家兔急性前脑缺血再灌流损伤的实验研究

为探讨不同时间急性脑缺血再灌流后脑损伤的恢复情况,本实验在20只家兔以结扎双侧椎动脉及夹闭双侧颈总动脉造成急性前脑缺血,观测于不同时间缺血后开放双侧颈总动脉夹进行再灌流2小时后的脑组织损伤特     

大鼠脑缺血模型的复制方法及评价

脑血管疾病是危害人类健康最严重的疾病之一 ,亦是临床及基础医学工作者的研究重点。由于临床研究的局限性 ,动物实验就成为研究脑血管疾病的重要途径。但是 ,动物实验要求有一个接近于人类脑缺血性疾病的动物模型 ,而疾病的动物模型往往与人类的自发疾病差别较大 ,因此 ,缺血性脑中风模型的研究仍然是非常重要的课题。1　脑缺血模型的复制方法1 .1　颈外血管阻断法1 .1 .1　双侧颈总动脉夹闭方法 :分离颈总动脉 ,结扎或用动脉夹夹闭。优点 :操作简便。缺点 :由于存在着双侧椎动脉的代偿 ,脑缺血较轻 ,部位不宜确定。有人报道脑血流量下降不…     

体温对小鼠脑缺血再灌学习记忆障碍模型的影响

小鼠反复脑缺血再灌引起学习记忆障碍模型已有报导，我们以水迷路实验成绩为评价指标，并测定脑内乳酸水平检测其代谢情况，评价了温度对此模型的影响。实验用昆明雄性小鼠２５～２８ｇ，水合氯醛麻醉下颈正中切口分离双侧颈总动脉，并用无损动脉夹夹闭动脉。缺血方式采用...     

虾青素提高血管性痴呆小鼠学习记忆能力

目的 探讨腹腔给药虾青素对于血管性痴呆(VaD)小鼠学习记忆能力的影响及其作用机制.方法 采用双侧颈总动脉夹闭法建立小鼠VaD模型后随机分成假手术组、模型组、虾青素低剂量组及虾青素高剂量组,分别给予相应形式的药物治疗.Morris水迷宫观察各组小鼠的学习记忆及空间探索能力,尼氏染色、免疫组织化学染色、Western b...     

夹闭大鼠双侧颈总动脉对胃运动的影响

采用动脉夹夹闭大鼠双侧颈总动脉,胃内放置水囊记录胃运动的方法,观察了脑供血不足对胃运动的影响。结果表明:(1)夹闭30 min过程中,最初2 min内的胃运动指标(收缩频率、总收缩时程、总收缩幅度、胃运动指数)较夹闭前2 min内抑制显著;夹闭第28~30 min(即松开动脉夹前2 min内)的胃运动各项指标较夹闭前2 min均无显著差异。(2)松开动脉夹30 min过程中,松开后最初2 min内与松开前2 min内相比,胃运动抑制显著;但松开后第28~30 min的胃运动与松开前2 min内的胃运动相比,无显著差异。这些结果说明:夹闭双侧颈总动脉造成脑局部供血不足初期,对胃运动有抑制作用,但随着结扎时间的延长,这种抑制作用逐渐消除,可能是椎-基底动脉环起了代偿作用。     

孕酮对前脑缺血沙土鼠海马受损神经元的保护作用及其机制

本实验应用免疫细胞化学技术、HE染色和Nissl染色方法观察孕酮对前脑缺血沙土鼠海马受损神经元的保护作用及其机制。本研究选用24只成年、健康、雄性沙土鼠,随机分为三组:脑缺血组,沙土鼠被麻醉后,颈部正中切口,分离双侧颈总动脉,用动脉夹同时夹闭双侧颈总动脉,阻断血流20min后去除动脉夹恢复血流,缝合颈部切口,制成沙土鼠前脑缺血再灌动物模型;假手术组动物除不阻断血流外,其它步骤同动物模型的制备;孕酮实验组则在前脑缺血后腹腔注射孕酮(40mg/kg)。结果如下:1HE染色和Nissl染色,前脑缺血20min后沙土鼠背侧海马CA1区锥体细胞数目明显…     

葛根素抑制脑缺血再灌注损伤的大鼠海马CA1区锥体细胞L-型钙通道

近年来,对葛根素(puerarin)在脑缺血再灌注损伤中的保护作用研究的较多,但多是通过酶学或形态学及免疫组化等方法获得的[1],尚未见用膜片钳技术研究其保护机制的报道。本研究用该技术从离子通道角度来揭示葛根素防治大鼠缺血再灌注脑损伤的可能机制。1材料与方法1.1动物造模和分组:SD大鼠(广州中医药大学实验动物中心),雌雄不限,体重200~250g/只,清洁级。采用改良Pulsinelli四血管闭塞法制作大鼠全脑缺血模型。造模24h后用无损伤微动脉夹夹闭双侧颈总动脉,15min后撤去双侧动脉夹,恢复脑血流,此为再灌流期。大鼠随机分为(1)正常组;(2)模型…     

