The plasma protein FXII (Hageman factor) has been shown to be linked with the plasma defence systems of coagulation, fibrinolysis, kallikrein-kinin and complement. It can be activated by surface contact activation and in solution. Surface contact activation is a complex phenomenon involving negatively charged surfaces, FXII, high molecular weight kininogen and plasma kallikrein. Fluid-phase activation can be effected by a variety of serine proteases. In both types of activation the FXII zymogen is converted to active enzymes. FXII levels in plasma are low or undetectable in both inherited deficiencies and in a variety of clinical conditions. FXII levels can also be elevated in some clinical conditions. Although discovered as a clotting protein FXII appears to play an important role in the kallikrein-kinin and fibrinolytic systems and also has effects on cells. Recent studies suggest that therapeutic blockade of activation of FXII can be of benefit in certain clinical conditions.

Nowadays in many European heart centers the activation of the fibrinolytic system, always occurring during cardiopulmonary bypass, is routinely reduced by high-dose application of the proteinase inhibitor aprotinin (total of > 4 million KIU). In this study parameters of myocardial ischemic injury were investigated with the aim of identifying further benefits of aprotinin, particularly the protection of the myocardium during the ischemic period of aortic crossclamping. Forty patients with coronary artery disease who underwent aorta-coronary bypass grafting were randomly and in a double-blind fashion divided into two groups, one that received high-dose aprotinin therapy and one that received only saline solution. Markers such as troponin T, with high specificity for detection of myocardial ischemia and infarction, and markers with more general specificity such as creatine kinase, its isoenzyme, and lactate dehydrogenase showed significantly increased values after ischemia in both groups. In patients who received high-dose aprotinin therapy 3 days after cardiopulmonary bypass all parameters measured showed significantly lower levels compared with those in the control group. Therefore we can presume that the application of high-dose aprotinin provides myocardial protection from perioperative ischemic injury.

An einer unausgewählten Population von 2040 Probanden (1075 Männer, 965 Frauen) wurden die Volumenaktivitäten der Enzyme* GOT, GPT und AP entsprechend den Empfehlungen der Deutschen Gesellschaft für Klinische Chemie bestimmt. Engen Zusammenhang mit den Enzymaktivitäten zeigten die Größen y-GT, Glucose, relatives Körpergewicht und Alter. Durch Eliminierung von Probanden mit pathologischen Werten der signifikanten Einflußgrößen y-GT, Bilirubin, Cholesterin, Glucose und Hämoglobin wurde eine Referenzgruppe von 1376 Personen (708 Männer, 668 Frauen) gebildet. Die bei diesen Probanden erhobenen Enzymaktivitäten dienten zur Schätzung der 0,05-und 0,95-Quantile unter zusätzlicher Berücksichtigung von Lebensalter und Gewicht. Es ergaben sich für Normalgewichtige folgende Referenzwerte im Serum: GOT < 19 U/l (Männer)

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