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Recent occurrences of filoviruses and the arenavirus Lassa virus (LASV) in overlapping endemic areas of Africa highlight the need for a prophylactic vaccine that would confer protection against all of these viruses that cause lethal hemorrhagic fever (HF). We developed a quadrivalent formulation of VesiculoVax that contains recombinant vesicular stomatitis virus (rVSV) vectors expressing filovirus glycoproteins and that also contains a rVSV vector expressing the glycoprotein of a lineage IV strain of LASV. Cynomolgus macaques were vaccinated twice with the quadrivalent formulation, followed by challenge 28 days after the boost vaccination with each of the 3 corresponding filoviruses (Ebola, Sudan, Marburg) or a heterologous contemporary lineage II strain of LASV. Serum IgG and neutralizing antibody responses specific for all 4 glycoproteins were detected in all vaccinated animals. A modest and balanced cell-mediated immune response specific for the glycoproteins was also detected in most of the vaccinated macaques. Regardless of the level of total glycoprotein-specific immune response detected after vaccination, all immunized animals were protected from disease and death following lethal challenges. These findings indicate that vaccination with attenuated rVSV vectors each expressing a single HF virus glycoprotein may provide protection against those filoviruses and LASV most commonly responsible for outbreaks of severe HF in Africa.

Background Currently, there is no consensus on the most appropriate post-operative management for patients undergoing total ankle arthroplasty. The aim of this study is therefore to offer a systematic review of the pertaining literature to identify current post-operative protocols and describe possible differences. Methods A systematic review to identify recent studies concerning the post-operative management after total ankle arthroplasty was conducted. Five topics were analyzed: length of hospital stay, type and duration of immobilization, weight-bearing management, post-operative pharmacological therapies, adopted rehabilitation scheme. Results Eighty-four studies met the inclusion criteria and were included in the review process. Most of the papers appear to have conflicting opinions with no consensus and homogeneous protocols. Conclusion Due to various methodological limitations, it is not possible to provide sufficiently supported evidence-based recommendations, and it is therefore difficult to determine the superiority of one post-operative protocol over the others after total ankle arthroplasty.

Postexposure immunization can prevent disease and reduce transmission following pathogen exposure. The rapid immunostimulatory properties of recombinant vesicular stomatitis virus (rVSV)-based vaccines make them suitable postexposure treatments against the filoviruses Ebola virus and Marburg virus (MARV); however, the mechanisms that drive this protection are undefined. Previously, we reported 60–75% survival of rhesus macaques treated with rVSV vectors expressing MARV glycoprotein (GP) 20–30 minutes after a low dose exposure to the most pathogenic variant of MARV, Angola. Survival in this model was linked to production of GP-specific antibodies and lower viral load. To confirm these results and potentially identify novel correlates of postexposure protection, we performed a similar experiment, but analyzed plasma cytokine levels, frequencies of immune cell subsets, and the transcriptional response to infection in peripheral blood. In surviving macaques (80–89%), we observed induction of genes mapping to antiviral and interferon-related pathways early after treatment and a higher percentage of T helper 1 (Th1) and NK cells. In contrast, the response of non-surviving macaques was characterized by hypercytokinemia; a T helper 2 signature; recruitment of low HLA-DR expressing monocytes and regulatory T-cells; and transcription of immune checkpoint (e.g., PD-1, LAG3) genes. These results suggest dysregulated immunoregulation is associated with poor prognosis, whereas early innate signaling and Th1-skewed immunity are important for survival.

