心肌远隔缺血预适应通过SDF-1α/CXCR4途径保护兔心肌缺血/再灌注损伤的研究

目的:探讨远隔缺血预适应对心肌缺血/再灌注(I/R)损伤保护作用及潜在机制。方法:成年雄性新西兰大白兔随机分成:(1)心肌缺血再灌注组(I/R组,n=6);(2)假手术组(Sham,n=6);(3)远隔缺血预适应(RIPC+I/R组,n=6);(4)SDF-1α/CXCR4阻断剂AMD3100+I/R组,(n=6);(5)AMD3100+RIPC+I/R组,(n=6)。ELISA检测外周血中SDF-1α;TTC检测心肌梗死面积;TUNEL检测细胞凋亡率;Western Blot检测Bcl-2、Bax蛋白表达。结果:与Sham组相比,I/R组及RIPC+I/R组都可促进外周血中SDF-1α的释放,且后者的作用更显著(P0.05);RIPC+I/R及AMD3100+RIPC+I/R组可以不同程度缩小心肌梗死面积及降低心肌细胞凋亡率(P0.05),AMD3100+RIPC+I/R组与RIPC+I/R组相比,心肌梗死面积及细胞凋亡率均有所增加(P0.05)。结论:远隔缺血预适应可能通过SDF-1α/CXCR4信号通路对心缺血再灌注损伤心肌发挥保护作用。     

乙酰半胱氨酸对糖尿病大鼠心肌缺血/再灌注后低氧诱导因子-1α和血红素加氧酶-1基因表达的影响

目的:观察乙酰半胱氨酸(NAC)对糖尿病大鼠心肌缺血/再灌注(I/R)后低氧诱导因子-1α(HIF-1α)和血红素加氧酶-1(HO-1)mRNA表达变化的影响.方法:用链脲佐菌素(STZ)复制糖尿病大鼠模型,动物分为正常假手术组(Cs组)、正常I/R组(CI/R组)、正常I/R+NAC组(CN组)、糖尿病假手术组(Ds组)、糖尿病I/R组(DI/R组)、糖尿病I/R+NAC组(DN组),每组12只,共72只.检测各组心肌梗死范围(IS/AAR)、HI-1α和HO-1 mRNA表达.结果:Cs组检测不到HIF-1α和HO-1 mRNA表达,Ds组检测到少量HIF-1α和HO-1 mRNA表达;DI/R组HIF-1α和HO-1 mRNA表达低于CI/R组(P＜0.05),IS/AAR大于CI/R组(P＜0.05);DN组HIF-1α和HO-1 mRNA表达高于DI/R组,但低于CN组(P＜0.05);IS/AAR小于DI/RR组,但大于CN组(P＜0.05).结论:NAC可部分恢复糖尿病大鼠心肌I/R后HIF-1α和HO-1 mRNA表达,减小心梗面积,有一定的治疗效果.     

二甲氧乙二酰甘氨酸对缺血性急性肾衰竭小鼠的保护作用

目的 观察二甲氧乙二酰甘氨酸(DMOG)对小鼠缺血性急性肾衰竭的影响及其与低氧诱导因子1α(HIF-1α)活化之间的关系.方法 雄性C57/BL小鼠25只,随机分为5组:正常对照组(Control组),DMOG组(20 mg/kg,ip),假手术组(Sham组)及肾缺血-再灌注组(I/R组)和DMOG预处理组(DMOG+I/R组).采用夹闭双侧肾蒂30 min的方法建立小鼠缺血性急性.肾衰竭模型,DMOG注射6 h或缺血-再灌注24 h后采血并处死小鼠,全自动生化分析仪检测小鼠的肾功能,通过HE染色对肾组织病理学进行评分,免疫组织化学染色检测肾组织中波形蛋白的表达,TUNEL法检测细胞凋亡,Western blot方法检测肾HIF-1α活化情况.结果 DMOG组小鼠肾组织中HIF-1α的表达明显高于正常对照组(P＜0.01);DMOG+I/R组小鼠.肾功能病理学评分明显低于I/R未处理组[BUN,(26.3±6.5) vs (65.8±2.6);Scr,(27.0±14.1) vs (229.5±11.2),P＜0.01],DMOG+I/R组细胞凋亡程度和小管波形蛋白的表达较I/R组明显减少[(5.7±1.5) vs (23.3±2.1),P＜0.05;(12.9±5.7) vs (69.6±22.7),P＜0.01].结论 DMOG可通过诱导HIF-1α活化对缺血性急性肾衰竭小鼠发挥保护作用.     

