Food Lipids: Chemistry, Nutrition, and Biotechnology

Figure 16 Schematic representation of the fibrinolytic pathway. Fibrin is degraded by
plasmin. The conversion of plasmin from plasminogen is regulated by the action of tissue
plasminogen activator (t-PA). t-PA activity is suppressed by plasminogen activator inhibitor
type-1 (PAI-1), whereas plasmin is inhibited by � 2-antiplasmin.
time, and the fibrin plate assay. The dilute and euglobulin clot lysis time measure
total fibrinolytic capacity. The total blood sample or the insoluble protein sample
(euglobulin fraction) is diluted with a buffer, clotted, and the lysis time of the clot
recorded. In the fibrin plate assay, a standard volume of the euglobulin fraction of
plasma is added to standardized plasminogen-rich fibrin plates and the amount of
lysis is recorded. In more specific assays, total plasma concentrations of t-PA and
PAI-1 can be determined with enzyme-linked immunosorbent assays. Plasma t-PA
and PAI-1 activities can be estimated with a chromogenic assay.
2. Fibrinolysis and Coronary Heart Disease
From the NPHS has been reported that low fibrinolytic capacity of plasma, measured
as clot lysis time, was significantly associated with increased CHD risk in men aged
40–54 [89]. In addition, Hamsten et al. [90] have reported that higher concentrations
of PAI-1 were associated with increased risk of reoccurrence of coronary events.
3. Dietary Fats and Fibrinolysis
a. Total Fat Content of Diets. Marckmann et al. [76,77] found in both a short
term (2 week) and a longer term trial (8 months) that plasma euglobulin fibrinolytic
capacity and plasma t-PA activity were increased on low-fat/high fiber diets as compared
with high-fat/low-fiber diets (Fig. 17). No changes were observed in t-PA and
PAI-1 antigen concentrations. In agreement with these results, Mehrabian et al. [91]
reported decreased plasminogen and PAI-1 activities, after consumption of a low-fat/
high-fiber/low-cholesterol diet with less than 10% of energy from fat for 21 days.
This was associated with decreased t-PA antigen concentrations. However, from these
studies it is not possible to conclude whether the changes observed were due to the
lower fat or cholesterol contents, or the higher fiber content of the diets.
In another study, Marckmann et al. [78] have also compared two diets, which
differed in total fat content though fiber intake and the relative fatty acid composition
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