bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex Morphology of Melt‐Spun Nylon‐6 Fibres Investigated by1H Double‐Quantum‐Filtered NMR Spin‐Diffusion Experiments
Authors: Buda A. , Demco D. E. , Blümich B. , Litvinov V. M. , Penning J. P. 
Published: June 2004

AbstractThe complex morphology of high‐speed melt‐spun nylon‐6 fibres hydrated with D2O was investigated using1H double‐quantum‐filtered spin‐diffusion NMR experiments. The magnetisation exchange from selected crystalline domains along the fibrils and interfibrils was simulated with the help of a three‐dimensional solution of a spin‐diffusion equation approximated by a product of one‐dimensional analytical NMR signals, which correspond to a lamellar morphology. This allows to measure the sizes of crystalline and less‐mobile amorphous domains along the fibrils, as well as the diameter of the fibrils and interfibril distances. A series of nylon‐6 fibres with extreme values of winding speed and draw ratio was investigated. The changes detected in the domain size along the fibrils and interfibrils show the same trend in the data obtained from wide‐angle X‐ray diffraction and small‐angle X‐ray scattering.
Principles of Spin‐Echo Modulation by J‐Couplings in Magic‐Angle‐Spinning Solid‐State NMR
Authors: Duma Luminita , Lai Wai Cheu , Carravetta Marina , Emsley Lyndon , Brown Steven P. , Levitt Malcolm H. 
Published: June 2004

AbstractIn magic‐angle‐spinning solid‐state NMR, the homonuclear J‐couplings between pairs of spin‐1/2 nuclei may be determined by studying the modulation of the spin echo induced by a π‐pulse, as a function of the echo duration. We present the theory of J‐induced spin‐echo modulation in magic‐angle‐spinning solids, and derive a set of modulation regimes which apply under different experimental conditions. In most cases, the dominant spin‐echo modulation frequency is exactly equal to the J‐coupling. Somewhat surprisingly, the chemical shift anisotropies and dipole–dipole couplings tend to stabilise—rather than obscure—the J‐modulation. The theoretical conclusions are supported by numerical simulations and experimental results obtained for three representative samples containing 13C spin pairs.
High‐Performance Selective Excitation Pulses for Solid‐ and Liquid‐State NMR Spectroscopy
Authors: Veshtort Mikhail , Griffin Robert G. 
Published: June 2004

AbstractComputer‐optimized selective pulses are routinely used in solution‐state NMR spectroscopy. At the same time, their utility and importance for solid‐state applications has yet to be fully realized. We suggest a new computational approach that makes the design of soft selective pulses with desired properties relatively straightforward. By applying this technique to the generic selective excitation problem, we have arrived at a family of high performance selective excitation pulses, dubbed E‐Family, that allows more flexibility and better performance than analogous pulses previously reported in the literature. The new pulses have been successfully tested in both solid‐ and solution‐state NMR experiments. A theoretical treatment of the effects of chemical shift anisotropy (CSA) on the selective excitation in magic‐angle spinning (MAS) experiments in solids is presented. The set of heuristics that comprise our new strategy were incorporated into a general NMR simulation program SPINEVOLUTION.
Immunophenotypic differentiation patterns of normal hematopoiesis in human bone marrow: Reference patterns for age‐related changes and disease‐induced shifts
Authors: van Lochem E.G. , van der Velden V.H.J. , Wind H.K. , te Marvelde J.G. , Westerdaal N.A.C. , van Dongen J.J.M. 
Published: June 2004

