Release Of Plasminogen Activator Research Articles

Pathophysiological Response to Trauma-Induced Coagulopathy: A Comprehensive Review.

Hypercoagulability can occur after severe tissue injury, that is likely related to tissue factor exposure and impaired endothelial release of tissue plasminogen activator (tPA). In contrast, when shock and hypoperfusion occur, activation of the protein C pathway and endothelial tPA release induce a shift from a procoagulant to a hypocoagulable and hyperfibrinolytic state with a high risk of bleeding. Both thrombotic and bleeding phenotypes are associated with increased mortality and are influenced by the extent and severity of tissue injury and degree of hemorrhagic shock. Response to trauma is a complex, dynamic process in which risk can shift from bleeding to thrombosis depending on the injury pattern, hemostatic treatment, individual responses, genetic predisposition, and comorbidities. Based on this body of knowledge, we will review and consider future directions for the management of severely injured trauma patients.

Acute vascular effects of vascular endothelial growth factor inhibition in the forearm arterial circulation.

Objective:Although vascular endothelial growth factor inhibition (VEGFi) represents a major therapeutic advance in oncology, it is associated with hypertension and adverse vascular thrombotic events. Our objective was to determine whether VEGFi caused direct vascular dysfunction through increased endothelin-1 (ET-1) activity or impaired endothelial vasomotor or fibrinolytic function.Methods:Using forearm venous occlusion plethysmography, we measured forearm blood flow during intra-arterial infusions of bevacizumab (36–144 μg/dl forearm volume per minute) administered for 15–60 min in healthy volunteers (n = 6–8). On two separate occasions in 10 healthy volunteers, we further measured forearm blood flow and tissue plasminogen activator (t-PA) release during intra-arterial bradykinin infusion (100 and 1000 pmol/min) in the presence and absence of bevacizumab (144 μg/dl forearm volume per minute), and the presence and absence of endothelin A receptor antagonism with BQ-123 (10 nmol/min). Plasma t-PA and plasminogen activator inhibitor-1 (PAI-1) concentrations were measured at baseline and with each dose of bradykinin.Results:Baseline blood flow and plasma ET-1, t-PA and PAI-1 concentrations were unaffected by bevacizumab. Bradykinin caused dose-dependent vasodilatation (P < 0.0001) and t-PA release (P < 0.01) but had no effect on plasma PAI-1 concentrations. Neither bevacizumab nor BQ-123 affected bradykinin-induced vasodilatation and t-PA release.Conclusion:Acute exposure to bevacizumab does not directly cause endothelial vasomotor or fibrinolytic dysfunction in healthy young volunteers.

Sulfenamide and Sulfonamide Derivatives of Metformin \u2013 A New Option to Improve Endothelial Function and Plasma Haemostasis

Type 2 diabetes mellitus (T2DM) is a multi-factorial disease which can cause multiple organ dysfunction, including that of the vascular endothelium. The aim of the present study was to evaluate the effects of metformin, and its sulfenamide and sulfonamide derivatives (compounds 1–8) on the selected markers of endothelial function and blood coagulation. The integrity of endothelial cells(ECs) was examined using the real-time cell electric impedance system. Tissue Factor(TF) production, the release of von Willebrand Factor (vWF) and tissue plasminogen activator(t-PA) from ECs were determined using immunoenzymatic assays, while the process of platelet thrombus formation using the Total Thrombus-Formation Analysis System. Sulfenamide with n-butyl alkyl chain(3) does not interfere with ECs integrity, and viability (nCI(24h) = 1.03 ± 0.03 vs. 1.06 ± 0.11 for control), but possesses anticoagulation properties manifested by prolonged platelet-dependent thrombus formation (Occlusion Time 370.3 ± 77.0 s vs. 286.7 ± 65.5 s for control) in semi-physiological conditions. Both p- and o-nitro-benzenesulfonamides (compounds7,8) exhibit anti-coagulant properties demonstrated by decreased vWF release and prolonged parameters of platelet thrombus formation and total blood thrombogenicity. In conclusion, chemical modification of metformin scaffold into sulfenamides or sulfonamides might be regarded as a good starting point for the design and synthesis of novel biguanide-based compounds with anticoagulant properties and valuable features regarding endothelial function.

