bluuebunny/crossref_metadata_2025 huggingface dataset:
Capillary electrophoresis of proteins in dextran‐coated columns
Authors: Zhang Jian , Horváth Csaba
Published: March 2003

A simple coating technique by using uncross‐linked dextran has been developed for fused‐silica capillaries to be used in capillary electrophoresis of basic proteins. The capillaries were first silanized with a heterobifunctional silane (γ‐aminopropyltriethoxylsilane), which served as a coupling agent between the capillary inner wall and the polysaccharide coating. Dextran of high molecular mass (about 70 kDa) was activated with 1,1'‐carbonyldiimidazole. Then the activated dextran was coupled to the primary amino groups that were anchored onto the inner wall of the silanized capillaries. The residual reactive groups on the dextran were further substituted by neutral functions in a coupling reaction with excess ethanolamine. By using dimethyl sulfoxide (DMSO) rather than aqueous buffer as the reaction medium, the extent of substitution was improved by minimizing the residual reactive groups at the surface. Since they are ionogenic, the electrosmotic flow in the system is relatively low. The chemically bound dextran coating showed good reproducibility and stability. In electrophoretic experiments basic proteins were separated with high efficiency by use of the dextran‐coated fused‐silica capillary columns. The main advantage of the method described here is that both polysaccharide activation and amine‐coupling reactions were carried out under mild conditions at room temperature without catalysts. For this reason, the method is recommended to coat the inner wall of microfluidic separation channels which would not tolerate a harsh treatment.
A versatile microfabricated platform for electrophoresis of double‐ and single‐stranded DNA
Authors: Ugaz Victor M. , Lin Rongsheng , Srivastava Nimisha , Burke David T. , Burns Mark A.
Published: March 2003

We demonstrate a versatile microfabricated electrophoresis platform, incorporating arrays of integrated on‐chip electrodes, heaters, and temperature sensors. This design allows a range of different sieving gels to be used within the same device to perform separations involving both single‐ and double‐stranded DNA over distances on the order of 1 cm. We use this device to compare linear and cross‐linked polyacrylamide, agarose, and thermo‐reversible Pluronic‐F127 gels on the basis of gel casting ease, reusability, and overall separation performance using a 100 base pair double‐stranded DNA ladder as a standard sample. While cross‐linked polyacrylamide matrices provide consistently high‐quality separations in our system over a wide range of DNA fragment sizes, Pluronic gels also offer compelling advantages in terms of the ability to remove and reload the gel. Agarose gels offer good separation performance, however, additional care must be exercised to ensure consistent gel properties as a consequence of the need for elevated gel loading temperatures. We also demonstrate the use of denaturing cross‐linked polyacrylamide gels at concentrations up to 19% to separate single‐stranded DNA fragments ranging in size from 18 to 400 bases in length. Primers differing by 4 bases at a read length of 30 bases can be separated with a resolution of 0.9–1.0 in under 20 min. This level of performance is sufficient to conduct a variety of genotyping assays including the rapid detection of single nucleotide polymorphisms (SNPs) in a microfabricated platform. The ability to use a single microelectrophoresis system to satisfy a wide range of separation applications offers molecular biologists an unprecedented level of flexibility in a portable and inexpensive format.
Low‐voltage electroosmosis pump for stand‐alone microfluidics devices
Authors: Takamura Yuzuru , Onoda Hiroyuki , Inokuchi Hiromichi , Adachi Sakuichiro , Oki Akio , Horiike Yasuhiro
Published: March 2003

Two types of low‐voltage electroosmosis pumps were developed using microfabrication technology for usage in handy or stand‐alone applications of the micrototal analysis systems (μ‐TAS) and the lab‐on‐a‐chip. This was done by making a thin (< 1 μm) region in the flow path and by only applying voltages near this thin region using electrodes inserted into the flow path. The inserted electrodes must be free from bubble formation and be gas‐tight in order to avoid pressure leakage. For these electrodes, Ag/AgCl or a gel salt bridge was used. For patterning the gel on the chip, a hydrophilic photopolymerization gel and a photolithographic technique were optimized for producing a gel with higher electric conductivity and higher mechanical strength. For high flow rate application, wide (33.2 mm) and thin (400 nm) pumping channels were compacted into a 1 mm×6 mm area by folding. This pump achieves an 800 Pa static pressure and a flow of 415 nL/min at 10 V. For high‐pressure application, a pump was designed with the thin and thick regions in series and positive and negative electrodes were inserted between them alternatively. This pump could increase the pumping pressure without increasing the supply voltage. A pump with 10‐stage connections generated a pressure of 25 kPa at 10 V.
Integration of on‐column immobilized enzyme reactor in microchip electrophoresis
Authors: Park Sung‐Soo , Cho Seung Il , Kim Min‐Su , Kim Yong‐Kweon , Kim Byung‐Gee
Published: March 2003

