bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bet v 1, the major birch pollen allergen, initiates sensitization to Api g 1, the major allergen in celery: evidence at the T cell level
Authors: Bohle Barbara , Radakovics Astrid , Jahn‐Schmid Beatrice , Hoffmann‐Sommergruber Karin , Fischer Gottfried F. , Ebner Christof 
Published: November 2003

AbstractDue to IgE cross‐reactivity, birch pollen‐allergic individuals frequently develop type I hypersensitivity reactions to celery tuber. We evaluated the T cell response to the major allergen in celeriac, Api g 1, and the cellular cross‐reactivity with its homologous major allergen in birch pollen, Bet v 1. Api g 1‐specific T cell lines (TCL) and clones (TCC) were established from peripheralblood mononuclear cells of allergic patients. Epitope mapping of Api g 1 with overlapping Api g 1‐derived peptides revealed one dominant T cell‐activating region, Api g 1109–126. TCL and TCC generated with Api g 1 cross‐reacted with the birch pollen allergen and, although initially stimulated with the food allergen, cellular responses to Bet v 1 were stronger than to Api g 1. Epitopemapping with Bet v 1‐derived peptides revealed that T cells specific for several distinct epitopes distributed over the complete Bet v 1 molecule could be activated by Api g 1. Bet v 1109–126 was identified as the most important T cell epitope for cross‐reactivity with Api g 1. This epitope shares 72% amino acid sequence similarity with the major T cell‐activating region of the food allergen, Api g 1109–126. Our data provide evidence that humoral as well as cellular reactivity to the major celery allergen is predominantly based on cross‐reactivity with the major birch pollen allergen. The activation of Bet v 1‐specific Th2 cells by Api g 1, in particular outside the pollen season, may have consequences for birch pollen‐allergic individuals.
A phenotypically distinct subset of immature B cells exhibits partial activation, increased survival, and preferential expression of VhS107
Authors: Wilson Emily L. , Sherwood Erin M. , King Anne M. , Riley Richard L. 
Published: November 2003

AbstractWe have observed that immature B cells (IgMlowIgD–) in the bone marrow of adult BALB/c mice exhibit heterogeneity, with a distinct subpopulation (∼4–10%) expressing the CD43/S7 surface protein. These CD43/S7+ immature B cells often express other surface antigens associated with B cell activation (CD5, CD11b, PD‐1). Generation of optimal numbers of CD43/S7+ immature B cells requires expression of a functional Btk protein, consistent with activation as a requisite for the CD43/S7+ immature B cell phenotype. Like typical CD43/S7– immature B cells, the CD43/S7+ immature B cells are predominantly resting cells, which are derived from cycling bone marrow B cell precursors. The CD43/S7+ immature B cell population exhibits enhanced survival in vivo upon administration of the apoptosis‐inducing corticosteroid, dexamethasone. Finally, CD43/S7+ immature B cells show a fourfold increase in incidence of VhS107 μ heavy chain expression compared to the CD43/S7– immature B cells. Therefore, in adult murine bone marrow, the presence of a phenotypically distinct immature B cellpopulation can be demonstrated which has undergone partial activation leading to increased survival and BCR‐dependent Vh repertoire selection.
Thymic selection does not limit the individual MHC diversity
Authors: Borghans José A. M. , Noest André J. , De Boer Rob J. 
Published: November 2003

AbstractThe number of different major histocompatibility (MHC) molecules expressed per individual is widely believed to represent a trade‐off between maximizing the detection of foreign antigens, and minimizing the loss of T cell clones due to self‐tolerance induction. Using a mathematical model we here show that this argument fails to explain why individuals typically express of the order of 1020 different MHC molecules. Expression of extra MHC types decreases the number of clones surviving negative selection, but increases the number of positively selected clones. Based on experimental parameter estimates, we show that the number of clones in the functional T cell repertoire would in fact increase if the MHC diversity within an individual were to exceed its normal value, until more than one hundred different MHC molecules would be expressed. Since additional MHC types also increase the number of presented pathogen peptides, resistance against pathogens only decreases at unrealistically high MHC diversities exceeding 1,500 different MHC molecules per individual.
Breaking tolerance in hepatitis B surface antigen (HBsAg) transgenic mice by vaccination with cross‐reactive, natural HBsAg variants
Authors: Schirmbeck Reinhold , Dikopoulos Nektarios , Kwissa Marcin , Leithäuser Frank , Lamberth Kasper , Buus Soren , Melber Karl , Reimann Jörg 
Published: November 2003

