Alkylation of Chitosan as Nerve Conduit Biomaterial

IntroductionTrauma of the nervous system,which is one of themostimportant systems in the human body,oftenresults in permanent loss of function and greatdiscomfort for the patients.Study of peripheralnerve regeneration has not only relieved patientpain,but also provided insight into themechanisms of nerve development andregeneration. So both clinical medicine andfoundational life science benefit from the study ofperipheral nerve regeneration.　There has been a resurgence of interest in thedevel…     

Study on Braiding Parameters of a Biodegradable Nerve Regeneration Conduit with Regular Braided Structure

IntroductionIn clinical nerve repair, the situation is oftenencountered when the gap between the nerve stumps is toolarge topermit repair bydirect tensionless suture. Graftingwith a segment of autologous nerve is effective in suchsituation but has drawbacks such as donor site morbidityand incomplete recovery of function. With thedevelopment of tissue engineering involving medicascience, biology, material and engineeringscience, a nerveregenera…     

编织结构神经再生导管的编织工艺研究

在锭子编织机上，从节距、密度、厚度和孔隙率等神经再生导管的形态性能指标方面，探讨纱线的线密度、齿轮比以及编织机的锭子数等主要参数对PGLA神经再生导管形态性能的影响规律，探讨了神经再生导管的编织规律和较佳的编织工艺范围。     

Neural Stem Cell Affinity of Chitosan and Feasibility of Chitosan-Based Porous Conduits as Scaffolds for Nerve Tissue Engineering

Introduction Neural stem cells (NSCs) are known to have both self- proliferation potential and multiple differentiation po- tential[1]. Previous studies have shown that NSCs can differentiate into various cell types such as neurons, as- trocytes, oligoden…     

促进周围神经再生的药物研究进展

周围神经损伤是目前临床上常见的创伤并发症.促进周围神经损伤后的再生,恢复其功能已日益成为研究的热点.近年来,不少学者做了药物促进周围神经再生的研究并取得了一定效果.本文将近年来临床与实验研究中常用促进周围神经再生的药物做一综述.     

脊髓背根神经节切除模型——周围神经趋化性再生定量研究模型的建立

为了建立脊髓背根神经节（dorsal root ganglion,DRG）切除模型,选择性地使感觉神经纤维溃变而保持运动神经纤维的正常功能,从而为周围神经趋化性再生的定量评价提供有效的研究方法。将雄性SD大鼠20只,随机分为两组,每组10只动物。大体解剖组：解剖大鼠坐骨神经的神经根组成及DRG的位置。DRG切除组：切除支配大鼠坐骨神经的每个神经根的DRG。观察大鼠DRG切除后步态变化及足部溃疡情况。切除后3周,取双侧坐骨神经、胫神经、腓神经及腓肠神经行髓鞘染色,观察各神经中感觉神经纤维溃变情况;行美兰复红染色,计算机图像分析,运动神经纤维计数。发现大鼠坐骨神经由L4、L5、L6神经干组成,DRG位于腹、背侧根汇合处近心端1mm处。DRG切除术后,大鼠步态失去协调性,但展趾宽度无明显改变。DRG切除后3周,髓鞘染色显示腓肠神经中有髓神经纤维髓鞘完全溃变,坐骨神经、胫神经、腓神经中部分有髓神经纤维发生溃变。美兰复红染色、计算机图像分析计数显示坐骨神经及三个主要分支内,有髓运动神经纤维分别占其总数的58．4％、54．6％、45．4％、0。说明DRG切除模型,可以有效区分感觉和运动神经纤维,能够较好地定量评价周围神经趋化性再生的效果。通过比较不同桥接材料和不同修复方法的错接率,从而定量评价各修复材料和方法的趋化性再生效果。     

雪旺细胞对于周围神经再生的功能与作用

通过查阅近年来国内外大量文献,结果显示雪旺细胞的生物学特性决定了其是周围神经再生过程中的重要种子细胞,并正成为周围神经损伤修复领域中的研究热点.     

