Journal articles on the topic 'Nerve mechanical analysis'
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1
Baer, Gerhard Alfred, and Ralph Beitzel. "Spinal cord injury: the cost of mechanical ventilation versus phrenic nerve stimulation." British Journal of Neuroscience Nursing 18, no. 3 (June 2, 2022): 134–36. http://dx.doi.org/10.12968/bjnn.2022.18.3.134.
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Patients with respiratory insufficiency caused by tetraplegia at or above the level of cervical segment two can be treated with phrenic nerve stimulation instead of mechanical ventilation. An analysis of the annual invoices for single use airway equipment of 20 patients using phrenic nerve stimulation and 20 patients who were mechanically ventilated was conducted. The initial implantation of the phrenic nerve stimulation device costs considerably more than the mechanical ventilation device. However, this analysis found that the cost of running a phrenic nerve stimulator device is lower because of the reduced amount of airway nursing equipment needed. This analysis demonstrates that the cost of implanting a phrenic nerve stimulator device would be repaid within 4 years.
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Lennertz, Richard C., Karen A. Medler, James L. Bain, Douglas E. Wright, and Cheryl L. Stucky. "Impaired sensory nerve function and axon morphology in mice with diabetic neuropathy." Journal of Neurophysiology 106, no. 2 (August 2011): 905–14. http://dx.doi.org/10.1152/jn.01123.2010.
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Diabetes is the most prevalent metabolic disorder in the United States, and between 50% and 70% of diabetic patients suffer from diabetes-induced neuropathy. Yet our current knowledge of the functional changes in sensory nerves and their distal terminals caused by diabetes is limited. Here, we set out to investigate the functional and morphological consequences of diabetes on specific subtypes of cutaneous sensory nerves in mice. Diabetes was induced in C57Bl/6 mice by a single intraperitoneal injection of streptozotocin. After 6–8 wk, mice were characterized for behavioral sensitivity to mechanical and heat stimuli followed by analysis of sensory function using teased nerve fiber recordings and histological assessment of nerve fiber morphology. Diabetes produced severe functional impairment of C-fibers and rapidly adapting Aβ-fibers, leading to behavioral hyposensitivity to both mechanical and heat stimuli. Electron microscopy images showed that diabetic nerves have axoplasm with more concentrated organelles and frequent axon-myelin separations compared with control nerves. These changes were restricted to the distal nerve segments nearing their innervation territory. Furthermore, the relative proportion of Aβ-fibers was reduced in diabetic skin-nerve preparations compared with nondiabetic control mice. These data identify significant deficits in sensory nerve terminal function that are associated with distal fiber loss, morphological damage, and behavioral hyposensitivity in diabetic C57Bl/6 mice. These findings suggest that diabetes damages sensory nerves, leading to functional deficits in sensory signaling that underlie the loss of tactile acuity and pain sensation associated with insensate diabetic neuropathy.
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Loizides, A., S. Peer, M. Plaikner, T. Djurdjevic, and H. Gruber. "Punched Nerve Syndrome: Ultrasonographic Appearance of Functional Vascular Nerve Impairment." Ultraschall in der Medizin - European Journal of Ultrasound 33, no. 04 (December 9, 2011): 352–56. http://dx.doi.org/10.1055/s-0031-1281831.
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Abstract Purpose: The mechanical impact of a neighboring vessel on a “punched” nerve segment is thought to be one possible cause of compression neuropathy but has not been proven definitively. We report on 9 subjects with unclear clinical mononeuropathies in whom we could clearly define peripheral nerve impairment by such vessels on real-time high-resolution ultrasound (HRUS). Materials and Methods: Nine subjects with unclear mononeuropathy based on clinical neurological examination were referred to our department for HRUS assessment. The shape, inner and outer echotexture, size and diameter, and overall integrity of these nerves were assessed including an exact analysis of the surrounding soft tissues to search for potentially extraneural pathology. This included duplex imaging to identify even tiny atypical vascular structures. Results: In all patients duplex HRUS showed the pulsatile and “punching” character of the relevant vessels and the direct mechanical impact of these vessel. The involved nerve segments appeared enlarged with a hypoechoic change of echotexture including at least partial masking of their inner fascicular texture. Conclusion: Although rare, a “punching” vessel can be the cause of a compression neuropathy. Therefore, duplex HRUS must be included in every HRUS examination of patients with otherwise unclear mononeuropathy.
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Akouissi, Outman, Stéphanie P. Lacour, Silvestro Micera, and Antonio DeSimone. "A finite element model of the mechanical interactions between peripheral nerves and intrafascicular implants." Journal of Neural Engineering 19, no. 4 (July 21, 2022): 046017. http://dx.doi.org/10.1088/1741-2552/ac7d0e.
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Abstract Objective. Intrafascicular peripheral nerve implants are key components in the development of bidirectional neuroprostheses such as touch-enabled bionic limbs for amputees. However, the durability of such interfaces is hindered by the immune response following the implantation. Among the causes linked to such reaction, the mechanical mismatch between host nerve and implant is thought to play a decisive role, especially in chronic settings. Approach. Here we focus on modeling mechanical stresses induced on the peripheral nerve by the implant’s micromotion using finite element analysis. Through multiple parametric sweeps, we analyze the role of the implant’s material, geometry (aspect-ratio and shape), and surface coating, deriving a set of parameters for the design of better-integrated implants. Main results. Our results indicate that peripheral nerve implants should be designed and manufactured with smooth edges, using materials at most three orders of magnitude stiffer than the nerve, and with innovative geometries to redistribute micromotion-associated loads to less delicate parts of the nerve such as the epineurium. Significance. Overall, our model is a useful tool for the peripheral nerve implant designer that is mindful of the importance of implant mechanics for long term applications.
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Michaelis, M., K. H. Blenk, W. Janig, and C. Vogel. "Development of spontaneous activity and mechanosensitivity in axotomized afferent nerve fibers during the first hours after nerve transection in rats." Journal of Neurophysiology 74, no. 3 (September 1, 1995): 1020–27. http://dx.doi.org/10.1152/jn.1995.74.3.1020.
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1. Spontaneous activity and ectopic mechanical excitability of axotomized unmyelinated and myelinated fibers in the sural nerve were examined in anesthetized rats. The analysis was performed within 30 h after the nerve lesion using single-fiber recordings that were performed proximal to the severed nerve end. 2. Among all unmyelinated fibers tested (n = 865), 4-8% exhibited persistent spontaneous activity of low and irregular frequency. The percentage of spontaneously active C fibers did not change significantly during the first 30 h. Only 6 of 796 A fibers had spontaneous activity. 3. Mechanical stimulation of the cut nerve end excited 5-8% of all C fibers under investigation. No development with time could be detected in the frequency of mechanically excitable C fibers. In contrast, beginning 6 h after nerve transection, the number of mechanically excitable A fibers rose with time, reaching 27% after 22-30 h. 4. Among the A fibers (C fibers) that exhibited mechanical excitability or spontaneous activity, only 4% (25%) had both properties, whereas 96% (75%) were either mechanosensitive or spontaneously active. 5. With time after the nerve lesion, the mean discharge rate of all spontaneously discharging C fibers decreased significantly from 49 imp/min (0.5-9 h after nerve lesion) to 11 imp/min after 22-30 h. The mean discharge rate of C fibers exhibiting solely spontaneous activity and those C fibers that were additionally mechanosensitive did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)
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Garg, Rohit, Safak Uygur, Joanna Cwykiel, and Maria Siemionow. "Development of Targeted Muscle Reinnervation Model in Hind Limb Amputated Rats." Journal of Reconstructive Microsurgery 34, no. 07 (April 1, 2018): 509–13. http://dx.doi.org/10.1055/s-0038-1639602.
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Background Targeted muscle reinnervation (TMR) is a novel approach to postamputation neuroma pain; however, this has not been explicitly studied. The purpose of this study was to develop a TMR model in hind limb amputated rats. Methods Ten hind limbs from 5 Sprague Dawley cadaver rats were used. Sciatic nerve, main branches of the sciatic nerve (common peroneal, tibial, sural), motor branches from the sciatic nerve to the biceps femoris and cauda femoris, gluteal nerve and its motor branches to the semimembranosus, and biceps femoris and femoral nerve were dissected to look for consistent nerve anatomy that can be used for TMR in the rat hind limb amputation model. Transfemoral amputation was performed and two types of coaptations were made: common peroneal nerve to motor branch to biceps femoris and tibial nerve to motor branch to semimembranosus. Results The total surgical time for the dissection, amputation, and coaptation of nerves was ∼90 minutes. A total of 100 nerves were dissected in 10 rat hind limbs. Anatomical dissections were straightforward to perform. Anatomy of the dissected nerves was consistent. Hind limb amputations were performed without damaging the target muscles and nerves. Nerve lengths were sufficient for coaptation without any tension. Conclusions To the best of our knowledge, this is the first report on TMR model in hind limb amputated rats. This model will allow for mechanical, electromyography (EMG), and histological analysis for future assessment of neuroma prevention.
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Sekiya, Tetsuji, Masahiro Matsumoto, Ken Kojima, Kazuya Ono, Yayoi S. Kikkawa, Shinpei Kada, Hideaki Ogita, et al. "Mechanical stress-induced reactive gliosis in the auditory nerve and cochlear nucleus." Journal of Neurosurgery 114, no. 2 (February 2011): 414–25. http://dx.doi.org/10.3171/2010.2.jns091817.
