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Results for “Factor XII Deficiency”

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PubMed1988

A patient with an interstitial deletion of the short arm of chromosome 6.

The clinical history and subsequent progress of a child with an interstitial deletion in the short arm of chromosome 6 is described. This abnormality coupled with a reduced Hageman factor (Factor XII) led to an earlier publication which suggested that this gene was localized to the breakpoint region involved. A review of similar phenotypes from the literature is presented.

Child, Preschool↗
PubMed1981

Platelet-coagulant protein interactions in contact activation.

Previous studies have suggested that human platelets can promote the activation of factor XI by two different mechanisms, one requiring factor XII and ADP-treated platelets and the other requiring collagen-treated platelets in the apparent absence of factor XII. To investigate these hypotheses, isolated platelets were tested for their capacity to promote the activation and cleavage of purified factors XII and XI in various mixtures of purified factor XII, kallikrein, high molecular weight kininogen, and factor XI. That ADP- or collagen-treated platelets can promote the proteolytic activation of factor XII in mixtures containing kallikrein and HMW kininogen was shown by (1) the proteolytic cleavage of factor XII, (2) the development of factor XIIa coagulant activity, and (3) the proteolytic cleavage of 125I-labeled factor XII. Platelets treated with collagen or thrombin were shown to both coagulant assays and cleavage studies to participate with HMW kininogen and kallikrein in the proteolytic activation of factor XI by mechanisms that are partially dependent upon and partially independent of factor XII. These studies demonstrate that platelets can promote the proteolytic activation of factor XII by kallikrein and of factor XI by both factor XII-dependent and factor XII-independent mechanisms.

Adenosine Diphosphate↗
PubMed1982

Circulating anticoagulant against factor XII in smoldering leukemia.

A circulating anticoagulant against factor XII was detected in a patient with smoldering leukemia. Despite severe associated thrombocytopenia the patient suffered two thromboembolic episodes, besides mucosal bleeding. The circulating anticoagulant was demonstrated not only in the plasma but also in the serum. Its activity was not affected by heating at 56 degrees C for 30 min and it was not adsorbed by SO4Ba or A1(OH)3. The circulating anticoagulant was not dializable and demonstrated to be an IgG. This is apparently the first reported association of smoldering leukemia and a circulating anticoagulant against factor XII.

Blood Coagulation↗
PubMed1981

The role of HF cofactor in the Hageman factor-dependent fibrinolytic mechanism.

In 1969, Ogston et al. reported that the normal activation of fibrinolysis by surface contact requires, in addition to Hageman factor and plasminogen, a HF cofactor which is present in the euglobulin fraction and other factor(s) present in the supernatant. It has also been suggested that the glass-treated plasma is deficient in HF cofactor, In our laboratory the glass-treated plasma was found not to be deficient in HF or in a streptokinase-activated proactivator or in plasminogen. The glass-treated plasma was found deficient in prekallikrein in kininogen and in clotting factors XI, IX, VIII and V. The results presented indicate that HF cofactor activity is not different from that of kallikrein and that HF cofactor does not act as a plasminogen proactivator. Furthermore, the results indicate that the "other factors' present in the supernatant are not involved in contact-activated fibrinolysis.

Blood Coagulation Factors↗
PubMed1976

Adhesion of human blood platelets to glass polymer surfaces. II. Demonstration of the presence of a natural platelet adhesion inhibitor in plasma and serum.

Adhesiveness of washed platelets resuspended in citrated plasma, serum, or several different media has been investigated. A method specific for quanititation of adhesion was used. Platelets suspended in saline of Tyrode's solution were found to be highly adhesive to glass, polyethylene, polyvinyl chloride, or Cuprophane. This adhesiveness of platelets to test surfaces decreased by nearly 50% when plasma was the suspension medium. When the suspension medium was serum, the decrease in adhesion was nearly 75%. Cohn fraction V also decreased the adhesiveness of platelets significantly, but highly purfied albumin had only a small effect. Several pharmacologic agents decreased platelet adhesiveness when added to platelets suspended in plasma or serum, but had negligible effect on the adhesiveness of platelets suspended in artificial media devoid of proteins. Normal washed platelets, when suspended in citrated plasma obtained from an afibrinogenemic donor or in normal serum, showed a significant decrease in adhesion compared to the same platelets suspended in normal citrated plasma. Addition of fibrinogen to afibrinogenemic plasma or normal serum restored the adhesiveness of platelets to normal levels. Normal platelets resuspended in plasma obtained from a thrombasthenic donor exhibited normal adhesiveness. These observations suggested that while fibrinogen promotes platelet adhesion, plasma or serum possess also an adhesion-inhibiting activity.

