Showing papers by "Giustina Simone published in 2002"
TL;DR: A role of background ionizing radiation in determining an adaptive response to γ-rays and cycloheximide is suggested, although they cannot be considered conclusive.
Abstract: We 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 Sanita (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.
54 citations
TL;DR: Differences were observed in the yield and spatial correlation, at a molecular size scale characteristic of loop dimensions, of the double-strand breaks induced by γ-rays and by light ions, which may have a role in the observed different cell response to these radiations.
Abstract: Purpose : To compare the results on DNA fragmentation induced in Chinese hamster V79 cells by various doses of γ-rays and low-energy protons and helium-4 ions. Materials and methods : V79 cells were irradiated as monolayers with monoenergetic protons and helium-4 ions; γ-rays were used as the reference radiation. DNA double-strand breaks were evaluated by calibrated pulsed-field gel electrophoresis using conditions covering the range 5.7 Mbp-23.1 kbp. Results : The fragment-counting method gave double-strand breaks yields and the relative biological effectiveness higher than those obtained by the fraction of activity released method. The frequency distribution of fragments showed that protons and helium ions induced more fragments below the Mbp region than did γ-rays at the same dose. The distributions for both the irradiated and non-irradiated samples clearly appeared to be non-random. Conclusion : Differences were observed in the yield and spatial correlation, at a molecular size scale characteristic of...
44 citations
TL;DR: Use of cellular systems capable of undergoing in vitro differentiation can give useful information on the basic mechanisms of cellular radiation sensitivity and preliminary data recently obtained on radiation induced DNA fragmentation as a function of radiation quality are presented.
Abstract: Use of cellular systems capable of undergoing in vitro differentiation can give useful information on the basic mechanisms of cellular radiation sensitivity. During differentiation the cellular organisation, including the nuclear structure and the intracellular concentration of several compounds and enzymes change drastically. Accordingly, radiation response to ionising radiation is also expected to change. The human proerythroblastoid cell line K562 can be induced to pseudoerythroid differentiation. This process has been characterised and studies have been carried out on DNA single strand break and double strand break induction and repair before and after differentiation commitment. Rejoining studies have been performed for both types of damage and correct double strand break rejoining has been also measured in particular genomic locations. An overview is presented of these results together with preliminary data recently obtained on radiation induced DNA fragmentation as a function of radiation quality.
1 citations