Objective To investigate the role of the O-6-methylguanine-DNA methyltransferase (MGMT) gene-3′ untranslated region (UTR) microRNA-associated single nucleotide polymorphism (miRSNP) (rs7896488 G>A) in affecting miR-4297-targeted modulation of MGMT in senescence of lung cells with polymorphic genotypes induced by fractionated low dose ionizing radiation (LDIR). Methods i) MiRSNPs were predicted and screened using bioinformatics, and DNA from two types of lung cells, A549 cells and human bronchial epithelioid cells (HBE cells), was extracted for target gene sequencing. After co-transfection of pGL3c-MGMT-3′UTR-rs7896488 G>A reporter gene recombinant plasmid, pRL-TK Vector with micrON mimic NC #22 or micrON hsa-miR-4297 mimic (set up as the mimic NC group and the miR-4297 mimic group) in these two types of lung cells, dual luciferase reporter gene assay was performed. The relative expression of MGMT mRNA was detected by real-time fluorescence quantitative polymerase chain reaction, and the relative expression of MGMT protein was detected by Western blotting. ii) These two types of lung cells were randomly divided into the control group and irradiation group, which received either 0 or 100 mGy X-rays irradiation seven times. After irradiation, the cells were transfected with either micrON mimic NC #22 or micrON hsa-miR-4297 mimic, resulting in mimic NC + control group, miR-4297 mimic + control group, mimic NC + irradiation group, and miR-4297 mimic + irradiation group. Cells were collected for senescence-associated-β-galactosidase (SA-β-Gal) staining, and the relative expression of matrix metalloproteinase-9 (MMP-9) and chemokine (C-X-C motif) ligand-1 (CXCL-1) proteins was detected via Western blotting. Results i) The rs7896488 G>A was the miRSNP located in the conserved binding region targeted by miR-4297 in the MGMT gene 3′UTR. A549 cells were the rs7896488 GG wild-type homozygous genotype, while HBE cells were the rs7896488 GA heterozygous mutant genotype. In the miR-4297 mimic group, A549 and HBE cells carrying the rs7896488 G allele showed significantly lower dual-luciferase activity compared with that in the mimic NC group (both P<0.01). However, there was no significant difference in dual-luciferase activity between the two groups in both A549 and HBE cells carrying the rs7896488 A allele (both P>0.05). The relative expression levels of MGMT mRNA and MGMT protein of A549 cells in the miR-4297 mimic group were lower than those in the mimic NC group (both P<0.05). However, there was no significant difference in MGMT mRNA and MGMT protein of HBE cells between these two groups (both P>0.05). ii) The relative activity of SA-β-Gal and the relative expression of MMP-9 and CXCL-1 proteins of A549 cells in the miR-4297 mimic+irradiation group were higher than those in the mimic NC + control group, the miR-4297 mimic + control group, and the mimic NC + irradiation group (all P<0.05). The relative activity of SA-β-Gal and the relative expression of MMP-9 and CXCL-1 proteins of HBE cells in the miR-4297 mimic + irradiation group were higher than those in the mimic NC + control group and the miR-4297 mimic + control group (all P<0.05), while there was no significant difference compared with those in the mimic NC + irradiation group (all P>0.05). Conclusion MGMT-3′UTR-miRSNP rs7896488 G>A plays a role in LDIR-induced senescence of lung cells with different polymorphic genotypes by affecting miR-4297-targeted regulation of MGMT.

