bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fight against new types of influenza virus
Authors: Romanova Julia 
Published: November 2006

AbstractIn 1997, during an outbreak in chickens in Hong Kong the avian H5N1 influenza virus crossed the species barrier and infected 18 people, of which 6 cases were fatal. The virus also infected wild birds and continued to circulate and mutate in geese and ducks in southeastern China. Since this occurrence, new antigenic variants that are highly pathogenic for humans as well as wild, domestic, and exotic waterfowl continue to appear in Hong Kong. This virus is spreading across Asia, and is encroaching upon Europe and other continents. Wild birds are now considered as the main reservoir of H5N1 virus. Humans become infected with this H5N1 virus usually via close contact with infected birds or a highly contaminated environment. The very low transmissibility of this virus prevented further person‐to‐person dissemination in spite of the complete absence of immunity in the human population to H5N1 viruses. Viruses of the H5N1 subtype are characterized by an exceptionally high pathogenicity for humans. The cause of the viral virulence is not known so far; however, several virulence factors are considered. The unprecedented capability of H5N1 viruses to kill humans intensifies the concern about its pandemic potential with catastrophic consequences. The effectiveness of existing antivirals as well as vaccines for humans and birds are reviewed.
Reactions of Hydrogen Atoms with Met‐Enkephalin and Related Peptides
Authors: Mozziconacci Olivier , Bobrowski Krzysztof , Ferreri Carla , Chatgilialoglu Chryssostomos 
Published: November 2006

AbstractThe reactions of hydrogen atoms with enkephalins and related peptides have been investigated by radiolytic methods in aqueous solutions and lipid vesicle suspensions. Pulse radiolysis experiments indicate that methionine residue (Met) is the main target. In Met‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Met) the attack of the hydrogen atom occurs to about 50 % on Met with formation of methanethiyl radical. The remaining percentage is divided roughly evenly between Tyr and Phe. With Leu‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Leu) the site of attack is limited to Tyr and Phe. Using a peptide–liposome (that is, 1‐palmitoyl‐2‐oleoyl phosphatidylcholine vesicles) model, the cis–trans isomerization of phospholipids could be detected due to the catalytic action of thiyl radicals. The radiation chemical yields of the H. and, consequently of CH3S. radical, was modulated by the experimental conditions and the nature of peptide. Large amounts of trans lipids observed in phosphate buffer vesicle suspensions indicated the efficient role of double‐bond isomerization as marker of Met‐containing peptide damage.
Nanocomposite and Nanoporous Polyaniline Conducting Polymers Exhibit Enhanced Catalysis of Nitrite Reduction
Authors: Luo Xiliang , Killard Anthony J. , Smyth Malcolm R. 
Published: November 2006

AbstractNanostructured polyaniline (PANI) conducting polymer films were prepared on electrochemically pretreated glassy carbon electrodes, which were previously modified with multilayers of polystyrene (PS) nanoparticles with a diameter of 100 nm. PANI was electropolymerised and grown through the interstitial spaces between the PS nanoparticles, which formed a nanocomposite film of PANI and PS nanoparticles on the electrode surface. Furthermore, a nanoporous PANI film was fabricated through the removal of the PS nanoparticles by dissolution in toluene. As a result of their nanostructure, both of the PANI films (before and after removal of the PS nanoparticles) exhibited enhanced electrocatalytic behaviour towards the reduction of nitrite relative to bulk‐PANI films; however, partial collapse or shrinkage may have occurred with the removal of the nanoparticles and could have resulted in a less enhanced response. Under optimised conditions, the nanocomposite‐film‐modified electrode exhibited a fast response time of 5 s and a linear range from 5.0×10−7 to 1.4×10−3 M for the detection of nitrite; the detection limit was 2.4×10−7 M at a signal‐to‐noise ratio of 3.
Total Synthesis and Evaluation of the Actin‐Binding Properties of Microcarpalide and a Focused Library of Analogues
Authors: Fürstner Alois , Nagano Takashi , Müller Christoph , Seidel Günter , Müller Oliver 
Published: November 2006

