人右心室心外膜下细胞瞬间外向钾电流的初步研究

两例终末期心脏来源于心脏移植的受体病人 ,用酶解分离法获得心外膜下 (Epi)细胞 ,在全细胞钳制条件下观察人右心室Epi细胞瞬间外向钾电流 (Ito1 )的电生理特性。结果发现 :①Epi细胞具有强大的Ito1 ,在 0 .2Hz、+70mV和 37℃条件下 ,Epi细胞的峰值Ito1 离子流强度和密度分别达 1 940± 440pA、1 2 .9± 2 .6pA/pF ;②温度对Ito1 强度的影响明显 ,在 +70mV、0 .2Hz、2 2℃和 37℃条件下 ,Epi细胞峰值Ito1 强度和密度分别为 1 1 90± 31 0pA和 7.7±1 .8pA/pF、1 960± 465pA和 1 3 .1± 2 .8pA/pF ,差异有显著性 (P均 <0 .0 1 ) ;③Epi细胞Ito1 离子流强度表现出明显的频率依赖性 ,在 37℃和 +70mV、刺激频率分别为 0 .2 ,0 .5 ,1和 2Hz时 ,Epi细胞Ito1 离子流强度分别为 1 91 0±42 0 ,1 660± 360 ,1 4 1 0± 2 50 ,830± 1 4 0pA ,差异均有显著性 (P均 <0 .0 1 )。结论 :人右心室Epi细胞存在强大的Ito1 ,此为人右心室Epi细胞复极 1期一个突出的电生理特点 ,可能是Brugada综合征等疾病所致恶性心律失常的重要离子基础之一。     

人右心室瞬间外向钾电流电不均一性的初步研究

目的探讨人右心室复极1相瞬间外向钾电流(Ito)的跨壁电不均一性。方法应用全细胞钳制技术,对人右心室心外膜下(Epi)细胞、中间层(M)细胞和心内膜下(Endo)细胞复极1相Ito离子流的电流强度、密度和动力学过程进行研究。结果人右心室三层细胞之间存在明显的Ito离子流电不均一性,在37℃、0·2Hz和除极化试验电压为+70mV时,Epi细胞和M细胞峰值Ito离子流的密度分别为(13·2±2·6)pA/pF,和(8·9±3·1)pA/pF,远大于Endo细胞(2·7±0·35)pA/pF,(P<0·01);在37℃条件下,人右心室Epi细胞和M细胞Ito离子流的激活和失活过程符合Boltzmann分布,两组细胞的激活和失活V1/2、斜率因子K等均差异无统计学意义(P>0·05)。结论在人右心室跨越室壁的3层细胞间,特别是Epi细胞与Endo细胞之间、M细胞与Endo细胞之间,复极1相存在明显的Ito离子流强度差异和强大的Ito离子流梯度。     

急性心肌梗死后一周对心室肌细胞瞬间外向钾电流的影响

研究急性心肌梗死 (AMI)心室肌细胞瞬间外向钾电流 (Ito)的变化。采用结扎兔冠状动脉左前降支的方法建立AMI动物模型 ,应用膜片钳全细胞记录方法 ,研究AMI后 1周心外膜梗死区心肌细胞Ito的变化。结果 :正常对照组 (n =16 )心肌细胞在 - 30mV激活 ,心肌梗死 (简称心梗 )组细胞在 - 2 0mV激活 ,均呈线性电压依赖性。心梗组梗死区细胞 (n =12 )Ito的电流密度明显下降 ,I V曲线明显下移。心梗组Ito电流密度 (去极化电位 +6 0mV时 )明显低于对照组 (7.4 7± 2 .39vs 17.39± 5 .2 4pA/pF ,P <0 .0 1)。结论 :AMI可引起心室肌细胞Ito电流密度下降 ,导致梗死区细胞动作电位平台期相对延长 ,复极异常 ,造成心肌细胞之间动作电位及不应期离散度增大 ,容易形成折返 ,此可能是导致心肌梗死后出现折返性室性心律失常的原因。     

