壳聚糖导管材料的制备及力学性能研究

目的壳聚糖在组织工程血管支架、神经修复导管等方面虽有潜在的广泛用途,但体内降解慢,本实验研究壳聚糖导管在满足基本力学性能要求下尽量降低管壁的厚度,以缩短降解时间。方法在初始溶液中加入聚乙二醇、甘油,通过浸渍-沥滤法制备壳聚糖管状材料,研究不同的成型工艺参数对壳聚糖导管力学性能的影响。结果在初始溶液中加入适量的甘油有利于提高壳聚糖导管的断裂应力和断裂伸长率,但其杨氏模量无显著变化;2%的壳聚糖初始溶液较2.5%所制备的导管的断裂应力、断裂应变和杨氏模量高;制备过程浸入-干燥的次数为2次的较3次制备出的导管的断裂应力、断裂应变和杨氏模量高。结论初始溶液中甘油、壳聚糖浓度以及重复次数都会影响导管的力学性能,优化成型工艺能在满足基本力学性能要求下降低管壁的厚度以达到最佳效果。     

3D-SC人工皮肤材料组织相容性的实验研究

目的观察实验材料3D-SC人工皮肤的组织相容性。方法将阴性对照材料DERMMATRIXTM和实验材料3D-SC组织工程材料分别植入SD大鼠背部皮下组织中,分别于1、4、12周在光镜下观察组织学反应。结果植入1周,实验组和对照组的纤维包膜厚度相比差异有显著统计学意义（P〈0.01）;阴性对照材料和3D-SC组织工程材料炎细胞浸润以淋巴细胞和中性粒细胞为主,个别对照材料发现少量异物巨细胞,实验材料未见异物巨细胞;两种材料的淋巴细胞、中性粒细胞数量相当（P〉0.05）。植入4周,对照组的纤维厚度增长显著（P〈0.01）,与对照组包膜厚度相当（P〉0.05）;实验组与对照组中淋巴细胞、中性粒细胞及异物巨细胞数量相当（P〉0.05）;与植入1周相比,实验组的淋巴细胞数量减少明显（P〈0.01）,而对照组材料变化不明显（P〉0.05）;对照组的中性粒细胞数量减少明显（P〈0.05）,实验组的中性粒细胞数量变化不大（P〉0.05）;两种材料均出现少量异物巨细胞,差别不大（P〉0.05）。植入12周,对照组和实验组的包膜厚度相当（P〉0.05）,各种炎细胞浸润显著减少,表现相当（P〉0.05）;两种材料未见异物巨细胞;与植入1周相比,实验组的中性粒细胞数量减少显著（P〈0.05）。结论3D-SC组织工程材料具有较好的组织相容性。     

基于天然高分子材料的组织工程化皮肤支架材料

支架材料在组织工程中具有调控所种植细胞的组织化、细胞增殖和新组织形成的重要作用。文章就目前常用于组织工程化皮肤支架材料的天然高分子材料的分类、研究现状及前沿动态作了概述,对组织工程化皮肤支架材料目前存在的问题、研究的重点和热点作了归纳分析,并对其发展趋势进行了展望,预测了组织工程化皮肤的理想支架材料。     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述。     

骨组织工程中支架材料的研究进展

骨组织工程的支架材料首先应具有支持结构,其次具有组织相容和引导成骨的作用。目前骨组织工程的支架材料种类很多、来源不同、性能各异。本文综述了骨组织工程中支架材料的最新研究进展和前景。     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述.     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述.     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述.     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述.     

尿道修复材料的研究及应用进展

尿道修复材料是尿道修复重建成败的关键,将尿道的修复材料分为自体组织材料、人工合成材料及组织工程化材料,从实验室和临床2方面对尿道修复材料的研究及应用进展进行综述.     

Effect of Antibodies to Nerve Growth Factor and Serum Albumin on the Development and Behavior of Mice

We studied physical development, behavioral characteristics, and learning capacity in the offspring of mice immunized with nerve growth factor and bovine serum albumin. High titer of antibodies to these factors in the blood of pregnant females determines high levels of these antibodies in the blood of their pups. These changes modulate physical development, behavior, and learning capacity of rat pups. The effects of these antibodies differed in the strength and directionality. Antibodies to nerve growth factor more markedly retarded physical development, reduced learning capacity, and considerably increased pain thresholds in animals.     

