Nonproteolytic neuroprotection by human recombinant tissue plasminogen activator

Human recombinant tissue plasminogen activator (tPA) may benefit ischemic stroke patients by dissolving clots. However, independent of thrombolysis, tPA may also have deleterious effects on neurons by promoting excitotoxicity. Zinc neurotoxicity has been shown to be an additional key mechanism in brain injuries. Hence, if tPA affects zinc neurotoxicity, this may provide additional insights into its effect on neuronal death. Independent of its proteolytic action, tPA markedly attenuated zinc-induced cell death in cortical culture, and, when injected into cerebrospinal fluid, also reduced kainate seizure-induced hippocampal neuronal death in adult rats.     

Medicine. Stroke--tPA and the clinic

Clinical trial results are not always rapidly incorporated into routine medical practice. This Policy Forum describes a variety of barriers that have impeded the more widespread use of thrombolytic therapy (tPA, tissue plasminogen activator) for selected patients with acute ischemic stroke. These barriers are not insurmountable but will require a concerted effort to overcome.     

Chromosomal locations of human tissue plasminogen activator and urokinase genes

A panel of human-mouse somatic cell hybrids and specific complementary DNA probes were used to map the human tissue plasminogen activator and urokinase genes to human chromosomes 8 and 10, respectively. This result is in contrast to a previous assignment of a plasminogen activator gene to chromosome 6. As neoplastic cells produce high levels of plasminogen activator, it is of interest that aberrations of chromosome 8 have been linked to various leukemias and lymphomas and that two human oncogenes, c-mos and c-myc, have also been mapped to chromosome 8.     

Cleavage of proBDNF by tPA/plasmin is essential for long-term hippocampal plasticity

Long-term memory is thought to be mediated by protein synthesis-dependent, late-phase long-term potentiation (L-LTP). Two secretory proteins, tissue plasminogen activator (tPA) and brain-derived neurotrophic factor (BDNF), have been implicated in this process, but their relationship is unclear. Here we report that tPA, by activating the extracellular protease plasmin, converts the precursor proBDNF to the mature BDNF (mBDNF), and that such conversion is critical for L-LTP expression in mouse hippocampus. Moreover, application of mBDNF is sufficient to rescue L-LTP when protein synthesis is inhibited, which suggests that mBDNF is a key protein synthesis product for L-LTP expression.     

结肠癌组织中中期因子、尿激酶型纤溶酶原激活物的表达及意义

目的了解结肠癌组织中中期因子（MK）、尿激酶型纤溶酶原激活物（uPA）表达及其与结肠癌临床病理特征的关系。方法收集55例病理学确证的结肠癌组织标本（病例组）和30例结肠癌癌旁的正常组织标本（对照组）,采用免疫组织化学方法（SP法）检测其MK、uPA的表达。结果病例组中MK、uPA表达率分别为56.36%、61.82%,对照组分别为13.33%、16.67%,两组的差异均有统计学意义（P〈0.01）。结肠癌组织中MK、uPA表达与癌组织的分化程度、浸润深度、淋巴结转移有相关性,而与性别和年龄无相关性。MK与uPA表达呈正相关（r=0.44,P〈0.05）。结论 MK、uPA表达与结肠癌侵袭、转移密切相关,二者联合检测可作为判断结肠癌发展及预后的指标。     

Fluid flow stimulates tissue plasminogen activator secretion by cultured human endothelial cells

Wall shear stress generated by blood flow may regulate the expression of fibrinolytic proteins by endothelial cells. Tissue plasminogen activator (tPA) and plasminogen activator inhibitor, type 1 (PAI-1) secretion by cultured human endothelial cells were not affected by exposure to venous shear stress (4 dynes/cm2). However, at arterial shear stresses of 15 and 25 dynes/cm2, the tPA secretion rate was 2.1 and 3.0 times greater, respectively, than the basal tPA secretion rate. PAI-1 secretion was unaffected by shear stress over the entire physiological range.     

