bluuebunny/crossref_metadata_2025 huggingface dataset:
Counterion‐Induced Asymmetric Control in Ring‐Opening of Azetidiniums: Facile Access to Chiral Amines
Authors: Qian Deyun , Chen Min , Bissember Alex C. , Sun Jianwei
Published: February 2018

Counterion‐induced stereocontrol is a powerful tool in organic synthesis. However, such enantiocontrol on tetrahedral ammonium cations remains challenging. Described here is the first example of using chiral anion phase‐transfer catalysis to achieve intermolecular ring‐opening of azetidiniums with excellent enantioselectivity (up to 97 % ee). Precise control over the formation and reaction of the chiral ion pair as well as inhibition of the background reaction by the biphasic system is key to the success of the reaction.
Reversible Phase Transfer of Carbon Dots between an Organic Phase and Aqueous Solution Triggered by CO2
Authors: Pei Xiaoyan , Xiong Dazhen , Wang Huiyong , Gao Shuaiqi , Zhang Xinying , Zhang Suojiang , Wang Jianji
Published: February 2018

Carbon dots (CDs) have attracted increasing attention in applications such as bio‐imaging, sensors, catalysis, and drug delivery. However, unlike metallic and semiconductor nanoparticles, the transfer of CDs between polar and non‐polar phases is little understood. A class of amine‐terminated CDs is developed and their phase transfer behavior has been investigated. It is found that these CDs can reversibly transfer between aqueous and organic solvents by alternatively bubbling and removing CO2 at atmospheric pressure. The mechanism of such CO2‐switched phase transfer involves reversible acid–base reaction of amine‐terminated CDs with CO2 and the reversible formation of hydrophilic ammonium salts. By using the CDs as catalysts, the phase transfer is applied in the Knoevenagel reaction for efficient homogeneous reaction, heterogeneous separation, and recycling of the catalysts.
Blending Non‐Group‐3 Transition Metal and Rare‐Earth Metal into a C80 Fullerene Cage with D5h Symmetry
Authors: Wei Tao , Jin Fei , Guan Runnan , Huang Jing , Chen Muqing , Li Qunxiang , Yang Shangfeng
Published: February 2018

Rare‐earth metals have been mostly entrapped into fullerene cages to form endohedral clusterfullerenes, whereas non‐Group‐3 transition metals that can form clusterfullerenes are limited to titanium (Ti) and vanadium (V), and both are exclusively entrapped within an Ih‐C80 cage. Non‐Group‐3 transition‐metal‐containing endohedral fullerenes based on a C80 cage with D5h symmetry, VxSc3−xN@D5h‐C80 (x=1, 2), have now been synthesized, which exhibit two variable cluster compositions. The molecular structure of VSc2N@D5h‐C80 was unambiguously determined by X‐ray crystallography. According to a comparative study with the reported Ti‐ and V‐containing clusterfullerenes based on a Ih‐C80 cage and the analogous D5h‐C80‐based metal nitride clusterfullerenes containing rare‐earth metals only, the decisive role of the non‐Group‐3 transition metal on the formation of the corresponding D5h‐C80‐based clusterfullerenes is unraveled.
Effective gas separation through graphene oxide containing mixed matrix membranes
Authors: Feijani Elahe Ahmadi , Tavassoli Ahmad , Mahdavi Hossein , Molavi Hossein
Published: February 2018

In the present study, graphene oxide (GO) was incorporated into poly(vinylidene fluoride) (PVDF) and chemically modified PVDF (M‐PVDF) to prepare mixed matrix membranes (MMMs) for gas separation application. Performed analyses proved appropriate dispersion of exfoliated GO sheets in polymer matrices and sufficient compatibility at the interfacial phases. M‐PVDF based MMMs were thermally and mechanically more stable relative to the PVDF‐based MMMs. The oxygen containing functional groups in M‐PVDF was probably the main reason for this more stability. PVDF/GO MMMs rendered low gas permeability and high selectivity. Both impermeable GO sheets and crystalline phases of PVDF were responsible for such behavior. On the other hand, interestingly gas permeability of M‐PVDF/GO MMMs was enhanced while no substantial decline was recorded in gas selectivity. For instance, He and CO2 permeability was increased 12.46% and 25.89%, respectively, compared to the pure PVDF membrane. This behavior originated from functional groups of M‐PVDF and the interaction of these groups with GO sheets. Since GO often amplified gas barrier properties of polymers, such increscent would be appreciable. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46271.
Regulating the arm structure of star‐shaped polycarboxylate superplasticizers as a means to enhance cement paste workability
Authors: Zhao Yangyang , Nian Fuwei , Pang Hao , Huang Jianheng , Zhao Hongwei , Wang Kun , Liao Bing
Published: February 2018

Star‐shaped superplasticizers, which incorporated polyol ester with unsaturated bond at their cores and bore comb‐type structures as their arms were synthesized via esterification‐copolymerization in aqueous phase from pentaerythritol, acrylic acid (AA), and isopentenyl oxy poly(ethylene glycol ether) (TPEG). The monomer ratios of AA and TPEG were varied and comonomer sodium methallyl sulfonate (SMAS) bearing short side chains was added to regulate the arm structure of star‐shaped polycarboxylate superplasticizers (SPCEs). The effects of the SPCEs on cement paste were investigated and the cement dispersion as well as early hydration mechanism were explored. As a main result, SPCEs with SMAS and certain molar ratios for anchoring groups and PEO side‐chains in their arm structure exhibited good paste dispersion and fluidity retention, which also delayed the early hydration process and prolonged both the initial and the final setting time. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46312.
Messunsicherheit und ihr Einfluss auf „wesentliche Merkmale“ von mechanischen Befestigungen
Authors: Zeman Oliver , Schwenn Michael , Bergmeister Konrad
Published: February 2018