A simple method integrating an immobilized enzyme reactor into a microchip electrophoresis device was developed. The enzyme immobilization into a microchip was performed by spotting and drying a drop of dissolved nitrocellulose (NC) on a glass substrate, and adsorbing enzyme on the reconstituted NC membrane. This enzyme‐immobilized glass plate was assembled with a polydimethylsiloxane substrate on which the separation channel was fabricated. The advantage of this method is the ability to easily change the position and size of the reactor within the microchip electrophoresis device. A β‐galactosidase reaction was demonstrated with fluorescein di‐β‐D‐galactopyranoside using this integrated on‐column enzyme reactor. A successful electrophoretic separation of its hydrolysis products, i.e., fluorescein mono‐β‐D‐galactopyranoside (FMG) and fluorescein, was achieved. Enzyme kinetics and inhibition of the β‐galactosidase using FMG and 2‐phenylethyl β‐D‐thiogalactoside, respectively, were also studied with microchip electrophoresis.
Identification of nuclear proteins of small cell lung cancer cell line H82: An improved procedure for the analysis of silver‐stained proteins
Authors: González Luis Javier , Castellanos‐Serra Lila , Badock Volker , Díaz Maylín , Moro Alejandro , Perea Silvio , Santos Alicia , Paz‐Lago Dalila , Otto Albrecht , Müller Eva‐Christina , Kostka Susanne , Wittmann‐Liebold Brigitte , Padrón Gabriel
Published: March 2003

An efficient method for digestion and extraction of proteolytic peptides from silver‐stained proteins was applied to the characterization of nuclear proteins from the small cell lung cancer H82 (ATCC HTB 175) cell line previously separated by high‐resolution large format two‐dimensional gel electrophoresis. From 68 spots, evenly distributed on the gel area and representing a wide range of spot intensities, 63 (92%) were successfully identified by matrix‐assisted laser desorption/ionization (MALDI) or electrospray ionozation‐mass spectrometry (ESI‐MS). In five cases where the identification was not possible, the presence of an intense background apparently due to the leakage of polymers from the microtubes or other plastics, was detected. Extensive analysis of peptide sequences by ESI MS/MS experiments allowed the identification of post‐translational modifications, such as acetylation, phosphorylation, deamidation of asparagine residues and the presence of isoaspartic acid. A new protein variant not reported in sequence databases was also detected.
Activation of platelet‐derived growth factor pathway in human asthmatic pulmonary‐derived mesenchymal cells
Authors: Malmström Johan , Tufvesson Ellen , Löfdahl Claes‐Göran , Hansson Lennart , Marko‐Varga György , Westergren‐Thorsson Gunilla
Published: March 2003

Cell cultures of mesenchymal type were obtained from biopsies taken after bronchoscopy from patients with asthma. It was possible to achieve outgrowth of fibroblast‐like cells from these lung biopsies, which stained for α‐smooth actin indicating that they were of myofibroblast type. Morphologically, two types of myofibroblasts could be observed: one intermediate form with more stretched cell shape and lamellipodia protrusions, and one more differentiated compact form of myofibroblast. The intermediate form was the most dominant type in these patients, indicating an active ongoing remodelling process. Further studies showed that platelet‐derived growth factor (PDGF) might be the factor that stimulates the formation of the intermediate type of myofibroblasts, since it enhance migration of normal human lung fibroblasts 4‐fold compared to control through an induced formation of stress fibers and lamellipodia protrusions. Additionally, intracellular signalling pathways involved in migration, such as RhoA and MAPkinase were stimulated 1.5‐fold and 3.5‐fold, respectively. By using two‐dimensional (2‐D) gel electrophoresis and protein identification by peptide mass finger printing matrix assisted laser desporption/ionization – time of flight – massspectrometry (MALDI‐TOF‐MS) it was possible to confirm that PDGF affected the synthesis of proteins involved in the remodelling process, such as collagen VI and post‐translational forms thereof. PDGF also stimulated the production of FK506 binding protein of 65 kDa, a protein involved in smooth muscle differentiaition, and proteins involved in the rearrangement of the cytoskeleton connected to migration such as the actin related protein ARP3, the T‐complex protein and the heat shock protein 60. We demonstrate that PDGF has a potential pathological role in asthma and formation of subepithelial fibrosis by inducing changes in the proteome.
DNA fragment analysis by an affordable multiple‐channel capillary electrophoresis system
Authors: Liu Ming S. , Amirkhanian Varouj D.
Published: March 2003

We are demonstrating a cost‐effective multichannel capillary electrophoresis system for a high‐efficiency double‐stranded DNA (dsDNA) fragments analysis. This bench‐type high‐performance DNA analysis (HDA™) system uses fluorescence‐type detection with inexpensive solid‐state light sources and nonmoving integrated emission collection micro‐optics. DNA samples are analyzed simultaneously by using a multiple usage and disposable multicapillary cartridge, which contains integrated capillary channels, optical fibers and an integrated sieving gel reservoir. Using commercially available dsDNA size markers as indicators, the HDA™ system provides high resolving power in 7 min separations. The system can hold a total of 192 samples in two 96‐well polymerase chain reaction (PCR) plates, which can be automatically analyzed within 2.5 h. This affordable system can be used in laboratories to replace slab gel electrophoresis for routine and high‐throughput dsDNA analysis.
A comparison between electrokinetic capillary chromatography and absorption spectroscopy for the analysis of peptide‐micelle association by weak hydrophobic interactions
Authors: Hémond Carl , Fürtös‐Matei Alexandra , Waldron Karen C.
Published: March 2003

