bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous presentation and cross‐presentation of immune‐stimulating complex‐associated cognate antigen by antigen‐specific B cells
Authors: Robson Neil C. , Donachie Anne M. , Mowat Allan McI. 
Published: April 2008

AbstractWe demonstrate that uptake of oligomeric cognate antigen (OVA‐hen egg lysozyme, OVA‐HEL) alone or incorporated in immune‐stimulating complexes (ISCOMS) facilitates presentation and simultaneous cross‐presentation of OVA by HEL‐specific B cells in vitro. HEL‐specific B cells stimulated CD8+ T cell responses in vitro to the same extent as bone marrow‐derived dendritic cells. Cross‐presentation by specific B cells required endosomal acidification, proteasomal processing and classical MHC class I/peptide transport. Specific B cells also acquired both antigens rapidly in vivo and presented them to CD4+ T cells. However, only HEL‐specific B cells from OVA‐HEL ISCOMS‐immunised mice could cross‐present OVA to naive OVA‐specific CD8+ T cells. Antigen‐specific B cells were also activated selectively by OVA‐HEL ISCOMS in vitro and importantly, the presence of HEL‐specific B cells promoted the persistence of clonal expansion of OVA‐specific CD8+ T cells after in vivo immunisation with OVA‐HEL ISCOMS. These results demonstrate preferential MHC class I and class II processing of cognate antigen incorporated in ISCOMS by specific B cells in vitro and in vivo, highlighting the ability of ISCOMS to target B cells and offering novel insights into the role of B cells in cross‐presentation to CD8+ T cells.
Antigen structure influences helper T‐cell epitope dominance in the human immune response to HIV envelope glycoprotein gp120
Authors: Mirano‐Bascos Denise , Tary‐Lehmann Magdalena , Landry Samuel J. 
Published: April 2008

AbstractThe development of an effective vaccine against HIV/AIDS has been hampered, in part, by a poor understanding of the rules governing helper T‐cell epitope immunodominance. Studies in mice have shown that antigen structure modulates epitope immunodominance by affecting the processing and subsequent presentation of helper T‐cell epitopes. Previous epitope mapping studies showed that the immunodominant helper T‐cell epitopes in mice immunized with gp120 were found flanking flexible loops of the protein. In this report, we show that helper T‐cell epitopes against gp120 in humans infected with HIV are also found flanking flexible loops. Immunodominant epitopes were found to be located primarily in the outer domain, an average of 12 residues C‐terminal to flexible loops. In the less immunogenic inner domain, epitopes were found an average of five residues N‐terminal to conserved regions of the protein, once again placing the epitopes C‐terminal to flexible loops. These results show that antigen structure plays a significant role in the shaping of the helper T‐cell response against HIV gp120 in humans. This relationship between antigen structure and helper T‐cell epitope immunodominance may prove to be useful in the development of rationally designed vaccines against pathogens such as HIV.
Acetylenetitanium Complex Stabilized by Aminopyridinato Ligands
Authors: Noor Awal , Kempe Rhett 
Published: April 2008

AbstractThe first acetylenetitanium complex stabilized by aminopyridinato ligands has been prepared by the reaction of Ap2TiCl2 (1) – Ap‐H = 2‐[(2,6‐diisopropylphenyl)amino]pyridine – with equimolar amount of bis(trimethylsilyl)acetylene in the presence of magnesium. The complex was characterized by spectroscopic methods as well as by X‐ray single crystal structure analysis. Reduction of 1 with KC8 under N2 in the absence of any other stabilizing ligand leads to the ligand rearrangement product Ap3Ti. In the reaction of the acetylenetitanium complex with acetone the titanaoxacyclopentene was formed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Dual Supermesityl Stabilization: A Room‐Temperature‐Stable 1,2,4‐Triphosphole Radical, Sigmatropic Hydrogen Rearrangements, and Tetraphospholide Anion
Authors: Ionkin Alex S. , Marshall William J. , Fish Brian M. , Marchione Alexander A. , Howe Laurie A. , Davidson Fredric , McEwen Charles N. 
Published: April 2008

AbstractCesium 3,5‐bis(2,4,6‐tri‐tert‐butylphenyl)‐1,2,4‐triphospholide (12) and cesium 5‐(2,4,6‐tri‐tert‐butylphenyl)tetraphospholide (13) were synthesized and isolated with flat five‐membered rings, which are an indication of the aromaticity in these anions. Compound 13 is the first example of a stable tetraphospholide anion, which is structurally characterized. Kinetic stabilization of the 1,2,4‐triphospholide system by two supermesityl groups resulted in the detection of the room‐temperature‐stable radical 17 and the observation of a series of successive sigmatropic hydrogen shifts in the first stable 1H‐1,2,4‐triphosphole 14 with a P–H bond.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Enantiopure Highly Functionalized Pyrrolizines and Indolizines from Natural α‐Amino Acids: An Ex­perimental and Theoretical Investigation
Authors: Borsini Elena , Broggini Gianluigi , Contini Alessandro , Zecchi Gaetano 
Published: April 2008

