Propagation Of Electrical Signals Research Articles

Abstract 13878: Activated Fibroblasts and IL-1β Mediate Fibrotic Cardiac Remodeling Observed in Premature Ventricular Contraction-Induced Cardiomyopathy

Introduction: The relevance of fibrosis in premature ventricular contraction-induced cardiomyopathy (PVC-CM) remains unclear. Recent studies suggest that fibrosis promotes adverse extracellular matrix (ECM) remodeling that has been implicated in arrhythmogenesis. However, fibrotic areas and fibroblast activation have not been characterized in PVC-CM. The objective of this study was to assess cardiac remodeling by collagen fiber deposition, fibroblast activation (using αSMA as a marker), and the pro-fibrotic cytokine IL-1β level in LV myocardium. Hypothesis: Activation of fibroblasts promotes adverse cardiac remodeling in PVC-CM. Methods: Modified pacemakers were implanted in canines, half of them developing PVC-CM after 12 weeks of bigeminal PVCs (50% burden at 200-220 ms coupling interval), while the remaining were not exposed to PVCs (sham). Paraffin-embedded or simple formalin-fixed cardiac samples were sectioned and stained with Sirius Red/Fast Green (SR/FG) or immunofluorescence (IF) to assess collagen fiber deposits and αSMA content, respectively. Expression of IL-1β and αSMA were assessed by Western blot. Results: The percentage of fibrosis was three times greater in PVC-CM tissues compared to sham (10.2 ± 0.98 vs 3.3 ± 0.53, p = 0.014), consistent with an increase in αSMA (1 ± 0.08 vs 1.93 ±0.33, p < 0.05) and IL-1β expression (1 ± 0.09 vs 1.69 ± 0.11, p < 0.01). The figure shows differences in collagen fibers with SR/FG and αSMA with IF in (A) sham and (B) PVC-CM. Increased αSMA and IL-1β support the hypothesis that fibroblast activation is a key component in the PVC-CM phenotype. Conclusion: These findings strongly suggest that fibroblast activation during PVCs promote ECM expansion causing persistent structural remodeling which may disrupt electrical signal propagation and potentially contribute to arrhythmogenesis and worsening ventricular function associated with PVC-CM.

Piezotronic effect determined neuron-like differentiation of adult stem cells driven by ultrasound

Electrical stimulation is an efficient approach to inducing neural differentiation of stem cells. However, most demonstrations of conventional electrical stimulation for the regulation of stem cell differentiation generally involve three components—an electrical signal generator, conductive culture substrate, and pair of lines, which limits its use in clinical applications for neural degeneration treatments. Herein, we proposed a facile method to generate localized electrical signals on the surface of a piezoelectric poly (vinylidene fluoride) (PVDF) film with a well-designed nanopillar array driven by ultrasound irradiation based on a piezotronic effect, which proved to induce neuronal differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) without any biological or chemical neural inducing factors. The assessment of rBMSCs on the surface of the PVDF nanopillar array at the gene and protein levels confirmed that rBMSCs could differentiate into neuron-like cells. This demonstration provides a practical approach for the regulation of adult stem cells to differentiate into neurons, which will be a great achievement to overcome the shortage of neural stem cells in the adult human body and realize the autologous stem cell treatment of neurodegeneration. This work creates a new therapeutic avenue for contactless, controlled neuroregenerative therapies.

Microvascular changes that stagger the mind.

Hypertension is a leading cause of cognitive impairment and dementias. Such loss of brain health has a vascular component, but the mechanisms involved are poorly defined. In this issue of the JCI, Koide et al. provide evidence that end-organ effects of hypertension on capillary endothelium and inward-rectifier K+ channels (Kir2.1) impair integrated propagation of electrical signals and vasodilation upstream, resulting in reduced neurovascular coupling (NVC) despite neural activation. NVC was partly restored by amlodipine, but not losartan. Moreover, NVC was improved by eplerenone in the presence of losartan, suggesting a role for aldosterone. These findings support the concept that endothelial cells and Kir2.1 are potential therapeutic targets to prevent or reverse the loss of NVC and the vascular component of cognitive deficits that occur with increased frequency during hypertension.

