new insights into the development and progression of geographic atrophy after full thickness autologous choroidal graft

n/

A polymer-based interface restores light sensitivity in blind rats

Progressive degeneration of photoreceptors is one of the major causes of adult blindness in “industrialized” countries; as an example, Retinitis pigmentosa defines a set of monogenic hereditary retinal diseases, with a prevalence of 1:4000 worldwide, caused by single mutations in over 50 genes. Moreover, it is thought that a significant number of implicated genes still await identification (Hartong et al., 2006;Wright et al., 2010;Daiger et al., 2013). In the past 20 years, several treatments have been attempted to treat Retinitis pigmentosa as well as many other retinal genetic diseases, including: drug therapy ( Leveillard and Sahel, 2010), gene therapy (Smith et al., 2012), stem/progenitor cells engrafting (Pearson et al., 2012), optogenetic manipulation (Busskamp et al., 2010), and implantation of prostheses (Weiland et al., 2011;Zrenner et al., 2011). However, despite the enormous efforts and advances in the clinical treatment of eye diseases and some encouraging results in animal models, there is currently no effective cure for the majority of genetic retinal diseases affecting photoreceptors including Retinitis pigmentosa. Sight restoration represents one of the new frontiers for prosthetic devices enabling the electrical stimulation of neurons. In particular, diseases that affect the retinal pigment epithelium and photoreceptors but preserve the inner retinal layers are preferential targets for the implantation of visual prostheses. In our work, we exploited the use of conjugated polymers to generate an organic photovoltaic retinal prosthesis. Our research indicates that organic materials, in particular photovoltaic semiconducting polymers, are suitable for the generation of a fully organic retinal prosthesis, to restore light sensitivity in blindness caused by photoreceptor degeneration. We discovered that primary neurons can be grown onto a semiconductor polymer layer, without affecting the optoelectronic properties of the photovoltaic material (Antognazza et al., 2009) or the physiological properties of the neuronal network over a long period of time. Moreover, we found that a light pulse is able to depolarize neurons and induce them to fire action potentials (Ghezzi et al., 2011). The spatial resolution of the stimulation paradigm was demonstrated to be in the order of the cell body, in spite of the continuous layer of polymer, indicating that the stimulation is strictly confined to the illuminated area. This result encouraged us to test the efficacy of photovoltaic polymers in stimulating retinas explanted from albino rats with reproducibly light-induced degeneration of the photoreceptor layer. To this aim, acutely dissected retinas were placed on the organic polymer in a sub-retinal configuration (i.e., external layers in contact with the polymer). Light stimulation of the degenerate retina was observed by monitoring multi-unit activity and field potentials with an extracellular electrode positioned in the retinal ganglion cell layer. Multi-unit activity recordings showed that a light stimulus 16-fold lower than the safe limit for pulsed illumination elicited intense spiking activity in degenerate retinas placed on polymer-coated substrates to levels indistinguishable from those recorded in control retinas. Moreover, to evaluate the efficiency of the interface, a dose-response analysis of spiking activity versus light intensity were performed in degenerate retinas. Spiking activity was observed in degenerate retinas over the polymer with a response threshold below 0.3 μW/mm2, a linear increase in a range corresponding to daylight irradiance, and a response saturation above 100 μW/mm2 (considered the safe limit for chronic illumination). A 4-fold increase in the amplitude of the light response at saturation and a significant left shift of the dose-response curves were obtained in retinas placed over the polymer-coated interface respect to degenerate retinas on glass substrates. Our finding indicates that the interface could mimic functional photoreceptors in activating the processing of the inner retina and is able to rescue normal light sensitivity (Ghezzi et al., 2013). Following these promising results, we implanted the prosthesis in the eye of rats (Royal College of Surgeons) bearing photoreceptor degeneration due to mutation in the MERTK gene (D'Cruz et al., 2000). These rats are a recognized animal model of human Retinitis pigmentosa. Preliminary experiments performed in a first cohort of animals show that the retina remains well attached over the entire region of the sub- retinal implant without inflammation or fibrosis. Moreover, the ability of the organic prosthesis to restore light sensitivity was first tested by monitoring the pupillary reflex. Pupil constriction in the implanted blind rat was similar to the response of the non-dystrophic animal and significantly higher than the non-implanted blind animal. Finally, visually evoked field potentials were detected in the visual cortex of implanted blind rats, whereas they were undetectable in the non-implanted blind animals. These results open the possibility of developing a new generation of fully organic prosthetic devices for sub-retinal implantation

The p-ERG spatial acuity in the biomedical pig under physiological conditions

Pigs are becoming an important pre-clinical animal species for translational ophthalmology, due to similarities with humans in anatomical and physiological patterns. Different models of eye disorders have been proposed, and they are good candidates to assess biocompatibility/functionality of retinal prostheses. Electroretinography is a common tool allowing to gain information on retinal function, with several types of electroretinogram (ERG) been implemented including full field (ff-ERG), multifocal (mf-ERG) and pattern (p-ERG). p-ERG represents a valuable tool to monitor Retinal Ganglion Cells (RGCs) activity and can be used to calculate p-ERG spatial acuity. Unfortunately, scarce methodological data are available regarding recording/interpretation of p-ERG and retinal acuity in biomedical pigs yet enhancing knowledge regarding pig vision physiology will allow for more refined and responsible use of such species. Aim of this study was to record p-ERG in juvenile pigs to functionally assess visual acuity. Six female hybrid pigs underwent two p-ERG recording sessions at 16 and 19 weeks of age. Photopic ff-ERG were also recorded; optical coherence tomography (OCT) and histology were used to confirm retinal integrity. ff-ERG signals were repeatable within/across sessions. All p-ERG traces consistently displayed characterizing peaks, and the progressive decrease of amplitude in response to the increment of spatial frequency revealed the reliability of the method. Mean p-ERG spatial acuities were 5.7 +/- 0.14 (16 weeks) and 6.2 +/- 0.15 cpd (19 weeks). Overall, the p-ERG recordings described in the present work seem reliable and repeatable, and may represent an important tool when it comes to vision assessment in pigs

