Differentiation between fibrin degradation products and fibrinogen degradation products by using newly developed ELISAs

We should distinguish fibrin degradation products (FbDP) from fibrinogen degradation products (FgDP) in order to analyze fibrinolysis in vivo. We analyzed some disorders associated with hyperfibrinolytic states using ELISA for FbDP, FgDP and total fibrin (ogen) degradation products (TDP) (ORGANON TEKNIKA). Each ELISA was useful in terms of reproducibility and dilution linearity of plasma samples. There was no cross-reaction between FbDP and FgDP. The FgDP/FbDP ratio in normal individuals was 1.65. In patients with DIC, it was 0.43, with FgDP level being increased. These results suggest that fibrinolysis is enhanced in patients with DIC, but it is accompanied by fibrinogenolysis. On the other hand, the FgDP/FbDP ratio in patients given urokinase (UK) was 2.88. This suggests that fibrinogenolysis is enhanced in them. In our study, the FgDP/FbDP ratio increased as DIC improved. Thus, we can regard this as an index of therapeutic effects in patients with DIC. We conclude that these three ELISA are useful in analyzing disorders associated with hyperfibrinolytic states.     

Rapid detection of cross-linked fibrin degradation products in plasma using monoclonal antibody-coated latex particles

Conformational and structural changes on conversion of fibrinogen to fibrin and its cross-linking by Factor XIIIa lead to the development of new antigenic determinants that permit differentiation between their plasminolytic cleavage products. A monoclonal antibody (DD-3B6/22) that is specific for cross-linked fibrin derivatives containing the D dimer configuration has been used in developing a latex agglutination procedure that can detect fibrin degradation products in either plasma or serum. Fibrinogen or its degradation products do not cross-react with this antibody. Results were calibrated with an enzyme immunoassay, which used a purified D dimer standard. Plasmas from 40 normal subjects, all having D dimer levels below 250 ng/mL measured by enzyme immunoassay, were all negative by latex assay. In contrast, positive latex agglutination titers were obtained with 87 of 88 patients with demonstrated deep venous thrombosis, pulmonary embolism, or disseminated intravascular coagulation. Compared to enzyme immunoassay, latex agglutination assay is less sensitive, but this latex procedure provides a rapid and less elaborate test for elevated levels of cross-linked fibrin degradation products in patients with thrombosis. Plasma assays for fibrin degradation products are preferable to those using serum.     

Pharmacokinetics of degradation products of fibrin and fibrinogen during alteplase therapy of acute myocardial infarction

Pharmacokinetics of fibrin degradation products (FbDP), D-dimers, fibrinogen degradation products (FgDP) and total degradation products (TDP) in plasma were investigated using ELISA methods in 12 patients undergoing therapy with alteplase (100 mg/3 h) for acute myocardial infarction. Peak concentrations of all degradation products occurred significantly later (1.6–2.5 h) than peak alteplase levels (2 min). Peak D-dimer concentrations (mean 2.6 μg/ml) were significantly lower than those of FbDP (7.1 μg/ml) or FgDP (7.8 μg/ml). However, the half-life of D-dimers (mean 13.3 h) was more than 4.5-fold longer than that of FbDP (2.9 h) or FgDP (2.8 h) (p<0.001). Consequently, areas under the plasma concentration-time curve (AUC) of D-dimers were comparable with those of FbDP or FgDP The ratios AUC(FbDP)/AUC(FgDP) and AUC(D-dimers)/AUC(FgDP) are proposed as new indices of fibrin specificity. Their values in this study (geometric mean, 95% CI) were 1.15 (0.60–2.20) and 1.30 (0.52–3.24) respectively. It is concluded that cross-linking may prolong the half-life of fibrin degradation products, and that complete time profiles of fibrin- and fibrinogen degradation products in plasma, rather than single point measurements, are essential for reliable quantification of fibrin specificity.     

Evaluation of two new assays for determination of serum fibrinogen/fibrin degradation products

Two new commercial assays for the detection of degradation products of fibrinogen/fibrin (FDP) were evaluated against two standard procedures. The first, a new hemagglutination inhibition (HAI) assay using glutaraldehyde-treated cells, was compared with the tanned red cell hemagglutination inhibition immunoassay (TRCHII). Analysis of 43 samples from patients with a variety of bleeding disorders and thrombotic conditions showed a high degree of correlation between methods (r = 0.934). The second new assay, a rapid slide test using antibody-coated latex particles, was compared with results obtained by electroimmunoassay. There were no significant differences in the results as assessed by two statistical parameters. It was concluded that both new tests are useful for routine use in clinical laboratories.     

