多聚（ADP-核糖）聚合酶不同时空的表达特征对缺血性脑损伤细胞修复的影响

目的：研究局灶性脑缺血再灌注后多聚(ADP-核糖)聚合酶(PARP)表达的时空变化及其作用。方法：采用改良线栓法建立大鼠大脑中动脉缺血再灌注模型(MCAO-R)，运用免疫组织化学方法检测PARP(M，116000)，PARP(M，24000)和caspasse-3表达的时空变化，苏木精-伊红染色观察组织病理变化。结果：脑缺血2h再灌注12h，PARP(Mr116000)及caspase-3表达增多，且随再灌时间的延长而表达逐渐增多(P&;lt;0．05)，并向四周动态扩展。缺血3h组PARP(Mr16000)蛋白阳性表达也增强，但表达程度与缺血2h组相比略有下降，在再灌注3d时表达最少。缺血6h组PARP(Mr116000)蛋白表达减少，且不随再灌注时间的延长而有明显变化。而PARP(Mr24000)蛋白在缺血2h再灌注12h阳性表达增加，但不随缺血时间及再灌注时间的延长而明显变化，呈平稳的低水平表达，与caspase-3的变化趋势也无相关性。结论：在脑缺血再灌注损伤中PARP活化的主要损伤作用是坏死而非凋亡。     

神经调节素对缺血性脑损伤大鼠COX-2表达的影响

目的探讨神经调节素对大鼠局灶性脑缺血再灌注后COX-2表达的影响。方法实验分为假手术组、对照组和治疗组。采用线栓法制作大鼠左侧大脑中动脉阻塞再灌注（MCAO-R）模型,治疗组给予神经调节素干预治疗。于缺血1 h再灌注6 h1、2 h1、d、2 d、3 d7、d、14 d,对照组和治疗组采用免疫组化和原位杂交技术分别检测COX-2蛋白及COX-2 mRNA的表达。结果假手术组脑组织可见到少量COX-2阳性细胞。对照组缺血再灌注6 h后COX-2阳性细胞数开始增加,再灌注2 d后达高峰,然后阳性细胞逐渐减少,至14 d仍有表达。治疗组COX-2阳性细胞数相对较少,变化规律与对照组相似,同一时间点比较,治疗组均显著低于对照组（t=2.558~6.795,P〈0.05）。结论神经调节素可能通过抑制脑缺血再灌注后COX-2的表达,发挥其神经保护作用。     

聚ADP核糖聚合酶1在人类乳腺癌中的表达及其与临床预后相关因子的关系

目的研究聚ADP核糖聚合酶1(PARP-1)在人类乳腺癌中的表达及其与患者临床预后相关因子间的相关性。方法采用RT-PCR及免疫荧光染色技术,检测66例手术切除的人类乳腺癌组织及癌旁组织中PARP-1的表达,并分析乳腺癌患者的康复相关因子与PARP-1表达间的关系。结果与癌旁组织相比,94.9%(62/66)的癌组织中PARP-1 mRNA表达上调,90.9%(60/66)的癌组织中PARP-1蛋白表达上调。临床分期越晚、肿瘤分化程度越差,PARP-1的标记指数(LI)、表达指数(EI)越大;单纯癌、浸润癌患者中PARP-1的LI、EI值较大;乳腺癌转移患者的PARP-1的LI、EI值显著高于非转移患者。结论PARP-1基因在转录和翻译水平上的过表达与乳腺癌的分期、病理分级、病理类型、肿瘤转移等临床预后相关因子有关。     

