International journal of radiation biology最新文献

Background: Radiotherapy is a widely used treatment method in oncology, applied by delivering high-energy particles or waves to the tumor tissue. Although tumor cells are targeted with radiotherapy, it can cause acute or long-term damage to healthy tissues. Therefore, the preservation of healthy tissues has been an important subject of various scientific researches. Melatonin has been shown to have a radioprotective effect on many tissues and organs such as liver, parotid gland, brain, and testicles. This study aimed to evaluate the protective effect of melatonin against the radiation at various doses and rates administered to the lung tissue of healthy mice.

Methods: This study was a randomized case-control study conducted with 80 rats comprising 10 groups with eight animals per group. Of the 10 groups, first is the control group, which is not given any melatonin, and second is the group that does not receive RT, which is given only melatonin, and the other eight groups are RT groups, four with melatonin and four without melatonin.

Results: There was no statistical difference in terms of histopathological findings in the lung tissue between the second group, which did not receive radiotherapy and received only melatonin, and the control group. Lung damage due to radiotherapy was statistically significantly higher in the groups that did not receive melatonin compared to the groups that received melatonin.

Conclusions: This study revealed that melatonin has a protective effect against the cytotoxic damage of RT in rats receiving RT.

Purpose: In cases of radiological or nuclear events, biological dosimetry enables decisions whether an individual was exposed to ionizing radiation and the estimation of the dose. Several statistical methods are used to assess uncertainties. The stringency of the applied method has an impact on the lowest dose that can be detected. To obtain reliable and comparable results, it is crucial to harmonize the applied statistical methods.

Materials and methods: The decision threshold and detection limit of the statistical methods were derived for variable cell numbers. The coverage of the 95% confidence intervals as well as the false-positive and false-negative rates of the methods were compared based on simulations. The evaluated methods included a graphical method, the propagation of errors and a Bayesian method.

Results: The minimum resolvable doses, the doses at the detection limit and the coverage were relatively variable between the compared methods. The Bayesian method showed the best coverage, lowest resolvable doses and had false-positive rates close to 5%. The graphical method with the combination of two 83% confidence intervals also showed promising results. The other methods were either too conservative or underestimated the uncertainties for some doses or cell numbers.

Conclusions: The assessment of the lower dose limits is a central part of biological dosimetry and the applied statistical methods have a strong influence on the interpretation of the results. Simulations enable comparisons between methods and provide important information for the harmonization and standardization of the uncertainty assessment.

Background: Resistance to chemo- and radiotherapy is the main obstacle in cancer treatment success, which results in cancer's poor prognosis. Therefore finding the exact mechanism of resistance may contribute to addressing this concern. This could result in improved cancer prognosis and survival outcomes for cancer patients by targeting the basic causes of resistance.

Aim: This systematic review and meta-analysis assessed the potential of using autophagy-related proteins as prognostic biomarkers in radiotherapy-treated patients.

Methods: Following PRISMA guidelines, we systematically reviewed 956 studies from PubMed, Scopus, and Web of Science databases until April 2023. The keywords used for this purpose were 'cancer', 'radiotherapy', 'prognosis', and 'Autophagy'. Then the related meta-analysis was performed using STATA software.

Results: Four studies met the inclusion criteria. Upregulation of autophagy markers (LC3B, Beclin1 and ULK1) and subsequent activation of autophagy were significantly associated with a higher risk of mortality (1.95 times) in radiotherapy-treated groups compared with patients with low expression of these markers. Although such results were observed for recurrence-free survival (RFS); however, it was not significant.

Conclusion: The findings of this meta-analysis suggest that autophagy activation may be a critical factor in resistance to radiotherapy and subsequent poor survival rates in cancer patients. Consequently, assessing the expression of autophagy-related markers like Beclin1, LC3II, P62, and ULK may be a useful method for monitoring cancer prognosis following radiotherapy.

Purpose: To estimate diffusion tensor imaging (DTI) parameters for early diagnosis during the stage of radiation-induced brain injury (RBI) in nasopharyngeal carcinoma (NPC) patients.PubMed, Embase, Web of Science and Cochrane Library were searched up to March 2019. Eligible studies comparing early brain injuries with controls of temporal lobe in NPC patients before and after radiotherapy which collected the DTI parameters such as apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusibility (λa), radial diffusibility (λr), mean diffusion (MD) were included.

