的标本可经稀释后再行测定,测定结果表明4项测定指标的相对偏差在允许误差范围内,具有较高的临床参考价值。实验室内结果比对,4个项目比对结果均符合CLIA′881/2允许偏倚,与Vitro5600型分析仪具有良好的一致性。结论罗氏Cobas8000型全自动生化分析仪检测心肌酶谱的主要分析性能均符合厂商声明的性能和有关的质量要求,检测结果准确性较高、可靠性较好,临床参考价值较高,故可满足临床需求。