亚低温对大鼠缺血性脑水肿及水通道蛋白AQP4表达的影响

背景：亚低温（28～35℃）正成为一种治疗急性缺血性卒中较有前景的方法，低温可有效地减轻脑水肿是其神经保护作用之一。 目的：观察亚低温对大鼠脑缺血再灌注后脑含水量和水通道蛋白4（AQP4）表达的影响，探讨亚低温脑保护的作用机制。 设计：随机对照实验。 单位：徐州医学院神经生物实验室。 材料：选择健康雄性SD大鼠110只，体质量250-300g，由徐州医学院实验动物中心提供[No．SYNK（苏）2002—0079]。应用SPsS11．0统计软件将大鼠随机分3组：①假手术组m=10）；②常温组（n=50）；③亚低温组（33℃，n=50）。常温组及亚低温组又分为缺血后再灌注6h，1d，2d，3d，7d各亚组，每亚组各10只大鼠。每组中5只用于脑含水量测定，5只用于苏木精-伊红染色及免疫组织化学染色。 方法：参考Pulsinelli方法对常温组及亚低温组大鼠制备四动脉结扎全脑缺血模型，缺血时间为15min。假手术组大鼠仅电凝双侧椎动脉及分离颈总动脉，不作结扎，手术后24h断头取脑。对常温组及亚低温组大鼠脑组织切片，HE染色及免疫组化染色，分别于再灌注后6h，1d，2d，3d，7d观察脑组织病理学和AQP4表达水平的动态变化；干湿重法测定各组大鼠各时间点脑含水量。 主要观察指标：①常温组及亚低温组大鼠脑组织病理学变化。②所有大鼠各时间点脑含水量及AQP4表达水平。 结果：①常温组大鼠在缺血再灌注后6h可见血管周围间隙增宽、细胞外间隙扩大、脑组织变疏松等脑组织水肿表现，以缺血再灌注后2d最明显；亚低温组大鼠各时间点与相应的常温组比较，脑组织水肿表现相对减轻。②常温组及亚低温组大鼠缺血再灌注后6h内即出现脑含水量增高，2d达高峰，7d时脑含水量明显减少，但仍高于假手术组。亚低温组脑含水量均较相应时间点的常温组少（6h，7d组P〈0．01，余各组P〈0．05）。③常温组及亚低温组大鼠AQP4表达水平在再灌注后6h增高，2d达最高水平，7d时明显降低，但仍较假手术组高。亚低温组AQP4表达水平均较相应时间点的常温组降低（P〈0．01）。 结论：脑缺血再灌注后AQP4表达水平的变化趋势与脑含水量变化趋势在时间上一致，表明AQP4表达上调可能是缺血性脑水肿形成的分子机制之一。亚低温可减轻缺血性脑水肿，而通过抑制AQP4表达可能是亚低温减轻缺血性脑水肿的作用机制之一。     

