42 research outputs found
Field performance of four vibrating-wire piezometer installation methods
Vibrating wire piezometers provide a number of advantages over the traditional hydraulic piezometer design. There are many methods and configurations for installing vibrating-wire piezometers, with the most common being: single piezometers in sand packs (SP), multilevel piezometers in sand packs (MLSP), and fully-grouted multilevel piezometers using either bentonite (FGB) or cement-bentonite grout (FGCB). This study assesses the performance of these four different installation methods for vibrating wire piezometers at a field site possessing complex stratigraphy, including glacial and marine sediments. Pore pressure data recorded between December 2017 and July 2019 were analyzed to accomplish this objective. Data indicate that SP, MLSP, and FGB piezometers performed well. This determination is based on the fact that piezometers installed at the same depth with these arrangements recorded similar pressure variations that were coherent with the hydrogeological setting. Of the two fully-grouted installations using cement-bentonite grout, one installation failed completely due to a hydraulic short circuit, caused either by shrinkage of the grout or flow occurring along the wires of the embedded instruments. While the FGB-type piezometers used in this study worked correctly, the lack of standard methods concerning both the construction of fully-grouted piezometers is concerning. Furthermore, the lack of a standard method for mixing cement-bentonite grout likely contributed to the failure of the FGCB installations. Thus, due to the lack of guidance for both construction and grout preparation, the use of a bentonite grout removes a degree of uncertainty when fully-grouted installation techniques are used
Parcours-travail et cancers professionnels. Recherche-action en Seine Saint Denis (France)
Dans le domaine des cancers d’origine professionnelle, la toxicologie et l’épidémiologie ont apporté depuis longtemps des connaissances permettant d’identifier des relations causales ou des corrélations statistiques entre des substances toxiques et certains cancers. Mais la réalité sociale du travail dans laquelle s’inscrit l’exposition à des cancérogènes professionnels reste inconnue. La démarche de recherche-action pluridisciplinaire qui concerne la surveillance des cancers professionnels en Seine Saint Denis vise à améliorer la connaissance, la reconnaissance et la prévention des cancers d’origine professionnelle dans ce département. Une phase exploratoire réalisée en 2001 dans deux services du centre hospitalier universitaire Avicenne de Bobigny a permis la mise au point d’outils méthodologiques pour cette démarche. L’objectif est de construire une connaissance qualitative des expositions professionnelles à des cancérogènes à partir de la reconstitution des parcours-travail de patients atteints de cancer résidant en Seine Saint Denis.Nous présentons dans cet article la problématique de cette recherche et ses premiers résultats. L’élaboration d’une typologie des parcours-travail de ces patients vise à inscrire l’exposition à des cancérogènes professionnels en référence à l’histoire combinée de l’emploi, de la qualification et de l’activité de travail de ces patients. Le classement des malades de l’étude selon des types de parcours différents permet de dégager une différenciation des histoires d’exposition aux cancérogènes. L’approche par la typologie des parcours-travail permet de surmonter la difficulté d’analyse des expositions cumulées tout au long de la vie professionnelle et de qualifier ces expositions en référence aux objectifs de prévention et de réparation. Il s’agit d’inscrire ces expositions dans un contexte et une histoire individuels et collectifs dans l’espace et dans le temps et d’analyser les conditions de la reconnaissance en maladie professionnelle.In the field of occupational cancer, toxicology and epidemiology have produced a substantial amount of data that have been used to identify the causal relationship and statistical correlation between toxic substances and some types of cancer. However, little information is available on the social reality of work and occupational exposure to carcinogenic agents. A multidisciplinary and proactive scientific study, based on interviews with incident cases, was undertaken in a highly industrialized suburb of Paris. The preliminary study, carried out in the Avicenne hospital (attached to the University of Paris13, Bobigny), allowed us to build methodological tools. Our goal was to collect qualitative data on occupational exposure to carcinogenic agents in the job histories of new patients living in Seine Saint Denis.In this paper, we present out theoretical and methodological approach, along with some results. Exposure to carcinogens was very common in our study group. We identified different types of job histories involving a combination of blue-collar work and occupational exposure to carcinogens. It was then possible to differentiate between cases due to past occupational exposure to carcinogenic agents and those involving workers who are still exposed in their current positions. Where exposure occurs, there is clearly an urgent need for preventive strategies to avoid future cases of cancer. Through the study, we were able to register cumulated and multiple exposure throughout a worker’s job history and to qualify that exposure. The job history study is not necessarily the only way of identifying whether or not patients have been exposed to carcinogenic agents, but it is a way of developing two other kinds of knowledge, namely how the exposure histories fit into an individual and collective history, both spatially and temporally, and how to recognize and compensate for occupational disease procedures - in other words, to see how the compensation system rules are applied and how they can be changed to suit the specific situation of occupational cancer victims.En el ámbito de los cánceres de origen profesional, la toxicología