Biocompatibility of a Conjugated Polymer Retinal Prosthesis in the Domestic Pig

The progressive degeneration of retinal photoreceptors is one of the most significant causes of blindness in humans. Conjugated polymers represent an attractive solution to the field of retinal prostheses, and a multi-layer fully organic prosthesis implanted subretinally in dystrophic Royal College of Surgeons (RCS) rats was able to rescue visual functions. As a step toward human translation, we report here the fabrication and in vivo testing of a similar device engineered to adapt to the human-like size of the eye of the domestic pig, an excellent animal paradigm to test therapeutic strategies for photoreceptors degeneration. The active conjugated polymers were layered onto two distinct passive substrates, namely electro-spun silk fibroin (ESF) and polyethylene terephthalate (PET). Naive pigs were implanted subretinally with the active device in one eye, while the contralateral eye was sham implanted with substrate only. Retinal morphology and functionality were assessed before and after surgery by means of in vivo optical coherence tomography and full-field electroretinogram (ff-ERG) analysis. After the sacrifice, the retina morphology and inflammatory markers were analyzed by immunohistochemistry of the excised retinas. Surprisingly, ESF-based prostheses caused a proliferative vitreoretinopathy with disappearance of the ff-ERG b-wave in the implanted eyes. In contrast, PET-based active devices did not evoke significant inflammatory responses. As expected, the subretinal implantation of both PET only and the PET-based prosthesis locally decreased the thickness of the outer nuclear layer due to local photoreceptor loss. However, while the implantation of the PET only substrate decreased the ff-ERG b-wave amplitude with respect to the pre-implant ERG, the eyes implanted with the active device fully preserved the ERG responses, indicating an active compensation of the surgery-induced photoreceptor loss. Our findings highlight the possibility of developing a new generation of conjugated polymer/PET-based prosthetic devices that are highly biocompatible and potentially suitable for subretinal implantation in patients suffering from degenerative blindnes

Organic electronics allows the photo-electric excitation of neuronal activity in primary neuronal cultures and acute retinal explants

Interfacing organic electronics and biology offers new possibilities in biotechnology, due to the unique properties exhibited by organic conducting polymers (e.g. biological affinity, mechanical flexibility, ease of functionalization and cost effectiveness). Organic conducting polymers have been exploited as materials for cellular interfaces in several fashions as: (i) passive electrode coatings or culturing substrates, (ii) organic biosensors or (iii) actuators for neurotransmitter release and electrodes for controlled cell seeding, growth and activity detection. Very recently, an organic photovoltaic donor-acceptor blend has been exploited for neuron stimulation by a photo-electric process. With respect to previous examples with inorganic semiconductors, this system has several advantages including flexibility, no power requirement and biocompatibility. Here, we report the novel use of a single component semiconductor organic polymer for the direct control of neuronal activity. This interface, that is more efficient than the classical bulk hetero-junction interface, has the remarkable capability to evoke neuronal firing in response to illumination. We demonstrate that the polymer layer has the ability to induce action potential firing up to 20 Hz in cultured hippocampal neurons. Moreover, this interface has been exploited to restore visual response in retinal explants obtained from animal models of retinal degeneration (light-blinded albino SD rats). By recording local field potentials in the RGC layer, we demonstrated the ability of the organic conductive polymer to mimic the function of photoreceptors and induce retinal activation of retinal ganglion cells after light illumination. These results paved the way to the development of a new and disruptive technology for interfacing artificial devices with neuronal networks, with applications in neuroprosthesis and brain machine interface research

Survival of hereditary non-polyposis colorectal cancer patients compared with sporadic colorectal cancer patients

<p>Abstract</p> <p>Background</p> <p>Patients with hereditary non-poliposys colorectal cancer (HNPCC) have better prognosis than sporadic colorectal cancer (CRC). Aim of our retrospective study was to compare the overall survival between sporadic CRC and HNPCC patients.</p> <p>Methods</p> <p>We analyzed a cohort of 40 (25 males and 15 females) HNPCC cases with a hospital consecutive series of 573 (312 males and 261 females) sporadic CRC observed during the period 1970–1993. In 15 HNPCC patients we performed mutational analysis for microsatellite instability. Survival rates were calculated by Kaplan-Meier method and compared with log rank test.</p> <p>Results</p> <p>The median age at diagnosis of the primary CRC was 46.8 years in the HNPCC series versus 61 years in sporadic CRC group. In HNPCC group 85% had a right cancer location, vs. 57% in the sporadic cancer group. In the sporadic cancer group 61.6% were early-stages cancer (Dukes' A and B) vs. 70% in the HNPCC group (p = ns). The crude 5-years cumulative survival after the primary CRC was 94.2% in HNPCC patients vs. 75.3% in sporadic cancer patients (p < 0.0001).</p> <p>Conclusion</p> <p>Our results show that overall survival of colorectal cancer in patients with HNPCC is better than sporadic CRC patients. The different outcome probably relates to the specific tumorigenesis involving DNA mismatch repair dysfunction.</p

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde