scholarly journals Multicenter Clinical and Analytical Evaluation of the AxSYM Troponin-I Immunoassay to Assist in the Diagnosis of Myocardial Infarction

1999 ◽  
Vol 45 (2) ◽  
pp. 206-212 ◽  
Author(s):  
Fred S Apple ◽  
Andrew J Maturen ◽  
Richard E Mullins ◽  
Pennell C Painter ◽  
Melissa S Pessin-Minsley ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Muscle Injury ◽  
Troponin I ◽  
Dynamic Range ◽  
Chronic Renal Disease ◽  
Noncardiac Surgery ◽  
Minimum Detectable Concentration ◽  
Healthy Individuals ◽  
Detectable Concentration ◽  
Serial Samples

Abstract We evaluated the AxSYM troponin I (cTnI) immunoassay for assisting in the detection of acute myocardial infarction (AMI). At four sites, the total imprecision (CV) over 20 days was 6.3–10.2%. The minimum detectable concentration was 0.14 ± 0.05 μg/L. Comparison of cTnI measurements between the AxSYM and Stratus (n = 406) over the dynamic range of the AxSYM assay demonstrated good correlation, r = 0.881, with a proportional bias: AxSYM cTnI = 3.50(Stratus cTnI) − 1.10. The confidence intervals (95%) for the slope and intercept were 3.39–3.64 and −1.32 to −0.95, respectively. The expected cTnI concentration in healthy individuals was ≤0.5 μg/L, whereas the ROC curve-determined cutoff for AMI was 2.0 μg/L. This gave a diagnostic sensitivity of 91.8% and specificity of 92.4% when tested in serial samples collected within 24 h of admission in 633 patients presenting with chest pain, of which 122 had an AMI. The concordances of the AxSYM cTnI with the Stratus cTnI, OPUS cTnI, and Access cTnI were 95.3%, 95.1%, and 94.3%, respectively, from patients with suspected AMI. The AxSYM cTnI demonstrated excellent clinical specificity, ≥96%, in skeletal muscle injury, chronic renal disease, and same-day noncardiac surgery patients.

scholarly journals Troponin T and I Assays Show Decreased Concentrations in Heparin Plasma Compared with Serum: Lower Recoveries in Early than in Late Phases of Myocardial Injury

2000 ◽  
Vol 46 (6) ◽  
pp. 817-821 ◽  
Author(s):  
Willie Gerhardt ◽  
Gunnar Nordin ◽  
Ann-Katrin Herbert ◽  
Birgitta Linåker Burzell ◽  
Anders Isaksson ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Chest Pain ◽  
Cardiac Troponin ◽  
Myocardial Injury ◽  
Troponin I ◽  
Troponin T ◽  
Serum Samples ◽  
Heparin Plasma ◽  
Time Courses ◽  
Serial Samples

Abstract Background: Heparinized plasma samples allow more rapid analysis than serum samples, but preliminary studies showed lower cardiac troponin T (cTnT) results in plasma. We undertook a multicenter study to characterize this effect for cTnT and cardiac troponin I (cTnI). Methods: Blood samples were collected with and without heparin at five hospitals. cTnT was measured by a “third generation” assay (Elecsys®), and cTnI was measured by a commercial immunoassay (IMMULITE®). Results: Mean cTnT was 15% lower in heparin sampling tubes than in serum. Measured concentrations of cardiac troponins also decreased with increasing heparin concentrations added to sera. Heparin-induced losses were greater in early than in late phases after onset of chest pain. Addition of heparin (∼100 IU/mL) to serial samples from nine acute myocardial infarction patients produced mean cTnT losses of 33% at 1–12 h after onset of chest pain, 17% at 13–48 h, and 7% after 48 h. The changing heparin effects were seen for both cTnT and cTnI during time courses of individual patients with myocardial infarction. Conclusion: We suggest that binding of heparin to troponins decreases immunoreactivity, especially in early phases of myocardial injury. The resulting losses may depend on the antibodies used in each troponin assay.

