Outstanding Accuracy
Hope Gains for Radiation Poisoning Survival Immediate chemical treatment may prevent irradiated cells from producing abnormal genes
M
EDICAL
research
has
cleared
another rock from the road to curing radiation poisoning. Recent findings indicate t h a t radiation poisoning c a n be curbed by chemical treatment—if the treatment comes soon enough. This doesn't mean that there is n o w a super-expressw a y t o a sure cure. Unfortunately, intense radiation damages cells beyond repair a n d nothing can be done about it. But a new understanding of a chemical "chess g a m e " which takes place within cells m a y eventually m a k e it possible to salvage m a n y radiation-damaged cells. Felix L. H a a s a n d Charles O . Doudney, biologists a t T h e University of Texas M . D . Anderson Hospital a n d T u m o r Institute in Houston, were studying the process of gene synthesis. Using ultraviolet light, H a a s a n d D o u d n e y found that radiation affects, n o t t h e genes, b u t certain " r a w " chemicals which assemble in the cell to produce the all-important nucleic acids in t h e genes. These r a w chemicals a r e purines a n d pyrimidines. T h e nucleic acids a r e R N A a n d D N A (ribose nucleic acid and deoxyribose nucleic acid).
T h e r e is a time lapse between irradiation a n d t h e time t h e d a m a g e d chemicals assemble to produce t h e a b n o r m a l genetic structure. I t takes a b o u t 30 minutes for genetic D N A and R N A to be m a d e in the cells. But, if a chemical " c h e c k m a t e " is absorbed after irradiation, it will keep t h e cell from producing D N A and R N A for as long as a n hour. I n their work with bacteria H a a s a n d Doudney used chloramphenicol. I t would not work for the same purpose in h u m a n s , however. After a n hour, when the chemical is diluted out, t h e cells g o back to their normal synthetic mechanisms— without abnormal changes or m u t a tions. A n enzymatic process consumes t h e d a m a g e d purines a n d pyrimidines a n d they a r e n o longer available to h a r m t h e cell. T h e biologists did their work in
bacteria, because synthetic processes can be studied more closely with bacteria t h a n in higher forms. O t h e r investigations, however, h a v e shown that t h e mutation induction is t h e same. T h e r e a r e also indications that the effect is the same whether the radiation be ultraviolet or ionizing. If this is true, then theoretically, a m a n w h o received a large dose of radiation could be given quick treatment with chemicals to halt the action of abnormal D N A a n d R N A precursors.
PALMER Dial Thermometer
A n unusual relationship between mutation frequency a n d radiation dose led H a a s a n d Doudney to their discoveries. M u t a t i o n frequency increases with dose rate until it eventually reaches a plateau. A t still higher radiation doses, it starts declining. T h e researchers reasoned t h a t there must be some substance in t h e cells which is changed by r a diation b u t is limited in amount. T h e y began beefing u p their bacteria with materials which are known to produce D N A a n d R N A — a n d the chief ones a r e purines a n d pyrimidines. Even with this special diet, the cells behaved normally. But ultraviolet radiation did t h e trick. T h e mutation frequency increased. This put t h e " c u l p r i t " tag on the purines and pyrimidines. T h e next step was to find a n d inhibitor to keep the cells from producing abnormal n u cleic acids. Chloramphenicol filled the bill. Left in a culture of irradiated bacteria for 15 minutes, the chloramphenicol stopped some, but not all, of the a b n o r m a l changes. After a n hour, however, there were virtually n o mutations. T h e radiation damaged nucleic acid precursors h a d been used u p — p r o b a b l y in some enzymatic process. These findings a r e significant in more ways than just radiation poisoning. Besides offering a better u n derstanding of gene synthesis itself, they m a y also have a bearing on the study of cancer.
MODEL 1035
Check these functional features • Direct-drive Bourdon Coil with a filled system for longer lasting accuracy. • Stem can be placed at any desired angle and case can be rotated to most readable position. • External calibration for zero setting. • Unaffected by stem alignment. • Accurate to one scale division. • No sticking at any temperature. •
Non-corrosive case.
PALMER
THERMOMETERS, I N C . M f r s . o f Industrial Laboratory, Recording a n d Dial Thermometers . 2 5 1 5 N o r w o o d A v e . , Cincinnati 1 2 , O . VOL.
50, NO. 5 ·
MAY 1958
33 A
