bluuebunny/crossref_metadata_2025_split huggingface dataset:
Instruction of naive CD4+ T cells by polarized CD4+ T cells within dendritic cell clusters
Authors: Creusot Rémi J. , Biswas Jason S. , Thomsen Lindy L. , Tite John P. , Mitchison N. Avrion , Chain Benjamin M. 
Published: May 2003

AbstractCooperation between CD4+ T cells can enhance the response and modulate the cytokine profile, and defining these parameters has become a major issue for multivalent‐vaccine strategies.We explored cooperation using adoptive transfer of two populations of TCR transgenic T cells of different specificity. One was transferred without prior activation, whereas the second was activatedfor five days by antigen stimulation under polarizing culture conditions. Both populations were transferred into a single adoptive host and then primed by particle‐mediated DNA delivery. Polarized Th1 cells (inducers) raised the frequency of IFN‐γ+ cells within a naive (target) population, whereas Th2 inducers raised the frequency of IL‐4+ and reduced that of IL‐2+ cells. These effects were obtained when the genes for both antigens were on the same particle, favoring presentation by the same dendritic cell, but not when on different particles delivered to different dendritic cells. Autonomy of DC clusters allows linked sets of antigens (e.g. from a single pathogen) to maintain cytokine bias, but allows other independent responses, each with their own set of autonomous clusters.
Amino acid composition of α1/α2 domains and cytoplasmic tail of MHC class I molecules determine their susceptibility to human cytomegalovirus US11‐mediated down‐regulation
Authors: Barel Martine T. , Pizzato Nathalie , van Leeuwen Daphne , Bouteiller Philippe Le , Wiertz Emmanuel J. H. J. , Lenfant Francoise 
Published: May 2003

AbstractDuring co‐evolution with its host, human cytomegalovirus has acquired multiple defense mechanisms to escape from immune recognition. In this study, we focused on US11, which binds to MHC class I heavy chains and mediates their dislocation to the cytosol and subsequent degradation by proteasomes. To examine which domains of class I heavy chains are involved in this process, we constructedchimeric HLA molecules of US11‐sensitive and ‐insensitive class I molecules (HLA‐A2 and HLA‐G, respectively). Pulse‐chase experiments were performed to evaluate protein stability and interactions between class I heavy chains and US11. Flow cytometry was employed to assess the effect of US11 on surface expression of the different chimeras. Our results indicate that the α1 and α2 domains of HLA molecules are important for the affinity of US11 association. However, the degradation efficiency seems to rely mostly on cytosolic tail residues. We found that the nonclassical HLA‐G molecule is insensitive to US11‐mediated degradation solely because it lacks essential tail residues. A deletion of the last two tail residues in full‐length MHC class I molecules already caused a severe reduction in degradation efficiency. Altogether, our data provide new insights into the mechanism by which US11 down‐regulates MHC class I molecules.
Respiratory syncytial virus‐induced CCL5/RANTES contributes to exacerbation of allergic airway inflammation
Authors: John Alison E. , Berlin Aaron A. , Lukacs Nicholas W. 
Published: May 2003

AbstractSevere respiratory syncytial virus (RSV) infection has a significant impact on airway function and may induce or exacerbate the response to a subsequent allergic challenge. In a murine model combining early RSV infection with later cockroach allergen (CRA) challenge, we examined the role of RSV‐induced CCL5/RANTES production on allergic airway responses. RSV infection increased CCL5 mRNAand protein levels, peaking at days 8 and 12, respectively. Administration of CCL5 antiserum during days 0–14 of the RSV infection did not significantly alter viral protein expression when comparedto mice treated with control serum. In mice receiving the combined RSV‐allergen challenge, lungs collected on day 22 exhibited significantly increased numbers of CD4‐ and CD8‐positive T cells. Thisincrease in T cell numbers was not observed in mice receiving α‐CCL5. On day 43, peribronchial eosinophilia and leukotriene levels were increased in RSV‐allergen mice. Pretreatment with CCL5 antiserum resulted in decreased recruitment of inflammatory cells to bronchoalveolar and peribronchial regions of the lungs and these reductions were associated with a reduction in both T cell recruitment into the bronchoalveolar space, leukotriene release and chemokine generation. Thus, CCL5 released during RSV infection has a significant effect on the inflammatory response to subsequent allergic airway challenges.
T cell receptor CDR3 loop length repertoire is determined primarily by features of the V(D)J recombination reaction
Authors: Hughes Maureen M. , Yassai Maryam , Sedy John R. , Wehrly Tara D. , Huang Ching‐Yu , Kanagawa Osami , Gorski Jack , Sleckman Barry P. 
Published: May 2003

