bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discovery of potent and selective peptide agonists at the GRP‐preferring bombesin receptor (BB2)
Authors: Darker John G. , Brough Stephen J. , Heath Jennie , Smart Darren 
Published: August 2002

AbstractAnalogues of the nonselective bombesin receptor synthetic agonist H‐D‐Phe‐Gln‐Trp‐Ala‐Val‐βAla‐His‐Phe‐Nle‐NH2 were prepared and their biological activity assessed at the NMB‐preferring/bombesin receptor (NMB‐R; BB1), the GRP‐preferring/bombesin receptor (GRP‐R; BB2) and the orphan receptor bombesin receptor subtype‐3 (BRS‐3; BB3). Progressive N‐terminal deletions identified the minimum C‐terminal sequences required for maintaining a significant agonist effect, whilst an alanine scan, targeted changes in stereochemistry and other pertinent substitutions identified key side‐chain and stereochemical requirements for activation. Key structural elements required for functional potency at BB1 BB2 and BB3, and for selectivity between these receptor subtypes were established. Synthetic peptides were discovered, which were highly potent agonists at BB2 and extremely selective over both BB1 and BB3. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.
Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method
Authors: Mensor Luciana L. , Menezes Fábio S. , Leitão Gilda G. , Reis Alexandre S. , Santos Tereza C. dos , Coube Cintia S. , Leitão Suzana G. 
Published: August 2002

AbstractBrazilian plant extracts belonging to 16 species of 5 different families (71 extracts) were tested against the stable DPPH (2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate) free‐radical. The ability to scavenge DPPH radical was measured in these experiments by the discoloration of the solution. Ginkgo biloba and rutin, commonly used as antioxidants for medical purposes, were used as standards. Based on our results, we can say that as a general rule the ethanol extracts of plants belonging to the Verbenaceae family showed lower EC50 values than the other plant extracts. Among the partitions, the more polar ones (ethyl acetate and n‐butanol) are those that generally have higher antioxidant activity (AA). Copyright © 2001 John Wiley & Sons, Ltd.
The antioxidant activity of the essential oils of Artemisia afra, Artemisia abyssinica and Juniperus procera
Authors: Burits M. , Asres K. , Bucar F. 
Published: August 2002

AbstractThe essential oils of Artemisia afra Jacq., Artemisia abyssinica Schultz‐Bip. and Juniperus procera Hoechst ex Endl. were examined for their potential radical scavenging activities. First a rapid evaluation of antioxidants was made using a TLC screening method. The abilities of the volatile oils to act as nonspecific donors for hydrogen atoms or electrons were checked in the diphenylpicrylhydrazyl assay. Oils from all three species showed positive results and were examined further. The oils of A. afra and J. procera were also effective hydroxyl radical scavenging agents when assessed in the deoxyribose degradation assay, whilst oils from A. abyssinica exhibited a paradoxical effect. In the in vitro assay for non‐enzymatic lipid peroxidation in liposomes, the oils of A. afra and J. procera also displayed antioxidant potential. It was not possible to measure the effect of A. abyssinica oil in this system because certain components, e.g. alk‐2‐enals, interfered with the assay. The compounds that contribute to the radical scavenging activities of A. afra and J. procera were identified and then assessed for their effects in the various test systems. Finally, the qualitative and quantitative compositions of the essential oils were studied by GC‐MS. Copyright © 2001 John Wiley & Sons, Ltd.
Experience with St John's Wort (Hypericum perforatum) in children under 12 years with symptoms of depression and psychovegetative disturbances
Authors: Hübner Wolf‐Dietrich , Kirste Tilman 
Published: August 2002

