虚拟细胞

虚拟细胞是20世纪末在国外刚刚兴起的一种细胞生物学研究方法,主要是通过计算机建立人工细胞模型,模拟细胞内外环境,从而进行生物学的研究和探索。虚拟细胞包含了多门学科前沿的研究成果,具有十分重要的意义。现从其发展历程、应用及其对生物学工作者的关系等方面进行综述。     

建立心脏功能研究的计算机模型

用计算机模拟建立生物学模型在现代生物学研究中是一种非常重要的方法.就心脏而言,从基因到细胞到整个器官,现在都建立了大量的计算机模型.这些模型在帮助我们证实心脏功能机制的假说、预测和评估药物的作用以及诊断疾病等方面都起着重要作用.就心脏不同层面的计算机模型进行了简要的综述.     

基于LabVIEW的虚拟呼吸机设计和人机系统模拟

机械通气在现代医学领域中有着重要的地位,而虚拟技术能够为医生制定机械通气治疗方案提供一定的帮助。人-机系统的模拟主要是对呼吸机气流源、气管(支气管)、肺等部分建立数学、电学模型,人体呼吸系统模拟仿真模型是以WEIBEL模型所提出的肺部、支气管与RC电路存在的对应关系为基础,达到在计算机上用Labview软件虚拟呼吸机前面板,并模拟人-机系统的工作过程的目的。     

体外皮肤检测模型的组织工程研究进展

皮肤刺激试验是临床前安全评价的常见项目,由于3R原则的发展,现逐渐采用体外皮肤检测模型来替代传统的动物实验。然而在国内皮肤模型的研究还处于起步阶段,种子细胞和支架材料是目前研究的主要内容。原代细胞和永生化细胞是皮肤刺激试验模型的种子细胞中较常用的两类。支架材料应用较广的是天然材料、合成材料和复合材料,而国外批量生产的模型中支架材料现阶段还是以天然材料为主。随着科技发展纳米技术也被利用来制备支架材料,使得皮肤模型的研究进入更深的领域。     

药物跨膜转运细胞模型影响因素及应用

本文详细介绍了Caco-2细胞系和MDCK细胞系的特点、跨膜转运细胞模型的建立及其影响因素,包括细胞模型的选择、细胞接种密度、细胞单层的紧密性等细胞因素和Transwell多微孔膜的性质等环境因素。概述了国内外关于利用Caco-2和MDCK细胞系作为模型进行药物筛选、药物相互作用和研究药物吸收转运机制等方面的内容及MDCK细胞模型作为肠道模型、肾脏模型及血脑屏障模型的应用。比较了Caco-2细胞和MDCK细胞在肠道模型方面的差别,MDCK细胞主要用于选择性研究药物在小肠吸收及转运机制,特别用于细胞旁被动转运药物的研究,而Caco-2细胞用于双向转运或能量依赖主动转运研究。MDCK细胞模型可在体外培养条件下平稳转染人类MDR1基因,因此可高表达P-gp基因,可作为可用于评估肾脏药物相互作用、快速进行候选药物筛选及研究药物转运机制的理想模型。     

基因组尺度集成细胞网络模型研究进展

细胞网络研究是系统生物学的一个研究热点,通过结合计算机模型和实验技术,从系统角度分析复杂的生物系统,可以为生物实验提供指导和预测。近十年来,国内外许多研究团队致力于基因组规模代谢网络、基因调控网络和信号转导网络模型的构建和分析,并取得了一定成果。而不同类型网络的集成和分析是当前生物网络研究中一个新的方向,并带来了诸多新的挑战。在本文中,主要对基因组尺度集成细胞网络模型的研究进展,特别是对代谢网络和转录网络的集成进行了详细论述,着重于集成网络的构建和分析方法,最后对该领域研究前景进行了展望。     

二维细胞运动模型的数值模拟

研究了一个二维细胞运动模型,该模型是个动边界问题．我们运用运动网格的有限元算法对此模型进行了数值模拟,数值结果表明,细胞最终收敛到固定形状,并且以固定速度向前运动．     

鸡胚细胞的微载体培养

国外有许多利用微载体培养各种贴壁细胞的报道。鸡胚细胞(CEF cells)是最早用于体外培养的细胞之一,用它可生产多种鸡的疫苗,如法氏囊、新城疫、马立克疫苗等。我国生产上多采用滚瓶法,近年来才有微载体法培养的探索。要进行细胞的大规模培养,转瓶是有效的模拟,可以模拟生物反应器培养的一些条件,为放大作准备。本文模拟生物反应器的培养条件,用500ml转瓶（装液200ml）研究了鸡胚细胞在徽栽体上巾壁和生长的规律,为放大培养作了准备。     

阿尔采末病的细胞模型及其在药理学研究中的应用

阿尔采末病（Alzheimer‘s disease,AD)是一种以进行性认知功能减退为主要临床症状的慢性中枢神经系统退行性疾病,为了研究AD的发病机制和寻找防治AD的药物,人们通过模拟AD脑中特征性病变,建立了许多相应的疾病模型,本文仅对细胞模型的研究现状做一综述。     

蛇毒与细胞凋亡

简要介绍了细胞凋亡的形态学变化和生物化学等特性,及其主要的定性、定量检测方法,综述了蛇毒在细胞凋亡和肿瘤研究中的发展概况和国外最新进展。     

Cellular automaton simulation examining progenitor hierarchy structure effects on mammary ductal carcinoma in situ

A computer simulation is used to model ductal carcinoma in situ, a form of non-invasive breast cancer. The simulation uses known histological morphology, cell types, and stochastic cell proliferation to evolve tumorous growth within a duct. The ductal simulation is based on a hybrid cellular automaton design using genetic rules to determine each cell's behavior. The genetic rules are a mutable abstraction that demonstrate genetic heterogeneity in a population. Our goal was to examine the role (if any) that recently discovered mammary stem cell hierarchies play in genetic heterogeneity, DCIS initiation and aggressiveness. Results show that simpler progenitor hierarchies result in greater genetic heterogeneity and evolve DCIS significantly faster. However, the more complex progenitor hierarchy structure was able to sustain the rapid reproduction of a cancer cell population for longer periods of time.     

