This box was the same as that used to carry the flasks to and from the laboratory and the radiation center (a 2 minute walk). If no bystander effect is induced in these cell lines, then it may be likely that neutrons do not have any ability to induce a bystander effect. The increases for both micronuclei and bridges with dose were significant with and without considering the 4 Gy data point (p<0.0001). Following irradiation, the cells were left undisturbed until media transfer, which was performed four hours after irradiation as previously described [17]. Recently, some laboratories have suggested that the presence of serotonin in the serum is one of the key factors involved in the bystander effect [49]â[51], however this finding has been disputed [52]. Another, more severe hazard of neutron radiation, is neutron activation, the ability of neutron radiation to induce radioactivity in most substances it encounters, including bodily tissues. Yes 1s, pp. However, other studies have reported contrasting results. Two flasks per cell line were then shipped overnight to the University of Washington Medical Center (UWMC), Seattle. Similar to X-rays, gamma rays can get past even some of the densest materials in use, making them both a great benefit and a hazard. However, few studies have been performed to investigate bystander effects arising from neutron irradiation. No, Is the Subject Area "Radiation therapy" applicable to this article? Hence, reevaluation of radiation protection standards may be required. For each experiment, the independent variables considered were cell line, dose, and the interaction between cell line and dose. [59] found that transplantation of a mixture of neutron irradiated and unirradiated bone marrow cells into mice induced instability in the descendants of unirradiated cells as confirmed by measuring chromosomal aberrations, indicating that neutrons induce a bystander effect. Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads in Europe. They reported an increase in the frequency of mutations in the hypoxanthine-guanine phosphoribosyltransferase locus in cells located near the irradiated cells. For the gamma radiation experiments, flasks were transported to and from the laboratory and the radiation center, a 5-minute car ride, in an insulated container as described above. The cell cultures were then incubated at 37°C for 28 hours. [57] studied a neutron-induced bystander effect in boron neutron capture therapy with a cell survival assay as well as cloning and sequencing methods. Ionizing radiation is a form of energy that acts by removing electrons from atoms and molecules of materials that include air, water, and living tissue. Neutron radiation — consisting of free neutrons which are released during fission but not usually through radioactive decay. For GM15510 cells, although the micronuclei frequencies show substantial variation, there clearly is not any consistent evidence of a bystander effect. For each treatment (i.e., cell line and dose group) the left-hand bar in each pair is replicate 1 and the right-hand bar is replicate 2. Depending upon the cell and tissue type, bystander signals can be transmitted either through the culture medium [17] or by cell-to-cell contact including gap junctional communication [37]. As a positive control for the bystander effect, cells were exposed to 0 (sham), 0.5, 1, 2, 3 and 4 Gy cobalt-60 gamma rays. In contrast, there was no statistically significant bystander component for neutrons (data not shown). The principal kinds of ionizing radiation are: Both pre- and post-radiation treatment with DMSO is known to suppress DNA damage in irradiated cells [66]. For more information about PLOS Subject Areas, click To determine whether these low doses of contaminating photons can induce a bystander effect, cells were irradiated with cobalt-60 at doses equivalent to the percent contamination for each neutron dose. They measured apoptosis and cell survival in zebrafish that received bystander signals from fish that were directly irradiated with neutrons. As expected, the media-only control and the 0 Gy control were not statistically different (p>0.05). For the endpoints of micronuclei and nucleoplasmic bridges, we found no evidence to indicate that neutrons induce a bystander effect in normal human lymphoblastoid cells. Understanding the biological effects of neutrons may also enable more refined evaluations of the standards for radiation protection and safety. Kinashi et al. These may include diarrhea, headache, hair loss, skin burns and poor healing, according to the Mayo Clinic 1.cause: These may include diarrhea Buds were counted only if the stalk was thinner than the widest part of the bud. The Nuclear Division Index (NDI) for each dose and treatment was determined by evaluating at least 200 cells and determined according to the following formula: where M1-M4 represent the number of cells with one to four nuclei, respectively, and N is the total number of cells scored [75]. Full Record; Other Related Research; Abstract. A bystander effect following neutron exposure has been