大鼠脊髓损伤后感觉、运动及电生理变化

在应用磁控机械夹断法复制的大鼠脊髓损伤模型上,动态地观察了脊髓损伤后的感觉及运动机能变化,并进行了电生理学研究。结果表明,0.3A电流未能导致永久性瘫痪。术后2周,后肢的感觉及运动功能逐渐恢复;可记录到体感诱发电位(SEP)。0.4,0.5和0.8A电流均能导致大鼠永久性瘫痪;倾斜板及开阔场地行走分数均显著低于0.3A组;术后4周这些大鼠可产生行走样动作,于损伤部位再次切断脊髓后仍能出现这些动作;0.4A组可记录到早期SEP,再次切断脊髓后SEP消失。结果提示:(1)脊髓不全横断后,由于残留纤维活动,可在相当程度上导致大鼠感觉和运动机能的恢复;(2)脊髓完全横断后,后肢的上行冲动可能经再生的神经纤维向中枢端传导至脑;(3)大鼠脊髓内可能存在行走中枢模式发生器(CPG),适当刺激可激发其活动,并产生行走样运动。     

大鼠脊髓背角神经元中酸敏感离子通道的特性和功能研究

酸敏感离子通道（ASICs）是一类能被细胞外酸所激活的配体门控离子通道。本文综合报道大鼠脊髓背角神经元中ASICs的亚基组成及其功能性调节：（1）脊髓背角主要表达ASIC1a、ASIC2a和ASIC2b,但不表达ASIC1b和ASIC3;（2）在脊髓背角神经元中酸诱导电流可能由ASIC1a同聚体通道所介导;（3）胞外痛觉信号如实验性缺血和神经肽FMRF可以通过不同的机制增强脊髓背角神经元酸诱导电流;（4）炎症痛可以上调脊髓背角ASICs在转录和蛋白水平的表达。上述各点提示,在生理或病理情况下脊髓背角ASICs对脊髓水平的感觉信息传递特别是痛觉的传导可能发挥着重要作用。     

脊髓背角胶状质神经元形态与电生理学特性的研究进展

脊髓背角胶状质神经元在痛信息传递过程中具有重要作用。其形态学分类及电生理学特性复杂,形态学大体上可分为岛神经元、中央神经元、放射状神经元、垂直神经元以及不能分类神经元;电生理学主要包括被动膜特性(静息电位、膜电容和膜电阻)、主动膜特性(动作电位,包括其放电模式、阈值、基电流、半宽度、振幅等)以及兴奋性或抑制性突触后电流等。本文对国内外脊髓背角胶状质神经元形态学与电生理学的研究进展予以综述。     

刺激兔中脑导水管周围灰质对束旁核单位放电的影响

实验在65只家兔进行。局麻下进行手术准备,筒箭毒素麻痹下进行实验观察。用玻璃微电极记录束旁核单位放电,以腓总神经的强电流刺激(30—50伏)作为损伤性刺激。根据对外周损伤性刺激反应的不同,在束旁核单位中可区分出两类功能不同的神经元,一类的自发放电可因外周痛信号的传入而增强,称为痛敏神经元;一类的自发放电可因外周痛信号的传入而减少,称为痛抑制神经元。中脑导水管周围灰质的弱电流刺激(4—6伏)或吗啡静注(3毫克/公斤体重),可使痛敏神经元对外周损伤性刺激的痛反应减弱或消失,却可使痛抑制神经元因痛传入而出现的自发放电的抑制现象减弱或不再出现。刺激中脑中央灰质或吗啡注射对束旁核痛敏神经元的上述影响,在脊髓胸_(12)或腰_1段的背侧1/2被切断后仍然能出现。由于多数实验证明脑干对脊髓痛传递的下行抑制系统是在脊髓背外侧束中下行的,因此我们的实验提示,中脑结构有可能通过上行性联系抑制束旁核神经元对痛传入的反应;吗啡似乎也能通过这一联系实现其镇痛作用。     