AbstractThe third complementarity‐determining region (CDR) of the TCR α and β chains forms loops that engage amino acid residues of peptides complexed with MHC. This interaction is central to the specific discrimination of antigenic‐peptide–MHC complexes by the TCR. The TCRβ chain CDR3 loop is encoded by the Dβ gene segment and flanking portions of the Vβ and Jβ gene segments. The joining of these gene segments is imprecise, leading to significant variability in the TCRβ chain CDR3 loop length and amino acid composition. In marked contrast to other pairing antigen‐receptor chains, the TCR β and α chain CDR3 loop size distributions are relatively narrow and closely matched. Thus, pairing of TCR α and β chains with relatively similar CDR3 loop sizes may be important for generating a functional repertoire of α β TCR. Here we show that the TCRβ chain CDR3 loop size distribution is minimally impacted by TCRβ chain or α β TCR selection during thymocyte development. Rather, this distribution is determined primarily at the level of variable‐region gene assembly, and is critically dependent on unique features of the V(D)J recombination reaction that ensure Dβ gene segment utilization.
Mini‐review The role of interleukin‐12 in human infectious diseases: only a faint signature
Authors: Fieschi Claire , Casanova Jean‐Laurent 
Published: May 2003

AbstractIL‐12 is the signature IFN‐γ‐inducing cytokine and, as such, is thought to be crucial for protective immunity against intracellular microorganisms. This concept is supported by results from experimental infections of knockout mice lacking IL‐12 or the IL‐12 receptor. The description of human patients with inherited IL‐12 or IL‐12‐receptor deficiency challenges this view. Indeed, in natural conditions of infection and immunity — the hallmark of the human model — IL‐12 was found to be redundant in defense against intracellular microorganisms other than Mycobacteria and Salmonella. More surprisingly, IL‐12 was recently found to be redundant even in defense against primary intection by Mycobacteria and Salmonella in many patients, and against secondary infection by Mycobacteria but not Salmonella in most patients.
First (Peroxo)vanadium(V) Complex with Heteroligand Formed in Reaction System − Synthesis, Structure and Reactivity of K[VO(O2)(omeida)]·H2O {omeida = N‐[2‐(2‐oxomorpholine‐4‐yl)ethyl]iminodiacetato(2−)}
Authors: Sivák Michal , Mad’arová Mariana , Tatiersky Jozef , Marek Jaromír 
Published: May 2003

AbstractThe crystalline peroxo complex of vanadium(V), K[VO(O2)(omeida)]·H2O, where omeida is a δ‐lactone derivative, N‐[2‐(2‐oxomorpholine‐4‐yl)ethyl]iminodiacetate(2−), has been obtained by reaction of vanadate with H2O2 and N‐(2‐hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) in acidic aqueous solution at pH = 3 and 278 K. X‐ray analysis revealed a distorted pentagonal‐bipyramidal coordination around the vanadium atom, with a typical cis arrangement of oxo and peroxo ligands in apical and equatorial positions, respectively. Two amino nitrogen atoms of the tetradentate omeida(2−)‐N1,N2,O1,O2 ligand occupy the neighbouring equatorial positions of the pentagonal plane, and two oxygen atoms of carboxymethyl groups bound to the same N1 nitrogen atom are in equatorial and apical positions. The six‐membered lactone ring in omeida was formed in the reaction solution from carboxy and hydroxy groups not involved in coordination with the vanadium atom. The 51V NMR spectra of K[VO(O2)(omeida)]·H2O, and of peroxovanadate/HEDTA/H2O and vanadate/HEDTA/H2O solutions, as well as the 1H NMR spectrum of HEDTA, proved that lactone ring closure proceeds only in peroxovanadate but not vanadate solutions. Spectroscopic investigation of the oxygen transfer reaction from the peroxo ligand in [VO(O2)(omeida)]− to the thiolato sulfur atom in [Co(en)2{S(CH2)2NH2}]2+ or [Co(en)2(cyst)]+, and of the oxidation of N‐acetyl‐L‐cysteine by K[VO(O2)(omeida)]·H2O, revealed much more complicated reaction mechanisms than those of other (amino‐polycarboxylato)monoperoxo complexes of vanadium(V). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Extended X‐ray Absorption Fine Structure Study of Copper(I) and Copper(II) Complexes in Atom Transfer Radical Polymerization
Authors: Pintauer Tomislav , Reinöhl Ulrich , Feth Martin , Bertagnolli Helmut , Matyjaszewski Krzysztof 
Published: May 2003

