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Radiation Sensitivity (radiation + sensitivity)
Selected AbstractsRadiation Sensitivity and Recoverability of Listeria monocytogenes and Salmonella on 4 Lettuce TypesJOURNAL OF FOOD SCIENCE, Issue 9 2003B. A. NIEMIRAArticle first published online: 20 JUL 200 ABSTRACTListeria monocytogenes or Salmonella was inoculated onto Boston, Iceberg, Green leaf, and Red leaf lettuces. Samples were ,-irradiated, and the radiation sensitivity of the inoculated bacteria determined. Recovery of bacteria from nonirradiated leaf pieces was also measured. Although the radiation sensitivity of L. monocytogenes was not influenced by the associated lettuce type, Salmonella was significantly less sensitive on Green leaf lettuce than on Boston, Iceberg, or Red leaf lettuces. For each pathogen, the recoverability from inoculated leaf pieces was significantly different among the 4 lettuce types; the pattern of recovery of L. monocytogenes was distinct from that of Salmonella. The antimicrobial efficacy of irradiation on inoculated lettuce was influenced by relatively subtle differences between lettuce types. [source] Radiation sensitivity increases with proliferation-associated telomere dysfunction in nontransformed human epithelial cellsAGING CELL, Issue 4 2009David Soler Summary Epidemiological studies have demonstrated age differences among human adults in susceptibility to radiation, with cancer cases attributable to radiation being more frequent for older individuals at time of exposure. In addition to the notion that susceptibility increases because of progressive decline in DNA monitoring and immunosurveillance, telomere function is now emerging as a new and important factor in modulating cellular and organism sensitivity to ionizing radiation. The link between telomeres and radiosensitivity is well-documented in humans, but the causal events remain elusive. In this paper, it is shown that irradiated human epithelial cells with short dysfunctional telomeres derived from normal mammary gland display elevated DNA damage. An approach identifying the specific chromosomes with critically shortened telomeres in each donor has allowed us to conclude that short dysfunctional telomeres in human epithelial cells join radiation-induced DNA broken ends, thus interfering with their efficient repair. These findings argue against telomeres participating as sensors or transducers of DNA damage, as previously suggested. Rather, our current findings give support to the idea that dysfunctional telomeres, by acting as an additional joining option, reduce the repair fidelity of DNA broken-ends induced by radiation throughout the genome. In the mammary gland, age-dependent telomere attrition due to epithelial turnover, together with the accretion of checkpoint deficiencies, might render the accumulation of short dysfunctional telomeres. This implies that the risks associated with mammography screening could be higher than previously assumed. Our results have the possibility of imprinting a temporal dimension onto radiation sensitivity, namely, that shortened telomeres in aged cells may more easily compromise normal tissue function in the elderly. [source] Nalidixic Acid Resistance Increases Sensitivity of Escherichia coli O157:H7 to Ionizing Radiation in Solution and on Green Leaf LettuceJOURNAL OF FOOD SCIENCE, Issue 2 2005Brendan A. Niemira ABSTRACT: Nalidixic acid resistance has been used as a selective marker for studies of pathogen-inoculated fruits and vegetables. Three nalidixic acid-sensitive outbreak strains of Escherichia coli O157:H7 were used to generate mutants resistant to nalidixic acid (NalR, 50 ,g/mL) by successive culturing and selection in nalidixic acid-amended broth. The resistance to ionizing radiation of the parent and NalR strains was determined (a) in a phosphate buffer solution and (b) on green leaf lettuce. The NalR strains of each of the 3 isolates were significantly (P < 0.05) more sensitive to ionizing radiation than the nalidixic acid-sensitive (NalS) parent strains in both systems. D10 values (the amount of ionizing radiation required to achieve 1 log10 reduction) determined in buffer for the parent strains ranged from 0.18 to 0.33 kGy, whereas for the NalR strains, D10 were approximately 0.10 kGy, a reduction of up to 69%. When evaluated on green leaf lettuce, the D10 for the NalS strains was approximately 0.18 kGy as opposed to 0.10 to 0.12 kGy for the NalR strains, a reduction of up to 45%. The D10 values obtained on lettuce were significantly