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We studied high temperature superconducting devices created by means of local nanostructuring with high-energy heavy-ion lithography. Linear arrays of alternate nanostructured and as-grown YBa2Cu3O7-x film regions are patterned on the microscale. The density of the induced nanostructures is tuned in such a way to locally depress the superconducting properties until a functional electromagnetic decoupling between nanostructured and as-grown microzones is achieved in suitable regions of the (B,T) phase diagram. Pilot prototypes engineered for operating as magnetic field detectors in harsh cryogenic environment are characterized by electric transport and surface morphology analysis at microscale and nanoscale. Sensitivity, linearity range, and bandwidth limits of the pilot prototype are established from electrical transport characterization. The morphological analysis reveals the salient aspects of the surface modifications occurring with high-fluence heavy-ion lithography. Radiation annealing experiments with 3.5 MeV proton energy were performed to check out the reliability of the prototype operating in harsh environments. These measurements demonstrate the robustness of this approach aimed at creating dissipative microscale units that are sensitive to magnetic fields in a continuous dissipationless superconducting material. [ABSTRACT FROM AUTHOR]

Experimental nanodosimetry aims to develop a new concept of radiation quality, based on the correlation between initial features of particle tracks and late biological outcome. A direct proportionality has been observed between the cumulative probability of measuring at least k ionisations within a nanometric volume and inactivation cross sections at specific survival levels. Based on this proportionality, physical quantities which are measurable at the nanometre level can be used to estimate the alpha and beta parameters of the linear-quadratic dose-response model, provided that two proportionality factors are determined in a reference radiation field. This work describes the procedure and first results applied to published data for V79 cell survival after irradiation with protons and carbon ions. [ABSTRACT FROM AUTHOR]

In the past two decades, a body of experimental evidences in vitro has shown the presence of a plethora of phenomena occurring after low-dose irradiation [including hypersensitivity and induced radioresistance (IRR), adaptive response, bystander effect (BE) and genomic instability], which might imply a non-linear behaviour of cancer risk curves in the low-dose region and question the validity of the linear no-threshold model for cancer risk assessment in such a dose region. In this framework, a systematic investigation have been undertaken on non-linear effects at low doses as a function of different radiation quality and cellular radiosensitivity and in terms of different biological end points. The present article reports the recent results on hyper-radiosensitivity and IRR and BE phenomena, in terms of clonogenic survival in V79 Chinese hamster cells and T98G human glioblastoma cells irradiated with protons and carbon ions with different energy, as a function of dose (and fluence). [ABSTRACT FROM AUTHOR]

The present investigation aimed to characterise the shape of dose-response curve and determining the frequency distribution of various aberration types as a function of dose and radiation quality in AG01522 primary human fibroblasts in the 0.1- to 1-Gy dose range. For this purpose, the cells were irradiated with 7.7 and 28.5 keV μm-1 low-energy protons, 62 keV μm-1 4He2+ ions (LNL Radiobiology facility) or X rays and samples collected for 24-colour mFISH analysis. X rays and 7.7 keV μm-1 protons displayed a quadratic dose-response curve solely for total and simple exchanges, whereas for high-linear energy transfer radiations, a linear dose-response curve was observed for all the aberration categories, with the exception of complex exchanges. [ABSTRACT FROM AUTHOR]

In the past two decades, a body of experimental evidences in vitro has shown the presence of a plethora of phenomena occurring after low-dose irradiation [including hypersensitivity and induced radioresistance (IRR), adaptive response, bystander effect (BE) and genomic instability], which might imply a non-linear behaviour of cancer risk curves in the low-dose region and question the validity of the linear no-threshold model for cancer risk assessment in such a dose region. In this framework, a systematic investigation have been undertaken on non-linear effects at low doses as a function of different radiation quality and cellular radiosensitivity and in terms of different biological end points. The present article reports the recent results on hyper-radiosensitivity and IRR and BE phenomena, in terms of clonogenic survival in V79 Chinese hamster cells and T98G human glioblastoma cells irradiated with protons and carbon ions with different energy, as a function of dose (and fluence). [ABSTRACT FROM AUTHOR]

The present investigation aimed to characterise the shape of dose--response curve and determining the frequency distribution of various aberration types as a function of dose and radiation quality in AG01522 primary human fibroblasts in the 0.1- to 1-Gy dose range. For this purpose, the cells were irradiated with 7.7 and 28.5 keV μm-1 low-energy protons, 62 keV μm-1 4He2+ ions (LNL Radiobiology facility) or X rays and samples collected for 24-colour mFISH analysis. X rays and 7.7 keV μm-1 protons displayed a quadratic dose--response curve solely for total and simple exchanges, whereas for high-linear energy transfer radiations, a linear dose--response curve was observed for all the aberration categories, with the exception of complex exchanges. [ABSTRACT FROM AUTHOR]

