bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous quantitative analysis of ketanserin and ketanserinol in plasma by RP‐HPLC with ﬂuorescence detection
Authors: Yassen A. , Hanff L. M. , Vulto A. G. 
Published: December 2003

AbstractA sensitive and selective high‐performance liquid chromatographic assay for the quantiﬁcation of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT‐1 solid‐phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 × 4.5 mm, 3 µm particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9–methanol–acetonitrile (52:40:8, v/v/v). Detection was performed with ﬂuorescence detection (λex = 332 nm and λem = 410 nm). Calibration curves were linear (r2 = 0.999) in the range 0–400 ng/mL for both ketanserin and ketanserinol. The repeatability coefﬁcient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefﬁcient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantiﬁcation for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed. Copyright © 2003 John Wiley & Sons, Ltd.
Applications of computer simulation in mechanism teaching
Authors: Fu Tseng‐Ti 
Published: December 2003

AbstractThe scope of implementing commercially available dynamics software as an aid to mechanism teaching and research in the university is reviewed. Based on the computer simulation, it has been applied to demonstrations in mechanism teaching, system learning and validation, and performance predictions. They are found useful in raising students' interests by vivid graphics, and impressing them with almost the same effect as dealing with real mechanisms. Despite the complexity of numerical schemes, the effort would be paid off by the flexibility and economy in modeling various systems with fewer limitations. The applications can be easily adapted to the specific needs of learning and in future network education. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 156–165, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10043
An interactive software package for the investigation of hydrodynamic‐slider bearing‐lubrication
Authors: Ozalp A. Alper , Ozel S. Ayse 
Published: December 2003

AbstractThe temperature dependent character of viscosity complicates the numerical analysis of hydrodynamic slider bearings and the geometry of the flow cavity plays a significant role on the design and performance of the lubrication systems. In this paper, we represent a recent software tool, named as “HYDRO‐LUB,” capable of performing constant and variable viscosity runs in various pad styles with moving boundaries. Results of the demonstrating project are not only consistent with the available literature but also show the fast and reliable character of the package; which in return put forward the advantages of applying the program in the lubrication courses of mechanical engineering. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 103–115, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10047
Metal‐Chelating Amino Acids As Building Blocks For Synthetic Receptors Sensing Metal Ions And Histidine‐Tagged Proteins
Authors: Hutschenreiter Silke , Neumann Lars , Rädler Ulf , Schmitt Lutz , Tampé Robert 
Published: December 2003

AbstractProtein structure and function rely on a still not fully understood interplay of energetic and entropic constraints defined by the permutation of the twenty genetically encoded amino acids. Many attempts have been undertaken to design peptide–peptide interaction pairs and synthetic receptors de novo by using this limited number of building blocks. We describe a rational approach to creating a building block based on a tailored metal‐chelating amino acid. Nε,Nε‐bis(carboxymethyl)‐L‐lysine can be flexibly introduced into peptides by 9‐fluorenylmethoxycarbonyl solid‐phase chemistry. The corresponding metal‐chelating peptides act as metal sensors and synthetic receptors for histidine‐tagged proteins. These biochemical tweezers will open new ways to control protein–protein interactions, to design peptide‐based interaction pairs, or to generate switchable protein function.
Intracellular Delivery of Bioactive Peptides to RBL‐2H3 Cells Induces β‐Hexosaminidase Secretion and Phospholipase D Activation
Authors: Howl John , Jones Sarah , Farquhar Michelle 
Published: December 2003

