抗细胞趋化因子CCL21单克隆抗体处理对小鼠急性心肌梗死后左心室重构及心功能的影响

目的：探讨抗CCL21单克隆抗体处理对小鼠急性心肌梗死后心室重构和心功能的影响。方法：C57BL/6小鼠随机分为假手术组、模型组和CCL21单抗干预组,并进一步分为1、3、7和21 d亚组。采用结扎冠状动脉左前降支的方法构建小鼠急性心肌梗死模型,在冠状动脉结扎后5 min和第3天,模型组小鼠静脉注射isotype-IgG 1.0 mg,CCL21单抗干预组小鼠静脉注射山羊抗小鼠CCL21单克隆抗体1.0 mg。建模后,Western blot法检测急性心肌梗死后第1、3、7天心肌组织CCR7表达,检测急性心肌梗死后第7天心肌组织MMP-2和MMP-9表达;建模后第1、3、7天,ELISA法检测各组小鼠血清TNF-α和IL-6水平,每组检测8只小鼠。在建模后第7天和21天,超声心动图法评估左心室功能变化。结果：与假手术组比较,模型组小鼠急性心肌梗死后血清CCL21、TNF-α和IL-6及心肌组织CCR7、MMP-2、MMP-9明显升高（P<0.05）;与模型组比较,CCL21单抗干预组小鼠血清TNF-α和IL-6及梗死区心肌组织MMP-9水平明显降低（P<0.05）。结论：抗CCL21单克隆抗体处理,通过抑制梗死后炎症反应及MMP-9表达水平发挥防止小鼠心脏重构和保护左心室功能的效应。     

改良气管插管法在小鼠心肌梗死模型制备中的应用

目的：小鼠心肌梗死模型制备中采用改良气管插管方法,提高模型制备成功率。方法：小切口暴露小鼠气管,直视下进行经口气管插管,左冠状动脉前降支结扎制备心肌梗死模型,观察、记录小鼠心脏颜色和心电图、术后14d存活情况和心肌组织病理学变化。结果：采用改良气管插管,成功完成40只小鼠心肌梗死模型制作,均可见冠状动脉结扎后,心室前壁颜色变暗,心电图Ⅱ导联ST段明显抬高。除去手术过程中意外死亡,术后14d存活27只,心肌梗死小鼠实际成活率达到87．1％。开胸后,肉眼可见模型组小鼠左室心腔明显扩大,心室壁变薄;病理切片HE染色,镜下可见心肌纤维断裂溶解,心肌细胞坏死,大量炎性细胞浸润。结论：在小鼠心肌梗死模型制备中,采用改良气管插管法,操作简单、易行、创伤小,模型制备成功率高。     

酸吸入性肺损伤小鼠模型的建立

目的建立一种无创伤、可进行纵向研究的酸吸入导致肺损伤的小鼠模型。方法麻醉后的C57BL/6小鼠利用光纤光源引导进行口腔气管插管,配合侧卧体位及施压小鼠左肺,向其右侧肺部分别导入2.5μL/g、0.1 mol/L、p H 1.5的盐酸或对照生理盐水。手术完成后对小鼠进行供氧4 h恢复。手术后对小鼠的存活率及肺功能生理指标进行监测,确定肺损伤后小鼠病程发展各项检测指标。结果经上述方法建立的无创伤酸吸入小鼠,染色显示液流成功导入小鼠右侧肺部,存活率(80%)显著高于气管切口插管的小鼠。肺功能检测(湿干重比、回弹性、动脉血氧饱和度)和组织学切片表明,盐酸的导入引起小鼠肺部严重病理反应和功能障碍。对小鼠肺盥洗液分析揭示酸吸入导致大量嗜中性粒细胞进入肺泡,并可在肺泡中检测到高含量免疫炎性因子TNF-α、IL-6、CXCL1和CXCL2。结论采用可视化无创伤的口腔气管插管技术,同时灌注盐酸所建立的酸吸入肺损伤小鼠模型,为进一步研究肺部免疫炎症机理提供了平台。     

兔在体心脏缺血再灌注模型的制作方法的改进

目的建立兔在体心脏缺血再灌注模型的新方法。方法40只新西兰大白兔随机分为缺血再灌注组（25只）,假手术组（15只）。缺血再灌注组采用＂二线二结＂法结扎心脏左前降支30 min,然后恢复心肌灌注3h;假手术组仅将线从左前降支周围心肌中穿过,但并不结扎。实验中连续描记心电图。两组分别于结扎（穿线）前和再灌注（穿线）后1 h从股静脉取血1 mL测定血清肌钙蛋白。实验结束时取心肌行2,3,5-氯化三苯基四氮唑和苏木精-伊红染色。结果缺血再灌注组心电图存在ST-T的动态演变,再灌注1 h后血清肌钙蛋白浓度明显高于术前（0.47±0.35 vs.0.33±0.31,P=0.002）。两种染色方法均证明存在心肌坏死。结论＂二线二结＂法能够既方便又成功地建立兔在体心脏缺血再灌注模型。     

