bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Behavior and Detection of Dopamine and Ascorbic Acid at an Iron(II)tetrasulfophthalocyanine Modified Carbon Paste Microelectrode
Authors: Oni Joshua , Westbroek Philippe , Nyokong Tebello
Published: July 2003

In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half‐wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
An Electroanalytical Investigation on the Redox Properties of Calcium Antagonist Dihydropyridines
Authors: Toniolo Rosanna , Tubaro Franco , Ursini Fulvio , Bontempelli Gino
Published: July 2003

The antioxidant capacity of some calcium antagonists and one calcium agonist 1,4‐dihydropyridines (DHPs) was evaluated by a competitive kinetic procedure. With the exception of Amlodipine, all the calcium antagonist DHPs display an unambiguous antioxidant capacity, while for the calcium agonist DHP (Bay K 8644) no measurable reactivity towards peroxyl radicals could be detected. The finding was corroborated by an electroanalytical investigation of the redox properties of DHPs compounds to get an insight about both the thermodynamic constraints of their oxidation process and reaction pattern. The oxidation potentials decrease with both antioxidant capacity and increasing basic character, thus suggesting the relevance of the electron density on the DHP ring. For all the compounds investigated, the overall oxidation process takes place through a primary one‐electron step accompanied by a fast proton release and the formation of a neutral radical undergoing a second much easier one‐electron step. The protonated form of the parent pyridine derivative is thus generated as the final product. This pattern is relevant for the antioxidant effect, since the radical intermediate is much more prone to be oxidized than to be reduced, thus fully preventing the propagation of the oxidative chain reaction. In the case of calcium antagonist DHPs, the above release of protons complicates the overall oxidation process by introducing a parasitic side reaction where a coupling between protons and the starting species takes place. This DHP self‐protonation subtracts part of the original species from the electrode process because the parent cationic species is no longer electroactive. Conversely, the calcium agonist DHP, which is more difficult to be oxidized, turned out to be such a weak base as to be unable to undergo the self‐protonation reaction. The combined effect of oxidation potentials and proton binding capacity of DHPs is a key element for the redox transition, which could support their antioxidant effect and should be considered to some extent in accounting for the calcium antagonist vs calcium agonist effect.
Microchip Separation and Electrochemical Detection of Amino Acids and Peptides Following Precolumn Derivatization with Naphthalene‐2,3‐dicarboxyaldehyde
Authors: Wang Joseph , Chen Gang , Pumera Martin
Published: July 2003

An integrated microfluidic device is used to derivatize, separate, and amperometrically detect amino acids and peptides in the presence of naphthalene‐2,3‐dicarboxyaldehyde (NDA). The integrated system offers a rapid (4 min) simultaneous measurements of 5 amino acids (Arg, Lys, Gly, Cys, PhenA) down to the 3.2 μM level in connection to a precolumn reaction chamber, an electrophoretic separation channel, and an end‐column thick‐film carbon‐electrode detector. The effect of the separation voltage, detection potential, reagent concentration, and other variables on the response is examined. Calibration and precision experiments indicate a linear and reproducible response. Applicability for the separation and detection of small peptides is demonstrated. Such on‐chip generation of electroactive products offers great promise for detecting other nonelectroactive analytes.
Determination of Chlorides in Meat Products with Ion‐Selective Electrode Using the Batch Injection Technique
Authors: Šucman Emanuel , Bednář Jiří
Published: July 2003

A procedure was developed for determination of salt in various meat products using a chloride ion‐selective electrode. The technique of batch injection analysis was used together with an ultrasound based sample extraction step. Various kinds of meat products were analyzed. The relative standard derivation lies between 0.9% and 2.7%. The accuracy of the method was proved by an independent reference method. Differences between the results of the batch injection analysis method and the reference method were found to be statistically non‐significant. Total analysis time was 7 minutes on average. The described batch injection analysis method is fast, accurate, reliable and suitable for routine analytical work.
Polymeric ISE for Hydrogen Sulfite Based on Bis‐Urea Calix[4]diquinones as Neutral Lipophilic Ionophores
Authors: Jeon Seungwon , Yeo Heekyoung , Jeong Haesang , Min Oh Jung , Chun Nam Kye
Published: July 2003

A new PVC membrane electrode for HSO3− anion based on bis‐urea calix[4]diquinones I–VI as neutral ionophores is prepared. Of the various membranes prepared, the membrane based on calix[4]diquinone III exhibits a linear stable response over a wide concentration range (6.0×10−5−1.0×10−2) with a slope of −51.5 mV/decade and a detection limit of 2.2×10−6 M. With the exception of HSO3− anion, the remainder of the anions responds based on their hydrophobicity. The membrane revealed improved selectivity coefficients for HSO3− over a wide variety of other anions, and the comparable selectivity for the HSO3−selective membranes is iodide anion.
Some Electrochemical Characteristics of Boron‐ and Phosphorus‐Doped Glassy Carbon Electrodes
Authors: Abramović Biljana F. , Bjelica Luka J. , Gaál Ferenc F. , Guzsvány Valéria J. , Jovanovic Ljiljana S.
Published: July 2003

