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At least 1,009 records · Page 56Linked to original sources
PubMed1992

Availability of the B beta(15-21) epitope on cross-linked human fibrin and its plasmic degradation products.

The binding of radiolabeled monoclonal antifibrin antibody 59D8 (specific for fibrin but not fibrinogen) to a series of degraded fibrin clots showed that the availability of the B beta(15-21) epitope (against which 59D8 had been raised) was inversely proportional to the extent of clot lysis. Examination of digest supernatants revealed that the B beta(15-21) epitope was released from clots as a high molecular weight degradation product in the presence of calcium ions but that the generation of low molecular weight peptides occurred in the absence of calcium ions. To address the question of epitope accessibility, we compared levels of fibrin clot binding among four radioactively labeled antibodies: antifibrin monoclonal antibody 59D8, two antifibrinogen monoclonal antibodies that cross-reacted with fibrin, and an affinity-purified polyclonal antifibrinogen antibody. We expected that the antifibrinogen antibodies would show enhanced binding to clots in comparison with the antifibrin antibody. However, the epitope accessibility experiments showed that all four antibody preparations bound fibrin clots at comparable levels. Taken together, these studies demonstrated that one fibrin-specific epitope, B beta(15-21), remains available on clots as they undergo degradation by plasmin and, importantly, that the epitope is not solubilized at a rate faster than the rate at which the clot is itself solubilized. The availability of the B beta(15-21) epitope during the course of plasminolysis assures the potential utility of antifibrin antibodies such as 59D8 for detecting thrombi and targeting plasminogen activators.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Inhibition of the process of Glu-plasminogen activation by tissue activator with fibrin, DDE-complex, and D-dimer using alpha-2-antiplasmin].

The alpha-2-antiplasmin influence on the Glu-plasminogen activation by tissue activator both on fibrin and fibrin(ogen) fragments was investigated. The kinetics of activation was studied and velocity of this process in the absence and presence of the inhibitor was calculated. It was established that alpha-2-antiplasmin decreased the velocity of Glu-plasminogen activation on desAABBfibrin, DDE-complex and DD-dimer and did no influence upon proenzyme activation on fibrinogen fragment--Ho1-DSK. In the presence of fibrin plasminogen activation linear related to the amount added tissue activator in limit concentration from 5 before 50 units/ml. It was shown that alpha-2-antiplasmin reduced the activation velocity with used concentration of tissue activator. Fibrin hydrolysis by plasmin, forming on its surface during the plasminogen activation by tissue activator, was also inhibited with alpha-2-antiplasmin. The obtained results are explained by the influence of the inhibitor on formation of the triple complex between plasminogen, tissue activator and fibrin, and competition of the alpha-2-antiplasmin for lysine-binding sites of tissue activator kringle 2 or for binding sites of the activator on fibrin.

Animals↗
PubMed1989

[Use of fibrin glue in surgery of parenchymatous organs].

The article discusses the results of one of the first studies conducted in the Soviet Union on the use of various types of fibrinous glue in operations on the parenchymatous organs. The data of 67 experiments on rabbits and 20 clinical cases are reported. The experiments were carried out to test the efficacy of fibrinous glue application for arresting parenchymatous bleeding and appraise the air-tightness of wounds of the liver, spleen, and kidney by the method of hydropressure with morphological control. The effect of fibrinous glue made of Soviet-produced components was also tested in experiment. In the clinic, fibrinous glue was used for arresting bleeding from wounds of the liver and spleen and for ensuring air-tightness of anastomoses and filling residual cavities after removal of hepatic cysts. The hemostatic effect of various types of fibrinous glue was found to be high both in experiments and in the clinic. Essential advantage over synthetic cyanoacrylate glues was proved. It was noted that the use of fibrinous glue in operations on the parenchymatous organs is promising.

Animals↗
PubMed1987

[The role of complementary E2 and D2 centers in the reaction between fibrin and fibrinogen].

The effect of fibrinogen on the two steps of polymerization of two fibrin forms differing in the set of polymerization sites (fibrin-desAA and fibrin-desAABB) was studied. It was shown that fibrinogen inhibited the protofibril growth and fibril formation at the stage of lateral aggregation more effectively with fibrin-desAABB than with fibrin desAA. When the fibrinogen D2-site was blocked by tetrapeptide Gly-His-Arg-Pro, the key structure of the E2-site, the inhibitory activity of fibrinogen diminished. A conclusion is drawn that the high susceptibility of fibrin-desAABB to fibrinogen is due to the interaction of the E2-active site with the D2-site of the fibrinogen molecule. The concentration dependence of the tetrapeptide Gly-His-Arg-Pro-induced inactivation of fibrinogen and the effects of temperature and Ca2+ on the tetrapeptide interaction with fibrinogen were investigated.

