Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FIBRIN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1987

Factor XIIIa formation promoted by complexing of alpha-thrombin, fibrin, and plasma factor XIII.

Fibrin polymers (des A,B fibrinogen) reduced the concentration of alpha-thrombin required for 50% activation of plasma factor XIII (a2b2 tetramer) by approximately 100-fold. In the presence of fibrin, the amount of gamma-thrombin required for activation was not affected. Catalytically inactive i-Pr2P- and D-Phe-Pro-Arg-CH2-alpha-thrombin were found to inhibit over 95% of the activation by alpha-thrombin in the presence of fibrin. Unlike plasma factor XIII, the concentration of alpha-thrombin required for 50% activation of platelet factor XIII (a2 dimer) was lower, and the activation was not enhanced by fibrin. However, when the a2 platelet factor XIII was incubated with purified b-chains, the alpha- and gamma-thrombin concentrations required for activation increased tenfold and reached levels similar to those required for activation of the plasma factor XIII. When fibrin was present, the alpha-thrombin concentrations needed for activation of the a2b2 complexes were reduced, and the presence of fibrin had no effect on gamma-thrombin cleavage of the a2b2 complexes. Therefore, the b-chains must inhibit a-chain cleavage by alpha-thrombin in the absence of fibrin. These results imply that the formation of a cocomplex involving alpha-thrombin, fibrin, and plasma factor XIII causes some conformational change in plasma factor XIII such that the b-chains no longer inhibit cleavage of the a-chains.

Factor XIII↗
PubMed1988

Fibrin-specific thrombolytic agents.

The fibrinolytic system comprises a proenzyme, plasminogen, which can be converted to the active enzyme plasmin, which will degrade fibrin. Plasminogen activation is mediated by plasminogen activators which are classified as either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Inhibition of the fibrinolytic system may occur at the level of the activators or at the level of generated plasmin. Plasmin has a low substrate specificity and when circulating freely in the blood will degrade several proteins including fibrinogen, Factor V and Factor VIII. Plasma does, however, contain a fast-acting plasmin inhibitor, alpha 2-antiplasmin, which will inhibit free plasmin extremely rapidly (t1/2: 0.1 s) but which reacts much slower (10(3)-fold) with plasmin bound to fibrin. A "systemic fibrinolytic state" may, however, occur by extensive activation of plasminogen (conc. in plasma 2 microM) and depletion of alpha 2-antiplasmin (conc. in plasma 1 microM). Clot-specific thrombolysis therefore requires plasminogen activation restricted to the vicinity of the fibrin. Two physiological plasminogen activators, t-PA and single-chain u-PA (scu-PA) induce clot-specific thrombolysis, however via entirely different mechanisms. t-PA is relatively inactive in the absence of fibrin, but fibrin strikingly enhances the activation rate of plasminogen by t-PA. This is explained by an increased affinity of fibrin-bound t-PA for plasminogen and not by alteration of the catalytic rate constant of the enzyme. The high affinity of t-PA for plasminogen in the presence of fibrin thus allows efficient activation on the fibrin clot while no significant plasminogen activation by t-PA occurs in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Orientation and specificity of fibrin protofibril binding to ADP-stimulated platelets.

We have investigated the molecular basis of platelet:fibrin binding by studying interactions between platelets and protofibrils, soluble two-stranded polymers of fibrin, which are intermediates on the fibrin assembly pathway. The specificity of these interactions was examined with transmission electron microscopy (TEM), which clearly showed thin fibers with lengths to 150 nm attached to the cell surface of normal, stimulated platelets. Immunogold electron microscopy using rabbit anti-human fibrinogen as the first stage antibody verified the identity of the surface-bound molecules, and the immunogold distribution paralleled that observed with the fibrin/fibrinogen molecules alone. Contacts between the ends of the fibers and the platelets were frequently observed, but lateral contacts were also evident. Given the diameter at the point of fibrin contact (18.2 +/- 1.3 nm), it is possible that several glycoprotein receptors were involved in binding each protofibril. Morphometric analyses demonstrated that normal platelets stimulated by ADP in the absence of exogenous fibrin(ogen) or in the presence of fibrin protofibrils and antibodies directed against the GPIIb/IIIa complex lacked this molecular layer on the surface. Neither protofibrils nor fibrin fibers adhered to the surface of Glanzmann's thrombasthenic platelets, as demonstrated by TEM and microfluorimetry. Synthetic peptides of sequence RGDS and HHLGGAKQAGDV effectively blocked the binding of protofibrils to the surface of normal, stimulated platelets while synthetic GHRP had no effect. These results provide direct evidence for multiple points of attachment between fibrin protofibrils and the glycoprotein IIb/IIIa complexes present in a functional conformation on the surface of normal, stimulated platelets.

