The radiation-induced bystander effect: evidence and significance

2004 ◽  
Vol 23 (2) ◽  
pp. 61-65 ◽  
Author(s):  
Edouard I Azzam ◽  
John B Little
Keyword(s):  
Ionizing Radiation ◽  
Radiation Exposure ◽  
Low Dose ◽  
Bystander Effect ◽  
Current Knowledge ◽  
Biological Effects ◽  
High Dose ◽  
Adaptive Responses ◽  
Radiation Induced

A multitude of biological effects observed over the past two decades in various in vivo and in vitro cell culture experiments have indicated that low dose/low fluence ionizing radiation has significantly different biological responses than high dose radiation. Exposure of cell populations to very low fluences of particles or incorporated radionuclides results in significant biological effects occurring in both the irradiated and nonirradiated cells in the population. Cells recipient of growth medium from irradiated cultures can also respond to the radiation exposure. This phenomenon, termed the ‘bystander response’, has been postulated to impact both the estimation of risks of exposure to ionizing radiation and radiotherapy. Amplification of radiation-induced cyto-toxic and genotoxic effects by the bystander effect is in contrast to the observations of adaptive responses, which are generally induced following exposure to low dose, low linear energy transfer radiation and which tend to attenuate radiation-induced damage. In this article, the evidence for existence of radiation-induced bystander effects and our current knowledge of the biochemical and molecular events involved in mediating these effects are described. Potential similarities between factors that mediate the radiation-induced bystander and adaptive responses are highlighted.

scholarly journals Low dose ionizing radiation induced acoustic neuroma: A putative link?

2012 ◽  
Vol 01 (01) ◽  
pp. 078-079
Author(s):  
Sachin Borkar ◽  
Deepak Agrawal
Keyword(s):  
Ionizing Radiation ◽  
Brain Tumors ◽  
Acoustic Neuroma ◽  
Cumulative Dose ◽  
Low Dose ◽  
High Dose ◽  
Atomic Reactor ◽  
Radiation Induced

Abstract Although exposure to high dose ionizing radiation (following therapeutic radiotherapy) has been incriminated in the pathogenesis of many brain tumors, exposure to chronic low dose ionizing radiation has not yet been shown to be associated with tumorigenesis. The authors report a case of a 50-year-old atomic reactor scientist who received a cumulative dose of 78.9 mSv over a 10-year period and was detected to have an acoustic neuroma another 15 years later. Although there is no proof that exposure to ionizing radiation was the cause for the development of the acoustic neuroma, this case highlights the need for extended follow-up periods following exposure to low dose ionizing radiation.

Low-Dose Ionizing Radiation from Medical Imaging

2016 ◽  
Author(s):  
Christoph I. Lee
Keyword(s):  
Medical Imaging ◽  
Ionizing Radiation ◽  
Radiation Exposure ◽  
Low Dose ◽  
Additional Information ◽  
Radiation Induced Cancer ◽  
Radiation Induced ◽  
Effective Doses ◽  
Study Methodology ◽  
Ionizing Radiation Exposure

This chapter, found in the radiation exposure from medical imaging section of the book, provides a succinct synopsis of a key study examining low-dose ionizing radiation exposure and radiation-induced cancer risks. This summary outlines the study methodology and design, major results, limitations and criticisms, related studies and additional information, and clinical implications. The study reported that a substantial proportion of the nonelderly US population is exposed to medium to very high annual effective doses from medical imaging procedures. Strategies ensuring the appropriate use of medical imaging associated with ionizing radiation should be developed and adopted widely. In addition to outlining the most salient features of the study, a clinical vignette is included in order to provide relevant clinical context.

scholarly journals MicroRNA Expression Profiling Altered by Variant Dosage of Radiation Exposure

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Kuei-Fang Lee ◽  
Yi-Cheng Chen ◽  
Paul Wei-Che Hsu ◽  
Ingrid Y. Liu ◽  
Lawrence Shih-Hsin Wu
Keyword(s):  
Radiation Exposure ◽  
Expression Profiling ◽  
Bystander Effect ◽  
Mononuclear Cells ◽  
Radiation Treatment ◽  
Human Peripheral Blood ◽  
Biological Effects ◽  
Mirna Gene ◽  
Knowledge Bases ◽  
Radiation Induced

Various biological effects are associated with radiation exposure. Irradiated cells may elevate the risk for genetic instability, mutation, and cancer under low levels of radiation exposure, in addition to being able to extend the postradiation side effects in normal tissues. Radiation-induced bystander effect (RIBE) is the focus of rigorous research as it may promote the development of cancer even at low radiation doses. Alterations in the DNA sequence could not explain these biological effects of radiation and it is thought that epigenetics factors may be involved. Indeed, some microRNAs (or miRNAs) have been found to correlate radiation-induced damages and may be potential biomarkers for the various biological effects caused by different levels of radiation exposure. However, the regulatory role that miRNA plays in this aspect remains elusive. In this study, we profiled the expression changes in miRNA under fractionated radiation exposure in human peripheral blood mononuclear cells. By utilizing publicly available microRNA knowledge bases and performing cross validations with our previous gene expression profiling under the same radiation condition, we identified various miRNA-gene interactions specific to different doses of radiation treatment, providing new insights for the molecular underpinnings of radiation injury.

scholarly journals Newly Developed Recombinant Antithrombin Protects the Endothelial Glycocalyx in an Endotoxin-Induced Rat Model of Sepsis

2020 ◽  
Vol 22 (1) ◽  
pp. 176
Author(s):  
Toshiaki Iba ◽  
Jerrold H. Levy ◽  
Koichiro Aihara ◽  
Katsuhiko Kadota ◽  
Hiroshi Tanaka ◽  
...  
Keyword(s):  
Dose Group ◽  
Low Dose ◽  
Leukocyte Adhesion ◽  
Endothelial Glycocalyx ◽  
High Dose Group ◽  
Control Group ◽  
High Dose ◽  
Protective Effects ◽  
Circulating Levels

(1) Background: The endothelial glycocalyx is a primary target during the early phase of sepsis. We previously reported a newly developed recombinant non-fucosylated antithrombin has protective effects in vitro. We further evaluated the effects of this recombinant antithrombin on the glycocalyx damage in an animal model of sepsis. (2) Methods: Following endotoxin injection, in Wistar rats, circulating levels of hyaluronan, syndecan-1 and other biomarkers were evaluated in low-dose or high-dose recombinant antithrombin-treated animals and a control group (n = 7 per group). Leukocyte adhesion and blood flow were evaluated with intravital microscopy. The glycocalyx was also examined using side-stream dark-field imaging. (3) Results: The activation of coagulation was inhibited by recombinant antithrombin, leukocyte adhesion was significantly decreased, and flow was better maintained in the high-dose group (both p < 0.05). Circulating levels of syndecan-1 (p < 0.01, high-dose group) and hyaluronan (p < 0.05, low-dose group; p < 0.01, high-dose group) were significantly reduced by recombinant antithrombin treatment. Increases in lactate and decreases in albumin levels were significantly attenuated in the high-dose group (p < 0.05, respectively). The glycocalyx thickness was reduced over time in control animals, but the derangement was attenuated and microvascular perfusion was better maintained in the high-dose group recombinant antithrombin group (p < 0.05). (4) Conclusions: Recombinant antithrombin maintained vascular integrity and the microcirculation by preserving the glycocalyx in this sepsis model, effects that were more prominent with high-dose therapy.

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