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A comparison of murine and human factor XI.

Factor XI is a plasma glycoprotein that is required for contact activation initiated fibrin formation in vitro and for normal hemostasis in vivo. In preparation for developing a mouse model of factor XI deficiency to facilitate investigations into this protease's contributions to coagulation, we cloned the complementary DNA for murine factor XI, expressed the protein in a mammalian expression system, and compared its properties with human recombinant factor XI. The 2.8-kb murine cDNA codes for a protein of 624 amino acids with 78% homology to human factor XI. Both recombinant murine and human factor XI are 160 kD homodimers comprised of two 80 kD polypeptides connected by disulfide bonds. Murine factor XI shortens the clotting time of human factor XI deficient plasma in an activated partial thromboplastin time assay, with a specific activity 50% to 70% that of the human protein. In a purified system, murine factor XI is activated by human factor XIIa and thrombin in the presence of dextran sulfate. Murine factor XI differs from human factor XI in that it undergoes autoactivation slowly in the presence of dextran sulfate. This is due primarily to murine factor XIa preferentially cleaving a site on zymogen factor XI within the light chain, rather than the activation site between Arg371 and Val372. Northern blots of polyadenylated messenger RNA show that murine factor XI message is expressed, as expected, primarily in the liver. In contrast, messenger RNA for human factor XI was identified in liver, pancreas, and kidney. The studies show that murine and human factor XI have similar structural and enzymatic properties. However, there may be variations in tissue specific expression and subtle differences in enzyme activity across species.

Amino Acid Sequence↗

[Isolated increased aPTT with anamnestic hemorrhagic diathesis--severe FXI deficiency].

A 47-year-old patient with several episodes of bleeding after tonsillectomy, after an excision of a sacral dermoid and after urinary tract surgery presented with a mechanical ileus and was admitted to the department of visceral surgery. Preoperative analysis revealed a prolonged activated partial thromboplastin time (aPTT) of 93 seconds (normal range: 40-60 seconds), whereas the prothrombin time and thrombin time were normal. A mixture of 1 volume patient plasma and 1 volume normal plasma gave a normal aPTT, both before and after incubation of the plasma mixture at 37 degrees C for 1 hour. The patient's history and the prolonged aPTT as the only abnormal clotting test indicated deficiency of either factor VIII, factor IX, factor XI or von Willebrand factor with consecutively diminished factor VIII. Laboratory analysis revealed a factor XI of 4% indicating severe factor XI deficiency. Laparotomy was successfully performed without any hemorrhagic complications under fresh frozen plasma substitution.

Diagnosis, Differential↗

Congenital hemorrhagic disorders in Jordan.

The results of a three year prospective study of inherited bleeding syndromes in Jordan is presented. There were 112 patients from 64 families. Of these there were 42 patients with hemophilia A, 23 with Glanzmann's thrombasthenia, 22 with von Willebrand's disease, 11 with Christmas disease, 6 with hypofibrinogenemia, 3 with afibrinogenemia, 2 with factor XIII deficiency, 2 with storage pool disease and 1 with factor XI deficiency. The pattern of inherited bleeding syndromes in Jordan is different from that seen in Europe and U.S.A. in that Glanzmann's thrombasthenia is very common. High proportion of hemophiliacs were severe. Arthropathy was common. A significant number of bleeders had fatal hemorrhage. In a high proportion of patients, no family history of bleeding was found.

Adolescent↗

Activated factor IX-antithrombin III complexes in human blood: quantification by an enzyme-linked differential antibody immunoassay and determination of the in vivo half-life.

