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Insoluble "fibrin" in human aortic intima. Quantitative studies on the relationship between insoluble "fibrin", soluble fibrinogen and low density lipoprotein.

A quantitative assay for fibrin or other insoluble fibrin-like antigens ("fibrin") in small samples of intima is described. Tissue samples were subjected to electrophoresis directly from the intima into an antibody-containing gel to remove and measure fibrinogen and other soluble fibrin reactive antigens (FRA). The residual tissue was then exhaustively incubated with plasmin, and the soluble fragments generated from the insoluble "fibrin" were measured by quantitative immunoelectrophoresis. "Fibrin" accounted for about 2% of the tissue dry weight in normal intima and the ratio fibrinogen/"fibrin" was 1-1.5. In the gelatinous lesions, which seem to be the precursors of fibrous plaques, there was a small increase in "fibrin" but a substantial increase in fibrinogen and low density (LD)-lipoprotein, and the ratio fibrinogen/"fibrin" rose to about 3, which suggests that the increase in "fibrin" is secondary to increased permeation of fibrinogen. At the edges of large plaques there was also a threefold increase in fibrinogen, but "fibrin" increased fivefold, and accounted for 10% of the tissue dry weight. The same high concentration was found in the centres of large fibrous plaques with advanced atheroma lipid. Raised levels of "fibrin" were accompanied by raised levels of fibrinogen in most tissue samples. About 80% of the total soluble FRA could be clotted with thrombin; there was no significant difference between normal intima and lesions, and the proportion clotted was not related to "fibrin" content.

Aged

Precipitation of fibrin monomers and fibrin degradation products by ristocetin.

Ristocetin, at relatively low concentrations (1.0 mg/ml-1.5 mg/ml), can selectively precipitate fibrin monomers and fibrin degradation products (fdp) from plasma without effect on fibrinogen or fibrinogen degradation products (FDP). 125I-labeled fibrin monomers and fibrin degradation products were precipitated by ristocetin when their plasma concentrations were greater than 0.25 microgram/ml and 50 microgram/ml, respectively. In order to obtain a visible precipitated, 2 microgram/ml of fibrin monomers of 50 to 100 microgram/ml of fibrin degradation products were necessary. These effects were optimally observed under the following conditions: (1) temperature, 20 C to 37 C; (2) pH, 7.0 to 7.5; and (3) incubation time, 15 to 60 minutes. Late-fibrin degradation products are approximately eight times less sensitive to ristocetin-induced precipitation than early-fibrin degradation products. Plasma medium is essential for the differentiation of fibrin monomers and fibrin degradation products from fibrinogen and fibrinogen degradation products by ristocetin. These results suggest that the specific detection of fibrin monomers and fibrin degradation products in plasma may be easily performed by ristocetin.

Anticoagulants

Autologous Fibrin Glue in Pterygium Surgery as an Alternative to Commercial Fibrin Glue.

PURPOSE: The aim of this study was to evaluate the efficacy and safety of autologous fibrin glue in pterygium surgery, comparing it with commercial fibrin glue in terms of postoperative complications, graft stability, and recurrence rate. METHODS: A prospective, randomized, double-blind study was conducted, involving 42 patients with primary pterygium who underwent autologous conjunctival-limbal transplantation. The graft was fixed using autologous fibrin glue (Group 1, G1) or commercial fibrin glue (Group 2, G2). All patients underwent surgery performed by the same surgeon and were reevaluated on postoperative days 7, 30, 90, and 180 by an independent observer, assessing clinical parameters in the preoperative, intraoperative, and postoperative periods. RESULTS: No cases of severe adverse events were reported. Complete graft dehiscence occurred in 1 patient from G1. The G2 group had more cases of subconjunctival hemorrhage ( P = 0.0355). Pyogenic granuloma was observed in 1 patient from G2 and 2 patients from G1. There was no significant difference in recurrence rates between the groups (15% in G1 vs. 5% in G2; P = 0.2918). In both groups, graft dimensions tended to decrease slightly in the early postoperative period, followed by stabilization. CONCLUSIONS: Autologous fibrin glue demonstrated efficacy and safety comparable to commercial fibrin glue, making it a viable alternative to conjunctival graft fixation in primary pterygium surgery.

Humans

Detection of soluble intermediates of the fibrinogen-fibrin conversion using erythrocytes coated with fibrin monomers.

The presence of minimal amounts of fibrinogen-fibrin intermediates in human plasma was visualized by an agglutination reaction of glutaraldehyde-treated human erythrocytes coated with purified fibrin monomers. A degree of monomer coating was established which produced erythrocytes not agglutinated by normal plasma but by plasma containing minimal amounts of soluble complexes of fibrinogen with fibrin monomers. Under standardized conditions of coating, erythrocyte concentration, temperature, pH, and incubation time, the agglutination time varied with the ratio of soluble fibrin to fibrinogen in plasma. The test was sensitive down to a soluble fibrin concentration of 0.675% of the plasma fibrinogen concentration. Early fibrinogen and fibrin degradation products (FDP) in the plasma led to a prolongation of the agglutination time at a concentration of more than 16 mg/100 ml. Late FDP in a concentration of 100 mg/100 ml did not convert a positive test to negative. The test was not affected by heparin and protamine at concentrations of up to 12.5 and 50 NIH units/ml, respectively.

