Porcine Choroid plexus epithelial cells in culture: regulation of barrier properties and transport processes

The epithelial cells of the choroid plexus are the structural basis of the blood-cerebrospinal fluid (CSF)-barrier. Here we summarise our recent efforts to culture those cells mainly on permeable supports in vitro. Isolated from porcine brains, we report a simple protocol for the primary culture using cytosine arabinoside as an additive that is cytotoxic for other cells except the plexus epithelial cells. Enhanced barrier properties are obtained by withdrawal of serum from the culture medium after confluency is reached. Cells improve their polarity, permeability for hydrophilic substrates is lowered, electrical resistance is increased tenfold, and a pH-gradient is built up across the cell monolayer. Polarised secretion of proteins and most importantly fluid secretion into the apical filter compartment was attained and proven to be dependent on the Na(+),K(+)-ATPase activity. Active transport processes (penicillin G, riboflavin, myo-inositol, ascorbic acid) were studied and clearly showed the involvement of the organic anion transporter. The permeability of the barrier was found to be regulated by cyclic adenosine monophosphate (cAMP). Moreover, we report that cell proliferation and differentiation is controlled by components of the extracellular matrix. The present culture model could now be used as an in vitro system to quantify drug transport across the blood-CSF-barrier.     

Electron diffraction analysis and techniques for studying polypeptides and other polymers

A review of electron diffraction studies of polypeptide structures is given together with a discussion of the methods for obtaining diffraction patterns without serious specimen damage by electrons. Electron diffraction studies of poly-β-benzyl-L-aspartate show that diffraction intensities can be used quantitatively to determine polypeptide structures and the advantages of these studies in observing high angle meridional reflections are shown up by the observation of a novel structure in the unheated left handed helical form of the polypeptide. A large catalogue of techniques for preparing orientated films of polypeptides suitable for electron diffraction investigations makes the technique a powerful one for studying these structures. Polypeptides are shown to be useful for studying electron beam damage in protein-like materials.     

Function to structure/material mappings for conceptual design synthesis and their supportive strategies

Conceptual design aims at developing design concepts that can satisfy the specified design requirements, where the design concepts are normally in the form of a physical structure. There has been quite a lot of work done in this area of design research, from which it is now generally agreed that functional decomposition and function to structure mapping are two fundamental steps of design task in synthesis for design solution. However, there have not been many strategies to support these design tasks, especially for the function to structure mapping. In addition, design solutions may not just consist of physical structure. Sometimes only materials can provide a feasible design solution; sometimes a materials solution might be more effective and/or more economic than a structural solution. Again, there have not been many strategies that explicitly considered materials solution at the early design stage. To address these problems, this paper proposes three mappings from function to both structure and material. Several embodiment strategies supporting these mappings are also proposed, including four functional matches used for identifying functional design solutions, and a performance match used for ensuring that the identified solution can satisfy the performance requirements or constraints. A design case is also studied to illustrate as well as to test the effectiveness of these strategies.     

基于视觉的采摘机器人目标识别与定位方法研究综述

目标识别和定位的精度直接关系到采摘机器人采摘效率、质量和速度。本文对近年来采摘机器人的目标识别和三维定位的研究工作进行了系统性的总结和分析,综述了果蔬识别和定位的几种主要方法:目标识别:数字图像处理技术、基于机器学习的图像分割与分类器和基于深度学习的算法;三维定位:基于单目彩色相机、基于立体视觉匹配、基于深度相机、基于激光测距仪和基于光基3D相机飞行时间的三维定位。分析了影响果蔬识别和定位精度的主要因素:光照变化、复杂的自然环境、遮挡以及动态环境干扰下成像不精确。最后对采摘机器人目标识别与定位的未来发展作了几点展望。     

