bluuebunny/crossref_metadata_2025 huggingface dataset:
ϵ‐Sarcoglycan immunoreactivity and mRNA expression in mouse brain
Authors: Chan Pokman , Gonzalez‐Maeso Javier , Ruf Frédérique , Bishop David F. , Hof Patrick R. , Sealfon Stuart C.
Published: December 2004

Myoclonus dystonia (M‐D) is a hereditary movement disorder caused by a maternally imprinted gene that is often associated with psychiatric symptoms. Most cases of M‐D are believed to result from mutations of the ϵ‐sarcoglycan protein. The neuroanatomical distribution of ϵ‐sarcoglycan‐like immunoreactivity in mouse was investigated by using an antiserum against the ϵ‐sarcoglycan protein. The expression of ϵ‐sarcoglycan mRNA was studied by a sensitive fluorescence in situ hybridization (FISH) method. Immunohistochemistry and FISH revealed a wide distribution of ϵ‐sarcoglycan protein and mRNA throughout the mouse brain. High expression levels of ϵ‐sarcoglycan mRNA and immunoreactivity were found in the mitral cell layer of the olfactory bulb, the Purkinje cell layer in cerebellum, and the monoaminergic neurons in the mouse midbrain. Immunohistochemistry revealed a similar distribution of ϵ‐sarcoglycan protein. Double‐labeling FISH showed colocalization of tyrosine hydroxylase and ϵ‐sarcoglycan mRNAs within all the midbrain dopaminergic (DAergic) cell groups. By combining FISH with fluorescence immunohistochemistry, coexpression of ϵ‐sarcoglycan mRNA and tryptophan hydroxylase immunoreactivity was found in the serotonergic (5‐HTergic) neurons within the dorsal raphe nucleus. The distribution of ϵ‐sarcoglycan in the mouse brain suggests that the symptom complex of M‐D may be related to the effects of decreased ϵ‐sarcoglycan activity on the development or function of monoaminergic neurons. J. Comp. Neurol. 482:50–73, 2005. © 2004 Wiley‐Liss, Inc.
Distinct expression pattern of insulin‐like growth factor family in rodent taste buds
Authors: Suzuki Yuko , Takeda Masako , Sakakura Yasunori , Suzuki Noriyo
Published: December 2004

The insulin‐like growth factor (IGF) system is an important regulator of growth and differentiation in a variety of tissues. In the present study, the expression of IGF family members in the taste buds of mice and rats was examined. By reverse transcriptase polymerase chain reaction (RT‐PCR) analysis, mRNA of IGF‐I and ‐II, IGF‐I receptor (IGF‐IR), insulin receptor (insulin R), and IGF‐binding protein (IGFBP)‐2, ‐3, ‐4, ‐5, and ‐6 was detected in the taste bud‐containing epithelium of the circumvallate papillae of mice. As suggested by the study using degenerate PCR (McLaughlin [2000] J. Neurosci. 20:5679–5688), IGF‐IR was expressed in most of the taste bud cells of adult mice, as found by immunohistochemistry, and in those of postnatal day (P) 6 mice by in situ hybridization. Insulin R, which has strong homology to IGF‐IR, was also detected in most of the taste bud cells of mice by immunohistochemistry and in situ hybridization. IGF‐I immunoreactivity was detected in a few taste bud cells and in the epithelium surrounding taste buds. Northern blot analysis revealed that the amount of IGF‐I mRNA in taste bud‐containing epithelium was very low compared with that in liver. IGF‐II immunoreactivity was weakly detected in mouse taste buds and the surrounding epithelium. In the rat tissue, a subset of the taste bud cells was positive for IGF‐II. Among the six IGFBPs, IGFBP‐2, ‐5, and ‐6 were detected in the mouse taste buds: IGFBP‐2 and ‐5 immunoreactivity was seen in the majority of the taste bud cells, whereas IGFBP‐6 immunoreactivity was found in the nerve fibers innervating the taste buds. In situ hybridization study also revealed that IGFBP‐2 and ‐5 mRNA was synthesized in the taste buds of P6 mice and that the expression of these mRNAs overlapped in von Ebner's glands. These data reveal that IGF‐I and ‐II might be produced in taste bud cells and (or) surrounding lingual epithelium and act through IGF‐IR and insulin R locally in a paracrine and autocrine manner. The activity of these IGFs may be modulated through their interaction with IGFBP‐2, ‐5, and 6. J. Comp. Neurol. 482:74–84, 2005. © 2004 Wiley‐Liss, Inc.
ZFH4 protein is expressed in many neurons of developing rat brain
Authors: Nogami Shigeharu , Ishii Yoko , Kawaguchi Makoto , Sakata Nobuo , Oya Takeshi , Takagawa Kiyoshi , Kanamori Masahiko , Sabit Hemragul , Obata Toshiyuki , Kimura Tomoatsu , Sasahara Masakiyo
Published: December 2004

The zinc finger‐homeodomain (ZFH) transcription factors contain a zinc finger motif and a homeodomain that might regulate neural and mesenchymal cell differentiation. We have cloned the ZFH4 gene that encodes a protein with structures closely related to ATBF1. In order to study the expression pattern of ZFH4 in the developing rat brain, we raised an antibody against a glutathione‐S‐transferase (GST) fusion protein of ZFH4. Western blotting with this antibody identified a gene product of 390 kDa in the normal rat brain. Levels of the protein were high in the brainstem at embryonic and neonatal periods and in the midbrain and diencephalon in neonatal rat brain. In addition, the corresponding mRNA of 12.5 kb was detected by Northern blotting. An immunolocalization study showed that postmitotic neurons in the brainstem were the major site of ZFH4 expression, and the levels of expression varied depending on age and anatomical sites. Expression was transient and weak in precursor cells at early neurogenesis. Although ZFH4 levels decreased after birth, ZFH4 continued to be expressed in the mature neurons including DOPA decarboxylase‐positive neurons. High levels of expression were also detected in non‐neuronal cells of the subcommissural organ, but the expression was almost undetectable throughout precursor cells to mature neurons in the cerebral cortex and hippocampus. The spatial and temporal expression patterns closely resembled those of ATBF1, and we detected neurons that expressed ZFH4, ATBF1, or both. We postulate that ZFH4 participates in the regulation of neural cell maturation or of region‐specific differentiation of the brain. J. Comp. Neurol. 482:33–49, 2005. © 2004 Wiley‐Liss, Inc.
Spinal cord injury‐induced expression of TrkA, TrkB, phosphorylated CREB, and c‐Jun in rat lumbosacral dorsal root ganglia
Authors: Qiao Li‐Ya , Vizzard Margaret A.
Published: December 2004

