CD207+ CD103+ dermal dendritic cells cross-present keratinocyte-derived antigens irrespective of the presence of Langerhans cells.

Recent studies have challenged the view that Langerhans cells (LCs) constitute the exclusive antigen-presenting cells of the skin and suggest that the dermal dendritic cell (DDC) network is exceedingly complex. Using knockin mice to track and ablate DCs expressing langerin (CD207), we discovered that the dermis contains five distinct DC subsets and identified their migratory counterparts in draining lymph nodes. Based on this refined classification, we demonstrated that the quantitatively minor CD207+ CD103+ DDC subset is endowed with the unique capability of cross-presenting antigens expressed by keratinocytes irrespective of the presence of LCs. We further showed that Y-Ae, an antibody that is widely used to monitor the formation of complexes involving I-Ab molecules and a peptide derived from the I-E alpha chain, recognizes mature skin DCs that express I-Ab molecules in the absence of I-E alpha. Knowledge of this extra reactivity is important because it could be, and already has been, mistakenly interpreted to support the view that antigen transfer can occur between LCs and DDCs. Collectively, these data revisit the transfer of antigen that occurs between keratinocytes and the five distinguishable skin DC subsets and stress the high degree of functional specialization that exists among them.

Structure of Adenine on Metal Nanoparticles: pH Equilibria and Formation of Ag+ Complexes Detected by Surface-Enhanced Raman Spectroscopy

The SERS spectra of adenine recorded under a broad range of pH values and concentrations using both silver and gold colloids provided evidence for the existence of several distinct species. At high concentration (0.5-10 ppm), the spectra recorded between pH 1 and 11 showed only two distinct spectra, rather than the three forms that would be expected for a compound with two pK(a) values of 4.2 and 9.8. The spectra at neutral and alkaline pH were identical and assigned to the deprotonated form of adenine on the basis of DFT calculations, isotope shifts, and comparison with the normal Raman spectra of neutral and deprotonated adenine. The spectra at acidic pH were different, consistent with adenine protonation. Neutral adenine was not detected at any pH studied. At low adenine concentration (

Sequential C-H and C-Ru bond formation and cleavage during the thermally induced rearrangement of aryl ruthenium(II) complexes with [C6H3(CH2NMe2)(2)-2,6](-) as a bidentate eta(2)-C,N coordinated ligand. The crystal structures of the isomeric pairs [RuCl{eta(6)-C10H14}{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,n}] (n = 4 or 6) and [Ru(eta(5)-C5H5){(eta(2)-C,N-C6H3(CH2NMe2)(2)-2,n} (PPH3)] (n = 4 or 6)

New air-stable ruthenium(II) complexes that contain the aryldiamine ligand [C6H3(CH2-NMe2)(2)-2,6](-) (NCN) are described. These complexes are [RuCl{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,6}(eta(6)-C10H14)] (2; C10H14 = p-cymene = C6H4Me-Pr-i-4), [Ru{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,6}(eta(5)-C5H5)(PPh3)] (5), and their isomeric forms [RuCl{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,4}(eta(6)-C10H14)] (3) and [Ru{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,4}(eta(5)-C5H5)(PPh3)] (6), respectively. Complex 2 has been prepared from the reaction of [Li(NCN)](2) with [RuCl2(eta(6)-C10H14)](2), whereas complex 5 has been prepared by the treatment of [RuCl{eta(3)-N,C,N-C6H3(CH2NMe2)(2)-2,6}(PPh3)] (4) with [Na(C5H5)](n). Both 2 and 5 are formally 18-electron ruthenium(II) complexes in which the monoanionic potentially tridentate coordinating ligand NCN is eta(2)-C,N-bonded, In solution (halocarbon solvent at room temperature or in aromatic solvents at elevated temperature), the intramolecular rearrangements of 2 and 5 afford complexes 3 and 6, respectively. This is a result of a shift of the metal-C-aryl bond from position-1 to position-3 on the aromatic ring of the NCN ligand. The mechanism of the isomerization is proposed to involve a sequence of intramolecular oxidative addition and reductive elimination reactions of both aromatic and aliphatic C-H bonds. This is based on results from deuterium labeling, spectroscopic studies, and some kinetic experiments. The mechanism is proposed to contain fully reversible steps in the case of 5, but a nonreversible step involving oxidative addition of a methyl NCH2-H bond in the case of 2. The solid-state structures of complexes 2, 3, 5, and 6 have been determined by single-crystal X-ray diffraction. A new dinuclear 1,4-phenylene-bridged bisruthenium(II) complex, [1,4-{RuCl(eta(6)-C10H14)}(2){C-6(CH2NMe2)(4)-2,3,5,6-C,N,C',N'}] (9) has also been prepared from the dianionic ligand [C-6(CH2NMe2)(4)-2,3,5,6](2-) (C2N4). The C2N4 ligand is in an eta(2)-C,N-eta(2)-C',N'-bis(bidentate) bonding mode. Compound 9 does not isomerize in solution (halocarbon solvent), presumably because of the absence of an accessible C-aryl-H bond. Complex 9 could not be isolated in an analytically pure form, probably because of its high sensitivity to air and very low solubility, which precludes recrystallization.