An activated-platelet-sensitive nanocarrier enables targeted delivery of tissue plasminogen activator for effective thrombolytic therapy

It remains a major challenge to develop a selective and effective fibrinolytic system for thrombolysis with minimal undesirable side effects. Herein, we report a multifunctional liposomal system (164.6 ± 5.3 nm in diameter) which can address this challenge through targeted delivery and controlled release of tissue plasminogen activator (tPA) at the thrombus site. The tPA-loaded liposomes were PEGylated to improve their stability, and surface coated with a conformationally-constrained, cyclic arginine–glycine–aspartic acid (cRGD) to enable highly selective binding to activated platelets. The in vitro drug release profiles at 37 °C showed that over 90% of tPA was released through liposomal membrane destabilization involving membrane fusion upon incubation with activated platelets within 1 h, whereas passive release of the encapsulated tPA in pH 7.4 PBS buffer was 10% after 6 h. The release of tPA could be readily manipulated by changing the concentration of activated platelets. The presence of activated platelets enabled the tPA-loaded, cRGD-coated, PEGylated liposomes to induce efficient fibrin clot lysis in a fibrin-agar plate model and the encapsulated tPA retained 97.4 ± 1.7% of fibrinolytic activity as compared with that of native tPA. Furthermore, almost complete blood clot lysis was achieved in 75 min, showing considerably higher and quicker thrombolytic activity compared to the tPA-loaded liposomes without cRGD labelling. These results suggest that the nano-sized, activated-platelet-sensitive, multifunctional liposomes could facilitate selective delivery and effective release of tPA at the site of thrombus, thus achieving efficient clot dissolution whilst minimising undesirable side effects.

Graft Neutrophil Sequestration and Concomitant Tissue Plasminogen Activator Release During Reperfusion in Clinical Kidney Transplantation

BackgroundInflammation, coagulation, and fibrinolysis are tightly linked together. Reperfusion after transient ischemia activates both neutrophils, coagulation, and fibrinolysis. Experimental data suggest that tissue plasminogen activator (tPA) regulates renal neutrophil influx in kidney ischemia and reperfusion injury. MethodsIn 30 patients undergoing kidney transplantation, we measured renal neutrophil sequestration and tPA release from blood samples drawn from the supplying artery and renal vein early after reperfusion. tPA antigen levels were measured using a commercial enzyme-linked immunosorbent assay kit. For each parameter, transrenal difference (Δ) was calculated by subtracting the value of the arterial sample (ingoing blood) from the value of the venous sample (outgoing blood). ResultsPositive transrenal gradients of tPA antigen occurred at 1 minute [Δ = 14 (3–46) ng/mL, P < .01] and 5 minutes [Δ = 5 (-3 to 27) ng/mL, P < .01] after reperfusion. At 5 minutes after reperfusion, a negative transrenal gradient of neutrophils was observed [Δ = -0.17 (-1.45 to 0.24) x 10E9 cells/L, P < .001]. At 1 minute after reperfusion, neutrophil sequestration into the kidney (ie, negative transrenal neutrophil count) correlated significantly with tPA release from the kidney (ie, positive transrenal tPA concentration), (R = -0.513 and P = .006). ConclusionsThe findings suggest a proinflammatory role for tPA in ischemia and reperfusion injury in human kidney transplantation.

Tissue-type plasminogen activator regulates p35-mediated Cdk5 activation in the postsynaptic terminal.

