Nitrous oxide activation by picoline-derived Ni-CNP hydrides

Oxygen atom transfer (OAT) from N2O to the Ni-H bond of proton-responsive picoline-derived CNP nickel complexes has been investigated both experimentally and theoretically. These Ni-CNP complexes efficiently catalyse the reduction of N2O with pinacolborane (HBpin) under mild conditions.

Catalytic Nitrous Oxide Reduction with H2 Mediated by Pincer Ir Complexes

Reduction of nitrous oxide (N2O) with H2 to N2 and water is an attractive process for the decomposition of this greenhouse gas to environmentally benign species. Herein, a series of iridium complexes based on proton-responsive pincer ligands (1-4) are shown to catalyze the hydrogenation of N2O under mild conditions (2 bar H2/N2O (1:1), 30 °C). Among the tested catalysts, the Ir complex 4, based on a lutidine-derived CNP pincer ligand having nonequivalent phosphine and N-heterocyclic carbene (NHC) side donors, gave rise to the highest catalytic activity (turnover frequency (TOF) = 11.9 h-1 at 30 °C, and 16.4 h-1 at 55 °C). Insights into the reaction mechanism with 4 have been obtained through NMR spectroscopy. Thus, reaction of 4 with N2O in tetrahydrofuran-d8 (THF-d8) initially produces deprotonated (at the NHC arm) species 5NHC, which readily reacts with H2 to regenerate the trihydride complex 4. However, prolonged exposure of 4 to N2O for 6 h yields the dinitrogen Ir(I) complex 7P, having a deprotonated (at the P-arm) pincer ligand. Complex 7P is a poor catalytic precursor in the N2O hydrogenation, pointing out to the formation of 7P as a catalyst deactivation pathway. Moreover, when the reaction of 4 with N2O is carried out in wet THF-d8, formation of a new species, which has been assigned to the hydroxo species 8, is observed. Finally, taking into account the experimental results, density functional theory (DFT) calculations were performed to get information on the catalytic cycle steps. Calculations are in agreement with 4 as the TOF-determining intermediate (TDI) and the transfer of an apical hydrido ligand to the terminal nitrogen atom of N2O as the TOF-determining transition state (TDTS), with very similar reaction rates for the mechanisms involving either the NHC- or the P-CH2 pincer methylene linkers.

RhIII and IrIII complexes bearing NNO- heteroscorpionates and their application in catalytic transfer hydrogenation

The equimolar treatment of the bis(pyrazol-1-yl)-phenylethanol ligand with [M(Cl)3(H2O)3] precursors has been employed to obtain novel NNO-heteroscorpionate rhodiumIII (1) and iridiumIII (2) complexes. The structural fetures of 1 and 2...

Ammonia-Borane Dehydrogenation Catalyzed by Dual-Mode Proton-Responsive Ir-CNNH Complexes

Metal complexes incorporating proton-responsive ligands have been proved to be superior catalysts in reactions involving the H₂ molecule. In this contribution, a series of Ir^III complexes based on lutidine-derived CNN^H pincers containing N-heterocyclic carbene and secondary amino NHR [R = Ph (4a), tBu (4b), benzyl (4c)] donors as flanking groups have been synthesized and tested in the dehydrogenation of ammonia–borane (NH₃BH₃, AB) in the presence of substoichiometric amounts (2.5 equiv) of tBuOK. These preactivated derivatives are efficient catalysts in AB dehydrogenation in THF at room temperature, albeit significantly different reaction rates were observed. Thus, by using 0.4 mol % of 4a, 1.0 equiv of H₂ per mole of AB was released in 8.5 min (turnover frequency (TOF_50%) = 1875 h^–1), while complexes 4b and 4c (0.8 mol %) exhibited lower catalytic activities (TOF_50% = 55–60 h^–1). 4a is currently the best performing Ir^III homogeneous catalyst for AB dehydrogenation. Kinetic rate measurements show a zero-order dependence with respect to AB, and first order with the catalyst in the dehydrogenation with 4a (−d[AB]/dt = k[4a]). Conversely, the reaction with 4b is second order in AB and first order in the catalyst (−d[AB]/dt = k[4b][AB]²). Moreover, the reactions of the derivatives 4a and 4b with an excess of tBuOK (2.5 equiv) have been analyzed through NMR spectroscopy. For the former precursor, formation of the iridate 5 was observed as a result of a double deprotonation at the amine and the NHC pincer arm. In marked contrast, in the case of 4b, a monodeprotonated (at the pincer NHC-arm) species 6 is observed upon reaction with tBuOK. Complex 6 is capable of activating H₂ reversibly to yield the trihydride derivative 7. Finally, DFT calculations of the first AB dehydrogenation step catalyzed by 5 has been performed at the DFT//MN15 level of theory in order to get information on the predominant metal–ligand cooperation mode.

