bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryonic mouse testis development: Role of platelet derived growth factor (PDGF‐BB)
Authors: Ricci G. , Catizone A. , Galdieri M. 
Published: July 2004

AbstractPlatelet‐derived growth factors (PDGFs) are paracrine growth factors mediating epithelial–mesenchymal interactions and exerting multiple biological activities which include cell proliferation, motility, and differentiation. As previously demonstrated, PDGFs act during embryonic development and recently, by culturing male genital ridges, we have demonstrated that PDGF‐BB is able to support in vitro testicular cord formation. In the present paper, we report that PDGF‐BB is present during embryonic testis development and, in organ culture, induces cord formation although with reduced diameters compared with the cords formed in the genital ridges cultured in the presence of HGF. Moreover we have analyzed the roles exerted by this growth factor during the morphogenesis of the testis. We demonstrate by immunohistochemical experiments that PDGF‐BB and its receptors are synthesized by the male UGRs isolated from 11.5 and 13.5 dpc embryos and by Western blot that the factor is secreted in a biologically active form by testicular cells isolated from 13.5 dpc embryos. The biological roles of the factor have also been studied and we demonstrate that PDGF‐BB acts as a migratory factor for male mesonephric cells whose migration is a male specific event necessary for a normal testicular morphogenesis. In addition we demonstrate that during testicular development, PDGF‐BB induces testicular cell proliferation being in this way responsible for the increase in size of the testis. Finally we demonstrate that PDGF‐BB is able to reorganize dissociated testicular cells inducing the formation of large cellular aggregates. However the structures formed in vitro under PDGF‐BB stimulation never had a cord‐like morphology similar to the cord‐like structures formed in the presence of HGF (Ricci et al., 2002, Mech Dev 118:19–28), suggesting that this factor does not act as a morphogenetic factor during testicular development. All together the data presented in this paper demonstrate that PDGF‐BB and its receptors (α‐ and β‐subunits) are present during the crucial ages of embryonic mouse testis morphogenesis and indicate the multiple roles exerted by this factor during the development of the male gonad. © 2004 Wiley‐Liss, Inc.
Molecular identification of ERα‐positive breast cancer cells by the expression profile of an intrinsic set of estrogen regulated genes
Authors: Weisz Alessandro , Basile Walter , Scafoglio Claudio , Altucci Lucia , Bresciani Francesco , Facchiano Angelo , Sismondi Piero , Cicatiello Luigi , De Bortoli Michele 
Published: July 2004

AbstractEstrogens exert a key biological role in mammary gland epithelial cells and promote breast carcinogenesis and tumor progression. We recently identified a new large set of estrogen responsive genes from breast cancer (BC) cells by DNA microarray analysis of the gene expression profiles induced by 17β‐estradiol in ZR‐75.1 and MCF‐7 cells. The purpose of the present study was to test whether the expression pattern of hormone regulated genes from this set identifies estrogen receptor (ERα) positive, hormone responsive BC cells. To this aim, we carried out in silico metanalysis of ERα positive and ERα negative human BC cell line transcriptomes, focusing on two sets of 171 and 218 estrogen responsive genes, respectively. Results show that estrogen dependent gene activity in hormone responsive BC cells is significantly different from that of non‐responsive cells and, alone, allows to discriminate these two cellular phenotypes. Indeed, we have identified 61 genes whose expression profile specifically marks ERα positive BC cells, suggesting that this gene set may be exploited for phenotypic characterization of breast tumors. This possibility was tested with data obtained by gene expression profiling of BC surgical samples, where the ERα positive phenotypes were highlighted by the expression profile of a subset of 27 such hormone responsive genes and four additional BC marker genes, not including ERs. These results provide direct evidence that the expression pattern of a limited number of estrogen responsive genes can be exploited to assess the estrogen signaling status of BC cells both in vitro and ex‐vivo. © 2004 Wiley‐Liss, Inc.
MyoD induces the expression of p57Kip2 in cells lacking p21Cip1/Waf1: Overlapping and distinct functions of the two cdk inhibitors
Authors: Figliola Rocco , Maione Rossella 
Published: July 2004

