肥厚型心肌病患者超极化激活环核苷酸门控阳离子通道mRNA的表达

目的探讨肥厚型心肌病患者超极化激活环核苷酸门控阳离子通道(HCN4)的表达。方法构建重组质粒,用梯度稀释的质粒模板建立SYBRGreen荧光定量逆转录-聚合酶链式反应(RT-PCR)法检测HCN4的标准曲线,利用建立的RT-PCR体系对肥厚型心肌病和正常心肌组织标本的左室HCN4mRNA进行检测。结果成功构建了质粒重组子,并建立用SYBRGreen荧光染料在RNA水平检测HCN4通道的标准曲线。HCN4通道在肥厚型心肌病中的表达水平高于正常心肌。结论肥厚型心肌病患者HCN4mRNA的表达较正常人增高。     

犬库布病毒SYBR GreenⅠ实时荧光定量PCR检测方法的建立及应用北大核心CSCD

目的建立可检测狐狸物种中犬库布病毒(CaKoV)的SYBR GreenⅠ实时荧光定量PCR检测方法。方法利用PCR方法扩增狐狸CaKoV的3D基因504bp,将其克隆到pEASY-Blunt载体,构建重组质粒作为阳性质粒,以其为模板建立SYBR GreenⅠ实时荧光定量PCR检测方法,验证其灵敏度、特异性和重复性。结果建立的SYBR GreenⅠ实时荧光定量PCR检测方法检测目的基因在6.12×10^(1)~6.12×10^(8)拷贝/μl时呈良好的线性关系,相关系数为0.994,斜率为-4.369,灵敏度6.12×10^(1)拷贝/μl。该方法对于CPV、CDV和CCV未出现特异性扩增。所有标准曲线在溶解温度为86.49℃时出现单一的特异峰。使用本方法检测2021年辽宁、山东地区的253份狐狸临床标本,总阳性率为7.91%。结论建立的CaKoV SYBR GreenⅠ实时荧光定量PCR方法敏感、特异,用于狐狸CaKoV感染的快速检测。     

SYBR Green荧光PCR检测美洲钩虫方法的建立

目的建立荧光定量PCR检测美洲钩虫的方法。方法提取虫体基因组DNA、根据GenBank中美洲钩虫ITS 2序列设计特异引物,PCR扩增ITS 2序列、克隆、测序和比对。常规PCR检验引物特异性。将ITS 2序列扩增产物回收、纯化后经T克隆转入大肠埃希菌DH5α,提取重组质粒,鉴定后作为标准品模板建立荧光定量PCR标准曲线,并做灵敏性和重复性试验。结果构建的荧光定量PCR标准曲线循环阈值与模板浓度呈良好的线性关系,溶解曲线的吸收峰单一,实验重复性良好。结论成功构建了SYBR Green I荧光定量PCR检测美洲钩虫的方法,可用于快速、准确、定量检测美洲钩虫。     

基因Ⅲ型乙型脑炎病毒Real-time PCR检测方法的建立及应用

目的建立针对云南地区流行的基因Ⅲ型乙型脑炎病毒株Real-time PCR检测方法。方法根据云南地区分离株乙型脑炎病毒株(Yunnan0901)基因组核苷酸序列设计特异性引物,构建pMD18-T-JEV-E质粒,以此为模板进行SYBR GreenⅠReal-time PCR扩增并制作标准曲线,摸索最佳反应体系条件,建立乙型脑炎病毒荧光定量PCR检测方法,并与普通RT-PCR方法相比较。结果建立的SYBR GreenⅠReal-time PCR标准曲线呈现良好的重复性和特异性,与模板浓度呈现良好的线性关系。与RT-PCR方法相比,SYBR GreenⅠReal-time PCR的灵敏度高10倍,而且不与猪瘟病毒、猪蓝耳病毒、猪圆环病毒、基孔肯雅病毒、辛德毕斯病毒核酸发生非特异性扩增,具有良好的特异性。用该方法检测云南部分地区的蚊虫样品,其中库蚊、按蚊乙型脑炎病毒阳性率分别为17.4%和30.7%,且主要为基因型Ⅲ型。结论本实验建立的检测基因Ⅲ型乙型脑炎病毒的SYBR GreenⅠReal-time PCR方法具有特异、敏感、快速、定量、重复性好等特点,可应用于乙型脑炎疫情的监测。     

