THE ACTION OF RADIATION ON MAMMALIAN CELLS
The action of x irradiation on mammalian cells has been studied under carefully controlled conditions in vitro, by means of single cell survival curves, and through direct visualization of the chromosomes after varying doses of radiation. Mammalian cells generally are exceedingly sensitive to destruction of their ability to reproduce, the mean lethal dose, D/sup 0/, for various animal cells varying between 50 and 150r. The normal, diploid human cell exhibits a D/ sup 0/ of 50r, while that for aneuploid hyperploid human cells is about 100r. A variety of independent kinds of evidence establish that the primary radiobiologic action responsible for reproductive death of human cells in these dose rangees is damage to the genetic apparatus, and primarily to the chromosomes. Experiments demonstrate that a dose as little as 20 to 40 r is sufficient to introduce an average of one chromosome break per cell in normal diploid human cells in vitro. These breaks restitute normally if there is only one per cell, and soon leave no visible evidence of their presence. If many breaks are introduced in each cell, abnormal recombinations such as dicentric chromosomes and other aberrations are formed. Analysis of the survival curves demonstrates that some cells, like the normal diploid human cell, are killed reproductively to a significant extent by single-hit events, but that hyperploid aneuploid cells require multiple hits, which produce complex chromosomal forms. The effects of ultraviolet radiation, which produces gene mutations but relatively few chromosome breaks, are readily explaimble by these considerations. By means of the concept of chromosome breakage and the attending destruction of cellreproductive function, it is possible to understand both qualitatively and quamtitatively many of the features of the acute whole body radiation syndrome in mamtaals. (auth)
- Research Organization:
- Univ. of Colorado Medical Center, Denver
- NSA Number:
- NSA-14-006135
- OSTI ID:
- 4195574
- Journal Information:
- Am. Naturalist, Journal Name: Am. Naturalist Vol. Vol: 94
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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