Search

Résumé Les techniques viscoélastiques sont utilisées depuis une dizaine d’année et comprennent le ROTEM ® et le TEG ® . Ces outils en utilisant les propriétés viscoélastiques du caillot vont permettre un diagnostic rapide des troubles de l’hémostase mais également une analyse globale de l’hémostase prenant en compte les phénomènes intercurrents tels que l’inflammation. L’utilisation de ces techniques dans des situations variées telles que la traumatologie, les hémorragies du post-partum ou digestive, la chirurgie cardiaque, vont réduire la consommation de produits sanguins labiles, diminuer le coût de la prise en charge et peut être améliorer le pronostic des patients. De plus, ces techniques permettant un diagnostic ciblé des troubles de l’hémostase, vont autoriser le développement de traitement ciblé avec des concentrés de facteurs de coagulation. Viscoelastic technics are used for 10 years and include the ROTEM ® and the TEG ® . These devices that exploit the viscoelastic properties of the clotting blood, allow a rapid and global analysis of the haemostatic process taking into account all the process interfering with haemostasis such as inflammation. It has been shown that the use of these technics in clinical situations such as trauma, postpartum haemorrhage, gastrointestinal bleeding or cardiac surgery may reduce the need for blood product, the cost and perhaps may improve the outcome of the patients. Thanks to a rapid identification of the underlying coagulation deficit, these technics facilitate decision-making during acute care and help to guide the treatment, particularly with coagulation factor's concentrate. [ABSTRACT FROM AUTHOR]

Functional ecology is a subdiscipline that aims to enable a mechanistic understanding of patterns and processes from the organismic to the ecosystem level. This paper addresses some main aspects of the process-oriented current knowledge on phagotrophic, i.e. heterotrophic and mixotrophic, protists in aquatic food webs. This is not an exhaustive review; rather, we focus on conceptual issues, in particular on the numerical and functional response of these organisms. We discuss the evolution of concepts and define parameters to evaluate predator–prey dynamics ranging from Lotka–Volterra to the Independent Response Model. Since protists have extremely versatile feeding modes, we explore if there are systematic differences related to their taxonomic affiliation and life strategies. We differentiate between intrinsic factors (nutritional history, acclimatisation) and extrinsic factors (temperature, food, turbulence) affecting feeding, growth, and survival of protist populations. We briefly consider intraspecific variability of some key parameters and constraints inherent in laboratory microcosm experiments. We then upscale the significance of phagotrophic protists in food webs to the ocean level. Finally, we discuss limitations of the mechanistic understanding of protist functional ecology resulting from principal unpredictability of nonlinear dynamics. We conclude by defining open questions and identifying perspectives for future research on functional ecology of aquatic phagotrophic protists. [ABSTRACT FROM AUTHOR]

Bone morphogenetic protein-1 (BMP-1)/tolloid-like proteinases, here called BTPs, include the proteases originally identified for their roles in the C-terminal maturation of fibrillar procollagens (“procollagen C-proteinase”). Though numerous other substrates have since been discovered, the BTPs remain the main proteases involved in extracellular matrix assembly with little or no implication in matrix degradation. During the same period however, the BTPs have also become established as important proteases in the activation of growth factors, including TGF-β1, BMP-2/-4, GDF-8/-11 and IGFs, as well as the release of anti-angiogenic fragments from parent proteins. The BTPs are therefore key players in many pathophysiological processes such as morphogenesis, tissue repair and tumor progression. This mini-review summarizes our current knowledge of the functions of BTPs, their substrates and unusual mechanisms of regulation, and discusses their potential as new targets for future therapies. [ABSTRACT FROM AUTHOR]

Incorporating protozoa into population models (from simple predator-prey explorations to complex food web simulations) is of conceptual, ecological, and economic importance. From theoretical and empirical perspectives, we expose unappreciated complexity in the traditional predator-prey model structure and provide a parsimonious solution, especially for protistologists. We focus on how prey abundance alters two key components of models: predator conversion efficiency ( e , the proportion of prey converted to predator, before mortality loss) and predator mortality (δ, the portion of the population lost though death). Using a well-established model system ( Paramecium and Didinium ), we collect data to parameterize a range of existing and novel population models that differ in the functional forms of e and δ. We then compare model simulations to an empirically obtained time-series of predator-prey population dynamics. The analysis indicates that prey-dependent e and δ should be considered when structuring population models and that both prey and predator biomass also vary with prey abundance. Both of these impact the ability of the model to predict population dynamics and, therefore, should be included in theoretical model evaluations and assessment of ecosystem dynamics associated with biomass flux. [ABSTRACT FROM AUTHOR]