Laboratorien, die Prüfungen oder Kalibrierungen durchführen, müssen nach ISO 17025 in der Lage sein, die Messunsicherheit bei Durchführung der Prüfungen zu bestimmen. Dies kann durch exakte rechnerische Ermittlung als auch durch geeignete Schätzung erfolgen. Alle Beiträge, welche für die Ermittlung der Messunsicherheit von Bedeutung sind, müssen nach sinnvollem Ermessen dazu herangezogen werden. Im spezifischen Fall der Prüfung von nachträglichen Befestigungen in Beton nach European Assessment Document EAD 330232 bzw. EOTA Technical Report 048 wird ebenfalls die Einhaltung der Anforderungen der ISO 17025 hinsichtlich messtechnischer Rückführung und der Bestimmung der Messunsicherheit gefordert.

In diesem Beitrag wird aus der Sicht von Prüfstellen im Bereich der Befestigungstechnik untersucht, inwiefern die Messunsicherheit auf Grundlage der normativ bzw. in Regelwerken vorgegebenen Genauigkeitsanforderungen an die Prüfeinrichtungen einen Einfluss auf die wesentlichen Merkmale („essential characteristics“) hat. Es wird gezielt auf die Bestimmung der Beiträge zum Messunsicherheitsbudget bei der Bestimmung einer zentrischen Auszugslast Fu eingegangen, wobei für den Anwender die theoretische mathematische Herleitung der Empfindlichkeitsfaktoren c gezeigt wird.

Für einen vereinfachten Ansatz wird eine Hilfestellung zur Abschätzung des Einflusses des Betonuntergrunds und der Verankerungstiefe auf die Messunsicherheit bei Ermittlung der Auszugslasten gegeben.
Surviving Starvation: AMPK Protects Germ Cell Integrity by Targeting Multiple Epigenetic Effectors
Authors: Demoinet Emilie , Roy Richard
Published: February 2018

Acute starvation can have long‐term consequences that are mediated through epigenetic change. Some of these changes are affected by the activity of AMP‐activated protein kinase (AMPK), a master regulator of cellular energy homeostasis. In Caenorhabditis elegans, the absence of AMPK during a period of starvation in an early larval stage results in developmental defects following their recovery on food, while many of them become sterile. Moreover, the loss of AMPK during this quiescent period results in transgenerational phenotypes that can become progressively worse with each successive generation. Our recent data describe a chromatin‐based mechanism of how AMPK mediates adjustment to acute starvation in the germ cells, however, the heritable aspect of this AMPK mutant phenotype remains unresolved. Here, we explore how AMPK might affect this process and speculate how the initial transcription that occurs in the germ cells may adversely affect subsequent germline gene expression and/or genomic integrity.
Metabolite identification of the antimalarial naphthoquine using liquid chromatography–tandem high‐resolution mass spectrometry in combination with multiple data‐mining tools
Authors: Sun Yanhong , Wang Shuqi , Ji Jianbo , Zhai Guangxi , Xing Jie
Published: February 2018

Naphthoquine (NQ) is one of important partner drugs of artemisinin‐based combination therapy (ACT), which is recommended for the treatment of uncomplicated Plasmodium falciparum. NQ shows a high cure rate after a single oral administration. It is absorbed quickly (time to peak concentration 2–4 h) and has a long elimination half‐life (255 h). However, the metabolism of NQ has not been clarified. In this work, the metabolite profiling of NQ was studied in six liver microsomal incubates (human, cynomolgus monkey, beagle dog, mini pig, rat and CD1 mouse), seven recombinant CYP enzymes (1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4) and rat (plasma, urine, bile and feces) using liquid chromatography tandem high‐resolution LTQ‐Orbitrap mass spectrometry (HRMSn) in conjunction with online hydrogen/deuterium exchange. The biological samples were pretreated by protein precipitation and solid‐phase extraction. For data processing, multiple data‐mining tools were applied in tandem, i.e. background subtraction and followed by mass defect filter. NQ metabolites were characterized by accurate MS/MS fragmentation characteristics, the hydrogen/deuterium exchange data and cLogP simulation. As a result, five phase I metabolites (M1–M5) of NQ were characterized for the first time. Two metabolic pathways were involved: hydroxylation and N‐oxidation. This study demonstrates that LC‐HRMSn in combination with multiple data‐mining tools in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs.
In vivo microdialysis with ultra performance liquid chromatography–mass spectrometry for analysis of tetramethylpyrazine and its interaction with borneol in rat brain and blood
Authors: Liao Weiguo , Huang Xiaojie , Yin Yongxin , Liu Bin , Zhu Runzhi
Published: February 2018

Tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic cerebrovascular disease. However, the mechanism of TMP and how to increase its bioavailability need to be further explored. In our study, an in vivo microdialysis sampling technique coupled with ultra‐performance liquid chromatography–mass spectrometry method was developed to investigate the pharmacokinetic properties of TMP and its interaction with different doses of borneol (BO) in rats. Linearity of TMP in brain and blood dialysates exhibited good linear relationships over the concentration range of 0.991–555.14 ng/mL. The specificity, linearity, accuracy, precision, matrix effect and stability were within acceptable ranges. The results demonstrated that BO had a marked impact on the pharmacokinetic properties of TMP. After co‐administration, the areas under the concentration–time curve (AUC) of TMP in brain and blood were significantly increased. Meanwhile, the peak concentration of TMP in brain was also enhanced. The AUCBrain/AUCBlood of TMP, increased from 44% to 56 and 60.8% after co‐administration with BO (15 and 30 mg/kg). The pharmacodynamic results showed that TMP co‐administration with BO enhanced the cerebral blood flow during the period of ischemia and reduced the infarct volume. Overall, it might be an effective way to treat stroke to use TMP co‐administered with BO.
Parent survey finds more than 5% of children have ADHD, with preschool prevalence increasing
Authors: Knopf Alison
Published: February 2018