Neuronal depolarization induces the synaptic release of tissue-type plasminogen activator (tPA). Cyclin-dependent kinase-5 (Cdk5) is a member of the family of cyclin-dependent kinases that regulates cell migration and synaptic function in postmitotic neurons. Cdk5 is activated by its binding to p35 (also known as Cdk5r1), a membrane-anchored protein that is rapidly degraded by the proteasome. Here, we show that tPA prevents the degradation of p35 in the synapse by a plasminogen-dependent mechanism that requires open synaptic N-methyl-D-aspartate (NMDA) receptors. We show that tPA treatment increases the abundance of p35 and its binding to Cdk5 in the postsynaptic density (PSD). Furthermore, our data indicate that tPA-induced p35-mediated Cdk5 activation does not induce cell death, but instead prevents NMDA-induced ubiquitylation of postsynaptic density protein-95 (PSD-95; also known as Dlg4) and the removal of GluR1 (also known as Gria1)-containing α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptors from the PSD. These results show that the interaction between tPA and synaptic NMDA receptors regulates the expression of AMPA receptor subunits in the PSD via p35-mediated Cdk5 activation. This is a novel role for tPA as a regulator of Cdk5 activation in cerebral cortical neurons.

Platelet-Mimic uPA Delivery Nanovectors Based on Au Rods for Thrombus Targeting and Treatment

Systemic thrombolytic drug administration has always gained an unideal therapeutic effect due to the rapid neutralization by its antidotes. It is significant to seek an approach for targeted thrombolytic drug delivery to the thrombus. Here a biocompatible, thrombus-targeted, and low-cost platelet-mimic nanovector was fabricated to accomplish a sustained urokinase plasminogen activator (uPA) release at the thrombus site. The prepared system presented a sustained model drug release behavior for 30 h and burst release behavior under near-infrared laser irradiation with hyperthermia in vitro. We demonstrate that the fabricated nanovectors can arrive and aggregate at the pulmonary thrombus, followed by a sustained uPA release in the murine pulmonary embolism model. Therefore, according to the results, the formulated nanovector presented a hopeful application for targeted thrombolytic therapy clinically.

Heparin promotes recanalization of venous thrombotic occlusions.

Thrombosis is a consequence of disbalance between the procoagulant and fibrinolytic activity of blood and is frequently associated with chronic sequelae, which are the consequence of chronic occlusion of affected veins. Treatment of venous thrombosis should not be oriented in the prevention of thrombus progression and associated thromboembolic events, but also in stimulation of thrombolysis and recanalization of occluded veins, which are one of the most important preventive mechanisms of late sequelae, including post-thrombotic syndrome. The treatment of acute venous thrombosis (superficial and deep) is based on drugs with anticoagulant activity, like antagonists of vitamin K, heparins, and new oral anticoagulants. One of the most frequently used anticoagulant drugs is heparin, particularly the low molecular weight heparin (LMWH). It was shown that besides strong anticoagulant activity heparin has pro-fibrinolytic effects, which promote thrombolysis and recanalization of occluded veins. LMWH markedly increases tissue factor pathway inhibitor levels and a release of tissue plasminogen activator from vascular endothelium. Heparins are also capable of increasing the nitrogen oxide level, which is responsible for circulatory homeostasis.

Anxiety-Related Bleeding and Thrombosis.

Anxiety, a normal response to stressful situations, is characterized by increased levels of factor VIII, fibrinogen, and von Willebrand factor, and by enhanced platelet aggregability. One would expect acute anxiety to be a prothrombotic state, but since acute mental stress induces tissue plasminogen activator (tPA) release from endothelial and chromaffin cells, fibrinolysis counteracts procoagulant stimuli. It could be said that procoagulant changes accompanying the fight-or-flight response reduce the risk of bleeding in case of potential injuries, while activation of fibrinolysis counteracts activation of hemostasis to prevent intravascular thrombus formation before injuries occur. Acutely anxious patients are prone to bleeding or thrombosis when the balance between hypercoagulation and hyperfibrinolysis is disturbed. Acute anxiety not only increases the risk of bleeding in hemophilia or von Willebrand disease, but many reports have shown that anxiolytic interventions such as hypnosis are effective in controlling bleeding in hemostatic disorders. The pathogenesis of cardiovascular and thrombotic diseases in highly anxious patients is multifactorial. An important element is α-adrenergic vasoconstriction, which increases viscosity due to leakage of intravascular fluid into the interstitium, and also causes hypertension, favoring plaque rupture. Paradoxical as it may seem, over secretion of tPA may increase cardiovascular risk. This is because tPA degrades the extracellular matrix, causing vascular stiffness that increases cardiac workload, and thus oxygen requirements. Anxious patients with conditions associated with increased plasminogen activator inhibitor-1 levels, such as depression or postprandial hyperinsulinemia, are at high risk of thrombosis. Postprandial hyperinsulinemia may result from consumption of high-carbohydrate foods, considered anxiolytic, combined with a sedentary life, which is common among anxious individuals. Preliminary evidence suggests that high anxiety combined with either depression or a lifestyle that results in hyperinsulinemia has an important role in the pathogenesis of thrombotic events currently classified as unprovoked.