Emulating Dendritic Computing Paradigms on Analog Neuromorphic Hardware

BrainScaleS-2 is an accelerated and highly configurable neuromorphic system with physical models of neurons and synapses. Beyond networks of spiking point neurons, it allows for the implementation of user-defined neuron morphologies. Both passive propagation of electric signals between compartments as well as dendritic spikes and plateau potentials can be emulated. In this paper, three multi-compartment neuron morphologies are chosen to demonstrate passive propagation of postsynaptic potentials, spatio-temporal coincidence detection of synaptic inputs in a dendritic branch, and the replication of the BAC burst firing mechanism found in layer 5 pyramidal neurons of the neocortex.

Electrical Signals, Plant Tolerance to Actions of Stressors, and Programmed Cell Death: Is Interaction Possible?

In environmental conditions, plants are affected by abiotic and biotic stressors which can be heterogenous. This means that the systemic plant adaptive responses on their actions require long-distance stress signals including electrical signals (ESs). ESs are based on transient changes in the activities of ion channels and H+-ATP-ase in the plasma membrane. They influence numerous physiological processes, including gene expression, phytohormone synthesis, photosynthesis, respiration, phloem mass flow, ATP content, and many others. It is considered that these changes increase plant tolerance to the action of stressors; the effect can be related to stimulation of damages of specific molecular structures. In this review, we hypothesize that programmed cell death (PCD) in plant cells can be interconnected with ESs. There are the following points supporting this hypothesis. (i) Propagation of ESs can be related to ROS waves; these waves are a probable mechanism of PCD initiation. (ii) ESs induce the inactivation of photosynthetic dark reactions and activation of respiration. Both responses can also produce ROS and, probably, induce PCD. (iii) ESs stimulate the synthesis of stress phytohormones (e.g., jasmonic acid, salicylic acid, and ethylene) which are known to contribute to the induction of PCD. (iv) Generation of ESs accompanies K+ efflux from the cytoplasm that is also a mechanism of induction of PCD. Our review argues for the possibility of PCD induction by electrical signals and shows some directions of future investigations in the field.

Intrinsically Conductive Polymers for Striated Cardiac Muscle Repair.

One of the most important features of striated cardiac muscle is the excitability that turns on the excitation-contraction coupling cycle, resulting in the heart blood pumping function. The function of the heart pump may be impaired by events such as myocardial infarction, the consequence of coronary artery thrombosis due to blood clots or plaques. This results in the death of billions of cardiomyocytes, the formation of scar tissue, and consequently impaired contractility. A whole heart transplant remains the gold standard so far and the current pharmacological approaches tend to stop further myocardium deterioration, but this is not a long-term solution. Electrically conductive, scaffold-based cardiac tissue engineering provides a promising solution to repair the injured myocardium. The non-conductive component of the scaffold provides a biocompatible microenvironment to the cultured cells while the conductive component improves intercellular coupling as well as electrical signal propagation through the scar tissue when implanted at the infarcted site. The in vivo electrical coupling of the cells leads to a better regeneration of the infarcted myocardium, reducing arrhythmias, QRS/QT intervals, and scar size and promoting cardiac cell maturation. This review presents the emerging applications of intrinsically conductive polymers in cardiac tissue engineering to repair post-ischemic myocardial insult.

Variation of Electric Potential From The Stem of Leafy Plants Under Different Conditions.