About one‐quarter of the children with attention‐deficit/hyperactivity disorder (ADHD) received no treatment — no medication, no behavioral treatment — for the condition in 2016, according to research based on the National Survey of Children's Health (NSCH). In 2016, about 6.1 million children ages 2–17 in the United States had ever received a diagnosis of ADHD, and of these, about 5.4 million currently had the disorder. Of those, almost two‐thirds (62.0%) were taking medication, and 46.7% had received behavioral treatment for ADHD in the past year. The survey found that the prevalence of diagnosed and treated ADHD among preschool children is increasing.
Primed Conversion: The New Kid on the Block for Photoconversion
Authors: Mohr Manuel Alexander , Pantazis Periklis
Published: February 2018

In 2015, a novel way to convert photoconvertible fluorescent proteins was reported that uses the intercept of blue and far‐red light instead of traditional violet or near‐UV light illumination. This Minireview describes and contrasts this distinct two‐step mechanism termed primed conversion with traditional photoconversion. We provide a comprehensive overview of what is known to date about primed conversion and focus on the molecular requirements for it to take place. We provide examples of its application to axially confined photoconversion in complex tissues as well as super‐resolution microscopy. Further, we describe why and when it is useful, including its advantages and disadvantages, and give an insight into potential future development in the field.
An Optical Sensor Array Discriminates Syrups and Honeys
Authors: Bojanowski N. Maximilian , Hainer Felix , Bender Markus , Seehafer Kai , Bunz Uwe H. F.
Published: February 2018

We report a cross‐reactive sensor array, combining a two‐component probe system based upon three viologen substituted boronic acids and a poly(aryleneethynylene) (PAE) and an additional number of simple PAEs alone. This combined system discriminates 27 different honeys in aqueous solution, according to patterns in fluorescence intensity modulation, using linear discriminant analysis for data processing. The fluorescence turn‐on array detects saccharide composition, while the PAEs discriminate trace colored components in the honeys.
Anion Recognition in Water, Including Sulfate, by a Bicyclam Bimetallic Receptor: A Process Governed by the Enthalpy/Entropy Compensatory Relationship
Authors: Boiocchi Massimo , Bonizzoni Marco , Ciarrocchi Carlo , Fabbrizzi Luigi , Invernici Michele , Licchelli Maurizio
Published: February 2018

The dimetallic system [CuII2(L)]4+ contains two facing equivalent metallocyclam subunits and incorporates ambidentate anions, mono‐ (halides) and poly‐atomic (sulfate), which bridge the two CuII centres. Isothermal titration calorimetry (ITC) experiments in water showed that the log K values of the inclusion equilibria for halides and sulfate varied over a restricted interval (3.6±0.2), which indicated lack of selectivity and that similarity of ΔG° values resulted from the unbalanced contribution of the ΔH° and TΔS° terms: the more favourable the one, the less favourable the other. In particular, a linear dependence of ΔH° and TΔS° was observed (a typical enthalpy/entropy compensatory diagram), which assigned a major role to hydration terms: 1) a more hydrated anion resulted in a more endothermic dehydration process; and 2) a larger number of water molecules released to the solution resulted in a more positive TΔS°. Limiting cases refer to the complexation 1) of the poorly hydrated iodide (highly exothermic process, entropically disfavoured), and 2) of the highly hydrated sulfate (moderately endothermic process, entropically very favoured). Anion receptors operating in water belong to two main domains: 1) those exhibiting positive ΔH° and positive TΔS° (+/+ signature), and 2) those displaying the opposite behaviour: (−/− signature). The receptor investigated herein connects the two domains, along the ΔH°/TΔS° straight line, thanks to the hidden role of the versatile metal–anion interaction.
Probing Magnetic‐Exchange Coupling in Supramolecular Squares Based on Reducible Tetrazine‐Derived Ligands
Authors: Lemes Maykon A. , Stein Hilarie N. , Gabidullin Bulat , Robeyns Koen , Clérac Rodolphe , Murugesu Muralee
Published: February 2018

Reducible 3,6‐bis(3,5‐dimethyl‐pyrazolyl)1,2,4,5‐tetrazine was employed to isolate supramolecular air‐stable [Co4] and [Zn4] squares, which were achieved via careful selection of counterions rather than the use of reducing agents. Magnetic susceptibility studies revealed a strong radical‐CoII exchange coupling (Jrad‐Co/hc=−118 cm−1, −2J formalism) with a spin ground state of ST=4, whereas the unreduced analogue revealed negligible coupling between the Co centers (JCo‐Co/hc=−0.64 cm−1). Radical–radical coupling was also probed in the [Zn4] congener, which led to Jrad‐rad/hc=−15.9(5) cm−1. These results highlight the versatile air‐stable coordination chemistry of tetrazine and the importance of exploiting easily reducible delocalized radical to promote strong exchange coupling between spin carriers.
Cover Image, Volume 75, Issue 2
Authors: Feng Yan , Mitran Sorin
Published: February 2018

ON THE BACK COVER: The cover image, by Yan Feng and Sorin Mitran, is based on the Research Article Data‐driven reducedorder model of microtubule mechanics, DOI: 10.1002/cm.21419.