缺氧诱导因子-1对心肌细胞缺氧/复氧损伤的调节作用

目的 观察缺氧诱导因子-1α(hypoxia-inducible factor-1,HIF-1α)的活性与靶基因表达的变化,探讨其对体外培养的心肌细胞缺氧/复氧(hypoxia- reoxygenation,H/R)损伤的调节作用.方法 取SD新生大鼠(1～3日龄)分离培养心肌细胞;在培养的第3天将心肌细胞随机分为3组(每组重复6 次):正常对照组、缺氧/复氧组(H/R组)、甲基乙二酰基甘氨酸组(DMOG+H/R组);建立缺氧/复氧损伤模型,以脯氨酸羟化酶的抑制剂DMOG进行干预;观察各组心肌细胞的搏动频率;应用酶免疫法检测各组心肌细胞培养上清中的肌钙蛋白I(cTnI)含量;采用RT-PCR法检测各组HIF-1α及下游因子血红素氧合酶-1(HO-1)、血管内皮生长因子(VEGF)、葡萄糖转运蛋白-1(GLUT-1)mRNA水平.结果 与正常对照组相比,H/R组、DMOG+H/R组心肌细胞的搏动频率均明显减少(P﹤0.01),而DMOG+ H/R组心肌细胞的搏动频率又较H/R组明显升高(P﹤0.01);与正常对照组相比,H/R组、DMOG+H/R组的cTnI含量明显增高(P﹤0.01),且HIF-1α、HO-1、VEGF、GLUT-1 mRNA水平亦明显增高(P﹤0.01或P﹤0.05);与H/R组相比,DMOG+H/R组心肌细胞HIF-1α、HO-1、VEGF、GLUT-1 mRNA水平明显增高,而cTnI含量则明显降低(P﹤0.05).结论 HIF-1的稳定表达对心肌细胞缺氧/复氧损伤具有保护作用.     

TLR4/NF-κB参与缺血后处理大鼠脊髓保护作用机制研究

目的探讨Toll样受体4(TLR4)/核因子κB(NF-κB)信号通路在缺血后处理介导大鼠脊髓缺血再灌注损伤保护中作用,为缺血后处理用于脊髓保护提供新的理论支持。方法成年雄性SD大鼠80只随机分为5组(每组16只):假手术组(Sham组)、缺血再灌注组(I/R组)、缺血后处理组(Post C组)、TLR4拮抗剂TAK-242+I/R组(I/R+T组)、后处理+TAK-232组(Post C+T组)。Sham组分离血管但不阻断;I/R组分离腹主动脉夹闭20 min后开放;Post C组缺血20 min后,于再灌注即刻行再灌注30 s/缺血30 s处理,重复3次,然后行完全再灌注;I/R+T组缺血前尾静脉注射TAK-232(10 mg/kg),余同I/R组;Post C+T组缺血前尾静脉注射TAK-232,余同Post C组。各组动物在再灌注24 h、48 h行神经行为学评分;再灌注48 h取L4-6段脊髓,采用免疫荧光染色及Western blot技术检测脊髓组织中TLR4及NF-κB表达。结果与I/R组相比,其余各组再灌注24 h、48 h神经行为学评分均改善(P0.05);而给予TLR4拮抗剂TAK-242可逆转后处理的神经保护作用,即与Post C组相比,再灌注24 h、48 h Post C+T组神经行为学评分均增加(P0.05)。与I/R组相比,其余各组再灌注48 h脊髓组织中TLR4表达均显著减少(P0.05);与Post C组相比,Post C+T组TLR4表达显著减少(P0.05)。与I/R组相比,其余各组再灌注48 h脊髓组织中NF-κB表达均显著减少(P0.05);与Post C组相比,Post C+T组NF-κB表达则显著增加(P0.05)。结论 TLR4/NF-κB信号通路参与缺血后处理介导大鼠脊髓的保护作用。     

