bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Metals Based on BEDT‐TTF Radical Cation Salts with Magnetic Metal Oxalates as Counterions: β″‐(BEDT‐TTF)4A[M(C2O4)3]·DMF (A = NH4+, K+; M = CrIII, FeIII)
Authors: Prokhorova T.G. , Khasanov S.S. , Zorina L.V. , Buravov L.I. , Tkacheva V.A. , Baskakov A.A. , Morgunov R.B. , Gener M. , Canadell E. , Shibaeva R.P. , Yagubskii E.B.
Published: April 2003

Four (BEDT‐TTF)4A[M(C2O4)3]·DMF (DMF = dimethylformamide) salts of the organic donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT‐TTF) with metal oxalate anions, where A = (NH4, K), M = Cr (1); A = NH4, M = Fe (2); A = K, M = Cr (3); and A = NH4, M = Cr (3′) were prepared by electrocrystallization. These salts were characterized by single‐crystal X‐ray diffraction, electron spin resonance (ESR) spectroscopy, electrical resistance measurements, and electronic band structure calculations. The structures (with space group C2/c) consist of alternating β″‐type layers of BEDT‐TTF and an approximately hexagonal network formed by the A+ cation and the metal, with the solvent molecule, DMF, occupying hexagonal cavities in the anion layer. All of the salts are two‐dimensional organic metals down to 4.2 K and do not exhibit superconductivity. Their electronic band structure is similar to that of the known organic superconductor β″‐(BEDT‐TTF)4H3O[Fe(C2O4)3]·BN. The ESR spectra of salts 1 and 3′ are characterized by two resonances, one of Gaussian shape arising from the 3d localized electrons of Cr3+ and the other of Lorentzian (and Dysonian) shape due to the conduction electrons in the organic layers. On the basis of the calculated Fermi surfaces it is suggested that these salts could exhibit an interesting magnetoresistance behavior if disorder does not prevent the observation of the Shubnikov‐de Haas oscillations.
How families communicate about HNPCC genetic testing: Findings from a qualitative study
Authors: Peterson Susan K. , Watts Beatty G. , Koehly Laura M. , Vernon Sally W. , Baile Walter F. , Kohlmann Wendy K. , Gritz Ellen R.
Published: April 2003

Little is known about how hereditary nonpolyposis colon cancer (HNPCC) genetic counseling and testing information is communicated within at‐risk families. This article describes findings from a qualitative study of 39 adult members from five families with known HNPCC‐predisposing mutations. We evaluated how information from HNPCC genetic counseling and testing was disseminated in these families and how family members reacted to and acted on this information. We included family members who had been diagnosed with an HNPCC syndrome cancer, unaffected individuals who were at 50% risk of carrying a mutation, and their spouses. Participants included those who had undergone testing and those who had not. In general, all families had shared the news about an HNPCC mutation with at‐risk relatives. Communication about HNPCC genetic counseling and testing followed the norms used for conveying other nonurgent family news. Mutation noncarriers, nontesters, and those who were not biological relatives were less involved in discussing genetic counseling and testing and perceived these processes as less relevant to them. Although all family members were generally willing to share information about HNPCC, probands and mutation carriers informed extended family members and actively persuaded others to seek counseling or testing. Family members who were persuaded to seek those services by the proband were more likely to have counseling and testing and were more likely to seek those services sooner. Genetic counseling should attempt to identify the existing communication norms within families and ways that family members can take an active role in encouraging others to learn about their cancer risk and options for testing. Interventions may also need to emphasize the relevance of hereditary cancer information beyond the immediate family and to unaffected family members who may be central to the communication process (e.g., spouses of mutation carriers). © 2003 Wiley‐Liss, Inc.
Breast cancer survivors' attitudes about communication of breast cancer risk to their children
Authors: Miesfeldt Susan , Cohn Wendy F. , Jones Susan M. , Ropka Mary E. , Weinstein Jenine C.
Published: April 2003

Perceptions of breast cancer survivors regarding educating their children about hereditary breast cancer risk are underexplored. This study examined attitudes of early‐onset breast cancer survivors concerning whether, at what age, and how their children should be educated about potential risk for hereditary breast cancer. Women with breast cancer diagnosed < age 50 years between 1994 and 1997 were recruited from 34 Virginia hospitals. Participants responded to two surveys. The Family History Questionnaire permitted participant classification into two groups based on risk for hereditary disease, as determined by personal and family history. The Knowledge, Attitudes and Beliefs Questionnaire addressed participants' concerns regarding their children's breast cancer risk, perceptions of their children's concerns about their own risk, and whether, at what age, and from what source their children should be informed about their own risk. Among 267 participants, the average age was 47.5 years; 90% were Caucasian, 7% were African American; 52% had suspected hereditary breast cancer. Of participants with children, 81% indicated concern about their children's breast cancer risk; 55% reported that their children had expressed concern about their own risk. Seventy‐one percent of participants believed the age for informing children about hereditary breast cancer risk to be before 18 years. Eighty‐four percent cited the child's parents and 65% cited health professionals as a preferred information source. No differences in responses between participants with suspected hereditary breast cancer versus presumed sporadic breast cancer were noted. These data establish the need for educational resources regarding hereditary breast cancer for children of early‐onset breast cancer survivors. © 2003 Wiley‐Liss, Inc.
Titelbild: Cokristallisation mit Acetylen – Molekül‐Komplexe mit Aceton und Dimethylsulfoxid (Angew. Chem. 17/2003)
Authors: Boese Roland , Kirchner Michael T. , Billups W. Edward , Norman Lewis R.
Published: April 2003