Afibrinogenemia↗
PubMed1978

Chromogenic substrate assay of plasma prekallikrein. With a note on its site of biosynthesis.

A method for assaying plasma prekallikrein has been developed applying the chromogenic substrate Chromozym PK. Different variables have been investigated, and the final assay system was found to give a reproducible and reliable assay procedure. A normal value of 99.0 +/- 18% was found, the coefficient of variation being 7.9. Studies on material from patients with various liver diseases indicated that the main site of prekallikrein biosynthesis is the liver.

Adult↗
PubMed1978

Studies on assays for plasma prekallikrein and for the monitoring of coumarol therapy.

Chromogenic substrates were used to assay prekallikrein, prothrombin and factor X. Plasma prekallikrein was contact activated and allowed the splitting of HD-Pro-Phe-Arg-PNA which has affinity for plasma kallikrein. Prothrombin was assayed in various ways (immunologically, after activation with Ecarin or in a less specific way). Determination of factor X is considered as a possible specific method in the monitoring of coumarol therapy.

Coumarins↗
PubMed2005

Synergistic association between hypercholesterolemia and the C46T factor XII polymorphism for developing premature myocardial infarction.

Factor XII (FXII) plays a key role in both coagulation and fibrinolysis, thus its role in thrombotic processes is uncertain. Both genetic and environmental factors determine FXII plasma levels. A common C46T polymorphism in the Kozak region of F12 gene disturbs the translation of the protein leading to a significant reduction of FXII levels although its clinical significance is conflictive. We studied the F12 C46T polymorphism in 281 patients who had suffered from an acute myocardial infarction (MI) before 45-year-old and 550 control subjects from the same area. Serum levels of cholesterol, HDL, LDL, triglycerides and C reactive protein (CRP) were assayed in the MI group. The 46T allele slightly increased the risk to suffer from premature MI (OR: 1.64; 95% CI: 1.14-2.37; p = 0.008). Moreover, patients carrying the 46T allele showed increased levels of CRP (p = 0.002). Interestingly, we found that the simultaneous presence of the 46T allele and hypercholesterolemia increases the risk to develop premature MI 2.26 times. The F12 C46T polymorphism, associated with a reduction of plasma FXII levels, seems to play a deleterious effect, predisposing the development of premature MI, especially in hypercholesterolemic patients. This effect could be associated with an increased pro-inflammatory state, as the 46T allele associates with high levels of CRP.

Age Factors↗
PubMed1977

Activation and function of human Hageman factor. The role of high molecular weight kininogen and prekallikrein.

The activation and function of surface-bound Hageman factor in human plasma are dependent upon both high molecular weight (HMW) kininogen and prekallikrein. HMW kininogen does not affect the binding of Hageman factor to surfaces, but it enhances the function of surface-bound Hageman factor as assessed by its ability to activate prekallikrein and Factor XI. The initial conversion of prekallikrein to kallikrein by the surface-bound Hageman factor in the presence of HMW kininogen is followed by a rapid enzymatic activation of Hageman factor by kallikrein. The latter interaction is also facilitated by HMW kininogen. Kallikrein therefore functions as an activator of Hageman factor by a positive feedback mechanism and generates most of the activated Hageman factor during brief exposure of plasma to activating surfaces. HMW kininogen is a cofactor in the enzymatic activation of Hageman factor by kallikrein and it also augments the function of the activated Hageman factor generated. The stoichiometry of the Hagman factor interaction with HMW kininogen suggests that it enhances the activity of the active site of Hageman factor. Since HMW kininogen and prekallikrein circulate as a complex, HMW kininogen may also place the prekallikrein in an optimal position for its reciprocal interaction with Hageman factor to proceed. The surface appears to play a passive role upon which bound Hageman factor and the prekallikrein-HMW kininogen complex can interact.

