bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacoproteomic analysis of prechemotherapy and postchemotherapy plasma samples from patients receiving neoadjuvant or adjuvant chemotherapy for breast carcinoma
Authors: Pusztai Lajos , Gregory Betsy W. , Baggerly Keith A. , Peng Bo , Koomen John , Kuerer Henry M. , Esteva Francisco J. , Symmans W. Fraser , Wagner Peter , Hortobagyi Gabriel N. , Laronga Christine , Semmes O. John , Wright George L. , Drake Richard R. , Vlahou Antonia
Published: March 2004

BACKGROUND

In this study, proteomic changes were examined in response to paclitaxel chemotherapy or 5‐fluorouracil, doxorubicin, and cyclophosphamide (FAC) chemotherapy in plasma from patients with Stage I–III breast carcinoma. The authors also compared the plasma profiles of patients with cancer with the plasma profiles of healthy women to identify breast carcinoma–associated protein markers.

METHODS

Sixty‐nine patients and 15 healthy volunteers participated in the study. Plasma was sampled on Day 0 before chemotherapy and on Day 3 posttreatment in the 69 patients or 3 days apart in the 15 healthy women. Twenty‐nine patients received preoperative chemotherapy, and 40 received postoperative chemotherapy. Surface‐enhanced laser desorption/ionization mass spectrometry was used to generate protein mass profiles.

RESULTS

Few changes were observed in plasma during treatment. Only 1 protein peak was identified (mass/charge ratio [m/z], 2790) that was induced by paclitaxel and, to a lesser extent, by FAC chemotherapy. This proteomic response was detectable in 80% of patients who were treated preoperatively but also was present with lesser intensity in approximately 40% of patients treated postoperatively. There was no clear correlation between induction of m/z 2790 during a single course of treatment and final tumor response to preoperative chemotherapy. Five other peaks also were identified that discriminated between plasma from patients with breast carcinoma and plasma from normal women. These same peaks also were detectable in a subset of patients who already had undergone surgery to remove their tumors.

CONCLUSIONS

A single chemotherapy‐inducible SELDI‐MS peak and five other peaks that distinguished plasma obtained from patients with breast carcinoma from plasma obtained from normal, healthy women were identified. The (as yet unsequenced) proteins represented by these peaks are candidate markers of micrometastatic disease after surgery. Cancer 2004. © 2004 American Cancer Society.
Distribution of soluble guanylyl cyclase in the rat brain
Authors: Ding Jin‐Dong , Burette Alain , Nedvetsky Pavel I. , Schmidt Harald H.H.W. , Weinberg Richard J.
Published: March 2004

The diffusible messenger nitric oxide (NO) acts in the brain largely through activation of soluble guanylyl cyclase (sGC), a heterodimer comprising α and β subunits. We used immunohistochemistry to study the distribution of both sGC subunits in the brain of adult rats. α and β subunits gave similar widespread staining throughout the CNS, which was strongest in neostriatum, olfactory tubercle, and supraoptic nucleus. Double‐labeling experiments showed striking cellular colocalization in most brain regions, suggesting that the two subunits may be organized into enzymatically active α/β heteromers. Mismatches were observed in cerebellar cortex: Purkinje cells and Bergmann glia were positive for both subunits, whereas granule cells and interneurons in the molecular layer were strongly immunopositive for β but only weakly stained for the α subunit. By using multiple labeling, we compared the localization of sGC with neuronal nitric oxide synthase (NOS‐I, the NO‐producing enzyme in neurons). In forebrain, the distribution of sGC and NOS‐I was complementary, with only occasional colocalization. In contrast, cellular colocalization was common in midbrain and cerebellum. These data support a widespread role for the NO/sGC/cGMP pathway in the CNS and suggest that, in addition to its role as paracrine messenger, NO may also be an intracellular autocrine agent. J. Comp. Neurol. 472:437–448, 2004. © 2004 Wiley‐Liss, Inc.
Tectal mosaic: Organization of the descending tectal projections in comparison to the ascending tectofugal pathway in the pigeon
Authors: Hellmann Burkhard , Güntürkün Onur , Manns Martina
Published: March 2004

The optic tectum of vertebrates is an essential relay station for visuomotor behavior and is characterized by a set of connections that comprises topographically ordered input from the eyes and an output that reaches premotor hindbrain regions. In the avian tectofugal system, different ascending cell classes have recently been identified based on their dendritic and axonal projection patterns, although comparable information about the descending cells is missing. By means of retrograde tracing, the present study describes the detailed morphology of tectal output neurons that constitute the descending tectobulbar and tectopontine pathways in pigeons. Descending cells were more numerous in the dorsal tectum and differed in terms of 1) their relative amount of ipsi‐ vs. contralateral projections, 2) the location of the efferent cell bodies within different tectal layers, and 3) their differential access to visual input via dendritic ramifications within the outer retinorecipient laminae. Thus, the descending tectal system is constituted by different cell classes presumably processing diverse aspects of the visual environment in a visual field‐dependent manner. We demonstrate, based on a careful morphological analysis and on double‐labeling experiments, that the descending pathways are largely separated from the ascending projections even when they arise from the same layers. These data support the concept that the tectum is arranged as a mosaic of multiple cell types with diverse input functions at the same location of the tectal map. Such an arrangement would enable the tectal projections onto diverse areas to be both retinotopically organized and functionally specific. J. Comp. Neurol. 472:395–410, 2004. © 2004 Wiley‐Liss, Inc.
In vitro analyses of interactions between olfactory receptor growth cones and glial cells that mediate axon sorting and glomerulus formation
Authors: Tucker Eric S. , Oland Lynne A. , Tolbert Leslie P.
Published: March 2004

