MITOTIC EFFECTS OF IONIZING RADIATION EFFECTS ON THE MALIGNANT AND NONMALIGNANT EPIDERMAL HYPERPLASIA IN MICE. PART VI. EFFECTS OF SINGLE CONTACT IRRADIATION AFTER 60-DAY PRETREATMENT WITH CARCINOGENS OR TUMOR ENHANCER (in German)
The nature of mitotic response was analyzed in malignant (provoked by a carcinogen, 9,10-dimeihyl-1, 2-benzanthracene, DMBA) and in benign (provoked by a non-carcinogenic tumor enhancer, Tween 60) epidermal hyperplasia in female mice of the skin-tumor resistant RA strain after a single exposure of the mouse back to a /sup 90/Sr-/sup 90/Y contact source with a dose rate of about 1000 rad/9 min. The skin of the mouse back was pretreated with DMBA, and with Tween 60. respectively, for 60 days. During the pretreatment period, carcinomas developed in the DMBA group, whereas no tumors appeared in the mice pretreated with Tween 60. The dosages (60 gamma of DMBA, and 97 mg of Tween 60, respectively) proved well suited to the purpose of the experiment in that the effect of the carcinogen manifested itself in a more pure manner. The skin was irradiated on the 61st day. In each series and in each mouse, 500 mitotic figures (normal and pathologic) and the corresponding non-dividing nuciei were registered at postexposure hours 1, 6, 12, 24, 45, and 72. The total number of mitoses examined amounted to 80,000 and that of nondividing nuclei to 1,423,200. Conclusions were drawn only when differences were highly significant (P < 0.001). The response to irradiation in the 60-day experiment proved entirely different in malignant and in benign epidermal hyperplasia. As in the 10-day experiment, mice with malignant hyperplasia responded by development of severe mitotic disturbances and by disintegration of cells. Thus this condition was much more sensitive to irradiation than the benign state. It is pointed out that in planning a rational radiation therapy for tumors, attention must also be paid to the second growth facet, cell maturation and its disturbances, and not only to the first, cell proliferation, facet. (auth)
- Research Organization:
- Universitat, Helsinki
- NSA Number:
- NSA-18-019704
- OSTI ID:
- 4023243
- Journal Information:
- Strahlentherapie (West Germany), Journal Name: Strahlentherapie (West Germany) Vol. Vol: 123; ISSN STRAA
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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