bluuebunny/crossref_metadata_2025 huggingface dataset:
Homooxacalixarenes. Part 2. Receptor Properties
Authors: Shokova E. A. , Kovalev V. V.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Anthracenedione Analogues — Synthesis and Biological Activity
Authors: Dzierzbicka K. , Kolodziejczyk A. M.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Ruthenium‐Catalyzed Organic Synthesis in Aqueous Media
Authors: Wang Mingwen , Li Chao‐Jun
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Oxidation Using Ruthenium Catalysts
Authors: Arends I. W. C. E. , Kodama T. , Sheldon R. A.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Ruthenium‐Catalyzed Synthesis of Heterocyclic Compounds
Authors: Yamamoto Yoshihiko , Itoh Kenji
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Silicon Derivatives with Ruthenium Catalysts
Authors: Marciniec Bogdan , Pietraszuk Cezary
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Selective Carbonylations with Ruthenium Catalysts
Authors: Chatani Naoto
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Ruthenium Vinylidenes and Allenylidenes in Catalysis
Authors: Bruneau Christian
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Recent Advances in Alkene Metathesis
Authors: Connon Stephen J. , Blechert Siegfried
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
The Reactivity of Platinum Complexes Containing Hemilabile Ligands Towards Silanes and Stannanes
Authors: Stohr Frank , Thompson Susan , Sturmayr Dietmar , Pfeiffer Jurgen , Schubert Ulrich
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Catalytic Activity of Rhodium‐Siloxide Complexes in Hydrosilylation of Allyl Ethers and Allyl Esters
Authors: Marciniec Bogdan , Walczuk Edyta , Blazejewska‐Chadyniak Paulina , Chadyniak Dariusz , Kujawa‐Welten Malgorzata , Krompiec Stanislaw
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Novel Cyclic and Polycyclic Chalcogenides of Silicon
Authors: Herzog Uwe , Boehme Uwe , Rheinwald Gerd
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Cyclocarbamation Reactions of Olefinic Compounds, Epoxides and Aziridines
Authors: Gonzalez‐Rosende M. Eugenia , Zaballos‐Garcia Elena , Sepulveda‐Arques Jose , Orena Mario
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Recent Applications of Proazaphosphatranes in Organic Synthesis
Authors: Verkade John G. , Kisanga Philip B.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Domino Reactions in the Synthesis of Heterocyclic Natural Products and Analogues
Authors: Tietze Lutz F. , Rackelmann Nils
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Total Synthesis Highlights
Authors: Clarke Paul A. , Cridland Andrew P.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Sequential Stereoselective Oxidations: Simple Routes to Enantiomeric γ‐Hydroxy Sulfoxides
Authors: Skarzewski Jacek
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
New π‐Delocalized Persistent Radicals
Authors: Kaszynski Piotr
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Time‐Resolved Spectroscopy of the Dynamics of Photoinduced Ionic‐to‐Neutral Phase Transition in Tetrathiafulvalen‐p‐chloranil Crystals
Authors: Tanimura Katsumi
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
(−)‐Clausenamide potentiates synaptic transmission in the dentate gyrus of rats
Authors: Xu Lin , Liu Shao‐Lin , Zhang Jun‐Tian
Published: April 2005

The effect of clausenamide on synaptic transmission in the dentate gyrus of rats in vivo and its possible mechanism of action were investigated in this study. Four of 16 enantiomers showed potentiating effects on basal synaptic transmission in anesthetized animals. By comparing one pair of enantiomers, (−)‐clausenamide and (+)‐clausenamide, we can report three primary findings: (1) (−)‐clausenamide potentiated synaptic transmission in both anesthetized and freely moving animals while (+)‐clausenamide showed no or little effect; (2) (−)‐clausenamide increased the magnitude of long‐term potentiation (LTP) induced by high‐frequency stimulation (HFS) in anesthetized animals whereas (+)‐clausenamide had no effect; (3) voltage‐dependent calcium channels (VDCCs) calcineurin and calpain are involved in (−)‐clausenamide‐induced potentiation of synaptic transmission. Because hippocampal LTP is thought to reflect a cellular mechanism involved in learning and memory, our findings may provide the pharmacological basis for understanding the nootropic mechanisms of (−)‐clausenamide, which is the first chiral nootropic agent developed in China. Chirality 17:239–244, 2005. © 2005 Wiley‐Liss, Inc.
Anisotropic meshes and streamline‐diffusion stabilization for convection–diffusion problems
Authors: Linß Torsten
Published: April 2005

We study a convection‐diffusion problem with dominant convection. Anisotropic streamline aligned meshes with high aspect ratios are recommended to resolve characteristic interior and boundary layers and to achieve high accuracy. We address the question of how the stabilization parameter in the streamline‐diffusion FEM (SDFEM) and the Galerkin least‐squares FEM (GLSFEM) should be chosen inside the layers. Using a residual free bubbles approach, we show that within the layers the stabilization must be drastically reduced. Copyright © 2005 John Wiley & Sons, Ltd.
An approach to understanding avalanche statistics in mean‐field driven threshold systems
Authors: Preston Eric F. , Sá Martins Jorge S.
Published: April 2005

Driven threshold models that produce complex histories of avalanches are used to simulate the dynamics of many complex interacting systems, such as earthquake generating faults and neural networks. A mean‐field model may be formulated in a way that makes avalanches Abelian, so the final size of the avalanche depends only on the initial conditions, not the algorithm. If the initial stress distribution is statistically stationary, the avalanche size distribution is generated by the first intersection of a random process with a curvilinear boundary. Solutions show that such mean‐field models are never truly critical, but always exhibit dissipation or finite‐size effects. © 2005 Wiley Periodicals, Inc. Complexity 10:68–72, 2005
Quantum calculation of thermal effect in quantum‐dot cellular automata
Authors: Sturzu Ioan , Khatun Mahfuza
Published: April 2005