Iridium complexes based on CNN^H ligands containing two potential proton-responsive sites—a lutidine scaffold and a secondary amino group—have been tested in the dehydrogenation of ammonia-borane. Upon reaction with base, depending on the amino group acidity, mono- or doubly deprotonated species exhibiting significantly different catalytic activities were observed.

Hydrogenation/dehydrogenation of N-heterocycles catalyzed by ruthenium complexes based on multimodal proton-responsive CNN(H) pincer ligands

Ru complexes based on lutidine-derived pincer CNN(H) ligands having secondary amine side donors are efficient precatalysts in the hydrogenation and dehydrogenation of N-heterocycles. Reaction of a Ru-CNN(H) complex with an excess of base produces the formation of a Ru(0) derivative, which is observed under catalytic conditions.

PCBs occurrence in marine bivalves and fish from Todos os Santos Bay, Bahia, Brazil

In order to evaluate contamination by polychlorinated biphenyls (PCBs) in a tropical bay exposed to different anthropogenic pressures, samples of bivalves: mangrove oyster (Crassotrea rhizophorae), mangrove mussel (Mytella guyanensis)and clams (Anomalocardia brasiliana), were collected in different parts of Todos os Santos Bay, Bahia, Brazil. In addition, samples of bivalves and fish, purchased from a seafood market in the city of Salvador were analyzed to evaluate human exposure to PCBs through ingestion. Identification and quantification of PCBs were done by GC/MS after microwave extraction and purification with sulfuric acid. In bivalves, concentrations ranged from <0.08 to 50.1 ng g ^-1 (dry weight), with the highest values being detected in mangrove oyster, followed by clams and mangrove mussel of the Subaé estuary and Madre de Deus/Mataripe; regions known to be impacted by anthropic activities. From the total of the 12 fish species analyzed, only 5 presented levels of PCBs above the detection limit, ranging from 0.23 to 4.55 ng g ^-1 and 0.51 to 26.05 ng g ^-1 by dry weight and lipid weight, respectively. In general, concentrations of PCBs on the bay are lower than in most regions around the world, especially those located in the Northern Hemisphere. Indexes indicated that local biota and seafood from the fish market are not adversely impacted by PCBs and do not represent a risk to human health.

A functional glycoproteomics approach identifies CD13 as a novel E-selectin ligand in breast cancer

BACKGROUND

The glycan moieties sialyl-Lewis-X and/or -A (sLe^X/A) are the primary ligands for E-selectin, regulating subsequent tumor cell extravasation into distant organs. However, the nature of the glycoprotein scaffolds displaying these glycans in breast cancer remains unclear and constitutes the focus of the present investigation.

METHODS

We isolated glycoproteins that bind E-selectin from the CF1_T breast cancer cell line, derived from a patient with ductal carcinoma. Proteins were identified using bottom-up proteomics approach by nanoLC-orbitrap LTQ-MS/MS. Data were curated using bioinformatics tools to highlight clinically relevant glycoproteins, which were validated by flow cytometry, Western blot, immunohistochemistry and in-situ proximity ligation assays in clinical samples.

RESULTS

We observed that the CF1_T cell line expressed sLe^X, but not sLe^A and the E-selectin reactivity was mainly on N-glycans. MS and bioinformatics analysis of the targeted glycoproteins, when narrowed down to the most clinically relevant species in breast cancer, identified CD44 glycoprotein (HCELL) and CD13 as key E-selectin ligands. Additionally, the co-expression of sLe^X-CD44 and sLe^X-CD13 was confirmed in clinical breast cancer tissue samples.

CONCLUSIONS

Both CD44 and CD13 glycoforms display sLe^X in breast cancer and bind E-selectin, suggesting a key role in metastasis development. Such observations provide a novel molecular rationale for developing targeted therapeutics.

GENERAL SIGNIFICANCE

While HCELL expression in breast cancer has been previously reported, this is the first study indicating that CD13 functions as an E-selectin ligand in breast cancer. This observation supports previous associations of CD13 with metastasis and draws attention to this glycoprotein as an anti-cancer target.

