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The effects of low-dose radiation exposure remain a controversial topic in radiation biology. This study compares early (0.5, 4, 24, 48, and 72 h) and late (5, 10, and 15 cell passages) post-irradiation changes in γH2AX, 53BP1, pATM, and p-p53 (Ser-15) foci, proliferation, autophagy, and senescence in primary fibroblasts exposed to 100 and 2000 mGy X-ray radiation. The results show that exposure to 100 mGy significantly increased γH2AX, 53BP1, and pATM foci only at 0.5 and 4 h post irradiation. There were no changes in p-p53 (Ser-15) foci, proliferation, autophagy, or senescence up to 15 passages post irradiation at the low dose.

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The radioprotective properties of copper chlorophyllin (100 and 150 µg/g), the standard antioxidant trolox (100 and 200 µg/g), and the standard radioprotector indralin (100 and 150 µg/g) were compared in male ICR mice (CD-1) subjected to whole-body irradiation (X-ray radiation) in doses of 6, 6.5, and 6.75 Gy. Animal survival was analyzed using the Kaplan-Meier method, and the significance of differences was evaluated using the log-rank test method. Dose change factors determined using the Phinney probit analysis were 1.1, 1.0, and 1.8 for chlorophyllin, trolox, and indralin at a dose of 100 µg/g body weight, respectively. The insignificant radioprotective properties of chlorophyllin and their absence in trolox when administered prophylactically do not rule out their possible radioprotective properties like a radiomodulator that protects the body after irradiation.

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Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding materials were developed using low-density polyethylene (LDPE) mixed with four different filler materials. These four materials are cement, cement with iron oxide, cement with aluminum oxide, and cement with bismuth oxide. Different weight percentages were used including 5%, 15%, and 50% of the cement filler with LDPE. Furthermore, different weight percentages of different combinations of the filler materials were used including 2.5%, 7.5%, and 25% (i.e., cement and iron oxide, cement and aluminum oxide, cement and bismuth oxide) with LDPE. Bismuth oxide was a nanocomposite, and the remaining oxides were micro-composites. Characterization included structural properties, physical features, mechanical and thermal properties, and radiation shielding efficiency for the prepared composites. The results show that a clear improvement in the shielding efficiency was observed when the filler materials were added to the LDPE. The best result out of all these composites was obtained for the composites of bismuth oxide (25 wt.%) cement (25 wt.%) and LDPE (50 wt.%) which have the lowest measured mean free path (MFP) compared with pure LDPE. The comparison shows that the average MFP obtained from the experiments for all the eight energies used in this work was six times lower than the one for pure LDPE, reaching up to twelve times lower for 60 keV energy. The best result among all developed composites was observed for the ones with bismuth oxide at the highest weight percent 25%, which can block up to 78% of an X-ray.

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BACKGROUND: Efficient classification of T-acute lymphoblastic leukemia (T-ALL) involves considering various factors, such as age, white blood cell count, and chromosomal alterations. However, studying protein markers are crucial to improving T-ALL patients' diagnosis and treatment. A study analyzing the expression of proteomes was conducted to identify promising early-stage biomarkers for T-ALL patients METHODS: Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyze the blood proteins of both patients and healthy individuals to identify new biomarkers for T-ALL. The findings were validated by RT-PCR, ELISA and computational analysis RESULTS: The study identified 1467 proteins in the blood, of which nine were upregulated and 35 were downregulated by more than 2-fold. T-ALL patients showed a significant increase in specific disease-related proteins, such as eleven-nineteen lysine-rich leukemia protein, triggering receptor expressed on myeloid cells 1, cisplatin resistance-associated-overexpressed protein, X-ray radiation resistance-associated protein 1, tumor necrosis factor receptor superfamily member 10D, protein S100-A8, and copine-4, by more than 3-fold CONCLUSION: The findings of this study provide a valuable protein map of leukemic cells and identify potential biomarkers for leukemic aggressiveness. However, further studies using larger T-ALL patient samples must confirm these preliminary results.

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X-ray radiation information storage, characterized by its ability to detect radiation with delayed readings, shows great promise in enabling reliable and readily accessible X-ray imaging and dosimetry in situations where conventional detectors may not be feasible. However, the lack of specific strategies to enhance the memory capability dramatically hampers its further development. Here, we present an effective anion substitution strategy to enhance the storage capability of NaLuF4:Tb3+ nanocrystals attributed to the increased concentration of trapping centers under X-ray irradiation. The stored radiation information can be read out as optical brightness via thermal, 980 nm laser, or mechanical stimulation, avoiding real-time measurement under ionizing radiation. Moreover, the radiation information can be maintained for more than 13 days, and the imaging resolution reaches 14.3 lp mm-1. These results demonstrate that anion substitution methods can effectively achieve high storage capability and broaden the application scope of X-ray information storage.

