Clippings from Official Journal of the Radiation Research Society Jay H. Lubin and Karen Steindorf Cigarette Use and the Estimation of Lung Cancer Attributable to Radon in theUnited States Epidemiological studies of underground miners exposed to radon suggest that exposure to radon progeny has a greater effect in never-smokers than in smokers. The consequences of this differential effect are examined. Overall, residential radon may cause 13% of all lung cancer deaths in the U.S. Accounting for the differential effect of smoking, the attributable risk of ung cancer may be 9-12% in smokers and 29-31% in never-smokers. . . . . . ..79 A. Leonard, I. Baltus, E. D. Leonard, G. B. Gerber, F. Richard and A. Wambersie Dose-Effect Relationship for In Vivo and In Vitro Induction of Dicentric Aberrations in Blood Lymphocytes of Children The results of this study performed on peripheral blood lymphocytes demonstrate that, in children, in vivo and in vitro exposures to radiation yield similar linear-quadratic dose-effect relationships for dicentric aberrations. No difference was observed between children and adults after in vitro exposure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .95 Gene Induction and Adaptive Responses in Irradiated Cells: Mechanisms andClinical Aspects Montreal, Quebec, Canada, June 3-4, 1994 Thirteen abstracts of presentations made at the meeting in Montreal cover topics such as radiation-induced signal transduction, the effects of low- and high-LET radiations on gene expression, the isolation and characterization of radiation-inducible genes in yeast, the mechanisms of the adaptive response in mammalian cells, activation of gene expression by low-dose radiation, the role of cytokines as mediators of protection and injury from ionizing radiation, and acquired radioresistance. . . . . . . . . . . . . . . . . . . . . . . . . ..108 JAN95 Radiation Research Society, Oak Brook, Illinois, 1995. Philip Hahnfeldt, Lynn R. Hlatky, David J. Brenner and Rainer K. Sachs Chromosome Aberrations Produced by Radiation: The Relationship between Excess Acentric Fragments and Dicentrics This paper uses the observed quantitative relationships between excess acentric and dicentric chromosome aberrations among irradiated human lymphocyte cells to assert how and to what degree radiation-induced chromosome exchanges in humansmay be incomplete. The models proposed are consistent with several observed statistics, e.g., the constancy of the ratio of acentrics to dicentrics with dose, dose rate and possibly LET, and the overdispersion of excess acentrics.................136 FEB95 Gagik G. Gurzadyan, Helmut Görner and Dietrich Schulte-Frohlinde Ultraviolet (193, 216 and 254 nm) Photoinactivation of Escherichia coli Strains with Different Repair Deficiencies Inactivation of E. coli upon irradiation at 193 and 216 nm is due to damage of intracellular DNA. Inactivation of AB2480 (lambda-irr = 254, 216 and 193 nm) is caused by photodimers in the chromosomal DNA, whereas inactivation of AB1157 (193 nm) is due to photoionization. . . . . . . . . . . . . . . . . . . . . . . . . . .244 Elaine Ron, Jay H. Lubin, Roy E. Shore, Kiyohiko Mabuchi, Baruch Modan, Linda M. Pottern, Arthur B. Schneider, Margaret A. Tucker and John D. Boice, Jr. Thyroid Cancer after Exposure to External Radiation: A Pooled Analysis of Seven Studies A study of nearly 700 thyroid cancers and 3,000,000 person-years of follow-up demonstrated a strong linear dose response, even down to 0.10 Gy. Risk decreased significantly with age at exposure, little risk was apparent if exposure occurred after age 20, risk was still elevated 40 years after exposure, and there was a suggestion that spreading dose over time may lower risk. . . . . . . . . . . . . . . . . . . . .259 Yasuhiko Yoshimoto, Haruo Ezaki, Ryozo Etoh, Toshio Hiraoka and