Reaction of [TpRh(C2 H4 )2 ] with Dimethyl Acetylenedicarboxylate: Identification of Intermediates of the [2+2+2] Alkyne and Alkyne-Ethylene Cyclo(co)trimerizations

The reaction between the bis(ethylene) complex [TpRh(C2 H4 )2 ], 1, (Tp=hydrotris(pyrazolyl)borate), and dimethyl acetylenedicarboxylate (DMAD) has been studied under different experimental conditions. A mixture of products was formed, in which TpRh(I) species were prevalent, whereas the presence of trapping agents, like water or acetonitrile, allowed for the stabilization and isolation of octahedral TpRh(III) compounds. An excess of DMAD gave rise to a small amount of the [2+2+2] cyclotrimerization product hexamethyl mellitate (6). Although no catalytic application of 1 was achieved, mechanistic insights shed light on the formation of stable rhodium species representing the resting state of the catalytic cycle of rhodium-mediated [2+2+2] cyclo(co)trimerization reactions. Metallacyclopentene intermediate species, generated from the activation of one alkyne and one ethylene molecule from 1, and metallacyclopentadiene species, formed by oxidative coupling of two alkynes to the rhodium centre, are crucial steps in the pathways leading to the final organometallic and organic products.

A Novel Method for Studying the Pharmacokinetics of [(14) C]Umeclidinium After Application to the Axilla or Palm of Healthy Male Subjects

Umeclidinium (UMEC), a long-acting muscarinic antagonist approved for chronic obstructive pulmonary disease (COPD), was investigated for primary hyperhidrosis as topical therapy. This study evaluated the pharmacokinetics, safety, and tolerability of a single dose of [(14) C]UMEC applied to either unoccluded axilla (UA), occluded axilla (OA), or occluded palm (OP) of healthy males. After 8 h the formulation was removed. [(14) C]UMEC plasma concentrations (Cp) were quantified by accelerator mass spectrometry. Occlusion increased systemic exposure by 3.8-fold. Due to UMEC absorption-limited pharmacokinetics, Cp data from the OA were combined with intravenous data from a phase I study. The data were described by a two-compartment population model with sequential zero and first-order absorption and linear elimination. Simulated systemic exposure following q.d. doses to axilla was similar to the exposure from the inhaled therapy, suggesting that systemic safety following dermal administration can be bridged to the inhaled program, and offering the potential for a reduced number of studies and/or subjects.

Influence of proximity to an urban center in the pattern of contamination by marine debris

In order to test the relationship between the occurrence of marine debris and the distance from urban areas, nine beaches in the metropolitan area of Salvador, Bahia, Brazil and the adjacent northern coast were studied. Marine debris were collected, sorted in several categories and weighed. It was observed that plastics were numerically the most abundant component of the collected debris. As expected, the beaches closest to Salvador presented the largest density of debris, with the exception of the Porto da Barra beach, which has an efficient public cleaning system and does not have any vegetation, making it difficult to accumulate solid waste. Linear regression analyses showed significant relationships between the distance from the urban center (Salvador) and the number of marine debris per m(2), the total number of debris per beach (abundance), and the diversity of debris types (richness). The results showed that proximity to urban regions was a key factor in the marine debris distribution along the coast.

(Butane-1,4-di-yl)(trimethyl-phosphane-κP)[tris-(3,5-dimethyl-pyrazol-1-yl-κN (2))hydro-borato]iridium(III)

In the mononuclear title iridium(III) complex, [Ir(C₄H₈)(C₁₅H₂₂BN₆)(C₃H₉P)], which is based on the [tris­(3,5-dimethyl­pyrazol-1-yl)hydro­borato]iridium moiety, Ir[Tp^Me2], the Ir^III atom is coordinated by a chelating butane-1,4-diyl fragment and a trimethyl­phosphane ligand in a modestly distorted octa­hedral coordination environment formed by three facial N, two C and one P atom. The iridium–butane-1,4-diyl ring has an envelope conformation. This ring is disordered because alternately the second or the third C atom of the butane-1,4-diyl fragment function as an envelope flap atom (the occupancy ratio is 1:1). In the crystal, mol­ecules are organized into densely packed columns extending along [101]. Coherence between the mol­ecules is essentially based on van der Waals inter­actions.

