bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking Chemical Kinetics in High‐Throughput Systems
Authors: Boelens Hans F. M. , Iron David , Westerhuis Johan A. , Rothenberg Gadi
Published: August 2003

Combinatorial chemistry and high‐throughput experimentation (HTE) have revolutionized the pharmaceutical industry—but can chemists truly repeat this success in the fields of catalysis and materials science? We propose to bridge the traditional “discovery” and “optimization” stages in HTE by enabling parallel kinetic analysis of an array of chemical reactions. We present here the theoretical basis to extract concentration profiles from reaction arrays and derive the optimal criteria to follow (pseudo)first‐order reactions in time in parallel systems. We use the information vectorfand introduce in this context theinformation gain ratio,χr, to quantify the amount of useful information that can be obtained by measuring the extent of a specified reactionrin the array at any given time. Our method is general and independent of the analysis technique, but it is more effective if the analysis is performed on‐line. The feasibility of this new approach is demonstrated in the fast kinetic analysis of the carbon–sulfur coupling between 3‐chlorophenylhydrazonopropane dinitrile andβ‐mercaptoethanol. The theory agrees well with the results obtained from 31 repeated CS coupling experiments.
Preparative and Electrochemical Investigations on the Electron Sponge Behavior of Cobalt Telluride Clusters: CO Substitution in [Co11Te7(CO)10]n− Ions (n=1, 2) by PMe2Ph and Crystal Structure of [Co11Te7(CO)5(PMe2Ph)5]
Authors: Brunner Henri , Cattey Hélène , Meier Walter , Mugnier Yves , Stückl A. Claudia , Wachter Joachim , Wanninger Robert , Zabel Manfred
Published: August 2003

The reaction of the cluster salts [Cp${^{{\ast}}_{2}}$Nb(CO)2]n[Co11Te7(CO)10] (Cp*=C5Me5; n=1, 2) with excess PMe2Ph gave the neutral, dark brown clusters [Co11Te7(CO)6(PMe2Ph)4] (5) and [Co11Te7(CO)5(PMe2Ph)5] (6) with 147 metal valence electrons. The new compounds were characterized by IR spectroscopy, elemental analyses, and mass spectrometry. The molecular structure of 6 was determined by X‐ray crystallography. Like its precursor anion, it consists of a pentagonal‐prismatic [Co11Te7] core, but with a ligand sphere composed of five CO and five PMe2Ph ligands. Detailed electrochemical studies of both reactions reveal that a stepwise substitution of CO ligands in the initial cluster anions takes place leading to intermediate [Co11Te7(CO)10−m(PMe2Ph)m]n− ions (m=1–5; n=1, 2). Each of these intermediates is distinguished by at least one oxidation and two reduction waves, giving rise to a total of 21 redox couples and 27 electroactive species. The electron sponge character of the new compounds is particularly pronounced in 5, which exhibits charges n between +1 and −4 corresponding to metal valence electron counts of between 146 and 151.
Galactose Oxidase Models: Tuning the Properties of CuII–Phenoxyl Radicals
Authors: Philibert Aurélie , Thomas Fabrice , Philouze Christian , Hamman Sylvain , Saint‐Aman Eric , Pierre Jean‐Louis
Published: August 2003

Four tripodal ligands with an N3O coordination sphere were synthesized: (2‐hydroxy‐3‐tert‐butyl‐5‐nitrobenzyl)bis(2‐pyridylmethyl)amine (LNO2H), (2‐hydroxy‐3‐tert‐butyl‐5‐ fluorobenzyl)bis(2‐pyridylmethyl)amine (LFH), (2‐hydroxy‐3,5‐di‐tert‐butylbenzyl)bis(2‐pyridylmethyl)amine (LtBuH) and (2‐hydroxy‐3‐tert‐butyl‐5‐methoxybenzyl)bis(2‐pyridylmethyl)amine (LOMeH). Their square‐pyramidal copper(II) complexes, in which the phenol subunit occupies an axial position, were prepared and characterized by X‐ray crystallography and UV/Vis and EPR spectroscopy. The phenolate moieties of the copper(II) complexes of LtBuH and LOMeH were electrochemically oxidized to phenoxyl radicals. These complexes are EPR‐active (S=1), highly stable (kdecay=0.008 min−1 for [CuII(LOMe.)(CH3CN)]2+) and stoichiometrically oxidise benzyl alcohol. Two additional tripodal ligands providing an N2O2 coordination sphere were also studied: (2‐pyridylmethyl)(2‐hydroxy‐3‐tert‐butyl‐5‐methoxybenzyl)(2‐hydroxy‐3‐tert‐butyl‐5‐nitrobenzyl)amine (L′OMeNO2H2) and (2‐pyridylmethyl)bis(2‐hydroxy‐3‐tert‐butyl‐5‐ methoxy)benzylamine (L′OMe2H2). Their copper(II) complexes were isolated as dimers ([Cu${^{{\rm II}}_{2}}$(L′OMe2)2], [Cu${^{{\rm II}}_{2}}$(L′OMeNO2)2]) that are converted to monomers on addition of pyridine. The complexes were investigated by X‐ray crystallography and UV/Vis and EPR spectroscopy. Their one‐electron electrochemical oxidation leads to copper(II)–phenoxyl systems that are less stable than those of the N3O complexes. The N2O2 complexes are more reactive than the N3O analogues: they aerobically oxidize benzyl alcohol to benzaldehyde at a higher rate, as well as ethanol to acetaldehyde (40–80 turnovers).
Supramolecular [6]Chochin and “Big Mac” Made from Chiral Piedfort Assemblies
Authors: Czugler Mátyás , Weber Edwin , Párkányi László , Korkas Petros P. , Bombicz Petra
Published: August 2003

