bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Deposition of Platinum Nanoparticles on Carbon: A Study by Standard and Anomalous X‐ray Diffraction
Authors: Adora Sébastien , Simon Jean Paul , Soldo‐Olivier Yvonne , Faure René , Chaînet Eric , Durand Robert 
Published: August 2004

AbstractThis paper is devoted to an alternative method to characterize platinum nanoparticles: X‐ray powder diffraction with synchrotron radiation in classical and anomalous dispersion modes. We could straightforwardly determine the mean diameter and the surface concentration of carbon‐supported platinum nanoparticles, even down to diameters of 2–3 nm and catalyst amounts of 0.03 mg cm−2. We could study early stages of the formation of electrochemically prepared platinum nanoparticles from [PtCl4]2− species preadsorbed on carbon inside a carbon–Nafion layer, to obtain a fuel‐cell electrode. Our X‐ray diffraction (XRD) results demonstrate that, provided the superficial concentration is not too high, new and smaller particles appear for each current pulse, since there is not any strong nucleation limitation for the high overvoltages obtained. Hydrogen evolution becomes the main electrochemical phenomenon on particles of sufficient size and it explains the noteworthy size limitation. Better yields of Pt metal are obtained for smaller current densities and longer times: the rate‐determining step is then not electrochemical, but chemical or related to superficial diffusion.
Ethanol Decomposition: CC Cleavage Selectivity on Rh(111)
Authors: Vesselli Erik , Baraldi Alessandro , Comelli Giovanni , Lizzit Silvano , Rosei Renzo 
Published: August 2004

AbstractEthanol adsorption, desorption and decomposition on Rh(111) have been studied by X‐ray photoelectron spectroscopy and temperature‐programmed desorption experiments. The evolution of the C 1s and O 1s core level spectra was monitored as a function of ethanol exposure and surface temperature. Ethanol adsorption at 90 K results in two nonequivalent ethanol‐adsorbed species at low surface coverage, while a third species—related to multilayer formation—appears after longer exposures. Upon surface annealing, ethanol undergoes both desorption and dissociation, thus creating intermediate surface species which further decompose to hydrogen, carbon monoxide and atomic carbon. Our results clearly show that CC bond cleavage is the preferential dissociation channel, while CO bond scission is not observed. Calculations performed within the framework of the unity bond index—quadratic exponent potential model, have been used to test and compare different competing dissociation channels, providing an estimate of adsorption energies and dissociation barriers.
Adsorption of Amyloid Beta (1‐40) Peptide to Phosphatidylethanolamine Monolayers
Authors: Maltseva Elena , Brezesinski Gerald 
Published: August 2004

AbstractThe aggregation of soluble, nontoxic amyloid β (Aβ) peptide to β‐sheet containing fibrils is assumed to be a major step in the development of Alzheimer's disease. Interactions of Aβ with neuronal membranes could play a key role in the pathogenesis of the disease. Herein, we study the adsorption of synthetic Aβ peptide to DPPE and DMPE monolayers (dipalmitoyl‐ and dimyristoylphosphatidylethanolamine). Both lipids exhibit a condensed monolayer state at 20 °C and form a similar lattice. However, at low packing densities (at large area per molecule), the length of the acyl chains determines the phase behavior, therefore DPPE is fully condensed whereas DMPE exhibits a liquid‐expanded state with a phase transition at approximately 5–6 mN m−1. Adsorption of Aβ to DPPE and DMPE monolayers at low surface pressure leads to an increase of the surface pressure to approximately 17 mN m−1. The same was observed during adsorption of the peptide to a pure air–water interface. Grazing incidence X‐ray diffraction (GIXD) experiments show no influence of Aβ on the lipid structure. The adsorption kinetics of Aβ to a DMPE monolayer followed by IRRAS (infrared reflection absorption spectroscopy) reveals the phase transition of DMPE molecules from liquid‐expanded to condensed states at the same surface pressure as for DMPE on pure water. These facts indicate no specific interactions of the peptide with either lipid. In addition, no adsorption or penetration of the peptide into the lipid monolayers was observed at surface pressures above 30 mN m−1. IRRAS allows the measurement of the conformation and orientation of the peptide adsorbed to the air–water interface and to a lipid monolayer. In both cases, with lipids at surface pressures below 20 mN m−1 and at the air–water interface, adsorbed Aβ has a β‐sheet conformation and these β‐sheets are oriented parallel to the interface.
The State of the Iron Promoter in Tungstated Zirconia Catalysts
Authors: Carrier Xavier , Lukinskas Povilas , Kuba Stefan , Stievano Lorenzo , Wagner Friedrich E. , Che Michel , Knözinger Helmut 
Published: August 2004

