川芎嗪对缺血再灌注大鼠心肌细胞凋亡的影响

 目的 观察川芎嗪(Tetramethylpyrazine,TMP)对缺血心肌细胞凋亡以及病理组织学改变的作用.方法 采用大鼠心肌缺血再灌注(Myocardial ischemic reperfusion,MIR)损伤模型,用缺口末端标记技术(TDT-mediated dUTP nick end labeling,TUNEL)法检测MIR过程中不同时间点缺血心肌细胞凋亡的动态变化及川芎嗪对其影响,并采用电镜观察其病理组织学改变进行对照研究.结果 (1)非缺血心肌无TUNEL阳性细胞出现,MIR 60 min大鼠缺血心肌中可见TUNEL阳性细胞,120 min时TUNEL阳性细胞数目最多.(2)与单纯MIR大鼠相比,川芎嗪干预MIR大鼠缺血心肌细胞中TUNEL阳性细胞数明显减少,心肌缺血再灌注60 min时分别为(36.30±8.76)个,张和(24.70±7.15)个/张(P<0.05),120 min时分别为(48.43±23.87)个/张和(10.04±8.11)个,张(P<0.01).(3)电镜结果显示MIR 60 min时,心肌缺血性改变最明显,川芎嗪干预大鼠再灌注组心肌缺血损伤有一定减轻.结论 心肌缺血再灌注可诱导心肌细胞发生凋亡,且随再灌注时间的延长,心肌细胞凋亡数目逐渐增多.川芎嗪干预可使缺血心肌细胞凋亡减少,病理组织学改变亦有减轻.     

硬膜外注射吗啡对兔急性缺血再灌注心肌细胞凋亡的影响

 目的 探讨硬膜外注射吗啡对兔心肌急性缺血再灌注损伤的保护作用.方法 采取开胸结扎左前降支(LAD)的急性心肌梗死模型.新西兰兔22只随机分成2组:①硬膜外吗啡组:经硬膜外注入吗啡(0.25 mg/kg,配成0.5 ml溶液);②对照组:经硬膜外注入生理盐水0.5 ml.再灌注4 h后取缺血部分心肌,用TUNEL法检测每200个心肌细胞细胞凋亡数.结果 硬膜外吗啡组凋亡细胞数明显低于对照组(60.6±7.5 vs 85.7±9.2),差异有统计学意义(P＜0.05).硬膜外吗啡组和对照组细胞凋亡百分比分别为30.3%和42.5%,差异有统计学意义(P＜0.05).结论 硬膜外注射吗啡能减少缺血再灌注心肌细胞凋亡的数量,对缺血再灌注心肌有明显的保护作用.     

心肌缺血再灌注损伤时细胞凋亡的分子机制

心肌是发生缺血再灌注损伤(ischemia reperfusion injury,IRI)最常见的组织之一。研究发现细胞凋亡可能是心肌发生缺血再灌注损伤(myocardialischemia reperfusion injury,MIRI)重要环节之一。细胞凋亡是由核细胞在内外因素作用下主要通过内源性DNA内切酶的激活而发生的细胞自然死亡过程。心肌细胞凋亡的机制与心肌IRI有着密切的关系。     

缺血预处理对兔心肌细胞凋亡的影响

 目的 探讨缺血预处理及缺血再灌注对兔缺血再灌注心肌细胞凋亡的影响.方法 制备兔缺血预处理(ischemic preconditioning,IP)、缺血再灌注损伤(I/R)模型,采用末端脱氧核苷酶转换酶介导的生物素平移缺口末端标记技术(transferase-mediated dUTP nick end labeling,TUNEL)检测心肌细胞凋亡情况.结果 RI组细胞凋亡率(43.37±4.82)%,IP组虽然也有一定的心肌细胞凋亡率(24.53±2.95)%,但较I/R组明显降低(P<0.01).IP组心肌梗死范围较I/R组明显减小.结论 心肌缺血再灌注损伤可诱发或加重心肌细胞凋亡,IP能明显减少缺血再灌注诱导的心肌细胞凋亡的发生率,能明显减少心肌梗死范围,减轻缺血再灌注损伤;IP能减少心肌梗死范围、减轻缺血再灌注损伤的机制可能与其能明显减少心肌细胞凋亡有关.     