Chlorido[1-(2-oxidophen-yl)ethyl-idene][tris-(3,5-dimethyl-pyrazol-1-yl)hydro-borato]iridium(III) chloro-form monosolvate

In the title compound, [Ir(C₁₅H₂₂BN₆)(C₈H₇O)Cl]·CHCl₃, the Ir atom is formally trivalent and is coordinated in a slightly distorted octa­hedral geometry by three facial N atoms, one C atom, one O atom and one Cl atom. The Ir=C_carbene bond is strong and short and exerts a notable effect on the trans-Ir—N bond, which is about 0.10 Å longer than the two other Ir—N bonds. The chloro­form solvent mol­ecule is anchored via a weak C—H⋯Cl hydrogen bond to the Cl atom of the Ir complex mol­ecule. In the crystal, the constituents adopt a layer-like arrangement parallel to (010) and are held together by weak inter­molecular C—H⋯Cl hydrogen bonds, as well as weak Cl⋯Cl [3.498 (2) Å] and Cl⋯π [3.360 (4) Å] inter­actions. A weak intra­molecular C—H⋯O hydrogen bond is also observed.

CD147 overexpression allows an accurate discrimination of bladder cancer patients' prognosis

BACKGROUND

Urothelial bladder carcinoma (UBC) is a chemo-sensitive tumour, but the response to treatment is heterogeneous. CD147 has been associated with chemotherapy resistance. We aimed to define tumours with an aggressive phenotype by the combined analysis of clinicopathological and biological parameters.

METHODS

77 patients with T1G3 or muscle-invasive UBC treated by radical cystectomy were studied. Immunohistochemistry was performed to detect CD147, heparanase, CD31 (blood vessels identification) and D2-40 (lymphatic vessels identification) expressions. The immunohistochemical reactions were correlated with the clinicopathological and the outcome parameters. 5-year disease-free survival (DFS) and overall survival (OS) rates were estimated using the Kaplan-Meier method. Multivariate analysis was performed by Cox proportional hazards analysis.

RESULTS

The 5-year DFS and OS rates were significantly influenced by the classical clinicopathological parameters, and by the occurrence of lymphovascular invasion. CD147 and heparanase immunoexpression did not affect patients' outcome. However, patients with pT3/pT4 tumours had a median OS time of 14.7 months (95% CI 7.1-22.3, p = 0.003), which was reduced to 9.2 months (95% CI 1.5-17.0, p = 0.008) if the tumours were CD147 positive. We developed a model of tumour aggressiveness using parameters as stage, grade, lymphovascular invasion and CD147 immunoexpression, which separated a low aggressiveness from a high aggressiveness group, remaining as an independent prognostic factor of DFS (HR 3.746; 95% CI 1.244-11.285; p = 0.019) and OS (HR 3.247; 95% CI 1.015-10.388, p = 0.047).

CONCLUSION

CD147 overexpression, included in a model of UBC aggressiveness, may help surgeons to identify patients who could benefit from a personalized therapeutic regimen. Additional validation is needed.

C-H bond activation reactions of ethers that generate iridium carbenes

Two important objectives in organometallic chemistry are to understand C-H bond activation reactions mediated by transition metal compounds and then to develop efficient ways of functionalizing the resulting products. A particularly ambitious goal is the generation of metal carbenes from simple organic molecules; the synthetic chemist can then take advantage of the almost unlimited reactivity of this metal-organic functionality. This goal remains very difficult indeed with saturated hydrocarbons, but it is considerably more facile for molecules that possess a heteroatom (such as ethers), because coordination of the heteroatom to the metal renders the ensuing C-H activation an intramolecular reaction. In this Account, we focus on the activation reaction of different types of unstrained ethers, both aliphatic and hemiaromatic, by (mostly) iridium compounds. We emphasize our recent results with the Tp(Me2)Ir(C(6)H(5))(2)(N(2)) (1.N(2)) complex (where Tp(Me2) denotes hydrotris(3,5-dimethylpyrazolyl)borate). Most of the reactivity observed with this system, and with related electronically unsaturated iridium species, starts with a C-H activation reaction, which is then followed by reversible alpha-hydrogen elimination. An alpha-C-H bond is, in every instance, broken first; when there is a choice, cleavage of the stronger terminal C(sp(3))-H bonds is always preferred over the weaker internal C(sp(3))-H (methylene) bonds of the ether. Nevertheless, competitive reactions of the unsaturated [Tp(Me2)Ir(C(6)H(5))(2)] iridium intermediate with ethers that contain C(sp(3))-H and C(sp(2))-H bonds are also discussed. We present theoretical evidence for a sigma-complex-assisted metathesis mechanism (sigma-CAM), although for other systems oxidative addition and reductive elimination events can be effective reaction pathways. We also show that additional unusual chemical transformations may occur, depending on the nature of the ether, and can result in C-O and C-C bond-breaking and bond-forming reactions, leading to the formation of more elaborate molecules. Although the possibility of extending these results to saturated hydrocarbons appears to be limited for this iridium system, the findings described in this Account are of fundamental importance for various facets of C-H bond activation chemistry, and with suitable modifications of the ancillary ligands, they could be even broader in scope. We further discuss experimental and theoretical studies on unusual alkene-to-alkylidene equilibria for some of the products obtained in the reactions of iridium complex 1.N(2) with alkyl aryl ethers. The rearrangement involves reversible alpha- and beta-hydrogen eliminations, with a rate-determining metal inversion step (supported by theoretical calculations); the alkylidene is always favored thermodynamically over the alkene. This startling result contrasts with the energetically unfavorable isomerization of free ethene to ethylidene (by about 80 kcal mol(-1)), showing that the tautomerism equilibrium can be directed toward one product or the other by a judicious choice of the transition metal complex.

