Lessons from past radiation accidents: Critical review of methods addressed to individual dose assessment of potentially exposed people and integration with medical assessment

The experiences of the Chernobyl and Fukushima nuclear accidents showed that dosimetry was the essential tool in the emergency situation for decision making processes, such as evacuation and application of protective measures. However, at the consequent post-accidental phases, it was crucial also for medical health surveillance and in further adaptation to changed conditions with regards to radiation protection of the affected populations. This review provides an analysis of the experiences related to the role of dosimetry (dose measurements, assessment and reconstruction) regarding health preventive measures in the post-accidental periods on the examples of the major past nuclear accidents such as Chernobyl and Fukushima. Recommendations derived from the review are called to improve individual dose assessment in case of a radiological accident/incident and should be considered in advance as guidelines to follow for having better information. They are given as conclusions.

Eurados review of retrospective dosimetry techniques for internal exposures to ionising radiation and their applications

This work presents an overview of the applications of retrospective dosimetry techniques in case of incorporation of radionuclides. The fact that internal exposures are characterized by a spatially inhomogeneous irradiation of the body, which is potentially prolonged over large periods and variable over time, is particularly problematic for biological and electron paramagnetic resonance (EPR) dosimetry methods when compared with external exposures. The paper gives initially specific information about internal dosimetry methods, the most common cytogenetic techniques used in biological dosimetry and EPR dosimetry applied to tooth enamel. Based on real-case scenarios, dose estimates obtained from bioassay data as well as with biological and/or EPR dosimetry are compared and critically discussed. In most of the scenarios presented, concomitant external exposures were responsible for the greater portion of the received dose. As no assay is available which can discriminate between radiation of different types and different LETs on the basis of the type of damage induced, it is not possible to infer from these studies specific conclusions valid for incorporated radionuclides alone. The biological dosimetry assays and EPR techniques proved to be most applicable in cases when the radionuclides are almost homogeneously distributed in the body. No compelling evidence was obtained in other cases of extremely inhomogeneous distribution. Retrospective dosimetry needs to be optimized and further developed in order to be able to deal with real exposure cases, where a mixture of both external and internal exposures will be encountered most of the times.

Realism and usefulness of multispecies experiment designs with regard to application in radioecology: A review

Multispecies experiments like microcosms and mesocosms are widely used in many fields of research but not in radioecology. In radioecology, size limitations are important as large experimental volumes involve problems with waste (radionuclides), or shielding, absorption and available space in gamma fields (often within a climate chamber). We have therefore performed a literature review (ISI Web of Science, n = 406) of the design and properties of multispecies effect studies <100 L in size and with three or more mentioned taxa in other research fields to assess their suitability to radioecology. Studies with more mentioned taxa assess structural ecosystem parameters more often than studies with fewer mentioned taxa, while the opposite trend is seen for indirect effects/interactions. Studies of indirect effects benefit from more replicates and longer experiments. Almost all studies assess some ecosystem level parameter but only a quarter take a holistic approach assessing both structural and functional as well as indirect effects. We find that most cosms are custom-made systems, rather than standardised designs. Unmanipulated cosms consist of excised portions of the natural environment with a higher number of mentioned taxa, high ecological complexity and high realism, but have a relatively low replicability. In contrast, standardised cosms with fewer mentioned taxa have less ecological complexity but much higher replicability. This literature review shows that smaller cosm sizes have similar ecological complexity (e.g. number of taxa and trophic levels) and experimental duration as larger sized cosms, allowing for ecologically-relevant investigations, despite their small size. We encourage multispecies radioecology studies, preferably with environmental relevant doses and sufficient detail on dosimetry.

Uncertainty of fast biological radiation dose assessment for emergency response scenarios

PURPOSE

Reliable dose estimation is an important factor in appropriate dosimetric triage categorization of exposed individuals to support radiation emergency response.

MATERIALS AND METHODS

Following work done under the EU FP7 MULTIBIODOSE and RENEB projects, formal methods for defining uncertainties on biological dose estimates are compared using simulated and real data from recent exercises.

RESULTS

The results demonstrate that a Bayesian method of uncertainty assessment is the most appropriate, even in the absence of detailed prior information. The relative accuracy and relevance of techniques for calculating uncertainty and combining assay results to produce single dose and uncertainty estimates is further discussed.

CONCLUSIONS

Finally, it is demonstrated that whatever uncertainty estimation method is employed, ignoring the uncertainty on fast dose assessments can have an important impact on rapid biodosimetric categorization.

