Sluggish dorsally-driven inhibition of return during orthographic processing in adults with dyslexia.

Dyslexia (D) is a neurodevelopmental reading disorder characterized by phonological and orthographic deficits. Before phonological decoding, reading requires a specialized orthographic system for parallel letter processing that assigns letter identities to different spatial locations. The magnocellular-dorsal (MD) stream rapidly process the spatial location of visual stimuli controlling visuo-spatial attention. To investigate the visuo-spatial attention efficiency during orthographic processing, inhibition of return (IOR) was measured in adults with and without D in a lexical decision task. IOR is the delay in responding to stimuli displayed in a cued location after a long cue-target interval. Only adults with D did not showed IOR effect during letter-string recognition, despite the typical left-hemisphere specialization for word identification. A specific deficit in coherent-dot-motion perception confirmed an MD-stream disorder in adults with D. Our results suggest that adults with D might develop an efficient visual word form area, but a dorsal-attentional dysfunction impairs their reading fluency.

Visual motion and rapid auditory processing are solid endophenotypes of developmental dyslexia.

Although a genetic component is known to have an important role in the etiology of developmental dyslexia (DD), we are far from understanding the molecular etiopathogenetic pathways. Reduced measures of neurobiological functioning related to reading (dis)ability, i.e. endophenotypes (EPs), are promising targets for gene finding and the elucidation of the underlying mechanisms. In a sample of 100 nuclear families with DD (229 offspring) and 83 unrelated typical readers, we tested whether a set of well-established, cognitive phenotypes related to DD [i.e. rapid auditory processing (RAP), rapid automatized naming (RAN), multisensory nonspatial attention and visual motion processing] fulfilled the criteria of the EP construct. Visual motion and RAP satisfied all testable criteria (i.e. they are heritable, associate with the disorder, co-segregate with the disorder within a family and represent reproducible measures) and are therefore solid EPs of DD. Multisensory nonspatial attention satisfied three of four criteria (i.e. it associates with the disorder, co-segregates with the disorder within a family and represents a reproducible measure) and is therefore a potential EP for DD. Rapid automatized naming is heritable but does not meet other criteria of the EP construct. We provide the first evidence of a methodologically and statistically sound approach for identifying EPs for DD to be exploited as a solid alternative basis to clinical phenotypes in neuroscience.

In vivo radiobiological assessment of the new clinical carbon ion beams at CNAO.

In this article, the in vivo study performed to evaluate the uniformity of biological doses within an hypothetical target volume and calculate the values of relative biological effectiveness (RBE) at different depths in the spread-out Bragg peak (SOBP) of the new CNAO (National Centre for Oncological Hadrontherapy) carbon beams is presented, in the framework of a typical radiobiological beam calibration procedure. The RBE values (relative to (60)Co γ rays) of the CNAO active scanning carbon ion beams were determined using jejunal crypt regeneration in mice as biological system at the entrance, centre and distal end of a 6-cm SOBP. The RBE values calculated from the iso-effective doses to reduce crypt survival per circumference to 10, ranged from 1.52 at the middle of the SOBP to 1.75 at the distal position and are in agreement with those previously reported from other carbon ion facilities. In conclusion, this first set of in vivo experiments shows that the CNAO carbon beam is radiobiologically comparable with the NIRS (National Institute of Radiological Sciences, Chiba, Japan) and GSI (Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany) ones.

Early effects comparison of X-rays delivered at high-dose-rate pulses by a plasma focus device and at low dose rate on human tumour cells.

A comparative study has been performed on the effects of high-dose-rate (DR) X-ray beams produced by a plasma focus device (PFMA-3), to exploit its potential medical applications (e.g. radiotherapy), and low-DR X-ray beams produced by a conventional source (XRT). Experiments have been performed at 0.5 and 2 Gy doses on a human glioblastoma cell line (T98G). Cell proliferation rate and potassium outward currents (IK) have been investigated by time lapse imaging and patch clamp recordings. The results showed that PFMA-3 irradiation has a greater capability to reduce the proliferation rate activity with respect to XRT, while it does not affect IK of T98G cells at any of the dose levels tested. XRT irradiation significantly reduces the mean IK amplitude of T98G cells only at 0.5 Gy. This work confirms that the DR, and therefore the source of radiation, is crucial for the planning and optimisation of radiotherapy applications.

Radiation-induced perturbation of cell-to-cell signalling and communication.

