bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous occurrence of diarrhetic and paralytic shellfish poisoning toxins in Spanish mussels in 1993
Authors: Gago‐Martinez Ana , Rodriguez‐Vazquez José A. , Thibault Pierre , Quilliam Michael A. 
Published: June 2010

AbstractMussel aquaculture is an important industry for the Galician Rias, located in northwestern Atlantic coast of Spain. Since 1976 this region has been seriously affected by incidents of paralytic and diarrhetic shellfish poisoning (PSP and DSP). A particularly bad epidode occurred in 1993, when the toxic event lasted for an unusually long period. Many people were stricken ill with unusual symptoms. In this paper we report on the chemical analysis of toxic 1993 mussel samples, using the techniques of liquid chromatography and capillary electrophoresis coupled with mass spectrometry. These analyses revealed a very complex toxin profile, with both PSP and DSP toxins present. Two DSP toxins, okadaic acid and DTX2, were observed, while the primary PSP toxins were B1 and the decarbamoylated derivatives of saxitoxin, GTX2 and GTX3. Small amounts of saxitoxin and other as yet unidentified PSP toxins were observed.
Lichen acids as uncouplers of oxidative phosphorylation of mouse‐liver mitochondria
Authors: Abo‐Khatwa A. N. , Al‐Robai A. A. , Al‐Jawhari D. A. 
Published: June 2010

AbstractThree lichen acids—namely, (+)usnic acid, vulpinic acid, and atranorin—were isolated from three lichen species (Usnea articulata, Letharia vulpina, and Parmelia tinctorum, respectively). The effects of these lichen products on mice‐liver mitochondrial oxidative functions in various respiratory states and on oxidative phosphorylation were studied polarographically in vitro. The lichen acids exhibited characteristics of the 2,4‐dinitrophenol (DNP), a classical uncoupler of oxidative phosphorylation. Thus, they released respiratory control and oligomycin inhibited respiration, hindered ATP synthesis, and enhanced Mg2+‐ATPase activity. (+)Usnic acid at a concentration of 0.75 μM inhibited ADP/O ratio by 50%, caused maximal stimulation of both state‐4 respiration (100%) and ATPase activity (300%). Atranorin was the only lichen acid with no significant effect on ATPase. The uncoupling effect was dose‐dependent in all cases. The minimal concentrations required to cause complete uncoupling of oxidative phosphorylation were as follows: (+)usnic acid (1 μM), vulpinic acid, atranorin (5 μM) and DNP (50 μM). It was postulated that the three lichen acids induce uncoupling by acting on the inner mitochondrial membrane through their lipophilic properties and protonophoric activities.
Fluoroacetate content of some species of the toxic Australian plant genus, gastrolobium, and its environmental persistence
Authors: Twigg Laurie E. , King Dennis R. , Bowen Lynn H. , Wright Geoffrey R. , Eason Charles T. 
Published: June 2010

AbstractGas chromatography confirmed the relatively high concentrations of fluoroacetate found in toxic Gastrolobiums, a genus of indigenous Australian plants. Fluoroacetate concentration in these plants ranged from 01 to 3875 μg/g (ppm) dry weight, with young leaves and flowers containing the highest concentrations However, there was considerable intrastand variation between individual plants of at least two species with coefficients of variation ranging from 94% to 129%. Despite the high concentrations of fluoroacetate in many species, only one of nine soil samples collected from beneath these plants contained fluoroacetate None of the 16 water samples collected from nearby streams and catchment dams contained fluoroacetate. This suggests that fluoroacetate does not persist in this environment. Fluoroacetate was also found in the genus Nemcia, and very low levels of fluoroacetate (ng/g) were detected in the foodstuffs, tea and guar gum The latter indicates that other plant species may produce biologically insignificant amounts of fluoroacetate
A saporin‐insulin conjugate: Synthesis and biochemical characterization
Authors: Ippoliti Rodolfo , Lendaro Eugenio , Bellelli Andrea , Fiani Maria Luisa , Benedetti Pier Alberto , Evangelista Valtere , Brunori Maurizio 
Published: June 2010

