bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the antidiabetic action of Mangifera indica in mice
Authors: Aderibigbe A. O. , Emudianughe T. S. , Lawal B. A. S.
Published: August 2002

The leaves of Mangifera indica were assessed for antidiabetic properties using normoglycaemic, glucose‐induced hyperglycaemia and streptozotocin (STZ) induced diabetic mice. The aqueous extract produced a reduction of blood glucose level in normoglycaemic and glucose‐induced hyperglycaemia, but did not have any effect on streptozotocin‐induced diabetic mice. The hypoglycaemic effect of the aqueous extract was compared with that of an oral dose of chlorpropamide under the same conditions. The results of this study indicate that the aqueous extract of the leaves of Mangifera indica possess hypoglycaemic activity. Copyright © 2001 John Wiley & Sons, Ltd.
Antiradical and antilipoperoxidative effects of some plant extracts used by Sri Lankan traditional medical practitioners for cardioprotection
Authors: J. Munasinghe T. Chaminda , Seneviratne Charita K. , Thabrew M. Ira , Abeysekera Ajith M.
Published: August 2002

Reactive oxygen species (ROS) are implicated in many pathogenic processes including the cardiovascular system. Detoxification of ROS by antioxidants (AO) therefore affords protection against such diseases. There is a growing body of evidence suggesting that antioxidants contribute to cardioprotection. Therefore, nine plants that are components of Ayurvedic formulations used for the therapy of cardiovascular diseases were investigated to determine whether antioxidant activity is one of the mechanisms by which these plants exert cardioprotection.

Initially aqueous freeze dried extracts of the plants were prepared and the antioxidant activity was measured (a) in vitro, by DPPH (1,1‐diphenyl‐2‐picrylhydrazyl) radical scavenging and deoxyribose damage protection assays, and (b) in vivo, by effects on lipid peroxidation. Terminalia arjuna showed significant DPPH radical scavenging activity with EC50 8.3 ± 0.3 Mg/mL (similar to L‐ascorbic acid). The potency of this activity was much lower in Cassia fistula (EC50 = 59.0 ± 2.7 Mg/mL). The other seven extracts demonstrated no such activity in the concentration range tested. In the deoxyribose damage protection assay, T. arjuna> demonstrated no significant effect in the concentration range 0–20 Mg/mL, but above ­20 Mg/mL concentration (20–125 Mg/mL), a pro‐oxidant activity was observed (although markedly less than demonstrated by L‐ascorbic acid). A similar trend was observed with Vitex negundo. In contrast, C. fistula afforded a 30% protection against such damage at 125 Mg/mL concentration. Other plant extracts did not show any activity in this assay. At a dose of 90 mg/kg (single dose) T. arjuna, cardiac lipid peroxidation in male Wistar rats was reduced by 38.8% ± 2.6% (p<0.05) whereas the reduction was only 11.6% ± 3.5% in the case of C. fistula even at a dose of 120 mg/kg.

Of all the plants tested, T. arjuna demonstrated the highest antioxidant activity. Overall results show that only some plants used in the therapy of cardiovascular disease exert their beneficial effects via antioxidant activity. Copyright © 2001 John Wiley & Sons, Ltd.
Statistical process monitoring using an empirical Bayes multivariate process control chart
Authors: Feltz Carol J. , Shiau Jyh‐Jen Horng
Published: August 2002

In this paper, we describe the theory underlying an empirical Bayesian approach to monitoring two or more process characteristics simultaneously. If the data is continuous and multivariate in nature, often the multivariate normal distribution can be used to model the process. Then, using Bayesian theory, we develop techniques to implement empirical Bayes process monitoring of the multivariable process. Lastly, an example is given to illustrate the use of our techniques. Copyright © 2001 John Wiley & Sons, Ltd.
Assessment of a capability index sensitive to skewness
Authors: Nahar P. C. , Hubele N. F. , Zimmer L. S.
Published: August 2002

For many quality characteristics, such as circularity, cylindricity, straightness and flatness, positive skewness in the inspection data is the norm, and, in fact, is desirable. Summarizing the process performance using such data in conjunction with capability indices has recently received a considerable amount of attention, with new indices being proposed and compared for usefulness and accuracy. This paper is intended to contribute to this growing discussion, and to add a unique focus. In particular, this investigation concentrates on one form of a neoclassical index, the Cs index, originally proposed to be sensitive to skewness and to decrease in value as the skewness increased in the underlying distribution of the data. In other words, ‘skewness is badness’. Looking at this index from an altered perspective, the possibility that this index could serve a useful purpose in summarizing process performance for such non‐normal processes by merely changing its interpretation or slightly changing its form is considered. Hence, actual data from circularity measurements are used to identify a relevant group of distributions, and then the accuracy of Cs is investigated along with its modified version for this group of distributions. In particular, this investigation includes several Rayleigh and gamma distributions for various sample sizes and reports on the bias of the proposed estimators. These findings indicate that such a modified index has some useful attributes in reflecting process performance, with respect to the percentage of non‐conformance and the accuracy for relatively large samples. Copyright © 2001 John Wiley & Sons, Ltd.
Interaction of acetonitrile with alkaline metal cations: A density functional, coupled‐cluster, and quadratic configuration interaction study
Authors: Pejov Ljupčo
Published: August 2002

