Pathophysiology and management of subretinal hemorrhage

Subretinal hemorrhage can arise from the retinal and/or choroidal circulation. Significant subretinal hemorrhage occurs in several conditions, but most commonly is associated with age-related macular degeneration, presumed ocular histoplasmosis, high myopia, retinal arterial macroaneurysm, and trauma. Released toxins, outer retinal shear forces, and a diffusion barrier created by subretinal hemorrhage all contribute to photoreceptor damage and visual loss. The use of tissue plasminogen activator and improvements in surgical instrumentation have facilitated surgical drainage and have made it a useful option in the management of selected cases. Mechanisms of subretinal hemorrhage formation, underlying etiologies, diagnostic evaluation, and the histopathology of damage are summarized. Published surgical series are reviewed and surgical advances are summarized. The value of surgically removing subretinal hemorrhages to improve visual outcome remains unestablished, because definitive studies have not been performed. Guidelines for selecting candidates for surgical intervention are proposed.     

Nursing care of acute stroke patients after receiving rt-PA therapy. The NINDS rt-PA Stroke Study Group

Treatment with tissue plasminogen activator (rt-PA) for acute stroke requires intensive care of the patient. The risk of thrombolytic therapy and the need for rapid interventions make it clear that the nursing role during this time is crucial. Nurses should be familiar with safe dosage and administration of rt-PA for stroke, which is clearly different than administration of rt-PA for myocardial infarction. Furthermore, thrombolytic stroke treatment must be accompanied by intensive neurological monitoring to observe for complications. Intracerebral hemorrhage is usually accompanied by an acute change in neurological status and vital sign instability. Intensive monitoring of neurologic condition, vital signs, cardiac status and other standard critical care practices must be initiated immediately to optimize patient outcome.     

Pitfalls in the economic evaluation of thrombolysis in myocardial infarction. The impact of national differences in the cost of thrombolytics and of differences in the efficacy across patient subgroups

BACKGROUND: The economic evaluation of the results of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Artery (GUSTO) trial found that recombinant tissue plasminogen activator is more cost-effective than streptokinase for the treatment of acute myocardial infarction. AIM: We evaluated the impact on a cost effectiveness analysis, of the differences in the cost of thrombolytics among countries and of differences in efficacy across patient subgroups. METHODS: We considered the crude costs of streptokinase and recombinant tissue plasminogen activator in Germany, Italy, the United Kingdom, and the United States of America, and the 30-day mortality found in the GUSTO trial. We calculated the incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator. We also calculated the incremental costs for each life saved for two protocols implying a selective use of streptokinase and recombinant tissue plasminogen activator (age-selective protocol: recombinant tissue plasminogen activator in patients < or = 75 years, streptokinase in older patients; site-selective protocol: recombinant tissue plasminogen activator in anterior acute myocardial infarction, streptokinase in non-anterior acute myocardial infarction). RESULTS: The incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator in all GUSTO patients vary greatly among countries: the incremental costs for each life saved are 31%, 45%, and 97% higher in Germany, Italy, and the United States of America compared to the United Kingdom. The use of a site-selective protocol implies a halved cost-effectiveness ratio compared to the use of recombinant tissue plasminogen activator in all cases of acute myocardial infarction. CONCLUSIONS: (1) The cost-efficacy of recombinant tissue plasminogen activator vs streptokinase in acute myocardial infarction varies greatly among countries due to differences in the cost of drugs. (2) A selective use of thrombolytics for some sites of infarction is more cost-effective than the exclusive use of recombinant tissue plasminogen activator.     