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Object Hearing levels following microsurgical treatment gradually deteriorate in a number of patients treated for vestibular schwannoma (VS), especially in the subacute postoperative stage. The cause of this late-onset deterioration of hearing is not completely understood. The aim of this study was to investigate the possibility that reactive gliosis is a contributory factor. Methods Mechanical damage to nerve tissue is a feature of complex surgical procedures. To explore this aspect of VS treatment, the authors compressed rat auditory nerves with 2 different degrees of injury while monitoring the compound action potentials of the auditory nerve and the auditory brainstem responses. In this experimental model, the axons of the auditory nerve were quantitatively and highly selectively damaged in the cerebellopontine angle without permanent compromise of the blood supply to the cochlea. The temporal bones were processed for immunohistochemical analysis at 1 week and at 8 weeks after compression. Results Reactive gliosis was induced not only in the auditory nerve but also in the cochlear nucleus following mechanical trauma in which the general shape of the auditory brainstem response was maintained. There was a substantial outgrowth of astrocytic processes from the transitional zone into the peripheral portion of the auditory nerve, leading to an invasion of dense gliotic tissue in the auditory nerve. The elongated astrocytic processes ran in parallel with the residual auditory neurons and entered much further into the cochlea. Confocal images disclosed fragments of neurons scattered in the gliotic tissue. In the cochlear nucleus, hypertrophic astrocytic processes were abundant around the soma of the neurons. The transverse diameter of the auditory nerve at and proximal to the compression site was considerably reduced, indicating atrophy, especially in rats in which the auditory nerve was profoundly compressed. Conclusions The authors found for the first time that mechanical stress to the auditory nerve causes substantial reactive gliosis in both the peripheral and central auditory pathways within 1–8 weeks. Progressive reactive gliosis following surgical stress may cause dysfunction in the auditory pathways and may be a primary cause of progressive hearing loss following microsurgical treatment for VS.
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DAI, PEISHAN, HAN HAN, YALI ZHAO, and MIN FAN. "FINITE ELEMENT ANALYSIS OF THE MECHANICAL CHARACTERISTICS OF GLAUCOMA." Journal of Mechanics in Medicine and Biology 16, no. 04 (June 2016): 1650060. http://dx.doi.org/10.1142/s0219519416500603.
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Purpose: Construct a finite element model of the human eye to quantitatively analyze the mechanical characteristics of the human eye, especially the glaucoma damage process of the optic nerve head (ONH). Method: First, the geometry model of the human eye with nonuniform thickness was established based on a reasonable hypothesis and assumptions. Because the ONH is an important factor for glaucoma, we refine the structure of the ONH with lamina cribrosa. Then, mesh division was applied for finite element analysis. To simplify the complexity of the analysis, the materials of the model were assumed to be isotropic linear elastic materials, and physical properties such as Young’s modulus and Poisson’s ratio were set according to published literature. Next, proper constraints and loads were applied to the model and solved with a finite element method. Result: A finite element model of the human eye was created to simulate the mechanical characteristics of the eye structures under high intraocular pressure (IOP). The ONH depressed 1.057[Formula: see text]mm under 0.009[Formula: see text]MPa pressure to simulate high IOP. Conclusion: The constructed model is able to quantitatively simulate excavation of the optic disc and damage of the optic nerve. The result proved Houcheng Liang’s hypothesis about the ONH damage mechanism in glaucoma.
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Winkelstein, Beth A., and Joyce A. DeLeo. "Mechanical Thresholds for Initiation and Persistence of Pain Following Nerve Root Injury: Mechanical and Chemical Contributions at Injury." Journal of Biomechanical Engineering 126, no. 2 (April 1, 2004): 258–63. http://dx.doi.org/10.1115/1.1695571.
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There is much evidence supporting the hypothesis that magnitude of nerve root mechanical injury affects the nature of the physiological responses which can contribute to pain in lumbar radiculopathy. Specifically, injury magnitude has been shown to modulate behavioral hypersensitivity responses in animal models of radiculopathy. However, no study has determined the mechanical deformation thresholds for initiation and maintenance of the behavioral sensitivity in these models. Therefore, it was the purpose of this study to quantify the effects of mechanical and chemical contributions at injury on behavioral outcomes and to determine mechanical thresholds for pain onset and persistence. Male Holtzman rats received either a silk or chromic gut ligation of the L5 nerve roots, a sham exposure of the nerve roots, or a chromic exposure in which no mechanical deformation was applied but chromic gut material was placed on the roots. Using image analysis, nerve root radial strains were estimated at the time of injury. Behavioral hypersensitivity was assessed by measuring mechanical allodynia continuously throughout the study. Chromic gut ligations produced allodynia responses for nerve root strains at two-thirds of the magnitudes of those strains which produced the corresponding behaviors for silk ligation. Thresholds for nerve root compression producing the onset (8.4%) and persistence of pain (17.4%–22.2%) were determined for silk ligation in this lumbar radiculopathy model. Such mechanical thresholds for behavioral sensitivity in a painful radiculopathy model begin to provide biomechanical data which may have utility in broader experimental and computational models for relating injury biomechanics and physiologic responses of pain.
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Hsiang, Shih-Wei, Chin-Chuan Tsai, Fuu-Jen Tsai, Tin-Yun Ho, Chun-Hsu Yao, and Yueh-Sheng Chen. "Novel use of biodegradable casein conduits for guided peripheral nerve regeneration." Journal of The Royal Society Interface 8, no. 64 (April 27, 2011): 1622–34. http://dx.doi.org/10.1098/rsif.2011.0009.
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Recent advances in nerve repair technology have focused on finding more biocompatible, non-toxic materials to imitate natural peripheral nerve components. In this study, casein protein cross-linked with naturally occurring genipin (genipin-cross-linked casein (GCC)) was used for the first time to make a biodegradable conduit for peripheral nerve repair. The GCC conduit was dark blue in appearance with a concentric and round lumen. Water uptake, contact angle and mechanical tests indicated that the conduit had a high stability in water and did not collapse and cramped with a sufficiently high level of mechanical properties. Cytotoxic testing and terminal deoxynucleotidyl transferase dUTP nick-end labelling assay showed that the GCC was non-toxic and non-apoptotic, which could maintain the survival and outgrowth of Schwann cells. Non-invasive real-time nuclear factor-κB bioluminescence imaging accompanied by histochemical assessment showed that the GCC was highly biocompatible after subcutaneous implantation in transgenic mice. Effectiveness of the GCC conduit as a guidance channel was examined as it was used to repair a 10 mm gap in the rat sciatic nerve. Electrophysiology, labelling of calcitonin gene-related peptide in the lumbar spinal cord, and histology analysis all showed a rapid morphological and functional recovery for the disrupted nerves. Therefore, we conclude that the GCC can offer great nerve regeneration characteristics and can be a promising material for the successful repair of peripheral nerve defects.
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Bartholomew, Ania, Tyler Slone, Michael Ciesa, Nicholas A. Cheney, and Brian C. Clark. "Analysis of Complications Following Distal Ankle Nerve Blocks for Foot and Ankle Procedures." Foot & Ankle Orthopaedics 7, no. 1 (January 2022): 2473011421S0010. http://dx.doi.org/10.1177/2473011421s00104.
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Category: Ankle; Arthroscopy; Bunion; Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: Popliteal nerve blocks are a common procedure employed by anesthesiologists to augment intraoperative anesthesia and provide postoperative pain control. Unfortunately, these can be associated with unintended complications including pain, numbness, and foot drop, sometimes without clear resolution. Studies from Kahn (2017), Anderson (2015), Park (2018), Lauf (2020) suggest complications higher than previously reported with Lauf (2020) finding short-term complication rates of 10.1% and 4.1% long-term as confirmed by EMG. Our study looked to address the complication rates from an alternative anesthetic procedure, a distal ankle nerve block involving anesthesia to the five nerve(s) more intimately involved in the surgical procedure. This alternative technique may provide equivalent anesthetic properties and pain relief as popliteal blocks, with fewer complications for many patients across various demographics. Methods: We retrospectively reviewed patient charts and messaging from 2019 to 2021 that received a distal ankle field block for various surgical procedures including ankle arthroscopy, ankle fractures, and lateral ankle stabilizations. The five nerves anesthetized in the distal ankle nerve block included the tibial, superficial and deep peroneal, sural, and saphenous. Thus far, 61 surgeries have been reviewed and analyzed for neuropathic complications and confirmed via EMG. Results: Of the 61 patients analyzed, 3 patients were found to have a superficial peroneal neuropathy that included dorsal numbness as a result of the distal ankle block, resulting in a 4.92% complication rate. 1 patient required a rescue block to be performed postoperatively for pain. The remaining 57 patients recovered appropriately and without complications. No motor complications have been found from patients receiving distal ankle nerve blocks, as performed by the senior author. Conclusion: With the absence of motor complications and markedly reduced incidence of sensory complications, distal ankle nerve blocks may be a beneficial alternative to popliteal nerve blocks for various foot and ankle orthopedic surgeries. As motor complications can result in life-altering disability, an anesthetic procedure with reduced negative motor outcomes can improve surgery and recovery prognosis. Future directions for this study include adding more patients to increase the sample size, as well as continuing to follow current patients, monitoring symptoms or complications.
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Nawrotek, Katarzyna, Monika Kubicka, Justyna Gatkowska, Marek Wieczorek, Sylwia Michlewska, Adrian Bekier, Radosław Wach, and Karolina Rudnicka. "Controlling the Spatiotemporal Release of Nerve Growth Factor by Chitosan/Polycaprolactone Conduits for Use in Peripheral Nerve Regeneration." International Journal of Molecular Sciences 23, no. 5 (March 5, 2022): 2852. http://dx.doi.org/10.3390/ijms23052852.
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Tubular polymeric structures have been recognized in the treatment of peripheral nerves as comparable to autologous grafting. The best therapeutic outcomes are obtained with conduits releasing therapeutic molecules. In this study, a new approach for the incorporation of biologically active agent-loaded microspheres into the structure of chitosan/polycaprolactone conduits was developed. The support of a polycaprolactone helix formed by 3D melt extrusion was coated with dopamine in order to adsorb nerve growth factor-loaded microspheres. The complex analysis of the influence of process factors on the coverage efficiency of polycaprolactone helix by nerve grow factor-loaded microspheres was analyzed. Thus, the PCL helix characterized with the highest adsorption of microspheres was subjected to nerve growth factor release studies, and finally incorporated into chitosan hydrogel deposit through the process of electrophoretic deposition. It was demonstrated by chemical and physical tests that the chitosan/polycaprolactone conduit meets the requirements imposed on peripheral nerve implants, particularly mimicking mechanical properties of surrounding soft tissue. Moreover, the conduit may support regrowing nerves for a prolonged period, as its structure and integrity persist upon incubation in lysozyme-contained PBS solution up to 28 days at body temperature. In vitro cytocompatibility toward mHippoE-18 embryonic hippocampal cells of the chitosan/polycaprolactone conduit was proven. Most importantly, the developed conduits stimulate axonal growth and support monocyte activation, the latter is advantageous especially at early stages of nerve regeneration. It was demonstrated that, through the described approach for controlling spatiotemporal release of nerve growth factors, these biocompatible structures adjusted to the specific peripheral nerve injury case can be manufactured.
