Biomedical subjects
Publications and source records attributed to H Fellner-Feldegg.
Dual laser operation of flow cytometers, using a single focussing lens for both beams, requires compensating for chromatic aberration of the lens. By using a prefocussing lens at a fixed position in one of the laser beams, complete focal length compensation is obtained without any loss in system performance.
Methods based on flow cytometry and sorting, autoradiography, and cloning were used to evaluate the potential for the enumeration of 6-thioguanine-resistant human peripheral blood lymphocytes assumed to be deficient with respect to the enzyme hypoxanthine-guanine-phosphoribosyl-transferase. Flow cytometric sorting of proliferating cells in the late S- and the G2-stages by means of DNA content, as measured by propidium iodide fluorescence, enabled an enrichment of variant cells to about 99%. The main source of false events was contaminating doublets of G0/G1 cells appearing in the sorting region. Doublet discrimination measured as the difference between pulse height and area (Ortho-50) accomplished no further improvement. A combination of propidium iodide fluorescence and bromodeoxyuridine incorporation, measured by fluorescent anti-bromodeoxyuridine-DNA antibodies, allowed flow cytometric enrichment to about 99.99% of variant cells. By sorting of 3H-thymidine-labeled cell nuclei from the late S- and the G2-phases and subsequent autoradiographic evaluation, partly resistant variants could be discriminated; variant frequencies of the same magnitude as for the cell cloning methods were obtained.
The modifying effect of zearalenone (ZEN) and diethylstilboestrol (DES) on ochratoxin A (OCT A) teratogenesis was investigated in the mouse. The three compounds, either individually or in combination (OCT A + ZEN or OCT A + DES), were administered orally on day 9 of pregnancy and the offspring were examined on day 19. All of the foetuses surviving exposure to ZEN (5-20 mg/kg body weight) or DES (0.125 mg/kg) were morphologically normal, while a high percentage (31-40%) of those exposed to OCT A (1-2 mg/kg) exhibited gross abnormalities such as exencephaly, open eyelids and microphthalmia. These effects were either not seen or occurred in a relatively small percentage when the toxin was combined with ZEN or DES. The results indicate that these non-steroidal oestrogenic substances of mycological (ZEN) and synthetic (DES) origin may protect the foetus from the teratogenic effects of OCT A by some unknown mechanism.
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