Influence of the lead ions and low dose radiation on the catalase activity in the maize germinant

The impact of long-term low-dose radiation on human health has always been a concern. Long-term low-dose gamma radiation causes cells continuous injury and causes chromosomal mutations to greatly increase the chance of cancer. Because it is significant to identify biomarkers for long-term low-dose gamma radiation, we investigate the influence of low dose rate on the gene expressions in the AHH-1 lymphocytes cell line (AHH-1 cells) for long-term irradiation. Different dose rates (7, 14, 26, 34, and 43 μGy h-1) of irradiation from gamma radiation in uranium tailings powder were used to irradiate AHH-1 lymphocytes. We used flow cytometry to test the apoptosis of AHH-1 lymphocytes at different dose rates and irradiation times (7-84 d). It was found that 14 μGy h-1 is the most sensitive dose rate of AHH-1 lymphocyte irradiation. The 7-, 14-, and 21-d (2.4, 4.8, and 7.2 mGy) irradiation groups were sensitive, and the 84-d (28.8 mGy) irradiation group was insensitive to low dose gamma radiation. Microarray analysis was conducted on the significantly differentially expressed genes (p<0.05) in the 2.4, 4.8, 7.2, and 28.8 mGy irradiation groups. We found that TFRC1, SLC3A2, SLC39A8, FTH1, ACSL4, and GPX4 are significant genes with low-dose radiation and were constituents of the ferroptosis signaling pathway. In the range of 0-4.8 mGy radiation dose, the expressions of these genes were downregulated with increasing radiation dose, while in the range of 4.8-28.8 mGy, its expression increased with increasing radiation dose. RT-PCR and Western blot were used to detect the mRNA and protein expression of these genes. The results were consistent with those from microarray analysis. Our findings indicate that expression of the TFRC, SLC3A2, SLC39A, FTH1, ACSL4, and GPX4 genes is sensitive to low-dose radiation, and they are main members of the ferroptosis signaling pathway. Therefore, there is a very important connection between ferroptosis and low-dose radiation, which has become a hot topic in international research. These results can provide reference to the effect of ferroptosis on human health with low-dose radiation.

Study question How do immune cells in the mouse ovary react after low dose radiation? Summary answer Already shortly after low dose radiation, immune cells are activated in the mouse ovary, dropping to normal levels within short time. What is known already Gonadotoxic treatment in female cancer patients can lead to reversible or permanent fertility impairment. Maintaining gonadal function and preserving fertility after successful cancer treatment have become critical concerns for young fertile patients. Radiation is a cornerstone in cancer treatment. The risk of damage depends on the dose and the site of radiation. There are a few studies (A small number of studies exists) assessing the radiation-induced damage to primordial oocytes in animal models, and even fewer data on radiation-induced damage to the stroma and reaction of immune cells in the ovary Study design, size, duration In this mouse model, 60 6-weeks old female C57BL/6J mice were radiated locally (abdomen[VS1] ) with either 1 or 4.5 Gy. There control group was not radiated. After radiation, mice were sacrificed and ovaries, pelvic lymph nodes, and the spleen were than analyzed by Fluorescence acitvated cell sorting (FACS) analysis at the Department of Gynecological Endocrinology and Reproductive Medicine, Medical University Innsbruck, Innsbruck, Austria between January and December 2023. Participants/materials, setting, methods After radiation, mice were sacrificed after 6h, 36h, 2 weeks and 5 weeks. Ovaries, pelvic lymph nodes, and the spleen were then analyzed by FACS analysis: NK cells, macrophages, dendritic cells, CD4+ and CD8+ cells, t cells and b cells were counted. The number of each cell type was compared to that of non-radiated mice. Main results and the role of chance The ovaries are composed of 1-2% immune cells. The immune cell population of the ovaries showed the following composition: NK cells including NK and NKT cells (34%; NKT (10%), T-cells (21%), macrophages (14%), B-cells (11%), dendritic cells (8%). In the ovary, within 6h after radiation no differences in the analyzed immune cells compared to the control group were seen, after 36h a significant increase of NK cells, macrophages, dendritic cells occurred in both groups (1 and 4.5Gy). Significant changes of levels of B Cells, dendritic cells, NK cells, den CD4+ and CD8+ cells remained after 2 weeks post radiation (p = 0.002). Five weeks post radiation, macrophages remained significantly elevated both in the low and high dose radiation group whereas other immune cell groups decrease to normal levels comparable to the control group. Analysis of the spleen and lymph nodes showed similar results. Limitations, reasons for caution A possible limitation is the small sample size. Wider implications of the findings This is the first study to analyze analyzing immune cells as part of the ovarian damage following radiation. Already shortly after low dose radiation, immune cells are activated in the mouse ovary, in line with activation in the spleen and lymph nodes dropping to normal levels within short time. Trial registration number No

