Coagulopathy after snake bite byBothrops neuwiedi: Case report and results of in vitro experiments

Summary Coagulation studies were performed in a patient who had been bitten by a snake of the speciesBothrops neuwiedi. The patient presented with hemorrhagic necrosis at the envenomization site and considerable bleeding from venous puncture sites. He developed a severe defibrination syndrome with a clottable fibrinogen level of approximately 0.1 g/l. Fibrinogen was not measurable by clotting time assay. Fibrin degradation products were greatly elevated. Treatment with antivenom caused an anaphylactic reaction within ten minutes and serum sickness after three days. In vitro experiments revealed thatB. neuwiedi venom directly activates Factors II and X, but does not activate Factor XIII. In vivo consumption of Factor XIII afterB. neuwiedi envenomization is ascribed to the action of Factor IIa. At low venom concentrations clotting is initiated by activation of prothrombin by the venom either directly or via Factor X activation. Treatment with heparin might be beneficial in coagulopathy secondary to snake bite by reducing circulating active thrombin. The venom contains thrombinlike proteases which cause slow clotting of fibrinogen, and plasmin-like components causing further proteolysis of fibrinogen and fibrin. Antivenom has no effect on the proteolytic action of the snake venom. The in vivo effects of antivenom are presumably caused by acceleration of the elimination of venom components from the circulation. Intravenous administration of antivenom caused normalization of blood coagulation parameters within 48 h.     

Monitoring platelet dependent thrombin generation in mice

Calibrated automated thrombin generation assay was adapted to measure thrombin generation in platelet rich plasma from mice. Vena cava phlebotomy appeared the best technique for blood sampling. The concentration-effect curves of tissue factor and platelet count have been determined. Corn trypsin inhibitor 2 μM inhibits contact activation effectively. Recombinant human thrombomodulin does not inhibit thrombin generation in mouse plasma but activated protein C (20 nM) does. Thrombin generation was dose dependently diminished by low molecular weight heparin and increased by high concentrations of exogenous factor VIII i.e. the assay can detect both hypo- and hypercoagulability.     

Continuous thrombin infusion leads to a bleeding phenotype in sheep

Background

In addition to a recognized role in the coagulation cascade and haemostasis, thrombin is known to have multiple functions. We aimed to establish an ovine model to study thrombin effects in vivo.

Methods

Thrombin (0.0004-0.42 IU/kg/min) was continuously infused in Austrian Mountain Sheep over five hours in the dose escalation study (n = 5 animals; 15 experiments). In the dose verification study animals received 0.42 IU/kg/min of thrombin vs. saline solution in a cross-over design (n = 3 animals; 7 experiments).

Results

Thrombin at an infusion rate of 0.42 IU/kg/min decreased fibrinogen levels by 75% (p < 0.001) and increased degradation products of the fibrinogen beta-chain as shown in a proteomic analysis. Thrombin decreased platelet counts by 36% (p = 0.006), prolonged thrombin time by 70% (p = 0.012) and activated partial thromboplastin time by 32%. Interestingly, thrombin infusion significantly increased the activity of coagulation factors V and X (p < 0.05) and decreased the activity of the coagulation factors VIII and XIII (p < 0.05). Accordingly, thrombin displayed predominantly anti-coagulant and anti-platelet effects: 1) thrombin prolonged clotting time/clot formation time 7-fold (p = 0.019) and induced a 65% decrease in maximal clot firmness (p < 0.001); 2) thrombin reduced collagen- induced platelet aggregation by 85% and prolonged collagen/adenosine diphosphate closure time 3-fold; and 3) thrombin caused lung haemorrhage but not thromboembolism.

Conclusion

Protracted intravenous infusion of thrombin over a period of five hours offers a new experimental model to study thrombin effects in a large animal species.     