Aquatic biogeochemical models that include zooplankton feeding on phytoplankton assess a range of ecologically important issues. Such models generally assume assimilation efficiency (e) to be invariant with prey abundance. We first review the literature and make a strong case for recognising and quantifying the general dependence of e on prey abundance. Then, using two standard, fundamental multi-trophic models (the Rosenzweig–MacArthur, RM, predator–prey couplet and the nutrient-phytoplankton-zooplankton, NPZ, models) we explore how varying e with prey abundance alters the outcome of models. Incorporating variable e into both models altered their dynamics, potentially in important and counterintuitive directions. We suggest there is now a need for further empirical consideration of the extent to which zooplankton e changes with phytoplankton abundance, specifically focusing on the shape of this response, and then for continued assessment of the impact of variable e on model dynamics. [Copyright &y& Elsevier]

Abstract: Budburst date and shoot elongation were measured in two mature Mediterranean evergreen oaks (Quercus suber and Quercus ilex) and their relationships with meteorological and tree water status (predawn leaf water potential) data were analysed. Experimental work took place at two sites: Mitra 2 – Southern Portugal (2002–2003) and Lezirias – Central Portugal (2007–2010). Quercus suber phenology was studied at both sites whereas Q. ilex was only studied at Mitra 2. Quercus suber budburst date occurred at a photoperiod around 13.8h (± 0.26) – late April/early May – and was highly related to the average daily temperature in the period 25 March – budburst date (ca. 1.5months prior to budburst), irrespective of site location. In that period, budburst date was much more dependent on average maximum than average minimum daily temperature. Base temperature and thermal time for Q. suber were estimated as 6.2°C (within the reported literature values) and 323 degree-days, respectively. Q. ilex budburst occurred about 6weeks earlier than in Q. suber (photoperiod: 12.3h (±0.3)). Relationships of Q. ilex budburst date and temperature were not studied since only 2years of data were available for this species. Q. suber shoot elongation underlying mechanisms were quite different in the two sites. At Mitra 2 (Q. suber and Q. ilex), there was a considerable tree water stress during the dry season which restricted shoot elongation. Shoot growth was resumed later in the wet autumn when tree water status recovered again. At the Lezirias site Q. suber water status was not restrictive. Therefore, shoot elongation was mainly dependent on nutrient availability in top soil, as suggested by the strong and positive relationships between annual shoot growth and long-term cumulative rainfall (2–4months) and short-term average temperature (1month) prior to budburst. Annual shoot elongation at this well-watered site was higher than in Mitra 2, and variability of growth between trees was enhanced after warm, wet springs when shoot elongation was higher. Results obtained are relevant to the carbon balance, productivity and management of evergreen Mediterranean oak woodlands, particularly under the foreseen climate change scenarios. [Copyright &y& Elsevier]

Abstract: Three Isochrysis galbana strains, one I. galbana “substrain”, and one Nannochloropsis sp. strain were grown in nutrient replete conditions at 15, 20, 25, and 30°C. The interactive effect of temperature and isolate on growth rate, cell volume, production, dry weight, protein content, carbohydrate content, and total lipid content was examined. Nannochloropsis sp., growth rate had no relation with temperature; all I. galbana isolates increased linearly with temperature, with no significant differences. Cell volume and dry weight decreased linearly with temperature, with significant isolate and species differences. Biovolume-production did not vary significantly with temperature, but significant isolate and species differences occurred. Although significant temperature isolate interactions existed, no consistent trends in the change of protein, carbohydrate, and lipid with temperature occurred. We indicate a need to consider temperature induced affects in application using microalgae isolates, at various taxonomic levels, as some intraspecific differences were as great as interspecific differences. [ABSTRACT FROM AUTHOR]