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Romero-Sandoval, Alfonso, and James C. Eisenach. "Perineural Clonidine Reduces Mechanical Hypersensitivity and Cytokine Production in Established Nerve Injury." Anesthesiology 104, no. 2 (February 1, 2006): 351–55. http://dx.doi.org/10.1097/00000542-200602000-00022.
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Background Partial sciatic nerve ligation (PSNL) produces axonal damage, a local inflammatory response, and wallerian degeneration. Cytokines secreted near the site of nerve injury are thought to play important roles in development and maintenance of central sensitization and neuropathic pain. Injection of clonidine at the site and time of nerve injury slows the development of PSNL-induced hypersensitivity and reduces local cytokine expression by actions on alpha2 adrenoceptors. The current study tested whether clonidine would have a similar effect in established nerve injury. Methods Rats underwent unilateral PSNL, and perineural saline, clonidine, or BRL44408 plus clonidine was injected 2 weeks later. Three days after perineural injection, withdrawal threshold to mechanical stimulation of the hind paw ipsilateral and contralateral to PSNL was determined, and tissues were removed for cytokine analysis. Results PSNL was accompanied by a proinflammatory pattern of cytokine content in neural structures and hypersensitivity ipsilaterally with few changes contralaterally. Perineural clonidine, but not saline, partially reversed the hypersensitivity, accompanied by reduced concentrations of interleukin 6 and interleukin 1beta in the sciatic nerve. The effect of clonidine on hypersensitivity and these cytokines was blocked by the alpha2-adrenoceptor antagonist, BRL44408. Conclusions These data suggest that perineural clonidine acts on alpha2 adrenoceptors to reduce hypersensitivity in established nerve injury, likely by an immunomodulatory mechanism, and may be effective in patients in the weeks after nerve injury.
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Lee, Kangwook, Jin Mo Ku, Yu-Jeong Choi, Hyun Ha Hwang, Miso Jeong, Yun-Gyeong Kim, Min Jeong Kim, and Seong-Gyu Ko. "Herbal Prescription SH003 Alleviates Docetaxel-Induced Neuropathic Pain in C57BL/6 Mice." Evidence-Based Complementary and Alternative Medicine 2021 (August 10, 2021): 1–10. http://dx.doi.org/10.1155/2021/4120334.
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Docetaxel-based therapy has been applied to kill cancers including lung and breast cancers but frequently causes peripheral neuropathy such as mechanical allodynia. Lack of effective drugs for chemotherapy-induced peripheral neuropathy (CIPN) treatment leads us to find novel drugs. Here, we investigated whether and how novel anticancer herbal prescription SH003 alleviates mechanical allodynia in mouse model of docetaxel-induced neuropathic pain. Docetaxel-induced mechanical allodynia was evaluated using von Frey filaments. Nerve damage and degeneration in paw skin of mice were investigated by immunofluorescence staining. Neuroinflammation markers in bloodstream, lumbar (L4-L6) spinal cord, and sciatic nerves were examined by ELISA or western blot analysis. Docetaxel (15.277 mg/kg) was intravenously injected into the tail vein of C57BL/6 mice, and mechanical allodynia was followed up. SH003 (557.569 mg/kg) was orally administered at least 60 min before the mechanical allodynia test, and von Frey test was performed twice. Docetaxel injection induced mechanical allodynia, and SH003 administration restored withdrawal threshold. Meanwhile, degeneration of intraepidermal nerve fibers (IENF) was observed in docetaxel-treated mice, but SH003 treatment suppressed it. Moreover, docetaxel injection increased levels of TNF-α and IL-6 in plasma and expressions of phospho-NF-κB and phospho-STAT3 in both of lumbar spinal cord and sciatic nerves, while SH003 treatment inhibited those changes. Taken together, it is worth noting that TNF-α and IL-6 in plasma and phospho-NF-κB and phospho-STAT3 in spinal cord and sciatic nerves are putative biomarkers of docetaxel-induced peripheral neuropathy (DIPN) in mouse models. In addition, we suggest that SH003 would be beneficial for alleviation of docetaxel-induced neuropathic pain.
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Ramburrun, Poornima, Pradeep Kumar, Elias Ndobe, and Yahya E. Choonara. "Gellan-Xanthan Hydrogel Conduits with Intraluminal Electrospun Nanofibers as Physical, Chemical and Therapeutic Cues for Peripheral Nerve Repair." International Journal of Molecular Sciences 22, no. 21 (October 26, 2021): 11555. http://dx.doi.org/10.3390/ijms222111555.
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Optimal levels of functional recovery in peripheral nerve injuries remain elusive due to the architectural complexity of the neuronal environment. Commercial nerve repair conduits lack essential guidance cues for the regenerating axons. In this study, the regenerative potential of a biosimulated nerve repair system providing three types of regenerative cues was evaluated in a 10 mm sciatic nerve-gap model over 4 weeks. A thermo-ionically crosslinked gellan-xanthan hydrogel conduit loaded with electrospun PHBV-magnesium oleate-N-acetyl-cysteine (PHBV-MgOl-NAC) nanofibers was assessed for mechanical properties, nerve growth factor (NGF) release kinetics and PC12 viability. In vivo functional recovery was based on walking track analysis, gastrocnemius muscle mass and histological analysis. As an intraluminal filler, PHBV-MgOl-NAC nanofibers improved matrix resilience, deformation and fracture of the hydrogel conduit. NGF release was sustained over 4 weeks, governed by Fickian diffusion and Case-II relaxational release for the hollow conduit and the nanofiber-loaded conduit, respectively. The intraluminal fibers supported PC12 proliferation by 49% compared to the control, preserved up to 43% muscle mass and gradually improved functional recovery. The combined elements of physical guidance (nanofibrous scaffolding), chemical cues (N-acetyl-cysteine and magnesium oleate) and therapeutic cues (NGF and diclofenac sodium) offers a promising strategy for the regeneration of severed peripheral nerves.
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YAMAGUCHI, Takahiro, Hironori TAKEDA, Yoshitaka KAMEO, and Taiji ADACHI. "The mechanical analysis of parallel folding of cerebellum depending on oriented nerve fibers." Proceedings of the JSME Conference on Frontiers in Bioengineering 2022.32 (2022): 2B11. http://dx.doi.org/10.1299/jsmebiofro.2022.32.2b11.
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Heyters, Marc, Alain Carpentier, Jacques Duchateau, and Karl Hainaut. "Twitch Analysis as an Approach to Motor Unit Activation During Electrical Stimulation." Canadian Journal of Applied Physiology 19, no. 4 (December 1, 1994): 451–61. http://dx.doi.org/10.1139/h94-037.
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The mechanical twitch in response to increasing electrical stimulus intensity, delivered both over the motor point and motor nerve, was recorded in the first dorsal interosseous (FDI) and the adductor pollicis (AP), and only over the motor point in the soleus (Sol), lateral (LG), and medial (MG) gastrocnemius muscles of human subjects. The relationship between intensity of electrical stimulation (ES) and twitch torque showed a positive linear regression in all muscles. In the FDI and AP the relationship was not significantly different when ES was applied at the motor point or over the motor nerve. At small intensities of activation, ES induced larger twitch torques in the MG and LG, which contain a roughly equal proportion of slow and fast motor units (MUs) compared to the Sol, which is composed mainly of slow type fibres. Moreover, the relationship between ES intensity and twitch time-to-peak is best fitted in all muscles by a power curve that shows a greater twitch time-to-peak range in its initial part for muscles containing a larger proportion of fast MUs (LG, MG) than for muscles mainly composed of slow MUs (Sol). In conclusion, these results induced by ES at the motor point and/or over the motor nerve confirm the concept of a reversed sequence of MU activation, as compared to voluntary contractions, and document this viewpoint in muscles of different function and composition. The reversed sequence of MU activation is more clearly evident during motor point ES. Key words: muscle contraction, mechanical twitch, motor point, nerve
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Huang, Chih Ling, Ying Yi Lin, and Jiunn Der Liao. "Immobilization of Chitosan on the Plasma-Activated Poly-L-Lactic Acid Film Surface Using Evaporated Acrylic Acid as the Intermediate." Advances in Science and Technology 49 (October 2006): 197–202. http://dx.doi.org/10.4028/www.scientific.net/ast.49.197.
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Nerve bridging is to suture a biomaterial-made conduit and to overpass the damaged nerve end to end with microsurgery. Poly L-lactide (PLLA) is an excellent biomaterial that has biocompatible, biodegradable and good mechanical properties; it is thus potential to be engineered as nerve conduits and manufactured as scaffolds for nerve tissue replacement. On the other hand, chitosan provides cell affinity and considerably promotes nerves regeneration. This study is to apply plasma processing for PLLA film modification, graft the plasma-modified film with vaporized acrylic acid (AAc) monomers and then immobilize chitosan by amide bonding on the pAAc-grafted surface. This work using plasma-activation and subsequent evaporation of AAc greatly avoids PLLA thermal cracking and remaining the PLLA film in good mechanical properties. Surface morphologies are evaluated by Nano Focus. Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) are respectively employed for determining elements’ functionalities and chemical structures. Moreover, biological functionalities of the chitosan-immobilized PLLA films are thereafter assessed by antibacterial test and in vitro fibroblastic cell growth assay. The result exhibits that chitosan is immobilized on the modified PLLA films, which is plasma-activated subsequent to the evaporation of AAc. The process does not induce thermal cracking. In vitro fibroblastic cell growth assay on the chitosan-immobilized PLLA films has demonstrated that fibroblast cells on the surface become circular in shape. It decreases cell growth rate and the development of scar tissues, which may thereafter promote the effect of nerve repairing.
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Yin, Kaiyang, Prajan Divakar, Jennifer Hong, Karen L. Moodie, Joseph M. Rosen, Cathryn A. Sundback, Michael K. Matthew, and Ulrike G. K. Wegst. "Freeze-cast Porous Chitosan Conduit for Peripheral Nerve Repair." MRS Advances 3, no. 30 (2018): 1677–83. http://dx.doi.org/10.1557/adv.2018.194.
