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Newman BT, Jacokes Z, Venkadesh S, Webb SJ, Kleinhans NM, McPartland JC, Druzgal TJ, Pelphrey KA, Van Horn JD. Conduction velocity, G-ratio, and extracellular water as microstructural characteristics of autism spectrum disorder. PLoS One 2024; 19:e0301964. [PMID: 38630783 PMCID: PMC11023574 DOI: 10.1371/journal.pone.0301964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 03/26/2024] [Indexed: 04/19/2024] Open
Abstract
The neuronal differences contributing to the etiology of autism spectrum disorder (ASD) are still not well defined. Previous studies have suggested that myelin and axons are disrupted during development in ASD. By combining structural and diffusion MRI techniques, myelin and axons can be assessed using extracellular water, aggregate g-ratio, and a new approach to calculating axonal conduction velocity termed aggregate conduction velocity, which is related to the capacity of the axon to carry information. In this study, several innovative cellular microstructural methods, as measured from magnetic resonance imaging (MRI), are combined to characterize differences between ASD and typically developing adolescent participants in a large cohort. We first examine the relationship between each metric, including microstructural measurements of axonal and intracellular diffusion and the T1w/T2w ratio. We then demonstrate the sensitivity of these metrics by characterizing differences between ASD and neurotypical participants, finding widespread increases in extracellular water in the cortex and decreases in aggregate g-ratio and aggregate conduction velocity throughout the cortex, subcortex, and white matter skeleton. We finally provide evidence that these microstructural differences are associated with higher scores on the Social Communication Questionnaire (SCQ) a commonly used diagnostic tool to assess ASD. This study is the first to reveal that ASD involves MRI-measurable in vivo differences of myelin and axonal development with implications for neuronal and behavioral function. We also introduce a novel formulation for calculating aggregate conduction velocity, that is highly sensitive to these changes. We conclude that ASD may be characterized by otherwise intact structural connectivity but that functional connectivity may be attenuated by network properties affecting neural transmission speed. This effect may explain the putative reliance on local connectivity in contrast to more distal connectivity observed in ASD.
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Affiliation(s)
- Benjamin T. Newman
- Department of Psychology, University of Virginia, Charlottesville, VA, United States of America
- UVA School of Medicine, University of Virginia, Charlottesville, VA, United States of America
| | - Zachary Jacokes
- School of Data Science, University of Virginia, Elson Building, Charlottesville, VA, United States of America
| | - Siva Venkadesh
- Department of Psychology, University of Virginia, Charlottesville, VA, United States of America
| | - Sara J. Webb
- Department of Psychiatry and Behavioral Science, University of Washington, Seattle WA, United States of America
- Seattle Children’s Research Institute, Seattle WA, United States of America
| | - Natalia M. Kleinhans
- Department of Radiology, Integrated Brain Imaging Center, University of Washington, Seattle, WA, United States of America
| | - James C. McPartland
- Yale Child Study Center, New Haven, CT, United States of America
- Yale Center for Brain and Mind Health, New Haven, CT, United States of America
| | - T. Jason Druzgal
- UVA School of Medicine, University of Virginia, Charlottesville, VA, United States of America
| | - Kevin A. Pelphrey
- UVA School of Medicine, University of Virginia, Charlottesville, VA, United States of America
| | - John Darrell Van Horn
- Department of Psychology, University of Virginia, Charlottesville, VA, United States of America
- School of Data Science, University of Virginia, Elson Building, Charlottesville, VA, United States of America
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Macedo MB, Cunha EO, Reis AD, Machado MS, de Campos D, Malysz T, Dallegrave E. Morphometric Evaluation of the Recurrent Laryngeal Nerve of Wistar Rats Exposed to Pesticides. J Voice 2024; 38:264-272. [PMID: 34782225 DOI: 10.1016/j.jvoice.2021.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/09/2021] [Accepted: 09/23/2021] [Indexed: 10/19/2022]
Abstract
The literature has been shown that exposition by inhalation to chemical compounds can cause vocal disorders and dysphagia in humans, in addition to other symptoms that are manifested according to the type, concentration and duration of exposure to the substance. Cypermethrin and dichlorvos are pesticides widely used in agriculture, public health, veterinary, and home environments. Despite the scientific evidence that cypermethrin and dichlorvos can cause neurodegenerative damage and motor alterations, there are no studies evaluating the toxic effects of these pesticides on the morphology of structures responsible for vocal mobility, especially to the Recurrent Laryngeal Nerve (RLN). Considering the association between vocal disorders in humans and variations in RLN and morphometry, the aim of this study was to evaluate the possible alterations in the microstructure of RLN secondary to subchronic exposure to cypermethrin (pyrethroid) and dichlorvos (organophosphate) in Wistar rats. The experimental protocol (approved by CEUA-UFCSPA: 321/15 and 323/15) consisted of 15 male Wistar rats, allocated in 3 groups: Control (n = 5, exposed to water), Cypermethrin (n = 5, exposed to cypermethrin - 1/10 of the inhalation median lethal concentration [LC50] - 0.25 mg/L) and dichlorvos (n = 5, exposed to dichlorvos - 1/10 of the LC50 - 1.5 mg/L). Inhalation exposure was performed for 4 hours, 5 times per week, for 6 weeks. The nerves were collected, histologically processed and analyzed using morphometric parameters measured using ZEN 2.6 (Zeiss - Germany). The cypermethrin and dichlorvos groups showed significant changes (P < 0.001, ANOVA) in the g-ratio and in the thickness of the myelin sheath of the RLN when compared to the control animals, however, none of the other parameters evaluated showed statistically significant differences. These findings indicate that repeated inhalation exposure to commercial products of cypermethrin and dichlorvos is able to modify the structure of the RLN and possibly generating vocal changes and / or dysphagia.
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Affiliation(s)
- Mateus Belmonte Macedo
- Graduate Program in Pathology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Laboratory of Research in Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Eduarda Oliveira Cunha
- Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Laboratory of Research in Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Aléxia Dos Reis
- Graduate Program in Pathology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Laboratory of Research in Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Márcia Salgado Machado
- Department of Speech Therapy and Audiology, University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Laboratory of Research in Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil
| | - Deivis de Campos
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Department of Life Sciences, University of Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS, Brazil; Graduate Program in Health Promotion, University of Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS, Brazil
| | - Taís Malysz
- Graduate Program in Neurosciences, Basic Health Sciences Institute, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Eliane Dallegrave
- Graduate Program in Pathology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Department of Pharmacosciences, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil; Laboratory of Research in Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, RS, Brazil.
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Newman BT, Jacokes Z, Venkadesh S, Webb SJ, Kleinhans NM, McPartland JC, Druzgal TJ, Pelphrey KA, Van Horn JD. Conduction Velocity, G-ratio, and Extracellular Water as Microstructural Characteristics of Autism Spectrum Disorder. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.23.550166. [PMID: 37546913 PMCID: PMC10402058 DOI: 10.1101/2023.07.23.550166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The neuronal differences contributing to the etiology of autism spectrum disorder (ASD) are still not well defined. Previous studies have suggested that myelin and axons are disrupted during development in ASD. By combining structural and diffusion MRI techniques, myelin and axons can be assessed using extracellular water, aggregate g-ratio, and a novel metric termed aggregate conduction velocity, which is related to the capacity of the axon to carry information. In this study, several innovative cellular microstructural methods, as measured from magnetic resonance imaging (MRI), are combined to characterize differences between ASD and typically developing adolescent participants in a large cohort. We first examine the relationship between each metric, including microstructural measurements of axonal and intracellular diffusion and the T1w/T2w ratio. We then demonstrate the sensitivity of these metrics by characterizing differences between ASD and neurotypical participants, finding widespread increases in extracellular water in the cortex and decreases in aggregate g-ratio and aggregate conduction velocity throughout the cortex, subcortex, and white matter skeleton. We finally provide evidence that these microstructural differences are associated with higher scores on the Social Communication Questionnaire (SCQ) a commonly used diagnostic tool to assess ASD. This study is the first to reveal that ASD involves MRI-measurable in vivo differences of myelin and axonal development with implications for neuronal and behavioral function. We also introduce a novel neuroimaging metric, aggregate conduction velocity, that is highly sensitive to these changes. We conclude that ASD may be characterized by otherwise intact structural connectivity but that functional connectivity may be attenuated by network properties affecting neural transmission speed. This effect may explain the putative reliance on local connectivity in contrast to more distal connectivity observed in ASD.
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Affiliation(s)
- Benjamin T. Newman
- Department of Psychology, University of Virginia, Gilmer Hall, Charlottesville, VA 22903
- UVA School of Medicine, University of Virginia, 560 Ray Hunt Drive, Charlottesville, VA 22903
| | - Zachary Jacokes
- School of Data Science, University of Virginia, Elson Building, Charlottesville, VA 22903
| | - Siva Venkadesh
- Department of Psychology, University of Virginia, Gilmer Hall, Charlottesville, VA 22903
| | - Sara J. Webb
- Department of Psychiatry and Behavioral Science, University of Washington, Seattle WA USA 98195
- Seattle Children’s Research Institute, 1920 Terry Ave, Building Cure-03, Seattle WA 98101
| | - Natalia M. Kleinhans
- Department of Radiology, Integrated Brain Imaging Center, University of Washington, 1959 NE Pacific St Seattle, WA 98195
| | - James C. McPartland
- Yale Child Study Center, 230 South Frontage Road, New Haven, CT 06520
- Yale Center for Brain and Mind Health, 40 Temple Street, Suite 6A, New Haven, CT, 06520
| | - T. Jason Druzgal
- UVA School of Medicine, University of Virginia, 560 Ray Hunt Drive, Charlottesville, VA 22903
| | - Kevin A. Pelphrey
- UVA School of Medicine, University of Virginia, 560 Ray Hunt Drive, Charlottesville, VA 22903
| | - John Darrell Van Horn
- Department of Psychology, University of Virginia, Gilmer Hall, Charlottesville, VA 22903
- School of Data Science, University of Virginia, Elson Building, Charlottesville, VA 22903
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Anderson SR, Burg E, Suveg L, Litovsky RY. Review of Binaural Processing With Asymmetrical Hearing Outcomes in Patients With Bilateral Cochlear Implants. Trends Hear 2024; 28:23312165241229880. [PMID: 38545645 PMCID: PMC10976506 DOI: 10.1177/23312165241229880] [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: 04/25/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 04/01/2024] Open
Abstract
Bilateral cochlear implants (BiCIs) result in several benefits, including improvements in speech understanding in noise and sound source localization. However, the benefit bilateral implants provide among recipients varies considerably across individuals. Here we consider one of the reasons for this variability: difference in hearing function between the two ears, that is, interaural asymmetry. Thus far, investigations of interaural asymmetry have been highly specialized within various research areas. The goal of this review is to integrate these studies in one place, motivating future research in the area of interaural asymmetry. We first consider bottom-up processing, where binaural cues are represented using excitation-inhibition of signals from the left ear and right ear, varying with the location of the sound in space, and represented by the lateral superior olive in the auditory brainstem. We then consider top-down processing via predictive coding, which assumes that perception stems from expectations based on context and prior sensory experience, represented by cascading series of cortical circuits. An internal, perceptual model is maintained and updated in light of incoming sensory input. Together, we hope that this amalgamation of physiological, behavioral, and modeling studies will help bridge gaps in the field of binaural hearing and promote a clearer understanding of the implications of interaural asymmetry for future research on optimal patient interventions.