During development, the axons of olfactory receptor neurons project to the CNS and converge on glomerular targets. For vertebrate and invertebrate olfactory systems, neuron–glia interactions have been hypothesized to regulate the sorting and targeting of olfactory receptor axons and the development of glomeruli. In the moth Manduca sexta, glial reduction experiments have directly implicated two types of central olfactory glia, the sorting zone‐ and neuropil‐associated glia, in key events in olfactory development, including axon sorting and glomerulus stabilization. By using cocultures containing central olfactory glial cells and explants of olfactory receptor epithelium, we show that olfactory receptor growth cones elaborate extensively and cease advancement following contact with sorting zone‐ and neuropil‐associated glial cells. These effects on growth cone behavior were specific to central olfactory glia; peripheral glial cells of the olfactory nerve failed to elicit similar responses in olfactory receptor growth cones. We propose that sorting zone‐ and neuropil‐associated glial cells similarly modify axon behavior in vitro by altering the adhesive properties and cytoskeleton of olfactory receptor growth cones and that these in vitro changes may underlie functionally relevant changes in growth cone behavior in vivo. J. Comp. Neurol. 472:478–495, 2004. © 2004 Wiley‐Liss, Inc.
The 5‐HT2A receptor is widely distributed in the rat spinal cord and mainly localized at the plasma membrane of postsynaptic neurons
Authors: Doly Stéphane , Madeira Alexandra , Fischer Jacqueline , Brisorgueil Marie‐Jeanne , Daval Genevieve , Bernard Rozenn , Vergé Daniel , Conrath Marie
Published: March 2004

Serotonin (5‐HT) plays a major role at the spinal level by modulating most spinal functions through several receptor subtypes including the 5‐HT2A receptor. To gain further insight into the cellular role of this receptor, we performed an immunocytochemical study of 5‐HT2A receptors in the rat spinal cord, at light and electron microscope levels. The results showed that 5‐HT2A receptors were widely distributed in the spinal cord at all segmental levels. Immunolabeling was particularly dense in lamina IX and in the dorsal horn lamina IIi. Immunoreactive cell bodies were numerous in lamina IX, where many but not all motoneurons were labeled, as shown by double labeling with choline acetyltransferase antibodies. Stained cell bodies were also observed in the gray matter. The study at the ultrastructural level focused on the lumbar dorsal horn (laminae I–II) and ventral horn (lamina IX). At both levels, 5‐HT2A immunoreactivity was mainly postsynaptic on dendrites and cell bodies. However, a little presynaptic labeling was also observed in axon and axon terminals, some of them containing large granular vesicles attesting to their peptidergic nature. The main result of our study was the “nonsynaptic” plasma membrane localization of 5‐HT2A receptors covering a large surface of cell bodies and dendrites, suggesting a paracrine form of action of serotonin. These observations are consistent with a double role (pre‐ and postsynaptic) for serotonin on these receptors on various cellular targets. J. Comp. Neurol. 472:496–511, 2004. © 2004 Wiley‐Liss, Inc.
Diversity of contralateral commissural projections in the embryonic rodent spinal cord
Authors: Kadison Stephanie Rebecca , Kaprielian Zaven
Published: March 2004

In vertebrate embryos, the axons of spinal commissural neurons grow toward and across the floor plate, a specialized structure located at the ventral midline. Although the initial segment of this trajectory has been intensively studied, relatively little is known about commissural axon pathfinding on the contralateral side of the floor plate in higher vertebrates. We recently demonstrated that many embryonic mouse and chick spinal commissural axons follow a complex trajectory once they cross the ventral midline. Here we use focal applications of 1,1′‐dioctadecyl‐3,3,3′,3′ tetramethylindocarbocyanine perchlorate (DiI) to identify four different contralateral commissural trajectories, two of which have not previously been described in the embryonic rodent spinal cord. Intermediate longitudinal commissural (ILC) axons travel away from the floor plate along an arcuate trajectory into intermediate regions of the spinal cord. In contrast, medial longitudinal commissural (MLC) axons grow alongside the floor plate, projecting primarily in the rostral direction. Bifurcating longitudinal commissural (BLC) axons branch into rostrally and caudally directed projections. Forked transverse commissural (FTC) axons either execute two orthogonal turns before crossing the floor plate or extend directly across the floor plate. We also show a variation in the relative frequencies of individual contralateral commissural projections along the dorsoventral and anteroposterior axes of the spinal cord. In addition, using a novel culture system, we demonstrate that commissural axons elaborate ILC‐, MLC‐, BLC‐, and FTC‐like trajectories in vitro. These results provide a basis for examining the mechanisms that regulate commissural axon pathfinding on the contralateral side of the floor plate in the embryonic rodent spinal cord. J. Comp. Neurol. 472:411–422, 2004. © 2004 Wiley‐Liss, Inc.
Schwarz alternating method based on natural boundary reduction for time‐dependent problems on unbounded domains
Authors: Du Qikui , Yu Dehao
Published: March 2004

By using the natural boundary reduction an overlapping domain decomposition method is designed to solve some exterior two‐dimensional time‐dependent parabolic problems. The governing equation is first discretized in time, leading to a sequence of boundary value problems with respect to time step in an unbounded domain. Then artificial boundaries are introduced. For each time level, an overlapping domain decomposition method, which is based on the natural boundary reduction, is constructed to solve the exterior elliptic boundary value problem on a two‐dimensional domain. It is shown that the algorithm is equivalent to Schwarz alternating method. The convergence of this algorithm is given. The contraction factor for the exterior circular domain is also discussed. In the end of this paper, some numerical examples are presented, which illustrate the feasibility and the effectiveness of the proposed methods in this paper. Copyright © 2004 John Wiley & Sons, Ltd.
A third‐order accurate time scheme for variably saturated groundwater flow modelling
Authors: Guarracino Luis , Quintana Fernando
Published: March 2004

