Physiological Anticoagulants Research Articles

Age features of the hemostatic system in people with insulin resistance and prediabetic carbohydrate metabolism disorders

In pre-diabetes disorders in which pathogenesis the insulin resistance (IR) plays a leading role, the risk of thrombosis due to increased coagulation factors, decreased concentration of physiological anticoagulants and inhibition of fibrinolysis is increased. Similar changes in the hemostatic system with aging are observed. We investigated the characteristics of the hemostatic system in middle-aged and elderly people with IR in the absence and presence of impaired glucose tolerance (IGT). It is shown that IR in middle-aged and elderly people is accompanied by increased content of plasminogen activator inhibitor type-1, which may lead to potential inhibition of fibrinolysis. An indication of significant prothrombotic changes associated with IR in the elderly are reduced a clotting time of blood plasma in the APTT test and elevated levels of soluble fibrin and D-dimer. Intensity of these changes in the hemostatic system is enhanced in the presence of IGT. The results substantiate need for correction of hemostasis by reducing the IR.

Activated protein C retards recovery from coagulopathy in severe acute pancreatitis

Objectives: Activated protein C (APC), an endogenous anticoagulant, has antithrombotic, fibrinolytic and anti-inflammatory properties. We recently conducted a controlled study (APCAP, activated protein C in severe acute pancreatitis) of APC treatment of patients with severe acute pancreatitis (SAP). Here we studied the effect of APC on the pivotal coagulation parameters of the surviving patients in the APCAP study. Methods: The study consisted of 20 patients of whom 10 patients had received APC and 10 patients had received placebo. Coagulation parameters, physiological anticoagulants, thrombograms and circulating levels of IL-6 and CRP were determined on admission and at days 1, 3–4 and 6–7. Results: During follow-up, the temporal levels of prothrombin time (PT) decreased and the temporal levels of thromboplastin time (TT) increased in placebo group (p < 0.001 for both), but not in APC group. The temporal levels of antithrombin (AT) increased less in APC group than in placebo group (p = 0.011). The shapes of the SAP patients’ thrombograms were strongly deranged and were marginally affected by APC treatment. Conclusions: Coagulopathy in SAP, a complex phenomenon, is not alleviated by APC treatment. Rather, the patients receiving APC are heading toward normal homeostasis of coagulation slower than patients receiving placebo.

Ишемический инсульт в молодом возрасте и тромбофилии, обусловленные дефицитом или аномалиями физиологических антикоагулянтов

Ишемический инсульт в молодом возрасте и тромбофилии, обусловленные дефицитом или аномалиями физиологических антикоагулянтов

Acute traumatic coagulopathy.

Mortality from trauma remains a global public health challenge, with most preventable deaths due to bleeding. The recognition of acute traumatic coagulopathy as a distinct clinical entity characterized by early coagulation dysfunction, arising prior to medical intervention, has revolutionized trauma management over the last decade. The aim of this article is to review our current understanding of acute traumatic coagulopathy. We focus on recent advances in the mechanistic understanding of acute traumatic coagulopathy, particularly the changes in coagulation factors, physiological anticoagulants, endothelial activation, fibrinolysis and platelet dysfunction. Evolving diagnostic and therapeutic approaches are discussed, including viscoelastic coagulation monitoring and the role of tranexamic acid and blood products. Emphasis is now placed on early prevention, diagnosis, and aggressive initial treatment of coagulopathy and fibrinolysis with haemostatic blood products and tranexamic acid in addition to red cell units in order to reduce bleeding and improve clinical outcomes.

Activated protein C rescues the cochlea from noise-induced hearing loss

Activated protein C (APC) is a serine/threonine protease and a physiological anticoagulant that exerts anti-inflammatory and anti-apoptotic effects. Although recent studies have revealed that APC has the potential to protect endothelial cells from apoptosis, the mechanisms of its cytoprotective effect are not fully understood. We examined the potential of APC to protect against noise-induced hearing loss (NIHL) and investigated phosphorylation of serine-threonine kinase (Akt) and inhibition of apoptosis as possible cytoprotective mechanisms. We administered intraperitoneal injections of APC (150, 300U/kg) or normal saline to rats 30min before exposure to a sound pressure level (SPL) of 126dB and 4-kHz octave band noise for 5h. The auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) were measured before and after exposure. ABR and DPOAE measurements revealed greater improvement in the APC group than in the control group 28 days after exposure. Our examination of outer hair cells (OHCs) at 28 days after noise exposure revealed a significantly higher OHC survival rate in the APC group than in the control group. Immunohistochemical analyses for cleaved-caspase 3, phospho-p38 (p-p38), TUNEL, and phospho-Akt (p-Akt) revealed strong immunoreactivities against cleaved-caspase 3, p-p38, and TUNEL in the inner ear tissues of the control group; however, these signals were decreased in the APC group. Moreover, APC significantly induced activation of p-Akt in the cochlea. These findings suggest that APC has a novel protective effect on the cochlea against NIHL that is mediated by p-Akt and the anti-apoptotic signaling pathway.