Three glassy carbon (GC) samples: undoped and doped with boron or phosphorus, prepared at 1000 °C, were compared in respect to hydrodynamic current‐potential curves in acidic medium, cyclic voltammograms for Fe3+/2+ and Fe(CN)63−/4− and argentometric titrations of halides. Some experiments were also carried out using standard Tokai and Sigri GC and Ag electrode. It appeared that GC doped with boron and phosphorus exhibited significant increase in hydrogen evolution overpotential. As for the electrode kinetics (ΔEp criterion), no significant difference was observed between doped and undoped electrodes. In the potentiometric titrations the phosphorus‐doped electrode was advantageous over the other GC and Ag electrodes as it enabled more precise end‐point detection.
Electrochemical Reduction of a Conjugated Cinnamic Acid Diazonium Salt as an Immobilization Matrix for Glucose Biosensor
Authors: Yang Xinhao , Hall Simon B. , Ngin Tan Swee
Published: July 2003

Initial results on the synthesis of a new conjugated diazonium salt of trans‐4‐cinnamic acid diazonium fluoroborate, which is used for the chemical modification of the glassy carbon (GC) electrode with trans‐4‐cinnamic acid groups through electrochemical reduction, and direct covalent immobilization of glucose oxidase (GOD) on the cinnamic acid groups are presented. The chemically modified GC electrode exhibits a good selectivity relative to the bare GC electrode for the various possible interfering compounds in glucose analysis: namely ascorbic acid and 4‐acetamidophenol. Covalent immobilization of GOD on the chemically modified GC electrode produces a biosensor which responds to glucose concentration changes in the presence of a soluble redox mediator (ferrocenemethanol). The chemical modification of GC by cinnamic acid groups is potentially useful for the attachment of other enzymes and biochemical reagents.
In Vivo Monitoring of the Thiols in Rat Striatum by Liquid Chromatography with Amperometric Detection at a Functionalized Multi‐Wall Carbon Nanotubes Modified Electrode
Authors: Cao Xu‐Ni , Lin Li , Xian Yue‐Zhong , Zhang Wen , Xie Yun‐Feng , Jin Li‐Tong
Published: July 2003

A new chemically modified electrode (CME) was fabricated, which was based on the immobilization of multi‐wall carbon nanotubes fuctionalized with carboxylic group (MWNT‐COOH). The results indicated that the CME exhibited efficiently electrocatalytic oxidation for L‐cysteine and glutathione with relatively high sensitivity, stability and long‐life. Coupled with HPLC, the MWNT‐COOH CME was utilized for amperometric detection of the thiols. The peak currents of L‐cysteine and glutathione were linear to their concentrations ranging from 3.0×10−7 to 1.0×10−3 mol/L with the calculated detection limit (S/N=3) of 1.2×10−7, 2.2×10−7 mol/L, respectively. The method had been successfully applied to assess the contents of L‐cysteine and glutathione in rat striatal microdialysates.
Determination of Taurine inLycium Barbarum L.and Other Foods by Capillary Electrophoresis with Electrochemical Detection
Authors: Cao Yuhua , Zhang Xin , Chu Qingcui , Fang Yuzhi , Ye Jiannong
Published: July 2003

A method based on capillary electrophoresis (CE) with electrochemical detection (ED) was developed for the determination of taurine inLycium Barbarum L., LIPOVIYAN beverage and milk powder. The effects of some important factors such as the acidity of the running buffer, separation voltage, injection time, and applied potential to working electrode were investigated. Operated in a wall‐jet configuration, a 300 μm diameter carbon‐disk electrode was used as the working electrode, which exhibits good responses at +1.05 V (vs. SCE) for taurine. Excellent linearity was obtained in the concentration range from 5.0×10−4 mol/L to 5.0×10−6 mol/L. The detection limit (S/N=3) was 1.0×10−7 mol/L. This proposed method has been successfully applied to analyze the actual samples with satisfactory assay results.
An Electrochemical Investigation of Complexation of Pb(II) by a Well‐Characterized Fulvic Acid in Model Systems – Effect of Competition with Major Cations and Trace Metals
Authors: Mandal Rupasri , Salam Mohamed S. A. , Chakrabarti Chuni L. , Back Margaret H.
Published: July 2003

Effect of competition of major cations, Ca2+, Mg2+, and trace metals, Cu2+, Ni2+ and Zn2+, on the stability of the Pb(II)‐fulvic acid (FA) complexes in model systems at constant pH and ionic strength was investigated by square‐wave anodic stripping voltammetry (SWASV). The results show that the trace metals compete with the target trace metal, Pb(II), for binding sites of the FA even when they are present in the same concentration as that of Pb(II), whereas the major cations compete with Pb(II) only when they are present in massive excess.
Empirical scrutiny of a familiar narrative: sense of control in anorexia nervosa
Authors: Surgenor Lois J. , Horn Jacqueline , Hudson Stephen M.
Published: June 2003

Psychological control has been hypothesized to play a pivotal role in the variability, natural course, and treatment of anorexia nervosa (AN). However both the empirical and theoretical literatures suggest that this relationship is incompletely understood. Employing a multidimensional control inventory to overcome problems identified in previous research, this study examines the relationship between psychological sense of control and clinical variability of AN in 51 women. An adverse overall sense of control, along with reliance on specific means of gaining control was associated with more severe eating disturbance. Greater use of a negative‐assertive style of gaining control was associated with a longer time since first diagnosis, while desire for control was significantly associated with menstrual status. Finally, self‐induced vomiting was associated with specific means of obtaining control, while use of laxatives was associated with reduced control in the domain of body. Such findings have implications for future research and the application of control constructs in treatment. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
The role of biodevelopmental and psychological factors in disordered eating among adolescent males and females
Authors: McCabe M. P. , Vincent M. A.
Published: June 2003