Fibrin↗
PubMedDate not supplied

[alphaC domains of fibrinogen molecules as the structures accelerating fibrin assembly].

Preparation of monomeric fibrin lacking intact alpha C-domains (monomeric X1-fragment), but fully clottable, is described. The assembly process of both monomeric fibrin and monomeric X1-fragment has been studied by electron microscopy and light scattering methods. It was shown that both proteins form similar fibrils with characteristic cross-banding. Upon dilution a sharp elevation of the differences between the assembly rates of monomeric X1-fragment and monomeric fibrin was revealed. The results obtained show that alpha C-domains take part in fibrin clot formation not as structural components but as the factor accelerating the ordered assembly of complex fibrin structure. The possible mechanism of alpha C-domains participation in fibrin clot formation are regarded.

Animals↗
PubMedDate not supplied

[Mechanism of self-assembly of soluble fibrin oligomers and the role of fibrinopeptides A and B in this process].

Three-dimensional organization of intermediate soluble forms of fibrin-polymers--a product of fibrin-monomer assembly--in the presence of non-denaturating urea concentrations has been studied. Hydrodynamic parameters of fibrinogen and fibrin-polymers were obtained by viscosimetry, dynamic light scattering and analytic ultracentrifugation. Using Yamakawa's hydrodynamic theory and considering fibrinogen molecule as an oblate ellipsoid of revolution made it possible to estimate the concentration effect on the coefficient of translational friction in the first, according to concentration, linear approximation. Hydrodynamic constants against polymer molecular weights were plotted using Swedberg's and Kuhn--Mark's equation. This made it possible to prove the existence of equilibrium single-stranded protofibrils formed by fibrin-monomer "end-to-end" association. It was concluded that local conformational transformations in fibrin-monomer molecule result in diminishing the complementarity of lateral binding sites; less specific D--D contacts remaining the only means of the "end-to-end" association. Experimentally obtained data give evidence that polymerization region is shifted towards much lower urea concentration, fibrinopeptide B being preserved. Therefore, the possibility of several conformational states of protein molecules during fibrinogen--fibrin transformation is discussed. It is supposed that changes in structure concern not only the central E-, but also the peripheral D- or alpha C-domains.

Animals↗
PubMed1984

Prevention of peritoneal adhesion formation by fibrin sealant. An experimental study in rats.

The preventive effect of rat and human fibrin sealing on intra-abdominal adhesion formation was investigated in 40 rats. Intraperitoneal adhesion formation was induced by excision of 1 X 3 cm of the peritoneal parietalmuscular layer, subsequently closed by interrupted 3-0 silk sutures. A total of 80 defects were allocated to one of four treatments: 1) the defect was covered with human fibrin sealant with the aid of a syringe. 2) the defect was covered with rat fibrin sealant with the aid of a syringe. 3) the defect was covered with human fibrin sealant with the aid of a spray. 4) the defect was not covered (control group). Assessment of the adhesion formation one week postoperatively showed that the median length of adhesions in defects covered with fibrin sealant applied by a syringe (10.5 mm) or by spray (14 mm) was less than that of the control group (25 mm) to a significantly high degree (P less than 0.001). It is concluded that fibrin sealant prevents intraperitoneal adhesion formation in the present rat model.

Animals↗
PubMed1978

[Fibrinogen and fibrin structure in patients with cirrhosis of the liver (author's transl)].

The question is still open, whether a pathologic formation of fibrinogen or an insufficient stabilized fibrin are causative factors within the complex disorders in hemostasis in patients with liver cirrhosis. Thus, 45 patients with liver cirrhosis, which was proven by liver biopsy, were investigated by means of sodium-dodecyl-sulfate (SDS) polyacrylamidgel-electrophoresis in order to evaluate, whether the liver produces a pathological fibrinogen or whether the formation of fibrin from fibrinogen is defect. The fibrin stabilizing factor (factor XIII) was measured by immunological methods. In order to have a mean of the stage of the disease, 37 patients were subdivided by the extend or their porto-caval collateral circulation and further 8 patients were investigated having bleeding from esophageal varices. By the results evidence accrued that in advanced stages of liver cirrhosis and a marked porto-caval collateral circulation polymerization of fibrinogen was insufficiently, especially, the formation of alpha-chains was altered, whereas the formation of gamma-dimers, the separation of fibrinopeptides from fibrinogen, and the aggregation of fibrinmonomers were normal. This defect in fibrin structure was positive correlated with the stage of liver cirrhosis, which correlated negative with the plasma activity of factor XIII. In vitro, the defect in fibrin formation, from fibrinogen was abolished by adding factor XIII to the assay. Thus, in liver cirrhosis fibrin formation is altered because of factor XIII deficiency, but a normal fibrinogen is synthesized by the liver. In consequence, the administration of factor XIII preparations is suggested as one clinical action among others to benefit the hemostatic disorders, especially in patients with bleeding from esophageal varices.

