The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Silvestro Micera - One of the best experts on this subject based on the ideXlab platform.
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a computational model for the stimulation of Rat Sciatic Nerve using a transverse intrafascicular multichannel electrode
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2011Co-Authors: Stanisa Raspopovic, Marco Capogrosso, Silvestro MiceraAbstract:Neuroprostheses based on electrical stimulation could potentially help disabled persons. They are based on neural interface that aim at creating an intimate contact with neural cells. The efficacy of neuroprostheses can be improved by increasing the selectivity of the neural interfaces used to stimulate specific subsets of cells. Selectivity is strongly influenced by interface design. Computer models can be useful for exploring the high dimensional space of design parameters with the aim to provide guidelines for the development of more efficient electrodes, with minimal animal use and optimization of manufacturing processes. The purpose of this study was to implement a realistic model of the performance of a transverse intrafascicular multichannel electrode (TIME) implanted into the Rat Sciatic Nerve. A realistic finite element method (FEM) model was developed taking into account the anatomical and physiological features of the Rat Sciatic Nerve. Electric potentials were calculated and interpolated voltages were applied to the model of a Rat Sciatic Nerve axon, based on experimental biophysical data. Results indicate that high intrafascicular and inter-fascicular selectivity values with low current levels can be achieved with TIMEs. The selectivity of TIMEs was also compared to an extraneural electrode, showing that higher selectivity with less current can be obtained. Using this model, the robustness of electrode performances for translational and rotational displacements were evaluated.
Xavier Navarro - One of the best experts on this subject based on the ideXlab platform.
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Biocompatibility of Chronically Implanted Transverse Intrafascicular Multichannel Electrode (TIME) in the Rat Sciatic Nerve
IEEE Transactions on Biomedical Engineering, 2011Co-Authors: Jordi Badia, Tim Boretius, Arán Pascual-font, Esther Udina, Thomas Stieglitz, Xavier NavarroAbstract:The transverse intrafascicular multichannel electrode (TIME) is intended to be transversally implanted in the peripheral Nerve and to selectively interface subsets of axons in different fascicles within the same Nerve. Two versions of TIME (TIME-2 and TIME-3) were designed and tested for biocompatibility and safety in the Sciatic Nerve of the Rat. TIME-2 was implanted in two groups: the first group had only an acute implant and the second group had chronic implantation for two months; a third group was also chronically implanted with the TIME-3 version, designed to avoid the mechanical traction produced by muscles motion. We evaluated the functional and morphological effects of either TIME-2 or TIME-3 implanted in the Rat Sciatic Nerve for two months. The results of the study indicate that implantation of the TIME-2 and TIME-3 devices in the Nerve did not cause significant axonal loss or demyelination, as evidenced by the functional and histological results. The results of this study indicate that the TIME-2 and TIME-3 designs are biocompatible and safe after chronic implantation in a small peripheral Nerve, such as the Rat Sciatic Nerve.
Robert R. Myers - One of the best experts on this subject based on the ideXlab platform.
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Effects of levobupivacaine and ropivacaine on Rat Sciatic Nerve blood flow
British journal of anaesthesia, 2005Co-Authors: Hervé Bouaziz, G. Iohom, Jean-pierre Estebe, W.m. Campana, Robert R. MyersAbstract:Background Ischaemia is one of the causative mechanisms of peripheral Nerve injury, a documented complication of regional anaesthesia. Local anaesthetics per se and/or vasopressor adjuvants may account for changes in peripheral Nerve blood flow. The aim of this study was to test the effects of levobupivacaine and ropivacaine in a Rat Sciatic Nerve model with respect to local blood flow and histopathological changes. Methods Forty-eight female Sprague–Dawley Rats were anaesthetized for left Sciatic Nerve exposure. After baseline Nerve blood flow measurement with a laser Doppler flowmeter, 0.2 ml of one of the following solutions was applied topically to the Nerve in a random fashion: saline 0.9%; lidocaine 10 mg ml −1 ; levobupivacaine 2.5 mg ml −1 ; levobupivacaine 5 mg ml −1 ; levobupivacaine 7.5 mg ml −1 ; ropivacaine 2 mg ml −1 ; ropivacaine 7.5 mg ml −1 ; and ropivacaine 7.5 mg ml −1 plus epinephrine 5 µg ml −1 ; all in saline 0.9%. Nerve blood flow was evaluated at 5-min intervals up to 30 min after local application of anaesthetic solution. Three animals per group were killed for histological evaluation 48 h later. Multiple one-way analyses of variance followed by Scheffe's post hoc test was used for statistical analysis. P Results Local anaesthetics at all concentRations tested caused significant reduction in Nerve blood flow. The combination of ropivacaine 7.5 mg ml −1 plus epinephrine did not reduce Nerve blood flow to a greater extent than ropivacaine 7.5 mg ml −1 alone. Low concentRations of levobupivacaine (2.5 and 5 mg ml −1 ) reduced Nerve blood flow to the same extent as lidocaine 10 mg ml −1 . No significant histological changes were observed at 48 h. Conclusion Despite acute reductions in peripheral Nerve blood flow, significant histopathological changes were not observed in this Rat Sciatic Nerve model after topical application of levobupivacaine and ropivacaine at concentRations relevant to clinical practice.
