猪脊髓前角匀浆免疫后豚鼠脊髓前角运动神经元的超微病理特征

应用透射电子显微镜观察猪脊髓前角匀浆免疫后豚鼠脊髓前角运动神经元的超微结构改变,并进一步探讨其发病机制。结果显示：免疫后豚鼠脊髓前角运动神经元可见内质网扩张、线粒体肿胀;胞浆基质及细胞器致密化;有髓神经纤维内神经丝局部积聚、大量线粒体及溶酶体聚集;前根及坐骨神经大的有髓神经纤维轴索萎缩,髓鞘结构保存相对较好。以上结果提示自身免疫机制能诱导脊髓前角运动神经元的损伤,轴浆转运异常可能参与其致病过程。     

免疫介导豚鼠脊髓运动神经元损伤的超微结构及钙稳衡改变

应用常规透射电镜及草酸盐-焦亚锑酸盐技术原位固定细胞内钙,对豚鼠脊髓前角细胞内的钙分布进行超微定位,探讨钙稳衡改变在免疫介导运动神经元损伤中的作用.结果发现模型组豚鼠脊髓前角运动神经元可见粗面内质网扩张、线粒体肿胀、嵴排列紊乱等.神经元周围胶质细胞增生.在运动神经元扩张的粗面内质网池和线粒体内室可见数量不等颗粒状电子致密的钙沉积物.线粒体内室内钙沉积颗粒与线粒体肿胀的程度相关.星形胶质细胞内肿胀的线粒体内室及扩张的粗面内质网池内也可见电子致密钙沉积颗粒.因此认为,钙稳衡失调参与了免疫介导的运动神经元损伤过程.     

钒酸盐对神经元内NF—H及NLY的影响

ＳＤＳ电泳表明神经丝蛋白 (ＮＦＰｓ)分为 :ＮＦ Ｈ ,ＮＦ Ｍ ,ＮＦ Ｌ三种 ,ＮＦ Ｈ的出现是神经元成熟的标志。神经元中线状溶酶体 (ｎｅｍａｔｏｌｙｓｏｓｏｍｅＮＬＹ)的存在与神经元的功能有着密切的关联 ,轴突内不能合成所需的物质 ,可以通过溶酶体及其前体实现轴浆运输。有关二者的关系目前还不清楚 ,对于神经丝功能的了解也还处于摸索阶段。本实验采用单克隆抗体免疫电镜及酶电镜技术标识ＮＦ Ｈ及ＮＬＹ的分布 ,利用低浓度的钒酸盐 ,观察神经丝及溶酶体的变化 ,推测神经丝蛋白的磷酸化、神经丝的解聚及溶酶体分布变化的关系与机…     

人胎儿脊髓前角运动神经元NLY的电镜观察

人胎儿脊髓前角运动神经元ＮＬＹ的电镜观察＊任昊石玉秀（中国医科大学组胚教研室，沈阳１１０００１）＊国家自然科学基金资助项目（Ｎｏ．３９５７０３７７）我们利用酶细胞化学方法曾对大鼠、豚鼠中枢神经细胞的线状溶酶体（Ｎｅｍａｔｏｌｙｓｏｓｏｍｅ，ＮＬＹ）进...     

青少年特发性脊柱侧凸患者脊柱前后柱生长软骨的超微结构研究

探讨青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者脊柱生长的特征,对12例AIS患者的前后柱生长软骨进行超微结构观察。结果显示12例AIS患者脊柱前后柱均有软骨内成骨,电镜下观察脊柱前柱(终板)软骨细胞呈圆形且表面有突起,胞浆内粗面内质网和线粒体丰富;后柱生长软骨细胞呈梭形细胞表面有突起,胞浆内粗面内质网和线粒体相对较少,细胞核有异染色质聚集。超微结构的观察有助于青少年特发性脊柱侧凸的病因学诊断研究。     

