bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and properties of octadecylamine modified graphene oxide/styrene‐butadiene rubber composites through an improved melt compounding method
Authors: Wang Chunwei , Liu Zijin , Wang Shifeng , Zhang Yong
Published: September 2015

Octadecylamine modified graphene oxide/styrene‐butadiene rubber (GO‐ODA/SBR) composites are prepared by a novel and environmental‐friendly method called “Improved melt compounding”. A GO‐ODA/ethanol paste mixture is prepared firstly, and then blended with SBR by melt compounding. GO‐ODA sheets are uniformly dispersed in SBR as confirmed by scanning electron microscope, transmission electron microscopy, and X‐ray diffraction. The interfacial interaction between GO‐ODA and SBR is weaker than that between GO and SBR, which is proved by equilibrium swelling test and dynamic mechanical analysis. GO‐ODA/SBR show more pronounced “Payne effect” than GO/SBR composites, indicating enhanced filler networks resulted from the modification of GO with ODA. GO‐ODA/SBR composite has higher tensile strength and elongation at break than SBR and GO/SBR composite. The tensile strength and elongation at break for the composite with 5 parts GO‐ODA per hundred parts of rubber increase by 208% and 172% versus neat SBR, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 42907.
Fabrication and characterization of double‐network agarose/polyacrylamide nanofibers by electrospinning
Authors: Cho Min Kyoung , Singu Bal Sydulu , Na Yang Ho , Yoon Kuk Ro
Published: September 2015

This study focused on the preparation of electrospun cross‐linked double‐network (DN) of agarose/polyacrylamide (PAAm) nanofibers. The agarose formed the first‐network that was physical‐linked by the agar helix bundles. After UV‐irradiation, the chemically crosslinked PAAm was formed as the second network. The resulting cross‐linked DN agarose/PAAm nanofibers were characterized by scanning electron microscopy (SEM), contact angle, attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FT‐IR), thermogravimetric analysis (TGA), and tensile test. SEM analysis shows the agarose/PAAM nanofibers present with the thickness of 187 nm. Agarose/PAAm nanofibers were showing FT‐IR spectral peaks at ∼1660, 1590, and 1070 cm−1 indicating the presence of both agarose and polyacrylamide in the crosslinked DN Agarose/PAAm nanofiber sheet, it suggests the strong interaction and good compatibility between the two components. Agarose/PAAm nanofiber sheet was showing thermal stability close to the pure polyacrylamide. From the tensile test study, agarose/PAAm strength improved by 66.66% compared to the pure agarose. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42914.
Reduction in cadmium‐induced toxicity by c‐Jun modulation in mouse embryo limb bud cells
Authors: Kapron Carolyn M. , Cheng Le
Published: September 2015

Background

While it is known that cadmium‐exposed embryonic cells have increased activation of c‐Jun N‐terminal kinase (JNK), the role of this stress signaling pathway in the embryotoxic response is not clear. Thus, the effects of modification of the transcription factor c‐Jun, one of the downstream targets of JNK, on cadmium‐induced embryotoxicity were investigated in primary cultures of mouse embryo limb bud cells.

Methods

Cultures of limb bud cells harvested on day 11 of gestation were pretreated with antisense oligonucleotides (ASO) to c‐Jun to reduce its expression, and then incubated with cadmium in the form of cadmium chloride. Toxicity was measured through assessments of cell proliferation and differentiation, while the effectiveness of the ASO in reducing c‐Jun was assessed through Western blotting using phosphorylation‐specific antibodies.

Results

When cells were treated with ASO c‐Jun, the total amounts of c‐Jun and also cadmium‐induced c‐Jun activation were diminished. Cadmium‐induced cytotoxicity, indicated by reduced cell numbers and differentiation, was found to decrease when cells were exposed to the antisense oligonucleotides to c‐Jun. In addition, limb cell numbers and differentiation were also enhanced by exposure to ASO in the absence of cadmium.

Conclusion

The JNK pathway, and particularly the downstream effector c‐Jun, appears to play an important role in regulating cell survival and differentiation in mouse embryo limb bud cells both in the presence and absence of the toxic metal cadmium. Birth Defects Research (Part A) 103:1039–1045, 2015. © 2015 Wiley Periodicals, Inc.
Epidemiology of venous thromboembolism (VTE) associated with pregnancy
Authors: Parunov Leonid A. , Soshitova Natalia P. , Ovanesov Mikhail V. , Panteleev Mikhail A. , Serebriyskiy Ilya I.
Published: September 2015

This review is focused on the epidemiology of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), associated with pregnancy. Superficial vein thrombosis, a less hazardous and less studied type of thrombosis in pregnant women, is beyond the scope of this review. This study discusses the VTE incidence rate in women from developed countries for both antepartum and postpartum periods and for subpopulations of women affected by additional risk factors, such as thrombophilias, circulatory diseases, preeclampsia of varying degrees of severity, and Caesarean section. To minimize bias due to historical changes in medical and obstetric practices, lifestyle, diet, etc., this review is generally limited to relatively recent studies, i.e., those that cover the last 35 years. The absolute risk or incidence rate was used to ascertain risk of VTE associated with pregnancy. For the studies where the direct incidence rates of VTE were not reported, we calculated an estimate of the observed but not reported absolute incidence rates using the data presented in respective articles. Birth Defects Research (Part C) 105:167–184, 2015. © 2015 Wiley Periodicals, Inc.
Persistent astrocyte activation in the fragile X mouse cerebellum
Authors: Pacey Laura K. K. , Guan Sihui , Tharmalingam Sujeenthar , Thomsen Christian , Hampson David R.
Published: September 2015

Background

Fragile X Syndrome, the most common single gene cause of autism, results from loss of the RNA‐binding protein FMRP. Although FMRP is highly expressed in neurons, it has also recently been identified in glia. It has been postulated that in the absence of FMRP, abnormal function of non‐neuronal cells may contribute to the pathogenesis of the disorder. We previously demonstrated reduced numbers of oligodendrocyte precursor cells and delayed myelination in the cerebellum of fragile X (Fmr1) knockout mice.

