bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaerobic fitness in children with asthma: Adaptation to maximal intermittent short exercise
Authors: Counil F.‐P. , Karila C. , Varray A. , Guillaumont S. , Voisin M. , Préfaut C.
Published: August 2002

Nineteen asthmatic boys (aged 13.4 years, 25–75 percentile: 11.5–15.1 years) performed short bouts of maximal exercise (force‐velocity test) to test their anaerobic fitness and tolerance of maximal anaerobic exercise. Fourteen healthy boys (aged 13.9 years, 25–75 percentile: 11.6–15.7 years) matched for anthropometric characteristics including lean body mass (LBM), pubertal stage, and weekly physical activity formed a control group. The maximal anaerobic power (Wana) was measured during the force‐velocity test. The maximal oxygen uptake (V′) was assessed during a standard graded exercise test. Pre‐ and post‐exercise pulmonary function was measured by body plethysmography.

The asthmatic children exhibited lower Wana than the control group (8.2 watt·kg−1 LBM, 25–75 percentile: 7.55–10.6 vs. 11.3 watt·kg−1 LBM, 25–75 percentile: 9.46–14.1; P = 0.01). V′ was also diminished in the asthmatic group (P = 0.01). Multiple stepwise regression models revealed that Tanner's score (P < 0.001) and the diagnosis of asthma (P < 0.01) were the best predictors of Wana.

In conclusion, a diminished anaerobic fitness could contribute to the overall exercise limitation in asthmatic children. Pediatr Pulmonol. 2001; 31:198–204. © 2001 Wiley‐Liss, Inc.
Glucocorticoids and lung development in the fetus and preterm infant
Authors: Bolt Roel J. , van Weissenbruch M.M. , Lafeber H.N. , Delemarre‐van de Waal H.A.
Published: August 2002

During the final prenatal period of fetal lung development in humans, important maturational processes occur, including the production of surfactant necessary to decrease surface tension at the air‐liquid interface of the alveoli. During early gestation, the glucocorticoid receptor is expressed in the fetal lung, and glucocorticoids stimulate the production of surfactant‐associated proteins and increase phospholipid synthesis by enhancing the activity of phosphatidylcholine. Other glucocorticoid‐induced effects may include stimulation of cell maturation and differentiation, inhibition of DNA synthesis, changes in interstitial tissue components, stimulation of antioxidant enzymes, and regulation of pulmonary fluid metabolism. Recently, it was suggested that glucocorticoids are also important in postnatal pulmonary development, and may be related to the development of neonatal lung disease in preterm infants. Surfactant deficiency that can be prevented by antenatal corticosteroid treatment causes infant respiratory distress syndrome and requires mechanical ventilation. Ventilation by itself or in combination with high levels of oxygen, fluid overload, pulmonary infections, sepsis, and air leak syndrome causes an acute pulmonary inflammatory reaction that may result in chronic lung disease or bronchopulmonary dysplasia. Glucocorticoids are effective in the treatment of chronic lung disease of prematurity and regulate the inflammatory response by the interaction with transcription factors such as nuclear factor κB and activated protein 1. Indeed, inflammatory cells and the levels of chemokines and cytokines in bronchoalveolar fluid decrease after dexamethasone treatment. However, treatment of fetuses and preterm infants with repeated and/or high doses of corticosteroids may have considerable long‐term side effects on somatic, brain, and lung growth. The difficult balance between short‐term gain and the possible long‐term side effects of glucocorticoids in preterms remains a difficult issue. Pediatr Pulmonol. 2001; 32:76–91. © 2001 Wiley‐Liss, Inc.
Effects and characterization of paracrine factors produced by human prostate stromal cells in bioassays using rat Sertoli cells, LNCaP tumor cells, and cultured prostate epithelial cells
Authors: Goossens Karine , Deboel Ludo , Swinnen Johannnes V. , De Gendt Karel , Rombauts Wilfried , Verhoeven Guido
Published: August 2002

BACKGROUND

Prostatic stroma affects both proliferation and differentiation of epithelial cells but the factors involved remain poorly understood. In order to identify and characterize potential paracrine mediators, we studied the effects of human prostate fibroblast‐conditioned media (PFCM) in three bioassay systems.

METHODS

The first bioassay uses transferrin secretion by cultured rat Sertoli cells as an endpoint for differentiating activity. Factors active in this (heterologous) assay were compared to PModS, a mediator of mesenchymal–epithelial interactions in the testis, also produced by rat prostate stromal cells. The two other (homologous) bioassays use LNCaP tumor cells or subcultured human prostate epithelial cells (PEC) as targets. Differentiation is evaluated by prostate‐specific antigen (PSA) secretion and reverse transcriptase‐polymerase chain reaction (RT‐PCR) for a number of markers of epithelial function. Proliferation is assayed by measurements of DNA and thymidine incorporation.

RESULTS

PFCM markedly stimulates transferrin production by Sertoli cells. The main factor(s) involved are acid stable and bind to heparin. However, both their size (approximately 37 kDa) and their behavior on reversed‐phase chromatography differ from that of PModS. Although PFCM increases total RNA content of LNCaP, it does not increase or restore differentiated function of LNCaP or PEC. Proliferative effects are observed in LNCaP and these effects cannot be neutralized by an antiserum directed against basic fibroblast growth factor (bFGF). Antiproliferative effects are observed in PEC and these effects are largely due to transforming growth factor‐β (TGF‐β).