夹闭大鼠双侧颈总动脉对胃酸分泌的影响

用动脉夹夹闭麻醉大鼠双侧颈总动脉致脑供血不足,观察了脑供血不足后胃酸分泌量的变化。经食道插管向胃内输入生理盐水(37℃,pH=7.0),由幽门插管收集灌流液,每15min收集1个样品,用5mmol/LNaOH滴定灌流液中的H 分泌量。比较夹闭双侧颈总动脉前45min、夹闭45min期间以及恢复脑供血45min胃酸分泌量的变化。结果表明:夹闭双侧颈总动脉期间胃酸分泌量显著增多(由夹闭前的6.06μmol/15min,增加到夹闭期间的7.59μmol/15min,P<0.01);恢复供血后与夹闭前相比胃酸分泌量无显著变化(夹闭前6.06μmol/15min,恢复供血后5.67μmol/15min,P>0.05)。这些结果说明:夹闭双侧颈总动脉造成脑供血不足可增加胃酸的分泌。     

C57black/6小鼠全脑缺血模型脑内Bax和Bcl-2的表达

本研究采用C57black/6小鼠制备全脑缺血模型,观察脑缺血后多个脑区Bax和Bcl-2基因的表达。双侧颈总动脉夹闭(bilateral common carotid artery occlusion,BCCAO)15min,造成全脑缺血,24h后取脑组织进行Bax和Bcl-2免疫组织化学染色。结果显示:Bax阳性细胞广泛分布在大脑皮层、丘脑和杏仁核,阳性产物主要位于胞质内。除丘脑外,其他各部位Bax阳性神经元的密度缺血组均显著高于假手术组(P<0.05);缺血组各区域细胞染色灰度值均显著低于假手术组(P<0.01)。Bcl-2阳性细胞在大脑皮层和丘脑均有表达,缺血组大脑皮层内Bcl-2阳性神经元的密度显著高于假手术组(P<0.05);缺血组各区域细胞染色灰度值均显著低于假手术组(P<0.01)。以上结果表明双侧颈总动脉夹闭法致C57black/6小鼠全脑缺血模型可致多脑区Bax和Bcl-2的广泛表达,提示Bax和Bcl-2可能介导了缺血所致的神经元损伤。     

淫羊藿甙对脑缺血再灌损伤小鼠的保护作用

目的：探讨淫羊覆甙对脑缺血再灌损伤小鼠的保护作用及其机制。方法：采用双侧颈总动脉夹闭合并取血降压再灌注的方法建立小鼠脑缺血再灌损伤模型，随机分为假手术组、模型组、淫羊藿甙防治组，检测各组行为学、总抗氧化能力、超氧化物歧化酶(superoxide dismutase，SOD)、丙二醛(malondialdehyde,MDA)、ATPase酶活性的变化。结果：(1)模型组小鼠学习记忆能力减退．淫羊藿甙(10、30、100mg／kg)灌胃可不同程度的提高小鼠学习记忆成绩。     

Using models of nucleotide evolution to build phylogenetic trees

Molecular phylogenetics and its applications are popular and useful tools for making comparative investigations in genetics; however, estimating phylogenetic trees is not always straightforward. Some phylogenetic estimators use an explicit model of nucleotide evolution to estimate evolutionary parameters such as branch lengths and tree topology. There are many models to choose from, and use of the optimal model for a particular data set is important to avoid a loss of power and accuracy in phylogenetic estimations. Here, we review some molecular evolutionary forces and the parameters included in some common models of evolution used to interpret resulting patterns of molecular variation. We present some statistical methods of selecting a particular model of nucleotide evolution, and provide an empirical example of model selection. Statistical model selection strikes a balance between the bias introduced by some models and the increased variance of parameter estimates that results from using other models.     

医学心理学研究中实验动物模型及应用概述

目的 为认识和应用心理学实验动物模型提供一定的参考。方法 介绍了在医学心理学研究中常用的实验动物模型及其应用。主要包括有焦虑动物模型、抑郁动物模型、创伤后应激障碍(PTSD)模型、大鼠吗啡成瘾及戒断模型、睡眠剥夺动物模型及社会应激动物模型等。结果 了解医学心理学研究中的动物模型制作和使用方法。结论 应用实验动物模型将会使医学心理学的研究得到进一步的发展。     

Naming game on adaptive weighted networks

We examine a naming game on an adaptive weighted network. A weight of connection for a given pair of agents depends on their communication success rate and determines the probability with which the agents communicate. In some cases, depending on the parameters of the model, the preference toward successfully communicating agents is essentially negligible and the model behaves similarly to the naming game on a complete graph. In particular, it quickly reaches a single-language state, albeit some details of the dynamics are different from the complete-graph version. In some other cases, the preference toward successfully communicating agents becomes much more important and the model gets trapped in a multi-language regime. In this case gradual coarsening and extinction of languages lead to the emergence of a dominant language, albeit with some other languages still present. A comparison of distribution of languages in our model and in the human population is discussed.     