Coagulation and protein-synthetic functions features of liver during formation of acute cholangitis induced by tumor of pancreaticoduodenal zone

The study of coagulation features and protein-synthetic function of blood in patients with cancer of pancreatoduodenal zone, complicated by mechanical jaundice and acute cholangitis was carried out. There are 106 patients included in this work, blood samples was taken at admission (day 1), 3-5 and 7-10 days after operation. Characteristic of hemocoagulation activity was studied by measuring the activity of coagulation factors V and VII. Protein-forming liver function was taken into account by measuring the activity of coagulation factors V and VII, as well as the main physiological anticoagulants - antithrombin III and protein C. The leading cause of blood coagulability reduction in examined patients was a disorder of the vitamin K - dependent factors synthesis (for example, factor VII) with the moderate changes of factor V, antithrombin III and protein C in the course of the disease.

Hemostatic changes in pregnancy

Normal pregnancy is associated with changes in all aspects of haemostasis, including increase in concentrations of most clotting factors, decreasing concentrations of some of the natural anticoagulants and diminishing fibrinolytic activity. These changes help in maintaining placental function during pregnancy but result in a state of hypercoagulability that may predispose to thrombosis and placental vascular complications. During pregnancy, the concentrations of coagulation factors V, VII, VIII, IX, X, XII and von Willebrand factor rise significantly, accompanied by a pronounced increase in fibrinogen levels which increases up to two-fold from non-pregnant levels. Furthermore, there is a decrease in physiological anticoagulants manifested by a significant reduction in protein S activity and by acquired activated protein C resistance. The overall fibrinolytic activity is impaired during pregnancy, but returns rapidly to normal following delivery. This is largely due to placental derived plasminogen activator inhibitor type 2 (PAI-2), which is present in substantial quantities during pregnancy. D-Dimer levels increase in pregnancy but are not thought to indicate intravascular coagulation as fibrinolysis is depressed. These D-Dimers may originate from the uterus. Finally, the platelet count decreases in normal pregnancy possibly due to increased destruction and haemodilution with a maximal decrease in the third trimester. Immediately after delivery there is an increase in platelet count, especially in patients undergoing cesarean section. During treatment of severe post-partum hemorrhage, it is absolutely essential to have the knowledge that the starting values of the platelets are very different as compared to a non-pregnant patient. Moreover, after delivery, also the levels of fibrinogen increase. Since the value of fibrinogen represents a crucial parameter for the management of acute bleeding, it is essential to administer the proper amount of fibrinogen in the case of postpartum hemorrhage. This aspect is emphasized especially in relation to the use of thromboelastography and for a correct interpretation of the results. Thromboelastogram profiles strongly depend on the amount of platelets and fibrinogen in whole blood. Protocols for thromboelastogram guided administration of hemocomponents and coagulation factor concentrates in cases of acute bleeding in pregnancy and post-partum are required.

Effect of Mild Hypothermia on the Coagulation-Fibrinolysis System and Physiological Anticoagulants after Cardiopulmonary Resuscitation in a Porcine Model

The aim of this study was to evaluate the effect of mild hypothermia on the coagulation-fibrinolysis system and physiological anticoagulants after cardiopulmonary resuscitation (CPR). A total of 20 male Wuzhishan miniature pigs underwent 8 min of untreated ventricular fibrillation and CPR. Of these, 16 were successfully resuscitated and were randomized into the mild hypothermia group (MH, n = 8) or the control normothermia group (CN, n = 8). Mild hypothermia (33°C) was induced intravascularly, and this temperature was maintained for 12 h before pigs were actively rewarmed. The CN group received normothermic post-cardiac arrest (CA) care for 72 h. Four animals were in the sham operation group (SO). Blood samples were taken at baseline, and 0.5, 6, 12, 24, and 72 h after ROSC. Whole-body mild hypothermia impaired blood coagulation during cooling, but attenuated blood coagulation impairment at 72 h after ROSC. Mild hypothermia also increased serum levels of physiological anticoagulants, such as PRO C and AT-III during cooling and after rewarming, decreased EPCR and TFPI levels during cooling but not after rewarming, and inhibited fibrinolysis and platelet activation during cooling and after rewarming. Finally, mild hypothermia did not affect coagulation-fibrinolysis, physiological anticoagulants, or platelet activation during rewarming. Thus, our findings indicate that mild hypothermia exerted an anticoagulant effect during cooling, which may have inhibitory effects on microthrombus formation. Furthermore, mild hypothermia inhibited fibrinolysis and platelet activation during cooling and attenuated blood coagulation impairment after rewarming. Slow rewarming had no obvious adverse effects on blood coagulation.

