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Bryson M, Kloefkorn H, Idlett-Ali S, Carrasco DI, Noble DJ, Martin K, Sawchuk MA, Au Yong N, Garraway SM, Hochman S. Emergent epileptiform activity in spinal sensory circuits drives ectopic bursting in afferent axons and sensory dysfunction after cord injury. Pain 2024:00006396-990000000-00676. [PMID: 39106457 DOI: 10.1097/j.pain.0000000000003364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 06/25/2024] [Indexed: 08/09/2024]
Abstract
ABSTRACT Spinal cord injury leads to hyperexcitability and dysfunction in spinal sensory processing. As hyperexcitable circuits can become epileptiform, we explored whether such activity emerges in a thoracic spinal cord injury (SCI) contusion model of neuropathic pain. Recordings from spinal sensory axons in multiple below-lesion segmental dorsal roots demonstrated that SCI facilitated the emergence of spontaneous ectopic burst spiking in afferent axons, which were correlated across multiple adjacent dorsal roots. Burst frequency correlated with behavioral mechanosensitivity. The same bursting events were recruited by afferent stimulation, and timing interactions with ongoing spontaneous bursts revealed that recruitment was limited by a prolonged post-burst refractory period. Ectopic bursting in afferent axons was driven by GABAA receptor activation, presumably by conversion of subthreshold GABAergic interneuronal presynaptic axoaxonic inhibitory actions to suprathreshold spiking. Collectively, the emergence of stereotyped bursting circuitry with hypersynchrony, sensory input activation, post-burst refractory period, and reorganization of connectivity represent defining features of an epileptiform network. Indeed, these same features were reproduced in naive animals with the convulsant 4-aminopyridine (fampridine). We conclude that spinal cord injury promotes the emergence of epileptiform activity in spinal sensory networks that promote profound corruption of sensory signaling. This includes hyperexcitability and bursting by ectopic spiking in afferent axons that propagate bidirectionally by reentrant central and peripheral projections as well as sensory circuit hypoexcitability during the burst refractory period. More broadly, the work links circuit hyperexcitability to epileptiform circuit emergence, further strengthening it as a conceptual basis to understand features of sensory dysfunction and neuropathic pain.
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Affiliation(s)
- Matthew Bryson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Heidi Kloefkorn
- Department of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR, United States
| | | | - Dario I Carrasco
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States
| | - Donald James Noble
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Karmarcha Martin
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Michael A Sawchuk
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Nicholas Au Yong
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States
| | - Sandra M Garraway
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Shawn Hochman
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
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Rocca MA, Valsasina P, Lamanna MT, Colombo B, Martinelli V, Filippi M. Functional connectivity modifications in monoaminergic circuits occur in fatigued MS patients treated with fampridine and amantadine. J Neurol 2023; 270:4697-4706. [PMID: 37462753 DOI: 10.1007/s00415-023-11858-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 09/21/2023]
Abstract
BACKGROUND Monoaminergic network dysfunction may have a role in multiple sclerosis (MS) fatigue pathogenesis. OBJECTIVE To investigate modifications of fatigue severity and resting state (RS) functional connectivity (FC) in monoaminergic networks of 45 fatigued MS patients after different symptomatic treatments. METHODS Patients were randomly, blindly assigned to fampridine (n = 15), amantadine (n = 15) or placebo (n = 15) treatment and underwent clinical and 3T-MRI evaluations at baseline (t0) and week 4 (w4), i.e. after four weeks of treatment. Fifteen healthy controls (HC) were enrolled. Dopamine-, noradrenaline- and serotonin-related RS FC was assessed by PET-guided constrained independent component analysis. RESULTS At t0, MS patients showed widespread monoamine-related RS FC abnormalities. At w4, fatigue scores decreased in all groups (p = range < 0.001-0.002). Concomitantly, fampridine and amantadine patients showed increased insular RS FC in dopamine-related and noradrenaline-related networks (p < 0.001, uncorrected). Amantadine patients also showed increased RS FC of anterior cingulate cortex in dopamine-related and noradrenaline-related networks (p < 0.001, uncorrected). Placebo patients showed increased precuneus/middle cingulate RS FC in the noradrenaline-related network (p < 0.001, uncorrected). In fampridine and placebo patients, just tendencies towards correlations between RS FC and fatigue modifications were found. CONCLUSIONS In MS patients, specific RS FC modifications in PET-guided monoaminergic networks were observed, concomitantly with fatigue improvements following treatment. TRIAL REGISTRATION NUMBER EudraCT 2010-023678-38.
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Affiliation(s)
- Maria A Rocca
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.
- Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
- Vita-Salute San Raffaele University, Milan, Italy.
| | - Paola Valsasina
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Teresa Lamanna
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Bruno Colombo
- Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Massimo Filippi
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Neurorehabilitation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Neurophysiology Service, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
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Bryson M, Kloefkorn H, Idlett-Ali S, Martin K, Garraway SM, Hochman S. Emergent epileptiform activity drives spinal sensory circuits to generate ectopic bursting in intraspinal afferent axons after cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.03.547522. [PMID: 37461440 PMCID: PMC10349934 DOI: 10.1101/2023.07.03.547522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/14/2024]
Abstract
Spinal cord injury ( SCI ) leads to hyperexcitability and dysfunction in spinal sensory processing. As hyperexcitable circuits can become epileptiform elsewhere, we explored whether such activity emerges in spinal sensory circuits in a thoracic SCI contusion model of neuropathic pain. Recordings from spinal sensory axons in multiple below-lesion segmental dorsal roots ( DRs ) demonstrated that SCI facilitated the emergence of spontaneous ectopic burst spiking in afferent axons, which synchronized across multiple adjacent DRs. Burst frequency correlated with behavioral mechanosensitivity. The same bursting events were recruited by afferent stimulation, and timing interactions with ongoing spontaneous bursts revealed that recruitment was limited by a prolonged post-burst refractory period. Ectopic bursting in afferent axons was driven by GABA A receptor activation, presumably via shifting subthreshold GABAergic interneuronal presynaptic axoaxonic inhibitory actions to suprathreshold spiking. Collectively, the emergence of stereotyped bursting circuitry with hypersynchrony, sensory input activation, post-burst refractory period, and reorganization of connectivity represent defining features of epileptiform networks. Indeed, these same features were reproduced in naïve animals with the convulsant 4-aminopyridine ( 4-AP ). We conclude that SCI promotes the emergence of epileptiform activity in spinal sensory networks that promotes profound corruption of sensory signaling. This corruption includes downstream actions driven by ectopic afferent bursts that propagate via reentrant central and peripheral projections and GABAergic presynaptic circuit hypoexcitability during the refractory period.
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Paredes-Cruz M, Grijalva I, Martínez-López YE, Guizar-Sahagún G, Colín-Ramírez E, Rojano-Mejía D. Functional improvement in individuals with chronic spinal cord injury treated with 4-aminopyridine: A systematic review. Front Neurol 2022; 13:1034730. [DOI: 10.3389/fneur.2022.1034730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/11/2022] [Indexed: 11/30/2022] Open
Abstract
Study designSystematic review.ObjectiveTo provide current evidence on the efficacy of 4-aminopyridine (4-AP) to bring about functional improvement in individuals with chronic traumatic spinal cord injury (SCI).MethodsThe Medline (PubMed), Web of Science and SCOPUS databases were systematically searched for relevant articles on the efficacy of 4-AP to treat SCI, from the dates such articles were first published until May 2022. Full-text versions of all the articles selected were examined independently by two reviewers. Methodological quality was rated using the Modified Jadad Scale, and risk of bias was assessed with the RoB-2 test. Data extracted included human models/types, PRISMA assessment protocols, and the results of each study. Descriptive syntheses are provided.ResultsIn total, 28 articles were initially identified, 10 of which were included after screening. Most of the studies reviewed reported some degree of patient improvement in one or more of the following parameters: motor, sensitivity and sexual function, sphincter control, spasticity, ability to function independently, quality of life, central motor conduction, pain, and pulmonary function.ConclusionsThis review confirms the efficacy of 4-AP in improving several conditions resulting from SCI but further research on this topic is warranted. Additional randomized clinical trials with 4-AP involving larger sample sizes are needed, as are consistent outcome measures in order to obtain adequate data for analysis with a view to enhance treatment benefits.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=334835, PROSPERO CRD42022334835.
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Radomski KL, Zi X, Lischka FW, Noble MD, Galdzicki Z, Armstrong RC. Acute axon damage and demyelination are mitigated by 4-aminopyridine (4-AP) therapy after experimental traumatic brain injury. Acta Neuropathol Commun 2022; 10:67. [PMID: 35501931 PMCID: PMC9059462 DOI: 10.1186/s40478-022-01366-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/11/2022] [Indexed: 11/10/2022] Open
Abstract
Damage to long axons in white matter tracts is a major pathology in closed head traumatic brain injury (TBI). Acute TBI treatments are needed that protect against axon damage and promote recovery of axon function to prevent long term symptoms and neurodegeneration. Our prior characterization of axon damage and demyelination after TBI led us to examine repurposing of 4-aminopyridine (4-AP), an FDA-approved inhibitor of voltage-gated potassium (Kv) channels. 4-AP is currently indicated to provide symptomatic relief for patients with chronic stage multiple sclerosis, which involves axon damage and demyelination. We tested clinically relevant dosage of 4-AP as an acute treatment for experimental TBI and found multiple benefits in corpus callosum axons. This randomized, controlled pre-clinical study focused on the first week after TBI, when axons are particularly vulnerable. 4-AP treatment initiated one day post-injury dramatically reduced axon damage detected by intra-axonal fluorescence accumulations in Thy1-YFP mice of both sexes. Detailed electron microscopy in C57BL/6 mice showed that 4-AP reduced pathological features of mitochondrial swelling, cytoskeletal disruption, and demyelination at 7 days post-injury. Furthermore, 4-AP improved the molecular organization of axon nodal regions by restoring disrupted paranode domains and reducing Kv1.2 channel dispersion. 4-AP treatment did not resolve deficits in action potential conduction across the corpus callosum, based on ex vivo electrophysiological recordings at 7 days post-TBI. Thus, this first study of 4-AP effects on axon damage in the acute period demonstrates a significant decrease in multiple pathological hallmarks of axon damage after experimental TBI.