基因Ⅲ型乙型脑炎病毒Real-time PCR检测方法的建立及应用北大核心CSCD

目的建立针对云南地区流行的基因Ⅲ型乙型脑炎病毒株Real-time PCR检测方法。方法根据云南地区分离株乙型脑炎病毒株(Yunnan0901)基因组核苷酸序列设计特异性引物,构建pMD18-T-JEV-E质粒,以此为模板进行SYBR GreenⅠReal-time PCR扩增并制作标准曲线,摸索最佳反应体系条件,建立乙型脑炎病毒荧光定量PCR检测方法,并与普通RT-PCR方法相比较。结果建立的SYBR GreenⅠReal-time PCR标准曲线呈现良好的重复性和特异性,与模板浓度呈现良好的线性关系。与RT-PCR方法相比,SYBR GreenⅠReal-time PCR的灵敏度高10倍,而且不与猪瘟病毒、猪蓝耳病毒、猪圆环病毒、基孔肯雅病毒、辛德毕斯病毒核酸发生非特异性扩增,具有良好的特异性。用该方法检测云南部分地区的蚊虫样品,其中库蚊、按蚊乙型脑炎病毒阳性率分别为17.4%和30.7%,且主要为基因型Ⅲ型。结论本实验建立的检测基因Ⅲ型乙型脑炎病毒的SYBR GreenⅠReal-time PCR方法具有特异、敏感、快速、定量、重复性好等特点,可应用于乙型脑炎疫情的监测。     

SYBR Green Ⅰ实时荧光定量PCR检测BMI-1 mRNA方法的建立

目的 建立SYBR Green Ⅰ实时荧光PCR定量检测人类BMI-1 mRNA的方法.方法 以含有目的基因BMI-1 cDNA的质粒pEGFP-BMI-1为阳性模板,进行纯化和定量及系列稀释,应用SYBR Green Ⅰ实时荧光定量PCR检测BMI-1,建立标准曲线,熔解曲线分析产物的特异性.结果 该法检测的线性范围为6.4×101～6.4×107拷贝,相关系数r为-1.00,6.4×103拷贝/反应的标本批内变异系数(CV)和日间CV分别为1.6%和2.8%.熔解曲线分析显示单一的峰,Tm为(80.40±0.18)℃.结论 SYBR Green Ⅰ实时荧光PCR定量检测BMI-1 mRNA是快速有效、灵敏度高、特异性好的方法,可为BMI-Ⅰ的进一步研究奠定基础.     

内参照基因在实时荧光定量RT-PCR检测中的应用

目的 建立测定内参照β-actin表达量的实时荧光定量RT-PCR两步法检测方法.方法 根据Genbank 中人β-actin保守区域序列设计荧光PCR适用的引物和探针,构建质粒标准品建立标准曲线用于荧光PCR相对定量,检测荧光PCR方法的特异性和重复性.结果 建立了人β-actin实时荧光RT-PCR检测方法.结论 本实验建立的人β-actin表达实时荧光RT-PCR两步法检测方法特异性和重复性较好,为β-actin作为定量RT-PCR中内参照基因进行人其他功能基因和病原基因表达的定量分析奠定了基础.     

SYBRGreenⅠ染料法定量PCR用于人体疟原虫定量检测及虫种鉴别的研究

目的 建立一种可用于疟原虫检测并同时鉴别虫种的荧光定量PCR方法.方法 根据人体疟原虫18SrRNA基因序列特征,在疟原虫种特异性区域两侧的属特异性保守区设计引物,对4种人体疟原虫进行PCR扩增,将得到的扩增产物采用TA克隆法插入pGEM-T载体制备标准质粒,用于制备标准曲线进行定量分析,并进行熔解曲线分析,测定各虫种扩增产物的熔解温度.结果 4种人体疟原虫均能扩增得到特异性片断,荧光定量PCR方法中建立的标准曲线相关关系较好(相关系数r =-1.00),熔解曲线分析结果显示,4种人体疟原虫的熔解温度相差较大,分别为三日疟原虫71.3℃、恶性疟原虫72.8℃、卵形疟原虫74.6℃和间日疟原虫75.8℃.结论 建立的SYBR Green Ⅰ染料法荧光定量PCR技术可同时进行人体疟原虫的定量检测和虫种鉴别.     

