急性心肌梗死后氯通道基因表达的变化

目的:研究猪急性心肌梗死(AMI)后囊性纤维化跨膜转运调节氯通道(CFTR)和CIC-2型氯通道(CIC-2)基因表达的变化,探讨急性心肌梗死后早期室性心律失常发生的分子机制。方法:通过结扎猪左前降支远端1/3-1/2处2 h然后再灌注建立AMI模型,同时设立相应的假手术(SH)组。术后24 h取左心室梗死边缘区内层(En-do)、中层(Mid)和外层(Epi)心肌(SH组取对应位置心肌),应用逆转录-聚合酶链反应(RT-PCR)半定量分析氯通道CFTR和CIC-2的基因表达的改变。结果:与SH组相比,AMI后梗死边缘区三层心肌CFTR和CIC-2 mRNA表达均明显上升(P<0.05),而且三层心肌间的基因表达呈不均一性(P<0.05)。结论:AMI后梗死边缘区三层心肌氯通道CFTR和CIC-2基因表达的不均一性上调,可能是AMI后早期易发室性心律失常的分子机制之一。     

单导管射频消融治疗右心室心律失常的疗效与安全性

目的 探讨单导管射频消融治疗右心室室性心律失常(RVA)的疗效与安全性.方法 回顾性分析2003年5月至2008年5月温州医学院附属第二医院心内科收治的111例患者资料,其中男41例、女70例,年龄(45.2±16.7)岁.其中右心室流出道(RVOT)室性心律失常104例[室性心动过速(VT)13例,室性早搏(PVC)91例],右心室流人道PVC 7例.根据是台采用单根消融导管技术,将患者分为两组:(1)单导管组:76例,男27例、女49例,年龄(44.5±16.9)岁;RVOT-PVC 62例,RVOT-VT9例,RVlT-PVC 5例.(2)常规组:35例,男14例,女21例,年龄(46.7±16.5)岁;ROOT-PVC 29例,RVOT-VT4例,RVIT-PVC 2例.结果 两组均顺利完成消融术,未发生严重并发症.单导管组手术操作时间和X线曝光时间[(55.23±26.24)min和(9.93±5.32)min]较常规组[(68.37±21.83)min和(12.96±4.54)min]短(t:2.76和3.09,均P<0.01),手术费用(12440.32±761.24)元较常规组(22119.51±1071.07)元节省(t:46.09,P<0.001);其近、远期成功率分别为93.42%(71/76)、97.18%(69/71)与94.29%(33/35)、96.97%(32/33),差异无统计学意义,两组其他符项参数差异无统计学意义(P>0.05).结论 单导管射频消融治疗RVA安全、有效,操作简化,节省费用.     

Origin recognition complex harbors an intrinsic nucleosome remodeling activity

Eukaryotic DNA replication is initiated at multiple chromosomal sites known as origins of replication that are specifically recognized by the origin recognition complex (ORC) containing multiple ATPase sites. In budding yeast, ORC binds to specific DNA sequences known as autonomously replicating sequences (ARSs) that are mostly nucleosome depleted. However, nucleosomes may still inhibit the licensing of some origins by occluding ORC binding and subsequent MCM helicase loading. Using purified proteins and single-molecule visualization, we find here that the ORC can eject histones from a nucleosome in an ATP-dependent manner. The ORC selectively evicts H2A-H2B dimers but leaves the (H3-H4)₂ tetramer on DNA. It also discriminates canonical H2A from the H2A.Z variant, evicting the former while retaining the latter. Finally, the bromo-adjacent homology (BAH) domain of the Orc1 subunit is essential for ORC-mediated histone eviction. These findings suggest that the ORC is a bona fide nucleosome remodeler that functions to create a local chromatin environment optimal for origin activity.