Facile chemical synthesis of the natural chiral‐pool‐derived host 1 and its subsequent crystallization (“supramolecular synthesis”) from different solvents yielded crystalline assemblies. Crystal structure determinations of five of the so formed solvent‐inclusion compounds (1 a–1 e) reveal hexagonal symmetries in four cases. The structural characteristics of these chiral host–guest ensembles with varying stoichiometries can be best described as assemblies formed through intra‐pair hydrogen bridges of host molecules into Piedfort pairs of differing complexity. Hitherto undescribed, these Piedfort pairs also form even larger regular assemblies that we designate “Big Mac”‐like shapes. In the only nonhexagonal case, six independent host molecules form a huge supramolecular analogue of [6]benzocyclophane, also known as [6]chochin, extending this giant supermolecule through intermolecular hydrogen bonds into macroscopic (mm‐size) dimensions. As all these crystals are inherently chiral, and new model systems for solid‐state applications can be envisaged.
Chemistry of Bridging Phosphanes: PdI Dimers Bearing 2,5‐Dipyridylphosphole Ligands
Authors: Leca François , Sauthier Mathieu , Deborde Valérie , Toupet Loïc , Réau Régis
Published: August 2003

Two synthetic routes to PdI dimers that feature a bridging 1‐phenyl‐ and 1‐cyclohexyl‐2,5‐di(2‐pyridyl)phosphole ligand, 3 a and 3 b, respectively, are described. The first involves a conproportionation process between PdII and Pd0 complexes, while the second involves ligand displacement from a preformed PdI dimer. Both routes are operable for 1‐phenylphosphole 1 a, whereas the former failed with 1‐cyclohexylphosphole 1 b. A mechanistic study revealed that the conproportionation pathway implies a reversible oxidative addition of the PC(phenyl) bond of PdII‐coordinated 1 a to Pd0 leading to a bimetallic PdII complex 5. The structures of complexes 3 a and 3 b were studied by means of X‐ray diffraction. The similarity of these solid‐state structures suggests that the bridging mode of the P atom is due to μ‐1κN:1,2κP:2κN coordination of ligands 1 a, b. The electrochemical behaviour and UV/Vis absorption properties of complexes 3 a, b are reported. Complex 3 a is inert towards CO, PPh3 and 1,3‐dipoles. It reacted with dimethylacetylene dicarboxylate to give complex 6 as a result of insertion of the alkyne into the PdPd bond. X‐ray diffraction studies of complexes 5 and 6 are also presented.
Ab Initio Study on the Mechanism of the Atmospheric Reaction OH+O3→HO2+O2
Authors: Peiró‐García Julio , Nebot‐Gil Ignacio
Published: August 2003

The atmospheric reaction (1) OH + O3→HO2 + O2 was investigated theoretically by using MP2, QCISD, QCISD(T), and CCSD(T) methods with various basis sets. At the highest level of theory, namely, QCISD, the reaction is direct, with only one transition state between reactants and products. However, at the MP2 level, the reaction proceeds through a two‐step mechanism and shows two transition states, TS1 and TS2, separated by an intermediate, Int. The different methodologies employed in this paper consistently predict the barrier height of reaction (1) to be within the range 2.16–5.11 kcal mol−1, somewhat higher than the experimental value of 2.0 kcal mol−1.
Evaluation of one‐ and two‐equation low‐Re turbulence models. Part I—Axisymmetric separating and swirling flows
Authors: Yaras M. I. , Grosvenor A. D.
Published: August 2003

This first segment of the two‐part paper systematically examines several turbulence models in the context of three flows, namely a simple flat‐plate turbulent boundary layer, an axisymmetric separating flow, and a swirling flow. The test cases are chosen on the basis of availability of high‐quality and detailed experimental data. The tested turbulence models are integrated to solid surfaces and consist of: Rodi's two‐layer k–ε model, Chien's low‐Reynolds number k–ε model, Wilcox's k–ω model, Menter's two‐equation shear‐stress‐transport model, and the one‐equation model of Spalart and Allmaras. The objective of the study is to establish the prediction accuracy of these turbulence models with respect to axisymmetric separating flows, and flows of high streamline curvature. At the same time, the study establishes the minimum spatial resolution requirements for each of these turbulence closures, and identifies the proper low‐Mach‐number preconditioning and artificial diffusion settings of a Reynolds‐averaged Navier–Stokes algorithm for optimum rate of convergence and minimum adverse impact on prediction accuracy. Copyright © 2003 John Wiley & Sons, Ltd.
Phosphorylation of starch and dextrin by dry‐heating in the presence of phosphate, and their calcium phosphate‐solubilizing ability
Authors: Nakano Tomoki , Salvador Arvin S. , Tamochi Jiro , Sugimoto Yasushi , Ibrahim Hisham R. , Toba Yasuhiro , Aoe Seiichiro , Kawakami Hiroshi , Aoki Takayoshi
Published: August 2003

Starch and dextrin were phosphorylated by dry‐heating in the presence of phosphate, and their properties were examined. The phosphorylation of starch was accelerated with decreasing moisture, rising incubation temperature and prolongation of the incubation period. However, a rise in incubation temperature, and lengthened incubation period caused increased browning and degradation. A decrease in the pH from 5.5 to 3.0 resulted in a modest increase of phosphorylation, but also marked browning and degradation. When potato starch was phosphorylated at 140°C and pH 5.5 for 24 h, its phosphorus content was increased up to 3.47%, with fewer side reactions. Phosphorlylated starch and dextrin had calcium phosphate‐solubilizing abitity. Phosphorylated dextrin with 2.42% phosphorus had about half the calcium phosphate‐solubilizing ability of casein phosphopeptide (CPP). The possibility of substituting of phosphorylated starch and dextrin for CPP as a calcium phosphate‐absorption enhancing material is discussed herein.
Bayesian analysis of multilocus association in quantitative and qualitative traits
Authors: Kilpikari Riika , Sillanpää Mikko J.
Published: August 2003

