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Background: We have found previously that in acute myocardial infarction (AMI), cardiac troponin T (cTnT) is degraded in a time-dependent pattern. We investigated whether cTnT forms differed in patients with chronic cTnT increases, as seen with renal dysfunction, from those in the acute phase of myocardial infarction., Methods: We separated cTnT forms by gel filtration chromatography (GFC) in end-stage renal disease (ESRD) patients: prehemodialysis (pre-HD) and post-HD (n = 10) and 2 months follow-up (n = 6). Purified (cTnT) standards, quality control materials of the clinical cTnT immunoassay (Roche), and AMI patients' sera also were analyzed. Immunoprecipitation and Western blotting were performed with the original cTnT antibodies from the clinical assay and antibodies against the N- and C-terminal end of cTnT., Results: GFC analysis revealed the retention of purified cTnT at 27.5 mL, identical to that for cTnT in quality controls. For all ESRD patients, one cTnT peak was found at 45 mL, pre- and post-HD, and stable over time. Western blotting illustrated that this peak corresponded to cTnT fragments <18 kDa missing the N- and C-terminal ends. AMI patients' sera revealed cTnT peaks at 27.5 and 45 mL, respectively, corresponding to N-terminal truncated cTnT of 29 kDa and N- and C-terminal truncated fragments of <18 kDa, respectively., Conclusions: We found that cTnT forms in ESRD patients are small (<18 kDa) and different from forms seen in AMI patients. These insights may prove useful for development of a more specific cTnT immunoassay, especially for the acute and diagnostic phase of myocardial infarction., (© 2016 American Association for Clinical Chemistry.)

Prolonged endurance-type exercise is associated with elevated cardiac troponin (cTn) levels in asymptomatic recreational athletes. It is unclear whether exercise-induced cTn release mirrors a physiological or pathological underlying process. The aim of this study was to provide a direct comparison of the release kinetics of high-sensitivity cTnI (hs-cTnI) and T (hs-cTnT) after endurance-type exercise. In addition, the effect of remote ischemic preconditioning (RIPC), a cardioprotective strategy that limits ischemia-reperfusion injury, was investigated in a randomized controlled crossover manner. Twenty-five healthy volunteers completed an outdoor 30-km running trial preceded by RIPC (4 × 5 min 220 mm Hg unilateral occlusion) or control intervention. hs-cTnT, hs-cTnI, and sensitive cTnI (s-cTnI) concentrations were examined before, immediately after, 2 and 5 hours after the trial. The completion of a 30-km run resulted in a significant increase in circulating cTn (time: all p <0.001), with maximum hs-cTnT, hs-cTnI, and s-cTnI levels of 47 ± 27, 69 ± 62, and 82 ± 64 ng/L (mean ± SD), respectively. Maximum hs-cTnT concentrations were measured in 60% of the participants at 2 hours after exercise, compared with maximum hs-cTnI and s-cTnI concentrations at 5 hours in 84% and 80% of the participants. Application of an RIPC stimulus did not reduce exercise-induced cTn release (time × trial: all p >0.5). In conclusion, in contrast to acute myocardial infarction, maximum hs-cTnT levels after exercise precede maximum hs-cTnI levels. Distinct release kinetics of hs-cTnT and hs-cTnI and the absence of an effect of RIPC favors the concept that exercise-induced cTn release may be mechanistically distinct from cTn release in acute myocardial infarction., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Unstable plaque characteristics on coronary CT angiography (CTA), serum high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) concentrations are associated with cardiovascular events., Objective: To investigate the association between coronary CTA defined quantifiable plaque characteristics, hs-cTnT and NT-proBNP., Methods: 81 consecutive stable chest pain patients with an intermediate-to-high risk were analyzed. Coronary CTA was performed using a 64-slice multidetector-row CT-scanner. Total coronary plaque volume, calcified volume, non-calcified volume, plaque burden, remodeling index (RI) and number of plaques were measured using dedicated software. A total plaque score ("Sum plaque score") incorporating total plaque volume, RI, plaque burden and number of plaques was defined. Hs-cTnT and NT-proBNP concentrations were measured in serum samples before coronary CTA., Results: Univariate regression analysis demonstrated significant associations of hs-cTnT and NT-proBNP with total plaque volume (r hs-cTnT = .256; r NT-proBNP = .270), calcified volume (r hs-cTnT = .344; r NT-proBNP = .344), RI (r hs-cTnT = .335; r NT-proBNP = .342) and number of plaques (r hs-cTnT = .355; r NT-proBNP = .301) (all P values ≤ .021). Non-calcified plaque volume showed no association with hs-cTnT and NT-proBNP (r hs-cTnT = .050; r NT-proBNP = .087; P value = .660 and P value = .442). The "Sum plaque score" showed the highest correlation compared to other plaque parameters (r hs-cTnT = .362; r NT-proBNP = .409; P value = .001 and P value ≤ .001)., Conclusion: Our data suggest that coronary plaque morphology parameters, derived by dedicated software, are associated with serum hs-cTnT and NT-proBNP concentrations., (Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Objective: Cardiac troponins T (cTnT) and I (cTnI) are