过氧化物酶体增殖物激活型受体γ对原位肝移植胆道缺血-再灌注损伤的作用

目的 探讨过氧化物酶体增殖物激活型受体γ(peroxisome proliferators activated receptor-gamma,PPAR-γ)及配体罗格列酮(rosiglitazone,Ros)对原位肝移植胆道缺血-再灌注损伤(Ischemia/reper-fusion,I/R)的影响及其作用机制.方法 42只SD大鼠随机分为假手术组(n=14),I/R组(n=14)和I/R+Ros组(n=14).通过制作人鼠肝脏原位缺血-再灌注模型,采用信号通路发现者基因芯片和大鼠细胞冈予抗体芯片检测技术,榆测胆道组织炎症反应发生的信号通路和相关的细胞因子的变化;并采用肝脏组织病理学评分和部分器官功能生化指标的检测,以观察大鼠缺血-再灌注损伤时肝脏组织的病理变化和部分器官牛化指标的变化.采用SPSS 10.0软件进行统计学分析.实验中测得的数据以均数±标准差(x±s)表示.应用方差分析和Bonferroni检验,P＜0.05为差异具有统计学意义.结果 I/R组中NF-кB样本基因表达水平均比假于术组和I/R+Ros组丌高两倍以上.使用大鼠细胞因子抗体芯片发现,I/R组中IL-Iα,IL-β以及TNF-α样本蛋白表达水平均比假手术组和I/R+Ros组升高两倍以上.与I/R组相比,I/R+Ros组巾病理学评分明显下降(P＜0.05);部分器官生化指标含量测定明显下降(P＜0.01).结论 PPAR-γ及配体罗格列嗣对原位肝移植胆道缺血-再灌注损伤有保护作用,其机制与通过拮抗核因子-кB(NF-кB),抑制NF-кB表达,减少下游IL-Iα,IL-1β以及TNFα等炎性介质的释放有关.     

蛇床子素后处理对大鼠心肌急性缺血/再灌注损伤心肌细胞凋亡的影响及其可能机制

目的观察蛇床子素后处理对大鼠心肌急性缺血/再灌注损伤心肌细胞凋亡的影响,并对其可能的作用机制进行探讨。方法结扎大鼠左冠状动脉前降支30 min后,松开结扎线再灌注120 min制备急性心肌缺血/再灌注损伤模型;将30只Wistar大鼠随机分为以下3组:对照(Sham)组、缺血/再灌注(I/R)组、I/R+蛇床子素后处理(Ost)组。采用TUNEL法原位标记缺血区凋亡心肌细胞并计算凋亡指数,采用Western blot法检测心肌组织中Caspase-3、Bcl-2及Bax三种蛋白的表达。结果与Sham组相比,I/R组心肌细胞凋亡指数、心肌组织Caspase-3蛋白、Bcl-2蛋白和Bax蛋白含量明显增高(均P<0.05);与I/R组相比,Ost组心肌细胞凋亡指数(P<0.05)、心肌组织Caspase-3蛋白(P<0.01)及Bax蛋白表达水平均降低(P<0.05),而Bcl-2蛋白表达水平明显增高(P<0.05)。结论蛇床子素后处理能抑制急性心肌缺血/再灌注损伤所致的大鼠心肌细胞凋亡,同时上调心肌组织中Bcl-2蛋白的表达及下调心肌组织中Bax蛋白的表达,提示上调Bcl-2蛋白及下调Bax蛋白、进而上调Bcl-2/Bax比值可能是其发挥抗心肌细胞凋亡作用的机制。     