Objective To investigate the effects of fractionated low-dose ionizing radiation (LDIR) on the ferroptosis in human bronchial epithelial (HBE) cells as well as the associated differentially expressed genes (DEGs), biological processes, and signaling pathways. Methods HBE cells were exposed to different single doses of X-ray irradiation (0, 25, 50, 75, and 100 mGy) for 24, 48, and 72 h, respectively. The change in cell viability was detected by MTT assay. Cells were irradiated with 0, 25, 50, and 100 mGy X-rays 5 times, with 48 h between each irradiation and a dose rate of 50 mGy/min. Cells were harvested 24 h after irradiation for the measurement of the expression of ferroptosis-related genes SLC7A11 and GPX4 at the mRNA and protein levels, cellular iron content, and the expression of FTH1 and FTL mRNAs. High-throughput sequencing was used to screen for the DEGs in each dose group, followed by Gene Ontology-Biological Process (GO-BP) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and Gene Set Enrichment Analysis (GSEA). Results Compared with the control group, single-dose LDIR significantly increased cell proliferation at 75 mGy after 24 h (P < 0.05), at 50, 75, and 100 mGy after 48 h (P < 0.05), and at 75 and 100 mGy after 72 h (P < 0.05). Compared with the control group, at the end of the fifth fractionated LDIR, SLC7A11 and GPX4 mRNAs decreased at all doses (P < 0.05), SLC7A11 protein decreased at all doses, GPX4 protein decreased at 25 and 100 mGy, iron content increased at all doses, and FTH1 and FTL mRNAs decreased at all doses (P< 0.05). Sequencing analysis identified 248, 30, and 291 DEGs and 10, 2, and 9 ferroptosis-associated genes at the three doses compared to the control. Gene Ontology-Biological Process analysis showed that DEGs were mainly enriched in biological processes such as response to lipids, cell death, and response to unfolded proteins. Kyoto Encyclopedia of Genes and Genomes analysis showed that DEGs were mainly enriched in the JAK-STAT signaling pathway, lipids and atherosclerosis, ferroptosis, protein processing in the endoplasmic reticulum, and FoxO signaling pathway. Gene set enrichment analysis showed that DEGs were mainly enriched in ferroptosis, fatty acid degradation, and glutathione metabolism. Conclusion Fractionated low-dose radiation induced ferroptosis in HBE cells, and DEGs were predominantly enriched in biological processes and signaling pathways related to inflammation, ferroptosis, and endoplasmic reticulum stress.

Objective To investigate the mechanism of fractionated low-dose ionizing radiation (LDIR) in the induction of EA.hy926 cell senescence. Methods EA.hy926 cells were irradiated with X-ray at 0, 50, 100, and 200 mGy × 4, respectively, and cultured for 24, 48, and 72 h. Several indicators were measured, including the levels of cellular senescence-associated β-galactosidase (SA-β-gal) staining, mRNA levels of senescence-associated cell cycle protein-dependent kinase inhibitor genes CDKN1A and CDKN2A, reactive oxygen species (ROS), total antioxidant capacity (T-AOC), and phosphorylated H2A histone family member X (γ-H2AX). Results After 4 fractionated LDIR, compared with the control group, the treatment groups showed increased nucleus area, blurred cell edge, and increased SA-β-gal positive area (P < 0.05) at 24, 48 and 72 h. After 4 fractionated LDIR, the mRNA level of CDKN1A increased in the 100 and 200 mGy × 4 groups at 24 and 48 h (P < 0.05), and CDKN2A mRNA level increased in the 100 and 200 mGy × 4 groups at 48 and 72 h (P < 0.05). The fluorescence intensity of ROS increased in treatment groups at 24, 48, and 72 h after 4 fractionated LDIR (P < 0.05). After 4 fractionated LDIR, the T-AOC level increased in the 100 and 200 mGy × 4 groups at 24 h (P < 0.05), and T-AOC level increased in all treatment groups at 48 and 72 h (P < 0.05). After 4 fractionated LDIR, γ-H2AX fluorescence intensity increased in all treatment groups at 24 h (P < 0.05), and the fluorescence intensity increased in the 100 and 200 mGy × 4 groups at 48 and 72 h (P < 0.05). Conclusion Fractionated LDIR can induce cellular senescence in EA.hy926 cells by impacting the cellular oxidation-antioxidation and oxidative damage levels, and the effects were relatively evident at 100 and 200 mGy.