RhoA蛋白参与凝血酶对胎鼠大脑皮层神经元的损伤

目的 探讨凝血酶诱导的胎鼠大脑皮层神经元损伤与RhoA蛋白活化表达的关系.方法 体外培养胎鼠大脑皮层神经元8d后,采用Western blotting检测不同浓度凝血酶(0、1、10、30和100 U/mL)作用3h后及30 U/mL凝血酶作用不同时间(0、0.5、1、3和6h)对皮层神经元RhoA蛋白活化表达的影响;RhoA蛋白活化抑制剂Exoenzyme C3预处理0.5 h及30 U/mL凝血酶作用皮层神经元3h后,行Western blotting检测RhoA蛋白活化表达的情况,并采用Hoechst33258核染色及CCK-8法观察Exoenzyme C3预处理和未处理时凝血酶对皮层神经元的损伤情况. 结果 在浓度实验中,30 U/mL凝血酶作用皮层神经元3h后能明显增加RhoA膜蛋白表达,与0U/mL组相比差异有统计学意义(P＜0.05);而各浓度凝血酶对RhoA总蛋白表达无明显影响.在时程实验中,与其他时间点相比,30 U/mL凝血酶在3h时能明显增加RhoA膜蛋白表达,差异有统计学意义(P＜0.05),但对RhoA总蛋白表达也无明显影响.在Exoenzyme C3干预实验中,Exoenzyme C3预处理组与凝血酶组相比,RhoA膜蛋白表达明显降低,差异有统计学意义(P＜0.05);Hoechst3258核染色显示,与凝血酶组相比,Exoenzyme C3预处理组中核浓染细胞数量明显降低,差异有统计学意义(P＜0.05);CCK-8法检测细胞活性显示,凝血酶组细胞存活率明显低于Exoenzyme C3预处理组,差异有统计学意义(P＜0.05). 结论 凝血酶诱导的胎鼠大脑皮层神经元损伤与RhoA膜蛋白的高表达即RhoA蛋白活化表达有关.     

血浆中PAI-1和TAFI水平与溶栓后出血性转化相关性研究

目的探索PAI及TAFI对急性脑梗死静脉溶栓后出血性转化的预警作用。方法前瞻性的将溶栓患者分为出血转化组和无出血转化组,对两组患者溶栓前及溶栓后静脉血浆PAI及TAFI浓度进行对比及统计学分析。结果溶栓前两组基线PAI-1水平差异有明显统计学意义(P=0.037)。溶栓后次日复查晨血PAI-1水平出血转化组明显较无出血转化组值更低(P=0.035)。溶栓前出血转化组的基线TAFI水平较无出血转化组比较TAFI值更低(P=0.024)。溶栓后次日复查晨血出血转化组TAFI值同样低于无出血转化组(P=0.042)。结论血浆中PAI-1和TAFI水平与溶栓后出血性转化相关性较高。当溶栓前及溶栓后PAI-1及TAFI的低水平表达均可增加溶栓后出血性转化的风险。     

大鼠脑出血后脑组织蛋白酶连接素-1、凝血酶和蛋白酶激活受体-1表达变化的实验研究

目的 研究大鼠实验性脑出血后脑组织内蛋白酶连接素-1(PN-1)、凝血酶及蛋白酶激活受体-1(PAR-1)的表达及变化规律. 方法采用自体血注入法制备大鼠脑出血模型,Westernblot方法检测假手术组及脑出m模型组不同时程(3 h、6 h、10 h、12 h、24 h、48 h、120 h)PN-1、凝血酶和PAR-1蛋白的表达水平. 结果假手术组可以检测到少量PN-1、凝血酶和PAR-1蛋白的表达;PN-1于脑出血后3 h开始增加,此后持续上升,10 h达高峰,后逐渐回降;凝血酶于脑出血后12h显著增加,48 h达高峰;PAR-1于脑出血后3 h即显著增加,48 h达高峰,120 h仍处于较高水平.脑出血后各时间点PN-1、凝血酶和PAR-1蛋白的表达量与假手术组比较,差异均具有统计学意义(P<0.05).PN-1与PAR-1在脑出血后10h时呈负相关(r=-0.900,P<0.05),PN-1与凝血酶在脑出血后12h、120h时呈负相关(r=-0.900,P<0.05:r=-0.895,P<0.05). 结论脑出血后增多的凝血酶通过不断激活PAR-1从而介导了脑出血后的神经损伤过程,与此同时凝血酶抑制剂PN-1也大量表达,一定程度上抑制凝血酶过表达所引起的毒性效应:脑出血后三种蛋白的表达增加可能与脑出血后神经损伤的发病机制有关.     

