bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroprotective effect of adenine on purkinje cell survival in rat cerebellar primary cultures
Authors: Watanabe Shun , Yoshimi Yoji , Ikekita Masahiko
Published: November 2003

Although adenosine or ATP is known to control various physiological functions in the brain, including synaptic transmission, neuronal cell death, and neurite outgrowth via P1 or P2 purinergic receptors in the nervous system, little is known about the functions of many other purine derivatives. We examined the effects of various purines on survival in the cerebellar cortex of Purkinje cells with large cell bodies and highly branched dendrites, and it was found that some purine and pyrimidine derivatives influence Purkinje cell survival. Treatment with adenine, guanine, guanosine, guanine nucleotides, and uracil nucleotides protected Purkinje cells from cell death in the cerebellar primary cultures. Among the effective compounds, adenine had the most potent survival activities on Purkinje cells. Other adenine‐based purines such as adenosine, AMP, ADP, and ATP did not promote Purkinje cell survival. Furthermore, metabolic inhibitors of adenine had no effect on the protective ability of adenine for Purkinje cells, suggesting that adenine itself, not adenine metabolites, maintains Purkinje cell survival. These results suggest that adenine is involved in the control of Purkinje cell survival in cerebellar primary cultures via a novel adenine‐dependent mechanism. © 2003 Wiley‐Liss, Inc.
Effect of excess extracellular glutamate on dendrite growth from cerebral cortical neurons at 3 days in vitro: Involvement of NMDA receptors
Authors: Monnerie Hubert , Shashidhara Shalini , Le Roux Peter D.
Published: November 2003

Glutamate is an important regulator of dendrite development; however, during cerebral ischemia, massive glutamate release can lead to neurodegeneration and death. An early consequence of glutamate excitotoxicity is dendrite injury, which often precedes cell death. We examined the effect of glutamate on dendrite growth from embryonic day 18 (E18) mouse cortical neurons grown for 3 days in vitro (DIV) and immunolabeled with anti‐microtubule‐associated protein (MAP)2 and anti‐neurofilament (NF)‐H, to identify dendrites and axons, respectively. Cortical neurons exposed to excess extracellular glutamate (100 μM) displayed reduced dendrite growth, which occurred in the absence of cell death. This effect was mimicked by the ionotropic glutamate receptor agonist N‐methyl‐D‐aspartate (NMDA) and blocked by the ionotropic glutamate receptor antagonist kynurenic acid and the NMDA receptor‐specific antagonist MK‐801. The non‐NMDA receptor agonist AMPA, however, did not affect process growth. Neither NMDA nor AMPA influenced neuron survival. Immunolabeling and Western blot analysis of NMDA receptors using antibodies against the NR1 subunit, demonstrated that immature cortical neurons used in this study, express NMDA receptors. These results suggest that excess glutamate decreases dendrite growth through a mechanism resulting from NMDA receptor subclass activation. Furthermore, these data support the possibility that excess glutamate activation of NMDA receptors mediate both cell death in mature neurons and the inhibitory effect of excess glutamate on dendrite growth in immature neurons or in the absence of cell death. © 2003 Wiley‐Liss, Inc.
GeneChip analysis of hippocampal gene expression profiles of short‐ and long‐attack‐latency mice: Technical and biological implications
Authors: Feldker Dorine E.M. , Datson Nicole A. , Veenema Alexa H. , Proutski Vitali , Lathouwers Desiree , de Kloet E. Ron , Vreugdenhil Erno
Published: November 2003

To gain insight into the molecular mechanisms underlying the behavioral differences between two mouse lines genetically selected for long and short attack latency (LAL and SAL mice, respectively), we have recently applied the large‐scale gene expression profiling method known as serial analysis of gene expression (SAGE) to generate hippocampal gene expression profiles of these mice. The aim of the present study is to extend and validate the SAGE expression profile of hippocampi of LAL and SAL mice using GeneChips (Affymetrix, Santa Clara, CA; one array per mouse, n = 5 per mouse line). As was the case with SAGE, GeneChips detect only medium‐ to high‐abundance genes in the hippocampus. Extensive analysis of GeneChip data using very stringent parameters shows differential expression of 122 genes, all except one of which were expressed at higher levels in LAL mice (P < 0.01). As predicted by SAGE, our data indicate higher expression of several cytoskeleton genes in LAL mice, suggesting longer axonal and dendritic projections in the hippocampus of these mice. This is consistent with our tentative model, in which the behavioral differences between LAL and SAL mice may be related to structural differences in the hippocampus. In addition, a group of 76 genes with diverse biological function and 46 expressed sequence tags (ESTs) were all expressed at higher levels in LAL mice. A novel finding in this study was the significantly lower expression of only a single gene, growth arrest‐specific gene (gas5), in LAL mice. As gas5 does not encode a protein but several small nuclear RNAs, our data suggest that small RNAs may contribute to the molecular mechanisms underlying the extreme behavioral differences between LAL and SAL mice. © 2003 Wiley‐Liss, Inc.
Adenoviral‐mediated expression of functional na+ channel β1 subunits tagged with a yellow fluorescent protein
Authors: Fry Mark , Porter Donna M. , Maue Robert A.
Published: November 2003