低氧预处理对大鼠缺血一再灌注性脑损伤中凋亡及Fas和Fas-L蛋白表达的影响

目的：观察分析低氧预处理对大鼠缺血-再灌注性脑损伤凋亡及Fas、Fas-L蛋白表达的影响。 方法：实验于2004-09／2006-04在新乡医学院神经生物学实验室完成。选择成年SD大鼠24只，随机抽签法分为假手术组、缺血-再灌注模型组、低氧预处理组，每组8只。参照Zea-Longa改良的动脉线栓法制备脑缺血-再灌注模型，以动物缺血侧上下肢体瘫痪，围绕缺血对侧呈逆时针绕圈（追尾现象）为模型制备成功表现。缺血-再灌注模型组大鼠缺血3h后再灌注24h。低氧预处理组的大鼠在以300mL／min流量灌入N2和O2混合气体的密闭容器中处理3h恢复12h后，采用动脉线栓法缺血3h再灌注24h后取材，经处理后制备切片；假手术组仅切开一侧皮肤暴露颈总动脉。各组切片标本采用苏木精-伊红染色、免疫组织化学染色及TUNEL染色，观察神经组织学特征，Fas、Fas-L蛋白表达和细胞凋亡情况。并在不同时间（缺血1，2，3h再灌注1，4，8，24h）观察大鼠神经功能缺失情况。 结果：纳入大鼠24只，均进入结果分析，无脱失值。①缺血3h再灌注8h后低氧预处理组神经行为缺失计分低于缺血-再灌注模型组[（0．6&;#177;0．5），（1．3&;#177;0．5）分，t=2．546，P=0．023]；再灌注24h后低氧预处理组神经功能缺失计分显著低于各缺血-再灌注模型组[（1．1&;#177;0．6），（0．4&;#177;0．5）分，t=2．376，P〈0．051。②神经组织学特征：缺血-再灌注模型组缺血区中心神经组织结构完全破坏。神经元大部分坏死，细胞间隙明显增宽。缺血边缘区神经元肿胀、形态变为角形或扇形，神经元周神经纤维呈空泡状或海绵状，神经胶质细胞肿胀。低氧预处理组损伤程度轻于缺血-再灌注模型组。③低氧预处理组在缺血半球亦可监测到凋亡细胞，右侧均为阴性，凋亡细胞形态与缺血-再灌注模型组相似，但数量少于缺血-再灌注模型组[（23．1&;#177;4．4），（39．4&;#177;2．4），P〈0．05]。④假手术组及非缺血侧大脑半球Fas、Fas-L蛋白表达微弱。缺血-再灌注模型组和低氧预处理组缺血侧Fas、Fas-L蛋白有明显表达，与假手术组比较差异有显著性意义[（27．3&;#177;2．8），（11．1&;#177;2．2），（0．8&;#177;1．2）个／视野，P〈0．05]，[（24．6&;#177;3．6），（9．6&;#177;1．7），（0．5&;#177;0．8）个／视野，P〈0．05]。低氧预处理组Fas、Fas-L蛋白表达水平显著低于缺血-再灌注模型组（P〈0．05）。 结论：低氧预处理可减轻局灶性缺血再灌注脑损伤，减少大鼠脑缺血-再灌注后的脑细胞凋亡和神经功能缺失。抑制Fas、Fas-L蛋白表达可能是其发挥保护作用的分子机制之一。     

亚低温对大鼠缺血性脑水肿及水通道蛋白AQP4表达的影响

背景:亚低温(28～35℃)正成为一种治疗急性缺血性卒中较有前景的方法,低温可有效地减轻脑水肿是其神经保护作用之一。目的:观察亚低温对大鼠脑缺血再灌注后脑含水量和水通道蛋白4(AQP4)表达的影响,探讨亚低温脑保护的作用机制。设计:随机对照实验。单位:徐州医学院神经生物实验室。材料:选择健康雄性SD大鼠110只,体质量250～300g,由徐州医学院实验动物中心提供[No.SYNK(苏)2002-0079]。应用SPSS11.0统计软件将大鼠随机分3组:①假手术组(n=10);②常温组(n=50);③亚低温组(33℃,n=50)。常温组及亚低温组又分为缺血后再灌注6h,1d,2d,3d,7d各亚组,每亚组各10只大鼠。每组中5只用于脑含水量测定,5只用于苏木精-伊红染色及免疫组织化学染色。方法:参考Pulsinelli方法对常温组及亚低温组大鼠制备四动脉结扎全脑缺血模型,缺血时间为15min。假手术组大鼠仅电凝双侧椎动脉及分离颈总动脉,不作结扎,手术后24h断头取脑。对常温组及亚低温组大鼠脑组织切片,HE染色及免疫组化染色,分别于再灌注后6h,1d,2d,3d,7d观察脑组织病理学和AQP4表达水平的动态变化;干湿重法测定各组大鼠各时间点脑含水量。主要观察指标:①常温组及亚低温组大鼠脑组织病理学变化。②所有大鼠各时间点脑含水量及AQP4表达水平。结果:①常温组大鼠在缺血再灌注后6h可见血管周围间隙增宽、细胞外间隙扩大、脑组织变疏松等脑组织水肿表现,以缺血再灌注后2d最明显;亚低温组大鼠各时间点与相应的常温组比较,脑组织水肿表现相对减轻。②常温组及亚低温组大鼠缺血再灌注后6h内即出现脑含水量增高,2d达高峰,7d时脑含水量明显减少,但仍高于假手术组。亚低温组脑含水量均较相应时间点的常温组少(6h,7d组P<0.01,余各组P<0.05)。③常温组及亚低温组大鼠AQP4表达水平在再灌注后6h增高,2d达最高水平,7d时明显降低,但仍较假手术组高。亚低温组AQP4表达水平均较相应时间点的常温组降低(P<0.01)。结论:脑缺血再灌注后AQP4表达水平的变化趋势与脑含水量变化趋势在时间上一致,表明AQP4表达上调可能是缺血性脑水肿形成的分子机制之一。亚低温可减轻缺血性脑水肿,而通过抑制AQP4表达可能是亚低温减轻缺血性脑水肿的作用机制之一。     