AbstractThe activity and selectivity of tungstated zirconia (WZ) for the conversion of n‐ into isopentane are dramatically enhanced when the catalyst is modified with Pt and Fe. The state of iron in these catalysts was hitherto only poorly characterized. Therefore, in the present work we investigated the structural and electronic properties of iron in WZ catalysts containing 1 wt % Pt and 1 wt % Fe2O3, by a combination of spectroscopic techniques, namely X‐ray absorption spectroscopy (XAS), in situ electron paramagnetic resonance (EPR), and Mössbauer spectroscopy.In the oxidized catalyst, iron is present as FeIII and predominantly forms a surface solid solution in which the isolated FeIII ions are located in a distorted octahedral environment. A small amount of the total iron (around 10 %) is present in the form of small iron oxide particles. Both iron species can be reduced in H2 and then easily reoxidized on exposure to air at room temperature. We infer that the promoter action of iron in these catalysts is intimately related to its redox properties and specifically affects the dehydrogenation activity of the materials.
The Excited‐State Dynamics of Phycocyanobilin in Dependence on the Excitation Wavelength
Authors: Dietzek Benjamin , Maksimenka Raman , Hermann Gudrun , Kiefer Wolfgang , Popp Jürgen , Schmitt Michael 
Published: August 2004

AbstractThe primary light‐induced processes of phycocyanobilin were studied by means of transient‐grating spectroscopy, whereby the excitation wavelength was varied over the spectral region of the ground‐state absorption. On the basis of the results obtained, both the rate of the photoreaction in phycocyanobilin and the ratio of the decay of different excited‐state species via two decay channels depend on the excitation wavelength. Furthermore, the formation of the photoreaction product is also dependent on the pump color. These data support a recently established model for the primary photoprocesses in phycocyanobilin. In addition, phycocyanobilin protonated at the basic pyrrolenine‐type nitrogen atom was included in the transient absorption study. The decay behavior was found to be almost unchanged when compared with the unprotonated form, and this suggests that protonation of the tetrapyrrole ring structure has no effect on the overall photochemistry.
Noniterative Biexponential Fluorescence Lifetime Imaging in the Investigation of Cellular Metabolism by Means of NAD(P)H Autofluorescence
Authors: Niesner Raluca , Peker Bülent , Schlüsche Peter , Gericke Karl‐Heinz 
Published: August 2004

AbstractThe cofactors NADH and NADPH, hereafter NAD(P)H [NAD(P)=nicotinamide adenine dinucleotide (phosphate)], belong to the principal endogenous indicators of energetic cellular metabolism. Since the metabolic activity of cells is given by the ratio between the concentrations of free and protein‐bound NAD(P)H, the development of autofluorescence techniques which accurately measure the modifications to this ratio is particularly significant. Hitherto the methods applied in the monitoring of cellular metabolism have provided either imprecise results, due to interference of the NAD(P)H signal by perturbing factors, or they have required a complicated internal calibration. We employ biexponential fluorescence lifetime imaging (FLIM) in order to discriminate between the free and protein‐bound NAD(P)H without any previous calibration. Thus, we have obtained directly, and for the first time, a high‐resolution map of cellular metabolism, that is, an image of the contribution of the protein‐bound NAD(P)H to the cumulative NAD(P)H fluorescence signal. Moreover, we demonstrate that protein–NAD(P)H complexes characterised by different fluorescence lifetimes are not uniformly distributed all over the cell, as assumed until now, but are concentrated in certain cellular regions. The different fluorescence lifetimes indicate either different protein–NAD(P)H complexes or different bond strengths between NAD(P)H and the protein in these complexes.Since an important aspect in biological applications is to monitor the dynamics of the relevant processes (such as cellular metabolism), rapid dynamical techniques, for example, rapid biexponential fluorescence lifetime imaging, are needed. Furthermore, it is necessary to reduce the evaluation effort as much as possible. Most of the evaluation techniques in multiexponential FLIM are time‐expensive iterative methods. The few exceptions are connected with a loss of information, for example, global analysis; or a loss in accuracy, for example, the rapid evaluation technique (RLD). We implement for the first time in FLIM a noniterative, nonrestrictive method originally developed by Prony for approximations of multiexponential decays. The accuracy of this method is verified in biexponential FLIM experiments in time‐domain on mixtures of two chromophores both in homogenous and in heterogeneous media. The resulting fluorescence lifetimes agree (within error margins) with the lifetimes of the pure substances determined in monoexponential FLIM experiments. The rapidity of our evaluation method as compared to iterative pixel‐by‐pixel methods is evidenced by a reduction of the evaluation time by more than one order of magnitude. Furthermore, the applicability of this method for the biosciences is demonstrated in the investigation of cellular metabolism by means of NAD(P)H endogenous fluorescence.
Self‐Assembly and Characterization of Hydrogen‐Bond‐Induced Nanostructure Aggregation
Authors: Liu Yang , Zhuang Junpeng , Liu Huibiao , Li Yuliang , Lu Fushen , Gan Haiyang , Jiu Tonggang , Wang Ning , He Xiaorong , Zhu Daoben 
Published: August 2004

