Biomedical subjects

G Simone

Publications and source records attributed to G Simone.

At least 19 recordsLinked to original sources

PubMed2006

DNA fragments induction in human fibroblasts by radiations of different qualities.

Experimental data on DNA double strand break (DSB) induction in human fibroblasts (AG1522), following irradiation with several radiation qualities, namely gamma rays, 0.84 MeV protons, 58.9 MeV u(-1) carbon ions, iron ions of 115 MeV u(-1), 414 MeV u(-1), 1 GeV u(-1), and 5 GeV u(-1), are presented. DSB yields were measured by calibrated Pulsed Field Gel Electrophoresis in the DNA fragment size range 0.023-5.7 Mbp. The DSB yields show little LET dependence, in spite of the large variation of the latter among the beams, and are slightly higher than that obtained using gamma rays. The highest yield was found for the 5 GeV u(-1) iron beam, that gave a value 30% higher than the 1 GeV u(-1) iron beam. A phenomenological method is used to parametrise deviation from randomness in fragment size spectra.

Cells, Cultured↗

PubMed2006

A 244Cm irradiator for protracted exposure of cultured Mammalian cells with alpha particles.

A 244Cm alpha-particle irradiator was designed and constructed for radiobiological studies where protracted exposure at a low dose rate of cultured mammalian cells is required. It allows irradiation of a cell monolayer attached to the Mylar bottom of a specially designed Petri dish of 56 mm diameter (approximately 25 cm(2) area). The irradiator is based on a 20-mm-diameter stainless steel chamber containing a 148 kBq 244Cm source. The chamber, flushed with helium gas at a pressure kept slightly above the external pressure, is inserted into a cell incubator where temperature and CO2 concentration are controlled. Spectrometric and dosimetric characterization of the irradiator was carried out by means of an ion-implanted-silicon charged-particle detector, CR39 detectors, and Monte Carlo simulations with the TRIM code. Average LET of particles incident on the cells at the center of the Petri dish was evaluated to be 120 keV microm(-1) at 59 mm from the source, and the average dose rate was 5.69 x 10 Gy s(-1), with +12% and -8% variations at the center and the edge, respectively. The irradiator has been successfully tested and used for several experiments involving 16-d exposure of human fibroblasts monolayers.

Alpha Particles↗

PubMed2006

Decommissioning procedures for an 11 MeV self-shielded medical cyclotron after 16 years of working time.

The present article describes the decommissioning of a compact, self-shielded, 11 MeV medical cyclotron. A Monte Carlo simulation of the possible nuclear reactions was performed in order to plan the decommissioning activities. In the course of the cyclotron dismantling, cyclotron components, shields, and floor concrete samples were measured. Residual activities were analyzed with a Ge(Li) detector and compared with simulation data. Doses to staff involved in the decommissioning procedure were monitored by individual TL dosimeters. The simulations identified five radioactive nuclides in shields and floor concrete: 55Fe and 45Ca (beta emitters, total specific activity: 2.29 x 10(4) Bq kg) and 152Eu, 154Eu, 60Co (gamma emitters, total specific activity: 1.62 x 10(3) Bq kg-1). Gamma-ray spectrometry confirmed the presence of gamma emitters, corresponding to a total specific activity of 3.40 x 10(2) Bq kg-1. The presence of the radioisotope 124Sb in the lead contained in the shield structure, corresponding to a simulated specific activity of 9.38 x 10(3) Bq kg-1, was experimentally confirmed. The measured dose from external exposure of the involved staff was <20 muSv, in accordance with the expected range of values between 10 and 20 muSv. The measured dose from intake was negligible. Finally, the decommissioning of the 11 MeV cyclotron does not represent a risk for the involved staff, but due to the presence of long-lived radioisotopes, the cyclotron components are to be treated as low level radioactive waste and stored in an authorized storage area.

Computer Simulation↗

PubMed2005

DNA DSB induced by iron ions in human fibroblasts: LET dependence and shielding efficiency.