Experimental and computational studies on the iridium activation of aliphatic and aromatic C-H bonds of alkyl aryl ethers and related molecules

Reaction of the Ir(III) complex [(Tp(Me2))Ir(C(6)H(5))(2)(N(2))] (1N(2)) with ortho-cresol (2-methylphenol) occurs with cleavage of the O-H and two C(sp(3))-H bonds of the phenol and formation of the electrophilic hydride alkylidene derivative [(Tp(Me2))Ir(H){=C(H)C(6)H(4)-o-O}] (2). The analogous reaction of 2-ethylphenol gives a related product 3. Both 2 and 3 have been shown to be identical to the minor, unidentified products of the already reported reactions of 1 with anisole and phenetole, respectively. Thus, in addition to the route that leads to the known heteroatom-stabilized hydride carbene [(Tp(Me2))Ir(H){=C(H)OC(6)H(4)-o-}] (B), anisole can react with 1 with cleavage of the O-CH(3) bond and formation of a new carbon-carbon bond. In contrast, only C-H bond-activation products with structures akin to B result from 1N(2) and 3,5-dimethylanisole (complex 8) or 4-fluoroanisole (9). Using anisole as a model, a computational study of the triple C-H bond activation (two aliphatic C-H bonds plus an ortho-metalation reaction) that is responsible for the formation of these heteroatom-stabilized hydride carbenes has been undertaken.

Multisite solid catalyst for cascade reactions: the direct synthesis of benzodiazepines from nitro compounds

Substituted 1,5-benzodiazepines are selectively synthesized in one pot from substituted nitroaromatics and ketones. The reaction is performed in the presence of hydrogen and in the absence of solvent by using a bifunctional solid catalyst with a chemoselective hydrogenation functional group capable of reducing the nitro group to a diamino group and an acid functional group, which catalyzes the cyclocondensation of the amino group with the ketone.

Chemoselective synthesis of substituted imines, secondary amines, and beta-amino carbonyl compounds from nitroaromatics through cascade reactions on gold catalysts

Substituted imines, alpha,beta-unsaturated imines, substituted secondary amines, and beta-amino carbonyl compounds have been synthesized by means of new cascade reactions with mono- or bifunctional gold-based solid catalysts under mild reaction conditions. The related synthetic route involves the hydrogenation of a nitroaromatic compound in the presence of a second reactant such as an aldehyde, alpha,beta-unsaturated carbonyl compound, or alkyne, which circumvents an ex situ reduction process for producing the aromatic amine. The process is shown to be highly selective towards other competing groups, such as double bonds, carbonyls, halogens, nitriles, or cinnamates, and thereby allows the synthesis of different substituted nitrogenated compounds. For the preparation of imines, substituted anilines are formed and condensed in situ with aldehydes to provide the final product through two tandem reactions. High chemoselectivity is observed, for instance, when double bonds or halides are present within the reactants. In addition, we show that the Au/TiO2 system is also able to catalyze the chemoselective hydrogenation of imines, so that secondary amines can be prepared directly through a three-step cascade reaction by starting from nitroaromatic compounds and aldehydes. On the other hand, Au/TiO2 can also be used as a bifunctional catalyst to obtain substituted beta-amino carbonyl compounds from nitroaromatics and alpha,beta-unsaturated carbonyl compounds. Whereas gold sites promote the in situ formation of anilines, the intrinsic acidity of Ti species on the support surface accelerates the subsequent Michael addition. Finally, two gold-catalyzed reactions, that is, the hydrogenation of nitro groups and a hydroamination, have been coupled to synthesize additional substituted imines from nitroaromatic compounds and alkynes.