We present a theoretical study of thermal effect in quantum‐dot cellular automata (QCA). An extended Hubbard‐type model for the Hamiltonian of the QCA arrays, and canonical distribution were used to obtain thermal average of polarization for the QCA cells. A full‐basis quantum method has been used for the calculation of response function for a two‐ and a three‐cell array system. Each cell is composed of four dots located at the corners of the cells. Results show that the nonlinear behavior of the response function functions decay with the temperature as well as with the number of cells in the array. © 2005 Wiley Periodicals, Inc. Complexity 10: 73–78, 2005
Generalization testing with atypical and typical antipsychotic drugs in rats trained to discriminate 5.0 mg/kg clozapine from vehicle in a two‐choice drug discrimination task
Authors: Prus Adam J. , Philibin Scott D. , Pehrson Alan L. , Stephens Chad L. , Cooper Rhiannon N. , Wise Laura E. , Porter Joseph H.
Published: April 2005

Clozapine (CLZ) drug discrimination is used as a preclinical model to evaluate compounds for putative atypical antipsychotic properties. In rats, a 1.25 mg/kg CLZ training dose appears to have greater pharmacological specificity for atypical antipsychotic drugs than the traditional 5.0 mg/kg CLZ training dose; however, methodological differences among studies have precluded a direct comparison between these training doses. In the present study, rats were trained to discriminate a 5.0 mg/kg CLZ dose from vehicle in a two‐choice drug discrimination task using methods similar to those in a previous study from our laboratory that used a 1.25 mg/kg CLZ training dose. Clozapine produced full substitution (≥80% CLZ‐lever responding) for itself at the training dose (5.0 mg/kg). The atypical antipsychotics olanzapine, quetiapine, and ziprasidone also produced full substitution for 5.0 mg/kg CLZ, whereas the atypical antipsychotics risperidone and sertindole produced partial substitution (≥60% CLZ‐lever responding). The typical antipsychotic, thioridazine, produced full substitution for the 5.0 mg/kg CLZ training dose, but the typical antipsychotics chlorpromazine, fluphenazine, and haloperidol failed to substitute for clozapine. In a subgroup of 1.25 mg/kg CLZ‐trained rats, ziprasidone produced strong partial substitution (73.0 % CLZ‐lever responding) for the 1.25 mg/kg CLZ training dose. Based on these findings, some atypical antipsychotic drugs (i.e., quetiapine and ziprasidone) produce full substitution only for the 5.0 mg/kg CLZ training dose, whereas other atypical antipsychotic drugs (i.e., sertindole and risperidone) produce full substitution only for the 1.25 mg/kg CLZ training dose. Thus, both of these training doses are important for the screening of putative atypical antipsychotic drugs with the clozapine drug discrimination assay. Drug Dev. Res. 64:55–65, 2005. © 2005 Wiley‐Liss, Inc.
Antinociceptive and antiinflammatory effects of ketoprofen are potentiated by a vitamin B mixture in the rat
Authors: Rodríguez‐Silverio Juan , Aguilar‐Carrasco José Carlos , Reyes‐García Gerardo , Medina‐Santillán Roberto , Flores‐Murrieta Francisco J.
Published: April 2005

Ketoprofen is a nonsteroidal antiinflammatory drug (NSAID) widely used in therapeutics. However, gastrointestinal toxicity may limit its use. To reduce the requirements of NSAIDs and hence their toxicity, these compounds have been combined with several drugs. B vitamins increase the analgesic activity of NSAIDs, but conflicting results have been obtained. The purpose of this study was to establish whether a vitamin B mixture can increase the antinociceptive effect of ketoprofen in the thermal paw stimulation model and in antiinflammatory activity in carrageenan‐induced paw edema in the rat. Ketoprofen produced a dose‐dependent antinociception, whereas a mixture of B vitamins produced a very limited antinociceptive effect. However, B vitamins were able to increase the antinociceptive effect of ketoprofen, reaching effects similar to those obtained with the maximal dose of ketoprofen tested. Ketoprofen produced a dose‐dependent antiinflammatory activity and B vitamins also produced significant antiinflammatory effects. When ketoprofen was combined with a mixture of B vitamins, an increase in the antiinflammatory action was observed. These results indicate that coadministration of B vitamins with ketoprofen can increase both antihyperalgesic and antiinflammatory effects. Thus, B vitamins are effective as analgesic adjuvants in the models tested. Drug Dev. Res. 64:66–70, 2005. © 2005 Wiley‐Liss, Inc.
Memantine does not influence AChE inhibition in rat brain by donepezil or rivastigmine but does with DFP and metrifonate in in vivo studies
Authors: Gupta Ramesh C. , Dekundy A.
Published: April 2005