AbstractProcessing exogenous hepatitis B surface antigen (HBsAg) of the hepatitis B virus (HBV) generates the Kb‐binding S208–215 epitope 1; processing endogenous HBsAg generates theKb‐binding S190–197 epitope 2. Cross‐reactive CD8+ T cell responses were primed to epitope 1 but not epitope 2 when mice were immunized with natural HBsAgayw, orHBsAgadw2 variants differing within both epitopes by one or two residues. Expression of HBsAgayw from a transgene in the liver renders (HBs‐tg) mice tolerant to epitope 1 of HBsAgayw. CD8+ T cells specific for epitope 1 could be primed in HBs‐tg mice by HBsAgadw2; these specific CD8+ T cells cross‐reacted with epitope 1 processed from the transgene‐encoded HBsAgayw. The liver of vaccinated HBsAgayw transgenic mice showed severe histopathology and contained functional (IFNγ‐producing), cross‐reactive CD8+ T cells, and vaccinated HBs‐tg mice showed reduced antigenemia. Hence, vaccination with natural HBsAg variants from different HBV sero/genotypes can prime cross‐reactive, specific CD8+ T cellimmunity that breaks tolerance to HBsAg.
Studies in the Cycloproparene Series: Unexpected Products from Peterson Olefinations
Authors: Halton Brian , Boese Roland , Dixon Gareth M. 
Published: November 2003

AbstractReaction of tetraphenylcyclopentadienone with anion 8 derived by monodesilylation of 1,1‐bis(trimethylsilyl)cyclopropa[b]naphthalene (10) gives the 1‐(5′‐cyclopentadienyl)‐substituted cycloproparene 17 from simple anion addition to the carbonyl group rather than fulvalene 16 from loss of Me3SiO−. Reactions of anion 8 with p‐(trifluoromethyl)benzaldehyde and thiophene‐2‐carbaldehyde give the expected exocyclic olefins 12a and 12b, respectively. In contrast, the 3,6‐dimethoxy analogue 24, obtained from cycloproparene 20, gives the C1 unsubstituted cycloproparene 19 and the Tishchenko products, p‐(trifluoromethyl)benzyl p‐(trifluoromethyl)benzoate (21) and 2‐thienylmethyl thiophene‐2‐carboxylate (22), respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A New Route for the Total Synthesis of 6,7‐Dihydroeponemycin
Authors: Bennacer Bibia , Rivalle Christian , Grierson David S. 
Published: November 2003

AbstractA new synthesis of dihydroeponemycin (2), a peptide epoxide with potent cytotoxic and antiangiogenesis activity, has been developed. In the initial steps, Fmoc‐Leu‐Cl was converted into the key amino ketone intermediate 9 by Stille coupling with tributylvinyltin, conjugate addition of PhSAlMe2 to the derived enone, S‐oxidation, and heat‐induced syn elimination. Subsequent reaction of 9 with H2O2 and catalytic Triton B produced the corresponding epoxides as a 1:1 diastereomeric mixture in 89 % yield. These epoxides were separated and individually converted into 2 and(2S)‐epi‐dihydroeponemycin (24) in a four‐step “one‐pot” protocol (77 % overall yield in both cases). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Preparation and Characterization of [5‐13C]‐(2S,4R)‐Leucine and [4‐13C]‐(2S,3S)‐Valine − Establishing Synthetic Schemes to Prepare Any Site‐Directed Isotopomer of L‐Leucine, L‐Isoleucine and L‐Valine
Authors: Siebum Arjan H. G. , Woo Wei Sein , Lugtenburg Johan 
Published: November 2003

AbstractIn this paper a chemo‐enzymatic method has been developed that gives access to any isotopomer of the essential amino acids isoleucine and valine. The method gives the correct introduction of the second chiral center in (2S,3S)‐isoleucine and allows for discrimination between the two prochiral methyl groups in valine as shown by the preparation of (2S,3S)‐[4‐13C] valine. For the preparation of (2S)‐leucine in any isotopomeric form, the O’Donnell method to prepare optically active amino acids has been used. The protected glycine scaffold used in this method has been prepared by a strategy that allows access to any isotopomeric form. The preparation of [5‐13C]‐(2S,4R)‐leucine shows that the O’Donnell method in combination with the Evans method to obtain chiral 2‐methylpropyl iodide leads to a good discrimination between the two prochiral methyl groups. The O’Donnell strategy for the preparation of α‐amino acids is preferred over other methods since the reaction conditions are mild, the chiral auxiliary can be easily recovered and the optically active product can be easily separated. For the preparation of isotopically enriched valine and isoleucine the O’Donnell method is not suitable, because the alkyl substituents involved have a secondary halide substituent which is sterically too hindered to give an effective reaction with the protected glycine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cyclisation of Novel Amino Oxo Esters to Tetramic Acids − Density Functional Theory Study of the Reaction Mechanism
Authors: Detsi Anastasia , Afantitis Antreas , Athanasellis Giorgos , Markopoulos John , Igglessi‐Markopoulou Olga , Skylaris Chris‐Kriton 
Published: November 2003