Thrombin generation in Cushing’s Syndrome: do the conventional clotting indices tell the whole truth?

Cushing's Syndrome (CS) is associated with an increased mortality, where hypercoagulability seems to have a crucial role in both arterial and venous thrombosis. Parameters of in vitro thrombin generation (TG) such as lag time, peak thrombin and endogenous thrombin potential (ETP), that describe the time until thrombin burst, the peak amount of TG and the total amount of thrombin generated, respectively as well as classical clotting markers were evaluated in 33 CS patients compared to both a group of 28 patients matched for the features of Metabolic Syndrome (MetS) and 31 healthy individuals. CS and MetS patients had shorter lag time (p<0.0001), higher peak and ETP (p<0.0001) than healthy controls, though lag time was less shortened in CS (p<0.0001) respect to MetS group. Prothrombin time (PT) was increased (p<0.0001) in both CS and MetS patients, while partial thromboplastin time (PTT) was shorter (p<0.0001) in CS compared to both MetS and healthy group (p<0.0001). Factor VIII (FVIII), Antithrombin (AT), protein C and S were increased only in CS patients (p<0.0001). lag time, AT and FVIII correlated to night salivary cortisol (r=+0.59; p=0.0005, r=+0.40; p=0.003, r=+0.40; p=0.04, respectively); PTT correlated inversely to urinary free cortisol (r=-0.45; p=0.009). BMI correlated negatively to lag time (r=-0.40; p=0.0001) and positively to peak and ETP (r=+0.34; p=0.001, r=+0.28; p=0.008, respectively). Obese and diabetic patients had shorter lag time (p=0.0005; p=0.0002, respectively), higher ETP (p=0.0006; p=0.007, respectively) and peak (p=0.0003; p=0.0005, respectively) as well as a more prolonged PT (p=0.04; p=0.009, respectively). Hypertensive individuals had higher ETP (p=0.004), peak (p=0.0008) and FVIII (p=0.001). Our findings confirm a prothrombotic state in both CS and MetS patients, though lag time was less shortened in CS. The high levels of endogenous physiological anticoagulants, could possibly represent a protective mechanism against hypercoagulability seen in CS patients.

Activities of Clotting, Fibrinolytic, and Anticoagulant Components of Plasma Hemostasis in Patients with Degenerative Diseases of Large Joints

Analysis of plasma hemostasis parameters was carried out in 110 patients with degenerative diseases of hip or knee joints hospitalized for initial endoprosthetics. Molecular markers of clotting and fibrinolysis and physiological anticoagulants were studied. Activities of all components of plasma hemostasis were normal in 29.4% patients. In 54.1% patients, high clotting activity was compensated for by adequate fibrinolysis activity. High thrombin formation was compensated for by high consumption of physiological anticoagulants in 10.1% patients. In 6.4% patients, high clotting activity was not paralleled by high fibrinolytic activity.

The hemostatic system in neonates whose mothers took antiepileptic agents during pregnancy

Objective : to study the frequency of thrombohemorrhagic events and the specific features of hemostatic parameters in neonatal infants whose mother have received antiepileptic agents (AEA) during pregnancy. Subjects and methods . One hundred and eighty-seven newborn infants were followed up. There was an absolute preponderance of valproic acid and carbamazepine among the drugs taken by the pregnant women. Hemostatic parameters were examined in the umbilical cord blood of 16 fullterm neonates. A control group consisted of 11 full-term neonatal infants of non-epileptic mothers who had received no AEA during pregnancy. The clinical follow-up showed no thrombohemorrhagic events in all 187 cases. A hemostatic study revealed a proportional reduction in the levels of procoagulants and physiological anticoagulants and an increase in the content of von Willebrand factor in Groups 1 and 2 (a control group). Overall, the hemostatic parameters in Groups 1 and 2 of the newborns did not significantly differ from those in healthy full-term neonates.