可视膜片钳法记录初级传入纤维介导的脊髓背角神经元突触后电流

本文描述了用明胶半包埋法制备带背根脊髓薄片的实验步骤,和在脊髓背角记录由初级传入纤维介导的突触后电流的可视膜片钳法。手术制备一段带背根的脊髓标本,并用20％的明胶包埋在琼脂块上,再用振动切片机切片获得带背根的脊髓薄片。通过红外线可视的引导,在脊髓背角神经元上建立全细胞封接模式。在钳制电压为-70mV条件下,记录自发的和背根刺激引起的兴奋性突触后电流。以传入纤维的传导速度与刺激阈值为指标,可以区分A样纤维与C样纤维兴奋性突触后电流。在钳制电压为0mV条件下,记录自发的和背根刺激引起的抑制性突触后电流。用5μmol／L的士宁或20μmol／L的荷包牡丹碱分离出γ-氨基丁酸能或甘氨酸能的抑制性突触后电流。用可视膜片钳方法可以准确测量脊髓背角神经元的突触后电流,从而研究初级传入突触的传递过程。更重要的是,在红外线可视观察的帮助下,建立膜片钳封接的成功率显著提高,同时也使记录研究脊髓背角深层神经元变得更加容易。本研究为探索初级传入突触传递过程提供了一个有效的方法。     

家兔脊髓背半部下行抑制通路中递质作用的补充观察

用玻璃微电极记录了麻痹而清醒的家兔束旁核单位对腓总神经强电流刺激发生的痛敏放电,看到此放电可被已在 L_1—L_2水平切断的脊髓背半部外周端的电流刺激所抑制。在14个可被脊髓刺激明显抑制的痛敏单位中,此脊髓刺激效应在8个单位可因静脉注射酚妥拉明而阻断,其余6个单位则基本不受酚妥拉明注射的影响。进一步观察表明,在8个酚妥拉明有阻断作用的单位,其中7个单位在注射赛庚啶时不表现阻断作用;而在6个酚妥拉明不起阻断作用的单位,注射纳洛酮也不能阻断其脊髓刺激效应。由于我们在过去的工作中已经证明,凡是酚妥拉明有阻断作用的单位注射纳洛酮也都表现出阻断作用,而酚妥拉明无阻断作用的单位对注射赛庚啶却有阻断作用。因而本组实验结果支持我们已提出的推论,即在家兔脊髓背半部下行抑制通路中至少包含两类纤维,一类以内源性吗啡和去甲肾上腺素为递质或调制物,另一类以5-羟色胺为递质。     

延脑心血管中枢的下行通路

在狗、猫和兎三种动物研究了延脑心血管中樞的脊髓下行通路。在脊髓第一和第二頸节間切断两侧背侧索,刺激延脑第四脑室附近或反射性引起的加压和减压反应都仍保留。进一步切断除了腹侧索以外的脊髓各部分,也不影响这些反应。如只切断两侧腹侧索而保留脊髓其他部分完整,上述反应都消失。看来,延脑心血管中樞的下行通路主要都是在脊髓腹侧索內,而不是如林可胜等所描述的加压和减压通路分別存在于脊髓的腹侧索和背侧索內。文中討論了我們的結果和林等的結果不同的可能的原因。     

颈前路手术治疗脊髓型颈椎病的护理体会

脊髓型颈椎病是由于颈脊髓受到刺激、压迫或者脊髓的动脉血管受到刺激压迫后,使脊髓血液供应不足,从而导致脊髓的功能障碍。临床上可引起单侧或双侧肢体软弱无力,有麻木感,甚至行走困难,躯干有约束感,严重者可致四肢瘫痪,大小便功能障碍,严重影响病人的工作和生活。     

一种自动化的植物细胞壁伸展性能测定仪及其应用

应用实验室常用仪器和电子部件,包括直流稳压电源、等臂双盘天平、记录仪、恒流泵、程控仪、线性可变差动变压器（LVDT）、电磁间等,改装和配置成的植物细胞壁伸展性能测定仪,具有操作简便、测量准确和灵敏度高等优点;对大豆幼苗下胚轴生长区细胞壁的内源伸展活性和重组伸展活性的实测结果与文献报告相符,表明该仪器是一种较为理想的准确测定植物细胞壁伸展性能的自动化仪器。     

两种构建小鼠脊髓击打损伤模型仪器的比较和探讨

目的通过比较两种构建小鼠脊髓击打损伤模型仪器各自的特点和优势,以期探索脊髓击打损伤模型建立的标准化。方法 40只小鼠随机分为两组,分别采用自制Allen脊髓打击器(A组,n=20)和Impactor M-Ⅲ脊髓撞击器(B组,n=20)进行击打,建立小鼠脊髓损伤模型。术后,于1d、3d、5d、7d、14d、21d六个时间节点,采用BBB运动功能评分对小鼠下肢恢复情况进行评估,记录数据。并在3d、7d、14d、21d四个时间节点取实验小鼠脊髓损伤处进行HE染色。结果两组脊髓损伤模型在1d、3d、5d、21d四个时间节点恢复情况无明显差异(P0.05)。而在7d、14d,B组小鼠的脊髓损伤恢复状况明显优于A组,差异具有统计学意义(P0.05)。在组织形态切片上差异不大。结论两种击打脊髓的实验仪器均可成功建立小鼠的脊髓损伤模型,采用Impactor M-Ⅲ脊髓撞击器构建的脊髓击打损伤模型小鼠恢复较自制Allen脊髓打击器更快速、稳定。     

