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Xu R, Ren L, Zhang X, Qian Z, Wu J, Liu J, Li Y, Ren L. Non-invasive in vivo study of morphology and mechanical properties of the median nerve. Front Bioeng Biotechnol 2024; 12:1329960. [PMID: 38665817 PMCID: PMC11043530 DOI: 10.3389/fbioe.2024.1329960] [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: 10/30/2023] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
The current literature studied the median nerve (MN) at specific locations during joint motions. As only a few particular parts of the nerve are depicted, the relevant information available is limited. This experiment investigated the morphological and biomechanical properties of the MN. The effects of the shoulder and wrist motions on MN were explored as well. Eight young healthy female individuals were tested with two-dimensional ultrasound and shear wave elastography (SWE). The morphological and biomechanical properties were examined in limb position 1, with the wrist at the neutral position, the elbow extended at 180°, and the shoulder abducted at 60°. In addition, the experiment assessed the differences among the wrist, forearm, elbow, and upper arm with Friedman's test and Bonferroni post hoc analysis. Two groups of limb positions were designed to explore the effects of shoulder movements (shoulder abducted at 90° and 120°) and wrist movements (wrist extended at 45° and flexed at 45°) on the thickness and Young's modulus. Differences among the distributions of five limb positions were tested as well. The ICC3, 1 values for thickness and Young's modulus were 0.976 and 0.996, respectively. There were differences among the MN thicknesses of four arm locations in limb position 1, while Young's modulus was higher at the elbow and wrist than at the forearm and upper arm. Compared to limb position 1, only limb position 4 had an effect on MN thickness at the wrist. Both shoulder and wrist motions affected MN Young's modulus, and the stiffness variations at typical locations all showed a downward trend proximally in all. The distributions of MN thickness and Young's modulus showed fold line patterns but differed at the wrist and the pronator teres. The MN in the wrist is more susceptible to limb positions, and Young's modulus is sensitive to nerve changes and is more promising for the early diagnosis of neuropathy.
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Affiliation(s)
- Ruixia Xu
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
| | - Lei Ren
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
| | - Xiao Zhang
- School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Zhihui Qian
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
| | - Jianan Wu
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
| | - Jing Liu
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
| | - Ying Li
- Editorial Department of Journal of Bionic Engineering, Jilin University, Changchun, China
| | - Luquan Ren
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China
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Sheehan GD, Martin MK, Young VA, Powell R, Bhattacharjee A. Thermal hyperalgesia and dynamic weight bearing share similar recovery dynamics in a sciatic nerve entrapment injury model. NEUROBIOLOGY OF PAIN 2021; 10:100079. [PMID: 34917858 PMCID: PMC8665403 DOI: 10.1016/j.ynpai.2021.100079] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/01/2021] [Accepted: 12/01/2021] [Indexed: 11/28/2022]
Abstract
The sciatic nerve cuff model of neuropathic pain exhibits pain recovery. Thermal hyperalgesia and dynamic weight bearing display similar pain recovery profiles, whereas mechanical allodynia persists. Dynamic weight bearing is a non-reflexive, pain assessment of ongoing pain during nerve entrapment.
Chronic constriction injuries (CCI) of the sciatic nerve are widely used nerve entrapment animal models of neuropathic pain. Two common pain behaviors observed following CCI are thermal hyperalgesia and mechanical allodynia, measured by the Hargreaves and von Frey tests, respectively. While thermal hyperalgesia tends to recover by 30 days, mechanical allodynia can persist for many more months thereafter. Consequently, mechanical allodynia has been used extensively as a measure of ‘chronic pain’ focusing on the circuitry changes that occur within the spinal cord. Here, using the sciatic nerve cuff variant of CCI in mice, we propose that in contrast to these evoked measures of nociceptive hypersensitivity, dynamic weight bearing provides a more clinically relevant behavioral measure for ongoing pain during nerve injury. We found that the effect of sciatic nerve cuff on the ratio of weight bearing by the injured relative to uninjured hindlimbs more closely resembled that of thermal hyperalgesia, following a trend toward recovery by 30 days. We also found an increase in the percent of body weight bearing by the contralateral paw that is not seen in the previously tested behaviors. These results demonstrate that dynamic weight bearing is a reliable measure of non-evoked neuropathic pain and suggest that thermal hyperalgesia, rather than mechanical allodynia, provides a proxy measure for nerve entrapment-induced ongoing pain.
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Affiliation(s)
- Garrett D. Sheehan
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Molly K. Martin
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Violet A. Young
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Rasheen Powell
- Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Arin Bhattacharjee
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
- Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
- Corresponding author at: Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York USA.
