Fibrinogen slide

After rinse and air drying, slide was covered over one horizontal area with anti-fibrinogen serum (f), over another with anti-7s gamma-globulin serum. Both were rinsed off 2 min later (see text). Note area of g on one is clearly visible, indicating the plasma had not fully converted its own globulin deposit... 

The change in biological response of the adsorbed fibrinogen molecule (conversion), is also noticeable with platelet adhesion studies. In confirmation of earlier studies of Zucker and Vroman (5), we found that, usually, less platelets adhered to areas of glass slides exposed to platelet-poor plasma for 3 min than areas exposed for 3 s. When, however, a gel-filtered platelet suspension was used in place of platelet-rich plasma, a dramatic difference in the number of platelets attached to the surface previously exposed to platelet-poor plasma for 3 s or 3 min occurred. Therefore, this more reproducible protocol was used to study not only the adhesion of platelets onto artificial surfaces but also as a probe of conversion. For this purpose we chose a series of block copolymers with controllable domain morphology (phase separation on a molecular scale) and different surface energies (wettability). Previous studies have shown that the degree of phase separation influences the interactions with blood components (6,7). 

Figure 1. Fibrinogen left between convex lens and glass slide by various dilutions of plasma (top row) and of fibrinogen solutions (bottom row)...

Figure 2. Fibrinogen left by intact plasma between convex lens and anodized tantalum-sputtered glass slide. Only right half of pattern was exposed to antiserum to fibrinogen (see text).

Figure 5. Fibrinogen (left) and kininogen (right) left by normal plasma between lens and glass slide (see text).

Among plasma proteins we studied at solution/air interfaces, fibrinogen behaved most remarkably. Compressed in a surface film balance (5), fibrinogen tended to form a cohesive film that could be lifted off the interface with a hydrophobic slide (6). The finding suggests that fibrinogen may form polymer-like complexes at certain interfaces even in absence of thrombin (7), the enzyme normally needed to polymerize fibrinogen into fibrin. 

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