The investigation of the bystander phenomena (i.e. the induction of damage in cells not directly traversed by radiation) is strictly related to the study of the mechanisms of intercellular communication and of the perturbative effects of radiation. A new possible way to try to solve the bystander puzzle is through a 'systems radiation biology' approach with the total integration of experimental and theoretical activities. In particular, this contribution will focus on: (1) 'ad hoc' experiments designed to quantify key parameters involved in intercellular signalling (focusing, as a pilot study, on release, decay and internalization of interleukine-6 molecules, their modulation by radiation, and possible differences between in vivo/in vitro behaviour); (2) the implementation and the development of two different modelling approaches: a stochastic model (based on a Monte Carlo code) that takes account of the local mechanisms of release and internalization of signalling molecules (e.g. cytokines) and an analytical model where signal molecules are treated as a population and their temporal behaviour is described by differential equations. This approach provided instruments to investigate the complex phenomena of signal transmission and the role of cell communication to guarantee (maintain) the robustness of the in vitro experimental systems against the effects of perturbations.

Some considerations for the study of TGFbeta in medium of irradiated T98G cells: activation, release and consumption.

BACKGROUND: Transforming growth factor ß1 (TGFß1) has been proposed as a candidate for the transmission of radiation-induced bystander signals. AIM: To assess the influence that the presence of latent TGFß in the medium may have on the modulation of TGFß1 release and on its receptor (TGFßR2) expression after irradiation of glioblastoma cells or after treatment with medium collected from γ-irradiated cells. MATERIALS AND METHODS: T98G cells cultured with a complete medium or a serum-free medium were irradiated with 0.25 and 1 Gy and the concentration of total TGFß1 was measured. RESULTS AND CONCLUSIONS: Irradiation of cells growing with a complete medium (i.e. a medium containing latent TGFß1, LTGFß1) caused a consistent dose-dependent decrease of the TGFß1 available in the medium. When LTGFß1 was not available in the medium (i.e. a medium without serum supplement), the levels of TGFß1 increased significantly. Changes in the pattern of expression of TGFßR2 were evident only when a serum-free medium was used.

IL-8 and IL-6 bystander signalling in human glioblastoma cells exposed to gamma radiation.

BACKGROUND: Exposure of cells to ionising radiation causes the release of several factors, such as cytokines, which are likely to be involved in some biological effects occurring in the irradiated cells and in the neighbouring non-irradiated cells (i.e. bystander effect). MATERIALS AND METHODS: The release of interleukin (IL)-6 and IL-8 in the culture medium of irradiated human glioblastoma cells was investigated using an ELISA technique. Immunocytochemistry was used to investigate the expression of corresponding cell membrane receptors in irradiated cells and in cells cultured with medium collected from irradiated cells. RESULTS: The exposure to radiation determined an increase of IL-6 concentration which was dose dependent at 20 hours, whereas IL-8 release was lower than control shortly after irradiation but increased with time, in particular at the dose of 0.5. CONCLUSION: Our data suggest that these cytokines are differently modulated by radiation and are likely to play a role in the transmission of radiation-induced response, probably orchestrating the inflammatory microenvironment of the tumour.

A Monte Carlo study of the radiation quality dependence of DNA fragmentation spectra.

We simulated the irradiation of human fibroblasts with gamma rays, protons and helium, carbon and iron ions at a fixed dose of 5 Gy. The simulations were performed with the biophysical Monte Carlo code PARTRAC. From the output of the code, containing in particular the genomic positions of the radiation-induced DNA double-strand breaks (DSBs), we obtained the DNA fragmentation spectra. Very small fragments, in particular those related to "complex lesions" (few tens of base pairs), are probably very important for the late cellular consequences, but their detection is not possible with the common experimental techniques. We paid special attention to the differences among the various ions in the production of these very small fragments; in particular, we compared the fragmentation spectra for ions of the same specific energy and for ions of the same LET (linear energy transfer). As found previously for iron ions, we found that the RBE (relative biological effectiveness) for DSB production was considerably higher than 1 for all high-LET radiations considered. This is at variance with the results obtainable from experimental data, and it is due to the ability to count the contribution of small fragments. It should be noted that for a given LET this RBE decreases with increasing ion charge, due mainly to the increasing mean energy of secondary electrons. A precise quantification of the DNA initial damage can be of great importance for both radiation protection, particularly in open-space long-term manned missions, and hadrontherapy.

In-vitro effects of the tyrosine kinase inhibitor imatinib on glioblastoma cell proliferation.