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BACKGROUND: The modern world faces a growing concern about the possibility of accidental radiation events. The Hematopoietic system is particularly vulnerable to radiationinduced apoptosis, which can lead to death. Metformin, a drug used to treat diabetes, has been shown to protect normal cells and tissues from the toxic effects of radiation. This study aimed to evaluate the effectiveness of metformin in mitigating radiation injury to the gastrointestinal and hematological systems of rats. MATERIALS AND METHODS: The study involved 73 male rats. After total body irradiation with 7.5 Gy of X-rays, rats were treated with metformin. Seven days later, the rats were sacrificed and blood samples were taken for evaluation. RESULTS: The study found that metformin was not effective in mitigating radiation injury. The histopathological assessment showed no significant changes in goblet cell injury, villi shortening, inflammation, or mucous layer thickness. In terms of biochemical evaluation, metformin did not significantly affect oxidative stress markers, but irradiation increased the mean MDA level in the radiation group. The complete blood count revealed a significant decrease in WBC and platelet, counts in the radiation group compared to the control group, but no significant difference was found between the radiation and radiation + metformin groups. CONCLUSION: In conclusion, metformin may not be a good option for reducing radiation toxicity after accidental exposure. Despite treatment, there was no improvement in platelet, white blood cell, and lymphocyte counts, nor was there any decrease in oxidative stress. Further research is needed to explore other potential treatments for radiation injury.

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The effects of physical factors such as radiation (electromagnetic, microwave, infrared, laser, UVC, and X-ray) and high temperature, as well as chemical factors (controlled atmosphere) on the level of global DNA cytosine methylation in C. albicans ATCC 10231 cells were investigated. Prolonged exposure to each type of radiation significantly increased the DNA methylation level. In addition, the global methylation level in C. albicans cells increased with the incubation temperature. An increase in the percentage of methylated DNA was also noted in C. albicans cells cultured in an atmosphere with reduced O2. In contrast, in an atmosphere containing more than 3% CO2 and in anaerobic conditions, the DNA methylation level decreased relative to the control. This study showed that prolonged exposure to various types of radiation and high temperature as well as reduced O2 in the atmosphere caused a significant increase in the global DNA methylation level. This is most likely a response protecting DNA against damage, which at the same time can lead to epigenetic disorders, and in consequence can adversely affect the functioning of the organism.

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We studied changes in the number of residual γH2AX foci in cultured human fibroblasts with different expression of the cell proliferation marker protein Ki-67 24, 48, and 72 h after exposure to X-ray radiation in doses of 2-10 Gy. It was shown that, regardless of the expression of Ki-67, the number of residual γH2AX foci in irradiated cells linearly depends on the absorbed dose of X-ray radiation. However, the quantitative yield of residual γH2AX foci per unit of the absorbed dose in Ki-67+ cells 24 and 48 h after irradiation was higher than in Ki-67- cells by 1.8 and 2.0 times, respectively. In Ki-67- cells, the quantitative yield of residual γH2AX foci per unit of absorbed dose decreases by ~1.7 times with increasing the time after irradiation from 24 to 72 h. For the purposes of practical radiation biodosimetry, it can be recommended to quantify residual γH2AX foci in non-proliferating cells at least 72 h after irradiation.

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Radiation therapy and unwanted radiological or nuclear exposure, such as nuclear plant accidents, terrorist attacks, and military conflicts, pose serious health issues to humans. Dysfunction of the intestinal epithelial barrier and the leakage of luminal antigens and bacteria across the barrier have been linked to various human diseases. Intestinal permeability is regulated by intercellular structures, termed tight junctions (TJs), which are disrupted after radiation exposure. In this study, we investigated radiation-induced alterations in TJ-related proteins in an intestinal epithelial cell model. Caco-2 cells were irradiated with 2, 5, and 10 Gy and harvested 1 and 24 h after X-ray exposure. The trypan blue assay revealed that cell viability was reduced in a dose-dependent manner 24 h after X-ray exposure compared to that of non-irradiated cells. However, the WST-8 assay revealed that cell proliferation was significantly reduced only 24 h after radiation exposure to 10 Gy compared to that of non-irradiated cells. In addition, a decreased growth rate and increased doubling time were observed in cells irradiated with X-rays. Intestinal permeability was significantly increased, and transepithelial electrical resistance values were remarkably reduced in Caco-2 cell monolayers irradiated with X-rays compared to non-irradiated cells. X-ray irradiation significantly decreased the mRNA and protein levels of ZO-1, occludin, claudin-3, and claudin-4, with ZO-1 and claudin-3 protein levels decreasing in a dose-dependent manner. Overall, the present study reveals that exposure to X-ray induces dysfunction of the human epithelial intestinal barrier and integrity via the downregulation of TJ-related genes, which may be a key factor contributing to intestinal barrier damage and increased intestinal permeability.