Summary Background The safety and immunogenicity of a highly attenuated recombinant vesicular stomatitis virus (rVSV) expressing HIV-1 gag (rVSVN4CT1-HIV-1gag1) was shown in previous phase 1 clinical studies. An rVSV vector expressing Ebola virus glycoprotein (EBOV-GP) in place of HIV-1 gag (rVSVN4CT1-EBOVGP1) showed single-dose protection from lethal challenge with low passage Ebola virus in non-human primates. We aimed to evaluate the safety and immunogenicity of the rVSVN4CT1-EBOVGP1 vaccine in healthy adults. Methods We did a randomised double-blind, placebo-controlled, phase 1 dose-escalation study at a single clinical site (Optimal Research) in Melbourne, FL, USA. Eligible participants were healthy men and non-pregnant women aged 18–60 years, with a body-mass index (BMI) of less than 40 kg/m2, no history of filovirus infection, VSV infection, or receipt of rVSV in previous studies, and who had not visited regions where Ebola virus outbreaks have occurred. Three cohorts were enrolled to assess a low (2·5 × 104 plaque forming units [PFU]), intermediate (2 × 105 PFU), or high dose (1·8 × 106 PFU) of the vaccine. Participants within each cohort were randomly allocated (10:3) to receive vaccine or placebo by intramuscular injection in a homologous prime and boost regimen, with 4 weeks between doses. All syringes were masked with syringe sleeves; participants and study site staff were not blinded to dose level but were blinded to active vaccine and placebo. The primary outcomes were safety and tolerability; immunogenicity, assessed as GP-specific humoral immune response (at 2 weeks after each dose) and cellular immune response (at 1 and 2 weeks after each dose), was a secondary outcome. All randomised participants were included in primary and safety analyses. This trial is registered with ClinicalTrials.gov , NCT02718469 . Findings Between Dec 22, 2015, and Sept 15, 2016, 39 individuals (18 [46%] men and 21 [54%] women, mean age 51 years [SD 10]) were enrolled, with ten participants receiving the vaccine and three participants receiving placebo in each of three cohorts. One participant in the intermediate dose cohort was withdrawn from the study because of a diagnosis of invasive ductal breast carcinoma 24 days after the first vaccination, which was considered unrelated to the vaccine. No severe adverse events were observed. Solicited local adverse events occurred in ten (26%) of 39 participants after the first dose and nine (24%) of 38 participants after the second dose; the events lasted 3 days or less, were predominantly injection site tenderness (17 events) and injection site pain (ten events), and were either mild (19 events) or moderate (ten events) in intensity. Systemic adverse events occurred in 13 (33%) of 39 participants after the first dose and eight (21%) of 38 participants after the second dose; the events were mild (45 events) or moderate (11 events) in severity, and the most common events were malaise or fatigue (13 events) and headache (12 events). Arthritis and maculopapular, vesicular, or purpuric rash distal to the vaccination site(s) were not reported. A GP-specific IgG response was detected in all vaccine recipients after two doses (and IgG response frequency was 100% after a single high dose), and an Ebola virus neutralising response was detected in 100% of participants in the high-dose cohort. Interpretation The rVSVN4CT1-EBOVGP1 vaccine was well tolerated at all dose levels tested and was immunogenic despite a high degree of attenuation. The combined safety and immunogenicity profile of the rVSVN4CT1-EBOVGP1 vaccine vector support phase 1–2 clinical evaluation. Funding US Department of Defense Joint Program Executive Office for Chemical, Biological, Radiological and Nuclear Defense: Joint Project Manager for Chemical, Biological, Radiological and Nuclear Medical.

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).

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 4)He(2+) 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.

Telomere integrity is important for chromosome stability. The main objective of our study was to investigate the relationship between telomere length modulation and mitotic chromosome segregation induced by ionizing radiation in human primary fibroblasts. We used X-rays and low-energy protons because of their ability to induce different telomeric responses. Samples irradiated with 4 Gy were fixed at different times up to 6 days from exposure and telomere length, anaphase abnormalities, and chromosome aberrations were analyzed. We observed that X-rays induced telomere shortening in cells harvested at 96 hrs, whereas protons induced a significant increase in telomere length at short as well as at long harvesting times (24 and 96 hrs). Consistent with this, the analysis of anaphase bridges at 96 hrs showed a fourfold increase in X-ray- compared with proton-irradiated samples, suggesting a correlation between telomere length/dysfunction and chromosome missegregation. In line with these findings, the frequency of dicentrics and rings decreased with time for protons whereas it remained stable after X-rays irradiation. Telomeric FISH staining on anaphases revealed a higher percentage of bridges with telomere signals in X-ray-treated samples than that observed after proton irradiation, thus suggesting that the aberrations observed after X-ray irradiation originated from telomere attrition and consequent chromosome end-to-end fusion. This study shows that, beside an expected "early" chromosome instability induced shortly after irradiation, a delayed one occurs as a result of alterations in telomere metabolism and that this mechanism may play an important role in genomic stability.

The radiation induced free radical damage in Chinese hamster lung fibroblast V-79 cells stored in DMEM culture medium containing 10% DMSO has been investigated by matrix EPR spectroscopy in connection with the H2O/DMSO binary phase diagram. A major part of the indirect effect is due to radicals from the DMSO·3H2O phase in the freezing medium, which are released on warming in the temperature range between 130 K and 160 K, that is, far below the eutectic melting temperature (210 K). The radicals trapped in the DMSO·3H2O phase react with oxygen above 160 K giving reactive oxygen species (ROS) of the type of peroxyl radicals. A lower limit yield of 10–15% was calculated for this conversion. Scavenging experiments with a stable nitroxyl radical (tempol) have demonstrated that part of the DMSO·3H2O radicals escape by mutual recombination on melting and are therefore available for inducing indirect cell damage. The same experiments performed with pure frozen water have shown that OH radicals are not available for inducing cell damage. The EPR measurements performed on H2O/DMSO frozen mixtures suggest that the radiation induced radical forming process does not change when passing to the low dose range below 1 Gy, in agreement with the linear model.

