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G C Fischer

Publications and source records attributed to G C Fischer.

6 recordsLinked to original sources
PubMed1984

The effect of high molecular weight kininogen on surface-adsorbed fibrinogen.

High molecular weight kininogen (HMWK) plays an important role in altering the association of plasma fibrinogen with surfaces. Plasma initially deposits fibrinogen onto most materials, but on hydrophilic surfaces within 10 min adsorbed plasma fibrinogen cannot be detected on the surface by anti-fibrinogen antisera. However, using HMWK-deficient plasma, fibrinogen remains immunologically identifiable. The interrelationship of adsorbed plasma fibrinogen with kininogen on hydrophilic surfaces is studied further using glass slides stained for protein with Coomassie Blue, and oxidized silicon crystal slices in an automated ellipsometer. On glass slides when plasma that is deficient in both low molecular weight kininogen (LMWK) and HMWK, is reconstituted with HMWK (0.04 Units/ml), fibrinogen is no longer detected on the surface. This finding is specific for HMWK, since, when the same plasma is reconstituted with LMWK (220 micrograms/ml), the amount of fibrinogen detected on the surface is unchanged. The alteration of surface-adsorbed fibrinogen by HMWK is not due to plasmin-induced fibrinolysis, since it occurs in plasminogen-free plasma. In the ellipsometer, surface adsorption of normal plasma is associated with a significantly less (p less than 0.0005) thick protein layer (1.99 +/- 0.08 degree change in azimuth) than plasmas deficient in HMWK (2.32 +/- 0.11). Using ellipsometry, HMWK in plasma is shown to shorten the time in which immunologically detectable surface-adsorbed fibrinogen was removed or altered. These studies in a whole plasma system present further evidence that HMWK specifically modifies the association of plasma fibrinogen with hydrophilic surfaces.

Adsorption↗
PubMed1980

Interaction of high molecular weight kininogen, factor XII, and fibrinogen in plasma at interfaces.

Using ellipsometry, anodized tantalum interference color, and Coomassie blue staining in conjunction with immunologic identification of proteins adsorbed at interfaces, we have previously found that fibrinogen is the main constituent deposited by plasma onto many man-made surfaces. However, the fibrinogen deposited from normal plasma onto glass and similar wettable materials is rapidly modified during contact activation until it can no longer be identified antigenically. In earlier publications, we have called this modification of the fibrinogen layer "conversion," to indicate a process of unknown nature. Conversion of adsorbed fibrinogen by the plasma was not accompanied by marked change in film thickness, so that we presumed that this fibrinogen was not covered but replaced by other protein. Conversion is now showen to be markedly delayed in plasma lacking high molecular weight kininogen, slightly delayed in plasma lacking factor XII, and normal in plasma that lack factor XI or prekallikrein. We conclude that intact plasma will quickly replace the fibrinogen it has deposited on glass-like surfaces by high molecular weight kininogen and, to a smaller extent, by factor XII. Platelets adhere preferentially to fibrinogen-coated surfaces; human platelets adhere to hydrophobic nonactivating surfaces, since on these, adsorbed firbinogen is not exchanged by the plasma. The adsorbed fibrinogen will be replaced on glass-like surfaces during surface activation of clotting, and platelets failing to find fibrinogen will not adhere.

Adsorption↗
PubMedDate not supplied

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 molecular weight kininogen (HMWK). On glass, plasma layers of less than about 25 micron thick, while still containing enough fibrinogen to coat the surrounding surfaces, lack sufficient HMWK per surface area to remove this fibrinogen deposit. Thus 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. The present study shows that 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 five 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 tantalum, or glass; this circle is similar in size to the one of fibrinogen left by plasma.

Blood Cells↗