Purpose: To study EBT3 GafChromic film in low-energy protons, and for comparison purposes, in a reference 60Co beam in order to use it as a calibrated dosimetry system in the proton irradiation facility under construction within the framework of the Oncological Therapy with Protons (TOP)-Intensity Modulated Proton Linear Accelerator for RadioTherapy (IMPLART) Project at ENEA-Frascati, Italy. Methods: EBT3 film samples were irradiated at the Istituto Nazionale di Fisica Nucleare--Laboratori Nazionali di Legnaro, Italy, with a 5 MeV proton beam generated by a 7 MV Van de Graaff CN accelerator. The nominal dose rates used were 2.1 Gy/min and 40 Gy/min. The delivered dose was determined by measuring the particle fluence and the energy spectrum in air with silicon surface barrier detector monitors. A preliminary study of the EBT3 film beam quality dependence in low-energy protons was conducted by passively degrading the beam energy. EBT3 films were also irradiated at ENEA-National Institute of Ionizing Radiation Metrology with gamma radiation produced by a 60Co source characterized by an absorbed dose to water rate of 0.26 Gy/min as measured by a calibrated Farmer type ionization chamber. EBT3 film calibration curves were determined by means of a set of 40 film pieces irradiated to various doses ranging from 0.5 Gy to 30 Gy absorbed dose to water. An EPSON Expression 11000XL color scanner in transmission mode was used for film analysis. Scanner response stability, intrafilm uniformity, and interfilm reproducibility were verified. Optical absorption spectra measurements were performed on unirradiated and irradiated EBT3 films to choose the most sensitive color channel to the dose range used. Results: EBT3 GafChromic films show an under response up to about 33% for low-energy protons with respect to 60Co gamma radiation, which is consistent with the linear energy transfer dependence already observed with higher energy protons, and a negligible dose-rate dependence in the 2-40 Gy/min range. Short- and long-term scanner stabilities were 0.5% and 1.5%, respectively; film uniformity and reproducibility were better than 0.5%. Conclusions: The main purpose of this study was to implement EBT3 dosimetry in the proton low-energy radiobiology line of the TOP-IMPLART accelerator, having a maximum energy of 7 MeV. Low-energy proton and 60Co calibrated sources were used to investigate the behavior of film response vs to be written in italicum dose. The calibration in 5 MeV protons is currently used for dose assessment in the radiobiological experiments at the TOP-IMPLART accelerator carried out at that energy value. [ABSTRACT FROM AUTHOR]

Individual cell recognition is a relevant task to be accomplished when single-ion microbeam irradiations are performed. At INFN-LNL facility cell visualization system is based on a phase-contrast optical microscope, without the use of any cell dye. Unstained cells are seeded in the special designed Petri dish, between two mylar foils, and at present the cell recognition is achieved manually by an expert operator. Nevertheless, this procedure is time consuming and sometimes it could be not practical if the amount of living cells to be irradiated is large. To reduce the time needed to recognize unstained cells on the Petri dish, it has been designed and implemented an automated, parallel algorithm. Overlapping ROIs sliding in steps over the captured grayscale image are firstly pre-classified and potential cell markers for the segmentation are obtained. Segmented objects are additionally classified to categorize cell bodies from other structures considered as sample dirt or background. As a result, cell coordinates are passed to the dedicated CELLView program that controls all the LNL single-ion microbeam irradiation protocol, including the positioning of individual cells in front of the ion beam. Unstained cell recognition system was successfully tested in experimental conditions with two different mylar surfaces. The recognition time and accuracy was acceptable, however, improvements in speed would be useful. [ABSTRACT FROM AUTHOR]

Telomeres are the end of linear chromosomes, responsible for chromosome stability and cell viability. It is well known that radiations are able to induce chromosome instability but it has not yet been investigated whether telomere structure is affected by the radiation exposure and if radiations with different quality act in a different way on telomeres. The effect of radiations with different quality on telomere structure and chromosome instability was analysed in human primary fibroblasts exposed to X rays or low-energy protons (28.5 keV μm−1). Telomere length was evaluated at different harvesting times from 24 h up to 360 h (15 days), whereas chromosome instability was evaluated in terms of sister chromatid exchanges (SCEs) (48 h from irradiation) and chromosome painting (360 h from irradiation). Results indicated a delayed telomere lengthening 360 h after X-ray treatment, whereas protons were able to induce such a lengthening shortly from irradiation as well as at longer harvesting times. Data obtained from chromosome instability analysis indicated an increase of SCE frequency only after proton irradiation, but, on the contrary, at the longer harvesting time chromosome painting analysis displayed a higher frequency of aberrations after X-ray treatment, suggesting a role of selective process against highly damaged cells. [ABSTRACT FROM PUBLISHER]

