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Search Results: 1 - 10 of 191314 matches for " An D. Billiau "
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The Dark Side of EGFP: Defective Polyubiquitination
Mathijs Baens, Heidi Noels, Vicky Broeckx, Sofie Hagens, Sabine Fevery, An D. Billiau, Hugo Vankelecom, Peter Marynen
PLOS ONE , 2006, DOI: 10.1371/journal.pone.0000054
Abstract: Enhanced Green Fluorescent Protein (EGFP) is the most commonly used live cell reporter despite a number of conflicting reports that it can affect cell physiology. Thus far, the precise mechanism of GFP-associated defects remained unclear. Here we demonstrate that EGFP and EGFP fusion proteins inhibit polyubiquitination, a posttranslational modification that controls a wide variety of cellular processes, like activation of kinase signalling or protein degradation by the proteasome. As a consequence, the NF-κB and JNK signalling pathways are less responsive to activation, and the stability of the p53 tumour suppressor is enhanced in cell lines and in vivo. In view of the emerging role of polyubiquitination in the regulation of numerous cellular processes, the use of EGFP as a live cell reporter should be carefully considered.
Solvent effect modelling of isocyanuric products synthesis by chemometric methods
Jean-Louis Havet,Myriam Billiau-Loreau,Catherine Porte,Alain Delacroix
Journal of Analytical Methods in Chemistry , 2002, DOI: 10.1155/s1463924602000159
Abstract: Chemometric tools were used to generate the modelling of solvent e¡ects on the N-alkylation of an isocyanuric acid salt. The method proceeded from a central composite design applied on the Carlson solvent classification using principal components analysis. The selectivity of the reaction was studied from the production of different substituted isocyanuric derivatives. Response graphs were obtained for each compound and used to devise a strategy for solvent selection. The prediction models were validated and used to search for the best selectivity for the reaction system. The solvent most often selected as the best for the reaction is the N,N-dimethylformamide.
Defective CD4+CD25+ regulatory T cell functioning in collagen-induced arthritis: an important factor in pathogenesis, counter-regulated by endogenous IFN-γ
Hilde Kelchtermans, Bert De Klerck, Tania Mitera, Maarten Van Balen, Dominique Bullens, Alfons Billiau, Georges Leclercq, Patrick Matthys
Arthritis Research & Therapy , 2005, DOI: 10.1186/ar1500
Abstract: The adaptive immune system uses various potent effector mechanisms for the elimination of foreign pathogens. Because these mechanisms are potentially damaging to the host, an essential feature of the immune system is its ability to distinguish self from non-self antigens and to develop tolerance to the former. With regard to T cell tolerance, the immune system has evolved several strategies. Most autoreactive T cells are eliminated during (primary) maturation in the thymus, a process described as negative selection, resulting in central T cell tolerance. Autoreactive T cells that escape negative selection will nevertheless be prevented from being activated as they are confronted with auto-antigen in the periphery. Several mechanisms have been proposed to account for this peripheral tolerance. One of those is suppression by a subset of T cells that express both CD4 and CD25. Evidence for the important role of these cells is overwhelming [1]. For example, when CD4+ T cells isolated from peripheral lymphoid tissues of normal mice are depleted of CD4+CD25+ T cells and injected into nu/nu mice, the recipients develop a high incidence of organ-specific autoimmune disease [2]. Co-transfer of the CD4+CD25+ population prevents the induction of disease. CD4+CD25- and CD4+CD25+ T cells are therefore often designated as, respectively, Teff and Treg cells. CD4+CD25+ Treg cells are generated in the thymus. Their development is directed by relatively high-avidity interactions between the TCR and self-peptide ligands [3-5]. The CD4+CD25+ Treg cell population constitutes 5 to 10% of the mature CD4+ cell population in the adult thymus and the peripheral lymphoid tissue and blood.In vitro, CD4+CD25+ Treg cells inhibit polyclonal T cell activation [6,7]. The suppression is mediated by a cytokine-independent, cell contact-dependent mechanism that requires activation of the CD4+CD25+ cells via the TCR with specific antigen [8]. However, once stimulated, they are competent to suppress in
Enhanced osteoclast development in collagen-induced arthritis in interferon-γ receptor knock-out mice as related to increased splenic CD11b+ myelopoiesis
Bert De Klerck, Isabelle Carpentier, Rik J Lories, Yvette Habraken, Jacques Piette, Geert Carmeliet, Rudi Beyaert, Alfons Billiau, Patrick Matthys
Arthritis Research & Therapy , 2004, DOI: 10.1186/ar1167