A Bayesian model‐based method for multilocus association analysis of quantitative and qualitative (binary) traits is presented. The method selects a trait‐associated subset of markers among candidates, and is equally applicable for analyzing wide chromosomal segments (genome scans) and small candidate regions. The method can be applied in situations involving missing genotype data. The number of trait loci, their marker positions, and the magnitudes of their gene effects (strengths of association) are all estimated simultaneously. The inference of parameters is based on their posterior distributions, which are obtained through Markov chain Monte Carlo simulations. The strengths of the approach are: 1) flexible use of oligogenic models with unknown number of loci, 2) performing the estimation of association jointly with model selection, and 3) avoidance of the multiple testing problem, which typically complicates the approaches based on association testing. The performance of the method was tested and compared to the multilocus conditional search procedure by analyzing two simulated data sets. We also applied the method to cystic fibrosis haplotype data (two‐locus haplotypes), where gene position has already been identified. The method is implemented as a software package, which is freely available for research purposes under the name BAMA.Genet Epidemiol25:122–135, 2003. © 2003 Wiley‐Liss, Inc.
Optimal two‐stage genotyping in population‐based association studies
Authors: Satagopan Jaya M. , Elston Robert C.
Published: August 2003

We propose a cost‐effective two‐stage approach to investigate gene‐disease associations when testing a large number of candidate markers using a case‐control design. Under this approach, all the markers are genotyped and tested at stage 1 using a subset of affected cases and unaffected controls, and the most promising markers are genotyped on the remaining individuals and tested using all the individuals at stage 2. The sample size at stage 1 is chosen such that the power to detect the true markers of association is 1−β1 at significance level α1. The most promising markers are tested at significance level α2 at stage 2. In contrast, a one‐stage approach would evaluate and test all the markers on all the cases and controls to identify the markers significantly associated with the disease. The goal is to determine the two‐stage parameters (α1, β1, α2) that minimize the cost of the study such that the desired overall significance is α and the desired power is close to 1−β, the power of the one‐stage approach. We provide analytic formulae to estimate the two‐stage parameters. The properties of the two‐stage approach are evaluated under various parametric configurations and compared with those of the corresponding one‐stage approach. The optimal two‐stage procedure does not depend on the signal of the markers associated with the study. Further, when there is a large number of markers, the optimal procedure is not substantially influenced by the total number of markers associated with the disease. The results show that, compared to a one‐stage approach, a two‐stage procedure typically halves the cost of the study. Genet Epidemiol 25:149–157, 2003. © 2003 Wiley‐Liss, Inc.
Lysine 445 is a molecular indicator of subunit‐specific AMPA receptor binding domains
Authors: Sessoms Sikes J. Suzanne , Verdoorn Todd
Published: August 2003

Despite strong homology between subunits of AMPA‐type glutamate receptors, heteromeric assemblies in different brain regions vary in subunit composition and functional properties. We have previously shown that charge substitution at K445 decreases the apparent potency of AMPA for GluR‐A receptors, although an analogous mutation is a low conductance B subunit of AB heteromers did not diminish AMPA potency. To examine the subunit selectivity of K445, we now measure the apparent potency of AMPA and glutamate at recombinant homomeric receptors containing the high‐conductance, unedited (586Q) GluR‐B subunit (GluR‐B(Q)) using two‐electrode voltage‐clamp. We find the decrease in apparent potency of AMPA is recapitulated for homomeric GluR‐B(Q)K449E receptors, and is rescued by coexpression with wild‐type GluR‐A. These data are consistent with the hypothesis that AMPAR subunit composition is critical to agonist‐dependent receptor activation, and suggest that GluR‐A plays a dominant role in mediating
receptor activation by AMPA.
Personality of children with accident‐related injuries
Authors: Vollrath Margarete , Landolt Markus A. , Ribi Karin
Published: August 2003

Previous studies based on a variety of behaviour, temperament, and personality measures identified a pattern of over‐activity, impulsiveness, emotional instability, and aggressiveness in children who are prone to accidents. The present study is the first to study accident‐prone children by means of a comprehensive test for the assessment of the Five Factor model (Hierarchical Personality Inventory for Children (HiPIC) (Mervielde & De Fruyt, 1999). 118 children, aged 6–15 years, who were hospitalized due to an accident‐related injury, were contrasted with 184 school‐children of the same age. Lower socio‐economic status was under‐represented in both groups. Children who were exposed to accidents had higher scores on the facets of energy, optimism, and non‐shyness (Extraversion domain), and lower scores on the facets of concentration and achievement striving (Conscientiousness domain). There was no indication of higher aggressiveness, impulsiveness, or emotional instability in the group exposed to accidents, and there were no gender‐by‐accident interactions. Results suggest that there is a relatively benign pattern of personality traits that is related to greater accident hazard in children. Copyright © 2003 John Wiley & Sons, Ltd.
Thermally stable porous supramolecular frameworks based on the metal and π–π stacking directed self‐assembly of 2,6‐pyridyldicarboxylic acid bis‐4‐pyridylamide
Authors: Noveron Juan C. , Chatterjee Biswaroop , Arif Atta M. , Stang Peter J.
Published: August 2003

We report the formation of two thermally stable supramolecular structures based on 2,6‐pyridyldicarboxylic acid bis‐4‐pyridylamide (PyI) and bis(hexafluoroacetylacetonato)manganese(II) that exhibits a microporous structure with cavities bearing hydrogen bonding motifs that can enclathrate acetone and methanol molecules via well‐positioned hydrogen bonding interactions. Single‐crystal x‐ray diffraction in combination with thermogravimetric analysis and X‐ray powder diffraction (XRPD) studies were utilized to study the structure and thermal behavior of trans‐[Mn(hfacac)2(PyI)2]·2(CH3)2CO (1) and trans‐[Mn(hfacac)2(PyI)2]·2CH3OH (2). Our studies indicated that 1 and 2 are isostructural with respect to their supramolecular assembly and trap solvent molecules along the crystallographic b direction via the inwardly directed hydrogen bonding motifs of the PyI component. These solvent molecules can be thermally removed to generate a crystalline material with micropores bearing hydrogen bonding rich sites within an overall supramolecular matrix similar to 1 and 2. The removal of the guest solvent molecules is reversible and can be followed with XRPD. Copyright © 2003 John Wiley & Sons, Ltd.
Variation of the π‐electron delocalization in exocyclically substituted heptafulvene derivatives
Authors: Stępień Beata T. , Krygowski Tadeusz M. , Cyrański Michał K.
Published: August 2003

