Internal limiting membrane peeling in macular hole

Macular hole (MH) is a full-thickness defect in the fovea, the central part of the neurosensory retina. As the fovea is the site responsible for central vision, the main clinical manifestation of MH is central visual field defect and metamorphopsia. Descriptions of MH in the medical literature are available since the 19th century. However, these only aroused renewed interest after Kelly and Wendel had shown that surgery of pars plana vitrectomy (PPV), combined with vitreous cortex detachment and fluid–gas exchange could close MH in a significant proportion of cases, although it was assumed that the retina would be unable to heal. With time, the success rate of MH surgery gradually increased and this surgery is now one of the most successful vitreoretinal surgeries. A recent innovation was the introduction of internal limiting membrane (ILM) peeling, which leads to a reduction in tangential traction and a higher rate of closure, with less recurrence. In the last 10 years, ILM peeling during MH surgery has thus become a routine step and is nowadays performed by most retinal surgeons. With the advent of modern spectral-domain (SD) optic coherence tomography (OCT), however, one can now see abnormal structural changes to the inner retinal surface after surgery with ILM peeling, suggesting that the procedure can cause retinal damage, even though vision improves. Moreover, some clinical studies found adverse functional events that have given rise to concerns regarding the safety of ILM peeling. The purpose of the present PhD thesis was to examine anatomical and functional effects of ILM peeling in MH surgery. We conducted a prospective study in 72 patients with MH, (stages 2, 3 and 4). MH surgery consisted in PPV, ILM peeling, intraocular gas and face down position. Morphologic and functional outcomes were assessed, 3, 6 and 12 months after surgery. The results reveal the presence of microstructural alterations in the different macular layers after MH surgery with ILM peeling, when compared to pre-operative measurements. Thinning of the Ganglion Cell Layer (GCL) and Inner Plexiform Layer (IPL) on both sides of the fovea were the main structural alterations, in particular at the temporal region. In addition, nasal Internal Retinal Layer (IRL) thickening and shortening of papilo-macular distance could also be detected in cases of successful MH surgery with ILM peeling. Multifocal electroretinography (mf ERG) is a noninvasive method that analyses multiple retinal locations around macular area, and was used in this work to provide a topographic map of electrophysiological activity in central retina. Before surgery, mf ERG showed almost undetectable retinal response in foveal and parafoveal areas, in ring 1 and ring 2. After surgery, the improvement in the retinal response density of mf ERG in the same ring seems to be consequent to closure of the MH, with realignment of photoreceptor cells and glial cell activation. Resolution of the central scotoma could be attributed to anatomical repair and, in our study, we found a statistically significant increase in N1 and P1 in ring 1. This increase was dependent on the integrity of Outer Retina Layers (ORL), External Limiting Membrane (ELM) and Elipsoide Zone (EZ). To study the contribution of the peeled ILM to the outcome of MH surgery, the final position of the ILM after surgery was assessed. This analysis reveals that when the ILM flap ended buried into the hole after surgery, no realignment of external layers could be observed. In contrast, when the ILM flap remained over the hole, ELM and EZ were realigned, and vision was improved. In this study, duration of MH and ORL integrity were studied and we concluded that duration of symptoms of MH seem to relate to integrity to these layers. The ultrastructure and behavior of peeled ILM was studied by using light and transmission electron microscopy. We found that when both ILM vitreous sides are in apposition, there are signs of fibrotic activity, producing a basal membrane with collagen microfibrils between the two sides. This suggests that the two ILM surfaces may adhere, flanking the hole and establish a bridge that contributes to better hole closure after MH surgery. Based on the above findings, we conclude that ILM peeling performed in cases of FTMH surgery allows hole closure and vision improvement, even though anatomical differences as seen in OCT, reveals thinning of inner retinal layers and nasal displacement of the closed hole. Multifocal ERG revealed a functional alteration that is dependent on integrity of the ORL. Also, the position of ILM over the hole may have consequences on integrity of ORL and, consequently, BCVA.XIX