It is increasingly realized that human exposure either to an acute low dose or multiple chronic low doses of low LET radiation has the potential to cause different types of cancer. Therefore, the central theme of research for DOE and NASA is focused on understanding the molecular mechanisms and pathways responsible for the cellular response to low dose radiation which would not only improve the accuracy of estimating health risks but also help in the development of predictive assays for low dose radiation risks associated with tissue degeneration and cancer. The working hypothesis for this proposal is that the cellular mechanisms in terms of DNA damage signaling, repair and cell cycle checkpoint regulation are different for low and high doses of low LET radiation and that the mode of action of phosphatidylinositol-3 kinase like kinases (PIKK: ATM, ATR and DNA-PK) determines the dose dependent cellular responses. The hypothesis will be tested at two levels: (I) Evaluation of the role of ATM, ATR and DNA-PK in cellular response to low and high doses of low LET radiation in simple in vitro human cell systems and (II) Determination of radiation responses in complex cell microenvironments such as human EpiDerm tissue constructs. Cellular responses to low and high doses of low LET radiation will be assessed from the view points of DNA damage signaling, DNA double strand break repair and cell cycle checkpoint regulation by analyzing the activities (i.e. post-translational modifications and kinetics of protein-protein interactions) of the key target proteins for PI-3 kinase like kinases both at the intra-cellular and molecular levels. The proteins chosen for this proposal are placed under three categories: (I) sensors/initiators include ATM ser1981, ATR, 53BP1, gamma-H2AX, MDC1, MRE11, Rad50 and Nbs1; (II) signal transducers include Chk1, Chk2, FANCD2 and SMC1; and (III) effectors include p53, CDC25A and CDC25C. The primary goal of this proposal is to elucidate the differences in cellular defense mechanisms between low and high doses of low LET radiation and to define the radiation doses where the cellular DNA damage signaling and repair mechanisms tend to shift. This information is critically important to address and advance some of the low dose research program objectives of DOE. The results of this proposed study will lead to a better understanding of the mechanisms for the cellular responses to low and high doses of low LET radiation. Further, systematic analysis of the role of PIKK signaling pathways as a function of radiation dose in tissue microenvironment will provide useful mechanistic information for improving the accuracy of radiation risk assessment for low doses. Knowledge of radiation responses in tissue microenvironment is important for the accurate prediction of ionizing radiation risks associated with cancer and tissue degeneration in humans.

FINAL TECHNICAL REPORT Supported by the Low Dose Radiation Research Program, Office of Science U.S. Department of Energy Grant No. DE-FG02-07ER64345 Project ID: 0012965 Award Register#: ER64345 Project Manager: Noelle F. Metting, Sc.D. Phone: 301-903-8309 Division SC-23.2 noelle.metting@science.doe.gov Submitted March 2012 To: https://www.osti.gov/elink/241.3.jsp Title: Th Cell Gene Expression and Function in Response to Low Dose and Acute Radiation PI: Daila S. Gridley, Ph.D. Human low dose radiation data have been derived primarily from studies of space and airline flight personnel, nuclear plant workers and others exposed occupationally, as well as victims in the vicinity of atomic bomb explosions. The findings remain inconclusive due to population inconsistencies and complex interactions among total dose, dose rate, radiation quality and age at exposure. Thus, safe limits for low dose occupational irradiation are currently based on data obtained with doses far exceeding the levels expected for the general population and health risks have been largely extrapolated using the linear-nonthreshold dose-response model. The overall working hypothesis of the present study is that priming with low dose, low-linear energy transfer (LET) radiation can ameliorate the response to acute high-dose radiation exposure. We also propose that the efficacy of low-dose induced protection will be dependent upon the form and regimen of the high-dose exposure: photons versus protons versus simulated solar particle event protons (sSPE). The emphasis has been on gene expression and function of CD4+ T helper (Th) lymphocytes harvested from spleens of whole-body irradiated C57BL/6 mice, a strain that provides the genetic background for many genetically engineered strains. Evaluations of the responses of other selected cells, tissues such as skin, and organs such as lung, liver and brain were also initiated (partially funded by other sources). The long-term goal is to provide information that will be useful in estimating human health risks due to radiation that may occur during exposures in the work environment, nuclear/radiological catastrophes, as well as radiotherapy. Several papers have been published, accepted for publication or are in preparation. A number of poster and oral presentations have been made at scientific conferences and workshops. Archived tissues of various types will continue to be evaluated via funding from other sources (the DoE Low Dose Radiation Research Program, Office of Science and this specific grant will be appropriately included in the Acknowledgements of all subsequent publications/presentations). A post-doc and several students have participated in this study. More detailed description of the accomplishments is described in attached file.