A huge body of evidence about the hyper-radiosensitivity and induced radioresistance (HRS/IRR) phenomena and the bystander effect (BE) is reported in the literature, in many cell types and in terms of various biological endpoints, after high- and low-linear energy transfer irradiation. However, the mechanisms underlying these effects together with their inter-relationship, and the correlation of HRS/IRR and BE phenomena with radiation quality are not yet well established and elucidated. To study these phenomena, the radiation response of V79 cells has been evaluated in terms of cell survival after irradiation with broad beams of 7.7- and 28.5-keV μm−1 protons. HRS/IRR has been investigated also in terms of micronuclei and chromosomal aberration induction. The presence of BE has been investigated with a ‘partial shielding irradiation’ system, which prevents the irradiation of 35 % (on average) of the cell population. No clear evidence of HRS/IRR, nor of a significant BE response, can be identified in the low-dose region of V79 dose–response curves after proton irradiation of different energies. [ABSTRACT FROM PUBLISHER]

The efficacy of clodronate to reduce bone loss around uncemented stems after total hip arthroplasty (THA) was evaluated. Ninety-one patients operated with uncemented THA were randomized to receive either intramuscular clodronate at a dose of 100 mg weekly for 12 months or no treatment. Periprosthetic and contralateral bone mineral density (BMD) scans were performed and biochemical markers of bone turnover measured at baseline and at 3, 6, and 12 months. At month 12, with the exception of Gruen zones 4 and 5, patients treated with clodronate showed less bone loss at all zones, reaching statistical significance ( P < 0.05) in Gruen zones 2 and 6 (difference of 6.6 and 5.9%, respectively). Analysis of data according to gender revealed sex-related differences in bone loss and efficacy of treatment. After 12 months, the difference in bone loss between treated and untreated women in five out of seven Gruen zones ranged from 6.2 to 13.3% (SS at zones 2 and 6), whereas comparison between treated and untreated men showed no BMD differences in all zones ( P > 0.05). Median percent changes in serum levels of markers of bone metabolism by gender were consistent with BMD changes. A 1-year treatment with intramuscular clodronate determined a significant reduction of bone loss after THA. This was mainly attributed to its greater efficacy in the female population, which is at higher risk for bone loss. This observation suggests the need for the characterization of high-risk subjects as potential candidates for prevention strategies. [ABSTRACT FROM AUTHOR]

Recent experimental evidence has challenged the paradigm according to which radiation traversal through the nucleus of a cell is a prerequisite for producing genetic changes or biological responses. Thus, unexposed cells in the vicinity of directly irradiated cells or recipient cells of medium from irradiated cultures can also be affected. The aim of the present study was to evaluate, by means of the medium transfer technique, whether interleukin-8 and its receptor (CXCR1) may play a role in the bystander effect after gamma irradiation of T98G cells in vitro. In fact the cell specificity in inducing the bystander effect and in receiving the secreted signals that has been described suggests that not only the ability to release the cytokines but also the receptor profiles are likely to modulate the cell responses and the final outcome. The dose and time dependence of the cytokine release into the medium, quantified using an enzyme linked immunosorbent assay, showed that radiation causes alteration in the release of interleukin-8 from exposed cells in a dose-independent but time-dependent manner. The relative receptor expression was also affected in exposed and bystander cells. [ABSTRACT FROM PUBLISHER]

Telomeres are specialised nucleoprotein complexes that serve as protective caps of linear eukaryotic chromosomes. The loss of the ends of the chromosomes due to these un-rejoined double strand breaks (DSBs) may not be lethal to the cell, but may instead result in the loss of functional telomeres, chromosome fusions and initiation of breakage/fusion/bridge cycle-induced chromosome instability. The telomeres also participate in the process of DNA repair, as evidenced by ‘de novo’ synthesis of telomere repeats at DSBs and by the capacity of telomeres to binding the essential components of the DNA repair machinery. Based on the observation that high-LET radiations efficiently induce chromosome aberrations, it was tested whether protons were able to affect telomere structure. Human primary fibroblasts (HFFF2) and mouse embryonic fibroblasts (MEFs) were irradiated with 4 Gy of 3 MeV protons at the radiobiology facility of the INFN-LNL. Experiments with X rays were also carried out. Cells were fixed after either 24 h or 15 d from treatment. A difference in average telomere length, measured by quantitative fluorescence in situ hybridisation (Q-FISH), between X rays and protons treatment was observed. X rays are able to modify telomere length in HFFF2 harvested at a later time. On the other hand, 3 MeV low-energy protons induced, both in HFFF2 and in MEFs, a significant increase in telomere length at short as well as at long harvesting time periods from treatment. These results seem to indicate that lesions characterised by different complexity, as those expected after low-energy protons and those induced by damage similar to that induced by sparsely ionising radiation, are able to modulate telomere elongation at different time periods. [ABSTRACT FROM PUBLISHER]