Adenosine Diphosphate↗
PubMed1988

Fibrinogen influx and accumulation of cross-linked fibrin in mouse carcinomas.

125I-radiolabeled guinea pig fibrinogen was used to measure the influx (20 min) and accumulation (18 h) of fibrinogen/fibrin in three transplantable carcinomas (Lewis lung, TA3/St mammary, and MOT ovarian) growing in the subcutaneous space of syngeneic mice. Fibrinogen influx and, to an even greater extent, fibrin accumulation were substantially increased in all three tumors, as compared with normal control tissues. A significantly larger fraction of tumor-associated than control tissue radioactivity was insoluble in 3 M urea, a property of cross-linked fibrin. Positive identification of cross-linked fibrin was made by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of tumor extracts. Tumor fibrin deposits were localized by immunoperoxidase staining of tissue sections. Fibrin accumulation was also significantly increased in premalignant hyperplastic alveolar nodules that had been transplanted to cleared mammary fat pads, as compared with normal mammary tissue, and was further increased in primary mammary carcinomas that arose from hyperplastic alveolar nodules. These findings generalize to the mouse the principles that tumor vessels are hyperpermeable to plasma proteins and that fibrin accumulates in transplantable and primary tumors. Further, they demonstrate that tumor fibrin is cross-linked and therefore analogous to the fibrin deposited in thrombi, wounds, and cellular immunity.

Animals↗
PubMed1988

Role of fibrin coagulation in protection of murine tumor cells from destruction by cytotoxic cells.

We have previously proposed that fibrin deposition on tumor cells during their migration in the blood could protect them from elimination by natural killer (NK) or other cytotoxic cells. Anticoagulant drugs could prevent fibrin coagulation and increase the efficiency of cytotoxic effector cells in tumor cell elimination. To further investigate the protective roles of fibrin, we studied in vitro the susceptibility of various murine tumor cells to the cytotoxic activity of NK or lymphokine activated killer (LAK) cells in the presence of murine plasma or serum. In the first set of experiments, tumor cells were incubated with plasma (at dilutions of 1:20-1:160) for 30 min before effector cells were added. Similarly, effector cells were first incubated with plasma before mixing with radiolabeled target cells for cytotoxicity assay. In some experiments target and effector cells and plasma were mixed simultaneously. The cytotoxic activity of both NK and LAK cells was inhibited if coagulation occurred around tumor-target or effector cells. Tumor cells were also protected when both target and effector cells were simultaneously mixed and trapped in the fibrin clot. Inhibition of the cytotoxic activity of effector cells against tumor cells was positively correlated with the level of fibrin clot formation. When the larger clot was formed and more radiolabeled tumor cells were trapped in the clot, the higher level of inhibition of cytotoxicity was observed. In contrast, serum did not affect the cytotoxic activity of NK or LAK cells. To exclude possible non-coagulation-related effects of plasma on LAK cells, a cytotoxicity series of experiments was performed using purified fibrinogen and thrombin. When fibrinogen and thrombin were preincubated with tumor cells or LAK cells or all components were admixed simultaneously, substantial protection of tumor cells from destruction by LAK cells was also observed. However, when heparin was added, fibrin coagulation was prevented and cytotoxic activity of LAK cells was restored. Inhibition of LAK cytotoxicity and protection of tumor cells by fibrin coagulation were mostly due to the prevention of tumor-effector cell conjugate formation. Adding plasma at postbinding time periods (15-30 min after mixing effector and target cells) did not affect the ability of LAK cells to kill tumor cells confirming that fibrin coagulation influenced the binding rather than the lytic phase of cytotoxic cell activity.

