Multiple processes regulate long-term population dynamics of sea urchins on Mediterranean rocky reefs

We annually monitored the abundance and size structure of herbivorous sea urchin populations (Paracentrotus lividus and Arbacia lixula) inside and outside a marine reserve in the Northwestern Mediterranean on two distinct habitats (boulders and vertical walls) over a period of 20 years, with the aim of analyzing changes at different temporal scales in relation to biotic and abiotic drivers. P. lividus exhibited significant variability in density over time on boulder bottoms but not on vertical walls, and temporal trends were not significantly different between the protection levels. Differences in densities were caused primarily by variance in recruitment, which was less pronounced inside the MPA and was correlated with adult density, indicating density-dependent recruitment under high predation pressure, as well as some positive feedback mechanisms that may facilitate higher urchin abundances despite higher predator abundance. Populations within the reserve were less variable in abundance and did not exhibit the hyper-abundances observed outside the reserve, suggesting that predation effects maybe more subtle than simply lowering the numbers of urchins in reserves. A. lixula densities were an order of magnitude lower than P. lividus densities and varied within sites and over time on boulder bottoms but did not differ between protection levels. In December 2008, an exceptionally violent storm reduced sea urchin densities drastically (by 50% to 80%) on boulder substrates, resulting in the lowest values observed over the entire study period, which remained at that level for at least two years (up to the present). Our results also showed great variability in the biological and physical processes acting at different temporal scales. This study highlights the need for appropriate temporal scales for studies to fully understand ecosystem functioning, the concepts of which are fundamental to successful conservation and management.

France's Charter for the Environment : of Presidents, Principles and Environmental Protection

France amended its constitution in 2005 to include a Charter for the Environment. The Charter lays out France's commitment to supporting the right to a 'balanced environment'. This article first traces the Charter's origins to a legacy-building presidential initiative. Jacques Chirac decided to invest in a neglected policy domain in which his own majority had shown little interest. He was obliged to intervene repeatedly in order to bring this project to a successful conclusion. In doing so, he staked out environmental affairs as an area of potential presidential supremacy. Next, the content of the Charter is examined. In this document, French traditions of universalism come together with an international movement for anticipatory environmental protection. This is reflected in the constitutionalisation of the precautionary principle, which emerged as the most controversial part of the Charter. The debates this provoked tended to caricature a risk-management principle whose meaning has been carefully refined to forestall objections. Finally, the Charter's potential efficacy is analysed. The post-Charter record of legislative and judicial activity concerning the environment is meagre, but not wholly inauspicious.

Evaluation de l'efficacité des moyens de protection collective et des équipements de protection individuelle vis-à-vis de l'exposition des travailleurs aux fibres courtes et fibres fines d'amiante : rapport présentant un état des lieux sur les connaissances et obligations relatives aux équipements de protection collective et individuelle amiante

[Table des matières] 1. Contexte, objet et modalités de traitement de la saisine ; Partie A : Exigences réglementaires, normatives et recensement des EPC-EPI amiante. - 2. Exigences réglementaires en matière de protection collective et individuelle contre l'amiante. - 3. Normes d'exigences pour les équipements de protection collective contre l'amiante. - 4. Aspirateurs à usage industriel. - 5. Norms d'exigences pour la protection individuelle contre l'amiante. - 6. Recensement des EPC et EPI en fonction des activités. - 7. Objectifs de la synthèse bibliographique. - 8. Rappels théoriques sur la filtration de l'air. - 9. Efficacité des équipements de protection collective contre l'amiante. - 10. Aspirateurs à usage industriel. - 11. Efficacité des équipements de protection individuelle. - 12. Comparaison de la filtration des fibres d'amiante ou autres particules non sphériques et des aérosols utilisés pour les essais normalisés (MPPS). - 13. Conclusion sur la synthèse bibliographique. - 14. Perspectives. - 15. Bibliographie. - Annexes

Using toxicokinetic modeling approach to determine biological reference values (BRVs) and to assess human exposure to pesticides