Purpose: To quantify the role played by radiation track structure and background fragments in modulating DNA fragmentation in human cells exposed to ?-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 ?-rays and 0.84 MeV protons (Linear Energy Transfer, LET, in tissue 28.5 keV/µm). 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 ?-rays). Results: For both ?-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) • 10 -9 Gy -1 bp -1 for ?-rays and (7.1 ± 0.6) • 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 ?-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. [ABSTRACT FROM AUTHOR]

In this paper we present a magneto-optical analysis of local current densities in YBCO films, before and after 3.5 MeV proton irradiation. The main issue consists into measuring and interpreting the temperature dependence of the critical current density (Jc) in samples with different, increasing defect density. Proton irradiation adds more point defects into the as-grown films. The new defect density as well as the related strain-induced modifications of the order parameter are pushed in our experiment up to temperature-modulated damage thresholds. First of all model-independent Jc data were analysed in the framework of different pinning models, all of them based on mechanisms related to the temperature induced change of the effective pinning centre distribution as well as to the shape of single pinning wells. It turns out that in such a framework the fit parameters are, generally speaking, not suitable to interpret the changes of the pinning landscape across the whole investigated temperature range. Then a model based on a vortex distribution across the whole sample, resulting in a current density that mirrors the current through a defect-modulated average short Josephson junction (JJ) row, is successfully tried. The Jc dependence in the whole temperature range and for all the considered defect densities is accounted for by means of a coherent set of fit parameters. It turns out that the chief quantity that allows applying the JJ formalism to a vortex distribution across the defected matrix is a suitably defined temperature-dependent magnetic thickness of the junctions, which substitutes the usual magnetic penetration in JJs. [ABSTRACT FROM AUTHOR]

Synergism between anti-HER2 monoclonal antibody (trastuzumab) and paclitaxel has been shown in vitro and in vivo. In previous experiences, weekly administration of trastuzumab and paclitaxel has shown significant activity in metastatic breast cancer. In this phase II study, we evaluated the activity and the toxicity of this weekly regimen in anthracycline- and taxane-pretreated patients with HER2-overexpressing metastatic breast cancer. Between November 1999 and July 2001, 25 patients were treated with trastuzumab (4?mg?kg-1 i.v. loading dose followed by 2?mg?kg-1 i.v.?week-1) and paclitaxel (60-90?mg?m-2?h-1 i.v. infusion?week-1). The treatment was planned to continue until disease progression or prohibitive toxicity; in patients with responsive or stable disease, after 6 months of therapy, the decision to stop paclitaxel while continuing weekly trastuzumab was left to the physicians' judgement. At the median follow-up of 19.6 months (range 9.2-38.1), all patients are evaluable for response and toxicity. We obtained four (16%) complete responses (CR), 10 (40%) partial responses (PR), four (16%) stable diseases and seven (28%) disease progressions. The response rate (CR+PR) was 56% (95% CI, 36.5-75.5%). The median duration of response was 10.4 months (range 4.1-24.2+). Median time to progression was 8.6 months (range 2.5-24.2+). The toxicity was mild; five patients experienced fever and chills during the first infusion of trastuzumab (20%); leukopenia grade 2 was recorded in one patient (4%). Two patients (8%) came off study for grade 3 cardiotoxicity (after 9 and 17 weeks of treatment, respectively): both had already received anthracyclines and taxanes. Onycholysis grade 2 was observed in five patients (20%). These results confirm that weekly administration of trastuzumab and paclitaxel is active in anthracycline- and taxane-pretreated metastatic breast cancer patients HER2-overexpressing. Since cardiac disfunctions grade 3 were observed (8%), we recommend that cardiac function should be monitored in these patients.British Journal of Cancer (2004) 90, 36-40. doi:10.1038/sj.bjc.6601485 www.bjcancer.com [ABSTRACT FROM AUTHOR]