A systematic quantum chemical study of CH3CN and its CH3CNM+ 1:1 model adducts (M+∈{Li+, Na+}) is presented, with respect to binding energetics, structural and vibrational force field changes. Several gradient‐corrected density functional levels of theory were employed (of both “pure” and “hybrid” character), together with the coupled cluster including double substitutions from the Hartree–Fock determinant (CCD) and quadratic configuration interaction including single and double substitutions (QCISD) methods [with the rather large 6‐311G(d,p) basis set], and their performances compared. The binding energy decompositions according to the Kitaura–Morokuma scheme and the reduced variational space self‐consistent field (RVS‐SCF) method have shown that the electrostatic plus polarization interaction terms are primarily responsible for overall stabilization, while the charge‐transfer term is negligibly small and virtually identical for both adducts. The computed harmonic vibrational frequencies for acetonitrile correlate excellently with the experimental ones (r2>0.9998 for almost all cases, while for the BLYP level, r2=1). It is shown for the first time that the experimentally observed blue shifts of the νCN mode are caused even by formation of 1:1 adducts, contrary to the previously accepted opinions. The CCD and QCISD, as well as the BPW91 and BP86 levels of theory predict almost excellently the νCN mode blue shift upon adduct formation, while the BLYP and B3LYP levels perform significantly poorer. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
On the relationship between the one‐electron and Bohm's quantum potential
Authors: Kohout M.
Published: August 2002

The one‐electron potential, derived from the electron density, is a three‐dimensional function, whereas Bohm's quantum potential depends on the spatial coordinates of all involved electrons. To analyze the relationship between the two potentials in the many‐electron case, first the dimensionality of the quantum potential needs to be reduced to match that of the one‐electron potential. A possible approach for such dimensionality reduction by calculating the expectation value of the quantum potential over all but one electron, using the factorization of the real part of the wave function into a marginal and conditional function is presented, and a relation between such three‐dimensional local quantum potential and the one‐electron potential is given. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
GRECP/MRD‐CI calculations on the Hg atom and HgH molecule
Authors: Mosyagin N. S. , Titov A. V. , Buenker R. J. , Liebermann H.‐P. , Alekseyev A. B.
Published: August 2002

Multireference single‐ and double‐excitation configuration interaction (MRD‐CI) calculations of transition energies for the Hg atom and spectroscopic constants for the HgH molecule are carried out with the generalized relativistic effective core potential (GRECP) method. A new selection criterium for the reference configurations is discussed. The calculated spectroscopic constants are compared with experimental data and results of calculations of other groups. Improvement of accuracy is mainly observed for bond lengths from the GRECP/MRD‐CI calculations (without applying the T = 0 correction) with respect to the results of other groups. Analysis of the quality of the approximations employed is carried out. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Computed electrostatic potentials and average local ionization energies on the molecular surfaces of some tetracyclines
Authors: Hussein Wedad , Walker Christopher G. , Peralta‐Inga Zenaida , Murray Jane S.
Published: August 2002

The electrostatic potentials and average local ionization energies computed on the molecular surfaces of four tetracyclines have been investigated with the objective of identifying common features as well as subtle differences that may be related to their biological activities. The four are the parent molecule tetracycline, chlortetracycline, oxytetracycline, and doxycyline. The calculations were carried out at the HF/STO‐3G*//STO‐3G* level. Our electrostatic potential results show that each molecule has a large negative region that extends along its lower portion, consistent with its ability to complex Ca2+ and Mg2+ ions. Although the surface electrostatic potentials of the four tetracyclines show many similarities, our statistical measure of local polarity allows us to label doxycycline as the one with the lowest degree of local polarity, consistent with its longer half‐life in vivo. The regions in the tetracyclines with the most reactive electrons are the amide nitrogen lone pairs and certain carbons of the outermost rings. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 160–169, 2001
Cumulative coordinates for approximations of high‐order atomic multipole moments in aluminosilicate and aluminophosphate sieves*
Authors: Larin A. V. , Vercauteren D. P.
Published: August 2002

A scheme to obtain approximate analytical functions for the atomic distributed multipole moments of the crystallographically different atoms within aluminosilicate and aluminophosphate sieves is discussed. Respective atomic multipole moments are derived within the CRYSTAL95 ab initio periodic Hartree–Fock code with different basis sets, from minimal STO‐3G to 6‐21G*. In order to illustrate the possible applications, distributed analyses are carried out for various structural models from all‐siliceous zeolites and aluminophosphates with ratio Al/P=1 to hydrogen forms of aluminosilicates. Simple approximate forms based on charge and geometry coordinates are proposed for the high‐order moments of each atom, which are further required for the calculation of the electrostatic field within the structures. The possibility to use this analytical approach to evaluate the electrostatic field within embedded cluster models is also shortly discussed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 70–85, 2001
Protein matrix local fluctuations and substrate binding in HRPC: A proposed dynamic electrostatic sampling method
Authors: Schay Gusztav , Galantai Rita , Laberge Monique , Fidy Judit
Published: August 2002

Horseradish peroxidase C is an oxidoreductase which catalyzes in plant roots the oxidation of a remarkably wide variety of aromatic compounds by H2O2. The recently available X‐ray structures of the enzyme bound to aromatic substrates are not indicative of significant structural rearrangements as a result of substrate binding when compared to the structure of the unbound enzyme. Our most recent spectral hole‐burning studies on HRPC fluorescent derivatives provided direct experimental evidence indicative of different fields experienced at the heme as a result of substrate binding which can only originate in the protein matrix in which the heme is embedded. In this report, we present results on modeling the fluctuations of these protein matrix electrostatic rearrangements using a combination of molecular dynamics and electrostatic conformational sampling to compare the binding of BHA and NHA to HRPC and to the derivative used in our experimental studies. Our initial results suggest that HRPC does undergo conformational rearrangement on binding aromatic substrates, but of an electrostatic nature, as opposed to major conformational structural changes. This implies that the high versatility of substrate binding in horseradish peroxidase could be due to an electrostatic dynamic selectivity mediated by small‐amplitude internal protein matrix motions. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 290–301, 2001
Self‐association of an amphipathic helix peptide inhibitor of HIV‐1 integrase assessed by electro spray ionization mass spectrometry in trifluoroethanol/water mixtures
Authors: Fermandjian S. , Maroun R. S. , Amekraz B. , Jankowski C. K.
Published: August 2002