Tick anticoagulant peptide (TAP) is a novel inhibitor of blood coagulation factor Xa

A low molecular weight serine protease inhibitor (TAP) was purified from extracts of the soft tick, Ornithodoros moubata. The peptide is a slow, tight-binding inhibitor, specific for factor Xa (Ki = 0.588 +/- 0.054 nM). The inhibitor also acts as an anticoagulant in several human plasma clotting assays in vitro. Its amino acid sequence (60 residues) has limited homology to the Kunitz-type inhibitors. However, unlike other inhibitors of this class, TAP inhibits only factor Xa. It had no effect at a 300-fold molar excess on factor VIIa, kallikrein, trypsin, chymotrypsin, thrombin, urokinase, plasmin, tissue plasminogen activator, elastase, or Staphylococcus aureus V8 protease. TAP's specificity and size suggest that it may have therapeutic value as an anticoagulant.     

桥接治疗急性缺血性脑卒中患者的血管再通率及远期神经功能恢复分析

目的 探讨重组组织型纤溶酶原激活物（rtPA）静脉溶栓联合血管内介入治疗（即桥接治疗法）对急性缺血性脑卒中患者的治疗效果。方法 选取我院（2015年1月-2018年1月）收治的100例急性缺血性脑卒中患者进行回顾性分析,根据治疗方法分为观察组47例（桥接治疗法）、对照组53例（rtPA静脉溶栓疗法）,对比两组治疗后的血管再通率、神经功能恢复情况。结果 观察组前循环梗死血管（颈内动脉、大脑前动脉、大脑中动脉）再通率91.49%,对照组前循环梗死血管再通率50.94%,两组比较差异具有统计学意义（P<0.01）;观察组治疗14 d、治疗28 d、治疗3个月,神经功能缺损（NIHSS）评分均显著的低于对照组（P<0.01）;根据mRS标准,观察组的预后良好87.23%,对照组预后良好52.83%,两组比较差异具有统计学意义（P<0.01）;观察组的并发症发生率8.51%,对照组并发症发生率16.98%,两组比较差异无统计学意义（P>0.05）。结论 桥接治疗对缺血性脑卒中患者的效果优于rtPA静脉溶栓疗法,对于患者远期神经功能恢复具有显著效果。     

Targets for dioxin: genes for plasminogen activator inhibitor-2 and interleukin-1 beta

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD), a widespread environmental contaminant, may elicit its effects by altering gene expression in susceptible cells. Five TCDD-responsive complementary DNA clones were isolated from a human keratinocyte cell line. One of these clones encodes plasminogen activator inhibitor-2, a factor that influences growth and differentiation by regulating proteolysis of the extracellular matrix. Another encodes the cytokine interleukin-1 beta. Thus, TCDD alters the expression of growth regulatory genes and has effects similar to those of other tumor-promoting agents that affect both inflammation and differentiation.     

组织型纤溶酶原激活剂cDNA真核表达质粒的构建与鉴定

将组织型纤溶酶原激活剂基因ｃＤＮＡ经多次亚克隆插入到真核表达载体ｐＳＶＬ的ＳＶ４０启动子和ｐｃＤＮＡ３的ＣＭＶ启动子下游,构建了重组表达质粒ｐＳＶＬ－ｔＰＡ和ｐｃＤＮＡ３－ｔＰＡ。经酶切和Ｓｏｕｔｈｅｒｎ杂交鉴定,ｔ－ＰＡ基因的插向正确,可用于哺乳动物细胞和个体表达系统中表达。     

