坐骨神经横断伤后远侧段组织的形态学及相关因子表达变化

目的:通过制备GFP小鼠和B6小鼠坐骨神经横断伤模型,应用免疫组化技术以及RealTime-PCR技术观察和分析周围神经损伤后远侧段组织的形态学及相关因子表达变化。方法:制备GFP小鼠坐骨神经横断伤模型,应用免疫组化技术分别染色S100蛋白以显示施万细胞,染色NF蛋白以显示轴突;结合GFP小鼠的自发荧光以及Hoechst核染观察横断伤后不同时间点远侧段组织的形态学变化。制备B6小鼠坐骨神经横断伤模型,应用RealTime-PCR技术检测横断伤后远侧段组织中相关营养因子BDNF、NGF、CNTF及抗凋亡因子Bcl-2 mRNA的表达变化。结果:坐骨神经横断伤后,远侧段施万细胞S100蛋白的表达第7天时达到高峰,第14天时下降,形成狭长细胞索带;第21～28天时仅少数细胞S100蛋白阳性。远侧段NF免疫组化产物于横断伤后第7天时断裂呈碎片状,第28天时碎片亦基本消失不见。远侧段非特异核染数目随损伤时间延长而增加。同时,在远侧段整个溃变过程中,神经基膜管结构仍然可见。坐骨神经横断伤后,BDNF mRNA表达第1～3周内逐渐上调,其中第3周时达到高峰(P<0.01),第4周时下降到与正常值相比无统计学意义的水平。NGF mRNA表达第1周时达到高峰(P<0.01),第2周时比第1周有小幅下降,但仍然具有统计学意义(P<0.01),第二周以后下降到与正常值相似的水平。CNTF mRNA表达则在损伤后第1周时下降了35%,第2周时继续下降到正常水平的42.7%,其下降均具有统计学意义(P<0.01),第3周时有所回升,第4周时下降到低点。Bcl-2 mRNA表达在损伤后第1周时下降,第2、3周时上升,第3周时达到高峰,并且上升具有统计学意义(P<0.01)。结论:坐骨神经横断伤后4周,远侧段神经组织中神经基膜管结构仍然存在。神经营养因子BDNF、NGF、CNTF mRNA的表达时相不同,提示其表达调控机制不同。Bcl-2 mRNA表达变化与施万细胞凋亡相关。     

应用X线照射后的Balb/c小鼠制备白血病模型的方法学研究

目的:探索用SPF级Balb/c小鼠经X线照射后,尾静脉注射转染GFP及NeoR基因的K562细胞株以制备白血病模型的方法。方法:实验组小鼠分别经X线照射2Gy和3Gy,24小时后取对数生长期的K562(GFP+/Neo+)细胞尾静脉注射2×106个/只。对照组不予特殊处理。结果:实验组在接种5-7天时发病,分别于30、24天内全部死亡;生存天数显著短于对照组(P<0.01)。体重较对照组显著下降(P<0.05)。小鼠的白血病发病率为100%,无自发缓解。随照射剂量的增加,小鼠的存活时间缩短,且外周血及骨髓中白血病细胞所占比例增加。流式细胞仪测定及PCR方法也证实了GFP+细胞和NeoR基因在外周血、骨髓、肝、脾中的存在。结论:Balb/c小鼠经照射后从尾静脉注射K562细胞株可以获得白血病模型。     

Allogeneic administration of fetal membrane-derived mesenchymal stem cells attenuates acute myocarditis in rats

We reported previously that the autologous administration of bone marrow-derived mesenchymal stem cells (BM-MSC) significantly attenuated myocardial dysfunction and injury in a rat model of acute myocarditis by stimulating angiogenesis and reducing inflammation. Because BM aspiration procedures are invasive and can yield low numbers of MSC after processing, we focused on fetal membranes (FMs) as an alternative source of MSC to provide a large number of cells. We investigated whether the allogeneic administration of FM-derived MSC (FM-MSC) attenuates myocardial injury and dysfunction in a rat myocarditis model. Experimental autoimmune myocarditis (EAM) was induced in male Lewis rats by injecting porcine cardiac myosin. Allogeneic FM-MSC obtained from major histocompatibility complex-mismatched ACI rats (5 × 10⁵ cells/animal) were injected intravenously into Lewis rats one week after myosin administration. At day 21, severe cardiac inflammation and deterioration of cardiac function were observed. The allogeneic administration of FM-MSC significantly attenuated inflammatory cell infiltration and monocyte chemoattractant protein 1 expression in the myocardium and improved cardiac function. In a T-lymphocyte proliferation assay, the proliferative response of splenic T lymphocytes was significantly lower in cells obtained from FM-MSC-treated EAM rats that reacted to myosin than in cells obtained from vehicle-treated rats with EAM. T-lymphocyte activation was significantly reduced by coculture with FM-MSC. The allogeneic administration of FM-MSC attenuated myocardial dysfunction and inflammation, and the host cell-mediated immune response was attenuated in a rat model of acute myocarditis. These results suggest that allogeneic administration of FM-MSC might provide a new therapeutic strategy for the treatment of acute myocarditis.     

