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...

Muscle contraction is regulated by troponin-tropomyosin, which blocks and unblocks myosin binding sites on actin. To elucidate this regulatory mechanism, the three-dimensional organization of troponin and tropomyosin on the thin filament must be determined. Although tropomyosin is well defined in electron microscopy helical reconstructions of thin filaments, troponin density is mostly lost. Her...

Localization and quantification studies were carried out on bay-scallop (Aequipecten irradians) striated-muscle troponin Cand troponin I-like proteins. Indirect immunofluorescence microscopy of scallop myofibrils stained with either rabbit anti-(scallop troponin I) or anti-(scallop troponin C) antibodies shows staining of all I-bands observed. The results of quantification studies using sodium ...

Striated muscle thin filaments contain many troponin molecules, which contact each other indirectly via tropomyosin and actin. Such allosteric interactions between troponin molecules may be responsible for cooperative Ca2+ binding to the regulatory sites of the cardiac thin filament (Tobacman, L. S., and Sawyer, D. S. (1990) J. Biol. Chem. 265, 931-939). To test whether thin filament-bound trop...

We have investigated the structure of the cTnC-cTnI-cTnT(198-298) calcium-saturated, ternary cardiac troponin complex by small-angle scattering with contrast variation. Shape restoration was also applied to the scattering information resulting from the deuterated cTnC subunit, the unlabeled cTnI-cTnT(198-298) subunits, and the entire complex. The experimental results and modeling indicate that ...

We describe an improved procedure using a standard microplate immunoassay reader to measure the concentration of troponin T in human serum. We also describe an immunoassay for troponin I in serum. Only 160 microliters of serum are needed for a single analysis of each troponin. For comparison, creatine kinase MB mass analysis in serum was performed with a commercial luminometric method. From 95 ...

Myocardial ischemia is characterized by reduced blood flow to cardiomyocytes, which can lead to acidosis. Acidosis decreases the calcium sensitivity and contractile efficiency of cardiac muscle. By contrast, skeletal and neonatal muscles are much less sensitive to changes in pH. The pH sensitivity of cardiac muscle can be reduced by replacing cardiac troponin I with its skeletal or neonatal cou...

The myoepithelial sheath of the Caenorhabditis elegans somatic gonad has non-striated actomyosin networks that provide contractile forces during ovulation, a process in which a mature oocyte is expelled from the ovary. Troponin T and troponin C are known regulators of contraction of the myoepithelial sheath. These are two of the three components of the troponin complex that is generally conside...

OBJECTIVES We sought to assess the mechanism and prognostic value of elevated troponins in patients without acute coronary syndromes (ACS). BACKGROUND Cardiac troponins are used as specific markers for the diagnosis of ACS. Recent studies reported a considerable number of critically ill patients without ACS as being troponin-positive, especially patients with sepsis, pulmonary embolism, renal...

prolonged or repeated exposure to cement dust, depending on the duration, level of exposure and individual sensitivity has health implications on the skin, eyes, respiratory and haematological systems. this study assessed cardiovascular disease risk factors and cardiac markers among cement workers of nigerian origin to determine the effects of duration of exposure to cement dust on these parame...