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Reactive stepping

Sanjib K Shrestha, Liliia M Kril, Keith D Green, Stefan Kwiatkowski, Vitaliy M Sviripa, Justin R Nickell, Linda P Dwoskin, David S Watt, Sylvie Garneau-Tsodikova
The emergence of multidrug-resistant bacterial and fungal strains poses a threat to human health that requires the design and synthesis of new classes of antimicrobial agents. We evaluated bis(N-amidinohydrazones) and N-(amidino)-N'-aryl-bishydrazones for their antibacterial and antifungal activities against panels of Gram-positive/Gram-negative bacteria as well as fungi. We investigated their potential to develop resistance against both bacteria and fungi by a multi-step resistance-selection method, explored their potential to induce the production of reactive oxygen species, and assessed their toxicity...
October 10, 2016: Bioorganic & Medicinal Chemistry
Salma Al-Karmi, Silvia A Albu, Alyssa Vito, Nancy Janzen, Shannon Czorny, Laura Banevicius, Max Nanao, Jon Zubieta, Alfredo Capretta, John F Valliant
Hydrocyanine dyes are sensitive "turn-on" type optical probes that can detect reactive oxygen species (ROS). We have developed a method to prepare an 18F-labeled hydrocyanine dye as a multi-modal PET and optical "turn-on" probe. A commercially available NIR dye was modified with a fluorinated prosthetic group that did not alter its ROS sensing properites in the presence of superoxide and hydroxyl radicals. The 18F-labeled analogue was produced using a single step terminal fluorination procedure. PET imaging and quantitative in vivo biodistribution studies indicated this novel probe had remarkably different pharmacokinetics compared to the oxidized cyanine analogue...
October 21, 2016: Chemistry: a European Journal
Simon Maher, Fred P M Jjunju, Deidre E Damon, Hannah Gorton, Yosef S Maher, Safaraz U Syed, Ron M A Heeren, Iain S Young, Stephen Taylor, Abraham K Badu-Tawiah
Metaldehyde is extensively used worldwide as a contact and systemic molluscicide for controlling slugs and snails in a wide range of agricultural and horticultural crops. Contamination of surface waters due to run-off, coupled with its moderate solubility in water, has led to increased concentration of the pesticide in the environment. In this study, for the first time, rapid analysis (<~1 minute) of metaldehyde residues in water is demonstrated using paper spray mass spectrometry (PS-MS). The observed precursor molecular ions of metaldehyde were confirmed from tandem mass spectrometry (MS/MS) experiments by studying the fragmentation patterns produced via collision-induced dissociation...
October 21, 2016: Scientific Reports
Daniela Damasceno, Martín Pérez Andrés, Wouter Bl van den Bossche, Juan Flores-Montero, Sandra de Bruin, Cristina Teodosio, Jacques Jm van Dongen, Alberto Orfao, Julia Almeida
Although major steps have been recently made in understanding the role of the distinct subsets of dendritic cells (DC)/antigen-presenting cells (APC), further studies are required to unravel their precise role, including in-depth immunophenotypic characterisation of these cells. Here, we used eight-colour flow cytometry to investigate the reactivity of a panel of 72 monoclonal antibodies (including those clustered in seven new Cluster of Differentiation, CD) on different subsets of APC in peripheral blood (PB) samples from five healthy adults...
September 2016: Clinical & Translational Immunology
Seung Kyum Kim, Joshua J Avila, Michael P Massett
Understanding the genetic influence on vascular reactivity is important for identifying genes underlying impaired vascular function. The purpose of this study was to characterize the genetic contribution to intrinsic vascular function and to identify loci associated with phenotypic variation in vascular reactivity in mice. Concentration response curves to phenylephrine (PE), potassium chloride (KCl), acetylcholine (ACh), and sodium nitroprusside (SNP) were generated in aortic rings from male mice (12-wk old) from 27 inbred mouse strains...
October 7, 2016: Physiological Genomics
Johannes G de Vries
Several strategies can be chosen to convert renewable resources into chemicals. In this account, I exemplify the route that starts with so-called platform chemicals; these are relatively simple chemicals that can be produced in high yield, directly from renewable resources, either via fermentation or via chemical routes. They can be converted into the existing bulk chemicals in a very efficient manner using multistep catalytic conversions. Two examples are given of the conversion of sugars into nylon intermediates...
October 20, 2016: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Tong Zhang, Chunqiang Zhang, Xiaomei Fan, Ruilan Li, Jiaxin Zhang
C-type natriuretic peptide (CNP) has been considered as a physiological meiotic inhibitor that stimulates the cGMP production by cumulus cell natriuretic peptide receptor 2 (NPR2), which inhibits oocyte phosphodiesterase type 3 activity and increases cAMP. In this study, we explored the effect of CNP pretreatment on the in vitro maturation (IVM) of bovine oocytes by examining changes in cleavage rate, blastocyst formation, mitochondrial DNA (mtDNA) copy number, reactive oxygen species (ROS) level, glutathione (GSH) content, and redox state...
