bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tamoxifen‐Loaded Polymeric Micelles: Preparation, Physico‐Chemical Characterization and In Vitro Evaluation Studies
Authors: Cavallaro Gennara , Maniscalco Laura , Licciardi Mariano , Giammona Gaetano 
Published: November 2004

AbstractSummary: Several samples of polymeric micelles, formed by amphiphilic derivatives of PHEA, obtained by grafting into polymeric backbone of PEGs and/or hexadecylamine groups (PHEA‐PEG‐C16 and PHEA‐C16) and containing different amount of Tamoxifen, were prepared. All Tamoxifen‐loaded polymeric micelles showed to increase drug water solubility. TEM studies provided evidence of the formation of supramolecular core/shell architectures containing drug, in the nanoscopic range and with spherical shape. Samples with different amount of encapsulated Tamoxifen were subjected to in vitro cytotoxic studies in order to evaluate the effect of Tamoxifen micellization on cell growth inhibition. All samples of Tamoxifen‐loaded polymeric micelles showed a significantly higher antiproliferative activity in comparison with free drug, probably attributable to fluidification of cellular membranes, caused by amphiphilic copolymers, that allows a higher penetration of the drug into tumoral cells. To gain preliminary information about the potential use of prepared micelles as Tamoxifen drug delivery systems, studies evaluating drug release ability of micelle systems in media mimicking biological fluids (buffer solutions at pH 7.4 and 5.5) and in human plasma were carried out. These studies, performed evaluating the amount of Tamoxifen that remains in solution as a function of time, showed that at pH 7.4, as well as in plasma, PHEA‐C16 polymeric micelles were able to release lower drug amounts than PHEA‐PEG5000‐C16 ones, while at pH 5.5, the behavior difference between two kind of micelles was less pronounced.
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Atom‐Transfer Radical Polymerization: A Strategy for the Synthesis of Halogen‐Free Amino‐Functionalized Poly(methyl methacrylate) in a One‐Pot Reaction
Authors: Sadhu Veera Bhadraiah , Pionteck Jürgen , Voigt Dieter , Komber Hartmut , Fischer Dieter , Voit Brigitte 
Published: November 2004

AbstractSummary: An initiator containing an alkyl bromide unit and a protected amine functional group is used with CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA), in a 1:2 molar ratio with respect to initiator concentration, in order to obtain amino‐group terminated as well as halogen‐free poly(methyl methacrylate) (PMMA) in a one‐pot atom‐transfer radical polymerization (ATRP). The terminal bromines are replaced by hydrogen atoms of the PMDETA ligand, which acts as a transfer agent. However, terminating side reactions like disproportionation or dehydrobromination occur from the beginning of the polymerization. Kinetic studies by in‐line Raman spectroscopy and off‐line 1H NMR spectroscopy revealed that the controlled character of the ATRP is lost under these conditions. The measured molecular weights were consistently higher than the theoretical ones and the molecular weight distributions are relatively broad. Thermal analysis of the obtained poly(methyl methacrylate) shows two main degradation steps, one starting from unsaturated end groups (depolymerization), and one caused by main‐chain scission, a further proof for the occurrence of terminating side reactions.Structural analysis of PMMA by matrix‐assisted laser desorption‐ionization mass spectrometry.magnified imageStructural analysis of PMMA by matrix‐assisted laser desorption‐ionization mass spectrometry.
Behavior of Active Sites in a Changing, Supported Metallocene Catalyst Particle: Modeling Monomer Transport and Kinetics
Authors: Chiovetta Mario G. , Estenoz Diana A. 
Published: November 2004

