Molecular Dynamics Simulation of the Crystallizable Fragment of IgG1—Insights for the Design of Fcabs

An interesting format in the development of therapeutic monoclonal antibodies uses the crystallizable fragment of IgG1 as starting scaffold. Engineering of its structural loops allows generation of an antigen binding site. However, this might impair the molecule’s conformational stability, which can be overcome by introducing stabilizing point mutations in the CH3 domains. These point mutations often affect the stability and unfolding behavior of both the CH2 and CH3 domains. In order to understand this cross-talk, molecular dynamics simulations of the domains of the Fc fragment of human IgG1 are reported. The structure of human IgG1-Fc obtained from X-ray crystallography is used as a starting point for simulations of the wild-type protein at two different pH values. The stabilizing effect of a single point mutation in the CH3 domain as well as the impact of the hinge region and the glycan tree structure connected to the CH2 domains is investigated. Regions of high local flexibility were identified as potential sites for engineering antigen binding sites. Obtained data are discussed with respect to the available X-ray structure of IgG1-Fc, directed evolution approaches that screen for stability and use of the scaffold IgG1-Fc in the design of antigen binding Fc proteins.     

蛋白质芯片微陈列条件优化及在疾病诊断上的应用

以PSA为模式抗体,对固定在氨基玻片表面时的甘油浓度、固定抗体的浓度、清洗缓冲溶液的选择等条件进行了优化。结果表明:含有30%(体积百分比)甘油的蛋白质溶液显示出灵敏度高、重现性好的微陈列点位;固定在氨基玻片表面的抗体的浓度较高时(2 mg.mL-1)可得荧光强度高的比较均匀的点位;依次用DI H2O、PBST、DI H2O洗涤氨基玻片表面时背景干扰少。按优化的蛋白质微陈列条件制备了芯片并尝试应用于对肿瘤标志物蛋白质PSA、AFP、CEA和CA15-3的检测。     

信息免疫系统规则的表示

讨论了免疫规则在信息免疫系统里的表示方式。提出层次编码方法,使用二进制串表示规则,既方便了规则的递归调用,又为后续亲和力的计算提供了方便。规则也具有很强的自学习功能和自适应能力,可实现规则的自我更新。     

Visual learning and classification of human epithelial type 2 cell images through spontaneous activity patterns

Identifying the presence of anti-nuclear antibody (ANA) in human epithelial type 2 (HEp-2) cells via the indirect immunofluorescence (IIF) protocol is commonly used to diagnose various connective tissue diseases in clinical pathology tests. As it is a labour and time intensive diagnostic process, several computer aided diagnostic (CAD) systems have been proposed. However, the existing CAD systems suffer from numerous shortcomings due to the selection of features, which is commonly based on expert experience. Such a choice of features may not work well when the CAD systems are retasked to another dataset. To address this, in our previous work, we proposed a novel approach that learns a set of filters from HEp-2 cell images. It is inspired by the receptive fields in the mammalian's vision system, since the receptive fields can be thought as a set of filters for similar shapes. We obtain robust filters for HEp-2 cell classification by employing the independent component analysis (ICA) framework. Although, this approach may be held back due to one particular problem; ICA learning requires a sufficiently large volume of training data which is not always available. In this paper, we demonstrate a biologically inspired solution to address this issue via the use of spontaneous activity patterns (SAP). The spontaneous activity patterns, which are related to the spontaneous neural activities initialised by the chemical release in the brain, are found as the typical stimuli for the visual cell development of newborn animals. In the classification system for HEp-2 cells, we propose to model SAP as a set of small image patches containing randomly positioned Gaussian spots. The SAP image patches are generated and mixed with the training images in order to learn filters via the ICA framework. The obtained filters are adopted to extract the set of responses from a HEp-2 cell image. We then employ regions from this set of responses and stack them into “cubic regions”, and apply a classification based on the correlation information of the features. We show that applying the additional SAP leads to a better classification performance on HEp-2 cell images compared to using only the existing patterns for training ICA filters. The improvement on classification is particularly significant when there are not enough specimen images available in the training set, as SAP adds more variations to the existing data that makes the learned ICA model more robust. We show that the proposed approach consistently outperforms three recently proposed CAD systems on two publicly available datasets: ICPR HEp-2 contest and SNPHEp-2.     

