bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution structure of the cyclic peptide contryphan‐Vn, a Ca2+‐dependent K+ channel modulator
Authors: Eliseo Tommaso , Cicero Daniel Oscar , Romeo Cristina , Schininà Maria Eugenia , Massilia Gabriella Raybaudi , Polticelli Fabio , Ascenzi Paolo , Paci Maurizio
Published: April 2004

The solution structure of contryphan‐Vn, a cyclic peptide with a double cysteine S–S bridge and containing a D‐tryptophan extracted from the venom of the cone snail Conus ventricosus, has been determined by NMR spectroscopy using a variety of homonuclear and heteronuclear NMR methods and restrained molecular dynamics simulations. The main conformational features of backbone contryphan‐Vn are a type IV β‐turn from Gly 1 to Lys 6 and a type I β‐turn from Lys 6 to Cys 9. As already found in other contryphans, one of the two prolines—the Pro4—is mainly in the cis conformation while Pro7 is trans. A small hydrophobic region probably partly shielded from solvent constituted from the close proximity of side chains of Pro7 and Trp8 was observed together with a persistent salt bridge between Asp2 and Lys6, which has been revealed by the diagnostic observation of specific nuclear Overhauser effects. The salt bridge was used as a restraint in the molecular dynamics in vacuum but without inserting explicit electrostatic contribution in the calculations. The backbone of the unique conformational family found of contryphan‐Vn superimposes well with those of contryphan‐Sm and contryphan‐R. This result indicates that the contryphan structural motif represents a robust and conserved molecular scaffold whose main structural determinants are the size of the intercysteine loop and the presence and location in the sequence of the D‐Trp and the two Pro residues. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Synthesis of New Boron‐Rich Building Blocks for Boron Neutron Capture Therapy or Energy‐Filtering Transmission Electron Microscopy
Authors: Raddatz Stefan , Marcello Marco , Kliem Hans‐Christian , Tröster Helmut , Trendelenburg Michael F. , Oeser Thomas , Granzow Christof , Wiessler Manfred
Published: April 2004

The synthesis of a new ortho‐carborane derivative, tetracarboranylketone 4, is reported here. Ketone 4 was prepared from a tetraalkynylated ketone by the addition of decaborane. The keto group was then easily modified to yield the glycosides 17α and 18β, which contain glucose or galactose, respectively, and the nucleotide 13 b. In addition to ketone 4, which is acyclic, cyclic ketone 8 was also synthesised. X‐ray diffraction analysis of compound 4 indicated the presence of two toluene guest molecules per molecule of the host compound. Furthermore, compound 4 displays a rather low cytotoxicity. These novel products can be used as building blocks to create a new class of biomolecules containing high‐density carborane clusters. Such molecules may constitute powerful tools for applications like Boron Neutron Capture Therapy or Energy‐Filtering Transmission Electron Microscopy.
Collective bargaining and community colleges
Authors: Boris Richard J.
Published: April 2004

This chapter reviews the three‐decade history of collective bargaining at community colleges and analyzes how collective bargaining has altered critical areas in the life of community colleges.
Academic freedom and tenure
Authors: Fossey Richard , Wood R. Craig
Published: April 2004

This chapter provides an overview of academic freedom and tenure as applied to the community college.
Copyright issues and technology‐mediated instruction
Authors: Salomon Kenneth D. , Goldstein Michael B.
Published: April 2004

This chapter provides an overview of copyright and intellectual property law as it relates to education in general and telecommunicated instruction in particular.
Preparative resolution of 1‐aminoindan‐1,5‐dicarboxylic acid (AIDA) by chiral ligand‐exchange chromatography
Authors: Natalini Benedetto , Marinozzi Maura , Bade Katrin , Sardella Roccaldo , Thomsen Christian , Pellicciari Roberto
Published: April 2004

Chiral ligand‐exchange chromatography has been shown to be effective in the resolution and semipreparative separation of 1‐aminoindan‐1,5‐dicarboxylic acid (AIDA) enantiomers. In functional activity experiments, only (S)‐AIDA was a potent and mGluR1 subtype selective antagonist. Chirality 16:314–317, 2004. © 2004 Wiley‐Liss, Inc.
Measurement of circular birefringence and circular dichroism of the single crystals of Λ‐(+)589‐ and Δ‐(−)589‐tris(ethylenediamine)cobalt(III) triiodide monohydrate by the extended HAUP method
Authors: Matsuki Ryo , Asahi Toru , Kobayashi Jinzo , Asai Hiroshi
Published: April 2004

We have achieved measuring four optical parameters simultaneously, namely, linear birefringence (LB), circular birefringence (CB), linear dichroism (LD), and circular dichroism (CD), of single crystals of Λ‐(+)589‐ and Δ‐(−)589‐tris(ethylenediamine) cobalt(III) triiodide monohydrate (1) along the <001> plane at the fixed wavelength (514.5 nm). Such measurements are possible only when the High Accuracy Universal Polarimeter (HAUP) is employed; it is called the extended HAUP method. Our experimental results showed that both LB and LD of the Λ‐(+)589‐(1) crystal have the same magnitude as those of the Δ‐(−)589‐(1) crystal. It was also revealed for the first time that the CB data of crystals of Λ‐(+)589‐(1) and Δ‐(−)589‐(1) are almost of the same magnitude, but are of opposite sign, reflecting their opposite absolute configurations. On the other hand, although the CD data obtained for Λ‐(+)589‐(1) is almost three times larger than that for Δ‐(−)589‐(1,) these CD data are also opposite in sign, as expected from the opposite chirality of crystals. Chirality 16:286–293, 2004. © 2004 Wiley‐Liss, Inc.
A parallel Broyden approach to the Toeplitz inverse eigenproblem
Authors: Peinado Jesús , Vidal Antonio M.
Published: April 2004

