Chondroitinase ABC promotes functional recovery after spinal cord injury

The inability of axons to regenerate after a spinal cord injury in the adult mammalian central nervous system (CNS) can lead to permanent paralysis. At sites of CNS injury, a glial scar develops, containing extracellular matrix molecules including chondroitin sulphate proteoglycans (CSPGs). CSPGs are inhibitory to axon growth in vitro, and regenerating axons stop at CSPG-rich regions in vivo. Removing CSPG glycosaminoglycan (GAG) chains attenuates CSPG inhibitory activity. To test the functional effects of degrading chondroitin sulphate (CS)-GAG after spinal cord injury, we delivered chondroitinase ABC (ChABC) to the lesioned dorsal columns of adult rats. We show that intrathecal treatment with ChABC degraded CS-GAG at the injury site, upregulated a regeneration-associated protein in injured neurons, and promoted regeneration of both ascending sensory projections and descending corticospinal tract axons. ChABC treatment also restored post-synaptic activity below the lesion after electrical stimulation of corticospinal neurons, and promoted functional recovery of locomotor and proprioceptive behaviours. Our results demonstrate that CSPGs are important inhibitory molecules in vivo and suggest that their manipulation will be useful for treatment of human spinal injuries.     

基于图论算法的脊髓损伤后大脑皮层运动区神经元网络分析

 脊髓损伤(SCI)后大脑皮层运动区神经元的功能重组对机体功能康复的影响仍然不为人知。脊髓损伤前后,对一只在跑步机上直立行走的恒河猴的大脑皮层运动区神经元信号进行记录,利用不同神经元动作电位序列间的相关系数建立神经元网络图。为了研究神经元活动模式的变化与功能康复之间的联系,利用图论算法计算了神经元网络图的全局效能指标和神经元脆弱性指标。结果显示,不同时期神经元活动模式的显著变化意味着运动区神经元的功能重组(神经可塑性)与脊髓损伤后猴子的功能康复状态紧密相关,且这种神经功能重组对于猴子步行功能的康复起了非常重要的积极作用。     

基于DSP的临时膈肌刺激系统设计与实现

临床上各种常见膈肌功能不全的发生与膈肌的废用性萎缩有关,继而会出现呼吸困难甚至呼吸衰竭。为了在一定程度上预防膈肌萎缩,提出经颈内静脉途径电刺激膈神经的临时膈肌刺激方案,对该方案的参数计算方法进行了研究,给出了方案的硬件及软件设计。将21只家兔随机分为三组,病理结果表明与正常对照组相比较,脊髓离断控制通气组家兔的膈肌纤维存在明显萎缩,而电刺激膈神经组家兔膈肌纤维只有部分萎缩,证明该方案是一种有效的预防膈肌萎缩保护膈肌功能的方法,具有一定的临床意义。     

Morphological and electrophysiological evidence for regeneration of transected spinal cord fibers and restoration of motor functions in adult rats

The evoked potentials are regarded as an efficientindex to evaluate the functional status of a nervoussystem[1]. When stimulating the motor area of cerebralcortex with transcranial magnetic stimulation, elec-tronic signals can be obtained at the spinal co…     

Neuronal ensemble control of prosthetic devices by a human with tetraplegia

Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks. Here we show initial results for a tetraplegic human (MN) using a pilot NMP. Neuronal ensemble activity recorded through a 96-microelectrode array implanted in primary motor cortex demonstrated that intended hand motion modulates cortical spiking patterns three years after spinal cord injury. Decoders were created, providing a 'neural cursor' with which MN opened simulated e-mail and operated devices such as a television, even while conversing. Furthermore, MN used neural control to open and close a prosthetic hand, and perform rudimentary actions with a multi-jointed robotic arm. These early results suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis.     

神经营养因子联合治疗促进脊髓轴索再生的研究现状

神经营养因子（neurotrophic factors,NTFs）在急性脊髓损伤（spinal cord injury,SCI）后神经细胞的生长发育、保护和修复的过程中发挥重要作用。然而,单一的治疗尚不足以激活神经元内源性的再生程序;其次,再生抑制因子限制了NTFs对SCI后结构和功能恢复。因此,越来越多的学者选择以联合的方式探索NTFs对再生的促进作用。本文归纳了NTFs以联合的方式治疗轴索再生的基本原理和最新进展,旨在为联合治疗的进一步研究提供科学指导。     

Studies on repairing of hemisected thoracic spinal cord of adult rats by using a chitosan tube filled with alginate fibers

A chitosan tube filled with alginate fibers was implanted into the injured spinal cord of a rat for repairing the damaged tissue. Twelve months after the operation, the morphological observation demonstrated that this chitosan tube could induce regeneration of myelinated and non-myelinated axons and blood vessels. The Basso-Beattie-Bresnahan (BBB) behavioral evaluation confirmed that the implants played a key role in the long-term restoration of rats motor functions. It is a promising start in the treatment of the patients with the injury of the spinal cord.     

