Relationship between tissue plasminogen activator and the activators in blood and vascular wall

To explore the relation between tissue plasminogen activator and both vascular and blood fibrinolytic activity, an antiserum against a tissue plasminogen activator, recently purified from human uterus, was used. By measuring the extent of quenching of fibrinolytic activities by the IgG fraction of this antiserum immunological relationship with tissue plasminogen activator was established. Thus, the plasminogen activator activity in the vascular wall, responsible for the lysis in Todd's fibrin slide technique and released by perfusion of a cadaver limb was completely identified as tissue plasminogen activator activity. In addition, a part of the fibrinolytic activity of blood which was notably enhanced after venous occlusion or physical exercise was attributed to tissue plasminogen activator related activity. The intrinsic activators/proactivators in blood were found to be immunologically unrelated to tissue plasminogen activator. By immunoadsorption chromatography tissue plasminogen activator related activator was isolated from venous occlusion plasma. Comparison with the uterine tissue plasminogen activator showed that both activators had similar immunological properties, temperature stabilities, and molecular weights on dodecylsulphate polyacrylamide gel electrophoresis besides a small difference on gel filtration. These close similarities support the hypothesis that plasminogen activator is synthesized in the vascular wall and released into the circulating blood.     

重组组织型纤溶酶原激活剂动脉溶栓联合丹红 注射液对急性脑梗死患者血清神经细胞因子和 炎性因子水平的影响

目的 探讨重组组织型纤溶酶原激活剂(rt-PA)动脉溶栓联合丹红注射液对急性脑梗死(ACI)患者血清神经细胞因子和炎性因子水平的影响。方法 选取2016年2月-2017年10月在安阳市第三人民医院神经内科接受治疗的ACI患者80例,根据乱数表法将其分为对照组(n=40)和观察组(n=40); 对照组采用rt-PA动脉溶栓治疗,观察组采用rt-PA动脉溶栓联合丹红注射液进行治疗; 比较2组患者的治疗效果、神经功能缺损程度(NFDS)评分、Barthel评分、神经元特异性烯醇化酶(NSE)、S-100β蛋白、白介素-6(IL-6)、C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)水平,观察2组患者的不良反应发生率。结果 观察组的有效率为82.50%(33/40),明显高于对照组的62.50%(25/40)(P<0.05); 治疗24 h后、治疗7、14 d后2组患者的NFDS评分均低于治疗前,Barthel评分均高于治疗前(P<0.05),在治疗24 h后、治疗7、14 d后观察组的NFDS评分均低于对照组,Barthel评分均高于对照组(P<0.05); 治疗14 d后2组患者血清中的NSE和S-100β水平均低于治疗前,且观察组患者血清中的NSE和S-100β水平均低于对照组(P<0.05); 治疗14 d后2组患者血清中的IL-6、CRP、TNF-α水平低于治疗前,且观察组患者血清中的IL-6、CRP、TNF-α水平低于对照组(P<0.05); 2组患者的不良反应发生率比较无明显差异(P>0.05)。结论 rt-PA动脉溶栓联合丹红注射液治疗可以显著改善ACI患者神经功能缺损程度和生活能力,降低血清中神经细胞因子和炎性因子水平,具有较好的临床疗效。     

Changes of the fibrinolytic system of animals induced by injection of tissue plasminogen activator

The changes in the fibrinolytic system of rats induced by repeated injections of tissue plasminogen activator (TPA) have been studied. The euglobulin fraction fibrinolytic activity increases 10 min after the first injection of TPA. Repeated injections of TPA for one or more days do not stimulate the fibrinolytic activity or TPA accumulation in the blood. Apparently in the absence of fibrin clots in the blood flow of healthy animals TPA is incapable of activating plasminogen conversion into plasmin. TPA, in its turn, is rapidly bound to the antiactivator and is excreted from the organism.     

重组组织型纤溶酶原激活剂治疗脑室内出血

目的 探讨利用重组组织型纤溶酶原激活剂(rt-PA)脑室内给药治疗脑室出血的疗效和安全性. 方法 对自2005年11月至2007年10月收入我院的10例脑室出血患者CT确诊后,进行(单侧或双侧)脑室穿刺置管,4～6 h后经弓l流管缓慢注入rt-PA 4～8 mg,12～24 h重复1次,每24～48小时复查CT了解脑室内血肿清除情况,直至头颅CT扫描显示脑室内高密度影像消失.于脑室出血后30 d时对患者情况利用GOS评分进行评估. 结果 每个患者应用rt-PA总剂量为13～24 mg,30 d后GOS评分为良好4例,中残3例,重残2例,植物生存1例,无患者死亡,无出血、颅内感染等并发症,未发生引流管被血块堵塞情况. 结论 选择适宜剂量和方法的rt-PA脑室内给药能够加速脑室内血块溶解,保持脑室引流管通畅,减少血块占位效应.该方法能够安全有效地改善患者的预后.     