A growing body of experimental evidence gathered in the last 10-15 years with regard to targeted and non-targeted effects of low doses of ionizing radiation (hyper-radiosensitivity, induced radio-resistance, adaptive response, genomic instability, bystander effects) has pushed the radiobiology research towards a better understanding of the mechanisms underlying these phenomena, the extent to which they are active in-vivo, and how they are inter-related. In such a way factors could be obtained and included in the estimation of potential cancer risk to the human population of exposure to low levels of ionizing radiation. Different experimental approaches have been developed and employed to study such effects in-vitro (medium transfer experiments; broad-field irradiation at low doses also with insert or shielding systems...). In this regard, important contributions came from ionizing radiation microbeam facilities that turn to be powerful tools to perform selective irradiations of individual cells inside a population with an exact, defined and reproducible dose (i.e. number of particles, in case of charged particle microbeams). Over the last 20 years the use of microbeams for radiobiological applications increased substantially and a continuously growing number of such facilities, providing X-rays, electrons, light and heavy ions, has been developing all over the world. Nowadays, just in Europe there are 12 microbeam facilities fully-operational or under-development, out of more than 30 worldwide. An overview of the European microbeam facilities for radiobiological studies is presented and discussed in this paper.

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 4)He(2+) 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.

The spatial distribution of radiation-induced DNA breaks within the cell nucleus depends on radiation quality in terms of energy deposition pattern. It is generally assumed that the higher the radiation linear energy transfer (LET), the greater the DNA damage complexity. Using a combined experimental and theoretical approach, we examined the phosphorylation-dephosphorylation kinetics of radiation-induced γ-H2AX foci, size distribution and 3D focus morphology, and the relationship between DNA damage and cellular end points (i.e., cell killing and lethal mutations) after exposure to gamma rays, protons, carbon ions and alpha particles. Our results showed that the maximum number of foci are reached 30 min postirradiation for all radiation types. However, the number of foci after 0.5 Gy of each radiation type was different with gamma rays, protons, carbon ions and alpha particles inducing 12.64 ± 0.25, 10.11 ± 0.40, 8.84 ± 0.56 and 4.80 ± 0.35 foci, respectively, which indicated a clear influence of the track structure and fluence on the numbers of foci induced after a dose of 0.5 Gy for each radiation type. The γ-H2AX foci persistence was also dependent on radiation quality, i.e., the higher the LET, the longer the foci persisted in the cell nucleus. The γ-H2AX time course was compared with cell killing and lethal mutation and the results highlighted a correlation between cellular end points and the duration of γ-H2AX foci persistence. A model was developed to evaluate the probability that multiple DSBs reside in the same gamma-ray focus and such probability was found to be negligible for doses lower than 1 Gy. Our model provides evidence that the DSBs inside complex foci, such as those induced by alpha particles, are not processed independently or with the same time constant. The combination of experimental, theoretical and simulation data supports the hypothesis of an interdependent processing of closely associated DSBs, possibly associated with a diminished correct repair capability, which affects cell killing and lethal mutation.

Practical assessment of human radiation exposure risk deserves particular attention especially for low doses (and low dose rates), which concern environmental and occupational exposure. At these dose levels ionizing radiation exposures involve mainly isolated charged particle tracks, which strike individual cells at time intervals averaging from weeks to several years apart. Accelerator-based microbeam irradiation technique offers a unique tool to mimic such an exposure, allowing irradiating single cells individually with micrometer precision and with a preset number of charged particles down to one particle per cell. A horizontal single-ion microbeam facility for single-cell irradiations has been designed and set up at the INFN-LNL 7MV CN Van de Graaff accelerator. The light ion beam is collimated in air down to a section of 2-3µm in diameter by means of appropriate pinholes. Semi-automatic cell visualization and automatic cell positioning and revisiting system, based on an inverted phase contrast optical microscope and on X-Y translation stages with 0.1µm positioning precision, has been developed. An in-house-written software allows to control remotely the irradiation protocol. As a distinctive feature of the facility, cell recognition is performed without using fluorescent staining and UV light. Particle detection in air, behind the biological sample, is based on a silicon detector while in-air beam profile and precise hit position measurements are accomplished by a custom-made cooled-CCD camera and Solid State Nuclear Track detectors, respectively. A particle counting rate of less than 1 ion/sec can be reached.

