Bundle-Branch Block: A form of heart block in which the electrical stimulation of HEART VENTRICLES is interrupted at either one of the branches of BUNDLE OF HIS thus preventing the simultaneous depolarization of the two ventricles.Medial Forebrain Bundle: A complex group of fibers arising from the basal olfactory regions, the periamygdaloid region, and the septal nuclei, and passing to the lateral hypothalamus. Some fibers continue into the tegmentum.Patient Care Bundles: Small sets of evidence-based interventions for a defined patient population and care setting.Plant Vascular Bundle: A strand of primary conductive plant tissue consisting essentially of XYLEM, PHLOEM, and CAMBIUM.Hair Cells, Auditory: Sensory cells in the organ of Corti, characterized by their apical stereocilia (hair-like projections). The inner and outer hair cells, as defined by their proximity to the core of spongy bone (the modiolus), change morphologically along the COCHLEA. Towards the cochlear apex, the length of hair cell bodies and their apical STEREOCILIA increase, allowing differential responses to various frequencies of sound.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Actin Cytoskeleton: Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Stereocilia: Mechanosensing organelles of hair cells which respond to fluid motion or fluid pressure changes. They have various functions in many different animals, but are primarily used in hearing.Hair Cells, Vestibular: Sensory cells in the acoustic maculae with their apical STEREOCILIA embedded in a gelatinous OTOLITHIC MEMBRANE. These hair cells are stimulated by the movement of otolithic membrane, and impulses are transmitted via the VESTIBULAR NERVE to the BRAIN STEM. Hair cells in the saccule and those in the utricle sense linear acceleration in vertical and horizontal directions, respectively.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Microfilament Proteins: Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.Cytoskeleton: The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Microtubules: Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.Electrocardiography: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Hair Cells, Auditory, Inner: Auditory sensory cells of organ of Corti, usually placed in one row medially to the core of spongy bone (the modiolus). Inner hair cells are in fewer numbers than the OUTER AUDITORY HAIR CELLS, and their STEREOCILIA are approximately twice as thick as those of the outer hair cells.Atrioventricular Node: A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.Acoustic Maculae: The sensory areas on the vertical wall of the saccule and in the floor of the utricle. The hair cells in the maculae are innervated by fibers of the VESTIBULAR NERVE.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Cytoplasmic Streaming: The movement of CYTOPLASM within a CELL. It serves as an internal transport system for moving essential substances throughout the cell, and in single-celled organisms, such as the AMOEBA, it is responsible for the movement (CELL MOVEMENT) of the entire cell.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Mechanotransduction, Cellular: The process by which cells convert mechanical stimuli into a chemical response. It can occur in both cells specialized for sensing mechanical cues such as MECHANORECEPTORS, and in parenchymal cells whose primary function is not mechanosensory.Heart Block: Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.Cilia: Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Cochlea: The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Mesophyll Cells: Large and highly vacuolated cells possessing many chloroplasts occuring in the interior cross-section of leaves, juxtaposed between the epidermal layers.Ajmaline: An alkaloid found in the root of RAUWOLFIA SERPENTINA, among other plant sources. It is a class Ia antiarrhythmic agent that apparently acts by changing the shape and threshold of cardiac action potentials.Myosins: A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.Ear, Inner: The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Pseudopodia: A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food.Anterior Cruciate Ligament: A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar eminence of the tibia.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.TurtlesCrystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Phalloidine: Very toxic polypeptide isolated mainly from AMANITA phalloides (Agaricaceae) or death cup; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage.Actinin: A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin.Vinculin: A cytoskeletal protein associated with cell-cell and cell-matrix interactions. The amino acid sequence of human vinculin has been determined. The protein consists of 1066 amino acid residues and its gene has been assigned to chromosome 10.Hemerythrin: A non-heme iron protein consisting of eight apparently identical subunits each containing 2 iron atoms. It binds one molecule of oxygen per pair of iron atoms and functions as a respiratory protein.Hair Cells, Auditory, Outer: Sensory cells of organ of Corti. In mammals, they are usually arranged in three or four rows, and away from the core of spongy bone (the modiolus), lateral to the INNER AUDITORY HAIR CELLS and other supporting structures. Their cell bodies and STEREOCILIA increase in length from the cochlear base toward the apex and laterally across the rows, allowing differential responses to various frequencies of sound.