Abstract: Collagen-induced arthritis (CIA) is a well-characterised experimental model for rheumatoid arthritis in humans. One common aspect of the two conditions is the occurrence of bone destruction in the joints caused by osteoclast activation in the synovium. Mice lacking a functional interferon-γ (IFN-γ) receptor (interferon-γ receptor knockout [IFN-γR KO] mice) are more susceptible to CIA than wild-type mice [1,2]: the median day of disease onset is reduced from 43 to 21 days and both the severity and the cumulative incidence of arthritis are higher. Similarly, in wild-type mice, disease onset is accelerated and scores of arthritis are increased by treatment with neutralising monoclonal antibodies against IFN-γ [2]. Accelerated disease onset in both experimental settings is associated with an increased expansion of CD11b+ myeloid cells in the spleen [3]. In this study we investigated the possibility that these CD11b+ cells can differentiate into osteoclasts and therefore that their expansion in IFN-γR KO mice can in part account for the higher susceptibility of such mice to CIA. In addition we analysed the molecular signals for osteoclastogenesis in IFN-γR KO and wild-type mice.Osteoclasts and osteoblasts are essential for bone homeostasis and remodelling, a process that continues throughout life [4-6]. In a healthy organism the activities of both cell types are in balance. Generalised imbalance causes either osteoporosis or osteopetrosis. Localised impairment of the equilibrium can cause local damage of the bone tissue. This is considered to be a major pathogenic process in rheumatoid arthritis and similarly in CIA [7,8], as articular lesions evolve in parallel with increased numbers of osteoclasts in the inflamed synovium [8]. Osteoclast precursors belong to the monocyte/macrophage lineage [5,9,10]. They can be recruited from the bone marrow and, in mice, from the spleen [11]. Their differentiation into active osteoclasts is regulated by several cytokines: receptor act
Pro-inflammatory properties of stromal cell-derived factor-1 (CXCL12) in collagen-induced arthritis
Bert De Klerck, Lies Geboes, Sigrid Hatse, Hilde Kelchtermans, Yves Meyvis, Kurt Vermeire, Gary Bridger, Alfons Billiau, Dominique Schols, Patrick Matthys
Arthritis Research & Therapy , 2005, DOI: 10.1186/ar1806
Abstract: Among chemokines, CXCL12 (formerly stromal cell-derived factor 1) is unique in that it binds to one single chemokine receptor, CXCR4, which itself is recognized by no other chemokines [1-3]. CXCL12 is produced physiologically in various tissues and its receptor CXCR4 is also expressed on various haematopoietic and non-haematopoietic cells. By binding to heparan sulphate proteoglycans, secreted CXCL12 can adhere to certain cells such as bone marrow stromal cells. Through this mechanism, CXCL12-CXCR4 interaction plays an important role in homing of myeloid and lymphoid cells to specific sites in bone marrow or secondary lymphoid organs. CXCR4 also acts as an important co-receptor for HIV entry into CD4+ human lymphocytes [4]. Like other members of the chemokine family, CXCL12 may play a role in inflammatory diseases. Specifically, there is increasing evidence that CXCL12 plays a crucial role in patients with rheumatoid arthritis (RA). In RA patients, abnormally high concentrations of CXCL12 in synovial fluid and overexpression of CXCL12 in synovial cells have been found [5-8]. Moreover, CXCR4+ leukocytes in synovia were found to be significantly more abundant [7]. Evidence also points to a role for CXCL12 in positioning CXCR4+ T and B cells to distinct synovial microdomains as well as in retaining these cells within the inflamed synovial tissue [9]. CXCL12 induces migration of monocytes into human arthritic synovium transplanted into severe combined immunodeficiency (SCID) mice [10]. In addition to exerting these effects on cell migration, CXCL12 also induces angiogenesis during RA development [8] and stimulates chondrocytes to release matrix metalloprotease 3 (MMP3), a matrix-degrading enzyme involved in cartilage destruction [5].Availability of specific inhibitors of the CXCL12-CXCR4 interaction has allowed the demonstration of the involvement of CXCL12 in experimental animal diseases. One such inhibitor is the bicyclam drug AMD3100, originally discovered as an anti
Electrical Conductivity of Collapsed Multilayer Graphene Tubes  [PDF]
D. Mendoza
World Journal of Nano Science and Engineering (WJNSE) , 2012, DOI: 10.4236/wjnse.2012.22009
Abstract: Synthesis of multilayer graphene on copper wires by a chemical vapor deposition method is reported. After copper etching, the multilayer tube collapses forming stripes of graphitic films, their electrical conductance as a function of temperature indicate a semiconductor-like behavior. Using the multilayer graphene stripes, a cross junction is built and owing to its electrical behavior we propose that a tunneling process exists in the device.
