Effect of human recombinant prourokinase(rhpro-UK) on thromboembolic stroke in rats.

We evaluated the efficacy and safety of human recombinant prourokinase ( rhpro-UK) on thromboembolic stroke in rats. 60 rats with thromboembolic stroke were divided into 6 groups (n = 10). The model group was given saline, the reagent groups were given rhpro-UK (5, 10, 20 × 104U/kg), and positive control groups were given urokinase (UK) 10 × 104U/kg and recombinant tissue plasminogen activator (rt-PA) 9mg/kg through intravenous infusion at 1.5h after embolism. And other 10 rats without occluded by autologous blood clots as the sham group were given saline. At 6h after treatment, neurological deficit score and Magnetic Resonance Imaging(MRI) including T1WI and T2WI sequence scanning were measured. At 24h after treatment, the brain was cut for 2,3,5-triphenyltetrazolium chloride (TTC) staining and aspectrophotometric assay to measure the infarct area and intracerebral hemorrhage after neurological deficit detection. rhpro-UK (5, 10, 20 × 104 U/kg) improved neurological disorder by 39.1 ± 19.7% (n = 10, P > 0.05), 65.2 ± 14.2% (n = 10, P < 0.01) and 65.2 ± 14.2% (n = 10, P < 0.01) maximally; decreased brain lesion volume by 36.7 ± 34.8% (n = 10, P < 0.05), 77.6 ± 7.7% (n = 10, P < 0.01) and 80.5 ± 6.9% (n = 10, P < 0.01); decreased infarction area by 38.2 ± 24.0% (n = 10, P < 0.01), 73.9 ± 5.2% (n = 10, P < 0.001) and 79.7 ± 4.0% (n = 10, P < 0.001) respectively, and there were no statistics difference between rhpro-UK (5, 10, 20 × 104 U/kg) and each positive groups at intracerebral hemorrhage (P > 0.05). Rhpro-UK improved the damaged neural function, decreased the extent of the disease and did not raise bleeding, had protective effects for cerebral ischemia in rats.

Rendering factor Xa zymogen-like as a therapeutic strategy to treat bleeding.

PURPOSE OF REVIEW: New therapies are needed to control bleeding in a range of clinical conditions. This review will discuss the biochemical properties of zymogen-like factor Xa, its preclinical assessment in different model systems, and future development prospects. RECENT FINDINGS: Underlying many procoagulant therapeutic approaches is the rapid generation of thrombin to promote robust clot formation. Clinically tested prohemostatic agents (e.g., factor VIIa) can provide effective hemostasis to mitigate bleeding in hemophilia and other clinical situations. Over the past decade, we explored the possibility of using zymogen-like factor Xa variants to rapidly improve clot formation for the treatment of bleeding conditions. Compared to the wild-type enzyme, these variants adopt an altered, low activity, conformation which enables them to resist plasma protease inhibitors. However, zymogen-like factor Xa variants are conformationally dynamic and ligands such as its cofactor, factor Va, stabilize the molecule rescuing procoagulant activity. At the site of vascular injury, the variants in the presence of factor Va serve as effective prohemostatic agents. Preclinical data support their use to stop bleeding in a variety of clinical settings. Phase 1 studies suggest that zymogen-like factor Xa is safe and well tolerated, and a phase 1b is ongoing to assess safety in patients with intracerebral hemorrhage. SUMMARY: Zymogen-like factor Xa is a unique prohemostatic agent for the treatment of a range of bleeding conditions.

Bioengineering factor Xa to treat bleeding.

There is a clinical need to develop safe and rapid therapeutic strategies to control bleeding arising from a host of emergent situations. Over the past several years our laboratory has developed novel zymogen-like FXa variants and tested their safety and efficacy using hemophilia as a model system. The variants have a spectrum of properties resulting from an amino acid change at the N-terminus of the heavy chain that alters a critical conformational change. These properties, which include resistance to plasma protease inhibitors, low activity in the absence of FVa, and rescue of low activity upon incorporation in prothrombinase, yield remarkably effective pro-hemostatic agents. The FVa-dependent restoration of activity is a key aspect to their efficacy and also contributes to localizing the variants to the site of vascular injury. While pre-clinical data support their use in the setting of hemophilia, they have the potential to act as rapid pro-hemostatic agents for the treatment of a range of bleeding conditions. This review will discuss the biochemical properties of these FXa zymogen-like variants and their in vivo characterization.