AbstractBackgroundThe abundance of monoclonal antibodies (mAb) and the routine use of quadruple stainings in flow cytometry allow stepwise analysis of bone marrow (BM) samples that are suspected for abnormal hematopoiesis. A screening phase that precedes lineage‐specific classification phases should be sufficient to assess whether the BM has a normal or abnormal composition, as well as to identify the abnormal differentiation lineage.MethodsFor a quick and easy flow cytometric screening of BM samples, we selected six quadruple immunostainings that cover multiple differentiation stages of the B‐cell, monocytic, granulocytic, and erythroid lineages: TdT/CD20/CD19/CD10 and CD45/CD34/CD19/CD22 for B cells, CD34/CD117/CD45/CD13.33 for precursor granulocytic and precursor monocytic cells (myelo/monoblasts), CD14/CD33/CD45/CD34 for monocytic cells, CD16/CD13/CD45/CD11b for granulocytic cells, and CD71/CD235a/CD45/CD117 for erythroid cells.ResultsThe six quadruple immunostainings reveal specific staining patterns in normal BM, which allow the recognition of various subpopulations of the respective lineages. These staining patterns can be used as a frame of reference for recognition of normal and abnormal BM development. Examples of normal (age‐related) variations in these otherwise stable staining patterns are presented together with several abnormal differentiation patterns.ConclusionsAlthough alternative immunostainings can be used (e.g., including NK‐ and T‐cell markers), we feel that the selected six stainings represent a comprehensive and easy screening phase for quick identification of shifts in the composition of the studied differentiation lineages, reflecting age‐related changes or disease‐induced BM abnormalities. © 2004 Wiley‐Liss, Inc.
Diabetes: insulin resistance and derangements in lipid metabolism. Cure through intervention in fat transport and storage
Authors: Raz Itamar , Eldor Roi , Cernea Simona , Shafrir Eleazar 
Published: June 2004

AbstractWe present multiple findings on derangements in lipid metabolism in type 2 diabetes. The increase in the intracellular deposition of triglycerides (TG) in muscles, liver and pancreas in subjects prone to diabetes is well documented and demonstrated to attenuate glucose metabolism by interfering with insulin signaling and insulin secretion. The obesity often associated with type 2 diabetes is mainly central, resulting in the overload of abdominal adipocytes with TG and reducing fat depot capacity to protect other tissues from utilizing a large proportion of dietary fat. In contrast to subcutaneous adipocytes, the central adipocytes exhibit a high rate of basal lipolysis and are highly sensitive to fat mobilizing hormones, but respond poorly to lipolysis restraining insulin. The enlarged visceral adipocytes are flooding the portal circulation with free fatty acids (FFA) at metabolically inappropriate time, when FFA should be oxidized, thus exposing nonadipose tissues to fat excess. This leads to ectopic TG accumulation in muscles, liver and pancreatic beta‐cells, resulting in insulin resistance and beta‐cell dysfunction. This situation, based on a large number of observations in humans and experimental animals, confirms that peripheral adipose tissue is closely regulated, performing a vital role of buffering fluxes of FFA in the circulation. The central adipose tissues tend to upset this balance by releasing large amounts of FFA. To reduce the excessive fat outflow from the abdominal depots and prevent the ectopic fat deposition it is important to decrease the volume of central fat stores or increase the peripheral fat stores. One possibility is to downregulate the activity of lipoprotein lipase, which is overexpressed in abdominal relatively to subcutaneous fat stores. This can be achieved by gastrointestinal bypass or gastroplasty, which decrease dietary fat absorption, or by direct means that include surgical removal of mesenteric fat. Indirect treatment consists of the compliant application of drastic lifestyle change comprising both diet and exercise and pharmacotherapy that reduces mesenteric fat mass and activity. The first step should be an attempt to effectively induce a lifestyle change. Next comes pharmacotherapy including acarbose, metformin, PPARγ, or PPARγα agonists, statins and orlistat, estrogens in postmenopausal women or testosterone in men. Among surgical procedures, gastric bypass has been proven to produce beneficial results in advance of other surgical techniques, the evidence basis of which still needs strengthening. Copyright © 2004 John Wiley & Sons, Ltd.
Neonatal tolerance revisited again: specific CTL priming in mouse neonates exposed to small numbers of semi‐ or fully allogeneic spleen cells
Authors: Adkins Becky , Jones Monica , Bu Yurong , Levy Robert B. 
Published: June 2004

AbstractNeonatal and adult mice mount distinct responses to allogeneic cells. Injection of neonates with fully allogeneic cells results in lethal graft‐vs.‐host disease (GVHD), whereas injection of semi‐allogeneic (F1) cells leads to lifelong tolerance to the alloantigens, often marked by specific CTL non‐responsiveness. In contrast, adults injected with the same number of either cell type become primed and develop vigorous anti‐donor CTL activity. One possibility for this differential responsiveness may be developmental immaturity in the CTL arm of the immune system. Recent studies have shown that neonates are capable of mounting mature CTL responses, but only in the presence of strong Th1‐promoting agents. Here, we demonstrate that neonates are competent to develop vigorous MHC class I‐restricted CTL activity in vivo upon exposure to either fully or semi‐allogeneic spleen cells. Specific CTL activity was generated using doses of cells approximately tenfold lower than levels used for the induction of GVHD or tolerance. Thus, the present studies demonstrate that mouse neonates are fully mature in their capacity to develop alloreactive CTL activity, as long as the dose of donor cells is low enough. These results have important implications for the known exposure of human fetuses and infants to small numbers of maternal cells.
The SH3 domain of Tec kinase is essential for its targeting to activated CD28 costimulatory molecule
Authors: Garçon Fabien , Ghiotto Marguerite , Gérard Audrey , Yang Wen‐Chin , Olive Daniel , Nunès Jacques A. 
Published: June 2004

