Comments from the New Editor: Perspectives on Radiation Research

International Journal of Radiation Biology, 1989

Radiation Research, 2014

Contemporary radiotherapy is bases in the considerable part for knowledge about the radiation physics and basic radiobiological mechanisms in the tumor tissues and healthy tissues. Advan- ce in molecular biology and radiobiology of the radiation ionizing, he sells to the better un- derstanding of the mechanisms early and late effects of treatment. The investigations of new diagnostic and therapeutic methods the same appear the possibility in the treatment of tumours. The work describes molecular and tissue mechanisms, the efficacies of the radiation ionizing on the neoplasmic tumor.

Stem Cells, 1995

CURRENT SCIENCE- …, 2001

msf.lu.se

Purposes: To review research progress on the molecular mechanisms of low dose ionizing radiation (LDIR)-induced hormesis, adaptive responses, radioresistance, bystander effects, and genomic instability in order to provide clues for therapeutic approaches to enhance biopositive effects (defined as radiationinduced beneficial effects to the organism), and control bionegative effects (defined as radiation-induced harmful effects to the organism) and related human diseases. Conclusions: Experimental studies have indicated that Ataxia telangiectasia-mutated (ATM), extracellular signal-related kinase (ERK), mitogen-activated protein kinase (MAPK), phospho-c-Jun NH 2 -terminal kinase (JNK) and protein 53 (P53)-related signal transduction pathways may be involved in LDIR-induced hormesis; MAPK, P53 may be important for adaptive response; ATM, cyclooxygenase-2 (COX-2), ERK, JNK, reactive oxygen species (ROS), P53 for radioresistance; COX-2, ERK, MAPK, ROS, tumor necrosis factor receptor alpha (TNFa) for LDIR-induced bystander effect; whereas ATM, ERK, MAPK, P53, ROS, TNFa-related signal transduction pathways are involved in LDIR-induced genomic instability. These results suggest that different manifestations of LDIR-induced cellular responses may have different signal transduction pathways. On the other hand, LDIR-induced different responses may also share the same signal transduction pathways. For instance, P53 has been involved in LDIR-induced hormesis, adaptive response, radioresistance and genomic instability. Current data therefore suggest that caution should be taken when designing therapeutic approaches using LDIR to induce beneficial effects in humans. Int J Radiat Biol Downloaded from informahealthcare.com by National University of Singapore on 08/22/14 For personal use only. Int J Radiat Biol Downloaded from informahealthcare.com by National University of Singapore on 08/22/14 For personal use only. References Ainsbury EA, Bouffler SD, Dörr W, Graw J, Muirhead CR, Edwards AA, Cooper J. 2009. Radiation cataractogenesis: A review of recent studies. Radiat Res 172:1-9. Albanese J, Dainiak N. 2000. Ionizing radiation alters Fas antigen ligand at the cell surface and on exfoliated plasma membranederived vesicles: Implications for apoptosis and intercellular signaling. Radiat Res 153:49-61. Amsel J, Waterbor JW, Oler J, Rosenwaike I, Marshall K. 1982. Relationship of site-specific cancer mortality rates to altitude. Carcinogenesis 3:461-465. Aurengo A, Averbeck D, Bonnin A, LeGuen B, Masse R, Monier R, Tubiana M, Valleron AJ, de Vathaire F. 2005. Dose-effect relationships and estimation of the carcinogenic effects of low doses of ionizing radiation. Paris: Academies of Sciences and Medicine. Azzam EI, de Toledo SM, Raaphorst GP, Mitchel RE. 1996. Low-dose ionizing radiation decreases the frequency of neoplastic transformation to a level below the spontaneous rate in C3H 10T1/2 cells. Radiat Res 146:369-373. Int J Radiat Biol Downloaded from informahealthcare.com by National University of Singapore on 08/22/14 For personal use only.

