bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐Fullerene Acceptor‐Based Bulk Heterojunction Polymer Solar Cells: Engineering the Nanomorphology via Processing Additives
Authors: Ren Guoqiang , Ahmed Eilaf , Jenekhe Samson A.
Published: August 2011

The performance of bulk heterojunction solar cells made from blends of a non‐fullerene acceptor, N,N′‐bis(2‐ethylhexyl)‐2,6‐bis(5″‐hexyl‐[2,2′;5′,2″]terthiophen‐5yl)‐1,4,5,8‐naphthalene diimide (NDI‐3TH), and poly(3‐hexylthiophene) (P3HT) donor is enhanced 10‐fold by using a processing additive in conjunction with an electron‐blocking and a hole‐blocking buffer layers. The power conversion efficiency of P3HT:NDI‐3TH solar cells improves from 0.14% to 1.5% by using a processing additive (1,8‐diiodooctane) at an optimum concentration of 0.2 vol%, which is far below the 2‐3 vol% optimum concentrations found in polymer/fullerene systems. TEM and AFM imaging show that the size and connectivity of the NDI‐3TH domains in the phase‐separated P3HT:NDI‐3TH blends vary strongly with the concentration of the processing additive. These results demonstrate, for the first time, that processing additives can be effective in the optimization of the morphology and performance of bulk heterojunction polymer solar cells based on non‐fullerene acceptors.
Loss of junctophilin‐3 contributes to huntington disease‐like 2 pathogenesis
Authors: Seixas Ana I. , Holmes Susan E. , Takeshima Hiroshi , Pavlovich Amira , Sachs Nancy , Pruitt Jennifer L. , Silveira Isabel , Ross Christopher A. , Margolis Russell L. , Rudnicki Dobrila D.
Published: August 2011

Objective:

Huntington disease‐like 2 (HDL2) is a progressive, late onset autosomal dominant neurodegenerative disorder, with remarkable similarities to Huntington disease (HD). HDL2 is caused by a CTG/CAG repeat expansion. In the CTG orientation, the repeat is located within the alternatively spliced exon 2A of junctophilin‐3 (JPH3), potentially encoding polyleucine and polyalanine, whereas on the strand antisense to JPH3, the repeat is in frame to encode polyglutamine. The JPH3 protein product serves to stabilize junctional membrane complexes and regulate neuronal calcium flux. We have previously demonstrated the potential pathogenic properties of JPH3 transcripts containing expanded CUG repeats. The aim of this study was to test the possibility that loss of JPH3 expression or expanded amino acid tracts also contribute to HDL2 pathogenesis.

Methods:

Transcripts from the HDL2 locus, and their protein products, were examined in HDL2, HD, and control frontal cortex. The effect of loss of Jph3 was examined in mice with partial or complete loss of Jph3.

Results:

Bidirectional transcription occurs at the HDL2 locus, although expression of antisense transcripts with expanded CAG repeats is limited. Protein products with expanded amino acid tracts were not detected in HDL2 brain. However, JPH3 transcripts and full‐length JPH3 protein are decreased in HDL2 brain, and Jph3 hemizygous and null mice exhibit abnormal motor function.

Interpretation:

Our results suggest that the pathogenic mechanism of HDL2 is multifactorial, involving both a toxic gain of function of JPH3 RNA and a toxic loss of JPH3 expression. Ann Neurol 2012;71:245–257
Angiogenin variants in Parkinson disease and amyotrophic lateral sclerosis
Authors: van Es Michael A. , Schelhaas Helenius J. , van Vught Paul W. J. , Ticozzi Nicola , Andersen Peter M. , Groen Ewout J. N. , Schulte Claudia , Blauw Hylke M. , Koppers Max , Diekstra Frank P. , Fumoto Katsumi , LeClerc Ashley Lyn , Keagle Pamela , Bloem Bastiaan R. , Scheffer Hans , van Nuenen Bart F. L. , van Blitterswijk Marka , van Rheenen Wouter , Wills Anne‐Marie , Lowe Patrick P. , Hu Guo‐fu , Yu Wenhao , Kishikawa Hiroko , Wu David , Folkerth Rebecca D. , Mariani Claudio , Goldwurm Stefano , Pezzoli Gianni , Van Damme Philip , Lemmens Robin , Dahlberg Caroline , Birve Anna , Fernández‐Santiago Rubén , Waibel Stefan , Klein Christine , Weber Markus , van der Kooi Anneke J. , de Visser Marianne , Verbaan Dagmar , van Hilten Jacobus J. , Heutink Peter , Hennekam Eric A. M. , Cuppen Edwin , Berg Daniela , Brown Robert H. , Silani Vincenzo , Gasser Thomas , Ludolph Albert C. , Robberecht Wim , Ophoff Roel A. , Veldink Jan H. , Pasterkamp R. Jeroen , de Bakker Paul I. W. , Landers John E. , van de Warrenburg Bart P. , van den Berg Leonard H.
Published: August 2011

Objective:

Several studies have suggested an increased frequency of variants in the gene encoding angiogenin (ANG) in patients with amyotrophic lateral sclerosis (ALS). Interestingly, a few ALS patients carrying ANG variants also showed signs of Parkinson disease (PD). Furthermore, relatives of ALS patients have an increased risk to develop PD, and the prevalence of concomitant motor neuron disease in PD is higher than expected based on chance occurrence. We therefore investigated whether ANG variants could predispose to both ALS and PD.