犬右室瞬间外向钾电流异质性的研究

应用全细胞钳制技术对犬右室心外膜下 (epi)细胞、中层 (M)细胞和心内膜下 (endo)细胞复极 1期瞬间外向钾电流 (Ito1)的强度、密度和动力学过程进行系统定量研究 ,以期从复极 1期主要离子流的角度 ,探讨右室复极 1期跨越室壁的电异质性。结果发现 :犬右室epi细胞和M细胞存在强大的Ito1离子流 ,在刺激频率为 0 .2Hz、37℃和去极化试验电压为 +70mV时 ,epi细胞和M细胞峰值Ito1离子流的强度分别为 46 5 0± 176 0 ,36 2 0± 1880pA ,其激活和失活动力学过程符合Boltzmann分布。与epi细胞和M细胞相比 ,endo细胞Ito1离子流微小 ,同样条件下其平均峰值Ito1离子流仅为 480± 130pA。表明在右室跨越室壁的三层细胞间 ,特别是epi细胞与endo细胞之间、M细胞与endo细胞之间 ,复极 1期存在明显的Ito1离子流强度差异和强大的Ito1离子流梯度 ,此为右室电异质性的一种突出表现 ,它可能是Brugada综合征等疾病所致恶性心律失常的重要离子基础之一     

BmkTXK β对家兔心房肌细胞钾电流的影响

为研究东亚钳蝎毒素BmkTXKβ对家兔心房肌单细胞电生理特征的影响 ,应用全细胞膜片钳技术记录各项钾电流和动作电位。结果 :BmkTXKβ呈浓度依赖性地延长动作电位时程 (APD2 0 、APD50 和APD90 ) ,但对动作电位幅度 (APA) ,静息膜电位 (RMP)和 0相最大除极速度 (Vmax)无明显影响 (n =9)。在刺激电压 +5 0mV时 1μmol/L的BmkTXKβ使心房肌细胞瞬间外向钾电流 (Ito)从 13.6 3± 0 .87pA/pF减少到 7.98± 0 .78pA/pF ,抑制率为 41.4%(n=10 ,P <0 .0 1)。同时 ,这种作用具有显著的浓度依赖性 ,抑制 5 0 %的电流所需浓度 (IC50 )的均值为 0 .95 μmol/L。BmkTXKβ可抑制延迟整流性钾电流 (IK) ,表现为剂量依赖性阻断的形式。 10 μmol/L时 (刺激电压 +70mV) ,它对IK的抑制率为 39.3 %(从 5 .86± 0 .6 4pA/pF降到 3 .5 6± 0 .5 8pA/pF ,n =6 ,P <0 .0 5 )。IC50 的均值为 2 .76 μmol/L。但BmkTXKβ对内向整流钾电流 (IK1)的电流幅值及其反转电位基本无影响 (n =6 ,P >0 .0 5 )。结论 :BmkTXKβ阻断Ito和IK 等与心脏复极相关的钾离子通道 ,且能在多个环节显著延长APD。     

胺碘酮对模拟缺氧状态下大鼠心室肌细胞瞬时外向和内向整流钾电流的影响

目的通过观察胺碘酮对模拟缺氧状态下急性分离的大鼠心室肌单细胞复极相中瞬时外向钾电流(Ito)和内向整流钾电流(IK1)通道的影响,探讨其在该条件下抗心律失常的作用机制。方法使用酶解法分离获取大鼠单个心室肌细胞,通过持续通以模拟缺氧细胞外液建立体外模拟缺氧模型,采用全细胞膜片钳实验技术研究胺碘酮对该条件下Ito和IK1的作用。结果胺碘酮呈剂量依赖性降低Ito和IK1电流幅值,对Ito抑制效应的起始浓度为1μmol/L,100μmol/L时抑制作用达最大,最大抑制幅度为56.78%±4.27%(23.98±2.18pA/pFvs10.38±4.27pA/pF;测试电压为+70mV;P<0.01;n=5),IC50(半数抑制浓度)为74.35μmol/L,但Ito的I-V曲线趋势并没有发生变化,稳态激活和失活曲线几乎不发生移动。胺碘酮对IK1内向电流部分抑制起始浓度为1μmol/L,外向电流部分抑制效应的起始浓度为2μmol/L,其最大抑制幅度分别为58.77%±10.76%(56.32±7.24pA/pFvs23.22±7.30pA/pF;测试电压为-150mV;P<0.01)和33.29%±2.15%(6.70±0.89pA/pFvs4.46±0.93pA/pF;测试电压为+40mV;P<0.01;n=5)。对内向电流成分的IC50为63.75μmol/L,IK1通道的稳态激活曲线无明显改变。结论在大鼠离体心室肌单细胞模拟缺氧条件下,胺碘酮对Ito和IK1电流幅度呈剂量依赖性抑制,有对抗缺氧本身造成的动作电位时程缩短效应;对I内向电流成分的敏感性高于外向成分。     