AbstractSummary: Support‐catalyst‐polymer particles composed of millions of microparticles arranged in cells and having silica nuclei covered with metallocene‐methyl alumoxane (MAO) active sites are studied to analyze cell participation during polymerization. Main variables are the changing particle morphology and the kinetic‐diffusion effects determining local monomer availability during residence time. The phenomena were studied by means of a mathematical model used to produce a set of predictions for particles polymerizing ethylene in a toluene slurry continuous stirred tank reactor (CSTR) under various operating conditions. This information is employed to predict the micro‐ and macroparticle behavior in situations designed to explore catalyst activities, monomer availabilities and reactor conditions. Kinetic constants and concentrations range from reference values up to 6 times these figures, with reactor temperatures between 323 and 353 K and particle Reynolds numbers on a 1 to 10 relative scale. Heat transfer and temperature elevation during polymerization are predicted, with no relevant overheating observed. Morphology changes, in the form of density profiles inside the support‐catalyst‐polymer particle, are monitored with time, and their interaction with transport and reaction phenomena analyzed. Increasing catalyst activity alone may not produce proportional raises in yield; it appears more efficient to improve the monomer availability instead. High catalyst activity may produce monomer depletion at inner cells delaying their fragmentation and decreasing local polymer‐production.Cell density vs. time for cells located at the exterior, at the center and at half the radius of the macroparticle.magnified imageCell density vs. time for cells located at the exterior, at the center and at half the radius of the macroparticle.
Preparation and Characterization of Organic/Inorganic Polymer Composites Based on Mg‐Silicates
Authors: Pankow Oliver , Schmidt‐Naake Gudrun 
Published: November 2004

AbstractSummary: An organic‐inorganic hybrid material consisting of a 3‐(methacryloxy)propyl functionalized SiO2/MgO framework was synthesized. This hybrid was successfully reacted with styrene, butyl acrylate and butyl methacrylate via a free radical emulsion polymerization to form polymer composites. The polymer composites were investigated by means of FT‐IR spectroscopy, TGA, DSC and rheometry. It is shown that the polymer is linked covalently to the organic/inorganic hybrid. Although the polymer content is rather low, the composites exhibit a polymer‐like character and enhanced mechanical properties compared to the corresponding homopolymers.
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Morphology Dependent Double Yielding in Injection Molded Polycarbonate/Polyethylene Blend
Authors: Li Zhong‐Ming , Huang Chen‐Guang , Yang Wei , Yang Ming‐Bo , Huang Rui 
Published: November 2004

AbstractSummary: Polycarbonate (PC)/polyethylene (PE) blend was injection molded at different molding temperatures. The morphological observation by scanning electronic microscope (SEM) indicated that the sample molded at 190 °C contained only uniformly dispersed spherical PC particles. The samples molded at 230 and 275 °C had a typical skin‐core structure, and there were many injection‐induced PC fibers in the subskin. While the sample molded at 190 °C had the usual stress‐strain behavior, the samples obtained at 230 and 275 °C showed apparently double yielding behavior. It was suggested that the double yielding points were morphology‐dependent. The first one was the result of the yielding of PE at low strain, and the second one was caused by the yielding of the PC fibers. Moreover, it is the frictional force in the interfaces between PC and PE that transferred the stress to the PC fibers, hence giving rise to the reinforcement of PE by PC.Stress‐strain curves of PC/PE blends injection molded at various temperatures showing first (I) and second (II) yielding points.magnified imageStress‐strain curves of PC/PE blends injection molded at various temperatures showing first (I) and second (II) yielding points.
Bacillus cereus, the causative agent of an emetic type of food‐borne illness
Authors: Ehling‐Schulz Monika , Fricker Martina , Scherer Siegfried 
Published: November 2004

AbstractBacillus cereus is the causative agent of two distinct forms of gastroenteritic disease connected to food‐poisoning. It produces one emesis‐causing toxin and three enterotoxins that elicit diarrhea. Due to changing lifestyles and eating habits, B. cereus is responsible for an increasing number of food‐borne diseases in the industrial world. In the past, most studies concentrated on the diarrhoeal type of food‐borne disease, while less attention has been given to the emetic type of the disease. The toxins involved in the diarrhoeal syndrome are well‐known and detection methods are commercially available, whereas diagnostic methods for the emetic type of disease have been limited. Only recently, progress has been made in developing identification methods for emetic B. cereus and its corresponding toxin. We will summarize the data available for the emetic type of the disease and discuss some new insights in emetic strain characteristics, diagnosis, and toxin synthesis.
Molecular characteristics of Escherichia coli serogroup O78 strains isolated from diarrheal cases in bovines urge further investigations on their zoonotic potential
Authors: Ewers Christa , Schüffner Claudia , Weiß Reinhard , Baljer Georg , Wieler Lothar H. 
Published: November 2004