Charged-particle microbeams are unique tools to mimic low-dose exposure in vitro by delivering a defined number of particles to single mammalian cells down to only one particle per cell or group of cells. A horizontal single-ion microbeam facility has been built at the INFN-Laboratori Nazionali di Legnaro 7 MV Van de Graaff accelerator. Different light ions (1H+, 2H+, 3He2+, 4He2+) are available covering a wide range of LET from 7 to 150 keV/microm. Collimators of different geometries and materials have been tested, and beam spots 2-3 microm in diameter have been obtained using a tantalum disc. Cell visualization and recognition are performed with a phase-contrast optical microscope coupled with dedicated software. One unique characteristic of such a system is that neither cell staining nor UV light is used. Cells are automatically positioned on the beam spot through remotely controlled precision XY translation stages. A particle detector is positioned downstream of a specially designed petri dish to perform energy measurements and count particles crossing the cell. A particle counting rate of less than 1 ion/s can be reached. This feature, combined with a fast beam deflection system, ensures high reproducibility in administering a preset number of particles per cell.

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.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).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.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.

High-resolution multicolour banding FISH (mBAND) and multiplex FISH (mFISH) were used to analyse the aberrations of chromosome 1 in irradiated-AG01522 human primary fibroblasts. The cells were exposed to 1Gy of a panel of radiation of different qualities, such as X-rays, low-energy protons (28keV/μm), helium-ions (62keV/μm) and carbon-ions (96 and 252keV/μm). mBAND and mFISH analysis in calyculin-A G2-condensed chromosome spreads allowed us to detect intra- and interchromosome aberrations involving chromosome 1, including simple and complex-type exchanges, inversions (both para- and pericentric ones), deletions and rings. The data indicate that the induction of chromosomal exchanges was influenced by both Linear energy transfer (LET) and particle types. Moreover, the complex-to-simple exchanges ratio (C-ratio) and interchromosome to intrachromosome exchanges ratio (F-ratio) were evaluated by mFISH and mBAND techniques, respectively. Our results indicate that the C-ratio is a more reliable marker of radiation quality, with values that increased linearly in an LET-dependent manner. In addition, by means of mBAND analysis, the distribution of radiation-induced breakpoints along chromosome 1 was analyzed and compared with the expected distributions of the breaks. The expected values were calculated assuming a random distribution of the breakpoints. The data indicate that, irrespective of the radiation that was used, the breakpoints were non-randomly distributed along chromosome 1. In particular, breaks in the pericentromeric region were encountered at a higher frequency than expected. A deeper analysis revealed that breaks were not located in the constitutive heterochromatin (G-bands 1p11/1q11 and 1q12), but rather in a region comprised between 1p11.2 and 1p22.1, which includes G-light and G-dark bands.

This work aimed at measuring cell-killing effectiveness of monoenergetic and Spread-Out Bragg Peak (SOBP) carbon-ion beams in normal and tumour cells with different radiation sensitivity. Clonogenic survival was assayed in normal and tumour human cell lines exhibiting different radiosensitivity to X- or γ-rays following exposure to monoenergetic carbon-ion beams (incident LET 13–303 keV/μm) and at various positions along the ionization curve of a therapeutic carbon-ion beam, corresponding to three dose-averaged LET (LETd) values (40, 50 and 75 keV/μm). Chinese hamster V79 cells were also used. Carbon-ioneffectiveness for cell inactivation generally increased with LET for monoenergetic beams, with the largest gain in cell-killing obtained in the cells most radioresistant to X- or γ-rays. Such an increased effectiveness in cells less responsive to low LET radiation was found also for SOBP irradiation, but the latter was less effective compared with monoenergetic ion beams of the same LET. Our data show the superior effectiveness for cell-killing exhibited by carbon-ion beams compared to lower LET radiation, particularly in tumour cells radioresistant to X- or γ-rays, hence the advantage of using such beams in radiotherapy. The observed lower effectiveness of SOBP irradiation compared to monoenergetic carbon beam irradiation argues against the radiobiological equivalence between dose-averaged LET in a point in the SOBP and the corresponding monoenergetic beams.

