Radiation Medicine and Protection最新文献

Objective

To investigate the mechanism of p53-induced gene 3 (PIG3)-regulation of radioresistance in human non-small cell lung cancer (NSCLC) cells, in order to explore new biomarkers and therapeutic targets to combat radioresistance and improve the 5-year survival rate.

Methods

The PIG3 gene was knocked down in A549 ​cells using siRNA, and was overexpressed in H1299 ​cells using a PIG3 expression plasmid. After confirming PIG3 knockdown and overexpression through the Western blot analysis, the radiosensitivity, DNA damage, cell cycle distribution, and apoptosis in these cells were analyzed using colony formation assay, immunofluorescence staining for γH2AX, and flow cytometry, respectively.

Results

PIG3 silencing markedly increased the radiosensitivity of NSCLC cells, with radiosensitization ratios of 1.12 and 1.25. Compared with the corresponding negative control, PIG3 knockdown significantly enhanced G₂/M phase arrest (siNC: 26.12 ​± ​2.50, siPIG3#1: 34.98 ​± ​4.19, siPIG3#2: 37.79 ​± ​3.53, P ​< ​0.05), promoted radiation-induced apoptosis (siNC: 14.61 ​± ​1.85, siPIG3#1: 17.26 ​± ​1.14, siPIG3#2: 20.70 ​± ​2.04, P ​< ​0.05), and reduced the number of γ-H2AX foci 0.5, 1, and 2 ​h after radiation (P ​< ​0.05). Conversely, PIG3 overexpression markedly decreased the radiosensitivity of NSCLC cells, as evidenced by the reduction of G₂/M phase arrest (NC: 33.18 ​± ​2.11 vs. PIG3: 24.21 ​± ​3.09, P ​< ​0.05) and apoptosis (NC: 15.49 ​± ​0.56 vs. PIG3: 12.79 ​± ​0.29, P ​< ​0.05), and increased DNA damage (P ​< ​0.05).

Conclusions

PIG3 downregulation increases the radiosensitivity of NSCLC cells, and PIG3-upregulation leads to the progression in radioresistance. Therefore, PIG3 is a potential target for radiotherapy for NSCLC.

Objective

To assess the risk of lens opacity depending on the dose in the population exposed to external and internal radiation for a long time, based on a long-term clinical follow-up of the cohorts of people exposed to radiation as a result of two radiation accidents in the South Urals.

Methods

A layer-by-layer morphological study of the lens of 1,377 exposed individuals was conducted according to a special program in the Clinical Department of the Urals Research Center for Radiation Medicine (URCRM) 68 years after the onset of exposure. Lens changes were classified in accordance with the lens opacities classification (LOCS) III and included images of lens. To calculate the doses to lens, the data were taken into account, including the person's residence history in the radioactively contaminated territory, age and sex that affected their lifestyle and diet, radionuclide distribution in organs and tissues. Individualized lens doses were calculated using Techa River Dosimetry System (TRDS)-2016. Case-control method was used for statistical analysis.

Results

Individual values of absorbed dose to lens ranged from 0 to 600 ​mGy. A dose-dependent increased risk of posterior subcapsular cataract (PSC) (OR ​1.54, 95%CI: 1.04–2.27) and nuclear cataract (OR ​1.84, 95%CI: 1.14–2.95) was found among chronically exposed individuals by a case-control method. No evidence of dose effect was found for cortical cataracts.

Conclusions

The results showed that population exposed to long-term chronic low-dose radiation was subjected to an increased risk of PSC and nuclear cataract development.

The paper presents the key milestones and outcomes of 65-year studies of the carcinogenic consequences of accidental radiation exposure of the population of the Ural region. The radioactive contamination of the Techa River and the 1957 accident at the Mayak Production Association were the reasons of the long-term population exposure at a wide dose-range. The most important tasks of the study were the reconstruction of individual doses, follow-up of the solid cancer and leukemia incidence and mortality among cohort members. The research results have shown that chronic human exposure, in comparison to acute exposure, does not reduce the risk of developing malignant tumors and leukemias. The value of the dose-rate factor does not exceed "one".

Thus, according to our data, the Publication 103 of the International Commission on Radiological Protection seemed to underestimate the radiation risk of malignant tumors and leukemias in case of low dose-rate exposure of the population by a factor of two. Prospects for further radio-epidemiological studies in the Urals are associated with the analysis of the cohort of Southern Urals Populations Exposed to Radiation, which includes about 63 thousand exposed people and makes it possible to assess the radiation risk of solid cancers of certain localizations, certain types of leukemia, and non-cancer effects.

Nomograms have been increasingly adopted in cancer studies for predicting a variety of clinical outcomes. Compared to conventional prediction approaches, nomograms present an excellent graphical easy-to-interpret visualization and by combining patients’ characteristics and statistical models constructed based on diagnostic tests, higher accuracy could be achieved, facilitating the clinical decision-making process. However, with the increasing number of nomograms being proposed, misinterpretations may often occur, introducing a large degree of uncertainties in clinical situations. This review article aims to provide a methodological summary for nomogram applications, construction, and interpretation, with a demonstrative example of nasopharyngeal carcinoma patient data in the field of radiation medicine. Common misunderstandings and limitations are also discussed to underscore the applicability of nomograms in different scenarios. The overarching goal of this review article is to provide general audiences with fundamental and essential knowledge toward comprehending and implementing nomograms in cancer studies.