大鼠心肌梗死模型建立方法选择及心电图表现

目的探讨构建心肌梗死模型的大鼠左冠状动脉结扎位置及心电图特点。方法 SD大鼠经麻醉后,气管切开插管及连通呼吸机,打开左侧胸腔后分别在距离左心耳尖端约2 mm水平处(低位结扎组)与在距主动脉根部约3 mm处(高位结扎组)结扎左冠动脉,假手术组除不结扎冠脉外步骤同低位结扎组,术前术后分别行心电图检查,且4周后取出心脏行病理学检查及测定心肌梗死面积。结果高位结扎组大鼠心肌梗死面积约55.5%,总存活率13.3%;低位结扎组大鼠心肌梗死面积约36.2%,总存活率66.7%;假手术组大鼠无心肌梗死,存活率100%。大鼠体表心电图在非心肌梗死者QRS-T波群呈成"M"型波,在心肌梗死者R波与T波融合成高大的帐篷状单波,无明显ST段。4周后心肌组织形态学特点符合心肌梗死的病理改变。结论距大鼠主动脉根部约3 mm结扎左冠状动脉,不能满足实验需要;距离左心耳尖端约2 mm水平结扎左冠状动脉,能满足实验需要;大鼠的体表心电图无明显ST段。     

冠脉结扎和介入两种方法制备犬心肌梗死模型的比较

目的观察开胸结扎冠状动脉与闭胸明胶海绵栓塞法制备急性心肌梗死（AMI）动物模型的特点。方法分别经开胸结扎犬冠状动脉左前降支主干及闭胸冠脉栓塞的方法阻断冠脉血流;采用单级肢体导联和胸导联方式,在阻断前后监测心电图波形变化;造模72h后取心肌组织行病理切片染色。结果经心电图和病理验证,两种方法均可成功制备犬心梗模型,开胸冠脉结扎犬死亡率较高,而冠脉栓塞成活率高。结论相较开胸冠脉结扎法,闭胸栓塞法制备心梗模型对动物损伤小,成活率高,具推广价值。     

胚胎干细胞对孕鼠缺血受损心肌的修复作用

目的探讨胎鼠胚胎干细胞是否可通过血液循环系统进入怀孕母体,并对孕鼠缺血损伤的心肌组织进行修复。方法将24只6~8周龄C57雌性小鼠随机分为假手术组(n=8)、手术+受孕组(n=8)和手术组+未受孕组(n=8),通过结扎冠状动脉左前降支的方法制作心肌梗死模型,并将手术后受孕组小鼠与e-GFP转基因雄鼠进行杂交。三组小鼠分别在术前、术后和孕产后进行心电图和超声心动检测,比较其心功能的变化;通过免疫组织化学染色,观察各组小鼠心肌结构的变化,并检测孕鼠心肌是否表达荧光蛋白,以确定是否存在胚胎来源的Gfp阳性细胞。同时通过普通半定量PCR扩增技术检测孕鼠血液DNA中是否存在Gfp基因。结果手术+受孕组及手术+未受孕组小鼠术后心电图结果可见其ST段具有显著抬高,提示出现明显的心肌缺血表现,而手术+受孕组小鼠产后心电图结果提示其缺血症状较孕前减轻。超声结果也证实手术后小鼠均出现明显的心肌梗死表现,手术+受孕组小鼠产后心腔结构虽较孕前未见明显改变,各项心功能指标较假手术组减低,但与手术+未受孕组相比,心功能指标明显升高(P0.05)。此外,通过免疫组化染色和PCR检测发现手术+受孕组心肌梗死区域具有GFP阳性表达,而其他两组均为GFP阴性。结论胎鼠的胚胎干细胞可透过胎盘屏障,随血液迁移至母孕鼠体内,并对缺血损伤的心肌进行修复。     

心肌特异性Creg基因条件敲除小鼠的建立及表型分析

目的:建立心肌特异性Creg基因敲除小鼠并初步分析其表型。方法:利用订购的Creg两端插入lox P位点(Cregflox/flox)的小鼠与肌型肌酸激酶特异性启动子驱动的Cre重组酶转基因(Ckmm-cre)小鼠交配,获得Cregflox/+/Ckmm-cre小鼠。再利用Cregflox/+/Ckmm-cre小鼠互相交配,获得基因型为Cregflox/flox/Ckmm-cre的心肌特异性Creg基因条件敲除(Creg conditional knockout,Creg c KO)小鼠。用PCR法进行基因型鉴定。用定量PCR及Western Blot检测心肌组织中Creg表达水平。HE染色观察敲除小鼠与同窝野生型对照小鼠心脏大小及形态。检测两组小鼠心电图。用小动物超声评价两组小鼠左心室收缩功能。结果:1经基因型鉴定,成功获得Creg c KO小鼠。2与野生型对照相比,Creg c KO小鼠心脏中CREG在转录及翻译水平表达降低90%以上。3与野生型对照相比,Cre c KO小鼠的心脏大小、形态、心电图及左心室射血分数均无显著差别。结论:成功建立心肌特异性CREG基因条件敲除小鼠,为进一步研究Creg在心脏疾病中的作用和机制提供了有力的工具。     