Sumário A retina é um tecido neuronal transparente composto de várias camadas e que forra os dois terços posteriores do globo ocular. A mácula, responsável pela visão central, visão de cores e de alta resolução, está situada no chamado polo posterior, entre as arcadas vasculares da retina. Tem um diâmetro de cerca de 5,5mm estando o seu centro a 3,5 mm do bordo do disco óptico e 1mm abaixo do centro do disco, em olhos emétropes. A fóvea corresponde ao centro da mácula. Na retina encontramos duas camadas básicas, a mais posterior, camada de epitélio pigmentar e a interna, camada neurossensorial. Esta retina neurossensorial é composta por 9 camadas, sendo do lado vítreo para o lado coroideu: Membrana limitante interna (MLI) Camada de células nervosas (CCN) Camada de Células ganglionares (CCG) Camada plexiforme interna (CPI) Camada nuclear interna (CNI) Camada plexiforme externa (CPE) Camada nuclear externa (núcleo dos fotorreceptores) Membrana limitante externa (MLE) Camada de fotorreceptores (zona elipsoide, ZE) Assim, a retina neurossensorial é composta de 3 camadas de corpos celulares neuronais e duas camadas de sinapses. A camada nuclear externa contém corpos celulares dos cones e bastonetes, a camada nuclear interna contém corpos celulares das células bipolares, horizontais e amácrinas. A camada de células nervosas é constituída por células ganglionares e algumas células amácrinas. Entre estas camadas de células neuronais, existem as camadas plexiformes em que ocorrem contactos sinápticos. Na camada plexiforme externa, ocorrem contactos entre cones, bastonetes e células bipolares e células horizontais. A camada plexiforme interna, permite a comunicação entre células XX bipolares e células ganglionares, assim como informações das células amácrinas e horizontais sobre as células ganglionares. A membrana limitante interna é camada mais interna da retina e faz fronteira com o humor vítreo pelo que forma uma barreira de difusão entre a retina neuronal e humor vítreo. É considerada a membrana basal das células de Müller, formada pelos podócitos destas células, colagénio e proteoglicanos, que permite a adesão da MLI à retina e adesão do vítreo cortical à MLI. A membrana limitante externa forma a barreira para o espaço subretiniano, onde se projectam as porções internas e externas dos fotorreceptores para permitir associação com a camada de epitélio pigmentado atrás e a própria retina neuronal. O Buraco Macular é um defeito retiniano na fóvea, zona central da retina neurossensorial. Sendo a fóvea responsável pela visão central, o buraco macular pode originar metamorfopsia e defeito central nos campos visuais. O diagnóstico de Buraco Macular existe desde o século 19. No entanto, o seu interesse tem sido maior desde que Kelly e Wendell revelaram que era possível a resolução cirúrgica do buraco macular com vitrectomia via pars plana, descolamento posterior do vítreo e trocas fluido/ar. Apesar de se considerar que a retina não tivesse capacidade regenerativa, esta técnica permitia encerrar os Buracos Maculares em grande parte dos doentes. A taxa de sucesso no encerramento do Buraco Maculares foi gradualmente melhorando e, hoje em dia, é considerada a patologia vítreo-retiniana com maior sucesso cirúrgico. Com a introdução de delaminação da MLI, reduziu-se a tracção tangencial o que permitiu uma maior taxa de encerramento do buraco e menos recidivas. Nos últimos 10 anos a delaminação da MLI na cirurgia de buraco macular tornou-se rotina e é praticada pela maioria de cirurgiões vítreo-retinianos. Com o advento da Tomografia de Coerência Óptica (OCT) de domínio espectral (SD), conseguem-se observar alterações estruturais da retina interna com a delaminação, sugerindo possível lesão retiniana, mesmo que se verifique que o buraco encerre e a visão melhore. Por outro lado, a maior ou menor integridade da MLE e ZE observados no OCT após encerramento do buraco, parecem ter relação com a recuperação da função visual. No entanto, alguns estudos revelaram alterações adversas que originaram preocupação sobre a segurança desta manobra. O objectivo da presente tese foi observar efeitos anatómicos e funcionais desta delaminação na cirurgia do buraco macular. Fizemos um estudo prospectivo em 72 doentes com buraco macular de estadio 2, 3 ou 4, submetidos a cirurgia de vitrectomia via pars plana, delaminação da membrana limitante interna, trocas fluído/ar, gaz e decúbito ventral. Os resultados pós-operatórios foram registados aos 3, 6 e 12 meses após a cirurgia. Quanto a alterações anatómicas, os resultados revelaram alterações microestruturais nas diferentes camadas maculares após delaminação da MLI na cirurgia de buraco macular comparativamente aos dados pré-operatórios. Um