Suminori Akiba Prevalence Rate of Thyroid Diseases among Autopsy Cases of the Atomic Bomb Survivors in Hiroshima, 1951-1985 Significant risks were observed in autopsy data for latent thyroid cancer and thyroid adenoma but not for other benign thyroid diseases. Statistical analysis was conducted for possible interactions of age at exposure, sex or observation period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .278 MAR95 Helen A. Weiss, Sarah C. Darby, Tom Fearn and Richard Doll Leukemia Mortality after X-Ray Treatment for Ankylosing Spondylitis In 14,000 ankylosing spondylitis patients treated with X rays, mortality from leukemia other than chronic leukemia was trebled, while there was no significant increase in mortality from chronic lymphatic leukemia, nor was there any increase in leukemia mortality, in 1000 unirradiated spondylitis patients. The dose-response relationship for non-chronic lymphatic leukemia wasdescribed adequately by a linear-exponential model that allowed for cell sterilization in heavily exposed parts of the bone marrow and time since exposure......................................1 APR 95 E. Cardis, E. S. Gilbert, L. Carpenter, G. Howe, I. Kato, B. K. Armstrong, V. Beral, G. Cowper, A. Douglas, J. Fix, S. A. Fry, J. Kaldor, C. Lavé, L. Salmon, P. G. Smith, G. L. Voelz and L. D. Wiggs Effects of Low Doses and Low Dose Rates of External Ionizing Radiation: Cancer Mortality among Nuclear Industry Workers in Three Countries Mortality data on 95,673 nuclear industry workers from Canada, the UK and the U.S. were combined to obtain the most comprehensive and precise direct estimates of the risk of cancer after low-dose protracted exposure to ionizing radiation to date. The results of this study do not suggest that the bases for current radiation protection recommendations are appreciably in error..............................117 MAY95 Geoffrey R. Howe Lung Cancer Mortality between 1950 and 1987 after Exposure to Fractionated Moderate-Dose-Rate Ionizing Radiation in the Canadian Fluoroscopy Cohort Study and a Comparison with Lung Cancer Mortality in the Atomic Bomb Survivors Study Lung cancer mortality as a function of radiation exposure is compared between 64,172 Canadian tuberculosis patients and 75,725 individuals in the atomic bomb survivors study. Despite higher doses, there is no evidence of any radiation-related excess lung cancer in the Canadian study, in contrast to a strong association in the Japanese study, a difference which suggests a substantial fractionation and/or dose-rate effect...................................................................................295 JUN95 F. A. Stewart Radiation Nephropathy after Abdominal Irradiation or Total-Body Irradiation (p. 235) This manuscript reviews the clinical and experimental evidence for radiation nephropathy after abdominal or total-body irradiation. The low limit of renal tolerance and the slowly progressive nature of renal radiation damage are stressed, together with the need to investigate strategies to prevent or ameliorate this damage. R. Chakraborty and K. Sankaranarayanan Cancer Predisposition, Radiosensitivity and the Risk of Radiation-Induced Cancers. II. A Mendelian Single-Locus Model of Cancer Predisposition and Radiosensitivity for Predicting Cancer Risks in Populations (p. 293) This paper presents a genetic model to assess the impact of cancer predisposition and of increased sensitivity of predisposed individuals to radiation-induced cancers. The model is applied to the data for breast cancers in the Japanese A-bomb survivors. SEP95 Adam Lacy-Hulbert, Roger C. Wilkins, T. Robin Hesketh and James C. Metcalfe No Effect of 60 Hz Electromagnetic Fields on MYC or Beta-Actin Expression in Human Leukemic Cells (p. 9) Measurement of MYC and beta-actin expression in human HL60 cells using a novel