Methods

We used quantitative western blotting and immunocytochemistry to examine the status of astrocytes and microglia in the cerebellum of Fmr1 mice during development and in adulthood.

Results

We report increased expression of the astrocyte marker GFAP in the cerebellum of Fmr1 mice starting in the second postnatal week and persisting in to adulthood. At 2 weeks postnatal, expression of Tumor Necrosis Factor Receptor 2 (TNFR2) and Leukemia Inhibitory Factor (LIF) were elevated in the Fmr1 KO cerebellum. In adults, expression of TNFR2 and the glial marker S100β were also elevated in Fmr1 knockouts, but LIF expression was not different from wild‐type mice. We found no evidence of microglial activation or neuroinflammation at any age examined.

Conclusions

These findings demonstrate an atypical pattern of astrogliosis in the absence of microglial activation in Fmr1 knockout mouse cerebellum. Enhanced TNFR2 and LIF expression in young mice suggests that changes in the expression of astrocytic proteins may be an attempt to compensate for delayed myelination in the developing cerebellum of Fmr1 mice.
Identification and Characterization of the Streptazone E Biosynthetic Gene Cluster in Streptomyces sp. MSC090213JE08
Authors: Ohno Shoto , Katsuyama Yohei , Tajima Yuka , Izumikawa Miho , Takagi Motoki , Fujie Manabu , Satoh Noriyuki , Shin‐ya Kazuo , Ohnishi Yasuo
Published: September 2015

Streptazone derivatives isolated from Streptomyces species are piperidine alkaloids with a cyclopenta[b]pyridine scaffold. Previous studies indicated that these compounds are polyketides, but the biosynthetic enzymes responsible for their synthesis are unknown. Here, we have identified the streptazone E biosynthetic gene cluster in Streptomyces sp. MSC090213JE08, which encodes a modular type I PKS and tailoring enzymes that include an aminotransferase, three oxidoreductases, and two putative cyclases. The functions of the six tailoring enzymes were analyzed by gene disruption, and two putative biosynthetic intermediates that accumulated in particular mutants were structurally elucidated. On the basis of these results, we propose a pathway for the biosynthesis of streptazone E in which the two putative cyclases of the nuclear transport factor 2–like superfamily are responsible for C−C bond formation coupled with epoxide ring opening to give the five‐membered ring of streptazone E.
In Vitro Reconstitution of Formylglycine‐Generating Enzymes Requires Copper(I)
Authors: Knop Matthias , Engi Pascal , Lemnaru Roxana , Seebeck Florian P.
Published: September 2015

Formylglycine‐generating enzymes (FGEs) catalyze O2‐dependent conversion of specific cysteine residues of arylsulfatases and alkaline phosphatases into formylglycine. The ability also to introduce unique aldehyde functions into recombinant proteins makes FGEs a powerful tool for protein engineering. One limitation of this technology is poor in vitro activity of reconstituted FGEs. Although FGEs have been characterized as cofactor‐free enzymes we report that the addition of one equivalent of CuI increases catalytic efficiency more than 20‐fold and enables the identification of stereoselective C−H bond cleavage at the substrate as the rate‐limiting step. These findings remove previous limitations of FGE‐based protein engineering and also pose new questions about the catalytic mechanism of this O2‐utilizing enzyme.
Electrostatic Grafting of a Palladium N‐Heterocyclic Carbene Catalyst on a Periodic Mesoporous Organosilica and its Application in the Suzuki–Miyaura Reaction
Authors: Rajabi Fatemeh , Schaffner Dirk , Follmann Sascha , Wilhelm Christian , Ernst Stefan , Thiel Werner R.
Published: September 2015

A periodic mesoporous organosilica material functionalized with a Pd N‐heterocyclic carbene complex was synthesized by applying an electrostatic grafting method. The resulting hybrid material was characterized by solid‐state 29Si and 13C cross‐polarization magic‐angle spinning NMR spectroscopy, XRD, thermogravimetric analysis, and BET measurements. The hybrid was applied as a catalyst for the Suzuki–Miyaura cross‐coupling between aryl chlorides and phenylboronic acid under heterogeneous and aerobic conditions. The supported catalyst exhibited excellent activity and stability and it could be reused at least six times without any loss of activity. Atomic absorption spectroscopy detected no Pd contamination in the products, and leaching tests verified that the reaction was truly heterogeneous.
Iridicycle‐Catalysed Imine Reduction: An Experimental and Computational Study of the Mechanism
Authors: Chen Hsin‐Yi Tiffany , Wang Chao , Wu Xiaofeng , Jiang Xue , Catlow C. Richard A. , Xiao Jianliang
Published: September 2015