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ABSTRACTA novel freeze-cast porous chitosan conduit for peripheral nerve repair with highly-aligned, double layered porosity, which provides the ideal mechanical and chemical properties was designed, manufactured, and assessed in vivo. Efficacies of the conduit and the control inverted nerve autograft were evaluated in bridging 10-mm Lewis rat sciatic nerve gap at 12 weeks post-implantation. Biocompatibility and regenerative efficacy of the porous chitosan conduit were evaluated through the histomorphometric analysis of longitudinal and transverse sections. The porous chitosan conduit was found to have promising regenerative characteristics, promoting the desired neovascularization, and axonal ingrowth and alignment through a combination of structural, mechanical and chemical cues.
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Kumai, Tsukasa, Yoshinori Takakura, Kouichi Akiyama, Ichiro Higashiyama, and Susumu Tamai. "Histopathological Study of Nonosseous Tarsal Coalition." Foot & Ankle International 19, no. 8 (August 1998): 525–31. http://dx.doi.org/10.1177/107110079801900804.
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Histopathological analysis was performed on 55 feet in 48 patients with nonosseous tarsal coalitions. Histological findings were similar to those observed at the tendinous attachment site of Osgood-Schlatter disease, accessory navicular, and bipartite patellae. No nerve elements were observed in the fibrocartilaginous tissue at the coalition. Nerve elements were present only in periosteum and articular capsule surrounding the coalition. Pain in the tarsal coalition is not mediated by nerve elements at the coalition site itself. It is assumed that the pain is caused by mechanical abnormality that results from incomplete coalition. Incomplete coalition produces microfractures and re-modelings on the boundaries between bone and the coalition, which then lead to degenerative changes. This mechanical abnormality seems to induce pain via free nerve endings in the periosteum and in the articular capsule surrounding the coalition.
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Li, Yun Gong, and Jin Ping Zhang. "Comparison and Analysis of Two Auditory Models Faced to Mechanical Faults Diagnosis." Advanced Materials Research 430-432 (January 2012): 1081–86. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.1081.
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Auditory model is a signal analysis system with simulating the mechanism of the human auditory system, and it is not only suitable for speech signal but also vibration signal for mechanical faults diagnosis. In this paper, the work of analysis and comparison for EA and ZCPA auditory model is done. The reason and characteristics of simulation mode of auditory nerve in two auditory model is illustrated. By analyzing vibration signals of different rotor faults, the performances of distinguishing different faults and stability for one kind fault for two models are compared. The results show that ZCPA model is more flexible and stable.
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Jack, Megan M., and Douglas E. Wright. "204 Voluntary Exercise Modulates Macrophage Polarization Following Sciatic Nerve Injury and Improves Functional Recovery in Mice." Neurosurgery 64, CN_suppl_1 (August 24, 2017): 255. http://dx.doi.org/10.1093/neuros/nyx417.204.
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Abstract INTRODUCTION Peripheral nerve injury is associated with trauma and is often amenable to surgery. Functional recovery remains a challenging clinical problem that often leads to significant morbidity. Therapies that augment surgical repair may be beneficial in functional outcomes. Macrophages are responsible for the breakdown of debris following injury as well as promotion of regenerative signals. Macrophage polarization is the process by which macrophages take on phenotypically distinct functions based on the local environment and signaling cues. Exercise has been shown to drive macrophage polarization from a pro-inflammatory M1 phenotype towards an anti-inflammatory M2 phenotype in numerous tissues, but remains uninvestigated in the peripheral nervous system. METHODS The purpose of our study was to identify how exercise affects macrophage polarization, motor and sensory function, and neuroregeneration following sciatic nerve crush. Male and female C57BL/6 mice underwent sciatic nerve crush injury and were then given access to running wheels (exercised) or not given access to running wheels (sedentary) for 4 weeks. Analysis included behavioral assessments, anatomical studies, and in vitro studies. RESULTS >Exercised mice ran an average of 2.9 km per night. Injured exercised mice were protected from the development of thermal hyperalgesia. Exercised mice had fewer paw slips on beam walk testing compared to sedentary mice. No differences were measured in mechanical sensitivity or motor coordination and balance. Motor nerve conduction velocities from injured exercised animals were significantly higher than injured sedentary animals suggesting improved nerve recovery with exercise. Injured sciatic nerves from exercised mice demonstrated increased M2 macrophages compared to sciatic nerves from injured sedentary mice. The behavioral changes and altered macrophage polarization correlated with increased epidermal nerve fiber density, improved myelination, and increased in vitro neurite outgrowth from injured exercised animals. CONCLUSION Exercise alters macrophage polarization towards an anti-inflammatory phenotype which improves repair and recovery of the injured peripheral nerve.
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Matsui, Takashi, Keisuke Takahashi, Madoka Moriya, Shigenori Tanaka, Norio Kawahara, and Katsuro Tomita. "Quantitative Analysis of Edema in the Dorsal Nerve Roots Induced by Acute Mechanical Compression." Spine 23, no. 18 (September 1998): 1931–36. http://dx.doi.org/10.1097/00007632-199809150-00002.
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Huang, Wei, Zheng Cao, Ye Wu, Zhenzhou Li, Li Li, and Yantao Zhao. "Bone Marrow Mesenchymal Stem Cells (BMSCs) Promote Neuronal Cell Repair in Spinal Cord Injury by Regulating Toll-Like Receptor 4/Nuclear Factor-Kappa B Signaling Pathway." Journal of Biomaterials and Tissue Engineering 11, no. 10 (October 1, 2021): 2064–69. http://dx.doi.org/10.1166/jbt.2021.2791.
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SCI (SCI) poses a challenge to nerve cell repair strategies. SCI injury can lead to the development of inflammation, which in turn can exacerbate nerve cell damage. The TLR4/NF-kappa B signaling pathway is a common inflammatory signaling pathway. Since BMSCs are involved in injury repair, whether they can promote the repair of SCI neuronal cells have not been reported. Spinal cord nerve cells were cultured in vitro and divided into mechanical injury group and BMSCs group followed by analysis of cell proliferation activity and detection of altered apoptotic activity. Changes in the concentrations of IL-6 and IL-1β were measured by ELISA and cellular mitochondrial alterations was assessed by JG-B staining along with analysis of NF-kappa B, TLR4, related neurodevelopmental factor BDNF, and NGF expression by western blot. Mechanical damage to neuronal cells resulted in decreased cell proliferation, increased apoptotic activity, decreased cellular mitochondrial activity, increased TLR4 and NF-kappa B expression, decreased BDNF and NGF expression, as well as increased secertions of IL-6 and IL-1β (P < 0.05). In contrast, co-culture with BMSCs resulted in increased proliferation and decreased apoptosis of mechanically injured neuronal cells, increased cellular mitochondrial activity, with observation of the inverse changes in other factors (P < 0.05). In conclusion, BMSCs can suppress inflammation and promote repair of injured neuronal cells by inhibiting TLR4/NF-kappa B signaling.
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Liao, Chenlong, Min Yang, Pengfei Liu, Wenxiang Zhong, and Wenchuan Zhang. "Stable Rat Model of Mechanical Allodynia in Diabetic Peripheral Neuropathy: The Role of Nerve Compression." Journal of Reconstructive Microsurgery 34, no. 04 (February 2, 2018): 264–69. http://dx.doi.org/10.1055/s-0037-1621723.
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Background Preclinical studies involving animal models are essential for understanding the underlying mechanisms of diabetic neuropathic pain. Methods Rats were divided into four groups: two controls and two experimental. Diabetes mellitus was induced by streptozotocin (STZ) injection in two experimental groups. The first group involved one sham operation. The second group involved one latex tube encircling the sciatic nerve. The vehicle-injection rats were used as two corresponding control groups: sham operation and encircled nerves. By the third week, STZ-injected rats with encircled nerves were further divided into three subgroups: one involving continuing observation and the other two involving decompression (removal of the latex tube) at different time points (third week and fifth week). Weight and blood glucose were monitored, and behavioral analysis, including paw withdrawal threshold (PWT) and latency, was performed every week during the experimental period (7 weeks). Results Hyperglycemia was induced in all STZ-injected rats. A significant increase in weight was observed in the control groups when compared with the experimental groups. By the third week, more STZ-injected rats with encircled nerves developed mechanical allodynia than those without (P < 0.05), while no significant difference was noted (P > 0.05) on the incidence of thermal hyperalgesia. Mechanical allodynia, but not thermal hyperalgesia, could be ameliorated by the removal of the latex tube at an early stage (third week). Conclusion With the combined use of a latex tube and STZ injection, a stable rat model of painful diabetic peripheral neuropathy (DPN) manifesting both thermal hyperalgesia and mechanical allodynia has been established.
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Xu, Ting-Min, Hong-Yu Chu, Ming Li, Zuliyaer Talifu, Han Ke, Yun-Zhu Pan, Xin Xu, et al. "Establishment of FK506-Enriched PLGA Nanomaterial Neural Conduit Produced by Electrospinning for the Repair of Long-Distance Peripheral Nerve Injury." Journal of Nanomaterials 2022 (August 22, 2022): 1–13. http://dx.doi.org/10.1155/2022/3530620.
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Peripheral nerve injury (PNI) is a serious complication of trauma. Autologous nerve transplantation is the gold standard for the treatment of long-distance peripheral nerve defects, but is often limited by insufficient donor sites, postoperative pain, and paresthesia at the donor site. Peripheral nerve tissue engineering has led to the development of neural conduits to replace autologous nerve grafts. This study aimed to evaluate a new type of electrospun nanomaterial neural conduit, enriched with tacrolimus (FK506), which is an FDA-approved immunosuppressant, for the repair of long-distance peripheral nerve injuries. Poly (lactic-co-glycolic acid) (PLGA) nanofibrous films, with FK506, were prepared by electrostatic spinning and rolled into hollow cylindrical nerve vessels with an inner diameter of 1 mm and length of 15 mm. Material characterization, mechanical testing, degradation, drug release, cytotoxicity, cell proliferation, and migration assays were performed in vitro. Long-distance sciatic nerve injuries in rats were repaired in vivo using electrospun nerve conduit bridging, and nerve regeneration and muscle and motor function recovery were evaluated by gait analysis, electrophysiology, and neuromuscular histology. Compared to PLGA, the PLGA/FK506 nanomaterial neural conduit showed little change in morphology, mechanical properties, and chemical structure. In vitro, PLGA/FK506 showed lower cytotoxicity and better biocompatibility and effectively promoted the proliferation, adhesion, and migration of Schwann cells. In vivo, PLGA/FK506 had a better effect on sciatic nerve index, compound muscle action potential intensity and delay time, and nerve regeneration quality 12 weeks post-transplantation, effectively promoting long-distance defect sciatic nerve regeneration and functional recovery in rats. FK506-enriched PLGA nanomaterial neural conduits offer an effective method for repairing long-distance peripheral nerve injury and have potential clinical applications.