Blood Coagulation Disorders↗
PubMed1991

Inhibition of intraocular fibrin formation following infusion of low-molecular-weight heparin during vitrectomy.

We studied the inhibition of intraocular fibrin formation following infusion of 5 IU/mL of low-molecular-weight heparin sodium (Fragmin, KabiVitrum AB, Stockholm, Sweden) during lensectomy, vitrectomy, and retinotomy in the rabbit model. Surgery was performed on 18 eyes, with nine receiving low-molecular-weight heparin and nine serving as controls. Masked postoperative examinations assessed fibrin quantity, corneal clarity, media clarity, and amount of vitreous hemorrhage. Five (56%) of nine eyes receiving low-molecular-weight heparin did not show fibrin exudation development, with the remainder demonstrating a minimal fibrin response. Eight (89%) of nine control eyes demonstrated prominent fibrin exudation, with five (56%) showing development of a fibrin clot that obscured two or more quadrants of the posterior chamber. No significant difference in the degree of vitreous hemorrhage was noted between groups. Corneal clarity was improved in the heparin-treated group.

Animals↗
PubMed2004

Comparison of a new fibrin sealant with standard topical hemostatic agents.

BACKGROUND: Bleeding following liver resection continues to be a significant morbidity of the procedure. Fibrin sealants represent an improvement over conventional topical hemostatic agents, because they contain components that actively form clot. However, most available agents contain nonhuman protein, which represents an immunologic risk. HYPOTHESIS: An investigational surgical fibrin sealant (Crosseal; American Red Cross, Washington, DC) composed of human clottable proteins and human thrombin is more effective than standard topical hemostatic agents in reducing the time required to achieve hemostasis after liver resection. DESIGN: Prospective, randomized, controlled trial. SETTING: Fifteen major referral centers in the United States and the United Kingdom. METHODS: After liver resection using standard surgical techniques, 121 patients seen between May 1999 and May 2000 were randomized to treatment with a 2-component fibrin sealant (n=58) or to standard topical hemostatic agents, used singly or in combination (n=63). Up to 10 mL of Crosseal was administered by a spray applicator, as recommended by the manufacturer, whereas agents used in the control group were applied according to their instructions for use. MAIN OUTCOME MEASURES: The primary outcome measured was time to hemostasis. Secondary outcomes measured included blood loss between application of the hemostatic agent and closure of the abdomen, duration of postoperative biliary drainage, and the occurrence of complications, defined a priori as reoperation for any reason, development of abdominal fluid collections, or bilious appearance of drained fluid for at least 1 day postoperatively. RESULTS: The mean time to hemostasis was 282 seconds with Crosseal, compared with 468 seconds with standard agents (2-sided; P =.06), for the 116 efficacy-evaluable patients. Hemostasis was achieved within 10 minutes in 53 patients (91.4%) treated with the study fibrin sealant and in 44 control patients (69.8%) (2-sided; P =.003). Intraoperative blood loss was similar in the 2 groups. In the Crosseal group, the percentage of patients developing postoperative complications was 17.2%, compared with 36.5% in the control group (2-sided; P =.02). CONCLUSIONS: Compared with the use of standard topical hemostatic agents, Crosseal fibrin sealant significantly reduced the time to achieve hemostasis following liver resection. Patients treated with the new fibrin sealant also experienced significantly fewer postoperative complications.

Adult↗
PubMed1999

Plasmin degradation of fibrin coatings on synthetic polymer substrates.

The goal of this research was to evaluate the in vitro stability of fibrin coatings on polymeric materials in the presence of plasmin. Factor XIIIa-crosslinked and noncrosslinked fibrin layers were coated on three different polyurethane substrates: Corethane, Tegaderm, and a biodegradable polyurethane, PCL/HDI/Phe. Degradation assays indicated that crosslinking the fibrin coatings enhanced the stability of the coatings on both Tegaderm and PCL/HDI/Phe; however, the persistence of the coating on the woven Corethane was not influenced by crosslinking. Degradation assay results also showed that the fibrin coating on the Corethane was significantly less stable than the fibrin coatings on the Tegaderm and PCL/HDI/Phe films. The chromogenic substrate assay data showed crosslinking did not affect the specific plasmin activity on the coatings; therefore, the increased stability resulting from crosslinking was not achieved through a reduction of fibrinolysis. The plasmin activity on the coated Corethane samples was much greater than that on either of the coated flat wound dressing materials. The large surface area of Corethane, a porous woven vascular graft material, may have had a direct influence on the fibrinolysis of its coatings by providing a large number of tissue-type plasminogen activator (tPA) binding sites. A thin, crosslinked, fibrin-coated polyurethane provides a theoretically attractive biomaterial for use in a wound dressing application and should be subject to ongoing research.

