Factor XIII assay by an isotope method. II. Heparin inhibition of factor XIII activation.
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Factor XIII is the fibrin-stabilizing factor that covalently cross-links fibrin monomers to form a highly organized, stable fibrin clot. The plasma form of factor XIII is a heterodimer, a2b2, consisting of two a-chains and two b-chains; the intracellular form, such as in platelets and placenta, is a dimer, a2, consisting of a-chains only. The catalytic function of factor XIII, a transglutaminase, resides in the a-chain. To address questions regarding sites of synthesis of factor XIII a-chain, an EcoRI restriction fragment from the protein-coding region of the factor XIII a-chain cDNA was used as a probe for Northern blot analysis. The cDNA probe showed hybridization with a single approximately 4.0-kilobase (kb) message in poly (A)+ mRNA prepared from normal human peripheral blood monocytes and normal human liver. The results demonstrate conclusively that factor XIII a-chains are actively synthesized in circulating monocytes and in liver. To our knowledge, these data represent the first demonstration of synthesis of any blood coagulation factor in primary uncultured and unstimulated monocytes or macrophage cells.
Factor XIII is an endogenous clotting factor that retards thrombus degradation by cross-linking fibrin. To determine the efficacy of Factor XIII as a topical clot-stabilizing agent in preventing postoperative hemorrhage associated with coagulopathy, a rat model of experimental craniotomy and standardized bilateral frontal corticectomy was developed. In 25 rats (50 lesions), recombinant human Factor XIII or placebo solution was topically applied to corticectomy cavities after hemostasis was achieved; each animal served as its own control. In 20 rats, heparin sulfate (100 U/kg.h) was initiated intraperitoneally 3 days after surgery and was continually administered by an Alzet pump for 7 days, compared with a control group of 5 rats receiving saline intraperitoneally. The volume of intracranial hemorrhage was quantitatively determined from coronal sections by use of automated image analysis. Large (> 50 mm3) intracerebral hemorrhages were significantly more frequent in placebo (60%)- compared with recombinant Factor XIII (15%)-treated lesions (P < 0.01) in animals receiving heparin. The topical application of clot-stabilizing agents such as Factor XIII may reduce the risk of postoperative intracranial hemorrhage, especially in high-risk patients with coagulopathy.
Factor XIII from placenta was successfully grafted onto collagen membranes by the acyl-azide procedure. The transamidase activity retained on collagen membranes was determined by measuring the increase of fluorescence resulting from dansylcadaverine incorporation into casein. We studied the effect of different factors on the grafting: concentration and composition of the factor XIII preparation in the coupling solution and influence of the preactivation of factor XIII by thrombin. Stability studies have shown that the activity of factor XIII grafted on collagen membranes was almost constant over a period of 8 months. Sterilization by gamma-irradiation of factor XIII revealed a drastic loss of activity while the use of high-energized electron bombardment caused a reduced loss of activity. The potential of such a material for biomedical use is presently under investigation.
Congenital factor XIII deficiency is a rare hereditary disorder characterized by a marked tendency to bleeding. We describe a male newborn with inherited factor XIII deficiency. The patient was from a family without known antecedents and presented cephalohematoma as the first manifestation of the disease. This presentation is very unusual. The patient was diagnosed during the neonatal period and was successfully treated with substitution therapy. Early diagnosis and treatment of this disorder are important to prevent complications of severe bleeding.
Factor XIII is a proenzyme for a plasma transglutaminase. Factor XIII in plasma is a tetramer (A2B2) held together by noncovalent bonds, and the A subunit contains the active site. Recently, the three-dimensional structure of the A subunit has been determined by x-ray crystallography. To understand the structure-function relationships of the factor XIII molecule and its clinical implications in factor XIII deficiency, we characterized its genetic defects and closely examined its gene products, including mRNA and protein levels. A variety of missense and nonsense mutations (Arg260-Cys, Tyr283-Cys, Gly562-Arg) and deletions/insertions with or without out-of-frame shift/premature termination and splicing abnormalities (4-bp deletion with 464Stop, T insertion at the exon IV/intron D boundary with exon IV-skipping, 20-bp deletion at the exon I/intron A boundary) has been identified in cases demonstrating A subunit deficiency. In some cases, the A subunit mRNA levels were severely reduced. Their molecular and cellular bases have also been explored by expression experiments in mammalian cells and by molecular modeling. In most cases, impaired folding and/or conformational changes of the mutant A subunits lead to both intra- and extracellular instability, which is responsible for the A subunit deficiency in the patients.
