bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotational structure in the asymmetric OH stretch of Cs+(H2O)Ar
Authors: Vaden Timothy D. , Forinash Brian , Lisy James M.
Published: September 2002

Evaporative cooling, which is the usual mode of formation for many ion–molecule complexes, typically results in high internal energies. This in turn leads to a broadening of vibrational or vibronic spectra of these species. By incorporating argon into the nascent ion cluster, it is possible to significantly reduce the internal energy and thus simplify the spectra. This approach has been applied to the Cs+(H2O) cluster ion. The binding of argon lowers the internal energy to an effective temperature of 125 K. Rotational structure in the asymmetric stretch can be analyzed to conclude that the structure of Cs+(H2O)Ar is quasi-linear with the heavy atoms in an Ar–Cs+–O configuration and the two hydrogen atoms symmetrically displaced off–axis, pointing away from the ion.
Time-resolved terahertz emission spectroscopy of wide miniband GaAs/AlGaAs superlattices
Authors: Shimada Y. , Hirakawa K. , Lee S.-W.
Published: September 2002

We have investigated terahertz (THz) emission due to dynamical electron transport in wide miniband GaAs/Al0.3Ga0.7As superlattices by time-resolved THz emission spectroscopy. Quasiautocorrelation measurements were performed on the emitted THz electromagnetic waves by using a bolometer as a wideband detector. The bias-field dependence of the emitted THz radiation intensity clearly showed a crossover from the miniband transport to the formation of Wannier–Stark ladder. In the Wannier–Stark regime, a few cycle Bloch oscillations were observed even at 300 K in a superlattice whose miniband width is greater than the longitudinal optical phonon energy. Furthermore, it has been found that clear Bloch oscillations are visible only when the bottom of the miniband is photoexcited.
Lateral-cavity spectral hole burning in quantum-dot lasers
Authors: Ouyang D. , Heitz R. , Ledentsov N. N. , Bognár S. , Sellin R. L. , Ribbat Ch. , Bimberg D.
Published: September 2002

Spectral hole burning effects are observed as strong spectral intensity modulations in the emission spectra of broad and narrow stripe quantum-dot lasers with ridge waveguide. The modulation is attributed to lateral-cavity resonances burning holes in the inhomogeneously broadened spectral gain profile of the quantum dots. Lateral cavity engineering is expected to be crucial for optimizing quantum-dot laser performance and for potential realizing of wavelength-stabilized devices.
Formation of InAs quantum dot arrays on GaAs (100) by self-organized anisotropic strain engineering of a (In,Ga)As superlattice template
Authors: Mano T. , Nötzel R. , Hamhuis G. J. , Eijkemans T. J. , Wolter J. H.
Published: September 2002

We demonstrate the formation of well-defined InAs quantum dot (QD) arrays by self-organized engineering of anisotropic strain in a (In,Ga)As/GaAs superlattice (SL). Due to the accumulation and improvement of the uniformity of the strain-field modulation along [011], formation of InAs QD arrays along [0-11] with 140 nm lateral periodicity is clearly observed on the SL template when the number of SL periods is larger than ten. By enhancing the In adatom surface migration length at low growth rates, clear arrays of single InAs QDs are obtained. The QD arrays exhibit strong photoluminescence efficiency that is not reduced compared to that from InAs QD layers on GaAs. Hence, ordering by self-organized anisotropic strain engineering maintains the high structural quality of InAs QDs.
Thermal poling of glass modified by femtosecond laser irradiation
Authors: Corbari Costantino , Mills John D. , Deparis Olivier , Klappauf Bruce G. , Kazansky Peter G.
Published: September 2002

Thermal poling of silica glass modified by femtosecond laser irradiation is demonstrated. Increase of second-harmonic generation in the irradiated regions is observed. This enhancement is interpreted in terms of structural modifications in silica glass that make the poling process more efficient. Evidence of a change in the distribution of the electrostatic field frozen in glass during poling is obtained. This technique is used for χ(2) grating fabrication.
Effective microwave ferrite convolver using a dielectric resonator
Authors: Kobljanskyj Yu. V. , Melkov G. A. , Serga A. A. , Tiberkevich V. S. , Slavin A. N.
Published: September 2002

