Various Properties during Clotting

The increase in opacity and the recoverable fibrin are plotted against time in Fig. 17, and the increase in opacity and the rigidity are plotted in Fig. 18, for systems in which the fibrinogen and thrombin concentrations, pH, and ionic strength are specified (Ferry and Morrison, 1947a)  

Recoverable fibrin (O) and opacity increase ( ), plotted against time, during clotting of solution with fibrinogen concentration 1 g./liter, thrombin 0.1 unit/cc., ionic strength 0.15, pH 6.3. Arrow denotes clotting time. FVom Ferry and Morrison (1947a). 

Since the relations between opacity and rigidity and the degree of partial conversion during clotting are not known, it is not possible at 

Beciprocal clotting time plotted against thrombin concentration, at ionic strength 0.30 and pH 6.64 to 6.81. Fibrinogen concentrations in g./ Uter 1, 3 2, 6 3,. 12 4, 24. From Ferry and Morrison (1947a). 

---

The second answer with respect to the earlier acquisition of risk data must come from the laboratory. Not from animal studies, which in this field are of very restricted value, but from biochemical and particularly hematological work. When during the 1990s various groups began to examine in detail the effects of the third-generation contraceptives on processes related to the clotting system, they identified a series of properties that could very well explain an increased incidence of thrombosis. 

To date in vivo blood flow measurements of various ions have only been carried out sporadically. This is due to the problems associated with this type of measurement. Since ion-selective electrodes can usually tolerate temperatures only as high as about 50°C or just slightly above 100°C, the necessary sterilization is not so simple. With the newer liquid ion-exchanger and ion-carrier electrodes, too little is known about the toxicity properties of the active phases. The blood-compatible glass membrane electrodes often collect albumin deposits on the electrode surface during flow measurements, which increase with time and cause the electrode potential to drift. Sometimes blood clots will also form, which are perilous to the research subject. 

---