大鼠创伤性脑损伤后不同时间神经细胞凋亡的变化

背景创伤性脑损伤神经细胞存在着细胞凋亡.有研究证实Bcl-2基因参与人脑挫裂伤后神经细胞的凋亡.聚二磷酸腺苷核糖多聚酶(poly adeno-sine diphosphate ribose polymerase,PARP)是细胞凋亡的一个重要标志.目的通过对大鼠创伤性脑损伤后PARP降解与DNA片段化的时序关系的研究,了解大鼠创伤性脑损伤后神经细胞凋亡的变化进程.设计随机对照的实验研究.单位白求恩军医学院和白求恩国际和平医院.材料选择Wister大鼠30只,随机分为假手术组5只和脑损伤组25只.方法采用Feeney等的落体撞击法造成左顶叶局限性脑挫裂伤,落体致伤冲击力为500 g·cm(50 g,10 cm),分别于损伤后2,6,12,24,48 h处死取样.分别采用末端标记法测定DNA片段化,免疫组化法检测PARP降解.光镜下观察阳性细胞所在部位及形态,苏木精-伊红染色作对照观察.主要观察指标损伤后脑皮质PARP降解与DNA片段化阳性细胞数.结果脑损伤后2 h开始出现PARP降解,主要集中于损伤灶边缘部位.6 h开始出现DNA片段化,最高密度均集中于损伤灶边缘部位,随时间推移,损伤灶深部区可见散在单个阳性细胞.其中PARP降解高峰出现在12～24 h(48～46个阳性细胞/切片,t=-34.434,-41.196,P＜0.001).DNA片段化出现高峰在24～48h(60～56个阳性细胞/切片,t=-39.430,-61.933,P＜0.001).结论创伤性脑损伤后存在细胞凋亡,且PARP降解高峰出现早于DNA片段化.建议在脑损伤早期使用抑制PARP降解的药物,可延缓细胞的凋亡.     

低氧预处理对大鼠缺血-再灌注性脑损伤中凋亡及Fas和Fas-L蛋白表达的影响

目的押观察分析低氧预处理对大鼠缺血-再灌注性脑损伤凋亡及Fas、Fas-L蛋白表达的影响。方法押实验于2004-09/2006-04在新乡医学院神经生物学实验室完成。选择成年SD大鼠24只熏随机抽签法分为假手术组、缺血-再灌注模型组、低氧预处理组,每组8只。参照Zea-Longa改良的动脉线栓法制备脑缺血-再灌注模型熏以动物缺血侧上下肢体瘫痪,围绕缺血对侧呈逆时针绕圈穴追尾现象雪为模型制备成功表现。缺血-再灌注模型组大鼠缺血3h后再灌注24h。低氧预处理组的大鼠在以300mL/min流量灌入N2和O2混合气体的密闭容器中处理3h恢复12h后,采用动脉线栓法缺血3h再灌注24h后取材,经处理后制备切片;假手术组仅切开一侧皮肤暴露颈总动脉。各组切片标本采用苏木精-伊红染色、免疫组织化学染色及TUNEL染色,观察神经组织学特征熏Fas、Fas-L蛋白表达和细胞凋亡情况。并在不同时间(缺血1,2,3h再灌注1,4,8,24h)观察大鼠神经功能缺失情况。结果:纳入大鼠24只,均进入结果分析,无脱失值。①缺血3h再灌注8h后低氧预处理组神经行为缺失计分低于缺血-再灌注模型组眼穴0.6±0.5雪熏穴1.3±0.5雪分,t=2.546熏P=0.023演;再灌注24h后低氧预处理组神经功能缺失计分显著低于各缺血-再灌注模型组眼(1.1±0.6),(0.4±0.5)分,t=2.376熏P<0.05演。②神经组织学特征押缺血-再灌注模型组缺血区中心神经组织结构完全破坏。神经元大部分坏死,细胞间隙明显增宽。缺血边缘区神经元肿胀、形态变为角形或扇形熏神经元周神经纤维呈空泡状或海绵状熏神经胶质细胞肿胀。低氧预处理组损伤程度轻于缺血-再灌注模型组。③低氧预处理组在缺血半球亦可监测到凋亡细胞,右侧均为阴性,凋亡细胞形态与缺血-再灌注模型组相似,但数量少于缺血-再灌注模型组眼(23.1±4.4),(39.4±2.4),P<0.05演。④假手术组及非缺血侧大脑半球Fas、Fas-L蛋白表达微弱。缺血-再灌注模型组和低氧预处理组缺血侧Fas、Fas-L蛋白有明显表达,与假手术组比较差异有显著性意义眼穴27.3±2.8雪熏穴11.1±2.2雪熏穴0.8±1.2雪个/视野熏P<0.05演,眼穴24.6±3.6雪熏穴9.6±1.7雪熏穴0.5±0.8雪个/视野熏P<0.05演。低氧预处理组Fas、Fas-L蛋白表达水平显著低于缺血-再灌注模型组(P<0.05)。结论押低氧预处理可减轻局灶性缺血再灌注脑损伤,减少大鼠脑缺血-再灌注后的脑细胞凋亡和神经功能缺失。抑制Fas、Fas-L蛋白表达可能是其发挥保护作用的分子机制之一。     

