Cytogenetic studies for a group of people living in Japan 1 year after the Fukushima nuclear accident

Evaluation of DNA damage and stress in wildlife chronically exposed to low-dose, low-dose rate radiation from the Fukushima Dai-ichi Nuclear Power Plant accident

The health effects associated with chronic low-dose, low-dose rate (LD-LDR) exposures to environmental radiation are uncertain. All dose-effect studies conducted outside controlled laboratory conditions are challenged by inherent complexities of ecological systems and difficulties quantifying dose to free-ranging organisms in natural environments. Consequently, the effects of chronic LD-LDR radiation exposures on wildlife health remain poorly understood and much debated. Here, samples from wild boar (Sus scrofa leucomystax) and rat snakes (Elaphe spp.) were collected between 2016 and 2018 across a gradient of radiation exposures in Fukushima, Japan. In vivo biomarkers of DNA damage and stress were evaluated as a function of multiple measurements of radiation dose. Specifically, we assessed frequencies of dicentric chromosomes (Telomere-Centromere Fluorescence in situ Hybridization: TC-FISH), telomere length (Telo-FISH, qPCR), and cortisol hormone levels (Enzyme Immunoassay: EIA) in wild boar, and telomere length (qPCR) in snakes. These biological parameters were then correlated to robust calculations of radiation dose rate at the time of capture and plausible upper bound lifetime dose, both of which incorporated internal and external dose. No significant relationships were observed between dicentric chromosome frequencies or telomere length and dose rate at capture or lifetime dose (p value range: 0.20-0.97). Radiation exposure significantly associated only with cortisol, where lower concentrations were associated with higher dose rates (r² = 0.58; p < 0.0001), a relationship that was likely due to other (unmeasured) factors. Our results suggest that wild boar and snakes chronically exposed to LD-LDR radiation sufficient to prohibit human occupancy were not experiencing significant adverse health effects as assessed by biomarkers of DNA damage and stress.

A Biomarker Panel of Radiation-Upregulated miRNA as Signature for Ionizing Radiation Exposure

Ionizing radiation causes serious injury to the human body and has long-time impacts on health. It is important to find optimal biomarkers for the early quick screening of exposed individuals. A series of miRNAs signatures have been developed as the new biomarkers for diagnosis, survival, and prognostic prediction of cancers. Here, we have identified the ionizing radiation-inducible miRNAs profile through microarray analysis. The biological functions were predicted for the top six upregulated miRNAs by 4 Gy γ-rays: miR-1246, miR-1307-3p, miR-3197, miR-4267, miR-5096 and miR-7641. The miRNA-gene network and target gene-pathway network analyses revealed that DNAH3 is the target gene associated with all the six miRNAs. GOLGB1 is related to 4 miRNAs and other 26 genes targeted by 3 miRNAs. The upregulation of fifteen miRNAs were further verified at 4 h and 24 h after 0 to 10 Gy irradiation in the human lymphoblastoid AHH-1 cells, and some demonstrated a dose-dependent increased. Six miRNAs, including miR-145, miR-663, miR-1273g-3p, miR-6090, miR-6727-5p and miR-7641, were validated to be dose-dependently upregulated at 4 h or 24 h post-irradiation in both AHH-1 and human peripheral blood lymphocytes irradiated ex vivo. This six-miRNA signature displays the superiority as a radiation biomarker for the translational application of screening and assessment of radiation exposed individuals.

Radioactively contaminated areas: Bioindicator species and biomarkers of effect in an early warning scheme for a preliminary risk assessment

Concerns about the impacts on public health and on the natural environment have been raised regarding the full range of operational activities related to uranium mining and the rest of the nuclear fuel cycle (including nuclear accidents), nuclear tests and depleted uranium from military ammunitions. However, the environmental impacts of such activities, as well as their ecotoxicological/toxicological profile, are still poorly studied. Herein, it is discussed if organisms can be used as bioindicators of human health effects, posed by lifetime exposure to radioactively contaminated areas. To do so, information was gathered from several studies performed on vertebrates, invertebrate species and humans, living in these contaminated areas. The retrieved information was compared, to determine which are the most used bioindicators and biomarkers and also the similarities between human and non-human biota responses. The data evaluated are used to support the proposal for an early warning scheme, based on bioindicator species and on the most sensitive and commonly shared biomarkers, to perform a screening evaluation of radioactively contaminated sites. This scheme could be used to support decision-making for a deeper evaluation of risks to human health, making it possible to screen a large number of areas, without disturbing and alarming local populations.