激光照射对急性脊髓损伤后脊髓再生的促进作用

建立大鼠皮质脊髓背侧束全横断模型,利用弱激光照射脊髓受损部位的皮肤,观察激光照射对急性脊髓损伤后脊髓再生的促进作用.30只SD大鼠,随机分成对照组和照射组.照射组:急性皮质脊髓背侧束全横断后15 min进行连续14 d采用弱激光照射脊髓受损部位的皮肤.对照组:急性皮质脊髓背侧束全横断后未行弱激光经皮照射治疗.术后两组分别于第3,7,14 d分别取材,用苏木精-伊红染色法(HE)染色和免疫荧光标记染色观察.实验发现,脊髓损伤后14 d,照射组的空洞及瘢痕形成面积小于对照组,有统计学差异(p<0.05);对照神经胶质酸性组蛋白(GFAP)和硫酸软骨素(CS)表达强烈分布紧密,照射组GFAP和CS56表达达微弱且分布稀疏;对照组少量神经微丝蛋白(NF)在损伤区周围,神经生长相关蛋白(GAP43)形态肿大变形分布紊乱,照射组大量成纤维丝状的NF分布在损伤区周围,并与GAP43相伴行.结果表明,脊髓损伤急性期采用弱激光照射脊髓受损部位的皮肤,可减少脊髓损伤后空洞形成,并促进轴突再生.     

脊髓前角运动神经元GR受体免疫电镜观察

近年肾上腺皮质激素的糖皮质激素受体 ( Glucocorticoid receptor.GR)在脑神经细胞分布与作用的研究已倍受关注[1] ,脊髓 GR受体的分布尚未见报道 ,本研究采用免疫组织细胞化学方法对 GR受体在脊髓前角运动神经元的超微结构定位进行了电镜观察 ,为进一步探讨 GR受体对脊髓功能的作用机制提供形态学依据。材料与方法　实验动物为成熟 Wistar大鼠 (体重 2 5 0～ 30 0 g) ,全身麻醉下 ,用 4%多聚甲醛( 0 .1 mol/ L PBS缓冲液配制 )固定液心脏灌流固定 ,摘出脊髓 ,用同种固定液再继续浸泡固定一夜 ,同上缓冲液洗净标本 ,采用 microslicer(…     

Creutzfeldt-Jakob病二例电镜观察

本实验用透射电镜观察了二例Ｃｒｅｕｔｚｆｅｌｄｔ－Ｊａｋｏｂ病（ＣＪＤ）的尸检及活检脑组织。其中一例为死后６天尸检脑组织,电镜下可见神经元及神经胶质细胞明显变性,核染色质块状凝集,核碎裂,可见细胞碎片。另一例为穿刺活检脑组织,因取材过少光镜病理检查只发现脑组织水肿,不能明确诊断,电镜观察二例均少见神经元,神经胶质细胞多见且变性,最突出的表现为脑组织的海绵状界膜空泡变性,有髓神经纤维髓鞘解离并有部分溶解,轴索溶解消失并呈空泡样变性。本实验表明：对临床上表现为进行性痴呆,脑电图广泛异常的病人的组织活检,送检组织过少,一般病理检查不能明确诊断时,电镜检查具有重要意义,即使是死亡６天后的尸检仍可为ＣＪＤ这种疑难和罕见病例的确诊提供有力的证据。     

海马神经元的原子力显微成像

原子力显微镜(AFM)对完整的细胞成像并同时进行微细结构观察尚有一定困难。本实验改进了标本制备的过程．用原子力显微镜对戊二醛固定的海马神经元进行扫描，建立了方便、实用的完整海马神经元自完整胞体至超微结构的原子力显微镜成像技术，并用改进的方法获得了完整海马神经元及其超微结构的清晰的三维成像，并发现了一些其它显微技术所不能发现的微细结构。这些结构包括：①海马神经元胞体的亚细胞部分及这些亚细胞部分所具有的不同功能；②神经突触的完整形态；③损伤细胞膜表面出现的孔洞；④通过神经突触所形成的神经网络结构。     