Establishing the auto‐associative properties of a molecule in solution can be important for determination of its structure and function. EAA26 (VESMNEELKKIIAQVRAQAEHLKTAY) has been designed to inhibit HIV‐1 integrase via formation of a stable coiled‐coil structure with a nearly homologous segment in the enzyme. The latter catalyzes the permanent incorporation of a DNA copy of the retrovirus genome into host cell DNA, and is thus essential to the life of the retrovirus. This makes integrase an obvious drug target in the therapy of AIDS. The present work has demonstrated, using electrospray ionization mass spectrometry (ESI‐MS), that EAA26 is monomeric in pure water, and tetrameric and dimeric at respectively low and medium concentrations of 2,2,2‐trifluoroethanol (TFE), and again monomeric at higher TFE concentrations. Thus, the apolar solvent TFE may contribute to either stabilization or disruption of the intermolecular hydrophobic contacts depending on its concentration in aqueous solution. Previous NMR and ultracentifugation results are thus confirmed, indicating the reliability of ESI‐MS for defining the self‐association state of biologically relevant peptides in both water and organic‐water solutions. Copyright © 2001 John Wiley & Sons, Ltd.
Collision‐induced dissociation of MCl+ adducts (M = Mg, Mn, Zn, Co, Ni and Cu) and Cu+ and Ag+ adducts of dithioalkyl ketene acetals
Authors: Madhusudanan K. P. , Bhat B. A. , Suryawanshi S. N.
Published: August 2002

Electrospray ionization mass spectra of equimolar solutions of dithioalkyl ketene acetals 1 and 2 and metal chlorides (MgCl2, MnCl2, ZnCl2, CoCl2, NiCl2 and CuCl2) produced abundant ligated metal ion adducts [1 + MCl]+ and [2 + MCl]+. In addition, CuCl2 also gave rise to Cu+ adducts. The ligated metal ion adducts upon collision‐induced dissociation (CID) showed characteristic fragmentation pathways reflecting the favoured site of coordination. The results show that MgCl+ prefers oxygen over sulfur, whereas the reverse is true for ZnCl+ adducts, exemplified by the preferred fragmentation of [1 + MgCl]+ as elimination of MgCl(OH), while that of [1 + ZnCl]+ is expulsion of ZnCl(SCH3). Co and Ni chloride adducts tend to give stable metal coordinated species. Cleavage of the dithiolane ring followed by elimination of C2H4S is the preferred pathway during the CID of [2 + MCl]+ adducts. The CuCl+ adducts of 1 and 2 showed reduction of Cu(I) to Cu(0) resulting in the M+· ions of 1 and 2. Abstraction of .CH3 resulting in elimination of CuCH3 was observed during CID of Cu+ adducts of 1 and 2. A comparative study of the corresponding Ag+ adducts revealed a similar behaviour. Copyright © 2001 John Wiley & Sons, Ltd.
Infrared matrix‐assisted laser desorption/ionization of polycyclic aromatic hydrocarbons with a sulfolane matrix
Authors: Jackson Shelley N. , Murray Kermit K.
Published: August 2002

Infrared matrix‐assisted laser desorption/ionization (IR‐MALDI) of the polyaromatic hydrocarbons (PAHs) anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene was performed using a 10.6‐µm CO2 laser and a liquid matrix. Sulfolane (tetrahydrothiophene 1,1‐dioxide) was found to be an effective matrix for PAH ionization: mass spectra obtained with a sulfolane matrix contain an intense molecular ion peak; interference from PAH fragment and matrix peaks is negligible in all cases. The main limitation of the sulfolane matrix is sample evaporation after 3 to 5 min in vacuum. This sample lifetime can be increased to between 15 and 30 min using a 2:1 (v/v) mixture of sulfolane and glycerol, but the resulting spectra have greater matrix interference and decreased shot‐to‐shot signal stability. Copyright © 2001 John Wiley & Sons, Ltd.
Use of matrix‐assisted laser desorption/ionization time‐of‐flight mass mapping and nanospray liquid chromatography/electrospray ionization tandem mass spectrometry sequence tag analysis for high sensitivity identification of yeast proteins separated by two‐dimensional gel electrophoresis
Authors: Poutanen Marjo , Salusjärvi Laura , Ruohonen Laura , Penttilä Merja , Kalkkinen Nisse
Published: August 2002