Changes in levels of the tripeptide Tyr-Gly-Gly as an index of enkephalin release in the spinal cord: effects of noxious stimuli and parenterally-active peptidase inhibitors

The tripeptide Tyr-Gly-Gly (YGG), representing the product of enkephalin hydrolysis by enkephalinase (EC 3.4.24.11), was characterized and its levels measured in spinal cord perfusates of halothane-anaesthetized rats. During noxious pinching of the muzzle, which is known to trigger enkephalin release, YGG levels were enhanced more markedly and for longer than were those of [Met5]enkephalin (YGGFM), in the same samples. By contrast, neither YGG nor YGGFM levels were affected by pinching the tail. Treatment with carbaphethiol, a parenterally-active aminopeptidase inhibitor, markedly increased YGG levels and lengthened the duration of the increase produced by pinching the muzzle. Treatment with acetorphan, a parenterally-active enkephalinase inhibitor, given alone or in combination with carbaphethiol, completely prevented the rise in YGG triggered by noxious stimulation. By contrast, [Met5]enkephalin levels in the perfusates were increased by the combined administration of the two peptidase inhibitors but these levels were not further enhanced by noxious stimulation. Thus, spinal cord YGG appears to be formed under the influence of enkephalinase and to constitute a sensitive index of enkephalin release.     

Neural computations underlying the exertion of force: a model

We have developed a model that simulates possible mechanisms by which supraspinal neuronal signals coding forces could converge in the spinal cord and provide an ongoing integrated signal to the motoneuronal pools whose activation results in the exertion of force. The model consists of a three-layered neural network connected to a two-joint-six-muscle model of the arm. The network layers represent supraspinal populations, spinal cord interneurons, and motoneuronal pools. We propose an approach to train the network so that, after the synaptic connections between the layers are adjusted, the performance of the model is consistent with experimental data obtained on different organisms using different experimental paradigms: the stiffness characteristics of human arm; the structure of force fields generated by the stimulation of the frog's spinal cord; and a correlation between motor cortical activity and force exerted by monkey against an immovable object. The model predicts a specific pattern of connections between supraspinal populations coding forces and spinal cord interneurons: the weight of connection should be correlated with directional preference of interconnected units. Finally, our simulations demonstrate that the force generated by the sum of neural signals can be nearly equal to the vector sum of forces generated by each signal independently, in spite of the complex nonlinearities intervening between supraspinal commands and forces exerted by the arm in response to these commands.     

BDNF 和 IL-1α 免疫组织化学阳性细胞在商城肥鲵脊神经节中的表达

采用了组织学和免疫组织化学的方法对商城肥鲵的脊髓和脊神经节的石蜡切片进行了研究。结果显示,商城肥鲵的脊髓可分为灰质和白质;白质外有3层膜包围,由外向内依次是硬脊膜、蛛网膜和软脊膜。常规染色显示脊神经节位于脊神经后根,外包被膜,呈不规则的卵圆形,神经节内的细胞有两种,一种为节细胞,胞体圆形或者卵圆形,大小不等,根据胞体的大小又可分为大脊神经节细胞和小脊神经节细胞;另一种细胞叫做卫星细胞,包裹在脊神经节细胞的周围。BDNF和IL-1α一抗均显示脊神经节细胞呈阳性,卫星细胞呈阴性,前者大神经节细胞阳性明显强于小神经节细胞,后者两种神经节细胞的阳性强度无显著差异。     

Cerebellar learning of accurate predictive control for fast-reaching movements

Long conduction delays in the nervous system prevent the accurate control of movements by feedback control alone. We present a new, biologically plausible cerebellar model to study how fast arm movements can be executed in spite of these delays. To provide a realistic test-bed of the cerebellar neural model, we embed the cerebellar network in a simulated biological motor system comprising a spinal cord model and a six-muscle two-dimensional arm model. We argue that if the trajectory errors are detected at the spinal cord level, memory traces in the cerebellum can solve the temporal mismatch problem between efferent motor commands and delayed error signals. Moreover, learning is made stable by the inclusion of the cerebello-nucleo-olivary loop in the model. It is shown that the cerebellar network implements a nonlinear predictive regulator by learning part of the inverse dynamics of the plant and spinal circuit. After learning, fast accurate reaching movements can be generated. Received: 8 February 1999 /Accepted in revised form: 7 August 1999     