An enzyme-linked immunoassay has been developed to quantitate the activated human factor IX-antithrombin III complex (IXa-AT III). Test plasma was absorbed onto barium citrate and eluted to remove free antithrombin III (AT III). The IXa-AT III complex in the eluate was then measured by using polystyrene balls coated with immobilized rabbit anti-AT III antibody-binding fragments and anti-factor IX (anti-FIX) antibody-binding fragments labeled with beta-D-galactosidase. The assay was very sensitive, detecting a concentration as low as 0.15 fmol/assay/100 microliters plasma, which corresponds to as little as 0.002% of activated FIX in plasma. Experiments with purified FIX, IXa-alpha, AT III, IXa-AT III, normal plasma, AT III-depleted plasma, and FIX-deficient plasma demonstrated that the assay is specific. IXa-AT III generation could be detected in normal native whole blood within 2.0 minutes after venipuncture. The complex could not be detected in native whole blood from patients with severe hemophilia B even at 1 hour after venipuncture. The mean plasma level of IXa-AT III in healthy adults (n = 32, ages 23 to 54 years) was 9.67 +/- 2.86 pmol/L (mean +/- SD), whereas in eight patients with disseminated intravascular coagulation levels ranged from 11.7 to 35.0 pmol/L. The IXa-AT III titer was significantly reduced in three patients with severe factor VII deficiency (5.70 +/- 1.99 pmol/L) but was normal in three patients with severe factor XI deficiency (11.2 +/- 1.59 pmol/L). Purified IXa-AT III was cleared in vivo in rabbits with a half-life value of 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

The use of epsilon-aminocaproic acid for the management of hemophilia in dental and oral surgery patients.

The use of epsilon-aminocaproic acid has proved to be an efficient and practical method for treating hemophiliacs who require dental work. In the past, patients requiring extractions were admitted to a hospital for approximately ten days and received replacement infusions every 12 hours during their stay. This resulted in a large expense because of the cost of the material and the hospitalization itself, not to mention the trauma sustained by the patient both physically and psychologically. Also, by decreasing the number of factor infusions, the risk of complications such as the transmission of hepatitis, allergic reaction, or inhibitor formation decreased. The same protocol using a single infusion of the appropriate factor replacement with supplementary epsilon-aminocaproic acid can be used for the management of patients with other coagulation disorders such as factor IX deficiency (Christman disease), factor XI deficiency, and von Willebrand's disease. Since this paper was submitted, seven more patients have been treated using this protocol. An additional seven odontectomies, 33 extractions, operative dentistry in 18 quadrants, and alveoloplasties in two full arches have been performed. This brings the total to 23 treatment sesions with 18 patients undergoing 124 procedures. One additional minor bleeding episode occurred, resulting in a total rate of four bleeding episodes in 23 treatment sessions and 124 procedures. Our incidence of complications secondary to epsilon-aminocaproic acid specifically remains zero.

Adolescent↗

Williams-Beuren syndrome associated with caudal regression syndrome and coagulopathy--a case report.

Williams-Beuren syndrome is a genetic disorder caused by a heterozygous deletion at 7q11.23. The present report describes a female patient with Williams-Beuren syndrome combined with caudal regression syndrome and two forms of coagulopathy. Besides the typical developmental abnormalities such as mental and growth retardation, a distinctive facial appearance, and cardiovascular anomalies, our patient showed fusion of fourth and fifth lumbar vertebra and a sacrococcygeal agenesis. Blood coagulation tests revealed a deficiency of coagulation factor XI and XII. Magnetic resonance imaging angiography showed multiple vascular stenoses mainly in the abdominal aorta and its major branches as a consequence of the insufficient elastin gene. Previous reports identified a deletion of HLXB9 as a possible genetic cause of the caudal regression syndrome, which could not be identified in the present case. This unusual combination of the above-mentioned genetic disorders has not been published so far.

Adult↗

Supernumerary nipples in children with hematologic disorders.

The authors report on supernumerary nipples and various hematologic disorders in 7 patients [factor X deficiency (n = 1), factor XI deficiency (n = 2), acute lymphoblastic leukemia (n = 3), and acute myeloblastic leukemia (n = 1)]. They would like to draw attention to the association of supernumerary nipples with hematological disorders, which has not been published before and is considered to be added to the anomalies associated with supernumerary nipples.

Abnormalities, Multiple↗

Blood coagulation in hemophilia A and hemophilia C.

