bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass spectral studies of meso‐dialkyl, alkyl aryl and cycloalkyl calix(4)pyrroles under positive and negative ion electrospray ionization conditions
Authors: Bhaskar G. , Prabhakar S. , Ramanjaneyulu G. S. , Vairamani M. , Srinivasu V.N.V. , Srinivas K. 
Published: July 2007

AbstractA series of meso‐dialkyl, alkyl aryl and cycloalkyl calix(4)pyrroles (1–15) are studied under positive and negative ion electrospray ionization (ESI) conditions. The positive ion spectra show abundant [M + H]+ and [M + Na]+ ions and the negative ion spectra show the [M + Cl]− (the Cl− ions from the solvent) and [M − H]− ions. The collision induced dissociation (CID) spectra of [M + H]+, [M + Na]+, [M + Cl]− and [M − H]− ions are studied to understand their dissociation pathway and compared to that reported for M+ under electron ionization (EI) conditions. The β‐cleavage process that was diagnostic to M+ is absent in all the CID spectra of the ions studied under ESI. Dissociation of all the studied ions resulted in the fragment ions formed by sequential elimination of pyrrole (A) and/or dialkyl/alkyl aryl/cycloalkyl (B) groups involving hydrogen migration to pyrrole ring at each cleavage of AB bond, which clearly reveals the arrangement of A and B groups in the calix(4)pyrroles. The source of hydrogen that migrates to pyrrole ring during AB bond cleavage is investigated by the experiments on deuterated compounds and [M + D]+ ions; and confirmed that the hydrogen attached to pyrrole nitrogen, hydrogen on α‐carbon of alkyl group and the H+/Na+ ion that added during ESI process to generate [M + H]+/[M + Na]+ ions involve in the migration. The yields of [M + Na]+ ions are found to be different for the isomeric meso‐cycloalkyl compounds (cycloheptyl, and 2‐, 3‐ and 4‐methyl cyclohexyl) and for normal and N‐confused calix(4)pyrroles. The isomeric methyl and 3‐hydroxy/4‐hydroxy phenyl calix(4)pyrroles show specific fragmentation pattern during the dissociation of their [M − H]− ions. Copyright © 2007 John Wiley & Sons, Ltd.
The viral genetic background determines the outcome of coxsackievirus B3 infection in outbred NMRI mice
Authors: Schmidtke M. , Merkle I. , Klingel K. , Hammerschmidt E. , Zautner A.E. , Wutzler P. 
Published: July 2007

AbstractThe reasons for the different outcome of coxsackievirus B3 (CVB3)‐induced heart disease in humans are not well understood. Since there are no experimental data on the course of disease after infection with genetically different CVB3 in a natural variable population until now, we studied the outcome of virus infection in outbred NMRI mice after inoculation of genetically different CVB3 variants. Adult male mice were inoculated with seven closely related CVB3 variants. The histopathological changes of heart and pancreas tissue, antibody induction, virus titers, and persistence of viral positive‐ as well as negative‐strand RNA in spleen and heart tissue were compared at day 7 or day 28 after infection to detect prerequisites and predictive factors for chronic myocarditis. Six CVB3 variants infected NMRI mice. CVB3 infection (i) did not induce detectable myocardial injury, (ii) caused signs of healing up acute myocarditis or (iii) ongoing chronic myocarditis. Neither IgG antibody responses nor the extent of destruction of exocrine pancreatic tissue or viral RNA load in spleen did correlate with myocardial histopathology. In contrast, a high persistent viral RNA load in heart tissue specimens was characteristic for mice developing chronic myocarditis. The results of the present study corroborate high viral load in the acute stage of myocarditis and high amounts of persisting CVB3 RNA in heart tissue as predictive marker of chronic myocarditis. The outcome of CVB3‐induced heart disease in outbred NMRI mice depends strongly on the viral genetic background. In particular an important role of viral capsid proteins is suggested. J. Med. Virol. 79:1334–1342, 2007. © Wiley‐Liss, Inc.
Proteasomal degradation of core protein variants from chronic hepatitis B patients
Authors: Braun Sabine , Zajakina Anna , Aleksejeva Jekaterina , Sharipo Anatoly , Bruvere Ruta , Ose Velta , Pumpens Paul , Garoff Henrik , Meisel Helga , Kozlovska Tatyana 
Published: July 2007

