医学英文文献阅读-高殿帅课件.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,综 述,发展的轨迹（线索）,现状的总结（归纳）,指出存在的问题,提出解决问题的策略,不是今天要的内容！有机会再讲。,学术论文是某一学术课题在实验性、理论性或观测性上具有新的科学研究成果或创新见解的知识和科学记录,；或是某种已知原理应用于实际中取得新进展的科学总结，用以提供学术会议上宣读、交流或讨论；或在学术刊物上发表；或作其他用途的书面文件。,学术论文具有四大特点：学术性 科学性 创造性 理论性,医学,学术论文,学术论文（科研文章）,学术论文的形态结构（格式）,传递学术论文信息的语言单位,理解学术论文的三层境界,题 名,题名是以最恰当、最简,洁,的词语反映学术论文中最重要的特定内容的逻辑组合。,题名应该具有吸引力。,题名举例,Neural stem and progenitor cells retain their potential for proliferation and differentiation into functional neurons despite lower number in aged brain.,Radial glia-like cells persist in the adult rat brain.,Noggin expands neural stem cells in the adult hippocampus.,Upregulation of chemokine receptor expression by IL-10/IL-4 in adult neural stem cells.,题 名,注意,句法,结构：完整的句子,？,特定的词组,？,注意,内容,结构：处理因素,实验对象,实验效应（观察指标）,Death receptors and caspases but not mitochondria are activated in the GDNF-or BDNF-deprived dopaminergic neurons,题名分析,摘 要,20世纪60年代国外首先提出科技论文应附摘要，中华医学杂志英文版1972年也提出要求附摘要。,20世纪80年代加拿大温哥华一个研究小组进一步提出结构式摘要，即要求摘要写法分成四部分，分别冠以标题，使读者无需查阅正文即可基本了解实质性内容。,摘要具有独立性和自含性，即不阅读全文，就能获得必要的信息。,摘要一般应说明研究工作目的、,材料与,方法、结果,、,结论等，而重点是结果和结论。,摘 要,Death Receptors and Caspases But Not Mitochondria Are Activated in the GDNF-or BDNF-Deprived Dopaminergic Neurons,Neurotrophic factors,including glial cell line-derived neurotrophic factor(GDNF)and brain-derived neurotrophic factor(BDNF),promote survival of midbrain dopaminergic neurons,but the death pathways activated in the dopaminergic neurons by deprivation of these factors are poorly studied.We show here that deprivation of GDNF or BDNF triggers a novel mitochondria-independent death pathway in the cultured embryonic dopaminergic neurons:cytochrome c was not released from the mitochondria to cytosol,proapoptotic protein Bax was not activated,and overexpressed Bcl-xL did not block the death.Caspases were critically required,because the death was completely blocked by caspase inhibitor BAF boc-aspartyl(OMe)-fluoromethylketone and overexpression of dominant-negative mutants of caspase-9,-3,and-7 significantly blocked the death.Also,the death receptor pathway was involved,because blockage of caspase-8 or FADD(Fas-associated protein with death domain),an adapter required for caspase-8 activation,inhibited death induced by GDNF or BDNF deprivation.Ligation of Fas by agonistic anti-Fas antibody induced apoptosis in the GDNF-or BDNF-maintained neurons,and inhibition of Fas by Fas-Fc chimera blocked the death of GDNF-or BDNF-deprived neurons,whereas FAIML(long isoform of Fas apoptosis inhibitorymolecule)could control the activity of Fas in the dopaminergic neurons.,Neurotrophic factors,including glial cell line-derived neurotrophic factor(GDNF)and brain-derived neurotrophic factor(BDNF),promote survival of midbrain dopaminergic neurons,but the death pathways activated in the dopaminergic neurons by deprivation of these factors are poorly studied.,包括GDNF和BDNF在内的神经营养因子能促进中脑DA能神经元的存活，但很少有人研究，在这些DA能神经元内，由于剥夺这些营养因子而激活的细胞死亡信号通路是什么。,请翻译！,We show here that deprivation of GDNF or BDNF triggers a novel mitochondria-independent death pathway in the cultured embryonic dopaminergic neurons:cytochrome c was not released from the mitochondria to cytosol,proapoptotic protein Bax was not activated,and overexpressed Bcl-xL did not block the death.,这里，我们的结果显示：在体外培养的胚胎源DA能神经细胞，剥夺GDNF或BDNF，激活了这些细胞内一条新的非线粒体依赖性死亡信号通路。因为，没有细胞色素C从线粒体释放到胞浆、前凋亡蛋白Bax也没有被激活，且过表达Bcl-xL也不能阻止细胞的死亡。