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Celivarone
Celivarone is an experimental drug being tested for use in pharmacological antiarrhythmic therapy. Cardiac arrhythmia is any abnormality in the electrical activity of the heart. Arrhythmias range from mild to severe, sometimes causing symptoms like palpitations, dizziness, fainting, and even death. They can manifest as slow (bradycardia) or fast (tachycardia) heart rate, and may have a regular or irregular rhythm. Molecular causes of cardiac arrhythmias The causes of cardiac arrhythmias are numerous, from structural changes in the conduction system (the sinoatrial and atrioventricular nodes, or His-Purkinje system) and cardiac muscle, to mutations in genes coding for ion channels of the heart. Movement of ions, particularly Na+, Ca2+ and K+, causes depolarizations of cell membranes in node cells, which are then transmitted to cardiac muscle cells to induce contraction. After depolarization, the ions are moved back to their original locations, leading to repolarization of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Experimental Drug
An experimental drug is a medicinal product (a drug or vaccine) that has not yet received approval from governmental regulatory authorities for routine use in human or veterinary medicine. A medicinal product may be approved for use in one disease or condition but still be considered experimental for other diseases or conditions. In 2018 the United States of America signed the legislation "Right to Try", this allows individuals who fit into the criteria to try experimental drugs that are not yet deemed safe. In the United States, the body responsible for approval is the U.S. Food and Drug Administration (FDA), which must grant the substance Investigational New Drug (IND) status before it can be tested in human clinical trials. IND status requires the drug's sponsor to submit an IND application that includes data from laboratory and animal testing for safety and efficacy. A drug that is made from a living organism or its products undergoes the same approval process but is called a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin ''calx'' "lime", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventricular Fibrillation
Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the ventricles of the heart quiver. It is due to disorganized electrical activity. Ventricular fibrillation results in cardiac arrest with loss of consciousness and no pulse. This is followed by sudden cardiac death in the absence of treatment. Ventricular fibrillation is initially found in about 10% of people with cardiac arrest. Ventricular fibrillation can occur due to coronary heart disease, valvular heart disease, cardiomyopathy, Brugada syndrome, long QT syndrome, electric shock, or intracranial hemorrhage. Diagnosis is by an electrocardiogram (ECG) showing irregular unformed QRS complexes without any clear P waves. An important differential diagnosis is torsades de pointes. Treatment is with cardiopulmonary resuscitation (CPR) and defibrillation. Biphasic defibrillation may be better than monophasic. The medication epinephrine or amiodarone may be given if initial treatments are not effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atrial Flutter
Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia. Atrial flutter is characterized by a sudden-onset (usually) regular abnormal heart rhythm on an electrocardiogram (ECG) in which the heart rate is fast. Symptoms may include a feeling of the heart beating too fast, too hard, or skipping beats, chest discomfort, difficulty breathing, a feeling as if one's stomach has dropped, a feeling of being light-headed, or loss of consciousness. Although this abnormal heart rhythm typically occurs in individuals with cardiovascular disease (e.g. high blood pressure, coronary artery disease, and cardiomyopathy) and diabetes mellitus, it may occur spontaneously in people with otherwise normal hearts. It is typically not a stable rhythm, and often degenerates into atrial fibrillation (AF). But rarely does it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contractility
Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue *Contractile ring in cytokinesis *Contractile vacuole *Muscle contraction **Myocardial contractility *See contractile cell for an overview of cell types in humans. See also *motility Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ... {{SIA Cell movement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myosin
Myosins () are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility. The first myosin (M2) to be discovered was in 1864 by Wilhelm Kühne. Kühne had extracted a viscous protein from skeletal muscle that he held responsible for keeping the tension state in muscle. He called this protein ''myosin''. The term has been extended to include a group of similar ATPases found in the cells of both striated muscle tissue and smooth muscle tissue. Following the discovery in 1973 of enzymes with myosin-like function in '' Acanthamoeba castellanii'', a global range of divergent myosin genes have been discovered throughout the realm of eukaryotes. Although myosin was originally thought to be restricted to muscle cells (hence '' myo-''(s) + '' -in''), there is no single "myosin"; rather it is a very large superfamily of genes whose p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm. An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division. Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell sign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troponin C
Troponin C is a protein which is part of the troponin complex. It contains four calcium-binding EF hands, although different isoforms may have fewer than four functional calcium-binding subdomains. It is a component of thin filaments, along with actin and tropomyosin. It contains an N lobe and a C lobe. The C lobe serves a structural purpose and binds to the N domain of troponin I (TnI). The C lobe can bind either Ca2+ or Mg2+. The N lobe, which binds only Ca2+, is the regulatory lobe and binds to the C domain of troponin I after calcium binding. Isoforms The tissue specific subtypes are: * Slow troponin C, TNNC1 (3p21.1 ) * Fast troponin C, TNNC2 (20q12-q13.11, ) Mutations Point mutations can occur in troponin C inducing alterations to Ca2+ and Mg2+ binding and protein structure, leading to abnormalities in muscle contraction. In cardiac muscle, they are related to dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). These known point mutations are: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Conformation
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers specifically polypeptides formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may also be called a ''residue'' indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein. To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. To understand the functions of proteins at a molecular level, it is often necessary to determine their three-dimensional structure. This is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Action Potential
An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and in some plant cells. Certain endocrine cells such as pancreatic beta cells, and certain cells of the anterior pituitary gland are also excitable cells. In neurons, action potentials play a central role in cell-cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward synaptic boutons situated at the ends of an axon; these signals can then connect with other neurons at synapses, or to motor cells or glands. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of events l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