Purpose: To evaluate and compare cytotoxic and mutational effects of graded doses of γ-rays and [sup 4]He[sup ++] ions at different LET values (nominally 80 and 123 keV/μm) in V79 cells. Materials and methods: [sup 4]He[sup ++] ion beams at 80 and 123 keV/μm were supplied by the 7 MV Van de Graaff CN accelerator of the INFN-LNL in the dose range 0.3-2.4 Gy at a dose rate of 1 Gy/min. Gamma-irradiation was performed by the [sup 60]Co 'γ beam' of CNR-FRAE (at the INFN-LNL) in the dose range 0.5-6.0 Gy at a dose rate of 1 Gy/min. After irradiation, the cells were seeded to measure surviving fraction (SF) and mutant frequency (MF) at the Hprt locus on the basis of 6-thioguanine resistance. Alterations at minisatellite sequences (MS) of clones derived from irradiated and unirradiated cells were detected by Southern blot analysis using a multi-locus probe (DNA fingerprinting). Results: Survival data from [sup 4]He[sup ++] irradiation at two LET values (80 and 123 keV/μm) yielded similar results: α=(1.08±0.04)/Gy and (0.90±0.03)/Gy, respectively. The best fit for mutant induction at the Hprt locus after 80 keV/μm [sup 4]He[sup ++] was a linear function of the dose in the dose-interval 0-1.5 Gy: α=(47.77±16.01)×10[sup -6]/Gy. The best fit for mutant induction after 123 keV/μm [sup 4]He[sup ++] in the dose-interval 0-1.2 Gy was a linear-quadratic function: α=(86.01±13.80)×10[sup -6]/Gy; β=(42.87±11.03)×10[sup -6]/Gy[sup 2]. For γ-irradiation, the best fit of Hprt mutation data gave: α=(4.14±2.67)×10[sup -6]/Gy; β=(0.63±0.86)×10[sup -6]/Gy[sup 2]. The best fitting of MS alteration data with linear-quadratic or linear relationships gave: for γ-rays, α=0.56 mutants/Gy and β=0.52 mutants/Gy[sup 2]; for 80 keV/μm [sup 4]He[sup ++], α=3.70 mutants/Gy and β=9.00 mutants/Gy[sup 2]; for 123 keV/μm [sup 4]He[sup ++], α=4.36 mutants/Gy. Conclusions: The results reported here confirmed the higher cytotoxic and mutagenic effects of helium ions in comparison with γ-irradiation and the ability of DNA fingerprint analysis to investigate DNA damage induced by different ionizing radiations. The results of the mutagenic effects measured by the two tests are in agreement. [ABSTRACT FROM AUTHOR]

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 loop dimensions, of the double-strand breaks induced by γ-rays and by light ions. These effects may have a role in the observed different cell response to these radiations. [ABSTRACT FROM AUTHOR]

Purpose: To examine the low-dose sensitivity of V79 cells under exposure to γ-rays and [sup 4]He ions of different energies. Materials and methods: Cell survival and cytogenetic analysis using the Giemsa technique were studied following irradiation to doses of 0-3 Gy at the INFN-LNL facilities. Results: Low-dose hyper-radiosensitivity (HRS) of V79 was demonstrated after irradiation with γ-rays and α-particles of various linear energy transfers (LET) (58.9, 79.3 and 101.7 keV μm[sup -1]). Cytogenetic analysis showed an LET dependence of aberrations at a dose of 1Gy; the frequency of chromatid fragments appeared to vary with the number of α-particles traversing the cell nucleus. The results of both studies fit together to give a better understanding of so-called 'induced radioresistance' phenomenon. Conclusions: The mechanism of induced cellular radioresistance appears to be initiated after a certain amount of energy is deposited in the cell nucleus. This amount depends on both radiation quality and the number of particles traversing the cell. [ABSTRACT FROM AUTHOR]

We report the occurrence of chromosome instability in human T lymphocytes irradiated in vitro with γ-rays and cultured for several generations before analysis. The delayed effects of γ-radiation have been evaluated by conventional and molecular (chromosome painting) cytogenetics in preparations obtained from long-term bulk cultures or clonal cultures. The results indicate that the cell progeny of γ irradiated human T lymphocytes can be characterized by a higher rate of chromosome damage, but this effect depends on the individual donor response to ionizing radiation. Evidence has been collected about a differential involvement of chromosomes 7, 9 and 19 in the induced chromosome rearrangements, and this effect is equally visible as an immediate or delayed response of human T lymphocytes to ionizing radiation. [ABSTRACT FROM PUBLISHER]