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Organ of Corti: The spiral EPITHELIUM containing sensory AUDITORY HAIR CELLS and supporting cells in the cochlea. Organ of Corti, situated on the BASILAR MEMBRANE and overlaid by a gelatinous TECTORIAL MEMBRANE, converts sound-induced mechanical waves to neural impulses to the brain.Tubulin: A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Protein Folding: Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Subtilisin: A serine endopeptidase isolated from Bacillus subtilis. It hydrolyzes proteins with broad specificity for peptide bonds, and a preference for a large uncharged residue in P1. It also hydrolyzes peptide amides. (From Enzyme Nomenclature, 1992) EC 3.4.21.62.Accessory Atrioventricular Bundle: Extra impulse-conducting tissue in the heart that creates abnormal impulse-conducting connections between HEART ATRIA and HEART VENTRICLES.Hearing: The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Heart Septum: This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.HIV Envelope Protein gp41: Transmembrane envelope protein of the HUMAN IMMUNODEFICIENCY VIRUS which is encoded by the HIV env gene. It has a molecular weight of 41,000 and is glycosylated. The N-terminal part of gp41 is thought to be involved in CELL FUSION with the CD4 ANTIGENS of T4 LYMPHOCYTES, leading to syncytial formation. Gp41 is one of the most common HIV antigens detected by IMMUNOBLOTTING.Flaveria: A plant genus of the family ASTERACEAE that is used for experiments in molecular genetic studies in plant physiology and development.Horseshoe Crabs: An arthropod subclass (Xiphosura) comprising the North American (Limulus) and Asiatic (Tachypleus) genera of horseshoe crabs.Cadaver: A dead body, usually a human body.Self Stimulation: Stimulation of the brain, which is self-administered. The stimulation may result in negative or positive reinforcement.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Circular Dichroism: A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Tachycardia, Atrioventricular Nodal Reentry: Abnormally rapid heartbeats caused by reentry of atrial impulse into the dual (fast and slow) pathways of ATRIOVENTRICULAR NODE. The common type involves a blocked atrial impulse in the slow pathway which reenters the fast pathway in a retrograde direction and simultaneously conducts to the atria and the ventricles leading to rapid HEART RATE of 150-250 beats per minute.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Catheter Ablation: Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.Microtubule-Associated Proteins: High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.Endolymph: The lymph fluid found in the membranous labyrinth of the ear. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Intermediate Filaments: Cytoplasmic filaments intermediate in diameter (about 10 nanometers) between the microfilaments and the microtubules. They may be composed of any of a number of different proteins and form a ring around the cell nucleus.Zea mays: A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Protein Structure, Quaternary: The characteristic 3-dimensional shape and arrangement of multimeric proteins (aggregates of more than one polypeptide chain).Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Regression (Psychology): A return to earlier, especially to infantile, patterns of thought or behavior, or stage of functioning, e.g., feelings of helplessness and dependency in a patient with a serious physical illness. (From APA, Thesaurus of Psychological Index Terms, 1994).Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Anisotropy: A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Pupa: An inactive stage between the larval and adult stages in the life cycle of insects.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Anterior Cruciate Ligament Reconstruction: Rebuilding of the ANTERIOR CRUCIATE LIGAMENT to restore functional stability of the knee. AUTOGRAFTING or ALLOGRAFTING of tissues is often used.Diffusion Tensor Imaging: The use of diffusion ANISOTROPY data from diffusion magnetic resonance imaging results to construct images based on the direction of the faster diffusing molecules.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Cytoskeletal Proteins: Major constituent of the cytoskeleton found in the cytoplasm of eukaryotic cells. They form a flexible framework for the cell, provide attachment points for organelles and formed bodies, and make communication between parts of the cell possible.Tachycardia: Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Organoids: An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.Cytochalasins: 11- to 14-membered macrocyclic lactones with a fused isoindolone. Members with INDOLES attached at the C10 position are called chaetoglobosins. They are produced by various fungi. Some members interact with ACTIN and inhibit CYTOKINESIS.HIV Fusion Inhibitors: Inhibitors of the fusion of HIV to host cells, preventing viral entry. This includes compounds that block attachment of HIV ENVELOPE PROTEIN GP120 to CD4 RECEPTORS.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Phloem: Plant tissue that carries nutrients, especially sucrose, by turgor pressure. Movement is bidirectional, in contrast to XYLEM where it is only upward. Phloem originates and grows outwards from meristematic cells (MERISTEM) in the vascular cambium. P-proteins, a type of LECTINS, are characteristically found in phloem.Chick Embryo: The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.Dimerization: The process by which two molecules of the same chemical composition form a condensation product or polymer.Dihydrostreptomycin Sulfate: A semi-synthetic aminoglycoside antibiotic that is used in the treatment of TUBERCULOSIS.Diffusion Magnetic Resonance Imaging: A diagnostic technique that incorporates the measurement of molecular diffusion (such as water or metabolites) for tissue assessment by MRI. The degree of molecular movement can be measured by changes of apparent diffusion coefficient (ADC) with time, as reflected by tissue microstructure. Diffusion MRI has been used to study BRAIN ISCHEMIA and tumor response to treatment.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Elasticity: Resistance and recovery from distortion of shape.Kinetics: The rate dynamics in chemical or physical systems.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Connective Tissue: Tissue that supports and binds other tissues. It consists of CONNECTIVE TISSUE CELLS embedded in a large amount of EXTRACELLULAR MATRIX.Myosin Type II: The subfamily of myosin proteins that are commonly found in muscle fibers. Myosin II is also involved a diverse array of cellular functions including cell division, transport within the GOLGI APPARATUS, and maintaining MICROVILLI structure.Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Atrial Function: The hemodynamic and electrophysiological action of the HEART ATRIA.Heart Ventricles: The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.Agenesis of Corpus Callosum: Birth defect that results in a partial or complete absence of the CORPUS CALLOSUM. It may be isolated or a part of a syndrome (e.g., AICARDI'S SYNDROME; ACROCALLOSAL SYNDROME; ANDERMANN SYNDROME; and HOLOPROSENCEPHALY). Clinical manifestations include neuromotor skill impairment and INTELLECTUAL DISABILITY of variable severity.