bluuebunny/crossref_metadata_2025_split huggingface dataset:
17β‐Estradiol attenuates hyperoxia‐induced apoptosis in mouse C8‐D1A cell line
Authors: Huppmann Stephanie , Römer Susanne , Altmann Rodica , Obladen Michael , Berns Monika 
Published: July 2008

AbstractIn premature infants, oxygen free radicals generated following neonatal resuscitation are associated with subsequent diseases such as retinopathy of prematurity and bronchopulmonary dysplasia. Recent studies in brain tissue samples have shown that nonphysiologic oxygen levels play a key role in induction of apoptosis in the developing brain. Estrogen is a well‐established agent in neuroprotection and, therefore, is thought to be neuroprotective even in the premature brain. Astrocytes appear to have a critical role in protection and survival of neurons in the brain. As one of the glial cell types, they have a great potential for possible involvement in the mediation of estrogen neuroprotective effects. The aim of our study was to analyze whether astrocytes in cell cultures are damaged by hyperoxia and whether 17β‐estradiol (E2) can protect them against apoptosis. Additionally, we investigated the mechanism of the protection by E2, hypothesizing that it is mediated through extracellular signal‐regulated kinase (ERK1/2). Cells underwent eightfold more apoptosis when cultivated in hyperoxia compared with normoxia. Addition of E2 reduced apoptosis in hyperoxia by more than 50%. Levels of ERK1/2 and phosphorylated ERK1/2 were increased after hyperoxia compared with normoxia. Preincubation with E2 prior to exposure to hyperoxia resulted in decreased levels of ERK1/2 and pERK1/2. Hyperoxia induces apoptosis in C8‐D1A cells, and E2 seems to be a protecting factor for astrocytes in hyperoxia. This effect is not mediated through up‐regulation of pERK1/2. © 2008 Wiley‐Liss, Inc.
Liquid‐phase microextraction for rapid AP‐MALDI and quantitation of nortriptyline in biological matrices
Authors: Wu Hui‐Fen , Ku Hsin‐Yi , Yen Jyh‐Hao 
Published: July 2008

AbstractA liquid‐phase microextraction (LPME) method using a micropipette with disposable tips was demonstrated for coupling to atmospheric pressure MALDI‐MS (AP‐MALDI/MS) as a concentrating probe for rapid analysis and quantitative determination of nortriptyline drug from biological matrices including human urine and human plasma. This technique was named as micropipette extraction (MPE). The best optimized parameters of MPE coupled to AP‐MALDI/MS experiments were extraction solvent, toluene; extraction time, 5 min; sample agitation rate, 480 rpm; sample pH, 7; salt concentration, 30%; hole size of micropipette tips, 0.61 mm (id); and matrix concentration, 1000 ppm using α‐cyano‐4‐hydroxycinnamic acid (CHCA) as a matrix. Three detection modes of AP‐MALDI/MS analysis including full scan, selective ion monitor (SIM), and selective reaction monitor (SRM) of MS/MS were also compared for the MPE performance. The results clearly demonstrated that the MS/MS method provides a wider linear range and lower LODs but poor RSDs than the full scan and SIM methods. The LOD values for the MPE under SIM and MS/MS modes in water, urine, and plasma were 6.26, 47.5, and 94.9 nM, respectively. The enrichment factors (EFs) of this current approach were 36.5–43.0 fold in water. In addition, compared to single drop microextraction (SDME) and LPME using a dual gauge microsyringe with a hollow fiber (LPME‐HF) technique, the LODs acquired by the MPE method under MS/MS modes were comparable to those of LPME‐HF and SDME but it is more convenient than both methods. The advantages of this novel method are simple, easy to use, low cost, and no contamination between experiments since disposable tips were used for the micropipettes. The MPE has the potential to be widely used in the future because it only requires a simple micropipette to perform all extraction processes. We believe that this technique can be a powerful tool for MALDI/MS analysis of biological samples and clinical applications.
Molecularly imprinted polymers for bisphenol A for HPLC and SPE from water and milk
Authors: Alexiadou Despina K. , Maragou Niki C. , Thomaidis Nikolaos S. , Theodoridis Georgios A. , Koupparis Michael A. 
Published: July 2008