method for the quantitative Northern analysis of mRNA detected no significant effect of extremely low frequency electromagnetic fields (ELF-EMFs) for exposure periods of up to 1 h to 60 Hz fields of 0.1 to 100 microtesla. Jeffrey D. Saffer and Sarah J. Thurston Short Exposures to 60 Hz Magnetic Fields Do Not Alter MYC Expression in HL60 or Daudi Cells (p. 18) An attempt has been made to validate, under rigorously controlled conditions, key experiments on induction of gene expression by magnetic fields. The results are clearly negative and point to a lack of controls in previous experiments. R. E. Weller, R. L. Buschbom, G. E. Dagle, H. A. Ragan and J. F. Park Hepatic Effects of Inhaled Plutonium Dioxide in Beagles (p. 73) A life-span study of beagles exposed to plutonium dioxide by inhalation reveals that the liver contained 40% of the final body burden of plutonium, second only to the skeleton. This report describes dose-effect relationships for hepatic effects observed for the life span and discusses whether competing risks from bone and lung cancer mask fatal liver cancer. J. R. Johnson, D. K. Myers, J. S. Jackson, D. W. Dunford, N. J. Gragtmans, H. M. Wyatt, A. R. Jones and D. H. Percy Relative Biological Effectiveness of Tritium for Induction of Myeloid Leukemia in CBA/H Mice (p. 82) The RBE of tritium compared to low-energy (150 kVp) X rays for the induction of myeloid leukemia was estimated for male CBA/H mice. The value obtained was less than 1.5, which supports the selection of units for the radiation weighting factor. Kazuo Neriishi, F. Lennie Wong, Eiji Nakashima, Masanori Otake, Kazunori Kodama and Kanji Choshi Relationship between Cataracts and Epilation in Atomic Bomb Survivors (p. 107) The risk of cataract formation per unit dose of radiation in 1713 atomic bomb survivors was significantly greater for those who reported hair loss of 67% or more after exposure (the epilation group) than for those who reported less or no hair loss (the no-epilation group). Although this might be interpreted as indicating differential sensitivity to radiation between the epilation group and the no-epilation group, it could also be explained by a 48% random error in DS86 dose estimates. OCT95 Robert W. Miller Delayed Effects of External Radiation Exposure: A Brief History (p. 160) A history of the development of knowledge about the acute and delayed effects of external radiation exposure from the skin cancer suffered by an early fluoroscope operator to the studies of cancer, mental retardation, genetic effects and other diseases is presented. The panoply of effects and populations studied is discussed. K. Neriishi, S. Akiba, T. Amano, T. Ogino and K. Kodama Prevalence of Hepatitis B Surface Antigen, Hepatitis B e Antigen and Antibody, and Antigen Subtypes in Atomic Bomb Survivors (p. 215) We investigated the active state of hepatitis B virus (HBV) infection in A-bomb survivors by incorporating tests for hepatitis B e antigen and hepatitis B e antibody and HBsAg subtypes into our biennial health examinations of 6548 A-bomb survivors between July 1979 and July 1981. The results suggested that A-bomb survivors remain in an active state of HBV infection and that the mechanism(s) of seroconversion may be impaired. Takeru Minamisawa and Kouichi Hirokaga Long-Term Effects of Prenatal Exposure to Low Levels of Gamma Rays on Open-Field Activity in Male Mice (p. 237) The open-field activity of male mice irradiated with 0.5 or 1.0 Gy of gamma rays on day 14 of gestation changes at 19-20 months but not at 6-7 or 12-13 months. NOV95 Michiko Yamada, Kazunori Kodama, Shoichiro Fujita, Masazumi Akahoshi, Satoru Yamada, Ryoji Hirose and Makoto Hori Prevalence of Skin Neoplasms among the Atomic Bomb Survivors (p. 223) Atomic bomb survivors from Hiroshima and Nagasaki who participate in the Radiation