AbstractThe value of an extract of Hypericum perforatum (St John's wort) for children with mild to moderate depressive symptoms was investigated for the first time in a multi‐centre post‐marketing surveillance study. One hundred and one children under 12 years were treated for a minimum of 4 weeks with an extension to 6 weeks with parental consent and medical practitioner recommendation. the dosage used ranged from 300 to 1800 mg per day. Compliance, tolerability and efficacy were assessed every 2 weeks by physicians and parents. Based on the data available for analysis, the number of physicians rating effectiveness as ‘good’ or ‘excellent’ was 72% after 2 weeks, 97% after 4 weeks and 100% after 6 weeks. The ratings by parents were very similar. There was, however, an increasing amount of missing data at each assessment point with the final evaluation including only 76% of the initial sample. Tolerability was good and no adverse events were reported. The results of this study suggest that Hypericum is a potentially safe and effective treatment for children with symptoms of depression. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of Cirsium pascuarense on blood glucose levels of normoglycaemic and alloxan‐diabetic mice
Authors: Perez G. R. M. , Ramirez L. M. E. , Vargas S. R. 
Published: August 2002

AbstractBlood glucose levels of normal and alloxan‐treated diabetic mice were determined after i.p. administration of various doses of the hexane, chloroform and methanol extracts of Cirsium pascuarense. From the data obtained, it is concluded that the i.p. administration of 100, 150 and 200 mg/kg of hexane extract of this plant produced a significant hypoglycaemic effect in normal as well as in diabetic mice. In addition, the extracts altered glucose tolerance in alloxan induced diabetic rats. Chloroform and methanol extracts did not produce any significant change in blood glucose levels. Copyright © 2001 John Wiley & Sons, Ltd.
Information distance analysis of molecular electron densities
Authors: Nalewajski Roman F. , Świtka Elžbieta , Michalak Artur 
Published: August 2002

AbstractThe information‐theoretic basis of the Hirshfeld partitioning of the molecular electronic density into the densities of the “stockholder” atoms‐in‐molecules (AIM) is summarized. It is argued that these AIM densities minimize both the directed divergence (Kullback–Leibler) and divergence (Kullback) measures of the entropy deficiency between the AIM and their free atom analogs of the promolecule. The local equalization of the information distance densities of the Hirshfeld components, at the local value of the corresponding global entropy deficiency density, is outlined and several approximate relations are established between the alternative local measures of the missing information and the familiar function of a difference between the molecular and promolecule densities. Various global (of the system as a whole) and atomic measures of the entropy deficiency or the displacements relative to the isoelectronic promolecule, defined for densities or probabilities (shape functions) in both the local resolution and the Hirshfeld AIM discretization, are introduced and tested. This analysis is performed also for the valence electron (frozen‐core) approximation. Illustrative results for representative linear molecules, including diatomics, triatomics, and tetraatomics, are reported. They are interpreted as complementary characteristics of changes in the net AIM charge distribution and of the displacements in the information content of the electron distributions of bonded atoms. These numerical results confirm the overall similarity of the stockholder AIM to their free atom analogs and reflect the information displacements due to the AIM polarization and charge transfer in molecules. They also demonstrate the semiquantitative nature of the approximate relations established between the entropy deficiency densities and the related functions involving the density difference function. This development extends the range of interpretations based on the density difference diagrams into probing the associated information displacements in a molecule accompanying the formation of the chemical bonds. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Radical polymerization of diallylamine compounds: From quantum chemical modeling to controllable synthesis of high‐molecular‐weight polymers
Authors: Timofeeva L. M. , Vasilieva Y. A. , Kleshcheva N. A. , Gromova G. L. , Topchiev D. A. 
Published: August 2002

AbstractWe investigated the possibility to obtain high‐molecular‐weight (HMW) polymers from the monomers of the diallylamine (DAA) series using quantum chemical and experimental methods. Such monomers are known to polymerize into oligomeric products due to the reaction of the degradative chain transfer to the monomer. We studied potential energy profiles of the chain propagation and competing chain transfer reactions, viz., the free radical double bond addition and α‐hydrogen radical abstraction, respectively, for a number of polymerization processes. Calculations were carried in the framework of the polarized continuum solvent model utilizing the procedure based on the semiempirical MNDO‐PM3 background. It was found that the necessary condition for decreasing competitiveness of the chain transfer to the monomer is the availability of monomer molecules in only protonated form in the polymerizing system. Using these results, we developed the strategy for obtaining HMW polymers based on said monomers. We synthesized a monomer system (the equimolar salt of N,N‐diallyl‐N‐methylamine and trifluoroacetic acid) that fully corresponds to such requirements. Novel HMW polymers were then synthesized by radical polymerization of this salt at soft conditions. We established that chain termination is controlled by the bimolecular mechanism. We showed that the degradative chain transfer transforms into the effective chain transfer. The mechanisms of the observed phenomena are discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Possibilities of molecular magnetic metals and high Tc superconductors in field effect transistor configurations
Authors: Kawakami Takashi , Kitagawa Yasutaka , Matsuoka Fumitake , Yamashita Yoshifumi , Isobe Hiroshi , Nagao Hidemi , Yamaguchi Kizashi 
Published: August 2002

