PubMed Journals Articles About "Conduction Defects" RSS

15:50 EDT 20th October 2017 | BioPortfolio

Conduction Defects PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest Conduction Defects articles that have been published worldwide.

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Showing "Conduction defects" PubMed Articles 1–25 of 2,300+

Inner Ear Excitation in Normal and Postmastoidectomy Participants by Fluid Stimulation in the Absence of Air- and Bone-Conduction Mechanisms.

Hearing can be induced not only by airborne sounds (air conduction [AC]) and by the induction of skull vibrations by a bone vibrator (osseous bone conduction [BC]), but also by inducing vibrations of the soft tissues of the head, neck, and thorax. This hearing mode is called soft tissue conduction (STC) or nonosseous BC.

Incidence and predictors of sudden death, major conduction defects and sustained ventricular tachyarrhythmias in 1388 patients with myotonic dystrophy type 1.

Divergent and Ultrahigh Thermal Conductivity in Millimeter-Long Nanotubes.

Low-dimensional materials could display anomalous thermal conduction that the thermal conductivity (κ) diverges with increasing lengths, in ways inconceivable in any bulk materials. However, previous theoretical or experimental investigations were plagued with many finite-size effects, rendering the results either indirect or inconclusive. Indeed, investigations on the anomalous thermal conduction must demand the sample length to be sufficiently long so that the phenomena could emerge from unwanted finite-...

The Significance of Internode Length for Saltatory Conduction: Looking Back at the Age of 90.

The development of peripheral nerve fibers involves interdependence between the timing of Schwann cell recruitment during myelination and elongation of the nerve. This adjusts the number and the length of internodes to the length of the fiber. Saltatory conduction in longer nerves involves longer saltations; this makes internode length the factor that determines conduction velocity, thereby adjusting impulse transmission in circuits of different lengths. Myelination increases conduction velocity by means of...

Severe conduction defects requiring permanent pacemaker implantation in patients with a new-onset left bundle branch block after transcatheter aortic valve implantation.

Transcatheter aortic valve implantation (TAVI) is frequently associated with cardiac conduction defects (CCD) requiring permanent pacemaker implantation (PPI). Although new-onset left bundle branch block (LBBB) is often seen, the rate of progression to severe CCD is unclear. We aimed to find clinical and electrocardiographic (ECG) parameters associated with severe CCD requiring PPI in patients with a new-onset LBBB after TAVI and assess its effect on clinical outcome.

Mild hypothermia preserves myocardial conduction during ischemia by maintaining gap junction intracellular communication and sodium channel function.

Acute cardiac ischemia induces conduction velocity (CV) slowing and conduction block, promoting reentrant arrhythmias leading to sudden cardiac arrest (SCA). Previously, we found that mild hypothermia (MH, 32°C) attenuates ischemia-induced conduction block and CV slowing in a canine model of early global ischemia. Acute ischemia impairs cellular excitability and the GJ protein connexin 43 (Cx43). We hypothesized that MH prevented ischemia-induced conduction block and CV slowing by preserving GJ expression ...

Superionic conduction in β-eucryptite: inelastic neutron scattering and computational studies.

β-Eucryptite (LiAlSiO4) is known to show super-ionic conductivity above 700 K. We performed inelastic neutron scattering measurements in β-eucryptite over 300-900 K and calculated the phonon spectrum using classical molecular dynamics (MD) simulations. The MD simulations were used to interpret the inelastic neutron spectra at high temperatures. The calculated diffusion coefficient for Li showed superionic conduction above 1200 K in the perfect crystal. The presence of defects was found to enhance diffusio...

Association Between Local Bipolar Voltage and Conduction Gap Along the Left Atrial Linear Ablation Lesion in Patients With Atrial Fibrillation.

A bipolar voltage reflects a thick musculature where formation of a transmural lesion may be hard to achieve. The purpose of this study was to explore the association between local bipolar voltage and conduction gap in patients with persistent atrial fibrillation (AF) who underwent atrial roof or septal linear ablation. This prospective observational study included 42 and 36 consecutive patients with persistent AF who underwent roof or septal linear ablations, respectively. After pulmonary vein isolation, l...