CONCLUSIONS

PFCM provokes differentiating effects in a Sertoli cell bioassay, but unlike with rat stromal cells, the factor(s) involved differ from PModS. In the two homologous systems studied, differentiating effects could not be demonstrated and discordant effects were noted on proliferation. Various bioassay systems will be required to identify the spectrum of mediators present in PFCM. Prostate 48:104–117, 2001. © 2001 Wiley‐Liss, Inc.
Silk fibroin: Structural implications of a remarkable amino acid sequence
Authors: Zhou Cong‐Zhao , Confalonieri Fabrice , Jacquet Michel , Perasso Roland , Li Zhen‐Gang , Janin Joel
Published: August 2002

The amino acid sequence of the heavy chain of Bombyx mori silk fibroin was derived from the gene sequence. The 5,263‐residue (391‐kDa) polypeptide chain comprises 12 low‐complexity “crystalline” domains made up of Gly–X repeats and covering 94% of the sequence; X is Ala in 65%, Ser in 23%, and Tyr in 9% of the repeats. The remainder includes a nonrepetitive 151‐residue header sequence, 11 nearly identical copies of a 43‐residue spacer sequence, and a 58‐residue C‐terminal sequence. The header sequence is homologous to the N‐terminal sequence of other fibroins with a completely different crystalline region. In Bombyx mori, each crystalline domain is made up of subdomains of ∼70 residues, which in most cases begin with repeats of the GAGAGS hexapeptide and terminate with the GAAS tetrapeptide. Within the subdomains, the Gly–X alternance is strict, which strongly supports the classic Pauling–Corey model, in which β‐sheets pack on each other in alternating layers of Gly/Gly and X/X contacts. When fitting the actual sequence to that model, we propose that each subdomain forms a β‐strand and each crystalline domain a two‐layered β‐sandwich, and we suggest that the β‐sheets may be parallel, rather than antiparallel, as has been assumed up to now. Proteins 2001;44:119–122. © 2001 Wiley‐Liss, Inc.
Adenine recognition: A motif present in ATP‐, CoA‐, NAD‐, NADP‐, and FAD‐dependent proteins
Authors: Denessiouk Konstantin A. , Rantanen Ville‐Veikko , Johnson Mark S.
Published: August 2002

Adenosine triphosphate (ATP) plays an essential role in energy transfer within the cell. In the form of NAD, adenine participates in multiple redox reactions. Phosphorylation and ATP‐hydrolysis reactions have key roles in signal transduction and regulation of many proteins, especially enzymes. In each cell, proteins with many different functions use adenine and its derivatives as ligands; adenine, of course, is present in DNA and RNA. We show that an adenine binding motif, which differs according to the backbone chain direction of a loop that binds adenine (and in one variant by the participation of an aspartate side‐chain), is common to many proteins; it was found from an analysis of all adenylate‐containing protein structures from the Protein Data Bank. Indeed, 224 protein–ligand complexes (86 different proteins) from a total of 645 protein structure files bind ATP, CoA, NAD, NADP, FAD, or other adenine‐containing ligands, and use the same structural elements to recognize adenine, regardless of whether the ligand is a coenzyme, cofactor, substrate, or an allosteric effector. The common adenine‐binding motif shown in this study is simple to construct. It uses only (1) backbone polar interactions that are not dependent on the protein sequence or particular properties of amino acid side‐chains, and (2) nonspecific hydrophobic interactions. This is probably why so many different proteins with different functions use this motif to bind an adenylate‐containing ligand. The adenylate‐binding motif reported is present in “ancient proteins” common to all living organisms, suggesting that adenine‐containing ligands and the common motif for binding them were exploited very early in evolution. The geometry of adenine binding by this motif mimics almost exactly the geometry of adenine base‐pairing seen in DNA and RNA. Proteins 2001;44:282–291. © 2001 Wiley‐Liss, Inc.
A monoclonal antibody‐based ELISA for the analysis of the insecticide flucythrinate in environmental and crop samples
Authors: Nakata Masanobu , Fukushima Azusa , Ohkawa Hideo
Published: August 2002

A competitive enzyme‐linked immunosorbent assay (ELISA) has been developed for the detection of the insecticide flucythrinate in environmental and food samples. Two types of haptens, the acid moiety that is the hydrolyzed product of flucythrinate, and the carboxylated propyl derivative of the alcohol moiety, were used to prepare monoclonal antibodies (MAbs). Five MAbs, which raised against the former hapten, were reactive with flucythrinate. Among them, MAb F1A27‐4 showed the highest activity toward flucythrinate, and did not cross‐react with other pyrethroids such as cycloprothrin, fenvalerate, fluvalinate, etofenprox and silafluofen. The assay conditions of indirect competitive ELISA with MAb F1A27‐4 were studied to optimize the detection of flucythrinate in environmental and food samples. Incubation at 4 °C in the assay buffer, pH 8, with 300 mM sodium chloride improved the sensitivity. The addition of rabbit serum albumin or rabbit antiserum and the presence of 50 ml litre−1 of methanol reduced matrix effects of the samples. Under optimized conditions, the ELISA detected flucythrinate spiked in water, soil, and extracts of apple and tea samples down to 10 mg litre−1, 0.2 mg litre−1, 0.3 mg litre−1 and 0.3 mg litre−1, respectively. The mean recovery and CV ranged from 91% to 120% and from 5% to 12%, respectively. The ELISA results in apple samples correlated well with those from LC–MS analysis (r2 = 0.99, n  = 12).