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Affiliation(s)
- Kryslaine L. Radomski
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Xiaomei Zi
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Fritz W. Lischka
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Mark D. Noble
- Department of Biomedical Genetics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Box 633, Rochester, NY 14642 USA
| | - Zygmunt Galdzicki
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Regina C. Armstrong
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
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Hamad MN, Boroda N, Echenique DB, Dieter RA, Amirouche FML, Gonzalez MH, Kerns JM. Compound Motor Action Potentials During a Modest Nerve Crush. Front Cell Neurosci 2022; 16:798203. [PMID: 35431816 PMCID: PMC9005805 DOI: 10.3389/fncel.2022.798203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 03/03/2022] [Indexed: 11/18/2022] Open
Abstract
Nerve crush injury results in axonotmesis, characterized by disruption of axons and their myelin sheaths with relative sparing of the nerve’s connective tissue. Despite the widespread use of crush injury models, no standardized method for producing these lesions has been established. We characterize a crush model in which a narrow forceps is used to induce a modest and controlled compressive injury. The instantaneous compound motor action potential (CMAP) is monitored in situ and in real-time, allowing the characterization of neuromuscular response during and after injury. The tibial nerves of 11 anesthetized rats were surgically isolated. After the placement of electrodes, CMAPs were elicited and registered using a modular-data-acquisition system. Dumont-#5 micro-forceps were instrumented with a force transducer allowing force measurement via a digital sensor. Baseline CMAPs were recorded prior to crush and continued for the duration of the experiment. Nerve crushing commenced by gradually increasing the force applied to the forceps. At a target decrease in CMAP amplitude of 70%–90%, crushing was halted. CMAPs were continually recorded for 5–20 min after the termination of the crushing event. Nerves were then fixed for histological assessment. The following post-crush mean values from 19 trials were reported: peak CMAP amplitude decreased by 81.6% from baseline, duration of crush was 17 sec, rate of applied force was 0.03 N/sec, and maximal applied force was 0.5 N. A variety of agonal phenomena were evident post-lesion. Following the initial decrease in CMAP, 8 of 19 trials demonstrated a partial and transient recovery, followed by a further decline. Thirteen trials exhibited a CMAP amplitude near zero at the end of the recording. Twelve trials demonstrated a superimposed EMG background response during and after the crush event, with disappearance occurring within 4–8 min. Qualitative histology assessment at the lesion site demonstrated a correspondence between CMAP response and partial sparing of nerve fibers. By using a targeted decline in CMAP amplitude as the endpoint, researchers may be able to produce controlled, brief, and reproducible crush injuries. This model can also be used to test interventions aimed at enhancing subsequent regeneration and behavioral recovery.
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Affiliation(s)
- Mohammed Nazmy Hamad
- Department of Orthopedic Surgery, University of Illinois Chicago, Chicago, IL, United States
| | - Nickolas Boroda
- Department of Orthopedic Surgery, University of Illinois Chicago, Chicago, IL, United States
| | | | - Raymond A. Dieter
- Hines Veterans Affairs Hospital Research Service, Hines, IL, United States
| | - Farid M. L. Amirouche
- Department of Orthopedic Surgery, University of Illinois Chicago, Chicago, IL, United States
| | - Mark H. Gonzalez
- Department of Orthopedic Surgery, University of Illinois Chicago, Chicago, IL, United States
| | - James M. Kerns
- Department of Orthopedic Surgery, University of Illinois Chicago, Chicago, IL, United States
- *Correspondence: James M. Kerns
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Malamud E, Otallah SI. Use of Dalfampridine in a Young Child with Episodic Ataxia Type 2. Child Neurol Open 2022; 9:2329048X221075447. [PMID: 35127965 PMCID: PMC8811424 DOI: 10.1177/2329048x221075447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/03/2021] [Accepted: 01/06/2022] [Indexed: 11/16/2022] Open
Abstract
Episodic ataxia type 2 (EA2) is a rare autosomal dominant disorder associated with mutations of the CACNA1A gene. 1 Because there is no curative therapy available, EA2 is typically managed symptomatically. First line treatment has typically been with acetazolamide. 2 Dalfampridine has also been noted to decrease the frequency and duration of ataxic attacks in patients ranging in age from adolescence through adulthood. 3 , 4 The efficacy and dosing of dalfampridine has not yet been studied in younger pediatric populations. The lack of published experience in younger children can and has led to these patients going without potentially safe and effective treatment. Thus, we describe an 8-year-old girl with EA2 and a confirmed CACNA1A gene mutation whose symptoms had been previously unrelieved by acetazolamide. She was subsequently trialed on dalfampridine and experienced symptomatic relief at a dose of 0.3 mg/kg.
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Affiliation(s)
| | - Scott I. Otallah
- Division of Pediatric Neurology, Department of Neurology, Atrium Health Wake Forest Baptist, Medical Center Boulevard, JT9, Winston-Salem, NC
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Jankowska E, Hammar I. The plasticity of nerve fibers: the prolonged effects of polarization of afferent fibers. J Neurophysiol 2021; 126:1568-1591. [PMID: 34525323 DOI: 10.1152/jn.00718.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The review surveys various aspects of the plasticity of nerve fibers, in particular the prolonged increase in their excitability evoked by polarization, focusing on a long-lasting increase in the excitability of myelinated afferent fibers traversing the dorsal columns of the spinal cord. We review the evidence that increased axonal excitability 1) follows epidurally applied direct current (DC) as well as relatively short (5 or 10 ms) current pulses and synaptically evoked intrinsic field potentials; 2) critically depends on the polarization of branching regions of afferent fibers at the sites where they bifurcate and give off axon collaterals entering the spinal gray matter in conjunction with actions of extrasynaptic GABAA membrane receptors; and 3) shares the feature of being activity-independent with the short-lasting effects of polarization of peripheral nerve fibers. A comparison between the polarization evoked sustained increase in the excitability of dorsal column fibers and spinal motoneurons (plateau potentials) indicates the possibility that they are mediated by partly similar membrane channels (including noninactivating type L Cav++ 1.3 but not Na+ channels) and partly different mechanisms. We finally consider under which conditions transspinally applied DC (tsDCS) might reproduce the effects of epidural polarization on dorsal column fibers and the possible advantages of increased excitability of afferent fibers for the rehabilitation of motor and sensory functions after spinal cord injuries.NEW & NOTEWORTHY This review supplements previous reviews of properties of nerve fibers by surveying recent experimental evidence for their long-term plasticity. It also extends recent descriptions of spinal effects of DC by reviewing effects of polarization of afferent nerve fibers within the dorsal columns, the mechanisms most likely underlying the long-lasting increase in their excitability and possible clinical implications.
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Affiliation(s)
- Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ingela Hammar
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Martins Â, Gouveia D, Cardoso A, Carvalho C, Coelho T, Silva C, Viegas I, Gamboa Ó, Ferreira A. A Controlled Clinical Study of Intensive Neurorehabilitation in Post-Surgical Dogs with Severe Acute Intervertebral Disc Extrusion. Animals (Basel) 2021; 11:ani11113034. [PMID: 34827767 PMCID: PMC8614363 DOI: 10.3390/ani11113034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/16/2021] [Accepted: 10/20/2021] [Indexed: 12/15/2022] Open
Abstract
Simple Summary This study explores the potential intensive neurorehabilitation plasticity effects in post-surgical paraplegic dogs with severe acute intervertebral disc extrusion aiming to achieve ambulatory status. The intensive neurorehabilitation protocol translated in 99.4% (167/168) of recovery in deep pain perception-positive dogs and 58.5% (55/94) in deep pain perception-negative dogs. There was 37.3% (22/59) spinal reflex locomotion, obtained within a maximum period of 3 months. Thus, intensive neurorehabilitation may be a useful approach for this population of dogs, avoiding future euthanasia and promoting an estimated time window of 3 months to recover. Abstract This retrospective controlled clinical study aimed to verify if intensive neurorehabilitation (INR) could improve ambulation faster than spontaneous recovery or conventional physiotherapy and provide a possible therapeutic approach in post-surgical paraplegic deep pain perception-positive (DPP+) (with absent/decreased flexor reflex) and DPP-negative (DDP−) dogs, with acute intervertebral disc extrusion. A large cohort of T10-L3 Spinal Cord Injury (SCI) dogs (n = 367) were divided into a study group (SG) (n = 262) and a control group (CG) (n = 105). The SG was based on prospective clinical cases, and the CG was created by retrospective medical records. All SG dogs performed an INR protocol by the hospitalization regime based on locomotor training, electrical stimulation, and, for DPP−, a combination with pharmacological management. All were monitored throughout the process, and measuring the outcome for DPP+ was performed by OFS and, for the DPP−, by the new Functional Neurorehabilitation Scale (FNRS-DPP−). In the SG, DPP+ dogs had an ambulation rate of 99.4% (n = 167) and, in DPP−, of 58.5% (n = 55). Moreover, in DPP+, there was a strong statistically significant difference between groups regarding ambulation (p < 0.001). The same significant difference was verified in the DPP– dogs (p = 0.007). Furthermore, a tendency toward a significant statistical difference (p = 0.058) regarding DPP recovery was demonstrated between groups. Of the 59 dogs that did not recover DPP, 22 dogs achieved spinal reflex locomotion (SRL), 37.2% within a maximum of 3 months. The progressive myelomalacia cases were 14.9% (14/94). Therefore, although it is difficult to assess the contribution of INR for recovery, the results suggested that ambulation success may be improved, mainly regarding time.