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Trajectories of income and social benefits for mothers and fathers of children with cancer: A national cohort study in Sweden
Authors: Hiyoshi Ayako , Montgomery Scott , Bottai Matteo , Hovén Emma I.
Published: February 2018

BACKGROUND

The contribution of different income sources from work and social benefits to trajectories of income for the parents of children with cancer has not been empirically investigated.

METHODS

Using Swedish registers, parents of children with an incidence cancer diagnosis between 2004 and 2009 were identified and matched with parents of children without cancer (reference parents). A total of 20,091 families were followed from the year before the diagnosis to a maximum of 8 years. Generalized linear models estimated the ratios of mean incomes from work and social benefits and of its total.

RESULTS

Around the time of the child's cancer diagnosis, the total income was on average up to 6% higher among the mothers of children with cancer compared with reference mothers, but no differences were noted among fathers. Income from work dropped to the lowest level around the time of a cancer diagnosis, with swift recovery noted for fathers but not for mothers. Sickness and childcare‐related benefits were up to 6 times larger for the parents of children with cancer than reference parents. As social benefits diminished after approximately 3 years, the total income of mothers of children with cancer became lower than that of reference mothers, and the gap widened over time.

CONCLUSIONS

Social benefits appeared to ease the financial burden during the years around a cancer diagnosis. However, mothers experienced persistently lower income after benefits diminished. Experiences differed by single‐parent versus dual‐parent households, the survival of the child with cancer, and other relevant characteristics. Further investigation is needed for potential long‐term consequences for mothers, including their career and future pension in retirement. Cancer 2018;124:1492‐500. © 2018 American Cancer Society.
Effects of fibroblast‐myocyte coupling on the sinoatrial node activity: A computational study
Authors: Karpaev Alexey A. , Syunyaev Roman A. , Aliev Rubin R.
Published: February 2018

While the sinoatrial node (SAN) is structurally heterogeneous, most computer simulations of electrical activity take into account SAN pacemaker cells only. Our aim was to investigate how fibroblasts affect the SAN activity. We simulated the rabbit sinoatrial node accounting for differences between central and peripheral pacemaker cells, and for fibroblast‐myocyte electrical coupling. We have observed that only if fibroblast‐myocyte coupling is taken into account, (1) action potential is initiated in the central part of the SAN (within 1.2 mm of the center of simulated tissue); otherwise, leading centers are located on the periphery; (2) few (1 to 6) leading centers initiate action potential in the SAN; otherwise, we observed more than 8 leading centers; (3) acetylcholine superfusion results in a shift of leading centers toward the SAN periphery; and (4) sinus pauses up to 1.9 second follow acetylcholine superfusion. We observed negligible effect of fibroblast‐myocyte coupling on the period of SAN activation. We conclude that fibroblast‐myocyte coupling may explain action potential initiation and propagation from the center of the SAN observed in experimental studies, while atrial load on the peripheral SAN fails to explain this fact.
Detection of prohibited substances in equine hair by ultra‐high performance liquid chromatography–triple quadrupole mass spectrometry – application to doping control samples
Authors: Gray B. , Viljanto M. , Menzies E. , Vanhaecke L.
Published: February 2018

The detection of drugs in human hair samples has been performed by laboratories around the world for many years and the matrix is popular in disciplines, such as workplace drug testing. To date, however, hair has not become a routinely utilised matrix in sports drug detection. The analysis of hair samples offers several potential advantages to doping control laboratories, not least of which are the greatly extended detection window and the ease of sample collection and storage.

This article describes the development, validation, and utilisation of a sensitive ultra‐high performance liquid chromatography–triple quadrupole mass spectrometry (UHPLC–MS/MS) method for the detection of 50 compounds. This provides significantly improved coverage for those analytes which would be of particular interest if detected in hair, such as anabolic steroid esters and selective androgen receptor modulators (SARMs).

Qualitative validation of the method resulted in estimated limits of detection as low as 0.1 pg/mg for the majority of compounds, with all being detected at 2 pg/mg or below. The suitability of the method for the detection of prohibited substances in incurred material was demonstrated by the successful detection of several compounds, such as stanozolol, boldenone undecylenate, clenbuterol, and GW‐501516, in genuine equine hair samples. Estimated concentrations of the detected substances ranged from 0.27 to 8.6 pg/mg. The method has been shown to be fit‐for‐purpose for routine screening of equine hair samples by the analysis of over 400 genuine hair samples.
Quantification of rainfall interception in the high Andean tussock grasslands
Authors: Ochoa‐Sánchez A. , Crespo P. , Célleri R.
Published: February 2018

The páramo ecosystem provides most of the water for the tropical Andean highlands in South America. Although the comprehension of this environment has increased lately, there remains an urgent need to quantify the processes involved in the hydrological cycle. Interception loss (IL) is one of the least studied processes in the páramo, and more generally, in grasslands globally. The main objective of this study was to quantify IL at event scale by estimating it indirectly from precipitation (P) and effective rainfall (ER). Furthermore, the following questions were assessed: (a) how much of the P becomes ER? (b) what is the impact on IL calculations of using a rain gauge instead of a disdrometer? (c) which meteorological variables are related to the IL process? and (d) is it possible to estimate IL from meteorological variables? High percentages of IL in relation to P were found (10–100%). The canopy storage capacity of tussock grasses was approximately 2 mm. The disdrometer observations led to more accurate results than the rain gauge observations because only the disdrometer registers light precipitation, horizontal precipitation, and drizzle that increases the amount of P, ER, and IL estimates. Also, we found that IL is more strongly correlated with P; and IL can be estimated with a multiple linear regression (R2 = 0.9) from P and relative humidity for events where 1.7 < P < 8.5 mm. These findings show the important role of IL in the páramo and provide a stepping stone to modelling of water resources.
Human cardiomyocyte calcium handling and transverse tubules in mid‐stage of post‐myocardial‐infarction heart failure
Authors: Høydal Morten Andre , Kirkeby‐Garstad Idar , Karevold Asbjørn , Wiseth Rune , Haaverstad Rune , Wahba Alexander , Stølen Tomas L. , Contu Riccardo , Condorelli Gianluigi , Ellingsen Øyvind , Smith Godfrey L. , Kemi Ole J. , Wisløff Ulrik
Published: February 2018

