bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractWe 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

AbstractA 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

AbstractConcise 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

AbstractToxins 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

AbstractCalculations 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

AbstractIn 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

AbstractCritical 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

AbstractGeomorphological 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

AbstractEndogenous 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

AbstractBACKGROUND: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

AbstractThe 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

AbstractSqualene 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

AbstractForty‐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

AbstractThe 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

AbstractNeuron–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

SUMMARYThis 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

AbstractThe 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

AbstractThis 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