bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Peptide‐Cyclodextrin Hybrid System Capable of Detecting Guest Molecules Utilizing Fluorescence Resonance Energy Transfer
Authors: Yana Dewi , Takahashi Tsuyoshi , Mihara Hisakazu , Ueno Akihiko 
Published: February 2004

AbstractSummary: A cyclodextrin‐peptide hybrid bearing coumarin and fluorescein on the peptide side chain has been designed and synthesized as a novel chemosensor molecule utilizing fluorescence resonance energy transfer (FRET). Inclusion of coumarin into β‐cyclodextrin protects this system against fluorescent quenching, so that FRET occurs though donor and acceptor moieties nearby. FRET is diminished upon the addition of various guest compounds, suggesting that this system is useful for detecting molecules in aqueous solution.A cyclodextrin‐peptide hybrid bearing coumarin and fluorescein on the peptide side chain.imageA cyclodextrin‐peptide hybrid bearing coumarin and fluorescein on the peptide side chain.
Preparation of Stable Colloidal Crystals and Macroporous Materials Using Diazoresin as a Thermosetting Agent
Authors: Cong Hailin , Cao Weixiao 
Published: February 2004

AbstractSummary: Two kinds of stable colloidal crystals have been prepared from polymeric or SiO2 colloids in the presence of diazoresin (DR) as a thermosetting agent combining thermal treatment. Following the decomposition of N groups of DR under heating, the ionic bonds between the DR molecules and colloids change to covalent bonds and the colloidal crystals become very stable toward ultrasonic washing. The colloids were then removed by tetrahydrofuran (THF) in the case of organics or by hydrofluoric acid (HF) for the inorganics to leave the macroporous DR materials.Reactions between the DR molecules and the colloids during thermal treatment.imageReactions between the DR molecules and the colloids during thermal treatment.
Cationic Spherical Polyelectrolyte Brushes as Nanoreactors for the Generation of Gold Particles
Authors: Sharma Geeta , Ballauff Matthias 
Published: February 2004

AbstractSummary: If long polyelectrolyte chains are attached densely to colloidal latex particles, a spherical polyelectrolyte brush results. These spherical polyelectrolytes are dispersed in water and carry a high charge. We demonstrate that these systems can be used to immobilize ions of heavy metals, such as gold, as counter‐ions. Reduction of these ions leads to metallic nanoparticles. In this way the brush layer attached to the surface of the particles becomes a “nanoreactor” that may be used for chemical conversions of the metal ions. We show that the reduction of AuCl ions within these nanoreactors leads to well‐defined and rather monodisperse gold nanoparticles that are attached to the surface of the core. A stable dispersion of polymeric core particles with attached nanoparticles results. All results reported here suggest that chemical reactions of ions immobilized in spherical polyelectrolyte brushes provide a new route to composite particles of inorganic and organic materials.Transmission electron micrograph of gold particles on a core‐shell system.imageTransmission electron micrograph of gold particles on a core‐shell system.
Preparation, Structure, and Properties of Starch/Rubber Composites Prepared by Co‐Coagulating Rubber Latex and Starch Paste
Authors: Wu You‐Ping , Ji Mei‐Qin , Qi Qing , Wang Yi‐Qing , Zhang Li‐Qun 
Published: February 2004

AbstractSummary: Several rubber/starch composites in which the starch particles are in an amorphous state and are smaller than 1 μm, prepared by directly mixing and co‐coagulating rubber latex and starch paste, exhibit higher hardness, stress at 100%, tensile strength, and tear strength relative to the corresponding rubber/starch composites prepared by direct blending.TEM micrograph of starch/SBR composite.imageTEM micrograph of starch/SBR composite.
Atom Transfer Radical Polymerization of N‐Isopropylacrylamide
Authors: Masci Giancarlo , Giacomelli Laura , Crescenzi Vittorio 
Published: February 2004

AbstractSummary: Controlled polymerization of N‐isopropylacrylamide (NIPAAM) was achieved by atom transfer radical polymerization (ATRP) using ethyl 2‐chloropropionate (ECP) as initiator and CuCl/tris(2‐dimethylaminoethyl)amine (Me6TREN) as a catalytic system. The polymerization was carried out in DMF:water 50:50 (v/v) mixed solvent at 20 °C. The first order kinetic plot was linear up to 92% conversion. Controlled molecular weights up to 2.2 × 104 and low polydispersities (1.19) were obtained. The living character of the polymerization was also demonstrated by self‐blocking experiments. Block copolymers with N,N‐dimethylacrylamide (DMAAM) and 3‐sulfopropyl methacrylate (SPMA) were successfully prepared.Molecular weights and polydispersities of polyNIPAAM versus NIPAAM conversion for two different degrees of polymerization.imageMolecular weights and polydispersities of polyNIPAAM versus NIPAAM conversion for two different degrees of polymerization.
Gelation Studies on a Radical Chain Cross‐Linking Copolymerization Process: Comparison of the Critical Exponents Obtained by Dynamic Light Scattering and Rheology
Authors: Richter Sven , Boyko Volodymyr , Schröter Klaus 
Published: February 2004

AbstractSummary:The sol–gel transition of a radical chain cross‐linking copolymerization system [N‐vinylcaprolactam/2‐hydroxylethyl methacrylate/allyl methacrylate] has been studied using in situ time‐resolved dynamic light scattering (DLS) and in situ rheology. A critical dynamic behavior was observed near the sol–gel transition, which was characterized by the presence of a power‐law spectra over three decades in the time–intensity correlation functiong2(t) − 1 ∼ t−μand over two decades in the oscillatory shear experimentG′(ω) ∼ G″(ω) ∼ ωn. A comparison of the obtained critical exponentsμ ≈ 0.62 andn ≈ 0.75 was made. The theory predicts a relationship between these exponents, but up to now no experimental comparison has been done. The experimental results favor the percolation model, with a fractal dimensiondfof the gel clusters of 1.67.Double‐logarithmic plot of time–intensity correlation functionsg2(t) − 1 versus the delay timet.imageDouble‐logarithmic plot of time–intensity correlation functionsg2(t) − 1 versus the delay timet.
Cover Picture: Macromol. Rapid Commun. 4/2004
Authors: Richter Sven , Boyko Volodymyr , Schröter Klaus 
Published: February 2004

Cover: The sol‐gel transition is a very important critical phenomenon. The gelation of a radical chain cross‐linking copolymerization system has been studied by using in situ time‐resolved dynamic light scattering and in situ rheology. Critical dynamical behavior was observed near the sol‐gel transition, which is characterized by the presence of power‐law spectra in the oscillatory shear experiment (upper left figure of the cover picture) and in the time‐intensity correlation function (lower right figure of the cover picture). A experimental comparison of the critical exponents obtained from both methods was done for the first time.Further details can be found in the Communication by S. Richter,* V. Boyko, and K. Schröter on page 542.
Crossregulation of NF‐κB by the APC/GSK‐3β/β‐catenin pathway
Authors: Deng Jiong , Xia Weiya , Miller Stephanie A. , Wen Yong , Wang Hong‐Ying , Hung Mien‐Chie 
Published: February 2004

AbstractGlycogen synthase kinase‐3β (GSK‐3β) and adenomatous polyposis coli (APC) play an important role in the regulation of β‐catenin. Inhibition of or defects in their functions can lead to activation of β‐catenin. β‐catenin has been recently found to interact with and inhibit nuclear factor kappa B (NF‐κB). However, the regulatory roles of GSK‐3β/APC on the NF‐κB signaling pathway are unknown because of their diverse effects. In this study, we investigated whether GSK‐3β/APC might regulate NF‐κB activity through β‐catenin. We found that inhibition of GSK‐3β suppressed NF‐κB activity, whereas reexpression of APC restored NF‐κB activity in APC mutated cells. The regulatory effects were through β‐catenin because depletion of β‐catenin with small interfering RNA (siRNA) in the same systems reversed the effects. The regulatory relationship was further supported by the analysis of primary breast tumor tissues in vivo in which NF‐κB target TRAF1 was inversely correlated with activated β‐catenin. Thus, APC/GSK‐3β, through β‐catenin, may crossregulate NF‐κB signaling pathway. © 2004 Wiley‐Liss, Inc.
Relationship between the radiosensitizing effect of wortmannin, DNA double‐strand break rejoining, and p21WAF1 induction in human normal and tumor‐derived cells
Authors: Mirzayans Razmik , Pollock Scott , Scott April , Enns Louise , Andrais Bonnie , Murray David 
Published: February 2004

