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L'obiettivo di questa revisione è identificare metodi efficaci per migliorare l'impegno e l'adesione delle famiglie ai programmi di parent training (BPT). Nonostante la letteratura indichi risultati positivi, spesso le famiglie mostrano uno scarso impegno, fino a giungere a un precoce abbandono del percorso terapeutico. Ciò comporta una serie di conseguenze negative per le famiglie, i clinici, la ricerca e il servizio sanitario nazionale. La letteratura, ad oggi, individua alcuni fattori predittivi del drop-out e varie componenti da includere nei parent training per aumentare l'impegno e l'adesione alle procedure di intervento. Tra strategie di coinvolgimento, alcuni autori suggeriscono l'utilizzo di un promemoria degli appuntamenti, brevi discussioni iniziali sulla necessità di impegnarsi, metodi di coinvolgimento dei sistemi familiari, adattamenti strutturali del programma, incentivi finanziari, aumento del supporto familiare e colloqui motivazionali. Nonostante i programmi BPT abbiano un'elevata efficacia nel cambiamento del comportamento genitoriale, la letteratura evidenzia elevati livelli di drop-out, ragion per cui gli studi presentati hanno piccoli campioni che limitano il potere statistico e la generalizzabilità dei risultati.

This study aimed to further validate the self-reported version of the Proposed Specifiers Conduct Disorder (PSCD) scale, testing the associations between the PSCD with a scale that measures emotional/behavioral difficulties and prosocial behaviors (Strength and Difficulties Questionnaire, SDQ). A total of 536 Italian students (47.76% male, 11–14 years) completed the PSCD, while their caregivers and teachers completed the SDQ. A series of confirmatory factor analyses to test the best fitting model were run. The internal consistency of the PSCD was evaluated, and the correlations between the PSCD self-reported scores and SDQ Parent and Teacher report scores were examined. A bi-factor model was fitted with a refined 19-item version of the scale, which showed adequate fit indices. The PSCD total score was strongly associated with higher parent- and teacher-rated conduct problems, hyperactivity, and lower prosocial behavioral symptoms. In conclusion, this study indicated that the self-report PSCD shows preliminary promise as a reliable, easy-to-use tool, for measuring psychopathic traits in Italian children and young adolescents.

Although obsessive–compulsive disorder (OCD) and the conduct disorders (CD) express a contrasting symptomatology, they could represent different answers to a common matrix about morality. In the literature, some theoretical models describe people with OCD as individuals who experience high levels of responsibility and guilt. On the other hand, adolescents with a CD are described as if they do not feel guilty at all or consider anti-social purposes as more important than existing moral purposes. The aims of this study were to investigate the role of forgiveness in responsibility and guilt levels and to test whether this putative relation was influenced by tendencies towards obsessive–compulsive problems (OCP) or conduct problems (CP). In total, 231 adolescents aged between 16 and 18 years were self-assessed using a Youth Self-Report, Child Responsibility Attitudes Questionnaire, Heartland Forgiveness Scale, and Test Of Self-Conscious Affect. The results show that self-forgiveness predicted responsibility levels, while guilt was predicted by self-forgiveness and situation-forgiveness. Moreover, mediation analyses revealed that the effects of OCP on responsibility and guilt were mediated by self-forgiveness and situation-forgiveness. Regarding CP, no mediated effects were found. In conclusion, lower proneness to forgive increases responsibility and guilt, and this is particularly evident in subjects with higher levels of OCP.

Space radiation represents one of the major health hazards to crews of interplanetary missions. As the duration of space flight increases, according to International Space Station (ISS) and Mars mission programs, the risk associated with exposure to ionizing radiation also increases. Although physical dosimetry is routinely performed in manned space missions, it is generally accepted that direct measurement of biological endpoints (biological dosimetry) is necessary for a precise assessment of radiation risk in extraterrestrial activities. Chromosomal aberrations (CAs) in peripheral blood lymphocytes (PBLs) are particularly suitable to this purpose, as they can provide estimates of both equivalent radiation dose and risk. In this study, cytogenetic analysis was performed on PBL chromosomes of an Italian astronaut involved in two different 10-day missions on the ISS (Marco Polo, April 2002, and ENEIDE, May 2005). Blood samples were collected before and after flights. CAs were evaluated in either mitotic spreads or in prematurely condensed chromosomes (PCC) by Fluorescence in Situ Hybridization (FISH). In addition, blood samples were exposed to graded doses of X-rays in vitro before and after the flight and cytogenetic damage evaluated to investigate whether the space environment alters the sensitivity of human cells to ionizing radiation. The yield of baseline chromosomal aberrations was not modified following Marco Polo and ENEIDE mission. This is consistent with the low dose absorbed in these short-term space missions. Preliminary results from Marco Polo mission suggested a significant increase in intrinsic radiosensitivity of lymphocytes after landing compared to pre-flight and follow-up (6 months after landing) samples. However, this effect was not observed during the ENEIDE mission. The results suggest that intra-indi-vidual variations in radiosensitivity are significant, but they cannot be related to the space flight.

