RESUMEN
The 4-layer sphere model of human head was built; the layers from outside to inside represented the scalp, the skull, the CFS and the brain, respectively. The point current source placed on the outmost layer was regarded as the boundary condition, and the method of separation of variables was used to solve the equations. The potential distribution and the current expression were given, and the isopotential-line map and current lines were drawn. The simulation result can be used to analyze head EIT problems.
Asunto(s)
Humanos , Algoritmos , Encéfalo , Fisiología , Simulación por Computador , Impedancia Eléctrica , Electrodos , Fenómenos Electromagnéticos , Cabeza , Fisiología , Interpretación de Imagen Asistida por Computador , Métodos , Modelos Teóricos , Pletismografía de Impedancia , Métodos , Tomografía , MétodosRESUMEN
Objective To investigate the effect of preconditioning through stimulation of the fastigial nucleus (FNS)on the expression of matrix metalloproteinase-9 after cerebral ischemia. Methods A total of 312 male Wistar rats were divided randomly into three groups:a control group,a sham-FNS group and a FNS group.All the rats in the sham-FNS and FNS groups were subjected to middle cerebral artery occlusion(MCAO)by using a thread to occlude the right middle cerebral artery,while those in the control group were subject only to a similar operative procedure without real MCAO.Twenty-four hours before the operation,all the rats in the FNS group were given 1 hour of preconditioning FNS,while those in the sham-FNS group was given sham-FNS.Individuals were sacrificed at the 6th,12th,24th,and 72nd hour after MCAO.The brain water content was measured by the dry-wet weight method.The blood-brain barrier(BBB)permeability was measured using Evan's blue.MMP-9 protein expression was measured by Western blotting.Results The water content in the ischemic brain tissue,the BBB permeability and the expression of MMP-9 were all found to be significantly higher in the sham-FNS group than in the control group.Compared with the sham-FNS group,the brain water content and BBB permeability were significantly lower in the FNS group,while M MP-9 protein expression also decreased significantly.Conclusion FNS preconditioning can inhibit MMP-9 expression,thereby relieving BBB permeability and ischemic brain edema.
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The key technologies of sweep-frequency electrical impedance tomography system are presented in detail, which consist of the ones for the excitation signal source, constant current source, analog switch array and signal demodulation. A data acquisition system of sweep-frequency electrical impedance tomography based on high-speed composite-signal (ISP-FLASH) MCU is designed. High-speed composite-signal (ISP-FLASH) MCU is applied to electrode gating, data acquisition and data communication with PC. PC is adopted as the master computer to control inferior devices, receive measurement data and perform image reconstruction. The problem and possible way to develop the measurement system are also mentioned.
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This article discusses the composing of the rise-and-fall sickbed which is based on infrared remote control technology, the design and working principle of the sickbed mechanical structure and the design and working principle of the infrared remote control circuit. It is convenient, reliable, endurable and cheap.