基于FHT和MSBP的CT图像滤波反投影重建方法设计

滤波反投影算法（FBP）是商用CT系统中广泛使用的图像重建方法。在CT图像重建应用的场合，投影数据和目标函数都属于实数空间范畴。基于Fourier变换的重建方法涉及大量复数运算，是其在计算上的一个固有特点。与Fourier变换相比，Hartley变换以其实值变换的特点，在实数域能够替代Fourier变换，进行信号和图像的处理。MSBP方法是基于重建图像像素和投影射线之间在不同的投影方位上所存在的几何关系而提出的。将快速Hartley变换（FHT）算法和MSBP方法应用于CT图像的滤波反投影重建方法中，在保持精度不变的前提下，减少了所需的存储空间和计算量。     

Rho kinase as a novel molecular therapeutic target for hypertensive internal anal sphincter

BACKGROUND & AIMS: An increase in Rho kinase (ROK) activity has been associated with agonist-induced sustained contraction of the smooth muscle, but its role in the pathophysiology of spontaneously tonic smooth muscle is not known. METHODS: Present studies examined the effects of ROK inhibitor Y-27632 in the tonic smooth muscle of the rat internal anal sphincter (IAS) versus in the flanking phasic smooth muscle of the rectum. In addition, studies were performed to determine the relationship between the decreases in the basal IAS tone and the ROK activity. Confocal microscopic studies determined the cellular distribution of the smooth muscle-predominant isoform of ROK (ROCK-II) in the smooth muscle cells (SMCs). RESULTS: In in vitro studies using neurohumoral inhibitors and tetrodotoxin and the use of SMCs demonstrate direct relaxation of the IAS SMCs by Y-27632. The ROK inhibitor was more potent in the IAS than in the rectal smooth muscle. The IAS relaxation by Y-27632 correlated specifically with the decrease in ROK activity. Confocal microscopy revealed high levels of ROCK-II toward the periphery of the IAS SMCs. In in vivo studies, the lower doses of Y-27632 caused a potent and selective decrease in the IAS pressures without any adverse cardiovascular systemic effects. The ROK inhibitor also caused potent relaxation of the hypertensive IAS. CONCLUSIONS: RhoA/ROK play a crucial role in the maintenance of the basal tone in the IAS, and ROK inhibitors have a therapeutic potential in the IAS dysfunction characterized by the hypertensive IAS.