[Determination of prekallikrein in the plasma of neonates].

The authors assessed plasma prekallikrein (PK) after its conversion into the active enzyme kallikrein from the rate of breakdown of the specific chromogenic substrate NO-Pro-Pre-Arg-pNA. Activation of PK was achieved by the parallel contact method, using dextran sulphate (DS) and by direct activation by the Hageman's factor fragment (HFf). Contact activation assumes the presence of Hageman's factor (HF) and high molecular kininogen (HMW-K) in plasma.