Late Effects of Fast Neutrons and Gamma-Rays in Mice as Influenced by the Dose Rate of Irradiation: Induction of Neoplasia

The dose-response for x-ray induction of myeloid leukaemia in male CBA/H mice

“…The replicates completed so far with 6 doses in the range 0.75-6.0Gy together with the data on 0.25 and 0.5Gy at 0.5-0.55Gymin-1 (Table I) of interpretation when the frequency of neoplasms other than that under investigation is also affected tightforward in a dose-dependent manner, especially if the timing known cell of their occurrence is earlier than or coincident D2 and is with the neoplasm under investigation. Thus in Dquations (i) work on induction of chronic myeloid leukaemia in attempt is male X-rayed RF/Un mice (Upton et al, 1970) For equal there was a progressive reduction with increase in (as given by dose in "other leukaemias" from the control value the inferred of 32% to 15% after 4.5Gy and an increase in uation (v) is frequency of thymic lymphoma from 4-16% (with latent periods shorter than for chronic myeloid which was leukaemia). Control male CBA/H mice have 2-3% -& Davids non-myeloid "leukaemia" (mostly occurring late in life) and this is increased after 4.5 and 6.0 Gy Xas the only rays.…”

ras activation in human tumors and in animal model systems.

“…Both neutron and gamma irradiation are potential carcinogens, as demonstrated by the fact that both can transform cells in vitro (14)(15)(16) and induce tumors, including thymic lymphomas, in animals (17,18). One goal of this study was to determine whether the differences in qualities of these different forms of radiation might result in tumors with a different pattern of ras gene mutations.…”

Neutron radiation can activate K-ras via a point mutation in codon 146 and induces a different spectrum of ras mutations than does gamma radiation.

“…Neutron irradiation has been shown to transform cells in vitro (15,19) and produce tumors, including thymic lympho-* Corresponding author. mas, in animals (23,24). As yet, however, activation of specific oncogenes in neutron-induced tumors or cell transformants has not been described.…”

“…We have been studying ras oncogene activation in murine thymic lymphomas induced either by the chemical carcinogen N-nitroso-N-methylurea or by gamma radiation and have found activated K-and N-ras genes in a significant proportion of the tumors (7,20). In this study, we wanted to determine the extent of ras oncogene activation in neutroninduced thymic lymphomas in RF/J mice and compare it with our previous analysis of gamma ray-induced thymic lymphomas in the same strain of mouse.Gamma and neutron radiation are two types of ionizing radiation that deliver energy to target molecules in very different ways (13 (23,24). As yet, however, activation of specific oncogenes in neutron-induced tumors or cell transformants has not been described.…”

“…Gamma and neutron radiation are two types of ionizing radiation that deliver energy to target molecules in very different ways (13 (23,24). As yet, however, activation of specific oncogenes in neutron-induced tumors or cell transformants has not been described.…”