RESUMO
Blood-brain barrier (BBB) disruption underlies the vasogenic edema and neuronal cell death induced by acute ischemic stroke. Reducing this disruption has therapeutic potential. Transcranial focused ultrasound stimulation has shown neuromodulatory and neuroprotective effects in various brain diseases including ischemic stroke. Ultrasound stimulation can reduce inflammation and promote angiogenesis and neural circuit remodeling. However, its effect on the BBB in the acute phase of ischemic stroke is unknown. In this study of mice subjected to middle cerebral artery occlusion for 90 minutes, low-intensity low-frequency (0.5 MHz) transcranial focused ultrasound stimulation was applied 2, 4, and 8 hours after occlusion. Ultrasound stimulation reduced edema volume, improved neurobehavioral outcomes, improved BBB integrity (enhanced tight junction protein ZO-1 expression and reduced IgG leakage), and reduced secretion of the inflammatory factors tumor necrosis factor-α and activation of matrix metalloproteinase-9 in the ischemic brain. Our results show that low-intensity ultrasound stimulation attenuated BBB disruption and edema formation, which suggests it may have therapeutic use in ischemic brain disease as a protector of BBB integrity.
RESUMO
Degradation effect of organic pollutant on pentachlorophenol (PCP) is researched by ultrasound. PCP is treated by low frequency (16 kHz) and high frequency (800 +/- 1 kHz), and bi-frequency. The results of investigation on the ultrasonic destruction of PCP showed that the rate of PCP degradation at the same conditions is the highest at bi-frequency, and the lowest at 16 kHz. In the presence of Fenton type reagent the degradation rate of PCP is the highest at bi-frequency (20.93 times) as compared to the stirring system. This ratio is 4.91 and 1.06 at 800 kHz and 16 kHz, respectively. The studies showed the bi-frequency is an effective method for pollutants degradation, but it is need make further study. Taking 800 kHz for example, under the same conditions, the smaller pH of the solution, the higher is the reaction rate. A similar situation applied to TOC, but the TOC removal lags behind degradation of PCP. This indicated the PCP is not completely mineralized. The ultrasound is somewhat enhanced for degradation of PCP and mineralization with only addition of CuSO4, but the combination of ultrasound and Fenton type reagent is effective method for PCP degradation and mineralization. The rate of PCP degradation and TOC removal appeared to follow pseudo-first-order reaction kinetic law.