Multicenter evaluation of a second-generation assay for cardiac troponin T

Abstract We report on the evaluation of the second-generation assay for cardiac troponin T (cTnT) on the Enzymun®system. This new assay is completely specific for the cardiac isoform of TnT, utilizing two cardiospecific monoclonal antibodies. The assay time is reduced to 45 min. The interassay precision shows a median CV of 5.5%; 20% interassay CV was found between 0.05 and 0.1 μg/L. The cardiosensitivity of the second-generation cTnT assay in patients with ischemic myocardial injury appears equivalent when compared with the first-generation assay. We found no falsely positive results in patients with skeletal muscle damage including multitraumas, surgery patients, and marathon runners who showed highly increased values with the unspecific first-generation assay. In Duchenne disease cTnT was still increased, but to a much lower extent. cTnT remains increased in renal failure, but to a lesser degree than with the first-generation assay. The cause of this increase remains unclear. Although a cross-reactivity of skeletal muscle TnT in the second-generation assay could be excluded by our findings, minor myocardial damage or expression of the cardiac isoform of TnT in regenerating muscles cannot be ruled out in those cases with apparently falsely increased cTnT values. The second-generation cTnT assay is a step forward in the combination of cardiosensitivity and cardiospecificity in biochemical markers for diagnosis of heart disease.

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Improved troponin T ELISA specific for cardiac troponin T isoform: assay development and analytical and clinical validation

Clinical Chemistry ◽

10.1093/clinchem/43.3.458 ◽

1997 ◽

Vol 43 (3) ◽

pp. 458-466 ◽

Cited By ~ 199

Author(s):

Margit Müller-Bardorff ◽

Klaus Hallermayer ◽

Angelika Schröder ◽

Christoph Ebert ◽

Anneliese Borgya ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Injury ◽

First Generation ◽

Troponin T ◽

Myocardial Damage ◽

Cross Reactivity ◽

Clinical Validation ◽

Marathon Runners ◽

Positive Results ◽

Reactive Antibody

Abstract The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients with severe skeletal muscle injury. Therefore, a cardiac-specific second-generation troponin T ELISA (TnT 2) was developed, in which the cross-reactive antibody 1B10 has been replaced by a high-affinity cardiac-specific antibody M11.7. No cross-reactivity of TnT 2 was observed with purified skeletal muscle troponin T (1000 μg/L) or in test samples from 43 marathon runners and 24 patients with rhabdomyolysis and highly increased creatine kinase. TnT 2 was increased >0.2 μg/L in 5 of 40 patients with renal failure and in 4 of 20 muscular dystrophy patients. The detection limit is 0.012 μg/L. Day-to-day imprecision (CV) within the range 0.19–14.89 μg/L was <5.8%. In 4955 patients without myocardial damage, 99.6% had TnT <0.10 μg/L. Assay comparison (TnT 1 vs TnT 2) over the whole concentration range (i.e., in 323 samples from AMI-suspected patients) showed a slope, intercept, and standard error of estimate (Sey) of 1.18, 0.01 μg/L, and 0.81 μg/L, respectively.

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Cardiac troponin I, cardiac troponin T, and creatine kinase MB in dialysis patients without ischemic heart disease: evidence of cardiac troponin T expression in skeletal muscle

Clinical Chemistry ◽

10.1093/clinchem/43.6.976 ◽

1997 ◽

Vol 43 (6) ◽

pp. 976-982 ◽

Cited By ~ 133

Author(s):

Mary D McLaurin ◽

Fred S Apple ◽

Ellen M Voss ◽

Charles A Herzog ◽

Scott W Sharkey

Keyword(s):