Signals in leafy plants have been scientifically documented as hormonal or hydraulic in nature until some years ago whilst it was shown that different environmental stimuli additionally produce changes in electrical signals well observed especially in higher plants. These electrical signals employ ion channels to transmit signals within the plant. The transmission of these electrical signals causes physiological responses to biotic and abiotic stimuli. The mechanisms of electrical signal generation and transmission in leafy plants is correlated to the intensity and duration of stimuli, which shows that the real time detection of these electrical potentials will offer an approach to quantitatively relate plant reactions to environmental adjustments. However, the nature of electric potentials in leafy plants are not known, notwithstanding the fact that the knowledge may be useful in design of high efficient irrigation systems. In addition, due to the nature of these weak electrical signals, there might be other benefits than the physiological responses to stimuli. In this work, changes in electrical potentials due to abiotic changes in living plants have been determined. Electrical potentials changes under watering and lack of watering, in presence and absence of light conditions were carried out. Fluctuations of these electrical potentials were also investigated. The sample plant was obtained readily planted as a seedling from the nurseries. A measuring kit, which included electrodes and a voltmeter was used. One electrode was pierced through the lower trunk of the plant, a second one around the leaf area and was then connected to a voltage meter. The setups were placed in the Lab towards the sunlight and normal temperature environment. Experimental data was tabulated for four sessions of three hours throughout the day for a period of five days with enough water and five days without watering and graphical analysis was done which showed the electrical potentials variations. The different Electric Potentials were then plotted in graphs.

Discrete nonlocal N-fold Darboux transformation and soliton solutions in a reverse space-time nonlocal nonlinear self-dual network equation

In this paper, we construct a discrete nonlocal integrable lattice hierarchy related to a reverse space-time nonlocal nonlinear self-dual network equation which may have the potential applications in designing nonlocal electrical circuits and understanding the propagation of electrical signals. By means of nonlocal version of [Formula: see text]-fold Darboux transformation (DT) technique, discrete multi-soliton solutions in determinant form are constructed for the reverse space-time nonlocal nonlinear self-dual network equation. Through the asymptotic and graphic analysis, unstable soliton structures of one-, two- and three-soliton solutions are discussed graphically. We observe that the single components in this nonlocal equation display instability while the combined potential terms with nonlocal [Formula: see text]-symmetry show stable soliton structures. It is shown that these nonlocal solutions are clearly different from those of its corresponding local equation. The results given in this paper may explain the soliton propagation in electrical signals.

Discrete multi-soliton solutions and dynamics for a reverse-time nonlocal nonlinear self-dual network equation

Inspired by the idea of Ablowitz and Musslimani, a reverse-time nonlocal nonlinear self-dual network equation is proposed under certain nonlocal symmetry reduction. N-fold Darboux transformation technique is used to construct discrete unstable and stable multi-soliton solutions in zero seed background for this system. Based on the asymptotic and graphic analysis, structures of one-, two- and three-soliton solutions are shown graphically. It is found that the individual components in this nonlocal equation show unstable temporal soliton structures whereas the combined potential terms exhibit stable soliton structures. Dynamical behaviors for one-soliton solutions are investigated via numerical simulations. It is worth noting that the solutions of this nonlocal equation are clearly different from those of its corresponding local part. Results obtained in this paper may be helpful for the explanation of the propagation of electrical signals.

Java application for cytoskeleton filament characterization (JACFC).

JACFC is a Java web application (http://neuronanobiophysics.utsa.edu/) that provides both experts and non-experts in the field suitable tools for elucidating the molecular mechanisms modulating the electrical signal propagation, stability, and bundle formation of microtubules and actin filaments under different molecular (wild type, isoforms, mutants) and environmental (physiological and pathological) conditions. This acknowledgment might reveal the potential role of cytoskeleton filaments in neuronal activities, including molecular-level processing of information and neural regeneration. Molecular understanding of the polyelectrolyte properties of bionanowires, is also crucial for development of reliability, highly functioning small devices with biotechnological applications such as bionanosensors and computing bionanoprocessors.