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Affiliation(s)
- Sean R. Anderson
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical School, Aurora, CO, USA
| | - Emily Burg
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lukas Suveg
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Ruth Y. Litovsky
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, USA
- Department of Surgery, Division of Otolaryngology, University of Wisconsin-Madison, Madison, WI, USA
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Zhang Z, Wang W, Huang X, Liu G. Distributed loss-amplification modeling for the mid-infrared signal propagating in the myelinated and demyelinated nerve. APPLIED OPTICS 2023; 62:8606-8613. [PMID: 38037977 DOI: 10.1364/ao.503485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/20/2023] [Indexed: 12/02/2023]
Abstract
The terahertz (THz) to infrared (IR) neural signal model is a potential mechanism for explaining neural communication. Myelinated neurons could be a lossy dielectric waveguide that can propagate these THz-IR neural signals. We propose an electromagnetic loss-amplification model to describe the propagation characteristics of mid-IR signals on myelinated neurons. During transmission with loss and amplification, neural signal intensity can be consistently maintained at 15.9 pW in bands 55 to 75 THz. This phenomenon becomes more pronounced as the number of myelin sheaths increases. However, escalated degrees of demyelination result in a reduction of signal intensity from 15.9 to 10 pW. This phenomenon eventually disrupts the process of loss amplification, consequently impeding the transmission of the signal. These results may contribute to a deeper understanding of mid-IR signal propagation mechanisms in myelinated nerves and studies of diseases associated with demyelination.
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Berman JI, Bloy L, Blaskey L, Jackel CR, Miller JS, Ross J, Edgar JC, Roberts TPL. Contributions to auditory system conduction velocity: insights with multi-modal neuroimaging and machine learning in children with ASD and XYY syndrome. Front Psychiatry 2023; 14:1057221. [PMID: 37252131 PMCID: PMC10219612 DOI: 10.3389/fpsyt.2023.1057221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 04/17/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction The M50 electrophysiological auditory evoked response time can be measured at the superior temporal gyrus with magnetoencephalography (MEG) and its latency is related to the conduction velocity of auditory input passing from ear to auditory cortex. In children with autism spectrum disorder (ASD) and certain genetic disorders such as XYY syndrome, the auditory M50 latency has been observed to be elongated (slowed). Methods The goal of this study is to use neuroimaging (diffusion MR and GABA MRS) measures to predict auditory conduction velocity in typically developing (TD) children and children with autism ASD and XYY syndrome. Results Non-linear TD support vector regression modeling methods accounted for considerably more M50 latency variance than linear models, likely due to the non-linear dependence on neuroimaging factors such as GABA MRS. While SVR models accounted for ~80% of the M50 latency variance in TD and the genetically homogenous XYY syndrome, a similar approach only accounted for ~20% of the M50 latency variance in ASD, implicating the insufficiency of diffusion MR, GABA MRS, and age factors alone. Biologically based stratification of ASD was performed by assessing the conformance of the ASD population to the TD SVR model and identifying a sub-population of children with unexpectedly long M50 latency. Discussion Multimodal integration of neuroimaging data can help build a mechanistic understanding of brain connectivity. The unexplained M50 latency variance in ASD motivates future hypothesis generation and testing of other contributing biological factors.
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Affiliation(s)
- Jeffrey I. Berman
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Luke Bloy
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Lisa Blaskey
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Center for Autism Research, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Carissa R. Jackel
- Division of Developmental and Behavioral Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Judith S. Miller
- Center for Autism Research, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Judith Ross
- Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA, United States
- Nemours Children's Hospital-Delaware, Wilmington, DE, United States
| | - J. Christopher Edgar
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Timothy P. L. Roberts
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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Niimi Y, Gomez-Tames J, Wasaka T, Hirata A. Selective stimulation of nociceptive small fibers during intraepidermal electrical stimulation: Experiment and computational analysis. Front Neurosci 2023; 16:1045942. [PMID: 36711140 PMCID: PMC9880216 DOI: 10.3389/fnins.2022.1045942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023] Open
Abstract
Electrical stimulation of skin nociceptors is gaining attention in pain research and peripheral neuropathy diagnosis. However, the optimal parameters for selective stimulation are still difficult to determine because they require simultaneous characterization of the electrical response of small fibers (Aδ- and C-fibers). In this study, we measured the in vivo electrical threshold responses of small fibers to train-pulse stimulation in humans for the first time. We also examined selective stimulation via a computational model, which combines electrical analysis, and terminal fiber and synaptic models, including the first cutaneous pain C-fiber model. Selective stimulation of small fibers is performed by injecting train-pulse stimulation via coaxial electrodes with an intraepidermal needle tip at varying pulse counts and frequencies. The activation Aδ- or C-fibers was discriminated from the differences in reaction time. Aδ-fiber elicited a pinpricking sensation with a mean reaction time of 0.522 s, and C-fiber elicited a tingling sensation or slight burning itch with a mean reaction time of 1.243 s. The implemented multiscale electrical model investigates synaptic effects while considering stimulation waveform characteristics. Experimental results showed that perception thresholds decreased with the number of consecutive pulses and frequency up to convergence (five pulses or 70 Hz) during the selective stimulation of Aδ- and C-fibers. Considering the synaptic properties, the optimal stimulus conditions for selective stimulation of Aδ- vs. C-fibers were train of at least four pulses and a frequency of 40-70 Hz at a pulse width of 1 ms. The experimental results were modeled with high fidelity by incorporating temporal synaptic effects into the computational model. Numerical analysis revealed terminal axon thickness to be the most important biophysical factor affecting threshold variability. The computational model can be used to estimate perception thresholds while understanding the mechanisms underlying the selective stimulation of small fibers. The parameters derived here are important in exploring selective stimulation between Aδ- and C-fibers for diagnosing neuropathies.
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Affiliation(s)
- Yuki Niimi
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Jose Gomez-Tames
- Center for Frontier Medical Engineering, Chiba University, Chiba, Japan
| | - Toshiaki Wasaka
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan,*Correspondence: Akimasa Hirata,
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8
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Genc S, Raven EP, Drakesmith M, Blakemore SJ, Jones DK. Novel insights into axon diameter and myelin content in late childhood and adolescence. Cereb Cortex 2023; 33:6435-6448. [PMID: 36610731 PMCID: PMC10183755 DOI: 10.1093/cercor/bhac515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 01/09/2023] Open
Abstract
White matter microstructural development in late childhood and adolescence is driven predominantly by increasing axon density and myelin thickness. Ex vivo studies suggest that the increase in axon diameter drives developmental increases in axon density observed with pubertal onset. In this cross-sectional study, 50 typically developing participants aged 8-18 years were scanned using an ultra-strong gradient magnetic resonance imaging scanner. Microstructural properties, including apparent axon diameter $({d}_a)$, myelin content, and g-ratio, were estimated in regions of the corpus callosum. We observed age-related differences in ${d}_a$, myelin content, and g-ratio. In early puberty, males had larger ${d}_a$ in the splenium and lower myelin content in the genu and body of the corpus callosum, compared with females. Overall, this work provides novel insights into developmental, pubertal, and cognitive correlates of individual differences in apparent axon diameter and myelin content in the developing human brain.
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Affiliation(s)
- Sila Genc
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Rd, Cardiff CF24 4HQ, United Kingdom
| | - Erika P Raven
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Rd, Cardiff CF24 4HQ, United Kingdom.,Department of Radiology, New York University School of Medicine, 550 1st Ave., New York, NY 10016, United States
| | - Mark Drakesmith
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Rd, Cardiff CF24 4HQ, United Kingdom
| | - Sarah-Jayne Blakemore
- Department of Psychology, University of Cambridge, Downing Pl, Cambridge CB2 3EB, United Kingdom
| | - Derek K Jones
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Rd, Cardiff CF24 4HQ, United Kingdom
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Mayer J, Krug C, Saller M, Feuchtinger A, Giunta R, Volkmer E, Holzbach T. Hypoxic pre-conditioned adipose-derived stem/progenitor cells embedded in fibrin conduits promote peripheral nerve regeneration in a sciatic nerve graft model. Neural Regen Res 2023; 18:652-656. [DOI: 10.4103/1673-5374.346464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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10
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Sessler CD, Zhou Y, Wang W, Hartley ND, Fu Z, Graykowski D, Sheng M, Wang X, Liu J. Optogenetic polymerization and assembly of electrically functional polymers for modulation of single-neuron excitability. SCIENCE ADVANCES 2022; 8:eade1136. [PMID: 36475786 PMCID: PMC9728971 DOI: 10.1126/sciadv.ade1136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 10/28/2022] [Indexed: 06/17/2023]
Abstract
Ionic conductivity and membrane capacitance are two foundational parameters that govern neuron excitability. Conventional optogenetics has emerged as a powerful tool to temporarily manipulate membrane ionic conductivity in intact biological systems. However, no analogous method exists for precisely manipulating cell membrane capacitance to enable long-lasting modulation of neuronal excitability. Genetically targetable chemical assembly of conductive and insulating polymers can modulate cell membrane capacitance, but further development of this technique has been hindered by poor spatiotemporal control of the polymer deposition and cytotoxicity from the widely diffused peroxide. We address these issues by harnessing genetically targetable photosensitizer proteins to assemble electrically functional polymers in neurons with precise spatiotemporal control. Using whole-cell patch-clamp recordings, we demonstrate that this optogenetic polymerization can achieve stepwise modulation of both neuron membrane capacitance and intrinsic excitability. Furthermore, cytotoxicity can be limited by controlling light exposure, demonstrating a promising new method for precisely modulating cell excitability.
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Affiliation(s)
- Chanan D. Sessler
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Yiming Zhou
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Wenbo Wang
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Nolan D. Hartley
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Zhanyan Fu
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - David Graykowski
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Morgan Sheng
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Xiao Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Jia Liu
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
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11
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Zhou R, Han B, Nowak R, Lu Y, Heller E, Xia C, Chishti AH, Fowler VM, Zhuang X. Proteomic and functional analyses of the periodic membrane skeleton in neurons. Nat Commun 2022; 13:3196. [PMID: 35680881 PMCID: PMC9184744 DOI: 10.1038/s41467-022-30720-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 05/09/2022] [Indexed: 12/29/2022] Open
Abstract
Actin, spectrin, and associated molecules form a membrane-associated periodic skeleton (MPS) in neurons. The molecular composition and functions of the MPS remain incompletely understood. Here, using co-immunoprecipitation and mass spectrometry, we identified hundreds of potential candidate MPS-interacting proteins that span diverse functional categories. We examined representative proteins in several of these categories using super-resolution imaging, including previously unknown MPS structural components, as well as motor proteins, cell adhesion molecules, ion channels, and signaling proteins, and observed periodic distributions characteristic of the MPS along the neurites for ~20 proteins. Genetic perturbations of the MPS and its interacting proteins further suggested functional roles of the MPS in axon-axon and axon-dendrite interactions and in axon diameter regulation, and implicated the involvement of MPS interactions with cell adhesion molecules and non-muscle myosin in these roles. These results provide insights into the interactome of the MPS and suggest previously unknown functions of the MPS in neurons.
