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Nodes of ranvier

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https://www.readbyqxmd.com/read/27902705/neuronal-ndrg4-is-essential-for-nodes-of-ranvier-organization-in-zebrafish
#1
Laura Fontenas, Flavia De Santis, Vincenzo Di Donato, Cindy Degerny, Béatrice Chambraud, Filippo Del Bene, Marcel Tawk
Axon ensheathment by specialized glial cells is an important process for fast propagation of action potentials. The rapid electrical conduction along myelinated axons is mainly due to its saltatory nature characterized by the accumulation of ion channels at the nodes of Ranvier. However, how these ion channels are transported and anchored along axons is not fully understood. We have identified N-myc downstream-regulated gene 4, ndrg4, as a novel factor that regulates sodium channel clustering in zebrafish. Analysis of chimeric larvae indicates that ndrg4 functions autonomously within neurons for sodium channel clustering at the nodes...
November 2016: PLoS Genetics
https://www.readbyqxmd.com/read/27889898/the-transcription-factors-ebf1-and-ebf2-are-positive-regulators-of-myelination-in-schwann-cells
#2
Diego Moruzzo, Lucilla Nobbio, Bruno Sterlini, G Giacomo Consalez, Fabio Benfenati, Angelo Schenone, Anna Corradi
Myelin formation by Schwann cells is tightly controlled by multiple pathways and regulatory molecules. The Ebf2 gene, belonging to the Ebf family of transcription factors regulating cell development and differentiation, is expressed in Schwann cells, and Ebf2 knockout mice show peripheral nerve defects. We also found that Ebf1 is expressed in Schwann cells. To investigate Ebf function in myelination, we silenced Ebf genes in myelinating dorsal root ganglia cultures. Combined downregulation of Ebf genes leads to a severe impairment of myelin formation that is completely rescued by their specific overexpression, suggesting that the expression level of Ebf genes strongly influences axon myelination...
November 26, 2016: Molecular Neurobiology
https://www.readbyqxmd.com/read/27866733/review-of-the-literature-articles-published-in-the-last-five-years-that-have-changed-my-daily-practice
#3
REVIEW
E Delmont
Over the last five years, the management of peripheral neuropathies has become structured by the publication of recognized diagnostic criteria for inflammatory neuropathies and the elaboration of a function score, the R-ODS, used to evaluate the progression of these neuropathies. The concept of nodo-paranodopathy has enriched the concept of peripheral neuropathies, over-riding the classical mechanisms of axonal and demyelinating mechanisms. The structures of the nodes of Ranvier, gangliosides, contractin and neurofascin are preferential targets for auto-antibodies responsible for dysimmune neuropathies...
November 17, 2016: Revue Neurologique
https://www.readbyqxmd.com/read/27857121/guillain-barr%C3%A3-syndrome-a-century-of-progress
#4
REVIEW
John A Goodfellow, Hugh J Willison
In 1916, Guillain, Barré and Strohl reported on two cases of acute flaccid paralysis with high cerebrospinal fluid protein levels and normal cell counts - novel findings that identified the disease we now know as Guillain-Barré syndrome (GBS). 100 years on, we have made great progress with the clinical and pathological characterization of GBS. Early clinicopathological and animal studies indicated that GBS was an immune-mediated demyelinating disorder, and that severe GBS could result in secondary axonal injury; the current treatments of plasma exchange and intravenous immunoglobulin, which were developed in the 1980s, are based on this premise...
November 18, 2016: Nature Reviews. Neurology
https://www.readbyqxmd.com/read/27832602/activity-dependent-formation-and-location-of-voltage-gated-sodium-channel-clusters-at-a-cns-nerve-terminal-during-postnatal-development
#5
Jie Xu, Emmanuelle Berret, Jun Hee Kim
In auditory pathways, the precision of action potential (AP) propagation depends on axon myelination and high densities of voltage-gated Na (Nav) channels clustered at nodes of Ranvier. Changes in Nav channel expression at the heminode, the final node before the nerve terminal, can alter AP invasion into the presynaptic terminal. Here, we studied the activity-dependent formation of Nav channel clusters before and after hearing onset at P12 in the rat and mouse auditory brainstem. In rats, the Nav channel cluster at the heminode formed progressively during the second postnatal week, around hearing onset, whereas the Nav channel cluster at the nodes was present before hearing onset...
