Procedure for determination of oxidative modification of plasma fibrinogen

: The purpose of the present study was to develop a new procedure for determining the oxidative modification of plasma fibrinogen. The procedure was developed to use blood plasma from 96 males aged 35-60 years who had cardiovascular diseases: 49 patients with coronary heart disease (CHD), including 16 patients with sub-acute myocardial infarction (MI), and 47 patients with arterial hypertension without CHD. The new procedure is as follows: a rapid fibrin isolating method, a reaction with 2,4-dinitrophenylhydrazine in 2 M HCl solution, by subsequently rinsing in the ethanol : ethyl acetate (1:1) solution, dissolving the precipitate in 8 M urea, and by determining the level of the resultant dinitrophenylhydrazones by spectrophotometry at 363 nm, followed by conversion to the plasma concentration of fibrinogen. The procedure is of informative value for the degree of oxidative fibrinogen modification under oxidative stress; it is technically simple, takes little time, and shows a good reproducibility. The values of determined oxidized plasma fibrinogen by the developed procedure show a high positive correlation with the estimates of oxidized total blood protein fraction and with the values of blood lipid peroxidation. The detected elevated level of oxidized fibrinogen in CHD and MI suggests that this index is a new diagnostic marker of oxidative stress in cardiovascular diseases of atherosclerotic genesis.