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Affiliation(s)
- Ruobo Zhou
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Boran Han
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Roberta Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
| | - Yunzhe Lu
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Evan Heller
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Chenglong Xia
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Athar H Chishti
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
- Department of Biological Sciences, The University of Delaware, Newark, DE, 19716, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
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12
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Krause Neto W, Gama EF, Silva WDA, de Oliveira TVA, Vilas Boas AEDS, Ciena AP, Anaruma CA, Caperuto ÉC. The sciatic and radial nerves seem to adapt similarly to different ladder-based resistance training protocols. Exp Brain Res 2022; 240:887-896. [DOI: 10.1007/s00221-021-06295-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/16/2021] [Indexed: 11/25/2022]
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13
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Lizarraga‐Valderrama LR, Ronchi G, Nigmatullin R, Fregnan F, Basnett P, Paxinou A, Geuna S, Roy I. Preclinical study of peripheral nerve regeneration using nerve guidance conduits based on polyhydroxyalkanaotes. Bioeng Transl Med 2021; 6:e10223. [PMID: 34589600 PMCID: PMC8459605 DOI: 10.1002/btm2.10223] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 03/09/2021] [Accepted: 03/14/2021] [Indexed: 02/01/2023] Open
Abstract
Nerve guidance conduits (NGCs) are used as an alternative to the "gold standard" nerve autografting, preventing the need for surgical intervention required to harvest autologous nerves. However, the regeneration outcomes achieved with the current NGCs are only comparable with autografting when the gap is short (less than 10 mm). In the present study, we have developed NGCs made from a blend of polyhydroxyalkanoates, a family of natural resorbable polymers. Hollow NGCs made from a 75:25 poly(3-hydroxyoctanoate)/poly(3-hydroxybutyrate) blend (PHA-NGCs) were manufactured using dip-molding. These PHA-NGCs showed appropriate flexibility for peripheral nerve regeneration. In vitro cell studies performed using RT4-D6P2T rat Schwann cell line confirmed that the material is capable of sustaining cell proliferation and adhesion. PHA-NGCs were then implanted in vivo to repair 10 mm gaps of the median nerve of female Wistar rats for 12 weeks. Functional evaluation of the regenerated nerve using the grasping test showed that PHA-NGCs displayed similar motor recovery as the autograft, starting from week 7. Additionally, nerve cross-sectional area, density and number of myelinated cells, as well as axon diameter, fiber diameter, myelin thickness and g-ratio obtained using the PHA-NGCs were found comparable to an autograft. This preclinical data confirmed that the PHA-NGCs are indeed highly promising candidates for peripheral nerve regeneration.
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Affiliation(s)
- Lorena R. Lizarraga‐Valderrama
- School of Life Sciences, College of Liberal Arts and SciencesUniversity of WestminsterLondonUK
- School of Life Sciences, Queen's Medical CentreUniversity of NottinghamNottinghamUK
| | - Giulia Ronchi
- Department of Clinical and Biological SciencesUniversity of TurinTurinItaly
- Neuroscience Institute of the Cavalieri Ottolenghi Foundation (NICO)University of TurinTurinItaly
| | - Rinat Nigmatullin
- School of Life Sciences, College of Liberal Arts and SciencesUniversity of WestminsterLondonUK
- Bristol Composites Institute (ACCIS)University of BristolBristolUK
| | - Federica Fregnan
- Department of Clinical and Biological SciencesUniversity of TurinTurinItaly
- Neuroscience Institute of the Cavalieri Ottolenghi Foundation (NICO)University of TurinTurinItaly
| | - Pooja Basnett
- School of Life Sciences, College of Liberal Arts and SciencesUniversity of WestminsterLondonUK
| | - Alexandra Paxinou
- School of Life Sciences, College of Liberal Arts and SciencesUniversity of WestminsterLondonUK
| | - Stefano Geuna
- Department of Clinical and Biological SciencesUniversity of TurinTurinItaly
- Neuroscience Institute of the Cavalieri Ottolenghi Foundation (NICO)University of TurinTurinItaly
| | - Ipsita Roy
- Department of Materials Science and Engineering, Faculty of EngineeringUniversity of SheffieldSheffieldUK
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14
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CSF Diagnostics: A Potentially Valuable Tool in Neurodegenerative and Inflammatory Disorders Involving Motor Neurons: A Review. Diagnostics (Basel) 2021; 11:diagnostics11091522. [PMID: 34573864 PMCID: PMC8470638 DOI: 10.3390/diagnostics11091522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/10/2021] [Accepted: 08/19/2021] [Indexed: 11/16/2022] Open
Abstract
Cerebrospinal fluid (CSF) diagnostics has emerged as a valid tool for a variety of neurological diseases. However, CSF diagnostics has been playing a subordinate role in the diagnosis of many neurological conditions. Thus, in the multitude of neuromuscular diseases in which motor neurons are affected, a CSF sample is rarely taken routinely. However, CSF diagnostics has the potential to specify the diagnosis and monitor the treatment of neuromuscular disorders. In this review, we therefore focused on a variety of neuromuscular diseases, among them amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and spinal muscular atrophy (SMA), for which CSF diagnostics has emerged as a promising option for determining the disease itself and its progression. We focus on potentially valuable biomarkers among different disorders, such as neurofilaments, cytokines, other proteins, and lipids to determine their suitability, differentiating between different neurological disorders and their potential to determine early disease onset, disease progression, and treatment outcome. We further recommend novel approaches, e.g., the use of mass spectrometry as a promising alternative techniques to standard ELISA assays, potentially enhancing biomarker significance in clinical applications.
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15
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Neto WK, Gama EF, de Assis Silva W, de Oliveira TVA, Dos Santos Vilas Boas AE, Ciena AP, Anaruma CA, Caperuto ÉC. Ladder-based resistance training elicited similar ultrastructural adjustments in forelimb and hindlimb peripheral nerves of young adult Wistar rats. Exp Brain Res 2021; 239:2583-2592. [PMID: 34191117 DOI: 10.1007/s00221-021-06156-y] [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: 04/14/2021] [Accepted: 06/19/2021] [Indexed: 12/22/2022]
Abstract
To analyze the morphological response induced by high-volume, high-intensity ladder-based resistance training (LRT) on the ultrastructure of the radial (forelimb) and sciatic (hindlimb) nerves of adults Wistar rats. Twenty rats were equally distributed into groups: sedentary (SED) and LRT. After the rodents were subjected to the maximum load (ML) carrying test, the LRT group performed 6-8 progressive climbs (2 × 50% ML, 2 × 75% ML, 2 × 100% ML, and 2 × 100% ML + 30 g) three times per week. After 8 weeks, the radial and sciatic nerves were removed and prepared for transmission electron microscopy. In the radial nerve, myelinated axons cross-sectional area (CSA), unmyelinated axons CSA, myelin sheath thickness, and Schwann cells nuclei area were statistically larger in the LRT group than SED (p < 0.05). Also, the number of microtubules and neurofilaments per field were statistically higher in the LRT group than in SED (p < 0.01). For sciatic nerve, myelinated fibers CSA, unmyelinated axons CSA, myelin sheath thickness, Schwann cells nuclei area, and the number of neurofilaments per field were statistically larger in the LRT group compared to the SED group (p < 0.05). LRT with high-volume and high-intensity effectively induce similar changes in adult Wistar rats' radial and sciatic nerves' ultrastructure.
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Affiliation(s)
- Walter Krause Neto
- Department of Physical Education, Laboratory of Morphoquantitative Studies and Immunohistochemistry, São Judas Tadeu University, Rua Taquari, 546-Mooca Unit, P. O. Box 03166-000, São Paulo, SP, Brazil.
| | - Eliane Florencio Gama
- Department of Morphology, Faculty of Medical Sciences, Santa Casa de São Paulo, São Paulo, SP, Brazil
| | - Wellington de Assis Silva
- Department of Physical Education, Laboratory of Morphoquantitative Studies and Immunohistochemistry, São Judas Tadeu University, Rua Taquari, 546-Mooca Unit, P. O. Box 03166-000, São Paulo, SP, Brazil
| | - Tony Vinicius Apolinário de Oliveira
- Department of Physical Education, Laboratory of Morphoquantitative Studies and Immunohistochemistry, São Judas Tadeu University, Rua Taquari, 546-Mooca Unit, P. O. Box 03166-000, São Paulo, SP, Brazil
| | - Alan Esaú Dos Santos Vilas Boas
- Department of Physical Education, Laboratory of Morphoquantitative Studies and Immunohistochemistry, São Judas Tadeu University, Rua Taquari, 546-Mooca Unit, P. O. Box 03166-000, São Paulo, SP, Brazil
| | - Adriano Polican Ciena
- Department of Physical Education, Laboratory of Morphology and Physical Activity, São Paulo State University "Júlio de Mesquita Filho", Rio Claro, SP, Brazil
| | - Carlos Alberto Anaruma
- Department of Physical Education, Laboratory of Morphology and Physical Activity, São Paulo State University "Júlio de Mesquita Filho", Rio Claro, SP, Brazil
| | - Érico Chagas Caperuto
- Depatment of Physical Education, Laboratory of Human Movement, São Judas Tadeu University, São Paulo, SP, Brazil
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16
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Tanaka T, Ohno N, Osanai Y, Saitoh S, Thai TQ, Nishimura K, Shinjo T, Takemura S, Tatsumi K, Wanaka A. Large-scale electron microscopic volume imaging of interfascicular oligodendrocytes in the mouse corpus callosum. Glia 2021; 69:2488-2502. [PMID: 34165804 DOI: 10.1002/glia.24055] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 12/16/2022]
Abstract
Single oligodendrocytes produce myelin sheaths around multiple axons in the central nervous system. Interfascicular oligodendrocytes (IOs) facilitate nerve conduction, but their detailed morphologies remain largely unknown. In the present study, we three-dimensionally reconstructed IOs in the corpus callosum of adult mouse using serial block face scanning electron microscopy. The cell bodies of IOs were morphologically polarized and extended thick processes from the cytoplasm-rich part of the cell. Processes originating from the cell body of each IO can be classified into two types: one myelinates an axon without branching, while the other type branches and each branch myelinates a distinct axon. Myelin sheaths originating from a particular IO have biased thicknesses, wrapping axons of a limited range of diameters. Consistent with this finding, IOs transduced and visualized with a rabies viral vector expressing GFP showed statistically significant variation in their myelination patterns. We further reconstructed the sheath immediately adjacent to that derived from each of the analyzed IOs; the thicknesses of the pair of sheaths were significantly correlated despite emanating from different IOs. These results suggest that a single axon could regulate myelin sheath thicknesses, even if the sheaths are derived from distinct IOs. Collectively, our results indicate that the IOs have their own myelin profiles defined by myelin thickness and axonal diameter although axons may regulate thickness of myelin sheath.
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Affiliation(s)
- Tatsuhide Tanaka
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke, Japan
| | - Yasuyuki Osanai
- Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke, Japan.,Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Japan
| | - Sei Saitoh
- Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan.,Department of Anatomy II and Cell Biology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Truc Quynh Thai
- Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke, Japan
| | - Kazuya Nishimura
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
| | - Takeaki Shinjo
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
| | - Shoko Takemura
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
| | - Kouko Tatsumi
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
| | - Akio Wanaka
- Department of Anatomy and Neuroscience, Nara Medical University, Kashihara, Japan
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17
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Turner S, Lazarus R, Marion D, Main KL. Molecular and Diffusion Tensor Imaging Biomarkers of Traumatic Brain Injury: Principles for Investigation and Integration. J Neurotrauma 2021; 38:1762-1782. [PMID: 33446015 DOI: 10.1089/neu.2020.7259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The last 20 years have seen the advent of new technologies that enhance the diagnosis and prognosis of traumatic brain injury (TBI). There is recognition that TBI affects the brain beyond initial injury, in some cases inciting a progressive neuropathology that leads to chronic impairments. Medical researchers are now searching for biomarkers to detect and monitor this condition. Perhaps the most promising developments are in the biomolecular and neuroimaging domains. Molecular assays can identify proteins indicative of neuronal injury and/or degeneration. Diffusion imaging now allows sensitive evaluations of the brain's cellular microstructure. As the pace of discovery accelerates, it is important to survey the research landscape and identify promising avenues of investigation. In this review, we discuss the potential of molecular and diffusion tensor imaging (DTI) biomarkers in TBI research. Integration of these technologies could advance models of disease prognosis, ultimately improving care. To date, however, few studies have explored relationships between molecular and DTI variables in patients with TBI. Here, we provide a short primer on each technology, review the latest research, and discuss how these biomarkers may be incorporated in future studies.