Protein C zymogen in adults with severe sepsis or septic shock.

INTRODUCTION: Activated protein C is associated with a risk of bleeding and its effects on survival in septic shock patients are questionable. Protein C zymogen has no risk of bleeding and improves the outcome of patients with septic shock. We hereby describe the largest published case series of adult patients receiving protein C zymogen. DESIGN, SETTING AND PARTICIPANTS: A prospective study on 23 adult patients with severe sepsis or septic shock, two or more organ failures and at high risk for bleeding, treated with protein C zymogen (50IU/kg bolus followed by continuous infusion of 3IU/kg/h for 72h). RESULTS: The Z-test evidenced a significant reduction between the expected mortality (53%) and the observed mortality 30% (Z value=1.99, p=0.046) in our sample population. Protein C levels increased from 34±18% to 66±22% at 6h after PC bolus (p<0.001), and kept on increasing during 72h of administration (p<0.001 to baseline). Sequential Organ Failure Assessment (SOFA), score of organ dysfunction, decreased from baseline to 7 days after administration of protein C from 14±2 to 7±4 (p<0.001). No adverse event drug related was noted. CONCLUSION: Protein C zymogen administration is safe and its use in septic patients should be investigated through a randomized controlled trial.

A zymogen-like factor Xa variant corrects the coagulation defect in hemophilia.

Effective therapies are needed to control excessive bleeding in a range of clinical conditions. We improve hemostasis in vivo using a conformationally pliant variant of coagulation factor Xa (FXa(I16L)) rendered partially inactive by a defect in the transition from zymogen to active protease. Using mouse models of hemophilia, we show that FXa(I16L) has a longer half-life than wild-type FXa and does not cause excessive activation of coagulation. Once clotting mechanisms are activated to produce its cofactor FVa, FXa(I16L) is driven to the protease state and restores hemostasis in hemophilic animals upon vascular injury. Moreover, using human or murine analogs, we show that FXa(I16L) is more efficacious than FVIIa, which is used to treat bleeding in hemophilia inhibitor patients. FXa(I16L) may provide an effective strategy to enhance blood clot formation and act as a rapid pan-hemostatic agent for the treatment of bleeding conditions.

Zymogen Protein C to prevent clotting without bleeding during invasive medical procedures.

Thrombophilic disorders that predispose patients to develop blood clots can be life-threatening and result in a large economic burden on healthcare expenditures. Venous Thromboembolism(VTE) (deep vein thrombosis and pulmonary embolism) are the third leading cause of death in the United States. Protein C deficiency is a common thrombophilic condition that affects an estimated 1 in 400 Americans. Zymogen Protein C (ZPC) is the precursor to Activated Protein C (APC), a pivotal endogenous anticoagulant in human blood. Patients with protein C deficiency who have roughly half the normal level of protein C are estimated to be at 10-fold increased risk of VTE. We describe the use of protein C concentrate (Ceprotin®, Baxter, Deerfield, IL) in a patient with protein C deficiency and with a previous pulmonary embolism who developed a life-threatening gastrointestinal bleed after polypectomy. The patient is a 75-year-old male at very high risk for deep vein thrombosis and possible lung emboli. He has heterozygous Protein C deficiency (50%) and heterozygosity for the prothrombin gene G20210A mutation. During a routine colonoscopy, a large 3 cm cecal polyp was identified and resected. Eight days post-procedure while performing abdominal exercise he developed a life-threatening GI bleed originating from the polypectomy site as his warfarin was becoming therapeutic on a Low Molecular Weight Heparin (LMWH) periprocedural bridge. The patient's warfarin was reversed with vitamin K, and LMWH and warfarin were discontinued. To prevent thrombosis, he was started on ZPC until anticoagulation could be safely restarted. During endoscopy, the bleeding site was treated with an injection of 1:10,000 dilution of epinephrine, followed by cauterization and placement of endoclips (4 metal staples). Three days after endoscopic repair LMWH was restarted with warfarin. Sixteen months post-bleed, the patient remains on life-long warfarin without further episodes of bleeding or thrombosis. Zymogen Protein C concentrate (Ceprotin®, Baxter Deerfield, IL) should be strongly considered for peri-procedural management of any patient with protein C deficiency and previous thromboembolism.

The ADAM10 prodomain is a specific inhibitor of ADAM10 proteolytic activity and inhibits cellular shedding events.