Evaluating the Role of the Na+‐H+ Exchanger Isoform 1 (NHE1) in Lysophosphatidic Acid and Urokinase‐type Plasminogen Activator Stimulation of Ovarian Cancer Cells

Lysophosphatidic Acid (LPA) is a bioactive lipid which stimulates an increase in cell proliferation and migration in a range of normal and cancer lines in part through the activation of both the RhoA/Rock and Ras/ErK signaling pathways. Plasma levels of LPA are elevated in ovarian cancer patients even in the early stages of the disease where it is believed to participate in pathogenesis. In patients with more advanced stages of ovarian cancer, the higher the levels of LPA found in the blood and ascites is a negative prognostic indicator. In ovarian cancer, LPA enhances cell proliferation and promotes cell survival by preventing apoptosis and anoikis. LPA also decreases the sensitivity of the ovarian cancer cells to cisplatin and other chemotherapy drugs. While LPA signaling can directly enhance ovarian cancer progression, it can also act by stimulating the production and release of urokinase‐type plasminogen activator (uPA). uPA is a serine protease that binds to a plasma membrane receptor stimulating activation of both the RhoA/Rock and Ras/ErK signaling pathways. Studies in non‐small cell lung cancer cells have shown that LPA and uPA activate the Na+‐H+ Exchanger Isoform 1 (NHE1) leading to an increase in cell proliferation and migration. NHE1 is an 815 amino acid transmembrane protein that exchanges 1 extracellular Na+ for 1 intracellular H+ leading to the pH inversion common to cancer cells in a developing tumor. Activation of NHE1 is one of the initial steps in the development of the transformed phenotype of cancer cells. NHE1 can be phosphorylated and activated by Rock and kinases in the Ras/Erk signaling pathway. Recently, increases in NHE1 expression was demonstrated to play an important role in cancer progression in ovarian cancer patients. In this project, we specifically explore the relationship between LPA and uPA signaling to NHE1 in the regulation of cell proliferation, stress fiber formation, and cell migration in three ovarian cancer cell lines, CAOV‐3, SKOV‐3, and OVCAR‐3.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Tissue-type plasminogen activator protects the postsynaptic density in the ischemic brain

Cerebral ischemia causes the presynaptic release of tissue-type plasminogen activator (tPA). The postsynaptic density (PSD) is a postsynaptic structure that provides a matrix where signaling transduction of excitatory synapses takes place. The postsynaptic density protein-95 (PSD-95) is the most abundant scaffolding protein in the postsynaptic density (PSD), where it modulates the postsynaptic response to the presynaptic release of glutamate by regulating the anchoring of glutamate receptors to the PSD. We found that tPA induces the local translation of PSD-95 mRNA and the subsequent recruitment of PSD-95 protein to the PSD, via plasminogen-independent activation of TrkB receptors. Our data show that PSD-95 is removed from the PSD during the early stages of cerebral ischemia, and that this effect is abrogated by either the release of neuronal tPA, or intravenous administration of recombinant tPA (rtPA). We report that the effect of tPA on PSD-95 is associated with inhibition of the phosphorylation and recruitment of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors to the PSD, known to amplify the effect of the excitotoxic injury, and that this is followed by TrkB-mediated protection of dendritic spines from the harmful effects of the hypoxic insult. These data reveal that tPA is a synaptic protector in the ischemic brain.