Aims

Cellular processes in the heart rely mainly on studies from experimental animal models or explanted hearts from patients with terminal end‐stage heart failure (HF). To address this limitation, we provide data on excitation contraction coupling, cardiomyocyte contraction and relaxation, and Ca2+ handling in post‐myocardial‐infarction (MI) patients at mid‐stage of HF.

Methods and results

Nine MI patients and eight control patients without MI (non‐MI) were included. Biopsies were taken from the left ventricular myocardium and processed for further measurements with epifluorescence and confocal microscopy. Cardiomyocyte function was progressively impaired in MI cardiomyocytes compared with non‐MI cardiomyocytes when increasing electrical stimulation towards frequencies that simulate heart rates during physical activity (2 Hz); at 3 Hz, we observed almost total breakdown of function in MI. Concurrently, we observed impaired Ca2+ handling with more spontaneous Ca2+ release events, increased diastolic Ca2+, lower Ca2+ amplitude, and prolonged time to diastolic Ca2+ removal in MI (P < 0.01). Significantly reduced transverse‐tubule density (−35%, P < 0.01) and sarcoplasmic reticulum Ca2+ adenosine triphosphatase 2a (SERCA2a) function (−26%, P < 0.01) in MI cardiomyocytes may explain the findings. Reduced protein phosphorylation of phospholamban (PLB) serine‐16 and threonine‐17 in MI provides further mechanisms to the reduced function.

Conclusions

Depressed cardiomyocyte contraction and relaxation were associated with impaired intracellular Ca2+ handling due to impaired SERCA2a activity caused by a combination of alteration in the PLB/SERCA2a ratio and chronic dephosphorylation of PLB as well as loss of transverse tubules, which disrupts normal intracellular Ca2+ homeostasis and handling. This is the first study that presents these mechanisms from viable and intact cardiomyocytes isolated from the left ventricle of human hearts at mid‐stage of post‐MI HF.
Cyclometalated Ruthenium, Osmium, and Iridium Complexes Bridged by an NCN–Pyrene–NCN Derivative – Synthesis and Comparison of Optical, Thermal, and Electrochemical Properties
Authors: Zych Dawid , Slodek Aneta , Golba Sylwia , Krompiec Stanisław
Published: February 2018

New ruthenium (Ru), osmium (Os), and iridium (Ir) complexes bridged by the cyclometalating ligand 1,3,6,8‐tetra[4‐(2,2‐dimethylpropyloxy)‐2‐pyridyl]pyrene and containing terminal 4′‐(4‐metoxynaphthalene‐1‐yl)‐2,2′:6′,2′′‐terpyridine ligands were synthesized, and the effects of the metal center on their diverse properties were evaluated. Thermal measurements showed that the obtained complexes retain high thermal stabilities. The structural properties were evaluated through density functional theory (DFT) calculations. Furthermore, spectroscopic and theoretical studies through time‐dependent DFT (TD‐DFT) calculations revealed the characters of the transitions; metal‐to‐ligand charge‐transfer (MLCT) excitations are predominant for Ru and Os and weakly observed for Ir. Electrochemical studies revealed considerable differences between the complexes.
Controlling the Structures of Lanthanide Complexes in Self‐Assemblies with Tripodal Ligands
Authors: Hamacek Josef , Vuillamy Alexandra
Published: February 2018

Invited for the cover of this issue is Josef Hamacek from CNRS Orléans, France. The cover image shows the spontaneous self‐assembly of tripodal ligands and lanthanide cations.
Real‐time Monitoring of Exocytotic Glutamate Release from Single Neuron by Amperometry at an Enzymatic Biosensor
Authors: Qiu Quan‐Fa , Zhang Fu‐Li , Tang Yun , Zhang Xin‐Wei , Jiang Hong , Liu Yan‐Ling , Huang Wei‐Hua
Published: February 2018

Glutamate (Glu) is recognized as a vital neurotransmitter released via vesicular exocytosis and plays important roles in many physiological processes. Microelectrode amperometry has become a powerful method to study the secreted electroactive biochemicals via exocytosis, however, there was no means for direct monitoring of exocytosis of the non‐electroactive Glu so far. Herein, we developed an enzymatic micro‐biosensor by co‐modification of glutamate oxidase (GluOx) and Pt nanoparticles (Pt NPs) on the surface of a carbon fiber microelectrode. The Glu was enzymatically transformed by GluOx to an electroactive product, H2O2, which was then electrochemically detected by the Pt NPs. The prominent catalytic activity of enzyme and micrometer scale of microelectrode endow the sensor with high sensitivity and spatio‐temporal resolution, allowing real‐time monitoring Glu exocytosis from single hippocampal varicosities. The results demonstrate the capability of this biosensor in monitoring and quantification of the quantal release of neurotransmitter Glu, indicating its great potential in exploring the cellular mechanism of neuron communication and synaptic plasticity.
A meta‐analysis approach with filtering for identifying gene‐level gene–environment interactions
Authors: Wang Jiebiao , Liu Qianying , Pierce Brandon L. , Huo Dezheng , Olopade Olufunmilayo I. , Ahsan Habibul , Chen Lin S.
Published: February 2018