© 2001 Society of Chemical Industry
Resistance of a soybean cell line to oxyfluorfen by overproduction of mitochondrial protoporphyrinogen oxidase
Authors: Warabi Eiji , Usui Kenji , Tanaka Yoshiyuki , Matsumoto Hiroshi
Published: August 2002

The diphenyl ether herbicide oxyfluorfen (2‐chloro‐4‐trifluoromethylphenyl 3‐ethoxy‐4‐nitrophenyl ether) inhibits protoporphyrinogen oxidase (Protox) which catalyzes the oxidation of protoporphyrinogen IX (Protogen) to protoporphyrin IX (Proto IX), the last step of the common pathway to chlorophyll and haeme biosynthesis. We have selected an oxyfluorfen‐resistant soybean cell line by stepwise selection methods, and the resistance mechanism has been investigated. No growth inhibition was observed in resistant cells at a concentration of 10−7 M oxyfluorfen, a concentration at which normal cells did not survive. While the degree of inhibition of total extractable Protox by oxyfluorfen was the same in both cell types, the enzyme activity in the mitochondrial fraction from non‐treated resistant cells was about nine‐fold higher than that from normal cells. Northern analysis of mitochondrial Protox revealed that the concentration of mitochondrial Protox mRNA was much higher in resistant cells than that in normal cells. There were no differences in the absorption and metabolic breakdown of oxyfluorfen. The growth of resistant cells was also insensitive to oxadiazon [5‐tert‐butyl‐3‐(2,4‐dichloro‐5‐isopropoxyphenyl)‐1,3,4‐oxadiazol‐2‐(3H)‐one], the other chemical class of Protox inhibitor. Therefore, the resistance of the selected soybean cell line to oxyfluorfen is probably mainly due to the overproduction of mitochondrial Protox.

© 2001 Society of Chemical Industry
Fate of spinosad in litter and soils of a white spruce plantation in central Ontario
Authors: Thompson Dean G , Harris Brenda J , Buscarini Teresa M , Chartrand Derek T
Published: August 2002

Spinosad is a natural insecticide with potential as a novel biorational control agent for spruce budworm (Choristoneura fumiferana [Clem]), the most destructive insect defoliator of spruce and balsam fir in Canada. Concurrent terrestrial fate experiments were conducted under full coniferous canopy and in a natural opening of a mature white spruce (Picea glauca [Moench]) plantation of central Ontario to examine the fate and persistence of spinosad in the forest floor and underlying soils. Mean initial residues of spinosyn A and D were approximately 0.2 and 0.02 µg g−1, respectively, in thatch and exposed soils, but were substantially higher, 2.72 and 0.36 µg g−1, in litter under coniferous canopy. Results demonstrated that spinosad residues in spruce litter, graminaceous thatch and exposed sandy loam soils dissipated rapidly, following hyperbolic or exponential decline models. Dissipation time (DT50) values ranged from 2.0 to 7.8 days, depending on matrix and experimental conditions. Transient increases in demethylated metabolite residues confirmed that the parent product was degraded in situ. No evidence of vertical mobility of any of the analytes was observed.

© 2002 Society of Chemical Industry
Synthesis of biotin conjugates of the antifungal compound cymoxanil
Authors: Evans Karen Anderson , Kane Charles T , Tice Colin M
Published: August 2002

Biotin conjugates are of considerable value in investigating the mode of action of biologically active compounds. Two biotin conjugates related to the antifungal compound cymoxanil [1‐(2‐cyano‐2‐methoximinoacetyl)‐3‐ethyl urea] were prepared as the first step in an effort to employ display cloning to identify the compound's target site. In the first conjugate, prepared in five steps, the biotin moiety was attached at the position occupied by the ethyl group in cymoxanil. In the second conjugate, prepared in four steps, the biotin moiety was attached through the oxime functional group.

© 2002 Society of Chemical Industry
Fullerene‐based amino acids and peptides
Authors: Bianco Alberto , Da Ros Tatiana , Prato Maurizio , Toniolo Claudio
Published: August 2002

Recent advances in the chemistry of fullerene have allowed the synthesis of many classes of novel fullerene derivatives. Among these classes, fullerene‐based amino acids and peptides are particularly interesting, both for structural studies and biological applications. In this review, we will discuss our own achievements in this rapidly growing field. In particular, the application of fulleroproline (Fpr) amino acids and peptides to medicinal chemistry and material science will be highlighted. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Conformational flexibility of three cytoplasmic segments of the angiotensin II AT1A receptor: a circular dichroism and fluorescence spectroscopy study
Authors: Pertinhez Thelma A. , Krybus Regina , Cilli Eduardo M. , Paiva Antonio C. M. , Nakaie Clóvis R. , Franzoni Lorella , Sartor Giorgio , Spisni Alberto , Schreier Shirley
Published: August 2002

