6 research outputs found
Recommended from our members
Late biological effects of ionizing radiation as influenced by dose, dose rate, age at exposure, and genetic sensitivity to neoplastic transformation. [Gamma radiation, mice]
A most comprehensive investigation is in progress at the Los Alamos Scientific Laboratory to study the late biological effects of whole-body exposure to gamma irradiation as they may be influenced by total dose, dose rate, age at exposure, and genetic background. Strain C57B1/6J mice of four age groups (newborn, 2, 6, and 15 months) were given five doses (20, 60, 180, 540, and 1620 rad) of gamma rays, with each dose being delivered at six dose rates (0.7, 2.1, 6.3, 18.9, 56.7 rad/day and 25 rad/min). Forty to sixty mice were used in each of the approximately 110 dose/dose-rate and age combinations. The study was done in two replications with an equal number of mice per replication. Strain RF/J mice were used in a companion study to investigate the influence of genetic background on the type and magnitude of effect. Results of the first and second replications of the 15-month-old age group and data on the influence of genetic background on biological response have been completed, and the results show no significant life shortening within the dose and dose-rate range used
Recommended from our members
Delayed radiation injury of gut-exposed and gut-shielded mice. II. The decrement in life span
Two mouse strains (RF/J and C57B1/6J) were exposed to x-ray doses totaling 400, 800, and 1200 rad. Total doses were given in 200-rad fractions at 7-day intervals to the whole body, gut only, or bone tissue with the gut shielded. Animals were anesthetized during exposure. Two control groups were used. A sham control group was anesthetized but not exposed to x rays, and another control group received neither anesthesia nor x-radiation. All mice were retained in a standard laboratory environment for observations on life span and histopathology at death. Life shortening was observed in all irradiated groups of strain RF/J mice and was attributed primarily to an increase in incidence and/or earlier onset of neoplasia. Life shortening was observed in the C57B1/6J whole-body exposed mice, but the effect appeared to be noncarcinogenic. Shielding of the bone or gut tissue proved to have a 100% sparing effect in strain C57 mice and none in strain RF mice. In both mouse strains, the sham control groups (anesthetized but not irradiated) showed approximately 8% life shortening below the non-anesthetized control groups and increased incidences of neoplasia of approximately 40%, suggesting that sodium pentabarbital may be as carcinogenic as x-radiation
Recommended from our members