Submacular hemorrhage removal

PURPOSE: To determine whether pars plana vitrectomy combined with tissue plasminogen activator for evacuation of submacular hemorrhage results in improved visual acuity. METHODS: Retrospective review of 18 patients who received a subretinal injection of tissue plasminogen activator during a pars plana vitrectomy to evacuate dense submacular hemorrhages. RESULTS: Diagnoses included age-related macular degeneration (16 patients), ruptured macroaneurysm (1 patient), and penetrating ocular trauma (1 patient). Preoperative visual acuity ranged from 20/200 to counting fingers (median visual acuity, counting fingers). Follow-up ranged from 10 to 104 weeks (median, 33 weeks). Best postoperative visual acuity ranged from 20/30 to counting fingers (median, 20/300). Best postoperative visual acuity improved two or more lines in 11 (61%) of 18 eyes, remained unchanged in 4 (22%) of 18 eyes, and decreased two or more lines in 3 (17%) of 18 eyes (P = 0.10, Wilcoxon sign-rank test). Final visual acuity ranged from 20/40 to light perception (median, counting fingers). Final visual acuity improved two or more lines in 5 (28%) of 18 eyes, remained unchanged in 6 (33%) of 18 eyes, and decreased two or more lines in 7 (39%) of 18 eyes (P = 0.53, Wilcoxon sign-rank test). CONCLUSIONS: Pars plana vitrectomy to evacuate massive subretinal hemorrhage can improve visual acuity, but final visual acuity is limited by the underlying disease.     

Biosynthesis of riboflavin: an unusual riboflavin synthase of Methanobacterium thermoautotrophicum

BACKGROUND: The aim of this study was to prospectively test whether the risk of bleeding complications in 212 consecutive outpatients treated with oral anticoagulants could be predicted by levels of endothelium-derived hemostatic variables. METHODS AND RESULTS: All bleeding complications were recorded during 5 years of follow-up; serious bleeding was defined as intracranial bleeding or hemorrhage causing death or necessitating hospitalization. The relationships of bleeding complications and plasma concentrations of tissue plasminogen activator, von Willebrand factor, and thrombomodulin, plasminogen activator inhibitor activity, and other possible risk factors were studied. Twenty-two patients suffered from bleeding complications during anticoagulant treatment; in 14 patients, these were serious. We found that the numbers both of serious hemorrhages and of total hemorrhages were significantly associated with increased levels of thrombomodulin. The number of bleeding episodes increased exponentially through quartiles one to four of the thrombomodulin distribution. CONCLUSIONS: Thrombomodulin concentrations in plasma are related to the risk of hemorrhage in patients treated with oral anticoagulants.     

Use of allografts in knee reconstruction: II. Surgical considerations

This paper aims to review current literature on the treatment of acute intraventricular hemorrhage in adults with intraventricular infusion of fibrinolytic agents. A literature search on the topics of "intraventricular hemorrhage" or "intracerebral hemorrhage" with "thrombolytic therapy", "fibrinolytic therapy", "urokinase", "streptokinase", "tissue plasminogen activator" or "tPA" covering the years 1966-1997 was carried out electronically. This was supplemented by searching the reference lists of the identified articles. Articles regarding exclusively intracerebral hemorrhage or hematoma, neonatal intraventricular hemorrhage, non-therapeutic issues, and laboratory research were excluded. The included articles are summarized in evidence and evaluation tables. Six articles evaluating the treatment of intraventricular hemorrhage in adults with intraventricular fibrinolytic agents were identified. One reports a small randomized clinical trial including 16 patients and appears to show a statistically insignificant preference for urokinase treatment. Five other reports present case series for which a total of 58 patients were exposed to either streptokinase, urokinase, or recombinant tissue plasminogen activator (rt-PA) and suggest good outcome. Two of them were with non-randomized retrospective or prospective controls, and three have no controls. Despite important limitations, all reports suggest that blood is more rapidly cleared from the ventricles and outcome is better when administering a fibrinolytic agent intraventricularly. While the experience presented in these papers suggests that intraventricular administration of fibrinolytic agents may be associated with fewer complications, more rapid clearing of blood from the ventricles, less late hydrocephalus, and better long-term outcome than is seen in patients treated with ventricular drainage alone, it is insufficient to recommend such treatment as a matter of policy. Substantial methodologic flaws render these findings suggestive at best. If the suggestive findings of these studies were confirmed in well-designed randomized clinical trials, an important impact on clinical practice could be expected.     