AbstractVariously substituted enantiopure 2‐benzylamino‐1‐hydroxymethyl‐2,3‐dihydro‐1H‐pyrrolizines and 6‐benzylamino‐5,6,7,8‐tetrahydroindolizin‐8‐ols have been prepared. The reaction sequence starts from L‐α‐amino acids and involves an intramolecular cycloaddition of pyrrole‐based nitrone intermediates. A theoretical investigation at the HCTH/6‐311+G(d,p)//HCTH/6‐31+G(d) level of theory was performed with the aim of rationalizing the effects of substituents on the regiochemistry of the cycloaddition reaction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A First Case of Asymmetric Catalysis Induced by Metal‐Free Bisoxazolines
Authors: Akalay Deniz , Dürner Gerd , Göbel Michael W. 
Published: April 2008

AbstractMetal‐free bisoxazolines catalyze the Diels–Alder reaction of N‐substituted maleimides with anthrone derivatives leading to products in excellent yields and enantioselectivities up to 70 %. A mechanism relying on Brønsted‐base catalysis is assumed to be involved with formation of an ion pair between the protonated catalyst and the anthrone enolate, which acts as a diene.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reaction Pattern in Vertebrate Cells (RiV): May the anti‐RiV ELISA Detect a Pathologic Cell Proliferation? (First Results)
Authors: Liebermann H. E. H. 
Published: April 2008

AbstractRiV is mainly represented by characteristic exosome‐like particles with a diameter of 30 to 70 nm. RiV particle preparations (RiV‐PP) contain identified proteins. In the present paper, the authors started an evaluation of the hypothesis, that RiV‐reactive antibodies, detected in patient sera by an indirect ELISA, may be used for the diagnosis of pathologic cell proliferations. On the basis of the frequency distribution curve of about 500 blood donor sera, cut‐off values for RiV‐reactive IgG and IgM antibodies could be defined. Additionally it was found that 1.6 % of blood donor sera reacted strongly with an RiV‐PP (of calf kidney cells) for IgG antibodies. 29 % of cancer patient sera (n = 48), 17 % of 53 patients with endoprothetics and with lung disorders, 44.3 % of 115 patient sera of a doctor's practice and 28 % of 97 sera of 10 to 11 years old schoolchildren were positive in the anti‐RiV ELISA with IgG antibodies. About half of the selected group of schoolchildren contained different autoantibodies and some of these children displayed already insulin dependent diabetes mellitus (as shown by others). A correlation of our ELISA results with the other autoimmune antibody results was not found. Using RiV‐PP as an antigen complex, isolated from calf kidney cell cultures or from human FL cell cultures and HeLa cell cultures, results with small differences between human and animal RiV origin were obtained. Using the human RiV, the number of positive sera was not significantly lower. Generally, the anti‐RiV ELISA, using RiV‐PP from human cell cultures, detect autoantibodies against RiV‐specific proteins. This assay may detect, but not diagnose pathologic cell proliferation. The possibilities of RiV ELISA for diagnostics of defined autoimmune diseases, as well as further studies and the more meaningful RiV immunoblot are discussed.
The two‐user Gaussian interference channel: a deterministic view
Authors: Bresler Guy , Tse David 
Published: April 2008

AbstractThis paper explores the two‐user Gaussian interference channel through the lens of a natural deterministic channel model. The main result is that the deterministic channel uniformly approximates the Gaussian channel, the capacity regions differing by a universal constant. The problem of finding the capacity of the Gaussian channel to within a constant error is therefore reduced to that of finding the capacity of the far simpler deterministic channel. Thus, the paper provides an alternative derivation of the recent constant gap capacity characterisation of Etkin, Tse and Wang. Additionally, the deterministic model gives significant insight towards the Gaussian channel. Copyright © 2008 John Wiley & Sons, Ltd.
Olfactory properties of straight‐chain undecan‐x‐ones, undecan‐x‐ols (x = 2–6) and their derivatives
Authors: Gibka Julia , Gliński Marek 
Published: April 2008