The present study examined the role of biodevelopmental and psychological factors in the development of disordered eating in early adolescent males and females. Three hundred and six girls (mean age = 13.66 years; SD = 1.12 years) and 297 boys (mean age = 13.89 years; SD = 1.13 years) from grades 7–10 completed a questionnaire which assessed disordered eating, biodevelopmental (body mass index (BMI), age and puberty) and psychological factors (self‐esteem, depression, anxiety, ineffectiveness, perfectionism). Not surprisingly, girls were more likely than boys to engage in extreme weight loss behaviours. There were no significant differences between boys and girls on measures of binge eating or bulimic tendencies. Self‐esteem, depression and anxiety were found to be significant predictors of disordered eating among girls, while anxiety, ineffectiveness, self‐esteem and perfectionism were significant predictors among boys. The findings from this study demonstrate the importance of psychological variables in predicting extreme weight loss behaviours among both adolescent males and females. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
Can educational programmes raise clinical competence in treating eating disorders? Results from a Norwegian trial
Authors: Rosenvinge Jan H. , Skårderud Finn , Thune‐Larsen Kari‐Brith
Published: June 2003

This paper describes the structure and content of a Norwegian educational programme—‘Body and self‐esteem’—to raise clinical competence among health professionals treating patients with eating disorders. Apart from the individual competence, the aim of the programme is also to increase system‐based competence by forming network groups. Using a pre–post design, the programme's effectiveness is described covering the first 78 participants with respect to competence changes, professional attitudes toward treatment, satisfaction with the programme and dissemination effects. At the end of the programme, statistically significant changes in clinical competence were found. The participant's satisfaction was generally good, particularly with respect to gaining more theoretical knowledge and understanding and clinical skills training. Along with preliminary dissemination findings, the programme would appear to be highly promising. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
A comparison of clinical and psychological features in subgroups of patients with anorexia nervosa
Authors: Oliosi Manuela , Dalle Grave Riccardo
Published: June 2003

Background:

In DSM‐IV anorexics who purge without binging (AN‐P) are considered together with the binge eating purging subgroup (AN‐B). Few studies have investigated whether it is binge eating per se or the compensatory behaviours that provide the most relevant marker for subclassifying anorexia nervosa.

Methods:

We compared 40 restricting‐type anorexics (AN‐R), 40 AN‐B and 38 AN‐P subjects consecutively admitted to our inpatient treatment. We excluded patients who had not had a diagnosis of anorexia nervosa for at least 1.5 years duration.

Results:

AN‐B patients showed a slightly more severe eating disorder symptomatology, while in terms of body weight AN‐R and AN‐P present a higher degree of weight loss. Psychiatric symptoms were similar in the three groups. Sexual abuse, suicide attempts and dissociative symptoms were higher in AN‐P and AN‐B patients compared to AN‐R.

Discussion:

Our results together with the fact that it is difficult to define binge eating in anorexic subjects and that purging behaviours are often associated with severe medical complications, support the subtyping system of anorexia nervosa based on the presence/absence of purging behaviours rather than of binge eating. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
Bulimia Nervosa: A Cognitive Therapy Programme for Clients by Myra Cooper, Gillian Todd and Adrian Wells. European Eating Disorders Review, 2003; 11: 72
Authors: Baxter Helen
Published: June 2003

The original article to which this Erratum refers was published in European Eating Disorders Review 11(1) 2003, 72.
A Vygotskian Perspective on Youth Participatory Evaluation
Authors: Sabo Kim
Published: July 2003

Through five case studies, this chapter uses a Vygotskian perspective to frame youth participatory evaluation as both developmental and performatory.
Listening to the Experts
Authors: Voakes Les
Published: July 2003

A uniquely organized conference served as a tool for participatory evaluation. Positive youth development practices were empowering, and youth and adults worked as democratic equals in achieving common goals.
Youth‐Led Research and Evaluation: Tools for Youth, Organizational, and Community Development
Authors: London Jonathan K. , Zimmerman Kristen , Erbstein Nancy
Published: July 2003

This chapter provides case studies and discussion about the ways that youth‐led research and evaluation can help link youth and community development goals and outcomes.
Collaborating on Evaluation for Youth Development
Authors: Lau Genevieve , Netherland Nancy H. , Haywood Mary L.
Published: July 2003

Youth workers acquire evaluation skills to improve professional practice and then empower youth by teaching them how to evaluate their own experiences.
Using Participatory Methods to Further the Democratic Goals of Children's Organizations
Authors: Hart Roger A. , Rajbhandary Jasmine
Published: July 2003

This chapter describes and evaluates participatory methods that were developed to enable children in Nepal to document and reflect on the democratic functioning of their own organizations. It concludes with an assessment of the potentials of participatory methods for self‐monitoring by democratic organizations of young people.
All Stars Talent Show Network: Grassroots Funding, Community Building, and Participatory Evaluation
Authors: Gildin Bonny L.
Published: July 2003

The grassroots‐funding model of the All Stars Talent Show Network provides a uniquely supportive context for an innovative participatory evaluation process.
Youth and Evaluation: Empowered Social‐Change Agents
Authors: David Fetterman
Published: July 2003