小白鼠升主动脉缩窄术

目的 :探讨小鼠心肌肥厚模型中手术的关键性技术问题。方法 :小鼠麻醉后右侧第三肋间开胸 ,用自制过线器在升主动脉下穿线 ,连同主动脉一起结扎在 2 6g针头上 ,退出针头 ,使升主动脉周长缩小约 1/ 3。 结果 :术后 5周 ,小鼠成活率为 70 % ,左心室 /体重明显大于对照组 ,动物不出现心包炎。结论 :此方法简便有效 ,重复性好 ,得到的模型便于研究离体肥厚心脏的功能和分离心肌细胞。     

缩醛基毛冬青提取化合物R4对缺血缺氧心肌的保护作用

目的：研究缩醛基毛冬青提取化合物R4对缺血缺氧心肌的保护作用,以便为缩醛基毛冬青提取化合物R4的临床新用途提供实验依据。方法：采用小鼠常压耐缺氧实验、夹闭气管小鼠心电消失时间、垂体后叶素所致大鼠心肌缺血模型及大鼠冠脉结扎所致的心肌缺血模型,观察缩醛基毛冬青提取化合物R4对缺血缺氧心肌的保护作用。结果：缩醛基毛冬青提取化合物R4（1.0、2.0、4.0 mg/kg）均能显著延长小鼠常压耐缺氧条件下的存活时间,延长夹闭气管小鼠心电消失时间,缩醛基毛冬青提取化合物R4（0.75、1.5和3.0 mg/kg）能拮抗垂体后叶素引起的心电图变化,并能明显降低结扎冠脉所致大鼠的心肌梗塞范围。结论：缩醛基毛冬青提取化合物R4对缺血缺氧心肌具有明显保护作用,其效应与剂量呈相关性,其机制可能是通过扩张冠脉,增加心肌的供血供氧而发挥抗心肌缺血的作用。     

A general class of Bayesian survival models with zero and nonzero cure fractions

We propose a new class of survival models which naturally links a family of proper and improper population survival functions. The models resulting in improper survival functions are often referred to as cure rate models. This class of regression models is formulated through the Box-Cox transformation on the population hazard function and a proper density function. By adding an extra transformation parameter into the cure rate model, we are able to generate models with a zero cure rate, thus leading to a proper population survival function. A graphical illustration of the behavior and the influence of the transformation parameter on the regression model is provided. We consider a Bayesian approach which is motivated by the complexity of the model. Prior specification needs to accommodate parameter constraints due to the non-negativity of the survival function. Moreover, the likelihood function involves a complicated integral on the survival function, which may not have an analytical closed form, and thus makes the implementation of Gibbs sampling more difficult. We propose an efficient Markov chain Monte Carlo computational scheme based on Gaussian quadrature. The proposed method is illustrated with an example involving a melanoma clinical trial.     

Cis requirements for alternative splicing of the cardiac troponin T pre-mRNA.

The cardiac troponin T (cTNT) pre-mRNA splices 17 exons contiguously but alternatively splices (includes or excludes) the fifth exon. Because both alternative splice products are processed from the same pre-mRNA species, the cTNT pre-mRNA must contain cis-acting sequences which specify exon 5 as an alternative exon. A cTNT minigene (SM-1) transfected into cultured cells produces mRNAs both including and excluding exon 5. The junctions of exons 4-5-6 and 4-6 in the cTNT minigene mRNAs are identical to those of endogenous cTNT mRNAs and no other exons are alternatively spliced. Thus, the SM-1 pre-mRNA is correctly alternatively spliced in transfected cells. To circumscribe the pre-mRNA regions which are required for the alternative nature of exon 5, we have constructed a systematic series of deletion mutants of SM-1. Transfection of this series demonstrates that a 1200 nt pre-mRNA region containing exons 4, 5, and 6 is sufficient to direct alternative splicing of exon 5. Within this region are two relatively large inverted repeats which potentially sequester the alternative exon via intramolecular base-pairing. Such sequestration of an alternative exon is consistent with models which propose pre-mRNA conformation as being determinative for alternative splicing of some pre-mRNAs. However, deletion mutants which remove the majority of each of the inverted repeats retain the ability to alternatively splice exon 5 demonstrating that neither is required for cTNT alternative splice site selection. Taken together, deletion analysis has limited cis elements required for alternative splicing to three small regions of the pre-mRNA containing exons 4, 5, and 6. In addition, the cTNT minigene pre-mRNA expresses both alternative splice products in a wide variety of cultured non-muscle cells as well as in cultured striated muscle cells, although expression of the cTNT pre-mRNA is normally restricted to striated muscle. This indicates that cis elements involved in defining the cTNT exon 5 as an alternative exon do not require muscle-specific factors in trans to function.     