AbstractThe myogenic factor MyoD induces the expression of the cdk inhibitor p21 to promote cell cycle withdrawal in differentiating myoblasts. Although the cdk inhibitor p57 is also highly expressed in skeletal muscle and is thought to redundantly control myogenesis, little is known about its regulation, that has been suggested to be independent of MyoD. Here we show, for the first time, that MyoD is capable to induce the expression of p57. Intriguingly, this ability is restricted to cells lacking p21, suggesting that the two cdk inhibitors may be expressed in different muscle cell lineages. We also suggest that the functions of p21 and p57 in myoblast cells are only in part redundant. In fact, while the two cdk inhibitors play a similar role in cells undergoing G1 arrest during MyoD‐induced differentiation, p57 does not replace p21 in cells escaping G1 arrest and undergoing MyoD‐induced apoptosis. This difference can be ascribed both to a different subcellular localization and to a differential ability of the two cdk inhibitors to interact with cell cycle regulators. © 2004 Wiley‐Liss, Inc.
In vivo transfection of the mouse vas deferens
Authors: Valenzuela Mario , Relloso Miguel , Esponda Pedro 
Published: June 2004

AbstractTo explore the possibility that specific characteristics of the epithelium of the male tract can be modified, transfections of the mouse vas deferens have been performed using in vivo injections of cationic DNA/liposome complexes. Gene transfer was done employing the reporter genes pEGFP‐C1 encoding Green Fluorescent Protein (GFP) and pCMV‐nls‐β encoding the nuclear β‐Galactosidase (β‐Gal). Foreign gene expression reached a maximum of 6.8% in the epithelial cells of the vas after treatment with the nuclear β‐Gal gene construction and of 13.3% after employing the GFP gene construction. Expression of the GFP gene appeared from one week up to three months following injection, and it appeared as patches of modified cells along the epithelium. Results from immunocytochemistry and Western Blotting support the conclusion that transfection of epithelial cells was achieved. We have also transfected the vas using gene constructions that express secretory proteins— specifically, the reporter system pSEAP‐control that expresses a secretory form of human placental alkaline phosphatase, and the pGFP‐Ctk‐37 that expresses a secretion form of GFP. In both cases, the fluids expressed from the transfected vas showed a significant increase of alkaline phosphatase activity after pSEAP transfection and the presence of GFP protein when pGFP‐Ctk‐37 gene construction was employed. Our results indicate that the vas can be transfected in vivo using liposomes as vectors of foreign genes and that the vas fluid contents can be modified. J. Exp. Zool. 293:532–540, 2002. © 2002 Wiley‐Liss, Inc.
‘Doing development’: the gap year, volunteer‐tourists and a popular practice of development
Authors: Simpson Kate 
Published: July 2004

AbstractOver the last ten years the gap year has become a popular and publicly recognized phenomenon. One of the most visible forms of this phenomenon has been the emergence of ‘third world’ volunteer‐tourism programmes, which seek to combine the hedonism of tourism with the altruism of development work. Such programmes make the practice of international development doable, knowable and accessible to young travellers. This paper seeks to critique the construction of this public face of development, while also asking, from a pedagogical perspective, what travelling participants learn about ‘the others’ they encounter on, and through, such programmes. Copyright © 2004 John Wiley & Sons, Ltd.
Contradiction and change? NGOs, schools and the public faces of development
Authors: Smith Matt 
Published: July 2004

AbstractThis paper addresses the contradictions that increasingly shape the public faces of development. Focusing on examples of the communication of development by International Non‐Governmental Organizations and UK schools, emphasis is placed on the social, political, economic and cultural dynamics that inform the public faces of development, and the tensions and dilemmas that these produce. The paper also highlights the need to look beyond the formal institutions and machineries of development to understand the contemporary production of development's public faces. Copyright © 2004 John Wiley & Sons, Ltd.
Distinguishing N‐oxide and hydroxyl compounds: impact of heated capillary/heated ion transfer tube in inducing atmospheric pressure ionization source decompositions
Authors: Peiris Dilrukshi M. , Lam Wing , Michael Steven , Ramanathan Ragu 
Published: June 2004

