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PubMed1995

Plasmin-mediated activation of contact system in response to pharmacological thrombolysis.

BACKGROUND: Thrombin activity increases in patients treated with coronary thrombolysis for acute myocardial infarction, but the mechanisms are not well defined. We have shown that thrombin activity increases in plasma and whole blood incubated with plasminogen activators and appears to be plasmin mediated and dependent on activity of the factor VIIIa/IXa complex. METHODS AND RESULTS: In the present study, increases in thrombin activity induced by incubation of recalcified citrated plasma with 0.16 to 0.5 mumol/L plasmin at 37 degrees C were markedly attenuated in recalcified citrated plasma deficient in factors XI or XII, prekallikrein, or high molecular weight kininogen, as well as in plasma incubated with plasmin in the presence of 3.5 mumol/L corn trypsin inhibitor, a specific factor XIIa inhibitor. Increases in thrombin activity also occurred in nonanticoagulated whole blood incubated with pharmacological concentrations of plasminogen activators and were markedly attenuated in the presence of corn trypsin inhibitor. Plasmin-mediated (0.25 mumol/L) activation of purified factor XII occurred in 0.05 mol/L Tris-HCl and 0.012 mol/L NaCl (pH 7.8) at 37 degrees C, resulting in equimolar quantities of two fragments that corresponded to cleavage of factor XII at Arg353-Val354, the site involved in kallikrein-mediated activation of factor XII, and cleavage at Lys346-Ser347, an apparently novel site of plasmin-mediated hydrolysis of factor XII. Contact activation was also demonstrated in plasma samples from patients after treatment with fibrinolytic agents for myocardial infarction, by demonstrating cleavage of high molecular weight kininogen from its one-chain to its two-chain form by ligand blotting with 125I-prekallikrein. CONCLUSIONS: Plasmin-mediated activation of the contact system of coagulation appears to account, at least in part, for increases in procoagulant activity in patients treated with fibrinolytic agents. It may also explain hypotension, by release of bradykinin from high molecular weight kininogen, and complement activation, by activated factor XII, that has been demonstrated in these patients.

Biomarkers↗
PubMed1963

[PLASMA-KININS].

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Bradykinin↗
PubMed1982

Plasma kallikrein-mediated activation of the renin-angiotensin system does not require prior acidification of prorenin.

Activation of prorenin in the neutral phase after pH 3.3 dialysis of human plasma depends on clotting factor XII-initiated prekallikrein to kallikrein conversion. Acid dialysis may be necessary for destroying kallikrein inhibitors or rendering prorenin susceptible to attack by kallikrein. If the latter possibility proves true, it is difficult to see how the factor XII-kallikrein pathway could activate prorenin in vivo. Plasma prorenin was therefore separated from active renin and from the protease inhibitors alpha 2-macroglobulin, C1-inactivator, alpha 1-antitrypsin, inter-alpha-trypsin inhibitor, and antithrombin III by gel filtration on Sephadex G-100 and affinity chromatography on Blue Sepharose CL-6B at neutral pH. The resulting prorenin preparation could be activated at pH 7.5 by highly purified human plasma kallikrein, which was prepared from prekallikrein by activation with active factor XII fragment beta-factor XII a. Activation proceeded at 4 and 37 C at a kallikrein concentration of 2 micrograms/ml, which is approximately 5% of the prekallikrein concentration in normal plasma. It appears that an acid-induced conformational change of the prorenin molecule is not required for its activation by plasma kallikrein.

Angiotensin I↗
PubMed1982

Role of charged groups in factor XI/XIa activity.

To elucidate the role of charged groups in expression of factor XI coagulant activity, the charged groups of purified human blood coagulation factor XI/XIa containing 125I-XI/XIa were derivatized: free amino groups by succinylation, guanido groups of arginine by reaction with phenylglyoxal hydrate, and free carboxyl groups by reaction with ethylenediamine. The modified proteins were tested for: 1) ability to adsorb to glass, 2) ability to be cleaved by trypsin or factor XII-high molecular weight kininogen, 3) coagulant activity. The amino group-modified factor XI had a significantly decreased ability to bind to glass; modification of arginine or carboxyl groups did not affect adsorption. Trypsin cleaved factor XI with modified free amino, guanido, or carboxyl groups. Factor XII-high molecular weight kininogen could cleave only the arginine-modified factor XI. Amino group-modified factor XI and carboxyl group-modified factor XI lost all their factor XI assay activity, whereas arginine-modified factor XI retained 50% of the original activity. Amino group-modified factor XI could not be activated by trypsin, but arginine-modified and carboxyl group-modified factor XI could be activated by trypsin to 50% of the original activity. Succinylation of the amino groups of factor XIa destroyed all its factor XIa activity. Arginine-modified and carboxyl group-modified factor XIa retained 50% of their factor XIa activity. We conclude that epsilon-amino groups are essential for adsorption; activation by factor XII-high molecular weight kininogen requires free amino and carboxyl but not guanido groups; free amino, carboxyl, and guanido groups in factor XIa all appear to be critical for interaction of factor XIa with factor IX.

