bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictors of operative morbidity and mortality in gastric cancer surgery
Authors: Park D J , Lee H-J , Kim H-H , Yang H-K , Lee K U , Choe K J
Published: June 2005

Background

The aim of this study was to identify factors that predict morbidity and mortality in gastric cancer surgery.

Methods

Data on 719 consecutive patients who underwent operations for gastric cancer at Seoul National University Hospital between January and December 2002 were reviewed.

Results

Overall morbidity and mortality rates were 17·4 per cent (125 patients) and 0·6 per cent (four patients) respectively, and the rates of surgical and non-surgical complications were 14·7 per cent (106 patients) and 3·3 per cent (24 patients). Morbidity rates were higher in patients aged over 50 years (odds ratio (OR) 1·04 (95 per cent confidence interval (c.i.) 1·02 to 1·06)), when the gastric tumour was resected with another organ (36 per cent for combined resection versus 15·4 per cent for gastrectomy only; OR 3·25 (95 per cent c.i. 1·76 to 6·03)) and when gastrojejunostomy was used for reconstruction after subtotal gastrectomy (17·0 per cent for Billroth II versus 9·5 per cent for Billroth I; OR 2·00 (95 per cent c.i. 1·05 to 3·79)). Only three patients (2·8 per cent) with a surgical complication underwent reoperation, two for adhesive obstruction and one for intra-abdominal bleeding.

Conclusion

Age, combined resection and Billroth II reconstruction after radical subtotal gastrectomy were independently associated with the development of complications after gastric cancer surgery.
Hydroxymethylglutaryl co-enzyme A reductase inhibition attenuates endotoxin-mediated inflammatory responses
Authors: Joyce M , Casey R , Gang C , Winter D , Kelly C J , Bouchier-Hayes D J
Published: June 2005

Background

The aim of this study was to investigate whether inhibition of hydroxymethylglutaryl co-enzyme A reductase attenuates leucocyte–endothelial cell interactions and alters expression of endothelial constitutive nitric oxide synthase (ecNOS) and inducible nitric oxide synthase (iNOS) following exposure to endotoxin.

Methods

Male Sprague–Dawley rats were randomized into control, lipopolysaccharide (LPS) and pravastatin + LPS groups (seven per group). Pravastatin sodium was gavaged at 0·4 mg per kg per day for 5 days, after which LPS 15 mg/kg was administered via the jugular vein. Intravital microscopy was used to determine leucocyte–endothelial cell interactions.

Results

Following the administration of LPS there was a significant reduction in leucocyte rolling velocity at 10 min (mean(s.e.m.) 69(3) versus 102(6) per cent of baseline value; P = 0·041), an increase in the number of adherent leucocytes at 10 min (4·5(0·5) versus 2·8(0·3) per 100 µm; P = 0·044) and an increase in the number of leucocytes undergoing transendothelial migration at 30 min (4·2(0·4) versus 1·7(0·4) per field; P = 0·008) compared with controls. Pretreatment with pravastatin significantly attenuated LPS-induced leucocyte–endothelial cell interactions (rolling velocity 89(6) per cent at 10 min, P = 0·038; adherent leucocytes 3·0(0·5) per 100 µm at 10 min, P = 0·038; migrating leucocytes 1·9(0·5) per field at 30 min, P = 0·001). This endothelial protection was associated with maintenance of ecNOS and reduced iNOS expression within mesenteric tissues.

Conclusion

These data show that pravastatin produces anti-inflammatory effects in response to injurious stimuli by attenuation of leucocyte–endothelial cell interactions.
Predictors of operative death after oesophagectomy for carcinoma
Authors: Abunasra H , Lewis S , Beggs L , Duffy J , Beggs D , Morgan E
Published: June 2005

Background

Oesophagectomy for carcinoma provides a chance of cure but carries significant risk. This study defined risk factors for death after oesophageal resection for malignant disease.

Methods

Between 1990 and 2003, 773 oesophagectomies for oesophageal cancer were performed. Continuous variables were categorized into quartiles for analysis. Predictors of operative mortality were identified by univariate and multiple logistic regression analysis.

Results

The operative mortality rate was 4·8 per cent (37 of 773). In univariate analysis, advanced age, reduced forced expiratory volume in 1 s (FEV1), reduced forced vital capacity, presence of diabetes and tumour located in the upper third of the oesophagus were associated with a higher mortality rate. Multivariate analysis identified age (highest relative to lowest quartile, odds ratio (OR) 4·87 (95 per cent confidence interval (c.i.) 1·35 to 17·55); P = 0·009), tumour position (upper third relative to other locations, OR 4·23 (95 per cent c.i. 1·06 to 16·86); P = 0·041) and FEV1 (lowest relative to highest quartile, OR 4·72 (95 per cent c.i. 1·01 to 21·99); P = 0·018) as independent predictors of death.

Conclusion

Advanced age, impaired preoperative respiratory function and a tumour high in the oesophagus are associated with a significantly increased risk of death after oesophagectomy for carcinoma.
Simultaneous quantification of six ephedrines in a Mahwang preparation and in urine by high‐performance liquid chromatography
Authors: Chan Kuei Hui , Pan Ryh‐Nan , Hsu Mei‐Chich
Published: June 2005