家兔短暂心肌缺血后VEGF蛋白表达的空间规律

目的:研究短暂心肌缺血后血管内皮生长因子(VEGF)的空间表达规律。方法:建立新西兰兔心肌缺血模型。根据再灌注时间分为3h、4h、6h、7h以及假手术组(n=6)。Westernblotting检测VEGF在缺血区心肌、非缺血区心肌、肾、骨骼肌、血浆、肝、肺以及脑组织的表达。结果:与假手术组相比,心肌、肾、骨骼肌、血液、肝和肺的VEGF表达升高(P<0.05)。血液的VEGF和缺血区心肌中VEGF相关(P<0.05)。结论:心肌缺血刺激使心肌VEGF表达增高,也使邻近组织和远隔组织的表达增加;血液与心肌VEGF具有相关性。     

栀子苷预处理对大鼠心肌缺血再灌注后PI3K/Akt信号通路的研究

目的探索栀子苷(GEN)对大鼠心肌缺血再灌注(I/R)后心肌细胞氧化应激水平及心肌凋亡的影响极其与PI3K/Akt信号通路的关系。方法60只SD大鼠随机分为3组:缺血再灌注组(I/R),栀子苷预处理+缺血再灌注组(GEN+I/R),栀子苷+缺血再灌注组+PI3K/Akt信号通路抑制剂(LY294002)组(GEN+I/R+LY),GEN+I/R组在I/R造模前给予50 mg/kg GEN预处理,GEN+I/R+LY组在GEN预处理前给予0.3 mg/kg LY294002。ELISA法检测大鼠血清乳酸脱氢酶(LDH)、心肌组织丙二醛(MDA)和超氧化物歧化酶(SOD)以及钙泵(Ca~(2+)-ATPase)水平;Western blot检测心肌组织p-e NOS,p-Akt,Akt以及Bcl-2、Bax蛋白表达;免疫组织化学染色检测p-e NOS,p-Akt蛋白表达。结果与I/R组比较,GEN+I/R组LDH、MDA含量显著降低,SOD、Ca~(2+)-ATPase显著升高(P0.05);与GEN+I/R组比较,GEN+I/R+LY组LDH、MDA含量显著升高,SOD、Ca~(2+)-ATPase显著降低(P0.05)。并且,与I/R组比较,GEN+I/R组p-eNOS、p-Akt、Akt、Bcl-2表达量以及p-e NOS,p-Akt免疫荧光强度显著提高(P0.05),Bax蛋白表达显著降低(P0.05);与GEN+I/R组比较,GEN+I/R+LY组p-eNOS、p-Akt、Akt、Bcl-2表达量以及pe NOS、p-Akt免疫荧光强度显著降低,Bax蛋白表达量显著升高(P0.05)。结论栀子苷可通过激活PI3K/Akt信号通路抑制心肌缺血再灌注后氧化应激及细胞凋亡从而发挥保护作用。     

七氟醚预处理早期对大鼠心肌缺血再灌注心肌细胞自噬的影响

目的探讨七氟醚预处理早期对大鼠心肌缺血再灌注心肌保护作用及对心肌细胞自噬的影响。方法清洁级雄性SD大鼠45只,8~12周龄,体质量200~240 g。随机分为假手术组(Sham组,n=15)、缺血再灌注组(I/R组,n=15)和七氟醚预处理组(Sevo组,n=15)。采用冠脉阻断30 min再灌注120 min的方法制备大鼠心肌缺血再灌注损伤模型。Sevo组于缺血前30 min行七氟醚预处理:吸入2.5%七氟醚15 min,洗脱15 min。随后结扎左前降支,阻断冠脉血流30 min后,解除阻断再灌注120 min。再灌注120 min时测定肌钙蛋白I(c Tn I)和肌酸激酶同工酶(CK-MB)的浓度、心肌梗死面积、LC3-Ⅱ和Beclin-1的蛋白表达情况。结果与Sham组比较,I/R组心肌c Tn I和CK-MB浓度升高,心肌梗死面积增加,LC3-Ⅱ和Beclin-1蛋白表达上调(P0.05);与I/R组比较,Sevo组心肌c Tn I和CK-MB浓度降低,心肌梗死面积减少(P0.05),LC3-Ⅱ和Beclin-1蛋白表达差异无统计学意义(P0.05)。结论七氟醚预处理早期能减轻心肌缺血再灌注损伤,但是七氟醚预处理早期未显著影响心肌细胞自噬水平。     

