[Optimization of the polymerase chain reaction (PCR) for detection and characterization of shigatoxin producing Escherichia coli (STEC) in food]. / Optimierung der Polymerasekettenreaktion (PCR) zum Nachweis und zur Charakterisierung von Shigatoxin produzierenden Escherichia coli (STEC) in Lebensmitteln.

The polymerase chain reaction (PCR) was improved to detect shigatoxin producing Escherichia coli (STEC) in milk. Numbers of colony forming units (cfu) in test samples, concentrations and types of primers, amount of MgCl2, types of thermostable DNA-Polymerase, and cycling programs were modified up to obtain the cleanest electrophoretic pattern and the highest sensitivity. Experimental conditions for further characterization of STEC-isolates by means of PCR are given by summarizing data from literature.

[The validation of an enzyme immunoassay for the detection of antibodies to bovine leukosis virus]. / Die Validierung eines Enzymimmunoassays zum Nachweis von Antikörpern gegen das Rinderleukosevirus.

Validation of an enzyme immuno-assay for detection of antibodies against bovine leucosis virus is described in this paper. Internal standardisation of the test was done by means of a negative control serum. With absolute extinction of the negative control serum between 100 and 200 mE, a serum sample is rated positive, if its extinction is 1.5 times above the control. The methodological sensitivity of the enzyme immuno-assay described has proved to be four times as high as that of the immunodiffusion test. The results recorded at five diagnostic laboratories suggested a sensitivity of the test of 97.6 percent (92.1 to 100 percent) and a specificity of 98.1 percent (94.4 to 100 percent). The high efficiency of the test can be confirmed by immunoblotting.

[Detection of stimulator-induced cytotoxicity of human mononuclear cells in short-term culture]. / Untersuchungen zum Nachweis der stimulatorinduzierten Zytotoxizität von mononuklearen Zellen des Menschen in der Kurzzeitkultur.

A new test modification for the detection of stimulant-induced cytotoxicity of human mononuclear blood cells is described. Papain-treated human erythrocytes were used as indicator cells. The effector cells were lymphocytes. The ratio of target cells to effector cells was 10/1. Haemoglobin as a marker of lysis of the erythrocytes, released in the supernatant, was measured quantitatively in form of its pseudoperoxidase-activity. PHA, ConA and tannic acid were ascertained and tested as stimulants of cytotoxicity. The reaction was inhibitable by anti-human-lymphocyte-globulin. The test conditions were optimized in regard to incubation time, -temperature, -vessels, culture medium and target cells. The technique is easy to manipulate, has only slight pretensions to the equipment of the laboratory and appears to be very effective. We recommend to apply this method of stimulant-induced cytotoxicity within the detection of the immune state, especially in the progress of immunopathological diseases and the analysis of efficiency of immunosuppressive therapy.