Voltage‐gated sodium (Na+) channels typically contain a pore‐forming α subunit and one or two auxiliary β subunits. Although initial characterization of known α and β subunits has been facilitated by expression in heterologous cells, to understand fully the differences between individual subunits and the functional consequences of selective subunit expression, there is a need to acutely manipulate expression in cells that endogenously express Na+ channels. To this end, we have constructed a recombinant adenovirus containing a cDNA for a mouse Na+ channel β1 subunit with a yellow fluorescent protein fused to its C‐terminus (Ad‐β1‐EYFP), and with fluorescence microscopy detected β1‐EYFP expression in primary cerebellar neurons and Chinese hamster ovary (CHO) cells upon transduction with this adenovirus, including expression in the plasma membrane. Consistent with this, patch clamp recordings confirmed that Na+ currents in CHO cells expressing mouse Nav1.4 α subunits were appropriately modified by the viral‐mediated expression of β1‐EYFP subunits. The results demonstrate that adenoviral‐mediated gene delivery can be used effectively to express epitope‐tagged Na+ channel subunits with properties similar to wild‐type subunits, and suggest that Ad‐β1‐EYFP will be a useful reagent for investigating Na+ channels in a variety of excitable cell types, including neurons. © 2003 Wiley‐Liss, Inc.
Loss of pro‐apoptotic BH3‐only Bcl‐2 family member bim does not protect mutant Lurcher mice from neurodegeneration
Authors: Bouillet Philippe , Robati Mikara , Adams Jerry M. , Strasser Andreas
Published: November 2003

Lurcher (lc) mice have a semi‐dominant mutation in the gene encoding the δ2 glutamate receptor (GRID2). The resulting constitutive activity of this receptor in heterozygous +/lc (grid+/lc) and homozygous (gridlc/lc) mice leads to the death of all cerebellar Purkinje cells and most afferent granule neurons. Some studies have indicated that the death of Purkinje cells occurs by apoptosis, and the secondary loss of granule neurons has been shown to require the pro‐apoptotic Bcl‐2 family member Bax. The BH3‐only protein Bim has been shown to contribute to cytokine withdrawal‐induced apoptosis of sympathetic neurons and to be responsible for the kidney degeneration in mice lacking the pro‐survival protein Bcl‐2. Because Bim is expressed strongly in cerebellar Purkinje cells, we have examined whether it has a role in their death in mutant Lurcher mice. Our studies show that Bim deficiency does not modify the Lurcher phenotype, ruling out an indispensable role for Bim in this neurodegenerative disease. © 2003 Wiley‐Liss, Inc.
Transcriptional regulation through glutamate receptors: Involvement of tyrosine kinases
Authors: López‐Bayghen Esther , Aguirre Adán , Ortega Arturo
Published: November 2003

Glutamate receptors play a key role in neuronal plasticity, learning and memory, and in several neuropathologies. Short‐term and long‐term changes in synaptic efficacy are triggered by glutamate. Although an enhanced glutamate‐dependent tyrosine phosphorylation has been described in several systems, its role in membrane‐to‐nuclei signaling is unclear. Taking advantage of the fact that the gene encoding the chick kainate‐binding protein undergoes a glutamate‐dependent transcriptional regulation via an activator protein‐1 (AP‐1) site, we evaluated the involvement of tyrosine kinases in this process. We describe here the participation of receptor and non‐receptor tyrosine kinases in the signaling cascade triggered by glutamate. Our results suggest that in Bergmann glia cells, glutamate receptors transactivate receptor tyrosine kinases, favoring the idea of a complex network of signals activated by this excitatory neurotransmitter that results in regulation of gene expression. © 2003 Wiley‐Liss, Inc.
Mild carbon monoxide exposure and auditory function in the developing rat
Authors: Stockard‐Sullivan Janet E. , Korsak Rose A. , Webber Douglas S. , Edmond John
Published: November 2003

We have examined the influence of chronic mild exposure to carbon monoxide (CO) on cognitive (learning) and auditory function in the developing rat. We have demonstrated that the auditory pathway is compromised at exposures less than 50 ppm, whereas learning was not influenced at 100 ppm. Artificially reared rat pups were exposed to CO during the brain growth spurt and onset of myelination. Spatial learning was assessed using the Morris Water Maze and three tests of auditory function: (1) auditory brainstem conduction times; (2) the amplitude of the eighth nerve's action potential; and (3) otoacoustic emissions carried out on rat pups (age 22– 24 days). The pups were gastrostomy‐reared on a rat milk substitute and chronically exposed to CO at discrete concentrations in the range of 12–100 ppm from 6 days of age to post‐weaning at 21–23 days of age. We found no difference in auditory brainstem conduction times at all CO concentrations in comparison to non‐exposed controls. There was a difference in otoacoustic emissions for test and controls at CO concentrations of 50 ppm but not at lower concentrations. There was a consistent attenuation of the amplitude of the eighth nerve's action potential, even at the lowest CO exposure examined. The attenuation of the amplitude of the action potential of the eighth nerve at 50 ppm carbon monoxide exposure did not completely recover by 73 days of age. We conclude that prolonged mild exposure to carbon monoxide during development causes measurable functional changes at the level of the eighth cranial nerve. © 2003 Wiley‐Liss, Inc.
Estrogen and cognition: Applying preclinical findings to clinical perspectives
Authors: Gibbs Robert B. , Gabor Rachel
Published: November 2003