Glioblastoma (GBL) is the most malignant brain tumour in adults, causing the death of most patients within 9-12 months of diagnosis. Treatment is based on a combination of surgery, radiation therapy, and chemotherapy. With these treatment modalities, however, responses are extremely poor, so identification of novel treatment strategies is highly warranted. Platelet-derived growth factors (PDGF) and their receptors are commonly coexpressed in GBL, suggesting that stimulation of autocrine PDGF receptors may contribute to their growth. Interest in these receptors as drug target for glioblastoma treatment has increased with the clinical availability of the PDGFR kinase inhibitor antagonist imatinib mesylate (STI571). In this study, T98G and A172 human GBL cell lines were analysed for their sensitivity to treatment with imatinib. In particular, we focussed our attention on analysis of DNA distribution by flow cytometry at different times of incubation with different imatinib concentrations (1-30 microM: ). Our results show that imatinib induces growth arrest in T98G and A172 cells in the G(0)/G(1) phase of the cell cycle, at all the concentrations tested, as early as 24 h after treatment. However we have also seen, by means of annexin V staining, that at 20 and 30 microM: concentrations, in concomitance with a significant growth arrest in the G(0)/G(1) phase, there is an increase of apoptotic cells 48 h after treatment, suggesting that imatinib at low concentrations (1-10 microM: ) could act as a cytostatic agent whereas at high concentrations (20, 30 microM: ) it mainly behaves as a cytotoxic agent.

Different underlying neurocognitive deficits in developmental dyslexia: a comparative study.

The aim of this study was to investigate the role of several specific neurocognitive functions in developmental dyslexia (DD). The performances of 60 dyslexic children and 65 age-matched normally reading children were compared on tests of phonological abilities, visual processing, selective and sustained attention, implicit learning, and executive functions. Results documented deficits in dyslexics on both phonological and non-phonological tasks. More stringently, in dyslexic children individual differences in non-phonological abilities accounted for 23.3% of unique variance in word reading and for 19.3% in non-word reading after controlling for age, IQ and phonological skills. These findings are in accordance with the hypothesis that DD is a multifactorial deficit and suggest that neurocognitive developmental dysfunctions in DD may not be limited to the linguistic brain area, but may involve a more multifocal cortical system.

Influence of imatinib mesylate on radiosensitivity of astrocytoma cells.

Imatinib mesylate (STI571), an inhibitor of alpha- and beta-platelet-derived growth factor receptors (PDGFR) and other tyrosine kinases, is a well established treatment for chronic myeloid leukaemia and gastrointestinal stromal tumours. Moreover, it is under investigation for the therapy of several other malignant tumours since protein kinases are frequently mutated or otherwise deregulated in human malignancies and they serve as a target for differentiating between tumour cells and normal tissues. The objective of this study was to determine whether gamma radiation could sensitize astrocytoma cell lines to the effects of imatinib in vitro. For this purpose, T98G and MOG-G-UVW astrocytoma cells were treated with imatinib alone or in combination with gamma radiation. The clonogenic survival assays performed with the combination of imatinib with radiation demonstrated that the drug had an additive antiproliferative effect in both cell lines considered. Imatinib confered greater radiosensitivity on the T98G tumour cells effecting a significant decrease in colony formation compared with radiation alone. These data provide a rationale to further investigate the combination of imatinib with radiation, keeping in mind that this may result in unexpected toxicities that are not observed with either treatment alone.

Immunobiological and experimental aspects of malignant astrocytoma.

Today several findings indicate that a multifactorial strategy is the best strategy for treating cancer. Although radiotherapy, chemotherapy and surgery have been differently applied to treat human gliomas, no substantial improvement in life expectancy has been observed. Starting from 1992, the goal of our studies was to obtain new biological data on malignant astrocytomas to better understand the basic biology of the tumour and these are reviewed here. Immunotherapy may represent an available method in addition to the traditional therapeutic approaches. Starting from 1991, we set up a cellular model of lymphocytes obtained from peripheral blood of healthy patients treated with interleukin-2 (IL-2) in order to study the role of IL-2 in regulating lymphocytes activation. The lymphocytes responding to IL-2 treatment, named lymphokine-activated killer (LAK) cells, have a killer non MHC restricted activity, and are able to kill autologous and allogenic glioma cells. The interaction of LAK cells with various normal and transformed targets indicates that LAK cells recognize surface structures present both on normal and transformed cells. However, only the interaction with transformed cells induces lytic events and LAK cells can act as "surgical weapons" against tumour cells independently from their cell cycle. Much recent effort has focused on identifying the immune escape mechanisms used by glioma cells, in particular the modulation of the human leukocyte antigen (HLA) and antigen processing machinery component expression. Finally, another interesting field of research that will be presented is that of new tumour biomarkers of proliferation and apoptosis, cytokine/chemokine release and cytokine/chemokine receptors.