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Yeoh S, Warner WS, Eli I, Mahan MA. Rapid-stretch injury to peripheral nerves: comparison of injury models. J Neurosurg 2020; 135:893-903. [PMID: 33157535 DOI: 10.3171/2020.5.jns193448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 05/13/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Traditional animal models of nerve injury use controlled crush or transection injuries to investigate nerve regeneration; however, a more common and challenging clinical problem involves closed traction nerve injuries. The authors have produced a precise traction injury model and sought to examine how the pathophysiology of stretch injuries compares with that of crush and transection injuries. METHODS Ninety-five late-adolescent (8-week-old) male mice underwent 1 of 7 injury grades or a sham injury (n > 10 per group): elastic stretch, inelastic stretch, stretch rupture, crush, primary coaptation, secondary coaptation, and critical gap. Animals underwent serial neurological assessment with sciatic function index, tapered beam, and von Frey monofilament testing for 48 days after injury, followed by trichrome and immunofluorescent nerve histology and muscle weight evaluation. RESULTS The in-continuity injuries, crush and elastic stretch, demonstrated different recovery profiles, with more severe functional deficits after crush injury than after elastic stretch immediately following injury (p < 0.05). However, animals with either injury type returned to baseline performance in all neurological assessments, accompanied by minimal change in nerve histology. Inelastic stretch, a partial discontinuity injury, produced more severe neurological deficits, incomplete return of function, 47% ± 9.1% (mean ± SD) reduction of axon counts (p < 0.001), and partial neuroma formation within the nerve. Discontinuity injuries, including immediate and delayed nerve repair, stretch rupture, and critical gap, manifested severe, long-term neurological deficits and profound axonal loss, coupled with intraneural scar formation. Although repaired nerves demonstrated axon regeneration across the gap, rupture and critical gap injuries demonstrated negligible axon crossing, despite rupture injuries having healed into continuity. CONCLUSIONS Stretch-injured nerves present unique pathology and functional deficits compared with traditional nerve injury models. Because of the profound neuroma formation, stretch injuries represent an opportunity to study the pathophysiology associated with clinical injury mechanisms. Further validation for comparison with human injuries will require evaluation in a large-animal model.
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Warner WS, Yeoh S, Light A, Zhang J, Mahan MA. Rapid-Stretch Injury to Peripheral Nerves: Histologic Results. Neurosurgery 2020; 86:437-445. [PMID: 31140562 DOI: 10.1093/neuros/nyz194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/11/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Although most severe peripheral nerve injuries result from high-speed mechanisms, there is no laboratory model to replicate this clinical condition. OBJECTIVE To qualitatively and quantitatively describe microanatomical injury of rapid stretch. METHODS The sciatic nerves of 36 Sprague-Dawley rats were subjected to rapid-stretch nerve injury, using fixed-direction strain produced via constrained weight drop applied to an intact nerve. Nerve injury severity was categorized by biomechanical parameters. Injury to nerve microarchitecture was quantified with serial longitudinal sectioning, with specific focus on the endoneurium, perineurium, and epineurium. RESULTS Four grades of stretch injury severity were determined by mathematical cluster analysis: sham, elastic stretch, inelastic stretch, and stretch rupture. Two patterns of injury to endoneurial architecture were quantified: loss of fiber undulation (straightened fibers) and rupturing of individual fibers ("microruptures"). Straightening of nerve fibers was the earliest accommodation to stretch injury and accounted for elongation during elastic stretch. Microruptures were distributed along the length of the nerve and were more severe and involved greater volume of the nerve at higher biomechanical severity. Epineurium and perineurium disruption increased in frequency with progressive injury severity, yet did not predict transition from one injury grade to another (P = .3), nor was it a hallmark of severe injury. Conversely, accumulation of microruptures provided strong correlation to nerve injury severity (Pearson's R = .9897) and progression to mechanical failure. CONCLUSION Nerve architecture is injured in a graded fashion during stretch injury, which likely reflects tissue biomechanics. This study suggests new considerations in the theoretical framework of nerve stretch trauma.