The effects of hormone replacement therapy on brain aging and cognition are an important public health issue, which, despite much research and debate, has not yet been resolved. In this Mini‐Review, we describe how much of the clinical literature takes on new meaning when interpreted in light of recent preclinical data. We predict, based on these data, that hormone replacement therapy will in fact provide substantial benefit with respect to age‐related cognitive decline, provided that therapy is administered in an appropriate regimen and is initiated within a window of time following the loss of ovarian function. The application of these data to recent clinical findings is discussed. © 2003 Wiley‐Liss, Inc.
Mild carbon monoxide exposure diminishes selectively the integrity of the cochlea of the developing rat
Authors: Lopez Ivan , Acuna Dora , Webber Douglas S. , Korsak Rose A. , Edmond John
Published: November 2003

Rat pups were chronically exposed to carbon monoxide (CO) concentrations (12 or 25 ppm) in air starting at day 8, through 22 days of age, to examine the changes in the peripheral auditory system. Gastrostomy‐reared rat pups, with or without CO exposure, were used and compared with mother‐reared pups. The organ of Corti and the neurons of the spiral ganglion were analyzed for their morphology by using immunochemical and histological techniques. The inner and outer hair cells in the organ of Corti of animals exposed to 12 and 25 ppm CO were not different from the controls. However, at 25 ppm CO exposure, the nerve terminals innervating the inner hair cells were swollen. The somata of neurons in the spiral ganglion showed mild changes in the cytoplasm, and signs of mild vacuolization were observed in myelin covering their central processes. Synaptophysin, a marker for synaptic vesicles, and choline acetyltransferase, a marker for cholinergic terminals, showed no difference in immunoreactivity in CO exposed animals at 12 and at 25 ppm when compared with their age‐matched controls. Also, Na+K+ ATPase immunoreactivity patterns were normal compared with controls. Three enzymes were significantly reduced at the 25 ppm CO exposure: Cytochrome oxidase, NADH‐TR, and calcium ATPase were decreased in both the organ of Corti and the neurons of the spiral ganglion, and decreased immunostaining for the neurofilament and myelin basic proteins was found. We conclude that components of the cochlea are selectively affected by mild chronic CO exposure during development. © 2003 Wiley‐Liss, Inc.
Being there: the acceptance and marginalization of part‐time professional employees
Authors: Lawrence Thomas B. , Corwin Vivien
Published: November 2003

Part‐time professional employees represent an increasingly important social category that challenges traditional assumptions about the relationships between space, time, and professional work. In this article, we examine both the historical emergence of part‐time professional work and the dynamics of its integration into contemporary organizations. Professional employment has historically been associated with being continuously available to one's organization, and contemporary professional jobs often bear the burden of that legacy as they are typically structured in ways that assume full‐time (and greater) commitments of time to the organization. Because part‐time status directly confronts that tradition, professionals wishing to work part‐time may face potentially resistant work cultures. The heterogeneity of contemporary work cultures and tasks, however, presents a wide variety of levels and forms of resistance to part‐time professionals. In this paper, we develop a theoretical model that identifies characteristics of local work contexts that lead to the acceptance or marginalization of part‐time professionals. Specifically, we focus on the relationship between a work culture's dominant interaction rituals and their effects on co‐workers' and managers' reactions to part‐time professionals. We then go on to examine the likely responses of part‐time professionals to marginalization, based on their access to organizational resources and their motivation to engage in strategies that challenge the status quo. Copyright © 2003 John Wiley & Sons, Ltd.
Statistical prediction of global sea‐surface temperature anomalies
Authors: Colman A. W. , Davey M. K.
Published: November 2003

Sea‐surface temperature (SST) is one of the principal factors that influence seasonal climate variability, and most seasonal prediction schemes make use of information regarding SST anomalies. In particular, dynamical atmospheric prediction models require global gridded SST data prescribed through the target season. The simplest way of providing those data is to persist the SST anomalies observed at the start of the forecast at each grid point, with some damping, and this strategy has proved to be quite effective in practice. In this paper we present a statistical scheme that aims to improve that basic strategy by combining three individual methods together: simple persistence, canonical correlation analysis (CCA), and nearest‐neighbour regression. Several weighting schemes were tested: the best of these is one that uses equal weight in all areas except the east tropical Pacific, where CCA is preferred. The overall performance of the combined scheme is better than the individual schemes. The results show improvements in tropical ocean regions for lead times beyond 1 or 2 months, but the skill of simple persistence is difficult to beat in the extratropics at all lead times. Aspects such as averaging periods and grid size were also investigated: results showed little sensitivity to these factors. The combined statistical SST prediction scheme can also be used to improve statistical regional rainfall forecasts that use SST anomaly patterns as predictors. Copyright © Crown Copyright 2003. Published by John Wiley & Sons, Ltd.
Climatic analyses on increasing dust storm frequency in the springs of 2000 and 2001 in Inner Mongolia
Authors: Gao Tao , Su Lijuan , Ma Qingxia , Li Haiying , Li Xicang , Yu Xiao
Published: November 2003