Conclusion: Seven studies (N = 21) were selected from the studies in the databases. Overall, FA, λa, λr values were significant difference between early RBI and healthy control (HC) in NPC patients after radiotherapy (MD= -0.03, 95% CI= -0.05∼-0.01; p = .008 in FA, MD= -0.07, 95% CI= -0.11∼-0.02; p = .002 in λa and MD = 0.02, 95% CI = 0.00 ∼ 0.04; p = .04 in λr). The meta regression analysis about dose dependence with FA value was: -0.057 ∼ 0.0003 in 95% CI, I²=74.70%, P = 0.052 (adjust p = .029). The overall heterogeneity is p < .001, I²=91% in FA, P = 0.08, I²=61% in λa and p = .04, I²=69% in λr. DTI parameters such as the reduced FA value, the decreased λa value, and the increased λr value were significant in the early period of RBI in NPC patients after radiotherapy, which becoming a more sensitive method in diagnosing the early stage of RBI.

Purpose: Epidemiological studies of stochastic radiation health effects such as cancer, meant to estimate risks of the adverse effects as a function of radiation dose, depend largely on estimates of the radiation doses received by the exposed group under study. Those estimates are based on dosimetry that always has uncertainty, which often can be quite substantial. Studies that do not incorporate statistical methods to correct for dosimetric uncertainty may produce biased estimates of risk and incorrect confidence bounds on those estimates. This paper reviews commonly used statistical methods to correct radiation risk regressions for dosimetric uncertainty, with emphasis on some newer methods. We begin by describing the types of dose uncertainty that may occur, including those in which an uncertain value is shared by part or all of a cohort, and then demonstrate how these sources of uncertainty arise in radiation dosimetry. We briefly describe the effects of different types of dosimetric uncertainty on risk estimates, followed by a description of each method of adjusting for the uncertainty.

Conclusions: Each of the method has strengths and weaknesses, and some methods have limited applicability. We describe the types of uncertainty to which each method can be applied and its pros and cons. Finally, we provide summary recommendations and touch briefly on suggestions for further research.

Purpose: The genus Mentha spp. is an aromatic herb from the family 'Lamiaceae'. It is extensively predominant in temperate and sub-temperate regions of the world. The essential oil of this species is enriched with broad aroma constituents extensively utilized in food, beverages, flavor, cosmetics, perfumery, and pharmaceutical enterprises. With the global menthol market size estimated to be worth USD 765 million in 2022, India (accompanied by China and Brazil) is the world's primary manufacturer, consumer, and exporter of Mentha oil. Despite prominent global demand, the crucial bottleneck in mint cultivation is the need for more superior commercial cultivars. Predominant vegetative propagation mode with difficulties in manual emasculation, differential blooming times, sterile/sub-sterile hybrids, and low seed viability are the primary containment in creating genetic variability by classical breeding approaches. Therefore, genetic complications encountered in conventional breeding have led the breeders to apply mutation breeding as an alternative crop improvement approach in Mentha spp. These attempts at mutation breeding have produced some distinctive mutants as genetic pools for plant breeding programs, and some novel mutant mint cultivars have been made available for commercial cultivation.

Conclusions: The prime strategy in mutation-based breeding has proven an adept means of encouraging the expression of recessive genes and producing new genetic variations. The present review comprises a significant contribution of mutation breeding approaches in the development of mutant mint species and its effects on physiological variation, photosynthetic pigment, essential oil content and composition, phytochemical-mediated defense response, pathogen resistivity, and differential expression of genes related to terpenoid biogenesis. Development and diversification have led to the release of varieties, namely Todd's Mitcham, Murray Mitcham, Pranjal, Tushar, and Kukrail in M. piperita L., Mukta, and Pratik in M. cardiaca Baker, Neera in M. spicata L., Kiran in M. citrata Ehrh., and Rose mint in M. arvensis L. that have revolutionized and uplifted mint cultivation leading to economic gain by the farmers and entrepreneurs.

Purpose: Risk analyses, based on relative biological effectiveness (RBE) estimates for neutrons relative to gammas, were performed; and the change in the curvature of the risk to dose response with increasing neutron RBE was analyzed using all solid cancer mortality data from the Radiation Effect Research Foundation (RERF). Results were compared to those based on incidence data.