We report results for chromosomal aberrations in human peripheral blood lymphocytes after they were exposed to high-energy iron ions with or without shielding at the HIMAC, AGS and NSRL accelerators. Isolated lymphocytes were exposed to iron ions with energies between 200 and 5000 MeV/nucleon in the 0.1-1-Gy dose range. Shielding materials consisted of polyethylene, lucite (PMMA), carbon, aluminum and lead, with mass thickness ranging from 2 to 30 g/cm(2). After exposure, lymphocytes were stimulated to grow in vitro, and chromosomes were prematurely condensed using a phosphatase inhibitor (calyculin A). Aberrations were scored using FISH painting. The yield of total interchromosomal exchanges (including dicentrics, translocations and complex rearrangements) increased linearly with dose or fluence in the range studied. Shielding decreased the effectiveness per unit dose of iron ions. The highest RBE value was measured with the 1 GeV/nucleon iron-ion beam at NSRL. However, the RBE for the induction of aberrations apparently is not well correlated with the mean LET. When shielding thickness was increased, the frequency of aberrations per particle incident on the shield increased for the 500 MeV/nucleon ions and decreased for the 1 GeV/nucleon ions. Maximum variation at equal mass thickness was obtained with light materials (polyethylene, carbon or PMMA). Variations in the yield of chromosomal aberrations per iron particle incident on the shield follow variations in the dose per incident particle behind the shield but can be modified by the different RBE of the mixed radiation field produced by nuclear fragmentation. The results suggest that shielding design models should be benchmarked using both physics and biological data.

The aim was to evaluate the effect of modelled microgravity on radiation-induced chromosome aberrations (CAs). G(0) peripheral blood lymphocytes were exposed to 60 MeV protons or 250 kV(p) X-rays in the dose range 0 - 6 Gy, and allowed to repair DNA damage for 24 h under either normal gravity or microgravity modelled by the NASA-designed rotating-wall bioreactor. Cells were then stimulated to proliferate by phytohaemagglutinin (PHA) under normal gravity conditions and prematurely condensed chromosomes were harvested after 48 h. CAs were scored in chromosomes 1 and 2 by fluorescence in-situ hybridization. Proliferation gravisensitivity was examined by cell growth curves and by morphological evaluation of mitogen-induced activation. Cell replication rounds were monitored by bromodeoxyuridine labelling. Modelled microgravity markedly reduced PHA-mediated lymphocyte blastogenesis and cell growth. However, no significant differences between normal gravity and modelled microgravity were found in the dose - response curves for the induction of aberrant cells or total interchromosomal exchange frequency. Rotating-wall bioreactor-based microgravity reproduced space-related alterations of mitogen stimulation in human lymphocytes but did not affect the yield of CAs induced by low-linear energy transfer radiation.

Biophysical models are commonly used to evaluate the effectiveness of shielding in reducing the biological damage caused by cosmic radiation in space flights. To improve and validate these codes biophysical experiments are needed. We have measured the induction of chromosomal aberrations in human peripheral blood lymphocytes exposed in vitro to 500 MeV/ n iron ion beams (dose range 0.1–1 Gy) after traversing shields of different material (lucite, aluminium, or lead) and thickness (0–11.3 g/cm 2 ). For comparison, cells were exposed to 200 MeV/ n iron ions and to X-rays. Chromosomes were prematurely condensed by a phosphatase inhibitor (calyculin A) to avoid cell-cycle selection produced by the exposure to high-LET heavy-ion beams. Aberrations were scored in chromosomes 1, 2, and 4 following fluorescence in situ hybridization. The fraction of aberrant lymphocytes has been evaluated as a function of the dose at the sample position, and of the fluence of primary 56 Fe ions hitting the shield. The influence of shield thickness on the action cross-section for the induction of exchange-type aberrations has been analyzed, and the dose average-LET measured as a function of the shield thickness. These preliminary results prove that the effectiveness of heavy ions is modified by shielding, and the biological damage is dependent upon shield thickness and material.