AbstractExtended X‐ray Absorption Fine Structure (EXAFS) spectroscopy has been used to investigate structural features of CuIBr and CuIIBr2 complexes with dNbpy, PMDETA, Me6TREN, tNtpy, and Me4CYCLAM in various solvents {dNbpy = 4,4′‐bis(5‐nonyl)‐2,2′‐bipyridine, PMDETA = N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine, Me6TREN = tris[2‐(dimethylamino)ethyl]amine, tNtpy = 4,4′,4′′‐tris(5‐nonyl)‐2,2′:6′,2′′‐terpyridine, Me4CYCLAM = 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane}. The structures of the CuI and CuII complexes were found to depend on the solvent polarity and the number of nitrogen atoms in the ligand. Generally, in non‐polar media and with monomers typically used in ATRP, CuI complexes preferred a tetracoordinate geometry, and were either ionic as observed in [CuI(dNbpy)2]+[CuIBr2]− (CuI−NAV = 2.00 Å, CuI−BrAV = 2.25 Å) and [CuI(Me4CYCLAM)]+[CuIBr2]− (CuI−NAV = 2.06 Å, CuI−BrAV = 2.23 Å), or neutral as in [CuI(PMDETA)Br] (CuI−NAV = 2.12 Å, CuI−BrAV = 2.33 Å), and [CuI(tNtpy)Br] (CuI−NAV = 2.03 Å, CuI−BrAV = 2.29 Å). The EXAFS analysis of CuIIBr2 complexes indicated a preference for a coordination number of five, such as in [CuII(dNbpy)2Br]+[Br]− (CuII−NAV = 2.03 Å, CuII−BrAV = 2.43 Å), [CuII(PMDETA)Br2] (CuII−NAV = 2.03 Å, CuII−Br1,AV = 2.44 Å, CuII−Br2,AV = 2.64 Å) and [CuII(Me6TREN)Br]+[Br]− (CuII−NAV = 2.09 Å, CuII‐BrAV = 2.39 Å), with the exception of the neutral tetracoordinate [CuII(dNbpy)Br2] (CuII−NAV = 2.02 Å, CuII−BrAV = 2.36 Å), which has been observed in non‐polar media. Additionally, polar media were found to favor bromide dissociation in [CuII(Me6TREN)Br]+[Br]− and [CuII(PMDETA)Br2], as indicated by a decrease in the Br and Cu coordination numbers at the Cu‐ and Br‐K‐edges, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Probing the Nature of the CoIIIIon in Cobalamins − Spectroscopic and Structural Investigations of the Reactions of Aquacobalamin (Vitamin B12a) with Ambident Nucleophiles
Authors: Perry Christopher B. , Fernandes Manuel A. , Kenneth L. Brown  , Zou Xiang , Valente Edward J. , Marques Helder M. 
Published: May 2003

