bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arginine dipeptides affect insulin aggregation in a pH‐ and ionic strength‐dependent manner
Authors: Nuhu Mariam M. , Curtis Robin 
Published: January 2015

AbstractSolutions containing arginine or mixtures of arginine and other amino acids are commonly used for protein liquid formulations to overcome problems such as high viscosities, aggregation, and phase separation. The aim of this work is to examine whether the stabilizing properties of arginine can be improved by incorporating the amino acid into a dipeptide. A series of arginine‐containing dipeptides have been tested for their ability to suppress insulin aggregation over a range of pH and ionic strength. The aggregation is monitored at room temperature using a combination of turbidimetry and light scattering for solutions at pH 5.5 or 3.7, whereas thermal‐induced aggregation is measured at pH 7.5. In addition, intrinsic fluorescence has been used to quantify additive binding to insulin. The dipeptide diArg is the most effective additive in solutions at pH 5.5 and 3.7, whereas the dipeptide Arg‐Phe almost completely eliminates thermally‐induced aggregation of insulin at pH 7.5 up to temperature of 90°C. Insulin has been chosen as a model system because the molecular forces controlling its aggregation are well known. From this understanding, we are able to provide a molecular basis for how the various dipeptides affect insulin aggregation.
A rapid and sensitive LC‐MS/MS method for quantification of 3,29‐dibenzoyl rarounitriol in rat plasma: application to a pharmacokinetic study
Authors: Zhao Chengliang , Zhang Nan , Chen Bin , Song Youxin , Zhu Naiqiang , Zhao Long , Liu Changjian , Meng Xiangwei 
Published: January 2015

AbstractA rapid, sensitive and high‐throughput liquid chromatography–tandem mass spectrometry was established and validated to assay the concentrations of 3,29‐dibenzoyl rarounitriol in rat plasma. Plasma samples were processed by liquid–liquid extraction with ethyl acetate and separated on a Hypersil Gold C18 column (50 × 4.6 mm, 3 µm) at an isocratic flow rate of 0.5 mL/min using methanol–10 mm ammonium acetate–formic acid (90:10:0.1, v/v/v) as mobile phase. The total run time was 5 min for each sample. MS/MS detection was accomplished in selected reaction monitoring mode with positive electrospray ionization. The calibration curve was linear over the concentration range of 0.125–50 ng/mL with lower limit of quantification of 0.125 ng/mL. The intra‐ and inter‐day precisions were <10.1% in terms of coefficient of variation, and the accuracy was within ±11.7% in terms of relative error. The developed method was successfully applied to a pharmacokinetic study of 3,29‐dibenzoyl rarounitriol following intragastric administration of 3.65 mg/kg to Wistar rats. Copyright © 2015 John Wiley & Sons, Ltd.
Placenta accreta: adherent placenta due to Asherman syndrome
Authors: Engelbrechtsen Line , Langhoff‐Roos Jens , Kjer Jens Joergen , Istre Olav 
Published: January 2015

Key Clinical MessageIt is important to be aware of the risk of abnormally invasive placenta in patients with a history of Asherman syndrome and uterine scarring. A prenatal diagnosis by ultrasonography is useful when planning of mode of delivery.
Balancing the Stability–Activity Trade‐Off by Fine‐Tuning Dehalogenase Access Tunnels
Authors: Liskova Veronika , Bednar David , Prudnikova Tatyana , Rezacova Pavlina , Koudelakova Tana , Sebestova Eva , Smatanova Ivana Kuta , Brezovsky Jan , Chaloupkova Radka , Damborsky Jiri 
Published: January 2015

AbstractA variant of the haloalkane dehalogenase DhaA with greatly enhanced stability and tolerance of organic solvents but reduced activity was created by mutating four residues in the access tunnel. To create a stabilised enzyme with superior catalytic activity, two of the four originally modified residues were randomised. The resulting mutant F 176 G exhibited 32‐ and 10‐times enhanced activity towards 1,2‐dibromoethane in buffer and 40 % DMSO, respectively, upon retaining high stability. Structural and molecular dynamics analyses demonstrated that the new variant exhibited superior activity because the F 176 G mutation increased the radius of the tunnel’s mouth and the mobility of α‐helices lining the tunnel. The new variant’s tunnel was open in 48 % of trajectories, compared to 58 % for the wild‐type, but only 0.02 % for the original four‐point variant. Delicate balance between activity and stability of enzymes can be manipulated by fine‐tuning the diameter and dynamics of their access tunnels.
Characterization and Reactivity of a Terminal Nickel(III)–Oxygen Adduct
Authors: Pirovano Paolo , Farquhar Erik R. , Swart Marcel , Fitzpatrick Anthony J. , Morgan Grace G. , McDonald Aidan R. 
Published: January 2015

