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Electrophysiological devices are connected to the body through electrodes. In some applications, such as nerve stimulation, it is needed to minimally pierce the skin and reach the underneath layers to bypass the impedance of the first layer called stratum corneum. In this study, we have designed and fabricated surface microneedle electrodes for applications such as electrical peripheral nerve stimulation. We used molybdenum for microneedle fabrication, which is a biocompatible metal; it was used for the conductive layer of the needle array. To evaluate the performance of the fabricated electrodes, they were compared with the conventional surface electrodes in nerve conduction velocity experiment. The recorded signals showed a much lower contact resistance and higher bandwidth in low frequencies for the fabricated microneedle electrodes compared to those of the conventional electrodes. These results indicate the electrode-tissue interface capacitance and charge transfer resistance have been increased in our designed electrodes, while the contact resistance decreased. These changes will lead to less harmful Faradaic current passing through the tissue during stimulation in different frequencies. We also compared the designed microneedle electrodes with conventional ones by a 3-dimensional finite element simulation. The results demonstrated that the current density in the deep layers of the skin and the directivity toward a target nerve for microneedle electrodes were much more than those for the conventional ones. Therefore, the designed electrodes are much more efficient than the conventional electrodes for superficial transcutaneous nerve stimulation purposes.

Background: There is evidence that supports the neuroprotective effects of dimethyl fumarate (DMF) in stroke. Nuclear factor erythroid 2-related factor 2 (Nrf2) has both anti-oxidant and anti-inflammatory mechanisms. We investigated the neuroprotective effects of DMF via Nrf2 activation in the cortex, striatum, and diencephalon in a middle cerebral artery occlusion (MCAO) model of stroke. Methods: 22 Sprague-Dawley male rats were randomized into 3 groups. In DMF-treated group (n = 8), rats received 15 mg/kg oral DMF twice daily by gavage from day 0 to 14 after a 60-minute MCAO. The vehicle group (n = 7) underwent MCAO and were given methocel/H2O, using the same method and schedule. In the sham group (n = 7), neck was opened, but neither middle cerebral artery (MCA) was occluded nor any drug was administered. After 14 days, the animals were sacrificed. The infarct volume were assessed by stereology method. Nrf2 expression was evaluated in the cortex, striatum, and diencephalon by immunohistochemistry method. Results: Ratio of infarct to total brain volume was significantly lower in the DMF-treated group (5.76%) in comparison with the vehicle group (22.39%) (P < 0.0001). Nrf2 expression was higher in DMFtreated group in comparison with both the vehicle and sham groups in cortex, striatum, diencephalon, and total brain (P < 0.0001). In the DMF-treated group, significant negative correlation between Nrf2 expression and infarct volume was observed in cortex, striatum, diencephalon, and total brain. Conclusion: DMF induces Nrf2 expression and its neuroprotective effects in different brain anatomical regions.

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Background: Concussion symptoms typically resolve within 7–10 days, but 10–25% of patients do not fully recover. They can develop post-concussion syndrome (PCS), which includes sleep abnormalities such as obstructive sleep apnea. It is unclear how specific sleep problems manifest in PCS and how it relates to cognition and symptomology. Methods: A retrospective chart review was conducted on PCS patients seen at the University Health Network (UHN) Concussion Clinic and sent for sleep study. Neuropsychology tests, concussion features, PCS symptoms, and demographics were abstracted from clinical charts. Sleep measures were abstracted from the overnight sleep study. Data were analyzed using chi-squared tests and linear regression. Results: Fifty-one patients completed the sleep study; 78% of these were diagnosed with sleep apnea. Patients with sleep apnea reported significantly more memory symptoms. A trend existed for higher total symptom number. Age was significantly different between the two groups. Women and men were equally at risk of being diagnosed with sleep apnea. Conclusions: Sleep apnea is common in PCS patients complaining of non-restorative sleep and/or waking up with headaches. Sleep apnea was associated with more memory symptoms. PCS patients are at higher risk for sleep apnea and sleep study should be considered if complaining of non-restorative sleep and/or waking up with headaches, regardless of sex and other known risk factors.