This in vivo study investigated whether the N‐methyl‐d‐aspartate receptor antagonist, memantine (MEM), interacts with inhibition of acetylcholinesterase (AChE) by reversible (donepezil and rivastigmine) and irreversible (diisopropyl fluorophosphate (DFP) and metrifonate) AChE inhibitors (AChEIs) in rat brain regions (cortex and hippocampus), which are affected in humans with Alzheimer's disease. MEM (10 mg/kg, e.g., two to four times greater than the therapeutically relevant dose) was administered 15 min prior to donepezil (0.75 or 1.5 mg/kg), rivastigmine (0.35 or 0.7 mg/kg), metrifonate (55 or 110 mg/kg), or DFP (1.5 or 3.0 mg/kg). DFP was used as positive control. Rats were sacrificed at the time of maximal AChE inhibition (determined from time course studies; 15 min after donepezil, 30 min after rivastigmine or metrifonate, 60 min after DFP) to determine AChE activity in the brain region homogenates. Neither MEM nor AChEIs produced any behavioral effects at any time during the study, except metrifonate, which produced muscle tremors and fasciculations at 110 mg/kg. The present studies showed that i) MEM itself did not inhibit AChE in any brain area; ii) MEM did not interact with AChE inhibition induced by therapeutically used AChEIs (donepezil and rivastigmine) at either dose level; iii) MEM prevented AChE inhibition caused by DFP or metrifonate; and (iv) MEM prevented metrifonate‐induced tremors and fasciculations. These findings indicate that MEM does not influence AChE inhibition by donepezil or rivastigmine, and therefore the possibility exists that either of the two antidementic drugs can be used concurrently with MEM. Drug Dev. Res. 64:71–81, 2005. © 2005 Wiley‐Liss, Inc.
Multidrug resistance proteins (MRPs) and implication in drug development
Authors: Tian Quan , Zhang Jing , Chan Eli , Duan Wei , Zhou Shufeng
Published: April 2005

The multidrug resistance protein (MRP)‐related ABCC family (MRP1, MRP2, MRP3, MRP4, MRP5, MRP6, MRP7, MRP8, and MRP9) belongs to the ATP‐binding cassette (ABC) superfamily of transport proteins. They are capable of transporting a structurally diverse array of endo‐ and xenobiotics and their metabolites across cell membranes. These transporters play an important role in the absorption, disposition, and elimination of these compounds in the body. In particular, increased expression of these drug transporters in tumor cells is associated with resistance to a number of important chemotherapeutic agents. This review highlights the biochemical and pharmacological properties of MRP1‐9 and their implications in drug development. A detailed study on the biochemical function and regulation of MRPs is important in drug development, as this may help to avoid drug toxicity, drug resistance, and drug‐drug interactions and to optimize cancer chemotherapy. Drug Dev. Res. 64:1–18, 2005. © 2005 Wiley‐Liss, Inc.
Novel Membrane Potentiometric Thiocyanate Sensor Based on Tribenzyltin(IV) Dithiocarbamate
Authors: Xu Lan , Yuan Ruo , Chai Ya‐Qin , Fu Ying‐Zi
Published: April 2005

A novel PVC membrane ion‐selective electrode based on tribenzyltin(IV) dithiocarbamate [Sn(IV)–TBDTB] as neutral carrier was developed for thiocyanate (SCN−) determination. The electrode exhibits a near‐Nernstian response for SCN− with a slope of 62.8±2.0 mV per decade over a wide concentration range 1.0×10−1–2.0×10−6 mol L−1 and a detection limit of 1.0×10−6 mol L−1 in MES–NaOH buffer, pH 6.0, at 25 °C. The electrode prepared with 1.5 wt.% Sn(IV)–TBDTB, 32.5 wt.% PVC and 66.0 wt.% 2‐nitrophenyloctyl ether (o‐NPOE) shows optimal response characteristics. Anti‐Hofmeister selectivity sequence for a series of anions shown by the electrode was as follows: SCN−>Sal−>I−>ClO$\rm{ {_{4}^{-}}}$>phCOO−>CH3COO−>Br−>Cl−>NO$\rm{ {_{3}^{-}}}$>NO$\rm{ {_{2}^{-}}}$>Citrate>SO42−. The useful pH range for the electrode was found to be 3–7 with a response time 30–40 s. The electrode has been used for direct determination of thiocyanate in wastewater with satisfactory results.
Highly Sensitive Electrogenerated Chemiluminescence Detecting Ranitidine Based On Chemically Modifying Microenvironment of the Chemiluminescence Reaction
Authors: Zheng Xingwang , Qu Yingjuan , Zhang Zhujun , Zhang Chunmei
Published: April 2005

Using a graphite electrode modified with vaseline and NiO, ranitidine showed a strongly ECL enhancing effect for the weak ECL signal of electrooxidation of luminol. Based on this finding, a more sensitive ECL method for ranitidine was firstly proposed. Under the optimum experimental conditions, the ranitidine hydrochloride concentration in the range of 3.0×10−8–9.0×10−6 mol/L was proportional to the enhancing ECL signal and offered a 9×10−9 mol/L detection limit for ranitidine hydrochloride. At the same time, based on the investigation on this ECL reaction mechanism, a new concept, to improve the suitable ECL reaction micro‐environment with chemically modified electrode technique for the better analytical performances of ECL analysis was also firstly proposed.
Simultaneous synthesis of waste interception and material reuse networks: Problem reformulation for global optimization
Authors: Gabriel Frederico B. , El‐Halwagi Mahmoud M.
Published: April 2005

Recycling and reuse of materials are among the most important pollution prevention strategies. In many cases, direct recycling/reuse of process and waste streams may not be feasible because of the intolerable levels of contaminants that can be detrimental to the process performance or can build up to unacceptable levels. Therefore, interception may be used to selectively remove pollutants from the process streams using separation devices or interceptors. In this work, we develop a systematic procedure for the simultaneous synthesis of material reuse and interception networks. A structural representation of the solution alternatives is first presented using a source–interception–sink framework. Then, a generally applicable mathematical formulation is developed. Because of the nonconvexities associated with the general mathematical program, we invoke a number of simplifying assumptions to facilitate reformulation of the problem into a linear program. The concepts of source substreams and interceptor decomposition were used to facilitate the problem reformulation. Additionally, the tasks of assessing interceptor performance and cost were transformed into presynthesis calculations that can be conducted a priori without compromising the accuracy of the models. The problem reformulation yields a linear program that can be solved globally. A case study is solved to illustrate the developed procedure. © 2005 American Institute of Chemical Engineers Environ Prog, 2005
The role of moisture cycling in the weathering of a quartz chlorite schist in a tropical environment: findings of a laboratory simulation
Authors: Wells Tony , Binning Philip , Willgoose Garry
Published: April 2005

Long‐term weathering of a quartz chlorite schist via wetting and drying was studied under a simulated tropical climate. Cubic rock samples (15 mm × 15 mm × 15 mm) were cut from larger rocks and subjected to time‐compressed climatic conditions simulating the tropical wet season climate at the Ranger Uranium Mine in the Northern Territory, Australia. Fragmentation, moisture content and moisture uptake rate were monitored over 5000 cycles of wetting and drying. To determine the impact of climatic variables, five climatic regimes were simulated, varying water application, temperature and drying. One of the climatic regimes reproduced observed temperature and moisture variability at the Ranger Uranium Mine, but over a compressed time scale.