db—cAMP对脑缺血再灌注大鼠皮质脊髓束可塑性及运动功能恢复的影响

目的：研究双丁酸环腺苷酸（db—cAMP）对脑缺血再灌注大鼠神经结构可塑性及运动功能恢复的影响,并对其发生机制进行探讨。方法：采用Longa改良线栓法制备大鼠右侧大脑中动脉缺血再灌注模型,造模成功的大鼠20只随机分为实验组（10只）和对照组（10只）,参照Montoya设计的“楼梯测试”对大鼠运动功能进行定量评定,BDA顺行性示踪方法观察皮质脊髓束可靼性变化。结果：大鼠运动功能实验组较对照组明显改善,BDA顺行性示踪见颈膨大处跨过脊髓中线支配患侧前角的纤维数量较对照组明显增加。结论：db—cAMP能够促进脑缺血再灌注损伤大鼠神经结构可塑性的改善和运动功能的恢复。     

大鼠坐骨神经再生过程中的神经元轴突自噬作用

目的：探讨大鼠坐骨神经变性轴突清除中的自噬作用。方法：横切大鼠坐骨神经制作wallerian变性模型,造模后不同时间点取远断端组织行电镜结构观察和酸性磷酸酶(AcPase)活性检测。结果：坐骨神经横切后轴突发生变性,主要变化为术后第5h～2d轴质肿胀,轴突与髓鞘分离,术后第4d轴质浓缩,轴突与髓鞘完全分离形成游离轴突体。术后初期变性轴突主要形成大小不等的空泡,后期轴突与髓鞘完全分离并形成较大的游离轴突体,轴突体外包一层轴突膜是神经元细胞膜的延续,轴突体轴质浓缩,含大量各级自噬泡和纵横交错的神经丝、微管和微丝。经酸性磷酸酶(AcPase)染色证实自噬泡均呈AcPase阳性,第7d后轴突体被降解吸收,形成的空腔内偶见巨噬细胞。结论：大鼠坐骨神经再生过程中变性轴突的清除主要靠轴突自身的自噬和施万细胞吞噬机制,而巨噬细胞只起辅助作用。     

Neutrophil Decoys with Anti-Inflammatory and Anti-Oxidative Properties Reduce Secondary Spinal Cord Injury and Improve Neurological Functional Recovery

Following spinal cord injury (SCI), immune cell infiltration creates an inflammatory and oxidative microenvironment (known as the secondary injury), which causes neuron death and spinal cord damage, and dramatically hinders neurological functional recovery. Strategies that inhibit the infiltration and/or function of neutrophils offer promises for SCI treatment because they can reduce the secondary injury; however, such strategies remain largely unexplored. Herein, a strategy using neutrophil membrane-coated nanoparticles (NPs) as decoys (neutrophil decoy, ND) is presented to reduce local neutrophil infiltration and relieve oxidative stress in the injured spinal cord after SCI. Coated with membranes of activated neutrophils, the NDs inherit multiple receptors from the “parent” neutrophils, which can adsorb and neutralize the elevated neutrophil-related cytokines. In addition, polydopamine NPs with multi-antioxidative properties (selected as the core for ND) scavenge excessive reactive oxygen and nitrogen species. In a contusion model of SCI, ND treatment significantly reduces neutrophil infiltration and reprograms the inflammatory and oxidative microenvironment in injured spinal cords. Importantly, ND treatment significantly improves neural regeneration and functional recovery in rats. Such a nano-decoy platform opens up new approaches for efficiently treating SCI.     

血管性痴呆小鼠海马神经元超微病理特征研究

目的：探讨血管性痴呆(VD)小鼠海马神经元超微病理特征及其变化的意义。方法：采用双侧颈总动脉线结、反复缺血—再灌注法,制作小鼠VD动物模型。取两组小鼠海马组织制成超薄切片,透射电镜观察。结果：(1)假手术组：海马神经元和神经毡结构均正常。(2)VD模型组：海马神经元核肿胀、有局部凹陷现象;核周体细胞器明显减少,多聚核糖体稀散;仅残留受到破坏的高尔基体和粗面内质网、线粒体变性。髓鞘层裂;轴突中神经微管结构模糊。神经毡中可见树突和轴突不同程度水肿,尤其是树突呈现极度扩张形成不规则的“气球”,其中含有许多大小不等的薄膜空泡。突触数量显著减少,可见穿孔和异形的突触;有的突触小泡破裂,呈片状均质化。结论：海马神经元的超微结构病变导致神经元功能异常、突触可塑性降低,可能在VD的病因中起重要作用。     