Durch In‐situ‐Kristallisation in einer Kapillare unter Druck mithilfe eines CO2‐Lasers wurden zwei simultan auftretende Phasen von Acetylenkomplexen erhalten. Deren Reflexmuster sind bei der Messung überlagert und bilden den Sternenhimmel im Hintergrund des Titelbildes. In den roten Reflexen der 1:1‐Phase können zwei Zellparameter direkt abgelesen werden. In den weißen Reflexen der 1:2‐Phase ist das reziproke Gitter erkennbar, wenn das Titelbild von der Seite betrachtet wird. Mehr dazu erfahren Sie in der Zuschrift von R. Boese et al. auf S. 2005 ff.
The effects of sediment deposits from Namibian diamond mines on intertidal and subtidal reefs and rock lobster populations
Authors: Pulfrich Andrea , Parkins Colleen A. , Branch George M. , Bustamante Rodrigo H. , Velásquez Claudio R.
Published: April 2003

Extensive diamond mining occurs on land and in the sea on the west coasts of South Africa and Namibia, raising fears that diamond‐mining activities may impact commercial rock‐lobster fisheries and benthic communities. To explore this possibility, the effects of the diamond‐mining fines‐discharge on intertidal and subtidal rocky‐shore communities and on the population structure of the rock lobster Jasus lalandii were assessed at Elizabeth Bay.

Sampling over six years at sites covering a range of wave exposures compared impacted sites with comparable reference sites never exposed to the fines. Percentage cover and densities of benthic organisms were recorded on both intertidal and subtidal reefs. Rock‐lobster abundance was estimated from counts and catch‐per‐unit‐effort, and their length frequencies and sex ratios compared in impacted and reference areas.

The deposition of fines had no effect at wave‐exposed sites, but did impact intertidal and subtidal communities at sheltered localities where fines accumulated because wave action was insufficient to disperse them. Reductions of grazers, proliferation of algae and increased dominance by filter‐feeders were recorded at the impacted sites and persisted throughout the monitoring programme. Differences in community structure associated with different levels of wave exposure were, however, greater than those produced by depositing fines. The detected effects of fines‐deposits on the benthos were local and likely to be reversible after cessation of mining.

The fines‐deposit had no detectable effects on the sex‐ratio, size or abundance of rock lobsters, indicating that there is no conflict between the deposition of fines and the fishery for rock lobsters, although substantial inter‐site variability makes it difficult to regard the results as definitive.

Copyright © 2002 John Wiley & Sons, Ltd.
Intracerebroventricular injection of the terminal complement complex causes inflammatory reaction in the rat brain
Authors: Casarsa Claudia , Luigi Ada De , Pausa Mario , Simoni Maria Grazia De , Tedesco Francesco
Published: April 2003

To investigate the effect of the terminal complement complex (TCC) on the central nervous system, we injected both the cytolytically active and the inactive complexes into the lateral ventricle of rats. Both complexes promoted accumulation of leukocytes into the cerebrospinal fluid at 4–6 h post‐injection. The cells recovered at this time were mostly polymorphonuclear leukocytes (PMN) that were partially replaced by mononuclear cells at 12 h. A direct contribution of the complexes to the in‐vivo migration of leukocytes was ruled out by their inability to be chemotactic for rat PMN. Contaminating C5a is unlikely to be responsible for the effect of TCC because it failed to mobilize leukocytes when injected into the lateral ventricle. Histological analysis of rat brains 6 hoursafter injection of TCC revealed marked leukocyte infiltration of the choroid plexus, increased expression of intercellular adhesion molecule‐1 and egression of leukocytes out of the meningeal vessels. The cerebrospinal fluid of rats treated with TCC exhibited chemotactic activity for rat PMN and increased levels of growth related oncogen/cytokine‐induced neutrophil chemoattractant‐1 and monocyte chemoattractant protein‐1 preceding the accumulation of leukocytes. Elevated concentration of IL‐1β was also found in the cerebrospinal fluid and in periventricular areas of rats treated with TCC.
Organ‐specific and stage‐dependent control of Leishmania major infection by inducible nitric oxide synthase and phagocyte NADPH oxidase
Authors: Blos Martin , Schleicher Ulrike , Rocha F. Janaina Soares , Meißner Udo , Röllinghoff Martin , Bogdan Christian
Published: April 2003

In the Leishmania major mouse model of cutaneous leishmaniasis inducible nitric oxide synthase (iNOS) is crucial for the killing of the parasite in the skin and draining lymph node. However, the effector mechanism operating against L. major in the spleen is unknown. As reactive oxygen intermediates might play a role, we analyzed macrophages and mice lacking the gp91phoxsubunit of the phagocyte NADPH oxidase (phox) for their ability to combat an infection with L. major. Macrophages from wild‐type and gp91phox–/– mice had an equal capacity to killL. major after activation by cytokines. Unlike iNOS, the activity of phox was dispensable for the resolution of the acute skin lesions and exerted only a limited effect on the containment of the parasites in the draining lymph node, but was essential for the clearance of L. major in the spleen. During the chronic phase of infection, parasites persisted at high levels in gp91phox–/– mice, and cutaneous lesions re‐emerged in approximately 60% of these mice. gp91phox deficiency did not impair the expression of iNOS or the production of TNF and IFN‐γ. These results demonstrate that iNOS and phox are both required for the control of L. major in vivo and display unexpected organ‐ and stage‐specific anti‐leishmanial effects.
Low‐avidity recognition by CD4+ T cells directed to self‐antigens
Authors: Gebe John A. , Falk Ben A. , Rock Kellee A. , Kochik Sharon A. , Heninger Anne K. , Reijonen Helena , Kwok William W. , Nepom Gerald T.
Published: April 2003

