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Ixodes ricinus Tick Lipocalins: Identification, Cloning, Phylogenetic Analysis and Biochemical Characterization
Jér?me Beaufays, Beno?t Adam, Yves Decrem, Pierre-Paul Prév?t, Sébastien Santini, Robert Brasseur, Michel Brossard, Laurence Lins, Luc Vanhamme, Edmond Godfroid
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003941
Abstract: Background During their blood meal, ticks secrete a wide variety of proteins that interfere with their host's defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response. Methodology/Principal Findings Screening a cDNA library in association with RT-PCR and RACE methodologies allowed us to identify 14 new lipocalin genes in the salivary glands of the Ixodes ricinus hard tick. A computational in-depth structural analysis confirmed that LIRs belong to the lipocalin family. These proteins were called LIR for “Lipocalin from I. ricinus” and numbered from 1 to 14 (LIR1 to LIR14). According to their percentage identity/similarity, LIR proteins may be assigned to 6 distinct phylogenetic groups. The mature proteins have calculated pM and pI varying from 21.8 kDa to 37.2 kDa and from 4.45 to 9.57 respectively. In a western blot analysis, all recombinant LIRs appeared as a series of thin bands at 50–70 kDa, suggesting extensive glycosylation, which was experimentally confirmed by treatment with N-glycosidase F. In addition, the in vivo expression analysis of LIRs in I. ricinus, examined by RT-PCR, showed homogeneous expression profiles for certain phylogenetic groups and relatively heterogeneous profiles for other groups. Finally, we demonstrated that LIR6 codes for a protein that specifically binds leukotriene B4. Conclusions/Significance This work confirms that, regarding their biochemical properties, expression profile, and sequence signature, lipocalins in Ixodes hard tick genus, and more specifically in the Ixodes ricinus species, are segregated into distinct phylogenetic groups suggesting potential distinct function. This was particularly demonstrated by the ability of LIR6 to scavenge leukotriene B4. The other LIRs did not bind any of the ligands tested, such as 5-hydroxytryptamine, ADP, norepinephrine, platelet activating factor, prostaglandins D2 and E2, and finally leukotrienes B4 and C4.
Variability and Action Mechanism of a Family of Anticomplement Proteins in Ixodes ricinus
Bernard Couvreur, Jér?me Beaufays, Cédric Charon, Kathia Lahaye, Fran?ois Gensale, Valérie Denis, Beno?t Charloteaux, Yves Decrem, Pierre-Paul Prév?t, Michel Brossard, Luc Vanhamme, Edmond Godfroid
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0001400
Abstract: Background Ticks are blood feeding arachnids that characteristically take a long blood meal. They must therefore counteract host defence mechanisms such as hemostasis, inflammation and the immune response. This is achieved by expressing batteries of salivary proteins coded by multigene families. Methodology/Principal Findings We report the in-depth analysis of a tick multigene family and describe five new anticomplement proteins in Ixodes ricinus. Compared to previously described Ixodes anticomplement proteins, these segregated into a new phylogenetic group or subfamily. These proteins have a novel action mechanism as they specifically bind to properdin, leading to the inhibition of C3 convertase and the alternative complement pathway. An excess of non-synonymous over synonymous changes indicated that coding sequences had undergone diversifying selection. Diversification was not associated with structural, biochemical or functional diversity, adaptation to host species or stage specificity but rather to differences in antigenicity. Conclusions/Significance Anticomplement proteins from I. ricinus are the first inhibitors that specifically target a positive regulator of complement, properdin. They may provide new tools for the investigation of role of properdin in physiological and pathophysiological mechanisms. They may also be useful in disorders affecting the alternative complement pathway. Looking for and detecting the different selection pressures involved will help in understanding the evolution of multigene families and hematophagy in arthropods.
Ir-LBP, an Ixodes ricinus Tick Salivary LTB4-Binding Lipocalin, Interferes with Host Neutrophil Function
Jér?me Beaufays, Beno?t Adam, Catherine Menten-Dedoyart, Laurence Fievez, Amélie Grosjean, Yves Decrem, Pierre-Paul Prév?t, Sébastien Santini, Robert Brasseur, Michel Brossard, Michel Vanhaeverbeek, Fabrice Bureau, Ernst Heinen, Laurence Lins, Luc Vanhamme, Edmond Godfroid
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003987
Abstract: Background During their blood meal, ticks secrete a wide variety of proteins that can interfere with their host's defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response. Methodology/Principal Findings We previously identified 14 new lipocalin genes in the tick Ixodes ricinus. One of them codes for a protein that specifically binds leukotriene B4 with a very high affinity (Kd: ±1 nM), similar to that of the neutrophil transmembrane receptor BLT1. By in silico approaches, we modeled the 3D structure of the protein and the binding of LTB4 into the ligand pocket. This protein, called Ir-LBP, inhibits neutrophil chemotaxis in vitro and delays LTB4-induced apoptosis. Ir-LBP also inhibits the host inflammatory response in vivo by decreasing the number and activation of neutrophils located at the tick bite site. Thus, Ir-LBP participates in the tick's ability to interfere with proper neutrophil function in inflammation. Conclusions/Significance These elements suggest that Ir-LBP is a “scavenger” of LTB4, which, in combination with other factors, such as histamine-binding proteins or proteins inhibiting the classical or alternative complement pathways, permits the tick to properly manage its blood meal. Moreover, with regard to its properties, Ir-LBP could possibly be used as a therapeutic tool for illnesses associated with an increased LTB4 production.