Blood Coagulation↗
PubMed1981

Investigations on radiosensitive and radioresistant populations of Drosophila melanogaster. XII. The resistance factor rar-3: stage specificity.

In earlier studies the recessive genetic factor rar-3 (3-49.8) of Drosophila melanogaster had been found to reduce the sensitivity of immature oocytes to the mutagenic action of X-rays. The present work was devoted to an extension of these studies to other germ-cell stages in both male and female and also somatic cells. The results show that, in the female, the effects of rar-3 are manifest in all germ-cell stages including gonia and nurse cells but not in mature oocytes. In the male germ-cell stages, rar-3 was without any measurable effect; maternal-effect studies were likewise negative. Somatic tissues were also unaffected. Furthermore, rar-3 was apparently not active in larval oogonia. It is therefore concluded that the activity of rar-3 is switched on in oogonia during puparium formation or metamorphosis and persists until before the formation of the mature oocyte.

Animals↗
PubMed2004

Generation of active fragments from human zymogens in the bradykinin-generating cascade by extracellular proteases from Vibrio vulnificus and V. parahaemolyticus.

Vibrio vulnificus is an opportunistic human pathogen causing septicemia, and the infection is characterized by formation of the edematous skin lesions on limbs. This pathogenic species secretes a thermolysin-like metalloprotease as a virulence determinant. The metalloprotease was confirmed to activate human factor XII-plasma kallikrein-kinin cascade that results in liberation of bradykinin, a chemical mediator enhancing the vascular permeability, from high-molecular weight kininogen. Namely, the metalloprotease showed to generate active fragments by cleavage of Arg-Ile, Arg-Val or Gly-Leu peptide bond in human zymogens (plasma prekallikrein and factor XII). In spite of induction of the sufficient vascular permeability-enhancing and edema-forming reaction in the guinea pig model, a serine protease from V. parahaemolyticus, a human pathogen causing primarily watery diarrhea, showed far less ability to activate and to cleave the human zymogens. These results in part may explain why only V. vulnificus often causes serious edematous skin damages in humans.

Amino Acid Sequence↗
PubMed1990

Purification and characterization of a plasma factor which cleaves single-chain form of t-PA and u-PA.

Low molecular weight heparin (LMW-heparin) enhanced the amidolytic activity of plasma when the chromogenic substrate, H-D-Ile-Pro-Arg-pNA (S-2288), was used. The amidolytic activity increased in a time-dependent manner as the LMW-heparin concentration increased and reached its peak at around 15 mu/ml. Factor XII-deficient plasma increased the S-2288 amidolytic activity by LMW-heparin. In order to clarify the mechanism of the heparin-induced enhancement of the amidolytic activity, a plasma factor was purified. The plasma factor was obtained from human normal plasma by ammonium sulfate fractionation, followed by successive column chromatography with heparin-Sepharose, zinc chelate-Sepharose, aprotinin-Sepharose and protein A-Sepharose. The plasma factor so purified revealed a major band (88% of total protein) at 80 kD with several minor bands on analysis by SDS-PAGE. The plasma factor exhibited an intrinsic amidolytic activity, which was enhanced by heparin. The plasma factor further enhanced the amidolytic activity of sct-PA and scu-PA, the enhancement of which was of much greater degree than that for LMW-heparin. However, when the two-chain form of t-PA or u-PA was reacted with the plasma factor and LMW-heparin, no enhancement of the amidolytic activity of these enzymes was observed. The plasma factor cleaved a peptide bond of sct-PA and scu-PA and induced a structural change from a single-chain to a two-chain form. The amidolytic activity of the plasma factor was not inhibited by anti-t-PA IgG, anti-u-PA IgG, anti-plasminogen IgG, anti-factor XII IgG or anti-plasma prekallikrein IgG. These findings suggest an important role for the plasma factor in the activation of sct-PA and scu-PA in heparin-dependent fibrinolysis.

