bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein fractionation in a multicompartment device using Off‐Gel™ isoelectric focusing
Authors: Michel Philippe E. , Reymond Frédéric , Arnaud Isabelle L. , Josserand Jacques , Girault Hubert H. , Rossier Joel S. 
Published: March 2003

AbstractA new protein fractionation technique based on off‐gel isoelectric focusing (IEF) is presented, where the proteins are separated according to their isoelectric point (pI) in a multiwell device with the advantage to be directly recovered in solution for further analysis. The protein fractions obtained with this technique have then been characterized with polymer nanoelectrospray for mass spectrometry (MS) analyses or with Bioanalyzer for mass identification. This methodology shows the possibility of developing alternatives to the classical two‐dimensional (2‐D) gel electrophoresis. One species numerical simulation of the electric field distribution during off‐gel separation is also presented in order to demonstrate the principle of the purification. Experiments with pI protein markers have been carried out in order to highlight the kinetics and the efficiency of the technique. Moreover, the resolution of the fractionation was shown to be 0.1 pH unit for the separation of β‐lactoglobulin A and B. In addition, the isoelectric fractionation of an Escherichia coli extract was performed in standard solubilization buffer to demonstrate the performances of the technique, notably for proteomics applications.
A DNA sieving matrix with thermally tunable mesh size
Authors: Kan Cheuk Wai , Barron Annelise E. 
Published: March 2003

AbstractWe present a “proof‐of‐concept” study showing that a blend of thermo‐responsive and nonthermo‐responsive polymers can be used to create a DNA sieving matrix with a thermally tunable mesh size, or “dynamic porosity”. Various blends of two well‐studied sieving polymers for CE, including hydroxypropylcellulose (HPC), a thermo‐responsive polymer, and hydroxyethylcellulose (HEC), a nonthermo‐responsive polymer, were used to separate a double‐stranded DNA restriction digest (X174‐HaeIII). HPC exhibits a volume‐phase transition in aqueous solution which results in a collapse in polymer coil volume at ∼ 39°C. Utilizing a blend of HPC and HEC in a ratio of 1:5 by weight, we investigated the effects of changing mesh size on DNA separation, as controlled by temperature. High‐resolution DNA separations were obtained with the blended matrix at temperatures ranging from 25°C to 38°C. We evaluated changes in the selectivity of DNA separation with increasing temperature for certain pairs of small and large fragments. A pure HEC (nonthermo‐responsive) matrix was used over the same temperature range as a negative control. In the blended matrix, we observe a maximum in selectivity at ∼ 31°C for small DNA, while a significant increase in the selectivity of large‐DNA separation occurs at ∼ 36°C as the polymer mesh “opens”. We also demonstrate, through a temperature ramping experiment, that this matrix can be utilized to obtain high‐resolution separation of both small and large DNA fragments simultaneously in a single CE run. Blended polymer matrices with “dynamic porosity” have the potential to provide enhanced genomic analysis by capillary array or microchip electrophoresis in microfluidic devices with advanced temperature control.
Peptide separations and dissociation constants in nonaqueous capillary electrophoresis: Comparison of methanol and aqueous buffers
Authors: Psurek Arndt , Scriba Gerhard K. E. 
Published: March 2003

AbstractNonaqueous capillary electrophoresis was evaluated for its potential to separate peptides in methanolic background electrolytes in comparison to aqueous‐methanol (50% v/v) and water. Isomeric aspartyl dipeptides and Leu‐ and Met‐enkephalin served as model compounds. pKa values were determined in the three solvent systems based on the apparent pH scale and in the case of methanol additionally based on the conventional pH scale. Changing from water to methanol led to an increase of the ionization constants describing the dissociation equilibria of the carboxyl group and the amino group, respectively. The pKa shift was more pronounced for the carboxylic acid function leading to a compression of the mobility‐pH curve. As reported for aqueous buffers, efficient separations of the peptides were achieved in methanolic background electrolytes including the resolution of the diastereomers of the isomeric α‐ and β‐aspartyl dipeptides. In contrast to aqueous buffers, the separation of Leu‐ and Met‐enkephalin could also be obtained in buffers in methanol at high pH.
Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes
Authors: Koval Dušan , Kašička Václav , Jiráček Jiří , Collinsová Michaela 
Published: March 2003