Micellar electrokinetic capillary chromatography (MEKC) was compared to absorption spectroscopy to estimate equilibrium association constans (Kas) for peptide‐micelle systems involving three peptides (leucine‐enkephalin, methionine‐enkephalin and leucine‐phenylalanine (LF)) and two surfactant micelles (sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)). Buffer pH was chosen to minimize purely electrostatic interactions between peptides and micelles that could not be interrogated by absorption spectroscopy. Viscosity‐corrected MEKC mobilities gave reasonably similar estimates of Kas between the two methods for all three peptide‐SDS micelle systems, with Kas values ranging from 13.7 ± 0.3 to 49 ± 1 M‐1. For CTAB, estimates of Kas for LF‐CTAB micelle association were of the same order of magnitude as the SDS micelle by the two methods of estimation. On the other hand, enkephalin‐CTAB micelle binding was about 10 times stronger (Kas = 122 ± 3 M‐1 to 311 ± 9 M‐1) than the enkephalin‐SDS micelle binding. In addition, MEKC underestimated the Kas values relative to spectroscopy by a factor of 2–3 for the enkephalin‐CTAB system.
Identification of degradation products of aspartyl tripeptides by capillary electrophoresis‐tandem mass spectrometry
Authors: Boni Silvia De , Neusüß Christian , Pelzing Matthias , Scriba Gerhard K. E.
Published: March 2003

Capillary electrophoresis‐electrospray tandem mass spectrometry (CE‐MS/MS) has been used to identify degradation products of the aspartyl tripeptides Phe‐Asp‐GlyNH2 and Gly‐Asp‐PheNH2 following incubation of the peptides in acidic and alkaline solution. At pH 2, the dominant decomposition products resulted from cleavage of the peptide backbone amide bonds to yield the respective dipeptides and amino acids. In addition, the cyclic aspartyl succinimide intermediate was identified by its [M+H]+ at m/z = 319 and the MS/MS spectrum exhibiting a simple fragmentation pattern with the [C8H10N]+‐ion as the principal daughter ion (a1 of Phe‐Asp‐GlyNH2). Deamidation of the C‐terminal amide as well as isomerization and enantiomerization of the Asp residue occurred upon incubation at pH 10. α‐Asp and the isomeric β‐Asp and most of the diastereomeric forms (corresponding to D/L‐Asp) could be separated by CE. All isomers could be identified based on their MS/MS spectra. Peptides with the amino acid sequence Phe‐Asp‐Gly containing the regular α‐Asp bond displayed a highly intense b2 fragment ion and a low abundant y2 ion. In contrast, the y2 and a1 fragment were high abundant daughter ions in the mass spectra of β‐Asp peptides while the b2 ion exhibited a lower abundance. Differences in the MS/MS spectra of the isomers of the peptides with the sequence Gly‐Asp‐Phe were obvious but less pronounced. In conclusion, CE‐MS/MS proved to be a useful tool to study the decomposition and enantiomerization of peptides including the isomerization of Asp residues, due to the combination of efficient separation of isomers by CE and their identification by MS/MS.
Variability in human sensitivity to 1,3‐butadiene: Influence of the allelic variants of the microsomal epoxide hydrolase gene
Authors: Abdel‐Rahman Sherif Z. , El‐Zein Randa A. , Ammenheuser Marinel M. , Yang Zhen , Stock Thomas H. , Morandi Maria , Ward Jonathan B.
Published: March 2003

The carcinogenic effects of 1,3‐butadiene (BD), a chemical widely used in the rubber industry, are thought to be due to its epoxide metabolites. In humans, these epoxides are detoxified predominantly by hydrolysis, a reaction mediated by the microsomal epoxide hydrolase (mEH) enzyme. The mEH gene is polymorphic and the most common mEH coding‐region variants detected in human populations are the two amino acid polymorphisms Tyr113His and His139Arg. Polymorphic amino acid substitutions at residues 113 and 139 in the human mEH protein can associate in four distinct combinations: Tyr113/His139, Tyr113/Arg139, His113/His139, and His113/Arg139. In vitro studies have shown that each of these genotypes has a unique mEH protein level that can affect net mEH enzymatic activity. In the current study, we examined the relationships among the genotypes involving these two polymorphisms and the mutagenic responses associated with occupational exposure to BD. We studied 49 nonsmoking workers from two styrene‐butadiene rubber facilities in southeast Texas using the autoradiographic HPRT mutant lymphocyte assay as a biomarker of genotoxic effect. We genotyped the study participants simultaneously for both polymorphisms, using a multiplex PCR assay developed in our laboratory, and the subjects were assigned to a specific group based on the predicted mEH activity associated with their genotypes (low, intermediate, and high). In the study population, 67% were exposed to low BD levels of <150 ppb (measured by personal badge dosimeters) and 33% were exposed to >150 ppb (mean 2,244 ppb). In the BD low‐exposure group, the mEH genotypes had no significant effect on the HPRT variant (mutant) frequency (Vf). In the high‐exposure group (BD > 150 ppb), individuals with genotypes associated with low mEH activity had a significant (P < 0.05) 3‐fold increase in HPRT Vf (Vf ± SEM = 13.95 ± 2.15 × 10−6) compared to high‐activity individuals (4.41 ± 1.19 × 10−6), and a 2‐fold increase in Vf compared to intermediate‐activity individuals (6.44 ± 2.09 × 10−6). Our results indicate that mEH genotypes may play a significant role in human sensitivity to the genotoxic effects of exposure to BD. Environ. Mol. Mutagen. 41:140–146, 2003. © 2003 Wiley‐Liss, Inc.
Time delayed control of structural systems
Authors: Udwadia Firdaus E. , von Bremen Hubertus F. , Kumar Ravi , Hosseini Mohammad
Published: March 2003