不同断面神经束组吻合对周围神经再生影响的实验研究

目的 观察不同断面神经束组吻合对大鼠坐骨神经再生的影响。方法 将32只大鼠随机分为4组,各组大鼠均切断双侧坐骨神经后立即在显微镜下左侧施行不同断面神经束组吻合,右侧施行同一断面神经束组吻合。分别于第,2,4,6,8周检测两侧坐骨神经运动诱发电位的潜伏期和波幅,有髓神经纤维数。结果 各指标经统计学处理,术后第2周,实验侧和对照侧之间差异无统计学意义。结论 不同断面神经束组吻合在神经恢复后期有加速神经再生作用,优于同一断面神经束组吻合。     

Fiber-Based Chitosan Tubular Scaffolds for Soft Tissue Engineering： Fabrication and in Vitro Evaluation

Porous, two-ply tubular chitosan conduits for guided tissue regeneration were fabricated by combining the textile technique （inner layer） with the thermally induced phase separation process （outer layer）. A hollow chitosan tube was prepared using an industrial warp knitting process with chitosan yarns. Then, an appropriate diameter mandrel was inserted into the pre-fabricated tube. The tube and the mandrel were dipped into the chitosan solution together, taken out, and freeze-dried. After being neutralized in alkaline solution and dried at room temperature, the mandrel was removed to create the chitosan tubular scaffold. Scanning electron micrographs show that the resulting tubes have a biphasic wall structure, with a fibrous inner layer and a semipermeable outer layer. The swelling properties and the mechanical strength before and after in vitro degradation were investigated. The biocompatibility of the scaffolds was also investigated by co-culturing neuroblastoma cells （N2A, mouse） with the scaffolds. The results suggest that these chitosan tubular scaffolds are useful for the regeneration of tissues requiring a tubular scaffold.     

Feasibility of Using Chitosan in Nerve Repair

IntroductionChitin,themajorpolysaccharideininsectexoskeletonsandcrustaceanshells,hasβ(1-4)-linkedN-acetylglucosaminerepeatunitsandisthesecondmostabundantformofpolymerizedcarbonfoundinnature[1].Chitosan,thefullyorpartiallyN-deacetyledformofchitin,isacationicpolysaccharidecomposedofglucosamineandN-acetylglucosamineresidueswitha1,4-β-linkage.Ithasastructuresimilartoglycosaminoglycans,whicharethecomponentsofanextracellularmatrixandisbiocompatible[2].Duetoitspositivesurfacechargeandbiocompatibi…     

可促进神经再生的胶原蛋白中空湿法纺丝成形研究

对牛胶原蛋白的可纺性厦湿法中空成形进行了研究，探讨了胶原蛋白不同的制备工艺参数如pH值、温度、离子强度等对胶原蛋白可纺性的影响，并着重讨论了纺丝速度、填充液压力、致孔剂含量等纺丝工艺参数与胶原中空纤维膜性能厦结构的关系。体外细胞实验的结果表明：该胶原蛋白对神经细胞的生长具有促进作用。     

Fabrication and Characterization of Chitosan Nerve Conduits with Microtubular Architectures

Porous multi-channel chitosan conduits were fabricated using a novel phase-separation technique with an axial temperature gradient. First, porous chitosan tubes were made with a mold that was composed of two concentric polytetrafiuoroethylene tubes. Then 1%-3% （w/v） chitosan solution was injected into the chitosan tube while the two ends of the tube were closed with steel rods. Then the outside of the tube was wrapped with a layer of thermal insulating material to reduce the heat transfer through the outside, and the tubes were placed in a freezer. The resulting phase separation then occurred in the presence of an axial temperature gradient. The porosity, microtubule diameter, and orientation were controlled by adjusting the polymer concentration and temperature gradient. After the preparation course, no poisonous substances remained on the conduits. The mechanical properties, swelling, and biodegradability of the chitosan conduits were investigated, and a scanning electron microscope was used to observe the tubular morphology and growth of neuroblastoma cells （N2A, mouse） in the conduits. The results demonstrate that the multi-channel chitosan conduits have suitable mechanical strength, swelling, degradation properties, and nerve cell affinity, so they hold promise for use as neural tissue engineering scaffolds.     

小鼠视神经再生研究动物模型的建立

目的总结制作小鼠视神经完全截断性动物模型作为视神经再生研究的经验和体会。方法将雄性Bcl-2高表达转基因小鼠(Bcl-2 transgenic mice)和受GFAP启动子控制表达疱疹病毒-胸苷激酶转基因雌性小鼠(GFAP-TK)交配产生的4只8~12周成年小鼠(20~30g),Bcl-2/GFAP-TK双转基因小鼠作为实验组,同周龄4只Bcl-2转基因小鼠作为对照组。其中Bcl-2/GFAP-TK双转基因小鼠皮下植入缓释泵,连续7d释放更昔洛韦(GCV)100mg.kg-1.d-1以选择性地去除视神经损伤后激活的星形胶质细胞。更昔洛韦缓释泵植入术后2d在两组动物中制作右侧单眼标准完全性视神经钳夹损伤模型,视神经钳夹10d后获取组织标本。采用免疫荧光染色特异性检测再生轴突纤维并进行定量分析;结合罗丹明的霍乱毒素B亚单位(CTB-R)或增强表达绿色荧光蛋白的复制缺陷型腺相关病毒(AAV-EGFP)用作顺行性标记物以显示再生轴突是否到达大脑靶器官。结果在Bcl-2/GFAP-TK双转基因小鼠中存在免疫荧光阳性的再生视神经轴突,再生轴突计数为71.99±24.04,并可见生长锥(growth cone)样结构,但是再生轴突纤维未能延伸达到大脑靶器官。在对照组Bcl-2转基因小鼠中未见明显再生迹象。结论小鼠视神经完全截断性动物模型可用于视神经病变的再生研究。     