Eleven mono‐ and eight di‐exocyclically substituted heptafulvene derivatives were optimized at the B3LYP/6–311+G** level of theory. The aromaticity indices REC (ring energy content), Schleyer's NICS,3He NMR chemical shift and anisotropy of magnetic susceptibility and the geometry based descriptor HOMA were used to estimate the extent of cyclic π‐electron delocalization due to the substituent effect. A dramatic variation of these indices was found for electron‐accepting substituents indicating great sensitivity of the π‐electron structure of the ring. In the case of monosubstituted derivatives all indices exhibit a perfect or at least very good equivalence, whereas for disubstituted species the mutual correlations are markedly worse. Copyright © 2003 John Wiley & Sons, Ltd.
5‐Methoxyfuroxano[3,4‐d]pyrimidine: a highly reactive neutral electrophile
Authors: Remennikov Grigoriy Ya. , Kempf Bernhard , Ofial Armin R. , Polborn Kurt , Mayr Herbert
Published: August 2003

5‐Methoxyfuroxano[3,4‐d]pyrimidine (3) reacts with electron‐rich arenes and ethylene derivatives 4 at C‐7 to yield 7‐substituted 6,7‐dihydro‐5‐methoxyfuroxano[3,4‐d]pyrimidines (5). Kinetic investigations of these reactions showed that the rate constants can be described by the correlation equation log k(20 °C) = s(N + E). The electrophilicity parameter E(3) = −8.37 derived from the second‐order rate constants indicates that 3 reacts with nucleophiles of N ≥ 3. Copyright © 2003 John Wiley & Sons, Ltd.
Ab initio molecular dynamics studies on substitution vs electron transfer reactions of substituted ketyl radical anions with chloroalkanes: how do the two products form in a borderline mechanism?
Authors: Yamataka Hiroshi , Aida Misako , Dupuis Michel
Published: August 2003

We present a qualitative analysis, based on ab initio molecular dynamics (MD) calculations, of the SN2/ET mechanistic spectrum for three reactions: (1) HC(CN)O·− + CH3Cl, (2) HC(CN)O·− + (CH3)2CHCl and (3) H2CO·− + CH3Cl, passing through their SN2‐like transition states. Finite temperature (298 K) direct MD simulations indicate that the trajectories for reaction (1) appear to have a propensity towards SN2 products, the propensity for trajectories for reaction (2) seems to be towards ET products, whereas trajectories for reaction (3) appear to show no particular propensity towards either ET or SN2 products. The mechanistic diversity is consistent with the electron‐donating ability of the ketyl species and steric bulkiness of chloroalkanes. We find that the trajectories have characteristics that reflect strongly the types of process [SN2 trajectories in reactions (1) and (3) vs ET trajectories in reactions (2) and (3)]. Trajectories that lead to SN2 products are simple with C—C bond formation and C—Cl bond breaking essentially completed within 50 fs. By contrast, trajectories leading to ET products are more complex with a sudden electron reorganization taking place within 15–30 fs and the major bonding changes and electron and spin reorganizations completed after 250 fs. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamics of reaction of ion pairs in aqueous solution: racemization of the chiral ion pair intermediate of solvolysis of (S)‐1‐(4‐methylphenyl)ethylpentafluorobenzoate
Authors: Tsuji Yutaka , Mori Tetsuo , Toteva Maria M. , Richard John P.
Published: August 2003

The chiral ester
(S)‐1‐(4‐methylphenyl)ethyl pentafluorobenzoate, (S)‐1‐OC(O)C6F5, was prepared and a value of krac = 8.5 × 10−7 s−1 was determined for the rate constant for its racemization to
(R)‐1‐OC(O)C6F5 in 50:50 (v/v) trifluoroethanol–water (I = 0.50, NaClO4). This rate constant is 12 times smaller than ksolv = 1.06 × 10−5 s−1 for the stepwise solvolysis of 1‐OC(O)C6F5, which shows that inversion of the ion‐pair intermediate is a relatively rare event during solvolysis in a largely aqueous solvent, and two times smaller than kiso = 1.6 × 10−6 s−1 for degenerate isomerization which exchanges the position of the ester bridging and non‐bridging oxygens of 1‐OC(O)C6F5. A simple relationship is derived between the empirical rate constant ratio krac/kiso and the microscopic rate constants for reaction of the ion‐pair intermediate within its solvation shell. Substitution of estimated rate constants for reactions of the 1‐(4‐methylphenyl)ethyl carbocation–pentafluorobenzoate anion pair into this equation gives ki = 1.5 × 1010 s−1 for inversion of the chiral ion pair, which is similar to k−d = 1.6 × 1010 s−1 for its separation to free ions. Copyright © 2003 John Wiley & Sons, Ltd.
Kinetic and mechanistic aspects of the direct photodegradation of atrazine, atraton, ametryn and 2‐hydroxyatrazine by 254 nm light in aqueous solution
Authors: Azenha M. E. D. G. , Burrows H. D. , Canle L. M. , Coimbra R. , Fernández M. I. , García M. V. , Peiteado M. A. , Santaballa J. A.
Published: August 2003