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Husain, Syeda Fabeha, Raymond W. M. Lam, Tao Hu, Michael W. F. Ng, Z. Q. G. Liau, Keiji Nagata, Sanjay Khanna, et al. "Locating the Site of Neuropathic Pain In Vivo Using MMP-12-Targeted Magnetic Nanoparticles." Pain Research and Management 2019 (March 6, 2019): 1–11. http://dx.doi.org/10.1155/2019/9394715.
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Neuropathic pain remains underrecognised and ineffectively treated in chronic pain sufferers. Consequently, their quality of life is considerably reduced, and substantial healthcare costs are incurred. The anatomical location of pain must be identified for definitive diagnosis, but current neuropsychological tools cannot do so. Matrix metalloproteinases (MMP) are thought to maintain peripheral neuroinflammation, and MMP-12 is elevated particularly in such pathological conditions. Magnetic resonance imaging (MRI) of the peripheral nervous system has made headway, owing to its high-contrast resolution and multiplanar features. We sought to improve MRI specificity of neural lesions, by constructing an MMP-12-targeted magnetic iron oxide nanoparticle (IONP). Its in vivo efficiency was evaluated in a rodent model of neuropathic pain, where the left lumbar 5 (L5) spinal nerve was tightly ligated. Spinal nerve ligation (SNL) successfully induced mechanical allodynia, and thermal hyperalgesia, in the left hind paw throughout the study duration. These neuropathy characteristics were absent in animals that underwent sham surgery. MMP-12 upregulation with concomitant macrophage infiltration, demyelination, and elastin fibre loss was observed at the site of ligation. This was not observed in spinal nerves contralateral and ipsilateral to the ligated spinal nerve or uninjured left L5 spinal nerves. The synthesised MMP-12-targeted magnetic IONP was stable and nontoxic in vitro. It was administered onto the left L5 spinal nerve by intrathecal injection, and decreased magnetic resonance (MR) signal was observed at the site of ligation. Histology analysis confirmed the presence of iron in ligated spinal nerves, whereas iron was not detected in uninjured left L5 spinal nerves. Therefore, MMP-12 is a potential biomarker of neuropathic pain. Its detection in vivo, using IONP-enhanced MRI, may be further developed as a tool for neuropathic pain diagnosis and management.
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Chiang, Chien-Yi, Meei-Ling Sheu, Fu-Chou Cheng, Chun-Jung Chen, Hong-Lin Su, Jason Sheehan, and Hung-Chuan Pan. "Comprehensive analysis of neurobehavior associated with histomorphological alterations in a chronic constrictive nerve injury model through use of the CatWalk XT system." Journal of Neurosurgery 120, no. 1 (January 2014): 250–62. http://dx.doi.org/10.3171/2013.9.jns13353.
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Object Neuropathic pain is debilitating, and when chronic, it significantly affects the patient physically, psychologically, and socially. The neurobehavior of animals used as a model for chronic constriction injury seems analogous to the neurobehavior of humans with neuropathic pain. However, no data depicting the severity of histomorphological alterations of the nervous system associated with graded changes in neurobehavior are available. To determine the severity of histomorphological alteration related to neurobehavior, the authors created a model of chronic constrictive injury of varying intensity in rats and used the CatWalk XT system to evaluate neurobehavior. Methods A total of 60 Sprague-Dawley rats, weighing 250–300 g each, were randomly assigned to 1 of 5 groups that would receive sham surgery or 1, 2, 3, or 4 ligatures of 3-0 chromic gut loosely ligated around the left sciatic nerve. Neurobehavior was assessed by CatWalk XT, thermal hyperalgesia, and mechanic allodynia before injury and periodically after injury. The nerve tissue from skin to dorsal spinal cord was obtained for histomorphological analysis 1 week after injury, and brain evoked potentials were analyzed 4 weeks after injury. Results. Significant differences in expression of nerve growth factor existed in skin, and the differences were associated with the intensity of nerve injury. After injury, expression of cluster of differentiation 68 and tumor necrosis factor–α was increased, and expression of S100 protein in the middle of the injured nerve was decreased. Increased expression of synaptophysin in the dorsal root ganglion and dorsal spinal cord correlated with the intensity of injury. The amplitude of sensory evoked potential increased with greater severity of nerve damage. Mechanical allodynia and thermal hyperalgesia did not differ significantly among treatment groups at various time points. CatWalk XT gait analysis indicated significant differences for print areas, maximum contact maximum intensity, stand phase, swing phase, single stance, and regular index, with sham and/or intragroup comparisons. Conclusions. Histomorphological and electrophysiological alterations were associated with severity of nerve damage. Subtle neurobehavioral differences were detected by the CatWalk XT system but not by mechanical allodynia or thermal hyperalgesia. Thus, the CatWalk XT system should be a useful tool for monitoring changes in neuropathic pain, especially subtle alterations.
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Hamasaki, Toru, and Masami Iwamoto. "Computational analysis of the relationship between mechanical state and mechanoreceptor responses during scanning of a textured surface." Advances in Mechanical Engineering 11, no. 11 (November 2019): 168781401988526. http://dx.doi.org/10.1177/1687814019885263.
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Skin deformation caused by contact with an object is transduced into nerve signals by tactile mechanoreceptors, allowing humans to perceive tactile information. Previous research has revealed that the mechanical state associated with finger skin deformation at mechanoreceptor locations in a finite element model is correlated with the experimentally measured responses of slowly adapting type I mechanoreceptors. However, these findings were obtained under static contact conditions. Therefore, in this study, we calculated the von Mises stress at slowly adapting type I and rapidly adapting type I mechanoreceptor locations during dynamic scanning of a textured surface using a finite element model of the human finger. We then estimated the hypothetical responses of the mechanoreceptors and compared the estimated results with the nerve firing of the receptors in previous neurophysiological experiments. These comparisons demonstrated that the temporal history of von Mises stress at mechanoreceptor locations was more strongly correlated with the “number of” impulses (R2 = 0.93 for slowly adapting type I and R2 = 0.90 for rapidly adapting type I) than the impulse “rate” (R2 = 0.58 for slowly adapting type I and R2 = 0.53 for rapidly adapting type I). Our findings suggest that the temporal history of von Mises stress can be used to roughly estimate the number of impulses of mechanoreceptors during scanning of a textured surface.
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Hardy, Adam R., Bailey M. Steinworth, and Melina E. Hale. "Touch sensation by pectoral fins of the catfish Pimelodus pictus." Proceedings of the Royal Society B: Biological Sciences 283, no. 1824 (February 10, 2016): 20152652. http://dx.doi.org/10.1098/rspb.2015.2652.
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Mechanosensation is fundamental to many tetrapod limb functions, yet it remains largely uninvestigated in the paired fins of fishes, limb homologues. Here we examine whether membranous fins may function as passive structures for touch sensation. We investigate the pectoral fins of the pictus catfish ( Pimelodus pictus ), a species that lives in close association with the benthic substrate and whose fins are positioned near its ventral margin. Kinematic analysis shows that the pectoral fins are held partially protracted during routine forward swimming and do not appear to generate propulsive force. Immunohistochemistry reveals that the fins are highly innervated, and we observe putative mechanoreceptors at nerve fibre endings. To test for the ability to sense mechanical perturbations, activity of fin ray nerve fibres was recorded in response to touch and bend stimulation. Both pressure and light surface brushing generated afferent nerve activity. Fin ray nerves also respond to bending of the rays. These data demonstrate for the first time that membranous fins can function as passive mechanosensors. We suggest that touch-sensitive fins may be widespread in fishes that maintain a close association with the bottom substrate.
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Kim, Yoon J., Kyoung S. Lee, Soo G. Joe, and June-Gone Kim. "Incidence and quantitative analysis of dissociated optic nerve fiber layer appearance: real loss of retinal nerve fiber layer?" European Journal of Ophthalmology 28, no. 3 (April 11, 2017): 317–23. http://dx.doi.org/10.5301/ejo.5001067.
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Purpose: To assess the association between appearance of dissociated optic nerve fiber layer (DONFL) after internal limiting membrane (ILM) peeling and changes in the macular nerve fiber layer (NFL) area by spectral-domain optical coherence tomography (SD-OCT). Methods: This study included 132 consecutive patients who had successfully undergone vitrectomy with ILM peeling for idiopathic epiretinal membrane or macular holes and had been followed up for ≥6 months. Two examiners evaluated macular 5-line raster horizontal SD-OCT images and categorized the patients on the basis of presence (group I) or absence (group II) of DONFL. The average macular NFL areas in both groups were measured using ImageJ at baseline and 1, 3, and 6 months after surgery. Results: Among the 132 eyes of 132 patients, DONFL was noted in 42 (31.8%), 104 (78.8%), 106 (80.3%), and 106 (80.3%) eyes at 1, 3, and 6 months and at the last visit (12.8 ± 6.5 months) after surgery. These layers appeared most commonly between 1 and 3 months after ILM peeling. There was no significant difference in average macular NFL area between groups I and II (3453.4 ± 125.3 and 3513.0 ± 100.2 pixels, respectively) at 6 months after surgery (p = 0.56). Conclusions: Appearance of DONFL increased between postoperative months 1 and 3. Moreover, there was no significant difference in average NFL in terms of DONFL. Thus, appearance of DONFL might represent macular NFL rearrangement and reorganization rather than true mechanical damage to the NFL after ILM peeling.
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Cinelli, Ilaria, Michel Destrade, Peter McHugh, Antonia Trotta, Michael Gilchrist, and Maeve Duffy. "Head-to-nerve analysis of electromechanical impairments of diffuse axonal injury." Biomechanics and Modeling in Mechanobiology 18, no. 2 (November 14, 2018): 361–74. http://dx.doi.org/10.1007/s10237-018-1086-8.
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Wang, Qun, Xiao Zhang, Xiaolan He, Shibin Du, Zhenhua Jiang, Peng Liu, Lu Qi, Chen Liang, Nan Gu, and Yan Lu. "Synaptic Dynamics of the Feed-forward Inhibitory Circuitry Gating Mechanical Allodynia in Mice." Anesthesiology 132, no. 5 (May 1, 2020): 1212–28. http://dx.doi.org/10.1097/aln.0000000000003194.