It is shown that wetting and drying is capable of weathering quartz chlorite schist with changes expected over a real time period of decades. While wetting and drying alone does produce changes to rock morphology, the incorporation of temperature variation further enhances weathering rates. Although little fragmentation occurred in experiments, significant changes to internal pore structure were observed, which could potentially enhance other weathering mechanisms. Moisture variability is shown to lead to higher weathering rates than are observed when samples are subjected only to leaching. Finally, experiments were conducted on two rock samples from the same source having only subtle differences in mineralogy. The samples exhibited quite different weathering rates leading to the conclusion that our knowledge of the role of rock type and composition in weathering is insufficient for the accurate determination of weathering rates. Copyright © 2005 John Wiley & Sons, Ltd.
Blended and Cross‐Linked Ionomer Membranes for Application in Membrane Fuel Cells
Authors: Kerres J. A.
Published: April 2005

Differently cross‐linked blend membranes were prepared from commercial arylene main‐chain polymers of the poly(etherketone) and poly(ethersulfone) classes, modified with sulfonate groups, sulfinate cross‐linking groups, and basic N‐groups.

The following membrane types have been prepared: (i) Van‐der Waals/dipole‐dipole blends by mixing a polysulfonate with unmodified PSU. This membrane type showed a heterogeneous morphology, leading to extreme swelling and even dissolution of the sulfonated component at elevated temperatures. (ii) Hydrogen bridge blends by mixing a polysulfonate with a polyamide or a polyetherimide. This membrane type showed a partially heterogeneous morphology, also leading to extreme swelling/dissolution of the sulfonated blend component at elevated temperatures. (iii) Acid‐base blends by mixing a polysulfonate with a polymeric N‐base (in‐house developed/commercial). A wide range of properties could be achieved with this membrane type by variation of the different parameters. Membranes showing excellent stability and good fuel cell performance up to 100 °C (PEFC) and 130 °C (DMFC) were obtained. (iv) Covalently cross‐linked (blend) membranes by either mixing a polysulfonate with a polysulfinate or by preparing a polysulfinatesulfonate, followed by reaction of the sulfinate groups in solution with a dihalogeno compound under S‐alkylation. The membranes prepared showed effective suppression of swelling without a loss in the H+‐conductivity. The membranes showed good PEFC (up to 100 °C) and DMFC (up to 130 °C) performance. (v) Covalent‐ionically cross‐linked blend membranes by mixing polysulfonates with polysulfinates and polybases or by mixing a polysulfonate with a polymer carrying both sulfinate and basic N‐groups. The covalent‐ionically cross‐linked membranes were tested in a DMFC up to 110 °C and demonstrated good performance. (vi) Differently cross‐linked organic‐inorganic blend composite membranes via various procedures. The best results were obtained with blend membranes having a layered zirconium phosphate “ZrP” phase: they were transparent, and showed good H+‐conductivity and stability. The application of one of these composite membranes in a PEFC yielded good performance up to T = 115 °C.
Neutron and X‐ray Scattering: Suitable Tools for Studying Ionomer Membranes
Authors: Gebel G. , Diat O.
Published: April 2005

Neutrons and x‐rays were extensively used to study the microstructure of the polymeric membranes for fuel cells. The small‐angle x‐ray and neutron scattering (SAXS and SANS resp.) data for Nafion® and alternative membranes present specific features. The different analyses and proposed models to interpret these data are reviewed. A special emphasis is devoted to the recent elongated polymer particle model which appears as the most efficient model for Nafion® to interpret not only the numerous scattering data but also the transport swelling and mechanical properties. Neutrons can also be used to study the water management in situ in an operating fuel cell either to visualise the water accumulation in the gas distributors or to determine the water concentration profiles through the membrane and during operation.
AGR2, an androgen‐inducible secretory protein overexpressed in prostate cancer
Authors: Zhang Jin‐San , Gong Aiyu , Cheville John C. , Smith David I. , Young Charles Y. F.
Published: April 2005

AGR2, the human homologue of Xenopus anterior gradient 2 (XAG2), was identified by a suppression subtractive hybridization‐based technique as an androgen‐inducible gene. There are two AGR2 transcripts, which encode the same secretory protein of 175 amino acids. The androgen induction was time‐ and dose‐dependent, with more than a 10‐fold increase in the level of AGR2 mRNA after 48 hr of treatment with 10−9 M R1881. Expression of AGR2 mRNA was specifically detected in limited human tissue rich in epithelial cells, including the prostate gland. Analysis of 46 microdissected primary prostate adenocarcinoma samples showed that AGR2 mRNA expression was markedly elevated in the majority of tumors as compared to matched adjacent benign tissues. Androgen‐induced AGR2 protein expression was demonstrated in LNCaP cells by Western blot analysis with an anti‐AGR2 antibody. Immunohistochemistry analysis indicated that AGR2 protein expression was highly restricted to the secretory epithelial cells in the prostate gland. In tissue sections from radical prostatectomy specimens, immunohistochemical staining of AGR2 showed markedly increased expression in high‐grade prostatic intraepithelial neoplasia and Gleason pattern 3−4 prostatic adenocarcinoma. Therefore, the androgen‐induced secretory protein AGR2 may serve as a potential therapeutic target and/or molecular marker for prostate cancer. © 2005 Wiley‐Liss, Inc.
Second‐Generation Inhibitors for the Metalloprotease Neprilysin Based on Bicyclic Heteroaromatic Scaffolds: Synthesis, Biological Activity, and X‐Ray Crystal‐Structure Analysis
Authors: Sahli Stefan , Frank Brian , Schweizer W. Bernd , Diederich François , Blum‐Kaelin Denise , Aebi Johannes D. , Böhm Hans‐Joachim , Oefner Christian , Dale Glenn E.
Published: April 2005

