Figure 1. This figure illustrates a complex exchange that originated from four chromosome breaks; one each from the yellow and red chromosomes and one in each arm of the blue chromosome. This exchange was formed by one of two possible rejoining pathways. The first illustrated on the left shows the possibility where the exchange could have been formed by two separate rejoining events termed cycles. As illustrated here, one cycle accounts for the exchange between the yellow chromosome and the upper arm of the blue chromosome. Likewise, the second cycle involves the red chromosome with the lower arm of the blue chromosome. We designate this cycle structure c2 + c2 (i.e. two cycles, each forming from two breaks). The other possibility is that the exchange might have formed following the pathway on the right where all the breaks participate in the same rejoining cycle (c4). This becomes an issue with the Break Too Far hypothesis since with the c2 + c2 scenario; the "green” cycle is independent from the "white” cycle. While the breaks within a c2 cycle must be proximate; they may be sufficiently distant from the breaks of the other cycle to disallow any rejoining between them. This situation can be imagined as two simple exchanges that share a common chromosome. Under these conditions, any open breaks cannot result from a Break Too Far mechanism. With the c4 scenario, the breaks cannot interact independently from one another and Break Too Far type open breaks are a possibility. The problem is, unless we have additional information beyond that provided by mFISH it is impossible to determine which pathway was followed; c2 + c2 or c4. It is also important to note that any exchange that can be broken down into separate cycles might potentially have originated from a single rejoining cycle. Complex exchanges that can be broken down into multiple cycles are termed sequential exchange complexes (SEC).

Figure 2. In some cases, only one rejoining pathway is possible as illustrated here. This scenario is said to have a "full” cycle structure. From the drawing it can easily be seen how, on occasion breaks may be too far apart to misjoin. Here, the centromeric portion of the yellow chromosome might be too far away from the acentric portion of the green chromosome to allow them to join (reaction 4) even though all the other breaks ends involved in the exchange are proximate with their partners. This is the essence of the Break Too Far Hypothesis.

We reasoned, if the Break Too Far Hypothesis is correct, then the likelihood that an exchange would be incomplete (i.e. have an open break associated with it) would increase with the number of breaks associated with it. The fact that this type of analysis would be complicated in SECs prompted us to use non-sequential exchange complexes with full cycle structures for this determination, the results of which are plotted in fig. 3 of our paper (see the text there for further details).

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The December 2012 podcast features an interview with Ross Berbeco, lead author of the paper entitled DNA Damage Enhancement from Gold Nanoparticles for Clinical MV Photon Beams appearing in the December 2012 issue of Radiation Research. The interview is hosted by Marjan Boerma and covers the key aspects of Dr Berbeco's work, and that of his co-authors, touching on the value of using gold in the context of MV x ray-based therapies, as well as photon beams of lower energies, and on the in vivo problematic of these types of targeted approaches.

The November 2012 podcast features an interview with Michel Scholtz from GSI Darmstadt, Germany, senior author of the paper entitled Modeling Cell Survival after Photon Irradiation Based on Double-Strand Break Clustering in Megabase Pair Chromatin Loops appearing in the November 2012 issue of Radiation Research. The interview is hosted by Massimo Pinto and touches on the research efforts of Michael Scholtz, and his colleagues, who have been focused for a long time toward a deeper understanding of the biological effects of high linear energy transfer radiations that are used in cancer therapy with accelerated ion beams. Their more recent work that Michael Scholtz describes in this interview focuses on modeling the biological impact of clustered vs isolated DNA double strand breaks induced by photon irradiation, as a means to better understand some complexities that have emerged in their earlier investigations with high-LET radiation.

Our October 2012 podcast features an interview with Dr. Richard Britten, senior author of the paper entitled Executive Function in Rats is Impaired by Low (20 cGy) Doses of 1 GeV/u 56Fe Particles. The interview is hosted by Erik Young.

Our September 2012 podcast features an interview with Dr John Lazo, senior author of the paper entitled Identification of Druggable Targets for Radiation Mitigation Using a Small Interfering RNA Screening Assay. The interview is hosted by Marjan Boerma.

This month's featured interview by Sylvain Costes was conducted at the Society's annual meeting in Puerto Rio and covers an article that was published in the July issue of the Journal, Effects of Radiation and Lifestyle Factors on Risks of Urothelal Carcinoma in the Life Span Study of Atomic Bomb Survivors. The speaking author is Dr. Eric Grant from the RERF, pictured here before the Hiroshima atomic doe peace memorial.

Erik Young offers a summary of conference proceedings and speaks with conference organizer Dr. Tom Hei.

Sylvain Costes interviews John Moulder on his recent contribution in risk assessment of airport scanners, and how he got to know about what he wrote in his commentary paper appearing in the June issue of Radiation Research entitled Risks of Exposure to Ionizing and Millimeter-Wave Radiation from Airport Whole-Body Scanners. This paper was written after John Moulder presented it at the American Association of Physicists in Medicine (AAPM) meeting in Vancouver in 2011.