AbstractMolecularly imprinted polymers (MIPs) for bisphenol A (BPA) were prepared by two synthetic routes: semi‐covalent and noncovalent methodology. The molecular imprinting effect was evaluated using the polymers in HPLC and SPE. Polymers prepared with noncovalent mode were proven more effective. These polymers were applied in SPE facilitating selective retention of BPA from bottled water and milk. The developed sample preparation was simple and efficient comprising only dilution of milk and MISPE prior to LC‐MS analysis. Overall MISPE enhanced sample clean‐up. Compared with control nonimprinted polymers and conventional C18 SPE cartridges, the MIPs exhibited selective analyte recognition. The method provided quantitative BPA recoveries, very good reproducibility (% RSDs lower than 7%), and low LOD (0.2 ng/g). MIP interacts similarly with deuterated BPA allowing its use as internal standard in LC‐MS. The most critical parameters of MISPE were the organic content in loading–washing medium and the washing volume. Low flow rates in the elution step enhanced extraction recovery. Important advantages of the MIP were: the high breakthrough volumes (> 500 mL of water), high mass capacity (> 10 ng/mg of MIP sorbent), good linearity, and good stability in performance for over 35 cycles of use.
Multi‐residue methods for confirmatory determination of antibiotics in milk
Authors: Samanidou Victoria , Nisyriou Styliani 
Published: July 2008

AbstractThe prevalent use of antibiotics, e. g. sulphonamides, tetracyclines, β‐lactams, macrolides, aminoglycosides, etc., in dairy farming to prevent and treat microbial infections e. g. mastitis, can be a potential source of veterinary drug residues in milk. Antibiotic residues constitute a risk to human health, since they can cause allergic reactions in hypersensitive individuals or they may lead to the appearance of drug‐resistant bacteria. Analysis of these residues plays a key role in ensuring food safety. Regulatory agencies in the European Union and in other countries have established maximum residue limits and requirements concerning the performance of analytical methods and the interpretation of the results. This review describes the state of the art in the analytical strategies concerning the multi‐class as well as the multi‐residue analysis of antibiotics in milk. Since milk is a complex matrix due to its high protein and fat content, which often interfere in analytical procedures, special focus has been placed on sample preparation: extraction and clean‐up. Confirmation of antibiotic residues according to European Decision 657/2002/EC has been also discussed.
Application of the iodine–azide postcolumn reaction in RP‐HPLC for the determination of thioguanine in urine
Authors: Zakrzewski Robert 
Published: July 2008

AbstractThe study focuses on the analysis of a sensitive, selective, and simple postcolumn detection method for thioguanine determination, based on the sensitizing induction of thioguanine on iodine–azide reaction and the combination technique of HPLC. The analysis was accomplished in the optimum conditions for iodine–azide detection system and HPLC separation. The values for the linear range, the LOD, and DOQ amounted to 0.8–1.7, 0.4, and 0.5 nmol/mL urine, respectively.
Analysis of native carotenoid composition in orange juice using C30 columns in tandem
Authors: Dugo Paola , Herrero Miguel , Giuffrida Daniele , Ragonese Carla , Dugo Giacomo , Mondello Luigi 
Published: July 2008

AbstractIn the present contribution, a novel analytical approach based on using serial coupled conventional LC columns is proposed to the study of the native carotenoid composition of orange juice. The great difficulties that are found when analyzing complex carotenoid samples, due to the high natural variability of these compounds as well as to the presence of carotenoid esters are well documented. To overcome some of these limitations, we have developed a methodology including the study of both the saponified and the intact sample by means of two different LC‐DAD/APCI‐MS methods. The increase in the resolution and separation power obtained when using two serial coupled C30 columns is demonstrated, and significant increases in peak capacity have been achieved. By using this new methodology, 44 different carotenoids have been tentatively identified. Among them, several violaxanthin diesters have been directly identified in orange juice for the first time. The main carotenoids in orange juice were violaxanthin, lutein, luteoxanthin, 9‐cis‐antheraxanthin, and β‐cryptoxanthin. Some of them were found in both their free and esterified forms. To the best of our knowledge, this is the first application of serial couplings of C30 columns for the identification of the native carotenoid composition of natural matrices.
Stationary phases for chromatography prepared by ring opening metathesis polymerization
Authors: Buchmeiser Michael R. 
Published: July 2008