短暂脑缺血再灌注后突触蛋白I表达与细胞凋亡

目的:观察短暂脑缺血再灌注对与神经元的早期发育和再生相关的突触蛋白I及神经细胞凋亡的影响,进一步了解神经系统的可塑性。方法:实验于2003年于同济医院神经内科实验室进行。①分组:取75只Wister大鼠随机分为模型组(n=51)、假手术组(n=18)和正常对照组(n=6)3组。假手术组18只和模型组18只分为再灌注1,3,6,12,24和72h6个亚组,进行突触蛋白I检测;正常对照组6只和模型组剩余的33只大鼠(分为再灌注1,3,6,12,24,48和72h7个亚组)分别进行TUNEL阳性细胞检测、形态学观察和流式细胞仪检测,需获取数据时至少检测2只大鼠。②造模:模型组采用线栓法建立大鼠大脑中动脉闭塞模型,缺血10min后再灌注;假手术组不插入线栓,其余步骤同模型组;正常对照组不干预。③观察指标:于相应时间点麻醉状态下处死取脑,应用免疫组织化学的方法观察缺血侧额顶叶皮质突触蛋白I表达的动态变化,同时采用荧光显微镜、流式细胞仪和脱氧核苷酸末端转移酶介导的缺口末端标记法检测细胞凋亡情况,分析两者之间的关系。结果:经补充后72只大鼠进入结果分析。①缺血侧额顶叶皮质突触蛋白I的表达:模型组再灌注12h内无明显变化,再灌注24h低于假手术组(0.199±0.006,0.238±0.008,P<0.01),至72h恢复至假手术组水平。②细胞凋亡率:模型组再灌注24,48和72h均高于正常对照组[(12.57±9.83)%,(13.56±2.28)%,(16.68±0.66)%,(4.65±0.03)%,P<0.05]。③TUNEL阳性细胞率:正常对照组和模型组再灌注0～24h均未见阳性细胞,再灌注48和72h分别为(47.50±3.85)%和(62.66±13.06)%。结论:短暂脑缺血再灌注后存在着突触蛋白I表达的短暂降低,且与凋亡细胞的出现在时间上非常吻合,提示短暂脑缺血再灌注后存在失神经及其后的神经再获现象,这可能与DNA的损伤和修复有关。     