Recombinant Anticoagulant Factors for Adjunctive Treatment of Sepsis

Inflammation and coagulation play a pivotal role in the pathogenesis of sepsis. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation has major consequences for the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Important factors include endothelial-bound anticoagulant mechanisms, such as the antithrombin system, the (activated) protein C/thrombomodulin system, and tissue factor pathway inhibitor, which are all impaired during sepsis. Restoration of these anticoagulant pathways is currently evaluated in several clinical studies. Production of these physiological anticoagulants by recombinant technology greatly facilitates this adjunctive treatment strategy.

Flow Cytometric Analysis of Defense Functions of Hemocytes from the Penaeid Shrimp,Penaeus vannamei

Morphology and functions of hemocytes from Penaeus vannamei were analyzed by flow cytometry (FCM) on the basis of cellular structures and incorporation of fluorescent markers. In shrimps there were three types of circulating hemocytes (hyalinocytes, semi-granulocytes, and granulocytes) identified by FCM and light microscopy. Analysis of hemocytes after propidium iodide staining indicated that the majority of hemocytes were alive after been collected in the physiological anticoagulant. The phagocytic activity level of hemocytes was analyzed using fluorescent beads and the shrimp hemocytes showed different phagocytic activity that could be inhibited by sodium azide. Respiratory burst activity, which was measured using 2′,7′-dichlorofluorescein diacetate, can be stimulated by phorbol-12-myristate-13-acetate. Mitochondrial membrane potential was probed according to the accumulation of 3′,3′-dihexyloxacarbocyanine iodide in the mitochondrial matrix. The data showed more granular cells displayed higher fluorescence intensity than less granular hemocytes. FCM can rapidly, accurately, and directly quantify the morphology and function of a large number of individual cells, and will lead to a better understanding of the shrimp immune system. In addition, such parameters can be used in later experiments to measure defense mechanisms and the modulation of shrimp response to pathogenic agents and environmental stress.

The coagulant response in sepsis and inflammation

Critically ill patients often have systemic activation of both inflammation and coagulation. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may have major consequences for the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by tissue factor pathway inhibitor. Simultaneously, endothelial-bound anticoagulant mechanisms, in particular the protein C system and the antithrombin system, are shut-off by pro-inflammatory cytokines. Modulation of inflammatory activity by activation of coagulation also occurs by various mechanisms. Activated coagulation proteases, such as the tissue factor-factor VIIa complex, factor Xa and thrombin can bind to protease-activated receptors on various cells and the ensuing intracellular signaling leads to increased production of pro-inflammatory cytokines and chemokines. Physiological anticoagulants can modulate inflammatory activity as well. Increasing knowledge on the various mechanisms underlying activation of inflammation and coagulation may lead to better (adjunctive) management strategies in critically ill patients.

Effects of physiological anticoagulants on vascular cells

Effects of physiological anticoagulants on vascular cells

Review: New anticoagulants: a story of promise and disappointment

The anticoagulant drugs which are available currently — coumarins and heparins — are reasonably effective but are insufficiently specific and often inconvenient to manage. An improved understanding of the physiology of blood coagulation and its control mechanisms has led to the identification of target enzymes for novel, specific and potentially safer antithrombotics. These targets include the pivotal coagulation enzyme thrombin as well as other enzymes and co-factors within the tissue factor dependent coagulation pathway. In addition, analogues of physiological anticoagulants hold promise as therapeutic agents. It is likely that the range of drugs available for the management of thrombosis will expand over the next decade. There is the very real possibility of the introduction of orally active agents which may be used in fixed dosage regimens with no requirement for laboratory monitoring.

Activated protein C prevents inflammation yet stimulates angiogenesis to promote cutaneous wound healing

Activated protein C (APC) is a serine protease that plays a central role in physiological anticoagulation, and has more recently been shown to be a potent anti-inflammatory mediator. Using cultured human cells, we show here that APC up-regulates the angiogenic promoters matrix metalloproteinase-2 in skin fibroblasts and umbilical vein endothelial cells, vascular endothelial growth factor in keratinocytes and fibroblasts, and monocyte chemoattractant protein-1 in fibroblasts. In the chick embryo chorioallantoic membrane assay, APC promoted the granulation/remodeling phases of wound healing by markedly stimulating angiogenesis as well as promoting reepithelialization. In a full-thickness rat skin-healing model, a single topical application of APC enhanced wound healing compared to saline control. APC-treated wounds had markedly more blood vessels on day 7 and a significantly lower infiltration of neutrophils at days 4 and 7. The broad spectrum matrix metallo-proteinase, GM6001, prevented the ability of APC to promote wound healing. In summary, our results show that APC promotes cutaneous wound healing via a complex mechanism involving stimulation of angiogenesis and inhibition of inflammation. These unique properties of APC make it an attractive therapeutic agent to promote the healing of chronic wounds.