Occupational Medicine, 2006

Current understanding of risk associated with low-dose radiation exposure has for many years been embedded in the linear-no-threshold (LNT) approach, based on simple extrapolation from the Japanese atomic bomb survivors. Radiation biology research has supported the LNT approach although much of this has been limited to relatively high-dose studies. Recently, with new advances for studying effects of low-dose exposure in experimental models and advances in molecular and cellular biology, a range of new effects of biological responses to radiation has been observed. These include genomic instability, adaptive responses and bystander effects. Most have one feature in common in that they are observed at low doses and suggest significant non-linear responses. These new observations pose a significant challenge to our understanding of low-dose exposure and require further study to elucidate mechanisms and determine their relevance.

Springer eBooks, 2022

Learning Objectives 3.1.1 Carbohydrates Carbohydrates are hydrated organic molecules consisting of carbon (C), hydrogen (H), and oxygen (O), characterized by the formula C x (H 2 O) y , where x and y denote the numbers of carbon or water in the molecule. Chemically, most carbohydrates are polyhydroxy aldehydes, ketones, alcohols, and acids, which can polymerize, form connected chains of molecules, and, therefore, become more complex [2]. In biological media, such as cells, some carbohydrates are a major energy source for all non-photosynthetic organisms (e.g., glycogen), and others have vital structural functions (e.g., chitin, cellulose) or are essential components of RNA, DNA, and biochemical cofactor synthesis (e.g., adenosine mono/ di/triphosphate). Investigations of ionization damage to carbohydrates were done mainly in the fields of food and DNA [3]. Food irradiation can be used to extend shelf life (0.5-3.0 kGy), to inhibit sprouting (0.03-0.12 kGy), for insect disinfestation (0.2-0.8 kGy) and parasite disinfestation (0.1-3.0 kGy), and to eliminate pathogenic bacteria that do not form spores (1.5-7.0 kGy). In this context, it is important to know the chemical transformations occurring at a molecular level, including carbohydrates, that might have an adverse impact on the nutritional, sensory, or functional state of food [4]. In DNA, the sugar moiety plays an important role in the radiation-induced strand breaking process, even if not all the carbohydrate alterations are implied [3]. Model molecules of carbohydrates, such as ethylene glycol, glycerol, and glucose, were used to understand radiation products yielded from carbohydrates. Furthermore, they were used to study the formation of radicals via electron spin resonance (ESR) and electron paramagnetic resonance (EPR) or molecular products via high-performance liquid chromatography-mass spectrometry (HPLC-MS 2) [4]. The radiolysis of carbohydrates in aqueous system is pH dependent and occurs mainly by an indirect interaction of hydroxyl radical (°OH) with C-H bonds producing carbohydrate radicals. In contrast, carbohydrates react slowly with superoxide radicals (coming from solvated electrons) and scarcely with °H radicals [3, 4]. The carbohydrate radicals readily react with molecular oxygen or experience dismutation, dimerization, and elimination of alcohol or water (the most ubiquitous). Thus, radiolysis of carbohydrate inside the DNA molecule can lead to a degradation of the sugar structure and a loss of the base. Box 3.1 In a Nutshell: Radiolysis Products with Carbohydrates, Proteins and Lipids Box 3.7 In a Nutshell: Importance of Chromatin Architecture Box 3.10 In a Nutshell: Consequences of DNA Damage Misrepair and Unrepair

Annals of Biomedical Engineering, 2008

Molecular mechanisms for the gamma-ionizing radiation (IR) resistance of human prostate cancer cells, PC-3, are not quite clear. Since the low-LET-IR effects are primarily manifested by the generation of reactive oxygen species (ROS), the IR-induced expressions both of ROSmetabolizing antioxidant enzymes, such as Mn-and CuZn superoxide dismutases (SODs) and catalase (Cat), and of the transcriptional nuclear factor-kappaB (NF-jB) were explored. A substantial increase in the concentrations of SODs was observed in the cells irradiated by 10 and 20 Gy relative to those irradiated by 0 and 2 Gy, while the Cat and NF-jB expressions were found to be fairly stable. A system biology model was developed to shed more light on how MnSOD affects the biological state of cells depending upon the production of H 2 O 2 . By raising the initial presence of MnSOD in the 0.7-10 lM concentration range, the timedependent concentrations of H 2 O 2 for various initial levels of MnSOD were contrasted. The radioresistance of PC-3 cells is suggested to be associated with the positive, feed-forward vicious circle established between the H 2 O 2 -mediated elevation of MnSOD expression.