AbstractPhosphinic pseudopeptides (i.e., peptide isosteres with one peptide bond replaced by a phosphinic acid moiety) were analyzed and physicochemically characterized by capillary zone electrophoresis in the pH range of 1.1–3.2, employing phosphoric, phosphinic, oxalic and dichloroacetic acids as background electrolyte (BGE) constituents. The acid dissociation constant (pKa) of phosphinate group in phosphinic pseudopeptides and ionic mobilities of these analytes were determined from the pH dependence of their effective electrophoretic mobilities corrected to standard temperature and constant ionic strength of the BGEs. It was shown that these corrections are necessary whenever precise mobility data at very low pH are to be determined. Additionally, it was found that the ionic mobilities of the phosphinic pseudopeptides and pKa of their phosphinate group are affected by the BGE constituent used. The variability of migration behavior of the pseudopeptides can be attributed to their ion‐pairing formation with the BGE components.
Electrophoretic mobility for peptides with post‐translational modifications in capillary electrophoresis
Authors: Kim Jeongkwon , Zand Robert , Lubman David M. 
Published: March 2003

AbstractSeveral semiempirical models for peptide electrophoretic mobility have been tested for capillary electrophoresis (CE) separation with a positively charged capillary using on‐line CE combined with electrospray ionization‐mass spectrometry (ESI‐MS). In the current system with pH 2.7, the expression q/M0.56 provided the best correlation with the electrophoretic mobility in the analysis of a set of 18 standard samples, where q is the calculated net charge and M is the molecular weight. The peptides resulting from various digests of horse heart myoglobin or bovine hemoglobin were used to demonstrate the validity of this correlation. Post‐translationally modified peptides from tryptic digest of human myelin basic protein were also investigated and were found to provide excellent correlation with the linear plot when the total charge of the peptide was correctly calculated. If the total charge was not properly calculated then the post‐translationally modified peptides fell off the linear plot. Using this method five arginine residues (residues 5, 49, 54, 97 and 130) were found to be partially citrullinated, four glutamine residues (residues 8, 103, 121 and 147) were found to be partially deamidated and both methionines at residues 21 and 167 were found to be partially oxidized. Three peptides were found with phosphorylation; TPPPSQGK (residue 98 to 105), FSWGAEGQR (residue 114 to 122), and SGSPMAR (residue 163 to 169) and Arginine at 107 was found to be partially monomethylated or dimethylated. The method may provide an excellent means of identifying the presence of peptides with post‐translational modifications in conjunction with MS.
Affinity capillary electrophoresis study of the linkage existing between proton and zinc ion binding to bacitracin A1
Authors: Castagnola Massimo , Rossetti Diana Valeria , Inzitari Rosanna , Vitali Alberto , Lupi Alessandro , Zuppi Cecilia , Cabras Tiziana , Fadda Maria Benedetta , Petruzzelli Raffaele , Giardina Bruno , Messana Irene 
Published: March 2003

AbstractMeasurements by capillary electrophoresis (CE) of bacitracin A1 effective mobility at different pH values permitted to estimate the five acidic dissociation constants and the Stokes radii at different protonation stages of the macrocyclic dodecapeptide. The pKa values were 3.6 and 4.4 for the two carboxylic groups of the lateral chains of D‐Asp‐11 and D‐Glu‐4, respectively, 6.4 for the aza‐atom of the imidazole ring of His‐10, 7.6 for the amino group of N‐terminal Ile‐1 and 9.7 for the δ‐amino group of D‐Orn‐7, very close to the values obtained by other researchers by titration experiments. In agreement with a rigid macrocyclic structure the Stokes radii of different protonated forms ranged only between 14.3 and 14.8 Å. Best fitting procedures performed on experimental mobility measured at two different pH values (5.50 and 6.72) in the presence of increasing Zn+2 concentration allowed confirming the model that assumes the binding of Zn+2 to P0 peptide form with a 1.5×103 M‐1 intrinsic association constant. Following to Zn+2 binding, the pKa of the amino group of N‐terminal Ile‐1 is shifted from 7.6 to 5.9 and the Stokes radius is reduced of about 3 Å. The mean charge of the bacitracin A1‐Zn+2 complex resulted +1.67 and +1.12 at pH 5.50 and 6.72, respectively. These results suggest that the amino group of N‐terminal Ile‐1 is not essential for Zn+2 binding.
Volatile constituents of Phlomis olivieri Benth. from Iran
Authors: Mirza M. , Nik Z. Baher 
Published: March 2003

AbstractThe essential oil, isolated by steam distillation from the aerial parts of Phlomis olivieri Benth. growing wild in Iran, was analysed by GC–MS. Among 15 identiﬁed compounds, the major components were germacrene D (28.1%), β‐caryophyllene (16.1%), α‐pinene (11.7%) and β‐selinene (10.2%). Copyright © 2003 John Wiley & Sons, Ltd.
Essential oils from the buds of Betula spp. growing in Turkey
Authors: Demirci Betül , Başer Kemal Hüsnü Can 
Published: March 2003

