International Journal of Radiation Biology最新文献

Purpose: To identify the bonding sites of initial radiation interaction with DNA and to trace the following chemical reaction sequences on the pathway of damage induction, we carry out a spectroscopy XIL (X-ray induced luminescence) using soft X-ray synchrotron radiation. This is a nondestructive analysis of the excited intermediate species produced in a molecular mechanism on the damage induction pathway.

Materials and methods: We introduce aqueous samples of UMP (uridine-5'-monophosphate) in the vacuum by the use of a liquid micro-jet technique. The luminescence in the region of UV-VIS (from visible to ultraviolet) radiation induced after the absorption of monochromatic soft X-ray by aqueous UMP is measured with sweeping the soft X-ray energy in the region of 370-560 eV.

Results: The enhanced XIL intensities for aqueous UMP in the region of soft X-ray of 410-530 eV (in "water window" region) are obtained. The enhancement of XIL intensities in the UV-VIS region, relative to the water control, is explained by the excitation and ionization of a K-shell electron of nitrogen atoms in the uracil moiety. The enhanced XIL intensities do not match the structure of XANES (X-ray absorption near-edge structure) of the aqueous UMP. This suggests that the XIL intensities reflect the quantum yields of luminescence, or the quantum yields for conversion by UMP of an absorbed X-ray into UV-VIS radiation. In this paper, spectra of luminescence are shown to be resolved by combining low pass filters. The filtered luminescence spectra are obtained at the center of gravity (λc) of the band pass wavelength regions at λc = 270nm, 295 nm, 340 nm, 385 nm, 450 nm, and 525 nm., which show a trend similar to the fluorescence of nucleobases induced by ultraviolet radiation.

Conclusion: It is concluded that the origin of the observed XIL is the hydrated uracil moiety in aqueous UMP, decomposition of which is suppressed by the migration of excess charge and internal energy after the double ionization due to Auger decay.

Purpose: The study of the radioactive role of natural and chemical substances on human and animal studies has been the subject of research by some researchers. Therefore, the review of some of the past and current studies conducted in this field, can provide helpful information to elucidate of the importance of radioprotective components in reducing radiation exposure side effects.

Methods: The authors search for keywords including In vitro, In vivo, Radioprotective, Ionizing radiation, and Vitamin in ScienceDirect, Scopus, Pubmed, and Google Scholar databases to access previously published articles and search for more reference articles on the role of radioprotective materials from natural and chemical compounds.

Results: Radiation exposure can produce reactive oxygen species (ROS) in the body, however most of which are eliminated by the body's natural mechanisms, but when the body's antioxidant systems do not have enough ability to neutralize free radicals, oxidative stress occurs, which causes damage to DNA and body tissues. Therefore, it is necessary use of alternative substances that reduce and inhibit free radicals.

Conclusion: In general, recommended that antioxidant component(s) can be protect tissue damages in humans or animals, due to the their ability to scavenge free radicals generated by ionizing radiation.

Purpose: Monochromatic hard X-rays with high brightness are desired for medical applications including Auger therapy. One can generate such X-rays through laser-Compton scattering (LCS) by allowing photons from a compact laser system to interact with electrons accelerated by a compact electron accelerator. In this paper, after a brief description of laser-Compton X-ray sources, a scheme called crab crossing to enhance the X-ray intensity is proposed. The effect of crab crossing is evaluated, and we report our dedicated laser system for the crab crossing LCS research.

Materials and methods: The luminosity enhancement factor by crab crossing is evaluated. For the electron beam, a rf deflector will be used to generate a tilted electron beam. For the laser system, chirped pulsed amplification is adopted. Yb-doped optical fibers and a Yb:YAG thin-disk is used for the laser gain media.

Results: The luminosity enhancement factor by crab crossing is expected to be 3.8 when the crossing angle is 45 degrees. 10mJ pulse energy was achieved by thin-disk regenerative amplifier. The pulse duration after the pulse compressor was about 1.5 ps.

Conclusion: We are going to demonstrate the LCS X-ray enhancement by crab crossing of electron beam and laser pulse. The expected enhancement factor is 3.8. We have successfully finished the laser development and the proof-of-principle experiment will be conducted soon.

Purpose: To investigate sources, accumulation, and vertical migration of radionuclides in Armenia, and their impact on biota.

Conclusions: This review describes the radiation status in the landscape of Armenia and features of the impact of natural and human-generated radiation on human and non-human biotas, according to studies of Armenian scientists carried out since the middle of the last century. The mountain landscape demonstrates the diversity, speciation, and radioresistance of the biota, which arise under radiation exposure in a variable environment. Although the effects of radiation have been described for a long time, some of them require further study. It is important to present the data collected in order to produce a base line for future studies of radiation effects and interactions with other stressors caused by climate change.

Purpose: This article summarizes a number of presentations from a session on "Radiation and Circulatory Effects" held during the Radiation Research Society Online 67^th Annual Meeting, October 3-6 2021.