AbstractIn the pharmaceutical industry, a higher attrition rate during the drug discovery process means a lower drug failure rate in the later stages. This translates into shorter drug development time and reduced cost for bringing a drug to market. Over the past few years, analytical strategies based on liquid chromatography/mass spectrometry (LC/MS) have gone through revolutionary changes and presently accommodate most of the needs of the pharmaceutical industry. Among these LC/MS techniques, collision induced dissociation (CID) or tandem mass spectrometry (MS/MS and MSn) techniques have been widely used to identify unknown compounds and characterize metabolites. MS/MS methods are generally ineffective for distinguishing isomeric compounds such as metabolites involving oxygenation of carbon or nitrogen atoms. Most recently, atmospheric pressure ionization (API) source decomposition methods have been shown to aid in the mass spectral distinction of isomeric oxygenated (N‐oxide vs hydroxyl) products/metabolites. In previous studies, experiments were conducted using mass spectrometers equipped with a heated capillary interface between the mass analyzer and the ionization source. In the present study, we investigated the impact of the length of a heated capillary or heated ion transfer tube (a newer version of the heated capillary designed for accommodating orthogonal API source design) in inducing for‐API source deoxygenation that allows the distinction of N‐oxide from hydroxyl compounds. 8‐Hydroxyquinoline (HO‐Q), quinoline‐N‐oxide (Q‐NO) and 8‐hydroxyquinoline‐N‐oxide (HO‐Q‐NO) were used as model compounds on three different mass spectrometers (LCQ Deca, LCQ Advantage and TSQ Quantum). Irrespective of heated capillary or ion transfer tube length, N‐oxides from this class of compounds underwent predominantly deoxygenation decomposition under atmospheric pressure chemical ionization conditions and the abundance of the diagnostic [M + H − O]+ ions increased with increasing vaporizer temperature. Furthermore, the results suggest that in API source decompostion methods described in this paper can be conducted using mass spectrometers with non‐heated capillary or ion transfer tube API interfaces. Because N‐oxides can undergo in‐source decomposition and interfere with quantitation experiments, particular attention should be paid when developing API based bioanalytical methods. Copyright © 2004 John Wiley & Sons, Ltd.
Structure, reactivity and thermochemical properties of protonated lactic acid
Authors: Berruyer‐Penaud Florence , Bouchoux Guy , Payen Olivier , Sablier Michel 
Published: June 2004

AbstractThe protonation energetics of lactic acid (LA) were experimentally determined by the kinetic method including the entropy effect. The values (proton affinity, PA(LA) = 817.4 ± 4.3 kJ mol−1; protonation entropy, ΔS°p(LA) = −2 ± 5 J K−1 mol−1; gas‐phase basicity, GB(LA) = 784.5 ± 4.5 kJ mol−1) agree satisfactorily with computed G2(MP2) expectations (PA(LA) = 811.8 kJ mol−1; ΔS°p(LA) = −7.1 J K−1 mol−1; GB(LA) = 777.4 kJ mol−1). The fragmentation behaviour of protonated lactic acid (LAH+) is dominated by carbon monoxide loss followed by elimination of a water molecule. Direct dehydration of LAH+ is only a high‐energy process hardly competitive with the CO loss. A complete mechanistic scheme, based on MP2/6–31G* calculations, is proposed; it involves isomerization of the various protonated forms of LA and the passage through the ion–neutral complex between the 2‐hydroxypropyl acylium cation and a water molecule. Copyright © 2004 John Wiley & Sons, Ltd.
Temporal profile of ultrastructural changes in cortical neurons after a photochemical lesion
Authors: Andersson Benita , Wu Xingchen , Bjelke Börje , Syková Eva 
Published: July 2004

AbstractA photochemical lesion was induced in the right sensory motor cortex of rat brains. We examined at various time points the occurrence of different types of neuronal death with respect to a potential therapeutic window. The lesion appearance was documented by magnetic resonance imaging, and functional recovery was evaluated by behavioral tests showing recovery at 48 hr after lesioning. At 0.5, 1, 3, 6, 12, 24, 48, and 72 hr postlesion, cortical layers IV and V were examined by light and electron microscopy. Ultrastructural changes, which corresponded well to light microscopy findings, were found in both hemispheres. In the lesioned area, the neuropil appeared disorganized at 0.5 hr, and apoptotic and necrotic cell death was found at 0.5–3 hr. After 3 hr, the tissue was disintegrated. On the contralateral side, chromatin clumping appeared at 0.5–3 hr. At 3 hr, ruptured membranes were found, a sign of irreversible cell death. At 6–72 hr, the membranes were intact, and the chromatin was not clumped but heterogeneously distributed. The nuclei contained dispersed nucleoli at 48–72 hr. The morphology correlated well with magnetic resonance images and functional behavior. Our study demonstrates that a photochemical lesion is a useful model for studying morphological changes in injured cells. It results in a permanent infarction within 3 hr. In that the morphology on the contralateral side drastically changed between 3 and 6 hr, the cellular alterations at these time points might represent a break point at which cells either progress toward cell death or recover. © 2004 Wiley‐Liss, Inc.
Thermo‐Physical and Impact Properties of Epoxy Containing Epoxidized Linseed Oil, 2
Authors: Miyagawa Hiroaki , Mohanty Amar K. , Misra Manjusri , Drzal Lawrence T. 
Published: July 2004