Tissue factor (TF)-induced coagulation was compared in contact pathway suppressed human blood from normal, factor VIII-deficient, and factor XI-deficient donors. The progress of the reaction was analyzed in quenched samples by immunoassay and immunoblotting for fibrinopeptide A (FPA), thrombin-antithrombin (TAT), factor V activation, and osteonectin. In hemophilia A blood (factor VIII:C <1%) treated with 25 pmol/L TF, clotting was significantly delayed versus normal, whereas replacement with recombinant factor VIII (1 U/mL) restored the clot time near normal values. Fibrinopeptide A release was slower over the course of the experiment than in normal blood or hemophilic blood with factor VIII replaced, but significant release was observed by the end of the experiment. Factor V activation was significantly impaired, with both the heavy and light chains presenting more slowly than in the normal or replacement cases. Differences in platelet activation (osteonectin release) between normal and factor VIII-deficient blood were small, with the midpoint of the profiles observed within 1 minute of each other. Thrombin generation during the propagation phase (subsequent to clotting) was greatly impaired in factor VIII deficiency, being depressed to less than 1/29 (<1.9 nmol TAT/L/min) the rate in normal blood (55 nmol TAT/L/min). Replacement with recombinant factor VIII normalized the rate of TAT generation. Thus, coagulation in hemophilia A blood at 25 pmol/L TF is impaired, with significantly slower thrombin generation than normal during the propagation phase; this reduced thrombin appears to affect FPA production and factor V activation more profoundly than platelet activation. At the same level of TF in factor XI-deficient blood (XI:C <2%), only minor differences in clotting or product formation (FPA, osteonectin, and factor Va) were observed. Using reduced levels of initiator (5 pmol/L TF), the reaction was more strongly influenced by factor XI deficiency. Clot formation was delayed from 11.1 to 15.7 minutes, which shortened to 9.7 minutes with factor XI replacement. The maximum thrombin generation rate observed ( approximately 37 nmol TAT/L/min) was approximately one third that for normal (110 nmol/L TAT/min) or with factor XI replacement (119 nmol TAT/L/min). FPA release, factor V activation, and release of platelet osteonectin were slower in factor XI-deficient blood than in normal blood. The data demonstrate that factor XI deficiency results in significantly delayed clot formation only at sufficiently low TF concentrations. However, even at these low TF concentrations, significant thrombin is generated in the propagation phase after formation of the initial clot in hemophilia C blood.

Adolescent↗

Factor XI and platelets: Evidence that platelets contain only minimal factor XI activity and antigen.

Factor-XI activity of platelets has been studied in platelet-rich plasmas and isolated platelet suspensions. Fresh platelets in both environments had little or no measurable factor-XI activity. Frozen and thawed platelet-rich normal plasma had markedly elevated apparent factor-XI activity and factor-XI activity as compared to platelet-poor plasma. Frozen and thawed platelet-rich and platelet-poor normal plasmas had equivalent factor-XI antigen. Platelets isolated from normal blood and from factor-XI deficient blood had the same small amounts of apparent factor-XI activity, which increased slightly on freezing and thawing. The data indicates that minimal factor XI is associated with the platelet. The markedly elevated apparent factor-XI activity of frozen and thawed platelet-rich plasma is shown to reflect the interaction of a platelet activator with plasma clotting factors to produce a later activated-clotting-intermediate.

Antigens↗

[Hemophilia C, a deficiency of a contact phase protein which may involve a risk of hemorrhage].

Factor XI deficiency, also called hemophilia C, was first described in 1953. It is thought to constitute 7% of all disorders of the intrinsic pathway of blood coagulation. It represents the only deficiency of a contact phase protein associated with a bleeding tendency with widely variable expression. Eighteen members of 5 families with this deficiency have been investigated; only 3 exhibited a hemorrhagic diathesis: 2/4 homozygous (hemorrhages after surgical procedures and hematomas and after minor traumatism) and 1/10 heterozygous individuals (hematomas, epistaxis). All homozygotes had a prolongation of the PTT. The hemorrhagic tendency was higher among homozygous individuals (with very low factor XI activity), but 2 were asymptomatic. Heterozygotes may also bleed. This deficiency is found mainly in an Ashkenazy Jewish population. Our study shows that it occurs in an apparently autochthonous Swiss population. A detailed history and studies of other family members are necessary if there is suspicion of factor XI deficiency.