The aim of this preliminary investigation was to assess whether human peripheral blood lymphocytes which have been pre-exposed to non-ionizing radiofrequency fields exhibit an adaptive response (AR) by resisting the induction of genetic damage from subsequent exposure to ionizing radiation. Peripheral blood lymphocytes from four healthy donors were stimulated with phytohemagglutinin for 24 h and then exposed for 20 h to 1950 MHz radiofrequency fields (RF, adaptive dose, AD) at an average specific absorption rate of 0.3 W/kg. At 48 h, the cells were subjected to a challenge dose (CD) of 1.0 or 1.5 Gy X-irradiation (XR, challenge dose, CD). After a 72 h total culture period, cells were collected to examine the incidence of micronuclei (MN). There was a significant decrease in the number of MN in lymphocytes exposed to RF + XR (AD + CD) as compared with those subjected to XR alone (CD). These observations thus suggested a RF-induced AR and induction of resistance to subsequent damage from XR. There was variability between the donors in RF-induced AR. The data reported in our earlier investigations also indicated a similar induction of AR in human blood lymphocytes that had been pre-exposed to RF (AD) and subsequently treated with a chemical mutagen, mitomycin C (CD). Since XR and mitomycin-C induce different kinds of lesions in cellular DNA, further studies are required to understand the mechanism(s) involved in the RF-induced adaptive response.

To measure clonogenic death of Chinese hamster V79 cells following exposure to a defined number of 4.3 MeV alpha-particles (track-averaged LET = 105 keV/micron).Cells were irradiated at the radiobiological facility installed at the TTT-3 Tandem accelerator in Naples by using a 'Biostack' approach, which allows the positions of incident tracks relative to cells to be carefully determined. Subcellular structure was identified by fluorescence microscopy, while tracks were visualized by LR-115 solid state nuclear track detectors.Particle hits in the cytoplasm did not significantly affect cell survival, yet survival probability decreased exponentially as a function of the number of nuclear traversals. Measured probability of surviving to exactly one 4.3 MeV alpha-particle traversal in the cell nucleus was 0.67 +/- 0.10. Inactivation cross-section was substantially higher than expected from conventional survival curves. However, folding of the data with Poisson statistics showed that survival level expected if a mean of one alpha-particle goes through a nucleus is higher than the measured value after exactly one particle traversal.V79 cells have about 67% probability to survive a single alpha-particle traversal in the cell nucleus. Single-particle survival curves are consistent with conventional dose-survival relationships, once Poisson distribution of traversals is taken into account.

The use of charged particles significantly reduces the dose absorbed by normal cells due to the inverse dose-depth deposition profile. This is the physical pillar justifying hadrontherapy as the eligible treatment for deepseated tumours. However, a non-negligible amount of radiation is nevertheless absorbed in correspondence with the plateau region of the Bragg curve, which may result in the induction of sub-lethal effects. Very little experimental data exist on the induction of such effects. Moreover, reliable follow-up data on such adverse effects in hadrontherapy patients are limited since this type of treatment has been adopted relatively recently. A fortiori, the dependence of sub-lethal effects on unprecedented factors, such as the exceedingly high dose rates and/or the pulsed nature of beams originated by laser interaction with target materials, is unknown. This warrants investigation prior to a therapeutic use of such beams.

Inactivation of mouse C3H 10t½ cells in plateau-phase (7·8 × 104 cells/cm2) was studied by using α-particles from the irradiation facility installed for radiobiological experiments at the 3 MV Tandem accelerator, University of Naples. Silicon detectors and CR39 plastic track detectors were employed for dosimetric purposes. The cells were exposed to high LET monoenergetic α-particles (energy of 1·8 MeV at the centre of the cell nucleus, track-averaged LET of 177 keV/µm and dose-rate of 1·1 Gy/min) and low-LET 80 kVp X-rays. The X-ray survival curve showed a significant shoulder (α/β = 9 Gy) while the survival curve for α-particles was close to exponential. The mean lethal dose of α-particles was 0·77 ± 0·02 Gy and the RBE was 5·2 at 80% survival and 3·0 at 5% survival. Survival of exponentially growing cells (2 × 104 cells/cm2) following irradiation with the α-particle beam is also reported. The nuclear areas of 10T½ cells were measured as 299 ± 9 µm2 and 250 ± 8 µm2 for cells in log phase and plateau phas...

Midterm Syrian Hamster embryo (SHE) cells were employed to study high LET-radiation induced tumorigenesis. Normal SHE cells (secondary passage) were irradiated with accelerated helium ions at an incident energy of 22 MeV/u (9-10 keV/micrometer). Transformed clones were isolated after growth in soft agar of cells obtained from the foci of the initial monolayer plated postirradiation. To study the progression process of malignant transformation, the transformed clones were followed by monolayer subculturing for prolonged periods of time. Subsequently, neoplasia tests in nude mice were done. In this work, however, we have focused on karyotypic changes in the banding patterns of the chromosomes during the early part of the progressive process of cell transformation for helium ion-induced transformed cells.