基因重组碱性成纤维细胞生长因子对大鼠脊髓损伤神经保护作用

目的 :探索碱性成纤维细胞生长因子 (bFGF)对大鼠脊髓损伤的神经保护作用 方法 :将吸入bFGF的胶原蛋白海绵或空白海绵贴敷于大鼠脊髓损伤处 ,术后 1、2、3周 ,对大鼠机能进行评分 ,并对大脑运动皮质进行电镜观察分析 结果 :术后 1、2、3周 ,bFGF组大鼠运动评分均明显优于对照组 (Ρ <0 .0 5) ,运动皮质电镜结果显示bFGF组线粒体、内质网轻度肿胀 ,神经毡结构正常 ,无明显胶质细胞增生 程度较对照组明显减轻 结论 :bFGF对大鼠脊髓受损神经纤维起源脑区—运动皮质的神经细胞具有明显的保护作用 ,进而使大鼠运动功能受损明显减轻     

Preliminary animal studies on observation of injured spinal cord with intraoperative ultrasound backscatter microscopy

Many studies have shown that strategies of nerve regeneration and cell-based transplantation are valid based on animal models of spinal cord injury (SCI).To apply these strategies and bridge spinal cord defects,the identification and precise localization of lesions during spinal cord surgery is necessary.The aim of the present experiment was to evaluate the capabilities of ultrasound backscatter microscopy (UBM) in identifying morphologic changes after SCI.After laminectomy,high-resolution ultrasound images of the spinal cord were obtained in one normal and seven spinal cord-injured adult Wistar rats using a UBM system with a 55-MHz center frequency scanner.Comparison between histoanatomic and UBM images was also performed.The results showed that UBM can identify cysts after the experimental SCI is removed in adult rats.In addition,the glial scar formed in secondary injury showed obvious hyperechoic speckle in the UBM image and correlated with the histoanatomic image.UBM has obvious clinical value in nerve regeneration and cell-based transplantation strategies in injured spinal cords.     

体育功能锻炼对截瘫患者康复影响及评价分析

目的:探讨体育功能锻炼对截瘫患者后期康复治疗的影响及康复评价.方法:76例在脊髓损伤后出现截瘫患者,进行体育功能锻炼的康复治疗,追踪记录,采用美国脊髓损伤学会(ASIA)脊髓损伤神经功能分类国际标准评价康复效果.结果:经统计,胸腰髓不完全损害者康复锻炼前后ASIA损伤评分运动、感觉评分均有显著意义(P<0.05).胸腰髓完全损伤者运动、感觉ASIA评分好转较明显(P<0.05).结论:体育功能锻炼能帮助截瘫患者后期恢复,显著改善和提高患者的综合功能.     

Motor neuron columnar fate imposed by sequential phases of Hox-c activity

The organization of neurons into columns is a prominent feature of central nervous system structure and function. In many regions of the central nervous system the grouping of neurons into columns links cell-body position to axonal trajectory, thus contributing to the establishment of topographic neural maps. This link is prominent in the developing spinal cord, where columnar sets of motor neurons innervate distinct targets in the periphery. We show here that sequential phases of Hox-c protein expression and activity control the columnar differentiation of spinal motor neurons. Hox expression in neural progenitors is established by graded fibroblast growth factor signalling and translated into a distinct motor neuron Hox pattern. Motor neuron columnar fate then emerges through cell autonomous repressor and activator functions of Hox proteins. Hox proteins also direct the expression of genes that establish motor topographic projections, thus implicating Hox proteins as critical determinants of spinal motor neuron identity and organization.     