Adult↗

Production and therapeutic use of a factor XI concentrate from plasma.

Factor XI deficiency is an uncommon bleeding disorder usually manifested by excessive bleeding after surgery or trauma. Until recently the only effective therapy has been fresh-frozen plasma (FFP) infusion. We describe the efficacy and safety of a new factor XI concentrate produced from human donor plasma by a modification of the method used for antithrombin III concentrate. The mean recovery of factor XI in the circulation measured on 62 occasions was approximately 91% of the injected dose, and the mean half-disappearance-time was 52 h. The concentrate was used for 31 invasive procedures in 30 patients, including 16 patients who had a definite bleeding tendency on previous occasions, with normal haemostasis being achieved in all but 1. Only 1 patient (previously experiencing allergy to FFP) experienced adverse effects during infusion. Monitoring of liver function tests and viral antibody status in suitable patients has shown no evidence of transmission of hepatitis viruses, HIV-1 or parvovirus B19. We conclude that this concentrate provides effective treatment for patients with factor XI deficiency. Preliminary results suggest safety from virus transmission, but this needs to be established in further studies of previously untreated patients.

Adolescent↗

Transmission of factor VII deficiency through liver transplantation.

The liver is the primary site of synthesis for the majority of coagulation factors. There are published accounts of liver donor-to-recipient transmission of protein C deficiency with dysfibrinogenemia and factor XI deficiency. In this article, we report what we believe to be the first observation, of transmission of factor VII deficiency, a rare, autosomal recessive coagulation disorder, from an affected liver donor to a naive liver recipient. At 300 days after transplantation, the recipient remains with an isolated prolongation of the prothrombin time and a below-normal level of factor VII, and has had no bleeding complications.

Adult↗

The soluble recombinant form of a binding protein/receptor for the globular domain of C1q (gC1qR) enhances blood coagulation.

The gC1qR is a ubiquitously expressed, 33 kDa cellular protein which recognizes the globular domains of C1q. Recent evidence suggests that the gC1qR also serves as the Zn(++)-dependent endothelial cell binding site for factor XII and high-molecular-weight kininogen, and activates intrinsic coagulation and kinin pathways in purified systems. In addition, activated lymphocytes have been reported to release soluble gC1qR. Thus, the present study investigated the procoagulant potential of soluble gC1qR in human plasma using the recombinant protein (rgC1qR). rgC1qR supported a dose-dependent shortening of extrinsic coagulation using the prothrombin time in the presence of diluted (1/50-1/500) thromboplastin. Maximum enhancement of the prothrombin time resulted in shortening of the clotting time from 78.8 +/- 0.4 s to 68.5 +/- 0.6 s (mean +/- SD, n = 8) in the presence of 50 micrograms/ml (1.5 mumol/l) rgC1qR. rgC1qR also enhanced the intrinsic pathway of coagulation evaluated in the absence of activators of the contact system, as demonstrated by a shortening of the plasma recalcification time from 348 +/- 66 s to 140 +/- 23 s (n = 4). rgC1qR, however, had no effect on intrinsic coagulation in the presence of undiluted kaolin or ellagic acid, and under these conditions failed to shorten the activated partial thromboplastin time of factor VIII or factor-IX-deficient plasma. rgC1qR further failed to affect thrombin and factor Xa generation assayed using chromogenic substrates, and did not enhance thrombin-induced conversion of fibrinogen to fibrin. Interestingly, the procoagulant activity of the rgC1qR was measurable in either factor-XII- or factor-XI-deficient plasma, suggesting that it was not exclusively focused on the contact system of coagulation. Although the mechanism of action of gC1qR on blood coagulation remains obscure, the data suggest a potential role for this protein in hemostatic and thrombotic events.