AbstractThe essential oils from buds of Betula browicziana A. Güner, B. litwinowii Doluch., B. medwediewii Regel, B. pendula Roth and B. recurvata V. Vassil. (Betulaceae) were either hydrodistilled using a Clevenger‐type apparatus or were subjected to Likens–Nickerson simultaneous distillation–extraction (SDE) when the plant material amounts were insufﬁcient. The resulting bud essential oils were analysed by GC–MS. Main components were detected as 14‐hydroxy‐β‐caryophyllene (1) and 14‐hydroxy‐4,5‐dihydro‐β‐caryophyllene (2) in all the oil samples. Copyright © 2003 John Wiley & Sons, Ltd.
Composition and niticidal activity of essential oils of three chemotypes of Rosmarinus ofﬁcinalis L. acclimatized in Morocco
Authors: Lahlou Mouhssen , Berrada Rached 
Published: March 2003

AbstractThe essential oils of three chemotypes of rosemary (Rosmarinus ofﬁcinalis L.) (Lamiaceae) were investigated in vitro for niticidal activity on Pediculus humanus capitis using two methods: microatmosphere and direct application. The results revealed the potent effectiveness of the oil of chemotype 1 (Rabat origin) using the two techniques mentioned, successively followed by the oils from chemotypes 2 (Errachidia origin) and 3 (Oujda origin). Chemical analysis (GC and GC–MS) of these oils was different. Among the main components identiﬁed, alcoholic and ketonic compounds were found the most effective on nits using the two methods. The difference in niticidal activity observed is related either to the technique used and to the chemical composition of the oils tested which is in direct relation to the geographical distribution of these chemotypes. Copyright © 2003 John Wiley & Sons, Ltd.
Volatile constituents of the leaves and flowers of Hypericum triquetrifolium Turra
Authors: Bertoli Alessandra , Menichini Francesco , Mazzetti Michele , Spinelli Guido , Morelli Ivano 
Published: March 2003

AbstractThe ﬂower and leaf oil of Hypericum triquetrifolium Turra (Guttiferae, Hypericoideae) from Calabria (Italy) were studied by GC and GC–MS. The major components identiﬁed in each oil were n‐nonane (8%, 15%), β‐pinene (8%, 4%), α‐pinene (13%, 10%), myrcene (16%, 5%), β‐caryophyllene (5%, 11%), germacrene‐D (10%, 13%), sabinene (13%, 3%) and caryophyllene oxide (5%, 12%) in the leaf and ﬂower oils, respectively. The aerial parts of the same plant were also analysed by SPME. The SPME analysis showed higher yields of undecane (14%, 10%) and β‐caryophyllene (14%, 10%) in comparison with the corresponding hydrodistillation oils, in addition to α‐pinene, β‐pinene, sabinene and myrcene, amounting to (9%, 6%), (7%, 4%), (1%, 9%), (1%, 10%) for the leaves and ﬂowers, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Composition of the essential oil of Perilla frutescens (L.) Britton from Turkey
Authors: Başer K. H. C. , Demirci B. , Dönmez A. A. 
Published: March 2003

AbstractWater‐distilled essential oil from the aerial parts of Perilla frutescens (L.) Britton, a recently recorded species in Turkey, was analysed by GC and GC–MS; 15 compounds were characterized, representing 88.1% of the oil, with perillaketone (35.6%) and isoegomaketone (35.1%) as the main constituents. Copyright © 2003 John Wiley & Sons, Ltd.
Use of gas chromatograms of the essential leaf oils of the genus Eucalyptus for taxonomic purposes: E. subser. Euglobulares (Blakely)
Authors: Dunlop Peter J. , Bignell Caroline M. , Hibbert D. Brynn , Brooker M. I. H. 
Published: March 2003