短暂脑缺血再灌注后突触蛋白Ⅰ表达与细胞凋亡

目的观察短暂脑缺血再灌注对与神经元的早期发育和再生相关的突触蛋白Ⅰ及神经细胞凋亡的影响,进一步了解神经系统的可塑性.方法实验于2003年于同济医院神经内科实验室进行.[1]分组取75只Wister大鼠随机分为模型组(n=51)、假手术组(n=18)和正常对照组(n=6)3组.假手术组18只和模型组18只分为再灌注1,3,6,12,24和72 h6个亚组,进行突触蛋白Ⅰ检测;正常对照组6只和模型组剩余的33只大鼠(分为再灌注1,3,6,12,24,48和72 h 7个亚组)分别进行TUNEL阳性细胞检测、形态学观察和流式细胞仪检测,需获取数据时至少检测2只大鼠.[2]造模模型组采用线栓法建立大鼠大脑中动脉闭塞模型,缺血10 min后再灌注;假手术组不插入线栓,其余步骤同模型组;正常对照组不干预.[3]观察指标于相应时间点麻醉状态下处死取脑,应用免疫组织化学的方法观察缺血侧额顶叶皮质突触蛋白Ⅰ表达的动态变化,同时采用荧光显微镜、流式细胞仪和脱氧核苷酸末端转移酶介导的缺口末端标记法检测细胞凋亡情况,分析两者之间的关系.结果经补充后72只大鼠进入结果分析.[1]缺血侧额顶叶皮质突触蛋白Ⅰ的表达模型组再灌注12 h内无明显变化,再灌注24 h低于假手术组(0.199±0.006,0.238±0.008,P＜0.01),至72 h恢复至假手术组水平.[2]细胞凋亡率模型组再灌注24,48和72 h均高于正常对照组[(12.57±9.83)%,(13.56±2.28)%,(16.68±0.66)%,(4.65±0.03)%,P＜0.05].[3]TUNEL阳性细胞率正常对照组和模型组再灌注0～24h均未见阳性细胞,再灌注48和72 h分别为(47.50±3.85)%和(62.66±13.06)%.结论短暂脑缺血再灌注后存在着突触蛋白Ⅰ表达的短暂降低,且与凋亡细胞的出现在时间上非常吻合,提示短暂脑缺血再灌注后存在失神经及其后的神经再获现象,这可能与DNA的损伤和修复有关.     

Burn and smoke injury activates poly(ADP-ribose)polymerase in circulating leukocytes

The nuclear enzyme poly(ADP-ribose)polymerase (PARP) plays a significant role in the pathogenesis of various forms of critical illness. DNA strand breaks induced by oxidative and nitrative stress trigger the activation of PARP, and PARP, in turn, mediates cell death and promotes proinflammatory responses. Until recently, most studies focused on the role of PARP in solid organs such as heart, liver, and kidney. We investigated the effect of burn and smoke inhalation on the levels of poly(ADP-ribosylated) proteins in circulating sheep leukocytes ex vivo. Adult female merino sheep were subjected to burn injury (2× 20% each flank, 3 degrees) and smoke inhalation injury (insufflated with a total of 48 breaths of cotton smoke) under deep anesthesia. Arterial and venous blood was collected at baseline, immediately after the injury and 1 to 24 h after the injury. Leukocytes were isolated with the Histopaque method. The levels of poly(ADP-ribosyl)ated proteins were determined by Western blotting. The amount of reactive oxygen species was quantified by the OxyBlot method. To examine whether PARP activation continues to increase ex vivo in the leukocytes, blood samples were incubated at room temperature or at 37°C for 3 h with or without the PARP inhibitor PJ34. To investigate whether the plasma of burn/smoke animals may trigger PARP activation, burn/smoke plasma was incubated with control leukocytes in vitro. The results show that burn and smoke injury induced a marked PARP activation in circulating leukocytes. The activity was the highest immediately after injury and at 1 h and decreased gradually over time. Incubation of whole blood at 37°C for 3 h significantly increased poly(ADP-ribose) levels, indicative of the presence of an ongoing cell activation process. In conclusion, PARP activity is elevated in leukocytes after burn and smoke inhalation injury, and the response parallels the time course of reactive oxygen species generation in these cells.     