Anisotropic conductive reduced graphene oxide/silk matrices promote post-infarction myocardial function by restoring electrical integrity

Myocardial infarction (MI) remains the leading cause of death globally, often leading to impaired cardiac function and pathological myocardial microenvironment. Electrical conduction abnormalities of the infarcted myocardium not only induce adverse myocardial remodeling but also prevent tissue repair. Restoring the myocardial electrical integrity, particularly the anisotropic electrical signal propagation within the injured area after infarction is crucial for an effective function recovery. Herein, optimized reduced graphene oxide (rGO) functionalized electrospun silk fibroin (rGO/silk) biomaterials presenting anisotropic conductivity and enhanced suturablity were developed and investigated as cardiac patches for their potential in improving the post-MI myocardial function of rat models. The results show that the anisotropic conductive rGO/silk patches exhibit remarkable therapeutic effect on repairing the infarcted myocardium compared to the nonconductive silk and isotropic conductive rGO/silk patches as determined by the enhanced pumping function, reduced susceptibility to arrhythmias, thickened left ventricular walls and improved survival of functional cardiomyocytes. Their notable effect on promoting the angiogenesis of capillaries in the infarcted myocardium has also been demonstrated. This study highlights an effective and biomimetic reconstruction of the electrical myocardial microenvironment based on the anisotropic conductive rGO/silk biomaterials as a promising option for promoting the repair of infarcted myocardium. Statement of significanceThe dysfunctional electrical microenvironment in the infarcted myocardium not only aggravates the adverse myocardial remodeling but also limits the effect of cardiac regenerative medicine. Although various conductive biomaterials have been employed to restore the electrical network in the infarcted myocardium in vivo, the anisotropic nature of the myocardial electrical microenvironment which enables directional electrical signal propagation were neglected. In this study, an anisotropic conductive rGO/silk biomaterial system is developed to improve the myocardial function post infarction by restoring the anisotropic electrical microenvironment in the infarcted myocardium. The promoted effects of anisotropic conductive grafts on repairing infarcted hearts are demonstrated with improved pumping function, cardiomyocyte survival, resistance to ventricular fibrillation, and angiogenesis of capillary network.

Scalable nanophotonic neural probes for multicolor and on-demand light delivery in brain tissue

Neural probes are in vivo brain-invasive devices that record and manipulate neural circuits using electricity, light, or drugs. The capability to shine distinct wavelengths and control their respective output locations for activation or deactivation of specific groups of neurons is desirable but remains unachieved. Here, we discuss our probe’s capability to deliver two independently controllable wavelengths (450 and 655 nm) in the location(s) of interest using nanophotonic directional couplers and ring resonators. These nanophotonics are scalable to dozens of outputs without significantly increasing the device’s lateral dimensions. Furthermore, they are entirely passive and thus do not require electrical input that results in heat generation. Besides, we integrate a high number of electrodes for a simultaneous neural activity readout. Thus, we overcome the challenges associated with multicolor illumination for neural devices by exploiting the capability of miniaturizable, passive probes to deliver two different frequencies in several areas of interest. These devices open the path towards investigating the in vivo electrical signal propagation under the individual or simultaneous activation or inhibition of distinct brain regions.

BCLA CLEAR – Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses.This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases.The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

Use of flicker noise in polyaniline to determine the product of mobility and lifetime of charge carriers

The current passing through a polyaniline layer generates electrical fluctuations, the amplitude of which increases in a part of the frequency spectrum with the inversion of the frequency f. It is deduced that this is due to the behavior of charge carriers trapped on energy levels in the bandgap. If these localized carriers are in equilibrium with the valence band, a frequency range can be found where the lifetime is inversely proportional to the frequency. Electron jumps between the levels and the valence band are manifested by the generation of electrical noise signals. The slope of the dependence of the noise current on 1/f was calculated, and the product of the mobility and lifetime of the holes was determined.