Drs Vivek Kumar and Sehadri are authors, with Dr Cheriyan, of the paper Evaluation of Spontaneous DNA Damage in Lymphocytes of Healthy Adult Individuals from High-Level Natural Radiation Areas of Kerala in India. Their interview is jointly hosted by Marjan Boerma and Massimo Pinto.

Our March 2012 podcast features an interview with Dr. Eric. G. Wright, senior author of the paper entitled Bystander-Type Effects Mediated by Long-Lived Inflammatory Signaling in Irradiated Bone Marrow. Dr. Wright is located at the Centre for Oncology and Molecular Medicine at the University of Dundee Medical School in Scotland. The interview is hosted by Marjan Boerma.

Our February 2012 podcast features an interview with Dr. Jamie Milligan, senior author of the paper entitled Modeling the Influence of Histone Proteins on the Sensitivity of DNA to Ionizing Radiation. The interview is hosted by Sylvain Costes.

Our January2012 podcast features an interview with Isabelle Thierry-Chef, first author of the paper entitled Reconstruction of Absorbed Doses to Fibroglandular Tissue of the Breast of Women Undergoing Mammography (1960 to the Present), together with her co-author Steven Simon. The interview is hosted by Marjan Boerma.

Our November 2011 podcast features an interview with Siegal Sadetzki and Angela Chetrit, co-authors, with other colleagues both in Israel and the USA, of the paper entitled Childhood Exposure to Ionizing Radiation to the Head and Risk of Schizophrenia. The interview is hosted by Massimo Pinto.

Linked to the subject of this interview, and coming up shortly, our December issue will be a a special issue on the Image Gently campaign, an initiative of the Alliance for Radiation Safety in Pediatric Imaging,with an interview hosted by Sylvain Costes.

This month’s edition of the Radiation Research Podcast features Vered Anzenberg’s News minute, with some highlights from a College of Medicine study of viral infection of breast cancer cells at various stages of development, and an interview with Erik Young, hosted by Marjan Boerma.

Columbia University researchers Erik Young and Lubomir Smilenov (pictured below) are co-authors of the paper entitled Impedance-Based Surveillance of Transient Permeability Changes in Coronary Endothelial Monolayers after Exposure to Ionizing Radiation, appearing in the October issue of Radiation Research.

Welcome to the September 2011 Radiation Research podcast. This month, Vered’s news minute highlights a new international video contest launched by…YouTube. Following,Massimo interviews Mark Hill, from Oxford University and last author of the paper entitled The Role of Radiation Quality in the Stimulation of Intercellular Induction of Apoptosis in Transformed Cells at Very Low Doses.

Authors of this month’s featured paper include Dr Abdelrazek Abdelrazzak, Dr Mark Hill, and Dr Peter O’ Neill.

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The interview of the month is with Marc Mendonca from Department of Radiation Oncology, Indiana University School of Medicine. He is the author of the paper Differential Mechanisms of X-Ray-Induced Cell Death in Human Endothelial Progenitor Cells Isolated from Cord Blood and Adults.

The interview of the month is with Camille Metz-Flamant from the French Institute for Radiological Protection and Nuclear Safety (IRSN), the first author of the paper entitled: Solid Cancer Mortality Associated with Chronic External Radiation Exposure at the French Atomic Energy Commission and Nuclear Fuel Company.

Vered’s News Minute discusses how inverting a standard experiment sometimes produces different results, particularly with nanoparticles… Happy listening!

The interview of the month is with Dr. Joel Greenberger, of University of Pittsburgh Cancer Institute, last author of the paper entitled: Antioxidant-Chemoprevention Diet Ameliorates Late Effects of Total-Body Irradiation and Supplements Radioprotection by MnSOD-Plasmid Liposome Administration.

This month’s podcast features an interview with Vincent Caiozzo and Charles Limoli from the University of California at Irvine, who have released a study on the effect of ionizing radiation on muscle cells and how nitric oxyde mediates this response. Their manuscript is entitled:Satellite Cells Say NO to Radiation.

The interview of the month is with Manuela Buonanno and Edouard Azzam, of New Jersey Medical School, first and last authors of a paper entitled Long-Term Consequences of Radiation-Induced Bystander Effects Depend on Radiation Quality and Dose and Correlate with Oxidative Stress.

This month’s podcast features an interview with Sunirmal Paul and Sally Amundson from Columbia University, New York, who are first and last author of a paper entitled: Prediction of In Vivo Radiation Dose Status in Radiotherapy Patients using Ex Vivo and In Vivo Gene Expression Signatures.
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This month’s podcast includes an interview with Sountharia Rajendran from the University of Michigan and JamesTucker from Wayne State University, who discuss their article:

The Role of Mitochondria in the Radiation-Induced Bystander Effect in Human Lymphoblastoid Cells

Vered’s News Minute discusses the process of scientific publication … Happy listening!