Oxyrrhis marina is an important model in ecological studies of free-living protists. Despite this, O. marina has rarely been studied in the environment and no explicit distributional studies exist. Further, phylogenetic data for a small number of isolates indicate that O. marina constitutes two divergent lineages. Here, we quantify phylogenetic variation between 58 globally distributed O. marina isolates using 5.8S – internal transcribed spacer 1 and 2 rDNA (5.8S ITS) and cytochrome c oxidase I (COI) partial sequences. 5.8S ITS and COI phylogenies both partitioned O. marina into four clades, which formed two lineages; mean sequence identity for 5.8S ITS and COI respectively was ∼40 and 90% between these two lineages. Sequence identities for 5.8S ITS/ COI between clades within lineages were 66.3/99.4% (lineage 1: clade 1 vs 2) and 42.3/99.1% (lineage 2: clade 3 vs 4). rDNA mutation rates in O. marina appear to be abnormally high and were not interpreted in a species delineation context. Based on variation in COI sequence and comparisons with other protists, we suggest that O. marina lineages may constitute two species. In a geographic context, evidence of spatial restriction but also extensive overlap between O. marina clades occurred. Further, clade abundances varied considerably: clades 1 and 2 (belonging to one lineage) were abundant and widespread; in contrast, clades 3 and 4 (belonging to the second lineage) were rare and spatially restricted (occurring only in the Mediterranean or in culture collection). There is need for further phylogenetic and taxonomic studies to assess species delineation in O. marina, and for the application of high resolution genetic markers to resolve processes driving genetic diversity in this important model organism. [Copyright &y& Elsevier]

• Development of the heat transfer model of a coated thermal barrier as a fire protection device. • The transfer function in the analytical solution was simplified using a Padé approximant around the origin of the Laplace domain. • Theoretical and experimental testing showed good accuracy of model's predictions for the temperature distribution in the thermal barrier. • Maximum deviations of 14% obtained on the heat source side of the thermal barrier and 8.7% on the opposite side. Fiberglass thin blankets with an aluminium coating are often used for fire protection due to their capacity to withstand extreme incident radiant and convective heat fluxes. This article develops a one-dimensional heat transfer model for predicting the temperature distribution for this coated thermal barrier considering the radiant heat flux from the flame front [ O (10 1) kW / m 2 ] and convective heat fluxes from the heated combustion gases on the front side, and a convective heat transfer on the opposite side. The mathematical model developed uses a Padé Approximant to convert the analytical solution from the Laplace to the Fourier domain. And this approximation is validated numerically through finite differences, and experimentally with an appropriate laboratory experimental setup. The accuracy of the results obtained show a good agreement in both validation schemes. Namely, concerning the laboratory experiments, the heat transfer model captured the barrier's thermal behaviour with maximum absolute deviations of 14% on the heat source side of the thermal barrier and 8.7% on the opposite side. The imperfect thermal contact in the experimental setup was discussed as a possible source of error. [ABSTRACT FROM AUTHOR]

Voltage-gated potassium channels are transmembrane proteins made up of four subunits, each comprising six transmembrane (S1-S6) segments. S1-S4 form the voltage-sensing domain and S5-S6 the pore domain with its central pore. The sensor domain detects membrane depolarization and transmits the signal to the activation gates situated in the pore domain, thereby leading to channel opening. An understanding of the mechanism by which the sensor communicates the signal to the pore requires knowledge of the structure of the interface between the voltage-sensing and pore domains. Toward this end, we have introduced single cysteine mutations into the extracellular end of S4 (positions 356 and 357) in conjunction with a cysteine in S5 (position 418) of the Shaker channel and expressed the mutants in Xenopus oocytes. We then examined the propensity of each pair of engineered cysteines to form a metal bridge or a disulfide bridge, respectively, by examining the effect of Cd[sup 2+] ions and copper phenanthroline on the K[sup +] conductance of a whole oocyte. Both reagents reduced currents through the S357C,E418C double mutant channel, presumably by restricting the movements necessary for coupling the voltage-sensing function to pore opening. This inhibitory effect was seen in the closed state of the channel and with heteromers composed of S357C and E418C single mutant subunits; no effect was seen with homomers of any of the single mutant channels. These data indicate that the extracellular end of S4 lies in close proximity to the extracellular end of the S5 of the neighboring subunit in closed channels. [ABSTRACT FROM AUTHOR]