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Tachycardia, Paroxysmal: Abnormally rapid heartbeats with sudden onset and cessation.Motion: Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Microscopy, Interference: The science and application of a double-beam transmission interference microscope in which the illuminating light beam is split into two paths. One beam passes through the specimen while the other beam reflects off a reference mirror before joining and interfering with the other. The observed optical path difference between the two beams can be measured and used to discriminate minute differences in thickness and refraction of non-stained transparent specimens, such as living cells in culture.Myofibrils: The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .Microscopy, Video: Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.Nuclear Magnetic Resonance, Biomolecular: NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Posterior Cruciate Ligament: A strong ligament of the knee that originates from the anterolateral surface of the medial condyle of the femur, passes posteriorly and inferiorly between the condyles, and attaches to the posterior intercondylar area of the tibia.Ganglion Cysts: Nodular tumor-like lesions or mucoid flesh, arising from tendon sheaths, LIGAMENTS, or JOINT CAPSULE, especially of the hands, wrists, or feet. They are not true cysts as they lack epithelial wall. They are distinguished from SYNOVIAL CYSTS by the lack of communication with a joint cavity or the SYNOVIAL MEMBRANE.Protein Multimerization: The assembly of the QUATERNARY PROTEIN STRUCTURE of multimeric proteins (MULTIPROTEIN COMPLEXES) from their composite PROTEIN SUBUNITS.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Intercellular Junctions: Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)Tachycardia, Ventricular: An abnormally rapid ventricular rhythm usually in excess of 150 beats per minute. It is generated within the ventricle below the BUNDLE OF HIS, either as autonomic impulse formation or reentrant impulse conduction. Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide QRS complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (AV dissociation).Coronary Sinus: A short vein that collects about two thirds of the venous blood from the MYOCARDIUM and drains into the RIGHT ATRIUM. Coronary sinus, normally located between the LEFT ATRIUM and LEFT VENTRICLE on the posterior surface of the heart, can serve as an anatomical reference for cardiac procedures.Membrane Fusion: The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.Actomyosin: A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Bacterial Proteins: Proteins found in any species of bacterium.Cell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Plant Epidermis: A thin layer of cells forming the outer integument of seed plants and ferns. (Random House Unabridged Dictionary, 2d ed)Ophthalmic Nerve: A sensory branch of the trigeminal (5th cranial) nerve. The ophthalmic nerve carries general afferents from the superficial division of the face including the eyeball, conjunctiva, upper eyelid, upper nose, nasal mucosa, and scalp.Muscles: Contractile tissue that produces movement in animals.Phosphoenolpyruvate Carboxylase: An enzyme with high affinity for carbon dioxide. It catalyzes irreversibly the formation of oxaloacetate from phosphoenolpyruvate and carbon dioxide. This fixation of carbon dioxide in several bacteria and some plants is the first step in the biosynthesis of glucose. EC 4.1.1.31.Biopolymers: Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.Molecular Motor Proteins: Proteins that are involved in or cause CELL MOVEMENT such as the rotary structures (flagellar motor) or the structures whose movement is directed along cytoskeletal filaments (MYOSIN; KINESIN; and DYNEIN motor families).Photosynthesis: The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)Actin-Related Protein 2-3 Complex: A complex of seven proteins including ARP2 PROTEIN and ARP3 PROTEIN that plays an essential role in maintenance and assembly of the CYTOSKELETON. Arp2-3 complex binds WASP PROTEIN and existing ACTIN FILAMENTS, and it nucleates the formation of new branch point filaments.Cytochalasin B: A cytotoxic member of the CYTOCHALASINS.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Contractile Proteins: Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.Oxidopamine: A neurotransmitter analogue that depletes noradrenergic stores in nerve endings and induces a reduction of dopamine levels in the brain. Its mechanism of action is related to the production of cytolytic free-radicals.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Catheter-Related Infections: Infections resulting from the use of catheters. Proper aseptic technique, site of catheter placement, material composition, and virulence of the organism are all factors that can influence possible infection.Vectorcardiography: Recording of the moment-to-moment electromotive forces of the heart on a plane of the body surface delineated as a vector function of time.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Wolff-Parkinson-White Syndrome: A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulses are abnormally conducted to the HEART VENTRICLES via an ACCESSORY CONDUCTING PATHWAY that is located between the wall of the right or left atria and the ventricles, also known as a BUNDLE OF KENT. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.Cardiac Resynchronization Therapy: The restoration of the sequential order of contraction and relaxation of the HEART ATRIA and HEART VENTRICLES by atrio-biventricular pacing.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.Cytochalasin D: A fungal metabolite that blocks cytoplasmic cleavage by blocking formation of contractile microfilament structures resulting in multinucleated cell formation, reversible inhibition of cell movement, and the induction of cellular extrusion. Additional reported effects include the inhibition of actin polymerization, DNA synthesis, sperm motility, glucose transport, thyroid secretion, and growth hormone release.Gelsolin: A 90-kDa protein produced by macrophages that severs ACTIN filaments and forms a cap on the newly exposed filament end. Gelsolin is activated by CALCIUM ions and participates in the assembly and disassembly of actin, thereby increasing the motility of some CELLS.Amino Acid Motifs: Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.Muscle Fibers, Skeletal: Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Protein Stability: The ability of a protein to retain its structural conformation or its activity when subjected to physical or chemical manipulations.