[Congenital factor 13 deficiency: severe abdominal hemorrhage after combined antiinflammatory therapy].
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Purified acid-soluble and insoluble human collagen accelerated the clotting of plateletpoor plasma in silicone-treated tubes. The clot-promoting effect did not appear to be due to thromboplastic activity since the collagen preparations did not activate factor X in the presence of factor VII and calcium. Instead, collagen appeared to accelerate clotting by activating Hageman factor (factor XII) on the basis of the following findings: collagen increased the clot-promoting activity of partially purified Hageman factor but exerted no further effect in the presence of kaolin, a known activator of Hageman factor; clot-promoting eluates were obtained from collagen exposed to normal, hemophilic, or PTC-deficient plasma but not from collagen exposed to Hageman or PTA-deficient plasma. The collagen molecule itself appeared to be required for the clot-promoting activity since digestion with collagenase or thermal denaturation at pH 2.5 (about 35 degrees C) resulted in very marked reduction in clot-promoting activity. Since thermal denaturation is associated with transformation of collagen structure from triple helical to random coil form, it is suggested that the native form of collagen is essential for the ability to activate Hageman factor. Blockage of the free amino groups by treatment with nitrous acid or dinitrofluorobenzene only slightly reduced the clot-promoting activity of collagen. In contrast, since addition of cationic proteins to collagen markedly reduced pro-coagulant activity it is suggested that negatively charged sites on the collagen molecule are critical for Hageman factor activation. This suggestion is supported by the finding that pepsin treatment of collagen, which removes the predominantly negatively charged telopeptides, results in significant decrease in coagulant activity. Esterification of collagen, which neutralizes 80-90% of the free carboxyl groups, reduced coagulant activity by over 90% and it is suggested that the free carboxyl groups of glutamic and aspartic acids provide the negatively charged sites critical for Hageman factor activation.
Of five IgGI/k murine monoclonal anti-human prekallikrein antibodies produced (MAbs), MAb 13G11 was selected for studying interaction of prekallikrein with factor XII and high-mol-wt kininogen (HMWK) during activation on a surface. Immunoblots from sodium dodecyl sulfate (SDS) gels showed that this MAb recognizes two variants (88 kd and 85 kd) of prekallikrein and kallikrein both in purified proteins and normal plasma. Under reducing conditions, kallikrein exhibits the epitope on the heavy chain but not on the light chains. Preincubation of MAb 13G11 with prekallikrein (added to prekallikrein-deficient plasma) or with normal plasma inhibited surface activation of prekallikrein 60% to 80%, as judged by amidolytic and coagulant assays. In normal plasma, inhibition by the Fab fragments was 87% of that with the entire MAb. Inhibition was not by competition between the MAb and HMWK, since neither binding of 13G11 to prekallikrein (coated on microtiter plates) was inhibited by an excess of HMWK, nor was hydrolysis of HMWK by kallikrein inhibited by 13G11. Using purified proteins in a system mimicking contact activation, inhibition by 13G11 of prekallikrein activation by factor XIIa, HMWK, and kaolin present was approximately 80%. Decreased inhibition (55% to 25%) occurred without HMWK or when kallikrein was used instead of prekallikrein. Kallikrein activity was not inhibited by 13G11 Fab fragments. These results indicate that the effect of 13G11 in plasma was neither dissociation of prekallikrein-HMWK complex nor a direct effect on kallikrein activity. Similar to the results in plasma, activation of prekallikrein, HMWK present, by factor XIIa bound to kaolin, was inhibited approximately 70% by 13G11. The results suggest a previously unrecognized site on the prekallikrein (heavy chain) required for its interaction with factor XIIa, either shared with the 13G11 epitope or located in very close proximity. The inhibition of kallikrein by intact 13G11 indicates that its binding site on the heavy chain is sterically related to the active site (light chain).