AbstractSummary: Biobased neat epoxy materials containing epoxidized linseed oil (ELO) were processed with an amine curing agent. A defined amount of diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The thermophysical properties of the amine‐cured biobased neat epoxy were measured by dynamic mechanical analysis (DMA). The Izod impact strength increased with an increase in the amount of ELO added. The change in the Izod impact strength was correlated with the thermophysical properties measured by DMA.Relation between the Izod impact strength and loss factor for amine‐ and anhydride‐cured ELO‐containing epoxy resins.magnified imageRelation between the Izod impact strength and loss factor for amine‐ and anhydride‐cured ELO‐containing epoxy resins.
Thermo‐Physical and Impact Properties of Epoxy Containing Epoxidized Linseed Oil, 1
Authors: Miyagawa Hiroaki , Mohanty Amar K. , Misra Manjusri , Drzal Lawrence T. 
Published: July 2004

AbstractSummary: Biobased neat epoxy materials containing epoxidized linseed oil (ELO) were processed with an anhydride curing agent. A defined amount of the diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The selection of the DGEBF, ELO, and an anhydride curing agent resulted in an excellent combination, to provide a new biobased epoxy material showing high elastic modulus, high glass transition temperature, and high heat distortion temperature (HDT) with larger amounts of ELO. The Izod impact strength was almost constant while changing the amount of ELO. This is a promising result for future industrial applications in different engineering industries.The effect of changing ELO concentration of the anhydride‐cured neat epoxy on the storage modulus.magnified imageThe effect of changing ELO concentration of the anhydride‐cured neat epoxy on the storage modulus.
Bioconjugation of (CdSe)ZnS Quantum Dots Using a Genetically Engineered Multiple Polyhistidine Tagged Cohesin/Dockerin Protein Polymer
Authors: Ding Shi‐You , Rumbles Garry , Jones Marcus , Tucker Melvin P. , Nedeljkovic Jovan , Simon Martha N. , Wall Joseph S. , Himmel Michael E. 
Published: July 2004

AbstractSummary: We have constructed bioconjugates consisting of genetically modified cohesin/dockerin protein polymers combined with (CdSe)ZnS colloidal quantum dots. This recombinant protein contains fusions of Clostridium thermocellum cellulosomal cohesin and dockerin domains and a C‐terminal 6×‐histidine tag. These unique cohesin/dockerin monomeric building blocks (ca. 60 kDa) were allowed to self‐assemble, yielding oligomers and polymers, which were subsequently characterized by high‐pressure size exclusion chromatography (HPSEC). The C‐terminal 6×‐His tags from each monomer facilitate binding to the quantum dot surface chemistry while mix the protein polymers with water‐soluble QDs at neutral pH. Using HPSEC, we were able to fractionate the reaction mixture into two major distributions of bioconjugate species. Scanning transmission electron microscopy (STEM) and photoluminescence spectroscopy (PL) were employed to characterize the components from these chromatographic fractions. The fraction containing the larger bioconjugates contained clusters of quantum dots surrounded by protein polymers with an estimated radius of 190 ± 30 Å and an apparent molecular weight of 8 000 ± 3 000 kDa. The STEM images from the fraction containing the smaller species were amenable to detailed analysis and graphical simulation that revealed species containing one, two, or three quantum dots surrounded by 10, 15, or 18 protein monomers, respectively. Our data demonstrate strong binding coefficients not only between the protein monomers to form polymers, but also with the (CdSe)ZnS colloidal quantum dots and thus provides a method of producing stable, water‐soluble luminescent quantum dot bioconjugates. PL spectroscopic analysis shows that the samples from both chromatographic fractions have strong excitonic emission with a peak at ca. 2.2 eV (562 nm).STEM images of cohesin/dockerin protein polymer‐QD conjugates from the HPSEC elution peak. A represents a typical STEM image 512 × 512 nm scanning field showing the conjugates containing 1, 2, and 3 QDs with 10, 15, and 18 protein monomers surrounded, respectively.magnified imageSTEM images of cohesin/dockerin protein polymer‐QD conjugates from the HPSEC elution peak. A represents a typical STEM image 512 × 512 nm scanning field showing the conjugates containing 1, 2, and 3 QDs with 10, 15, and 18 protein monomers surrounded, respectively.
Relaxation of Copolymeric Dendrimers Built from Alternating Monomers
Authors: Satmarel Cristian , Gurtovenko Andrey A. , Blumen Alexander 
Published: July 2004