Current analytical techniques in protein identification by mass spectrometry are based on the generation of peptide mass maps or sequence tags that are idiotypic for the protein sequence. This work reports on the development of the use of mass spectrometric methods for protein identification in research on metabolic pathways of a genetically modified strain of the baker's yeast Saccharomyces cerevisiae. This study describes the use of matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass mapping and liquid chromatography/quadrupole time‐of‐flight electrospray ionization tandem mass spectrometry (LC/Q‐TOF‐ESI‐MS/MS) sequence tag analysis in identification of yeast proteins separated by two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE). The spots were selected for analysis in order to collect information for future studies, to cover the whole pI range from 3 to 10, and to evaluate information from spots of different intensities. Mass mapping as a rapid, high‐throughput method was in most cases sensitive enough for identification. LC/MS/MS was found to be more sensitive and to provide more accurate data, and was very useful when analyzing small amounts of sample. Even one sequence tag acquired by this method could be enough for unambiguous identification, and, in the present case, successfully identified a point mutation. Copyright © 2001 John Wiley & Sons, Ltd.
The nature of collision‐induced dissociation processes of doubly protonated peptides: comparative study for the future use of matrix‐assisted laser desorption/ionization on a hybrid quadrupole time‐of‐flight mass spectrometer in proteomics
Authors: Cramer R. , Corless S.
Published: August 2002

Comparative MS/MS studies of singly and doubly charged electrospray ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) precursor peptide ions are described. The spectra from these experiments have been evaluated with particular emphasis on the data quality for subsequent data processing and protein/amino acid sequence identification. It is shown that, once peptide ions are formed by ESI or MALDI, their charge state, as well as the collision energy, is the main parameter determining the quality of collision‐induced dissociation (CID) MS/MS fragmentation spectra of a given peptide. CID‐MS/MS spectra of singly charged peptides obtained on a hybrid quadrupole orthogonal time‐of‐flight mass spectrometer resemble very closely spectra obtained by matrix‐assisted laser desorption/ionization post‐source decay time‐of‐flight mass spectrometry (MALDI‐PSD‐TOFMS). On the other hand, comparison of CID‐MS/MS spectra of either singly or doubly charged ion species shows no dependence on whether ions have been formed by ESI or MALDI. This observation confirms that, at the time of precursor ion selection, further mass analysis is effectively decoupled from the desorption/ionization event. Since MALDI ions are predominantly formed as singly charged species and ESI ions as doubly charged, the associated difference in the spectral quality of MS/MS spectra as described here imposes direct consequences on data processing, database searching using ion fragmentation data, and de novo sequencing when ionization techniques are changed. Copyright © 2001 John Wiley & Sons, Ltd.
Alkaline liquid chromatography/electrospray ionization skimmer collision‐induced dissociation mass spectrometry for phosphopeptide screening
Authors: Beck Alexander , Deeg Martin , Moeschel Klaus , Schmidt Eckhart K. , Schleicher Erwin D. , Voelter Wolfgang , Häring Hans U. , Lehmann Rainer
Published: August 2002

A rapid on‐line method for the identification of phosphorylated peptides in enzymatic protein digests by specific marker ion signals is described. In our study we investigated the use of alkaline conditions together with a previously described method for selective and sensitive detection of phosphopeptide ions combining high‐performance capillary liquid chromatography (LC) and electrospray ionization mass spectrometry (ESI‐MS).1,,
2 Phosphorylation‐specific marker ions (m/z 79, PO3−, and m/z 97, H2PO4−) were generated by skimmer collision‐induced dissociation (sCID) in the negative‐ion mode. The method was evaluated and validated for mono‐phosphorylated synthetic peptides using different alkaline pH values and CID offsets. Alkaline conditions (pH 10.5) enhance the generation of phosphopeptide‐specific fragment ions from serine‐ and tyrosine‐phosphorylated peptides, and enable the use of m/z 79 (PO3−) and m/z 97 (H2PO4−) as phosphorylation‐specific marker traces. Note that HPLC separation in trifluoroacetic acid containing solvents impairs the use of m/z 97 (C2F3O− fragment ion at m/z 97) as a phosphorylation‐specific marker. The optimized method was applied for the detection of phosphorylated peptides in a tryptic β‐casein digest. The expected mono‐ and tetra‐phosphorylated peptides were detected and rapidly identified by µLC/ESI‐sCID‐MS and µLC/ESI‐MS analysis. Copyright © 2001 John Wiley & Sons, Ltd.
Femtosecond laser time‐of‐flight mass spectrometry of labile molecular analytes: laser‐desorbed nitro‐aromatic molecules
Authors: Hankin S. M. , Tasker A. D. , Robson L. , Ledingham K. W. D. , Fang X. , McKenna P. , McCanny T. , Singhal R. P. , Kosmidis C. , Tzallas P. , Jaroszynski D. A. , Jones D. R. , Issac R. C. , Jamison S.
Published: August 2002

Femtosecond laser time‐of‐flight mass spectra of solid samples of trinitrobenzene (TNB), trinitrotoluene (TNT) and trinitrophenol (TNP) have been recorded. Desorption of the solid samples was enacted by the fourth harmonic output (266 nm) of a 5 ns Nd:YAG laser. Subsequent femtosecond post‐ionisation of the plume of neutral molecules was achieved using 800 nm laser pulses of 80 fs duration. Mass spectra have been recorded for desorption laser intensities from 2–6 × 109 W cm−2with ionisation laser intensities between 2 × 1014and 6 × 1015 W cm−2. Femtosecond laser ionisation has been shown to be capable of generating precursor and characteristic high‐mass fragment ions for labile nitro‐aromatic molecules commonly used in high‐explosive materials. This feature is critical in the future development of femtosecond laser‐based analytical instruments that can be used for complex molecular identification and quantitative analysis of environmentally important labile molecules. Furthermore, a comparison of femtosecond post‐ionisation mass spectra with standard 70 eV electron impact data has revealed similarities in the spectra and hence the fragmentation processes. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of flavonoid constituents from leaves of Acanthopanax senticosus Harms by electrospray tandem mass spectrometry
Authors: Chen Maolian , Song Fengrui , Guo Mingquan , Liu Zhiqiang , Liu Shuying
Published: August 2002