AbstractHigh‐valent terminal metal–oxygen adducts are hypothesized to be the potent oxidizing reactants in late transition metal oxidation catalysis. In particular, examples of high‐valent terminal nickel–oxygen adducts are scarce, meaning there is a dearth in the understanding of such oxidants. A monoanionic NiII‐bicarbonate complex has been found to react in a 1:1 ratio with the one‐electron oxidant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate, yielding a thermally unstable intermediate in high yield (ca. 95 %). Electronic absorption, electronic paramagnetic resonance, and X‐ray absorption spectroscopies and density functional theory calculations confirm its description as a low‐spin (S=1/2), square planar NiIII–oxygen adduct. This rare example of a high‐valent terminal nickel–oxygen complex performs oxidations of organic substrates, including 2,6‐di‐tert‐butylphenol and triphenylphosphine, which are indicative of hydrogen atom abstraction and oxygen atom transfer reactivity, respectively.
Photocatalytic Carbon Dioxide Reduction with Rhodium‐based Catalysts in Solution and Heterogenized within Metal–Organic Frameworks
Authors: Chambers Matthew B. , Wang Xia , Elgrishi Noémie , Hendon Christopher H. , Walsh Aron , Bonnefoy Jonathan , Canivet Jérôme , Quadrelli Elsje Alessandra , Farrusseng David , Mellot‐Draznieks Caroline , Fontecave Marc 
Published: January 2015

AbstractThe first photosensitization of a rhodium‐based catalytic system for CO2 reduction is reported, with formate as the sole carbon‐containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H2‐storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post‐synthetic linker exchange, and characterization of a new metal–organic framework (MOF) Cp*Rh@UiO‐67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF‐based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of ∼10 % molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H2. There is no precedent for a MOF catalyzing the latter reaction so far.
Metabolic syndrome: an ill wind that blows some good?
Authors: Taylor Simeon I. 
Published: January 2015

AbstractIn this issue of the journal, Brima et al. report thought‐provoking research providing a potential evolutionary rationale whereby natural selection might have preserved genes that predispose to metabolic syndrome. When CD‐1 mice were fed a high fat diet, this induced metabolic changes characteristic of metabolic syndrome. In addition, the high fat diet provided substantial protection from lethality due to infection with Trypanosoma cruzi. The authors hypothesize that the same genes predispose to both metabolic syndrome and protection against infectious disease. Thus, the selective advantage of not dying from infectious disease implicitly provides selective pressure predisposing to metabolic syndrome. This hypothesis follows a similar line of reasoning that has provided explanations for the survival of the HbS mutation for sickle cell disease and renal disease‐associated genetic variants in apolipoprotein L1. Variants in these two genes provide protection from malaria and Trypanosoma brucei rhodesiense, respectively. Copyright © 2015 John Wiley & Sons, Ltd.
Six1 is down‐regulated in end‐stage human dilated cardiomyopathy independently of Ezh2
Authors: Tschirner Anika , Palus Sandra , Hetzer Roland , Meyer Rudolf , Anker Stefan D. , Springer Jochen 
Published: January 2015

BackgroundRecently, it was shown that a knock‐out (KO) of the polycomb histone methyltransferase Ezh2 leads to cardiac hypertrophy in mice, which was driven by the homeodomain transcription factor Six1. Here, we analyzed the expression of Six1 and its regulating factor Ezh2 in cardiac tissue of patients with end‐stage dilative cardiomyopathy (DCM).MethodsTissue samples of patients with end‐stage DCM (n = 35) were compared with controls (n = 12) for the protein expression of Ezh1, Ezh2, Six1, and a marker of protein expression p70S6K.ResultsContrary to the Ezh2‐KO mouse model, we found a down‐regulation of Six1 (26%) and an up‐regulation of Ezh2 (76%) in DCM hearts, (both P < 0.05). Expression of Ezh2 and Six1 did not correlate in human tissue (DCM: r2: 0.03, P = 0.31 and donor: r2: 0.05, P = 0.45). Expression of Six1 weakly correlated with left ventricular end‐systolic diameter and fractional shortening. In DCM, Six1 also showed a positive correlation to the expression of the ribosomal protein p70S6K (r: 0.39, P = 0.029), which is involved in protein synthesis. This correlation was not seen in donor tissue, which showed a trend for a negative correlation (r: −0.49, P = 0.08).ConclusionOur data indicate that the Ezh2/Six1 axis might be involved in human DCM. However, Six1 expression may be regulated by factors other than Ezh2, and more research is needed to determine the precise role of Ezh2/Six1 in human DCM.
A Series of Noncentrosymmetric Antimony Sulfides Ln8Sb2S15 (Ln = La, Pr, Nd) – Syntheses, Crystal and Electronic Structures, and NLO Properties
Authors: Zhao Hua‐Jun , Zhou Liu‐Jiang 
Published: January 2015