AbstractA comparative investigation shows that hydroxylated 10‐membered lactones modeled around the fungal metabolites microcarpalide (1) and pinolidoxin (2) are endowed with selective actin‐binding properties. Although less potent than the marine natural product latrunculin A, which represents the standard in the field, nonenolides of this type are significantly less toxic and accommodate substantial structural editing. Most notable is the fact that even an intramolecular transesterification with formation of a hydroxylated butanolide skeleton does not annihilate their microfilament disrupting capacity. This finding calls for a reinvestigation of the biological profile of other fungal metabolites that embody a similar motif. Microcarpalide (1) serving as the calibration point for this comparative study was prepared by total synthesis based on ring‐closing metathesis (RCM) as the key step. The chosen route favorably compares to previous approaches to this target and provides further support for the notion that the (E,Z)‐configuration of a medium‐sized cycloalkene can be controlled by proper choice of the catalyst as previously outlined by our group. 9‐epi‐Microcarpalide26and furanone27as representative examples of the “natural productlike” compounds investigated herein have been characterized by crystal structure analysis.
Heat‐shock protein peptide DiaPep277 treatment in children with newly diagnosed type 1 diabetes: a randomised, double‐blind phase II study
Authors: Lazar L. , Ofan R. , Weintrob N. , Avron A. , Tamir M. , Elias D. , Phillip M. , Josefsberg Z. 
Published: November 2006

AbstractBackgroundType 1 diabetes mellitus (T1DM) is a T‐cell‐mediated autoimmune disease that leads to the destruction of insulin‐producing beta cells. Treatment with DiaPep277, a peptide derived from heat‐shock protein 60 (hsp60), has been found to slow the deterioration of beta‐cell function after clinical onset of diabetes in NOD mice and human adults. Our aim was to evaluate the efficacy and safety of DiaPep277 treatment in attenuating beta‐cell destruction in children with recent‐onset T1DM.MethodsA prospective, randomized, double‐blind, phase II design was used. The sample included 30 children (19 males) aged 7–14 years who had been diagnosed with T1DM from 53 to 116 days previously, and had basal C‐peptide concentrations above 0.1 nmol/L. The children were randomized to receive subcutaneous injections of 1 mg DiaPep277 (15 patients) or 40 mg mannitol (placebo) at entry and at 1, 6, and 12 months. The duration of follow‐up was 18 months. The groups were compared for stimulated C‐peptide level, exogenous insulin dose, and HbA1c concentration.ResultsC‐peptide levels similarly decreased over time in the DiaPep277‐ and placebo‐treated patients. There was no significant difference in insulin dose or HbA1c concentration between the groups at any time point. No serious drug‐related adverse effects were recorded throughout the study period.ConclusionsOne‐year treatment with DiaPep277 at a dosage of 1 mg is safe for use and well tolerated in children with recent‐onset T1DM. However, it appears to have no beneficial effect in preserving beta‐cell function or improving metabolic control. Copyright © 2007 John Wiley & Sons, Ltd.
Preconcentration and Determination of a Phospholipid at a Surface Modified by Layer‐by‐Layer Assembly
Authors: Wandstrat M. M. , Cox J. A. 
Published: November 2006

AbstractElectrochemical oxidation of a phospholipid, phosphatidylcholine (PC), was accomplished at a 4‐aminothiophenol (ATP)‐modified gold electrode coated with a layer‐by‐layer assembly of an electrochemical catalyst (dirhodium phosphomolybdic acid), a trapping agent for PC (a cyclophane, CP, derivative, 1,4‐xylylene‐1,4‐phenylene‐diacetate), and a spacer (generation‐4 polyamidoamine dendrimer, PAMAM). The layer‐by‐layer assembly process and the trapping of PC was verified by quartz crystal microbalance measurements; Au|ATP|CP|PAMAM|CP trapped (1.5±0.4)×10−9 mol cm−2 of PC. The electrocatalytic oxidation of PC yielded a current that varied linearly with concentration over the range 1–50 μM; the R2 value was 0.996.
Redox Spectra Of Wines
Authors: Ksenzhek Octavian , Petrova Svetlana , Kolodyazhny Michael 
Published: November 2006

AbstractThe method of thin layer voltammetry on pyrolytic graphite electrodes was applied for analysis of Crimean wines on the content of electrochemically active components. The cyclic voltammetric curves were resolved into a set of peaks corresponding to the electrochemical conversion of quinones and phenolics. The final results of such analysis are represented as diagrams, which we call the “Redox Spectra of Wines”. The Redox Spectra of Wines were found to be their specific characteristics. The method may be regarded as promising for the evaluation of authenticity of wines.
A Porous ITO Nanoparticles Modified Electrode for the Redox Liquid Immobilization
Authors: Niedziolka Joanna , Szot Katarzyna , Marken Frank , Opallo Marcin 
Published: November 2006