Three known flavonoids, quercetin, quercitrin (quercetin‐3‐0‐rhamnoside) and rutin (quercetin‐3‐0‐rutinoside), have been identified for the first time in the leaves of Acanthopanax senticosus Harms by using electrospray tandem mass spectrometry techniques (ESI−MSn). The flavonoid hyperin (quercetin‐3‐0‐β‐galactoside), already known to be present, was also investigated. The diagnostic fragment ions of the aglycone quercetin were obtained in the ESI−MSn experiments, and a fragmentation mechanism proposed. Copyright © 2002 John Wiley & Sons, Ltd.
Characterisation of combinatorial libraries of mucin‐2 antigen peptides by high‐resolution mass spectrometry
Authors: Windberg Emöke , Hudecz Ferenc , Marquardt Andreas , Sebestyén Ferenc , Kiss Andrea , Bösze Szilvia , Medzihradszky‐Schweiger Hedvig , Przybylski Michael
Published: August 2002

An epitope motif, TX1TX2T, of mucin‐2 glycoprotein was identified by means of a mucin‐2‐specific monoclonal antibody, mAb 994, raised against a synthetic mucin‐derived 15‐mer peptide conjugate. For determination of the epitope sequence recognised with highest affinity by mAb 994, a combinatorial approach was applied using the portioning‐mixing technique excluding Cys. Antibody binding of libraries was most profound when Gln was at the X1 position. Analytical characterisation of the TQTX2T library was conducted by amino acid analysis and matrix‐assisted laser desorption/ionisation time‐of‐flight (MALDI‐TOF) and electrospray ionisation Fourier transform ion cyclotron resonance (ESI‐FTICR) mass spectrometric methods. Control libraries were prepared by mixing 19 individual peptides corresponding to the TQTX2T sequence. Thus, mixtures of 6, 10 and 19 pentapeptides were analysed and compared with the combinatorial mixture. MALDI‐TOFMS was able to detect only partially the components in the 6‐ and 10‐member mixtures, but failed to characterise a more complex 19‐member mixture. In contrast, ESI‐FTICRMS resolved all mixtures of higher complexity and provided direct identification at monoisotopic resolution, such as for a peptide library containing ‘isobaric’ lysine and glutamine (Δm = 0.0364 Da). The results of this study suggest that ESI‐FTICRMS is a powerful tool for characterisation of combinatorial peptide libraries of higher complexity. Copyright © 2002 John Wiley & Sons, Ltd.
Simultaneous separation of 17 inorganic and organic arsenic compounds in marine biota by means of high‐performance liquid chromatography/inductively coupled plasma mass spectrometry
Authors: Kohlmeyer Ute , Kuballa Jürgen , Jantzen Eckard
Published: August 2002

A method using high‐performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP‐MS) has been developed to determine inorganic arsenic (arsenite, arsenate) along with organic arsenic compounds (monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, tetramethylarsonium ion and several arsenosugars) in fish, mussel, oyster and marine algae samples. The species were extracted by means of a methanol/water mixture and a dispersion unit in 2 min, with extraction efficiencies ranging from 83 to 107% in the different organisms. Up to 17 different species were determined within 15 min on an anion‐exchange column, using a nitric acid gradient and an ion‐pairing reagent. As all species are shown in one chromatogram, a clear overview of arsenic distribution patterns in different marine organisms is given. Arsenobetaine is the major compound in marine animals whereas arsenosugars and arsenate are dominant in marine algae. The method was validated with CRM DORM‐2 (dogfish muscle). Concentrations were within the certified limits and low detection limits of 8 ng g−1 (arsenite) to 50 ng g−1 (arsenate) were obtained. Copyright © 2002 John Wiley & Sons, Ltd.
Homocysteine thiolactone and protein homocysteinylation: mechanistic studies with model peptides and proteins
Authors: Hop Cornelis E. C. A. , Bakhtiar Ray
Published: August 2002

In vitro incubations were performed to show that homocysteine thiolactone could generate covalent adducts with model peptides and proteins. MS and MS/MS data suggest that the thiolactone reacts with the side‐chain amino group of lysine residues as well as with the N‐terminal amino group or C‐terminal carboxy group. For larger peptides and proteins, the contribution from the ∈‐amino groups of lysine residues should be predominant. These data could help explain the detrimental effects of elevated levels of homocysteine and homocysteine thiolactone. Copyright © 2002 John Wiley & Sons, Ltd.
Novel direct detection method for quantitative determination of intracellular nucleoside triphosphates using weak anion exchange liquid chromatography/tandem mass spectrometry
Authors: Shi Guoen , Wu Jing‐tao , Li Yu , Geleziunas Romas , Gallagher Karen , Emm Tom , Olah Timothy , Unger Steve
Published: August 2002