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Epithelium: One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Nursing, Team: Coordination of nursing services by various nursing care personnel under the leadership of a professional nurse. The team may consist of a professional nurse, nurses' aides, and the practical nurse.Cell Surface Extensions: Specialized structures of the cell that extend the cell membrane and project out from the cell surface.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Elastic Tissue: Connective tissue comprised chiefly of elastic fibers. Elastic fibers have two components: ELASTIN and MICROFIBRILS.Heart: The hollow, muscular organ that maintains the circulation of the blood.Tectorial Membrane: A membrane, attached to the bony SPIRAL LAMINA, overlying and coupling with the hair cells of the ORGAN OF CORTI in the inner ear. It is a glycoprotein-rich keratin-like layer containing fibrils embedded in a dense amorphous substance.Structural Homology, Protein: The degree of 3-dimensional shape similarity between proteins. It can be an indication of distant AMINO ACID SEQUENCE HOMOLOGY and used for rational DRUG DESIGN.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Spindle Apparatus: A microtubule structure that forms during CELL DIVISION. It consists of two SPINDLE POLES, and sets of MICROTUBULES that may include the astral microtubules, the polar microtubules, and the kinetochore microtubules.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Mechanical Processes: The behaviors of materials under force.Birefringence: The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)Chloroplasts: Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.Myosin Type III: A subclass of myosins originally found in the photoreceptor of DROSOPHILA. The heavy chains can occur as two alternatively spliced isoforms of 132 and 174 KDa. The amino terminal of myosin type III is highly unusual in that it contains a protein kinase domain which may be an important component of the visual process.Otolithic Membrane: A gelatinous membrane overlying the acoustic maculae of SACCULE AND UTRICLE. It contains minute crystalline particles (otoliths) of CALCIUM CARBONATE and protein on its outer surface. In response to head movement, the otoliths shift causing distortion of the vestibular hair cells which transduce nerve signals to the BRAIN for interpretation of equilibrium.Alamethicin: A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.
Hierarchy of ventricular pacemakers. (1/251)
To characterize the pattern of pacemaker dominance in the ventricular specialized conduction system (VSCS), escape ventricular pacemakers were localized and quantified in vivo and in virto, in normal hearts and in hearts 24 hours after myocardial infarction. Excape pacemaker foci were localized in vivo during vagally induced atrial arrest by means of electrograms recorded from the His bundle and proximal bundle branches and standard electrocardiographic limb leads. The VSCS was isolated using a modified Elizari preparation or preparations of each bundle branch. Peacemakers were located by extra- and intracellular recordings. Escape pacemaker foci in vivo were always in the proximal conduction system, usually the left bundle branch. The rate was 43+/-11 (mean+/-SD) beats/min. After beta-adrenergic blockade, the mean rate fell to 31+/-10 beats/min, but there were no shifts in pacemaker location. In the infarcted hearts, pacemakers were located in the peripheral left bundle branch. The mean rate was 146+/-20 beats/min. In isolated normal preparations, the dominant pacemakers usually were in the His bundle, firing at a mean rate of 43+/-10 beats/min. The rates of pacemakers diminished with distal progression. In infarcted hearts, the pacemakers invariably were in the infarct zone. The mean firing rates were not influenced by beta-adrenergic blockade. The results indicate that the dominant pacemakers are normally in the very proximal VSCS, but after myocardial infarction pacemaker dominance is shifted into the infarct. Distribution of pacemaker dominance is independent of sympathetic influence. (+info)Modulation of AV nodal and Hisian conduction by changes in extracellular space. (2/251)
Previous studies have demonstrated that the extracellular space (ECS) component of the atrioventricular (AV) node and His bundle region is larger than the ECS in adjacent contractile myocardium. The potential physiological significance of this observation was examined in a canine blood-perfused AV nodal preparation. Mannitol, an ECS osmotic expander, was infused directly into either the AV node or His bundle region. This resulted in a significant dose-dependent increase in the AV nodal or His-ventricular conduction time and in the AV nodal effective refractory period. Mannitol infusion eventually resulted in Wenckebach block (n = 6), which reversed with mannitol washout. The ratio of AV nodal to left ventricular ECS in tissue frozen immediately on the development of heart block (n = 8) was significantly higher in the region of block (4.53 +/- 0.61) compared with that in control preparations (2.23 +/- 0.35, n = 6, P < 0.01) and donor dog hearts (2.45 +/- 0.18, n = 11, P < 0.01) not exposed to mannitol. With lower mannitol rates (10% of total blood flow), AV nodal conduction times increased by 5-10% and the AV node became supersensitive to adenosine, acetylcholine, and carbachol, but not to norepinephrine. We conclude that mannitol-induced changes in AV node and His bundle ECS markedly alter conduction system electrophysiology and the sensitivity of conductive tissues to purinergic and cholinergic agonists. (+info)LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes. (3/251)
