鲍氏针层孔菌菌丝体多糖脱蛋白方法研究

目的:对多糖提取液中的蛋白质去除方法和条件进行了优化,比较不同方法对蛋白质去除的影响。方法:采用Sevag法与三氯乙酸(TCA)法去除鲍氏针层孔菌多糖中的游离蛋白质。结果:TCA去除蛋白质的效果优于Sevag法,TCA最佳脱蛋白条件为:5%三氯乙酸用量,处理3次,反应时间30min;在此条件下,蛋白质去除率为82%,多糖损失率为10.8%。结论:TCA法为最佳的鲍氏针层孔菌脱蛋白方法。     

一种基于稀疏分解去除EEG信号中MRI伪迹的新方法

在脑电图(Electroencephalography,EEG)和功能磁共振成像(Functional magnetic resonance imaging, FMRI)同时记录时,如何有效的去除混入EEG信号中的强磁共振(Magnetic resonance imaging,MRI)伪迹干扰信号是当前在EEG和FMRI的联合研究中面临的一个信号前期处理难点。主要从MRI干扰信号和EEG信号在时空上的差别出发,提出了一种基于混合过完备库的稀疏成分分析的分解方法,实现了强MRI干扰下的EEG信号的估计。在方法实现中,首先利用小波和离散余弦构造能体现MRI干扰和EEG时空特性差别的混合过完备库,然后通过匹配追踪(Matching pursuit,MP)方法在混合过完备库中的学习,实现MRI伪迹的消除。对模拟数据以及真实记录的混入了MRI干扰的EEG信号的估计实验结果,证实了该方法的有效性。     

基于XML技术的电子病历管理平台研究与实现

介绍电子病历的内涵与发展历程,阐述基于XML技术电子病历管理平台构建的意义、功能及实现方案,从基于XML的电子病历建模,支持HL7、DICOM和XML集成医疗网关,基于SOA、多标准兼容集成网关的系统架构几方面介绍平台的具体实现技术。     

Deep weakly-supervised breast tumor segmentation in ultrasound images with explicit anatomical constraints

Breast tumor segmentation is an important step in the diagnostic procedure of physicians and computer-aided diagnosis systems. We propose a two-step deep learning framework for breast tumor segmentation in breast ultrasound (BUS) images which requires only a few manual labels. The first step is breast anatomy decomposition handled by a semi-supervised semantic segmentation technique. The input BUS image is decomposed into four breast anatomical structures, namely fat, mammary gland, muscle and thorax layers. Fat and mammary gland layers are used as constrained region to reduce the search space for breast tumor segmentation. The second step is breast tumor segmentation performed in a weakly-supervised learning scenario where only image-level labels are available. Breast tumors are first recognized by a classification network and then segmented by the proposed class activation mapping and deep level set (CAM-DLS) method. For breast anatomy decomposition, the proposed framework achieves Dice similarity coefficient (DSC) of 83.0 ± 11.8%, 84.3 ± 10.0%, 80.7 ± 15.4% and 91.0 ± 11.4% for fat, mammary gland, muscle and thorax layers, respectively. For breast tumor recognition, the proposed framework achieves sensitivity of 95.8%, precision of 92.4%, specificity of 93.9%, accuracy of 94.8% and F1-score of 0.941. For breast tumor segmentation, the proposed framework achieves DSC of 77.3% and intersection-over-union (IoU) of 66.0%. In conclusion, the proposed framework could efficiently perform breast tumor recognition and segmentation simultaneously in a weakly-supervised setting with anatomical constraints.     

心肌力学量化评价技术现状及研究进展

心脏的心肌组织体积占心脏总体积的95%以上。毫无疑问,任何心脏疾病的发生和发展均将对心肌组织产生不同程度的损伤。而组织结构的损伤必将导致心肌力学功能的异常。如何早期检出并全面描述心肌的结构功能损伤是临床早期发现和诊断心肌病变的关键。本文就现有的心肌力学影像学评价技术的研究现状及研究方向作一述评。     

From the Cover: PNAS Plus: The CentO satellite confers translational and rotational phasing on cenH3 nucleosomes in rice centromeres