Objective To explore the differentially expressed mRNAs and related biological processes and pathways in fractional low-dose ionizing radiation (LDIR)-induced senescence of normal human bronchial epithelial (HBE) cells by high-throughput mRNA sequencing and bioinformatics techniques. Methods Senescence-associated β-galactosidase staining and senescence-associated secretion phenotype gene mRNA and protein expression levels were measured at 24 and 48 h after irradiating HBE cells 7 times at doses of 0, 50, 100, and 200 mGy, respectively. The differentially expressed genes were screened by high-throughput sequencing for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Results The senescence-positive area of fractional low-dose irradiated HBE cells increased in a dose-dependent manner (P < 0.05). The mRNA levels and protein expression of transforming growth factor-β1(TGF-β1) and matrix metalloproteinase-9(MMP-9) genes were increased in the 100 mGy × 7 and 200 mGy × 7 groups at 24 and 48 h after the end of irradiation compared with the control group. High-throughput sequencing showed that there were 882, 475, and 1205 differentially expressed mRNAs in each dose group compared with the control group. GO analysis showed that the differentially expressed mRNAs in each dose group were mainly enriched in biological processes such as cell cycle regulation, regulation of nitrogen compound metabolic process, regulation of cell division and response to stimulus. KEGG analysis showed that the differentially expressed mRNAs were mainly enriched in the pathways of cell cycle, cell senescence, and ferroptosis. Conclusion Fractional LDIR induced senescence in HBE cells, and differentially expressed mRNA-associated biological processes and pathways in senescent cells are related to cell cycle and cell senescence.

Objective:To investigate the changes in liver injury and oxidative-antioxidant level in mice exposed to X-rays at varying doses.Methods:Fifty-four 8-week-old male C57BL/6J mice were divided into three groups, namely the control, 2 Gy irradiation, and 4 Gy irradiation groups. Then, each of the groups was further divided by days post-irradiation (i.e., 1, 3, and 7 d), and so nine sub-groups ( n = 6). After irradiation was performed as planned, all the mice were dissected and weighed, and their liver indexes were calculated to determine any histopathological changes in the liver. The peripheral blood cell count and the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) were detected. Furthermore, spectrophotometry was also used to determine the superoxide dismutase (SOD) activity, the malondialdehyde (MDA) concentration, and the reduced glutathione (GSH) concentration in liver tissues. Results:Compared to the control group, mice undergoing irradiation exhibited a significant reduction in body weight ( F = 84.03, 27.11, 25.50, P < 0.001), but significantly increased liver indexes ( F = 28.40, 17.75, P <0.001) at 1, 3, and 7 d post-irradiation. Pathological observations of these mice revealed liver injury, which proved related to dose and time course. The counts of leukocytes, neutrophils, and lymphocytes in peripheral blood decreased significantly ( F = 8.42-22.91, P < 0.05), trending downward with an increase in the radiation dose. For mice in the 4 Gy irradiation group, their AST and ALT levels increased significantly at 1 d post-irradiation ( H = 7.24, 7.82, P < 0.05), and their ALP levels rose notably at 1 and 3 d post-irradiation ( F = 11.86, 9.75, P < 0.05). Furthermore, their MDA and SOD levels initially rose and then dropped but their GSH levels exhibited an opposite trend at 1, 3, and 7 d post-irradiation. There was a positive correlation between their MDA levels in the liver and the degree of damage to histopathological lesions at 1, 3, and 7 d post-irradiation ( r = 0.30, P < 0.001). Conclusions:A model for radiation-induced liver injury of mice was preliminarily established in this study. It can be concluded that X-rays at varying doses affect the severity of liver injury, pathological grade, peripheral blood cell count, liver function index, and liver oxidative and antioxidant levels of mice, presenting a certain relationship between dose and time course effects.