estreitamento da camada de células ganglionares (CCG) e camada plexiforme interna (CPI), em ambos os lados, nasal e temporal da fóvea, parecem ser as maiores alterações. Mas a diferença de estreitamento das camadas, em cada um dos lados, nasal e temporal, são igualmente importantes, sendo a espessura total nasal maior que a espessura total temporal. Encontrou-se, ainda, um aumento da espessura do sector interno das camadas internas da macula nasal, assim como um encurtamento da distância entre o disco óptico e a mácula, após cirurgia com pelagem da MLI e encerramento do buraco. Assim, o buraco macular encerra modificando a sua posição inicial, aproximando-se do disco óptico e aumentando a espessura nasal da mácula. Utilizou-se o ERG multifocal para estudo de alterações funcionais da mácula antes e depois da pelagem da MLI na cirurgia do buraco macular. Trata-se de um método não invasivo que seleciona múltiplas zonas à volta da área macular, de modo a permitir um mapa topográfico de actividade eletrofisiológica na retina central. Após cirurgia eficaz, passa a haver um buraco encerrado, com ou sem integridade da membrana limitante externa, zona elipsoide e epitélio pigmentado. Neste estudo funcional, o ERG multifocal revelou, antes da cirurgia, uma resposta retiniana indetectável na área foveal e parafoveal nos anéis 1 e 2. Após encerramento do buraco, a melhoria da resposta retiniana nos dois anéis referidos parecem ser consequência do encerramento do buraco com realinhamento dos fotorreceptores. A resolução do escotoma central parece ser devida a reparação anatómica do buraco. No nosso estudo houve um aumento das ondas N1 e P1 no anel 1. Este aumento foi dependente da integridade das camadas externas da mácula, MLE e EZ. Em buracos maculares de dimensão elevada, superior a 400 micras, a MLI é delaminada até ao bordo do BM, reservando uma porção maior que é dobrada sobre si própria e colocada sobre o buraco, permitido o seu encerramento. Comprovámos que o resultado funcional e a integridade dos fotorreceptores dependiam da posição final da porção de MLI sobre o BM. Neste estudo, verificámos que se um fragmento de MLI ficasse enterrada no buraco, havia encerramento do buraco, mas não realinhamento dos fotorreceptores. Se o fragmento de MLI se mantivesse sobre o BM, o BM encerrava e a camadas de fotorreceptores, traduzida pela membrana limitante externa e zona elipsoide, revelavam integridade em grande parte dos casos. Para esta integridade também tinha importância o tempo de evolução do BM. Quanto menor tempo de evolução do BM, melhor a taxa de realinhamento das camadas externas da macula. Sempre que possível, durante a cirurgia macular, depois da delaminação da MLI e de colocada uma porção evertida de MLI sobre o buraco, eram excisados dois outros pedaços de MLI e estes enviados para estudo. A ulta estrutura e o comportamento da membrana limitante interna excisada foram estudadas por microscopia óptica e electrónica. Verificou-se que, em meio rico, e estando as duas faces vítreas da MLI em contacto, havia sinais de actividade fibrótica com produção de membrana basal, o que permitia a aderência destas duas faces de MLI. Sugerimos no nosso estudo que células epiretinianas na MLI pudessem ter capacidade proliferativa, com formação de microfibrilhas entre as duas faces adjacentes de MLI. Este facto poderia explicar a aderência observada entre o folheto de ILM e os bordos do buraco macular, depois da cirurgia, o que contribuiria para o encerramento do BM. Baseados nos resultados encontrados, poderemos concluir que a delaminação de MLI em todos os casos de cirurgia de BM permite o encerramento do buraco e melhoria da visão, apesar de se verificar alterações importante na anatomia, medidas pela tomografia de coerência óptica, antes e depois da cirurgia. As alterações anatómicas mais importantes são diminuição da espessura das camadas internas da mácula, nasal e temporal, um aumento da espessura total da porção nasal da mácula e uma diminuição da espessura temporal. E, ainda, um desvio nasal do BM depois do seu encerramento. O ERG multifocal revela alterações funcionais na mácula depois de cirurgia com pelagem da MLI e, esta alteração, depende da integridade das camadas externas da mácula. A integridade das camadas externas, MLE, ZE e EP determinam a função visual final. Para ser possível esta integridade, a posição da porção de MLI sobre o BM é muito importante, dependendo se esta fica enterrada no meio do buraco ou se fica sobre o buraco. Por fim, na análise por microscopia electrónica da MLI excisada, encontrámos microfibrilhas de colagénio entre as duas faces vítreas da membrana, que poderão contribuir para o mecanismo de encerramento do Buraco macular