Methods:

We reviewed all previous studies on ANG in ALS and performed sequence experiments on additional samples, which allowed us to analyze data from 6,471 ALS patients and 7,668 controls from 15 centers (13 from Europe and 2 from the USA). We sequenced DNA samples from 3,146 PD patients from 6 centers (5 from Europe and 1 from the USA). Statistical analysis was performed using the variable threshold test, and the Mantel‐Haenszel procedure was used to estimate odds ratios.

Results:

Analysis of sequence data from 17,258 individuals demonstrated a significantly higher frequency of ANG variants in both ALS and PD patients compared to control subjects (p = 9.3 × 10−6 for ALS and p = 4.3 × 10−5 for PD). The odds ratio for any ANG variant in patients versus controls was 9.2 for ALS and 6.7 for PD.

Interpretation:

The data from this multicenter study demonstrate that there is a strong association between PD, ALS, and ANG variants. ANG is a genetic link between ALS and PD. ANN NEUROL 2011;70:964–973
Zuverlässige und effiziente Konjugation von Biomolekülen über Huisgen‐Azid‐Alkin‐Cycloadditionen
Authors: Lallana Enrique , Riguera Ricardo , Fernandez‐Megia Eduardo
Published: August 2011

Die CuI‐katalysierte Azid‐Alkin‐Cycloaddition (CuAAC) ist ein etabliertes Biokonjugationsverfahren für Proteine, Nucleinsäuren und Polysaccharide. Der Einsatz von Cu führt aber zu einigen Problemen, hauptsächlich in Form von oxidativen Zersetzungsprozessen durch reaktive Sauerstoffspezies sowie einer Kontamination der Probe mit Cu. Dieser Kurzaufsatz stellt die wichtigsten Fortschritte bei der effizienten und schonenden Funktionalisierung von Biomakromolekülen über CuAAC und die Cu‐freie ringspannungsvermittelte Azid‐Alkin‐Cycloaddition (SPAAC) vor.
Polyethylene glycol‐polyethylenimine‐tetrachloroplatinum (IV): A novel conjugate with good abilities of antitumor and gene delivery
Authors: Zhao Lu , Xu Fujian , Chen Huan , Tang Guping , Hu Xiurong
Published: August 2011

It is much importance to develop novel multifunctional delivery systems for the combination therapy of drug and gene. In this work, a novel conjugate, polyethylene glycol‐polyethylenimine‐tetrachloroplatinum (IV) (PEG‐PEI‐Pt), with good abilities of antitumor and gene delivery was proposed by combining PEG (Mw 3400 Da), low molecular weight PEI (Mw 800 Da), and tetrachloroplatinum (IV). The antitumoral and gene transfection activities of PEG‐PEI‐Pt were analyzed in many tumor (A549, A375, HepG‐2, HuH‐7, and B16 cells) and normal (COS‐7 cells) cell lines. Similar to cisplatin (one platinum anticancer drug), PEG‐PEI‐Pt showed much higher sensitivity in tumor cells than in normal cells. More importantly, PEG‐PEI‐Pt had a potential to treat drug‐resistant tumors. Almost no transfection efficiency was observed for PEI (Mw 800 Da) and PEG‐PEI. Very interestingly, PEG‐PEI‐Pt could condense plasmid DNA efficiently, and exhibited good transfection efficiency in B16, HepG‐2, A375 and COS‐7 cells, comparable to even higher than PEI 25 kDa. In addition, PEG‐PEI‐Pt could also effectively deliver siRNA into the cytoplasm of tumor cells. With the good antitumoral and gene delivery abilities, PEG‐PEI‐Pt may have a great potential for combination therapy of drug and gene. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Inclusion complex of cantharidin with β‐cyclodextrin: Preparation, characterization, in vitro and in vivo evaluation
Authors: Dang Yun‐Jie , An Lin‐Na , Hu Chunhui , Zhu Chun‐Yan
Published: August 2011

Because of low aqueous solubility and slow dissolution rate, cantharidin has a low oral bioavailability. Our research aims to prepare the inclusion complex of cantharidin and β‐cyclodextrin (β‐CD) and accomplish characterization, in vitro and in vivo evaluation. CA‐β‐CD inclusion complex was prepared by saturated solution method. The CA was demonstrated by HPLC in vitro experiment and by GC‐MS in vivo experiment. CA‐β‐CD inclusion complex was characterized by differential scanning calorimetry (DSC), X‐ray diffractometry (XRD), and nuclear magnetic resonance (NMR). Through complexation with β‐CD, the solubility of CA in neutral aqueous solution was improved significantly. CA‐β‐CD inclusion complex also shows a significantly improved dissolution rate in comparison with free CA. Comparison of the pharmacokinetics between CA‐β‐CD inclusion complex and free CA was performed in rats. The in vivo results show that CA‐β‐CD inclusion complex has earlier tmax, higher Cmax, and higher bioavailability than free CA after oral dosing. By comparing the AUC0–t of CA and CA‐β‐CD inclusion complex, the relative bioavailability of CA‐β‐CD inclusion complex to free CA was 506.3%, which highlighted the evidence of significantly improved bioavailability of formulation of CA with β‐CD. Thus, this β‐CD‐based drug delivery system should be an effective oral dosage form to improve oral bioavailability of CA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Femoral Morphology and Femoropelvic Musculoskeletal Anatomy of Humans and Great Apes: A Comparative Virtopsy Study
Authors: Morimoto Naoki , De León Marcia S. Ponce , Nishimura Takeshi , Zollikofer Christoph P.E.
Published: August 2011

