Effect of external gamma-irradiation on the genetic apparatus of somatic cells of rat fetus

Cytogenetic effects of different radiation dose rate and dose value were studied in fibroblasts of 20-day old rat fetuses and new-born ratlings. Quantitative and qualitative changes in the occurrence frequency in the spectrum of chromosome aberration types were revealed and changes in aneuploid fibroblast ratio were observed. The damages in the fibroblast chromosome structure of fetuses remain after birth (2-day-old ratling) and they were also observed in fetuses of the second generation.     

Dynamics of Cellular Responses to Radiation

Understanding the consequences of exposure to low dose ionizing radiation is an important public health concern. While the risk of low dose radiation has been estimated by extrapolation from data at higher doses according to the linear non-threshold model, it has become clear that cellular responses can be very different at low compared to high radiation doses. Important phenomena in this respect include radioadaptive responses as well as low-dose hyper-radiosensitivity (HRS) and increased radioresistance (IRR). With radioadaptive responses, low dose exposure can protect against subsequent challenges, and two mechanisms have been suggested: an intracellular mechanism, inducing cellular changes as a result of the priming radiation, and induction of a protected state by inter-cellular communication. We use mathematical models to examine the effect of these mechanisms on cellular responses to low dose radiation. We find that the intracellular mechanism can account for the occurrence of radioadaptive responses. Interestingly, the same mechanism can also explain the existence of the HRS and IRR phenomena, and successfully describe experimentally observed dose-response relationships for a variety of cell types. This indicates that different, seemingly unrelated, low dose phenomena might be connected and driven by common core processes. With respect to the inter-cellular communication mechanism, we find that it can also account for the occurrence of radioadaptive responses, indicating redundancy in this respect. The model, however, also suggests that the communication mechanism can be vital for the long term survival of cell populations that are continuously exposed to relatively low levels of radiation, which cannot be achieved with the intracellular mechanism in our model. Experimental tests to address our model predictions are proposed.     

Effects of ultraviolet radiation and dissolved organic carbon on the survival of subarctic zooplankton

High intensities of ultraviolet radiation are known to be harmful to aquatic biota, especially for species living in shallow, clear water bodies. Zooplankton species from such habitats are good model organisms to study the effect of changes in UV radiation, and how animals deal with this. We tested experimentally the effect of natural UV radiation, which was controlled by different filters and varying concentrations of UV-screening dissolved organic carbon (DOC), on the survival of the cladocerans, Daphnia longispina and D. pulex, and a calanoid copepod, Eudiaptomus graciloides. All species originated from subarctic Fennoscandia where underwater UV intensity is influenced by ozone depletion, changes in DOC and timing of ice break-up. Measured as mortality, all species were affected by both UVB and UVA radiation. Survival was highest and similar between species in the dark controls and photosynthetically active radiation exposures. Under each UV filter, the highest DOC concentration provided significant and best shelter from UV radiation and led to best survival. Variation in survival was observed between species. E. graciloides responded more readily to changes in UV radiation than did the daphnids. In natural environments, species' previous exposure to light and different protection strategies (pigmentation, vertical migration) are probably as important factors controlling the survival of zooplankton as radiation intensity and optical properties of water.     

Parallel amino acid replacements in the rhodopsins of the rockfishes (Sebastes spp.) associated with shifts in habitat depth

Among various groups of fishes, a shift in peak wavelength sensitivity has been correlated with changes in their photic environments. The genus Sebastes is a radiation of marine fish species that inhabit a wide range of depths from intertidal to over 600 m. We examined 32 species of Sebastes for evidence of adaptive amino acid substitution at the rhodopsin gene. Fourteen amino acid positions were variable among these species. Maximum likelihood analyses identify several of these to be targets of positive selection. None of these correspond to previously identified critical amino acid sites, yet they may in fact be functionally important. The occurrence of independent parallel changes at certain amino acid positions reinforces this idea. Reconstruction of habitat depths of ancestral nodes in the phylogeny suggests that shallow habitats have been colonized independently in different lineages. The evolution of rhodopsin appears to be associated with changes in depth, with accelerated evolution in lineages that have had large changes in depth.     