DNA fragmentation induced in human fibroblasts by 56Fe ions: experimental data and Monte Carlo simulations.

We studied the DNA fragmentation induced in human fibroblasts by iron-ion beams of two different energies: 115 MeV/nucleon and 414 MeV/nucleon. Experimental data were obtained in the fragment size range 1-5700 kbp; Monte Carlo simulations were performed with the PARTRAC code; data analysis was also performed through the Generalized Broken Stick (GBS) model. The comparison between experimental and simulated data for the number of fragments produced in two different size ranges, 1-23 kbp and 23-5700 kbp, gives a satisfactory agreement for both radiation qualities. The Monte Carlo simulations also allow the counting of fragments outside the experimental range: The number of fragments smaller than 1 kbp is large for both beams, although with a strong difference between the two cases. As a consequence, we can compute different RBEs depending on the size range considered for the fragment counting. The PARTRAC evaluation takes into account fragments of all sizes, while the evaluation from the experimental data considers only the fragments in the range of 1-5700 kbp. When the PARTRAC evaluation is restricted to this range, the agreement between experimental and computed RBE values is again good. When fragments smaller than 1 kbp are also considered, the RBE increases considerably, since gamma rays produce a small number of such fragments. The analysis performed with the GBS model proved to be quite sensitive to showing, with a phenomenological single parameter, variations in double-strand break (DSB) correlation.

Proliferation and programmed cell death: role of p53 protein in high and low grade astrocytoma.

p53 is a cell cycle regulator that has been well-recognized as the key molecule that triggers the induction and the control of cell proliferation and apoptosis in a wide variety of tumours, including astrocytoma. Apoptosis and proliferation are two processes intimately coupled, that occur simultaneously in tumour tissue. Previous studies of the correlations between proliferation and apoptotic index with p53 expression in astrocytic tumours have remained inconclusive. The aim of this study was to investigate the correlation of p53 expression with the apoptotic index (AI) and the cell proliferation index (PI) in pilocytic astrocytoma (PA) and glioblastoma multiforme (GBM). A correlation of p53 expression with AI and PI was found in pilocytic astrocytoma but not in glioblastoma, probably because of the mutated p53 phenotype in the latter.

Effectiveness of stereotactic body radiotherapy in the treatment of inoperable early-stage lung cancer.

BACKGROUND: Non-small cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. Stereotactic body irradiation offers a non-invasive treatment modality for patients with early stage NSCLC who are not amenable to surgery or other invasive approaches because of their poor medical condition. PATIENTS AND METHODS: Forty-three inoperable patients with NSCLC were treated with SBRT at our institution. A mean total dose of 30.5 Gy in 1-4 fractions was applied. The median follow-up duration was 14 months (range 6-36 months). RESULTS: The actuarial survival at two years was 53%: two patients died from cancer progression whereas a further 8 patients died from comorbidities. Acute toxicity was practically absent, with 7 (16.3%) patients suffering from grade 1 symptoms and two from (4.6%) grade II effects. At the time of this report, only 1 patient had grade II and 6 patients (13.9%) grade I chronic symptoms. CONCLUSION: Our results compare favourably with recently published studies and confirm that stereotactic radiotherapy has the potential to produce high local control rates with a low risk of lung toxicity in patients not amenable to curative resection. The low grade of side-effects is encouraging for shortening the treatment using a greater dose per fraction.

Exogenous platelet-derived growth factor (PDGF) induces human astrocytoma cell line proliferation.

Platelet-derived growth factor receptors (PDGFR) regulate several processes in normal cells including cellular proliferation, differentiation and migration, and are widely expressed in a variety of malignancies. In astrocytoma, PDGF ligand and receptor are often overexpressed and PDGFR activity deregulation has been linked to pathogenesis. The issue of the functional capacity of PDGFR has only occasionally been addressed in glioma cells by measuring the proliferative response induced by exogenous PDGF. In the present study, PDGFRalpha expression was evaluated in human grade 2 and 4 astrocytoma cell lines and tissue specimens by immunocytochemistry. The receptor responsiveness to exogenous PDGF was determined in astrocytoma cells with an MTT assay. It was found that astrocytoma cells express PDGFRalpha and respond to PDGF mitogenic action in a grade-dependent manner. The receptor was found to be functional since it induced cell proliferation at different ligand concentrations. We can thus conclude that the proliferative response of human astrocytoma cells is related to their malignancy and receptor status before PDGF stimulation, suggesting a role for PDGFRalpha inhibitors as blockers of malignant cell proliferation.

