bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the dielectric properties of poly(o‐toluidine) and poly(o‐toluidine‐aniline) copolymer
Authors: John Honey , Thomas Rinku M. , Mathew K. T. , Joseph Rani 
Published: February 2004

AbstractPoly(o‐toluidine) (PoT) and poly(o‐toluidine co aniline) were prepared by using ammonium persulfate initiator, in the presence of 1M HCl. It was dried under different conditions: room temperature drying (48 h), oven drying (at 50°C for 12 h), or vacuum drying (under vacuum, at room temperature for 16 h). The dielectric properties, such as dielectric loss, conductivity, dielectric constant, dielectric heating coefficient, loss tangent, etc., were studied at microwave frequencies. A cavity perturbation technique was used for the study. The dielectric properties were found to be related to the frequency and drying conditions. Also, the copolymer showed better properties compared to PoT alone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 592–598, 2004
Synthesis and properties of acrylic‐based superabsorbent
Authors: Chen Xue‐Ping , Shan Guo‐Rong , Huang Jian , Huang Zhi‐Ming , Weng Zhi‐Xue 
Published: February 2004

AbstractAcrylic‐based superabsorbent polymers with partial‐neutralized acrylic acid were synthesized by inverse suspension polymerization. The effects of reaction parameters, including the concentration of crosslinking agent and initiator, the neutralization degree of monomer, the monomer concentration, and phase ratio of a system, on the water absorption have been investigated. Furthermore, to improve the properties of salt‐resistance and antielectrolyte for the polymer, acrylamide monomer containing nonionic and hydrophilic groups was introduced into the system, which can suppress the salt effect and homoion effect. The water absorption Q5/3 is proportional to the reciprocal of ionic strength, 1/S, which follows Flory's elasticity gel theory. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 619–624, 2004
Name that tune: A pilot study in finding a melody from a sung query
Authors: Pardo Bryan , Shifrin Jonah , Birmingham William 
Published: February 2004

AbstractWe have created a system for music search and retrieval. A user sings a theme from the desired piece of music. The sung theme (query) is converted into a sequence of pitch‐intervals and rhythms. This sequence is compared to musical themes (targets) stored in a database. The top pieces are returned to the user in order of similarity to the sung theme. We describe, in detail, two different approaches to measuring similarity between database themes and the sung query. In the first, queries are compared to database themes using standard string‐alignment algorithms. Here, similarity between target and query is determined by edit cost. In the second approach, pieces in the database are represented as hidden Markov models (HMMs). In this approach, the query is treated as an observation sequence and a target is judged similar to the query if its HMM has a high likelihood of generating the query. In this article we report our approach to the construction of a target database of themes, encoding, and transcription of user queries, and the results of preliminary experimentation with a set of sung queries. Our experiments show that while no approach is clearly superior to the other system, string matching has a slight advantage. Moreover, neither approach surpasses human performance.
Bioisosterism: Quantitation of Structure and Property Effects
Authors: Kier Lemont B. , Hall Lowell H. 
Published: February 2004

AbstractThe powerful concept of bioisosterism is presented as a method for selecting molecular groups for drug design and lead‐compound development. Three group‐structure characteristics are described for this purpose. The E‐State value for an attached atom is used as a measure of electrotopological group impact. The volume of the group is estimated from counts of σ, π, and lone‐pair n electrons, as embodied in the valence and simple connectivity δ values for atoms in the group. Polarity is described in terms of the polarity index Qv. Specific examples are given for commonly used groups. Parameter spaces encoding these three attributes are presented as examples that may be used to guide bioisostere selection in late‐stage drug‐design procedures. The method presented here is of practical value in the decision processes of molecular modification.
TMC‐95A Analogues with Endocyclic Biphenyl Ether Group as Proteasome Inhibitors
Authors: Kaiser Markus , Milbradt Alexander G. , Siciliano Carlo , Assfalg‐Machleidt Irmgard , Machleidt Werner , Groll Michael , Renner Christian , Moroder Luis 
Published: February 2004

AbstractTMC‐95A, a cyclic tripeptide metabolite of Apiospora montagnei, is a potent competitive inhibitor of proteasome. Based on the X‐ray structure of its complex with yeast proteasome, the synthetically challenging structure of this natural product was simplified in a first generation of analogues by replacing the highly oxidized side‐chain biaryl system with a phenyl‐oxindole group. In the present study, the TMC‐95 biaryl group was substituted with a biphenyl ether with retainment of significant proteasome inhibition. Because of the facile synthetic access of tripeptides containing in i, i+2 positions residues of the isodityrosine type, this new generation of TMC‐95 analogues may represent promising lead structures for further optimization of affinity and selectivity of proteasome inhibitors.
The Elusive Indigo Precursors in Woad (Isatis tinctoria L.) – Identification of the Major Indigo Precursor, Isatan A, and a Structure Revision of Isatan B
Authors: Oberthür Christine , Schneider Bernd , Graf Heidemarie , Hamburger Matthias 
Published: February 2004