We measured residual cytogenetic damage in the progeny of human peripheral blood lymphocytes exposed to 1 GeV/ nucleon iron ions or gamma rays. Arm-specific DNA probes for chromosome 1 were used to detect aberrations as a function of dose in cells harvested 144 h after exposure. In addition, arm-specific mFISH was applied to samples exposed to a single dose of 2 Gy. These methods allowed the detection of interarm intrachanges (pericentric inversions) in addition to interchanges. The ratio of these types of aberrations (F ratio) has been proposed as a fingerprint of exposure to densely ionizing radiation. The fractions of aberrant cells in the progeny of cells exposed to iron ions were similar to those in the population exposed to gamma rays, possibly because many rearrangements induced by heavy ions ultimately lead to cell death. Simple inter- and intrachanges were also similar, but more complex rearrangements were found in cells that survived after exposure to iron ions. We did not find a significant difference in the ratio of simple interchanges to simple intrachanges for the two radiation types. However, iron ions induced a much higher frequency of events involving both inter- and intrachanges. We conclude that these complex rearrangements represent a hallmark of exposure to heavy ions and may be responsible of the decrease of the F ratio with increasing LET reported in the literature in some in vitro and in vivo experiments.

Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel. It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation. Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris. We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum. As proxy to galactic nuclei we used 1 GeV n iron or titanium ions. Both physics and biology tests were performed. The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material. Physics tests show that its effectiveness is close (80-90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA. Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene. Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose.

The case for a DNA-damaging action produced by radio-frequency (RF) signals remains controversial despite extensive research. With the advent of the Universal Mobile Telecommunication System (UNITS) the number of RF-radiation-exposed individuals is likely to escalate. Since the epigenetic effects of RF radiation are poorly understood and since the potential modifications of repair efficiency after exposure to known cytotoxic agents such as ionizing radiation have been investigated infrequently thus far, we studied the influence of UNITS exposure on the yield of chromosome aberrations induced by X rays. Human peripheral blood lymphocytes were exposed in vitro to a UNITS signal (frequency carrier of 1.95 GHz) for 24 h at 0.5 and 2.0 W/kg specific absorption rate (SAR) using a previously characterized waveguide system. The frequency of chromosome aberrations was measured on metaphase spreads from cells given 4 Gy of X rays immediately before RF radiation or sham exposures by fluorescence in situ hybridization. Unirradiated controls were RF-radiation- or sham-exposed. No significant variations due to the UNITS exposure were found in the fraction of aberrant cells. However, the frequency of exchanges per cell was affected by the SAR, showing a small but statistically significant increase of 0.11 exchange per cell compared to 0 W/kg SAR. We conclude that, although the 1.95 GHz signal (UNITS modulated) does not exacerbate the yield of aberrant cells caused by ionizing radiation, the overall burden of X-ray-induced chromosomal damage per cell in first-mitosis lymphocytes may be enhanced at 2.0 W/kg SAR. Hence the SAR may either influence the repair of X-ray-induced DNA breaks or alter the cell death pathways of the damage response.

The objective of this study was to measure differences in the chromosomal rearrangements found in the progeny of cells exposed to the same dose of X-rays or energetic iron ions, with emphasis on intra-chromosomal exchanges. We hybridized metaphase cells with human DNA probes specific for the p and q arms of the chromosome 1. The arm-specific probes allow a fast and reliable detection of both symmetrical and asymmetrical inter-chromosomal exchanges and inter-arm intra-changes (pericentric inversions) in the painted chromosome pair. We used this method to score aberrations in human peripheral blood lymphocytes exposed to 1 Gy of either 250 kVp X-rays or 1 GeV/n Fe-ions and harvested following 120 h in culture, including 2 h in colcemid for metaphase-block. Although iron ions are much more effective than X-rays in the induction of chromosomal aberrations formed during the first post-exposure cell cycle, we found that the effectiveness drops when daughter cells are scored at a late harvest time. In fact, no significant difference in the yield of simple interchanges or intra-changes was found for the two radiation qualities. On the other hand, complex-type exchanges, including rearrangements involving both intra- and inter-chromosomal exchanges, were much more frequent in the progeny of the population exposed to Fe-nuclei than to photons.

Inheritable chromosome aberrations (CA) are of concern because cytogenetic damage may trigger the carcinogenic process. Moreover, stability of radiation-induced CA is a prerequisite for meaningful biological dosimetry. CA inheritability arguably depends on the aberration structure, with symmetrical exchanges being favoured over asymmetrical rearrangements, but it is also affected by radiation quality. CA induced by low-LET protons and high-LET 12C ions in G0 peripheral blood lymphocytes were measured in first- , second- and third-generation by combined FISH/harlequin staining of metaphase as well as prematurely condensed interphase chromosomes 1 and 2. As expected, the frequency of non-transmissible (NT) aberrations declined through replication rounds. A radiation-induced arrest occurred prior to first post-irradiation mitosis that prevalently affected aberrant cells. Aberrant cells incurred cycle delays also at subsequent cycles following proton-irradiation but not 12C ion-irradiation. As expected, the frequency of reciprocal translocations remained fairly stable while that of dicentrics was halved at each mitotic round. A significant fraction of complex-type exchanges was found in third-generation cells following both irradiations and appeared to be transmitted relatively more efficiently after protons than 12C ions. A low but stably transmitted frequency of transmissible (T)-type insertions were detected after 12C ions but not after low LET-irradiation. Our data support a differential ability by aberrant cells to progress through post-irradiation mitoses that is influenced by the aberration burden and radiation quality.