A rapid and reliable high‐performance liquid chromatographic method was developed and validated for the simultaneous determination of norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME) and methylpseudoephedrine (MPE) in both a Mahwang traditional Chinese medicine (TCM) preparation and in urine using α‐ethylbenzylamine as the internal standard. The method uses a Spherisorb C18 column for an isocratic elution in a tetraethylammoniumphosphate‐methanol mobile phase at a wavelength of 206 nm. The limits of detection of NE, NPE, E, PE, ME and MPE in sample solutions ranged from 0.1 to 0.3 µg[sol ]mL at a signal‐to‐noise ratio of 3. The within‐day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.2 and 1.4% for each analyte. The between‐day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.8 and 5.9% for each analyte. The between‐day accuracy as determined from the Mahwang TCM preparation and urine samples was below 2.2 and 6.8% for each analyte. The recoveries for six compounds, obtained with compounds spiked into the Mahwang TCM preparation and urine, were found to be more than 93.6%. This method can be successfully applied to doping and excretion rate studies. Copyright © 2005 John Wiley & Sons, Ltd.
Kinetic and NMR Spectroscopic Studies of Chiral Mixed Sodium/Lithium Amides Used for the Deprotonation of Cyclohexene Oxide
Authors: Sott Richard , Granander Johan , Williamson Carl , Hilmersson Göran
Published: June 2005

The mixed‐metal complex formed from n‐butylsodium, n‐butyllithium, and a chiral amino ether has been studied by NMR spectroscopy. Three different mixed‐metal amides were used as chiral bases for the deprotonation of cyclohexene oxide. The selectivity and initial rate of reaction were compared for sodium–amido ethers, lithium–amido ethers, and mixtures of sodium and lithiumamido ethers in diethyl ether and tetrahydrofuran, respectively. The mixed sodium/lithium amides are more reactive than the single sodium and lithium amides, whereas the stereoselectivities are higher when lithium amides are used. The alkali‐metal/γ‐amido ethers exhibit both higher initial reaction rates and stereoselectivities than their β‐amido ether analogues. NMR spectroscopic studies of mixtures of n‐butylsodium (nBuNa), n‐butyllithium (nBuLi), and the γ‐amino ethers in diethyl ether show the exclusive formation of dimeric mixed‐metal amides. In diethyl ether, the lithium atom of the mixed‐metal amide is internally coordinated and the sodium atom is exposed to solvent; however, in tetrahydrofuran, both metals are internally coordinated.
Molecular modelling of the inclusion complexes between β‐cyclodextrin and (R)/(S)‐methylphenobarbitone and its application to HPLC
Authors: Durham David G. , Liang Hongxi
Published: May 2005

Molecular modelling of β‐cyclodextrin and optimisation of its potential energy suggests that a favoured conformation is that distorted from a symmetrical torus. The inclusion of water molecules into the torus cavity simulates the increased stability in an aqueous solvent. Complexes of β‐cyclodextrin with (R)‐ and (S)‐enantiomers of methylphenobarbitone have been modelled and energetically optimised by the application of molecular mechanics. The simulations suggests that the guest molecules adopt an orientation in which the phenyl ring is projected into the torus cavity, with in each case the plane of the ring parallel to a longer axis of the distorted torus and slightly displaced from the axis through the torus cavity. It is suggested that the asymmetry in the macrocyclic ring contributes to chiral recognition as a result of additional discriminatory binding to the barbiturate ring residue of each enantiomer, which occupy different 3D geometries. The enantiomers form complexes of different minimum potential energies. The resulting difference in complex stability can be related to the behaviour of β‐cyclodextrin, as a mobile phase additive in reverse‐phase HPLC to effect chiral separation of rac‐medthylphenobarbitone during chromatography. © 1994 Wiley‐Liss, Inc.
Are Conical Intersections Responsible for the Ultrafast Processes of Adenine, Protonated Adenine, and the Corresponding Nucleosides?
Authors: Brøndsted Nielsen Steen , Sølling Theis I.
Published: June 2005

Excited‐state potential energy surfaces of adenine, protonated adenine, and their N9‐methylated analogs are explored by means of a complete active space (CAS) and time‐dependent density functional theory (TD‐DFT) study to understand the dynamics associated with internal conversion. After photoexcitation of the ground‐state molecules to the S1 state, the nuclear motions that are responsible for taking the wavepacket out of the Franck–Condon region are either an HN9/CN9 stretch or a ring‐puckering motion that leads to pyramidalization. These motions lead to accessible conical intersections with the ground‐state surface. The results are used to successfully interpret previous measurements on the photodissociation of adenosine 5′‐monophosphate nucleotide anions and cations, where the latter react in a highly nonstatistical manner.
On the Redox Chemistry of GeI Bromide
Authors: Schnepf Andreas
Published: June 2005

First results on the redox chemistry of GeI bromide are reported herein. During the attempt to solubilize GeIBr, which is synthesized in preparative scale using a co‐condensation technique of the high‐temperature molecule GeIBr, a redox reaction with the solvent acetone occurs. During this unexpected redox reaction GeI is oxidized to GeIV and acetone is reductively coupled to 1,1‐dimethyl‐3‐oxobutan‐1‐yl. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
In Situ XAS and XRD Studies on the Structural Evolution of Ammonium Paratungstate During Thermal Decomposition
Authors: Kirilenko Olga , Girgsdies Frank , Jentoft Rolf E. , Ressler Thorsten
Published: June 2005

