bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThis 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

AbstractThe 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

AbstractA 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

AbstractUsing 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

AbstractRecycling 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

AbstractLong‐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

AbstractDifferently 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

AbstractNeutrons 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

AbstractAGR2, 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

AbstractA 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

AbstractThe 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

AbstractAn 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

AbstractA 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

AbstractThree 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

AbstractIt 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

AbstractThere 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.