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Affiliation(s)
- Stephanie Turner
- Defense and Veterans Brain Injury Center, Silver Spring, Maryland, USA.,General Dynamics Information Technology, Falls Church, Virginia, USA
| | - Rachel Lazarus
- Defense and Veterans Brain Injury Center, Silver Spring, Maryland, USA.,General Dynamics Information Technology, Falls Church, Virginia, USA
| | - Donald Marion
- Defense and Veterans Brain Injury Center, Silver Spring, Maryland, USA.,General Dynamics Information Technology, Falls Church, Virginia, USA
| | - Keith L Main
- Defense and Veterans Brain Injury Center, Silver Spring, Maryland, USA.,General Dynamics Information Technology, Falls Church, Virginia, USA
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18
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Bartmeyer PM, Biscola NP, Havton LA. A shape-adjusted ellipse approach corrects for varied axonal dispersion angles and myelination in primate nerve roots. Sci Rep 2021; 11:3150. [PMID: 33542368 PMCID: PMC7862494 DOI: 10.1038/s41598-021-82575-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/21/2021] [Indexed: 11/12/2022] Open
Abstract
Segmentation of axons in light and electron micrographs allows for quantitative high-resolution analysis of nervous tissues, but varied axonal dispersion angles result in over-estimates of fiber sizes. To overcome this technical challenge, we developed a novel shape-adjusted ellipse (SAE) determination of axonal size and myelination as an all-inclusive and non-biased tool to correct for oblique nerve fiber presentations. Our new resource was validated by light and electron microscopy against traditional methods of determining nerve fiber size and myelination in rhesus macaques as a model system. We performed detailed segmental mapping and characterized the morphological signatures of autonomic and motor fibers in primate lumbosacral ventral roots (VRs). An en bloc inter-subject variability for the preganglionic parasympathetic fibers within the L7-S2 VRs was determined. The SAE approach allows for morphological ground truth data collection and assignment of individual axons to functional phenotypes with direct implications for fiber mapping and neuromodulation studies.
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Affiliation(s)
- Petra M Bartmeyer
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,School of Electrical and Computer Engineering at University of Campinas, Campinas, SP, Brazil
| | - Natalia P Biscola
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Leif A Havton
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA. .,Departments of Neurology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. .,Departments of Neurology and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA. .,Neurology Service and RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Administration Medical Center, Bronx, NY, USA.
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19
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Gordon T. Peripheral Nerve Regeneration and Muscle Reinnervation. Int J Mol Sci 2020; 21:ijms21228652. [PMID: 33212795 PMCID: PMC7697710 DOI: 10.3390/ijms21228652] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/24/2022] Open
Abstract
Injured peripheral nerves but not central nerves have the capacity to regenerate and reinnervate their target organs. After the two most severe peripheral nerve injuries of six types, crush and transection injuries, nerve fibers distal to the injury site undergo Wallerian degeneration. The denervated Schwann cells (SCs) proliferate, elongate and line the endoneurial tubes to guide and support regenerating axons. The axons emerge from the stump of the viable nerve attached to the neuronal soma. The SCs downregulate myelin-associated genes and concurrently, upregulate growth-associated genes that include neurotrophic factors as do the injured neurons. However, the gene expression is transient and progressively fails to support axon regeneration within the SC-containing endoneurial tubes. Moreover, despite some preference of regenerating motor and sensory axons to “find” their appropriate pathways, the axons fail to enter their original endoneurial tubes and to reinnervate original target organs, obstacles to functional recovery that confront nerve surgeons. Several surgical manipulations in clinical use, including nerve and tendon transfers, the potential for brief low-frequency electrical stimulation proximal to nerve repair, and local FK506 application to accelerate axon outgrowth, are encouraging as is the continuing research to elucidate the molecular basis of nerve regeneration.
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Affiliation(s)
- Tessa Gordon
- Department of Surgery, University of Toronto, Division of Plastic Reconstructive Surgery, 06.9706 Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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20
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Roberts TPL, Bloy L, Ku M, Blaskey L, Jackel CR, Edgar JC, Berman JI. A Multimodal Study of the Contributions of Conduction Velocity to the Auditory Evoked Neuromagnetic Response: Anomalies in Autism Spectrum Disorder. Autism Res 2020; 13:1730-1745. [PMID: 32924333 DOI: 10.1002/aur.2369] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 06/22/2020] [Accepted: 06/26/2020] [Indexed: 11/12/2022]
Abstract
This multimodal imaging study used magnetoencephalography, diffusion magnetic resonance imaging (MRI), and gamma-aminobutyric acid (GABA) magnetic resonance spectroscopy (MRS) to identify and contrast the multiple physiological mechanisms associated with auditory processing efficiency in typically developing (TD) children and children with autism spectrum disorder (ASD). Efficient transmission of auditory input between the ear and auditory cortex is necessary for rapid encoding of auditory sensory information. It was hypothesized that the M50 auditory evoked response latency would be modulated by white matter microstructure (indexed by diffusion MRI) and by tonic inhibition (indexed by GABA MRS). Participants were 77 children diagnosed with ASD and 40 TD controls aged 7-17 years. A model of M50 latency with auditory radiation fractional anisotropy and age as independent variables was able to predict 52% of M50 latency variance in TD children, but only 12% of variance in ASD. The ASD group exhibited altered patterns of M50 latency modulation characterized by both higher variance and deviation from the expected structure-function relationship established with the TD group. The TD M50 latency model was used to identify a subpopulation of ASD who are significant "outliers" to the TD model. The ASD outlier group exhibited unexpectedly long M50 latencies in conjunction with significantly lower GABA levels. These findings indicate the dependence of electrophysiologic sensory response latency on underlying microstructure (white matter) and neurochemistry (synaptic activity). This study demonstrates the use of biologically based measures to stratify ASD according to their brain-level "building blocks" as an alternative to their behavioral phenotype. LAY SUMMARY: Children with ASD often have a slower brain response when hearing sounds. This study used multiple brain imaging techniques to examine the structural and neurochemical factors which control the brain's response time to auditory tones in children with ASD and TD children. The relationship between brain imaging measures and brain response time was also used to identify ASD subgroups. Autism Res 2020, 13: 1730-1745. © 2020 International Society for Autism Research and Wiley Periodicals LLC.
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Affiliation(s)
- Timothy P L Roberts
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Luke Bloy
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Matt Ku
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Lisa Blaskey
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Child and Adolescent Psychiatry and Behavioral Sciences, Center for Autism Research, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Carissa R Jackel
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Division of Developmental and Behavioral Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - James Christopher Edgar
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jeffrey I Berman
- Department of Radiology, Lurie Family Foundations MEG Imaging Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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21
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Ji W, Hou B, Tang H, Cai M, Zheng W. Investigation of the effects of laminin present in the basal lamina of the peripheral nervous system on axon regeneration and remyelination using the nerve acellular scaffold. J Biomed Mater Res A 2020; 108:1673-1687. [PMID: 32196907 DOI: 10.1002/jbm.a.36933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 03/03/2020] [Accepted: 03/09/2020] [Indexed: 12/14/2022]
Abstract
This study aimed to investigate the effects of laminin (LN) located in the basal lamina, which are important components of the peripheral nervous system-extracellular matrix, on axon regeneration and remyelination. Nerve acellular scaffolds (NASs) (S-untreated) were prepared using the acellular technique. The active component LN in the NASs was blocked (S-LN- ) or upregulated (S-LN+ ); S-LN+ contained seven times more LN than did the S-untreated group. The adhesion capacity of Schwann cells (SCs) to the three types of NAS (S-untreated, S-LN- , and S-LN+ ) was assessed in vitro. Our results showed that the adhesion of SCs to the NASs was significantly reduced in the S-LN- group, whereas no difference was observed between the S-LN+ and S-untreated groups. The pretreated NASs were used to repair nerves in a nerve injury mouse model with the animals divided into four groups (S-LN- group, S-untreated group, S-LN+ group, and autograft group). Two weeks after surgery, although there was no difference in the S-LN- group, S-untreated group and S-LN+ group, the newly formed basal lamina in the S-LN- group were significantly lower than those in the other two groups. Four weeks after surgery, the S-LN+ group had higher numbers of newly generated axons and their calibers, more myelinated fibers, thicker myelin sheaths, increased myelin basic protein expression, and improved recovery of neural function compared to those of the S-LN- and S-untreated groups, but all of these parameters were significantly worse than those of the autograft group. Downregulation of the LN level in the NAS leads to a reduction in all of the above parameters.
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Affiliation(s)
- Wanqing Ji
- Department of Obstetrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Bo Hou
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Hengxin Tang
- Department of Neurosurgery, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Meiqin Cai
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Wenhan Zheng
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
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22
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Roles of Progesterone, Testosterone and Their Nuclear Receptors in Central Nervous System Myelination and Remyelination. Int J Mol Sci 2020; 21:ijms21093163. [PMID: 32365806 PMCID: PMC7246940 DOI: 10.3390/ijms21093163] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/14/2022] Open
Abstract
Progesterone and testosterone, beyond their roles as sex hormones, are neuroactive steroids, playing crucial regulatory functions within the nervous system. Among these, neuroprotection and myelin regeneration are important ones. The present review aims to discuss the stimulatory effects of progesterone and testosterone on the process of myelination and remyelination. These effects have been demonstrated in vitro (i.e., organotypic cultures) and in vivo (cuprizone- or lysolecithin-induced demyelination and experimental autoimmune encephalomyelitis (EAE)). Both steroids stimulate myelin formation and regeneration by acting through their respective intracellular receptors: progesterone receptors (PR) and androgen receptors (AR). Activation of these receptors results in multiple events involving direct transcription and translation, regulating general homeostasis, cell proliferation, differentiation, growth and myelination. It also ameliorates immune response as seen in the EAE model, resulting in a significant decrease in inflammation leading to a fast recovery. Although natural progesterone and testosterone have a therapeutic potential, their synthetic derivatives—the 19-norprogesterone (nestorone) and 7α-methyl-nortestosterone (MENT), already used as hormonal contraception or in postmenopausal hormone replacement therapies, may offer enhanced benefits for myelin repair. We summarize here a recent advancement in the field of myelin biology, to treat demyelinating disorders using the natural as well as synthetic analogs of progesterone and testosterone.
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23
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Liu J, Kim YS, Richardson CE, Tom A, Ramakrishnan C, Birey F, Katsumata T, Chen S, Wang C, Wang X, Joubert LM, Jiang Y, Wang H, Fenno LE, Tok JBH, Pașca SP, Shen K, Bao Z, Deisseroth K. Genetically targeted chemical assembly of functional materials in living cells, tissues, and animals. Science 2020; 367:1372-1376. [PMID: 32193327 DOI: 10.1126/science.aay4866] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 01/21/2020] [Indexed: 12/30/2022]
Abstract
The structural and functional complexity of multicellular biological systems, such as the brain, are beyond the reach of human design or assembly capabilities. Cells in living organisms may be recruited to construct synthetic materials or structures if treated as anatomically defined compartments for specific chemistry, harnessing biology for the assembly of complex functional structures. By integrating engineered-enzyme targeting and polymer chemistry, we genetically instructed specific living neurons to guide chemical synthesis of electrically functional (conductive or insulating) polymers at the plasma membrane. Electrophysiological and behavioral analyses confirmed that rationally designed, genetically targeted assembly of functional polymers not only preserved neuronal viability but also achieved remodeling of membrane properties and modulated cell type-specific behaviors in freely moving animals. This approach may enable the creation of diverse, complex, and functional structures and materials within living systems.
