Activation of Ca2+ signaling in neutrophils by the mast cell-released immunophilin FKBP12.

The immunophilins of the FK506-binding protein (FKBP) family are intracellular proteins that bind the immunosuppresants FK506 and rapamycin. In this study we show that HMC-1 mast cells sensitized with IgE release FKBP12 upon stimulation with anti-IgE. The release is rapid and not affected by actinomycin D or cycloheximide, suggesting that it is due to exocytosis from a storage compartment. FKBP12 from HMC-1 mast cells exhibits biological activity. When applied extracellularly to human neutrophils, it induces transient changes in the intracellular Ca2+ concentration ([Ca2+]i) due to Ca2+ release from intracellular stores. Inhibition of [Ca2+]i changes by ruthenium red and ryanodine indicates that ryanodine receptor/Ca2+ release channels are involved in FKBP12-induced Ca2+ signaling. Neutrophil activation by mast cell-derived FKBP12 is prevented by complexing FKBP12 with FK506 or rapamycin. These results demonstrate that extracellular FKBP12 functions as a cytokine in cell-to-cell communication. They further suggest a pathophysiological role for FKBP12 as a mediator in immediate or type I hypersensitivity and may have implications for novel therapeutic strategies in the treatment of allergic disorders with FK506 and rapamycin.

Caracterização e aplicação analítica de eletrodos modificados com sistemas porfirínicos supramoleculares

Estudos com eletrodos modificados foram conduzidos utilizando dois sistemas porfirínicos supramoleculares diferentes. O primeiro foi baseado na modificação de eletrodo de carbono vítreo com uma porfirina de níquel tetrarrutenada, [NiIITPyP{RuII(bipy)2Cl}4]4+. A modificação do eletrodo foi realizada por meio de sucessivos ciclos voltamétricos em meio alcalino (pH 13), gerando um eletrodo com característica similar a eletrodos modificados com α-Ni(OH)2. A caracterização química do filme formado foi realizada através das técnicas de voltametria cíclica, ressonância paramagnética eletrônica, espectroscopia eletrônica por reflectância e espectroscopia Raman com ensaio espectro-eletroquímico. Os resultados sugerem a formação de um polímero de coordenação, [µ-O2-NiIITPyP{RuII(bipy)2Cl}4]n, composto por subunidades porfirínicas ligadas entre si por pontes µ-peroxo axialmente coordenadas aos átomos de níquel (Ni-O-O-Ni). O crescimento do filme apresentou dependência da alcalinidade do meio pela formação do precursor octaédrico [Ni(OH)2TRPyP]2+ em solução, pela coordenação de OH- nas posições axiais do átomo de níquel. O processo de eletropolimerização indicou a participação de radical hidroxil, gerado por oxidação eletrocatalítica da água nos sítios periféricos da porfirina contendo o complexo de rutênio. O mesmo eletrodo foi aplicado como sensor eletroquímico para análise amperométrica de ácido fólico em comprimidos farmacêuticos. O sensor foi associado a um sistema de Batch Injection Analysis (BIA) alcançando considerável rapidez e baixo limite de detecção. Para as análises das amostras também foi proposto um método para a remoção da lactose, que agia como interferente. O segundo estudo envolveu a modificação de eletrodos de carbono vítreo com diferentes hemoglobinas, naturais (HbA0, HbA2 e HbS) e sintéticas (Hb-PEG5K2, αα-Hb-PEG5K2 e BT-PEG5K4), para a avaliação da eficiência na redução eletrocatalítica de nitrito mediada por FeI-heme. Os filmes foram produzidos pela mistura de soluções das hemoglobinas com brometo de didodecildimetiltrimetilamônio (DDAB), aplicados nas superfícies com consecutiva evaporação, formando filmes estáveis. Os valores de potencial redox para os processos do grupo heme e a sua associação com a disponibilidade do grupo na proteína foram avaliados por voltametria cíclica. Os valores das constantes de velocidade, k, para redução de nitrito foram obtidos por cronoamperometria em -1,1 V (vs Ag/AgCl(KCl 3M)) que foram utilizados para estudo comparativo entre as espécies sintéticas para eventual aplicação clínica.