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Affiliation(s)
- Wesley S Warner
- Department of Neurosurgery, Clinical Neurosciences Center, The University of Utah, Salt Lake City, Utah
| | - Stewart Yeoh
- Department of Neurosurgery, Clinical Neurosciences Center, The University of Utah, Salt Lake City, Utah
| | - Alan Light
- Department of Anesthesiology, The University of Utah, Salt Lake City, Utah
| | - Jie Zhang
- Department of Anesthesiology, The University of Utah, Salt Lake City, Utah
| | - Mark A Mahan
- Department of Neurosurgery, Clinical Neurosciences Center, The University of Utah, Salt Lake City, Utah
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Mahan MA, Yeoh S, Monson K, Light A. Rapid Stretch Injury to Peripheral Nerves: Biomechanical Results. Neurosurgery 2020; 85:E137-E144. [PMID: 30383240 DOI: 10.1093/neuros/nyy423] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 08/08/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Although most adult brachial plexus injuries result from high-speed mechanisms, no laboratory model has been created to mimic rapid-stretch nerve injuries. Understanding the biomechanical response of nerves to rapid stretch is essential to understanding clinical injury patterns and developing models that mimic the clinical scenario. OBJECTIVE To assess the influence of rate, loading direction, and excursion of stretch injuries on the biomechanical properties of peripheral nerves. METHODS The sciatic nerves of 138 Sprague-Dawley rats were dissected and subjected to rapid- and slow-stretch methods. Maximal nerve strain, persistent deformation, regional strain variation, and location of nerve failure were recorded. RESULTS Nerve rupture was primarily determined by weight-drop momentum >1 N/sec (odds ratio = 27.8, P < .0001), suggesting a threshold condition. Loading direction strongly determined maximal strain at rupture (P = .028); pull along the nerve axis resulted in nerve rupture at lower strain than orthogonal loading. Regional variations in nerve compliance and rupture location correlated with anatomic zones. Nerve branch anatomy was the largest contributing factor on maximum strain and rupture location. Rapidly stretched nerves are characterized by a zone of elastic recovery, followed by inelastic response at increasing strain, and finally rupture. CONCLUSION The large variation in previous results for nerve strain at rupture can be attributed to different testing conditions and is largely due to loading direction or segment of nerve tested, which has significant clinical implications. Nerve stretch injuries do not reflect a continuous variability to applied force but instead fall into biomechanical patterns of elastic, inelastic, and rupture injuries.
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Affiliation(s)
- Mark A Mahan
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah
| | - Stewart Yeoh
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah
| | - Ken Monson
- Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah.,Department of Bioengineering, University of Utah, Salt Lake City, Utah
| | - Alan Light
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
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Umansky D, Midha R. Commentary: Rapid-Stretch Injury to Peripheral Nerves: Histologic Results. Neurosurgery 2020; 86:E333-E334. [PMID: 31157886 DOI: 10.1093/neuros/nyz196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 02/11/2019] [Indexed: 11/12/2022] Open
Affiliation(s)
- Daniel Umansky
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Rajiv Midha
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
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Alvey LM, Jones JFX, Tobin-O'Brien C, Pickering M. Bands of Fontana are caused exclusively by the sinusoidal path of axons in peripheral nerves and predict axon path; evidence from rodent nerves and physical models. J Anat 2018; 234:165-178. [PMID: 30426493 DOI: 10.1111/joa.12910] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2018] [Indexed: 11/28/2022] Open
Abstract
The precise cause of the bands of Fontana, striations on peripheral nerves visible to the naked eye, has been the subject of debate for hundreds of years. Some researchers have described them as reflecting the sinuous course of nerve fibres passing through nerves, and others have proposed that endoneurial collagen and sheaths surrounding nerves play a role in their appearance. We hypothesised that the bands are caused exclusively by reflection of light from the surfaces of nerve fibres travelling in phase in sinusoidal waveforms through peripheral nerves. We aligned images of obliquely illuminated nerves with confocal images of axons in those nerves, and the numbers and positions of the bands precisely matched the axonal waves. We also developed three-dimensional models of nerves with representations of the sinusoidal path of axons at their surface. We observed patterns resembling the bands of Fontana when these models were obliquely illuminated. This provides evidence that the bands of Fontana can be caused by light reflected sinusoidal path of axons alone. We subsequently describe a mechanism of band production based on our observations of both nerves and models. We report that smaller diameter nerves such as phrenic nerves and distal branches of sciatic nerves have shorter band intervals than larger nerves, such as proximal trunks of sciatic nerves, and that shorter band intervals correlate with longer axons per unit length of nerve, which suggests a greater tolerance to stretch. Inspection of banding patterns on peripheral nerves may permit prediction of axon length within nerves, and assist in the interpretation of nerve conduction data, especially in diseases where axon path has become altered.