The induction of Robertsonian translocations in murine C3H 10T 1 2 embryo fibroblasts after exposure to X-rays and mitomycin C has been investigated. Cells were irradiated in log-phase and harvested at different times for chromosome analysis. The stage of the cell cycle of individual cells at the time of individual cells at the time of irradiation could be determined by differential replication staining. A dose-dependent delay in the progression through S- and G2-phase has been observed. X-rays produced an increase in the freqency of Robertsonian translocations when cells were exposed in G1- or S-phase, but not in G2. The dose-response curve for the induction of Robertsonian translocations both in G1 and S peaked at 2 Gy and slightly declined at higher doses. For G2 cells, an increase compared to the control level was observed only after 1 Gy. Mitomycin C induced chromosomal aberrations and Robertsonian translocations in 10T 1 2 cells, but no significant interaction between ionizing radiation and the alkylating agent was observed for these two endpoints. However, the combined exposure caused satellite associations of chromosomes. Both the number of satellite associations/metaphase (five times the frequency observed after mitomycin C alone) and the number of chromosomes/satellite (up to 10 chromosomes were observed in satellite associations) were greatly enhanced compared to X-rays and mitomycin C alone.

Large uncertainties are associated with estimates of equivalent dose and cancer risk for crews of longterm space missions. Biological dosimetry in astronauts is emerging as a useful technique to compare predictions based on quality factors and risk coefficients with actual measurements of biological damage in-flight. In the present study, chromosomal aberrations were analyzed in one Italian and eight Russian cosmonauts following missions of different duration on the MIR and the international space station (ISS). We used the technique of fluorescence in situ hybridization (FISH) to visualize translocations in chromosomes 1 and 2. In some cases, an increase in chromosome damage was observed after flight, but no correlation could be found between chromosome damage and flight history, in terms of number of flights at the time of sampling, duration in space and extra-vehicular activity. Blood samples from one of the cosmonauts were exposed in vitro to 6 MeV X-rays both before and after the flight. An enhancement in radiosensitivity induced by the spaceflight was observed.

Astronauts' radiation exposure limits are based on experimental and epidemiological data obtained on Earth. It is assumed that radiation sensitivity remains the same in the extraterrestrial space. However, human radiosensitivity is dependent upon the response of the hematopoietic tissue to the radiation insult. It is well known that the immune system is affected by microgravity. We have developed a mathematical model of radiation-induced myelopoiesis which includes the effect of microgravity on bone marrow kinetics. It is assumed that cellular radiosensitivity is not modified by the space environment, but repopulation rates of stem and stromal cells are reduced as a function of time in weightlessness. A realistic model of the space radiation environment, including the HZE component, is used to simulate the radiation damage. A dedicated computer code was written and applied to solar particle events and to the mission to Mars. The results suggest that altered myelopoiesis and lymphopoiesis in microgravity might increase human radiosensitivity in space.

In vitro radiobiological studies with ions require an extracted beam in air, uniformly spread over an area of at least 1 cm2 characterised by a good monochromaticity. Moreover an accurate fluence monitoring is needed together to an accurate off line calibration, taking into account the measurement geometry, to determine the absorbed dose. Finally energy, and then LET, following every traversed material, should be determined. In this framework we set up a facility at the 3 MV Tandem HVC TTT-3 accelerator of the University of Naples “Federico II” using light ions up to Z=6 and energy below 0.6 MeV n−1. Survival measurements of the V79 cell line following irradiation with beryllium, boron and carbon showed a good agreement with data from literature.

To analyse the cell inactivation frequencies induced by low energy protons in human cells with different sensitivity to photon radiation.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 y-rays and proton beams with linear energy transfer (LET) from 7 to 33 keV/microm. Clonogenic survival was assessed.Survival curves are reported for each cell line following irradiation with gamma-rays and with various proton LETs. The surviving fraction after 2 Gy of gamma-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 gamma-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 gamma-radiation down to 0.37 with 30 keV/microm protons. The relative biological effectiveness (RBE(2 Gy gamma)) with the 30 keV/microm beam, evaluated as the ratio of 2 Gy to the proton dose producing the same inactivation level as that given by 2 Gy of gamma-rays, was 3.2, 1.8, 1.3 and 0.8 for SQ20B, M/10, SCC25, and HF19, respectively.RBE for inactivation with high-LET protons increased with the cellular radioresistance to gamma-rays. The cell line with the greatest resistance to gamma-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 20-125 keV/microm on human tumour cell lines.