AbstractA supramolecular system of a perylene derivative containing bis(2,6‐diacylaminopyridine) units and a perylene bisimide bound through three hydrogen‐bonds was synthesized and characterized. 1H NMR spectra confirmed the existence of hydrogen‐bonding interactions between the perylene derivative (3) and the perylene bisimide (7). The photocurrent generation of the self‐assembled 3⋅7 film was measured, and a cathodic photocurrent response was obtained. SEM images indicated that well‐defined long fibers could be fabricated by self‐assembly, by exploiting the hydrogen bonding interactions and π‐π stacking interactions of perylene rings.
Conservation of structure and functional divergence of duplicated Wnt8s in pufferfish
Authors: Ramel Marie‐Christine , Buckles Gerri R. , Lekven Arne C. 
Published: August 2004

AbstractThe zebrafish wnt8 locus differs from its tetrapod counterparts in that it produces two functionally overlapping but distinct Wnt8 proteins. Studies of zebrafish wnt8 have suggested that the two major Wnt8 proteins produced are functionally similar yet may behave differently depending on the assay context. To determine whether the bicistronic wnt8 and its accompanying unique protein activities found in zebrafish are more widespread (and perhaps universal) among teleosts, we have extended our studies to the pufferfish Takifugu rubripes. We have found that Takifugu wnt8 is also bicistronic, indicating that the wnt8 duplication occurred before the divergence of these teleosts approximately 150 million years ago. Furthermore, overexpression assays in zebrafish embryos show that functional differences between the zebrafish Wnt8.1 and Wnt8.2 proteins are conserved in their Takifugu orthologs. Thus, despite the fact that Wnt8.1 and Wnt8.2 proteins are as similar to each other as each is to Xenopus Xwnt‐8, Wnt8 family members can behave quite differently in the context of zebrafish embryos. This finding suggests that zebrafish (and possibly teleost in general) Wnt8 receptors are able to discriminate between highly related ligands. Developmental Dynamics 231:441–448, 2004. © 2004 Wiley‐Liss, Inc.
Expression patterns of claudin family of tight junction membrane proteins in developing mouse submandibular gland
Authors: Hashizume Atsushi , Ueno Tomoo , Furuse Mikio , Tsukita Shoichiro , Nakanishi Yasuo , Hieda Yohki 
Published: August 2004

AbstractHere, we investigated the expression of the claudin family of tight junction transmembrane proteins in the developing mouse submandibular gland. Data obtained by reverse transcriptase‐polymerase chain reaction, Western blot, and immunofluorescence microscopy showed the expression and localization of claudin‐3 to ‐8, ‐10, and ‐11 at epithelial tight junctions. Examination of the glands taken from embryonic day (E) 14, E16, and newborn mice revealed differential expression patterns of these claudins in the developing epithelium. Claudin‐3, ‐5, and ‐7 were expressed in all of the luminal epithelial cells of the ducts at all of the developmental stages examined and in those of terminal tubules at E16 and later. Claudin‐4 was expressed mainly in the ducts at all the developmental stages. The expression of claudin‐6 and ‐8 was also restricted to the ducts at E14 and E16; but after birth, the former was undetectable, whereas the latter was expressed in both the ducts and terminal tubules. Claudin‐10 and ‐11 were detectable mainly in the terminal tubules at E16 and later. In addition to being found in the epithelium, claudin‐5 was also expressed in certain mesenchymal cells, probably endothelial cells. These results will provide a valuable resource for further investigation of tubulogenesis and physiological regulation of claudin‐based tight junctions. Developmental Dynamics 231:425–431, 2004. © 2004 Wiley‐Liss, Inc.
PP1β9C interacts with trithorax in Drosophila wing development
Authors: Rudenko Andrey , Bennett Daimark , Alphey Luke 
Published: August 2004