Objectives: To analyse the current knowledge based on the experimental and the clinical research studies focused on the main fields of cardiopulmonary resuscitation.Data sources: International guidelines and recent review articles. Data collected from the Medline database with the key word: cardiac arrest.Study selection: Research studies published during the last ten years were reviewed. Relevant clinical information was extracted and discussed when it induced changes in guidelines.Data synthesis: Promising improvements on basic and advanced life supports are proposed. Chest compressions prevail over ventilation. Alternatives to classical chest compressions are tested. Ventilatory volume must be reduced from 1000 to approximatively 500 mL for each breath with oxygen. Biphasic waveform defibrillators and automated external defibrillators will be considered as the best devices in the near future. Some non-catecholaminergic vasopressors could reduce the use of epinephrine for advanced cardiac life support. Lidocaine could be replaced by amiodarone as anti-arrhythmic drug of choice. New post-resuscitation therapeutic strategies are evaluated, especially coronary reperfusion when the cause of cardiac arrest is cardiac.Conclusion: Many fields of cardiopulmonary resuscitation are investigated. Some relevant informations are included in the last international guidelines published in 2000, but most of them need complementary studies before other changes could be recommended for routine practice. [Copyright &y& Elsevier]

• Carbon harvested in cork represent less than 1.5% of annual net primary production. • Cork is a very low nutrient demanding tissue compared to leaf canopy. • Trunk water losses following cork stripping are negligible. • Cork stripping induced a 46% decrease on sap flow in a dry year. • Cork harvesting practice should be avoided in severe dry years. Cork is a high value periodical forest product which ensures the economic, social and ecological sustainability of cork oak woodlands. Abiotic and biotic stresses lead to tree decline which is endangering the productivity and sustainability of these ecosystems. It is therefore critical to find and implement management practices that minimize the impact of these stresses. The current study was conducted in a certified evergreen cork oak woodland of central Portugal under Mediterranean climate. The main aims of the study were to assess the effects of cork stripping in tree water and carbon fluxes. Results are based on the monitoring of cork stripped and unstripped (control) trees. The experiment was repeated with different sets of trees during two contrasting summers (2014 and 2015). 2014 was a wet year (924 mm) with a typical summer drought pattern and 2015 a dry year (440 mm) with a 31% reduction in annual average precipitation. In 2015 the experimental site was entirely cork harvested and effects on ecosystem CO 2 fluxes were evaluated. Results showed that the amount of carbon in harvested cork represents less than 1.5% of net primary production on a yearly basis. In addition, cork tissue is very low demanding in nutrients: primary macronutrients content in cork represents approximately 2% of the yearly nutrient needs of leaf canopy. Regardless of the climatic year, trunk water losses following cork stripping amounted to only 2% of canopy transpiration not affecting significantly summer tree water balance. However, cork stripping induced a 46% decrease on sap flow in the dry year suggesting that cork stripping triggered an increase in stomatal closure through an interaction between stripping traumatic effects and soil water scarcity. Although the effects of summer drought on carbon sequestration are more prominent than cork stripping effects, this superimposed stress led to a significant reduction of summer net carbon ecosystem exchange (ca. 32%). Our results suggest that cork stripping detrimental effects can be especially critical in more vulnerable trees growing near their vitality breakdown threshold. Therefore, and concerning cork oak woodland management, the cork stripping practice should be avoided in severe dry years and in the more stress-prone trees. [ABSTRACT FROM AUTHOR]

Development of a pseudoaneurysm of the ascending aorta is an uncommon complication of aortic surgery. Several nonsurgical techniques are available for treatment of ascending aortic pseudoaneurysms (AAPs). This report outlines a single-center retrospective experience with 14 nonsurgical procedures for treatment of AAPs in 10 patients. Modified stent grafts, septal defect occlusion devices, coil embolics, and liquid embolics were deployed by transthoracic and endovascular approaches. Complete stasis of the AAP was achieved in 7 of 10 patients (70%). Mean postprocedural recoveries occurred within 3.5 days. Nonsurgical techniques for repair of AAPs offer a comparatively safe and effective alternative to open surgical repair. [ABSTRACT FROM AUTHOR]

