Military Medicine

PhD, E. John Ainsworth,

doi: 10.1093/milmed/167.suppl_1.vipmid: N/A

This content is only available as a PDF. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, Thomas M. Seed,

doi: 10.1093/milmed/167.suppl_1.viiipmid: N/A

This content is only available as a PDF. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

USA, Robert R. Eng, MS,

doi: 10.1093/milmed/167.suppl_1.viipmid: N/A

This content is only available as a PDF. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, William F. Blakely,;van der Schans, PhD, Govert P.

doi: 10.1093/milmed/167.suppl_1.1pmid: N/A

This content is only available as a PDF. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, James Z. Xing,;MSc, Jane Lee,;PhD, Steven A. Leadon,;PhD, X. Chris Le,;PhD, Michael Weinfeld,

doi: 10.1093/milmed/167.suppl_1.2pmid: N/A

Abstract We previously described a sensitive assay for measuring thymine glycol in the DNA of irradiated cells. The assay combines immunorecognition of the DNA lesion with capillary electrophoresis and laser-fluorescence detection to achieve an absolute detection level in the zeptomole (10−21 mol) range. This article describes modifications to the protocol that overcome certain technical problems seen with the original methodology. In particular, the capillary electrophoresis is carried out at pH 8.3 rather than pH 10.5. The new protocol was used to examine removal of thymine glycol from the DNA of A549 lung adenocarcinoma cells and resting lymphocytes after exposure to 2 Gy γ rays. Both cell types displayed similar repair kinetics. Removal of thymine glycol is almost complete at 4 hours postirradiation. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

van der Schans, PhD, Govert P.;BSc, Arie J. Timmerman,;PhD, Pieter L.B. Bruijnzeel,

doi: 10.1093/milmed/167.suppl_1.5pmid: N/A

Abstract An immunochemical assay has been adapted to detect DNA damage in whole blood at biologically relevant doses of ionizing radiation. Upon alkaline treatment of whole blood, both strand breaks and base damage (which is converted into strand breaks by the addition of damage-specific enzymes) are detected by using antibodies that specifically bind to single-strand DNA. Single-strand breaks can be detected immediately after irradiation at doses as low as 0.2 Gy. With unknown background damage, the lower detection limit increased to approximately 0.5 Gy immediately after irradiation due to interindividual variation. Because single-strand breaks are repaired rapidly, this method is suitable only for blood collected less than 1 hour after exposure. Base damage represents a very promising biological indicator that can be used 1 hour and longer (at least to 4 hours) after radiation exposure because of an apparent lack of base damage repair during this time window. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, James D. Tucker,

doi: 10.1093/milmed/167.suppl_1.8pmid: N/A

Abstract The analysis of chromosome translocations by fluorescence in situ hybridization (“whole chromosome painting”) is the gold standard endpoint for radiation biological dosimetry. Translocation formation requires mis-repair of two or more DNA double-strand breaks, a critical class of damage that is efficiently induced by ionizing radiation in a dose-responsive manner. Translocations are widely used for radiation exposure assessment because they provide a sensitive detection system for low doses, show good specificity for radiation exposure, persist for decades, and are highly relevant to tumorigenesis. This paper provides a brief evaluation of the use of translocation analyses by chromosome painting for biological dosimetry following chronic or low-dose exposure to ionizing radiation. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, Pataje G.S. Prasanna,;BS, Christine J.C. Hamel,;USN, Nestor D. Escalada, MSC,;USN, Keife L. Duffy, MSC,;PhD, William F. Blakely,

doi: 10.1093/milmed/167.suppl_1.10pmid: N/A

Abstract Conventional metaphase-spread chromosome-aberration-based biodosimetry techniques for radiation dose assessment, although robust, are laborious and time consuming. The molecular cytogenetic laboratory of the Armed Forces Radiobiology Research Institute is developing simple and rapid interphase-based cytological assays that will be applicable to a broad range of radiation exposure scenarios. These assays include analysis of chromosome aberrations (premature chromosome condensation-fluorescence in situ hybridization assay) and mitochondrial DNA mutations (mtDNA4977 deletion assay) using resting human peripheral blood lymphocytes. The dose-effect relationship for radiation-induced aberrations involving chromosome 1 after 24 hours of repair at 37°C in resting human peripheral blood lymphocytes was studied using fluorescence in situ hybridization after chemical induction of premature chromosome condensation as previously explained. In the present study, we examined whether gamma irradiation in the range of 0 to 7.5 Gy induces a dose-dependent increase in aberrations manifested as “excess spots.” The number of excess spots per cell, reflecting aberrations involving chromosome 1, increased from 0.035 at 0.5 Gy to 0.236 at 7.5 Gy. This observed dose-effect relationship was fit with a nonlinear power model. This technique may be extended to the study of radiation-induced translocations in interphase cells for retrospective dose reconstruction. With a recently developed in situ polymerase chain reaction method to detect and quantify mtDNA deletion in interphase cells after radiation exposure in cultured human peripheral blood lymphocytes, 90% to 95% of cells are analyzable. We discuss the potential use of the mtDNA deletion assay in biological dosimetry applications. Interphase-based cytological assays may eliminate some inherent problems associated with metaphase-spread-based assays. These problems involve (1) the limited number of analyzable cells containing chromosome aberrations, which is due to various factors including radiation-induced cell death and delay in cell cycle progression into mitosis, and (2) the requirements for radiation cytogenetics expertise and tedious labor to manually score chromosome aberrations. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, Sally A. Amundson,;MSc, Khanh T. Do,;PhD, Paul Meltzer, MD;PhD, Jeffrey Trent,;PhD, Michael Bittner,;PHS, Albert J. Fornace, Jr.,

doi: 10.1093/milmed/167.suppl_1.13pmid: N/A

Abstract Using a human myeloid tumor cell line (ML-1), we detected induction of mRNA expression of several stress-responsive genes by doses of gamma rays as low as 2 cGy. For instance, the dose response for induction of CIP1/WAF1 and GADD45 appears to be linear over the range of 2 to 50 cGy and shows no evidence of a threshold for induction. Although 2 and 5 cGy exposures did not result in any detectable reduction in cloning efficiency nor in increased apoptosis in ML-1 cells, these exposures did produce a brief cell-cycle delay. We also used fluorescent cDNA microarray hybridization to investigate transcriptional stress responses following low doses of gamma rays and to identify additional radiation-responsive genes for inclusion in a stress-specific microarray we are developing. These studies provide insight into the molecular responses to physiologically relevant doses, which cannot necessarily be extrapolated from high-dose studies. The use of high throughput arrays will allow the identification of multiple stress-responsive genes that are radiation inducible in a variety of cell types and tissues. The expectation is that transcriptional stress responses will provide a molecular approach to monitoring for radiation exposure and detecting interindividual differences. Reprint & Copyright © by Association of Military Surgeons of U.S., 2002

PhD, William F. Blakely,;PhD, Alexandra C. Miller,;PhD, Luo Lei,;USNR, Jason Lukas, MSC,;Hornby, Zachary D.;Hamel, Christine J.C.;USAF, Joseph T. Nelson, MSC,;USN, Nestor E. Escalada,;PhD, Pataje G.S. Prasanna,

doi: 10.1093/milmed/167.suppl_1.16