Exposures to ionising radiation resulting from natural sources or medical diagnostics are generally very low. In contrast, exposures to therapeutic radiation, although, they are often partial exposures, represent much higher doses. Similar levels of exposure may also occur as a consequence of a radiological accident, where it would be necessary to quickly separate individuals requiring urgent medical attention from the “worried-well”. The well-established biodosimetry techniques based on cytogenetics, particularly scoring dicentric chromosomes, are accurate and sensitive, yet, they are unsuitable for mass screening due to limited capacity and the time required for providing dose estimates. Measuring gene expression changes following radiation exposure was suggested over a decade ago to be an alternative method for dose estimation, as it is a quick, sensitive and suitable technique for high throughput application. The qPCR protocol was extensively optimised for increased reproducibility and sensitivity in order to be suitable for biodosimetry purposes. Radiation-responsive transcripts were identified and characterised in terms of temporal- and dose-responses. Finally, candidate transcripts were validated in human blood irradiated ex vivo and in vivo in blood samples obtained from cancer patients undergoing radiotherapy treatment. The data generated here serve as a proof of principle that qPCR-based gene expression assays can be used for radiation biodosimetry purposes to aid classical cytogenetics tools in an event of mass causality.

The benefits of low UV dose treatment of horticultural produce – also known as hormetic treatment - have been attested to in numerous studies conducted over the last 15 years. However, commercial growers have not adopted the concept of hormesis. With increasingly stringent controls on the use of fungicides and other chemical agents the time has come to examine how hormetic treatment might be applied in the horticulture sector. The objectives of this work were firstly, to confirm UV-induced hormetic effects applied postharvest for a number of different types of produce, namely, tomatoes, broccoli, strawberries and mangoes. Secondly, to evaluate the use of rollers to ensure full surface treatment of produce, and thirdly to evaluate the possibility of treating produce preharvest. In order to investigate surface UV dose distributions, a polystyrene sphere (Diameter 70 mm) was used to simulate fruits such as tomatoes, apples, peaches etc., that have an approximately spherical form. Biodosimetry based on spores of Bacillus subtilis was employed to experimentally determine UV doses and to compare the results obtained with theoretical predictions. Good agreement was obtained and the modelling approach was extended to other types of produce. This showed the amenability of mechanical rollers to ensure full surface treatment of produce. Postharvest treatment of produce was carried using conventional low intensity UV sources principally emitting at 254 nm and also a commercially available high energy pulsed UV source. Treatment using the conventional UV source was carried out on mechanical rollers within a UV cabinet designed for this work at a fixed distance from the source and at an intensity of 1000 μW/cm2. A 5 minute conventional UV treatment of tomatoes was approximately comparable to fruit given a 3-pulsed treatment using the pulsed source (507 J/pulse of polychromatic light). The colour and texture of both groups of fruit were significantly maintained as compared with controls. The treated tomatoes also showed a significant increase in the ascorbic acid levels during storage. Similarly, a 15 minute conventional UV treatment of broccoli heads was comparable to heads given a 10-pulsed treatment using the pulsed source. Where both treatments gave rise to a statistically significant retention of green colour of treated broccoli. In addition, mangoes given a 10 minute conventional UV treatment were comparable to fruit given a 20-pulsed treatment using the pulsed source with both treatments leading to maintenance of texture as compared to control fruit. This confirmed the UV-hormetic effects. The effects of conventional and pulsed treatments are compared and discussed. Preharvest treatment of tomatoes and strawberries was carried out in commercial glasshouses. Doses of either 3 or 8 kJ/m2 were delivered to the fruits using a treatment device designed for the work, which delivered a combined intensity of 2000 μW/cm2 from two low pressure UV sources. The treated tomatoes showed a delay in development of colour as measured on the vine and after picking. Picked tomatoes were inoculated with P. digitatum and C. gloeosporioides and the results obtained showed a significant inhibition of the development of the fungi in the treated fruit during the storage period. These results suggest that the beneficial response shown by the preharvest treatment is not a localised one but a systematically induced resistance observable throughout the treated plant. This was shown by monitoring tomato fruits on treated plants which themselves where not directly exposed to the UV light. The two doses elicited different responses in the treated strawberries, with the 8 kJ/m2 dose causing the fruit to redden significantly faster than the 3 kJ/m2 treated fruits and controls. This could have significant nutritional benefit as the red colour of strawberries has been correlated with anthocyanin levels. On the other hand, treatment at the lower UV dose led to a lag in colour development. The amenability of the equipment utilised for commercial application is discussed.