,Caspases were critically required,because the death was completely blocked by caspase inhibitor BAF boc-aspartyl(OMe)-fluoromethyl ketone and over expression of dominant-negative mutants of caspase-9,-3,and-7 significantly blocked the death.Also,the death receptor pathway was involved,because blockage of caspase-8 or FADD(Fas-associated protein with death domain),an adapter required for caspase-8 activation,inhibited death induced by GDNF or BDNF deprivation.,但是，Caspases是必需的，因为，细胞死亡能被caspase抑制剂BAF（boc-aspartyl(OMe)-fluoromethyl ketone）完全阻断；caspase-9、-3、和-7的显性负突变体的过表达也能显著地阻滞细胞死亡。此外，死亡受体通路也参与了细胞死亡过程，因为，caspase-8或FADD（Fas相关蛋白细胞死亡结构域），一种caspase-8激活的必需接头蛋白，同样能抑制因GDNF或BDNF剥夺而致的细胞死亡。,Ligation of Fas by agonistic anti-Fas antibody induced apoptosis in the GDNF-or BDNF-maintained neurons,and inhibition of Fas by Fas-Fc chimera blocked the death of GDNF-or BDNF-deprived neurons,whereas FAIM(L)(long isoform of Fas apoptosis inhibitory molecule)could control the activity of Fas in the dopaminergic neurons.,由具有激动剂性质的抗Fas抗体与Fas结合可引发,在GDNF或BDNF维持,存活,下的,神经元,的,凋亡，由Fas-Fc嵌合体抑制Fas的作用则能阻滞由GDNF或BDNF剥夺引起的神经元死亡，相反，FAIM(L)（Fas,凋亡抑制,分子的长,异构体,？,）能控制DA能神经元中的Fas活性。,请说出该摘要中下列几部分是怎样表达的？,目的,材料和方法,结果,结论,Death receptors and caspases but not mitochondria are activated in the GDNF-or BDNF-deprived dopaminergic neurons,Neurotrophic factors,including glial cell line-derived neurotrophic factor(GDNF)and brain-derived neurotrophic factor(BDNF),promote survival of midbrain dopaminergic neurons,but the death pathways activated in the dopaminergic neurons by deprivation of these factors are poorly studied.,We show here that deprivation of GDNF or BDNF triggers a novel mitochondria-independent death pathway in the cultured embryonic dopaminergic neurons,:cytochrome c was not released from the mitochondria to cytosol,proapoptotic protein Bax was not activated,and overexpressed Bcl-xL did not block the death.,Caspases were critically required,because the death was completely blocked by caspase inhibitor BAF boc-aspartyl(OMe)-fluoromethylketone and overexpression of dominant-negative mutants of caspase-9,-3,and-7 significantly blocked the death.,Also,the death receptor pathway was involved,because blockage of caspase-8 or FADD(Fas-associated protein with death domain),an adapter required for caspase-8 activation,inhibited death induced by GDNF or BDNF deprivation.Ligation of Fas by agonistic anti-Fas antibody induced apoptosis in the GDNF-or BDNF-maintained neurons,and inhibition of Fas by Fas-Fc chimera blocked the death of GDNF-or BDNF-deprived neurons,whereas FAIM(L)(long isoform of Fas apoptosis inhibitory molecule)could control the activity of Fas in the dopaminergic neurons.,引 言,引言又称前言，属于整篇论文的引论部分。其写作内容包括：研究的背景、现状，存在的问题，提出解决问题的策略（自己的创新点），阐述所提策略的理论依据和实验基础，主要研究内容。,引言的文字不可冗长，内容选择不必过于分散、琐碎，措词要精炼，要吸引读者读下去。,言简意赅，不要与摘要雷同，不要成为摘要的注释。一般教科书中有的知识，在引言中不必赘述。,Most neuronal populations undergo a period of ontogenetic death during which the initially overproduced neurons are reduced to the final number by target-derived neurotrophic factors(Barde,1989;Oppenheim,1991).The intrinsic death program of the neurons is suppressed by neurotrophic factors or,conversely,released in their absence(Johnson and Deckwerth,1993;Chang et al.,2002).The molecular nature of this program is,however,poorly described for different neuronal types.,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,Survival of the midbrain dopaminergic(DA)neurons that degenerate in Parkinsons disease is potently promoted by glial cell line-derived neurotrophic factor(GDNF)in vitro(Lin et al.,1993;Burke et al.,1998),in vivo(Oo et al.,2003,2005),and in,several models of Parkinsons disease(Airaksinen and Saarma,2002;Bespalov and Saarma,2007;Lindholm et al.,2007).GDNF binds to coreceptor GFR1,and this complex activates receptor tyrosine kinase Ret(Bespalov and Saarma,2007).Genetic manipulations of Ret in the DA neurons(Granholm et al.,2000;Jain et al.,2006;Kramer et al.,2007;Mijatovic