CONVEX-LENS-ON-SLIDE - A SIMPLE SYSTEM FOR THE STUDY OF HUMAN-PLASMA AND BLOOD IN NARROW SPACES

On clot-promoting surfaces, intact normal blood or plasma deposits fibrinogen and then supplants it with high MW kininogen (HMWK). On glass, plasma layers of < .apprx. 25 .mu.m thick, while still containing enough fibrinogen to coat the surrounding surfaces, lack sufficient HMWK/surface area to remove this fibrinogen deposit. Normal intact citrated plasma allowed to enter the space between a glass slide and a convex lens resting belly-down on the slide will leave a disc of fibrinogen where the thickness of plasma layer was below this critical height H. The discs of fibrinogen left by plasma that lacks HMWK pathologically or by activation or dilution, are larger, the required H being greater. Plasma dilution (final volume divided by original plasma volume) plotted against H yields a straight line. In preliminary series, the slope of this line increases with the atomic weight of 5 metals whose oxidized surfaces were used as substrates. In whole blood collected in either heparin or ACD, a circle of platelets adheres to oxidized silicon, anodized Ta, or glass; this circle is similar in size to the one of fibrinogen left by plasma.