This paper reports on DNA DSB induction in human fibroblasts by iron ions of different energies, namely 5, 1 GeV/u, 414 and 115 MeV/u, in absence or presence of different shields (PMMA, Al and Pb). Measure of DNA DSB was performed by calibrated Pulsed Field Gel Electrophoresis using the fragment counting method. The RBE-LET relationships for unshielded and shielded beams were obtained both in terms of dose average LET and of track average LET. Weak dependence on these parameters was observed for DSB induction. The shielding efficiency, evaluated by the ratio between the cross sections for unshielded and shielded beams, depends not only on the shield type and thickness, but also on the beam energy. Protection is only observed at high iron ions energy, especially at 5 GeV/u, where PMMA shield gives higher protection compared to Al or Pb shields of the same thickness expressed in g/cm2.

Aluminum↗

PubMed2005

DNA DSB induced in human cells by charged particles and gamma rays: experimental results and theoretical approaches.

PURPOSE: To quantify the role played by radiation track structure and background fragments in modulating DNA fragmentation in human cells exposed to gamma-rays and light ions. MATERIALS AND METHODS: Human fibroblasts were exposed in vitro to different doses (in the range from 40 - 200 Gy) of (60)Co gamma-rays and 0.84 MeV protons (Linear Energy Transfer, LET, in tissue 28.5 keV/microm). The resulting DNA fragments were scored under two electrophoretic conditions, in order to optimize separation in the size ranges 0.023 - 1.0 Mbp and 1.0 - 5.7 Mbp. In parallel, DNA fragmentation was simulated both with a phenomenological approach based on the "generalized broken-stick" model, and with a mechanistic approach based on the PARTRAC (acronym of PARticle TRACk) Monte Carlo code (1.32 MeV photons were used for the simulation of (60)Co gamma-rays). RESULTS: For both gamma-rays and protons, the experimental dose response in the range 0.023 - 5.7 Mbp could be approximated as a straight line, the slope of which provided a yield of (5.3 +/- 0.4) x 10(-9) Gy(-1) bp(-1) for gamma-rays and (7.1 +/- 0.6) x 10(-9) Gy(-1) bp(-1) for protons, leading to a Relative Biological Effectiveness (RBE) of 1.3 +/- 0.2. From both theoretical analyses it appeared that, while gamma-ray data were consistent with double-strand breaks (DSB) random induction, protons at low doses showed significant deviation from randomness, implying enhanced production of small fragments in the low molecular weight part of the experimental range. The theoretical analysis of fragment production was then extended to ranges where data were not available, i.e. to fragments larger than 5.7 Mbp and smaller than 23 kbp. The main outcome was that small fragments (<23 kbp) are produced almost exclusively via non-random processes, since their number is considerably higher than that produced by a random insertion of DSB. Furthermore, for protons the number of these small fragments is a significant fraction (about 20%) of the total number of fragments; these fragments remain undetected in these experiments. Calculations for 3.3 MeV alpha particle irradiation (for which no experimental data were available) were performed to further investigate the role of fragments smaller than 23 kbp; in this case, besides the non-random character of their production, their number resulted to be at least as much as half of the total number of fragments. CONCLUSION: Comparison between experimental data and two different theoretical approaches provided further support to the hypothesis of an important role of track structure in modulating DNA damage. According to the theoretical approaches, non-randomness of fragment production was found for proton irradiation for the smaller fragments in the experimental size range and, in a significantly larger extent, for fragments of size less than 23 kbp, both for protons and alpha particles.

Cells, Cultured↗

PubMed2004

DNA fragmentation induced by Fe ions in human cells: shielding influence on spatially correlated damage.

Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used gamma rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by gamma rays in the size range 1-23 kbp; (3) a non-random DNA DSB induction by Fe ions.

Cell Line↗

PubMed2004

DNA fragmentation in V79 cells irradiated with light ions as measured by pulsed-field gel electrophoresis. II. Simulation with a generalized broken stick model.

PURPOSE: To characterize the differences among the experimental DNA fragmentation spectra induced in Chinese hamster V79 cells by gamma-rays, low-energy protons and alpha-particles through the use of a phenomenological model. MATERIALS AND METHODS: A model of DNA fragmentation was developed as a generalization of the broken-stick model, in which the double-strand breaks induced by radiation were considered randomly placed, but in which the manifestly non-random fragmentation of the control sample was fully taken into account and considered as the initial fragment distribution. Further, an analytical method was introduced that allowed an evaluation of the deviation from randomness of the fragmentation induced by radiation. RESULTS: The analysis of the experimental distribution of DNA fragments showed that there was a progressive departure from randomness in radiation-induced fragmentation going from gamma-rays to protons and then to alpha-particles. This deviation was characterized by an enhanced induction of fragments, and therefore by a larger correlation of double-strand breaks, in the experimental range of lower molecular weights. CONCLUSION: The analysis shows that low-energy light ions induce DNA fragmentation, at the loop level of the chromatin organization, that can be significantly non-random. The same analysis can readily be applied at different length scales, and thus it could offer a basis for the study of the link between DNA damage, correlated at various spatial scales and biological end-points.

