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May 2013: Dr. Erik Young interviews Dr. Charles Limoli on his paper ''Mitochondrial-targeted human catalase affords neuroprotection from proton irradiation.''

Posted By Administration, Tuesday, September 10, 2013

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April 2013: Massimo Pinto interviews Brad Loucas on the paper written with Michael Cornforth & entitled: the LET dependence of unrepaired chromosome damage in human cells: a break too far?

Posted By Administrator, Tuesday, September 10, 2013



Cycle Structure and its Relation to the Break Too Far Hypothesis

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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March 2013: Comparing the Effect of Protons to X-rays/Gamma-rays

Posted By Administration, Friday, May 10, 2013

Sylvain Costes speaks with Rainer Sachs, Professor Emeritus of Mathematics and of Physics from UC Berkeley and Swati Girdhani, assistant professor at GeneSys Research Institute (GRI) / Tufts University School of Medicine  (http://cancer-systems-biology.org/) for their recent review in the March issue of Radiation Research, entitled " Biological effects of proton radiation: what we know and don't know ". This is a special Videocast interview done in the Faculty Club of the University of California at Berkeley.

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Interview with Drs. Grdina and Murley

Posted By Administration, Monday, February 18, 2013
Updated: Tuesday, June 11, 2013

This month Erik Young interviews Drs. Grdina and Murley on their paper entitled "A manganese superoxide dismutase (SOD2)-mediated adaptive response". The podcast also features a News Minute from a new podcast volunteer, Olivia Kelada. Welcome Olivia!!!

CLICK HERE TO LISTEN TO PODCAST

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Interview with Dr. Norman Coleman

Posted By Administration, Thursday, January 31, 2013
Updated: Friday, May 10, 2013

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Interview with Ross Berbeco

Posted By Administration, Wednesday, January 30, 2013
Updated: Monday, April 22, 2013

 

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.

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Interview with Michael Scholtz

Posted By Administration, Tuesday, January 29, 2013
Updated: Monday, April 22, 2013

 

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.

Tags:  DNA damage  DNA repair  Modeling 

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Interview with Richard Britten

Posted By Administration, Thursday, December 06, 2012
Updated: Monday, April 22, 2013

 

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.

Tags:  Low dose 

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Interview with John Lazo

Posted By Administration, Friday, November 23, 2012
Updated: Monday, April 22, 2013

 

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.

Tags:  countermeasures 

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Interview with Eric Grant from RERF

Posted By Administration, Tuesday, November 20, 2012
Updated: Monday, April 22, 2013

 

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.

Tags:  cancer risk 

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