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Affiliation(s)
- Luke M Alvey
- School of Medicine, University College Dublin, Dublin, Ireland
| | - James F X Jones
- School of Medicine, University College Dublin, Dublin, Ireland
| | | | - Mark Pickering
- School of Medicine, University College Dublin, Dublin, Ireland
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Kakkar LS, Bennett OF, Siow B, Richardson S, Ianuş A, Quick T, Atkinson D, Phillips JB, Drobnjak I. Low frequency oscillating gradient spin-echo sequences improve sensitivity to axon diameter: An experimental study in viable nerve tissue. Neuroimage 2018; 182:314-328. [DOI: 10.1016/j.neuroimage.2017.07.060] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 07/27/2017] [Accepted: 07/28/2017] [Indexed: 10/19/2022] Open
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Belin S, Zuloaga KL, Poitelon Y. Influence of Mechanical Stimuli on Schwann Cell Biology. Front Cell Neurosci 2017; 11:347. [PMID: 29209171 PMCID: PMC5701625 DOI: 10.3389/fncel.2017.00347] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/19/2017] [Indexed: 12/05/2022] Open
Abstract
Schwann cells are the glial cells of the peripheral nervous system (PNS). They insulate axons by forming a specialized extension of plasma membrane called the myelin sheath. The formation of myelin is essential for the rapid saltatory propagation of action potentials and to maintain the integrity of axons. Although both axonal and extracellular matrix (ECM) signals are necessary for myelination to occur, the cellular and molecular mechanisms regulating myelination continue to be elucidated. Schwann cells in peripheral nerves are physiologically exposed to mechanical stresses (i.e., tensile, compressive and shear strains), occurring during development, adulthood and injuries. In addition, there is a growing body of evidences that Schwann cells are sensitive to the stiffness of their environment. In this review, we detail the mechanical constraints of Schwann cells and peripheral nerves. We explore the regulation of Schwann cell signaling pathways in response to mechanical stimulation. Finally, we provide a comprehensive overview of the experimental studies addressing the mechanobiology of Schwann cells. Understanding which mechanical properties can interfere with the cellular and molecular biology of Schwann cell during development, myelination and following injuries opens new insights in the regulation of PNS development and treatment approaches in peripheral neuropathies.
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Affiliation(s)
- Sophie Belin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Kristen L. Zuloaga
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Yannick Poitelon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
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Power BJ, O'reilly G, Murphy R, Murphy KJ, Pickering M, Jones JFX. Normal nerve striations are altered in the trembler-J mouse, a model of Charcot-Marie-Tooth disease. Muscle Nerve 2015; 51:246-52. [PMID: 24890015 DOI: 10.1002/mus.24303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 05/21/2014] [Accepted: 05/28/2014] [Indexed: 11/09/2022]
Abstract
INTRODUCTION This study was initiated because it was noted that the peripheral nerves of Trembler-J mice (a model of human Charcot-Marie-Tooth disease) appear to lack normal striations. METHODS We performed confocal microscopy of whole sciatic nerves and tested the effect of axial stress on impulse conduction. RESULTS We found that the axons of mutant mice were longer than those of the wild-type (1.55 mm of axon/mm length of nerve vs. 1.28 mm/mm respectively). This axonal elongation altered the helical nerve striations (bands of Fontana). As nerves were stretched axially, the conduction distance became correspondingly shorter. The effect on latency was significantly greater in the more coiled nerves of Trembler-J mice (P = 0.038). CONCLUSIONS The finding that mice with a mutated peripheral myelin protein 22 (PMP22) possess excessively long axons may be related to the excess Schwann cell numbers found in this disorder.
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Affiliation(s)
- Bridget J Power
- School of Medicine and Medical Science, University College Dublin, Dublin 4, Ireland
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Taffetani M, Ciarletta P. Elastocapillarity can control the formation and the morphology of beads-on-string structures in solid fibers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:032413. [PMID: 25871129 DOI: 10.1103/physreve.91.032413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Indexed: 06/04/2023]
Abstract
Beads-on-string patterns have been experimentally observed in solid cylinders for a wide range of material properties and structural lengths, from millimetric soft gels to nanometric hard fibers. In this work, we combine theoretical analysis and numerical tools to investigate the formation and nonlinear dynamics of such beaded structures. We show that this morphological transition is driven by elastocapillarity, i.e., a complex interplay between the effects of surface tension and bulk elasticity. Unlike buckling or wrinkling, the presence of an axial elongation is found here to favor the onset of fiber beading, in agreement with existing experimental results on electrospun fibers, hydrogels, and nerves. Our results also prove that the applied stretch can be used in fabrication techniques to control the morphology of the emerging beads-on-string patterns. Such quantitative predictions open the way for several applications, from tissue engineering to the design of stretchable electronics and the microfabrication of functionalized surfaces.
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Affiliation(s)
- M Taffetani
- MOX, Politecnico di Milano and Fondazione CEN-Centro Europeo di Nanomedicina, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
| | - P Ciarletta
- MOX, Politecnico di Milano and Fondazione CEN-Centro Europeo di Nanomedicina, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
- CNRS and Sorbonne Universités, Université Paris 6, Institut Jean le Rond d'Alembert, UMR 7190, 4 place Jussieu case 162, 75005 Paris, France
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Love JM, Chuang TH, Lieber RL, Shah SB. Nerve strain correlates with structural changes quantified by fourier analysis. Muscle Nerve 2013; 48:433-5. [DOI: 10.1002/mus.23809] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2013] [Indexed: 11/09/2022]
Affiliation(s)
- James M. Love
- Fischell Department of Bioengineering; University of Maryland; College Park; Maryland; USA
| | - Ting-Hsien Chuang
- Departments of Orthopedic Surgery and Bioengineering; University of California; 9500 Gilman Drive, Mail Code 0863; San Diego, La Jolla; California; 92093; USA
| | - Richard L. Lieber
- Departments of Orthopedic Surgery and Bioengineering; University of California; 9500 Gilman Drive, Mail Code 0863; San Diego, La Jolla; California; 92093; USA
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Merolli A, Mingarelli L, Rocchi L. A more detailed mechanism to explain the "bands of Fontana" in peripheral nerves. Muscle Nerve 2012; 46:540-7. [PMID: 22987695 DOI: 10.1002/mus.23422] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION In 1779, Fontana identified transverse and oblique bands along peripheral nerves. Subsequent studies pointed alternatively to endoneural or perineural components as the cause. Our aim was to clarify these conflicting findings. METHODS Recoiling of the bands of Fontana was video-recorded in the rat sciatic nerve. Computer-assisted design (CAD) software was used to model the nerve by interference figures. RESULTS In vivo microdissection showed distinctive, black-and-white, closely packed bands in the perineurium, which differed from the widely spaced, translucent, dark/pale gray, staggered bands in the endoneurium. CAD merging of these 2 patterns produced images resembling the bands observed in vivo. CONCLUSIONS Two repetitive structures with different characteristics, 1 in the perineurium and the other in the endoneurium, merge to give the appearance of these bands.
