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Biomedical subjects

E L POWERS

Publications and source records attributed to E L POWERS.

At least 19 recordsLinked to original sources
PubMed1960

Thermal annealment and nitric oxide effects on free radicals in x-irradiated cells.

Four kinds of radicals are identified in dry spores (Bacillus megaterium) after x-irradiation: those associated with singlet, doublet, triplet, and oxygen-complex types of spectra. The singlet, present only at low temperatures, gives rise irreversibly to the doublet at 25 degrees C. All hyperfine structure is depressed after annealment at 1000 degrees C and is lost when oxygen or nitric oxide is added. The physical results support the hypothesis that reactions of long-lived free radicals can account for the radiobiological phenomena of thermorestoration, nitric oxide protection, and latent oxygen effect.

Free Radicals↗
PubMed1960

Reduction of radiation sensitivity of dry bacterial spores with hydrogen sulfide.

Hydrogen sulfide redtuces the lethal effect of x-rays in dry spores by about 50 percent when given after irradiation, and by approximately 75 percent when present during irradiation. The first effect is the result of removal of radicals that are toxic when combined with oxygen; the second, the removcal of radicals that become toxic in the absence of oxygen. With these results we construct an explanation of the action of sulfhydryl compounds in protection against radiation damage.

Bacteria↗
PubMed1960

The effects of x-rays and beta rays (tritium) on the growth of Rickettsia mooseri and Rickettsia akari in embrvonate eggs.

The growth of Rickettsia mooseri was accelerated and quantitatively increased in embryonate eggs containing tritium oxide at levels of 180, 90, and 45 mc./egg during the growth period. The eggs of a group containing 22.5 mc./egg showed only a slight increase in the rate of growth of organisms; the infections in the eggs of a group given 11.2 mc./egg did not differ significantly from those of the control group. On the other hand, growth of R. akari was inhibited in embryonate eggs containing tritium oxide at levels of 180, 90, and 45 mc./egg, and partially inhibited in groups containing 22.5 and 11.2 mc./egg. The patterns of growth of R. mooseri and of R. akari exposed to tritium oxide for 6 hours prior to inoculation into embryonate eggs did not differ significantly from that of the control group. Single and divided doses of x-rays to the host resulted in partial inhibition of the growth of R. akari.

Beta Particles↗
PubMed1957

Further studies on the effects of x-radiation on the multiplication of Rickettsia mooseri in embryonate eggs.

The effect of x-rays on the growth of rickettsiae in the embryonate egg was investigated. The intensifying effect of x-radiation of the host on rickettsial growth can be attributed to alterations of the cells of the host that persist at least 7 days. The greatest enhancement of the growth of rickettsiae occurred when moderately infected cells were irradiated. These experiments indicate that x-rays may neutralize or reverse changes in the host that are unfavorable to the growth of rickettsiae. Explanations of the observed phenomena in terms of biochemical and biological alterations of the cells of the host are discussed.

Rickettsia↗
PubMed1957

The effect of x-rays on the rickettsiostatic activity of streptomycin, aureomycin, and penicillin.

The effect of x-rays on the rickettsiostatic activity of streptomycin, penicillin and aureomycin in the embryonate egg was investigated. Only a slight reversal of the rickettsiostatic action of 5 mg. of streptomycin occurred in embryonate eggs given 100 r of x-rays at 4 days of incubation, whereas complete reversal occurred in those given 1000 r. Groups of eggs irradiated with intermediate doses of x-rays showed a graded response. The rickettsiostatic activity of 5 mg. (1660 Oxford units/mg.) of penicillin or of 5 mg. of aureomycin was not reversed by doses of x-rays ranging from 100 to 1000 r. 500 r of x-rays reversed the rickettsiostatic activity of 2 mg., 4 mg., 8 mg., or 16 mg. of streptomycin per egg in proportion to the amount of streptomycin injected. The rickettsiostatic activity of 2 mg. of streptomycin was completely reversed and the activity of 16 mg. only partially reversed. Reversal of the rickettsiostatic activity of streptomycin by x-rays was observed when radiation was given up to 6 days after the injection of the antibiotic into 7-day-old embryos. Reversal of the rickettsiostatic activity of 4 mg. of streptomycin could be detected when the antibiotic was injected 3 days after 500 r of x-radiation. Explanations of the observed phenomena are discussed in terms of biochemical and biophysical alterations of the cells of the host.

Anti-Bacterial Agents↗