y la epidemiología han proporcionado, desde hace mucho tiempo, conocimientos que permiten identificar las relaciones causales o las correlaciones estadísticas entre las sustancias tóxicas y ciertos cánceres. Pero la realidad social del trabajo en la cual se desarrolla la exposición a carcinógenos profesionales permanece desconocida. El enfoque de investigación proactiva multidisciplinaria a propósito del seguimiento de los cánceres profesionales en Seine Saint Denis tiene por objeto de mejorar el conocimiento, el reconocimiento y la prevención de los cánceres de origen profesional en este distrito de las afueras de París. Una fase exploratoria realizada en 2001 en dos servicios del centro hospitalario universitario Avicenne de Bobigny ha permitido la elaboración de instrumentos metodológicos para este enfoque. El objetivo es construir un conocimiento cualitativo de las exposiciones profesionales a carcinógenos a partir de la reconstitución de los recorridos laborales de pacientes viviendo en Seine Saint Denis que padecen de cáncer.En este artículo, presentamos la problemática de esta investigación y sus primeros resultados. La elaboración de una tipología de los recorridos laborales de estos pacientes tiene por objetivo subrayar la exposición a carcinógenos profesionales en referencia a la historia combinada de su empleo, su calificación y de su actividad de trabajo. La clasificación de los enfermos según los diferentes recorridos permite destacar una diferenciación de las historias de exposición a carcinógenos. El enfoque por tipología de los recorridos laborales permite superar la dificuldad de análisis de las exposiciones cumuladas a lo largo de la vida profesional y de calificar estas exposiciones en relación con los objetivos de prevención y de reparación. Se trata de clasificar estas exposiciones en un contexto y una historia individuales y colectivos en el espacio y en el tiempo y analizar las condiciones de su reconocimiento como enfermedad profesional
Current Understanding of the Anatomy, Physiology, and Magnetic Resonance Imaging of Neurofluids: Update From the 2022 "ISMRM Imaging Neurofluids Study group" Workshop in Rome
Neurofluids is a term introduced to define all fluids in the brain and spine such as blood, cerebrospinal fluid, and interstitial fluid. Neuroscientists in the past millennium have steadily identified the several different fluid environments in the brain and spine that interact in a synchronized harmonious manner to assure a healthy microenvironment required for optimal neuroglial function. Neuroanatomists and biochemists have provided an incredible wealth of evidence revealing the anatomy of perivascular spaces, meninges and glia and their role in drainage of neuronal waste products. Human studies have been limited due to the restricted availability of noninvasive imaging modalities that can provide a high spatiotemporal depiction of the brain neurofluids. Therefore, animal studies have been key in advancing our knowledge of the temporal and spatial dynamics of fluids, for example, by injecting tracers with different molecular weights. Such studies have sparked interest to identify possible disruptions to neurofluids dynamics in human diseases such as small vessel disease, cerebral amyloid angiopathy, and dementia. However, key differences between rodent and human physiology should be considered when extrapolating these findings to understand the human brain. An increasing armamentarium of noninvasive MRI techniques is being built to identify markers of altered drainage pathways. During the three-day workshop organized by the International Society of Magnetic Resonance in Medicine that was held in Rome in September 2022, several of these concepts were discussed by a distinguished international faculty to lay the basis of what is known and where we still lack evidence. We envision that in the next decade, MRI will allow imaging of the physiology of neurofluid dynamics and drainage pathways in the human brain to identify true pathological processes underlying disease and to discover new avenues for early diagnoses and treatments including drug delivery. Evidence level: 1. Technical Efficacy: Stage 3
Current Understanding of the Anatomy, Physiology, and Magnetic Resonance Imaging of Neurofluids: Update From the 2022 “<scp>ISMRM</scp> Imaging Neurofluids Study group” Workshop in Rome
Neurofluids is a term introduced to define all fluids in the brain and spine such as blood, cerebrospinal fluid, and interstitial fluid. Neuroscientists in the past millennium have steadily identified the several different fluid environments in the brain and spine that interact in a synchronized harmonious manner to assure a healthy microenvironment required for optimal neuroglial function. Neuroanatomists and biochemists have provided an incredible wealth of evidence revealing the anatomy of perivascular spaces, meninges and glia and their role in drainage of neuronal waste products. Human studies have been limited due to the restricted availability of noninvasive imaging modalities that can provide a high spatiotemporal depiction of the brain neurofluids. Therefore, animal studies have been key in advancing our knowledge of the temporal and spatial dynamics of fluids, for example, by injecting tracers with different molecular weights. Such studies have sparked interest to identify possible disruptions to neurofluids dynamics in human diseases such as small vessel disease, cerebral amyloid angiopathy, and dementia. However, key differences between rodent and human physiology should be considered when extrapolating these findings to understand the human brain. An increasing armamentarium of noninvasive MRI techniques is being built to identify markers of altered drainage pathways. During the three‐day workshop organized by the International Society of Magnetic Resonance in Medicine that was held in Rome in September 2022, several of these concepts were discussed by a distinguished international faculty to lay the basis of what is known and where we still lack evidence. We envision that in the next decade, MRI will allow imaging of the physiology of neurofluid dynamics and drainage pathways in the human brain to identify true pathological processes underlying disease and to discover new avenues for early diagnoses and treatments including drug delivery.Evidence level: 1Technical Efficacy: Stage