Effects Research Foundation Adult Health Study were examined to define the relationship between skin neoplasms and exposure to ionizing radiation. Odds ratios of skin neoplasm (basal cell carcinoma and senile keratosis) for a 1-Gy dose, occupational exposure to UV rays and age at time of examination (in 10-year increments) are 1.7, 5.9 and 1.9, respectively. Corresponding author: Michiko Yamada; e-mail: michiko_yamada@rerf.or.jp AUG96 Christopher M. Waters, Joann M. Taylor, Agostino Molteni and William F. Ward Dose-Response Effects of Radiation on the Permeability of Endothelial Cells in Culture (p. 321) Endothelial cells cultured on porous microcarrier beads were used in a novel in vitro model to study the mechanisms and modifiers of radiation-induced changes in permeability of the cells under flow conditions using nonradioactive tracers. The results show that the permeability of endothelial cells to low-molecular-weight solutes increases within 3 h after therapeutic doses of radiation. Corresponding author: Christopher M. Waters; e-mail: cwaters@casbah.acns.nwu.edu Yu. N. Korystov, N. A. Eliseeva, L. N. Kublik and A. A. Narimanov The Effect of Low-Dose Irradiation on Proliferation of Mammalian Cells In Vitro (p. 329) Low-dose irradiation (2-20 Gy) stimulates proliferation of cultured mammalian cells due to the shortening of the lag phase of cell growth. Corresponding author: Yu. N. Korystov; e-mail: egorova@venus.iteb.serpukhov.su Masanori Otake, Kazuo Neriishi and William J. Schull Cataract in Atomic Bomb Survivors Based on a Threshold Model and the Occurrence of Severe Epilation (p. 339) A relative risk model with two thresholds, one for the epilation group and the other for the no-epilation group, has been examined using a binomial odds approach and a constant RBE for neutrons of 10. The best model was a linear-linear dose-response relationship with two thresholds. Corresponding author: Masanori Otake; e-mail: otake@stat.ems.okayama-u.ac.jp 3 above from Sep96 B. Marples and K. A. Skov Small Doses of High-Linear Energy Transfer Radiation Increase the Radioresistance of Chinese Hamster V79 Cells to Subsequent X Irradiation (p. 382) This study measured the survival after 1 Gy X irradiation of V79 cells previously irradiated with 0.05-0.2 Gy X rays, neutrons or pions. The results indicate that a protective effect is induced by priming treatments with low- and high-LET radiation and that a threshold level of damage is required for adaptation. Corresponding author: B. Marples; e-mail address: rdbbm@picr.cr.man.ac.uk Lloyd D. Skarsgard, Mark W. Skwarchuk, Bradly G. Wouters and Ralph E. Durand Substructure in the Radiation Survival Response at Low Dose in Cells of Human Tumor Cell Lines (p. 388) Precise measurements of cell survival using the cell sorter assay reveal substructure in the radiation response at doses of a few grays in many asynchronously growing tumor cells. Presumed to be the result of mixed cell populations of different cell cycle phase-dependent radiosensitivity, the substructure can affect determinations of survival parameters substantially. Bradly G. Wouters, Arturo M. Sy and Lloyd D. Skarsgard Low-Dose Hypersensitivity and Increased Radioresistance in a Panel of Human Tumor Cell Lines with Different Radiosensitivity (p. 399) Measurements of survival made with the cell sorter assay reveal a hypersensitivity to radiation doses below 1 Gy, followed by an increase in radioresistance. This phenomenon was observed in the four most resistant of five human tumor cell lines, and it suggests that a dose-dependent alteration in the processing of radiation damage over the initial low-dose region of cell survival may contribute to radioresistance. Corresponding author: Bradly G. Wouters; e-mail address: bwouters@cmgm.stanford.edu Craig Dees, Scott Garrett, Don Henley and Curtis