自发性高血压大鼠左心室肌细胞动作电位延长的离子机制

目的:研究自发性高血压大鼠(SHR)左心室肌细胞动作电位时程延长的膜离子流基础.方法:应用酶解方法分离获得正常血压Wistar大鼠和SHR的左心室肌细胞,采用玻璃微电极技术记录动作电位,膜片钳全细胞记录膜离子流,对比正常心室肌细胞和肥大心室肌细胞间动作电位及膜离子流差别.结果:(1)SHR和Wistar大鼠的心脏/体重比分别为5.66±0.46 mg/g和3.7±0.29 mg/g (P<0.001) ,细胞平均膜电容分别为280.68±67.98 pF 和189.94±56.59 pF(P<0.05).提示SHR 心脏肥厚、心肌细胞增大;(2)SHR动作电位APD50和APD90较Wistar大鼠明显延长(21.33±1.56 ms vs 14.91±2.95 ms,P<0.001; 164.6±74 ms vs 93.27±10.59 ms,P<0.00 1),说明SHR心室肌细胞存在复极延迟;(3)SHR的平均ICa-L幅值显著大于Wistar大鼠,分别为1944±466.8 pA和1136±33.3 pA(P<0.001),电流密度二者间无差异(6.932±1.7 1 pA/pF vs 6.19±2.85 pA/pF) ,但SHR的慢失活时间常数明显延长(56.01±13.36 ms vs 43.63±17.89 ms,P<0.001);(4)S HR的Ik1内向电流密度显著小于Wistar大鼠(11.3±2.26 pA/pF vs 14.33 pA/pF,P<0.05),外向电流密度二者间差异无显著性(2.36±0.86 pA/pF vs 2.96±1.27 pA/pF);(5)SHR的Ik密度与Wista r大鼠间无差别(12.38±5.46 pA/pF vs 11.86±3.59 pA/pF);(6)SHR的Ito密度显著地低于Wistar 大鼠(+70 mV时, 8.21±6.64 pA/pF vs 19.16±6.17 pA/pF, P<0.001).但通道的激活和失活时间常数二者无差异,提示Ito的降低可能仅是通道数减少所致.结论:SHR左心室肌细胞动作电位时程延长系外向复极钾流(Ito、Ik1)减小和慢钙通道失活时间常数延长所致.     

兔冠状动脉结扎1小时缺血区心室肌细胞瞬间外向钾通道的变化

为探讨在急性心肌梗死 (AMI)早期瞬间外向钾通道的变化及其在室性心律失常发生中的作用 ,以开胸冠状动脉 (简称冠脉 )结扎法制备兔急性心肌缺血模型 ,1h后处死动物分离心室肌细胞 ,采用全细胞膜片钳记录技术观察缺血区心外膜心室肌细胞瞬间外向钾通道电流 (Ito)的变化 ,以正常心肌Ito为对照。结果 :急性冠脉结扎 1h兔缺血区心室肌细胞Ito受到抑制 ,电流密度$C电压关系曲线下移 ,测试电压 + 60mV时的Ito电流密度对比显示 :对照组为 1 7.39± 5 .2 4pA/pF (n =1 2 ) ,冠脉结扎 1h组为 7.75± 3.1 1pA/pF (n =1 0 ) ,与对照组相比下降了 5 7% ,P <0 .0 0 1 ;其失活曲线左移 ,半数最大失活电压 (V1 /2 )对照组为 - 35 .2± 5 .3mV(n =1 2 ) ,冠脉结扎 1h组为 - 5 5 .1± 5 .6mV(n =1 0 ) ,与对照组比较失活速度加快 ,P <0 .0 1 ;冠脉结扎后 1h组Ito恢复明显减慢 ,恢复时程延长 ,P <0 .0 5。结论 :冠脉结扎后 1h缺血区心室肌细胞瞬间外向钾通道受抑制 ,影响动作电位复极 ,容易诱发 2相折返 ,可能为AMI后室性心律失常发生的机制之一。     

西洛他唑对大鼠右心室肌细胞瞬间外向钾电流的影响

目的 :观察西洛他唑对大鼠右心室肌细胞瞬间外向钾电流 (Ito1)的影响 ,探讨西洛他唑抗心律失常作用的确切机制。方法 :酶解法分离SD大鼠右心室肌细胞 ,采用全细胞膜片钳技术记录右心室肌细胞Ito1。结果 :5 0 μmol/L西洛他唑显著降低Ito1,使Ito1幅值由加药前 (12 .7± 0 .5 ) pA/ pF降至 (7.6± 0 .4 ) pA/ pF ,降低 (4 0 .1± 3.0 ) % (P <0 .0 1,n =9)。在 1～ 5 0 μmol/L范围内 ,西洛他唑的作用呈浓度依赖性 ,半抑制浓度为 (17.2±2 .2 ) μmol/L。此外 ,该药对Ito1电压依赖性的激活和失活曲线无显著影响。结论 :西洛他唑浓度依赖性地阻滞大鼠右心室肌细胞的Ito1。     