Previous studies have demonstrated increased expression and phosphorylation of tyrosine kinase receptor (TrkA, TrkB) in lumbosacral DRG after chronic (6 weeks) spinal cord (T8‐T10) injury. This study examined the effects of acute SCI (48 hours, 2 weeks) on TrkA and TrkB expression and phosphorylation, and CREB and c‐Jun expression in DRG. A significant increase in the number of TrkA‐ (1.5–3‐fold; P ≤ 0.05), TrkB‐ (1.3–2.0‐fold; P ≤ 0.05), and phosphorylated Trk (pTrk)‐immunoreactive (1.5–3‐fold; P ≤ 0.05) cells was observed in the L1, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. A significant increase in the number of phosphorylated (p‐) CREB‐immunoreactive cells was observed in the L1, L2, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. The largest changes in p‐CREB‐immunoreactivity were in L1 and L2 DRG (10‐fold; P ≤ 0.01) at 48 hours after SCI; however, changes were modest in bladder afferent neurons. After SCI, the overall number of c‐Jun‐immunoreactive cells in L1, L2, and S1 DRG was dramatically increased (3–10‐fold; P ≤ 0.01); however, only a low percentage of bladder afferent cells expressed c‐Jun‐IR before or after SCI. In summary, these results suggest that TrkA or TrkB may be involved in reorganization of micturition pathways after SCI. However, CREB or c‐Jun may not be downstream transcription factors in Trk‐mediated signaling cascades in micturition reflex pathways after SCI but may play a role in other, nonbladder SCI‐induced changes. J. Comp. Neurol. 482:142–154, 2005. © 2004 Wiley‐Liss, Inc.
Homogenization of fully nonlinear, uniformly elliptic and parabolic partial differential equations in stationary ergodic media
Authors: Caffarelli Luis A. , Souganidis Panagiotis E. , Wang L.
Published: December 2004

We study the homogenization of fully nonlinear, uniformly elliptic and parabolic second‐order partial differential equations in stationary ergodic media. © 2004 Wiley Periodicals, Inc.
A1 adenosine receptor antagonists, 3‐aryl[1,2,4]triazino[4,3‐a]benzimidazol‐4‐(10H)‐ones (ATBIs) and N‐alkyl and N‐acyl‐(7‐substituted‐2‐phenylimidazo[1,2‐a][1,3,5]triazin‐4‐yl)amines (ITAs): Different recognition of bovine and human binding sites
Authors: Da Settimo Federico , Primofiore Giampaolo , Taliani Sabrina , La Motta Concettina , Novellino Ettore , Greco Giovanni , Lavecchia Antonio , Cosimelli Barbara , Iadanza Manuela , Klotz Karl‐Norbert , Tuscano Daniela , Trincavelli Maria Letizia , Martini Claudia
Published: December 2004

3‐Aryl[1,2,4]triazino[4,3‐a]benzimidazol‐4‐(10H)‐ones (ATBIs) 1 and N‐alkyl and N‐acyl‐(7‐substituted‐2‐phenylimidazo[1,2‐a][1,3,5]triazin‐4‐yl)amines (ITAs) 2, recently reported by us as two novel classes of selective A1 adenosine receptor (A1AR) antagonists using bovine cerebral membranes [Da Settimo et al., 2001, Novellino et al., 2002], were reevaluated for their affinity at human A1, A2A, and A3ARs expressed in CHO cells. All the ATBI derivatives 1 showed similar Ki values in the nanomolar range at both hA1AR and bA1AR, with a good selectivity for the hA1AR over the hA2AAR and hA3AR. The excellent correlation between Ki values at hA1AR and bA1AR in the ATBI series suggests that these compounds interact similarly at the binding sites of the two receptors. Unlike findings for the ATBIs 1, the Ki values of ITAs 2 at the hA1AR and bA1AR do not correlate very well. Several compounds (2g, 2i, 2j, 2m, 2n, and 2r) that bind with a nanomolar affinity to the bA1AR were found to be significantly less potent, or even inactive, at the hA1AR. A comparison of the amino acids in the TM regions involved in the recognition of the ligands at the bA1AR and hA1AR failed to provide a clear explanation of the great differences in ligand affinities between bA1AR and hA1AR. Some hypotheses are advanced to account for these differences. Drug Dev. Res. 63:1–7, 2004. © 2004 Wiley‐Liss, Inc.
Therapeutic effects of CPU 86017 on acute and chronic congestive cardiac failure mediated by reducing ET‐1?NOS and oxidative stress in rats
Authors: Wang Yong‐Qing , Shi Yan‐Ping , Dai De‐Zai
Published: December 2004