A new class of nonpeptidic inhibitors of the ZnII‐dependent metalloprotease neprilysin with IC50 values in the nanomolar activity range (0.034–0.30 μM) were developed based on structure‐based de novo design (Figs. 1 and 2). The inhibitors feature benzimidazole and imidazo[4,5‐c]pyridine moieties as central scaffolds to undergo H‐bonding to Asn542 and Arg717 and to engage in favorable π‐π stacking interactions with the imidazole ring of His711. The platform is decorated with a thiol vector to coordinate to the ZnII ion and an aryl residue to occupy the hydrophobic S1′ pocket, but lack a substituent for binding in the S2′ pocket, which remains closed by the side chains of Phe106 and Arg110 when not occupied. The enantioselective syntheses of the active compounds (+)‐1, (+)‐2, (+)‐25, and (+)‐26 were accomplished using Evans auxiliaries (Schemes 2, 4, and 5). The inhibitors (+)‐2 and (+)‐26 with an imidazo[4,5‐c]pyridine core are ca. 8 times more active than those with a benzimidazole core ((+)‐1 and (+)‐25) (Table 1). The predicted binding mode was established by X‐ray analysis of the complex of neprilysin with (+)‐2 at 2.25‐Å resolution (Fig. 4 and Table 2). The ligand coordinates with its sulfanyl residue to the ZnII ion, and the benzyl residue occupies the S1′ pocket. The 1H‐imidazole moiety of the central scaffold forms the required H‐bonds to the side chains of Asn542 and Arg717. The heterobicyclic platform additionally undergoes π‐π stacking with the side chain of His711 as well as edge‐to‐face‐type interactions with the side chain of Trp693. According to the X‐ray analysis, the substantial advantage in biological activity of the imidazo‐pyridine inhibitors over the benzimidazole ligands arises from favorable interactions of the pyridine N‐atom in the former with the side chain of Arg102. Unexpectedly, replacement of the phenyl group pointing into the deep S1′ pocket by a biphenyl group does not enhance the binding affinity for this class of inhibitors.
Replacement of Canonical DNA Nucleobases by Benzotriazole and 1,2,3‐Triazolo[4,5‐d]pyrimidine: Synthesis, Fluorescence, and Ambiguous Base Pairing
Authors: Seela Frank , Jawalekar Anup M. , Münster Ingo
Published: April 2005

The syntheses and the fluorescence properties of 7H‐3,6‐dihydro‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐one 2′‐deoxy‐β‐D‐ribonucleosides (=2′‐deoxy‐8‐azainosine) 3 (N3), 15 (N2), and 16 (N1) as well as of 1,2,3‐benzotriazole 2′‐O‐methyl‐β‐ or ‐α‐D‐ribofuranosides 6 (N1) and 24 (N1) are described. Also the fluorescence properties of 1,2,3‐benzotriazole 2′‐deoxy‐β‐D‐ribofuranosides 4 (N1) and 5 (N2) are evaluated. From the nucleosides 3–6, the phosphoramidites 19, 26a, 26b, and 28 are prepared and employed in solid‐phase oligonucleotide synthesis. In 12‐mer DNA duplexes, compound 3 shows similar ambiguous base‐pairing properties as 2′‐deoxyinosine (1), while the nucleosides 4–6 show strong pairing with each other and discriminate very little the four canonical DNA constituents.
A Microwave‐Accelerated Esterification of α,β‐Unsaturated Acids with Alkyl or Aryl Carbonochloridate and Triethylamine in Acetonitrile as a Novel Esterifying Reagent Mixture
Authors: Pathania Vinod , Sharma Anuj , Sinha Arun K.
Published: April 2005

An efficient synthesis of α,β‐unsaturated esters by treatment of the corresponding acids with alkyl or aryl carbonochloridate, triethylamine, and acetonitrile was accomplished for the first time under microwave irradiation for 10 min. The esters 1b–24b were isolated in 71–97% yield.
A Novel Asymmetric ent‐Kaurane Dimer from Isodon rubescens var. rubescens
Authors: Han Quan‐Bin , He Zhen‐Dan , Qiao Chun‐Feng , Xu Hong‐Xi , Sun Han‐Dong
Published: April 2005

A novel asymmetric ent‐kaurane dimer, xindongnin P (1), was isolated from Isodon rubescens var. rubescens. Its structure was elucidated by detailed spectroscopic analysis. Compound 1 contains a tetrahydrofuran moiety whose formation leads to inversion of configuration at C(16). This differentiates 1 from known related dimers, which were isolated before from the Isodon genus. A likely biogenetic pathway from the alleged monomer precursor 3 is proposed.
Longistylumphyllines A–C, Three New Alkaloids from Daphniphyllum longistylum
Authors: Chen Xin , Zhan Zha‐Jun , Yue Jian‐Min
Published: April 2005