AbstractA metabolite‐profiling study of shock‐frozen leaves of Isatis tinctoria L., an old indigo dye plant and medicinal herb, revealed a complex pattern of indigo‐forming compounds with higher polarities than the known indigo precursors isatan B and indican. These highly unstable compounds underwent rapid post‐harvest transformation and were not detected in air‐dried leaves. The major indigo precursor, named isatan A (4), was isolated by rapid normal‐phase and gel chromatography, along with isatan B (3). A full spectral data set of 3 showed that the previous structure assignment as ‘indoxyl‐5‐ketogluconate’ has to be revised to 1H‐indol‐3‐yl β‐D‐ribohex‐3‐ulopyranoside. Isatan A (4) was identified as 1H‐indol‐3‐yl 6′‐O‐(carboxyacetyl)‐β‐D‐ribohex‐3′‐ulopyranoside. In aqueous solution, glycosides 3 and 4 occur as hydrates and undergo rapid hydrolysis under very mild acidic or basic conditions.
Synthesis and Reactivity of Homogeneous and Heterogeneous Ruthenium‐Based Metathesis Catalysts Containing Electron‐Withdrawing Ligands
Authors: Krause Jens O. , Nuyken Oskar , Wurst Klaus , Buchmeiser Michael R. 
Published: February 2004

AbstractThe synthesis and heterogenization of new Grubbs–Hoveyda type metathesis catalysts by chlorine exchange is described. Substitution of one or two chlorine ligands with trifluoroacetate and trifluoromethanesulfonate was accomplished by reaction of [RuCl2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (IMesH2 = 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) with the silver salts CF3COOAg and CF3SO3Ag, respectively. The resulting compounds, [Ru(CF3SO3)2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (1), [RuCl(CF3SO3)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (2), and [Ru(CF3CO2)2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (3) were found to be highly active catalysts for ring‐closing metathesis (RCM) at elevated temperature (45 °C), exceeding known ruthenium‐based catalysts in catalytic activity. Turn‐over numbers (TONs) up to 1800 were achieved in RCM. Excellent yields were also achieved in enyne metathesis and ring‐opening cross metathesis using norborn‐5‐ene and 7‐oxanorborn‐5‐ene‐derivatives. Even more important, 3 was found to be highly active in RCM at room temperature (20 °C), allowing TONs up to 1400. Heterogeneous catalysts were synthesized by immobilizing [RuCl2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] on a perfluoroglutaric acid derivatized polystyrene‐divinylbenzene (PS‐DVB) support (silver form). The resulting supported catalyst [RuCl(polymer‐CH2‐O‐ CO‐CF2‐CF2‐CF2‐COO)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (5) showed significantly reduced activities in RCM (TONs = 380) compared with the heterogeneous analogue of 3. The immobilized catalyst, [Ru(polymer‐CH2‐O‐CO‐CF2‐CF2‐CF2‐COO)(CF3CO2)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (4) was obtained by substitution of both Cl ligands of the parent Grubbs–Hoveyda catalyst by addition of CF3COOAg to 5. Compound 4 can be prepared in high loadings (160 mg catalyst g−1 PS‐DVB) and possesses excellent activity in RCM with TONs up to 1100 in stirred‐batch RCM experiments. Leaching of ruthenium into the reaction mixture was unprecedentedly low, resulting in a ruthenium content <70 ppb (ng g−1) in the final RCM‐derived products.
Schallspektroskopische Charakterisierung konzentrierter Emulsionen
Authors: Babick F. , Ripperger S. 
Published: February 2004