Porous Carbon Grown by Chemical Vapor Deposition on Copper Substrates  [PDF]
D. Mendoza
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.38003
Abstract: Amorphous porous carbon was synthesized by chemical vapor deposition on copper substrates. The average size of the pores is around 1.2 microns with some small pores decorating the big ones. Lamellar samples of this carbonaceous material can be separated from the copper support and may be useful as electrode due to its low electrical resistivity of the order of 0.4 Ωcm.
Application of Enzyme Extracted from Aloe vera Plant in Chemical Pretreatment of Cotton Knitted Textile to Reduce Pollution Load  [PDF]
D. Jothi
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33B007

Nowadays, highly alkaline chemicals like caustic soda, soda ash, silicate, acetic acid and soaping agents are used for scouring to remove the non-cellulosic impurities from the cotton. Using 30 - 40 gm/Kg on weight of the fabric results in destruction of cotton structure. Intensive rinsing and more acid is needed for reutilization of cotton, which enlarges the volume of effluent. Furthermore, these hazards chemicals result in increase in COD, BOD and TDS in waste water. These chemicals also attack the cellulose leading to heavy strength loss and weight loss in the fabric. The net result is low quality control and polluted environment with high usage of energy, time, chemical and water. Aloe vera presents the finest commercial opportunity in various industrial sectors among the various plants. Also, most of the countries are gifted with the unique geographical features that are essential for cultivation of Aloe vera. Yet, none of the country has realized and reaped the full potential of such plants in various industrial applications. The reason is simple: lack of the requisite expertise in extraction of various enzymes present in aloe plant. Fortunately, the technology is now accessible to make use of enzyme in textile application. In this research an attempt has been made to make use of lipase enzyme extracted from aloe plant in textile chemical pre- treatment process. In the present research work, an attempt was made to develop bio scouring of 100% cotton knitted fabric with lipase enzyme extracted from Aloe deberena plant at various concentration (1%, 2% and 3%) at various temperature (40?C, 60?C and 70?C) for a period of 30 minutes, 60 minutes and 90 minutes. The properties of bio scoured fabrics are compared with these of conventional scoured one. Encouraging results in terms of dye uptake, dye levelness, wash fastness, light fastness and rubbing fastness are obtained in case of bio scouring fabric dyed with dark reactive colors. Further, it reduces volume of effluent as well as COD, TDS and pH. It saves a substantial thermal energy 50% and electrical energy 40%. Bio scouring waste water has 40% - 50% less COD and 60% less TDS as compared to conventional scouring waste water.

Hyporheic Zone Hydrochemistry of the Mine-Polluted River  [PDF]
D. Ciszewski
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.310008

Intensity of stream waters mixing with groundwaters and lateral extent of these processes in the hyporheic zone were investigated in a near-bank sandbar and an adjacent floodplain through the comparison of groundwaters and stream water chemistry of the Bia?a Przemsza River in southern Poland. The stream waters were polluted by the discharge of mine waters from “Boles?aw” lead and zinc mine. The investigated waters were several times more mineralized than the natural spring waters of the river valley. The concentration of: potassium, sodium, and the pH, as well as cadmium, lead, and zinc decreased in the hyporheic zone towards the stream bank, whereas conductance, calcium, magnesium, sulphates, as well as silica contents were the highest on the floodplain, diminishing towards the stream. The changes observed in the chemical composition of groundwaters were apparent in mixing stream waters below the depth of 2 m with shallow groundwaters draining the valley slope. Hyporheic mixing also takes place in the 10-meter-wide, marginal zone of the sandbar, whereas in the 5-meter-wide stream-side zone of the sandbar groundwaters represent weakly transformed stream water.

Fractional Topological Insulators—A Bosonization Approach  [PDF]
D. Schmeltzer
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.71012
Abstract: A metallic disk with strong spin orbit interaction is investigated. The finite disk geometry introduces a confining potential. Due to the strong spin-orbit interaction and confining potential the metal disk is described by an effective one-dimensional model with a harmonic potential. The harmonic potential gives rise to classical turning points. As a result, open boundary conditions must be used. We bosonize the model and obtain chiral Bosons for each spin on the edge of the disk. When the filling fraction is reduced to \"\" the electron-electron interactions are studied by using the Jordan Wigner phase for composite fermions which give rise to a Luttinger liquid. When the metallic disk is in the proximity with a superconductor, a Fractional Topological Insulator is obtained. An experimental realization is proposed. We show that by tunning the chemical potential we control the classical turning points for which a Fractional Topological Insulator is realized.
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