小波变换在生物医学信号中的应用

小波变换是近年来发展起来的一种新的信号分析工具,本文结合生物医学信号与小波变换的特点,闸述了小波变换在生物医学信号特别是心电信号检测与去噪、图像增强和压缩中的应用及前景。     

基于小波变换和BP神经网络的视觉诱发电位识别

结合小波变换和BP神经网络对视觉诱发脑电信号（VEP）进行分类而产生脑机接口控制信号。利用一维离散小波变换提取强噪声背景下的低频微弱脑电信号，获取特征向量输入BP神经网络进行事件相关电位模式识别。实验表明，小波变换特征向量提取方法能有效地实现信号的去噪、降维和特征提取，BP神经网络能比较准确地从VEP中识别出事件相关电位，进行10次测试的平均识别正确率为99．375％，有利于产生脑机接口控制信号。     

Evidence that Oleic Acid Exists in a Separate Phase Within Stratum Corneum Lipids

Oleic acid is known to be a penetration enhancer for polar to moderately polar molecules. A mechanism related to lipid phase separation has been previously proposed by this laboratory to explain the increases in skin transport. In the studies presented here, Fourier transform infrared spectroscopy (FT-IR) was utilized to investigate whether or not oleic acid exists in a separate phase within stratum corneum (SC) lipids. Per-deuterated oleic acid was employed allowing the conformational phase behavior of the exogenously added fatty acid and the endogenous SC lipids to be monitored independently of each other. The results indicated that oleic acid exerts a significant effect on the SC lipids, lowering the lipid transition temperature (T _m) in addition to increasing the conformational freedom or flexibility of the endogenous lipid alkyl chains above their T _m. At temperatures lower than T _m, however, oleic acid did not significantly change the chain disorder of the SC lipids. Similar results were obtained with lipids isolated from the SC by chloroform:methanol extraction. Oleic acid, itself, was almost fully disordered at temperatures both above and below the endogenous lipid T _m in the intact SC and extracted lipid samples. This finding suggested that oleic acid does exist as a liquid within the SC lipids. The coexistence of fluid oleic acid and ordered SC lipids, at physiological temperatures, is consistent with the previously proposed phase-separation transport mechanism for enhanced diffusion. In this mechanism, the enhanced transport of polar molecules across the SC can be explained by the formation of permeable interfacial defects within the SC lipid bilayers which effectively decrease either the diffusional path length or the resistance, without necessarily invoking the formation of frank pores.     

Image analysis of soft-tissue in-growth and attachment into highly porous alumina ceramic foam metals

The detailed quantitative characterization of soft-tissue in-growth into highly porous artificial implants is critical to understanding the biophysical processes that will lead to the best structural scaffolding construct. Previous studies have performed mechanical peel tests and mostly qualitative histological analyses of soft-tissue. The goal of this paper is to report the results obtained from applying two image analysis algorithms to quantify the morphological structure found in histological images of stained soft-tissue in-growth into alumina ceramic foam metal implants using a canine model. Three different pore sizes were used and three different post-operative time points were considered. Using the 2D Wavelet Transform Modulus Maxima method and 2D Fourier Transform analysis, a strong anisotropic signature (directional preference) is detected in early (4-week) histological samples. The direction of preference is towards the center of the implants. The strength of the anisotropy at later time points (8 and 16 weeks) becomes gradually weaker. Our interpretation is that after a short period of time, the main tissue growth activity has been concentrated on filling the artificial implant by growing towards its center. The weaker anisotropic signature found at later time points is interpreted as the tissue growth activity strengthening its structure by growing in more random directions.     

浅议新任护士长的角色转化

护士长是医院管理的中坚力量,肩负着护理行政管理、业务管理、护理教学等责任。这就决定了她们的多角色功能,本文从新任护士长的岗前培训,强化其学习理念,培养其应变、观察能力,强化团队意识方面进行了探讨,以使其尽快进入角色。     

自身化学离子化/傅里叶变换质谱法研究蝙蝠葛碱和蝙蝠葛苏林碱及其衍生物的结构

采用自身化学离子化/傅里叶变换质谱(SCI/FTMS)技术研究了蝙蝠葛碱和蝙蝠葛苏林碱及这二个化合物的9个衍生物,由[M 1]准分子离子峰和特征碎片峰的质谱数据鉴定了这些衍生物的结构。     

Signal processors in duplex sonography: in vitro comparison between analog and digital methods