日本血吸虫抗体电化学免疫传感器研究

该文研制了一种高灵敏的基于辣根过氧化物酶(HRP)放大的电化学免疫传感器用于日本血吸虫抗体的检测.实验采用夹心法的模式,在电极表面固定了日本血吸虫抗原(SjAg),用以捕获血清中的日本血吸虫抗体(SjAb),然后再与辣根过氧化物酶(HRP)标记的羊抗兔IgG二抗形成免疫复合物.用计时安培法检测HRP酶催化H2O2还原对苯二酚底物产牛的电流,其大小与日本血吸虫抗体(SjAb)浓度在一定范围内成正比.对免疫反应的实验条件如电极表面固定抗原的浓度,HRP酶标二抗的浓度进行了优化.此外,还考察了其它蛋白质对测定结果的影响.结果表明,该方法操作简单,灵敏度高,线性范围宽,检测下限低.     

~（211）At标记单克隆抗体3H11及其Fab片段对裸鼠人胃癌移植瘤导向治疗的实验研究

用α放射性核素２１１Ａｔ标记的抗胃癌单克隆抗体３Ｈ１１和它的Ｆａｂ片段进行了荷人胃癌裸鼠的实验性治疗研究。经腹腔注射１４．８或２２．２ｋＢｑ／ｇ鼠的标记单抗，每５天一次，连续三次。治疗结果表明，此单抗对肿瘤有较强的抑制作用，治疗１５天后疗效最显著，抑制率分别达６５％和７２％。未发现各重要器官有明显的辐射损伤。     

^99mTc标记抗心肌肌凝蛋白单克隆抗体在实验性心肌梗塞中的研究

为比较＾９９ｍＴｃ－ＡＭＬＡ的特异性，将两组心肌梗塞２４ｈ大鼠分别注射＾９９ｍＴｃ－ＡＭＬＡ（ｎ＝２４）和＾９９ｍＴｃ－Ｎ－ＩｇＧ（ｎ＝１８），为研究不同心肌梗塞时间对摄取抗体的影响，将另一组不同心肌梗塞时间（２ｈ到１４ｄ共８个亚组）的大鼠注射＾９９ｍＴｃ－ＡＭＬＡ，计算三组的ＩＤ％／ｇ和梗塞心肌摄取／正常心肌摄取比（ＩＭ／ＮＭ）用一只心肌梗塞的狗注射＾９９ｍＴｃ－ＡＭＬＡ后离体心肌显像，结果表明     

人胰岛素酶联免疫分析法的建立

采用两株抗胰岛素单克隆抗体,一株包被聚苯乙烯板、另一株标记辣根过氧化物酶,建立了测定人胰岛素的双抗体夹心酶联免疫分析法。方法学研究表明,本方法的灵敏度为1.7mIU/L,曲线范围5~160mIU/L,批内、批间变异系数分别小于11%、15%,回收率96.4%~111.1%;高浓度胰岛素血清样品系列倍比稀释后测定,测定值与稀释度呈线性相关,相关系数0.998;38例健康人血清样品测定值为3.6~10.8mIU/L。该方法与人胰岛素放射免疫分析法测定结果的相关性良好,r=0.97。     

Whole-mount preparations of mouse lens epithelium for the fluorescent cytological study of actin

A technique is given for the preparation of a sheet of epithelial cells from the capsule of the crystalline lens. A new method is described for fixation and staining with fluorescent phalloidin or actin antibody in order to localize the actin cytoskeleton in this tissue. Optical section of the preparation resolves such actin features as apical polygonal arrays, sequestered actin bundles, perinuclear actin aggregates, observed here for the first time, and filamentous networks in the basal region of the cell. This method is superior to previous ones in its ability to preserve actin-abundant sectors distinctively.     

^99mTc直接标记单克隆抗体片段的改进方法

采用改进法将９９ｍＴＣ直接标记了ＭＣＡＢＣＬ３Ｆ（ａｂ’）２，在０．１ｍｏｌ／Ｌ、ｐＨ＝９．３的缓冲液中，标记率大于９５％．用荷ＬＳ１７４Ｔ瘤裸鼠作了显像和体内分布，在注射后１０ｈ可得清晰图像，该法可用于放射免疫显像。