AbstractThis investigation compared the secretory efficacies of a series of peptides delivered to the cytoplasm of RBL‐2H3 mast cells. Mimetic peptides, designed to target intracellular proteins that regulate cell signalling and membrane fusion, were synthesised as transportan 10 (TP10) chimeras for efficient plasma membrane translocation. Exocytosis of β‐hexosaminidase, a secretory lysosomal marker, indicated that peptides presenting sequences derived from protein kinase C (PKC; C1 H‐CRRLSVEIWDWDL‐NH2) and the CB1 cannabinoid receptor (C3 H‐RSKDLRHAFRSMFPSCE‐NH2) induced β‐hexosaminidase secretion. Other peptide cargoes, including a Rab3A‐derived sequence and a homologue of C3, were inactive in similar assays. Translocated C1 also activated phospholipase D (PLD), an enzyme intimately involved in the regulated secretory response of RBL‐2H3 cells, but C1‐induced secretion was not dependent upon phosphatidate synthesis. Neither down‐regulation of Ca2+‐sensitive isoforms of PKC nor the application of a selective PKC inhibitor attenuated the secretory efficacy of C1. These observations indicate that the molecular target of C1 is a protein involved in the regulated secretory pathway that is upstream of PLD but is not a PKC isoform. This study also confirmed that TP10 is a relatively inert cell‐penetrating vector and is, therefore, widely suitable for studies in cells that are sensitive to peptidyl secretagogues.
Prion Diseases: From Molecular Biology to Intervention Strategies
Authors: Nunziante Max , Gilch Sabine , Schätzl Hermann M. 
Published: December 2003

AbstractPrion diseases are fatal neurodegenerative infectious disorders for which no therapeutic or prophylactic regimens exist. Understanding the molecular process of conformational conversion of the cellular prion protein (PrPc) into its pathological isoform (PrPSc) will be necessary to devise effective antiprion strategies. In recent years, new findings in the cell biology of PrPc, in the molecular pathogenesis of PrPSc, and in the cellular quality control mechanisms involved in these scenarios have accumulated. A function of the prion protein in signalling, the possible impact of the proteasome, and aggresomes as intracellular waste deposits have been described. Here, important pathogenetic similarities with the more frequent neurodegenerative disorders are evident. The need for therapeutic, postexposure, and prophylactic possibilities was drastically illustrated by the emergence of variant Creutzfeldt–Jakob disease (vCJD), a new human prion disease caused by bovine spongiform encephalopathy (BSE) derived prions. Although prion infectivity in humans is usually restricted to the central nervous system, in vCJD patients prions are present in the lympho‐reticular system, posing a theoretical risk of accidental human‐to‐human transmission. A variety of chemical antiprion substances have been reported in in vitro and cell culture based assays or in animal studies. Occasionally, they have also made their way into the first human trials. In addition, various promising interference strategies have been devised in transgenic models, although they are usually hard to transfer into nontransgenic in vivo situations. New findings in the fields of peripheral prion pathogenesis and immune system involvement fuelled the search for antiprion strategies formerly considered to be entirely impossible. This opened the door towards classical immunological interference techniques. Remarkably, passive and even active vaccination approaches now seem to be realistic goals.
Functionalizing Nanocrystalline Metal Oxide Electrodes With Robust Synthetic Redox Proteins
Authors: Topoglidis Emmanuel , Discher Bohdana M. , Moser Christopher C. , Dutton P. Leslie , Durrant James R. 
Published: December 2003

AbstractDe novo designed synthetic redox proteins (maquettes) are structurally simpler, working counterparts of natural redox proteins. The robustness and adaptability of the maquette protein scaffold are ideal for functionalizing electrodes. A positive amino acid patch has been designed into a maquette surface for strong electrostatic anchoring to the negatively charged surfaces of nanocrystalline, mesoporous TiO2 and SnO2 films. Such mesoporous metal oxide electrodes offer a major advantage over conventional planar gold electrodes by facilitating formation of high optical density, spectroelectrochemically active thin films with protein loading orders of magnitude greater (up to 8 nmol cm−2) than that achieved with gold electrodes. The films are stable for weeks, essentially all immobilized‐protein display rapid, reversible electrochemistry. Furthermore, carbon monoxide ligand binding to the reduced heme group of the protein is maintained, can be sensed optically and reversed electrochemically. Pulsed UV excitation of the metal oxide results in microsecond or faster photoreduction of an immobilized cytochrome and millisecond reoxidation. Upon substitution of the heme‐group Fe by Zn, the light‐activated maquette injects electrons from the singlet excited state of the Zn protoporphyrin IX into the metal oxide conduction band. The kinetics of cytochrome/metal oxide interfacial electron transfer obtained from the electrochemical and photochemical data obtained are discussed in terms of the free energies of the observed reactions and the electronic coupling between the protein heme group and the metal oxide surface.
Adhesion Inhibition of F1C‐Fimbriated Escherichia coli and Pseudomonas aeruginosa PAK and PAO by Multivalent Carbohydrate Ligands
Authors: Autar Reshma , Khan A. Salam , Schad Matthias , Hacker Jörg , Liskamp Rob M. J. , Pieters Roland J. 
Published: December 2003

