bluuebunny/crossref_metadata_2025_split huggingface dataset:
Left–right asymmetric morphogenesis in the Xenopus digestive system
Authors: Muller Jennifer K. , Prather Deva R. , Nascone‐Yoder Nanette M. 
Published: December 2003

AbstractThe morphogenetic mechanisms by which developing organs become left–right asymmetric entities are unknown. To investigate this issue, we compared the roles of the left and right sides of the Xenopus embryo during the development of anatomic asymmetries in the digestive system. Although both sides contribute equivalently to each of the individual digestive organs, during the initial looping of the primitive gut tube, the left side assumes concave topologies where the right side becomes convex. Of interest, the concave surfaces of the gut tube correlate with expression of the LR gene, Pitx2, and ectopic Pitx2 mRNA induces ectopic concavities in a localized manner. A morphometric comparison of the prospective concave and convex surfaces of the gut tube reveals striking disparities in their rate of elongation but no significant differences in cell proliferation. These results provide insight into the nature of symmetry‐breaking morphogenetic events during left–right asymmetric organ development. Developmental Dynamics 228:672–682, 2003. © 2003 Wiley‐Liss, Inc.
Molecular markers of cardiac endocardial cushion development
Authors: Gitler Aaron D. , Lu Min Min , Jiang Yue Qin , Epstein Jonathan A. , Gruber Peter J. 
Published: December 2003

AbstractEndocardial cushions are precursors of mature heart valves. They form within the looped heart tube as discrete swellings and develop into thin, pliable leaflets that prevent regurgitation of blood. The embryonic origins of cardiac valves include endothelial, myocardial, and neural crest cells. Recently, an increasing number of animal models derived from mutational screens, gene inactivation, and transgenic studies have identified specific molecules required for normal development of the cardiac valves, and critical molecular pathways are beginning to emerge. To further this process, we have sought to assemble a diverse set of molecular markers encompassing all stages of cardiac valve development. Here, we provide a detailed comparative gene expression analysis of thirteen endocardial cushion markers. We identify endocardial cushion expression of the transcription factor Fog1, and we demonstrate active Wnt/β‐catenin signaling in developing endocardial cushions suggesting pathways that have not been previously appreciated to participate in cardiac valve formation. Developmental Dynamics 228:643–650, 2003. © 2003 Wiley‐Liss, Inc.
Function of RARγ and RARα2 at the initiation of retinoid signaling is essential for avian embryo survival and for distinct events in cardiac morphogenesis
Authors: Romeih Mahmoud , Cui Jian , Michaille Jean‐Jacques , Jiang Weihong , Zile Maija H. 
Published: December 2003

AbstractAvian embryogenesis requires retinoid receptor activation by the vitamin A active form, retinoic acid (RA), during neurulation. We conducted loss‐of‐function analysis in quail embryos by nutritional deprivation of RA and by blocking generation of retinoid receptors. Here we identify a distinct role for RARα2 in cardiac inflow tract morphogenesis and for RARγ in cardiac left/right orientation and looping morphogenesis. Blocking normal embryos with antisense oligonucleotides to RARα2 or RXRα diminishes GATA‐4 transcripts, while blocking RARγ or RXRα diminishes nodal and Pitx2 transcripts; the expression of these genes in the heart forming region resembles that of the vitamin A‐deficient embryo. Blocking the function of RARγ, RARα2, and RXRα recapitulates the complete vitamin A‐deficient phenotype. RARγ is the most potent mediator of the retinoid signal at this time of development. Our studies provide strong evidence that critical RA‐requiring developmental events in the early avian embryo are regulated by means of distinct retinoid receptor signaling pathways. Developmental Dynamics 228:697–708, 2003. © 2003 Wiley‐Liss, Inc.
Generation of structures formed by lens and retinal cells differentiating from embryonic stem cells
Authors: Hirano Mariko , Yamamoto Akitsugu , Yoshimura Naoko , Tokunaga Tomoyuki , Motohashi Tsutomu , Ishizaki Katsuhiko , Yoshida Hisahiro , Okazaki Kenji , Yamazaki Hidetoshi , Hayashi Shin‐Ichi , Kunisada Takahiro 
Published: December 2003