Animals↗
PubMed1987

Fibrin monomer induces binding of endogenous platelet von Willebrand factor to the glycocalicin portion of platelet glycoprotein IB.

This study demonstrates that when platelets are stimulated by thrombin in the presence of low concentrations of purified human fibrinogen (10 to 20 micrograms/mL, final concentration) binding of released platelet von Willebrand factor (plt-vWF) to the platelet membrane is enhanced. This effect appears to be mediated by fibrin monomer produced by the action of thrombin on the fibrinogen in the incubation suspension. When fibrin polymerization is inhibited, the binding of released plt-vWF to the platelets is markedly increased. This enhanced binding is dependent on platelet glycoprotein Ib (GPIb) as shown by a decreased response with Bernard-Soulier platelets and inhibition by both monoclonal and polyclonal antibodies against glycocalicin. The binding of fibrin to thrombin-activated platelets preincubated with monoclonal antibody against GPIIb/IIIa is increased when the predominant form of fibrin is fibrin monomer. The fibrin binding is also decreased in the presence of antibody against glycocalicin. Our data demonstrate that fibrin monomer facilitates plt-vWF binding to the glycocalicin portion of platelet GPIb on thrombin-stimulated platelets and that binding of fibrin monomer to glycocalicin is necessary for this response to occur.

Blood Platelets↗
PubMedDate not supplied

[Interaction of an analog of the E1 site of tetrapeptide Gly-Pro-Arg-Pro with the D1 site of two forms of monomeric fibrin].

Two monomeric fibrin forms differing in a set of polymerization sites (fibrin desAA and fibrin-desAABB) are inhibited to a different extent by tetrapeptide Gly-Pro-Arg-Pro which simulates a moiety of polymerization site E1. The lesser sensitivity of fibrin-desAABB polymerization to the inhibiting tetrapeptide is due to the presence of active site E2 in it. A shape of the concentration dependence curve of the inhibitory effect of tetrapeptide Gly-Pro-Arg-Pro on the polymerization of both fibrin types is similar to the previously found curve for fibrinogen and its fragments--specific inhibitors of polymerization. Ca2+ intensifies inhibition of fibrin-desAABB polymerization by tetrapeptide Gly-Pro-Arg-Pro twice as much as that of fibrin-desAA evidently due to the peptide blockage of sites D2. An increase of the ionic strength from 0.15 to 0.3 enhances the inhibitory effect of the tetrapeptide on polymerization of two monomeric fibrin forms.

Animals↗
PubMed1986

Effects of thrombospondin on fibrin polymerization and structure.

Thrombospondin (TSP) is a trace protein in plasma but is released in high concentrations from alpha-granules of activated platelets during hemostasis. It binds to the platelet membrane and becomes incorporated into fibrin clots. A variety of approaches were taken to learn the effects of TSP on fibrin polymerization and structure. 125I-TSP and 125I-fibrinogen were used to study the effect of TSP concentration on the extent of TSP and fibrin incorporation. Turbidity at 600 nm was used to monitor the time course of polymerization. Wavelength dependence of the turbidity was used to calculate the mass to length ratio, fiber diameter, and fiber density of fibrin formed in the presence and absence of TSP. Morphologies of control and TSP-containing clots were examined by electron microscopy following critical point drying. The initial TSP concentration influenced the amount of TSP incorporated but did not alter the extent of fibrin polymerization. TSP, in a concentration-dependent manner, reduced the lag time to turbidity rise and caused formation of more numerous but thinner fibers. Except for their diameter, these fibers were identical to fibers of control fibrin in terms of density and morphology. It is proposed that TSP interacts with fibrin intermediates to accelerate fiber growth, perhaps by serving as a trifunctional branching unit during network formation. The properties of fibrin around aggregating platelets, therefore, may be influenced considerably by secreted TSP.