Exposure to various pesticides has been characterized in workers and the general population, but interpretation and assessment of biomonitoring data from a health risk perspective remains an issue. For workers, a Biological Exposure Index (BEI®) has been proposed for some substances, but most BEIs are based on urinary biomarker concentrations at Threshold Limit Value - Time Weighted Average (TLV-TWA) airborne exposure while occupational exposure can potentially occurs through multiple routes, particularly by skin contact (i.e.captan, chlorpyrifos, malathion). Similarly, several biomonitoring studies have been conducted to assess environmental exposure to pesticides in different populations, but dose estimates or health risks related to these environmental exposures (mainly through the diet), were rarely characterized. Recently, biological reference values (BRVs) in the form of urinary pesticide metabolites have been proposed for both occupationally exposed workers and children. These BRVs were established using toxicokinetic models developed for each substance, and correspond to safe levels of absorption in humans, regardless of the exposure scenario. The purpose of this chapter is to present a review of a toxicokinetic modeling approach used to determine biological reference values. These are then used to facilitate health risk assessments and decision-making on occupational and environmental pesticide exposures. Such models have the ability to link absorbed dose of the parent compound to exposure biomarkers and critical biological effects. To obtain the safest BRVs for the studied population, simulations of exposure scenarios were performed using a conservative reference dose such as a no-observed-effect level (NOEL). The various examples discussed in this chapter show the importance of knowledge on urine collections (i.e. spot samples and complete 8-h, 12-h or 24-h collections), sampling strategies, metabolism, relative proportions of the different metabolites in urine, absorption fraction, route of exposure and background contribution of prior exposures. They also show that relying on urinary measurements of specific metabolites appears more accurate when applying this approach to the case of occupational exposures. Conversely, relying on semi-specific metabolites (metabolites common to a category of pesticides) appears more accurate for the health risk assessment of environmental exposures given that the precise pesticides to which subjects are exposed are often unknown. In conclusion, the modeling approach to define BRVs for the relevant pesticides may be useful for public health authorities for managing issues related to health risks resulting from environmental and occupational exposures to pesticides.

Radiation protection in digestive endoscopy: European Society of Digestive Endoscopy (ESGE) guideline.

This article expresses the current view of the European Society of Gastrointestinal Endoscopy (ESGE) about radiation protection for endoscopic procedures, in particular endoscopic retrograde cholangiopancreatography (ERCP). Particular cases, including pregnant women and pediatric patients, are also discussed. This Guideline was developed by a group of endoscopists and medical physicists to ensure that all aspects of radiation protection are adequately dealt with. A two-page executive summary of evidence statements and recommendations is provided. The target readership for this Guideline mostly includes endoscopists, anesthesiologists, and endoscopy assistants who may be exposed to X-rays during endoscopic procedures.

Secretory IgA and intestinal epithelial cells at the interface between homeostasis regulation and protection against infection