AbstractEmbryonic stem cells have the potential to give rise to all cell lineages when introduced into the early embryo. They also give rise to a limited number of different cell types in vitro in specialized culture systems. In this study, we established a culture system in which a structure consisting of lens, neural retina, and pigmented retina was efficiently induced from embryonic stem cells. Refractile cell masses containing lens and neural retina were surrounded by retinal pigment epithelium layers and, thus, designated as eye‐like structures. Developmental processes required for eye development appear to proceed in this culture system, because the formation of the eye‐like structures depended on the expression of Pax6, a key transcription factor for eye development. The present culture system opens up the possibility of examining early stages of eye development and also of producing cells for use in cellular therapy for various diseases of the eye. Developmental Dynamics 228:664–671, 2003. © 2003 Wiley‐Liss, Inc.
Synthesis, Structure and Magnetic Properties of the Cobalt(II) 1,1′‐Biphenyl‐2,2′‐dicarboxylate Hydroxide Chain Compound [Co3{O2CC12H8CO2}2.5(OH)(H2O)2]n
Authors: Rueff Jean‐Michel , Pillet Sébastien , Bonaventure Gautier , Souhassou Mohamed , Rabu Pierre 
Published: December 2003

AbstractA new 1D compound [Co3(O2CC12H8CO2)2.5(OH)(H2O)2] (2) was synthesised with the hydrothermal method from Co(NO3)2·6H2O, 1,1′‐biphenyl‐2,2′‐dicarboxylic acid, and KOH under hydrothermal conditions. Its structure was solved by single‐crystal X‐ray diffraction analysis. Compound 2 crystallises as purple crystals with the monoclinic cell (C2/c) a = 19.370(1), b = 14.5350(9), c = 22.583(1) Å, β = 89.910(4)°. The structure consists of chains of butterfly motifs of CoII ions in both octahedral and tetrahedral oxygen sites. The structural, IR and UV spectroscopic data and magnetic behaviour are presented and compared to that of the parent pink compound 1, obtained under slightly different stoichiometric conditions. Ligand‐field characteristics, Dq ≈︁ 1146 cm−1 and B ≈︁ 811 cm−1 for the octahedral sites, and Dq ≈︁ 434 cm−1 and B ≈︁ 782 cm−1 for CoII in the tetrahedral sites, were deduced from the electronic spectra and related to the structural and magnetic findings. From the magnetic point of view, the occurrence of efficient Co−O−Co superexchange pathways contributes to significant antiferromagnetic coupling between the cobalt(II) ions along the chains. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Bent and Linear Forms of the (μ‐Oxo)bis[trichloroferrate(III)] Dianion: An Intermolecular Effect − Structural, Electronic and Magnetic Properties
Authors: Lledós Agustí , Moreno‐Mañas Marcial , Sodupe Mariona , Vallribera Adelina , Mata Ignasi , Martínez Benjamín , Molins Elies 
Published: December 2003

AbstractWe have analyzed the great diversity of Fe−O−Fe angles, 140−180°, found in the X‐ray structures of the (μ‐oxo)bis[trichloroferrate(III)] dianion [Cl3FeOFeCl3]2− from both experimental and theoretical points of view. Theoretical calculations show that only the linear isomer is found as a minimum on the potential energy surface. Detailed analysis of the crystal packing indicates that the angular form is due to attractive intermolecular interactions. Analysis of a selected reduced set of the 45 crystal structures retrieved from the Cambridge Structural Database allowed us to classify the bending of the [Cl3FeOFeCl3]2− dianion in three categories, depending on the balance and strength of the intermolecular O···H−X contacts. A crystal diffraction study on the bis(benzyltrimethylammonium) salt has shown both bent (144.6°) and linear (180°) forms of the (μ‐oxo)bis[trichloroferrate(III)] dianion. The magnetic susceptibility of this compound has been fitted by assuming two equally weighted contributions (Jang and Jlin) of the two forms, considering Jang − Jlin estimated by theoretical calculations. The obtained Jang and Jlin of −117 and −133 cm−1 respectively, agree well with B3LYP results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ab initio Study on Luminescence and Aurophilicity of a Dinuclear [(AuPH3)2(i‐mnt)] Complex (i‐mnt = isomer‐Malononitriledithiolate)
Authors: Pan Qing‐Jiang , Zhang Hong‐Xing 
Published: December 2003