During the last years, poly(ionic liquids) (PILs) have been gaining increased attention as materials for analytical chemistry. This success is due to the fact that PILs synthesis is generally based on the polymerization of ionic liquid monomers (ILMs), and thus some of their remarkable properties are shared with their polymeric form. Consequently, the facile design of task-specific ILMs led to an important platform to design new materials for solid phase microextraction (SPME). In this review, a critical evaluation of the main breakthroughs on the use of PILs as extraction phases for SPME. In particular, this critical review covers from ILMs/PILs synthesis, fiber coating processes, surface modifications (silica and metallic supports), to extraction modes, analytes categories, type of equipment ending with a discussion on limitations and future perspectives. PILs are undoubtedly competing in the frontline as inspiring materials for SPME. [ABSTRACT FROM AUTHOR]

Abstract: We recently showed that the highly organized architecture of the corneal stroma could be reproduced using scaffolds consisting of orthogonally aligned multilayers of collagen fibrils prepared using a high magnetic field. Here we show that such scaffolds permit the reconstruction in vitro of human hemi-corneas (stroma + epithelium), using primary human keratocytes and limbal stem cell derived human keratinocytes. On the surface of these hemi-corneas, a well-differentiated epithelium was formed, as determined both histologically and ultrastructurally and by the expression of characteristic markers. Within the stroma, the keratocytes aligned with the directions of the fibrils in the scaffold and synthesized a new extracellular matrix with typical collagen markers and small, uniform diameter fibrils. Finally, in vivo experiments using a rabbit model showed that these orthogonally oriented multi-layer scaffolds could be used to repair the anterior region of the stroma, leading to re-epithelialization and recovery of both transparency and ultrastructural organization. [ABSTRACT FROM AUTHOR]

Abstract: Dialysis related amyloidosis (DRA) is a progressive and serious complication in patients under long-term hemodialysis and mainly leads to osteo-articular diseases. Although β2-microglobulin (β2-m) is the major structural component of β2-m amyloid fibrils, the initiation of amyloid formation is not clearly understood. Here, we have identified procollagen C-proteinase enhancer-1 (PCPE-1) as a new interacting protein with β2-m by screening a human synovium cDNA library. The interaction of β2-m with full-length PCPE-1 was confirmed by immunoprecipitation, solid-phase binding and pull-down assays. By yeast two-hybrid analysis and pull-down assay, β2-m appeared to interact with PCPE-1 via the NTR (netrin-like) domain and not via the CUB (C1r/C1s, Uegf and BMP-1) domain region. In synovial tissues derived from hemodialysis patients with DRA, β2-m co-localized and formed a complex with PCPE-1. β2-m did not alter the basal activity of bone morphogenetic protein-1/procollagen C-proteinase (BMP-1/PCP) nor BMP-1/PCP activity enhanced by PCPE-1. PCPE-1 did not stimulate β2-m amyloid fibril formation from monomeric β2-m in vitro under acidic and neutral conditions as revealed by thioflavin T fluorescence spectroscopy and electron microscopy. Since PCPE-1 is abundantly expressed in connective tissues rich in type I collagen, it may be involved in the initial accumulation of β2-m in selected tissues such as tendon, synovium and bone. Furthermore, since such preferential deposition of β2-m may be linked to subsequent β2-m amyloid fibril formation, the disruption of the interaction between β2-m and PCPE-1 may prevent β2-m amyloid fibril formation and therefore PCPE-1 could be a new target for the treatment of DRA. [Copyright &y& Elsevier]