H2 and CH4 Sorption on Cu-BTC Metal Organic Frameworks at Pressures up to 15 MPa and Temperatures between 273 and 318 K  [PDF]
Yves Gensterblum
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.12004
Abstract: Sorption isotherms of methane and hydrogen on Cu3(BTC)2 have been measured in the temperature range from 273 to 318 K and at pressures up to 15 MPa. H2 excess sorption capacities of the Cu3(BTC)2 amounted to 3.9 mg/g at 14 MPa. Promising maximum CH4 excess sorption capacities on the same sample were reached at approximately 5 MPa. They amounted to 101, 100, 92 and 80 mg/g at 273, 278, 293 and 318 K, respectively. The sorbed phase density was essestially the same for all temperatures and amounted to ~600 kg/m3. Structural changes of the Cu3(BTC)2 samples after thermal activation and treatment with high pressure H2 and CH4 were tested. It was found that the initial micropore structure has virtually disappeared as evidenced by a decrease of the Langmuir specific surface area by a factor ~3 and CO2 micropore volume by a factor of ~4 for H2 and ~3 for CH4. This is in line with an increase in the average pore diameter from initially 9.2 to 15.7 for H2 and 12.8 for CH4.
Minkowskian Solution of General Relativity with Cosmological Constant and the Accelerating Universe  [PDF]
Yves Pierseaux
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.516172
Abstract: A Minkowskian solution of the equation of General Relativity (as written by Einstein in 1915) is trivial because it simply means that both members of the equation are equal to zero. However, if alternatively, one considers the complete equation with a non-zero constant Λ (Einstein 1917), a Minkowskian solution is no longer trivial because it amounts to impose a constraint on the right hand side of the equation (i.e. a non-null stress-energy tensor). If furthermore one identifies (as usual) this tensor to the one of a perfect fluid, one finds that this fluid has a positive energy density and a negative pressure that depend on the three constants of the equation (i.e. gravitational constant G, cosmological constant Λ and velocity of light c). When doing that (§1), one has to consider the “Minkowskian Vacuum” as a physical object of GR (an enigmatic non-baryonic Minkowskian fluid). Can one build a model of this object on the basis of a dynamical equilibrium between the effective gravitational attraction due to the positive energy density versus the negative pressure repulsion? We propose to study such a model, where the (enigmatic) fluid is assumed to exist only in a limited sphere whose surface acts like a “test body” sensitive to the gravitational field created by the fluid. No static equilibrium exists, but a pseudoNewtonian “dynamical equilibrium” (§2) can be reached if the pseudoEuclidean fluid is in state of expansion. Up to there, we have simply constructed a model of an “abstract Universe” (i.e. the limited sphere: There is no fluid outside this sphere!) that gives to a (purely mathematical) constant Λ a concrete physical meaning. We discover finally that our expanding fluid has not only dynamical (gravitational) properties (§3) but also optical properties that are connected with Doppler Redshift (§4). Remembering that recent observations in Cosmology indicate that the “real Universe” seems to be “Flat” and in “Accelerated Expansion”; remembering also (after all) that the archetypal Flat Universe is simply a Minkowskian Universe, we logically wonder if the unexpected Minkowskian global solution, could not be also a significant cosmological model (conclusion).
PAPR Reduction Scheme with SOCP for MIMO-OFDM Systems  [PDF]
Basel RIHAWI, Yves LOUET
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2008, DOI: 10.4236/ijcns.2008.11005
Abstract: Combination of multiple-input multiple-output (MIMO) with orthogonal frequency division multiplexing (OFDM) has become a promising candidate for high performance wireless communications. However one major disadvantage of MIMO-OFDM systems lies in a prohibitively large peak-to-average power ratio (PAPR) of the transmitted signal on each antenna. In this paper we extend from SISO to MIMO systems a method based on allocating dedicated subcarriers for PAPR mitigation. These subcarriers are located on unused subcarriers of OFDM spectrum under the assumption they all fall under the power mask. This is originally implemented with a SOCP optimization algorithm applied before space time coding scheme. This jointly mitigates PAPR on each MIMO branch scheme. This approach does not degrade the bit-error-rate (BER) and the data bit rate and no side information (SI) transmission is required. Simulation results are presented in the IEEE 802.16 WiMAX standard contexts: an Alamouti space time code with two transmitted antennas and 256 OFDM subcarriers are considered where 56 of which are unused and allocated for PAPR reduction. PAPR gains up to 7dB are obtained depending on mean power increase limitation. Moreover, with a spectrum mask constraint, this method is standard compliant.
