Radiation, response

In practice, o2one concentrations obtained by commercial uv devices ate low. This is because the low intensity, low pressure mercury lamps employed produce not only the 185-nm radiation responsible for o2one formation, but also the 254-nm radiation that destroys o2one, resulting in a quantum yield of - 0.5 compared to the theoretical yield of 2.0. Furthermore, the low efficiency (- 1%) of these lamps results in a low o2one production rate of 2 g/kWh (100). 

The U.S. - Australia Symposium on Radiation Effects on Polymeric Materials contained research presentations on fundamental radiation chemistry and physics as well as on technological applications of polymer irradiation. This paper represents a hybrid contribution of these two areas, examining a field of extensive technological importance. Spin casting of radiation sensitive polymer resists for microelectronic fabrication was studied using photophysical techniques that are sensitive to the fundamental radiation response in the ultraviolet range. 

Other localization methods rely on mass spectrometry in vaporized parts of the sample such as secondary ion mass spectrometry, SIMS, and other techniques [77, 78]. Here, atomic boron is detected. In addition, the specific electron shell energy of boron (usually the K shell) can be used for visualization [66, 79]. A combination of quantitative techniques with suboptimal spatial resolution and the high-resolution detection methods can give an indication about the radiation response to be expected. All these techniques require, however, that the compound in ques-... 

Tusher VG, Tibshirani R, Ghu G. 2001. Significance analysis of microarrays applied to ionizing radiation response. Proc Natl Acad Sci USA 98 5116. 

Resist materials can be classified as positive or negative on the basis of their radiation response as described in Section 3.1 and illustrated in Figure 1. Both resist types can be subdivided into two categories depending upon the basic nature of their design 1) one-component systems and 2) two-component systems (see Figure 2). One-component systems are polymers that combine radiochemical reactivity with etch resistance and film-forming characteristics. In two component systems, the resist is formulated from an... 

Chastagner P, Merlin JL, Marchal C, et al. In vivo potentiation of radiation response by topotecan in human rhabdomyosarcoma xenografted into nude mice. Clin Cancer Res 2000 6(8) 3327-3333. 

Kim JH, KimSH, Kolozsvary A, KhilMS. Potentiation of radiation response in human carcinoma cells in vitro and murine fibrosarcoma in vivo by topotecan, an inhibitor of DNA topoisomerase I. Int J Radiat Oncol Biol Phys 1992 22(3) 515-518. 

These same authors also report a dose-dependent increase in the apoptotic rate after the administration of gemcitabine (33), which they believe correlates with the elimination of the more radioresistant S phase population of cells and redistribution of the remaining cells into more radiosensitive compartments of the cell cycle. They also report in another study that reoxygenation of the resistant hypoxic fraction of tumor cells is also a mechanism for the action of gemcitabine (34). Therefore, elimination of these S phase tumor cells may aid the radiation response by not only causing cell cycle synchronization but also by leading to reoxygenation of hypoxic cells. 

Huang SM, Harari PM. Modulation of radiation response after epidermal growth factor receptor blockade in squamous cell carcinomas inhibition of damage repair, cell cycle kinetics, and tumor angiogenesis. Clin Cancer Res 2000 6 2166-2174. 

Lee CG, Heijn M, di Tomaso E, et al. Anti-vascular endothelial growth factor treatment augments tumor radiation response under normoxic or hypoxic conditions. Cancer Research 2000 60(19) 5565-5570. 

M. Nordsmark, M. Overgaard, J. Overgaard, Pretreatment oxygenation predicts radiation response in advanced squamous cell carcinoma of the head and neck, Radiother. Oncol. 41(1) (1996) 31-39. 

J.A. Raleigh, S.C. Chou, G.E. Arteel, M. Horsman, Comparison among pimonidazole binding oxygen electrode measurements, and radiation response in C3H mouse tumors, Radiat. Res. 151 (1999) 580-589. 

D. Zhao, A. Constantinescu, C.H. Chang, E.W. Hahn, R.P. Mason, Correlation of tumor oxygen dynamics with radiation response of the dunning prostate R3327-HI tumor, Radiat. Res. 159 (2003) 621-631. 

A.W. Fyles, M. Milosevic, R. Wong, M.C. Kavanagh, M. Pintile, A. Sun, W. Chapman, W. Levin, L. Manchul, T.J. Keane, R.P. Hill, Oxygenation predicts radiation response and survival in patients with cervix cancer, Radiother. Oncol. 48 (1998) 149-156. 

M. Hockel, K. Schlenger, B. Aral, M. Mitze, U. Schaffer, P. Vaupel, Hypoxia and radiation response in human tumors. Semi. Radiat. Oncol. 6 (1996) 3-9. 

Bjermer, and R. Henriksson. Effects of tobacco smoke on tumor growth and radiation response of dunning R3327 prostate adenocarcinoma in rats. Prostate 2000 42(4) 253-259. 

Hydrated aluminum oxide is a preferred flame refardanf fhaf liberates its water of hydrafion when exposed to flames, in contrast to chlorinated materials, which give off toxic gases as by-products. The paraffin oil is a processing aid that enhances the ability to extrude such materials. The silane is a coupling agent that improves the interaction between the polymers and the aluminum trihydrate. Trimethylolpropane trimethacrylate (TMPT) enhances the radiation response. 

A replication-deficient adenovirus has been used to deliver a gene construct, which contains within its promoter region a radiation-responsive element. Upon irradiation with conventional doses of X rays, this construct initiates transcription of the gene coding for the toxic cytokine, tumor necrosis factor-a (35). The above is an exquisite example of how emerging delivery and gene therapies are fast blurring the distinction between an active and an excipient (Fig. 3D). 

Quintiliani M (1983) Cellular thiols and radiation response. In Balzani V (ed) Baxendale memorial symposium. Lo Scarabeo, Bologna, pp 81-108... 

Table 12.22. Non-protein sulfhydryl (NPSH) and glutathione (GSH) content (pmol/mg protein) of normal (GSH+/+) and GSH-deficient (GSH / ) mammalian cells and the radiation response of these cells. (Revesz 1985) ...

The radiation response of cells from a GSH-synthetase-deficient patient and its clinically healthy brother are compared in Table 12.22. There, it is seen that the GSH deficiency results in a lower OER both of survival and SSB formation. This is largely due to a reduction of GSH, since the other non-protein sulfhy-dryls (NPSH) are not markedly suppressed in this mutant. The efficiency of GSH has been attributed to its particular spatial distribution, since exogenous thiols (here cysteamine) cannot substitute for this. Other sensitizers such as misonidazole (see below) behave similar as O2 with respect to SSB formation in these two cell lines. 

JennerTJ, Fulford J, O Neill P (2001) Contribution of base lesions to radiation-induced clustered DNA damage implication for models of radiation response. Radiat Res 156 590-593 Jeppesen C, Buchardt O, Flenriksen U, Nielsen PE (1988) Photocleavage of DNA photofootprinting of E. coli RNA polymerase bound to promoter DNA by azido-9-acridinylamines. Nucleic Acids Res 16 5755-5770... 

Que BG, Downey KM, So AG (1980) Degradation of deoxyribonucleic acid by a 1,10-phenanthroline-copper complex the role of hydroxyl radicals. Biochemistry 19 5987-5991 Quintiliani M (1983) Cellular thiols and radiation response. In Balzani V (ed) Baxendale Memorial Symposium. Lo Scarabeo, Bologna, pp 81-108... 

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