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Affiliation(s)
- Ângela Martins
- Faculty of Veterinary Medicine, Lusófona University, Campo Grande, 1300-477 Lisboa, Portugal
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
- CIISA—Centro Interdisciplinar-Investigação em Saúde Animal, Faculdade de Medicina Veterinária, Av. Universidade Técnica de Lisboa, 1300-477 Lisboa, Portugal;
- Superior School of Health, Protection and Animal Welfare, Polytechnic Institute of Lusophony, Campo Grande, 1300-477 Lisboa, Portugal
- Correspondence:
| | - Débora Gouveia
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
- Superior School of Health, Protection and Animal Welfare, Polytechnic Institute of Lusophony, Campo Grande, 1300-477 Lisboa, Portugal
| | - Ana Cardoso
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
| | - Carla Carvalho
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
| | - Tiago Coelho
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
| | - Cátia Silva
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
| | - Inês Viegas
- Animal Rehabilitation Center, Arrábida Veterinary Hospital, Azeitão, 2925-583 Setúbal, Portugal; (D.G.); (A.C.); (C.C.); (T.C.); (C.S.); (I.V.)
| | - Óscar Gamboa
- Faculty of Veterinary Medicine, University of Lisbon, 1300-477 Lisboa, Portugal;
| | - António Ferreira
- CIISA—Centro Interdisciplinar-Investigação em Saúde Animal, Faculdade de Medicina Veterinária, Av. Universidade Técnica de Lisboa, 1300-477 Lisboa, Portugal;
- Faculty of Veterinary Medicine, University of Lisbon, 1300-477 Lisboa, Portugal;
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Rocca MA, Valsasina P, Colombo B, Martinelli V, Filippi M. Cortico-subcortical functional connectivity modifications in fatigued multiple sclerosis patients treated with fampridine and amantadine. Eur J Neurol 2021; 28:2249-2258. [PMID: 33852752 DOI: 10.1111/ene.14867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/07/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND AND PURPOSE Fatigue in multiple sclerosis (MS) is common and disabling; medication efficacy is still not fully proven. The aim of this study was to investigate 4-week modifications of fatigue severity in 45 relapsing-remitting MS patients after different symptomatic treatments, and changes in concomitant resting state (RS) functional connectivity (FC). METHODS Patients were randomly, blindly assigned to treatment with fampridine (n = 15), amantadine (n = 15) or placebo (n = 15), and underwent clinical assessment and 3-Tesla RS functional magnetic resonance imaging at baseline (t0) and after 4 weeks (w4) of treatment. Fifteen healthy controls (HCs) were also studied. Changes in modified fatigue impact scale (MFIS) score and network RS FC were assessed. RESULTS In MS, abnormalities of network RS FC at t0 did not differ between treatment groups and correlated with fatigue severity. At w4, global scores and subscores on the MFIS decreased in all groups, with no time-by-treatment interaction. At w4, all patient groups had changes in RS FC in several networks, with significant time-by-treatment interactions in basal ganglia, sensorimotor and default-mode networks in fampridine-treated patients versus the other groups, and in frontoparietal network in amantadine-treated patients. In the fampridine group, RS FC changes correlated with concurrently decreased MFIS score (r range = -0.75 to 0.74, p range = 0.003-0.05). CONCLUSIONS Fatigue improved in all MS groups, independently of treatment. Concomitant RS FC modifications were located in sensorimotor, inferior frontal and subcortical regions for fampridine- and amantadine-treated patients, and in associative sensory cortices for placebo-treated patients.
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Affiliation(s)
- Maria A Rocca
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy
| | - Paola Valsasina
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Bruno Colombo
- Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Massimo Filippi
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Neurology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy.,Neurorehabilitation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Neurophysiology Service, IRCCS San Raffaele Scientific Institute, Milan, Italy
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Sun D, Kermani M, Hudson M, He X, Unnithan RR, French C. Effects of antipsychotic drugs and potassium channel modulators on spectral properties of local field potentials in mouse hippocampus and pre-frontal cortex. Neuropharmacology 2021; 191:108572. [PMID: 33901515 DOI: 10.1016/j.neuropharm.2021.108572] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/27/2021] [Accepted: 04/12/2021] [Indexed: 01/14/2023]
Abstract
Local field potentials (LFPs) recorded intracranially display a range of location-specific oscillatory spectra which have been related to cognitive processes. Although the mechanisms producing LFPs are not completely understood, it is likely that voltage-gated ion channels which produce action potentials and patterned discharges play a significant role. It is also known that antipsychotic drugs (APDs) affect LFP spectra and a direct inhibitory effect on voltage-gated potassium channels has been reported. Additionally, voltage-gated potassium channels have been implicated in the pathophysiology of schizophrenia, a disorder for which APDs are primary therapies. In this study we sought to: i) better characterise the effects of two APDs on LFPs spectra and connectivity measures and ii) examine the effects of potassium channel modulators on LFPs and potential overlap of effects with APDs. Intracranial electrodes were implanted in hippocampus (HIP) and pre-frontal cortex (PFC) of C57BL/6J mice; power spectra, coherence and phase-amplitude cross-frequency coupling were measured. Drugs tested were APDs haloperidol and clozapine as well as voltage-gated potassium channel modulators (KVMs) 4-aminopyridine (4-AP), tetraethylammonium, retigabine and E-4031. Both APDs and KVMs significantly reduced gamma power except 4-AP, which conversely increased gamma power. Clozapine and retigabine additionally reduced gamma coherence between HIP and PFC, while 4-AP demonstrated the opposite effect. Phase-amplitude coupling between theta and gamma oscillations in HIP was significantly reduced by the administration of haloperidol and retigabine. These results provide previously undescribed effects of APDs on LFP properties and demonstrate novel modulation of LFP characteristics by KVMs that intriguingly overlap with the APD effects.
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Affiliation(s)
- Dechuan Sun
- Department of Medicine, The University of Melbourne, Victoria, Australia; Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria, Australia
| | - Mojtaba Kermani
- School of Biomedical Sciences, Monash University, Victoria, Australia
| | - Matthew Hudson
- Department of Neuroscience, Monash University, Victoria, Australia
| | - Xin He
- Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria, Australia
| | | | - Chris French
- Department of Medicine, The University of Melbourne, Victoria, Australia.
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12
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Gurjar AA, Manto KM, Estrada JA, Kaufman M, Sun D, Talukder MAH, Elfar JC. 4-Aminopyridine: A Single-Dose Diagnostic Agent to Differentiate Axonal Continuity in Nerve Injuries. Mil Med 2021; 186:479-485. [PMID: 33499448 DOI: 10.1093/milmed/usaa310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/23/2020] [Accepted: 09/22/2020] [Indexed: 12/19/2022] Open
Abstract
INTRODUCTION Traumatic peripheral nerve injuries (TPNIs) are increasingly prevalent in battlefield trauma, and the functional recovery with TPNIs depends on axonal continuity. Although the physical examination is the main tool for clinical diagnosis with diagnostic work up, there is no diagnostic tool available to differentiate nerve injuries based on axonal continuity. Therefore, treatment often relies on "watchful waiting," and this leads to muscle weakness and further reduces the chances of functional recovery. 4-aminopyridine (4-AP) is clinically used in multiple sclerosis patients for walking performance improvement. Preliminary results in conscious mice suggested a diagnostic role of 4-AP in distinguishing axonal continuity. In this study, we thought to evaluate the diagnostic potential of 4-AP on the axonal continuity in unawake/sedated animals. MATERIALS AND METHODS Rat sciatic nerve crush and transection injuries were used in this study. Briefly, rats were anesthetized with isoflurane and mechanically ventilated with oxygen-balanced vaporized isoflurane. Sciatic nerve and triceps surae muscles were exposed by blunt dissection, and a stimulating electrode was placed under a sciatic nerve proximal to the crush injury. A force transducer measured muscle tension response to electrical stimulation of sciatic nerve. Muscle response was measured before crush, after crush, and 30 minutes after systemic 4-AP (150 µg/kg) or local (4-AP)-poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA-PEG) treatment. RESULTS We found that both crush and transection injuries in sciatic nerve completely abolished muscle response to electrical stimulation. Single dose of systemic 4-AP and local (4-AP)-PLGA-PEG treatment with crush injury significantly restored muscle responses to electrical stimulation after 30 minutes of administration. However, systemic 4-AP treatment had no effect on muscle response after nerve transection. These results clearly demonstrate that 4-AP can restore nerve conduction and produce muscle response within minutes of administration only when there is a nerve continuity, even in the sedated animal. CONCLUSIONS We conclude that 4-AP could be a promising diagnostic agent in differentiating TPNI based on axonal continuity.
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Affiliation(s)
- Anagha A Gurjar
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedics and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Kristen M Manto
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedics and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Juan A Estrada
- Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Marc Kaufman
- Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Dongxiao Sun
- Mass Spectrometry Core Facility, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - M A Hassan Talukder
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedics and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - John C Elfar
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedics and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
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13
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Lewis MJ, Granger N, Jeffery ND. Emerging and Adjunctive Therapies for Spinal Cord Injury Following Acute Canine Intervertebral Disc Herniation. Front Vet Sci 2020; 7:579933. [PMID: 33195591 PMCID: PMC7593405 DOI: 10.3389/fvets.2020.579933] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/04/2020] [Indexed: 11/13/2022] Open
Abstract
Some dogs do not make a full recovery following medical or surgical management of acute canine intervertebral disc herniation (IVDH), highlighting the limits of currently available treatment options. The multitude of difficulties in treating severe spinal cord injury are well-recognized, and they have spurred intense laboratory research, resulting in a broad range of strategies that might have value in treating spinal cord-injured dogs. These include interventions that aim to directly repair the spinal cord lesion, promote axonal sparing or regeneration, mitigate secondary injury through neuroprotective mechanisms, or facilitate functional compensation. Despite initial promise in experimental models, many of these techniques have failed or shown mild efficacy in clinical trials in humans and dogs, although high quality evidence is lacking for many of these interventions. However, the continued introduction of new options to the veterinary clinic remains important for expanding our understanding of the mechanisms of injury and repair and for development of novel and combined strategies for severely affected dogs. This review outlines adjunctive or emerging therapies that have been proposed as treatment options for dogs with acute IVDH, including discussion of local or lesion-based approaches as well as systemically applied treatments in both acute and subacute-to-chronic settings. These interventions include low-level laser therapy, electromagnetic fields or oscillating electrical fields, adjunctive surgical techniques (myelotomy or durotomy), systemically or locally-applied hypothermia, neuroprotective chemicals, physical rehabilitation, hyperbaric oxygen therapy, electroacupuncture, electrical stimulation of the spinal cord or specific peripheral nerves, nerve grafting strategies, 4-aminopyridine, chondroitinase ABC, and cell transplantation.
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Affiliation(s)
- Melissa J Lewis
- Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN, United States
| | - Nicolas Granger
- The Royal Veterinary College, University of London, Hertfordshire, United Kingdom.,CVS Referrals, Bristol Veterinary Specialists at Highcroft, Bristol, United Kingdom
| | - Nick D Jeffery
- Department of Small Animal Clinical Sciences, Texas A & M College of Veterinary Medicine and Biomedical Sciences, College Station, TX, United States
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14
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The effects of temperature on the biophysical properties of optic nerve F-fibres. Sci Rep 2020; 10:12755. [PMID: 32728166 PMCID: PMC7391707 DOI: 10.1038/s41598-020-69728-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 07/15/2020] [Indexed: 01/29/2023] Open
Abstract
In multiple sclerosis, exacerbation of symptoms with rising body temperature is associated with impulse conduction failure. The mechanism is not fully understood. Remarkably, normal optic nerve axons also show temperature dependent effects, with a fall in excitability with warming. Here we show two properties of optic nerve axons, accommodation and inward rectification (Ih), respond to temperature changes in a manner consistent with a temperature dependent membrane potential. As we could find no evidence for the functional expression of KV7.2 in the axons, using the K+ channel blocker tetraethylammonium ions, we suggest this may explain the membrane potential lability. In order to understand how the axonal membrane potential may show temperature dependence, we have developed a hypothesis involving the electroneutral movement of Na+ ions across the axon membrane, that increases with increasing temperature with an appropriate Q10. Part, but probably not all, of the electroneutral Na+ movement is eliminated by removing extracellular Cl− or exposure to bumetanide, consistent with the involvement of the transporter NKCC1. Numerical simulation suggests a change in membrane potential of − 15–20 mV mimics altering temperature between room and physiological in the largest axons.
