bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study of the creation of a fire‐rod II: Emissive probe measurements
Authors: Gyergyek T. , Čerček M. , Schrittwieser R. , Ionita C. , Popa G. , Pohoata V. 
Published: January 2003

AbstractA planar electrode (collector) is immersed into a weakly magnetized discharge plasma column. Positive voltage steps are applied to the collector and time resolved measurements of the plasma response are performed by emissive probes using standard boxcar technique. On the emissive probe characteristics an interesting phenomenon is observed: a few μs after the application of the voltage step to the collector (time depends on the distance between the collector and the probe), the emissive probe starts to collect additional positive current in the potential region between plasma potentials of the high and low potential plasma. This phenomenon is investigated experimentally. We give a possible qualitative explanation that additional positive current collection is due to a combination of an interaction between the collector and the probe and space charge effects of positive ions around the probe.
Stability criteria of Rayleigh ‐ Taylor modes in magnetized plasmas
Authors: Al–Khateeb A.M. , Laham N.M. 
Published: January 2003

AbstractThe Rayleigh ‐ Taylor (RT) instability is investigated analytically in an inhomogeneous plasma in an external magnetic field. For the case of two distinct fluid layers separated by a sharp boundary and for a fluid of a continuously varying density, RT dispersion relations have been obtained and analyzed. Stability criteria of the excited modes are disscussed with respect to the mode propagation relative to the applied magnetic field. The magnetic field is found to act as a stabilizer up to a threshold value that can be determined from the dispersion relation.
Interpolation formula for the electrical conductivity of nonideal plasmas
Authors: Esser A. , Redmer R. , Röpke G. 
Published: January 2003

AbstractOn the basis of a quantum‐statistical approach to the electrical conductivity of nonideal plasmas we derive analytical results in the classical low‐density regime, in the degenerate Born limit, and for the contribution of the Debye‐Onsager relaxation effect. These explicit results are used to construct an improved interpolation formula of the electrical conductivity valid in a wide range of temperature and density which allows to compare with available experimental data of nonideal plasmas.
Scattering processes and electrical conductivity of partially ionized hydrogen plasma
Authors: Ramazanov T. , Galiyev K. , Dzhumagulova K. N. , Röpke G. , Redmer R. 
Published: January 2003

AbstractWe consider partially ionized hydrogen plasma for the density region ne = (1018 ÷ 1022) cm—3. The cross sections for scattering processes between the particles are calculated within the partial wave method. Charged particles in the system (electrons, protons) interact via an effective potential that takes into account threeparticle correlations. The Buckingham polarization potential is used to describe electron‐atom and proton‐atom interactions. The electrical conductivity is determined using the Chapman‐Enskog method. The results are compared with other available data.
Flow cytometric quantification of apoptosis and proliferation in mixed lymphocyte culture
Authors: Marín Luis , Minguela Alfredo , Torío Alberto , Moya‐Quiles María R. , Muro Manuel , Montes‐Ares Olga , Parrado Antonio , Álvarez‐López D. María Rocío , García‐Alonso Ana M. 
Published: January 2003

AbstractBackgroundThe one‐way mixed lymphocyte culture (MLC) is the classic culture used for studying the allogenic immunoresponse in vitro, but stimulator and responder cell identifications and quantification of apoptotic or proliferative responder cells are unreliable.MethodsPeripheral blood mononuclear cells were labeled with 5‐ (and 6‐) carboxy fluorescein diacetate succinimidyl ester (CFSE) and stimulated with allogenic unlabeled irradiated cells in unidirectional cultures. Apoptosis was determined by the 7‐aminoactinomycin D technique, and the absolute number of each cell population was calculated by adding a fixed number of cells stained with propidium iodide as the reference standard for each test.ResultsCFSE labeling of cells under different cultures did not affect the results of proliferation or apoptosis. Data of apoptosis obtained with this method were comparable to those of the monoclonal antibody technique, and the proliferation level determined by [3H]‐thymidine incorporation or counting the number of proliferative living cells, as proposed in this method, showed a good correlation.ConclusionsThe method presented in this report allows the simultaneous determination of apoptosis and proliferation in MLCs and the analysis of cell phenotype, thereby avoiding the use of radioactivity. This assay opens new perspectives for a better understanding of the mechanisms implied in the establishment or break of tolerance to the graft in solid organ transplants. Cytometry Part A 51A: 107–118, 2003. © 2003 Wiley‐Liss, Inc.
Analysis‐only detection of Giardia by combining immunomagnetic separation and two‐color flow cytometry
Authors: Ferrari Belinda C. , Veal Duncan 
Published: January 2003