AbstractIn order to evaluate their inhibition of bacterial adhesion, the carbohydrate sequences GalNAcβ1→4Gal and GalNAcβ1→4Galβ1→4Glc were synthesized. The disaccharide was conjugated to dendrons based on the 3,5‐di‐(2‐aminoethoxy)‐benzoic acid branching unit to yield di‐ and tetravalent versions of these compounds. A divalent compound was also prepared that had significantly longer spacer arms. Relevant monovalent compounds were prepared for comparison. Their anti‐adhesion properties against F1C‐fimbriated uropathogenic Escherichia coli were evaluated in an ELISA‐type assay by using a recombinant strain and also by using Pseudomonas aeruginosa strains PAO and PAK. Adhesion inhibition was observed in all cases, and multivalency effects of up to one order of magnitude were observed. The combination of spacer and multivalency effects led to a 38‐fold increase in the potency of a divalent inhibitor with long spacer arms towards the PAO strain when compared with the free carbohydrate.
Microwave‐Assisted Chemical Reactions
Authors: Nüchter M. , Müller U. , Ondruschka B. , Tied A. , Lautenschläger W. 
Published: December 2003

AbstractThis article reviews the state of the art of microwave‐assisted reactions and the influence of microwaves on mass and heat transfer. The heating behavior of representative test reactions and single substances is compared for heating with microwaves and thermal energy. Similarities and differences between convective heating and dielectric irradiation methods are discussed with regard to the yield, the selectivity, and the enantiomeric purity of the reaction products. Furthermore, prevailing problems related to the scale‐up of microwave‐assisted reactions are discussed considering the energy absorption of the substances and mixtures to be heated, and their dependence on the energy consumption and the amount of substance.
Hydrodynamics and Mass Transfer in Gas‐Liquid‐Solid Circulating Fluidized Beds
Authors: Liu Z. , Vatanakul M. , Jia L. , Zheng Y. 
Published: December 2003

AbstractAlthough extensive work has been performed on the hydrodynamics and gas‐liquid mass transfer in conventional three‐phase fluidized beds, relevant documented reports on gas‐liquid‐solid circulating fluidized beds (GLSCFBs) are scarce. In this work, the radial distribution of gas and solid holdups were investigated at two axial positions in a GLSCFB. The results show that gas bubbles and solid particles distribute uniformly in the axial direction but non‐uniformly in the radial direction. The radial non‐uniformity demonstrates a strong factor on the gas‐liquid mass transfer coefficients. A local mass transfer model is proposed to describe the gas‐liquid mass transfer at various radial positions. The local mass transfer coefficients appear to be symmetric about the central line of the riser with a lower value in the wall region. The effects of gas flow rates, particle circulating rates and liquid velocities on gas‐liquid mass transfer have also been investigated.
Novel Liquid‐Flow Splitting Unit Specifically Made for Numbering‐Up of Liquid/Liquid Chemical Microprocessing
Authors: Schenk R. , Hessel V. , Hofmann C. , Löwe H. , Schönfeld F. 
Published: December 2003