The mechanism of imine reduction by formic acid with a single‐site iridicycle catalyst has been investigated by density functional theory (DFT), NMR spectroscopy, and kinetic measurements. The NMR and kinetic studies suggest that the transfer hydrogenation is turnover‐limited by the hydride formation step. The calculations reveal that, amongst a number of possibilities, hydride formation from the iridicycle and formate probably proceeds by an ion‐pair mechanism, whereas the hydride transfer to the imino bond occurs in an outer‐sphere manner. In the gas phase, in the most favourable pathway, the activation energies in the hydride formation and transfer steps are 26–28 and 7–8 kcal mol−1, respectively. Introducing one explicit methanol molecule into the modelling alters the energy barrier significantly, reducing the energies to around 18 and 2 kcal mol−1 for the two steps, respectively. The DFT investigation further shows that methanol participates in the transition state of the turnover‐limiting hydride formation step by hydrogen‐bonding to the formate anion and thereby stabilising the ion pair.
Chelate‐Thiolate‐Coordinate Ligands Modulating the Configuration and Electrochemical Property of Dinitrosyliron Complexes (DNICs)
Authors: Yeh Shih‐Wey , Lin Chih‐Wei , Liu Bai‐Heng , Tsou Chih‐Chin , Tsai Ming‐Li , Liaw Wen‐Feng
Published: September 2015

As opposed to the reversible redox reaction ({Fe(NO)2}10 reduced‐form DNIC [(NO)2Fe(S(CH2)3S)]2− (1)⇌{Fe(NO)2}9 oxidized‐form [(NO)2Fe(S(CH2)3S)]−), the chemical oxidation of the {Fe(NO)2}10 DNIC [(NO)2Fe(S(CH2)2S)]2− (2) generates the dinuclear {Fe(NO)2}9–{Fe(NO)2}9 complex [(NO)2Fe(μ‐SC2H4S)2Fe(NO)2]2− (3) bridged by two terminal [SC2H4S]2− ligands. On the basis of the Fe K‐edge pre‐edge energy and S K‐edge XAS, the oxidation of complex 1 yielding [(NO)2Fe(S(CH2)3S)]− is predominantly a metal‐based oxidation. The smaller S1‐Fe1‐S2 bond angle of 94.1(1)° observed in complex 1 (S1‐Fe1‐S2 88.6(1)° in complex 2), compared to the bigger bond angle of 100.9(1)° in the {Fe(NO)2}9 DNIC [(NO)2Fe(S(CH2)3S)]−, may be ascribed to the electron‐rich {Fe(NO)2}10 DNIC preferring a restricted bite angle to alleviate the electronic donation of the chelating thiolate to the electron‐rich {Fe(NO)2}10 core. The extended transition state and natural orbitals for chemical valence (ETS‐NOCV) analysis on the edt‐/pdt‐chelated {Fe(NO)2}9 and {Fe(NO)2}10 DNICs demonstrates how two key bonding interactions, that is, a FeS covalent σ bond and thiolate to the Fe d charge donation, between the chelating thiolate ligand and the {Fe(NO)2}9/10 core could be modulated by the backbone lengths of the chelating thiolate ligands to tune the electrochemical redox potential (E1/2=−1.64 V for complex 1 and E1/2=−1.33 V for complex 2) and to dictate structural rearrangement/chemical transformations (S‐Fe‐S bite angle and monomeric vs. dimeric DNICs).
Catalytic Transfer Hydrogenation with a Methandiide‐Based Carbene Complex: An Experimental and Computational Study
Authors: Weismann Julia , Gessner Viktoria H.
Published: September 2015

The transfer hydrogenation (TH) reaction of ketones with catalytic systems based on a methandiide‐derived ruthenium carbene complex was investigated and optimised. The complex itself makes use of the noninnocent behaviour of the carbene ligand (MCR2→MHC(H)R2), but showed only moderate activity, thus requiring long reaction times to achieve sufficient conversion. DFT studies on the reaction mechanism revealed high reaction barriers for both the dehydrogenation of iPrOH and the hydrogen transfer. A considerable improvement of the catalytic activity could be achieved by employing triphenylphosphine as additive. Mechanistic studies on the role of PPh3 in the catalytic cycle revealed the formation of a cyclometalated complex upon phosphine coordination. This ruthenacycle was revealed to be the active species under the reaction conditions. The use of the isolated complex resulted in high catalytic activities in the TH of aromatic as well as aliphatic ketones. The complex was also found to be active under base‐free conditions, suggesting that the cyclometalation is crucial for the enhanced activity.
Functionality, Effectiveness, and Mechanistic Evaluation of a Multicatalyst‐Promoted Reaction Sequence by Electrospray Ionization Mass Spectrometry
Authors: Alachraf M. Wasim , Wende Raffael C. , Schuler Sören M. M. , Schreiner Peter R. , Schrader Wolfgang
Published: September 2015

A multicatalytic three‐step reaction consisting of epoxidation, hydrolysis, and enantioselective monoacylation of cyclohexene was studied by using mass spectrometry (MS). The reaction sequence was carried out in a one‐pot reaction using a multicatalyst. All reaction steps were thoroughly analyzed by electrospray ionization (ESI) MS (and MS/MS), as well as high‐resolution MS for structure elucidation. These studies allow us to shed light on the individual mode of action of each catalytic moiety. Thus, we find that under the epoxidation conditions, the catalytically active N‐methyl imidazole for the terminal acylation step is partially deactivated through oxidation. This observation helps to explain the lower efficiency of the catalyst in the last step compared to the monoacylation performed separately. All reactive intermediates and products of the reaction sequence, as well as of the side‐reactions, were monitored, and we present a working mechanism of the reaction.
Hetero‐Selective DNA‐Like Duplex Stabilized by Donor–Acceptor Interactions
Authors: Doi Tetsuya , Sakakibara Takumi , Kashida Hiromu , Araki Yasuyuki , Wada Takehiko , Asanuma Hiroyuki
Published: September 2015