In this work we show a portable sequential and a portable parallel algorithm for solving the inverse eigenproblem for real symmetric Toeplitz matrices. Both algorithms are based on Broyden's method for solving nonlinear systems. We reduced the computational cost for some problem sizes, and furthermore we managed to reduce spatial cost considerably, compared in both cases with parallel algorithms proposed by other authors and by us, although sometimes quasi‐Newton methods (as Broyden) do not reach convergence in all the test cases. We have implemented the parallel algorithm using the parallel numerical linear algebra library SCALAPACK based on the MPI environment. Experimental results have been obtained using two different architectures: a shared memory multiprocessor, the SGI PowerChallenge, and a cluster of Pentium II PCs connected through a myrinet network. The algorithms obtained are scalable in all the cases. Copyright © 2004 John Wiley & Sons, Ltd.
User transparency: a fully sequential programming model for efficient data parallel image processing
Authors: Seinstra F. J. , Koelma D.
Published: April 2004

Although many image processing applications are ideally suited for parallel implementation, most researchers in imaging do not benefit from high‐performance computing on a daily basis. Essentially, this is due to the fact that no parallelization tools exist that truly match the image processing researcher's frame of reference. As it is unrealistic to expect imaging researchers to become experts in parallel computing, tools must be provided to allow them to develop high‐performance applications in a highly familiar manner. In an attempt to provide such a tool, we have designed a software architecture that allows transparent (i.e. sequential) implementation of data parallel imaging applications for execution on homogeneous distributed memory MIMD‐style multicomputers. This paper presents an extensive overview of the design rationale behind the software architecture, and gives an assessment of the architecture's effectiveness in providing significant performance gains. In particular, we describe the implementation and automatic parallelization of three well‐known example applications that contain many fundamental imaging operations: (1) template matching; (2) multi‐baseline stereo vision; and (3) line detection. Based on experimental results we conclude that our software architecture constitutes a powerful and user‐friendly tool for obtaining high performance in many important image processing research areas. Copyright © 2004 John Wiley & Sons, Ltd.
Genetic screening for individuals at high risk for type 1 diabetes in the general population using HLA Class II alleles as disease markers. A comparison between three European populations with variable rates of disease incidence
Authors: Hermann R. , Bartsocas C. S. , Soltész Gy. , Vazeou A. , Paschou P. , Bozas E. , Malamitsi‐Puchner A. , Simell O. , Knip M. , Ilonen J.
Published: April 2004

Background

To develop screening strategies for identification of individuals at increased genetic risk for type 1 diabetes in three populations with variable disease incidence rates and distinct ethnic origin.

Methods

A stepwise HLA DQB1‐DQA1‐DRB1‐based screening approach was evaluated. Patients with childhood‐onset type 1 diabetes were recruited from Finland (n = 1739), Hungary (n = 149), and Greece (n = 119). Consecutive newborns (2568 from Finland and 1047 from Greece) or healthy schoolchildren (n = 177 from Hungary) served as controls.

Results

The DQB1*02/0302 genotype conferred the highest disease risk in all populations. The DQB1*02/y (y ≠ DQB1*0301,*0302,*0602,*0603, *0604) genotypes were more common and conferred a higher disease risk in the Greek population (OR 4.9) compared to the Finns (OR 1.2). DQB1*0302/x (x ≠ DQB1*02, *0301, *0602, *0603, *0604) genotypes were, in contrast, more prevalent among Finnish cases (32.7%) as compared to Hungarians (18.1%) or Greeks (13.5%). The protective DQB1*0602 or *0603 positive genotypes were most common in the Finns, while DQB1*0301 was more common in Hungarians and Greeks. In all groups, DQA1 and DRB1*04 typing considerably increased the sensitivity of the DQB1‐based screening. The different high‐risk genotype combinations present in about 10% of the background population had a diagnostic sensitivity of 60% in Finland and 80% in Hungary and Greece.

Conclusions

HLA DR‐DQ‐based screening is a feasible tool for the identification of individuals at increased genetic risk for type 1 diabetes in populations with diverse genetic background. The risk markers should, however, be individually selected for the target population since the screening efficiency of various markers is highly dependent on the ethnic group studied. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of Multi‐Nickel‐Substituted Tungstophosphates and Their Stability and Electrocatalytic Properties in Aqueous Media
Authors: Jabbour Darine , Keita Bineta , Mbomekalle Israel‐Martyr , Nadjo Louis , Kortz Ulrich
Published: April 2004

Several sandwich‐type polyoxometallates based on the trivacant [PW9O34]9− fragment with different Ni nuclearities were selected. Their stability and redox behaviour in aqueous media were evaluated by UV/Vis spectroscopy and cyclic voltammetry as a function of pH with the aim of finding the conditions under which these compounds could be suitable candidates for electrocatalytic processes. Two polyoxoanions — [Ni3Na(H2O)2(PW9O34)2]11− and (to a lesser extent) [Ni4Mn2P3W24O94]17− — were found to be stable over a wide pH domain, while [Ni4(H2O)2(PW9O34)2]10− requires the pH to be greater than 4 for its stability. The other derivatives are only suitable for solid‐state studies. The stable polyoxoanions were tested for their activity in the electrocatalytic reduction of nitrate. The results suggest unambiguously that an increase in the number of Ni centres within these sandwich‐type polyanions has a beneficial effect on the electrocatalytic process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Sensitivity of a physically based method for terrain interpolation to initial conditions and its conditioning on stream location
Authors: Grimaldi Salvatore , Teles Vanessa , Bras Rafael L.
Published: April 2004