AbstractThe chemistry of metathesis polymerization‐derived stationary phases is summarized. Since both ring‐opening metathesis and 1‐alkyne polymerization triggered by well‐defined transition metal alkylidenes are living polymerization methods, they allow for the controlled and highly reproducible synthesis of stationary phases in terms of both the nature and total content of the functional group(s) of interest. In addition, the high functionality tolerance of these polymerization techniques allows for creating chromatographic supports with an unprecedented diversity in terms of functional groups that may be introduced. Their applications in various areas of separation science such as SPE, ion‐chromatography, RP chromatography, chiral chromatography, and the high‐performance liquid chromatographic separation of biomolecules are summarized. Within the context of the latter topic, special attention will be given to metathesis polymerization‐derived monolithic supports. Consideration will also be given to those aspects of polymer chemistry that are relevant to the separation performance of these supports.
Multidimensional liquid phase separations for mass spectrometry
Authors: Tomáš Roman , Klepárník Karel , Foret František 
Published: July 2008

AbstractLarge part of the current research in biology, medicine, and biotechnology depends on the analysis of DNA (genomics), proteins (proteomics), or metabolites (metabolomics). The advances in biotechnology also command development of adequate analytical instrumentation capable to analyze minute amounts of samples. The analysis of the content of single cells may serve as an example of ultimate analytical applications. Most of the separation techniques have been developed in the last three decades and alternative approaches are being investigated. At present, the main protocols for analyses of complex mixtures include 2‐DE (IEF) followed by electrophoresis in SDS polyacrylamide gel (SDS‐PAGE) and chromatographic techniques. Information‐rich techniques such as MS and NMR are essential for the identification and structure analysis of the analyzed compounds. High resolution separation of the individual sample components is often a prerequisite for success. High resolution proteomic analysis in the majority of laboratories still relies on the time consuming and laborious offline methods. This review highlights some of the important aspects of 2‐D separations including microfluidics.
Enantiomeric separation by using nano‐liquid chromatography with on‐column focusing
Authors: D'Orazio Giovanni , Fanali Salvatore 
Published: July 2008

AbstractThe present study shows a new nano‐liquid chromatographic method for β‐blocker enantiomers' separation. This method consists of using a capillary column packed with silica particles which were chemically modified with vancomycin. On‐column focusing allowed to inject relatively high sample volumes (1500 nL) increasing method sensitivity. The studied racemic compounds, namely atenolol, propranolol, oxprenolol, and metoprolol were dissolved in methanol and injected for chromatographic separation. The effect of injected sample volume was studied in the range of 50–2100 nL. Peak height of the two alprenolol enantiomers increased linearly up to 1500 nL. This volume was injected for validation and sample analysis. Under optimal experimental conditions, LODs and LOQs (LOD and LOQ for each alprenolol enantiomers) were 9.0 and 15.6 ng/mL, respectively. Calibration curves were linear in the studied range (9–250 ng/mL). The optimized method was applied to the analysis of a human plasma sample spiked with racemic alprenolol.
A cation‐exchange material for protein separations based on grafting of thiol‐terminated sulfopropyl methacrylate telomers onto hydrophilized monodisperse divinylbenzene particles
Authors: Nordborg Anna , Limé Fredrik , Shchukarev Andrei , Irgum Knut 
Published: July 2008