Abstract: In this review paper, state-of-the-art observational and numerical modeling methods for small scale turbulence and mixing with applications to coastal oceans are presented in one context. Unresolved dynamics and remaining problems of field observations and numerical simulations are reviewed on the basis of the approach that modern process-oriented studies should be based on both observations and models. First of all, the basic dynamics of surface and bottom boundary layers as well as intermediate stratified regimes including the interaction of turbulence and internal waves are briefly discussed. Then, an overview is given on just established or recently emerging mechanical, acoustic and optical observational techniques. Microstructure shear probes although developed already in the 1970s have only recently become reliable commercial products. Specifically under surface waves turbulence measurements are difficult due to the necessary decomposition of waves and turbulence. The methods to apply Acoustic Doppler Current Profilers (ADCPs) for estimations of Reynolds stresses, turbulence kinetic energy and dissipation rates are under further development. Finally, applications of well-established turbulence resolving particle image velocimetry (PIV) to the dynamics of the bottom boundary layer are presented. As counterpart to the field methods the state-of-the-art in numerical modeling in coastal seas is presented. This includes the application of the Large Eddy Simulation (LES) method to shallow water Langmuir Circulation (LC) and to stratified flow over a topographic obstacle. Furthermore, statistical turbulence closure methods as well as empirical turbulence parameterizations and their applicability to coastal ocean turbulence and mixing are discussed. Specific problems related to the combined wave–current bottom boundary layer are discussed. Finally, two coastal modeling sensitivity studies are presented as applications, a two-dimensional study of upwelling and downwelling and a three-dimensional study for a marginal sea scenario (Baltic Sea). It is concluded that the discussed methods need further refinements specifically to account for the complex dynamics associated with the presence of surface and internal waves. [Copyright &y& Elsevier]

Abstract: The creation of 3D scaffolds that mimic the structure of physiological tissue required for normal cell function is a major bioengineering challenge. For corneal stroma reconstruction this necessitates the creation of a stroma-like scaffold consisting of a stack of orthogonally disposed sheets of aligned collagen fibrils. This study demonstrates that such a scaffold can be built up using magnetic alignment. By allowing neutralized acid-soluble type I collagen to gel in a horizontal magnetic field (7T) and by combining a series of gelation–rotation–gelation cycles, a scaffold of orthogonal lamellae composed of aligned collagen fibrils has been formed. Although initially dilute, the gels can be concentrated without noticeable loss in orientation. The gels are translucent but their transparency can be greatly improved by the addition of proteoglycans to the gel-forming solution. Keratocytes align by contact guidance along the direction of collagen fibrils and respect the orthogonal design of the collagen template as they penetrate into the bulk of the 3D matrix. The scaffold is a significant step towards the creation of a corneal substitute with properties resembling those of native corneal stroma. [Copyright &y& Elsevier]

α-Synuclein has been linked to amyloidogenesis in Parkinson''s disease and other neurodegenerative disorders. We have previously shown that a peptide comprising residues 68–78 of α-synuclein is the minimum fragment that, like α-synuclein itself, forms amyloid fibrils and exhibits toxicity towards cells in culture. Hughes et al. [J. Biol. Chem. 275 (2000) 25109] showed that an N-methylated derivative of Aβ(25–35) inhibited the formation of fibrils by Aβ(25–35) and reduced its toxicity. We have now extended this concept to an amyloidogenic α-synuclein-based peptide. α-Synuclein(68–78), N-methylated at G1y73, was compared to non-methylated peptide. Whereas α-synuclein(68–78) formed fibrils and was toxic to cells, the N-methylated analogue had neither of these properties. Moreover, an equimolar mixture of the non-methylated and methylated peptides formed very few fibrils and toxicity was markedly reduced. [Copyright &y& Elsevier]

α-Helical coiled coils are widely occurring protein oligomerization motifs. Here we show that most members of the collagen superfamily contain short, repeating heptad sequences typical of coiled coils. Such sequences are found at the N-terminal ends of the C-propeptide domains in all fibrillar procollagens. When fused C-terminal to a reporter molecule containing a collagen-like sequence that does not spontaneously trimerize, the Cpropeptide heptad repeats induced trimerization. C-terminal heptad repeats were also found in the oligomerization domains of the multiplexins (collagens XV and XVIII). N-terminal heptad repeats are known to drive trimerization in transmembrane collagens, whereas fibril-associated collagens with interrupted triple helices, as well as collagens VII, XIII, XXIII, and XXV, were found to contain heptad repeats between collagen domains. Finally, heptad repeats were found in the von Willebrand factor A domains known to be involved in trimerization of collagen VI, as well as in collagen VII. These observations suggest that coiled-coil oligomerization domains are widely used in the assembly of collagens and collagen-like proteins. [ABSTRACT FROM AUTHOR]

Studies procollagen C-proteinase enhancer (PCPE), an extracellular matrix glycoprotein. Low-resolution structure determination showing that PCPE is an elongated multidomain glycoprotein; Ability to stimulate the action of tolloid metalloproteinasse; Function of PCPE.