灰树花多糖对糖尿病小鼠的降血糖作用

目的：观察灰树花多糖（GFP）对糖尿病小鼠（DM）的血糖调节作用。方法：将四氧嘧啶按180mg／kgb．wt．剂量腹腔内1次性注射制作糖尿病小鼠模型。实验组分别按750、250、125rng／kgb．wt．三个剂量每天灌服GFP,正常对照组和实验对照组每日灌服相应体积的水,实验周期均为40d。尾静脉采血测小鼠血糖值及糖耐量实验。结果：喂养40d后,250mg／kg．b．wt．剂量组与实验对照组比较,血糖水平和血糖曲线下面积均明显降低（P〈0.05）,750和125mg／kgb．wt．剂量组与实验对照组比较无明显降低（P〉0.05）。结论：灰树花多糖具有降低实验性糖尿病小鼠血糖的作用。     

Quantitative GFP fluorescence as an indicator of arsenite developmental toxicity in mosaic heat shock protein 70 transgenic zebrafish

In transgenic zebrafish (Danio rerio), green fluorescent protein (GFP) is a promising marker for environmental pollutants. In using GFP, one of the obstacles which we faced was how to compare toxicity among different toxicants or among a specific toxicant in different model species with the intensity of GFP expression. Using a fluorescence detection method, we first validated our method for estimating the amount of GFP fluorescence present in transgenic fish, which we used as an indicator of developmental toxicity caused by the well-known toxicant, arsenite. To this end, we developed mosaic transgenic zebrafish with the human heat shock response element (HSE) fused to the enhanced GFP (EGFP) reporter gene to indicate exposure to arsenite. We confirmed that EGFP expression sites correlate with gross morphological disruption caused by arsenite exposure. Arsenite (300.0 microM) caused stronger EGFP fluorescence intensity and quantity than 50.0 microM and 10.0 microM arsenite in our transgenic zebrafish. Furthermore, arsenite-induced apoptosis was demonstrated by TUNEL assay. Apoptosis was inhibited by the antioxidant, N-acetyl-cystein (NAC) in this transgenic zebrafish. The distribution of TUNEL-positive cells in embryonic tissues was correlated with the sites of arsenite toxicity and EGFP expression. The EGFP values quantified using the standard curve equation from the known GFP quantity were consistent with the arsenite-induced EGFP expression pattern and arsenite concentration, indicating that this technique can be a reliable and applicable measurement. In conclusion, we propose that fluorescence-based EGFP quantification in transgenic fish containing the hsp70 promoter-EGFP reporter-gene construct is a useful indicator of development toxicity caused by arsenite.     

Enhancement of sciatic nerve regeneration by adenovirus-mediated expression of dominant negative RhoA and Rac1

It is known that Rho family small GTPases activate a number of signal transduction pathways involved in cell cycle progression, gene expression, and cell survival. These small G proteins play an important role in neuronal survival and axon regeneration in neural injury. In this study, we tested whether the activity of RhoA or Rac1 regulates neurite extension in dorsal root ganglia (DRGs) in vitro and nerve regeneration in injured sciatic nerves. Regeneration of neurites from explanted DRGs was accelerated by combined suppression of RhoA and Rac1 activity using adenoviruses expressing dominant negative (DN) forms of both RhoA and Rac1 (Ad-Rho/RacDN) in vitro. Rat sciatic nerves were cut and Ad-Rho/RacDN was injected into the proximal stumps. After bridge grafting with chitosan mesh tubes, muscle evoked potentials induced by transcranial electrical stimulation were recorded eight weeks postoperatively. The terminal latencies were shorter in the Ad-Rho/RacDN group than in the control group. Histological analysis revealed extensive regrowth of neurofilament-positive and myelinated axons within the tubes in the group that received Ad-Rho/RacDN. These findings suggest that combined regulation of RhoA and Rac1 using DN adenoviral transgenic methods has the potential to modify injured peripheral nerve tissues directly.     

Participation of bone marrow-derived cells in hippocampal vascularization after status epilepticus

PurposeDiseases such as temporal lobe epilepsy, brain trauma and stroke can induce endothelial cell proliferation and angiogenesis in specific brain areas. During status epilepticus (SE), bone marrow-derived cells are able to infiltrate and proliferate, dramatically increasing at the site of injury. However, it is still unclear whether these cells directly participate in vascular changes induced by SE.MethodTo investigate the possible role of bone marrow-derived cells in angiogenesis after seizures, we induced SE by pilocarpine injection in previously prepared chimeric mice. Mice were euthanized at 8 h, 7 d or 15 d after SE onset.ResultsOur results indicated that SE modified hippocampal vascularization and induced angiogenesis. Further, bone marrow-derived GFP⁺ cells penetrated through the parenchyma and participated in the formation of new vessels after SE. We detected bone marrow-derived cells closely associated with vessels in the hippocampus, increasing the density of blood vessels that had decreased immediately after pilocarpine-induced SE.ConclusionWe conclude that epileptic seizures directly affect vascularization in the hippocampus mediated by bone marrow-derived cells in a time-dependent manner.     

抗肝癌单链免疫毒素在肝癌细胞系SMMC-7721中的表达

目的 构建分泌型抗肝癌单链免疫毒素真核表达载体并在人肝癌细胞系SMMC-7721中表达。方法 采用PCR方法在抗肝癌sFv的5′端引入引导序列使其能够在真核细胞中表达并分泌，在其下游连接人TNF-α基因，构建分泌型抗肝癌单链免疫毒素基因，并将该基因克隆人带有GFP报告基因的真核表达载体，用磷酸钙共沉淀法转染人肝癌细胞系SMMC-7721进行瞬时表达。结果 DNA序列分析证实在sFv的5′端引入正确的60bp引导肽序列，酶切鉴定证明成功构建了分泌型抗肝癌单链免疫毒素融合GFP真核表达载体，并在SMMC-7721细胞中成功地表达了融合荧光蛋白。结论 成功构建并表达了分泌型抗肝癌单链免疫毒素融合GFP基因，为肝癌免疫基因治疗的进一步研究奠定了基础。