Scheme of virtual dissection (virtopsy). Volume data visualization was performed for CT data of a formalin‐preserved juvenile chimpanzee (id: AIMUZH‐7283) to visualize muscles and skeleton. See Figure 2B and 2C in Morimoto et al., on page 1437, in this issue.
What does the g‐index really measure?
Authors: De Visscher Alex
Published: August 2011

It was argued recently that the g‐index is a measure of a researcher's specific impact (i.e., impact per paper) as much as it is a measure of overall impact. While this is true for the productive “core” of publications, it can be argued that the g‐index does not differ from the square root of the total number of citations in a bibliometrically meaningful way when the entire publication list is considered. The R‐index also has a tendency to follow total impact, leaving only the A‐index as a true measure of specific impact. The main difference between the g‐index and the h‐index is that the former penalizes consistency of impact whereas the latter rewards such consistency. It is concluded that the h‐index is a better bibliometric tool than is the g‐index, and that the square root of the total number of citations is a convenient measure of a researcher's overall impact.
When transparency and collaboration collide: The USA Open Data program
Authors: Peled Alon
Published: August 2011

President Obama's inaugural flagship Open Data program emphasizes the values of transparency, participation, and collaboration in governmental work. The Open Data performance data analysis, published here for the first time, proposes that most federal agencies have adopted a passive–aggressive attitude toward this program by appearing to cooperate with the program while in fact effectively ignoring it. The analysis further suggests that a tiny group of agencies are the only “real players” in the Data.gov web arena. This research highlights the contradiction between Open Data's transparency goal (“All data must be freed”) and federal agencies' goal of collaborating with each other through data trade. The research also suggests that agencies comprehended that Open Data is likely to exacerbate three critical, back‐office data‐integration problems: inclusion, confusion, and diffusion. The article concludes with a proposal to develop an alternative Federal Information Marketplace (FIM) to incentivize agencies to improve data sharing.
Sulfonic and Phosphonic Acid and Bifunctional Organic–Inorganic Hybrid Membranes and Their Proton Conduction Properties
Authors: Sel Ozlem , Azais Thierry , Maréchal Manuel , Gébel Gérard , Laberty‐Robert Christel , Sanchez Clément
Published: August 2011

Hybrid organic–inorganic approaches are used for the synthesis of bifunctional proton exchange membrane fuel cell (PEMFC) membranes owing to their ability to combine the properties of a functionalized inorganic network and an organic thermostable polymer. We report the synthesis of both sulfonic and phosphonic acid functionalized mesostructured silica networks into a poly(vinylidenefluoride‐co‐hexafluoropropylene) (poly(VDF‐co‐HFP) copolymer. These membranes, containing different amounts of phosphonic acid and sulfonic acid groups, have been characterized using FTIR and NMR spectroscopy, SA‐XRD, SAXS, and electrochemical techniques. The proton conductivity of the bifunctional hybrid membranes depends strongly on hydration, increasing by two orders of magnitude over the relative humidity (RH) range of 20 to 100 %, up to a maximum of 0.031 S cm−1 at 60 °C and 100 % RH. This value is interesting as only half of the membrane conducts protons. This approach allows the synthesis of a porous SiO2 network with two different functions, having SO3H and PO3H2 embedded in a thermostable polymer matrix.
How ubiquitination regulates the TGF‐β signalling pathway: New insights and new players
Authors: Soond Surinder M. , Chantry Andrew
Published: August 2011

Ubiquitination of protein species in regulating signal transduction pathways is universally accepted as of fundamental importance for normal development, and defects in this process have been implicated in the progression of many human diseases. One pathway that has received much attention in this context is transforming growth factor‐beta (TGF‐β) signalling, particularly during the regulation of epithelial‐mesenchymal transition (EMT) and tumour progression. While E3‐ubiquitin ligases offer themselves as potential therapeutic targets, much remains to be unveiled regarding mechanisms that culminate in their regulation. With this in mind, the focus of this review highlights the regulation of the ubiquitination pathway and the significance of a recently described group of NEDD4 E3‐ubiquitin ligase isoforms in the context of TGF‐β pathway regulation. Moreover, we now broaden these observations to incorporate a growing number of protein isoforms within the ubiquitin ligase superfamily as a whole, and discuss their relevance in defining a new ‘iso‐ubiquitinome’.
Laccase mediator systems for eco‐friendly production of medium‐density fiberboard (MDF) on a pilot scale: Physicochemical analysis of the reaction mechanism
Authors: Euring Markus , Rühl Martin , Ritter Nina , Kües Ursula , Kharazipour Alireza
Published: August 2011