Uptake, translocation and transformation of arsenate and arsenite in sunflower (Helianthus annuus):formation of arsenic-phytochelatin complexes during exposure to high arsenic concentrations

The aim of the study was to determine the time-dependent formation of arsenic-phytochelatin (As-PC) complexes in the roots, stems and leaves of an arsenic-nontolerant plant (Helianthus annuus) during exposure to 66 mol l(-1) arsenite (As(III)) or arsenate (As(V)). We used our previously developed method of simultaneous element-specific (inductively coupled plasma mass spectrometry, ICP-MS) and molecular-specific (electrospray-ionization mass spectrometry, ES-MS) detection systems interfaced with a suitable chromatographic column and eluent conditions, which enabled us to identify and quantify As-PC complexes directly. Roots of As-exposed H. annuus contained up to 14 different arsenic species, including the complex of arsenite with two (gamma-Glu-Cys)(2)-Gly molecules [As((III))-(PC(2))(2)], the newly identified monomethylarsonic phytochelatin-2 or (gamma-Glu-Cys)(2)-Gly CH(3)As (MA((III))-PC(2)) and at least eight not yet identified species. The complex of arsenite with (gamma-Glu-Cys)(3)-Gly (As((III))-PC(3)) and the complex of arsenite with glutathione (GSH) and (gamma-Glu-Cys)(2)-Gly (GS-As((III))-PC(2)) were present in all samples (roots, stems and leaves) taken from plants exposed to As. The GS-As((III))-PC(2) complex was the dominant complex after 1 h of exposure. As((III))-PC(3) became the predominant As-PC complex after 3 h, binding up to 40% of the As present in the exposed plants. No As-PC complexes were found in sap (mainly xylem sap from the root system), in contrast to roots, stems and leaves, which is unequivocal evidence that As-PC complexes are not involved in the translocation of As from root to leaves of H. annuus.

Efficient heterogeneous asymmetric catalysis of the Mukaiyama aldol reaction by silica- and ionic liquid-supported Lewis acid copper(II) complexes of bis(oxazolines)

Lewis acid complexes based on copper(II) and an imidazolium-tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1-methoxy-1-tri-methylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ees obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2 min compared with only 55% conversion after 60 min in dichloromethane. However, this rate enhancement was offset by lower chemoselectivity in ionic liquids due to the formation of 3-hydroxy-1,3-diphenylbutan-1-one as a by-product. Supporting the catalyst on silica or an imidazolium-modified silica using the ionic liquid or in an ionic liquid-diethyl ether system completely suppressed the formation of this by-product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee.

Polynuclear metal complexes obtained from the task-specific ionic liquid betainium bistriflimide

The task-specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used to dissolve metal oxides and hydroxides. The crystal structures of the resulting metal betaine bistriflimide complexes exhibit a rich structural variety. A trimeric structure was found for the cobalt(II) compound, [Co-3(bet)(8)(Hbet)(2)(H2O)(2)][Tf2N](9)[Hbet], a tetrameric structure for the manganese(II) and zinc(II) compound, [Mn-4(bet)(10)(H2O)(4)][Tf2N](8) and [Zn-4(bet)(10)(H2O)(2)][Tf2N](8), respectively, a pentameric structure for the nickel(II) compound, [Ni-5(bet)(12)(H2O)(6)][Tf2N](10), an oxo-hydroxo-cluster formation for the lead(II) compound, [(Pb4O)Pb(OH)(bet)(8)(Tf2N)3] [Tf2N](4)center dot MeOH, and a polymeric structure for the silver(I) compound, [Ag-2(bet)(2)(Tf2N)Ag-2(bet)(2)][Tf2N](3). The zwitterionic nature of the betaine ligand and the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide [Tf2N]- anion facilitates the incorporation of metal ions into oligonuclear and polynuclear metal complexes.

Species distribution and coordination of uranyl chloro complexes in acetonitrile

The complex formation of the uranyl ion, UO22+, with chloride ions in acetonitrile has been investigated by factor analysis of UV-vis absorption and U L-3 edge EXAFS (extended X-ray absorption fine structure) spectra. As a function of increasing [Cl-]/[UO22+] ratio, the five monomeric species [UO2(H2O)(5)](2+), [UO2Cl(H2O)(2)(MeCN)(2)](+), [UO2Cl2(H2O)(MeCN)(2)], [UO2Cl3(MeCN)(2)](-), and [UO2Cl4](2-) have been observed. The distances determined in the first coordination sphere are: U-O-ax = 1.77 angstrom, U-O-H2O = 2.43 angstrom, U-N-MeCN = 2.53 angstrom, and U-Cl = 2.68 angstrom. A crystalline material has been obtained from the intermediate solution with the [Cl-]/[UO22+] ratio of similar to 2, where [UO2Cl2(H2O)(MeCN)(2)] is the dominating species. The crystal structure analysis of this material revealed a tetrameric complex, [(UO2)(4)(mu(2)-Cl)(4)(mu(3)-O)(2)(H2O)(2)(CH3CN)(4)]center dot(CH3CN). The crystal data are: monoclinic, space group P2(1)/n, a 10.6388(5) angstrom, b = 14.8441(5) angstrom, c = 10.8521(5) angstrom, beta = 109.164(5)degrees, and Z = 2. The U(VI) coordination of the solution species [UO2Cl2(H2O)(MeCN)(2)] changes during the crystallization by replacing one MeCN molecule with a bridging mu(3)-O atom in the tetramer.

Proteomic analysis of circulating immune complexes in juvenile idiopathic arthritis reveals disease-associated proteins

Juvenile idiopathic arthritis reflects a group of clinically heterogeneous arthritides hallmarked by elevated concentrations of circulating immune complexes. In this study, the circulating immune complex proteome was examined to elucidate disease-associated proteins that are overexpressed in patients with an aggressive, and at times destructive, disease phenotype. To solve this proteome, circulating immune complexes were isolated from the sera of patients with chronic, erosive or early-onset, aggressive disease and from patients in medical remission or healthy controls subsequent to protein separation by 2-DE. Thirty-seven protein spots were overexpressed in the circulating immune complexes of the aggressive disease groups as compared to controls, 28 of which have been confidently identified to date. Proteolytic fragments of glyceraldehyde-3-phosphate dehydrogenase, serotransferrin, and a-1-antitrypsin have been identified among others. In total, these 28 putative disease-associated proteins most definitely contribute to immune complex formation and likely have a significant role in disease etiology and pathogenesis. Moreover, these proteins represent markers of aggressive disease, which could aid in diagnosis and management strategies, and potential therapeutic targets to prevent or control disease outcome. This is the first in-depth analysis of the circulating immune complex proteome in juvenile idiopathic arthritis.