AbstractThe rate of substitution of the H2O β‐ligand in aquacobalamin (vitamin B12a) is surprisingly fast for CoIII. This may arise as a result of transfer of electron density to CoIIIby the corrin, conferring on the metal atom a softer and more labile character, and would require electronic communication between the equatorial ligand and the axial coordination sites of the metal atom. We have substituted H2O in B12awith the ambidentate nucleophiles SCN−, SeCN−, NO2−and S2O32−, examined the UV/Vis spectra of the resultant complexes, crystallised them, and determined their structures by X‐ray diffraction methods. The UV/Vis spectra of these complexes, as well as those of H2OCbl+, SO3Cbl−and MeCbl, were fitted by Gaussian functions. The principal bands move to lower energy in response to an increase in donation of electron density from the axial ligand, demonstrating direct electronic communication between the axial and the equatorial ligands. In the solid state, the thiocyanato ligand in SCNCbl is coordinated through N, although13C NMR spectroscopy shows that the complex exists as a mixture of two linkage isomers in solution. SeCN−, NO2−and S2O32−are coordinated through the softer available donor in each case (Se, N and S, respectively). There is a regular ground‐statetranseffect such that as the donor power of the β‐ligand increases, thetransCo−Naxbond length increases. A survey of the structures available in the CSD shows that this preference for the softer donor atom in ambidentate nucleophiles is not unusual in CoIIIcomplexes. The Co−N bond length in SCNCbl is marginally long for coordination to CoIII, but the axial bond lengths of the other complexes are as expected. Hence, whereas the corrin macrocycle clearly imparts lability on CoIII, presumably by transfer of electron density onto the metal atom, this is insufficient to have a major effect on the ground‐state structures of its complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Surface Organometallic Chemistry on Oxides: The First Well‐Defined Selenium(IV) Derivative Grafted onto Silica
Authors: Provendier Hélène , Santini Catherine C. , Basset Jean‐Marie , Carmona Laurent 
Published: May 2003

AbstractTreatment of (EtO)2SeO with Aerosil silica dehydroxylated at 500 °C results in the formation of a unique surface derivative [≡SiO−Se(O)OEt] (1), which has been fully characterized by elemental analysis, IR, labelling reaction and solid‐state NMR spectroscopy. This is the first example of a silica‐supported selenium(IV) derivative. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
New Alkali Metal Boratabenzenes: Structures of K([18]‐Crown‐6)(C5H5BMe), of the Tetrahydropyran Solvate K(3,5‐Me2C5H3B−NMe2)(THP)2, and of Two THF Solvates of K[3,5‐Me2C5H3B−N(SiMe3)2]
Authors: Zheng Xiaolai , Herberich Gerhard E. 
Published: May 2003

AbstractThe potassium salt K(C5H5BMe) (8) can be obtained from 2‐(Me3Sn)C5H5BMe (7)/KOtBu in toluene in essentially quantitative yield. Metalation of 1‐(dimethylamino)‐3‐methylene‐1,2,3,6‐tetrahydroborinine (9) with MN(SiMe3)2 (M = Na, K) in toluene afforded the unsolvated salts M(3,5‐Me2C5H3B−NMe2) (M = Na: 11; M = K: 12). Morpholino derivatives M(3,5‐Me2C5H3B−NC4H8O) (M = Li: 17; M = Na: 18) and the potassium salt K[3,5‐Me2C5H3B−N(SiMe3)2] (19) were obtained similarly. The unsolvated salts are highly air‐ and water‐sensitive, colorless powders. Crystallization with the help of auxiliary Lewis bases provided crystalline solvates K([18]‐crown‐6)(C5H5BMe) (20), K(THP)2(3,5‐Me2C5H3B−NMe2) (21), and the concomitant pseudopolymorphs K[3,5‐Me2C5H3B−N(SiMe3)2](THF)4/3 (α‐22) and K[3,5‐Me2C5H3B−N(SiMe3)2](THF)3/2 (β‐22), which were characterized structurally. The structures of α‐22 (space group C2/c) and β‐22 (space group 6122) display novel chain forms, which have no precedents in boratabenzene and cyclopentadienide chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The First Mononuclear η2‐C60 Complex of Osmium: Synthesis and X‐ray Crystal Structure of [(η2‐C60)Os(CO)(tBuNC)(PPh3)2]
Authors: Usatov Alexander V. , Martynova Ekaterina V. , Neretin Ivan S. , Slovokhotov Yuri L. , Peregudov Alexander S. , Novikov Yurii N. 
Published: May 2003