硫氧还蛋白通过阻断过氧亚硝酸阴离子导致的蛋白硝基化减少缺血后心肌细胞凋亡

目的本研究旨在阐明硫氧还蛋白(Trx)心肌保护作用的机制.方法采用成年雄性小鼠心肌30 min缺血/3 h再灌注模型,再灌注前10 min随机给予磷酸缓冲液(PBS,对照)或重组人Trx (hTrx,2 mg/kg) 腹腔注射.在再灌注终末,摘取实验动物的心脏,分别检测心肌细胞凋亡和心肌组织中硝基酪氨酸的含量.结果再灌注前给予Trx可以显著减少缺血/再灌注导致的心肌细胞凋亡(P＜0.01);与对照组相比,Trx组心肌组织中硝基酪氨酸的含量显著减少 (4.8±0.53 比 9.5±0.86 pmol/mg蛋白质,P＜0.01), 提示Trx可能通过阻断蛋白硝基化和随后的细胞凋亡而发挥心脏保护作用.为了寻找Trx可以阻断蛋白硝基化的直接证据,在培养的成年心肌细胞给予SIN-1 (过氧亚硝酸阴离子供体) 50 μmol处理、或SIN-1 和hTrx(500 nmol)共同处理后,观察Trx 在过氧亚硝酸阴离子诱导的细胞凋亡中的作用.结果表明SIN-1 处理导致心肌细胞凋亡显著增加 (P＜0.01),Trx可以显著减少SIN-1导致的心肌细胞凋亡(P＜0.01) .结论硫氧还蛋白,一种新的抗凋亡和心肌保护分子,通过阻断过氧亚硝酸阴离子导致的蛋白硝基化和随后的细胞凋亡而发挥心脏保护作用.     

改构型aFGF减轻大鼠小肠缺血再灌注所致肠道细胞凋亡

目的研究改构型酸性成纤维细胞生长因子(m aFGF)对大鼠肠缺血再灌注损伤所致肠道细胞凋亡的影响。方法将54只大鼠随机分为假手术组、生理盐水对照组和m aFGF治疗组。假手术组大鼠暴露肠系膜上动脉(SMA),不夹闭。生理盐水对照组和m aFGF治疗组大鼠以SMA夹闭造成肠缺血45分钟,松夹形成缺血再灌注,于再灌注即刻分别静脉注射生理盐水0.1m l和m aFGF 4μg,缺血再灌注2、6、12、24小时,取小肠组织观察组织学改变,用末端脱氧核糖转移酶介导的生物素化脱氧尿嘧啶缺刻标记技术(TUNEL)检测肠道细胞凋亡率。结果组织学检查显示生理盐水对照组缺血再灌注2~24小时肠道损伤严重,m aFGF治疗组肠道损伤较生理盐水对照组有所减轻。细胞凋亡检测结果假手术组肠道细胞凋亡率很低,生理盐水对照组和m aFGF治疗组细胞凋亡率明显高于假手术组。缺血再灌注12小时,生理盐水对照组细胞凋亡率高达(62.8±1.7)%,而m aFGF治疗组为(42.5±2.6)%,两者有统计学差异(P<0.05)。结论m aFGF能减轻大鼠肠缺血再灌注所致的肠道细胞凋亡。     