BACKGROUND: Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate if a systematic lesion pattern is required in the treatment of complex arrhythmogenic substrates. METHODS AND RESULTS: We developed a new technique for online 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy within the right atrium, right ventricle, and left ventricle by comparing measured and true interelectrode distances of a decapolar catheter. Long-term stability was analyzed by localization of the most proximal His bundle before and after slow pathway ablation. Electrogram recordings were unaffected by the applied electrical field. Localization data from 3 catheter positions, widely distributed within the right atrium, right ventricle, or left ventricle, were analyzed in 10 patients per group. The relationship between measured and true electrode positions was highly linear, with an average correlation coefficient of 0.996, 0.997, and 0.999 for the right atrium, right ventricle, and left ventricle, respectively. Localization accuracy was better than 2 mm, with an additional scaling error of 8% to 14%. After 2 hours, localization of the proximal His bundle was reproducible within 1.4+/-1.1 mm. CONCLUSIONS: This new technique enables accurate and reproducible real-time localization of electrode positions in cardiac mapping and ablation procedures. Its application does not distort the quality of electrograms and can be applied to any electrode catheter. (+info)Reversion to sinus rhythm 11 years after surgically induced heart block. (4/251)
A patient is presented in whom the heart reverted spontaneously to sinus rhythm 11 years after surgical closure of a ventricular septal defect complicated by complete heart block. It seems unlikely that regeneration of fibres in the bundle of His, if these had indeed been destroyed, could account for the restoration of sinus rhythm after so long an interval. (+info)Electrophysiological effects of mexiletine in man. (5/251)
The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node. (+info)Chronic His bundle block. Clinical, electrocardiographic, electrophysiological, and follow-up studies on 16 patients. (6/251)
This report describes 16 patients with block within the His bundle seen over a period of 55 months. Ten were women and 6 men, with an average age of 76 years, range, 42 to 98 years. All patients had His bundle recordings showing split His bundle potentials (H and H) (13 patients) or narrow QRS with block distal to the His bundle potential (3 patients). Of the 16 patients, 10 had complete heart block, 4 second degree AV block (2 patients with Mobitz type II, and 2 with 2:1), and 2 first degree AV block. Ten patients had a narrow QRS in the conducted beats or escape rhythms. Intravenous atropine (1 to 2 mg) had a variable effect on AV conduction and the rate of the escape rhythm. Twelve patients have had a permanent pacemaker implanted. During the follow-up period, 10 patients died 1 to 31 months from the time of initial examination. The remaining 6 patients (5 with pacemaker) are alive 3 to 58 months later. (+info)Living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrhythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. (7/251)
Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature. (+info)Double component action potentials in the posterior approach to the atrioventricular node: do they reflect activation delay in the slow pathway? (8/251)
OBJECTIVES: The aim of the study was to elucidate the mechanism of double component action potentials in the posterior approach to the atrioventricular (AV) junctional area. BACKGROUND: Double component action potentials are often associated with activation delay and therefore might be a marker of the location of the so-called slow pathway. METHODS: The AV junction was scanned for double component action potentials in Langendorff perfused pig and dog hearts, using conventional microelectrode recordings. Characteristics of these action potentials were investigated during basic and premature stimulation and cooling of the anterior approach to the node. RESULTS: During basic stimulation, double component action potentials were recorded in 19 out of 20 hearts. In 74% of these cases, the second component occurred before the His deflection. During premature stimulation this percentage was 50%, while delay between the two components always increased. In 80% of the cases, the amplitude of the two components became <20 mV during progressive shortening of the coupling interval. The first component was generated by activation in superficial layers, the second one by activation in deeper layers. Cooling of the anterior region revealed that the second component was caused by activation arriving from the anterior region. CONCLUSIONS: Double component action potentials in the posterior approach to the AV node are generated by the asynchronous arrival of wave fronts in different, weakly coupled layers or by the summation of asynchronously arriving wave fronts. They are not always associated with activation delay in the slow pathway. (+info)
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Electroanatomically estimated length of slow pathway in atrioventricular nodal reentrant tachycardia - pdf descargarUsing bundles in health care[edit]. Using bundles in health care simplifies the complex processes of the care of patients with ... A bundle is a selected set of elements of care distilled from evidence-based practice guidelines that, when implemented as a ... The 24-hour SSC Management Bundle includes: *Low-dose steroids administered for septic shock in accordance with a standardized ... Each hospital's sepsis protocol may be customized, but it must meet the standards created by the bundle. ...
A line bundle, such as the tangent bundle of S1 is trivial if and only if there is a section that vanishes nowhere, see ... the trivial bundle X × V). For example, the Möbius strip can be seen as a line bundle over the circle S1 (by identifying open ... to the trivial bundle U × V → U. Despite their locally trivial character, vector bundles may (depending on the shape of the ... The case dim V = 1 is called a line bundle. For any vector space V, the projection X × V → X makes the product X × V into a " ...
Home Bundle Edition[edit]. National Instruments provides a low cost LabVIEW Home Bundle Edition.[9] ... "LabVIEW Home Bundle for Windows - National Instruments". sine.ni.com. Archived from the original on 2016-07-04.. ...
Service bundling[edit]. For residential users, IPTV is often provided in conjunction with video on demand and may be bundled ... Commercial bundling of IPTV, VoIP and Internet access is sometimes referred to in marketing as triple play service. When these ...