CPU 86017, a derivative of berberine, was administered to rats in which acute and chronic heart failure was induced by left coronary artery ligation for 3 h and 8 weeks, respectively. The rats were divided into the following groups: sham operation, coronary artery ligation (CAL), CAL+ CPU 86017 (80?40 and 20 mg/kg, ig) and CAL+ captopril (60 mg/kg, ig). In the acute model, the systolic parameters of LVSP and LV+dp/dtmax as well as the diastolic parameters of LVEDP and LV‐dp/dtmin improved significantly on pretreatment of CPU 86017 (80 mg/kg). Reductions in elevated serum CPK?LDH?MDA?GOT?GPT?infarcted area and blood viscosity were also significant (P < 0.01). In the chronic model, CPU 86017 (80 mg/kg) preserved the systolic parameters of LVSP and LV+dp/dtmax and the diastolic function of the LVEDP and LV‐dp/dtmin. CPU 86017 completely suppressed elevated plasma ANP and ET‐1, serum and tissue iNOS?NO and MDA, whereas the decreased SOD was improved. CPU 86017 and captopril improved cardiac failure performance and regressed cardiac remodeling in CHF by reducing tissue weight index: lung weight/body weight (BW), right ventricular weight/BW, and left ventricular weight/BW. CPU 86017 exerted beneficial actions in cardiac performance in models of both acute and chronic heart failure, mainly by suppressing ET‐1, iNOS, and oxidative stress in infarcted tissue. Drug Dev Res 63:22–32, 2004. © 2004 Wiley‐Liss, Inc.
Expression genomics and cancer drug development
Authors: Liu Edison T.
Published: December 2004

Expression genomics describes the investigation of transcription in a genome‐wide scale, including the study of comprehensive gene regulation. The type of technologies used include microarrays, tag libraries such as serial analysis of gene expression (SAGE), full‐length cDNA cloning and sequencing, chromatin immunoprecipitation coupled with cloning/sequencing or applied to genomic chips [Ruan et al., 2004]. However, since microarrays are the most widely used technology in expression genomics for the study of cancer biology and pharmacology, our discussion will concentrate on studies using expression arrays. Regardless of the methodologies used, information regarding candidate targets, pathways, prognostic markers, and pharmacodynamic responses can be extracted from these experiments. Our premise is that these are powerful tools that can accelerate target identification, validation, and therefore drug discovery. Optimizing this potential will require a different approach to experimental design. Drug Dev. Res. 62:295–302, 2004. © 2004 Wiley‐Liss, Inc.
A new model for utilising chemical diversity from natural sources
Authors: Buss Antony D. , Butler Mark S.
Published: December 2004

Although combinatorial chemistry technology has enabled large libraries of compounds to be screened for biological activity and synthetic modifications to be effected rapidly, the reality is that quality leads and development candidates for many drug targets still prove difficult to find. This is particularly relevant to antiinfective, oncology, and immunomodulation targets and also those involving protein–protein interactions. In the past, natural products have led to excellent drugs for precisely these therapeutic areas, but the difficulties of identifying and utilising such compounds compared to less complex molecules synthesised using combinatorial chemistry techniques then led many to question their value in modern‐day drug discovery. In fact, in the early 1990s, a significant number of pharmaceutical companies reduced or even terminated the natural product‐based drug discovery activities that had served them so well in the past. Nevertheless a renaissance appears to be at hand. The pressing need to fill drug development pipelines, combined with attractive outsourcing opportunities, have prompted many of the very same companies to reevaluate the utility of natural products as sources of novel drug leads. Through a judicious combination of new technologies and compelling business model, at least one Singapore‐based company is offering cost‐effective solutions for accessing the unique chemical diversity found in Nature. Drug Dev. Res. 62:362–370, 2004. © 2004 Wiley‐Liss, Inc.
Translating the Genome into individualized therapeutics
Authors: Lavedan Christian , Birznieks Gunther , Dressman Marlene , McCullough Karen , Paczkowski Rebecca , Torres Rosa , Wolfgang Curt , Polymeropoulos Mihael
Published: December 2004

The successful completion of the Human Genome Project marked a culmination of numerous advances in genetic research and is viewed as a significant turning point in biology and medicine. Many aspects of medicine and health care may be directly affected by the unraveling of the human genome, including the development of new drugs. Genetic and genomic technologies are being implemented in pharmaceutical and biotechnology companies in search of a competitive advantage in the continual race to discover new therapeutics and bring them to market. These companies are expecting the technologies to enable them to more quickly obtain valuable information on the etiology of diseases, the mechanism of drug action, and treatment response. Successful examples of the implementation of pharmacogenetics and pharmacogenomics have already emerged from the “genome revolution.” The spread of genetic and genomic knowledge throughout all phases of drug development should lead to the successful development of individualized, safer, and more efficacious therapeutics. Ideally, such drugs will maximize therapeutic effects and improve patients' overall quality of life. Drug Dev. Res. 62:371–382, 2004. © 2004 Wiley‐Liss, Inc.
Shape‐mimetics of G‐protein‐coupled receptors in therapeutic drug design and screening
Authors: Sadler Kristen , Tam James P.
Published: December 2004

Cell surface receptors containing multiple transmembrane (TM) bundles have posed constraints for stable expression of soluble proteins by recombinant methods but created opportunities for synthesis by chemical approaches. The structural restraints imposed by the TM bundles form extracellular loops that can be mimicked by end‐to‐end cyclic peptides. In this paper, we describe an enabling technology that has been designed to exploit a chemical approach for development of cell surface receptor‐mimetics that couple with phage‐display library to obtain biologically active single‐chain antibodies (ScFvs) by an efficient screening method. This approach has been successful in the selection and purification of ScFvs against CCR5, a chemokine receptor critical to HIV infectivity, and holds promise for drug development against other G‐protein‐coupled receptors, including orphan receptors, as well as other receptor proteins anchored by multiple TM helices to the cell surface. Drug Dev. Res. 62:336–348, 2004. © 2004 Wiley‐Liss, Inc.
PLK1 as a potential drug target in cancer therapy
Authors: Goh Kee Chuan , Wang Haishan , Yu Niefang , Zhou Yifa , Zheng Yin , Lim ZeYi , Sangthongpitag Kanda , Fang Lijuan , Du Mark , Wang Xukun , Jefferson A. B. , Rose Janet , Shamoon Blanche , Reinhard Christoph , Carte Brad , Entzeroth Michael , Ni BinHui , Taylor Marcia L. , Stünkel Walter
Published: December 2004