The bulk structural evolution during the decomposition of ammonium paratungstate (APT) under various oxidizing and reducing gases was elucidated by the complementary techniques, in situ XAS, in situ XRD, and TG/DSC, combined with mass spectrometry. In the temperature range from 300 to 650 K, the decomposition of APT proceeds nearly independently of the gas employed. At higher temperatures, an oxidizing gas results in the formation of crystalline triclinic WO3 as the majority phase at 773 K, while mildly reducing gases (propene, propene and oxygen, and helium) result in the formation of partially reduced and highly disordered tungsten bronzes. No further reduction is observed under propene or helium, and this indicates a strongly hindered oxygen mobility in the tungsten oxide lattice in the temperature range employed. The decomposition of APT under hydrogen results in the formation of WO2 and, eventually, tungsten metal. During the thermal treatment of APT, major changes occur at ca. 500 K where a complete structural rearrangement takes place that results in the destruction of the polyoxotungstate ion of APT and the formation of a tungsten oxide bronze. The rather low temperature for the formation of a three‐dimensional lattice compared to the thermal treatment of common polyoxomolybdate precursors indicates the lower stability of the precursor and intermediates as ligands are removed. For tungsten to act as a potential structural or electronic promoter in molybdenum oxide based catalysts, tungsten needs to be incorporated in regular molybdenum oxide structures already at a very early stage of the catalyst preparation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A New Series of Homologous Cluster Complexes [Mo3(M'EPh3)Q4Cl4(H2O)5] (M' = Ni, Pd; E = P, As, Sb; Q = S, Se)
Authors: Sokolov Maxim N. , Chubarova Elena V. , Hernandez‐Molina Rita , Clausén Maria , Naumov Dmitry Yu. , Vicent Cristian , Llusar Rosa , Fedin Vladimir P.
Published: June 2005

Cluster aqua complexes [Mo3(M'Cl)S4(H2O)9]3+ (M' = Ni, Pd) react with EPh3 (E = P, As, Sb) in HCl/CH3OH to give neutral [Mo3(M'EPh3)S4Cl4(H2O)5] (M' = Pd, E = P (1), E = As (2), E = Sb (3); M' = Ni, E = P (4), E = As (5); E = Sb (6). [Mo3(PdPPh3)Se4Cl4(H2O)5] (7) was also obtained. X‐ray crystal structures were determined for 3, 4 and 5. The role of supramolecular interactions in crystal packing is discussed. ESI‐MS spectra were also studied and were used to follow the coordination of the solvent molecules at Mo sites and to assess relative strength of bonding in the clusters. Thermal properties were studied for 4 and 5. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Mono‐ and Bilayered Lead(II)–bpno Polymers with Unusual Low Energy Emission Properties (bpno = 4,4'‐Bipyridine N,N'‐Dioxide)
Authors: Xu Yanqing , Yuan Daqiang , Han Lei , Ma En , Wu Mingyan , Lin Zhengzhong , Hong Maochun
Published: June 2005

Reaction of 4,4'‐bipyridine N,N'‐dioxide (bpno) and lead(II) nitrate with or without dicyanamido ions (dca) in aqueous solution yielded polymeric complexes {Pb2(bpno)4(dca)2(NO3)2Pb2(bpno)4(NO3)4·5H2O}n (1) and {Pb(bpno)(NO3)2·H2O}n (2), respectively. The single‐crystal X‐ray analyses show that the structures of both complexes consist of dinuclear PbII units which are bridged through bpno ligands in novel modes to extend their topologies. Compound 1 exhibits a bilayered rhombus grid, while 2 displays a monolayered rhombus grid. The different excitations of solid samples of 1 and 2, at room temperature, produced intense emission bands which are almost the same in appearance with peak maxima at 616 nm and 617 nm, respectively. Both low‐energy emissions were determined to be phosphorescence by their long decay lifetime at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis and Structure of a 2,4‐Unsubstituted cis/trans‐1,3‐Disilacyclobutane by Dehydrofluorination of a Highly Hindered Fluorosilane
Authors: Pietschnig Rudolf , Spirk Stefan , Belaj Ferdinand , Merz Klaus
Published: June 2005

The preparation, molecular structure, and metalation behavior of a sterically highly congested fluorosilane (tBuTipMeSiF) are described. This silane is subjected to dehydrofluorination under thermally mild conditions. A C‐unsubstituted transient intermediate — either the silene or the corresponding silenoid — is generated in a metalation/elimination sequence at low temperatures, and this intermediate dimerizes to give the corresponding 1,3‐disilacyclobutane exclusively, even in the presence of a trapping agent. The significant steric hindrance in the starting fluorosilane and the final 1,3‐disilacyclobutane is corroborated by their crystal structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Four Novel 3D Copper(II) Coordination Polymers with Different Topologies
Authors: Yang Jin , Ma Jian‐Fang , Liu Ying‐Ying , Li Shun‐Li , Zheng Guo‐Li
Published: June 2005

A series of CuII coordination polymers with different topologies, namely [CuL(L1)]·2 H2O (1), [CuL1.5(L2)]·3 H2O (2), [CuL(L3)]·3 H2O (3) and [Cu2L2.5(L4)(H2O)]·10 H2O (4) [L = 1,1'‐(1,4‐butanediyl)bis(imidazole), H2L1 = fumaric acid, H2L2 = 1,1'‐ferrocenedicarboxylic acid, H2L3 = succinic acid, and H4L4 = pyromellitic acid], are presented. Different polymeric frameworks are obtained by varying the polycarboxylate anions. These include the threefold interpenetrated diamond structure of 1, the rare twofold interpenetrated 4664 network of 2, and two planar four‐connected networks of 3 and 4, which display an unusual Archimedean‐type (658)(6482) net containing two different types of nodes and a (5648)(526282)2(68 410)(5462) net containing four different types of nodes, respectively. Thermogravimetric analysis (TGA) curves of 1, 2, 3, and 4 exhibit three similar weight‐loss stages. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation and Crystal Structures of Benzoylhydrazido‐ and‐diazenidorhenium Complexes with N,O‐Ligands and Their Catalytic Activity Towards Peroxidative Oxidation of Cycloalkanes
Authors: Kirillov Alexander M. , Haukka Matti , Guedes da Silva M. Fátima C. , Pombeiro Armando J. L.
Published: June 2005