We report on the characterization of a novel hetero‐selective DNA‐like duplex of pyrene and anthraquinone pseudo base pairs. The pyrene/anthraquinone pairs showed excellent selectivity in hetero‐recognition and even trimers were found to form a hetero‐duplex. Pyrene and anthraquinone moieties were tethered on acyclic D‐threoninol linkers and linked to adjacent residues by using standard phosphoramidite chemistry. When pyrene and anthraquinone were incorporated at pairing positions in complementary strands of natural DNA oligonucleotides, the duplex was stabilized significantly. Moreover, a pyrene hexamer and an anthraquinone hexamer formed a stable artificial hetero‐duplex without the assistance of natural base pairs. The pyrene/anthraquinone pair was so stable that even trimers formed a hetero‐duplex under conditions in which natural DNA strands of three residues do not.
Lewis Acid Coupled Electron Transfer of Metal–Oxygen Intermediates
Authors: Fukuzumi Shunichi , Ohkubo Kei , Lee Yong‐Min , Nam Wonwoo
Published: September 2015

Redox‐inactive metal ions and Brønsted acids that function as Lewis acids play pivotal roles in modulating the redox reactivity of metal–oxygen intermediates, such as metal–oxo and metal–peroxo complexes. The mechanisms of the oxidative CH bond cleavage of toluene derivatives, sulfoxidation of thioanisole derivatives, and epoxidation of styrene derivatives by mononuclear nonheme iron(IV)–oxo complexes in the presence of triflic acid (HOTf) and Sc(OTf)3 have been unified as rate‐determining electron transfer coupled with binding of Lewis acids (HOTf and Sc(OTf)3) by iron(III)–oxo complexes. All logarithms of the observed second‐order rate constants of Lewis acid‐promoted oxidative CH bond cleavage, sulfoxidation, and epoxidation reactions of iron(IV)–oxo complexes exhibit remarkably unified correlations with the driving forces of proton‐coupled electron transfer (PCET) and metal ion‐coupled electron transfer (MCET) in light of the Marcus theory of electron transfer when the differences in the formation constants of precursor complexes were taken into account. The binding of HOTf and Sc(OTf)3 to the metal–oxo moiety has been confirmed for MnIV–oxo complexes. The enhancement of the electron‐transfer reactivity of metal–oxo complexes by binding of Lewis acids increases with increasing the Lewis acidity of redox‐inactive metal ions. Metal ions can also bind to mononuclear nonheme iron(III)–peroxo complexes, resulting in acceleration of the electron‐transfer reduction but deceleration of the electron‐transfer oxidation. Such a control on the reactivity of metal–oxygen intermediates by binding of Lewis acids provides valuable insight into the role of Ca2+ in the oxidation of water to dioxygen by the oxygen‐evolving complex in photosystem II.
Three‐Dimensional Nitrogen‐Doped Reduced Graphene Oxide–Carbon Nanotubes Architecture Supporting Ultrafine Palladium Nanoparticles for Highly Efficient Methanol Electrooxidation
Authors: Song Hejie , Yang Liming , Tang Yanhong , Yan Dafeng , Liu Chengbin , Luo Shenglian
Published: September 2015

A three‐dimensional (3D) nitrogen‐doped reduced graphene oxide (rGO)–carbon nanotubes (CNTs) architecture supporting ultrafine Pd nanoparticles is prepared and used as a highly efficient electrocatalyst. Graphene oxide (GO) is first used as a surfactant to disperse pristine CNTs for electrochemical preparation of 3D rGO@CNTs, and subsequently one‐step electrodeposition of the stable colloidal GO–CNTs solution containing Na2PdCl4 affords rGO@CNTs‐supported Pd nanoparticles. Further thermal treatment of the Pd/rGO@CNTs hybrid with ammonia achieves not only in situ nitrogen‐doping of the rGO@CNTs support but also extraordinary size decrease of the Pd nanoparticles to below 2.0 nm. The resulting catalyst is characterized by scanning and transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, and X‐ray photoelectron spectroscopy. Catalyst performance for the methanol oxidation reaction is tested through cyclic voltammetry and chronoamperometry techniques, which shows exceedingly high mass activity and superior durability.
Sustainable Synthesis of Chiral Tetrahydrofurans through the Selective Dehydration of Pentoses
Authors: Foster Robert W. , Tame Christopher J. , Bučar Dejan‐Krešimir , Hailes Helen C. , Sheppard Tom D.
Published: September 2015

L‐Arabinose is an abundant resource available as a waste product of the sugar beet industry. Through use of a hydrazone‐based strategy, L‐arabinose was selectively dehydrated to form a chiral tetrahydrofuran on a multi‐gram scale without the need for protecting groups. This approach was extended to other biomass‐derived reducing sugars and the mechanism of the key cyclization investigated. This methodology was applied to the synthesis of a range of functionalized chiral tetrahydrofurans, as well as a formal synthesis of 3R‐3‐hydroxymuscarine.
Increased Microbial Butanol Tolerance by Exogenous Membrane Insertion Molecules
Authors: Hinks Jamie , Wang Yaofeng , Matysik Artur , Kraut Rachel , Kjelleberg Staffan , Mu Yuguang , Bazan Guillermo C. , Wuertz Stefan , Seviour Thomas
Published: September 2015