Travis Effects of 60-Hz Fields, Estradiol and Xenoestrogens on Human Breast Cancer Cells (p. 444) Xenoestrogens stimulate breast cancer cells to enter the cell cycle, but 60-Hz fields do not. Therefore, xenoestrogens may be a risk factor for breast cancer and 60-Hz fields may not. Corresponding author: Craig Dees; e-mail address: genase@aol.com ABOVE from OCT96 Yao-Yu Chuang and Howard L. Liber Effects of Cell Cycle Position on Ionizing Radiation Mutagenesis. I. Quantitative Assays of Two Genetic Loci in a Human Lymphoblastoid Cell Line (p. 494) Chemically synchronized WTK1 human lymphoblast cells were irradiated in different phases of the cell cycle. Cells in late G1 to mid-S phase were most sensitive to radiation-induced mutation at the autosomal thymidine kinase locus, while cells in G1 phase were most sensitive at the X-linked hypoxanthine guanine phosphoribosyl transferase locus. Corresponding author: Howard L. Liber; e-mail address: hliber@hsph.harvard.edu Iraimoudi S. Ayene, Cameron J. Koch and Robert E. Krisch Simulation of the Cellular Oxygen Effect with an SV40 DNA Model System Using DNA Strand Breaks as an End Point (p. 501) We have investigated the interaction of a reduced thiol (glutathione) and non-thiol OH radical scavenger (glycerol) in the chemical modification of radiation damage to SV40 DNA in aqueous solution. Similarity between oxygen enhancement ratios (OERs) observed in our in vitro model system and OERs observed in cells by others indicate that non-thiol OH radical scavengers play a major role in the cellular oxygen effect. Corresponding author: Iraimoudi S. Ayene; e-mail address: ayenei@mail.med.upenn.edu J. R. Milligan, C. C. L. Wu, J. Y-Y. Ng, J. A. Aguilera and J. F. Ward Characterization of the Reaction Rate Coefficient of DNA with the Hydroxyl Radical (p. 514) We have measured the second-order rate constant for the reaction of the hydroxyl radical with DNA as a function of the scavenging capacity of the solution. The rate constant increases with increasing scavenging capacity, rising from about 5 x 10^8 dm^3 mol^-1 s^-1 at 10^5 s^-1 to about 10^10 dm^3 mol^-1 s^-1 at 10^10 s^-1. Corresponding author: J. R. Milligan; e-mail address: jamie_milligan@som-bsb.ucsd.edu D. L. Lundgren, F. F. Hahn, W. C. Griffith, A. F. Hubbs, K. J. Nikula, G. J. Newton, R. G. Cuddihy and B. B. Boecker Pulmonary Carcinogenicity of Relatively Low Doses of Beta-Particle Radiation from Inhaled Cerium-144 Dioxide in Rats (p. 525) This study was conducted to examine the carcinogenic effects of chronic beta-particle irradiation of the lung from inhaled beta-particle-emitting radionuclides. We concluded that the linear risk of lung neoplasms was constant at a value of approximately 47 excess lung neoplasms per 10^4 rat Gy over a range of 3.6 to 37 Gy. NOV96 Qiyue Hu and Richard P. Hill Radiosensitivity, Apoptosis and Repair of DNA Double-Strand Breaks in Radiation-Sensitive Chinese Hamster Ovary Cell Mutants Treated at Different Dose Rates (p. 636) The results indicate that low-dose-rate irradiation can differentiate better between the DSB rejoining capacity of sensitive (xrs 5-11 and V3) and resistant (K1 and AA8-4) CHO cells than high-dose-rate irradiation, and they suggest the difference between the cells is in the slow component of DSB repair. Apoptosis induced by high-dose-rate irradiation in 6-11 and K1 cells was found to be dependent on dose, with the level of induction and its time course similar for doses which gave equal levels of clonogenic survival. Corresponding author: Richard P. Hill; e-mail address: hill@oci.utoronto.ca DEC96 Manfred Saran and Wolf Bors Radiation Chemistry of Physiological Saline Reinvestigated: Evidence That Chloride-Derived Intermediates Play a Key Role in Cytotoxicity (p. 70) Hydrogen peroxide and hypochlorite are formed during irradiation of