管花苷B对抗H2O2诱导的PC12细胞凋亡

目的：观察肉苁蓉提取物管花苷B对H2O2诱导的PC12细胞损伤的影响。方法：用MTT法检测细胞存活率，以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化，DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生，并用荧光酶标仪测定caspase-3的活性。结果：100μmol·L^-1H2O2处理细胞24h显著降低细胞的存活率；诱导细胞发生凋亡，凋亡率达48．0％；细胞内活性氧水平及caspase-3的活性显著升高；而线粒体膜电位却明显降低，红／绿荧光强度的比值由正常的5．97降低为0．41左右。而预先给予1、10或100mg·L^-1浓度的管花苷B处理细胞12h，可显著提高细胞存活率；并可有效抑制DNA ladder的发生；流式细胞仪检测凋亡率分别降低到30．9％、18．3％和6．2％；激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平；并可逐渐恢复线粒体的高能量状态；caspase-3的活性不断降低，并呈现了一定的剂量依赖性。结论：管花苷B能显著地抑制H2O2诱导的PC12细胞凋亡，其神经细胞保护作用可能与其降低细胞内活性氧水平，维持线粒体膜电位的高能状态和抑制caspase-3的活性有关。     

管花苷B对抗H2O2诱导的PC12细胞凋亡

目的：观察肉苁蓉提取物管花苷B对H₂O₂诱导的PC12细胞损伤的影响。方法：用MTT法检测细胞存活率，以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化，DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生，并用荧光酶标仪测定caspase-3的活性。结果：100 μmol·L^-1 H₂O₂处理细胞24 h显著降低细胞的存活率；诱导细胞发生凋亡，凋亡率达48.0％；细胞内活性氧水平及caspase-3的活性显著升高；而线粒体膜电位却明显降低，红/绿荧光强度的比值由正常的5.97降低为0.41左右。而预先给予1、10或100 mg·L^-1浓度的管花苷B处理细胞12 h，可显著提高细胞存活率；并可有效抑制DNA ladder的发生；流式细胞仪检测凋亡率分别降低到30.9%、18.3%和6.2%；激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平；并可逐渐恢复线粒体的高能量状态；caspase-3的活性不断降低，并呈现了一定的剂量依赖性。结论：管花苷B能显著地抑制H₂O₂诱导的PC12细胞凋亡，其神经细胞保护作用可能与其降低细胞内活性氧水平，维持线粒体膜电位的高能状态和抑制caspase-3的活性有关。     

管花苷B对抗H202诱导的PCI2细胞凋亡

目的:观察肉苁蓉提取物管花苷B对H:O:诱导的PCI2细胞损伤的影响.方法:用MTr法检测细胞存活率,以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化,DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生,并用荧光酶标仪测定caspase-3的活性.结果:100 μmol稬-1H2O2处理细胞24 h显著降低细胞的存活率;诱导细胞发生凋亡,凋亡率达48.O％;细胞内活性氧水平及caspase-3的活性显著升高;而线粒体膜电位却明显降低,红／绿荧光强度的比值由正常的5.97降低为0.41左右.而预先给予l、10或100 mg.L-1浓度的管花苷B处理细胞12 h,可显著提高细胞存活率;并可有效抑制DNA ladder的发生;流式细胞仪检测凋亡率分别降低到30.9％、18.3％和6.2％;激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平;并可逐渐恢复线粒体的高能量状态;easpase-3的活性不断降低,并呈现了一定的剂量依赖性.结论:管花苷B能显著地抑制H2O2诱导的PCI2细胞凋亡,其神经细胞保护作用可能与其降低细胞内活性氧水平,维持线粒体膜电位的高能状态和抑制caspase-3的活性有关.     

