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PubMed1976

Activation and consumption of Hageman factor in the anaphylactic shock of the rat.

In the early stages of anaphylactic shock of rats pretreated with Bordetella pertussis vaccine, a prompt and parallel activation of the factor XIIa-dependent intrinsic coagulation, kinin generation, and fibrinolytic acticity was observed. The coagulation studies, the similarity of anaphylactic results with those produced by a single injection of ellagic acid, and the effective inhibition of the anaphylactic and the ellagic acid-induced activation of these pathways by lysozyme all suggest that factor XII itself becomes activated in rat anaphylaxis. As the reaction proceeded, considerable anticoagulant activities emerged, but the bradykinin and the plasminogen activator levels even further increased. During the first 10 min of anaphylactic shock, factor XII was partly consumed and this was prevented by epsilon-aminocaproic acid infusion. The results show that in pathological conditions such as anaphylaxis there is an intimate in vivo interaction among the three factor XIIa-dependent pathways.

Aminocaproates↗

PubMed1993

[Prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complex(TAT) and thrombophilia parameters in orally anticoagulated patients with inferior vena cava filters].

Prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin-III-complex (TAT) levels were compared in 31 orally anticoagulated patients with inferior vena caval filters and a control group of 31 orally anticoagulated patients without caval filters and the incidence of markers of thrombophilia (deficiency of antithrombin-III, protein C, protein S and factor XII, presence of lupus anticoagulants) was determined. 8 of 31 patients (26%) from the group of caval filter carriers showed markers of thrombophilia (3 protein S deficiencies, 1 protein C deficiency, 2 factor XII deficiencies and 2 patients with lupus anticoagulants). In all orally anticoagulated patients a significant interdependence (p < 0.05) between F1 + 2- and TAT-levels and intensity (INR) of the oral anticoagulation could be observed. Comparison of F1 + 2- and TAT-levels of caval filter carriers and controls revealed no significant difference which leads to the conclusion that inferior vena caval filters do not induce detectable systemic activation of prothrombin under adequate oral anticoagulation therapy.

Administration, Oral↗

PubMed1987

A coherent biochemical basis for increased reactivity to contrast material in allergic patients: a novel concept.

Bradykinin, the end product of activation of the plasma contact system, may play a significant role in reactions to contrast material and in other forms of anaphylactoid and anaphylactic responses to drugs or antigens. Activation of factor XII initiates activity in the plasma contact system, and we have identified factors (negatively charged surfaces) present in elevated concentrations in the plasma of patients who are asthmatic or allergic that can "prime" their plasma for the initiation and/or potentiation of factor XII activation. In other studies, we have shown that persons who react to contrast material and persons who are asthmatic or allergic share both a potential for accelerated contact system activity and evidence of an increased mean concentration of low-level contact system products. Recently, we have found that contrast media can inhibit angiotensin-converting enzyme, the substance that hydrolyzes bradykinin and limits its systemic effects. Thus, a number of factors suggest that it is the potential for increased production of bradykinin in persons who are allergic or asthmatic that may account for the greatly increased susceptibility of these patients to contrast material. This susceptibility may be critically triggered by the contrast media-induced inhibition of angiotensin converting enzyme. In view of these findings, the possibility exists that most, if not all, significant reactions to contrast material require an underlying allergic diathesis that may, or may not, be apparent by history and conventional diagnostic testing.

Anaphylaxis↗

PubMed1988

Activation of the contact system of plasma proteolysis in the adult respiratory distress syndrome.

Adult respiratory distress syndrome (ARDS) is a complex pulmonary clinicopathologic condition associated with pulmonary endothelial injury and blood coagulation activation. In patients with ARDS from all causes, factor VII levels were significantly reduced. Patients with ARDS caused by sepsis had more evidence of intravascular coagulation and fibrinolysis than did patients with trauma-related ARDS by having significantly (p less than or equal to 0.05) increased prothrombin times, activated partial thromboplastin times, and fibrin degradation products, and decreased antithrombin III concentration. We sought to determine whether the proteins of the contact system of plasma proteolysis (factor XII, prekallikrein, high molecular weight kininogen, and C1 inhibitor) were also activated after acute lung injury. Patients with ARDS caused by either trauma or sepsis had significantly (p less than or equal to 0.01) reduced factor XII levels, high molecular weight kininogen functional activity, prekallikrein activity, and prekallikrein antigen levels compared with controls. In both the sepsis-related and trauma-related ARDS groups, C1 inhibitor activity was significantly reduced but C1 inhibitor antigen levels were significantly elevated from control. These findings showed that the proteins of the contact system were more extensively activated in ARDS than were the proteins that contribute to later reactions in intravascular coagulation and fibrinolysis. Activation of the contact system proteins could be the result of endothelial injury occurring as part of ARDS. Intravascular coagulation and fibrinolysis in patients with ARDS also arise from components independent from contact system activation.