AbstractA series of undecan‐x‐ones (x = 2–6) was used as starting material in the synthesis of ethylene and propylene acetals, undecanols and their acetates. Undec‐3‐yl and undec‐6‐yl acetates, ethylene acetal of undecan‐3‐one and propylene acetals of undecan‐x‐ones (x = 2–5) have not yet been described. The odour properties for all the synthesized compounds have been determined. They have pleasant, fruity, herbaceous odours that can be described as food odours. The most valuable groups of compounds are ketones and their acetals, which have intense, pleasant, fruity, vegetable, spicy or herbaceous odours. In the case of alcohols, mild odours dominate with fruity, wooden or floral notes. All acetates have faint or mild fatty‐soapy odours. A correlation between the structure of the studied compounds and their odours has been found. Fruity odours appear among ketones and alcohols when a shift of the functional group from position 2 to the middle of the molecule occurs. In the studied ethylene and propylene acetals this shift strengthens their vegetable and spicy odours, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Essential oil variability in Baccharis uncinella DC and Baccharis dracunculifolia DC growing wild in southern Brazil, Bolivia and Uruguay
Authors: Frizzo Caren D. , Atti‐Serafini Luciana , Laguna Sergio Echeverrigaray , Cassel Eduardo , Lorenzo Daniel , Dellacassa Eduardo 
Published: April 2008

AbstractEssential oils of Baccharis uncinella DC and B. dracunculifolia DC collected from different wild populations growing in Bolivia, southern Brazil and Uruguay were analysed using gas chromatography and gas chromatography–mass spectrometry techniques, to check for chemical variability. Cluster analysis led to the identification of two chemotypes for B. dracunculifolia, related to aromadendrane‐ or cadinane‐derived components. As the timing of sampling of the plant material may have an influence on the composition of the essential oil isolated, the seasonal influence at the moment of harvesting was studied for two populations of each species. The results suggested that the flowering season was optimal both species and this supported the practice of harvesting at the full bloom stage. Copyright © 2008 John Wiley & Sons, Ltd.
Chemical composition and antibacterial activity of the essential oil from Mentha suaveolens ssp. insularis (Req.) Greuter
Authors: Sutour Sylvain , Bradesi Pascale , de Rocca‐Serra Dominique , Casanova Joseph , Tomi Félix 
Published: April 2008

AbstractA detailed analysis of Mentha suaveolens ssp. insularis (Req.) Greuter essential oil (EO) and hydrolate extract (HE) was carried out by combination of GC–RI, GC–MS and 13C‐NMR spectroscopy. After fractionation by column chromatography, 51 components of the EO and 27 components of the HE, accounting for 96.1% and 98.3%, respectively, were identified. The main components were pulegone (44.4% and 14.8%) and cis‐cis‐p‐menthenolide (27.3% and 67.3%). This α‐methylen‐γ‐butyrolactone, reported for the first time as a natural product, was isolated and its structure elucidated by 1D and 2D NMR spectroscopy. Both EO and HE exhibited a fair antibacterial activity against Staphylococcus aureus and Bacillus cereus. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of tissue‐specific emission of volatiles by the flowers of six Camellia species
Authors: Jullien Frédéric , Gao Jiyin , Orel George , Legendre Laurent 
Published: April 2008

AbstractScent production is a rare phenomenon in the genus Camellia, which is otherwise very diverse. This study provides the first report of GC–MS analyses of the volatile compounds synthesized and emitted by six Camellia species belonging to three subgenera. Solvent extracts mainly contained derivatives of the terpenoid, phenylpropanoid and fatty acid metabolisms. Members of subgenus Metacamellia mainly accumulated 2‐phenylethanol, while C. japonica of subgenus Camellia mainly synthesized monoterpenes and C. yuhsienensis of subgenus Paracamellia displayed a balanced mix of constituents. Headspace analysis of emitted volatiles confirmed the volatile composition and the rosy note of the scent of all species (due to 2‐phenylethanol, (±) linalool and some of their derivatives). Analysis of dissected tissues revealed that stamens accumulated 3–50 times more volatiles than petals and that carpels and sepals were the weakest producers of volatiles. These latter organs were the main source of heptanol. Phenylpropanoid and terpenoid derivatives accumulated differentially in both petals and stamens. Tissue distribution differed among Camellia species. Copyright © 2008 John Wiley & Sons, Ltd.
Diterpene‐rich needle oil of Pinus pinaster Ait. from Corsica
Authors: Ottavioli Josephine , Bighelli Ange , Casanova Joseph 
Published: April 2008