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Affiliation(s)
- Jia Liu
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yoon Seok Kim
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | | | - Ariane Tom
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Charu Ramakrishnan
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Fikri Birey
- Department of Psychiatry, Stanford University, Stanford, CA 94305, USA
| | - Toru Katsumata
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Shucheng Chen
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Cheng Wang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
| | - Xiao Wang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Lydia-Marie Joubert
- Cell Sciences Imaging Facility, Stanford University, Stanford, CA 94305, USA
| | - Yuanwen Jiang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Huiliang Wang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Lief E Fenno
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.,Department of Psychiatry, Stanford University, Stanford, CA 94305, USA
| | - Jeffrey B-H Tok
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Sergiu P Pașca
- Department of Psychiatry, Stanford University, Stanford, CA 94305, USA
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. .,Department of Psychiatry, Stanford University, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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24
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Manzanera Esteve IV, Farinas AF, Pollins AC, Nussenbaum ME, Cardwell NL, Kang H, Does MD, Thayer WP, Dortch RD. Probabilistic Assessment of Nerve Regeneration with Diffusion MRI in Rat Models of Peripheral Nerve Trauma. Sci Rep 2019; 9:19686. [PMID: 31873165 PMCID: PMC6928159 DOI: 10.1038/s41598-019-56215-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 12/05/2019] [Indexed: 11/22/2022] Open
Abstract
Nerve regeneration after injury must occur in a timely fashion to restore function. Unfortunately, current methods (e.g., electrophysiology) provide limited information following trauma, resulting in delayed management and suboptimal outcomes. Herein, we evaluated the ability of diffusion MRI to monitor nerve regeneration after injury/repair. Sprague-Dawley rats were divided into three treatment groups (sham = 21, crush = 23, cut/repair = 19) and ex vivo diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) was performed 1-12 weeks post-surgery. Behavioral data showed a distinction between crush and cut/repair nerves at 4 weeks. This was consistent with DTI, which found that thresholds based on the ratio of radial and axial diffusivities (RD/AD = 0.40 ± 0.02) and fractional anisotropy (FA = 0.53 ± 0.01) differentiated crush from cut/repair injuries. By the 12th week, cut/repair nerves whose behavioral data indicated a partial recovery were below the RD/AD threshold (and above the FA threshold), while nerves that did not recover were on the opposite side of each threshold. Additional morphometric analysis indicated that DTI-derived normalized scalar indices report on axon density (RD/AD: r = -0.54, p < 1e-3; FA: r = 0.56, p < 1e-3). Interestingly, higher-order DKI analyses did not improve our ability classify recovery. These findings suggest that DTI may provide promising biomarkers for distinguishing successful/unsuccessful nerve repairs and potentially identify cases that require reoperation.
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Affiliation(s)
- Isaac V Manzanera Esteve
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, USA
- Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, USA
| | - Angel F Farinas
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, USA
| | - Alonda C Pollins
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, USA
| | - Marlieke E Nussenbaum
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, USA
| | - Nancy L Cardwell
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, USA
| | - Hakmook Kang
- Vanderbilt University Medical Center, Department of Biostatistics, Nashville, TN, USA
| | - Mark D Does
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, USA
- Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, USA
- Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, USA
| | - Wesley P Thayer
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, USA
- Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, USA
| | - Richard D Dortch
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, USA.
- Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, USA.
- Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, USA.
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25
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Forgrave LM, Ma M, Best JR, DeMarco ML. The diagnostic performance of neurofilament light chain in CSF and blood for Alzheimer's disease, frontotemporal dementia, and amyotrophic lateral sclerosis: A systematic review and meta-analysis. ALZHEIMER'S & DEMENTIA: DIAGNOSIS, ASSESSMENT & DISEASE MONITORING 2019; 11:730-743. [PMID: 31909174 PMCID: PMC6939029 DOI: 10.1016/j.dadm.2019.08.009] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Introduction A systematic review and meta-analysis was performed regarding the diagnostic performance of neurofilament light chain (NfL) in CSF and blood. Methods A database search was conducted for NfL biomarker studies in the context of Alzheimer's disease (AD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS) compared with controls (i.e., cognitively unimpaired, mild cognitive impairment, or disease mimics). Results In groups with a sufficient number of studies, the performance of NfL in blood and CSF was similar. Compared with disease mimics, we observed that CSF NfL had strong discriminatory power for ALS, modest discriminatory power for FTD, and no discriminatory power for AD. NfL provided the greatest separation between ALS and cognitively unimpaired controls in both the blood and CSF, followed by FTD (CSF and blood), then AD (blood and CSF). Discussion Comparable performance of CSF and blood NfL in many groups demonstrates the promise of NfL as a noninvasive biomarker of neurodegeneration; however, its utility in clinically meaningful scenarios requires greater scrutiny. Toward clinical implementation, a more comprehensive understanding of NfL concentrations in disease subtypes with overlapping phenotypes and at defined stages of disease, and the development of a harmonization program, are warranted.
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Affiliation(s)
- Lauren M Forgrave
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - Matthew Ma
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - John R Best
- Department of Psychiatry, University of British Columbia, Vancouver, Canada
| | - Mari L DeMarco
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.,Department of Pathology and Laboratory Medicine, St. Paul's Hospital, Providence Health Care, Vancouver, Canada
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26
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Chittoor-Vinod VG, Bazick H, Todd AG, Falk D, Morelli KH, Burgess RW, Foster TC, Notterpek L. HSP90 Inhibitor, NVP-AUY922, Improves Myelination in Vitro and Supports the Maintenance of Myelinated Axons in Neuropathic Mice. ACS Chem Neurosci 2019; 10:2890-2902. [PMID: 31017387 PMCID: PMC6588339 DOI: 10.1021/acschemneuro.9b00105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
![]()
Hereditary
demyelinating neuropathies linked to peripheral myelin
protein 22 (PMP22) involve the disruption of normal protein trafficking
and are therefore relevant targets for chaperone therapy. Using a
small molecule HSP90 inhibitor, EC137, in cell culture models, we
previously validated the chaperone pathway as a viable target for
therapy development. Here, we tested five commercially available inhibitors
of HSP90 and identified BIIB021 and AUY922 to support Schwann cell
viability and enhance chaperone expression. AUY922 showed higher efficacy,
compared to BIIB021, in enhancing myelin synthesis in dorsal root
ganglion explant cultures from neuropathic mice. For in vivo testing,
we randomly assigned 2–3 month old C22 and 6 week old Trembler
J (TrJ) mice to receive two weekly injections of either vehicle or
AUY922 (2 mg/kg). By the intraperitoneal (i.p.) route, the drug was
well-tolerated by all mice over the 5 month long study, without influence
on body weight or general grooming behavior. AUY922 improved the maintenance
of myelinated nerves of both neuropathic models and attenuated the
decline in rotarod performance and peak muscle force production in
C22 mice. These studies highlight the significance of proteostasis
in neuromuscular function and further validate the HSP90 pathway as
a therapeutic target for hereditary neuropathies.
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Affiliation(s)
- Vinita G. Chittoor-Vinod
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, 1149 Newell Drive, Box 100244, Gainesville, Florida 32610-0244, United States
| | - Hannah Bazick
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, 1149 Newell Drive, Box 100244, Gainesville, Florida 32610-0244, United States
| | - Adrian G. Todd
- Department of Pediatrics, Powell Gene Therapy Center, University of Florida, Gainesville, Florida 32611, United States
| | - Darin Falk
- Department of Pediatrics, Powell Gene Therapy Center, University of Florida, Gainesville, Florida 32611, United States
| | - Kathryn H. Morelli
- The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469, United States
- The Jackson Laboratory, Bar Harbor, Maine 04609, United States
| | - Robert W. Burgess
- The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469, United States
- The Jackson Laboratory, Bar Harbor, Maine 04609, United States
| | - Thomas C. Foster
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, 1149 Newell Drive, Box 100244, Gainesville, Florida 32610-0244, United States
| | - Lucia Notterpek
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, 1149 Newell Drive, Box 100244, Gainesville, Florida 32610-0244, United States
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27
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Kuatsjah E, Khoshnam M, Menon C. Investigation on the effect of noisy galvanic vestibular stimulation on fine motor skills during a visuomotor task in healthy participants. PLoS One 2019; 14:e0216214. [PMID: 31048906 PMCID: PMC6497271 DOI: 10.1371/journal.pone.0216214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 04/16/2019] [Indexed: 11/24/2022] Open
Abstract
Noisy galvanic vestibular stimulation (nGVS) has been shown to improve dynamic walking stability, affect postural responses, enhance balance in healthy subjects, and influence motor performance in individuals with Parkinson’s disease. Although the studies to fully characterize the effect of nGVS are still ongoing, stochastic resonance theory which states that the addition of noisy signal may enhance a weak sensory input signals transmission in a non-linear system may provide a possible explanation for the observed positive effects of nGVS. This study explores the effect of nGVS on fine tracking behavior in healthy subjects. Ten healthy participants performed a computer-based visuomotor task by controlling an object with a joystick to follow an amplitude-modulated signal path while simultaneously receiving a sham or pink noise nGVS. The stimulation was generated to have a zero-mean, linearly detrended 1/f-type power spectrum, Gaussian distribution within 0.1–10 Hz range, and a standard deviation (SD) set to 90% based on each participant’s cutaneous threshold value. Results show that simultaneous nGVS delivery statistically improved the tracking performance with a decreased root-mean-squared error of 5.71±6.20% (mean±SD), a decreased time delay of 11.88±9.66% (mean±SD), and an increased signal-to-noise ratio of 2.93% (median, interquartile range (IQR) 3.31%). This study showed evidence that nGVS may be beneficial in improving sensorimotor performance during a fine motor tracking task requiring fine wrist movement in healthy subjects. Further research with a more comprehensive subset of tasks is required to fully characterize the effects of nGVS on fine motor skills.
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Affiliation(s)
- Eunice Kuatsjah
- Menrva Research Group, Schools of Mechatronic Systems Engineering and Engineering Science, Simon Fraser University, Metro Vancouver, British Columbia, Canada
| | - Mahta Khoshnam
- Menrva Research Group, Schools of Mechatronic Systems Engineering and Engineering Science, Simon Fraser University, Metro Vancouver, British Columbia, Canada
| | - Carlo Menon
- Menrva Research Group, Schools of Mechatronic Systems Engineering and Engineering Science, Simon Fraser University, Metro Vancouver, British Columbia, Canada
- * E-mail:
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28
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Berman S, Filo S, Mezer AA. Modeling conduction delays in the corpus callosum using MRI-measured g-ratio. Neuroimage 2019; 195:128-139. [PMID: 30910729 DOI: 10.1016/j.neuroimage.2019.03.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 11/26/2022] Open
Abstract
Conduction of action potentials along myelinated axons is affected by their structural features, such as the axonal g-ratio, the ratio between the inner and outer diameters of the myelin sheath surrounding the axon. The effect of g-ratio variance on conduction properties has been quantitatively evaluated using single-axon models. It has recently become possible to estimate a g-ratio weighted measurement in vivo using quantitative MRI. Nevertheless, it is still unclear whether the variance in the g-ratio in the healthy human brain leads to significant differences in conduction velocity. In this work we tested whether the g-ratio MRI measurement can be used to predict conduction delays in the corpus callosum. We present a comprehensive framework in which the structural properties of fibers (i.e. length and g-ratio, measured using MRI), are incorporated in a biophysical model of axon conduction, to model conduction delays of long-range white matter fibers. We applied this framework to the corpus callosum, and found conduction delay estimates that are compatible with previously estimated values of conduction delays. We account for the variance in the velocity given the axon diameter distribution in the splenium, mid-body and genu, to further compare the fibers within the corpus callosum. Conduction delays have been suggested to increase with age. Therefore, we investigated whether there are differences in the g-ratio and the fiber length between young and old adults, and whether this leads to a difference in conduction speed and delays. We found very small differences between the predicted delays of the two groups in the motor fibers of the corpus callosum. We also found that the motor fibers of the corpus callosum have the fastest conduction estimates. Using the axon diameter distributions, we found that the occipital fibers have the slowest estimations, while the frontal and motor fiber tracts have similar estimates. Our study provides a framework for predicting conduction latencies in vivo. The framework could have major implications for future studies of white matter diseases and large range network computations. Our results highlight the need for improving additional in vivo measurements of white matter microstructure.