Atrazine (1), Atraton (2) and Ametryn (3) are photodegraded upon 254 nm irradiation, yielding 2‐OH‐atrazine (4) as a photoproduct. Dealkylation products are also generated, and 4‐ethylamino‐6‐isopropylamino‐(1,3,5)‐triazine was also found as a photoproduct of 3. The main photoreaction is proposed to be an addition–elimination, yielding 4, which subsequently photodegrades. The ease of photodegradation depends on the electron availability at position C‐2, the observed order of photoreactivity being 1 > 3 > 4 > 2. Copyright © 2003 John Wiley & Sons, Ltd.
Supramolecular catalysis induced by polysaccharides. Homogeneous hydrolysis of p‐nitrobenzyl amylose xanthate
Authors: Humeres Eduardo , Gerônimo Vanilde F. , Zwirtes Inês R. , Mazera Edio , Aliev Abil E.
Published: August 2003

p‐Nitrobenzyl amylose xanthate (AmXNB) was synthesized and characterized by 13C NMR spectroscopy in solution and the solid state. The degree of substitution (DS), calculated from the sulfur content, was 7.0, and this value was similar to that obtained from solid‐state 13C NMR using the signal of C‐1 as internal standard. The hydrolysis of AmXNB was studied in 10% (v/v) DMSO with µ = 0.5 (KCl) at 25 °C. The basic hydrolysis was pseudo‐first order, but the water‐catalyzed hydrolysis in the pH range 7–9 showed a biphasic plot of ln (ΔAbsorbance) vs time, as has been observed for cellulose xanthate esters, occurring through two parallel reactions with rate constants k′H2O (fast) = 5.3 × 10−5 s−1 and k″H2O (slow) = 3.3 × 10−6 s−1. The fast hydrolysis was more than three orders of magnitude faster than that of the O‐ethyl analog. The activation parameters were ΔH≠ = 20.5 kcal mol−1 and ΔS≠ = +10 cal K−1 mol−1. They showed that the acceleration of the fast hydrolysis of AmXNB and cellulose analogs is due to an entropy of activation effect. There is a linear increase of logk′H2O (fast) with increase in the concentration of the small Li+ ion that produces an increase of the 3‐D hydrogen‐bond network of water while the large singly charged iodide ion has a considerable inverse effect. These results are strongly consistent with the theory that the supramolecular catalysis induced by modified polysaccharide esters is due to the 3‐D hydrogen‐bond network of the water in the solvation shell. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of anti‐inﬂammatory potential of Pavetta indica Linn. leaf extract (family: Rubiaceae) in rats
Authors: Mandal Subhash C. , Mohana Lakshmi S. , Ashok Kumar C. K. , Sur Tapas K. , Boominathan R.
Published: August 2003

The anti‐inﬂammatory potential of methanol extract of Pavetta indica Linn. leaves (Family: Rubiaceae) was evaluated against several models of inﬂammation such as carragenin, histamine and dextran induced pedal inﬂammation in rats. The extract showed 48.41%, 41.10% and 24.22% inhibition respectively; when compared to that of control animals. The effect was comparable with that of the standard drug indomethacin, a standard non‐steroidal anti‐inﬂammatory drug. Simultaneous subplantar administration of the extract and carrageenin in a mixture helps in differentiating true anti‐inﬂammatory action from an apparent anti‐inﬂammatory effect due to counter‐irritant activity. The methanol extract also effectively and signiﬁcantly reduced cotton pellet induced granuloma. The percentage of inhibition was 62.78 at the dose 500 mg/kg, thereby suggesting its activity in the proliferative phase of the inﬂammatory process. Copyright © 2003 John Wiley & Sons, Ltd.
Antioxidant properties of scopoletin isolated from Sinomonium acutum
Authors: Shaw Chin‐Ying , Chen Chen‐Hui , Hsu Chih‐Chieh , Chen Chien‐Chih , Tsai Ying‐Chieh
Published: August 2003

Scopoletin was isolated from Sinomonium acutum and studied using four experimental models designed to assess antioxidant properties. The results indicated that scopoletin scavenged superoxide anion in the xanthine/xanthine oxidase reaction system in a concentration‐dependent manner, but did not inhibit xanthine oxidase. Scopoletin may therefore be responsible for the superoxide anion scavenging activity seen in Sinomonium acutum extracts and may be of use in preventing superoxide anion‐induced damage in vivo. Copyright © 2003 John Wiley & Sons, Ltd.
Analgesic and anti‐inﬂammatory activity of the leaf essential oil of Laurus nobilis Linn.
Authors: Sayyah M. , Saroukhani G. , Peirovi A. , Kamalinejad M.
Published: August 2003

The leaf essential oil of Laurus nobilis Linn. (Lauraceae) has been evaluated for antinociceptive and anti‐inﬂammatory activities in mice and rats. The essential oil exhibited: (1) a signiﬁcant analgesic effect in tail‐ﬂick and formalin tests; (2) a dose‐dependent anti‐inﬂammatory effect in the formalin‐induced edema and (3) a moderate sedative effect at the anti‐inﬂammatory doses. The analgesic and anti‐inﬂammatory effect of the essential oil was comparable to reference analgesics and non‐steroid anti‐inﬂammatory drugs: morphine and piroxicam. Present results make the essential oil worthy of further investigations. Copyright © 2003 John Wiley & Sons, Ltd.
Podophyllum hexandrum prevents radiation‐induced neuronal damage in postnatal rats exposed in utero
Authors: Sajikumar S. , Goel H. C.
Published: August 2003

Podophyllum hexandrum has been shown to mitigate radiation injuries and especially the haemopoietic syndrome in adult mice. To monitor the radiation‐induced changes in the nervous system, the neurons of postnatal young mice and their modiﬁcation by P. hexandrum, were studied histologically for differences in the apical and basal dendritic branching and intersections in the CA1 neurons of the hippocampal region of rats which were delivered a 2 Gy gamma dose while in utero (day 17 of gestation). Irradiation signiﬁcantly reduced the dendritic branching and intersections but pre‐irradiation administration of the extract of P. hexandrum (i.p. 200 mg/kg/b.w., 2 h) reduced the damage in postnatal young mice. These studies indicate that P. hexandrum provides protection to neurons against radiation‐induced damage and the mechanism of neuronal damage and its repair need to be investigated further. Copyright © 2003 John Wiley & Sons, Ltd.
Alkaloids from Brugmansia arborea (L.) Lagerhein reduce morphine withdrawal in vitro
Authors: Capasso Anna , de Feo Vincenzo
Published: August 2003

Traditional medicine is a primary source for the study of medicinal plants. In some countries, knowledge about the therapeutic use of medicinal plants is very deep and very often ‘magical’ plants also are used to diagnose and treat illnesses. The study of these plants can help in the research of metabolites active on the central and peripheral nervous system.