雪胆素乙诱导刀豆蛋白A刺激的小鼠淋巴细胞凋亡及其机制的研究

 目的：分析雪胆素乙（CuIIb）对刀豆蛋白 A（Con A）刺激的小鼠淋巴细胞体外凋亡的影响,并探讨其作用机制。方法：以Annexin V染色结合流式细胞术分析小鼠淋巴细胞凋亡情况;利用JC-1染色分析淋巴细胞线粒体膜电位变化;Western blotting检测凋亡相关蛋白变化。结果：CuIIb处理后,早期和中期凋亡细胞比例明显增加,淋巴细胞线粒体膜电位降低。同时,CuIIb以剂量依赖方式激活caspase-3凋亡通路并明显降低抗凋亡蛋白survivin的表达。结论:CuIIb诱导淋巴细胞凋亡,其机制可能与其降低线粒体膜电位、激活caspase-3凋亡通路有关。     

β-细辛醚对缺糖缺氧再灌注损伤原代大鼠海马神经元的保护作用*

 目的：探讨β-细辛醚对缺糖缺氧再灌注损伤原代海马神经元的保护作用及其机制。方法：利用MTT法检测缺糖缺氧再灌注诱导的原代大鼠海马神经元的细胞活力,用分光光度法检测caspase-3的活性,用Western blotting法检测p-JNK和Bcl-2的蛋白表达,RT-PCR检测Bcl-2和caspase-3 mRNA表达。结果：与正常对照组比较,缺糖缺氧再灌注损伤组细胞活力明显下降,caspase-3活性明显升高,p-JNK蛋白表达和caspases-3 mRNA表达显著升高,Bcl-2蛋白表达显著降低,差异有统计学意义（均P＜0.05）。与缺糖缺氧再灌注损伤组比较,不同剂量β-细辛醚预处理组抑制了这些指标的改变（均P＜0.05）。结论：β-细辛醚通过抑制JNK介导的线粒体通路抑制缺糖缺氧再灌注诱导的原代海马神经元凋亡。     

透骨消痛胶囊对凋亡软骨细胞Rac1和Cdc42表达的影响CSCD

背景:透骨消痛胶囊治疗早、中期骨性关节炎有较好疗效,但作用机制尚未完全阐明。小GTP酶Rho能够抑制软骨细胞肥大分化,促进软骨细胞的凋亡。目的:观察透骨消痛胶囊对体外培养凋亡大鼠关节软骨细胞Rac1和Cdc42的影响,并初步探讨其防治骨性关节炎的作用机制。方法:采用4周龄SD大鼠膝关节软骨建立稳定的软骨细胞体外培养体系,采用甲苯胺蓝染色法对第3代软骨细胞进行鉴定。用20μg/L的肿瘤坏死因子α诱导体外培养软骨细胞的凋亡,诱导成功后,给予透骨消痛胶囊(500,100,20 mg/L)孵育24 h后,分别用MTT法检测各组软骨细胞的存活率,用流式细胞仪检测各组软骨细胞的线粒体膜电位情况,Western Blot检测各组软骨细胞Rac1,Cdc42,Bcl-2及Bax蛋白表达。结果与结论:透骨消痛胶囊能够减少肿瘤坏死因子α所致的软骨细胞凋亡,提高线粒体膜电位,提高细胞的存活率,同时能够下调Rac1,Cdc42,Bax蛋白的表达,上调Bcl-2蛋白表达,差异均有显著性意义(P<0.05)。提示透骨消痛胶囊可能通过下调Rac1,Cdc42和Bax蛋白表达,增加凋亡抑制基因Bcl-2蛋白表达,从而抑制软骨细胞的凋亡,而起到治疗骨性关节炎的疗效。     

氧化应激诱导HepG2肝癌细胞凋亡的研究(英)

目的：直接暴露细胞于活性氧能诱导发生凋亡，本文研究氧化应激诱导HepG2肝癌细胞的死亡及其机制。方法：暴露细胞于2 mmol/L过氧化氢产生氧化应激，用DNA凝胶电泳检测细胞凋亡，用荧光染色法检测细胞线粒体膜电位变化，Western blotting检测细胞浆中细胞色素c变化，fluorometric assay kit检测caspase活性变化。结果：氧化应激作用于HepG2细胞后12 h开始发生凋亡；氧化应激作用后4 h，细胞线粒体膜电位明显下降；胞浆中细胞色素c浓度呈时间依赖性增高；氧化应激作用8 h、12 h后细胞内caspase-3、caspase-9活性分别升高6.7及3.6倍，但caspase-8活性无变化。结论：氧化应激能诱导HepG2肝癌细胞发生凋亡，其途径与线粒体通路及caspase激活有关。     