Research reports using cells from bacteria, yeast, alga, nematodes, fish, plants, insects, amphibians, birds and mammals, including wild deer, rodents or humans show non-linear radio-adaptive processes in response to low doses of low LET radiation. Low doses increased cellular DNA double-strand break repair capacity, reduced the risk of cell death, reduced radiation or chemically-induced chromosomal aberrations and mutations, and reduced spontaneous or radiation-induced malignant transformation in vitro. In animals, a single low, whole body dose of low LET radiation, increased cancer latency and restored a portion of the life that would have been lost due to either spontaneous or radiation-induced cancer in the absence of the low dose. In genetically normal fetal mice, a prior low dose protected against radiation-induced birth defects. In genetically normal adult-male mice, a low dose prior to a high dose protected the offspring of the mice from heritable mutations produced by the large dose. The results show that low doses of low-LET radiation induce protective effects and that these induced responses have been tightly conserved throughout evolution, suggesting that they are basic responses critical to life. The results also argue strongly that the assumption of a linear increase in risk with increasing dose in humans is unlikely to be correct, and that low doses actually reduce risk.

Ionizing radiation is known to cause cell apoptosis at high dose range, but little is known about the cellular response to low dose radiation. In this study, we found that conditioned medium harvested from WI-38 lung fibroblasts and H1299 lung adenocarcinoma cells exposed to 0.1Gy to 1Gy could enhance the migration and invasion of unirradiated H1299 cells in both 2D and 3D culturing circumstances. Low dose radiation did not induce apoptosis, but induced senescence in irradiated cells. We next examined the expression of immediately early genes including c-Myc and K-Ras. Although both genes could be up-regulated by low dose radiation, induction of c-Myc was more specific to low dose range (0.5Gy) at transcriptional and translational levels. Knockdown of c-Myc by shRNA could repress the senescence induced by low dose radiation. The conditioned medium of irradiated cells induced migration of unirradiated cells was also repressed by knockdown of c-Myc. The c-Myc inhibitor 10058-F4 could suppress low dose radiation induced cell senescence, and the conditioned medium harvested from irradiated cells pretreated with 10058-F4 also lost the ability to enhance the migration of unirradiated cells. The cytokine array analysis revealed that immunosuppressive monocyte chemoattractant protein-1 increased by low dose radiation could be repressed by 10058-F4. We also showed that 10058-F4 could suppress low dose radiation induced tumor progression in a xenograft tumor model. Taken together, current data suggest that -Myc is involved in low dose radiation induced cell senescence and potent bystander effect to increase the motility of unirradiated cells.

Objective To detect the effect on the growth of human glioma cell U251 induced by low dose irradiation and low dose irradiation combined with large dose irradiation.Methods Human glioma cell line U251 and nude mice carried with human glioma were used.The tumor cells and the mice were treated with low dose,high dose,and low dose combined hish dose radiation.Cells growth curve.MTT and flow cytometry were used to detect the proliferation,cell cycle and apoptosis of the cells;and the tumor inhibition rate was used to assess the growth of tumor in vivo.Results After low dose irradiation.there was no difference between experimental group and control group in cell count.MTT and flow cytometry.Single high dose group and low dose combined high dose group beth show significanly the suppressing effect on tumor cells,the apoptosis increased and there was cell cycle blocked in C2 period,but there was no difference between two groups.In vivo apparent anti-tumor effect in high dose radiation group and the combining group was observed,and that was more significant in the combining group;the prior low dose radiation alleviated the injury of hematological system. There was no difference between single low dose radiation group and control.Conclusions There is no significant effect on human glioma cell induced by low dose radiation, and low dose radiation could not induce adaptive response.But in vivo experience.low dose radiation could enhance the anti-tumor effect of high dose radiation and alleviated the injury of hematological system. Key words: Low dose radiation; Human glioma cell; Nude mice cancer model; Anti-tumor effect

Is low dose radiation therapy a potential treatment for COVID-19 pneumonia?