Inhibitors of poly(ADP-ribose) polymerase modulate signal transduction pathways and the development of bleomycin-induced lung injury

Poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated by strand breaks in DNA, plays an important role in the tissue injury associated with inflammation. The aim of our study was to evaluate the therapeutic efficacy of in vivo inhibition of PARP in an experimental model of lung injury caused by bleomycin administration. Mice subjected to intratracheal administration of bleomycin developed significant lung injury and apoptosis (measured by Annexin V coloration). An increase of immunoreactivity to nitrotyrosine and PARP, as well as a significant loss of body weight and mortality, was observed in the lung of bleomycin-treated mice. Administration of the two PARP inhibitors 3-aminobenzamide (3-AB) or 5-aminoisoquinolinone (5-AIQ) significantly reduced the 1) loss of body weight, 2) mortality rate, 3) infiltration of the lung with polymorphonuclear neutrophils (myeloperoxidase activity), 4) edema formation, and 5) histological evidence of lung injury. Administration of 3-AB and 5-AIQ also markedly reduced nitrotyrosine formation and PARP activation. These results demonstrate that treatment with PARP inhibitors reduces the development of inflammation and tissue injury events induced by bleomycin administration in the mice.     

Inhibition of poly (ADP-ribose) polymerase attenuates acute lung injury in an ovine model of sepsis

It is known that in various pathophysiological conditions, reactive oxidants cause DNA strand breakage and subsequent activation of the nuclear enzyme poly(ADP ribose) polymerase (PARP). Activation of PARP results in cellular dysfunction. We hypothesized that pharmacological inhibition of PARP reduces the damage in the ovine model of acute lung injury (ALI). After smoke inhalation, Pseudomonas aeruginosa (5 x 109 cfu/kg) was instilled into both lungs. All of the animals were mechanically ventilated with 100% O2. The infusion of the PARP inhibitor (INO-1001, n = 6) began 1 h after the injury and thereafter through 24 h (3 mg bolus + 0.3 mg/kg/h, i.v.). Control animals (n = 6) were treated with saline. Sham injury animals (n = 8) received sham smoke and were mechanically ventilated in the same fashion. One-half of those sham animals (n = 4) were given the same dose of INO-1001. PaO2/FiO2 ratio at 24 h in saline and in the INO-1001-treated groups were 95 +/- 22 and 181 +/- 22, respectively (P < 0.05). Peak airway pressure at 24 h in the saline- and INO-1001-treated groups was 32.6 +/- 3.0 and 24.4 +/- 2.2, respectively (P < 0.05). Pulmonary shunt fraction was also significantly attenuated. INO-1001 treatment reduced pulmonary histological injury and attenuated poly (ADP-ribose) accumulation in the lung. In conclusion, inhibition of PARP improved the ALI after smoke inhalation and pneumonia. The results suggest that the activation of PARP plays a role in the pathophysiology of ALI in sheep.     

Preclinical selection of a novel poly(ADP-ribose) polymerase inhibitor for clinical trial

Poly(ADP-ribose) polymerase (PARP)-1 (EC 2.4.2.30) is a nuclear enzyme that promotes the base excision repair of DNA breaks. Inhibition of PARP-1 enhances the efficacy of DNA alkylating agents, topoisomerase I poisons, and ionizing radiation. Our aim was to identify a PARP inhibitor for clinical trial from a panel of 42 potent PARP inhibitors (K(i), 1.4-15.1 nmol/L) based on the quinazolinone, benzimidazole, tricyclic benzimidazole, tricyclic indole, and tricyclic indole-1-one core structures. We evaluated chemosensitization of temozolomide and topotecan using LoVo and SW620 human colorectal cells; in vitro radiosensitization was measured using LoVo cells, and the enhancement of antitumor activity of temozolomide was evaluated in mice bearing SW620 xenografts. Excellent chemopotentiation and radiopotentiation were observed in vitro, with 17 of the compounds causing a greater temozolomide and topotecan sensitization than the benchmark inhibitor AG14361 and 10 compounds were more potent radiosensitizers than AG14361. In tumor-bearing mice, none of the compounds were toxic when given alone, and the antitumor activity of the PARP inhibitor-temozolomide combinations was unrelated to toxicity. Compounds that were more potent chemosensitizers in vivo than AG14361 were also more potent in vitro, validating in vitro assays as a prescreen. These studies have identified a compound, AG14447, as a PARP inhibitor with outstanding in vivo chemosensitization potency at tolerable doses, which is at least 10 times more potent than the initial lead, AG14361. The phosphate salt of AG14447 (AG014699), which has improved aqueous solubility, has been selected for clinical trial.     