To study the climatic contribution to dust storm increases in Inner Mongolia in recent years, an analysis has been conducted of such factors in the last 40 years as annual and spring (March–May) precipitation, temperature, cold waves and strong gusty winds. In addition, such factors have been studied statistically regarding their impact upon atmospheric circulation with regard to the zonal circulation of Asia, the deep trough over East Asia and the geopotential height of Qinghai–Xizang Plateau. This study shows that the increased occurrences of dust storms likely result from a decrease in annual precipitation during 1999–2001; the precipitation recorded proved to be constantly below average, especially in spring. In addition, warmer temperatures with frequent cold‐air outbreaks created unstable atmospheric stratification, thus leading to more gales and subsequently, more dust storms. In the springs of 2000 and 2001, large‐scale atmospheric circulations provided the conditions for increased occurrences of dust storms due to stronger zonal circulation and a more westerly positioned trough over East Asia that became more intense in the winters. Furthermore, geopotential height over the Qinghai–Xizang Plateau seems to have an opposite trend as against dust storm frequency tendency. El Niño–southern oscillation activity might be an indirect factor. Copyright © 2003 Royal Meteorological Society
Connectivity–splitting models for survivable network design
Authors: Balakrishnan Anantaram , Magnanti Thomas L. , Mirchandani Prakash
Published: November 2003

The survivable network design (SND) problem seeks a minimum‐cost robust network configuration that provides a specified number of alternate (edge‐disjoint) paths between nodes of the network. For this problem, we present a family of new mixed‐integer programming formulations whose associated linear programming relaxations can be tighter than that of the usual cutset formulation. The new formulations, called connectivity‐splitting models, strengthen the cutset formulation by splitting the connectivity requirements across critical cutsets (with crossing requirements of at least two) into two separate requirements and strengthening the connectivity constraints across regular cutsets (with crossing requirements of one). As special cases of this broad modeling approach, we obtain three intuitive versions of the model. A connectivity‐peeling version peels off the lowest connectivity level, a connectivity‐dividing version divides the connectivity requirements for all critical cutsets, and an access‐completion version separates the design decisions for critical cutsets from those for regular cutsets. These stronger formulations motivate several SND combinatorial heuristics and facilitate the analysis of their worst‐case performance. Our bounds on the heuristic costs relative to the optimal values of the integer program and the linear programming relaxation of our tighter formulation are stronger than some previously known performance bounds for combinatorial heuristics. © 2003 Wiley Periodicals, Inc.
Fault‐tolerant cycle embedding in hierarchical cubic networks
Authors: Fu Jung‐Sheng , Chen Gen‐Huey
Published: November 2003

A hierarchical cubic network was proposed as an alternative to the hypercube. By HCN(n), we denote the hierarchical cubic network that contains 2nn‐dimensional hypercubes. In this paper, using Gray codes, we construct fault‐free Hamiltonian cycles in an HCN(n) withn− 1 link faults. Since the HCN(n) is regular of degreen+ 1, the result is optimal. We also construct longest fault‐free cycles of length 22n− 1 in an HCN(n) with a one‐node fault and fault‐free cycles of length at least 22n− 2fin an HCN(n) withf‐node faults, where 22nis the number of nodes in the HCN(n),f≤n− 1 ifn= 3 or 4 andf≤nifn≥ 5. Our results can be applied to the hierarchical folded‐hypercube network as well. © 2003 Wiley Periodicals, Inc.
Edge‐superconnectivity of cages
Authors: Marcote X. , Balbuena C.
Published: November 2003

A graph with minimum degree δ is said to be edge‐superconnected if each minimum edge‐cut consists of all the edges incident with some vertex (so λ = δ). A smallest δ‐regular graph G with girth g is said to be a (δ, g)‐cage. We show that every (δ, g)‐cage with odd girth is edge‐superconnected. This result strengthens one obtained by Wang et al. (λ = δ for every such cage) and supports the conjecture of Fu et al. that all (δ, g)‐cages are δ‐connected. © 2003 Wiley Periodicals, Inc.
Three complete turns of a 310‐helix at atomic resolution: the crystal structure of Z‐(Aib)11‐OtBu
Authors: Gessmann Renate , Brückner Hans , Petratos Kyriacos
Published: November 2003

The crystal structure of the synthetic protected oligopeptide Z‐(Aib)11‐OtBu was determined by x‐ray crystallography. The undecapeptide folds in a regular 310‐helix with nine consecutive 4 → 1 hydrogen bonds. At present, this is the largest available structure of a homopeptide (including homopeptides consisting of standard amino acids) and also the longest observed regular 310‐helix at atomic resolution. Z‐(Aib)11‐OtBu crystallizes readily from hot ethanol–water mixture and is one of the crystals in which no solvent molecule is co‐crystallized. In the crystal head‐to‐tail hydrogen bonded columns are formed in the [1 0 1] direction. Each helical column is surrounded by six others, whereby two are packed in parallel and four in antiparallel fashion. Helical columns are packed via apolar crystal contacts. The crystal structure of Z‐(Aib)11‐OtBu is compared with the crystal structures of Z‐(Aib)10‐OtBu and Z‐(Aib)9‐OtBu. The similarities and differences are analysed. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Crystal structure and conformational analysis of ampullosporin A
Authors: Kronen Matthias , Görls Helmar , Nguyen Hoai‐Huong , Reißmann Siegmund , Bohl Martin , Sühnel Jürgen , Gräfe Udo
Published: November 2003