Reflections on participatory evaluation with young people are offered.
Development of optimized weighted‐ENO schemes for multiscale compressible flows
Authors: Ponziani D. , Pirozzoli S. , Grasso F.
Published: July 2003

The present paper deals with the development of optimized weighted–ENO schemes to improve the resolution of a class of compressible flows characterized by a wide disparity of scales, typical of compressible turbulence and/or aeroacoustic phenomena, and shock waves. The approach relies on a least square minimization of both the dispersion and dissipation error components together with the use of symmetric stencil support. Extensive numerical simulations of sound propagation, shock–sound interaction and isotropic compressible turbulence have been carried out, and the results confirm that the optimized schemes yield a resolution in wave number space greater than the non‐optimized ones. Copyright © 2003 John Wiley & Sons, Ltd.
Near‐wall turbulence modelling with enhanced dissipation
Authors: Rahman M. M. , Siikonen T.
Published: July 2003

A low‐Reynolds number k–ε turbulence model is proposed that incorporates diffusion terms and modified Cε(1,2) coefficients to amplify the level of dissipation in non‐equilibrium flow regions, thus reducing the kinetic energy and length scale magnitudes to improve prediction of adverse pressure gradient flows, involving flow separation and reattachment. Unlike the conventional k–ε model, it requires no wall function/distance parameter that bridges the near‐wall integration. The model is validated against a few flow cases, yielding predictions in good agreement with the direct numerical simulation (DNS) and experimental data. Copyright © 2003 John Wiley & Sons, Ltd.
Direct testing of subgrid scale models in large‐eddy simulation of a non‐isothermal turbulent jet
Authors: Gago C. Ferreira , Garnier F. , Utheza F.
Published: July 2003

A comparative assessment of subgrid models of compressible large‐eddy simulations is performed for a temporally evolving heated round jet at a low Mach number. Initially, the temperature difference with respect to the ambient is chosen according to the one at the nozzle exit of a typical aircraft engine. Subgrid modelling in both the momentum and the energy equations is then necessary to close the problem. As basic models, we have considered the compressible versions of the Smagorinsky model, the mixed‐scale model (which can be defined as a dynamic‐type model) and the similarity model. The first two models are also supplemented with the similarity model or/and a selective function. Large‐eddy simulations (LES) results are compared with those obtained from a direct numerical simulation (DNS). Thus to allow correspondence between DNS and LES the Reynolds number, in the present study, is still not very high and equal to 500. Among the cases investigated the hybrid Smagorinsky model (linear combination of the Smagorinsky model and the similarity model) displays the best performances, especially when dealing with the turbulent stresses and the turbulent heat flux. Copyright © 2003 John Wiley & Sons, Ltd.
Pricing models of equity swaps
Authors: Wang Ming‐Chieh , Liao Szu‐Lang
Published: June 2003

This article provides a generalized formula for pricing equity swaps with constant notional principal when
the underlying equity markets and settlement currency can be set arbitrarily. To derive swap values using the
risk‐neutral valuation method, the swap payment is replicated at each settlement date by constructing a
self‐financing portfolio. To obtain the foreign equity index return denominated in the domestic or in a
third currency, equity‐linked foreign exchange options are used to hedge the exchange rate risk. It is
found that if the swap involves international equity markets, then the swap value contains an extra term which
reflects the currency hedging costs. This methodology can easily be applied to price various types of equity
swaps simply by modifying the specifications of the model presented here as required. © 2003 Wiley
Periodicals, Inc. Jrl Fut Mark 23:751–772, 2003
Scheduled announcements and volatility patterns: The effects of monetary policy committee announcements on LIBOR and short sterling futures and options
Authors: Sun Peng , Sutcliffe Charles
Published: June 2003

Both the UK spot and futures markets in short‐term interest rates are found to react strongly to
surprises in the scheduled announcements of the repo rate and RPI. Therefore, these announcements should also
affect the market for options on short‐term interest rate futures. Because the repo rate and RPI
announcements are scheduled, the options market can predict the days on which announcement shocks may hit, and
build this information into its volatility expectations. It is argued that the volatility used in pricing
options should alter over time in a predictable nonlinear manner that varies with contract maturity and the
number of forthcoming announcements; but is independent of announcement content. The empirical results
support this hypothesis. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:773–797, 2003
Robust estimation of the optimal hedge ratio
Authors: Harris Richard D. F. , Shen Jian
Published: June 2003

When using derivative instruments such as futures to hedge a portfolio of risky assets, the primary objective
is to estimate the optimal hedge ratio (OHR). When agents have mean‐variance utility and the
futures price follows a martingale, the OHR is equivalent to the minimum variance hedge ratio,which can be
estimated by regressing the spot market return on the futures market return using ordinary least squares. To
accommodate time‐varying volatility in asset returns, estimators based on rolling windows, GARCH, or EWMA
models are commonly employed. However, all of these approaches are based on the sample variance and covariance
estimators of returns, which, while consistent irrespective of the underlying distribution of the data, are not
in general efficient. In particular, when the distribution of the data is leptokurtic, as is commonly found for
short horizon asset returns, these estimators will attach too much weight to extreme observations. This article
proposes an alternative to the standard approach to the estimation of the OHR that is robust to the
leptokurtosis of returns. We use the robust OHR to construct a dynamic hedging strategy for daily returns on the
FTSE100 index using index futures. We estimate the robust OHR using both the rolling window approach and the
EWMA approach, and compare our results to those based on the standard rolling window and EWMA estimators. It is
shown that the robust OHR yields a hedged portfolio variance that is marginally lower than that based on the
standard estimator. Moreover, the variance of the robust OHR is as much as 70% lower than the variance of
the standard OHR, substantially reducing the transaction costs that are associated with dynamic hedging
strategies. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:799–816, 2003
Optimal contract design: For whom?
Authors: Bollen Nicolas P. B. , Smith Tom , Whaley Robert E.
Published: June 2003