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Abstract Background The authors’ previous studies have found that spinal protein kinase C γ expressing neurons are involved in the feed-forward inhibitory circuit gating mechanical allodynia in the superficial dorsal horn. The authors hypothesize that nerve injury enhances the excitability of spinal protein kinase C γ expressing interneurons due to disinhibition of the feed-forward inhibitory circuit, and enables Aβ primary inputs to activate spinal protein kinase C γ expressing interneurons. Methods Prkcg-P2A-tdTomato mice were constructed using the clustered regularly interspaced short palindromic repeats and clustered regularly interspaced short palindromic repeats-associated nuclease 9 technology, and were used to analyze the electrophysiologic properties of spinal protein kinase C γ expressing neurons in both normal conditions and pathologic conditions induced by chronic constriction injury of the sciatic nerve. Patch-clamp whole cell recordings were used to identify the nature of the dynamic synaptic drive to protein kinase C γ expressing neurons. Results Aβ fiber stimulation evoked a biphasic synaptic response in 42% (31 of 73) of protein kinase C γ expressing neurons. The inhibitory components of the biphasic synaptic response were blocked by both strychnine and bicuculline in 57% (16 of 28) of neurons. Toll-like receptor 5 immunoreactive fibers made close contact with protein kinase C γ expressing neurons. After nerve injury, the percentage of neurons double-labeled for c-fos and Prkcg-P2A-tdTomato in animals walking on a rotarod was significantly higher than that in the nerve injury animals (4.1% vs. 9.9%, 22 of 539 vs. 54 of 548,P < 0.001). Aβ fiber stimulation evoked burst action potentials in 25.8% (8 of 31) of protein kinase C γ expressing neurons in control animals, while the proportion increased to 51.1% (23 of 45) in nerve injury animals (P = 0.027). Conclusions The Prkcg-P2A-tdTomato mice the authors constructed provide a useful tool for further analysis on how the spinal allodynia gate works. The current study indicated that nerve injury enhanced the excitability of spinal protein kinase C γ expressing interneurons due to disinhibition of the feed-forward inhibitory circuit, and enabled Aβ primary inputs to activate spinal protein kinase C γ expressing interneurons. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New
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Sui, Xiaohong, Zhaolong Han, Dai Zhou, and Qiushi Ren. "Mechanical Analysis and Fabrication of a Penetrating Silicon Microprobe as an Artificial Optic Nerve Visual Prosthesis." International Journal of Artificial Organs 35, no. 1 (January 2012): 34–44. http://dx.doi.org/10.5301/ijao.5000034.
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Lee, Sang Chul, Tai Gyoon Yoon, Yong-Il Yoo, Yung-Jue Bang, Hae-Yeong Kim, Doo-Il Jeoung, and Hyun Jeong Kim. "Analysis of spinal cord proteome in the rats with mechanical allodynia after the spinal nerve injury." Biotechnology Letters 25, no. 24 (December 2003): 2071–78. http://dx.doi.org/10.1023/b:bile.0000007068.97472.89.
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Hogan, Quinn, Damir Sapunar, Ksenija Modric-Jednacak, and J. Bruce McCallum. "Detection of Neuropathic Pain in a Rat Model of Peripheral Nerve Injury." Anesthesiology 101, no. 2 (August 1, 2004): 476–87. http://dx.doi.org/10.1097/00000542-200408000-00030.
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Background Behavioral criteria that confirm neuropathic pain in animal injury models are undefined. Therefore, the authors sought clinically relevant measures that distinguish pain behavior of rats with peripheral nerve injury from those with sham injury. Methods The authors examined mechanical and thermal sensory sensitivity, comparing responses at baseline to responses after spinal nerve ligation (SNL group), sham nerve injury (sham group), or skin incision alone (control group). Results Substantial variance was evident in all sensory tests at baseline. After surgery, tests using brush, cold, or heat stimulation showed minimal distinctions between surgical groups. Postsurgical thresholds for flexion withdrawal from mechanical stimulation with von Frey fibers were decreased bilaterally in SNL and sham groups. In contrast, the probability of a complex hyperalgesia-type response with prolonged elevation, shaking, or licking of the paw was selectively increased on the ipsilateral side in the SNL group. Nonetheless, the effect of SNL on behavior was inconsistent, regardless of the sensory test. The behavioral measure that best distinguishes between SNL and sham groups and thereby best identifies animals with successful SNL-induced neuropathic pain is increased ipsilateral postsurgical probability of a hyperalgesia-type response to noxious mechanical stimulation. Using receiver operating characteristics analysis, mechanical hyperalgesia identifies a local SNL effect in approximately 60% of animals when specificity is required to be 90% or higher. Conclusions Simple withdrawal from von Frey tactile stimulation, although frequently used, is not a valid measure of peripheral nerve injury pain in rats, whereas a complex hyperalgesic-type response is a specific neuropathy-induced behavior.
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Gao, Hongyang, Yang You, Guoping Zhang, Feng Zhao, Ziyi Sha, and Yong Shen. "The Use of Fiber-Reinforced Scaffolds Cocultured with Schwann Cells and Vascular Endothelial Cells to Repair Rabbit Sciatic Nerve Defect with Vascularization." BioMed Research International 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/362918.
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To explore the feasibility of biodegradable fiber-reinforced 3D scaffolds with satisfactory mechanical properties for the repair of long-distance sciatic nerve defect in rabbits and effects of vascularized graft in early stage on the recovery of neurological function, Schwann cells and vascular endothelial cells were cocultured in the fiber-reinforced 3D scaffolds. Experiment group which used prevascularized nerve complex for the repair of sciatic nerve defect and control group which only cultured with Schwann cells were set. The animals in both groups underwent electromyography to show the status of the neurological function recovery at 4, 8, and 16 weeks after the surgery. Sciatic nerve regeneration and myelination were observed under the light microscope and electron microscope. Myelin sheath thickness, axonal diameter, and number of myelinated nerve fiber were quantitatively analyzed using image analysis system. The recovery of foot ulcer, the velocity of nerve conduction, the number of regenerating nerve fiber, and the recovery of ultrastructure were increased in the experimental group than those in the control group. Prevascularized tissue engineered fiber-reinforced 3D scaffolds for the repair of sciatic nerve defects in rabbits can effectively promote the recovery of neurological function.
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Mayank Manojbhai Raval and Shweta Rameshbhai Rakholiya. "The effect of neural tension technique versus neural sliding technique on pain and functional disability in cervical radiculopathy: A comparative study." International Journal of Science and Research Archive 6, no. 1 (May 30, 2022): 078–87. http://dx.doi.org/10.30574/ijsra.2022.6.1.0108.
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Background: Neural mobilization techniques are widely used to evaluate, and improve the mechanical and neurophysiological integrity of peripheral nerves in clinical populations. This techniques includes combination of joint movements that promote either neural tensioning (through displacement of nerve endings in opposite directions), or sliding (through displacement of nerve endings in same direction). It is a movement-based therapy, applied manually or via exercise. The nerve is mobilized relative to adjacent structures, with the aim of reducing symptoms through mechanisms that may be mechanical or neurophysiologic. Aim and Objectives: To determine the better treatment option between neural tension technique and neural sliding technique on pain and functional disability in patients with cervical radiculopathy. Methods: Total 30 subjects had been participated in the study according to inclusion criteria, and then divided them into two groups (Group A and Group B). Outcome measure neck disability index, numerical pain rating scale and patient specific functional scale were taken before treatment. Group A was given neural tension technique and Group B was given neural sliding technique. After treatment outcome measure was taken. Statistical analysis was done by post outcome measures of both the techniques. Result: Subjects in the neural tension technique group showed more improvement than neural sliding technique group. Thus neural tension technique has more significant effect on reducing Edema, hypoxia and other associated symptoms. In this way, it shows the improvement in numerical pain rating scale, Neck disability index and patient specific functional scale. Conclusion: Based on the findings of the present study concludes that the neural tension technique is more effective than neural sliding technique in the reduction of pain and functional disability.
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Yang, Jian, Jingbo Zhao, Pengmin Chen, Toshiya Nakaguchi, David Grundy, and Hans Gregersen. "Interdependency between mechanical parameters and afferent nerve discharge in hypertrophic intestine of rats." American Journal of Physiology-Gastrointestinal and Liver Physiology 310, no. 6 (March 15, 2016): G376—G386. http://dx.doi.org/10.1152/ajpgi.00192.2015.
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Partial intestinal obstruction causes smooth muscle hypertrophy, enteric neuronal plasticity, motility disorders, and biomechanical remodeling. In this study we characterized the stimulus-response function of afferent fibers innervating the partially obstructed jejunum. A key question is whether changes in afferent firing arise from remodeled mechanical tissue properties or from adaptive afferent processes. Partial obstruction was created by placing a polyethylene ring for 2 wk in jejunum of seven rats. Sham obstruction was made in six rats and seven rats served as normal controls. Firing from mesenteric afferent nerve bundles was recorded during mechanical ramp, relaxation, and creep tests. Stress-strain, spike rate increase ratio (SRIR), and firing rate in single units were assessed for evaluation of interdependency of the mechanical stimulations, histomorphometry data, and afferent nerve discharge. Partial intestinal obstruction resulted in hypertrophy and jejunal stiffening proximal to the obstruction site. Low SRIR at low strains during fast distension and at high stresses during slow distension was found in the obstructed rats. Single unit analysis showed increased proportion of mechanosensitive units but absent high-threshold (HT) units during slow stimulation, decreased number of HT units during fast stimulation, and shift from HT sensitivity towards low threshold sensitivity in the obstructed jejunum. Biomechanical remodeling and altered afferent response to mechanical stimulations were found in the obstructed jejunum. Afferents from obstructed jejunum preserved their function in encoding ongoing mechanical stimulation but showed changes in their responsiveness. The findings support that mechanical factors rather than adaption are important for afferent remodeling.
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Shepherd, Andrew J., Aaron D. Mickle, Judith P. Golden, Madison R. Mack, Carmen M. Halabi, Annette D. de Kloet, Vijay K. Samineni, et al. "Macrophage angiotensin II type 2 receptor triggers neuropathic pain." Proceedings of the National Academy of Sciences 115, no. 34 (August 6, 2018): E8057—E8066. http://dx.doi.org/10.1073/pnas.1721815115.