Theoretical Understanding of Mechanisms of Proton Exchange Membranes Made of 2D Crystals with Ultrahigh Selectivity.

Recent reports on proton conduction across pristine graphene and h-BN provide a new avenue for the design of proton exchange membranes. The uniform pores formed by the electron clouds of 2D crystals can effectively block the undesired transportation of other species thus ultrahigh selectivity can be achieved. With the aid of first-principles calculations, we investigate the proton conduction process across six kinds of intact 2D crystals, namely graphene, h-BN, β12 boron sheet, χ3 boron sheet, phosphorene...

Pediatric mitochondrial diseases and the heart.

Mitochondrial disorders are an increasingly recognized cause of heart dysfunction, with the primary manifestations being cardiomyopathy and conduction defects. This review focuses on the complex genetics of mitochondrial disease and recently discovered conditions that affect mitochondrial function.

Effects of bulk and surface defects on the photocatalytic performance of size-controlled TiO2 nanoparticles.

Defects are one of the crucial factors influencing the photocatalytic activities of TiO2 NPs, as they directly affect the charge separation efficiencies. However, we found that the effect of bulk or surface defects on photocatalytic performance of TiO2 is totally different. Here, we synthesized controllably four kinds of uniform TiO2 NPs, which were used to investigate how the bulk and surface defects influenced the photoactivities of samples with different particle size. Through XPS and EPR analysis, the b...

Electrical transport and thermoelectric properties of boron carbide nanowires.

The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200 to 450 K, there is a crossover between electrical conduction by v...

Macrophages Facilitate Electrical Conduction in the Heart.

Organ-specific functions of tissue-resident macrophages in the steady-state heart are unknown. Here, we show that cardiac macrophages facilitate electrical conduction through the distal atrioventricular node, where conducting cells densely intersperse with elongated macrophages expressing connexin 43. When coupled to spontaneously beating cardiomyocytes via connexin-43-containing gap junctions, cardiac macrophages have a negative resting membrane potential and depolarize in synchrony with cardiomyocytes. Co...

The Molecular and Morphologic Structures That Make Saltatory Conduction Possible in Peripheral Nerve.

Saltatory conduction is the process by which action potentials are rapidly and efficiently propagated along myelinated axons. In the peripheral nervous system, saltatory conduction is made possible by a series of morphologically and molecularly distinct subdomains in both axons and their associated myelinating Schwann cells. This review briefly summarizes current knowledge on the molecular structure and physiology of the node of Ranvier and adjacent regions of the axoglial unit in peripheral nerve.

Size Matters: Defining Critical in Bone Defect Size!

Bone defects are common and are associated with a significant burden of disease. The treatment of these injuries remains controversial, particularly those defects which are critical sized. Despite the need for decision making to be evidence based, a lack of consensus around definitions of critical-sized defects still exists, particularly around those defects in the 1-3 cm range. There is a need to define "critical" in bone defect size because noncritical defects may heal without planned reconstruction and s...

Recombinant human collagen-based microspheres mitigate cardiac conduction slowing induced by adipose tissue-derived stromal cells.

Stem cell therapy to improve cardiac function after myocardial infarction is hampered by poor cell retention, while it may also increase the risk of arrhythmias by providing an arrhythmogenic substrate. We previously showed that porcine adipose tissue-derived-stromal cells (pASC) induce conduction slowing through paracrine actions, whereas rat ASC (rASC) and human ASC (hASC) induce conduction slowing by direct coupling. We postulate that biomaterial microspheres mitigate the conduction slowing influence of ...

Periodic oscillation of ion conduction of nanofluidic diodes using a chemical oscillator.