Butanol is an ideal biofuel, although poor titers lead to high recovery costs by distillation. Fluidization of microbial membranes by butanol is one of the major factors limiting titers in butanol‐producing bioprocesses. Starting with the hypothesis that certain membrane insertion molecules would stabilize the lipid bilayer in the presence of butanol, we applied a combination of in vivo and in vitro techniques within an in silico framework to describe a new approach to achieve solvent tolerance in bacteria. Single‐molecule tracking of a model supported bilayer showed that COE1‐5C, a five‐ringed oligo‐polyphenylenevinylene conjugated oligoelectrolyte (COE), reduced the diffusion rate of phospholipids in a microbially derived lipid bilayer to a greater extent than three‐ringed and four‐ringed COEs. Furthermore, COE1‐5C treatment increased the specific growth rate of E. coli K12 relative to a control at inhibitory butanol concentrations. Consequently, to confer butanol tolerance to microbes by exogenous means is complementary to genetic modification of strains in industrial bioprocesses, extends the physiological range of microbes to match favorable bioprocess conditions, and is amenable with complex and undefined microbial consortia for biobutanol production. Molecular dynamics simulations indicated that the π‐conjugated aromatic backbone of COE1‐5C likely acts as a hydrophobic tether for glycerophospholipid acyl chains by enhancing bilayer integrity in the presence of high butanol concentrations, which thereby counters membrane fluidization. COE1‐5C‐mitigated E. coli K12 membrane depolarization by butanol is consistent with the hypothesis that improved growth rates in the presence of butanol are a consequence of improved bilayer stability.
Deterministic K‐means secure coverage clustering with periodic authentication for wireless sensor networks
Authors: Bala Krishna M. , Doja M. N.
Published: September 2015

Innovative and emerging developments in sensor networks are proven to be the backbone for real‐time applications such as satellite communications, military and border area surveillance systems, health care systems, traffic monitoring systems, seismic and underwater monitoring systems, and agriculture and habitat environment systems. Coverage and clustering techniques enable the sensor network to operate in group‐based and region‐based communication and thus save the node energy. Energy‐efficient protocols save the node energy and increase the network life cycle in a resource‐constrained sensor network. Cluster head (CH) node manages and controls the operations such as network topology, coverage area, and routing paths (multi‐paths and fault‐tolerant paths) of the network. In this paper, we present deterministic K‐means secure coverage clustering (K‐SCC) with periodic authentication. The proposed protocol uses coverage clustering technique with periodic authentication between the CH node and sensor nodes to establish the secure channel in the network. Maximum cover of K nodes is maintained in the secure coverage cluster to achieve authenticated communication between the sensor nodes in the network. The proposed K‐SCC protocol is compared with the existing protocols such as deterministic‐SCC and random‐SCC protocols. Simulation results indicate that the proposed K‐SCC protocol achieves an average of 84% coverage ratio (cluster/sensor node ratio) as compared with 62% coverage ratio in the existing SCC protocols. Simulations also indicate that the proposed K‐SCC protocol consumes 20% less energy as compared with the existing SCC protocol. Copyright © 2015 John Wiley & Sons, Ltd.
Oxidative stress, type 2 diabetes and vitamin D: past, present and future
Authors: Nikooyeh Bahareh , Neyestani Tirang R.
Published: September 2015

Oxidative stress refers to an imbalance between potentially harmful free radicals and the body's mechanisms to efficiently detoxify them in favor of the free radicals. Consequently, excess free radicals can attack and damage a wide range of biomolecules including proteins, lipids and nucleic acids. Antioxidant mechanisms of the body are under the influence of genetic and environmental (including dietary) factors. Diabetes is one of the most common metabolic disorders around the world. A huge body of evidence indicates a role for oxidative stress in development of many human diseases including diabetes. In this article, the latest information on the possible links of oxidative stress with diabetes development, control and complications as well as the newest results of antioxidant supplementation trials is reviewed. In addition, the possible role of vitamin D, as a newly recognized antioxidant in diabetes is discussed. Finally, concluding remarks on pivotal issues and future studies are presented. Copyright © 2015 John Wiley & Sons, Ltd.
Association of parental history of type 2 diabetes with age, lifestyle, anthropometric factors, and clinical severity at type 2 diabetes diagnosis: results from the DD2 study
Authors: Svensson Elisabeth , Berencsi Klara , Sander Simone , Mor Anil , Rungby Jørgen , Nielsen Jens Steen , Friborg Søren , Brandslund Ivan , Christiansen Jens Sandahl , Vaag Allan , Beck‐Nielsen Henning , Sørensen Henrik Toft , Thomsen Reimar Wernich
Published: September 2015

Background

We investigated whether parental history of type 2 diabetes mellitus (T2D) is associated with age, lifestyle, anthropometric factors, and clinical severity at the time of T2D diagnosis.

Methods

We conducted a cross‐sectional study based on the Danish Centre for Strategic Research in Type 2 Diabetes cohort. We examined the prevalence ratios (PR) of demographic, lifestyle, anthropometric, and clinical factors according to parental history, using Poisson regression adjusting for age and gender.

Results

Of 2825 T2D patients, 34% (n = 964) had a parental history of T2D. Parental history was associated with younger age at diagnosis [adjusted (a)PR 1.66, 95% confidence interval: 1.19, 2.31) for age <40 years; aPR 1.36 (95% confidence interval: 1.24, 1.48) for ages 40–59 years] and with higher baseline fasting plasma glucose [≥7.5 mmol/L, aPR 1.47 (95% confidence interval: 1.20, 1.80)], and also tended to be associated with lower beta cell function. In contrast, patients both with and without a parental history had similar occurrence of central obesity [91% vs. 91%], weight gain ≥30 kg since age 20 [52% vs. 53%], and lack of regular physical activity [60% vs. 58%]. Presence of diabetes complications or comorbidities at T2D diagnosis was not associated with parental history.