The η2‐(benzoylhydrazido)rhenium(V) complex [Re{(OCH2CH2)2N(CH2CH2OH)}{N=NC(O)Ph}(PPh3)] (2) and the η1‐(benzoyldiazenido)rhenium(III) compounds [ReCl{N(CH2COO)(CH2CH2OH)(CH2CH2OH)}{N=NC(O)Ph}(PPh3)] (3) and [ReCl(O,N‐L){N=NC(O)Ph}(PPh3)2] [O,N‐L = N(=O)CH2COO (4), HN=C(Me)COO (5), C5H4N(COO) (6)], withchelating N,O‐ligands (amino alkoxides, amino‐, oxyamino‐,imino‐ and pyridinocarboxylates) have been prepared by treatment of [ReCl2{N=NC(O)Ph}(PPh3)2] (1) with triethanolamine [N(CH2CH2OH)3],N,N‐bis(2‐hydroxyethyl)glycine [N(CH2CH2OH)2(CH2COOH)],N‐hydroxyiminodiacetic acid [HON(CH2COOH)2],N‐hydroxy‐2,2'‐iminodipropionic acid [HON{CH(Me)COOH}2] and picolinic acid (NC5H4COOH‐2), respectively. The N,O‐ligands in4and5result from fragmentation of theN‐hydroxyiminodicarboxylic acids. All the complexes have been characterized by IR,1H and13C NMR spectroscopy, FAB+‐MS, elemental analysis and X‐ray diffraction structural analysis, which indicate a π‐delocalized chelated benzoylhydrazidorhenium ring in1and2, and, in the other complexes, an essentially linear η1‐diazenido ligand that is alwaystransto the O‐coordinated carboxylate moiety of the N,O‐ligand. The complexes act as catalysts (TON values up to about 45) for peroxidative oxidation, by radical mechanisms, of cyclohexane and cyclopentane to the corresponding alcohols and ketones, under mild conditions (room temperature, use of aqueous H2O2and without added acid). This is an unprecedented use of inorganic Re coordination compounds as catalysts in alkane functionalization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Trigonal‐Prismatic vs. Octahedral Geometry for MnII Complexes with Innocent Didentate Ligands: A Subtle Difference as Shown by XRD and DFT on [Mn(acac)2(bpy)]
Authors: van Gorkum Remy , Buda Francesco , Kooijman Huub , Spek Anthony L. , Bouwman Elisabeth , Reedijk Jan
Published: June 2005

In this paper the first example of a mixed‐ligand MnII complex, having a trigonal‐prismatic coordination geometry with simple, innocent, didentate ligands is presented. The solution and solid‐state structures of [Mn(acac)2(bpy)] as studied by EPR spectroscopy, magnetic susceptibility measurements and XRD are presented: single crystals are hexagonal, space group P61 with unit cell dimensions a = 8.0482(9) Å, c = 51.602(10) Å, V = 2894.6(7) Å3 and Z = 6. The complex has the trigonal‐prismatic geometry only in the solid state. Density functional theory (DFT) calculations were performed to address the question of the preference for a specific coordination geometry in the related MnII complexes [Mn(acac)2(bpy)] (trigonal prismatic) and [Mn(acac)2(phen)] (distorted octahedral). Based on the very small energy differences for the calculated trigonal‐prismatic and octahedral structures it has been concluded that crystal packing effects must contribute largely in determining the trigonal‐prismatic structure for [Mn(acac)2(bpy)]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation and Characterization of CoII, NiII, and ZnII Complexes of Sterically Demanding Hexaazamacrocyclic Dithiophenolates
Authors: Gressenbuch Mathias , Lozan Vasile , Steinfeld Gunther , Kersting Berthold
Published: June 2005

N‐Alkylated variants of a Robson‐type 24‐membered hexaazamacrocyclic dinucleating dithiophenolate ligand bearing ethyl and propyl groups have been prepared and their ligating properties towards the 3d elements Ni, Co and Zn have been examined. The new ligands support the formation of dinuclear complexes of the type [(LR)MII2(L')]+, i.e. [(LEt)Ni2(Cl)]+ (7), [(LPr)Ni2(Cl)]+ (8), [(LEt)Ni2(OAc)]+ (9), [(LPr)Ni2(OAc)]+ (10), [(LEt)Ni2(O2COMe)]+ (11), [(LEt)Ni2(O2COEt)]+ (12), [(LEt)Zn2(OAc)]+ (14), [(LEt)Co2(Cl)]+ (17), and [(LEt)Co2(OAc)]+ (18), the overall structures of which are very similar to the corresponding complexes of the parent permethylated ligand system. The use of the longer alkyl chains expands the binding pocket of the complexes to a more conical, “calixarene”‐like cavity and has allowed for the isolation of the trication [(HLEt)Ni2]3+ (13), which is an intermediate in the substitution reactions of 7. Complex 13 reveals a new coordination mode of the supporting ligand with adjacent four‐ and five‐coordinate nickel atoms. Its higher stability is presumably a consequence of the increased steric crowding imposed by the longer alkyl chains of (LEt)2–. These results have thus demonstrated that these highly functionalized ligand systems allow for the stabilization of reactive intermediates. This information can now be used as a guide to further modulate the chemical reactivity of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Complex Formation of ICL670 and Related Ligands with FeIII and FeII
Authors: Steinhauser Stefan , Heinz Uwe , Bartholomä Mark , Weyhermüller Thomas , Nick Hanspeter , Hegetschweiler Kaspar
Published: June 2005

