Quantification of β‐aminopropionitrile,an inhibitor of lysyl oxidase activity,in plasma and tumor of mice by liquid chromatography tandem mass spectrometry

Lysyl oxidase enzymes are reported to be involved in patho‐physiological process such as tumorigenesis. β‐Aminopropionitrile (BAPN) is an irreversible inhibitor of lysyl oxidase activity, suggesting a potentially useful therapeutic of interest in oncology. This paper describes the first assay concerning the quantification of BAPN by mass spectrometry. A high‐performance liquid chromatography tandem mass spectrometry (LC‐MS/MS) assay was developed for the quantification of BAPN in plasma and tumor of mice. This method combines dansyl chloride (Dns) derivatization and extraction using a solid‐phase extraction Oasis^© Max column. Deuterated BAPN was used as internal standard (IS). Separation was achieved using an C₁₈ column HypersylGold, (ThermoElectron), 3.0 µm (100 × 2.1 mm i.d.). Gradient elution with water containing 0.1% acetic acid (A) and acetonitrile containing 0.1% acetic acid (B) was applied. Detection was performed with an electrospray ionization interface operating in negative ion mode. Selected reaction monitoring was used with ion transitions m/z 302 → 249 for BAPN–Dns and m/z 306 → 250 for the IS. The method was fully validated in plasma and was linear and sensitive in the range of 10–500 ng/mL. The lower limit of quantification in plasma was 2.5 ng/mL. This validated assay was successfully applied to a kinetic study of BAPN in mouse plasma and demonstrates that BAPN reaches the tumoral tissue. Copyright © 2014 John Wiley & Sons, Ltd.     

Nickel(II) meso‐Hydroxyporphyrin Complexes Revisited: Palladium‐Catalysed Synthesis,Electronic Structures of Derived Oxy Radicals,and Oxidative Coupling to a Dioxoporphodimethene Dyad

We report the synthesis and characterisation of new examples of meso‐hydroxynickel(II) porphyrins with 5,15‐diphenyl and 10‐phenyl‐5,15‐diphenyl/diaryl substitution. The OH group was introduced by using carbonate or hydroxide as nucleophile by using palladium/phosphine catalysis. The NiPor?OHs exist in solution in equilibrium with the corresponding oxy radicals NiPor?O^.. The 15‐phenyl group stabilises the radicals, so that the ¹H NMR spectra of {NiPor?OH} are extremely broad due to chemical exchange with the paramagnetic species. The radical concentration for the diphenylporphyrin analogue is only 1 %, and its NMR line‐broadening was able to be studied by variable‐temperature NMR spectroscopy. The EPR signals of NiPor?O^. are consistent with somewhat delocalised porphyrinyloxy radicals, and the spin distributions calculated by using density functional theory match the EPR and NMR spectroscopic observations. Nickel(II) meso‐hydroxy‐10,20‐diphenylporphyrin was oxidatively coupled to a dioxo‐terminated porphodimethene dyad, the strongly red‐shifted electronic spectrum of which was successfully modelled by using time‐dependent DFT calculations.     

Direct Synthesis of Peptide-Containing Silicones: A New Way to Bioactive Materials

A simple and efficient way to synthesize peptide-containing silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si(vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active silicones.     

hcp‐Co Nanowires Grown on Metallic Foams as Catalysts for Fischer–Tropsch Synthesis

The Fischer–Tropsch synthesis (FTS) is a structure‐sensitive exothermic reaction that enables catalytic transformation of syngas to high quality liquid fuels. Now, monolithic cobalt‐based heterogeneous catalysts were elaborated through a wet chemistry approach that allows control over nanocrystal shape and crystallographic phase, while at the same time enables heat management. Copper and nickel foams have been employed as supports for the epitaxial growth of hcp‐Co nanowires directly from a solution containing a coordination compound of cobalt and stabilizing ligands. The Co/Cu_foam catalyst was tested for Fischer–Tropsch synthesis in a fixed‐bed reactor, showing stability and significantly superior activity and selectivity towards C5+ compared to a Co/SiO₂‐Al₂O₃ reference catalyst under the same conditions.     

A perturbation result for bounded imaginary powers

We give a new proof of a perturbation result due to J. Prüss and H. Sohr [11]: if an operator A has bounded imaginary powers, then so does A+w (w ≧ 0). Instead of Mellin transform on which the proof in [11] is based, we use the functional calculus for sectorial operators developed in particular by A. McIntosh ([8], [3] and [1]). It turns out that our method gives a more general result than the one used in [11].     