Increasing prices of petrochemical resins and possible harmful formaldehyde emissions from conventionally produced wood composites have resulted in increased interest in enzymatic binder systems as environmentally friendly alternatives for gluing lignocellulosic products. In this study, laccase mediator systems (LMSs) were used to activate lignin on wood fiber surfaces in the pilot‐scale production of medium‐density fiberboard (MDF) using a dry process. Three different mediators were applied: 4‐hydroxybenzoic acid (HBA), 1‐hydroxybenzotriazole (HBT), and acetosyringone (AS) of which HBA performed best. The mechanical properties of the manufactured boards produced with thermomechanical pulp (TMP) fibers, laccase, and HBA fulfilled all required European standards for wood‐based panels. Oxygen consumption rates of the different LMSs and 13C NMR spectroscopy results for treated TMP fibers were obtained for qualitative and quantitative analysis of lignin activation. The results show that reactions were most effective within the first 30 min of incubation. Oxygen consumption was fastest and highest for the LMS using HBA. 13C NMR spectroscopy indicated the highest decrease of aromatic groups in the wood fiber lignin with this LMS. The data correlated well with the quality of the MDF. The required enzymatic reaction times allowed direct integration of the LMS into standard MDF production techniques. The results indicate that application of LMSs has a high potential for environmentally friendly MDF production.
Data management as bibliography
Authors: Buckland Michael
Published: August 2011

Editor's Summary

A critical element in the products of research projects is the data set, largely treated as a marginal appendage to the written record. With the requirement for data management plans in grant proposals to the National Science Foundation and National Institutes of Health, the issue of managing research data sets is gaining attention. Sharing primary data enables a greater return on the original investment, expanded discovery and fertilization of ideas across disciplines. The major impediment is lack of an infrastructure to archive non‐textual data sets, in addition to hurdles including locating data, deterioration, format standardization, permission for use and suitability. It is essential that institutional policies recognize data sets as a key product of intellectual work worthy of inclusion in a bibliography. This must be followed by action to promote their preservation, metadata enrichment, cross‐lingual interoperability, geographic and temporal coding and data provenance and to contend with changes over time.
Crystal Structures of Novel Allosteric Peptide Inhibitors of HIV Integrase Identify New Interactions at the LEDGF Binding Site
Authors: Rhodes David I. , Peat Thomas S. , Vandegraaff Nick , Jeevarajah Dharshini , Newman Janet , Martyn John , Coates Jonathan A. V. , Ede Nicholas J. , Rea Philip , Deadman John J.
Published: August 2011

An optimised method of solution cyclisation gave us access to a series of peptides including SLKIDNLD (2). We investigated the crystallographic complexes of the HIV integrase (HIV‐IN) catalytic core domain with 13 of the peptides and identified multiple interactions at the binding site, including hydrogen bonds with residues Thr125 and Gln95, that have not previously been described as being accessible within the binding site. We show that the peptides inhibit the interaction of lens epithelium‐derived growth factor (LEDGF) with HIV‐IN in a proximity AlphaScreen assay and in an assay for the LEDGF enhancement of HIV‐IN strand transfer. The interactions identified represent a potential framework for the development of new HIV‐IN inhibitors.
New Promising Iridium Catalyst for Toluene Hydrogenation
Authors: Zieliński Michał , Pietrowski Mariusz , Wojciechowska Maria
Published: August 2011

The use of an iridium active phase and magnesium fluoride as a support allowed us to obtain new catalysts of high activities in the hydrogenation of toluene. The Ir/MgF2catalyst was four times more active than the iridium system supported on commercial Al2O3. The nature of iridium precursors [H2IrCl6or Ir4(CO)12] and catalyst pretreatment conditions (reduction or oxidation/reduction) appeared to have a clear effect on the activity of Ir/MgF2catalysts. For the catalysts obtained from iridium carbonyl, the highest activity was obtained after direct reduction of the catalysts, whereas for the catalysts obtained from hexachloroiridium acid, the highest activity was obtained after reduction of the preliminary oxidized catalysts.
Water‐ and Acid‐Mediated Excited‐State Intramolecular Proton Transfer and Decarboxylation Reactions of Ketoprofen in Water‐Rich and Acidic Aqueous Solutions
Authors: Li Ming‐De , Yeung Chi Shun , Guan Xiangguo , Ma Jiani , Li Wen , Ma Chensheng , Phillips David Lee
Published: August 2011

We present an investigation of the decarboxylation reaction of ketoprofen (KP) induced by triplet excited‐state intramolecular proton transfer in water‐rich and acidic solutions. Nanosecond time‐resolved resonance Raman spectroscopy results show that the decarboxylation reaction is facile in aqueous solutions with high water ratios (water/acetonitrile≥50 %) or acidic solutions with moderate and strong acid concentration. These experimental results are consistent with results from density functional theory calculations in which 1) the activation energy barriers for the triplet‐state intramolecular proton transfer and associated decarboxylation process become lower when more water molecules (from one up to four molecules) are involved in the reaction system and 2) perchloric acid, sulfuric acid, and hydrochloric acid can shuttle a proton from the carboxyl to carbonyl group through an initial intramolecular proton transfer of the triplet excited state, which facilitates the cleavage of the CC bond, thus leading to the decarboxylation reaction of triplet state KP. During the decarboxylation process, the water molecules and acid molecules may act as bridges to mediate intramolecular proton transfer for the triplet state KP when KP is irradiated by ultraviolet light in water‐rich or acidic aqueous solutions and subsequently it generates a triplet‐protonated carbanion biradical species. The faster generation of triplet‐protonated carbanion biradical in acidic solutions than in water‐rich solutions with a high water ratio is also supported by the lower activation energy barrier calculated for the acid‐mediated reactions versus those of water‐molecule‐assisted reactions.
High‐Separation Performance of Chromatographic Capillaries Coated with MOF‐5 by the Controlled SBU Approach
Authors: Münch Alexander S. , Seidel Jürgen , Obst Anja , Weber Edwin , Mertens Florian O. R. L.
Published: August 2011