水飞蓟素对同型半胱氨酸诱导的人脐静脉内皮细胞凋亡的抑制作用

目的：探讨水飞蓟素(SIL)对同型半胱氨酸(HCY)诱导的人脐静脉内皮细胞(HUVECs)凋亡的抑制作用及其作用机制。方法:采用MTT及LDH检测细胞活性，DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生, 流式细胞仪检测线粒体膜电位的变化,并用荧光酶标仪测定caspase-3，-6，-9的活性。Western blotting分析相关蛋白的表达。结果:1 mmol/L HCY使HUVECs的存活率比对照组低79.5%(P<0.01)，5-20 μg/L SIL明显抑制HCY所致的HUVECs死亡(P<0.05, P<0.01)，20 μg/L SIL可使HUVEC的存活率恢复到对照组的83.7%。HCY刺激后Bcl-2与XIAP的表达显著低于对照组，Bax的表达显著高于对照组，20 μg/L SIL可使Bcl-2凋亡蛋白的改变发生逆转。SIL可明显抑制 1 mmol/L HCY引起的caspase-3、caspase-6、caspase-9的升高。SIL明显抑制 1 mmol/L HCY引起的Δψm下降和Cyto C、Smac及AIF的释放。结论:SIL能抑制HCY诱导的人脐静脉内皮细胞凋亡, 其细胞保护作用可能与降低细胞内活性氧水平, 抑制caspase-3，-6，-9的活性和维持线粒体膜电位的高能状态有关。     

RIP3对BCG感染后小鼠巨噬细胞凋亡的调控作用研究

目的:探讨受体相互作用蛋白3(RIP3)在卡介苗(BCG)诱导小鼠巨噬细胞RAW264.7凋亡过程中的调控作用。方法:构建RIP3腺病毒干扰载体并感染巨噬细胞,并用BCG进行感染。采用噻唑蓝(MTT)比色法检测细胞活力;利用流式细胞术对细胞凋亡率、线粒体膜电位及活性氧含量进行检测;通过Western blot检测RIP3及凋亡相关蛋白的表达水平。结果:BCG感染RAW264.7细胞后,细胞活力下降且RIP3蛋白表达量显著上调(P0.01)。而与BCG单独感染组相比,BCG感染结合RIP3干扰处理组细胞凋亡率及活性氧含量降低,线粒体膜电位升高,同时促凋亡蛋白Bax与cleaved caspase-3的蛋白水平显著升高,抑凋亡蛋白Bcl-2的表达量显著降低(P0.01)。结论:在BCG感染小鼠巨噬细胞RAW264.7的过程中,RIP3参与了BCG诱导的RAW264.7细胞的凋亡,且该过程可能是通过线粒体途径实现的。     

第三丁基过氧化氢损伤皮层神经元线粒体并诱导凋亡

目的：探讨第三丁基过氧化氢（t-BHP）诱导大鼠皮层神经元凋亡的可能机制。 方法： 体外培养大鼠皮层神经元，MTT法测定细胞存活率，DNA断裂评价细胞凋亡，流式细胞术测定线粒体跨膜电位（ΔΨm），分光光度计法测定细胞内谷胱甘肽（GSH）浓度，Western blot法测定Bcl-2和Bax蛋白和胞浆细胞色素c以及活化型半胱氨酸天冬氨酸蛋白酶3（caspase-3）和多聚（ADP-核糖）聚合酶（PARP）水平。 结果： tBHP（25－400 μmol/L）可明显抑制皮层神经元的生长，引起ΔΨm下降和线粒体内细胞色素c向胞浆释放，同时细胞内GSH浓度以及Bcl-2蛋白水平下降，Bax蛋白水平增加，caspase-3和PARP得以激活并最终导致神经细胞凋亡。 结论： tBHP引起的氧化应激可通过损伤线粒体诱导皮层神经元凋亡。     

Hepatitis B Virus X Protein Sensitizes Primary Mouse Hepatocytes to Ethanol-and TNF-α-Induced Apoptosis by a Caspase-3-Dependent Mechanism