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DNA repair (DNA damage) foci observed 24 h and later after irradiation are called "residual" in the literature. They are believed to be the repair sites for complex, potentially lethal DNA double strand breaks. However, the features of their post-radiation dose-dependent quantitative changes and their role in the processes of cell death and senescence are still insufficiently studied. For the first time in one work, a simultaneous study of the association of changes in the number of residual foci of key DNA damage response (DDR) proteins (γH2AX, pATM, 53BP1, p-p53), the proportion of caspase-3 positive, LC-3 II autophagic and SA-ß-gal senescent cells was carried out 24-72 h after fibroblast irradiation with X-rays at doses of 1-10 Gy. It was shown that with an increase in time after irradiation from 24 h to 72 h, the number of residual foci and the proportion of caspase-3 positive cells decrease, while the proportion of senescent cells, on the contrary, increases. The highest number of autophagic cells was noted 48 h after irradiation. In general, the results obtained provide important information for understanding the dynamics of the development of a dose-dependent cellular response in populations of irradiated fibroblasts.

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Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical-chemical-structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health.

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The development of treatment strategies for skeletal diseases relies on the understanding of bone mechanical properties in relation to its structure at different length scales. At the microscale, indention techniques can be used to evaluate the elastic, plastic, and fracture behaviour of bone tissue. Here, we combined in situ high-resolution SRµCT indentation testing and digital volume correlation to elucidate the anisotropic crack propagation, deformation, and fracture of ovine cortical bone under Berkovich and spherical tips. Independently of the indenter type we observed significant dependence of the crack development due to the anisotropy ahead of the tip, with lower strains and smaller crack systems developing in samples indented in the transverse material direction, where the fibrillar bone ultrastructure is largely aligned perpendicular to the indentation direction. Such alignment allows to accommodate the strain energy, inhibiting crack propagation. Higher tensile hoop strains generally correlated with regions that display significant cracking radial to the indenter, indicating a predominant Mode I fracture. This was confirmed by the three-dimensional analysis of crack opening displacements and stress intensity factors along the crack front obtained for the first time from full displacement fields in bone tissue. The X-ray beam significantly influenced the relaxation behaviour independent of the tip. Raman analyses did not show significant changes in specimen composition after irradiation compared to non-irradiated tissue, suggesting an embrittlement process that may be linked to damage of the non-fibrillar organic matrix. This study highlights the importance of three-dimensional investigation of bone deformation and fracture behaviour to explore the mechanisms of bone failure in relation to structural changes due to ageing or disease. STATEMENT OF SIGNIFICANCE: Characterising the three-dimensional deformation and fracture behaviour of bone remains essential to decipher the interplay between structure, function, and composition with the aim to improve fracture prevention strategies. The experimental methodology presented here, combining high-resolution imaging, indentation testing and digital volume correlation, allows us to quantify the local deformation, crack propagation, and fracture modes of cortical bone tissue. Our results highlight the anisotropic behaviour of osteonal bone and the complex crack propagation patterns and fracture modes initiating by the intricate stress states beneath the indenter tip. This is of wide interest not only for the understanding of bone fracture but also to understand other architectured (bio)structures providing an effective way to quantify their toughening mechanisms in relation to their main mechanical function.