AbstractBackgroundGiardia is a protozoan parasite of concern to water utilities. Giardia detection relies on cyst isolation and confirmation with the use of fluorescence microscopy. It is of interest to develop a flow cytometric (FCM) method that reliably detects one cyst in 10 L of water. To date all available antibodies have targeted the same epitope on the cyst wall. To achieve a reliable method, two independent probes are required.MethodsGiardia cysts were spiked into a backwash water sample with and without prior hybridization to peptide nucleic acid (PNA) probes. Immunomagnetic separation (IMS) as a pre‐enrichment step was compared with filtration of the water sample. Cysts were recovered with two‐color FCM. Those cysts hybridized with PNA and fluorescein isothiocyanate (FITC) were dual stained with monoclonal antibody (mAb) conjugated to phycoerythrin (PE); those not hybridized to PNA were dual stained with mAb‐FITC and mAb‐PE.ResultsA fourfold increase in fluorescent signal intensity was obtained when combining the mAb‐PE and PNA probe compared with two‐color antibody staining. When combined with IMS, Giardia was successfully identified by FCM, with no false positives detected.ConclusionsAnalysis‐only FCM detection of Giardia in water is feasible. Further method development incorporating PNA probe hybridization after IMS is necessary. Cytometry Part A 51A:79–86, 2003. © 2003 Wiley‐Liss, Inc.
Quantifying cell scattering: The blob algorithm revisited
Authors: Kort Eric J. , Jones Ashley , Daumbach Michael , Hudson Eric A. , Buckner Bree , Resau James H. 
Published: January 2003

AbstractBackgroundA method to objectively quantify cell scattering would permit quantitative evaluation of therapies and compounds intended to affect this physiologic process, which has relevance to normal (e.g., development) and pathologic (e.g., metastasis) events.MethodsA grid‐based modified blob analysis was performed on a set of images of Madin‐Darby Canine Kidney (MDCK) cells to quantify the following parameters: the number of cellular clusters in each image, the size of the clusters in terms of pixel counts, and the number of cells in each cluster. These parameters were used as measures of cell scattering and were compared with subjective assessments of scattering made by three experienced examiners.ResultsThe quantitative parameters correlated strongly to subjective assessments. The algorithm displayed a different concept of “clustering” than the examiners and consistently identified more clusters than did the examiners. There was close agreement in the number of cells counted. All three quantitative parameters correlated strongly to the subjective scattering scores, as follows: cluster count (rs = −0.765 to −0.789, P < 0.0001), cluster size in pixels (rs = 0.838 to 0.845, P < 0.0001), and cluster size in cells (rs = 0.758 to 0.804, P < 0.0001). The parameters were continuous, providing greater resolving power than ordinal subjective scores.ConclusionsThe findings confirmed that our algorithm reproduces the traditional classification of scattering with improved resolution, quantification, and objectivity. Cytometry Part A 51A:119–126, 2003. © 2003 Wiley‐Liss, Inc.
Rapid expression cloning of receptors using epitope‐tagged ligands and high‐speed cell sorting
Authors: Robeva Anna S. , Yan‐Neale Yan , Burfeind Patricia , Bodian Dale L. , Chirn Gung‐Wei , Kolbinger Frank , Labow Mark , Vallon Rüdiger D. W. 
Published: January 2003