Alpha Particles↗

PubMed2003

[Expression of steroid receptors and DNA synthesis in male breast cancer].

Using a double-labeling immunocytochemical-autoradiographic assay we studied 18 male breast carcinomas to evaluate the cell kinetic and receptor status in neoplastic cells during S-Phase and to detect possible differences with respect to 21 female breast cancers, from a previously, published study. In male breast cancer, the tumor receptor content and ER/PgR expression in neoplastic cells during S-Phase was higher (p = 0.01) than that in corresponding female tumor while tumoral cell proliferation was lower, but not significantly. In the previous reported study on female breast cancer we demonstrated that proliferative activity was higher in receptor negative cell population both for ER and PgR. Conversely, in male tumor, that difference was only present in relation to the expression of PgR: in fact, the proliferative activity was higher in PgR negative than in PgR positive cells (Anova Test: p = 0.04) while no difference was evidenced between ER negative versus ER positive cells. Moreover, the arrest of DNA synthesis, expressed as percentage of cells without 3H-Tdr labeling, was not related to either the ER or PgR expression, while in female breast cancer it was higher in PgR positive than ER positive cell population. Our data confirmed differences between males and females regarding the receptor status and cell cycle S-Phase in breast cancer. The poorer prognosis of the male breast carcinoma might be related to ineffective therapies which do not consider these differences in the biological profile of the male tumor. The Authors indicate that prognostic and predictive tissutal markers, detected by immunocytochemical methods and useful for therapeutic programming in the female breast cancer have a different significance in the male breast cancer and stress the need for different therapeutic strategies specific for male breast cancer.

Adult↗

PubMed2002

Influence of a low background radiation environment on biochemical and biological responses in V79 cells.

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 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.

Air Pollution, Indoor↗

PubMed2002

DNA fragmentation in V79 cells irradiated with light ions as measured by pulsed-field gel electrophoresis. I. Experimental results.

PURPOSE: To compare the results on DNA fragmentation induced in Chinese hamster V79 cells by various doses of gamma-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; gamma-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 gamma-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 loop dimensions, of the double-strand breaks induced by gamma-rays and by light ions. These effects may have a role in the observed different cell response to these radiations.

Animals↗

PubMed2002

Induction and repair of DNA damage in human cells at different stages of differentiation.

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.

Cell Differentiation↗

PubMed2002

mdm2-p53 Interaction: lack of correlation with the response to 5-fluorouracil in advanced colorectal cancer.

OBJECTIVE: We investigated the relevance of mdm2 and p53 primary tumour expression to the clinical outcome of a consecutive series of advanced colorectal cancer patients treated with a 5-fluorouracil-based chemotherapy. METHODS: The expression of p53 and mdm2 was analyzed by an immunohistochemical assay in 80 formalin-fixed paraffin embedded primary tumour samples and related to the clinical response to 5-fluorouracil therapy and to the prognosis of the patients. In a subgroup of 46 tumours, the apoptotic index (AI) as determined by the Tunel technique was also assessed. RESULTS: Nuclear immunostaining of p53 and mdm2 was present in 42 and 30% of the cases, respectively. No correlation was demonstrated between p53 and mdm2 expression (rs = -0.01; p > 0.05). With regard to the clinical outcome, no statistical association was demonstrated among p53 and mdm2 expression, AI, probability of clinical response to treatment, time to progression, or overall survival. The subgroup of patients with a p53-negative/mdm2-positive tumour showed a worse response rate (15%); however, mdm2-positive/AI-negative tumours showed a 0% (0/7) probability of a clinical response as compared with 30% (9/30) of the remaining tumour patient subgroups; this also translated in a significantly worse overall survival probability (p = 0.01 by log rank). CONCLUSIONS: The analysis of mdm2 expression does not add significant clinical information in colorectal cancers with a different p53 status. Conversely, further analysis of AI seems to give data of a promising prognostic-predictive value.

