BACKGROUND Cardiac troponin I and T (cTnI and cTnT) are specific biochemical serum markers for acute myocardial infarction (AMI). However, cTnI diagnostic assays are plagued by difficulties, resulting in >/=20-fold differences in measured values. These discrepancies may result from the release of the numerous cTnI modification products that are present in ischemic myocardium. The resolution of ...

OBJECTIVES ST-elevation and non-ST-elevation myocardial infarction (STEMI, NSTEMI) are considered two distinct pathophysiologic entities. We evaluated cardiac troponin I (cTnI) release in STEMI and NSTEMI using a "contemporary" (CV>10 to 20% at the 99th percentile concentration) cTnI assay for patients undergoing early percutaneous coronary intervention (PCI). DESIGN AND METHODS 856 patients ...

The cardiac myofilament protein troponin I (cTnI) is phosphorylated by protein kinase C (PKC), a family of serine/threonine kinases activated within heart muscle by a variety of agonists. cTnI is also a substrate for cAMP-dependent protein kinase (PKA) activated during beta-adrenergic signaling. To investigate the role of cTnI phosphorylation in contractile regulation by these pathways, we gene...

Cardiac troponin (cTn) is a key molecule in the regulation of human cardiac muscle contraction. The N-terminal cardiac-specific peptide of the inhibitory subunit of troponin, cTnI (cTnI(1-39)), is a target for phosphorylation by protein kinase A (PKA) during β-adrenergic stimulation. We recently presented evidence indicating that this peptide interacts with the inhibitory peptide (cTnl(137-147)...

BACKGROUND As a part of an International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) project to prepare a commutable reference material for cardiac troponin I (cTnI), a pilot study evaluated current cTnI assays for measurement equivalence and their standardization capability. METHODS cTnI-positive samples collected from 90 patients with suspected acute myocardial infarctio...

Elucidating the relative roles of cardiac troponin I (cTnI) and phospholamban (PLN) in beta-adrenergic-mediated hastening of cardiac relaxation has been challenging and controversial. To test the hypothesis that beta-adrenergic phosphorylation of cTnI has a prominent role in accelerating cardiac myocyte relaxation performance we used transgenic (Tg) mice bearing near complete replacement of nat...

Troponin, a contractile protein of the thin filament of striated muscle, consists of three subunits: troponin C (TnC), troponin T (TnT), and troponin I (TnI). Cardiac troponin I (cTnI) plays a critical role in regulation of cardiac function. The physiological effect of cTnI, as an inhibitory subunit of troponin complex, is to prevent the interaction between myosin heavy chain heads and actins, ...

BACKGROUND Cardiac troponin I (cTnI) is a sensitive marker of cardiac injury, but cTnI assays, like other immunoassays, are susceptible to interferences. We evaluated the presence of interfering substances by measuring the recovery of cTnI added to samples from volunteers and from patients with acute coronary syndromes (ACS). METHODS We added a ternary complex of human cardiac troponin (30-50...

The interaction of Cardiac Troponin C (cTnC) and Cardiac Troponin I (cTnI) plays a critical role in transmitting the Ca (2+) signal to the other myofilament proteins in the activation of cardiac muscle contraction. As such, the cTnC-cTnI interface is a logical target for cardiotonic agents such as levosimendan that can modulate the Ca (2+) sensitivity of the myofilaments. Evidence indicates tha...