AbstractWortmannin (WM) is a potent inhibitor of the catalytic sub‐unit of DNA‐PK, which is involved in one pathway of DNA double‐strand break (DSB) rejoining, and of ATM, which functions upstream in the p53 signaling pathway. WM is known to be an efficient radiosensitizer in a variety of mammalian cell types, to inhibit DSB rejoining following exposure to supralethal doses (≥30 Gy) of ionizing radiation, and to abrogate the induction of p53 at early times after radiation exposure. We report here that WM is a more effective radiosensitizer in A549 human lung carcinoma cells than in normal human fibroblasts (NHFs). In addition, WM strongly inhibits DSB rejoining in A549 cells exposed to relatively low doses (e.g., 10 Gy) of ionizing radiation, without having any detectable effect in NHFs. We further demonstrate that WM significantly potentiates the induction of p21WAF1, a p53‐regulated gene that encodes for a key mediator of cell‐cycle/growth arrest, when determined at late times (e.g., 24 h) after irradiation. This late WM‐dependent potentiation of p21WAF1 induction following radiation exposure is observed in NHFs and in the p53 wild‐type tumor cell lines A549, A172, and SKNSH, but not in the p53‐deficient tumor cell lines DLD‐1, HeLa, and SKNSH‐E6. We conclude that: (i) inhibition of DSB rejoining by WM may be an important contributor to its radiosensitizing effect in A549 cells but not in NHFs; and (ii) radiosensitization of p53‐proficient human cells by WM may in part be associated with the delayed induction of p21WAF1, which can lead to a sustained growth‐arrested phenotype resembling senescence. © 2004 Wiley‐Liss, Inc.
Inactivation of the cyclin‐dependent kinase inhibitor 2A (CDKN2A) gene in squamous cell carcinoma of the larynx
Authors: Smigiel Robert , Sasiadek Maria , Krecicki Tomasz , Ramsey David , Jagielski Jozef , Blin Nikolaus 
Published: February 2004

AbstractDefects in the system controlling the cell cycle can lead an increased proliferation of cancer cells. The aim of our study was to analyze the relationship between genetic changes leading to inactivation of the CDKN2A gene and subsequent alteration of protein expression in squamous cell cancer of the larynx (SCCL) in connection with the clinical and histopathological course of the disease. Analysis was carried out on DNA isolated from the blood and primary larynx cancer cells of 62 patients. To investigate loss of heterozygosity (LOH), PCR fragment analysis was applied. The size and quantity of fluorescent PCR products were evaluated in an automated sequencer. Specific chemical methylation with sodium bisulfite in a sequential PCR reaction (MSP) was applied to analyze promoter methylation. Cancer tissue sections served to determine the level of protein expression with immunohistochemical (IHC) staining and commercial antibodies. LOH at the CDKN2A locus was observed in 55.35% of the informative cases. Aberrant methylation was found in 37.5% and a decreased level of protein expression observed in 45% of all informative cases. Whenever P16 expression was decreased, LOH and promoter hypermethylation at CDKN2A were observed with a frequency of 73.33% and 80.95%, respectively (Fisher's test, P < 0.005). Sixty‐nine percent of G3 tumors had at least one genetic alteration at CDKN2A, compared with 40.9% of G1 cancers. The results indicate that CDKN2A inactivation played a significant role in the development of squamous cell carcinoma of the larynx. © 2004 Wiley‐Liss, Inc.
Caspase‐8 levels affect necessity for mitochondrial amplification in death ligand‐induced glioma cell apoptosis
Authors: Knight Melissa J. , Riffkin Christopher D. , Ekert Paul G. , Ashley David M. , Hawkins Christine J. 
Published: February 2004