Brugmansia arborea (L.) Lagerheim (Solanaceae) is used in the northern Peruvian Andes for magic–therapeutic purposes and the present study examined the effect of three pure tropane alkaloids from Brugmansia arborea (L.) Lagerhein (Solanaceae) on morphine withdrawal in vitro. All the tropane alkaloids isolated from Brugmansia arborea (L.) (10−7, 5 × 10−7, 10−6 m) signiﬁcantly and in a concentration dependent manner reduced morphine withdrawal.

The results of the present study suggest that these alkaloids may be a potential anti‐additive agent. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of the antimalarial properties and standardization of tablets of Azadirachta indica (Meliaceae) in mice
Authors: Isah A. B. , Ibrahim Y. K. E. , Iwalewa E. O.
Published: August 2003

The antimalarial activities of the tablet suspension of the bark and leaf of Azadirachta indica were evaluated on Plasmodium yoelli nigeriensis infected mice. The tablet suspensions exhibited high prophylactic, mode‐rate suppressive and a very minimal curative schizonticidal effect. No animal was cured of the infection in the curative test and there was not much increase in the survival time of the animals compared with the control. The tablet suspensions from the leaf and bark at a concentration of 800 mg/kg and chloroquine at a concentration of 62.5 mg/kg body weight produced average percentage (%) parasitaemia of 79.6%, 68.2% and 99.5% for leaf, bark and chloroquine, respectively, in chemosuppression. Also in the prophylactic treatment, the tablet suspensions at 800 mg/kg and pyrimethamine at a concentration of 0.35 mg/kg gave an average parasitaemia reduction of 75.3%, 65.6% and 98.3% for the leaf, bark and pyrimethamine, respectively.

There was a clear indication that both tablet suspensions from the leaf and bark possess antimalarial activity and a suspension from the former is relatively more effective than the bark. Extrapolation of the results from the antimalarial activity of the tablet suspension of the crude plant parts showed that an adult human would need to ingest a minimum of 48 g of the powdered plant material per day, an amount that is impracticable.

A survival index value of 0.33 was obtained with the 800 mg/kg dose level, indicating that the tablet suspension has some moderate beneﬁcial effect. Copyright © 2003 John Wiley & Sons, Ltd.
Anti‐tumour and immuno‐stimulating activities of the fruiting bodies of Paecilomyces japonica, a new type of Cordyceps spp.
Authors: Shin Kuk Hyun , Lim Soon Sung , Lee Sanghyun , Lee Yeon Sil , Jung Sang Hoon , Cho Sae Yun
Published: August 2003

The anti‐tumor and immuno‐stimulating activities of the fruiting bodies of Paecilomyces japonica (PJ), grown on silk‐worm larvae and of Cordyceps sinensis (CS), a wild form of Cordyceps Fungi, were investigated. Ethanol extracts of both fungi, when administered for 9 consecutive days, at 50 and 100 mg/kg i.p., caused a signiﬁcant increase in life span and a signiﬁcant decrease in tumor weights and volumes, in mice inoculated with Sarcoma‐180 tumor cells. Both fungal extracts were demonstrated to exhibit phagocytosis enhancing activity as measured by carbon clearance in mice. PJ extracts, when administered i.p. at 50 mg/kg/day for 3 consecutive days, exhibited a signiﬁcant enhancement of phagocytosis, its potency as expressed by the regression coefﬁcient ratio, RCtr/RCc, being 1.64 (the phagocytosis index = 2). This was approximately the same for that of zymosan (RCtr/RCc = 1.55, PI = 2), a typical phagocytosis enhancer, whereas CS extracts exhibited a moderate phagocytosis enhancing activity at the same dose level (RCtr/RCc = 1.30, PI = 1). Both fungal extracts caused a signiﬁcant increase in an acid phosphatase activity, representing lysosomal enzymes, in macrophages at 20 and 100 µg/ml in vitro, in compliance with in vivo results. These results suggest that the anti‐tumor activity of both fungi might be related to an immuno‐stimulating function. Copyright © 2003 John Wiley & Sons, Ltd.
Ephedra in perspective – a current review
Authors: Abourashed Ehab A. , El‐Alfy Abir T. , Khan Ikhlas A. , Walker Larry
Published: August 2003

Although the traditional use of Ephedra ‘ma huang’ has been established for thousands of years, its resurgencein the US as a herbal dietary supplement is currently a matter of national controversy. At the heart of the debate are three important questions: (1) the identity and composition of Ephedra products with regard to ephedrine and related alkaloids; (2) the potential therapeutic utility of Ephedra supplements for weight loss or performance enhancement; and (3) potential health risks associated with such uses of Ephedra, particularly in sensitive individuals or in cases of intentional abuse for its stimulant properties. This review surveys the literature on Ephedra with regard to traditional uses, botany, chemistry, analytics, pharmacological effects and health risks. A brief discussion of the central issues in the current debate on the regulation of Ephedra in the United States is included as this is where most of the problems have occurred to date. Copyright © 2003 John Wiley & Sons, Ltd.
Prediction of the Vapor Pressure Boiling Point, Heat of Vaporization and Diffusion Coefficient of Organic Compounds
Authors: Hilal S. H. , Karickhoff S. W. , Carreira L. A.
Published: August 2003