Targeting Nerve Growth Factor in Pain

Chronic pain presents a huge economic and social burden, with existing treatments largely unable to satisfy medical needs. Recently, studies have shown that nerve growth factor (NGF) is a major mediator of inflammatory and neuropathic pain, providing a new therapeutic target. Although originally discovered as a trophic factor for sympathetic and sensory neurons during development, it now appears that in adults, levels of NGF are elevated in many acute and chronic pain conditions. Furthermore, preclinical animal models of inflammatory and neuropathic pain also show increased NGF levels, while the sequestration of NGF alleviates the associated hyperalgesia. The molecular mechanisms involved are being elucidated. This review briefly examines pain signaling pathways and describes currently available analgesics. It then investigates the approaches taken in targeting NGF-mediated pain. Current options being explored include the development of humanized monoclonal antibodies to NGF or its tyrosine kinase receptor TrkA (also known as neurotrophic tyrosine kinase receptor, type 1 [NTRK1]), and the sequestration of NGF using TrkA domain 5 (TrkAd5), a soluble receptor protein that binds NGF with picomolar affinity. Administration of either antibodies or TrkAd5 has been shown to be effective in a number of preclinical models of pain, including cystitis, osteoarthritis, UV irradiation (sunburn), and skeletal bone pain due to fracture or cancer. Other possible future therapies examined in this review include small-molecule TrkA antagonists, which target either the extracellular NGF binding domain of TrkA or its intracellular tyrosine kinase domain.     

Insulin-Like Growth Factor I Promotes Nerve Regeneration: An Experimental Study on Rat Sciatic Nerve

Abstract

Growth without growth hormone (GH) is often observed in the setup of obesity; however, the missing link between adipocytes and linear growth was until now not identified. 3T3L1 cells were induced to differentiate into adipocytes and their conditioned medium (CM) (adipocytes CM, CMA) was added to metatarsals bone culture and compared to CM derived from undifferentiated cells. CMA significantly increased metatarsals bone elongation. Adipogenic differentiation increased the expression of growth and differentiation factor (GDF)-5, also found to be secreted into the CMA. GDF-5 significantly increased metatarsal length in culture; treatment of the CMA with anti-GDF-5 antibody significantly reduced the stimulatory effect on bone length. The presence of GDF-5 receptor (bone morphogenetic protein receptor; BMPR1) in metatarsal bone was confirmed by immunohistochemistry. Animal studies in rodents subjected to food restriction followed by re-feeding showed an increase in GDF-5 serum levels concomitant with nutritional induced catch up growth. These results show that adipocytes may stimulate bone growth and suggest an additional explanation to the growth without GH phenomenon.     

Heparin-Binding-Affinity-Based Delivery Systems Releasing Nerve Growth Factor Enhance Sciatic Nerve Regeneration

The controlled delivery of nerve growth factor (NGF) to the peripheral nervous system has been shown to enhance nerve regeneration following injury, although the effect of release rate has not been previously studied with an affinity-based delivery system (DS). The goal of this research was to determine if the binding site affinity of the DS affected nerve regeneration in vivo using nerve guidance conduits (NGCs) in a 13-mm rat sciatic nerve defect. These DSs consisted of bi-domain peptides that varied in heparin-binding affinity, heparin and NGF, which binds to heparin with moderate affinity. Eight experimental groups were evaluated consisting of NGF with DS, control groups excluding one or more components of the DS within silicone conduits and nerve isografts. Nerves were harvested 6 weeks after treatment for analysis by histomorphometry. These DSs with NGF resulted in a higher frequency of nerve regeneration compared to control groups and were similar to the nerve isograft group in measures of nerve fiber density and percent neural tissue, but not in total nerve fiber count. In addition, these DSs with NGF contained a significantly greater percentage of larger diameter nerve fibers, suggesting more mature regenerating nerve content. While there were no differences in nerve regeneration due to varying peptide affinity with these DSs, their use with NGF enhanced peripheral nerve regeneration through a NGC across a critical nerve gap.     

恒流电刺激下神经纤维的非线性行为

生命系统中存在着丰富的非线性现象。我们对于恒流电刺激下的单根神经纤维兴奋性进行了计算机仿真，观察到了非线性振荡现象，得到了膜电位稳定态和周期态与刺激电流强度的关系，以及周期振荡频率与刺激强度间的关系。     

神经生长因子偶联物对老年性痴呆动物模型的保护作用

目的　探讨神经生长因子偶联物 (NGF -Tf)对老年性痴呆 (AD)大鼠的影响 .方法　以手术切断大鼠双侧隔 -海马胆碱能通路的方法建立AD动物模型 ,每天从大鼠尾静脉注射NGF -Tf .通过水迷路试验观察大鼠的记忆和方向辨别能力 ;对海马和隔区行神经组织学检查 ;应用酶组织化学技术显示相应区域的ChAT ,采用计算机病理图像分析系统测定酶活性以判断其胆碱能功能状态 .结果　水迷路试验中 ,NGF -Tf组在 10s内抵达平台的正确反应平均数提高 (p <0 .0 5 ) .光镜下 ,NGF -Tf组隔区仅见轻微萎缩性改变 ,而模型组隔区萎缩性改变较明显 ,表现为神经元数目明显减少 ,细胞轮廓不清 ,有胶质细胞增生 ;正常对照组、NGF -Tf组和模型组的海马区未见明显病理性改变 .ChAT染色统计结果显示 ,正常对照组、NGF -Tf组大鼠的海马区及隔区IOD值与模型组比较 ,均有显著性差异 (p <0 .0 1) .结论　NGF -Tf能穿透血脑屏障 ,有效防止模拟AD病变的大鼠的基底前脑胆碱能神经元的变性和死亡 ,改善其记忆和方向辨别能力 ,促进其胆碱能神经元的功能恢复     

