bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interconversion of intra‐ and extra‐chromosomal sites of gene amplification by modulation of gene expression and DNA methylation
Authors: Shimizu Noriaki , Hanada Naoyuki , Utani Kohichi , Sekiguchi Naoki 
Published: March 2007

AbstractWe previously showed that plasmids containing a mammalian replication initiation region and a matrix attachment region were efficiently amplified to few thousand copies per cell, and that they formed extrachromosomal double minutes (DMs) or chromosomal homogeneously staining regions (HSRs). In these structures, the plasmid sequence was arranged as a tandem repeats, and we suggested a mechanism of plasmid amplification. Since amplification was very efficient, easy, and convenient, it might be adapted to a novel method for protein production. In the current study, we found that gene expression from the tandem plasmid repeat was suppressed. We identified several strategies to overcome this suppression, including: (1) use of higher concentrations of antibiotic during cell selection; (2) treatment of cells with agents that influence DNA methylation (5‐azacytidine) or histone acetylation (butyrate); (3) co‐amplification of an insulator sequence; and (4) co‐amplification of sequences that encode a transcriptional activator. Expression from the plasmid repeat was always higher at DMs compared to HSRs. We found that continuous activation of a plasmid‐encoded inducible promoter prevented the generation of long HSRs, and favored amplification at DMs. Consistent with this finding, there was a synergistic effect of transcriptional activation and inhibition of DNA methylation on the fragmentation of long HSRs and the generation of DMs and short HSRs. Our results indicate that both transcriptional activation and DNA methylation regulate the interconversion between extra‐ and intra‐chromosomal gene amplification. These results have important implications for both protein production technology, and the generation of chromosomal abnormalities found in human cancer cells. J. Cell. Biochem. 102: 515–529, 2007. © 2007 Wiley‐Liss, Inc.
Pressurized liquid extraction of pharmaceuticals from sewage‐sludge
Authors: Nieto Antonio , Borrull Francesc , Pocurull Eva , Marcé Rosa Maria 
Published: March 2007

AbstractA method for the quantitative determination of ten pharmaceuticals in sewage sludge was developed by using pressurized liquid extraction (PLE) and HPLC–MS with ESI (HPLC‐(ESI)MS). The PLE was optimized with regard to solvents and operational parameters, such as temperature, pressure, extraction time, and purge time. The optimum conditions were: 50 mM phosphoric acid/methanol (1:1 v/v) as the extraction solvent, temperature of 100°C, pressure of 100 bar, extraction time 15 min, 2 cycles, flush volume 150% and purge time 300 s. All recoveries for pharmaceuticals were over 68% except for salicylic acid. The repetitivity and reproducibility between days expressed as RSD was lower than 8% for repetitivity and 10% for reproducibility. The LOD of all compounds was lower than 10 μg/kg of dry weight of sewage sludge. The method was applied to determine the pharmaceuticals in sewage sludge from two domestic sewage treatment plants (STPs). The samples were collected every three months between February 2004 and June 2005. Some pharmaceuticals were determined in the samples and naproxen showed the highest value (242 μg/kg of dry weight).
Selectivity in reversed‐phase separations: General influence of solvent type and mobile phase pH
Authors: Neue Uwe D. , Méndez Alberto 
Published: March 2007

AbstractThe influence of the mobile phase on retention is studied in this paper for a group of over 70 compounds with a broad range of multiple functional groups. We varied the pH of the mobile phase (pH 3, 7, and 10) and the organic modifier (methanol, acetonitrile (ACN), and tetrahydrofuran (THF)), using 15 different stationary phases. In this paper, we describe the overall retention and selectivity changes observed with these variables. We focus on the primary effects of solvent choice and pH. For example, transfer rules for solvent composition resulting in equivalent retention depend on the packing as well as on the type of analyte. Based on the retention patterns, one can calculate selectivity difference values for different variables. The selectivity difference is a measure of the importance of the different variables involved in method development. Selectivity changes specific to the type of analyte are described. The largest selectivity differences are obtained with pH changes.
Effect of Blend Preparation on Electrical, Dielectric, and Dynamical‐Mechanical Properties of Conducting Polymer Blend: SBS Triblock Copolymer/Polyaniline
Authors: Soares Bluma G. , Leyva Maria Elena 
Published: March 2007