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Affiliation(s)
- Antonio Merolli
- Clinica Ortopedica, Università Cattolica, Largo Gemelli 8, I-00168 Roma, Italy.
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Islam MS, Oliveira MC, Wang Y, Henry FP, Randolph MA, Park BH, de Boer JF. Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:056012. [PMID: 22612135 PMCID: PMC3382351 DOI: 10.1117/1.jbo.17.5.056012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury.
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Affiliation(s)
- M. Shahidul Islam
- University of California Riverside, Department of Bioengineering, Riverside, California 92521
| | - Michael C. Oliveira
- University of California Riverside, Department of Bioengineering, Riverside, California 92521
| | - Yan Wang
- University of California Riverside, Department of Bioengineering, Riverside, California 92521
| | | | - Mark A. Randolph
- Massachusetts General Hospital, Plastic Surgery Research Laboratory, Massachusetts 02114
| | - B. Hyle Park
- University of California Riverside, Department of Bioengineering, Riverside, California 92521
- Address all correspondence to: B. Hyle Park, University of California Riverside, Department of Bioengineering, Riverside, California 92521. Tel.: +1 9518275188; Fax: +1 9518276416; E-mail:
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Nilsson M, Lätt J, Ståhlberg F, van Westen D, Hagslätt H. The importance of axonal undulation in diffusion MR measurements: a Monte Carlo simulation study. NMR IN BIOMEDICINE 2012; 25:795-805. [PMID: 22020832 DOI: 10.1002/nbm.1795] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 08/31/2011] [Accepted: 09/02/2011] [Indexed: 05/12/2023]
Abstract
Many axons follow wave-like undulating courses. This is a general feature of extracranial nerve segments, but is also found in some intracranial nervous tissue. The importance of axonal undulation has previously been considered, for example, in the context of biomechanics, where it has been shown that posture affects undulation properties. However, the importance of axonal undulation in the context of diffusion MR measurements has not been investigated. Using an analytical model and Monte Carlo simulations of water diffusion, this study compared undulating and straight axons in terms of diffusion propagators, diffusion-weighted signal intensities and parameters derived from diffusion tensor imaging, such as the mean diffusivity (MD), the eigenvalues and the fractional anisotropy (FA). All parameters were strongly affected by the presence of undulation. The diffusivity perpendicular to the undulating axons increased with the undulation amplitude, thus resembling that of straight axons with larger diameters. Consequently, models assuming straight axons for the estimation of the axon diameter from diffusion MR measurements might overestimate the diameter if undulation is present. FA decreased from approximately 0.7 to 0.5 when axonal undulation was introduced into the simulation model structure. Our results indicate that axonal undulation may play a role in diffusion measurements when investigating, for example, the optic and sciatic nerves and the spinal cord. The simulations also demonstrate that the stretching or compression of neuronal tissue comprising undulating axons alters the observed water diffusivity, suggesting that posture may be of importance for the outcome of diffusion MRI measurements.
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Affiliation(s)
- Markus Nilsson
- Department of Medical Radiation Physics, Lund University, Lund, Sweden.