Conclusions

The lack of an association between parental history and adverse lifestyle factors indicates that T2D patients do not inherit a particular propensity for overeating or inactivity, whereas patients with a parental history may have more severe pancreatic beta cell dysfunction at diagnosis. Copyright © 2015 John Wiley & Sons, Ltd.
An experimental investigation of the consequences and social functions of fat talk in friendship groups
Authors: Cruwys Tegan , Leverington Carly T. , Sheldon Anne M.
Published: September 2015

Objective

Fat talk is a form of self‐degrading, thin‐ideal endorsing communication that occurs within female friendship groups. Previous studies have suggested negative associations with wellbeing, but have been predominantly correlational and based on self‐report. This study aimed to assess the causal relationship between fat talk and the correlates of disordered eating (thin‐ideal internalization, body dissatisfaction, negative affect, and dieting intentions) by experimentally manipulating fat talk in existing friendship groups and measuring naturalistic expression of fat talk and its effects.

Methods

Participants were 85 women aged 17–25 who completed the experiment in friendship pairs. They were randomly assigned to a condition in which their friend expressed fat talk, positive body talk, or neutral talk.

Results

This study found evidence of a causal link between listening to friends fat talk and increased correlates of disordered eating. The negative effects of listening to fat talk were fully mediated by fat talk expression. This study also revealed a social function of fat talk, whereby participants rated their friends more positively when they were perceived to behave consistently with group norms, either pro‐ or anti‐fat talk. Positive body talk showed none of the negative effects of fat talk, and was considered socially acceptable regardless of existing friendship group norms.

Discussion

These findings indicate that fat talk is a mechanism through which the thin ideal is transmitted between individuals. Interventions at the level of the friendship group to challenge norms and communication styles may break the link between societal risk factors and individual risk of eating disorders. © 2015 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:84–91).
Interleukin‐2 critically regulates bone marrow erythropoiesis and prevents anemia development
Authors: Chopra Martin , Langenhorst Daniela , Beilhack Andreas , Serfling Edgar , Patra Amiya K.
Published: September 2015

Mice deficient in IL‐2 signaling develop severe anemia indicating a defect in erythropoiesis. However, why deficiency in IL‐2, an essential growth factor for lymphocytes, or in IL‐2 signaling components should result in defective erythropoiesis is unclear. Here, we have analyzed the mechanism of IL‐2 signaling deficiency induced anemia in mice and show that IL‐2 plays an indispensable role in bone marrow (BM) erythropoiesis via maintenance of regulatory T (Treg) cells. In absence of IL‐2 signaling, IFN‐γ produced by the activated T cells suppressed klf1 expression, resulting in an early block in erythrocyte differentiation. Anemia, in IL‐2 or IL‐2 signaling deficient mice always developed prior to the manifestation of other autoimmune complications such as colitis, suggesting that anemia in these mice might be a contributing factor in inducing other pathological complications in later stages. Our study shows, how essential cytokines of lymphoid cells could exert critical influence on the development of erythrocytes and thus expanding our understanding of the complex regulation of hematopoiesis in the BM. Besides, our findings might facilitate the use of IL‐2 and anti‐IFN‐γ as a clinical remedy against anemia that arise in cancer patients following radiotherapy or chemotherapy, a context which simulates the situation of IL‐2 deficiency.
Nanobioinorganic Chemistry: Converging Inorganic Chemistry and Biology at the Nanoscale
Authors: Trindade Tito , Wong Wing‐Tak
Published: September 2015

It has become clear in recent years that the interaction of inorganic nanomaterials with biological systems is of paramount importance for further advancements in important fields, including nanomedicine, nanotoxicology, tissue engineering, biotechnology, environmental science, and bioimaging, among many others. This development reflects not merely new applications of nanoparticles to biological systems but also the emergence of new biotechnologies involving inorganic nanomaterials.
Facile Synthesis of Nitrogen‐Doped Porous Carbon‐Gold Hybrid Nanocomposite for Mercury(II) Ion Electrochemical Determination
Authors: Guan Qing , Xiong Wei , Zhou Lan , Liu Shantang
Published: September 2015

A facile method was developed for the synthesis of nitrogen‐doped porous carbon‐gold (NPCAu) hybrid nanocomposite. The NPCAu modified gold electrode has been prepared for the electrochemical determination of ultratrace mercury(II) in drinking water through square wave anodic stripping voltammetry (SWASV). Under optimized conditions, the NPCAu modified electrode shows a sensitive detection to Hg(II) ion present in concentrations of 0.001∼1 μM, with a detection limit of 0.35 nM (S/N=3), which was much lower than the guideline values in drinking water given by the World Health Organization.
Forensic performance of Investigator DIPplex indels genotyping kit in native, immigrant, and admixed populations in South Africa
Authors: Hefke Gwynneth , Davison Sean , D'Amato Maria Eugenia
Published: September 2015

The utilization of binary markers in human individual identification is gaining ground in forensic genetics. We analyzed the polymorphisms from the first commercial indel kit Investigator DIPplex (Qiagen) in 512 individuals from Afrikaner, Indian, admixed Cape Colored, and the native Bantu Xhosa and Zulu origin in South Africa and evaluated forensic and population genetics parameters for their forensic application in South Africa.

The levels of genetic diversity in population and forensic parameters in South Africa are similar to other published data, with lower diversity values for the native Bantu. Departures from Hardy–Weinberg expectations were observed in HLD97 in Indians, Admixed and Bantus, along with 6.83% null homozygotes in the Bantu populations. Sequencing of the flanking regions showed a previously reported transition G>A in rs17245568.