The conformation of three synthetic peptides encompassing the proximal and distal half of the third intracellular loop (Ni3 and Ci3) and a portion of the cytoplasmic tail (fCT) of the angiotensin II AT1A receptor has been studied using circular dischroism and fluorescence spectroscopies. The results show that the conformation of the peptides is modulated in various ways by the environmental conditions (pH, ionic strength and dielectric constant). Indeed, Ni3 and fCT fold into helical structures that possess distinct stability and polarity due to the diverse forces involved: mainly polar interactions in the first case and a combination of polar and hydrophobic interactions in the second. The presence of these various features also produce distinct intermolecular interactions. Ci3, instead, exists as an ensemble of partially folded states in equilibrium. Since the corresponding regions of the angiotensin II AT1A receptor are known to play an important role in the receptor function, due to their ability to undergo conformational changes, these data provide some new clues about their different conformational plasticity. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
The Eurocode for Structural loading: Eurocode 1
Authors: Gulvanessian H , Menzies J B
Published: August 2002

Eurocode 1: Actions on Structures is one of the international unified set of codes of practice known as the Structural Eurocodes, now in an advanced state of development in Europe. It provides comprehensive information and guidance on all actions (loads) that it is normally necessary to consider in the design of building and civil engineering structures. The preparation of Eurocode 1, in ten Parts, was initiated by the European Union in 1985. All Parts have been published by the European Committee for Standardization (CEN) as European pre‐standards (ENV) for voluntary use and a five‐year programme to convert them to European Standards (EN) is now at an advanced stage. This article describes the scope of Eurocode 1 and its main provisions.
Research and development in precast concrete framed structures
Authors: Elliott Kim S
Published: August 2002

Research work on precast concrete framed structures carried out over the past 20 years has culminated with the large‐scale testing of a five‐storey frame in the USA, a pan‐European project on the structural behaviour of frame connections, and the optimization of some highly engineered concrete elements. This paper reviews the most important advances, explaining to designers the relevance of the results of tests carried out on complete sway frames, on floor systems and connections subjected to gravity, horizontal and catenary forces, and on the wide‐ranging developments of elements such as prestressed hollow core floor units. The design engineer now has more information, through full‐scale experimental testing, realistic numerical studies and 3‐dimensional nonlinear computer programs, to enable safer and more efficient design than ever before.
Inhibition of the superoxide anion release and hydrogen peroxide formation in PMNLs by flavonolignans
Authors: Varga Zsuzsa , Czompa Andrea , Kakuk György , Antus Sándor
Published: August 2002

The mixture of flavonolignans [LegalonR: silybin (2a), isosilybin (3), silydianin (4) and silychristin (5)] and derivatives of silybin (2b–d) were assessed for their inhibitory activity on the oxidative burst of PMA‐stimulated human PMNLs. The inhibitory effect of flavonolignans on O2− release were compared with that of vitamin E (1). The flavonolignans tested exhibited the following order in inhibition of O2− release by PMA‐stimulated PMNLs: 5,7,4′′‐ trimethylsilybin (2c) ≈ vitamin E (1) > LegalonR ≥ peracetylsilybin (2b) > silybin (2a) > peracetyl‐5,7,4′′‐trimethylsilybin (2d). The flavonolignans inhibited not only the O2− release, but also the H2O2 formation in PMA‐stimulated PMNLs. The inhibitory capacity of flavonolignans on H2O2 formation was similar to their inhibitory capacity on O2− release. These data suggest that the flavonolignans have antioxidant properties on the PMNL oxidative burst. The fact that the trimethyl derivative of silybin (2c) has a greater inhibitory effect than silybin itself suggests that the efficacy of the antioxidant properties is dependent on the lipophilicity of the molecules. This is underlined by the fact that peracetylation of all of the hydroxyl groups in silybin resulted in a total loss of the antioxidant activity of the molecule. In summary, flavonolignans inhibit the oxidative burst of PMNLs, and this inhibitory effect depends on the chemical structure of the flavonolignans. Copyright © 2001 John Wiley & Sons, Ltd.
Manage your clinical study like an auditor
Authors: Wilkins Byard Marlene
Published: August 2002

Clinical research associates (CRAs) often panic when faced with the prospect of a site audit or inspection, and they want advice as to how to prepare for an auditor visit or inspector visit. The key to a perpetual state of readiness is to manage your clinical study as if you were an auditor. Copyright © 2002 John Wiley & Sons, Ltd.
Does quality assurance apply to development planning?
Authors: Bentzinger Claude , Schulz Miklos L , O'Brien‐Hitching Patrick
Published: August 2002

New product development planning is a complex process and the quality of the planning will have a profound effect on time to market(s) and the commercial success of a therapeutic innovation. Quality assurance has an important role in the planning process. We have drawn up a list of quality assurance criteria applicable to the planning process in R&D, clinical investigation and new business development. The list is by no means exhaustive and we welcome thoughts and comments on other criteria and other areas. Perhaps the present review will stimulate interest and raise readers' awareness of the formidable array of different considerations that must be taken into account if we are to create better therapies for tomorrow's patients. Copyright © 2002 John Wiley & Sons, Ltd.
Standard operating procedures for clinical research personnel – Part 11
Authors: Bohaychuk Wendy , Ball Graham
Published: August 2002

This is the eleventh in a series of articles containing proposals for wording and content of standard operating procedures (SOPs) for clinical research activities conducted by sponsors and Contract Research Organisations (CROs). The procedures include those required by the International Conference on Harmonisation (ICH), the Food and Drug Administration (FDA), many other guidelines and regulations, and ‘best practice’ observed by the authors. The model forms require modification for actual use. In this article, SOPs are presented for selection of CROs (SOP 326) and selection of clinical laboratories (SOP 327). (The full text of all 101 SOPs is available from the authors.) Copyright © 2002 John Wiley & Sons, Ltd.
Control charts for positively‐skewed populations with weighted standard deviations
Authors: Chang Young Soon , Bai Do Sun
Published: August 2002