AbstractA liquid‐flow splitting unit for dividing one main liquid stream into six substreams was developed without the need for active flow regulation. The tool has six fluid connectors that allow the numbering‐up of a respective number of microprocess devices for liquid or liquid/liquid processes. One such liquid/liquid process for which the current tool design and tests in particular have been conceived, is the forced precipitation of precious inorganic powders by the segmented flow tubular reactor (SFTR) technique. Such investigations were performed with six micromixers of impinging‐jet or interdigital separation layer type attached to the liquid‐flow splitting unit. Fluid equipartition is achieved via the action of the microdevices as flow resistors, thereby increasing the pressure drop of the system. Liquid splitting was carried out in a cylindrical liquid tank with one inlet and six outlet holes that also served for pulsation dampening. By CFD simulations the impact of two important geometric parameters of this tank, namely, the height at a given diameter and the position of the inlet hole, on the fluid splitting was studied. In addition, the influence of the injection direction with respect to the normal of the tank was analyzed. It turned out that in the presence of flow resistors (typically generating a pressure drop at about 60 mbar) this impact is negligible, i.e., principally, a large flexibility on design and operation is provided. Without these resistors, the before‐mentioned parameters in turn have a large impact that is discussed in detail. Experiments with a liquid‐flow splitting unit and six coupled impinging‐jet micromixers using water as liquid proved a reasonable fluid distribution with a standard and maximum deviation of the substream flow rates of 4 and 11 %, respectively. These deviations are mainly caused by different pressure drops (Δp) of the individual impinging‐jet mixers as a result of tolerances in the microfabrication method, die sinking μEDM manufacture. Already small differences in the microstructured outlet hole diameters (d = 300 μm) of the impinging‐jet mixer have a large influence due to the d–4 ∼ Δp dependence. Additionally, attaching specially adapted interdigital separation layer micromixers to the liquid‐flow splitting unit, a minimum/maximum (standard) deviation of the water distribution below 5 (2) % could be achieved. To obtain this improved result, it was necessary to optimize the choice of material, the design of the microstructure inside the mixer, and the fabrication process.
Aggregation and loss of cytokeratin filament networks inhibit Golgi organization in liver‐derived epithelial cell lines
Authors: Kumemura Hiroto , Harada Masaru , Omary M. Bishr , Sakisaka Shotaro , Suganuma Tatsuo , Namba Masayoshi , Sata Michio 
Published: December 2003

AbstractIntermediate filaments are one of the three major cytoskeletons. Some roles of intermediate filaments in cellular functions have emerged based on various diseases associated with mutations of cytokeratins. However, the precise functions of intermediate filament are still unclear. To resolve this, we manipulated intermediate filaments of cultured cells by expressing a mutant cytokeratin. Arginine 89 of cytokeratin18 plays an important role in intermediate filament assembly. The expression of green fluorescent protein‐tagged cytokeratin18 arg89cys induced aggregations and loss of the intermediate filament network composed of cytokeratins in liver‐derived epithelial cells, Huh7 and OUMS29, but only induced the formation of cytokeratin aggregates and did not affect the intermediate filament network of endogenous vimentin in HEK293. The expression of this mutant affected the distribution of Golgi apparatus and the reassembly of Golgi apparatus after perturbations by nocodazole or brefeldin A in both Huh7 and OUMS29, but not in HEK293. Our data show that loss of the original intermediate filament network, but not the existence of cytokeratin aggregates, induces redistribution of the Golgi apparatus. The original intact intermediate filament network is necessary for the organization of Golgi apparatus. Cell Motil. Cytoskeleton 57:37–52, 2004. © 2003 Wiley‐Liss, Inc.
Higher plant cortical microtubule array analyzed in vitro in the presence of the cell wall
Authors: Tian Guo‐Wei , Smith Damien , Glück Susanne , Baskin Tobias I. 
Published: December 2003

AbstractPlant morphogenesis depends on an array of microtubules in the cell cortex, the cortical array. Although the cortical array is known to be essential for morphogenesis, it is not known how the array becomes organized or how it functions mechanistically. Here, we report the development of an in vitro model that provides good access to the cortical array while preserving the array's organization and, importantly, its association with the cell wall. Primary roots of maize (Zea mays) are sectioned, without fixation, in a drop of buffer and then incubated as desired before eventual fixation. Sectioning removes cytoplasm except for a residuum comprising cortical microtubules, vesicles, and fragments of plasma membrane underlying the microtubules. The majority of the cortical microtubules remain in the cut‐open cells for more than 1 h, fully accessible to the incubation solution. The growth zone or more mature tissue can be sectioned, providing access to cortical arrays that are oriented either transversely or obliquely to the long axis of the root. Using this assay, we report, first, that cortical microtubule stability is regulated by protein phosphorylation; second, that cortical microtubule stability is a function of orientation, with divergent microtubules within the array depolymerizing within minutes of sectioning; and third, that the polarity of microtubules in the cortical array is not uniform. These results suggest that the organization of the cortical array involves random nucleation followed by selective stabilization of microtubules formed at the appropriate orientation, and that the signal specifying alignment must treat orientations of ± 180° as equivalent. Cell Motil. Cytoskeleton 57:26–36, 2004. © 2003 Wiley‐Liss, Inc.
Developmental distribution of reelin‐positive cells and their secreted product in the rodent spinal cord
Authors: Kubasak Marc D. , Brooks Rona , Chen Songbo , Villeda Saul A. , Phelps Patricia E. 
Published: December 2003