Morphological abnormalities among the offspring of irradiated pines (pinus sylvestris L.) from chernobyl populations

The significant changes of the quantitative signs and the increase in the frequency of morphological abnormalities were found among the offspring of pines (Pinus sylvestris L.) exposed as a result of the Chernobyl accident. We have detected that the typical effects of radiation exposure (stimulation, inhibition, abnormalities of morphogenesis) are transmitted to the offspring of irradiated pine trees. The mechanisms of their occurrence are discussed.     

Spontaneous electrical activity of the rat cerebral cortex during microwave irradiation

A study was made of changes in spontaneous electrical activity of rat brain cortex induced by a single exposure to microwave radiation (electromagnetic fields of 0.1, 1.0, 10, and 35 mW/cm2). The animals were exposed in anechoic chambers to continuous waves at 2450 MHz in conditions of continuous generation. The data obtained indicate that the EEG parameters change under the effect of microwave radiation. The technique applied permits to study the occurrence and development of the CNS reactions to microwave radiation at the time of action of the factor.     

Comparative results of thyroid ultrasound and laboratory studies in patients exposed to radiation

The paper presents the data of thyroid ultrasound and laboratory studies in 233 persons exposed to radiation: 63 X-ray physicians, 36 Chernobyl accident liquidators, 31 patients with lymphogranulomatosis, receiving radiotherapy, and 103 individuals (a control group) who were physicians of various specialties whose professional activity is unassociated with radiation factors. Thyroid changes were found in 67.7% of the examinees after gamma teletherapy and in 31% in the control group; among X-rat physicians and Chernobyl accident liquidators, the occurrence of thyroid changes was equal--44.4%. Direct radiation exposure of the thyroid in a dose of above 30 Gy led to the development of postradiation fibrosis (22.5%) and postradiation thyroiditis (32.3%) with thyroid dysfunction that is most commonly presented by hypothyroidism (22.45%). Autoimmune thyroiditis (11.1%) more predominantly with subclinical hypothyroidism, and diffuse thyroid hyperplasia (19.4%) resulted from mixed internal and external radiation. Thyroid changes revealed in X-ray physicians mainly appeared as nodular masses (22.2%) without functional impairments but to be followed up. It is recommended that the annual preventive examination protocol be supplemented by thyroid ultrasound studies in X-ray physicians.     

Acute and late effects in the course of and after total body irradiation with following bone marrow transplantation in patients with different forms of leukaemia

The acute reaction in the course of a total body irradiation (TBI) appears in an organ-specific damage of the stem cells. Moreover, there are unspecified central-nervous stress reactions. Clinical reactions are obtained by the study and symptomatic therapy is proposed. 90 patients with different forms of leukaemia were observed. We documented the course in a specific "protocol system". Reactions like an increase of body temperature, changes of pulse and blood pressure were registered. The occurrence of gastro-intestinal reactions is a typical symptom of the acute radiation syndrome e.g. vomiting and diarrhoea are demonstrated in dependence of the applicated dose of irradiation. Further symptoms of TBI appeared in the later period. Mucositis, parotitis, a decreased function of the salivary glands and diarrhoea as well as vomiting are characterized by different intensity and temporary termination. A difference between allogeneic and autologous transplantation is caused by a medicamental additional treatment. During the late period these symptoms will disappear completely. Moreover, after TBI and BMT late effects are a cataract and some changes in the hormonal system demanding a specific correction or substitution respectively.     