Endothelial cell functions impaired by interferon in vitro: Insights into the molecular mechanism of thrombotic microangiopathy associated with interferon therapy

IntroductionInterferon (IFN)-α and IFN-β approved for treatment of chronic hepatitis C viral infection and multiple sclerosis respectively have been linked to thrombotic microangiopathy (TMA) affecting renal function. Since the molecular mechanisms underlying this severe complication remain largely unclear, we aimed to investigate whether IFN affects directly in vitro endothelial cell functions associated with angiogenesis and blood haemostasis, as well as endothelial cell-derived vasodilators of nitric oxide (NO) and prostacyclin. MethodsProliferation and survival of human umbilical vein endothelial cells (HUVECs) were measured by BrdU incorporation and alamarBlue assays. Angiogenesis was evaluated in co-cultures of HUVECs and human dermal fibroblasts. Fibrinolysis molecules were measured with ELISA. NO and prostacyclin were measured using a fluorescent NO-specific probe and a competitive enzyme immunoassay, respectively. ResultsHUVEC proliferation was dose-dependently inhibited by IFN-β1a and IFN-β1b, but not by IFN-α2a and IFN-α2b. Consistently, IFN-β1a and IFN-β1b also reduced survival of HUVECs, but this again was not observed with IFN-α. However, both IFN subtypes inhibited VEGF-induced development of capillary-like structures, but the effect of IFN-α was less potent than IFN-β. In addition, both IFN subtypes upregulated interferon inducible protein 10 production from treated co-cultures while suppressing angiogenesis. Furthermore, intracellular NO generation was reduced by IFN-α2a and IFN-β1a, whereas prostacyclin release from HUVECs was not affected by IFN. Importantly, both IFN-β1a- and IFN-β1b-treated HUVECs showed a marked reduction in urokinase-type plasminogen activator release and a much greater secretion of plasminogen activator inhibitor-1 than tissue-type plasminogen activator compared with untreated cells, suggesting decreased fibrinolytic activity. IFN-α, however was less effective in modulating the fibrinolysis system. ConclusionsWe demonstrate the detrimental effects of IFN on endothelial cell functions mediated with angiogenesis and fibrinolysis, which could potentially cause the loss of physiological endothelium thromboresistance and facilitate the development of vascular complications in a clinical setting. Mechanistically, our findings have implications for understanding how IFN therapy can foster the development of TMA.

Рідкісний випадок спонтанного тромболізису у пацієнтки з гострим інфарктом міокарда з елевацією сеґмента ST

