Hageman Factor, activation

The intrinsic and extrinsic pathways cross over at several points. Hageman factor, activated by the intrinsic pathway, can switch on proconvertin of the extrinsic pathway. Convertin can then feed back into the intrinsic pathway to help activated PTA activate Christmas factor. Thrombin itself can trigger both branches of the clotting cascade by activating antihemophilic factor, which is required to help activated Christmas factor in the conversion of Stuart factor to its active form, and also by activating proconvertin. ... 

In addition to activating blood clotting (9), activated Hageman factor activates prekallikrein of the kinin system, which leads to bradykinin that causes vascular vasodilation. Activation of Hageman factor and blood clotting also leads to the... 

Hageman factor — Active form Hageman factor ... 

Mandle RJ, Kaplan A Hageman factor substrates. Human plasma prekallikrein mechanism of activation by Hageman factor and participation in Hageman factor-dependent fibrinolysis. J Biol Chem 1977 252 6097-6104. 

Griffin JH Role of surface in surface-dependent SO activation of Hageman factor (blood coagulation factor XII). Proc Natl Acad Sci USA 1978 75 1998-2002. 

Schreiber A, Kaplan A, Austen K Inhibition by 62 ClINH of Hageman factor fragment activation of coagulation, fibrinolysis, and kinin generation. J Clin Invest 1973 52 1402-1409. 

Kaplan A Mechanisms of activation of the classical pathway of complement by Hageman factor frag- 91 ment. J Chn Invest 1983 71 1450-1456. 

Kaplan AP, Austen KF A prealbumin activator of prekallikrein. II. Derivation of activators of prekal-likrein from active Hageman factor by digestion with plasmin. J Exp Med 1971 133 696-712. 

H4. Hack, C. E., and Dors, D Activation and inhibition of factor XII (Hageman factor) in vivo. Curr. Opin. Invest. Drugs 1,95-110 (1992). 

Kl. Kalter, E. S., Daha, M. R Ten Cate, J. W Verhoef, J., and Bouma, B. N., Activation and inhibition of Hageman factor-dependent pathways and the complement system in uncomplicated bacteremia or bacterial shock. J. Infect. Dis. 151,1019-1027 (1985). 

XII Hageman factor Intrinsic Activated by surface contact or the kallikrenin system. Xlla helps initiate intrinsic system... 

Figure 17.1 Summary of the four cascades that result from trauma or bleeding and the reactions they catalyse. These are all activated by the blood clotting factor, Xlla (also known as the Hageman factor). Details of each cascade are presented in Figures 17.2, 17.4 and 17.6. Factor XII is activated by collagen and negatively charged surfaces to form the active form, Xlla.

Kallikreins are present in plasma and in several tissues, including the kidneys, pancreas, intestine, sweat glands, and salivary glands. Plasma prekallikrein can be activated to kallikrein by trypsin, Hageman factor, and possibly kallikrein itself. In general, the biochemical properties of tissue kallikreins are different from those of plasma kallikreins. Kallikreins can convert prorenin to active renin, but the physiologic significance of this action has not been established. 

One method of producing a biocompatible surface is to prevent adsorption of proteins. If proteins adsorb or otherwise become attached to a polymer surface, the attachment can interfere with the normal cell functions. The interaction of a polymer surface and blood is equally problematic. A component in blood known as the Hageman factor detects hydrophobic surfaces. The signaling involves attachment of the factor to the surface and by the process of attachment, the factor becomes activated. This is the first step in the inflammation response that can lead to rejection. Thus, the development of a hydrophilic surface with minimal protein adsorption may become a strategy for the development of compatible medical devices. 

Early observations showed that blood clotted faster in clean glass tubes than in siliconized glass. When Mr. Hageman s blood failed to clot in vitro, it was speculated that a Hageman Factor was responsible for the in vitro activation of blood coagulation (see Ref. 2) for a delightful account). 

In the mid to late 60 s, considerable interest in the pre-adsorption of proteins evolved. The basic idea was that if one could saturate the surface with a layer of proteins, then the surface would not be available for the binding and activation of Hageman Factor... 

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