Recommended from our members
Brain multiplexes reveal morphological connectional biomarkers fingerprinting late brain dementia states
Accurate diagnosis of mild cognitive impairment (MCI) before conversion to Alzheimer’s disease (AD) is invaluable for patient treatment. Many works showed that MCI and AD affect functional and structural connections between brain regions as well as the shape of cortical regions. However, ‘shape connections’ between brain regions are rarely investigated -e.g., how morphological attributes such as cortical thickness and sulcal depth of a specific brain region change in relation to morphological attributes in other regions. To fill this gap, we unprecedentedly design morphological brain multiplexes for late MCI/AD classification. Specifically, we use structural T1-w MRI to define morphological brain networks, each quantifying similarity in morphology between different cortical regions for a specific cortical attribute. Then, we define a brain multiplex where each intra-layer represents the morphological connectivity network of a specific cortical attribute, and each inter-layer encodes the similarity between two consecutive intra-layers. A significant performance gain is achieved when using the multiplex architecture in comparison to other conventional network analysis architectures. We also leverage this architecture to discover morphological connectional biomarkers fingerprinting the difference between late MCI and AD stages, which included the right entorhinal cortex and right caudal middle frontal gyrus
Recommended from our members
Multimodal and Multiscale Deep Neural Networks for the Early Diagnosis of Alzheimer’s Disease using structural MR and FDG-PET images
Alzheimer’s Disease (AD) is a progressive neurodegenerative disease where biomarkers for disease based on pathophysiology may be able to provide objective measures for disease diagnosis and staging. Neuroimaging scans acquired from MRI and metabolism images obtained by FDG-PET provide in-vivo measurements of structure and function (glucose metabolism) in a living brain. It is hypothesized that combining multiple different image modalities providing complementary information could help improve early diagnosis of AD. In this paper, we propose a novel deep-learning-based framework to discriminate individuals with AD utilizing a multimodal and multiscale deep neural network. Our method delivers 82.4% accuracy in identifying the individuals with mild cognitive impairment (MCI) who will convert to AD at 3 years prior to conversion (86.4% combined accuracy for conversion within 1–3 years), a 94.23% sensitivity in classifying individuals with clinical diagnosis of probable AD, and a 86.3% specificity in classifying non-demented controls improving upon results in published literature
Recommended from our members
The impact of PICALM genetic variations on reserve capacity of posterior cingulate in AD continuum
Phosphatidylinositolbinding clathrin assembly protein (PICALM) gene is one novel genetic player associated with late-onset Alzheimer’s disease (LOAD), based on recent genome wide association studies (GWAS). However, how it affects AD occurrence is still unknown. Brain reserve hypothesis highlights the tolerant capacities of brain as a passive means to fight against neurodegenerations. Here, we took the baseline volume and/or thickness of LOAD-associated brain regions as proxies of brain reserve capacities and investigated whether PICALM genetic variations can influence the baseline reserve capacities and the longitudinal atrophy rate of these specific regions using data from Alzheimer’s Disease Neuroimaging Initiative (ADNI) dataset. In mixed population, we found that brain region significantly affected by PICALM genetic variations was majorly restricted to posterior cingulate. In sub-population analysis, we found that one PICALM variation (C allele of rs642949) was associated with larger baseline thickness of posterior cingulate in health. We found seven variations in health and two variations (rs543293 and rs592297) in individuals with mild cognitive impairment were associated with slower atrophy rate of posterior cingulate. Our study provided preliminary evidences supporting that PICALM variations render protections by facilitating reserve capacities of posterior cingulate in non-demented elderly
Recommended from our members
Early role of vascular dysregulation on late-onset Alzheimer's disease based on multifactorial data-driven analysis
Multifactorial mechanisms underlying late-onset Alzheimer's disease (LOAD) are poorly characterized from an integrative perspective. Here spatiotemporal alterations in brain amyloid-β deposition, metabolism, vascular, functional activity at rest, structural properties, cognitive integrity and peripheral proteins levels are characterized in relation to LOAD progression. We analyse over 7,700 brain images and tens of plasma and cerebrospinal fluid biomarkers from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Through a multifactorial data-driven analysis, we obtain dynamic LOAD–abnormality indices for all biomarkers, and a tentative temporal ordering of disease progression. Imaging results suggest that intra-brain vascular dysregulation is an early pathological event during disease development. Cognitive decline is noticeable from initial LOAD stages, suggesting early memory deficit associated with the primary disease factors. High abnormality levels are also observed for specific proteins associated with the vascular system's integrity. Although still subjected to the sensitivity of the algorithms and biomarkers employed, our results might contribute to the development of preventive therapeutic interventions