Polo‐like kinase 1 (PLK1) has been shown to be involved in cell cycle progression of rapidly proliferating, nontransformed cells as well as tumor cells. In cancer, overexpression of PLK1 contributes to the malignant state by aberrant cell cycle regulation at the G2/M phase. We attempted to validate PLK1 function in cell‐based assays using antisense oligonucleotide knockout approaches. Our own results and published findings of other groups have led to the conclusion that PLK1 is a logical point for pharmacological intervention. HTS campaigns performed against the recombinant PLK1‐protein led to the identification of two PLK1 inhibitory scaffolds, one containing a 7‐azapteridine ring system, the other a fused tetracyclic ketone system. These compounds showed low micromolar antiproliferative activity towards SW620, a human colon cancer cell line, most likely through cell cycle arrest at the G2/M phase. Our data suggest that PLK1 may serve as a target for discovering small molecule anticancer agents. Drug Dev. Res. 62:349–361, 2004. © 2004 Wiley‐Liss, Inc.
New technologies for vaccine development
Authors: Srinivasan Kellathur N. , Brusic Vladimir , August Thomas J.
Published: December 2004

Vaccines offer protection against infectious diseases, but the successes from the years of development have been mixed. Some diseases have been effectively controlled or eradicated through vaccination, whereas treatments for a number of diseases, especially the reemerging diseases, currently do not exist. Improved understanding of pathogen variability as well as of the diversity of the human immune system, plus technological advances in genetic and molecular biology provide better insights in the host–pathogen interaction and new avenues for vaccine development. In this article we discuss the latest trends in vaccine research with focus on epitope‐based DNA vaccines and trafficking components for efficient vaccine delivery. These approaches are promising in dealing with host and pathogen diversity as well as with diversity within human populations. Drug Dev. Res. 62:383–392, 2004. © 2004 Wiley‐Liss, Inc.
Novel Model Sulfur Compounds as Mechanistic Probes for Enzymatic and Biomimetic Oxidations
Authors: Peñéñory Alicia B. , Argüello Juan E. , Puiatti Marcelo
Published: December 2004

To test for the intermediacy of sulfide radical cations in biomimetic and enzymatic oxidations, the sulfides PhSCH3 (1a), PhSCH2Ph (1b), PhSCHPh2 (1c), PhSCPh3 (1d), CH3SCHPh2 (2), PhSCH2CH=CH2 (3), PhSCH2CH=CHPh (4) and CH3SCH2CH=CHPh (5) were studied, and their results were compared to those obtained for the corresponding chemical electron transfer (CET) and photoinduced electron transfer (PET) oxidations. The radical cations generated from 3−5 by CET in the presence of cerium(IV) ammonium nitrate (CAN) yielded only fragmentation products from the alkyl cations and the thiyl radicals (RS·), whereas 2·+ afforded both fragmentation and mainly α‐deprotonation products. Photochemical treatment of the sulfides 1a and 1b with C(NO2)4 gave only the corresponding sulfoxides, while fragmentation was the main pathway for the photoreactions of 1c, 2 and 5, and for 1d only this latter process was observed. These results support our selection of the sulfides RSCHPh2, RSCH2CH=CHPh (R = Me, Ph) and PhSCPh3 as models for the biomimetic and enzymatic studies. As evidenced by the sulfoxides and sulfones detected as unique products both in protic and in aprotic solvents, it is proposed that the mechanism of the biomimetic sulfoxidations of sulfides 1c and 2−5 by TPPFeIIICl is direct oxygen transfer. Three enzymes − Coprinus cinereus peroxidase (CiP), horseradish peroxidase (HRP) and chloroperoxidase (CPO) − were studied in the oxidation of sulfides 1a, 2, 4 and 5. The use of a racemic alkyl hydroperoxide in the CiP enzymatic oxidation of sulfides 5 and 2 yielded the corresponding sulfoxides (23 and 29%) and the aldehyde or benzophenone (5%), respectively. These results suggest the involvement of an ET process for the CiP‐catalysed oxidation. Fragmentation products were observed in the enzymatic oxidation of sulfide 4 with HRP, which confirms the previously proposed ET mechanism. On the other hand, the CPO‐enzymatic oxidation of sulfide 5 yielded only the corresponding sulfoxide, as would be expected for a direct oxygen‐transfer or oxene mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Characterization, and Thermal Behavior of Steroidal Dendrons
Authors: Ropponen Jarmo , Tamminen Jari , Lahtinen Manu , Linnanto Juha , Rissanen Kari , Kolehmainen Erkki
Published: December 2004

A series of novel dendritic steroidal polyesters of first and second generation has been synthesized in convergent fashion by the use of 2,2‐bis(hydroxymethyl)propionic acid as a repeating unit. The first‐ and second‐generation hydroxy‐functionalized dendrons with a variety of surface modifications were produced through the use of four bile acids: lithocholic acid (LCA), ursodeoxycholic acid (UDCA), deoxycholic acid (DCA), and cholic acid (CA). The thermal behavior of the steroidal dendrons was characterized by differential scanning calorimetry (DSC) and by thermogravimetric analysis (TGA). Finally, quantum chemical calculation methods were used to study the geometries of the dendrons and the occurrence of intramolecular hydrogen bonds in these dendritic molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Photochromism of Dithienylethenes Containing Fluorinated Thiophene Rings
Authors: Higashiguchi Kenji , Matsuda Kenji , Asano Yukako , Murakami Akinori , Nakamura Shinichiro , Irie Masahiro
Published: December 2004