Objective To investigate the status of metabolically unhealthy status (MUS) and its influencing factors in male residents living around a uranium mine in Guangdong Province. Methods A total of 867 local male residents born and living around a uranium mine in Guangdong Province were selected as the study subjects using two-stage random sampling method. The residents were divided into 10 km- and 20 km- radius groups, according to their living distance <10 km or 10-20 km from the uranium mine. Blood pressure, fasting blood glucose, and blood lipid levels were tested among the study subjects. The influencing factors of MUS and its components were analyzed by multiple logistic regression. Results The detection rate of MUS was 42.2%. The detection rates of MUS component such as elevated diastolic blood pressure, elevated systolic blood pressure, elevated fasting blood glucose, elevated triglyceride and low high-density lipoprotein cholesterol (HDL-C) were 48.8%, 60.9%, 11.9%, 40.7% and 19.3%, respectively. The MUS detection rate in the 10 km group was lower than that in the 20 km group (38.5% vs 45.9%, P<0.05). The result of multivariate logistic regression analysis showed that subjects aged >50 years had a higher risk of MUS and elevated systolic blood pressure than those aged ≤ 50 years (all P<0.05). Drinkers had a higher risk of MUS, elevated systolic blood pressure, elevated diastolic blood pressure, elevated triglyceride, and low HDL-C than non-drinkers (all P<0.05). Those who ate fruit occasionally had a higher risk of MUS than those who ate fruit regularly (P<0.05). Overweight and obese individuals had a higher risk of MUS, elevated systolic blood pressure, elevated diastolic blood pressure, elevated triglyceride, and low HDL-C than those with normal body mass (all P<0.05). Individuals in the 20 km group had a higher risk of MUS and low HDL-C than the 10 km group (all P<0.05). Conclusion The risk factors of MUS detection among male residents living around the uranium mines are age > 50 years, drinking, occasional fruit intake, and being overweight or obese. Age > 50 years, drinking alcohol, overweight and obesity can affect the detection of MUS components in different degrees. Environmental radiation levels have not been identified as a risk factor for MUS in these study subjects.

Objective To investigate the effects of lowdose ionizing radiation (LDIR) on oxidative stress and damage repair in human bronchial epithelial (HBE) cells. Methods HBE cells were divided into 0, 50, 100, and 200 mGy groups, and cultured for 24 and 48 h after X-ray irradiation, respectively. The cell viability, levels of glutathione (GSH), malondialdehyde (MDA), and 8-hydroxy-2’-deoxyguanosine (8-OHdG), and transcriptional levels of DNA damage repair genes PPP2R2D and TP53 were measured. Results At 24 h after irradiation, there was no significant difference in the cell viability between the dose groups and the control group (P > 0.05); all dose groups had significantly increased MDA level, dose-dependently decreased GSH level, dose-dependently increased 8-OHdG level, and significantly increased mRNA level of PPP2R2D gene (all P < 0.05); the mRNA expression level of TP53 gene was significantly increased in the 50 mGy group (P < 0.05). At 48 h after irradiation, there were the highest cell viability, significantly decreased MDA and 8-OHdG levels, and significantly increased mRNA expression levels of PPP2R2D and TP53 genes in the 50 mGy group compared with the control group (all P < 0.05); the GSH level in the 100 mGy group was significantly increased (P < 0.05). Conclusion LDIR, especially radiation at 50 mGy, can affect the oxidative-antioxidant level in HBE cells and the transcript-level differential expression of DNA damage repair genes.

Objective:To analyze the serum lipid levels, and its influencing factors, of male residents around an uranium mine in order to provide a scientific basis for health risk assessment for such residents.Methods:With such a mine as the center, the surveyed subjects were divided into four groups as within 5, 10, 15 and 20 km of this mine, respectively. These male residents living around the mine were randomly selected as subjects. A health questionnaire survey was conducted among the subjects. The indicator such as height, weight and blood pressure were measured by means of the standard method. Peripheral venous blood was extracted from the subjects, and their venous blood glucose and serum lipid were detected. The levels of serum lipid and detectable rates of abnormal serum lipid were analyzed by using univariate analysis, and multivariate logistic regression analysis was used to analyze the influencing factors of dyslipidemia.Results:A total of 867 males at age 40 to 69 was included in the vicinity of the mine. The mean levels ( ± s) of TC, TG, LDL-C, and HDL-C were (5.46±1.11), (1.92±1.64), (3.19±1.02), and (1.39±0.43) mmol/L, respectively. 384 subjects with dyslipidemia were totally detected in the residents, and the detection rate was 44.29% (384/867). Of the residents with dyslipidemia, the majority was abnormal in two lipid related indexes (45.57%, 175/384). Univariate analysis result showed that there was statistically significant difference in TG level in different distance groups ( F=3.34, P<0.05). There were statistically significant differences in the abnormal detection rates of TG and HDL-C in subjects in different distance groups ( χ2=9.52, 10.18, P<0.05). The detection rates of dyslipidemia were significantly different in the groups of BMI, blood pressure and blood glucose ( χ2=45.91, 32.31, 11.42, P<0.05). Multivariate logistic regression analysis showed that excluding marital status and degree of education, the BMI, blood pressure and blood glucose all had an impact on dyslipidemia. The residents with overweight ( OR=2.08, 95% CI: 1.52-2.86) and obeseness ( OR=2.88, 95% CI: 1.58-5.24) had a higher risk for dyslipidemia than those with normal weight. The risks for dyslipidemia in the residents with hypertension ( OR=1.94, 95% CI: 1.45-2.60) and hyperglycemia ( OR= 2.17, 95% CI: 1.27-3.69) were higher than those with normal blood pressure and blood glucose, respectively. Conclusions:The detection rate of dyslipidemia is higher in male residents around the mine. The BMI, alcohol consumption, blood pressure, blood glucose and distance from the mine are influencing dyslipidemia and other relevant indexes. Overweight is an independent risk factor for dyslipidemia and its components. The distances from uranium mine has no significant effect on the dyslipidemia of male residents.