Production of digital elevation maps often requires interpolation of observations at particular locations. For hydrologic applications the resulting surface should have well deﬁned drainage directions, should reproduce the roughness of natural terrain and should ideally preserve distributions of elevations, slopes and curvatures. The work of J. Niemann et al. (Water Resources Research, 2003, vol. 39, pp. 1017–1032) proposes a physically based interpolation method that is an improvement over commonly used linear or fractal interpolators. The methodology does have difﬁculty dealing with very sparse initial elevation and boundary ﬂux information. This work suggests that using the commonly available horizontal location of main channels (‘blue lines’) improves the physical interpolation signiﬁcantly. The results are illustrated on two river basins. Copyright © 2004 John Wiley & Sons, Ltd.
Performance analysis of multifractal network traffic
Authors: Dinh Dang Trang , Molnár Sándor , Maricza István
Published: April 2004

In this paper we present some new results in the framework of multifractal performance analysis including both the characterization and modeling of multifractal network traffic, and also the multifractal queueing performance analysis. We first propose a new multifractal traffic model for network traffic based on the combination of a multiplicative cascade with an independent lognormal process. This traffic model is able to provide a very accurate fit to the multifractal characteristics of datatraffic including both the scaling function and the moment factor, but it is also simple enough from a practical point of view having only three parameters. In addition, the model features many important properties observed in datatraffic including long‐range dependence (LRD), multifractality and lognormality. We also present an approximation for the queue tail asymptotics in an infinite capacity single server queue serviced at a constant rate driven by a general multifractal input process. We show that in the special and important case of the monofractal fractional Brownian motion (fBm) input traffic our result gives the well‐known Weibullian tail. We prove that the class of Gaussian processes with scaling properties is in the class of monofractal processes and we derive the related characterization functions. Applying the approximation we provide a new practical method for queueing performance estimation of general multifractal traffic. Finally, we present a practical case study to show the practical application of our framework for measured data traffic and also to validate both our multifractal model and our queueing results. Copyright © 2004 AEI
A 2D implicit time‐marching algorithm for shallow water models based on the generalized wave continuity equation
Authors: Dresback Kendra M. , Kolar Randall L. , Dietrich J. Casey
Published: April 2004

This paper builds upon earlier work that developed and evaluated a 1D predictor–corrector time‐marching algorithm for wave equation models and extends it to 2D. Typically, the generalized wave continuity equation (GWCE) utilizes a three time‐level semi‐implicit scheme centred at k, and the momentum equation uses a two time‐level scheme centred at k+12. It has been shown that in highly non‐linear applications, the algorithm becomes unstable at even moderate Courant numbers. This work implements and analyses an implicit treatment of the non‐linear terms through the use of an iterative time‐marching algorithm in the two‐dimensional framework. Stability results show at least an eight‐fold increase in the maximum time step, depending on the domain. Studies also examined the sensitivity of the G parameter (a numerical weighting parameter in the GWCE) with results showing the greatest increase in stability occurs when 1⩽G/τmax⩽10, a range that coincides with the recommended range to minimize errors. Convergence studies indicate an increase in temporal accuracy from first order to second order, while overall error is less than the original algorithm, even at higher time steps. Finally, a parallel implementation of the new algorithm shows that it scales well. Copyright © 2004 John Wiley & Sons, Ltd.
Assessment of two‐equation turbulence modelling for high Reynolds number hydrofoil flows
Authors: Mulvany N. , Tu J. Y. , Chen L. , Anderson B.
Published: April 2004

This paper presents an evaluation of the capability of turbulence models available in the commercial CFD code FLUENT 6.0 for their application to hydrofoil turbulent boundary layer separation flow at high Reynolds numbers. Four widely applied two‐equation RANS turbulence models were assessed through comparison with experimental data at Reynolds numbers of 8.284×106 and 1.657×107. They were the standard k–εmodel, the realizable k–εmodel, the standard k–ωmodel and the shear‐stress‐transport (SST) k–ωmodel. It has found that the realizable k–εturbulence model used with enhanced wall functions and near‐wall modelling techniques, consistently provides superior performance in predicting the flow characteristics around the hydrofoil. Copyright © 2004 John Wiley & Sons, Ltd.
A non‐linear dynamical system approach to finite amplitude Taylor‐Vortex flow of shear‐thinning fluids
Authors: Li Zhenyu , Khayat Roger E.
Published: April 2004

The effect of shear thinning on the stability of the Taylor–Couette flow is explored for a Carreau–Bird fluid in the narrow‐gap limit. The Galerkin projection method is used to derive a low‐order dynamical system from the conservation of mass and momentum equations. In comparison with the Newtonian system, the present equations include additional non‐linear coupling in the velocity components through the viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of the circular Couette flow, becomes lower as the shear‐thinning effect increases. That is, shear thinning tends to precipitate the onset of Taylor vortex flow, which coincides with the onset of a supercritical bifurcation. Comparison with existing measurements of the effect of shear thinning on the critical Taylor and wave numbers show good agreement. The Taylor vortex cellular structure loses its stability in turn, as the Taylor number reaches a critical value. At this point, an inverse Hopf bifurcation emerges. In contrast to Newtonian flow, the bifurcation diagrams exhibit a turning point that sharpens with shear‐thinning effect. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of γ‐irradiation on the biophysical and morphological properties of corn
Authors: Al‐Salhi Mohammed , Ghannam Magdi M. , Al‐Ayed Mohammed S. , El‐Kameesy Samir U. , Roshdy Shahira
Published: April 2004