Standardization of assays of factor VIII and factor IX

Summary The development of international standards over the last 15–20 years has led to improved interlaboratory agreement on assays of factor VIII and factor IX. In the most recent international collaborative study, the coefficient of variation for one-stage assays (26 laboratories) was 5.6%. However, in quality assurance surveys, carried out in the UK and USA, agreement between laboratories is much less good, with coefficients of variation ranging from 30% to over 50%. Improvements in agreement between clinical laboratories could be obtained by increasing the amount of testing on each sample, especially the number of dilutions, and reducing the number of reagent systems used. A large number of laboratories now use immunodepleted plasmas instead of congenitally deficient plasmas as substrates for one-stage assays. These plasmas may give satisfactory assays, but many of them have not been thoroughly evaluated in comparison with congenitally deficient plasma. In assessment of potency of very high purity (VHP) factor VIII concentrates, some immunodepleted plasmas were found to give lower potencies than hemophilic plasma. This is partly due to the fact that VHP concentrates contain little or no von Willebrand factor (vWF), and most immunodepleted plasmas are also deficient in vWF. In recent collaborative studies, assays of VHP factor VIII concentrate were much more variable, both within and between laboratories, than assays of intermediate purity concentrates. Standardization of these new products will require careful attention to methodological detail. Presented at the ‘2nd International Symposium on Standardization and Quality Control of Coagulation Tests: Implications for the Clinical Laboratory’, Rome, September 28–29, 1989.     

Inhibition of the activation of Hageman factor (factor XII) by platelet factor 4

Platelet factor 4 is a polypeptide constituent of platelet alpha granules that is released during platelet aggregation and inhibits heparin-mediated reactions. Hageman factor (factor XII) is a plasma proenzyme that, when activated by certain negatively charged agents, initiates clotting via the intrinsic pathway of thrombin formation. In earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by dextran sulfate or cerebrosides, but not activation of Hageman factor by kaolin or ellagic acid. In the present study we examined the mechanisms of inhibition by platelet factor 4, using purified reagents. Platelet factor 4 inhibited activation of Hageman factor by ellagic acid, as measured by amidolysis of a synthetic substrate of activated Hageman factor, an effect inhibited by heparin or by an anti-platelet factor 4 antiserum. Coating glass tubes with platelet factor 4 before addition of normal plasma significantly lengthened the partial thromboplastin time of normal plasma. In addition, the clot-promoting properties of kaolin were inhibited by its prior exposure to platelet factor 4. Thus, the inhibitory properties of platelet factor 4 directed against the activation of Hageman factor were confirmed in a purified system. In this purified system, in contrast to earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by glass, ellagic acid, or kaolin.     

A transforming growth factor beta-like immunosuppressive factor in immunoglobulin G-binding factor

Immunoglobulin G-binding factors (IgG-BF), which are produced by cells of the immune system, inhibit antibody production. In this paper, we show that transforming growth factor-beta (TGF-beta) suppresses secondary in vitro anti-sheep red blood cell responses of mouse splenocytes and lipopolysaccharide- or anti-IgM-stimulated mouse B cell responses in a way similar to, and with the same kinetics as, rodent IgG-BF. Moreover, the immunosuppressive activity of IgG-BF was totally neutralized by polyclonal and monoclonal anti-TGF-beta antibodies and it eluted with TGF-beta by gel exclusion chromatography, suggesting that a TGF-beta-like immunosuppressive factor is present in IgG-BF. We also show that TGF-beta behaves as an IgG-BF since it binds to insolubilized IgG, but not to insolubilized F(ab')2 or bovine serum albumin. Altogether, the data support the concept of a biological role for TGF-beta in the IgG-mediated negative feedback of antibody responses.     