November 9, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27818385/contactin-associated-protein-1-cntnap1-mutations-induce-characteristic-lesions-of-the-paranodal-region
#6
Jean-Michel Vallat, Mathilde Nizon, Alex Magee, Bertrand Isidor, Laurent Magy, Yann Péréon, Laurence Richard, Robert Ouvrier, Benjamin Cogné, Jérôme Devaux, Stephan Zuchner, Stéphane Mathis
Congenital hypomyelinating neuropathy is a rare neonatal syndrome responsible for hypotonia and weakness. Nerve microscopic examination shows amyelination or hypomyelination. Recently, mutations in CNTNAP1 have been described in a few patients. CNTNAP1 encodes contactin-associated protein 1 (caspr-1), which is an essential component of the paranodal junctions of the peripheral and central nervous systems, and is necessary for the establishment of transverse bands that stabilize paranodal axo-glial junctions...
November 6, 2016: Journal of Neuropathology and Experimental Neurology
https://www.readbyqxmd.com/read/27771530/thrombin-and-protein-c-pathway-in-peripheral-nerve-schwann-cells
#7
Orna Gera, Efrat Shavit-Stein, Doron Bushi, Sagi Harnof, Marina Ben Shimon, Ronen Weiss, Valery Golderman, Amir Dori, Nicola Maggio, Kate Finegold, Joab Chapman
Thrombin and activated protein C (aPC) bound to the endothelial protein C receptor (EPCR) both activate protease-activated receptor 1 (PAR1) generating either harmful or protective signaling respectively. In the present study we examined the localization of PAR-1 and EPCR and thrombin activity in Schwann glial cells of normal and crushed peripheral nerve and in Schwannoma cell lines. In the sciatic crush model nerves were excised 1h, 1, 4, and 7days after the injury. Schwannoma cell lines produced high levels of prothrombin which is converted to active thrombin and expressed both EPCR and PAR-1 which co-localized...
December 17, 2016: Neuroscience
https://www.readbyqxmd.com/read/27717670/formation-and-disruption-of-functional-domains-in-myelinated-cns-axons
#8
Ryan B Griggs, Leonid M Yermakov, Keiichiro Susuki
Communication in the central nervous system (CNS) occurs through initiation and propagation of action potentials at excitable domains along axons. Action potentials generated at the axon initial segment (AIS) are regenerated at nodes of Ranvier through the process of saltatory conduction. Proper formation and maintenance of the molecular structure at the AIS and nodes are required for sustaining conduction fidelity. In myelinated CNS axons, paranodal junctions between the axolemma and myelinating oligodendrocytes delineate nodes of Ranvier and regulate the distribution and localization of specialized functional elements, such as voltage-gated sodium channels and mitochondria...
October 4, 2016: Neuroscience Research
https://www.readbyqxmd.com/read/27666389/fhf-independent-conduction-of-action-potentials-along-the-leak-resistant-cerebellar-granule-cell-axon
#9
Katarzyna Dover, Christopher Marra, Sergio Solinas, Marko Popovic, Sathyaa Subramaniyam, Dejan Zecevic, Egidio D'Angelo, Mitchell Goldfarb
Neurons in vertebrate central nervous systems initiate and conduct sodium action potentials in distinct subcellular compartments that differ architecturally and electrically. Here, we report several unanticipated passive and active properties of the cerebellar granule cell's unmyelinated axon. Whereas spike initiation at the axon initial segment relies on sodium channel (Nav)-associated fibroblast growth factor homologous factor (FHF) proteins to delay Nav inactivation, distal axonal Navs show little FHF association or FHF requirement for high-frequency transmission, velocity and waveforms of conducting action potentials...