RENEB accident simulation exercise

PURPOSE

The RENEB accident exercise was carried out in order to train the RENEB participants in coordinating and managing potentially large data sets that would be generated in case of a major radiological event.

MATERIALS AND METHODS

Each participant was offered the possibility to activate the network by sending an alerting email about a simulated radiation emergency. The same participant had to collect, compile and report capacity, triage categorization and exposure scenario results obtained from all other participants. The exercise was performed over 27 weeks and involved the network consisting of 28 institutes: 21 RENEB members, four candidates and three non-RENEB partners.

RESULTS

The duration of a single exercise never exceeded 10 days, while the response from the assisting laboratories never came later than within half a day. During each week of the exercise, around 4500 samples were reported by all service laboratories (SL) to be examined and 54 scenarios were coherently estimated by all laboratories (the standard deviation from the mean of all SL answers for a given scenario category and a set of data was not larger than 3 patient codes).

CONCLUSIONS

Each participant received training in both the role of a reference laboratory (activating the network) and of a service laboratory (responding to an activation request). The procedures in the case of radiological event were successfully established and tested.

Amyloid-PET predicts inhibition of de novo plaque formation upon chronic γ-secretase modulator treatment

In a positron-emission tomography (PET) study with the β-amyloid (Aβ) tracer [(18)F]-florbetaben, we previously showed that Aβ deposition in transgenic mice expressing Swedish mutant APP (APP-Swe) mice can be tracked in vivo. γ-Secretase modulators (GSMs) are promising therapeutic agents by reducing generation of the aggregation prone Aβ42 species without blocking general γ-secretase activity. We now aimed to investigate the effects of a novel GSM [8-(4-Fluoro-phenyl)-[1,2,4]triazolo[1,5-a]pyridin-2-yl]-[1-(3-methyl-[1,2,4]thiadiazol-5-yl)-piperidin-4-yl]-amine (RO5506284) displaying high potency in vitro and in vivo on amyloid plaque burden and used longitudinal Aβ-microPET to trace individual animals. Female transgenic (TG) APP-Swe mice aged 12 months (m) were assigned to vehicle (TG-VEH, n=12) and treatment groups (TG-GSM, n=12), which received daily RO5506284 (30 mg kg(-1)) treatment for 6 months. A total of 131 Aβ-PET recordings were acquired at baseline (12 months), follow-up 1 (16 months) and follow-up 2 (18 months, termination scan), whereupon histological and biochemical analyses of Aβ were performed. We analyzed the PET data as VOI-based cortical standard-uptake-value ratios (SUVR), using cerebellum as reference region. Individual plaque load assessed by PET remained nearly constant in the TG-GSM group during 6 months of RO5506284 treatment, whereas it increased progressively in the TG-VEH group. Baseline SUVR in TG-GSM mice correlated with Δ%-SUVR, indicating individual response prediction. Insoluble Aβ42 was reduced by 56% in the TG-GSM versus the TG-VEH group relative to the individual baseline plaque load estimates. Furthermore, plaque size histograms showed differing distribution between groups of TG mice, with fewer small plaques in TG-GSM animals. Taken together, in the first Aβ-PET study monitoring prolonged treatment with a potent GSM in an AD mouse model, we found clear attenuation of de novo amyloidogenesis. Moreover, longitudinal PET allows non-invasive assessment of individual plaque-load kinetics, thereby accommodating inter-animal variations.

Simultaneous intracellular redox potential and pH measurements in live cells using SERS nanosensors

Intracellular redox potential is a highly regulated cellular characteristic and is critically involved in maintaining cellular health and function. The dysregulation of redox potential can result in the initiation and progression of numerous diseases. Redox potential is determined by the balance of oxidants and reductants in the cell and also by pH. For this reason a technique for quantitative measurement of intracellular redox potential and pH is highly desirable. In this paper we demonstrate how surface enhanced Raman scattering (SERS) nanosensors can be used for multiplexed measurement of both pH and redox potential in live single cells.