A novel analytical method has been developed for direct quantification of intracellular nucleoside triphosphates (NTPs). Lysates of human peripheral blood mononuclear cells (PBMCs) were extracted by protein precipitation, and the filtered extracts were analyzed by weak anion exchange liquid chromatography (WAX‐LC) coupled to detection by mass spectrometry (MS). Compared with ion pairing (IP)‐LC/MS/MS, the only MS‐compatible direct detection method for NTPs currently available, the new method completely avoids the usage of ion‐pairing reagents and has a shorter analytical time of only 2 min. The method was validated and is being used to determine the amount of the triphosphate metabolite of D‐D4FC (DPC817), an investigational HIV nucleoside reverse transcriptase inhibitor (NRTI), in human PBMC samples from clinical studies. By using a PE Sciex API 4000 triple quadrupole instrument operating in positive ion MRM mode, the method was able to achieve a lower limit of quantitation (LLOQ) of 5 fmol/106 cells in samples containing 3 × 106 lysed cells (6 fmol on‐column). With minor adaptation, the method described here may be suitable for analyzing other NTPs. This paper also provides a discussion of the unique retention characteristics of WAX‐LC, the principles of which may prove to be valuable for designing other forms of directly coupled ion‐exchange (IX)‐LC/MS methods suited for high sensitivity quantitative analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of glutathione in spruce needles by liquid chromatography/tandem mass spectrometry
Authors: Guček Marjan , Makuc Simon , Mlakar Anita , Beričnik‐Vrbovšek Julija , Marsel Jože
Published: August 2002

For the determination of glutathione (GSH) and its oxidized form (GSSG) in spruce needles their electrospray mass and MS/MS spectra were recorded with an ion trap mass spectrometer (ITMS, LCQ, Finnigan) and a triple stage quadrupole mass spectrometer (TSQ, Quattro II, Micromass). A study of the stability of GSH in aqueous solutions shows the presence of dimeric and trimeric forms of GSH, as well as GSSG, GSH‐sulfonate and GSH‐sulfinic acid. The same components were also found in extracts of spruce needles. We developed an assay which is suitable for monitoring low concentrations of GSH and similar compounds in plant tissues, employing the sensitivity and specificity of LC/MS/MS. Preliminary results on the mass spectrometric determination of GSH in spruce needles are given. Copyright © 2002 John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization mass spectrometry compatible β‐elimination of O‐linked oligosaccharides
Authors: Huang Yunping , Konse Tomonori , Mechref Yehia , Novotny Milos V.
Published: August 2002

A new β‐elimination procedure has been introduced to cleave O‐linked oligosaccharides from low‐ to sub‐microgram amounts of glycoproteins prior to analysis by mass spectrometry. Borane‐ammonia complex in aqueous ammonia is used as a cleaving solution alternative to the sodium borohydride/sodium hydroxide medium conventionally used in β‐elimination. The procedure results in minimum sample purification, leading to minimal sample loss and consequently an overall enhancement in sensitivity. It was applied successfully in the analysis of bovine fetuin and submaxillary mucin, as well as to a complex bile‐salt‐stimulated lipase glycoprotein isolated from human milk. Copyright © 2002 John Wiley & Sons, Ltd.
Persistence of arboviruses and antiviral antibodies in vertebrate hosts: its occurrence and impacts†
Authors: Kuno Goro
Published: August 2002

The recent isolation of West Nile virus from a bird in mid‐winter in New York immediately raised, as one of a few explanations, the possibility of long‐term persistence of arboviruses in vertebrate hosts. Although it was a highly popular topic for research many years ago, generally it has since been neglected and its meaning under appreciated. This comprehensive survey of literature worldwide uncovered, contrary to the general perception that it is a rather infrequent phenomenon, a large number of important observations involving all groups of arboviruses that have been accumulating over the years without drawing much attention. In this review, the data and observations were analysed in terms of the occurrence, role in natural transmission, mechanisms and genesis of persistence, source of problems in research and impact. The outcome of the analyses clearly demonstrates that asymptomatic, long‐term infection in the absence of viraemia with or without the induction of neutralising antibody, the most frequent characteristics of arboviral persistence, presents a serious question about the validity of some of the past animal experiments that were conducted without the consideration of such a possibility. Likewise, significant impacts are felt on diverse fields ranging from epidemiology to diagnostic virology and from veterinary medicine to agricultural commerce. Published in 2001 by John Wiley & Sons, Ltd.
The group B coxsackieviruses and myocarditis
Authors: Kim Kyung‐Soo , Hufnagel Günter , Chapman Nora M. , Tracy Steven
Published: August 2002

The six serotypes of the group B coxsackieviruses (CVB) are common human enteroviruses linked etiologically to inflammatory cardiomyopathies. This has been demonstrated by molecular detection of enteroviral RNA in human heart tissue, serologic associations with disease, and virus isolation from cases of fulminant myocarditis. The murine model of CVB‒associated myocarditis has demonstrated that CVB can be attenuated through mutations at different genomic sites. Human CVB3 isolates demonstrate varying degrees of cardiovirulence in the murine model; one site of virulence determination has been mapped to domain II of the 5′ non‒translated region. The interplay of CVB replication and the immune response to that replication in the heart is a complex interaction determining the extent to which the virus replication is limited and the degree to which a pathogenic inflammation of cardiac muscle occurs. Studies of CVB3‒induced myocarditis in murine strains lacking subsets of the immune system or genes regulating the immune response have demonstrated a pivotal role of the T cell response to the generation of myocarditis. While CVB are associated with 20–25% of cases of myocarditis or cardiomyopathy, the severity of the disease and the existence of attenuated strains shown to generate protective immunity in animal models indicates that vaccination against the CVBs would be valuable. Copyright © 2001 John Wiley & Sons, Ltd.
Interactions of SV40 large T antigen and other viral proteins with retinoblastoma tumour suppressor
Authors: Lee Changwook , Cho Yunje
Published: August 2002

