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1.
The objectives of present study were to investigate whether luteolin affects procoagulant proteinase activity and fibrin clot formation and influences thrombosis and coagulation in Sprague–Dawle rats. Luteolin significantly inhibited the enzymatic activity of thrombin and FXa activity by 29.1% and 16.2%. Luteolin also inhibited fibrin polymer formation in turbidity and microscopic analysis using fluorescent conjugate. Coagulation assay of luteolin was found to prolong activated partial thromboplastin time and prothrombin time. Moreover, luteolin protected the development of oxidative stress induced thrombosis in the FeCl3‐induced carotid arterial thrombus model. This study demonstrated that luteolin may be useful by reducing or preventing thrombotic challenge and can help us better understand the antithrombotic action of luteolin.  相似文献   

2.
A fibrinolytic metalloprotease with in vitro fibrinolytic effects was purified from the edible mushroom Pleurotus ferulae using several chromatography steps including anion and ion exchange, gel filtration, and fast protein liquid chromatography columns. The molecular mass of the enzyme was estimated to be 20.0?kDa, as determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fibrin zymography. The protease was active at 50°C, and pH 4.0, 5.0, and 8.0. The fibrinolytic activity of the enzyme was inhibited by ethyleneglycol-bis-(2-aminoethyl)-N,N,N′,N′ tetraacetic acid and strongly inhibited by two metal ions, Cu and Mg. In vitro assays evaluating fibrinolytic activity on a fibrin plate, fibrin turbidity, and thrombolytic activity on fibrin clots using human fibrinogen and human thrombin revealed that the enzyme could hydrolyze fibrin polymers directly and inhibit the formation of fibrin clots. In activated partial thromboplastin time (APTT) and prothrombin time assays, the enzyme strongly prolonged the APTT, which detects an activity of intrinsic and common pathways. The enzyme showed strong in vivo protective effect against mortality/paralysis from epinephrine plus collagen-induced acute thromboembolism in in vivo model. Our findings suggest that the enzyme may have a potential for treatment and prevention of thrombosis-relative diseases.  相似文献   

3.
目的:明确京尼平苷和京尼平的抗血栓和纤溶的作用效果。方法:用旁路循环血栓形成模型和颈总动脉血栓模型,测定CT、BT、PRT、PT,全血溶栓,计算血栓形成抑制率。结果:试验表明,京尼平苷及其苷元能显著延长凝血、出血时间,减少两个血栓模型的血栓重量,京尼平苷高剂量组与阳性药组相比,溶栓作用具有显著性差异(P<0.05),优于阳性药;京尼平、京尼平苷抗凝血及抗血栓作用与阿司匹林组相比无显著差异(P>0.05)。结论:实验表明中药栀子能延长凝血和出血时间,可能有一定的抗血栓和溶栓作用。  相似文献   

4.
The objective of this study is to establish a novel method for continuously monitoring thrombus progression with various outcome measures and to assess the efficacy of antithrombotic drugs in murine thrombosis model in mice. In the study, thrombus was induced in the femoral vein of mice by FeCl3 and monitored over time by spectral‐domain optical coherence tomography (OCT). Three‐dimensional images of thrombi with or without heparin as an antithrombotic agent were obtained from OCT angiography. In addition, several parameters of thrombi were analyzed and compared between control and anticoagulant groups. By using OCT, we were able to trace thrombus generation in the same mouse in real time. We found that in our model heparin reduced thrombus size by ~60% and thrombus cross‐sectional area by 50%. OCT results also show that both time to thrombus size (>0.02mm3) and time to occlusion (>30%) were significantly reduced after heparin addition. This study demonstrates that OCT reliably monitors thrombus generation and progression from various aspects including thrombus size. This enables us to measure the kinetic of thrombosis more accurately, and effectively evaluate the efficacy and activities of antithrombotic drugs. This model may represent a useful tool in antithrombotic drug discoveries in preclinical studies.   相似文献   