The prototype computer program SPARC has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC solute‐solute physical process models have been developed and tested for vapor pressure (at any temperature), heat of vaporization (at 25C and the boiling point), diffusion coefficient (at 25C) and boiling point (at any pressure) for a relatively large number of organic molecules. The RMS deviation error of the predicted the vapor pressures, heats of vaporization (at any temperature) and boiling points (at any pressure) were close to the intralaboratory experimental errors.
A Combinatorial Approach to the Variable Selection in Multiple Linear Regression: Analysis of Selwood et al. Data Set – A Case Study
Authors: Prabhakar Yenamandra S.
Published: August 2003

A combinatorial protocol (CP) is introduced here to interface it with the multiple linear regression (MLR) for variable selection. The efficiency of CP‐MLR is primarily based on the restriction of entry of correlated variables to the model development stage. It has been used for the analysis of Selwood et al data set [16], and the obtained models are compared with those reported from GFA [8] and MUSEUM [9] approaches. For this data set CP‐MLR could identify three highly independent models (27, 28 and 31) with Q2 value in the range of 0.632–0.518. Also, these models are divergent and unique. Even though, the present study does not share any models with GFA [8], and MUSEUM [9] results, there are several descriptors common to all these studies, including the present one. Also a simulation is carried out on the same data set to explain the model formation in CP‐MLR. The results demonstrate that the proposed method should be able to offer solutions to data sets with 50 to 60 descriptors in reasonable time frame. By carefully selecting the inter‐parameter correlation cutoff values in CP‐MLR one can identify divergent models and handle data sets larger than the present one without involving excessive computer time.
Affinity of ribosomal protein S8 from mesophilic and (hyper)thermophilic archaea and bacteria for 16S rRNA correlates with the growth temperatures of the organisms
Authors: Gruber Thomas , Köhrer Caroline , Lung Birgit , Shcherbakov Dmitri , Piendl Wolfgang
Published: August 2003

The ribosomal protein S8 plays a pivotal role in the assembly of the 30S ribosomal subunit. Using filter binding assays, S8 proteins from mesophilic, and (hyper)thermophilic species of the archaeal genus Methanococcus and from the bacteria Escherichia coli and Thermus thermophilus were tested for their affinity to their specific 16S rRNA target site. S8 proteins from hyperthermophiles exhibit a 100‐fold and S8 from thermophiles exhibit a 10‐fold higher affinity than their mesophilic counterparts. Thus, there is a striking correlation of affinity of S8 proteins for their specific RNA binding site and the optimal growth temperatures of the respective organisms. The stability of individual rRNA‐protein complexes might modulate the stability of the ribosome, providing a maximum of thermostability and flexibility at the growth temperature of the organism.
Regulation of ubiquitous 6‐phosphofructo‐2‐kinase by the ubiquitin‐proteasome proteolytic pathway during myogenic C2C12 cell differentiation
Authors: Riera Lluı́s , Obach Mercè , Navarro-Sabaté Aurea , Duran Joan , Perales Jose C , Viñals Francesc , Rosa Jose Luis , Ventura Francesc , Bartrons Ramon
Published: August 2003

6‐Phosphofructo‐2‐kinase catalyzes the synthesis and degradation of fructose 2,6‐bisphosphate, activator of phosphofructokinase‐1 and inhibitor of fructose 1,6‐bisphosphatase. These properties confer to this bifunctional enzyme a key role in the control of glycolysis and gluconeogenesis. Several mammalian isozymes generated by alternative splicing from four genes, designated pfkfb1–4, have been identified. The results presented in this study demonstrate the expression of the pfkfb3 gene in C2C12 cells and its downregulation during myogenic cell differentiation. We also show that the decrease of ubiquitous 6‐phosphofructo‐2‐kinase isozyme levels, product of pfkfb3 gene, is due to its enhanced degradation through the ubiquitin‐proteasome proteolytic pathway.
Oligomerization of human presenilin‐1 fragments
Authors: Hébert Sébastien S , Godin Chantal , Lévesque Georges
Published: August 2003

To gain insight into presenilin‐1 (PS1) structural aspects, we explored the structure–function relationship of its N‐ and C‐terminal (NTF and CTF, respectively) complexes. We demonstrated that both NTF and CTF act as independent but inter‐changing binding units capable of binding each other (NTF/CTF) or their homologues (NTF/NTF; CTF/CTF). The Alzheimer's disease‐associated PS1 mutations Y115H and M146L do not affect their ability to hetero‐ and/or homodimerize, thus conserving their basic integrity and function(s). These results suggest that PS1 associates intra‐molecularly to form higher order complexes, which may be needed for endoproteolytic cleavage and/or γ‐secretase‐associated activity.
Transposition and targeting of the prokaryotic mobile element IS30 in zebrafish
Authors: Szabó Mónika , Müller Ferenc , Kiss János , Balduf Carolin , Strähle Uwe , Olasz Ferenc
Published: August 2003

We provide evidence that a prokaryotic insertion sequence (IS) element is active in a vertebrate system. The transposase of Escherichia coli element IS30 catalyzes both excision and integration in extrachromosomal DNA in zebrafish embryos. The transposase has a pronounced target preference, which is shown to be modified by fusing the enzyme to unrelated DNA binding proteins. Joining the transposase to the cI repressor of phage λ causes transposition primarily into the vicinity of the λ operator in E. coli, and linking to the DNA binding domain of Gli1 also directs the recombination activity of transposase near to the Gli1 binding site in zebrafish. Our results demonstrate the possibility of fusion transposases to acquire novel target specificity in both prokaryotes and eukaryotes.
Rapamycin inhibits GM‐CSF‐induced neutrophil migration
Authors: Gomez-Cambronero Julian
Published: August 2003