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Affiliation(s)
- S Berman
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
| | - S Filo
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - A A Mezer
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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29
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Abe Y, Komaki Y, Seki F, Shibata S, Okano H, Tanaka KF. Correlative study using structural MRI and super-resolution microscopy to detect structural alterations induced by long-term optogenetic stimulation of striatal medium spiny neurons. Neurochem Int 2019; 125:163-174. [PMID: 30825601 DOI: 10.1016/j.neuint.2019.02.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 11/27/2022]
Abstract
Striatal medium spiny neurons (MSNs) control motor function. Hyper- or hypo-activity of MSNs coincides with basal ganglia-related movement disorders. Based on the assumption that lasting alterations in neuronal activity lead to structural changes in the brain, understanding these structural alterations may be used to infer MSN functional abnormalities. To infer MSN function from structural data, understanding how long-lasting alterations in MSN activity affect brain morphology is essential. To address this, we utilized a simplified model of functional induction by stimulating MSNs expressing channelrhodopsin 2 (ChR2). Subsequent structural alterations which induced long-term activity changes in these MSNs were investigated in the striatal pathway and its associated regions by diffusion tensor imaging (DTI) and histological assessment with super-resolution microscopy. DTI detected changes in the striatum, substantia nigra, and motor cortex. Histological assessment found a reduction in the diameter of myelinated cortical axons as well as MSN dendrites and axons. The structural changes showed a high correlation between DTI parameters and histological data. These results demonstrated that long-term neural activation in the MSNs alters the diameter of MSN and cortical neurons fibers. This study provides a tool for understanding the causal relationship between functional and structural alterations.
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Affiliation(s)
- Yoshifumi Abe
- Department of Neuropsychiatry, Keio University School of Medicine, Japan.
| | - Yuji Komaki
- Department of Physiology, Keio University School of Medicine, Japan; Live Imaging Center, Central Institute for Experimental Animals, Japan
| | - Fumiko Seki
- Department of Physiology, Keio University School of Medicine, Japan; Live Imaging Center, Central Institute for Experimental Animals, Japan
| | - Shinsuke Shibata
- Department of Physiology, Keio University School of Medicine, Japan; Electron Microscope Laboratory, Keio University School of Medicine, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Japan; Electron Microscope Laboratory, Keio University School of Medicine, Japan; Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, Keio University School of Medicine, Japan
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30
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McCorquodale D, Smith AG. Clinical electrophysiology of axonal polyneuropathies. HANDBOOK OF CLINICAL NEUROLOGY 2019; 161:217-240. [PMID: 31307603 DOI: 10.1016/b978-0-444-64142-7.00051-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Axonal neuropathies encompass a wide range of acquired and inherited disorders with electrophysiologic characteristics that arise from the unique neurophysiology of the axon. Accurate interpretation of nerve conduction studies and electromyography requires an in-depth understanding of the pathophysiology of the axon. Here we review the unique neurophysiologic properties of the axon and how they relate to clinical electrodiagnostic features. We review the length-dependent Wallerian or "dying-back" processes as well as the emerging body of literature from acquired axonal neuropathies that highlights the importance of axonal disease at the nodes of Ranvier. Neurophysiologic features of individual inherited and acquired axonal diseases, including primary nerve disease as well as systemic immune mediated, metabolic, and toxic diseases involving the peripheral nerve, are reviewed. This comprehensive review of electrodiagnostic findings coupled with the current understanding of pathophysiology will aid the clinician in the evaluation of axonal polyneuropathies.
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Affiliation(s)
- Donald McCorquodale
- Department of Neurology, Virginia Commonwealth University, Richmond, VA, United States
| | - A Gordon Smith
- Department of Neurology, Virginia Commonwealth University, Richmond, VA, United States.
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31
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Kurz FT, Buschle LR, Hahn A, Jende JME, Bendszus M, Heiland S, Ziener CH. Diffusion effects in myelin sheath free induction decay. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 297:61-75. [PMID: 30366221 DOI: 10.1016/j.jmr.2018.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
Myelin sheath microstructure and composition produce MR signal decay characteristics that can be used to evaluate status and outcome of demyelinating disease. We extend a recently proposed model of neuronal magnetic susceptibility, that accounts for both the structural and inherent anisotropy of the myelin sheath, by including the whole dynamic range of diffusion effects. The respective Bloch-Torrey equation for local spin dephasing is solved with a uniformly convergent perturbation expansion method, and the resulting magnetization decay is validated with a numerical solution based on a finite difference method. We show that a variation of diffusion strengths can lead to substantially different MR signal decay curves. Our results may be used to adjust or control simulations for water diffusion in neuronal structures.
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Affiliation(s)
- F T Kurz
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
| | - L R Buschle
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany; Heidelberg University, Faculty of Physics and Astronomy, INF 227, D-69120 Heidelberg, Germany
| | - A Hahn
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - J M E Jende
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - M Bendszus
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - S Heiland
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany
| | - C H Ziener
- Heidelberg University Hospital, INF 400, D-69120 Heidelberg, Germany; German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
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32
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Klok MD, Bugiani M, de Vries SI, Gerritsen W, Breur M, van der Sluis S, Heine VM, Kole MHP, Baron W, van der Knaap MS. Axonal abnormalities in vanishing white matter. Ann Clin Transl Neurol 2018; 5:429-444. [PMID: 29687020 PMCID: PMC5899913 DOI: 10.1002/acn3.540] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 12/30/2017] [Indexed: 12/03/2022] Open
Abstract
Objective We aimed to study the occurrence and development of axonal pathology and the influence of astrocytes in vanishing white matter. Methods Axons and myelin were analyzed using electron microscopy and immunohistochemistry on Eif2b4 and Eif2b5 single‐ and double‐mutant mice and patient brain tissue. In addition, astrocyte‐forebrain co‐culture studies were performed. Results In the corpus callosum of Eif2b5‐mutant mice, myelin sheath thickness, axonal diameter, and G‐ratio developed normally up to 4 months. At 7 months, however, axons had become thinner, while in control mice axonal diameters had increased further. Myelin sheath thickness remained close to normal, resulting in an abnormally low G‐ratio in Eif2b5‐mutant mice. In more severely affected Eif2b4‐Eif2b5 double‐mutants, similar abnormalities were already present at 4 months, while in milder affected Eif2b4 mutants, few abnormalities were observed at 7 months. Additionally, from 2 months onward an increased percentage of thin, unmyelinated axons and increased axonal density were present in Eif2b5‐mutant mice. Co‐cultures showed that Eif2b5 mutant astrocytes induced increased axonal density, also in control forebrain tissue, and that control astrocytes induced normal axonal density, also in mutant forebrain tissue. In vanishing white matter patient brains, axons and myelin sheaths were thinner than normal in moderately and severely affected white matter. In mutant mice and patients, signs of axonal transport defects and cytoskeletal abnormalities were minimal. Interpretation In vanishing white matter, axons are initially normal and atrophy later. Astrocytes are central in this process. If therapy becomes available, axonal pathology may be prevented with early intervention.
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Affiliation(s)
- Melanie D Klok
- Department of Pediatrics/Child Neurology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Marianna Bugiani
- Department of Pathology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Sharon I de Vries
- Department of Axonal Signaling Netherlands Institute for Neuroscience Amsterdam The Netherlands
| | - Wouter Gerritsen
- Department of Pathology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Marjolein Breur
- Department of Pathology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Sophie van der Sluis
- Department of Complex Trait Genetics Center for Neurogenomics and Cognitive Research Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Vivi M Heine
- Department of Pediatrics/Child Neurology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands.,Department of Complex Trait Genetics Center for Neurogenomics and Cognitive Research Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands
| | - Maarten H P Kole
- Department of Axonal Signaling Netherlands Institute for Neuroscience Amsterdam The Netherlands.,Cell Biology Faculty of Science Utrecht University Utrecht The Netherlands
| | - Wia Baron
- Department of Cell Biology University Medical Center Groningen University of Groningen Groningen The Netherlands
| | - Marjo S van der Knaap
- Department of Pediatrics/Child Neurology Amsterdam Neuroscience VU University Medical Centre Amsterdam The Netherlands.,Department of Functional Genomics Center for Neurogenomics and Cognitive Research Amsterdam Neuroscience VU University Amsterdam The Netherlands
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33
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Saller MM, Huettl RE, Mayer JM, Feuchtinger A, Krug C, Holzbach T, Volkmer E. Validation of a novel animal model for sciatic nerve repair with an adipose-derived stem cell loaded fibrin conduit. Neural Regen Res 2018; 13:854-861. [PMID: 29863016 PMCID: PMC5998632 DOI: 10.4103/1673-5374.232481] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Despite the regenerative capabilities of peripheral nerves, severe injuries or neuronal trauma of critical size impose immense hurdles for proper restoration of neuro-muscular circuitry. Autologous nerve grafts improve re-establishment of connectivity, but also comprise substantial donor site morbidity. We developed a rat model which allows the testing of different cell applications, i.e., mesenchymal stem cells, to improve nerve regeneration in vivo. To mimic inaccurate alignment of autologous nerve grafts with the injured nerve, a 20 mm portion of the sciatic nerve was excised, and sutured back in place in reversed direction. To validate the feasibility of our novel model, a fibrin gel conduit containing autologous undifferentiated adipose-derived stem cells was applied around the coaptation sites and compared to autologous nerve grafts. After evaluating sciatic nerve function for 16 weeks postoperatively, animals were sacrificed, and gastrocnemius muscle weight was determined along with morphological parameters (g-ratio, axon density & diameter) of regenerating axons. Interestingly, the addition of undifferentiated adipose-derived stem cells resulted in a significantly improved re-myelination, axon ingrowth and functional outcome, when compared to animals without a cell seeded conduit. The presented model thus displays several intriguing features: it imitates a certain mismatch in size, distribution and orientation of axons within the nerve coaptation site. The fibrin conduit itself allows for an easy application of cells and, as a true critical-size defect model, any observed improvement relates directly to the performed intervention. Since fibrin and adipose-derived stem cells have been approved for human applications, the technique can theoretically be performed on humans. Thus, we suggest that the model is a powerful tool to investigate cell mediated assistance of peripheral nerve regeneration.
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Affiliation(s)
- Maximilian M Saller
- Experimental Surgery and Regenerative Medicine (ExperiMed), Department of General, Trauma and Reconstructive Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Rosa-Eva Huettl
- Max-Planck-Institute of Psychiatry, Department of Stress Neurobiology and Neurogenetics, Munich, Germany
| | - Julius M Mayer
- Experimental Surgery and Regenerative Medicine (ExperiMed), Department of General, Trauma and Reconstructive Surgery, Ludwig-Maximilians-University (LMU); Department of Hand-, Plastic- and Aesthetic Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Annette Feuchtinger
- Research Unit Analytical Pathology, Munich, Helmholtz Zentrum Muenchen-German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Christian Krug
- Department of Hand-, Plastic- and Aesthetic Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany; Department of Hand and Plastic Surgery, Spital Thurgau AG, Frauenfeld, Switzerland
| | - Thomas Holzbach
- Department of Hand-, Plastic- and Aesthetic Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany; Department of Hand and Plastic Surgery, Spital Thurgau AG, Frauenfeld, Switzerland
| | - Elias Volkmer
- Experimental Surgery and Regenerative Medicine (ExperiMed), Department of General, Trauma and Reconstructive Surgery, Ludwig-Maximilians-University (LMU); Department of Hand-, Plastic- and Aesthetic Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany
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Grier MD, West KL, Kelm ND, Fu C, Does MD, Parker B, McBrier E, Lagrange AH, Ess KC, Carson RP. Loss of mTORC2 signaling in oligodendrocyte precursor cells delays myelination. PLoS One 2017; 12:e0188417. [PMID: 29161318 PMCID: PMC5697806 DOI: 10.1371/journal.pone.0188417] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 11/07/2017] [Indexed: 11/26/2022] Open
Abstract
Myelin abnormalities are increasingly being recognized as an important component of a number of neurologic developmental disorders. The integration of many signaling pathways and cell types are critical for correct myelinogenesis. The PI3-K and mechanistic target of rapamycin (mTOR) pathways have been found to play key roles. mTOR is found within two distinct complexes, mTORC1 and mTORC2. mTORC1 activity has been shown to play a major role during myelination, while the role of mTORC2 is not yet well understood. To determine the role of mTORC2 signaling in myelinogenesis, we generated a mouse lacking the critical mTORC2 component Rictor in oligodendrocyte precursors (OPCs). Targeted deletion of Rictor in these cells decreases and delays the expression of myelin related proteins and reduces the size of cerebral white matter tracts. This is developmentally manifest as a transient reduction in myelinated axon density and g-ratio. OPC cell number is reduced at birth without detectable change in proliferation with proportional reductions in mature oligodendrocyte number at P15. The total number of oligodendrocytes as well as extent of myelination, does improve over time. Adult conditional knock-out (CKO) animals do not demonstrate a behavioral phenotype likely due in part to preserved axonal conduction velocities. These data support and extend prior studies demonstrating an important but transient contribution of mTORC2 signaling to myelin development.