et al.,2007)have given controversial results whether and/or when Ret physiologically regulates survival/death of DA neurons.Treatment of Parkinsons patients with GDNF has also been contradictory,because some studies reported considerable improvement(Gill et al.,2003;Slevin et al.,2005),whereas others did not(Lang et al.,2006).These contradictions require further studies.,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,Brain-derived neurotrophic factor(BDNF),a member of the neurotrophin family,also promotes survival of DA neurons(Krieglstein et al.,1996;Baquet et al.,2005)but via a different receptor tyrosine kinase,TrkB.The physiological role of BDNF in the ontogenetic(Kramer et al.,2007)or pathological(Baquet et al.,2005;Sun et al.,2005)death/survival of DA neurons is poorly understood.,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,Classically,apoptosis occurs via either death receptor or mitochondrial pathway(Danial and Korsmeyer,2004;Thorburn,2004;Riedl and Salvesen,2007).Ligated death receptors recruit and activate apical procaspase-8 via adapters as Fas-associated protein with death domain(FADD)(Peter and Krammer,2003;Peter et al.,2007).In the mitochondrial pathway,activated proapoptotic proteins(e.g.,Bax)release proteins(including cytochrome c)from the mitochondria to the cytosol,leading to the assembly of an apoptosome and activation of apical caspase-9.,Apical caspases cleave and activate executionary caspase-3,-6,and-7,which ultimately demolish the cell(Shacka and Roth,2006;Riedl and Salvesen,2007).Some caspases(e.g.,caspase-2)are activated via a different but poorly characterized mechanism(Troy et al.,2000;Baliga et al.,2004).Also,some nonclassical caspase-dependent apoptotic pathways have been described,(Mehlen et al.,1998;Bredesen et al.,2006).,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,We recently showed that in the GDNF-deprived sympathetic neurons,caspase-2 and-7 are activated via a novel pathway without mitochondria and death receptors:Bax is not translocated to the,mitochondria;cytochrome c is not released to the cytosol and caspase-9 and-3,but also caspase-8 and FADD are not involved,(Yu et al.,2003).Here,we addressed the death pathways in GDNF-and BDNF-deprived DA neurons.In both cases,the neurons died via a nonclassical apoptotic pathway in which death receptors and caspases,but not mitochondria,were activated.,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,材料和方法,Cultures of 13-d-old mouse ventral mesencephalon and survival assays.,Transfections.,Immunocytochemistry.,Reverse transcription-PCR.,Immunoblot and coimmunoprecipitation.,结 果,为假说提供证据！,这篇文章的假说是什么？,Here,we addressed the death pathways in GDNF-and BDNF-deprived DA neurons.In both cases,the neurons died via a nonclassical apoptotic pathway in which death receptors and caspases,but not mitochondria,were activated.,结 果（研究内容）,Embryonic dopaminergic neurons die in culture because of GDNF or BDNF deprivation,Mitochondrial death pathway is not activated in GDNF-and BDNF-deprived dopaminergic neurons,Caspases are required for the death of GDNF-or BDNF-deprived dopaminergic neurons,The death receptor pathway is activated in GDNF-and BDNF-deprived dopaminergic neurons,Death receptors and caspases but not mitochondria areactivated in the GDNF-or BDNF-deprived dopaminergic neurons,讨论：从结果到结论的过程！,具有以下几个主要特征：,只对“结果”进行论述，而不应进行重述。,论述其是怎样支持“结论”的。,要能指出你的结果和解释与以前发表的著作相一致或不一致的地方。,要论述你的研究工作的理论含义以及实际应用的各种可能性。,要能指出任何的例外情况或相互关系中有问题的地方，并且应明确提出尚未解决的问题及解决的方向。