5.
A non-toxic, direct-acting fibrinolytic serine protease (Bafibrinase) demonstrating thrombolytic and anticoagulant properties was purified from Bacillus sp. strain AS-S20-I. Bafibrinase was monomeric, with a molecular mass of 32.3 kDa. The peptide mass fingerprinting of Bafibrinase revealed only 8.3% sequence coverage, suggesting it was a novel fibrinolytic enzyme. However, two of the tryptic digested de novo peptide sequences of Bafibrinase demonstrated good similarity with endopeptidases possessing serine in their catalytic triad. Further, catalytic activity of Bafibrinase was inhibited by serine protease inhibitor reinforcing this is a subtilisin-like serine protease. The apparent K(m) and V(max) values of Bafibrinase towards fibrin were determined as 0.24 μM and 2.8 μmol/min, respectively. It showed a K(m) value of 0.139 mM towards a chromogenic substrate for plasmin (D-Val-Leu-Lys-p-Nitroanilide dihydrochloride) and optimum activity at physiological conditions (37 °C and pH 7.4). Based on the cleavage pattern of fibrin and fibrinogen, Bafibrinase may be classified as an α,β-fibrinogenase. Bafibrinase could not degrade collagen and was non-cytotoxic to HT29 cells or mammalian erythrocytes. Further, Bafibrinase at a dose of 2 mg/kg was devoid of toxicity as well as hemorrhagic activity on BALB/c mouse model, supporting its suitability for the development of a better and safer thrombolytic drug. Bafibrinase was also superior to human plasmin in degrading in vitro thrombus. The in vivo anticoagulant nature of Bafibrinase is being explored for the treatment and prevention of thrombosis and other cardiovascular diseases.  相似文献   

6.
A direct acting antithrombotic serine protease (CCP) was purified from brown seaweed Costaria costata. CCP was a monomeric protease with molecular mass of 60,547.598 daltons as determined by mass spectrometry. The N-terminal sequence of CCP was SCNSCLDKVDADGLN. Proteolytic activity was inhibited by PMSF and APMSF. CCP exhibited high amidolytic activity toward substrate S-2251 with apparent Km and Vmax values were 14.5 μM and 183.5 U/ml respectively. Fibrin plate and fibrin zymography results revealed that CCP was able to degrade fibrin clots directly. It specifically hydrolyzed Aα and α and Bβ and β chains followed by γ and γ–γ chains of human fibrinogen and fibrin respectively. Cleavage of fibrin clot and fibrinogen was emphasized by observing the alteration of secondary structure using FTIR spectroscopy. Morphological alteration of fibrin clot was also evidenced by fluorescent microscopic observation. CCP reduced thrombus effectively in vitro. In vivo observation showed that it prevented/decreased thrombus formation in carrageenan-induced mice tail model. CCP prolonged activated partial thromboplastin time (APTT) and had little effect on prothrombin time (PT). Platelet function analyzer (PFA-100) tests showed that CCP prolonged closure time (CT). These data suggest that CCP could have therapeutic potential for the treatment of thrombosis.  相似文献   

7.
This study compared the antithrombotic effect of plasma angiotensin converting enzyme inhibitors (ACE-Is): captopril (CAP), enalapril (ENA) and tissue ACE-Is: perindopril (PER), quinapril (QUIN) in experimental venous and arterial thrombosis. Normotensive Wistar rats were treated p.o. with CAP (75 mg/kg), ENA (20 mg/kg), PER (2 mg/kg) and QUIN (3 mg/kg) for 10 days. The influence of ACE-Is on coagulation and fibrinolytic systems as well as platelet function was evaluated. The hypotensive effect of ACE-Is was equal in all groups. QUIN maintained the final carotid blood flow at the highest value in comparison to PER and plasma ACE-Is. The arterial thrombus weight was reduced in PER and QUIN groups while venous thrombus weight was also reduced after CAP. Tissue and plasma ACE-Is caused the inhibition of platelet adhesion and aggregation. A reduction of fibrin generation, prolongation of prothrombin time (PT), activated partial thromboplastin time (APTT) and shortening of euglobulin clot lysis time (ECLT) were observed after PER and QUIN treatment. In conclusion, given in equipotent hypotensive doses, tissue ACE-Is exerted more pronounced antithrombotic effect than plasma ACE-Is in experimental thrombosis. The differences between tissue and plasma ACE-Is in terms of their more pronounced inhibition of experimental thrombosis may be related to the intensified activation of fibrinolysis and inhibition of coagulation.  相似文献   