This paper proposes a heuristic method of constructing $\bar{X}$, cumulative sum and exponentially weighted moving average control charts for skewed populations with weighted standard deviations obtained by decomposing the standard deviation into upper and lower deviations adjusted in accordance with the direction and degree of skewness. These control charts, however, reduce to standard control charts when the underlying distribution is symmetric. Simple formulae are derived to estimate unknown process parameters from means and ranges of subgroups. The false alarm rates of these control charts are compared with those of existing control charts when the underlying distribution is Weibull, gamma, or lognormal. Simulation results show that considerable improvement over the existing methods can be achieved when the underlying distribution is skewed. Copyright © 2001 John Wiley & Sons, Ltd.
An economic model for \font\twelveit=cmti10 scaled 1600$\overline{\kern‐0.85ex\hbox{\twelveit X}}$\nopagenumbers\end and R charts with time‐varying parameters
Authors: Ohta Hiroshi , Kimura Aritoshi , Rahim Abdur
Published: August 2002

This paper proposes an economic model for the selection of time‐varying control chart parameters for monitoring on‐line the mean and variance of a normally distributed quality characteristic. The process is subject to two independent assignable causes. One cause changes the process mean and the other changes the process variance. The occurrence times of these assignable causes are described by Weibull distributions having increasing failure rates. The paper combines two existing models: (I) the model of Ohta and Rahim (IIE Transactions 1997; 29:481–486) for a dynamic economic design of $\overline{X}$\nopagenumbers\end control charts, where a single assignable cause occurs according to a Weibull distribution and all design parameters are time varying; (II) the model of Costa and Rahim (QRE International 2000; 16:143–156) for the joint economic design of $\overline{X}$\nopagenumbers\end and R control charts where two assignable causes occur independently according to Weibull distribution, with variable sampling intervals. The advantages of the proposed model over traditional $\overline{X}$\nopagenumbers\end and R control charts with fixed parameters are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Structural stability analysis of Wigner crystal with Gaussian and Yukawa‐type positive background
Authors: Palanichamy R. Rajeswara , Iyakutti K.
Published: August 2002

Calculations of the ground‐state energies of Wigner crystals having simple cubic (sc), body‐centered cubic (bcc), face‐centered cubic (fcc), diamond, and perovskite structures and (hence) the analysis of relative stability of Wigner crystals of various different structures are reported. The positive background is represented by a periodic array of Gaussians and Yukawa‐type distribution. The effects on stability of the perturbation due to the underlying lattice have been demonstrated. Among the structures, the bcc lattice still remains the most stable known arrangement and the Yukawa‐type background leads to a lower ground state energy value compared to a Gaussian type. The calculations are done for the range of the density parameter rs corresponding to low densities for the above two cases. The range of low‐density region favorable for Wigner crystallization is found to be above rs=20. The role of correlation energy is suitably taken into account. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Ladder operators for the Morse potential
Authors: Dong Shi‐Hai , Lemus R. , Frank A.
Published: August 2002

A realization of the raising and lowering operators for the Morse potential is presented. It is shown that these operators satisfy the commutation relations for the SU(2) group. Closed analytical expressions are obtained for the matrix elements of different operators such as 1/y and d/dy. The harmonic limit of the SU(2) operators is also studied and an approach previously proposed to calculate the Franck–Condon factors is discussed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Comparative study of folate cofactor models
Authors: Kang Congmin , Feng Dacheng , Qi Chuansong , Zhao Weian , Cai Zhengting
Published: August 2002

The structures of a type of tetrahydrofolate cofactor models, asymmetric substituted imidazolinium, have been studied theoretically, and the relation of reactivities to the electronic structures of these compounds has been analyzed. It is found that the reactivity of one‐carbon unit transfer of this type of tetrahydrofolate cofactor models has a tight relation to properties of the two nitrogen atoms that link to the transferring carbon atom. The followed regularity is obtained. With the group on the para‐position of benzenesulfonyl changing from an electronic acceptor to an electronic donor, the difference between N3 and N6 is smaller step by step, and the model becomes more active to transfer one‐carbon unit gradually. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Wavepacket propagation in simple molecular systems
Authors: Burrows B. L. , Amos A. T.
Published: August 2002

A combinatorial method for solving the time‐dependent Schrödinger equation is used with the tight‐binding approximation to consider the motion of wavepackets in chains and rings. A discussion of the relationship between the uncertainty principle and our results is given. We present calculations of charge densities, currents, and transmission coefficients, which illustrate the changes in the motion due to an impurity atom in the system and the effects of an imposed field with leads connected to the molecule. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Theoretical study of reactions between MH (M=B, Al) and the H2S molecule
Authors: Chen Xian‐Yang , Zhao Cheng‐Xue , Ping Yin , Ju Guan‐Zhi
Published: August 2002