The mechanisms by which human high molecular weight kininogen (HMKrK) contributes to the surface-dependent activation of the Hageman factor systems have been studied. The ability of various mixtures of purified human Hageman factor (coagulation factor XII), HMrK, prekallikrein, and kaolin to activate coagulation factor XI was determined with factor XIa (activated factor XI) clotting assays. Hageman factor, HMrK and prekallikrein were required for maximal rates of activation of factor XI. A certain optimal mixture of purified Hageman factor, HMrK, prekallikrein, and kaolin gave the same rapid initial rate of activation of purified factor XI as an equivalent aliquot of factor XI-deficient plasma. This suggests that potent, surface-mediated activation of factor XI in plasma is explicable in terms of Hageman factor, HMrK, and prekallikrein. By studying separately some of the surface-dependent reactions involving Hageman factor, it was found that HMrK accelerated by at least an order of magnitude the following reactions: (i) the activation of factor XI by activated Hageman factor; (ii) the activation of prekallikrein by activated Hageman factor; and (iii) the activation of Hageman factor by kallikrein. Stoichiometric rather than catalytic amounts of HMrK gave optimal activation of factor XI. These results are consistent with the hypothesis that HMrK and Hageman factor form a complex on kaolin which renders Hageman factor more susceptible to proteolytic activation by kallikrein and which facilitates the action of activated Hageman factor on its substrate proteins, factor XI and prekallikrein.
To define the factors responsible for the inactivation of the active fragment derived from Factor XII (Factor XIIf ) in plasma, we studied the inactivation kinetics of Factor XIIf in various purified and plasma mixtures. We also analyzed the formation of 125I-Factor XIIf -inhibitor complexes by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In purified systems, the bimolecular rate constants for the reactions of Factor XIIf with C-1-inhibitor, alpha 2-antiplasmin, and antithrombin III were 18.5, 0.91, and 0.32 X 10(4) M-1 min-1, respectively. Furthermore, SDS-PAGE analysis revealed that 1:1 stoichiometric complexes were formed between 125I-Factor XIIf and each of these three inhibitors. In contrast, kinetic and SDS-PAGE studies indicated that Factor XIIf did not react with alpha 1-antitrypsin or alpha 2-macroglobulin. The inactivation rate constant of Factor XIIf by prekallikrein-deficient plasma was 14.4 X 10(-2) min-1, a value that was essentially identical to the value predicted from the studies in purified systems (15.5 X 10(-2) min-1). This constant was reduced to 1.8 X 10(-2) min-1 when Factor XIIf was inactivated by prekallikrein-deficient plasma that had been immunodepleted (less than 5%) of C-1-inhibitor. In addition, after inactivation in normal plasma, 74% of the active 125I-Factor XIIf was found to form a complex with C-1-inhibitor, whereas 26% of the enzyme formed complexes with alpha 2-antiplasmin and antithrombin III. Furthermore, 42% of the labeled enzyme was still complexed with C-1-inhibitor when 125I-Factor XII was inactivated in hereditary angioedema plasma that contained 32% of functional C-1-inhibitor. This study quantitatively demonstrates the dominant role of C-1-inhibitor in the inactivation of Factor XIIf in the plasma milieu.
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Synchronization of spermatogenesis would provide an ideal model for the investigation of stage-dependent changes in the secretion of paracrine factors. In vitamin A-deficient animals subsequently injected with vitamin A, over 80% of seminiferous tubules were synchronized within three to five stages of the seminiferous cycle. Following replenishment of vitamin A, spermatogenic stages IV-VI (35 days), VI-VIII (38 days), IX-XII (41 days), I-IV (45 days) and V-VII (48 days) were observed. Despite synchronization of spermatogenesis at all stages, spermatogenesis was markedly impaired when evaluated in a quantitative fashion. At all times evaluated, numbers of round spermatids were reduced compared with age-matched controls. Numbers of pachytene spermatocytes reached control values only after 45 days of vitamin A replenishment. Elongate spermatids were almost totally absent up to 41 days after vitamin A replenishment. Testicular and epididymal weights were also reduced, although testicular weights showed a significant recovery over the time-course of the study. Serum and pituitary concentrations of LH and FSH were raised at the commencement of the study, with serum gonadotrophins returning to control values 48 days after vitamin A replenishment. Both testicular and serum testosterone concentrations in treated animals tended to be higher than in the controls. Although synchronization of spermatogenesis was achieved, testicular testosterone concentrations did not reflect the stage-dependent cyclical changes observed in earlier studies. Testicular concentrations of testosterone were raised throughout the period of observation with the exception of animals synchronized around stages II-IV of the spermatogenic cycle. No correlation between the most frequent stages and intratesticular testosterone was found (r = 0.06, P greater than 0.1). Previous observations that testosterone concentrations are selectively increased at stages VII-VIII of the spermatogenic cycle are not supported by the present study.
