Subjects studied are as follows:
late effects of an in utero irradiation on the central nervous system;
early and late radiation damage to the hemopoietic and immune system of newborn animals;
effect of fractionation of gamma-rays and neutrons on cancer induction and promotion in mouse liver;
the effect of age on tumour induction by radiation alone or combined with a chemical carcinogen.
Little attention has been devoted up to now to the hazard of very low doses of irradiation (<20 cGy) on the development of the central nervous system. However, in close relationship with the present exponential development in microelectronics, and in quantitative image analysis, numerous developmental abnormalities can now be detected at much lower dose levels than foreseeable just a few years ago. It is also our conviction that the relatively important anatomical alterations which were found by such methods must be the consequences of numerous transient and/or chronic changes occurring at the deeper ultrastructural, macromolecular and molecular levels.
The present studies will provide invaluable clues leading towards the discovery, in the near future, of more subtle abnormalities present even after lower doses of irradiation (<1 cGy) and eventually close enough to the exposure range found in everyday life.
THE PROPOSAL CONSISTS OF 4 PROJECTS. TWO OF THEM DEAL WITH TISSUES ESPECIALLY SENSITIVE TO AN IN UTERO OR NEONATAL IRRADIATION, THE CENTRAL NERVOUS SYSTEM, THE HEMOPOIETIC AND THE IMMUNOLOGICAL SYSTEM. THE OTHERS CONCERN THE MECHANISMS BY WHICH DIFFERENT RADIATION REGIMENS (FRACTIONATION AND QUALITY) INDUCE AND/OR PROMOTE CANCER,AND HOW THIS IS MODIFIED BY AGE AND CHEMICAL AGENTS.
1. LATE EFFECTS OF AN IN UTERO IRRADIATION ON THE CENTRAL NERVOUS SYSTEM.
2. EARLY AND LATE RADIATION DAMAGE TO THE HEMOPOIETIC AND IMMUNE SYSTEM OF NEW-BORN ANIMALS.
3. EFFECT OF FRACTIONATION OF GAMMA RAYS AND NEUTRONS ON CANCER INDUCTION AND PROMOTION IN MOUSE LIVER.
4. THE EFFECT OF AGE ON TUMOUR INDUCTION BY RADIATION ALONE OR COMBINED WITH A CHEMICAL CARCINOGEN.