Materials and methods: Different epidemiological cohorts were analyzed with various statistical means common in epidemiology. The cohorts included the one from the U.S. Million Person Study and the Canadian Fluoroscopy Cohort Study. In addition, one of the contributions in our article relies on results from analyses of the Japanese atomic bomb survivors, Russian emergency and recovery workers and cohorts of nuclear workers. The Canadian Fluoroscopy Cohort Study data were analyzed with a larger series of linear and nonlinear dose-response models in addition to the linear no-threshold (LNT) model.

Results and conclusions: The talks in this symposium showed that low/moderate acute doses at low/moderate dose rates can be associated with an increased risk of CVD, although some of the epidemiological results for occupational cohorts are equivocal. The usually only limited availability of information on well-known risk factors for circulatory disease (e.g. smoking, obesity, hypertension, diabetes, physical activity) is an important limiting factor that may bias any observed association between radiation exposure and detrimental health outcome, especially at low doses. Additional follow-up and careful dosimetric and outcome assessment are necessary and more epidemiological and experimental research is required. Obtaining reliable information on other risk factors is especially important.

Purpose: Head and neck squamous cell carcinoma (HNSCC) is a major cause of morbidity and mortality. Although HNSCC is mainly caused by tobacco and alcohol consumption, infection by Human Papilloma Virus (HPV) has been also associated with the increasing incidence of oropharyngeal squamous cell carcinomas (OPSCC) during the past decades. HPV-positive HNSCC is characterized by a higher radiosensitivity compared to HPV-negative tumor. While several clinical trials are evaluating de-escaladed radiation doses strategies in HPV-positive HNSCC, molecular mechanisms associated with relative radioresistance in HPV-negative HNSCC are still broadly unknown. Our goal was to review recently proposed biomarkers of radioresistance in this setting, which may be useful for stratifying tumor's patient according to predicted level of radioresistance.

Conclusions: most of biomarkers of radioresistance in HPV-negative HNSCC are identified using a hypothesis-driven approach, based on molecular mechanisms known to play a key role during carcinogenesis, compared to an unsupervised data-driven approach regardless the biological rational. DNA repair and hypoxia are the two most widely investigated biological and targetable pathways related to radioresistance in HNSCC. The better understanding of molecular mechanisms and biomarkers of radioresistance in HPV-negative HNSCC could help for the development of radiosensitization strategies, based on targetable biomarkers, in radioresistant tumors as well as de-escalation radiation dose strategies, based on biological level of radioresistance, in radiosensitive tumors.

Purpose: Wireless communication has become an integral part of our lives. The growing number of antennas in our environment and the expanding use of mobile phones (MPs) are increasing the population's exposure to electromagnetic fields. The present study aimed to examine the potential impact of MPs radiofrequency electromagnetic fields (RF-EMF) exposure on the brainwaves of the resting electroencephalogram (EEG) in humans.

Materials and methods: Twenty-one healthy volunteers were exposed to Global System for Mobile communications (GSM) signal at 900 MHz MP RF-EMF. The maximum specific absorption rate (SAR) of the MP averaged on 10 g tissue and 1 g tissue were measured at 0.49 W/kg, 0.70 W/kg, respectively.

Results: Results showed that while delta and beta rhythms of resting EEG were not affected, theta brainwaves were significantly modulated during exposure to RF-EMF related to MPs. For the first time, it was shown that this modulation is dependent on the eye condition, i.e. closed or open.

Conclusions: This study strongly suggests that acute exposure to RF-EMF alters the EEG theta rhythm at rest. Long-term exposure studies are required to explore the effect of this disruption in high-risk or sensitive populations.

Background: The most attractive features of Auger electrons (AEs) in cancer therapy are their extremely short range and sufficiently high linear energy transfer (LET) for a majority of them. The cytotoxic effects of AE emitters can be realized only in close vicinity to sensitive cellular targets and they are negligible if the emitters are located outside the cell. The nucleus is considered the compartment most sensitive to high LET particles. Therefore, the use of AE emitters could be most useful in specific recognition of a cancer cell and delivery of AE emitters into its nucleus.

Purpose: This review describes the studies aimed at developing effective anticancer agents for the delivery of AE emitters to the nuclei of target cancer cells. The use of peptide-based conjugates, nanoparticles, recombinant proteins, and other constructs for AE emitter targeted intranuclear delivery as well as their advantages and limitations are discussed.

Conclusion: Transport from the cytoplasm to the nucleus along with binding to the cancer cell is one of the key stages in the delivery of AE emitters; therefore, several constructs for exploitation of this transport have been developed. The transport is carried out through a nuclear pore complex (NPC) with the use of specific amino acid nuclear localization sequences (NLS) and carrier proteins named importins, which are located in the cytosol. Therefore, the effectiveness of NLS-containing delivery constructs designed to provide energy-dependent transport of AE emitter into the nuclei of cancer cells also depends on their efficient entry into the cytosol of the target cell.