AbstractThe Tec family of protein tyrosine kinases plays an important role in T cell signaling. Tec, the prototypical member of this kinase family, can interact with CD28, which is a costimulatory molecule. However, the regulation of Tec upon CD28 stimulation remains poorly understood. Here we show that CD28–B7‐mediated interactions are likely involved in the relocalization of Tec at the contactzone between T cells and APC. Upon CD28 ligation with specific antibodies or natural ligands, Tec translocates to the plasma membrane where it colocalizes with the CD28 molecule. The Src‐homology 3(SH3) domain of Tec and the two proline‐rich motifs of CD28 are involved in this process. Furthermore, we show that CD28 signaling requires the SH3 domain of Tec as well as proline residues presentin the intracytoplasmic tail of CD28. These results should provide new insights into the complex regulation of Tec kinases in T cells.
Naked RNA vaccine controls tumors with down‐regulated MHC class I expression through NK cells and perforin‐dependent pathways
Authors: Cheng Wen‐Fang , Hung Chien‐Fu , Lee Chien‐Nan , Su Yi‐Ning , Chang Ming‐Cheng , He Liangmei , Wu T.‐C. , Chen Chi‐An , Hsieh Chang‐Yao 
Published: June 2004

AbstractOne of the major issues facing cancer immunotherapy is that many human cancers down‐regulate expression of MHC class I molecules. The understanding of the mechanisms of antitumor effects against tumors with down‐regulated MHC class I will facilitate rational design of vaccines and immunotherapeutic strategies to control such tumors. A naked Sindbis RNA replicon vector (SINrep5) encoding the herpes simplex virus type 1 protein VP22 linked to E7 (SINrep5‐VP22/E7) generated significant antitumor effects against TC‐1 and TC‐1 P3(A15), tumors with down‐regulated MHC class I expression. Naked SINrep5 RNA without the insert or an E7 vaccine also produced antitumor effects against TC‐1 P3(A15) but not TC‐1. Mice vaccinated with any of these naked RNA vaccines generated higher percentages of NK cells. In vivo Ab depletion experiments revealed that NK cells were important for the antitumor effects of naked RNA vaccines against TC‐1 P3(A15) and that the antitumor effects were perforin‐dependent. Poly I:C also increased the percentage of NK cells and generated antitumor effects against the tumors with down‐regulated MHC class I. Thus, the SINrep5‐VP22/E7 naked RNA vaccinecontrols MHC class I‐positive and MHC class I‐down‐regulated tumor cells via different mechanisms, and NK cells play an important role in the antitumor effects generated by naked RNA replicon vaccines.
Prenatal development of the porcine TCR δ repertoire: dominant expression of an invariant T cell receptor Vδ3‐Jδ3 chain
Authors: Holtmeier Wolfgang , Geisel Wiebke , Bernert Kerstin , Butler John E. , Šinkora Marek , Řeháková Zuzana , Šinkora Jiři , Caspary Wolfgang F. 
Published: June 2004