Time delays are ubiquitous in control systems. They usually enter because of the sensors and actuators used in them. Traditionally, time delays have been thought to have a deleterious effect on both the stability and the performance of controlled systems, and much research has been done in attempting to eliminate them, compensate for them, or nullify their presence. In this paper we take a different view. We investigate whether purposefully injected time delays can be used to improve both the system's stability and performance. Our analytical, numerical, and experimental investigation shows that this can indeed be done. Analytical results of the effects of time delays on collocated and non‐collocated control of classically damped and non‐classically damped systems are given. Experimental and numerical results confirm the theoretical expectations. Issues of system uncertainties and robustness of time delayed control are addressed. The results are of practical value in improving the performance and stability of controllers because these characteristics (performance and stability) improve dramatically with the intentional injection of small time delays in the control system. The introduction of such time delays constitutes a ‘minimal change’ to a controller already installed in a structural system for active control. Hence, from a practical standpoint, time delays can be implemented in a nearly costless and highly reliable manner to improve control performance and stability, an aspect that cannot be ignored when dealing with the economics and safety of large structural systems subjected to strong earthquake ground shaking. Copyright © 2003 John Wiley & Sons, Ltd.
Optimum multiple tuned mass dampers for structures under the ground acceleration based on the uniform distribution of system parameters
Authors: Li Chunxiang , Liu Yanxia
Published: March 2003

The five MTMD models, with natural frequencies being uniformly distributed around their mean frequency, have been recently presented by the first author. They are shown to have the near‐zero optimum average damping ratio (more precisely, for a given mass ratio there is an upper limit on the total number, beyond which the near‐zero optimum average damping ratio occurs). In this paper, the eight new MTMD models (i.e. the UM‐MTMD1∼UM‐MTMD3, US‐MTMD1∼US‐MTMD3, UD‐MTMD1 and UD‐MTMD2), with the system parameters (mass, stiffness and damping coefficient) being, respectively, uniformly distributed around their average values, have been, for the first time here, proposed to seek for the MTMD models without the near‐zero optimum average damping ratio. The structure is represented by the mode‐generalized system corresponding to the specific vibration mode that needs to be controlled. Through minimization of the minimum values of the maximum dynamic magnification factors (DMF) of the structure with the eight MTMD models (i.e. through the implementation of Min.Min.Max.DMF), the optimum parameters and values of Min.Min.Max.DMF for these eight MTMD models are investigated to evaluate and compare their control performance. The optimum parameters include the optimum mass spacing, stiffness spacing, damping coefficient spacing, frequency spacing, average damping ratio and tuning frequency ratio. The six MTMD models without the near‐zero optimum average damping ratio (i.e. the UM‐MTMD1∼UM‐MTMD3, US‐MTMD1, US‐MTMD2 and UD‐MTMD2) are found through extensive numerical analyses. Likewise, the optimum UM‐MTMD3 offers the higher effectiveness and robustness and requires the smaller damping with respect to the rest of the MTMD models in reducing the responses of structures subjected to earthquakes. Additionally, it is interesting to note, by comparing the optimum UM‐MTMD3 with the optimum MTMD‐1 recently investigated by the first author, that the effectiveness and robustness for the optimum UM‐MTMD3 is almost identical to that for the optimum MTMD‐1 (without inclusion of the optimum MTMD‐1 with the near‐zero optimum average damping ratio). Recognizing these performance benefits, it is preferable to employ the optimum UM‐MTMD3 or the optimum MTMD‐1 without the near‐zero optimum average damping ratio, when installing the MTMD for the suppression of undesirable oscillations of structures under earthquakes. Copyright © 2003 John Wiley & Sons, Ltd.
Airborne LiDAR in support of geomorphological and hydraulic modelling
Authors: French J. R.
Published: March 2003

This paper considers the application of airborne laser altimetry (LiDAR) to the provision of elevation data at accuracies and spatial densities commensurate with the current generation of high‐resolution hydraulic models. Three sets of issues are addressed with reference to a Telemac 2D model of a morphologically complex estuary in eastern England. First, the quality of airborne LiDAR data is assessed via multiscale calibration against surveyed sections and supplementary control points. Second, image processing techniques are used for (i) identification of multiple regions of interest within large LiDAR mosaics; (ii) subregional infilling of voids left by data ‘drop‐outs’; (iii) filtering and subsampling to match topographic information content with model resolution and the density of the computational mesh. Third, the implications of improved terrain data are considered with reference to the estimation of elevations and potential tidal volumes for a number of discrete flood compartments and the modelling of hypothetical inundation scenarios. After minor offset correction to ensure registration with local benchmarks, the quality of LiDAR elevation data within a 12 km × 4 km coverage is found to be consistent with the published specification (±0·10 to ±0·15 m). Image‐processing tools provide an efficient means of managing information content and interfacing this with the GIS‐based functionality of the pre‐processing software used in conjunction with the hydraulic model. The accuracy and spatial resolution of the LiDAR data allow the identification of subtle but important topographic variations between adjacent flood compartments. In many cases, differences in model results obtained using these data relative to previously estimated average flood compartment elevations are small. Importantly, however, LiDAR provides topographic information at an accuracy and resolution close to the present limits of model representation. Reliable representation of form allows the modeller to concentrate on the physical aspects of model parameterization, whilst minimizing the conflation of parameter effects with those of poorly constrained geometric representation. Copyright © 2003 John Wiley & Sons, Ltd.
Identifying critical technologies in the United States: a review of the federal effort
Authors: Wagner Caroline S. , Popper Steven W.
Published: March 2003

