129 research outputs found
Histologie de la peau et des follicules pileux
La peau est complexe, morphologiquement et biochimiquement. Le défi de ces dernières années a été de localiser précisément ses molécules de structure. Dans cet article, l’histologie normale de la peau et des follicules pilo-sébacés est brièvement décrite avec une iconographie en microscopies optique et électronique, afin de mieux comprendre où sont situées les molécules jouant un rôle clé dans la cohésion et la différenciation de l’épiderme, la mélanogenèse, la présentation des antigènes aux lymphocytes T, l’adhérence dermo-épidermique, la résistance et l’élasticité du derme et de l’hypoderme et, enfin, le renouvellement des follicules pileux. Les données présentées ont été établies par la confrontation d’études en peau normale, sur des souris invalidées et chez des patients souffrant de pathologies auto-immunes ou de génodermatoses. L’histologie moléculaire de la peau éclaire sous un autre jour la physiologie de la peau ; elle doit être connue pour valider les essais de thérapie génique ou cellulaire.The skin consists of an outer epidermis, the dermis, and the hypodermis. It includes nerves, blood vessels, glands and hair follicles. Epidermis is a continually renewing, stratified squamous epithelium. It is populated by keratinocytes (80 %) and dendritic cells (20 %) : melanocytes, Langerhans and Merkel cells. In standard histology, keratinocytes are arranged in layers that represent different stages of their differentiation while melanocytes and Langerhans cells appear as clear cells respectively between the basal and the supra-basal cells of epidermis. The Merkel cells cannot be clearly identified. Dendritic processes of the dendritic cells can only be recognized by immunocytochemistry. At the dermal-epidermal junction, a PAS reactive basement membrane follows the contour of the basal cells. Dermis consists of collagenous and elastic fibers embedded into an amorphous ground substance. Fibroblasts, macrophages, mast cells and lymphocytes are its resident cells. Hypodermis is composed of adipocyte lobules defined by fibrous connective tissue septa. Hair follicle consists of 3 parts : the lower portion, from the base of the follicle including hair bulb to the insertion of the arrector pili muscle or buldge ; the isthmus, from the insertion of the arrector pili to the entrance of the sebaceous duct, and the infundibulum, from the entrance of the sebaceous duct to the follicular orifice. The lower portion is composed of the dermal hair papilla, the hair matrix, the hair, and the inner and the outer root sheaths. The hair matrix cells within hair bulb give rise to the hair and to the inner root sheath. With the electron microscope, one can obtain a more detailed view of the characteristic skin structures. Much of them can now be explained in terms of function and in many instances, in correlation with its biochemical composition. An attempt has been made in this paper to precisely give the location of molecules that are relevant in basic skin functions and understanding of auto-immune and genetic diseases
Hydrochemical impatcs of CO2 leakage on fresh groundwater; A field scale experiment
One of the questions related to the emerging technology for Carbon Geological Storage concerns the risk of CO2 migration beyond the geological storage formation. In the event of leakage toward the surface, the CO2 might affect resources in neighbouring formations (geothermal or mineral resources, groundwater) or even represent a hazard for human activities at the surface or in the subsurface. In view of the preservation of the groundwater resources mainly for human consumption, this project studies the potential hydrogeochemical impacts of CO2 leakage on fresh groundwater quality. One of the objectives is to characterize the bio-geochemical mechanisms that may impair the quality of fresh groundwater resources in case of CO2 leakage. To reach the above mentioned objectives, this project proposes a field experiment to characterize in situ the mechanisms having an impact on water quality and the CO2-water-rock interactions and also to improve the monitoring methodology by controlled CO2 leakage in shallow aquifer. The tests ran on an experimental site in the chalk formation of the Paris Basin. The site is equipped with an appropriate instrumentation and previously characterized (8 piezometers, 25 m deep and 4 piezairs 11 m deep). The injection test was preceded by 6 months of monitoring in order to characterize hydrodynamics and geochemical baselines of the site (groundwater, vadose and soil). Leakage into groundwater is simulated via the injection of a small quantity of food quality CO2 (~20 kg dissolved in 10 m3 of water) in the injection well at a depth of about 20 m. A plume of dissolved CO2 is formed and moves downward according to the direction of groundwater flow and probably by degassing in part to the surface. During the injection test, hydrochemical monitoring of the aquifer is done in situ and by sampling. The parameters monitored in the groundwater are the piezometric head, temperature, pH and electrical conductivity. Analysis on water samples provide chemical elements (major, minor and trace metals), dissolved gases, microbiological