Bis(3‐thienyl)perfluorocyclopentenes containing partially fluorinated thiophene rings were synthesized and their behaviors examined. Dithienylethenes containing chlorinated thiophene rings were also prepared as reference compounds. The absorption maxima of the closed‐ring isomers, their thermal stabilities, and their quantum yields varied depending on the substitution position. The absorption maxima showed a red shift upon fluorine substitution at the 2‐ or 4‐positions of the thiophene ring, whereas a blue shift was observed upon substitution at the 5‐position. This shift was explained by the shape of the HOMO and LUMO and was well reproduced by theoretical calculations using time‐dependent density‐functional theory (TD‐DFT). The cycloreversion quantum yield of the closed‐ring isomer of 2‐fluorine‐substituted 1,2‐bis(2‐fluoro‐3‐thienyl)perfluorocyclopentene was about 130 times smaller than that of the closed‐ring isomer of 5‐fluorine‐substituted 1,2‐bis(5‐fluoro‐2‐methyl‐3‐thienyl)perfluorocyclopentene. This low quantum yield was attributed to the change of the π‐conjugation mode in the closed‐ring isomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
In Search of the Weak, Six‐Membered Intramolecular Hydrogen Bond in the Solution and Solid States of Guanidinobenzimidazole
Authors: Chen Jing , Willis Peter G. , Parkin Sean , Cammers Arthur
Published: December 2004

The chemical literature presents evidence for the nonexistence of the intramolecular hydrogen bond in neutral 2‐guanidinobenzimidazole, a result that defies chemical intuition. In the current study, analyses of substituted 2‐guanidinobenzimidazoles by dynamic 1H NMR, IR, and X‐ray diffraction unveiled the contribution of the intramolecular hydrogen bond to the overall structure and conformational equilibria. The presence of the intramolecular hydrogen bond in this work and its absence in previous studies of the unsubstituted parent compound is reconciled by the fact that intramolecular hydrogen bonds between the imidazole moieties and guanidino NH2 protons were weak. The intramolecular hydrogen bonds were more apparent in derivatives with guanidino NHR. The behavior of the latter indicated competition between and coexistence of inter‐ and intramolecular hydrogen bonding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
(Trialkoxysilyl)tetrathiafulvalenes: Precursors of Organized Organic‐Inorganic Hybrid Materials by Sol‐Gel Chemistry
Authors: Bellec Nathalie , Lerouge Frédéric , Pichon Benoît , Cerveau Geneviève , Corriu Robert J. P. , Lorcy Dominique
Published: December 2004

The synthesis, characterization and electrochemical behaviour of novel monomers for use in sol‐gel processes are described. These new compounds include a rigid tetrathiafulvalene (TTF) core substituted by one or two spacers, to which a triethoxysilyl group is covalently bonded. The synthesis is based on the preparation of various cyanoethyl‐protected TTF thiolates, deprotection and alkylation of thiolate with 2‐bromoethanol, and subsequent condensation of the alcohol function with 3‐(triethoxysilyl)propyl isocyanate. The donor ability of the title compounds has been investigated by electrochemical studies. The hydrolytic polycondensation of these new precursors was performed in THF solution in the presence of nucleophile (tetrabutylammonium fluoride, TBAF) or acid (HCl) catalysts. The resulting hybrid solids are highly polycondensed and present organization at both the nanometric (X‐ray diffraction) and micrometric (birefringence) scales. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stereoselective Synthesis of 1,2,3‐Trisubstituted 1,3‐Dienes through Novel [3,3]‐Sigmatropic Rearrangements in α‐Allenic Methanesulfonates: Application to the Preparation of Fused Tricyclic Systems by Tandem Rearrangement/Diels−Alder Reaction
Authors: Alcaide Benito , Almendros Pedro , Aragoncillo Cristina , Redondo María C.
Published: December 2004

An unprecedented stereoselective and general synthesis of 1,2,3‐trisubstituted 1,3‐dienes from α‐allenols just by treatment with a methanesulfonyl chloride/tertiary amine system has been developed. This transformation might be tentatively explained in terms of a migration of the methanesulfonyl group in the initially formed α‐allenic methanesulfonate to give the corresponding mesyloxy‐diene through a [3,3]‐sigmatropic rearrangement. This reactivity pattern was incorporated into a domino process, allowing the development of a novel one‐pot synthetic strategy for the preparation of fused tricycles from monocyclic allenols, masked functionalized dienes, when subjected to a domino allenol transposition/intramolecular Diels−Alder reaction process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Theoretical ab initio Study of the Capacity of Several Binding Units for the Molecular Recognition of Anions
Authors: Garau Carolina , Frontera Antonio , Ballester Pablo , Quiñonero David , Costa Antoni , Deyà Pere M.
Published: December 2004

Noncovalent bonding between anions and the π‐cloud of electron‐deficient aromatic rings has recently attracted considerable attention. Complexes of bromide with different electron‐deficient aromatic rings and with other binding units based on hydrogen bonding (urea, thiourea and squaramide) have been studied and compared using high level B3LYP/6‐31++G** ab initio and Molecular Interaction Potential with polarization (MIPp) calculations. Our findings reveal that electron‐deficient aromatic rings are excellent candidates for constructing anion receptors and that the interaction strength can be modulated by the nature of the ring. Supporting experimental evidence has been obtained from X‐ray structures retrieved from the Cambridge Structural Database. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Formal [3 + 3] Cycloaddition Approach to Natural‐Product Synthesis
Authors: Hsung Richard P. , Kurdyumov Aleksey V. , Sydorenko Nadiya
Published: December 2004

A formal [3 + 3] cycloaddition strategy for constructing complex heterocycles is reviewed here. This formal cycloaddition involves condensation of α,β‐unsaturated iminium salts with 1,3‐dicarbonyl equivalents. These reactions consist of a Knoevenagel‐type condensation followed by a reversible 6π‐electron electrocyclic ring‐closure. They constitute a stepwise formal [3 + 3] cycloaddition protocol with the net result being the formation of two σ‐bonds in addition to a new stereocenter adjacent to the heteroatom. This review describes in some detail, but not comprehensively, some precedents, problems, solutions, and stereochemical mechanistic issues, and focuses on applications of this formal cycloaddition strategy in natural product synthesis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Aquapalladium Complex: A Stable and Convenient Catalyst for the Intermolecular Hydroamination of Alkynes
Authors: Shimada Tomohiro , Bajracharya Gan B. , Yamamoto Yoshinori
Published: December 2004