Traumatic intraventricular hemorrhage treated with intraventricular recombinant-tissue plasminogen activator: technical case report

OBJECTIVE AND IMPORTANCE: Traumatic intraventricular hemorrhage (IVH) can result in association with acute obstructive hydrocephalus, repetitive malfunction of external ventricular drains (EVDs), and uncontrollable increased intracranial pressure. We report a case showing the safe and effective use of intraventricular recombinant-tissue plasminogen activator in a child with severe brain injury and acute hydrocephalus from IVH. CLINICAL PRESENTATION: A 15-year-old male patient presented to us after a motor vehicle accident with bilateral extensor posturing, intracerebral and IVH, and acute obstructive hydrocephalus. INTERVENTION: A right EVD was placed and functioned only transiently. A left EVD was placed and functioned only transiently. Because of the inability to maintain ventricular drainage, rising intracranial pressure, and worsening clinical status, 5 mg of recombinant-tissue plasminogen activator was injected through each EVD. Excellent EVD function was obtained quickly, with control of intracranial pressure and improvement in clinical status and without hemorrhagic complication. CONCLUSION: With obstructive hydrocephalus secondary to acute traumatic IVH that cannot be controlled with EVD because of recurrent obstruction from intraventricular blood, intraventricular recombinant-tissue plasminogen activator can be effective and safe, despite preexisting multiple hemorrhagic intracranial injuries.     

Decreased fibrinolytic activity in porcine-to-primate cardiac xenotransplantation

BACKGROUND: One major barrier to successful xenotransplantation is acute vascular rejection, a process pathologically characterized by microvascular thrombosis and diffuse fibrin deposition in transplant blood vessels. This pathologic picture may result from a disturbance in the coagulant or fibrinolytic pathways that regulate normal vascular patency. This study evaluated the regulation of fibrinolytic activity defined by tissue plasminogen activator and plasminogen activator inhibitor-1 as it may exist in the setting of acute vascular rejection. MATERIALS AND METHODS, RESULTS: Serial biopsies from cardiac xenotransplants evaluated by immunofluorescence microscopy demonstrated progressive decreases in tissue plasminogen activator and increases in plasminogen activator inhibitor-1. In vitro studies measuring fibrinolytic activity of cell culture medium from porcine aortic endothelial cells stimulated with human serum or autologous porcine serum revealed that human serum triggered as much as 93% increase in antifibrinolytic activity. CONCLUSIONS: These findings demonstrate that porcine vascular endothelial cells change toward an antifibrinolytic state following stimulation with human xenoreactive antibodies and complement. The shift is at least partly explained by an increased ratio of plasminogen activator inhibitor-1 to tissue plasminogen activator, and is at least in part mediated by the activation of complement. This increased antifibrinolytic activity may contribute to the thrombotic diathesis seen in acute vascular rejection in pig-to-primate xenografts.     

Expression of the plasminogen activation system in kidney cancer correlates with its aggressive phenotype

Malignant tumors contrast with benign ones in their ability to invade adjacent tissue and to metastasize. The urokinase plasminogen activator is a proteolytic enzyme that can facilitate these processes. In many carcinomas, the concentration of the urokinase plasminogen activator system is high. The high expression of these enzymes is related to tumor grade. In this study, we have investigated whether secretion of the urokinase plasminogen activator, urokinase plasminogen activator receptor, and plasminogen activator inhibitor 1 in normal kidney tissue and kidney cancer tissue follows this pattern. We have found that urokinase plasminogen activator, urokinase plasminogen activator receptor, and plasminogen activator inhibitor 1 were expressed in higher levels in kidney cancers (squamous cell carcinoma and renal cell carcinoma) than in normal kidney tissue and that these differences were statistically significant (P < or = 0.05). In renal cell carcinomas, we have observed differences between normal kidney tissue and renal cell carcinomas in males and Caucasians but not in females and African Americans (P < or = 0.05). Expression of the urokinase plasminogen activator system was also higher in grade III tumors when compared with lower-grade tumors or normal tissue.     