Mitochondria are the main cellular source of Reactive Oxygen Species (ROS). Alterations of mitochondrial metabolism and consequent loss of mitochondrial membrane potential may lead to redox imbalance and in turn to DNA damage, chromosomal instability and apoptosis. On the other hand, impaired mitochondrial functions may either exacerbate the detrimental effects of geno- and cytotoxic agents or may bring beneficial cellular responses. To study the role of mitochondria within this framework, AG01522 human primary fibroblasts were incubated with the mitochondrial polymerase γ inhibitor 2',3'-dideoxycytidine (ddC), leading to mitochondrial DNA (mtDNA) depletion and to mitochondrial dysfunctions. The successful treatment toward mtDNA depletion was confirmed by Complex-IV subunit I (COX-I) immunofluorescence and western blot assays. mtDNA-depleted cells and their counterparts were ultrastructurally characterized by transmission electron microscopy. mtDNA-depleted cells showed dramatic mitochondrial alterations such as fragmentation and cristae disruption along with a reduction of the mitochondrial membrane potential and elevated levels of ROS. Despite increased ROS levels, we did not find any difference in telomere length between ddC-treated and untreated cells. The spontaneous rate of DNA double-strand breaks (DSBs) and chromosome aberrations was significantly enhanced in mtDNA-depleted cells whereas the induction of DSBs by low-Linear Energy Transfer (LET) (X-rays; 7.7keV/μm protons) and high-LET radiations (28.5keV/μm protons) did not differ when compared with normal cells. However, in irradiated cells impaired mitochondrial functions seemed to bring beneficial cellular responses to the detrimental effect of radiations. In fact, after X-irradiation mtDNA-depleted cells show less remaining unrejoined DSBs than normal cells and furthermore a lower induction of cytogenetic damage. Overall, these data show that active mitochondrial functions are required for the proper maintenance of cellular genome stability in primary fibroblasts.

""Purpose: Biological effects produced by low doses of ionizing radiations, though relevant for the risk assessment, have not been fully elucidated. The aim of the present work was to evaluate cytogenetic endpoints, as telomere dysfunctions and chromosome instability in the low-dose range as a function of radiation quality. In particular, we analyzed whether the telomere length was modulated, as well as the involvement of telomeres in chromosomal alterations at anaphase, and the yield of stable simple and complex chromosome aberrations. Materials and methods: AG01522 human primary fibroblasts were irradiated with 0.1-1 Gy of X-rays, protons (28.5 keV\\\/μm), and 4He2+ ions (62 keV\\\/μm). Frequency of chromosome bridges carrying or not telomeric signals and telomere length were measured in irradiated samples up to 72 h. Moreover, chromosome instability was measured using multicolor fluorescence in situ hybridization (mFISH). Results: The results evidenced a linear energy transfer (LET)- and dose-dependent response in the frequency of anaphase bridges induction and in their persistence as a function of time. However, neither variation in telomere length and telomere loss, nor in the proportion of bridges bearing telomeric signals, was detected, thus indicating a minor role of telomeres in the generation of the radiation-induced chromosome bridges. Chromosome instability followed a linear-dependence with dose and LET, showing a far higher extent of complex translocations in helium-ion-irradiated cells than in proton- or X-ray-irradiated samples. Conclusions: Altogether, the results indicated the lack of telomere involvement in cytogenetic effects induced by low-dose ionizing radiation. On the contrary, chromosome aberration yield and spectrum were LET- and dose-dependent.. . ""

This paper presents 12 facts about the mortgage market. The authors argue that the facts refute the popular story that the crisis resulted from financial industry insiders deceiving uninformed mortgage borrowers and investors. Instead, they argue that borrowers and investors made decisions that were rational and logical given their ex post overly optimistic beliefs about house prices. The authors then show that neither institutional features of the mortgage market nor financial innovations are any more likely to explain those distorted beliefs than they are to explain the Dutch tulip bubble 400 years ago. Economists should acknowledge the limits of our understanding of asset price bubbles and design policies accordingly.

In a recent set of influential papers, researchers have argued that residential mortgage foreclosures reduce the sale prices of nearby properties. We revisit this issue using a more robust identification strategy combined with new data that contain information on the location of properties secured by seriously delinquent mortgages and information on the condition of foreclosed properties. We find that while properties in virtually all stages of distress have statistically significant, negative effects on nearby home values, the magnitudes are economically small, peak before the distressed properties complete the foreclosure process, and go to zero about a year after the bank sells the property to a new homeowner. The estimates are very sensitive to the condition of the distressed property, with a positive correlation existing between house price growth and foreclosed properties identified as being in "above average" condition. We argue that the most plausible explanation for these results is an externality resulting from reduced investment by owners of distressed property. Our analysis shows that policies that slow the transition from delinquency to foreclosure likely exacerbate the negative effect of mortgage distress on house prices.

Many have argued that laws that give borrowers additional rights can help prevent unnecessary foreclosures by giving borrowers more time to cure their delinquencies or by facilitating workouts. We first compare states that allow power-of-sale foreclosures with states that do not and find that preventing power-of-sale foreclosures extends the foreclosure timeline dramatically but does not, in the long run, lead to fewer foreclosures. Borrowers in states that allow power-of-sale foreclosure are no less likely to cure and no less likely to renegotiate their loans. We then exploit a "right-to-cure" law instituted in Massachusetts in May 2008. We employ a differences-in-differences approach to evaluate the effect of the policy, comparing Massachusetts with neighboring states that did not adopt such laws. We find that the right-to-cure law lengthens the foreclosure timeline but does not lead to better outcomes for borrowers.