奎尼丁对正常大鼠心室肌细胞瞬间外向钾电流的影响

研究大鼠心室肌细胞瞬间外向钾电流(Ito1)的特性及奎尼丁对其的影响,从而从细胞离子的层面去探讨奎尼丁作为治疗Brugada综合征的侯选药物的机制。用酶解法分离大鼠单个左室细胞,应用膜片钳全细胞方法记录Ito1,观察不同浓度的奎尼丁对心室肌细胞Ito1的作用。结果:①大鼠心室肌细胞具有强大的Ito1,在0.2Hz,+70mV和32℃条件下,其平均峰值Ito1强度和密度分别为1940±440pA和12.9±2.6pA/pF;②在奎尼丁1,2.5,5,7.5,10μmol/L不同的浓度下,奎尼丁抑制Ito1程度越明显(自身对照P<0.05),其作用呈浓度依赖性。结论:奎尼丁可以通过抑制Ito1,延长动作电位的复极时程,此很有可能是其作为治疗Brugada综合征的侯选药物的机制之一。     

Research and Evaluation of the Influence of the Construction of the Gate and the Influence of the Piston Velocity on the Distribution of Gases into the Volume of the Casting

Distribution of gasses to the cast volume and volume of pores can be maintained within the acceptable limits by means of correct setting of technological parameters of casting and by selection of suitable structure and gating system arrangement. The main idea of this paper solves the issue of suitability of die casting adjustment—i.e., change of technological parameters or change of structural solution of the gating system—with regards to inner soundness of casts produced in die casting process. Parameters which were compared included height of a gate and velocity of a piston. The melt velocity in the gate was used as a correlating factor between the gate height and piston velocity. The evaluated parameter was gas entrapment in the cast at the end of the filling phase of die casting cycle and at the same time percentage of porosity in the samples taken from the main runner. On the basis of the performed experiments it was proved that the change of technological parameters, particularly of pressing velocity of the piston, directly influences distribution of gasses to the cast volume.     

Weighing the QT Intervals with the Slope or the Amplitude of the T Wave

Objective: The reproducibility of QT interval measurements is low, even for the mean QT interval based on the standard ECG. In this study we analyzed whether the reproducibility of the mean weighed QT interval was better than the simple mean QT interval. The weighing was based on the amplitude of the T wave or the slope of the steepest tangent on the terminal part of the T wave. Material and methods: 12‐lead ECGs of 130 postmyocardial infarction patients were obtained. The QT intervals were measured by the tangent‐method on two occasions by the same observer Mismatch QT intervals were defined as QT intervals that were measured at only one occasion. Sixteen ECGs were rejected. The data were split into 34 and 80 ECGs for optimization and validation of the weighing, respectively. The weighed QT dispersion was calculated as the weighed mean of the three longest minus the weighed mean of the three shortest QT intervals. Results: Weighing with the slope increased the reproducibility by 41% (P = 3 10^‐6), but weighing with the amplitude reduced it by 20% (P = 0.02). However, if measurements with errors above 75 ms were rejected, weighing with the slope or the amplitude increased the reproducibility with 26% and 20% (P = 0.02), respectively. Weighing did not change the reproducibility of the weighed QT dispersion. Conclusion: Weighing with the slope improved the reproducibility of the mean weighed QT interval. However, if measurements with errors above 75 ms were rejected, weighing with the amplitude also increased the reproducibility. Weighing did not change the reproducibility of the weighed QT dispersion. Weighing is particularly efficient at reducing the negative impact of mismatch QT intervals on the reproducibility. A.N.E. 2002;7(1):4–9     

县级以下综合医疗机构医务人员对现代结控知识的认识现状调查

目的本文旨在了解医务人员现代结控知识掌握的现状及培训效果?方法于培训前后进行问卷调查,内容包括:病例发现?结核病诊断及化疗?结果培训前疫情报告和转诊,回答正确者占75.2%?71.7%;对临床表现?查痰和诊断依据,回答正确者占83.5%?42.5%?40.8%;抗痨药物?用药方法?化疗原则?短化方案?短化疗程?治愈标准六项,回答正确者占58%?14.4%?20.8%?9.2%?17%?24.3%?培训后再次调查发现,90%以上医务人员对现代结控基本知识已掌握?结论各级医务人员现代结控知识是很贫乏的,因此,对其进行系统培训是极为必要的,此项工作省时?省力?投入少,可收到事半功倍的效果。     