Toxicology of choroid plexus: special reference to metal-induced neurotoxicities

The chemical stability in the brain underlies normal human thinking, learning, and behavior. Compelling evidence demonstrates a definite capacity of the choroid plexus in sequestering toxic heavy metal and metalloid ions. As the integrity of blood-brain and blood-CSF barriers, both structurally and functionally, is essential to brain chemical stability, the role of the choroid plexus in metal-induced neurotoxicities has become an important, yet under-investigated research area in neurotoxicology. Metals acting on the choroid plexus can be categorized into three major groups. A general choroid plexus toxicant can directly damage the choroid plexus structure such as mercury and cadmium. A selective choroid plexus toxicant may impair specific plexus regulatory pathways that are critical to brain development and function, rather than induce massive pathological alteration. The typical examples in this category include lead-induced alteration in transthyretin production and secretion as well as manganese interaction with iron in the choroid plexus. Furthermore, a sequestered choroid plexus toxicant, such as iron, silver, or gold, may be sequestered by the choroid plexus as an essential CNS defense mechanism. Our current knowledge on the toxicological aspect of choroid plexus research is still incomplete. Thus, the future research needs have been suggested to focus on the role of choroid plexus in early CNS development as affected by metal sequestration in this tissue, to explore how metal accumulation alters the capacity of the choroid plexus in regulation of certain essential elements involved in the etiology of neurodegenerative diseases, and to better understand the blood-CSF barrier as a defense mechanism in overall CNS function.     

Facile green synthesis approach for the production of chromium oxide nanoparticles and their different in vitro biological activities

Green synthesis of nanoparticles using plants has become a promising substitute for the conventional chemical synthesis methods. In the present study, our aim was to synthesize chromium oxide nanoparticles (Cr₂O₃NPs) through a facile, low‐cost, eco‐friendly route using leaf extract of Rhamnus virgata (RV). The formation of Cr₂O₃NPs was confirmed and characterized by spectroscopic profile of UV–Vis, EDX, FTIR, and XRD analyses. The UV‐visible spectroscopy has confirmed the formation of Cr₂O₃NPs by the change of color owing to surface plasmon resonance. The bioactive functional groups present in the leaf extract of RV involved in reduction and stabilization of Cr₂O₃NPs were determined by FTIR analysis. Based on XRD analysis, crystalline nature of Cr₂O₃NPs was determined. The morphological shape and elemental composition of Cr₂O₃NPs were investigated using SEM and EDX analyses, respectively. With growing applications of Cr₂O₃NPs in biological perspectives, Cr₂O₃NPs were evaluated for diverse biopotentials. Cr₂O₃NPs were further investigated for its cytotoxicity potentials against HepG2 and HUH‐7 cancer cell lines (IC₅₀: 39.66 and 45.87 μg/ml), respectively. Cytotoxicity potential of Cr₂O₃NPs was confirmed against promastigotes (IC₅₀: 33.24 μg/ml) and amastigotes (IC₅₀: 44.31 μg/ml) using Leishmania tropica (KMH₂₃). The Cr₂O₃NPs were further evaluated for antioxidants, biostatic, alpha‐amylase, and protein kinase inhibition properties. Biocompatibility assay was investigated against human macrophages which confirmed the nontoxic nature of Cr₂O₃NPs. Overall, the synthesized Cr₂O₃NPs are biocompatible and nontoxic and proved to possess significant biopotentials. In future, different in vivo studies are needed to fully investigate the cytotoxicity and mechanism of action associated with these Cr₂O₃NPs.     

Actin machinery of phagocytic cells: universal target for bacterial attack

Uptake of microorganisms by eukaryotic cells depends on proper functioning of the actin machinery. It creates a driving force for the cell membrane deformations necessary for ingestion and killing of microbes by phagocytes. Therefore, specific alterations in the activity of the actin apparatus could be favorable for pathogenic bacteria, representing an efficient mechanism in their virulence. Such alterations are supposed to be achieved in two principle ways. One is accomplished via binding of bacterial ligands to certain surface receptors, which initiate subsequent actin cytoskeleton rearrangements. Another is to introduce cytoskeleton-targeted products directly into eukaryotic cells and in this way modulate the activity of the actin apparatus. Indeed, Legionella and some other intracellular parasites possess ligands able to stimulate certain receptors on the surface of phagocytes and possess devices suitable for translocation of effector molecules into eukaryotic cytoplasm. The results of such events could be increased uptake of these microbes and their subsequent transportation to permit multiplication in their intracellular niche. On the contrary, representatives of Clostridium and a number of other extracellular pathogens create products which penetrate eukaryotic cells and disorganize the actin cytoskeleton network, thus making uptake of these pathogens by phagocytes impossible.     