The effects of γ‐irradiation on the biophysical and morphological properties of corn plants were investigated. The irradiation doses were 0, 1, 1.5, 2.5, 5, and 10 krad. Corn grains exposed to 1.5 and 2.5 krad showed highly significant changes in all growth parameters. Fluorescence and light absorption spectra of chlorophyll attributed to different doses treatments of corn grains clearly confirmed the superiority of 1.5 krad irradiation dose in stimulating corn plants. Furthermore, the frequency dependence of the relative permittivity and the electric conductivity of the treated samples have been performed and discussed. The obtained results give another support via the biophysical properties for the 1.5 krad irradiation dose to be the most favorable one to improve the plant growth characteristics.
Spontaneous ectopic recombination in cell‐type‐specific Cre mice removes loxP‐flanked marker cassettes in vivo
Authors: Eckardt Dominik , Theis Martin , Döring Britta , Speidel Dina , Willecke Klaus , Ott Thomas
Published: April 2004

Conditional gene targeting using the Cre/loxP technology generally includes integration of a selection marker cassette flanked by loxP recognition sites (floxed) in the target gene locus. Subsequent marker removal avoids possible impairment of gene expression or mosaicism due to partial and total deletions after Cre‐mediated recombination in vivo. The use of deleter Cre mice for in vivo marker removal in floxed connexin43 mice revealed considerable mosaicism, but no selective marker removal. In addition, we noted that several Cre transgenic lines displayed spontaneous ectopic activity, reminiscent of deleter Cre mice, and required the confirmation of cell type‐specific deletion in every individual mouse. When we used myosin heavy chain promoter Cre (αMyHC‐Cre) mice for cardiomyocyte specific deletion, we observed, in addition to cardiomyocyte‐restricted or complete excision, selective marker removal in a subgroup of mice as well. Thus, selective marker removal can be achieved as a byproduct of cell‐type restricted deletion. genesis 38:159–165, 2004. © 2004 Wiley‐Liss, Inc.
Xenopus embryonic poly(A) binding protein 2 (ePABP2) defines a new family of cytoplasmic poly(A) binding proteins expressed during the early stages of vertebrate development
Authors: Good Peter J. , Abler Lisa , Herring Dina , Sheets Michael D.
Published: April 2004

We describe a new RNA binding protein from Xenopus we have named ePABP2 (embryonic poly(A) binding protein type II). Based on amino acid similarity, ePABP2 is closely related to the ubiquitously expressed nuclear PABP2 protein that directs the elongation of mRNA poly(A) tails during pre‐mRNA processing. However, in contrast to known PABP2 proteins, Xenopus ePABP2 is a cytoplasmic protein that is predominantly expressed during the early stages of Xenopus development and in adult ovarian tissue. Biochemical experiments indicate ePABP2 binds poly(A) with specificity and that this binding requires the RRM domain. Mouse and human ePABP2 proteins were also identified and mouse ePABP2 expression is also confined to the earliest stages of mouse development and adult ovarian tissue. We propose that Xenopus ePABP2 is the founding member of a new class of poly(A) binding proteins expressed in vertebrate embryos. Possible roles for this protein in regulating mRNA function in early vertebrate development are discussed. genesis 38:166–175, 2004. © 2004 Wiley‐Liss, Inc.
Senseless is required for pupal retinal development in Drosophila
Authors: Frankfort Benjamin J. , Pepple Kathryn L. , Mamlouk Mark , Rose Matthew F. , Mardon Graeme
Published: April 2004

Summary: Drosophila sensory organs are specified by a family of proneural genes which induce the expression of several common targets. One such target is senseless, which encodes a zinc finger transcription factor. We analyzed the function of senseless during pupal retinal development and found that senseless is required for recruitment of both cone and pigment cells, the pupal‐derived ommatidial support cells. We also found that Senseless is expressed in neural precursors shortly after the larval–pupal transition and is both necessary and sufficient for interommatidial bristle development. Furthermore, senseless is the primary target of achaete and scute during interommatidial bristle development. We also identified several differences between the development of interommatidial bristles and other macrochaete. In particular, EGFR signaling is not required for interommatidial bristle development, nor is positive feedback regulation of proneural genes by senseless. A model for interommatidial bristle specification is presented. genesis 38:182–194, 2004. © 2004 Wiley‐Liss, Inc.
Transition nuclear proteins are required for normal chromatin condensation and functional sperm development
Authors: Zhao Ming , Shirley Cynthia R. , Hayashi Shotaro , Marcon Ludovic , Mohapatra Bhagyalaxmi , Suganuma Ryota , Behringer Richard R. , Boissonneault Guylain , Yanagimachi Ryuzo , Meistrich Marvin L.
Published: April 2004