大骨节病病区水,粮实验对动物的骨和软骨中化学元素组成的影响

用质子激发 X 线荧光分析方法(PIXE)测定了大骨节病病区和非病区的水、粮以及用该水粮喂养的大白鼠的肋软骨和硬骨中22种化学元素的含量。结果发现水粮中存在差异的元素反应在用该水粮喂养的大白鼠的骨、软骨中也存在差异,含量都低的元素有 P、Mn、Cu、As、Zn。都高的有铅。其中锌低在水、粮、硬骨和软骨中都完全一致呈非常显著性差异(p<0.01)。提示病区水、粮中化学元素对骨质的影响不是单一元素缺乏或过多所致,而是多种元素的复合因素。     

Assessment of the Soft-Tissue Seal at the Interface between the Base of the Fixed Denture Pontic and the Oral Mucosa

Fixed dentures (bridges) are often selected as a treatment option for a defective prosthesis. In this study, we assess the contact condition between the base of the pontic and oral mucosa, and examine the effect of prosthetic preparation and material biocompatibility. The molars were removed and replaced with experimental implants with a free-end type bridge superstructure after one week. In Experiment 1, we assessed different types of prosthetic pre-treatment: (1) the untreated control group (Con: mucosa recovering from the tooth extraction); (2) the laser irradiation group (Las: mucosa recovering after the damage caused by a CO₂ laser); and (3) the tooth extraction group (Ext: mucosa recovering immediately after the teeth extraction). In Experiment 2, five materials (titanium, zirconia, porcelain, gold-platinum alloy, and self-curing resin) were placed at the base of the bridge pontic. Four weeks after the placement of the bridge, the mucosa adjacent to the pontic base was histologically analyzed. In Experiment 1, the Con and Las groups exhibited no formation of an epithelial sealing structure on the pontic base. In the Ext group, adherent epithelium was observed. In Experiment 2, the sealing properties at the pontic interface were superior for titanium and the zirconia compared with those made of porcelain or gold-platinum alloy. In the resin group, a clear delay in epithelial healing was observed.     

高胆红素血症对肿瘤标志物测定的影响探讨

目的探讨高胆红素血症对Ca19-9、Ca24-2和CEA检测的影响.方法对320例胆管、胆囊良恶性疾病病人,15例胆囊炎病人的胆汁和血清以及10例肝硬化、10例黄疸肝炎病人进行Ca19-9、Ca24-2和CEA检测.结果在良性胆管、胆囊疾病中,Ca19-9的假阳性最高;在胆红素增高的良性疾病中,Ca19-9假阳性率达46.7%;15例胆汁和血清以及10例肝硬化和10例黄疸肝炎病人中,Ca19-9的假阳性率分别为93%、20%、80%和80%.结论高胆红素血症对Ca19-9检测影响最明显,胆囊、胆管良恶性疾病鉴别时,以Ca24-2和CEA检测为佳.     

Echocardiography in the Emergency Department: From the Perspective of the Emergency Physician and the Cardiologist

Echocardiography performed in the emergency department must adapt to this new setting for noninvasive diagnostic testing. Emergency physicians require echocardiography to provide rapid diagnosis in life-threatening emergencies. New initiatives are being proposed by emergency physicians in the delivery of this test. Cardiologists now use echocardiography in the emergency-department to make the diagnosis of heart disease earlier and with greater accuracy.     

Tracing the protectors path from the germ line to the genome

One of the basic principles that nature uses in evolution is to recycle successful concepts and create new functions by modifying existing units. This conservatism in evolution has resulted in an astonishingly high sequence identity of genes, even between evolutionarily distant species such as the nematode Caenorhabditis elegans and Homo sapiens. The recycling of successful concepts in conjunction with gene duplication events has also led to the existence of highly homologous proteins within the genome of many species. Often, these homologous proteins show similar, yet distinct functions that, in combination with their individual tissue distribution, define their specific physiological role. One prominent example is the p53 protein family, which consists of p53, p63, and p73. Recent advances in understanding the specific biological functions of these members have shed some light onto the evolution of this crucial protein family, from a germ line-specific quality-control factor to a somatic tumor suppressor. Furthermore, structures of the oligomerization domains of the mammalian paralogs, p53 and p73, and invertebrate orthologs, CEP-1 and DMP53, have delineated evolutionary changes and revealed that the oligomerization domain of p53 lacks additional stabilizing structural elements present in all other p53 family members. This suggests that p53 is the most recent evolutionary member of this protein family and predicts a mechanism for p53 activation.