灰旱獭(Marmota baibacina)移动性的模拟实验

灰旱獭(Marmota baibacina)是珍贵的毛皮动物,也是我国天山山地鼠疫自然疫源地的主要储存宿主。研究该动物的生态学,对于阐明自然疫源地的动物流行病规律及指导制订消灭疫源性的措施具有重要的意义。 用标记动物进行动物生态学研究,国外于五十年代即已作了大量工作(PendletonR.C.1956)。一些苏联学者为解决鼠疫动物流行病的一些理论问题,进行了许多旱獭生态学研究。例如,Bn6n~os(1961,1962)用染色标记方法对灰旱獭的移动性进行了观察,把旱獭移动分为迁出式移动和种群内移动,Kn3nJios(1964)用染色标记法对红旱獭(Marmota caudata)的活动性和移动性进行了详细的观察;bepcuⅡgena(1966)用放射性同位素及染色标记法对灰旱獭的种群内接触进行了试验研究。     

Nitric oxide and oxygen radicals induced apoptosis via bcl-2 and p53 pathway in hypoxia-reoxygenated cardiomyocytes

Twotypesofcellulardemisecanoccursimultaneouslyintissuesorculturedcellbynecrosisandapoptosis.Lossofmembraneintegrity,celledemaandbreak,andthecellcomponentsre-leasedoutarethecharacteristicsofnecrosis.Whilethecellapoptosisisaprogramcelldeathcodedbygeneandactivatedseriousendogenousenzymes[1].Recentstudieshavedemonstratedthatmyocardialischemia-reperfusioninjuryresultedinapoptoticcelldeathinadditiontotissuenecrosis[2—4].Oxygenstressisoneofthereasonsthatcausedcellapoptosisandtheoxygenradicalsinthest…     

一氧化氮和氧自由基诱导缺氧再给氧心肌细胞凋亡的bcl-2和p53信号通路研究

观察了心肌缺氧再给氧损伤的一氧化氮(nitric oxide, NO)和氧自由基机制. 新生Wistar大鼠心肌细胞置于95% N₂ /5% CO₂环境培养24 h, 然后置于95% O₂ /5% CO₂环境培养4 h造成缺氧再给氧心肌细胞损伤模型. 单纯缺氧组心肌细胞置于95% N₂/5% CO₂环境培养24 h, 但不再给氧. NO供体硝普钠(SNP, 5 mmol/L)、NO合酶抑制剂Nw-硝基-L-精氨酸甲酯(L-NAME, 100 mmol/L)和其异构体Nw-硝基-D-精氨酸甲酯(D-NAME, 100 mmol/L)以及超氧化物歧化酶/过氧化氢酶(SOD/CAT, 各100 U/mL)分别于缺氧前加入培养基. 正常对照组心肌细胞置于95% 空气/5% CO₂环境下培养. 结果显示, 缺氧24 h能增加培养介质中NO, 硫代巴比妥酸反应产物(TBARS)和乳酸脱氢酶(LDH)水平, 再给氧降低培养介质中NO和 水平, 增加TBARS和LDH水平. 缺氧上调bcl-2和p53和p21/waf1/cip1蛋白表达水平, 而再给氧下调bcl-2蛋白表达水平, 上调p53和p21/waf1/cip1蛋白表达水平. 同时, 缺氧增加心肌细胞凋亡率, 而再给氧增加心肌细胞坏死率. NO供体硝普钠(SNP)增加培养介质中 和TBARS水平, 下调bcl-2蛋白表达而上调p53和p21/waf1/cip1蛋白表达水平, 增加DNA断裂、凋亡及坏死细胞率. L-NAME和 SOD/CAT分别降低培养介质中 和TBARS水平, 它们均能上调bcl-2蛋白表达而下调p53和p21/waf1/cip1蛋白表达水平, 抑制DNA断裂、凋亡及坏死细胞率, 而D-NAME则无此作用. 以上结果表明, 在缺氧再给氧所致心肌细胞死亡过程中, NO和氧自由基参与下调bcl-2蛋白表达水平和上调p53和p21/waf1/cip1蛋白表达水平, 相应地激发细胞凋亡程序, 并提示一氧化氮及氧自由基诱导心肌细胞凋亡的机制与调节 bcl-2和p53和p21/waf1/cip1信号通路有关.     

乙酸乙酯抽提法在ESR检测一氧化氮自由基中的应用

改进了用有机溶剂抽提检测一氧化氮(nitric oxide,NO)自由基的方法,并利用有机溶剂抽提法检测了小鼠心肌中NO的含量.有机溶剂可以把二乙基二硫代氨基甲酸钠(diethyldithiocarbamate, DETC)捕集NO的产物(DETC)₂-Fe²⁺-NO由水相中萃取并富集到酯相中,然后利用电子顺磁共振波谱仪(ESR)在常温下检测大体积样品中的NO.比较了几种不同的有机溶剂：正丁醇、乙酸丁酯、乙酸乙酯、三乙酸甘油酯、乙酸异戊酯等的萃取能力,发现乙酸乙酯是一种理想的提取溶剂.乙酸乙酯提取法可以使NO的量与ESR信号强度在20 μmol/L内有良好的线性,使ESR的检测灵敏度提高到200 nmol/L以下;(DETC)₂-Fe²⁺-NO对光比较敏感,见光易于分解;复合物在乙酸乙酯中避光保存于4℃可稳定十几天而无显著的变化.     

Nitric oxide and oxygen radicals induced apoptosis via bcl-2 and p53 pathway in hypoxia-reoxygenated cardiomyocytes

Neonatal rat cardiomyocytes were subjected to 24 h of hypoxia 95%N2/5%CO2 and 24 h of hypoxia plus 4 h of reoxygenation 95%O2/5%CO2. 24 h of hypoxia increased the levels of NO, TBARS and LDH. 24 h of hypoxia plus 4 h of reoxygenation decreased the levels of NO, but further increased TBARS and LDH. The hypoxia up-regulated the expression of bcl-2, p53 and p21/waf1/cip1 but the reoxygenation down-regulated the expression of bcl-2, and further up-regulated p53 and p21/waf1/cip1. The hypoxia increased cell apoptosis and reoxygenation further increased both apoptotic and necrotic cell death. NO, TBARS, DNA fragmentation and cell apoptosis were enhanced by SNP and inhibited by L-NAME respectively. In addition, SOD/catalase down-regulated the expression of p53, p21/wafl/cipl and TBARS but up-regulated bcl-2 and increased indirectly the level of NO, and inhibited DNA fragmentation. The results suggest that hypoxia-induced cell death is associated with the activation of NO, bcl-2 and p53 pathway, while hypoxia-reoxygenation induced cell death via the generation of reactive oxygen species and activation of p53 pathway. The present study clarified that NO may be an initiative signal to apoptotic cell death and the activation of bcl-2, p53 and p21/waf1/cip1 pathway in hypoxic and hypoxia-reoxygenated cardiomyocytes.