DNA replication is a vital life process for all cell types—bacterial, eukaryotic, and archaeal. While there are important differences among the replication proteins of the three domains of life, they mostly function in similar ways. All of them use an origin binding protein that acts with other factors to load two hexameric helicases onto DNA for bidirectional unwinding of the duplex, and thus the ability to simultaneously replicate both strands of the cellular genome (1–3). The eukaryotic origin binding protein is a heterohexamer referred to as the origin recognition complex (ORC) (4). The sequences of the Orc1-6 subunits are conserved from yeast to human, and several of the subunits contain an adenosine triphosphate (ATP)-binding AAA⁺ module as in the Escherichia coli DnaA initiator. Origins in the budding yeast Saccharomyces cerevisiae occur in 100- to 200-bp DNA regions known as autonomously replicating sequences (ARSs) (5–10). However, the existence of ARSs is limited to only some species of budding yeast. Origins of replication with defined DNA sequences are not known at this time to exist in other eukaryotes (1, 2).The special feature of a defined origin sequence in S. cerevisiae has facilitated extensive characterization of the mechanism of DNA replication initiation (1). ORC interacts with Cdc6, Cdt1, and the minichromosome maintenance protein complex (Mcm)2–7 heterohexamer to assemble a Mcm2-7 double hexamer (referred to here as MCM DH) onto DNA in G1 phase (1–3). The loaded MCM DH is the “licensing” factor for replication because it acts as the marker for origin firing in S phase (11). Specifically, the MCM DH is acted upon by several initiation factors to form 2 larger 11-subunit CMG (Cdc45/Mcm2-7/GINS) helicases (12, 13). The two CMG helicases are oriented toward and pass each other to unwind DNA, and recruit the replicative machinery to form bidirectional replication forks (14, 15). ORC and the many other factors required to license an origin and form bidirectional replication forks are conserved in all eukaryotes.The yeast ARS is AT rich, which is not favorable to nucleosome binding (16, 17). Indeed, chromatin immunoprecipitation sequencing (ChIP-seq) studies indicate that many ARSs have a nucleosome-free region (NFR) that expands in G1/S phase (10, 18–20). Presumably the nucleosomes are moved aside to make way for ORC-mediated MCM DH formation at origins in G1 phase, and for CMG formation in S phase. In vitro studies demonstrate that in the presence of saturating nucleosomes, the ARS is functional for replication initiation without need for classic nucleosome remodelers (21), indicating that the expansion of the NFR at an ARS site may be achieved intrinsically by the origin recognition and replication machinery.We have recently reported that ORC binding to nucleosomes facilitates the loading of MCM DHs onto DNA, regardless of the DNA sequence (22). In that study, we observed the loss of the fluorescently labeled histone signal after ORC–nucleosome interaction, but did not investigate further the source and mechanism of this observation as it was not the focus of the study. Considering that ORC binding is the first step of origin licensing and that ORC harbors multiple ATPase sites, here, we explored the possibility that ORC itself may possess an ATP-facilitated nucleosome remodeling activity. Using single-molecule fluorescence microscopy combined with optical trapping, we find that ORC is indeed an ATP-dependent nucleosome remodeler with the ability to eject H2A-H2B dimers. ORC-mediated nucleosome remodeling may represent the inaugural event toward creating a local chromatin environment permissive to replication initiation.     

不同剂量卡维地洛防治高压负荷性心衰幼鼠心室重构

目的 观察不同剂量卡维地洛对高压负荷性心衰幼鼠心室重构的防治作用.方法 采用腹主动脉缩窄术建立慢性心力衰竭(CHF)模型,36只存活雄性5周龄Wistar幼鼠随机分组:(1)CHF对照组(n=8);(2)大剂量卡维地洛组(10 mg·kg-1·d-1,n=10);(3)中剂量卡维地洛组(1 mg·kg-1·d-1,n=10) ;(4)小剂量卡维地洛(0.1 mg·kg-1·d-1,n=8);另设假手术对照组.直接灌胃给药,给药4周后行高频超声、血流动力学、心脏病理分析、心肌细胞凋亡及其检测血清中脂质过氧化物(LPO)和超氧化物歧化酶(SOD)含量.结果 与假手术组比较,CHF组左室收缩末期内径(LVESD)、室间隔舒张末期厚度(IVSTd)、室间隔收缩末期厚度(IVSTs)、左室后壁舒张末期厚(LVPWTd)、左室后壁收缩末期厚度(LVPWTs)左、右心室相对重量(LVRW,RVRW)、收缩压(SBP)、舒张压(DBP)、左室收缩压(LVSP)、左室舒张末压(LVEDP) 、凋亡指数(AI) 、LPO均显著升高(P＜0.01),左室舒张末期内径LVEDD也明显升高(P＜0.05).左室短轴缩短率FS、左室射血分数EF、左室内压最大收缩率( dp/dtmax) 、左室内压最大舒张率(-dp/dtmax) 、SOD均显著降低(P＜0.01).与CHF组比较,卡维地洛组LVEDD、LVESD、IVSTd、IVSTs、LVPWTd、LVPWTs、LVRW、RVRW、SBP、DBP、LVSP、LVEDP、AI、LPO均呈剂量相关性下降,以大中剂量下降明显(P＜0.05或P＜0.01),FS、EF、 dp/dtmax、-dp/dtmax、SOD均显著升高(P＜0.01).结论 卡维地洛大、中、小剂量均能有效防治幼鼠CHF发展中的心室重构,改善血流动力学和心功能,阻止心肌细胞凋亡和清除氧自由基;小剂量有效,大剂量更佳.     