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.

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.

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.

We analyze price dispersion in the airline industry in order to determine the e®ects of the business cycle on markup variations. We ¯nd that the cycle can a®ect the degree to which airlines can price discriminate between di®erent consumer types, ultimately a®ecting the degree of price dispersion. Performing a ¯xed-e®ects panel analysis on 17 years of data covering two business cycles, we ¯nd that price dispersion is highly procyclical. Estimates show that a rise in the output gap of one percentage point increases the interquartile range by 1.6 percent. These results suggest that markups move procyclically in the airline industry, such that during booms in the cycle, the ¯rm can signi¯cantly raise the markup charged to those with high willingness to pay. Our analysis suggests that this impact on the ¯rm's ability to price discriminate imposes extra pro¯t risk to the ¯rm over and above cost variations.

It is well established that high-LET radiations efficiently induce chromosome aberrations. However, data on the effect of protons on telomere maintenance, as involved in genomic stability, are scarce and contradictory. Here we demonstrate that high-LET protons induce telomere lengthening in human primary fibroblasts and that this elongation does not involve the telomerase enzyme, supporting the hypothesis that high-LET radiations are able to activate a telomerase-independent mechanism. In tumor cells that lack telomerase, one or more non-telomerase mechanisms for telomere maintenance are present, which are termed alternative lengthening of telomeres (ALT). Since ALT cells are characterized by recombinational events at telomeres, known as telomeric-sister chromatid exchanges (T-SCE), and colocalization of telomeres and premyelocytic leukemia protein (PML), we analyzed both T-SCE and PML. Our results show that high-LET protons induce a 2.5-fold increase of T-SCE and a colocalization of PML protein and telomeric DNA. Furthermore, our data show that the ALT pathway can be activated in human primary cells after induction of severe DNA damage. Thus, since telomeres are known to be involved in chromosome maintenance, the present work may contribute in the elucidation of the mechanism by which ionizing radiation induces genomic instability.

In 2007, the United States began to experience its worst housing and foreclosure crisis since the Great Depression. In response, policymakers have been devising foreclosure prevention plans, most of which focus on loan modifications. ; This article begins with an overview of the different loss mitigation tools that mortgage lenders and policymakers have used in the past to combat foreclosure and then briefly summarizes the main U.S. programs of the past few years. By most analyses, the authors note, these recent programs have had poor results in terms of significantly reducing foreclosures, and borrowers who have received modifications are redefaulting at extremely high rates. ; The authors then review both the theoretical academic literature of the 1990s and early 2000s and the more recent empirical literature generated by the recent foreclosure crisis. Many of the recent studies have focused on loan modification as a loss mitigation tool. ; Given the limited success of government loan modification programs, the authors believe that policymakers will likely turn their attention to other alternatives. The authors point to signs that the focus is now shifting to programs that do not attempt to prevent foreclosures but rather try to help homeowners who have already experienced foreclosure.

The exact cause of the massive defaults and foreclosures in the U.S. subprime mortgage market is still unclear. This paper investigates whether a particular aspect of borrowers' financial literacy—their numerical ability—may have played a role. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out mortgages in 2006 or 2007 and match these measures to objective data on mortgage characteristics and repayment performance. We find a large and statistically significant negative correlation between numerical ability and various measures of delinquency and default. Foreclosure starts are approximately two-thirds lower in the group with the highest measured level of numerical ability compared with the group with the lowest measured level. The result is robust to controlling for a broad set of sociodemographic variables and not driven by other aspects of cognitive ability or the characteristics of the mortgage contracts. Our results raise the possibility that limitations in certain aspects of financial literacy played an important role in the subprime mortgage crisis.

Understanding the evolution of real-time beliefs about house price appreciation is central to understanding the U.S. housing crisis. At the peak of the recent housing cycle, both borrowers and lenders appealed to optimistic house price forecasts to justify undertaking increasingly risky loans. Many observers have argued that these rosy forecasts ignored basic theoretical and empirical evidence that pointed to a massive overvaluation of housing and thus to an inevitable and severe price decline. We revisit the boom years and show that the economics profession provided little such countervailing evidence at the time. Many economists, skeptical that a bubble existed, attempted to justify the historic run-up in housing prices based on housing fundamentals. Other economists were more uncertain, pointing to some evidence of bubble-like behavior in certain regional housing markets. Even these more skeptical economists, however, refused to take a conclusive position on whether a bubble existed. The small number of economists who argued forcefully for a bubble often did so years before the housing market peak, and thus lost a fair amount of credibility, or they make arguments fundamentally at odds with the data even ex post. For example, some economists suggested that cities where new construction was limited by zoning regulations or geography were particularly "bubble-prone," yet the data shows that the cities with the biggest gyrations in house prices were often those at the epicenter of the new construction boom. We conclude by arguing that economic theory provides little guidance as to what should be the "correct" level of asset prices -- including housing prices. Thus, while optimistic forecasts held by many market participants in 2005 turned out to be inaccurate, they were not ex ante unreasonable.