Recently developed MOF surface‐coating techniques, the controlled SBU approach (CSA) for the generation of MOF‐5, and the use of self‐assembled monolayers have been combined to generate a wall‐bonded, crosslinked stationary phase for gas chromatographic capillary columns displaying excellent performance in the separation of natural gas components. The chromatographic performance of this new type of column has been compared to the state‐of‐the‐art solution for this separation problem, namely a coated silica column of the porous layer open tubular (PLOT) type. Chromatographic parameters such as separation, resolution, and tailing factors, as well as plate numbers and heights in the case of isothermal operation, have been determined. Kinetic and thermodynamic parameters characterizing the analyte–stationary phase interaction have been determined for various C1–C4 analytes.
Simultaneous Detection of Intracellular Tumor mRNA with Bi‐Color Imaging Based on a Gold Nanoparticle/Molecular Beacon
Authors: Qiao Guangming , Gao Yuan , Li Na , Yu Zhengze , Zhuo Linhai , Tang Bo
Published: August 2011

The successful treatment of most cancers depends on early detection. Tumor mRNA as a specific marker provides new avenues to monitor tumor progression in the early stages and assesses response to treatment. However, single tumor mRNA testing usually yields “false positive” results because cancer is associated with multiple tumor mRNA. It is indispensable to develop simple and effective approaches for the detection of multiple tumor mRNA. In this study, we used a combination of tumor‐specific mRNA markers to avoid the inherent limitations associated with the single‐marker technique. A gold nanoparticle (AuNP) was assembled with a bi‐molecular beacon (bi‐MB), and termed AuNP/bi‐MB, which simultaneously targeted to two types of tumor mRNA in breast cancer cells. This imaging agent could prevent effectively false positive results and provide comprehensive and dependable information for the early detection of cancer. It would be beneficial to identify the stage of tumor progression and assess treatment decisions with the real‐time detection of the relative expression levels of tumor mRNA in cancer cells. This strategy would offer an appealing approach toward the early detection of cancer by using multianalysis of tumor mRNA.
Highly Efficient Control of Thrombin Activity by Multivalent Nanoparticles
Authors: Hsu Chia‐Lun , Chang Huan‐Tsung , Chen Chao‐Tsen , Wei Shih‐Chun , Shiang Yen‐Chun , Huang Chih‐Ching
Published: August 2011

We have demonstrated that the incorporation of sulfated galactose acid (sulf‐Gal) into thrombin‐binding‐aptamer (TBA)‐conjugated gold nanoparticles (TBA–AuNPs) enables highly effective inhibition of thrombin activity toward fibrinogen. AuNP bioconjugates (TBA15/TBA29/sulf‐Gal–AuNPs) were prepared from 13 nm AuNPs, 15‐mer thrombin‐binding aptamer (TBA15), 29‐mer thrombin‐binding aptamer (TBA29), and sulf‐Gal. The numbers of TBA and sulf‐Gal molecules per AuNP proved to have a strong impact on inhibitory potency. The best results were observed for 15‐TBA15/TBA29/sulf‐Gal–AuNPs (with 15 TBA15 and 15 TBA29 molecules per AuNP), which, because of their particularly flexible conformation and multivalency, exhibited ultrahigh binding affinity toward thrombin (Kd=3.4×10−12 M) and thus extremely high anticoagulant (inhibitory) potency. Compared to the case without inhibitors (the “normal” value), their measured thrombin clotting time (TCT) was 91 times longer, whereas for TBA15 alone it was only 7.2 times longer. Their anticoagulant activity was suppressed by TBA‐complementary‐sequence (cTBA)‐modified AuNPs (cTBA15/cTBA29–AuNPs) at a rate that was 20 times faster than that of free cTBA15/cTBA29. Thus, easily prepared, low‐cost, multivalent AuNPs show great potential for biomedical control of blood clotting.
Ruthenium(IV)‐Catalyzed Isomerization of the CC Bond of O‐Allylic Substrates: A Theoretical and Experimental Study
Authors: Varela‐Álvarez Adrián , Sordo José A. , Piedra Estefanía , Nebra Noel , Cadierno Victorio , Gimeno José
Published: August 2011

A general mechanism to rationalize RuIV‐catalyzed isomerization of the CC bond in O‐allylic substrates is proposed. Calculations supporting the proposed mechanism were performed at the MPWB1K/6‐311+G(d,p)+SDD level of theory. All experimental observations in different solvents (water and THF) and under different pH conditions (neutral and basic) can be interpreted in terms of the new mechanism. Theoretical analysis of the transformation from precatalyst to catalyst led to structural identification of the active species in different media. The experimentally observed induction period is related to the magnitudes of the energy barriers computed for that process. The theoretical energy profile for the catalytic cycle requires application of relatively high temperatures, as is experimentally observed. Participation of a water molecule in the reaction coordinate is mechanistically essential when the reaction is carried out in aqueous medium. The new mechanistic proposal helped to develop a new experimental procedure for isomerization of allyl ethers to 1‐propenyl ethers under neutral aqueous conditions. This process is an unique example of efficient and selective catalytic isomerization of allyl ethers in aqueous medium.
Unified Syntheses of Cavicularin and Riccardin C: Addressing the Synthesis of an Arene Adopting a Boat Configuration
Authors: Kostiuk Sarah L. , Woodcock Timothy , Dudin Leo F. , Howes Peter D. , Harrowven David C.
Published: August 2011

