Aging-related decline in immunity is believed to be the main driver behind decreased vaccine efficacy and reduced resistance to infections in older adults. Unrepaired DNA damage is known to precipitate cellular senescence, which was hypothesized to be the underlying cause of certain age-related phenotypes. Consistent with this, some hallmarks of immune aging were more prevalent in individuals exposed to whole-body irradiation (WBI), which leaves no anatomical repository of undamaged hematopoietic cells. To decisively test whether and to what extent WBI in youth will leave a mark on the immune system as it ages, we exposed young male C57BL/ 6 mice to sublethal WBI (0.5-4 Gy), mimicking human survivor exposure during nuclear catastrophe. We followed lymphocyte homeostasis thorough the lifespan, response to vaccination, and ability to resist lethal viral challenge in the old age. None of the irradiated groups showed significant differences compared with mock-irradiated (0 Gy) animals for the parameters measured. Even the mice that received the highest dose of sublethal WBI in youth (4 Gy) exhibited equilibrated lymphocyte homeostasis, robust T-and B-cell responses to live attenuated West Nile virus (WNV) vaccine and full survival following vaccination upon lethal WNV challenge. Therefore, a single dose of nonlethal WBI in youth, resulting in widespread DNA damage and repopulation stress in hematopoietic cells, leaves no significant trace of increased immune aging in a lethal vaccine challenge model.

Xu, Yeming = 水熱法和熱蒸法製備硫化鋅納米结构的電子輻射損傷研究 / 徐業明. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 61-63). / Text in English; abstracts in English and Chinese. / Xu, Yeming = Shui re fa he re zheng fa zhi bei liu hua xin na mi jie gou de dian zi fu she sun shang yan jiu / Xu Yeming. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgment --- p.iii / List of Figures --- p.VII / Table of contents --- p.XI / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Background of electron beam irradiation --- p.4 / Chapter 2.1 --- Basic principles of electron beam irradiation --- p.4 / Chapter 2.1.1 --- Atomic displacement --- p.5 / Chapter 2.1.2 --- Electron beam sputtering --- p.7 / Chapter 2.1.3 --- Electron beam heating --- p.8 / Chapter 2.1.4 --- Radiolysis --- p.11 / Chapter Chapter 3 --- Instrumentation --- p.13 / Chapter 3.1 --- X-ray photoelectron spectroscopy (XPS) --- p.13 / Chapter 3.1.1 --- Basic principles --- p.13 / Chapter 3.1.2 --- Chemical shifts in x-ray photoelectron spectroscopy --- p.16 / Chapter 3.2 --- The principle of the Scanning Electron Microscopy (SEM) --- p.16 / Chapter 3. 3 --- Transmission Electron Microscope (TEM) --- p.19 / Chapter 3. 3.1 --- Principle of the TEM --- p.19 / Chapter 3.3.2 --- Electron specimen interaction in TEM --- p.21 / Chapter 3.3.3 --- Electron Diffraction --- p.22 / Chapter 3.3.4 --- Contrast --- p.22 / Chapter 3.4 --- Energy dispersive x-ray spectroscopy --- p.23 / Chapter 3.5 --- Elemental mapping using Electron Energy Loss Spectrometer (EELS) --- p.24 / Chapter Chapter 4 --- Structure Degradation of ZnS Nanomaterials Synthesized via Hydrothermal Method --- p.26 / Chapter 4.1 --- Experimental --- p.26 / Chapter 4.2 --- Structure degradation of ZnS nanotubes synthesized via hydrothermal method --- p.27 / Chapter 4.2.1 --- Chemical and structural characterization of the as-synthesized nanotubes --- p.27 / Chapter 4.2.2 --- Crystallinity and structural degradation of the nanosheet under the electron beam irradiation --- p.29 / Chapter 4.2.3 --- Nanotube structure degradation with different experimental parameters --- p.33 / Chapter 4.3 --- Structure degradation of ZnS nanosheets synthesized via hydrothermal method --- p.34 / Chapter 4.3.1 --- Chemical and morphological characteristics of the ZnS nanosheets --- p.34 / Chapter 4.3.2 --- Crystallinity and structural degradation of the nanosheet under the electron beam irradiation --- p.37 / Chapter 4.3.3 --- Nanosheet structure degradation with different experimental parameters --- p.41 / Chapter 4.3.4 --- Discussion on the damage mechanisms --- p.45 / Chapter Chapter 5 --- Structure Degradation of ZnS Nanobelts Synthesized via thermal evaporation Method --- p.48 / Chapter 5.1 --- Experimental --- p.48 / Chapter 5.2 --- Chemical and morphological characteristics of the ZnS nanobelts --- p.49 / Chapter 5.3 --- Crystallinity and structural degradation of the nanobelt under the electron beam irradiation --- p.50 / Chapter 5.4 --- Nanobelt structure degradation with different experimental parameters --- p.55 / Chapter 5.5 --- Discussion on the damage mechanisms --- p.56 / Chapter Chapter 6 --- Conclusion --- p.59 / References --- p.61

We report a novel fragmentation and functionalization method using a cyclic iminyl radical. Formation of this radical occurs by microwave heating under mild conditions and short reaction times. The reaction avoids the use of explosive or toxic radical initiators and propagating agents. This reaction is versatile, with the ability to install two functional groups that are ultimately derived from a ketone in the substrate precursor. A variety of radical traps capable of forming both carbon-carbon bonds and carbon-heteroatom bonds have been tested, and the products are obtained in good yields. We demonstrate the power of this reaction by functionalizing complex natural products.