AbstractA strong cation‐exchange separation material has been prepared from monodisperse divinylbenzene particles modified by a ”grafting to” approach, utilizing as anchoring points epoxy groups introduced onto the surface of the particles via oxidation of residual vinyl groups. The grafted chains consisted of thiol‐terminated telomers of sulfopropyl methacrylate prepared by iniferter mediated polymerization, and grafting was performed by reaction of the corresponding thiolate anion with the surface epoxy groups. Attachment through epoxy moieties that were subsequently converted into 2,3‐propanediol groups increased the hydrophilicity of the polymeric particles and incubation experiments showed no signs of the proteins denaturing on the column during an extended contact time of 1 h at room temperature. The performance of the grafted material was demonstrated by the chromatographic separation of cytochrome C, lysozyme, myoglobin, and ribonuclease A, in a cation‐exchange mode.
Detecting pM concentrations of prostaglandins in cell culture supernatants by capillary SCX‐LC‐MS/MS
Authors: Rinne Dahl Sandra , Ramstad Kleiveland Charlotte , Kassem Moustapha , Lea Tor , Lundanes Elsa , Greibrokk Tyge 
Published: July 2008

AbstractA highly sensitive, improved online strong cation exchange (SCX) – RP capillary liquid chromatographic (cLC) method with IT mass spectrometric (IT‐MS/MS) detection for the simultaneous determination of prostaglandin (PG)A1, PGD2, PGE1, PGE2, PGF2α, 8‐iso‐(8i)PGF2α, 6‐keto‐(6k)PGF1α, and 15‐Δ12, 14‐deoxy‐PGJ2 (15dPGJ2) in cell culture supernatants was developed and validated. Pretreatment of the cell culture supernatants included only dilution and filtration, and the analysis time including all sample preparation steps was 60 min per sample. Peptides/proteins contained in the matrix were removed by the SCX column. LODs in the range of 8–44 pg/mL (25–120 pM) cell culture supernatant were obtained. Excellent linearity (R2 > 0.99) and satisfactory recoveries and within‐ and between‐day precisions were obtained. Human mesenchymal stem cells (hMSCs) were stimulated with tumor necrosis factor α (TNFα) or TNFα/IL‐17, and PG production was analyzed using the developed method. The four PGs, 6kPGF1a, PGF1a, PGE2, and PGE1 were detected both in nonstimulated and stimulated cells. The amount of PG produced by the cell increased when the cell was stimulated.
Methacrylate‐based short monolithic columns: Enabling tools for rapid and efficient analyses of biomolecules and nanoparticles
Authors: Barut Miloš , Podgornik Aleš , Urbas Lidija , Gabor Boštjan , Brne Peter , Vidič Jana , Plevčak Sašo , Štrancar Aleš 
Published: July 2008

AbstractThis review describes the novel chromatography stationary phase – a porous monolithic methacrylate‐based polymer – in terms of the design of the columns and some of the features that make these columns attractive for the purification of large biomolecules. We first start with a brief summary of the characteristics of these large molecules (more precisely large proteins like immunoglobulins G and M, plasmid deoxyribonucleic acid (DNA), and viral particles), and a list of some of the problems that were encountered during the development of efficient purification processes. We then briefly describe the structure of the methacrylate‐based monolith and emphasize the features which make them more than suitable for dealing with large entities. The highly efficient structure on a small scale can be transferred to a large scale without the need of making column modifications, and the various approaches of how this is accomplished are briefly presented in this paper. This is followed by presenting some of the examples from the bioprocess development schemes, where the implementation of the methacrylate‐based monolithic columns has resulted in a very efficient and productive process. Following this, we move back to the analytical scale and demonstrate the efficiency of the monolithic column – where the mass transfer between the stationary and mobile phase is greatly enhanced – for the in‐process and final control of the new therapeutics. The combination of an efficient structure and the appropriate hardware results in separations of proteins with residence time less than 0.1 s.
Capillary electrophoresis of some free fatty acids using partially aqueous electrolyte systems and indirect UV detection. Application to the analysis of oleic and linoleic acids in peanut breeding lines
Authors: Bannore Yogita C. , Chenault Kelly D. , Melouk Hassan A. , El Rassi Ziad 
Published: July 2008