Stanisa Raspopovic - One of the best experts on this subject based on the ideXlab platform.
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a computational model for the stimulation of Rat Sciatic Nerve using a transverse intrafascicular multichannel electrode
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2011Co-Authors: Stanisa Raspopovic, Marco Capogrosso, Silvestro MiceraAbstract:Neuroprostheses based on electrical stimulation could potentially help disabled persons. They are based on neural interface that aim at creating an intimate contact with neural cells. The efficacy of neuroprostheses can be improved by increasing the selectivity of the neural interfaces used to stimulate specific subsets of cells. Selectivity is strongly influenced by interface design. Computer models can be useful for exploring the high dimensional space of design parameters with the aim to provide guidelines for the development of more efficient electrodes, with minimal animal use and optimization of manufacturing processes. The purpose of this study was to implement a realistic model of the performance of a transverse intrafascicular multichannel electrode (TIME) implanted into the Rat Sciatic Nerve. A realistic finite element method (FEM) model was developed taking into account the anatomical and physiological features of the Rat Sciatic Nerve. Electric potentials were calculated and interpolated voltages were applied to the model of a Rat Sciatic Nerve axon, based on experimental biophysical data. Results indicate that high intrafascicular and inter-fascicular selectivity values with low current levels can be achieved with TIMEs. The selectivity of TIMEs was also compared to an extraneural electrode, showing that higher selectivity with less current can be obtained. Using this model, the robustness of electrode performances for translational and rotational displacements were evaluated.
D Gambi - One of the best experts on this subject based on the ideXlab platform.
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Effect of rhTNF-alpha injection into Rat Sciatic Nerve.
Journal of neuroimmunology, 1999Co-Authors: A Uncini, A Di Muzio, G Di Guglielmo, M V De Angelis, G De Luca, A Lugaresi, D GambiAbstract:To assess whether TNF-alpha causes inflammatory demyelination or axonal degeneRation, we injected into Rat Sciatic Nerve saline, 100 U and 1000 U of rhTNF-alpha and studied the electrophysiological and pathological effects. At day 1 electrophysiology showed a slight reduction of proximal compound muscle action potential amplitude and pathology showed edema, inflammatory infiltRation of vessel walls and endoneurium only in Nerves injected with 1000 U of rhTNF-alpha. At day 5, there was no demyelination and a percentage of degeneRated fibers similar in the three groups. To study the blood-Nerve barrier, fluorescein isothiocyanate-labelled albumin was given intravenously after intraneural injection. The Nerves injected with 1000 U rhTNF-alpha showed a leakage of the tracer in the endoneurium. TNF-alpha does not appear, at the doses used, to have myelinotoxic or axonopathic properties. The electrophysiological effect at day 1 may be due to mechanical compression of Nerve fibers as a result of the blood-Nerve barrier damage with consequent endoneurial edema.
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Effect of rhTNF-α injection into Rat Sciatic Nerve
Journal of Neuroimmunology, 1999Co-Authors: A Uncini, A Di Muzio, G Di Guglielmo, M V De Angelis, G De Luca, A Lugaresi, D GambiAbstract:Abstract To assess whether TNF-α causes inflammatory demyelination or axonal degeneRation, we injected into Rat Sciatic Nerve saline, 100 U and 1000 U of rhTNF-α and studied the electrophysiological and pathological effects. At day 1 electrophysiology showed a slight reduction of proximal compound muscle action potential amplitude and pathology showed edema, inflammatory infiltRation of vessel walls and endoneurium only in Nerves injected with 1000 U of rhTNF-α. At day 5, there was no demyelination and a percentage of degeneRated fibers similar in the three groups. To study the blood–Nerve barrier, fluorescein isothiocyanate-labelled albumin was given intravenously after intraneural injection. The Nerves injected with 1000 U rhTNF-α showed a leakage of the tracer in the endoneurium. TNF-α does not appear, at the doses used, to have myelinotoxic or axonopathic properties. The electrophysiological effect at day 1 may be due to mechanical compression of Nerve fibers as a result of the blood–Nerve barrier damage with consequent endoneurial edema.