The intermolecular hydroamination of alkynes proceeds very smoothly in the presence of a catalytic amount of the aquapalladium complex [Pd(dppe)(H2O)2](TfO)2. This reaction most probably proceeds through the formation of an equilibrium between the hydroxopalladium and the amidopalladium complexes, and subsequent aminopalladation of alkynes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The Structures and Thermodynamics of Complexes between Water‐Soluble Calix[4]arenes and Dipyridinium Ions
Authors: Liu Yu , Guo Dong‐Sheng , Yang En‐Cui , Zhang Heng‐Yi , Zhao Yan‐Li
Published: December 2004

Three crystalline complexes were prepared by the inclusion complexation of p‐sulfonatothiacalix[4]arene (TCAS) and p‐sulfonatocalix[4]arene (CAS) with 2,2′‐dipyridinium (2‐DPD; (complexes 1 and 2, respectively), and TCAS with 4,4′‐dipyridinium (4‐DPD; complex 3). The crystal structures show that the calixarenes in 1 and 2 maintain their original cone conformation, with shallow inclusion of 2‐DPD, and assemble themselves into bi‐layer arrangements. However, the cone shape of TCAS in 3 is disrupted by 4‐DPD to assume the so‐called 1,2‐alternate conformation in the solid state, which is similar to the 1,3‐alternate case of CAS stabilized by 4‐DPD (4). The thermodynamics of this inclusion complexation were further investigated by microcalorimetric titration in aqueous solution. The obtained results indicated that the molecular binding ability and selectivity of TCAS/CAS with DPDs is entirely controlled by enthalpy gains accompanied by a smaller negative entropic change; these are discussed from the viewpoint of electrostatic, hydrogen‐bonding, π‐stacking, and van der Waals interactions, size/shape‐fit, and a desolvation effect between host and guest. The molecular selectivity for the inclusion complexation of 2‐DPD with CAS was found to be nine times greater than that of 4‐DPD with CAS. Combining the present crystal structures and thermodynamic parameters revealed that the position of the nitrogen atoms in the DPDs is the crucial factor for controlling the binding modes, molecular selectivity, conformational features, and assembly behavior of the host upon complexation with TCAS/CAS. This will help us to design large molecular assemblies possessing highly supramolecular architectures based on calixarenes by controlling exactly the guest molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
On the Mechanism of the Reductive Metallation of Asymmetrically Substituted Silyl Chlorides
Authors: Oestreich Martin , Auer Gertrud , Keller Manfred
Published: December 2004

An investigation of the stereochemical course of the reductive metallation of silyl chlorides with silicon‐centred chirality has revealed two major events which are detrimental to stereoselection during silyl anion formation: (1) chloride‐induced racemisation of silyl chlorides and (2) nonstereoselective formal dimerisation during metallation providing the corresponding disilane. In control experiments, the stereochemical course of these processes has been independently verified for the reductive metallation of the enantioenriched cyclic silyl chloride (SiS)‐7a(R = H,er⩾ 88:12). A screening of several related derivatives of (SiS)‐7aled to the sterically encumbered silyl chloride (SiR)‐7c(R =iPr,er⩾ 94:6) which displays some unique features. This structural modification prevents racemisation by lithium chloride (T< −40 °C) as well as dimerisation (T< −100 °C) thus allowing for the first generation of an asymmetrically substituted silyl anion (SiS)‐8c(er= 74:26) by reductive metallation of a silyl chloride with silicon‐centred chirality. Moreover, the enantiospecificity of the preparation of (SiR)‐7cby chlorination [(SiS)‐9c→ (SiR)‐7c] and its reduction with aluminium hydrides [(SiR)‐7c→ (SiR)‐9c] have been unambiguously determined by X‐ray crystallography as retention (⩾99%) and inversion (⩾99%), respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Ring‐Closing Metathesis Dimerizations of Enynes and Deprotections of Propargyl Ethers Mediated by Carbene Ruthenium Complexes
Authors: Hahn Dong‐Woo , Byun Dong‐Min , Tae Jinsung
Published: December 2004

The ring‐forming dimerizations of enynes were catalyzed by the first‐generation carbene ruthenium complex, and the effects of the catalysts and ethylene gas were studied. The deprotection of propargyl ethers by the carbene ruthenium complexes is the first to be reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Simple Route to a Pyridinyl[2.2]paracyclophane
Authors: Hopf Henning , Aly Ashraf A. , Swaminathan Vijay Narayanan , Ernst Ludger , Dix Ina , Jones Peter G.
Published: December 2004

4‐Acetyl[2.2]paracyclophane (1) is converted into the nitrone 2 by treatment with N‐methylhydroxylamine·hydrochloride. When 2 is reacted with (E)‐1,2‐dibenzoylethene (4) the pyridinyl[2.2]paracyclophane 13 is formed in a novel condensation reaction. The structures of 2 and 13, and the mechanism of formation of the latter are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
On‐Line Monolithic Enzyme Reactor Fabricated by Sol‐Gel Process for Elimination of Ascorbic Acid While Monitoring Dopamine
Authors: Chen Zilin , Hayashi Katsuyoshi , Iwasaki Yuzuru , Kurita Ryoji , Niwa Osamu , Sunaawa Kenji
Published: December 2004