氢饱和生理盐水对大鼠心肌缺血再灌注损伤的保护作用

目的 研究氢饱和生理盐水(氢水)对SD大鼠心肌缺血再灌注损伤的保护作用.方法 健康成年雄性SD大鼠36只,按数字表法随机分为假手术组、手术对照组(对照组)、氢水治疗组(氢水组),每组12只.假手术组只开胸,不做缺血再灌注处理;对照组和氢水组在冠状动脉左前降支阻断血流30 min后行再灌注24 h,造成心肌缺血再灌注损伤,氢水组再灌注5 min前以5 ml/kg腹腔注射氢水.对照组和氢水组再灌注24 h后检测左心室收缩压(LVSP)、左心室舒张压(LVDP)、左心室内压最大上升和下降速率[±(dP/dt) max]等心功能指标;用氯化三苯基四氮唑(TTC)染色观察心肌梗死面积,HE染色观察心肌损伤程度,并检测血浆和心肌中丙二醛(MDA)的表达以观察心肌氧化损伤程度,用TUNEL法检测心肌缺血区(area at risk,AAR)心肌细胞凋亡,分光光度法检测心肌凋亡酶caspase-3的表达,免疫组化检测心肌8-羟基鸟嘌呤(8-OHdG)的表达.假手术组在同时间点用相同方法观察或检测上述指标.结果 与对照组相比,氢水组心肌缺血再灌注损伤显著减轻,心肌组织病理性损伤减轻,脂质 和DNA过氧化损伤指标明显减低,心功能显著改善,心肌细胞凋亡减轻,caspase-3表达降低(氢水组0.278±0.092,对照组0.507±0.072),心肌梗死面积显著减少.结论 氢水可以有效减少心肌缺血再灌注损伤.     

大鼠急性心肌缺血再灌注心肌细胞凋亡与Bcl—2／Bax蛋白的表达

目的：为了证实急性心肌缺血再灌注过程中存在着不同程度的心肌细胞凋亡现象,初步研究心肌细胞凋亡与Bcl-2/Bax蛋白表达的关系。方法：电镜观察心肌细胞的超微结构变化,抽提心肌组织DNA琼脂糖凝胶电泳,TUNEL法原位标记凋亡的心肌细胞,免疫组化技术和图像分析技术检测心肌细胞内Bcl-2/Bax蛋白表达。结果：缺血及再灌注组电镜观察心肌细胞出现典型凋亡超微结构特征,TUNEL染色可见不同程度的心肌细胞凋亡阳性反应,DNA电泳显示在缺血再灌注2h组出现明显的DNA ladder,再灌注较在缺血组心肌细胞中Bcl-2表达明显降低（P＜0．05）,而Bax表达明显增高＊（P＜0．05）,结论：急性心肌缺血及再灌注能诱导不同程度的心肌细胞凋亡,Bcl-2/Bax基因对心肌细胞凋亡的发生有着重要的调控作用。     

糖尿病对大鼠心肌缺血预处理保护作用的影响

目的 探讨糖尿病对缺血预适应(IPC)在大鼠缺血再灌注心肌保护作用中的影响.方法 取糖尿病SD大鼠及非糖尿病SD大鼠各30只,分为非糖尿病对照组(A组)、非糖尿病缺血再灌注组(B组)、非糖尿病IPC组(C组)、糖尿病对照组(D组)、糖尿病缺血再灌注组(E组)、糖尿病IPC组(F组),每组10只.动物处死后建立离体心脏Langendorff灌注模型.对照组采用全心灌流90min,余不做任何处理;缺血再灌注组采用心脏平衡灌流30min后,缺血30min,再复灌30min;IPC组采用心脏平衡灌流10min,经2次缺血5min再灌注5rnin后,缺血30min,再复灌30min.比较各组复灌30min后心排血量(CO)、左室发展压(LVDP)、左室内压最大上升和下降速率(±dp/dtmax)的恢复率,检测缺血前及复灌30rain后冠脉流出液中肌酸激酶(CK)的活性和心肌组织中丙二醛(MDA)、超氧化物歧化酶(SOD)的含量,并计算心肌含水率.结果 与非糖尿病缺血再灌注组比较,非糖尿病IPC组CK活性、MDA含量、心肌含水率均明显降低,SOD含量明显增加,CO、LVDP、 dp/dtmax、-dp/dtmax恢复率明显增加(P<0.05).而糖尿病IFC组与糖尿病缺血再灌注组比较上述变化均不明显(P>0.05).结论 糖尿病可抑制IPC对大鼠缺血再灌注心肌的保护作用.     