AbstractA series of noncentrosymmetric sulfides Ln8Sb2S15 (Ln = La, Pr, Nd) were prepared from stoichiometric mixtures of the elements at 1223 K in an evacuated silica tube. The compounds Ln8Sb2S15 with Ln = La and Nd are isostructural to Pr8Sb2S15 and crystallize in the tetragonal noncentrosymmetric space group I41cd. Their structure contains discrete [SbS3]3– trigonal pyramids separated by Ln3+ cations and S2– anions. La8Sb2S15 shows second harmonic generation with intensities 1.2 times that of the commercially used IR NLO (nonlinear optics) material AgGaS2 (at 2.05 μm laser). It exhibits excellent thermal stability up to 663 °C. Studies with UV/Vis–NIR diffuse reflectance spectroscopy show that La8Sb2S15 has an optical gap of around 2.3 eV, and a DFT study indicates a direct band gap with an electronic transfer excitation of S 3p electrons to a La 5d orbital.
Seleno‐methionine decreases biohydrogenation of C18 unsaturated fatty acids in ovine ruminal fluid incubated in vitro with α‐linolenic acid
Authors: Czauderna Marian , Rozbicka‐Wieczorek Agnieszka J. , Więsyk Edyta , Krajewska‐Bienias Katarzyna A. 
Published: January 2015

The influence of seleno‐methionine (Se‐Met) added to an ovine ruminal fluid containing α‐linolenic acid (α‐LNA) on the profile of fatty acids (FA) was investigated. The fluid was incubated in vitro at 39°C under CO2 either alone (the control ruminal fluid; RF) or with α‐LNA (1.67 mg/mL) or with a combination of α‐LNA with either a low (1.25 µg/mL) or high (4.16 µg/mL) concentration of Se as Se‐Met. Tubes with fluids were removed after 0, 6, 12, 18 or 24 h of incubation. α‐LNA in the fluids with/without Se‐Met stimulated the accumulation of C14:0 and C16:0 compared with the RF. The fluids containing Se‐Met reduced the concentration of C18:0 compared with the RF. α‐LNA in the fluids with/without Se‐Met increased concentrations of cis9C14:1, cis9C18:1 and trans11C18:1 compared with the RF and the fluids with Se‐Met. The fluids with α‐LNA and Se‐Met increased the accumulation of trans9trans11cis15C18:3 compared with the fluids with α‐LNA. The fluids with α‐LNA and Se‐Met decreased the biohydrogenation to C18:0 compared with the RF. Se‐Met in the fluids elevated the concentration of trans11C18:1 and lowered the capacity of the biohydrogenation to C18:0 in the fluids incubated for 24 h. Added Se‐Met affected the FA profile in incubated fluids.Practical applicationsSelenium and polyunsaturated fatty acids n‐3 (PUFAn‐3) are very important for human health and nutrition. Recent studies documented that a higher content of mono‐conjugated isomers of α‐linolenic acid (α‐LNA) in diets reduced the abundance of PUFAn‐3 in the brain, liver and heart of experimental animals. Due to the increasing world population, overfishing of the seas and usually low concentrations of PUFAn‐3 and essential trace elements (like selenium) in animal products, there is a demand for better methods of feeding livestock. Considering the above, it was desirable to study the extent to which dietary seleno‐compounds (like seleno‐methionine) may contribute to concentrations of mono‐conjugated α‐LNA (C‐α‐LNA) isomers, as C‐α‐LNA isomers may perturb the PUFA balance (or imbalance) in tissues of animals and humans. Moreover, further studies are needed to determine if dietary seleno‐compounds, α‐LNA and C‐α‐LNA isomers also induce changes in concentrations of fatty acids, especially PUFAn‐3, in tissues of lambs.Seleno‐methionine has an influence on the concentrations of fatty acids, especially unsaturated fatty acids, in in vitro incubated ovine ruminal fluid, irrespective of the presence of α‐linolenic acid. Seleno‐methionine added to the incubated fluids affects the capacity of the bacterial isomerases and modified activities of ruminal bacteria. The simultaneous addition of α‐linolenic acid and Se‐Met to the ruminal fluids decreased the yield of final biohydrogenation to C18:0 in comparison with the in vitro incubated control fluids.
Iron‐catalyzed depolymerizations of silicones with hexanoic anhydride provide a potential recycling method for end‐of‐life polymers
Authors: Weidauer Maik , Heyder Benedict , Woelki Daniel , Tschiersch Moritz , Köhler‐Krützfeldt Angela , Enthaler Stephan 
Published: January 2015

