简介:摘要:目的:通过检测冷热循环前后低收缩复合树脂微拉伸强度,评价其粘结性能及冷热循环对其粘结长期稳定性的影响。方法:收集新鲜离体磨牙并制备冠中部牙本质粘结界面,随机分为两组后分别使用低收缩树脂粘结系统和 SE Bond粘结,复合树脂充填固化,制备柱状微拉伸试件。实验组浸泡于蒸馏水中进行冷热循环 10000次后进行微拉伸测试,对照组即刻进行测试。结果:微拉伸强度测试结果显示,冷热循环前后,低收缩复合树脂粘结系统的微拉伸强度之间的差异具有统计学意义( P<0.05)。无论是否进行冷热循环,低收缩复合树脂粘结系统的粘结强度大于 SE Bond( P<0.05)。结论:低收缩复合树脂具有良好的粘结性能,冷热循环对低收缩复合树脂粘结强度有影响。
简介:ToclarifytheroleofAPOBEC3G(A3G)incellulardefenseagainsthepatitisBvirus(HBV),theexpressionofA3GinnormalhumanliverandtheregulationoftheA3Gexpressioninhep-atomacellline(HuH-7)wereinvestigated.ExpressionlevelofAPOBEC3smRNAinhumanliverwasdeterminedbyRT-PCR.HuH-7andHepG2cellsweretreatedwithvariousconcentrationsofIFN-α(0U/ml,100U/ml,500U/ml,1000U/ml)for12h.ThemRNAlevelsweremeasuredbyaquantitativeRT-PCR,theresultswerenormalizedrelativetothespecimenswithoutIFN-αstimulation.TotalproteinofHuH-7cellstreatedwithvariousconcentrationsofIFN-αfor48hwassubjectedtoWesternblotanalysis.Forreportergeneassay,HuH-7cellsweretransfectedwiththereporterplasmidscontainingIRF-Esitesanditsmutantswithdifferentlengths.Thenthecellsweretreatedwithorwithout1200U/mlIFN-aforadditional12h(1000U/ml)after24hoftransfection,andthecelllysatewaspreparedandassayedforluciferaseactivity.ItwasfoundthatnormalhumanliverexpressedthemRNAofA3G.A3GmRNAexpressioninHuH-7andHepG2cellswereup-regulatedbyIFN-αstimulationinadose-depen-dentmanner.WesternblotanalysisindicatedthatA3GproteinexpressionwasalsoenhancedbyIFN-αstimulation.SequenceanalysisshowedtheexistenceofputativesitesofIFNregulatoryfactorelement(IRF-E)in5'regionofA3Ggeneupstreamtheinitiationcodon.IFN-αstimulationresultsin6-to8-foldincreaseinluciferaseactivityincellstransfectedwiththeplasmidcontainingIRF-Esitesofthe5'upstreamsequences,whereasluciferaseactivitydidnotchangeincellstransfectedwiththeplasmidcontainingmutantIRF-EsitesorwithoutIRF-Esites.Asaconclusion,A3Gareexpressedinnormalhumanliver.A3Gexpressionwasup-regulatedbyIFN-αstimulationinhepatomacellsandcouldbeinvolvedinhostdefensemechanismsagainstHBV.ERF-Esitein5'regionofAP0BEC3Ggeneupstreamtheinitiationcodonplaysanimportantroleinthisp