AbstractThe prenatal development of the porcine γ/δ TCR repertoire was studied by complementarity‐determining region 3 (CDR3) spectratyping and sequencing of TRDV1–DV5 transcripts. Specimens from the small and large intestine, spleen, thymus, liver, bone marrow and PBMC from fetal piglets between 38 and 114 days of gestation (DG) were examined. The TCR δ repertoire was highly restricted early in gestation (DG38–DG57) and an invariant TRDV3 transcript, lacking the N/D region, was found in different fetuses throughout gestation and dominated the TRDV3 repertoires of all organs atmid gestation (∼DG55). Near the end of gestation, this invariant TRDV3 transcript was absent from the thymus but was still present, in a less dominant manner, in the intestine and spleen. The average CDR3 length of all Vδ subgroups increased with ontogeny, suggesting an increase in activity of TdT. Thus, the persistence of fetal γ/δ T cells expressing an invariant TRDV3 chain throughout development is especially surprising since TdT is active early in gestation in swine. We speculate that these γ/δ T cells might have been selectively expanded by (self)‐ligands and may have an important function throughout fetal development.
Hydroformylation of 1,5‐Hexadiene Catalyzed by Rhodium Complexes in Supercritical Carbon Dioxide and in Toluene: Effects of Fluorinated Phosphane Ligands and Reaction Conditions
Authors: Fujita Shin‐ichiro , Fujisawa Shinya , Bhanage Bhalchandra M. , Ikushima Yutaka , Arai Masahiko 
Published: June 2004

AbstractRhodium‐catalyzed hydroformylation of 1,5‐hexadiene to dialdehydes was investigated in compressed CO2 and in toluene using different fluorinated phosphane compounds as ligands at a temperature of 60 °C. Product yields depend greatly on the ligand used and, of the ligands examined, tris[3,5‐bis(trifluoromethyl)phenyl]phosphane is the most effective for the production of dialdehydes both in supercritical CO2 (scCO2) and in toluene. The total yield of the dialdehydes passes through a minimum at about 9 MPa as the CO2 pressure is increased and increases appreciably as the H2 pressure in scCO2 increases. The effect of the syngas (H2/CO) and H2 pressures on the reaction in scCO2 is different from that in toluene. It has been suggested that scCO2 promotes the hydroformylation reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Two Branched Fluorescent Receptors and Their Binding Properties for Dicarboxylate Anions
Authors: Zeng Zhen‐Ya , He Yong‐Bing , Wu Jin‐Long , Wei Lan‐Hua , Liu Xin , Meng Ling‐Zhi , Yang Xi 
Published: June 2004

AbstractTwo multi‐armed neutral fluorescent anion receptors (1, 2) bearing multiple amide and thiourea binding sites were synthesized. Study of their UV/Vis and fluorescence spectra indicates that receptors 1 and 2 both form 1:1 complexes with dicarboxylate anions, and that the sensitivity for recognition of dicarboxylate is related to the chain lengths of these dicarboxylate anions. Upon addition of anions, the fluorescence intensities of host solutions were changed significantly. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Heck Coupling Reaction Using Aryl Vinyl Ketones: Synthesis of Flavonoids
Authors: Bianco Armandodoriano , Cavarischia Claudia , Guiso Marcella 
Published: June 2004

AbstractIn our previous communication, an α,β‐unsaturated aryl ketone was employed as the substrate olefin, which underwent arylation in the Heck coupling reaction. The use of this reagent has allowed us to design a new strategy for the synthesis of flavonoids. In this paper, we illustrate the versatility of the procedure, which was used for the preparation of several chalcones. According to our synthetic scheme, several aryl iodides, selected in order to obtain chalcones differently substituted in ring B, were treated with α,β‐unsaturated ketones. All reported syntheses gave high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Access to Any Site‐Directed Isotopomer of Methionine, Selenomethionine, Cysteine, and Selenocysteine − Use of Simple, Efficient Modular Synthetic Reaction Schemes for Isotope Incorporation
Authors: Siebum Arjan H. G. , Woo Wei Sein , Raap Jan , Lugtenburg Johan 
Published: June 2004

AbstractSimple modular reaction schemes that allow access to any isotopomer of protected serine and homoserine have been worked out. These systems could be simply converted into cysteine, selenocysteine, homocysteine, homoselenocysteine, the essential amino acid methionine, and selenomethionine by Mitsunobu chemistry. These sulfur‐ and selenium‐containing amino acids fulfil many essential roles in the living organism. In addition, homoserine could be converted in a few steps into optically active L‐vinylglycine. As well as the stable isotopes 13C, 15N, 17O, and 18O, the radioactive isotopes of sulfur, selenium and carbon can also be easily introduced in a site‐directed fashion. In view of the wide scope of the Mitsunobu reaction, we feel that many more important systems with the carbon skeleton of serine and homoserine should be preparable through this basic chemistry in any site‐directed isotopically labeled form. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Solid‐Phase Synthesis of Complex Oligosaccharides Using Azidoglucose as a Glycosyl Acceptor
Authors: Wu Xiangyang , Schmidt Richard R. 
Published: June 2004