Blood Coagulation↗

PubMed2001

Impaired fibrinolysis and increased fibrinogen levels in South Asian subjects.

The potential role of haemostatic risk markers is largely unexplored in South Asians, who have increased morbidity and mortality from cardiovascular disease and an increased prevalence of insulin resistance. To investigate differences in thrombotic risk markers between South Asian and White populations, 42 Asian and 50 White males and 96 Asian and 80 White females, clinically free from vascular disease, were recruited. Venous blood samples were taken for measures of haemostasis and determination of blood lipids. South Asian females showed lower fasting blood glucose than White females (4.6 vs. 4.8 mmol/l, P<0.008). In the South Asian population, total cholesterol was lower in females, with a similar trend in males (females 5.0 vs. 5.5 mmol/l, P<0.001; males 5.1 vs. WM 5.5 mmol/l, P=0.09), but no difference in triglyceride levels. South Asian subjects of both genders had markedly higher levels of fibrinogen (females 3.3 vs. 2.8 mg/dl, P<0.0005; males 3.0 vs. 2.5 mg/dl P<0.002) and PAI-1 activity (females 14.6 vs. 8.7 ng/ml, P<0.0005, males 21.3 vs. 12.2 ng/ml, ) P<0.0005). Factor VII:C was lower in both South Asian groups (females 110.9 vs. 122.4%, P<0.005; males 103.3 vs. 125%, P<0.0005). Factor XII was lower in South Asian females and there were no differences in Factor XII levels in male populations. These results suggest that elevated PAI-1 and fibrinogen in Asians of both genders may contribute to the increased vascular risk experienced in this population; however, the role of dyslipidaemia and Factor VII are not clear in these processes.

Adult↗

PubMed1994

Stearic acid, clotting, and thrombosis.

Stearic acid causes hypercoagulability of the blood by activation of factor XII and by aggregation of blood platelets. Injection of unbound stearic acid (sodium salt) into the systemic circulation of dogs was followed by massive generalized thrombosis and sudden death. Similar infusions into birds, which are deficient in factor XII, did not cause hypercoagulability or thrombosis. The effects of the long-chain saturated fatty acids could be prevented by using albumin to bind the stearic acid at a molar ratio of free fatty acid (FFA) to albumin of < 2. The major issue is whether eating foods rich in stearic acid can cause a thrombogenic effect. We have no experimental evidence to support this concept. If a thrombogenic effect of long-chain saturated fatty acids exists in humans, it is most likely to occur as an aberration of fatty acid transport in which the FFA-albumin molar ratio exceeds 2 either as a result of very high plasma FFA concentrations from lipid mobilization or a low concentration of albumin in the blood as found in disease states such as the nephrotic syndrome.

Animals↗

PubMed1995

Assembly and activation of the intrinsic fibrinolytic pathway on the surface of human endothelial cells in culture.

Factor XII has long been implicated in the intrinsic pathway of fibrinolysis, but the mechanism by which it triggers plasminogen activation and targets fibrinolysis has not been established. In the present study, the assembly and function of activated Factor XII (F.XIIa), prourokinase (pro-u-PA), high molecular weight kininogen (H-kininogen), and prekallikrein on human umbilical vein endothelial cells (HUVEC) was investigated. 125I-prekallikrein was shown to bind to HUVEC via receptor-bound H-kininogen in the presence of 50 microM ZnCl2. After the addition of F.XIIa, 78% of the 125I-prekallikrein initially bound to HUVEC was converted to 125I-kallikrein. However, only 6% of the HUVEC-bound 125I-pro-u-PA was thereby activated. This discrepancy was shown to be related to rapid dissociation (> 50% within 15 min) of prekallikrein/kallikrein, but not pro-u-PA, from HUVEC. Increasing the level of cell-bound kallikrein increased the portion of cell-bound pro-u-PA activated, indicating that their co-localization was important for this pathway. Finally, F.XIIa was shown to trigger plasminogen activation on HUVEC via this pathway. This assembly of reactants on the endothelium suggests a mechanism whereby local fibrinolysis may be triggered by blood coagulation.