尿激酶型纤溶酶原激活剂诱发的纤溶反应及其调节因子

目的 研究一些凝血和纤溶因子对尿激酶型纤溶酶原激活剂（uPA)诱发纤溶反应的调节作用及机制。方法 采用凝块溶解测定和纤维蛋白检测板测定观察了一些凝血和纤溶因子对uPA诱导的纤溶反应的影响及相互作用。结果 凝血酶激活的纤溶抑制因子（TAFI）对uPA或单链uPA（scuPA）诱发的纤溶反应具有明显的拮抗作用，凝血酶调节因子（TM）可明显增强其抑制作用，凝血酶对uPA诱导的纤溶反应没有明显的影响，但可抑制scuPA诱导的纤溶反应，该作用亦可被TM所增强或被水蛭素所消除。结论 凝血酶／TM可通过激活TAFI对uPA或scuPA诱导的纤溶反应产生抑制作用，凝血酶对scuPA诱发的纤溶反应的抑制作用亦可通过其对scuPA的裂解失活而实现。     

阿加曲班对脑血管支架置入术后支架内再狭窄影响的随机对照研究

目的 探讨阿加曲班对脑血管支架置入术后支架内再狭窄发生的影响. 方法 设计一项前瞻性随机对照试验:选取自2010年8月至201 1年8月南京军区总医院神经内科收治的适合行脑血管支架置入术的患者110例,按随机数字表法分为阿加曲班组及对照组.阿加曲班组从术前2d到术后3d连续接受20 mg阿加曲班静脉滴注治疗,对照组不进行阿加曲班治疗,2组其余药物治疗相同.阿加曲班组患者给药前及用药2h后采血监测凝血功能.对患者在术后1月、3月、6月、9月门诊随访,6～9月住院复查DSA;以支架内再狭窄为主要终点事件,以目标血管重建、脑卒中复发、心血管事件、死亡及出血事件为次要终点事件. 结果 安全性结果:阿加曲班组患者围手术期间无出血事件、过敏反应及肝功能障碍的发生.有效性结果:(1)阿加曲班组发生支架内再狭窄率(9.3％)明显低于对照组(24％),差异有统计学意义(P=0.042).(2)阿加曲班组目标血管重建率(5.5％)低于对照组(14.5％),但差异无统计学意义(P=0.202).(3)围手术期间和术后随访9月2组次要终点事件发生率(脑卒中复发、心血管事件、死亡事件)比较差异均无统计学意义(围手术期:x2=3.336,P=0.108;x2=1.090,P=0.481);术后9月:x2=1.193,P=0.527; x2=0.003,P=1.000;x2=1.090,P=0.481). 结论 阿加曲班可安全有效地预防脑血管支架置入术后支架内再狭窄的发生,不增加出血等不良事件.     

Percutaneous Repair of Radial Artery Pseudoaneurysm in a Hemodialysis Patient Using Sonographically Guided Thrombin Injection

We report a case of a radial artery pseudoaneurysm complicating an incorrect puncture of a Brescia-Cimino hemodialysis fistula that was treated with percutaneous ultrasound-guided thrombin injection. The pseudoaneurysm recurred after the initial successful thrombin injection. With a second injection we obtained permanent pseudoaneurysm occlusion. Our case illustrates that this procedure is an effective treatment in this type of arteriovenous fistula complication. We compare this case with the only similar one we could find in the literature.     

水蛭提取液对凝血酶引起的体外星形胶质细胞毒性损害的保护作用研究

目的 探讨凝血酶对培养的大鼠脑星形胶质细胞毒性损害及水蛭提取液对其的保护作用. 方法 建立体外实验即大鼠脑星形胶质细胞培养实验模型,相差显微镜观察细胞生长状况.MTT法筛选水蛭提取液的有效浓度.星形胶质细胞分为水蛭提取液治疗组与凝血酶对照组,测定培养上清液酸脱氢酶(LDH)活性(细胞死亡的标志).免疫组化法观察它们的HSP70和TGFβ-1的表达. 结果 (1)一定浓度范同(1～100 U/mL)的凝血酶对星形胶质细胞有毒性作用,且随凝血酶剂量的增大,它对星形胶质细胞的毒性作用相应增加(F=118.65,P=0.000).(2)一定浓度范围内(0.25～4 mg/μL)的水蛭提取液能明显减轻10 U/mL凝血酶对星形胶质细胞的毒性作用(F=156.08,P=0.000),且随水蛭提取液浓度的增大,保护作用增强,还可促进星形胶质细胞HSP70和TGFβ-1的表达. 结论 水蛭提取液能促进星形胶质细胞增生,增强它们的HSP70和TGFβ-1表达,从而明显抑制凝血酶对星形胶质细胞的毒性作用.