AbstractDa die makroskopischen Eigenschaften einer Emulsion wesentlich von ihrem Dispersitätszustand bestimmt werden, liegt der Schlüssel zur Kontrolle, von Emulgierprozessen in der prozessnahen Charakterisierung desselben. Das erfordert Partikelmesstechniken, die keinerlei Probenvorbereitung verlangen und möglichst unmittelbar im Prozess eingesetzt werden können. Eine derartige Methode zur Ermittlung von Partikelgrößenverteilungen steht mit der Ultraschallspektroskopie prinzipiell zur Verfügung. In diesem Beitrag werden die Einsatzmöglichkeiten, aber auch die Applikationsgrenzen der Ultraschallspektroskopie systematisch herausgearbeitet, indem Erfahrungen zur Präzision der Messtechnik und zur Genauigkeit der Berechnungsmodelle vorgestellt, der Informationsgehalt von Schalldämpfungsspektren sowie auch die Sensitivität gegenüber den verschiedenen Stoffparametern aufgezeigt und der Einfluss von Emulgierhilfsstoffen auf das Schalldämpfungsverhalten von Emulsionen diskutiert.
Inhibition of intra‐ and extra‐cellular Tat function and HIV expression by pertussis toxin B‐oligomer
Authors: Rizzi Chiara , Alfano Massimo , Bugatti Antonella , Camozzi Maura , Poli Guido , Rusnati Marco 
Published: February 2004

AbstractHIV‐1‐transactivating factor Tat contributes to virus replication and to the onset of AIDS‐associated pathologies by targeting different infected and uninfected cell types. We previously demonstrated that the B‐oligomer of pertussis toxin (PTX‐B) inhibits HIV infection and replication in primary T cells and macrophages and Tat‐dependent HIV‐1 long terminal repeat (LTR) transactivation inT lymphoid Jurkat cells. Here we demonstrate that PTX‐B inhibits Tat‐dependent NF‐κB activation and HIV‐1 LTR‐transactivation in non‐permissive epithelial HL3T1 cells in a phosphatidylinositol 3′‐kinase‐dependent way. PTX‐B exerts its inhibition both when Tat is produced endogenously in transfected cells and in cells incubated with the extracellular Tat protein. In this latter case, PTX‐B does not interfere with extracellular Tat uptake by cells. PTX‐B inhibited also interleukin‐8 secretion and virus expression stimulated in chronically infected U1 promonocytic cells by intra‐ and/or extracellular Tat. The genetically modified holotoxin PT‐9 K/129G retains the capacity to inhibit Tat transactivating activity and HIV replication in both HIV‐permissive and non‐permissive cells. Inconclusion, PTX‐B acts as a "pleiotropic" inhibitor of Tat, and this may significantly contribute to the broad spectrum of anti‐HIV‐1 effects exerted by PTX‐B in different cell types, and suggests PTX‐B and its derivatives as prototypic for the development of anti‐Tat drugs.
Immunostimulating capacities of stabilized RNA molecules
Authors: Scheel Birgit , Braedel Sybilla , Probst Jochen , Carralot Jean‐Philippe , Wagner Hermann , Schild Hansjorg , Jung Günther , Rammensee Hans‐Georg , Pascolo Steve 
Published: February 2004

AbstractSince direct injection of naked mRNA induces an immune response, we tested the capacity of RNA to signal danger. We show here that mRNA molecules that are protected from immediate degradation either through interaction with cationic proteins (trans protection) or through chemical modification of the phosphodiester backbone (phosphorothioate RNA; cis protection) act as sequence‐independent danger signals on mouse DC. As opposed to CpG DNA, the cis‐stabilized RNA is degraded in a few minutes, does not activate B cells and, in contrast to double‐stranded RNA, requires MyD88 for activation of the DC. We postulate that phosphorothioate RNA, which mimics trans‐stabilized RNA, is a new PAMP.
Natural killer T cells contribute to airway eosinophilic inflammation induced by ragweed through enhanced IL‐4 and eotaxin production
Authors: Bilenki Laura , Yang Jie , Fan Yijun , Wang Shuhe , Yang Xi 
Published: February 2004

AbstractAlthough NKT cells have been found to be capable of modulating immune responses in several model systems, the role of NKT cells in allergy remains unclear. Using CD1 gene knockout (KO) mice, which lack NKT cells, we examined the function of NKT cells in the development of allergic inflammation induced by a common airborne human allergen, ragweed. The data showed that airway eosinophilia and mucus overproduction induced by ragweed were significantly reduced in CD1 KO mice, which was correlated with significantly lower allergen‐driven IL‐4 production and lower eotaxin responses in the airways of CD1 KO mice. Moreover, both ragweed‐specific and total serum IgE levels in CD1 KO mice were significantly lower than those in control BALB/c mice. The reduced allergic reaction in CD1 KO mice is not due to intrinsic deficiency because they showed normal levels of immune cells and function. In addition, in vivo stimulation of NKT cells using their natural ligand, α‐galactosylceramide, enhanced ragweed‐induced airway eosinophilia, IL‐4, and eotaxin production in control, but not CD1 KO mice. These data provide in vivo evidence for the involvementof NKT cells in the allergic mechanisms responsible for allergen‐driven cytokine and chemokine production and airway inflammation.
Expression profiling of IL‐10‐regulated genes in human monocytes and peripheral blood mononuclear cells from psoriatic patients during IL‐10 therapy
Authors: Jung Mechthild , Sabat Robert , Krätzschmar Jörn , Seidel Henrik , Wolk Kerstin , Schönbein Christiane , Schütt Sabine , Friedrich Markus , Döcke Wolf‐Dietrich , Asadullah Khusru , Volk Hans‐Dieter , Grütz Gerald 
Published: February 2004