A method for removing the brain and spinal cord as one unit from adult mice and rats

To collect complete rodent spinal cord samples for histological analysis, researchers typically use a method that involves fixation of the carcass, followed by decapitation and removal of the vertebrae and the spinal cord. Researchers then decalcify, process and embed the spinal column in paraffin. When this method is used, the spinal cord retains its natural curvature, which may be undesirable to some investigators. The authors describe a methodology by which the entire spinal cord, with the brain attached, can be removed from a mouse or rat, set against a rigid support material and fixed perfectly straight. This allows for more precise sectioning and simplified histological analysis. Researchers can even create block preparations, each of which contains multiple spinal cord sections, so that they can compare anatomically matched sections. This procedure can also be used to obtain fresh spinal cord samples that are free of bone and can be frozen in optimal cutting temperature medium.     

Glioblastoma multiforme arising in the irradiated spinal cord of a rhesus monkey (Macaca mulatta)

Abstract: An adult female rhesus monkey that had received 44.0 Gy of cobalt 60 radiation to 8 cm of the cervical and upper thoracic spinal cord approximately 2.8 years postirradiation developed a sudden onset of self-mutilation and loss of function of the right arm followed progressively by loss of function of the left arm and terminally bilateral paresis of the legs. Histopathologic examination of the cervical spinal cord revealed a glioblastoma multiforme that extended from the cervical medullary junction to the sixth cervical vertebrae. Because of the infrequent occurrence of spontaneous neoplasia in rhesus monkeys and the location in the radiation field, the glioblastoma is believed to be radiation induced.     

犬脊髓损伤治疗动物模型

目的　建立犬脊髓损伤治疗动物模型 ,为实验研究提供直接的病例材料。方法　人工损伤犬脊髓 ,使用直流电场刺激使脊髓损伤恢复。结果　人工犬脊髓损伤模型建立 ,直流电场刺激治疗可恢复神经功能。结论直流电场刺激在不同时期对犬脊髓再生及功能恢复均有明显促进作用 ,能促进脊髓再生 ,使脊髓通路更快更完善的建立     

Flap surgery to cover olecranon pressure ulcers in spinal cord injury patients

In the quadriplegic patient, the periolecranon region is subjected to continuous and permanent mechanical shearing and pressure forces. As the sensation of this region is partially impaired secondary to the level of the spinal cord injury, this anatomical area is prone to develop bursitis and then a chronic open draining wound. This type of wound is refractory to conservative measures. Surgical closure of this functional area can represent a challenge to the plastic and reconstructive surgeon because not all of the surgical options available are suitable for spinal cord injury patients. Therefore, we describe our clinical experience, which consists of seven patients with traumatic complete quadriplegia treated between 1989 and 1998 (all patients were male) who presented with an open olecranon ulcer, septic bursitis, or aseptic bursitis, and who underwent surgical closure by direct closure, local arm fasciocutaneous flap, or cross-chest flap to cover the periolecranon soft-tissue defects. The follow-up period ranged from 3 months to 8 years (mean, 44 months). All types of flaps achieved wound closure without losing range of motion at the elbow; however, at 10 to 12 months after surgery, an olecranon pressure ulcer or septic bursitis recurred in three of seven patients. These three patients required surgical revision. The local fasciocutaneous rotational flap was found to be effective for closing periolecranon soft-tissue defects and can be reused in instances of recurrence. Patient education is essential to prevent re-ulceration in that functional area in the spinal cord injury patient.     

自噬通过BDNF/TrkB信号通路对脊髓损伤的保护作用

脊髓型颈椎病(cervical spondylotic myelopathy, CSM)是临床常见病、多发病,由该病引起的脊髓受损而产生的脊髓功能障碍是其最常见的临床特征。在脊髓损伤中,多种因素能通过自噬相关信号通路而激活自噬,适度的自噬可以对脊髓损伤起到神经保护作用,而增加细胞存活率、恢复和增加自噬通量可以改善损伤后的脊髓功能的恢复;在CSM脊髓损伤中,脑源性神经营养因子(brain derived neurotrophic factor, BDNF)与其受体原肌球蛋白受体激酶B(tropomyosin receptor kinase B, TrkB)及其相关通路是参与保护神经细胞的重要途径之一,细胞自噬在这一过程中起到了重要的调节作用。本文通过阐释自噬与BDNF/TrkB信号通路在CSM过程中的作用及其对脊髓损伤的保护机制,以期对基础研究及临床研究提供理论支持。