There is a growing recognition that gene–environment interaction (G × E) plays a pivotal role in the development and progression of complex diseases. Despite a wealth of genetic data on various complex diseases/traits generated from association and sequencing studies, detecting G × E via genome‐wide analysis remains challenging due to power issues. In genome‐wide G × E studies, a common strategy to improve power is to first conduct a filtering test and retain only the genetic variants that pass the filtering step for subsequent G × E analyses. Two‐stage, multistage, and unified tests have been proposed to jointly consider the filtering statistics in G × E tests. However, such G × E tests based on data from a single study may still be underpowered. Meanwhile, large‐scale consortia have been formed to borrow strength across studies and populations. In this work, motivated by existing single‐study G × E tests with filtering and the needs for meta‐analysis G × E approaches based on consortia data, we propose a meta‐analysis framework for detecting gene‐based G × E effects, and introduce meta‐analysis‐based filtering statistics in the gene‐level G × E tests. Simulations demonstrate the advantages of the proposed method—the ofGEM test. We apply the proposed tests to existing data from two breast cancer consortia to identify the genes harboring genetic variants with age‐dependent penetrance (i.e., gene–age interaction effects). We develop an R software package ofGEM for the proposed meta‐analysis tests.
Manifold decoding for neural representations of face viewpoint and gaze direction using magnetoencephalographic data
Authors: Kuo Po‐Chih , Chen Yong‐Sheng , Chen Li‐Fen
Published: February 2018

The main challenge in decoding neural representations lies in linking neural activity to representational content or abstract concepts. The transformation from a neural‐based to a low‐dimensional representation may hold the key to encoding perceptual processes in the human brain. In this study, we developed a novel model by which to represent two changeable features of faces: face viewpoint and gaze direction. These features are embedded in spatiotemporal brain activity derived from magnetoencephalographic data. Our decoding results demonstrate that face viewpoint and gaze direction can be represented by manifold structures constructed from brain responses in the bilateral occipital face area and right superior temporal sulcus, respectively. Our results also show that the superposition of brain activity in the manifold space reveals the viewpoints of faces as well as directions of gazes as perceived by the subject. The proposed manifold representation model provides a novel opportunity to gain further insight into the processing of information in the human brain.
Modelling the dopamine and noradrenergic cell loss that occurs in Parkinson's disease and the impact on hippocampal neurogenesis
Authors: Ermine Charlotte M. , Wright Jordan L. , Frausin Stefano , Kauhausen Jessica A. , Parish Clare L. , Stanic Davor , Thompson Lachlan H.
Published: February 2018

Key pathological features of Parkinson's Disease (PD) include the progressive degeneration of midbrain dopaminergic (DA) neurons and hindbrain noradrenergic (NA) neurons. The loss of DA neurons has been extensively studied and is the main cause of motor dysfunction. Importantly, however, there are a range of ‘non‐movement’ related features of PD including cognitive dysfunction, sleep disturbances and mood disorders. The origins for these non‐motor symptoms are less clear, but a possible substrate for cognitive decline may be reduced adult‐hippocampal neurogenesis, which is reported to be impaired in PD. The mechanisms underlying reduced neurogenesis in PD are not well established. Here we tested the hypothesis that NA and DA depletion, as occurs in PD, impairs hippocampal neurogenesis. We used 6‐hydroxydopamine or the immunotoxin dopamine‐β‐hydroxylase‐saporin to selectively lesion DA or NA neurons, respectively, in adult Sprague Dawley rats and assessed hippocampal neurogenesis through phenotyping of cells birth‐dated using 5‐bromo‐2′‐deoxyuridine. The results showed no difference in proliferation or differentiation of newborn cells in the subgranular zone of the dentate gyrus after NA or DA lesions. This suggests that impairment of hippocampal neurogenesis in PD likely results from mechanisms independent of, or in addition to degeneration of DA and NA neurons.
Differential contributions of Ca2+‐activated K+ channels and Na+/K+‐ATPases to the generation of the slow afterhyperpolarization in CA1 pyramidal cells
Authors: Tiwari Manindra Nath , Mohan Sandesh , Biala Yoav , Yaari Yoel
Published: February 2018

In many types of CNS neurons, repetitive spiking produces a slow afterhyperpolarization (sAHP), providing sustained, intrinsically generated negative feedback to neuronal excitation. Changes in the sAHP have been implicated in learning behaviors, in cognitive decline in aging, and in epileptogenesis. Despite its importance in brain function, the mechanisms generating the sAHP are still controversial. Here we have addressed the roles of M‐type K+ current (IM), Ca2+‐gated K+ currents (ICa(K)'s) and Na+/K+‐ATPases (NKAs) current to sAHP generation in adult rat CA1 pyramidal cells maintained at near‐physiological temperature (35 °C). No evidence for IM contribution to the sAHP was found in these neurons. Both ICa(K)'s and NKA current contributed to sAHP generation, the latter being the predominant generator of the sAHP, particularly when evoked with short trains of spikes. Of the different NKA isoenzymes, α1‐NKA played the key role, endowing the sAHP a steep voltage‐dependence. Thus normal and pathological changes in α1‐NKA expression or function may affect cognitive processes by modulating the inhibitory efficacy of the sAHP.
Nylon as an in vitro scaffold for three‐dimensional study of neural cells
Authors: Batth Aran , Thompson Ian
Published: February 2018