Summary: The histone‐to‐protamine transition is important in the formation of spermatozoa. In mammals this involves two steps: replacement of histones by transition nuclear proteins (TPs) and replacement of TPs by protamines. To determine the functions of the TPs and their importance for sperm development, we generated mice lacking both TPs, since mice lacking only TP1 or TP2 were fertile. Our results indicated that TP1 and TP2 had partially complemented each other. In mice lacking both TPs, nuclear shaping, transcriptional repression, histone displacement, and protamine deposition proceeded relatively normally, but chromatin condensation was irregular in all spermatids, many late spermatids showed DNA breaks, and protamine 2 was not posttranslationally processed. Nevertheless, genomic integrity was maintained in mature spermatids, since efficient fertilization and production of offspring were achieved by intracytoplasmic sperm injection. However, many mature spermatids were retained in the testis, epididymal spermatozoa were drastically reduced in number and were highly abnormal, and the mice were sterile. Most epididymal spermatozoa were incapable of fertilization even using intracytoplasmic sperm injection. Thus, in mammals TPs are required for normal chromatin condensation, for reducing the number of DNA breaks, and for preventing the formation of secondary defects in spermatozoa, eventual loss of genomic integrity, and sterility. genesis 38:200–213, 2004. © 2004 Wiley‐Liss, Inc.
Consolidation of CS and US representations in associative fear conditioning
Authors: Frankland Paul W. , Josselyn Sheena A. , Anagnostaras Stephan G. , Kogan Jeffrey H. , Takahashi Eiki , Silva Alcino J.
Published: April 2004

Much attention has been paid to the associative processes that are necessary to fuse together representations of the various components of an episodic memory. In the present study, we focus on the processes involved in the formation of lasting representations of the individual components that make up a fear‐conditioning episode. In one‐trial contextual fear conditioning experiments, weak conditioning to context occurs if the shock is delivered immediately following placement of the animal in a novel conditioning apparatus, a phenomenon known as the immediate shock deficit. We show that the immediate shock deficit in mice may be alleviated by pre‐exposure to either the context or shock. In using this approach to temporally dissect a contextual fear‐conditioning task into its constituent representational and associative processes, we are able to examine directly the processes that are important for formation of lasting representations of the context conditioned stimulus (CS) or unconditioned stimulus (US). Our data indicate that the formation of a lasting representation of the context or shock engages protein synthesis‐dependent processes. Furthermore, genetic disruption of cAMP‐responsive element binding protein (CREB), a transcription factor that regulates the synthesis of new proteins required for long‐term memory, disrupts the formation of lasting context memories. We go on to show that the stress hormone epinephrine modulates the consolidation of a context memory, and reverses consolidation deficits in the CREB‐deficient mice. Finally we show that disrupting either NMDA or calcium/calmodulin‐dependent kinase II (CaMKII) function impairs consolidation of context memories. Together, these data suggest that this approach is particularly suited for the characterization of molecular and cellular processes underlying the formation of stimulus representations. © 2004 Wiley‐Liss, Inc.
Overexpression of calbindin D28k in dentate gyrus granule cells alters mossy fiber presynaptic function and impairs hippocampal‐dependent memory
Authors: Dumas T.C. , Powers E.C. , Tarapore P.E. , Sapolsky R.M.
Published: April 2004

Calcium is a key signaling ion for induction of synaptic plasticity processes that are believed to influence cognition. Mechanisms regulating activity‐induced increases in neuronal calcium and related synaptic modifications are not fully understood. Moreover, involvement of specific synapses in discrete aspects of spatial learning remains to be elucidated. We used herpes simplex amplicons to overexpress calbindin D28k (CaBP) selectively in dentate gyrus (DG) granule cells. We then examined the effects on hippocampal network activity by recording evoked synaptic responses in vivo and in vitro and analyzing hippocampal‐dependent behavior. Relative to Lac‐Z‐ and sham‐infected controls, CaBP overexpression increased mossy fiber (MF‐CA3) excitatory postsynaptic potentials and reduced paired‐pulse facilitation (PPF), suggesting an increase in presynaptic strength. Additionally, CaBP overexpression reduced long‐term potentiation (LTP), caused a frequency‐dependent inhibition of post‐tetanic potentiation (PTP), and impaired spatial navigation. Thus, increasing CaBP levels selectively in the DG disrupts MF‐CA3 presynaptic function and impairs spatial cognition. The results demonstrate the power of gene delivery in the study of the neural substrates of learning and memory and suggest that mossy fiber synaptic plasticity is critical for long‐term spatial memory. © 2004 Wiley‐Liss, Inc.
Radiation data corrections for snow‐covered sensors: are they needed for snowmelt modelling?
Authors: Melloh Rae A. , Hall Tommie J. , Bailey Ronald
Published: April 2004