AbstractThe synthesis of novel N‐urethane‐protected γ‐methylamino‐β‐oxo esters and their use as precursors for the preparation of N‐methyltetramic acids is described. The presence of the bulky urethane protecting group on the nitrogen atom gives rise to rotational isomers detectable in the NMR spectra of the compounds, along with the keto/enol tautomerism. The mechanism of the cyclisation reaction of γ‐amino‐β‐oxo esters to tetramic acids was studied theoretically by the B3LYP hybrid density functional method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Zn(ClO4)2·6H2O as a Powerful Catalyst for a Practical Acylation of Alcohols with Acid Anhydrides
Authors: Bartoli Giuseppe , Bosco Marcella , Dalpozzo Renato , Marcantoni Enrico , Massaccesi Massimo , Sambri Letizia 
Published: November 2003

AbstractA new protocol for the acylation of alcohols with anhydrides in the presence of Zn(ClO4)2·6H2O as the catalyst is reported. The activity of Zn(ClO4)2·6H2O has been proven to be superior to that exerted by dry Mg(ClO4)2 and by metal triflates. Its efficiency allows reactions between poorly reactive substrates, such as sterically hindered tertiary alcohols and aromatic anhydrides. All of the reactions were carried out at a 1:1.05 alcohol/anhydride ratio. These conditions are extremely convenient from a practical and economic point of view, since they avoid wasting reagents and allow a simple workup procedure. The catalytic action of Zn(ClO4)2·6H2O is so specific for the activation of the anhydrides, that acid‐sensitive functionalities and the stereochemical configuration of the starting materials remain unaltered in the esterification process. In all cases, the acylated products are quantitatively obtained in pure form. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of New Hydroxy‐2‐styrylchromones
Authors: Santos Clementina M. M. , Silva Artur M. S. , Cavaleiro José A. S. 
Published: November 2003

AbstractHydroxy‐2‐styrylchromones 5a−i were prepared by debenzylation of benzyloxy‐2‐styrylchromones 3a−i, which were synthesised by the Baker−Venkataraman method. The last step of this method, the cyclodehydration 5‐aryl‐3‐hydroxy‐1‐(2‐hydroxyaryl)‐2,4‐pentadien‐1‐ones 2a−i, was carried out with a catalytic amount of iodine, or p‐toluenesulfonic acid, in DMSO. Benzyloxy‐3‐cinnamoyl‐2‐styrylchromones 4a−f were obtained as by‐products in both procedures, but the latter procedure gave benzyloxy‐2‐styrylchromones 3a−i in better yields. The structures of all new compounds were established by extensive NMR studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Evaluation Method of Smoothing Algorithms in Voltammetry
Authors: Jakubowska Malgorzata , Piech Robert , Dzierwa Tomasz , Wcislo Jacek , Kubiak Wladyslaw W. 
Published: November 2003

AbstractThe criterion for testing the influence of smoothing algorithms for the relevant parameters considered in analytical experiment is presented. The proposed approach assumes that the improvement of the whole set of measured curves should be considered. The calibration curve parameters with confidence intervals, correlation coefficient, detection limit, signal to noise ratio and parameters of recovery function are utilized for the evaluation. Performance of evaluation method is presented for several kinds of experimental noises.
The essential oils of Boesenbergia stenophylla R. M. Sm. as natural sources of methyl (E)‐cinnamate
Authors: Ahmad Fasihuddin bin , Jantan Ibrahim bin 
Published: November 2003