scholarly journals Development of sensitive immunoassays to detect amylin and amylin-like peptides in unextracted plasma

1996 ◽  
Vol 42 (4) ◽  
pp. 576-585 ◽  
Author(s):  
A J Percy ◽  
D A Trainor ◽  
J Rittenhouse ◽  
J Phelps ◽  
J E Koda
Keyword(s):  
Pancreatic Beta Cells ◽  
Dynamic Range ◽  
Carboxyl Terminus ◽  
Minimum Detectable Concentration ◽  
Sensitive Assay ◽  
Fluorescent Substrate ◽  
Detectable Concentration ◽  
Sandwich Type ◽  
Human Amylin ◽  
Enzyme Alkaline Phosphatase

Abstract Amylin is a 37-amino-acid polypeptide synthesized in and secreted from pancreatic beta cells along with insulin. Its biological actions include the slowing and reduction of postmeal increases in plasma glucose concentrations. Studies of the basic amylin biology in humans have been hampered by the lack of a rapid, sensitive assay capable of measuring physiological concentrations of amylin in small volumes of plasma. We report here two sandwich-type immunoassays that use pairs of monoclonal antibodies, the fluorescent substrate 4-methylumbelliferyl phosphate, and the enzyme alkaline phosphatase. The minimum detectable concentration of amylin in 50 microL of plasma was 0.5 to 2 pmol/L, and the dynamic range was 2 to 100 pmol/L. The assays had average intraassay CVs of <10%, average interassay CVs of <15%, and good linearity on dilution and recovery of added amylin. The two assays use the same detection antibody, which binds to the carboxyl terminus of the molecule, but different capture antibodies. One of the assays measures only human amylin; the other also detects amylin-like peptides. Examples of measurements in human plasma are provided in subjects with impaired glucose tolerance and in nondiabetic controls.

scholarly journals Oxidative stress in myocardial infarction-does it correlate with the cardiac marker troponin?

2021 ◽  
Vol 8 (3) ◽  
pp. 190-192
Author(s):  
Pallavi R ◽  
Prabha S P ◽  
Sumina Cherian ◽  
Venugopal K ◽  
Geetha A
Keyword(s):  
Oxidative Stress ◽  
Myocardial Infarction ◽  
Heart Attack ◽  
Significant Positive Correlation ◽  
Troponin I ◽  
Healthy Controls ◽  
Healthy Individuals ◽  
Cardiac Marker ◽  
Positive Correlation ◽  
Significant Difference

A myocardial infarction (MI), often known as a heart attack, occurs when blood supply to a region of the heart is reduced or stopped, resulting in heart muscle damage. One of the elemental mechanisms responsible for the development of myocardial infarction is oxidative stress. The study aims to assess the Oxidative stress and Troponin I levels in patients with myocardial infarction (MI) and compare them with the level of these parameters in healthy controls. An attempt has been made to find if there is any correlation between oxidative stress and Troponin I levels in patients with myocardial infarction.The Cardiac marker Troponin I and the marker of oxidative stress malondialdehyde were estimated in 30 patients with myocardial infarction and 30 healthy individuals who acted as controls. A statistically significant difference was observed between Troponin I and MDA in patients with MI as compared with controls. A significant positive correlation was also observed between MDA and Troponin I levels. In our study there wasa significant positive correlation between oxidative stress and Troponin I. Further studies with a larger number of subjects will be needed to find if oxidative stress plays a role in the pathogenesis of myocardial infarction.

scholarly journals Full-Size Cardiac Troponin I and Its Proteolytic Fragments in Blood of Patients with Acute Myocardial Infarction: Antibody Selection for Assay Development

2018 ◽  
Vol 64 (7) ◽  
pp. 1104-1112 ◽  
Author(s):  
Ivan A Katrukha ◽  
Alexander E Kogan ◽  
Alexandra V Vylegzhanina ◽  
Alexey V Kharitonov ◽  
Natalia N Tamm ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Cardiac Troponin I ◽  
Amino Acid Residues ◽  
Serum Samples ◽  
Before And After ◽  
Stable Part ◽  
Serial Samples