Surface columnar defects, SCDs, are produced in high quality (Bi,Pb)[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub y]/Ag tapes by irradiating them with 0.25 GeV gold ions only on a top layer up to ≈15% of the full volume. The ion beam is orthogonal to the tape plane. In this paper we report experimental results of the surface implantation of columnar defects both in the high-current and in the lowcurrent regime with a particular emphasis on the influence of SCDs on the anisotropy dependent properties. Some characteristic labels of the SCD implantation are pointed out. A comparison between all the results in the two current regimes is made. A hint is given concerning analogous results obtained by means of transport electrical measurements. The experimental data can be interpreted by assuming that a new confined phase driven by SCDs sets up in both the current regimes. Acting on the dose, it is possible to obtain tunable control of the in-field performance in both regimes. [ABSTRACT FROM AUTHOR]

Purpose: To study the induction and the time-course of rejoining of DNA double strand breaks (DSB) in V79 cells irradiated with light ions with different linear energy transfer (LET). Materials and methods: V79 cells were irradiated in monolayer with monoenergetic proton, deuteron, helium-3 or helium-4 ion beams, each at two different energy values. Gamma rays were used as reference radiation. DSB have been measured by constant field gel electrophoresis (CFGE). Results: The initial yield depended little on the particle type and LET. The amount of DSB left unrejoined for up to 2 h incubation time could be roughly described by a decreasing exponential function with a final plateau, although more complex functions cannot be excluded. Radiation quality had little effect on the rejoining rate but affected the plateau. The amount of residual DSB after 2h was higher for densely than for sparsely ionizing radiation, and for the same particle was dependent on LET. The corresponding RBE ranged from 1.8 to 6.0. Conclusions: The results support the hypothesis that complex, less reparable DSB are induced in higher proportion by light ions with respect to gamma-rays and that, for the same ion, increasing LET leads to an increase in this proportion. [ABSTRACT FROM AUTHOR]

Purpose: To analyse the cell inactivation frequencies induced by low energy protons in human cells with different sensitivity to photon radiation. Materials and methods: Four human cell lines with various sensitivities to photon irradiation were used: the SCC25 and SQ20B derived from human epithelium tumours of the tongue and larynx, respectively, and the normal lines M/10, derived from human mammary epithelium, and HF19 derived from a lung fibroblast. The cells were irradiated with γ-rays and proton beams with linear energy transfer (LET) from 7 to 33keV/μm. Clonogenic survival was assessed. Results: Survival curves are reported for each cell line following irradiation with γ-rays and with various proton LETs. The surviving fraction after 2 Gy of γ-rays was 0.72 for SQ20B cells, and 0.28–0.35 for the other cell lines. The maximum LET proton effectiveness was generally greater than that of γ-rays. In particular there was a marked increase in beam effectiveness with increasing LET for the most resistant cells (SQ20B) whose 2 Gy-survival varied from 0.72 with γ-radiation down to 0.37 with 30keV/μm protons. The relative biological effectiveness (RBE(2Gy γ)) with the 30 keV/μm beam, evaluated as the ratio of 2Gy to the proton dose producing the same inactivation level as that given by 2 Gy of γ-rays, was 3.2, 1.8, 1.3 and 0.8 for SQ20B, M/10, SCC25, and HF19, respectively. Conclusions: RBE for inactivation with high-LET protons increased with the cellular radioresistance to γ-rays. The cell line with the greatest resistance to γ-rays was the most responsive to the highest LET proton beam. A similar trend has also been found in studies reported in the literature with He, C, N ions with LET in the range 20–125keV/μm on human tumour cell lines. [ABSTRACT FROM AUTHOR]

Purpose: To study the relative biological effectiveness-linear energy transfer (RBE-LET) relationship for micronuclei (MN) and cell inactivation, in Chinese hamster cells irradiated with low-energy protons (0.88 and 5.04 MeV, at the cell entrance surface). Chromosome loss was also investigated by means of antikinetochore CREST staining. Materials and methods: Cl-1 cells were exposed to different doses of X-rays, gamma-rays, 7.7 keV/mum and 27.6 keV/mum protons. The induction of MN, the distribution of MN per cell and the frequency of CREST-positive MN were evaluated in cytokinesis-blocked binucleated cells (BN cells) in the dose range 0.125-3 Gy. In parallel, cell survival experiments were carried out in samples irradiated with 0.5 to 4 Gy. Results: MN yield and the frequency of BN cells carrying multiple MN ( 2) were significantly higher after exposure to 27.6 keV/mum protons, compared with the other radiation types. In contrast, MN induction and MN distribution per BN cell were similar among 7.7 keV/mum protons, X- and gamma-rays up to 1 Gy. Cell survival experiments gave RBE values very close to those obtained with the MN assay. Both X-rays and 27.6keV/mum protons yielded a significant proportion of CREST-positive MN at the highest doses investigated (0.75-3Gy). Conclusions: Good correlations between MN induction and cell inactivation were observed for both low- and high-LET radiation, indicating that the MN assay can be a useful tool to predict cell sensitivity to densely ionizing radiation with implications for tumour therapy with protons. [ABSTRACT FROM AUTHOR]