一种运动目标检测与跟踪的方法研究

针对视频序列中运动目标的检测与跟踪进行了研究,提出了一种基于视频序列的YCbCr模式归一化定义,利用三帧图像差分,区域生长生成运动矩形框的方法对目标进行运动分割;并利用基于速度差的粒子滤波器对运动框的移动进行预测,从而达到快速跟踪运动目标的目的。实验结果表明通过调节内部参数,在固定摄像机不复杂背景下对人、车运动目标检测与跟踪是快速且有效的。     

激光聚变靶丸球度测量与评定

为了解决激光聚变靶丸表面形貌高精度测量与评定的难题,提出一种激光差动共焦靶丸球度测量与评定方法,该方法利用激光差动共焦测量系统的轴向响应曲线的过零点与其物镜焦点位置相对应这一特性实现对靶丸表面的定焦,通过将靶丸在两个正交的方向上分别旋转,测量并获取靶丸表面的数个截面,实现靶丸表面全形貌测量,利用最小区域球度评定算法,建立靶丸球度评定的三维模型,对靶丸表面形貌进行定量评定。搭建实验装置对靶丸表面进行采样测量,评定结果显示,该方法的测量重复性为0.15μm,为靶丸表面形貌测量与评定提供了一种可行方案。     

Controller synthesis for automatic control systems: State and prospects

This paper considers the state and prospects for studies of the central problem of the theory and practice of automatic control—the problem of controller synthesis for systems with nonlinear plants. A crucial factor in the performance of controllers for nonlinear plants is the use of deep feedback for derivatives of the output variable, which provides localization of disturbances in fast subprocesses (against the background of the main processes) and allows the generation of the required dynamic properties     

BATTY83: A computer program for thick target PIXE analysis

Improvements to the computer program BATTY are described. The program is now largely automatic, requiring only a list of elements to be fitted. Features that are discussed with their effect on spectrum fitting include automatic determination of the background, corrections to relative line intensities due to self absorption and escape and sum peaks. Some changes were made to the model describing the non Gaussian portion of an X-ray peak spectrum.     

Femtosecond laser cutting of human corneas for the subbasal nerve plexus evaluation

Assessment of various morphological parameters of the corneal subbasal nerve plexus is a valuable method of documenting the structural and presumably functional integrity of the corneal innervation in health and disease. The aim of this work is to establish a rapid, reliable and reproducible method for visualization of the human corneal SBP using femtosecond laser cut corneal tissue sections. Trephined healthy corneal buttons were fixed and processed using TissueSurgeon—a femtosecond laser based microtome, to obtain thick tissue sections of the corneal epithelium and anterior stroma cut parallel to the ocular surface within approximately 15 min. A near infrared femtosecond laser was focused on to the cornea approximately 70–90 μm from the anterior surface to induce material separation using TissueSurgeon. The obtained corneal sections were stained following standard immunohistochemical procedures with anti‐neuronal β‐III tubulin antibody for visualization of the corneal nerves. Sections that contained the epithelium and approximately 20–30 μm of anterior stroma yielded excellent visualisation of the SBP with minimal optical interference from underlying stromal nerves. In conclusion, the results of this study have demonstrated that femtosecond laser cutting of the human cornea offers greater speed, ease and reliability than standard tissue preparation methods for obtaining high quality thick sections of the anterior cornea cut parallel to the ocular surface.     