Service bundling opportunities for a 3PL in the value network

Thesis (S.M.M.O.T.)--Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program, 2003.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Originally written by two authors for two different degrees: Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program (Mr. Chew); and, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program (Mr. de Graeve). Mr. Chew graduated June 2003; Mr. de Graeve did not graduate until June 2004, and submitted the following thesis with title: Framework for the study of governance in the supply networksIncludes bibliographical references (leaves 96-99).The 3PL industry is currently experiencing rapid growth, high fragmentation and intense competition. In order to survive and stay relevant going forward 3PLs need to re-assess their current position in the value network and develop a clear strategy to position themselves as strategic business partners for the long term. This thesis first explores the supply chain challenges and needs of the major stakeholders in the value network. It then tries to create a roadmap identifying the major opportunities which 3PLs should optimize in order to become true value-added service providers and long term strategic business partners in the value network.by Chee Mun Chew & Denis de Graeve.S.M.M.O.T

The Family Mealtime Study: Parent Socialization and Context During Family Meals

Research on the family mealtime has shown its importance for youths\u27 dietary attitudes and behaviors. Youths who have more frequent family meals often have more healthful dietary behaviors. However, little is known about the context and processes related to how family mealtimes affect youths\u27 dietary behaviors. To address this gap, we examined the context of family mealtimes and parent socialization that occurs during family meals through mealtime observations and interviews. Family mealtimes are valued by parents, and our findings can be useful to Extension professionals in educating parents and families regarding shaping of family mealtimes, feeding strategies, and nutrition

Current-phase relation of the SNS junction in a superconducting loop

We study the current-phase relation of the superconductor/normal/superconductor (SNS) junction imbedded in a superconducting loop. Considering the current conservation and free energy minimum conditions, we obtain the persistent currents of the normal/superconductor (NS) loop. At finite temperature we can explain the experimentally observed highly non-sinusoidal currents which have maxima near the zero external flux.Comment: 7 pages, 3 figures, version to appear in Europhys. Let

Implementación de un agente conversacional mediante Microsoft Bot Framework y Azure Cognitive Services como herramienta de divulgación de la condición de la mujer en el contexto de la igualdad de género

