Cerebral saccular aneurysm is a major cause of subarachnoid hemorrhage, one of the cerebrovascular diseases with the highest mortality. The mechanisms underlying the development of aneurysm, however, still remain unclear. We have made a series of reports on an animal model of experimentally induced cerebral aneurysms, which resemble human cerebral aneurysms in their location and morphology. The objective of this brief review is to introduce our evidence about the pathogenesis of cerebral aneurysms using the experimentally induced cerebral aneurysm model, particularly focused upon the role of NO and shear stress on degenerative changes of the arterial wall during the aneurysm development.
In our model, cerebral aneurysms are induced in rats, monkeys, and mice by ligation of unilateral common carotid artery and renal hypertension, suggesting that an increase in hemodynamic stress is a key requirement for the aneurysm development. Our morphological and molecular studies suggest that increased wall shear stress, iNOS-derived NO, MMP-2 & 9, cathepsin B, NF-κ B, interleukin-1 β, and endothelin B receptor are associated with the progression of cerebral aneurysms. Statin and Nifedipine may be possible drugs for the prevention of cerebral aneurysm development.

抄録全体を表示

The micro bubbles shows interesting phenomena in the ultrasonic wave and these phenomena have been studied especially in physics and chemical field. Recently, micro bubbles with diameter less than a few micro meters, which are safe to living body, have been fabricated. These micro bubbles are used as contrast agent in the field of medical ultrasonics and many distinctive medical diagnoses have been developed. In this paper, first, the bubble dynamics in the ultrasonic wave are presented. The bubble shows nonlinear volumetric oscillation when the sound pressure of the ultrasonic wave is relatively high. It is destructed when high intensity ultrasonic wave is applied. An acoustic radiation force is produced to the oscillating micro bubbles in the ultrasonic wave field. By these features, it is considered that the micro bubble may be a sophisticated payload vehi-cle in the drug delivery system or in the gene delivery system. Sonoporation, which is a method to make micro pores of cell membrane by bubble destruction, is expected to be an useful method for dose improvement in the future drug or gene delivery system. In this paper, some methods, which are developed for micro bubble targeting at the required position against the flow, are reviewed.

抄録全体を表示