In designing a derivative contract, an exchange carefully considers how its attributes affect the expected
profits of its members. On November 3, 1997, the Chicago Mercantile Exchange doubled its tick size of its
S&P 500 futures contract and halved the denomination, providing a rare opportunity to examine empirically
the search for an optimal contract design. This article measures changes in the trading environment that
occurred in the days surrounding the contract redesign. We find a discernible change in the incidence of price
clustering, an increase in the bid/ask spread, a reduction in trading volume, and no meaningful change in
dollar trade size. These results suggest that the contract redesign did not increase accessibility but did
increase market maker revenue. Despite the increase, however, the bid/ask spread of the S&P 500 futures
contract remains low relative to the costs of market making and the spreads in markets for competing
instruments. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:719–750, 2003
Tumor necrosis factor is required for RANTES‐induced astrocyte monocyte chemoattractant protein‐1 production
Authors: Luo Yi , Berman Michael A. , Abromson‐Leeman Sara R. , Dorf Martin E.
Published: June 2003

Astrocytes respond to stimulation with the chemokine RANTES (regulated on activation, normal T cell expressed) by production of a series of cytokines and chemokines, including tumor necrosis factor‐α (TNF‐α) and monocyte chemoattractant protein‐1 (MCP‐1). In the present study we demonstrate that RANTES induces TNF, which in turn stimulates subsequent production of MCP‐1. TNF‐R1 (p55) serves as the principal receptor responsible for MCP‐1 synthesis. The results define an astrocyte proinflammatory cascade that amplifies synthesis of proinflammatory mediators. The implications of these findings to inflammatory diseases of the central nervous system are discussed. © 2003 Wiley‐Liss, Inc.
Constitutive activation of the neuregulin‐1/ErbB receptor signaling pathway is essential for the proliferation of a neoplastic Schwann cell line
Authors: Frohnert Paul W. , Stonecypher Mark S. , Carroll Steven L.
Published: June 2003

Neuregulin‐1 (NRG‐1) proteins promote Schwann cell survival, differentiation and proliferation during development. High levels of an NRG‐like activity are also present in some human peripheral nerve sheath tumors, suggesting that NRG‐1 isoforms may be involved in the development of these neoplasms. We examined the expression of NRG‐1 and its receptors, the erbB membrane tyrosine kinases, in JS1 cells, a rapidly proliferating line derived from a chemically induced rat malignant peripheral nerve sheath tumor (MPNST). Relative to nontransformed Schwann cells, JS1 cells overexpress the NRG‐1 receptor erbB3 and its erbB2 coreceptor; JS1 erbB2 transcripts show no evidence of the activating mutation commonly found in N‐ethyl‐N‐nitrosourea‐induced neoplasms. JS1 cells do not express the epidermal growth factor receptor (EGFR), a kinase implicated in the pathogenesis of a major subset of MPNSTs. JS1 cells also express mRNAs encoding multiple α and β isoforms from the glial growth factor and sensory and motor neuron‐derived factor NRG‐1 subfamilies. Stimulation with NRG‐1β in the presence of forskolin produces a dose‐dependent increase in JS1 DNA synthesis. Even in unstimulated JS1 cells, however, erbB2 and erbB3 are constitutively tyrosine phosphorylated. Reducing this constitutive phosphorylation with the specific erbB inhibitor PD158780 markedly impairs JS1 DNA synthesis. These observations support the hypothesis that NRG‐1 isoforms and erbB kinases act in an autocrine and/or paracrine fashion to promote mitogenesis in JS1 cells. The absence of EGFR expression in JS1 cells suggests that constitutive activation of the NRG‐1/erbB signaling pathway is an alternative means of inducing Schwann cell neoplasia. © 2003 Wiley‐Liss, Inc.
Secreted glycoprotein myocilin is a component of the myelin sheath in peripheral nerves
Authors: Ohlmann Andreas , Goldwich Andreas , Flügel‐Koch Cassandra , Fuchs Anne V. , Schwager Konrad , Tamm Ernst R.
Published: June 2003