AbstractThe rhizome and leaf oils of Boesenbergia stenophylla R. M. Sm. were analysed by gas chromatography on two columns of different polarity, retention indices and GC–MS. The oils were found to possess compositional similarities but quantitative differences in the concentration of each component. The oils are natural sources of methyl (E)‐cinnamate, constituting 49.9–53.4% of the oils. They are also rich in sesquiterpenoids (39.8 and 40.3%, respectively) with δ‐elemene, β‐elemene, α‐santalene, α‐humulene, γ‐muurolene, spathulenol, caryophyllene alcohol and kaur‐16‐ene as the main representatives. Copyright © 2003 John Wiley & Sons, Ltd.
Composition of commercial Cape chamomile oil (Eriocephalus punctulatus)
Authors: Mierendorff Hanco‐Gisbert , Stahl‐Biskup Elisabeth , Posthumus Maarten A. , Beek Teris A. van 
Published: November 2003

AbstractCape chamomile oil obtained from the herb Eriocephalus punctulatus DC (Asteraceae) was analysed by GC and GC–MS. It was shown to consist of about 50 aliphatic esters, together amounting to more than 50% of the oil. 2‐Methylbutyl 2‐methylpropanoate (21.2%), 2‐methylbutyl 2‐methylbutanoate (5.6%), 2‐methylpropyl 2‐methylpropanoate (5.3%), and 7‐methyl‐2‐octyl acetate (4.5%) were the main components. In the terpenoid portion (about 37%), linalyl acetate (4.4%) and α‐pinene (1.9%) were the major compounds. In the higher boiling fraction, the artedouglasia oxides A–D, several davanones and laciniata furanones, oxygenated sesquiterpenes previously found in Artemisia species, could be detected in amounts of 5.9%, 0.4% and 1.4%, respectively. Commercial samples of different years showed almost identical compositions. Copyright © 2003 John Wiley & Sons, Ltd.
Application of co‐distillation with superheated pentane vapour to the isolation of unstable essential oils
Authors: Mastelić J. , Jerković I. 
Published: November 2003

AbstractHydrodistillation is the main method for essential oil isolation from aromatic plants. For unstable essential oils, this method is not suitable. For these cases, we have developed a method of isolation by co‐distillation with superheated pentane vapour. The method was studied using plant materials of Mentha citrata and Salvia sclarea, which contain unstable linalyl acetate as the main component of their essential oils. The essential oils of the same plants were also isolated by hydrodistillation as a standard method. The isolated volatiles (with both methods) were analysed by gas chromatography–mass spectrometry (GC–MS) and the obtained results were compared. Signiﬁcant differences were found in the qualitative and quantitative composition of isolated volatiles. The major components of the volatiles obtained by hydrodistillation and by co‐distillation with superheated pentane vapour, respectively, were linalyl acetate (26.5%, 55.5%), linalool (29.3%, 15.8%), 1,8‐cineole (7.2%, 3.5%), hedycaryol (6.2%, 6.6%) α‐terpineol (5.5%, 0.7%) and geranyl acetate (4.9%, 2.9%) for Mentha citrata; and linalyl acetate (21.2%, 33.4%), linalool (16.6%, 6.0%), myrcene (8.4%, 10.2%), geranyl acetate (7.3%, 6.7%) α‐terpineol (7.6%, 0.0%), trans‐β‐ocimene (4.4%, 6.4%) and geraniol (3.8%, 0%) for Salvia sclarea. The method of co‐distillation enables safe isolation of monoterpenes, but also sesquiterpene compounds as well as hydrodistillation. It is clear that this new method, unlike hydrodistillation, safely and remarkably diminishes artefact generation. Copyright © 2003 John Wiley & Sons, Ltd.
Composition of the essential oils of four medicinal plants from Ecuador
Authors: Malagón Omar , Vila Roser , Iglesias José , Zaragoza Tomás , Cañigueral Salvador 
Published: November 2003

AbstractThe composition of the essential oils from leaves of Lepechinia mutica, Satureja glabrata, Minthostachys mollis and Myrcianthes rhopaloides, four species used in traditional medicine in Loja (Ecuador), was investigated by GC–FID and GC–MS. Monoterpene hydrocarbons were the main group of constituents in the essential oil of L. mutica, especially β‐phellandrene (30%), whereas oxygenated monoterpenes predominated in the oils of M. mollis and M. rhopaloides, menthone (16%) and geranial (34%), respectively, being the major components. Although the oxygenated monoterpenes dominated the essential oil from S. glabrata (44%), the main constituent of this oil was isocaryophyllene (15%), followed by citronellol (14%) and citronellyl acetate (12%). Copyright © 2003 John Wiley & Sons, Ltd.
Cleft palate, transforming growth factor alpha gene variants, and maternal exposures: Assessing gene‐environment interactions in case‐parent triads
Authors: Jugessur Astanand , Lie Rolv T. , Wilcox Allen J. , Murray Jeffrey C. , Taylor Jack A. , Saugstad Ola D. , Vindenes Hallvard A. , Åbyholm Frank E. 
Published: November 2003

