The sarcomere is the basic unit of myocardial contraction. Each sarcomere is composed of two longitudinal muscle groups: thick filaments and thin filaments. The thick filaments, which are located in the middle of the sarcomeres, 1.5-1.6 mm in length and 10 nm in diameter, are composed of myosin molecules. Myosin (with a molecular weight of 500000 kDa) is a complex, asymmetrical molecule, with a...

Recent reports have demonstrated the presence of two isoforms of troponin I in the human fetal heart, namely, cardiac troponin I and slow skeletal muscle troponin I. Structural and physiological considerations indicate that these isoforms would confer differing contractile properties on the myocardium, particularly on the phosphorylation-mediated regulation of contractility by adrenergic agonis...

To improve the specificity of biochemical markers of myocardial infarction (MI) a method to measure cardiac troponin-I (CTn-I) was developed. CTn-I is a protein unique to cardiac muscle and is released after MI. Consecutive 150 patients admitted to the coronary care unit was studied. Value of CTn-I was determined in all samples. CTn-I concentration in the MI patients group was increased com...

The rapid and reliable diagnosis of acute myocardial infarction is a major unmet clinical need. We conducted a multicenter study to examine the diagnostic accuracy of new, sensitive cardiac troponin assays performed on blood samples obtained in the emergency department from 718 consecutive patients who presented with symptoms suggestive of acute myocardial infarction. Cardiac troponin concentra...

The troponin complex, composed of Troponin-I, Troponin-T and Troponin-C, is an essential mediator of the contraction of striated muscle downstream of calcium signaling in almost all bilaterians. However, in echinoderms and hemichordates, collectively termed Ambulacraria, the components of the troponin complex have never been isolated, thus suggesting that these organisms lost the troponin syste...

1. Troponin I prepared from rabbit hearts contains 1.0-1.5 mol of P/mol when isolated by affinity chromatography. Most of the covalently bound phosphate is located in residues 1-48 of the molecule. 2. 3':5'-Cyclic AMP-dependent protein kinase catalyses phosphorylation at serine-20 and serine-146. Serine-20 is more rapidly phosphorylated than serine-146. 3. In troponin I prepared from frozen hea...

The effect troponin I phosphorylation has on the Ca2+-binding properties of troponin C (TnC) in the whole troponin complex reconstituted from cardiac troponin I (TnI), troponin T, and TnC has been measured. To selectively follow Ca2+ binding at the Ca2+-specific sites of TnC, this subunit was labeled with the fluorescent probe 2-(4’-iodo-acetamidoanilino)naphthalene-6sulfonic acid before recons...

We have analyzed by different immunological methods the proteolytic degradation of cardiac troponin I (cTnI) in human necrotic tissue and in serum. cTnI is susceptible to proteolysis, and its degradation leads to the appearance of a wide diversity of proteolytic peptides with different stabilities. N- and C-terminal regions were rapidly cleaved by proteases, whereas the fragment located between...

foot and mouth disease (fmd) is a highly contagious viral disease of cloven-hooved livestock and wildlife results to relatively high mortality in young animals. despite the numerous reports of fmd-related death in neonates, there is little data available on various aspects of fmd in lambs. this report describes myocarditis associated with fmd in five, one week to three months old lambs. the lam...

INTRODUCTION The aim of this study was to identify clinical variables which may be independently associated with positivity of a cardiac troponin I (cTnI) assay in a large population of patients admitted to the emergency department (ED). MATERIALS AND METHODS 3166 subjects, with at least two troponin I tests ordered within 6 hours in the ED, were studied. Patient data were statistically analy...