This month’s podcast includes an interview with Drs. Peter Grabham and Charles Geard fromColumbia University, who discuss their article: "Effects of Ionizing Radiation on Three-Dimensional Human Vessel Models: Differential Effects Accordingto Radiation Quality and Cellular Development”.

Vered’s News Minute is about a group of British schoolchildren who may be the youngest scientists ever to have their work published in a peer-reviewed journal.

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This podcast number is published in memoriam of Elaine Ron, who passed away on November 20, 2010. A special issue of Radiation Research was published this month with a selection of papers presented at the Conference "Late Health Effects of Ionizing Radiation: Bridging the Experimental and Epidemiologic Divide” that was held in Washington DC, in May 2009. Massimo interviews Peter Jacob, co-author with Elaine Ron of the paper that introduces the special issue.

Vered’s News Minute focuses on the most affordable particle accelerator: a strip of Scotch tape!

Welcome to the November 2010 issue of the Radiation Research podcast, featuring the interview with Ingeborg Tinhofer, the final author of the paper entitled Pifithrin-α as a Potential Cytoprotective Agent in Radiotherapy: Protection of Normal Tissue without Decreasing Therapeutic Efficacy in Glioma Cells.

Inge Tinhofer’s research team: Inge Tinhofer (third from the left), first author Brigitte Sinn (third from the right)

Sylvain Costes interviews Drs. John-Aryankalayil and Palayoor, scientists from the Coleman Laboratory at the NCI, Radiation Oncology Branch, Bethesda, USA. They discuss how gene expression profiles of two different prostate carcinoma cells reveal distinct responses between acute and fractionated radiation exposures. The abstract of the manuscript can be found here.

Sylvain Costes interviews Drs. Luca Mariotti and Andrea Ottolenghi, from the department of nuclear physics and theory in Pavia, Italy. The discussion is centered on a mathematical framework for understanding the impact of intercellular signaling on bystander phenomena observed after exposure to ionizing radiation. The abstract of the paper can be found here.

Authors of the featured paper: Edouard Azzam (left photo), Massimo Pinto and Roger Howell (right photo).

The interview of the month is curated by Marjan Boerma, who spoke to the authors of the paper entitled Investigation of Adaptive Responses in Bystander Cells in 3D Cultures Containing Tritium-Labeled and Unlabeled Normal Human Fibroblasts.

Drs. Debabrata Saha and Timothy D. Solberg from the Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas, are interviewed about their work.Our conversation is based on their article published in the July issue of Radiation Research: An Orthotopic Lung Tumor Model for Image-Guided Microirradiation in Rats

Drs. Devika B. Chithrani and David A. Jaffray from the Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada are interviewed about their work on novel approaches to radiosensitize cells.Our conversation is based on their article published in the June issue of Radiation Research: Gold Nanoparticles as Radiation Sensitizers in Cancer Therapy.

This months "News Minute with Vered” focuses on the odd story of the classification of the tomato as a vegetable.

Drs. Rohan Kulkarni and James Tucker are interviewed about their work on the response of mitochondrial mutant cells to genotoxic stresses such as ionizing radiation.Our conversation is based on their article published in the May issue of Radiation Research: Mitochondrial Gene Expression Changes in Normal and Mitochondrial Mutant Cells after Exposure to Ionizing Radiation.

This months "News Minute with Vered” covers up the story of the origin of the Lab coat, and its colour.

Dr. Xiao Wen Mao was interviewed about their work on the response of micro vessels in the hippocampus after high-LET radiation.The conversation is based on their article published in the April issue of Radiation Research: High-LET radiation-induced response of microvessels in the Hippocampus.

Authors of this month’s article:
Xiao Wen Mao (pictured in the center), Cecile J. Favre (right), John R. Fike, Lucie Kubinova, Ella Anderson, Mary Campbell-Beachler, Tamako Jones, Anna Smith, Steven Rightnar, and Gregory A. Nelson (pictured left)

We begin our podcast with a "News Minute with Vered”, who discusses the nominees for the Nobel Peace prize for 2010. Will we win this year? This month our interview is with Karl Brehwens and Andrzej Wojcik and discusses their article: Cytogenetic Damage in Cells Exposed to Ionizing Radiation under Conditions of a Changing Dose Rate. The authors used a setup in which cells, kept at a constant temperature, moved to and from an X-ray source to expose them to a changing dose rate, as shown in their video: Experimental setup of Karl Brehwens and colleagues.

Late Residual γ-H2AX Foci In Murine Skin are Dose Responsive and Predict Radiosensitivity In Vivo

Any comments as to the content of the interview are encouraged.

Our interview of the month is to Disha Dayal (pictured on the left) and Douglas Spitz (pictured on the right), to discuss about their recent work appeared in the December issue of the Journal, of which they are first and last authors, respectively. The paper is entitled Mitochondrial Complex II Dysfunction Can Contribute Significantly to Genomic Instability after Exposure to Ionizing Radiation.

Any comments to the content of the interview are encouraged.

Happy festive season to all our listeners!