Realising the European network of biodosimetry: RENEB-status quo

Creating a sustainable network in biological and retrospective dosimetry that involves a large number of experienced laboratories throughout the European Union (EU) will significantly improve the accident and emergency response capabilities in case of a large-scale radiological emergency. A well-organised cooperative action involving EU laboratories will offer the best chance for fast and trustworthy dose assessments that are urgently needed in an emergency situation. To this end, the EC supports the establishment of a European network in biological dosimetry (RENEB). The RENEB project started in January 2012 involving cooperation of 23 organisations from 16 European countries. The purpose of RENEB is to increase the biodosimetry capacities in case of large-scale radiological emergency scenarios. The progress of the project since its inception is presented, comprising the consolidation process of the network with its operational platform, intercomparison exercises, training activities, proceedings in quality assurance and horizon scanning for new methods and partners. Additionally, the benefit of the network for the radiation research community as a whole is addressed.

Operational guidance for radiation emergency response organisations in Europe for using biodosimetric tools developed in EU MULTIBIODOSE project

In the event of a large-scale radiological emergency, the triage of individuals according to their degree of exposure forms an important initial step of the accident management. Although clinical signs and symptoms of a serious exposure may be used for radiological triage, they are not necessarily radiation specific and can lead to a false diagnosis. Biodosimetry is a method based on the analysis of radiation-induced changes in cells of the human body or in portable electronic devices and enables the unequivocal identification of exposed people who should receive medical treatment. The MULTIBIODOSE (MBD) consortium developed and validated several biodosimetric assays and adapted and tested them as tools for biological dose assessment in a mass-casualty event. Different biodosimetric assays were validated against the 'gold standard' of biological dosimetry-the dicentric assay. The assays were harmonised in such a way that, in an emergency situation, they can be run in parallel in a network of European laboratories. The aim of this guidance is to give a concise overview of the developed biodosimetric tools as well as how and when they can be used in an emergency situation.

Realising the European Network of Biodosimetry (RENEB)

In Europe, a network for biological dosimetry has been created to strengthen the emergency preparedness and response capabilities in case of a large-scale nuclear accident or radiological emergency. Through the RENEB (Realising the European Network of Biodosimetry) project, 23 experienced laboratories from 16 European countries will establish a sustainable network for rapid, comprehensive and standardised biodosimetry provision that would be urgently required in an emergency situation on European ground. The foundation of the network is formed by five main pillars: (1) the ad hoc operational basis, (2) a basis of future developments, (3) an effective quality-management system, (4) arrangements to guarantee long-term sustainability and (5) awareness of the existence of RENEB. RENEB will thus provide a mechanism for quick, efficient and reliable support within the European radiation emergency management. The scientific basis of RENEB will concurrently contribute to increased safety in the field of radiation protection.

Effects of different gamma exposure regimes on reproduction in the earthworm Eisenia fetida (Oligochaeta)

Ecological risk assessment of ionising radiation requires knowledge about the responses of individuals and populations to chronic exposures, including situations when exposure levels change over time. The present study investigated processes such as recovery and the adaptive response with respect to reproduction endpoints in the earthworm Eisenia fetida exposed to (60)Co γ-radiation. Furthermore, a crossed experiment was performed to investigate the influence of F0 parental and F1 embryonic irradiation history on the response of irradiated or non-irradiated F1 offspring. Recovery: The sterility induced by sub-chronic exposure at 17 m Gy/h (accumulated dose: 25 Gy) was temporary, and 8 weeks after irradiation the worms had regained their reproductive capacity (number of viable offspring produced per adult per week). Adaptive response: Adult worms were continuously exposed at a low priming dose rate of 0.14 mGy/h for 12 weeks (accumulated dose: 0.24 Gy), followed by 14 weeks exposure at a challenge dose rate of 11 mGy/h. The results suggest a lack of adaptive response, since there were no significant differences in the effects on reproduction capacity between the primed and the unprimed groups after challenge doses ranging from 7.6 to 27 Gy. Crossed experiment: The effects of exposure at 11 mGy/h for 21 weeks on growth, sexual maturation and reproduction of offspring, derived either from parent worms and cocoons both exposed at 11 mGy/h, or from non-irradiated parents and cocoons (total accumulated dose 44 and 38 Gy, respectively) were compared. There were no significant differences between the two exposed offspring groups for any of the endpoints. The reproduction capacity was very low for both groups compared to the controls, but the reproduction seemed to be maintained at the reduced level, which could indicate acclimatisation or stabilisation. Finally, parental and embryonic exposures at 11 mGy/h did not affect reproduction in the F1 offspring as adults.

Review of retrospective dosimetry techniques for external ionising radiation exposures

The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements.