In the pathogenesis of acute myocardial infarction an important role belongs to coronary sclerosis and coronary artery thrombosis. Endothelium plays an important role in a regulation of vascular tone, local inflammation, hemostasis, neovascularisation. An impairment of endothelial barrier function occurs after direct damage of endothelial cells as a result of an atherosclerotic plaque destabilization, injury, chronic inflammation or exposure to hazardous substances. Breakage of the endothelial surface causes an exposure of subendothelial collagen and triggers expression of adhesive proteins (e.g. tissue factor and von Willebrand factor) and decreases synthesis of prostacyclin and nitric oxide. In case of its damage and activation, thrombocytes adhere and aggregate to each other which leads to thrombosis and can cause an acute myocardial infarction.&nbsp; Aim.&nbsp;Our aim was to evaluate a cellular mechanisms of thrombosis as well as conditions that leads to spontaneous thrombolysis in acute myocardial infarction for treatment optimisation of acute coronary syndrome. &nbsp; Material and Methods.&nbsp;The case of acute myocardial infarction with ST segment elevation in 79 years old patient is presented that showed spontaneous coronary blood flow recovery.&nbsp; Results and Discussion.&nbsp;In described case in a patient with acute myocardial infarction a rapid regression of ECG changes were documented after medical treatment at home was provided. Those changes were most likely a results of spontaneous thrombolysis with subsequent recovery of coronary blood flow in infarct-related artery due to rarely occurring activation of fibrinolytic system. The fibrinolysis system was triggered by the release of plasminogen activator and affected newly formed thrombus. However unstable atherosclerotic plaque was thrombogenic enough and leaded to recurrence of myocardial infarction. Thus the patient received coronary artery stenting. Clinical and morphological data has shown that in those patients a major role in development of acute coronary syndrome plays not a coronary artery spasm but a coronary thrombosis with subsequent spontaneous thrombolysis and restoration of coronary blood flow which happened upon timely application of antiaggregants, anticoagulants and antianginals drugs. Coronary artery spasm typically occurs more distal from the obstruction place as a result of exposure to vasoconstrictors released after thrombocyte degranulation. Spontaneous thrombolysis by acute myocardial infarction is untypical, hence myocardial infarction with pathological Q wave develops.&nbsp; Conclusions.&nbsp;Patients with acute coronary syndrome, which exhibit spontaneous thrombolysis require angiography and stenting of coronary arteries as soon as possible to prevent recurrence of coronary thrombosis and development of acute myocardial infarction.

Nebivolol, But Not Metoprolol, Treatment Improves Endothelial Fibrinolytic Capacity in Adults With Elevated Blood Pressure.

BackgroundVascular endothelial fibrinolytic function is impaired in adults with prehypertension and hypertension and plays a mechanistic role in the development of atherothrombotic events. The influence of β‐blockers on endothelial fibrinolysis is unknown. This study compared the effects of chronic nebivolol and metoprolol treatment on endothelial tissue‐type plasminogen activator (t‐PA) release in adults with elevated blood pressure (BP).Methods and ResultsForty‐four middle‐aged adults (36% women) with elevated BP completed a 3‐month, double‐blind, randomized, placebo‐controlled trial comparing nebivolol (5 mg/d), metoprolol succinate (100 mg/d), and placebo. Net endothelial t‐PA release was determined in vivo in response to intrabrachial infusions of bradykinin and sodium nitroprusside before and after each intervention. In a subset, the dose‐response curves to bradykinin and sodium nitroprusside were repeated with a coinfusion of the antioxidant vitamin C. At baseline, resting BP and endothelial t‐PA release were comparable between the 3 groups. BP decreased to a similar extent (≈10 mm Hg) in the nebivolol‐ and metoprolol‐treated groups. There was a substantial increase (≈30%; P<0.05) in the capacity of the endothelium to release t‐PA following chronic treatment with nebivolol but not metoprolol or placebo. Mitigating oxidant stress with vitamin C coinfusion potentiated t‐PA release (90%; P<0.05) at baseline in all groups. However, after the intervention, t‐PA release was unchanged by vitamin C coinfusion in the nebivolol group only.ConclusionsNebivolol but not metoprolol improves endothelial t‐PA release in adults with elevated BP. This may be an important vascular benefit of nebivolol.Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01595516.

Tranexamic Acid for the Management of Obstetric Hemorrhage.

Obstetric hemorrhage remains the most common cause of maternal mortality worldwide. It is believed that increased fibrinolytic activity, secondary to release and activation of endothelial tissue plasminogen activator, is involved in its pathogenesis. Tranexamic acid (TXA), an antifibrinolytic agent, has been shown to be beneficial in trauma patients if used within 3 hours of injury. A recent large randomized controlled trial showed that TXA given to hemorrhaging women within 3 hours after delivery was associated with decreased risk of death resulting from bleeding with no increase in thromboembolic complications. Limited evidence suggests that prophylactic TXA reduces blood loss at the time of delivery and decreases transfusion rates in the obstetric population. Tranexamic acid appears to be a safe and effective option in the treatment of obstetric hemorrhage. In addition, the limited available evidence supports the need for a well-designed adequately powered clinical trial to test its benefit as a prophylactic agent.