Ampullosporin A is a 15‐mer peptaibol type polypeptide that induces pigment formation by the fungus Phoma destructiva, forms voltage‐dependent ion channels in membranes and exhibits hypothermic effects in mice. The structure of ampullosporin A has been determined by x‐ray crystallography. This is the first three‐dimensional (3D) structure of the peptaibol subfamily SF6. From the N‐terminus to residue 13 the molecule adopts an approximate right‐handed α‐helical geometry, whereas a less regular structure pattern with β‐turn characteristics is found in the C‐terminus. Even though ampullosporin A does not contain a single proline or hydroxyproline it is significantly bent. It belongs to both the shortest and the most strongly bent peptaibol 3D structures. The straight structure part encompasses residues Ac‐Trp1‐Aib10 and is thus less extended than the α‐helical subunit. The 3D structure of ampullosporin A is discussed in relation to other experimentally determined peptaibol structures and in the context of its channel‐forming properties. As a part of this comparison a novel bending analysis based on a 3D curvilinear axis describing the global structural characteristics has been proposed and applied to all 3D peptaibol structures. A sampling of 2500 conformations using different molecular dynamics protocols yields, for the complete ampullosporin A structure, an α‐helix as the preferred conformation in vacuo with almost no bend. This indicates that solvent or crystal effects may be important for the experimentally observed peptide backbone bending characteristics of ampullosporin A. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Differences in membrane pore formation by peptaibols
Authors: Grigoriev Pavel A. , Schlegel Brigitte , Kronen Matthias , Berg Albrecht , Härtl Albert , Gräfe Udo
Published: November 2003

The efficiencies of membrane pore formation by 14 naturally occurring peptaibols and two structurally modified ampullosporins were compared using an artificial bilayer membrane model. Major differences were found in the dependence on peptide sequences and the constituting amino acids. Alamethicin F‐30, chrysospermins C/D, paracelsin and texenomycin A displayed higher activity by several orders of magnitude in comparison with smaller peptaibols containing <17 amino acids such as ampullosporins, trichofumins, bergofungins and cephaibols. Biological activities such as the induction of pigment formation by the fungus Phoma destructiva and long acting hypothermia and depression of locomotor activity in mice were correlated with moderate membrane permeabilization. No or weak membrane activities corresponded with biological inactivity. Highly membrane‐active structures such as alamethicin F‐30, chrysospermin C, texenomycin A and paracelsin A displayed antibiotic effects against the fungus and toxicity in mice. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Self‐assembling and membrane modifying properties of a lipopeptaibol studied by CW‐ESR and PELDOR spectroscopies
Authors: Milov A. D. , Tsvetkov YU. D. , Formaggio F. , Crisma M. , Toniolo C. , Raap J.
Published: November 2003

Trichogin GA IV is a short lipopeptaibol antibiotic that is capable of enhancing the transport of small cations through the phospholipid double layer of the membrane. The antibiotic activity of the undecapeptide is thought to be based on either its self‐assembling or membrane‐modifying property. The chemical equilibrium between self‐aggregated and non‐aggregated molecular states was studied by CW‐ESR spectroscopy using solutions of TOAC nitroxide spin‐labelled trichogin analogues in an apolar solvent to mimic the membrane bound state. At room temperature the two different sets of signals observed in the spectrum were attributed to the presence of both monomers and aggregates in the sample. The ESR spectra of the monomeric and aggregated forms were separated and the dependence of the fraction of monomeric peptide molecules on concentration was obtained over the range 5 × 10−6 to 7 × 10−4 M. A two‐step aggregation mechanism is proposed: dimerization of peptide molecules followed by aggregation of dimers to assemblies of four peptide molecules per aggregate. The equilibrium constants were estimated for both steps. In addition, the lower lifetime limit was determined for dimers and tetramers. It is shown that when the peptide concentration exceeds 10−5 M, the major part of the peptide molecules in solution has the form of tetrameric aggregates. Independently, the PELDOR technique was used to investigate the concentration dependence of the parameters of the dipole–dipole interaction between spin labels in frozen (77 K) glassy solutions of aggregates of mono‐labelled TOAC analogues. The number of molecules in aggregates as well as the frequency and amplitude of PELDOR signal oscillations were found to be concentration independent in the range 5 × 10−4 to 8 × 10−3 M. In the frozen glassy solution state, the number of peptide molecules per aggregate was determined to be close to four, which is in agreement with the value obtained for spin‐labelled trichogin at room temperature. The present data provide experimental evidence in favour of a self‐assembling rather than a membrane‐modifying ion conduction mechanism. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
The peptaibol database: a sequence and structure resource
Authors: Whitmore L. , Chugh J. K. , Snook C. F. , Wallace B. A.
Published: November 2003

The peptaibols are a large family of membrane‐active peptides with considerable sequence homology, but with different biological properties and three‐dimensional structures. They constitute a rich resource of naturally occurring ‘mutants’ which are potentially valuable for structure/function studies of ion channels.

A searchable on‐line database of sequences and structures of the peptaibols has been created at http://www.cryst.bbk.ac.uk/peptaibol, as a resource for the biological and structural community. In this paper, the contents and organization of the website are discussed as well as procedures for submission of new entries to the database.