AbstractAb initio molecular orbital (MO) and density functional theory (DFT) calculations of neutral and anion radical states of anthracene are performed to elucidate their vibrational frequencies. They are used to calculate the transition temperatures of superconductivity of these species in the field effect transistor (FET) configuration on the basis of the electron–phonon coupling mechanism. Anderson and Kondo lattice models are also examined in relation to possible electronic phases of segregated columns of donors or acceptors with radical groups, and conducting polymers with radical groups in the FET configuration. The effective exchange interactions within conduction electrons and localized spins are calculated by theoretical methods. The electron or hole doping into molecular crystals and/or thin films of these systems in the FET configuration are studied in relation to possible magnetic states, Kondo and dense Kondo states, and superconducting states via spin fluctuations. The cooperative mechanism between the electron–phonon and spin fluctuation is also discussed to search the high Tc superconductor. Finally, the magnetic modifications of helical conducting polymers and DNA chains with chiral spin sources are discussed in relation to possibility of molecular solenoid, which may be generated in the FET configuration. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Solving the hydrodynamic formulation of quantum mechanics: A parallel MLS method
Authors: Brook R. Glenn , Oppenheimer Paul E. , Weatherford Charles A. , Banicescu Ioana , Zhu Jianping 
Published: August 2002

AbstractThis article documents the first implementation of a parallel algorithm for solving the governing equations of the hydrodynamic formulation of quantum mechanics. The algorithm employs a quantum trajectory method (QTM) based on the serial algorithm introduced by Wyatt and Lopreore. The OpenMP API is employed to parallelize the code across the quantum trajectories in a shared memory environment. An outline of the parallel algorithm is provided; the analytical solution for a moving free particle is used to verify the solution obtained by the parallel algorithm. Further validation against several of the results obtained by Wyatt and Lopreore is also provided. The parallel speedups and runtimes are presented, and several performance issues are noted. Finally, the results of a preliminary accuracy study examining a moving free particle are provided. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Role of initial orbital alignment in H++K(4p) collisions at low energies
Authors: Saha Bidhan C. , Kumar Anil 
Published: August 2002

AbstractWe report calculations of state‐selective electron capture by H+ from K(4p) in Σ and Π alignments, in the 0.01–1 keV/amu energy range. We use, in the impact parameter formalism, the semiclassical close‐coupling method with molecular‐state expansion embodying electronic translation factors. Molecular states and adiabatic states are obtained from standard one‐electron LCAO calculations using Slater‐type orbitals and pseudopotentials for the e−–K core interactions. In addition to the state‐selective capture cross sections, we also have calculated the K(5s), K(3d), and K(5p) excitation cross sections. We report the anisotropy parameters A(n) for n=2 and n=3 states of the formed H atom as well as A(ex) for populating the excited states of the K atom for the first time. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Evaluating the relative free energy of hydration of new thrombin inhibitor candidates using the finite difference thermodynamic integration (FDTI) method
Authors: Guimarães Cristiano Ruch Werneck , Bicca de Alencastro Ricardo 
Published: August 2002