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15
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Wu ZZ, Chen SR, Pan HL. Reply to Meriney and Lacomis: Comment on direct aminopyridine effects on voltage-gated Ca 2+ channels. J Biol Chem 2020; 293:16101. [PMID: 30315088 DOI: 10.1074/jbc.rl118.005655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Zi-Zhen Wu
- From the Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205 and
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
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16
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Chakraborty S, Roy M, Saha R. Cost-effective synthesis method of facile environment friendly SnO 2 nanoparticle for efficient photocatalytic degradation of water contaminating compound. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 81:508-517. [PMID: 32385204 DOI: 10.2166/wst.2020.130] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The present study demonstrates an intensive experimental work based on the tin oxide (SnO2) nanoparticle synthesis which was successfully carried out by a simple conventional precipitation method followed by calcination at 700 °C. The synthesized nanoparticles were characterized by X-ray powder diffraction (XRD), UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern proves that tetragonal rutile structure SnO2 nanoparticles were formed. The crystallite particle size calculation from Scherer's equation revealed the average size of 28.5 nm. The absorption spectrum of SnO2 nanoparticles showed absorption band at about 290 nm and the band gap energy (Eg) from Tauc plot was obtained at 3.8 eV. The photocatalytic degradation of pharmaceutical compound, 4-aminopyridine (5 ppm) using synthesized SnO2 nanoparticle, was assessed. The effect of variable catalyst dosage, pH and irradiation sources, were studied. The optimum catalyst dosage and pH were found to be 1.5 gm/L and 6.5, respectively. The degradation efficiency of water contaminant 4-aminopyridine under UV light and solar light irradiation for 120 min were found to be 97% and 11%, respectively. The reusability of the catalyst was checked and has been found stable after three photocatalytic runs.
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Affiliation(s)
- Sucharita Chakraborty
- Department of Chemistry, National Institute of Technology, Durgapur 713209, West Bengal, India E-mail:
| | - Mouni Roy
- Department of Chemistry, National Institute of Technology, Durgapur 713209, West Bengal, India E-mail:
| | - Rajnarayan Saha
- Department of Chemistry, National Institute of Technology, Durgapur 713209, West Bengal, India E-mail:
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17
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Hsu CG, Talukder MAH, Yue L, Turpin LC, Noble M, Elfar JC. Human equivalent dose of oral 4-aminopyridine differentiates nerve crush injury from transection injury and improves post-injury function in mice. Neural Regen Res 2020; 15:2098-2107. [PMID: 32394968 PMCID: PMC7716044 DOI: 10.4103/1673-5374.280319] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
4-Aminopyridine (4-AP), an FDA-approved drug for the symptomatic treatment of multiple sclerosis, is used to improve neuromuscular function in patients with diverse demyelinating disorders. We recently demonstrated that local, transdermal or injectable forms of 4-AP improve myelination, nerve conduction velocity, muscle atrophy, and motor function after traumatic peripheral nerve injury in mice. While oral 4-AP is most commonly used in the clinic, it is unknown whether human equivalent oral doses of 4-AP have effects on traumatic peripheral nerve injury differentiation, myelination, muscle atrophy, functional recovery, and post-injury inflammatory processes in animals. Mice with sciatic nerve crush or denervation injury received oral or intraperitoneal 4-AP (10 μg) or vehicle alone and were examined for pharmacokinetics, motor function, muscle mass, intrinsic muscle force, nerve morphological and gene expression profiles. 4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to 4-AP dose. Acute single dose of oral 4-AP administration induced a rapid transient improvement in motor function that was different in traumatic peripheral nerve injury with or without nerve continuity, chronic daily oral 4-AP treatment significantly enhanced post crush injury motor function recovery and this effect was associated with improved myelination, muscle mass, and ex vivo muscle force. Polymerase chain reaction array analysis with crushed nerve revealed significant alterations in gene involved in axonal inflammation and regeneration. These findings provide convincing evidence that regardless of the route of administration, 4-AP can acutely differentiate traumatic peripheral nerve injury with or without nerve continuity and can enhance in vivo functional recovery with better preservation of myelin sheaths, muscle mass, and muscle force. The animal experiments were approved by the University Committee on Animal Research (UCAR) at the University of Rochester (UCAR-2009-019) on March 31, 2017.
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Affiliation(s)
- Chia George Hsu
- Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - M A Hassan Talukder
- Center for Orthopaedic Research and Translational Science, Penn State Hershey College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA
| | - Li Yue
- Department of Orthopedics, The Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Loel C Turpin
- Department of Neuroscience, The University of Rochester Medical Center, Rochester, NY, USA
| | - Mark Noble
- Department of Biomedical Genetics, The University of Rochester Medical Center, Rochester, NY, USA
| | - John C Elfar
- Center for Orthopaedic Research and Translational Science, Penn State Hershey College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA
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18
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Modrak M, Talukder MAH, Gurgenashvili K, Noble M, Elfar JC. Peripheral nerve injury and myelination: Potential therapeutic strategies. J Neurosci Res 2019; 98:780-795. [PMID: 31608497 DOI: 10.1002/jnr.24538] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 08/30/2019] [Accepted: 09/16/2019] [Indexed: 12/11/2022]
Abstract
Traumatic peripheral nerve injury represents a major clinical and public health problem that often leads to significant functional impairment and permanent disability. Despite modern diagnostic procedures and advanced microsurgical techniques, functional recovery after peripheral nerve repair is often unsatisfactory. Therefore, there is an unmet need for new therapeutic or adjunctive strategies to promote the functional recovery in nerve injury patients. In contrast to the central nervous system, Schwann cells in the peripheral nervous system play a pivotal role in several aspects of nerve repair such as degeneration, remyelination, and axonal growth. Several non-surgical approaches, including pharmacological, electrical, cell-based, and laser therapies, have been employed to promote myelination and enhance functional recovery after peripheral nerve injury. This review will succinctly discuss the potential therapeutic strategies in the context of myelination following peripheral neurotrauma.
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Affiliation(s)
- Max Modrak
- School of Medicine & Dentistry, The University of Rochester Medical Center, Rochester, New York, USA
| | - M A Hassan Talukder
- Department of Orthopaedics & Rehabilitation, Penn State Hershey College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Khatuna Gurgenashvili
- Department of Neurology, Penn State Hershey College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Mark Noble
- Department of Biomedical Genetics, The University of Rochester Medical Center, Rochester, New York, USA
| | - John C Elfar
- Department of Orthopaedics & Rehabilitation, Penn State Hershey College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
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19
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Kostadinova I, Danchev N. 4-aminopyridine – the new old drug for the treatment of neurodegenerative diseases. PHARMACIA 2019. [DOI: 10.3897/pharmacia.66.e35976] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In this review are described the preclinical and clinical pharmacological data as well as new therapeutic indications for the use of 4-aminopyridine. 4-aminopyridine is a potassium (K+) channel blocker that has a long history and various application areas. It is a chemical agent developed in 1963 as a bird poison. The first approval for clinical application of 4-aminopyridine was in 70’s in Bulgaria, since anesthetists in that country have confirmed its effect as reversal agent for nondepolarizing myorelaxants. The Bulgarian pharmaceutical company Sopharma commersialized 4-aminopyridine under the trade name Pymadin. Since then 4-aminopyridine was extensively studied and in 2010 is approved in the USA for the treatment of walking disabilities in patients with multiple sclerosis. In recent years, data from clinical trials indicated that K-channel blockade may prove to be an appropriate strategy to overcome disturbances in nerve impulses conduction associated with demyelination of the central nervous system.
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20
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Lewis MJ, Laber E, Olby NJ. Predictors of Response to 4-Aminopyridine in Chronic Canine Spinal Cord Injury. J Neurotrauma 2018; 36:1428-1434. [PMID: 30235970 DOI: 10.1089/neu.2018.5975] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
4-Aminopyridine (4AP), a potassium channel antagonist, can improve hindlimb motor function in dogs with chronic thoracolumbar spinal cord injury (SCI); however, individual response is variable. We hypothesized that injury characteristics would differ between dogs that do and do not respond to 4AP. Our objective was to compare clinical, electrodiagnostic, gait, and imaging variables between dogs that do and do not respond to 4AP, to identify predictors of response. Thirty-four dogs with permanent deficits after acute thoracolumbar SCI were enrolled. Spasticity, motor and sensory evoked potentials (MEPs, SEPs), H-reflex, F-waves, gait scores, and magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) were evaluated at baseline and after 4AP administration. Baseline variables were assessed as predictors of response; response was defined as ≥1 point change in open field gait score. Variables were compared pre- and post-4AP to evaluate 4AP effects. Fifteen of 33 (45%) dogs were responders, 18/33 (55%) were non-responders and 1 was eliminated because of an adverse event. Pre-H-reflex threshold <1.2 mA predicted non-response; pre-H-reflex threshold >1.2 mA and Canine Spasticity Scale overall score <7 were predictive of response. All responders had translesional connections on DTI. MEPs were more common post-4AP than pre-4AP (10 vs. 6 dogs) and 4AP decreased H-reflex threshold and increased spasticity in responders. 4-AP impacts central conduction and motor neuron pool excitability in dogs with chronic SCI. Severity of spasticity and H-reflex threshold might allow prediction of response. Further exploration of electrodiagnostic and imaging characteristics might elucidate additional factors contributing to response or non-response.