At present, more than 300 peptaibol sequences are stored in the database. Each sequence entry contains its full literature reference and information about its biological source. Tools are provided for searching for specific peptaibol sequences or groupings of sequences, and for locating peptaibols containing specified sequence motifs. In addition the website acts as a database for structural information. The coordinates of all currently available peptaibol x‐ray and NMR structures are included and complemented, where appropriate, with molecular graphics illustrations. These include figures of model channel structures and comparisons between different peptaibol structures. The peptaibol database thus provides a tool for ready access to information and a means of investigating the sequences and structures of this class of polypeptides. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Chemical bond modeling with the energy‐driven orbital localization
Authors: Abarenkov I. V. , Antonova I. M.
Published: November 2003

This article concerns the embedding in covalent materials problem in general and the construction of one‐electron pseudoatoms to substitute the parts of a molecule connected with a chemical bond in particular. For this the procedure to part a molecule into the ion‐radicals and bonds within the Hartree–Fock (HF) approach is proposed. In this procedure the ion‐radical occupied orbitals are defined as solutions of HF equations for ion‐radical in the basis of occupied molecular orbitals (MOs) of the whole molecule. The bond orbitals are constructed to complete the functional space span by the occupied MOs of ion‐radicals to the functional space span by occupied MOs of the whole molecule. In this approach it is easy to decompose the total electron density matrix of the whole molecule into the density matrixes of ion‐radicals and bonds. Therefore, the adiabatic potential of the molecule is expressed as a sum of ion‐radical and bonds self‐energies and various intramolecular interaction energies. The equation for the exact bond orbital is developed that is the HF equation for the two‐electron problem in the nonlocal external field and modified Coulomb exchange potential. An approximation for this equation is given. Test calculations were performed for the H2O molecule and the artificial LiOH molecule. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Intermolecular forces and random fields: Mutual renormalizations in classical statistical mechanics
Authors: Zakharov A. Yu.
Published: November 2003

Exact representations of generating functional of one‐component systems with arbitrary central interatomic potentials via functional integral over auxiliary field defined in wave‐vector space are obtained. It is proved that the problem of partition function evaluation is equivalent to the problem of statistical integral of nonlinear (self‐acting) temperature‐dependent field. Elementary excitations Hamiltonian for the continuous model of the classical statistical physics from “first principles” is obtained. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Multireference many‐body perturbation theory calculations on negative ions with small electron detachment energies
Authors: Izmailov Arthur , Zaitsevskii Andréi
Published: November 2003

We present a simple method of ab initio calculations on the systems composed of a closed‐shell‐like molecule (atom) and a weakly bound electron via constructing a state‐specific effective Hamiltonian in a model space generated by placing the extra electron on virtual self‐consistent field orbitals of the neutral species in all the possible ways. Correlation contributions are incorporated into the effective Hamiltonian by the second‐order multipartitioning many‐body perturbation theory. The method prevents the appearance of intruder states without destroying the exact size consistency of results and ensures a proper description of the dynamic correlation effects on the spatial localization of the extra electron and continuous behavior of computed characteristics under variations of molecular geometry. A detailed study of perturbative solutions for a model problem with parameter‐dependent Hamiltonian and test calculations of Ca, Sr, and Ba atomic anions are reported. The method is also applied to the description of the hypothetical symmetrical isomer of water dimer anion with the extra electron trapped between the water molecules. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Design of Statically Stable Walking Robot: A Review
Authors: Kar D. C.
Published: November 2003

The superior mobility characteristics of legged animals compared to those of wheeled or tracked vehicles for off‐road locomotion motivated the development of artificial walking machines. The sustained worldwide efforts for the last few decades resulted in a large number of legged robots with different levels of sophistication. Here, various design approaches made so far to realize artificial legged locomotion are discussed. Mainly, different vehicle configurations as well as leg mechanisms which are already explored by researchers are reviewed in brief. The author hopes that this will serve as a brief account of previous research efforts and help future walking robot designers to develop more sophisticated machines. © 2003 Wiley Periodicals, Inc.
Leukocyte adhesion to cold-preserved rat endothelial cells: Role of actin disassembly and ICAM-1
Authors: Topp Stefan A. , Upadhya Gundumi A. , Strasberg Steven M.
Published: November 2003