SYBR Green Ⅰ实时荧光定量PCR检测BMI-1 mRNA方法的建立

目的 建立SYBR Green I实时荧光PCR定量检测人类BMI-1 mRNA的方法。方法 以含有目的基因BMI-1 cDNA的质粒pEGFP-BMI-1为阳性模板,进行纯化和定量及系列稀释,应用SYBR Green I实时荧光定量PCR检测BMI-1,建立标准曲线,熔解曲线分析产物的特异性。结果 该法检测的线性范围为6.4×10^1～6.4×10^7拷贝,相关系数r为-1.00,6.4×10^3拷贝/反应的标本批内变异系数（CV）和日间CV分别为1.6%和2.8%。熔解曲线分析显示单一的峰,Tm为（80.40±0.18）℃。结论 SYBR Green I实时荧光PCR定量检测BMI-1 mRNA是快速有效、灵敏度高、特异性好的方法,可为BMI-1的进一步研究奠定基础。     

狂犬病病毒荧光定量RT—PCR检测方法的建立与初步应用

目的建立狂犬病病毒快速检测法。方法根据狂犬病病毒核蛋白基因的保守序列分别设计两对引物及其相应的TaqMan探针。构建pMD-N重组质粒,建立荧光定量RT-PCR绝对定量标准品,并对反应体系进行优化,建立绝对定量的标准曲线。利用10倍稀释法检验方法的灵敏度并与普通RT-PCR法进行比较;作重复性和特异性检验后进行临床标本的检测。结果构建了绝对定量的参照质粒,标准曲线相关系数为0.998。狂犬病病毒荧光定量RT-PCR检测反应的灵敏度为10个TCID_(50);5种非狂犬病病原体检测均为阴性。结论建立的狂犬病病毒的荧光定量RT- PCR检测方法快速、特异性强、灵敏度高、稳定性好,可以应用于临床样品的检测。     

Sinus node dysfunction and hyperpolarization-activated (HCN) channel subunit remodeling in a canine heart failure model

BACKGROUND: The hyperpolarization-activated cation current I(f) contributes significantly to sinoatrial node pacemaker function and possibly to ectopic arrhythmogenesis. Little is known about the expression of corresponding hyperpolarization-activated cyclic nucleotide-gated (HCN) channel subunits in normal hearts and HCN remodeling by diseases, like congestive heart failure (CHF), associated with disturbances of cardiac rhythm. METHODS AND RESULTS: We assessed expression of HCN1, 2 and 4 in normal mongrel dogs and dogs subjected to 2-week ventricular tachypacing-induced CHF. Competitive RT-PCR, Western blot and immunohistochemistry were used to quantify HCN subunit mRNA and protein expression in the right atrium (RA) and sinoatrial node. CHF approximately doubled sinus node recovery time, indicating suppressed sinus node pacemaker function. HCN expression under control conditions was HCN4 > HCN2 > HCN1. HCN2 and HCN4 expression was greater at both protein and mRNA levels in sinoatrial node than RA. CHF significantly decreased sinus node HCN expression at both mRNA and protein levels (HCN2 by 78% and 82%; HCN4 by 42% and 77%, respectively). RA HCN2 expression was unaltered by CHF, but HCN4 was significantly upregulated (by 209%). CONCLUSIONS: HCN4 is the dominant subunit in canine sinoatrial node and RA; strong sinus node HCN expression likely contributes to its pacemaker function; downregulation of HCN4 and HCN2 expression contribute to CHF-induced sinus node dysfunction; and upregulation of atrial HCN4 may help to promote atrial arrhythmia formation. These findings provide novel information about the molecular basis of normal and disease-related impairments of cardiac impulse formation.     

乳鼠窦房结细胞原代培养方法的优化

目的：对乳鼠窦房结细胞原代培养方法进行改进,并观察超极化激活环核苷酸门控阳离子通道（HCN4）在心脏细胞上的表达特点. 方法：取新生SD乳鼠的窦房结组织,在传统乳鼠窦房结细胞原代培养方法的基础上进行优化改进,选用0.1％胰蛋白酶与0.1％Ⅱ型胶原酶按照1∶1制成的混合消化酶,以减少窦房结自律细胞的损伤,混合酶消化后采用差速贴壁法及5-溴脱氧尿嘧啶核苷（5-Brdu）纯化处理.通过免疫荧光实验观察HCN4在乳鼠心脏细胞上的表达情况. 结果：（1）本方法培养的心脏细胞存活率为95.8％.（2）经差逮贴壁、5-Brdu处理,窦房结细胞所占比例明显提高.（3）培养3～5 d,视野中绝大多数为搏动的心脏细胞,成纤维细胞无明显增殖,可观察到梭形、三角形和不规则形3种细胞.其中梭形细胞所占比例最高,其细胞器不发达,糖原颗粒不丰富,肌原纤维较少,搏动频率最快,表达HCN4;三角形细胞微量表达HCN4. 结论：（1）混合消化酶结合差速贴壁及5-Brdu处理,可以显著提高细胞成活率及窦房结梭形细胞的比例,是可靠的窦房结细胞的分离纯化方法.（2）搏动频率快、细胞器不发达、糖原颗粒少、HCN4表达阳性的梭形细胞可能就是窦房结的起搏细胞.     