AbstractThe interaction of C60 fullerene with the cis‐dihydride osmium complex [OsH2(CO)(PPh3)3] (I) in the presence of tBuNC gives a novel metal complex [(η2‐C60)Os(CO)‐(tBuNC)(PPh3)2] (II) as the first mononuclear osmium complex with an η2‐coordinated fullerene ligand. Complex II was isolated and characterized by elemental analysis, UV, IR, 1H and 31P NMR spectroscopy. An X‐ray diffraction study of II as its dichlorobenzene solvate revealed a distorted trigonal bipyramidal coordination of the Os atom, with a 6/6 bond of C60 and two PPh3 ligands in the equatorial plane and CO and tBuNC as axial ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Assembly of Seven Nickel(II) Metals by Chiral, Salen‐Type Ligands with µ3‐OH Bridges
Authors: Xu Xuan , Gou Shaohua , Huang Wei , Ma Yonglin , Li Yizhi 
Published: May 2003

AbstractA chiral heptanuclear nickel(II) complex [NiII(NiII2L)3(μ3‐OH)2]·3H2O [H4L = (2R,3R)‐1,4‐bis(3,5‐di‐tert‐butylsalicylideneamino)‐2,3‐butanediol], containing two μ3‐OH bridges, has been prepared and structurally characterized; its thermal and magnetic properties were investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Modulation of the Prototropic Exchange Rate at the Water Molecule Coordinated to a GdIII Ion
Authors: Aime Silvio , Gianolio Eliana , Barge Alessandro , Kostakis Dimitrios , Plakatouras Ioannis C. , Hadjiliadis Nick 
Published: May 2003

AbstractThe aim of this work is to assess whether it is possible to control the rate of the prototropic exchange in a class of DTPA bis‐amide GdIII complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Tris(pyrazolyl)methanesulfonates: More Than Just Analogues of Tris(pyrazolyl)borate Ligands; N,N,N‐, N,N,O‐, and Other Coordination Modes (Eur. J. Inorg. Chem. 11/2003)
Authors: Kläui Wolfgang , Berghahn Michael , Frank Walter , Reiß Guido J. , Schönherr Thomas , Rheinwald Gerd , Lang Heinrich 
Published: May 2003

AbstractThe cover picture shows two isomers of a carbonylcopper(I) complex of the new ligand tris(pyrazolyl)methanesulfonate (Tpms). This new class of ligands contains three nitrogen donor atoms and in addition a sulfonate group which makes the ligands more hydrophilic. The sulfonate group can act as a competing donor centre. Therefore Tpms ligands are ambidentate ligands, that can adapt their coordination modes according to the electronic preferences of the metal centre. In solution, e.g., carbonylcopper(I) and zinc halide complexes show an equilibrium between the N,N,N‐ and N,N,O‐coordination mode. Synthesis, characterization and the dynamic stereochemistry of Tpms and TpmstBu complexes are presented in the article by W. Kläui et al. on p. 2059 ff. We thank B. Kugel and P. Kunz for their help with the cover picture.
UV‐Visible Spectroelectrochemical Detection of Side‐Reactions in the Hexacyanoferrate(III)/(II) Electrode Process
Authors: Heras Aránzazu , Colina Alvaro , Ruiz Virginia , López‐Palacios Jesús 
Published: May 2003

AbstractHexacyanoferrate(III)/(II) system has been studied by UV‐visible long‐pathway spectroelectrochemistry. Three different methodologies, based on potentiodynamic techniques, have been successfully used in the thermodynamic characterization of the system. Formation of soluble Prussian Blue has been detected during the electrode process. The values of the formal potential (E0′=0.200 V) and the electron stoichiometry of this side‐reaction (n=0.5) have been obtained.
Electrochemical Codeposition of Platinum and Molybdenum Oxides: Formation of Composite Films with Distinct Electrocatalytic Activity for Hydrogen Peroxide Detection
Authors: Kosminsky Luis , Matos Renato Camargo , Tabacniks Manfredo H. , Bertotti Mauro 
Published: May 2003