Adenocarcinoma↗

PubMed2001

Expression of apoptosis-related markers and clinical outcome in patients with advanced colorectal cancer.

The clinical relevance of bax and bcl-2 protein expression has been investigated in 84 patients with recurrent or metastatic colorectal cancer submitted to a chemotherapy regimen including methotrexate and fluorouracil/leucovorin. Cytoplasmic immunostaining of bax and bcl-2 was present in 65.5% and 38%, respectively, of the tumours. No association was found between bax and bcl-2 or between p53 and bax or bcl-2 protein expression. Moreover, the biomarkers were unrelated to patient and tumour characteristics known to affect the clinical outcome of colorectal cancer patients. In general, the apoptosis-related markers did not appear indicative of short- and long-term clinical response nor of prognosis. Bcl-2-negative lesions were more frequent among patients who reached an objective clinical response, which is in agreement with previously reported data regarding other tumour types. When the interrelationship between p53 and bax expression was examined, a better response rate (40%) was found for patients whose tumours did not express p53 and bax, and a better prognosis (2-year probability of overall survival 75%) for patients with p53-positive and bax-negative tumours. In the present series of patients with advanced colorectal cancer submitted to systemic chemotherapy we did not find a clear association between expression of apoptosis-related markers and clinical outcome, even in the subset of patients in which the apoptotic index as determined by the TUNEL approach was investigated.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2001

Failure of primary breast cancer neoangiogenesis to predict pattern of distant metastasis.

In the present study, the primary tumor neoangiogenesis characteristics of 81 stage IV previously untreated breast cancers with synchronous metastasis to different distant sites (10 patients with soft tissue metastases, 31 with bone metastases, and 40 with visceral metastases) were analyzed. The primary intratumor microvessel density was assessed by immunohistochemical assay on paraffin-embedded primary tumor samples, using a monoclonal anti-CD34 antibody. The mean primary intratumor microvessel density (at 400x fields) was 78 +/- 39 (SD) microvessels per field. The microvessel density was not significantly related to the main clinical/pathological features of the tumor (age, cytohistological grade, DNA ploidy, diameter, and receptor status). The percentage of tumor cases with high primary intratumor microvessel density (cut-off median value of the series 73 +/- 39 microvessels/field) did not significantly differ in patients with bone, soft tissue, or visceral metastatic disease. Analysis of clinical outcome showed a significantly shorter time to progression and overall survival for patients with visceral metastases (P<0.001 and P<0.0002 by log-rank, respectively). Presence of visceral metastases was confirmed to be the only independent prognostic factor related to a worse TTP (hazard risk 2.15, 95% confidence interval 1.14-4.03, P<0.02) and overall survival (hazard risk 1.81, 95% confidence interval 0.98-3.35, P<0.06) by multivariate analysis. In conclusion, the assessment of neoangiogenesis of primary breast cancer by CD34 expression does not provide information predictive of different distant sites of metastasis.

Adult↗

PubMed2001

DNA fragmentation in mammalian cells exposed to various light ions.

Elucidation of how effects of densely ionizing radiation at cellular level are linked to DNA damage is fundamental for a better understanding of the mechanisms leading to genomic damage (especially chromosome aberrations) and developing biophysical models to predict space radiation effects. We have investigated the DNA fragmentation patterns induced in Chinese hamster V79 cells by 31 keV/micrometer protons, 123 keV/micrometer helium-4 ions and gamma rays in the size range 0.023-5.7 Mbp, using calibrated Pulsed Field Gel Electrophoresis (PFGE). The frequency distributions of fragments induced by the charged particles were shifted towards smaller sizes with respect to that induced by comparable doses of gamma rays. The DSB yields, evaluated from the fragments induced in the size range studied, were higher for protons and helium ions than for gamma rays by a factor of about 1.9 and 1.2, respectively. However, these ratios do not adequately reflect the RBE observed on the same cells for inactivation and mutation induced by these beams. This is a further indication for the lack of correlation between the effects exerted at cellular level and the initial yield of DSB. The dependence on radiation quality of the fragmentation pattern suggests that it may have a role in damage repairability. We have analyzed these patterns with a "random breakage" model generalized in order to consider the initial non-random distribution of the DNA molecules. Our results suggest that a random breakage mechanism can describe with a reasonable approximation the DNA fragmentation induced by gamma rays, while the approximation is not so good for light ions, likely due to the interplay between ion tracks and chromatin organization at the loop level.