Coagulation factor XIII (FXIII) is of paramount importance in the process of fibrin stabilization, which is the final step of the coagulation cascade. The clinical significance of defective fibrin stabilization is highlighted by the severe hemorrhagic manifestations of congenital FXIII deficiency. In this paper we review the pathophysiology, clinical presentation and therapy of acquired plasma FXIII deficiencies, caused by specific inhibitors or associated with other clinical conditions. For acquired severe FXIII deficiency caused by factor-specific inhibitors, the need for prompt diagnosis and treatment is emphasized by the high hemorrhagic risk and mortality. For moderate reduction of FXIII secondary to other conditions, we discuss the relative importance of FXIII reduction in the development of clinical symptoms and the role of substitution treatment.
Wound healing is far more rapid in the gastrointestinal tract than in the skin. Once dehiscence of a surgical anastomosis in the gastrointestinal tract occurs, the high collagenase activity in the gastrointestinal tract may delay wound healing and promote the formation of a nonhealing fistula. Because factor XIII promotes cross-linking of fibrin during the early phase of wound healing, we investigated the effect of factor XIII concentrate on 16 anastomotic leaks and a nonhealing fistula. A 240-U dose of factor XIII concentrate (Fibrogammin P) was administrated intravenously for 5 days. Factor XIII activity and plasma levels of epidermal growth factor (EGF), transforming growth factor (TGF)-beta, and interleukin-6 were measured before treatment and 1 day and 7 days after the end of treatment. Clinical outcomes were evaluated on the basis of the findings of contrast radiography, computed tomography, and drainage volume. Improvement relevant to the therapy was observed in 15 cases (88.2%). Factor XIII activity increased to more than 70% of the normal value in 11 cases (64.7%) but remained at 40% to 70% of the normal value in 6 cases (35.3%). Plasma EGF and TGF-betalevels increased in patients with improvement but were unchanged in patients without improvement. Our findings suggest that factor XIII significantly accelerates wound healing of anastomotic leaks and nonhealing fistulas by increasing circulating growth factors after systemic administration.
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Factor XIII A-chain-fibrin interactions regulate factor XIIIa formation and fibrin cross-linking. A microtiter plate assay was developed for studying these interactions. Microtiter plate wells were coated with fibrinogen and converted to fibrin by thrombin. After blocking the wells with bovine serum albumin, factor XIII A-chain was added and binding was monitored by incubating first with anti-factor XIII followed by anti-rabbit IgG-alkaline phosphatase. Enzymatic hydrolysis of p-nitrophenyl phosphate was quantitated by the absorbance at 405 nm. BInding was specific, sensitive, rapid, saturable, and reversible, requiring only nanograms of either factor XIII or fibrin. Binding was time- and concentration-dependent and independent of divalent cations. The bound material was identified as factor XIII A-chain by sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting. Factor XIII binding was inhibited > 75% by 250 mM sodium chloride or 250 nM anti-factor XIII IgG. The method was also suitable for demonstrating binding using 0.8% plasma or with r-factor XIII expressed in Saccharomyces cerevisiae or Escherichia coli. This method is suitable for identifying the binding sites that are important for plasma factor XIII activation and factor XIIIa activity.
Homozygous patients with factor XIII deficiency are devoid of immunologically identifiable A protein, the active enzymatic component. Quantitative studies of transamidase activity of the factor are available in only a few cases, and the fibrin cross-linking pattern is not well known. The present paper deals with the quantitative estimation of factor XIII transamidase activity (dansylcadaverine system), factor XIII molecular subunits, and the corresponding fibrin cross-linking pattern in seven homozygous patients with factor XIII deficiency. The results indicate that transamidase activity was present in all patients, and the range was 0.5-1.7%. The pattern of fibrin stabiisation showed an absence of cross-linking in two patients, the presence of gamma-gamma-dimers (traces) in four, and gamma-gamma-dimers plus incomplete alpha-polymers (traces) in one patient. In conclusion, the homozygous patients reported here were not completely devoid of functioning factor XIII.