The pFe values of the two ligands H3Lx and H3Ly in section 2.3 on page 4183 of the original article[1] are incorrect; the corresponding sentence with the correct values should read as follows: In general, the iron binding properties of H3Lx and H3Ly are indeed closely related: the pFe values[30] for H3Lx and H3Ly (total [L] = 10 μM, total [Fe] = 1 μM, pH = 7.4, H2O, I = 0.1 M) are 23.5 and 22.6, respectively.
Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl)ruthenium(II) Immobilized in Humic Acid‐Silica‐Poly(vinyl alcohol) Composite Films
Authors: Ding Shou‐Nian , Xu Jing‐Juan , Chen Hong‐Yuan
Published: June 2005

In this paper, we report the first attempt to use humic acid (HA) as modifiers to prepare the organic‐inorganic hybrid modified glassy carbon electrodes based on HA‐silica‐PVA (poly(vinyl alcohol)) sol‐gel composite. Electroactive species of tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy)$\rm{ {_{3}^{2+}}}$) can easily incorporate into the HA‐silica‐PVA films to form Ru(bpy)$\rm{ {_{3}^{2+}}}$ modified electrodes. The amount of Ru(bpy)$\rm{ {_{3}^{2+}}}$ incorporated in the composite films strongly depends on the amount of HA in the hybrid sol. Electrochemical and electrogenerated chemiluminescence (ECL) of Ru(bpy)$\rm{ {_{3}^{2+}}}$ immobilized in HA‐silica composite films coated on a glassy carbon electrode have been studied with tripropylamine (TPA) as the coreactant. The analytical performance of this modified electrode was evaluated in a flow injection analysis (FIA) system with a homemade flow cell. The as‐prepared electrode showed good stability and high sensitivity. The detection limits (S/N=3) were 0.050 μmol L−1 for TPA and 0.20 μmol L−1 for oxalate, and the linear ranges were from 0.10 μmol L−1 to 1.0 mmol L−1 for TPA and from 1.0 μmol L−1 to 1.0 mmol L−1 for oxalate, respectively. The resulting electrodes were stable over two months.
Novel Ytterbium(III) Selective Membrane Sensor Based on N‐(2‐Pyridyl)‐N′‐(2‐Methoxyphenyl)‐Thiourea as an Excellent Carrier and Its Application to Determination of Fluoride in Mouth Wash Preparation Samples
Authors: Ganjali Mohammad Reza , Rasoolipour Solmaz , Rezapour Morteza , Norouzi Parviz , Tajarodi Azadeh , Hanifehpour Yousef
Published: June 2005

The construction, performance, and applications of a novel ytterbium(III) sensor based on N‐(2‐pyridyl)‐N′‐(2‐methoxyphenyl)‐thiourea (PMT), as an excellent carrier, in plasticized poly(vinyl chloride) PVC matrix, is described. The influences of membrane composition and pH on the potentiometric response of the sensor were investigated. The sensor exhibits a nice Nernstian response for Yb(III) ion over a wide concentration range of 4 decades of concentration (1.0×10−6–1.0×10−2 M), and a detection limit of 5.0×10−7 M. The response time of the electrodes is between 8 and 10 s, depending on the concentration of ytterbium(III) ions. The proposed sensor can be used for about 8 weeks without any considerable divergence in potential. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. The best performance was observed for the membrane containing; 30% PVC, 59% o‐nitrophenyloctyl ether (NPOE) as solvent mediator, 7% PMT, and 4% sodium tetraphenyl borate (NaTPB). It was successfully applied as indicator electrodes in the potentiometric titration of Yb(III) with EDTA and for the determination of fluoride ion in two mouth wash formulations. The proposed La(III) sensor was found to work well under laboratory conditions. It was also used as an indicator electrode in titration of a 1.0×10−4 M of Yb(III) with a standard EDTA solution (1.0×10−2 M). It was also used for determination of Yb(III) ion in Xenotime .
Diagnostic Implications of Uric Acid in Electroanalytical Measurements
Authors: Dutt Jodi S. N. , Cardosi Marco F. , Livingstone Callum , Davis James
Published: June 2005

Urate has a long history in clinical analysis and has served as an important diagnostic in a number of contexts. The increasing interest in metabolic syndrome has led to urate being used in combination with a number of other biomarkers in the assessment of cardiovascular risk. The traditional view of urate as principally an interferent in electrochemical measurement is now gradually being replaced with the realization that its measurement could serve as an invaluable secondary (if not primary) marker when monitoring conditions such as diabetes and heart disease. Rather than attempting to wholly exclude urate electrochemistry, many strategies are being developed that can integrate the urate signal within the device architecture such that a range of biomarkers can be sequentially assessed. The present review has sought to rationalize the clinical importance that urate measurements could hold in future diagnostic applications – particularly within near patient testing contexts. The technologies harnessed for its detection and also those previously employed for its removal are reviewed with the aim of highlighting how the seemingly contrasting approaches are evolving to aid the development of new sensing devices for clinical analysis.
Stripping Analysis at Bismuth Electrodes: A Review
Authors: Wang Joseph
Published: June 2005

For many years mercury electrodes were the transducer of choice in stripping voltammetry of trace metals owing to their high sensitivity, reproducibility, and renewability. However, because of the toxicity of mercury, alternative (‘environmentally friendly’) electrode materials are highly desired for both centralized and field applications. Recently introduced bismuth electrodes offer a very attractive alternative to commonly used mercury electrodes. Such electrodes display well‐defined, undistorted and highly reproducible response, favorable resolution of neighboring peaks, high hydrogen evolution, with good signal‐to‐background characteristics comparable to those of common mercury electrodes. The attractive stripping behavior of bismuth electrodes reflects the ability of bismuth to form ‘fused’ multicomponent alloys with heavy metals. Bismuth stripping electrodes thus hold great promise for decentralized metal testing, with applications ranging from continuous remote sensing to single‐use measurements. Fundamental studies aimed at understanding the behavior of bismuth film electrodes should lead to rational preparation and operation of reliable alternative (‘non–mercury’) stripping electrodes that would have a major impact upon electroanalysis of trace metals. This article reviews the development, behavior, scope and prospects of bismuth electrodes for stripping‐based electrochemical measurements of trace metals.
Characterization and Application of Bismuth‐Film Modified Carbon Film Electrodes
Authors: Pauliukaitė Rasa , Brett Christopher M. A.
Published: June 2005