Plant and animal centromeres comprise megabases of highly repeated satellite sequences, yet centromere function can be specified epigenetically on single-copy DNA by the presence of nucleosomes containing a centromere-specific variant of histone H3 (cenH3). We determined the positions of cenH3 nucleosomes in rice (Oryza sativa), which has centromeres composed of both the 155-bp CentO satellite repeat and single-copy non-CentO sequences. We find that cenH3 nucleosomes protect 90–100 bp of DNA from micrococcal nuclease digestion, sufficient for only a single wrap of DNA around the cenH3 nucleosome core. cenH3 nucleosomes are translationally phased with 155-bp periodicity on CentO repeats, but not on non-CentO sequences. CentO repeats have an ∼10-bp periodicity in WW dinucleotides and in micrococcal nuclease cleavage, providing evidence for rotational phasing of cenH3 nucleosomes on CentO and suggesting that satellites evolve for translational and rotational stabilization of centromeric nucleosomes.Centromeres, the chromosomal domains that attach to spindle microtubules to segregate eukaryotic chromosomes in mitosis and meiosis, are DNA elements bound by special nucleosomes that contain a centromere-specific variant of histone H3 (cenH3). In most plants and animals, cenH3 nucleosomes are found on centromeric DNA that comprises megabases of tandemly repeated “satellite” sequences. Despite this apparent preference for repetitive DNA, a fully functional centromere, called a neocentromere, can occasionally form by assembling cenH3 nucleosomes on a single-copy DNA sequence that was not previously part of a centromere, indicating that centromere specification is epigenetic in plants and animals (for reviews, see refs. 1–4).The tandem arrays of highly repeated satellite sequences that compose most plant and animal centromeres can differ dramatically between closely related species (5), and even between different chromosomes (6–8), suggesting that satellite arrays undergo rapid evolution through expansions, contractions, gene conversions, and transpositions. Monomers of satellite repeats range in length from 5 bp in Drosophila to 1,419 bp in cattle although more than half of described monomers in 282 species have lengths between 100 and 200 bp, often regarded as approximately the length of nucleosomal DNA (6, 9). The cenH3 nucleosomes typically occupy only a portion of the satellite repeats, often in discontinuous blocks (7, 10–12), and the same or similar repeats often underlie flanking pericentromeric heterochromatin composed of conventional nucleosomes. Some of these repeats, for example African green monkey α-satellite DNA, have long been known to position conventional nucleosomes, resulting in arrays of regularly spaced nucleosomes, said to be translationally phased (13–15). Nucleosomes can occupy multiple alternative translational phases on the same satellite (16, 17). Translationally phased nucleosomal arrays have also been observed on satellites in cucumber and in several cereal species, where phasing varies among repeats and chromosomal regions (18, 19).Recently deep-sequencing technology has been applied to centromeres treated with micrococcal nuclease (MNase), which preferentially digests linker DNA between nucleosomes, to determine the positioning of cenH3 nucleosomes on satellite repeats. In human cultured cells, substantial translational phasing of CENP-A, the human cenH3, was reported on α-satellite (20). In maize, a similar approach mapped CENH3 (the name used for plant cenH3s) on the 156-bp maize centromeric satellite CentC and on two retrotransposon-derived centromeric sequences, CRM1 and CRM2 (21). Evidence for translational phasing of CENH3 on CentC and CRM1 was lacking, but 190-bp phasing was observed on CRM2. CentC was shown to have a strong periodicity of AA or TT dinucleotides about every 10 bp, which corresponds to one turn of the DNA double helix. This periodicity is thought to favor a particular orientation of the DNA toward the nucleosome core particle, based on DNA bendability, and is known as rotational phasing of nucleosomes (22–24).Rice has centromeres characterized by the 155-bp satellite sequence CentO, which is related to maize CentC (25, 26). Although some rice centromeres have megabases of CentO satellites, other evolutionarily new centromeres have little CentO, so CENH3 nucleosomes are found on both CentO and non-CentO sequences (12). For example, Cen8 is comprised of mostly non-CentO sequences and has a CentO array (CentO_8) that is spanned by a sequenced BAC (27). Centromeres like Cen8 are thought to represent an intermediate stage in centromere evolution between rare neocentromeres that form on unique sequences and mature centromeres populated by megabase-sized arrays of satellites (7, 12). Cen8 therefore presents an opportunity to compare the organization of CENH3 nucleosomes on CentO and non-CentO sequences. To that end, we used an antibody to rice CENH3 (27) to perform chromatin immunoprecipitation (ChIP) of CENH3 nucleosomes digested with MNase and sequenced the bound DNA (ChIP-Seq) to determine the positions of CENH3 nucleosomes on rice centromeres. We analyzed the sizes and positions of CENH3 nucleosomal DNA fragments on both CentO and non-CentO sequences to address the role of satellites in organizing centromeric chromatin and analyzed the sequence features of these fragments to look for evidence of nucleosome positioning signals.     

亲密伴侣暴力评估工具的研究进展

亲密伴侣暴力(IPV)是指亲密伴侣之间发生的威胁或虐待行为,其具体形式包括身体、精神或性伤害。现有研究表明,IPV可给受害者带来一系列身体和心理上的损伤,严重影响受害者的生活质量。准确评估IPV是制定针对性预防措施的前提和基础。然而,国内对IPV的研究尚处于起步阶段,针对IPV的评估工具缺乏。本文将国外常用的8种IPV评估工具分为研究工具和筛查工具,对各工具的主要内容、应用情况及特点进行综述,并对这8种评估工具的优缺点进行比较,旨在为我国IPV相关研究提供借鉴,为准确评估和识别IPV受害者提供依据。