18F-FDG PET/CT心肌“缺血记忆”显像的实验研究

目的 通过犬18F-FDG PET/CT动态显像探讨缺血心肌葡萄糖代谢改变(也称“缺血记忆”)和缺血程度的关系.方法 将8条杂种犬用随机抽签法分为球囊封堵20 min组(4条)和40 min组(4条),所有犬均行基础、缺血-再灌注1h和24 h的18F-FDG PET/CT动态心肌代谢显像(禁食12h以上),以及99Tcm-MIBI SPECT心肌灌注显像.利用葡萄糖摄取定量分析软件(Carimas Core)计算冠状动脉封堵区和非缺血区心肌的葡萄糖摄取率k(k缺血和k非缺血),获得两者比值K(K=k缺血/k非缺血).在3次PET/CT显像同期分别进行心脏超声检查,评价室壁运动情况.所有显像完成后处死犬,分别取缺血区、非缺血区心肌组织行组织病理学检查.同一实验组前后比较采用配对t检验,其他采用非参数检验分析.结果 2组犬基础心肌灌注显像未见异常,预封堵区心肌/非缺血区心肌18F-FDG摄取率比值K差异无统计学意义(1.02 ±0.06与1.03±0.05,Z=-0.29,P＞0.05),室壁运动正常.缺血-再灌注1h后2组心肌灌注显像亦未见异常,但缺血区18F-FDG摄取增加,40 min组的K值高于20 min组(2.31±0.13与1.87 ±0.09,Z=-2.31,P＜0.05),缺血心肌出现不同程度的室壁运动减弱.缺血-再灌注24h后2组心肌灌注显像未见异常,但40 min组的K值仍稍高于基础状态(1.15±0.02与1.03 ±0.05,=4.32,P＜0.05),而20 min组的K值与基础状态比较差异无统计学意义(1.05±0.04与1.02±0.06,=0.87,P＞0.05),2组室壁运动均未见异常.心肌组织检查示2组缺血部位心肌细胞排列整齐,心肌细胞间质无水肿出血,未见心肌细胞肌浆凝集或肌溶性破坏,也未见炎性反应.结论 心肌“缺血记忆”与缺血程度相关.18F-FDG PET/CT心肌“缺血记忆”显像可能在急性冠状动脉综合征患者的诊断、治疗方面具有重要应用价值.     

门控SPECT心肌灌注显像评估急性心肌梗死患者心肌挽救量的研究进展

急性心肌梗死（AMI）患者经皮冠状动脉介入治疗（PCI）的目的在于尽可能地挽救濒死心肌。心肌挽救量（MS）与患者能否获益密切相关,在PCI的疗效评估及预后判断中具有重要价值。评价MS需明确初始心肌危险区面积（AAR）和心肌最终梗死面积（FIS）,二者之差即为MS。通过急诊时和PCI后2次99Tcm-甲氧基异丁基异腈门控SPECT心肌灌注显像（GSMPI）可分别定量AAR和FIS,从而获得MS,结果客观、准确,其临床价值在早期的大样本研究中已得到肯定。但在急诊时行GSMPI受到很多限制,致使AAR较难获得。近年来有学者提出的新显像方案,仅通过PCI后早期行1次GSMPI即可测定AAR,替代了2次显像法计算得到MS,其可行性及在临床中的实用价值显著提高。同时,新显像方案也扩展了核素GSMPI在AMI诊疗中的应用范围,为AMI患者的危险度分层提供了补充信息。笔者拟对GSMPI评估AMI患者MS的新显像方案的机制、应用价值、优势及发展前景作一综述。     

Cesium-129 myocardial scintigraphy to quantify myocardial infarction in dogs.