Blood Coagulation↗

PubMed1995

The crystal structure of the catalytic domain of human urokinase-type plasminogen activator.

BACKGROUND: Urokinase-type plasminogen activator (u-PA) promotes fibrinolysis by catalyzing the conversion of plasminogen to the active protease plasmin via the cleavage of a peptide bond. When localized to the external cell surface it contributes to tissue remodelling and cellular migration; inhibition of its activity impedes the spread of cancer. u-PA has three domains: an N-terminal receptor-binding growth factor domain, a central kringle domain and a C-terminal catalytic protease domain. The biological roles of the fibrinolytic enzymes render them therapeutic targets, however, until now no structure of the protease domain has been available. Solution of the structure of the u-PA serine protease was undertaken to provide such data. RESULTS: The crystal structure of the catalytic domain of recombinant, non-glycosylated human u-PA, complexed with the inhibitor Glu-Gly-Arg chloromethyl ketone (EGRcmk), has been determined at a nominal resolution of 2.5 A and refined to a crystallographic R-factor of 22.4% on all data (20.4% on data > 3 sigma). The enzyme has the expected topology of a trypsin-like serine protease. CONCLUSIONS: The enzyme has an S1 specificity pocket similar to that of trypsin, a restricted, less accessible, hydrophobic S2 pocket and a solvent-accessible S3 pocket which is capable of accommodating a wide range of residues. The EGRcmk inhibitor binds covalently at the active site to form a tetrahedral hemiketal structure. Although the overall structure is similar to that of homologous serine proteases, at six positions insertions of extra residues in loop regions create unique surface areas. One of these loop regions is highly mobile despite being anchored by the disulphide bridge which is characteristic of a small subset of serine proteases namely tissuetype plasminogen activator, Factor XII and Complement Factor I.

Amino Acid Sequence↗

PubMed2002

Acquired inhibitors to coagulation factors in patients with gastrointestinal diseases.

OBJECTIVES: To study the frequency and specificity of acquired coagulation inhibitors in inflammatory and malignant gastrointestinal diseases. METHODS: In a 10-year period, 511 patients from the island of Crete in Greece were studied, 302 with ulcerative colitis, 112 with Crohn's disease, 82 with gastrointestinal carcinoma and 15 with gastrointestinal lymphoma. Prothrombin time and activated partial thromboplastin time were measured by routine methods. When prothrombin time and/or activated partial thromboplastin time were found to be prolonged, mixture experiments with 25%, 50% and 75% pooled normal human plasma were performed. If clotting times were inadequately corrected, the presence of an acquired inhibitor against a coagulation factor was suggested. Specific coagulation factor assays were then performed with deficient plasmas. RESULTS: Fifteen patients acquired inhibitors to the following coagulation factors within the 10-year observation period: factor IX (four patients); factor X (three patients); factor XII (three patients); factor VIII (two patients); factor XI (two patients); and factor V (one patient). The activity of the above factors varied from < 1% to 10%. Five patients with ulcerative colitis, six with Crohn's disease, two with gastrointestinal lymphoma and two with gastrointestinal carcinoma developed an inhibitor. Only one patient with factor VIII inhibitor presented with severe bleeding and was treated with recombinant human activated factor VII, while the others had no complications. Remission was obtained in all patients after immunosuppressive therapy, chemotherapy or tumour resection. CONCLUSION: An increased incidence of coagulation factor inhibitors was found in patients with gastrointestinal inflammatory and malignant diseases compared to the healthy population. In addition, an increased incidence of these inhibitors was also found in the common population of Crete compared to that found in other areas.

Adolescent↗

PubMed1979

The role of endothelial cells and subendothelial components in the initiation of blood coagulation.

The effect of collagen on isolated platelets, platelet-rich plasma and whole blood has been studied. Collagen failed to generate factor XIa-like activity in mixtures of isolated platelets, collagen and Ca++. Moreover, collagen added to whole blood or platelet-rich plasma containing 125I-factor IX and Ca++, also failed to form cleaved (activated) factor IX. In preliminary studies, lysed endothelial cells were found to enhance the formation of factor Xa and thrombin and to induce cleavage of 125I-factor IX in normal plasma, factor XII and factor-XI-deficient plasma even in the presence of antibody to tissue factor.