La desigualdad y discriminación de género es un desafío a superar en las sociedades actuales, donde sus poblaciones, que aun contando con un acceso privilegiado a la información, a menudo sentencian este problema como inexistente o se niegan en reiteradas ocasiones a contrastar los datos a los que acceden para formar una opinión razonada. Con este proyecto pretende abordar la desinformación al respecto de la desigualdad y discriminación de género utilizando fuentes veraces y públicas para la difusión de información actualizada sobre esta problemática. Para lograr este objetivo, se hará uso de tecnologías de vanguardia como Microsoft Bot Framework y soluciones de inteligencia artficial como Microsoft LUIS. Estas herramientas permitirán generar experiencias de conversación naturales, facilitando discusiones relevantes sobre la temática. También se utilizarán herramientas que permitan el tratamiento y visualización de datos estadísticos, potenciando la presentación de los datos así como su asimilación. El proyecto se desarrolla siguiendo el marco de trabajo ágil Scrum, iniciado en la etapa de planificación del proyecto, seguido por el análisis del sistema, su diseño, implementación y realización de pruebas.Inequality and discrimination based on gender are challenges that current societies must overcome. Despite having privileged access to information, populations often dismiss this problem as non-existent or repeatedly refuse to contrast the data they have access to in order to form a reasoned opinion. This project aims to tackle the pervasive issue of misinformation surrounding gender inequality and discrimination by harnessing reliable and publicly available sources to disseminate accurate and up-to-date information to the public. To achieve this objective, the project will leverage cutting-edge technologies such as Microsoft Bot Framework and artificial intelligence solutions as Microsoft LUIS. These tools will enable the generation of natural conversation experiences, facilitating meaningful discussions on the topic. Additionally, the project will employ data processing and statistical visualization tools, empowering the presentation of relevant data. The project will adhere to the agile Scrum framework, starting with the project planning, followed by system analysis, design considerations, implementation and testing procedures.Departamento de Informática (Arquitectura y Tecnología de Computadores, Ciencias de la Computación e Inteligencia Artificial, Lenguajes y Sistemas Informáticos)Grado en Ingeniería Informátic

Organización Empresarial II: la responsabilidad social corporativa, recursos humanos y marca empleador: un estudio de Inditex”

Un comportamiento ético y sostenible por parte de las empresas se ha convertido en una exigencia global por parte de la sociedad. En este contexto, la Responsabilidad Social Corporativa, o RSC, es un elemento clave que, integrada en las organizaciones, permitirá influir en la creación de valor de la empresa en diversos ámbitos, entre ellos el de la atracción y retención de talento humano. Este trabajo busca conceptualizar la RSC y analizar las formas que las empresas tienen a su disposición para integrar la RSC en sus actividades, enfocándonos de manera especial en su influencia sobre los recursos humanos, o RRHH. Al mismo tiempo, procuramos entender la conexión entre la RSC y su influencia sobre un factor importante para los RRHH; la Marca Empleador, o ME, abordando su concepto, proceso de creación y beneficios. Buscando aportar un tratamiento empírico, se tratará en el último punto, de manera breve y descriptiva, el análisis de la estrategia e iniciativas en RSC por parte del Grupo Inditex en sus distintas áreas, y su influencia sobre su MEIt is known that society has been increasingly demanding a more ethical and sustainable approach from companies. In this context, Corporate Social Responsability, also known as CSR, is a key element that will allow organizations to generate added value in different fields of its activity, among one of them, attracting and retaining human talent. This study seeks to understand the concept of CSR and clarifying the ways in which companies can integrate CSR into its activities, as well as focusing on CSR’ influence over its human resources. Simultaneously, we seek to understand CSR influence over the Employer Branding, addressing its concept, creation process and the benefits associated to it. As we also wish to provide a empiral contribution, the final part of this study will tackle on the descriptive analysis of Group Inditex’ strategies and initiatives on CSR throughout various functional areas and its influence over its Employer Branding.Departamento de Organización de Empresas y Comercialización e Investigación de MercadosGrado en Administración y Dirección de Empresa

Pilot study assessing the influence of skin type on the heart rate measurements obtained by photoplethysmography with the Apple Watch

Photoplethysmographic imaging (PPG) is currently used to measure heart rate (HR) and the accuracy of PPG can be influenced by pigmentation of the skin; however, the effects of skin color-related artifacts on PPG during exercise remain unclear. This study aimed to assess the agreement between the Apple Watch photoplethysmography sensor and a criterion, for measuring heart rate across a range of intensities during exercise and to determine the influence of skin type on the accuracy of the measure. Forty-five males (20–43 y) completed the Fitzpatrick Skin Scale and were classified into three different skin type groups: a) types II (n = 15), III (n = 15) and IV (n = 15). Participants performed a graded incremental cycle-ergometer test while simultaneously wearing the Apple Watch and a Polar monitor as a criterion measure. Data from both devices were collected in 5-s epochs. Correlations between devices were very good (0.96–0.99 [95%CI: 0.94 to 0.99]). Significant differences were observed between skin types II and III when the intensity of the exercise was increased, albeit with trivial to small effect sizes (ES: 0.05 to 0.28). All significant differences corresponded t