Mandelohydroxamic acid as ligand for copper(II) 15-metallacrown-5 lanthanide(III) and copper(II) 15-metallacrown-5 uranyl complexes

The formation of pentanuclear copper(ii) complexes with the mandelohydroxamic ligand was studied in solution by electrospray ionization mass spectrometry (ESI-MS), absorption spectrophotometry, circular dichroism and H-1 NMR spectroscopy. The presence of lanthanide(iii) or uranyl ions is essential for the self-assembly of the 15-metallacrown-5 compounds. The negative mode ESI-MS spectra of solutions containing copper(II), mandelohydroxamic acid and lanthanide(iii) ions (Ln = La, Ce, Nd, Eu, Gd, Dy, Er, Tm, Lu, Y) or uranyl in the ratio 5:5:1 showed only the peaks that could be unambiguously assigned to the following intact molecular ions: {Ln(NO3)(2)[15-MCuIIN(MHA)-5](2-)}(-) and {Ln(NO3)[15-MCCuIIN(MHA)-5](3-)}(-), where MHA represents doubly deprotonated mandelohydroxamic acid. The NMR spectra of the pentanuclear species revealed only one set of peaks indicating a fivefold symmetry of the complex. The pentanuclear complexes synthesized with the enantiomerically pure R- or S-forms of mandelohydroxamic acid ligand, showed circular dichroism spectra which were mirror images of each other. The pentanuclear complex made from the racemic form of the ligand showed no signals in the CD spectrum. The UV/ Vis titration experiments revealed that the order in which the metal salts are added to the solution of the mandelohydroxamic acid ligand is crucial for the formation of metallacrown complexes. The addition of copper(ii) to the solutions containing mandelohydroxamic acid and neodymium(iii) in a 5:1 ratio lead to the formation of a pentanuclear complex in solution. In contrary, titration of lanthanide(iii) salt to the solution containing copper(ii) and mandelohydroxamic acid did not show any evidence for the formation of pentanuclear species. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

MEASUREMENT OF SUPEROXIDE FORMATION BY MITOCHONDRIAL COMPLEX I OF YARROWIA LIPOLYTICA

Complex I (NADH: ubiquinone oxidoreductase) is generally regarded as one of the major sources of mitochondrial reactive oxygen species (ROS). Mitochondrial membranes from the obligate aerobic yeast Yarrowia lipolytica, as well as the purified and reconstituted enzyme, can be used to measure complex I-dependent generation of superoxide (O-2(center dot-)). The use of isolated complex I excludes interference with other respiratory chain complexes and matrix enzymes during superoxide dismutase-sensitive reduction of acetylated cytochrome c. Alternately. hydrogen peroxide formation can be measured by the Amplex Red/horseradish peroxidase assay. Both methods allow the determination of complex I-generated ROS, depending on substrates (NADH, artificial ubiquinones), membrane potential, and active/deactive transition. ROS production by Yorrowia complex I in the

Uranyl Complexes of Carboxyl-Functionalized Ionic Liquids

Uranium(VI) oxide has been dissolved in three different ionic liquids functionalized with a carboxyl group: betainium bis[trifluoromethyl)sulfonyl]imide, 1-(carboxymethyl)-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and N-(carboxymethyl)-N-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide. The dissolution process results in the formation of uranyl complexes with zwitterionic carboxylate ligands and bis[trifluoromethyl)sulfonyl]imide (bistriflimide) counterions. An X-ray diffraction study on single crystals of the uranyl complexes revealed that the crystal structure strongly depends on the cationic core appended to the carboxylate groups. The betainium ionic liquid gives a dimeric uranyl complex, the imidazolium ionic liquid a monomeric complex, and the pyrrolidinium ionic liquid a one-dimensional polymeric uranyl complex, Extended X-ray absorption fine structure measurements have been performed on the betainium uranyl complex. The absorption and luminescence spectra of the uranyl betainium complex have been studied in the solid state and dissolved in water, in acetonitrile, and in the ionic liquid betainium bistriflimide. The carboxylate groups remain coordinated to uranyl in acetonitrile and in betainium bistriflimide but not in water.