Increased fibrinogen levels and acquired hypofibrinolysis in young adults with ischemic stroke

BACKGROUND AND PURPOSE: Elevated fibrinogen levels and abnormalities in the fibrinolytic system are related to the occurrence of cardiovascular events. However, the role of these factors in the evolution of cerebrovascular disease has received less attention, in particular in young stroke patients. The aim of this study was to evaluate possible abnormalities in plasma fibrinogen levels and the state of the fibrinolytic system in young adults with a first-ever ischemic stroke. METHODS: This study is based on 102 consecutive patients aged 18 to 44 years admitted between January 1991 and May 1996 as a result of a first ischemic stroke. Forty-one healthy controls were recruited. Evaluations of anthropometric/metabolic variables, plasma fibrinogen levels, and the fibrinolytic system were undertaken >/=3 months (mean, 5.4+/-2.0 months) after admission. RESULTS: Patients had lower tissue plasminogen activator activity and increased plasminogen activator inhibitor type 1 activity at baseline, as well as increased tissue plasminogen activator mass concentration both at baseline and after a venous occlusion test. Overall, there were no significant differences between the main etiologic subgroups regarding plasma fibrinogen levels and fibrinolytic variables. Baseline fibrinolytic variables were strongly correlated with body mass index, serum triglycerides, and cholesterol levels. After adjustments in multivariate models, fibrinogen levels and tissue plasminogen activator mass concentration both at baseline and after venous occlusion test remained significantly increased in patients. Logistic multiple regression analyses indicated that plasma fibrinogen was a strong predictor of ischemic stroke (odds ratio, 11.25; 95% CI, 3.27 to 38. 69). CONCLUSIONS: Increased fibrinogen levels and tissue plasminogen activator mass concentration are independently associated with ischemic stroke in young adults. Metabolic perturbations are closely interrelated with aberrations in tissue plasminogen activator and plasminogen activator inhibitor type 1 activity in these patients, findings consistent with an acquired hypofibrinolysis.     

Pharmacokinetics of once-daily amikacin dosing in patients with cystic fibrosis

PURPOSE: To report the injection of tissue plasminogen activator into a retinal vein to treat central retinal vein occlusion. METHODS: An 81-year-old woman with visual loss of the right eye secondary to central retinal vein occlusion developed central retinal vein occlusion and visual loss in her left eye. Treatment of her left eye with topical ocular hypotensive medications, pentoxifylline, and laser chorioretinal anastomosis was without benefit. Thereafter, she underwent vitreoretinal surgery, including tissue plasminogen activator injection into a branch retinal vein of her left eye. RESULTS: The patient reported subjective improvement in the vision of her left eye. Ophthalmoscopic and fluorescein angiographic improvement were also noted. CONCLUSION: The feasibility of cannulating a retinal vein for treatment has been demonstrated.     

Differential effects of tissue plasminogen activator and streptokinase on infarct size and on rate of enzyme release: influence of early infarct related artery patency. The GUSTO Enzyme Substudy