Bose glass and Mott glass of quasiparticles in a doped quantum magnet

The low-temperature states of bosonic fluids exhibit fundamental quantum effects at the macroscopic scale: the best-known examples are Bose-Einstein condensation (BEC) and superfluidity, which have been tested experimentally in a variety of different systems. When bosons are interacting, disorder can destroy condensation leading to a so-called Bose glass. This phase has been very elusive to experiments due to the absence of any broken symmetry and of a finite energy gap in the spectrum. Here we report the observation of a Bose glass of field-induced magnetic quasiparticles in a doped quantum magnet (Br-doped dichloro-tetrakis-thiourea-Nickel, DTN). The physics of DTN in a magnetic field is equivalent to that of a lattice gas of bosons in the grand-canonical ensemble; Br-doping introduces disorder in the hoppings and interaction strengths, leading to localization of the bosons into a Bose glass down to zero field, where it acquires the nature of an incompressible Mott glass. The transition from the Bose glass (corresponding to a gapless spin liquid) to the BEC (corresponding to a magnetically ordered phase) is marked by a novel, universal exponent governing the scaling on the critical temperature with the applied field, in excellent agreement with theoretical predictions. Our study represents the first, quantitative account of the universal features of disordered bosons in the grand-canonical ensemble.Comment: 13+6 pages, 5+6 figures; v2: Fig. 5 update

2023 WSES guidelines for the prevention, detection, and management of iatrogenic urinary tract injuries (IUTIs) during emergency digestive surgery

Bladder injury; Urinary injury management; Urinary injury preventionLesió de la bufeta; Maneig de lesions urinàries; Prevenció de lesions urinàriesLesión de la vejiga; Manejo de lesiones urinarias; Prevención de lesiones urinariasIatrogenic urinary tract injury (IUTI) is a severe complication of emergency digestive surgery. It can lead to increased postoperative morbidity and mortality and have a long-term impact on the quality of life. The reported incidence of IUTIs varies greatly among the studies, ranging from 0.3 to 1.5%. Given the high volume of emergency digestive surgery performed worldwide, there is a need for well-defined and effective strategies to prevent and manage IUTIs. Currently, there is a lack of consensus regarding the prevention, detection, and management of IUTIs in the emergency setting. The present guidelines, promoted by the World Society of Emergency Surgery (WSES), were developed following a systematic review of the literature and an international expert panel discussion. The primary aim of these WSES guidelines is to provide evidence-based recommendations to support clinicians and surgeons in the prevention, detection, and management of IUTIs during emergency digestive surgery. The following key aspects were considered: (1) effectiveness of preventive interventions for IUTIs during emergency digestive surgery; (2) intra-operative detection of IUTIs and appropriate management strategies; (3) postoperative detection of IUTIs and appropriate management strategies and timing; and (4) effectiveness of antibiotic therapy (including type and duration) in case of IUTIs

Synthesis and characterization of atomically-thin graphite films on a silicon carbide substrate

This paper reports the synthesis and detailed characterization of graphite thin films produced by thermal decomposition of the (0001) face of a 6H-SiC wafer, demonstrating the successful growth of single crystalline films down to approximately one graphene layer. The growth and characterization were carried out in ultrahigh vacuum (UHV) conditions. The growth process and sample quality were monitored by low-energy electron diffraction, and the thickness of the sample was determined by core level x-ray photoelectron spectroscopy. High-resolution angle-resolved photoemission spectroscopy shows constant energy map patterns, which are very sharp and fully momentum-resolved, but nonetheless not resolution limited. We discuss the implications of this observation in connection with scanning electron microscopy data, as well as with previous studies