AbstractTin‐doped indium oxide (ITO) nanoparticles (ca. 20 nm in diameter) were deposited onto electrode surfaces employing a simple immersion, withdrawal and solvent evaporation method. The resulting ITO films are irregularly packed and highly porous and they promote electron transport. When water insoluble redox liquids are immobilized within the porous film efficient electrochemical reactions occur at the solid‐liquid and at liquid‐liquid interfaces. Scanning electron microscopy reveals a macroscopically uniform surface of the deposit. The thickness of the film estimated by atomic force microscopy is proportional to the number of deposited layers with a thickness increase per single immersion and withdrawal step equal to approximately 60 nm. However, the films are deposited non‐uniformly and the thickness only provides an average parameter. The results of voltammetric experiments performed in aqueous electrolyte solution indicate good adhesion and wetting of the deposit. The surface electroactivity towards the electrooxidation of ferrocenedimethanol provides highly reversible responses without any blocking effects. The ITO nanoparticle modified electrode surface was impregnated with nanomole amounts of a hydrophobic redox liquid, tert‐butylferrocene, and then immersed in the aqueous electrolyte solutions. The value of the voltammetric peak current and the efficiency of the multi‐phase electrode process improved proportional to the number of immersion and withdrawal steps from ITO nanoparticles suspension. This improvement is also observed after further electrode modification with a hydrophobic thin film via sol‐gel processing of methyltrimethoxysilane. In this case the porous film at the electrode surface can be surface modified to provide affinity to certain liquids or analytes.
Investigation of Graphite Electrodes Modified with Cellobiose Dehydrogenase from the Ascomycete Myriococcum thermophilum
Authors: Harreither Wolfgang , Coman Vasile , Ludwig Roland , Haltrich Dietmar , Gorton Lo 
Published: November 2006

AbstractThe catalytic properties of cellobiose dehydrogenase (CDH) from the ascomycete fungus Myriococcum thermophilum adsorbed on a graphite electrode were investigated for a large variety of carbohydrate substrates. The effects of applied potential, pH and buffer composition were tested and optimized, and the most suitable conditions were used to evaluate the detection limit, linear range, and sensitivity of the sensor for different carbohydrates in the flow injection mode. Subsequently, the long term stability of the modified electrodes was determined. Additionally, the direct and mediated electron transfer between the active site of the enzyme and the electrode has been investigated by amperometric flow injection measurements in the absence and presence of the mediator 1,4‐benzoquinone in the presence of cellobiose or lactose.
Towards a portable microchip system with integrated thermal control and polymer waveguides for real‐time PCR
Authors: Wang Zhenyu , Sekulovic Andrea , Kutter Jörg P. , Bang Dang D. , Wolff Anders 
Published: November 2006

AbstractA novel real‐time PCR microchip platform with integrated thermal system and polymer waveguides has been developed. The integrated polymer optical system for real‐time monitoring of PCR was fabricated in the same SU‐8 layer as the PCR chamber, without additional masking steps. Two suitable DNA binding dyes, SYTOX Orange and TO‐PRO‐3, were selected and tested for the real‐time PCR processes. As a model, cadF gene of Campylobacter jejuni has been amplified on the microchip. Using the integrated optical system of the real‐time PCR microchip, the measured cycle threshold values of the real‐time PCR performed with a dilution series of C. jejuni DNA template (2 to 200 pg/µL) could be quantitatively detected and compared with a conventional post‐PCR analysis (DNA gel electrophoresis). The presented approach provided reliable real‐time quantitative information of the PCR amplification of the targeted gene. With the integrated optical system, the reaction dynamics at any location inside the micro reaction chamber can easily be monitored.
TK/TD dose–response modeling of toxicity
Authors: Begum Munni , Sen Pranab K. 
Published: November 2006