Blood Platelets↗
PubMed1985

Fibronectin binding to thrombin-stimulated platelets: evidence for fibrin(ogen) independent and dependent pathways.

Plasma fibronectin binds in a specific and saturable manner to thrombin-stimulated platelets. gamma-Thrombin stimulated 80% as much fibronectin binding to platelets as alpha-thrombin with conversion of less than or equal to 1% of platelet fibrinogen to fibrin. Afibrinogenemic and normal platelets bound similar quantities of fibronectin in the presence of calcium or magnesium-ethylene glycol tetra-acetic acid (EGTA). These observations indicate that fibronectin can interact with platelets without involvement of fibrin or fibrinogen. Nevertheless, two different effects of fibrin(ogen) on fibronectin binding were observed. First, exogenous fibrinogen inhibited fibronectin binding to thrombin-stimulated platelets. This inhibition was unidirectional, as fibronectin did not inhibit fibrinogen binding to ADP or thrombin-stimulated cells. Second, formaldehyde-fixed cells with surface-associated fibrin bound significant quantities of fibronectin. This interaction required calcium and did not occur on fixed cells with or without surface-bound fibrinogen. A portion of the ligand bound to fixed cells with surface-associated fibrin was modified to form a derivative with a molecular weight identical to that of the fibronectin subunit cross-linked to the alpha-chain of fibrin. This high mol wt derivative was also observed to a variable extent with living cells in the presence of magnesium or calcium but not in the presence of magnesium-EGTA. Thus, fibronectin binds to platelets by at least two mechanisms: (1) a fibrin(ogen)-independent pathway that requires divalent ions and is inhibited by exogenous fibrinogen; and (2) a fibrin-dependent pathway with an absolute calcium requirement. With nonaggregated, thrombin-stimulated platelets, the former pathway appears to predominate.

Adenosine Diphosphate↗
PubMed1983

Thrombin activity of fibrin thrombi and soluble plasmic derivatives.

Fibrin was prepared from purified fibrinogen, plasma, and pathologic arterial thrombi and assayed for thrombin activity. Activity was detected on fibrin from each of these sources when assayed by three techniques: the rate of release of FPA from fibrinogen, a clotting time assay, and the rate of hydrolysis of the chromogenic substrate S-2238. Of the labeled thrombin initially associated with fibrin during clot formation in vitro, all but 10% to 15% could be removed easily by manual compression or by incubation in buffer. Radiolabeled thrombin that remained bound to clots of purified fibrinogen retained full functional activity, whereas that bound to plasma clots expressed only 4% of expected activity. Plasmic lysis of fibrin from clots of purified fibrinogen released bound thrombin quantitatively into solution in active form. The solubilized thrombin retained association with specific macromolecular fibrin derivatives as demonstrated by sedimentation analysis, electrophoretic co-migration, and partitioning in agarose gel. Plasmic lysates of fibrin prepared in vitro from plasma or pathologic arterial clots also expressed thrombin activity, in an amount similar to the fibrin from which they were prepared. Our studies demonstrate the presence of functionally active thrombin on fibrin prepared from in vitro clots and in vivo thrombi as well as in association with soluble plasmic derivatives of these substrates. This activity may constitute a prothrombotic influence and may contribute to the elevated FPA-levels seen in patients with thrombotic disease.

Blood Coagulation↗
PubMed1983

Interactions between fibrin and the plasminogen activators produced by cultured endothelial cells.