ADAM10 is a disintegrin metalloproteinase that processes amyloid precursor protein and ErbB ligands and is involved in the shedding of many type I and type II single membrane-spanning proteins. Like tumor necrosis factor-alpha-converting enzyme (TACE or ADAM17), ADAM10 is expressed as a zymogen, and removal of the prodomain results in its activation. Here we report that the recombinant mouse ADAM10 prodomain, purified from Escherichia coli, is a potent competitive inhibitor of the human ADAM10 catalytic/disintegrin domain, with a K(i) of 48 nM. Moreover, the mouse ADAM10 prodomain is a selective inhibitor as it only weakly inhibits other ADAM family proteinases in the micromolar range and does not inhibit members of the matrix metalloproteinase family under similar conditions. Mouse prodomains of TACE and ADAM8 do not inhibit their respective enzymes, indicating that ADAM10 inhibition by its prodomain is unique. In cell-based assays we show that the ADAM10 prodomain inhibits betacellulin shedding, demonstrating that it could be of potential use as a therapeutic agent to treat cancer.

Secretion of cytokines in breast cancer cells: the molecular mechanism of procathepsin D proliferative effects.

Procathepsin D (pCD) is a major secreted protein in estrogen receptor-positive (ER+) breast cancer cell lines. Several independent studies have documented pronounced mitogenic effect of secreted pCD on cancer tissue-derived cell lines, including those from breast, lung, and prostate cancer. It has also been shown that the proliferative effect of pCD involves both autocrine and paracrine modes of action. Recent studies have suggested that pCD could act as a key paracrine communicator between cancer and stromal cells. We have shown earlier that the proliferative activity of pCD depends on the activation peptide sequence of pCD. The present study casts light on the mechanism by which pCD influences the proliferation of cancer cells expressing the ER. Results described in the current paper clearly show that pCD initiates secretion of cytokines interleukin-4 (IL-4), IL-8, IL-10, IL-13, macrophage inflammatory protein-1beta and (MIP-1beta) from such tumor cells. Secreted cytokines take part in the proliferation of the cancer cells, as proven by selective inhibition using antibodies. In addition, expression of cytokine receptors on tested cell lines corresponded to the effects of individual cytokines. An analogous pattern was also observed for fibroblasts, which, under physiologic conditions, are the cells in closest contact with the tumor tissue and play a role in tumor growth and invasion. Our observations were further supported by coculture experiments that are in agreement. Although very similar in response to addition of pCD, the invasive ER- cells do not secrete cytokines. Together with previous in vivo results, these data point to pCD as one of key molecules for therapeutic attack in breast cancer.

The molecular mechanism of interaction between sushi peptide and Pseudomonas endotoxin.

Septic shock is caused by Gram-negative bacterial infection. Lipopolysaccharide (LPS) is the bioactive molecule present on the outer membrane of the Gram-negative bacteria. It is generally thought that LPS interacts with sensors on the host cell membrane to activate the intracellular signaling pathway resulting in the overproduction of cytokines such as TNF-alpha. This causes inflammation and ultimately, septic shock. Lipid A is the pharmacophore of the LPS molecule. Thus, developing bio-molecules which are capable of binding LPS at high affinity, especially to the lipid A moiety is an efficient way to neutralize the LPS toxicity. Factor C, a serine protease in the horseshoe crab ameobocytes, is sensitive to trace levels of LPS. We have derived Sushi peptides from the LPS-binding domains of Factor C. Our earlier study showed that the Sushi peptides inhibit LPS-induced septic shock in mice. Here, we demonstrate that the molecular interaction between LPS and Sushi 1 peptide is supported by the hydrophobic interaction between the lipid tail of LPS and Sushi 1 peptide. Furthermore, in the presence of LPS, the peptide transitions from a random structure into an alpha-helical conformation and it disrupts LPS aggregates, hence, neutralizing the LPS toxicity.

Targeting Syk as a treatment for allergic and autoimmune disorders.