Expression of Nerve Growth Factor and its Receptor in Distracted Tibial Nerve after Limb Lengthening

Despite many experimental and clinical studies conducted on distraction osteogenesis (DO) in the past decade, changes in the surrounding tissues that occur after the procedure remains poorly understood. To study the biochemical changes of recovery in nerve tissues upon DO‐induced nerve injury, we prepared a rabbit model of tibia lengthening to observe the expression pattern of nerve growth factor (NGF) and low‐affinity NGF receptor (p75NGFR) in the distracted tibial nerve. The distracted tibial nerve was harvested at various time points during the consolidation period of new bone formation and immunohistochemical staining was performed to detect the expression of NGF and p75NGFR. The expression levels of NGF and p75NGFR were found to be different at various times after DO. The changes in expression of these two cellular factors show similar tendencies with significantly elevated expression in Schwann cells at 7 and 14 days after distraction, but low or undetectable levels of expression at 0, 28, and 56 days. These results suggest that NGF and p75NGFR may play important roles in the adaptive process of the distracted nerve. NGF and p75NGFR are autocrine growth factors present in the distracted nerve during the early consolidation period. NGF interacts with p75NGFR to promote damage repair and reconstruction of nerves. Together, this study furthers the understanding of the relative mechanisms of nerve repair, as well as provides a further basis for the clinical application of neurotrophins. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.     

神经生长因子偶联物对老年性痴呆动物模型的保护作用

目的探讨神经生长因子偶联物(NGF-Tf)对老年性痴呆(AD)大鼠的影响.方法以手术切断大鼠双侧隔-海马胆碱能通路的方法建立AD动物模型,每天从大鼠尾静脉注射NGF-Tf.通过水迷路试验观察大鼠的记忆和方向辨别能力;对海马和隔区行神经组织学检查;应用酶组织化学技术显示相应区域的ChAT,采用计算机病理图像分析系统测定酶活性以判断其胆碱能功能状态.结果水迷路试验中,NGF-Tf组在10s内抵达平台的正确反应平均数提高(p<0.05).光镜下,NGF-Tf组隔区仅见轻微萎缩性改变,而模型组隔区萎缩性改变较明显,表现为神经元数目明显减少,细胞轮廓不清,有胶质细胞增生;正常对照组、NGF-Tf组和模型组的海马区未见明显病理性改变.ChAT染色统计结果显示,正常对照组、NGF-Tf组大鼠的海马区及隔区IOD值与模型组比较,均有显著性差异(p<0.01).结论 NGF-Tf能穿透血脑屏障,有效防止模拟AD病变的大鼠的基底前脑胆碱能神经元的变性和死亡,改善其记忆和方向辨别能力,促进其胆碱能神经元的功能恢复.     

NGF与CNTF对大鼠坐骨神经轴突再生的诱导趋化作用研究

目的：探讨神经生长因子（NGF）与睫状神经营养因子（CNTF）对大鼠坐骨神经轴突再生诱导趋化作用.方法：利用自行研制的梭形双通道乳胶管桥接大鼠坐骨神经10mm缺损段,并将50只SD大鼠随机分为5组.A组乳胶管的两支管内不加入任何物质;B组两支管内均加入医用几丁糖凝胶;C组两支管内注入医用几丁糖凝胶后,分别加NGF和CNTF;D组两支管内注入医用几丁糖凝胶后,分别加NGF和NGF＋CNTF;E组两支管内注入医用几丁糖凝胶后,分别加CNTF和NGF＋CNTF.术后3、4周观察两支管内神经定向趋化情况,并对术后4周再生神经行HE染色和超微结构观察.结果：A组和B组两支管内神经再生速度及超微结构无明显差异;C组术后3周再生神经优先向CNTF侧趋化,术后4周CNTF侧神经再生成功率和超微结构优于NGF侧（P＜0.05）;D组和E组,再生神经向NGF＋CNTF侧趋化,且再生成功率、HE染色和超微结构观察均显示,NGF＋CNTF侧再生神经的速度及质量优于对照侧.结论：CNTF较NGF对大鼠坐骨神经有较强的诱导趋化作用,而且两者间存在明显的协同作用.