Remak bundles[edit]. C fiber axons are grouped together into what is known as Remak bundles.[3] These occur when a non- ... The condition of Remak bundles varies with age.[4] The number of C fiber axons in each Remak bundle varies with location.[3] ... Remak bundles in the distal peripheral nerve are clustered with other Remak bundles.[3] The Remak Schwann cells have been shown ... Multiple neurons contribute axons to the Remak bundle with an average ratio of about 2 axons contributed per bundle.[3] The ...
See also: Wikipedia:Citing sources § Bundling citations. Template {{harvnb}}. can be used to bundle citations. {{sfnm}}. also ... is inappropriate for bundled citations; use {{harvnb}}. or {{sfnm}}. . More exotic Harvard citations {{harvid}}. or {{harvs}}. ...
Bundled and/or integrated software[edit]. *Microsoft Chat 2.0 is a simple text chatting program included in the Windows NT-line ... It was bundled with Internet Explorer 4, but was also available for free, and could be downloaded from online repositories.[17] ... At the same event, Apple announced the release of Mac OS 8.1, which would be bundled with IE4. ...
... holds that the self cannot be reduced to a bundle because the concept of a self is incompatible with the idea of a bundle. ... Bundle theory of the self[edit]. A Treatise Of Human Nature: Being An Attempt To Introduce The Experimental Method Of Reasoning ... James Giles, a principal exponent of this view, argues that the no-self or eliminativist theory and the bundle or reductionist ... When we start introspecting, "we are never intimately conscious of anything but a particular perception; man is a bundle or ...
There are several types of bundles: pure bundles where the goods can only be purchased as package or mixed bundles where the ... Price bundling (also known as product bundling) occurs where two or more products or services are priced as a package with a ... These include price skimming, price discrimination and yield management, price points, psychological pricing, bundle pricing, ... The prices of the bundle is typically less than when the two items are purchased separately.[24] ...
Bundle from Middle Dutch bondel or perhaps a merger of this word and Old English byndele (binding) [37]. Bung from Middle Dutch ...
... passes through the atrioventricular node down into the bundle of His and into the Purkinje fibers, spreading down and to the ... such as a bundle branch block that alters the shape of the QRS complexes. ECGs can be interpreted in isolation but should be ...
"Bundle of Ivory". January 7, 2003 (2003-01-07). 16. "Ivory Returns". January 8, 2003 (2003-01-08). ...
Bundle, M.W; Dial, K.P. (2003). "Mechanics of wing-assisted incline running (WAIR)" (PDF). The Journal of Experimental Biology ...
Wolinetz, Geoff (June 24, 2010). "Brain Pickings blogger Maria Popova: 'I'm not a big believer in saving'". Bundle. Archived ...
Bundled citation: {{harvnb}}. or {{sfnm}}. [ویرایش]. نوشتار(های) وابسته: Wikipedia:Citing sources § Bundling citations ... is inappropriate for bundled citations; use {{harvnb}}. or {{sfnm}}. . More exotic Harvard citations {{harvid}}. or {{harvs}}. ...
Usually the deep purple roots of beetroot are eaten boiled, roasted or raw, and either alone or combined with any salad vegetable. A large proportion of the commercial production is processed into boiled and sterilized beets or into pickles. In Eastern Europe, beet soup, such as borscht, is a popular dish. In Indian cuisine, chopped, cooked, spiced beet is a common side dish. Yellow-coloured beetroots are grown on a very small scale for home consumption.[9]. The green, leafy portion of the beet is also edible. The young leaves can be added raw to salads, whilst the adult leaves are most commonly served boiled or steamed, in which case they have a taste and texture similar to spinach. Those greens selected should be from bulbs that are unmarked, instead of those with overly limp leaves or wrinkled skins, both of which are signs of dehydration. The domestication of beets can be traced to the emergence of an allele which enables biennial harvesting of leaves and taproot.[10]. Beetroot can be boiled ...
"Full Lima Bundle Released". lpmuds.net. 2009-01-24. Retrieved 2010-05-17.. ...
"Avicii Sets Mark; A Bundle of Brit." Billboard 21 December 2013: 181. ProQuest. Web. 5 October 2015 ...
Shortly after the iPhone 4 was launched, some consumers reported that signal strength of the phone was reduced when touching the lower left edge of the phone, bridging one of the two locations which separates the two antennas, resulting in dropped calls in some areas with lower signal reception.[85][86][87] In response, Apple issued a statement advising that customers should "avoid gripping [the phone] in the lower left corner" when making or receiving a call.[88] As a consequence of this problem, it was reported on July 2, 2010 that several iPhone 4 users were planning on suing Apple and AT&T for fraud by concealment, negligence, intentional misrepresentation and defective design. The legal challenge was started by a law firm, who set up a website to recruit disenchanted iPhone 4 buyers for a lawsuit against Apple.[89][90] Later that day, Apple issued another statement stating that it had discovered the cause of the "dramatic drop in bars".[91] Apple explained how the formula it used to ...
The CAUTI Bundle is similar to the bundles for prevention and treatment of ventilator-associated pneumonia, sepsis, and central ... "Safeek UTI Bundle" (PDF). American College of Physician Executives. Retrieved 2010-04-01. Safeek, Yisrael. "UTI Bundle". ... Safeek published a simple, easy-to-remember urinary tract infections open source bundle (CAUTI Bundle) in Physician Executive, ... The CAUTI Bundle was later reprinted by Healthcare Financial Management Journal upon request as a tool to decrease unnecessary ...