October 19, 2016: In Vitro Cellular & Developmental Biology. Animal
Anjali P Kusumbe
The vasculature of the skeletal system regulates osteogenesis and hematopoiesis, in addition to its primary function as a transportation network. Recent studies suggest that the vasculature in bone regulates multiple steps involved in the metastatic cascade. Matrix and growth factor abundant vascular microenvironments in bone not only provide a fertile soil for the metastatic growth but also support the dormancy of Disseminated Tumour Cells (DTCs). Interestingly, vasculature also seems to direct the reactivation of dormant DTCs...
September 2016: Journal of Bone Oncology
Ming Wang, Zhijian Huang
By using a diaryliodonium salt as a benzyne precursor, a transition metal-free approach for N-arylation of secondary amides is developed. This novel benzyne precursor, which can be prepared easily by a one step process from an aryl iodide, shows different reactivities with previous benzyne precursors in the N-arylation reaction. Mechanistic studies confirm the involvement of benzyne species (generated in situ from the diaryliodonium salts) as key intermediates.
October 19, 2016: Organic & Biomolecular Chemistry
Jihye Jung, Tibor Czabany, Birgit Wilding, Norbert Klempier, Bernd Nidetzky
The enzyme QueF catalyzes a four-electron reduction of a nitrile group into an amine, the only reaction of this kind known in biology. In nature, QueF converts 7-cyano-7-deazaguanine (preQ0) into 7-aminomethyl-7-deazaguanine (preQ1) for the biosynthesis of the tRNA-inserted nucleoside queuosine. The proposed QueF mechanism involves a covalent thioimide adduct between preQ0 and a cysteine nucleophile in the enzyme, and this adduct is subsequently converted into preQ1 in two NADPH-dependent reduction steps. Here, we show that the Escherichia coli QueF binds preQ0 in a strongly exothermic process (∆H = -80...
October 17, 2016: Journal of Biological Chemistry
Marino Börjesson, Toni Moragas, Daniel Gallego, Ruben Martin
The recent years have witnessed the development of metal-catalyzed reductive carboxylation of organic (pseudo)halides with CO2 as C1 source, representing potential powerful alternatives to existing methodologies for preparing carboxylic acids, privileged motifs in a myriad of pharmaceuticals and molecules displaying significant biological properties. While originally visualized as exotic cross-coupling reactions, a close look into the literature data indicates that these processes have become a fertile ground, allowing for the utilization of a variety of coupling partners, even with particularly challenging substrate combinations...
October 7, 2016: ACS Catalysis
Lyndsey M Hornbuckle, J Derek Kingsley, Michael R Kushnick, Robert J Moffatt, Emily M Haymes, Rebecca Miles, Tonya Toole, Lynn B Panton
This study examined the effects of a 12-month walking intervention in overweight/obese, low socioeconomic women. Forty-six women (48.2 ± 8.0 years) entered the study. Outcomes included weight, waist and hip circumferences, body mass index (BMI), blood pressure, glycosylated hemoglobin, blood lipids, fibrinogen, and high-sensitivity C-reactive protein (hsCRP). Both intention-to-treat analyses in all participants and group analyses in study completers only (3K group = increased steps/day by ≥3,000; No Δ group = did not increase steps/day by ≥3,000) were conducted...
2016: Clinical Medicine Insights. Women's Health
Maria-Luisa Alegre, Fadi G Lakkis, Adrian E Morelli
Transplantation of solid organs between genetically distinct individuals leads, in the absence of immunosuppression, to T cell-dependent transplant rejection. Activation of graft-reactive T cells relies on the presentation of transplant-derived antigens (intact donor MHC molecules or processed peptides on host MHC molecules) by mature dendritic cells (DCs). This review focuses on novel insights regarding the steps for maturation and differentiation of DCs that are necessary for productive presentation of transplant antigens to host T cells...
October 12, 2016: Trends in Immunology
Luis Carlos de Vicente Poutás, Marta Castiñeira Reis, Roberto Sanz, Carlos Silva López, Olalla Nieto Faza
We propose a novel mechanism for the deoxydehydration (DODH) reaction of glycols catalyzed by a [Bu4N][VO2(dipic)] complex (dipic = pyridine-2,6-dicarboxylate) using triphenylphosphine as a reducing agent. Using density functional theory, we have confirmed that the preferred sequence of reaction steps involves reduction of the V(V) complex by phosphine, followed by condensation of the glycol into a [VO(dipic)(-O-CH2CH2-O-)] V(III) complex (6), which then evolves to the alkene product, with recovery of the catalyst...