It is well-documented that alcohol drinking together with hepatitis viral infection accelerates liver injury;howeverthe underlying mechanisms remain unknown.In this paper,we demonstrated that primary hepatocytes fromtransgenic mice overexpressing hepatitis B virus X protein(HBX)were more susceptible to ethanol- and TNF-α-induced apoptotic killing.Compared to normal control mouse hepatocytes,ethanol and/or TNF-α treatment led toa significant increase in reactive oxygen species,mitochondrial permeability transition,cytochrome C release,caspase-3 activity,and poly(ADP-ribose)polymerase degradation in hepatocytes from HBX transgenic mice.Blocking caspase-3 activity antagonized ethanol-and TNF-α-induced apoptosis in primary hepatocytes from HBXtransgenic mice.Taken together,our findings suggest that HBX sensitizes primary mouse hepatocytes to ethanol-and TNF-α-induced apoptosis by a caspase-3-dependent mechanism,which may partly explain the synergisticeffects of alcohol consumption and hepatitis B virus infection on liver injury.Cellular & Molecular Immunology.2005;2(1):40-48.     

光敏化促进姜黄素诱导人胃癌MGC-803细胞凋亡

目的: 探讨光敏化促进姜黄素诱导人胃癌MGC-803细胞凋亡及其机制。方法: 用MTT法检测光敏化姜黄素对胃癌MGC-803细胞株的增殖抑制率,Hoechst 33258荧光染色观察细胞核形态的变化,流式细胞术检测细胞的凋亡率、线粒体膜电位、细胞内活性氧和Ca²⁺;比色法检测caspase-3、8和9酶活性;Western blotting分析细胞色素C、Bcl-2、Bax和热休克蛋白70(HSP70)水平。结果: 单纯姜黄素(5.0μmol/L)对MGC-803细胞增殖抑制率为(29.74±2.30)%,在光学显微镜下可见部分凋亡细胞,凋亡率为(12.54±1.75)%。而光敏化姜黄素组细胞增殖抑制率则为(44.93±3.61)%,在光学显微镜下能见明显细胞核形态改变,染色质凝集,凋亡小体形成,凋亡率为(26.58±2.67)%,细胞周期主要阻滞于G₀/G₁期。光敏化姜黄素显著降低线粒体膜电位,显著增加细胞色素C、细胞内活性氧和Ca²⁺以及caspase-3、8和9酶活性,与单纯姜黄素组比较,差异显著(P<0.01)。Western blotting结果显示光敏化姜黄素同时显著抑制Bcl-2和HSP70蛋白表达水平。结论: 光敏化姜黄素通过Bcl-2和线粒体途径增强其诱导胃癌MGC-803细胞凋亡的作用。     

Thimerosal induces neuronal cell apoptosis by causing cytochrome c and apoptosis-inducing factor release from mitochondria

There is a worldwide increasing concern over the neurological risks of thimerosal (ethylmercury thiosalicylate) which is an organic mercury compound that is commonly used as an antimicrobial preservative. In this study, we show that thimerosal, at nanomolar concentrations, induces neuronal cell death through the mitochondrial pathway. Thimerosal, in a concentration- and time-dependent manner, decreased cell viability as assessed by calcein-ethidium staining and caused apoptosis detected by Hoechst 33258 dye. Thimerosal-induced apoptosis was associated with depolarization of mitochondrial membrane, generation of reactive oxygen species, and release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to cytosol. Although thimerosal did not affect cellular expression of Bax at the protein level, we observed translocation of Bax from cytosol to mitochondria. Finally, caspase-9 and caspase-3 were activated in the absence of caspase-8 activation. Our data suggest that thimerosal causes apoptosis in neuroblastoma cells by changing the mitochondrial microenvironment.     

HIE幼龄大鼠神经元自噬诱导线粒体功能障碍的研究

目的:探讨细胞自噬对缺氧缺血性脑病(HIE)幼龄大鼠神经元线粒体功能的影响。方法:随机选取10日龄SPF级SD大鼠30只,分为假手术(sham)组和HIE组,后者结扎单侧颈总动脉复制缺血缺氧模型。取脑组织行镜下病理观察,免疫组化分析活化型caspase-3和LC3B-II蛋白表达;体外实验中观察缺氧诱导的原代大鼠神经元的自噬过程,Western blot检测相关蛋白,并对大鼠神经元线粒体功能进行测试。结果:(1)与sham组相比,HIE组大鼠出现脑萎缩和脑室增宽;HIE组免疫组化显示活化型caspase-3和LC3B-II蛋白表达上调(P<0.01);(2)体外细胞实验发现,缺氧可诱导大鼠神经元出现自噬和凋亡;(3)与sham组相比,单纯缺氧的神经元内活性氧簇增加,线粒体超氧化物上调,线粒体跨膜电位降低(P<0.01)。结论:在HIE大鼠模型中,缺氧诱导的神经元线粒体功能障碍,可能与缺氧时神经元出现的自噬和凋亡有关。这一结果将为临床上开发细胞自噬因子类药物治疗HIE提供了新的思路。     