A numerical algorithm to simulate water flow in variably saturated non‐deformable porous media is presented. The algorithm is based on the numerical approximation of Richards' non‐linear equation. This equation is discretized in time by using a third‐order Crank–Nicholson scheme based on Richardson extrapolation. The proposed time scheme is third‐order accurate and presents advantages over standard time discretizations of Richards' equation. A Galerkin finite element procedure is employed for spatial approximation. Numerical tests showing the performance and numerical properties of the proposed algorithm are presented. Copyright © 2004 John Wiley & Sons, Ltd.
A non‐linear co‐ordinate transformation for accurate numerical evaluation of weakly singular integrals
Authors: Yun Beong In
Published: March 2004

In order to obtain accurate numerical evaluation of weakly singular integrals, we propose a new non‐linear co‐ordinate transformation of the sigmoidal type. The asymptotic behaviour of the present transformation near a singular point is governed by an additional parameter b≠0. Moreover, an analytical form of its inverse is derived, which is available for the case of interior‐point singularity. In the result the presented transformation can improve asymptotic truncation errors of the Gauss–Legendre quadrature rule for weakly singular integrals.

By comparing the present transformation with existing sigmoidal transformations in numerical examples, we show that the former with a proper value of b can result in more accurate evaluation than the others. Copyright © 2004 John Wiley & Sons, Ltd.
Reviewing the application of SEA to sectoral plans in Italy. The case of the mobility plan of an alpine region
Authors: Diamantini Corrado , Geneletti Davide
Published: March 2004

Within the Italian context, the application of SEA is particularly advanced in the Autonomous Province of Trento (APT). The APT recently approved a plan on sustainable development in which the selected sustainability indicators were explicitly considered as the reference for future SEAs. Subsequently, guidelines to carry out the environmental report, i.e. the core document of SEA, were issued and experimentally applied to several sectoral plans. This paper critically reviews the experience of the APT, by focusing on the positive elements and shortcomings that affect the guidelines and their application. The environmental report of the APT's Mobility Plan was selected as a case study. This plan has a high strategic relevance because it deals with several critical issues, such as trans‐alpine traffic. The paper concludes that the approach was set out in an interesting and innovative way, but its application is affected by some limitations, such as the lack of indicator‐based analyses. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Requirements of the SEA Directive and the German Federal Transport Infrastructure Plan
Authors: Wende Wolfgang , Hanusch Marie , Gassner Erich , Guennewig Dieter , Koeppel Johann , Lambrecht Heiner , Langenheld Alexandra , Peters Wolfgang , Roethke‐Habeck Petra
Published: March 2004

This paper presents some preliminary results of a research project started in May 2002 on the German transportation planning system, commissioned by the Federal Environmental Agency. The main aim of this project is to find ways to integrate formal strategic environmental assessment (SEA) and to identify technical and methodological opportunities for implementing the SEA Directive. It reveals that whilst environmental aspects are already taken into account to a reasonable extent, certain amendments are needed in order to fully meet the requirements of the SEA Directive. Furthermore, the paper calls for a new type of ‘Federal Transport Development Plan’. This should focus on an assessment of strategic alternatives as the basis for the integration of individual projects. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Integrating Strategic Environmental Assessment into community development plans — a case study from Austria
Authors: Stoeglehner Gernot
Published: March 2004

‘Community development plans’ contain the objectives and measures for the spatial development of a municipality. Most likely these plans will be within the scope of the SEA Directive. To determine how they perform in terms of the SEA Directive, an ex post survey of an already completed planning process is used. For this purpose two tools are developed by the author: an ‘idealized planning scheme including SEA’ and a ‘natural goods–planning content matrix’. These tools are used to compare the procedures and contents of the planning process of the case study with the SEA demands and to determine the requested amendments for the planning processes. The result of this examination is that the practice of community development planning already largely complies with the SEA Directive. In some phases of the planning process more precise regulations will be needed that have a high potential to contribute to an elevated quality of spatial planning concerning environmental aspects. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Bis‐ and Tris‐DNA Intercalating Porphyrins Designed to Target the Major Groove: Synthesis of Acridylbis‐arginyl‐porphyrins, Molecular Modelling of Their DNA Complexes, and Experimental Tests
Authors: Far Samia , Kossanyi Alain , Verchère‐Béaur Catherine , Gresh Nohad , Taillandier Eliane , Perrée‐Fauvet Martine
Published: March 2004

In order to increase the DNA binding affinity of a bis‐arginyl‐porphyrin which has been previously shown to bind preferentially in the major groove of the d(GGCGCC)2 sequence (Mohammadi et al., Biochemistry 1998, 37, 9165), we have synthesized bis‐ and tris‐intercalating derivatives in which one or both arginyl arms are connected through a flexible chain to an acridine ring. We report here the synthesis of these two molecules along with the molecular modelling of their complexes with a GC‐rich oligonucleotide encompassing the central d(GGCGCC)2 hexamer. The modelling computations showed that when the porphyrin was intercalated into the central d(CpG)2 site with both arginyl side‐chains bonded to the guanines flanking the intercalation site, the acridine ring(s) could intercalate immediately upstream from the central hexamer, but at the cost of substantial DNA conformational energy. A significant preference for major‐groove binding over minor‐groove binding was found. The results of circular dichroism studies and topoisomerase I‐unwinding experiments supported the bis‐ and tris‐intercalation of these derivatives. The bis‐acridyl derivative provided, as expected, greater stabilization against thermal denaturation than the mono‐acridyl and the parent bis‐arginyl‐porphyrin compounds. Based on the modelling results, the structures of derivatives can be tailored to facilitate tris‐intercalation in rigid GC‐rich sequences, and thereby enhance the selective targeting of GC base pairs by the arginyl side‐chains, by lengthening the porphyrin‐acridine connectors. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Chromophoric Azo Reagents for Amino Acid and Peptide Labelling
Authors: Fraga Susana M. B. , Gonçalves Maria S. T. , Moura João C. V. P. , Rani Kavitha
Published: March 2004