Chromogenic Compounds↗
PubMed1988

Phorbol ester stimulates macrophage invasion of fibrin matrices.

Macrophages migrate through a fibrin-rich extracellular matrix in chronic inflammation, wound healing, and other pathophysiological processes. To investigate the factors that might influence the ability of mononuclear phagocytes to invade fibrin matrices, we cultured macrophage-like P388D1 cells as well as resident and thioglycollate-elicited mouse peritoneal macrophages on three-dimensional fibrin gels, and we examined the effect of agents known to stimulate a variety of macrophage functions, including the production of fibrinolytic enzymes. Cells grown on fibrin gels under control conditions, as well as cells treated with either bacterial lipopolysaccharide or concanavalin A, remained confined to the gel surface. In contrast, the tumor promoter 4 beta-phorbol 12-myristate 13-acetate (PMA) induced both P388D1 cells and peritoneal macrophages to invade the underlying fibrin matrix. The invasive behavior of PMA-treated P388D1 cells was not affected by protease inhibitors of various specificities. These results demonstrate that certain exogenous signals can profoundly modify the ability of macrophages to migrate through fibrin matrices.

Animals↗
PubMed2002

Fibrin as an alternative biopolymer to type-I collagen for the fabrication of a media equivalent.

We report here on studies examining the use of fibrin as an alternative to collagen for the entrapment of neonatal aortic rat smooth muscle cells (SMCs) in the fabrication of media equivalents. The studies show increased collagen production by fibroblasts entrapped in fibrin, which suggests that fibrin may be used in the fabrication of tissue equivalents to promote increased protein synthesis and remodeling. However, one of the challenges of working with fibrin is the rapid degradation by SMCs. This degradation was effectively inhibited with the addition of epsilon-aminocaproic acid (EACA) to the culture medium in concentrations ranging from 0.25 to 1 mg/mL. We also present results showing that fibrin stimulates collagen production by SMCs. SMCs in fibrin produced 3.2 and 4.9 times the amount of collagen produced by SMCs in collagen when supplemented with 1 and 0.25 mg/mL EACA, respectively. More than half of the collagen produced appeared in the medium rather than the matrix. The collagen in the medium appeared to be processed beyond the proform and may be in an aggregate form. In addition, the presence of type-III collagen or a type-I trimer was indicated by the results of an analysis of the medium by autoradiography.

Aminocaproic Acid↗
PubMed2002

Failure characteristics of multiple-component fibrin-based adhesives.

A series of analyses were performed on fibrin-based adhesives to describe their failure characteristics. Two test methods were used: uniaxial, monotonic tensile testing of the bulk material, and blister testing using fresh porcine-source skin graft as the adherend. Two fibrin concentrations, high (HFC), and low (LFC), were used to investigate the effects of the gel matrix density upon mechanical properties. In tensile tests, fibrin gels strain hardened, as functions of percent strain and of strain rate. An increase in modulus of elasticity (E) was seen with increasing strain and strain rate at both tested fibrin concentrations. Mode I failure mechanisms were predominant. Both adhesives appeared to fracture from the outer edge to the interior of the specimen at slower strain rate tests. This trend reversed as strain rate increased, becoming a classic "cup and cone" ductile fracture. Syneresis occurred at both concentrations at lower strain rates, but was more pronounced for the LFC. Ultimate tensile strength and E were greater for the HFC than for the LFC at all strain rates, decreasing with increasing strain rate. In the blister test, the failure locus changed from cohesive to adhesive as the strain rate was increased for the HFC. Failure of fibrin gels likely occurs by percolation of the pressurized saline, displacing the entrapped liquid phase of the gel in regions of relatively low moduli and strength, leading to fracture of the matrix. For LFC, the overall fracture locus remained predominantly cohesive regardless of strain rate. Burst strength and failure energy were higher for HFC than for LFC. It would appear that fibrin acts more as a viscous liquid than a rubberlike/elastic material at lower concentrations because adhesive failures had a higher burst strength and fracture energy (Gc) than did cohesive failures.

Animals↗
PubMed1990

Apatite--wollastonite containing glass ceramic granule-fibrin mixture as a bone graft filler: use with low granular density.