穴位针刺对面神经再生影响的动物模型制作

介绍了穴位电针刺激对面神经再生影响的实验研究动物模型的制作,包括动物选择,穴位选择及其定位,针刺方法及治疗参数等方面,所造之模型使实验进行顺利,治疗后针刺组动物面神经的再生质量明显优于非针刺组,显示了其实用性和科学性。     

电刺激小脑顶核对大鼠心肌梗死后心脏神经再生的影响

探讨预先电刺激小脑顶核(FNS)对大鼠心肌梗死(MI)后心脏神经再生的干预作用。将90只Wistar大鼠随机分为:①MI组,结扎左冠状动脉前降支(LAD);②预先电刺激小脑顶核后再予以LAD结扎组(FNS MI组);③毁损小脑顶核后电刺激该部位,再行LAD结扎组(FNL FNS MI组)。各组又分MI后1,7,21d3个时间点。另设假手术组(Sham组)。应用免疫组织化学方法显示心脏组织胆碱乙酰转移酶(CHAT)和酪氨酸羟化酶(TH)。检测各时间点梗死区与非梗死区TH、CHAT阳性神经纤维分布密度,MI组与Sham组相比显著减少(P<0.01);FNS MI组较MI组显著增多(P<0.05);FNL FNS MI组与MI组比较无显著性差异(P>0.05)。因此,电刺激小脑顶核可增加梗死区和非梗死区心肌组织TH、CHAT染色阳性神经纤维密度,促进MI后心脏神经纤维再生。     

Radial Compressive Property of Nerve Regeneration Conduit with PGLA Biodegradable Fibers

Radial compressive property greatly influences nerve regeneration and functional recovery. In this study,four types of braided bioabsorbable nerve regeneration conduits made from poly(glycolide-co-L-lactide)(PGLA) were produced. The aim is to test the radial compressive force and elastic recovery ratio of nerve regeneration conduits. The results indicated that radial compressive force was closely related to the inner diameter and length of tubes and elastic recovery ratio was nearly unaffected by these two factors.     

壳聚糖微珠作为亲和层析载体的制备及其用于分离牛凝血酶的研究

在壳聚糖微珠的制备过程中壳聚糖的浓度，交联剂等因素直接影响壳聚糖微珠的质量和性能。用于牛凝血酶亲和层析载体的壳聚糖微珠制备，以壳聚糖浓度为1．5％，交联剂浓度较大时比较适宜，壳聚糖微珠经过环氧氯丙烷活化并与肝素耦联制成亲和层析剂分离和纯化牛凝血酶，每克干物质可吸附5800IU凝血酶，进一步纯化回收率可达到84％。未经活化与肝素耦联的壳聚糖微珠对牛凝血酶则无特异吸附作用。     

花背蟾蜍蝌蚪视神经再生与角膜诱导间关系的研究

以花背蟾蜍（Bufo raddei Srauch)后肢芽期蝌蚪为材料,切断其左眼视神经并进行角膜移植,在角膜诱导的不同时期取眼球固定,用环氧树脂Epon812包埋,制成兰薄切片,用次甲蓝、天青Ⅱ、硼砂染色后,在光学显微镜下观察切断视神经后视网膜的退化过程及在视神经再生的情况下视网膜诱导皮肤移植片转化为角膜的作用。结果表明,切断视神经,引起视网膜逐渐退化,移植的皮肤片与正常的皮肤其本相似;在分断的视神经发生再生并恢复其正常的生理功能的情况下,退化的视网膜逐渐恢复,同时被移植的皮肤片也出现表皮的去分化及表皮变薄等被诱导为角膜的过程,并对视神经的完整性与其诱导皮肤移植片转化为角膜之间的可能关系进行了讨论。     

鱼类视神经损伤和再生的研究

综述了鱼类视网膜－顶盖系统的研究概况，包括视网膜、视神经和顶盖的组织结构特点；同时介绍了损伤视神经引起的视网膜神经节细胞的变化及其跨神经元的影响；最后综述了视神经再生与神经传入活性、相邻神经纤维间的相互作用及靶区选择的关系等方面的研究进展