Shear-activated nanotherapeutics for drug targeting to obstructed blood vessels

Obstruction of critical blood vessels due to thrombosis or embolism is a leading cause of death worldwide. Here, we describe a biomimetic strategy that uses high shear stress caused by vascular narrowing as a targeting mechanism--in the same way platelets do--to deliver drugs to obstructed blood vessels. Microscale aggregates of nanoparticles were fabricated to break up into nanoscale components when exposed to abnormally high fluid shear stress. When coated with tissue plasminogen activator and administered intravenously in mice, these shear-activated nanotherapeutics induce rapid clot dissolution in a mesenteric injury model, restore normal flow dynamics, and increase survival in an otherwise fatal mouse pulmonary embolism model. This biophysical strategy for drug targeting, which lowers required doses and minimizes side effects while maximizing drug efficacy, offers a potential new approach for treatment of life-threatening diseases that result from acute vascular occlusion.     

人组织型纤溶酶原激活剂原核表达载体的构建及在大肠杆菌中的初步表达

目的:构建人组织型纤溶酶原激活剂(tissue-type plasminogen activator,tPA)原核表达载体,检测其在大肠杆菌Escherichia coli中的初步表达.方法:以含有人tPA基因的质粒为模板,设计引物扩增出含有RGDS-tPA基因并构建到原核表达载体pET28a中,测序证实为正确的rtPA序列,并将pET28a-tPA转化至菌株E.coli BL21(DE3).用IPTG诱导rtPA在E.coli中表达,并通过聚丙烯酰胺凝胶电泳(SDS-PAGE)进行验证.结果:琼脂糖凝胶电泳获得目的基因片段tPA的条带约在1 700bp处,鉴定为阳性重组体;聚丙烯酰胺凝胶电泳鉴定获得目的蛋白片段rtPA的条带约53KDa,为非活性的包涵体.结论:人组织型纤溶酶原激活剂原核表达载体构建成功,可在大肠杆菌中有效表达.     

芽孢杆菌纤溶酶的纯化及其生物活性研究

芽孢杆菌2^#（Bs-2）的发酵液经过硫酸铵分级沉淀、Sephadex G-75凝胶过滤层析、Q-Sepharose阴离子交换层析、电泳制备和电源洗脱。获得一种具有纤溶性的蛋白酶;该蛋白酶由3个亚基组成,分子量分别为23KD,SSKD,19KD,全酶分子量约为64KD;经纤维蛋白平板测定表明,该酶既具有纤溶酶作用,又具有激活纤溶酶原的作用。     

信号传导与转录活化因子3在肝细胞癌组织中的表达及意义

目的 研究信号传导与转录活化因子3(STAT3)在肝细胞癌组织中的表达及其意义.方法 分别应用逆转录聚合酶链式反应(RT-PCR)和免疫组织化学法检测肝癌组织、癌旁组织和良性病变肝组织中STAT3 mRNA和蛋白的表达,应用免疫组织化学法检测Bcl-xL的蛋白表达情况.结果 肝癌组织、癌旁组织中STAT3 mRNA的相对表达量和蛋白阳性率均高于良性病变肝组织(P均<0.01或0.05).肝癌组织及癌旁组织中Bcl-xL蛋白表达率明显高于良性病变肝组织(P<0.05).肝癌组织中STAT3蛋白与Bcl-xL蛋白表达有密切关系(P<0.01).结论 STAT3高表达可能是肝癌发病机制中的早期事件;在癌旁肝组织中,那些STAT3蛋白阳性的肝细胞可能是潜在的癌前细胞.STAT3基因可能通过直接或间接促进Bcl-xL的表达,抑制细胞的凋亡,从而在肿瘤的发生发展过程中发生重要作用.     

Functional innervation of hepatic iNKT cells is immunosuppressive following stroke

Systemic immunosuppression has been associated with stroke for many years, but the underlying mechanisms are poorly understood. In this study, we demonstrated that stroke induced profound behavioral changes in hepatic invariant NKT (iNKT) cells in mice. Unexpectedly, these effects were mediated by a noradrenergic neurotransmitter rather than a CD1d ligand or other well-characterized danger signals. Blockade of this innervation was protective in wild-type mice after stroke but had no effect in mice deficient in iNKT cells. Selective immunomodulation of iNKT cells with a specific activator (α-galactosylceramide) promoted proinflammatory cytokine production and prevented infections after stroke. Our results therefore identify a molecular mechanism that leads to immunosuppression after stroke and suggest an attractive potential therapeutic alternative to antibiotics, namely, immunomodulation of iNKT cells to prevent stroke-associated infections.     