Catecholamine, a well‐known neurotransmitter, is released to restore heart function after the occurrence of cardiac ischemia. Endogenous ascorbic acid interferes considerably with the monitoring of neurotransmitters such as catecholamine and glutamate. In this work we have successfully developed a nanoliter volume monolithic enzyme reactor and integrated it with a carbon film electrode for monitoring dopamine in order to scavenge such electroactive interferents as ascorbic acid. A monolithic silica support prepared by the sol‐gel process has a large through‐pore structure and a nanoporous surface. The low back pressure resulting from the large though‐pore structure makes it possible to immobilize the enzyme and introduce fluid into the flow monitoring system by using a microsyringe pump. Ascorbate oxidase (AOx) was immobilized on the nanoporous surface of a monolithic matrix by physical adsorption and used for converting the ascorbic acid into its electrochemically inert form, dehydroascorbic acid, while monitoring dopamine. We showed that more than 99.8% of 100 μM of ascorbic acid could be converted to its oxidized form in the monolithic enzyme reactor. We succeeded in monitoring dopamine at a concentration of less than 100 nM in the presence of 50 μM of ascorbic acid. Therefore, this work demonstrated that a monolithic silica support offers excellent potential in regards to realizing a highly selective enzymatic reactor for biosensors.
Computational Electrochemistry: A Model to Studying Ohmic Distortion of Voltammetry in Multiple Working Electrode, Microfluidic Devices, an Adaptive FEM Approach
Authors: Henley Iain , Fisher Adrian
Published: December 2004

Characteristics of mass transport and potential distribution applicable to microfluidic electrochemical flow cell devices has been modelled using the finite element method. A flexible, automatic grid generation algorithm has been combined with an a‐posteriori error indication technique presented by Nann and Heinze to allow irregular cell geometries to be modelled. The code has been applied to the problem of steady state generator – detector linear sweep voltammetry in a channel flow cell showing the effects of IR drop on the voltammetric response of each electrode.
Preparation of Thallium Hexacyanoferrate Film and Mixed‐Film Modified Electrodes with Cobalt(II) Hexacyanoferrate
Authors: Chen Shen‐Ming , Peng Kuo‐Tzu , Lin Kuo‐Chiang
Published: December 2004

Thallium hexacyanoferrate films have been prepared from various aqueous electrolyte solutions using consecutive cyclic voltammetry. The cyclic voltammograms recorded the direct deposition of thallium hexacyanoferrate films from the mixing of Tl3+ and [Fe(CN)6]3− ions from solutions of seven cations: Li+, Na+, K+, Rb+, Cs+, H+, and Tl+. An electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the thallium hexacyanoferrate films. The thallium hexacyanoferrate film shows a single redox couple with a formal potential between +0.6 V and +1.2 V, and shows a cation effect (H+, Li+, Na+, K+, Rb+, Cs+, and Tl+). A mixed film and a two‐layered modified electrodes composed of a thallium hexacyanoferrate film with cobalt(II) hexacyanoferrate film were prepared.
Simultaneous Determination of Hydroquinone and Catechol at a Glassy Carbon Electrode Modified with Multiwall Carbon Nanotubes
Authors: Qi Honglan , Zhang Chengxiao
Published: December 2004

A simply and high selectively electrochemical method for simultaneous determination of hydroquinone and catechol has been developed at a glassy carbon electrode modified with multiwall carbon nanotubes (MWNT). It was found that the oxidation peak separation of hydroquinone and catechol and the oxidation currents of hydroquinone and catechol greatly increase at MWNT modified electrode in 0.20 M acetate buffer solution (pH 4.5). The oxidation peaks of hydroquinone and catechol merge into a large peak of 302 mV (vs. Ag/AgCl, 3 M NaCl) at bare glassy carbon electrode. The two corresponding well‐defined oxidation peaks of hydroquinone in the presence of catechol at MWNT modified electrode occur at 264 mV and 162 mV, respectively. Under the optimized condition, the oxidation peak current of hydroquinone is linear over a range from 1.0×10−6 M to 1.0×10−4 M hydroquinone in the presence of 1.0×10−4 M catechol with the detection limit of 7.5×10−7 M and the oxidation peak current of catechol is linear over a range from 6.0×10−7 M to 1.0×10−4 M catechol in the presence of 1.0×10−4 M hydroquinone with the detection limit of 2.0×10−7 M. The proposed method has been applied to simultaneous determination of hydroquinone and catechol in a water sample with simplicity and high selectivity.
Highly‐Sensitive Determination of 6‐Mercaptopurine and Its Metabolites by Electrochemical Reductive Desorption Measurements
Authors: Sato Yukari , Ishikawa Yayoi , Matsuura Hiroaki , Uosaki Kohei , Mizutani Fumio , Niwa Osamu
Published: December 2004

The electrochemical detection of 6‐mercaputopurine (6‐MP), which is one of the most well‐known drugs of antimetabolites, and its analogues was studied. The presented method is based on chemisorption (accumulation)/desorption processes of drugs onto/from the Au electrode surface. Using this method, we succeeded in detecting 6‐MP even in very diluted solution (concentration of 6‐MP: 1×10−8 M). The lower detection limit of 6‐MP was considerably improved compared with the previous HPLC studies by using our proposed system. Desorptive potentials of 6‐MP‐metabolites and its analogues were different from those of 6‐MP. This provides the possibility of simultaneous detection of 6‐MP and its typical metabolites.
Catastrophic precipitation‐triggered lahar at Casita volcano, Nicaragua: occurrence, bulking and transformation
Authors: Scott Kevin M. , Vallance James W. , Kerle Norman , Luis Macías Jose , Strauch Wilfried , Devoli Graziella
Published: December 2004

A catastrophic lahar began on 30 October 1998, as hurricane precipitation triggered a small ﬂank collapse of Casita volcano, a complex and probably dormant stratovolcano. The initial rockslide‐debris avalanche evolved on the ﬂank to yield a watery debris ﬂood with a sediment concentration less than 60 per cent by volume at the base of the volcano. Within 2·5 km, however, the watery ﬂow entrained (bulked) enough sediment to transform entirely to a debris ﬂow. The debris ﬂow, 6 km downstream and 1·2 km wide and 3 to 6 m deep, killed 2500 people, nearly the entire populations of the communities of El Porvenir and Rolando Rodriguez. These ‘new towns’ were developed in a prehistoric lahar pathway: at least three ﬂows of similar size since 8330 14C years bp are documented by stratigraphy in the same 30‐degree sector. Travel time between perception of the ﬂow and destruction of the towns was only 2·5–3·0 minutes. The evolution of the ﬂow wave occurred with hydraulic continuity and without pause or any extraordinary addition of water.