UNLABELLED: Many studies have shown a high percentage of venous thromboses in children to be associated with haematological disorders. However, studies assessing the influence of haemostaseological disorders on paediatric stroke are rare. We compared 26 children with cerebral infarction (median age 2 months, range 0-16.2 years) and 17 with venous thrombosis (median age 4.5 years, range 0-17 years) with regard to prothrombotic risk factors. Prothrombotic disorders were found in 8 out of 26 patients with cerebral infarction (FV Leiden mutation: n = 4; protein C deficiency: n = 1; FV Leiden mutation + protein C deficiency: n = 2; prothrombin mutation G20210A: n = 1) and in 13 out of 17 with venous thrombosis (FV Leiden mutation n = 3; protein C deficiency n = 5; elevated HRGP + PAI: n = 1, combined deficiency of AT, protein C and plasminogen: n = 1; F XII deficiency: n = 1; lupus anticoagulans n = 1; FV Leiden + F XII deficiency + lupus anticoagulans + PAI: n = 1). Comparison of these prevalences with those of 150 healthy paediatric controls showed in children with FV Leiden mutation and/or protein C deficiency an increased risk of cerebral infarction (patients vs. controls: 26.9% vs. 6%; OR 5.77; 95%-CI 1.92-17.3; P = 0.0031) as well as of venous thrombosis (53% vs. 5.3% 19.9; 95%-CI 6-65.6; P < 0.0001). This result is in contrast with reports on thrombophilia in cerebral infarction in adult patients. CONCLUSION: Our results indicate that FV Leiden mutation and protein C deficiency may contribute to the multifactorial aetiology of stroke in early childhood.
The specific clot promoting activity of factor XII (F XII) in plasma samples from 50 healthy adults was between 30 and 48 U/mg, whereas the specific activity of purified F XII ranged from 55 to 66 U/mg. This difference was neither due to partial proteolytic activation during purification of F XII nor to the influence of plasma protease inhibitors. Purified F XII showed normal size and charge, as demonstrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing, respectively. The increase of the specific F XII activity during the purification process mainly occurred after anion exchange chromatography on DEAE-Sephadex and after the final gel filtration step. Upon dextran sulfate activation, proteolytic cleavage of F XII and generation of kallikrein-like amidolytic activity was faster in F XII deficient plasma containing purified F XII than in F XII deficient plasma containing a corresponding amount of pooled normal plasma (NHP). The binding to kaolin was similar for both, purified F XII and plasma F XII. In conclusion, purification alters the properties of F XII in an unknown way, resulting in an increased specific clot promoting activity.
Direct potential-mediated and time-controlled activation of purified human factor XII (FXII) immobilized on carbon has been demonstrated. Initial experiments were required to find a procedure for characterizing the immobilization of FXII and its activated form, factor XIIa (FXIIa). After achieving saturation of the carbon surface with FXII, surface catalytic activities could be generated under negative potential conditions. Activities depended on the duration and amplitude of the polarization applied to the immobilized FXII. The activities thus electrochemically induced in the surface-bound FXII molecules were tested biologically in the presence of normal human plasma and FXII-deficient plasma. The shortening of the activated partial thromboplastin time test suggested identity of the catalytic activities with that of activated FXII molecules. The electrochemical activation mechanism was consistently analysed according to first-order kinetics. The apparent rate constants increased in the presence of zinc ions.
Preincubation of lipopolysaccharides (LPS) of Bacteroides fragilis, Bacteroides vulgatus, and Fusobacterium mortiferum with purified human Hageman factor (HF) followed by addition of purified human prekallikrein resulted in the activation of HF, as measured by the generation of kallikrein using the tripeptide substrate N-alpha-benzoyl-L-proline-L-phenylalanine-L-arginine-4-nitroanilide. Addition of purified HF, which had been preincubated with the LPS, to HF-deficient plasma resulted in the acceleration of the recalcification time. Addition of the LPS to HF-deficient plasma reconstituted with various concentrations of HF also resulted in the acceleration of the recalcification time; the magnitude of the acceleration correlated with the amount of HF used to reconstitute the deficient plasma. These results demonstrate that LPS of selected gram-negative anaerobes activate HF and thereby initiate the intrinsic pathway of coagulation.
