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Neurotoxicology
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Sean D. McCann, Trevonne M. Thompson
Toxic peripheral neuropathies have been associated with a number of agents including suramin (used in the treatment of African sleeping sickness) and tacrolimus. N2O can cause a toxic peripheral neuropathy in addition to the subacute combined degeneration of the spinal cord described previously. Most toxic neuropathy syndromes are bilateral, due to axonopathies, and are potentially reversible. Present in some glues, n-hexane is metabolized to 2,5-hexanedione, which can crosslink neurofilaments and impair axonal transport resulting in axonopathy. Acrylamide (used primarily in polymer manufacturing) and vincristine can both interfere with axonal transport resulting in axonopathy. Nucleoside reverse transcriptase inhibitors used in the treatment of HIV can interfere with mitochondrial DNA synthesis, thereby causing peripheral neuropathy. Rarely, neuronopathy, as opposed to axonopathy, can be present, resulting in the irreversible death of the peripheral nerve cell body. This has been reported with doxorubicin injection into peripheral nerves and with pyridoxine overdose. Neuronopathy and axonopathy can be phenotypically identical at presentation. Treatment involves discontinuation of exposure to the offending agent.
Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
An important subset of living cells is excitable cells, which, when stimulated by an adequate stimulus of appropriate strength, undergo specific changes in the ionic permeabilities of their cell membranes. These permeability changes cause variations in the voltage across the cell membranes of excitable cells, which can result in a characteristic electric signal known as the action potential (AP) or nerve impulse (Chapter 3). The most important excitable animal cells are: (i) sensory cells, or receptors, which respond directly to environmental stimuli such as light, touch, taste, and smell, (ii) nerve cells, or neurons, whose primary function is the processing and transmission of information, and (iii) muscle cells, whose primary function is the development of a mechanical force of contraction. Neurons are discussed in Chapter 7, muscle cells and their receptors in Chapter 9.
Neurology
Published in Roy Palmer, Diana Wetherill, Medicine for Lawyers, 2020
The message transmitted by the axon is essentially electrical, created by chemical change; the message passes from axon to nerve cell body by chemical transmitters which may excite, depress, or modulate the activity of the recipient cell. Most drugs which influence neural activity work through either altering the transmitter activities or through influencing the excitivity of the cell membrane.
Blocking SP/NK1R signaling improves spinal cord hemisection by inhibiting the release of pro-inflammatory cytokines in rabbits
Published in The Journal of Spinal Cord Medicine, 2023
Yuehuan Zheng, Nannan Wang, Zhe Chen, Liqiang Shi, Xiangyang Xu
The BBB motor function assessment (Table 3) and Tarlov scoring system (Table 4) was used to assess the function recovery of rabbits. Compared with the SH group (n = 5), the BBB motor score and Tarlov score was notably lower in the OB group (n = 5) (all P < 0.05). Seven days after the SCI model was constructed, the spinal cord was taken for related experiments. The morphological structure of nerve cells in the SH group (n = 3) was intact and the cells in each layer were neatly arranged. Conversely, the nerve cells in the OB group (n = 3) were swollen and damaged (Fig. 1(A)). Compared with the SH group (n = 3), the nissl bodies (Fig. 1(A)), inflammatory cells (Fig. 1(A)), and mitochondrial edema (Fig. 1(B)) increased notably in the spinal cord of rabbits in the OB group (n = 3). In addition, SP increased substantially in OB group (n = 3) compared with SH group (n = 3). These results indicate that the rabbit SCI model was successfully established.
Reviving matrix for nerve reconstruction in rat model of acute and chronic complete spinal cord injury
Published in Neurological Research, 2022
Shimon Rochkind, Mara Almog, Zvi Nevo
For successful regeneration to occur following SCI, damage nerve cells must be replaced, and axons must regrow and find appropriate targets. Axons and their targets must then interact to construct synapses, the specialized structure that act as the functional connection between nerve cells. Recent neuroscientific advances, however, have led to new hope for conditions previously considered untreatable [34]. Regardless of the advances in cell therapy for SCI treatment revealing to be promising, cell transplantation for SCI often fails to yield functional recovery. When cell transplantation, without an effective medium support, are simply directly delivered into the injury site, an elevated percentage of cells does not survive due to the profound hypoxic and ischemic environment. Therefore, alternatives are needed in order to efficiently deliver cells and cell-based therapies within SCI sites [35]. The regenerative strategies using hydrogel to bridge the two segments of the injured spinal cord and provide a three-dimensional environment for the regenerating axons are very attractive. In line with this, the advantages of using hydrogel that support cell transplantation and axonal sprouting were highlighted. A number of hydrogels have been developed for SCI repair, including natural-based hydrogels such as alginate [36], agarose [37], collagen, and matrigel [38]. According to the reported findings, hydrogels may have a high therapeutic value for SCI treatment. Therefore, their future application for cell and/or drug delivery appears to be promising.
Increases in retinal nerve fiber layer thickness may represent the neuroprotective effect of cannabis: an optical coherence tomography study
Published in Journal of Addictive Diseases, 2020
Aysun Kalenderoglu, Mehmet Hamdi Orum, Ayse Sevgi Karadag, Ali Kustepe, Mustafa Celik, Oguzhan Bekir Egilmez, Dilay Eken-Gedik
The results of studies investigating the effect of substances on nerve cells are inconsistent. While some studies demonstrate that there are several changes, some have not reported changes.4,16–18 On the other hand, studies show that substance use can affect a developing brain in different ways.19 In the vast majority of substance users, it should be considered that the first substance used is cannabis, and that these first periods coincide with adolescence, in which brain development continues.20 In other words, most of the patients who were followed up with diagnoses of different substances were exposed to cannabis during adolescence.21 Therefore, it may be misleading to comment on the current substance diagnosis. In the literature, there are findings related to brain imaging of only cannabis users. Long-term cannabis use is hazardous to white matter in the developing brain. The use of cannabis may damage the brain’s connectivity and may lead to a variety of psychiatric disorders.7 Chronic users had significantly lower gray matter volumes in the right parahippocampal region while the corresponding left structure had higher white matter volumes.6 However, minimal evidence has been found to suggest an association between cannabis use and structural brain abnormalities. Although only current diagnoses were included in our study, it was considered that the group using cannabis did not have a history of another substance use due to general substance use characteristics.