ST 段抬高心肌梗死急诊冠脉介入中室颤发生的分析

目的:分析ST 段抬高心肌梗死在急诊冠脉介入中发生室颤(VF)的临床特征和冠脉造影特点.方法:对50例接受急诊冠脉介入治疗的ST段抬高心肌梗死患者进行回顾性研究,根据术中有无室颤将患者分为两组,其中9例发生心室颤动(VF组),41例患者没有发生心室颤动(无VF组).比较两组的临床特征与冠脉造影的差异.结果:两组患者的基线特征相似.VF组冠脉内溶栓占33.3%,无VF组冠脉内溶栓2.4%,两组统计学上有显著性差异(P<0.05).VF组三支病变占77.7%,无VF组占33.3%,两组统计学上有显著性差异(P<0.05).结论:(1)在ST段抬高的心梗患者在急诊冠脉介入时室颤发生可能与冠脉内急性闭塞处血栓负荷有关.(2)在ST段抬高的心梗患者在急诊冠脉介入时室颤发生与冠脉病变严重程度有关.     

活血祛痰法逆转高血压左心室肥厚的实验研究

目的探讨活血祛痰治法逆转高血压左心室肥厚（ＬｅｆｔＶｅｎｔｒｉｃｕｌａｒＨｙｐｅｒｔｒｏｐｈｙ,ＬＶＨ）的作用机理。方法采用１４周龄自发性高血压大鼠（ＳｐｏｎｔａｎｅｏｕｓｌｙＨｙｐｅｒｔｅｎｓｉｖｅＲａｔ,ＳＨＲ）。观察采用活血祛痰治法及组方治疗前后大鼠血压（ＢｌｏｏｄＰｒｅｓｕｒｅ,ＢＰ）、左室重／体重（ＬｅｆｔＶｅｎｔｒｉｃｕｌａｒＭａｓｓ／ＢｏｄｙＷｅｉｇｈｔ,ＬＶＭ／ＢＷ）、左室壁相对厚度（ＬｅｆｔＶｅｎｔｒｉｃｕｌａｒＷａｌＴｈｉｃｋｎｅｓｓ,ＬＶＷＴ）、心肌Ｃａ２＋含量,以及心肌过氧化脂质（Ｌｉｐｉｄｐｅｒｏｘｉｄａｔｉｏｎ,ＬＰＯ）和超氧化物歧化酶活性（Ｓｕｐｅｒｏｘｉｄｅｄｉｓｍｕｔａｓｅ,ＳＯＤ）等的变化。结果１４周龄ＳＨＲ已形成ＬＶＨ,心肌Ｃａ２＋含量增高,心肌ＬＰＯ含量升高而ＳＯＤ活性下降。经活血祛痰治法及其组方治疗后,ＳＨＲ血压下降,ＬＶＨ明显消退,心肌Ｃａ２＋含量下降,心肌ＬＰＯ含量下降而ＳＯＤ活性升高。结论活血祛痰治法及其组方可逆转高血压ＬＶＨ,其作用机理与其降低血压和心肌Ｃａ２＋含量,改善心肌顺应性以及抗氧自由基损伤有关。     