AbstractWe investigated the virulence properties and clonal relationship of 21 Escherichia coli strains of serogroup O78 isolated from diarrhoeic cattle and calves. Isolates were screened for 18 genes representing virulence features of different Escherichia coli pathotypes. None of the strains harboured enterotoxin‐genes estIa/Ib, eltIa/Ib, or Shiga toxin (stx) genes, genes involved in adhesion (eae, f5, f41) hemolysin gene hlyA or invasion gene ipaC. With a high prevalence we detected enterotoxin astA (61.9%), genes involved in iron acquisition, like fyuA, irp (each 57.1%) and iucD (81.0%), and the operon sequence of Colicin V plasmids (38.1%). Some strains possessed toxin genes cdt‐IIIB and cnf1/2 (both 14.3%), the invasion gene tia (23.8%), and the serine protease encoding gene espP (23.8%). Moreover, we could show that E. coli O78 strains under investigation were able to adhere to and invade MDBK‐cells with varying efficiencies. The results indicate that the closely related O78 strains, constituting two major PFGE‐clusters, harbor various virulence features for bovine intestinal disease but cannot be grouped into one of the common E. coli intestinal pathogenic or other pathotypes according to their virulence gene pattern. Nevertheless, the ability to adhere, invade or harbor toxin genes lets us suggest that O78 strains isolated from diarrheal cases in bovines urges further investigations on the zoonotic potential of these strains.
A 2‐path approach for odd‐diameter‐constrained minimum spanning and Steiner trees
Authors: Gouveia Luis , Magnanti Thomas L. , Requejo Cristina 
Published: November 2004

AbstractIn a previous article, using underlying graph theoretical properties, Gouveia and Magnanti (2003) described several network flow‐based formulations for diameter‐constrained tree problems. Their computational results showed that, even with several enhancements, models for situations when the tree diameter D is odd proved to be more difficult to solve than those when D is even. In this article we provide an alternative modeling approach for the situation when D is odd. The approach views the diameter‐constrained minimum spanning tree as being composed of a variant of a directed spanning tree (from an artificial root node) together with two constrained paths, a shortest and a longest path, from the root node to any node in the tree. We also show how to view the feasible set of the linear programming relaxation of the new formulation as the intersection of two integer polyhedra, a so‐called triangle‐tree polyhedron and a constrained path polyhedron. This characterization improves upon a model of Gouveia and Magnanti (2003) whose linear programming relaxation feasible set is the intersection of three rather than two integer polyhedra. The linear programming gaps for the tightened model are very small, typically less than 0.5%, and are usually one third to one tenth of the gaps of the best previous model described in Gouveia and Magnanti (2003). Moreover, using the new model, we have been able to solve large Euclidean problem instances that are not solvable by the previous approaches. © 2004 Wiley Periodicals, Inc.
Finite‐difference schemes for transport‐dominated equations using special collocation nodes
Authors: Fatone Lorella , Funaro Daniele , Giova Rafaella 
Published: November 2004

AbstractWe introduce finite‐difference schemes based on a special upwind‐type collocation grid, in order to obtain approximations of the solution of linear transport‐dominated advection‐diffusion problems. The method is well suited when the diffusion parameter is very small compared to the discretization parameter. A theory is developed and many numerical experiments are shown. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
C‐C chemokine receptor 2 (CCR2) deficiency improves bleomycin‐induced pulmonary fibrosis by attenuation of both macrophage infiltration and production of macrophage‐derived matrix metalloproteinases
Authors: Okuma Toshiyuki , Terasaki Yasuhiro , Kaikita Koichi , Kobayashi Hironori , Kuziel William A , Kawasuji Michio , Takeya Motohiro 
Published: November 2004