Contribution of Topographically Explicit Descriptors of Landscape Measures for Application in the Vector Data Environment  [PDF]
Auda Yves, Jomaa Ihab
Journal of Geographic Information System (JGIS) , 2010, DOI: 10.4236/jgis.2010.23023
Abstract: Digital terrain models (DTMs) are not commonly used to integrate for landscape spatial analysis. Two dimensional patchcorridormatrix models are prototypes in landscape spatial ecology analysis. Previous studies have motivated ecologists to integrate terrain models in landscape analysis through 1) adjusting areas and distance calculations prior computing landscape indices; 2) designing new indices to capture topography and 3) searching the possible relationship between topographic characteristics and vegetation patterns. This study presents new indices called Relative number of Topographic Faces (RTF) and Simplicity of topographic Faces (STF) that can be easily computed in a GIS environment, capturing topographical features of landscapes. Digital terrain model was first prepared and topographic units were extracted and installed in computing the suggested indices. Mountainous and rugged topography in Lebanon was chosen on a forested landscape for the purpose of this study. The indices were useful in monitoring changes of topographic features on patch and landscape level. Both indices are ecologically useful if integrated in landscape pattern analysis, especially in areas of rugged terrains.
Muscle: a source of progenitor cells for bone fracture healing
Yves Henrotin
BMC Medicine , 2011, DOI: 10.1186/1741-7015-9-136
Abstract: Please see related article: http://www.biomedcentral.com/1471-2474/12/288 webciteThere are millions of fractures each year the world over, generated by traumatic injury. According to the force of the impact, fractures are closed with a limited angle of dislocation, or open with a serious displacement of the broken bone extremities inducing severe injuries of the surrounding tissues (muscles, blood vessels, skin, nerves). While immobilization and surgery may facilitate healing, a fracture ultimately heals through physiological processes in 6 to 8 weeks. Bone repair is dependent on the presence of osteocompetent progenitors that are able to differentiate and generate new bone. Progenitors coming from the periosteum and the bone marrow compartment play a pivotal role. However, there are many circumstances that limit the access of these primary osteoprogenitors, for example, damage to the periosteum, debridement to prevent infection and internal fixation. These circumstances occur in high-energy traumatic open fractures, which often leads to 'non-union' (pseudarthrosis or failed fracture) of the broken bone extremities. In the case of a non-union, a fracture does not heal. The prevalence of non-union of closed tibial shaft fracture is 2.5% and increases 5.7-fold for open fractures with gross contamination and extensive soft damage [1]. Other reasons for a non-union fracture may include complicated, multisegmental fractures (severe comminution), open fractures, fractures associated with tumors (pathologic fractures), infection, insufficient fracture immobilization (fixation), inadequate blood supply, poor nutrition and chronic disease state (diabetes, renal failure, metabolic bone disease). These fractures may lead to severe secondary complications and disability, and result in a high socioeconomical impact. Current treatment requires surgery techniques, but a high percentage of failure is associated with this.Most non-union fractures require open surgery to realign the
Pesquisar e formar: repensar o lugar e a fun??o da prática de ensino
Lenoir, Yves;
Educa??o & Sociedade , 2006, DOI: 10.1590/S0101-73302006000400011
Abstract: the present paper deals with the links between research, education and practice. after having reminded the criticism to which research in education has been subjected, it points out the specificity of scientific research, its characteristics, its structural components and its functions as a cognitive objectivation process. the issue of distinguishing between methods and methodology is then examined, so as to enhance the need to resort to combined methods to analyse the teaching practices, and to stress the necessity of considering the scientific approach from a four-pole-structure. finally, the relationships between research and practices are explored in regard to teacher education.
Os ingredientes da competência: Um exercício necessário para uma quest?o insolúvel
Schwartz, Yves;
Educa??o & Sociedade , 1998, DOI: 10.1590/S0101-73301998000400004
Abstract: for a decade now, technical changes in management and economy have driven people in charge of projects and companies to gradually substitute the word "competences" for the word "qualification" to cope with the task of adapting people to jobs and objectives, and to seek procedures or formats to assess such competences. but, right though we may be in putting forward the issue - even beyond the current economic situation - such a quest for out-of-context, homogeneous and easy-to-codify procedures or diagrams is inconsistent with the numerous levels or elements to be put together in any working activity. there are at least three quite different sides to a working activity: the extent to which conceptualizable knowledge can be reached, the extent to which the very historical aspects of a situation can be understood, and the clash of values with which any individual is confronted in a given working environment. hence the basic heterogeneity of the components of competency, of the dynamic relationship between these components - which can never be actually foreseen - and thus of the research to be done on the various formats of assessment suited to the variety of those components.
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