Protein kinase A (PKA) phosphorylation of myofibril proteins constitutes an important pathway for β-adrenergic modulation of cardiac contractility and relaxation. PKA targets the N-terminus (Ser-23/24) of cardiac troponin I (cTnI), cardiac myosin-binding protein C (cMyBP-C) and titin. The effect of PKA-mediated phosphorylation on the magnitude of contraction has been studied in some detail, but...

BACKGROUND Previous studies have shown superior clinical performance of the cardiac troponin I (cTnI) assay from Beckman-Coulter Diagnostics. This assay had a unique combination of monoclonal antibodies with 2 monoclonal antibodies directed against epitopes near the NH(2) terminus of the heart-specific region of troponin I. The approach has been adopted by the new cTnI assay from Abbott Diagnos...

BACKGROUND Myocardial infarction is characterized by an increase of cardiac troponin I (cTnI) above the 99th percentile of a reference population. Our hospital switched from 1 contemporary cTnI assay to another and observed a doubling of cTnI results above the assays' respective 99th percentile cutoffs. We investigated the potential impact on inpatient management and outcomes. METHODS We perf...

The phosphorylation of cardiac troponin I (cTnI) plays an important role in the contractile dysfunction associated with heart failure. Human cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific functional kinase that can bind to cTnI in a yeast two-hybrid screen. The purpose of this study was to investigate whether TNNI3K can phosphorylate cTnI at specific sites and to exa...

Cardiac troponin I (cTnI) plays a critical role in regulation of cardiac function. Studies have shown that the deficiency of cTnI or mutations in cTnI (particularly in the C-terminus of cTnI) results in diastolic dysfunction (impaired relaxation) due to an increased myofibril sensitivity to calcium. The first clinical study revealing the association between restrictive cardiomyopathy (RCM) with...

BACKGROUND Elevated serum cardiac troponin T (cTnT) levels are frequently observed in chronic dialysis patients and have been shown to be associated with increased morbidity and mortality. The aim of this study was to determine whether cardiac troponin I (cTnI), which is less frequently elevated, has similar clinical significance. METHODS We studied 101 asymptomatic patients with no clinical ...

14.5 mg/L; range, 6.9 –24.8 mg/L). No correlation was found between cTnI and ST-segment changes. Electrocardiograms showed ST-segment alteration in two patients with echocardiographic signs of MC and in two patients without MC signs. cTnI concentrations peaked between 6 and 12 h after chest trauma and disappeared 48–96 h after the trauma. Thus, the diagnostic window was narrower than it is duri...

In addition to the core structure conserved in all troponin I isoforms, cardiac troponin I (cTnI) has an ∼30 amino acids NH(2)-terminal extension. This peptide segment is a heart-specific regulatory structure containing two Ser residues that are substrates of PKA. Under β-adrenergic regulation, phosphorylation of cTnI in the NH(2)-terminal extension increases the rate of myocardial relaxation. ...

To improve the specificity of biochemical markers of myocardial infarction (MI), we have developed a double monoclonal "sandwich" enzyme immunoassay to measure cardiac troponin-I (cTnI) in serum. We produced eight IgG monoclonal antibodies against human cardiac troponin-I (cTnI) and tested them against human and animal (canine, bovine, and rabbit) troponins. Five antibodies were cardiac-specifi...

Circulating cardiac troponins are markers of myocardial injury. We sought to determine whether cardiac troponin I (cTnI), measured by a sensitive assay, is associated with disease severity and prognosis in pulmonary arterial hypertension (PAH). cTnI was measured in 68 patients with PAH diagnostic category 1 in a research-based sensitive immunoanalyser with a lower limit of detection of 0.008 ng...