Recommendations from the International Union of Radioecology to improve guidance on radiation protection

This brief commentary summarizes the views of a working group assembled by the International Union of Radioecology to advance the approaches used to evaluate effects of radioactive materials in the environment. The key message in both the research needs and the recommendations for management of radioactive materials centers around the need to adopt an ecocentric approach that recognizes the interconnectedness of biota, including humans, and ecological processes.

A new handbook on triage, monitoring and treatment of people following malevolent use of radiation

Through the Euratom 6 Framework Programme, the European Commission is co-sponsoring the specific targeted research project "Triage, Monitoring and Treatment-Handbook for management of the public in the event of malevolent use of radiation" (TMT Handbook). The main aim of the project is to produce a handbook for the effective and timely triage, monitoring, and treatment of people exposed to radiation following a malevolent act. The World Health Organization contributed to this project with development of guidelines on medical and public health response. A training course based on the TMT Handbook was developed. It will help to enhance national capacity for planning and response to acts involving the malevolent use of radiation. The course will also provide a platform to identify common challenges and discuss opportunities for harmonizing response strategies throughout the European Union. Focusing on its medical and public health response aspects, this paper introduces the TMT Handbook and its potential applicability not only as practical guidance for end-users but also as a useful tool for education and training.

Modeling and multi-response optimization of pervaporation of organic aqueous solutions using desirability function approach

The factorial design of experiments and desirability function approach has been applied for multi-response optimization in pervaporation separation process. Two organic aqueous solutions were considered as model mixtures, water/acetonitrile and water/ethanol mixtures. Two responses have been employed in multi-response optimization of pervaporation, total permeate flux and organic selectivity. The effects of three experimental factors (feed temperature, initial concentration of organic compound in feed solution, and downstream pressure) on the pervaporation responses have been investigated. The experiments were performed according to a 2(3) full factorial experimental design. The factorial models have been obtained from experimental design and validated statistically by analysis of variance (ANOVA). The spatial representations of the response functions were drawn together with the corresponding contour line plots. Factorial models have been used to develop the overall desirability function. In addition, the overlap contour plots were presented to identify the desirability zone and to determine the optimum point. The optimal operating conditions were found to be, in the case of water/acetonitrile mixture, a feed temperature of 55 degrees C, an initial concentration of 6.58% and a downstream pressure of 13.99 kPa, while for water/ethanol mixture a feed temperature of 55 degrees C, an initial concentration of 4.53% and a downstream pressure of 9.57 kPa. Under such optimum conditions it was observed experimentally an improvement of both the total permeate flux and selectivity.

Types of radiation mass casualties and their management

Management of radiation mass casualty exposure that may occur as a result of nuclear or radiation accident will depend on the type of accident, and of the knowledge about the actual radiation exposure situation for those who might be involved. Management of the public after an accident in a nuclear or radiation installation will follow existing specific emergency plans, and will take advantage of existing radiation monitoring systems. In other radiation mass casualty exposures, whenever accidental or malevolent use of radiation, there will be a requirement to employ screening programs for indentifying and sorting out exposed people (radiological triage), who will need medical treatment and/or other assistance like decontamination and individual dose assessment. In the later stage after the accident the monitoring for dose assessment purposes for those who will need medical or public health assistance will be required. Demand for dose assessment for large groups of individuals may create the need for international assistance. Prompt and credible public information is vital in all radiation emergencies, and it would be even more important in situations when radiation mass casualties result from exposures to nuclear or radiological material out of regulatory control. In such situations unpredictability of the event creates increase in the risk perception and public communication activities of the authorities will be the key element to prevent unnecessary fear and panic, and the measure to reassure the populace.

Medical and radiological aspects of emergency preparedness and response at SevRAO facilities