Bismuth film electrodes, formed by electrochemical deposition on carbon film resistor electrode substrates at constant applied potential, by potential cycling or at constant applied current have been investigated for the first time. The electrochemical behaviour of the films was characterised by cyclic voltammetry and electrochemical impedance spectroscopy and they were applied to the determination of Zn, Cd, and Pb by square‐wave anodic stripping voltammetry. The highest sensitivities coupled with nanomolar detection limits were achieved at bismuth films formed at constant potential; however, in situ deposited bismuth films exhibited better reproducibility. Future application as small, short‐term‐use sensors is indicated.
Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes
Authors: Bragato Carlo , Daniele Salvatore , Baldo M. Antonietta
Published: June 2005

The reduction process of monoprotic weak acids (lactic and acetic acid, and dihydrogen phosphate ion) and mixtures of a strong and a weak acid (perchloric and one of the above weak acids) have been investigated by square‐wave voltammetry (SWV) at a platinum microelectrode 12.5 μm radius. The SW measurements have been performed at low frequencies (i.e., 3 Hz), where the heterogeneous electron transfer process, involving hydrogen evolution (2H++2e=H2), is essentially reversible, and non‐planar diffusion conditions prevail in the mass transport. Under these conditions, the forward and the reverse current‐potential profiles are sigmoidal, whereas the net current‐potential profile is peak shaped. The influence of dissociation constant and analytical concentration of the weak acid on the features of the square‐wave voltammograms has been examined in detail. In general, both these characteristics of the weak acids affect the square‐wave parameters peak potential (Ep), width at half height (W1/2) and net peak current (ip) in a complex manner. Their dependence on concentration is due to the 2 : 1 stoichiometry of the heterogeneous electron transfer, while the dissociation constant contribution arises because of the CE mechanism involved in the overall electrode process. The kinetic of the homogeneous reaction has been investigated by the use of the forward current plateau (achieved by the end of the sweep) along with a theoretical equation. Mixtures of a strong and a weak acid can provide one or two waves, depending on the acid strength and on the analytical concentration of each acid. Peak potential differences of about 80 mV are needed to discern two peaks. Calibration plots, examined for all the weak acids, have shown that linearity may exist only over relatively small concentration ranges.
Gallium(III)‐Schiff Base Complexes as Novel Ionophores for Fluoride Selective Polymeric Membrane Electrodes
Authors: Mitchell‐Koch Jeremy T. , Malinowska Elzbieta , Meyerhoff Mark E.
Published: June 2005

Gallium(III)‐Schiff base complexes are examined as potential ionophores for the development of fluoride ion‐selective polymeric membrane electrodes. To probe the effect of ionophore structure, several different salen and salophen compounds have been synthesized and tested in plasticized poly(vinyl chloride) membranes (H21–5). A salophen ligand structure highly substituted with t‐butyl groups (H21) was found to be optimal with respect to membrane compatibility, and its corresponding Ga(III) complex yields membrane electrodes with greatly enhanced potentiometric selectivity for fluoride ion over a host of other anions. Addition of lipophilic anionic sites into the membrane phase provides optimized response and selectivity, indicating that the Ga1 ionophore functions as a charge carrier. The use of dioctylsebacate as the membrane plasticizer helps reduce any dimer‐monomer equilibria in the membrane phase, yielding sensors with rapid and fully reversible EMF response. Optimal potentiometric detection of fluoride is achieved in solutions buffered to relatively low pH values (pH 3.0), to reduce anionic response to hydroxide. The use of gallium(III)‐Schiff base complexes is shown to offer a promising research direction to ultimately achieve polymeric membrane fluoride sensors that exhibit potentiometric response equivalent to the classical lanthanum fluoride‐based solid state type membrane electrode.
Thermoresponsive Poly‐N‐isopropylacrylamide Gels Modified with Colloidal Gold Nanoparticles for Electroanalytical Applications. 1. Preparation and Characterization
Authors: Kazimierska Ewa A. , Ciszkowska Malgorzata
Published: June 2005

Preparation and spectroscopic and electrochemical characterization of thermoresponsive poly‐N‐isopropylacrylamide (NIPA) hydrogels modified with gold colloidal nanoparticles is described. Gold nanoparticles of various sizes in the range from 2.7 to 18 nanometers in diameter were synthesized and introduced to NIPA polymeric gels during the polymerization process. Dry, ground polymers were reswelled by solutions of well‐known and well‐controlled composition. Such polymeric gels undergo discontinuous reversible volume phase transition in response to temperature increase; this results in a release of up to 90% of solvent from the polymeric matrix. The potential window was determined in NIPA gels modified with gold nanoparticles and compared to that in pure NIPA gels. Diffusion coefficients of electroactive probes in NIPA gels modified with gold and in expelled solutions were determined. It was found that diffusion coefficients of Fc(MeOH)2 in swollen neat NIPA and NIPA‐gel modified with gold nanoparticles are identical within experimental error and they are approximately 10–30% smaller than those in aqueous solutions. Concentration of Fc(MeOH)2 in expelled solutions was up to 30% smaller than in swollen gel. Mole fractions of electroactive probes in collapsed gels and expelled solutions were also determined.
Modulation of the genotoxicity of pesticides reacted with redox‐modified smectite clay
Authors: Sorensen Kara C. , Stucki Joseph W. , Warner Richard E. , Wagner Elizabeth D. , Plewa Michael J.
Published: May 2005