To investigate the mechanisms underlying the induction of chromosome aberrations by ionizing radiation, focusing attention on DNA damage severity, interphase chromosome geometry and the distribution of DNA strand breaks.An ab initio biophysical model of aberration induction in human lymphocytes specific for light ions was developed, based on the assumption that 'complex lesions' (clustered DNA breaks) produce aberrations, whereas less severe breaks are repaired. It was assumed that interphase chromosomes are spatially localized and that chromosome break free-ends rejoin pairwise randomly; the unrejoining of a certain fraction of free-ends was assumed to be possible, and small fragments were neglected in order to reproduce experimental conditions. The yield of different aberrations was calculated and compared with some data obtained using Giemsa or FISH techniques.Dose-response curves for dicentrics and centric rings (Giemsa) and for reciprocal, complex and incomplete exchanges (FISH) were simulated; the ratio between complex and reciprocal exchanges was also calculated as a function of particle type and LET. The results showed agreement with data from lymphocyte irradiation with light ions.The results suggest that clustered DNA breaks are a critical damage type for aberration induction and that interphase chromosome localization plays an important role. Moreover, the effect of a given particle type is related both to the number of induced complex lesions and to their spatial distribution.

The search for effective radioprotectors is of major concern in the medical, military, environmental, and space sciences. Conventional radioprotectors are generally effective only during a single irradiation and display their radioprotective properties only at high, toxic concentrations. In addition, they reduce somatic radiation effects but are poorly efficient in protecting from hereditary stochastic radiation effects. In this respect, the pigment melanin merits attention. Experiments referring to potential melanin effects on the ionising radiation response have been carried out with different biological systems, both in vivo and in vitro. In this paper, we present results on the response to high- and low-linear energy transfer (LET) radiation of a human mammary epithelial cell line, H184B5 F5-1 M/10, supplemented by melanin. The incorporation of auto-oxidative (L-dopa) melanin was linear for concentrations from 3 to 10 micrograms/ml in the growth medium. Concentrations of up to 250 micrograms/ml did not significantly impair the cells proliferative ability. No significant protective effect of melanin on the survival of cultured cells after exposure to alpha-particles (130 keV/micron) or x-rays was observed.

PURPOSE: To measure chromosome aberrations in C3H 10T1/2 mouse fibroblasts using FISH painting at the first mitosis following exposure to 30 keV/microm hydrogen or neon ions. MATERIALS AND METHODS: Cells in plateau-phase were irradiated with 0.86 MeV protons at the TTT-3 Tandem accelerator in Naples (Italy), or with 400 MeV/n Ne ions at the HIMAC accelerator in Chiba (Japan). Colcemid-blocked cells were harvested at the first mitosis following exposure, and chromosome spreads were hybridized in situ with a fluorescein-labelled composite mouse DNA probe specific for chromosomes 2 and 8. RESULTS: Protons were more efficient than neon ions at the same LET in the induction of chromosome interchanges and breaks. Yields of complex exchanges were similar for both particles at the same dose, but protons produced mostly insertions, while with Ne exposure non-reciprocal exchanges were the most frequent complex-type exchange. CONCLUSIONS: Charged particles with the same LET produce different yields of chromosome aberrations, and some observed differences can be explained based on the available track-structure models.

Uses of track-etch detectors in cellular radiation biology are reviewed. These applications are described in three main areas. First, with regard to dosimetry, nuclear track detectors should be used to measure beam uniformity, divergence, and fluence. Second, living cells attach and grow on many different kinds of track detectors. This property can be used to measure cell size by using nuclear methods. Cell thickness can be determined by measuring the energy of charged particles impinging a cell monolayer, and behind it. Also, nuclear images have been obtained as replicas on mica; the replicas can then be visualized with scanning electron microscopy. Finally, solid state track detectors play an important role in studies concerning the effectiveness of single-ion traversals in the cell nucleus or cytoplasm. Plastic detectors have been used for this purpose in many space missions in order to assess the risk from space radiation exposure to the crews. Similar techniques have been used in accelerator ground-based experiments. Tracks and living cells can be visualized either simultaneously or at different times. For the latter case, images of the irradiated cells, surviving colonies, and etched detector, being taken at different times, must be superimposed. Solid state nuclear track detectors can also be used in combination with microbeams for these kinds of studies.