diversity and isotopes (13C). The evolution of the composition of the groundwater in terms of major elements, trace elements and isotope signatures is interpreted in terms of geochemical mechanisms, and the water-rock-CO2 interactions are characterised. Modification of the chemical composition of the water in the aquifer due to CO2 injection is assessed in term of groundwater quality i.e. metal element release and the possibility of exceeding references and quality of water for human consumption. One outcome of the CIPRES project will be to highlight mechanisms that can impact groundwater quality when a CO2 leakage occurs and to propose recommendations to prevent or/and eliminate negative effects and any risks to the environment and human health. This project is partially funded by the French Research Agency (ANR)
CO2 leakage in a shallow aquifer - Observed changes in case of small release
International audienceGeological storage of CO2 in deep saline aquifers is one of the options considered for the mitigation of CO2 emissions into the atmosphere. A deep geological CO2 storage is not expected to leak but potential leakage monitoring is required by legislation, as e.g. the EU Directive relative to Geological Storage of CO2. To ensure that the storage will be permanent and safe for the environment and human health, the legislation require that the CCS operators monitor the injection, the storage complex and if needed the environment to detect any CO2 leakage and its hazardous effects on the environment. Various monitoring methods are available for the monitoring of CO2 storage sites and the environment as listed by the IEA-GHG and the monitoring selection tool. Geophysical based methods have a greater area of investigation but may suffer from insufficient sensitivities to detect small leakages. At the opposite, geochemical monitoring methods may have insufficient investigation area but may be able to detect more subtle changes even if monitoring in deep environments is not straightforward. Leakage detection is not yet well constrained and research efforts and tests are required to gain confidence into monitoring strategies. In the framework of the CIPRES project, funded by the French Research Agency, a shallow CO2 release experiment has been performed in October 2013 in a chalk aquifer from the Paris basin. The Catenoy site has been characterised since March 2013 through several wells set on a straight line oriented along the local flow (see Gombert et al., this conference). Such an experiment is designed to gain confidence in leakage detection in subsurface environments by understanding processes and principles governing seepage occurrence. Contrary to other experiments such as ZERT or CO2FieldLab ones, where gaseous CO2 was injected directly in the water, the injection was done with water saturated with CO2 at atmospheric pressure. 10 m3 of water were pumped from the aquifer, then saturated with 20 kg of food-grade CO2 and injected during 40 hours between 12 and 25 m depth. Daily monitoring of soil gases and water was performed during injection and post-injection phases (2 weeks duration) in the area previously delimited by a tracer test. The aim is to determine if geochemical methods are accurate enough to allow detecting small release in shallow environments. If successful, such an experiment can help to gain confidence in leakage detection. As expected, no change was noticed in the unsaturated zone. The shape of gas concentrations distribution at the surface (CO2, O2, N2, 4He, 222Rn) observed during the injection is strictly similar to the repartition of gas species observed since March 2013. The main process observed is respiration and no change linked to the injection was highlighted, only seasonal effects. Slight changes were observed in the saturated zone. The water was collected at 15 m deep excepted for one stratified borehole where water was sampled at 15 and 18 m. The pH of the injected water was lower (mean value: 5.3±0.1) than the initial pH of the aquifer (7.1-7.2) due to CO2 dissolution. Only two monitoring boreholes set 10 m and 20 m downstream from the injection well may be considered as influenced by the experiment. A probable enrichment in HCO3 linked to interaction of the CO2 saturated water with chalk was noticed, with an enrichment close to +8 to +10% of the initial value. For one borehole the pH value remained nearly stable in relation with pH buffering and in the other borehole a slight decrease was observed (-0.1 to -0.15 pH unit). However this decrease is significant as it is above the instrumental uncertainty of the electrodes. In addition, a slight increase of the electrical conductivity was noticed but it did not exceed +6% compared to baseline data. Such slight changes in the physico-chemical parameters are related to small variations in dissolved elements. Apart from HCO3, the other major ion affected by CO2-water rock-interaction is Ca as the aquifer is mainly composed by calcite. Concentrations increases by +8 to +9% whose amplitude is in agreement with the increase of HCO3. Trace elements were also little affected, the main change concerned Sr (+8 to +10% increase). Modifications occurring during this CO2 release experiment have small amplitude as expected but these results highlight that geochemical methods are able to detect small leakages. Consequently, effects were noticed only during a short period of time. It is not possible to determine if all the injected CO2 has migrated downwards in the direction of flow or if partial lateral migration has occurred, but post-injection monitoring and boreholes logging 12 days after the stop of injection did not reveal any discrepancy in the water columns. On the other hand, the magnitude of the pH change is consistent with the behaviour of the co-injected tracer (dilution ratio ~30). In the perspective of getting more information on the remobilisation of trace metal elements, a push-pull test will be performed in 2014 on the basis of the learning of this first experiment