Skeletal Muscle ◽

Heart Disease ◽

Ischemic Heart Disease ◽

Cardiac Troponin ◽

First Generation ◽

Troponin T ◽

Ischemic Heart ◽

Cardiac Troponin T ◽

Dialysis Patients ◽

Acute Ischemic Heart Disease

Abstract Serum cardiac troponin T (cTnT) concentrations are frequently increased in chronic dialysis patients as measured by the first-generation ELISA immunoassay, as is creatine kinase (CK) MB mass in the absence of acute ischemic heart disease. We designed this study to compare four serum markers of myocardial injury [CK-MB mass, first-generation ELISA cTnT, second-generation Enzymun cTnT, and cardiac troponin I (cTnI)] in dialysis patients without acute ischemic heart disease. We also evaluated skeletal muscle from dialysis patients as a potential source of serum cTnT. No patients in the clinical evaluation group (n = 24) studied by history and by physical examination, electrocardiography, and two-dimensional echocardiography had evidence of ischemic heart disease. Biochemical markers were measured in serial predialysis blood samples with specific monoclonal antibody-based immunoassays. For several patients at least one sample measured above the upper reference limit: CK-MB, 7 of 24 (30%); ELISA cTnT, 17 of 24 (71%); Enzymun cTnT, 3 of 18 (17%); and cTnI, 1 of 24 (4%). In a separate group of dialysis patients (n = 5), expression of cTnT, but not cTnI, was demonstrated by Western blot analysis in 4 of 5 skeletal muscle biopsies. Chronic dialysis patients without acute ischemic heart disease frequently had increased serum CK-MB and cTnT. The specificity of the second-generation cTnT (Enzymun) assay was improved over that of the first-generation (ELISA) assay; cTnI was the most specific of the currently available biochemical markers. cTnT, but not cTnI, was expressed in the skeletal muscle of dialysis patients.

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Cardiac troponin T isoforms expressed in renal diseased skeletal muscle will not cause false-positive results by the second generation cardiac troponin T assay by Boehringer Mannheim

Clinical Chemistry ◽

10.1093/clinchem/44.9.1919 ◽

1998 ◽

Vol 44 (9) ◽

pp. 1919-1924 ◽

Cited By ~ 129

Author(s):

Vincent Ricchiuti ◽

Ellen M Voss ◽

Arthur Ney ◽

Mark Odland ◽

Page A W Anderson ◽

...

Keyword(s):

Skeletal Muscle ◽

Molecular Mass ◽

Cardiac Troponin ◽

Second Generation ◽

Troponin T ◽

Chronic Renal Disease ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Cardiac Troponin T ◽

Muscle Biopsies

Abstract The purpose of this study was to determine whether the two monoclonal anti-cardiac troponin T (cTnT) antibodies (MAbs) used in the second generation cTnT assay by Boehringer Mannheim (BM, capture Ab, M11.7; detection Ab, M7) would detect cTnT isoforms expressed in human skeletal muscle in response to chronic renal disease (CRD). cTnT expression was examined in skeletal muscle biopsies obtained from 45 CRD patients, as well as nondiseased human heart (n = 3) and skeletal muscle (n = 3). cTnT proteins were resolved by modified 7.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose, and probed with the following anti-cTnT MAbs: M11.7; M7; JS-2, Lakeland Biomedical; and 13–11, Duke University. All four antibodies detected the cTnT isoforms (Ta, Te) expressed in human myocardium. In 20 of 45 skeletal muscle biopsies, MAb M11.7 recognized its epitope in one to three proteins, molecular mass 34–36 kDa, designated Te, Td, and Tc; the strongest signal was that of Te. The same proteins were recognized by MAbs JS-2 and 13–11. The BM M7 antibody did not detect the cTnT isoforms in the molecular mass range of 34–36 kDa. However, MAb M7 did detect a cTnT isoform, molecular mass 39 kDa, in 2 of 45 biopsies. This isoform had an electrophoretic mobility similar to the predominant heart cTnT isoform, Ta. We conclude that cTnT isoforms are expressed in the skeletal muscle of CRD patients. However, given the epitopes recognized by the BM MAbs M7 and M11.7 and the variable presence of these cTnT isoforms in skeletal muscle, the second generation BM cTnT assay will not detect these isoforms if they are released from skeletal muscle into the circulation.

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Analytical validation of a high-sensitivity cardiac troponin T assay in horses

Journal of Veterinary Diagnostic Investigation ◽

10.1177/1040638715593601 ◽

2015 ◽

Vol 27 (4) ◽

pp. 504-509 ◽

Cited By ~ 5

Author(s):

Nicky Van Der Vekens ◽

Marie-Astrid van Dievoet ◽

Hendrik De Puydt ◽

Annelies Decloedt ◽

Sofie Ven ◽

...