PKU in Minas Gerais State, Brazil: mutation analysis

This work was undertaken in order to ascertain the PKU mutational spectrum in Minas Gerais, Brazil, the relative frequency of the mutations in the State and the origin of these mutations by haplotype determination. Minas Gerais is a trihybrid population formed by miscegenation from Europeans, Africans and Amerindians. All 13 exons of the PAH gene from 78 PKU patients were analyzed, including splicing sites and the promoter region. We identified 30 different mutations and 98% of the PAH alleles were established. A new mutation (Q267X) was identified as well. The most common mutations found were V388M (21.2), R261Q (16.0%), IVS10-11G>A (15.3%), I65T (5.8%), IVS2+5G>C (5.8%), R252W (5.1%), IVS2+5G>A (4.5%), P281L (3.8%) and L348V (3.2%). These nine mutations correspond to 80% of the PKU alleles in the state. Haplotypes were determined to characterize the origin of the PAH alleles. The majority of the mutations found, with respective haplotypes, are frequent in the Iberian Peninsula. However, there were some mutations that are rare in Europe and four previously unreported mutation-haplotype associations. I65T and Q267X were found in association with haplotype 38 and may be African in origin or the result of miscegenation in the Brazilian population.

Reduced arthritis in MIF deficient mice is associated with reduced T cell activation: down-regulation of ERK MAP kinase phosphorylation

Macrophage migration inhibitory factor (MIF) is a pleiotropic pro-inflammatory cytokine with many cellular targets in rheumatoid arthritis (RA). MIF has been reported to activate cells via mitogen-activated protein kinase and serine/threonine kinase (AKT or protein kinase B)-dependent signal transduction pathways. Its contribution to T cell activation and signalling in RA is not known. Using MIF -/- mice and a T cell-mediated model of RA, antigen-induced arthritis, we investigated the role of MIF in T cell activation and signalling. Arthritis severity was significantly reduced in MIF -/- mice compared with wildtype mice. This reduction was associated with decreased T cell activation parameters including footpad delayed type hypersensitivity, antigen-induced splenocyte proliferation and cytokine production. Splenocyte proliferation required extracellular signal-regulated kinase (ERK)1/2 phosphorylation, and decreased T cell activation in MIF -/- mice was associated with decreased phosphorylation of ERK1/2 but not AKT. Collectively, these data suggest that MIF promotes antigen-specific immune responses via regulation of ERK phosphorylation in T cells.

Extravasation mucocele involving the ventral surface of the tongue (glands of Blandin-Nuhn)

BACKGROUND

Mucocele is a lesion that involves the salivary glands and respective current ducts caused mainly by traumas in the affected area. Two different histological forms can be found: extravasation phenomenon and mucus-retention cyst where the former is the most frequently observed involving minor salivary glands such as the glands present in the anterior portion of the ventral surface of the tongue (glands of Blandin-Nuhn).

CASE REPORT

This report describes a large lesion involving the ventral surface of the tongue that was definitively diagnosed by histological examination as extravasation mucocele.

CONCLUSION

Important concepts are reviewed to help clinicians correctly diagnose and treat this pathology.

Formation and Cleavage of C−H, C−C, and C−O Bonds of ortho-Methyl-Substituted Anisoles by Late Transition Metals

2,6-Dimethyl-substituted anisoles can be converted into the corresponding 2-ethyl-6-methylphenols in a several-step reaction mediated by a TpMe2Ir(III) complex; use of the 13C-enriched anisoles, ArO13CH3, shows that the 13C label distributes across the two ethyl sites with a preference for the terminal position.

Iridium solutes effect C–H bond activation and C–C bond forming reactions of C6H6–MeOCH2CH2OMe solvent mixtures

The in situ generated [Tp(Me2)Ir(C(6)H(5))(2)] fragment induces both aromatic and aliphatic C-H bond activation reactions, along with C-C bond formation, when heated with benzene and 1,2-dimethoxyethane.