Up‐looking solar and atmospheric radiation sensors at remote and quasi‐remote weather stations are typically intermittently covered by snow in the winter. Numerous years of radiation data compromised in this way have been collected and archived at the Snow Research Station (SRS) in Danville, Vermont, and undoubtedly at numerous other research stations around the globe. Potential users of these archived data must question whether the data have value for their purpose, whether they can be corrected, what methods can be used to correct them, and perhaps most importantly, will time‐consuming correction efforts be justified by improved model performance. To answer these questions, both simple and elaborate methods of correcting incident solar and atmospheric radiation data were developed and applied to the 2001 snow season radiation data collected at the SRS. Snow‐affected incident solar radiation was estimated with reflected solar radiation measurements and either a simple albedo assumption or an albedo model. The equations of Idso, Brutsaert, Brunt, and Anderson and Baker were considered for correcting atmospheric radiation. The technique of Anderson and Baker was a good practical choice for this site, when used with a station offset, clearness index, and clear‐sky radiation model. Energy balance snowmelt calculations were made with SNTHERM, an internationally known and publicly available physically based snow process model. There was little justification for more than minimal corrections to radiation measurements for the presence of snow on radiation sensors when modelling snow depth, water equivalent, or melt efflux, because errors caused by snow‐covered solar and atmospheric radiation sensors largely offset one another. More elaborate efforts to correct both solar and atmospheric radiation data would be justified when correct quantification of individual snowpack energy components is important. Copyright © 2004 John Wiley & Sons, Ltd.
Prospective study of three major dietary patterns and risk of gastric cancer in Japan
Authors: Kim Mi Kyung , Sasaki Satoshi , Sasazuki Shizuka , Tsugane Shoichiro
Published: April 2004

Dietary pattern analysis is an alternative and complementary approach to identify the relationship between diet and the risk of chronic disease. This study was aimed at investigating the associations between dietary patterns and the risk of gastric cancer in Japan. Using baseline data from a prospective study of 20,300 men and 21,812 women, we conducted factor analysis and identified 3 major dietary patterns, healthy, traditional and Western, and calculated the factor scores of each pattern for individuals. During 10 years of follow‐up, 400 cases of gastric cancer were identified. We found an inverse association between the healthy pattern and gastric cancer risk in women [rate ratio for highest quartile (RR) = 0.56; 95% CI = 0.32–0.96; p for trend = 0.03], but not in men. In contrast, the traditional pattern was significantly associated with the increased risk of gastric cancer in both genders (for men, RR = 2.88, 95% CI = 1.76–4.72; for women, RR = 2.40, 95% CI = 1.32–4.35). The Western pattern was not associated with risk. These associations persisted in histologic subtypes. Our findings support the idea that the healthy pattern decreased the risk of gastric cancer among females, while the traditional pattern increased the risk in both genders. © 2004 Wiley‐Liss, Inc.
Distance, trade and FDI: a Hausman–Taylor SUR approach
Authors: Egger Peter , Pfaffermayr Michael
Published: April 2004

This paper analyses the effects of distance as a common determinant of exports and FDI in a three‐factor New Trade Theory model, assuming that distance affects both pure trade costs and plant set‐up costs. Exports and FDI are not necessarily substitutes with respect to distance, since the predicted impact depends on its importance for fixed plant set‐up costs relative to transportation costs and on the relative importance of vertical MNEs. For the empirical specification, we suggest that the impact of time‐invariant variables such as distance is most appropriately analysed in a Hausman–Taylor SUR model. We apply our model to industry‐level data of bilateral outward FDI stocks and exports of the US and Germany. Copyright © 2004 John Wiley & Sons, Ltd.
More powerful panel data unit root tests with an application to mean reversion in real exchange rates
Authors: Smith L. Vanessa , Leybourne Stephen , Kim Tae‐Hwan , Newbold Paul
Published: April 2004

Unit root tests, seeking mean or trend reversion, are frequently applied to panel data. We show that more powerful variants of commonly applied tests are readily available. Moreover, power gains persist when the modifications are applied to bootstrap procedures that may be employed when cross‐correlation of a rather general sort among individual panel members is suspected. Copyright © 2004 John Wiley & Sons, Ltd.
Sequence‐specific potentiation of topoisomerase II inhibitors by the histone deacetylase inhibitor suberoylanilide hydroxamic acid
Authors: Marchion Douglas C. , Bicaku Elona , Daud Adil I. , Richon Victoria , Sullivan Daniel M. , Munster Pamela N.
Published: April 2004

Acetylation of histones leads to conformational changes of DNA. We have previously shown that the histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA), induced cell cycle arrest, differentiation, and apoptosis. In addition to their antitumor effects as single agents, HDAC inhibitors may cause conformational changes in the chromatin, rendering the DNA more vulnerable to DNA damaging agents. We examined the effects of SAHA on cell death induced by topo II inhibitors in breast cancer cell lines. Topo II inhibitors stabilize the topo II–DNA complex, resulting in DNA damage. Treatment of cells with SAHA promoted chromatin decondensation associated with increased nuclear concentration and DNA binding of the topo II inhibitor and subsequent potentiation of DNA damage. While SAHA‐induced histone hyperacetylation occurred as early as 4 h, chromatin decondensation was most profound at 48 h. SAHA‐induced potentiation of topo II inhibitors was sequence‐specific. Pre‐exposure of cells to SAHA for 48 h was synergistic, whereas shorter pre‐exposure periods abrogated synergy and exposure of cells to SAHA after the topo II inhibitor resulted in antagonistic effects. Synergy was not observed in cells with depleted topo II levels. These effects were not limited to specific types of topo II inhibitors. We propose that SAHA significantly potentiates the DNA damage induced by topo II inhibitors; however, synergy is dependent on the sequence of drug administration and the expression of the target. These findings may impact the clinical development of combining HDAC inhibitors with DNA damaging agents. © 2004 Wiley‐Liss, Inc.
Retinoic acid regulates the expression of PBX1, PBX2, and PBX3 in P19 cells both transcriptionally and post‐translationally
Authors: Qin Pu , Haberbusch Juliet M. , Soprano Kenneth J. , Soprano Dianne Robert
Published: April 2004