Bundle review. Rumbler, Bill (March 28, 1993). "YOUR 2 CENTS WORTH". Chicago Sun-Times. Retrieved 16 November 2013. ...
"VTG match worn late 80s Kelantan FA". Kutipan Bundle. 13 May 2016. Retrieved 14 January 2017. "Kelantan FA football shirts". ...
... "bundle; (fig.) term of endearment for infants, 'little mite'; (in some dial.) short and/or plump woman"; knytt, dialectical ...
"Humble Bundle: Sci-fi Classics". Humble Bundle. Archived from the original on February 18, 2016. Retrieved July 10, 2016. "Wild ... Brick Tower Press offered e-book versions of its titles, including Deuces Down and Death Draws Five, via Humble Bundle in ...
"Life in Bunker features". Humble Bundle. Retrieved 24 April 2016. Markley, John (1 March 2016). "Life In Bunker Review - Deep ...
I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood ... I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood ...
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Bundle of His | anatomy | Britannica.com... known as the bundle of His) running along the muscular partition between the left and right chambers of the heart. He found ... Other articles where Bundle of His is discussed: Wilhelm His: …muscle fibres ( ... to the atrioventricular node and bundle of His (known as the atrioventricular junctional tissue), through the bundle branches ... Alternative Title: atrioventricular bundle. Learn about this topic in these articles:. discovery by His. * In Wilhelm His. … ...
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What is the definition of bundle branch?bundle branch is a part of the electrical pathway of the heart that delivers electrical impulses to the ventricles of the heart ... What is the definition of bundle branch?. ANSWER Bundle branch is a part of the electrical pathway of the heart that delivers ...
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- B.S. Kiranagi,Lie algebra bundles and Lie rings, Proc. (wikipedia.org)
- B.S.Kiranagi, Semi simple Lie algebra bundles, Bull. (wikipedia.org)
- B.S.Kiranagi and G.Prema, Cohomology of Lie algebra bundles and its applications, Ind. (wikipedia.org)
- B.S.Kiranagi and G.Prema, Lie algebra bundles defined by Jordan algebra bundles, Bull. (wikipedia.org)
- B.S.Kiranagi, G.Prema and C.Chidambara, Rigidity theorem for Lie algebra Bundles, Communications in Algebra 20 (6), 1992, pp. 1549 - 1556. (wikipedia.org)
- muscle fibres (known as the bundle of His) running along the muscular partition between the left and right chambers of the heart. (britannica.com)
- of conductive fibres called the bundle of His, which induces the contraction of the ventricles. (britannica.com)
- to the atrioventricular node and bundle of His (known as the atrioventricular junctional tissue), through the bundle branches and Purkinje fibres (known as the ventricular conduction system), and into the ventricular muscle cells that ultimately generate cardiac output. (britannica.com)
- A.Douady et M.Lazard, Espaces fibres en algebre de Lie et en groups, Invent. (wikipedia.org)
- Let ρ:TP/G→M be the projection onto M. The fibres of the bundle TP/G under the projection ρ carry an additive structure. (wikipedia.org)
- The triple (TE, p∗, TM) becomes a smooth vector bundle with these vector space operations on its fibres. (wikipedia.org)
- Thus, the set of the isomorphism classes of all line bundles on some topological space X forms an abelian group called the Picard group of X. One can also define a symmetric power and an exterior power of a vector bundle in a similar way. (wikipedia.org)
- The left bundle is a part of the heart's electrical conduction system and block in the bundle branch can occur for a number of reasons. (medhelp.org)
- In the heart's conduction system, Bachmann's bundle (also called the Bachmann bundle or the interatrial tract) is a branch of the anterior internodal tract that resides on the inner wall of the left atrium. (wikipedia.org)
- Besides Bachmann's bundle, the other three conduction tracts that constitute the atrial conduction system are known as the anterior, middle, and posterior tracts, which run from the sinoatrial node to the atrioventricular node, converging in the region near the coronary sinus. (wikipedia.org)
- The bundle branches were separately described by Retzer and Braeunig as early as 1904, but their physiological function remained unclear and their role in the electrical conduction system of the heart remained unknown until Sunao Tawara published his monograph on Das Reizleitungssystem des Säugetierherzens (English: The Conduction System of the Mammalian Heart) in 1906. (wikipedia.org)
- As part of the electrical conduction system of the heart, it transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the bundle branches. (wikipedia.org)
- The bundle of His is an important part of the electrical conduction system of the heart, as it transmits impulses from the atrioventricular node, located at the inferior end of the interatrial septum, to the ventricles of the heart. (wikipedia.org)
- The ventricular conduction system comprises the bundle branches and the Purkinje networks. (wikipedia.org)
- Trivial line bundles can have several flat bundle structures. (wikipedia.org)
- Line bundles are both I-bundles and vector bundles of rank one. (wikipedia.org)
- Vector bundles of rank 1 are called line bundles, while those of rank 2 are less commonly called plane bundles. (wikipedia.org)
- that is, when (E, g) is a Riemannian or pseudo-Riemannian vector bundle. (wikipedia.org)
- For concreteness, suppose that (E, g) is a Riemannian vector bundle. (wikipedia.org)