Regulatory cooperation between the Norwegian Radiation Protection Authority and the Federal Medical Biological Agency (FMBA) of the Russian Federation has the overall goal of promoting improvements in radiation protection in Northwest Russia. One of the projects in this programme has the objectives to review and improve the existing medical emergency preparedness capabilities at the sites for temporary storage of spent nuclear fuel and radioactive waste. These are operated by SevRAO at Andreeva Bay and in Gremikha village on the Kola Peninsula. The work is also intended to provide a better basis for regulation of emergency response and medical emergency preparedness at similar facilities elsewhere in Russia. The purpose of this paper is to present the main results of that project, implemented by the Burnasyan Federal Medical Biophysical Centre. The first task was an analysis of the regulatory requirements and the current state of preparedness for medical emergency response at the SevRAO facilities. Although Russian regulatory documents are mostly consistent with international recommendations, some distinctions lead to numerical differences in operational intervention criteria under otherwise similar conditions. Radiological threats relating to possible accidents, and related gaps in the regulation of SevRAO facilities, were also identified. As part of the project, a special exercise on emergency medical response on-site at Andreeva Bay was prepared and carried out, and recommendations were proposed after the exercise. Following fruitful dialogue among regulators, designers and operators, special regulatory guidance has been issued by FMBA to account for the specific and unusual features of the SevRAO facilities. Detailed sections relate to the prevention of accidents, and emergency preparedness and response, supplementing the basic Russian regulatory requirements. Overall it is concluded that (a) the provision of medical and sanitary components of emergency response at SevRAO facilities is a priority task within the general system of emergency preparedness; (b) there is an effective and improving interaction between SevRAO and the local medical institutions of FMBA and other territorial medical units; (c) the infrastructure of emergency response at SevRAO facilities has been created and operates within the framework of Russian legal and normative requirements. Further proposals have been made aimed at increasing the effectiveness of the available system of emergency preparedness and response, and to promote interagency cooperation.

Issues and practices in the use of effects data from FREDERICA in the ERICA Integrated Approach

The ERICA Integrated Approach requires that a risk assessment screening dose rate is defined for the risk characterisation within Tiers 1 and 2. At Tier 3, no numerical screening dose rate is used, and the risk characterisation is driven by methods that can evaluate the possible effects of ionising radiation on reproduction, mortality and morbidity. Species sensitivity distribution has been used to derive the ERICA risk assessment predicted no-effect dose rate (PNEDR). The method used was based on the mathematical processing of data from FRED (FASSET radiation effects database merged with the EPIC database to form FREDERICA) and resulted in a PNEDR of 10 microGy/h. This rate was assumed to ascribe sufficient protection of all ecosystems from detrimental effects on structure and function under chronic exposure. The value was weighed against a number of points of comparison: (i) PNEDR values obtained by application of the safety factor method, (ii) background levels, (iii) dose rates triggering effects on radioactively contaminated sites and (iv) former guidelines from literature reviews. In Tier 3, the effects analysis must be driven by the problem formulation and is thus highly case specific. Instead of specific recommendations on numeric values, guidance on the sorts of methods that may be applied for refined effect analysis is provided and illustrated.

[Iodine prophylaxis following nuclear accidents]

Radioactive iodine isotopes may be released to air to a varying degree during accidents with nuclear reactors. Iodine tablets, taken before or shortly after such release, protect against intake of radioactive iodine isotopes, but not against other radionuclides. Iodine prophylaxis can be a relevant countermeasure in Norway and will be implemented according to recommendations from the Crisis Committee for Nuclear and Radiological Emergencies. The Chernobyl accident confirmed that the risk for radiogenic thyroid cancer is much higher for foetuses and children and adolescents under 18 years. An epidemiological study showed that intake of iodine tablets could reduce the risk for thyroid cancer by a factor of three. For children, the WHO has therefore recommended a 10 mGy avertable dose to the thyroid. The Norwegian Radiation Protection Authority acknowledge the WHO guidelines and advise that the first priority of all emergency preparedness planning for potential releases that can cause dispersion of radioactive iodine, should be given to the protection of pregnant and breast-feeding women, newborns and children under 18 years. Iodine tablets should be taken immediately (preferably not later than a few hours) in situations where inhalation of radioactive iodine may occur. It should be underlined that iodine prophylaxis is one of several emergency countermeasures; other measures are sheltering and evacuation. The latter two countermeasures will protect not only from intake of radioactive iodine, but also against other radionuclides that may be released. Based on the present risk assessment in Norway, iodine tablets have been distributed to the counties north of Salten. In addition, there is an emergency stockpile of iodine tablets in Oslo.