Tissue-type plasminogen activator is a homeostatic regulator of synaptic function in the central nervous system.

Membrane depolarization induces the release of the serine proteinase tissue-type plasminogen activator (tPA) from the presynaptic terminal of cerebral cortical neurons. Once in the synaptic cleft this tPA promotes the exocytosis and subsequent endocytic retrieval of glutamate-containing synaptic vesicles, and regulates the postsynaptic response to the presynaptic release of glutamate. Indeed, tPA has a bidirectional effect on the composition of the postsynaptic density (PSD) that does not require plasmin generation or the presynaptic release of glutamate, but varies according to the baseline level of neuronal activity. Hence, in inactive neurons tPA induces phosphorylation and accumulation in the PSD of the Ca2+/calmodulin-dependent protein kinase IIα (pCaMKIIα), followed by pCaMKIIα-induced phosphorylation and synaptic recruitment of GluR1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. In contrast, in active neurons with increased levels of pCaMKIIα in the PSD tPA induces pCaMKIIα and pGluR1 dephosphorylation and their subsequent removal from the PSD. These effects require active synaptic N-methyl-D-aspartate (NMDA) receptors and cyclin-dependent kinase 5 (Cdk5)-induced phosphorylation of the protein phosphatase 1 (PP1) at T320. These data indicate that tPA is a homeostatic regulator of the postsynaptic response of cerebral cortical neurons to the presynaptic release of glutamate via bidirectional regulation of the pCaMKIIα /PP1 switch in the PSD.

Improving Antiadhesion Effect of Thermosensitive Hydrogel with Sustained Release of Tissue-type Plasminogen Activator in a Rat Repeated-Injury Model.

Intraperitoneal adhesion occurs frequently after pelvic and abdominal surgery, which plays an enormous burden on patients. Various drugs and barrier agents were studied and used to prevent adhesions, but few of them were satisfactory. A thermosensitive hydrogel was developed in our previous work and was effective in preventing adhesions. But in our preliminary experiment, it showed limited activity in a more rigorous rat repeated-injury adhesion model, which was much closer to clinical. In this study, tissue-type plasminogen activator (tPA) loaded thermosensitive hydrogel (tPA-hydrogel) was prepared, which combined barrier functions with sustained release of antiadhesion drug. The obtained tPA-hydrogel was injectable and degraded in vivo gradually in four weeks. Both hematoxylin and eosin and Masson trichrome staining confirmed that the tPA-hydrogel exhibited excellent antiadhesion effects on repeated-injury adhesion. Scanning electron microscopy was used to observe the injured abdominal wall, and cecum remesothelialized after treated with tPA-hydrogel for 14 d. In addition, the PAI-1 and tPA levels were measured by enzyme-linked immunosorbent assay. Results showed the PAI-1 concentrations in peritoneal lavage fluids of tPA-hydrogel treated rats were lower than that of other groups, leading to decreased fibrin formation, while there were no significant differences observed in tPA blood levels at any point in time (P > 0.05). This study demonstrated that the effectiveness of thermosensitive hydrogel in preventing adhesions could be enhanced by delivering antiadhesion drugs, and the tPA-hydrogel might be a promising system for clinical application.

Cytokine and estrogen stimulation of endothelial cells augments activation of the prekallikrein-high molecular weight kininogen complex: Implications for hereditary angioedema