Effect of poly(ADP-ribose) polymerase inhibition on outer medullary hypoxic damage

Poly(ADP-ribose) polymerase (PARP) activation after free-radical-induced DNA damage depletes cellular energy stores and participates in ischemia-reflow injury. We studied the potential protective effect of the water-soluble PARP inhibitor 3-aminobenzamide (3-AB) in a rat model of acute renal failure (ARF) from combined administration of radiocontrast, indomethacin and N(omega)-nitro-L-arginine methyl ester. Kidney function at 24 h was better preserved in rats treated with 3-AB as compared to control animals. However, the extent of tubular hypoxic damage was not significantly mitigated. It is concluded that PARP inhibition may attenuate renal dysfunction in this model of ARF with medullary hypoxic tubular injury even while the extent of tubular necrosis is not significantly altered. Further studies of this dyssynchrony of structure and function may provide important insights into the sequence of events that promotes renal failure after medullary injury.     

Activation of poly(ADP-ribose) polymerase in circulating leukocytes during myocardial infarction

Myocardial ischemia-reperfusion can lead to increased oxidative stress both locally and in circulating leukocytes. Oxidant-mediated DNA single strand breaks are known to activate the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in various forms of shock, inflammation, and ischemia-reperfusion injury. The aim of the current study was to investigate whether a local insult such as myocardial ischemia-reperfusion is sufficient to lead to activation of PARP in circulating leukocytes. In anesthetized rats myocardial ischemia-reperfusion was induced by transient ligation of the left anterior descending coronary artery. There was a marked increase in poly(ADP-ribosyl)ation of proteins in homogenates of leukocytes isolated from rats at the end of the reperfusion period. Poly(ADP-ribosyl)ation was inhibited by administration of the pharmacologic PARP inhibitor INO-1001 (30 mg/kg) to the rats. We conclude that local insults, such as myocardial reperfusion injury, are sufficient to activate PARP in circulating leukocytes. PARP activation in circulating cells may mediate certain systemic effects of local ischemia-reperfusion injury such as inflammatory mediator production and remote organ injury.     

Activation of poly(ADP-ribose) polymerase contributes to development of doxorubicin-induced heart failure

Activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) by oxidant-mediated DNA damage is an important pathway of cell dysfunction and tissue injury in conditions associated with oxidative stress. Increased oxidative stress is a major factor implicated in the cardiotoxicity of doxorubicin (DOX), a widely used antitumor anthracycline antibiotic. Thus, we hypothesized that the activation of PARP may contribute to the DOX-induced cardiotoxicity. Using a dual approach of PARP-1 suppression, by genetic deletion or pharmacological inhibition with the phenanthridinone PARP inhibitor PJ34, we now demonstrate the role of PARP in the development of cardiac dysfunction induced by DOX. PARP-1+/+ and PARP-1-/- mice received a single injection of DOX (25 mg/kg i.p). Five days after DOX administration, left ventricular performance was significantly depressed in PARP-1+/+ mice, but only to a smaller extent in PARP-1-/- ones. Similar experiments were conducted in BALB/c mice treated with PJ34 or vehicle. Treatment with a PJ34 significantly improved cardiac dysfunction and increased the survival of the animals. In addition PJ34 significantly reduced the DOX-induced increase in the serum lactate dehydrogenase and creatine kinase activities but not metalloproteinase activation in the heart. Thus, PARP activation contributes to the cardiotoxicity of DOX. PARP inhibitors may exert protective effects against the development of severe cardiac complications associated with the DOX treatment.