NMR spectroscopy based metabolic profiling of urine and serum for investigation of physiological perturbations during radiation sickness

Radiation accidents are rare events that induce radiation syndrome, a complex pathology which is difficult to treat. In medical management of radiation victims, life threatening damage to different physiological systems should be taken into consideration. The present study was proposed to identify metabolic and physiological perturbations in biofluids of mice during different phases of radiation sickness using ¹H nuclear magnetic resonance (¹H NMR) spectroscopy and pattern recognition (PR) technique. The ¹H NMR spectra of the biofluids collected from mice irradiated with 5 Gray (Gy) at different time points during radiation sickness were analysed visually and by principal components analysis. Urine and serum spectral profile clearly showed altered metabolic profiles during different phases of radiation sickness. Increased concentration of urine metabolites viz. citrate, α ketoglutarate, succinate, hippurate, and trimethylamine during prodromal and clinical manifestation phase of radiation sickness shows altered gut microflora and energy metabolism. On the other hand, serum nuclear magnetic resonance (NMR) spectra reflected changes associated with lipid, energy and membrane metabolism during radiation sickness. The metabonomic time trajectory based on PR analysis of ¹H NMR spectra of urine illustrates clear separation of irradiated mice group at different time points from pre dose. The difference in NMR spectral profiles depicts the pathophysiological changes and metabolic disturbances observed during different phases of radiation sickness, that in turn, demonstrate involvement of multiple organ dysfunction. This could further be useful in development of multiparametric approach for better evaluation of radiation damage as well as for medical management during radiation sickness.     

Most common skin tumours in correlation with solar ultraviolet radiation in the area of West Herzegovina

Incidence rate of skin tumours, both, non-melanoma and melanoma, is increasing nowadays. Various etiological factors are of relevance for the occurrence of the diseases. The solar radiation, as well, long-term exposure to ultraviolet (UV) radiation, have the greatest impact on development of these skin tumours. Non-melanoma skin tumours, Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC), are the most common skin tumours in humans, and usually develop on the chronically photo-exposed areas. As for the Malignant Melanoma (MM), one of the most aggressive skin tumours, the exposure to solar radiation also plays an important role. This study investigates the correlation between the skin tumours and UV radiation in the area of West Herzegovina, on the sample of 1676 patients. It presents the occurrence of skin tumours in the period from 1997 to 2003. The study investigates the incidence and the risk factors separately for every skin tumour which can be etiologically related to the occurrence of skin tumours and UV radiation: occupation, exposure to UV radiation, skin type, and family history on malignan tumours within the patient's family. The exact incidence rate of non-melanoma and melanoma skin tumours in Bosnia and Herzegovina is still unknown, for the reason that the united National Cancer Register does not exist yet.     

Modelling the effects of changes in solar radiation on gross primary production in subtropical evergreen needle-leaf plantations

太阳辐射是陆地生态系统碳水循环的能量来源。太阳辐射的变化对植被吸收大气CO₂具有重要影响。该文通过辐射观测数据建立散射辐射比例与晴空指数的关系, 结合生态过程模型(BEPS)和通量观测数据, 模拟分析了太阳辐射变化对千烟洲常绿针叶林总初级生产力(GPP)的影响。研究结果表明: 千烟洲森林生态系统的阴叶对年GPP总量的贡献达67%, 太阳辐射变化对阴叶光合作用的影响决定了冠层GPP的变化; 太阳辐射强度和分布的年际差异导致年GPP对太阳辐射变化的响应不同, 2003、2004和2005年太阳辐射分别变化-5.44%、-1.83%和6.26%, 可使千烟洲生态系统当年GPP总量达到最大值; 在季节上, 太阳辐射的增加会导致5-6月GPP上升, 7-9月GPP下降, 使年GPP变化程度降低; 在天尺度上, 晴空指数在0.43时, 太阳辐射变化对GPP的影响最小。     