Pesticides are toxic agents intentionally released into the environment; their use raises public health and environmental concerns. In recent years there has been much attention to the biotic degradation of pesticides. Abiotic mechanisms in the soil can contribute to pesticide degradation yet the toxicological impact of such degradation is unclear. This study combines for the first time an investigation into abiotic mechanisms of degradation coupled with toxicological endpoints in mammalian cells. The genotoxicity of three commonly used agricultural pesticides was assessed before and after exposure to redox‐modified clay minerals. The objectives of the study were to determine the genotoxicity of 2,4‐dichlorophenoxy acetic acid (2,4‐D), dicamba, and oxamyl, using single cell gel electrophoresis with Chinese hamster ovary (CHO) cells, and to determine the effect of the iron oxidation state in clay minerals (ferruginous smectite SWa‐1) on the genotoxic potency of the pesticides. 2,4‐D alone or following reaction with redox‐modified clays did not induce DNA damage in CHO cells. Oxamyl alone induced a concentration‐dependent increase in genomic DNA damage; however, its genotoxicity declined after reaction with reduced clay minerals. Dicamba was not genotoxic when directly analyzed. When dicamba was reacted with reduced clay, a concentration‐dependent increase in genomic DNA damage was observed. This is the first reported case of a pesticide being converted into a genotoxin after exposure to redox‐modified smectites. These data introduce a new paradigm on the interaction between redox‐modified clays and pesticide‐related environmental genotoxicity. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Altered centrosomes in ataxia‐telangiectasia cells and rapamycin‐treated Chinese hamster cells
Authors: Bonatti Stefania , Simili Marcella , Benedetti Pier Alberto , Morandi Fabio , Menichini Paola , Carratore Renata Del , Barale Roberto , Abbondandolo Angelo
Published: May 2005

Rapamycin induces chromosome malsegregation in mammalian cell lines and yeast. Previous studies indicate that the function impaired in ataxia‐telangiectasia (A‐T) patients is necessary for both the growth inhibition and the chromosome malsegregation induced by rapamycin, and that treating the non‐tumorigenic Chinese hamster cell line CHEF/18 with rapamycin results in supernumerary centrosomes and multipolar spindles. In this paper we report that lymphoblastoid cell lines established from A‐T patients as well as hamster A‐T‐like cells are more resistant to rapamycin than the respective normal cell lines. Two cell lines derived from Nijmegen Breakage Syndrome (NBS) patients, who have clinical symptoms similar to those of A‐T but a different molecular defect, were not resistant to rapamycin. Both A‐T lymphoblastoid cells and A‐T‐like fibroblasts had giant centrosomes formed by more than two areas of γ‐tubulin‐reacting material. Such giant centrosomes were also observed in CHEF/18 cells after prolonged treatment with rapamycin. Formation of giant centrosomes, possibly due to the coalescence of supernumerary centrosomes, was associated with increased aneuploidy in treated cells. Expression analysis of cell‐cycle regulatory genes in rapamycin‐treated human lymphoblastoid cells indicated that rapamycin decreased the expression of the tumor suppressor geneGADD45. The levels ofRB,p21andp53mRNA were also decreased, although to a lesser extent. As rapamycin is often used as an immunosuppressant in pediatric transplant patients, these data indicate that caution should be taken, especially when the drug is given for prolonged periods of time. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Involvement of oxygen free radicals in the serum‐mediated increase of benzoquinone genotoxicity
Authors: Fabiani Roberto , De Bartolomeo Angelo , Morozzi Guido
Published: May 2005

The genotoxicity of benzoquinone (BQ), a toxic benzene metabolite, is greatly enhanced by the presence of fetal calf serum (FCS) in the incubation medium. The FCS effect is abolished by heat denaturation of serum proteins and is slightly decreased by dialysis. In the present study, we have further investigated the serum effect on BQ genotoxicity by measuring DNA damage produced in peripheral blood mononuclear cells (PBMCs) using the Comet assay. We have also evaluated the effect of human serum and rat liver post‐mitochondrial fraction (S9) on the DNA damage produced by BQ. Both human serum and a rat liver S9 enhanced the genotoxicity of BQ in a manner similar to FCS. Gel filtration experiments showed that all the enhancing activity of the serum eluted with the high molecular weight fractions, suggesting that low molecular weight serum constituents do not play an important role in modulating genotoxicity. The genotoxicity‐enhancing activity of serum was inhibited by the iron chelator deferoxamine and by superoxide dismutase and catalase. Incubating PBMCs with BQ in the presence of FCS also resulted in the accumulation of intracellular peroxides as demonstrated by loading the cells with 2′,7′‐dichlorofluorescin diacetate and analyzing for peroxide formation by flow cytometry. These results indicate that oxygen free radicals are involved in the enhancement of BQ‐induced DNA damage by serum. We hypothesize that enzyme activities that reduce BQ by transferring single electrons could be the source of the oxygen free radicals. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Substructural first‐ and second‐order model identification for structural damage assessment
Authors: Tee K. F. , Koh C. G. , Quek S. T.
Published: May 2005