歯科基礎医学会, 飯塚 正 = Tadashi Iizuka, 放射線照射ラットの抜歯創治癒過程に関する形態学的研究 = Morphological studies on the healing process of extraction wound in irradiated rats, 歯科基礎医学会雑誌, 26(3), SEP 1984, pp.745-785 / Hokkaido University (北海道大学) / 博士 / 歯学

Based on the author's MA thesis (84 leaves, University of British Columbia, 1982). / Includes bibliographical references. Also issued online.

The effect of electron beam irradiation upon microbiological quality and safety of fresh-cut tomatoes was studied. Preliminary studies were conducted to ensure reliability of the rifampicin-resistant strain versus the parent strain of Salmonella serovar Montevideo for use in this study. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Fresh tomatoes were obtained from a local supplier and then cut into cubes with stem scars being separated. Both cubes and stem scars were inoculated with a rifampicin- resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups and treated by electron beam irradiation at 0.0 kGy (control), 0.7 kGy or 0.95 kGy. The effect of electron beam irradiation was determined for Salmonella, yeast, mold, and lactic acid bacteria (LAB) populations as well as pH on tomato cubes and stem scars over a 15-day storage period at 4??C. Results indicated that while irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the microbial populations between treatments of 0.7 kGy or 0.95 kGy. Irradiation at either dose resulted in a significant reduction of Salmonella Montevideo when compared to the control, with an initial reduction of 1.8 and 2.2 log10 CFU/g on tomatoes for 0.7 kGy and 0.95 kGy, respectively. LAB, yeasts and molds were more resistant to the treatment than Salmonella. Populations present on stem scars and tomato cubes did experience some differences in log reductions, possibly due to the protective effect of the stem scar on microorganisms. However, no differences were detected between the two Salmonella serotypes in response to irradiation treatment. This study indicates that doses of irradiation greater than 1 kGy should be used in fresh-cut tomatoes to eliminate significant populations of pathogens, as well as to ensure the microbial quality of the product. Additional studies also need to be conducted to examine the effects of higher irradiation doses on the sensory qualities of fresh-cut tomatoes.

No description available.

No description available.

In the design of the food irradiation process, the knowledge of the radiation resistance of the target organism in a specific food commodity is required. The D10-value, the radiation dose needed to inactivate 90% of the microbial load in the food medium, is used to relate the amount of absorbed energy to the surviving bacterial population. Numerous experimental studies have been performed to determine the D10 values of several food-borne microorganisms irradiated under various conditions. Nevertheless, accurate predictions of D10 values of the pathogens in food products that have not been empirically examined cannot be made due to insufficient understanding of the biological response to radiation exposure. A theoretical model for the derivation of the D10-value has been proposed in this study to mechanistically assess the production of radiation-induced DNA damage by energetic electrons. The step-by-step Monte-Carlo simulation technique, which employs the detailed histories of the ionizing particles and the radiolytic species, was utilized. The effects of selected parameters including the genomic sequence, the type of DNA double strand break, the DNA damaging agents, the radical scavengers, the degree of dispersion of DNA molecules, and the number of genome equivalents were hypothetically investigated. The developed computational methodology as well as the results presented can be used as an analytical tool to evaluate the impact of ionizing radiation on cell survival.

The effect of electron beam irradiation upon microbiological quality and safety of fresh-cut tomatoes was studied. Preliminary studies were conducted to ensure reliability of the rifampicin-resistant strain versus the parent strain of Salmonella serovar Montevideo for use in this study. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Fresh tomatoes were obtained from a local supplier and then cut into cubes with stem scars being separated. Both cubes and stem scars were inoculated with a rifampicin- resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups and treated by electron beam irradiation at 0.0 kGy (control), 0.7 kGy or 0.95 kGy. The effect of electron beam irradiation was determined for Salmonella, yeast, mold, and lactic acid bacteria (LAB) populations as well as pH on tomato cubes and stem scars over a 15-day storage period at 4??C. Results indicated that while irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the microbial populations between treatments of 0.7 kGy or 0.95 kGy. Irradiation at either dose resulted in a significant reduction of Salmonella Montevideo when compared to the control, with an initial reduction of 1.8 and 2.2 log10 CFU/g on tomatoes for 0.7 kGy and 0.95 kGy, respectively. LAB, yeasts and molds were more resistant to the treatment than Salmonella. Populations present on stem scars and tomato cubes did experience some differences in log reductions, possibly due to the protective effect of the stem scar on microorganisms. However, no differences were detected between the two Salmonella serotypes in response to irradiation treatment. This study indicates that doses of irradiation greater than 1 kGy should be used in fresh-cut tomatoes to eliminate significant populations of pathogens, as well as to ensure the microbial quality of the product. Additional studies also need to be conducted to examine the effects of higher irradiation doses on the sensory qualities of fresh-cut tomatoes.