Serum-free conditioned medium (CM) from cultured bovine aortic endothelial cells (BAEs) was fractionated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and analyzed for plasminogen activator (PA) activity by fibrin autography. Distinct size forms of PA with molecular weights (mol wt) of 100,000, 74,000, and 52,000 were readily identified by this approach. When fibrinogen and thrombin were added to CM containing these forms, approximately 55% of the total activity was found to associate with the resultant fibrin clot. The other 45% remained free in the supernatant. This relationship did not change at higher fibrin concentrations. Subsequent analysis revealed that only the larger PA forms (mol wt 74,000-100,000) were recovered in the clot. The 52,000 form did not bind to the polymerizing fibrin under these conditions. The fibrin-binding forms also bound to immobilized concanavalin-A and could be separated from those forms that did not interact with fibrin by concanavalin-A affinity chromatography. The PA activity of the separated forms was then compared by assessing their ability to cleave 125I-plasminogen. Although cleavage by the 52,000 mol wt form was apparent, little if any cleavage was initiated by the mixture containing the 74,000-100,000 forms. The addition of fibrin to this sample resulted in the generation of a potent PA activity. These results indicate that cultured BAEs produce multiple forms of PA that differ both in size and in behavior toward fibrin and concanavalin-A. These forms include molecules that functionally and immunochemically resemble human urokinase, and others that resemble human tissue-type PA.

Animals↗
PubMed1982

Effect of calcium and synthetic peptides on fibrin polymerization.

Human fibrinogen was subjected to limited proteolytic attack by thrombin, batroxobin or Agkistrodon contortrix thrombin-like enzyme, yielding desAB-, desA- or desB-fibrin monomers, respectively. Turbidity curves demonstrated that, with all three enzymes, the polymerization process was strongly accelerated by increasing the calcium concentration from 10(-5) M to 10(-4) M. Synthetic peptide Gly-His-Arg (5 mM), an analogue of the aminoterminal sequence of fibrin beta-chain, inhibited aggregation of desB-fibrin monomers at physiological calcium concentration whereas it enhanced aggregation of desA- and desAB-fibrin monomers at calcium concentrations below 10(-4) M. On the other hand, Gly-Pro-Arg (1 mM) corresponding to the amino-terminus of fibrin alpha-chain, dramatically inhibited aggregation of both desA- and desB-fibrins, but it only moderately affected the polymerization of thrombin-induced monomers. We conclude that the observed effects of Gly-Pro-Arg and Gly-His-Arg are not due solely to their competition with fibrin amino-termini for the respective binding sites in the D-domain, but rather reflect conformational changes in fibrin monomers which affect the polymerization process.

Batroxobin↗
PubMed1995

Regulation of fibrin deposition by malignant mesothelioma.

Malignant mesothelioma (MM) is a locally aggressive tumor that spreads by poorly understood mechanisms. Because neoplastic spread has been linked to altered fibrin turnover, we used immunohistochemistry of nine MM and three fibrous tumors of the pleura to confirm in vivo fibrin deposition and expression of selected coagulation and fibrinolytic reactants in MM. Tumor-associated fibrin was readily detectable at site of tissue invasion. Little fibrin was distributed within the tumor, but tissue factor and tissue factor pathway inhibitor, urokinase, urokinase receptor, and plasminogen activator inhibitors 1 and 2 were all detected in either epithelioid or sarcomatous areas of MM. We used the MS-1 human pleural mesothelioma cell line to determine how expression of these reactants is regulated. Fibrinolytic activity of MS-1 is mainly due to urokinase and is responsive to cytokine stimulation. Functional extrinsic activation and prothrombinase complexes assemble at the cell surface. MM express procoagulants as well as fibrinolytic reactants in vivo and in vitro that promote local fibrin formation and remodeling. Fibrin deposition occurs primarily at areas of tissue invasion and could promote local extension of this neoplasm. Sparsity of fibrin within the central portions of the tumor stroma suggests that local resorption of transitional fibrin occurs at sites of established MM.

Blood Coagulation↗
PubMed1995

Alpha-Chain cross-linking in fibrin(ogen) Marburg.