AbstractBackgroundIn this study we describe a new approach for expression cloning of receptors.MethodsOur approach was based on highly efficient transfer of retroviral cDNA libraries into target cells and detection of receptor–ligand interaction with the use of an antibody directed against an epitope tag on recombinant ligands. Detection of the complex and isolation of receptor‐transduced cells were achieved by flow cytometry and rare event high‐speed cell sorting. Recovery of the cDNA coding for the receptor(s) was achieved by polymerase chain reaction.ResultsAs a proof‐of‐concept study we set out to clone the receptor for B‐lymphocyte stimulator protein (BlyS), not known at the start of the project but reported while this work was in progress. First, we detected binding of epitope‐tagged BlyS to IM9 cells. Second, human T‐lymphoblasts (CEM cells), which do not bind BlyS, were transduced with a retroviral cDNA library generated from IM9 cells. Transduced CEM cells binding epitope‐tagged BlyS protein were identified by flow cytometry. After three sequential rounds of cell sorting, transduced CEM cell populations with high binding capacity for BlyS were identified. To determine the cDNAs conferring binding to the transduced CEM cells, the integrated proviral DNAs were amplified by polymerase chain reaction and analyzed by DNA sequencing. Rescued cDNAs contained Transmembrane Activator and calcium‐modulator and cyclophilin ligand (CAML) Interactor (TACI) and B‐Cell Maturation factor (BCMA) sequences, representing two published receptors of BlyS.ConclusionsOur data demonstrated that flow cytometry and high‐speed cell sorting combined with transduction of retroviral cDNA libraries and binding of epitope‐tagged orphan ligands as a selectable phenotype can be used efficiently for expression cloning of receptors. Of particular interest was our finding that apparently it is not necessary to purify the ligand but that conditioned medium containing the ligand can be used instead. Thus we concluded that our approach shortens the time to identify receptors for many orphan ligands and helps to exploit these receptors as drug targets. Cytometry Part A 51A:59–67, 2003. © 2003 Wiley‐Liss, Inc.
Automated flow cytometry for acquisition of time‐dependent population data
Authors: Abu‐Absi Nicholas R. , Zamamiri Abdelqader , Kacmar James , Balogh Steven J. , Srienc Friedrich 
Published: January 2003

AbstractBackgroundThe implementation of flow cytometry in many experimental settings can be limited by the extensive amount of sample handling and preparation required for analysis. We describe a system that automatically performs sample handling and flow cytometric analysis, thus allowing one to construct detailed pictures of changes in cell population distributions as a function of time.MethodsCell samples from bioreactors were loaded into a microchamber designed to perform all sample preparation steps including washing, fixation, staining, and dilution. The sample was then transported into a sample loop of known volume from which it was injected into the flow cell for determination of cell counts and measurement of scattering and fluorescence parameters. The apparatus was fully automated and controlled with a personal computer equipped with a data acquisition card. An inexpensive mechanism that continuously replenished the sheath fluid was implemented to ensure continuous and uninterrupted operation of the flow cytometer for several days. The device was interfaced with a FACSCalibur equipped with CellQuest software for data acquisition and analysis.ResultsThe set‐up was tested with batch cultures of Saccharomyces cerevisiae expressing the green fluorescent protein (GFP). On‐line cell counts showed close agreement with off‐line measurements throughout the exponential growth of a yeast culture. The time course of light scattering, GFP fluorescence, and viability distributions provided a detailed description of changes occurring in growing cell cultures based on sampling approximately every 15 min for more than 40 consecutive hours. Therefore, the device could be used to obtain descriptions of the dynamic behavior of cell populations with no user intervention required for several days.ConclusionsThe system significantly expanded the utility of flow cytometry by eliminating cumbersome and time‐consuming steps that make the application of flow cytometry impractical in certain situations. It is anticipated that the described set‐up will find utility in biotechnology applications such as monitoring of cell cultures, screening of biologically active compounds, and in functional genomics efforts for phenotypic characterizations of cells. Cytometry Part A 51A:87–96, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of the distribution of MRI contrast agents in the livers of small animals by means of complementary microscopies
Authors: Kahn E. , Tessier C. , Lizard G. , Petiet A. , Bernengo J.‐C. , Coulaud D. , Fourré C. , Frouin F. , Clément O. , Jourdain J.‐R. , Delain E. , Guiraud‐Vitaux F. , Colas‐Linhart N. , Siauve N. , Cuenod C.‐A. , Frija G. , Todd‐Pokropek A. 
Published: January 2003