AbstractSaporin, a single‐chain, non‐cytotoxic, ribosome‐inactivating protein from Saponaria officinalis, was chemically linked to the hormone insulin in a 1:1 complex. To follow by dynamic video microscopy the endocytosis and intracellular transport in vivo, a second covalent conjugate with a saporin derivative labelled with fluorescein isothiocyanate was also prepared. Both conjugates were characterized with reference to homogeneity, stoichiometry, optical spectroscopy and toxicity. Both were found to exhibit scarce toxicity toward both CHO and HEP G2 cells; optical video microscopy on living cells indicates that reduced toxicity may be (partly) due to a very limited binding of the saporin‐insulin conjugate to membrane receptors. These results suggest a strategy for new possible covalent conjugates of saporin with alternative and specific macromolecular carners
Analysis, separation, and bioassay of pyrrolizidine alkaloids from comfrey (symphytum officinale)
Authors: Couet Carole E. , Crews Colin , Hanley A. Bryan 
Published: June 2010

AbstractPyrrolizidine alkaloids have been linked to liver and lung cancers and a range of other deleterious effects. As with many natural toxicants, major problems arise in determining the effects of the different members of the class and the importance of various forms of ingestion. In this study we have investigated the levels of pyrrolizidine alkaloids in comfrey (Symphytum officinale), determined the levels in different parts of the plant and in herbal remedies, separated the alkaloids into two main groups— the principal parent alkaloids and the corresponding N‐oxides—and, finally, carried out a simple bioassay based upon the mutagenic capability of the separated compounds in a human cell line. We conclude that the part of the plant ingested is important in terms of alkaloid challenge and that the effect of two of the major groups of alkaloids individually is different from that of alkaloids in the whole plant extract.
Facile Functionalization and Phase Reduction Route of Magnetic Iron Oxide Nanoparticles for Conjugation of Matrix Metalloproteinase
Authors: Li Dan , Teoh Wey Yang , Djunaedi Diana , Gooding Jolen Justin , Selomulya Cordelia , Amal Rose 
Published: June 2010

AbstractA protocol for the simultaneous functionalization and phase reduction route of iron oxide magnetic nanoparticles (MNPs) and its further bioconjugation is presented. It was found that surface functionalization of maghemite (γ‐Fe2O3) nanoparticles with mercaptopropyltrimethoxysilane (MPTMS) under anoxic environment at above 80 °C promotes in situ conversion to magnetite (Fe3O4). Full conversion to Fe3O4, as probed by Mössbauer spectroscopy, with accompanied increase in the composite saturation magnetization, was achieved at 120 °C. By controlling the MPTMS concentration, the resultant silane‐MNPs morphology can be tuned from having homogeneous thin layer (<1 nm) to thick continuous silane with embedded MNP multicores. Likewise the amount of surface distal thiol moieties was dependent on the silanization conditions. The density of distal thiols (i.e., amount of thiol per surface area) and resultant aggregate size have direct impact on the attachment, as well as the activity and reusability of the conjugated matrix metalloproteinase (MMP‐2, using sulfo‐SMCC as crosslinker). The work has important implication to the field of magneto‐chemotherapeutics, where spatial control of conjugated active biomolecules under magnetic field and T2‐weighted MRI contrast can be achieved simultaneously.
Proteolytically Degradable Photo‐Polymerized Hydrogels Made From PEG–Fibrinogen Adducts
Authors: Dikovsky Daniel , Bianco‐Peled Havazelet , Seliktar Dror 
Published: June 2010

AbstractWe develop a biomaterial based on protein–polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate‐functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein–polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non‐cross‐linked and UV cross‐linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20 kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free‐radical polymerization cross‐linking reaction in the hydrogel precursor solution. As expected, the conjugated protein‐polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free‐radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross‐linking kinetics and stiffness of the cross‐linked hydrogel are highly influenced by the protein–polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein–polymer conjugates proves to be were different from those of the non‐conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG–protein adduct. A more complete understanding of the molecular complexities associated with this type of protein‐polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins.
Stable Non‐Covalent Large Area Patterning of Inert Teflon‐AF Surface: A New Approach to Multiscale Cell Guidance
Authors: Valle Francesco , Chelli Beatrice , Bianchi Michele , Greco Pierpaolo , Bystrenova Eva , Tonazzini Ilaria , Biscarini Fabio 
Published: June 2010

AbstractMicro‐ and nano‐patterning of cell adhesion proteins is demonstrated to direct the growth of neural cells, viz. human neuroblastoma SHSY5Y, at precise positions on a strongly antifouling substrate of technolological interest. We adopt a soft‐lithographic approach with oxygen plasma modified PDMS stamps to pattern human laminin on Teflon‐AF films. These patterns are based on the interplay of capillary forces within the stamp and non‐covalent intermolecular and surface interactions. Remarkably, they remain stable for several days upon cell culture conditions. The fabrication of substrates with adjacent antifouling and adhesion‐promoting regions allows us to reach absolute spatial control in the positioning of neuroblastoma cells on the Teflon‐AF films. This patterning approach of a technologically‐relevant substrate can be of interest in tissue engineering and biosensing.
Homogene Gold‐Katalyse jenseits von Vermutungen und Annahmen – charakterisierte Intermediate
Authors: Hashmi A. Stephen K. 
Published: June 2010