AbstractThis study has shown for the first time the suitability of CE with a partially aqueous electrolyte system for the analysis of free fatty acids (FFAs) in small portions of single peanut seeds. The partially aqueous electrolyte system consisted of 40 mM Tris, 2.5 mM adenosine‐5′‐monophosphate (AMP) and 7 mM α‐CD in (N‐methylformamide) NMF/dioxane/water (5:3:2 by volume) mixture, pH 8–9. While AMP served as the background UV absorber for indirect UV detection of the FFAs, the α‐CD functioned as the selectivity modulator by affecting the relative effective electrophoretic mobilities of the various FFAs due to their differential association with α‐CD. This CE method allowed the screening of peanut seeds for their content of oleic and linoleic acids, which is essential in breeding of peanuts of high‐oleic acid content. The extraction method of FFAs from peanut seeds is very reproducible with a high recovery approaching quantitative yield (∼︁97% recovery).
Structure and performance of silica‐based monolithic HPLC columns
Authors: Altmaier Stephan , Cabrera Karin 
Published: July 2008

AbstractSilica‐based monolithic columns were prepared for HPLC with systematic variations of the tetramethoxysilane (TMOS) and polyethylene oxide (PEO) content as reactants in a sol–gel process accompanied by phase separation. The resulting monoliths showed differences in the macropore and silica skeleton diameter as well as in the corresponding domain sizes (the sum of macropore and skeleton diameter). All monoliths were synthesized with a diameter of 4.6 mm and cladded with a suitable polyaryletheretherketone (PEEK) polymer in a standardized and optimized manner for the subsequent chromatographic evaluation of the resulting monolithic HPLC columns. The columns were tested under normal phase conditions using n‐heptane/dioxane (95:5 v/v) as a mobile phase and 2‐nitroanisole as a test compound for the determination of separation efficiency and permeability. Two different sets of columns were prepared: the first one in which the amount of PEO was stepwise decreased to yield monoliths with identical macropore volumes and variations in the domain sizes. The second group of materials was synthesized adjusting both TMOS and PEO quantities to yield monolithic columns with identical macropore diameters of about 1.80 μm but different skeleton diameters and macropore volumes. The chromatographic results suggest that an increase in the column performance cannot be achieved by just arbitrarily decreasing the domain size of a given column. From a certain point of “downsizing” the monolithic structure a loss of structural homogeneity can be observed, which is apparently responsible for a lower chromatographic performance.
Labour market and skills needs of the tourism and related sectors in Wales
Authors: Haven‐Tang Claire , Jones Eleri 
Published: July 2008

AbstractThis paper assesses labour market and skills needs of tourism and related sectors in Wales to inform policy responses by government and Sector Skills Councils. Micro‐businesses, many lifestyle businesses not appreciating the links between skills, training and competitiveness, and typically not undertaking training, dominate Welsh tourism. Sectoral fragmentation challenges the development of a coherent employer perspective. Official statistics provide incomplete, inaccurate information. Employer interviews identify skills gaps and persistent recruitment difficulties with responses including downsizing, deskilling and overseas recruitment. Public sector interventions may better target employer demand for skills and training to support a destination‐level service quality strategy than training supply. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of the dynamics of coal char combustion with ignition and extinction phenomena: Shrinking core model
Authors: Sadhukhan Anup Kumar , Gupta Parthapratim , Saha Ranajit Kumar 
Published: July 2008

AbstractSingle‐particle combustion of coal char is analyzed using a generalized shrinking core model. Finite volume method, which was earlier employed by the authors in solving moving boundary problems involving fluid–solid noncatalytic reactions in general, is used to solve fully transient mass and energy equations. The model takes into account convection and diffusion inside the particle as well as in the boundary layer. The computed results are compared with the experimental data of the authors for combustion of coal char in a fluidized bed combustor. The effects of parameters such as bulk temperature and initial particle radius on the combustion dynamics are examined. The phenomena of ignition and extinction are also investigated. Finally, the importance of Stefan flow, originating due to nonequimolar counterdiffusion, on combustion of coal char is analyzed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 569–582, 2008