Concise syntheses of the natural products cavicularin (ten steps) and riccardin C (seven steps) are reported. Key features of the new synthetic route are a convergent strategy to assemble acyclic precursors and a sequence of regioselective reduction and halogenation steps to facilitate Wittig macrocyclisation and transannular ring contraction reactions.
Relationships between the stereochemistry and biological activity of fungal phytotoxins
Authors: Evidente Antonio , Andolfi Anna , Cimmino Alessio
Published: August 2011

Toxins produced by phytopathogenic fungi assume great importance because of their involvement in several plant diseases. Although such pathogens are known to have seriously damaged crops, forest, and environmental resources, they represent a very important tool to develop new environmentally friendly herbicides and fungicides. This review deals with the relationships between the biological activity of some phytotoxins produced by pathogenic fungi for major forest plants and for damaging weeds and their stereochemistry. In particular, the methods used to determine their relative and/or absolute configuration will be illustrated. These include the application of Mosher's and Murata's methods, X‐ray diffractometric analysis, circular dichroism, and the use of computational methods to determine the theoretical optical rotatory power as well as the CD spectrum. The importance of determining the absolute configuration to achieve the total synthesis of some phytotoxins, interesting for their potential practical application, is also discussed. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Searching for a good candidate to perform a chiral nuclear magnetic resonance experiment in disordered phase: A study of 8,9‐difluoro‐P‐hexahelicene
Authors: Monaco Guglielmo , Zanasi Riccardo
Published: August 2011

Calculations of nuclear magnetic shielding polarizabilities of the P‐hexahelicene and 8,9‐difluoro‐P‐hexahelicene molecules have been accomplished at the CTOCD‐DZ2/6‐31G(d,p) level. Pseudoscalars of the nuclear magnetic shielding polarizability are the largest reported so far for second‐row atoms. The rf voltage generated by the rotating chiral electric polarization, induced by the permanent magnetic dipole moment of the 19F nuclei of the 8,9‐difluoro‐P‐hexahelicene and by the spectrometer's magnetic field, is predicted to be ≈10 nV, that is, detectable with modern equipments. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Role of polyproline II conformation in human tropoelastin structure
Authors: Bochicchio Brigida , Pepe Antonietta
Published: August 2011

In this review, we present a comprehensive overview of the molecular studies on human tropoelastin domains accomplished by Tamburro and co‐workers in the last decade. The used approach is the reductionist approach applied to human tropoelastin and is based on the observation that the tropoelastin gene exhibits a cassette‐like organization, with a regular alternation of cross‐linking and hydrophobic domains putatively responsible for the elasticity of the protein. The peculiar structure of human tropoelastin gene prompted us to study the isolated domains encoded by the exons of tropoelastin, with the perspective to get deep insights into the structural properties of the whole protein. At the molecular level, the results clearly evidence large flexibility of the polypeptide chains in the hydrophobic domains, which oscillate between rather extended and folded conformations. An important role was assigned to poly‐proline II conformation considered as the hinge structure in the dynamic conformational equilibrium suggested for the hydrophobic domains. For the lysine‐rich cross‐linking domains, the structural studies exactly localized α‐helix along the polypeptide sequence. Furthermore, at supramolecular level, these studies showed that several domains are able to self‐assemble in two different aggregation patterns, the fibrous elastin‐like structure for some proline‐rich hydrophobic domains and the amyloid‐like for some glycine‐rich hydrophobic domains. Accordingly, the studies suggest that the reductionist approach was a valid tool for studying a complex protein, such as elastin, elucidating not only the structure but also the specific role played by its constituent domains. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
The critical main‐chain length for helix formation in water: Determined in a peptide series with alternating Aib and Ala residues exclusively and detected with ECD spectroscopy
Authors: Longo Edoardo , Moretto Alessandro , Formaggio Fernando , Toniolo Claudio
Published: August 2011

Critical main‐chain length for peptide helix formation in the crystal (solid) state and in organic solvents has been already reported. In this short communication, we describe our results aiming at assessing the aforementioned parameter in water solution. To this goal, we synthesized step‐by‐step by solution procedures a complete series of N‐terminally acetylated, C‐terminally methoxylated oligopeptides, characterized only by alternating Aib and Ala residues, from the dimer to the nonamer level. All these compounds were investigated by electronic circular dichroism in the far‐UV region in water solution as a function of chemical structure, namely presence/absence of an ester moiety or a negative charge at the C‐terminus, and temperature. We find that the critical main‐chain lengths for 310‐ and α‐helices, although still formed to a limited extent, in aqueous solution are six and eight residues, respectively. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Geomorphological Impact Assessment on Groundwater Quality and Fluoride Genesis along the Bay of Bengal of Visakhapatnam District, Andhra Pradesh, India
Authors: Kumar Kotra Krishna
Published: August 2011