Extended atrial conduction system characterised by the expression of the HCN4 channel and connexin45

OBJECTIVE: In the heart, there are multiple supraventricular pacemakers involved in normal pacemaking as well as arrhythmias and the objective was to determine the distribution of HCN4 (major isoform underlying the pacemaker current, I(f)) in the atria. METHODS: In the atria of the rat, the localisation of HCN4 and connexins was determined using immunohistochemistry, and electrical activity was recorded using extracellular electrodes. RESULTS: As expected, HCN4 and Cx45 (but not Cx43) were expressed in the sinoatrial node extending from the superior vena cava down the crista terminalis. The same pattern of expression of HCN4 and connexins was observed in a novel tract of nodal-like cells extending from the superior vena cava down the interatrial groove. Although the sinoatrial node was usually the leading pacemaker site, the novel tract of HCN4-expressing cells was capable of pacemaking and could act as the leading pacemaker site; there was evidence of a hierarchy of pacemakers. The same pattern of expression of HCN4 and connexins was also observed in the atrioventricular ring bundle (including the atrioventricular node) encircling the tricuspid valve, but not in the atrioventricular ring bundle encircling the mitral valve. HCN4 was not expressed in the pulmonary veins. CONCLUSIONS: The widespread distribution of HCN4 can explain the widespread location of the leading pacemaker site during sinus rhythm, the extensive region of tissue that has to be ablated to stop sinus rhythm, and the widespread distribution of ectopic foci responsible for atrial tachycardia.     

起搏通道基因亚型HCN4重组腺病毒载体的构建及通道电流检测

目的旨在构建超极化激活环核苷酸门控阳离子通道基因亚型4(HCN4)重组腺病毒载体并鉴定其离子通道功能。方法全长人HCN4基因酶切后亚克隆到腺病毒穿梭载体pAdTrack-CMV,形成含目的基因和绿色荧光蛋白基因的穿梭载体。穿梭载体和病毒骨架载体pAdEasy-1经电穿孔法在BJ5183大肠杆菌中同源重组,重组后的腺病毒载体经PacⅠ酶切线性化后,利用脂质体介导转染到HEK293细胞进行病毒的包装和扩增。用多聚酶链反应(PCR)方法对病毒上清中的HCN4进行检测,并将重组腺病毒感染COS-7细胞,用免疫荧光染色检测HCN4蛋白质的表达,利用全细胞膜片钳方法测定转HCN4基因细胞的电生理功能。结果通过酶切、测序、PCR等证实HCN4通道基因重组腺病毒载体构建正确,免疫荧光检测证实转染AdHCN4的COS-7细胞中HCN4通道基因的表达,膜片钳实验也在转基因细胞中检测到超极化激活的非选择性内向阳离子电流(If)。结论HCN4通道基因重组腺病毒载体的构建成功为进一步研究该离子通道的电生理功能及在心律失常疾病基因治疗方面的潜在应用价值奠定了基础。     

In situ co-distribution and functional interactions of SAP97 with sinoatrial isoforms of HCN channels

The sinoatrial node is a region of specialized cardiomyocytes that is responsible for the repetitive activity of the adult heart. The sinoatrial node is heavily innervated compared to the other regions of the heart, and the specialized cardiomyocytes of this region receive neural and hormonal input from the autonomic nervous system, which leads to changes in heart rate. A key regulator of sinoatrial beating frequency in response to autonomic input is the hyperpolarization-activated cyclic nucleotide gated (HCN) channel, a mixed cationic channel whose activity is increased by the binding of cAMP to its cytoplasmic side. HCN channels localize to distinct regions or “hot spots” on the cell surface of sinoatrial myocytes, but how these regions are formed, whether they correspond to specific signaling domains and the specific HCN isoforms and other proteins therein are not known. In this paper, we show that both HCN2 and HCN4 isoforms co-distribute with the adapter protein SAP97, an important component of distinct punctae in the sinoatrial node of the rabbit heart. HCN4, but not HCN2, also co-distributes with the post-synaptic marker β-catenin, thus identifying diverse organized domains within this tissue. Furthermore, we show, using heterologous expression systems, whole-cell patch clamp electrophysiology and imaging, that SAP97 interacts functionally with HCN in a manner that depends upon the PDZ compatible binding motif of the C-terminus, but that its effects on I_f behaviour are HCN isoform and context dependent. Together, the data suggest that SAP97 contributes to isoform specific organization of HCN channels within specific domains in the sinoatrial node of the rabbit.     