RESUME DESTINE A UN LARGE PUBLICL'intestin est le siège d'intenses agressions de la part de l'ensemble des aliments ingérés, de bactéries agressives dites pathogènes mais également de bactéries dites commensales peuplant naturellement les surfaces intestinales muqueuses. Pour faire face, notre organisme arbore de nombreux niveaux de protections tant physiques, chimiques, mécaniques mais aussi immunitaires. La présence d'un type particulier de cellules, les cellules épithéliales (IEC) assurant une protection physique, ainsi que la production d'anticorps spécialisés par le système immunitaire appelés immunoglobulines sécrétoires A (SlgA) servent conjointement de première ligne de défense contre ces agressions externes. Néanmoins, comment le dialogue s'articule entre ces deux partenaires reste incomplet.Nous avons donc décidé de mimer ces interactions en modélisant les surfaces muqueuses par une monocouche de cellules différenciées en laboratoire. Des souches bactériennes isolées de l'intestin humain seules ou associées à des SlgA non-spécifiques ont été mises au contact de ce modèle cellulaire nous permettant de conclure quant à la présence effective d'une modulation du dialogue bactérie/lEC impliquant une activation de la réponse cellulaire vers un état de tolérance mutuelle. De façon surprenante, nous avons par ailleurs mis en évidence un type d'interaction nouveau entre ces anticorps et ces bactéries. Une étude biochimique nous a permis de détailler un nouveau rôle des SlgA médié par les sucres présents à leur surface dans le maintien d'une relation pacifique avec les commensaux perpétuellement présents, relations qualifiées d'homésostase intestinale.Le rôle protecteur des SlgA a par ailleurs été abordé pour avoir une meilleure appréhension de leur impact au niveau cellulaire lors d'infection par Shigella flexneri, bactérie causant la Shigellose, diarrhée sanglante responsable de la mort de plus d'un million de personnes chaque année. Basée sur le même modèle cellulaire, cette étude nous a permis de démontrer une nouvelle entrée de ce pathogène directement via les IEC. La présence d'anticorps spécifiques à la surface des bactéries restreint leur champs d'action contre les cibles intracellulaires identifiées que sont les filaments soutenant le squelette de la cellule, les fibres d'actine ainsi que les jonctions serrées, réseaux de protéines clés des interactions entre cellules. Cette ouverture au niveau cellulaire apporte un nouvel élan quant à la compréhension du rôle protecteur des SlgA lors d'attaques de l'intestin, protection semblant dépendante d'une agrégation des bactéries.Pour finir, nous avons mis en évidence la détection directe par les cellules de la présence d'anticorps libres dans l'intestin ajoutant une nouvelle réplique dans le dialogue complexe entre ces deux piliers de l'équilibre intestinal que sont les SlgA et les cellules épithéliales.RESUMELa muqueuse intestinale est dotée d'un réseau complexe de protections physico-chimiques, mécaniques ou immunologiques. Associées à un système immunitaire omniprésent, les cellules épithéliales intestinales {IEC) bordant la lumière intestinale ont la double tâche de protéger l'intérieur de l'organisme stérile contre l'invasion et la dissémination d'agents pathogènes, et de maintenir une relation pacifique avec la flore intestinale, rôles également joués par les immunoglobulines sécrétoires A (SlgA), anticorps les plus abondamment présents à la surface des muqueuses. Tant les IEC que les SlgA sont ainsi décrites comme convergeant vers le même objectif ; néanmoins, les rouages de leurs interactions restent largement inconnus.Pour répondre à cette question, des monocouches épithéliales reconstituées in vitro ont été incubées avec des souches commensales telles que des Lactobacillus ou des Bifodobacteria, seules ou complexées avec des SlgA non-spécifiques, nous permettant de décrypter l'influence des SlgA sur la détection des bactéries par les IEC, favorisant l'adhésion bactérienne et la cohésion cellulaire, augmentant l'activation de la voie NF-κΒ ainsi que la sécrétion de la cytokine thymic stromal lymphopoietin contrairement à celle de médiateurs pro-inflammatoires qui reste inchangée. Par ailleurs, une interaction Fab-indépendante est suggérée dans l'interaction SlgA/bactéries. Comme une interaction de faible affinité a été décrite comme prenant naturellement place au niveau de l'intestin, nous avons donc disséqué les mécanismes sous- jacents en utilisant un large spectre de bactérie associés à des protéines soit recombinantes soit isolées à partir de colostrum, mettant en évidence un rôle crucial des N-glycanes présents sur la pièce sécrétoire et soulignant une nouvelle propriété des SlgA dans l'homéostase intestinale.Intrinsèquement liés aux caractéristiques des SlgA, nous nous sommes également focalisés sur leur rôle protecteur lors d'infection par l'enteropathogène Shigella flexneri reproduites in vitro sur des monocouches polarisées. Nous avons tout d'abord démontré une nouvelle porte d'entrée pour ce pathogène directement via les IEC. L'agrégation des bactéries par les SlgA confère aux cellules une meilleure résistance à l'infection, retardant croissance bactérienne et entrée cellulaire, affectant par ailleurs leur capacité à cibler le cytosquelette et les jonctions serrées. La formation de tels cargos détectés de façon biaisée par les IEC apparaît comme une explication plausible au maintien de la cohésion cellulaire médiée par les SlgA.Enfin, le retrotransport des SlgA à travers les IEC a été abordé soulignant une participation active de ces cellules dans la détection de l'environnement extérieur, les impliquant possiblement dans l'activation d'un état