纤维蛋白原对人血管平滑肌细胞株增殖和移行的影响

目的:探讨纤维蛋白原(Fg)、纤维蛋白(Fb)及其降解产物(FDPs)对体外人血管平滑肌细胞(VSMC)增殖与移行的影响。方法:采用细胞计数法和四唑盐(MTT)比色法测定VSMC增殖,通过刮伤实验(woundingmodel)和Transwell嵌套装置观察VSMC的移行。结果:Fg本身对VSMC增殖无促进作用,但可促进VSMC的移行,且呈浓度依赖关系;Fb及FDPs均可明显促进VSMC增殖和移行,Fb的作用还呈现浓度依赖关系,而FDPs作用呈现先增强后减弱的趋势,即在一定浓度范围内作用明显,高于或低于此范围作用较弱。结论:Fb及FDPs通过促VSMC的增殖和移行作用,可能在再狭窄和动脉粥样硬化中起重要作用。     

Fibrinogen and fibrinogen/fibrin degradation products in the urine of rabbits infected with Trypanosoma (Trypanozoon) brucei

Summary Studies have been carried out on the urine of rabbits infected with Trypanosoma (Trypanozoon) brucei to determine whether fibrinogen or fibrinogen/fibrin degradation products (FDP) could be detected. No fibrinogen was found but during the last two weeks of this 7-week infection low levels of FDP were present in the urine which did not exceed 5 g/ml. Rabbit urine was shown to contain a potent proteolytic enzyme capable of breaking down rabbit fibrinogen and both early and late FDP were present in the cleavage products. No deposits of fibrin were detected in the kidney, but casts were present in the urine suggesting renal damage. The most likely explanation of the urinary FDP is that either an increase in the glomerular permeability occurs allowing filtration of plasma FDP or a local fibrinogenolysis in the kidney tubules.     

Serum fibrin/fibrinogen degradation products as a prognostic index in acute myocardial infarction.

A study of the prognostic value of serum fibrin/fibrinogen degradation products (FDP) in 137 consecutive patients with acute myocardial infarction showed a positive correlation between high FDP levels and poor prognosis. Both the frequency of complications and the mortality were related to increased levels of FDP, the highest of which were found between the fourth and eighth days after infarction.     

The detection of fibrinogen/fibrin degradation products by means of a new antibody-coated latex particle

A rapid slide test for the detection of degradation products of fibrinogen/fibrin (FDP) using a new antibody-coated latex particle is described. The latex particle has been specifically coated with antibody to fragments D and E. The latex agglutination test (Thrombo-Wellcotest) has been compared with the tanned red cell haemagglutination inhibition immunoassay (TRCHII) in 143 patients with a variety of clinical conditions. There is a high degree of agreement between the methods with a coefficient of correlation of 0.83. The method provides a rapid, simple screening test for fibrin degradation products.     

Fibrinogen, fibrin and fibrin degradation products in relation to atherosclerosis

Many human atherosclerotic lesions, showing no evidence of fissure or ulceration, contain a large amount of fibrin which may be in the form of mural thrombus on the intact surface of the plaque, in layers within the fibrous cap, in the lipid-rich centre, or diffusely distributed throughout the plaque. Small mural thrombi are invaded by SMCs and collagen is deposited in patterns closely resembling the early proliferative gelatinous lesions. In experimental animals, thrombi are converted into lesions with all the characteristics of fibrous plaques, and in saphenous-vein bypass grafts, fibrin deposition is the main cause of wall thickening and occlusion. There seems little doubt that fibrin deposition can both initiate atherogenesis and contribute to the growth of plaques. Epidemiological studies indicate that increased levels of fibrinogen and clotting activity are associated with accelerated atherosclerosis, and although blood fibrinolytic activity has given inconsistent results, in arterial intima both fibrinolytic activity and plasminogen concentration are decreased in cardiovascular disease. Fibrin may stimulate cell proliferation by providing a scaffold along which cells migrate, and by binding fibronectin, which stimulates cell migration and adhesion. Fibrin degradation products, which are present in the intima, may stimulate mitogenesis and collagen synthesis, attract leukocytes, and alter endothelial permeability and vascular tone. In the advanced plaque fibrin may be involved in the tight binding of LDL and accumulation of lipid. Thus there is extensive evidence that enhanced blood coagulation is a risk factor not only for thrombotic occlusion, but also for atherogenesis. Enhanced blood coagulation frequently coexists with hyperlipidaemia and, together, these may have a synergistic effect on atherogenesis.     

Effect of fibrinogen degradation products on platelet aggregation

The digestion of fibrinogen with various concentrations of trypsin results in the formation of a variety of degradation products. Degradation products formed in this way have been purified by DEAE cellulose column chromatography and their effects on platelet aggregation investigated.TWO METHODS HAVE BEEN USED TO STUDY PLATELET AGGREGATION: a turbidimetric method which assesses platelet aggregation by the ability of adenosine diphosphate (ADP) to clump platelets and a method which assesses platelet adhesiveness by their ability to adhere to glass and to each other (modified Hellem technique, 1960).Three breakdown products produced by trypsin-digested fibrinogen were studied and all showed ;antithrombin' activity: two inhibited platelet aggregation, but one accelerated aggregation in both systems. Another product prepared by digestion of fibrinogen with urokinase-activated plasminogen has been shown to possess the ability to enhance ADP-induced platelet aggregation.