Pre‐B cell leukemia transcription factors (PBXs) are important co‐factors for the transcriptional regulation mediated by a number of Hox proteins during embryonic development. It was previously shown that the expression of several Pbx genes is elevated in mouse embryo limb buds and embryonal carcinoma P19 cells upon retinoic acid (RA) treatment although the mechanism of this induction is not well understood. In this report, we demonstrate that PBX1a, PBX1b, PBX2, and PBX3 mRNAs and PBX1/2/3 proteins are induced during endodermal and neuronal differentiation of P19 cells in a RAR‐dependent subtype‐unspecific manner following RA treatment. The increases in both PBX1 mRNA and PBX3 mRNA levels are secondary responses to RA treatment requiring new proteins synthesis while the increase in PBX2 mRNA is a primary response. The RA‐dependent increases in PBX1 mRNA, PBX2 mRNA, and PBX3 mRNA levels are likely to be transcriptionally regulated since the stability of these mRNAs does not change. In addition, the half‐lives of PBX1/2/3 proteins are significantly extended by RA treatment. Two possible mechanisms could contribute to the stabilization of PBX proteins: PBX proteins associate with RA‐dependent increased levels of MEIS proteins, and RA may decrease the proteasome dependent degradation of PBX proteins. © 2004 Wiley‐Liss, Inc.
Inactivated tumor suppressor Rb by nitric oxide promotes mitosis in human breast cancer cells
Authors: Radisavljevic Ziv
Published: April 2004

Inactivation of tumor suppressor protein retinoblastoma (Rb) is important mechanism for the G1/S transition during cell cycle progression. Human breast cancer cells T47D release great amount of nitric oxide (NO), but its relation to tumor suppressor Rb is unknown. In this study, it is shown that NO induces phosphorylation and inactivation of Rb tumor suppressor protein, increasing G2/M phase and cell proliferation of breast cancer cells T47D. NO did not induce changes in p53 ser‐15 phosphorylation, the most phosphorylated site of p53 during its activation. These data indicate that NO induces cell proliferation through the Rb pathway. NO phosphorylates and inactivates tumor suppressor protein Rb inducing mitosis by the p53 independent pathway in breast cancer cell. © 2004 Wiley‐Liss, Inc.
Civic responsibility among Australian adolescents: Testing two competing models
Authors: Silva Lisa da , Sanson Ann , Smart Diana , Toumbourou John
Published: April 2004

The development of civic responsibility is considered to be an important component of healthy adolescent development. However, the study of its development has been relatively neglected and few studies have attempted to ground understanding of its development in a theoretical framework. The present study operationalized civic responsibility as attitudes and behaviors relating to political and community issues that are beneficial to society and compared two theoretical causal models, the social development model (SDM) and a coping‐competency model for their predictive value. Gender differences were also assessed. A total of 500 subjects, drawn from a longitudinal study (the Australian Temperament Project), participated in the study, using questionnaire and interview data. Approximately 1 in 5 adolescents actively engaged in behaviors reflecting community civic responsibility and less than 1 in 10 actively participated in the political arena. However, positive levels of social awareness were evident. Hierarchical multiple regression analyses indicated that the SDM had the most predictive value for political and community civic responsibility. Peer encouragement and peer participation were the most significant predictors. Variables from the coping‐competency model played some role in the prediction of community, but not political, civic responsibility. Gender differences in community civic responsibility, but not political civic responsibility, were found. One in two adolescents indicated that they would participate in volunteer work or political activities if more opportunities existed. This suggests the need for greater availability of appropriate community‐oriented activities for adolescents. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 229–255, 2004.
The impact of community health workers on the self‐determination, self‐sufficiency, and decision‐making ability of low‐income women and mothers of young children
Authors: Kovach Andrea Crivelli , Becker Julie , Worley Heidi
Published: April 2004

Pregnant women at high risk for adverse health outcomes can benefit from the services of community health workers. Maternity Care Coalition identifies at risk women and provides links to health care and social services through the MOMobile Program. The purpose of this study was to explore (a) the relationship formed between community health workers and pregnant women, and (b) the change over time in a mother's perceived level of empowerment as measured by self‐sufficiency, self‐determination, and decision‐making skills. A multiphase study was developed to collect data. Focus group interviews with community health workers explored their professional role, their relationship with mothers, and the meaning of decision‐making, self‐sufficiency, and self‐determination as empowerment constructs. A questionnaire was developed to measure each construct at two points in time. A pilot study with 80 women was conducted. Scores for each construct and overall empowerment were calculated and the pre‐ and post‐scores compared to measure change over time. Results of paired t‐tests showed significant differences between the postpartum mean score for decision‐making (P < .01), self‐sufficiency (P < .01), self‐determination (P < .001), and overall empowerment (P < .001) and the mean scores on each construct at registration. Results suggest that empowerment can be operationalized in community settings and that increasing an at risk pregnant woman's sense of empowerment may positively impact the overall health of the mother and child. Further research is needed to assess the full impact of this variable as a health status indicator. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 343–356, 2004.
Angiopoietin‐2 enhances retinal vessel sensitivity to vascular endothelial growth factor
Authors: Oshima Yuji , Deering Tye , Oshima Sachiko , Nambu Hiroyuki , Reddy P. Seshidhar , Kaleko Michael , Connelly Sheila , Hackett Sean F. , Campochiaro Peter A.
Published: April 2004