The sizes of surgically induced acute myocardial infarctions were quantified in a study of 28 dogs. Four projections (right and left anterior oblique, anterior, and left lateral) were obtained with 129Cs myocardial scintigraphy. Control images, taken before surgery, were compared with images taken 24-72 hr after coronary artery ligation. From postmortem examination the size of the infarct was determined and expressed as a percentage of the total left ventricle. On a standard diagram four independent observers marked the infarcted areas in each projection, expressed the severity of involvement in each area, and determined overall infarction size as a percentage of the total left ventricle. A nonlinear least-squares method was also employed to derive the size of the infarct, using the results from each observer's diagram. There were positive correlations between each observer's percentage estimate and the autopsy results. The overall accuracy of the least-squares method was similar to that of the individual observers. In this study, Observer 3 proved that acute myocardial infarcts can be quantified accurately from multiple scintigraphic projections of the myocardium, but the other three observers had difficulty in estimating infarct size. This difficulty probably resulted from the lack of well-validated criteria to aid the observer in determining the area of infarction, the severity of involvement within that area, or the total size of a myocardial infarct. Improvement in these estimates will require the development of definitive criteria, the use of optical scanners or computer processing, and combinations of radionuclides.     

血浆心肌细胞损伤标志物检测急性心肌梗死患者心肌损伤的临床研究

目的 探讨血浆心肌细胞损伤标志物在检测急性心肌梗死（AMI）患者心肌损伤中的价值。 方法 采用放射免疫分析法测定184例AMI患者和60名健康体检者（正常对照组）血浆心肌肌钙蛋白I（CTnI）、TNF-α、高敏C反应蛋白（hs-CRP）和β₂微球蛋白（β₂-MG）水平,并进行比较性分析。同时测定它们诊断AMI的特异度、阳性、阴性预测值、准确率以及入院后3、6、9 h时的灵敏度。 结果 184例AMI患者血浆CTnI、TNF-α、hs-CRP和β₂-MG水平较正常对照组均显著升高（t_CTnI=6.384,P＜0.001;t_TNF-α=2.136,P＜0.05;t_hs-CRP=5.109,P＜0.001;t_β2-MG=3.185,P＜0.01）,以血浆CTnI和hs-CRP水平升高最为显著。血浆CTnI、TNF-α、hs-CRP和β₂-MG水平对AMI患者诊断的特异度分别为96.67%、51.67%、65.00%和48.33%。入院后3、6和9 h时对AMI患者诊断的灵敏度:血浆CTnI分别为21.74%、92.93%和98.37%;血浆TNF-α分别为17.93%、65.76%和69.02%;血浆hs-CRP分别为16.30%、78.26%和79.89%;血浆β₂-MG分别为21.20%、69.57%和74.46%;以血浆CTnI为最高。阳性、阴性预测值和有效率亦以血浆CTnI为最高,分别为89.67%、88.33%、89.24%。 结论 心肌细胞损伤标志物CTnI不仅是早期诊断AMI的有效指标,而且具有治疗随访的临床价值。     