Binding Sites↗
PubMed1977

Potentiation of the function of Hageman factor fragments by high molecular weight kininogen.

Patients lacking high molecular weight (HMW) kininogen have profound abnormalities of the Hageman factor-dependent pathways of coagulation, kinin formation, and fibrinolysis. The ability of HMW kininogen to potentiate the Hageman factor fragments (HFf) activation of prekallikrein and Factor XI in plasma was studied. HFf only partially converted Factor XI to XIa and prekallikrein to kallikrein in plasma deficient in HMW kininogen (Williams trait), while enhanced activation of Factor XI and prekallikrein by HFf resulted after reconstitution with HMW kininogen. In a system using highly purified components, HMW kininogen increased the initial rate of prekallikrein activation whether the kallikrein formed was assayed by arginine esterase activity or kininforming ability. The potentiation of prekallikrein activation occurred over a 12-fold range of enzyme (HFf) concentration and was nonhyperbolic with respect to substrate (prekallikrein). HMW kininogen exerted its effect even in the absence of prekallikrein since the hydrolysis of acetylglycyl-lysine methyl ester by HFf was increased by HMW kininogen. These results suggest that one of the functions of HMW kininogen is to augment the catalytic action of HFf.

Blood Coagulation Disorders↗
PubMed1986

Human platelet aggregation is initiated by peripheral blood mononuclear cells exposed to bacterial lipopolysaccharide in vitro.

Platelet consumption is a prominent feature of disseminated intravascular coagulation. We investigated whether monocyte procoagulant activity (PCA) might play a role in platelet consumption associated with gram-negative septicemia. Human mononuclear cells exposed in vitro to lipopolysaccharide demonstrated parallel dose-dependent increases in PCA and ability to induce platelet aggregation. Induction of platelet aggregation required the generation of thrombin dependent on coagulation Factors VII, X, and II, and calcium. This is consistent with monocyte tissue factor initiating thrombin generation. A specific monoclonal antimonocyte antibody was used to identify monocytes via indirect immunofluorescence, and demonstrated that all monocytes were included in platelet aggregates. Mononuclear cells that did not express PCA did not induce platelet aggregation and monocytes were not surrounded by platelet clumps. These data suggest that monocytes induced to express tissue factor on their surface may be important mediators of endotoxin-induced platelet, as well as fibrinogen, consumption.

Blood Coagulation↗
PubMed2007

Qualitative thrombelastographic detection of tissue factor in human plasma.

BACKGROUND: Tissue factor (TF) is the principal in vivo initiator of coagulation, with normal circulating TF concentrations reported to be approximately 23-158 pg/mL. However, patients with atherosclerosis or cancer have been reported to have TF concentrations ranging between 800 and 9000 pg/mL. Of interest, thrombelastographic (TEG)-based measures of clot initiation and propagation have demonstrated hypercoagulability in such patients at risk for thromboembolic events. Thus, our goal in the present investigation was to establish a concentration-response relationship of the effect of TF on TEG variables, and determine specificity of TF-mediated events with a monoclonal TF antibody. METHODS: Thrombelastography was performed on normal human plasma exposed to 0, 500, 1000, or 2000 pg/mL TF. Additional experiments with plasma exposed to 0 or 750 pg/mL TF in the presence or absence of a monoclonal TF antibody (1:360 dilution, 10 min incubation) were also performed. Clot initiation time (R) and the speed of clot propagation (MRTG, maximum rate of thrombus generation) were determined. RESULTS: The addition of TF to normal plasma resulted in a significant, concentration-dependent decrease in R and increase MRTG values. The addition of TF antibody to samples with TF significantly increased R and decreased MRTG values compared to samples with TF addition. CONCLUSIONS: In conclusion, changes in TEG variables in conjunction with use of a TF antibody can detect pathological concentrations of TF in human plasma in vitro. Further investigation is warranted to determine if TEG(R)-based monitoring could assist in the detection and prevention of TF-initiated thromboembolic events.

Blood Coagulation↗