Outcomes After Aortic Valve Replacement for Asymptomatic Severe Aortic Regurgitation and Normal Ejection Fraction

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基于LVQ的自发脑电信号的分类研究

为了识别在不同思维状态下的自发脑电(EEG)信号，本文用6阶自回归(AR)模型表示EEG信号，用学习矢量量化(LVQ)神经网络作分类器，分别用LVQl和LVQ2．1算法对网络进行训练，并对分类结果进行测试，比较了网络选择不同参数时对分类正确率的影响。研究表明：竞争层神经元数目直接影响了正确率，当选择最佳参数值时分类正确率为62％-83％，因人而异。     

Developmental characteristics of topographic EEG in the newborn using an autoregressive model

Summary Autoregressive topographic EEG analysis was used to determine topographic EEGs of the total power in quiet and active sleep stages in 33 healthy premature infants of 34 to 40 weeks conceptional age. The developmental characteristics were also examined by simultaneously referring to the autoregressive pattern discrimination of topographic EEGs between different conceptional age groups in both sleep stages. Treating 10.24 seconds of EEG as one segment, the topographic EEG of 10 segments in each of the quiet and active sleep stages as well as their mean were obtained. In both sleep stages the results showed a small peak in total power in the frontal region and a large peak in the occipital region, but total power was greater in the quiet sleep. Total power decreased with increasing conceptional age. Topographic pattern discrimination between different conceptional age groups showed significant differences mainly in the frontal, temporal and occipital regions. It was concluded that regional differences in the development of EEG in premature infants could be clarified by means of topographic EEG analysis and the pattern discrimination method using the autoregressive model.This study was supported by a Scientific Research Grant (No. 02670450) from the Japanese Ministry of Education.     

Mdm2、Bc1-2、AR在良性脑膜瘤中表达的关系

目的研究凋亡相关蛋白mdm2、bcl-2和AR（雄激素受体）之间的关系，为脑膜瘤的性激素对抗治疗提供一些新信息。方法从华西医院病理科获得04年1月-07年12月病理诊断明确的脑膜瘤共394例，计算机随机抽样60例，其中良性脑膜瘤（WH0I）41例，用LsAB法做免疫组化染色，检测mdm2、bcl-2、AR的表达。结果在良性脑膜瘤中mdm2、bcl-2、AR的表达率分别为67％、62％、33％，三者之间没有相关关系。结论（1）是否能够作为抗性激素治疗疗效的筛选和／或预测指标，bcl-2比mdm2更有潜在价值。（2）AR在脑膜瘤中的促进生长作用的相对独立性，提示AR可以作为脑膜瘤对抗激素治疗的新靶点进一步研究。     

基于EEG信号AR模型的中枢神经系统损伤检测

本文综述一类基于 EEG信号 AR谱和 AR模型参数分析的中枢神经系统损伤检测方法 ,包括主控频率法、AR谱距离法和 Itakura距离测度法等。这类方法根据 EEG信号的 AR模型建立分析 EEG信号状态和变化的测度 ,并利用其检测中枢神经系统在缺氧窒息实验过程中可能存在的损伤并预测最终结果。实验和数据分析的结果表明 ,这类方法在实验各个阶段的检测结果与采用医学方法进行综合评价的 NDS结果一致 ,具有较高的可靠性。     

用自回归白化滤波器提取脑-机接口信号VEP

利用脑-计算机接口这种新颖的人-机交互模式构建一种脑控拼写装置,其主要问题是实时、准确地从头皮电极记录到的脑电背景信号中提取视觉诱发电位,以决定用户选择按键。由于在一个短时程内可以认为自发脑电是平稳的,利用靶刺激出现前记录到的非靶刺激信号计算自回归模型参数,构造一个白化滤波器,再将实时信号通过白化滤波器滤波,使自发脑电得以白化,然后采用小波分析方法滤除白噪信号。结果表明靶刺激信号更加突出,提高了后续模式分类的正确率。采用模拟自然阅读诱发模式使短时信号的平稳性得到了保障,利用白化滤波器去除自发脑电是可行的。     

Analysis of EEG signals during epileptic and alcoholic states using AR modeling techniques

Electroencephalogram (EEG) analysis remains problematic due to limited understanding of the signal origin, which leads to the difficulty of designing evaluation methods. In spite of these shortcomings, the EEG is a valuable tool in the evaluation of some neurological disorders as well as in the evaluation of overall cerebral activity. In most studies, which use quantitative EEG analysis, the properties of measured EEG are computed by applying power spectral density (PSD) estimation for selected representative EEG samples. The sample for which the PSD is calculated is assumed to be stationary. This work deals with a comparative study of the PSD obtained from normal, epileptic and alcoholic EEG signals. The power density spectra were calculated using fast Fourier transform (FFT) by Welch's method, auto regressive (AR) method by Yule–Walker and Burg's method. The results are tabulated for these different classes of EEG signals.     

大鼠脑损伤后GABA及其受体GABAAR的变化

目的 探讨GABA及其受体GABAAR在创伤性脑损伤（TBI）后的变化规律及其在继发性脑损害中的作用。方法 用大鼠颅脑打击伤动物模型、免疫组织化学方法,观察了致伤后不同时相大鼠伤侧及对侧皮层、海马的GABA及GABAARα2阳性神经元的表达变化。结果 致伤后伤侧皮层GABA／GABAARα1阳性神经元逐渐减少,12h降至最低,对侧皮层无改变;伤侧海马及对侧海马GABA阳性神经元逐渐减少,12h降至最低;伤侧海马GABAARα1的改变与GABA的改变一致,对侧海马无改变。结论 TBI后脑内抑制性神经递质GABA及其受体GABAAR的表达下调也可能是继发性脑损害的重要因素之一。     

学龄儿童β3-肾上腺素能受体基因变异的分布

目的 了解学龄儿童中β3-肾上腺索能受体（β3-AR)基因氧基酸序列第64位密码子上的色氨酸(Trp64Arg)变异型的分布特点及其与肥胖的关系，方法 用限制性片段基困长度多态性法对177名儿蛊进行了基因多态性检测，同时测量身高、体重。结果 变异型等位基因(C)在被调查对象中出现的频率为0．240，其中男童为0226，女童为0．267。肥胖女童中变异等位基因(C)、Trp64Arg变异基因型的出现频率明显高于正常体重者。有父母肥胖或有母亲肥胖的家庭中，女童出现Trp64Arg变异的频率分别为713．3％，71．4％。具有Trp64Arg变异儿童的体重、BM1明显较高，具有Trp64Arg变异的女童发生肥胖的危险性为4．5，结论 基因Trp64Arg变异在学龄儿童中有一定的分布，且以肥胖女童为多。