Fast Adaptive Unsharp Masking with Programmable Mediaprocessors

Unsharp masking is a widely used image-enhancement method in medical imaging. Hardware-based solutions can be developed to support high computational demand for unsharp masking, but they suffer from limited flexibility. Software solutions can easily incorporate new features and modify key parameters, such as filtering kernel size, but they have not been able to meet the fast computing requirement. Modern programmable mediaprocessors can meet both fast computing and flexibility requirements, which will benefit medical image computing. In this article, we present fast adaptive unsharp masking on two leading mediaprocessors or high-end digital signal processors, Hitachi/Equator Technologies MAP-CA and Texas Instruments TMS320C64x. For a 2k × 2k 16-bit image, our adaptive unsharp masking with a 201 × 201 boxcar kernel takes 225 ms on a 300-MHz MAP-CA and 74 ms on a 600-MHz TMS320C64x. This fast unsharp masking enables technologists and/or physicians to adjust parameters interactively for optimal quality assurance and image viewing.     

An ER export signal accelerates the surface expression of shal potassium channels in pyloric neurons of the lobster stomatogastric ganglion

The shal gene encoding the transient potassium current, I _A, plays important roles in shaping the firing properties of neurons in the pyloric network in the stomatogastric ganglion (STG) of the spiny lobster, Panulirus interruptus. However, when we overexpressed the shal protein in pyloric dilator (PD) neurons, the effect of increased I _A was compensated by a parallel upregulation of the hyperpolarization activated inward current (I _h). In an attempt to temporally separate the overexpression of shal from the compensatory up-regulation of I _h channels, we inserted an endoplasmic reticulum (ER) export signal sequence, FCYENE, into the shal gene. This signal sequence accelerated the surface expression of shal protein in Xenopus oocytes and PD neurons. However, the accelerated expression of shal still did not alter the firing properties of the injected neuron, suggesting that the compensatory upregulation of I _h occurs simultaneously with the upregulation of I _A.     

Methods for non-invasive detection of ventricular late potentials--a comparative multicenter study

To evaluate the methodological problems of the non-invasive registration of late potentials the results obtained with four different averaging devices in the same 109 patients were compared. The high-resolution ECG was obtained from the body surface, high-gain amplified and filtered. With the averaging technique, the improved signal-to-noise ratio was able to detect low-amplitude cardiac activity. The incidence of late potentials detected with the four averaging systems, whose characteristics are described, ranged between 12% and 21%. Corresponding positive results were obtained in 5.5%, corresponding negative results in 68.8%. The reasons for differing results were mainly due to differences in visual or automatic interpretation of the registered fractionated electrical cardiac activity. Additionally, the determination of the end of QRS using the QRS width, obtained from reference leads, may influence the specificity of the methods.     

数字信号处理技术在医学物理实验中的应用

信息社会的发展,在很大程度上取决于信息与信号处理技术的先进性.数字信号处理技术的出现改变了信息与信号处理技术的整个面貌,测量仪器技术与计算机技术深层次的结合正引起测试仪器领域里一场新的革命,一种全新的仪器结构概念导致了新一代仪器--虚拟仪器的出现,它是现代计算机技术、通信技术里测量技术相结合的产物,是传统仪器观念的一次巨大变革.它的出现使得人类的测试技术进入了一个新的发展纪元.本文介绍了用"弱电与非电信号处理系统"这一虚拟仪器进行生物非电信号的采集和分析的应用过程.     

人工神经网络预滤波的自适应运动心电信号增强器

运动心电图是一种将人体对象置于非平静状态下检测到的心电信号，其特点是运动导致基线严重漂移，肌电干扰显著增加，信噪比低。介绍了一种用人工神经网络预滤波的自适应运动心电信号增强器。运用人工神经网络的非线性和自适应处理的跟踪特性有机地结合设计而成。能降低噪声，提高信噪比，有效地提取运动心电信号。     

计算机辅助的心血管信号检测和处理系统的研究

【目的】研制一个计算机辅助的心血管信号检测和处理系统。【方法】本系统的硬件设计采用奔腾 Ⅱ / 2 33多媒体微机系统 ,多路模 /数转换器和心电电极、心音传感器、脉搏波传感器及由运算放大器等构成相关的放大器及滤波器。本系统采用可视化编程环境构建系统结构和功能模块设计的方法 ,基于多媒体技术和小波变换原理 ,在 32位Windows平台下 ,利用可视化编程语言VisualC 6 0和多媒体著作工具Authorware等进行系统的软件设计。【结果】本系统能完成心电、心音、脉搏波信号检测和处理 ,并将结果以图、文、声并茂的形式显示、打印或播放 ,还具有病案管理和心音听诊多媒体计算机辅助教学功能。【结论】它是一个新型的多功能心血管信号检测和处理系统。     

CARD In Situ Hybridization: Sights and Signals

During the last decade, several strategies have been developed to improve the detection sensitivity ofin situ hybridization (ISH) by amplification of either target nucleic acid sequences prior to ISH (e.g.,in situ PCR), or the detection signals after the hybridization procedures (signal amplification). Here we outline the principles of tyramide signal amplification using the catalyzed reporter deposition (CARD) technique, summarize applications as well as possible limitations of CARD ISH, and discuss some future directions ofin situ nucleic acid detection using this amplification strategy.     

KP544 amplifies the effects of nerve growth factor on cell differentiation and is neuroprotective

The ability of endogenous neurotrophins, including nerve growth factor (NGF), to promote the survival and development of neurons provides convincing evidence for their therapeutic potential, despite significant barriers to their successful clinical use. Many of these barriers might be surmountable, however, by strategies that enhance endogenous neurotrophin signaling. We evaluated a series of substituted pyrimidines for their ability to enhance the effects of NGF. KP544 [2‐amino‐5‐(4‐chlorophenylethynyl)‐4‐(4‐trans‐hydroxycyclohexylamino) pyrimidine] amplified NGF‐induced neurite outgrowth of PC12 cells approximately 2‐fold at 2 µM. KP544 also enhanced choline acetyltransferase activity, a marker of differentiation induced by either NGF or by cyclic AMP, by 3‐ to 8‐fold, with a 2‐fold amplification at 0.12–0.3 µM. This amplification occurred at all concentrations of NGF used including those that maximally stimulated the cells. KP544 did not increase the levels of phosphorylated mitogen‐activated protein kinases (MAPK) above that seen with NGF alone. These studies suggested that KP544 functions within the cell at a site that is downstream from or independent of MAPK signaling. NGF‐induced neurite outgrowth in a human cell line (SH‐SY5Y neuroblastoma cells) was also enhanced with KP544 treatment. Primary embryonic rat cortical cultures were used to extend the observations beyond the studies with the immortalized cell lines. In addition to effects on neurite outgrowth, KP544 protected these cells from glutamate‐induced death. Overall, the data suggest that KP544 can selectively interact in the differentiation pathway downstream of MAPK in a manner that amplifies nerve growth factor and cyclic AMP effects and is also neuroprotective. Drug Dev. Res. 62:49–59, 2004. © 2004 Wiley‐Liss, Inc.