Simultaneous lipidomic analysis of three families of bioactive lipid mediators leukotrienes, resolvins, protectins and related hydroxy-fatty acids by liquid chromatography/electrospray ionisation tandem mass spectrometry

Bioactive lipid mediators derived from polyunsaturated fatty acids (PUFA) exhibit a range of tissue- and cell-specific activities in many physiological and pathological processes. Electrospray ionisation tandem mass spectrometry coupled to liquid chromatography (LC/ESI-MS/MS) is a sensitive, versatile analytical methodology for the qualitative and quantitative analysis of lipid mediators. Here we present an LC/ESI-MS/MS assay for the simultaneous analysis of twenty mono- and poly-hydroxy-fatty acid derivatives of linoleic, arachidonic, eicosapentaenoic and docosahexaenoic acids. The assay was linear over the concentration range 1-100 pg/microL, whilst the limits of detection and quantitation were 10-20 and 20-50 pg, respectively. The recovery of the extraction methodology varied from 76-122% depending on the metabolite. This system is useful for profiling a range of biochemically related potent mediators including the newly discovered resolvins and protectins, and their precursor hydroxyeicosapentaenoic and hydroxydocosahexaenoic acids, and, consequently, advance our understanding of the role of PUFA in health and disease.     

Identification of endogenous resolvin E1 and other lipid mediators derived from eicosapentaenoic acid via electrospray low-energy tandem mass spectrometry: spectra and fragmentation mechanisms

Resolvin E1 (RvE1, 5S,12R,18R-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid) is a novel anti-inflammatory lipid mediator recently found in humans, mice, and fish in vivo. To identify endogenous RvE1 and other eicosapentaenoic acid (EPA)-derived lipid mediators using electrospray low-energy collision-induced dissociation tandem mass spectrometry (MS/MS), the MS/MS product ion spectra of these compounds were correlated with their structures, and the MS/MS fragmentation mechanisms were studied. Deuterium labeling confirmed the proposed correlations and the fragmentation mechanisms. beta-cleavage was observed for RvE1, and beta and gamma cleavages were seen for leukotriene B5; however, alpha-cleavage was more common. The positions and numbers of hydroxyls and double bonds of these lipid mediators can be deduced from the MS/MS spectra. The MS/MS fragmentation generating chain-cut ions involved beta-ene, gamma-ene, or alpha-H-beta-ene rearrangement, depending on the specific structure. The m/z value of a detected chain-cut ion from RvE1 or from an EPA-derived product is equal to the corresponding hypothetical homolytic segment (cc, cm, mc, or mm) with the addition or extraction of up to two hydrogen atoms (H) from hydroxyls or an alpha-carbon; namely, the m/z value of an alpha-cleavage-generated ion is equal to [cc+H], [cm-2H], [mc-H], or [mm]. Wideband activation increased the signal intensities of chain-cut ions, and therefore was better for trace analysis of RvE1 in biological samples. RvE1, LTB5, PGE3, and other EPA-derived lipid mediators were found in trout brain or head-kidney via this approach on the basis of MS/MS spectra and fragmentation mechanisms. Negative ion electrospray low-collision-energy MS/MS spectra provide adequate data to elucidate and identify the structures of RvE1 and other EPA-derived lipid mediators at levels below a few picomoles in trout samples.     

Catalytic Synthesis of 2-Methyl-1,4-Naphthoquinone (Vitamin K3) Over Silica-Supported Aminomethyl Phosphine-Ru(II), Pd(II), and Co(II) Complexes

Ru(II), Pd(II), and Co(II) complexes of the free ditertiary aminomethylphosphine ligand, N,N-bis(diphenylphosphinomethyl)aminopropyltriethoxysilane [(EtO)₃Si(CH₂)₃ N(CH₂PPh₂)₂] (DIPAPTES), and its SiO₂-DIPAPES have been synthesized under a nitrogen atmosphere using Schlenk techniques. All the complexes were used as catalysts for the oxidation of 2-methyl naphthalene (2MN) to give 2-methyl-1,4-naphthoquinone (vitamin K₃, menadione, 2MNQ) in the presence of hydrogen peroxide as a clean and cheap oxidant. The catalytic synthesis of vitamin K₃ was investigated using both homogeneous catalysis with free complexes and heterogeneous catalysis with silica-supported complexes. [(DIPAPTES)PdCl₂] and its silica-supported form showed the best catalytic activity for the selective oxidation of 2-methyl naphthalene to 2-methyl-1,4-naphtoquinone compared to the other metal complexes. 2MNQ yield reached 52.26% with the 2MN conversion of 90.52% using complex [(DIPAPTES)PdCl₂] and 58.59% with the 2MN conversion of 99.56% using the silica supported [SiO₂(DIPAPES)PdCl₂] complex for 1 h. Recycling was investigated for the silica-supported Pd(II) complex and compared with the classical production of vitamin K₃.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Policies utilizing tactical inventory for service-differentiated customers

We consider a manufacturer serving two customer classes where one wants the item immediately and the second receives a discount to accept a delay. We show that an (S,R,B) base-stock policy is optimal under differentiation and non-differentiation where S, R, and B are the order-up-to, reserve-up-to, and backlog-up-to amounts.     

Laminar flow modelling of a thermosyphon loop at specified wall temperatures

A thermosyphon loop is analyzed in this study by use of numerical and experimental techniques. A rectangular loop was constructed using copper pipe and the sections which were heated or cooled were designed as concentric tube heat exchangers. Hot or cold water was circulated outside of these sections, and both the surface temperatures and heat transferred to and from the loop were measured. Within the numerical study both the momentum and energy equations were also solved using a SIMPLEX algorithm. Numerical results were obtained for laminar flow within the circuit when there was uniform wall temperature in the vertically heated and cooled sections of the thermosyphon. The two-dimensional numerical model provided results which agree with those found experimentally from the thermosyphon loop. In addition, a simulation model was constructed using a correlation included both the Grashof and Prandtl numbers to evaluate heat transfer through a thermosyphon loop.     

Simple and accurate model for voltage-dependent resistance of metallic carbon nanotube interconnects: An ab initio study

In this work, development of a voltage dependent resistance model for metallic carbon nanotubes is aimed. Firstly, the resistance of metallic carbon nanotube interconnects are obtained from ab initio simulations and then the voltage dependence of the resistance is modeled through regression. Self-consistent non-equilibrium Green's function formalism combined with density functional theory is used for calculating the voltage dependent resistance of metallic carbon nanotubes. It is shown that voltage dependent resistances of carbon nanotubes can be accurately modeled as a polynomial function which enables rapid integration of carbon nanotube interconnect models into electronic design automation tools.     

Resolvin D3 and Aspirin-Triggered Resolvin D3 Are Potent Immunoresolvents

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Highlights? RvD3 accumulates in late inflammation resolution ? Aspirin triggers biosynthesis of RvD3 17R-epimer (AT-RvD3) that is proresolving ? Complete stereochemistry of RvD3 and AT-RvD3 are established ? RvD3 and AT-RvD3 govern leukocyte functions and local inflammatory responses     

The effect of radiolabeled antibiotics on biofilm and microorganism within biofilm

Journal of Radioanalytical and Nuclear Chemistry - The aim of this study was to investigate the 131I and 127I labeled linezolid and moxifloxacin effects of minimum inhibitory concentration, and...