: Hormesis describes a phenomenon where low doses of toxic substances or radiation stimulate responses that might counteract the harmful effects of a subsequent high level of stress. We hypothesized that low doses of radiation received through mammography could be beneficial for patients. We therefore treated human breast epithelial cells with X-rays at low doses, high doses, or at low doses followed by high doses. We then scored cells for the effects of these various doses on the number of DNA damage 53BP1 foci and on the ability to trigger cell senescence. Based on the results we have obtained so far, there was no significant change in the amount of DNA damage foci generated nor in the induction of senescence when cells were pre-treated with low doses of ionizing radiation and subsequently challenged by a high dose of ionizing radiation. Moreover, there was no effect on chromatin modifications in mammary epithelial cells, whereas low doses of radiation appeared to have some effects in human fibroblasts. In conclusion, our data suggest that low doses of radiation are not protective, nor detrimental, in mammary epithelial cells, whereas in other cell types, such as fibroblasts, these low doses of radiation appear to be protective.

We examined whether low dose radiation (LDR) exposure (75 mGy) could increase the therapeutic efficacy of cyclophosphamide (CTX) by comparing the effects of tumor suppression, tumor cell apoptosis, cell cycle and proliferation of bone marrow in vivo. Kunming mice implanted with S(180) sarcoma cells were given 75 mGy whole body gamma-ray radiation exposure and CTX (300 mg/kg) by intraperitoneal injection 36 hours after LDR. Proliferation of bone marrow and tumor cells was analyzed by flow cytometry. Cytochrome c leakage from the tumor was measured by Western-blot. We discovered that tumor growth was significantly reduced in the group exposed to CTX add to LDR. The apoptosis of tumor cells increased significantly after LDR. The tumor cells were arrested in G(1) phase in the groups treated with CTX and CTX + LDR, but cell cycle was more significantly arrested in mice exposed to LDR followed by CTX than in mice exposed only to LDR or CTX chemotherapy. Concentration of bone marrow cells and proliferation index in CTX + LDR mice were higher than those in the untreated mice. LDR or CTX + LDR could induce greater cytochrome c levels and caspase-3 activity in tumors. These results suggest that low dose radiation can enhance the anti-tumor effect of the chemotherapy agent CTX markedly. Furthermore, LDR significantly protects hematopoetic function of the bone marrow, which is of practical significance on adjuvant chemotherapy.

Risk of cancer from diagnostic X-rays

Low dose radiation has been shown to be beneficial to living organisms using several biological systems, including immune and hematopoietic systems. Chronic low dose radiation was shown to stimulate immune systems, resulting in controlling the proliferation of cancer cells, maintain immune balance and induce hematopoietic hormesis. Since dendritic cells are differentiated from bone marrow cells and are key players in maintaining the balance between immune activation and tolerance, it may be important to further characterize whether low dose radiation can influence the capacity of bone marrow cells to differentiate into dendritic cells. We have shown that bone marrow cells from low dose-irradiated (γ-radiation, 0.2Gy, 15.44mGy/h) mice can differentiate into dendritic cells that have several different characteristics, such as expression of surface molecules, cytokine secretion and antigen uptake capacity, when compared to dentritic cells differentiated from the control bone marrow cells. These differences observed in the low dose radiation group can be beneficial to living organisms either by activation of immune responses to foreign antigens or tumors, or maintenance of self-tolerance. To the best of our knowledge, this is the first report showing that total-body low dose radiation can modulate the capacity of bone marrow cells to differentiate into dendritic cells.

Radiological protection is based on the assumption that any additional exposure to ionizing radiation produces an increased risk of stochastic adverse health effects. The ICRP has adopted linear no-threshold (LNT) dose-response relationships to derive health risks associated with low doses of radiation and this implies that the risks of cancer and hereditary effects are directly proportional to the dose received, no matter how small the dose. The LNT assumption has been criticised over the years both by those who consider that it underestimates the risk and by those who believe that it is overly conservative. A few years ago, most of the pressure on ICRP came from those who believed that the risks per unit dose adopted at low doses were too small, but in recent years the pressure has been coming from the opposite direction. Strictly speaking, ICRP feels that the most likely form of the dose-response relationship for low LET radiation is linear-quadratic (i.e. sub-linear at low doses), and for cancer they approximate this by two linear relations, that for the low dose region having a slope (risk per unit dose) half of that for the high dose region, represented by a DDREF of 2. Nevertheless, there are those (particularly in the US and France) who argue that there is no direct evidence for stochastic effects being produced by low doses of radiation, and that the appropriate dose-response relationship has a threshold dose below which no risk to health exists, or even that low doses of radiation are beneficial (`radiation hormesis').