muqueux stable.Conjointement, ces résultats indiquent que les SlgA représentent l'un des éléments-clés à la surface de la muqueuse et soulignent la complexité du dialogue établi avec l'épithélium en vue du maintien d'un fragile équilibre intestinal.ABSTRACTThe intestinal mucosa is endowed with a complex protective network melting physiochemical, mechanical and immunological features. Beyond the ubiquitous intestinal immune system, intestinal epithelial cells (IEC) lying the mucosal surfaces have also the dual task to protect the sterile core against invasion and dissemination of pathogens, and maintain a peaceful relationship with commensal microorganisms, aims also achieved by the presence of high amounts of secretory immunoglobulins A (SlgA), the most abundant immunoglobulin present at mucosal surfaces. Both IEC and SlgA are thus described to converge toward the same goal but how their interplay is orchestrated is largely unknown.To address this question, in vitro reconstituted IEC monolayers were first apically incubated with commensal bacteria such as Lactobacillus or Bifodobacteria strains either alone or in complexes with non-specific SlgA. Favoring the bacterial adhesion and cellular cohesion, SlgA impacts on the cellular sensing of bacteria, increasing NF-κΒ activation, and leading to cytokine releases restricted to the thymic stromal lymphopoietin and unaffected expression of pro-inflammatory mediators. Of main interest, bacterial recognition by SlgA suggested a Fab-independent interaction. As this low affinity, called natural coating occurs in the intestine, we further dissected the underlying mechanisms using a larger spectrum of commensal strains associated with recombinant as well as colostrum-derived proteins and pinpointed a crucial role of N-glycans of the secretory component, emphasizing an underestimated role of carbohydrates and another properties of SlgA in mediating intestinal homeostasis.As mucosal protection is also anchored in SlgA and IEC features, we focused on the cellular role of SlgA. Using IEC apical infection by the enteropathogen Shigella flexneri, we have first demonstrated a new gate of entry for this pathogen directly via IEC. Specific SlgA bacterial aggregation conferred to the cells a better resistance to infection, delaying bacterial growth and cellular entry, affecting their ability to damage both the cytoskeleton and the tight junctions. Formation of such big cargos differentially detected by IEC appears as a plausible explanation sustaining at the cellular level the antibody-mediated mucosal protection.Finally, SlgA retrotransport across IEC has been tackled stressing an active IEC sensing of the external environment possibly involved in the steady-state mucosal activation.All together, these results indicate that SlgA represents one of the pivotal elements at mucosal surfaces highlighting the complexity of the dialogue established with the epithelium sustaining the fragile intestinal balance.The Intestinal mucosa is endowed with a complex protective network melting physiochemical, mechanical and immunological features. Beyond the ubiquitous intestinal immune system, intestinal epithelial cells (IEC) lying the mucosal surfaces have also the dual task to protect the sterile core against invasion and dissemination of pathogens, and maintain a peaceful relationship with commensal microorganisms, aims also achieved by the presence of high amounts of secretory immunoglobulins A (SlgA), the most abundant immunoglobulin present at mucosal surfaces. Both IEC and SlgA are thus described to converge toward the same goal but how their interplay is orchestrated is largely unknown.To address this question, in vitro reconstituted IEC monolayers were first apically incubated with commensal bacteria such as Lactobacillus or Bifodobacteria strains either alone or in complexes with non-specific SlgA. Favoring the bacterial adhesion and cellular cohesion, SlgA impacts on the cellular sensing of bacteria, increasing NF-κΒ activation, and leading to cytokine releases restricted to the thymic stromal lymphopoietin and unaffected expression of pro-inflammatory mediators. Of main interest, bacterial recognition by SlgA suggested a Fab-independent interaction. As this low affinity, called natural coating occurs in the intestine, we further dissected the underlying mechanisms using a larger spectrum of commensal strains associated with recombinant as well as colostrum-derived proteins and pinpointed a crucial role of N-glycans of the secretory component, emphasizing an underestimated role of carbohydrates and another properties of SlgA in mediating intestinal homeostasis.As mucosal protection is also anchored in SlgA and IEC features, we focused on the cellular role of SlgA. Using IEC apical infection by the enteropathogen Shigella flexneri, we have first demonstrated a new gate of entry for this pathogen directly via IEC. Specific SlgA bacterial aggregation conferred to the cells a better resistance to infection, delaying bacterial growth and cellular entry, affecting their ability to damage both the cytoskeleton and the tight junctions. Formation of such big cargos differentially detected by IEC appears as a plausible explanation sustaining at the cellular level the antibody-mediated mucosal protection.Finally, SlgA retrotransport across IEC has been tackled stressing an active IEC sensing of the external environment possibly involved in the steady-state mucosal activation.All together, these results indicate that SlgA represents one of the pivotal elements at mucosal surfaces highlighting the complexity of the dialogue established with the epithelium sustaining the fragile intestinal balance.