AbstractConducting polymer blends based on styrene–butadiene–styrene (SBS) triblock copolymer and polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) were prepared by different procedures: mechanical mixing (MM) and ‘in situ’ polymerization (ISP) methods. The ISP blends exhibited higher levels of electrical conductivity, as compared to MM blends. The scanning electron micrographs of the ISP blend were characterized by the presence of microtubules, which favored the formation of the conducting pathways inside the SBS matrix. From dynamic mechanical and dielectric analysis, it was possible to suggest a higher interaction degree of the polyaniline with the polystyrene phase of the block copolymer. Blends prepared by ISP method displayed also higher dielectric constant and higher dielectric loss factor than blends prepared by MM method.magnified image
Diffusion of Model Contaminants in High‐Density Polyethylene
Authors: Voultzatis Ioannis S. , Papaspyrides Constantine D. , Tsenoglou Christos J. , Roussis Constantine 
Published: March 2007

AbstractFour liquid solvents – 1,1,1‐trichloroethane, toluene, chlorobenzene and octane – are used as model contaminants in sorption experiments in polyethylene in order to study their diffusion behavior between 40 and 70 °C and assess the plausibility of utilizing recycled plastics as safe functional barriers in food packaging applications. A hybrid model that combines molecular and free volume theory elements is used to interpret the collected experimental data. This helps in evaluating microstructural characteristics pertaining to the penetrant‐polymer systems tested, correlating these characteristics with the molecular properties of the solvent, and has an eventual role in predicting sorption and diffusivity in similar untested systems.magnified image
Diagnosis of Abnormal Situations in a Continuous Solution Polymerization Reactor
Authors: Sotomayor Oscar A. Z. , Odloak Darci , Giudici Reinaldo 
Published: March 2007

AbstractThis work presents results on the problem of robust on‐line diagnosis of abnormal situations in the case of the free‐radical solution polymerization of styrene in a continuous well‐mixed reactor operating under feedback control. The control system is constituted of a model predictive control strategy in conjunction with a ratio control law. The proposed fault diagnosis system is based on an open‐loop approach, which uses a linearized model of the polymerization process for the implementation of a bank of reduced‐order unknown input observers. Each observer is designed to detect changes in a particular process parameter, external disturbance or malfunctioning of sensors and actuators. Fault isolation is obtained through a structured residual approach; meanwhile, fault estimation is performed using the degree of freedom remaining in the observer design. The effectiveness of the proposed technique is verified through numerical simulations carried out on a well‐defined industrial styrene polymerization benchmark.magnified image
Compartmentalization in TEMPO‐Mediated Radical Polymerization in Dispersed Systems: Effects of Macroinitiator Concentration
Authors: Zetterlund Per B. , Okubo Masayoshi 
Published: March 2007

AbstractThe influence of the initial macroinitiator concentration ([PT]0) on compartmentalization effects (segregation effects and confined space effects) in 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO)‐mediated radical polymerization of styrene in a dispersed system at 125 °C has been investigated by simulations employing modified Smith‐Ewart equations. The modeling approach accounts for compartmentalization of both propagating radicals and nitroxide, as well as the generation of radicals by thermal initiation of styrene. The manifestation of compartmentalization effects occurs at significantly greater particle diameters (d) for low [PT]0; at [PT]0 = 0.002 M, the polymerization rate, control and livingness are affected by compartmentalization for d < 120 nm, whereas the system behaves as in the corresponding bulk system for d > 45 nm at [PT]0 = 0.2 M. The results are discussed with regards to the specific effects of compartmentalization on deactivation and bimolecular termination.magnified image
An operator method for a numerical quadrature finite element method for a Maxwell‐eigenvalue problem
Authors: Hamelinck Wouter , Van Keer Roger 
Published: March 2007