Blood Coagulation↗

PubMed1994

Factor XI: purification from porcine plasma by affinity chromatography and some properties of factor XI and activated factor XI.

Porcine factor XI and activated factor XI were purified by the introduction of affinity chromatography on high molecular mass kininogen. On the affinity chromatography, it was observed that high affinity exists between porcine factor XI and high molecular mass kininogen. In the preparation, however, factor XII, plasma prekallikrein and high molecular mass kininogen were not detected. The factor XI forms a dimer, and is a heterogeneous molecule, judging from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Substrate specificity of activated factor XI and inhibition profile of activated factor XI against proteinase inhibitors were investigated by comparison with those of bovine and human activated factor XI. From these results, the properties of porcine activated factor XI show great similarities with those of bovine and human activated factor XI.

Amino Acid Sequence↗

PubMed1979

[Hemorrhagic diathesis in patients with malignant neoplasms (author's transl)].

Clotting analysis in 30 patients with bleeding complications in malignant hematological diseases revealed the following troubles: The global tests, Quick's index and partial thromboplastin time markedly differed from normal. Activity of clotting factors revealed hypo- or hyperfibrinogenemia, disturbances of the prothrombin complex (factors II, VII, IX and X), decrease of factors V, VIII, XII. Factor XI (= PTA) was not diminished in any case. Regarding the fibrin-stabilizing factor (factor XIII), its activity was significantly decreased in 30 patients with solid tumors and in 30 patients with hemoblastoses. Faulty clotting balance was characterized by hyperfibrinolysis or disseminated intravascular coagulation (DIC) accompanied by reactive hyperfibrinolysis. About one quarter of the patients with malignant disturbances of the hematopoetic system demonstrated (mostly amegacaryocyte) thrombocytopenia. Finally, treatment of bleeding complications in malignant neoplastic diseases is pointed out.

Blood Coagulation Tests↗

PubMed2002

[Unsuspected prolonged activated partial thromboplastin time in emergency surgery. Diagnostic and therapeutic guide].

Systematic complementary testing for asymptomatic patients before surgery yields an unexpectedly high percentage of anomalous results. Such results rarely affect perioperative management of the patient but may lead to unnecessary delays, which are potentially of great importance in emergency surgery. A 55-year-old woman with a clinical diagnosis of acute appendicitis was seen to have a prolonged activated partial thromboplastin time (APTT) of 1.94 before surgery. The patient's history did not suggest a coagulation disorder was likely, and when mixing normal and problem plasma failed to correct the APTT, we suspected an unspecified circulating anticoagulant was present. Surgery was delayed no further and no measures were taken. No excessive bleeding occurred during surgery or postoperative recovery. The main possible diagnoses for a women with unforeseen prolonged APTT are the presence of an unspecified circulating anticoagulant, factor XI or factor XII deficiency, or factor VIII deficiency associated with von Willebrand disease. Focusing on detecting a coagulation disorder while taking a patient's history and performing a simple laboratory test (mixing normal and problem plasma) can be useful for orienting management in emergency surgery.

Blood Coagulation Disorders↗

PubMed1992

Activation of the contact system in lethal hypotensive bacteremia in a baboon model.

The hypotension in septicemia is believed to be mediated by the combined action of many mediators including cytokines, prostaglandins, and complement components. To evaluate the contribution of the contact/kinin-forming system to hypotension, the authors used an established experimental baboon model of bacteremia in which two concentrations of Escherichia Coli (E. coli) were used to produce lethal and nonlethal hypotension. The lethal group (n = 5) developed irreversible hypotension that significantly correlated with the decline in levels of high molecular weight kininogen (HK) and an increase in alpha 2 macroglobulin-kallikrein complexes (alpha 2M-kal). The nonlethal group (n = 9) experienced reversible hypotension, a less striking decline in HK, and only slight elevation in alpha 2M-kal. No significant changes were found in levels of factor XII, prekallikrein, and factor XI in either group. A significant change in the contact system, which reflects the fatal outcome, is the rise in alpha 2M-kal. This study suggests that irreversible hypotension correlates with prolonged activation of the contact system.

Animals↗

PubMed1990

Notes on clotting in a Burmese python (Python molurus bivittatus).