AbstractTo date, only sympathetic and parasympathetic preganglionic neurons are known to migrate abnormally inreelermutant spinal cord. Reelin, the large extracellular matrix protein absent inreeler, is found in wild‐type neurons bordering both groups of preganglionic neurons. To understand better Reelin's function in the spinal cord, we studied its developmental expression in both mice and rats. A remarkable conservation was found in the spatiotemporal pattern of Reelin in both species. Numerous Reelin‐expressing cells were found in the intermediate zone, except for regions containing somatic and autonomic motor neurons. A band of Reelin‐positive cells filled the superficial dorsal horn, whereas only a few immunoreactive cells populated the deep dorsal horn and dorsal commissure. High levels of diffuse Reelin product were detected in the lateral marginal and ventral ventricular zones in both rodent species. This expression pattern was detected at all segmental spinal cord levels during embryonic development and remained detectable at lower levels throughout the first postnatal month. To discriminate between the cellular and secreted forms of Reelin, brefeldin A was used to block secretion in organotypic cultures. Such perturbations revealed that the high levels of secreted Reelin in the lateral marginal zone were derived from varicose axons of more medially located Reelin‐positive cells. Thus, the laterally located secreted Reelin product may normally prevent the preganglionic neurons from migrating too far medially. Based on the strong evolutionary conservation of Reelin expression and its postnatal detection, Reelin may have other important functions in addition to its role in neuronal migration. J. Comp. Neurol. 468:165–178, 2004. © 2003 Wiley‐Liss, Inc.
A study of prebiotic evolution
Authors: Corbet Aaron 
Published: December 2003

AbstractA very simple model prebiotic system is explored, both, to elucidate the full complexity of its dynamic behavior, and from the standpoint of what a thermal analysis can tell us about evolution more generally. The system consists of a coacervate containing a four variable enzymatic oscillator that is driven by a single input concentration. The reaction scheme is “nested”; i.e., by “turning on” one reaction at a time we can go from a two‐variable system, to one of three variables, to one of four, each developing more complex behavior. The four‐variable system is shown to have at least five distinct genera of complex attractors within the range examined. Two of these coexist for the same parameter values; the other three are substantially separated in the bifurcation space. The fixed points, characteristic roots, Lyapunov exponents, stability (dissipation), Kaplan‐Yorke dimensions, and correlation dimensions are all calculated for each attractor. A six‐variable amplification of the reaction scheme is considered as a simple model of nucleation in a coacervate and is shown to totally stabilize the corresponding attractor. An Evolutionary Potential is proposed that is wholly beyond the purview of classical thermostatics, yet incorporates entropy effects via Clausius' strong version of the Second Law. It is shown that the latter is a necessary condition for the sort of structuring characteristic of living systems. © 2003 Wiley Periodicals, Inc. Complexity 8: 45–67, 2003
Variable segmentation based on intrinsic video rate characteristics to transport pre‐stored video across networks
Authors: Fu Huirong , Zhang Liren 
Published: December 2003

AbstractA variable segmentation scheme based on intrinsic video rate characteristics (VSIVRC) is proposed for efficient dynamic bandwidth allocation to transport pre‐stored variable bit rate (VBR) video across networks. The proposed scheme is evaluated with a set of real‐life MPEG video traces and also compared with two fixed segmentation schemes: equal data segmentation (EDS) and equal frame segmentation (EFS). The obtained results show that the proposed VSIVRC scheme significantly outperforms both EDS and EFS in terms of range of selective bandwidth, matchness between arrival stream and playback stream, buffer occupancy and bandwidth allocation as well. Copyright © 2003 John Wiley & Sons, Ltd.