AbstractWe consider a Maxwell‐eigenvalue problem on a brick. As is well known, we need to pay special attention to avoiding the so‐called spurious eigenmodes. We extend the results obtained in (SIAM J. Numer. Anal. 2000; 38:580–607) to include the use of numerical quadrature. For simplicity, we restrict ourselves to a Gauss–Lobatto integration scheme. The numerical quadrature variational problem can be recasted in an operator form. The main goal of the article consists of proving that a set of necessary and sufficient conditions for spurious freeness remain valid while using numerical quadrature with sufficient precision. Copyright © 2007 John Wiley & Sons, Ltd.
A GC‐FID method for analysis of Lysinoalanine
Authors: Montilla Antonia , Gómez‐Ruiz José Ángel , Olano Agustín , del Castillo María Dolores 
Published: March 2007

AbstractLysinoalanine (LAL) is an unwanted byproduct, which is formed during the processing of protein and protein‐containing foods and feeds. A GC method for the quantitative analysis of LAL under conventional chromatographic conditions has been developed. The method was applied to the analysis of pure standard substances, boiled eggs, commercial caseinates, fresh cheese, fresh cheese made from milk supplemented with caseinate, and fresh cheeses adulterated with caseinate after cheese making process. Results demonstrated the reliability of the GC capillary chromatography for the analysis of LAL in protein containing foods. LOD and LOQ of 50 and 152 ppm of LAL in protein, respectively, were achieved. Range of linearity, precision, and accuracy of the method, measured using diaminopimelic acid as internal standard, were satisfactory for quantification purpose. The method might also be suitable for the quantitative analysis of other amino acids such as lysine and arginine. Results also indicated the utility of this methodology for detecting protein quality of egg products and caseinates as well as fresh cheese adulterations.
Copper‐catalyzed ascorbate oxidation results in glyoxal/AGE formation and cytotoxicity
Authors: Shangari Nandita , Chan Tom S. , Chan Katie , Huai Wu Shuo , O'Brien Peter J. 
Published: March 2007

AbstractPreviously we showed that 10 μM glyoxal compromised hepatocyte resistance to hydrogen peroxide (H2O2) by increasing glutathione (GSH) and NADPH oxidation and decreasing mitochondrial membrane potential (MMP) before cytotoxicity ensued. Since transition metal‐catalyzed oxidation of ascorbate (Asc) has been shown to result in the generation of both glyoxal and H2O2, we hypothesized that glyoxal formation during this process compromises hepatocyte resistance to H2O2. We used isolated rat hepatocytes and incubated them with Asc/copper and measured cytotoxicity, glyoxal levels, H2O2, GSH levels, and MMP. To investigate the role of Asc/copper on glyoxal‐BSA adducts, we measured the appearance of advanced glycation end‐products (AGE) in the presence and absence of catalase or aminoguanidine (AG). Asc/copper increased glyoxal and H2O2 formation. Hepatocyte GSH levels were decreased and cytotoxicity ensued after a collapse of the hepatocyte MMP. Glyoxal traps protected hepatocytes against Asc/copper‐induced cytotoxicity. In cell‐free studies with BSA, incubation with Asc and copper resulted in glyoxal‐hydroimidazolone formation, which was decreased by both AG and catalase. To the best of our knowledge, this is the first study that illustrates the importance of glyoxal production by transition metal‐catalyzed Asc autoxidation. Understanding this mechanism of toxicity could lead to the development of novel copper chelating drug therapies to treat diabetic complications.
Reducing the formation of glucose degradation products in peritoneal dialysis solutions by ultrahigh temperature ohmic heating
Authors: Shapira Alina , Shazman Asher , Ungar Yael , Shimoni Eyal 
Published: March 2007