Amides↗
PubMed1986

The activation of pro-urokinase by plasma kallikrein and its inactivation by thrombin.

Plasma kallikrein was found to be a good activator of pro-urokinase, the inactive zymogen form of urokinase. The complete activation of pro-urokinase by plasma kallikrein was obtained in 2 h with an enzyme/substrate weight ratio of 1/30. The rate of activation of pro-urokinase by plasma kallikrein was comparable to that catalyzed by plasmin and trypsin. The rate of activation of pro-urokinase by factor XIIa was approximately one-seventh of that by plasma kallikrein. The activation of the zymogen was due to the cleavage of a single internal peptide bond, resulting in the conversion of a single chain pro-urokinase (Mr = 55,000) into two-chain urokinase (Mr = 33,000 and 22,000), and these two chains were linked by a disulfide bond(s). These results indicate an important role of plasma kallikrein for the activation of pro-urokinase in the factor XII-dependent intrinsic pathway of fibrinolysis. Thrombin also converted pro-urokinase to a two-chain form that was not activatable by plasmin, plasma kallikrein, and factor XIIa. Thrombin specifically cleaved the Arg 156-Phe 157 bond which is located 2 residues prior to the activation site of Lys 158-Ile 159.

Amino Acid Sequence↗
PubMed1999

Systemic lupus erythematosus presenting with haemorrhagic manifestation.

A 26-year-old female presented with an episode of severe mucus membrane bleeding. Investigations revealed prolonged prothrombin time (PT), and partial thromboplastin time (PTT), normal thrombin time (TT) and reptilase time, thrombocytopenia, a positive test for lupus anticoagulant (LA), as well as anti-cardiolipin antibodies (ACL). A toxicology screen for toxic drugs and coumadin was negative. Coagulation factor assays revealed low levels for factor II and XII. Low level inhibitor to factor II was demonstrated. Patient had a negative VDRL test and positive anti-nuclear antibodies (ANA). The diagnosis of acquired hypoprothrombinaemia secondary to circulating inhibitor induced by LA was made, and then the patient was started on prednisone, which led to cessation of the bleeding and normalization of PT and PTT, as well as an increase of factor II and factor XII levels. A few months later, the patient developed arthralgia and alopecia, and antibodies against double-stranded DNA were detected, and the diagnosis of systemic lupus erythematosis (SLE) was confirmed. The patient continued to have mild prolongation of PT and PTT while on a low dose of prednisone, but she had no bleeding symptoms. A computed tomography scan of the brain was carried out for unexplained central nervous system (CNS) symptoms, and it revealed mild hydrocephalus, which was thought to be part of the CNS manifestations of SLE. It was concluded that patients with SLE may present with haemostatic defects that are a result of either platelet-related causes (quantitative or qualitative) or coagulation factor deficiency secondary to circulating inhibitor, or both, in the absence of other features of SLE which may appear later.

Adult↗
PubMed1982

Role of intrinsic inhibitors in acid-activation of inactive plasma renin (prorenin).

Inactive plasma renin is converted into an active form of renin during dialysis of plasma against a pH 3.3-buffer. This form of renin is inactivated at neutral pH. When plasma, after acid-dialysis, is kept at neutral pH a different form of active renin is generated, which remains active. The irreversible activation of prorenin depends on factor XII-initiated kallikrein formation. C1-inhibitor (C1-INH) and alpha 2-macroglobulin (alpha 2M) can be selectively denaturated by treatment of plasma at low pH values to which kallikrein and renin are resistant. After denaturation of C1-INH at pH 4-5, factor XII becomes capable of activating prekallikrein. The kallikrein that is formed after restoration of pH is complexed with alpha 2M. This complex has little activity towards natural protein substrates including prorenin. alpha 2M is denaturated at pH 3-4 and, as a consequence, kallikrein that is formed after restoration of pH is not complexed with alpha 2M. This kallikrein is able to attack both high-molecular weight kininogen and prorenin as manifested by the generation of bradykinin-forming and angiotensin-forming activities. These observations show a crucial role for C1-INH and alpha 2M in prorenin activation and explain, at least in part, why the pH of the acid-treatment step has to be less than 4 before irreversible activation of prorenin at neutral pH can occur.

Cold Temperature↗
PubMed1996

Radiographic contrast media and the coagulation and complement systems.