衰老血管内皮细胞线粒体膜电位与活性氧的变化

背景：血管内皮细胞衰老、凋亡与再生的平衡对正常血管的功能维持具有极其重要的作用。而线粒体是机体细胞内的重要细胞器,除了合成ATP为细胞提供能量外,还控制细胞程序性死亡、以及衰老等多种病理生理的代谢过程。 目的：通过检测脐静脉内皮细胞传代过程中线粒体膜电位与活性氧的改变及其相互关系,从而探讨细胞衰老过程中所产生的功能障碍。 方法：体外培养人脐静脉内皮细胞,选取传代过程中的第2,4,6,8代细胞,采用流式细胞术检测细胞线粒体膜电位及活性氧变化。选取第2,8代细胞行透射电镜检查,观察正常及衰老细胞超微结构的改变。 结果与结论：传代衰老过程中,血管内皮细胞线粒体膜电位逐代降低,而胞内活性氧则出现由增加转而降低的过程。传代后期血管内皮细胞同早期内皮细胞相比,线粒体及内质网明显减少。说明内皮细胞在传代导致的复制性衰老过程中,线粒体膜电位降低,线粒体受损。而在早期传代过程中线粒体轻度受损,而活性氧产生增加,但在线粒体严重受损、功能严重退化过程中,活性氧产生降低。     

Fatty acid-induced apoptosis in neonatal cardiomyocytes: redox signaling

Exposure of neonatal rat cardiac myocytes to palmitate and glucose produces apoptosis as seen by cytochrome c release, caspase 3-like activation, DNA laddering, and poly(ADP-ribose) polymerase cleavage. The purpose of this study was to understand the role of reactive oxygen species in the initiation of programmed cell death by palmitate. We found that palmitate (but not oleate) produces inhibition of carnitine palmitoyltransferase I, accumulation of ceramide, and inhibition of electron transport complex III. These events are subsequent to cytochrome c release and loss of the mitochondrial membrane potential. No differences in H2O2 production or N-terminal c-Jun kinase phosphorylation were detected between myocytes incubated in palmitate and control myocytes (nonapoptotic) incubated in oleate. These results suggest that the palmitate-induced loss of the mitochondrial membrane potential is not associated with H2O2 synthesis and that a membrane potential is required to generate reactive oxygen species following ceramide inhibition of complex III.     

晚期糖基化终末产物通过氧化应激诱导大鼠软骨细胞损伤

目的:探讨晚期糖基化终末产物(advanced glycation end products,AGEs)能否通过氧化应激引起大鼠软骨细胞损伤。方法:原代培养SD大鼠软骨细胞,对细胞表型进行鉴定;应用CCK-8法检测软骨细胞生存率;DCFH-DA染色荧光显微镜下检测胞内活性氧簇(reactive oxygen species,ROS)的水平;Hoechst 33342核染色法及Annexin V-FITC/PI流式细胞法测定软骨细胞的凋亡率;RT-PCR法检测软骨细胞中Bax、Bcl-2、caspase-3、MMP3、MMP13和COL2的mRNA水平;Western blotting法检测软骨细胞中cleaved caspase-3、MMP3、MMP13和COL2的蛋白水平。结果:与对照组相比,AGEs可显著上调胞内ROS水平(P0.05),但经抗氧化剂N-乙酰半胱氨酸(NAC)抑制后ROS的生成明显减少(P0.05);另外,NAC可抑制AGEs引起的软骨细胞凋亡相关分子Bax/Bcl-2和caspase-3水平的上调,并减少MMP3和MMP13表达及COL2的丢失(P0.05)。结论:AGEs可通过氧化应激诱导大鼠软骨细胞损伤。     

Dynamin-related protein 1 is implicated in endoplasmic reticulum stress-induced pancreatic β-cell apoptosis