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Affiliation(s)
- Mark D. Grier
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Kathryn L. West
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Nathaniel D. Kelm
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Cary Fu
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mark D. Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Brittany Parker
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eleanor McBrier
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Andre H. Lagrange
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Kevin C. Ess
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Robert P. Carson
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Coupled circumferential and axial tension driven by actin and myosin influences in vivo axon diameter. Sci Rep 2017; 7:14188. [PMID: 29079766 PMCID: PMC5660205 DOI: 10.1038/s41598-017-13830-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/29/2017] [Indexed: 01/07/2023] Open
Abstract
It has long been known that neuronal axons are contractile. They actively maintain rest tension along the longitudinal direction both in vitro and in vivo. Here we show evidence that embryonic drosophila axons also actively maintain contractility/tension along the circumferential direction. We used confocal microscopy and spatial light interference microscopy to monitor axonal diameter along their length. We observed a decrease in diameter when microtubules are disrupted and an increase in diameter when actin filaments or myosin II are disrupted. Interestingly, active diameter reduction occurred consistently when axons were subjected to manipulations known to increase axial tension, suggesting that tension can be coupled in the axial and circumferential direction. This is further supported by the remarkably similar time constants for diameter reduction and rest tension increase of slackened axons. We infer that the actomyosin-driven circumferential contraction/hoop tension applies a squeezing force on the microtubule bundle of the axons. This hoop tension is balanced by the restoring force of the microtubule bundle. Therefore, axonal diameter increased when actin/myosin disrupting drugs relaxed the hoop tension and decreased when microtubule disrupting drug relaxed the restoring force. Circumferential tension thus can regulate axonal diameter and volume, as well as potentially microtubules alignment, inter-tubular spacing, and, by extension, axonal transport.
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36
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Lee JY, Kim MJ, Li L, Velumian AA, Aui PM, Fehlings MG, Petratos S. Nogo receptor 1 regulates Caspr distribution at axo-glial units in the central nervous system. Sci Rep 2017; 7:8958. [PMID: 28827698 PMCID: PMC5567129 DOI: 10.1038/s41598-017-09405-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/24/2017] [Indexed: 11/09/2022] Open
Abstract
Axo-glial units are highly organised microstructures propagating saltatory conduction and are disrupted during multiple sclerosis (MS). Nogo receptor 1 (NgR1) has been suggested to govern axonal damage during the progression of disease in the MS-like mouse model, experimental autoimmune encephalomyelitis (EAE). Here we have identified that adult ngr1 -/- mice, previously used in EAE and spinal cord injury experiments, display elongated paranodes, and nodes of Ranvier. Unstructured paranodal regions in ngr1 -/- mice are matched with more distributed expression pattern of Caspr. Compound action potentials of optic nerves and spinal cords from naïve ngr1 -/- mice are delayed and reduced. Molecular interaction studies revealed enhanced Caspr cleavage. Our data suggest that NgR1 may regulate axo-myelin ultrastructure through Caspr-mediated adhesion, regulating the electrophysiological signature of myelinated axons of central nervous system (CNS).
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Affiliation(s)
- Jae Young Lee
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia
- ToolGen, Inc., #1204, Byucksan Digital Valley 6-cha, Seoul, South Korea
| | - Min Joung Kim
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia
| | - Lijun Li
- Krembil Research Institute, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Alexander A Velumian
- Krembil Research Institute, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Krembil Neuroscience Centre, University Health Network, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Pei Mun Aui
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia
| | - Michael G Fehlings
- Krembil Research Institute, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Krembil Neuroscience Centre, University Health Network, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Steven Petratos
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia.
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Bahey NG, Gadalla KKE, McGonigal R, Bailey MES, Edgar JM, Cobb SR. Reduced axonal diameter of peripheral nerve fibers in a mouse model of Rett syndrome. Neuroscience 2017; 358:261-268. [PMID: 28687309 DOI: 10.1016/j.neuroscience.2017.06.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/29/2022]
Abstract
Rett syndrome (RTT) is a neurological disorder characterized by motor and cognitive impairment, autonomic dysfunction and a loss of purposeful hand skills. In the majority of cases, typical RTT is caused by de novo mutations in the X-linked gene, MECP2. Alterations in the structure and function of neurons within the central nervous system of RTT patients and Mecp2-null mouse models are well established. In contrast, few studies have investigated the effects of MeCP2-deficiency on peripheral nerves. In this study, we conducted detailed morphometric as well as functional analysis of the sciatic nerves of symptomatic adult female Mecp2+/- mice. We observed a significant reduction in the mean diameter of myelinated nerve fibers in Mecp2+/- mice. In myelinated fibers, mitochondrial densities per unit area of axoplasm were significantly altered in Mecp2+/- mice. However, conduction properties of the sciatic nerve of Mecp2 knockout mice were not different from control. These subtle changes in myelinated peripheral nerve fibers in heterozygous Mecp2 knockout mice could potentially explain some RTT phenotypes.
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Affiliation(s)
- Noha G Bahey
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom; Histology Department, Faculty of Medicine, Tanta University, Egypt
| | - Kamal K E Gadalla
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom; Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Rhona McGonigal
- Institute of Infection, Immunity and Inflammation College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Mark E S Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Julia M Edgar
- Institute of Infection, Immunity and Inflammation College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Stuart R Cobb
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom.
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BACE1 across species: a comparison of the in vivo consequences of BACE1 deletion in mice and rats. Sci Rep 2017; 7:44249. [PMID: 28281673 PMCID: PMC5345047 DOI: 10.1038/srep44249] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 02/06/2017] [Indexed: 01/18/2023] Open
Abstract
Assessing BACE1 (β-site APP cleaving enzyme 1) knockout mice for general health and neurological function may be useful in predicting risks associated with prolonged pharmacological BACE1 inhibition, a treatment approach currently being developed for Alzheimer’s disease. To determine whether BACE1 deletion-associated effects in mice generalize to another species, we developed a novel Bace1−/− rat line using zinc-finger nuclease technology and compared Bace1−/− mice and rats with their Bace1+/+ counterparts. Lack of BACE1 was confirmed in Bace1−/− animals from both species. Removal of BACE1 affected startle magnitude, balance beam performance, pain response, and nerve myelination in both species. While both mice and rats lacking BACE1 have shown increased mortality, the increase was smaller and restricted to early developmental stages for rats. Bace1−/− mice and rats further differed in body weight, spontaneous locomotor activity, and prepulse inhibition of startle. While the effects of species and genetic background on these phenotypes remain difficult to distinguish, our findings suggest that BACE1’s role in myelination and some sensorimotor functions is consistent between mice and rats and may be conserved in other species. Other phenotypes differ between these models, suggesting that some effects of BACE1 inhibition vary with the biological context (e.g. species or background strain).
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Dean DC, O'Muircheartaigh J, Dirks H, Travers BG, Adluru N, Alexander AL, Deoni SCL. Mapping an index of the myelin g-ratio in infants using magnetic resonance imaging. Neuroimage 2016; 132:225-237. [PMID: 26908314 PMCID: PMC4851913 DOI: 10.1016/j.neuroimage.2016.02.040] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 02/07/2016] [Accepted: 02/12/2016] [Indexed: 12/03/2022] Open
Abstract
Optimal myelination of neuronal axons is essential for effective brain and cognitive function. The ratio of the axon diameter to the outer fiber diameter, known as the g-ratio, is a reliable measure to assess axonal myelination and is an important index reflecting the efficiency and maximal conduction velocity of white matter pathways. Although advanced neuroimaging techniques including multicomponent relaxometry (MCR) and diffusion tensor imaging afford insight into the microstructural characteristics of brain tissue, by themselves they do not allow direct analysis of the myelin g-ratio. Here, we show that by combining myelin content information (obtained with mcDESPOT MCR) with neurite density information (obtained through NODDI diffusion imaging) an index of the myelin g-ratio may be estimated. Using this framework, we present the first quantitative study of myelin g-ratio index changes across childhood, examining 18 typically developing children 3months to 7.5years of age. We report a spatio-temporal pattern of maturation that is consistent with histological and developmental MRI studies, as well as theoretical studies of the myelin g-ratio. This work represents the first ever in vivo visualization of the evolution of white matter g-ratio indices throughout early childhood.
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Affiliation(s)
- Douglas C Dean
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | | | - Holly Dirks
- Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI 02912, USA
| | - Brittany G Travers
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Kinesiology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Nagesh Adluru
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Andrew L Alexander
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Sean C L Deoni
- Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI 02912, USA; Department of Pediatric Radiology, Children's Hospital Colorado, Aurora, CO, USA; Department of Radiology, University of Colorado Denver, Denver, CO, USA
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40
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Pesaresi M, Soon-Shiong R, French L, Kaplan DR, Miller FD, Paus T. Axon diameter and axonal transport: In vivo and in vitro effects of androgens. Neuroimage 2015; 115:191-201. [PMID: 25956809 DOI: 10.1016/j.neuroimage.2015.04.048] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 01/05/2023] Open
Abstract
Testosterone is a sex hormone involved in brain maturation via multiple molecular mechanisms. Previous human studies described age-related changes in the overall volume and structural properties of white matter during male puberty. Based on this work, we have proposed that testosterone may induce a radial growth of the axon and, possibly, modulate axonal transport. In order to determine whether this is the case we have used two different experimental approaches. With electron microscopy, we have evaluated sex differences in the structural properties of axons in the corpus callosum (splenium) of young rats, and tested consequences of castration carried out after weaning. Then we examined in vitro the effect of the non-aromatizable androgen Mibolerone on the structure and bidirectional transport of wheat-germ agglutinin vesicles in the axons of cultured sympathetic neurons. With electron microscopy, we found robust sex differences in axonal diameter (males>females) and g ratio (males>females). Removal of endogenous testosterone by castration was associated with lower axon diameter and lower g ratio in castrated (vs. intact) males. In vitro, Mibolerone influenced the axonal transport in a time- and dose-dependent manner, and increased the axon caliber as compared with vehicle-treated neurons. These findings are consistent with the role of testosterone in shaping the axon by regulating its radial growth, as predicted by the initial human studies.
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Affiliation(s)
- M Pesaresi
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - R Soon-Shiong
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - L French
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - D R Kaplan
- Program in Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - F D Miller
- Program in Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - T Paus
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada.