Three new alkaloids, longistylumphyllines A–C (1–3), together with the six known alkaloids deoxycalyciphylline B, deoxyisocalyciphylline B, methyl homosecodaphniphyllate, daphnicyclidin A, daphnicyclidin B, and daphnicyclidin F, were isolated from the stems and leaves of Daphniphyllum longistylum. Their structures and relative configuration were elucidated on the basis of spectroscopic data, especially 1D and 2D NMR techniques.
Formation of 6,10‐Diphenyl‐Substituted Heptalene‐4,5‐dicarboxylates
Authors: Jin Xudong , Linden Anthony , Hansen Hans‐Jürgen
Published: April 2005

It is shown that 4,8‐diphenylazulene (1) can be easily prepared from azulene by two consecutive phenylation reactions with PhLi, followed by dehydrogenation with chloranil. Similarly, a Me group can subsequently be introduced with MeLi at C(6) of 1 (Scheme 2). This methylation led not only to the expected main product, azulene 2, but also to small amounts of product 3, the structure of which has been determined by X‐ray crystal‐structure analysis (cf. Fig. 1). As expected, the latter product reacts with chloranil at 40° in Et2O to give 2 in quantitative yields. Vilsmeier formylation of 1 and 2 led to the formation of the corresponding azulene‐1‐carbaldehydes 4 and 5. Reduction of 4 and 5 with NaBH4/BF3 ⋅ OEt2 in diglyme/Et2O 1 : 1 and BF3 ⋅ OEt2, gave the 1‐methylazulenes 6 and 7, respectively. In the same way was azulene 9 available from 6 via Vilsmeier formylation, followed by reduction of azulene‐1‐carbaldehyde 8 (Scheme 3). The thermal reactions of azulenes 1, 6, and 7 with excess dimethyl acetylenedicarboxylate (ADM) in MeCN at 100° during 72 h afforded the corresponding heptalene‐4,5‐dicarboxylates 11, 12, and 13, respectively (Scheme 4). On the other hand, the highly substituted azulene 9 gave hardly any heptalene‐4,5‐dicarboxylate.
Patterns in stream longitudinal profiles and implications for hyporheic exchange flow at the H.J. Andrews Experimental Forest, Oregon, USA
Authors: Anderson Justin K. , Wondzell Steven M. , Gooseff Michael N. , Haggerty Roy
Published: April 2005

There is a need to identify measurable characteristics of stream channel morphology that vary predictably throughout stream networks and that influence patterns of hyporheic exchange flow in mountain streams. In this paper we characterize stream longitudinal profiles according to channel unit spacing and the concavity of the water surface profile. We demonstrate that: (1) the spacing between zones of upwelling and downwelling in the beds of mountain streams is closely related to channel unit spacing; (2) the magnitude of the vertical hydraulic gradients (VHGs) driving hyporheic exchange flow increase with increasing water surface concavity, measured at specific points along the longitudinal profile; (3) channel unit spacing and water surface concavity are useful metrics for predicting how patterns in hyporheic exchange vary amongst headwater and mid‐order streams. We use regression models to describe changes in channel unit spacing and concavity in longitudinal profiles for 12 randomly selected stream reaches spanning 62 km2 in the H.J. Andrews Experimental Forest in Oregon. Channel unit spacing increased significantly, whereas average water surface concavity (AWSC) decreased significantly with increasing basin area. Piezometer transects installed longitudinally in a subset of stream reaches were used to measure VHG in the hyporheic zone, and to determine the location of upwelling and downwelling zones. Predictions for median pool length and median distance between steps in piezometer reaches bracketed the median distance separating zones of upwelling in the stream bed. VHG in individual piezometers increased with increasing water surface concavity at individual points in the longitudinal profile along piezometer transects. Absolute values of VHG, averaged throughout piezometer transects, increased with increasing AWSC, indicating increased potential for hyporheic exchange flow. These findings suggest that average hyporheic flow path lengths increase—and the potential for hyporheic exchange flow in stream reaches decreases—along the continuum from headwater to mid‐order mountain streams. Copyright © 2005 John Wiley & Sons, Ltd.
Direct correlation between adsorption‐induced changes in protein structure and platelet adhesion
Authors: Hylton Donna M. , Shalaby Shalaby W. , Latour Robert A.
Published: April 2005

It is widely recognized that adsorbed proteins on biomaterial surfaces tend to initiate thrombus formation, although the specific mechanisms involved are still not well understood. In attempts to decrease the conformational change of adsorbed proteins, surface treatments that reduce surface hydrophobicity have been considered, such as the sulfonation of low‐density polyethylene and isotactic polypropylene. The objectives of this present research were to study how changes in surface chemistry influence the degree of conformational change of adsorbing proteins and to investigate the correlation between the change in adsorbed protein structure and platelet response. Adsorbed porcine serum albumin and porcine fibrinogen were used as the model proteins for determining the effects of sulfonation on protein conformational change. Circular dichroism spectroscopy studies showed that the proteins were less altered structurally on the sulfonated surfaces. Platelet adhesion studies were used to correlate the number of adhered platelets with the amount of conformational change in adsorbed proteins on the polymer surface. The results of these studies show a linear correlation between platelet adhesion and the degree of adsorption‐induced protein conformational change. These findings suggest that the degree of protein conformational change after adsorption is a dominant mechanism governing platelet interactions with biomaterial surfaces. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 349–358, 2005
The viability and function of primary rat hepatocytes cultured on polymeric membranes developed for hybrid artificial liver devices
Authors: Grant M. Helen , Morgan Caroline , Henderson Catherine , Malsch Günther , Seifert Barbara , Albrecht Wolfgang , Groth Thomas
Published: April 2005