This paper exploits a natural policy experiment to directly identify the crowding out effects of public transfers on the incidence and level of private transfers. The introduction of a large social security program in Taiwan is used to estimate the effect of an exogenous increase in government transfer payments to the elderly on the private transfer behavior of their adult children. Using an instrumental variables strategy that accounts for the endogeneity of receiving public transfers, the empirical results show strong evidence of crowding out on the extensive margin (the probability of providing a positive transfer) and weaker evidence of crowding out on the intensive margin (the amount of the transfer conditional on it being positive).

This paper takes a skeptical look at a leading argument about what is causing the foreclosure crisis and what should be done to stop it. We use an economic model to focus on two key decisions: the borrower’s choice to default on the mortgage and the lender’s choice on whether to renegotiate or “modify” the loan. The theoretical model and econometric analysis illustrate that “unaffordable” loans, defined as those with high mortgage payments relative to income at origination, are unlikely to be the main reason that borrowers decide to default. Rather, the typical problem appears to be a combination of household income shocks and an unprecedented fall in house prices. Regarding the small number of loan modifications to date, we show, both theoretically and empirically, that the efficiency of foreclosure for investors is a more plausible explanation for the low number of modifications than contract frictions related to securitization agreements between servicers and investors. While investors might be foreclosing when it would be socially efficient to modify, there is little evidence to suggest they are acting against their own interests when they do so. An important implication of our analysis is that policies designed to reduce foreclosures should focus on ameliorating the immediate effects of job loss and other adverse life events, rather than modifying loans to make them more “affordable” on a long-term basis.

The effect of graded doses of high-linear energy transfer (LET) low-energy protons to induce cycle perturbations and genotoxic damage was investigated in normal human fibroblasts. Furthermore, such effects were compared with those produced by low-LET radiations. HFFF2, human primary fibroblasts were exposed to either protons (LET = 28.5 keV/microm) or X/gamma-rays, and endpoints related to cell cycle kinetics and DNA damage analysed. Following both type of irradiations, unsynchronized cells suffered an inhibition to entry into S-phase for doses of 1-4 Gy and remained arrested in the G(1)-phase for several days. The levels of induction of regulator proteins, such as TP53 and CDKN1A showed a clear LET-dependence. DSB induction and repair as measured by scoring for gamma-H2AX foci indicated that protons, with respect to X-rays, yielded a lower number of DSBs per Gy, which showed a slower kinetics of disappearance. Such result was in agreement with the extent of MN induction in binucleated cells after X-irradiation. No significant differences between the two types of radiations were observed with the clonogenic assay, resulting anyway the slope of gamma-ray curve higher than that the proton one. In conclusion, in normal human primary fibroblasts cell cycle arrest at the G(1)/S transition can be triggered shortly after irradiation and maintained for several hours post-irradiation of both protons and X-rays. DNA damage produced by protons appears less amenable to be repaired and could be transformed in cytogenetic damage in the form of MN.

Human cell line/Carbon-ion beams/Cell inactivation/Relative Biological Effectiveness (RBE)/Linear Energy Transfer (LET). This work aimed at measuring cell-killing effectiveness of monoenergetic and Spread-Out Bragg Peak ( SOBP) carbon-ion beams in normal and tumour cells with different radiation sensitivity. Clonogenic survival was assayed in normal and tumour human cell lines exhibiting different radiosensitivity to X- or γ-rays following exposure to monoenergetic carbon-ion beams (incident LET 13–303 keV/μm) and at various positions along the ionization curve of a therapeutic carbon-ion beam, corresponding to three doseaveraged LET (LETd) values (40, 50 and 75 keV/μm). Chinese hamster V79 cells were also used. Carbon-ion effectiveness for cell inactivation generally increased with LET for monoenergetic beams, with the largest gain in cell-killing obtained in the cells most radioresistant to X- or γ-rays. Such an increased effectiveness in cells less responsive to low LET radiation was found also for SOBP irradiation, but the latter was less effective compared with monoenergetic ion beams of the same LET. Our data show the superior effectiveness for cell-killing exhibited by carbon-ion beams compared to lower LET radiation, particularly in tum our cells radioresistant to X- or γ-rays, hence the advantage of using such beams in radiotherapy. The observed lower effectiveness of SOBP irradiation compared to monoenergetic carbon beam irradiation argues against the radiobiological equivalence between dose-averaged LET in a point in the SOBP and the corresponding monoenergetic beams.