Solid and liquid charge-transfer complex formation between 1-methylnaphthalene and 1-alkyl-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide ionic liquids

Liquid charge-transfer (CT) complexes were observed to form on contacting electron-rich aromatics with electron withdrawing group appended 1-alkyl-4-cyanopyridinium ionic liquids (ILs). Cooling below the melting point of the ionic liquid resulted in crystallisation of ionic liquid from the complex for 2-cyano and 3-cyano pyridinium isomers and in the formation of a 1 : 1 IL : aromatic crystalline CT-complex with the 4-cyanopyridinium isomer. The liquid structure of a 1 : 1 mixture of 1-methyl-4-cyanopyridinium bis{(trifluoromethyl)sulfonyl} imide with 1-methylnaphthalene has been probed by neutron diffraction experiments and molecular dynamics simulations. A high degree of correlation between the experimental data and the simulations was found with a significant displacement of the anions from around the cation by the aromatic species and the resulting structure having pi-pi stacks between the cations and the aromatic.

Surface enhanced Raman evidence for Ag+ complexes of adenine, deoxyadenosine and 5'-dAMP formed in silver colloids

We report the formation of highly scattering silver complexes of adenine, deoxyadenosine and 5'-dAMP under alkaline pH conditions in the colloidal silver solutions which are used for surface-enhanced Raman spectroscopy. These complexes, and other pH-dependent phenomena, help to explain the diversity of previously reported adenine SERS spectra. Using conditions which promote complex formation allows nucleotides to be detected at <1 ppm, even in solutions with high salt concentrations.

Corticosteroids and peritonsillar abscess formation in infectious mononucleosis

Peritonsillar abscess formation is an uncommon complication of infectious mononucleosis (IM). Early case reports implicated corticosteroids in the development of such abscesses, however, subsequent studies suggested that these drugs do not promote the formation of abscesses at several sites outside the central nervous system. It has recently been demonstrated that zwitterionic polysaccharides, in bacterial capsules, form complexes with CD4(+) T lymphocytes leading to abscess formation. A patient is presented who developed peritonsillar abscess a few days after initiation of corticosteroid therapy for IM; the medical literature was reviewed in respect of this subject. It appears that the occurrence of these abscesses in IM is not strongly linked to corticosteroid treatment. The authors, therefore, recommend that steroids should not be withheld from patients with severe IM on the basis that they may precipitate the development of peritonsillar abscess.

Can arsenic-phytochelatin complex formation be used as an indicator for toxicity in Helianthus annuus?

The formation of arsenic-phytochelatin (As-PC) complexes is thought to be part of the plant detoxification strategy for arsenic. This work examines (i) the arsenic (As) concentration-dependent formation of As-PC complex formation and (ii) redistribution and metabolism of As after arrested As uptake in Helianthus annuus. HPLC with parallel ICP-MS/ES-MS detection was used to identify and quantify the species present in plant extracts exposed to arsenate (As(V)) (between 0 and 66.7 micromol As l-1 for 24 h). At As concentrations below the EC50 value for root growth (22 micromol As l-1) As uptake is exponential, but it is reduced at concentrations above. Translocation between root and shoot seemed to be limited to the uptake phase of arsenic. No redistribution of As between root and shoot was observed after arresting As exposure. The formation of As-PC complexes was concentration-dependent. The amount and number of As-PC complexes increased exponentially with concentration up to 13.7 micromol As l-1. As(III)-PC3 and GS-As(III)-PC2 complexes were the dominant species in all samples. The ratio of PC-bound As to unbound As increased up to 1.3 micromol As l-1 and decreased at higher concentrations. Methylation of inorganic As was only a minor pathway in H. annuus with about 1% As methylated over a 32 d period. The concentration dependence of As-PC complex formation, amount of unbound reduced and oxidized PC2, and the relative uptake rate showed that As starts to influence the cellular metabolism of H. annuus negatively at As concentrations well below the EC50 value determined by more traditional means. Generally, As-PC complexes and PC-synthesis rate seem to be the more sensitive parameters to be studied when As toxicity values are to be estimated.