Surface properties and implantation site affect the capsular fibrotic overgrowth.

Transplantation of encapsulated pancreatic islets is a promising approach for the treatment of type 1 diabetes. Large-scale application of this technique, however, is hampered by insufficient biocompatibility of the capsules. In this study, we have evaluated the biocompatibility of a new synthetic material with six different chemical groups on their surface (amino, carboxy-sulfate, carboxylate, hydroxylate, sulfate, and PMMA) used for the fabrication of the microcapsules. Eight Lewis rats were inoculated with a suspension of empty capsules made for each candidate material in the retroperitoneal ileopsoas muscle and renal subcapsular space. Four weeks later kidney and muscle containing the capsules were explanted, paraffin embedded, sectioned and stained with Sirius Red and Masson's Trichrome for histological analysis. The amount of fibrosis was also ultrastructurally evaluated with scanning electron microscopy. The samples were then subjected to digitalized quantitative analysis using specific software to determine the degree of fibrotic overgrowth. The quantification of collagen deposition, calculated in proximity of the microcapsules, was expressed as a percentage of the total area and can be considered a good index for the biocompatibility, an essential prerequisite for functional pancreatic islet transplantation. The results show that subcapsular renal space is the best implantation site and the positive surface charge induces a more intense collagen synthesis.

Association of short-term memory with a variant within DYX1C1 in developmental dyslexia.

A substantial genetic contribution in the etiology of developmental dyslexia (DD) has been well documented with independent groups reporting a susceptibility locus on chromosome 15q. After the identification of the DYX1C1 gene as a potential candidate for DD, several independent association studies reported controversial results. We performed a family-based association study to determine whether the DYX1C1 single nucleotide polymorphisms (SNPs) that have been associated with DD before, that is SNPs '-3GA' and '1249GT', influence a broader phenotypic definition of DD. A significant linkage disequilibrium was observed with 'Single Letter Backward Span' (SLBS) in both single-marker and haplotype analyses. These results provide further support to the association between DD and DYX1C1 and it suggests that the linkage disequilibrium with DYX1C1 is more saliently explained in Italian dyslexics by short-term memory, as measured by 'SLBS', than by the categorical diagnosis of DD or other related phenotypes.

Modelling radiation-induced bystander effect and cellular communication.

In the last 10 years evidence has accumulated on the so-called radiation-induced 'non-targeted effects' and in particular on bystander effects, consisting of damage induction in non-irradiated cells most likely following the release of soluble factors by the irradiated ones. These phenomena were observed for different biological endpoints, both lethal and non-lethal for the cell. Although the underlying mechanisms are largely unknown, it is now widely recognised that two types of cellular communication (i.e. via gap junctions and/or release of molecular messengers into the extracellular environment) play a pivotal role. Furthermore, the effects can be significantly modulated by parameters such as cell type and cell-cycle stage, cell density, time after irradiation etc. Theoretical models and simulation codes can be of help to improve our knowledge of the mechanisms, as well as to investigate the possible role of these effects in determining deviations from the linear relationship between dose and risk which is generally applied in radiation protection. In this paper three models, including an approach under development at the University of Pavia, will be presented in detail. The focus will be on the various adopted assumptions, together with their implications in terms of non-targeted radiobiological damage and, more generally, low-dose radiation risk. Comparisons with experimental data will also be discussed.

Immunohistochemical evaluation of minichromosome maintenance protein 7 in astrocytoma grading.

The minichromosome maintenance (MCM) proteins, which play an important role in eukaryotic DNA replication, represent a group of proteins that are currently under investigation as novel diagnostic tumor markers. Several studies have proved a greater reliability of MCM proteins to stain proliferating cells compared to Ki67 protein, a routinely used proliferation marker in histopathology. In the present study, the expressions of MCM7 and Ki67 were estimated in 66 primary human astrocytomas in relation to tumor grade (Grade I-IV, WHO). MCM7 significantly stained more nuclei compared to Ki67 in all the histopathological grades investigated. In addition, a stronger increase of the MCM7 labelling index, in relation to the tumor aggressiveness, was observed.