The structure of the myelin sheath in peripheral nerves requires the expression of a specific set of proteins. In the present study, we report that myocilin, a member of the olfactomedin protein family, is a component of the myelin sheath in peripheral nerves. Myocilin is a secreted glycoprotein that forms multimers and contains a leucine zipper and an olfactomedin domain. Mutations in myocilin are responsible for some forms of glaucoma, a neurodegenerative disease that is characterized by a continuous loss of optic nerve axons. Myocilin mRNA was detected by Northern blotting in RNA from the rat sciatic and ophthalmic nerves. By one‐ and two‐dimensional gel electrophoresis of proteins from the rat and human sciatic nerves, myocilin was found to migrate at an isoelectric point (pI) of 5.2–5.3 and a molecular weight of 55–57 kDa. Immunohistochemistry showed immunoreactivity for myocilin in paranodal terminal loops of the nodes of Ranvier and outer mesaxons and basal/abaxonal regions of the myelin sheath. Double‐labeling experiments with antibodies against myelin basic protein showed no overlapping, while overlapping immunoreactivity was observed with antibodies against myelin‐associated glycoprotein. The expression of myocilin in the sciatic nerve became detectable at postnatal day (P) 15 and reached adult levels at P20. No or minor expression of myocilin mRNA was found in brain, spinal cord, and optic nerve. mRNA of myocilin was detected in schwannoma cells in situ, but at considerably lower levels than in myelinated nerves. Myocilin might significantly contribute to the structure of the myelin sheath in peripheral nerves. © 2003 Wiley‐Liss, Inc.
T‐cell cytotoxicity of human Schwann cells: TNFα promotes fasL‐mediated apoptosis and IFNγ perforin‐mediated lysis
Authors: Bonetti Bruno , Valdo Paola , Ossi Giovanni , De Toni Luca , Masotto Barbara , Marconi Silvia , Rizzuto Nicolò , Nardelli Ettore , Moretto Giuseppe
Published: June 2003

The ability of resident cells to induce apoptosis of invading immune cells is a major regulatory factor operating in immune‐privileged tissues, including the nervous system. We investigated the cellular and molecular factors participating in modulation of immune response in peripheral nerves, focusing on two cytotoxic pathways: fas ligand (fasL) and perforin. fasL and perforin expression was found by immunochemistry on Schwann cells (Sc) in nerve biopsies from patients with chronic inflammatory demyelinating polyneuritis and on human Sc cultures. Treatment of Sc with tumor necrosis factor (TNF) α and interferon (IFN) γ upregulated the expression of both molecules. In a coculture model, Sc exposed to TNFα or IFNγ were able to induce both apoptotic and lytic injury of T‐lymphocytes. Inactivation of fasL with the neutralizing antibody NOK‐2 abolished T‐cell apoptosis induced by Sc treated with TNFα, but not by Sc treated with IFNγ. Conversely, T‐cell lysis was significantly decreased when IFNγ‐activated Sc were treated with concanamycin A, which inhibited perforin release. At variance with T‐lymphocytes, B‐cells were less sensitive to cytokine‐treated Sc toxicity. Thus, Sc exposed to inflammatory cytokines have the capacity of inducing selective damage of T‐lymphocytes and have the potential of regulating the immune response in the peripheral nervous system. © 2003 Wiley‐Liss, Inc.
Pepstatin A induces extracellular acidification distinct from aspartic protease inhibition in microglial cell lines
Authors: Okada Mitsuko , Irie Shin , Sawada Makoto , Urae Ryuji , Urae Akinori , Iwata Nakao , Ozaki Norio , Akazawa Kohei , Nakanishi Hiroshi
Published: June 2003

The extrusion of protons is considered a very general parameter of the activation of many kinds of membrane or intracellular molecules, such as receptors, ion channels, and enzymes. We found that pepstatin A caused a reproducible, concentration‐related increase in the extracellular acidification rate in two microglial cell lines, Ra2 and 6‐3. Washing abolished pepstatin A‐induced acidification immediately. However, pepstatin A did not cause the extracellular acidification in other cell types, such as CHO, C6 glioma, and NIH3T3 cells. These observations strongly suggest that pepstatin A interacts with certain membrane proteins specific to both Ra2 and 6‐3 cells from outside. N‐methylmaleimide and N,N′‐dicyclohexylcarbodiimide, inhibitors of H+‐ATPase, were found to reduce pepstatin A‐induced response strongly, while bafilomycin A1, a vacuolar H+‐ATPase inhibitor, vanadate, a P‐type H+‐ATPase inhibitor, and NaN3, an F1 ATPase inhibitor, virtually did not. 5‐(N‐ethyl‐N‐isopropyl) amiloride, an inhibitor of Na+/H+ exchanger isoform 1, greatly enhanced pepstatin‐induced response, while amiloride did not. Zn2+, a voltage‐dependent proton channel blocker, did not affect pepstatin‐induced response neither. Staurosporine, a nonspecific inhibitor of protein kinase C, inhibited pepstatin A‐induced response, while chelerythrine, more selective inhibitor of protein kinase C, greatly enhanced it. H‐7 and H‐8 did not affected the response. These findings suggest that pepstatin A induces extracellular acidification in microglia cell lines, Ra2 and 6‐3, through an N‐methylmaleimide‐ and N,N′‐dicyclohexylcarbodiimide‐sensitive, but bafilomycin A1‐insensitive, ATPase, which seems to be distinct from protein kinase C‐dependent process. © 2003 Wiley‐Liss, Inc.
Focal adhesion kinase is required for endothelin‐induced cell cycle progression of cultured astrocytes
Authors: Koyama Yutaka , Yoshioka Yasuhiro , Matsuda Toshio , Baba Akemichi
Published: June 2003

