64排螺旋CT下肢血管成像技术与DSA评估动脉狭窄的效果对比研究

目的探讨64排螺旋CTA评估下肢动脉狭窄闭塞性疾病的效果。方法对43例下肢动脉闭塞性疾病患者行64排螺旋CTA扫描,18例一周后行双下肢DSA检查,将每侧下肢血管分成8段,动脉狭窄程度分为：正常、轻度狭窄、中度狭窄、重度狭窄、闭塞5个级别。并以DSA为标准来评估。结果对18例患者双侧下肢共288段血管进行研究,CTA与DSA对血管狭窄程度显示一致的有275段,被CTA高估有ll段血管,低估有2段血管。结论64排螺旋CTA是下肢动脉狭窄硬化性疾病可靠的评估方法。     

便携式心电监护中实时信号处理方法研究

针对心电信号处理过程中的心电信号数字滤波、心电波形的动态显示、心电数据存储等问题,阐述了3个可用于心电信号实时处理的方法：一是运用滤波器频谱的周期性减少了滤波器系数个数,提高了运算速度,并根据卷积公式特点实现了数字滤波的实时性;二是运用基于内存虚拟屏幕技术实现心电波形动态显示,解决了屏幕闪烁和绘图不连续问题;三是采用嵌入式数据库SQLITE实现了心电数据存储。所有方法均考虑实时性要求,并已成功用于课题组开发的便携式心电监护仪,效果较为理想,具有很强的实用价值。     

两种数字化影像信息检测系统图像质量与辐射剂量的比较研究

目的对比研究平板探测器和影像板两种数字化影像信息检测系统图像质量与辐射剂量的关系。方法应用DR和CR系统分别对对比度-细节体模（CDRAD2．0）进行不同辐射剂量的曝光成像。记录每次曝光的模体表面辐射剂量,将所获取的影像用CDRAD 2．0评估软件分析计算图像质量因子反数值IQFinv,并应用Spearman相关性检验和Wilcoxon秩和检验进行分析,比较两种数字化影像信息检测系统图像质量与辐射剂量的差异。结果在管电流量不同mAs时,DR系统的IQFinv值与CR的IQFinv值差异有统计学意义（P〈0．05）。结论辐射剂量相同时,平板探测器对于低对比度细节的检测能力优于影像板;在获得相同的图像质量时,与CR相比应用DR大大降低了被检者辐射剂量。     

Selective pressures on genomes in molecular evolution

We describe the evolution of macromolecules as an information transmission process and apply tools from Shannon information theory to it. This allows us to isolate three independent, competing selective pressures that we term compression, transmission, and neutrality selection. The first two affect genome length: the pressure to conserve resources by compressing the code, and the pressure to acquire additional information that improves the channel, increasing the rate of information transmission into each offspring. Noisy transmission channels (replication with mutations) give rise to a third pressure that acts on the actual encoding of information; it maximizes the fraction of mutations that are neutral with respect to the phenotype. This neutrality selection has important implications for the evolution of evolvability. We demonstrate each selective pressure in experiments with digital organisms.     

Predicting the distribution of shrub species in southern California from climate and terrain-derived variables

Abstract. Generalized additive, generalized linear, and classification tree models were developed to predict the distribution of 20 species of chaparral and coastal sage shrubs within the southwest ecoregion of California. Mapped explanatory variables included bioclimatic attributes related to primary environmental regimes: averages of annual precipitation, minimum temperature of the coldest month, maximum temperature of the warmest month, and topographically-distributed potential solar insolation of the wettest quarter (winter) and of the growing season (spring). Also tested for significance were slope angle (related to soil depth) and the geographic coordinates of each observation. Models were parameterized and evaluated based on species presence/absence data from 906 plots surveyed on National Forest lands. Although all variables were significant in at least one of the species’ models, those models based only on the bioclimatic variables predicted species presence with 3–26% error. While error would undoubtedly be greater if the models were evaluated using independent data, results indicate that these models are useful for predictive mapping – for interpolating species distribution data within the ecoregion. All three methods produced models with similar accuracy for a given species; GAMs were useful for exploring the shape of the response functions, GLMs allowed those response functions to be parameterized and their significance tested, and classification trees, while some-times difficult to interpret, yielded the lowest prediction errors (lower by 3–5%).     