AbstractThrombin is a serine protease involved in blood coagulation. Since thrombin inhibitors appear to be effective in the treatment and prevention of thrombotic and embolic disorders, considerable attention has been focused on the structure and interactions of the enzyme. In this work, we calculated the relative free energies of hydration of the new thrombin inhibitor candidates, p‐substituted derivatives of benzamidine, a well‐known noncovalent thrombin inhibitor. We used molecular dynamics and the finite difference thermodynamic integration (FDTI) algorithm within the Discover program of MSI. We have shown that the orthogonality problem that occurs in the calculation of intraperturbed‐group contributions to the free energy is treated adequately by the FDTI method. We have also shown that problems of singularity and convergence in free energy calculations can be properly solved using this method. To conclude, the calculated free energies of hydration gave the following order of solvation for the candidates: p‐(2‐oxo‐1‐propyl)benzamidine > p‐methylbenzamidine > p‐ethylbenzamidine > p‐(1‐propyl)benzamidine > benzamidine. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Identification of proteins from Escherichia coli using two‐dimensional semi‐preparative electrophoresis and mass spectrometry
Authors: Gustafsson Elisabet , Thorén Kajsa , Larsson Thomas , Davidsson Pia , Karlsson Karl‐Anders , Nilsson Carol L. 
Published: August 2002

AbstractEscherichia coli is a gram‐negative bacterium that causes sepsis and infections of the nervous system, and the digestive and urinary tracts. The availability of the complete nucleotide sequence encoding the E. coli K‐12 genome has made this organism an excellent model for proteomic studies. Semi‐preparative two‐dimensional electrophoresis, including liquid phase isoelectric focusing (IEF), one‐dimensional sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and gel elution, have for the first time been used in combination with matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS), electrospray tandem mass spectrometry and database searching for rapid separation of proteins from a uropathogenic strain of E. coli. The identity of 30 proteins, including the membrane protein nmpC, was obtained using this approach. Copyright © 2001 John Wiley & Sons, Ltd.
Melanogenesis by tyrosinase action on 3,4‐dihydroxyphenylalanine (DOPA) in the presence of polyethylene glycol: a matrix‐assisted laser desorption/ionization mass spectrometric investigation
Authors: Bertazzo Antonella , Vogliardi Susanna , Favretto Donata , Costa Carlo V. L. , Allegri Graziella , Traldi Pietro 
Published: August 2002

AbstractThe enzymatic reaction between DOPA and tyrosinase, the enzyme considered to be responsible for melanogenesis, was carried out in the presence of polyethylene glycol (PEG). This choice was made in order to increase the solubility of melanins, since these polymers are highly insoluble. The reaction mixtures were sampled at different times, immediately ultrafiltered to remove the enzyme, lyophilized, and analyzed by matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. The results were very different from those obtained in the absence of PEG. Only a few oligomers of dihydroxyindole (DHI) and dihydroxyindole‐2‐carboxylic acid (DHICA) were detected in low abundances, whereas new species originating from reaction of PEG with species belonging to the Raper‐Mason pattern appeared. The results show that, in the presence of PEG, tyrosinase‐catalyzed oligomerization of DOPA exhibits kinetics slower than those observed in the absence of the polymer. However, melanogenesis still takes place in the presence of PEG, as indicated by the formation of black pigments and by the detection of DHI and DHICA oligomers, considered to be the first intermediates in melanin formation. Copyright © 2001 John Wiley & Sons, Ltd.
Improvement of in‐gel digestion protocol for peptide mass fingerprinting by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Katayama Hiroyuki , Nagasu Takeshi , Oda Yoshiya 
Published: August 2002

AbstractHigh‐sensitivity, high‐throughput analysis of proteins for proteomics studies is usually performed by polyacrylamide gel electrophoresis in combination with mass spectrometry. However, the quality of the data obtained depends on the in‐gel digestion procedure employed. This work describes an improvement in the in‐gel digestion efficiency for matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) analysis. A dramatic improvement in the coverage of tryptic peptides was observed when n‐octyl glucoside was added to the buffer. Whole cell extracted proteins from S. cerevisiae were separated by two‐dimensional gel electrophoresis and stained with silver. Protein spots were identified using our improved in‐gel digestion method and MALDI‐TOFMS. In addition, the mass spectra obtained by using the matrix α‐cyano‐4‐hydroxycinnamic acid (CHCA) were compared with those obtained using 2,5‐dihydroxybenzoic acid (DHB). The DHB matrix usually gave more peaks, which led to higher sequence coverage and, consequently, to higher confidence in protein identification. This improved in‐gel digestion protocol is simple and useful for protein identification by MALDI‐TOFMS. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of a novel series of alkylitaconic acids in wood cultures of Ceriporiopsis subvermispora by gas chromatography/mass spectrometry
Authors: del Río José C. , Gutiérrez Ana , Martínez María J. , Martínez Ángel T. 
Published: August 2002