Utilization of cytogenetic biomarkers as a tool for assessment of radiation injury and evaluation of radiomodulatory effects of various medicinal plants - a review

Systematic biological measurement of “cytogenetic endpoints” has helped phenomenally in assessment of risks associated with radiation exposure. There has been a surge in recent times for the usage of radioactive materials in health care, agriculture, industrial, and nuclear power sectors. The likelihood of radiation exposure from accidental or occupational means is always higher in an overburdened ecosystem that is continuously challenged to meet the population demands. Risks associated with radiation exposure in this era of modern industrial growth are minimal as international regulations for maintaining the safety standards are stringent and strictly adhered to, however, a recent disaster like “Fukushima” impels us to think beyond. The major objective of radiobiology is the development of an orally effective radio-modifier that provides protection from radiation exposure. Once available for mass usage, these compounds will not only be useful for providing selective protection against accidental and occupational radiation exposure but also help to permit use of higher doses of radiation during treatment of various malignancies curtailing unwarranted adverse effects imposed on normal tissues. Bio-active compounds isolated from natural sources enriched with antioxidants possess unique immune-modulating properties, thus providing a double edged benefit over synthetic radioprotectors. We aim to provide here a comprehensive overview of the various agents originating from plant sources that portrayed promising radioprotection in various experimental models with special emphasis on studies that used cytogenetic biomarkers. The agents will include crude extracts of various medicinal plants, purified fractions, and herbal preparations.

Chromosomal instability--mechanisms and consequences

Chromosomal instability is defined as a state of numerical and/or structural chromosomal anomalies in cells. Numerous studies have documented the incidence of chromosomal instability, which acutely or chronically may lead to accelerated ageing (tissue-wide or even organismal), cancer or other genetic disorders. Potential mechanisms leading to the generation of chromosome-genome instability include erroneous/inefficient DNA repair, chromosome segregation defects, spindle assembly defects, DNA replication stress, telomere shortening/dysfunction - to name a few. Understanding the cellular and molecular mechanisms for chromosomal instability in various human cells and tissues will be useful in elucidating the cause for many age associated diseases including cancer. This approach holds a great promise for the cytogenetic assays not only for prognosis but also for diagnostic purposes in clinical settings. In this review, a multi-dimensional approach has been attempted to portray the complexity behind the incidence of chromosome-genome instability including evolutionary implications at the species level for some of the mechanisms of chromosomal instability.

Correlation between radiation dose and p53 protein expression levels in human lymphocytes

The aim of this research was to evaluate the relationship between p53 protein levels and absorbed doses from in vitro irradiated human lymphocytes. For this, samples of blood from 23 donors were irradiated with 0.5; 1; 2; and 4 Gy from a Cobalt-60 source, and the percentages of lymphocytes expressing p53 were scored using Flow Cytometry. The subjects were divided into 3 groups, in accordance with the p53 levels expressed per radiation dose: low (Group I), high (Group II), and excessive levels (Group III). For all groups, the analyses showed that the p53 expression levels increase with the absorbed dose. Particularly for groups I and II, the correlation between this protein expression and the dose follows the linear-quadratic model, such as for radioinduced chromosomal aberrations. In conclusion, our findings indicate possible applications of this approach in evaluating individual radiosensitivity prior to radiotherapeutical procedures as well as in medical surveillance of occupationally exposed workers. Furthermore, due to the rapidity of flow-cytometric analyses, the methodology here employed would play an important role in emergency responses to a large-scale radiation incident where many people may have been exposed.