,讨 论,We have previously shown that GDNF-deprived sympathetic neurons activate caspases via a novel mitochondria-independent death pathway(Yu et al.,2003).,Here we show that also the embryonic DA neurons do not activate mitochondrial death pathway by deprivation of GDNF(but also BDNF):,Bax is not translocated to the mitochondria and Bax inhibition does not block the death,cytochrome c is not released to the cytosol,and antiapoptotic mitochondrial protein Bcl-xL does not block the death.In the immunostaining experiments,we had to prevent cell death by caspase inhibition,because the changes in the localization of Bax and cytochrome c occur only briefly before death and were almost impossible to detect.The apoptotic mitochondrial changes are believed to occur without caspase involvement(Chang et al.,2002;Gogvadze et al.,2006),but caspase-2 is reported to be activated upstream of mitochondria(Guo et al.,2002;Lassus et al.,2002;Robertson et al.,2004).We cannot exclude that caspase inhibition affected the movement of Bax and cytochrome c in our factor-deprived neurons.However,caspase-2 was not critical for the death of DA neurons.Moreover,experiments with Ku70 or Bcl-xL were performed without caspase inhibitors.We therefore conclude that,mitochondria were not activated in the neurotrophic factor-deprived DA neurons.,Caspases were still absolutely required for the death of GDNF-and BDNF-deprived DA neurons,.,When compared with the GDNF-deprived sympathetic neurons,the involved caspases were completely different:caspase-2 was critical for the death of GDNF-deprived sympathetic neurons but not GDNF-deprived DA neurons.Instead,the DA neurons died via caspase-9,-3,and-7,which were not essential in the sympathetic neurons.How caspase-9 is activated without cytosolic cytochrome c remains an open question.Caspase-9 is activated at the apoptosome by dimerization(Boatright et al.,2003;Pop et al.,2006),but it is also cleaved in the apoptotic cells,which enhances its catalytic activity(Bao and Shi,2007;Riedl and Salvesen,2007).We speculate that caspase-8,activated at the death receptors,could cleave and activate caspase-9 in our neurons,as recently shown in other systems(McDonnell et al.,2003;Gyrd-Hansen et al.,2006).Indeed,blockage of caspase-8 prevented the death of the neurons,suggesting that caspase-9 is activated downstream of caspase8.Our attempts to visualize cleavage products of the caspases by Western blotting failed,most probably because of the small amount of the material available.Immunostaining of the cultures with antibodies to activated caspases also did not give consistent results in our hands.Thus,further studies are required to understand caspase-9 activation in our model.,Death receptors were activated in the GDNF-and BDNF-deprived DA neurons,because the death was significantly blocked by inhibition of caspase-8 or FADD,but also with overexpression of Fas inhibitor FAIML.Fas agonists and antagonists as well as the PCR results strongly suggest the existence of functional Fas-like receptor on the surface of the DA neurons,and its activation by GDNF or BDNF deprivation.Most probably the Fas and FasL interact via neuritic contacts that are extensive in our dense cultures,as also suggested for trophic factor-deprived motoneurons(Raoul et al.,1999;Ugolini et al.,2003;Raoul et al.,2006).Fas and FasL were constitutively present in the midbrain cultures,suggesting that an inhibitory system should prevent the unwanted activation of Fas.Indeed,we found that a neuron specific inhibitory protein FAIML(Segura et al.,2007)was expressed in the midbrain cultures.FAIML interacts with Fas,both physically,as revealed by coimmunoprecipitation,and functionally,as revealed by transfection of DA neurons.Thus,the findings of Segura et al.(2007)were repeated in our model.It is tempting to speculate that in the healt