AbstractBackgroundMagnetic resonance imaging (MRI) contrast agents contain magnetic molecules such as iron (Fe) or gadolinium (Gd) that are injected in vivo into rats or mice to study their distribution inside the liver. Fluorescent europium (Eu) can be used as a model of Gd to obtain comparable information of this distribution of corresponding contrast agents. In a similar approach, Fe can be attached to Texas Red and used as a model of ferumoxides and be detected by fluorescence.MethodsTo combine and compare the advantages of different microscopic imaging modes, characterization studies were carried out by means of a confocal laser scanning microscope (CLSM), a secondary ion mass spectrometric (SIMS) microscope, and an electron energy loss spectrometric (EELS) microscope. In the case of CLSM, the locations of fluorescent signals inside preparations were determined by factor analysis of biomedical image sequences (FAMIS) and selection of image sequences at emission.ResultsBy CLSM and FAMIS, we distinguished chelated Eu and Texas Red attached to Fe. By SIMS microscopy, we distinguished Eu and Gd of chlorides and chelates and Fe of a ferumoxide. By EELS microscopy, we distinguished Eu and Gd of chlorides.ConclusionsAnalysis of compounds inside correlative specimens by means of CLSM, SIMS, and EELS microscopes provided complementary results. Cytometry Part A 51A:97–106, 2003. © 2003 Wiley‐Liss, Inc.
Detection of β‐lactamase reporter gene expression by flow cytometry
Authors: Knapp Tom , Hare Eric , Feng Luxin , Zlokarnik Gregor , Negulescu Paul 
Published: January 2003

AbstractBackground:Flow cytometry of gene expression in living cells requires accurate, sensitive, nontoxic fluorescent indicators capable of detecting transcription of specific genes. This is typically achieved by using genes that encode fluorescent proteins or enzymes coupled to promoters of interest. The most commonly used reporters are green fluorescent protein and β‐galactosidase (lacZ). In this study, we characterized the performance of a cell‐permeant, ratiometric, β‐lactamase substrate, coumarin cephalosporin fluorescein (CCF2/AM). We compared its characteristics with that of the β‐galactosidase/fluorescein di‐β‐D‐galactopyranoside reporter system.Methods:Jurkat cell lines were generated for β‐lactamase and β‐galactosidase reporters with the use of similar plasmid constructs. Rare event flow cytometric detection for the β‐galactosidase and β‐lactamase reporters were assayed by using mixed populations of negative (WT) and positive (constitutively expressing) cells for each reporter. To determine sensitivity at low reporter copy number, we measured the activity of an unstimulated inducible promoter and detected positive events as a function of substrate incubation time. Technical issues related to data processing and optical configuration are also presented.Results:The low population coefficients of variation afforded by ratiometric detection of the β‐lactamase system improved the statistical performance of the assay in comparison with a single‐dye, intensity‐based assay, leading to markedly improved detection for low copy number and rare events. At low levels of gene expression, β‐lactamase was detected with approximately 10‐fold higher confidence than was β‐galactosidase. In rare event detection experiments, cells expressing high levels of β‐lactamase proteins were reliably detected at frequencies of 1:106 compared with about 1:104 for β‐galactosidase.Conclusion:The ratiometric fluorescence readout of the β‐lactamase system based on fluorescence resonance energy transfer allowed more sensitive and accurate detection of gene expression than the currently available β‐galactosidase substrates. Further, the cell‐permeant nature of the substrate improved experimental convenience. These properties facilitated cell engineering and enabled a variety of applications including selection of rare cells from large populations and measurement of low‐expressing or downregulated genes. Cytometry Part A 51A:68–78, 2003. © 2003 Wiley‐Liss, Inc.
Involvement of serotonin mechanisms in the antinociceptive effect of S(+)‐ketoprofen
Authors: Díaz‐Reval Ma. Irene , Ventura‐Martínez Rosa , Déciga‐Campos Myrna , Terrón José A. , Cabré Francesc , López‐Muñoz Francisco J. 
Published: January 2003

AbstractSerotonin (5‐hydroxytryptamine; 5‐HT) plays a role in the modulation and processing of pain and evidence has been provided that some nonsteroidal anti‐inflammatory drugs (NSAIDs) act, at least in part, through this system. The present study was designed to investigate the possible participation of 5‐HT1, 5‐HT2, 5‐HT3, and 5‐HT7 receptor subtypes in the antinociceptive effect of S(+)‐ketoprofen (S‐KP) at spinal and supraspinal level using the “pain induced functional impairment model in rat” (PIFIR model). S‐KP was administered orally (p.o.) and antagonist drugs for 5‐HT receptors (5‐HT1/5‐HT2, and 5‐HT3) were administered intrathecally (i.t.) or intracerebroventricularly (i.c.v.) 15 min before S‐KP. S‐KP (3.4 mg/kg p.o.) produced a significant antinociceptive effect in this model. Pre‐treatment with the 5‐HT1/5‐HT2/5‐HT7 receptor antagonist, methiothepin (1.5 μg, i.c.v.), significantly reversed the antinociceptive effect of S‐KP. In contrast, no significant differences were observed following i.t. administration of methiothepin. Pre‐treatment i.t., but not i.c.v., with the 5‐HT3/5‐HT4 receptor antagonist, tropisetron (0.9 μg), on the other hand, significantly reversed S‐KP‐induced antinociception. These results indicate that serotonin mechanisms are involved in the antinociceptive effect of S‐KP. 5‐HT1/5‐HT2/5‐HT7 receptors participate at the supraspinal level and 5‐HT3/5‐HT4 receptors participate at spinal level. Drug Dev. Res. 57:187–192, 2002. © 2003 Wiley‐Liss, Inc.
Regeneration or scarring: An immunologic perspective
Authors: Harty Mark , Neff Anton W. , King Michael W. , Mescher Anthony L. 
Published: January 2003