AbstractType 1 Ser/Thr protein phosphatase (PP1) has many roles in Drosophila: regulating diverse processes from chromatin condensation to transforming growth factor‐β signaling. The presence of four PP1 genes, PP1α87B, PP1β9C, PP1α96A, and PP1α13C, encoding very similar proteins complicates analysis of their particular functions. Here, we report that the minor PP1 isoform PP1β9C binds in vitro and in vivo and genetically interacts with Trithorax (TRX), the archetypal member of the Trx‐G family of epigenetic regulators in Drosophila. Direct binding was demonstrated by GST pull‐down experiments and PP1β9C/TRX interaction in vivo was confirmed by coimmune precipitation from Drosophila embryonic extracts. PP1β9C was found to be present at all TRX sites on the polytene chromosomes. Flies homo‐ and hemizygous for loss‐of‐function alleles of PP1β9C exhibited specific wing defects when combined with various trx mutants, which indicates that PP1β9C and TRX cooperate in Drosophila wing development. Developmental Dynamics 231:336–341, 2004. © 2004 Wiley‐Liss, Inc.
Differential proliferative response of NKT cell subpopulations to in vitro stimulation in presence of different cytokines
Authors: Lin Henry , Nieda Mie , Nicol Andrew J. 
Published: August 2004

AbstractHuman Vα24+Vβ11+ NKT (NKT) cells have immune regulatory activities associated with rejection of tumors, infections and control of autoimmune diseases. They can be stimulated to proliferate using α‐galactosylceramide (KRN7000) and have the potential for therapeutic manipulation. Subpopulations of NKT cells (CD4+CD8–, CD4–CD8+ and CD4–CD8–) have functionally distinctive Th1/Th2 cytokine profiles and their relative numbers following stimulation may influence the Th1/Th2 balance, which may result in or prevent disease. We aimed to determine the effect of different cytokines in culture during stimulation of NKT cells on the relative proportions of NKT cell subpopulations. Our results show that all NKT cell subpopulations expanded following stimulation with KRN7000 and IL‐2, IL‐7, IL‐12 or IL‐15. Expansion capacity differed between subpopulations, resulting in different relative proportions of CD4+ and CD4– NKT cell subpopulations, and this was influenced by the cytokine used for stimulation. A Th1‐biased environment was observed after stimulation of NKT cells. NKT cells expanded under all conditions evaluated demonstrated significant cytotoxicity against U937 tumor cells. In view of the potential for NKT cell subsets to alter the balance of Th1 and Th2 environment, these data provide insights into the effects of NKT cell manipulation for possible therapeutic applications in different disease settings.
Association of hepatitis C virus envelope proteins with exosomes
Authors: Masciopinto Francesca , Giovani Cinzia , Campagnoli Susanna , Galli‐Stampino Luisa , Colombatto Piero , Brunetto Maurizia , Yen T. S. Benedict , Houghton Michael , Pileri Piero , Abrignani Sergio 
Published: August 2004

AbstractAs the human tetraspanin CD81 binds hepatitis C virus (HCV) envelope glycoprotein E2, we addressed the role CD81 may play in cellular trafficking of HCV envelope proteins. Studies on HCV life cycle are complicated by the lack of a robust cell culture system; we therefore transfected mammalian cells with HCV E1‐E2 cDNA, with or without human CD81 (huCD81) cDNA. In the absence of huCD81, HCV envelope proteins are almost completely retained in the endoplasmic reticulum. Instead, when huCD81 is present, a fraction of HCV envelope proteins passes through the Golgi apparatus, matures acquiring complex sugars and is found extracellularly associated with exosomes. These are 60–100‐nm membrane vesicles enriched in tetraspanins, released into the extracellular milieu by many cell types and having fusogenic activity. We also report that human plasma contains exosomes and that in HCV patients, viral RNA is associated with these circulating vesicles. We propose that the HCV‐CD81 complex leaves cells in the form of exosomes, circulates in this form and exploits the fusogenic capabilities of these vesicles to infect cells even in the presence of neutralizing antibodies.
CCL3/MIP‐1α is pro‐inflammatory in murine T cell‐mediated hepatitis by recruiting CCR1‐expressing CD4+ T cells to the liver
Authors: Ajuebor Maureen N. , Hogaboam Cory M. , Le Tai , Proudfoot Amanda E. I. , Swain Mark G. 
Published: August 2004