太阳辐射变化对亚热带人工常绿针叶林总初级生产力影响的模拟分析

太阳辐射是陆地生态系统碳水循环的能量来源。太阳辐射的变化对植被吸收大气CO₂具有重要影响。该文通过辐射观测数据建立散射辐射比例与晴空指数的关系, 结合生态过程模型(BEPS)和通量观测数据, 模拟分析了太阳辐射变化对千烟洲常绿针叶林总初级生产力(GPP)的影响。研究结果表明: 千烟洲森林生态系统的阴叶对年GPP总量的贡献达67%, 太阳辐射变化对阴叶光合作用的影响决定了冠层GPP的变化; 太阳辐射强度和分布的年际差异导致年GPP对太阳辐射变化的响应不同, 2003、2004和2005年太阳辐射分别变化-5.44%、-1.83%和6.26%, 可使千烟洲生态系统当年GPP总量达到最大值; 在季节上, 太阳辐射的增加会导致5-6月GPP上升, 7-9月GPP下降, 使年GPP变化程度降低; 在天尺度上, 晴空指数在0.43时, 太阳辐射变化对GPP的影响最小。     

Overview of the principles and practice of biodosimetry

The principle of biodosimetry is to utilize changes induced in the individual by ionizing radiation to estimate the dose and, if possible, to predict or reflect the clinically relevant response, i.e., the biological consequences of the dose. Ideally, the changes should be specific for ionizing radiation, and the response should be unaffected by prior medical or physiological variations among subjects, including changes that might be caused by the stress and trauma from a radiation event. There are two basic types of biodosimetry with different and often complementary characteristics: those based on changes in biological parameters such as gene activation or chromosomal abnormalities and those based on physical changes in tissues (detected by techniques such as EPR). In this paper, we consider the applicability of the various techniques for different scenarios: small- and large-scale exposures to levels of radiation that could lead to the acute radiation syndrome and exposures with lower doses that do not need immediate care, but should be followed for evidence of long-term consequences. The development of biodosimetry has been especially stimulated by the needs after a large-scale event where it is essential to have a means to identify those individuals who would benefit from being brought into the medical care system. Analyses of the conventional methods officially recommended for responding to such events indicate that these methods are unlikely to achieve the results needed for timely triage of thousands of victims. Emerging biodosimetric methods can fill this critically important gap.     

MiR-21 is continually elevated long-term in the brain after exposure to ionizing radiation

Ionizing radiation stimulates miR-21 expression in different types of mammalian cells in culture. However, it remains unclear whether radiation could stimulate miR-21 expression in brain cells and tissue and, if so, how long the upregulation of miR-21 would be maintained after exposure to different types of radiation. To answer these questions, we examined the miR-21 levels in irradiated mouse hippocampal cells and brain tissue from mice at different times up to 1 year after whole-body exposure to 0.5 Gy of X rays [low linear energy transfer (LET)] or (56)Fe ions (high LET). The results showed that radiation stimulated miR-21 expression in mouse hippocampal cells and upregulation of EGFR, which is similar to that in human hepatocytes, as we reported previously. Interestingly, the miR-21 levels gradually increased within 1 year after irradiation, although there was no significant difference in the miR-21 low- and high-LET irradiated mice. The high expression of miR-21 in the brain was also associated with high expression of EGFR in irradiated mice; thus our data strongly support that EGFR and miR-21 are in a positive regulatory loop, because it is known that radiation stimulates miR-21 through the EGFR/Stat3 pathway and miR-21 activates the EGFR pathway. Since the brain is relatively resistant to radiation-induced histomorphological changes, our findings may provide a new way to explore radiation-induced pathological changes in the brain by investigating miR-21 and its multiple targets.     