Reducing excessive GABA-mediated tonic inhibition promotes functional recovery after stroke

Stroke is a leading cause of disability, but no pharmacological therapy is currently available for promoting recovery. The brain region adjacent to stroke damage-the peri-infarct zone-is critical for rehabilitation, as it shows heightened neuroplasticity, allowing sensorimotor functions to re-map from damaged areas. Thus, understanding the neuronal properties constraining this plasticity is important for the development of new treatments. Here we show that after a stroke in mice, tonic neuronal inhibition is increased in the peri-infarct zone. This increased tonic inhibition is mediated by extrasynaptic GABA(A) receptors and is caused by an impairment in GABA (γ-aminobutyric acid) transporter (GAT-3/GAT-4) function. To counteract the heightened inhibition, we administered in vivo a benzodiazepine inverse agonist specific for α5-subunit-containing extrasynaptic GABA(A) receptors at a delay after stroke. This treatment produced an early and sustained recovery of motor function. Genetically lowering the number of α5- or δ-subunit-containing GABA(A) receptors responsible for tonic inhibition also proved beneficial for recovery after stroke, consistent with the therapeutic potential of diminishing extrasynaptic GABA(A) receptor function. Together, our results identify new pharmacological targets and provide the rationale for a novel strategy to promote recovery after stroke and possibly other brain injuries.     

大白鼠坐骨神经再生轴突可塑性的研究——辣根过氧化物酶(HRP)示踪观察

用HRP逆行示踪法,对成年大白鼠两侧坐骨神经端端吻合术后,再生轴突可塑性作了研究。术后1—12月不同时间内,在吻合端左侧0.8cm处,再横断坐骨神经,放入HRP,存活2天,取材观察。结果表明:所有动物脊髓腰骶段两侧前角均出现HRP标记细胞。标记细胞数量随吻合术后时间增长而增加。左侧前角较右侧前角标记细胞多。说明受损的坐骨神经轴突能再生,各自进入对侧的坐骨神经,向脊髓方向延伸。但是,仅部分再生轴突能延伸过缝合处的组织痂。本实验提示再生轴突的可塑性,它受环境因素的影响。     

网球发球技术与腰背损伤关系的生物力学分析

为探讨网球发球技术与腰背损伤之间的关系,探寻导致腰背损伤的技术性原因,采用三维高速摄像法和图像解析法,以健康业余网球运动员为对照,对患有腰背部损伤业余网球运动员发球技术进行对比分析。结果表明搔背期末躯干扭转过大可能是造成业余网球运动员腰背损伤的直接原因,腰腹肌力量素质较差和抛球较偏是导致这一问题的主要技术性因素,并针对这些问题提出相应的解决办法,供教练员和业余运动员参考。     

Prevention of natural motoneurone cell death by dibutyryl cyclic GMP

Natural neuronal cell death is a well-described developmental phenomenon common to many nerve centres in a variety of animal species. Neuronal survival has been shown to depend on the presence and size of the available target tissue and it has been suggested that neuronal survival is dependent on successful competition for either a limited number of synaptic sites or a limited amount of trophic factor(s). In the lateral motor column of the lumbar spinal cord in the chick embryo, the period of axon elongation and innervation of the periphery has been shown to precede that of natural motoneurone cell death. While muscle contractile activity appears to regulate the extent of motoneurone death, to date the intracellular molecular events that initiate and regulate the developmental process of natural neuronal cell death or, more importantly, neuronal survival are unknown. Our earlier studies suggested that either contact or association between spinal cord processes and muscle cells during neuromuscular junction formation in vivo leads to an increase in cyclic GMP in whole spinal cord. We now show that treatment of chick embryos with the membrane-permeable cyclic GMP analogue, dibutyryl cyclic GMP during the period of natural motoneurone cell death prevents greater than 58% of natural motoneurone cell death in the lumbar lateral motor column.     

Kindling stimulation induces c-fos protein(s) in granule cells of the rat dentate gyrus

Alterations in neuronal gene expression have been proposed to account for permanent changes in brain function such as learning and memory. In particular, it has been suggested that protooncogenes such as c-fos may be rapidly induced in conditions that lead to neuronal plasticity and evoke permanent changes in the expression of effector genes. Concentrations of the c-fos proto-oncogene increase rapidly following depolarization-induced calcium influx in non-dividing neuronally differentiated PC 12 cells. Recently, the presence and induction of c-fos in the adult brain and spinal cord has been observed. Here we report that electrically-induced seizure activity, which leads to a permanent increase in the response of the brain to future seizures (kindling), rapidly and transiently increases c-fos protein-like immunoreactivity in the nuclei of granule cells in the rat dentate gyrus. These results suggest that c-fos protein is present within the nuclei of adult mammalian neurons, and could be involved in plastic changes in the nervous system associated with seizure activity.     

