The Effect Of Microbubble Cavitation On Rat Microvessel Structure And Its Significance

Cavitations occur regularly when ultrasound act on microbubble during the ultrasound microbubble technology application. On one hand, the cavitation supplies the acoustic signal for ultrasound diagnosis. On the other hand, the cavatition follow microbubble cavitation is the essential of many kinds of new application of ultrasound microbuble technology. Different kind of cavitations, stable or unstable cavitation, happens as different acoustic pressure act on the microbubble. At higher acoustic pressure, microbubble fragmentation, and unstable cavitation, also called inertial cavitation occurs. A lot of power is released when the microbubble rupture, which caused all kinds of effect on the nearby cell or tissue.We should control the extent of the damage induced by microbble cavitation freely when we use the technology of ultrasound microbubble on different purpose. In diagnosis use, the injure might as mild as possible. During gene transfection, the ruptures not only allow the macromolecular enter the cell through membrane, or pass through the endothelium barrier into tissue, but also do not induce serious subsequence. The injure cause cell or tissue regression is longed for in tumor therapy.Objective:To evaluate the safety of albumin microbubble used in diagnosis, we observed the state of injured microvessel caused by albumin microbubble destructed by diagnosis or therapy used ultrasound. To define the mechanism of intravascular gene transport by ultrasound microbubble, we observed the ruptured microvessel caused by ultrasound microbubble by electronic microscope, Propidium Iodide stain, and fluorescent polymer microspheres extraction. To investigated the change of microvessel structure by looking into the petechia at different time by electronic microscope. By observing theinfluence of different ultrasound microbubble condition on the extent of petechiae, intent to optimize the ultrasound microbuble induced intravascular gene transport condition primarily, and supply ultrasound microbuble parameter for in-vivo gene transfection.Method:1 The effect of albumin microbubble cavitation on the rat spinotrapezius microvessel structureAfter microbubble infusion, ultrasound was applied to the exteriorized spinotrapezius directly or to the intact rat spinotrapezius percutaneous by Sequoia 512 at the highest mechanical of different mode or ultrasound therapy device at different output. The changes of the structure of the spinotrapezius microvessel were observed by microscope under transillumination. The tissue slices were observed by microscope.2 The mechanism of microbubble cavitation induced intravascular gene transportSeveral frames of ultrasound were delivered to exteriorized spinotrapezius by a therapy ultrasound device directly. And petechias were induced by microbubble cavitation in the exteriorized spinotrapezius. The structure of the injured vessel structure was investigated by electronic microscope, Propidium Iodide stain, and fluorescent polymer microspheres extraction. The changes of microvessel structure were looked into at different time by electronic microscope.3 The influence of ultrasound or microbubble variables on microbubble cavatitionInfluence of ultrasound or microbubble variables on microvessel injure was observed by changing ultrasound output, ultrasound delivery time, microbubble infusion speed, pulsing interval, injection site, and different microbubble.Result:1 Diagnosis ultrasound delivery to spinotrapezius in-vivo or to intact rat spinotrapezius does not induced petechiae, no matter by the style of 2-D or PW in biggest mechanical index. No microvessel or tissue injure were found by microscope.2 No petechiae were caused by the therapy ultrasound device when the transducer output under 0.5 W cm-2. No microvessel or tissue injure were found by microscope. The therapy ultrasound device does induce petechiae in exteriorized spinotrapezius when the transducer output is above 0.75 W cm-2. The destructions of vessel were seen in capillaries and microvein. The threshold of tran...