The fibrinogen structural variant, Marburg (A alpha 1-460B beta gamma)2, is comprised of normal B beta and gamma chains but contains severely truncated A alpha chains that are missing approximately one half of their factor XIIIa cross-linking domain. Immunochemical studies of fibrin(ogen) Marburg were conducted to characterize the degree to which deletion of a defined A alpha-chain segment, A alpha 461-610, can affect the process of fibrin stabilization, ie, the factor XIIIa-mediated covalent interaction that occurs between alpha chains of neighboring fibrin molecules and between alpha chains and alpha 2 antiplasmin (alpha 2PI). The ability of Marburg (and control) alpha chains to serve as a substrate for factor XIIIa and undergo cross-linking was examined in an in vitro plasma clotting system. The capacity for alpha-chain cross-linking was evaluated both as the covalent incorporation of the small synthetic peptide, NQEQVSPLTLLK (which represents the first 12 amino acids of alpha 2PI and includes the factor XIIIa-sensitive glutamine residue responsible for the cross-linking of alpha 2PI to fibrin), and as the appearance of native (ie, natural), high-molecular-weight, cross-linked alpha-chain species. Antibodies specific for the (A)alpha and gamma/gamma-gamma chains of fibrin(ogen) and for the peptide and its parent protein, alpha 2PI (68 kD), were used as immunoblotting probes to visualize the various cross-linked products formed during in vitro clotting. Recalcification of Marburg plasma in the presence of increasing concentrations of peptide resulted in the formation of peptide-decorated Marburg alpha-chain monomers. Their size at the highest peptide concentration examined indicated the incorporation of a maximum of 3 to 4 mol of peptide per mole of alpha-chain. In the absence of alpha 2PI 1-12 peptide, the alpha chains of Marburg fibrin cross-linked to form oligomers and polymers, as well as heterodimers that included alpha 2PI. Both the peptide-decorated monomers and the native cross-linked alpha-chain species of Marburg fibrin were smaller than their control plasma counterparts, consistent with the truncated structure of the parent Marburg A alpha chain. Collectively, the findings indicate that, although deletion of the A alpha chain region no. 461-610 in fibrinogen Marburg prevents formation of an extensive alpha polymer network (presumably due to the absence of critical COOH-terminal lysine residues), it does not interfere with initial events in the fibrin stabilization process, namely, factor XIII binding and the ability of alpha chains to undergo limited cross-linking to one another and to alpha 2PI.

Amino Acid Sequence↗
PubMed1994

[Functional characterization of a monoclonal antibody which interferes with the binding of t-PA to fibrin].

PURPOSE: Development of monoclonal antibodies capable of inhibiting the specific binding of t-PA to fibrin. MATERIAL AND METHODS: After immunization of Balb/c mice with recombinant t-PA (rt-PA) we selected the monoclonal antibody MA3B5 by its ability to inhibit the binding of t-PA to fibrin, and the MA2C1 devoid of this property. The influence of such antibodies was evaluated on fibrin plates, amidolytic assays and clot lysis assays. Furthermore, their interference with the activator bound to fibrin was assayed with a spectrophotometric solid phase assay (SOFIA). RESULTS: The results showed that MA3B5 totally inhibited the t-PA induced fibrinolytic activity on fibrin plates, reduced amidolytic activity by 86.5% and inhibited the clot lysis induced by t-PA in a dynamic system. In contrast, the MA2C1 showed no inhibition. By assessing the binding of t-PA to fibrin with the SOFIA assay we could demonstrate that only the MA3B5 reduced significantly (up to 90% with 100 micrograms/mL of antibody) the amount of t-PA bound to fibrin surface. CONCLUSION: We have purified and characterized a monoclonal antibody which specifically blocks the fibrin binding site of t-PA.

Animals↗
PubMed1994

[Pharmacodynamic study of mitomycin C mixed with fibrin glue for treatment of malignant brain tumors].

The chemotherapy for malignant brain tumors creates two major problems to be solved viz systemic toxicity and interference by the blood brain barrier. The interstitial chemotherapy with sustained release of anticancer drugs has been widely investigated to overcome these problems. The Mitomycin C (MMC) - contained fibrin glue might be a promising candidate for use in local chemotherapy of malignant brain tumors. We investigated pharmacokinetics of the MMC-contained fibrin clot in vitro, activity of the MMC for the cultured glioma cell line, and its effect on the normal mouse brain. The MMC concentration in saline was measured up to 96 hours after the placement of fibrin glue into 5, 10 and 15 ml of saline. Then we periodically replaced the saline to keep the concentration difference of the MMC between the saline and the fibrin clot and evaluated the dissolution of the MMC for 288 hours. The potency of the MMC to suppress the rat glioma cell line was measured after being dissolved from the MMC-contained fibrin clot. The effects of the MMC-contained fibrin clot were histologically evaluated. The MMC-contained fibrin glue, the MMC solution and the fibrin glue were separately injected into the mouse brains. Mice were sacrificed 24, 72, 168 and 336 hours after the injection and brains were examined with photomicroscopy. The MMC was released into the saline rapidly within 24 hours then gradually released until 96 hours had elapsed. Total amounts of the dissolved MMC were proportional to the amounts in the saline.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effect of fibrin sealant on the integrity of colonic anastomoses in rats with faecal peritonitis.