Karyotypes of human cells surviving X- and alpha-irradiation have been studied. Human mammary epithelial cells of the immortal, non-tumorigenic cell line H184B5 F5-1 M/10 were irradiated and surviving clones isolated and expanded in culture. Cytogenetic analysis was performed using dedicated software with an image analyzer. We have found that both high- and low-LET radiation induced chromosomal instability in long-term cultures, but with different characteristics. Complex chromosomal rearrangements were observed after X-rays, while chromosome loss predominated after alpha-particles. Deletions were observed in both cases. In clones derived from cells exposed to alpha-particles, some cells showed extensive chromosome breaking and double minutes. Genomic instability was correlated to delayed reproductive death and neoplastic transformation. These results indicate that chromosomal instability is a radiation-quality-dependent effect which could determine late genetic effects, and should therefore be carefully considered in the evaluation of risk for space missions.

Cell-cycle stage radiosensitivity for the induction of chromosome aberrations has been investigated in C3H 10T1/2 cells. Exponentially growing cells were irradiated with 3 Gy X-rays (80 kVp) or 0.6 Gy alpha-particles (LET = 101 keV/micron). The two doses produce the same survival level (37%) in the asynchronous population. Cells were harvested at four different times following irradiation and cell-cycle phase at the time of irradiation was assessed by using the differential replication staining technique. The frequency of chromosome aberrations produced in a given stage of the cell cycle was not constant as a function of the sampling time, but this could not be simply related to the existence of subphases exhibiting different radiosensitivity, because of cell-cycle perturbation introduced by radiation. X-radiation induced more exchanges than deletions, whereas a predominance of isochromatid deletions was observed after alpha-irradiation. This can be interpreted on the basis of the different patterns of energy deposition of densely- and sparsely-ionizing radiation. Both X- and alpha-rays produced a significant increase in the frequency of Robertsonian translocations when cells were exposed in G1 or S phase, but not in G2 phase.

Inactivation of mouse C3H 10t1/2 cells in plateau-phase (7.8 × 104 cells/cm2) was studied by using αparticles from the irradiation facility installed for radiobiological experiments at the 3 MV Tandem accelerator, University of Naples. Silicon detectors and CR39 plastic track detectors were employed for dosimetric purposes. The cells were exposed to high LET monoenergetic αparticles (energy of 1.8 MeV at the centre of the cell nucleus, track-averaged LET of 177 keV/μm and dose-rate of 1.1 Gy/min) and low-LET 80 kVp X-rays. The X-ray survival curve showed a significant shoulder (αbeta; = 9 Gy) while the survival curve for αparticles was close to exponential. The mean lethal dose of αparticles was 0.77 ± 0.02 Gy and the RBE was 5.2 at 80% survival and 3.0 at 5% survival. Survival of exponentially growing cells (2 × 104 cells/cm2) following irradiation with the αparticle beam is also reported. The nuclear areas of 10T1/2 cells were measured as 299 ± 9 μm2 and 250 ± 8 μm2 for cells in log phase and plateau phase, respectively. The inactivation cross-section, obtained from the mean lethal dose, was 34 μm2 and 37 μm2 for cells in log phase and plateau phase, respectively. These values appear to be the maximum measured values for the inactivation cross-section of 10T1/2 cells as a function of the αparticle LET. This saturation cross-section is very similar to the saturation values reported in the literature for other mammalian cell lines. © 1992 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

Membrane electrical properties of mouse embryo fibroblasts and their ionizing radiation and chemically transformed counterparts were investigated using dielectric relaxation measurements in the radio frequency range. This determination is possible because, in the radio frequency range, suspensions of cells in an electrolyte buffer show a conductivity dispersion due to interfacial polarization. An analysis of the experimental data based on a "single-shell" model showed that conductivity and permittivity of the membranes of both radiation and chemically transformed fibroblasts were lower than in normal cells. In addition, the conductivity of the cytoplasm was higher in both transformed cell types than in the normal mouse fibroblasts. We discuss the significance of these findings in view of the possible structural and functional modifications brought about by the process of neoplastic transformation.

The bacterial enzyme PvuII, which generates blunt-ended DNA double-strand breaks, and T4 DNA ligase, which seals adjacent DNA fragments in coupling to ATP cleavage, were introduced in mouse C3H10T1/2 fibroblasts using osmolytic shock of pinocytic vesicles. Cells were then assayed for their clonogenic ability. In agreement with previous studies by others, we find that the PvuII restriction endonuclease simulates ionizing radiation effects by causing a dose-dependent loss of reproductive capacity. Here we show that the concomitant treatment with DNA ligase considerably increases cell survival. Survival curves were shown to be dependent on the ligase enzyme dose and on ATP concentration in the hypertonic medium. We conclude that T4 DNA ligase is able to repair some of the potentially lethal damage produced by restriction endonucleases in eucaryotic cells. © 1991 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

The mean survival doses of T4 bacteriophage irradiated in suspension by protons were measured at six values of incident energy. Due to the thickness of the target, the beam stopped inside the suspension, so yielding the overall mean dose, averaged from the incident energy to zero. By a suitable analysis of the overall mean doses, measured at different incident energies, the mean doses in narrow intervals of energy, which may be related to definite LET values, were extracted.