Self‐reactive T cells populate the peripheral immune system, and likely form the reservoir from which autoreactive cells are derived. We analyzed a panel of self and non‐self peptides presented by HLA‐DR4, a class II molecule associated with autoimmunity, by immunization of mice transgenic for HLA‐DR4. Significant structural avidity for T cell recognition, as measured by MHC class II tetramer binding to CD4+ T cells was only observed in mice immunized with the non‐self antigens. T cell hybridomas were generated from mice immunized with the naturally processed self‐peptide hGAD65 (552–572) and also from mice immunized with an influenza‐derived non‐self epitope (HA 306–318). T cells specific for the self peptide failed to bind tetramers and exhibited low functional avidity as measured by the peptide concentration required to reach half‐maximum proliferation values. In contrast, T cells specific for the non‐self HA (306–318) peptide exhibited high structural and functional avidity profiles. As recently described in studies of murine CD8+ T cell function, the predominance of low avidity recognition of self‐peptide epitopes may be a characteristic feature of CD4+ T cells responding to autoantigens.
Selective cross‐talk among natural cytotoxicity receptors in human natural killer cells
Authors: Augugliaro Raffaella , Parolini Silvia , Castriconi Roberta , Marcenaro Emanuela , Cantoni Claudia , Nanni Marina , Moretta Lorenzo , Moretta Alessandro , Bottino Cristina
Published: April 2003

The cytolytic activity of human natural killer cells is induced by several triggering cell surface receptors upon interaction with specific cellular ligands. These receptors include NKp46, NKp30 and NKp44, collectively termed natural cytotoxicity receptors (NCR). Co‐operation among NCR has been shown to occur for optimal recognition and killing of most tumor target cells. In this study, we show that the mAb‐mediated engagement and clustering of one or another NCR results in the activation of an identical set of tyrosine kinases. These kinases are included in the signaling cascade leading to tyrosine phosphorylation of different receptor‐associated signal transducing molecules i.e. CD3ζ (associated with NKp46 and NKp30) and KARAP/DAP12 (associated with NKp44). In line with the notion that the engagement of inhibitory receptors prevents NCR‐mediated responses, we show that the engagement of CD94/NKG2A virtually abrogates the tyrosine phosphorylation of the NCR‐associated signaling molecules, i.e. it acts at the very early steps of the signaling cascade. Importantly, the engagement of a single NCR resulted in the activation of the signaling cascades associated with the other NCR. This "cross‐talk" is confined to NKp46, NKp30 and NKp44 since neither CD16‐nor KIR2DS4‐associated signaling polypeptides were phosphorylated following the NCR engagement. These results suggest that a functional cross‐talk specifically occurs among different NCR, possibly resulting in the amplification of the activating signals.
Cobalt(III) Tetraazamacrocyclic Complexes with Pendant Amino Groups: Synthesis, Structure and Electrochemical Properties
Authors: Korybut‐Daszkiewicz Bohdan , Taraszewska Joanna , Zięba Katarzyna , Woźniak Krzysztof , Kamiński Daniel
Published: April 2003

Two isomeric cis‐2,9‐bis(aminomethyl)‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane (1 and 2) and two 2‐aminomethyl‐2‐methyl‐1,4,8,11‐tetraazacyclotetradecane (3 and 4) cobalt(III) complexes have been prepared and characterised. During the synthesis of 2 a minor oxidation product 5 was formed. The structures of 3, 4 and 5 have been determined by X‐ray crystallography, and the UV/Vis spectra of 1−5 have been analysed. The average Co−N distances in 1 and 2 have been estimated from the correlation between the average Co−N bond lengths and position of the maximum absorption for hexaamine complexes given in literature. The electrochemical behaviour of 1−5 in neutral and acidic solutions has been studied by cyclic voltammetry. In complexes displaying electronic maxima at higher energy, cobalt(III) was reduced at more negative potentials. Small differences in the conformation of ligand between 3 and 4 explain the different behaviour of these complexes in acidic solutions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Novel P,N Ligands Derived from (R)‐ and (S)‐1‐Phenylethylamine with (2R,5R)‐2,5‐Dimethylphospholanyl Groups (DuPHAMIN) for Asymmetric Catalysis
Authors: Brauer David J. , Kottsieper Konstantin W. , Roßenbach Stefan , Stelzer Othmar
Published: April 2003

Novel P,N chelating ligands with three stereogenic centres in positions α to the donor atoms have been prepared in good yields and high enantiomeric purity by a series of reactions beginning with either (R)‐ or (S)‐1‐phenylethylamine. These isomers were first lithiated with tBuLi and converted into aminophosphanes 3a by treatment with (Et2N)2PCl. They were transformed into the enantiomeric primary phosphanes 4 by quantitative solvolysis with ethanol to give the phosphonous acid esters 3b and subsequent reduction with LiAlH4. Stepwise treatment of 4 with nBuLi and the cyclic sulfate of (S,S)‐2,5‐hexanediol gave the isomeric tertiary phosphanes (R,RR)‐5 and (S,RR)‐5. Treatment of the aminophosphane (R)‐3a with (R)‐2,2′‐binaphthol yielded the aminophosphonite (R,R)‐6 in high yields. Cationic (COD)Rh complexes of 5 were prepared by treatment with [Rh(COD)Cl]2, the PF6− salts 7a being isolated. Analogous (2,5‐norbornadiene)Rh complexes 7b were prepared similarly. The chelate nature of the P,N ligands in these salts is indicated by their NMR spectra in solution and is confirmed by the crystal structures of (R,RR)‐7a and (S,RR)‐7a. With the exception of (S,RR)‐7a, the complexes 7a and 7b are shown to catalyse the asymmetric hydrogenation of methyl acetamidocinnamate at room temperature. Differences in the catalytic activity of the complexes are related to the different dynamic behaviour detected by the 1H EXSY spectra for the COD ligands of 7a. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
CuII Ion Coordination to an Unprotected Pentadecapeptide Containing Two His Residues: Competition Between the Terminal Amino and the Side‐Chain Imidazole Nitrogen Donors
Authors: Conato Chiara , Kamysz Wojciech , Kozłowski Henryk , Łuczkowski Marek , Mackiewicz Zbigniew , Mancini Francesca , Młynarz Piotr , Remelli Maurizio , Valensin Daniela , Valensin Gianni
Published: April 2003