OBJECTIVE: To assess the influence of fibrin adhesive on the healing of colonic anastomoses in rats with and without faecal peritonitis. DESIGN: Controlled study. SETTING: Laboratory for experimental surgery, Erasmus University Rotterdam, The Netherlands. MATERIAL: 120 male Wag/Rij rats. INTERVENTIONS: All rats had a single layer end-to-end anastomosis fashioned with 7/0 polypropylene. Faecal peritonitis was then induced in half of the rats by placement of 200 mg powdered autoclaved rat faeces in the peritoneal cavity near the anastomosis. Rats were allocated to one of four groups (n = 30 in each): 1--control; 2--additional sealing with fibrin glue; 3--peritonitis alone; and 4--peritonitis with fibrin glue. MAIN OUTCOME MEASURES: Body weight, adhesion formation, anastomotic bursting pressure and collagen concentration around the anastomosis on days 2, 4, and 7 in 10 rats from each group. RESULTS: 11 rats died of peritonitis before the experiment was completed. Peritonitis caused increased formation of adhesions and abscesses, with or without fibrin sealant. Bursting pressure at the anastomosis was significantly reduced in peritonitis compared with controls on days 4 and 7, and this was not prevented by fibrin. Sealing of anastomoses resulted in lower bursting pressures on day 4 in control animals. Collagen concentration was significantly reduced in peritonitis with or without fibrin sealant on days 4 and 7, and after fibrin sealing of control anastomoses. CONCLUSION: Faecal peritonitis reduced mechanical strength and collagen concentration of colonic anastomoses, and this was not prevented by additional sealing of the anastomosis with fibrin sealant.

Anastomosis, Surgical↗
PubMed1993

Fibrin induction of thrombospondin in corneal endothelial cells in vitro.

PURPOSE: Fibrin deposition in the anterior chamber of the eye occurs in response to injury or inflammation and can permanently damage the corneal endothelium. Fibrin functions as a mediator of inflammation and wound healing by affecting cell morphology and function in a variety of cells, including corneal endothelial cells. We hypothesized that fibrin can directly induce corneal endothelial cells to express injury-related proteins (eg, thrombospondin [TSP]) necessary for corneal repair processes. METHODS: Bovine corneal endothelial cells (BCECs) were pulse- or continuously labeled with 35S-methionine in the presence or absence of in situ polymerized fibrin (2 mg/ml). BCECs were harvested after 3-48 hr, and 35S-labeled proteins were analyzed by SDS-PAGE, autoradiography, and immunochemical techniques. RESULTS: Fibrin selectively induced BCECs to express a high molecular weight (MW) protein that was present extracellularly in conditioned medium and fibrin matrix. This induction represented a 3-5 fold increase relative to nonfibrin-treated BCECs, was not accompanied by corresponding changes in 35S-labeled intracellular proteins, and was evident at early (3 hr) or late times (24 hr) post-fibrin treatment. The induced protein had an apparent MW of 180 kD (reduced) and > 420 kD (nonreduced), consistent with the characteristics of TSP. A polyclonal antibody to human TSP recognized the reduced form (180 kD) on Western blots and the native form (> 420 kD) in immunoprecipitation studies. CONCLUSIONS: Fibrin induces BCECs to express TSP, a matrix protein involved in cell-cell and cell-matrix interactions and implicated in wound healing.

Animals↗