AbstractThe luminescence and Au−Au aurophilicity of the model complex, [(AuPH3)2(i‐mnt)] (i‐mnt = isomer‐malononitriledithiolate in both solid state and solution have been studied by ab initio methods. The structures of the AuI complex were fully optimized by the MP2 method for the ground state and the CIS method for the excited state. The b3A′ excited‐state Au−Au (2.946 Å) and the corresponding Au−Au stretching frequency (83 cm−1) indicate intramolecular Au−Au aurophilicity. Using [(AuPH3)2(i‐mnt)]2 to rationalize the solid‐state emission to the [(AuPPh3)2(i‐mnt)] complex at 20 K we assigned the experimental emission (462 nm) to an Au−Au⇄i‐mnt charge‐transfer (3MMLCT) transition from the triplet excited state to the ground state. In the 3MMLCT emissive excited state, the Au−Au aurophilicity, including intra‐ and intermolecular Au−Au interactions, results in a ca. 120 nm red shift in emission relative to that of mononuclear PH3AuSH. The calculated absorption and emission in dichloromethane solution agree with the experimental results. These results, combined with our previous studies on both [Au2(dpm)2]2+ [dpm = bis(diphosphanyl)methane] and [Au2(dpm)(i‐mnt)], indicate a clear correlation between Au−Au aurophilicity and the excited‐state properties of the dinuclear AuI complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Recent progress in pharmacokinetic applications of capillary electrophoresis
Authors: Lin Chun‐Che , Li Yu‐Ting , Chen Shu‐Hui 
Published: December 2003

AbstractThis review is a continuation of the previous reviews (Electrophoresis1999,20, 3259–3268;Electrophoresis2001,22, 4244–4248) to update the recent publications from 2001 to 2003 on pharmacokinetic studies using capillary electrophoresis (CE). During this period of time, CE remains as a unique analytical method for some studies, which would otherwise be limited by many factors, such as the sample volume, detection sensitivity, or separation power. It is particularly noticeable that the separation of chiral drugs in biological sample and the use of solid‐phase extraction (SPE) as a simple and convenient means of sample preparation appear to become popular for CE‐based assays. The use of CE for assessing complete pharmacokinetic information, however, did not show a significant growth during this period of time. In order to provide a broad range of view on how biological samples are analyzed by CE, this review will cover publications during the past two years on the use of CE for the analysis of drugs in biological fluids for general pharmacokinetic applications including drug monitoring and bioavailability studies.
Recent applications of microemulsion electrokinetic chromatography
Authors: Hansen Steen Honoré 
Published: December 2003

AbstractMicroemulsions are used in a similar way as micellar solutions are used for separations in capillary electrophoresis. Within the last ∼ six years, a number of papers have appeared in the literature in which the separation characteristics of microemulsion electrokinetic chromatography (MEEKC) have been investigated. The total number of papers dealing with MEEKC is now close to 100. One of the major fields of application for MEEKC has been the characterization of the lipophilicity of chemical substances but the technique has also been applied for the analysis of substances within the fields of natural products, pharmaceuticals, vitamins, peptides, proteins, and nucleic acid bases as well as nucleosides. An overview of the applications is given together with the microemulsions used for each application.
Recent applications of capillary isoelectric focusing
Authors: Kilár Ferenc 
Published: December 2003

AbstractAfter the advent of capillary isoelectric focusing (CIEF) in the 80's several approaches have been developed in order to use the technique in routine analyses. The recent years showed an extensive increase in the applications of this technique employing its exceptionally high‐resolution power. Methodological improvements, as well as hyphenation with other electrophoretic and chromatographic separation procedures, proved the versatility of CIEF in studies of clinically important proteins, recombinant product, cell lysates and other complex mixtures. The combination of CIEF with mass spectrometry detection is one of the major challenges for studying proteomics. This review collected the recent applications of CIEF including innovations in the experimental setup, remedies for the presence of salts in samples, calibration of the pH gradient, carrier ampholyte‐free isoelectric focusing, the progress in micropreparation, two‐dimensional separations, etc.
Recent advances in enantioseparations of peptides by capillary electrophoresis
Authors: Scriba Gerhard K. E. 
Published: December 2003