The complex‐formation equilibria of the pentadecapeptide TLEGTKKGHKLHLDY, the 114−128 protein fragment of SPARC, with the CuII ion have been investigated, at I = 0.1 mol·dm−3 (KNO3) and T = 298.2 K. Protonation and complex‐formation constants have been determined potentiometrically, and formation enthalpies measured by direct solution calorimetry; the complex‐formation model and species stoichiometry have been carefully checked by means of UV/Vis absorption, CD and EPR spectroscopy. The structure hypotheses of the complex species are also based on detailed study of the 1H and 13C NMR spectra of the ligand in both the absence and presence of copper ions. The involvement in complex‐formation of both the terminal amino and imidazole groups has been suggested and their specific behaviour at different pH values elucidated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Metal‐Controlled Stereoselectivity in Complex Formation: Assembly of Tetranuclear Copper(I) Complexes with Four Stereogenic Nitrogen Donor Functions in all‐(R) and all‐(S) Configurations
Authors: Schneider Jörg , Köckerling Martin , Kopitzky Rodion , Henkel Gerald
Published: April 2003

The reaction of N,N′‐dialkyl‐3,7‐diazanonane‐1,9‐dithiolate (NR2S2) ligands (R = Me, Et) with monovalent copper resulted in the formation of the chiral complexes [Cu4(NMe2S2)2] (1) and [Cu4(NEt2S2)2] (2) which were characterised by means of X‐ray diffraction and spectroscopic techniques. They contain copper atoms in both linear {S−Cu−S} fragments, which act as linkers between mononuclear [Cu(NR2S2)]− subsites, and in {CuS2N2} units within these building blocks, which can be described as incomplete coordination octahedra of unusual design. Due to favourable interplay between the spatial demands of the ligand system and the electronic requirements of the copper atom, the nitrogen donor atoms within the [Cu(NR2S2)]− metallo ligands are restricted to identical absolute configurations. The combination of two [Cu(NR2S2)]− metallo ligands with two further CuI ions to give the tetranuclear complexes 1 or 2 via S−Cu−S bridges underlies stereochemical control, resulting in optically active systems with (R,R,R,R) and (S,S,S,S) configurations. Consequently, metallo ligands in their enantiomeric forms cannot combine via S−Cu−S bridges to form optically inactive meso complexes with the (R,R,S,S) configuration. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure, and Catalytic Activity of New μ‐Oxo‐Bridged Diiron(III) Complexes
Authors: Balogh‐Hergovich Éva , Speier Gábor , Réglier Marius , Giorgi Michel , Kuzmann Ernő , Vértes Attila
Published: April 2003

The preparation and characterisation of two dinuclear iron(III) complexes with tripodal ligands 1,3‐bis(2′‐pyridylimino)isoindoline (indH) are presented. The μ‐oxo‐bridged diiron(III) complex [{FeCl(ind)}2O] (2) has been prepared by reacting FeCl3·6H2O with indH in methanol solution. Compound [{Fe(ind)(OAc)}2O] (3) was obtained from the reaction of 2 with CH3CO2Ag in THF. Both compounds were characterised by elemental analysis and UV/vis, IR, and Mössbauer spectroscopy. The X‐ray structure analysis of [Fe2O(ind)2Cl2]·THF (2·THF) revealed a distorted trigonal bipyramidal (τ = 0.88) coordination geometry around the iron(III) ion. More importantly, 2 is a good functional model for the activation of small molecules as its 5‐coordinate iron ions can easily coordinate such molecules. This is confirmed by the high catalase‐like activity of 2, transforming 87% of the excess of H2O2 into O2 in 1 min. The complexes exhibited monooxygenase‐like activity using H2O2 as the oxidant and oxidise alkanes to alcohols and ketones in acetonitrile in moderate yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Two‐Step Route to Self‐Assembly of CdS Nanotubes via Electrodeposition and Dissolution
Authors: Zhou Shao‐Min  , Feng Yi‐Si , Zhang Li‐De
Published: April 2003

Polycrystalline CdS nanotubes (CNTs) were successfully achieved by a two‐step treatment, i.e. (CdS+Cd) nanowires (electrodeposition and sulfuration process in anodic alumina membrane) ⇄ CNTs (dissolution method of removing Cd in 0.5 M HCl). Having been characterized using X‐ray diffraction and scanning electron microscopy, the nanowires, the intermediate products, contain Cd and CdS, and have uniform diameters of about 80 nm and lengths of up to 25 μm, which correspond to the pore size and thickness of the membrane used. The average inner and outer diameters of the as‐obtained CNTs are respectively 40 and 80 nm via transmission electron microscopy. Selected area electronic diffraction, X‐ray diffraction and X‐ray photoelectron energy spectroscopy investigations demonstrate that these CNTs with hexagonal wurtzite polycrystalline structure are pure and stoichiometric. The successful synthesis of these semiconductor CNTs may open up new possibilities for studies of fundamental properties and potential applications of semiconductor nanotubes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Self‐Assembly of Organodiphosphonate, Polyoxomolybdate and Diphenanthrolinecobalt(II) into Two Clusters and One Linear Polymer
Authors: Fu Rui‐Biao , Wu Xin‐Tao , Hu Sheng‐Min , Zhang Jian‐Jun , Fu Zhi‐Yong , Du Wen‐Xin , Xia Sheng‐Qing
Published: April 2003