AbstractFifty percent of high‐grade glioma patients die within a year of diagnosis and less than two percent survive five years postdiagnosis. Elucidating apoptosis signaling pathways may assist in designing better adjuvant therapies. Preliminary characterizations suggested that glioma cells may either employ mitochondrial‐independent or ‐dependent death receptor‐induced apoptotic pathways, characteristic of cells termed type I and type II, respectively. In the present study, we generated panels of clonal transfectants overexpressing various levels of Bcl‐2, in two parental glioma cell lines. These cells were used to explore molecular factors determining the necessity for mitochondrial amplification of death receptor signaling. Moderate Bcl‐2 expression was sufficient to render one glioma cell line (D270) resistant to apoptosis induced by Fas ligand or TRAIL, consistent with these cells being type II. However, expression of even very high levels of Bcl‐2 in a second line (D645) did not affect death ligand sensitivity, indicative of a type I phenotype. D270 cells expressed much less caspase‐8 protein than D645 cells. Enforced overexpression of caspase‐8 (or cytoplasmic Diablo/Smac) in D270 cells overcame Bcl‐2 inhibition of death ligand‐induced apoptosis, converting them from type II to type I. This indicates that caspase‐8 levels can influence the requirement for mitochondrial involvement in death receptor apoptotic signaling in glioma cells. © 2004 Wiley‐Liss, Inc.
Tools for anti‐inflammatory drug design: In vitro models of leukocyte migration
Authors: Frow Emma K. , Reckless Jill , Grainger David J. 
Published: February 2004

AbstractInhibiting leukocyte recruitment is now a major focus in the design of novel anti‐inflammatory drugs. Following the identification of lead compounds from conventional high‐throughput screens using appropriate receptors or enzymes, it is important to validate the action of the compounds in a suitable in vitro model of leukocyte migration. Here, we review a range of different experimental approaches to modelling leukocyte migration, and identify the multi‐well filter migration assay as the best compromise between the amount of resources required to screen multiple compounds and the amount of information gained about the effects of the compounds on cell movement behavior. However, there are pitfalls in the interpretation of data obtained using the multi‐well filter migration assay, which arise from the imperfect correlation between the number of cells undergoing migration and the inhibitory activity of the test substances. We examine a number of such pitfalls and provide practical approaches to mitigate these problems as far as possible. We recommend a general strategy for screening inhibitors of cell migration using in vitro functional assays. While being more resource intensive than surrogate measures such as calcium flux, functional approaches nevertheless provide superior correlations with anti‐inflammatory activity in vivo. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 276–298, 2004
Liposome/water lipophilicity: Methods, information content, and pharmaceutical applications
Authors: van Balen Georgette Plemper , Martinet Catherine a Marca , Caron Giulia , Bouchard Géraldine , Reist Marianne , Carrupt Pierre‐Alain , Fruttero Roberta , Gasco Alberto , Testa Bernard 
Published: February 2004

AbstractThis review discusses liposome/water lipophilicity in terms of the structure of liposomes, experimental methods, and information content. In a first part, the structural properties of the hydrophobic core and polar surface of liposomes are examined in the light of potential interactions with solute molecules. Particular emphasis is placed on the physicochemical properties of polar headgroups of lipids in liposomes. A second part is dedicated to three useful methods to study liposome/water partitioning, namely potentiometry, equilibrium dialysis, and 1H‐NMR relaxation rates. In each case, the principle and limitations of the method are discussed. The next part presents the structural information encoded in liposome/water lipophilicity, in other words the solutes' structural and physicochemical properties that determine their behavior and hence their partitioning in such systems. This presentation is based on a comparison between isotropic (i.e., solvent/water) and anisotropic (e.g., liposome/water) systems. An important factor to be considered is whether the anisotropic lipid phase is ionized or not. Three examples taken from the authors' laboratories are discussed to illustrate the factors or combinations thereof that govern liposome/water lipophilicity, namely (a) hydrophobic interactions alone, (b) hydrophobic and polar interactions, and (c) conformational effects plus hydrophobic and ionic interactions. The next part presents two studies taken from the field of QSAR to exemplify the use of liposome/water lipophilicity in structure–disposition and structure–activity relationships. In the conclusion, we summarize the interests and limitations of this technology and point to promising developments. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 299–324, 2004
Melanocortin ligands: 30 years of structure–activity relationship (SAR) studies
Authors: Holder Jerry Ryan , Haskell‐Luevano Carrie 
Published: February 2004