Leukocyte adhesion on reperfusion is a critical component of cold preservation injury, and involves increased intercellular adhesion molecule 1 (ICAM-1) expression on sinusoidal endothelial cells (SEC). This study determined whether ICAM-1 expression occurs during cold preservation and whether actin disassembly is necessary for ICAM-1 expression and leukocyte adhesion. ICAM-1 expression was measured in isolated rat SEC during 8 hours of cold preservation by immunofluorescence techniques. Leukocyte adhesion to cold-preserved SEC was measured in an assay using fluorescently labeled leukocytes. The calpain inhibitors N-acetyl-leu-leu-norleucinal/N-acetyl-leu-leu-methioninal and the actin stabilizer phalloidin were added in some studies to prevent actin disassembly. Cold-exposed SEC showed a rapid increase of surface ICAM-1 expression, reaching maximum values in 1 hour. Studies in permeabilized cells suggested that ICAM-1 moved from a perinuclear location to the cell surface. Actin stabilization had no effect on the time-dependent increase in ICAM-1 expression, but seemed to affect the distribution of ICAM-1 on the cell surface. Leukocyte adhesion to SEC correlated with ICAM-1 expression and was reduced to control levels by an anti-ICAM-1 antibody. Although actin stabilization did not reduce ICAM-1 expression, it did reduce leukocyte-SEC adhesion to control values. Increased ICAM-1 expression on cold-preserved SEC is a direct effect of cold. It is not related to actin disassembly, although it seems that actin disassembly affects the distribution of ICAM-1. Leukocyte adhesion to cold-preserved SEC requires both increased ICAM-1 and actin disassembly. Agents that inhibit actin disassembly can significantly decrease leukocyte adhesion regardless of increased ICAM-1 expression.
Gender identity, social influence and children’s arguments
Authors: Leman P. J. , Duveen G.
Published: November 2003

This paper explores the relationship between gender, processes of argumentation and cognitive change in children’s social interaction. Hundredandtwenty children (average age, 9.5 years) discussed a moral dilemma with a same age peer. The style of children’s conversations differed between same sex (boy-boy and girl-girl) pairs and boy-girl pairs. These stylistic differences suggest that the social organisational factors or status relations that stem from a child’s gender group membership can act to obstruct the effective communication and acceptance of certain arguments (or more epistemic aspects of influence) in conversation. Further analysis of conversations points to the importance of addressing differences in perspectives when reaching agreement. Results are discussed with reference to children’s representations and resolutions of socio-cognitive conflict.
A new finite element‐FDTD‐boundary integral equation technique with biconjugate gradient solver for modeling electromagnetic problems in the frequency domain
Authors: Rogier Hendrik , De Zutter Daniël
Published: November 2003

A new hybrid formalism in the frequency domain is presented, based on a combination of the boundary integral equation (BIE) technique, the finite element (FE) method and the finite difference time domain (FDTD) algorithm. An FE method and FDTD are used to describe the inhomogeneous parts of the simulation domain, whereas large homogeneous portions of the simulation space are modeled with a BIE. To solve the global matrix system efficiently, a biconjugate gradient solver is used. To calculate the matrix‐vector products in each iteration step of the solution process, the system matrix is required for the FE and the BIE subregions. For FDTD subregions, we will either construct a system matrix or we will calculate matrix‐vector products directly relying on FDTD. Guidelines will be given to choose the most efficient approach for each FDTD subdomain. To illustrate the efficiency of the new method and to compare the new approach with other (hybrid) methods, three representative configurations are studied.
Surface radiation budgets in support of the GEWEX Continental‐Scale International Project (GCIP) and the GEWEX Americas Prediction Project (GAPP), including the North American Land Data Assimilation System (NLDAS) project
Authors: Pinker Rachel T. , Tarpley J. Dan , Laszlo Istvan , Mitchell Kenneth E. , Houser Paul R. , Wood Eric F. , Schaake John C. , Robock Alan , Lohmann Dag , Cosgrove Brian A. , Sheffield Justin , Duan Qingyun , Luo Lifeng , Higgins R. Wayne
Published: November 2003

In support of the World Climate Research Program GEWEX Continental‐Scale International Project (GCIP) and the GEWEX Americas Prediction Project (GAPP), real‐time estimates of shortwave radiative fluxes, both at the surface and at the top of the atmosphere, are being produced operationally by the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite Data and Information Service using observations from GOES images. The inference scheme has been developed at the Department of Meteorology, University of Maryland, and the atmospheric and surface model input parameters are produced and provided by the NOAA/National Centers for Environmental Prediction. The radiative fluxes are being evaluated on hourly, daily, and monthly timescales using observations at about 50 stations. The satellite estimates have been found to be within acceptable limits during snow‐free periods, but the difficulty in detecting clouds over snow affects the accuracy during the winter season. In what follows, this activity is discussed, and evaluation results of the derived fluxes against ground observations for time periods of 1–2 years are presented.
Lower hybrid waves observed at the dayside polar region: SS‐520‐2 rocket experiment
Authors: Ueda Y. , Kojima H. , Matsumoto H. , Hashimoto K. , Nagano I. , Okada T. , Mukai T.
Published: November 2003

The SS‐520‐2 rocket experiment was carried out over Ny‐alesund, Svalbard, Norway, in the dayside polar region. The onboard Plasma Wave Analyzer (PWA) succeeded in observing waveform data in the 10 Hz to 15 kHz frequency range and high frequency spectrum data up to 3 MHz. These data showed impulsive packet‐like waveforms with frequencies around 3 kHz to 4 kHz as well as auroral hiss emissions. The packet‐like waveforms appeared for the duration of 100–500 ms, and the frequencies of their spectral peaks were well below the lower cutoff frequency of the auroral hiss emissions. Their polarizations, which were identified on the rocket spin plane perpendicular to the ambient magnetic field, were almost linear. The most plausible wave mode is the lower hybrid wave. The PWA has the capability to identify the wave propagation direction and to estimate the corresponding phase velocity using the onboard interferometry system. From the cross correlation in the interferometry system, we estimated the phase velocity of the packet‐like waves to be about 60 km/s. To examine the generation mechanism of the observed lower hybrid waves, we conducted linear dispersion analyses using realistic parameters. Since there was poor correlation between the plasma measurements and the lower hybrid waves, we expect the rocket traversed out of the generation region. As the generation mechanism, we propose the lower hybrid waves excited by electron beams. We calculate the linear dispersion with the existence of electron beams and show the lower hybrid waves are destabilized by electron beams. Under the assumption of an electron beam in the generation region, we found that waves in the frequency range around 3 kHz to 4 kHz were excited with the maximum growth rate just below the lower hybrid resonance frequency. Their frequency was in good agreement with the packet‐like waves.
Ion upflow enhanced by drifting F‐region plasma structure along the nightside polar cap boundary
Authors: Semeter J. , Heinselman C. J. , Thayer J. P. , Doe R. A. , Frey H. U.
Published: November 2003