[{Co(1,10‐phen)2}2{(Mo4O12)(O3PCH2CH2PO3)}·(H2O)] (1), [{Co(1,10‐phen)2}2{(Mo4O12)(O3PCH2CH2CH2PO3)}·(1.5H2O)] (2) and [{Co(1,10‐phen)2(H2O)2}{Co(1,10‐phen)2(H2O)}{(Mo5O15)(O3PCH2CH2CH2CH2PO3)}·(6H2O)] (3) were synthesized by self‐assembly of H2O3P(CH2)nPO3H2 (n = 2−4), polyoxomolybdate and [Co(1,10‐phen)2]2+ (1,10‐phen = 1,10‐phenanthroline) under hydrothermal conditions. Compounds 1 and 2 are novel heterometallic hexanuclear clusters, while compound 3 is a new linear polymer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ultrasonically Enhanced Voltammetric Analysis and Applications: An Overview
Authors: Banks Craig E. , Compton Richard G.
Published: April 2003

Ultrasonically enhanced voltammetric measurements have been successfully applied for the detection of a wide range of trace metals. These are reviewed and the beneficial effects of power ultrasound applied to electroanalysis highlighted, most notably the possibility for quantitative analysis in otherwise highly passivating media, where classical electrochemical techniques often fail.
NADH Oxidation Using Carbonaceous Electrodes Modified with Dibenzo‐Dithia‐Diazapentacene
Authors: Munteanu Florentina‐Daniela , Dicu Delia , Popescu Ionel Catalin , Gorton Lo
Published: April 2003

The electrochemical and the electrocatalytic behavior for NADH oxidation of a newly synthesized phenothiazine derivative, 16H,18H‐dibenzo[c,1]‐7,9‐dithia‐16,18‐diazapentacene (DDDP), adsorbed on solid spectrographic graphite and on graphite powder or on zirconium phosphate (ZP), both entrapped in carbon paste, were compared. Experiments using cyclic voltammetry and a rotating disk electrode, performed in different experimental conditions (various pH values and NADH concentrations), showed that i) in the pH range between 4 and 8, the E°' value for DDDP adsorbed on ZP becomes pH independent; ii) in contrast to other redox mediators, adsorption of DDDP on ZP induced a significant negative shift of the E°' value; iii) the reaction rate for electrocatalytic oxidation of NADH is markedly increased by adsorbing the mediator on ZP, being further improved by the presence of Ca2+ ions in the solution.
Electrocatalytic Properties of Electropolymerized Ni(II)curcumin Complex
Authors: Ciszewski Aleksander , Milczarek Grzegorz , Lewandowska Beata , Krutowski Krzysztof
Published: April 2003

The voltammetric behavior in alkaline solution of a nickel‐based chemically modified electrode (poly‐Ni(II)curcumin) prepared by oxidative electropolymerization of nickel‐curcumin complex for electrooxidation of aliphatic alcohols was investigated by cyclic voltammetry and rotating disk technique (curcumin=1,7‐bis[4‐hydroxy‐3‐methoxyphenyl]‐1,6‐heptadiene‐3,5‐dione). The dependence of the oxidation current on the alcohol concentration and on the number of redox centers Ni(II)/Ni(III) is discussed. From the fact that the oxidation current increases with the increase of film thickness it is evident that the electrocatalytic reaction occurs inside the polymer film. The system examined is a typical example of a redox polymer with 3D properties. It is also concluded that the reaction mechanism of alcohol oxidation is the case, according to the concept of Andrieux and Saveant, where the cross‐exchange reaction is the limiting step. The mechanism of modifying the film formation has also been discussed.
Designing Potentiometric Sensor Materials for the Determination of Organic Ionizable Substances in HPLC
Authors: Nagels Luc J. , Bazylak Grzegorz , Zielinska Danuta
Published: April 2003

This article provides a model to explain the response of liquid membrane type potentiometric electrodes towards organic ions in HPLC systems. The model is a synthesis of data from 7 recent articles from our group on the determination of several classes of compounds (organic acids, amines, beta‐blockers, clenbuterol, mucolytic drugs and aminoalcohols) with potentiometric detection in HPLC. The presented model uses the difference in chemical potential of the analyte ion in the eluent and in the membrane phase as the sensitivity determining factor. Methods used to estimate this difference in chemical potential are compared. For liquid membrane coatings containing no selectively interacting (complex forming) ionophores, this difference could be estimated from calculated log P (lipophilicity) and P (polarizability) values for the analyte ions. If complex forming agents are present, the extra interaction of the analyte ion with the complex forming agent can be estimated via a solvation parameter model. In the latter case, molecular modeling may also be useful.
Studies on Self‐Assembled Alkanethiol Monolayers Formed at Applied Potential on Polycrystalline Gold Electrodes
Authors: Brett Christopher M. A. , Kresak Slavoj , Hianik Tibor , Oliveira Brett Ana Maria
Published: April 2003

1‐Dodecanethiol assembly on polycrystalline gold electrodes at fixed positive potentials has been investigated by chronoamperometry and electrochemical quartz crystal microbalance and the films formed characterized by cyclic voltammetry and electrochemical impedance spectroscopy. It was found that 1‐dodecanethiol adsorption on gold is enhanced by application of positive potentials to the electrode surface and that adsorption proceeds faster than in the case of open circuit deposition. Compact defect‐free monolayers of capacitance values of 1.1–1.6 μF cm−2 are produced in time intervals as short as 100 s, with no roughness, as demonstrated for the first time by electrochemical impedance analysis. Control of surface potential during alkanethiol assembly appears to improve monolayer quality and to allow for shorter assembly periods. Monolayers can be removed by cycling in alkaline solution or in dilute sulfuric acid. These results are important for the fast construction of defect‐free bilayers.
Supramolecular Derivatives of 9,10‐Anthraquinone. Electrochemistry at Regular‐ and Low Ionic Strength and Complexing Properties
Authors: Zon Agnieszka , Palys Marcin , Stojek Zbigniew , Sulowska Hanna , Ossowski Tadeusz
Published: April 2003