Bioartificial liver devices require membranes to support the function and viability of hepatocytes because they are anchorage‐dependent cells. This study investigated the ability of several polymeric membranes to support the functions of primary hepatocyte cultures. Tailor‐made membranes were sought by synthesizing acrylonitrile copolymers with different comonomers resulting in ionic, hydrophilic, or reactive functional groups on the polymer surface. Hepatocyte morphology and viability were assessed by confocal microscopy, and function by the content and activities of cytochrome P450, and the expression of glutathione S‐transferases. Hydrophilic membranes (polyacrylonitrile and acrylonitrile copolymerized with 2‐acrylamino‐2‐methyl‐propane sulfonic acid) were more biocompatible than hydrophobic membranes such as polysulfone. The chemistry of the hydrophilic group was important; amine groups had a deleterious effect on maintenance of the primary hepatocytes. The biocompatibility of hydrophobic membranes was improved by collagen coating. Improving the chemistry of membranes for artificial liver devices will enhance the phenotypic stability of the cells, enabling us to prolong treatment times for patients. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 367–375, 2005
Importance of accurate charges in molecular docking: Quantum mechanical/molecular mechanical (QM/MM) approach
Authors: Cho Art E. , Guallar Victor , Berne Bruce J. , Friesner Richard
Published: April 2005

The extent to which accuracy of electric charges plays a role in protein‐ligand docking is investigated through development of a docking algorithm, which incorporates quantum mechanical/molecular mechanical (QM/MM) calculations. In this algorithm, fixed charges of ligands obtained from force field parameterization are replaced by QM/MM calculations in the protein environment, treating only the ligands as the quantum region. The algorithm is tested on a set of 40 cocrystallized structures taken from the Protein Data Bank (PDB) and provides strong evidence that use of nonfixed charges is important. An algorithm, dubbed “Survival of the Fittest” (SOF) algorithm, is implemented to incorporate QM/MM charge calculations without any prior knowledge of native structures of the complexes. Using an iterative protocol, this algorithm is able in many cases to converge to a nativelike structure in systems where redocking of the ligand using a standard fixed charge force field exhibits nontrivial errors. The results demonstrate that polarization effects can play a significant role in determining the structures of protein‐ligand complexes, and provide a promising start towards the development of more accurate docking methods for lead optimization applications. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 915–931, 2005
Measuring human cardiac tissue sodium concentrations using surface coils, adiabatic excitation, and twisted projection imaging with minimal T2 losses
Authors: Ouwerkerk Ronald , Weiss Robert G. , Bottomley Paul A.
Published: April 2005

Purpose

To measure tissue sodium concentrations in the human heart with 23Na MRI using a surface coil, thereby eliminating the effects of inhomogeneous excitation by surface coils and minimizing T1 and T2 relaxation.

Materials and Methods

We combined fully relaxed, very short‐echo, 23Na twisted projection imaging (TPI) with adiabatic half passage (AHP) excitation and external referencing on subjects and comparing with a concentration reference phantom scan to quantify TSC with surface coils. 23Na signal losses during hard (square), composite, and tanh/tan amplitude/frequency‐modulated AHP excitation pulses were analyzed over a wide range of RF field strengths and T2short values.

Results

AHP excitation yielded a homogeneous excitation flip angle and negligible losses compared to a 90° hard pulse wherever the B1 field exceeded the adiabatic threshold, rendering this sequence suitable for applications that use surface coil excitation. An AHP 23Na TPI sequence was used with a surface coil at 1.5 T to noninvasively quantify myocardial TSC in 10 normal volunteers. The mean TSC was 43 ± 4, 53 ± 12, and 17 ± 4 μmol/g in the left ventricular (LV) free wall, septum, and adipose tissue, respectively, consistent with prior invasive measurements on biopsy and autopsy specimens.

Conclusion

It is now possible to noninvasively quantify TSC in the human heart with surface coil 23Na MRI. J. Magn. Reson. Imaging 2005;21:546–555. © 2005 Wiley‐Liss, Inc.
Effect of inversion time on delayed‐enhancement magnetic resonance imaging with and without phase‐sensitive reconstruction
Authors: Setser Randolph M. , Chung Yiu Cho , Weaver Joan A. , Stillman Arthur E. , Simonetti Orlando P. , White Richard D.
Published: April 2005

Purpose

To evaluate the consistency and inversion time (TI) independence of phase‐sensitive reconstruction (PSIR) delayed‐enhancement (DE) MRI in a clinical setting.

Materials and Methods

Mid‐ventricular short‐axis DE images were acquired in 25 patients using three TIs: 1) optimized to null viable myocardium, 2) 50 msec less than optimal TI, and 3) 50 msec greater than optimal TI. At each TI, images were acquired with PSIR and without magIR. In each image, percent scar was computed as the ratio of nonviable to total pixels in the left ventricle (LV).

Results

In the magIR images, percent scar was 23% ± 15% (optimal), 11% ± 11% (short), and 22% ± 15% (long). In PSIR images, percent scar was 25% ± 15% (optimal), 22% ± 15% (short), and 22% ± 14% (long). Percent scar was significantly underestimated in magIR images with short TI, but no statistically significant difference in percent scar was observed at the optimal or long TIs.