BACKGROUND: The recent international GUSTO trial of 41,021 patients with acute myocardial infarction demonstrated improved 90-min infarct related artery patency as well as reduced mortality in patients treated with an accelerated regimen of tissue plasminogen activator, compared to patients treated with streptokinase. A regimen combining tissue plasminogen activator and streptokinase yielded intermediate results. The present study investigated the effects of treatment on infarct size and enzyme release kinetics in a subgroup of these patients. METHODS: A total of 553 patients from 15 hospitals were enrolled in the study. Four thrombolytic strategies were compared: streptokinase with subcutaneous heparin, streptokinase with intravenous (i.v.) heparin, tissue plasminogen activator with i.v. heparin, and streptokinase plus tissue plasminogen activator with i.v. heparin. The activity of alpha-hydroxybutyrate dehydrogenase (HBDH) in plasma was centrally analysed and infarct size was defined as cumulative HBDH release per litre of plasma within 72 h of the first symptoms (Q(72)). Patency of the infarct-related vessel was determined by angiography in 159 patients, 90 min after treatment. RESULTS: Infarct size was 3.72 g-eq.1(-1) in patients with adequate coronary perfusion (TIMI-3) at the 90 min angiogram and larger in patients with TIMI-2 (4.35 g-eq.1(-1) or TIMI 0-1 (5.07 g-eq.1(-1) flow (P = 0.024). In this subset of the GUSTO angiographic study, early coronary patency rates (TIMI 2 + 3) were similar in the two streptokinase groups (53 and 46%). Higher, but similar, patency rates were observed in the tissue plasminogen activator and combination therapy groups (87 and 90%). Median infarct size for the four treatment groups, expressed in gram-equivalents (g-eq) of myocardium, was 4.4, 4.5, 3.9 and 3.9 g-eq per litre of plasma (P = 0.04 for streptokinase vs tissue plasminogen activator). Six hours after the first symptoms, respectively 5.3, 6.6, 14.0 and 13.6% of total HBDH release was complete (P < 0.0001 for streptokinase vs tissue plasminogen activator). CONCLUSIONS: Rapid and complete coronary reperfusion salvages myocardial tissue, resulting in limitation of infarct size and accelerated release of proteins from the myocardium. Treatment with tissue plasminogen activator, resulting in earlier reperfusion was more effective in reducing infarct size than the streptokinase regimens, which contributes to the differences in survival between treatment groups in the GUSTO trial.     

Fibrinolytic components in fetal membranes and amniotic fluid

OBJECTIVE: We evaluated fibrinolytic components in plasma and amniotic fluid of pregnant women and in postpartum fetal membranes. STUDY DESIGN: Fibrinolytic parameters in amniotic fluid and plasma were measured by means of enzyme-linked immunosorbent assays. Fetal membranes collected after spontaneous labor at term were analyzed by immunohistochemical methods with immunospecific antibodies against fibrinolytic components. RESULTS: Amniotic fluid contained high plasminogen activator inhibitor-1 concentrations but had low activity. Strong staining for plasminogen activator inhibitor-1 and vitronectin was observed in chorionic trophoblasts and moderate staining in decidual connective tissue. Strong staining for plasminogen activator inhibitor-2 was seen in decidual cells. Although prominent staining of plasminogen activators and plasminogen were observed in the amniotic epithelium, virtually no plasminogen activator inhibitor-1, plasminogen activator inhibitor-2, or alpha 2-plasmin inhibitor staining was detected. CONCLUSION: The delicate balance of fibrinolytic activators and inhibitors in fetal membranes and amniotic fluid may contribute to the triggering of membrane rupture at term.     

Retinoids and fibrinolysis

Vitamin A and its analogues have been reported to increase the release of tissue plasminogen activator in vitro. The aim of the present study was to reevaluate these findings and to investigate whether retinoids in doses used in dermatological therapy could enhance the release of endothelial fibrinolytic factors. Our results showed that endothelial cells incubated in vitro with retinoic acid increased the release of tissue plasminogen activator to the supernatant without concomitant secretion of plasminogen activator inhibitor-1. In patients treated with isotretinoin or etretinate these findings were confirmed, showing enhanced baseline tissue plasminogen activator concentrations in plasma in association with unchanged levels of plasminogen activator inhibitor-1 and von Willebrand factor. These findings are consistent with chronically augmented tissue plasminogen activator secretion without evidence of endothelial cell damage and may be of importance for the interpretation of the safety of lon-term therapy with regard to retinoid-induced hyperlipemia and the development of cardiovascular disease.     