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Neurite beading is sufficient to decrease the apparent diffusion coefficient after ischemic stroke. Proc Natl Acad Sci U S A 2010; 107:14472-7. [PMID: 20660718 DOI: 10.1073/pnas.1004841107] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Diffusion-weighted MRI (DWI) is a sensitive and reliable marker of cerebral ischemia. Within minutes of an ischemic event in the brain, the microscopic motion of water molecules measured with DWI, termed the apparent diffusion coefficient (ADC), decreases within the infarcted region. However, although the change is related to cell swelling, the precise pathological mechanism remains elusive. We show that focal enlargement and constriction, or beading, in axons and dendrites are sufficient to substantially decrease ADC. We first derived a biophysical model of neurite beading, and we show that the beaded morphology allows a larger volume to be encompassed within an equivalent surface area and is, therefore, a consequence of osmotic imbalance after ischemia. The DWI experiment simulated within the model revealed that intracellular ADC decreased by 79% in beaded neurites compared with the unbeaded form. To validate the model experimentally, excised rat sciatic nerves were subjected to stretching, which induced beading but did not cause a bulk shift of water into the axon (i.e., swelling). Beading-induced changes in cell-membrane morphology were sufficient to significantly hinder water mobility and thereby decrease ADC, and the experimental measurements were in excellent agreement with the simulated values. This is a demonstration that neurite beading accurately captures the diffusion changes measured in vivo. The results significantly advance the specificity of DWI in ischemia and other acute neurological injuries and will greatly aid the development of treatment strategies to monitor and repair damaged brain in both clinical and experimental settings.
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17
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Ochs S, Pourmand R, Si K, Friedman RN. Stretch of mammalian nerve
in vitro
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Effect on compound action potentials. J Peripher Nerv Syst 2008. [DOI: 10.1111/j.1529-8027.2000.00025.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sidney Ochs
- Department of Physiology/Biophysics,1 Department of Neurology,2 and Section of Neurological Surgery,3
Indiana University School of Medicine, Indianapolis
| | - Rahman Pourmand
- Department of Physiology/Biophysics,1 Department of Neurology,2 and Section of Neurological Surgery,3
Indiana University School of Medicine, Indianapolis
| | - Kenan Si
- Department of Physiology/Biophysics,1 Department of Neurology,2 and Section of Neurological Surgery,3
Indiana University School of Medicine, Indianapolis
| | - Richard N. Friedman
- Department of Physiology/Biophysics,1 Department of Neurology,2 and Section of Neurological Surgery,3
Indiana University School of Medicine, Indianapolis
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Li J, Shi R. Stretch-induced nerve conduction deficits in guinea pig ex vivo nerve. J Biomech 2007; 40:569-78. [PMID: 16674962 DOI: 10.1016/j.jbiomech.2006.02.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 02/10/2006] [Indexed: 10/24/2022]
Abstract
In the current communication, we characterized supraphysiologic elongations that elicited short-term nerve dysfunction. This was accomplished by assessing the electrophysiology of guinea pig tibial and peroneal nerves at predetermined elongation magnitudes. Results showed that a longitudinal supraphysiological stretch of lambda = 1.05 caused a 16% reduction in the mean compound action potential (CAP) amplitude. Upon relaxation to physiologic length, a full recovery in the CAP was observed. At lambda = 1.10, the CAP decreased by 50% with an 88% recovery after relaxation. For a supraphysiologic stretch of lambda = 1.20, severe conduction block with minimal acute recovery was observed. Latency also increased during periods of stretch and was proportional to the stretch magnitude. Additional studies showed some electrophysiological recovery during the sustained stretch phase. This attribute may be related to internal stress relaxation mechanisms. Since whole nerve elongations are averaged global deformations, we also used an incremental digital image correlation (DIC) technique to characterize the strain at the micro-tissue level. The DIC analysis revealed considerable heterogeneity in the planar strain field, with some regions exhibiting strains above the macroscale stretch. This non-uniformity in the strain map arises from structural inconsistencies of the nerve and we presume that zones of high local strain may translate into the observed conduction deficits.
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Affiliation(s)
- Jianming Li
- Weldon School of Biomedical Engineering and Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
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19
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Li J, Shi R. A device for the electrophysiological recording of peripheral nerves in response to stretch. J Neurosci Methods 2006; 154:102-8. [PMID: 16445987 DOI: 10.1016/j.jneumeth.2005.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 11/26/2005] [Accepted: 12/05/2005] [Indexed: 11/30/2022]
Abstract
The functional consequences of nervous tissue subjected to mechanical loads are of vital importance in successful clinical outcomes and in tissue engineered applications. In this paper, we developed a new ex vivo device that permitted the recording of nerve action potentials while the nerve was subjected to elongation. Experimental results showed guinea pig nerves to possess an inherent tolerance to mild stretch. The mean elongation at which the compound action potential (CAP) amplitude began to decrease was found to be 8.3 +/- 0.56%. The CAP response to stretch was immediate beyond this threshold. After 17.5 +/- 0.74% elongation, the CAP levels decreased to approximately 50% of its uninjured values. When allowed to relax, the CAP recovered almost completely within minutes. Based on the temporal scale of the CAP response and the presence of oxygen during testing, we conclude that the initial mechanism to CAP degradation cannot be ischemia. Since it is inherently difficult to study mechanical damage independent of hemodynamic factors in vivo, the developed model could be used to further elucidate the injury mechanisms of stretch-induced trauma. The design of the ex vivo chamber will also permit the administration and assessment of pharmacological agents on electrical conduction in various deformation conditions.