Ataxia-telangiectasia is clinically characterized by the presence of cerebellar ataxia, choreoathetosis, and oculocutaneous telangiectasia. Humorocellular immune deficiency may be associated with the disease. So far, no coagulation abnormalities have been reported in patients with ataxia-telangiectasia. Presence of Hageman factor deficiency in our patient could merely be a coincidental occurrence of two rare independent disease states. Since this coagulation abnormality in Hageman factor deficiency is rather subtle and not usually associated with clinically significant bleeding, this defect can be easily overlooked.
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The incomplete penetrance of thrombosis in familial protein C deficiency suggests disease occurs when this deficit is combined with additional abnormalities in the hemostatic system. The pattern of inherited thrombophilia in the Vermont II kindred, which is affected by a clinically dominant type I protein C deficiency, provides strong evidence for a second unidentified gene that segregates independently of protein C deficiency and increases susceptibility to thrombosis. To test the second gene hypothesis, thirty-four candidate genes for proteins involved in hemostasis or inflammation were tested as the unknown defect, using highly polymorphic short tandem repeat (STR) markers in an informative subset (n = 31) of the kindred. The genes considered are; alpha-fibrinogen, beta-fibrinogen, gamma-fibrinogen, prothrombin, tissue factor, factor V, protein S, complement component 4 binding protein, factor XI, factor XII, factor XIIIa, factor XIIIb, histidine rich glycoprotein, high molecular weight kininogen, kallikrein, von Willebrands factor, platelet factor 4, thrombospondin, antithrombin III, alpha-1-antitrypsin, thrombomodulin, plasminogen, tissue plasminogen activator, urokinase plasminogen activator, plasminogen activator inhibitor-1, plasminogen activator inhibitor-2, protein C inhibitor, alpha-2-plasmin inhibitor, kallistatin, lipoprotein a, interleukin 6, interleukin 1, cystathionine-beta-synthase, and methylenetetrahydrofolate reductase. Mutations in many of these genes have been previously established as independent risk factors for thrombosis. However, linkage analysis provided no evidence to implicate any of the candidate genes as the second inherited factor that promotes thrombophilia in this kindred.
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Unactivated partial thromboplastin antecedent (PTA) has been purified by sequential chromatography of plasma on quaternary aminoethyl Sephadex, sulphoprophyl Sephadex, Sephadex G-150, and passage over an anti-IgG immunoadsorbant. The preparation gave a single band after alkaline disc gel electrophoresis, sodium dodecyl sulfate (SDS) gel electrophoresis and isoelectric focusing in acrylamide gels and was found to have a mol wt of 175,000 by gel filtration, 163,000 by SDS gel electrophoresis, and an isoelectric point of 8.8-9.4 (peak 9.0-9.1). Pre-PTA was activated directly by activated Hageman factor or by Hageman factor prealbumin fragments. Its coagulant activity was inhibited by DFP, soybean trypsin inhibitor and trasylol but not by lima bean trypsin inhibitor or ovomucoid trypsin inhibitor indicating that activated PTA possesses the same inhibition profile utilizing these reagents as does plasma kallikrein. A major plasma inhibitor of activated PTA was found to be a 65,000 mol wt alpha-globulin which was isolated free of alpha(1)-chymotrypsin inhibitor, inter alpha-trypsin inhibitor, alpha(2)-macroglobulin, and the other known inhibitors of activated PTA, the activated first component of complement (C1 INH), and antithrombin III. Its physicochemical properties were identical to alpha(1)-antitrypsin, and it was absent in alpha(1)-antitrypsin-deficient plasma thereby identifying this PTA inhibitor as alpha(1)-antitrypsin.
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.
Highly purified preparations of Hageman factor, a potent clotpromoting agent in normal mammalian plasma, had a sedimentation coefficient of approximately 5S before activation. After activation, the Hageman factor behaved as a much less soluble or larger molecule during ultracentrifugation and gel filtration. No significant change in sedimentation behavior was noted when the Hageman factor in plasma deficient in plasma thromboplastin antecedent was activated. The altered sedimentation behavior of purified activated Hageman factor probably reflects its decreased solubility in aqueous media.