AbstractThe accumulation of complex hepatitis B virus (HBV) variants with internal in‐frame deletions in the C gene in immunosuppressed renal transplant recipients is associated with a severe course of the infection leading to end‐stage liver disease (ESLD). A set of six HBV C genes with internal in‐frame deletions corresponding to the pattern of HBV population in immunosuppressed patients has been expressed in two different eukaryotic cell lines. Synthesis and proteasomal degradation of HBV core (HBc) protein variants were compared with those of the wild‐type HBc. In all cases, the steady‐state level of internally deleted HBc proteins, predominantly with longer deletions, were considerably lower and turnover was significantly higher in comparison with those of the wild‐type HBc, since all deletion variants were degraded rapidly via the proteasome pathway. Involvement and consequences of the proteasomal degradation machinery in the HBc protein turnover during HBV infection with complex HBV variants in the immunosuppressed patients are discussed. J. Med. Virol. 79:1312–1321, 2007. © Wiley‐Liss, Inc.
Detection of drug resistance mutations as a predictor of subsequent virological failure in patients with HIV‐1 viral rebounds of less than 1,000 RNA copies/ml
Authors: Verhofstede Chris , Van Wanzeele Filip , Van Der Gucht Bea , Pelgrom Jolanda , Vandekerckhove Linos , Plum Jean , Vogelaers Dirk 
Published: July 2007

AbstractIn order to evaluate the usefulness of resistance testing after a viral rebound with plasma HIV RNA levels of less than 1,000 copies (c)/ml, genotyping was performed on 39 samples from patients on highly active antiretroviral therapy (HAART) showing a viremia of over 50 c/ml up to a maximum of 1,000 c/ml after at least one undetectable viral load result. Protease and reverse transcriptase (RT) sequences were obtained for all 39 samples. In 10 (25.6%) of the samples, mutations not seen before the initiation of the regimen were observed. The M184V/I mutation was the most prevalent but in several patients a combination of multiple mutations was detected. Follow‐up samples were available for 34 patients. In six (85.71%) out of seven patients with new mutations, the viral load on the follow‐up visit remained detectable, indicating true failure, compared to 6 (31.6%) true failures out of 19 patients in whom only wild type virus was detected (P = 0.02) and three (37.5%) out of eight patients in whom only the mutations already present at the initiation of HAART were seen (P = 0.08). The results indicate that reliable resistance testing can be performed on samples with a viral burden of less than 1,000 c/ml and demonstrate that multiple drug resistance mutations can be selected at low viral load rebounds. Most importantly, detection of resistance mutations in viral rebound samples was predictive of subsequent virological failure. J. Med. Virol. 79:1254–1260, 2007. © Wiley‐Liss, Inc.
Metallocenic Isotactic Poly(propylene) and its Copolymers with 1‐Hexene and Ethylene
Authors: Arranz‐Andrés Javier , Suárez Inmaculada , Peña Begoña , Benavente Rosario , Pérez Ernesto , Cerrada María L. 
Published: July 2007

AbstractA comprehensive study of the structure and properties has been performed for copolymers of propylene‐1‐hexene, CiPH, and propylene‐ethylene, CiPE, synthesized by an isotactic metallocene catalyst system. The comonomer content constitutes the most important factor affecting the structure and properties of these CiPH and CiPE copolymers, although the length of the comonomer is also very important. Thus, a considerable decrease in crystallinity is observed in the two kinds of copolymers as the comonomer content increases. The structure in the CiPH copolymers evolves, however, from the typical, monoclinic crystal lattice to mesomorphic‐like, ordered entities for the highest 1‐hexene molar fraction, whereas in the CiPE copolymers the structural evolution with molar fraction goes from a monoclinic lattice to an almost amorphous material. All of these variations in crystal structure significantly influence the viscoelastic and mechanical behavior of these CiPH and CiPE copolymers. Consequently, the location and intensity of the different relaxation mechanisms, as well as the rigidity parameters (storage and Young's moduli and microhardness) and deformation mechanism are strongly dependent upon composition.magnified image
Characterisation of Surface Activity of Carbon Black and its Relation to Polymer‐Filler Interaction
Authors: Schröder Andreas , Klüppel Manfred , Schuster Robert H. 
Published: July 2007