Complexos de dirutênio com os fármacos ibuprofeno, ácido acetilsalicílico, naproxeno, indometacina, e com ácido y-linolêncio: Síntese, caracterização, avaliação da ação antiproliferativa sobre células tumorais e estudo da interação da unidade dimetálica com adenina e adenosina

Este trabalho tem como principal objetivo contribuir para o desenvolvimento de novos potenciais metalofármacos de rutênio. Nele são descritas a síntese, a caracterização e a avaliação da ação antiproliferativa de alguns complexos de dirutênio (II,III) com os fármacos antiinflamatórios não-esteróides (AINEs): ibuprofeno (ibp), ácido acetilsalicílico (aas), naproxeno (npx) e indometacina (ind) e também com o ácido γ-linolênico (lin), sobre células cancerígenas. Os compostos obtidos foram caracterizados por análise elementar, espectroscopia de absorção eletrônica, medidas de susceptibilidade magnética, espectroscopia vibracional FTIR e Raman, difratometria de raios X de pó, medidas de condutividade molar e análise térmica (TG, OTAe OSC). Todos os complexos sintetizados apresentam estrutura em gaiola, com os carboxilatos derivados dos fármacos AINEs coordenados à unidade dimetálica Ru2( (II,III), em ponte equatorial, estabilizando assim a ligação direta rutênio-rutênio. As posições axiais são ocupadas por íons cloreto, no caso dos complexos [Ru2(O2(CR)4(Cl] (O2(CR = ibp, aas, npx ou ind), ou por moléculas de água, nas espécies do tipo [Ru2(O2(CR)4(H2O)2]PF6(O2CR =npx e ind). Ensaios biológicos demonstraram que os compostos [Ru2(ibp) 4Cl]•½H2O e [Ru2(npx)4(H2O)2]PF6 apresentam ação antiproliferativa sobre células de glioma de rato C6 in vitro, dependendo do tempo de exposição do meio celular ao complexo. O complexo [Ru2 (lin)4Cl] também apresenta efeito sobre a proliferação de células C6; entretanto, nesse caso, efeitos significativos são observaçlos já nas primeiras 24 h de exposição. Estudos mostraram que as bases adenina e adenosina reagem com o complexo [Ru2(OAc)4(H2O)2]PF6 sem que ocorra quebra da estrutura em gaiola. As bases nitrogenadas substituem axialmente as moléculas de água, formando pontes axiais entre duas unidades de dirutênio (II,III) no estado sólido.

Single-walled carbon nanotube buckypapers as electrocatalyst supports for methanol oxidation

This work studies the use of various single-walled carbon nanotube (SWCNT) buckypapers as catalyst supports for methanol electro-oxidation in acid media. Buckypapers were obtained by vacuum filtration from pristine and oxidized SWCNT suspensions in different liquid media. Pt–Ru catalysts supported on the buckypapers were prepared by multiple potentiostatic pulses using a diluted solution of Pt and Ru salts (2 mM H2PtCl6 + 2 mM RuCl3) in acid media. The resulting materials were characterized via SEM, TEM, EDX and ICP-OES analysis. Well dispersed rounded nanoparticles between 2 and 15 nm were successfully electrodeposited on the SWCNT buckypapers. The ruthenium content in the bimetallic deposits was between 32 and 48 at. %, while the specific surface areas of the catalysts were in the range of 72–113 m2 g−1. It was found that the solvent used to prepare the SWCNT buckypaper films has a strong influence on the catalyst dispersion, particle size and metal loading. Cyclic voltammetry and chronoamperometry experiments point out that the most active electrodes for methanol electro-oxidation were prepared with the buckypaper supports that were obtained from SWCNT dispersions in N-methyl-pyrrolidone.

Metal and precursor effect during 1-heptyne selective hydrogenation using an activated carbon as support

Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatment with H2 at 673 K. The TPR trace of the PdNRX catalyst shows that the support surface groups are greatly modified as a consequence of the use of HNO3 during the catalyst preparation. During the hydrogenation of 1-heptyne, both palladium catalysts were more active and selective than the platinum and ruthenium catalysts. The activity order of the catalysts is as follows: PdClRX > PdNRX > PtClRX ≫ RuClRX. This superior performance of PdClRX was attributed in part to the total occupancy of the d electronic levels of the Pd metal that is supposed to promote the rupture of the H2 bond during the hydrogenation reaction. The activity differences between PdClRX and PdNRX catalysts could be attributed to a better accessibility of the substrate to the active sites, as a consequence of steric and electronic effects of the superficial support groups. The order for the selectivity to 1-heptene is as follows: PdClRX = PdNRX > RuClRX > PtClRX, and it can be mainly attributed to thermodynamic effects.