AbstractDie Gold‐Katalyse ist ein sehr aktives Gebiet im Feld der Katalyseforschung. Wöchentlich werden neue Reaktionen publiziert, oft werden erstaunliche Konnektivitätsänderungen beobachtet, die Zahl der Anwendungen in der Totalsynthese steigt …︁ – aber was sind die Mechanismen dieser Reaktionen? Fundierte Informationen können aus dem Wissen über Zwischenstufen dieser Reaktionen erhalten werden.
Formtreue organische Käfigverbindungen durch dynamische Bildung kovalenter Bindungen
Authors: Mastalerz Michael 
Published: June 2010

AbstractEin Bereich der supramolekularen Chemie umfasst die Synthese diskreter dreidimensionaler Aggregate durch Koordination von Übergangsmetallen. Ein Teil dieses Gebiets ist die Chemie der supramolekularen Käfigverbindungen, die durch Knüpfung koordinativer Bindungen entstehen. Heute kennt man ein breites Spektrum solcher supramolekularen Koordinationskäfige. Relativ selten sind jedoch analoge organische Käfigverbindungen, die aus kovalenten Bindungsbildungen resultieren. In letzter Zeit wurden auf diesem Gebiet einige wichtige Fortschritte erzielt, nicht zuletzt durch Anwendung neuer Konzepte wie der dynamischen kovalenten Chemie. Diese Konzepte machen es möglich, organische Käfigverbindungen in wenigen Stufen und guten Ausbeuten zu synthetisieren, und das meist aus einfach zugänglichen Ausgangsverbindungen.
Erratum: A novel catalyst for the glycolysis of poly(ethylene terephthalate) K. Troev, G. Grancharov, R. Tsevi, I. Gitsov. Journal of Applied Polymer Science, 2003; 90: 1148–1152
Authors: Troev K. , Grancharov G. , Tsevi R. , Gitsov I. 
Published: June 2010

AbstractThe original article to which this Erratum refers was published in Journal of Applied Polymer Science, 90, (4) 2003, 1148–1152.No abstract.
New polyol for production of rigid polyurethane‐polyisocyanurate foams, Part 2: Preparation of rigid polyurethane‐polyisocyanurate foams with the new polyol
Authors: Paciorek‐Sadowska Joanna , Czupryński Bogusław , Liszkowska Joanna 
Published: June 2010

AbstractThe method of preparation, determination of foaming parameters, and methods for the determination of physicochemical properties of polyurethane‐polyisocyanurate (PUR‐PIR) foams prepared with the use of N,N′‐di(methyleneoxy‐2‐hydroxyethyl)urea and boric acid derivatives are presented in this paper. It was found that application of the borate as a polyol component and simultaneously as a flame retardant in the recipe for production of PUR‐PIR foams was very favorable. The foams prepared were characterized by reduced brittleness, higher compressive strength and content of closed cells, as well as considerably lower flammability in comparison with standard foam. The results show that the new polyol prepared on the basis of N,N′‐di(methyleneoxy‐2‐hydroxyethyl)urea and boric acid can be applied for production of rigid PUR‐PIR foams, and it improves their physicochemical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Dry‐jet‐wet spun polyurethane fibers. I. Optimization of the spinning parameters
Authors: Reddy G. V. Raghunath , Deopura B. L. , Joshi Mangala 
Published: June 2010

AbstractThis study examined the spinning of polyurethane‐based elastomeric fibers with the dry‐jet‐wet spinning method. The three important spinning variables that were chosen were the coagulation bath ratio (dimethylformamide/water), the bath temperature, and the stretch ratio. A three‐variable factorial design method, proposed by Box and Behnken, was used to optimize these process parameters. The spinning process was further fine‐tuned by the variation of the stretch ratio and the dope solid content. The effect of the dry‐jet length on the fiber properties was also studied. The tenacity and elastic recovery properties of the fibers were found to be optimum at a bath ratio (dimethylformamide/water) of 60 : 40, a bath temperature of 15°C, and a stretch ratio of 2.5. The density and sonic modulus were measured to determine the effect of varying the process variables on structural parameters such as the density and orientation. The surface morphological features, as revealed by scanning electron microscopy, were correlated to the fiber properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of positively charged nanofiltration membrane from 2‐hydroxypropyltrimethyl ammonium chloride chitosan by 1,4‐butanediyl diglycidyl ether cross‐linking
Authors: Huang Ruihua , Chen Guohua , Yang Bingchao , Gao Congjie 
Published: June 2010