physiological saline. Generation and degradation reactions of both species proceed concomitantly, and the actual reaction paths depend on solution parameters such as oxygen content, rate of hydroxyl radical generation and pH. At slightly acidic pH values, production of the very potent microbicide HOCl is favored and thus determined the radiation-derived cytotoxicity of the solution. Corresponding author: Manfred Saran; e-mail address:saran@gsf.de JAN96 Donald A. Pierce, Yukiko Shimizu, Dale L. Preston, Michael Vaeth and Kiyohiko Mabuchi Studies of the Mortality of Atomic Bomb Survivors. Report 12, Part I. Cancer: 1950-1990 (p. 1) This paper describes the excess cancer risks among atomic bomb survivors followed up by the Radiation Effects Research Foundation in Hiroshima and Nagasaki. It covers the period 1950-1990, updating the previous report by 5 years of additional follow-up. Corresponding author: Donald A. Pierce; e-mail: pierce@rerf.or.jp Charles E. Land, Takashi Saku, Yuzo Hayashi, Osamu Takahara, Hiroo Matsuura, Shoji Tokuoka, Masayoshi Tokunaga and Kiyohiko Mabuchi Incidence of Salivary Gland Tumors among Atomic Bomb Survivors, 1950-1987. Evaluation of Radiation-Related Risk (p. 28) Incidences of both benign and malignant salivary gland tumors among A-bomb survivors were found to be significantly related to radiation dose, with linear model dose-response estimates of relative risk (RR) at 1 Sv equal to 1.7 with 90% confidence limits 1.1-2.7 for benign tumors (based on 64 exposed cases with dose estimates) and 4.5 (2.5-8.5) for malignant tumors (31 cases). By histological subtype, most of the dose response for malignant tumors was contributed by mucoepidermoid carcinoma [11 cases, RR at 1 Sv = 9.3 (3.5-30.6)] and most of that for benign tumors by Warthin's tumor [12 cases, RR at 1 Sv = 4.1 (1.6-11.3)]. Corresponding author: Charles E. Land; e-mail: charles_land@nih.gov Geoffrey R. Howe and Ron H. Stager Risk of Lung Cancer Mortality after Exposure to Radon Decay Products in the Beaverlodge Cohort Based on Revised Exposure Estimates (p. 37) A case control analysis within the Beaverlodge cohort based on revised radon exposure estimates leads to lung cancer mortality risk estimates similar to those reported originally. However, the data no longer show an inverse exposure-rate effect. JUL96 Therese La Vere, David Becker and Michael D. Sevilla Yields of OH Radical in Gamma-Irradiated DNA as a Function of DNA Hydration: Hole Transfer in Competition with OH Radical Formation (p. 673) Carefully measured yields of hydroxyl radical in the hydration layer of DNA at low temperatures show that the hydroxyl radical is found only for hydration levels beyond 9 waters per nucleotide. This suggests that hole transfer to DNA occurs in the inner hydration layer. Geoffrey R. Howe and John McLaughlin Breast Cancer Mortality between 1950 and 1987 after Exposure to Fractionated Moderate-Dose-Rate Ionizing Radiation in the Canadian Fluoroscopy Cohort Study and a Comparison with Breast Cancer Mortality in the Atomic Bomb Survivors Study (p. 694) Breast cancer mortality risks after exposure to low-LET radiation are compared between the Canadian fluoroscopy and atomic bomb survivors studies. The patterns of risk are similar and confirm that the female breast is one of the more sensitive organs to radiation-induced carcinogenesis even with highly fractionated exposures. Hiroshi Inano, Keiko Suzuki, Makoto Onoda and Hiroshi Yamanouchi Susceptibility of Fetal, Virgin, Pregnant and Lactating Rats for the Induction of Mammary Tumors by Gamma Rays (p. 708) The data from this study show a dose dependency of the development of mammary tumors in rats irradiated with 0-2.6 Gy gamma rays in the fetal, virgin, pregnant and lactating groups. Susceptibility of the mammary glands to radiation depends upon the differentiation