BMP signaling and stem cell regulation

Stem cells play an essential role in cellular specialization and pattern formation during embryogenesis and in tissue regeneration in adults. This is mainly due to a stem cell's ability to replenish itself (self-renewal) and, at the same time, produce differentiated progeny. Realization of these special stem cell features has changed the prospective of the field. However, regulation of stem cell self-renewal and maintenance of its potentiality require a complicated regulatory network of both extracellular cues and intrinsic programs. Understanding how signaling regulates stem cell behavior will shed light on the molecular mechanisms underlying stem cell self-renewal. In this review, we focus on comparing the progress of recent research regarding the roles of the BMP signaling pathway in different stem cell systems, including embryonic stem cells, germline stem cells, hematopoietic stem cells, and intestinal stem cells. We hope this comparison, together with a brief look at other signaling pathways, will bring a more balanced view of BMP signaling in regulation of stem cell properties, and further point to a general principle that self-renewal of stem cells may require a combination of maintenance of proliferation potential, inhibition of apoptosis, and blocking of differentiation.     

Possible role of contact following in the generation of coherent motion of Dictyostelium cells

After aggregation by chemotaxis, cells of the cellular slime mold Dictyostelium discoideum form a multicellular structure and show coherent motion such as vortices. Here, we present a mathematical model to explain both aggregation and coherent motion of cells in two-dimensional space. The model incorporates chemotactic response of cells and the cell's property, called "contact following", to follow the other cells with which they are in contact. Analytical study and computer simulation using the model show that with contact following, cells form circular clusters within which cell rotation occurs. Unidirectional cell motion in a long belt of cells is another type of solution of the model. Besides, contact following has an effect to accelerate cell cluster merging. By considering the mechanism of cell movement, possible explanations of contact following are proposed.     

Quantification of cellular properties from external fields and resulting induced velocity: cellular hydrodynamic diameter.

An experimental technique is discussed in which the size distribution of a population of cells is determined by calculating each cell's settling velocity. The settling velocity is determined from microscopically obtained images which were recorded on SVHS tape. These images are then computer imaged and processed, and the cell's location and velocity are determined using a computer algorithm referred to as cell tracking velocimetry (CTV). Experimental data is presented comparing the distribution of human lymphocytes and a human breast cancer cell line, MCF-7, determined using a Coulter counter and the CTV approach.     

Primary mesenchyme cell-ring pattern formation in 2D-embryos of the sea urchin

Primary mesenchyme cell (PMC) migration during PMC-ring pattern formation was analyzed using computer-assisted time-lapse video microscopy in spread embryos (2D-embryo) of the sea urchin, Mespilia globulus , and a computer simulation. The PMC formed a near normal ring pattern in the 2D-embryos, which were shown to be an excellent model for the examination of cell behavior in vivo by time-lapse computer analysis. The average migration distance of the ventro-lateral PMC aggregate-forming cells (AFC) and that of the dorso-ventral PMC cable-forming cells (CFC) showed no significant difference. All PMC took a rather straightforward migration path to their destinations with little lag time after ingression. This in vivo cell behavior fitted well to a computer simulation with a non-diffusable chemotaxis factor in the cyber-cell migration field. This simulation suggests that PMC recognize their destination from a very early moment of cell migration from the vegetal plate, and implicates that a chemoattractive region is necessary for making the PMC migration pattern. The left- and right-lateral AFC and dorso and ventral CFC were each derived from an unequally divided one-quarter segment of the vegetal plate. This suggests that AFC and CFC have a distinctive ancestor in the vegetal plate, and the PMC are a heterogeneous population at least in terms of their destination in the PMC-ring pattern.     

木质部细胞分化的程序

本文主要对近十几年来有关木质部细胞分化研究中使用的实验系统及用这些系统所取得的重要进展作了评述.并以作者实验室的研究成果为基础,结合国内外研究进展,提出木质部细胞分化程序由参与细胞编程死亡(PCD)和次生壁构建的全部基因综合编制而成.以PCD过程各阶段的划分标准来看,木质部细胞分化中从IAA诱导形成层细胞平周分裂到细胞扩大前为PCD的起始阶段,其间包括死亡信号的发生、接受和传导,以及启始caspase(半胱氨酰基天门冬氨酸蛋白酶)类似物(例如caspase-8类似物)的活化;木质部母细胞的径向扩大为PCD的效应阶段,而效应caspase类似物(例如caspase-3类似物)活化DNase、DNA的片段化及次生细胞壁的构建和各种细胞器的解体则为PCD的清除降解阶段.至今还无法将DNase活化及其引起的DNA断裂过程与次生细胞壁构建过程分开.