Batroxobin

Platelet and fibrin(ogen) deposition in the artificial kidney. The influence of haematocrit, fibrin monomer and platelet inhibitors. An in vitro study.

The effect of variations in haematocrit (hct) on the retention of 51Cr-labelled platelets and 125I-labelled fibrinogen from normal, heparinized, human blood, circulated in an experimental "mini-Kiil" dialyzing system, was studied. Platelet retention (PR) on dialysis membranes and blood lines was found to increase with increasing hct. When only platelet rich plasma was circulated, a significantly lower PR was noted on the blood lines. Fibrin(ogen) deposition on the same surfaces showed a similar tendency. When 125I-labelled fibrin monomer was added to normal blood, prior to dialysis, fibrin deposition on the membranes and blood lines was of a much higher degree than in the control. However, PR was not significantly influenced by the presence or deposition of the fibrin monomer. Reduced platelet function, caused by incubation with acetylsalicylic acid prior to dialysis, led to less PR on the blood lines, but not on the membranes. The observed difference was, however, not statistically significant (p = 0.06). Pretreatment of platelets with prostaglandin E1, however, was able to reduce PR significantly both on dialysis membranes and blood lines.

Aspirin

Fibrin membrane endowed with biological function. IV. Formation of cross-links between fibrinogen (or fibrin) and ribonuclease by transglutaminase.

Transglutaminase from guinea pig liver catalyzed the formation of cross-links between fibrinogen (or fibrin) and ribonuclease. Using transglutaminase, immoblized ribonuclease was prepared by two separate methods: (1) fibrinogen-ribonuclease conjugates formed by transglutaminase were treated with thrombin to make fibrin membrane bound covalently to the enzyme; (2) fibrin polymer formed from fibrinogen with thrombin was covalently bound to ribonuclease by transglutaminase to make fibrin-ribonuclease conjugates.

Animals

Ristocetin precipitation test: a new simple test for detection of fibrin monomer and fibrin degradation products.

The ristocetin precipitation test was designed as a simplified test to detect fibrin monomers and fibrinogen/fibrin degradation products (FPD/fdp). The ristocetin precipitation test is positive in plasma samples containing either fibrin monomer (greater than 5--10 microgram/ml) or early fdp (greater than 50--100 microgram/ml). The ristocetin precipitation test is negative in plasma with fibrinogen concentrations to 1,000 mg/dl or fibrinogen degradation products FDP) and late fdp to 400 microgram/ml. The ristocetin precipitation test is positive in plasmas collected from rabbits after the infusion of thrombin (2.7 u/kg) or thrombin and streptokinase (10,000 u/kg); the test is negative in plasmas from animals treated with streptokinase or saline solution alone. The ristocetin precipitation test is negative in normal human plasmas and plasmas from patients who have primary firbinogenolysis, but positive in plasmas from patients with disseminated intravascular coagulation. These results suggest that the restocetin precipitation test can be a useful test for the detection of plasma fibrin monomers and early fdp.

Animals

Identification of fibrin oligomers in sonicated fibrin clots.

Clots of bovine fibrin, with both coarse and fine structure, and ligated to different extents by fibrinoligase, have been broken up by ultrasonic agitation and the sonicates have been examined by ultracentrifugal sedimentation. Sonication is followed by gross aggregation of the fragments unless guanidine hydrochloride is introduced (order of 1 M). In that case, sonicates of gamma-ligated fine clots contain two species whose sedimentation coefficients correspond to fibrin monomer and an oligomer with twice the monomer cross-section area and at least 20 monomer units, presumably with the structure of lateral dimerization with staggered overlapping. If the gamma ligation is incomplete, shorter oligomers are identified. The monomer and oligomer with degree of polymerization greater than 20 appear also in sonicates of coarse clots, but in smaller amounts, the principal product consisting of larger aggregates. The implications of these results with respect to metastability of the fine clot and the pattern of polymerization are discussed.

Animals

Soluble fibrin complexes in early fibrin digests.

Early fibrin digests were analyzed in the ultracentrifuge and were found to contain compounds with molecular weights up to 3 X 10(6); these compounds are considered to be soluble fibrin complexes. Their similarity with intermediate polymers in inhibited clotting systems has been stressed. Their viscosity at low shear rates is extremely high; therefore, a rapid method to establish their presence in plasma would be the measurement of plasma and serum viscosity at low shear rates, moreover, they shorten the clotting time (thrombin time) of fibrinogen considerably.

Animals