- Examples include the tensor-algebra bundle, exterior bundle, and symmetric bundle associated to a given vector bundle, as well as the Clifford bundle associated to any Riemannian vector bundle. (wikipedia.org)
- If the base space X is paracompact and Hausdorff then a real, finite-rank vector bundle E and its dual E∗ are isomorphic as vector bundles. (wikipedia.org)
- Two vector bundles with isomorphic associated gradeds are called S-equivalent. (wikipedia.org)
- This can be seen by considering the pullback of E over F(E) → M, which is isomorphic to the trivial bundle F(E) × Rk. (wikipedia.org)
- Taking ti to be constant functions to the identity in G, we see that two fiber bundles with the same base, fiber, structure group, trivializing neighborhoods, and transition functions are isomorphic. (wikipedia.org)
- I-bundles over the Klein-Bottle, "elementary" work on the orientable I-bundle over K, by Maria Rita Casali, Dipartimento di Matematica Pura e Applicata, Università di Modena e Reggio Emilia. (wikipedia.org)
- Orientable surfaces have principal unit tangent bundles. (wikipedia.org)
- https://mathoverflow.net/questions/144092/is-every-orientable-circle-bundle-principal. (wikipedia.org)
- A vector bundle that can be given an orientation is called an orientable vector bundle. (wikipedia.org)
- Each video in this series, Patient-Centered Rounds Using the ABCDEF Bundle, shows examples of patient care rounds. (youtube.com)
- PlanetMath page of universal bundle examples J. J. Duistermaat and J. A. Kolk,-- Lie Groups, Universitext, Springer. (wikipedia.org)
- Other examples of four-helix bundles include cytochrome, ferritin, human growth hormone, cytokine, and Lac repressor C-terminal. (wikipedia.org)
- Examples of bundles that contain executable code include applications, frameworks, and plugins. (wikipedia.org)
- Examples of bundles that do not contain executable code include document packages (iWork documents) and media libraries (iPhoto Library). (wikipedia.org)
- Community land trusts and land banking are examples of efforts to rearrange the bundle of rights. (wikipedia.org)
- While many well-known examples of bundling are all products or services from the same store or provider, such as the sports package for a car or a grocery store's gift basket, in some cases, cross-industry bundles are assembled and sold. (wikipedia.org)
- Let π : E → X be a fiber bundle over a topological space X with structure group G and typical fibre F. By definition, there is a left action of G (as a transformation group) on the fibre F. Suppose furthermore that this action is effective. (wikipedia.org)
- Let E → X be a real vector bundle of rank k over a topological space X. A frame at a point x ∈ X is an ordered basis for the vector space Ex. (wikipedia.org)
- The double tangent bundle is a double vector bundle. (wikipedia.org)
- Note that the connector map is automatically linear with respect to the tangent bundle structure (TE, πTE, E). Connection (vector bundle) Double tangent bundle Ehresmann connection Vector bundle P.Michor. (wikipedia.org)
- The Frank Zappa AAAFNRAA Birthday Bundle was released as a digital download on iTunes on December 15, 2006. (wikipedia.org)
- It is the second iTunes album by Frank Zappa, the first being The Frank Zappa AAAFNRAA Birthday Bundle (2006). (wikipedia.org)
- If E is a real vector bundle of rank n, then a choice of metric on E amounts to a reduction of the structure group to the orthogonal group O(n). (wikipedia.org)
- Classifying space for U(n) Chern class tautological bundle, a universal bundle for the general linear group. (wikipedia.org)
- Because of this, the tautological bundle is important in the study of characteristic classes. (wikipedia.org)
- All that can stop the definition of the tautological bundle from this indication, is the (pedantic) difficulty that the Vg are going to intersect. (wikipedia.org)
- By convention and use P(V) may usefully carry the tautological bundle in the dual space sense. (wikipedia.org)
- We define the tautological bundle γn, k over Gn(Rn+k) as follows. (wikipedia.org)
- Taking the direct limit of the bundles γn, k gives the tautological bundle γn of Gn. (wikipedia.org)
- sr] which gives a map from X to Pr, and the pullback of the dual of the tautological bundle under this map is L. In this way, projective space acquires a universal property. (wikipedia.org)
- Conduction down the left bundle branch proceeds normally, and the interventricular septum and left ventricle rapidly depolarize in the normal fashion. (medscape.com)
- The left bundle branch further divides into the left anterior fascicles and the left posterior fascicles. (wikipedia.org)
- Other sources divide the left bundle branch into three fascicles: the left anterior, the left posterior, and the left septal fascicle. (wikipedia.org)
- In this case only the anterior half of the left bundle branch (fascicle) is involved Left posterior fascicular block. (wikipedia.org)
- The left ventricle however, is still normally activated by the left bundle branch. (wikipedia.org)
- There are also partial blocks of the left bundle branch: "left anterior fascicular block" (LAFB) and a "left posterior fascicular block" (LPFB). (wikipedia.org)
- This refers to the bifurcation of the left bundle branch. (wikipedia.org)
- Like other tensor operations, this construction can be carried out fiberwise on a smooth vector bundle. (wikipedia.org)
- Tensor bundles of E can be constructed in a similar manner. (wikipedia.org)