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In photosystem II (PSII), the O3 and O4 sites of the Mn4CaO5 cluster form hydrogen bonds with D1-His337 and a water molecule (W539), respectively. The low-dose X-ray structure shows that these hydrogen bond distances differ between the two homogeneous monomer units (A and B) [Tanaka et al., J. Am Chem. Soc. 2017, 139, 1718]. We investigated the origin of the differences using a quantum mechanical/molecular mechanical (QM/MM) approach. QM/MM calculations show that the short O4-OW539 hydrogen bond (~2.5 Å) of the B monomer is reproduced when O4 is protonated in the S1 state. The short O3-NεHis337 hydrogen bond of the A monomer is due to the formation of a low-barrier hydrogen bond between O3 and doubly-protonated D1-His337 in the overreduced states (S-1 or S-2). It seems plausible that the oxidation state differs between the two monomer units in the crystal.

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Ionizing radiation-induced damage in cancer and normal cells leads to apoptosis and cell death, through the intracellular oxidative stress, DNA damage and disorders of their metabolism. Irradiation doses that do not lead to the death of tumor cells can result in the emergence of radioresistant clones of these cells due to the rearrangement of metabolism and the emergence of new mutations, including those in the genes responsible for DNA repair. The search for the substances capable of modulating the functioning of the tumor cell repair system is an urgent task. Here we analyzed the effect of cerium(III) fluoride nanoparticles (CeF3 NPs) on normal (human mesenchymal stem cells-hMSC) and cancer (MCF-7 line) human cells after X-ray radiation. CeF3 NPs effectively prevent the formation of hydrogen peroxide and hydroxyl radicals in an irradiated aqueous solution, showing pronounced antioxidant properties. CeF3 NPs are able to protect hMSC from radiation-induced proliferation arrest, increasing their viability and mitochondrial membrane potential, and, conversely, inducing the cell death of MCF-7 cancer cells, causing radiation-induced mitochondrial hyperpolarization. CeF3 NPs provided a significant decrease in the number of double-strand breaks (DSBs) in hMSC, while in MCF-7 cells the number of γ-H2AX foci dramatically increased in the presence of CeF3 4 h after irradiation. In the presence of CeF3 NPs, there was a tendency to modulate the expression of most analyzed genes associated with the development of intracellular oxidative stress, cell redox status and the DNA-repair system after X-ray irradiation. Cerium-containing nanoparticles are capable of providing selective protection of hMSC from radiation-induced injuries and are considered as a platform for the development of promising clinical radioprotectors.

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Cerenkov radiation (CR) from radionuclides and megavoltage X-ray radiation can act as an in situ light source for deep cancer theranostics, overcoming the limitations of external light sources. Despite the blue-weighted emission and low quantum yield of CR, activatable probes-mediated CR can enhance the in-vivo diagnostic signals by Cerenkov resonance energy transfer and also can produce therapeutic effects by reactive species generation/drug release, greatly promoting the biomedical applications of CR. In this review, we describe the principles and sources of CR, construction of CR-activated probes and their application to tumor optical imaging and therapy. Finally, future prospects for the design and biomedical application of CR-activated probes are discussed.

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The aim of the study was to evaluate the possibility of increasing the radioprotective potential of peroxiredoxin 6 (Prdx6) and its mutant form S32A by their combined use with geldanamycin (GA) for 3T3 fibroblasts irradiated with X-rays at a dose of 6 Gy. The mutant enzyme S32A, which does not have phospholipase activity, exhibits a more pronounced radioprotective activity when combined with GA. The use of this combination of radioprotective drugs completely abolishes the peak of NF-κB activity in irradiated 3T3 cells. Another transcription factor, p53, which is an indicator of the level of cell apoptosis and increases upon irradiation, is also reduced by S32A in combination with GA. The low-molecular-weight protein p21, which is a marker of cell senescence and whose production increases upon irradiation, is also normalized when S32A is used in combination with GA. In addition, the use of this combination of radioprotective drugs significantly reduces the stress response of 3T3 cells to X-ray irradiation.