Conclusion

DE‐MRI is a robust imaging technique for clinical use. PSIR provided consistent image quality independently of TI, at least over the range of TIs evaluated in this study. However, neither image quality nor scar appearance in the PSIR images was significantly different from that in the magIR images when TI was at or above the null point of viable myocardium. J. Magn. Reson. Imaging 2005;21:650–655. © 2005 Wiley‐Liss, Inc.
Recombinant protein‐based ELISA and immuno‐cytochemical assay for the diagnosis of SARS
Authors: Carattoli Alessandra , Bonito Paola Di , Grasso Felicia , Giorgi Colomba , Blasi Francesco , Niedrig Matthias , Cassone Antonio
Published: April 2005

A new Coronavirus (SARS‐CoV) is the aetiological agent of the severe acute respiratory syndrome (SARS). Because of the critical role played by serological assays for SARS diagnosis, an in‐house ELISA based on SARS‐CoV recombinant antigens was developed. The SARS‐CoV nucleocapsid protein (N), three N fragments (N1, N2, and N3) and the intraviral domain of the membrane protein (M2) were cloned and expressed in Escherichia coli as histidine‐tagged proteins. Six reference sera from SARS patients were used to detect virus‐specific IgG in an ELISA using each recombinant protein as coating antigen. High‐titre positive reactions were detected in all SARS positive sera. The specificity of the assay appears to be high as no positive reaction was detected in the sera of 20 healthy subjects and 73 patients with non‐SARS, low‐tract respiratory infections. Specific hyper‐immune sera to SARS‐CoV and the recombinant proteins, N, N1, N2, N3, and M2 were also generated in mice and rabbits. The specificity of these sera was confirmed by an immunocytochemical assay on biochips of SARS‐CoV infected and uninfected cells. J. Med. Virol. 76:137–142, 2005. © 2005 Wiley‐Liss, Inc.
Oligonucleotide array for simultaneous detection of respiratory viruses using a reverse‐line blot hybridization assay
Authors: Coiras M.T. , López‐Huertas M.R. , López‐Campos G. , Aguilar J.C. , Pérez‐Breña P.
Published: April 2005

The interest in developing new diagnostic methods based on arrays of multiple probes to detect and type simultaneously a wide range of different infectious agents is increasing. This becomes a necessity in the case of infectious agents such as respiratory viruses that cause diseases with very similar signs and symptoms. Such tools will permit rapid and accurate diagnosis of different agents causing respiratory infection leading to the most adequate prevention and/or treatment measures. In this article a reverse‐line blot hybridization (RLB) assay for the detection of a wide range of respiratory viruses is presented and evaluated for its usefulness in routine diagnosis. This assay employs an array of 18 oligonucleotide probes immobilized on a nylon membrane. Biotin‐labeled PCR products obtained with two multiplex reverse transcription (RT)‐polymerase chain reaction (PCR) assays described previously, which allow for the detection of fourteen different groups of respiratory viruses, were hybridized to the oligonucleotide array. Detection was performed using a chemiluminescent method. The standardization of the method showed that the RLB assay could be an alternative to the nested PCR assay for enhancing the sensitivity in the detection of the amplified products, avoiding the problem of cross‐over contamination, increasing the specificity, and therefore simplifying the method. This is of main interest in laboratories with few facilities. The feasibility and accuracy of the RT‐PCR‐RLB assay for detecting respiratory viruses proves that such approach could be a first stage to develop a microarray assay for routine diagnosis of infectious diseases. J. Med. Virol. 76:256–264, 2005. © 2005 Wiley‐Liss, Inc.
Non‐planar heme deformations and excited state displacements in horseradish peroxidase detected by Raman spectroscopy at Soret excitation
Authors: Huang Qing , Schweitzer‐Stenner Reinhard
Published: April 2005

We studied the out‐of‐plane modes of horseradish peroxidase (HRP) in different spin, oxidation and ligation states by measuring the respective resonance Raman spectra with (near) Soret excitation. The non‐planar modes of the heme are Raman inactive for planar macrocycles, but become resonance Raman active in the presence of out‐of‐plane deformations. The thus induced Raman scattering results mostly from Franck–Condon type coupling. We observed bands from a variety of out‐of‐plane modes such as γ5, γ6, γ7(A2u) modes, γ21 and γ22(Eg), γ15(B2u) and γ11(B1u). The appearance of these bands is clearly indicative of non‐planar deformations of the same symmetry. We determined the relative intensities of all sufficiently intense Raman modes of ferric pentacoordinated, quantum mixed and hexacoordinated low‐spin as well as of ferrous pentacoordinated high‐spin HRP C. The apparent vibronic coupling parameters were obtained from a self‐consistent analysis of the Raman intensities and the respective optical absorption spectrum. They revealed significantly reduced displacements of the excited B‐state for the ferrous, deoxy‐like state compared with the resting ferric state. An analysis of the obtained coupling strengths of out‐of‐plane modes revealed that they are predominantly induced by static non‐planar deformations along the normal coordinates of the lowest wavenumber modes of a given symmetry type. We used the deformations of the heme in resting HRP C to determine the vibronic coupling strength of the experimentally detectable out‐of‐plane modes and subsequently employed this information to obtain the non‐planar deformations for the investigated ferric hexacoordinated low‐spin state. This yielded a substantial reduction of the ruffling distortion, whereas the doming deformation remained mostly unaffected by the change of the iron's spin and ligation state. Copyright © 2005 John Wiley & Sons, Ltd.
Theoretical study of the heating of solid ellipsoidal nanoparticle
in media by short laser pulses
Authors: Pustovalov V K
Published: April 2005

Theoretical investigation is carried out of the heating
of a small solid (metal) ellipsoidal particle in a liquid or
gaseous medium by laser radiation pulses. The solutions are
obtained for quasi-stationary distributions of temperature inside
and around of a particle and conductive heat transfer between the
particle and the surrounding medium with allowance for the
temperature dependence of the transfer coefficients. The heating
of ellipsoidal nanoparticle in medium on exposure to laser
radiation pulse and following cooling is considered on the base of
analytical solutions. The time dependencies of particle
temperature are obtained. The estimation of absorbed and scattered
laser radiation energies by gold ellipsoidal nanoparticles, their
maximal temperatures and comparison with experimental data is
made.