the preferred biomarkers to detect myocardial damage. The present study explores the value of measuring cardiac troponins (cTn) in nursing home residents, by investigating its relation to heart failure and 1-year mortality using 1 cTnT and 2 cTnI assays that are widely used in clinical practice., Design: All participants underwent extensive clinical examinations and echocardiographic assessment for the diagnosis of heart failure. cTn was measured using high-sensitive (hs)- cTnT (Roche), hs-cTnI (Abbott), and sensitive cTnI (Beckman) assays. The glomerular filtration rate was estimated (eGFR) using serum creatinine and cystatin C concentrations. Data on all-cause mortality were collected at 1-year follow-up., Participants and Setting: Participants were 495 long-term nursing home residents, older than 65 years, of 5 Dutch nursing home organizations., Results: Median (IQR) concentrations were 20.6 (17.8-30.6), 6.8 (4.1-12.5), and 4.0 (2.0-8.0) ng/L for hs-cTnT, hs-cTnI, and cTnI, respectively. In total, 79% had elevated hs-cTnT concentrations, whereas only 9% and 5% of hs-cTnI and cTnI concentrations were elevated. Most important and independent determinants for higher hs-cTnT and hs-cTnI concentrations were heart failure and renal dysfunction. Whereas both heart failure (odds ratio [OR] 3.4) and eGFR lower than 60 mL/min/1.73 m(2) (OR 3.6) were equal contributors to higher hs-cTnT concentrations (all P < .001), hs-cTnI and cTnI were less associated with renal dysfunction (OR of, respectively, 1.9 and 2.1; P < .01) in comparison with heart failure (OR 4.3 and 4.7, respectively, P < .001). Furthermore, residents with higher hs-cTnT or hs-cTnI concentrations (fourth quartile) had respectively 4 versus 2 times more risk of 1-year mortality compared with lower concentrations., Conclusion: Regardless of their cardiac health, hs-cTnT but not hs-cTnI concentrations were elevated in almost all aged nursing home residents, questioning the use of the current diagnostic cutoff in elderly with high comorbidity. Nonetheless, measuring cardiac troponins, especially hs-cTnT, had a promising role in assessing future risk of mortality., (Copyright © 2015 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.)

Aim: Cardiac troponin I (cTnI) and T (cTnT) are the most important biomarkers in the diagnosis of acute myocardial infarction (AMI). Nevertheless, they can be elevated in the absence of AMI. It is unclear if such elevations represent irreversible cardiomyocyte-damage or leakage from viable cardiomyocytes. Our objective is to evaluate whether cTn is released from viable cardiomyocytes in response to ischemia and to identify differences in the release of cTn and its molecular forms., Methods and Results: HL-1 cardiomyocytes (mouse) were subjected to ischemia (modeled by anoxia with glucose deprivation). The total contents and molecular forms of cTn were determined in culture media and cell lysates. Cell viability was assessed from the release of lactate dehydrogenase (LDH). Before the release of LDH, the intracellular cTn content in ischemic cells decreased significantly compared to control (52% for cTnI; 23% for cTnT) and was not matched by a cTn increase in the medium. cTnI decreased more rapidly than cTnT, resulting in an intracellular cTnT/cTnI ratio of 25.5 after 24 h of ischemia. Western blots revealed changes in the relative amounts of fragmented cTnI and cTnT in ischemic cells., Conclusions: HL-1 cardiomyocytes subjected to simulated ischemia released cTnI and cTnT only in combination with the release of LDH. We find no evidence of cTn release from viable cardiomyocytes, but did observe a significant decrease in cTn content, before the onset of cell death. Intracellular decrease of cTn in viable cardiomyocytes can have important consequences for the interpretation of cTn values in clinical practice., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: Cardiac troponin T (cTnT) is widely used for the diagnosis of acute myocardial infarction (AMI). However, it is still unclear whether degraded cTnT forms circulate in the patient's blood. We therefore aimed to elucidate which cTnT forms are detected by the clinical assay., Methods: Separation of cTnT forms by gel filtration chromatography (GFC) was performed in sera from 13 AMI patients to examine cTnT degradation. The GFC eluates were subjected to Western blot analysis with the original antibodies from the Roche immunoassay used to mimic the clinical cTnT assay. To investigate the degradation pattern with time, standardized serum samples of 18 AMI patients collected 0-72 h after admission were analyzed by Western blot analysis., Results: GFC analysis of AMI patients' sera revealed 2 cTnT peaks with retention volumes of 5 and 21 mL. Western blot analysis identified these peaks as cTnT fragments of 29 and 14-18 kDa, respectively. Furthermore, the performance of direct Western blots on standardized serum samples demonstrated a time-dependent degradation pattern of cTnT, with fragments ranging between 14 and 40 kDa. Intact cTnT (40 kDa) was present in only 3 patients within the first 8 h after hospital admission., Conclusions: These results demonstrate that the Roche cTnT immunoassay detects intact as well as degraded cTnT forms in AMI patients' sera during the period of diagnostic testing. Moreover, following AMI, cTnT is degraded in a time-dependent pattern.