Effects of gamma radiation on beta-lactoglobulin: oligomerization and aggregation

The conformational changes and aggregation process of beta-lactoglobulin (beta-LG) subjected to gamma irradiation are presented. Beta-LG in solutions of different protein concentrations (3 and 10 mg/ml) and in solid state with different water activities (a(w)) (0.22; 0.53; 0.74) was irradiated using a Cobalt-60 radiation source at dose level of 1-50 kGy. Small-angle X-ray scattering (SAXS) was used to study the conformational changes of beta-LG due to the irradiation treatment. The irradiated protein was also examined by high performance size exclusion chromatography (HPSEC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing and reducing conditions and fluorescence. SAXS analysis showed that the structural conformation of irradiated beta-LG in solid state at different a(w) and dose level was essentially the same as the nonirradiated beta-LG. The scattering data also showed that the irradiation of beta-LG in solution promoted the formation of oligomers. Interestingly, from the data analysis and model building, it could be shown that the formed oligomers are linear molecules, built by linear combinations of beta-LG dimers (tetramers, hexamers, etc). The formation of oligomers was also evidenced by SDS-PAGE analysis and HPSEC chromatograms, in which products with higher molecular mass than that of the dimeric beta-LG were detected. Formation of intermolecular cross-linking between tyrosyl radicals are proposed to be at least partially responsible for this occurrence. From the results it could be shown that the samples irradiated in solution presented some conformational changes under gamma irradiation, resulting in well ordered oligomers and aggregates formed by cross-linking of beta-LG dimers subunits, while the samples irradiated in the solid state were not modified.     

云南报春花SOD、POD酶量月际性变化与UV-B辐射关系的研究

利用低纬高原地区获得部分不同地区紫外辐射观测资料,研究不同地区紫外辐射月际性差异引起云南报春花SOD、POD酶量的差异变化,探讨在自然环境条件下,UV-B辐射对植物体内SOD、POD的影响。结果表明: (1)在低纬高原地区UV-B辐射强度变化具有特殊性和复杂性;(2)当报春花处于幼苗生长期(2月)时,UV-B辐射强度小,SOD、POD活性表现较弱;进入生长旺盛期和开花期(3月、4月),UV-B辐射增强,此时SOD、POD活性也随之增强;进入衰老期(5月),而UV-B继续增强,植物SOD、POD酶活性下降。     

Biotic diachroneity during the Ordovician Radiation: evidence from South China

The Ordovician radiation was one of the most marked and sustained increases in Phanerozoic biodiversification; nevertheless it occurred against a background of minimal global climatic and environmental perturbations. Detailed investigations of the Ordovician successions on the Yangtze Platform of the South China palaeoplate indicate that: (1) the brachiopod α- and β-diversity changes are diachronous; (2) macroevolutionary patterns were different across the South China palaeoplate, with the Early Ordovician brachiopod radiation first occurring in normal marine, shallow-water environments and then moving gradually to both nearer-shore and offshore locations; (3) the main contributors to the initial Ordovician brachiopod radiation were the Orthida and Pentamerida; the typical Ordovician brachiopod fauna, dominated by the Orthida and Strophomenida, did not appear until the late Mid Ordovician (Undulograptus austrodentatus Biozone) when the Strophomenida apparently replaced the dominant position of the Pentamerida within the fauna; (4) different ecotypes (e.g., sessile benthos, mobile benthos together with pelagic and planktonic organisms) demonstrate substantially different macroevolutionary patterns. The Ordovician brachiopod radiation of South China was apparently earlier than that suggested by global trends together with the data available from other palaeoplates or terranes, which may be related to its unique palaeogeographic position (peri-Gondwanan terrane gradually moving to equatorial latitudes).     