急性心肌梗死再灌注治疗前后心肌血流和代谢的变化及临床意义

目的　探讨急性心肌梗死患者行经皮冠状动脉腔内成形术 (PTCA)和支架术后心肌血流、脂肪酸代谢及糖代谢的变化及其临床意义。方法　 2 2例急性心肌梗死患者 ,于发病后 4周行延迟PTCA ,术前 (急性期 )及术后 (慢性期 )分别行2 0 1 Tl、1 2 3I β 甲基碘苯脂十五烷酸 (BMIPP)SPECT显像及1 8F 脱氧葡萄糖 (FDG)PET心肌显像。将左心室分成 13个节段 ,采用 4级评分法对2 0 1 Tl、1 2 3I BMIPP显像放射性分布进行视觉评价 ,两者得分差为2 0 1 Tl BMIPP不匹配。在血流减低部位 ,定量测定1 8F FDG摄取。慢性期复查冠状动脉造影。结果　急性期心肌血流 脂肪酸代谢不匹配的节段 ,1 8F FDG摄取率明显高于匹配节段 [(76 .5± 10 .6 ) %和 (4 5 .8± 8.6 ) % ,P <0 .0 1],慢性期两者无明显差异。冠状动脉非再狭窄患者其慢性期2 0 1 Tl BMIPP不匹配 (0 .2 5± 0 .4 2 )及1 8F FDG摄取率 [(5 2 .1± 8.1) % ]较急性期 [0 .36± 0 .5 1和 (72 .8± 9.8) % ]明显降低 (P均 <0 .0 1) ;冠状动脉再狭窄患者其慢性期与急性期比较 ,2 0 1 Tl BMIPP不匹配及1 8F FDG摄取率无明显变化。结论　观察急性心肌梗死PTCA前后心肌血流 脂肪酸代谢及糖代谢的变化 ,可间接预测PTCA后再狭窄。     

Assessment of myocardial viability after myocardial infarction

Conclusions  The data presented above suggest that assessment of myocardial viability after MI, particularly in those patients with severe LV dysfunction, is important for the identification of those with the highest risk, in whom revascularization can be of clinical benefit. There is growing and consistent evidence that patients with relatively large areas of dysfunctional but viable myocardium after MI have improved function, symptoms, and survival with prompt revascularization compared with medical therapy alone. Most importantly, long-term survival with revascularization in these patients is comparable with that achieved with cardiac transplantation. There are several methods available to the clinician with which to investigate the presence of tissue viability, and the evidence suggests that the scintigraphic approaches are the most sensitive. These observations suggest that noninvasive investigation of the amount of ischemic myocardium should be an important component of the diagnostic evaluation of patients with severe LV dysfunction after MI. This approach will likely enhance the often difficult process of selecting patients with poor cardiac function in whom revascularization will likely improve both the quality and quantity of life.     

The role of myocardial perfusion imaging in evaluating patients with myocardial bridging

Background

Myocardial bridging (MB) is a common, congenital coronary-abnormality that is found on average in one out of every three adults at autopsy (Moehlenkamp et al in Circulation, 106:2616-2622, 2002; Erbel et al in Circulation, 120:357-359, 2009). However, its clinical significance and impact on myocardial ischemia remains controversial and unclear. Myocardial perfusion imaging (MPI) is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, and is frequently performed to evaluate the hemodynamic significance of MB. This study was undertaken to determine the use of MPI in evaluating MB and to identify the characteristics of MB associated with perfusion defects using MPI.

Methods and Results

Thirty-nine patients with MB of the left anterior descending (LAD) artery as documented by coronary angiography (CA) were enrolled for this study. None of the patients exhibited other forms of heart disease as determined by both CA and stress-rest MPI, no later than 1 month prior to the study. Using MPI, eight patients (20.5%) were found to have perfusion defects in the corresponding myocardial areas. This frequency was significantly higher when compared with results obtained by stress electrocardiogram. The difference in the mean systolic narrowing of bridging segments was statistically significant between patients with and without ischemia. The positive rate of reversible defects in patients with severe systolic narrowing was significantly higher than in patients with mild-to-moderate systolic narrowing. However, there was no significant difference either between the mean length of the tunneled artery in patients with and without abnormal MPI or the positive rate of abnormal MPI in patients with different locations of the tunneled artery.

Conclusions

MPI is an effective, noninvasive technique for the evaluation of patients with MB. The myocardial ischemia that resulted from bridging is associated more closely with the degree of systolic narrowing than with the length of tunneled artery or the location of MB.