Geomorphological effects might not be the mere natural topographical changes but, their impact on groundwater quantity/quality would be an aspect of great concern. Especially the qualitative fluctuations in coastal region would suffer more than those observed in the elevated or the plains. The ease and severity would magnify from the anthropogenic activities and from the effects carried over from the uplands. To evaluate this, a study was conducted by collecting 44 water samples of bore and open well origin along the Bay of Bengal coast of Visakhapatnam district. Geochemical assessment was carried from the results of all major chemical constituents and geological data of the sampling stations. The expansive and correlative interpretation of the results yielded the mechanisms control the genesis of principle chemical species, present status, reserves, drainage pattern and the recent intrusion zones in the study area. The genesis and spatial distribution of fluoride was assessed due to sporadic reports of fluorosis in the district. Upon receiving the findings with suitable recommendations, the Groundwater Board and the civil society organizations widely published and the displayed the results for further action made the study a purposeful.
Rab8 GTPase as a regulator of cell shape
Authors: Peränen Johan
Published: August 2011

Endogenous Rab8 is found in dynamic cell structures like filopodia, lamellipodia, protrusions, ruffles, and primary cilia. Activation of Rab8 is linked to the formation of these actin containing structures, whereas inhibition of Rab8 affects negatively their appearance. The activity of Rab8 is controlled by specific guanine nucleotide exchange factors and GTPase activating proteins. Rab8 regulates a membrane recycling pathway that is linked to Arf6, EHD1, Myo5, and Rab11. A hypothesis is presented on the role of Rab8 in the formation of new cell surface domains. The review focuses on the function of Rab8 in cell migration, epithelial polarization, neuron differentiation, and ciliogenesis. © 2011 Wiley‐Liss, Inc.
Acute ovarian failure underestimates age‐specific reproductive impairment for young women undergoing chemotherapy for cancer
Authors: Letourneau Joseph M. , Ebbel Erin E. , Katz Patricia P. , Oktay Kutluk H. , McCulloch Charles E. , Ai Wei Z. , Chien A. Jo , Melisko Michelle E. , Cedars Marcelle I. , Rosen Mitchell P.
Published: August 2011

BACKGROUND:

The authors sought to describe the age‐specific impact of infertility and early menopause after chemotherapy among reproductive age women with cancer.

METHODS:

A total of 1041 women diagnosed with cancer between the ages of 18 and 40 years responded to a retrospective survey on reproductive health history. Five cancer types were included: leukemia, Hodgkin disease (HD), non‐Hodgkin lymphoma (NHL), breast cancer, and gastrointestinal(GI) cancer. Survey questions addressed acute ovarian failure (cessation of menses after treatment), early menopause (menopause before 45 years old), and infertility (failed conception). Logistic regression was used to determine the proportions of acute ovarian failure and infertility based on age at diagnosis. Censored data methods were used to determine the probability of early menopause.

RESULTS:

Six hundred twenty women received chemotherapy alone. The percentage reporting acute ovarian failure was 8%, 10%, 9%, and 5% for HD, NHL, breast cancer, and GI cancer, respectively. Acute ovarian failure increased significantly with age at diagnosis (P < .05). In subjects not reporting acute ovarian failure, the incidence of infertility was at least 40% at age 35 years and increased significantly with age at diagnosis in HD and breast cancer (P < .05). The estimated probability of early menopause was at least 25% at age 30 years and increased significantly with younger age at diagnosis in HD, NHL, and GI cancer (P < .05).

CONCLUSIONS:

For patients to receive appropriate counseling, it is important that they understand the potential increased risk of infertility and early menopause beyond that of acute ovarian failure. These findings can provide improved, age‐specific counseling regarding reproductive impairment for young women diagnosed with cancer. Cancer 2012;. © 2011 American Cancer Society.
Can a Proton be Encapsulated in Tetraamido/Diamino Quaternized Macrocycles in Aqueous Solution and Electric Field?
Authors: Jiang Nan , Ma Jing
Published: August 2011

The proton‐binding behavior of solvated tetraamido/diamino quaternized macrocyclic compounds with rigid phenyl and flexible phenyl bridges in the absence or presence of an external electric field is investigated by molecular dynamics simulation. The proton can be held through H‐bonding interactions with the two carbonyl oxygen atoms in macrocycles containing rigid (phenyl) and flexible (propyl) bridges. The solute–solvent H‐bonding interactions cause the macrocyclic backbones to twist to different extents, depending on the different bridges. The macrocycle with the rigid phenyl linkages folds into a cuplike shape due to π–π interaction, while the propyl analogue still maintains the ellipsoidal ringlike shape with just a slight distortion. The potential energy required for proton transfer is larger in the phenyl‐containing macrocycle than in the compound with propyl units. When an external electric field with a strength of 2.5 V nm−1 is exerted along the carbonyl oxygen atoms, a difference in proton encircling is exhibited for macrocycles with rigid and flexible bridges. In contrast to encapsulation of a proton in the propyl analogue, the intermolecular solute–solvent H‐bonding and intramolecular π–π stacking between the two rigid phenyl spacers leads to loss of the proton from the highly distorted cuplike macrocycle with phenyl bridges. The competition between intra‐ and intermolecular interactions governs the behavior of proton encircling in macrocycles.
Squalene – biochemistry, molecular biology, process biotechnology, and applications
Authors: Spanova Miroslava , Daum Günther
Published: August 2011

Squalene is a natural triterpene and an important intermediate of sterol and hopanoid biosynthesis in various types of cell from bacteria to human. Synthesis and further conversion of squalene are key steps in the metabolism of sterols and related components. Here we summarize the recent knowledge of squalene biochemistry, its molecular properties, and its physiological effects. We compare squalene biosynthetic pathways in different cell types and describe biotechnological strategies to isolate this lipid. Finally, applications of squalene in nutrition, pharmacy, and medicine are discussed.
Tetraols as Templates for the Synthesis of Large endo‐Functionalized Macrocycles
Authors: Stoltenberg Dennis , Lüthje Sonja , Winkelmann Ole , Näther Christian , Lüning Ulrich
Published: August 2011