An ischemic stroke during intravenous recombinant tissue plasminogen activator infusion for evolving myocardial infarction

A 56-year-old man without a previous history of stroke received intravenous recombinant tissue plasminogen activator (tPA) for an evolving myocardial infarction. During the infusion, the patient developed aphasia and right hemiparesis. The CT and MRI confirmed an ischemic stroke without evidence of hemorrhage. Although the cerebral hemorrhage after tPA infusion is relatively more common, in rare cases, tPA infusion may result in fragmentation of a cardiac thrombus resulting in an ischemic cerebral stroke.     

依达拉奉联合重组组织型纤溶酶原激活剂治疗急性脑梗死的效果分析

目的探讨依达拉奉联合重组组织性纤溶酶原激活剂治疗急性脑梗死的临床效果。方法选择于我院就诊发病6h内的急性脑梗死保守治疗70例,随机分为研究组(n=35)和对照组(n=35),研究组采用依达拉奉联合重组组织纤溶酶原激活剂治疗,对照组仅采用重组组织纤溶酶原激活剂治疗。比较2组治疗前后的神经功能缺损评分、脑缺血组织血管再通率、不良反应发生率。结果治疗前2组神经功能缺损评分差异无统计学意义(P0.05),治疗后研究组神经功能缺损评分显著低于对照组(P0.05),脑缺血组织血管再通率显著高于对照组(P0.05),2组不良反应发生率差异无统计学意义(P0.05)。结论依达拉奉联合重组组织型纤溶酶原激活剂治疗急性脑梗死患者效果显著,能显著改善患者的神经缺损症状,促进血管再通,值得推广应用。     

The potentiating effect of platelet on plasminogen activation by tissue plasminogen activator

A new role for platelets in fibrinolysis is proposed. Platelets (euglobulin from platelet rich plasma and from human platelet extract) may potentiate plasminogen activation by tissue plasminogen activator(tPA). The potentiating activity was detected by both chromogenic substrate and fibrin plate analysis. The fibrinolysispotentiating substance in the platelets required the presence of both tPA and plasminogen, suggesting that it potentiates the activation of plasminogen by tPA. This substance was not related to fibrinogen degradation products because it was also present in platelets from two afibrinogenemic patients and did not lose its activity when separated from fibrinogen-related antigen by Sepharose 2B gel filtration. Since platelets contain both activator(s) and inhibitor(s) of plasminogen activation by tPA, a balance between activator(s) and inhibitor(s) in platelets may also be required for control of the fibrinolytic pathway.     

Monoclonal antibody to human tissue plasminogen activator

Hybridoma producing a monoclonal antibody IgG₁ to one-chain tissue plasminogen activator (t-PA) derived from human melanoma cells was obtained by fusion of mouse myeloma cells (SP-1) and spleen cells of mice previously immunized with purified t-PA. The monoclonal antibody reacted only with t-PA derived from the human melanoma cells (Bowes), and not with plasminogen activator purified from porcine heart or from human urine. The monoclonal antibody obtained from mouse ascites demonstrated 50 times stronger antibody activity than that of polyclonal antibody obtained from mouse serum. The monoclonal antibody bound t-PA firmly, inhibited the fibrinolytic activity of t-PA, but did not inhibit the amidolytic activity of t-PA completely. The fib-χin-binding ability of t-PA was not inhibited. The binding of monoclonal antibody to the non-reduced form of t-PA did not differ from that to the reduced form of t-PA.     

Systemic hemostasis with recombinant-activated factor VII followed by local thrombolysis with recombinant tissue plasminogen activator in intraventricular hemorrhage

Introduction: A 51-year-old woman on warfarin thromboprophylaxis for transient ischemic attacks developed sudden onset nausea, vomiting, and decreased mental status, rapidly becoming comatose. Head computed tomography (CT) showed intracerebral hemorrhage, extending into all ventricular chambers, and acute obstructive hematocephalus requiring urgent ventricular drainage. CT angiogram showed no evidence of an aneurysm or vascular malformation. Methods: The pretreatment international normalized ratio (INR) of 4.9 was rapidly corrected with recombinant activated factor VII and an external ventricular drain was placed. Despite accurate positioning, the ventriculostomy thrombosed and became nonfunctional. Recombinant tissue plasminogen activator was given intraventricularly and resulted in partial ventricular decompression within 24 hours, with dramatic improvement in the patient’s level of consciousness. Results: Repeated intraventricular fibrinolysis resulted in further reduction of the intraventricular hematoma within a few days and a good patient outcome. The patient did not require permanent ventricular shunt. Conclusion: To our knowledge, this is the first reported case of combined systemic enhancement of hemostasis and local fibrinolysis as a life-saving measure in intracranial hemorrhage.     