Modulational instability and dynamics of discrete rational soliton and mixed interaction solutions for a higher-order nonlinear self-dual network equation

In this paper, the higher-order nonlinear self-dual network equation is investigated. Firstly, an integrable lattice hierarchy associated with this equation is constructed from a discrete matrix spectral problem without the denominator. Secondly, the condition of modulational instability for this equation is given. Thirdly, the infinitely many conservation laws are constructed on the basis of its new Lax representation. Finally, the discrete generalised $$(m, N-m)$$ -fold Darboux transformation (DT) with non-zero constant as seed solution is used to derive new rational soliton (RS) and mixed interaction solutions. As an application, RS solutions can be obtained by the discrete generalised $$(1, N-1)$$ -fold DT (i.e., generalised $$(m, N-m)$$ -fold DT with $$m=1$$ ), and mixed interaction solutions of the usual sech-type soliton (US) and RS can be derived by the discrete generalised $$(2, N-2)$$ -fold DT (i.e., generalised $$(m, N-m)$$ -fold DT with $$m=2$$ ). We also perform the numerical simulations for such soliton solutions to explore their dynamical behaviours. Results given in this paper may have some prospective applications for understanding the propagation of electrical signals.

Exact solutions of non-linear Klein–Gordon equation with non-constant coefficients through the trial equation method

In this note, we use an extension of the trial equation method (also called the direct integral method) for partial differential equations with non-constant coefficients to derive exact solutions in the form of nonlinear waves. The model considered generalizes other classical models from physics like the Klein–Gordon equation, the $$(1 + 1)$$ -dimensional $$\phi ^4$$ -theory, the Fisher–Kolmogorov equation from population dynamics, and the Hodgkin–Huxley model which describes the propagation of electrical signals through the nervous system. As a particular example, the cylindrically symmetric cubic nonlinear Klein–Gordon equation is considered herein.

Remotely controlled self-powering electrical stimulators for osteogenic differentiation using bone inspired bioactive piezoelectric whitlockite nanoparticles

Endogenous electric fields naturally exist in our body and plays a vital role especially in the development and regeneration of bones. Therefore, piezoelectric bone implants are gaining ample attention due to its inherent electrical signal generation, but generally they lack bioactivity, resorption, and ECM like composition. To address this, we evoke ‘piezoelectricity’ in whitlockite (Ca 18 Mg 2 (HPO 4 ) 2 (PO 4 ) 12 ) nanoparticles (WH NPs) for the first time in literature. WH NPs are the second most-abundant inorganic bone mineral and reported for intermediate resorption compared to hydroxyapatite and tricalcium phosphate. Systematic electrical studies reveal that WH NPs annealed at 750 °C (PWH-750) exhibit superior ferroelectric and dielectric characteristics and produce electrical signals analogous to native tissues when triggered using FDA approved low-intensity pulsed ultrasound (LIPUS) noninvasively. The energy generation performance of Piezoelectric WH based self powered nanogenerators are analyzed and demonstrated to power the commercial LED upon LIPUS stimulation. The in vitro studies with pre-osteoblast MC3T3-E1 cells co-cultured with piezoelectric WH NPs exhibit increased ALP activity, calcium mineralization, and osteogenic gene expression along with significant upregulation of Piezo1, and TRPV4 expressions. This confirms the enhanced osteogenic differentiation compared to the control WH nanoparticles due to the remotely activated self powering capacity of piezoelectric WH NPs and thereby produce bioelectric signals analogous to native tissues. Thus, the study evidences the development of a potential bioactive piezoelectric ceramic with extensive applicability for future clinical translation. • Development of piezoelectric whitlockite nanoparticles for self-powered electrical cell stimulation. • The study also reports the development of the unique piezoelectric nanogenerator (PENG) based on biocompatible WH NPs. • LIPUS mediated electric field produced by the piezoelectric WH NPs promotes osteoblast proliferation and differentiation. • The study confirms the enhanced osteogenic differentiation via Piezo1 and TRPV4 mechanosensitive ion channels. • A new perspective in the field of regenerative medicine through self-powered electrical stimulation to cells.