Antisense RNA directed against the 3' noncoding region prevents dormant mRNA activation in mouse oocytes

Primary mouse oocytes contain untranslated stable messenger RNA for tissue plasminogen activator (t-PA). During meiotic maturation, this maternal mRNA undergoes a 3'-polyadenylation, is translated, and is degraded. Injections of maturing oocytes with different antisense RNA's complementary to both coding and noncoding portions of t-PA mRNA all selectively blocked t-PA synthesis. RNA blot analysis of t-PA mRNA in injected, matured oocytes suggested a cleavage of the RNA.RNA hybrid region, yielding a stable 5' portion, and an unstable 3' portion. In primary oocytes, the 3' noncoding region was susceptible to cleavage, while the other portions of the mRNA were blocked from hybrid formation until maturation occurred. Injection of antisense RNA complementary to 103 nucleotides of its extreme 3' untranslated region was sufficient to prevent the polyadenylation, translational activation, and destabilization of t-PA mRNA. These results demonstrate a critical role for the 3' noncoding region of a dormant mRNA in its translational recruitment during meiotic maturation of mouse oocytes.     

Lactones as inhibitors of the fibrinolytic system

Caprolactone, valerolactone, and butyrolactone inhibit proteolytic and fibrinolytic activities of human plasmin. In very low concentrations, they also inhibit activation of plasminogen through plasmin-streptokinase activator and human urokinase. The degree of inhibitory potency depends upon the number of carbon atoms in the lactone.     

利用重叠延伸PCR技术进行定点突变研究

[目的]建立一种高效、便捷、经济的DNA定点突变方法。[方法]以重组人组织型纤溶酶原激活剂rPA(Reteplase)基因为模板,采用重叠延伸PCR技术对3个位点进行定点突变,将突变基因片段克隆到克隆载体pEASY-Blunt上,并通过测序验证突变结果。[结果]测序结果表明3个位点的突变结果与预期完全一致,即第10位引入单个碱基A、第137位碱基C突变为G以及第686位碱基G突变为A,通过重叠延伸PCR技术一次引入3个突变碱基,100%的实现目的位点的定点突变。[结论]该研究成功实现目的位点的定点突变,为rPA基因的进一步克隆和功能研究奠定了基础。同时也表明重叠延伸PCR技术是一种高效、便捷、经济的DNA定点突变方法。     

利用重叠延伸PCR技术进行定点突变研究(英文)

[目的]建立一种高效、便捷、经济的DNA定点突变方法。[方法]以重组人组织型纤溶酶原激活剂rPA(Reteplase)基因为模板,采用重叠延伸PCR技术对3个位点进行定点突变,将突变基因片段克隆到克隆载体pEASY-Blunt上,并通过测序验证突变结果。[结果]测序结果表明3个位点的突变结果与预期完全一致,即第10位引入单个碱基A、第137位碱基C突变为G以及第686位碱基G突变为A,通过重叠延伸PCR技术一次引入3个突变碱基,100%的实现目的位点的定点突变。[结论]该研究成功实现目的位点的定点突变,为rPA基因的进一步克隆和功能研究奠定了基础。同时也表明重叠延伸PCR技术是一种高效、便捷、经济的DNA定点突变方法。     

Innovative approaches to plasminogen activator therapy

Plasminogen activator therapy for acute myocardial infarction has become standard medical practice. Bleeding complications, however, limit the utility of the currently available agents. This article reviews how the tools of molecular biology and protein engineering are being used to develop safer and more effective plasminogen activators.