Microwave-Enhanced Asymmetric Transfer Hydrogenation of N-(tert-Butylsulfinyl)imines

Microwave irradiation has considerably enhanced the efficiency of the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)imines in isopropyl alcohol catalyzed by a ruthenium complex bearing the achiral ligand 2-amino-2-methylpropan-1-ol. In addition to shortening reaction times for the transfer hydrogenation processes to only 30 min, the amounts of ruthenium catalyst and isopropyl alcohol can be considerably reduced in comparison with our previous procedure assisted by conventional heating, which diminishes the environmental impact of this new protocol. This methodology can be applied to aromatic, heteroaromatic and aliphatic N-(tert-butylsulfinyl)ketimines, leading, after desulfinylation, to the expected primary amines in excellent yields and with enantiomeric excesses of up to 96 %.

Pt- and Ru-Doped SnO2–Sb Anodes with High Stability in Alkaline Medium

Different Pt- and Ru-doped Ti/SnO2–Sb electrodes were synthesized by thermal decomposition. The effect of the gradual substitution of Sb by Ru in the nominal composition on the physicochemical and electrochemical properties were evaluated. The electrochemical stability of the electrodes was estimated from accelerated tests at 0.5 A cm–2 in 1 M NaOH. Both as-synthesized and deactivated electrodes were thoroughly characterized by scanning electron microscopy (SEM), energy-dispersive X-ray microanalysis (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction analysis (XRD). The incorporation of a small amount (about 3 at. %) of both Pt and Ru into the SnO2–Sb electrodes produced a 400-times increase in their service life in alkaline medium, with no remarkable change in the electrocatalysis of the oxygen evolution reaction (OER). It is concluded that the deactivation of the electrodes is promoted by alkaline dissolution of metal species and coating detachment at high potentials. The introduction of Pt has a coating compacting effect, and Ru(IV), at low amounts until 9.75 at. %, replaces the Sn(IV) cations in the rutile-like SnO2 structure to form a solid solution that strongly increases the stability of the electrodes. The observed Ru segregation and decreased stability for larger Ru contents (x > 9.75 at. %), together with the selective dissolution of Ru after deactivation, suggest that the formation of a homogeneous (RuδSn1−δ)O2 single-phase is crucial for the stabilization of these electrodes.

Radiochemical analysis of Bravo shot soil samples /

"January 15, 1957."

Radioactivity transport in water--environmental behavior of nitrosylruthenium : technical report 3 /

"Atomic Energy Commission Contract AT(11-1)-490."

Transition metal complexes as mediator-titrants in protein redox potentiometry

A selection of nine macrocyclic Fe-III/II and Co-III/II transition metal complexes has been chosen to serve as a universal set of mediator-titrants in redox potentiometry of protein samples. The potential range spanned by these mediators is approximately from +300 to -700 mV vs the normal hydrogen electrode, which covers the range of most protein redox potentials accessible in aqueous solution. The complexes employed exhibit stability in both their oxidized and their reduced forms as well as pH-independent redox potentials within the range 6 < pH < 9. The mediators were also chosen on the basis of their very weak visible absorption maxima in both oxidation states, which will enable (for the first time) optical redox potentiometric titrations of proteins with relatively low extinction coefficients. This has previously been impractical with organic mediators, such as indoles, viologens and quinones, whose optical spectra interfere strongly with those of the protein.

The reactions of carbon dioxide with complexes

The studies described in this thesis are concerned with the reaction of carbon dioxide and transition metal complexes of Co, Ir, Rh, Ru. Due to the important role of group VIII transition metals in homogeneous catalytic reactions, the work is mainly concerned with complexes of ruthenium.

Surface properties of enterococcus faecalis in relation to infective endocarditis