different than those obtained in buffer for 4 of the 6 isolates examined. The magnitude of the increase in radiation sensitivity resulting from resistance to nalidixic acid varied among the strains tested and also varied depending on the suspending medium. These results suggest that the use of nalidixic acid resistance as a selective marker may result in significant overestimates of the antimicrobial efficacy of ionizing radiation against E. coli O157:H7. [source] Radiation Sensitivity and Recoverability of Listeria monocytogenes and Salmonella on 4 Lettuce TypesJOURNAL OF FOOD SCIENCE, Issue 9 2003B. A. NIEMIRAArticle first published online: 20 JUL 200 ABSTRACTListeria monocytogenes or Salmonella was inoculated onto Boston, Iceberg, Green leaf, and Red leaf lettuces. Samples were ,-irradiated, and the radiation sensitivity of the inoculated bacteria determined. Recovery of bacteria from nonirradiated leaf pieces was also measured. Although the radiation sensitivity of L. monocytogenes was not influenced by the associated lettuce type, Salmonella was significantly less sensitive on Green leaf lettuce than on Boston, Iceberg, or Red leaf lettuces. For each pathogen, the recoverability from inoculated leaf pieces was significantly different among the 4 lettuce types; the pattern of recovery of L. monocytogenes was distinct from that of Salmonella. The antimicrobial efficacy of irradiation on inoculated lettuce was influenced by relatively subtle differences between lettuce types. [source] Effect of selected antimicrobial compounds on the radiosensitization of Salmonella Typhi in ground beefLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2009M. Turgis Abstract Aims:, In this study, we extended our previous work to determine the efficiency of antimicrobial compounds in increase of relative radiosensitivity of Salmonella Typhi in medium fat ground beef (23% fat) by testing 41 different essential oils (EOs), oleoresins and food sauces. Methods and Results:, Ground beef samples inoculated with Salmonella Typhi (106 CFU g,1) were treated with each antimicrobial compound at a concentration of 0·5% (w/w). Then, the samples (25 g each) were packaged under air and irradiated in a 60Co irradiator at doses from 0 to 1·75 kGy. Radiosensitivity was evaluated by calculating relative radiation sensitivity, defined as the ratio of radiation D10 value in the absence/presence of antimicrobial compound. Conclusions:, Depending on the compound tested, the addition of antimicrobial compound decreased the D10 value of Salmonella Typhi, resulting in an increase of the radiation sensitivity up to more than four times. Among these antimicrobial compounds, Chinese cinnamon EO, clove EO and trans -cinnamaldehyde were most effective to increase the radiosensitivity of Salmonella Typhi in ground beef. Significance and Impact of the Study:, These observations demonstrate that some active compounds can function as radiosensitizers of Salmonella Typhi. [source] Gamma radiation sensitivity of the eggs, larvae and pupae of Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2008Abdurrahman Ayvaz Abstract BACKGROUND: This study focused on determining the minimal effective gamma radiation dose that prevents commodity damage caused by the Indian meal moth Plodia interpunctella (Hübner). The study was also designed to assess the effect of releasing either partially sterilized males alone or both partially sterilized males and females on the reproductive potential of P. interpunctella populations. RESULTS: The dose of radiation required to prevent larval emergence from irradiated eggs was 350 Gy, and the same dose was also required to prevent adult emergence from mature larvae. A dose of 300 Gy was not able to prevent adult emergence from irradiated pupae. The dose at which 100% sterility was achieved in treated females mated to treated males was 300 Gy for the parental generation of irradiated pupae. Fertility of the parental males from irradiated pupae was 48.17% at 300 Gy in treated males crossed with untreated females, but male progeny of irradiated male parents had a residual fertility of 11.06% at the same dose. CONCLUSION: F1 males from irradiated pupae were more sterile than parental males. To prevent larval emergence from irradiated eggs, a dose of 350 Gy is required. The same dose is required to prevent the larvae from reaching the adult stage. Copyright © 2008 Society of Chemical Industry [source] Overexpression of the cytoprotective protein clusterin decreases radiosensitivity in the human LNCaP prostate tumour