大鼠坐骨神经切断后经皮低频高强度电刺激相应脊髓节段中GAP-43表达的变化

目的探讨成年Wister大鼠在坐骨神经切断后GAP-43于相应脊髓节段前角运动神经元内的表达变化.方法选取健康成年雄性Wister大鼠60只,将坐骨神经切断,随机分为实验组和对照组,实验组给予经皮低频高强度电刺激,分别于术后1,2,4,8,12,16周处死,取其L4~L6脊髓,利用免疫组织化学技术检测GAP-43在相应脊髓节段中的表达变化,并利用影像分析系统进行统计学分析.结果对照组:1周时前角细胞胞体内GAP-43有明显表达,4周时达到高峰,5~8周时逐渐下调,9~16周时GAP-43在前角细胞胞体内中仍有少量表达,并呈弱阳性.实验组:1周时前角细胞胞体内GAP-43有明显表达,2周时达到高峰,且在4~16周时在神经元中仍有表达,并呈阳性.结论坐骨神经切断可导致成年大鼠相应脊髓节段中前角运动神经元GAP-43表达明显增加,可证明在周围神经损伤后神经元的再生能力增强,但时效很短.而给予低频高强度电刺激疗法后,GAP-43的表达在时长和量上都有明显增加.     

Nogo-A is a myelin-associated neurite outgrowth inhibitor and an antigen for monoclonal antibody IN-1

The capacity of the adult brain and spinal cord to repair lesions by axonal regeneration or compensatory fibre growth is extremely limited. A monoclonal antibody (IN-1) raised against NI-220/250, a myelin protein that is a potent inhibitor of neurite growth, promoted axonal regeneration and compensatory plasticity following lesions of the central nervous system (CNS) in adult rats. Here we report the cloning of nogo A, the rat complementary DNA encoding NI-220/250. The nogo gene encodes at least three major protein products (Nogo-A, -B and -C). Recombinant Nogo-A is recognized by monoclonal antibody IN-1, and it inhibits neurite outgrowth from dorsal root ganglia and spreading of 3T3 fibroblasts in an IN-1-sensitive manner. Antibodies against Nogo-A stain CNS myelin and oligodendrocytes and allow dorsal root ganglion neurites to grow on CNS myelin and into optic nerve explants. These data show that Nogo-A is a potent inhibitor of neurite growth and an IN-1 antigen produced by oligodendrocytes, and may allow the generation of new reagents to enhance CNS regeneration and plasticity.     

Identification of the Nogo inhibitor of axon regeneration as a Reticulon protein

Adult mammalian axon regeneration is generally successful in the peripheral nervous system (PNS) but is dismally poor in the central nervous system (CNS). However, many classes of CNS axons can extend for long distances in peripheral nerve grafts. A comparison of myelin from the CNS and the PNS has revealed that CNS white matter is selectively inhibitory for axonal outgrowth. Several components of CNS white matter, NI35, NI250(Nogo) and MAG, that have inhibitory activity for axon extension have been described. The IN-1 antibody, which recognizes NI35 and NI250(Nogo), allows moderate degrees of axonal regeneration and functional recovery after spinal cord injury. Here we identify Nogo as a member of the Reticulon family, Reticulon 4-A. Nogo is expressed by oligodendrocytes but not by Schwann cells, and associates primarily with the endoplasmic reticulum. A 66-residue lumenal/extracellular domain inhibits axonal extension and collapses dorsal root ganglion growth cones. In contrast to Nogo, Reticulon 1 and 3 are not expressed by oligodendrocytes, and the 66-residue lumenal/extracellular domains from Reticulon 1, 2 and 3 do not inhibit axonal regeneration. These data provide a molecular basis to assess the contribution of Nogo to the failure of axonal regeneration in the adult CNS.     

Direct control of paralysed muscles by cortical neurons

A potential treatment for paralysis resulting from spinal cord injury is to route control signals from the brain around the injury by artificial connections. Such signals could then control electrical stimulation of muscles, thereby restoring volitional movement to paralysed limbs. In previously separate experiments, activity of motor cortex neurons related to actual or imagined movements has been used to control computer cursors and robotic arms, and paralysed muscles have been activated by functional electrical stimulation. Here we show that Macaca nemestrina monkeys can directly control stimulation of muscles using the activity of neurons in the motor cortex, thereby restoring goal-directed movements to a transiently paralysed arm. Moreover, neurons could control functional stimulation equally well regardless of any previous association to movement, a finding that considerably expands the source of control signals for brain-machine interfaces. Monkeys learned to use these artificial connections from cortical cells to muscles to generate bidirectional wrist torques, and controlled multiple neuron-muscle pairs simultaneously. Such direct transforms from cortical activity to muscle stimulation could be implemented by autonomous electronic circuitry, creating a relatively natural neuroprosthesis. These results are the first demonstration that direct artificial connections between cortical cells and muscles can compensate for interrupted physiological pathways and restore volitional control of movement to paralysed limbs.