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Christensen M, Pearce S, Ledbetter N, Warren D, Clark G, Tresco P. The foreign body response to the Utah Slant Electrode Array in the cat sciatic nerve. Acta Biomater 2014; 10:4650-4660. [PMID: 25042798 DOI: 10.1016/j.actbio.2014.07.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 06/17/2014] [Accepted: 07/12/2014] [Indexed: 01/09/2023]
Abstract
As the field of neuroprosthetic research continues to grow, studies describing the foreign body reaction surrounding chronic indwelling electrodes or microelectrode arrays will be critical for assessing biocompatibility. Of particular importance is the reaction surrounding penetrating microelectrodes that are used to stimulate and record from peripheral nerves used for prosthetic control, where such studies on axially penetrating electrodes are limited. Using the Utah Slant Electrode Array and a variety of histological methods, we investigated the foreign body response to the implanted array and its surrounding silicone cuff over long indwelling periods in the cat sciatic nerve. We observed that implanted nerves were associated with increased numbers of activated macrophages at the implant site, as well as distal to the implant, at all time points examined, with the longest observation being 350 days after implantation. We found that implanted cat sciatic nerves undergo a compensatory regenerative response after the initial injury that is accompanied by shifts in nerve fiber composition toward nerve fibers of smaller diameter and evidence of axons growing around microelectrode shafts. Nerve fibers located in fascicles that were not penetrated by the array or were located more than a few hundred microns from the implant appeared normal when examined over the course of a year-long indwelling period.
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42
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Statistical physics approach to quantifying differences in myelinated nerve fibers. Sci Rep 2014; 4:4511. [PMID: 24676146 PMCID: PMC3968487 DOI: 10.1038/srep04511] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/12/2014] [Indexed: 11/08/2022] Open
Abstract
We present a new method to quantify differences in myelinated nerve fibers. These differences range from morphologic characteristics of individual fibers to differences in macroscopic properties of collections of fibers. Our method uses statistical physics tools to improve on traditional measures, such as fiber size and packing density. As a case study, we analyze cross–sectional electron micrographs from the fornix of young and old rhesus monkeys using a semi-automatic detection algorithm to identify and characterize myelinated axons. We then apply a feature selection approach to identify the features that best distinguish between the young and old age groups, achieving a maximum accuracy of 94% when assigning samples to their age groups. This analysis shows that the best discrimination is obtained using the combination of two features: the fraction of occupied axon area and the effective local density. The latter is a modified calculation of axon density, which reflects how closely axons are packed. Our feature analysis approach can be applied to characterize differences that result from biological processes such as aging, damage from trauma or disease or developmental differences, as well as differences between anatomical regions such as the fornix and the cingulum bundle or corpus callosum.
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Stiefel KM, Torben-Nielsen B, Coggan JS. Proposed evolutionary changes in the role of myelin. Front Neurosci 2013; 7:202. [PMID: 24265603 PMCID: PMC3820973 DOI: 10.3389/fnins.2013.00202] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 10/13/2013] [Indexed: 12/30/2022] Open
Abstract
Myelin is the multi-layered lipid sheet periodically wrapped around neuronal axons. It is most frequently found in vertebrates. Myelin allows for saltatory action potential (AP) conduction along axons. During this form of conduction, the AP travels passively along the myelin-covered part of the axon, and is recharged at the intermittent nodes of Ranvier. Thus, myelin can reduce the energy load needed and/or increase the speed of AP conduction. Myelin first evolved during the Ordovician period. We hypothesize that myelin's first role was mainly energy conservation. During the later "Mesozoic marine revolution," marine ecosystems changed toward an increase in marine predation pressure. We hypothesize that the main purpose of myelin changed from energy conservation to conduction speed increase during this Mesozoic marine revolution. To test this hypothesis, we optimized models of myelinated axons for a combination of AP conduction velocity and energy efficiency. We demonstrate that there is a trade-off between these objectives. We then compared the simulation results to empirical data and conclude that while the data are consistent with the theory, additional measurements are necessary for a complete evaluation of the proposed hypothesis.
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Affiliation(s)
- Klaus M. Stiefel
- The MARCS Institute, Sydney, University of Western SydneyNSW, Australia
| | - Benjamin Torben-Nielsen
- The Blue Brain Project, Ecole Polytechnique Fédérale de LausanneLausanne, Switzerland
- Department of Neurobiology, Hebrew University of Jerusalem, Edmond J. Safra CampusJerusalem, Israel
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44
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Affiliation(s)
- Beat Ludin
- Friedrich Miescher Institute, Basel, Switzerland
| | - Andrew Matus
- Friedrich Miescher Institute, Basel, Switzerland
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45
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Abstract
Electrical signals can be recorded using long-term implanted nerve cuff electrodes in human peripheral nerves. Reliable detection of sensory nerve signals is essential if such signals are to be of use in sensory-based functional electrical stimulation neural prosthetics as a replacement for artificial sensors (switches, strain gauges, etc.). In this review, the signal characteristics of the sensors, the nerve interface, signal processing, and an example of human application to restore motor functions are described.
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Affiliation(s)
- T Sinkjaer
- Center for Sensory-Motor Interaction, Department of Medical Informatics and Image Analysis, Aalborg University, Denmark
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46
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A quantitative evaluation of gross versus histologic neuroma formation in a rabbit forelimb amputation model: potential implications for the operative treatment and study of neuromas. J Brachial Plex Peripher Nerve Inj 2011; 6:8. [PMID: 21992517 PMCID: PMC3207865 DOI: 10.1186/1749-7221-6-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 10/13/2011] [Indexed: 11/28/2022] Open
Abstract
Background Surgical treatment of neuromas involves excision of neuromas proximally to the level of grossly "normal" fascicles; however, proximal changes at the axonal level may have both functional and therapeutic implications with regard to amputated nerves. In order to better understand the retrograde "zone of injury" that occurs after nerve transection, we investigated the gross and histologic changes in transected nerves using a rabbit forelimb amputation model. Methods Four New Zealand White rabbits underwent a forelimb amputation with transection and preservation of the median, radial, and ulnar nerves. After 8 weeks, serial sections of the amputated nerves were then obtained in a distal-to-proximal direction toward the brachial plexus. Quantitative histomorphometric analysis was performed on all nerve specimens. Results All nerves demonstrated statistically significant increases in nerve cross-sectional area between treatment and control limbs at the distal nerve end, but these differences were not observed 10 mm more proximal to the neuroma bulb. At the axonal level, an increased number of myelinated fibers were seen at the distal end of all amputated nerves. The number of myelinated fibers progressively decreased in proximal sections, normalizing at 15 mm proximally, or the level of the brachial plexus. The cross-sectional area of myelinated fibers was significantly decreased in all sections of the treatment nerves, indicating that atrophic axonal changes proceed proximally at least to the level of the brachial plexus. Conclusions Morphologic changes at the axonal level extend beyond the region of gross neuroma formation in a distal-to-proximal fashion after nerve transection. This discrepancy between gross and histologic neuromas signifies the need for improved standardization among neuroma models, while also providing a fresh perspective on how we should view neuromas during peripheral nerve surgery.
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Tomassini V, Jbabdi S, Kincses ZT, Bosnell R, Douaud G, Pozzilli C, Matthews PM, Johansen-Berg H. Structural and functional bases for individual differences in motor learning. Hum Brain Mapp 2011; 32:494-508. [PMID: 20533562 PMCID: PMC3674543 DOI: 10.1002/hbm.21037] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 01/15/2010] [Accepted: 02/01/2010] [Indexed: 11/12/2022] Open
Abstract
People vary in their ability to learn new motor skills. We hypothesize that between-subject variability in brain structure and function can explain differences in learning. We use brain functional and structural MRI methods to characterize such neural correlates of individual variations in motor learning. Healthy subjects applied isometric grip force of varying magnitudes with their right hands cued visually to generate smoothly-varying pressures following a regular pattern. We tested whether individual variations in motor learning were associated with anatomically colocalized variations in magnitude of functional MRI (fMRI) signal or in MRI differences related to white and grey matter microstructure. We found that individual motor learning was correlated with greater functional activation in the prefrontal, premotor, and parietal cortices, as well as in the basal ganglia and cerebellum. Structural MRI correlates were found in the premotor cortex [for fractional anisotropy (FA)] and in the cerebellum [for both grey matter density and FA]. The cerebellar microstructural differences were anatomically colocalized with fMRI correlates of learning. This study thus suggests that variations across the population in the function and structure of specific brain regions for motor control explain some of the individual differences in skill learning. This strengthens the notion that brain structure determines some limits to cognitive function even in a healthy population. Along with evidence from pathology suggesting a role for these regions in spontaneous motor recovery, our results also highlight potential targets for therapeutic interventions designed to maximize plasticity for recovery of similar visuomotor skills after brain injury.
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Affiliation(s)
- Valentina Tomassini
- Oxford Centre for Functional MRI of the Brain, Department of Clinical Neurology, University of Oxford, United Kingdom.
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da Costa RFM, Martinez AMB, Ferreira ST. 2,4-Dinitrophenol blocks neurodegeneration and preserves sciatic nerve function after trauma. J Neurotrauma 2010; 27:829-41. [PMID: 20143955 DOI: 10.1089/neu.2009.1189] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Preventing the harm caused by nerve degeneration is a major challenge in neurodegenerative diseases and in various forms of trauma to the nervous system. The aim of the current work was to investigate the effects of systemic administration of 2,4-dinitrophenol (DNP), a compound with newly recognized neuroprotective properties, on sciatic-nerve degeneration following a crush injury. Sciatic-nerve injury was induced by unilateral application of an aneurysm clip. Four groups of mice were used: uninjured, injured treated with vehicle (PBS), injured treated with two intraperitoneal doses of DNP (0.06 mg DNP/kg every 24 h), and injured treated with four doses of DNP (every 12 h). Animals were sacrificed 48 h post injury and both injured and uninjured (contralateral) sciatic nerves were processed for light and electron microscopy. Morphometric, ultrastructural, and immunohistochemical analysis of injured nerves established that DNP prevented axonal degeneration, blocked cytoskeletal disintegration, and preserved the immunoreactivity of amyloid precursor protein (APP) and Neuregulin 1 (Nrg1), proteins implicated in neuronal survival and myelination. Functional tests revealed preservation of limb function following injury in DNP-treated animals. Results indicate that DNP prevents nerve degeneration and suggest that it may be a useful small-molecule adjuvant in the development of novel therapeutic approaches in nerve injury.
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Affiliation(s)
- Rodrigo F Madeiro da Costa
- Programa de Bioquimica e Biofisica Celular, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Della-Maggiore V, Scholz J, Johansen-Berg H, Paus T. The rate of visuomotor adaptation correlates with cerebellar white-matter microstructure. Hum Brain Mapp 2010; 30:4048-53. [PMID: 19507158 DOI: 10.1002/hbm.20828] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Convergent experimental evidence points to the cerebellum as a key neural structure mediating adaptation to visual and proprioceptive perturbations. In a previous study, we have shown that activity in the anterior cerebellum varies with the rate of learning, with fast learners exhibiting more activity in this region than slow learners. Here, we investigated whether this variability in behavior may partly reflect inter-individual differences in the structural properties of cerebellar white-matter output tracts. For this purpose, we used diffusion-weighted magnetic resonance imaging to estimate fractional anisotropy (FA), and correlated the FA with the rate of adaptation to an optical rotation in 11 subjects. We found that FA in a region consistent with the superior cerebellar peduncle (SCP), containing fibers connecting the cerebellar cortex with motor and premotor cortex, was positively correlated with the rate of adaptation but not with the general level of performance or the initial deviation. The same pattern was observed in a region of the lateral posterior cerebellum. In contrast, FA in the angular gyrus of the posterior parietal cortex correlated positively both with the rate of adaptation and the overall level of performance. Our results show that the rate of learning a visuomotor task is associated with FA of cerebellar pathways.
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Affiliation(s)
- Valeria Della-Maggiore
- Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, C1121ABG, Argentina.
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50
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Hoffer JA, Kallesøe K. How to Use Nerve Cuffs to Stimulate, Record or Modulate Neural Activity. ACTA ACUST UNITED AC 2009. [DOI: 10.1201/9781420039054.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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