The United States government has not sponsored technology foresight as it has been defined and practised by governments in Europe, Japan and elsewhere in the world. [Foresight has been described in many places, but the original concept, as far as the authors are aware, was proposed by Martin and Irvine (1989).] [Different approaches to identifying important technologies is summarized in Wagner (1997).] Instead, the US government sponsored a parallel effort called ‘critical technologies identification’ between 1989 and 1999. This paper describes the critical technologies movement in the United States and explores why critical technologies identification was limited in its ability to capture the attention of US government officials and other decision‐makers. The authors suggest possible alternative futures for foresight in the United States. Copyright © 2003 John Wiley & Sons, Ltd.
Twelve lessons from ‘Key Technologies 2005’: the French technology foresight exercise
Authors: Durand Thomas
Published: March 2003

The paper draws lessons from the French technology foresight exercise ‘Key Technologies 2005’. It first describes the exercise as it took place: its context and objectives as well as the methodology that was adopted to identify, select and characterize 120 key technologies. Specifically, the paper describes the criteria used to select among the candidate key technologies, and then presents a specific tool which was developed to describe each technology (a characterization grid relating functional market needs and technological solutions to fulfil the generic need). Finally, twelve lessons are discussed. These deal with both the content of the foresight results and the methodology of running a technology foresight at national level. Copyright © 2003 John Wiley & Sons, Ltd.
An exploratory instrumental variable analysis of the outcomes of localized breast cancer treatments in a medicare population
Authors: Hadley Jack , Polsky Daniel , Mandelblatt Jeanne S. , Mitchell Jean M. , Weeks Jane C. , Wang Qin , Hwang Yi‐Ting ,   OPTIONS Research Team
Published: March 2003

This study is motivated by the potential problem of using observational data to draw inferences about treatment outcomes when experimental data are not available. We compare two statistical approaches, ordinary least‐squares (OLS) and instrumental variables (IV) regression analysis, to estimate the outcomes (three‐year post‐treatment survival) of three treatments for early stage breast cancer in elderly women: mastectomy (MST), breast conserving surgery with radiation therapy (BCSRT), and breast conserving surgery only (BCSO). The primary data source was Medicare claims for a national random sample of 2907 women (age 67 or older) with localized breast cancer who were treated between 1992 and 1994.

Contrary to randomized clinical trial (RCT) results, analysis with the observational data found highly significant differences in survival among the three treatment alternatives: 79.2% survival for BCSO, 85.3% for MST, and 93.0% for BCSRT. Using OLS to control for the effects of observable characteristics narrowed the estimated survival rate differences, which remained statistically significant. In contrast, the IV analysis estimated survival rate differences that were not significantly different from 0. However, the IV‐point estimates of the treatment effects were quantitatively larger than the OLS estimates, unstable, and not significantly different from the OLS results. In addition, both sets of estimates were in the same quantitative range as the RCT results.

We conclude that unadjusted observational data on health outcomes of alternative treatments for localized breast cancer should not be used for cost‐effectiveness studies. Our comparisons suggest that whether one places greater confidence in the OLS or the IV results depends on at least three factors: (1) the extent of observable health information that can be used as controls in OLS estimation, (2) the outcomes of statistical tests of the validity of the instrumental variable method, and (3) the similarity of the OLS and IV estimates. In this particular analysis, the OLS estimates appear to be preferable because of the instability of the IV estimates. Copyright © 2002 John Wiley & Sons, Ltd.
High‐frequency oscillation in the hippocampus of the behaving rat and its modulation by the histaminergic system
Authors: Knoche A. , Yokoyama H. , Ponomarenko A. , Frisch C. , Huston J. , Haas H.L.
Published: March 2003

The histaminergic neurons located in the posterior hypothalamus modulate whole brain activity in a manner dependent on behavioral state. We have investigated their influence on high‐frequency oscillation (200‐Hz ripples) in the hippocampal CA1 region of freely moving rats. The occurrence of these ripples, assumed to be involved in memory trace formation, was markedly enhanced after injection of the H1‐antagonists pyrilamine and ketotifen in a lateral ventricle, indicating a tonic activity of the histaminergic system. The H2‐ and H3‐antagonists cimetidine and thioperamide were ineffective. We suggest a mediation of these effects through blocking the known histaminergic excitation of septal neurons. Histamine administered by the intracerebroventricular route had an inhibitory action on ripples. H1‐receptor activation, which has been shown to inhibit learning and memory, thus shifts hippocampal activity away from high‐frequency oscillation toward theta activity. Hippocampus 2003;13:273–280. © 2003 Wiley‐Liss, Inc.
Navigation expertise and the human hippocampus: A structural brain imaging analysis
Authors: Maguire Eleanor A. , Spiers Hugo J. , Good Catriona D. , Hartley Tom , Frackowiak Richard S.J. , Burgess Neil
Published: March 2003