The general public is at risk of ionising-radiation exposure. The development of high-throughput methods to triage exposures is warranted. Current biodosimetry techniques are low-throughput and encumbered by time and technical expertise. Although there has been an emergence of gene-profiling tools for the purpose of photon biodosimetry, similar capacities do not exist for alpha-particle radiation. Herein is the first genomic study useful for alpha-particle radiation biodosimetric triage. This work has identified robust alpha-particle induced gene-based biomarkers in isolated, ex-vivo irradiated leukocytes from multiple donors. It was found that alpha-particle and photon radiation elicited similar transcriptional responses, which could potentially be distinguished by aggregate-signature analysis. Although no distinct genes were sole indicators of exposure type, clustering algorithms and principal component analysis were able to demarcate radiation type with some success. By comparing the biological effects elicited by photon and alpha-particle radiation, significant contributions have been made to the field of radiation biodosimetry.

In the thesis I focus on evaluation of the effect of familiar occurrence of cancer on presence and number of micro-nuclei in blood preparations with particular groups of persons. One of the biodosimetry methods, test for presence, number and kind of micro-nuclei, was used. I was not investigating the dosages as such and connection of the number of micro-nuclei with the dose, however, I followed up the effect of potentially influencing side factor on presence and number of micro-nuclei, which is the familiar occurrence of tumour. As a lot of information about ionizing radiation, its sources, radioactivity, radio-biologically important quantities, mechanisms of effects, molecular and cellular changes and biodosimetric methods as such falls under the topic, the theoretical part of diploma project is dedicated to such information. In the practical part, evaluation of the number and kind of micro-nuclei with set groups of persons is carried out. These groups of persons are particularly exposed to ? radiation. They are employees of spa Lázně Jáchymov, former miners from already closed uranium mines in Příbram and current miners from uranium mines GEAM o. z. Dolní Rožínka. These selected persons are divided according to their workplaces into two groups, i.e. a group of persons without cancer occurrence in the family and a group of persons with occurrence of cancer in their families. The numbers of bi-nuclei cells without micro-nuclei and with micro-nuclei and the kinds of micro-nuclei were determined with all these persons using fluorescence microscope. Expression and comparison of percentages of bi-nuclei cells with micro-nuclei to total number of all bi-nuclei followed and then expression and comparison of proportion of micro-nuclei without centromeres to the number of micro-nuclei of both kinds (with centromeres and without centromeres) with all persons and groups were carried out. Based on the results gained from statistical assessment, it was found that differences between percentages of the two main compared groups of persons did not show higher genomic instability (statistically significant difference) in persons with familiar occurrence of cancer than in persons without cancer in the family. But by comparing the shares of micronuclei without centromeres was proved statistically significant difference between these main groups.

The general public is at risk of ionising-radiation exposure. The development of high-throughput methods to triage exposures is warranted. Current biodosimetry techniques are low-throughput and encumbered by time and technical expertise. Although there has been an emergence of gene-profiling tools for the purpose of photon biodosimetry, similar capacities do not exist for alpha-particle radiation. Herein is the first genomic study useful for alpha-particle radiation biodosimetric triage. This work has identified robust alpha-particle induced gene-based biomarkers in isolated, ex-vivo irradiated leukocytes from multiple donors. It was found that alpha-particle and photon radiation elicited similar transcriptional responses, which could potentially be distinguished by aggregate-signature analysis. Although no distinct genes were sole indicators of exposure type, clustering algorithms and principal component analysis were able to demarcate radiation type with some success. By comparing the biological effects elicited by photon and alpha-particle radiation, significant contributions have been made to the field of radiation biodosimetry.