The requirement for improved modeling of cells in culture for study of cell‐to‐cell interactions has led to an increased focus on three‐dimensional (3D) in vitro models. In this study, NG108‐15 neural cells and rat sciatic nerve Schwann cells were successfully grown as monocultures and as a coculture on the biocompatible nylon mesh substrates. This has allowed proliferation and interactions between the two cell types to be monitored on the mesh over time. Electrophysiological recordings validated the NG108‐15 neural cell differentiation which confirmed the similarity of recorded action potentials in two‐dimensional culture environments. A variety of assays have been used, demonstrating the use of nylon as an appropriate substrate for neural cell in vitro studies, and nylon can easily be imaged using inverted microscopy. These studies confirm the suitability of the nylon 3D culture presented for modeling neural cell behavior. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1575–1584, 2018.
Blood–brain barrier and its function during inflammation and autoimmunity
Authors: Sonar Sandip Ashok , Lal Girdhari
Published: February 2018

The blood–brain barrier (BBB) is an important physiologic barrier that separates CNS from soluble inflammatory mediators and effector immune cells from peripheral circulation. The optimum function of the BBB is necessary for the homeostasis, maintenance, and proper neuronal function. The clinical and experimental findings have shown that BBB dysfunction is an early hallmark of various neurologic disorders ranging from inflammatory autoimmune, neurodegenerative, and traumatic diseases to neuroinvasive infections. Significant progress has been made in the understanding of the regulation of BBB function under homeostatic and neuroinflammatory conditions. Several neurologic disease-modifying drugs have shown to improve the BBB function. However, they have a broad-acting immunomodulatory function and can increase the risk of life-threatening infections. The recent development of in vitro multicomponent 3-dimensional BBB models coupled with fluidics chamber as well as a cell-type specific reporter and knockout mice gave a new boost to our understanding of the dynamics of the BBB. In the review, we discuss the current understanding of BBB composition and recent findings that illustrate the critical regulatory elements of the BBB function under physiologic and inflammatory conditions, and also suggested the strategies to control BBB structure and function.
Negative regulators that mediate ocular immune privilege
Authors: Taylor Andrew W , Ng Tat Fong
Published: February 2018

The ocular microenvironment has adapted several negative regulators of inflammation to maintain immune privilege and health of the visual axis. Several constitutively produced negative regulators within the eye TGF-β2, α-melanocyte stimulating hormone (α-MSH), Fas ligand (FasL), and PD-L1 standout because of their capacity to influence multiple pathways of inflammation, and that they are part of promoting immune tolerance. These regulators demonstrate the capacity of immune privilege to prevent the activation of inflammation, and to suppress activation of effector immune cells even under conditions of ocular inflammation induced by endotoxin and autoimmune disease. In addition, these negative regulators promote and expand immune cells that mediate regulatory and tolerogenic immunity. This in turn makes the immune cells themselves negative regulators of inflammation. This provides for a greater understanding of immune privilege in that it includes both molecular and cellular negative regulators of inflammation. This would mean that potentially new approaches to the treatment of autoimmune disease can be developed through the use of molecules and cells as negative regulators of inflammation.
“NOTA‐PRGD2 and NODAGA‐PRGD2: Bioconjugation, characterization, radiolabelling, and design space”
Authors: Salvé Mallory , Avohou Hermane T. , Monbaliu Jean‐Christophe M. , Lebrun Pierre , Lemaire Christian , Damblon Christian , de Tullio Pascal , Hubert Philippe , Hustinx Roland , Luxen André
Published: February 2018

This work reports on the development of amide bond bioconjugation for the production of ‐NOTA and ‐NODAGA PRGD2 using batch strategy and microfluidic reactor technology. The final radiolabelling step was fully optimized using Design of Experiments and Design Space approaches, hence targeting robust labelling yields in routine. Optimal labelling conditions were defined in sodium acetate buffer as 168 μg/mL peptide concentration, 4.9 pH, 47.5°C temperature, and 12.5‐minute reaction time. Upon optimization, the Gallium‐68 radiolabelling was fully automated. All the work was designed to be compliant to the GMP environment and to support the pharmaceutical scale‐up.
Radioiodination and bioevaluation of rolipram as a tracer for brain imaging: In silico study, molecular modeling and gamma scintigraphy
Authors: Sanad M.H. , Farag A.B. , Salama Dina H.
Published: February 2018

Brain imaging is considered one of the most fruitful applications of radioisotope scanning. Rolipram, a selective phospodiesterase‐4 inhibitor, has been labeled using [125I] with chloramine‐T (Ch‐T) as an oxidizing agent. Factors, such as the amount of substrate, pH, the amount of oxidizing agent, temperature, and the reaction time, have been systematically studied to optimize the iodination process. In addition, bio‐distribution studies have indicated that the brain uptake of [125I]iodorolipram is 7.6 ± 0.33 injected dose/g organ at 10 minutes post‐injection, which cleared from the brain with time until it reaches 1.30 ± 0.17% at 1 hour post‐injection. Therefore, iodorolipram could be considered as a potential, new selective radiotracer for brain imaging.
Long‐term evaluation (20 years) of the outcomes of coronally advanced flap in the treatment of single recession‐type defects
Authors: Pini Prato Giovan Paolo , Magnani Cristina , Chambrone Leandro
Published: February 2018

Background

Coronally advanced flap (CAF) has been considered as one of the most predictable and versatile root coverage procedures. Thus, the aims of this study are two‐fold: 1) to evaluate the long‐term outcomes following CAF in the treatment of gingival recession (GR); and 2) to explore the influence of several tooth/patient‐related factors on the stability of gingival margin at 5, 10, and 20 years after surgery.