Introduction: Tumor hypoxia is one of the major causes of high incidence of treatment failures to chemoradiation which is the standard of care in locally advanced cervical cancer. The necessity of newer treatment options that can circumvent hypoxia is highly relevant in this group. Use of low dose radiation to enhance the efficacy of cell cycle specific chemotherapy by mechanism of chemopotentiation is one of the elegant approaches reported in the literature. We have already published the feasibility, efficacy and tolerance of low dose radiation and chemotherapy in neoadjuvant setting in cervical cancer. In this report we evaluated the role of this novel treatment regimen in reducing the hypoxic tumor cell population in cervical cancer. Methods: Total 24 patients with stage IIB-IIIB squamous cell carcinoma cervix were treated with initial 2 cycles of paclitaxel and carboplatin and concurrent low dose radiotherapy prior to standard chemoradiation. Response was assessed clinically, radiologically (by MRI) and pathologically (four quadrant representative punch biopsy from the cervix) after 3 weeks of neoadjuvant treatment prior to chemoradiation. Immunohistochemistry of HIF-1a was done in the biopsy samples to determine the proportion, intensity and scoring of hypoxic cells. Results: The proportion of positivity of base line HIF-1α was 42% (10 out of 24 patients). Low, moderate and high expressions were seen in 8%, 17% and 17% respectively. We observed nuclear positivity in 20%, and fine granular perinuclear cytoplasmic positivity in 80% cases. We failed to observe any association between expressions of HIF 1α in relation to the distance from blood vessels in tumor cord. The average age of patients in hypoxia positive and negative groups were 51.7 vs 48.36 yrs (p &gt; 0.05). There was no difference of mean hemoglobin level (11.3 to 11.1, p &gt; 0.05.) or MRI based tumor volume at baseline (57.1 vs. 52.4, p &gt; 0.05) in HIF 1α positive and negative groups respectively. Low dose radiation and chemotherapy significantly reduced the tumor volume in bulky hypoxic tumors. The tumor volume reduction rate (TVRR) was significantly higher in hypoxic group (TVRR HIF_neg vs. TVRR HIF_pos 68.9 vs. 86.3, p = 0.02, t-test). There was significant improvement of diffusion MRI derived apparent diffusion coefficient (ADC) in hypoxic tumors with low dose radiation and chemotherapy (0.75 vs. 1.27, p = 0.12, Wilcoxon signed-rank test). Median score of percentage of hypoxic cells after neoadjuvant treatment were significantly higher in patients who developed subsequent local recurrence than the rest of the group (77% vs. 5% p = 0.009, Mann Whitney U test). Conclusion: Overall all HIF 1 positivity was 42% in the present study. A predominantly perinuclear pattern of HIF 1 staining was found in cervix cancer. Low dose radiation and chemotherapy significantly reduced the hypoxic tumor bulk in cervical cancer.

Study question What is the effect of low dose radiation on follicle count in sheep ovaries? Summary answer Even low dose radiation has a negative impact on the follicle count in sheep ovaries. What is known already Radiotherapy is a corner stone of state-of-the-art cancer treatment, especially in young cancer patients. Survival rates are constantly rising, resulting in long-term survivors with potential child wish. High doses of radiation lead to a permanent damage to the ovaries. Little is known about the damage after low dose radiation to the ovaries including both follicles and stroma. Study design, size, duration Prospective ongoing study, including n = 41 sheeps and 942 ovarian punches (Ø 3mm). So far, n = 12 sheep and n = 120 punches were analysed between April 2020 and January 2022. After finishing the experiments with sheep ovarian tissue, we will continue with a mouse model and human ovarian tissue. Participants/materials, setting, methods 942 cortex punches out of a total of n = 41 sheep were obtained and cryopreserved. After thawing the punches were radiated with a dose of 0.0, 0.5, or 9.0 Gy using a cesium 137 radionuklide source (GSR C1, GammaService Medical GmbH). The punches were fixed in formalin, embedded in paraffin, cut into serial sections of 3-5 µm and stained with Hematoxylin and Eosin for follicle counting as well as Caspase 3 and Ki67. Main results and the role of chance Follicle loss was already observed after low dose radiation (0.5 Gy). Mean follicle count after 0 Gy, 0.5 Gy, and 9 Gy were 7.5, 2.3 and 1.8, respectively. While after 0 Gy, no signs of degeneration were visible, after radiation with 9 Gy follicles showed strong signs of degeneration including disorganization of granulosa cells, pyknosis and stromal irregularities. Limitations, reasons for caution Limitations of our study include the pilot character and therefore small sample size. The presented data only display part of the overall project including also an in-vivo mouse model. Wider implications of the findings As even low dose radiation seems to damage ovarian follicles, further in-vivo studies are needed to confirm these results. Moreover, fertility preservation methods need to be offered consequently to young cancer patients receiving radiotherapy. Trial registration number 25