Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The classical 'cascade/waterfall' hypothesis formulated to explain in vitro coagulation organised the amplification processes into the intrinsic and extrinsic pathways. Recent molecular biology and clinical data indicate that tissue factor/factor-VII interaction is the primary cellular initiator of coagulation in vivo. The process of blood coagulation is divided into an initiation phase followed by a propagation phase. The discovery of tissue factor pathway inhibitor further supports the revised theory of coagulation. Tissue factor is also a signalling receptor. Recent evidence has shown that blood-borne tissue factor has an important procoagulant function in sepsis, atherosclerosis and cancer, and other functions beyond haemostasis such as immune function and metastases.
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PMID:Tissue factor and tissue factor pathway inhibitor. 1509 42

The present study was performed to compare the anti-coagulant efficiency of recombinant human activated protein C (rhAPC) in cord with that in adult plasma. RhAPC is a promising candidate to improve the outcome of severe sepsis. However, different anticoagulant efficiency of rhAPC in cord compared with adult plasma has to be expected due to physiological low plasma levels of tissue factor pathway inhibitor (TFPI) and antithrombin (AT) present in neonates, two inhibitors known to markedly influence the anticoagulant action of APC. Clot formation was induced in our experiments by addition of high (30 micro M) or low (20 pM) amounts of lipidated tissue factor (TF). High amounts of TF are conventionally applied in standard clotting assays, whereas plasma activation with low amounts of TF probably better matches the conditions in vivo. We demonstrate that under low coagulant challenge increasing amounts of rhAPC (0.1-0.5 micro g/ml final plasma concentration) dose-dependently prolonged clotting time and suppressed thrombin potential and prothrombin fragment 1+2 generation in both cord and adult plasma. The same was true for experiments performed under high coagulant challenge when 4-16 micro g/ml of rhAPC were added. Whereby, cord plasma was significantly more susceptible to addition of rhAPC in the presence of high amounts of TF and adult plasma was significantly more susceptible to addition of rhAPC in the presence of low amounts of TF. We demonstrate that increased anticoagulant efficiency of rhAPC in adult plasma under low coagulant challenge is attributable to the physiological high levels of TFPI and AT present in adults.
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PMID:The anticoagulant action of recombinant human activated protein C (rhAPC, Drotrecogin alpha activated): comparison between cord and adult plasma. 1511 51

Sepsis is caused by a dysregulated immune response to infection and, without intervention, can lead to septic shock and multiple organ failure. A leading cause of morbidity and mortality in intensive care units worldwide, severe sepsis is also associated with a considerable cost burden that places significant strain on global healthcare budgets. The development of an efficacious and cost-effective treatment strategy is therefore of vital importance to today's intensive care physicians. This paper will examine the pathophysiology of sepsis and multiple organ dysfunction before reviewing trials recently undertaken to investigate three potential anticoagulant therapies: antithrombin III, activated protein C, and tissue factor pathway inhibitor. Finally, other recent developments in the care of sepsis patients will be briefly examined.
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PMID:Role of the tissue factor pathway in the pathogenesis and management of multiple organ failure. 1516 28

Recombinant activated protein C (APC), a well-defined anticoagulant enzyme, reduced mortality in severe sepsis patients in a phase 3 trial. However, 2 potent anticoagulants, antithrombin III and recombinant tissue factor pathway inhibitor, failed to do so, implying the physiologic relevance of APC's less well-defined anti-inflammatory and antiapoptotic activities. Recombinant APC therapy conveys an increased risk of serious bleeding complications due to APC anticoagulant activity. To generate recombinant APC variants with reduced risk of bleeding due to reduced anticoagulant activity, we dissected APC's anticoagulant activity from its cytoprotective activity by site-directed mutagenesis. Using staurosporine-induced endothelial cell apoptosis assays, we show here that Ala mutations (RR229/230AA and KKK191_ 193AAA) in 2 APC surface loops that severely reduce anticoagulant activity result in 2 APC variants that retain normal antiapoptotic activity that requires protease activated receptor-1 and endothelial cell protein C receptor. Thus, it is possible to reduce anticoagulant activity while preserving antiapoptotic activity of recombinant APC variants. We suggest that therapeutic use of such APC variants may reduce serious bleeding risks while providing the beneficial effects of APC acting directly on cells.
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PMID:Activated protein C variants with normal cytoprotective but reduced anticoagulant activity. 1517 75