AbstractIn environmental cancer risk assessment of a toxic chemical, the main focus is in understanding induced target organ toxicity that may in turn lead to carcinogenicity. Mathematical models based on systems of ordinary differential equations with biologically relevant parameters are tenable methods for describing the disposition of chemicals in target organs. In evaluation of a toxic chemical, dose–response assessment often addresses only toxicodynamics (TD) of the chemical, while its toxicokinetics (TK) do not enter into consideration. The primary objective of this research is to integrate both TK and TD in evaluation of toxic chemicals while performing dose–response assessment. Population models, with hierarchical setup and nonlinear predictors, for TK concentration and TD effect measures are considered. A one‐compartment model with biologically relevant parameters, such as organ volume, uptake rate and excretion rate, or clearance, is used to derive the TK predictor while a two parameter Emax model is used as a predictor for TD measures. Inference of the model parameters with nonnegative and assay's Limit of Detection (LOD) constraints was carried out by Bayesian approaches using Markov Chain Monte Carlo (MCMC) techniques. Copyright © 2006 John Wiley & Sons, Ltd.
Inhibition of Flt3‐activating mutations does not prevent constitutive activation of ERK/Akt/STAT pathways in some AML cells: a possible cause for the limited effectiveness of monotherapy with small‐molecule inhibitors
Authors: Siendones Emilio , Barbarroja Nuria , Torres Luis Arístides , Buendía Paula , Velasco Francisco , Dorado Gabriel , Torres Antonio , López‐Pedrera Chary 
Published: November 2006

AbstractThe Flt3 receptor tyrosine kinase is a critical mediator in the pathogenesis of acute myeloid leukaemia (AML). Flt3‐activating mutations have been associated with poor prognosis and decreased overall survival of AML patients, thus Flt3 constitutes an ideal target for drug treatment of such disease. Unfortunately, the monotherapy with small‐molecule tyrosine kinase inhibitors in clinical trials shows that remission is not permanent, presumably by resistance of Flt3 mutants to inhibitors. An alternative approach for treatment is based on the cooperation between Flt3 and additional intracellular pathways for AML transformation in some patients. Thus, the inhibition of both Flt3 and such pathways may be exploited for successful treatment of the disease. We investigated the importance of Flt3‐activating mutations for the constitutive activation of intracellular pathways in primary AML cells, and their effect on cell survival. We found that the main compounds involved in the differentiation, proliferation and survival of AML (MAPK/AKT/STAT) were constitutively activated. However, only four samples showed internal tandem duplications (ITDs) for Flt3. Surprisingly, contrary to previous reports, we found that inhibition of ITD/Flt3 activity did not prevent the phosphorylation of ERK, STAT5 or Akt in some primary AML cells. In parallel, we found that in these cells, Flt3 and ERK or Akt cooperate to regulate cell survival. Our results support the hypothesis that the optimal therapeutic treatment of AML may require not only the oncogenic tyrosine kinase, but also the appropriate combination of different specific inhibitors, thus providing a more effective approach to reverse leukaemogenesis. Thus, we propose that each AML patient should have an individually tailored combination treatment. Copyright © 2006 John Wiley & Sons, Ltd.
Minimizing the surface effect of PDMS–glass microchip on polymerase chain reaction by dynamic polymer passivation
Authors: Xia Yong‐Mei , Hua Zhi‐Shan , Srivannavit Onnop , Ozel Ayse Bilge , Gulari Erdogan 
Published: November 2006

AbstractPolydimethyl siloxane (PDMS)–glass microchip has a very strong surface effect on polymerase chain reaction (PCR), leading to a very poor PCR yield. In the work reported here, practical dynamic passivation of surfaces of PDMS–glass microchip using polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP) was achieved using a conventional thermocycler. The passivation procedure was cost‐effective and easy to conduct. The effects of polymer molecular weight and polymer concentration on tube PCR efficiency were investigated primarily to prescreen out suitable polymers and polymer concentrations in the PCR mixture. The result from tube PCR indicated that both PEG and PVP could affect the performance of Taq polymerase. A final concentration of 0.025% (w/v) or 0.4% (w/v) polymer in the PCR mixture can enhance the tube PCR, while 1% (w/v) polymer was found to inhibit the reaction. PEG was more effective in tube PCR, although PVP performed better in chip PCR. Instead of employing the polymer directly in the PCR mixture, i.e. the conventional in situ passivation approach, another approach of dynamic passivation by pre‐injecting polymers into the microchip achieved better performance. The efficiency of pre‐passivation was found to follow the order: PVP10000>PVP55000, PEG8000> PEG10000>PEG400. After pre‐passivation with PVP10000, PVP55000 and PEG8000, the PCR efficiency can recover to 93%, 86% and 83%, respectively, of that obtained from tube PCR. Copyright © 2006 Society of Chemical Industry
Team effectiveness under stress: a structural contingency approach
Authors: Drach‐Zahavy Anat , Freund Anat 
Published: November 2006