Grey matter volume in the posterior hippocampus of London taxi drivers is greater than in age‐matched controls, and the size of this increase correlates positively with time spent taxi driving (E.A. Maguire et al., 2000. Proc Natl Acad Sci U S A 97: 4398–4403). This change suggests that increased posterior hippocampal grey matter volume is acquired in response to increased taxi driving experience, perhaps reflecting their detailed representation of the city. However, an alternate hypothesis is that the difference in hippocampal volume is instead associated with innate navigational expertise, leading to an increased likelihood of becoming a taxi driver. To investigate this possibility, we used structural brain imaging and voxel‐based morphometry (VBM) to examine a group of subjects who were not taxi drivers. Despite this group showing a wide range of navigational expertise, there was no association between expertise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain). This failure to find an association between hippocampal volume and navigational expertise thus suggests that structural differences in the human hippocampus reflect the detail and/or duration of use of the spatial representation acquired, and not innate navigational expertise per se. Hippocampus 2003;13:250–259. © 2003 Wiley‐Liss, Inc.
Direct Spectroscopic Evidence that the Photochemical Outcome of Flutamide in a Protein Environment is Tuned by Modification of the Molecular Geometry: A Comparison with the Photobehavior in Cyclodextrin and Vesicles
Authors: Sortino Salvatore , Petralia Salvatore , Condorelli Giuseppe , Marconi Giancarlo
Published: March 2003

The photoreactivity of the phototoxic anticancer drug flutamide (FM) in the presence of bovine serum albumin (BSA) has been investigated. The presence of BSA induces a remarkable modification of the photochemical outcome of the drug with respect to that observed in aqueous solution. Induced circular dichroism (ICD) measurements combined with theoretical calculations provide strong evidence that the new photochemical scenario is tuned by changes of the molecular geometry of FM when incorporated in the protein microenvironment. This behavior presents close analogies to that found in the presence of either cyclodextrin or phospholipid vesicles, chosen as models for biological systems, and delineates a quite general photochemical picture that can be useful for a more appropriate understanding of the adverse phototoxic effects induced by this drug.
New Acetylcholinesterase‐Inhibitory Pregnane Glycosides of Cynanchum atratum Roots
Authors: Lee Ki Yong , Sung Sang Hyun , Kim Young Choong
Published: March 2003

Three new pregnane glycosides, cynatroside A (1), cynatroside B (2), and cynatroside C (3), isolated from the roots of Cynanchum atratum (Asclepiadaceae), were characterized as 7β‐{[O‐α‐L‐cymaropyranosyl‐(1→4)‐O‐β‐D‐digitoxopyranosyl‐(1→4)‐β‐D‐oleandropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐6α‐hydroxy‐4b‐ methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (1), 7β‐{[O‐β‐D‐cymaropyranosyl‐(1→4)‐O‐α‐L‐diginopyranosyl‐(1→4)‐β‐D‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (2), and 7β‐{[O‐α‐L‐cymaropyranosyl‐(1→4)‐O‐β‐D‐digitoxopyranosyl‐(1→4)‐β‐L‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (3), respectively. In addition, ten known constituents were identified, i.e., cynascyroside D (4), glaucoside C (5), glaucoside D (6), atratoside A (7), 2,4‐dihydroxyacetophenone (8), 4‐hydroxyacetophenone (9), syringic acid (10), azelaic acid (11), suberic acid (12), and succinic acid (13). Among these compounds, 1–4 significantly inhibit acetylcholinesterase activity.
Probes for Narcotic Receptor Mediated Phenomena
Authors: Linders Joannes T. M. , Mirsadeghi Seid , Flippen‐Anderson Judith L. , George Clifford , Jacobson Arthur E. , Rice Kenner C.
Published: March 2003

The synthesis of a series of epoxy 5‐phenylmorphans is being explored in order to determine the conformational requirements of the phenolic ring in a phenylmorphan molecule that may be needed both for binding to a specific opioid receptor and for exhibiting opioid agonist or antagonist activity. Of the twelve possible ortho‐ and para‐bridged isomers (a–f) (Fig. 1), we now report the synthesis of the para‐d isomer, rac‐(3R,6aS,11aR)‐2‐methyl‐1,3,4,5,6,11a‐hexahydro‐2H‐3,6a‐methanobenzofuro[2,3‐c]azocin‐8‐ol (3). Compound 3 was synthesized via construction of the 5‐phenylazabicyclo[3.3.1]non‐3‐ene skeleton (Scheme 1) and subsequent closure of the epoxy bridge (Scheme 2). As determined by an X‐ray diffraction study, the epoxy bridge, restricting the phenyl‐ring rotation, fixed the dihedral angle between the least‐squares planes through the phenyl ring and atoms N(2), C(3), C(11a), and C(6a) of the piperidine ring (Fig. 2) at 43.0°, and the torsion angle C(12)C(6a)C(6b)C(10a) at −95.0°.
New Acylated Preatroxigenin Saponins from Atroxima congolana
Authors: Elbandy Mohamed , Miyamoto Tomofumi , Delaude Clément , Lacaille‐Dubois Marie‐Aleth
Published: March 2003