This paper presents two methods to perform system identification at the substructural level, taking advantage of reduction in the number of unknowns and degrees of freedom (DOFs) involved, for damage assessment of fairly large structures. The first method is based on first‐order state space formulation of the substructure where the eigensystem realization algorithm (ERA) and the observer/Kalman filter identification (OKID) are used. Identification at the global level is then performed to obtain the second‐order model parameters. In the second method, identification is performed at the substructural level in both the first‐ and second‐order model identification. Both methods are illustrated using numerical simulation studies where results indicate their significantly better performance than identification using the global structure, in terms of efficiency and accuracy. A 12‐DOF system and a fairly large structural system with 50 DOFs are used where the effects of noisy data are considered. In addition to numerical simulation studies, laboratory experiments involving an eight‐storey frame model are carried out to illustrate the performance of the proposed method. The identification results presented in terms of the stiffness integrity index show that the proposed methodology is able to locate and quantify damage fairly accurately. Copyright © 2005 John Wiley & Sons, Ltd.
Microglial EP2 is critical to neurotoxicity from activated cerebral innate immunity
Authors: Shie Feng‐Shiun , Montine Kathleen S. , Breyer Richard M. , Montine Thomas J.
Published: May 2005

Prostaglandin (PG) E2 acts via four functionally antagonistic E‐prostanoid (EP) receptors that are expressed on multiple cell types in the nervous system; these are designated EP1–4. We showed previously that EP2 null mice are protected from CD14‐dependent neuronal damage in vivo following intracerebroventricular (ICV) injection of lipopolysaccharide (LPS). Clear interpretation of this neuroprotective outcome is limited because EP2 is expressed on glia and neurons. We tested the hypothesis that microglial EP2 is required for paracrine neurotoxicity following activation of innate immunity, using primary murine microglia and neuron co‐cultures. We demonstrated that microglial EP2 was necessary for lipopolysaccharide (LPS)‐activated microglia‐mediated neurotoxicity, as well as induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX‐2). Genetic deletion of microglial iNOS, pharmacological suppression of COX‐2 activity, or addition of exogenous superoxide dismutase (SOD) and catalase in the presence of EP2 also abolished neurotoxicity. This loss of paracrine neurotoxicity by EP2−/− microglia occurred in the absence of reduced cytokine levels. We conclude that microglial EP2 is critical to innate immunity‐mediated paracrine damage to neurons involving COX‐2 and iNOS. EP2 should be considered as a therapeutic target for suppression of microglial innate immunity‐mediated damage in neurodegenerative diseases. © 2005 Wiley‐Liss, Inc.
Involvement of β1 integrin in microglial chemotaxis and proliferation on fibronectin: Different regulations by ADP through PKA
Authors: Nasu‐Tada Kaoru , Koizumi Schuichi , Inoue Kazuhide
Published: May 2005

Microglia are immune cells in the brain; their activation, migration, and proliferation have pivotal roles in brain injuries and diseases. Microglia are known to attach firmly to fibronectin, the upregulation of which is associated with several pathological conditions in the CNS, through β1 integrin and become activated. Extracellular nucleotides can serve as potent signaling molecules. Recently, ATP and ADP were revealed to possess chemoattractive properties to microglia via Gi‐coupled P2Y receptors. In the present study, we report that the ADP‐induced chemotaxis of microglia is mediated by P2Y12/13 receptors and is β1 integrin‐dependent in the presence of fibronectin. Signals from P2Y12/13 receptors also cause β1 integrin translocation to the membrane ruffle regions, but this redistribution was lost when the intracellular cyclic AMP (cAMP) was increased by forskolin or dibutyryl cAMP. This inhibitory effect of cAMP‐elevating agents did not appear when microglia were co‐incubated with a protein kinase A (PKA) inhibitor, KT‐5720, suggesting that PKA is a negative regulator of the β1 integrin translocation. We also show that the engagement of β1 integrin enhanced microglial proliferation. Signals from P2Y12/13 receptors attenuated the proliferation, whereas ADP itself had no effect on microglial growth. Furthermore, β1 integrin‐induced proliferation is positively regulated by the cAMP‐dependent PKA. Together, these results indicate the involvement of β1 integrin in microglial proliferation and chemotaxis, both of which have clinical importance. The data also suggest that PKA is inversely involved in these two cellular functions. © 2005 Wiley‐Liss, Inc.
Interactive role of the toll‐like receptor 4 and reactive oxygen species in LPS‐induced microglia activation
Authors: Qin Liya , Li Guorong , Qian Xun , Liu Yuxin , Wu Xuefei , Liu Bin , Hong Jau‐Shyong , Block Michelle L.
Published: May 2005

Microglia are activated by lipopolysaccharide (LPS) to produce neurotoxic pro‐inflammatory factors and reactive oxygen species (ROS). While a multitude of LPS receptors and corresponding pathways have been identified, the detailed mechanisms mediating the microglial response to LPS are unclear. Using mice lacking a functional toll‐like receptor 4 (TLR4), we demonstrate that TLR4 and ROS work in concert to mediate microglia activation, where the contribution from each pathway is dependent on the concentration of LPS. Immunocytochemical staining of microglia in neuron–glia cultures with antibodies against F4/80 revealed that while TLR4+/+ microglia were activated the low concentration of 1 ng/ml of LPS, TLR4−/− microglia exhibit activated morphology in response to LPS only at higher concentrations (100–1,000 ng/ml). Additionally, tumor necrosis factor‐α (TNF‐α) was only produced from higher concentrations (100–1,000 ng/ml) of LPS in TLR4−/− enriched microglia cultures. Diphenylene iodonium (DPI), an inhibitor of NADPH oxidase, reduced TNF‐α production from TLR4−/− microglia. The influence of TLR4 on LPS‐induced superoxide production was tested in rat enriched microglia cultures, where the presence or absence of serum failed to show any effect on the superoxide production. Further, both TLR4−/− and TLR4+/+ microglia showed a similar increase in extracellular superoxide production when exposed to LPS (1–1,000 ng/ml). These data indicate that LPS‐induced superoxide production in microglia is independent of TLR4 and that ROS derived from the production of extracellular superoxide in microglia mediates the LPS‐induced TNF‐α response of both the TLR4‐dependent and independent pathway. © 2005 Wiley‐Liss, Inc.