Reaction mechanisms between MH (M=B, Al) and the H2S molecule have been theoretically studied. The G3 ab initio and DFT calculations demonstrate that only one stable addition complex (HM:SH2, M=B, Al) can be formed, and that, starting from the addition complex (HM:SH2) two parallel reaction channels have been found: one is an addition reaction to give H2MSH via the three‐membered ring transition state (TS), and the other is a dehydrogenation reaction to give MSH+H2 via the four‐membered ring TS. Thermodynamics and Eyring transition state theory (TST) with the Wigner correction are also used to compute the thermodynamic functions, the equilibrium constants, A factors, and the rate constants of these reaction channels at 300–1500 K. The calculated results predict that the product H2BSH in the system of BH+H2S and the product AlSH+H2 in the system of AlH+H2S will be mainly observed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Stochastic molecular dynamics in simulations of metalloid impurities in metals
Authors: Fuks David , Dorfman Simon , Mundim Kleber C. , Ellis Donald E.
Published: August 2002

A hybrid approach is described, which combines stochastic classical molecular dynamics and first‐principles density functional theory to model the atomic structure and properties of large solid‐state systems. The stochastic molecular dynamics using generalized simulated annealing (GSA) is based on nonextensive statistical mechanics and thermodynamics. Examples of applications are given on metalloid impurities in metals. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Wigner localization and dynamics in two‐electron semiconductor rings
Authors: Puente Antonio , Serra Llorenç
Published: August 2002

We present a theoretical analysis of the electronic structure and the linear‐response dynamics for two‐dimensional rings in a perpendicular magnetic field containing two electrons. The exact lower eigenstates are found by numerically solving the Schrödinger equation and are used to build the pertubative dipole response. We show the equivalence of this technique with the integration in real time used in a previous work. Comparison with the predictions of local spin density approximation theory is also done. In narrow rings the solution is shown to correspond to a rigid rotor and thus to a localized structure in the intrinsic frame, i.e., a rotating Wigner molecule. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Shape‐dependent molecular polarizabilities
Authors: Apell S. Peter , Sabin John R. , Trickey S. B. , Oddershede J.
Published: August 2002

In a series of papers we have considered the overall effects of geometrical shape on molecular electronic properties. Molecules are mapped into ellipsoids, based on tabulated bond lengths and van der Waals radii. The main advantage of the approach is to make predictions of the influence of shape itself on important physical properties and their trends, particularly for systems which are computationally difficult or time‐consuming. The results include insight into the effect of shape on molecular stopping anisotropy, stopping in ultra‐thin films, and anisotropic Compton profiles. In this paper we extend the treatment to polarizability anisotropies and to the scaling of the polarizability of long objects in terms of the number of basic building blocks. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
The use of particle beam mass spectrometry for the measurement of impurities in a nabumetone drug substance, not easily amenable to atmospheric pressure ionisation techniques
Authors: Wolff Jean‐Claude , Hawtin Philip N. , Monté Soraya , Balogh Michael , Jones Tim
Published: August 2002

Liquid chromatography/particle beam mass spectrometry (LC/PB‐MS) was used for the structural elucidation of some impurities in nabumetone as this compound poorly ionises by atmospheric pressure ionisation (API) techniques. PB‐MS was optimised for nabumetone and a sensitivity study was carried out. To obtain full scan electron ionisation spectra a minimum of 100 ng of compound on column was needed. By using 20 mg/mL solutions of nabumetone, impurities at levels of about 250 ppm mass fraction relative to nabumetone could be detected. Results were compared with LC/API‐MS and previous GC/MS. Copyright © 2001 John Wiley & Sons, Ltd.
Genotyping short tandem repeats using flow injection and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry
Authors: Hannis James C. , Muddiman David C.
Published: August 2002

Characterizing polymerase chain reaction (PCR) amplicons has been accomplished for the first time using flow injection analysis coupled to electrospray ionization mass spectrometry (ESI‐MS). The PCR amplicons were amplified at the human tyrosine hydroxylase short tandem repeat locus from an individual homozygotic for the 9.3 allele. One product was amplified using Pfu polymerase and yielded a blunt‐ended amplicon of 82 base‐pairs (bp) in length. The second PCR product was amplified using Taq polymerase that resulted in an amplicon with cohesive termini of 82 bp plus either mono‐ or diadenylation. The two PCR amplicons were alternatively injected using a 0.5‐µL loop at 2 µM for the Pfu amplicon and 1 µM for the Taq amplicon with a flow rate of 200 nL/min during data acquisition. Both PCR amplicons were accurately identified using mass measurements illustrating the compatibility of ESI‐MS for genotyping short tandem repeat sequences and the potential for high‐throughput genotyping of large PCR amplicons. Copyright © 2001 John Wiley & Sons, Ltd.
In‐line coupling of low‐pressure short capillary electrochromatography columns to electrospray ionisation mass spectrometry
Authors: Walhagen Karin , Gaspari Marco , Tjaden Ubbo R. , Rozing Gerard P. , Greef Jan van der
Published: August 2002

A new in‐house designed and constructed injection valve for capillary electrochromatography (CEC) based on a rotating injection part with compartments for the eluent as well as for the sample has been coupled to a mass spectrometer via a sheath flow electrospray ionisation (ESI) interface, using short capillary columns of 15 cm length. The CEC columns were packed with 3 µm C18 bonded silica particles, and a mixture of peptides was analysed using an ammonium acetate/acetonitrile eluent. A significant increase in the signal‐to‐noise ratio was obtained when the peptides were dissolved in water with the same content of organic modifier as in the eluent with an addition of 0.5% (v/v) acetic acid. When the CEC analysis was performed without any additional pressure, the separation current sometimes dropped tremendously due to bubble formation, caused by different permeability in the frits and packed part of the column causing an extremely low electroosmotic flow. The separation current was restored to its original value by applying only 7 bar at the inlet of the CEC column, and the separation performance for the test peptides was recovered. A comparison of the CEC performance of peptides in pure CEC mode and in low‐pressure CEC mode is reported. Copyright© 2001 John Wiley & Sons, Ltd.
A comprehensive on‐line digestion‐liquid chromatography/mass spectrometry/collision‐induced dissociation mass spectrometry approach for the characterization of human fibrinogen
Authors: Vecchione Gennaro , Casetta Bruno , Santacroce Rosa , Margaglione Maurizio
Published: August 2002