Pancreatic β-cell dysfunction is a critical component in the pathogenesis of diabetes. Endoplasmic reticulum (ER) stress is one of the factors that induces pancreatic β-cell dysfunction, but the underlying mechanisms have not been well elucidated. In this study, we report that a mitochondrial fission modulator, dynamin-related protein 1 (DRP-1), plays an important role in ER stress-induced β-cell apoptosis. Induction of DRP-1 expression significantly promoted ER stress-induced apoptosis in the DRP-1 WT (DRP-1 wild- type) inducible β-cell line, but not in the DRP-1 K38A (a dominant negative mutant of DRP-1) inducible β-cell line. We further demonstrated that the mitochondrial membrane potential decreased, and that cytochrome c release, caspase-3 activation and generation of reactive oxygen species (ROS) were enhanced by induction of DRP-1 WT, but prevented by DRP-1 K38A in pancreatic β-cells under ER stress conditions. These results indicate that DRP-1 mediates ER stress-induced pancreatic β-cell apoptosis.     

Biochemical and molecular basis of thimerosal-induced apoptosis in T cells: a major role of mitochondrial pathway

The major source of thimerosal (ethyl mercury thiosalicylate) exposure is childhood vaccines. It is believed that the children are exposed to significant accumulative dosage of thimerosal during the first 2 years of life via immunization. Because of health-related concerns for exposure to mercury, we examined the effects of thimerosal on the biochemical and molecular steps of mitochondrial pathway of apoptosis in Jurkat T cells. Thimerosal and not thiosalcylic acid (non-mercury component of thimerosal), in a concentration-dependent manner, induced apoptosis in T cells as determined by TUNEL and propidium iodide assays, suggesting a role of mercury in T cell apoptosis. Apoptosis was associated with depolarization of mitochondrial membrane, release of cytochrome c and apoptosis inducing factor (AIF) from the mitochondria, and activation of caspase-9 and caspase-3, but not of caspase-8. In addition, thimerosal in a concentration-dependent manner inhibited the expression of XIAP, cIAP-1 but did not influence cIAP-2 expression. Furthermore, thimerosal enhanced intracellular reactive oxygen species and reduced intracellular glutathione (GSH). Finally, exogenous glutathione protected T cells from thimerosal-induced apoptosis by upregulation of XIAP and cIAP1 and by inhibiting activation of both caspase-9 and caspase-3. These data suggest that thimerosal induces apoptosis in T cells via mitochondrial pathway by inducing oxidative stress and depletion of GSH.     

Mechanistic study of apoptosis induced by high-fluence low-power laser irradiation using fluorescence imaging techniques

Low-power laser irradiation (LPLI) can cause cell proliferation, differentiation, or death; however, the cellular mechanisms of these effects of LPLI, at high or low fluences, are not well known. To investigate the mechanism of high-fluence LPLI-induced apoptosis, both human lung adenocarcinoma cells (ASTC-a-1) and African green monkey SV40-transformed kidney fibroblast cells (COS-7) were irradiated with a He-Ne laser for 10 min under a fluence of 120 J/cm(2) and 80 J/cm(2), respectively. The dynamics of reactive oxygen species (ROS) generation was determined by measuring changes in fluorescence resulting from oxidation of intracellular dichlorodihydrofluorescein diacetate (H(2)DCFDA) to (DCF). The changes of mitochondrial membrane potential, DeltaPsim, were studied by measuring the reduction of cellular fluorescence of Rhodamine 123 dyes using confocal laser scanning microscopy. The activation of caspase-3 in cells transfected by [SCAT3] reporters was observed using fluorescence resonance energy transfer (FRET) imaging. The activity of caspase-8 during high-fluence LPLI-induced apoptosis was studied by monitoring the cellular distribution of [Bid-CFP] reporters using fluorescence imaging. The following temporal sequence of cellular events was observed during apoptosis induced by high-fluence LPLI (120 J/cm(2), ASTC-a-1 cells): (1) immediate generation of mitochondrial ROS following laser irradiation, reaching a maximum level 60 min after irradiation; (2) onset of DeltaPsim decrease 15 min after laser irradiation, reaching a minimum level 50 min after irradiation; and (3) activation of caspase-3 between 30 min and 180 min after laser irradiation. Our results also show that the high-fluence LPLI does not activate caspase-8, indicating that the induced apoptosis was initiated directly from mitochondrial ROS generation and DeltaPsim decrease, independent of the caspase-8 activation.