AbstractThe present review summarizes peptide enantioseparations by capillary electrophoresis with the focus on recent developments. These include the application of new chiral selectors and systematic studies involving series of di‐ and tripeptides with either common features or with a variety of structures. One section emphasizes mechanistic aspects of the migration order of the enantiomers in cyclodextrin‐assisted chiral separations with respect to the complexation constants and the mobilities of the transient diastereomeric complexes. In addition, short paragraphs on the application of chiral capillary electrophoresis to the determination of the stereochemical purity of peptidomimetics and on chiral separations of peptides by capillary electrochromatography have also been included.
Capillary electrophoresis – mass spectrometry: 15 years of developments and applications
Authors: Schmitt‐Kopplin Philippe , Frommberger Moritz 
Published: December 2003

AbstractSince its introduction in 1987, capillary electrophoresis‐mass spectrometry (CE‐MS) has developed to a well accepted multidimensional analytical approach complementary and/or competitive to classical MS‐hyphenated separation techniques. The threefold combination of rapid developments of an exceptional separation technique, of selective mass detection possibilities, and of very mild ionization modes first allowed these progresses. This article shows the CE specificities that need to be well controlled/known, compared to classical and more routinely used liquid chromatography in the light of its coupling to MS. The major trends and developments over the last 15 years and most of the reviews and applications found in ISI Web of science and publisher databases are presented in a tabulated way. The reader can thus rapidly find existing CE‐MS analysis techniques in his field of research and application (forensics, environment, bioanalytics, pharmaceutics, and metabolites).
Molecularly imprinted polymers in capillary electrochromatography: Recent developments and future trends
Authors: Spégel Peter , Schweitz Leif , Nilsson Staffan 
Published: December 2003

AbstractThe developments in molecularly imprinted polymer (MIP)‐based capillary electrochromatography (CEC) achieved during the past years are reviewed in this article. The MIP is prepared using a templated polymerization reaction and results in a material with a high selectivity towards a predetermined target. The selectivity of the MIP is comparable to that of the biological antibodies, however, the MIP is much more stable and is thus able to withstand extremely harsh conditions in terms of pH, temperature, and organic solvents. The high selectivity and stability of the MIP made it an interesting candidate for application as stationary phase sorbent in chromatography. However, due to slow kinetics the efficiency of the early MIP columns, which were predominantly applied in high‐performance liquid chromatography (HPLC), were limited. The use of CEC was thought to improve the efficiency of the MIP‐based separation system. The small dimensions of the capillary format employed in CEC have put demands on the polymer systems which have resulted in the development of many different polymer formats. Thus, this need for novel MIP formats for applications in CEC has contributed a lot to the general development of MIP formats as well as to the knowledge in MIP synthesis and characteristics.
Recent advances in amino acid analysis by capillary electrophoresis
Authors: Poinsot Véréna , Bayle Christophe , Couderc François 
Published: December 2003

AbstractAmino acids are studied extensively using capillary electrophoresis. In a previous article, we reviewed applications reported in the period 1999 – early 2001 (Prata, C., Bonnafous, P., Fraysse, N., Treilhou, M., Poinsot, V., Couderc, F., Electrophoresis 2001, 22, 4129–4138). In this article we follow on with this review for the period end of 2001 – beginning of 2003. We will report the developments of detection methods, separations of enantiomers, the new medical applications, and amino acids in food and plants. This review shows that CE is more and more important for the amino acid analysis.
Particles from fires—a screening of common materials found in buildings
Authors: Hertzberg Tommy , Blomqvist Per 
Published: December 2003