Mathematically modeling action potentials in myelinated neurons to examine the role of myelin, ion channel density, and myelinated lengths on conduction

Since the seminal work of Hodgkin and Huxley, which quantitatively described the propagation of electrical signals through neurons, there has been much investigation into the electrical and geometrical properties of neurons and how they affect conduction velocity along a neuron’s length. To study human neuron behaviors, mathematical models have expanded upon Hodgkin and Huxley’s models to incorporate the effects of neurons that are myelinated by modeling myelinated portions of neurons as passive cables.Here, we present a developed mathematical model that discretizes a myelinated axon length and finely allows for control over a number of important electrical and geometrical properties. Using this model, we present and compare how myelin, inter-node length, and ion channel density affect conduction velocity in two different lengths of axons. We confirm that myelination, internode-length, and ion channel density correlate positively with conduction velocity, and propose potential mechanisms of this effect at lower node length and inter-node length values.

Structural Studies of the Interaction Between the Paddle Motif from NaV1.5Div and the Sea Anemone Toxin Anthopleurin-A

Voltage gated sodium channels (VGSC) are membrane proteins that are important in the central and peripheral nervous systems and cardiac muscles among others. The main function of VGSC is in the propagation of electrical signals by depolarizing excitable cells. Numerous diseases have been linked to defects in VGSC including epilepsy, mental retardation, and several ailments that could lead to sudden cardiac death. Furthermore, these channels are one of the primary targets of toxins from venomous animals. These toxins have been used as an excellent probe to study the function of VGSC due to their specific and potent effect on VGSC. The sea anemone toxin anthopleurin-A (ApA) inhibits the fast inactivation of the cardiac channel NaV1.5 by binding to the S3b-S4a motif (paddle motif) on the voltage sensing domain (VSD) of DIV. Here we used NMR spectroscopy to determine the solution structures of NaV1.5 DIV paddle motif and of ApA toxin, both in DPC micelles. The structure of the paddle motif takes a helix-turn-helix motif that aligns well with the cryo-EM structure of the full channel. Through paramagnetic relaxation enhancement, we determined that the paddle motif is mainly interacting with the interface region of the micelle. Based on 15N NMR relaxation studies, the paddle motif is mostly rigid with some residues at and around the loop in addition to the C-terminus undergoing ps-ns motion. NMR titration experiments between a 15N labeled paddle motif with unlabeled ApA toxin uncovered specific residues on the paddle that likely interact with the toxin. Further electrophysiology studies are needed to confirm the importance of these residues in toxin binding. We are in the process of determining the three-dimensional structure of the toxin-paddle complex in micelle.

Electrical Signal Propagation in Four Probes System Measuring at The Range of 20Hz - 600Hz

The electrical-supply on the earth’s surface are propagate from the positive electrode to the negative electrode. The electrons flow from the negative electrode to the positive electrode. In the conductor wire, an electric current tends to pass through the wire shell. The charge density decreases in proportion to the depth, the increase in frequency, and the material permeability. Based on these factors, practically, the conductor surface is often extended by making fibbers. If one of the trajectories on the earth gives an electric voltage, then the earth is not a perfect conductor, the earth as a large object with a surface is predicted to be relatively difficult to deliver an alternating electric current. Based on the previous statement, the granting of an electric current, and will more difficult to flow when the frequency is increased. The aim of this research is to find out the phenomena of earth resistance in the range of 20Hz-600Hz. It is expected that this data are useful for determining the frequency of effective exploration or also as a consideration when interpreting data. The study is conducted by giving an electric field to two electrodes with a measured current. Two electrodes are plugged into the ground for injecting current, and two others electrodes to pick up voltage which was reached. The measurements were made with an oscilloscope. The frequency was varied while recording the current that flow. The current flowed from the square wave current source that could be varied from 20Hz to 600Hz. From this experiment, it is found that the voltage decreases relatives along with the increase in the frequency.