CO2 leakage in a shallow aquifer – Observed changes in case of small release
AbstractGeological storage of CO2 in deep saline aquifers is one of the options considered for the mitigation of CO2 emissions into the atmosphere. A deep geological CO2 storage is not expected to leak but potential leakage monitoring is required by legislation, as e.g. the EU Directive relative to Geological Storage of CO2. To ensure that the storage will be permanent and safe for the environment and human health, the legislation require that the CCS operators monitor the injection, the storage complex and if needed the environment to detect any CO2 leakage and its hazardous effects on the environment. Various monitoring methods are available for the monitoring of CO2 storage sites and the environment as listed by the IEA-GHG and the monitoring selection tool. Geophysical based methods have a greater area of investigation but may suffer from insufficient sensitivities to detect small leakages. At the opposite, geochemical monitoring methods may have insufficient investigation area but may be able to detect more subtle changes even if monitoring in deep environments is not straightforward. Leakage detection is not yet well constrained and research efforts and tests are required to gain confidence into monitoring strategies.In the framework of the CIPRES project, funded by the French Research Agency, a shallow CO2 release experiment has been performed in October 2013 in a chalk aquifer from the Paris basin. The Catenoy site has been characterised since March 2013 through several wells set on a straight line oriented along the local flow (see Gombert et al., this conference). Such an experiment is designed to gain confidence in leakage detection in subsurface environments by understanding processes and principles governing seepage occurrence. Contrary to other experiments such as ZER
Selection, Instrumentation and Characterization of a Pilot Site for CO2 Leakage Experimentation in a Superficial Aquifer
AbstractCO2 geological storage is one of the options for mitigation of GHG emissions into the atmosphere. Although storage is provided for several millennia, leakage can occur. Therefore the risk that the fugitive CO2 reaches a shallow aquifer cannot be excluded [1]. That is why the consortium launched the research program CIPRES, funded by the French Research Agency, concerning the potential impacts of CO2 leakage on groundwater quality. This program includes the realization of a shallow CO2 release experiment in a carbonated aquifer and its monitoring in the saturated and unsaturated zones, the soil and the soil-atmosphere interface. The experimentation consists in drilling a well into the aquifer, injecting dissolved CO2 in water [2] and tracking its impact downstream. Prior to this experiment, a site had to be selected, instrumented and characterized.Hydrogeological target is the Paris basin chalk which is the largest French aquifer. The selected area is a large parcel, formerly cultivated in intensive monoculture but left fallow for several years, located in Catenoy (Oise) about 50km north of Paris. The geological log shows the chalk is covered by 6-7 m of sands but water table is located at 12-13 m depth, i.e. integrally in the chalk strata.The site has been equipped with 10 wells to characterize the groundwater flow (hydraulic gradient ∼5 10-3). 6 wells are aligned in the groundwater flow direction: the PZ2, planned for CO2 injection, the PZ1 located 20 m upstream and 4 monitoring wells located downstream between 10 and 60 m from PZ2. There are also 4 lateral piezometers located near (PZ7, PZ8) and far (PZ9, PZ10) from the injection site: they are dedicated to the lateral plume. These 25 m depth wells are equipped with tubing fully slotted in the chalk. Alongside, 4 wells dedicated to gas monitoring in unsaturated zone have been drilled at 11m depth.To characterize the site, the following operations were performed prior to the CO2 injection between March and September 2013:•pump test into PZ2 to estimate the hydraulic conductivity (10-3 m.s-1) and the storage coefficient (1.6%); the hydraulic conductivity is higher in the first 3 m of saturated zone (∼5 10-3 m.s-1);•hydrogeochemical baseline with monthly water analysis in each well (physicochemical parameters, major and minor ions, metallic trace elements); electrical conductivity is 714μs.cm-1 and groundwater has a calcium-bicarbonated facies with high nitrate concentration (45mg.l-1) and low-level presence of trace metals;•gas baseline with continuous O2 and CO2 measurement in vadose trough 11 m depth boreholes and measurements campaigns to determine gas concentration in the soil and gas flux on the surface;•flowmeter heatpulse logging at PZ2, PZ3 and PZ4 in static and dynamic conditions; only the area situated from 15 m to 20 m depth is productive and a vertical natural downflow is measured in PZ3 (∼1-2mm.s-1) and PZ4 (1cm.s-1); furthermore, no flow is measured from 20 to 25 m depth; this confirms the vertical anisotropy of the chalky aquifer;Following this experiments, a tracer test has been done in June 2013 from PZ2 with fluorescent tracer (amino-acid G) and a dissolved gas (He), in the way to calibrate the future CO2 injection and its monitoring. 