重组组织型纤溶酶原激活剂静脉溶栓治疗后循环脑梗死的疗效及安全性评价

目的探讨rt-PA(重组组织型纤溶酶原激活剂)静脉溶栓治疗后循环脑梗死的疗效及安全性。方法选取我院2013-09—2015-09收治的62例后循环脑梗死患者,依据治疗方法不同分为常规组与研究组各31例。常规组予以常规治疗,研究组予以rt-PA溶栓治疗。比较2组治疗前后NIHSS(神经功能缺失评分量表)评分,观察2组临床效果、继发性脑出血率及病死率、血管再闭塞发生情况。结果与常规组比较,研究组治疗后NIHSS评分较低,差异有统计学意义(P0.05);研究组总有效率(93.5%)高于常规组(64.5%),差异有统计学意义(P0.05);2组继发性脑出血、血管再闭塞发生率及病死率比较,差异均无统计学意义(P0.05)。结论 rt-PA溶栓治疗后循环脑梗死,可显著改善患者神经功能,临床效果较为显著,且安全性较高,在临床治疗中具有重要意义。     

Thrombolytic therapy of cerebral arterial occlusion with recombinant tissue plasminogen activator

This report describes three patients, with acute cerebral arterial occlusion, treated with recombinant tissue plasminogen activator (rt-PA). In one patient with basilar artery occlusion thrombolytic treatment was initiated 12 h after onset of the symptoms. In two patients with angiographically verified occlusion of the middle cerebral artery, the treatment was initiated approximately 4.5 h after onset of the symptoms. Recombinant tissue plasminogen activator 80-120 mg, was infused intra-arterially over 90-100 min via a catheter the tip of which was close to the occlusion. This regimen resulted in recanalization in all the patients; however; in two patients it was verified by repeat CT scan only. In two patients the thrombolytic treatment was successful (the patients improved clinically); the third patient died of massive cerebral infarct-related oedema. In none of the patients did significant bleeding or other obvious side-effects occur. From this preliminary report it is concluded that angiographically proven thrombolytic recanalization in acute cerebrovascular occlusion is possible with rt-PA. In some patients, however, the treatment is initiated too late. Further investigation of the possible indication for thrombolytic therapy in stroke is needed.     

Thrombolysis with recombinant tissue plasminogen activator in acute ischemic stroke: evaluation with rCBF-SPECT

We treated five patients with hemispheric ischemic stroke with intravenous recombinant tissue plasminogen activator (rtPA), within 3-6 h after stroke onset. Regional cerebral blood flow was evaluated with single photon emission computed tomography (rCBF-SPECT) before and after treatment. One patient with aphasia and a moderately severe hemiparesis, who had a small flow deficit, was treated 5 h and 30 min after the onset of his stroke and had a prompt and complete recovery. The post treatment rCBF-SPECT showed normal flow. One patient with a very large flow deficit died of transtentorial herniation. In three other patient clinical condition remained unchanged, in one of them despite restoration of flow, demonstrated by transcranial doppler examination. In all these patients the rCBF-SPECT remained abnormal. rCBF-SPECT is a valuable tool in the explanatory analysis of fibrinolytic treatment in ischemic stroke.     

Enhanced tissue plasminogen activator synthesis by the sympathetic neurons that innervate aging vessels

We investigated the source of the increased release of tissue plasminogen activator (t-PA) into the circulation that occurs during natural aging. Both the basal release and the acute stress-associated release induced by sympathetic stimulations are greater in older subjects. It is widely assumed that the source of these increases is vascular endothelium. However, the sympathetic neurons that densely innervate resistance vessel walls were recently shown to synthesize and transport active t-PA to axon terminals in vascular smooth muscle, suggesting an alternative source. These fine t-PA-bearing axons lie in the seldom-studied deep adventitia of vessel walls, where they are less visible than endothelium in tissue sections. Using Northern blot analysis, we observed that t-PAmRNA synthesis is increased 54% in the ganglion parent neuron cell bodies that innervate aged vessels. The t-PA release from isolated, aged ganglia in cultures was twofold greater than that from younger controls. In addition, aged whole-artery explants showed a 20% greater basal and a 50% greater acute release of stored t-PA in vitro. In vivo levels of active t-PA were 33% greater in the blood and 40% greater in the aqueous humor. These results are consistent with an increased infusion of the active t-PA protease from sympathetic axon terminals into the vessel wall extracellular matrix and the blood during natural aging, in addition to the basal endothelial release. We suggest that the cumulative impact of an accelerated plasmin production and matrix degradation within vessel walls, especially during repetitive stress, may play an unrecognized role in the pathogenesis of vascular aging. The possibility that increased sympathetic nervous system plasminogenesis influences the aging process in nonvascular tissues also deserves further investigation.     