8.
The role of Asn-linked oligosaccharide in the functional properties of both human tissue-type plasminogen activator (t-PA) and a genetic variant of t-PA was studied. Nonglycosylated and glycosylated wild-type t-PA were produced in mammalian cells which express recombinant t-PA. These proteins were compared in fibrin binding and 125I-labeled fibrin clot lysis assays, using purified components. The nonglycosylated form showed higher fibrin binding, as well as higher fibrinolytic potency than the glycosylated form. Subsequently, prevention of glycosylation of a t-PA variant which lacked the finger and epidermal growth factor domains (delta FE), was carried out in an attempt to enhance its fibrinolytic activity. Glycosylation was prevented by changing Asn to Gln; at Asn-117 to produce delta FE1X t-PA, and at Asn-117, -184, and -448 to produce delta FE3X t-PA. All variants were similar to wild-type t-PA in their catalytic dependence on fibrinogen fragments, fibrinolytic activity in fibrin autography analysis, and plasminogen activator activity. In a clot lysis assay, using citrated human plasma, the fibrinolytic potency of the variants were comparable to that of wild-type t-PA at activator concentrations of 17-51 nM (approximately 1-3 micrograms/ml). At 0.5-5.1 nM (approximately 0.03-0.3 micrograms/ml), however, the variant proteins had lower fibrinolytic potency than wild-type t-PA. Fifty percent lysis in 1.5 h for wild-type, delta FE, delta FE1X, and delta FE3X t-PA, required 2.5, 10, 7.5, and 5.5 nM t-PA, respectively. The fibrinogenolytic activity in human plasma was measured for wild-type, delta FE, delta FE1X, and delta FE3X t-PA, and showed significant fibrinogen depletion after 3 h of incubation at 51 nM, decreasing to 11, 11, 50, and 72% of basal levels, respectively. These data indicate that partial or total nonglycosylated t-PA variants have a higher fibrinolytic versus fibrinogenolytic ratio than their fully glycosylated counterparts.  相似文献   

9.
The development of thrombolytic agent could provide invaluable progress for antithrombotic therapy. In this paper, we reported the cloning, purification and biochemical characterization of AnxB1ScuPAFap, a thrombus-ditargeting chimera composed of annexin B1, low molecular single-chain urokinase (ScuPA-32K) and fibrin-adherent peptide (dodecapeptide, Fap). In vitro test showed that, the chimera was a thrombolytic agent with anticoagulant activity and thrombus-ditargeting with the activated-platelet membrane binding and fibrin clot binding activity. Compared to urokinase, the chimera had less reperfusion time, higher reperfusion ratio, and less bleeding effects on coronary thrombolysis by clot lysis assay in dogs. Thus, the chimera appeared to be suitable for thrombolytic therapy of thrombus diseases.  相似文献   

10.
Fibrinolysis is a process responsible for the dissolution of formed thrombi to re‐establish blood flow after thrombus formation. Plasminogen activator inhibitor‐1 (PAI‐1) inhibits urokinase‐type and tissue‐type plasminogen activator (uPA and tPA) and is the major negative regulator of fibrinolysis. Inhibition of PAI‐1 activity prevents thrombosis and accelerates fibrinolysis. However, a specific antagonist of PAI‐1 is currently unavailable for therapeutic use. We screened a panel of uPA variants with mutations at and near the active site to maximize their binding to PAI‐1 and identified a potent PAI‐1 antagonist, PAItrap. PAItrap is the serine protease domain of urokinase containing active‐site mutation (S195A) and four additional mutations (G37bR–R217L–C122A–N145Q). PAItrap inhibits human recombinant PAI‐1 with high potency (Kd = 0.15 nM) and high specificity. In vitro using human plasma, PAItrap showed significant thrombolytic activity by inhibiting endogenous PAI‐1. In addition, PAItrap inhibits both human and murine PAI‐1, allowing the evaluation in murine models. In vivo, using a laser‐induced thrombosis mouse model in which thrombus formation and fibrinolysis are monitored by intravital microscopy, PAItrap reduced fibrin generation and inhibited platelet accumulation following vascular injury. Therefore, this work demonstrates the feasibility to generate PAI‐1 inhibitors using inactivated urokinase.  相似文献   