Four carboxylic azo dyes, with spectroscopic absorption peaks ranging from 400 to 500 nm, are presented as new markers for amino acid and peptide labelling at their N‐terminus. Labelling can also be performed at side‐chain residues as is exemplified with lysine and serine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Tetrastilbenylmethanes by Wittig−Horner Reactions
Authors: Kim Soungkyoo , Seus Peter , Meier Herbert
Published: March 2004

The all‐(E)‐configured tetrastilbenylmethanes 3a−e and 5a,b can be obtained by fourfold Wittig−Horner reactions. The tetrahedral arrangement of these compounds guarantees independent stilbenoid chromophores with a high chromophore density. Apart from (E)/(Z) isomerization reactions, irradiation leads to a three‐dimensional network with isolated unchanged stilbene units. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Formal Desymmetrization of the Diastereotopic Chains in Gemini Calcitriol Derivatives with Two Different Side Chains at C‐20
Authors: Maehr Hubert , Uskokovic Milan R.
Published: March 2004

Derivatives of calcitriol with two equal side chains emanating at C‐20, also known as gemini, have emerged as interesting compounds, either as instruments for assessing the steric requirements of the vitamin D receptor or as drug candidates. We now describe the syntheses of gemini analogs where the two side chains differ from each other. While retaining the 2‐hydroxy‐2‐methylpentyl moiety, common to both calcitriol and gemini, as one chain, we replaced the other with a 1,1,1‐trifluoro‐2‐hydroxy‐2‐(trifluoromethyl)‐3‐pentynyl group. The features comprising this chain modification are commonly regarded to improve toxicity profiles and drug performance. The resulting epimeric pairs with a new stereogenic center at C‐20 were resolved and the absolute configurations assigned. The side‐chain desymmetrization protocols described herein serve as a basis for additional synthesis activity in this area. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Calystegine B2, B3, and B4 Analogues: Mapping the Structure‐Glycosidase Inhibitory Activity Relationships in the 1‐Deoxy‐6‐oxacalystegine Series
Authors: García‐Moreno M. Isabel , Ortiz Mellet Carmen , García Fernández José M.
Published: March 2004

A practical synthesis of ring‐modified calystegine analogues with a 6‐oxa‐nor‐tropane structure has been developed. The methodology relies on the ability of the masked carbonyl group of hexose precursors to act as the electrophilic target for the nitrogen atom of pseudoamide (urea or thiourea) groups located at the C‐5 position through the open‐chain aldehyde form. The resulting piperidine species undergoes spontaneous intramolecular glycosylation reaction involving 6‐OH provided that the resulting bicyclic aminoacetal fulfils the anomeric effect. The hydroxylation profile of the imino sugar glycomimetics thus obtained can be modified by judicious choice of the monosaccharide template. The validity of the strategy has been demonstrated by the preparation of N‐thiocarbamoyl and N‐carbamoyl derivatives of 1‐deoxy‐6‐oxa‐(+)‐calystegine B2, (−)‐B4, (+)‐B3, and (−)‐B2 from L‐ido, L‐gulo, L‐altro, and D‐ido precursors. The requested thioureas and ureas were obtained from 5‐amino‐ or 5‐azido‐5‐deoxyhexofuranose derivatives by a coupling reaction with isothiocyanates or a tandem Staudinger−aza‐Wittig‐type reaction with triphenylphosphane and an isothiocyanate followed by addition of water to the resulting carbodiimide, respectively. Attempts to prepare analogues with the unnatural 3‐epi‐(+)‐calystegine B2 hydroxylation profile from L‐talofuranose (thio)ureas by this methodology led, however, to equilibrium mixtures of the furanose anomers, with only traces of the nor‐tropane form. Evaluation of the inhibitory activity of the whole series of calystegine analogues against several glycosidases indicated that the main structural requirements for strong and specific inhibition of bovine liver β‐glucosidase/β‐galactosidase are the all‐equatorial orientation of the triol system at the piperidine ring, the presence of a lipophilic substituent at the nitrogen atom and the location of the intramolecular aminoacetal oxygen atom at the 6‐position of the nor‐tropane core. On the basis of these data, a structural analogy of 6‐oxa‐(+)‐calystegine B2 derivatives with the natural calystegine C1 has been established and a 1‐azasugar inhibition mode is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Reactions of 1,3‐Diaryl‐2‐chloropropane‐1,3‐diones with Nucleophiles − Cyanide‐Induced Retro‐Claisen−Claisen Condensation
Authors: Roshchupkina Galina I. , Gatilov Yury V. , Rybalova Tatyana V. , Reznikov Vladimir A.
Published: March 2004