Hepatocellular carcinoma (HCC), one of the deadliest cancers all over the world, had a limited prognosis in the past. Recently, the remarkable efficacy of immune checkpoint inhibitors (ICIs) therapy has been shown in various solid tumors. What's more, the occurrence of HCC is associated with immune escape and therefore various ICIs have been applied to clinical trials for HCC. However, the special immune environment of the liver creates the complex tumor microenvironment (TME) of HCC, which impairs the overall survival (OS) and overall response rate (OCR) of ICIs as a monotherapy. Lately, various therapies have been used in combination with ICIs therapy to improve its clinical efficacy. Among which, radiotherapy is widely concerned because of its unique immunoreaction. A large number of basic and clinical studies have demonstrated that the combined radiotherapy and ICIs therapy has advantages in improving the OCR and efficacy, as compared with ICIs therapy alone. Herein, this article reviews the studies on the advantages and possible mechanisms of the combination of radiotherapy and ICIs therapy for HCC.

Glioma has received considerable attention because of its potential of inducing high rates of morbidity, disability, and mortality. FLASH radiotherapy (FLASH-RT) has emerged as a popular topic in current research because of its ability to protect normal tissues. The present review summarized the current development of FLASH-RT in both the central nervous system and glioblastomas, explored the potential mechanisms underlying FLASH-RT-mediated protective effects on the central nervous system, and revealed the advantages of this new technique for glioma therapy. This study highlights the benefits and challenges of the present research and provides a reference for future research.

Objective

To investigate the specific activities of gamma radionuclides in the soils around high energy accelerators, and to analyze the influence of rays emitted by nuclides with characteristic peaks at similar energy points on nuclide measurement results, in order to provide reference for the accurate identification of radionuclides.

Methods

GR5021 high-purity germanium gamma spectroscopy system was used to measure the specific activities of gamma-emitting radionuclides ²²⁶Ra, ²³²Th, ²³⁸U, ⁴⁰K and artificial radionuclides ⁵⁴Mn, ⁵²Mn, ⁷Be, ²²Na, ⁵⁹Fe, ⁹⁵Zr in six soil samples around three kinds of high energy accelerators, and the theoretical counts of the characteristic peak of 835.7 ​keV were compared with the measured counts of the characteristic peak of ⁵⁴Mn.

Results

The specific activity ranges of gamma-emitting radionuclides ²²⁶Ra, ²³²Th, ²³⁸U and ⁴⁰K in the soils around three kinds of high energy accelerators were 55.5–171, 34.9–99.9, 21.9–79.3 and 247–680 Bq/kg, respectively. The specific activities of artificial radionuclides ⁵²Mn, ⁷Be, ²²Na, ⁵⁹Fe and ⁹⁵Zr were basically lower than the minimum detection limit. A characteristic peak was found at the energy point of 835.7 ​keV in six soil samples, and the corresponding total absorption peak counts were from ²²⁸Ac of ²³²Th ​decay daughter.

Conclusions

The specific activities of gamma-emitting radionuclides were at the normal natural background levels. The specific activities of artificial radionuclides were basically lower than the minimum detection limits. For ²³²Th, when its specific activity is above 40 Bq/kg, characteristic peak of its decay daughter ²²⁸Ac could be misjudged as characteristic peak of ⁵⁴Mn.

This paper gives a detailed description of a radiological accident of ¹⁹²Ir source occurring on May 7, 2014 in Nanjing, China (the 5⋅7 accident), encompassing a combination of accident overview, emergency response, investigation process and results, dose estimation, medical treatment, experience and lessons learnt. The investigation showed that the accident was mainly caused by insufficient attention to the radiation safety, non-compliance with licensing conditions and employment of untrained temporary radiographer without equipped with alarm dosimeters. Additionally, no area radiation survey meter was used to verify whether the source would have retracted to radiography camera after every exposure. It therefore is the important means to strengthen the management of radioactive source safety and put the strict management measures in place, implement the requirements for personnel qualification management, strengthen regulatory inspection and actively poster safety culture, which are necessary to avoid accidents. This paper aims to provide experience and reference for the emergency response and countermeasure of radiological accidents involving industrial radioactive sources.

Objective

To evaluate the low melting-point MCP-69, MCP-96, MCP-137, and MCP-200 alloys, and characterize them for their potential to protect from the harms associated with radiation and eliminate radiation hazards during radiological procedures and treatment of cancer.

Methods

The Klein-Nishina formula was used to calculate the electronic and atomic cross-sections of these alloys using photon beams with energies 4, 6, 9, 12, and 18 ​MeV. Energy transfer coefficients, Compton mass attenuation coefficient, mass-energy transfer coefficient, and recoil energy of electrons in the specific photon energies of 4–18 ​MeV were calculated. The alloys' effective charge number and the photon energy were key factors in determining the properties found by utilizing the Klein-Nishina formula and Compton effects.

Results

The cross sections and energy transfer coefficients increased with the increasing effective charge number Z of the alloys and decreased as the photon energy increased. The Compton recoil of the ejected electrons was observed to have a direct relationship with photon energy, but mass-energy transfer decreased with increasing photon energy. These alloys can replace the toxic lead for environmentally cleaned radiation applications.

Conclusions

These calculations and characteristics of the MCP alloys can help further determine their viability as materials for radiation shielding, their use in safe cancer diagnosis, treatment, and environmental hazards protection.

Nuclear safety is a major concern given the rapid development of nuclear power in the modern era. Fostering a nuclear safety culture is an important means of ensuring nuclear safety. In China, a country with a rich historical and cultural heritage, traditional culture will influence the development of a nuclear safety culture. This study explored the origin and levels of nuclear safety culture and reflected on nuclear safety culture from the perspective of traditional Chinese culture. The purpose of this study is to integrate the essence of traditional culture into the nuclear safety culture and foster a nuclear safety culture with Chinese characteristics.