AbstractInterleukin‐10 (IL‐10), originally identified as an inhibitor of pro‐inflammatory cytokine production, exerts multiple immunomodulatory functions. Its ability to inhibit a Th1 response has been used in clinical trials for the treatment of inflammatory diseases including psoriasis. However, little is known about the molecular mechanisms of IL‐10 functions. We aimed at identifying possiblemediators of in vitro IL‐10 treatment in monocytes by gene chip technology using Hu95a Affymetrix mRNA arrays with 12,000 genes. To prove relevance of the identified genes for the clinicalsituation we compared these in vitro results with genes being regulated by IL‐10 in peripheral blood mononuclear cells from psoriatic patients undergoing IL‐10 therapy. A high proportion of the 1,600 genes up‐regulated and 1,300 genes down‐regulated in vitro was found to be similarly regulated in vivo. Some genes, which were previously unknown to be regulated by IL‐10, can be assigned to known IL‐10 functions like e.g. the increase of pathogen clearance. Other new potentially immunomodulating genes have been identified to be regulated by IL‐10, but their impact needs to be experimentally evaluated. We could confirm a recently reported up‐regulation of heme oxygenase‐1 (HO‐1). However, we demonstrate that the anti‐inflammatory mechanisms of IL‐10 remain functional even when HO‐1 is irreversibly inhibited.
An MHC anchor‐substituted analog of myelin oligodendrocyte glycoprotein 35–55 induces IFN‐γ and autoantibodies in the absence of experimental autoimmune encephalomyelitis and optic neuritis
Authors: Ford Mandy L. , Evavold Brian D. 
Published: February 2004

AbstractPrevious strategies to ameliorate experimental autoimmune encephalitis (EAE) include the treatment of autoreactive T cells with altered peptide ligands, which contain amino acid substitutions at TCR contact residues. We recently showed that a variant of myelin oligodendrocyte glycoprotein (MOG) 35–55 possessing low affinity for MHC (45D) induced anergy in MOG 35–55‐specific T cells and reduced their encephalitogenicity upon adoptive transfer. Here we investigate the characteristics of the primary immune response to this MHC anchor‐substituted peptide. Overall, we observed that immunization with 45D resulted in the production of IFN‐γ and anti‐MOG 35–55 autoantibodies at levels similar to those of MOG 35–55‐immunized mice with active EAE. However, no symptoms of clinical or histological EAE or overt histological optic neuritis were observed in 45D‐immunized mice. Consistent with this finding, 45D‐immunized mice did not exhibit CD4+ infiltrates into the CNS. Therefore, MOG 35–55‐specific precursors stimulated with a weak ligand (45D) mediate some EAE‐associated effector functions but are unable to fully initiate the inflammatory process in the central nervous system that leads to clinical manifestation of EAE.
Control of cross‐presentation during dendritic cell maturation
Authors: Gil‐Torregrosa Beatriz C. , Lennon‐Duménil Ana Maria , Kessler Benedikt , Guermonprez Pierre , Ploegh Hidde L. , Fruci Doriana , Endert Peter Van , Amigorena Sebastian 
Published: February 2004

AbstractThe initiation of most cytotoxic immune responses requires MHC class I‐restricted presentation of internalized antigens to CD8+ T lymphocytes, a process called cross‐presentation. In dendritic cells (DC), the only antigen‐presenting cells that activate naive T cells, cross‐presentation is particularly efficient after internalization of opsonized antigens or immune complexes, which are cross‐presented through a proteasome‐ and transporter associated with antigen processing (TAP)‐dependent MHC class I antigen presentation pathway. We now show that FcγR‐mediated cross‐presentation is tightly regulated during DC maturation. Cross‐presentation increases soon after activation by lipopolysaccharides, and it is then inhibited in fully mature cells. The initial induction of cross‐presentation results from an increase of both antigen internalization and delivery to the cytosol, and from a slight rise in the activity of the proteasome and TAP. The subsequent block of cross‐presentation in mature DC is a consequence of the selective down‐modulation of antigen internalization and cytosolic delivery, while proteasome and TAP activities continue to rise. Therefore, FcγR‐mediated cross‐presentation is regulated during DC maturation by the selective control of antigen internalization and transport to the cytosol.
Subversion of effector CD8+ T cell differentiation in acute hepatitis C virus infection: the role of the virus
Authors: Accapezzato Daniele , Francavilla Vittorio , Rawson Pisana , Cerino Antonella , Cividini Agostino , Mondelli Mario U. , Barnaba Vincenzo 
Published: February 2004

