88 research outputs found
Linee Guida per la garanzia di qualità nell’irradiazione corporea totale. Rapporto ISTISAN 02/39
No full textRadiobiological basis of hadrontherapy
No full textAfter a description of the rationale for the therapeutic use of charged hadrons, this paper briefly reviews the measured radiobiological properties of therapeutic hadron beams together with some relevant biophysics model aimed at their interpretation and at predicting the biological effects in mixed radiation fields.
The problem of deriving a “clinical” RBE from the “biological” one is also shortly described, considering separately the proton and carbon ions cases. For the former case the simplifying assumption of RBE=1.1 (and criticisms to it) currently adopted in general by the proton therapy Centres is described, while for the latter case the main two approaches (developed in Japan and in Germany) are outlined.
Finally, the importance of gaining a better knowledge in hadron radiobiology is addressed. This need is put into the perspective of the increasing number of hadrontherapy facilities in the world and in Italy in particular
Reduced Environmental Dose Rates Are Responsible for the Increased Susceptibility to Radiation‐Induced DNA Damage in Larval Neuroblasts of Drosophila Grown inside the LNGS Underground Laboratory
No full textA large amount of evidence from radiobiology studies carried out in Deep Underground Laboratories support the view that environmental radiation may trigger biological mechanisms that enable both simple and complex organisms to cope with genotoxic stress. In line with this, here we show that the reduced radiation background of the LNGS underground laboratory renders Drosophila neuroblasts more sensitive to ionizing radiation‐induced (but not to spontaneous) DNA breaks compared to fruit flies kept at the external reference laboratory. Interestingly, we demonstrate that the ionizing radiation sensitivity of flies kept at the LNGS underground laboratory is rescued by increasing the underground gamma dose rate to levels comparable to the low‐LET reference one. This finding provides the first direct evidence that the modulation of the DNA damage response in a complex multicellular organism is indeed dependent on the environmental dose rate
Low-radiation environment affects the development of protection mechanisms in V79 cells
No full textVery little is known about the influence of environmental radiation on living matter. In principle, important information can be acquired by analysing possible differences between parallel biological systems, one in a reference-radiation environment (RRE) and the other in a low-radiation environment (LRE). We took advantage of the unique opportunity represented by the cell culture facilities at the Gran Sasso National Laboratories of the Istituto Nazionale di Fisica Nucleare, where environment dose rate reduction factors in the underground (LRE), with respect to the external laboratory (RRE), are as follows: 103 for neutrons, 107 for directly ionizing cosmic rays and 10 for total γ-rays. Chinese hamster V79 cells were cultured for 10 months in both RRE and LRE. At the end of this period, all the cultures were kept in RRE for another 6 months. Changes in the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and spontaneous mutation frequency at the hypoxanthine–guanine phosphoribosyl transferase (hprt) locus were investigated. The results obtained suggest that environmental radiation might act as a trigger of defence mechanisms in V79 cells, specifically those in reference conditions, showing a higher degree of defence against endogenous damage as compared to cells grown in a very low-radiation environment. Our findings corroborate the hypothesis that environmental radiation contributes to the development of defence mechanisms in today living organisms/systems
Influence of a low background environment on biochemical and biological responses in V79 cells.
No full textWe present the results of an experiment aimed at comparing the effects of different background radiation environments on metabolism and responses to gamma-rays and cycloheximide of cultured mammalian cells. Chinese hamster V79 cells were maintained in exponential growth in parallel for up to 9 months at the Istituto Superiore di Sanità (ISS) and at the INFN-Gran Sasso underground Laboratory (LNGS) where exposure due to gamma-rays and to radon was reduced by factors of about 70 and 25, respectively. After 9 months the cells grown at the LNGS (cumulative gamma dose about 30 microGy, average radon concentration around 5 Bq/m(3)), compared to the cells grown at the ISS (cumulative gamma-ray dose about 2 mGy, average radon concentration around 120 Bq/m(3)), exhibited i). a significant increase of the cell density at confluence, ii). a significantly higher capacity to scavenge organic and inorganic hydroperoxides but a reduced scavenging capacity towards superoxide anions and iii). an increase in both the basal hprt mutation frequency and sensitivity to the mutagenic effect of gamma-rays. The cells grown at the LNGS also showed a greater apoptotic sensitivity starting at the third month of culture, that was no longer detected after 9 months. Overall, these data suggest a role of background ionizing radiation in determining an adaptive response, although they cannot be considered conclusiv
Influence of a low background radiation environment on biochemical and biological responses in V79 cells
No full textWe present the results of an experiment aimed at comparing the effects of different background radiation environments on metabolism and responses to gamma-rays and cycloheximide of cultured mammalian cells. Chinese hamster V79 cells were maintained in exponential growth in parallel for up to 9 months at the Istituto Superiore di Sanità (ISS) and at the INFN-Gran Sasso underground Laboratory (LNGS) where exposure due to gamma-rays and to radon was reduced by factors of about 70 and 25, respectively. After 9 months the cells grown at the LNGS (cumulative gamma dose about 30 microGy, average radon concentration around 5 Bq/m(3)), compared to the cells grown at the ISS (cumulative gamma-ray dose about 2 mGy, average radon concentration around 120 Bq/m(3)), exhibited i). a significant increase of the cell density at confluence, ii). a significantly higher capacity to scavenge organic and inorganic hydroperoxides but a reduced scavenging capacity towards superoxide anions and iii). an increase in both the basal hprt mutation frequency and sensitivity to the mutagenic effect of gamma-rays. The cells grown at the LNGS also showed a greater apoptotic sensitivity starting at the third month of culture, that was no longer detected after 9 months. Overall, these data suggest a role of background ionizing radiation in determining an adaptive response, although they cannot be considered conclusive
Induction and repair of DNA DSB as revealed by H2AX phosphorylation foci in human fibroblasts exposed to low-and high-LET radiation: Relationship with early and delayed reproductive cell death
No full textThe spatial distribution of radiation-induced DNA breaks within the cell nucleus depends on radiation quality in terms of energy deposition pattern. It is generally assumed that the higher the radiation linear energy transfer (LET), the greater the DNA damage complexity. Using a combined experimental and theoretical approach, we examined the phosphorylation-dephosphorylation kinetics of radiation-induced Î3-H2AX foci, size distribution and 3D focus morphology, and the relationship between DNA damage and cellular end points (i.e., cell killing and lethal mutations) after exposure to gamma rays, protons, carbon ions and alpha particles. Our results showed that the maximum number of foci are reached 30 min postirradiation for all radiation types. However, the number of foci after 0.5 Gy of each radiation type was different with gamma rays, protons, carbon ions and alpha particles inducing 12.64 ± 0.25, 10.11 ± 0.40, 8.84 ± 0.56 and 4.80 ± 0.35 foci, respectively, which indicated a clear influence of the track structure and fluence on the numbers of foci induced after a dose of 0.5 Gy for each radiation type. The Î3-H2AX foci persistence was also dependent on radiation quality, i.e., the higher the LET, the longer the foci persisted in the cell nucleus. The Î3-H2AX time course was compared with cell killing and lethal mutation and the results highlighted a correlation between cellular end points and the duration of Î3-H2AX foci persistence. A model was developed to evaluate the probability that multiple DSBs reside in the same gamma-ray focus and such probability was found to be negligible for doses lower than 1 Gy. Our model provides evidence that the DSBs inside complex foci, such as those induced by alpha particles, are not processed independently or with the same time constant. The combination of experimental, theoretical and simulation data supports the hypothesis of an interdependent processing of closely associated DSBs, possibly associated with a diminished correct repair capability, which affects cell killing and lethal mutation
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