梓醇促进局灶脑缺血大鼠皮质脊髓束芽生和重塑

目的观察梓醇对局灶脑缺血大鼠病灶对侧皮质脊髓束(corticospinal tract,CST)轴突芽生和重塑的影响。方法30只SD大鼠随机分为假手术组、模型组、生理盐水组、梓醇治疗组和胞磷胆碱对照组。开颅电凝右侧大脑中动脉,制备局灶永久性脑缺血模型,造模后24 h首次经腹腔注射梓醇(5 mg·kg-1)或胞磷胆碱(0.5 g·kg-1),每日1次,连续7d。采用黏贴物移除实验和足失误实验测试受累前肢(左前肢)功能状况;核磁共振(MRI)测量脑梗死体积;生物素化葡聚糖胺(biotinylated dextran amine,BDA)顺行示踪健侧CST,检测脊髓颈膨大区健侧CST越边至失神经支配侧的纤维数量,了解脊髓颈膨大区CST轴突重塑;免疫荧光双标脊髓颈膨大区BDA标记纤维与生长相关蛋白(growth-associatedprotein,GAP-43),检测BDA/GAP-43共定位信号,了解脊髓颈膨大区CST轴突芽生能力。结果造模后7、14、21和28d,梓醇组和胞磷胆碱组左前肢黏贴片移除时间均比模型组和生理盐水组明显缩短(P<0.05),左前肢失误率也较模型组和生理盐水组明显降低(P<0.05);其中,造模后28 d时,梓醇组左前肢感觉运动功能状况明显优于胞磷胆碱组(P<0.05)。造模后1和28 d,各组脑梗死体积差异无显著性(P>0.05)。造模后28 d,梓醇组脊髓颈膨大区健侧CST越边纤维占(8.5%±2.1%),较模型组(4.7%±1.3%)和胞磷胆碱组(5.5%±1.8%)明显增加(P<0.05);梓醇组脊髓颈膨大区BDA/GAP-43共定位信号明显强于模型组和胞磷胆碱组(P<0.05)。结论梓醇可增强缺血性脑卒中大鼠皮质脊髓束轴突芽生和重塑能力,有助于受累肢体感觉运动功能恢复。     

不同剂量氟伐他汀对慢性心力衰竭大鼠心肌组织血管紧张素Ⅱ和脑利钠肽水平影响的实验研究

目的 探讨不同剂量氟伐他汀对阿霉素诱导的慢性心力衰竭大鼠心肌组织血管紧张素Ⅱ(AngⅡ)和脑利钠肽(BNP)水平的影响. 方法将60只SD大鼠随机分为正常对照组、心力衰竭对照组、小剂量氟伐他汀组和大剂量氟伐他汀组,除正常对照组予0.9%氯化钠注射液腹腔注射外,余3组均采用阿霉素腹腔注射的方法建立慢性心力衰竭大鼠模型.模...     

培哚普利和坎地沙坦联合治疗原发性高血压左心室肥厚和颈动脉重塑疗效观察

目的探讨培哚普利和坎地沙坦联合治疗原发性高血压（EH）患者左心室肥厚（LVH）及颈动脉重塑的疗效。方法将142例伴LVH的EH患者随机分为培哚普利组（n=44）、坎地沙坦组（n=55）和联合治疗组（n=43）。设定目标血压值为收缩压（SBP）〈140mmHg和舒张压（DBP）〈90mmHg。3组患者分别口服起始剂量培哚普利4mg/d、坎地沙坦4mg/d和培哚普利4mg/d加坎地沙坦4mg/d。随访4周,若血压未能达标,则增加剂量,最大剂量为培哚普利8mg/d加坎地沙坦8mg/d。同时3组患者均口服氢氯噻嗪25mg/d,总疗程均为36周。检测治疗前后24h动态血压、心率（HR）、左室舒张末期内径（LVDd）、室间隔厚度（IVST）、左室舒张末期后壁厚度（LVPW）、左室质量指数（LVMI）和心胸比率（CTR）,检测颈动脉内膜-中膜厚度（IMT）、内径（ID）及IMT/ID。结果（1）3组治疗后24hSBP、24hDBP均分别较治疗前显著降低（P〈0.05）,而3组间比较差异无统计学意义（P〉0.05）;（2）3组治疗后LVDd、IVST、LVPW、LVMI、HR和CTR均分别较治疗前显著性降低（P〈0.05）,颈总动脉和颈内动脉IMT减小、ID增加、IMT/ID比值改善（P〈0.05或P〈0.01）,其中联合治疗组疗效最为显著（P〈0.05或P〈0.01）。结论培哚普利和坎地沙坦联合用药在逆转LVH、抑制心脏交感活性及改善颈动脉重塑方面较培哚普利或坎地沙坦单独用药具有更为显著的作用,且这些作用独立于降压疗效之外。