偏振场景目标探测的建模与仿真

针对用光学遥感技术探测复杂场景下的目标时,真实环境下的目标、背景反射以及大气气溶胶辐射之间具有相当大的互干扰性,本文研究了偏振场景目标的建模与仿真技术。介绍了偏振场景仿真的光学理论与偏振模型基础,对Priest-Germer模型进行了数值仿真与分析。基于Priest-Germer模型,开发了偏振视景目标探测仿真软件,给出仿真软件的设计思想和软件框架。介绍了偏振双向分布反射函数模型,给出其偏振形式的Stokes表达式并进行数值仿真分析。给出了两种目标模型分别赋予两种不同表面材质时在440nm和600nm波长辐照条件下的4组偏振仿真实验及偏振图像的灰度直方图,并进行比较和分析,结果表明:基于Priest-Germer模型的偏振仿真软件对目标、辐照波长、材质具有较高的敏感性,能够提供较好的分辨和识别能力。     

Structure and expression of the transthyretin gene in the choroid plexus: a model for the study of the mechanism of evolution

Thyroid hormones are key regulators of brain differentiation and function. They permeate strongly into lipid membranes. However, a substantial portion of thyroid hormone is retained in the intravascular/extracellular compartments by binding to plasma proteins. In the brain, transthyretin is the most important of these proteins. This transthyretin is synthesized in the epithelial cells of the choroid plexus and exclusively secreted towards the brain. A net movement of thyroid hormones from the blood to the brain ensues. During evolution, transthyretin synthesis in the choroid plexus and the beginnings of a neocortex first appeared at the stage of the stem reptiles. The affinity of transthyretin for thyroxine increased and that for triiodothyronine decreased during evolution. This could augment the importance of deiodination for regulation of metabolism and gene expression by thyroid hormones in the brain. Successive shifts of the splice site at the 5' end of exon 2 of transthyretin precursor mRNA in the 3' direction led to a shortening of the N-terminal sections and to an increase in hydrophilicity of the N-terminal regions of transthyretin. This shift can be explained by a sequence of single base mutations. It could be an example for a molecular mechanism of positive Darwinian evolution. The selection pressure, which led to the expression of the transthyretin gene in the choroid plexus during evolution, might have been the maintenance of thyroid hormone homeostasis in the extracellular compartment of the brain in the presence of the greatly increasing volume of the lipid phase.     

Distribution of nestin protein: immunohistochemical study in enteric plexus of rat duodenum

The intermediate nestin filament is expressed in neural stem cells, neuroectodermal tumors and various adult tissues under situations that reproduce developmental phases, e.g., physiological renewal of certain cell types, tissue regeneration, and healing or revascularization. In the human gastrointestinal tract, nestin has been reported in glial cells and interstitial cells of Cajal. We examined by immunohistochemistry the appearance and distribution of nestin protein in enteric ganglia of rat duodenum. Through the myenteric and submucosal plexuses, a high number of nestin-positive cells were visualized in this specie. The nestin-positive cells were smaller and more numerous than enteric neurons. They were present both within and around ganglia. The results of this study suggest that the rat enteric glial cells (EGCs) are rich in nestin, a protein usually associated with dividing or migrating cells and the dynamic reorganization of nestin filaments during the cell cycle. EGCs could function as enteric stem cells.     

基于目标成本法的模块化产品变型设计研究

将成本设计理念应用于模块化产品变型设计进行了研究,建立了产品模块化变型设计的目标成本控制模型和流程,实现了产品模块化变型设计过程中功能满足,冗余成本降低的要求,提高了模块化产品的设计效率以及加快了产品的上市时间.     

光电跟踪仪目标仿真系统设计

舰载光电跟踪仪需全天候工作,具有信息量大、可视性强、分辨率高等特点,是舰船情报系统的重要组成部分。设计了一种针对舰船和空中目标进行光电跟踪的仿真系统,介绍了该系统的组成和仿真软件的功能模块,通过对该系统的静态和动态目标跟踪能力分析与测试,证实该系统可以对舰载光电跟踪仪跟踪能力进行全面的测试。     

变维卡尔曼滤波实现运动目标的跟踪

在球坐标激光跟踪测量系统中，由于受到各种干扰的影响，激光跟踪系统测量所得到的目标状态参量的测量值与目标的真实状态往往不尽相同，如何抑制随机误差，成为提高激光跟踪测量系统精度的一个重要问题。本文提出变维卡尔曼滤波算法来抑制随机误差的影响，仿真结果验证了该方法的有效性。