When the prekallikrein-high molecular weight kininogen complex is bound to endothelial cells, prekallikrein is stoichiometrically converted to kallikrein because of release of heat shock protein-90 (Hsp90). Although bradykinin formation is typically initiated by factor XII autoactivation, it is also possible to activate factor XII either by kallikrein, thus formed, or by plasmin. Because attacks of hereditary angioedema can be related to infection and/or exposure to estrogen, we questioned whether estrogen or cytokine stimulation of endothelial cells could augment release of Hsp90 and prekallikrein activation. We also tested release of profibrinolytic enzymes, urokinase, and tissue plasminogen activator (TPA) as a source for plasmin formation. Cells were stimulated with agonists, and secretion of Hsp90, urokinase, and TPA was measured in the culture supernatants by ELISA. Activation of the prekallikrein-HK complex was measured by using pro-phe-arg-p-nitroanilide reflecting kallikrein formation. Hsp90 release was stimulated with optimal doses of estradiol, IL-1, and TNF-α (10ng/mL) from 15minutes to 120minutes. TPA release was not augmented by any of the agonists tested but urokinase was released by IL-1, TNF-α, and thrombin (positive control), but not estrogen. Augmented activation of the prekallikrein-HK complex to generate kallikrein was seen with each agonist that releases Hsp90. Addition of 0.1% factor XII relative to prekallikrein-HK leads to rapid formation of kallikrein; factor XII alone does not autoactivate. IL-1, TNF-α, and estrogen stimulate release of Hsp90 and augment activation of the prekallikrein-HK complex to generate kallikrein and bradykinin. IL-1 and TNF-α stimulate release of urokinase, which can convert plasminogen to plasmin and represents a possible source for plasmin generation in all types of hereditary angioedema, but particularly hereditary angioedema with normal C1 inhibitor with a factor XII mutation. Both kallikrein and plasmin activate factor XII; kallikrein is 20 times more potent on a molar basis.

Current Pathological and Laboratory Considerations in the Diagnosis of Disseminated Intravascular Coagulation.

Systemically sustained thrombin generation in vivo is the hallmark of disseminated intravascular coagulation (DIC). Typically, this is in response to a progressing disease state that is associated with significant cellular injury. The etiology could be infectious or noninfectious, with the main pathophysiological mechanisms involving cross-activation among coagulation, innate immunity, and inflammatory responses. This leads to consumption of both pro- and anticoagulant factors as well as endothelial dysfunction and disrupted homeostasis at the blood vessel wall interface. In addition to the release of tissue plasminogen activator (tPA) and soluble thrombomodulin (sTM) following cellular activation and damage, respectively, there is the release of damage-associated molecular patterns (DAMPs) such as extracellular histones and cell-free DNA. Extracellular histones are increasingly recognized as significantly pathogenic in critical illnesses through direct cell toxicity, the promotion of thrombin generation, and the induction of neutrophil extracellular trap (NET) formation. Clinically, high circulating levels of histones and histone–DNA complexes are associated with multiorgan failure, DIC, and adverse patient outcomes. Their measurements as well as that of other DAMPs and molecular markers of thrombin generation are not yet applicable in the routine diagnostic laboratory. To provide a practical diagnostic tool for acute DIC, a composite scoring system using rapidly available coagulation tests is recommended by the International Society on Thrombosis and Haemostasis. Its usefulness and limitations are discussed alongside the advances and unanswered questions in DIC pathogenesis.

Stimulatory effect of an algal fucoidan on the release of vascular endothelial tissue-type plasminogen activator as a mechanism of fucoidan-mediated thrombolysis.

Identifying a pharmacological means for increasing the production of tissue-type plasminogen activator (t-PA) is always desirable to cure impaired production of this enzyme. An algal fucoidan has been shown to exhibit both novel thrombolytic and synergistic stimulatory effects in a mouse thrombosis model. The plasma levels of active t-PA were measured in mouse arterial thrombus models that were treated with various fucoidans to investigate the mechanism of thrombolysis. The mean plasma level of active t-PA after the infusion of fucoidan was 2.136 ± 0.231 ng/ml for nonthrombolytic Fucus fucoidan and 3.917 ± 0.0.529 ng/ml for thrombolytic Undaria fucoidan, which resulted in a 1.56-2.29-fold increase compared with the healthy control group (1.706 ± 0.194 ng/ml) and the untreated thrombus group (2.506 ± 0.301 ng/ml) (P < 0.01). An algal fucoidan has demonstrated to exert a thrombolytic and stimulatory effect via the induction of t-PA release in a dose-dependent manner in an arterial thrombosis model.