(1983). Ionizing Radiation: Sources and Biological Effects. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 43, No. 5, pp. 585-586.

Ionizing Radiation: Sources and Biological Effects

Publisher Summary This chapter reviews cell replacement in epidermis (keratopoiesis) via discrete units of proliferation. Dorsal or ear epidermis from mice is studied. For mouse epidermis, the data indicate that the tissue is subdivided into discrete units of proliferation, each with a certain autonomy but not independent of the neighboring units because they have to interact to produce an effective surface barrier. Each unit is maintained and dependent upon a group of about ten basal cells, one of which would appear to be a stem cell. The size and topographical relationship between the cells is illustrated in the chapter. The chapter also discusses a two-tier proliferative system; with this system, controls may operate at many levels. Any of the controls could potentially be changed; the chapter discusses several related consequences. The rate of progression of the stem cell through the cycle could be altered because of changes in its position or as a consequence of changes in the levels of, or susceptibility to, those factors that may act as on/off switches. Several possible changes might occur in the transit population, which can have dramatic effects on the total cell output.

Cell Replacement in Epidermis (Keratopoiesis) via Discrete Units of Proliferation

LBL~11861 Preprintc MAY 17 LIBRARY AND To be published as a chapter in ADVANCES IN RADIATION BIOLOGY, Spring/Summer 1983, J.T. Lett, ed., Academic Press, New York, NY HEAVY-ION RADIOBIOLOGY: CELLULAR STUDIES Eleanor A. Blakely, Frank Q.H. Ngo, Stanley B. Curtis, and Cornelius A. Tobias February 1983 This a Library Circulating Copy which may be two weeks. a personal Division)' Prepared for the U.S. Department of Energy under Contract DE-AC03-76SF00098

/pdf/heavy-ion-radiobiology-cellular-studies-47x7itexvh.pdf

Heavy-Ion Radiobiology: Cellular Studies

Radiation-induced damage in the central nervous system: an interpretation of target cell responses.

Eighty-three patients (Group A) with parenchymal brain metastases were treated with “rapid-course” whole brain irradiation (1500 rad in 2 treatments) and the results were compared retrospectively with a group of 79 patients (Group B) treated conventionally (approximately 3000 rad in 15 treatments). Neurologic improvement occurred in 57% of patients in Group A and 62.3% of Group B. Median duration of remission was shorter in Group A: 2.0 vs. 3.5 months (p = 0.059); median duration of survival was significantly shorter in Group A: 59 vs. 116 days (p < 0.02) (means: 103 vs. 147 days). Complications were significantly more frequent in Group A: 49.4% vs. 15.2% (p < 0.01). These included acute cerbral herniation (6 cases in Group A, 3 cases in Group B), headache, nausea and vomiting, and fever. The major advantage of the rapid course is the reduction of the period of treatment. Since lethal complications occurred primarily in patients with evidence for markedly elevated intracranial pressure, the “rapid course” should probably be withheld in such patients.

Rapid-course radiation therapy of cerebral metastases: results and complications.

Spinal cords of rats were exposed to either single doses of helium ions ranging from 500 to 3500 rads, or to fractionated doses of helium ions ranging from 1300 to 6530 rads using 10 equal fractions given over 22 days Both plateau and spread-out Bragg peak regions of ionization were used For single doses there was no difference betweenplateau or spread-out Bragg peak ionization regions for production of paralysis; thetolerance dose for production of paralysis was about 1900 rads For the fractionation experiment, there was also no difference between plateau or spread-out Bragg peak ionization regions for production of paralysis; the tolerance dose was between 5220 and 6530rads Comparison of dose levels producing about 10% partial paralysis indicates that about 500 rads of dose is recovered between fractions In both single dose and fractionated experiments, latency between onset of paralysis was between 20 to 24 weeks

Tolerance of the spinal cord of rats to irradiation with cyclotron- accelerated helium ions

(1975). Response of a Rat Brain Tumour to Irradiation with Accelerated Neon Ions. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 28, No. 1, pp. 91-97.

Response of a Rat Brain Tumour to Irradiation with Accelerated Neon Ions

Hind limbs of mice were irradiated to 2500 rad at dose rates of 4.2, 20.9, 73.7, 190.0 and 367.0 rad/min. Early skin reactions were assessed over a period of 1–50 days post irradiation. Skin reactions after 4.2 and 20.9 rad/min were less severe than those at the higher dose rates. At seven months post irradiation, irradiated tissues of surviving mice were evaluated histologically. The 4.2 and 20.9 rad/min groups showed less late damage to tissues than did the higher dose rate groups. At 5 months post irradiation, mice who survived the initial radiation treatment (4.2, 20.9 and 367.0 rad/min groups only) were reirradiated with a single dose of 1500 rad and skin reactions were assessed. Severe skin damage was seen, with a biphasic pattern of temporal development.

Effect of dose rate on production of early and late radiation damage in mouse skin

Clonogenic cell survival of in situ 9L brain tumors was measured in air-breathing rats and rats killed with nitrogen. Animals were irradiated with BEVALAC accelerated carbon ions in the plateau and spread-out Bragg peak regions of the specific ionization curve. The relative biological effectiveness (RBE) for carbon ions in the plateau was 1.2 ± 0.1 for oxic cells and 1.3 ± 0.1 for anoxic cells; in the Bragg peak the RBE was 1.6 ± 0.1 for oxic cells and 2.0 ± 0.1 for anoxic cells. The oxygen enhancement ratio (OER) in the plateau was 2.0 ± 0.1, not significantly different from the 2.1 ± 0.2 found for x rays. The OER in the Bragg peak was reduced to 1.7 ± 0.1. For cells having the same radiobiological sensitivity as in situ 9L cells, the neon ion beam may be therapeutically superior; however, this does not preclude selection of the carbon ion beam in many clinical situations.

Cellular response of a rat brain tumour to a therapeutic neon ion beam.

Survival of mouse-skin epithelial cells after heavy-particle irradiation.

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