AbstractTo examine whether working under stressful circumstances restricts or enhances team effectiveness, a structural contingency model for team effectiveness was tested by focusing on job structuring (mechanistic/organic structuring) as a key factor, which interacts with qualitative and quantitative stress on team attitude (team commitment) and outcomes (team effectiveness). Findings from 73 primary care teams indicated that mechanistic structuring for teams working under quantitative stress was positively associated with team commitment, which in turn fostered team effectiveness, whereas organic structuring for working under qualitative stress improved team effectiveness. Furthermore, team commitment mediated the relationships between stress and structuring and team effectiveness. These findings support a structural contingency model for improving team effectiveness under stress. Copyright © 2006 John Wiley & Sons, Ltd.
Raman study of methane clathrate hydrates under pressure: new evidence for the metastability of structure II
Authors: Choukroun Mathieu , Morizet Yann , Grasset Olivier 
Published: November 2006

AbstractNew high‐pressure experiments on the H2OCH4 system have been conducted for investigating the structure of methane hydrates (MH) under pressure. Interestingly, structure II (sII) MH was generated and locally coexisted with structure I (sI) up to 500 MPa. The Raman analysis of MH formation during the experiments allowed us to distinguish two possible evolutions: (1) a direct crystallization of sI MH from CH4 gas and (2) an indirect evolution from gas to sII, followed by a sII–sI transition. Calculations show that H2O molar fraction is 2.9–25% lower in sII MH than in sI in the early stages of hydrate formation. We suggest that sII MH crystallize locally because the amounts of H2O available for sI MH generation are too low.A first synthesis of the MH Raman signature under pressure is also provided. In addition to the description of well‐known signatures of MH, a new Raman band assigned to a ν3 asymmetric stretching mode of CH bonds in CH4 is observed in sI MH at 3055 cm−1 and at 3060 cm−1 in the high‐pressure phase MH II. The first scaling law describing the evolution with pressure of the CH bonds' ν1 peak position within small cages is established. Also, OH and OO bonds' signatures and evolution with pressure are almost identical in MH and ice Ih up to 1 GPa. Such a pressure range is much wider than the stability domain of ice Ih. This result magnifies the role of guest–host interactions in the stabilization of the hydrate structure. Copyright © 2006 John Wiley & Sons, Ltd.
PEG‐PLA Block Copolymer as Potential Drug Carrier: Preparation and Characterization
Authors: Ben‐Shabat Shimon , Kumar Neeraj , Domb Abraham J. 
Published: November 2006

AbstractSummary: Diblock and multiblock copolymers composed of a poly(D,L‐lactide) (PLA) or poly(trimethylene carbonate) (PTMC) core with a hydrophilic chain of poly(ethylene glycol) (PEG) were prepared. These copolymers, in which the core is connected to PEG through a polyfunctional molecule such as citric, mucic, or tartaric acid, may be used to form nanoparticles for drug delivery applications. Branched copolymers were prepared by direct amidation between the polyfunctional acid and methoxy PEGamine, followed by ring‐opening polymerization of lactide or trimethyl carbonate to form the PLA and PTMC block copolymers. In addition, a complex multiblock copolymer of biotin‐PEG‐poly[lactic‐co‐(glycolic acid)] (PLGA) for application in an avidin‐biotin system was prepared for possible design of nanospheres with targeting properties. Studies of drug release from polymeric systems containing multiblock copolymers and studies of polymer degradation were also performed.
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Amphiphilic Poly(N‐propargylamide) with Galactose and Lauryloyl Groups: Synthesis and Properties
Authors: Suenaga Masakazu , Kaneko Yoshiro , Kadokawa Jun‐ichi , Nishikawa Takehiro , Mori Hidezo , Tabata Masayoshi 
Published: November 2006

AbstractSummary: An amphiphilic poly(N‐propargylamide) with galactose and lauryloyl groups was synthesized by copolymerization of the corresponding N‐propargylamide monomers using a Rh catalyst. The obtained copolymer formed a one‐handed helical conformation and molecular aggregates in water. The observations by fluorescence microscopy in a cell culture experiment in the presence of dye‐labeled copolymer indicated that the copolymer was incorporated into the cells.Localization of rhodamine B‐labeled copolymer 8 in human aortic endothelial cells (fluorescence image).magnified imageLocalization of rhodamine B‐labeled copolymer 8 in human aortic endothelial cells (fluorescence image).