Forty‐six‐ and fifty‐membered endo‐functionalized macrocycles were obtained by template syntheses with new stiff tetracyclic tetraols 10 and 11. Reaction of dialkenylatedboronic acids 1 with template molecules 10 and 11 generated preorganized bisboronic esters 18 and 19, which were cyclized by ring‐closing olefin metathesis. Resulting bimacrocycles 20 and 21 were obtained in ca. 60 % yield when alkenyl chains of sufficient lengths were used. The E/E, E/Z, and Z/Z mixtures were hydrogenated to give saturated bimacrocycles 24 and 25 in excellent yields. The removal of the tetraol templates was possible by hydrolysis in the presence of dimethyl sulfate, which was needed to trap the liberated template. Thus, bis‐endo‐boronic acids 27e and 27f were obtained. The relative stereochemistry of the diastereoisomeric templates and the bimacrocyclic nature of the cyclization products were proven by X‐ray structure analyses (for 12 and 26d).
Acid‐Base Equilibrium of 6‐Benzylaminopurine and Its 4‐Chloro and 4‐Methoxy Derivatives in Water‐Ethanol Solutions Studied by Voltammetry and Spectrophotometry
Authors: Serrano Núria , Holubova Sylvie , Trnkova Libuse
Published: August 2011

The apparent pKa values of 6‐benzylaminopurine (BAP) and its 4‐chloro‐6‐benzylaminopurine and 4‐methoxy‐6‐benzylaminopurine derivatives were determined in good agreement with voltammetric approaches and with spectrophotometry. Whereas at acidic pH values two overlapped reduction peaks on the mercury electrode were obtained, at more slightly alkaline solutions one reduction signal was measured not only for BAP but also for its derivatives. Furthermore, high scan rates, low ionic strength concentration and a high percentage of the organic solvent cause the best splitting of signals. For the detailed study of such a phenomenon, elimination voltammetry with linear scan (EVLS) was used concluding that the reasons of the peak splitting seem to be related to two different reduction mechanisms that take place on the electrode mainly controlled by adsorption.
Eph receptors and ephrins in neuron–astrocyte communication at synapses
Authors: Murai Keith K. , Pasquale Elena B.
Published: August 2011

Neuron–glia communication is essential for regulating the properties of synaptic connections in the brain. Astrocytes, in particular, play a critical and complex role in synapse development, maintenance, and plasticity. Likewise, neurons reciprocally influence astrocyte physiology. However, the molecular signaling events that enable astrocytes and neurons to effectively communicate with each other are only partially defined. Recent findings have revealed that Eph receptor tyrosine kinases and ephrins play an important role in contact‐dependent neuron–glia communication at synapses. Upon binding, these two families of cell surface‐associated proteins trigger bidirectional signaling events that regulate the structural and physiological properties of both neurons and astrocytes. This review will focus on the emerging role of Eph receptors and ephrins in neuron–astrocyte interaction at synapses and discuss implications for synaptic plasticity, behavior, and disease. © 2011 Wiley‐Liss, Inc.
THE EFFECT OF CHILDHOOD CONDUCT DISORDER ON HUMAN CAPITAL
Authors: Webbink Dinand , Vujić Sunčica , Koning Pierre , Martin Nicholas G.
Published: August 2011

This paper estimates the longer‐term effects of childhood conduct disorder on human capital accumulation and violent and criminal behavior later in life using data of Australian twins. We measure conduct disorder with a rich set of indicators based on diagnostic criteria from psychiatry. Using ordinary least squares and twin fixed effects estimation approaches, we find that early‐age (pre‐18) conduct disorder problems significantly affect both human capital accumulation and violent and criminal behavior over the life course. In addition, we find that conduct disorder is more deleterious if these behaviors occur earlier in life. Copyright © 2011 John Wiley & Sons, Ltd.
Regionalization of the probability of wet spells and rainfall persistence in the Basque Country (Northern Spain)
Authors: Fdez‐Arroyabe Hernáez Pablo , Martin‐Vide Javier
Published: August 2011

The following paper deals with the modelling of a 30‐year‐long daily rainfall time series (1965–1994) from 39 weather stations in the Basque Country region in Northern Spain. Markov chain models are used to explore the temporal rainfall patterns in the area and to characterize the persistence of daily rain in terms of the order of the discrete Markov process. The Markov models—theoretical probabilities—are fitted to the empirical probability of wet spells lasting one more day than a specific length in the time series under the assumption of three different values (1, 5 and 10 mm) of a minimum threshold. Markovian orders that first fit the empirical distributions are used to map the theoretical persistence of daily rainfall in the Basque Country area through the use of geostatistical interpolators. Markovian orders have been confirmed as remarkable stochastic models for fitting empirical distributions of wet spells in this area, ultimately being shown as a spatial representation of theoretical persistence. Copyright © 2011 Royal Meteorological Society
Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008
Authors: Harvey David J.
Published: August 2011

This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N‐ and O‐linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate‐protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest. © 2011 Wiley Periodicals, Inc. Mass Spec Rev 31:183–311, 2012