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Peripheral nerve damage initiates a complex series of structural and cellular processes that culminate in chronic neuropathic pain. The recent success of a type 2 angiotensin II (Ang II) receptor (AT2R) antagonist in a phase II clinical trial for the treatment of postherpetic neuralgia suggests angiotensin signaling is involved in neuropathic pain. However, transcriptome analysis indicates a lack of AT2R gene (Agtr2) expression in human and rodent sensory ganglia, raising questions regarding the tissue/cell target underlying the analgesic effect of AT2R antagonism. We show that selective antagonism of AT2R attenuates neuropathic but not inflammatory mechanical and cold pain hypersensitivity behaviors in mice. Agtr2-expressing macrophages (MΦs) constitute the predominant immune cells that infiltrate the site of nerve injury. Interestingly, neuropathic mechanical and cold pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs and AT2R-null hematopoietic cell transplantation. Our study identifies AT2R on peripheral MΦs as a critical trigger for pain sensitization at the site of nerve injury, and therefore proposes a translatable peripheral mechanism underlying chronic neuropathic pain.
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Cañadas, Pilar, Yrbani Lantigua, Amalia Enríquez-de-Salamanca, Itziar Fernandez, Salvador Pastor-Idoate, Eva M. Sobas, Antonio Dueñas-Laita, José Luis Pérez-Castrillón, Jose C. Pastor Jimeno, and Margarita Calonge. "Ocular Surface Pathology in Patients Suffering from Mercury Intoxication." Diagnostics 11, no. 8 (July 23, 2021): 1326. http://dx.doi.org/10.3390/diagnostics11081326.
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Purpose: To report the ocular surface pathology of patients suffering from acute/subacute mercury vapor intoxication. Design: Cross-sectional study. Participants: Male workers intoxicated with inorganic mercury referred for ophthalmic involvement and healthy control subjects. Methods: The following tests were performed: dry eye (DE)-related symptoms indicated by the ocular surface disease (OSDI) index questionnaire; tear osmolarity; analysis of 23 tear cytokine concentrations and principal component and hierarchical agglomerative cluster analyses; tear break-up time (T-BUT); corneal fluorescein and conjunctival lissamine green staining; tear production by Schirmer and tear lysozyme tests; mechanical and thermal corneal sensitivity (non-contact esthesiometry); and corneal nerve analysis and dendritic cell density by in vivo confocal microscopy (IVCM). Results: Twenty-two out of 29 evaluated patients entered the study. Most had DE-related symptoms (OSDI values > 12), that were severe in 63.6% of them. Tear osmolarity was elevated (>308 mOsms/L) in 83.4% of patients (mean 336.23 (28.71) mOsm/L). Corneal and conjunctival staining were unremarkable. T-BUT was low (<7 s) in 22.7% of patients. Schirmer test and tear lysozyme concentration were low in 13.6% and 27.3% of cases, respectively. Corneal esthesiometry showed patient mechanical (mean 147.81 (53.36) mL/min) and thermal thresholds to heat (+2.35 (+1.10) °C) and cold (−2.57 (−1.24) °C) to be significantly higher than controls. Corneal IVCM revealed lower values for nerve density (6.4 (2.94) n/mm2), nerve branching density (2 (2.50) n/mm2), and dendritic cell density (9.1 (8.84) n/mm2) in patients. Tear levels of IL-12p70, IL-6, RANTES, and VEGF were increased, whereas EGF and IP-10/CXCL10 were decreased compared to controls. Based on cytokine levels, two clusters of patients were identified. Compared to Cluster 1, Cluster 2 patients had significantly increased tear levels of 18 cytokines, decreased tear lysozyme, lower nerve branching density, fewer dendritic cells, and higher urine mercury levels. Conclusions: Patients suffering from systemic mercury intoxication showed symptoms and signs of ocular surface pathology, mainly by targeting the trigeminal nerve, as shown by alterations in corneal sensitivity and sub-basal nerve morphology.
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Bourquin, Anne-Frédérique, Maria Süveges, Marie Pertin, Nicolas Gilliard, Sylvain Sardy, Anthony C. Davison, Donat R. Spahn, and Isabelle Decosterd. "Assessment and analysis of mechanical allodynia-like behavior induced by spared nerve injury (SNI) in the mouse." Pain 122, no. 1 (May 2006): 14e1–14e14. http://dx.doi.org/10.1016/j.pain.2005.10.036.
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Chernov, Andrei V., Swathi K. Hullugundi, Kelly A. Eddinger, Jennifer Dolkas, Albert G. Remacle, Mila Angert, Brian P. James, Tony L. Yaksh, Alex Y. Strongin, and Veronica I. Shubayev. "A myelin basic protein fragment induces sexually dimorphic transcriptome signatures of neuropathic pain in mice." Journal of Biological Chemistry 295, no. 31 (June 12, 2020): 10807–21. http://dx.doi.org/10.1074/jbc.ra120.013696.
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In the peripheral nerve, mechanosensitive axons are insulated by myelin, a multilamellar membrane formed by Schwann cells. Here, we offer first evidence that a myelin degradation product induces mechanical hypersensitivity and global transcriptomics changes in a sex-specific manner. Focusing on downstream signaling events of the functionally active 84-104 myelin basic protein (MBP(84-104)) fragment released after nerve injury, we demonstrate that exposing the sciatic nerve to MBP(84-104) via endoneurial injection produces robust mechanical hypersensitivity in female, but not in male, mice. RNA-seq and systems biology analysis revealed a striking sexual dimorphism in molecular signatures of the dorsal root ganglia (DRG) and spinal cord response, not observed at the nerve injection site. Mechanistically, intra-sciatic MBP(84-104) induced phospholipase C (PLC)-driven (females) and phosphoinositide 3-kinase-driven (males) phospholipid metabolism (tier 1). PLC/inositol trisphosphate receptor (IP3R) and estrogen receptor co-regulation in spinal cord yielded Ca2+-dependent nociceptive signaling induction in females that was suppressed in males (tier 2). IP3R inactivation by intrathecal xestospongin C attenuated the female-specific hypersensitivity induced by MBP(84-104). According to sustained sensitization in tiers 1 and 2, T cell–related signaling spreads to the DRG and spinal cord in females, but remains localized to the sciatic nerve in males (tier 3). These results are consistent with our previous finding that MBP(84-104)–induced pain is T cell–dependent. In summary, an autoantigenic peptide endogenously released in nerve injury triggers multisite, sex-specific transcriptome changes, leading to neuropathic pain only in female mice. MBP(84-104) acts through sustained co-activation of metabolic, estrogen receptor–mediated nociceptive, and autoimmune signaling programs.
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Osthues, Tabea, Béla Zimmer, Vittoria Rimola, Kevin Klann, Karin Schilling, Praveen Mathoor, Carlo Angioni, et al. "The Lipid Receptor G2A (GPR132) Mediates Macrophage Migration in Nerve Injury-Induced Neuropathic Pain." Cells 9, no. 7 (July 21, 2020): 1740. http://dx.doi.org/10.3390/cells9071740.
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Nerve injury-induced neuropathic pain is difficult to treat and mechanistically characterized by strong neuroimmune interactions, involving signaling lipids that act via specific G-protein coupled receptors. Here, we investigated the role of the signaling lipid receptor G2A (GPR132) in nerve injury-induced neuropathic pain using the robust spared nerve injury (SNI) mouse model. We found that the concentrations of the G2A agonist 9-HODE (9-Hydroxyoctadecadienoic acid) are strongly increased at the site of nerve injury during neuropathic pain. Moreover, G2A-deficient mice show a strong reduction of mechanical hypersensitivity after nerve injury. This phenotype is accompanied by a massive reduction of invading macrophages and neutrophils in G2A-deficient mice and a strongly reduced release of the proalgesic mediators TNFα, IL-6 and VEGF at the site of injury. Using a global proteome analysis to identify the underlying signaling pathways, we found that G2A activation in macrophages initiates MyD88-PI3K-AKT signaling and transient MMP9 release to trigger cytoskeleton remodeling and migration. We conclude that G2A-deficiency reduces inflammatory responses by decreasing the number of immune cells and the release of proinflammatory cytokines and growth factors at the site of nerve injury. Inhibiting the G2A receptor after nerve injury may reduce immune cell-mediated peripheral sensitization and may thus ameliorate neuropathic pain.
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Goyal, Arsh, Saumendra Kumar Bajpai, and Ramakrishnan Swaminathan. "Analysis on the effect of eye globe diameters on the biomechanics of posterior ocular tissues during horizontal adduction." Current Directions in Biomedical Engineering 8, no. 2 (August 1, 2022): 536–39. http://dx.doi.org/10.1515/cdbme-2022-1137.
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Abstract In this work, an attempt has been made to analyze the influence of pathological changes in eye globe dimensions towards the mechanical responses of optic nerve head tissues during eye adductions. For this study, a 3D baseline model geometry of posterior ocular tissues has been constructed. The eye globe diameters of the model are modified to mimic the changes in ocular globe morphology in control, glaucoma, myopia and glaucoma with myopia conditions. Adductions are simulated for each modified model as the rotation of the globe from 1o to 10o in steps of 1o. von Mises strain in lamina cribrosa (LC) and posterior displacement of LC are estimated. Results show that strains developed in LC and its posterior displacement are higher in diseased eyes compared to healthy eyes. It appears that eyes with higher axial length and globe anisotropy are more susceptible to optic nerve head damage. This study might be extended to assess the progression of glaucomatous optic neuropathy.
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Pitera, Tomasz, Grzegorz Guzik, Piotr Biega, Marta Tarczyńska, and Krzysztof Gawęda. "Analysis of Difficulties and Complications Following Implantation of Modular Prostheses in Patients with Lower Limb Bone Tumours." Ortopedia Traumatologia Rehabilitacja 22, no. 4 (August 31, 2020): 243–52. http://dx.doi.org/10.5604/01.3001.0014.3460.