The purpose of this study was to investigate bone formation after implantation of a mixture of apatite--wollastonite containing glass ceramic granules (A-W.GC, 220-355 microns) and fibrin glue with a low A-W.GC granular density. The fibrinogen was prepared from rat blood plasma. A mixture of A-W.GC granules and fibrin glue 1:4 in volume ratio (1:4 mixture) was implanted in the proximal metaphysis of the rat tibia, and bone formation was evaluated quantitatively by histomorphometry in undecalcified specimens. Microangiography was performed in animals sacrificed 5 days after the operation. The results were compared with those of a previous study in which a 1:1 mixture of A-W.GC granules and fibrin glue was used. With the 1:4 mixture, the A-W.GC density was 39.7% because of concentration of fibrin at packing. Good early vascularization comparable to that after implantation of the 1:1 mixture was observed. Bone formation proceeded at the same rate as after implantation of 1:1 mixture, but the level of the plateau was higher than that for the 1:1 mixture. The osteoconductive potential of the 1:4 A-W.GC-fibrin mixture was similar to that of the 1:1 mixture, and was higher than that of A-W.GC without fibrin.

Animals↗
PubMed1992

Mechanical properties of fibrin adhesives for blood vessel anastomosis.

Various methods have been used for anastomosing, or attaching, two ends of a severed blood vessel together. The most common method, suturing, is tedious, can be time-consuming, and requires special training in microvascular surgery. Other methods, such as mechanical devices and lasers, have some problems as well. The use of fibrin adhesives for blood vessel anastomosis might eliminate some of the current problems by allowing a quicker, simpler, and more reliable method of attachment. Although mechanical studies have been conducted to determine fibrin glue properties in shear, tensile, and burst tests; most of these studies have used skin or intestinal tissue. Therefore, to evaluate the feasibility of using fibrin glue as an adhesive for blood vessel anastomosis, the mechanical properties of blood vessels joined with fibrin glue were examined using tensile and burst tests. High and low fibrinogen concentrations were tested after 5- or 45-min time periods. In addition, three clinical methods of attachment were compared: end-to-end anastomosis, vessel overlapping, and suturing. In this study, because the adhesive strength was not found to increase significantly after 5 min, setting times for fibrin glue may be short enough to make it a clinical option when compared to suturing. In addition, the higher fibrinogen concentration did not result in a significantly higher adhesive strength, indicating that the lower concentration fibrin adhesives may be of comparable strength to the higher concentrations for clinical applications.

Anastomosis, Surgical↗
PubMed2004

The effect of tranexamic acid in fibrin sealant on adhesion formation in the rat.

The objective of the research was to determine the effect of the type, dose, and volume of anti-fibrinolytic agents (tranexamic acid, aprotinin) added to fibrin formulations, on adhesion development. Adhesions were induced in 228 male rats by creating apposing parietal and visceral peritoneal defects. Animals were randomized to receive no treatment or a fibrin formulation containing aprotinin or tranexamic acid. Seven days later the incidence of adhesions, and the force and energy required to detach them, were determined. Adhesions developed in 13/13 rats in the control and aprotinin groups. Treatment with fibrin (100 mg/ml tranexamic acid) resulted in adhesions in 4/14 rats (as strips, p < or = 0.0005), 4/10 rats (as spray, p < or = 0.0036), and 12/15 rats (by drip). The reduction of adhesions was dependent on the concentration of tranexamic acid with strip and spray application. Using commercial formulations, tranexamic-acid-containing fibrin (10/15, p = 0.042), but not aprotinin-containing fibrin (13/15), reduced the incidence of side-wall adhesions from 15/15 in controls. Fibrin containing either tranexamic or aprotinin reduced the incidence and severity of adhesions. This effect was greater when tranexamic acid was used and was dependent on the mode of administration, the volume, and to a degree, the concentration of tranexamic acid.

Animals↗
PubMed2005

Autologous fibrin glue in peripheral nerve regeneration in vivo.

The activity of several growth factors on peripheral nerve regeneration is reported. Autologous fibrin glue contains a large number of platelets, which release significant quantities of growth factors. In order to understand the role of autologous fibrin glue in peripheral nerve regeneration, a 15-mm rabbit peroneal nerve defect was repaired using a vein graft filled with autologous fibrin glue. Axonal regeneration was examined using histological and electrophysiological methods. The extent of axonal regeneration was superior when treated with autologous fibrin glue. Our data suggest that fibrin nets formed by fibrinogen, in combination with growth factors present in autologous fibrin glue, might effectively promote peripheral nerve regeneration in nerve defects.

Animals↗