AbstractThe challenge of peptide and peptidomimetic research is the development of methods and techniques to improve the biological properties of native peptides and to convert peptide ligands into non‐peptide compounds. Improved biological properties of peptides includes enhancement of stability, potency, and receptor selectivity, for both in vivo and in vitro applications. The design of a ligand with specific activity and desired biological properties is a complex task, and, to accomplish this objective, knowledge about putative interactions between a ligand and the corresponding receptor will be valuable. This includes interactions for both the binding and signal transduction processes. Structure–activity relationship (SAR) studies involve systematic modification of a lead peptide and are designed to provide insight into potential interactions involved in the formation of the ligand–receptor complex. It is desirable to have knowledge about both favorable and unfavorable processes that may occur in putative ligand–receptor interactions that result in either receptor stimulation or inhibition. Herein, we discuss various SAR studies that have involved melanocortin peptides over three decades and the information these studies have provided to the melanocortin field. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 325–356, 2004
Peptide‐based radiopharmaceuticals: Future tools for diagnostic imaging of cancers and other diseases
Authors: Okarvi S.M. 
Published: February 2004

AbstractAn Erratum has been published for this article in Medicinal Research Reviews 2004;24:685–686.Small synthetic receptor‐binding peptides are the agents of choice for diagnostic imaging and radiotherapy of cancers due to their favorable pharmacokinetics. Molecular modification techniques permit the synthesis of a variety of bioactive peptides with chelating groups, without compromising biological properties. Various techniques have been developed that allow efficient and site‐specific labeling of peptides with clinically useful radionuclides such as 99mTc, 123I, 111In, and 18F. Among them, 99mTc is the radionuclide of choice because of its excellent chemical and imaging characteristics. Recently, many 99mTc‐labeled peptides have proven to be useful imaging agents. Beside 99mTc‐labeled peptides, several peptides radiolabeled with 111In and 123I have been prepared and characterized. In addition, 18F‐labeled peptides hold clinical potential due to their ability to quantitatively detect and characterize a variety of human diseases using positron‐emission tomography. The availability of this wide range of peptides labeled with different radionuclides offers multiple diagnostic and therapeutic applications. Various receptors are over‐expressed in particular tumor types and peptides binding to these receptors can be used to visualize tumor lesions scintigraphically. Thus, radiolabeled peptides have potential use as carriers for the delivery of radionuclides to tumors, infarcts, and infected tissues for diagnostic imaging and radiotherapy. Many radiolabeled peptides are currently under investigation to determine their potential as imaging agents. These peptides are designed mainly for thrombus, tumor, and infection/inflammation imaging. This article presents recent developments in small synthetic peptides for imaging of thrombosis, tumors, and infection/inflammation. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 357–397, 2004
Expression of the bovine aromatase cytochrome P450 gene (Cyp19) is primarily regulated by promoter 2 in bovine follicles and by promoter 1.1 in corpora lutea
Authors: Lenz Solvig , Pöhland Ralf , Becker Frank , Vanselow Jens 
Published: February 2004

AbstractFollicular development and differentiation are closely associated with increasing steroidogenesis. During the present study transcript concentration of Cyp19, Cyp11A1, and 3β‐hydroxysteroid dehydrogenase delta (3β‐HSD) encoding the steroidogenic enzymes P450arom, P450SCC, and 3β‐HSD were determined by real‐time PCR in bovine granulosa cells (GC) as potential markers for follicular differentiation. Ovaries were collected from a local abattoir (experiment 1) and from synchronized animals at day 4 of estrus cycle (experiment 2). To study effects of luteinization, steroidogenic transcripts were also quantified in corpora lutea (CL) 4 and 20 days after fertilization. In most follicles, all three steroidogenic transcripts were detected, however, at very different concentration. Expression of 3β‐HSD and Cyp11A1 was highly significantly co‐regulated and showed a significant correlation with follicular size. Contrary, Cyp19 expression was extremely variable even in follicles of similar size. Cyp19 transcripts were derived predominantly from promoter P2 and less abundant from promoters P1.1 and P1.5. After luteinization, the concentration of 3β‐HSD and Cyp11A1 transcripts increased (75‐fold and fivefold, respectively) whereas the Cyp19 transcript level dropped (160‐fold). Residual Cyp19 transcripts in CL were almost exclusively derived from P1.1. The data indicate that Cyp19 expression in GC is predominantly regulated by P2 and to a minor extend by P1.1, whereas P1.1 is almost exclusively responsible for residual Cyp19 expression in CL. Correlation analyses suggest that the expression of 3β‐HSD and Cyp11A1 primarily depend on the size of follicles whereas the concentration of P2 derived Cyp19 transcripts in GC is a marker for follicular differentiation towards selection and dominance. Mol. Reprod. Dev. 67: 406–413, 2004. © 2004 Wiley‐Liss, Inc.