11.   Little is known, however, about plasminogen activators in solid tumours of the upper gastrointestinal tract.

12.   The sandwich ELISA for urokinase type plasminogen activator was carried out according to Binnema et al.

13.   The amount of urokinase type plasminogen activator antigen in the samples was calculated from an eight point standard curve of urokinase type plasminogen activator.

14.   Absolute quantities of tissue type plasminogen activator antigen in the samples were calculated from an eight point standard curve of tissue type plasminogen activator.

15.   Urokinase type plasminogen activator and tissue type plasminogen activator activities were measured by a spectrophotometric enzyme assay as described previously.

16.   Activator activities were expressed as mIU urokinase type plasminogen activator or tissue type plasminogen activator per mg protein.

17.   The antigen and activity concentrations of both plasminogen activators in normal tissue showed a steady increase going from squamous oesophagus to the stomach and duodenum.

18.   Urokinase type plasminogen activator and tissue type plasminogen activator in squamous oesophagus were significantly lower than in the stomach.

19.   Also with respect to tissue type plasminogen activator, antigen and activity were in general significantly correlated in carcinomas and normal mucosa.

20.   Oesophageal tissue was found to contain significantly less urokinase type plasminogen activator and tissue type plasminogen activator, both in antigen and activity, compared with stomach tissue.