不同时间窗重组组织型纤溶酶原激活剂静脉溶栓治疗椎-基底动脉系统脑梗死的疗效

目的探讨不同时间窗重组组织型纤溶酶原激活剂(rt-PA)静脉溶栓治疗椎-基底动脉系统脑梗死的疗效。方法对26例经多模式MRI证实的椎-基底动脉系统脑梗死患者行rt-PA静脉溶栓治疗,治疗时间窗<4.5 h组和4.5～9 h组各13例。患者在治疗前及治疗后24 h、14 d、90 d进行美国国立卫生研究院卒中量表(NIHSS)评分,90 d时行Bathel指数(BI)、改良Rankin量表(mRs)评分,比较两组的疗效;观察溶栓后有无脑出血发生。结果 <4.5 h组与4.5～9 h组各时间点NIHSS、BI及mRs评分差异无统计学意义。<4.5 h组与4.5～9 h组各有1例非症状性脑出血。90 d时,<4.5 h组mRS评分预后良好7例(53.85%);4.5～9 h组6例(46.15%),两组预后良好率的差异无统计学意义。结论椎-基底动脉系统脑梗死静脉rt-PA溶栓治疗4.5 h时间窗和适当延长治疗时间窗均安全有效。     

Thrombolytic therapy with tissue plasminogen activator for prevention of vasospasm in experimental subarachnoid hemorrhage: Its efficacy and problems

Abstract

We investigated the efficacy of two different tissue plasminogen activators (t-PA) for preventing vasospasm after experimental subarachnoid hemorrhage (SAH) in rabbits. Intrathecal injection of Silteplase and Alteplase showed significant preventive action against vasospasm following SAH and thrombolytic effect. The low dose groups with both t-PA showed more preventive action on day 7 than the high dose groups. The data suggest that the determination of optimum dose of t-PA is essential in clinical use of t-PA. [Neurol Res 1996; 18: 342-344]     

Poly-d-lysine dependent inactivation of tissue plasminogen activator by a class pai-2 inhibitor (minactivin)

Two-chain tissue plasminogen activator (t-PA) was found to be inactive in a coupled colorimetric assay for plasminogen activators, but a high level of activity was obtained in the presence of poly-D-lysine. This stimulated activity was strongly inhibited by minactivin, a urokinase inhibitor, but unstimulated enzyme could be shown to be unaffected by minactivin. In the presence of poly-D-lysine minactivin was a very successful competitive inhibitor of t-PA with respect to the substrate, plasminogen. The K_i for minactivin determined by the Henderson method was 2.5 × 10^-12 M, compared to the K_m for plasminogen determined as 0.6 × 10^-6 M. The value of K_i for minactivin with u-PA, determined under the same conditions, was 1.6 × 10^-11 M.     

Secretion of tissue plasminogen activator and plasminogen activator inhibitor 1 during cardiopulmonary bypass

INTRODUCTION: Cardiopulmonary bypass (CPB) is associated with elevated tissue plasminogen activator (t-PA) levels during CPB and increased plasminogen activator inhibitor 1 (PAI-1) levels post-operatively. The goal of this study was to estimate the rate of t-PA and PAI-1 secretion in vivo, before, during and after CPB. MATERIALS AND METHODS: Estimated rates of t-PA and PAI-1 secretion were based on measured levels of active and total t-PA, and active and total PAI-1, obtained before, during and after CPB from nine males, combined with a computer model of each patient's vascular system that continuously accounted for secretion, clearance, hemodilution, blood loss and transfusion. RESULTS AND CONCLUSIONS: At baseline, the average t-PA and PAI-1 secretion rates were 0.74+/-0.33 and 1.28+/-0.74 pmol/s, respectively. Within 5 min of CPB initiation, t-PA secretion increased six-fold to 4.41+/-2.58 pmol/s, while PAI-1 secretion was unchanged, resulting in a six-fold increase in active t-PA levels. t-PA secretion remained elevated throughout CPB and into the early post-operative period. Average PAI-1 secretion did not start to increase until the end of CPB. By 2 h after surgery, average PAI-1 secretion had increased 15-fold to 19.60+/-17.10 pmol/s, resulting in reduced levels of active t-PA even though t-PA secretion was still elevated. We conclude that CPB induces an immediate sustained increase in t-PA secretion followed by a delayed progressive increase in PAI-1 production. Variations in the level of active t-PA are a function of the relative rates of t-PA versus PAI-1 secretion at different times during and after surgery.     