AbstractThe composition of 46 samples of needle oil of maritime pine (Pinus pinaster Ait.) from Corsica was investigated by gas chromatography (GC) in combination with retention indices, GC–MS and 13C‐NMR. Sixty compounds, accounting for 82.9–97.0% of the oil, were identified. The oils consisted mainly of mono‐, sesqui‐ and diterpene hydrocarbons, especially α‐pinene (6.4–29.4%), (E)‐β‐caryophyllene (4.4–19.9%), germacrene D (1.7–21.4%) and abieta‐7,13‐diene (6.8–34.2%). Although the composition varied substantially from sample to sample, k‐means partitioning and principal component analysis (PCA) of the compositional data suggested the occurrence of only one group within the 46 individual samples. The composition dominated by diterpene hydrocarbons (up to 61%) is reported for the first time. Copyright © 2008 John Wiley & Sons, Ltd.
Composition of essential oil from seeds of Nigella sativa L. cultivated in Poland
Authors: Wajs Anna , Bonikowski Radoslaw , Kalemba Danuta 
Published: April 2008

AbstractForty‐eight compounds have been identified in the essential oil from Nigella sativa (black cumin) seeds, 14 of which are volatiles that have never been isolated from black cumin before. This is the first time to show two monoterpenoids: cis‐ and trans‐4‐methoxythujane, occur naturally in plants, specifically in the essential oil from N. sativa seeds in 0.3% and 4%, respectively. The structures of the 4‐methoxythujanes were established by both spectroscopic and chemical methods. Copyright © 2008 John Wiley & Sons, Ltd.
Variation in the chemical composition and yield of essential oil of rose‐scented geranium (Pelargonium sp.) by the foliar application of metallic salts
Authors: Prasad Arun , Chattopadhyay Amitabha , Yadav Anju , Kumari Raj 
Published: April 2008

AbstractThe effects of foliar application of metallic salts (0.5% aqueous solution of sodium chloride, calcium chloride, iron sulphate, zinc sulphate, copper sulphate and nickel sulphate) on the chemical composition and yield of essential oil of rose‐scented geranium (Pelargonium sp.) was studied in a pot experiment. The content of linalool, geraniol and 10‐epi‐γ‐eudesmol in the geranium oil significantly increased and that of geranial and β‐bourbonene decreased by the foliar application of metallic salts as compared to control plants. The increase in the content was 53.3%, 15.8%, 6.6%, 109.2%, 13.3% and 54.2% in linalool and 17.8%, 26.8%, 39.1%, 36.6%, 24.8% and 38.8% in geraniol over the control by the application of sodium chloride, calcium chloride, iron sulphate, zinc sulphate, copper sulphate and nickel sulphate, respectively. The content of 10‐epi‐γ‐eudesmol was increased by 24.2%, 16.3%, 36.9%, 24.2%, 17.1% and 23.7% over the control by the application of sodium chloride, calcium chloride, iron sulphate, zinc sulphate, copper sulphate and nickel sulphate, respectively. The level of cis‐ and trans‐rose oxide in geranium oil significantly increased and that of neral decreased by the application of sodium chlorides, zinc sulphate and nickel sulphate as compared to control. cis‐3‐Hexenol, isomenthone, neo‐isomenthol, citronellol and citronellyl formate 2‐phenylethyl tiglate and geranyl tiglate content in geranium oil was not significantly affected by the foliar application of metallic salts. The herbage and oil yield of geranium significantly increased by the foliar application of metallic salts as compared with control plants. The increase in yield was 9.9%, 9.4%, 30.6%, 29.7%, 28.6% and 21.6% in herbage and 41.9%, 23.4%, 29.6%, 29.6%, 41.9% and 41.9% in oil yield over control by the application of sodium chloride, calcium chloride, iron sulphate, zinc sulphate, copper sulphate and nickel sulphate, respectively. The oil content in the geranium was enhanced by the application of sodium chloride, calcium chloride, copper sulphate and nickel sulphate, whereas application of iron sulphate and zinc sulphate had no significant effect on the oil content. Copyright © 2008 John Wiley & Sons, Ltd.
In vitro study on the anticandidal activity of Melaleuca alternifolia (tea tree) essential oil combined with chitosan
Authors: Juliano Claudia , Demurtas Carla , Piu Luisella 
Published: April 2008