Recent advances in our understanding of allergic and autoimmune disorders have begun to translate into novel, effective and safe medicines for these common maladies. Examples include an anti-IgE monoclonal antibody recently approved for severe asthmatics and the TNF-alpha antagonists that have demonstrated their ability to suppress rheumatoid arthritis, Crohn's disease and other chronic inflammatory processes. However, protein therapies are difficult and expensive to develop, manufacture and administer. Clearly, there is also a need for small-molecule inhibitors of novel targets that have safe and effective characteristics. Syk is an intracellular protein tyrosine kinase that was discovered 15 years ago as a key mediator of immunoreceptor signalling in a host of inflammatory cells including B cells, mast cells, macrophages and neutrophils. These immunoreceptors, including Fc receptors and the B-cell receptor, are important for both allergic diseases and antibody-mediated autoimmune diseases and thus pharmacologically interfering with Syk could conceivably treat these disorders. In addition, as Syk is positioned upstream in the cell signalling pathway, therapies targeting Syk may be more advantageous relative to drugs that inhibit a single downstream event. Syk inhibition during an allergic or asthmatic response will block three mast cell functions: the release of preformed mediators such as histamine, the production of lipid mediators such as leukotrienes and prostaglandins and the secretion of cytokines. In contrast, commonly used antihistamines or leukotriene receptor antagonists target only a single mediator of this complex cascade. Despite its expression in platelets and other non-haematopoietic cells, the role of Syk in regulating vascular homeostasis and other housekeeping functions is minimal or masked by redundant Syk-independent pathways. This suggests that targeting Syk would be an optimal approach to effectively treat a multitude of chronic inflammatory diseases without undue toxicity.

Antisense oligonucleotides to Syk kinase: a novel therapeutic approach for respiratory disorders.

The non-receptor protein tyrosine kinase Syk plays a critical role in intracellular signaling in the inflammatory response. Specific inhibition of Syk using aerosolized antisense delivered in liposome complexes can significantly decrease inflammatory responses in the airways in experimental animal models. Thus, it is tempting to examine local application of Syk antisense for the treatment of inflammatory respiratory diseases as asthma. However, evidence that Syk kinase is more widely distributed in different cell types than previously recognized, as well as its potential involvement in cell differentiation, adhesion and proliferation, dictates that the precise cellular targets for antisense therapy in the airways must be determined. Given the critical role of Syk in intracellular signaling in inflammatory responses, Syk antisense oligonucleotides (InKine Pharmaceutical Co Inc) may prove useful as anti-inflammatory therapy in disorders such as asthma.

Modified apoptotic molecule (BID) reduces hepatitis C virus infection in mice with chimeric human livers.

Hepatitis C virus (HCV) encodes a polyprotein consisting of core, envelope (E1, E2, p7), and nonstructural polypeptides (NS2, NS3, NS4A, NS4B, NS5A, NS5B). The serine protease (NS3/NS4A), helicase (NS3), and polymerase (NS5B) constitute valid targets for antiviral therapy. We engineered BH3 interacting domain death agonist (BID), an apoptosis-inducing molecule, to contain a specific cleavage site recognized by the NS3/NS4A protease. Cleavage of the BID precursor molecule by the viral protease activated downstream apoptotic molecules of the mitochondrial pathway and triggered cell death. We extended this concept to cells transfected with an infectious HCV genome, hepatocytes containing HCV replicons, a Sindbis virus model for HCV, and finally HCV-infected mice with chimeric human livers. Infected mice injected with an adenovirus vector expressing modified BID exhibited HCV-dependent apoptosis in the human liver xenograft and considerable declines in serum HCV titers.

Thrombolysis and percutaneous transluminal coronary angioplasty in patients with acute myocardial infarction.

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality in the developed countries. Thrombotic occlusion of a coronary artery has been shown to cause acute myocardial infarction in over 90% of the cases. Early and complete restoration of bloodflow in the infarct-related coronary artery is the principal mechanism by which reperfusion therapy improves outcomes in patients with acute myocardial infarction. Thrombolytic therapy has been shown to reduce mortality when given early after symptom onset. However, even the most effective, approved thrombolytic regimens achieve normal (so-called TIMI 3) flow in the infarct vessel at 60-90 minutes only in about half of the patients and reocclusion occurs in 5-10%. Bleeding events, especially intracranial bleedings, observed in up to 1% of the patients, are the most severe complication of thrombolysis. Primary percutaneous transluminal coronary angioplasty (PTCA) is associated with somewhat higher patency rates and significantly fewer strokes than thrombolysis, but confers a reocclusion rate of about 5-10% and it is not universally available. While smaller randomized studies suggested a significant advantage of PTCA over thrombolysis, these results could not be confirmed in the larger GUSTO IIb angioplasty study in over 1000 patients and in non-randomized comparisons in large registries. Therefore, a general mortality advantage of PTCA over thrombolysis could not be demonstrated. Primary PTCA should be preferred in patients with contraindications against thrombolysis, patients with a high risk for intracranial bleedings (age > 75 and high blood pressure on admission) and hemodynamically unstable patients. There are several approaches to improve outcome of patients with acute myocardial infarction: new fibrinolytic agents may improve early infarct related patency, single bolus administration of thrombolytics may reduce time-to-treatment, stent implantation may improve direct PTCA, enhanced thrombin and platelet inhibition may facilitate both, thrombolysis and primary PTCA, enhance reperfusion on the cellular level and reduce reocclusions and ultimately improve prognosis of patients with acute myocardial infarction.