Three newly synthesized polyanthraquinone derivatives: 7,13‐bis(9,10‐dioxo‐1‐anthryl)‐1,4,10‐trioxa‐7,13‐diazacyclopentadecane, (AQ)A215C5, 7,16‐bis(9,10‐dioxo‐1‐anthryl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane, (AQ)A218C6, and tris[(9,10‐diokso‐1‐antryl)‐aminoethyl]amine, (AQNet)3N, were examined by cyclic and normal pulse voltammetry. All anthraquinone groups in these compounds were electroactive and formed the radicals and dianions similarly to simple anthraquinone. The differences between the voltammograms obtained in the absence and presence of supporting electrolyte are discussed, and the diffusion coefficients of the compounds and the rates of the chemical reactions following the first reduction step were evaluated. (AQNet)3N appears to be a good model compound for multi electron transfers in aprotic solvents. It offers two consecutive nearly reversible 3‐electron redox systems: 0/−3 and −3/−6. The interactions of the radicals and dianions of the above compounds with alkali metal cations were examined.
Genetic differentiation and subspecies development of the giant panda as revealed by DNA fingerprinting
Authors: Wan Qiu‐Hong , Fang Sheng‐Guo , Wu Hua , Fujihara Tsutomu
Published: April 2003

Over the last 100 years giant pandas (Ailuropoda melanoleuca) have been separated into six completely isolated mountain ranges. DNA fingerprinting revealed different differentiation patterns in giant pandas, including early‐stage, late‐stage, recent divergence and recent genetic depression. A separation around 10 000 years ago resulted in highly significant differences in DNA fingerprints and morphological characteristics between Qinling and Sichuan populations. Supported by morphological differences, the genetic data were used to classify the Qinling population as a new subspecies, A. m. qinlingensis, while the Sichuan populations were classified into the original subspecies, A. m. melanoleuca. Thus, the Qinling population deserves management as a separate unit. In the Sichuan populations, two management units were defined, including Qionglai‐Minshan and Daxiangling‐Xiaoxiangling‐Liangshan. Our data suggest urgent measures are needed to establish green corridors between subpopulations in each mountain range to increase gene flow and genetic variation to ensure long‐term survival.
Capillary electrophoresis with end‐column amperometric detection of urinary 8‐hydroxy‐2'‐deoxyguanosine
Authors: Mei Su‐Rong , Yao Qing‐Hong , Cai Ling‐suang , Xing Jun , Xu Guo‐Wang , Wu Cai‐ying
Published: April 2003

Urinary 8‐hydroxy‐2'‐deoxyguanosine (8OHdG) is an excellent marker of oxidative DNA damage. Until now, urinary 8OHdG has been measured by high‐performance liquid chromatography with electrochemical detection. A simple and sensitive method for the analysis of urinary 8OHdG by capillary electrophoresis with end‐column amperometric detection has been developed in our laboratory. A single‐step solid‐phase extraction procedure was optimized and used for extracting 8OHdG from human urine. To improve the sensitivity of this method, a new focusing technique based on a dynamic pH junction was used. The limit of detection was 20 nM (signal‐to‐noise ratio S/N = 3), the linear range was 50 nM–10 μM, and the correlation coefficient was better than 0.999. The relative standard deviation (RSD) was found to be 0.57% for migration time, and 4.79% for peak current. To show the usefulness of the method, the urinary concentration of 8OHdG in nine healthy persons and ten cancer patients was determined. The urinary concentration of 8OHdG in cancer patients was significantly higher than that in healthy persons.
Determination of enantiomeric purity of a novel COX‐2 anti‐inflammatory drug by capillary electrophoresis using single and dual cyclodextrin systems
Authors: Pérez‐Maseda Carlos , Calvet Carme , Cuberes Rosa , Frigola Jordi
Published: April 2003

E‐6087 is the most advanced compound among the cyclooxygenase‐2 (COX‐2) inhibitor drugs developed in our company. Its activity is mainly associated with the S(−)‐enantiomer (E‐6232), whereas the R(−)‐enantiomer (E‐6231) becomes an impurity whose content should be determined. Five main impurities and degradation products of E‐6232 have been found (E‐6144, E‐6024, E‐6072, E‐6397 and E‐6132), and some of them co‐elute with the distomer when using a chiral high‐performance liquid chromatography (HPLC) method. Consequently, we have optimized the separation of all the impurities from the two enantiomers of E‐6087 by capillary electrophoresis (CE), in order to use the method for the enantiomeric purity determination of E‐6232. The effect of the methanol (MeOH) content in the background electrolyte (BGE), the sulfobutyl ether‐β‐cyclodextrin (SBE‐β‐CD) and heptakis‐(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DM‐β‐CD) concentration, and the capillary temperature have been studied. Separation of all compounds could be achieved in different systems, either in a single CD‐system (with SBE‐β‐CD) or in a dual CD‐system (with DM‐β‐CD as a neutral CD). By using the dual CD system a limit of detection (LOD) and a limit of quantitation (LOQ) of 0.03% and 0.1% of distomer, respectively, were achieved*.
Capillary electrophoresis separation of high molecular weight glutenin subunits in bread wheat (Triticum aestivum L.) and related species with phosphate‐based buffers
Authors: Yan Yueming , Yu Jianzhong , Jiang Yi , Hu Yingkao , Cai Minhua , Hsam Sai L. K. , Zeller Friedrich J.
Published: April 2003