AbstractMacrophage infiltration is implicated in various types of pulmonary fibrosis. One important pathogenetic process associated with pulmonary fibrosis is injury to basement membranes by matrix metalloproteinases (MMPs) that are produced mainly by macrophages. In this study, C‐C chemokine receptor 2‐deficient (CCR2−/−) mice were used to explore the relationship between macrophage infiltration and MMP activity in the pathogenesis of pulmonary fibrosis, using the bleomycin‐induced model of this disease process. CCR2 is the main (if not only) receptor for monocyte chemoattractant protein‐1/C‐C chemokine ligand 2 (MCP‐1/CCL2), which is a critical mediator of macrophage trafficking, and CCR2 −/− mice demonstrate defective macrophage migration. Pulmonary fibrosis was induced in CCR2−/− and wild‐type (CCR2+/+) mice by intratracheal instillation of bleomycin. No significant differences in the total protein concentration in bronchoalveolar lavage (BAL) fluid, or in the degree of histological lung inflammation, were observed in the two groups until day 7. Between days 3 and 21, however, BAL fluid from CCR2−/− mice contained fewer macrophages than BAL fluid from CCR2+/+ mice. Gelatin zymography of BAL fluid and in situ zymography revealed reduced gelatinolytic activity in CCR2−/− mice. Immunocytochemical staining showed weaker expression of MMP‐2 and MMP‐9 in macrophages in BAL fluid from CCR2−/− mice at day 3. Gelatin zymography of protein extracted from alveolar macrophages showed reduced gelatinolytic activity of MMP‐2 and MMP‐9 in CCR2−/− mice. At days 14 and 21, lung remodelling and the hydroxyproline content of lung tissues were significantly reduced in CCR2−/− mice. These results suggest that the CCL2/CCR2 functional pathway is involved in the pathogenesis of bleomycin‐induced pulmonary fibrosis and that CCR2 deficiency may improve the outcome of this disease by regulating macrophage infiltration and macrophage‐derived MMP‐2 and MMP‐9 production. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Renal ACE2 expression in human kidney disease
Authors: Lely AT , Hamming I , van Goor H , Navis GJ 
Published: November 2004

AbstractAngiotensin‐converting enzyme 2 (ACE2) is a recently discovered homologue of angiotensin‐converting enzyme (ACE) that is thought to counterbalance ACE. ACE2 cleaves angiotensin I and angiotensin II into the inactive angiotensin 1–9, and the vasodilator and anti‐proliferative angiotensin 1–7, respectively. ACE2 is known to be present in human kidney, but no data on renal disease are available to date. Renal biopsies from 58 patients with diverse primary and secondary renal diseases were studied (hypertensive nephropathy n = 5, IgA glomerulopathy n = 8, minimal change nephropathy n = 7, diabetic nephropathy n = 8, focal glomerulosclerosis n = 5, vasculitis n = 7, and membranous glomerulopathy n = 18) in addition to 17 renal transplants and 18 samples from normal renal tissue. Immunohistochemical staining for ACE2 was scored semi‐quantitatively. In control kidneys, ACE2 was present in tubular and glomerular epithelium and in vascular smooth muscle cells and the endothelium of interlobular arteries. In all primary and secondary renal diseases, and renal transplants, neo‐expression of ACE2 was found in glomerular and peritubular capillary endothelium. There were no differences between the various renal disorders, or between acute and chronic rejection and control transplants. ACE inhibitor treatment did not alter ACE2 expression. In primary and secondary renal disease, and in transplanted kidneys, neo‐expression of ACE2 occurs in glomerular and peritubular capillary endothelium. Further studies should elucidate the possible protective mechanisms involved in the de novo expression of ACE2 in renal disease. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Rate enhancement for nitroxide stable free radical polymerization of n‐butyl acrylate by dodecylbenzenesulfonic acid
Authors: Cheng Kuo‐Chung , Chen Jiun‐Jeng , Chiu Wen‐Yen , Wang Lee Yih , Wang Ping‐Chieh 
Published: November 2004

AbstractDodecylbenzenesulfonic acid, DDBSA, was chosen as a new rate‐accelerating additive for 2,2,6,6,‐teramethyl‐1‐piperidinyloxy (TEMPO)‐mediated stable free radical polymerization of n‐butyl acrylate (n‐BA) monomers with 2,2′‐azobisisobutyronitrile (AIBN). It was found that the number‐average molecular weight of polymers could reach about ten thousand with a narrow polydispersity index (PDI) of 1.4 in a few minutes, which was faster than other systems reported previously. But, at higher conversion, the molecular weight distribution of polymers became broad, and a bimodal distribution occurred. The macro‐initiators isolated from the former polymers with narrow PDI could be extended by polymerization with monomers by the addition of DDBSA. Furthermore, a proposed kinetic model demonstrated that the decay of the concentration of DDBSA would reduce the living polymer concentration and retard the growth of the polymers, which could be further propagated by the supplement of DDBSA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 42–49, 2005
Biological–synthetic hybrid block copolymers: Combining the best from two worlds
Authors: Klok Harm‐Anton 
Published: November 2004