Tamoxifen-inducible gene deletion in the cardiac conduction system

Temporally controlled gene deletion provides a powerful technique for examination of gene function in vivo. To permit use of this technology in the study of cardiac pacemaking, we attempted to generate a mouse line expressing an inducible Cre recombinase selectively in cardiac pacemaker cells. The tamoxifen-inducible CreER^T2 construct was ‘knocked in’ into the pacemaker channel HCN4 locus. In the absence of inducing agent, recombination was undetectable in HCN4-KiT mice. After injection of tamoxifen, highly selective and efficient recombination was observed in the sinoatrial and atrioventricular node. Expression of Cre and tamoxifen per se did not affect cardiac rhythm, basal heart rate and heart rate modulation. By crossing these animals with floxed HCN4 mice, complete deletion of this gene in the sinoatrial node could be achieved. HCN4-KiT mice represent the first tool for the temporally controlled inactivation of floxed target genes selectively in the conduction system of the murine heart.     

重组起搏基因质粒构建生物起搏器的实验研究

目的研究旨在构建重组起搏基因质粒pIRES2-EGFP-HCN2,并检测其在体外心房肌细胞及犬病态窦房结综合征(病窦)模型体内的表达。方法对含mHCN2cDNA的PTR载体进行转化和扩增,将所得mHCN2基因定向克隆到真核表达载体pIRES2-EGFP中,进行双酶切来鉴定克隆的正确性。将重组质粒用电穿孔法转染心房肌细胞,同时直接注射至犬病窦模型的窦房结区域,体表心电图监测犬窦房结功能改善情况,并通过荧光显微镜及RT-PCR检测重组质粒pIRES2-EGFP-HCN2在体内外的表达。而对照组仅注射生理盐水。结果构建了重组质粒pIRES2-EGFP-HCN2。荧光显微镜下可见转染后的心房肌细胞呈绿色荧光,其搏动频率较未转染的细胞明显增快[(180±11)次/min与(140±14)次/min,P<0.05]。注射组织的冰冻切片显示绿色荧光蛋白,RT-PCR显示了mHCN2基因片段,体表心电图显示犬窦房结功能改善[(150±13)次/min与(105±17)次/min,P<0.05]。而对照组始终未见到绿色荧光蛋白表达及窦房结功能改善。结论成功构建了重组质粒pIRES2-EGFP-HCN2,并在体外心房肌细胞及犬病窦模型体内成功表达,为生物起搏的研究奠定基础。     

The heart rate-lowering agent ivabradine inhibits the pacemaker current I(f) in human atrial myocytes

Introduction: It has been speculated that pacemaker current (I _f ) in human atria could play a role in causing ectopic atrial automaticity. Ivabradine is a novel selective and specific I _f inhibitor in the sinus node that reduces heart rate without any negative inotropic effect. The aim of the study was to explore possible effects of ivabradine on I _f in atrial myocytes.
Methods and Results:  Using patch-clamp technique, we studied effects of ivabradine on I _f present in atrial myocytes isolated from human right appendages of patients undergoing cardiac surgery. The identification of HCN isoforms was obtained by means of multiplex single-cell RT-PCR. Ivabradine induced a marked concentration and use-dependent I _f inhibition with an IC₅₀ at steady state of 2.9 μM. Time constant of block development (Tau_on) decreases with the increase in the ivabradine concentration. Use-dependent inhibition induced by ivabradine (3 μM) was not modified in the presence of cAMP (10 μM) in the pipette solution. Multiplex single-cell RT-PCR indicates that the major HCN gene subtype detected in atria was HCN2. HCN4 is detected weakly and HCN1 is not significantly detected.
Conclusions:  Ivabradine inhibits I _f current in the nonpacemaker cell with characteristics similar to those described previously in rabbit sinus node cells, but revealed a lesser sensitivity for I _f recorded in human atrial cell than hHCN4 subunits considered as the major contributors to native f -channels in human sinoatrial node. A potential protection of atrial arrhythmias by ivabradine is discussed.