11.
Thrombosis is a leading cause of morbidity and mortality throughout the world. Thrombolytic agents are important for both the prevention and treatment of thrombosis. Fibrin clot and turbidity assays revealed that it was able to inhibit the formation of fibrin clot. Chlorogenic acid degraded blood clot and inhibited the enzymatic activity of procoagulant proteases, thrombin, activated factor X (FXa), and activated factor XIII (FXIIIa). Chlorogenic acid was found to delay activated partial thromboplastin time, prothrombin time, and thrombin time. PFA‐100 assays showed that it prolonged the closure time of citrated whole human blood. It demonstrated the antithrombotic effect in collagen and epinephrine‐induced acute thromboembolism mice model. These antithrombotic profiles together with its anticoagulant and platelet disaggregation properties, and lack of toxicity to NIH‐3T3 and 3T3‐L1 cells, make it a potential agent for thrombotic treatment and prevention.  相似文献   

12.
A fibrinolytic protease, wulfase, exhibiting antithrombotic potency was purified from the fruit bodies of Sparassis crispa Wulf. ex. Fr. Wulfase showed a single band of approximately 90 kDa by SDS-PAGE and fibrin zymography. The fibrinolytic activity of wulfase determined by fibrin plate assay revealed that it could directly degrade fibrin clot. The enzyme could inhibit activities of factor Xa and thrombin. Turbidity and electron-microscopy analysis using fluorescent conjugate demonstrated that wulfase also inhibited fibrin polymer formation. The anticoagulant effect of the enzyme was further confirmed in human plasma. These results suggest that wulfase may be useful for reducing or preventing thrombotic challenge.  相似文献   

13.
Quercetin-3-rutinoside inhibits thrombus formation in a mouse model by inhibiting extracellular protein disulfide isomerase (PDI), an enzyme required for platelet thrombus formation and fibrin generation. Prior studies have identified PDI as a potential target for novel antithrombotic agents. Using a fluorescence enhancement-based assay and isothermal calorimetry, we show that quercetin-3-rutinoside directly binds to the b′ domain of PDI with a 1:1 stoichiometry. The binding of quercetin-3-rutinoside to PDI induces a more compact conformation and restricts the conformational flexibility of PDI, as revealed by small angle x-ray scattering. The binding sites of quercetin-3-rutinoside to PDI were determined by studying its interaction with isolated fragments of PDI. Quercetin-3-rutinoside binds to the b′x domain of PDI. The infusion of the b′x fragment of PDI rescued thrombus formation that was inhibited by quercetin-3-rutinoside in a mouse thrombosis model. This b′x fragment does not possess reductase activity and, in the absence of quercetin-3-rutinoside, does not affect thrombus formation in vivo. The isolated b′ domain of PDI has potential as an antidote to reverse the antithrombotic effect of quercetin-3-rutinoside by binding and neutralizing quercetin-3-rutinoside.  相似文献   

14.
The fermented marine alga Porphyra dentata suspension was tested for its fibrinolytic and immune-enhancing activities. An isolated Bacillus subtilis N2 strain was selected for its fibrinolytic activity on fibrin plates. After investigating the effects of biomass amounts of P. dentata powder in water, various additives including sugars, nitrogen-containing substances, lipids and minerals, and cultural conditions of temperature and agitation in flask, the highest fibrinolytic activity in the cultural filtrate was obtained by cultivating N2 strain in 3% (w/v) P. dentata powder suspension containing 1% peanut oil at 37?°C, 150?rpm for 48?h. A fermentor system was further established using the same medium with controlled pH value of 7.0 at 37?°C, 150?rpm, 2.0 vvm for 48?h for the best fibrinolytic activity. The fermented product also showed its immune-enhancing activity by increasing cell proliferation and stimulating the secretion of IL-1β, IL-6, and TNF-α in J774.1 cells.  相似文献   