基于小鼠肥大细胞瘤P815模型的肿瘤免疫学研究进展

肿瘤动物模型是研究肿瘤免疫学、临床前期评价肿瘤治疗方案有效性和安全性的重要前提.P815肿瘤模型是一种较为成熟的小鼠肿瘤研究模型,因其具有某些独特的优点而被研究者广泛采用.近年来,在已鉴定出P815AB、P815E等肿瘤抗原的基础上,基于该模型的肿瘤疫苗及相关肿瘤免疫学研究都有了相当大的进展.     

论医学模式的变革与医学仪器未来走势

19世纪末20世纪初执照行医制度的出现和现代医学仪器的诞生，促使医疗与保健从以家庭为中心的模式向以医院为中心的模式转移。随着当今人类对医学模式认识上的转变和以Ingernet为代表的信息技术的大普及，沿袭以久的以医院为中心的模式必将再次回归到以家庭、社区为中心的模式上来。传统医学仪器将面临这一巨大转变的挑战，为此我们必须有所准备。本文在回顾与分析的同时提出了有关对策建议。     

Mathematical modelling and prediction in infectious disease epidemiology

We discuss to what extent disease transmission models provide reliable predictions. The concept of prediction is delineated as it is understood by modellers, and illustrated by some classic and recent examples. A precondition for a model to provide valid predictions is that the assumptions underlying it correspond to the reality, but such correspondence is always limited—all models are simplifications of reality. A central tenet of the modelling enterprise is what we may call the ‘robustness thesis': a model whose assumptions approximately correspond to reality will make predictions that are approximately valid. To examine which of the predictions made by a model are trustworthy, it is essential to examine the outcomes of different models. Thus, if a highly simplified model makes a prediction, and if the same or a very similar prediction is made by a more elaborate model that includes some mechanisms or details that the first model did not, then we gain some confidence that the prediction is robust. An important benefit derived from mathematical modelling activity is that it demands transparency and accuracy regarding our assumptions, thus enabling us to test our understanding of the disease epidemiology by comparing model results and observed patterns. Models can also assist in decision-making by making projections regarding important issues such as intervention-induced changes in the spread of disease.     

AN IMPROVED BP NETWORK AND ITS APPLICATION

ＡＮＩＭＰＲＯＶＥＤＢＰＮＥＴＷＯＲＫＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＣｈｅｎｇｌｉｎＰｅｎｇ，ＤｉＸｉａｏ，ＥｒｘｉｎＺｈｅｎｇ（Ｄｅｐｔ．ｏｆＥｌｅｃｔｔｒｏｎｉｃＥｎｇｉｎｅｅｒｉｎｇＣｈｏｎｇｑｉｎｇＵｎｉｖｅｒｓｉｔｙｃｈｏｎｇｑｉｎｇ，...     

Drawbacks of Induction Methods for Synchronous Cell Growth: Simulation Techniques

A model of the bacterial cell cycle incorporating the processesof protein and DNA synthesis, due to Cooper and Helmstetter(1968), can be related to induction synchronization which employsthe blockage of DNA replication. Using a simulation technique,the model gives a reasonable degree of synchrony at slow growthrates, but the predicted synchronous growth curve disagreeswith the experimental and predicted synchronous curves due toMarr, Painter, and Nilson (1969). The model also fails severelyat fast growth rates and this suggests reasons for the failuresof the induction synchronous technique in some experiments whichemployed amino acid starvation. Investigations by the authorspoint to some fundamental shortcomings of this model, and leadthem to suggest that a more complex model, postulated by Donachie(1973), could provide an improvement in the predictions of synchronousgrowth curves obtained by simulation modelling. Simulation studiesoften lead to modifications of the model and assist in providinga better explanation of the mechanisms of the cell cycle. Thishas implications in resolving the ambiguities and difficultiessurrounding synchronization by induction methods.     

关于脑电偶极子源定位问题

从头皮脑电分布推算脑电活动源的脑电偶极子源定位问题的研究 ,对于脑认知功能的研究有重要的科学意义和临床应用价值。本文对偶极子源定位的一些问题 ,主要包括模型的选择、偶极子源定位的方法及源定位精确性等研究前沿进行概述。     

Gut-microbiota interactions in non-mammals: What can we learn from Drosophila?

Millions of people suffer from inflammatory diseases of the intestine, some of them potentiating gastrointestinal cancer. These gut-associated pathologies arise from imbalanced interactions between the host gut epithelia and resident or ingested microbes, interactions that are still poorly understood at the molecular level. Drosophila has been a very powerful model to study development and diseases. Its relatively simple tissue organization and sophisticated genetics are some of the advantages of using it as an experimental model to dissect gut-microbe interactions. Recent progress made in various research fields such as Drosophila microbiota composition, gut epithelium structure or gut immune reactions led us to believe that Drosophila is becoming an ad hoc model system to dissect the mechanisms that cooperate to maintain intestinal homeostasis in higher eukaryotes. It further may help us understand how an alteration of these finely tuned processes precipitates the inflammatory processes found in some inflammatory bowel diseases.