Periodic ion-conduction oscillation of biological ion channels in a living system is essential for numerous life processes. Here we report an oscillatory nanofluidic system that can self-regulate its ion-conduction states under constant conditions. The oscillatory nanofluidic system is constructed by integrating a chemical oscillator into an artificial single nanochannel system. Oscillating chemical reactions of the pH oscillator carried out inside the nanochannel are used to switch the surface properties o...

Sound wave propagation on the human skull surface with bone conduction stimulation.

Bone conduction (BC) is an alternative to air conduction to stimulate the inner ear. In general, the stimulation for BC occurs on a specific location directly on the skull bone or through the skin covering the skull bone. The stimulation propagates to the ipsilateral and contralateral cochlea, mainly via the skull bone and possibly via other skull contents. This study aims to investigate the wave propagation on the surface of the skull bone during BC stimulation at the forehead and at ipsilateral mastoid.

A novel method for the quantitative determination of defects on graphene surfaces.

In this work, a novel method for the quantitative determination of defects on graphene surfaces has been presented in order to provide accurate, reliable and quantitative information for the defects on graphene products. It was based on the selective adsorption of a specific polar organic ion (Sodium benzenesulfonate) on the edges and defects on graphene surfaces, and the atomic force microscopy (AFM) imaging of the adsorption. By means of an image processing software, the AFM images could be analyzed and t...

Air pollution, neighborhood acculturation factors, and neural tube defects among Hispanic women in California.

Neural tube defects (NTDs) are one of the most common types of birth defects. Environmental pollutants and acculturation have been associated with NTDs independently. The potential effect modification of acculturation in the relationship between ambient air pollution and risks of NTDs is not well understood.

A co-culture microtunnel technique demonstrating a significant contribution of unmyelinated Schwann cells to the acceleration of axonal conduction in Schwann cell-regulated peripheral nerve development.

Schwann cells (SCs) contribute to the regulation of axonal conduction in a myelin-dependent and -independent manner. However, due to the lack of investigative techniques that are able to record axonal conduction under conditions that control the proliferation of specific SC types, little is known about the extent to which myelinated SCs (mSCs) and unmyelinated SCs (umSCs) modulate axonal conduction. In this study, a microtunnel-electrode approach was applied to a neuron/SC co-culture technique. Rat dorsal r...

The Unique Electronic Structure of Mg2 Si: Shaping the Conduction Bands of Semiconductors with Multi-center Bonding.

The electronic structures of the antifluorite-type compound Mg2 Si is described in which a sublattice of short cation-cation contacts creates a very low conduction band minimum. Since Mg2 Si shows n-type conductivity without intentional carrier doping, the present result indicates that the cage defined by the cations plays critical roles in carrier transport similar to those of inorganic electrides, such as 12 CaO⋅7 Al2 O3 :e(-) and Ca2 N. A distinct difference in the location of conduction band minim...

Fluctuations and Topological Defects in Proper Ferroelectric Crystals.

Homotopy theory and first-principles-based effective Hamiltonian simulations are combined to investigate the stability of topological defects in proper ferroelectric crystals. We show that, despite a nearly trivial topology of the order parameter space, these materials can exhibit stable topological point defects in their tetragonal polar phase and stable topological line defects in their orthorhombic polar phase. The stability of such defects originates from a novel mechanism of topological protection rela...

Adenosine administration during hybrid atrial fibrillation ablation to test dormant pulmonary vein conduction.

Adenosine administration after initial pulmonary vein isolation (PVI) reveals dormant conduction and predicts atrial fibrillation (AF) recurrence. Elimination of dormant conduction when present may increase a long-term success rate of AF ablation procedures. There are no studies till date using adenosine to reveal acute reconduction of pulmonary veins (PVs) after epicardial PVI during a hybrid AF ablation procedure.

Diagnostic Value of the Near-Nerve Needle Sensory Nerve Conduction in Sensory Inflammatory Demyelinating Polyneuropathy.

We report here the diagnostic value of the near-nerve needle sensory nerve conduction study (NNN-SNCS) in sensory inflammatory demyelinating polyneuropathy (IDP) in which the routine nerve conduction study was normal or nondiagnostic.

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