Simian virus 40 large T antigen, human papilloma virus E7 and adenovirus E1A are all potent oncoproteins that can induce several types of tumours. One of the major functions of these oncoproteins is to interact with the retinoblastoma tumour suppressor protein, Rb, a master switch of the mammalian cell cycle, and to inactivate its function. Rb promotes cell‐cycle arrest by recruiting and regulating proteins involved in the transcription of cell proliferation genes. The binding of viral oncoproteins to Rb disrupts the Rb–E2F complex, a central component in the Rb‐mediated cell‐cycle network. The crystal structures of Rb pocket–viral oncoprotein complexes indicate that the viral proteins recognise a highly conserved region in the Rb pocket through a common motif, LxCxE, and through other unique regions within each viral protein. Although the mechanism of Rb inactivation by viral proteins is not fully understood, information at the atomic level about the interactions between the Rb pocket and viral proteins is providing some insights into how viral proteins dissociate E2F from Rb and thus how they deregulate the cell cycle. Copyright © 2002 John Wiley & Sons, Ltd.
The constant‐Jacobian method for kinematics of a three‐DOF planar micro‐motion stage
Authors: Zhang W. J. , Zou J. , Watson L. G. , Zhao W. , Zong G. H. , Bi S. S.
Published: August 2002

This paper concerns the development of a class of devices that generate end‐effector motion in the
range of less than 100 μm and with sub‐nanometer resolution; in particular, a parallel manipulator
configuration that generates a planar x‐y‐γ motion is considered. The parallel
manipulator is implemented as a compliant mechanism. A problem with parallel manipulators is that the forward
kinematics is usually too complex, which can hinder the implementation of advanced control algorithms. The
contribution of this paper is that a simple method, called the constant‐Jacobian (CJ) method, is
developed based on the pseudo‐rigid body (PRB) approach to compliant mechanisms. The experiment
validates the CJ method. © 2002 John Wiley & Sons, Inc.
The synthesis of planar parallel manipulators with prismatic joints for an optimal, singularity‐free workspace
Authors: Gallant Marise , Boudreau Roger
Published: August 2002

The synthesis of three‐degree‐of‐freedom planar parallel manipulators is performed using
a genetic algorithm. The architecture of a manipulator and its position and orientation with respect to a
prescribed workspace are determined.

The architectural parameters are optimized so that the manipulator's constant‐orientation
workspace is as close as possible to a prescribed workspace. The manipulator's workspace is discretized and
its dexterity is computed as a global property of the manipulator. An analytical expression of the singularity
loci (local null dexterity) can be obtained from the Jacobian matrix determinant, and its intersection
with the manipulator's workspace may be verified and avoided.

Results are shown for different conditions. First, the manipulators' workspaces are optimized for a
prescribed workspace, without considering whether the singularity loci intersect it or not. Then the same type of
optimization is performed, taking intersections with the singularity loci into account. In the following results,
the optimization of the manipulator's dexterity is also included in an objective function, along with the
workspace optimization and the avoidance of singularity loci. Results show that the end‐effector's
location has a significant effect on the manipulator's dexterity. © 2002 John Wiley & Sons,
Inc.
Addendum to ‘avoiding a giant component’
Authors: Bohman Tom , Frieze Alan
Published: August 2002

We take this opportunity, which is kindly provided by the editors, to add a theorem and to correct the proof of one of the lemmas in the article ‘Avoiding a Giant Component’ [Bohman and Frieze, Avoiding a giant component, Random Struct Alg 19 (2001), 75–85]. The subject of the said article is the following guided random process. Let e1, \documentclass{article}\pagestyle{empty}\begin{document}$e^{\prime}_{1}$\end{document}; e2, \documentclass{article}\pagestyle{empty}\begin{document}$e^{\prime}_{2}$\end{document};…;ei, \documentclass{article}\pagestyle{empty}\begin{document}$e^{\prime}_{i}$\end{document};… be a sequence of ordered pairs of edges chosen uniformly at random from the edge set of the complete graph Kn. This sequence is used to form a graph by choosing at stage i, i=1,…, one edge from ei, \documentclass{article}\pagestyle{empty}\begin{document}$e_{i}^{\prime}$\end{document} to be an edge in the graph, where the choice at stage i is based only on the observation of the edges that have appeared by stage i. In Bohman and Frieze [Avoiding a giant component, Random Struct Alg 19 (2001), 75–85], we proved that these choices can be made so that whp (A sequence of events ℰn is said to occur with high probability (whp) if limn→∞Pr(ℰn)=1.), the size of the largest component of the graph formed at stage. 535n, is polylogarithmic in n. Here, we make a correction to that proof and prove that the graph formed at stage cn for any constant c>1 will contain a component of size Ω(n) (regardless of how the edges are chosen at each stage). © 2002 John Wiley & Sons, Inc. Random Struct. Alg., 20, 126–130, 2002
What makes an inquiry‐oriented science teacher? The influence of learning histories on student teacher role identity and practice
Authors: Eick Charles J. , Reed Cynthia J.
Published: August 2002

This paper examines the influence of personal histories on the formation of early role identity as inquiry‐oriented science teachers. Two cases selected from a multicase study of 12 secondary science student teachers are used to illustrate the development of inquiry orientation. These cases represent two extremes in a continuum ranging from didactic practice to successful use of structured inquiry. The role of learners' personal histories on their teaching identity development and implications for preparing inquiry‐based science teachers are discussed. © 2002 Wiley Periodicals, Inc. Sci Ed 86:401–416, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/sce.10020
An analysis of elementary teachers' beliefs regarding the teaching and learning of science
Authors: Levitt Karen E.
Published: August 2002