AbstractIn a companion study, we showed a dichotomy between the expansion of central memory (CCR7+) hepatitis C virus (HCV)‐specific CTL and the incomplete memory effector differentiation in patients with acute HCV infection. Indeed, effector cells were unable to perform immediate functions, despite expressing the tissue‐homing phenotype of effector memory cells (CCR7–; semi‐effectors). However, since they promptly differentiated into full‐effectors upon IL‐2 contact, we suggested that the inhibitory effect by environmental (possibly viral) factors on IL‐2 production may have a pivotal role in generating the large population of semi‐effector CCR7–/IFN‐γ– CTL. In accord with this view, we report here strong evidence in support of circulating HCVcore protein (HCVcore) playing a central role in inhibiting effector CTL differentiation, but not memory CTL expansion. The regulatory HCVcore effect is related to inhibition of the signal transduction pathway instrumental for IL‐2 production, supporting the evidence that IL‐2 was capable both of pushing semi‐effector CTL to complete their effector cell program and of restoring the HCVcore‐dependent inhibitory effect. Therefore, the strength of CTL activation is dependent on the balance between the threshold of stimulatory signals and the viral interference capacities provided during priming.
Identification of a TLR4‐ and TRIF‐dependent activation program of dendritic cells
Authors: Weighardt Heike , Jusek Gabriela , Mages Jörg , Lang Roland , Hoebe Kasper , Beutler Bruce , Holzmann Bernhard 
Published: February 2004

AbstractDendritic cell activation by Toll‐like receptors (TLR) is crucial for the generation of protective immune responses. In addition to the common myeloid differentiation factor 88 (MyD88)‐dependent signaling pathway, TLR4 engages the adaptor protein Toll/IL‐1 receptor (TIR)‐domain‐containing adaptor inducing IFN‐β (TRIF), leading to interferon regulatory factor 3 (IRF‐3) activation and type I interferon production. Using microarray expression profiling we now identify TRIF as a major regulator of the TLR4‐triggered activation program of dendritic cells. We show that the expressionof 47% of the genes that are responsive to TLR4 stimulation in wild‐type dendritic cells is significantly altered in cells carrying a loss‐of‐function mutation of TRIF. Specifically, expression of IL‐12, IL‐18, and IL‐23 was impaired in the absence of functional TRIF, suggesting that TLR4‐promoted Th1 responses are TRIF‐dependent. Furthermore, we provide evidence that TRIF regulates TLR4‐mediated gene expression both by type I IFN‐dependent and ‐independent mechanisms. Whereas dendritic cell production of CXCL10 and CCL12 was dependent on both TRIF and the type I interferon receptor, expression of IL‐6 required TRIF but not type I interferon activity. Functional TRIF was also required for the normal induction of numerous genes considered important for host defense against diverse pathogens.Together, these data therefore identify TRIF as a crucial regulator of TLR4‐dependent dendritic cell responses.
Commentary: T cells get by with a little help from their friends
Authors: Klenerman Paul 
Published: February 2004

AbstractIn animal models, lymphocytic choriomeningitis virus (LCMV) may be controlled after acute infection or may establish various levels of persistence. Cytotoxic responses mediated by CD8+ T cells are responsible for both initial control of LCMV and for immunopathology. As discussed in this article, there is emerging evidence that the levels of antigen to which the immune system is exposed over time are important in controlling CD8+ T cell activation, memory responses and exhaustion, and that these levels are affected by the efficiency of T cell help and the presence of antibody. To enable lasting control of LCMV infection, CD8+ T cells, CD4+ T cell help and B cells are all required. These findings have important implications for the preventionand treatment of infection by viruses such as hepatitis B and C viruses, cytomegalovirus and HIV.See accompanying article http://dx.doi.org/10.1002/eji.200324717
N‐Acylhydrazines: Future Perspectives Offered by New Syntheses and Chemistry
Authors: Licandro Emanuela , Perdicchia Dario 
Published: February 2004

AbstractThis is a review of the most recent and useful synthetic methodologies for providing access to di‐ and trisubstituted hydrazides. New chemistry and new organometallic derivatives of the title compounds offer a new arsenal for the production of new functionalised derivatives, which are also useful as new biologically relevant molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)