AbstractThe electrochemical properties of gold electrode surfaces modified by molybdenum oxide films intercalated with platinum microparticles have been described. The incorporation of Pt microparticles at the oxide film was characterized by PIXE (particle induced X‐ray emission) spectroscopy. The modified electrode showed electrochemical activity at around −0.5 V in 50 mmol L−1 Na2SO4 supporting electrolyte (pH 3), corresponding to the reduction of protons at platinum sites and further transfer of hydrogen atoms to form reduced molybdenum oxides (bronzes). At 0.1 V, the MoO3 / Pt electrode showed a better performance for hydrogen peroxide oxidation than on platinized gold electrodes. The solution pH has a marked effect on the voltammetric profile and best responses for hydrogen peroxide were obtained at the 5.0 to 6.0 pH range. The activation of the electrode by polarization at negative potentials was also studied and a mechanism by which more platinum sites are available as a consequence of this process was proposed. Calibration plots for hydrogen peroxide were highly linear (r=0.9989) in the 0.2 to 1.6 mmol L−1 concentration range, with a relative standard deviation (RSD)<1%.
Fabrication of Poly(allylamine)ferrocene Monolayer Based on Electrostatic Interaction and Its Electrocatalytic Oxidation of Ascorbic Acid
Authors: Zhang Suxia , Fu Yaqin , Sun Changqing 
Published: May 2003

AbstractA poly(allylamine)ferrocene monolayer was built on the surface of gold electrode modified with negatively charged alkanethiol based on electrostatic interaction. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry in detail. The modified electrode was shown to exhibit excellent electrocatalytic response to the oxidation of ascorbic acid. The anodic overpotential was reduced by about 170 mV compared with that obtained at a bare gold electrode. The modified electrode possesses several attractive features, such as simple preparation, fast response and good chemical and mechanical stability.
Studies on Binary Blends of Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) and Natural Polyphenol Catechin: Specific Interactions and Thermal Properties
Authors: Zhu Bo , Li Jianchun , He Yong , Inoue Yoshio 
Published: May 2003

AbstractThe existence of a specific intermolecular hydrogen‐bonding interaction between poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(3HB‐co‐3HH)] and (+)‐catechin in their blends was demonstrated by Fourier‐transform infrared spectroscopy (FT‐IR). It was found that the experimentally estimated fraction of hydrogen‐bonded carbonyl groups was much lower than the theoretically predicted maximum fraction. Only one glass transition temperature (Tg) occurred in the blends with the compositions detected by differential scanning calorimetry (DSC), being further confirmed by the results of dynamic mechanical thermal analysis (DMTA). The decrease of the melting point (Tm) and the increase of the glass transition temperature of the blends observed by the DSC measurements also suggested the existence of a strong intermolecular interaction. It was interesting to note that, as a low‐molecular‐weight compound, catechin showed a glass transition, which arises from strong self‐association. As expected, the crystalline structure of P(3HB‐co‐3HH) in the blends showed no change, but the crystallinity of the copolymer component in the blends, calculated by wide‐angle X‐ray diffraction, decreased with the increase of catechin weight content. Investigated by tensile experiments, the maximum strength and modulus decreased sharply with the increase of catechin content; on the contrary, the elongation changed slowly.The FT‐IR spectra in the wave‐number 1 680–1 780 cm−1 region for blends of P(3HB‐co‐3HH)/catechin. A: HBH; B: HBHC10; C: HBHC20; D: HBHC30; E: HBHC40; F: HBHC50; and G: catechin.magnified imageThe FT‐IR spectra in the wave‐number 1 680–1 780 cm−1 region for blends of P(3HB‐co‐3HH)/catechin. A: HBH; B: HBHC10; C: HBHC20; D: HBHC30; E: HBHC40; F: HBHC50; and G: catechin.