With the development of nuclear energy and the wide application of ionizing radiation, more and more occupational populations and the public are exposed to low-dose ionizing radiation. Consequently, the research on human health effects of exposure to low-dose ionizing radiation, including carcinogenic and non-carcinogenic effects, have become a hot topic in the field of public health. The biological effects caused by low-dose ionizing radiation mainly depend on the physical property, duration, dose, and dose rate of ionizing radiation. At present, there is no consensus on the effects of long-term exposure to low-dose ionizing radiation on human health. This article reviews the research on the health effects of long-term exposure to low-dose ionizing radiation at home and abroad, and provides a scientific basis for research on the health effects, influence mechanism, and protection strategies of long-term exposure to low-dose ionizing radiation.

Objective:To explore the value of thyroid radioactive iodine uptake (RAIU) on predicting the residual activity in patients with differentiated thyroid carcinoma (DTC) after administration of 131I. Methods:A total of 178 patients (63 males, 115 females, age: (39.8±11.4) years) with DTC who underwent initial treatment of 131I in Suzhou Science & Technology Town Hospital between August 2018 and April 2019 were enrolled in this retrospective study. RAIU test and thyroid imaging were performed before 131I treatment. Patients were divided into 3 groups according to the thyroid remnant showed by thyroid imaging: no remnant group, a little remnant group, and obvious remnant group. Radiation dose equivalent rates at different time points (immediately/24 h/48 h/72 h after injection of 131I) were measured to estimate the residual activity of 131I after administration. RAIU and residual activity at 72 h among different thyroid remnant groups were compared by one-way analysis of variance. Relationship between RAIU/ 131I therapeutic dose and residual activity at 72 h was analyzed by Pearson correlation analysis. The linear regression equation between RAIU and residual activity at 72 h after treatment was established. Results:The 3 h RAIU in no remnant group ( n=45), a little remnant group ( n=101), and obvious remnant group ( n=32) were (4.77±1.46)%, (5.53±1.70)% and (8.92±3.75)%, respectively ( F=39.35, P<0.01), and the 24 h RAIU was also significantly different among those 3 groups ((1.54±0.88)%, (3.41±2.55)%, (13.52±8.59)%; F=91.52, P<0.01). The residual activity at 72 h in no remnant group, a little remnant group, and obvious remnant group were (81.70±25.61), (108.24±51.58) and (283.07±133.72) MBq, respectively ( F=92.84, P<0.01). There was a significant positive correlation between RAIU and the residual activity at 72 h (3 h: r=0.753, 24 h: r=0.817, both P<0.01). The linear regression equations between RAIU at 3 h and 24 h and the residual activity at 72 h were y=28.88 x-38.42 and y=13.87 x+ 67.01, respectively. When RAIU was higher than 24.01% at 3 h or 15.18% at 24 h, the residual activity at 72 h after treatment was likely to exceed 400 MBq. There was little correlation between 131I therapeutic dose and the residual activity at 72 h after treatment ( r=0.119, P>0.05). Conclusion:RAIU can be used to predict the residual activity at 72 h after treatment in DTC patients who underwent initial 131I treatment.