COLONY-FORMING UNIT REPOPULATION AND SPLIT-DOSE RADIOSENSITIVITY IN ENDOTOXIN TREATED AND CONTROL LAF1 MICE
Abstract
Radiosensitivity of an animal, in terms of survival or death following midlethal exposure, is thought to be related to the surviving number of hematopoietic stem cells. After a sublethal exposure to radiation an animal's sensitivity to a subsequent exposure (LD50) might also be expected to be related to the number of stem cells which are present at any given time. In the present experiments with mice, the relationship was studied between split-dose LD50 and changes in the numbers of nucleated cells in the femur and the femoral content of colony-forming units (CFU's). These CFU's are proliferative cells in the marrow which when transplanted have the capacity to form nodules in the spleens of supralethally irradiated recipient mice. Many stem cell-like attributes have been conferred to CFU's and the CFU is frequently referred to as a hematopoietic stem cell. Changes in marrow cellularity and CFU content were studied for three weeks after exposure to 450 R, and preliminary LD50's were determined at 5 or 14 days. One group of animals was given bacterial endotoxin before the 450 R exposure. During the first week after 450 R, the endotoxin-treated animals showed an accelerated recovery in terms of numbers of nucleated marrow cells and CFU's, and at day 5 the femoral CFU content of the endotoxin-treated animals was ten times as great as that of the controls.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 23, 1966
- Accession Number
- AD0635600
Entities
People
- E. John Ainsworth
- Gerald E. Hanks
Organizations
- Naval Radiological Defense Laboratory