Eight new acylated preatroxigenin saponins 1–8 were isolated as four inseparable mixtures of the trans‐ and cis‐4‐methoxycinnamoyl derivatives, atroximasaponins A1/A2 (1/2), B1/B2 (3/4), C1/C2 (5/6) and D1/D2 (7/8) from the roots of Atroxima congolana. These compounds are the first examples of triterpene saponins containing preatroxigenin (=(2β,3β,4α,22β)‐2,3,22,27‐tetrahydroxyolean‐12‐ene‐23,28‐dioic acid as aglycone. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR studies and FAB‐MS as 3‐O(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranoyl} ester (1) and its cis‐isomer 2, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→ 2)‐O‐[O‐6‐O‐acetyl‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐ 4‐methoxycinnamoyl)‐β‐D‐fucopyranosyl} ester (3) and its cis‐isomer 4, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐[β‐D‐apiofuranosyl‐(1→3)]‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐6‐ O‐acetyl‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranoyl} ester (5) and its cis‐isomer 6, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐[β‐D‐apiofuranosyl‐(1→3)]‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐β‐D‐xylopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranosyl ester (7) and its cis‐isomer 8.
The impact of financial constraints and incentives on professional autonomy
Authors: Lewis Jenny M. , Marjoribanks Tim
Published: March 2003

General practice has been the subject of extensive reforms over the 1990s in Australia as elsewhere. Reforms have attempted to improve quality and contain the overall cost of health care, and have often been seen as reducing the autonomy of medical professionals. This paper examines the impact of financial constraints and incentives introduced during the 1990s on Australian GPs' perceptions of autonomy. An existing seven component definition of autonomy and six themes that emerged from reviewing publications were used to construct focus group questions. A total of 25 GPs participated in four focus groups. Those who participated believe that their financial autonomy has been diminished by policy changes and consumer expectations. They also perceive that their ability to control clinical decisions, which they regard as the most important aspect of professional autonomy, has been reduced along with financial autonomy. Organized medicine in Australia sees financial accountability and clinical decision making as polar opposites, and has continued to argue that fee‐for‐service payment is the only appropriate method of remuneration, despite increasing evidence that this does not guarantee clinical autonomy. Major changes to the financing of general practice in Australia are required to address the concerns of GPs, governments and patients. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical simulation of overbank processes in topographically complex floodplain environments
Authors: Nicholas A. P. , Mitchell C. A.
Published: March 2003

This article presents results from an investigation of the hydraulic characteristics of overbank flows on topographically‐complex natural river floodplains. A two‐dimensional hydraulic model that solves the depth‐averaged shallow water form of the Navier–Stokes equations is used to simulate an overbank flow event within a multiple channel reach of the River Culm, Devon, UK. Parameterization of channel and floodplain roughness by the model is evaluated using monitored records of main channel water level and point measurements of floodplain flow depth and unit discharge. Modelled inundation extents and sequences are assessed using maps of actual inundation patterns obtained using a Global Positioning System, observational evidence and ground photographs. Simulation results suggest a two‐phase model of flooding at the site, which seems likely to be representative of natural floodplains in general. Comparison of these results with previous research demonstrates the complexity of overbank flows on natural river floodplains and highlights the limitations of laboratory flumes as an analogue for these environments. Despite this complexity, frequency distributions of simulated depth, velocity and unit discharge data closely follow a simple gamma distribution model, and are described by a shape parameter (α) that exhibits clear systematic trends with changing discharge and floodplain roughness. Such statistical approaches have the potential to provide the basis for computationally efficient flood routing and overbank sedimentation models. Copyright © 2002 John Wiley & Sons, Ltd.
A tracer‐based assessment of hydrological pathways at different spatial scales in a mesoscale Scottish catchment
Authors: Soulsby C. , Rodgers P. , Smart R. , Dawson J. , Dunn S.
Published: March 2003

Geochemically based hydrograph separation techniques were used in a preliminary assessment to infer how runoff processes change with landscape characteristics and spatial scale (1–233 km2) within a mesoscale catchment in upland Scotland. A two‐component end‐member mixing analysis (EMMA) used Gran alkalinity as an assumed conservative tracer. Analysis indicated that, at all scales investigated, acidic overland flow and shallow subsurface storm flows from the peaty soils covering the catchment headwaters dominated storm runoff generation. The estimated groundwater contribution to annual runoff varied from 30% in the smallest (ca 1 km2) peat‐dominated headwater catchment with limited groundwater storage, to >60% in larger catchments (>30 km2) with greater coverage of more freely draining soils and more extensive aquifers in alluvium and other drift. This simple approach offers a useful, integrated conceptualization of the hydrological functioning in a mesoscale catchment, which can be tested and further refined by focused modelling and process‐based research. However, even as it stands, the simple conceptualization of system behaviour will have significant utility as a tool for communicating hydrological issues in a range of planning and management decisions. Copyright © 2002 John Wiley & Sons, Ltd.
The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes
Authors: Siegert Martin J. , Tranter Martyn , Ellis‐Evans J. Cynan , Priscu John C. , Berry Lyons W.
Published: March 2003