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Affiliation(s)
- Melissa J Lewis
- 1 Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana
| | - Eric Laber
- 2 Department of Statistics, College of Sciences, North Carolina State University, Raleigh, North Carolina
| | - Natasha J Olby
- 3 Department of Clinical Sciences, College of Veterinary Medicine, and North Carolina State University, Raleigh, North Carolina.,4 Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina
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21
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Leussink VI, Montalban X, Hartung HP. Restoring Axonal Function with 4-Aminopyridine: Clinical Efficacy in Multiple Sclerosis and Beyond. CNS Drugs 2018; 32:637-651. [PMID: 29992409 DOI: 10.1007/s40263-018-0536-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The oral potassium channel blocker 4-aminopyridine has been used in various neurological conditions for decades. Numerous case reports and studies have supported its clinical efficacy in ameliorating the clinical presentation of certain neurological disorders. However, its short half-life, erratic drug levels, and safety-related dose restrictions limited its use as a self-compounded drug in clinical practice. This changed with the introduction of a prolonged-release formulation, which was successfully tested in patients with multiple sclerosis. It was fully approved by the US FDA in January 2010 but initially received only conditional approval from the European Medicines Agency (EMA) in July 2011. After additional clinical studies, this conditional approval was changed to unrestricted approval in August 2017. This article reviews and discusses these recent studies and places aminopyridines and their clinical utility into the context of a broader spectrum of neurological disorders, where clinical efficacy has been suggested. In 2010, prolonged-release 4-aminopyridine became the first drug specifically licensed to improve walking in patients with multiple sclerosis. About one-third of patients across disease courses benefit from this treatment. In addition, various reports indicate clinical efficacy beyond multiple sclerosis, which may broaden its use in clinical practice.
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Affiliation(s)
| | - Xavier Montalban
- Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Hospital Universitario Vall d'Hebron, Barcelona, Spain.,St. Michael's Hospital, University of Toronto, Toronto, Canada
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany.
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22
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Kaczmarek D, Jankowska E. DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC. Neuroscience 2018; 374:236-249. [DOI: 10.1016/j.neuroscience.2018.01.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/16/2018] [Accepted: 01/17/2018] [Indexed: 12/20/2022]
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23
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Daneshi Kohan E, Lashkari BS, Sparrey CJ. The effects of paranodal myelin damage on action potential depend on axonal structure. Med Biol Eng Comput 2017; 56:395-411. [PMID: 28770425 DOI: 10.1007/s11517-017-1691-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 07/17/2017] [Indexed: 12/31/2022]
Abstract
Biophysical computational models of axons provide an important tool for quantifying the effects of injury and disease on signal conduction characteristics. Several studies have used generic models to study the average behavior of healthy and injured axons; however, few studies have included the effects of normal structural variation on the simulated axon's response to injury. The effects of variations in physiological characteristics on axonal function were mapped by altering the structure of the nodal, paranodal, and juxtaparanodal regions across reported values in three different caliber axons (1, 2, and 5.7 μm). Myelin detachment and retraction were simulated to quantify the effects of each injury mechanism on signal conduction. Conduction velocity was most affected by axonal fiber diameter (89%), while membrane potential amplitude was most affected by nodal length (86%) in healthy axons. Postinjury axonal functionality was most affected by myelin detachment in the paranodal and juxtaparanodal regions when retraction and detachment were modeled simultaneously. The efficacy of simulated potassium channel blockers on restoring membrane potential and velocity varied with axonal caliber and injury type. The structural characteristics of axons affect their functional response to myelin retraction and detachment and their subsequent response to potassium channel blocker treatment.
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Affiliation(s)
- Ehsan Daneshi Kohan
- Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC, V3T 0A3, Canada.,International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, 5th floor, 5200, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
| | - Behnia Shadab Lashkari
- International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, 5th floor, 5200, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
| | - Carolyn Jennifer Sparrey
- Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC, V3T 0A3, Canada. .,International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, 5th floor, 5200, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
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24
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Hardmeier M, Leocani L, Fuhr P. A new role for evoked potentials in MS? Repurposing evoked potentials as biomarkers for clinical trials in MS. Mult Scler 2017; 23:1309-1319. [PMID: 28480798 PMCID: PMC5564950 DOI: 10.1177/1352458517707265] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Evoked potentials (EP) characterize signal conduction in selected tracts of the central nervous system in a quantifiable way. Since alteration of signal conduction is the main mechanism of symptoms and signs in multiple sclerosis (MS), multimodal EP may serve as a representative measure of the functional impairment in MS. Moreover, EP have been shown to be predictive for disease course, and thus might help to select patient groups at high risk of progression for clinical trials. EP can detect deterioration, as well as improvement of impulse propagation, independently from the mechanism causing the change. Therefore, they are candidates for biomarkers with application in clinical phase-II trials. Applicability of EP in multicenter trials has been limited by different standards of registration and assessment.
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Affiliation(s)
- Martin Hardmeier
- Section of Clinical Neurophysiology, Department of Neurology, University Hospital of Basel, Basel, Switzerland
| | - Letizia Leocani
- Neurological Department and Institute of Experimental Neurology (INSPE) Scientific Institute, University Hospital San Raffaele, Milan, Italy
| | - Peter Fuhr
- Section of Clinical Neurophysiology, Department of Neurology, University Hospital of Basel, Basel, Switzerland
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25
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Ayache SS, Chalah MA. Fatigue in multiple sclerosis – Insights into evaluation and management. Neurophysiol Clin 2017; 47:139-171. [DOI: 10.1016/j.neucli.2017.02.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/15/2017] [Indexed: 12/20/2022] Open
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26
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Sindhurakar A, Mishra AM, Gupta D, Iaci JF, Parry TJ, Carmel JB. Clinically Relevant Levels of 4-Aminopyridine Strengthen Physiological Responses in Intact Motor Circuits in Rats, Especially After Pyramidal Tract Injury. Neurorehabil Neural Repair 2017; 31:387-396. [PMID: 28107804 DOI: 10.1177/1545968316688800] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND 4-Aminopyridine (4-AP) is a Food and Drug Administration-approved drug to improve motor function in people with multiple sclerosis. Preliminary results suggest the drug may act on intact neural circuits and not just on demyelinated ones. OBJECTIVE To determine if 4-AP at clinically relevant levels alters the excitability of intact motor circuits. METHODS In anesthetized rats, electrodes were placed over motor cortex and the dorsal cervical spinal cord for electrical stimulation, and electromyogram electrodes were inserted into biceps muscle to measure responses. The motor responses to brain and spinal cord stimulation were measured before and for 5 hours after 4-AP administration both in uninjured rats and rats with a cut lesion of the pyramidal tract. Blood was collected at the same time as electrophysiology to determine drug plasma concentration with a goal of 20 to 100 ng/mL. RESULTS We first determined that a bolus infusion of 0.32 mg/kg 4-AP was optimal: it produced on average 61.5 ± 1.8 ng/mL over the 5 hours after infusion. This dose of 4-AP increased responses to spinal cord stimulation by 1.3-fold in uninjured rats and 3-fold in rats with pyramidal tract lesion. Responses to cortical stimulation also increased by 2-fold in uninjured rats and up to 4-fold in the injured. CONCLUSION Clinically relevant levels of 4-AP strongly augment physiological responses in intact circuits, an effect that was more robust after partial injury, demonstrating its broad potential in treating central nervous system injuries.
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Affiliation(s)
| | - Asht M Mishra
- 1 Burke Medical Research Institute, White Plains, NY, USA
| | - Disha Gupta
- 1 Burke Medical Research Institute, White Plains, NY, USA.,2 Weill Cornell Medicine, New York, NY, USA
| | | | | | - Jason B Carmel
- 1 Burke Medical Research Institute, White Plains, NY, USA.,2 Weill Cornell Medicine, New York, NY, USA
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Korsen M, Kunz R, Schminke U, Runge U, Kohlmann T, Dressel A. Dalfampridine effects on cognition, fatigue, and dexterity. Brain Behav 2017; 7:e00559. [PMID: 28127507 PMCID: PMC5256171 DOI: 10.1002/brb3.559] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 06/29/2016] [Accepted: 07/01/2016] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVES Dalfampridine exerts beneficial effects on walking ability in a subgroup of patients with multiple sclerosis (MS). These patients are termed "responders". Here, we investigated whether the responder status with respect to mobility measures would determine whether dalfampridine treatment exerts a beneficial effect on other MS symptoms. We therefore assessed walking ability, upper limb function, cognition, fatigue, visual evoked potentials (VEPs), depression, and quality of life in patients before and after dalfampridine treatment. METHODS Patients with MS and impaired mobility were recruited. Maximal walking distance, timed 25 Foot Walk, nine hole peg test, paced auditory serial addition test (PASAT), fatigue severity scale (FSS), VEPs, Beck Depression Inventory (BDI), EuroQol five dimensional questionnaire, and quality of life visual analogue scale were determined before and after 12-14 days of dalfampridine treatment. Repeated measures analysis of variance was applied to determine the effect of dalfampridine treatment. RESULTS Of the 34 patients who completed the study, 22 patients were responders and 12 patients nonresponders, according to their performance in mobility measures. Treatment effects for the entire patient cohort were observed for PASAT (p = .029) and BDI (p = .032). Belonging to the responder cohort did not predict the response to treatment in these tests. For the FSS, response to dalfampridine treatment was dependent on the responder status (p = .001) while no effects in the total patient cohort were observed (p = .680). Other neurological functions remained unaltered. For VEP latencies, no significant improvements were detected. CONCLUSION In this study, we observed beneficial effects of dalfampridine on cognition, depression, and fatigue. These effects were not limited to patients who responded to dalfampridine with improved mobility measures. These findings underscore the need to assess the beneficial effects of dalfampridine on neurological deficits in MS patients in additional randomized clinical trials.