Thirty-two children affected by juvenile rheumatoid arthritis (JRA) were studied with serial measurements of bone mass for an average of 18 months, to evaluate the effects of long-term methotrexate (MTX) treatment on bone. Bone mineral density (BMD) was measured on lumbar spine and total body. During MTX therapy some increase in BMD was observed, though this was smaller than in a control group of healthy children. Axial (spine and trunk) and appendicular (upper and lower limbs) BMD showed similar increases. BMD, either as an absolute value or as a percent variation from baseline, did not correlate with either MTX dose or length of therapy. In children treated also with corticosteroids, these drugs negatively influenced bone mass increase. The main determinant of absolute spine BMD value appeared to be weight, while height and lean mass seemed to be the determinants of total body BMD. Pubertal stage and disease activity significantly influenced the yearly change in BMD. In conclusion, our data suggest that long-term, low-dose therapy with MTX does not induce osteopenia in children with JRA. [ABSTRACT FROM AUTHOR]

Purpose: To determine the yield of mitotic catastrophe induced after low energy proton irradiation and to compare this yield with that induced by X-rays. Materials: Asynchronous Chinese hamster V79 cells were irradiated with 0.5, 1, 2, 5 and 10Gy proton beams and X-rays. Proton LET of 7.7, 11.0 and 30.5keV mu m1, corresponding to energies of 5.01, 3.20 and 0.76MeV respectively, evaluated at the cell mid-plane, were used for experiments. The occurrence and yield of mitotic catastrophe was measured as the percentage of cells exhibiting fragmented nuclei. Results: Proton irradiation led to an enhanced induction of mitotic catastrophe in V79 cells. The onset of nuclear fragmentation, a hallmark of mitotic catastrophe, occurred much earlier after cell exposure to proton particles than to X-ray irradiation. Conclusions: Mitotic catastrophe is persistent in the subsequent cell generations after proton and X irradiation of V79 cells; but protons are more effective than X-rays for the induction of this phenomenon. These results are discussed in terms of their importance in space exposures and possible acquisition of genomic instability by the progeny of irradiated cells. [ABSTRACT FROM AUTHOR]

The possibility to enhance in a predictable way the superconducting properties behavior of a bulk material by introducing linearly correlated defects within a surface layer has been demonstrated. Ag/BSCCO-2223 tapes were irradiated by means of 0.25 GeV Au ions at different fluences, with a dose equivalent field Bθ ranging from 1 T to 5 T. The implantation depth was about 15 µm corresponding to about 15% of the total sample thickness. Sample independent enhancements of different a.c and d.c properties show up, due to vortex confinement in the whole sample. The sample independence exhibited by all the experimental findings as well as, on the other side, the dose dependence of the enhancements, allow to design in advance the performances of a monofilamentary tape where defect trenches of nanometric size are scratched. [ABSTRACT FROM AUTHOR]

We irradiated both side of bulk melt textured YBCO with 235 MeV Au ions. The thickness of the specimens is significantly larger than the penetration range of the ions so that two surface layers of columnar defects are created. Critical current density enhancements were obtained in temperature and field ranges that are useful for applications. The boundary between reversible and irreversible regime is shifted toward higher temperatures. At higher fields the increase of the relaxation rate with temperature is less steep after irradiation. The general trends are independent of the thickness of the samples, at least in the range from 5% to 13% of volume affected by irradiation. [ABSTRACT FROM PUBLISHER]

We have experimentally investigated the effects of intense proton beam irradiation (up to 10/sup 15/ p/cm/sup 2/) on Josephson junctions and junction arrays. The devices we have studied were realized using state of the art full-Nb technology, employing same materials and thicknesses of common Josephson digital circuit designs. We have analysed in detail the magnetic field dependence of the junction critical current, and the quasiparticle tunneling current, in order to observe possible occurrence of permanent changes produced by the ionizing particles. No evidence of radiation induced damage on the properties of the junctions has been found. [ABSTRACT FROM PUBLISHER]

Dual X-ray absorptiometry (DXA) instruments are now able to evaluate bone mineral density (BMD) of bone surrounding metal implants. The assessment of BMD around prosthetic components could provide additional information for the follow-up of total hip arthroplasty (THA). In this study, we evaluated the potential application of DXA in the field of THA. BMD was measured in the proximal femur of both THA and THA-free sides in 14 postmenopausal women 6-18 months after THA. The explored segment was divided into seven zones as proposed by Gruen et al. [18]. The precision error of BMD measurements ranged from 1.8 to 6.8% on the THA side and from 1.1 to 2% to the THA-free side. The reduction of BMD of the THA versus the THA-free side was significant in all seven zones (P < 0.01, t-test for paired data). These results showed significant differences in BMD around femoral components of THA with respect to contralateral healthy side, and demonstrate the sensitivity of DXA for detecting these changes. [ABSTRACT FROM AUTHOR]