AbstractA novel positively charged composite nanofiltration (NF) membrane was prepared using 2‐hydroxypropyltrimethyl ammonium chloride chitosan as active layer, polyacrylonitrile ultrafiltration membrane as substrate layer, and 1,4‐butanediol diglycidyl ether as cross‐linking reagent. The observation from scanning electron microscope revealed its composite structure. At room temperature and cross‐flow rate of 40 L h−1, the permeability for pure water was 14.3 L h−1 m−2 MPa−1. With an increase in operating pressure, the flux increased linearly. The rejection to different salt solutions was decreasing in the order of CaCl2, MgCl2, MgSO4, NaCl, and Na2SO4, revealing the rejection characteristic of positively charge NF membrane. And it had good ion perm‐selectivity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Enhancement of glutaryl‐7‐aminocephalosporanic acid acylase activity of γ‐glutamyltranspeptidase of Bacillus subtilis
Authors: Suzuki Hideyuki , Yamada Chiaki , Kijima Kyoko , Ishihara Sayaka , Wada Kei , Fukuyama Keiichi , Kumagai Hidehiko 
Published: June 2010

AbstractSemisynthetic cephalosporins, the best‐selling antibiotics worldwide, are derived from 7‐aminocephalosporanic acid (7‐ACA). Currently, in the pharmaceutical industrie, 7‐ACA is mainly produced from cephalosporin C by sequential application of D‐amino acid oxidase and cephalosporin acylase. Here we study the potential of industrially amenable enzyme γ‐glutamyltranspeptidase from Bacillus subtilis for 7‐ACA production, since the wild‐type γ‐glutamyltranspeptidase of B. subtilis has inherent glutaryl‐7‐aminocephalosporanic acid acylase activity with a kcat value of 0.0485 s‐1. Its activity has been enhanced by site directed and random mutagenesis. The kcat/Km value was increased to 3.41 s‐1 mM‐1 for a E423Y/E442Q/D445N mutant enzyme and the kcat value was increased to 0.508 s‐1 for a D445G mutant enzyme. Consequently, the catalytic efficiency and the turnover rate were improved up to about 1000‐fold and 10‐fold, compared with the wildtype γ‐glutamyltranspeptidase of B. subtilis.
Die Geschichte der Kolibakterien. Vom Darmbewohner zum Bioreaktor
Authors: Steverding Dietmar 
Published: June 2010

AbstractDas von Theodor Escherich vor 125 Jahren entdeckte E. coli‐Bakterium hat wie kein anderes die Entwicklung der molekularbiologischen Forschung und der medizinischen und industriellen Biotechnologie beeinflusst. Vor allem die Eigenschaften des K12‐Stammes im Hinblick auf Apathogenität, Kultivierbarkeit und Transformierbarkeit haben E. coli zum “Haustier” der Genetiker und Molekularbiologen gemacht. Die Leichtigkeit, mit der gentechnisch veränderte E. coli hergestellt werden können, ließen dieses Bakterium zum beliebten Produktionsorganismus in der modernen Biotechnologie zur Erzeugung von Medikamenten und Feinchemikalien werden. Als physiologischer Darmbewohner von Menschen und Tieren wird E. coli als Indikatororganismus für fäkale Verunreinigungen von Grund‐ und Trinkwasser verwendet. Neben seiner mikroökologischen Rolle im Magen‐Darm‐Trakt kommt ihm in Form von pathogenen Stämmen auch eine Bedeutung als Erreger von Durchfallerkrankungen zu.
Western‐Blot Teil 2: Die Immunreaktion
Authors: Schrödel Andrea 
Published: June 2010

AbstractMit einer Nachweisgrenze von 10–100 Femtomol ist der Western Blot ist eine sehr sensitive Methode, um bestimmte Proteine in einem Proteingemisch mit Hilfe spezifischer Antikörper zu identifizieren.
Maleimide‐Modified Phosphonium Ionic Liquids: A Template Towards (Multi)Task‐Specific Ionic Liquids
Authors: Tindale Jocelyn J. , Hartlen Kurtis D. , Alizadeh Abdolhamid , Workentin Mark S. , Ragogna Paul J. 
Published: June 2010