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Affiliation(s)
- Melanie Korsen
- Department of Neurology University Medicine Greifswald Greifswald Germany
| | - Rhina Kunz
- Department of Neurology University Medicine Greifswald Greifswald Germany
| | - Ulf Schminke
- Department of Neurology University Medicine Greifswald Greifswald Germany
| | - Uwe Runge
- Department of Neurology University Medicine Greifswald Greifswald Germany
| | - Thomas Kohlmann
- Institute of Community Medicine University Medicine Greifswald Greifswald Germany
| | - Alexander Dressel
- Department of Neurology University Medicine Greifswald Greifswald Germany; Department of Neurology Carl-Thiem-Klinikum Cottbus Cottbus Germany
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Kasatkina LA. 4-Аminopyridine sequesters intracellular Ca 2+ which triggers exocytosis in excitable and non-excitable cells. Sci Rep 2016; 6:34749. [PMID: 27703262 PMCID: PMC5050491 DOI: 10.1038/srep34749] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 09/16/2016] [Indexed: 12/19/2022] Open
Abstract
4-aminopyridine is commonly used to stimulate neurotransmitter release resulting from sustained plasma membrane depolarization and Ca2+-influx from the extracellular space. This paper elucidated unconventional mechanism of 4-aminopyridine-stimulated glutamate release from neurons and non-neuronal cells which proceeds in the absence of external Ca2+. In brain nerve terminals, primary neurons and platelets 4-aminopyridine induced the exocytotic release of glutamate that was independent of external Ca2+ and was triggered by the sequestration of Ca2+ from intracellular stores. The initial level of 4-aminopyridine-stimulated glutamate release from neurons in the absence or presence of external Ca2+ was subequal and the difference was predominantly associated with subsequent tonic release of glutamate in Ca2+-supplemented medium. The increase in [Ca2+]i and the secretion of glutamate stimulated by 4-aminopyridine in Ca2+-free conditions have resulted from Ca2+ efflux from endoplasmic reticulum and were abolished by intracellular free Ca2+ chelator BAPTA. This suggests that Ca2+ sequestration plays a profound role in the 4-aminopyridine-mediated stimulation of excitable and non-excitable cells. 4-Aminopyridine combines the properties of depolarizing agent with the ability to sequester intracellular Ca2+. The study unmasks additional mechanism of action of 4-aminopyridine, an active substance of drugs for treatment of multiple sclerosis and conditions related to reduced Ca2+ efflux from intracellular stores.
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Affiliation(s)
- Ludmila A Kasatkina
- The Department of Neurochemistry, Palladin Institute of Biochemistry, NAS of Ukraine 9, Leontovicha Street, Kyiv, 01030, Ukraine
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Brambilla L, Rossi Sebastiano D, Aquino D, Torri Clerici V, Brenna G, Moscatelli M, Frangiamore R, Giovannetti AM, Antozzi C, Mantegazza R, Franceschetti S, Bruzzone MG, Erbetta A, Confalonieri P. Early effect of dalfampridine in patients with MS: A multi-instrumental approach to better investigate responsiveness. J Neurol Sci 2016; 368:402-7. [PMID: 27538672 DOI: 10.1016/j.jns.2016.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 11/18/2022]
Abstract
BACKGROUND 4-aminopyridine (4-AP) is a potassium-channel blocker able to enhance walking speed in MS improving the action potentials of demyelinated axons on which internodal potassium channels are exposed. OBJECTIVE to study early 4-AP effect with clinical, subjective, neurophysiological and neuroradiological tools. METHODS Clinical (Timed 25-Foot Walk - T25FW, Timed Up-And-Go - TUG), subjective (MS Walking Scale-12 - MSWS-12), neurophysiological (Motor Evoked Potentials - MEPs) and imaging (Diffusion Tensor Imaging - DTI) evaluations were performed before (T0) and after (T1) 14days of 4-AP treatment. MEPs were recorded from Abductor Hallucis of both legs. A Tract-Based-Spatial-Statistics (TBSS) was performed on DTI. RESULTS We found a significant difference between T0 and T1 for T25FW, TUG, MSWS-12 (p≤0.001) in the whole patients' sample (23 subjects, median EDSS 6.0) and decrease of Central Motor Conduction Time and increase of mean Amplitude (Amp) at T1 (p=0.008 and p=0.006). We also recorded a significant difference of T25FW, TUG, MSWS-12 and Amp in clinical responder (CR) patients (CR: amelioration >20% at T25FW). TBSS showed a significant Mean and Radial Diffusivity reduction in the corticospinal tracts (p<0.05) of the whole group of patients; this reduction was also found in the CR subgroup. CONCLUSION Neurophysiological and neuroradiological parameters were modified in MS patients treated with 4-AP, and most of them reported a subjective improvement of their motor performances after treatment. The use of clinical, subjective, neurophysiological and neuroradiological tools could help to better explore MS patients responsiveness to 4-AP.
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Affiliation(s)
- L Brambilla
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy.
| | - D Rossi Sebastiano
- Department of Neurophysiology, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - D Aquino
- Department of Neuroradiology, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - V Torri Clerici
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - G Brenna
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - M Moscatelli
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy; University of Milan, Via Festa del Perdono 7, 20122 Milan, Italy
| | - R Frangiamore
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - A M Giovannetti
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - C Antozzi
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - R Mantegazza
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - S Franceschetti
- Department of Neurophysiology, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - M G Bruzzone
- Department of Neuroradiology, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - A Erbetta
- Department of Neuroradiology, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
| | - P Confalonieri
- Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta IRCCS Foundation, Milan, Italy
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Romani A, Bergamaschi R, Candeloro E, Alfonsi E, Callieco R, Cosi V. Fatigue in multiple sclerosis: multidimensional assessment and response to symptomatic treatment. Mult Scler 2016; 10:462-8. [PMID: 15327047 DOI: 10.1191/1352458504ms1051oa] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sixty relapsing-remitting multiple sclerosis (MS) patients were selected on the basis of their score on the Fatigue Severity Scale (FSS) and formed two groups: 40 patients (fatigued MS; MSf) scored above the 75th percentile of a previously assessed representative MS sample (100 patients), and 20 age- and sex-matched patients (nonfatigued MS patients; MSnf) scored below the 25th percentile. The patients underwent clinical evaluation (Expanded Disability Status Scale (EDSS)), further assessment of fatigue (Fatigue Impact Scale), scales evaluating depression (Hamilton Depression Rating Scale (HDRS) and Beck’s Depression Inventory (BDI)) and neuropsychological tests. All patients were evaluated for muscle fatigability and central activation by means of a biomechanical test of sustained contraction; they also underwent somatosensory evoked potentials (SSEPs) and transcranial magnetic stimulation (TMS). The patients of the MSf subgroup were then randomized to one of the following two treatments: 4-aminopyridine (4-AP) 24 mg/day and fluoxetine (FLX) 20 mg/day. After a one-week titration this treatment proceeded for 8 weeks. At the end of the treatment, EDSS, fatigue and depression scores were further evaluated. At baseline, fatigue test scores consistently correlated with depression and cognitive test scores, but not with the fatigability test. Fatigue scores decreased in both treatment groups in a similar way. Due to the design of the study, this cannot be disjoined from a placebo effect. The changes of fatigue scores could not be predicted in the FLX group, whereas in the 4-AP group higher basal fatigability test scores were associated with greater reduction in fatigue scores.
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Affiliation(s)
- Alfredo Romani
- Laboratorio Potenziali Evocati, Istituto Neurologico C. Mondino, Pavia, Italy.
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Huynh W, Pickering H, Howells J, Murray J, Cormack C, Lin CSY, Vucic S, Kiernan MC, Krishnan AV. Effect of fampridine on axonal excitability in multiple sclerosis. Clin Neurophysiol 2016; 127:2636-42. [PMID: 27291883 DOI: 10.1016/j.clinph.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/15/2016] [Accepted: 04/05/2016] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To investigate the effects of fampridine on nerve excitability, the present study utilized peripheral axonal excitability techniques in 18 MS patients receiving treatment with fampridine. METHODS Studies were performed at baseline and repeated 3months after institution of fampridine at standard dosing. RESULTS Following treatment with fampridine there were significant changes in axonal excitability for those parameters associated with fast K(+) channels that shifted towards normal control values. Specifically, increases were noted in the peak superexcitability of recovery cycle (fampridine, -25.6±1.6%; baseline -22.8±1.7%; p<0.004), peak depolarizing threshold electrotonus (fampridine, 69.1±1.0%; baseline 67.0±1.4%; p<0.004), and depolarizing threshold electrotonus between 40 and 60ms after onset of depolarization (fampridine, 52.8±1.3%; baseline 49.9±1.4%; p=0.02). CONCLUSION The present study has established that fampridine at standard doses exerts effects on peripheral nerve function that may be mediated by reduction of fast K(+) conductances. SIGNIFICANCE Modulation of fast K(+) conductances by fampridine may contribute to the improvement observed in MS symptoms including motor fatigue.
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Affiliation(s)
- William Huynh
- Brain and Mind Centre, University of Sydney, New South Wales, Australia; Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia.
| | - Hannah Pickering
- School of Medical Sciences, University of New South Wales, New South Wales, Australia
| | - James Howells
- Brain and Mind Centre, University of Sydney, New South Wales, Australia
| | - Jenna Murray
- Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia
| | - Christine Cormack
- Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia
| | - Cindy S-Y Lin
- School of Medical Sciences, University of New South Wales, New South Wales, Australia
| | - Steve Vucic
- Western Clinical School, University of Sydney, New South Wales, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney, New South Wales, Australia
| | - Arun V Krishnan
- Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia
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Leussink VI, Stettner M, Warnke C, Hartung HP. Fampridine-PR (prolonged released 4-aminopyridine) is not effective in patients with inflammatory demyelination of the peripheral nervous system. J Peripher Nerv Syst 2016; 21:85-7. [DOI: 10.1111/jns.12169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 03/07/2016] [Indexed: 12/11/2022]
Affiliation(s)
| | - Mark Stettner
- Department of Neurology, Medical Faculty; Heinrich-Heine-University; Düsseldorf Germany
| | - Clemens Warnke
- Department of Neurology, Medical Faculty; Heinrich-Heine-University; Düsseldorf Germany
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty; Heinrich-Heine-University; Düsseldorf Germany
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Restoration of Visual Function by Enhancing Conduction in Regenerated Axons. Cell 2016; 164:219-232. [PMID: 26771493 DOI: 10.1016/j.cell.2015.11.036] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/01/2015] [Accepted: 11/06/2015] [Indexed: 01/19/2023]
Abstract
Although a number of repair strategies have been shown to promote axon outgrowth following neuronal injury in the mammalian CNS, it remains unclear whether regenerated axons establish functional synapses and support behavior. Here, in both juvenile and adult mice, we show that either PTEN and SOCS3 co-deletion, or co-overexpression of osteopontin (OPN)/insulin-like growth factor 1 (IGF1)/ciliary neurotrophic factor (CNTF), induces regrowth of retinal axons and formation of functional synapses in the superior colliculus (SC) but not significant recovery of visual function. Further analyses suggest that regenerated axons fail to conduct action potentials from the eye to the SC due to lack of myelination. Consistent with this idea, administration of voltage-gated potassium channel blockers restores conduction and results in increased visual acuity. Thus, enhancing both regeneration and conduction effectively improves function after retinal axon injury.