AbstractLeaves were harvested from 37 trees of Eucalyptus subser. Euglobulares Blakely, E. globulus Labill., E. bicostata Maiden, Blakely and Simmonds, E. maidenii F. Muell. and E. pseudoglobulus Naudin ex Maiden, selected from six sites around Australia: both native‐growing and cultivated taxa were chosen. Volatile leaf oils were isolated by vacuum distillation and analysed by GC (one tree was previously analysed by GC–MS). The conditions of distillation and analysis were maintained throughout this study. Many of the taxa contained α‐pinene (1.5–19.6%), limonene (1.0–5.1%), 1,8‐cineole (39.3–71.7%), p‐cymene (0.2–2.0%), pinocarvone (0.1–4.2%), β‐caryophyllene (0–5.5%), aromadendrene (0.9–20.3%), allo‐aromadendrene (0.1–4.0%), α‐terpineol (0.1–6.4%), globulol (0.1–5.5%), γ‐eudesmol (0–1.8%), α‐eudesmol (0.1–5.6%) and β‐eudesmol (0.1–10.8%) as the main leaf oil components. The principal components analysis (PCA) and linear discriminant analysis (LDA) performed on the gas chromatograms of the 37 single trees studied revealed groupings of the taxa in approximate agreement with the results obtained from comparative morphological studies; LDA yielded four distinct groups, while PCA was not as discriminating. Nevertheless, in both cases the ﬁve pseudoglobulus trees formed distinct groups of their own. In addition, the loading factors of the PCA analysis indicated that the pseudoglobulus group was due to the presence in this taxon of large amounts of the three eudesmol oil components. Copyright © 2003 John Wiley & Sons, Ltd.
The information content of implied volatility in agricultural commodity markets
Authors: Giot Pierre 
Published: March 2003

AbstractIn this article we compare the incremental information content of lagged implied volatility to GARCH models
of conditional volatility for a collection of agricultural commodities traded on the New York Board of Trade. We
also assess the relevance of the additional information provided by the implied volatility in a risk management
framework. It is first shown that past squared returns only marginally improve the information content provided
by the lagged implied volatility. Secondly, value‐at‐risk (VaR) models that rely
exclusively on lagged implied volatility perform as well as VaR models where the conditional variance is
modelled according to GARCH type processes. These results indicate that the implied volatility for options on
futures contracts in agricultural commodity markets provides relevant volatility information that can be used as
an input to VaR models. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:441–454, 2003
Bid‐ask spreads, volatility, quote revisions, and trades of thinly traded futures contracts
Authors: Ding David K. , Charoenwong Charlie 
Published: March 2003

AbstractWe investigate intraday bid‐ask spreads (BAS), volatility, and trading activity of thinly
traded equity index futures contracts on the Singapore Exchange. Contrary to previous findings, we find a rather
flat BAS pattern during the trading day. However, consistent with past findings, an increase in risk widens the
spread and a higher trading activity reduces it. When trading occurs in a day, spreads are reduced. No
significant difference in volatility between days with and without trades was detected. When trades occur, quote
revisions increase, and it is positively related to the number of trades. An increase in the number of quote
revisions increases the likelihood of a transaction, and when quotes are current, revisions that are accompanied
by trades carry new information. We provide evidence that contracts that are thinly traded may possess liquidity
attributes as long as their price quotes remain current. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark
23:455–486, 2003
Human homeobox gene HOXC13 is the partner of NUP98 in adult acute myeloid leukemia with t(11;12)(p15;q13)
Authors: La Starza Roberta , Trubia Maurizio , Crescenzi Barbara , Matteucci Caterina , Negrini Massimo , Martelli Massimo F. , Pelicci Pier Giuseppe , Mecucci Cristina 
Published: March 2003

AbstractThe chimeric gene NUP98/HOXC13 was detected in a patient with a de novo acute myeloid leukemia and a t(11;12)(p15;q13). Fluorescence in situ hybridization with PAC1173K1 identified the breakpoint on 11p15, indicating that the NUP98 gene was involved in the translocation. At 12q13, the breakpoint fell within BAC 578A18, selected for the homeobox C (HOXC) cluster genes. RACE‐PCR showed that HOXC13 was the partner gene of NUP98. To date, HOXC13 is the eighth homeobox gene that, as the result of a reciprocal translocation, fuses with NUP98 in myeloid malignancies. © 2003 Wiley‐Liss, Inc.
The interaction between cost‐management and learning for major surgical procedures – lessons from asymmetric information
Authors: Ernst Christian M. 
Published: March 2003