AbstractWe have previously reported a threefold risk of cleft palate only (CPO) among children homozygous for the less common allele A2 at the TaqI marker site of the transforming growth factor alpha gene (TGFA) (Jugessur et al. [2003a] Genet. Epidemiol. 24:230–239). Here we assess possible interaction between the child'sTGFATaqI A2A2 genotype and maternal cigarette smoking, alcohol consumption, use of multivitamins and folic acid. This was done by comparing the strength of genetic associations between strata of exposed and unexposed case‐parent triads. We also looked for possible gene‐gene interaction with the polymorphic variant C677T of the folic acid‐metabolizing geneMTHFR. We analyzed a total of 88 complete CPO triads selected from a population‐based study of orofacial clefts in Norway (May 1996–1998). No evidence of interaction was observed with either smoking or alcohol use. The risk associated with two copies of the A2 allele atTGFATaqI was strong among children whose mothers did not use folic acid (relative risk=4.5, 95% confidence interval=1.3–15.7), and was only marginal among children whose mothers reported using folic acid (RR=1.4, 95% CI=0.2–12.7). Although the interaction between the child's genotypes atTGFATaqI andMTHFR‐C677T was not statistically significant, the effect of theTGFATaqI A2A2 genotype appeared to be stronger among children with either one or two copies of the T‐allele at C677T (RR=4.0, 95% CI=1.1–13.9) compared to children homozygous for the C‐allele (RR=1.7, 95% CI=0.2–15.7). In conclusion, we find little evidence of interaction between the child's genotypes atTGFATaqI and various exposures for cleft palate, with the possible exception of folic acid intake.Genet Epidemiol25:367–374, 2003. © 2003 Wiley‐Liss, Inc.
Estimating the relative recurrence risk ratio using a global cross‐ratio model
Authors: Wallace Chris , Clayton David 
Published: November 2003

AbstractThe relative recurrence risk ratio λR (and particularly the sibling recurrence risk ratio, λS ) is often of interest to those wanting to quantify the genetic contribution towards risk of disease or to discriminate between different genetic models. However, estimating λR for complex diseases for which genetic and environmental risk factors are both involved is not straightforward. Ignoring environmental factors may lead to inflated estimates of λR. We present a marginal model which uses a copula function to model the association in cumulative incidence rates between pairs of relatives. This model is applicable to present‐state data and allows estimation of risk of disease in a pair of relatives (and hence λR), given measured environmental covariates. We apply the model to leprosy among sibling pairs from the Karonga district, Malawi. If risk factors are ignored, the apparent λS in this population is over 3. Accounting for known nongenetic risk factors reduces it to just under 2. Genet Epidemiol 25:293–302, 2003. © 2003 Wiley‐Liss, Inc.
Effects of process parameters on heterologous protein production in Aspergillus niger fermentation
Authors: Wang Liping , Ridgway Darin , Gu Tingyue , Moo‐Young Murray 
Published: November 2003

AbstractFilamentous fungi such as Aspergillus niger are attractive hosts for recombinant DNA technology because of their ability to secrete bioactive proteins with post‐translational processing such as glycosylation. Foreign genes can be incorporated into the chromosomes of the filamentous fungi, providing superior long‐term genetic stability. However, heterologous protein production is often severely hampered by fungal proteases. In this work, a recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP]#11 which carries a glucoamylase (GLA)‐green fluorescent protein (GFP) fusion gene was selected as a model system to study the effects of bioprocess parameters—agitation intensity, initial glucose concentration, initial yeast extract concentration, and dissolved oxygen tension (DO)—on extracellular protease inhibition and heterologous protein production. Based on previous experimental experience and results, a 24–1 fractional factorial design was applied to the experiments. Each parameter was tested at two levels. It was found that agitation affected the GFP production most significantly. Higher agitation rate resulted in higher GFP production. Protease activity was most influenced by initial glucose concentration and DO. Fungal morphology was also affected by these parameters. The effects of these parameters on pellet size and pellet porosity are discussed. Copyright © 2003 Society of Chemical Industry