When the brain is damaged, astrocytes often cause hyperplasia resulting in glial scar formation at the injured sites. Endothelins (ETs) have been shown to be involved in the pathophysiologic responses of astrocytes, including proliferation. In this study, we examined the mechanisms underlying the ET‐induced astrocytic G1/S‐phase cell cycle transition by focusing on focal adhesion kinase (FAK). A transient transfection with wild‐type FAK was followed by an increase in bromodeoxyuridine (BrdU) incorporation into cultured rat astrocytes. The increases in BrdU incorporation induced by 100 nM ET‐1 were not found in astrocytes transfected with dominant‐negative FAK mutants (FRNK and dC14‐FAK). The increases in BrdU incorporation induced by 10 nM phorbol 12‐myristate 13‐acetate (PMA) were not affected by the FAK mutants. Wild‐type FAK did not induce stress fiber formation in cultured astrocytes. The dominant negative FAK mutant dC14‐FAK did not prevent ET‐induced astrocytic stress fiber formation. These results suggest that FAK mediated the astrocytic G1/S cell cycle transition induced by ET‐1 downstream of the cytoskeletal actin reorganization. © 2003 Wiley‐Liss, Inc.
Blockade of A2A adenosine receptors prevents basic fibroblast growth factor‐induced reactive astrogliosis in rat striatal primary astrocytes
Authors: Brambilla Roberta , Cottini Lorenzo , Fumagalli Marta , Ceruti Stefania , Abbracchio Maria P.
Published: June 2003

Previous literature data show that blockade of A2A adenosine receptors via selective antagonists induces protection in various models of neurodegenerative diseases. The mechanisms underlying this effect are still largely unknown. Since it is known that excessive reactive astrogliosis is a factor contributing to cell death in diseases characterized by neurodegenerative events, the present study has been aimed at determining whether selective A2A receptor antagonists can counteract the formation of reactive astrocytes induced in vitro by basic fibroblast growth factor (bFGF), a typical trigger of this reaction. Exposure of primary rat striatal astrocytes to the selective A2A antagonist SCH58261 resulted in concentration‐dependent abolition of bFGF induction of astrogliosis in vitro. This effect could also be reproduced with the chemically unrelated A2A antagonist KW‐6002. The direct activation of A2A adenosine receptors by selective receptor agonists was not sufficient per se to induce astrogliosis, suggesting that the A2A receptor needs to act in concert with other bFGF‐induced genes to trigger the formation of reactive astrocytes. These results provide a mechanism at the basis of the neuroprotection induced by A2A receptor antagonists in models of brain damage and highlight this adenosine receptor subtype as a novel target for the pharmacological modulation of the gliotic reaction. © 2003 Wiley‐Liss, Inc.
Protective role of glucose‐6‐phosphate dehydrogenase activity in the metabolic response of C6 rat glioma cells to polyunsaturated fatty acid exposure
Authors: Ramos Karina Lawrence , Colquhoun Alison
Published: June 2003

Polyunsaturated fatty acids (PUFAs) can influence tumor growth and migration, both in vitro and in vivo. The PUFA gamma‐linolenic acid (GLA) has been reported to improve the poor prognosis associated with human gliomas, although its effects at sublethal concentrations on residual cells postsurgery are poorly understood. The study investigated the effects sublethal PUFA doses (90 or 150 μM) may have on rat C6 glioma cell energy metabolism, since an adequate energy supply is essential for cell proliferation, migration, and apoptosis. Of note was the identification of mitochondrial heterogeneity in relation to the mitochondrial membrane potential (MMP), which has been suggested but unproven in previous studies. GLA and eicosapentaenoic acid (EPA) caused significant changes in cellular fatty acid composition and increased the percentage of cells with a low MMP after a 96‐h exposure period. The presence of PUFAs inhibited C6 cell proliferation and migration, although apoptosis was not induced. The protein expression and activity of glucose‐6‐phosphate dehydrogenase was increased after 96‐h incubation with 90 μM GLA and EPA and would allow redox regulation through increased NADPH production, permitting the maintenance of adequate intracellular reduced glutathione concentrations and limiting rates of lipid peroxidation and reactive oxygen species generation. Neither NADP+‐isocitrate dehydrogenase nor NADP+‐malate dehydrogenase activity responded to PUFAs, suggesting it is glucose‐6‐phosphate dehydrogenase that is the principal source of NADPH in C6 cells. These data compliment studies showing that higher concentrations of GLA induced glioma cell death and tumor regression and suggest that GLA treatment could be useful for the inhibition of residual cell proliferation and migration after surgical removal of the tumor mass. © 2003 Wiley‐Liss, Inc.
Emics and Etics of Researching Black Colleges: Applying Facts and Avoiding Fallacies
Authors: Brown M. Christopher
Published: June 2003

This chapter delineates the disparate aspects of internal and external assessments and dispels may common fallacies about historically black colleges and universities.
Studying Community Colleges and Their Students: Context and Research Issues
Authors: Lane Jason E.
Published: June 2003

Diversity of mission, student intent, and student demographics should influence state‐ and institution‐level assessment and evaluation of community colleges.
Diversity Within the Virtual Classroom
Authors: Kinser Kevin
Published: June 2003

The dynamic nature of virtual classrooms presents numerous challenges to assessment and interpretation. This chapter provides an overview of these challenges and sets forth general measures to guide research.
Service Academies of the United States: Issues of Context, Curriculum, and Assessment
Authors: Forest James JF
Published: June 2003

An overview of the U.S. service academies is followed by a discussion of contextual dimensions that provide a useful framework for understanding the success of West Point's recent curricular and assessment initiatives. Some challenges for the service academies in the twenty‐first century are noted, and suggestions are offered for further research on these unique institutions.
Looking Backward to see Ahead: Implications for Research, Policy, and Practice
Authors: Lane Jason E. , Brown M. Christopher
Published: June 2003