Increased expression of vascular endothelial growth factor (VEGF) in the retina starting after postnatal day (P)7 results in neovascularization originating from deep retinal capillaries, but not those in the superficial capillary bed. Doxycycline was administered starting P0 to double transgenic mice with inducible expression of VEGF in the retina. These mice showed proliferation and dilation of superficial retinal capillaries, indicating that at this stage of development, the superficial capillaries are sensitive to the effects of VEGF. Angiopoietin‐2 (Ang2) is expressed along the surface of the retina for several days after birth, but by P7 and later, Ang2 is only expressed in the region of the deep capillary bed. In mice with ubiquitous doxycycline‐inducible expression of Ang2, in the absence of doxycycline, intravitreous injection of a gutless adenoviral vector expressing VEGF (AGV.VEGF) resulted in neovascularization of the cornea and iris, but no retinal neovascularization. After treatment with doxycycline to induce Ang2 expression, intravitreous injection of AGV.VEGF caused retinal neovascularization in addition to corneal and iris neovascularization. The retinal neovascularization originated from both the superficial and deep capillary beds. These data suggest that Ang2 promotes sensitivity to the angiogenic effects of VEGF in retinal vessels. © 2004 Wiley‐Liss, Inc.
Na+/Mg2+ exchange is functionally coupled to the insulin receptor
Authors: Ferreira Ana , Rivera Alicia , Romero José R.
Published: April 2004

Regulation of cellular Mg2+ levels by insulin has been shown in various tissues. However, the mechanisms for hormonal regulation of cellular Mg2+ have not been well described. We studied the effect of insulin on Na+/Mg2+ exchange in normal human cells, measuring Na+/Mg2+ exchange activity as net total Mg2+ efflux driven by an inward Na+ gradient in Mg2+‐loaded red blood cells (RBCs). Na+/Mg2+ exchange was increased significantly by the addition of 2.4 nmol/L of insulin to the flux medium (from 0.60 ± 0.06 mmol/L cell × h to 0.75 ± 0.08 mmol/L cell × h [P = 0.0098, n = 44]). A dose‐response curve for the effects of insulin on the exchanger activity gave an estimated EC50 for insulin of 0.95 ± 0.31 nmol/L and a Vmax of 0.86 ± 0.12 mmol/L cell × h (n = 7). Kinetics of the Na+/Mg2+ exchange were characterized by measuring its activity as a function of Mg2+ and Na+ concentrations. The K0.5 for cellular Mg2+ was not affected by incubation with insulin. However, the K0.5 for extracellular Na+ decreased from 69.9 ± 6.3 to 40.3 ± 8.4 mol/L (n = 5, P = 0.03) in the presence of insulin. We also studied the effect of wortmannin (WT), a PI 3‐kinase inhibitor, on activity of the exchanger. WT significantly blocked the insulin‐stimulated Na+/Mg2+ activity (n = 6, P = 0.048), with an IC50 of 0.5 nmol/L. LY294002, another PI 3‐kinase inhibitor, likewise blocked the insulin‐stimulated activity of the exchanger. Therefore, insulin regulates cellular Mg2+ metabolism in part via an increase in the affinity for Na+ of the Na+/Mg2+ exchange and PI 3‐kinase activation, suggesting another role for the PI 3‐kinase pathway in insulin‐mediated cellular events. © 2003 Wiley‐Liss, Inc.
Inducible expression of a MAP kinase phosphatase‐3‐GFP chimera specifically blunts fibroblast growth and ras‐dependent tumor formation in nude mice
Authors: Marchetti S. , Gimond C. , Roux D. , Gothié E. , Pouysségur J. , Pagès Gilles
Published: April 2004

The p42/p44 mitogen activated protein kinase (MAPK) pathway participates in a wide range of cellular programs including proliferation, migration, differentiation, and survival. Specific pharmacological inhibitors, like PD98059 and U0126, are often used to inhibit p42/p44 MAPK signaling. However, these inhibitors are not appropriate to study the function of these kinases in whole organisms. We thus developed an inducible system designed to inhibit p42/p44 MAPK activity through the expression of a phosphatase specific for these two kinases, the MAPK phosphatase 3 (MKP‐3). A fibroblast cell line was established in which MKP‐3 expression is controlled by tetracycline. Tetracycline‐induced MKP‐3 resulted in partial de‐phosphorylation of p42/p44 MAPKs in serum‐stimulated cells. However, we could improve MKP‐3 stability and thereby the rate of MAPK de‐phosphorylation, when the C‐terminal end of MKP‐3 was fused to the green fluorescent protein (GFP). Importantly, the fusion of GFP to MKP‐3 did not alter the specificity of the phosphatase towards its MAPK substrates. We further show that conditional expression of MKP‐3‐GFP in this fibroblast cell line results in the inhibition of: (a) the phosphorylation of the p42/p44 MAPK substrates Elk1 and HIF‐1α, (b) vascular endothelial growth factor (VEGF), cyclin D1, and c‐fos gene transcription in response to MAPK pathway activation, and (c) cell proliferation. Finally, the MKP‐3‐GFP inducible cell line was transformed by Ha‐ras and injected into nude mice. Treatment of mice with the tetracycline analog doxycycline resulted in a large delay in tumor emergence and growth as compared to the untreated control group, indicating that MKP‐3‐GFP activity is maintained in vivo. Altogether, these results show that inducible expression of MKP‐3‐GFP constitutes a valuable tool to study the role of p42/p44 MAPKs in various cellular responses in both cultured cell and animal models, a tool that may also be used to block unwanted cell growth in pathological conditions. © 2004 Wiley‐Liss, Inc.