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Kastriti ME, Sargiannidou I, Kleopa KA, Karagogeos D. Differential modulation of the juxtaparanodal complex in Multiple Sclerosis. Mol Cell Neurosci 2015; 67:93-103. [DOI: 10.1016/j.mcn.2015.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/25/2015] [Accepted: 06/08/2015] [Indexed: 12/23/2022] Open
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Abnormal excitability and episodic low-frequency oscillations in the cerebral cortex of the tottering mouse. J Neurosci 2015; 35:5664-79. [PMID: 25855180 DOI: 10.1523/jneurosci.3107-14.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Ca(2+) channelopathies caused by mutations of the CACNA1A gene that encodes the pore-forming subunit of the human Cav2.1 (P/Q-type) voltage-gated Ca(2+) channel include episodic ataxia type 2 (EA2). Although, in EA2 the emphasis has been on cerebellar dysfunction, patients also exhibit episodic, nonmotoric abnormalities involving the cerebral cortex. This study demonstrates episodic, low-frequency oscillations (LFOs) throughout the cerebral cortex of tottering (tg/tg) mice, a widely used model of EA2. Ranging between 0.035 and 0.11 Hz, the LFOs in tg/tg mice can spontaneously develop very high power, referred to as a high-power state. The LFOs in tg/tg mice are mediated in part by neuronal activity as tetrodotoxin decreases the oscillations and cortical neuron discharge contain the same low frequencies. The high-power state involves compensatory mechanisms because acutely decreasing P/Q-type Ca(2+) channel function in either wild-type (WT) or tg/tg mice does not induce the high-power state. In contrast, blocking l-type Ca(2+) channels, known to be upregulated in tg/tg mice, reduces the high-power state. Intriguingly, basal excitatory glutamatergic neurotransmission constrains the high-power state because blocking ionotropic or metabotropic glutamate receptors results in high-power LFOs in tg/tg but not WT mice. The high-power LFOs are decreased markedly by acetazolamide and 4-aminopyridine, the primary treatments for EA2, suggesting disease relevance. Together, these results demonstrate that the high-power LFOs in the tg/tg cerebral cortex represent a highly abnormal excitability state that may underlie noncerebellar symptoms that characterize CACNA1A mutations.
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Lim JH, Muguet-Chanoit AC, Smith DT, Laber E, Olby NJ. Potassium channel antagonists 4-aminopyridine and the T-butyl carbamate derivative of 4-aminopyridine improve hind limb function in chronically non-ambulatory dogs; a blinded, placebo-controlled trial. PLoS One 2014; 9:e116139. [PMID: 25551385 PMCID: PMC4281252 DOI: 10.1371/journal.pone.0116139] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 12/04/2014] [Indexed: 01/05/2023] Open
Abstract
4-Aminopyridine (4-AP) blocks voltage gated potassium channels, restoring conduction to demyelinated axons and improving function in demyelinating conditions, but its use is associated with adverse effects and benefit in spinal cord injury is limited. Derivatives of 4-AP have been developed to improve clinical efficacy while reducing toxicity. We compared the therapeutic effects of orally administered 4-AP and its t-butyl carbamate derivative (t-butyl) with placebo in dogs that had suffered an acute spinal cord injury that left them chronically paralyzed. Nineteen dogs were entered into the trial, conducted in two-week treatment blocks starting with placebo, followed by random assignment to 4-AP or t-butyl, a washout and then the opposite medication followed by placebo. Investigators and owners were blinded to treatment group. Primary outcome measures included open field gait score (OFS), and treadmill based stepping score and regularity index, with additional secondary measures also considered. Thirteen of 19 dogs completed the protocol. Two were euthanized due to unrelated heath problems, two developed side effects and two were unable to complete for unrelated reasons. Dogs showed significant improvement in supported stepping score (from 17.39 to 37.24% with 4-AP; 16.85 to 29.18% with t-butyl p<0.0001) and OFS (from 3.63 to 4.73 with 4-AP; 3.78 to 4.45 with t-butyl, p = 0.005). Response was individually variable and most dramatic in three dogs that were able to walk without support with treatment. No significant difference was found between 4-AP and t-butyl. No adverse effects were reported with t-butyl but gastrointestinal upset and seizures were observed in two dogs with 4-AP. In conclusion, both 4-AP and t-butyl significantly improved supported stepping ability in dogs with chronic spinal cord injury with no adverse effects noted with t-butyl. Drug response varied widely between individuals, highlighting the need to understand the factors that influence canine and human patients' response to therapy.
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Affiliation(s)
- Ji-Hey Lim
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
- Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Audrey C. Muguet-Chanoit
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Daniel T. Smith
- Department Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana, United States of America
| | - Eric Laber
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Natasha J. Olby
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
- Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
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Li L, Li DP, Chen SR, Chen J, Hu H, Pan HL. Potentiation of high voltage-activated calcium channels by 4-aminopyridine depends on subunit composition. Mol Pharmacol 2014; 86:760-72. [PMID: 25267719 PMCID: PMC4244593 DOI: 10.1124/mol.114.095505] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 09/26/2014] [Indexed: 01/12/2023] Open
Abstract
4-Aminopyridine (4-AP, fampridine) is used clinically to improve neuromuscular function in patients with multiple sclerosis, spinal cord injury, and myasthenia gravis. 4-AP can increase neuromuscular and synaptic transmission by directly stimulating high voltage-activated (HVA) Ca(2+) channels independent of its blocking effect on voltage-activated K(+) channels. Here we provide new evidence that the potentiating effect of 4-AP on HVA Ca(2+) channels depends on the specific combination of voltage-activated calcium channel α1 (Cavα1) and voltage-activated calcium channel β (Cavβ) subunits. Among the four Cavβ subunits examined, Cavβ3 was the most significant subunit involved in the 4-AP-induced potentiation of both L-type and N-type currents. Of particular note, 4-AP at micromolar concentrations selectively potentiated L-type currents reconstituted with Cav1.2, α2δ1, and Cavβ3. In contrast, 4-AP potentiated N-type currents only at much higher concentrations and had little effect on P/Q-type currents. In a phrenic nerve-diaphragm preparation, blocking L-type Ca(2+) channels eliminated the potentiating effect of low concentrations of 4-AP on end-plate potentials. Furthermore, 4-AP enhanced the physical interaction of Cav1.2 and Cav2.2 subunits to Cavβ3 and also increased their trafficking to the plasma membrane. Site-directed mutagenesis identified specific regions in the guanylate kinase, HOOK, and C-terminus domains of the Cavβ3 subunit crucial to the ability of 4-AP to potentiate L-type and N-type currents. Our findings indicate that 4-AP potentiates HVA Ca(2+) channels by enhancing reciprocal Cav1.2-Cavβ3 and Cav2.2-Cavβ3 interactions. The therapeutic effect of 4-AP on neuromuscular function is probably mediated by its actions on Cavβ3-containing L-type Ca(2+) channels.
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Affiliation(s)
- Li Li
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
| | - De-Pei Li
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
| | - Jinjun Chen
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
| | - Hongzhen Hu
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research (L.L., D.-P.L, S.-R.C., J.C., H.-L.P.), Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; College of Bioscience and Biotechnology (J.C.), Hunan Agricultural University, Changsha, P.R. China; and Department of Integrative Biology and Pharmacology (H.H.), The University of Texas Medical School, Houston, Texas
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Blight AR, Henney HR, Cohen R. Development of dalfampridine, a novel pharmacologic approach for treating walking impairment in multiple sclerosis. Ann N Y Acad Sci 2014; 1329:33-44. [PMID: 25154911 DOI: 10.1111/nyas.12512] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Walking impairment is a clinical hallmark of multiple sclerosis (MS). Dalfampridine-ER, an extended-release formulation of dalfampridine (also known by its chemical name, 4-aminopyridine, and its international nonproprietary name, fampridine), was developed to maintain drug plasma levels within a narrow therapeutic window, and assessed for its ability to improve walking in MS. The putative mechanism of action of dalfampridine-ER is restoration of axonal conduction via blockade of the potassium channels that become exposed during axonal demyelination. Two pivotal phase III clinical trials demonstrated that dalfampridine-ER 10-mg tablets administered twice daily improved walking speed and patient-reported perceptions of walking in some patients. Dalfampridine-ER was generally well tolerated, and, at the approved dose, risk of seizure was neither elevated relative to placebo nor higher than the rate in the MS population. Dalfampridine-ER (AMPYRA®) was approved in the United States for the treatment of walking in patients with MS as demonstrated by an increase in walking speed. The use of the dalfampridine-ER is contraindicated in patients with a history of seizure. It is the first pharmacologic therapy for this indication and has been incorporated into clinical management of MS.
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The node of Ranvier in CNS pathology. Acta Neuropathol 2014; 128:161-75. [PMID: 24913350 PMCID: PMC4102831 DOI: 10.1007/s00401-014-1305-z] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/27/2014] [Accepted: 05/27/2014] [Indexed: 12/11/2022]
Abstract
Healthy nodes of Ranvier are crucial for action potential propagation along myelinated axons, both in the central and in the peripheral nervous system. Surprisingly, the node of Ranvier has often been neglected when describing CNS disorders, with most pathologies classified simply as being due to neuronal defects in the grey matter or due to oligodendrocyte damage in the white matter. However, recent studies have highlighted changes that occur in pathological conditions at the node of Ranvier, and at the associated paranodal and juxtaparanodal regions where neurons and myelinating glial cells interact. Lengthening of the node of Ranvier, failure of the electrically resistive seal between the myelin and the axon at the paranode, and retraction of myelin to expose voltage-gated K+ channels in the juxtaparanode, may contribute to altering the function of myelinated axons in a wide range of diseases, including stroke, spinal cord injury and multiple sclerosis. Here, we review the principles by which the node of Ranvier operates and its molecular structure, and thus explain how defects at the node and paranode contribute to neurological disorders.