AbstractThe surface activity of commercial and experimental carbon blacks varying in particle size and primary aggregate structure was investigated with regard to surface roughness and energetic surface structure of primary particles. The energetic surface structure was described by the site energy distribution function f(Q), which was determined mainly from the gas adsorption isotherms of ethene. It was found that the surface of carbon black was energetically very heterogeneous. It consisted of at least four different adsorption sites (I: Q ≈ 16 kJ · mol−1; II: Q ≈ 20 kJ · mol−1; III: Q ≈ 25 kJ · mol−1; IV: Q ≈ 30 kJ · mol−1). The fraction of the sites I–IV depended on the production process of the carbon black grades and the particle size. For the furnace blacks, the fraction of high‐energy sites decreased significantly with particle size and disappeared almost completely during graphitisation. This indicates that the reinforcing potential of carbon black is closely related to the amount of highly energetic sites that can be well quantified by the applied gas adsorption technique. The surface roughness was characterised by the surface fractal dimension, Ds, which was determined by two different techniques: the yardstick‐method and the extended Frenkel‐Halsey‐Hill‐theory (fractal FHH‐theory). It is found that the furnace blacks have an almost equal roughness with a surface fractal dimension of Ds ≈ 2.6 beyond a length scale z ≈ 6 nm. This result is shown to be in fair agreement with analytical models and computer simulations of surface growth of carbon black in a furnace reactor.magnified image
Molecular Dynamics Simulation of the Formation of Polymer Networks
Authors: Yang Wen , Wei Dongshan , Jin Xigao , Liao Qi 
Published: July 2007

AbstractThe random end linking of different amounts of trifunctional crosslinkers with 3 000 prepolymer linear chains, with length varying from 10 to 30 monomers, to form networks at different system number densities was dynamically simulated by the molecular dynamics method. Investigation of the crosslinking kinetics shows that, with a stoichiometric number of crosslinkers present, the time evolution of free ends fraction decays as a power law in timet−3/4. This scaling behavior is different from the one in a dense polymer melt. Structural analyses of the resulting networks indicate that the imperfections of the network structure strongly depend on the initial synthesis conditions including the initial system number density and the ratio of crosslinkers to precursor polymer chain ends.magnified image
Signal transducer and activator of transcription 3 (Stat3) in epithelial carcinogenesis
Authors: Kim Dae Joon , Chan Keith S. , Sano Shigetoshi , DiGiovanni John 
Published: July 2007

AbstractSignal transducer and activator of transcription 3 (Stat3) is one of a family of cytoplasmic proteins that participate in normal cellular responses to cytokines and growth factors as transcription factors. Stat3 modulates various physiological functions including cell survival, cell‐cycle regulation, and angiogenesis through regulation of gene expression, and its constitutive activation is associated with a number of human epithelial cancers. Recent studies with skin‐specific gain and loss of Stat3 function transgenic mice have shown that Stat3 plays critical roles in skin carcinogenesis. Multistage skin carcinogenesis bioassays performed with these transgenic mice clearly demonstrate that Stat3 is required for both tumor initiation and promotion through regulation of genes involved in survival and proliferation, respectively. Stat3 also plays a role in malignant progression of skin tumors by regulating genes that are involved in angiogenesis and invasion. Further studies have revealed that Stat3 plays a critical role in epidermal cell proliferation and survival following exposure to ultraviolet B (UVB) irradiation. In addition, Stat3 is constitutively active in UVB‐induced skin tumors from both mice and humans. Collectively, these studies suggest that Stat3 may be a potential target for both the prevention and treatment of human epithelial cancers including skin cancer. © 2007 Wiley‐Liss, Inc.
Translational experimental therapeutics: The translation of laboratory‐based discovery into disease‐related therapy
Authors: Kieburtz Karl , Olanow C. Warren 
Published: July 2007