Prourokinase versus urokinase for recanalization of peripheral occlusions, safety and efficacy: the PURPOSE trial.

BACKGROUND: The intraarterial administration of thrombolytic agents is associated with clinical benefits in patients with acute peripheral arterial occlusion, and urokinase has been the agent that has become the standard of care in the United States. Recombinant prourokinase (r-ProUK) offers potential as a novel agent with improved fibrin specificity and, as such, may offer advantages as an attractive alternative to urokinase. METHODS: A randomized, double-blind, parallel, phase II, prospective multicenter trial was undertaken to compare three doses of intra-arterial, catheter-directed r-ProUK (2 mg, 4 mg, or 8 mg/hr for 8 hrs, then 0.5 mg/hr) versus one dose of tissue-culture urokinase (4,000 IU/min for 4 hrs, then 2,000 IU/min) for the treatment of acute lower extremity arterial occlusion of 14 days' duration or less (n = 241). The primary endpoint was complete (>95%) lysis of the occluding thrombus after 8 hours of infusion. RESULTS: Increased clot lysis at 8 hours, decreased fibrinogen concentration, and an increased rate of hemorrhagic events were observed as the r-ProUK dose was increased from 2 mg/hr to 8 mg/hr. Similarly, a decreased duration of study drug infusion was seen, decreasing from 16.7 +/- 0.90 hours in the 2 mg/hr group to 12.7 +/- 0.97 hours in the 8 mg/hr group. The results for the urokinase group decreased to a level between those observed for the 2 mg and 8 mg r-ProUK group with respect to clot lysis at 8 hours, fibrinogen decrement, and bleeding complications, approximating those observed in the 4 mg/hr r-ProUK group. These results were achieved with a relatively low rate of major bleeding events and no episodes of intracranial hemorrhage. CONCLUSIONS: The 8 mg/hr dose of r-ProUK was associated with an increased rate of thrombolysis relative to the other treatment groups, associated with a slightly increased frequency of bleeding complications and decrements in fibrinogen concentration. Conversely, the 2 mg/hr r-ProUK dose was associated with a slightly slower rate of thrombolysis, but bleeding complications and fibrinogenolysis were diminished. r-ProUK is a novel thrombolytic agent with a dose-related safety and efficacy profile. As such, it offers potential as a useful tool in the treatment of peripheral vascular occlusion.

Immobilized proteinases in the treatment of diffuse purulent peritonitis.

In vitro experiments on fibrin films using purulent exudate from the abdominal cavity of rats with experimental peritonitis demonstrate the fibrinolytic effect of bacterial proteinases immobilized on a polymeric matrix. The application of Imozimaza in the complex treatment of experimental peritonitis by the way of intraperitoneal lavage resulted in reliable lowering of mortality, due to the lysis of fibrinopurulent abdominal contents and better contact between antibacterial agents and peritonitis pathogens. In the clinic, prolonged abdominal proteolysis was applied to 44 patients with postoperative diffuse purulent peritonitis of >24 h duration. Under the conditions of programmable relaparotomy, intraperitoneal Imozimaza infusion led (as in in vitro tests) to the lysis of fibrinopurulent masses, which contained micro-organisms of an order higher than exudate. It was accompanied by increase in the drainage efficacy, absence of fragmentation of abdominal contents and absence of secondary abscesses. The use of Imozimaza on the background of complex antibacterial treatment and combined homeostatic therapy resulted in lowering of mortality from 65.8% to 27.3%. Complications and contra-indications for Imozimaza use in diffuse purulent peritonitis were not registered.

PROACT: a phase II randomized trial of recombinant pro-urokinase by direct arterial delivery in acute middle cerebral artery stroke. PROACT Investigators. Prolyse in Acute Cerebral Thromboembolism.

