Abstract: For the detection of proteins containing phosphorylated tyrosine the sample of a body fluid is incubated with at least two receptors R.sub.1 and R.sub.2 whereby a change in signal is produced by binding of at least the receptors R.sub.1 and R.sub.2 with the substance to be detected in the sample solution and in which in each case one of the two receptors contains an antibody or its derivative capable of specifically binding to the protein to be detected and the other receptor contains an antibody or its derivative capable of specifically binding to phosphorylated tyrosine and the signal change caused by the binding is determined in the sample.

Abstract: The present invention concerns an improved method for the determination of fibrin in body fluids in which before the actual determination the sample solution containing fibrin is incubated in the presence of thiocyanate, iodide, magnesium or/and guanidinium ions.

Abstract: In order to detect a small cell lung carcinoma, synaptophysin, its oligomers and/or its fragments are determined in body fluids.

Abstract: In order to determine antithrombin III in body fluids by reacting the sample with thrombin and a chromogenic substrate which forms a colour by the action of thrombin and measurement of the colour formed, the reaction is carried out in the presence of denaturing agents or of the tetrapeptide Gly-Pro-Arg-Pro and an oligopeptide is used as the substrate which has a sensitivity to thrombin which is a factor of 5 to 100-fold lower compared With Tos-Gly-Pro-Arg-pNA

Abstract: In order to aid in the detection of malignant diseases the sample of a body fluid is incubated with at least two receptors R.sub.1 and R.sub.2 in which a signal change is produced by binding of at least the receptors R.sub.1 and R.sub.2 to the substance to be detected in the sample solution and in which one of the two receptors contains a monoclonal antibody which binds to the amino acid sequence 311 to 335 of cytokeratin 19 and the other receptor contains a monoclonal antibody which binds to the amino acid sequence 346 to 359 of cytokeratin 19 and the signal change in the sample caused by the binding is determined.

Abstract: The present invention provides a process for the photometric determination of protein C and/or protein S activity, especially in plasma, wherein the sample containing the protein C and/or protein S to be determined is incubated with a protein C activator from snake venom with the formation of activated protein C and/or protein S and the decrease of the formation of thrombin from prothrombin brought about by the coagulation factors and the activators thereof is determined by means of a chromogenic thrombin substrate.