Studies of the clotting mechanisms in the plasma of a Burmese python (Python molurus bivittatus) confirm earlier information that both extrinsic and intrinsic pathways of thrombin formation participate in reptilian hemostasis. Plasma fibrinogen was present at a concentration comparable to that in human plasma. Other assays were hampered by the need to use nonreptilian reagents. The activated partial thromboplastin time was shorter than was that of human plasma, thus implying the presence of prothrombin in python plasma; however, this protein could be demonstrated only in trace amounts. Similarly, only small amounts of Hageman factor (factor XII) and antihemophilic factor (factor VIII) were detected, and none of plasma prekallikrein, high-molecular-weight kininogen, and Christmas factor (factor IX). The prothrombin time was slower than that of human plasma. Factor VII was not detected, but both proaccelerin (factor V) and Stuart factor (factor X) were present. Python plasma inhibited bovine thrombin and human plasmin, but it was deficient in fibrinolytic capacity.

Animals↗

PubMed1977

Oxygen-induced consumptive coagulopathy and its enhancement by lead acetate.

The exposure of rats to 100% oxygen at 1 atmosphere leads to a prolongation of prothrombin times and activated partial thromboplastin times. This development is associated with a consumption of factor XII, VIII, and VII activities and with the appearance of fibrin monomers and fibrinogen degradation products. Lead acetate enhances all oxygen-induced changes of the coagulation systems drastically. The O2 survival time of chicks which are naturally deficient in factor XII is greatly increased over that of rats and is not affected by lead acetate. Oxygen survival times of rats suffering from chronic respiratory disease (CRD) are also significantly increased when compared with normal rats. It appears that consumptive coagulopathy and disseminated intravascular coagulation are early events in oxygen exposure, and that their development is accelerated by lead ions.

Animals↗

PubMed1996

Plant serine proteinase inhibitors. Structure and biochemical applications on plasma kallikrein and related enzymes.

The action of two Bowman-Birk and several plant Kunitz-type inhibitors were studied on trypsin, chymotrypsin, plasma kallikrein and factor XII. The primary structure of some of them was completely defined. The results showed that the Bowman-Birk type inhibitors, although potent inhibitors for trypsin (Ki in the range of 1-2 nM), are not able to inhibit plasma kallikrein. Factor XII (Ki = 1.4 microM) and chymotrypsin (Ki = 5.0 nM) are inhibited by Torresea cearensis trypsin inhibitor (TcTI) but not by Dioclea glabra trypsin inhibitor (DgTI). Both inhibitors reactive site regions are highly homologous, and the amino acid residues in P1 position are the same, Lys and His; major differences are in the charge of the C-terminal portion of the molecules. The studied Kunitz-type inhibitors were all able to inhibit plasma kallikrein (Ki between 4 and 80 nM), with the exception of Schizolobium parahyba chymotrypsin inhibitor (SpCI), that is specific for chymotrypsin. All Kunitz-type inhibitors inactivate chymotrypsin, but with a dissociation constant in the range of 0.1 to 0.6 microM. Factor XIIf is inhibited with Ki in the range of 0.1 microM. Bauhinia bauhinioides trypsin inhibitor (BbTI) did not promote factor XIIf inhibition. The Kunitz-type inhibitors are a highly homologous, sharing 60% identity in the N-terminal portion of the loop containing the reactive site, and 28.6% identity in the C-terminal portion of the same loop.

Amino Acid Sequence↗

PubMed2001

Hydrophilic hybrid IPNs of segmented polyurethanes and copolymers of vinylpyrrolidone for applications in medicine.

The preparation and biocompatibility properties of thermoplastic apparent interpenetrating polymer networks (T-IPNs) of a segmented polyurethaneurea, Biospan (BS), and vinylpyrrolidone-dimethylacrylamide (VP-DMAm) copolymers, are described. The biological interaction between the obtained materials and blood was studied by in vitro methods. The addition of the VP-DMAm copolymers to form T-IPNs with BS substantially increased the equilibrium water uptake and water diffusion coefficients. Investigation of the proteins adsorption, platelet adhesion, thrombus formation and factor XII activation is presented. Investigations of the proteins adsorption of the BS/VP-DMAm T-IPNs surfaces show that the segmented polyurethane (BS) containing VP-DMAm copolymers with higher VP content adsorb more albumin than fibrinogen and gamma-globulin. The platelets adhesion, thrombus formation and factor XII activation are effectively suppressed with respect to the segmented polyurethane when VP-DMAm copolymers with high VP contents are incorporated into BS as T-IPNs.

Adsorption↗