One of the great impacts of polymeric materials is the matter of the accumulation of huge amounts of end‐of‐life polymers. At the present date, waste management is based primarily on landfills, thermal recycling, and down‐cycling, while only a small part of the waste is subjected to feedstock recycling. In more detail, polymers are converted to low‐molecular weight synthons by depolymerization and a subsequent polymerization process creates new high‐quality polymers. Widely‐used polymers in modern society are polysiloxanes (silicones) and recycling is still an issue. In this regard, we present herein the depolymerization of polysiloxanes, applying a fatty acid anhydride as the depolymerization reagent. In the presence of catalytic amounts of iron salts, low‐molecular weight products with the motif RC(O)(OSiMe2)mOC(O)R (R = n‐pentyl, m = 1–4) were observed. Notably, the reaction of RC(O)(OSiMe2)mOC(O)R with water revealed the formation of octamethylcyclotetra‐ and decamethylcyclopentasiloxanes and the corresponding fatty acid as side product, which can potentially be reconverted to the fatty acid anhydride. Interestingly, a recycling of the polymer and the depolymerization reagent is feasible.Practical applications: Huge amounts of end‐of‐life polymers are produced by our society and several methodologies for waste treatment have been established so far. One interesting recycling approach can be the conversion of end‐of‐life polymers, via depolymerization, into useful commodities, which can be applied as feedstock for new materials. Taking these aspects into account we studied the depolymerization of end‐of‐life polysiloxanes, applying cheap and abundant iron salts as a precatalyst and a fatty acid anhydride as a depolymerization reagent, which can be easily accessed from renewable resources, hence avoiding the use of fossil fuels‐based chemicals. As major products RC(O)(OSiMe2)mOC(O)R were obtained, these can be utilized as starting material for new polysiloxanes. Moreover, the simple operation of the reaction (e.g., no protection atmosphere, solvent free) makes this recycling method attractive for large scale applications.In the present work, the straightforward iron‐catalyzed depolymerization of end‐of‐life polysiloxanes with a fatty acid anhydride has been studied. Depolymerization products RC(O)O(SiMe2)mOC(O)R have been produced, which can be appropriate starting materials for new polymers.
Unprotected Xylose‐Derived Nitrone in Stereodivergent Synthesis of 4‐Hydroxypiperidine Enantiomers: Weak Lewis Acid Induced Alteration of Stereochemistry in 1,3‐Dipolar Cycloaddition
Authors: Rowicki Tomasz , Malinowski Maciej , Gryszel Maciej , Czerwińska Karolina , Madura Izabela , Mironiuk‐Puchalska Ewa , Koszytkowska‐Stawińska Mariola , Sas Wojciech 
Published: January 2015

AbstractA one‐pot, two‐step synthesis of chiral 7‐oxa‐1‐azabicyclo[2.2.1]heptane derivatives from unprotected D‐xylose was achieved by an intramolecular 1,3‐dipolar cycloaddition of the N‐(γ‐alkenyl)‐substituted nitrone intermediate. The stereochemical course of the cycloaddition was altered by the addition of an achiral Lewis acid. The bicyclic byproducts were employed in a concise synthesis of two new enantiomeric piperidine‐type iminosugars.
4,4,8,8‐Tetranitroadamantane‐2,6‐diyl Dinitrate: A High‐Density Energetic Material
Authors: Ling Yifei , Ren Xiaoli , Lai Weipeng , Luo Jun 
Published: January 2015

AbstractThe novel high‐performance energetic material 4,4,8,8‐tetranitroadamantane‐2,6‐diyl dinitrate has been synthesized and fully characterized. The synthetic strategy features the construction of the adamantane skeleton with different functional groups at adjacent methylene carbon atoms to overcome the problems associated with the ortho effect and steric crowding, and is amenable to the synthesis of other polynitroadamantanes. The experimentally determined physical properties as well as the calculated detonation properties indicate that this compound exhibits high thermal stability (220 °C), high density (1.852 g cm–3), and excellent detonation velocities (8529 m s–1) and pressures (33.43 GPa).
Enzymatic Oxygen Microsensor Based on Bilirubin Oxidase Applied to Microbial Fuel Cells Analysis
Authors: Grattieri Matteo , Babanova Sofia , Santoro Carlo , Guerrini Edoardo , Trasatti Stefano PM , Cristiani Pierangela , Bestetti Massimiliano , Atanassov Plamen 
Published: January 2015