AbstractSmall combustion generated particles are known to have a negative impact on human health and on the environment. In spite of the huge amount of particles generated locally in a fire accident, few investigations have been made on the particles from such fires. In this article, 24 different materials or products, typically found in buildings have been exposed to burning conditions in order to examine their particle generating capacity. In addition, a carbon fibre based composite material was tested in order to investigate if asbestos‐resembling particles could be generated in a fire situation.The majority of the experiments were performed in the small‐scale cone calorimeter, and some further data were collected in intermediate scale (SBI) and full scale (room‐corner) tests. Additional testing of the composite material was made in a small‐scale tubular reactor.The amount of particles and particle size distributions were measured by the use of a low‐pressure impactor and particle aerodynamic diameter sizes from 30 nm to 10 μm were measured.The results from the project show that the yield of particles generated varied significantly between materials but that the shape of mass and number size distributions were very similar for all the materials tested. The maximum amount of particles was obtained from materials that did not burn well (e.g. flame retarded materials). Well‐burning materials, e.g. wood materials, tend to oxidize all available substances and thereby minimize the amount of particles in the smoke gas. It was found that asbestos‐resembling particles could be produced from under‐ventilated combustion of the composite material tested. Copyright © 2003 John Wiley & Sons, Ltd.
Flutter instability prediction techniques for bridge deck sections
Authors: Robertson I. , Sherwin S. J. , Bearman P. W. 
Published: December 2003

AbstractIn order to investigate the fluid/structure interaction of a bridge deck in a cross wind, a two‐dimensional hp/Spectral fluid solver has been modified to incorporate a body undergoing translational and rotational motion. A moving frame of reference is attached to the body to utilize the efficiency of a fixed mesh solver. The critical reduced velocity at which a bridge deck undergoes a two degree of freedom flutter instability is then predicted using various methods: a theoretical linear potential model; quasi‐steady theory; a linear evaluation of applied forces using prescribed motion; and free translational and rotational motion of the structure. These predictions are compared with experimental data and the various merits of each scheme are reported. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of calcium ions on the solubility of muscular collagen and tenderness of beef meat
Authors: Ostoja Halina , Cierach Marek 
Published: December 2003

AbstractThe aim of the present study was to determine the effect of aqueous solutions of calcium chloride and calcium lactate on the solubility of beef collagen in raw and cooked meat. The content of total collagen, water‐ and acetic acid‐soluble collagen and insoluble collagen was determined in beef samples. Shearing force was measured after heat treatment. It was found that calcium ions had no significant effect on the solubility of muscular collagen. An improvement in beef tenderness (27%–34%) caused by calcium ions did not result from breaking of the native structure of muscular collagen.
Fluorometric determination of chemically available lysine: Adaptation, validation and application to different milk products
Authors: Ferrer E. , Alegría A. , Farré Rosaura , Abellán P. , Romero F. 
Published: December 2003

AbstractA spectrophotometric method based on the reaction between available lysine and ortho‐phthaldialdehyde (OPA) was adapted and validated for fluorometric determination of the chemically available lysine contents in milk matrices (UHT and conventional in‐bottle sterilized cow milk, milk‐based infant formulas and infant formula ingredients). The values of the analytical parameters show its usefulness as a routine method (linearity, r = 0.9992; detection limit, 0.0066 mg/mL assay; accuracy, 99–108%; precision, intra‐day 2.1–5.9% and inter‐day 3.5–10.2%). No statistically significant differences (p < 0.05) were found between the values obtained with the adapted method and those obtained applying the 1‐fluoro‐2,4‐dinitrobenzene (FDNB) (Carpenter) technique. The OPA method was used to measure the chemically available lysine contents in UHT and sterilized milk marketed in Spain, to study the evolution of chemically available lysine during the shelf‐life of UHT milks, and finally the quality of name‐ and store‐brand UHT milks was also compared. No statistically significant differences (p < 0.05) were found between either the available lysine contents of the same type of UHT or sterilized milk or between store‐ and name‐brand UHT milks. Statistically significant differences (p < 0.05) were found between the chemically available lysine contents in UHT and sterilized milk. Losses of chemically available lysine ranging from 2.7 to 29% were obtained during the shelf‐life of UHT milk.
Quality of cold‐pressed edible rapeseed oil in Germany
Authors: Matthäus Bertrand , Brühl Ludger 
Published: December 2003

AbstractForty‐eight cold‐pressed edible rapeseed oils obtained from small‐ and medium‐sized decentralized plants located all over Germany were characterized by different chemical parameters for their composition and by descriptive sensory evaluation. Between the different oils great differences could be noticed for each parameter. The results evidenced that additionally to the features given in the Guidelines for edible fats and oils of the German Food Codex, especially the sensory evaluation, the oxidation stability (Rancimat), content and the composition of tocopherols, the content of trans‐fatty acids and the content of steradienes were crucial parameters to guarantee a high‐quality product for the consumer.