A highly effective microwave convolver with extended frequency range is proposed and experimentally tested. This convolver uses nonlinear interaction of two dipolar spin wave (or backward volume magnetostatic wave) signals contrapropagating from the ends in a ferrite film placed inside an open dielectric resonator. The output signal, proportional to the convolution of the input signals, is received by the resonator, and is transmitted to a load through a regular waveguide. The proposed convolver does not have a strict upper limit for signal frequency, and at a signal frequency of 4.67 GHz has a record value of bilinearity coefficient of B=−11.7 dB W.
Status of water quality at Holbox Island, Quintana Roo State, Mexico
Authors: Tran Kim Chi , Valdes David , Euan Jorge , Real Elizabeth , Gil Eloy
Published: September 2002

Holbox Island (with its coastal lagoon, Yalahau Lagoon) located in the littoral zone at the north-eastern tip of the Yucatan Peninsula, Gulf of Mexico, is a relatively undisturbed ecosystem that is currently under threat from unplanned and intensive urban development. Although other ecosystems in this littoral zone have been studied to determine the basic requirements for sustainable development, little information about Holbox Island exists. Thus far, no data concerning coastal pollution in Yalahau Lagoon have been published. As part of a larger, on-going study, this article reports the results of analyses to determine the temporal and spatial variations of standard physical and chemical parameters and to evaluate the relationships among these parameters. Water and sediment samples collected from 42 stations during two seasons of the year (rainy and dry seasons) were analyzed using standard methods. The results indicate that, in general, the area is relatively undisturbed by human influence. Dissolved oxygen content was lower than 4 ml l−1 and the percentage of oxygen saturation lower than 90%, suggesting that the site supports higher consumption than production of oxygen. Nitrogen is mostly present as ammonium and low concentrations of nitrate; nitrite, and phosphate indicate that eutrophication is not widespread in the area. Sediments are mostly sandy,containing less than 10% organic matter at most stations. The redox potential of sediments was negative for all samples. Water quality at stations in the proximity of boating and dumping activities shows higher degradation than at other stations within the lagoon. These preliminary results provide the opportunity to construct a baseline for coastal water quality,prior to impending urban development, and may serve to determine whether the future natural and development processes have impact on the conditions and health of coastal ecosystems around Holbox Island. In addition, because the area is, as yet, relatively undisturbed, the data reported here allow us to take stock of the extent to which other sites in the Yucatan littoral zone have already been degraded by human development activities.
Biodiversity of periphyton (diatoms) and echinoderms around a refinery effluent, and possible associations with stability
Authors: Izsak C. , Price A. R. G. , Hardy J. T. , Basson P. W.
Published: September 2002

We examine biodiversity in Tarut Bay, Saudi Arabia, around the effluent of a refinery that has operated since 1945. The spatial study involved quarterly assessment of diatom biodiversity in 1976/77 at 24 sites. Taxonomic distinctness decreased significantly towards the refinery outfall, in contrast to the pattern for number of species, Simpson'sindex and Margalef'sspecies richness index. Ammonia-nitrogen concentrations and primary productivity (mg chlorophyll-a cm−1 d−1) also increased significantly towards the effluent, probably due to nearby sewage/nutrient enrichment.

The spatio-temporal assessment involved comparison of echinoderm biodiversity at eight sites in 1945 through 1947 and 1977. No significant temporal differences were observed in number of species, taxonomic distinctness or beta-diversity, nor was significant correlation detected between biodiversity and proximity to the refinery outfall. The absence of obvious impact is confirmed by statistical comparison of taxonomic distinctness for echinoderms in Tarut Bay with values for the whole Gulf.

