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Pyun SY, Kang MR, Lee JY, Kuk KJ, Oh SI, Bae JS. Early discrimination of sensorimotor Guillain-Barré syndrome into demyelinating or axonal subtype by automated nerve excitability testing. J Peripher Nerv Syst 2017; 22:85-91. [DOI: 10.1111/jns.12208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 01/25/2023]
Affiliation(s)
- So Young Pyun
- Department of Neurology; National Police Hospital; Seoul Korea
| | - Mi-Ri Kang
- Department of Neurology; Busan Paik Hospital, Inje University College of Medicine; Busan Korea
| | - Ju Young Lee
- Department of Neurology, Kangdong Sacred Heart Hospital; Hallym University College of Medicine; Seoul Korea
| | - Kim Jong Kuk
- Department of Neurology; Dong-A University College of Medicine; Busan Korea
| | - Seong-Il Oh
- Department of Neurology; Busan Paik Hospital, Inje University College of Medicine; Busan Korea
| | - Jong Seok Bae
- Department of Neurology, Kangdong Sacred Heart Hospital; Hallym University College of Medicine; Seoul Korea
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Coggan JS, Bittner S, Stiefel KM, Meuth SG, Prescott SA. Physiological Dynamics in Demyelinating Diseases: Unraveling Complex Relationships through Computer Modeling. Int J Mol Sci 2015; 16:21215-36. [PMID: 26370960 PMCID: PMC4613250 DOI: 10.3390/ijms160921215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/21/2015] [Accepted: 08/25/2015] [Indexed: 11/16/2022] Open
Abstract
Despite intense research, few treatments are available for most neurological disorders. Demyelinating diseases are no exception. This is perhaps not surprising considering the multifactorial nature of these diseases, which involve complex interactions between immune system cells, glia and neurons. In the case of multiple sclerosis, for example, there is no unanimity among researchers about the cause or even which system or cell type could be ground zero. This situation precludes the development and strategic application of mechanism-based therapies. We will discuss how computational modeling applied to questions at different biological levels can help link together disparate observations and decipher complex mechanisms whose solutions are not amenable to simple reductionism. By making testable predictions and revealing critical gaps in existing knowledge, such models can help direct research and will provide a rigorous framework in which to integrate new data as they are collected. Nowadays, there is no shortage of data; the challenge is to make sense of it all. In that respect, computational modeling is an invaluable tool that could, ultimately, transform how we understand, diagnose, and treat demyelinating diseases.
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Affiliation(s)
- Jay S Coggan
- NeuroLinx Research Institute, La Jolla, CA 92039, USA.
| | - Stefan Bittner
- Department of Neurology, Institute of Physiology, Universitätsklinikum Münster, 48149 Münster, Germany.
| | | | - Sven G Meuth
- Department of Neurology, Institute of Physiology, Universitätsklinikum Münster, 48149 Münster, Germany.
| | - Steven A Prescott
- Neurosciences and Mental Health, the Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
- Department of Physiology and the Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5G 1X8, Canada.
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Stephanova DI, Daskalova M. Electrotonic potentials in simulated chronic inflammatory demyelinating polyneuropathy at 20°C-42°C. J Integr Neurosci 2015; 14:235-52. [PMID: 25916252 DOI: 10.1142/s0219635215500119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Threshold electrotonus changes have been studied following warming to 37°C and cooling to 25°C in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). To extend the tracking of these changes also during hypothermia (≤ 25°C) and hyperthermia (≥ 40°C), and to explain their mechanisms, we investigate the effects of temperature (from 20°C to 42°C) on polarizing nodal and internodal electrotonic potentials and their current kinetics in previously simulated case of 70% CIDP. The computations use our temperature-dependent multi-layered model of the myelinated human motor nerve fiber. While the changes of electrotonic potentials and their current kinetics are largely similar for the physiological range of 28-37°C, they are altered during hypothermia and hyperthermia in the normal and CIDP cases. The normal (at 37°C) resting membrane potential is further depolarized or hyperpolarized during hypothermia or hyperthermia, respectively, and the internodal current types defining these changes are the same for both cases. Unexpectedly, our results show that in the CIDP case, the lowest and highest critical temperatures for blocking of electrotonic potentials are 20°C and 39°C, while in the normal case the highest critical temperature for blocking of these potentials is 42°C. In the temperature range of 20-39°C, the relevant potentials in the CIDP case, except for the lesser value (at 39°C) in hyperpolarized resting membrane potential, are modified: (i) polarizing nodal and depolarizing internodal electrotonic potentials and their defining currents are increased in magnitude; (ii) inward rectifier (I IR ) and leakage (I Lk ) currents, defining the hyperpolarizing internodal electrotonic potential, are gradually increased with the rise of temperature from 20°C to 39°C, and (iii) the accommodation to long-lasting hyperpolarization is greater than to depolarization. The present results suggest that the electrotonic potentials in patients with CIDP are in high risk for blocking not only during hypothermia and hyperthermia, but they are also in risk for worsening at the temperature range of 37-39°C.