Purpose: RBE-LET relationships for cell inactivation and hprt mutation in V79 cells have been studied with mono-energetic low-energy proton beams at the radiobiological facility of the INFN-Laboratori Nazionali di Legnaro (LNL), Padova, Italy. Materials and methods : V79 cells were irradiated in mono-layer on mylar coated stainless steel petri dishes, in air. Inactivation data were obtained at 7.7, 34.6 and 37.8 keV/ mu m and hprt mutation was studied at 7.7 and 37.8 keV/ mu m. Additional data were also collected for both the end points with the proton LET already considered in our previous publications, namely 11.0, 20.0 and 30.5keV/ mu m. Results : A maximum in the RBE-LET relationship for cell inactivation was found at around 31keV/ mu m, while the RBE for mutation induction increased continuously with LET. Conclusions : The proton RBE-LET relationship for cell inactivation is shifted to lower LET values compared with that for heavier ions. For mutation induction, protons of LET equal to 7.7 keV/ mu m gave an RBE value comparable with that obtained by helium ions of about 20 keV/ mu m. Mutagenicity and lethality caused by protons at low doses in the LET range 7.7-31keV/ mu m were proportional, while the data at 37.8keV/ mu m suggest that this may not hold at higher LET values. [ABSTRACT FROM AUTHOR]

Purpose: To determine the RBE-LET relationship for C3H10T1/2 cell inactivation by protons in the LET range 11-33 keV/ mu m and to compare inactivation frequencies induced in C3H10T1/2 cells by protons and deuterons at two matching LET values in the range 11-20 keV/ mu m. Materials and methods: C3H10T1/2 cells were irradiated with protons and deuterons at the radiobiological facility set up at the 7 MV Van de Graaff accelerator at the LNL, Legnaro, Padova. Gamma rays from 60Co were used as reference radiation. Results: Proton RBE values ( alpha / alpha c ) for inactivation of C3H10T1/2 cells are constant around a value of 2 between 11 and 20 keV/ mu m and then rise sharply to reach a value of 4.2 1.0 at 33 keV/ mu m. Deuteron RBE values are 1.7 0.4 and 2.2 0.6 at LET values of 13 and 18 keV/ mu m respectively. Conclusions: Proton RBE values with C3H10T1/2 cells are significantly larger than unity at LET values as low as 11 keV/ mu m. No difference in effectiveness for inactivation of C3H10T1/2 has been found between protons and deuterons at two LET values in the range 10-20 keV/ mu m. [ABSTRACT FROM AUTHOR]

PIGE and PIXE techniques were employed to the study of elemental constituents of some traditional medicinal plants generally used in curing many diseases and ailments in southwestern Nigeria. Analyses were also carried out on commonly edible vegetables of medicinal and pharmacological importance. PIGE measurements were carried out using 3.5-MeV collimated protons from the 7 mV CN Van-de-Graaff accelerator of INFN, LNL, Legnaro (Padova), Italy, whereas the PIXE measurements were carried out using 1.8 MeV from the 2.5 MV AN 2000 Van-de-Graaff accelerator of the same laboratory. The results show that many of the medicinal plants contain elements of cardinal importance in human metabolism. The results from the vegetables also show the presence of vital elements that are needed for growth and development. In addition, some of the toxic elements, which include As, Cd, Hg, and so forth, were not detected. However, some of the recipes contain trace amounts of Pb at very low concentrations. This calls for proper control of dose rates in some samples to prevent the attendant negative cumulative effects. [ABSTRACT FROM AUTHOR]

The results of a measurement of the neutron emission from a Ti (metal)/D (gas) system by means of a spectrometer based on double scattering are reported. A∼2.5 σ signal corresponding to an emission of (1.3±0.5) neutron s g has been observed. [ABSTRACT FROM AUTHOR]

The characteristics and tests of a fast neutron production and scattering chamber assembly is presented here, based on theLi(p, n)Be reaction(s). This assembly, which consists of a small vacuum scattering chamber designed to house home-made LiF targets and a SSB detector to monitor the target thickness (yield), has been tested at various proton energies, starting from 1.95 MeV, on the 7 MV CN Van de Graaff accelerator of the INFN-Laboratori Nazionali di Legnaro (Padova), Italy. [ABSTRACT FROM AUTHOR]