The precipitation trigger of the Casita lahar emphasizes the need, in volcano hazard assessments, for including the potential for non‐eruption‐related collapse lahars with the more predictable potential of their syneruption analogues. The ﬂow behaviour emphasizes that volcano collapses can yield not only volcanic debris avalanches with restricted runouts, but also mobile lahars that enlarge by bulking as they ﬂow. Volumes and hence inundation areas of collapse‐runout lahars can increase greatly beyond their sources: the volume of the Casita lahar bulked to at least 2·6 times the contributing volume of the ﬂank collapse and 4·2 times that of the debris ﬂood. At least 78 per cent of the debris ﬂow matrix (sediment < −1·0Φ; 2 mm) was entrained during ﬂow. Copyright © 2004 John Wiley & Sons, Ltd.
Studies on essential oils, Part 42: chemical, antifungal, antioxidant and sprout suppressant studies on ginger essential oil and its oleoresin
Authors: Singh Gurdip , Maurya Sumitra , Catalan C. , de Lampasona M. P.
Published: December 2004

GC–MS analysis of fresh rhizome essential oil of Zingiber ofﬁcinale showed the presence of 69 components, accounting for 96.93% of the total oil. The major component was α‐zingiberene (28.62%) followed by camphene (9.32%), ar‐curcumene (9.09%) and β‐phellandrene (7.97%). Analysis of the oleoresin showed the presence of 34 components, accounting for 88.63% of the total oleoresin. The major components were trans‐6‐shogaol (26.23%), trans‐10‐shogaol (13.0%), α‐zingiberene (9.66%) and 10‐gingerdione (6.80%). Moreover, the essential oil was found to be 100% antifungal against Fusarium oxysporum, whereas the oleoresin was 100% antifungal against Aspergillus niger. The latter expressed better antioxidant activity in sunﬂower oil as compared to the essential oil and synthetic antioxidants (BHA and BHT). Copyright © 2004 John Wiley & Sons, Ltd.
Volatile constituents and antioxidant activity of essential oils from Lippia multiﬂora Mold. growing in Gabon
Authors: Agnaniet Huguette , Makani Thomas , Akagah Aristide , Menut Chantal , Bessière Jean Marie
Published: December 2004

The leaf essential oils from two samples of Lippia multiﬂora (Verbenaceae) collected in two localities of Gabon were obtained by hydrodistillation and analysed by GC and GC‐MS. The oils differed completely in their chemical composition: the former was characterized by a high amount of ipsdienone (54.6%), (Z)‐ and (E)‐ocimenones (20.3%); (E)‐β‐farnesene (7.4%) and β‐caryophyllene (4.6%) were the main components of the sesquiterpenoid fraction; the latter consisted mainly of thymol (41.9%), thymyl acetate (21.2%), p‐cymene (9.8%) and carvacrol (7.2%), which allows differenciation between two chemotypes. The antioxidant and antiradical activities of both samples were evaluated comparatively to those of reference compounds (BHT, thymol and carvacrol). An interesting antioxidant activity was found for the second chemotype as expected on the basis of its phenolic compounds content. Copyright © 2004 John Wiley & Sons, Ltd.
Essential oil composition from some plant parts of Conyza bonariensis (L.) Cronquist
Authors: Barbosa Luiz C. A. , Paula Vanderlúcia F. , Azevedo Anelisa S. , Silva Eldo A. M. , Nascimento Evandro A.
Published: December 2004

The essential oils from the roots, leaves, stems and inﬂorescences of Conyza bonariensis L. were investigated. A total of 17 constituents were identiﬁed by GC‐MS, including monoterpenes, acetylenes, sesquiterpenes and diterpenes. The major constituents were matricaria methyl ester (roots, 74.4%), limonene (leaves, 29.6%), manool (stems, 25.3%) and carvone (inﬂorescences, 21.1%). Copyright © 2004 John Wiley & Sons, Ltd.
Chemical composition and antimicrobial activity of the essential oil of Acinos arvensis (Lam.) Dandy from Serbia
Authors: Jovanovic Tatjana , Kitic Dusanka , Palic Radosav , Stojanovic Gordana , Ristic Mihailo
Published: December 2004

The hydrodistilled essential oil of Acinos arvensis (Lam.) Dandy was analysed by GC and GC/MS. Thirty constituents representing 83.8% of the oil were identiﬁed, of which germacrene D (47.0%) was the major component. Furthermore, β‐bourbonene (7.7%), caryophyllene oxide (3.2%) and β‐caryophyllene (3.0%) were noted as additional signiﬁcant constituents. The antimicrobial activity of the oil was screened against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. All the microorganisms, except for Pseudomonas aeruginosa, were found to be susceptible to the oil. Copyright © 2004 John Wiley & Sons, Ltd.
Composition and antimicrobial activity of the essential oil of Achillea falcata L. (Asteraceae)
Authors: Senatore Felice , Napolitano Francesco , Apostolides Arnold Nelly , Bruno Maurizio , Herz Werner
Published: December 2004

The composition of the essential oil from aerial parts of Achillea falcata L. (Asteraceae) growing wild in Lebanon was analysed by GC and GC–MS; 58 compounds, representing 94.4% of the oil, were identiﬁed. Isomers of the cyclobutane ethanol, 1‐methyl‐2‐(1‐methylethenyl), grandisol (21.4%) and fragranol (16.8%) were the main components of the oil. Also abundant were artemisia ketone (5.2%), terpinen‐4‐ol (4.5%) and 1,8‐cineole (4.0%). The essential oil shows inhibitory activity mainly against Gram‐positive bacteria. Copyright © 2004 John Wiley & Sons, Ltd.