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Affiliation(s)
- D I Stephanova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad., G. Bontchev Str., Bl. 21, Sofia 1113, Bulgaria
| | - M Daskalova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad., G. Bontchev Str., Bl. 21, Sofia 1113, Bulgaria
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Stephanova DI, Daskalova M, Mladenov M. Conducting processes in simulated chronic inflammatory demyelinating polyneuropathy at 20°C-42°C. J Integr Neurosci 2015; 14:19-30. [PMID: 25597276 DOI: 10.1142/s0219635215500065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Decreased conducting processes leading usually to conduction block and increased weakness of limbs during cold (cold paresis) or warmth (heat paresis) have been reported in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). To explore the mechanisms of these symptoms, the effects of temperature (from 20°C to 42°C) on nodal action potentials and their current kinetics in previously simulated case of 70% CIDP are investigated, using our temperature dependent multi-layered model of the myelinated human motor nerve fiber. The results show that potential amplitudes have a bifid form at 20°C. As in the normal case, for the CIDP case, the nodal action potentials are determined mainly by the nodal sodium currents (I Na ) for the temperature range of 20-39°C, as the contribution of nodal fast and slow potassium currents (I Kf and I Ks ) to the total ionic current (Ii) is negligible. Also, the contribution of I Kf and I Ks to the membrane repolarization is enhanced at temperatures higher than 39°C. However, in the temperature range of 20-42°C, all potential parameters in the CIDP case, except for the conduction block during hyperthermia (≥ 40°C) which is again at 45°C, worsen: (i) conduction velocities and potential amplitudes are decreased; (ii) afterpotentials and threshold stimulus currents for the potential generation are increased; (iii) the current kinetics of action potentials is slowed and (iv) the conduction block during hypothermia (≤ 25°C) is at temperatures lower than 20°C. These potential parameters are more altered during hyperthermia and are most altered during hypothermia. The present results suggest that the conducting processes in patients with CIDP are in higher risk during hypothermia than hyperthermia.
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Affiliation(s)
- D I Stephanova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., Bl. 21, Sofia 1113, Bulgaria
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Stephanova DI, Krustev SM, Negrev N, Daskalova M. The myelin sheath aqueous layers improve the membrane properties of simulated chronic demyelinating neuropathies. J Integr Neurosci 2011; 10:105-20. [PMID: 21425485 DOI: 10.1142/s0219635211002646] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/21/2011] [Indexed: 11/18/2022] Open
Abstract
Recently, patients with chronic demyelinating neuropathies have demonstrated significant abnormalities in their multiple nerve excitability properties measured by a non-invasive threshold tracking technique. In order to expand our studies on the possible mechanisms underlying these abnormalities, which are not yet well understood, we investigate the contributions of the aqueous layers within the myelin sheath on multiple membrane properties of simulated fibre demyelinations. Four degrees of systematic paranodal demyelinations (two mild demyelinations termed PSD1 and PSD2, without/with aqueous layers respectively, and two severe demyelinations termed PSD3 and PSD4, with/without aqueous layers, respectively) are simulated using our previous multi-layered model of human motor nerve fibre. We studied the following parameters of myelinated axonal function: potentials (intracellular action, electrotonic-reflecting the propagating and accommodative fibre processes, respectively) and strength-duration time constants, rheobases, recovery cycles (reflecting the adaptive fibre processes). The results show that each excitability parameter is markedly potentiated when the aqueous layers within their paranodally demyelinated sheaths are taken into account. The effect of the aqueous layers is significantly higher on the propagating processes than on the accommodative and adaptive processes in the fibres. The aqueous layers restore the action potential propagation, which is initially blocked when they are not taken into account. The study provides new and important information on the mechanisms of chronic demyelinating neuropathies, such as chronic inflammatory demyelinating polyneuropathy (CIDP).