Severe homozygous factor XIII deficiency was first described in Switzerland, in 1961. At present 14 patients are known here. Nine are of Swiss origin, the others are immigrants from eastern Europe. A 27-year-old woman with many haemorrhages during childhood immigrated to Switzerland and went through four episodes of haemorrhagic corpus luteum cyst rupture with life-threatening blood loss into the abdomen and three haemorrhages into the retroperitoneal muscles causing sensomotoric palsies, before the diagnosis was established. A monthly prophylactic replacement therapy of 500 IE factor XIII concentrate was started. Since then no signs of haemorrhage occurred. For the last trimester of pregnancy treatment intervals were shortened and dosage increased. Haemorrhage from the umbilical cord for weeks, subcutaneous haematomas, intracranial haemorrhage, muscle haemorrhage and wound bleeding with impaired wound healing as well as tendency to marked scar formation are characteristic for severe homozygous factor XIII deficiency. Without replacement therapy women suffer from obligate abortion. Diagnosis is made by the solubility of fibrin clots in urea (5 mol/l) or monochloroacetic acid (1-2%). For confirmation and monitoring of replacement therapy a quantitative incorporation assay is used. Replacement therapy is necessary in case of haemorrhage, injury, and surgery. Because of the high risk of intracranial haemorrhage prophylaxis is strongly recommended.
Purified plasma Factor XIII efficiently bound to the immobilized collagen affinity column. In contrast, when plasma was applied to the column, as much as 80% of Factor XIII was not trapped. It was shown that the difficulty of binding of Factor XIII in plasma to collagen is not due to the covering of collagen with some plasma proteins. We then assumed that Factor XIII formed a complex in plasma with a certain protein(s), which would prevent Factor XIII from binding to collagen. Using an immobilized Factor XIII affinity column, we have indeed obtained one protein from plasma with apparent Mr of 260,000.
Following application of factor XIII for 3 weeks bone healing was studied in Sprague-Dawley rats on the 20th postoperatively day qualitatively (radiographs, scintigraphy) and quantitatively (determination of callus thickness, of bone mineral content, and scintillation counting). No significant difference could be detected between animals treated with factor XIII and animals which served as controls. Therefore, a stimulating effect of factor XIII upon bone healing can not be expected in case of a normal factor XIII serum-level. The application of factor XIII is indicated only in high risk patients with a low factor XIII serum-level.
Human fibrin-stabilizing factor (Factor XIII) has been studied immunologically by the preparation of specific anti-Factor XIII antiserum in rabbits. On immunodiffusion it was found that normal plasma produced two precipitin lines. One of the precipitin lines was identical with that present in soluble platelet extract (the alpha-component), the other with that present in normal serum (beta-component). Plasma and serum of patients with congenital Factor XIII deficiency contained only the beta-component. By adsorption it was possible to prepare a second antiserum with solely anti-alpha-activity that did not react with the serum or plasma of XIII-deficient patients. Both antisera neutralized the clot-stabilizing activity of normal plasma. The action of thrombin on fibrinogen-free plasma or platelet extract abolished the immunoprecipitin alpha-line but did not reduce the capacity to neutralize antibody as measured by clot stabilization. It is concluded that the plasma Factor XIII molecule consists of two immunologically identifiable components, alpha and beta. The clot-stabilizing activity and thrombin-reactive site are situated on the alpha-component. Patients with congenital Factor XIII deficiency are devoid of immunologically identifiable or functional alpha-component but retain immunologically identifiable beta-component. It is this beta-component that accounts for the observed immunologically detectable Factor XIII in those patients devoid of clot-stabilizing activity.
Factor XIII has recently been recognized to play an important role as a fibrin-stabilizing factor to accelerate the wound healing process. We made an attempt to analyze the effect of how Factor XIII affects the results of the healing process at the site of a microvascular anastomosis. The strong fibrin stabilizing property of plasma Factor XIII maintained its high activity when administered intravenously and was effective for wound healing in a low-activity state made by subcutaneous administration of carbon tetrachloride. The enhanced network formation of the Factor-XIII-injected group was indicated by the accelerated maturation of the fibrin structure at the anastomotic site, exhibited both qualitatively and quantitatively. Stimulation and acceleration by Factor XIII of the healing process at the site of microvascular anastomosis were observed. It is therefore suggested that clinical use of Factor XIII may enhance the microvascular repair process. Details of the analysis using scanning electron microscopy (SEM) and a computerized graphic analyzer system (CGAS) are reported.