This chapter summarizes the unique characteristics of the higher education landscape and provides an overview of concerns and considerations of common interest to institutional researchers at colleges and universities serving diverse populations.
Chemical alteration of tephra in the depositional environment: theoretical stability modelling
Authors: Pollard A. M. , Blockley S. P. E. , Ward K. R.
Published: June 2003

The study of the chemical stability of vitreous material in aqueous media is well‐established. There has to date been little consideration of the implications of variations in the chemical durability of tephra in Quaternary tephrochronology. Chemical alteration can take the form of cationic leaching from the matrix, or complete destruction of the silica network, either of which could constrain the ability to chemically identify distal tephra. Here we apply established models of vitreous durability to the published chemical analyses of a large number of Icelandic tephras in order to predict their relative durabilities under equivalent conditions. This suggests that some important tephras have relatively poor chemical stability, and that rhyolitic tephras are, in general, more stable than basaltic. We conclude that tephras should be expected to show predictable differential chemical stability in the post‐depositional environment. Copyright © 2003 John Wiley & Sons, Ltd.
High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat
Authors: Russell Andrew J. , Tweed Fiona S. , Harris Tim
Published: June 2003

This paper examines the origin and significance of Loch Lomond Stadial (Younger Dryas) gravel deposits at Creag Aoil, Spean Bridge, Scotland. Sedimentation into ice‐dammed lakes in Glen Roy and Glen Spean associated with shorelines at 260 m, 325 m and 350 m is well‐documented, yet little is known about later, lower level lakes near Spean Bridge. Excavations on the northern flanks of the Lundy Channel revealed exposures into a 35–40 m thickness of sand and gravel. These sediments reflect deposition in a subaqueous environment experiencing repeated short‐lived periods of high‐energy subaerial deposition. Deformation structures within subaqueous deposits are associated with at least two ice‐push events. This study presents new evidence for the existence of ice‐dammed lakes at elevations between 260 m and 113 m and for periodic jökulhlaups draining southwest via the Lundy Channel. Active glacier ice associated with the deposits flowed northwest to southeast, driving meltwater across the Great Glen to the Lundy Channel. Glacier retreat was punctuated by periodic minor readvances. Progressive ice retreat was accompanied by ice thinning, and changes in ice‐flow direction and subglacial meltwater routing. These findings add to knowledge of Loch Lomond Stadial deglaciation around Spean Bridge and have implications for our understanding of lacustrine glacier margins during deglaciation. Copyright © 2003 John Wiley & Sons, Ltd.
Time perspectives on glacial landscape formation—glacial flow chronology at Lac aux Goélands, northeastern Québec, Canada
Authors: Clarhäll Anders , Jansson Krister N.
Published: June 2003

We used mapping from aerial photographs and field investigations around Lac Aux Goélands (Whitegull Lake), northeastern Québec, to establish a glacial flow chronology that involves three different glacial landform systems. We interpret the youngest of these systems as related to the late Wisconsinan deglaciation. This system has an up‐glacier discontinuity that marks a temporal shift from warm‐based subglacial conditions to non‐erosive cold‐based subglacial conditions, whereby older glacial landscapes are preserved in the interior of Québec–Labrador. Furthermore, our results support theories suggesting a northward migrating ice divide to a final position south of Ungava Bay during the final deglaciation. The recognition that a glacial landscape is fragmented and consists of smaller, temporally unrelated units is of considerable significance in understanding ice‐sheet dynamics and patterns of subglacial preservation and destruction. This is because a fragmented landscape implies a fragmented formation history, where formation of subglacial landforms occurred in restricted subglacial zones during restricted time periods. Periods of formation must have been separated by periods of preservation and inhibited subglacial reshaping. Based on estimates of the ice margin retreat velocity and the velocity of the warm‐based inward migrating zone, we suggest that periods of preservation were orders of magnitude longer than periods of subglacial landform formation. Copyright © 2003 John Wiley & Sons, Ltd.
Relict rock glaciers as indicators of Mediterranean palaeoclimate during the Last Glacial Maximum (Late Würmian) in northwest Greece
Authors: Hughes P. D. , Gibbard P. L. , Woodward J. C.
Published: June 2003

Relict rock glaciers have been identified and mapped in the high cirques of Mount Tymphi, in the Pindus mountains of northwest Greece. They are periglacial forms and represent the most recent cold‐stage landforms in an area that displays widespread evidence of Pleistocene glaciation. It is likely that these features formed during the Last Glacial Maximum (Late Würmian) as talus rock glaciers, and beneath small cirque glaciers as debris rock glaciers. Comparisons with modern rock glacier–climate relationships suggests mean annual temperatures of ca. 8–9°C lower than present at their time of formation. This temperature reconstruction is in good agreement with recent palaeoclimatic reconstructions for the northern Mediterranean based on a general circulation model. Moreover, as rock glaciers are typical of cold and relatively dry mountain regions, their presence is consistent with palaeobotanical and lake‐level data suggesting a cold and relatively dry climate for the Last Glacial Maximum in Greece. However, the presence of small cirque glaciers above some rock glaciers suggests that although precipitation must have been low enough to preclude glacier extension down to lower altitudes, it was not so low as to inhibit glacier formation entirely. Copyright © 2003 John Wiley & Sons, Ltd.