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Dimerization
Kinds of Dimerization Terms modified by Dimerization Selected AbstractsSlamming the DOR on chemokine receptor signaling: Heterodimerization silences ligand-occupied CXCR4 and ,-opioid receptorsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2008Dale Hereld Abstract Dimerization has emerged as a common mechanism for regulating the function of G protein-coupled receptors (GPCR). Among these are chemokine receptors, which detect various chemokines and regulate a range of physiological process, including immune cell trafficking, cancer cell migration, and neuronal patterning. Homo- and heterodimerization in response to chemokine binding has been shown to be required for the initiation or alteration of signaling by a number of chemokine receptors. In this issue of the European Journal of Immunology, a new study indicates that the formation of heterodimers of chemokine receptor CXCR4 and the ,-opioid receptor (DOR) prevents each of them from actively signaling, suggesting a novel mechanism for silencing GPCR function. See accompanying article: http://dx.doi.org/10.1002/eji200737630 [source] "Tail,Tail Dimerization" of Ferrocene Amino Acid DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2010Daniel Siebler Abstract Acid anhydrides of N-protected 1,-aminoferrocene-1-carboxylic acid (Fca) have been prepared and spectroscopically characterized (protection group Boc, Fmoc, Ac; 4a,4c). The structure of the Boc-derivative 4a has been determined by single-crystal X-ray crystallography. An intramolecular N,H···O hydrogen bond involving the carbamate units results in a ring structure containing the two ferrocene units, the anhydride moiety, and the hydrogen bond. In the crystal, the individual molecules are connected by intermolecular N,H···O hydrogen bonds of the carbamate unit. Experimental and theoretical studies suggest that the ring motif is also a dominant species in solution. Electronic communication across the anhydride moiety is found to be very weak as judged from electrochemical, spectroscopic, and theoretical experiments. [source] Mono(aryloxido)Titanium(IV) Complexes and Their Application in the Selective Dimerization of EthyleneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2009Jean-Benoit Cazaux Abstract We report on the synthesis of mono(aryloxido)titanium(IV) complexes of general formula {Ti[O(o -R)Ar]X3}, with X = OiPr, ArO = 2- tert -butyl-4-methylphenoxy and R = CMe3 (2a), CMe2Ph (2b) and CH2NMe2 (2c). Attempts to reach pure mono(aryloxido) complexes when R = CH2NMe(CH2Ph) (2d) or CH2N(CH2Ph)2 (2e) were unsuccessful. When R = CH2OMe, the analogous mononuclear complex was not obtained, and instead, a dinuclear complex [(2- tert -butyl-4-methyl-6-methoxymethylphenoxy) TiCl(OiPr)(,2 -OiPr)2TiCl(OiPr)2] (3) was formed. Complexes 2b and 3 were characterized by single-crystal X-ray diffraction. The former contains a tetrahedrally coordinated TiIV centre, whereas in the latter the aryloxido ligand behaves as a chelating,bridging ligand between the two, chemically very different metal centres that form two face-sharing octahedra. Different synthetic approaches starting from [Ti(OiPr)4] or [TiCl(OiPr)3] were evaluated and are discussed. The hemilabile behaviour of the aryloxido ligand resulting from reversible coordination of its side arm was studied by variable-temperature 1H NMR spectroscopy for 2c (R = CH2NMe2). Complexes 2a,d were contacted with ethylene and AlEt3 as cocatalyst. When activated with AlEt3 (3 equiv.) at 20 bar and 60 °C, complex 2c exhibits interesting activity (2100 g/gTi/h) for the selective dimerization of ethylene to 1-butene (92,% C4=; 99+% C4=1). Noticeable differences in catalyst activity were observed when the R group was modified. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Structural and Electrochemical Studies of Dimerization and Rotational Isomerization in Multi-Iron SilicotungstatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2005Travis M. Anderson Abstract A structural and electrochemical investigation of dimerization and Baker,Figgis (rotational) isomerization in the tri-ferric-substituted silicotungstates has been undertaken because these phenomena are important in a large number of polyoxometalates. A single-crystal X-ray diffraction analysis of K4Na7[(,-SiFe3W9(OH)3O34)2(OH)3] (,1) has been carried out [a = 12.9709(7) Å, b = 38.720(2) Å, c = 21.4221(12) Å, orthorhombic, Pbcm, R1 = 8.48,%, based on 13809 independent reflections]. The complex is isostructural with [(,-SiFe3W9(OH)3O34)2(OH)3]11, (,1) except that the edge-shared W3O13 caps in each [SiFe3W9(OH)3O34]4, unit are rotated by 60°. Electrochemical measurements, performed in a pH 5 acetate buffer, indicate a positive shift in the FeIII -based peak potential (and no change for the WVI -based potential) upon going from ,1 to its monomeric derivative [(,-Si(FeOH2)3W9(OH)3O34)]4, (,2) (,0.484,±,0.005 V and ,0.474,±,0.005 V, respectively). In contrast, the peak potentials of the FeIII - and WVI -based redox processes of ,1 are both found at more negative values than its rotational isomer ,1. The absolute values of the reduction peak potential differences are 0.022 V for FeIII and 0.162 V for WVI. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Structural model for an AxxxG-mediated dimer of surfactant-associated protein CFEBS JOURNAL, Issue 11 2004Visvaldas Kairys The pulmonary surfactant prevents alveolar collapse and is required for normal pulmonary function. One of the important components of the surfactant besides phospholipids is surfactant-associated protein C (SP-C). SP-C shows complex oligomerization behavior and a transition to ,-amyloid-like fibril structures, which are not yet fully understood. Besides this nonspecific oligomerization, MS and chemical cross-linking data combined with CD spectra provide evidence of a specific, mainly ,-helical, dimer at low to neutral pH. Furthermore, resistance to CNBr cleavage and dual NMR resonances of porcine and human recombinant SP-C with Met32 replaced by isoleucine point to a dimerization site located at the C-terminus of the hydrophobic ,-helix of SP-C, where a strictly conserved heptapeptide sequence is found. Computational docking of two SP-C helices, described here, reveals a dimer with a helix,helix interface that strikingly resembles that of glycophorin A and is mediated by an AxxxG motif similar to the experimentally determined GxxxG pattern of glycophorin A. It is highly likely that mature SP-C adopts such a dimeric structure in the lamellar bilayer systems found in the surfactant. Dimerization has been shown in previous studies to have a role in sorting and trafficking of SP-C and may also be important to the surfactant function of this protein. [source] Understanding the HER family in breast cancer: interaction with ligands, dimerization and treatmentsHISTOPATHOLOGY, Issue 5 2010Fabrício F T Barros Barros F F T, Powe D G, Ellis I O & Green A R (2010) Histopathology56, 560,572 Understanding the HER family in breast cancer: interaction with ligands, dimerization and treatments Breast carcinoma is the most frequent type of cancer affecting women. Among the recently described molecular and phenotypic classes of breast cancer, human epidermal growth factor receptor 2 (HER2)-positive tumours are associated with a poor prognosis. HER2 plays an important role in cancer progression being targeted to provide predictive and prognostic information. Moreover, HER2 is related to cancer resistance against a variety of therapies; however, trastuzumab (herceptin) has proved successful in treatment of this subgroup. Nevertheless, resistance to this drug may be acquired by patients after a period of treatment, which indicates that other molecular mechanisms might influence success of this therapy. Dimerization between members of the HER family may contribute to resistance against treatments due to different combinations that trigger different downstream pathways. This is promoted by ligands, which are expressed as transmembrane precursor protein molecules and have a conserved epidermal growth factor-like domain. Through resistance to trastuzumab, other drugs are being developed to interact in different domains of HER2 protein. It might be a good strategy to apply new drugs simultaneously to trastuzumab due to act in different domains of HER2. The study of interaction between receptors/ligands will characterize specifically their signalling pathway and understand which strategy to acquire. [source] Simple Preparation of Dimeric Cinchona Alkaloid Derivatives on Polystyrene Supports and a Highly Enantioselective Catalytic Heterogeneous Dimerization of KetenesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Ravindra Abstract A convenient route for the covalent immobilization of quinidine and hydroquinidine pyridazine ethers on insoluble polystyrene supports is described, which avoids the need of chromatographic purifications at any stage. The use of the heterogeneized alkaloid derivatives in the asymmetric organocatalytic dimerization of ketenes afforded high enantioselectivity values (90,97% ee) in the course