Using a variety of datasets, we document some basic facts about the current subprime crisis. Many of these facts are applicable to the crisis at a national level, while some illustrate problems relevant only to Massachusetts and New England. We conclude by discussing some outstanding questions about which the data, we believe, are not yet conclusive.

This paper analyzes the impact of the subprime mortgage crisis on urban neighborhoods in Massachusetts. We explore the topic using a data set that matches race and income information from Home Mortgage Disclosure Act data with property-level, transaction data from Massachusetts Registry of Deeds offices. With these data, we show that much of the subprime lending in the state was concentrated in urban neighborhoods and that minority homeownerships created with subprime mortgages have proved exceptionally unstable in the face of rapid price declines. The evidence in Massachusetts suggests that subprime lending did not, as commonly believed, lead to a substantial increase in homeownership by minorities but instead generated turnover in properties owned by minority residents. Furthermore, we argue that the particularly dire foreclosure situation in urban neighborhoods actually makes it somewhat easier for policymakers to provide remedies.

The ballistic superiority of various fabric and resin types was examined using ballistic testing, Instron, and peel test data. All cured samples were made at 1000 p.s.i. for 10 minutes at 105°C except S-M/P panels. The latter were fabricated at 1000 p.s.i. for 10, 20, 30, and 60 minutes at 117°C. Data was insufficient to conclude the superiority of the surface treated laminates. However, it suggests the advantage of 10 minute curing time in S-M/P laminates and clearly points out the better kinetic energy absorption of spectra over kevlar. Yet, kevlar or predominantly kevlar laminates show the best Instron and peel test data.

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.

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.

This paper analyzes the effects of market structure on price dispersion in the airline industry, using panel data from 1993 through 2006. The results found in this paper contrast with those of Borenstein and Rose (1994), who found that price dispersion increases with competition. We find that competition has a negative effect on price dispersion, in line with the textbook treatment of price discrimination. Specifically, the effects of competition on price dispersion are most significant on routes that we identify as having consumers characterized by relatively heterogeneous elasticities of demand. On routes with a more homogenous customer base, the effects of competition on price discrimination are largely insignificant. We conclude from these results that competition acts to erode the ability of a carrier to price discriminate, resulting in reduced overall price dispersion.

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.

At the low doses (and low dose rates) relevant to environmental and occupational radiation exposure (0-50 mSv), which are of practical concern for radiation protection, very few cells in the human organism experience more than one traversal by densely ionising particles in their lifetime, the intervals between the tracks, if any, typically being months or years. The biological effects of exactly one particle are not well known and cannot be simulated in vitro by conventional broad-beam exposures, due to the random Poisson distribution of tracks. Charged particle microbeam facilities are a unique tool that allows targeting of single cells and analysis of the induced damage on a cell-by-cell basis. In the past few years, many charged particle microbeam facilities for radiobiology have come into operation or are under development worldwide. Different experimental designs have been adopted at various laboratories regarding the achievement of micrometre (or sub-micrometre) ion beam size, by mechanical collimation or focusing, particle detection, and cell recognition and positioning systems. The different approaches are reviewed and discussed in this paper.

The U.S. mortgage market has experienced phenomenal change over the last 35 years. Most observers believe that the deregulation of the banking industry and financial markets generally has played an important part in this transformation. One issue that has received particular attention is the role that the housing Government Sponsored Enterprises (GSEs), Fannie Mae and Freddie Mac, have played in the development of a secondary market in mortgages. This paper develops and implements a technique for assessing the impact of changes in the mortgage market on individuals and households. ; Our analysis is based on an implication of the permanent income hypothesis: that the higher a household’s future income, the more it desires to spend and consume, ceteris paribus. If we have perfect credit markets, then desired consumption matches actual consumption and current spending on housing should forecast future income. Since credit market imperfections mute this effect, we can view the strength of the relationship between housing spending and future income as a measure of the “imperfectness” of mortgage markets. Thus, a natural way to determine whether mortgage market developments have actually helped households by decreasing market imperfections is to see whether this link has strengthened over time. ; We implement this framework using panel data going back to 1969. We find that over the past several decades, housing markets have become less imperfect in the sense that households are now more able to buy homes whose values are consistent with their long-term income prospects. However, we find no evidence that the GSEs’ activities have contributed to this phenomenon. This is true whether we look at all homebuyers, or at subsamples of the population whom we might expect to benefit particularly from GSE activity, such as low-income households and first-time homebuyers.