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Zeller D, Reiners K, Bräuninger S, Buttmann M. Central motor conduction time may predict response to fampridine in patients with multiple sclerosis. J Neurol Neurosurg Psychiatry 2014; 85:707-9. [PMID: 24357684 PMCID: PMC4033025 DOI: 10.1136/jnnp-2013-306860] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D Zeller
- Department of Neurology, University of Würzburg, , Würzburg, Germany
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Frejo MT, del Pino J, Lobo M, García J, Capo MA, Díaz MJ. Liver and kidney damage induced by 4-aminopyridine in a repeated dose (28 days) oral toxicity study in rats: Gene expression profile of hybrid cell death. Toxicol Lett 2014; 225:252-63. [DOI: 10.1016/j.toxlet.2013.12.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022]
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Jensen HB, Ravnborg M, Dalgas U, Stenager E. 4-Aminopyridine for symptomatic treatment of multiple sclerosis: a systematic review. Ther Adv Neurol Disord 2014; 7:97-113. [PMID: 24587826 PMCID: PMC3932769 DOI: 10.1177/1756285613512712] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
This systematic review summarizes the existing evidence on the effect of 4-aminopyridine (4-AP) as a symptomatic treatment of decreased walking capacity in patients with multiple sclerosis (MS) when administered as an immediate release compound and a slow release compound. It summarizes existing evidence on the basic mechanisms of 4-AP from experimental studies and evidence on the clinical use of the compound. A systematic literature search was conducted of the following databases: PubMed and EMBASE. Thirty-five studies were included in the review divided into 16 experimental studies, two clinical studies with paraclinical endpoints and 17 clinical studies with clinical endpoints. Animal studies show that 4-AP can improve impulse conduction through demyelinated lesions. In patients with MS this translates into improved walking speed and muscle strength of the lower extremities in a subset of patients at a level that is often of clinical relevance. Phase III trials demonstrate approximately 25% increase in walking speed in roughly 40% and improved muscle strength in the lower extremities. Furthermore, 4-AP might have an effect on other domains such as cognition, upper extremity function and bowel and bladder, but this warrants further investigation. Side effects are mainly mild to moderate, consisting primarily of paraesthesia, dizziness, nausea/vomiting, falls/balance disorders, insomnia, urinary tract infections and asthenia. Side effects are worse when administered intravenously and when administered as an immediate release compound. Serious adverse events are rarely seen in the marketed clinical dosages. In conclusion, 4-AP is easy and safe to use. Slow release 4-AP shows more robust clinical effects and a more beneficial side-effect profile than immediate release 4-AP.
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Affiliation(s)
- Henrik Boye Jensen
- Institute of Regional Health Research, University of Southern Denmark, J.B. Winsløws Vej 19.3, 5000 Odense C, Denmark
| | - Mads Ravnborg
- Department of Neurology, Odense University Hospital, Odense, Denmark
| | - Ulrik Dalgas
- Department of Public Health, Section of Sport Science, Aarhus University, Aarhus, Denmark
| | - Egon Stenager
- Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark
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Bagchi B, Al-Sabi A, Kaza S, Scholz D, O'Leary VB, Dolly JO, Ovsepian SV. Disruption of myelin leads to ectopic expression of K(V)1.1 channels with abnormal conductivity of optic nerve axons in a cuprizone-induced model of demyelination. PLoS One 2014; 9:e87736. [PMID: 24498366 PMCID: PMC3912067 DOI: 10.1371/journal.pone.0087736] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 12/30/2013] [Indexed: 11/19/2022] Open
Abstract
The molecular determinants of abnormal propagation of action potentials along axons and ectopic conductance in demyelinating diseases of the central nervous system, like multiple sclerosis (MS), are poorly defined. Widespread interruption of myelin occurs in several mouse models of demyelination, rendering them useful for research. Herein, considerable myelin loss is shown in the optic nerves of cuprizone-treated demyelinating mice. Immuno-fluorescence confocal analysis of the expression and distribution of voltage-activated K⁺ channels (K(V)1.1 and 1.2 α subunits) revealed their spread from typical juxta-paranodal (JXP) sites to nodes in demyelinated axons, albeit with a disproportionate increase in the level of K(V)1.1 subunit. Functionally, in contrast to monophasic compound action potentials (CAPs) recorded in controls, responses derived from optic nerves of cuprizone-treated mice displayed initial synchronous waveform followed by a dispersed component. Partial restoration of CAPs by broad spectrum (4-aminopyridine) or K(V)1.1-subunit selective (dendrotoxin K) blockers of K⁺ currents suggest enhanced K(V)1.1-mediated conductance in the demyelinated optic nerve. Biophysical profiling of K⁺ currents mediated by recombinant channels comprised of different K(V)1.1 and 1.2 stoichiometries revealed that the enrichment of K(V)1 channels K(V)1.1 subunit endows a decrease in the voltage threshold and accelerates the activation kinetics. Together with the morphometric data, these findings provide important clues to a molecular basis for temporal dispersion of CAPs and reduced excitability of demyelinated optic nerves, which could be of potential relevance to the patho-physiology of MS and related disorders.
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Affiliation(s)
- Bandita Bagchi
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Ahmed Al-Sabi
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Seshu Kaza
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Dimitri Scholz
- Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Valerie B. O'Leary
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - J. Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- * E-mail: (SVO); (JOD)
| | - Saak V. Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- Department of Biotechnology, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Ludwig-Maximilians-Universität München, Zentrum für Neuropathologie, Feodor-Lynen-Str. 23, Munich, Germany
- * E-mail: (SVO); (JOD)
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Ruck T, Bittner S, Simon O, Göbel K, Wiendl H, Schilling M, Meuth S. Long-term effects of dalfampridine in patients with multiple sclerosis. J Neurol Sci 2014; 337:18-24. [DOI: 10.1016/j.jns.2013.11.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/03/2013] [Accepted: 11/08/2013] [Indexed: 10/26/2022]
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Mathiesen HK, Sorensen PS. Prolonged-release fampridine improves walking in a proportion of patients with multiple sclerosis. Expert Rev Neurother 2014; 13:1309-17. [DOI: 10.1586/14737175.2013.859523] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Toosy A, Ciccarelli O, Thompson A. Symptomatic treatment and management of multiple sclerosis. HANDBOOK OF CLINICAL NEUROLOGY 2014; 122:513-562. [PMID: 24507534 DOI: 10.1016/b978-0-444-52001-2.00023-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The range of symptoms which occur in multiple sclerosis (MS) can have disabling functional consequences for patients and lead to significant reductions in their quality of life. MS symptoms can also interact with each other, making their management challenging. Clinical trials aimed at identifying symptomatic therapies have generally been poorly designed and have tended to be underpowered. Therefore, the evidence base for the management of MS symptoms with pharmacologic therapies is not strong and tends to rely upon open-label studies, case reports, and clinical trials with small numbers of patients and poorly validated clinical outcome measures. Recently, there has been a growing interest in the management of MS symptoms with pharmacologic treatments, and better-designed, randomized, double-blind, controlled trials have been reported. This chapter will describe the evidence base predominantly behind the various pharmacologic approaches to the management of MS symptoms, which in most, if not all, cases, requires multidisciplinary input. Drugs routinely recommended for individual symptoms and new therapies, which are currently in the development pipeline, will be reviewed. More interventional therapies related to symptoms that are refractory to pharmacotherapy will also be discussed, where relevant.
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Affiliation(s)
- Ahmed Toosy
- Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK
| | - Olga Ciccarelli
- Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK
| | - Alan Thompson
- Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London, UK.
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Potential therapeutic mechanism of K+ channel block for MS. Mult Scler Relat Disord 2013; 2:270-80. [DOI: 10.1016/j.msard.2013.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 01/07/2013] [Accepted: 01/20/2013] [Indexed: 11/18/2022]
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The diagnosis of chronic inflammatory demyelinating polyneuropathy: a Delphi-method approach. J Neurol 2013; 260:3015-22. [DOI: 10.1007/s00415-013-7100-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/04/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
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49
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Göbel K, Wedell JH, Herrmann AM, Wachsmuth L, Pankratz S, Bittner S, Budde T, Kleinschnitz C, Faber C, Wiendl H, Meuth SG. 4-Aminopyridine ameliorates mobility but not disease course in an animal model of multiple sclerosis. Exp Neurol 2013; 248:62-71. [PMID: 23748135 DOI: 10.1016/j.expneurol.2013.05.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 05/22/2013] [Accepted: 05/25/2013] [Indexed: 01/21/2023]
Abstract
Neuropathological changes following demyelination in multiple sclerosis (MS) lead to a reorganization of axolemmal channels that causes conduction changes including conduction failure. Pharmacological modulation of voltage-sensitive potassium channels (K(V)) has been found to improve conduction in experimentally induced demyelination and produces symptomatic improvement in MS patients. Here we used an animal model of autoimmune inflammatory neurodegeneration, namely experimental autoimmune encephalomyelitis (EAE), to test the influence of the K(V)-inhibitor 4-aminopyridine (4-AP) on various disease and immune parameters as well as mobility in MOG₃₅₋₅₅ immunized C57Bl/6 mice. We challenged the hypothesis that 4-AP exerts relevant immunomodulatory or neuroprotective properties. Neither prophylactic nor therapeutic treatment with 4-AP altered disease incidence or disease course of EAE. Histopathological signs of demyelination and neuronal damage as well as MRI imaging of brain volume changes were unaltered. While application of 4-AP significantly reduced the standing outward current of stimulated CD4(+) T cells compared to controls, it failed to impact intracellular calcium concentrations in these cells. Compatibly, KV channel inhibition neither influenced CD4(+) T cell effector functions (proliferation, IL17 or IFNγ production). Importantly however, despite equal disease severity scores 4-AP treated animals showed improved mobility as assessed by 2 independent methods, 1) foot print and 2) rotarod analysis (0.332 ± 0.03, n=7 versus 0.399 ± 0.08, n=14, p<0.001, respectively). Our data suggest that 4-AP while having no apparent immunomodulatory or direct neuroprotective effects, significantly ameliorates conduction abnormalities thereby improving gait and coordination. Improvement of mobility in this experimental model supports trial data and clinical experience with 4-AP in the symptomatic treatment of MS.
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Affiliation(s)
- Kerstin Göbel
- University of Muenster, Department of Neurology, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany.
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Abstract
Aminopyridines are members of a family of monoamino and diamino derivatives of pyridine, and their principal mechanism of action is dose-dependent blockade of voltage-gated potassium channels, in particular, fast voltage-gated potassium channels. To date, only 2 main broad-spectrum potassium channel blockers, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP), have been used as investigational new drugs in various neurological diseases. More recently, licensed versions of these compounds including dalfampridine extended release (Fampyra, Biogen Idec) for the improvement of walking in adult patients with multiple sclerosis, and amifampridine (Firdapse, Biomarin Europe Ltd) for the treatment of Lambert-Eaton myasthenic syndrome have been released, and the costs associated with using these new products highlights the importance of evaluating the clinically meaningful treatment effects of these drugs.The current review summarizes the evidence of aminopyridine use in neurological conditions and in particular presents a systematic review of all randomized trials of 3,4-DAP in Lambert-Eaton myasthenic syndrome to determine the efficacy of this treatment using meta-analysis of clinical and electrophysiological end points.
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