AbstractThe theory of the learning curve states that learning effects are of particular importance in industries, where human skills play an important role. Consequently, one would expect to find large learning effects for surgical procedures because the physician's experience is quite important for this type of work. For hospitals, there exists indeed a well‐documented effect that shows a positive relationship between the number of a certain type of surgery being performed and its resulting quality (volume–outcome relationship). Empirical analyses of the impact of learning on the average cost of a procedure, however, have noted a conspicuous absence of learning effects. Using a mechanism design approach, the paper analyzes a model of quality and cost‐management for a hospital, where learning effects are included into the cost function and asymmetric information exists between management and physician. It seeks to answer the question, whether recommendations from a symmetric information scenario with respect to learning carry over to a health care setting, where informational problems tend to be pronounced and severe. If surgery volume interacts with physicians' informational rents, an optimal management reaction to the presence of learning may result in a policy, which is the exact opposite of the one under symmetric information. Copyright © 2002 John Wiley & Sons, Ltd.
Lipoblastomatosis of the neck causing hemiparesis: A case report and review of the literature
Authors: Sun James J. , Rasgon Barry M. , Hilsinger Raymond L. 
Published: March 2003

AbstractBackground.Lipoblastoma and lipoblastomatosis are rare pediatric adipose tumors that sometimes affect the neck or spinal cord. This case is the third report of lipoblastoma extending into the spinal canal, the first report of intradural tumor extension, and the first report of hemiparesis resulting from lipoblastoma compressing the spinal cord.Methods.A 13‐month‐old boy was seen by a pediatrician for a firm, supraclavicular neck mass on the left side. After being evaluated by CT and MRI scanning, the tumor was partially resected.Results.Postoperative microscopic examination of the tumor showed adipose cells with mature nuclei and well‐formed fat vacuoles interspersed with fibrovascular septa, a finding consistent with maturing lipoblastoma.Conclusions.Although lipoblastomatous tumors are treated with complete surgical resection when possible, location of these tumors in the neck may dictate partial resection to avoid intraoperative injury to the spinal cord. © 2003 Wiley Periodicals, Inc. Head Neck 25: 337–340, 2003
Predictive value of the fraction of cancer cells immunolabeled for proliferating cell nuclear antigen or Ki67 in biopsies of head and neck carcinomas to identify lymph node metastasis: Comparison with clinical and radiologic examinations
Authors: Liu Ming , Lawson Georges , Delos Monique , Jamart Jacques , Ide Christophe , Coche Emmanuel , Weynand Birgit , Desuter Gauthier , Hamoir Marc , Remacle Marc , Marbaix Etienne 
Published: March 2003

AbstractBackground.Neck metastasis is a major prognostic factor of head and neck carcinoma, but its preoperative detection is currently unreliable. Molecular markers of the metastatic potential of a carcinoma would help to avoid unnecessary neck dissection in patients with nonmetastatic cancer.Methods.The fractions of cancer cells immunostained for proliferating cell nuclear antigen (PCNA) and Ki67 were determined in 80 preoperative biopsy specimens of head and neck carcinomas. The value of both indexes to detect metastasis in the subsequent neck dissection was compared with that of the clinical and radiologic examinations.Results.PCNA and Ki67 indexes correlated with neck metastasis. Cutoff points were determined for both indexes to discriminate metastatic from nonmetastatic carcinomas. By multivariate logistic regression, these indexes were significant predictors of metastases, together with clinical T stage and neck palpation.Conclusion.The fraction of cancer cells immunolabeled for PCNA or Ki67 in preoperative biopsy specimens is helpful to predict neck metastasis. © 2003 Wiley Periodicals, Inc. Head Neck 25: 280–288, 2003
Chemoselectivity and Conformational Analysis of the Reaction of 2‐Acetylcycloalkanones with Benzohydrazide: Synthesis and Reduction of 1‐Aroylcycloalkapyrazole Derivatives
Authors: Tsoleridis Constantinos A. , Stephanidou‐Stephanatou Julia , Zika Chara , Pozarentzi Minothora , Alevizopoulos Stephanos 
Published: March 2003

AbstractFrom the reaction of 2‐acetylcyclopentanone and 2‐acetyl‐2‐methylcyclopentanone with benzohydrazide, the 1‐benzoyl‐6a‐hydroxycyclopentapyrazole derivatives 2a and 2b were obtained as the only reaction products, whereas from the reaction of 2‐acetylcyclohexanone an epimeric cis/trans mixture of the 2‐benzoyl‐3‐hydroxy‐2H‐indazole derivative 3c was formed. The dehydration of the isolated compounds 2a and 3c, as well as the NaBH4 and NaBH3CN reduction products of 2a were studied. The structural assignments of the compounds derived were established by analysis of their NMR spectra (1H, 13C, DEPT, COSY, NOESY, HETCOR CH, and COLOC CH). The chemoselectivity of the reactions of 1a and 1c with benzohydrazide was studied by conformational analysis with MM2 and semiempirical (AM1 and PM3) MO calculations.