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Affiliation(s)
- D I Stephanova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. Bl. 21, Sofia 1113, Bulgaria.
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STEPHANOVA DI, KRUSTEV SM, DASKALOVA M. THE AQUEOUS LAYERS WITHIN THE MYELIN SHEATH MODULATE THE MEMBRANE PROPERTIES OF SIMULATED HEREDITARY DEMYELINATING NEUROPATHIES. J Integr Neurosci 2011; 10:89-103. [DOI: 10.1142/s0219635211002634] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 12/14/2010] [Indexed: 11/18/2022] Open
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Stephanova DI, Daskalova MS. Differences between the channels, currents and mechanisms of conduction slowing/block and accommodative processes in simulated cases of focal demyelinating neuropathies. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2008; 37:829-42. [PMID: 18286274 DOI: 10.1007/s00249-008-0284-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 01/21/2008] [Accepted: 01/31/2008] [Indexed: 10/22/2022]
Abstract
To clarify the differences between the mechanisms of conduction slowing/block and accommodative processes in focal demyelinating neuropathies, this computational study presents the kinetics of the ionic, transaxonal and transmyelin currents defining the intracellular and electrotonic potentials in different segments of human motor nerve fibres. The computations use our previous double cable model of the fibres. The simulated fibres have focal demyelination of internodes, paranodes or both together. The intracellular potentials are defined mainly by the Na+ current, as the contribution of the K+ fast and K+ slow currents to the total nodal ionic current is negligible. The paranodal demyelinations cause an increase in the transaxonal current and a decrease in the transmyelin current at the paranodal segments. However, there is an inverse relationship between the transaxonal and transmyelin currents at the same segments in the cases of internodal demyelination. The internodal ionic channels beneath the myelin sheath do not contribute to the intracellular potentials, but they show a high sensitivity to long-lasting pulses. The slow components of the electrotonic potentials depend on the activation of the channel types in the nodal or internodal axolemma, whereas the fast components of the potentials are determined mainly by the passive cable responses. However, the current kinetics changes (defining the investigated electrotonic changes) are relatively weak. The study summarizes the results from these modelling investigations on the mechanisms underlying the conduction slowing/block and accommodative processes in focal demyelinating neuropathies such as Guillain-Barré syndrome and multifocal motor neuropathy.
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Affiliation(s)
- Diana I Stephanova
- Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., Bl. 21, Sofia, 1113, Bulgaria.
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Stephanova D, Daskalova M. Membrane property abnormalities in simulated cases of mild systematic and severe focal demyelinating neuropathies. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:183-95. [PMID: 17786424 DOI: 10.1007/s00249-007-0215-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 07/27/2007] [Accepted: 08/03/2007] [Indexed: 10/22/2022]
Abstract
The investigation of multiple nerve membrane properties by mathematical models has become a new tool to study peripheral neuropathies. In demyelinating neuropathies, the membrane properties such as potentials (intracellular, extracellular, electrotonic) and indices of axonal excitability (strength-duration time constants, rheobases and recovery cycles) can now be measured at the peripheral nerves. This study provides numerical simulations of the membrane properties of human motor nerve fibre in cases of internodal, paranodal and simultaneously of paranodal internodal demyelinations, each of them mild systematic or severe focal. The computations use our previous multi-layered model of the fibre. The results show that the abnormally greater increase of the hyperpolarizing electrotonus, shorter strength-duration time constants and greater axonal superexcitability in the recovery cycles are the characteristic features of the mildly systematically demyelinated cases. The small decrease of the polarizing electrotonic responses in the demyelinated zone in turn leads to a compensatory small increase of these responses outside the demyelinated zone of all severely focally demyelinated cases. The paper summarizes the insights gained from these modeling studies on the membrane property abnormalities underlying the variation in clinical symptoms of demyelination in Charcot-Marie-Tooth disease type 1A, chronic inflammatory demyelinating polyneuropathy, Guillain-Barré syndrome and multifocal motor neuropathy. The model used provides an objective study of the mechanisms of these diseases which up till now have not been sufficiently well understood, because quite different assumptions have been given in the literature for the interpretation of the membrane property abnormalities obtained in hereditary, chronic and acquired demyelinating neuropathies.
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Affiliation(s)
- Diana Stephanova
- Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., Bl. 21, Sofia, 1113, Bulgaria.
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