Abstract BACKGROUND In the blood of patients with acute myocardial infarction (AMI), cardiac troponin I (cTnI) presents as an intact molecule with a repertoire of proteolytic fragments. The degradation of cTnI might negatively influence its precise immunodetection. In this study we identified cTnI fragments and calculated their ratio in the blood of patients at different times after AMI to discriminate the most stable part(s) of cTnI. METHODS Serial serum samples were collected from AMI patients within 1 to 36 h after the onset of chest pain both before and after stenting. cTnI and its fragments were immunoextracted from serum samples and analyzed by Western blotting with monoclonal antibodies (mAbs) specific to the different epitopes of cTnI and by 2 in-house immunoassays specific to the central and terminal portions of cTnI. RESULTS Intact cTnI and its 11 major fragments were detected in blood of AMI patients. The ratio of the fragments in serial samples did not show large changes in the period 1–36 h after AMI. mAbs specific to the epitopes located approximately between amino acid residues (aar) 34 and 126 stained all extracted cTnI. mAbs specific to aar 23–36 and 126–196 recognized approximately 80% to 90% (by abundance) of cTnI. CONCLUSIONS In addition to mAbs specific to the central part of cTnI (approximately aar 34–126), antibodies specific to the adjacent epitopes (approximately aar 23–36 and 126–196) could be used in assays because they recognize ≥80% of cTnI in patients' blood samples within the first 36 h after AMI.

scholarly journals Fluoroenzymometric method to measure cardiac troponin I in sera of patients with myocardial infarction

1996 ◽  
Vol 42 (9) ◽  
pp. 1460-1466 ◽  
Author(s):  
M Zaninotto ◽  
S Altinier ◽  
M Lachin ◽  
P Carraro ◽  
M Plebani
Keyword(s):  
Myocardial Infarction ◽  
Chest Pain ◽  
Operating Characteristic ◽  
Troponin I ◽  
Chronic Renal Disease ◽  
Characteristic Curve ◽  
Interquartile Range ◽  
Renal Diseases ◽  
Muscle Injuries ◽  
Healthy Donors

Abstract The aim of our study was to evaluate the clinical relevance of serum troponin I (TnI) as a marker of ischemic myocardial injury by using an automated fluoroenzymometric assay. The reference range for serum TnI was established by measuring serum TnI concentrations in blood from 75 healthy donors. The concentration was then compared with serum creatine kinase (CK) activity, CK-MB mass, and myoglobin concentrations in 20 patients with myocardial infarction diagnosed according to the WHO criteria, 20 patients with chest pain of nonischemic origin, 9 patients with unstable angina, 11 with stable angina, 11 patients with chronic muscular diseases, 6 patients with muscular trauma without chest contusion, and 13 patients with chronic renal disease. We found that: (a) 99% of the blood donors had TnI concentrations <0.26 microgram/L (detection limit of the assay in our study); (b) TnI values in acute myocardial infarction (AMI) patients 4 h after onset of chest pain showed a sensitivity of 0.769 and a specificity of 1.0 at a decisional concentration for AMI of 1 microgram/L, even in the presence of severe skeletal muscle injuries or renal diseases; (c) the increase in TnI concentrations after infarction (interquartile range 3.25-6 h) and the peak occurred later (interquartile range 11.5-24 h) than the rise found in myoglobin and CK-MB, but the increase persisted much longer (>96 h); (d) receiver-operating characteristic curve analysis showed the high diagnostic accuracy of TnI in diagnosing AMI even in patients in whom traditional biochemical markers are adversely influenced by underlying clinical situations.