AbstractIn the past decade, there has been an increasing emphasis on laboratory‐based translational research. This has led to significant scientific advances in our understanding of disease mechanisms and in the development of novel approaches to therapy such as gene therapy, RNA interference, and stem cells. However, the translation of these remarkable scientific achievements into new and effective disease‐modifying therapies has lagged behind these scientific accomplishments. We use the term “translational experimental therapeutics” to describe the pathway between the discovery of a basic disease mechanism or novel therapeutic approach and its translation into an effective treatment for patients with a specific disease. In this article, we review the components of this pathway, and discuss issues that might impede this process. Only by optimizing this pathway can we realize the full therapeutic potential of current scientific discoveries and translate the astounding advances that have been accomplished in the laboratory into effective treatments for our patients. Mt Sinai J Med 74: 7‐14, 2007. Copyright © 2007 Mount Sinai School of Medicine
The role of the pathologist in translational and personalized medicine
Authors: Perl Daniel P. 
Published: July 2007

AbstractOver the years, pathologists have served to make morphologic diagnoses for clinicians when provided with a biopsy or surgically resected tissue specimen. Traditionally, pathologists have used a series of morphologic techniques and relied on the microscopic appearance of resected tissues to determine a pathologic diagnosis and, with respect to neoplastic lesions, provide predictions of the potential growth pattern that might be anticipated. With the introduction of the techniques of molecular biology in medicine, the role of the pathologist has changed as have the tools available for characterizing pathologic specimens. With the pathologist's unique perspective on disease processes and access to tissue specimens from the operating room, he has become a key player in the area of translational and personalized medicine and the development of new approaches to diagnosis and translational research. Mt Sinai J Med 74:22–26, 2007. © 2007 Mount Sinai School of Medicine
A likely case of scurvy from early Bronze Age Britain
Authors: Mays S. 
Published: July 2007

AbstractA probable case of scurvy is identified in a child skeleton from England, dating to 2200–1970 BC. Lesions were mainly restricted to the ectocranium, but some endocranial lesions were also seen. This appears to be the earliest reported example of scurvy from Britain, and adds to the very few palaeopathological case descriptions available for the disease in infants and young children from Europe. Copyright © 2007 John Wiley & Sons, Ltd.
Structure and performance of discrete H∞ optimal control
Authors: Foley M. W. , Harris T. J. 
Published: July 2007

AbstractIn recent years a good deal of attention has been focused on the development of model‐based controllers optimizing infinity‐norm performance objectives. The motivation behind this is a perceived need for controllers which are more robust to modelling errors than those which result from conventional LQ designs. At the present time, however, numerical solution of the H∞ problems remains very much an open issue. This paper examines Grimble's approach to the design of discrete‐time H∞ control laws for univariate plants subject to stationary stochastic disturbances. The structure of the controller is analysed using the internal model control concept of Garcia and Morari and is compared with that obtained for a polynomial LQ scheme. Simulation results are presented for both minimum phase and non‐minimum phase systems in which the H∞ technique is seen to be inferior to LQ in terms of performance, robustness to parametric mismatch and computational complexity.
A method for assessing the choice of polymeric materials for specific applications
Authors: Pitol‐Filho Luizildo , Garcia‐Valls Ricard 
Published: July 2007

AbstractPolymeric membranes have several applications of high technological impact: reverse osmosis, controlled drug delivery and fuel cell stacks, among many others. However, the choice of the most appropriate polymer for a specific application entails exhaustive experimental work, which may be reduced significantly if the chemical structures of polymer and transported molecules are taken into account. From physico‐chemical data such as viscosity (for penetrants) and relaxation times (for polymers), free‐volume parameters might be estimated, as well as Flory‐Huggins interaction coefficients. By combining both theories, diffusivity of molecules through dense polymers may be evaluated, what allows us to predict membrane properties as water uptake, or operation data as equilibrium concentrations for pervaporation and methanol crossover in the case of fuel cell applications. Simulation results are compared with those in the literature and agreement between the sets of data recommends the proposed method as a helpful tool to decide which polymer is more adequate for a specific purpose. POLYM. ENG. SCI., 47:1220–1227, 2007. © 2007 Society of Plastics Engineers
A combination of neutral loss and targeted product ion scanning with two enzymatic digestions facilitates the comprehensive mapping of phosphorylation sites
Authors: Casado‐Vela Juan , Ruiz Edgar J. , Nebreda Angel R. , Casal J. Ignacio 
Published: July 2007