Conjugate observations by the incoherent scatter radar at Sondrestrom, Greenland, and the Wideband Imaging Camera (WIC) on the IMAGE satellite have been used to establish a causal relationship between drifting F‐region plasma structure in the polar ionosphere and upward ion number flux near the poleward edge of the auroral oval. A longitudinally extended patch of enhanced F‐region density was observed as it advected equatorward across the open‐closed field line boundary and into a region of discrete auroral rays and strong ion upflow (Vi > 800 m/s at 900 km altitude). Upward velocities within the upflow region remained constant during the patch transit, such that the upflowing number flux was directly controlled by F‐region density (both increased by a factor of 2 within the patch). Because polar cap patches and ion upflows are both longitudinally extended, quasi‐stable features of the nightside polar cap boundary, the observed interaction can produce a global‐scale increase in plasma density at higher altitudes where suprathermal outflows are initiated.
New signatures of underground nuclear tests revealed by satellite radar interferometry
Authors: Vincent Paul , Larsen Shawn , Galloway Devin , Laczniak Randell J. , Walter William R. , Foxall William , Zucca John J.
Published: November 2003

New observations of surface displacement caused by past underground nuclear tests at the Nevada Test Site (NTS) are presented using interferometric synthetic aperture radar (InSAR). The InSAR data reveal both coseismic and postseismic subsidence signals that extend one kilometer or more across regardless of whether or not a surface crater was formed from each test. While surface craters and other coseismic surface effects (ground cracks, etc.) may be detectable using high resolution optical or other remote sensing techniques, these broader, more subtle subsidence signals (one to several centimeters distributed over an area 1–2 kilometers across) are not detectable using other methods [Barker et al., 1998]. A time series of interferograms reveal that the postseismic signals develop and persist for months to years after the tests and that different rates and styles of deformation occur depending on the geologic and hydrologic setting and conditions of the local test area.
Hydrous solidus of CMAS‐pyrolite and melting of mantle plumes at the bottom of the upper mantle
Authors: Litasov Konstantin , Ohtani Eiji
Published: November 2003

We showed in previous experiments that the melting temperature of hydrous pyrolite, at the transition boundary between wadsleyite and olivine, is abruptly reduced by the presence of 2 wt.% H2O. In this paper we determine the apparent solidus for CaO‐MgO‐Al2O3‐SiO2‐pyrolite with lower and geologically more reasonable H2O contents (0.5 wt.%). Phase relations and melt compositions have been determined at pressures of 13.5–17.0 GPa and temperatures of 1600 to 2100°C. There was no abrupt decrease of solidus temperature along the phase boundary between olivine and wadsleyite in pyrolite with 0.5 wt.% H2O. However significant gradual decrease of the solidus temperature at pressures below 15–16 GPa still supports previous models for a hydrous origin of some ancient komatiites by dehydration melting of rising wet plumes at pressures of 4–10 GPa.
Assessing the water use of short vegetation and forests: Development of the Hydrological Land Use Change (HYLUC) model
Authors: Calder Ian R.
Published: November 2003

This paper describes the theoretical background and recent developments to the present version of the Hydrological Land Use Change (HYLUC) model which has been used to investigate the impacts of land use change, particularly changes relating to forest cover, on water resources in many countries of the world. The model makes use of the “limits” concept and the Penman equation to ensure parsimony in terms both of data requirements (daily rainfall, daily potential transpiration, and land cover data) and in terms of the parameters required to take account of the different evaporative responses of different vegetation types. The model is applicable both for research and land and water resource management purposes (where input data is generally very limited).
Zina and the Moral Regulation of Pakistani Women
Authors: Khan Shahnaz
Published: November 2003

From 1998 to 1999, I interviewed women who had been incarcerated under the Zina Ordinance ( zina means illicit sex) in Pakistan. This led me to an examination of women's moral regulation by their families, a process in which I maintain the state is complicit. I argue against relativist explanations of this process, which view Pakistani culture or notions of timeless Islam as the reason for women's incarceration. Instead, I examine the interconnection of morality with the legal/judicial structures, the relationship between the state and patriarchy within families, and the plight of impoverished women in Pakistan within an era of globalization. In my analysis, I link economic development and human rights to globalization and the continuing costs of militarization. Such connections allow feminists to target the structural conditions that sustain the laws in Pakistan and help create an environment that will bring about the repeal of the laws while contributing to trans-national feminist solidarity.