AbstractThe synthesis and characterization of several compounds representing a new class of multitask‐specific phosphonium ionic liquids that contain a maleimide functionality is reported. The maleimide moiety of the ionic liquid (IL) is shown to undergo Michael‐type additions with substrates containing either a thiol or amine moiety, thus, serving as a template to introduce wide structural diversity into the IL. Multitask‐specific ILs are accessible by reaction of the maleimide with Michael donors that are capable of serving some function. As a model example to illustrate this concept, a redox active ferrocenyl thiol was incorporated and examined by cyclic voltammetry. Because the maleimide moiety is highly reactive to additions, the task‐specific ionic liquids (TSILs) are prepared as the furan‐protected Diels–Alder maleimide. The maleimide moiety can then be liberated when required by simple heating.
Switchable Cucurbituril–Bipyridine Beacons
Authors: Sinha Mantosh K. , Reany Ofer , Parvari Galit , Karmakar Ananta , Keinan Ehud 
Published: June 2010

Abstract4‐Aminobipyridine derivatives form strong inclusion complexes with cucurbit[6]uril, exhibiting remarkably large enhancements in fluorescence intensity and quantum yields. The remarkable complexation‐induced pKa shift (ΔpKa=3.3) highlights the strong charge–dipole interaction upon binding. The reversible binding phenomenon can be used for the design of switchable beacons that can be incorporated into cascades of binding networks. This concept is demonstrated herein by three different applications: 1) a switchable fluorescent beacon for chemical sensing of transition metals and other ligands; 2) direct measurement of binding constants between cucurbit[6]uril and various nonfluorescent guest molecules; and 3) quantitative monitoring of biocatalytic reactions and determination of their kinetic parameters. The latter application is illustrated by the hydrolysis of an amide catalyzed by penicillin G acylase and by the elimination reaction of a β‐cabamoyloxy ketone catalyzed by aldolase antibody 38C2.
[4+2] Cycloaddition Reactions Between 1,8‐Disubstituted Cyclooctatetraenes and Diazo Dienophiles: Stereoelectronic Effects, Anticancer Properties and Application to the Synthesis of 7,8‐Substituted Bicyclo[4.2.0]octa‐2,4‐dienes
Authors: Grange Rebecca L. , Gallen Michael J. , Schill Heiko , Johns Jenny P. , Dong Lin , Parsons Peter G. , Reddell Paul W. , Gordon Victoria A. , Bernhardt Paul V. , Williams Craig M. 
Published: June 2010

AbstractA detailed examination of [4+2] cycloaddition reactions between 1,8‐disubstituted cyclooctatetraenes and diazo compounds revealed that 4‐phenyl‐1,2,4‐triazole‐3,5‐dione (PTAD) reacts to form either 2,3‐ or 3,4‐disubstituted adducts. The product distribution can be controlled by modulating the electron density of the cyclooctatetraene. Unprecedented [4+2] cycloadditions between diisopropyl azodicarboxylate (DIAD) and 1,8‐disubstituted cyclooctatetraenes are also described and further manipulation of a resulting cycloadduct uncovered a new pathway to the synthetically challenging bicyclo[4.2.0]octa‐2,4‐diene family. Variation of the substituents resulted in a range of compounds displaying selective action against different human tumour cell types.
Sonochemical Preparation of Hierarchical ZnO Hollow Spheres for Efficient Dye‐Sensitized Solar Cells
Authors: He Chun‐Xiu , Lei Bing‐Xin , Wang Yu‐Fen , Su Cheng‐Yong , Fang Yue‐Ping , Kuang Dai‐Bin 
Published: June 2010

AbstractHierarchical ZnO hollow spheres (400–500 nm in diameter) consisting of ZnO nanoparticles with a diameter of approximately 15 nm have been successfully prepared by a facile and rapid sonochemical process. The formation of hierarchical ZnO hollow spheres is attributed to the oriented attachment and subsequent Ostwald ripening process according to time‐dependent experiments. The as‐prepared ZnO hollow spheres are used as a photoanode in dye‐sensitized solar cells and exhibit a highly efficient power conversion efficiency of 4.33 %, with a short‐circuit current density of 9.56 mA cm−2, an open‐circuit voltage of 730 mV, and a fill factor of 0.62 under AM 1.5 G one sun (100 mW cm−2) illumination. Moreover, the photovoltaic performance (4.33 %) using the hierarchical ZnO hollow spheres is 38.8 % better than that of a ZnO nanoparticle photoelectrode (3.12 %), which is mainly attributed to the efficient light scattering for the former.