AbstractPeritoneal dialysis (PD) is commonly performed by using preprepared dialysis solutions containing glucose, which are thermally treated to achieve commercial sterilization. A series of glucose degradation products (GDPs) are being formed, which react with the tissue during the dialysis procedure, thus baring a negative effect on the patient and the dialysis process. The present study tested the efficacy of ohmic heating as an alternative thermal treatment for continuous sterilization of PD solutions. The process was compared to conventional retort treatment, and GDPs accumulation was measured. Thermal treatments using the ohmic heating system were performed at three temperatures (105, 125, and 150°C) with residence time at each temperature ranging from 0.84 to 12.0 s. The resulting concentrations of glyoxal (GO), methylglyoxal (MGO), and 3‐deoxyglucosone (3‐DG) in the PD solutions were measured. None of these GDPs were found in PD fluids treated by ohmic heating at 105°C. The concentration of 3‐DG, after a standard sterilization treatment (121°C, 20 or 40 min) was one order of magnitude higher (˜140 and 242 μM) than after ohmic heating treatment at 125°C. The results of the present study suggest that this technique can be used to produce solutions with much lower content of GDPs. It also demonstrates the advantage of using the ohmic heating technology as a tool for high temperature short time treatment of PD fluids.
The potential antimutagenic and antioxidant effects of Maillard reaction products used as “natural antibrowning” agents
Authors: Wagner Karl‐Heinz , Reichhold Stefanie , Koschutnig Karin , Chériot Sophie , Billaud Catherine 
Published: March 2007

AbstractThe aim of this study was to investigate the potential antioxidative and antimutagenic effects of Maillard reaction products (MRPs) formed from glucose or fructose and cysteine or glutathione in the Ames Salmonella test and the 2,2′‐azobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) assay. The mixtures were heated for 4 h 20 min or 14 h at 103 or 110°C and tested in five concentrations from 0.05 to 11 mg/plate in strains TA 98 and TA 102 in the plate incorporation assays. In order to promote the formation of mutant revertants the prooxidants hydrogenperoxide (H2O2) and tertiary‐butyl hydroperoxide (tBOOH) were used in the TA 102. Tests were conducted with preincubation with (+S9) and without (–S9) metabolic activation. 5‐Hydroxymethylfurfural (5‐HMF) was investigated as carbonyl compound. In TA 98, no effect of the MRPs was shown. The shorter heated samples (4 h 20 min) were in general more active than the longer heated ones (14 h). Up to 1 mg/plate (1%) all the reaction mixtures remained safe, but the 5% and in particular the 11% fractions increased the number of revertants significantly for the shorter heated mixtures. The 14 h mixtures did not show any response for almost all concentrations. No significant difference in the number of revertants could be observed between the cysteine and glutathione mixtures, the fructose mixtures increased revertants number to a higher extent than the glucose mixtures only in the 4 h 20 min heated mixtures for the highest concentration (11%). The highest activity was always observed in the +S9 tests. Antioxidative effects expressed as Trolox equivalents were higher in the 4 h 20 min heated samples. When detectable, HMF concentration was found to be higher in the 14 h MRP samples. In order to use the tested mixtures as antibrowning agents for technological purpose, the concentration should not be higher than 1% and the longer heated reaction mixtures were preferred since the brown pigments seemed to be less reactive than the intermediate products.
Forty years of furosine – Forty years of using Maillard reaction products as indicators of the nutritional quality of foods
Authors: Erbersdobler Helmut F. , Somoza Veronika 
Published: March 2007

AbstractThe Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of foods are furosine, Nε‐carboxymethyllysine (CML), hydroxymethylfurfural, pyrraline, pentosidine and pronyl‐lysine. One of the MRPs identified first was furosine, which was quantified in foods 40 years ago as a chemical indicator of the Amadori compound Nε‐fructoselysine. Since then, furosine has gained broad attention by food chemists and biomedical researchers, as its formation upon heat treatment is well characterised. Moreover, it represents the Amadori products from early Maillard reactions in which amino acids react with reducing carbohydrates, resulting in a loss of their availability. This is of importance for the essential amino acid lysine, which is also the limiting amino acid in many proteins. In order to evaluate the nutritional quality of a protein, the concomitant analysis of free – and nutritionally available – lysine and the amount of lysine reacted to form the respective MRP is essential, even for mildly processed foods. The other chemical markers of heat treatment such as CML, pyrraline, pentosidine or pronyl‐lysine seem to be useful markers of the advanced stages of Maillard reactions. Compared to the conditions in which furosine is formed, these compounds are generated under more severe conditions of heat treatment. However, the concentrations analysed are significantly lower than those of furosine. Therefore, the nutritional evaluation of a food protein should include not only furosine, but also other chemical markers of heat treatment such as, for example, CML, pyrraline and pentosidine.
A novel 1 × 2 multimode interference optical wavelength filter based on photodefinable benzocyclobutene (BCB 4024–40) polymer
Authors: Ibrahim M. H. , Kassim N. M. , Mohammad A. B. , Lee Shuh‐Ying , Chin Mee‐Koy 
Published: March 2007