Methods

Ninety‐four patients with 97 GR (73 Miller`s Class I and 24 Miller's Class III) were treated with CAF in a private practice between 1984 and 1996. Recession depth (RD), probing depth (PD), keratinized tissue (KT) width and patient/tooth‐associated variables were recorded for each GR at baseline, 1 year, 5 years, 10 years, 15 years and 20 years after surgery. Parametric, non‐parametric, and logistic regression statistics were used throughout the study

Results

A total of 72 patients with 72 GR were available for analysis at the 20‐year follow‐up examination (final patients’ dropout rate = 23.4%). Statistically significant improvements were found for RD in all evaluations (P < 0.05). Little more than a half (56%) of the sites treated with CAF did not display RD changes between the short‐term (i.e., 1 year) and long‐term (i.e., 20 years) examinations. Overall, mean root coverage (MRC) decreased from 68.59% to 56.11%. The achievement of complete root coverage (CRC) 1 year after treatment was associated to GR not presenting interdental tissue loss (P = 0.001), the root condition (i.e., lack of non‐carious cervical lesion [step] – P < 0.001), an attached KT band ≥ 2 mm (P = 0.019), and baseline RD (P = 0.020). GR recurrence seemed to be influenced by age, RD at 1‐year follow‐up, sites displaying an attached KT < 2 mm and interdental tissue loss.

Conclusions

The aging process, the condition of the interdental periodontal tissue, and the presence of an attached KT band < 2 mm seem to be negative factors influencing the stability of the gingival margin during the 20‐year observation period.
Antimicrobial and Cytotoxic Properties of Bisquaternary Ammonium Bromides of Different Spacer Length
Authors: Łudzik Katarzyna , Kustrzepa Kinga , Kowalewicz‐Kulbat Magdalena , Kontek Renata , Kontek Bogdan , Wróblewska Aneta , Jóźwiak Małgorzata , Lulo Daria
Published: February 2018

A group of cationic gemini surfactants (bisquaternary ammonium bromides) with different spacer chain lengths (8–6–8, 8–7–8, 8–8–8, 8–9–8) was investigated, paying special attention to antimicrobial and the cytotoxic properties as well as their antimicrobial activity during long‐term storage. It was shown that the compounds investigated exhibit excellent antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus) and Gram‐negative bacteria (Pseudomonas aeruginosa) as well as antifungal properties (Candida albicans). The gemini surfactants tested had the differential level of cytotoxicity against normal lymphocytes. It was shown that the spacer chain length plays an important role in antibacterial activity and influences the cytotoxicity. The gemini surfactants with shorter spacer chain length, that had higher critical micelle concentration, showed generally weaker antibacterial properties, but on the other hand, these exhibited lower level of cytotoxicity. Furthermore, the aqueous solution of gemini surfactants exhibited the same antimicrobial activity even after 3 months.
Effect of castration and carcass suspension method on the quality and fatty acid profile of beef from male dairy cattle
Authors: Nian Yingqun , Allen Paul , Harrison Sabine M , Kerry Joseph P
Published: February 2018

BACKGROUND

The use of bulls rather than steers for beef production offers some considerable advantages; however, the eating quality of bull beef is an issue of marketing concern. This study assessed the physicochemical characteristics of young Holstein–Friesian (HF) bull and steer beef. Steer carcasses were suspended by the Achilles tendon (AS) and by pelvic suspension (PS).

RESULTS

HF steer beef had higher redness, yellowness and chroma values, whereas bulls had higher ultimate pH and darker muscle. Warner–Bratzler shear force, cook loss at different ageing times, moisture, and insoluble and total collagen were higher for HF bull beef, whereas intramuscular fat, soluble collagen and collagen solubility were higher for steer beef. HF steer beef had a higher proportion of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), whereas bull beef had higher proportions of polyunsaturated fatty acids (PUFA), PUFA/SFA and n‐6/n‐3 PUFA ratios. In comparison to AS, PS increased redness and chroma after 24 h blooming; PS improved tenderness up to 7 days of ageing and accelerated the ageing process.

CONCLUSION

For young dairy cattle, steer beef would likely have superior eating quality but a relatively less favourable nutritional fatty acid profile to bull beef. Suspension method affected the tenderness and colour intensity of dairy steer beef at different ageing times. © 2018 Society of Chemical Industry
Classification of tongue cancer resection and treatment algorithm
Authors: Mannelli Giuditta , Arcuri Francesco , Agostini Tommaso , Innocenti Marco , Raffaini Mirco , Spinelli Giuseppe
Published: February 2018

Background and Objectives

Reconstruction of tongue cancer defects is challenging due to the complex anatomy and physiology of the tongue. Here, we classify patterns of tongue tissue loss and describe a treatment algorithm for achieving good functional and oncologic outcomes.

Methods

We retrospectively reviewed 50 tongue squamous‐cell carcinomas surgically treated between January 2010‐June 2015. Cancer resection and tongue reconstruction were stratified according to the missing anatomical subunits.

Results

A type 1 defect is a unilateral and marginal defect, not crossing the midline, and not extending to the posterior‐third of the tongue. Type 2 involves the two‐anterior‐thirds of the mobile body, not crossing the midline, without posterior‐third evolvement. Type 3 involves the two‐anterior‐thirds of the mobile body of the tongue with contralateral extension. Type 4 extends to the tongue base. Type 5 defect comprises any of the previous defects along with involvement of the floor of the mouth. Type 2 and 3 defects were the most common. Microvascular reconstruction was performed in 23 out of 50 patients. Complications included infection, partial necrosis, dehiscence, and microvascular thrombosis.

Conclusions

Our classification system and treatment algorithm represent a reliable method of addressing management of tongue defects.