ABSTRACT
A fibrinogenolytic toxin of molecular weight 6.5 kDa has been purified from the venom of Indian monocled cobra (Naja kaouthia) by repeated cation exchange chromatography on CM-sephadex C-50. The purified toxin did not show any phospholipase activity but was mildly hemolytic on human erythrocytes. This toxin, called Lahirin, cleaved fibrinogen in a dose- and time-dependent manner. The digestion process apparently started with the Aα chain, and gradually other lower-molecular-weight chains were also cleaved to low-molecular-weight peptides. The fibrinolytic activity was completely lost after treatment with ethylene di-amine tetra acetic acid (EDTA). However, exposure to 100°C for 1 min or pre-treatment with phenyl methyl sulfonyl fluoride (PMSF) did not affect the fibrinolytic activity. Cleavage of di-sulphide bonds by β-mercaptoethanol or unfolding the protein with 4 M urea caused complete loss of activity of pure Lahirin.
ABSTRACT
In general, FDP and D-dimer values have a correlation in clinical conditions associated with disseminated intravascular coagulation(DIC) or coagulation activation. However, there are some patients with discordant results who demonstrate elevated FDP and negative D-dimer results by latex agglutination assays. The incidence and possible reasons for the discordance between FDP and D-dimer results were investigated through simultaneous measurements (n = 763) from clinical patients with suspected DIC or coagulation activation. 24.8% (189/763) of samples with elevated FDP were negative for D-dimer assays by the latex agglutination method. Further detailed analysis on randomly-selected discordant samples (n = 41) revealed that the most common reason for the discordance was the lower sensitivity of the semiquantitative latex agglutination method for D-dimer, compared with quantitative enzyme or other latex immunoassay. The other contributing factors to the discordance were accelerated fibrinogenolysis without secondary fibrinolysis, elevated soluble fibrin monomer and rheumatoid factor.