BACKGROUND AND PURPOSE: To test the safety and recanalization efficacy of intra-arterial local delivery of plasminogen activators in acute ischemic stroke, a randomized trial of recombinant pro-urokinase (rpro-UK) versus placebo was undertaken in patients with angiographically documented proximal middle cerebral artery occlusion. METHODS: After exclusion of intracranial hemorrhage by CT scan, patients with abrupt onset of symptoms of focal ischemia likely to receive treatment within 6 hours who satisfied all clinical eligibility criteria underwent carotid angiography. Patients displaying Thrombolysis in Acute Myocardial Infarction grade 0 or 1 occlusion of the M1 or M2 middle cerebral artery were randomized 2:1 to receive rpro-UK (6 mg) or placebo over 120 minutes into the proximal thrombus face. All patients received intravenous heparin. Recanalization efficacy was assessed at the end of the 2-hour infusion, and intracerebral hemorrhage causing neurological deterioration was assessed at 24 hours. RESULTS: Of 105 patients who underwent angiography, 59 were excluded from randomization. Among the 46 patients randomized, 40 were treated with rpro-UK (n=26) or placebo (n=14) a median of 5.5 hours from symptom onset. Recanalization was significantly associated with rpro-UK (2P=.017). Hemorrhagic transformation causing neurological deterioration within 24 hours of treatment occurred in 15.4% of the rpro-UK-treated patients and 7.1% of the placebo-treated patients (2P=.64). Both recanalization and hemorrhage frequencies were influenced by heparin dose. CONCLUSIONS: Intra-arterial local rpro-UK infusion was associated with superior recanalization in acute thrombotic/ thromboembolic stroke compared with placebo. In this regimen, heparin dose influenced hemorrhage frequency and recanalization. Although symptomatic hemorrhage remains a concern, this study suggests that recanalization is enhanced with rpro-UK and heparin.

Hyperacute stroke therapy with tissue plasminogen activator.

The past year has seen tremendous progress in developing new therapies aimed at reversing the effects of acute stroke. Thrombolytic therapy with various agents has been extensively studied in stroke patients for the past 7 years. Tissue plasminogen activator (t-PA) received formal US Food and Drug Administration approval in June 1996 for use in patients within 3 hours of onset of an ischemic stroke. Treatment with t-PA improves neurologic outcome and functional disability to such a degree that, for every 100 stroke patients treated with t-PA, an additional 11-13 will be normal or nearly normal 3 months after their stroke. The downside of t-PA therapy is a 6% rate of symptomatic intracerebral hemorrhage (ICH) and a 3% rate of fatal ICH. Studies are under way to determine whether t-PA can be administered with an acceptable margin of safety within 5 hours of stroke, to evaluate the therapeutic benefits of intraarterial pro-urokinase, and to assess the use of magnetic resonance spectroscopy to identify which patients are most likely to benefit from thrombolysis. Combination thrombolytic-neuroprotectant therapy is also being studied. In theory, patients could be given an initial dose of a neuroprotectant by paramedics and receive thrombolytic therapy in the hospital. We are now entering an era of proactive, not reactive, stroke therapies. These treatments may reverse some or all acute stroke symptoms and improve functional outcomes.

[Fibrinolytic agents--who benefits when?]. / Fibrinolytika--Wer profitiert wann?

Thrombolytic therapy mimics and enhances physiological fibrinolysis. The following substances are presently available for clinical use: the nonphysiological thrombolytics streptokinase, the APSAC (acylated plasminogen-streptokinase activator complex), the physiological plasminogen activators urokinase and tissue plasminogen activator (t-PA). Whereas the first three systematically activate the fibrinolytic system, t-PA possesses relative fibrin selectivity. The fibrin-selective active pro-urokinase has not yet been officially approved for the treatment of thromboembolic diseases, but it is being clinically tested. Fibrinolytic therapy has an established place in the management of acute myocardial infarction and of massive pulmonary embolism. When an acute deep venous thrombosis is diagnosed with a proximal extension into the popliteal vein, thrombolytic therapy is clearly superior to heparin. The lysis has proven to be an effective form of treatment of peripheral occlusive arterial disease. Local thrombolytic therapy is an option for acute and chronic femoro-popliteal occlusions involving the trifurcation into the calf arteries and for embolic occlusions of the same segment in patients with contraindications to surgical therapy. First study results of thrombolytic therapy of stroke are promising.