at the time of exposure. Tej K. Pandita and Charles R. Geard Chromosome Aberrations in Human Fibroblasts Induced by Monoenergetic Neutrons. I. Relative Biological Effectiveness (p. 730) The RBEs of 0.22, 0.34, 1, 5.9 and 13.6 MeV monoenergetic neutrons were determined using chromosome aberrations. The highest RBE (24.3) was found for intrachromosomal deletions at the two lower energies. The radiation weighting factors for neutrons of the energies encountered in high-altitude air travel need better delineation. A. Shirazi, K. Liu and K-R. Trott Exposure to Ultraviolet B Radiation Increases the Tolerance of Mouse Skin to Daily X Irradiation (p. 768) After exposure of mouse skin to UVB radiation, tolerance to single and fractionated doses of X rays increases progressively for 2 weeks. The probable mechanism is an increase in the proportion of stem cells in the epidermis and accelerated repopulation. JUN96 M. R. Raju, M. E. Schillaci, S. G. Carpenter, D. T. Goodhead and J. F. Ward Radiobiology of Ultrasoft X Rays. V. Modification of Cell Inactivation by Dimethyl Sulfoxide (p. 563) Radioprotection against cell killing provided by DMSO is the same for ultrasoft X rays as for cobalt-60 gamma rays, indicating that the proportion of scavengeable damage from these radiations does not depend on the proportion of deposited energy that is associated with low-energy electrons of relatively high ionization density. Marie Lundell and Lars-Erik Holm Mortality from Leukemia after Irradiation in Infancy for Skin Hemangioma (p. 595) No statistically significant increase in leukemia (childhood or adult) could be detected among persons irradiated for skin hemangioma. MAY96 J. R. Milligan, J. A. Aguilera, C. C. L. Wu, J. Y-Y. Ng and J. F. Ward The Difference that Linear Energy Transfer Makes to Precursors of DNA Strand Breaks (p. 442) DNA strand break formation by helium-4 ion irradiation appears to involve intermediate species containing at least two radicals. Elwood P. Armour, Julia R. White, Coleen C. DeWitt, Peter M. Corry and Alvaro Martinez Effects of Continuous Low-Dose-Rate Brachytherapy on the Rectum of the Rat (p. 474) A model to analyze brachytherapy-induced late-occurring injury to the rectum of rats has been developed and tested. The ED-50 for obstruction after 0.75 Gy/h continuous low-dose-rate brachytherapy was 70.6 +/- 42 Gy. David J. Brenner Direct Biological Evidence for a Significant Neutron Dose to Survivors of the Hiroshima Atomic Bomb (p. 501) It is suggested that the F value, which is the ratio of translocations to pericentric inversions, is smaller in the cells of those exposed in Hiroshima than would be expected from exposure to gamma rays. If this is so, the contribution of neutrons is greater than has been assumed and the risk coefficient for gamma rays may have been overestimated. APR96 Ethel S. Gilbert, Fred T. Cross and Gerald E. Dagle Analysis of Lung Tumor Risks in Rats Exposed to Radon (p. 350) Using data on 3117 rats exposed by inhalation to radon and radon progeny, the hazard function (or age-specific risk) for lung tumor incidence was modeled as a function of exposure, exposure rate and other factors with special attention to investigating the possibility of an inverse exposure-rate effect. Evidence for such an effect was limited primarily to cumulative exposures exceeding 1000 WLM (1280-10,240 WLM) and to comparison of results at 100 and 1000 WL, with little evidence of such an effect for exposures in the range 20-640 WLM. B. A. Muggenburg, R. A. Guilmette, J. A. Mewhinney, N. A. Gillett, J. L. Mauderly, W. C. Griffith, J. H. Diel, B. R. Scott, F. F. Hahn and B. B. Boecker Toxicity of Inhaled Plutonium Dioxide in Beagle Dogs (p. 361) Plutonium inhaled as plutonium-238 dioxide was more soluble in body fluids than plutonium-239 dioxide, leading to significant