The molecular mechanisms that govern cell movement are the subject of intense study, as they impact biologically and medically important processes such as leukocyte chemotaxis and angiogenesis, among others. We demonstrate that leukocyte chemotaxis is prevented by the macrolide immunosuppressant rapamycin, a specific inhibitor of the mammalian target of rapamycin (mTOR)/ribosomal p70‐S6 kinase (p70S6K) pathway. Both neutrophil chemotaxis and chemokinesis elicited by granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) were strongly inhibited by rapamycin with an IC50 of 0.3 nM. Inhibition, although at a higher dose, was also observed when the chemoattractant was interleukin‐8. As for the mechanism, rapamycin targeted the increase of phosphorylation of p70S6K due to GM‐CSF treatment, as demonstrated with specific anti‐p70S6K immunoprecipitation and subsequent immunoblotting with anti‐T421/S424 antibodies. Rapamycin also inhibited GM‐CSF‐induced actin polymerization, a hallmark of leukocyte migration. The specificity of the effect of rapamycin was confirmed by the use of the structural analog FK506, which did not have a significant effect on chemotaxis but effectively rescued rapamycin‐induced p70S6K inhibition. This was expected from a competitive effect of both molecules on FK506‐binding proteins (FKBP). Additionally, GM‐CSF‐induced chemotaxis was completely (>90%) blocked by a combination of rapamycin and the MAPK kinase (MEK) inhibitor PD‐98059. In summary, the results presented here indicate for the first time that rapamycin, at sub‐nanomolar concentrations, inhibits GM‐CSF‐induced chemotaxis and chemokinesis. This serves to underscore the relevance of the mTOR/S6K pathway in neutrophil migration.
NF‐kB signaling blockade abolishes implant particle‐induced osteoclastogenesis
Authors: Clohisy John C. , Hirayama Teruhisa , Frazier Elfaridah , Han Suk‐Ku , Abu‐Amer Yousef
Published: August 2003

In this study we investigated the effect of NF‐kB signaling blockade on polymethylmethacrylate (PMMA) particle‐induced osteoclastogenesis in vitro. We first established effective blockade of NF‐kB activity as tested by electrophoretic mobility shift assays (EMSA). Particle‐induced NF‐kB activation in murine osteoclast precursor cells (CSF‐1‐dependent bone marrow macrophages) was markedly reduced by co‐treatment of the cells with the NF‐kB inhibitors N‐tosyl‐L‐phenylalanine chloromethyl ketone (TPCK) and Calpain Inhibitor I (CPI). This inhibition of NF‐kB activity was associated with blockade of p50 NF‐kB subunit nuclear trans‐location. We then established a direct NF‐kB inhibition approach by utilizing a TAT‐bound, mutant IkB (TAT:IkB46‐317), and demonstrated an inhibitory effect evidenced by decreased NF‐kB DNA binding activity. Having established that these strategies (TPCK, CPI, TAT: IkB46‐317) effectively block NF‐kB activation, we next investigated the effect of these agents on particle‐stimulated osteoclast formation. PMMA particle stimulation of mature osteoclast formation from RANKL‐primed osteoclast precursor cells was blocked by all three inhibitors. To further test the efficacy of NF‐kB blockade, experiments were performed with the TAT:IkB46‐317 mutant peptide in whole bone marrow cultures that contain supporting stromal cells. Again, this inhibitor efficiently blocked particle‐induced osteoclastogenesis. Thus, we have shown that pharmaceutical and molecular blockade of NF‐kB activation inhibits PMMA particle‐directed osteoclastogenesis in vitro. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The absorption of sound in seawater in relation to the estimation of deep-water fish biomass
Authors: Doonan Ian J , Coombs Roger F , McClatchie Sam
Published: August 2003

It is well known that the acoustic estimation of fish abundance requires an estimate of the absorption of sound in seawater. Any errors in this factor will lead to errors in abundance estimates that increase with range. Concerns over the accuracy of the widely used relationship of Francois and Garrison (Journal of the Acoustical Society of America, 72: 896–907; Journal of the Acoustical Society of America, 72: 1879–1890) led to a new analysis of the data they used and a reconsideration of the relationship as a whole.

A major component of sound absorption by seawater is the relaxation frequency of MgSO4, for which there are at least five equations in the literature. We review these and our analysis uses the relaxation equation that best fits the sound-absorption data using modern regression methods. We propose a new equation for the range of frequencies used in fish abundance (10–120 kHz) based on this analysis. For a typical New Zealand deep-water fishery carried out at 38 kHz the new equation gives a biomass 17% lower than that yielded by Francois and Garrison. Whilst we believe that the new equation gives more accurate results for the range of frequencies used in fish abundance, there remains much uncertainty which will only be resolved by the collection of new in situ sound-absorption data in this frequency range.
Low‐altitude signatures of magnetotail reconnection
Authors: Sotirelis Thomas , Newell Patrick , Meng Ching‐I. , Hairston Marc
Published: August 2003

Precipitating ions on the poleward edge of the nightside auroral oval sometimes exhibit sharp low‐energy cutoffs in their energy spectra. These truncated spectra are interpreted as signatures of magnetic reconnection in the magnetotail. The energy cutoff is frequently smoothly dispersed in latitude, allowing an interpretation in terms of quasi‐steady reconnection. These events are designated velocity‐dispersed ion structures (VDIS) type 2. Roughly one third of type 2 VDIS are accompanied by a sharp transition in the polar rain near the open‐closed boundary that aids in their analysis. From 886 nightside open‐closed boundary crossings by DMSP spacecraft, 148 type 2 VDIS were identified. They were found most frequently within 2–3 hours of midnight and for 40% of the open‐closed boundary crossings between 2200 and 0100 magnetic local time. Minimum variance fits to the cutoff energies and polar rain transition are performed on 49 of these events. For four of them the information from the minimum variance fit and observed convection velocities are used to infer distances to the reconnection site that varied from 30 to 80 RE. In three of these four cases a sharp transition in the convection velocity is observed, coincident with the arrival of ions from the reconnection site. If the reconnection region is viewed as a voltage source, lobe field lines can be insufficiently populated to carry the current necessary to impose the required voltage on the ionosphere. This explains the coincidence between the arrival of ions and a discontinuity in convection, that is, that an electric field from the reconnection site is imposed on the ionosphere but only after sufficient density populates the field lines that connect the regions.