Treatment of some 1,3‐diaryl‐2‐chloropropane‐1,3‐diones, acyclic chloro‐substituted enaminones and β‐oxo esters with nucleophiles was shown to proceed easily with the formation, at least in the first stage, of formal nucleophilic substitution products. Treatment of enaminones and β‐oxo esters with azide and cyanide ions proceeds with the preservation of the skeleton, whereas chloro‐substituted diaroylmethanes undergo retro‐Claisen−Claisen condensation reactions in the course of the reaction with cyanide. Dibenzoylchloromethane reacts with azide and cyanide ions with fragmentation of the molecule and subsequent reassembly, resulting in benzoylated benzaldehyde cyanohydrin and a 1,3‐oxathiol derivative, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Novel Cyclic 1,2‐Diacetals Derived from (2R,3R)‐(+)‐Tartaric Acid: Synthesis and Application as N,O Ligands for the Enantioselective Alkylation of Benzaldehyde by Diethylzinc
Authors: Barros M. Teresa , Maycock Christopher D. , Phillips Ana Maria Faísca
Published: March 2004

A chiral cyclic 1,2‐diacetal derived from tartaric acid was used as the basic structural unit for novel ligands. Monooxazoline carbinols in which the degree of substitution of the alcohol and the nature of the stereocentre in the oxazoline ring were varied were synthesized in moderate to good yields. The influence of these structural factors on asymmetric induction was examined in the enantioselective addition of diethylzinc to benzaldehyde. Up to 60% ee was observed with a secondary or a tertiary alcohol as the metal‐chelating group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electrochromic Application of an Enediyne Scaffolding as a Redox‐Active Chromophore − Synthesis and Redox Behavior of 9,10‐Bis[3‐(6‐azulenyl)‐1‐(6‐azulenylethynyl)‐2‐propynylidene]‐9,10‐dihydroanthracenes
Authors: Ito Shunji , Inabe Haruki , Morita Noboru , Tajiri Akio
Published: March 2004

A bis(enediyne) system utilizing anthraquinodimethane as a platform for a redox‐active substructure that bears azulenes as π‐electron‐accepting groups at the periphery has been prepared by a simple one‐pot reaction involving repeated Pd‐catalyzed alkynylation of 6‐bromoazulenes with the bis(enediyne). The novel bis(enediyne)s exhibited two, one‐step two‐electron redox properties under electrochemical reduction conditions together with a significant color change owing to the generation of a closed‐shell cyanine‐type substructure by the two‐electron reduction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Asymmetric Synthesis of 2‐Amino‐1,3‐diols and D‐erythro‐Sphinganine
Authors: Enders Dieter , Müller‐Hüwen Anke
Published: March 2004

The asymmetric synthesis of protected 2‐amino‐1,3‐diols (S,R)‐5 starting from 2,2‐dimethyl‐1,3‐dioxan‐5‐one is described. The stereogenic centres are generated by α‐alkylation using the SAMP/RAMP hydrazone methodology and diastereoselective reduction of the ketones (S)‐2 with L‐selectride. The resulting alcohols (S,S)‐3 are converted into the amines (S,R)‐4 by nucleophilic substitution with sodium azide and subsequent reduction with lithium aluminium hydride. The products are obtained in high diastereomeric and enantiomeric excesses (de ⩾ 96%, ee = 90−94%). By employing this methodology, the ammonium salt of D‐erythro‐sphinganine (R,S)‐11 was synthesised starting from RAMP‐hydrazone (R)‐1 in 47% overall yield and with excellent diastereomeric and enantiomeric excess (de, ee ⩾ 96%). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Enantioselective Lutidine‐Tetrahydrobenzoxanthene Receptors for Carboxylic Acids
Authors: Oliva Ana I. , Simón Luis , Muñiz Francisco M. , Sanz Francisca , Morán Joaquín R.
Published: March 2004

Receptors based on cis‐ and trans‐tetrahydrobenzoxanthene skeletons combined with benzoxazoles and pyridines have shown enantioselective binding to sulfonylamino acids. The keto‐enol tautomeric equilibrium of the receptors shifts towards the keto form upon complexation. X‐ray analysis of the trans receptor complex with L‐leucine triflamide (H) reveals an unexpected structure, in which the basic pyridine nitrogen accepts the strong H‐bond of the guest, while the benzoxazole acts as a counterpart for the sulfonamide group. l‐Carbamoyllactic acid (C) is a suitable guest for the resolution of the racemic mixture of the trans receptor, which can be performed by impregnating TLC plates with the guest. Extraction of racemic carbamoyllactic acid (C) and its ammonium salt from a chloroform/water system with the trans receptor 4 provided a procedure for the resolution of the guest. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Radical Reactions Using Decacarbonyldimanganese under Biphasic Conditions
Authors: Huther Nathalie , McGrail P. Terry , Parsons Andrew F.
Published: March 2004

Radical reactions of alkyl halides, initiated by photolysis in the presence of decacarbonyldimanganese, can be performed in biphasic media. Reactions in the presence of aqueous sodium hydroxide together with a phase‐transfer catalyst result in the efficient removal of manganese halide by‐products and also lead to the regeneration of decacarbonyldimanganese. A range of efficient radical couplings, cyclisations and intermolecular addition reactions were performed under these conditions. This included the development of a new tandem radical addition−ionic cyclisation sequence that was employed in a short approach to (±)‐coronamic acid. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Spectroelectrochemical Study on the Electrooxidation in Aqueous Medium of some 1,4‐Dihydropyridines: Effects of Substitution in 1‐Position and 4‐Position
Authors: López‐Alarcón C. , Squella J. A. , Miranda‐Wilson D. , Núñez‐Vergara Luis J.
Published: March 2004

