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X-rating, X-Rays By Mrs Vera West

     I have always felt uneasy about X-rays, I mean, it is quite unnatural to be able to see inside one’s body. Surely if God wanted this, He would have made us with zippers, or transparent! 
And, now that we, well, maybe not me, but scientists, know about DNA and mutations, there are other questions to ask:

“X-rays have been a staple of modern medicine for a long time, and any doctor or radiologist is quick to tell their patients that there are absolutely no risks or harmful side effects associated with the radiation necessary to perform an X-ray. Now, researchers from Erasmus University Medical Center and Oncode Institute in the Netherlands have discovered that low doses of radiation, long believed to be safe, did in fact create breaks in lab grown human cells that allowed additional DNA to enter the chromosome. In more simplistic terms, the radiation caused mutations on the cellular level. To be clear, these findings do not mean that going to have an X-ray is going to harm you, and extensive further research is necessary involving actual living animals, and eventually humans, before any real conclusions can be drawn. Still, the results of this study at the very least are concerning, and seem to indicate that there are still some aspects of how radiation interacts with our bodies, on a cellular level, that science has yet to fully understand.

High doses of radiation are almost certain to cause mutations in the exposed, often leading to cancer, or even worse symptoms in extreme circumstances. This happens because ionizing radiation creates double-strand breaks in cells that allow excess DNA to enter. These extra pieces of DNA usually make their way to the nucleus, leading to cellular mutations. For this study, researchers wanted to see if low, generally considered safe, doses of radiation would have any negative side effects on lab-grown human and mouse cells. As far as X-rays go, the radiation doses used in this experiment were comparable to the “upper range of common diagnostic procedures.” After exposing the cells to the radiation, it was observed that mutations, via inserted DNA, had indeed taken root in the cells. Surprisingly, these low doses of radiation actually caused mutations in the cells “more efficiently” than higher doses had in previous studies. Again, while these results certainly require additional investigation, the study’s authors make it very clear that it is far too early to come to any conclusions. Extensive additional research is necessary to determine if low-dose radiation has the same effect on patients when used for medical imaging procedures. If that were to be confirmed, researchers say that doctors would have to consider each individual patient’s personal level of extraneous DNA when deciding if a radiation-based imaging technique is the right route to take. “Most molecular radiobiological research is focused on high doses of ionizing radiation relevant to cancer treatment, while effects of physiologically relevant doses of radiation on the cell are notoriously difficult to study at the molecular level,” explains study author Roland Kanaar in a release. “Our discovery that mutagenic insertion of foreign DNA into cell’s genome is remarkably responsive to doses encountered during diagnostic, rather than therapeutic, procedures provides a new simple and sensitive tool to study their consequences and revealed surprising molecular genetic details of how cells cope with natural amounts of DNA damage.”

     Here is the study, published in PLOS Genetics:

“Extrachromosomal DNA can integrate into the genome with no sequence specificity producing an insertional mutation. This process, which is referred to as random integration (RI), requires a double stranded break (DSB) in the genome. Inducing DSBs by various means, including ionizing radiation, increases the frequency of integration. Here we report that non-lethal physiologically relevant doses of ionizing radiation (10–100 mGy), within the range produced by medical imaging equipment, stimulate RI of transfected and viral episomal DNA in human and mouse cells with an extremely high efficiency. Genetic analysis of the stimulated RI (S-RI) revealed that it is distinct from the background RI, requires histone H2AX S139 phosphorylation (?H2AX) and is not reduced by DNA polymerase ? (Polq) inactivation. S-RI efficiency was unaffected by the main DSB repair pathway (homologous recombination and non-homologous end joining) disruptions, but double deficiency in MDC1 and 53BP1 phenocopies ?H2AX inactivation. The robust responsiveness of S-RI to physiological amounts of DSBs can be exploited for extremely sensitive, macroscopic and direct detection of DSB-induced mutations, and warrants further exploration in vivo to determine if the phenomenon has implications for radiation risk assessment.”

     Ok, I got some of that. What now? As with everything one needs to exercise caution and make up one’s own mind. It would be difficult to go without some x-rays, especially dental, so clean your teeth, if you are lucky enough to have them!



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Sunday, 31 May 2020
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