An automatic on‐line digestion‐liquid chromatography/mass spectrometry/collision‐induced dissociation mass spectrometry (LC‐MS/CID‐MS) protocol has been developed for detection of errors in the biosynthesis of human fibrinogen, such as amino acid (AA) mismatch or incorrect post‐translational modification (PTM). Using on‐line digestion on an immobilized‐enzyme column, the reaction time is significantly reduced (less than 20 min) and the entire approach is suitable for automation. The two‐loop MS experiments (full‐scan acquisition and sugar moieties monitoring by SIM) allow checking both the correct AA mapping via the peptides generated by the digestion of the PTM. Since the protocol was designed for application on a routine basis, as a proof‐of‐concept detection of a rare case of ‘abnormal’ fibrinogen has been demonstrated. The advantage of the proposed approach is exemplified by the fact that the DNA sequence information for the case investigated had not shown any evidence of the abnormality. Copyright © 2001 John Wiley & Sons, Ltd.
Multiple‐sprayer tandem mass spectrometry with parallel high flow extraction and parallel separation for high‐throughput quantitation in biological fluids
Authors: Deng Yuzhong , Zeng Hang , Unger Steve E. , Wu Jing‐Tao
Published: August 2002

In this work, an on‐line four‐column high‐flow parallel extraction device was set up and interfaced to a four‐column parallel separation system with a four‐sprayer tandem mass spectrometric detector. This system allowed for the direct and simultaneous sampling, extraction, separation, and detection of four samples in biological fluids, resulting in significantly increased throughput. The performance of this system was evaluated using rat plasma samples spiked with methotrexate as a test compound. The results showed that the relative standard deviation for responses across the four parallel channels was less than 10% for a concentration range from 10 to 2500 nM, resulting in comparable sensitivity (slope of curve) for the analyte on all channels. A ruggedness test was performed using a mixed set of new and used extraction columns and the relative standard deviation in analyte response was found to be below 15%. The inter‐channel crosstalk was measured to be about 0.1%. A comparison between the data generated on this system and on a conventional system for a rat pharmacokinetic study showed no more than 20% difference in measured concentrations. This parallel system is a viable tool for high‐throughput bioanalysis in a drug discovery environment. Copyright © 2001 John Wiley & Sons, Ltd.
Study of the mass spectrometric behaviour of phthalocyanine and azo dyes using electrospray ionisation and matrix‐assisted laser desorption/ionisation
Authors: Conneely A. , McClean S. , Smyth W. F. , McMullan G.
Published: August 2002

The negative ion MALDI‐MS and ESI‐MS behaviour of sulphonated copper phthalocyanine dyes has shown the presence of both anionic and radical anionic species. Substituent groups such as sulphonates and linker arms, as are present in commercial dyes such as Remazol TB and Everzol TB, are found to be labile and the dyes undergo in‐source fragmentation in both MALDI‐MS and ESI‐MS. Ions corresponding to sodium salts can be formed. It appears that Cu is firmly bound in the phthalocyanine structure, unlike the corresponding Mg and Al chelates that can undergo demetallation. The application of ESI‐MSn confirmed that these labile groups can be fragmented from the dye molecules and, in addition, SO2 losses are observed as for EI‐MS. Hydrolysed commercial azo dyes such as Remazol Black B (I) and Remazol Red RB (III) showed both singly and doubly charged molecular anion species as well as sodium salts using negative ion ESI‐MS, but did not desulphonate like the copper phthalocyanine dyes. The application of ESI‐MSn revealed fragmentation of the dye molecules with the loss of entities such as HOCH2CH2SO2C6H4N2 (for both dyes) and SO2 (for Remazol Black B). MALDI‐MS, ESI‐MS and ESI‐MSn can therefore be used for the characterisation of such dyes by exploiting these fragmentation processes, and some structural information can be obtained for the dyes whose structures are not in the public domain. Copyright© 2001 John Wiley & Sons, Ltd.
Negative ion electrospray mass spectra of caerulein peptides: an aid to structural determination
Authors: Boontheung Pinmanee , Alewood Paul F. , Brinkworth Craig S. , Bowie John H. , Wabnitz Paul A. , Tyler Michael J.
Published: August 2002

MS/MS data derived from the [M − H]− ions of desulfated caerulein peptides provide (i) sequencing information from a combination of α, β and γ backbone cleavages, and (ii) identification of specific amino acid side chains by side‐chain cleavages [e.g. Ser (−CH2O), Thr (−CH3CHO) and Asp (−H2O)] (fragmentations having no counterparts in positive ion spectra). In addition, δ and/or γ backbone cleavage ions from Asp residues identify the position of these residues in the peptide. In contrast, neither δ nor γ cleavage ions are observed from either the Gln2 residue nor from Phe residues. Full structural information can be obtained from a consideration of the positive and negative ion MS/MS data in concert. Copyright © 2002 John Wiley & Sons, Ltd.
Rotating ball inlet mass spectrometry enhanced by electrochemical effects
Authors: Degn Hans , Christensen Torben , Sørensen René
Published: August 2002