Spectroelectrochemical and HPLC characterization of the electrochemical oxidation in aqueous medium of a series of six N‐1 and C‐4 substituted 1,4‐dihydropyridines is presented. Based on the analysis of spectra obtained by in situ spectroscopic measurements it was possible to detect the generation of final oxidation products, which resulted in differences depending of the nature of the substitution on the nitrogen in the dihydropyridine ring. Controlled potential electrolysis (CPE) in aqueous medium was followed by the HPLC technique using EC and PDA detectors. This latter resulted adequately to follow the parent 1,4‐DHP derivatives and their respective oxidation products. Electrochemical oxidation of parent N‐H substituted 1,4‐dihydropyridines generated the corresponding neutral pyridine derivative as final oxidation product. However, the N‐ethyl substituted 1,4‐dihydropyridine derivatives gave rise to the pyridinium salt derivatives.
Square‐Wave Voltammetry of Cathodic Stripping Reactions. Diagnostic Criteria, Redox Kinetic Measurements, and Analytical Applications
Authors: Gulaboski Rubin , Mirčeski Valentin , Komorsky‐Lovrić Šebojka , Lovrić Milivoj
Published: March 2004

A comparative study of different types of cathodic stripping reactions under conditions of square‐wave voltammetry is presented. Cathodic stripping processes involving reactions of second order as well as reactions coupled by adsorption of the reacting ligand are analyzed The inherent parameters, controlling the overall voltammetric behavior of each cathodic stripping electrode reaction are derived. The criteria for qualitative distinguishing of each mechanism are established as well as a methodology for redox kinetic measurements is proposed. The influence of the parameters of the excitation signal on the properties of the voltammetric response is analyzed in order to find optimal conditions for analytical application. The theoretical results are illustrated by the experiments with a series of uracil derivatives.
New Ion‐Pair Based All‐Solid‐State Surfactant Sensitive Sensor for Potentiometric Determination of Cationic Surfactants
Authors: Matešic‐Puac Ruzica , Sak‐Bosnar Milan , Bilic Mate , Grabaric Bozidar S.
Published: March 2004

Cationic surfactants of different types were determined using a few potentiometric sensors based on ion‐pair complexes (dodecyldimethylbenzylammonium dodecylsulfate, dodecylmethylbenzylammonium dodecylbenzensulfonate, tetrahexadecylammonium dodecylsulfate and Hyamine (benzethonium dodecylsulfate)) as sensing materials. The response of the all‐solid state surfactant sensitive electrode based on a Teflonized graphite conducting substrate, coated with a PVC membrane containing sensing material, was investigated in the solutions of Hyamine and hexadecyltrimethylammonium ion in the concentration range from 1 μM to 10 mM. Potentiometric surfactant cation titration has been performed using sodium dodecylsulfate as titrant and an ion‐pair‐based surfactant sensitive electrode as a potentiometric indicator. Several commercial surfactant products have also been titrated and the results were compared with those obtained with two‐phase standard titration method.
Label‐free DNA Hybridization Based on Coupling of a Heated Carbon Paste Electrode with Magnetic Separations
Authors: Wang Joseph , Flechsig Gerd‐Uwe , Erdem Arzum , Korbut Olga , Gründler Peter
Published: March 2004

The technique of electrically heated carbon paste electrodes is applied for label‐free detection of DNA hybridization after magnetic isolation. Coupling of both techniques leads to highly selective and sensitive detection of DNA hybridization. Minimal contributions of nonhybridized DNA are thus coupled to an enhanced signal. Application of elevated temperatures during the accumulation step yields a max. 6‐fold enhancement of guanine oxidation signals compared to room temperature deposition. Use of noncomplementary nucleic acids gives no significant peaks at room or elevated temperatures. The noise level remained unaffected. Variation of the target concentration results in linear calibration plots under hot accumulation conditions.
Determination of Cr(VI) Using a Pulse Amperometric Method with an Ionophore‐Immobilized Membrane Electrode
Authors: Choi Young‐Woo , Moon Seung‐Hyeon
Published: March 2004

A pulse amperometric method for the determination of Cr(VI) in aqueous solution has been investigated with an ionophore‐immobilized membrane electrode. The double potential step chronoamperometry was applied to measure the current for the facilitated transfer of Cr(VI) by the membrane with N,N,N′,N′‐tetrakis(3‐aminopropyl)‐1,4‐butanediamine (DABAm4) coated on a silver electrode. The current responses were stably detected by the pulse amperometry while voltage pulses, ΔE=−240 mV, of short duration of 50 ms were employed at the interval of 5 s. In the range of 1.65–81.3 μM, Cr(VI) in water could be selectively determined in the presence of various interfering anions below 100 μM without removal of Cr(VI) from the interferences using an ion exchange column.
Novel Potentiometric PVC‐Membrane and Coated Graphite Sensors for Lanthanum(III)
Authors: Ganjali Mohammad Reza , Kiani‐Anbouhi Roya , Shamsipur Mojtaba , Poursaberi Tahereh , Salavati‐Niasari Masoud , Talebpour Zahra , Emami Mahdi
Published: March 2004

Preliminary theoretical studies revealed the selective complexation of bis (2‐mercaptoanil) diacetyl (BMDA) with La3+ over several alkali, alkaline earth and heavy metal ions. Thus, novel PVC‐based membrane (PBM) and coated graphite membrane (CGM) sensors for La(III) based on BMDA were prepared. The electrodes display Nernstian behavior over wide concentration ranges (i.e., 1.0×10−5–1.0×10−1 M for PBM and 1.0×10−6–1.0×10−1 M for CGM). The potential response of sensors was pH independent in the range of 4.0–8.0. The sensors possess satisfactory reproducibility, fast response time (<15 s), and specially excellent discriminating ability for La3+ ions with respect to most of the cations. The membrane sensor was used as an indicator electrode in potentiometric titration of lanthanum ions with EDTA. The coated graphite membrane electrode was applied in determination of fluoride ions in mouth wash preparations.
Study of the Electrochemical Behavior of Disperse Blue 1‐Modified Graphite Electrodes. Application to the Flow Determination of NADH
Authors: Stergiou Dimitrios V. , Prodromidis Mamas I. , Veltsistas Panayotis G. , Evmiridis Nikolaos P.
Published: March 2004

