Fibrinogen deposition

In some patients with IgA nephropathy (IgAN), intraglomerular coagulation plays a role in depositing fibrinogen (235,236). IgAN patients treated with urokinase show a marked improvement in urinary protein concentration, semm creatinine, and blood urea nitrogen levels (237). 

In the ellipsometer, plasma even when diluted about 150-fold, deposits immunologically identifiable fibrinogen but the film loses its ability to adsorb antibody to fibrinogen within minutes under these conditions. The loss is probably not caused by the plasma s proteolytic activity (18) and occurs more slowly at IOC than at 37C (19). At room temperature, undiluted plasma deposits fibrinogen within about 2 sec and the loss occurs within 30 sec. 

More recently, we found that the fibrinogen is replaced by high molecular weight kininogen (HMK) (20, 21). Studies with radi-olabelled fibrinogen rather than with antibodies to fibrinogen recently confirmed that plasma deposits fibrinogen and then removes it (22, 23). We found the event does not occur on various hydro-phobic surfaces others found it did (24). 

The most important reaction in blood clotting is the conversion, catalyzed by thrombin, of the soluble plasma protein fibrinogen (factor 1) into polymeric fibrin, which is deposited as a fibrous network in the primary thrombus. Thrombin (factor 11a) is a serine proteinase (see p. 176) that cleaves small peptides from fibrinogen. This exposes binding sites that spontaneously allow the fibrin molecules to aggregate into polymers. Subsequent covalent cross-linking of fibrin by a transglutaminase (factor Xlll) further stabilizes the thrombus. 

Shen M, Pan YV, Wagner MS, Hauch KD, Castner DG, Ratner BD, Horbett TA. Inhibition of monocyte adhesion and fibrinogen adsorption on glow discharge plasma deposited tetraethylene glycol dimethyl ether. Journal of Biomaterials Science, Polymer Edition 2001, 12, 961-978. 

The matter deposited by normal plasma onto globulin films that had (Table IV, Exp. No. 1) or had not been pre-exposed to protamine sulfate (not listed) did not adsorb matter out of anti-human fibrinogen serum and therefore was probably not fibrinogen. 

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