15.
THE human plasma protein, fibrinogen, is a disulphide bonded1 dimer2, each unit containing an Aα, Bβ and 8 chain*, interconnected by disulphide bridges3. Thrombin (E.C.3.4.4.-13) releases fibrinopeptides A and B from the Aα and Bβ chains respectively4 to form fibrin monomer (α2β2γ2) ? which polymerizes to form fibrin polymer or clotted fibrin. This polymer, following factor XIII (plasma transglutaminase, fibrin stabilizing factor) mediated crosslinking among the α chains and among the γ chains5, is one of the major and initiating constituents of a thrombus. Fibrinolytic activators, for example, streptokinase (SK) and urokinase (UK), are of thrombolytic value as they convert the thrombus plasminogen to plasmin (E.C.3.4.4.14) which by fibrinolytic action dissolves the thrombus. Whereas the interaction of fibrinogen and plasmin has been well studied6–9, little is known concerning the mechanism of plasmin mediated fibrin clot lysis. I report here on the mechanism of non-cross-linked fibrin clot solubilization in near physiological conditions.  相似文献   

16.
THERE are two principal theories of the mechanism of thrombus dissolution by the fibrinolytic system. Alkjaersig et al.1 suggested that as fibrin polymerizes, plasminogen is adsorbed preferentially to the fibrin and is available in large quantities within a thrombus which is comparatively free of antiplasmin. When an activator enters the circulation it diffuses into the clot converting the plasminogen to plasmin in situ and so promotes lysis. Ambrus and Markus2, however, proposed that when plasmin forms in the circulation naturally or during infusion of an activator it is normally bound to the excess antiplasmin present in blood. They suggested that this plasmin/antiplasmin complex is reversible and dissociates in the presence of fibrin, its preferred substrate, so allowing the plasmin to bring about fibrin dissolution by “external lysis”. Neither of these theories, however, is supported by an observed phenomena.  相似文献   

17.
Lumbrokinase (LK) is a group of serine proteases with strong fibrinolytic and thrombolytic activities and is useful for treating diseases caused by thrombus. Cholera toxin B subunit (CTB) has been widely used to facilitate antigen delivery by serving as an effective mucosal carrier molecule for the induction of oral tolerance. We investigate here the application of CTB as a transmucosal carrier in enhancing its fusion protein‐LKs effect to protect rats against thrombosis. Thus, in this study, CTB‐LK fusion gene separated by a furin cleavage site was expressed in seeds of Helianthus annuus L. The activity of recombinant protein in seeds of transgenic sunflower was confirmed by Western blot analysis, fibrin plate assays and GM1‐ganglioside ELISA. The thrombosis model of rats and mice revealed that the oral administration of peeled seeds of sunflower expressing CTB‐LK had a more significant anti‐thrombotic effect on animals compared with that administration of peeled seeds of sunflower expressing LK. It is possible to conclude that CTB can successfully enhance its fusion protein to be absorbed in rats or mice thrombosis model. The use of CTB as a transmucosal carrier in the delivery of transgenic plant‐derived oral therapeutic proteins was supported. In addition, for the purpose of that recombinant CTB‐LK was designed for oral administration, thus the expression of CTB‐LK in edible sunflower seeds eliminated the need for downstream processing of proteins. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1029–1039, 2014  相似文献   

18.
In a previous report we showed that plasmin-dependent lysis of a fibrin polymer, produced from purified components, was totally blocked if annexin II heterotetramer (AIIt) was present during fibrin polymer formation. Here, we show that AIIt inhibits fibrin clot lysis by stimulation of plasmin autodegradation, which results in a loss of plasmin activity. Furthermore, the C-terminal lysine residues of its p11 subunit play an essential role in the inhibition of fibrin clot lysis by AIIt. We also found that AIIt binds to fibrin with a K(d) of 436 nm and a stoichiometry of about 0.28 mol of AIIt/mol of fibrin monomer. The binding of AIIt to fibrin was not dependent on the C-terminal lysines of the p11 subunit. Furthermore, in the presence of plasminogen, the binding of AIIt to fibrin was increased to about 1.3 mol of AIIt/mol of fibrin monomer, suggesting that AIIt and plasminogen do not compete for identical sites on fibrin. Immunohistochemical identification of p36 and p11 subunits of AIIt in a pathological clot provides important evidence for its role as a physiological fibrinolytic regulator. These results suggest that AIIt may play a key role in the regulation of plasmin activity on the fibrin clot surface.  相似文献   

