Genetics of human cell lines. III. Incorporation of 5-bromo- and 5-iododeoxyuridine into the deoxyribonucleic acid of human cells and its effect on radiation sensitivity

Sulfur mustard: reaction with L-cells treated with 5-fluorodeoxyuridine

After exposure to 5-fluorodeoxyuridine, L-cells are considerably more sensitive to the lethal effect of sulfur mustard than after they have been released from this block by addition of thymidine and allowed to proceed into the G2 phase of the division cycle. Nevertheless, for both populations, the amounts of mustard bound per cell and per nucleus (expressed as the amount of mustard per unit of protein) were the same. Likewise, the amounts of mustard bound per unit of DNA were the same for both populations.

Suppression of delayed hypersensitivity in vitro by inhibition of protein synthesis

Peritoneal cells from guinea pigs exhibiting delayed hypersensitivity are inhibited from migrating in vitro by specific antigen. This inhibition is prevented by the addition of puromycin to the culture medium. The amount of puromycin necessary to prevent the inhibition by antigen also suppressed the incorporation of C(14)-leucine into peritoneal cell protein. Additional evidence that the action of puromycin is due to its inhibition of protein synthesis has been obtained with analogues of puromycin; those that inhibit protein synthesis also prevent the action of antigen on the cells, while those analogues that do not inhibit protein synthesis have no effect. Actinomycin also prevents the inhibition of sensitive cells by antigen while chloramphenicol has no effect. The data indicate that the inhibition of sensitive cell migration by antigen requires active protein synthesis. The possible mechanisms by which inhibition of protein synthesis may influence the in vitro reactions of delayed hypersensitivity are discussed.

Bromine Analysis in 5-Bromouracil-Labeled DNA by X-ray Fluorescence

The degree of replacement of thymine by 5-bromouracil in the deoxyribonucleic acid (DNA) of the thymine-deficient bacterium Escherichia coli B 15 T(-) has been determined by a nondispersive x-ray fluorescence method. A measure of the fraction by weight of bromine in the purified DNA is required for determining the degree of thymine replacement. This fraction is experimentally determined on 35-microg samples of DNA by x-ray spectroanalysis.

RADIOTHERAPY OF GLIOMATA: CLINICAL AND BIOLOGICAL FACTORS

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Synergistic Effect of 5-Bromodeoxyuridine and Gamma Rays on Chromosomes

The combined effect of 5-bromodeoxyuridine and gamma rays on chromosomes in cells from the root tips of Zebrina pendula is synergistic. The enhanced, combined effects per cell of aberrations, bridges, and acentric fragments were, respectively, 2, 2.4, and 1.9 times the sum of the separate effects.