Intra- and inter-laboratory variation in the scoring of micronuclei and nucleoplasmic bridges in binucleated human lymphocytes. Results of an international slide-scoring exercise by the HUMN project

One of the objectives of the HUman MicroNucleus (HUMN) project is to identify the methodological variables that have an important impact on micronucleus (MN) or micronucleated (MNed) cell frequencies measured in human lymphocytes using the cytokinesis-block micronucleus assay. In a previous study we had shown that the scoring criteria used were likely to be an important variable. To determine the extent of residual variation when laboratories scored cells from the same cultures using the same set of standard scoring criteria, an inter-laboratory slide-scoring exercise was performed among 34 laboratories from 21 countries with a total of 51 slide scorers involved. The results of this study show that even under these optimized conditions there is a great variation in the MN frequency or MNed cell frequency obtained by individual laboratories and scorers. All laboratories ranked correctly the MNed cell frequency in cells from cultures that were unirradiated, or exposed to 1 or 2Gy of gamma rays. The study also estimated that the intra-scorer median coefficient of variation for duplicate MNed cell frequency scores is 29% for unexposed cultures and 14 and 11% for cells exposed to 1 and 2Gy, respectively. These values can be used as a standard for quality or acceptability of data in future studies. Using a Poisson regression model it was estimated that radiation dose explained 67% of the variance, while staining method, cell sample, laboratory, and covariance explained 0.6, 0.3, 6.5, and 25.6% of the variance, respectively, leaving only 3.1% of the variance unexplained. As part of this exercise, nucleoplasmic bridges were also estimated by the laboratories; however, inexperience in the use of this biomarker of chromosome rearrangement was reflected in the much greater heterogeneity in the data and the unexplained variation estimated by the Poisson model. The results of these studies indicate clearly that even after standardizing culture and scoring conditions it will be necessary to calibrate scorers and laboratories if MN, MNed cell and nucleoplasmic bridge frequencies are to be reliably compared among laboratories and among populations.

Radiation sensitivity and the status of some radiation sensitivity markers in relatively sensitive lymphoid cells

The most commonly used indicators of ionizing radiation exposure are cytogenetic measures and survival parameters. All these methods have their advantages, disadvantages and uncertainties, such that better biological estimators of the absorbed dose, especially in the low dose range, are being sought. In this study we analyzed apoptosis and several proteins involved in the regulation of apoptosis as possible indicators of irradiation after relatively small doses (0.1-2 Gy) of X-rays. The studies were carried out in seven lymphoid cell lines: two mouse lymphoma L5178Y, the human pre-B cell leukemia Reh, and four human Epstein-Barr virus-transformed lymphoid cell lines (two apparently normal and two Ataxia-telangiectasia (AT)). We detected apoptosis with the in situ terminal deoxynucleotidyl transferase assay and flow cytometry, and measured the expression of several apoptotic-regulatory proteins (Bcl-2, Bax, Bclx, NF kappa B) with Western blotting. The cytokinesis-block micronucleus assay, comet assay as a measure of DNA damage, and trypan blue survival test were also done for comparison Although for the most of examined parameters of radiation sensitivity: i.e. micronucleus assay, trypan blue test and percentage of apoptosis--there were observed clear dose-effect relationships for all cell lines examined, we did not find agreement between values for these measured parameters. There are marked differences in both timing of apoptosis and percentage of apoptotic cells. Variation in the apoptotic fraction in the controls for different sets of experiments is not very pronounced. There is however considerable variation for the same parameters in irradiated cells, possibly due to their cell cycle status during irradiation, as the cultures were not synchronized. Overall, neither the numbers of apoptotic cells nor the expression of apoptosis-related proteins, nor DNA repair can serve as dose estimators or sensors for these lines, but still these parameters can give valuable supplementary information about radiation sensitivity.

Evaluation of ionizing radiation sensitivity markers in a panel of lymphoid cell lines

PURPOSE

To examine the possible associations between radiation sensitivity to doses 2 Gy, and such features of lymphoid cell responses as apoptosis, expression of apoptosis regulatory proteins (Bcl-2 family) and cell cycle progression in relation to biological dosimetry.

MATERIALS AND METHODS

The cell lines examined were: Epstein Barr virus transformed lymphoid ataxia-telangiectasia (AT) cell lines, GM00717C, homozygous, and GM00736A, heterozygous, for ATM; human pro-B lymphoblastic leukaemia, Reh; murine L5178Y lymphoma sublines, LY-R and LY-S. Assays performed following X-irradiation with doses from 0.1 to 2 Gy were: terminal deoxyribonucleotidyl transferase (TdT) assay to measure apoptotic fraction, DNA content analysis by flow cytometry to assess cell cycle distribution, trypan blue exclusion test to determine cell viability, cytochalasin block micronucleus assay to assess cytogenetic damage, and Western blotting to detect proteins from the Bcl-2 family.