Strong population structure was detected with Fst, AMOVA, and the Bayesian unsupervised clustering method in STRUCTURE. Therefore we evaluated the efficiency of individual assignments to population groups using the ancestral membership proportions from STRUCTURE and the Bayesian classification algorithm in Snipper App Suite. Both methods showed low cross‐assignment error (0–4%) between Bantus and either Afrikaners or Indians. The differentiation between populations seems to be driven by four loci under positive selection pressure. Based on these results, we draw recommendations for the application of this kit in SA.
Comparison of integrated genotoxicity endpoints in rats after acute and subchronic oral doses of 4‐nitroquinoline‐1‐oxide
Authors: Roberts Daniel J. , McKeon Marie , Xu Yong , Stankowski Leon F.
Published: September 2015

During interlaboratory validation trials for the Pig‐a gene mutation assay we assessed the genotoxicity of 4‐nitroquinoline‐1‐oxide (4NQO) across endpoints in multiple tissues: induction of Pig‐a mutant red blood cells (RBCs) and reticulocytes (RETs); micronucleated RETs (MN RETs); and DNA damage in blood and liver via the alkaline Comet assay (%tail intensity [TI]). In a previous subchronic toxicity study with 28 daily doses, biologically meaningful increases were observed only for Pig‐a mutant RBCs/RETs while marginal increases in the frequency of MN RET were observed, and other clastogenic endpoints were negative. Follow up acute studies were performed using the same cumulative doses (0, 35, 70, 105, and 140 mg/kg) administered in a bolus, or split over three equal daily doses, with samples collected up to 1 month after the last dose. Both of the acute dosing regimens produced similar results, in that endpoints were either positive or negative, regardless of 1 or 3 daily doses, but the three consecutive daily dose regimen yielded more potent responses in TI (in liver and blood) and Pig‐a mutant frequencies. In these acute studies the same cumulative doses of 4NQO induced positive responses in clastogenic endpoints that were negative or inconclusive using a subchronic study design. Additionally, a positive control group using combination doses of cyclophosphamide and ethyl methanesulfonate was employed to assess assay validity and potentially identify a future positive control treatment for integrated genetic toxicity studies. Environ. Mol. Mutagen. 57:17–27, 2016. © 2015 Wiley Periodicals, Inc.
Mixed lineage kinase 3 mediates release of C‐X‐C motif ligand 10–bearing chemotactic extracellular vesicles from lipotoxic hepatocytes
Authors: Ibrahim Samar H. , Hirsova Petra , Tomita Kyoko , Bronk Steven F. , Werneburg Nathan W. , Harrison Stephen A. , Goodfellow Val S. , Malhi Harmeet , Gores Gregory J.
Published: September 2015

Mixed lineage kinase 3 (MLK3) deficiency reduces macrophage‐associated inflammation in a murine model of nonalcoholic steatohepatitis (NASH). However, the mechanistic links between MLK3 activation in hepatocytes and macrophage‐driven inflammation in NASH are uncharted. Herein, we report that MLK3 mediates the release of (C‐X‐C motif) ligand 10 (CXCL10)‐laden extracellular vesicles (EVs) from lipotoxic hepatocytes, which induce macrophage chemotaxis. Primary mouse hepatocytes (PMHs) and Huh7 cells were treated with palmitate or lysophosphatidylcholine (LPC). Released EVs were isolated by differential ultracentrifugation. LPC treatment of PMH or Huh7 cells induced release of EVs, which was prevented by either genetic or pharmacological inhibition of MLK3. Mass spectrometry identified the potent chemokine, CXCL10, in the EVs, which was markedly enriched in EVs isolated from LPC‐treated hepatocytes versus untreated cells. Green fluorescent protein (GFP)‐tagged CXCL10 was present in vesicular structures and colocalized with the red fluorescent protein (RFP)‐tagged EV marker, CD63, after LPC treatment of cotransfected Huh‐7 cells. Either genetic deletion or pharmacological inhibition of MLK3 prevented CXCL10 enrichment in EVs. Treatment of mouse bone‐marrow–derived macrophages with lipotoxic hepatocyte‐derived EVs induced macrophage chemotaxis, an effect blocked by incubation with CXCL10‐neutralizing antisera. MLK3‐deficient mice fed a NASH‐inducing diet had reduced concentrations of total plasma EVs and CXCL10 containing EVs compared to wild‐type mice. Conclusions: During hepatocyte lipotoxicity, activated MLK3 induces the release of CXCL10‐bearing vesicles from hepatocytes, which are chemotactic for macrophages. (Hepatology 2016;63:731–744)
Resolving the Manganese Oxidation States in the Oxygen‐evolving Catalyst of Natural Photosynthesis
Authors: Krewald Vera , Neese Frank , Pantazis Dimitrios A.
Published: September 2015

A frequent challenge when dealing with multinuclear transition metal clusters in biology is to determine the absolute oxidation states of the individual metal ions and to identify how they evolve during catalytic turnover. The oxygen‐evolving complex of biological photosynthesis, an active site that harbors an oxo‐bridged Mn4Ca cluster as the water‐oxidizing species, offers a prime example of such a challenge that withstood satisfactory resolution for decades. A multitude of experimental studies have approached this question and have offered insights from different angles, but they were also accompanied by incomplete or inconclusive interpretations. Only very recently, through a combination of experiment and theory, has a definitive assignment of the individual Mn oxidation states been achieved for all observable catalytic states of the complex. Here we review the information obtained by structural and spectroscopic methods, describe the interpretation and synthesis achieved through quantum chemistry, and summarize our current understanding of the electronic structure of nature’s water splitting catalyst.
Natural Quorum Sensing Inhibitors – Small Molecules, Big Messages
Authors: Delago Antonia , Mandabi Aviad , Meijler Michael M.
Published: September 2015