AbstractSummary:In this study we extend our previous work concerning the Rouse dynamics of linear alternating copolymers (Macromolecules2003,36, 486) to tree‐like structures and focus on copolymeric dendrimers built from monomers of two kindsAandB; as before, we let the monomers differ in their interaction with the solvent. In the framework of generalized Gaussian structures (GGS), we consider alternating arrangements of monomers over the dendritic structures. We develop a semi‐analytical method to determine for such structures (of arbitrary functionality,f, and number of generations,g), the eigenfrequencies (relaxation times). The method allows us to compute readily the storage, [G′(ω)] and the loss, [G″(ω)] moduli. These quantities show a multitude of features which mainly depend on the difference in the mobilities, or, equivalently, in the friction coefficientsζAandζBof theA‐ andB‐beads. These features range from the presence of large plateau‐type regions in [G′(ω)] to the appearance of double‐peaks in [G″(ω)]. In contrast to linear alternating copolymers, the behavior of the dynamic moduli of copolymeric systems with dendritic topology can shed light into their composition, i.e. into the relative numbers ofA‐ andB‐beads. We discuss these aspects in view of their experimental relevance.A system under study: a dendrimer of third generation (g = 3) with functionalityf = 3, composed of alternating beads.imageA system under study: a dendrimer of third generation (g = 3) with functionalityf = 3, composed of alternating beads.
Biocoating of Electropolished and Ultra‐Hydrophilic Titanium and Cobalt Chromium Molybdenum Alloy Surfaces with Proteins
Authors: Chatzinikolaidou M. , Laub M. , Rumpf H. , Jennissen H. P. 
Published: June 2004

AbstractBone morphogenetic proteins (BMPs) play a decisive role in bone development and osteogenesis. In the past they have been the subject of widespread research and clinical trials as stimulants of bone growth. Although recently recombinant human BMP‐2 (rhBMP‐2) has been chemically immobilized on implant surfaces leading to enhanced bone growth and accelerated integration in vivo, the non‐covalent immobilization of proteins on metal surfaces is still poorly understood, since the oxide layers on metals like titanium, stainless steel or cobalt chromium alloys are poor adsorbents of proteins. Protein binding surfaces could either be generated by linking ionic groups (ion‐exchange surface) or by coupling hydrophobic residues (hydrophobic interacting surface, HIS) to the surface. In this paper the preparation of protein adsorbing surfaces on titanium and cobalt chromium molybdenum alloy for the adsorption of rhBMP‐2 and ubiquitin will be described. rhBMP‐2 and ubiquitin are bound extremely tight to surfaces containing propyl or hexyl groups of a certain surface concentration and are slowly released over a range of at least 24–100 days making such surfaces applicable as long‐term drug delivery devices for enhancing bone growth or implant integration.
Contact allergies to metal components of the 316 L steel in patients with coronary heart disease
Authors: Hillen U. , Haude M. , Erbel R. , Goos M. 
Published: June 2004

AbstractIn‐stent restenosis is a complication which impairs the success of coronary stenting. Recently it was supposed that a delayed hypersensitivity reaction to nickel and molybdenum might be one of the triggering factors in in‐stent restenosis. We have performed a retrospective analysis of the data collected in our centre with respect to this hypothesis. Altogether 20 patients were investigated (13 male, 7 female). Patch tests were performed with the standard series of the German Contact Dermatitis Research Group and a metal series containing the metal components of the 316 L stainless steel. A positive patch test reaction to nickel was observed in 2 (10.0%) patients, one of these patients had an in‐stent restenosis, the other had not. None of the patients showed a sensitization to the other metals. Restenoses were predominantly observed in patients with a negative patch test reaction to nickel (6/18 patients). Although it cannot be excluded that metal allergy may play a role in the restenosis process in coronary stenting there is at the moment little evidence for it.