AbstractThe solid phase synthesis of oligosaccharides 1−3 was performed on Merrifield resin. These syntheses are based on the hydroxymethylbenzyl benzoate spacer‐linker system and, for regioselective chain extension, the use of O‐glycosyl trichloroacetimidates as glycosyl donors containing temporary O‐Fmoc protection. The important lactosamine‐containing oligosaccharides 1−3 are accessible in excellent yields by using a 2‐azidoglucose residue as the glucosamine building block adjacent to the spacer‐linker system. Only standard amounts of the glycosyl donor are employed in this solid phase oligosaccharide synthesis and we did not have to resort to any capping procedures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Dihaloadamantanes: Ring Closure versus Rearrangement or Halogen‐Displacement Reactions
Authors: Mlinarić‐Majerski Kata , Veljković Jelena , Kaselj Mira , Marchand Alan P. 
Published: June 2004

AbstractThree dihaloadamantanes [i.e., 2‐bromo‐1‐(chloromethyl)adamantane (1), 1‐(bromomethyl)‐2‐chloroadamantane (2) and 2‐bromo‐1‐(bromomethyl)adamantane (3)] were synthesized, and their corresponding ring‐closing reactions, performed by using Na metal or alkyllithium reagents, were studied. Compound 1 reacted with Na in toluene or in tetraglyme to afford 1,2‐methanoadamantane (4) as the major product. However, the corresponding reactions, when performed by using 2 and 3 as substrates, produced methyladamantane (5) or 4‐methyleneprotoadamantane (6) as the major reaction products. The corresponding reactions of 1 and 2 with tBuLi or nBuLi afforded small quantities of 4, 5 and 6 along with the corresponding monohalides, that is, 1‐(chloromethyl)adamantane (7) and 2‐chloro‐1‐methyladamantane (8), which constituted the major products of these reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Fast Access to Non‐Symmetrically Substituted 1,3‐Alternate Conformers of Calix[4]arenes
Authors: Kleij Arjan W. , Prados Pilar , de Mendoza Javier 
Published: June 2004

AbstractA simple and direct protocol is reported for the synthesis of the first non‐symmetrically substituted 1,3‐alternate conformers of calix[4]arenes by selective mono‐deacylation of a tribenzoyl precursor under basic conditions, followed by dialkylation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Equivalent viscous damping for modeling inelastic impacts in earthquake pounding problems
Authors: Anagnostopoulos Stavros A. 
Published: June 2004

AbstractIn studies of earthquake‐induced pounding between adjacent structures, spring–dashpot elements are often used to simulate the impacts. In this brief paper an equation is derived expressing the dashpot constant as a function of the coefficient of restitution, in terms of which inelastic impacts of colliding simple bodies have usually been described. Copyright © 2004 John Wiley & Sons, Ltd.
A modal pushover analysis procedure to estimate seismic demands for unsymmetric‐plan buildings
Authors: Chopra Anil K. , Goel Rakesh K. 
Published: June 2004

Abstract An Erratum has been published for this article in Earthquake Engng. Struct. Dyn. 2004; 33:1429. Based on structural dynamics theory, the modal pushover analysis (MPA) procedure retains the conceptual simplicity of current procedures with invariant force distribution, now common in structural engineering practice. The MPA procedure for estimating seismic demands is extended to unsymmetric‐plan buildings. In the MPA procedure, the seismic demand due to individual terms in the modal expansion of the effective earthquake forces is determined by non‐linear static analysis using the inertia force distribution for each mode, which for unsymmetric buildings includes two lateral forces and torque at each floor level. These ‘modal’ demands due to the first few terms of the modal expansion are then combined by the CQC rule to obtain an estimate of the total seismic demand for inelastic systems. When applied to elastic systems, the MPA procedure is equivalent to standard response spectrum analysis (RSA). The MPA estimates of seismic demand for torsionally‐stiff and torsionally‐flexible unsymmetric systems are shown to be similarly accurate as they are for the symmetric building; however, the results deteriorate for a torsionally‐similarly‐stiff unsymmetric‐plan system and the ground motion considered because (a) elastic modes are strongly coupled, and (b) roof displacement is underestimated by the CQC modal combination rule (which would also limit accuracy of RSA for linearly elastic systems). Copyright © 2004 John Wiley & Sons, Ltd.