Semiparametric regression in capture-recapture modeling

Capture-recapture models were developed to estimate survival using data arising from marking and monitoring wild animals over time. Variation in survival may be explained by incorporating relevant covariates. We propose nonparametric and semiparametric regression methods for estimating survival in capture-recapture models. A fully Bayesian approach using Markov chain Monte Carlo simulations was employed to estimate the model parameters. The work is illustrated by a study of Snow petrels, in which survival probabilities are expressed as nonlinear functions of a climate covariate, using data from a 40-year study on marked individuals, nesting at Petrels Island, Terre Adélie.     

The CELF family of RNA binding proteins is implicated in cell-specific and developmentally regulated alternative splicing

Alternative splicing of cardiac troponin T (cTNT) exon 5 undergoes a developmentally regulated switch such that exon inclusion predominates in embryonic, but not adult, striated muscle. We previously described four muscle-specific splicing enhancers (MSEs) within introns flanking exon 5 in chicken cTNT that are both necessary and sufficient for exon inclusion in embryonic muscle. We also demonstrated that CUG-binding protein (CUG-BP) binds a conserved CUG motif within a human cTNT MSE and positively regulates MSE-dependent exon inclusion. Here we report that CUG-BP is one of a novel family of developmentally regulated RNA binding proteins that includes embryonically lethal abnormal vision-type RNA binding protein 3 (ETR-3). This family, which we call CELF proteins for CUG-BP- and ETR-3-like factors, specifically bound MSE-containing RNAs in vitro and activated MSE-dependent exon inclusion of cTNT minigenes in vivo. The expression of two CELF proteins is highly restricted to brain. CUG-BP, ETR-3, and CELF4 are more broadly expressed, and expression is developmentally regulated in striated muscle and brain. Changes in the level of expression and isoforms of ETR-3 in two different developmental systems correlated with regulated changes in cTNT splicing. A switch from cTNT exon skipping to inclusion tightly correlated with induction of ETR-3 protein expression during differentiation of C2C12 myoblasts. During heart development, the switch in cTNT splicing correlated with a transition in ETR-3 protein isoforms. We propose that ETR-3 is a major regulator of cTNT alternative splicing and that the CELF family plays an important regulatory role in cell-specific alternative splicing during normal development and disease.     

The cardiac troponin T alternative exon contains a novel purine-rich positive splicing element.

We have characterized a novel positive-acting splicing element within the developmentally regulated alternative exon (exon 5) of the cardiac troponin T (cTNT) gene. The exon splicing element (ESE) is internal to the exon portions of the splice sites and is required for splicing to the 3' splice site but not the 5' splice site flanking the exon. Sequence comparisons between cTNT exon 5 and other exons that contain regions required for splicing reveal a common purine-rich motif. Sequence within cTNT exon 5 or a synthetic purine-rich motif facilitates splicing of heterologous alternative and constitutive splice sites in vivo. Interestingly, the ESE is not required for the preferential inclusion of cTNT exon 5 observed in primary skeletal muscle cultures. Our results strongly suggest that the purine-rich ESE serves as a general splicing element that is recognized by the constitutive splicing machinery.     

Muscleblind proteins regulate alternative splicing

Although the muscleblind (MBNL) protein family has been implicated in myotonic dystrophy (DM), a specific function for these proteins has not been reported. A key feature of the RNA-mediated pathogenesis model for DM is the disrupted splicing of specific pre-mRNA targets. Here we demonstrate that MBNL proteins regulate alternative splicing of two pre-mRNAs that are misregulated in DM, cardiac troponin T (cTNT) and insulin receptor (IR). Alternative cTNT and IR exons are also regulated by CELF proteins, which were previously implicated in DM pathogenesis. MBNL proteins promote opposite splicing patterns for cTNT and IR alternative exons, both of which are antagonized by CELF proteins. CELF- and MBNL-binding sites are distinct and regulation by MBNL does not require the CELF-binding site. The results are consistent with a mechanism for DM pathogenesis in which expanded repeats cause a loss of MBNL and/or gain of CELF activities, leading to misregulation of alternative splicing of specific pre-mRNA targets.