Intravascular contrast agents have several side effects including alterations of the hemostasis and the complement system. The effects on these systems may be one of the main causes of the "adverse contrast agent reaction." In vitro and in vivo evidence is provided that both ionic and nonionic contrast media activate the plasma kallikrein with consecutive activation of the factor XII-contact phase and stimulation of the bradykinin generation. Furthermore, activation of the complement cascade via the classic and the alternative pathways was described to a various extent for intravascular application of contrast agents. In non-reactors, these alterations are transient and only have a limited extent indicating that these reactions are within the regulatory capacity of the kallikrein-kinin-factor XII system. In reactors, however, significant evidence for an extended activation of the kallikrein system is associated with reduced levels of C1-esterase inhibitor. Therefore, patients with alterations in these systems should be regarded as candidates for adverse contrast agent reactions. Furthermore, contrast media influence the blood coagulation, especially in contact to artificial surfaces (plastic or glass). In vitro findings suggest that there is a broad scope of modifications caused by contrast agents indicating a modification of the risk of thromboembolism during angiography. Preliminary data suggest that an inhibition of clot formation is more effective with ionic compared with nonionic contrast agents. In summary, radiographic contrast agents have an impact both on the hemostasis and the complement systems. The effects may be of importance for adverse reactions as well as for thromboembolic complications during angiography.

Blood Coagulation↗
PubMed1981

The lupus inhibitor: a study of its heterogeneity.

The plasmas of six patients with prolonged activated partial thromboplastin times were studied in detail. In five of the six, the Russell's viper venom and prothrombin times were likewise prolonged. Five of the patients had documented systemic lupus erythematosus; one lacked the necessary criteria for this diagnosis. On quantitation, factor XI was decreased in all six; factors X and XII were diminished in five of the six. When tested for inhibitory activity, plasma from each of the patients prolonged the celite eluate inhibition test for factor XII and/or XI inhibition. In the formation of the Xa-V-phospholipid-Ca2+ complex (prothrombinase), factors X and Xa were inhibited to a greater degree than factor V or the phospholipid. Finally, each plasma was isofocused, the inhibitory fractions were identified and the clotting factor specificity of each inhibitory peak was determined. Fractions inhibitory against factors XI and XII isofocused with the IgG in each patient's plasma. Based on the data presented from these six patients, the "lupus inhibitor" is in fact a heterogeneous collection of inhibitors directed against factors XII, XI and X rather than a homogeneous entity.

Adolescent↗
PubMed1988

Effectiveness, specificity and safety of intranasal 1-deamino-8-D-arginine vasopressin treatment of normal blood donors.

A study of the absorption of 300 micrograms of 1-deamino-8-D-arginine vasopressin (DDAVP) given intranasally to normal blood donors was carried out to determine (a) the correlation between plasma levels of DDAVP and the percent rise of factor VIII procoagulant activity (VIII:C) and (b) the efficacy, specificity and safety of this treatment in increasing the recovery of factor VIII:C in donated blood. The maximum drug concentration was highly correlated to the maximum percent rise of VIII:C (r = 0.858, p less than 0.01). A differentiated effect of DDAVP on increases of VIII:C, VIII:Ag, vWF:Ag and vWF multimers was observed. A transient rise of fibrinopeptide A from 5 to 16 ng/ml, 30 min post-DDAVP, was not accompanied by changes in fibrinogen levels or generation of detectable factor Xa or thrombin. DDAVP had no effect on the factor XII-dependent pathway of plasminogen activation, or on the donor's vital signs and hematological parameters. Side effects were minor and of short duration. Intranasal DDAVP treatment of blood donors is considered to be a practical means of improving the recovery of VIII:C from normal donors.

Administration, Intranasal↗
PubMed1980

The influence of serum on random migration and chemotaxis of polymorphonuclear leucocytes: methodological evaluation using sera from infection-prone patients and normals.

The effects on normal polymorphonuclear leucocytes (PMN) of chemotactic and chemokinetic factors in sera from normal subjects and infection-prone patients were examined by means of the leading-front technique, using a modified Boyden chamber. The analysis scheme used made it possible to differentiate between chemotactic and chemokinetic factors and demonstrated that different factors account for the major chemotactic and chemokinetic activities of serum. The major chemotactic activity of unactivated serum was heat-labile, and the chemotactic activity of factor XII-deficient sera was normal, suggesting the major chemotactic activity to be distinct from C5a and factor XII-dependent pathways. The existence of both heat-stable and heat-labile chemokinetic factors was shown. The possibility that the reduced chemokinetic effect of several patient sera was caused by abnormal levels of the serum proteins alpha 1-antitrypsin, alpha 2-macroglobulin and albumin was excluded.

Adolescent↗