Coagulative and fibrinolytic activation in cerebrospinal fluid and plasma after subarachnoid hemorrhage

OBJECTIVE: Intrathecal fibrinolytic therapy has been used as one of the anticerebral vasospasm (VS) preventative therapies in patients with subarachnoid hemorrhage (SAH). However, the changes in coagulation and fibrinolysis in the blood and cerebrospinal fluid (CSF) after SAH remain unknown. METHODS: Fifty patients with SAH caused by ruptured cerebral aneurysms were studied postoperatively to detect the serial changes of the thrombin-antithrombin III complex, active plasminogen activator inhibitor (PAI)-1, and tissue plasminogen activator (tPA)-PAI complex (tPA-PAI) activities in the plasma and CSF collected from cisternal drainage catheters. RESULTS: The CSF levels of all parameters and plasma PAI-1 levels were significantly higher in patients with severe SAH than in those with mild SAH. There was no relationship between the CSF and plasma levels of these parameters (except the CSF levels of tPA-PAI) and the initial neurological statuses. The CSF PAI-1 levels increased to greater than 20 ng/ml near the time of the occurrence of cerebral VS, whereas they remained below 20 ng/ml in patients without VS. The CSF tPA-PAI levels showed the highest peak near the time of VS remission. The CSF PAI-1 and tPA-PAI levels were significantly lower in patients with good outcomes than in those with poor outcomes. CONCLUSION: Both the coagulative and fibrinolytic systems were activated in the CSF and plasma after SAH in correlating to the amount of SAH clot. The intrathecal administration of fibrinolytic agents should be started early after surgery, before CSF PAI-1 levels increase, for patients with severe SAH. Patients with CSF PAI-1 levels greater than 20 ng/ml experienced high incidence of VS and poor outcomes.     

Coagulation-fibrinolysis system in poststroke patients receiving antiplatelet medication

BACKGROUND AND PURPOSE: We studied the activities of the coagulation-fibrinolysis system in the chronic stage of poststroke patients and the effect of antiplatelet medication on the system. METHODS: We determined fibrinogen, antithrombin III, thrombin-antithrombin III complex, tissue plasminogen activator antigen, plasminogen activator inhibitor-1, plasmin-alpha 2 plasmin inhibitor complex, and D-dimer in plasma from 153 poststroke patients in the chronic phase (ie, 33 patients not receiving antiplatelet medication, 78 patients receiving 200 mg/d ticlopidine, and 42 patients receiving 40 mg/d aspirin), and compared the results in control subjects and among the treatment groups. RESULTS: The concentrations of fibrinogen, thrombin-antithrombin III complex, antithrombin III, plasmin-alpha 2 plasmin inhibitor complex, and tissue plasminogen activator were slightly but significantly increased in all treatment groups compared with control subjects (P < .01) but did not differ among the treatment groups. The plasminogen activator inhibitor-1 levels were significantly elevated in patients not receiving antiplatelet medication compared with control subjects (P < .01), whereas they were in the normal range and significantly lower in patients receiving ticlopidine or aspirin than in patients not receiving antiplatelet medication (P < .01). The plasminogen activator inhibitor-1 levels were significantly lower in patients whose platelet aggregation was inhibited by antiplatelet medication than in patients with uninhibited platelet aggregability (P < .05). CONCLUSIONS: These findings suggest that coagulation-fibrinolysis markers are mildly increased in poststroke patients in the chronic phase and that antiplatelet medication is effective in reducing the elevated plasminogen activator inhibitor-1 levels.     

Tissue plasminogen activator mRNA expression in granule neurons coincides with their migration in the developing cerebellum

Tissue plasminogen activator activity in the developing cerebellum, as quantified by zymography of cerebellar homogenates from embryonic day (E) 17 to adult mice, shows a peak of activity at postnatal day (P) 7, followed by a steady 75% decrease into adulthood. Northern blot analysis reveals a similar pattern for tissue plasminogen activator mRNA levels, which are low at E17 but increase dramatically, reaching their highest levels of specific mRNA/micrograms RNA in P1-P7 mice and declining about threefold in the adult mouse. In situ hybridization of whole mouse brain sections with a tissue plasminogen activator antisense cRNA probe shows pronounce reactivity in the cerebellum. Although some binding is associated with the cerebellar meninges, the external granule layer is devoid of tissue plasminogen activator mRNA at all ages. However, highly labeled elongated cells, which also bind antibody to neuronal nuclear antigen and are adjacent to Bergmann glial fibers (i.e., migrating granule neurons), are readily visible throughout the molecular and Purkinje layers at P7 and P14. In the adult mouse cerebellum, tissue plasminogen activator mRNA labeling is restricted to cells in the Purkinje/internal granule layers. Thus, tissue plasminogen activator gene expression is induced as granule neurons leave the external granule layer and begin their inward migration.     