The effect of growth conditions on both the appearance and the antigenic profile of cells of Enterococcus faecalis was investigated using electron micrographs of ruthenium red stained and sectioned cells and SDS-PAGE and blotting techniques respectively. Three specific antigens of molecular weights 73, 40 and 37 kdaltons were of particular interest being expressed most strongly after growth in serum. This medium was deemed to most closely mimic jn vjvo growth conditions reflecting an environment similar to that which the microorganisms would encounter during bacteraemia, preceding the colonisation of the endocardium and the development of infective endocarditis. The 40 and 37 kdalton antigens were shown by immunoqold labelling to be exposed on the surface of the cells although they did not appear to be connected with the fimbriae shown to exist on some of the E. faecalis cells examined by negative staining. The 73, 40 and 37 kdalton antigens were crudely purified using sarkosyl and ammonium sulphate precipitation, and used as the basis of a serodiagnostic test for E. faecalis endocarditis using an ELISA system. This was tested in a blind trial and the success rates were 94% for positives, 90% for negatives with endocarditis caused by other organisms and 80% for E. faecalis infections other than endocarditis. The binding of E.faecalis cells to the serum proteins fibronectin and albumin was investigated using 125I labelled proteins, followed by Scatchard analysis. This showed that· E.faecalis cells do loosely bind large amounts of both of these proteins, thus surely affecting the way in which the host's immune system perceives the cells. The E.faecalis receptor for fibronectin was partially characterised and appeared to involve protein and/or carbohydrate containing components. but did not involve LTA or the 40 and 37 kdalton species specific antigens.

Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst:new insights into RuO2 catalytic reaction mechanisms

Five samples including a composite refuse derived fuel (RDF) and four combustible components of municipal solid wastes (MSW) have been reacted under supercritical water conditions in a batch reactor. The reactions have been carried out at 450 °C for 60 min reaction time, with or without 20 wt% RuO2/gamma-alumina catalyst. The reactivities of the samples depended on their compositions; with the plastic-rich samples, RDF and mixed waste plastics (MWP), giving similar product yields and compositions, while the biogenic samples including mixed waste wood (MWW) and textile waste (TXT) also gave similar reaction products. The use of the heterogeneous ruthenium-based catalyst gave carbon gasification efficiencies (CGE) of up to 99 wt%, which was up by at least 83% compared to the non-catalytic tests. In the presence of RuO2 catalyst, methane, hydrogen and carbon dioxide became the dominant gas products for all five samples. The higher heating values (HHV) of the gas products increased at least two-fold in the presence of the catalyst compared to non-catalytic tests. Results show that the ruthenium-based catalyst was active in feedstock steam reforming, methanation and possible direct hydrogenolysis of C-C bonds. This work provides new insights into the catalytic mechanisms of RuO2 during SCWG of carbonaceous materials, along with the possibility of producing high yields of methane from MSW fractions.

Binding of small molecules to DNA junctions

Previous results in our laboratory suggest that the (CG) 4 segments whether present in a right-handed or a left-handed conformation form distinctive junctions with adjacent random sequences. These junctions and their associated sequences have unique structural and thermodynamic properties that may be recognized by DNA-binding molecules. This study probes these sequences by using the following small ligands: actinomycin D, 1,4-bis(((di(aminoethyl)amino)ethyl)amino)anthracene-9,10-dione, ametantrone, and tris(phenanthroline)ruthenium (II). These ligands may recognize the distinctive features associated to the (CG)4 segment and its junctions and thus interact preferentially near these sequences. Restriction enzyme inhibition assays were used to determine whether or not binding interactions took place, and to approximate locations of these interactions. These binding studies are first carried out using two small synthetic oligomers BZ-III and BZ-IV. The (5meCG)4 segment present in BZ-III adopts the Z-conformation in the presence of 50 m M Co(NH3)63+. In BZ-IV, the unmethylated (CG)4 segment changes to a non-B conformation in the presence of 50 m M Co(NH3)63+. BZ-IV, containing the (CG)4 segment, was inserted into a clone plasmid then digested with the restriction enzyme Hinf I to produce a larger fragment that contains the (CG)4 segment. The results obtained on the small oligomers and on the larger fragment for restriction enzyme Mbo I indicate that 1,4-bis(((di(aminoethyl)amino)ethyl)amino)anthracene-9,10-dione binds more efficiently at or near the (CG)4 segment. Restriction enzymes EcoRV, Sac I and Not I with cleavage sites upstream and downstream of the (CG)4 insert were used to further localize binding interactions in the vicinity of the (CG)4 insert. RNA polymerase activity was studied in a plasmid which contained the (CG)4 insert downstream from the promoter sites of SP6 and T7 RNA polymerases. Activities of these two polymerases were studied in the presence of each one of the ligands used throughout the study. Only actinomycin D and spider, which bind at or near the (CG)4 segment, alter the activities of SP6 and T7 RNA polymerases. Surprisingly, enhancement of polymerase activity was observed in the presence of very low concentrations of actinomycin D. These results suggest that the conformational features of (CG) segments may serve in regulatory functions of DNA. ^