The preparation and the electrochemical study of Disperse Blue 1‐chemically modified electrodes (DB1‐CME), as well as their efficiency for the electrocatalytic oxidation of NADH is described. The proposed mediator was immobilized by physical adsorption onto graphite electrodes. The electrochemical behavior of DB1‐CME was studied with cyclic voltammetry. The electrochemical redox reaction of DB1 was found to be reversible, revealing two well‐shaped pair of peaks with formal potentials 152 and −42 mV, respectively, (vs. Ag/AgCl/3M KCl) at pH 6.5. The current Ip has a linear relationship with the scan rate up to 800 mV s−1, which is indicative for a fast electron transfer kinetics. The dissociation constants of the immobilized DB1 redox couple were calculated pK1=4 and pK2=5. The electrochemical rate constants of the immobilized DB1 were calculated k1°=18 s−1 and k2°=23 s−1 (Γ=2.36 nmol cm−2). The modified electrodes were mounted in a flow injection manifold, poised at +150 mV (vs. Ag/AgCl/3M KCl) and a catalytic current due to the oxidation of NADH was measured. The reproducibility was 1.4% RSD (n=11 for 30 μM NADH) The behavior of the sensor towards different reducing compounds was investigated. The sensor exhibited good operational and storage stability.
3‐Indoxyl Phosphate as an Electrochemical Substrate for Horseradish Peroxidase
Authors: Fanjul‐Bolado Pablo , González‐García María Begoña , Costa‐García Agustín
Published: March 2004

In this work 3‐indoxyl phosphate (3‐IP), an alkaline phosphatase substrate, is demonstrated to be a suitable substrate for horseradish peroxidase (HRP). HRP catalyzes the oxidation of 3‐IP in presence of hydrogen peroxide (H2O2) generating the product indigo blue, which is an aromatic heterocycle compound insoluble in aqueous solutions. This product was easily converted into its soluble parent compound indigo carmine (IC) (by addition of fuming sulfuric acid to the reaction media) which has a reversible voltammetric peak at the formal potential of −0.15 V (vs. Ag pseudo‐reference electrode) when a screen‐printed carbon electrode (SPCE) is used. Parameters that influence the enzymatic reaction, such as pH, temperature, substrate concentration and reaction time have been optimized. Moreover, the enzyme apparent kinetic constants (Vmax, KM) for both substrates (3‐IP and H2O2) have been calculated. Indirect measurements of HRP activity in solution were carried out not only by cyclic voltammetry but also using amperometric detection in a flow system. The detection limits were 6.86×10−12 and 5.68×10−12 M, respectively. Thus, 3‐IP is the first substrate that could be used for alkaline phosphatase (AP) and HRP, the most common enzymatic labels in affinity assays.
The Electrochemical Behavior of α‐Ketoglutarate at the Hanging Mercury Drop Electrode in Acidic Aqueous Solution and Its Practical Application in Environmental and Biological Samples
Authors: Yang Li , Yang Zhengbiao , Zhang Min , Ni Haiyan , Ji Ming , Tang Yongzheng , Yang Xiaodi , Long Xiufen , Bi Shuping
Published: March 2004

The voltammetric behavior of α‐ketoglutarate (α‐KG) at the hanging mercury drop electrode (HMDE) has been investigated in acetate buffer solution. Under the optimum experimental conditions (pH 4.5, 0.2 M NaAc‐HAc buffer solution), a sensitive reductive wave of α‐KG was obtained by linear scan voltammetry (LSV) and the peak potential was −1.18 V (vs. SCE), which was an irreversible adsorption wave. The kinetic parameters of the electrode process were α=0.3 and ks=0.72 1/s. There was a linear relationship between peak current ip, α‐KG and α‐KG concentration in the range of 2×10−6–8×10−4 M α‐KG. The detection limit was 8×10−7 M and the relative standard deviation was 2.0% (Cα‐KG=8×10−4 M, n=10). Applications of the reductive wave of α‐KG for practical analysis were addressed as follows: (1) It can be used for the quantitative analysis of α‐KG in biological samples and the results agree well with those obtained from the established ultraviolet spectrophotometric method. (2) Utilizing the complexing effect between α‐KG and aluminum, a linear relationship holds between the decrease of peak current of α‐KG Δip and the added Al concentration C in the range of 5.0×10−6–2.5×10−4 M. The detection limit was 2.2×10−6 M and the relative standard deviation was 3.1% (C=4×10−5 M, n=10). It was successfully applied to the detection of aluminum in water and synthetic biological samples with satisfactory results, which were consistent with those of ICP‐AES. (3) It was also applied to study the effect of AlIII on the glutamate dehydrogenase (GDH) activity in the catalytically reaction of α‐KG+NH$\rm{ {_{4}^{+}}}$+NADH⇌L‐glutamate+NAD++H2O by differential pulse polarography (DPP) technique. By monitoring DPP reductive currents of NAD+ and α‐KG, an elementary important result was found that Al could greatly affect the activity of GDH. This study could be attributed to intrinsic understanding of the aluminum's toxicity in enzyme reaction processes.
Development of a Tubular Sensor Based on a Polypyrrole‐Doped Membrane for the Potentiometric Determination of the Dodecylsulfate Anion in a FIA System
Authors: Álvarez‐Romero Giaan Arturo , Morales‐Pérez Adriana , Rojas‐Hernández Alberto , Palomar‐Pardavé Manuel , Ramírez‐Silva Maria Teresa
Published: March 2004