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Purpose: The "radiotherapy-pharmacokinetic" ("RT-PK") phenomenon refers to the fact that radiation can significantly alter the pharmacokinetic behavior of a drug. At present, it is not clear whether there is an "RT-PK" phenomenon that can affect apatinib during concurrent chemoradiotherapy. In this study, we used a rat irradiation model to study the effects of X-ray radiation on absorption, tissue distribution, and excretion of apatinib. Method: Healthy Sprague-Dawley (SD) rats were randomly divided into control and radiation groups. The radiation group was given an appropriate dose of abdominal X-ray radiation, while the control group was not given irradiation. After 24 h of recovery, both groups were given apatinib solution 45 mg/kg by gavage. A quantitative LC-MS/MS method was developed to determine the concentration of apatinib in the rats, so as to compare the differences between the control and radiation groups and thus investigate the modulating effect of radiation on the pharmacokinetics of apatinib in rats. Results: After abdominal X-ray irradiation, the area under the curve (AUC0-t) of apatinib in rat plasma decreased by 33.8% and 76.3% at 0.5 and 2 Gy, respectively. Clearance (CL) and volume of distribution (Vd) increased and were positively correlated with radiation dose. X-ray radiation significantly reduced the concentration of apatinib in the liver and small intestine, and there was no tissue accumulation. In excretion studies, we found that X-ray radiation reduced the cumulative excretion of apatinib in feces and urine by 11.24% and 86.17%, respectively. Conclusion: Abdominal X-ray radiation decreased plasma exposure, tissue distribution, and excretion of apatinib in rats, suggesting that the RT-PK phenomenon affects apatinib. We speculate that this RT-PK phenomenon is closely related to changes in metabolic enzymes in vivo. In clinical practice, when apatinib is combined with radiotherapy, attention should be paid to adjusting the dose of apatinib and optimizing the treatment plan to alleviate the adverse effects of this RT-PK phenomenon.

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Radiation can lead to various damages in the process of spermatogenesis that lead to a decrease in the number of sperm, an increase in spermatogenesis disorders, and defective sperm function. Radioprotectors are considered a good approach to reducing the damage caused by radiation. The goal of this work was to study how X-ray radiation affects testicular tissue and the process of spermatogenesis, as well as the radioprotective effects of selenium nanoparticles (SeNPs) and Lactobacillus casei (L. casei) as probiotic compounds, given alone or together. This study included 64 adult Syrian male mice weighing approximately 20 ± 5 g and aged 10 ± 1 weeks. Animals were randomly divided into eight groups: control group, SeNPs, probiotic, SeNPs and probiotic, X-ray radiation, SeNPs (X-ray), probiotic (X-ray), and SeNPs and probiotic (X-ray). Histology parameters and levels of oxidative stress biomarkers such as catalase, malondialdehyde, superoxide dismutase, and glutathione peroxidase were examined. In addition, the level of apoptosis was measured in testicular cells that had been treated with SeNPs and L. casei as a probiotic. The results showed that the administration of SeNPs or probiotic diminished the effects of X-ray radiation. These compounds induced a significant decreased in malondialdehyde, caspase 3, and caspase 9 gene levels and a remarkable increased in catalase, superoxide dismutase, and Catsper gene expression. SeNPs and probiotic exhibited a potent antioxidant effect and elevated the mean number of spermatogonia cells, sperm cell count, spermatogenesis percentage, and sperm motility percentage. The prescribed compound exhibited an ideal radioprotective effect with the ability to reduce the side effects of ionizing radiation and to protect normal tissues. SeNPs and probiotic inhibit testicular injury and improve the antioxidant state in male mice.

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The high-pressure phase-transition behaviour of metal-organic frameworks and coordination polymers upon varying degrees of X-ray irradiation are highlighted with four example studies. These show that, in certain cases, the radiation damage, while not extreme in changing unit-cell values, can impact the existence of a phase transition. In particular, pressure-induced phase transitions are suppressed after a certain absorbed dose threshold is reached for the sample. This is thought to be due to partial amorphization and/or defect formation in the sample, hindering the co-operative structural distortions needed for a phase transition. The high-pressure experiments were conducted with several crystals within the sample chamber in order to measure crystals with minimal X-ray irradiation at the highest pressures, which are compared with the crystals measured continuously upon pressure increase. Ways to minimize radiation damage are also discussed within the frame of high-pressure experiments.

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Radiotherapy (RT) is a key component of cancer treatment. Although improvements have been made over the years, radioresistance remains a challenge. For this reason, a better understanding of cell fates in response to RT could improve therapeutic options to enhance cell death and reduce adverse effects. Here, we showed that combining RT (photons and protons) to noncytotoxic concentration of PARP inhibitor, Olaparib, induced a cell line-dependent senescence-like phenotype. The senescent cells were characterized by morphological changes, an increase in p21 mRNA expression as well as an increase in senescence-associated ß-galactosidase activity. We demonstrated that these senescent cells could be specifically targeted by Navitoclax (ABT-263), a Bcl-2 family inhibitor. This senolytic drug led to significant cell death when combined with RT and Olaparib, while limited cytotoxicity was observed when used alone. These results demonstrate that a combination of RT with PARP inhibition and senolytics could be a promising therapeutic approach for cancer patients.