Studies on the mechanism of radiation-induced structural disorganization of human erythrocyte membranes

The structural changes of human erythrocyte membranes after X-irradiation were investigated with the aid of fluorescent probes. It was found that the fluorescence characteristics (intensity, polarization and the dissociation constant) of 1-anilino-8-naphthalene sulphonate (ANS) bound to X-irradiated (up to 40 Gy) membranes were quite different from those in unirradiated ones. Sulphydryl (SH)-oxidizing reagents showed the same effects as X-rays on the ANS fluorescence. In addition, pretreatment of the membranes with SH reagents completely blocked the radiation-induced fluorescence changes. These results demonstrated that the initial cause of the radiation effect on membranes is the oxidation of membrane SH groups. There were two different steps in the development of the radiation effect on membrane structure; one is the radiation chemical reaction of SH groups, which is independent of the post-irradiation incubation temperature, and the other is markedly influenced by the temperature, particularly between 12 and 26 degrees C. Therefore it was concluded that structural disorganization of the membranes, including rearrangement of membrane components, might take place following exposure to radiation. This was supported by the fact that treatment with detergents mimicked the effect of X-irradiation. The reaction of OH and/or O2- from the aqueous environment was shown to be responsible for the membrane effect of radiation.     

Time-dependent changes of the physiological status of Bromus inermis Leyss. seeds from chronic low-level radiation exposure areas

The seed progeny of smooth brome (Bromus inermis Leyss.) were evaluated over a year for their viability, mutation rate, resistance to radiation and antioxidant status in response to chronic radiation exposure. Bromus inermis is found in the Eastern Ural Radioactive Trace (EURT) area and the background territories (surrounding territories that are used as controls as they only have natural background radiation). The absorbed doses by smooth brome from the EURT area were 1.5–18.5 times higher compared to background locations for parent plants and 1.1–11.6 times higher for the seed embryos. There are predictable and asynchronous changes in the survival of shoots and root growth rate between background populations and chronically irradiated samples. The provocative dose of 250 Gy is more damaging in the winter months, than in the summer and autumn. The frequency of anomalies in shoots varied in different months, with the biggest rate of mutation recorded in physiologically harsher period (autumn–winter). There is no correlation between resulting survival rate of shoots and their resistance to radiation. The intense activity of the antioxidant systems (estimated by the content of low molecular weight antioxidants) allowed faster growth of the shoots and reduced the number of abnormalities seen in development.     

Spatially fractionated radiation induces cytotoxicity and changes in gene expression in bystander and radiation adjacent murine carcinoma cells

Radiation-induced bystander effects have been extensively studied at low doses, since evidence of bystander induced cell killing and other effects on unirradiated cells were found to be predominant at doses up to 0.5 Gy. Therefore, few studies have examined bystander effects induced by exposure to higher doses of radiation, such as spatially fractionated radiation (GRID) treatment. In the present study, we evaluate the ability of GRID treatment to induce changes in GRID adjacent (bystander) regions, in two different murine carcinoma cell lines following exposure to a single irradiation dose of 10 Gy. Murine SCK mammary carcinoma cells and SCCVII squamous carcinoma cells were irradiated using a brass collimator to create a GRID pattern of nine circular fields 12 mm in diameter with a center-to-center distance of 18 mm. Similar to the typical clinical implementation of GRID, this is approximately a 50:50 ratio of direct and bystander exposure. We also performed experiments by irradiating separate cultures and transferring the medium to unirradiated bystander cultures. Clonogenic survival was evaluated in both cell lines to determine the occurrence of radiation-induced bystander effects. For the purpose of our study, we have defined bystander cells as GRID adjacent cells that received approximately 1 Gy scatter dose or unirradiated cells receiving conditioned medium from irradiated cells. We observed significant bystander killing of cells adjacent to the GRID irradiated regions compared to sham treated controls. We also observed bystander killing of SCK and SCCVII cells cultured in conditioned medium obtained from cells irradiated with 10 Gy. Therefore, our results confirm the occurrence of bystander effects following exposure to a high-dose of radiation and suggest that cell-to-cell contact is not required for these effects. In addition, the gene expression profile for DNA damage and cellular stress response signaling in SCCVII cells after GRID exposure was studied. The occurrence of GRID-induced bystander gene expression changes in significant numbers of DNA damage and cellular stress response signaling genes, providing molecular evidence for possible mechanisms of bystander cell killing.