Due to the increasing emergence of antibiotic resistant bacterial strains within the past few decades, bacterial infections in general – and hospital‐borne infections, in particular – have become increasingly difficult to fight. It is therefore crucial to find new strategies to fight pathogenic bacteria. Targeted inhibition of quorum sensing (QS) presents a promising alternative. QS is a cell density‐dependent signaling pathway used for intra‐ and interspecies coordination of gene expression. In many bacteria, pathogenic phenotypes, as well as the expression of virulence factors, are under the control of QS regulons. A closer look at natural quorum sensing inhibitors may be helpful to identify potent compounds that can be used as alternatives to antibiotics. Moreover, it will also provide insight into the interactions between species that compete for the same habitat and resources. This review aims to summarize our current knowledge concerning natural QS inhibitors, as a starting point for the design and synthesis of new therapeutics to treat or prevent bacterial infections.
Spatial coherence of extreme precipitation events in the Northwestern United States
Authors: Parker Lauren E. , Abatzoglou John T.
Published: September 2015

The complexity of impacts resulting from extreme precipitation events varies with the spatial extent of precipitation extremes. Characteristics of precipitation extremes, defined by the top 5% of 3‐day accumulated precipitation, including their spatial coherence and relationships to two contrasting synoptic phenomena, were examined at stations across the Northwestern United States. The spatial coherence of precipitation extremes generally decayed with distance between stations. However, distinct geographic variability in region‐wide coherence of precipitation extremes was present with overall higher coherence west of the Cascades, and lower coherence in the lee of the Cascades and Northern Rocky Mountains. Illustrative patterns of coherence were also seen with respect to atmospheric circulation regimes; atmospheric rivers favoured broadly coherent extremes occurring primarily west of the Cascades during fall and winter, while closed lows favoured more isolated precipitation extremes in the lee of the Northern Rocky Mountains and Cascades, occurring primarily during spring. Geographic variability in spatial coherence, direction of maximum coherence and seasonality of extremes suggest that extreme precipitation events result from the interaction of atmospheric circulation and complex topography.
Arabian Sea SST evolution during spring to summer transition period and the associated processes in coupled climate models
Authors: Sayantani Ojha , Gnanaseelan Chellappan , Chowdary Jasti S. , Parekh Anant , Rahul Sivan
Published: September 2015

Many climate models have problems in simulating the sea surface temperature (SST) in the tropical Indian Ocean (TIO). The Coupled Model Inter‐comparison Project Phase 5 (CMIP5) models, in general, underestimate SST over the entire TIO region. This study examines the SST evolution during spring to summer transition months (May and June) over the Arabian Sea (AS) region in the historical simulations of 13 CMIP5 models and the Climate Forecasting System coupled models CFSv1 and CFSv2. The annual cycle of SST shows that the summer monsoon cooling is not adequately captured by many models. Based on the state of June SST tendency, models have been divided in to three groups, the first group (G1) consists of models having stronger than observed cooling, second group (G2) considers models having closer to observed cooling and the third group (G3) includes models having lesser than observed cooling. Mixed layer heat budget analysis revealed that atmospheric flux is mainly responsible for unrealistic SST warming in most of the G3 models during June. The vertical mixing and horizontal advection contribute considerably to the SST cooling in summer (June) especially for G1 and G2 models. On the other hand, spring warming in all the models is consistently forced by the surface heat flux. It is also found that the monsoon low‐level jet (LLJ) is not accurately represented in most of the models. The misrepresentation of LLJ causes bias in the oceanic processes leading to unrealistic SST evolution in many models. One way of LLJ affecting the oceanic processes is by modulating mixed layer depth (MLD). It is observed in general that the models with deeper MLD display strong SST cooling. The model deficiency in representing AS SST is speculated to be a major limiting factor in capturing the monsoon rainfall in the current coupled models. The proper simulation of AS SST is therefore very crucial for the accurate representation of Indian summer monsoon precipitation.
Multiple injections of leukoreduced platelet rich plasma reduce pain and functional impairment in a canine model of ACL and meniscal deficiency
Authors: Cook James L. , Smith Patrick A. , Bozynski Chantelle C. , Kuroki Keiichi , Cook Cristi R. , Stoker Aaron M. , Pfeiffer Ferris M.
Published: September 2015

Platelet rich plasma (PRP) is used to treat many musculoskeletal disorders. We used a canine model to determine the effects of multiple intra‐articular injections of leukoreduced PRP (ACP) on anterior cruciate ligament healing, meniscal healing, and progression of osteoarthritis (OA). With Animal Care and Use Committee (ACUC) approval, 12 dogs underwent partial ACL transection and meniscal release in one knee. At weeks 1, 2, 3, 6, and 8 after insult, dogs were treated with intra‐articular injections (2 ml) of either ACP (n = 6) or saline (n = 6). Dogs were assessed over 6 months to determine comfortable range of motion (CROM), lameness, pain, effusion, kinetics, and radiographic and arthroscopic assessments. At 6‐month endpoint, dogs were assessed for ACL material properties and histopathology. Saline‐treated dogs had significantly (p < 0.04) more CROM loss, significantly (p < 0.01) more pain, significantly (p < 0.05) more severe lameness, significantly (p < 0.05) lower function, and significantly (p < 0.05) lower %Total Pressure Index in affected hindlimbs compared to ACP‐treated dogs. Radiographic OA increased significantly (p < 0.01) over time within each group. Arthroscopically, saline‐treated knees showed moderate to severe synovitis, further ACL disruption, and medial compartment cartilage loss, and ACP‐treated knees showed evidence of ACL repair and less severe synovitis. ACL material properties in ACP‐treated knees were closer to normal than in saline‐treated knees, however, the differences were not statistically significant. ACL histopathology was significantly (p< 0.05) less severe in ACP‐treated knees compared to saline‐treated knees. Five intra‐articular injections of leukoreduced PRP had beneficial effects for ACL healing, improved range of motion, decreased pain, and improved limb function for up to 6 months in this model. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:607–615, 2016.