AbstractA novel series of long‐chain unsaturated dicarboxylic acids consisting of a long aliphatic chain attached to the C‐3 position of itaconic acid has been identified by gas chromatography/mass spectrometry during in vitro decay of eucalypt wood by the white‐rot basidiomycete Ceriporiopsis subvermispora. The major compounds were identified as tetradecyl‐, 7‐hexadecenyl‐ and hexadecylitaconic acids by their mass fragmentation patterns. Other members of the same compound series, identified as dodecanyl‐, tridecanyl‐, tetradecenyl‐, pentadecanyl‐, octadecenyl‐ and octadecanylitaconic acids, were present in very minor amounts or traces. Whereas hexadecenylitaconic acid has already been reported in cultures of C. subvermispora, to our knowledge this is the first report of the presence of the other alkylitaconic acids in fungal cultures. These new alkylitaconic‐type metabolites may constitute a source for peroxidizable lipids involved in lignin degradation during wood decay by C. subvermispora and other white‐rot basidiomycetes. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of the interface of a large protein–protein complex using H/D exchange and Fourier transform ion cyclotron resonance mass spectrometry
Authors: Yamada Naoyuki , Suzuki Ei‐ichiro , Hirayama Kazuo 
Published: August 2002

AbstractAn infrared multiphoton dissociation (IRMPD) spectrum, obtained by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), was used to dissociate and to identify fragment ions from recombinant human interleukin‐6 (IL‐6; 21 KDa). The entire sequence was assigned by a single IRMPD experiment, and the observed fragment ions reflected the IL‐6 secondary structure. This method was combined with H/D off‐exchange to identify IL‐6 and anti‐human IL‐6 mouse monoclonal antibody MH166 (150 kDa) binding sites in the IL‐6 molecule. To facilitate the data analysis, the protein complex formation and the hydrogen exchange were performed with an immobilized antibody. Quenching of the hydrogen exchange reaction and collection of the deuterated IL‐6 were performed by elution under acidic conditions to measure the mass spectrum directly. IL‐6 was dissociated by using IRMPD, and the interface of IL‐6 bound to anti‐IL‐6 antibody MH166 was determined to analyze the deuterium incorporation level of each fragment ion. Thus, two discontinuous regions, Leu 126‐Lys 131 and Asp 160‐Met 184, were identified as the antibody binding sites. These regions are adjacent to each other on the tertiary structures determined by NMR and X‐ray analyses. Copyright © 2002 John Wiley & Sons, Ltd.
Electrospray ionization tandem mass spectrometric characteristics and fragmentation mechanisms of distamycin analogues
Authors: Tang Feili , Wang Jin , Liu Dan , Yuan Gu , Liu Yen , Jin Zhu Chang , Fen Zhao Yu 
Published: August 2002

AbstractThe electrospray ionization tandem mass spectrometric (ESI‐MS/MS) characteristics and fragmentation mechanisms of eight distamycin analogues containing N‐methylpyrrole and N‐methylimidazole were investigated. The members of two isomeric groups of distamycin analogues with the same elemental composition can be distinguished by MS/MS spectra of protonated molecules and of significant fragment ions. Copyright © 2002 John Wiley & Sons, Ltd.
Controlled Lagrangians and the stabilization of Euler–Poincaré mechanical systems
Authors: Bloch Anthony M. , Leonard Naomi Ehrich , Marsden Jerrold E. 
Published: August 2002

AbstractIn this paper we develop a constructive approach to the determination of stabilizing control laws for a class of Lagrangian mechanical systems with symmetry — systems whose underlying dynamics are governed by the Euler–Poincaré equations. This work extends our previous work on the stabilization of mechanical control systems using the method of controlled Lagrangians. The guiding principle behind our methodology is to develop a class of stabilizing feedback control laws which yield closed‐loop dynamics that remain in Lagrangian form. Using the methodology for Euler–Poincaré systems, we analyse stabilization of a satellite and an underwater vehicle controlled with momentum wheels. Copyright © 2001 John Wiley & Sons, Ltd.