Mean doses for damage induced by 3.7-MeV protons in T4 phage were measured for the following effects: inactivation, killing, adsorption, DNA injection, capsid rupture with DNA release, and single- and double-strand DNA breaks. These effects have been related to phage survival in the same experiment because of the variability inherent in such measurements. The experiments were carried out in nutrient broth, phosphate buffer, and phosphate buffer plus histidine as suspension media. The following conclusions can be drawn: (i) DNA double-strand breakage is the dominant cause of inactivation in nutrient broth; (ii) scavengers protect the DNA inside the capsid to only a small degree; (iii) indirect actions affect functions associated with proteins; (iv) DNA release, as measured by capsid rupture, accounts for only a small percentage of the loss of viability; (v) essentially all DNA from adsorbed phage is injected even though a large proportion of the DNA contains double-strand breaks.

We studied the effect of gestational age and maturity on plasma zinc and copper levels at 10 and 120 days of age. The association of plasma zinc changes and body growth was also investigated. Infants were receiving a controlled intake of zinc and copper solely through a zinc-supplemented formula (4.7 mg/L of zinc and 0.16 mg/L of copper). Twenty-eight low-birthweight infants (less than 2,500 g) having gestational ages ranging from 33 to 40 weeks [17 with an appropriate birthweight for gestational age (AGA) and 11 small for gestational age (SGA)] were enrolled in the present study. Measurements of plasma zinc and copper concentration, weight, length, head circumference, and tricipital and subscapular skinfolds were carried out at 10 and 120 days of age. Proton-induced x-ray fluorescence technique (PIXE) was used to assess copper and zinc concentrations. At 10 days of age a significant correlation between copper concentration and gestational age was found. At 120 days of age the copper concentration was higher than at 10 days and independent of gestational age and maturity (mean +/- SEM = 116 +/- 5 micrograms/dl). At 10 days of age no significant correlation between zinc content and gestational age was found (86 +/- 4 micrograms/dl). The plasma zinc percent change over the period from 10 to 120 days of age was positively correlated with gestational age in the whole sample as well as in AGA and SGA infants separately.(ABSTRACT TRUNCATED AT 250 WORDS)

We isolated and characterized a type B thymotropic retrovirus (DMBA-LV) which is highly related to mouse mammary tumor virus (MMTV) isolates and which induces T-cell thymomas with a high incidence and a very short latent period. Regions of nonhomology between the DMBA-LV genome and the MMTV genome were identified by heteroduplex mapping and nucleotide sequence studies. In the electron microscope heteroduplex mapping studies the EcoRI-generated 5' and 3' fragments of the DMBA-LV genome were compared with the corresponding fragments of the MMTV (C3H and GR) genome isolated from mammary tumors. The results indicated that DMBA-LV contained a region of nonhomologous nucleotide sequences in the 3' half of the U3 region of the long terminal repeat (LTR). Nucleotide sequence studies confirmed these results and showed that in this region 440 nucleotides of the MMTV (C3H) sequences were deleted and substituted with a segment of 122 nucleotides. This substituted segment in the form of a tandem repeat structure contained nucleotide sequences derived exclusively from sequences which flanked the substitution loop. The distal glucocorticoid regulatory element was unaltered, and two additional copies of the distal glucocorticoid regulatory element-binding site were present in the substituted region. The restriction endonuclease map of the reconstructed molecular clone of DMBA-LV was identical to that corresponding to unintegrated linear DMBA-LV DNA present in DMBA-LV-induced tumor cell lines. Since the nucleotide sequences of the LTRs present in four different DMBA-LV proviral copies isolated from a single thymoma were identical, we concluded that they were derived from the same parental virus and that this type B retrovirus containing an alteration in the U3 region of its LTR could induce thymic lymphomas. Thus, DMBA-LV represents the first example of a productively replicating type B retrovirus that contains an LTR modified in the U3 region and that has target cell and disease specificity for T cells.

Dose-response curves were measured for the induction of chromosomal aberrations in peripheral blood lymphocytes after acute exposure in vitro to 60Co gamma rays. Blood was obtained from four different healthy donors, and chromosomes were either observed at metaphase, following colcemid accumulation, or prematurely condensed by calyculin A. Cells were analysed in three different Italian laboratories. Chromosomes 1, 2, and 4 were painted, and simple-type interchanges between painted and non-painted chromosomes were scored in cells exposed in the dose range 0.1-3.0 Gy. The chemical-induced premature chromosome condensation method was also used combined with chromosome painting (chromosome 4 only) to determine calibration curves for high dose exposures (up to 20 Gy X rays). Calibration curves described in this paper will be used in our laboratories for biological dosimetry by fluorescence in situ hybridisation.