Haemostatic changes in pregnancy

In normal pregnancy, there is a marked increase in the procoagulant activity in maternal blood characterized by elevation of factors VII, X, VIII, fibrinogen and von Willebrand factor, which is maximal around term. This is associated with an increase in prothrombin fragments (PF1+2) and thrombin–antithrombin complexes. There is a decrease in physiological anticoagulants manifested by a significant reduction in protein S activity and by acquired activated protein C (APC) resistance. The overall fibrinolytic activity is impaired during pregnancy, but returns rapidly to normal following delivery. This is largely due to placental derived plasminogen activator inhibitor type 2 (PAI-2), which is present in substantial quantities during pregnancy. D-dimer, a specific marker of fibrinolysis resulting from breakdown of cross-linked fibrin polymer by plasmin, increases as pregnancy progresses. Overall, there is a 4- to 10-fold increased thrombotic risk throughout gestation and the postpartum period. Local haemostasis at the placental throphoblast level is characterized by increased tissue factor (TF) expression and low expression of the inhibitor TFPI. Microparticles derived from maternal endothelial cells and platelets, and from placental throphoblasts may contribute to the procoagulant effect. Local anticoagulant mechanisms on placental throphoblasts are important for counterbalance of the procoagulant milieu. Disruption of anticoagulant mechanisms, for example, autoantibodies, to annexin V may increase pregnancy complications in patients with antiphospholipid antibodies (APLA).

Increased rate of renal transplant failure in patients with the G20210A mutation of the prothrombin gene

In patients with thrombophilia caused by reduced physiological anticoagulation, renal transplant failure occurs more frequently. Previous studies showed the importance of the protein C system, a physiological anticoagulatory pathway that inhibits thrombus formation. However, excess activation of the hemostatic system also may result in thrombosis. The G20210A mutation in the prothrombin gene is such a prothrombotic risk factor that results in increased thrombus formation because of elevated factor II levels in plasma. We analyzed graft function in 270 consecutive patients who received 311 renal transplants. The presence of a normal or mutated prothrombin allele was determined by polymerase chain reaction amplification and restriction fragment length polymorphism analysis of genomic DNA. Demographic data were extracted from hospital records. Graft survival was calculated for patients with and without the G20210A mutation. We identified 9 patients heterozygous for the G20210A mutation in the prothrombin gene who had received a total of 12 renal transplants. Of these 12 transplants, 2 grafts were lost within the first year. Median graft survival for patients heterozygous for the 20210A allele was 65.9 months (range, 0 to 101 months) compared with 149 months (range, 0 to 237 months) for patients homozygous for the normal 20210 G allele (P = 0.02). The G20210A mutation represented a 2.95-fold (95% confidence interval, 1.03 to 8.46) increase in risk for graft loss. Only 1 patient with this mutation achieved graft function exceeding 101 months. The G20210A mutation of the prothrombin gene is an independent risk factor for graft failure. © 2001 by the National Kidney Foundation, Inc.

Prevalence of genetic mutations that predispose to thrombophilia in a Greek Cypriot population.

Several hereditary disorders, particularly those affecting the physiological anticoagulation systems, have been well established as risk factors for venous thromboembolism. In the present study, we investigated the prevalence of the following thrombogenic mutations in a Greek-Cypriot population: the G1691 factor V Leiden mutation, the G20210A mutation in the prothrombin gene, and the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR). All three variants have been documented to be significant risk factors for various cardiovascular conditions. Ninety unrelated subjects were screened. For the Leiden mutation, 11 subjects (12.2%) were heterozygous and one (1.1%) was homozygous. Seven subjects (7.8%) were heterozygous for the G20210A variant in prothrombin; no homozygotes were identified. The C677T mutation in MTHFR was found in 40 individuals in the heterozygous state (44.4%), and in 16 individuals in the homozygous state (17.8%). These data demonstrate that Greek-Cypriots have an increased frequency of thrombogenic mutations, and suggest that screening for these mutations should be seriously considered, especially when surgery or pregnancy is planned. This is the first study for the frequency of mutations in risk factors that predispose to thrombophilia on the island of Cyprus.