AbstractComplete regeneration of complex tissues and organs is usually precluded by fibrotic reactions that lead to scarring. Fish, salamanders, and larval anurans are among the few vertebrates capable of regenerating lost appendages, and this process seems to recapitulate ontogenic development of the structure in most respects. Recent work has revealed a capacity for excellent regeneration in certain mammalian tissues: embryonic or fetal skin and the ear of the MRL mouse. Analyses of these two systems suggest that processes of regenerative growth and patterning for the formation of new structures such as hair follicles may involve modulation of the inflammatory response to the injury in a way that reduces fibrosis and formation of scar tissue. We review evidence that this modulation includes changes in cytokine signaling and may involve properties of the extracellular matrix mediated by factors that include hyaluronic acid and “anti‐adhesive substrates” such as tenascin‐C. New studies and classic work on the capacity for limb regeneration in amphibians are then reviewed, focusing on the loss of this ability in prometamorphic anuran hindlimbs and the view that changing properties of the immune system may also underlie the declining regenerative potential in this system. Finally, we review recent work in comparative and developmental immunology, which raises the possibility that phylogenetic changes in regenerative capacity may be the result of evolutionary changes in cellular activities of the immune system. Developmental Dynamics 226:268–279, 2003.© 2003 Wiley‐Liss, Inc.
Dyslexia and music: measuring musical timing skills
Authors: Overy Katie , Nicolson Roderick I. , Fawcett Angela J. , Clarke Eric F. 
Published: January 2003

AbstractOver the last few decades, a growing amount of research has suggested that dyslexics have particular difficulties with skills involving accurate or rapid timing, including musical timing skills. It has been hypothesised that music training may be able to remediate such timing difficulties, and have a positive effect on fundamental perceptual skills that are important in the development of language and literacy skills (Overy, 2000). In order to explore this hypothesis further, the nature and extent of dyslexics' musical difficulties need to be examined in more detail. In the present study, a collection of musical aptitude tests (MATs) were designed specifically for dyslexic children, in order to distinguish between a variety of musical skills and sub‐skills. 15 dyslexic children (age 7–11, mean age 9.0) and 11 control children (age 7–10, mean age 8.9) were tested on the MATs, and their scores were compared. Results showed that the dyslexic group scored higher than the control group on 3 tests of pitch skills (possibly attributable to slightly greater musical experience), but lower than the control group on 7 out of 9 tests of timing skills. Particular difficulties were noted on one of the tests involving rapid temporal processing, in which a subgroup of 5 of the dyslexic children (33%) (mean age 8.4) was found to account for all the significant error. Also, an interesting correlation was found between spelling ability and the skill of tapping out the rhythm of a song, which both involve the skill of syllable segmentation. These results support suggestions that timing is a difficulty area for dyslexic children, and suggest that rhythm skills and rapid skills may need particular attention in any form of musical training with dyslexics. Copyright © 2003 John Wiley & Sons, Ltd.
The Chemistry of Borylene Complexes
Authors: Braunschweig Holger , Colling Miriam 
Published: January 2003

AbstractOver the past seven years, complexes of various transition metals with bridged or terminal borylene ligands BR have for the first time been reported and fully characterised. Being closely related to important organometallic compounds, such as carbene, vinylidene, and carbonyl complexes, they have already attracted considerable interest both from experimental and computational points of view. Those studies have provided some detailed information about the nature of the metal−boron bond and about the nature of metal and borylene moieties required for the formation of stable complexes. Various methods for their preparation have been developed and the first studies on their reactivity have demonstrated an interesting chemistry. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)