Electrochemical fabrication and characterization of thin films of redox-active molecular wires based on extended Rh-Rh bonded chains

An original electrochemical synthesis of {[Rh4(mu-OOCCH3)4(phen)4]2+}n (1) molecular wire films from a solution of binuclear bridged Rh complexes [Rh2(mu-OOCCH3)2(phen)2(X)2](Y)2 (X = H2O, Y = BF4(-) (2a) and X = CH3CN, Y = BF4(-) (2b)) in MeCN electrolyte is reported. UV-vis spectroscopy and quartz crystal microbalance electrochemical coupled techniques have been used to demonstrate the electrosynthesis process. The resulting polymetallic compound has been characterized on the basis of its physicochemical properties, which have been compared with those of a chemically synthesized sample. Furthermore, according to EPR, 1H NMR and electrochemical behaviour, the mechanism of the oxidation of this polymetallic wire, containing mixed valent rhodium centers and alternatively acetate bridged Rh-Rh bonds, has been investigated in detail.     

Analysis of high molecular mass proteins larger than 150 kDa using cyanogen bromide cleavage and conventional 2-DE

Proteomic approaches including high-resolution 2-DE are providing the tools needed to discover disease-associated biomarkers in complex biological samples. Although 2-DE is an extremely powerful approach to analyze the proteome, the separation of proteins with extreme molecular masses still remains an issue requiring improvement. Because high molecular mass (HMM) proteins larger than 150 kDa have already been observed to be differentially expressed in several pathologies such as cancer, we developed an original strategy to analyze this part of the proteome that is not easily separated by 2-DE in polyacrylamide gels. This strategy is based on the 2-DE separation of cyanogen bromide (CNBr) fragments of purified HMM protein fractions, and combines techniques including SEC fractionation, TCA precipitation, CNBr cleavage, 2-DE and MS analysis. The method was first tested on a model protein, the BSA. Preliminary results obtained using colonic tissues led to the identification of six HMM proteins with M(r) comprised between 163 and 533 kDa in their reduced state. These results demonstrated that our CNBr/2-DE approach should provide a powerful tool for identification of new biomarkers larger than 150 kDa.     

Observation and calculation of the Cs2 2 3Delta(1g) and b 3Pi(0u) states

The Cs(2) 2 (3)Delta(1g) and b (3)Pi(0u) states have been observed by infrared-infrared double resonance spectroscopy for the first time. 221 2 (3)Delta(1g)<--A (1)Sigma(u) (+)<--X (1)Sigma(g) (+) double resonance lines have been assigned to transitions into the 2 (3)Delta(1g) v=6-13 vibrational levels. Resolved fluorescence into the b (3)Pi(0u) v(')=0-48 levels has been recorded. Molecular constants and potential energy curves are determined by the global fit of the entire set of the experimental data. Theoretical potential energy curves of the 2 (3)Delta(g) and b (3)Pi(u) states have been determined in the framework of the pseudopotential method and are compared with the experimental results.     

Thermodynamics of hydrophobic interaction chromatography of acetyl amino acid methyl esters

Thermodynamic analysis of hydrophobic interaction chromatography of amino acid methyl esters showed entropy-driven adsorption, consistent with solvophobic theory, except for phenyl ester on the Toyopearl resins. All esters adsorbed more strongly to the Toyopearl resins, including the polymethacrylate base matrix, than to Butyl Sepharose. Enthalpy changes were more favorable with the former, explaining the retention difference between Toyopearl Butyl and Butyl Sepharose. An enthalpy change versus heat capacity change plot showed Van der Waals interactions predominantly with the resin matrix. Literature data revealed the same effect for dansylamino acids, shown by isothermodynamic temperature analysis to adsorb more entropically than the esters.     

Structure, microstructure, and size dependent catalytic properties of nanostructured ruthenium dioxide

Nanostructured powders of ruthenium dioxide RuO₂ were synthesized via a sol gel route involving acidic solutions with pH varying between 0.4 and 4.5. The RuO₂ nanopowders were characterized by X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM). Rietveld refinement of mean crystal structure was performed on RuO₂ nanopowders and crystallized standard RuO₂ sample. Crystallite sizes measured from X-ray diffraction profiles and TEM analysis varied in the range of 4-10 nm, with a minimum of crystallite dimension for pH=1.5. A good agreement between crystallite sizes calculated from Williamson Hall approach of X-ray data and from direct TEM observations was obtained. The tetragonal crystal cell parameter (a) and cell volumes of nanostructured samples were characterized by values greater than the values of standard RuO₂ sample. In addition, the [Ru-O₆] oxygen octahedrons of rutile structure also depended on crystal size. Catalytic conversion of methane by these RuO₂ nanostructured catalysts was studied as a function of pH, catalytic interaction time, air methane composition, and catalysis temperature, by the way of Fourier transform infrared (FTIR) spectroscopy coupled to homemade catalytic cell. The catalytic efficiency defined as FTIR absorption band intensities I(CO₂) was maximum for sample prepared at pH=1.5, and mainly correlated to crystallite dimensions. No significant catalytic effect was observed from sintered RuO₂ samples.