Training Neural Stem Cells on Functional Collagen Scaffolds for Severe Spinal Cord Injury Repair

Neural stem cells (NSCs) transplantation is regarded as a promising therapeutic strategy to treat severe spinal cord injury (SCI) by compensating the neuronal loss. However, significant challenges including long‐term survival, directed neuronal differentiation, and functional integration of the transplanted NSCs and their progenies within the host spinal cord are yet to be solved. In this study, NSCs are trained on differently modified collagen scaffolds to increase their neuronal differentiation rate when cultured under the simulated SCI microenvironment. Then, a functional scaffold is screened out, on which the cultured NSCs show high neuronal differentiation rate and generate both sensory and motor mature neurons. Subsequently, that NSC seeded functional scaffold is transplanted into a rat severe SCI model. The results show that higher endogenous neurogenesis efficiency as well as in vivo survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, both sensory and motor neurons are found to be differentiated from the grafted NSCs in the lesion site and those newly generated neurons can functionally interact with each other and the host neurons. Taken together, the in vitro training systems for modulating the differentiation profiles of NSCs are instructive and exhibit strong potentials for SCI treatments.     

Polymer Fiber Probes Enable Optical Control of Spinal Cord and Muscle Function In Vivo

Restoration of motor and sensory functions in paralyzed patients requires the development of tools for simultaneous recording and stimulation of neural activity in the spinal cord. In addition to its complex neurophysiology, the spinal cord presents technical challenges stemming from its flexible fibrous structure and repeated elastic deformation during normal motion. To address these engineering constraints, we developed highly flexible fiber probes, consisting entirely of polymers, for combined optical stimulation and recording of neural activity. The fabricated fiber probes exhibit low‐loss light transmission even under repeated extreme bending deformations. Using our fiber probes, we demonstrate simultaneous recording and optogenetic stimulation of neural activity in the spinal cord of transgenic mice expressing the light sensitive protein channelrhodopsin 2 (ChR2). Furthermore, optical stimulation of the spinal cord with the polymer fiber probes induces on‐demand limb movements that correlate with electromyographical (EMG) activity.     

Detection and classification of sensory information from acute spinal cord recordings

One avenue of research for partial restoration of function following spinal cord injury is the use of neural prostheses, an example of which is functional electrical stimulation (FES) devices for motor functions. Neural prostheses may also be useful for the extraction of sensory information directly from the nervous system. We suggest the spinal cord as a possible site for the detection of peripheral sensory information from neural activity alone. Acute multichannel extracellular recordings were used to extract neural spike activity elicited from peripheral sensations from the spinal cords of rats. To test the recording method and classification potential, eight classes of sensory events were recorded consisting of electrical stimulation of seven locations on rat forepaws, and another class of data during which no stimulus was present. A dual-stage classification scheme using principal component analysis and k-Means clustering was devised to classify the sensory events during single trials. The eight tasks were correctly identified at a mean accuracy of 96%. Thus, we have shown the methodology to detect and classify peripheral sensory information from multichannel recordings of the spinal cord. These methods may be useful, for example, in a closed-loop FES for restoration of hand grasp.     

中脑导水管周围灰质支配桥脑Barrington''''s核内骶髓投射神经元的电镜双标记研究

本文研究采用电镜双标记技术对大鼠中脑导水管周围灰质神经元投射到桥脑Barrington's核的轴突与该核内投射到骶髓的神经元的胞体和树突之间的突触关系进行了探讨.将生物素标记的葡聚糖胺(BDA)注射于中脑导水管周围灰质用来标记它发出的轴突终末,将辣根过氧化物酶(HRP)注射于脊髓的骶髓部分,用来标记Barrington's核内投射至骶髓的神经元.显色后透射电镜观察发现,BDA标记的轴突终末与HRP标记的胞体和树突间存在直接的突触联系.此结果提示中脑导水管周围灰质在脑桥排尿反射中可能起着重要的作用.