AbstractA novel 1 × 2 multimode interference (MMI) optical wavelength filter for 1310 and 1550 nm operation based on photodefinable BenzoCyclobutene (BCB 4024–40) polymer is demonstrated. The device is fabricated on BK7 glass substrate with thin layer of SiO2 as cover. A cost effective chemical etching technique is used in the fabrication process to take advantage of the photosensitive nature of the polymer. The filter length is significantly reduced by adopting the restricted MMI scheme, lower beat length ratio, and cascaded MMI couplers. At 1550 nm filtering operation, the measured crosstalk is −20.6 dB and at 1310 nm filtering is −14.4 dB. The measured insertion loss is around 3.2–3.5 dB for both ports. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1024–1028, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22327
Effect of SNR of input signal on the accuracy of a ratiometric wavelength measurement system
Authors: Rajan Ginu , Wang Qian , Farrell Gerald , Semenova Yuliya , Wang Pengfei 
Published: March 2007

AbstractThe impact of a change in signal‐to‐noise ratio (SNR) of the input signal on the accuracy of a ratiometric wavelength measurement system is studied. The variation of the output ratio of the system due to the change in SNR of the input signal is modeled and the experimental investigation has been carried out, and both indicate that the accuracy is influenced significantly by variations in the SNR of the input signal. The demonstration example shows a wavelength shift of 0.055 nm when the SNR of the input signal varies from 47 dB to 42 dB (the measurable range is from 1500 nm to 1600 nm and the edge filter used has a slope of 0.15 dB/nm). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1022–1024, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22328
Frequency selective surfaces on ISO/anisotropic substrates with dielectric losses
Authors: Campos A. L. P. S. , d'Assunção A. G. 
Published: March 2007

AbstractThe analysis of periodic structures on isotropic and anisotropic substrates with dielectric losses is presented. Frequency selective surface structures composed by an array of conducting patch elements are considered. This analysis uses the Galerkin method in combination with the equivalent transmission line method, in the Fourier domain, to determine the reflection and transmission characteristics of the considered structures. The analysis provides very accurate results compared with those presented by other authors, for several particular cases. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1041–1044, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22334
Small size quad band microstrip antenna
Authors: Thakur Jay Prakash , Park Jun‐Seok , Jang Byoung‐Jun , Cho Hong‐Gu 
Published: March 2007

AbstractA novel compact microstrip patch antenna is proposed for quad band, GSM850, GSM900, GPS (L1–1575 and L2–1227), and UMTS‐2110 application for cellular telephone system. Design is particularly unique since it supports the new generation mobile phone where multiband operation with minimum size is greatly desired. Two microstrip line feeds placed in orthogonal directions are used for the excitation of the proposed antenna. Microstrip patch has been meandered to lengthen the electrical paths and to achieve quad frequency bands. Detail of design criteria with respect to physical parameters is described. Radiation Patterns and impedance bandwidths are measured and shown. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 997–1001, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22341
Transmission properties of two shifted magnetoinductive waveguides
Authors: Radkovskaya A. , Sydoruk O. , Shamonin M. , Stevens C. J. , Faulkner G. , Edwards D. J. , Shamonina E. , Solymar L. 
Published: March 2007

AbstractTransmission properties of magnetoinductive waves propagating in two coupled one‐dimensional metamaterial arrays are studied both experimentally and theoretically for the case when one of the arrays is shifted relative to the other one. Two different kinds of resonant metamaterial elements, split‐pipe and spiral resonators, are investigated in the frequency bands centred at 46.2 and 586 MHz, respectively. It is shown that within a certain frequency range close to the resonant frequencies the transmission is strongly dependent on the shift. Theoretical calculations based on the impedance matrix show good agreement with the experimental results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1054–1058, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22344