observed in Chinese hamster ovary cells [57], but no effect was seen in zebrafish irradiated in vivo [56]. [56] have suggested that neutrons might suppress gamma ray-induced bystander signaling. Cell culture was performed using the standardized protocol provided by Coriell. Cells that do not absorb radiation directly may nevertheless be damaged or altered in ways that do not become apparent for many cell generations. Department of Radiation Oncology, Wayne State University, Detroit, Michigan, United States of America, * E-mail: jtucker@biology.biosci.wayne.edu. The non-irradiated cells in the conditioned media were then transferred to new T-25 culture flasks and immediately after media transfer 6 µg/ml (final concentration) of Cytochalasin B was added to each culture to block cytokinesis. Yes Biomedical/nuclear engineer ely5: While gamma or Xray radiation is just photons that have to rely on funny electric and quantum effects to manipulate the "macro" word, neutrons are large enough to act like actual projectiles to molecules of smaller atoms (e.g. For cells irradiated with high doses of photons, a considerable amount of damage was attributed to the bystander component. The cells were then harvested as described below. Unlike low-LET radiation, for high-LET radiation there is also a reduction in the differential radiosensitivity of cells related to their position in cell cycle [60]. As expected, GM15510 and GM15036 cells cultured in ICCM obtained from cells exposed to high doses of cobalt-60 gamma rays showed a 2 to 3 fold increase in micronuclei frequencies compared to sham treated controls, clearly indicating induction of a bystander effect (Figure 5a). We also included a media-only control containing fresh media without cells, which was irradiated at the highest dose, i.e. Furthermore, due to the lower levels of oxidative damage and free radical production by neutrons compared to photons [60], some of the critical bystander signaling pathways may not be activated. 0.2 Gy. Cells that were directly irradiated as well as those treated with conditioned media were centrifuged onto ethanol-cleaned microscope slides for 4 minutes at 93 x g using a cytocentrifuge (Statspin, Westwood, MA). In addition, late effects such as chromosomal instability may increase susceptibility to cancer [21]. Gamma radiation is the most penetrative type of energy currently known. Yes Depending on the energy these particles constitutes, radiation forms two categories, ionizing and non-ionizing radiation. The harmful effects of radiation on humans range from nausea and headache, which are triggered when the exposure is mild, to something as severe as genetic mutation and death. Nucleoplasmic bridges (Figure 5b) showed a weak bystander effect for GM15510 (pâ=â0.052), and for GM15036 the effect was highly significant (p<0.0001). We have used a novel neutron irradiator with an energy spectrum based on that 1-1.5 km from the epicenter of the Hiroshima blast to begin examining the effect of neutrons on global gene expression, and the impact this may have on the development of gene expression signatures for radiation biodosimetry. PLoS ONE 9(6): Copyright: © 2014 Seth et al. Skip to primary navigation Our RBE values are within the range of what others have reported. High levels of neutron irradiation occur in patients receiving neutron therapy, while low levels of neutron exposure occur in patients treated with high energy photons and protons. Following exposure the flasks were returned immediately to the laboratory and incubated for 28 hours. Ionizing radiation can travel unseen and pass through these materials. Cells were then evaluated simultaneously for micronuclei, nucleoplasmic bridges and buds according to our ârelaxedâ criteria [76]. They are … Conceived and designed the experiments: IS JDT RDS MCJ. Beta particles(electrons) are much small… Conception of the neutron bomb is generally credited to Samuel T. Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958. As such, there is a sharper distinction, relative to thermal effects, between areas of high lethality and areas with minimal radiation doses. Ionizing vs. Nonionizing Radiation. For neutron irradiations, the cells in culture medium in T-25 flasks were irradiated at room temperature with doses 0 (sham), 0.5, 1, 1.5, 2, 3 and 4 Gy. This is also known as radiation poisoning. To assess the effects of direct radiation damage on these cells, Cytochalasin B (6 µg/ml final concentration; Sigma, St. Louis, MO) dissolved in DMSO (Fisher Scientific, Pittsburg, PA) was added four hours after irradiation to directly-irradiated cells to block cytokinesis. These results suggest that a neutron bystander effect may be comprised of gene mutations. Neutrons, depending on their energy, might be more effective in controlling certain tumor types where conventional photon therapy is ineffective [63] because the oxygen enhancement ratio, i.e. In an atomic explosion, the neutron radiation is particularly harmful. The effects of radiation on the human body Radioactive materials are hazardous. While many exist in nature, the majority are created in nuclear reactionsa. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0098947. A theoretical analysis of radiation sensitivity in cells following neutron irradiation (IAEA-SM-179/18) 151 H. P. Leenhouts, Κ . here. C. Medvedovsky and B. V. Worgul (1991) Neutron Effects on the Lens.Radiation Research: October 1991, Vol. However, if a very small bystander effect was in fact induced by neutrons, then it may have been obscured by the DMSO, whereas the bystander effect induced by high levels of photons was too large to be masked by DMSO. Such non-targeted effects may have serious implications for human health and may cause cancer. Some of the candidate intercellular signaling molecules that have been implicated in bystander effects are reactive oxygen species [20], [38], reactive nitrogen species [20], [38], nitric oxide [27], [38], cytokines such as TGFβ and interleukin 8 [39], and small molecules such as amino acids [37], [40], [41]. Citation: Seth I, Schwartz JL, Stewart RD, Emery R, Joiner MC, Tucker JD (2014) Neutron Exposures in Human Cells: Bystander Effect and Relative Biological Effectiveness. Here we used the cytokinesis-block micronucleus assay to address the question whether neutrons induce a bystander effect in normal human lymphoblastoid cell lines. For both cell lines and for both end-points, i.e. RBEs of 2.0±0.13 for micronuclei and 5.8±2.9 for nucleoplasmic bridges relative to cobalt-60 suggest that different kinds of genetic damage may be associated with different RBEs. https://doi.org/10.1371/journal.pone.0098947.g003. For the bystander effect an additional media-only control was included; these flasks contained fresh, complete, culture media without any cells and were irradiated at the highest dose, i.e. [72] used the cytokinesis-block micronucleus assay and a cell survival assay in a human colon carcinoma cell line and observed an RBE of 4.4 for neutrons in boron neutron capture therapy. RBEs for neutrons as low as 4 to as high as 63 have been reported after measuring life-shortening responses in mice [73], apoptosis [1] and induction of dicentrics [74] in human lymphocytes. This change in quality of a mixed-spectrum field is significant since the biological damages produced by high-LET and low-LET radiations are not equivalent. The transportation control involved flasks that were transported with the cells that were irradiated, but remained inside the insulated box; these control flasks were further insulated with bubble wrap to maintain their temperature close to 37°C. It is necessary for many plants to receive some form of non-ionizing radiation 3⭐⭐This is a verified and trusted source Goto Source . Other sources of low level neutron irradiation may include occupational exposure to workers at nuclear power plants and accelerator facilities, astronauts, airline crews and passengers on high altitude flights [3]â[14], as well as radiation incidents such as the Hiroshima-Nagasaki atomic bomb explosions and the tsunami-induced radiation leak at the Fukushima Daiichi site in Japan [15]. Exposure to very high levels of radiation, such as being close to an atomic blast, … How can ionizing radiation cause cancer? Yang et al. [71] reported RBEs of 2.35 and 2.42 for fast neutrons in immature rat hippocampal cells, as determined by two different cell viability assays. For the neutron radiation experiments, cells were grown at WSU up to a concentration of 1Ã106 cells/mL, then non-vented T-25 flasks were completely filled with media (60 ml) containing cells at this concentration. coli B/r and Bs-1 (IAEA-SM-179/11) 165 W. A. Cramp, P.E. Severe Radiation Sickness Larger acute doses of gamma radiation, or larger doses that accumulate over time, can lead to much more severe symptoms. When the biological responses for both radiation types are linearly related to dose, as seen here, the RBE is also the ratio of the biological effects at the same dose. The Radiation Answers Organization has a table describing the effects of radiation on humans at the Radiation Answers Organization website. [56] suggested that the gamma ray-induced bystander effect might have been suppressed by the neutron exposures. The results, shown in Figure 3, indicate that these low doses of photons did not produce a bystander effect. For both cell lines, direct irradiation with neutrons resulted in clear dose-responsive increases in the number of micronuclei (Figure 1a) and nucleoplasmic bridges (Figure 1b) per 1000 binucleated cells. Since neutrons are scattered and absorbed by air, neutron radiation effects drop off rapidly with distance in air. While much has been learned about x-ray and gamma-ray effects on cells and whole organisms, less is known about the biological effects of neutrons. This is due largely to the increased ionization that takes place near the track a particle of space radiation takes through a material. For more information about PLOS Subject Areas, click The media from the non-irradiated (bystander) cells was gently removed by aspiration and replaced with conditioned media. 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