AbstractAlthough biopolymers and synthetic polymers share many common features, each of these two classes of materials is also characterized by a distinct and very specific set of advantages and disadvantages. Combining biopolymer elements with synthetic polymers into a single macromolecular conjugate is an interesting strategy for synergetically merging the properties of the individual components and overcoming some of their limitations. This article focuses on a special class of biological–synthetic hybrids that are obtained by site‐selective conjugation of a protein or peptide and a synthetic polymer. The first part of the article gives an overview of the different liquid‐phase and solid‐phase techniques that have been developed for the synthesis of well‐defined, that is, site‐selectively conjugated, synthetic polymer–protein hybrids. In the second part, the properties and potential applications of these materials are discussed. The conjugation of biological and synthetic macromolecules allows the modulation of protein binding and recognition properties and is a powerful strategy for mediating the self‐assembly of synthetic polymers. Synthetic polymer–protein hybrids are already used as medicines and show significant promise for bioanalytical applications and bioseparations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1–17, 2005
Device model for poly(o‐methoxyaniline) field‐effect transistor
Authors: Bianchi R. F. , Onmori R. K. , Faria R. M. 
Published: November 2004

AbstractWe present a detailed study of the electric mechanism of a thin poly(o‐methoxyaniline) (POMA) field‐effect transistor. The device was prepared using Al‐Si/SiO2/(interdigitated gold lines array)/POMA structure as the gate electrode, insulating layer, source‐drain electrodes, and active layer, respectively. A model is presented for the electrical characteristics of such a device that encompasses the disordered properties of the POMA, the source‐drain electrical‐field dependence of hole mobility, and the carrier and mobility gradients in directions perpendicular to the polymer–oxide interface. The fittings of source‐drain current versus source‐drain voltage, having as parameters the gate voltage, is in good agreement with the experimental data, and the dependence of both the carrier saturation velocity and of the carrier mobility with the gate voltage are obtained. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 74–78, 2005
Preferential humoral immune response in prostate cancer to cellular proteins p90 and p62 in a panel of tumor‐associated antigens
Authors: Shi Fu‐Dong , Zhang Jian‐Ying , Liu Daorong , Rearden Ann , Elliot Max , Nachtsheim Dan , Daniels Tracy , Casiano Carlos A. , Heeb Mary Jo , Chan Edward K.L. , Tan Eng M. 
Published: November 2004

AbstractBACKGROUNDCytoplasmic p90 autoantigen was recently cloned from a cDNA expression library using serum antibody from a cancer patient. The humoral immune response to p90 in prostate cancer and benign prostatic hyperplasia (BPH) was examined.METHODSAn antigenic fragment of recombinant p90 protein and several other tumor‐associated antigens (TAAs) were used in ELISA and Western blotting to detect antibodies in sera from patients with prostate cancer, BPH, and other controls.RESULTSAutoantibodies to p90 were detected in 30.8% of 133 prostate cancer patients versus 1.5% in 68 BPH patients. When a selected panel of six TAAs including p90 were used for immunoscreening, the cumulative positive reactions in prostate cancer sera reached 92.5%, significantly higher than in BPH and other control sera. Antibodies to p90 showed the highest frequency in prostate cancer (30.8%), followed by antibodies to p62 (22.6%).CONCLUSIONSA panel of six selected TAAs was shown to have high sensitivity and specificity as immunodiagnostic markers in prostate cancer. © 2004 Wiley‐Liss, Inc.
Removal of sodium and potassium adducts using a matrix additive during matrix‐associated laser desorption/ionization time‐of‐flight mass spectrometric analysis of peptides
Authors: Leite John F. , Hajivandi Mahbod R. , Diller Thomas , Pope R. Marshall 
Published: November 2004

AbstractMonovalent cations often associate with peptides and proteins under mass spectrometry (MS) conditions, resulting in a discernable, but often misleading, adduct cluster pattern. These adduct cluster peaks reduce the signal intensity of specific peptide species by splitting the ion population into multiple mass peaks, suppressing the ionization of neighboring low‐abundance peaks, and interfering with identification of post‐translational modifications. Further, monovalent contaminants tend to form a distribution of matrix cluster peaks in matrix‐associated laser desorption/ionization time‐of‐flight (MALDI‐TOF) spectra causing interference and suppression in the mass range below 1400 Da. The most common method for reduction or elimination of adduct clusters is solid‐phase extraction via a pipette tip or spin column, which often leads to loss of low‐abundance peptide components. In this study we describe the use of a commercially available surfactant blend that markedly reduces the adduction of monovalent cations during peptide analysis by MALDI‐TOFMS. Copyright © 2004 John Wiley & Sons, Ltd.