Coupling of internal alkynes in tp(me2)ir derivatives: selective oxidation of a noncoordinated double bond of the resulting iridacycloheptatrienes

The reaction of different Tp(Me2)Ir derivatives and dimethylacetylene dicarboxylate (DMAD) allows the preparation of three different metallacycloheptatriene complexes and an unusual allyl-terminated metallacycle. The C atoms of distant C=C bonds in the metallacycles, including aromatic ones, can be converted selectively to the corresponding keto functionality under mild conditions.

Expression of cell-cycle regulatory proteins and their prognostic value in superficial low-grade urothelial cell carcinoma of the bladder

AIMS

Cell-cycle regulatory proteins are important indicators in determining progression trough the cell-cycle and progression to invasive cancer in patients presenting with superficial bladder cancer. We performed an immunohistochemical study in order to evaluate the prognostic value of the expression of p16, p27, pRb, p53 and Ki-67 in superficial grade I and II papillary urothelial cell carcinoma of the bladder.

METHODS

p16, p27, p53, pRb and Ki-67 immunoexpression was studied in 14 pTa, 35 pT1a and 7 pT1b bladder tumours at presentation and at recurrence of their tumours. The recurrence-free survival and the progression-free survival were analysed according to these regulatory cell-cycle proteins expression.

RESULTS

For survival in univariate analysis a high Ki-67 labelling index was a poor prognostic factor for recurrence-free and progression-free survival (P=0.0014 and P=0.012, respectively). Ki-67 labelling index was also an independent recurrence-free survival prognostic factor (P=0.0005). The p16, p27, p53 and pRb immunoreactivity was not significantly associated with recurrence or progression rate in this group of bladder carcinomas.

CONCLUSIONS

These data suggest that the Ki-67 labelling index can be a reliable marker in predicting recurrence and/or progression in superficial low-grade bladder carcinomas and may be relevant in planning adjuvant therapy.

P-selectin requirement for neutrophil accumulation and injury in the direct passive Arthus reaction

The aim of this study was to investigate the role of P-selectin in the accumulation of neutrophils in the direct passive Arthus reaction in rat skin. Direct passive Arthus dermal reaction was induced in male Sprague-Dawley (SD) rats by a single i.v. injection of rat anti-sheep globulin (SG) 1 h before i.d. injection of SG antigen. Anti-P-selectin or irrelevant control antibody was given 1 h before rat anti-SG injection. Complement depletion was also performed in a separate group by pretreatment with cobra venom factor (CVF). In all groups dermal swelling was assessed 4 h after antigen challenge. Four hours after antigen challenge, rats treated with control antibody developed skin swelling (2.29 +/- 0.47 mm), prominent complement deposition and neutrophil accumulation. This response was associated with local up-regulation of endothelial P-selectin. Pre-treatment with anti-P-selectin antibody 1 h before passive Arthus induction prevented skin swelling (0.29 +/- 0.06 mm, P < 0.05, cf with control antibody treatment), neutrophil accumulation and up-regulation of endothelial P-selectin despite complement deposition. CVF treatment prevented complement deposition, neutrophil accumulation and skin swelling (0.13 +/- 0.07 mm, P < 0.05, cf with saline treatment). However, endothelial P-selectin expression was still present. Inhibition of skin swelling and neutrophil accumulation in direct passive Arthus by functional inhibition of P-selectin suggest a pivotal role for this adhesion molecule in this inflammatory process. These results also suggest that multiple steps are involved in the evolution of direct passive Arthus, including both P-selectin expression and complement activation. However, while complement activation is essential for neutrophil accumulation and expression of dermal injury, P-selectin up-regulation initiated by antibody/antigen deposition occurs independently of complement activation.

Glucocorticoid inhibition of adjuvant arthritis synovial macrophage nitric oxide production: role of lipocortin 1