Using a new flow-test phantom, which respects the acoustic properties of real blood as well as the proximal and distal impedances of body circulation, we assessed the performance of two duplex sonography signal processors on blood-flow measurements. With both the analog and the dynamic signal processor (Fast Fourier Transform), the correlation between duplex sonography and quantitative flow measurements was high (0.96–0.99) for different dynamic conditions (steady or pulsatile blood flow, varying heart rate, blood pressure, and hematocrit) and for different mechanical conditions (silicon tube or animal vessel). The real blood flow was overestimated by duplex sonography the over-estimation was more pronounced with the analog processor (factor 1.87–4.20) than with the digital processor (factor 1.22–1.64,P<0.05). Applied to the study of asymmetric stenoses, the digital processor was not superior to the analog processors described in the literature.     

付里叶变换激光拉曼光谱在高分子及生物材料结构研究中的应用

普通激光拉曼光谱的用途一直受到激光诱导荧光的困扰,解决荧光干涉问题的一个有效方法是用近红外激发的付里叶变换拉曼光谱(FT-Raman)。作为一种非破坏性的分析技术,FT-Raman在对高分子物质、复杂的生物物质等的研究中有广泛的应用。本文综述了某些高分子物质如聚氨酯弹性体、聚酰亚胺以及一些生物物质如小鸡腿骨、正常人及白内障患者的眼睛晶状体等的FT-Raman光谱图和普通拉曼光谱图,并列出了这些物质的特殊拉曼线。     

Diagnosing Aortic Valve Stenosis by Parameter Extraction of Heart Sound Signals

The objective of this study was to develop an automatic signal analysis system for heart sound diagnosis. This should support the general practitioner in discovering aortic valve stenoses at an early stage to avoid or decrease the number of surgical interventions. The applied analysis method is based on classification of heart sound signals utilising parameter extraction. From the wavelet decomposition of a representative heart cycle as well as from the Short Time Fourier Transform (STFT) and the Wavelet Transform (WT) spectra new time series were derived. In several segments, parameters were extracted and analysed. In addition, features of the Fast Fourier Transform (FFT) of the raw signal were examined. In this study, 206 patients were enrolled, 159 with no heart valve disease or any other heart valve disease but aortic valve stenosis and 47 suffering from aortic valve stenosis in a mild, moderate or severe stage. To separate the groups, a linear discriminant function analysis was applied leading to a reduced parameter set. The introduced two classification stage (CS) system for automatic detection of aortic valve stenoses achieves a high sensitivity of 100% for moderate and severe aortic valve stenosis and a sensitivity of 75% for mild aortic valve stenosis. A specificity of 93.7% for patients without aortic valve stenosis is provided. The developed method is robust, cost effective and easy to use, and could, therefore, be a suitable method to diagnose aortic valve stenosis by general practitioners.     

Silymarin protects PBMC against B(a)P induced toxicity by replenishing redox status and modulating glutathione metabolizing enzymes—An in vitro study

PAHs are a ubiquitous class of environmental contaminants that have a large number of hazardous consequences on human health. An important prototype of PAHs, B(a)P, is notable for being the first chemical carcinogen to be discovered and the one classified by EPA as a probable human carcinogen. It undergoes metabolic activation to QD, which generate ROS by redox cycling system in the body and oxidatively damage the macromolecules. Hence, a variety of antioxidants have been tested as possible protectors against B(a)P toxicity. Silymarin is one such compound, which has high human acceptance, used clinically and consumed as dietary supplement around the world for its strong anti-oxidant efficacy. Silymarin was employed as an alternative approach for treating B(a)P induced damage and oxidative stress in PBMC, with an emphasis to provide the molecular basis for the effect of silymarin against B(a)P induced toxicity. PBMC cells exposed to either benzopyrene (1 μM) or silymarin (2.4 mg/ml) or both was monitored for toxicity by assessing LPO, PO, redox status (GSH/GSSG ratio), glutathione metabolizing enzymes GR and GPx and antioxidant enzymes CAT and SOD. This study also investigated the protective effect of silymarin against B(a)P induced biochemical alteration at the molecular level by FT-IR spectroscopy. Our findings were quite striking that silymarin possesses substantial protective effect against B(a)P induced oxidative stress and biochemical changes by restoring redox status, modulating glutathione metabolizing enzymes, hindering the formation of protein oxidation products, inhibiting LPO and further reducing ROS mediated damages by changing the level of antioxidant enzymes. The results suggest that silymarin exhibits multiple protections and it should be considered as a potential protective agent for environmental contaminant induced immunotoxicity.