of 20 reaction cycles. [source] Corrigendum: Asymmetric Dimerization of Disubstituted Ketenes Catalyzed by N-Heterocyclic CarbenesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010Hui Lv No abstract is available for this article. [source] Synthesis of Trisubstituted Pyrroles from Rhodium-Catalyzed Alkyne Head-to-Tail Dimerization and Subsequent Gold- Catalyzed CyclizationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Hong Mei Peng Abstract Dimerization of N -protected propargylic amines in a rather rare head-to-tail mode has been achieved under mild conditions with high selectivity using rhodium catalysts. The N -protecting group could be a sulfonyl, carbamate, or carbonyl functionality and (cyclooctadiene)rhodium chloride dimer/1,1,-bis(diphenylphosphino)ferrocene {[Rh(COD)Cl]2/dppf} as well as tris(triphenylphosphine)rhodium chloride [Rh(PPh3)3Cl] proved to be active catalysts. In addition, these functionalized gem -enynes subsequently undergo selective gold(III)-catalyzed intramolecular hydroamination to give trisubstituted pyrroles under mild conditions. [source] Dimerization of ionized 4-(methyl mercapto)-phenol during ESI, APCI and APPI mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2009Lianming Wu Abstract A novel ion/molecule reaction was observed to occur under electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo ionization (APPI) conditions, leading to dimerization of ionized 4-(methyl mercapto)-phenol followed by fast H· loss. The reaction is particularly favored during ESI, which suggests that this ion/molecule reaction can occur both in the solution inside the ESI-charged droplets and in the gas-phase environment of most other atmospheric pressure ionization techniques. The dimerization reaction is inherent to the electrolytic process during ESI, whereas it is more by ion/molecule chemistry in nature during APCI and APPI. From the tandem mass spectrometry (MS/MS) data, accurate mass measurements, hydrogen/deuterium (H/D) exchange experiments and density functional theory (DFT) calculations, two methyl sulfonium ions appear to be the most likely products of this electrophilic aromatic substitution reaction. The possible occurrence of this unexpected reaction complicates mass spectral data interpretation and can be misleading in terms of structural assignment as reported herein for 4-(methyl mercapto)-phenol. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dimerization or oligomerization of the actin-like FtsA protein enhances the integrity of the cytokinetic Z ringMOLECULAR MICROBIOLOGY, Issue 6 2007Daisuke Shiomi Summary In bacteria, the actin-like FtsA protein interacts with the tubulin-like FtsZ protein, helping to assemble the cytokinetic Z ring, anchor it to the cytoplasmic membrane and recruit other essential divisome proteins. FtsA also interacts with itself, but it is not clear whether this self-interaction is required for its full functionality. Here we describe new dominant negative missense mutations in Escherichia coli ftsA that specifically inhibit FtsA homodimerization and simultaneously cause disruption of Z rings. The negative effects of one mutation, M71A, were suppressed by altering levels of certain division proteins or by additional mutations in ftsA that promote increased integrity of the Z ring. Remarkably, when FtsA, FtsA-M71A, and other mutants of FtsA that compromise self-interaction were connected in a tandem repeat, they were at least partially functional and suppressed defects of an ftsZ84(ts) mutation. This gain of function by FtsA tandems further suggested that FtsA monomers cause deleterious interactions with FtsZ and that increased dimerization or oligomerization of FtsA enhances its ability to promote Z-ring integrity. Therefore, we propose that FtsZ assembly is regulated by the extent of FtsA oligomerization. [source] The strong dimerization of the transmembrane domain of the fibroblast growth factor receptor (FGFR) is modulated by C-terminal juxtamembrane residuesPROTEIN SCIENCE, Issue 2 2009Weng Chuan Peng Abstract The fibroblast growth factor receptor 3 (FGFR3) is a member of the FGFR subfamily of the receptor tyrosine kinases (RTKs) involved in signaling across the plasma membrane. Generally, ligand binding leads to receptor dimerization and activation. Dimerization involves the transmembrane (TM) domain, where mutations can lead to constitutive activation in certain cancer types and also in skeletal malformations. Thus, it has been postulated that FGFR homodimerization must be inherently weak to allow regulation, a feature reminiscent of , and , integrin TM interactions. However, we show herein that in FGFR3-TM, four C-terminal residues, CRLR, have a profound destabilizing effect in an otherwise strongly dimerizing TM peptide. In the absence of these four residues, the dimerizing propensity of FGFR3-TM is comparable to glycophorin, as shown using various detergents. In addition, the expected enhanced dimerization induced by the mutation associated to the Crouzon syndrome A391E, was observed only when these four C-terminal residues were present. In the absence of these four residues, A391E was dimer-destabilizing. Finally, using site specific infrared dichroism and convergence with evolutionary conservation data, we have determined the backbone model of the FGFR3-TM homodimer in model lipid bilayers. This model is consistent with, and correlates with the effects of, most known pathological mutations found in FGFR-TM. [source] Protein Dimerization Induced by Supramolecular Interactions with Cucurbit[8]uril,ANGEWANDTE CHEMIE, Issue 5 2010Hoang Ein Plätzchen zum Kuppeln: Proteine wie das gelb fluoreszierende Protein (YFP), die ein N-terminales FGG-Motiv tragen, dimerisieren unter Mitwirkung von supramolekularen Wechselwirkungen innerhalb des Cucurbit[8]uril-Rings (siehe Schema). Die durch FRET und Größenausschlusschromatographie beobachtbare Dimerisierung lässt sich durch Zugabe von Methylviologen umkehren, das als bioorthogonaler Ligand die FGG-Motive aus dem Cucurbit[8]uril-Wirt verdrängt. [source] Etching and Dimerization: A Simple and Versatile Route to Dimers of Silver Nanospheres with a Range of Sizes,ANGEWANDTE CHEMIE, Issue 1 2010Weiyang Li Paarbildung: Dimere von Ag-Nanokugeln unterschiedlicher Größe entstehen durch das Ätzen von Ag-Nanowürfeln mit Eisen(III)-nitrat in Ethanol in Gegenwart von Poly(vinylpyrrolidon) (PVP). Diese wohldefinierten Dimere (siehe TEM-Aufnahme) ermöglichen das systematische Studium des Hot-Spot-Phänomens bei der oberflächenverstärkten Raman-Streuung (SERS). [source] Dehydrogenative Dimerization of Di- tert -butyltin Dihydride Photochemically and Thermally Catalyzed by Iron and Molybdenum Complexes,ANGEWANDTE CHEMIE, Issue 34 2009Hemant Zinn-Zinn-Bindungen entstehen in der Titelreaktion, die in hoher Ausbeute tBu2HSnSnHtBu2 liefert , entweder photochemisch, katalysiert durch den Eisenkomplex [(,5 -C5H5)Fe(CO)2Me] oder dessen Molybdän-Analogon [(,5 -C5H5)Mo(CO)3Me], oder thermisch in Gegenwart von [(,5 -C5H5)Fe(CO)(PPh3)Me] oder [(,5 -C5H5)Mo(CO)2(PPh3)Me]. [source] Structural and functional analysis of Rv0554 from Mycobacterium tuberculosis: testing a putative role in menaquinone biosynthesisACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010Jodie M. Johnston Mycobacterium tuberculosis, the cause of tuberculosis, is a devastating human pathogen against which new drugs are urgently needed. Enzymes from the biosynthetic pathway for menaquinone are considered to be valid drug targets. The protein encoded by the open reading frame Rv0554 has been expressed, purified and subjected to structural and functional analysis to test for a putative role in menaquinone biosynthesis. The crystal structure of Rv0554 has been solved and refined in two different space groups at 2.35 and 1.9,Å resolution. The protein is dimeric, with an ,/,-hydrolase monomer fold. In each monomer, a large cavity adjacent to the catalytic triad is enclosed by a helical lid. Dimerization is mediated by the lid regions. Small-molecule additives used in crystallization bind in the active site, but no binding of ligands related to menaquinone biosynthesis could be detected and functional assays failed to support possible roles in menaquinone biosynthesis. [source] The F4 fimbrial chaperone FaeE is stable as a monomer that does not require self-capping of its pilin-interactive surfacesACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2009Inge Van Molle Many Gram-negative bacteria use the chaperone,usher pathway to express adhesive surface structures, such as fimbriae, in order to mediate attachment to host cells. Periplasmic chaperones are required to shuttle fimbrial subunits or pilins through the periplasmic space in an assembly-competent form. The chaperones cap the hydrophobic surface of the pilins through a donor-strand complementation mechanism. FaeE is the periplasmic chaperone required for the assembly of the F4 fimbriae of enterotoxigenic Escherichia coli. The FaeE crystal structure shows a dimer formed by interaction between the pilin-binding interfaces of the two monomers. Dimerization and tetramerization have been observed previously in crystal