The purpose of this study was to ascertain the beliefs of elementary teachers regarding the teaching and learning of science and the extent to which the teachers' beliefs were consistent with the philosophy underlying science education reform. Sixteen teachers from two school districts involved in a local systemic initiative for science education reform participated in the study. Each teacher was observed teaching a lesson from the program. The observation served as the context for an interview with the teacher regarding his or her beliefs about the teaching and learning of science. One overarching belief emerged: Teachers believe that the teaching and learning of science should be student centered. Five patterns of teachers' responses support this characterization of the teachers' belief. Although varying gaps exist between the teachers' beliefs and the principles of reform, the teachers' beliefs suggest that the teachers are moving in a direction consistent with science education reform. A modified case study of three teachers represents the patterns of beliefs expressed by teachers. © 2001 John Wiley & Sons, Inc. Sci Ed 86:1–22, 2001.
Interface analysis with the three‐dimensional atom probe
Authors: Miller M. K.
Published: August 2002

The application of the technique of atom probe tomography to the atomic scale characterization of interfaces and surface films is described. The three‐dimensional atom probe determines the coordinates and elemental identities of the atoms in a small volume of a sample with near‐atomic precision. The types of analyses that may be performed on interfaces are demonstrated by examples taken from a variety of materials, including neutron‐irradiated pressure‐vessel steel welds, superalloys, surface films and model alloys. Published in 2001 by John Wiley & Sons, Ltd.
Peak or centroid — which parameter is better suited for quantifying apparent marker locations in low‐energy sputter depth profiling with reactive primary ion beams?
Authors: Wittmaack K. , Hammerl E. , Eisele I. , Patel S. B.
Published: August 2002

Silicon samples containing narrow boron markers were depth profiled using normally incident 0.25–1 keV O2+ ion beams in combination with secondary ion mass spectrometry (SIMS). The profiles revealed significant deviations from ideal delta distributions, either as tails or shoulders. All tracer profiles exhibited the well‐known apparent shift towards the surface, which is due to the initial decrease in erosion rate. The peak positions, $\catcode`@=11\def\curvedhat#1{\vbox{\offinterlineskip\ialign{##\crcr\hfil$\scriptscriptstyle\frown$\hfil\crcr\hfil{#1}\hfil\crcr}}}\curvedhat{z}$, showed a much more pronounced non‐linear energy‐dependent shift than the centroids, 〈z〉, up to a factor of 2 stronger. To evaluate the form of measured profiles, a reduced shape parameter is defined as Δ = 〈z〉 − $\catcode`@=11\def\curvedhat#1{\vbox{\offinterlineskip\ialign{##\crcr\hfil$\scriptscriptstyle\frown$\hfil\crcr\hfil{#1}\hfil\crcr}}}\curvedhat{z}$. For ideal deltas, this parameter can be calculated using the analytical resolution function (rf) after Dowsett et al. Depending on the orientation and magnitude of the tracer distortions, the measured values of Δ differed from Δrf by up to 0.8 nm. This difference is attributed to the fact that the ‘weight’ of the distortions gives rise to a corresponding change of 〈z〉. The results imply that (relative) marker locations are determined more safely from $\catcode`@=11\def\curvedhat#1{\vbox{\offinterlineskip\ialign{##\crcr\hfil$\scriptscriptstyle\frown$\hfil\crcr\hfil{#1}\hfil\crcr}}}\curvedhat{z}$ than from 〈z〉. Copyright © 2001 John Wiley & Sons, Ltd.
Investigation of the electrostatic forces in scanning probe microscopy at low bias voltages
Authors: Patil Shivprasad , Dharmadhikari C. V.
Published: August 2002

The electrostatic force between a gold tip and an atomically flat highly oriented pyrolytic graphite substrate has been measured as a function of tip– sample separation distance for low bias voltages (<1 v). The experiments involve phase‐sensitive detection of the reflected laser beam off a stiff oscillating cantilever as it approaches the sample. The results are compared with the theoretical model in which the tip– sample geometry is described by confocal hyperboloids of revolution. The general behaviour of the force curve was found to be in agreement with theoretical expectations only for distances of >600 Å. The deviations at smaller distances probably could be due to extraneous material such as graphite nanoflakes or a conducting liquid column present between tip and sample. The results have direct bearing on understanding the interaction forces in scanning probe microscopy techniques in which tip– sample junctions are biased. Copyright © 2002 John Wiley & Sons, Ltd.
XPS of chemically modified low‐density polyethylene surfaces: observations on curve‐fitting the C 1s spectrum
Authors: Briggs D. , Fairley N.
Published: August 2002

The curve‐fitting of the complex C 1s envelopes (obtained under high‐energy‐resolution XPS conditions) resulting from the surface chemical modification of low‐density polyethylene has been investigated. The main problem is modelling of the dominant, asymmetric component due to unmodified hydrocarbon. Two approaches have been compared, namely the use of a full (four‐component) vibrational progression or a single peak with a lineshape recently introduced by Gelius. As well as goodness of fit criteria, the agreement between the measured O 1s intensity and that predicted from the intensities of the high‐binding‐energy C 1s components (from oxygen‐containing functional groups) was used in the assessment. Under the relatively low‐level, but practically relevant, modification conditions studied, the two approaches are equally effective. However, they can give rise to significant differences in the relative intensities of high‐binding‐energy components. Broadening of the various components as a function of treatment also has been studied. Copyright © 2002 John Wiley & Sons, Ltd.