The association of factor VIII with von Willebrand factor

Factor VIII (FVIII) and von Willebrand factor (vWF) are plasma glycoproteins that circulate as a tightly associated complex. Because they tend to copurify during procedures designed to isolate the biologic activities associated with them, their identity as distinct entities became unequivocally established only during the past 10 years. Improved procedures for the isolation of FVIII, the deduction of the amino acid sequences of FVIII and vWF by using molecular cloning techniques and by direct sequencing, and the use of a variety of biophysical and immunochemical techniques have enhanced the understanding of the FVIII-vWF association. Each subunit of multimeric vWF potentially can bind a single heterodimeric FVIII molecule, although in vivo most of these binding sites are empty. The binding of FVIII to vWF is primarily, if not exclusively, mediated by the light chain of FVIII to the amino-terminal region of the vWF subunit. Cleavage of a fragment from the amino-terminal region of the FVIII light chain by thrombin results in rapid dissociation of the FVIII-vWF complex, a process that apparently is necessary for development of procoagulant activity. Whether this cleavage is needed for the activation of FVIII in the absence of vWF is controversial. The extracellular association of FVIII with vWF may be necessary for efficient secretion of FVIII from its cell of origin. The thermodynamics, kinetics, and nature of the molecular contacts involved in the interaction have not been studied. The association of FVIII with vWF prolongs the lifetime of FVIII in plasma. Whether the FVIII-vWF interaction has other functional roles, such as restricting the location of procoagulant activity, remains unknown.     

Activation of human factor IX (Christmas factor).

Human Factor IX (Christmas factor) is a single-chain plasma glycoprotein (mol wt 57,000) that participates in the middle phase of the intrinsic pathway of blood coagulation. It is present in plasma as a zymogen and is converted to a serine protease, Factor IXabeta, by Factor XIa (activated plasma thromboplastin antecedent) in the presence of calcium ions. In the activation reaction, two internal peptide bonds are hydrolyzed in Factor IX. These cleavages occur at a specific arginyl-alanine peptide bond and a specific arginyl-valine peptide bond. This results in the release of an activation peptide (mol wt approximately equal to 11,000) from the internal region of the precursor molecule and the generation of Factor IXabeta (mol wt approximately equal to 46,000). Factor IXabeta is composed of a light chain (mol wt approximately equal to 18,000) and a heavy chain (mol wt approximately equal to 28,000), and these chains are held together by a disulfide bond(s). The light chain originates from the amino terminal portion of the precursor molecule and has an amino terminal sequence of Tyr-Asn-Ser-Gly-Lys. The heavy chain originates from the carboxyl terminal region of the precursor molecule and contains an amino terminal sequence of Val-Val-Gly-Gly-Glu. The heavy chain of Factor IXabeta also contains the active site sequence of Phe-Cys-Ala-Gly-Phe-His-Glu-Gly-Arg-Asp-Ser-Cys-Gln-Gly-Asp-SER-Gly-Gly-Pro. The active site serine residue is shown in capital letters. Factor IX is also converted to Factor IXaalpha by a protease from Russell's viper venom. This activation reaction, however, occurs in a single step and involves only the cleavage of the internal arginyl-valine peptide bond. Human Factor IXabeta was inhibited by human antithrombin III by the formation of a one-to-one complex of enzyme and inhibitor. In this reaction, the inhibitor was tightly bound to the heavy chain of the enzyme. These data indicate that the mechanism of activation of human Factor IX and its inhibition by antithrombin III is essentially identical to that previously shown for bovine Factor IX.     

Radioimmunoassay of antihaemophilic factor (factor VIII) antigen

A simple, precise radioimmunoassay for antihaemophilic factor (AHF, factor VIII) antigen has been developed. The technique is based upon a double-antibody solid-phase (DASP) system. This assay may serve as a specific method for differentiation between Von Willebrand's disease and haemophilia A.