Materials and methods: This analysis is based on RERF mortality data with separate neutron and gamma doses for colon doses, from which organ averaged doses could be calculated. A model for risk ratio variation with RBE was developed.

Results: The best estimate of the neutron RBE considering mortality data was 200 (95% confidence interval (CI): 50-1010) for colon dose using the weighted-dose approach and for organ averaged dose 110 (95% CI: 30-350). The ERR risk ratios for all solid cancers combined, for the best fitting neutron RBE estimate and the neutron RBE of 10 result in a ratio of 0.54 (95% CI: 0.17-0.85) for colon dose and 0.55 (95% CI: 0.18-0.87) for organ averaged dose. The risk to dose response curvature became significantly negative (concave down) with increasing RBE, at a neutron RBE of 170 using colon dose and at an RBE of 90 using organ averaged dose for males when fitting a linear-quadratic dose response. For females, the curvature decreased toward linearity with increasing neutron RBE and remained significantly positive until RBE of 80 and 40 using colon and organ averaged dose, respectively. For higher neutron RBEs, no significant conclusion could be drawn about the shape of the dose-response curve.

Conclusions: Application of neutron RBE values higher than 10 results in substantially reduced cancer mortality risk estimates and a significant reduction in curvature of the risk to dose responses for males. Using mortality data, the best fitting neutron RBE is much higher than when incidence data is used. The neutron RBE ranges covered by the overlap in the CIs from both the mortality and incidence analyses are 50-190 using colon dose and in all cases, the best fitting neutron RBE and lower 95% CI are higher than the value of 10 traditionally applied by the RERF. Therefore, it is recommended to consider uncertainties in neutron RBE values when calculating radiation risks and discussing the shape of dose responses using Japanese A-bomb survivors data.

Purpose: Radiation mutagenesis, which typically involves gamma rays, is important for generating new rice germplasm resources. Determining the appropriate radiation dose range is critical for the success of radiation mutagenesis. Clarifying the sensitivity and tolerance of genotypically diverse rice varieties to gamma irradiation as well as the radiation-induced changes to reactive oxygen species (ROS) generation and antioxidant enzyme activities is crucial for increasing the utility of radiation mutagenesis in rice breeding programs.

Materials and methods: The seeds of the following four rice varieties with different genotypes were used as test materials: indica Zhe 1613, glutinous indica Zhe 1708, japonica Zhejing 100, and glutinous japonica Zhenuo 65. Additionally,⁶⁰Co was used as the source of gamma rays. The rice seeds were irradiated with 14 doses (0, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, and 750 Gy). Non-irradiated seeds were used as the control. The seedling survival rate for each variety was recorded at 3, 7, 14, and 28 days after sowing. Moreover, the median lethal dose (LD₅₀) and critical dose (LD₄₀) were calculated according to the seedling survival rates at 28 days after sowing. The seedling superoxide anion (O₂^•-), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) contents and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities were analyzed at 7 days after sowing.

Results: As the radiation dose increased, the seedling survival rate decreased. The seedling survival rate also decreased significantly as the number of days after sowing increased. Among the rice genotypes, the rank-order of the radiation tolerance was as follows: indica Zhe 1613 > glutinous indica Zhe 1708 > japonica Zhejing 100 > glutinous japonica Zhenuo 65. The LD₅₀ values were 426.7 Gy for Zhe 1613, 329.2 Gy for Zhe 1708, 318.3 Gy for Zhejing 100, and 316.6 Gy for Zhenuo 65. Increases in the radiation dose resulted in significant increases in the seedling O₂^•- and H₂O₂ contents, but only up to a certain point. Further increases in the radiation dose caused the seedling O₂^•- and H₂O₂ contents to decrease. The H₂O₂ content for each variety peaked when the radiation dose was very close to the LD₅₀. We propose that the radiation dose associated with the highest H₂O₂ content (±50 Gy) should be used as the recommended dose for the gamma irradiation of rice. The radiation dose that resulted in peak seedling O₂^•- contents in the analyzed rice varieties was very close to the LD₄₀. In all rice varieties, the MDA conten