Coagulation Factor Xa Activates Thrombin and Signals Ischemic Neuronal Death Via Par-1 and JNK in Ischemic Neural Tissue

Background: The coagulation factor thrombin mediates ischemic neuronal deathand, at a low concentration, induces tolerance to ischemia.We investigated its modeof activation in ischemic neural tissue using an in vitro approach to distinguish therole of circulating coagulation factors from endogenous cerebral mechanisms. Wealso studied the signalling pathway downstream of thrombin in ischemia and afterthrombin preconditioning.Methods: Rat organotypic hippocampal slice cultures to 30 minute oxygen (5%)and glucose (1 mmol/L) deprivation (OGD).Results: Selective factor Xa (FXa) inhibition by fondaparinux during and afterOGD significantly reduced neuronal death in the CA1 after 48 hours. Thrombinactivity was increased in the medium 24 hours after OGD and this increasewas prevented by fondaparinux suggesting that FXa catalyzes the conversion ofprothrombin to thrombin in neural tissue after ischemia in vitro. Treatment withSCH79797, a selective antagonist of the thrombin receptor protease activatedreceptor-1 (PAR-1), significantly decreased neuronal cell death indicating thatthrombin signals ischemic damage via PAR-1. The JNK pathway plays an importantrole in cerebral ischemia and we observed activation of the JNK substrate,c-Jun in our model. Both the FXa inhibitor, fondaparinux and the PAR-1 antagonistSCH79797, decreased the level of phospho-c-Jun Ser73. After thrombin preconditioningc-Jun was activated by phosphorylation in the nuclei of neurons of the CA1.Treatment with a synthetic thrombin receptor agonist resulted in the same c-Junactivation profile and protection against subsequent OGD indicating that thrombinalso signals via PAR-1 and c-Jun in cell protection.Conclusion: These results indicate that FXa activates thrombin in cerebral ischemia,leading via PAR-1 to the activation of the JNK pathway resulting in neuronal death.Thrombin induced tolerance also involves PAR-1 and JNK, revealing commonfeatures in cell death and survival signalling.

Submerged Vanes for Flow Control and Bank Protection in Streams, HR-255, 1984

This study was conducted for the purpose of evaluating a new concept for a bank-protection structure: The Iowa Vane . The underlying idea involves countering the torque exerted on the primary flow by its curvature and vertical velocity gradient, thereby eliminating or significantly reducing the secondary flow and thus reducing the undermining of the outer banks and the high-velocity attack on it. The new structure consists of an array of short, vertical, submerged vanes installed with a certain orientation on the channel bed. A relatively small number of vanes can produce bend flows which are practically uniform across the channel. The height of the vanes is less than half the water depth, and their angle with the flow direction is of the order of l0 degrees. In this study, design relations have been established. The relations, and the vanes' overall performance, have been tested in a laboratory model under different flow and sediment conditions. The results are used for the design of an Iowa-Vane bank protection structure for a section of East Nishnabotna River along U.S. Highway 34 at Red Oak, Iowa.

Ascending aorta measurements as assessed by ECG-gated multi-detector computed tomography: a pilot study to establish normative values for transcatheter therapies

The aim of this study was to provide an insight into normative values of the ascending aorta in regards to novel endovascular procedures using ECG-gated multi-detector CT angiography. Seventy-seven adult patients without ascending aortic abnormalities were evaluated. Measurements at relevant levels of the aortic root and ascending aorta were obtained. Diameter variations of the ascending aorta during cardiac cycle were also considered. Mean diameters (mm) were as follows: LV outflow tract 20.3 +/- 3.4, coronary sinus 34.2 +/- 4.1, sino-tubular junction 29.7 +/- 3.4 and mid ascending aorta 32.7 +/- 3.8 with coefficients of variation (CV) ranging from 12 to 17%. Mean distances (mm) were: from the plane passing through the proximal insertions of the aortic valve cusps to the right brachio-cephalic artery (BCA) 92.6 +/- 11.8, from the plane passing through the proximal insertions of the aortic valve cusps to the proximal coronary ostium 12.1 +/- 3.7, and between both coronary ostia 7.2 +/- 3.1, minimal arc of the ascending aorta from left coronary ostium to right BCA 52.9 +/- 9.5, and the fibrous continuity between the aortic valve and the anterior leaflet of the mitral valve 14.6 +/- 3.3, CV 13-43%. Mean aortic valve area was 582.0 +/- 131.9 mm(2). The variation of the antero-posterior and transverse diameters of the ascending aorta during the cardiac cycle were 8.4% and 7.3%, respectively. Results showed large inter-individual variations in diameters and distances but with limited intra-individual variations during the cardiac cycle. A personalized approach for planning endovascular devices must be considered.