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Affiliation(s)
- Jianming Li
- Weldon School of Biomedical Engineering and Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
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20
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Topp KS, Boyd BS. Structure and biomechanics of peripheral nerves: nerve responses to physical stresses and implications for physical therapist practice. Phys Ther 2006; 86:92-109. [PMID: 16386065 DOI: 10.1093/ptj/86.1.92] [Citation(s) in RCA: 232] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The structural organization of peripheral nerves enables them to function while tolerating and adapting to stresses placed upon them by postures and movements of the trunk, head, and limbs. They are exposed to combinations of tensile, shear, and compressive stresses that result in nerve excursion, strain, and transverse contraction. The purpose of this appraisal is to review the structural and biomechanical modifications seen in peripheral nerves exposed to various levels of physical stress. We have followed the primary tenet of the Physical Stress Theory presented by Mueller and Maluf (2002), specifically, that the level of physical stress placed upon biological tissue determines the adaptive response of the tissue. A thorough understanding of the biomechanical properties of normal and injured nerves and the stresses placed upon them in daily activities will help guide physical therapists in making diagnoses and decisions regarding interventions.
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Affiliation(s)
- Kimberly S Topp
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, 1318 7th Ave, Box 0736, San Francisco, CA 94143-0736, USA.
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21
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Phillips JB, Smit X, De Zoysa N, Afoke A, Brown RA. Peripheral nerves in the rat exhibit localized heterogeneity of tensile properties during limb movement. J Physiol 2004; 557:879-87. [PMID: 15064329 PMCID: PMC1665165 DOI: 10.1113/jphysiol.2004.061804] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Peripheral nerves in the limbs stretch to accommodate changes in length during normal movement. The aim of this study was to determine how stretch is distributed along the nerve relative to local variations in mechanical properties. Deformation (strain) in joint and non-joint regions of rat median and sciatic nerves was measured in situ during limb movement using optical image analysis. In each nerve the strain was significantly greater in the joint rather than the non-joint regions (2-fold in the median nerve, 5- to 10-fold in the sciatic). In addition, this difference in strain was conserved in the median nerve ex vivo, demonstrating an in-built longitudinal heterogeneity of mechanical properties. Tensile testing of isolated samples of joint and non-joint regions of both nerves showed that joint regions were less stiff (more compliant) than their non-joint counterparts with joint: non-joint stiffness ratios of 0.5 +/- 0.07 in the median nerve, and 0.8 +/- 0.02 in the sciatic. However, no structural differences identified at the light microscope level in fascicular/non-fascicular tissue architecture between these two nerve regions could explain the observed tensile heterogeneity. This identification of localized functional heterogeneity in tensile properties is particularly important in understanding normal dynamic nerve physiology, provides clues to why peripheral nerve repair outcomes are variable, and suggests potential novel therapeutic targets.
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Affiliation(s)
- J B Phillips
- Tissue Repair and Engineering Centre, University College London, UK.
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22
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Schnabel V, Struijk JJ. Magnetic and electrical stimulation of undulating nerve fibres: a simulation study. Med Biol Eng Comput 1999; 37:704-9. [PMID: 10723876 DOI: 10.1007/bf02513371] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.
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Affiliation(s)
- V Schnabel
- Center for Sensory-Motor Interaction, Aalborg University, Denmark.
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23
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Bar-Ziv R, Tlusty T, Moses E, Safran SA, Bershadsky A. Pearling in cells: a clue to understanding cell shape. Proc Natl Acad Sci U S A 1999; 96:10140-5. [PMID: 10468576 PMCID: PMC17856 DOI: 10.1073/pnas.96.18.10140] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gradual disruption of the actin cytoskeleton induces a series of structural shape changes in cells leading to a transformation of cylindrical cell extensions into a periodic chain of "pearls." Quantitative measurements of the pearling instability give a square-root behavior for the wavelength as a function of drug concentration. We present a theory that explains these observations in terms of the interplay between rigidity of the submembranous actin shell and tension that is induced by boundary conditions set by adhesion points. The theory allows estimation of the rigidity and thickness of this supporting shell. The same theoretical considerations explain the shape of nonadherent edges in the general case of untreated cells.
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Affiliation(s)
- R Bar-Ziv
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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24
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Abstract
To account for the beading of myelinated fibers, and axons of unmyelinated nerve fibers as well of neurites of cultured dorsal root ganglia caused by mild stretching, a model is presented. In this model, membrane tension and hydrostatic pressure are the basic factors responsible for axonal constriction, which causes the movement of axonal fluid from the constricted regions into the adjoining axon, there giving rise to the beading expansions. Beading ranges from a mild undulation, with the smallest degree of stretch, to more globular expansions and narrow intervening constrictions as stretch is increased: the degree of constriction is physically limited by the compaction of the cytoskeleton within the axons. The model is a general one, encompassing the possibility that the membrane skeleton, composed mainly of spectrin and actin associated with the inner face of the axolemma, could be involved in bringing about the constrictions and beading.