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Background. The implantation of a modular prosthesis is the most popular method of reconstruction of bone defects in oncological patients. Along with clear-cut benefits associated with this procedure, there is also an increased risk of complications. Common complications include deep infections, aseptic loosening and mechanical implant damage. This study assessed the risk of complications following the implantation of a resection prosthesis in patients with lower limb bone tumours and to evaluate difficulties encountered during the treatment. Material and methods. A total of 149 patients with lower limb tumours treated at the Department of Oncological Orthopaedics in Brzozów had resection prostheses implanted in the years 2016 and 2017. We analysed this series and available literature reports with regard to complications of the procedure and those encountered during the treatment. Results. The mean duration of the surgical procedure was 117±45 minutes. Intraoperative complications occurred in 18 cases. Gluteal muscle failure was seen in 34 (43%) of the 74 patients with proximal femoral tumours, and impaired knee extension was noted in 4 (67%) of the 6 patients following resection of the proximal tibia. There were two cases of dislocation following megaprosthetic reconstruction of the hip joint. Impaired wound healing was noted in 7 (5%) patients. Post-operative trophic lesions of the skin were seen in 2 (2%), and peripheral nerve damage in 2 (2%) patients (fibular nerve). Thromboembolic complications were noted in 3 (3%) patients. No aseptic complications, mechanical implant damage or deaths were recorded. Conclusions. 1. The most frequently encountered complication following the implantation of a modular prosthesis was muscle failure, which was associated with the extent of the procedure. 2. Aseptic loosening and mechanical implant damage were rare and occurred in the early postoperative period.
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Sinkjaer, T., J. Nielsen, and E. Toft. "Mechanical and electromyographic analysis of reciprocal inhibition at the human ankle joint." Journal of Neurophysiology 74, no. 2 (August 1, 1995): 849–55. http://dx.doi.org/10.1152/jn.1995.74.2.849.
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1. The purpose of the present study is to investigate how reciprocal inhibition influences the mechanical and electromyographic (EMG) properties of the ankle plantar flexors in humans during a voluntary contraction. 2. At different levels of maintained plantar flexion contractions ranging from 0 to 20 Nm, the size of the soleus EMG stretch reflex and the ankle joint stiffness (ration between the torque increment and the amplitude of the stretch) were measured in response to an imposed dorsiflexion. At matched plantar flexion contraction levels, stretch responses were compared before and after reversible block of the common peroneal nerve (CPN). Stretch responses were also measured during an attempted voluntary fictive dorsiflexion after CPN block. 3. In the preactivated soleus muscles, the phasic EMG response to stretch consisted of two peaks labeled M1 and M2. After CPN block, the M1 short-latency stretch reflex on average increased by 25 +/- 5.7%, mean +/- SD (P < 0.001), and the M2 stretch reflex increased on average by 29 +/- 13.0% (P = 0.002). 4. The total stiffness of the ankle joint during a stretch is the sum of the nonreflex and the reflex mediated stiffness. The total stiffness after CPN block increased on average by 13 +/- 2.7% (P = 0.002) and the estimated reflex stiffness by 33 +/- 6.5% (P < 0.001). 5. When the subjects were asked to make a strong dorsiflexion after CPN block, the soleus stretch reflex was depressed to the extent that the reflex mediated mechanical effect around the ankle joint was abolished.(ABSTRACT TRUNCATED AT 250 WORDS)
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Potapov, O. O., O. P. Kmyta, and O. O. Tsyndrenko. "MODERN ASPECTS OF THE USE OF NERVE CONDUCTORS IN PERIPHERAL NERVOUS SYSTEM INJURY." Eastern Ukrainian Medical Journal 8, no. 2 (2020): 137–44. http://dx.doi.org/10.21272/eumj.2020;8(2):137-144.
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Peripheral nerve injuries account for 4 % of all injuries, and the consequences of trauma are a major medical and social problem, since they are characterized by a significant and long-term decline in limb function, and a high level of disability in patients. According to our data, up to 40% of patients sought specialized care for more than 6 months after the injury, and 19.9% were treated conservatively for an unreasonably long period of time. It led to an increase in the portion of unsatisfactory treatment results, since the prognosis of the further functional and useful degree of nerve recovery worsens with increasing time after injury. The main objective was to select the optimal option of biocompatible material for implementation in practice in case of traumatic peripheral nerve damage. Materials and methods. The analysis of medical literature for 2015–2020 was conducted. First of all, it should be noted that modern non-biological resorbable tubes are made of polyglycolic and polylactic acids. Non-resorbable tubes, including silicone, have shown undesirable effects, including axon compression during regeneration and the reaction of a fibrous foreign body. Hollow cylindrical tubes can be manufactured in several ways, such as electrospinning, crosslinking, physical film rolling, injection molding, melt extrusion, and braiding. Adequate surgical treatment of peripheral nerve injuries requires that the surgeon, in addition to an accurate knowledge of the anatomical details of the affected area, would also be familiar with microsurgical methods and had necessary equipment to operate. The main procedure in peripheral nerve surgery is the restoration of nerve continuity, which can be obtained by direct coaptation between the two ends of a severed nerve or by the introduction of nerve grafts to replace a defect in nerve tissue. Polyester is the most common synthetic material used in neural tissue engineering, along with polylactic acid, polycaprolactone, and polyglycolic acid. In combination with mesenchymal stem cells of the bone marrow, polylactic acid showed better results and accelerated the recovery of peripheral nerves. Polylactic acid directed the migration of Schwann's cells and induced the formation of a normal nervous structure. It was proved that the polycaprolactone material had an effect similar to that of autografts in nerve repair, and its characteristics were better than in a polylactic acid tube. Polyglycolic acid also possesses sufficient mechanical properties and can be used to repair a nerve defect. Artificial synthetic materials have good biocompatibility and biodegradability with minimal toxicity. For the production of high-purity polymer monomers, which are necessary for the manufacture of the frame, much time and financial costs are required. Moreover, the elasticity and hardness of such materials are imperfect. Three main natural biomaterials are used in tissue repair: collagen, silk, and gelatin. Collagen tube is the most widely used biological material in clinical practice. Silk materials with the protein fibroin, which promote the release of certain substrates, such as nerve growth factor particles, and provide more nutrients and a more favorable microenvironment for nerve repair, are worth noticing. Silk fibroin has good compatibility with the neurons of the dorsal root ganglia and supports cell growth. Gelatin materials are preferred due to the reduction of micromanipulation during nerve recovery. Natural biomaterials are easy to obtain in sufficient quantities; they have good biocompatibility and biodegradability and are easily absorbed by the body. However, each natural biomaterial has its drawbacks. Some of them are brittle or break down in a humid environment. Some natural materials are insoluble in water and traditional organic solvents, which limits their use. One of the most widely used biopolymers of natural origin is chitosan. Chitosan, derived by chitin deacetylation, plays a supporting, protective, and guiding role in the early stage of recovery of peripheral nerves and can provide a relatively stable, localized microenvironment during regeneration. Chitosan is absorbed and gradually decomposed in the late phase of recovery and regeneration of the nervous system. Issues regarding graphene-based nanomaterials use are considered. Graphene is a two-dimensional carbon nanomaterial with good optical, electrical and mechanical properties. It should be noted that when graphene nanoparticles incorporate into a chitosan or gelatin frame and are used to repair peripheral nerve damage in rats, this has contributed to the regeneration of the damaged nerve more quickly. Graphene also reduced the inflammatory response and accelerated the migration of endogenous neuroblasts. Hence, the use of these materials is not well understood due to the significant duration of recovery of the denervated proximal end of the nerve, so further research is needed to identify the advantages or disadvantages of their use.
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Fairbanks, Carolyn A., H. Oanh Nguyen, Brent M. Grocholski, and George L. Wilcox. "Moxonidine, a Selective Imidazoline–α2-Adrenergic Receptor Agonist, Produces Spinal Synergistic Antihyperalgesia with Morphine in Nerve-injured Mice." Anesthesiology 93, no. 3 (September 1, 2000): 765–73. http://dx.doi.org/10.1097/00000542-200009000-00026.
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Background Moxonidine, a novel imidazoline-alpha2-adrenergic receptor-selective analgesic, was recently identified as antinociceptive but has yet to be evaluated in neuropathic pain models. alpha2-adrenergic receptor-selective analgesics, and high-efficacy opioids, effectively inhibit neuropathic pain behaviors in rodents. In contrast, morphine potency and efficacy decreases in states of neuropathic pain, both in rodents and in humans, but may be restored or enhanced by coadministration of morphine with alpha2-adrenergic receptor-selective analgesics. The current experiments extend the evaluation of opioid-coadjuvant interactions in neuropathic subjects by testing the respective antihyperalgesic interactions of moxonidine and clonidine with morphine in a test of mechanical hyperalgesia. Methods Nerve-injured mice (Chung model) were spinally administered moxonidine, clonidine, morphine, and the combinations moxonidine-morphine and clonidine-morphine. Hyperalgesia was detected by von Frey monofilament stimulation (3.3 mN) to the hind paws (plantar surface). The ED50 values were calculated and the interactions tested by isobolographic analysis. Results In nerve-injured mice, moxonidine, clonidine, and morphine all dose-dependently inhibited mechanical hyperalgesia. Furthermore, the combinations of moxonidine-morphine and clonidine-morphine resulted in substantial leftward shifts in the dose-response curves compared with those of each agonist administered separately. The calculated ED50 values of the dose-response curves of these combinations were significantly lower than their corresponding theoretical additive ED50 values. These results confirmed that both interactions were synergistic. Conclusions Moxonidine and clonidine both synergize with morphine to inhibit paw withdrawal from nociceptive mechanical stimuli in nerve-injured mice.
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Guo, Yi Chen, Yu Xuan Wang, Yan Ping Ge, Lu Jia Yu, and Jun Guo. "Analysis of subcellular structural tension in axonal growth of neurons." Reviews in the Neurosciences 29, no. 2 (February 23, 2018): 125–37. http://dx.doi.org/10.1515/revneuro-2017-0047.
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AbstractThe growth and regeneration of axons are the core processes of nervous system development and functional recovery. They are also related to certain physiological and pathological conditions. For decades, it has been the consensus that a new axon is formed by adding new material at the growth cone. However, using the existing technology, we have studied the structural tension of the nerve cell, which led us to hypothesize that some subcellular structural tensions contribute synergistically to axonal growth and regeneration. In this review, we classified the subcellular structural tension, osmotic pressure, microfilament and microtubule-dependent tension involved controllably in promoting axonal growth. A squeezing model was built to analyze the mechanical mechanism underlying axonal elongation, which may provide a new view of axonal growth and inspire further research.