The Relation Between Age and Radiosensitivity of<i>Drosophila</i>Eggs

Packard, Charles

doi:10.1148/25.2.223

Cited by 26 publications

(6 citation statements)

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“…The concentration of the reduced form of this thiol in the blood was 1oo mg. percent 15 minutes post-injectionem and remained high for one hour. In the aqueous humor 30 mg. percent was measured five minutes after the medication and did not increase in the following 25 minutes.…”

Section: Resultsmentioning

confidence: 97%

“…The investigations of Packard (25), Wood and Prime (26), Strangeways and Fell (27), and others, indicated that environmental factors introduced after radiation could have an important influence on the effect of Xrays on biological material. In the same vein, a prolongation of survival times among radiated mice was recorded by Goldfeder and co-workers (13) when folic acid and pyridoxin hydrochloride were administered not only before radiation but for several weeks 397 thereafter.…”

Section: Effect Of Thiols On X-ray Cataractmentioning

confidence: 99%

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Further Efforts to Influence X-Ray Cataract by Chemical Agents

Sallmann¹

1952

Archives of Ophthalmology

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Section: Resultsmentioning

confidence: 97%

Section: Effect Of Thiols On X-ray Cataractmentioning

confidence: 99%

Further Efforts to Influence X-Ray Cataract by Chemical Agents

Sallmann¹

1952

Archives of Ophthalmology

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“…The reaction of Drosophila eggs to beams of low intensity has been observed over a period of years (18). The total number of tests to determine the relation between the dose, measured in roentgens, and the percentage of survivors is now upwards of 250.…”

Section: Methodsmentioning

confidence: 99%

“…The effect of divided doses of high intensity x-rays can be tested to only a limited extent on these eggs because their sensitivity changes rapidly and at a rate which is not constant (18). An experiment cannot safely be prolonged beyond twenty or thirty minutes.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Single and Divided Doses of High Intensity X-Rays on the Eggs of Drosophila

Packard¹

1937

The American Journal of Cancer

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The many studies on the relation between the intensity of radiation and the magnitude of the biological reaction indicate that in a majority of cases high intensities and brief exposures are more effective than low intensities and correspondingly long exposures; and that single doses are more effective from the biological point of view than divided doses. The opinion is sometimes expressed or implied that experimental results which point to an opposite conclusion are probably wrong. In the literature, reviewed by Griffith and Zimmer ( 7 ) Pack and Quimby (16), and Schreiber (20), may be found many instances of experiments in which the same test objects and technic were used and yet the results were contradictory. Ascaris eggs, exposed in air, are reported to be less affected by divided doses than by a single massive dose (13, 81, and again to be more affected (23). Exposed in an atmosphere deprived of its oxygen, these eggs show a simple cumulative effect of repeated doses (8) ; that this treatment may produce a greater reaction than that which follows a single dose is also claimed ( 1 1).The behavior of tissue culture cells under different conditions of dosage is also under dispute. Faber (6) states that the mitotic rate is equally retarded whether the dose is given at high or low intensities or in fractions, while others (1, 22) believe that high intensities are the more effective and that divided doses produce a greater reaction than single large doses. Drosophila eggs, according to Sievert and Forssberg (2 I ) , respond equally to all intensities of x-rays within a very wide range; but Roesler and Henshaw (19) find that high intensities are more effective than low.Errors in technic may account for some of these conflicting results; but without doubt many of the observed differences are real, and may be related to differences in the physiological condition of the test objects at the time of exposure. A review of some of the physical and biological conditions which must be considered when carrying out experiments of this kind may make clear why uniformity in results cannot be expected.The terms " low " and " high " intensity are purely relative. What constitutes a low or subminimal intensity for any particular material cannot be predicted; it must be determined by experiment. Radiations received at the rate of 0.04 r/hour by the human skin are ineffective, no matter how long the exposure may be (15). At the other extreme are some Protozoa which are not injured by enormous doses repeated daily. As the intensity rises above a certain minimum, whose value varies widely in different kinds of cells and tissues, the effect produced often becomes proportional to the dose within a wide range of intensities and periods of exposure. The epilation dose

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“…The ''Receptor Theory 99 Yet despite these ordered advances in what we might term the analytical approach to the nature of drug action, the bulk of existing pharmacological data can be interpreted only by assuming that drugs combine with hypothetical "receptors" in the living organism to produce similar or antagonistic responses.…”

Section: Applied Biophysicsmentioning

confidence: 99%

Applied biophysics; survey of physical methods used in medicine , a symposium.

Howard‐Jones¹

1949

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The Relation Between Age and Radiosensitivity ofDrosophilaEggs

Cited by 26 publications

References 0 publications

Further Efforts to Influence X-Ray Cataract by Chemical Agents

Further Efforts to Influence X-Ray Cataract by Chemical Agents

The Effect of Single and Divided Doses of High Intensity X-Rays on the Eggs of Drosophila

Applied biophysics; survey of physical methods used in medicine , a symposium.

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