AbstractT cell‐mediated hepatitis is associated with significant morbidity and mortality worldwide. Levels of C‐C chemokine ligand 3/macrophage inflammatory protein‐1α (CCL3/MIP‐1α) are elevated in the serum of patients with T cell‐mediated liver diseases, but its role is not fully understood. Con A‐induced hepatitis is a murine liver‐specific inflammation mediated by activated T cells and is driven by an up‐regulation of the hepatic expression of IFN‐γ. In this study, we have used CCL3/MIP‐1α gene‐deficient mice to examine the role of CCL3/MIP‐1α in the pathogenesis of Con A‐induced hepatitis. We demonstrate a novel pro‐inflammatory role for CCL3/MIP‐1α since CCL3/MIP‐1α deficiency significantly attenuated hepatic injury, both biochemically and histologically. Moreover, the recruitment of CCR1‐expressing CD4+ T cells to the liver after Con A treatment was strikingly attenuated by CCL3/MIP‐1α deficiency. Correspondingly, hepatic IFN‐γ produced by the recruited CD4+ T cells was significantly reduced by CCL3/MIP‐1α deficiency during Con A‐induced hepatitis. Furthermore, treatment of mice with a dual CCR1/CCR5 peptide antagonist, methionylated RANTES, also markedly reduced hepatic injury and decreased the numbers of CD4+ T cells within the liver producing IFN‐γ during Con A‐induced hepatitis. These findings demonstrate that blockade of the CCL3/MIP‐1α‐CCR1 pathway may represent a novel therapeutic target for treating T cell‐mediated liver diseases.
Anti‐apoptotic mechanism and reduced expression of phospholipase D in spontaneous and Fas‐stimulated apoptosis of human neutrophils
Authors: Lee Sun‐Young , Oh Ji‐Young , Lee Min‐Jung , Jang Min‐Jung , Park Hae‐Young , Kim Ja‐Woong , Min Do Sik , Park Yeong‐Min , Chang Young‐Chae , Bae Yoe‐Sik , Kwak Jong‐Young 
Published: August 2004

AbstractNeutrophil apoptosis is a constitutive process that can be enhanced or delayed by signals triggered by various stimuli. In this work, we investigated the action mechanism of phospholipase D (PLD) and its expression in the inhibition of spontaneous and Fas‐mediated apoptosis. Anti‐Fas antibody‐stimulated apoptosis of neutrophils was significantly blocked by the exogenous addition of bacterial PLD from Streptomyces chromofuscus (scPLD), and neutrophils cultured for 24 h in the presence of anti‐Fas antibody showed lower agonist‐stimulated PLD activity compared to untreated cells. The amount of PLD1a protein reduced time‐dependently in cultured neutrophils, but was recovered by treating with LPS or GM‐CSF. The reduction in PLD1a protein level was blocked by caspase inhibitors. The exogenous addition of scPLD blocked the up‐regulation of Fas‐associated death domain expression, mitochondrial permeability, and the cleavages of procaspase‐8, procaspase‐3, and protein kinase C‐δ. We also found that the protein level of apoptosis‐inducing factor was increased in cultured neutrophils but its expression was reduced by scPLD. However, sulfasalazine‐induced apoptosis and change of protein expression were not blocked by scPLD. Taken together, the activity and protein levels of PLD play a role as an anti‐apoptotic factor by acting at multiple levels of the apoptotic cascade in neutrophils.
Cross‐presentation of a human tumor antigen delivered to dendritic cells by HSV VP22‐mediated protein translocation
Authors: Chhabra Arvind , Mehrotra Shikhar , Chakraborty Nitya G. , Mukherji Bijay , Dorsky David I. 
Published: August 2004

AbstractDendritic cells (DC) capture antigens from apoptotic and/or necrotic tumor cells and cross‐present them to T cells, and various ways of delivering tumor antigens to DC in vitro and in vivo are being pursued. Since fusions of antigenic proteins with the HSV integument protein VP22 are capable of intercellular trafficking, this approach has been exploited for delivery of antigens to antigen‐presenting cells. Adenoviral vectors were used to express the tumor‐associated‐but‐self‐antigen MART‐1 fused to HSV VP22 in MART‐1‐negative A375 melanoma cells and in DC. When expressed in A375 cells and allowed to spread to DC across a transwell barrier, the VP22‐MART‐1 fusion protein localized to both early and late endosomal structures of the DC. The DC loaded with the VP22‐MART‐1 fusion by intercellular trafficking efficiently presented the MART‐127–35 epitope to MART‐127–35‐specific CTL. Furthermore, transloaded DC were capable of expanding the population of MART‐127–35‐specific CTL. Thus, a tumor antigen acquired by intercellular trafficking can be cross‐presented by DC. This experimental approach should therefore be useful not only for studying the mechanism of cross‐presentation but also for vaccine development.