AbstractA selective oxygen biosensor based on bilirubin oxidase (BOx) was developed. The sensor was used for determining oxygen profiles in a membraneless, single‐chamber microbial fuel cell (SCMFC), fed with raw wastewater. The linear response of the sensor was optimized by a diffusion layer of silica gel. A computer‐controlled stage was used to obtain accurate and precise measurements. Oxygen concentration in biofilms covering electrodes was measured, showing 3 mg L−1 of O2 in the bulk solution, decreasing to 0 mg L−1 in the cathodic biofilm. The MFC generated power in the range of 0–0.08 mW, associated to the oxygen content.
Toxicity of cobalt–chromium nanoparticles released from a resurfacing hip implant and cobalt ions on primary human lymphocytes in vitro
Authors: Posada Olga M. , Tate R. J. , Grant M. H. 
Published: January 2015

AbstractAdverse tissue responses to prostheses wear particles and released ions are important contributors to hip implant failure. In implant‐related adverse reactions T‐lymphocytes play a prominent role in sustaining the chronic inflammatory response. To further understand the involvement of lymphocytes in metal‐on‐metal (MoM) implant failure, primary human lymphocytes were isolated and treated with cobalt–chromium (Co‐Cr) wear debris and Co ions, individually, and in combination, for 24, 48 and 120 h. There was a significant increase in cell number where debris was present, as measured by the Neutral Red assay. Interleukin‐6 (IL‐6), interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) secretion levels significantly decreased in the presence of metal particles, as measured by ELISA. Interleukin‐2 (IL‐2) secretion levels were significantly decreased by both debris and Co ions. Flow cytometry analysis showed that the metal nanoparticles induced a significant increase in apoptosis after 48‐h exposure. This investigation showed that prolonged exposure (120 h) to metal debris induces lymphocyte proliferation, suggesting that activation of resting lymphocytes may have occurred. Although cytokine production was affected mainly by metal debris, cobalt toxicity may also modulate IL‐2 secretion, and even Co ion concentrations below the MHRA guideline levels (7 ppb) may contribute to the impairment of immune regulation in vivo in patients with MoM implants. Copyright © 2015 John Wiley & Sons, Ltd.
Investigating the neuroglial differentiation effect of neuroblastoma conditioned medium in human endometrial stem cells cultured on 3D nanofibrous scaffold
Authors: Ebrahimi‐Barough Somayeh , Hoveizi Elham , Norouzi Javidan Abbas , Ai Jafar 
Published: January 2015

AbstractNeural tissue engineering is an important area of research in the field of tissue‐engineering especially for neurodegenerative disease such as spinal cord injury. The differentiation capacity of human endometrial stem cells (hEnSCs) into neuronal cells has yet to be elucidated. Here, the major aim of the present study was to investigate the differentiation ability of hEnSCs cultured on polylactic acid/chitosan (PLA/CS) nanofibrous scaffold into neuroglial cells in response to conditioned medium of BE(2)‐C human neuroblastoma cells and growth factors. Here we investigated the use PLA/CS scaffold as a three dimensional (3D) system that increased neuro‐glial cells differentiation. Human EnSCs after three passages were differentiated in neuro‐glial like cells under neuroblastoma conditioned medium with FGF2/PDGF‐AA on PLA/CS scaffold. By day 18, differentiated cells were analyzed for expression of neuroglial markers by qRT‐PCR and immunofluorescence. The results revealed that hEnSCs attach, grow and differentiation on the nanofibrous PLA/CS scaffold. Additionally, our study showed the expression of neural and glial lineage markers such as Nestin, NF‐L, MAP2, PDGFRa, CNP, Olig2, MBP, and GFAP in the level of mRNA and MAP2, Tuj‐1, and NF‐L in the protein level after 18 days. Our results demonstrate that hEnSCs cultured on PLA/CS nanofibrous scaffold have the potential to differentiate in neuronal and glial cells in presence of neuroblastoma conditioned medium on PLA/CS scaffold. The result of this study may have impact in tissue engineering and cells‐base therapy of neurodegenerative diseases and have a great potential for wide application. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2621–2627, 2015.