Nitric oxide (NO) is a mediator of inflammatory injury which is inhibited by glucocorticoids and is implicated in rheumatoid (RA) and adjuvant arthritis (AA). The glucocorticoid-induced anti-inflammatory molecule lipocortin 1 is expressed in RA synovium, but the effects of lipocortin 1 on synovial inflammation have been little studied. We investigated the effects of glucocorticoids and lipocortin 1 on inducible NO synthase (iNOS) and glucocorticoids on the induction of lipocortin 1 in AA synovial macrophages. NO production was measured by Griess assay in supernatants of day 14 AA rat synovial explants and of synovial macrophages purified from enzyme-digested synovium and treated with lipopolysaccharide (LPS) 1 microg/ml, dexamethasone (DEX) 10(-7) M, and anti-lipocortin 1 MoAb. iNOS and lipocortin 1 expression were detected by flow cytometry using specific MoAb. Cell surface lipocortin was determined by Western blot. NO was produced by all AA synovial explants and NO was released by cultured synovial macrophages (14.5 +/- 2.1 micromol/24 h). iNOS was detected in synovial macrophages (ED-1+) by permeabilization flow cytometry. LPS increased synovial macrophage NO release (P < 0.0001) and iNOS expression (P = 0.04). DEX inhibited constitutive (P = 0.002) and LPS-induced (P < 0.001) NO release and iNOS expression (P = 0.03). DEX inhibition of synovial macrophage NO was associated with induction of cell surface and intracellular lipocortin 1. Anti-lipocortin 1 MoAb treatment reduced the inhibition of NO release by DEX (P = 0.002), but had no effect on iNOS expression. These findings demonstrate a role for lipocortin I in the inhibition by glucocorticoids of AA synovial macrophage iNOS activity.

Suppression of adjuvant arthritis and synovial macrophage inducible nitric oxide by N-iminoethyl-L-ornithine, a nitric oxide synthase inhibitor

Nitric oxide (NO.) is a pro-inflammatory effector molecule in certain inflammatory diseases, including arthritis. We investigated the production of NO. by adjuvant arthritis (AA) synovial macrophages, and studied the effects of a NO. synthase inhibitor. N-iminoethyl-L-ornithine (L-NIO). Compared to control rats, rats treated with L-NIO in vivo exhibited significantly lower articular index (p < 0.05), paw volume (p < 0.05), and synovial fluid cell count (p < 0.05). No effect on cutaneous delayed-type hypersensitivity to the disease-initiating antigen was observed. Inducible NO. synthase (iNOS) was detected in AA synovial macrophages, and cultured AA synovial macrophage iNOS levels were increased by a factor of 138 +/- 17% (p < 0.01) by 1 microgram/ml LPS in vitro. Constitutive NO. production by AA synovial macrophages (43 +/- 1 nmol/10(5) cells/24 h) was significantly inhibited by 10 nM L-NIO in vitro (32 +/- 0.5, p < 0.01). NO. production induced by 1 microgram/ml LPS (48 +/- 2) was also decreased by L-NIO (39 +/- 2, p < 0.05). In vivo L-NIO treatment also inhibited alveolar macrophage NO. production (p < 0.05). The ability of L-NIO to decrease iNOS-mediated synovial macrophage NO. production and inhibit the clinical parameters of AA implicate macrophage-derived NO. in the pathogenesis of this disease.

Anti-neutrophil monoclonal antibody therapy inhibits the development of adjuvant arthritis

The aim of this study was to determine the contribution of neutrophils to adjuvant arthritis (AA) by in vivo depletion of peripheral blood neutrophils. Specific anti-neutrophil MoAb, RP3 (10 mg), or a control antibody was given twice daily on days 8-11 after injection of Mycobacterium tuberculosis in inbred male Sprague-Dawley rats. RP3 treatment inhibited the neutrophil leukocytosis associated with AA (3.3 +/- 0.6 x 10(3)/mm3 versus 21.2 +/- 6.9 x 10(3)/mm3; P<0.001). On day 12, control animals exhibited severe arthritis as assessed by articular index (AI) (9.2 +/- 1.3), increase in paw volume (149.3 +/- 10.6%), and synovial fluid (SF) cell count (5.3 +/- 0.5 x 10(5)). RP3 treatment significantly reduced AI (1 +/- 0.1; P<0.001), paw volume (103.6 +/- 5.8%; P<0.001) and SF cells (0.6 +/- 0.1 x 10(5); P<0.001) without affecting cutaneous DTH (treated 0.6 +/- 0.1 mm change in thickness, control 0.8 +/- 0.2 mm; NS). Additional experiments demonstrated that CD4+ cell depletion but not decomplementation inhibited AA development and synovial neutrophil accumulation. Depletion of circulating neutrophils prevented joint inflammation and synovial leucocyte influx in AA, suggesting a pivotal role for neutrophils in the effector phase of AA. Inhibition of neutrophil accumulation by CD4+ cell depletion and not by decomplementation suggests that neutrophil accumulation in AA is T cell-dependent.