The contribution of -arginine to the neurotoxicity of recombinant tissue plasminogen activator following cerebral ischemia: a review of rtPA neurotoxicity

Alteplase is the only drug licensed for acute ischemic stroke, and in this formulation, the thrombolytic agent recombinant tissue plasminogen activator (rtPA) is stabilized in a solution of -arginine. Improved functional outcomes after alteplase administration have been shown in clinical trials, along with improved histological and behavioral measures in experimental models of embolic stroke. However, in animal models of mechanically induced ischemia, alteplase can exacerbate ischemic damage. We have systematically reviewed the literature of both rtPA and -arginine administration in mechanical focal ischemia. The rtPA worsens ischemic damage under certain conditions, whereas -arginine can have both beneficial and deleterious effects dependent on the time of administration. The interaction between rtPA and -arginine may be leading to the production of nitric oxide, which can cause direct neurotoxicity, altered cerebral blood flow, and disruption of the neurovascular unit. We suggest that alternative formulations of rtPA, in the absence of -arginine, would provide new insight into rtPA neurotoxicity, and have the potential to offer more efficacious thrombolytic therapy for ischemic stroke patients.     

Morphological changes following experimental intraventricular haemorrhage and intraventricular fibrinolytic treatment with recombinant tissue plasminogen activator

Intraventricular haemorrhage (IVH) occurs in up to 50% of patients with primary intracerebral haemorrhage and aneurysmal subarachnoid haemorrhage. It is a significant and independent contributor to mortality and morbidity in these intracranial haemorrhages. Using a model of isolated IVH, we assessed the morphological changes induced by intraventricular bleeding and investigated the effects of intraventricular fibrinolytic treatment following IVH. IVH was induced in 32 pigs by intraventricular infusion of 10 ml autologous blood along with thrombin. The treatment group received an intraventricular injection of 1.5 mg (1 mg/ml) tissue plasminogen activator (tPA) following the injection of blood. The placebo group received the same volume of normal saline. Morphological examinations of the brains were carried out 7 days and 6 weeks following IVH. The ventricles were incompletely filled with blood and significantly enlarged in the placebo group 7 days after the IVH. In contrast, no residual intraventricular clots were visible in the animals treated with tPA, and the diameters of the lateral ventricles had returned to normal within 7 days. Marked losses of the ependymal covering of the ventricular walls were found in the placebo-treated animals, while the ependymal layer was largely intact in the animals treated with tPA. No haemorrhages induced by tPA were observed. The results indicate that intraventricularly administered tPA significantly enhances the lysis of intraventricular blood clots, accelerates the resolution of acute posthaemorrhagic hydrocephalus, and preserves the integrity of the ependymal layer. Received: 6 October 1999 / Revised, accepted: 26 January 2000     

Distribution of sympathetic tissue plasminogen activator (tPA) to a distant microvasculature

Tissue plasminogen activator (tPA) is the predominant plasminogen activator present in the vascular and nervous systems. Prior studies of the two have emphasized different tPA sources; respectively, endothelium and neurons. A closer relationship is now suggested by evidence that the peripheral sympathetic nervous system synthesizes and infuses enzymatically active tPA into small artery walls and the microcirculation. TPA may thus be the only known neural product able to effect degradation of the artery wall extracellular matrix. This brief review considers historical and current indications for the existence of such an autonomically controlled system and some physiologic implications. Immunohistochemical tPA expression in small arteries and arterioles is more prominent in the outer wall sympathetic axon plexus than in endothelium. Its presence in nerve filaments beneath the seldom-studied adventitia was obscured in earlier localizations. The systemic impact of a neural distribution is suggested by a 60% reduction of blood tPA activity after chemical sympathectomy. TPA-bearing axons extend outward from ganglion neuron cell bodies to reach even thin-walled vasa vasora and uveal microvessels. Ganglion cell bodies synthesize and package tPA in vesicles for the long axoplasmic transport. Densely innervated intact vessels release much greater amounts of tPA in vitro than do larger vessels, indicating a high neuron tPA production capacity and a large storage reservoir available within axon networks. The influence of an autonomically controlled plasmin production within small artery walls on regulation of blood pressure and capillary perfusion awaits further investigation. Its possible role in the pathogenesis of vessel wall matrix degradations in aging, hypertension, and diabetes may also merit further consideration.