Our understanding of Lake Vostok, the huge subglacial lake beneath the East Antarctic Ice Sheet, has improved recently through the identification of key physical and chemical interactions between the ice sheet and the lake. The north of the lake, where the overlying ice sheet is thickest, is characterized by subglacial melting, whereas freezing of lake water occurs in the south, resulting in ∼210 m of ice accretion to the underside of the ice sheet. The accreted ice contains lower concentrations of the impurities normally found in glacier ice, suggesting a net transfer of material from meltwater into the lake. The small numbers of microbes found so far within the accreted ice have DNA profiles similar to those of contemporary surface microbes. Microbiologists expect, however, that Lake Vostok, and other subglacial lakes, will harbour unique species, particularly within the deeper waters and associated sediments. The extreme environments of subglacial lakes are characterized by high pressures, low temperatures, permanent darkness, limited nutrient availability, and oxygen concentrations that are derived from the ice that provides the meltwater. Copyright © 2002 John Wiley & Sons, Ltd.
The new accountability: From regulation to results
Authors: Burke Joseph C. , Minassians Henrik P
Published: March 2003

In the 1990s, the focus of accountability for higher education shifted from regulation to results. It spurred the popularity of performance funding, budgeting, and reporting in state capitols, although not on college campuses.
Performance reports: Coverage and customers, purposes and priorities
Authors: Burke Joseph C. , Minassians Henrik P
Published: March 2003

Although allegedly addressing state, campuses, and opinion leaders, many performance reports were so long and dense that they discouraged readers. Readability was important, because reports had to persuade skeptics that external accountability and institutional improvement were complementary—not conflicting—goals.
Electrochemical deposition of hydroxyapatite with vinyl acetate on titanium implants
Authors: Hu Haobing , Lin Changjian , Lui Pauline Po Yee , Leng Yang
Published: March 2003

A novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl acetate was added in the electrolytes of calcium and phosphorous in order to improve the adhesion between HA coating and titanium substrate. X‐ray powder diffractometer (XRD) spectra indicated that the vinyl acetate did not interfere with the deposition of HA on the surface of titanium cathodes. X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results revealed that both vinyl acetate and HA were deposited on the titanium cathodes. The vinyl acetate changed the HA crystalline morphology in the deposition layer. The shape and growth direction of the HA crystals in the coating with vinyl acetate differed from those of HA deposition along. The addition of vinyl acetate increased the coating strength considerably, even though further improvement is needed for clinical applications. Moreover, a preliminary study of the bioactivity showed that osteoblastic cells exhibited higher cell proliferation potential on the HA/vinyl acetate coating than on that of pure HA. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 24–29, 2003
Comparative evaluation of the osteoinductivity of two formulations of human demineralized bone matrix
Authors: Takikawa Satoshi , Bauer Thomas W. , Kambic Helen , Togawa Daisuke
Published: March 2003

In the United States, demineralized bone matrix (DBM) is considered a transplantable tissue and therefore is regulated primarily by the American Association of Tissue Banks. Even though DBM is not subjected to the same regulations relative to performance claims as medical devices are, one would expect different processing methods might yield DBM preparations of different osteoinductive potential. The purpose of this study was to use an established athymic rat model to compare the osteoinductive properties of two commercially available human DBMs prepared using different methods but having essentially identical product claims. Sixteen female athymic rats were used to test equivalent volumes of two lots each of Grafton Putty® (Osteotech, Inc., Eatontown, NJ), Osteofil® (Regeneration Technologies, Inc., Alachua, FL), and rat DBM. At 28 days after implantation, qualitative and semiquantitative microscopy showed no significant differences in bone formation between the two lots from each source, but rat DBM produced significantly more bone than Grafton®, which produced significantly more bone than Osteofil®. Our results suggest that methods of graft processing may represent a greater source of variability than do differences among individual donors. Whether these differences relate to methods of demineralization, carrier, dose of DBM per volume, or to some other factor remains to be determined. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 37–42, 2003
In vivo bone response to porous calcium phosphate cement
Authors: del Real R. P. , Ooms E. , Wolke J. G. C. , Vallet‐Regí M. , Jansen J. A.
Published: March 2003

We conducted an in vivo experiment to evaluate the resorption rate of a calcium phosphate cement (CPC) with macropores larger than 100 μm, using the CPC called Biocement D (Merck Biomaterial, Darmstadt, Germany), which after setting only shows pores smaller than 1 μm. The gas bubble method used during the setting process created macroporosity. Preset nonporous and porous cement implants were inserted into the trabecular bone of the tibial metaphysis of goats. The size of the preset implants was 6 mm and the diameter of the drill hole was 6.3 mm, leaving a gap of 0.3 mm between implant surface and drill wall. After 2 and 10 weeks, the animals were euthanized and cement implants with surrounding bone were retrieved for histologic evaluation. Light microscopy at 2 weeks revealed that the nonporous implants were surrounded by connective tissue. On the cement surface, we observed a monolayer of multinucleated cells. Ten weeks after implantation, the nonporous implants were still surrounded by connective tissue. However, a thin layer of bone now covered the implant surface. No sign of cement resorption was observed. In contrast, the porous cement evoked a completely different bone response. At 2 weeks, bone formation had already occurred inside the implant porosity. Bone formation even appeared to occur as a result of osteoinduction. Also, at their outer surface, the porous implants were completely surrounded by bone. At 2 weeks, about 31% of the initial cement was resorbed. After 10 weeks, 81% of the initial phosphate cement was resorbed and new bone was deposited. On the basis of these observations, we conclude that the creation of macropores can significantly improve the resorption rate of CPC. This increased degradation is associated with almost complete bone replacement. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 30–36, 2003