Objective. A number of lumped and distributed parameter models of the inner ear have been proposed in order to improve the vestibular implant stimulation. The models should account for all significant physical phenomena influencing the current propagation: electrical double layer (EDL) and medium polarization. The electrical properties of the medium are reflected in the electrical impedance, therefore the aim of this study was to measure the impedance in the guinea pig inner ear and construct its equivalent circuit. Approach. The electrical impedance was measured from 100 Hz to 50 kHz between a pair of platinum electrodes immersed in saline solution using sinusoidal voltage signals. The Randles circuit was fitted to the measured impedance in the saline solution in order to estimate the EDL parameters (C, W, and Rct) of the electrode interface in saline. Then, the electrical impedance was measured between all combinations of the electrodes located in semicircular canal ampullae and the vestibular nerve in the guinea pig in vitro. The extended Randles circuit considering the medium polarization (Ri, Re, Cm) together with EDL parameters (C, Rct) obtained from the saline solution was fitted to the measured impedance of the guinea pig inner ear. The Warburg element was assumed negligible and was not considered in the guinea pig model. Main results. For the set-up used, the obtained EDL parameters were: C=27.09*10-8 F, Rct=18.75 kΩ. The average values of intra-, extracellular resistances, and membrane capacitance were Ri=4.74 kΩ, Re=45.05 kΩ, Cm=9.69*10-8 F, respectively. Significance. The obtained values of the model parameters can serve as a good estimation of the EDL for modelling work. The EDL, together with medium polarization, plays a significant role in the electrical impedance of the guinea pig inner ear, therefore, they should be considered in electrical conductivity models to increase the credibility of the simulations.
We investigated the predictors of increased seizures’ frequency among women with various forms of idiopathic generalized epilepsies (IGE) in the gestational and postgravid period. We observed 41 patients with Idiopathic generalized epilepsy (IGE) before, during and after pregnancy. During the period of observation EEG was recorded in the states of relaxed and active awakeness and sleeping. Patients, who have stopped to take anticonvulsants before pregnancy, have had increased frequency of seizures, more than1 ina year, with interictal epileptiform discharges in a state of relaxed and active awakeness. Increased seizures after pregnancy was observed in patients with interictal epileptiform discharges during sleep. The results can be used during the preparation of pregravid women with IGE.
В экспериментах на крысах изучали влияние пептида глицилпролина (Gly-Pro) на стимулированную карбахолом секреторную активность желудка в условиях многокомпонентного стресса. Воздействие стрессирующих факторов (иммобилизация, оперативное вмешательство, процедура инъекции) в различных сочетаниях и последовательности сопровождалось формированием 3 типов ответных реакций желудка на холинергическую стимуляцию его секреции: нормергический, гипоергический и гиперергический. Gly-Pro модулирует холинергические влияния на желудочную секрецию в условиях многокомпонентного стресса, формируя нормергический уровень активности органа у всех животных. Исследование пептида выявило границы нормы реакции разных показателей желудочной секреции у крыс.
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