Periphyton in Tarut Bay may be perturbed towards the refinery outfall, ‘positively’ when measured by Simpson's and other ‘absolute’ biodiversity measures, but ‘negatively’ according to taxonomic distinctness, a measure of ‘average’ properties. Hence, diatom persistence stability appears moderate to low. In contrast, the echinoderm fauna may exhibit high stability, explained by either high persistence (withstanding perturbation), or high resilience (perturbation experienced, but system reverted or acclimated to ‘normal’ Gulf state) over a time scale of 30 y.
c-junis essential for sympathetic neuronal death induced by NGF withdrawal but not by p75 activation
Authors: Palmada M. , Kanwal S. , Rutkoski N.J. , Gustafson-Brown C. , Johnson R.S. , Wisdom R. , Carter B.D.
Published: September 2002

Sympathetic neurons depend on NGF binding to TrkA for their survival during vertebrate development. NGF deprivation initiates a transcription-dependent apoptotic response, which is suggested to require activation of the transcription factor c-Jun. Similarly, apoptosis can also be induced by selective activation of the p75 neurotrophin receptor. The transcriptional dependency of p75-mediated cell death has not been determined; however, c-Jun NH2-terminal kinase has been implicated as an essential component. Because the c-jun–null mutation is early embryonic lethal, thereby hindering a genetic analysis, we used the Cre-lox system to conditionally delete this gene. Sympathetic neurons isolated from postnatal day 1 c-jun–floxed mice were infected with an adenovirus expressing Cre recombinase or GFP and analyzed for their dependence on NGF for survival. Cre immunopositive neurons survived NGF withdrawal, whereas those expressing GFP or those uninfected underwent apoptosis within 48 h, as determined by DAPI staining. In contrast, brain-derived neurotrophic factor (BDNF) binding to p75 resulted in an equivalent level of apoptosis in neurons expressing Cre, GFP, and uninfected cells. Nevertheless, cycloheximide treatment prevented BDNF-mediated apoptosis. These results indicate that whereas c-jun is required for apoptosis in sympathetic neurons on NGF withdrawal, an alternate signaling pathway must be induced on p75 activation.
Plakoglobin is required for maintenance of the cortical actin skeleton in early Xenopus embryos and for cdc42-mediated wound healing
Authors: Kofron Matthew , Heasman Janet , Lang Stephanie A. , Wylie Christopher C.
Published: September 2002

Early Xenopus embryos are large, and during the egg to gastrula stages, when there is little extracellular matrix, the cytoskeletons of the individual blastomeres are thought to maintain their spherical architecture and provide scaffolding for the cellular movements of gastrulation. We showed previously that depletion of plakoglobin protein during the egg to gastrula stages caused collapse of embryonic architecture. Here, we show that this is due to loss of the cortical actin skeleton after depletion of plakoglobin, whereas the microtubule and cytokeratin skeletons are still present. As a functional assay for the actin skeleton, we show that wound healing, an actin-based behavior in embryos, is also abrogated by plakoglobin depletion. Both wound healing and the amount of cortical actin are enhanced by overexpression of plakoglobin. To begin to identify links between plakoglobin and the cortical actin polymerization machinery, we show here that the Rho family GTPase cdc42, is required for wound healing in the Xenopus blastula. Myc-tagged cdc42 colocalizes with actin in purse-strings surrounding wounds. Overexpression of cdc42 dramatically enhances wound healing, whereas depletion of maternal cdc42 mRNA blocks it. In combinatorial experiments we show that cdc42 cannot rescue the effects of plakoglobin depletion, showing that plakoglobin is required for cdc42-mediated cortical actin assembly during wound healing. However, plakoglobin does rescue the effect of cdc42 depletion, suggesting that cdc42 somehow mediates the distribution or function of plakoglobin. Depletion of α-catenin does not remove the cortical actin skeleton, showing that plakoglobin does not mediate its effect by its known linkage through α-catenin to the actin skeleton. We conclude that in Xenopus, the actin skeleton is a major determinant of cell shape and overall architecture in the early embryo, and that plakoglobin plays an essential role in the assembly, maintenance, or organization of this cortical actin.
BubR1 is essential for kinetochore localization of other spindle checkpoint proteins and its phosphorylation requires Mad1
Authors: Chen Rey-Huei
Published: September 2002