RESULTS

The cell lines in the study were of different but rather high radiation sensitivity, which was unrelated to their propensity to undergo apoptosis or micronucleus frequency. The expression of apoptotic regulatory proteins from the Bcl-2 family (constitutive and expressed 4 or 24 h after irradiation) was not related to radiation sensitivity.

CONCLUSION

None of the simple predictive tests used in the study, alone or evaluated together was suitable for detection of radiation hypersensitivity although cells known to be hypersensitive (LY-S and GM00717C) were included in the analysis.

[Evaluation of the postnatal treatment efficacy in congenital toxoplasmosis identified by the newborn screening programme]

The effectiveness of neonatal screening for anti-Toxoplasma IgM or IgA and IgM specific antibodies followed by an intensive anti-parasitic therapy for a prevention of clinical and immunological reactivations of congenital infection was studied. Thirty-five congenitally infected infants were included into clinical and serological follow-up. The children were mostly asymptomatic at birth or they expressed some non-specific reversible clinical abnormalities in neonatal period. Clinically overt toxoplasmosis occurred in 10 patients, including one infant with a severe form; 2 children had co-existing CMV infections. During the follow-up period, no clinical relapses were reported. Asymptomatic immunological rebounds of IgG or of IgG and IgA specific antibodies were observed in 16 patients. Anti-parasitic treatment initiated soon after birth seems to be promising in a prevention of early clinical sequelae of congenital T. gondii infection.

Bilirubin- and light induced cell death in a murine lymphoma cell line

Cells from the mouse lymphoma cell line L5178Y-R were exposed to blue light from phototherapy lamps in the presence of solutions of 160 microM bilirubin supplemented with serum albumin. HPLC analysis showed that the bilirubin solution was photooxidised as a function of increasing light dose. The cells were stained with trypan blue to score necrosis, and apoptosis was assayed by the terminal deoxynucleotide transferase assay (TdT) or by studying the nuclear structure in cells stained with propidium iodide. A rapidly developing apoptosis was observed after light doses killing 60-80% of the cells as judged from the trypan blue exclusion test. The fraction of apoptotic cells was smaller than the fraction of necrotic cells. Exposure of the cells to fractions of light at a high dose rate was compared to the effect of the same total dose at a lower dose rate given as a single fraction. No large differences were found, however, there was a tendency of a higher degree of necrosis as well as apoptosis in the cells receiving the light in fractions at a high dose rate.

Differential induction of apoptosis in x-irradiated L5178Y sublines bearing p53 mutation

We examined apoptosis and expression of p53, E2F-1, bax, bclx(L) and bc12 proteins in two L5178Y (LY) murine lymphoma sublines, LY-R and LY-S, which differ in radiosensitivity and double-strand break (DSB) repair. Both sublines are heterozygous for a p53 mutation in codon 170 that precludes the transactivation function. Accordingly, there is no G1/S arrest after irradiation. We found that there is no change in expression of E2F-1, bax, bclx(L) or bc12 proteins in both LY sublines after x-irradiation. LY-R cells do not constitutively express bc12, whereas both sublines show high bax content. Radiation induces delayed apoptosis to a greater extent in LY-S than in LY-R cells. The apoptosis can be seen 24 h after irradiation (2 Gy) of LY-S cells, with a maximum at 48 h. LY-R cells need 5 Gy and 72 h post-irradiation incubation to show marked apoptosis (identified by the TUNEL method). The reported observations support the assumption that differential radiosensitivity of LY sublines is associated with the induction of apoptosis that is not related to transactivation by p53 and is primarily related to differential DNA repair ability.

The effect of paraquat on the radiosensitivity of melanoma cells: the role of superoxide dismutase & catalase

The activities of reactive oxygen species scavenging enzymes, superoxide dismutases (SODs) and catalase (in cells of two melanomas (mouse B16 and human SK23) and in Chinese hamster ovary (CHO) cells were examined. Melanoma cells are relatively depleted in activities of superoxide dismutases and catalase as compared to CHO cells. Short equitoxic (500 microM for CHO and B16 cells and 5 microM for SK23 cells) paraquat treatment (15 min before the X-irradiation, 45 min in postirradiation period--the total time of treatment was 1 h) caused an increase in radiation resistance, measured as colony forming ability, in two of the three lines examined. It is proposed that PQ may exert its radioprotective effect by induction of antioxidant enzymes.