September 26, 2016: Nature Communications
https://www.readbyqxmd.com/read/27616481/mutations-in-gldn-encoding-gliomedin-a-critical-component-of-the-nodes-of-ranvier-are-responsible-for-lethal-arthrogryposis
#10
Jérôme Maluenda, Constance Manso, Loic Quevarec, Alexandre Vivanti, Florent Marguet, Marie Gonzales, Fabien Guimiot, Florence Petit, Annick Toutain, Sandra Whalen, Romulus Grigorescu, Anne Dieux Coeslier, Marta Gut, Ivo Gut, Annie Laquerrière, Jérôme Devaux, Judith Melki
Arthrogryposis multiplex congenita (AMC) is a developmental condition characterized by multiple joint contractures resulting from reduced or absent fetal movements. Through linkage analysis, homozygosity mapping, and exome sequencing in four unrelated families affected by lethal AMC, we identified biallelic mutations in GLDN in the affected individuals. GLDN encodes gliomedin, a secreted cell adhesion molecule involved in the formation of the nodes of Ranvier. Transmission electron microscopy of the sciatic nerve from one of the affected individuals showed a marked lengthening defect of the nodes...
October 6, 2016: American Journal of Human Genetics
https://www.readbyqxmd.com/read/27615452/decrease-in-newly-generated-oligodendrocytes-leads-to-motor-dysfunctions-and-changed-myelin-structures-that-can-be-rescued-by-transplanted-cells
#11
Sarah Schneider, Agnès Gruart, Sofia Grade, Yina Zhang, Stephan Kröger, Frank Kirchhoff, Gregor Eichele, José M Delgado García, Leda Dimou
NG2-glia in the adult brain are known to proliferate and differentiate into mature and myelinating oligodendrocytes throughout lifetime. However, the role of these newly generated oligodendrocytes in the adult brain still remains little understood. Here we took advantage of the Sox10-iCreER(T2) x CAG-eGFP x Esco2(fl/fl) mouse line in which we can specifically ablate proliferating NG2-glia in adult animals. Surprisingly, we observed that the generation of new oligodendrocytes in the adult brain was severely affected, although the number of NG2-glia remained stable due to the enhanced proliferation of non-recombined cells...
September 12, 2016: Glia
https://www.readbyqxmd.com/read/27614087/preferential-conduction-block-of-myelinated-axons-by-nitric-oxide
#12
Peter Shrager, Margaret Youngman
Conduction block by nitric oxide (NO) was examined in myelinated and unmyelinated axons from both the central nervous system and peripheral nervous system. In rat vagus nerves, mouse optic nerves at P12-P23, adult and developing mouse sciatic nerves, and mouse spinal cords, myelinated fibers were preferentially blocked reversibly by concentrations of NO similar to those encountered in inflammatory lesions. The possibility that these differences between myelinated and unmyelinated axons are due to the normal developmental substitution of Na(+) channel subtype Nav 1...
September 10, 2016: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/27581456/reassembly-of-excitable-domains-after-cns-axon-regeneration
#13
Miguel A Marin, Silmara de Lima, Hui-Ya Gilbert, Roman J Giger, Larry Benowitz, Matthew N Rasband
UNLABELLED: Action potential initiation and propagation in myelinated axons require ion channel clustering at axon initial segments (AIS) and nodes of Ranvier. Disruption of these domains after injury impairs nervous system function. Traditionally, injured CNS axons are considered refractory to regeneration, but some recent approaches challenge this view by showing robust long-distance regeneration. However, whether these approaches allow remyelination and promote the reestablishment of AIS and nodes of Ranvier is unknown...
August 31, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27575893/solid-lipid-nanoparticles-surface-modified-with-anti-contactin2-or-anti-neurofascin-for-brain-targeted-delivery-of-medicines
#14
Nargess Gandomi, Reyhaneh Varshochian, Fatemeh Atyabi, Mohammad Hossein Ghahremani, Mohammad Sharifzadeh, Mohsen Amini, Rassoul Dinarvand
Multiple sclerosis (MS) is a chronic central nervous system (CNS) inflammation. Efficient drug delivery to brain is however hampered by blood brain barrier (BBB). In order to have highly efficient and safe delivery of drugs to brain, solid lipid nanoparticles (SLNs) have indicated promising potentials as smart carriers that can pass the blood brain barrier and deliver therapeutic biomolecules to the brain. In this study pegylated SLNs surface modified with using anti-Contactin2 or anti-Neurofascin, two axo-glial-glycoprotein antigens located in node of Ranvier, were prepared...