Keyword(s):

Cardiac Troponin ◽

Troponin T ◽

Myocardial Damage ◽

High Sensitivity ◽

Cross Reactivity ◽

Cardiac Troponin T ◽

Plasma Samples ◽

Analytical Validation ◽

Serum Samples ◽

Coefficients Of Variation

Although cardiac troponin T (cTnT) assays have been used to detect myocardial damage in horses, a cTnT assay has not been analytically validated, to our knowledge. The aims of this study were to estimate the precision of a high-sensitivity cTnT assay in horses and determine the effect of hemolysis on the measured cTnT concentration. Serum samples from horses were mixed in 3 different pools. Pool 1 consisted of samples from 3 healthy horses, pool 2 from 6 horses with heart failure or atypical myopathy, and pool 3 from 10 horses with atypical myopathy. The within- and between-run coefficients of variation were determined for each pool. Pools 2 and 3 were diluted to estimate linearity. To study the influence of sample hemolysis, serum was collected from 4 horses with a high cTnT concentration, in which hemolysis was mechanically induced. In addition, ethylenediamine tetra-acetic acid blood tubes were collected from 3 other horses, from which hemolysate was prepared and added to plasma at different concentrations. The within- and between-run coefficients of variation of all pools were <10%, and a good linearity was found. Three out of 4 hemolyzed serum samples had a decreased serum cTnT concentration. Plasma samples with a high hemolysis index showed a negative interference, resulting in a lower cTnT concentration. Results of the high-sensitivity cTnT assay were highly reproducible. Because samples from horses with musculoskeletal damage were included, further studies should test the possible cross-reactivity between troponin T of musculoskeletal and cardiac origin before the assay can be used in equine clinical practice.

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Prognostic Value of Combination of Cardiac Troponin T and B-Type Natriuretic Peptide after Initiation of Treatment in Patients with Chronic Heart Failure

Clinical Chemistry ◽

10.1373/clinchem.2003.021311 ◽

2003 ◽

Vol 49 (12) ◽

pp. 2020-2026 ◽

Cited By ~ 66

Author(s):

Junnichi Ishii ◽

Wei Cui ◽

Fumihiko Kitagawa ◽

Takahiro Kuno ◽

Yuu Nakamura ◽

...

Keyword(s):

Heart Failure ◽

Chronic Heart Failure ◽

Cardiac Troponin ◽

Troponin T ◽

Myocardial Damage ◽

Left Ventricular ◽

Functional Class ◽

Cardiac Troponin T ◽

Cardiac Events ◽

Nyha Functional Class

Abstract Background: Recent studies have suggested that cardiac troponin T (cTnT) and troponin I may detect ongoing myocardial damage involved in the progression of chronic heart failure (CHF). This study was prospectively designed to examine whether the combination of cTnT, a marker for ongoing myocardial damage, and B-type natriuretic peptide (BNP), a marker for left ventricular overload, would effectively stratify patients with CHF after initiation of treatment. Methods: We measured serum cTnT, plasma BNP, and left ventricular ejection fraction (LVEF) on admission for worsening CHF [New York Heart Association (NYHA) functional class III to IV] and 2 months after initiation of treatment to stabilize CHF (n = 100; mean age, 68 years). Results: Mean (SD) concentrations of cTnT [0.023 (0.066) vs 0.063 (0.20) μg/L] and BNP [249 (276) vs 753 (598) ng/L], percentage increased cTnT (>0.01 μg/L; 35% vs 60%), NYHA functional class [2.5 (0.6) vs 3.5 (5)], and LVEF [43 (13)% vs 36 (12)%] were significantly (P <0.01) improved 2 months after treatment compared with admission. During a mean follow-up of 391 days, there were 44 cardiac events, including 12 cardiac deaths and 32 readmissions for worsening CHF. On a stepwise Cox regression analysis, increased cTnT and BNP were independent predictors of cardiac events (P <0.001). cTnT >0.01 μg/L and/or BNP >160 ng/L 2 months after initiation of treatment were associated with increased cardiac mortality and morbidity rates. Conclusion: The combination of cTnT and BNP measurements after initiation of treatment may be highly effective for risk stratification in patients with CHF.