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Affiliation(s)
- V S Markin
- Departments of Anesthesiology and Pain Management and Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9068, USA.
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25
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Ochs S, Pourmand R, Jersild RA, Friedman RN. The origin and nature of beading: a reversible transformation of the shape of nerve fibers. Prog Neurobiol 1997; 52:391-426. [PMID: 9304699 DOI: 10.1016/s0301-0082(97)00022-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nerve fibers which appear beaded (varicose, spindle-shaped, etc.) are often considered the result of pathology, or a preparation artifact. However, beading can be promptly elicited in fresh normal nerve by a mild stretch and revealed by fast-freezing and freeze-substitution, or by aldehyde fixating at a temperature near 0 degree C (cold-fixation). The key change in beading are the constrictions, wherein the axon is much reduced in diameter. Axoplasmic fluid and soluble components are shifted from the constrictions into the expansions leaving behind compacted microtubules and neurofilaments. Labeled cytoskeletal proteins carried down by slow axonal transport are seen to move with the soluble components and not to have been incorporated into and remain with, the cytoskeletal organelles on beading the fibers. Lipids and other components of the myelin sheath are also shifted from the constrictions into the expansions, with preservation of its fine structure and thickness. Additionally, myelin intrusions into the axons are produced and a localized bulging into the axon termed "leafing". The beading constrictions do not arise from the myelin sheath: beading occurs in the axons of unmyelinated fibers. It does not depend on the axonal cytoskeleton: exposure of nerves in vitro to beta, beta'-iminodipropionitrile (IDPN) disaggregates the cytoskeletal organelles and even augments beading. The hypothesis advanced was that the beading constrictions are due to the membrane skeleton; the subaxolemmal network comprised of spectrin/fodrin, actin, ankyrin, integrins and other transmembrane proteins. The mechanism can be activated directly by neurotoxins, metabolic changes, and by an interruption of axoplasmic transport producing Wallerian degeneration.
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Affiliation(s)
- S Ochs
- Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202, USA
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26
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Ochs S, Pourmand R, Jersild RA. Origin of beading constrictions at the axolemma: presence in unmyelinated axons and after beta,beta'-iminodipropionitrile degradation of the cytoskeleton. Neuroscience 1996; 70:1081-96. [PMID: 8848169 DOI: 10.1016/0306-4522(95)00390-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Myelinated nerve fibres become beaded when nerves are subjected to a mild stretch; the beading is seen as varicosities, a series of alternating constrictions and enlargements, when using freeze-substitution or cold-fixation to hold this labile form change in place during fixation. One possibility for how this form change comes about is that the myelin sheath or its Schwann cell initiates beading. We now report, however, that a similar beading is seen in the axons of unmyelinated fibres. In electron micrographs, longitudinal sections of axons show the series of constrictions and expansions typical of beading. In cross-sections, axons with unusually small diameter, corresponding to the constrictions, are seen to contain closely packed microtubules and neurofilaments while neighbouring swollen axons with widely dispersed microtubules correspond to the beading expansions. Another possibility for the form change is that the cytoskeleton is responsible for beading. We discovered that direct exposure of nerves to beta, beta'-iminodipropionitrile in vitro for 1-6 h causes both axonal microtubules and neurofilaments to become degraded and replaced by an amorphous residue. Nevertheless, beta,beta'-iminodipropionitrile-treated nerves show constrictions in myelinated fibres when stretched. An even greater degree of beading with narrower and longer constrictions appears in some fibres, with the expanded regions having oblate ends giving the appearance of a string of sausages. In cross-sections taken through the constrictions, a greater than usual reduction of axonal area was seen, this was due to the loss of cytoskeletal organelles which would act to limit the degree of constriction. With longer exposure to beta, beta'-iminodipropinitrile more fibres show complete degeneration of the cytoskeleton and form ovoids typical of Wallerian degeneration. Unmyelinated axons of beta, beta'-iminodipropionitrile-treated nerves which showed degeneration of their cytoskeleton with its replacement by amorphous material still demonstrated beading. As neither the myelin sheath nor the intact cytoskeleton within the axon is necessary for beading, by exclusion, we consider beading constrictions to be initiated at the level of the axolemma. In our hypothesis the membrane skeleton is responsible; namely, the spectrin, actin and other molecular species lining the inside of the axolemma and binding to transmembrane proteins. The membrane skeleton may be activated by stretch via transmembrane proteins (e.g. beta 1-integrins). The membrane skeleton mechanism may also be directly engaged in the production of Wallerian degeneration or be induced by neurotoxic agents.
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Affiliation(s)
- S Ochs
- Department of Physiology/Biophysics, Indiana University School of Medicine, Indianapolis 46202, USA
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