19.
Approximately 35 years ago, it was discovered that spontaneous fibrinolytic activity in blood showed a sinusoidal variation with a period of 24 h; it increased severalfold during the day, reaching a peak at 6:OO p.m. and then dropped to trough levels at 3:00–4:00 a.m. The range of the fluctuation and the 24-h mean levels were highly reproducible within an individual; moreover, the timing of the oscillation was remarkably consistent among individuals, with a fixed phase relationship to external clock time. The biorhythm could not be accounted for simply by variations in physical activity, body posture, or sleepfwake schedule. Gender, ethnic origin, meals, or resting levels of blood fibrinolytic activity also did not influence the basic features of the rhythm. Older subjects, compared to younger ones, showed a blunted diurnal increase in fibrinolytic activity in blood. Recent studies have established that, of the known components of the fibrinolytic system, only tissue-type plasminogen activator (tPA) and its fast-acting inhibitor, plasminogen activator inhibitor- 1 (PAL l), show a marked circadian variation in plasma. In contrast, levels of plasminogen, α2-antiplasmin, urinarytype plasminogen activator, and a reversible tPA inhibitor vary little or none during the 24 h. Quenching antibodies to tPA have shown that the circadian rhythm of fibrinolytic activity in blood is due exclusively to changes in tPA activity. However, the 24-h fluctuation of plasma tPA activity is phase shifted in relation to the rhythm of immunoreactive tPA, but shows a precise phase inversion with respect to the 24-h variation of PAL 1 activity and antigen. Therefore, plasma tPA activity, as currently measured in vitro, is tightly and inversely related to the levels of PAL 1 throughout the 24-h cycle. The factors controlling the rhythmicity of plasma PAI-1 are not fully elucidated but probably involve a humoral mechanism; changes in endothelial function, circulating platelet release. products, corticosteroids, catecholamines, insulin, activated protein C, or hepatic clearance do not appear to be responsible. Shift workers on weekly shift rotations show a disrupted 24-h rhythm of plasma tPA and PAL 1. In acute and chronic diseases, the circadian rhythmicity of fibrinolytic activity may show a variety of alterations, affecting the 24-h mean, the amplitude, or the timing of the fluctuation. It is advisable, therefore, to define the 24-h pattern of plasma tPA and PAI- 1 in patient groups, before levels based on a single blood sampling time are compared to those of a control population. In normal conditions, the 24-h variation of plasma tPA and PAI- 1 is not associated with parallel circadian changes in effective fibrinolysis, assessed as plasma D-dimer concentrations, presumably because fibrin generation in the circulation is low. In diseases in which fibrin formation is increased, however, the physiological drop of fibrinolytic activity in the morning hours may favour thrombus development at this time of day, in agreement with the reported higher morning frequency of acute thrombotic events.  相似文献   

20.
In order to find novel antiplatelet drugs for the treatment of ischemic stroke, a series of 3-butylphthalide derivatives containing isopentenylphenol moiety were designed, synthesized and characterized with spectroscopic analyses. The in vitro antiplatelet activity results indicated that compound 3 better inhibited the arachidonic acid (AA) induced platelet aggregation than aspirin (ASP) and 3-butylphthalide (NBP). Additionally, compared with precursor NBP, compound 3 possessed outstanding antithrombotic activity in the animal experiment model, which could effectively alleviate the formation of tail thrombus and carotid artery thrombus in mice. More importantly, intraperitoneal administration of compound 3 can well protected the rats against ischemia/reperfusion-induced brain injury. Further pharmacokinetic (PK) assay indicated that compound 3 had good absorption characteristics and metabolic stability in vivo. Overall, the present research provides a new candidate compound for the treatment of ischemic stroke caused by platelet aggregation.  相似文献   

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