structures of fimbrial chaperones and have been suggested to serve as a self-capping mechanism that protects the pilin-interactive surfaces in solution in the absence of the pilins. However, thermodynamic and biochemical data show that FaeE occurs as a stable monomer in solution. Other lines of evidence indicate that self-capping of the pilin-interactive interfaces is not a mechanism that is conservedly applied by all periplasmic chaperones, but is rather a case-specific solution to cap aggregation-prone surfaces. [source] Chaperone-like activities of different molecular forms of ,-casein.BIOPOLYMERS, Issue 8 2009Importance of polarity of N-terminal hydrophilic domain Abstract As a member of intrinsically unstructured protein family, ,-casein (,-CN) contains relatively high amount of prolyl residues, adopts noncompact and flexible structure and exhibits chaperone-like activity in vitro. Like many chaperones, native ,-CN does not contain cysteinyl residues and exhibits strong tendencies for self-association. The chaperone-like activities of three recombinant ,-CNs wild type (WT) ,-CN, C4 ,-CN (with cysteinyl residue in position 4) and C208 ,-CN (with cysteinyl residue in position 208), expressed and purified from E. coli, which, consequently, lack the phosphorylated residues, were examined and compared with that of native ,-CN using insulin and alcohol dehydrogenase as target/substrate proteins. The dimers (,-CND) of C4-,-CN and C208 ,-CN were also studied and their chaperone-like activities were compared with those of their monomeric forms. Lacking phosphorylation, WT ,-CN, C208 ,-CN, C4 ,-CN and C4 ,-CND exhibited significantly lower chaperone-like activities than native ,-CN. Dimerization of C208 ,-CN with two distal hydrophilic domains considerably improved its chaperone-like activity in comparison with its monomeric form. The obtained results demonstrate the significant role played by the polar contributions of phosphorylated residues and N-terminal hydrophilic domain as important functional elements in enhancing the chaperone-like activity of native ,-CN. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 623,632, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Dissecting the Functions of Proteins and Pathways using Chemically Induced DimerizationCHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2006Tim Clackson No abstract is available for this article. [source] ChemInform Abstract: Nickel, Manganese, Cobalt, and Iron-Catalyzed Deprotonative Arene Dimerization.CHEMINFORM, Issue 30 2010Thanh Truong Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Gold(III) Chloride Catalyzed Intermolecular Dimerization of 2-Ethynylanilines: Synthesis of Substituted Quinolines.CHEMINFORM, Issue 10 2010C. Praveen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Palladium(II)-Catalyzed Carbonylative Dimerization of Allenyl Ketones: Efficient Synthesis of Difuranylketones.CHEMINFORM, Issue 48 2009Keisuke Kato Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Rh- and Ru-Complexes-Catalyzed Dimerization of Arylethynes in Aqueous Environment.CHEMINFORM, Issue 32 2009Petr Novak Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Selective Dimerization of 1,6-Diynes Catalyzed by Ionic Liquid-Supported Nickel Complexes in an Ionic Liquid/Toluene Biphasic System.CHEMINFORM, Issue 25 2009Avijit Goswami Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Bromine Catalyzed Dimerization of ,,,,-Dihalomonopyrrolo-TTF.CHEMINFORM, Issue 9 2008Hemant Gopee Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] An Unusual Dimerization of Primary Unsaturated Alcohols Catalyzed by RuHCl(CO)(PPh3)3.CHEMINFORM, Issue 35 2006Takashi Doi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Selective Oxidative para C,C Dimerization of 2,6-Dimethylphenol.CHEMINFORM, Issue 16 2006Christophe Boldron Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Unusual Dimerization of N-Protected Bromomethylindoles Using Phenylmagnesium Chloride.CHEMINFORM, Issue 3 2006Arasambattu K. Mohanakrishnan Abstract For Abstract see ChemInform Abstract in Full Text. [source] Rare-Earth Silylamide-Catalyzed Selective Dimerization of Terminal Alkynes and Subsequent Hydrophosphination in One Pot.CHEMINFORM, Issue 1 2006Kimihiro Komeyama Abstract For Abstract see ChemInform Abstract in Full Text. [source] Silicon-Directed Oxa-Pictet,Spengler Cyclization and an Unusual Dimerization of 2-Trimethylsilanyl Tryptophols.CHEMINFORM, Issue 39 2005Xuqing Zhang Abstract For Abstract see ChemInform Abstract in Full Text. [source] | |||||||||||||||||||||||||||||||||||||||||||