depositions of plutonium-238 in liver and skeleton as well as lung. Life-span observations of these animals showed early-occurring deterministic effects in the lung and blood of the animals receiving the highest exposures and dose-related tumors in the lung, liver and bone at lower exposure levels. MAR 96 E. Georg Luebeck, Stanley B. Curtis, Fred T. Cross and Suresh H. Moolgavkar Two-Stage Model of Radon-Induced Malignant Lung Tumors in Rats: Effects of Cell Killing (p. 163) A two-stage model of carcinogenesis is used to analyze lung tumor incidence in rats exposed to varying regimens of radon. This analysis presents evidence that a two-stage model adequately describes the data and generates a hypothesis regarding the mechanism of radon-induced carcinogenesis. J. A. Simmons, P. Cohn and T. Min Survival and Yields of Chromosome Aberrations in Hamster and Human Lung Cells Irradiated by Alpha Particles (p. 174) Using the end points of cell death and the induction of chromosome aberrations, human cells have been shown to be twice as sensitive as Chinese hamster V79 cells to the effects of alpha-particle irradiation. Marie Lundell, Anders Mattsson, Timo Hakulinen and Lars-Erik Holm Breast Cancer after Radiotherapy for Skin Hemangioma in Infancy (p. 225) Women irradiated for skin hemangioma during infancy show from the age of 40 an increased breast cancer risk that is significantly elevated more than 50 years after radiotherapy. FEB96 Per Hall, Anders Mattsson and John D. Boice, Jr. Thyroid Cancer after Diagnostic Administration of Iodine-131 (p. 86) No increased risk of thyroid cancer related to ionizing radiation was found in 34,104 individuals exposed to diagnostic doses of iodine-131. JAN96 Werner Burkart, Bernd Grosche and Angela Schoetzau Down Syndrome Clusters in Germany after the Chernobyl Accident (p. 321) In two independent studies using different approaches and coving Berlin and Bavaria, Germany, respectively, significant temporal clusters of Down syndrome were found which had close temporal correlation. Only for the Berlin cluster was fallout present at the time of affected meiosis, whereas the Neuremberg cluster preceded the radioactive contamination by 1 month Correspondence to Werner Burkart:burkart@bfs.de Robert J. Walter, Alexander A. Schtul, Igor B. Roninson and Oksana Holian 60-Hz Electric Fields Inhibit Protein Kinase C Activity and Multidrug Resistance Gene (MDR1) Up-Regulation (p. 369) Exposure of H9 human leukemia cells to intermediate-strength 60-Hz electric fields inhibits cytosolic protein kinase C activity and AraC-induced MDR1 gene expression. Data supporting a hypothesized mechanism linking the observed effects of electric fields on cytosolic PKC activity to the changes in the activation of MDR1 gene expression are also presented. Correspondence to Robert J. Walter:rwalter@sispro.sis.rpslmc.edu Robert R. Delongchamp, Kiyohiko Mabuchi, Yasuhiko Yoshimoto and Dale L. Preston Cancer Mortality among Atomic Bomb Survivors Exposed In Utero or as Young Children, October 1950-May 1992 (p. 385) Cancer mortality for the period from October 1950 through May 1992 was analyzed in atomic bomb survivors exposed in utero. There was an excess risk from exposure that was seen primarily in females Correspondence to Dale L. Preston:preston@rerf.or.jp Robert W. Miller and John D. Boice, Jr. Cancer after Intrauterine Exposure to the Atomic Bomb (p. 396) For 807 A-bomb survivors exposed In Utero (71 to doses over 0.50 Sv), the cancer experience did not differ statistically from that of survivors exposed at age 0-5 years. However, on the basis of biological considerations (e.g. radiation inducibility of the cancers), the evidence concerning an excess of cancer is meager, but should improve as the cohort ages. Correspondence to Robert W. Miller:millerr@epndce.nci.nih.gov above from FEB97