AbstractWe propose here a new strategy for the exhaustive mapping of phosphorylation sites in the Xenopus laevis Cdc25 phosphatase, which regulates cell cycle progression in eukaryotic cells. Two different MS analyses in a linear IT were used to identify the phosphorylated residues. First, a data‐dependent neutral loss (DDNL) analysis triggered the fragmentation of peptides that show enhanced neutral loss of phosphoric acid. Second, a targeted product ion scanning (TPIS) mass analysis was carried out in which MS2 events are triggered for specific m/z values. Full coverage of the protein sequence was obtained by combining the two analyses with two enzymatic digestions, trypsin and chymotrypsin, yielding a comprehensive map of the phosphorylation sites. Previous reports have shown Cdc25C to be phosphorylated by Cdc2–cyclin B at four residues (Thr48, Thr67, Thr138 and Ser205). By using this combination of scan modes, we have identified four additional phosphorylation sites (Thr86, Ser99, Thr112 and Ser163) in a recombinant Cdc25C protein containing 198 residues of the NH2‐terminal noncatalytic domain. The sensitivity of this combined approach makes it extremely useful for the comprehensive characterization of phosphorylation sites, virtually permitting complete coverage of the protein sequence with peptides within the mass detection range of the linear IT.
Proteome‐wide changes induced by the Hsp90 inhibitor, geldanamycin in anaplastic large cell lymphoma cells
Authors: Schumacher Jonathan A. , Crockett David K. , Elenitoba‐Johnson Kojo S. J. , Lim Megan S. 
Published: July 2007

AbstractThe molecular chaperone heat shock protein 90 (Hsp90) affects the function of many oncogenic signaling proteins including nucleophosmin‐anaplastic lymphoma kinase (NPM‐ALK) expressed in anaplastic large cell lymphoma (ALCL). While ALK‐positive ALCL cells are sensitive to the Hsp90 inhibitor and the geldanamycin (GA) analog, 17‐allylamino‐17‐demethoxygeldanamycin (17‐AAG), the proteomic effects of these drugs on ALK‐positive ALCL cells are unpublished. In this study, we investigated the cellular, biologic, and proteomic changes occurring in ALK‐positive ALCL cells in response to GA treatment. GA induced G2/M cell cycle arrest and caspase‐3‐mediated apoptosis. Furthermore, quantitative proteomic changes analyzed by cleavable isotope‐coded affinity tag™‐LC‐MS/MS (cICAT™‐LC‐MS/MS) identified 176 differentially expressed proteins. Out of these, 49 were upregulated 1.5‐fold or greater and 70 were downregulated 1.5‐fold or greater in GA‐treated cells. Analysis of biological functions of differentially expressed proteins revealed diverse changes, including induction of proteins involved in the 26S proteasome as well as downregulation of proteins involved in signal transduction and protein and nucleic acid metabolism. Pathway analysis revealed changes in MAPK, WNT, NF‐κB, TGFβ, PPAR, and integrin signaling components. Our studies reveal some of the molecular and proteomic consequences of Hsp90 inhibition in ALK‐positive ALCL cells and provide novel insights into the mechanisms of its diverse cellular effects.
Attapulgite and ultrasonic oscillation induced crystallization behavior of polypropylene
Authors: Zhao Lijuan , Du Qin , Jiang Genjie , Guo Shaoyun 
Published: July 2007

AbstractIn this article, the effect of ultrasonic oscillation on the dispersed morphology of attapulgite in polypropylene (PP) and crystallizing kinetics of PP/attapulgite composites prepared through extrusion in the presence and the absence of ultrasonic oscillation were studied. X‐ray diffraction analysis results showed that ultrasonic oscillation did not change attapulgite crystal structure during extrusion in PP/attapulgite composites. On the other hand, scanning electron microscopy and transmission electron microscope photographs indicated that ultrasonic oscillation promoted the dispersion of attapulgite particles in PP matrix. The dispersed morphology of attapulgite and ultrasound oscillation affected the crystalline form, nucleation rate, crystallization temperature, crystallinity, and spherulite size of PP crystals. PP transcrystals were formed on the attapulgite particle surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2300–2308, 2007