[Late results of stomatologic and ophthalmologic treatment of injuries involving the central part of the face]

The authors present an analysis of the results of treatment of patients with injury of the central fragment of the face, who have been hospitalized in the 2nd Department of the Maxillofacial surgery in Silesian Academy of Medicine. In the period 1980-1987 there were 447 patients with an injury of the central fragment of the face. Among this group 60 (13.4 p.c.) patients showed disturbances of the visual system. The most frequent causes of the injury were: assault (61.5 p.c.), traffic accidents (20.1 p.c.), occupational injuries (8.8 p.c.). Deformation of the face was the most frequent pathology observed in the course of a control stomatological check-up (32.0 p.c.). The most important ocular pathology were the posttraumatic atrophy of the eye (3.3 p.c.) and optic atrophy. Palpebral scars (33 p.c.) and diplopia (7.6 p.c.) were the most frequent ocular signs.

Paraquat increases superoxide dismutase activity and radiation resistance in two mouse lymphoma L5178Y cell strains of different radiosensitivities

It is shown that paraquat treatment (1 h, 1 x 10(-5) mol/l) increases the activity of superoxide dismutase (SOD) in L5178Y (LY) R and S cells by about three times. When combined with X-irradiation, 0.5 h of treatment preceding irradiation increased the SOD activity two-fold and the alpha/beta ratio three-fold, as estimated from the X-ray survival curves. LY-S cells were more sensitive than LY-R cells to treatment with paraquat alone. These results indicate that SOD may be a radioprotective enzyme in LY strains and that LY-S cells are particularly sensitive to superoxide radicals as a result of a relatively low SOD activity. This explains their sensitivity to paraquat, which generates O2-, and to X-rays. The low SOD level may also explain the higher initial DNA damage in X-irradiated LY-S than LY-R cells.

Structure-activity relationship of polyamine derivatives of 1,3-dichloroacetone-thiosemicarbazone: induction of metastases and increase in sialylation of murine lymphoma L5178Y-R cells

A number of polyamine (PA) derivatives of thiosemicarbazone of 1,3-dichloroacetone (TDA) have been prepared and their effect on growth in vivo of tumorigenic but not metastatic cell strain (LY-R) of mouse lymphoma L5178Y has been investigated. Polyamine derivatives of TDA (PDT) were injected i.p. every third day (4 times, 10 or 25 mg/kg per injection) into DBA/2 mice inoculated i.p. or s.c. with LY-R cells. It has been found that disubstituted putrescine (Put), spermidine (Spd) and spermine (Spm) derivatives TDA exhibit a prometastatic activity as indicated by the appearance of solid tumor foci in subcutaneous tissues, liver and spleen. This activity depends mainly on the structure of the PA fragment and the presence of TDA. An increase in lipid bound sialic acid content after treating LY-R cells in vitro and in vivo with a Spm derivative has been found. These findings suggest that disubstituted PA derivatives of TDA and LY-R cells may be a useful model for investigation of the final steps in formation of metastases by lymphoma cells.

[Evaluation of the indications for conservative and surgical treatment of mandibular fractures in the light of late therapeutic results. Own material results of studies]

The studied material comprised 300 inpatients with mandibular fractures in whom the data necessary for the intended assessment were collected according to an acc epted programme. The collected material made possible to evaluate the indications to surgical and conservative treatment in the light of immediate and late results considering the duration of the treatment and its effectiveness, and the time of disability to work or school work. On the basis of the obtained therapeutic results the necessity was demonstrated of introduction of slight corrections in the presently accepted indications to the choice of treatment type. The result of the study is a suggestion for extension of the indications to surgical treatment with consideration of the modern methods of osteosynthesis in certain groups of patients with mandibular fractures. It was noted that a considerable number of patients had too long, unjustified illness leaves from work which the authors regard as a sociological phenomenon requiring further studies.

[Tuberculosis of jaw bones]

The authors report three cases of isolated tuberculous foci of jaw bones and stress the increase in the prevalence of tuberculosis in last years. The process had a protracted course and was associated with isolated or multiple pus-discharging fistulae. In all cases the final diagnosis was based on the histological examination of scrapings from the pathological lesions. In one case establishing of correct diagnosis was very difficult since the initial laboratory investigations and microscopic examination of cells from the pus and sputum failed to demonstrate specific changes. Only later histological examination during repeated exacerbations demonstrated tuberculosis. The treatment with tuberculostatic agents made possible achieving of improvement.