2 m3 of water from the aquifer were pumped the day before the injection and stored in tanks. Then 2kg of tracer were dissolved and water was saturated with He. This water was injected into the PZ2 the next day during 8h. The monitoring was conducted for a month by water sampling, tracer and He analyzes. The peak of fluorescent tracer arrived at the 2nd day following injection in the PZ4 (20 m downstream) but only one week later in the PZ3 (10 m downstream), due to the site anisotropy. Low He concentrations have been detected in the unsaturated zone of PZ4 before PZ3, in correlation with tracer migration.The main result is the existence of an high aquifer anisotropy in such a small area: i) the first 3 m of the saturated zone shows a higher permeability and the last 5 m a lower one, ii) the tracer arrives quickly and with higher concentration at PZ4 located 10 m farther than PZ3. However, the dilution ratio is rather important and may induce, during CO2 leakage experimentation, a slight pH decrease at the downstream wells: in order to increase the impact of the CO2 leakage, we have therefore planned to inject a higher volume (10 m3) of CO2 saturated water
Epidermolysis Bullosa Acquisita: The 2019 Update
Epidermolysis bullosa acquisita (EBA) is an orphan autoimmune disease. Patients with EBA suffer from chronic inflammation as well as blistering and scarring of the skin and mucous membranes. Current treatment options rely on non-specific immunosuppression, which in many cases, does not lead to a remission of treatment. Hence, novel treatment options are urgently needed for the care of EBA patients. During the past decade, decisive clinical observations, and frequent use of pre-clinical model systems have tremendously increased our understanding of EBA pathogenesis. Herein, we review all of the aspects of EBA, starting with a detailed description of epidemiology, clinical presentation, diagnosis, and current treatment options. Of note, pattern analysis via direct immunofluorescence microscopy of a perilesional skin lesion and novel serological test systems have significantly facilitated diagnosis of the disease. Next, a state-of the art review of the current understanding of EBA pathogenesis, emerging treatments and future perspectives is provided. Based on pre-clinical model systems, cytokines and kinases are among the most promising therapeutic targets, whereas high doses of IgG (IVIG) and the anti-CD20 antibody rituximab are among the most promising “established” EBA therapeutics. We also aim to raise awareness of EBA, as well as initiate basic and clinical research in this field, to further improve the already improved but still unsatisfactory conditions for those diagnosed with this condition
International bullous diseases group: consensus on diagnostic criteria for epidermolysis bullosa acquisita
BACKGROUND:
Epidermolysis bullosa acquisita (EBA) is a complex autoimmune bullous disease disease with variable clinical presentations and multiple possible diagnostic tests, making an international consensus on the diagnosis of EBA essential. -----
OBJECTIVES:
To obtain an international consensus on the clinical and diagnostic criteria for EBA. -----
METHODS:
The International Bullous Diseases Group (IBDG) met three times to discuss the clinical and diagnostic criteria for EBA. For the final voting exercise, 22 experts from 14 different countries voted on 50 different items. When > 30% disagreed with a proposal, a discussion was held and re-voting carried out. -----
RESULTS:
In total, 48 of 50 proposals achieved consensus after discussion. This included nine diagnostic criteria, which are summarized in a flow chart. The IBDG was unable to determine one procedure that would be applicable worldwide. A limitation of the study is that differential diagnosis of bullous systemic lupus erythematosus has not been addressed. -----
CONCLUSIONS:
This first international consensus conference established generally agreed-upon clinical and laboratory criteria defining the clinical classification of and diagnostic testing for EBA. Holding these voting exercises in person with the possibility of discussion prior to voting has advantages in reaching consensus over Delphi exercises with remote voting
Faire face aux règles du PS et de l'UMP : une analyse du comportement des candidats en France
Party on the Ground and Candidate Selection in France (1969-2013): The Story of a Difficult Inclusion
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