Potentiostatic polymerization of polypyrrole doped with dodecylsulfate anion (DS−) was carried out in situ over a tubular composite (graphite‐epoxy resin) support in order to develop a potentiometric DS− sensor (TISE) suitable for flow injection analysis (FIA). The sensibility of the TISE was maximized using the SIMPLEX algorithm in terms of the concentration of the pyrrole monomer, the concentration of DS−, the potential imposed and polymerization time. Response times between 2 and 4 minutes were observed. The analytical parameters obtained with the flow system were compared with those obtained in batch studies. In both, flow and batch analysis, potential vs. DS− concentration curves displayed two linear regions with different slopes. Flow analysis for DS− ion brings a total linear range of 1.58×10−5 M to 3.88×10−3 M with a maximum sensibility of 36.4 mV/concentration decade, meanwhile in batch studies the total linear range found was of 6.31×10−6 M to 1.0×10−3 M with a maximum sensibility of 54.49 mV. The flow system response pH range was from 5 to 8. The reproducibility in terms of the relative error of the mean of different experiments was 1.58%. Two salient features of the system designed and built are worthy of mention: the sensor presented high selectivity to the dodecyl sulfate ion as compared to other inorganic anions including other anionic surfactants. The sensor lifetime in the FIA system by means of the sensibility changes was found to be of approximately four months.
Electrochemical Overoxidation of Polyindole and Its Cation‐Permselective Behavior
Authors: Ghita Mihaela , Arrigan Damien W. M.
Published: March 2004

Polyindole films prepared by potentiostatic growth in dichloromethane solution were subjected to overoxidation studies in aqueous media. Overoxidation at potentials greater than 1.1 V (vs. SCE) in 0.1 M KNO3 or 0.1 M H2SO4 was possible. Overoxidation in 0.1 M NaOH resulted in mechanically unstable films which were not adherent to the electrode surface. The overoxidation process in 0.1 M KNO3 involved removal of one electron per four indole monomer moieties in the polymer film. Nucleophilic attack led to introduction of carboxylate functionality and to cation permselective behavior, as tested by cyclic voltammetry and hydrodynamic voltammetry of hexamminoruthenium(III) and hexacyanoferrate(III). Such films may be useful in various electrochemical sensor applications.
Square‐Wave Voltammetric Transfer of Silver Ions Across the Water|1,2‐Dichloroethane Interface
Authors: Sherburn Amanda , Arrigan Damien W. M. , Dryfe Robert A. W. , Boag Neil M.
Published: March 2004

Recently reported studies on the transfer of silver ions across the aqueous|1,2‐dichloroethane interface using cyclic voltammetry (CV), facilitated by organic phase electrolyte anions, have been augmented by square‐wave voltammetry (SWV) and square‐wave stripping voltammetry (SWSV) studies and by consideration of the possible transfers of additional metal cations. Using SWV and SWSV, detection limits have been improved, from the 0.02 mM obtained by CV, to 1.4 μM (SWV) and 2 nM (SWSV). Additional studies show that mercury(I and II) ions, platinum(II) ions and gold(III) ions are also transferable across this interface, to differing extents. Of these three ions studied, highest sensitivity is achieved for the gold species.
Highly Stable Voltammetric Detection of Nitroaromatic Explosives in the Presence of Organic Surfactants at a Polyphenol‐Coated Carbon Electrode
Authors: Wang Joseph , Thongngamdee Sompong , Kumar Arun
Published: March 2004

A polyphenol‐coated screen‐printed carbon electrode is used for highly sensitive voltammetric measurements of the 2,4,6‐trinitrotoluene (TNT) explosive in the presence of surface‐active substances. The permselective/protective polyphenol coating offers excellent resistance to surfactant fouling, while allowing facile transport of the target TNT. High levels of gelatin, humic acid and sodium dodecyl sulfate (SDS) (up to 50 mg/L) have negligible effects upon the square‐wave voltammetric TNT response. The TNT peak current and potential remain nearly the same in the presence of these organic macromolecules, as compared to substantial peak suppressions and shifts at the bare electrode. Control of the electropolymerization time was used for achieving the desired exclusion of interfering surface‐active macromolecules while allowing transport of the target TNT. The response for ppm levels of TNT is highly linear and stable for prolonged operations in the presence of surface‐active substances. By meeting the high sensitivity, selectivity, stability, portability and low‐cost demands, such voltammetric sensing holds great promise for field‐based voltammetric monitoring of nitroaromatic explosive compounds.
Electrochemical Investigation of Binding of Heavy Metal Ions to Turkish Lignites
Authors: Pehlivan Erol , Richardson Amie , Zuman Petr
Published: March 2004

Adsorption and desorption of Cu2+, Pb2+, Cd2+, Ni2+ and Zn2+ ions on samples of lignites (young brown coal) from three areas in the vicinity of Konya (Anatolia, Turkey) were followed using the polarographic method of analysis. This method enables the determination of free metal ions in suspensions containing both small and colloidal particles of lignite. Effects of pH, nature of the metal ion, and origin of the lignite on its adsorption capacity were followed. Binding is only between 5 and 30% reversible, indicating that ion exchange is not the predominant factor. The role of the size and shape of cavities inside pulverized lignite and of the functional groups inside these cavities was considered.