August 30, 2016: Pharmaceutical Development and Technology
https://www.readbyqxmd.com/read/27562187/development-of-a-voltage-dependent-current-noise-algorithm-for-conductance-based-stochastic-modelling-of-auditory-nerve-fibres
#15
Werner Badenhorst, Tania Hanekom, Johan J Hanekom
This study presents the development of an alternative noise current term and novel voltage-dependent current noise algorithm for conductance-based stochastic auditory nerve fibre (ANF) models. ANFs are known to have significant variance in threshold stimulus which affects temporal characteristics such as latency. This variance is primarily caused by the stochastic behaviour or microscopic fluctuations of the node of Ranvier's voltage-dependent sodium channels of which the intensity is a function of membrane voltage...
August 25, 2016: Biological Cybernetics
https://www.readbyqxmd.com/read/27548674/improved-simulation-of-electrodiffusion-in-the-node-of-ranvier-by-mesh-adaptation
#16
Ibrahima Dione, Jean Deteix, Thomas Briffard, Eric Chamberland, Nicolas Doyon
In neural structures with complex geometries, numerical resolution of the Poisson-Nernst-Planck (PNP) equations is necessary to accurately model electrodiffusion. This formalism allows one to describe ionic concentrations and the electric field (even away from the membrane) with arbitrary spatial and temporal resolution which is impossible to achieve with models relying on cable theory. However, solving the PNP equations on complex geometries involves handling intricate numerical difficulties related either to the spatial discretization, temporal discretization or the resolution of the linearized systems, often requiring large computational resources which have limited the use of this approach...
2016: PloS One
https://www.readbyqxmd.com/read/27512022/nonreciprocal-mechanisms-in-up-and-downregulation-of-spinal-motoneuron-excitability-by-modulators-of-kcnq-kv7-channels
#17
Joseph Lombardo, Melissa A Harrington
KCNQ/Kv7 channels form a slow noninactivating K(+) current, also known as the M current. They activate in the subthreshold range of membrane potentials and regulate different aspects of excitability in neurons of the central nervous system. In spinal motoneurons (MNs), KCNQ/Kv7 channels have been identified in the somata, axonal initial segment, and nodes of Ranvier, where they generate a slow, noninactivating, K(+) current sensitive to both muscarinic receptor-mediated inhibition and KCNQ/Kv7 channel blockers...
November 1, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27478169/fractionation-spares-mice-from-radiation-induced-reductions-in-weight-gain-but-does-not-prevent-late-oligodendrocyte-lineage-side-effects
#18
Sage Begolly, Peter G Shrager, John A Olschowka, Jacqueline P Williams, M Kerry O'Banion
PURPOSE: To determine the late effects of fractionated versus single-dose cranial radiation on murine white matter. METHODS AND MATERIALS: Mice were exposed to 0 Gy, 6 × 6 Gy, or 1 × 20 Gy cranial irradiation at 10 to 12 weeks of age. Endpoints were assessed through 18 months from exposure using immunohistochemistry, electron microscopy, and electrophysiology. RESULTS: Weight gain was temporarily reduced after irradiation; greater loss was seen after single versus fractionated doses...
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/27463510/chronic-peripheral-nerve-compression-disrupts-paranodal-axoglial-junctions
#19
Yoshinori Otani, Leonid M Yermakov, Jeffrey L Dupree, Keiichiro Susuki
INTRODUCTION: Peripheral nerves are often exposed to mechanical stress leading to compression neuropathies. The pathophysiology underlying nerve dysfunction by chronic compression is largely unknown. METHODS: We analyzed molecular organization and fine structures at and near nodes of Ranvier in a compression neuropathy model in which a silastic tube was placed around the mouse sciatic nerve. RESULTS: Immunofluorescence study showed that clusters of cell adhesion complex forming paranodal axoglial junctions were dispersed with frequent overlap with juxtaparanodal components...
July 27, 2016: Muscle & Nerve
https://www.readbyqxmd.com/read/27457083/nerve-conduction-through-dendrites-via-proton-hopping
#20
Lemont B Kier
Our previous studies of the role of proton hopping in nerve conduction have dealt with the axon, soma, synapse, and nodes of Ranvier. We complete the study and application of the theory of proton hopping being the system of nerve conduction by examining the dendrites and their accompanying spines as they function within the nerve system. The role of proton hopping continues to be a very probable mechanism within this intermediate system linking two nerves at the synapse.
July 25, 2016: Current Computer-aided Drug Design
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