The cleavage of pro-urokinase type plasminogen activator by stromelysin-1

Membrane binding of urokinase type plasminogen activator (u-PA) is thought to play a pivotal role in connective tissue remodeling and invasive processes. We compare the ability of different matrix-metalloproteinases involved in connective tissue turnover to cleave pro-urokinase type plasminogen activator between the catalytic domain and the receptor binding part to investigate a potential role for matrix-metalloproteinases in the regulation of membrane-associated proteolytic activity. We employed several forms of human stromelysin-1 (full length, C-truncated, and recombinant catalytic domain), rabbit C-truncated stromelysin-1, the human gelatinases A and B and the human catalytic domain of neutrophil collagenase. The gelatinases and the collagenase did not separate the receptor binding domain of pro-urokinase type plasminogen activator from the catalytic domain, whereas all stromelysin-1 forms cleaved the glutamic acid 143-leucine 144 bond of pro-urokinase type plasminogen activator. This reaction could be inhibited by specific inhibitors of matrix metalloproteinases and was not affected by inhibitors of serine proteinases. The M(r) 31000 cleavage product with leucine 144 as N-terminus displayed no proteolytic activity towards the pro-urokinase type plasminogen activator substrate pyroGlu-Gly-Arg-pNA-HCI (S2444), but it could be activated by an additional treatment with plasmin. Comparison between full length stromelysin-1 and its C-truncated forms, showed that both exhibited the same cleavage properties towards pro-urokinase type plasminogen activator. Thus, the cleavage of pro-urokinase type plasminogen activator by stromelysin-1 is not influenced by the presence or absence of the C-terminal domain. The recombinant catalytic domain of MMP-3 generated pro-urokinase type plasminogen activator, whereas incubation of pro-urokinase type plasminogen activator with the native forms of human or rabbit stromelysin-1 led to a moderate activation of pro-uPA due to an additional cleavage that is catalyzed by a serine proteinase.     

Plasminogen activation in synovial tissues: differences between normal, osteoarthritis, and rheumatoid arthritis joints

OBJECTIVE: To analyse the functional activity of the plasminogen activators urokinase (uPA) and tissue type plasminogen activator (tPA) in human synovial membrane, and to compare the pattern of expression between normal, osteoarthritic, and rheumatoid synovium. The molecular mechanisms underlying differences in PA activities between normal and pathological synovial tissues have been further examined. METHODS: Synovial membranes from seven normal (N) subjects, 14 osteoarthritis (OA), and 10 rheumatoid arthritis (RA) patients were analysed for plasminogen activator activity by conventional zymography and in situ zymography on tissue sections. The tissue distribution of uPA, tPA, uPA receptor (uPAR), and plasminogen activator inhibitor type-1 (PAI-1) was studied by immunohistochemistry. uPA, tPA, uPAR, and PAI-1 mRNA values and mRNA distribution were assessed by northern blot and in situ hybridisations respectively. RESULTS: All normal and most OA synovial tissues expressed predominantly tPA catalysed proteolytic activity mainly associated to the synovial vasculature. In some OA, tPA activity was expressed together with variable amounts of uPA mediated activity. By contrast, most RA synovial tissues exhibited considerably increased uPA activity over the proliferative lining areas, while tPA activity was reduced when compared with N and OA synovial tissues. This increase in uPA activity was associated with increased levels of uPA antigen and its corresponding mRNA, which were localised over the synovial proliferative lining areas. In addition, in RA tissues, expression of the specific uPA receptor (uPAR) and of the plasminogen activator inhibitor-type 1