Animals↗

PubMed2001

Inactivation of human cells exposed to fractionated doses of low energy protons: relationship between cell sensitivity and recovery efficiency.

Within the framework of radiation biophysics research in the hadrontherapy field, split-dose studies have been performed on four human cell lines with different radiation sensitivity (SCC25, HF19, H184B5 F5-1 M10, and SQ20B). Low energy protons of about 8 and 20 keV/micron LET and gamma-rays were used to study the relationship between the recovery ratio and the radiation quality. Each cell line was irradiated with two dose values corresponding to survival levels of about 5% and 1%. The same total dose was also delivered in two equal fractions separated by 1.5, 3, and 4.5 hours. A higher maximum recovery ratio was observed for radiosensitive cell lines as compared to radioresistant cells. The recovery potential after split doses was small for slow protons, compared to low-LET radiation. These data show that radiosensitivity may not be related to a deficient recovery, and suggest a possible involvement of inducible repair mechanisms.

Cell Line↗

PubMed2001

nm23 expression in malignant ascitic effusions of serous ovarian adenocarcinoma.

The aim of this study was to evaluate nm23 expression as detected in malignant cells of neoplastic ascites and to verify its relationship with the presence of tissue nm23 and p53 in primitive neoplasia. Using an immunocytochemical assay with a specific anti-nm23 polyclonal antibody, nm23 expression was evaluated in ascitic effusions of 45 patients with ovarian serous adenocarcinoma and ascites in normal and/or hyperplastic mesothelial cells from 37 women with various neoplasms (12 ovarian neoplasms) free of malignant cells as controls. nm23 and p53 tissue expression was also detected in 21 corresponding tumor samples, including 11 bilateral lesions. nm23 was expressed in 57% of malignant effusions compared to 43% in controls: the two groups were not correlated. nm23 in effusions agreed with tissue expression (p=0.02) but a direct correlation was not demonstrated. The incidence of nm23 was more frequent in stage III than in stage IV disease (p=0.08) and was associated with mutated p53 expression (p=0.01). Using the Wilcoxon test for unpaired data, a higher incidence (p=0.05) of p53-positive tumors in bilateral cancers was found while a higher expression of nm23 in effusions of patients with monolateral lesions was observed (p=0.08). The presence of p53 was correlated with that of nm23 in both cytologic (p=0.005) and histological samples (p=0.01). Our findings, together with the diversity in biological behaviour present in various tumors, suggest that nm23 is a family of genes with differing biological functions which act as tumor-specific inhibiting factors within a complex process also involving other genes. Due to the analogies and correlations between nm23 and p53, the role of nm23 as a potential predictive factor of response to chemotherapy and in DNA repair is emphasized.

Aged↗

PubMed2001

DNA fragmentation induced in K562 cells by nitrogen ions.

This study was aimed at investigating the radiation induced DNA fragmentation pattern as a function of cellular differentiation and radiation quality. DNA double strand breaks (DSB) induced by gamma-rays were analyzed in K562 human proerythroblasts before (AP cells) and after (D cells) differentiation induction while DNA DSB induced by 125 keV/micrometers N-ions have been studied in AP cells. Pulsed-Field Gel Electrophoresis (PFGE) of cellular DNA was used to determine the DSB yield by analysis of the Fraction of Activity Released (FAR) and of the fragmentation pattern in a specific size range (5.7-0.225 Mbp). The results so far obtained show that the DSB induction by gamma-rays is different if evaluated with the FAR or with the fragmentation analysis. The DSB yield obtained with the former method is about 1.4 times higher in AP respect to D cells while the latter method indicates that more fragments are produced in D cells. Comparison between gamma-rays and N-ions in AP cells shows that no significant differences are detected by the FAR analysis; otherwise fragmentation analysis demonstrates a higher effectiveness of nitrogen ions.

Cell Differentiation↗