This study focused on optimizing phosphate‐based buffers and other capillary electrophoresis (CE) parameters for separating and characterizing high molecular weight glutenin subunits (HMW‐GS) in bread wheat (Triticum aestivum L., AABBDD, 2n = 6x = 42), emmer (Triticum dicoccum, AABB, 2n = 4x = 28) and Aegilops tauschii (DD, 2n = 2x = 14). The fast and high‐resolution separation of HMW‐GS was achieved using 0.1 M phosphate‐glycine buffer (pH 2.5, containing 20% acetonitrile and 0.05% hydroxypropylmethylcellulose) at 12.5 kV and 40°C with 25 μm inside diameter (ID)×27 cm uncoated fused‐silica capillary. In general, one sample separation can be analyzed in 15 min. The good run‐to‐run repeatable separation of HMW‐GS could be obtained with a relative standard deviation of less than 1% when capillaries were rinsed with 1 M phosphoric acid for 2 min, followed by separation buffer for 2 min after each separation. The HMW‐GS from some bread wheat cultivars as well as tetraploid and diploid accessions was separated by the CE method described above, and all subunits detected were well characterized and readily identified. Some HMW‐GS showed reversed mobilities and elution order compared to the methods of sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and SDS‐CE. Particularly, most of the HMW‐GS analyzed with the CE buffer used were separated into multiple peaks, generally a high peak plus a minor peak. CE appears to be capable of separating and characterizing HMW‐GS with fast and high‐resolution features, therefore it is expected to be useful for specific germplasm screening and desirable HMW‐GS identification in wheat quality improvement.
ADAM‐10 and ADAM‐17 in the inflamed human CNS
Authors: Kieseier Bernd C. , Pischel Heidrun , Neuen‐Jacob Eva , Tourtellotte Wallace W. , Hartung Hans‐Peter
Published: April 2003

Inflammatory demyelinating disorders of the CNS, such as multiple sclerosis (MS), are mediated, at least in part, by various cytokines and proteases. In the present study, we investigated the expression of A disintegrin and metalloproteinase (ADAM)‐17, an important sheddase for various proteins, including tumor necrosis factor‐α (TNF‐α), and the p75‐ and p55‐TNF receptors, as well as ADAM‐10, a protease implicated in myelin degradation, in post mortem CNS tissue samples from patients with MS, and normal brain tissue (as control) by immunohistochemistry. ADAM‐10 was found to be expressed by astrocytes in all MS and control sections studied; however, in some MS sections, perivascular macrophages were determined as an additional cellular source as well. ADAM‐17 could be observed exclusively in acute and chronic active MS plaques and localized to invading T lymphocytes. The staining pattern of ADAM‐17 in MS plaques was mirrored in distribution and extent by the pattern obtained with an antibody against the p75–TNF‐receptor (TNFR‐2), whereas TNF‐α was found to be expressed primarily by perivascular macrophages. In studying cerebrospinal fluid (CSF) samples from MS patients, we were able to detect increased protein levels of ADAM‐17 as compared with noninflammatory controls. In addition, increased levels of soluble TNFR‐2 could be measured, suggestive of an active shedding process mediated by ADAM‐17. The stimulation of peripheral blood mononuclear cells (PBMC) obtained from MS patients and healthy individuals corroborated these findings by revealing expression of ADAM‐17 by T lymphocytes and ADAM‐10 by macrophages in vitro. Our results indicate that ADAM‐10 is expressed constitutively by astrocytes in the normal and inflamed human CNS. In contrast, under inflammatory conditions, ADAM‐10, expressed by perivascular macrophages, and ADAM‐17, expressed by invading T cells, may actively contribute to the pathogenesis of inflammatory disorders of the CNS. GLIA 42:398–405, 2003. © 2003 Wiley‐Liss, Inc.
Expression of complement messenger RNAs and proteins by human oligodendroglial cells
Authors: Hosokawa Masato , Klegeris Andis , Maguire John , McGeer Patrick L.
Published: April 2003

Neurons, astrocytes, microglia, and endothelial cells are capable of synthesizing most, if not all, of the complement proteins. Little is known, however, about the capacity of oligodendroglial cells to generate complement components. This study evaluated expression of complement mRNAs and their protein products by human oligodendrocytes. Cells were isolated and cultured from white matter of seven adult cases that had undergone surgical temporal lobe resection for epilepsy. Oligodendroglial cultures were characterized by the expression of such cell type‐specific mRNAs as myelin proteolipid protein (PLP), oligodendrocyte‐specific protein (OSP), and 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPase) and were further characterized by immunostaining for such differentiation markers as myelin basic protein (MBP), PLP, CNPase, and O4. RT‐PCR analysis showed that the oligodendroglial cells expressed detectable levels of complement mRNAs for the C1q B‐chain, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 γ subunit, and C9. Immunostaining was positive for C1q, C1s, C2, C3, C4, C5, C6, C7, C8, and C9. Double immunostaining for the oligodendrocyte marker O4 and the complement protein C3 demonstrated that all O4‐positive cells were also positive for C3, indicating constitutive C3 expression. These results indicate that oligodendroglial cells may be a source of complement proteins in human brain and thus could contribute to the pathogenesis of several neurodegenerative and inflammatory diseases of the CNS, such as Alzheimer's disease, multiple sclerosis, and progressive supranuclear palsy, where complement‐activated oligodendrocytes are abundant. GLIA 42:417–423, 2003. © 2003 Wiley‐Liss, Inc.
Pressure inside Small Cavities: A Possible Factor in Enzyme Catalysis and Selectivity
Authors: Saunders Martin
Published: April 2003