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Development of a Novel Sensor System Based on Magnetic Microspheres to Detect Cardiac Troponin T

International Journal of Polymer Science ◽

10.1155/2020/8855550 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Junrong Zhang ◽

Hongxiang Liu ◽

Baofeng Xu ◽

Sijun Huang ◽

Rui Liu ◽

...

Keyword(s):

Cardiac Troponin ◽

Troponin T ◽

Myocardial Damage ◽

Fluorescein Isothiocyanate ◽

High Specificity ◽

Magnetic Microspheres ◽

Cardiac Troponin T ◽

Serum Samples ◽

Magnetic Separator ◽

Specific Antibodies

Acute myocardial infarction (AMI) causes irreversible injury to cardiomyocytes in a short time and may result in various complications, severely threatening patient safety. Therefore, it is necessary to predict the possibility of AMI in the prophase. Prognostic detection of biomarkers that specifically reflect myocardial damage in a patient’s blood has become an essential mediating measure to prevent the serious occurrence of AMI. The present study is aimed at exploring a novel sensing system with high specificity and precision based on magnetic microspheres developed to detect cardiac troponin T (cTnT), which is the most specific diagnostic marker for AMI in cardiovascular diseases. Naive human cTnT protein in serum samples and antigens on functional magnetic microspheres will competitively bind with limited specific antibodies. After rapid removal of heterogeneous elements in the sera using a magnetic separator, fluorescein isothiocyanate-labeled immunoglobulin G is added to react with specific antibodies on the magnetic microspheres. Then, a flow cytometer is used to collect signals of different fluorescence intensities. The results show that the method is characterized by economy, high accuracy, and novelty. It can be used for the detection of cTnT in blood at 1.7–106.1 ng/mL, with a detection limit of 0.5 ng/mL. Thus, the proposed sensor improves the accuracy and efficiency of diagnosis before clinical deterioration of AMI.

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Effects of exercise on plasma myosin heavy chain fragments and MRI of skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.1992.72.2.656 ◽

1992 ◽

Vol 72 (2) ◽

pp. 656-663 ◽

Cited By ~ 69

Author(s):

J. Mair ◽

A. Koller ◽

E. Artner-Dworzak ◽

C. Haid ◽

K. Wicke ◽

...

Keyword(s):

Skeletal Muscle ◽

Cardiac Troponin ◽

Troponin T ◽

Plasma Concentrations ◽

Eccentric Contractions ◽

Cardiac Troponin T ◽

Skeletal Muscle Myosin ◽

Slow Skeletal Muscle ◽

Slow Twitch ◽

Muscle Myosin

The effects of a single series of high-force eccentric contractions involving the quadriceps muscle group (single leg) on plasma concentrations of muscle proteins were examined as a function of time, in the context of measurements of torque production and magnetic resonance imaging (MRI) of the involved muscle groups. Plasma concentrations of slow-twitch skeletal (cardiac beta-type) myosin heavy chain (MHC) fragments, myoglobin, creatine kinase (CK), and cardiac troponin T were measured in blood samples of six healthy male volunteers before and 2 h after 70 eccentric contractions of the quadriceps femoris muscle. Screenings were conducted 1, 2, 3, 6, 9, and 13 days later. To visualize muscle injury, MRI of the loaded and unloaded thighs was performed 3, 6, and 9 days after the eccentric exercise bout. Force generation of the knee extensors was monitored on a dynamometer (Cybex II+) parallel to blood sampling. Exercise resulted in a biphasic myoglobin release profile, delayed CK and MHC peaks. Increased MHC fragment concentrations of slow skeletal muscle myosin occurred in late samples of all participants, which indicated a degradation of slow skeletal muscle myosin. Because cardiac troponin T was within the normal range in all samples, which excluded a protein release from the heart (cardiac beta-type MHC), this finding provides evidence for an injury of slow-twitch skeletal muscle fibers in response to eccentric contractions. Muscle action revealed delayed reversible increases in MRI signal intensities on T2-weighted images of the loaded vastus intermedius and deep parts of the vastus lateralis. We attributed MRI signal changes due to edema in part to slow skeletal muscle fiber injury.(ABSTRACT TRUNCATED AT 250 WORDS)

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