Blood Coagulation↗

Congenital bleeding disorders. Rational treatment options.

There are rational, effective choices available for the treatment of common inherited bleeding disorders, according to assessment of safety, efficacy and cost. All currently available products for patients with haemophilia A (factor VIII deficiency) are comparable in terms of efficacy and viral safety. However, high purity products are recommended for those with coexisting human immunodeficiency virus (HIV) infection. Many patients with mild haemophilia A and most with von Willebrand's disease can be treated with desmopressin, which can be given as an intranasal spray in some countries. For the treatment of patients with factor XI deficiency, fresh frozen plasma remains the standard care, although solvent-detergent-treated fresh frozen plasma and factor XI concentrate are currently being investigated as alternatives. In the treatment of haemophilia B (factor IX deficiency), purified factor IX concentrates are particularly useful in clinical settings where large amounts of concentrate are to be used (e.g. surgical prophylaxis). Their usefulness in other contexts needs clarification. Treatment of inhibitors that may develop in response to administered coagulation factors is still limited to the use of prothrombin complex concentrates and porcine factor VIII. Active clinical trials are currently assessing the efficacy and safety of recombinant factor VIIa, Xa and tissue factor in this indication.

Autoimmune Diseases↗

Interactions among Hageman factor (HG, Factor XII), plasma thromboplastin antecedent (PTA, Factor XI), plasma prekallikrein (PK, Fletcher factor) and high molecular weight kininogen (HMW-K, Fitzgerald factor) in blood coagulation.

Studies of plasmas from individuals with Hageman trait (factor XII deficiency), plasma thromboplastin antecedent (PTA, factor XI) deficiency, Fletcher trait (plasma prekallikrein deficiency) and Fitzgerald trait (high molecular weight-kininogen deficiency) have revealed the importance of these proteins in blood coagulation. The interactions among them, however, are not fully elucidated. We have studied these reactions by two different approaches. (1) In a purified system, high molecular weight kininogen was absolutely required for activation of PTA by HF and ellagic acid (EA). The yield of activated PTA was proportional to the amount of HF, HMW-K, and PTA in the mixtures, suggesting that these three proteins may form a complex in the presence of EA. (2) In experiments with whole plasma, we took advantage of the adsorption of EA to Sephadex gels. When normal plasma or plasma deficient in HF, PK, HMW-K or PTA was exposed to Sephadex-EA and was separated by centrifugation, each supernatant plasma except that deficient in HF shortened the prolonged partial thromboplastin time (PTT) of HF-deficient plasma. Plasma simultaneously depleted of HMW-K, PK and PTA also shortened the PTT of HF-deficient plasma and of plasma depleted of HF and PK, but had virtually no procoagulant effect upon the PTT of plasma depleted of HF and MHW-K. Thus, exposure of HF in plasma to Sephadex-EA appeared to generate a clot-promoting form of HF in the absence of other clotting factors, but its expression required the presence of HMW-K.

Blood Coagulation↗

Factor XII deficiency acquired by orthotopic liver transplantation: case report and review of the literature.

Transmission of congenital clotting factor deficiencies after orthotopic liver transplantation is rare. There are published reports of liver donor-to-recipient transmission of protein C deficiency with dysfibrinogenemia, protein S, factor VII and factor XI deficiencies. We report a case of transmission of factor XII deficiency with liver transplantation in a patient with Budd-Chiari syndrome. There was a persistent elevation of the activated partial thromboplastin time (aPTT), but no evidence of bleeding while the patient was maintained on warfarin. The presence of a persistently abnormal aPTT may raise suspicion for the presence of a clotting factor deficiency; however, deficiencies of other clotting factors may not be readily apparent on routine blood tests performed in a donor. Being aware of the possibilities of transmission of these inherited deficiencies of coagulation factors will aid in their early detection and management in the transplant donor and recipient.

Diagnosis, Differential↗