Diagnostic and Prognostic Value of Cardiac Troponin I Assays in Patients Admitted With Symptoms Suggestive of Acute Coronary Syndrome

2004 ◽  
Vol 128 (4) ◽  
pp. 430-434
Author(s):  
Fred S. Apple ◽  
Heidi E. Quist ◽  
Mary Ann M. Murakami
Keyword(s):  
Myocardial Infarction ◽  
Acute Coronary Syndrome ◽  
Risk Stratification ◽  
Coefficient Of Variation ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Dynamic Range ◽  
Cardiac Troponin I ◽  
Rank Test ◽  
Coronary Syndrome

Abstract Context.—Increasing numbers of patients are presenting to emergency departments with symptoms suggestive of an acute myocardial infarction. Objective.—To demonstrate the comparative performance of the Ortho Vitros Troponin I and Beckman Access AccuTnI assays used to detect myocardial infarction and to develop risk stratification schemes for all-cause death in patients who presented with myocardial ischemia symptoms that were suggestive of acute coronary syndrome (ACS). Design.—The prospective enrollment of patients with ACS and the measurement of serial plasma samples by 2 commercial cardiac troponin I (cTnI) assays. Setting.—A metropolitan medical center that admitted patients with ACS during a 2-month period. Patients.—The study population consisted of 200 consecutively admitted patients who presented with symptoms that were suggestive of ACS. Results.—Correlation scatterplots showed no significant bias between cTnI assays based on 659 specimens across the dynamic range of each assay. Only minor differences in slopes and intercepts were observed between assays when correlations were based across selected concentration ranges. The receiver operating characteristic curve areas for the detection of myocardial infarction were not significantly different (Ortho, .991; Beckman, .995). At the 99th percentile (Beckman, 0.04 μg/L; Ortho, 0.08 μg/L), each assay demonstrated 100% sensitivity with 78% and 80% specificity, respectively. Kaplan-Meier survival curves and the log-rank test were used to compare time-to-event data. Patients with increased baseline cTnI values had higher odds ratios of death than did those with normal concentrations. For Ortho, the 99th percentile cutoff was 5.9, and the 10% coefficient of variation cutoff was 10.3; for Beckman, the 99th percentile cutoff was 31.4, and the 10% coefficient of variation cutoff was 15.3. Conclusions.—Comparable diagnostic and risk stratification abilities were demonstrated in patients with ACS by the Ortho Vitros and Beckman Access cTnI assays, with no significant analytic bias between cTnI assays.

scholarly journals Cardiac troponin I measurement with the ACCESS® immunoassay system: analytical and clinical performance characteristics

1998 ◽  
Vol 44 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Robert H Christenson ◽  
Fred S Apple ◽  
David L Morgan ◽  
Gladys L Alonsozana ◽  
Kristin Mascotti ◽  
...  
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Clinical Performance ◽  
Characteristic Curve ◽  
Receiver Operator Characteristic Curve ◽  
Cardiac Troponin I ◽  
Minimum Detectable Concentration ◽  
Cardiac Symptoms ◽  
Limit Of Quantitation ◽  
Detectable Concentration

Abstract We evaluated the ACCESS® cardiac troponin I (cTnI) immunoassay as a marker for myocardial infarction (MI). Total imprecision was 6.0% to 13.5%, the minimum detectable concentration was 0.007 μg/L, and the limit of quantitation was 0.046 μg/L. Comparison of cTnI measurement between the ACCESS and Stratus systems (n = 114) showed a proportional difference: ACCESS cTnI = 0.0996 Stratus cTnI + 0.049 μg/L (r = 0.811). Fifty-nine of 61 ambulatory patients without cardiac symptoms had no detectable cTnI (95% range, 0.00 to 0.025 μg/L). The optimum cutoff for discriminating MI (n = 289, 45 with MI) was 0.15 μg/L by receiver operator characteristic curve analysis; at this cutoff, the ACCESS cTnI assay showed a sensitivity of 88.9% (95% CI, 79.7–98.1%) and specificity of 91.8% (95% CI, 88.4–95.2%). The ACCESS cTnI assay results showed 89.4% and 93.0% concordance with the MB isoenzyme of creatine kinase (CK-MB) mass and Stratus cTnI results, respectively, for classification of patients with suspected MI. The ACCESS cTnI assay appears to show sensitivity and specificity comparable with those of both CK-MB mass and Stratus cTnI assays for the diagnosis of MI in patients presenting within 12 h of onset of symptoms.

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