October 14, 2016: Inorganic Chemistry
Ibrahim Saana Amiinu, Jian Zhang, Zongkui Kou, Xiaobo Liu, Owusu Kwadwo Asare, Huang Zhou, Kun Cheng, Haining Zhang, Liqiang Mai, Mu Pan, Shichun Mu
3D graphene-based materials offer immense potentials to overcome the challenges related to the functionality, performance, cost, and stability of fuel cell electrocatalysts. Herein, a nitrogen (N) and sulfur (S) dual-doped 3D porous graphene catalyst is synthesized via a single-row pyrolysis using biomass as solitary source for both N and S, and a structure directing agent. The thermochemical reaction of biomass functional groups with graphene oxide facilitates in situ generation of reactive N and S species, stimulating the graphene layers to reorganize into a trimodal 3D porous assembly...
October 14, 2016: ACS Applied Materials & Interfaces
Steven Martens, Jos Van den Begin, Annemieke Madder, Filip E Du Prez, Pieter Espeel
Long, multifunctional sequence-defined oligomers were obtained on solid support from a protecting-group-free two-step iterative protocol, based on the inherent reactivity of a readily available molecule containing an isocyanate and a thiolactone group. Aminolysis of the latter entity with an amino alcohol liberates a thiol that reacts with an acrylate, present in the same medium. Subsequently, a thiolactone can be reinstated by means of an α-isocyanato-γ-thiolactone. Different acrylic compounds were used to incorporate diverse functionalities in the oligomers, which were built up to the level of decamers...
October 14, 2016: Journal of the American Chemical Society
Urooj Quezon Amjad, Jeanne Luh, Rachel Baum, Jamie Bartram
First developed by the World Health Organization, and now used in several countries, water safety plans (WSPs) are a multi-step, preventive process for managing drinking water hazards. While the beneficial impacts of WSPs have been documented in diverse countries, how to successfully implement WSPs in the United States remains a challenge. We examine the willingness and ability of water utility leaders to implement WSPs in the US state of North Carolina. Our findings show that water utilities have more of a reactive than preventive organizational culture, that implementation requires prioritization of time and resources, perceived comparative advantage to other hazard management plans, leadership in implementation, and identification of how WSPs can be embedded in existing work practices...
October 2016: Journal of Water and Health
Matthew Y H Tang, Ho Cheung Shum
We present a wash-free high-sensitivity immunoassay of C-reactive proteins with droplet microfluidics. Microbeads are encapsulated within droplets for the immunoassay, and the droplets are scanned by a fluorescence detection platform to quantify the amount of proteins captured on the microbeads. The limit of detection determined by our platform is 0.01 μg mL(-1), which is ten times more sensitive than conventional high-sensitivity C-reactive protein assays. With the decrease in diffusion distance within droplets, the immunoassay requires only half of the time required for similar conventional approaches...
October 14, 2016: Lab on a Chip
Zhongbao Jian, Laura Falivene, Giusi Boffa, Sheila Ortega Sánchez, Lucia Caporaso, Alfonso Grassi, Stefan Mecking
A single-step route to telechelic polyethylene (PE) is enabled by selective insertion polymerization. Pd(II) -catalyzed copolymerization of ethylene and 2-vinylfuran (VF) generates α,ω-di-furan telechelic polyethylene. Orthogonally reactive exclusively in-chain anhydride groups are formed by terpolymerization with carbic anhydride. Combined experimental and theoretical DFT studies reveal the key for this direct approach to telechelics to be a match of the comonomers' different electronics and bulk. Identified essential features of the comonomer are that it is an electron-rich olefin that forms an insertion product stabilized by an additional interaction, namely a π-η(3) interaction for the case of VF...
October 13, 2016: Angewandte Chemie
Tobias Heurich, Vitaly Nesterov, Gregor Schnakenburg, Zheng-Wang Qu, Stefan Grimme, Khatera Hazin, Derek P Gates, Marianne Engeser, Rainer Streubel
Facile access to [W(CO)5 (Ph2 P-OTEMP)] is used to initiate a study on the generation, properties, and reactions of transient phosphanoxyl complexes [MLn (R2 PO)], the first example of which could be trapped via heterocoupling with the trityl radical. It is also demonstrated that the phosphorus nitroxyl complex acts as radical initiator in the polymerization of styrene. The quest for P-O versus O-N bond homolysis, as well as the initial steps of the polymerization were studied by DFT methods.
October 13, 2016: Angewandte Chemie
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