AbstractThe in vitro activities of commercial Melaleuca alternifolia essential oil (tea tree oil; TTO) and chitosan were investigated against Candida albicans, both alone and in combination, to assess their potential synergistic action; their anticandidal properties were assessed using standard microbiological techniques, such as MIC evaluation and a ‘time–kill’ test. Our results demonstrated that both TTO and chitosan possess remarkable activity against Candida: TTO inhibited C. albicans at 0.5 % v/v and was able to kill yeast cells in 120 min at 1% and in 300 min at 0.5–0.25%; as far as chitosan was concerned, 0.5 mg/ml were required to inhibit Candida growth in liquid medium, whereas 0.5–2 mg/ml chitosan required 24 h to kill them in the ‘time–kill’ test; this effect was pH‐dependent, being present at pH 5.0 and disappearing at pH 2.0. When TTO and chitosan were tested together, the polymer reduced the MIC of TTO but did not enhance the activity of the oil as evaluated in the ‘time–kill’ test. Copyright © 2008 John Wiley & Sons, Ltd.
Antioxidant activity and characterization of volatile extracts of Capsicum annuum L. and Allium spp.
Authors: Jang Hae‐Won , Ka Mi‐Hyun , Lee Kwang‐Geun 
Published: April 2008

AbstractPlants that are commonly used in kimchi, a traditional Korean fermented food, include Capsicum annuum L. (green pepper), Allium fistulosum L. (Welsh onion), Allium cepa L. (onion) and Allium scorodoprasm L. (garlic), each of which has its own aroma. Aroma extracts of the plants were isolated by steam distillation under reduced pressure (DRP) and liquid–liquid continuous extraction (LLE). The aroma extracts were identified by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The major aroma compounds of the plant extracts were sulphides, alcohols and heterocyclic compounds. Antioxidant activities of the aroma extracts were evaluated using two different assays. The aroma extracts isolated from green pepper, Welsh onion, onion and garlic inhibited the oxidation of hexanal by 51%, 95%, 96% and 98%, respectively, for 1 month at a level of 500 µg/ml; these extracts inhibited malonaldehyde formation from cod liver oil by 49%, 58%, 62% and 58%, respectively, at a level of 500 µg/ml. Their antioxidant activities were comparable to that of the natural antioxidant α‐tocopherol. Copyright © 2008 John Wiley & Sons, Ltd.
Thermal Conductivity and Contact Resistance of Compressed Gas Diffusion Layer of PEM Fuel Cell
Authors: Nitta I. , Himanen O. , Mikkola M. 
Published: April 2008

AbstractThis paper discusses the effect of compression pressure on the mechanical and thermal properties of gas diffusion layers (GDL). The stress–strain curve of the GDL revealed one nonlinear and two piecewise linear regions within the compression pressure range of 0–5.5 MPa. The thermal conductivity of the compressed GDL seems to be independent of the compression pressure and was determined to be 1.18 ± 0.11 W m–1 K–1 at room temperature. The thermal contact resistance between the GDL and graphite was evaluated by augmenting experiments with computer modelling. The thermal contact resistance decreased nonlinearly with increasing compression pressure. According to the results here, the thermal bulk resistance of the GDL is comparable to the thermal contact resistance between the GDL and graphite. A simple one‐dimensional model predicted a temperature drop of 1.7–4.4 °C across the GDL and catalyst layer depending on compression pressures.
Experimental Studies on the Influence of Operational Parameters on the Cold Start of a 2 kW Fuel Cell
Authors: Bégot S. , Harel F. , Kauffmann J. M. 
Published: April 2008

AbstractIn this paper, experimental investigations on the influence of operational parameters on PEM fuel cell cold start are presented. The effect of current density, stack impedance at 1 kHz prior to start, as well as gas flow rate, gas pressure, coolant flow rate and surrounding subfreezing temperature are studied. The experimental apparatus is briefly described. It includes a main unit at room temperature and a smaller separate unit in a climatic chamber. Low current density, high impedance prior to start, moderate subfreezing temperature (–5 °C), high gas flow rate, low gas pressure and low coolant flow rate are found to have a positive impact on the cold start performance. Combining these parameters, self start‐up of the fuel cell without additional energy is achieved at –5 °C in 30 min. The whole set of observations leads to the following hypotheses on freeze mechanism: in the first phase, dry membranes and low current lead to a transient phase of membrane humidification. Then, in the second phase, ice clogging of the active layers occurs. In the third phase, a variable quantity of the produced water reaches the gas diffusion layers and channels.
Inferring disability status from corrupt data
Authors: Kreider Brent , Pepper John 
Published: April 2008

AbstractIn light of widespread concerns about the reliability of self‐reported disability, we investigate what can be learned about the prevalence of work disability under various assumptions on the reporting error process. Developing a nonparametric bounding framework, we provide tight inferences under our strongest assumptions but then find that identification deteriorates rapidly as the assumptions are relaxed. For example, we find that inferences are highly sensitive to how one models potential inconsistencies between subjective self‐assessments of work limitation and more objective measures of functional limitation. These two indicators appear to measure markedly different aspects of health status. Copyright © 2008 John Wiley & Sons, Ltd.