There are many different examples where atoms or molecules are found in cavities within larger (cage) molecules. The term host–guest chemistry has been used to describe this situation. This paper considers the possibility that pressure within the cavities can be measured or calculated in several possible ways. The various values for pressure for different systems can serve to compare them. It is suggested that pressure might be related to the rate of escape of the contents through an opening in the cage wall and to the equilibrium between inside and outside. Furthermore, in the case of substrates within enzyme active sites, it is suggested that the pressure is anisotropic. Pressure localized along certain directions may play an important role in the catalytic function of the enzyme.
Mapping the Geometry of Metal Three‐Coordination Using Crystal Structure Data: Reaction Pathway for Ligand Addition to Linear HgII Species
Authors: Allen Frank H. , Mondal Raju , Pitchford Nigel A. , Howard Judith A. K.
Published: April 2003

Symmetry‐modified principal‐component analysis has been used to visualise the geometrical distortions of three‐coordinate metal centres observed in crystal structures retrieved from the Cambridge Structural Database. It is shown that compounds of Cu, Ag, Hg, Zn, and Au dominate the dataset, and exhibit distortions away from the trigonal planar archetype towards a) T‐shaped and b) Y‐shaped geometries. A small number of compounds, principally of Cu and Ag, also show distortions towards trigonal pyramidal geometries. The interconversions from Y‐shaped geometries, through the trigonal planar form to T‐shaped geometries are clearly mapped by the PC analysis. For HgII complexes, it is possible to interpret the transition from T‐shaped geometries to the trigonal planar form in terms of a reaction pathway for ligand addition to linear L1HgIIL2 species.
Synthesis and Some Biochemical Properties of a Novel 5,6,7,8‐Tetrahydropyrimido[4,5‐c]pyridazine Nucleoside
Authors: Loakes David , Brown Daniel M. , Salisbury Stephen A. , McDougall Mark G. , Neagu Constantin , Nampalli Satyam , Kumar Shiv
Published: April 2003

A novel nucleoside analogue is described based on the pyridazine ring system. The nucleoside was successfully incorporated into DNA via both its phosphoramidite and 5′‐triphosphate derivatives. Enzymatically, the analogue behaves essentially as thymidine: it is a good substrate for the DNA polymerases Taq and exonuclease‐free Klenow fragment, leading to full‐length products when present in either the primer or template strands. In hybridisation studies, the nucleoside displays ambiguous base‐pairing properties, including universal base properties.
1,2,4,5‐Tetrazines vs. Carboxylic Acid Dimers: Molecular Chemistry vs. Supramolecular Chemistry
Authors: Infantes Lourdes , Mahon Mary F. , Male Louise , Raithby Paul R. , Teat Simon J. , Sauer Jürgen , Jagerovic Nadine , Elguero José , Motherwell Sam
Published: April 2003

The structures of six new tetrazines have been determined and their molecular packing has been compared to the supermolecular architecture observed in related carboxylic acid dimers. In the tetrazines, covalent NN bonds are considered to replace the intermolecular OH⋅⋅⋅O hydrogen bonds of the carboxylic acids. In the systems investigated, it is apparent that, in the majority of cases, the covalent six‐membered ring of the tetrazine is an appropriate replacement for the carboxylic acid synthon. This apparent interplay between molecular and supramolecular units may have applications in the crystal engineering of new materials.
Crystal Structure of an EMAP‐II‐Like Cytokine Released from a Human tRNA Synthetase
Authors: Yang Xiang‐Lei , Liu Jianming , Skene Robert J. , McRee Duncan E. , Schimmel Paul
Published: April 2003

Aminoacyl‐tRNA synthetases catalyze the first step of protein synthesis by aminoacylation of tRNAs. Remarkably, biological fragments of two human enzymes – tyrosyl‐tRNA synthetase (TyrRS) and tryptophanyl‐tRNA synthetase – are active cytokines produced by proteolysis or alternative splicing. One is a C‐terminal fragment of TyrRS (C‐TyrRS) that has potent activity for chemotaxis of leukocytes and monocytes and for stimulating production of other cytokines. Significantly, the cytokine activity of C‐TyrRS is absent in the context of the full‐length native protein. Unknown is the mechanism by which domain‐release from the dimeric native protein activates the cytokine. Here, the crystal structure of C‐TyrRS is presented at 2.2 Å resolution. This structure is similar to that of endothelial monocyte‐activating protein II (EMAP‐II), with critical residues of a heptapeptide element important for chemotaxis activity exposed on the first strand of a β‐barrel of the monomeric unit. In contrast, the same residues of C‐TyrRS are buried in an operational model for native TyrRS. Importantly, C‐TyrRS is shown here to be monomeric when released from dimeric native TyrRS. Further analysis suggests that the critical residues are exposed when tRNA is bound. Thus, tRNA binding to native TyrRS may be an additional or alternative way to activate cytokine signaling.
Comparing Intrinsic Reactivities of the First‐ and Second‐Generation Ruthenium Metathesis Catalysts in the Gas Phase
Authors: Adlhart Christian , Chen Peter
Published: April 2003

An experimental comparison of the gas‐phase reactivity of the 14‐electron reactive intermediates produced by phosphine dissociation from the first‐ and second‐generation ruthenium metathesis catalysts, (L)Cl2RuCHR (L=PCy3 or NHC), supports Grubbs's contention that the second‐generation catalysts show hundred‐fold higher phenomenological activity despite a slower phosphine dissociation because of a much more‐favorable partitioning of the 14‐electron active species towards product‐forming steps. The gas‐phase study finds, in ring‐opening metathesis of norbornene as well as acyclic metathesis of ethyl vinyl ether, that the first‐generation systems display evidence for a higher barrier above that for phosphine dissociation; the second‐generation systems, on the other hand, behave as if there is no significantly higher barrier.