Search results for " Conduction"
showing 10 items of 373 documents
Analysis of Microstructure of the Cardiac Conduction System Based on Three-Dimensional Confocal Microscopy
2016
The specialised conducting tissues present in the ventricles are responsible for the fast distribution of the electrical impulse from the atrio-ventricular node to regions in the subendocardial myocardium. Characterisation of anatomical features of the specialised conducting tissues in the ventricles is highly challenging, in particular its most distal section, which is connected to the working myocardium via Purkinje-myocardial junctions. The goal of this work is to characterise the architecture of the distal section of the Purkinje network by differentiating Purkinje cells from surrounding tissue, performing a segmentation of Purkinje fibres at cellular scale, and mathematically describin…
Changes in the spatial distribution of the Purkinje network after acute myocardial infarction in the pig
2018
Purkinje cells (PCs) are more resistant to ischemia than myocardial cells, and are suspected to participate in ventricular arrhythmias following myocardial infarction (MI). Histological studies afford little evidence on the behavior and adaptation of PCs in the different stages of MI, especially in the chronic stage, and no quantitative data have been reported to date beyond subjective qualitative depictions. The present study uses a porcine model to present the first quantitative analysis of the distal cardiac conduction system and the first reported change in the spatial distribution of PCs in three representative stages of MI: an acute model both with and without reperfusion; a subacute …
Long-range vortex transfer in superconducting nanowires
2019
Under high-enough values of perpendicularly-applied magnetic feld and current, a type-II superconductor presents a fnite resistance caused by the vortex motion driven by the Lorentz force. To recover the dissipation-free conduction state, strategies for minimizing vortex motion have been intensely studied in the last decades. However, the non-local vortex motion, arising in areas depleted of current, has been scarcely investigated despite its potential application for logic devices. Here, we propose a route to transfer vortices carried by non-local motion through long distances (up to 10 micrometers) in 50nm-wide superconducting WC nanowires grown by Ga+ Focused Ion Beam Induced Deposition.…
A quantitative structural and morphometric analysis of the Purkinje network and the Purkinje-myocardial junctions in pig hearts
2017
The morpho-functional properties of the distal section of the cardiac Purkinje network (PN) and the Purkinje-myocardial junctions (PMJs) are fundamental to understanding the sequence of electrical activation in the heart. The overall structure of the system has already been described, and several computational models have been developed to gain insight into its involvement in cardiac arrhythmias or its interaction with implantable devices, such as pacemakers. However, anatomical descriptions of the PN in the literature have not enabled enough improvements in the accuracy of anatomical-based electrophysiological simulations of the PN in 3D hearts models. In this work, we study the global dis…
Cardiac electrical defects in progeroid mice and Hutchinson-Gilford progeria syndrome patients with nuclear lamina alterations
2016
This work was supported by Spanish Ministry of Economy and Competitiveness (MINECO) Grants SAF2010-16044 and SAF2013-46663-R (to V.A.), SAF2011-30312 and SAF2014-58286-C2-1-R (to L.H.-M.), SAF2011-30088 (to E.D.), and SAF2014-52413-R (to C.L.-O.) and Fondo de Investigación Sanitaria del Instituto de Salud Carlos III Grants RD12/0042/0028 (to V.A.), RD12/0042/0011 (to J.T.), and RD12/0042/0002 (to L.H.-M.), with cofunding from the Fondo Europeo de Desarrollo Regional and the Progeria Research Foundation. J.A.G. is the recipient of a U-Mobility Grant from the Marie Curie cofunding of Regional, National and International Programme (Grant 246550). The Instituto Universitario de Oncología is sup…
Septin/anillin filaments scaffold central nervous system myelin to accelerate nerve conduction
2016
Myelination of axons facilitates rapid impulse propagation in the nervous system. The axon/myelin-unit becomes impaired in myelin-related disorders and upon normal aging. However, the molecular cause of many pathological features, including the frequently observed myelin outfoldings, remained unknown. Using label-free quantitative proteomics, we find that the presence of myelin outfoldings correlates with a loss of cytoskeletal septins in myelin. Regulated by phosphatidylinositol-(4,5)-bisphosphate (PI(4,5)P2)-levels, myelin septins (SEPT2/SEPT4/SEPT7/SEPT8) and the PI(4,5)P2-adaptor anillin form previously unrecognized filaments that extend longitudinally along myelinated axons. By confoca…
Chronically elevated branched chain amino acid levels are pro-arrhythmic.
2022
Aim. Cardiac arrhythmias comprise a major health and economic burden and are associated with significant morbidity and mortality, including cardiac failure, stroke and sudden cardiac death (SCD). Development of efficient preventive and therapeutic strategies is hampered by incomplete knowledge of disease mechanisms and pathways. Our aim is to identify novel mechanisms underlying cardiac arrhythmia and SCD using an unbiased approach. Methods and Results. We employed a phenotype-driven N-ethyl-N-nitrosourea (ENU) mutagenesis screen and identified a mouse line with a high incidence of sudden death at young age (6-9 weeks) in the absence of prior symptoms. Affected mice were found to be homozyg…
Transient hypothyroidism during lactation alters the development of the corpus callosum in rats. An in vivo magnetic resonance image and electron mic…
2020
Magnetic resonance imaging (MRI) data of children with late diagnosed congenital hypothyroidism and cognitive alterations such as abnormal verbal memory processing suggest altered telencephalic commissural connections. The corpus callosum (CC) is the major inter-hemispheric commissure that contra-laterally connects neocortical areas. However, in late diagnosed neonates with congenital hypothyroidism, the possible effect of early transient and chronic postnatal hypothyroidism still remains unknown. We have studied the development of the anterior, middle and posterior CC, using in vivo MRI and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated r…
Histological and morphometric study of the components of the sinus and atrioventricular nodes in horses and dogs
2019
Abstract The cardiac nodes are the source of the electrical impulse that is transmitted to the heart, the aim of this work is study the histological and morphometric characteristics of the different components of the sinus and atrioventricular nodes in horses and dogs that help to know the physiopathology of these nodes. A group of ten horse hearts and five dog hearts were used. The region of the sinus and atrioventricular nodes was sectioned serially, and the block of tissue removed for study. The samples were assessed using a morphometric analysis with the Image-Pro Plus 7.1 software and the acquisition of the images using a Leica DMD108 optic microscope. The shape of the horse's sinus no…
Multisite field potential recordings and analysis of the impulse propagation pattern in cardiac cells culture
2007
To provide further insights into the impulse propagation between cardiac myocytes, we performed multiparametric studies of excitation spread with cellular resolution in confluent monolayers of cultured cardiomyocytes (CM). Simultaneous paired intracellular recordings of action potentials in two individual CM revealed slight periodic spontaneous advances/delays in the interspike time lag. Multisite field potential recordings performed with microelectrode arrays (MEA) confirmed random and iterative cycle-to-cycle changes in the direction of excitation spread. These local spontaneous variations in the cardiac impulse propagation pathways may be a safety process protecting against microscopical…