Hypercoagulability is widely associated with sepsis, inflammation, diabetes, cancers, aging, and many pathological conditions, resulting in life-threatening disseminated intravascular coagulation (DIC), venous thrombosis, thromboembolism, cardiovascular complications, or even deadly multiple organ failure. Relieving coagulation dysfunction is not only a task for research scientists but also a challenge for physicians. The development of effective anticoagulants is under way with the basic understanding of the pathophysiology of hypercoagulable state. In this overview, various anticoagulants will be discussed according to the proposed inhibitory target-sites along the extrinsic pathway that is believed to play an integral role in homeostasis. Anticoagulants generally fall into two broad categories as natural or pharmacological ones. Antithrombin (AT), activated protein C (APC), and tissue factor pathway inhibitor (TFPI) mainly constitute the natural anticoagulant system apart from the recently reported physiological components such as lipoproteins, sphingosine, thrombomodulin (TM) or cellular Marcks protein. Pharmacological anticoagulants include warfarin, FVIIa inhibitors, FXa inhibitors, and thrombin inhibition by its direct inhibitors or heparins. In addition, a group of novel compounds inhibiting TF-dependent FVII activation result in anticoagulation; such upstream downregulation in the extrinsic pathway awaits further research to establish their in vivo benefits. The molecular genetic approaches such as developing soluble TF, FVII and thrombin mutants provide unique downregulation. Anticoagulation also extends its significance to anti-inflammation, making broad impacts on the improvement of human health.
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PMID:Biochemical strategies to anticoagulation: a comparative overview. 1532 Aug 20

Burn and septic injuries induce profound changes in coagulation status. This study examined the changes in plasma tissue factor pathway inhibitor (TFPI) and thrombin activatable fibrinolytic inhibitor (TAFI) levels in a rat model of burn and septic injuries. Rats underwent 30% TBSA cutaneous scald burn injury and septic insult was induced by caecal ligation and puncture (CLP). CLP was superimposed on burn injury to mimic the clinical model of sepsis complicating burn injury. Rats were pretreated with Cprofloxacin orally to colonize their gut with Enterococcus faecalis. TFPI and TAFI plasma levels were measured using functional activity assay kit with a chromogenic method at 24 and 72 hours following the injuries. TFPI levels decreased significantly at 24 hours in burn, CLP, and burn+CLP groups, followed by incomplete rebound recovery at 72 hours in all three groups. On the other hand, TAFI levels increased significantly at 24- and 72-hour time points in all three groups. These results suggest that burn, septic, and their combined injuries perturb coagulation cascade and thrombotic process toward the procoagulant pathway by impairing fibrinolysis.
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PMID:Tissue factor pathway inhibitor and thrombin activatable fibrinolytic inhibitor plasma levels following burn and septic injuries in rats. 1549 25

Based on the increasing knowledge of defects in haemostasis in patients with sepsis as well as on the non-conclusive results of studies which tried to increase the prognosis by modulating cytokine response of the patients, in the last years the impact of therapeutic modulation of coagulation in sepsis has been investigated. In contrast to the results of phase III studies with the coagulation inhibitors antithrombin and tissue factor pathway inhibitor recombinant human activated protein C (rhAPC) resulted in a significant reduction in mortality for the whole study population. Data analyses showed, that treatment with rhAPC was clinically beneficial especially in patient groups who showed a high mortality in the placebo arm. Inhibition of thrombus formation due to the therapy with natural coagulation inhibitors resulted in an increase of sepsis-imminent haemorrhage, which became significant in some studies. Treatment with antithrombin and heparin resulted in a considerable increase in bleeding complications and on the other hand, may have antagonized the expected effect of antithrombin on the patient's prognosis. Some results suggesting beneficial effects of heparin on patient prognosis in the placebo arms and on the other hand negative effects of heparin in the verum arms -- especially with antithrombin or tissue factor pathway inhibitor -- let to a controversial discussion of the risk/benefit relation of heparin, given in prophylactic doses to patients with severe sepsis. Whereas the impact and optimal application of heparin to patients with severe sepsis needs to be clarified study results with rhAPC resulted in the approval of this therapy and the implementation in the guidelines of the treatment of patients with severe sepsis.
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PMID:[Therapeutic modulation of coagulation in sepsis]. 1592 57