Quantitative analyses of cross-sectional shape of the distal radius in three species of macaques

I conducted quantitative analyses of the cross-sectional shape of the distal radial shaft in three species of macaques, which differ in locomotor behavior: semi-terrestrial Japanese macaques (Macaca fuscata), arboreal long tailed macaques (M. fascicularis), and relatively terrestrial rhesus macaques (M. mulatta). I took CT scans of the distal radial shafts of a total of 180 specimens at the level of the inferior radio-ulnar articulation. From each CT image, the periosteal outline of the radius was traced automatically by a digital imaging technique. I determined five points (landmarks) on the outline by developing a standardized morphometric technique. Bone surface lengths were measured by using these landmarks and their soft tissue correlates were investigated. The results of this study were as follows: (1) Semi-terrestrial M. fuscata has features that are approximately intermediate between those of the other two species. M. fuscata has a relatively small groove for M. abductor pollicis longus and a large groove for Mm. extensor carpi radialis longus et brevis. These characters resemble those of M. fascicularis. On the other hand, the ulnar notch of M. fuscata is relatively large, a character which is similar to that of M. mulatta. Moreover, compared to the other two macaques, the surface of the flexor muscles of M. fuscata is intermediate in size. (2) The more terrestrial M. mulatta has a relatively large groove for M. abductor pollicis longus and a small groove for Mm. extensor carpi radialis longus et brevis. Moreover, M. mulatta has a relatively large ulnar notch and a small surface for the flexor muscles. (3) The arboreal M. fascicularis has similar features to those of M. fuscata for the first and second relative size index. However, in the ulnar notch, M. fascicularis has a peculiar character and the surface for the flexor muscles is relatively large compared to those of the other two species. These results can be interpreted in terms of positional habits and presumed functional demands. A form-functional study by Lemelin and Schmitt also corroborates the interpretations of the present study. Thus, the distal region of the forearm strongly reflects muscular development and joint resultant force, and is an important region for investigating locomotor adaptations in primates. The present study reveals the possibility of using this type of morphometric analysis for reconstructing the positional behavior of fossil primates.     

Identification of novel tick salivary gland proteins for vaccine development

Methods currently used to control Ixodes scapularis ticks rely principally on acaricidal applications which suffer from a number of limitations. Recently, host vaccination against ticks has been shown to be a promising alternative tick control method. In tick salivary glands, numerous genes are induced during the feeding process. Many of these newly expressed proteins are secreted in tick saliva and may play a role in modulating host immune responses and pathogen transmission. We have performed suppression subtraction hybridization to identify unique I. scapularis salary gland proteins specifically expressed during engorgement. We have cloned and sequenced ten unique salivary gland-associated cDNAs that are up-regulated during feeding. The protein products of these genes represent potential vaccine candidates for use in the control of ticks and to prevent transmission of tick-borne diseases.     

Identification, sequence characterization, and analysis of expression profiles of three novel CC chemokines from domestic duck (Anas platyrhynchos)

Chemokines are low-molecular weight-chemotactic cytokines, which are involved in lymphocyte trafficking and migration of leucocytes to sites of injury, in immune surveillance and in healing process. They also play a role in pathogenesis of inflammatory diseases. Three novel CC chemokines were identified from domestic duck (Anas platyrhynchos) by screening of an enriched cDNA library constructed from mitogen-stimulated splenic mononuclear cells. Two of the clones (AB163 and AB330) had a very high nucleotide (both about 81%) and predicted amino acid level (71 and 76%, respectively) identity to the reported chicken macrophage inflammatory protein 1- (MIP-1; SCYA4) and regulated upon activation of normal T-cell expressed and secreted (RANTES; SCYA5) sequences. In phylogenetic analysis, these molecules clustered together with corresponding chemokines reported from other vertebrates. The third clone (AB187) had highest homology to chicken MIP-1 (36% amino acid identity) and showed closer relation to a number of chemokines belonging to monocyte chemoattractant proteins and MIP-1 chemokines. Expression of these molecules was upregulated upon mitogen stimulation of splenocytes as detected by semiquantitative RT-PCR. AB187 showed several fold increases (about 8.5 times) in the mRNA expression. Basal level expression of some of these chemokines was detected in both lymphoid and nonlymphoid tissues, including spleen, liver, lung, and bone marrow. Considering the importance of this animal species as a model for diseases such as chronic human hepatitis B, further studies will offer valuable insights into the role of these molecules in immunopathology of such diseases.The nucleotide sequences that are reported in this paper have been submitted to the NCBI Genbank database. Accession nos. AB163 (AY641435), AB187 (AY641436), and AB330 (AY641437).