The sample compartment in a rotating ball inlet mass spectrometer is made into an electrochemical cell where the rotating platinum ball can be electrically polarised relative to the sample liquid. Positive polarisation of the ball increases the mass peak intensities of weak acids and reduces those of weak bases. Negative polarisation of the ball reduces the mass peak intensities of weak acids and increases those of weak bases. These effects are caused by local changes in pH at the ball surface due to the electrolysis of water. When aliphatic alcohols are present in the sample solution positive polarisation of the ball results in the appearance of peaks due to electrochemical oxidation products of these alcohols. The effects of electric polarisation of the ball are potentially useful in the identification of analytes. Rotating ball inlet mass spectrometry with electric polarisation of the ball offers an alternative to conventional differential electrochemical mass spectrometry (DEMS). Copyright © 2002 John Wiley & Sons, Ltd.
Backbone cleavages of [M − H]− anions of peptides. Cyclisation of citropin 1 peptides involving reactions between the C‐terminal [CONH]− residue and backbone amide carbonyl groups. A new type of β cleavage: a joint experimental and theoretical study
Authors: Brinkworth Craig S. , Dua Suresh , Bowie John H.
Published: August 2002

This paper reports the study of backbone cleavages in the collision‐induced negative‐ion mass spectra of the [M − H]− anions of some synthetic modifications of the bioactive amphibian peptide citropin 1 (GLFDVIKKVASVIGGL‐NH2). The peptides chosen for study contain no amino acid residues which could effect facile side‐chain cleavage, i.e. Ser (−CH2O, side‐chain cleavage) and Asp (−H2O) are replaced by Ala or Lys. We expected that such peptides should exhibit standard and pronounced peaks due to α cleavage ions (and to a lesser extent β cleavage ions) in their collision‐induced negative‐ion spectra. This expectation was realised, but the spectra also contained peaks formed by a new series of cleavage anions. These are produced following cyclisation of the C‐terminal CONH− moiety at carbonyl functions of amide groups along the peptide backbone; effectively transferring the NH of the C‐terminal CONH− group to other amino acid residues. We have called the product anions of these processes β′ ions, in order to distinguish them from standard β ions. Some β′ ions also fragment directly to some other β′ ions of smaller mass. The reaction coordinates of α,β and β′ backbone processes have been calculated at the HF/6‐31G*//AM1 level theory for simple model systems. The initial cyclisation step of the β′ sequence is barrierless and exothermic. Subsequent steps have a maximum barrier of +40 kcal mol−1, with the overall reaction being endothermic by some 30 kcal mol−1 at the level of theory used. These calculations take no account of the complexity of the conformationally flexible peptide system, and it is surprising that each of the two reacting centres can ‘find’ each other in such a large system. Copyright © 2002 John Wiley & Sons, Ltd.
Using a high‐resolution magnetic sector mass spectrometer for fast analysis of transient reaction processes in automotive catalytic converters
Authors: Harmsen J. M. A. , Bijvoets Th. , Hoebink J. H. B. J. , Hachiya T. , Bassett J. , Brooker A. D. , Schouten J. C.
Published: August 2002

A high‐resolution magnetic sector mass spectrometer has been developed and used for transient kinetic measurements on reactions that are important for automotive exhaust gas catalysis. This instrument allows separation of the isobaric masses of CO and N2 as well as CO2 and N2O, which are separately monitored in time at a sampling rate of 48 Hz. The time resolution is sufficient to determine individual kinetic rate parameters for reactions under transient conditions. A description of the experimental set‐up as well as the software used is given. The results are illustrated by the catalytic reduction of NO by CO. To the best knowledge of the authors, this is the first application of a magnetic sector mass spectrometer for kinetic research under dynamic operation conditions. Copyright © 2002 John Wiley & Sons, Ltd.
A Case Study of the Beneficial Reuse of Treated Groundwater
Authors: Elmore Andrew Curtis , Graff Thomas
Published: August 2002

The future disposal of treated groundwater at the former Nebraska Ordnance Plant (NOP) Superfund
site has been a topic of interest to the local property owners, the U.S. Army Corps of Engineers, and the local
regulatory agencies. The Record of Decision for the site includes the extraction, treatment, and disposal of
almost 3,000 gpm of groundwater with an estimated restoration time period exceeding 100 years. Interest from
property owners and the Nebraska agency charged with regulating groundwater supply prompted the Corps of
Engineers to consider several strategies for beneficially reusing the treated water. Alternatives included the
establishment of a rural water district or local distribution system; delivery of the water to the municipal
supply system of Lincoln, Nebraska, andsol;or other nearby municipalities; and consideration of innovative
remedial technologies to reduce the quantity of treated water requiring disposal. The selected disposal plan
consists of providing treated groundwater to interested parties for agricultural use with excess treated
groundwater discharged to two streams. Multiple feasibility studies were generated, public input was solicited,
and interagency agreements were executed during the course of the project. The remediation project is currently
being constructed, and at least one property owner has constructed a new center‐pivot irrigation system
to use the treated groundwater. © 2001 John Wiley & Sons.