Tissue factor pathway inhibitor (TFPI) is a physiological inhibitor of extrinsic pathway of coagulation and has biological functions of anticoagulation and anti-inflammation. Although TFPI has been proved to be a good therapeutic agent of sepsis, inflammatory shock, and DIC, the clinical application and therapeutic effects of TFPI are impeded because of its short half-life in vivo. In order to prolong the half-life of TFPI, homology modeling and molecule docking were performed on a computer workstation principally in protein structural biology and binding characteristics between TFPI and its receptor LRP (low-density lipoprotein receptor related protein). Two recombinant long half-life human TFPI mutants coined TFPI-Mut1 and TFPI-Mut4 were designed and expressed in E.coli. In comparison with the wild-type TFPI, TFPI-Mut1 and TFPI-Mut4 presented a few of changes in spatial configuration and a decrease in relative Gibbs free energy of docking complex by 17.3% and 21.5%, respectively, as indicated by a computer simulation. After refolding and purification, anticoagulant activities, anti-TF/FVIIa and anti-FXa activities of the mutants were found to be the same as those of wide-type TFPI. The pharmacokinetics research indicated that alpha phase half-life (t1/2 alpha) of TFPI-Mut1 and TFPI-Mut4 were prolonged 1.33-fold and 1.96-fold respectively, beta phase half-life (t1/2 beta) of TFPI-Mut1 and TFPI-Mut4 were prolonged 1.62-fold and 4.22-fold respectively. These results suggested that TFPI-Mut1 and TFPI-Mut4 maintained the bioactivities of wild-type TFPI, prolonged half-life in vivo simultaneously and were expected for better clinical value and therapeutic effect.
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PMID:Molecular design and characterization of recombinant long half-life mutants of human tissue factor pathway inhibitor. 1596 88

Sepsis, a systemic inflammatory syndrome, is a response to infection and when associated with multiple organ dysfunction is termed severe sepsis. It remains a leading cause of mortality in the critically ill. The response to the invading microorganisms may be considered as a balance between a pro-inflammatory and an anti-inflammatory reaction. While an inadequate pro-inflammatory reaction and a strong anti-inflammatory response could lead to overwhelming infection and the death of the patient, a strong and uncontrolled pro-inflammatory response, manifested by the release of pro-inflammatory mediators may lead to microvascular thrombosis and multiple organ failure. Endotoxin triggers sepsis via the release of various mediators such as tumour necrosis factor-alpha and interleukin-1 (IL-1). These cytokines activate the complement and coagulation systems, release adhesion molecules, prostaglandins, leukotrienes, reactive oxygen species and nitric oxide. Other mediators involved in the sepsis syndrome include IL-1, -6 and -8; arachidonic acid metabolites; platelet activating factor; histamine; bradykinin; angiotensin; complement components and vasoactive intestinal peptide. These pro-inflammatory responses are counteracted by IL-10. Most of the trials targeting the different mediators of the pro-inflammatory response have failed due to a lack of correct definition of sepsis. Understanding the exact pathophysiology of the disease will enable more advanced treatment options. Targeting the coagulation system with various anticoagulant agents including, activated protein C, and tissue factor pathway inhibitor (TFPI) is a rational approach. Many clinical trials have been conducted to evaluate these agents in severe sepsis. While trials on antithrombin and TFPI were not so successful, the double-blind, placebo-controlled, Phase III trial of recombinant human activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) was successful, creating a significant decrease in mortality when compared to the placebo group. A better understanding of the pathophysiologic mechanism of severe sepsis will provide better treatment options, and combination antithrombotic treatment may provide a multipronged approach for the treatment of severe sepsis.
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PMID:Antithrombotic agents in the treatment of severe sepsis. 1598 40

The Kunitz-type proteinase inhibitor, tissue factor pathway inhibitor (TFPI), is the only endogenous inhibitor of the tissue factor (TF)-mediated coagulation pathway that plays a dominant role in normal haemostasis. TFPI exerts its action by binding to factor Xa (FXa) forming a TFPI-FXa complex that then, in a second step, binds and effectively inhibits the TF-factor VIIa (FVIIa) complex. Both full-length TFPI and chemically modified forms (e.g., truncated, glycosylated or phosphorylated TFPI variants) exert various pharmacological effects. The anticoagulant and antiplatelet actions of TFPI, its potency in inhibiting thrombin and FXa generation, as well as its favourable antithrombotic effectiveness seen in different animal models of venous and arterial thrombosis make this inhibitor a promising agent that could be potentially useful in several clinical indications. The inhibitory action of TFPI is accelerated by heparin. Heparin, as well as low molecular weight heparin (LMWH) derivatives, release TFPI from the vascular endothelium, an effect which seems to contribute mainly to the antithrombotic effectiveness of these drugs. The clinical relevance of TFPI is still undefined. Based on the beneficial actions in animal studies, as well as on the results obtained in first clinical investigations, TFPI is expected to be effective in the treatment of various diseases, such as disseminated intravascular coagulation, sepsis, coronary syndromes, stroke and acute respiratory distress syndrome (ARD). Further clinical trials should clarify the role of TFPI and more importantly define its potential usefulness as a prophylactic and/or therapeutic agent.
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PMID:Recombinant TFPI and variants: potential implications in the treatment of cardiovascular disorders. 1599 20


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