modelBJU INTERNATIONAL, Issue 4 2003T. Zellweger The paper by Zellweger et al. builds on the continuing story of clusterin (TRPM-2) in the development and progression of prostate cancer. This group have published a series of papers on this protein, showing that it correlates with progression to androgen-independence and resistance to apoptosis. One of their recent papers has shown that ,knocking out' clusterin increases radiation sensitivity in prostate cancer cells. The current paper reports that increasing the expression of clusterin in LNCaP cells increases the cell's resistance to radiation-induced apoptosis. Manipulating identified survival proteins has important implications in preventing androgen-independent progression. Clusterin is such a survival protein and represents an important drug target in the near future. OBJECTIVE To evaluate the effect of clusterin overexpression on radiation-induced tumour growth rates and apoptosis in human prostate LNCaP cells, as prostate cancer cells are relatively resistant to radiation-induced apoptosis and local recurrences are common, but overexpression of the anti-apoptotic protein clusterin can accelerate progression to androgen-independence and to confer a chemoresistant phenotype in various prostate cancer models. MATERIALS AND METHODS Western blot analysis and immunohistochemistry were used to compare clusterin expression levels in parental (P) and clusterin-transfected (T) LNCaP cells in vitro and in vivo. The effects of radiation on clusterin-expression in both parental LNCaP/P and clusterin-transfected LNCaP/T tumours were analysed by Northern blot analysis. The cellular response to radiation was determined up to 3 weeks after irradiation using tetrazolium and re-growth assays, and cell-cycle analysis by flow cytometry. RESULTS Clusterin mRNA expression increased from undetectable to low levels in LNCaP/P tumours after radiation and more than three-fold in LNCaP/T tumours. Clusterin overexpression decreased the radiosensitivity in a time-dependent manner, reducing the extent of growth arrest and apoptosis by up to 54%. Re-growth assays showed that the improved survival rates of LNCaP/T cells after radiation did not change after 3 days, remaining constant over 3 weeks. CONCLUSIONS These results identify clusterin as a promoter of cell survival that may help mediate resistance to radiation-induced apoptosis. Furthermore, clusterin overexpression seems to provide an extended protection against radiation-induced cell cycle arrest and apoptosis. [source] 3142: Radiation-induced lens opacities: towards a new strategy to address the low dose risk research with the European network DoReMiACTA OPHTHALMOLOGICA, Issue 2010P GOURMELON In 2010, a Network of Excellence called DoReMi was launched by the EURATOM FP7 programme. DoReMi will act during the next six years as an operational tool for the development of a research platform devoted to low dose risk research in Europe. The research activities of DoReMi are implemented within three work packages: WP5, WP6, and WP7, which are respectively concerned with the shape of the dose effect relationship, individual radiation sensitivity and non-cancer effects. The overarching objective of WP7 is to implement a long-term, integrated approach involving several disciplines, namely, epidemiology, radiobiology and toxicology, for the purpose of risk evaluation for radiation-induced non-cancer effects. One of the operational objectives of the DoReMi WP7 consists of undertaking feasibility studies addressing the issues of vascular effects, lens opacities and cognitive effects. The presentation to be given will provide the assembly with (i) information about the European low dose risk research strategy; (ii) latest knowledge about the epidemiological evidence of radiation-induced lens opacities; (iii) information about the feasibility study of lens opacities to be launched in a group of interventional cardiologists (iv) most promising mechanistic hypotheses for the development of radiation-induced lens opacities recognizing that while posterior subcapsular cataracts are characteristic of an exposure to ionizing radiation, several sets of data suggest that the broader category of posterior cortical cataracts may also be regarded as radiation-associated. Eventually the presentation will discuss the issue of a threshold for the development of radiation-induced lens opacities and list the scientific questions raised by the radiation protection community to the vision and eye research community. [source] | ||||||||||||||||