The spindle checkpoint delays anaphase onset until all chromosomes have attached properly to the mitotic spindle. Checkpoint signal is generated at kinetochores that are not bound with spindle microtubules or not under tension. Unattached kinetochores associate with several checkpoint proteins, including BubR1, Bub1, Bub3, Mad1, Mad2, and CENP-E. I herein show that BubR1 is important for the spindle checkpoint in Xenopus egg extracts. The protein accumulates and becomes hyperphosphorylated at unattached kinetochores. Immunodepletion of BubR1 greatly reduces kinetochore binding of Bub1, Bub3, Mad1, Mad2, and CENP-E. Loss of BubR1 also impairs the interaction between Mad2, Bub3, and Cdc20, an anaphase activator. These defects are rescued by wild-type, kinase-dead, or a truncated BubR1 that lacks its kinase domain, indicating that the kinase activity of BubR1 is not essential for the spindle checkpoint in egg extracts. Furthermore, localization and hyperphosphorylation of BubR1 at kinetochores are dependent on Bub1 and Mad1, but not Mad2. This paper demonstrates that BubR1 plays an important role in kinetochore association of other spindle checkpoint proteins and that Mad1 facilitates BubR1 hyperphosphorylation at kinetochores.
Human TPX2 is required for targeting Aurora-A kinase to the spindle
Authors: Kufer Thomas A. , Silljé Herman H.W. , Körner Roman , Gruss Oliver J. , Meraldi Patrick , Nigg Erich A.
Published: September 2002

Aurora-A is a serine-threonine kinase implicated in the assembly and maintenance of the mitotic spindle. Here we show that human Aurora-A binds to TPX2, a prominent component of the spindle apparatus. TPX2 was identified by mass spectrometry as a major protein coimmunoprecipitating specifically with Aurora-A from mitotic HeLa cell extracts. Conversely, Aurora-A could be detected in TPX2 immunoprecipitates. This indicates that subpopulations of these two proteins undergo complex formation in vivo. Binding studies demonstrated that the NH2 terminus of TPX2 can directly interact with the COOH-terminal catalytic domain of Aurora-A. Although kinase activity was not required for this interaction, TPX2 was readily phosphorylated by Aurora-A. Upon siRNA-mediated elimination of TPX2 from cells, the association of Aurora-A with the spindle microtubules was abolished, although its association with spindle poles was unaffected. Conversely, depletion of Aurora-A by siRNA had no detectable influence on the localization of TPX2. We propose that human TPX2 is required for targeting Aurora-A kinase to the spindle apparatus. In turn, Aurora-A might regulate the function of TPX2 during spindle assembly.
Synergistic Activation of ENaC by Three Membrane-bound Channel-activating Serine Proteases (mCAP1, mCAP2, and mCAP3) and Serum- and Glucocorticoid-regulated Kinase (Sgk1) inXenopusOocytes
Authors: Vuagniaux Grégoire , Vallet Véronique , Jaeger Nicole Fowler , Hummler Edith , Rossier Bernard C.
Published: September 2002

Sodium balance is maintained by the precise regulation of the activity of the epithelial sodium channel (ENaC) in the kidney. We have recently reported an extracellular activation of ENaC-mediated sodium transport (INa) by a GPI-anchored serine protease (mouse channel–activating protein, mCAP1) that was isolated from a cortical collecting duct cell line derived from mouse kidney. In the present study, we have identified two additional membrane-bound serine proteases (mCAP2 and mCAP3) that are expressed in the same cell line. We show that each of these proteases is able to increase INa 6–10-fold in the Xenopus oocyte expression system. INa and the number (N) of channels expressed at the cell surface (measured by binding of a FLAG monoclonal I125-radioiodinated antibody) were measured in the same oocyte. Using this assay, we show that mCAP1 increases INa 10-fold (P < 0.001) but N remained unchanged (P = 0.9), indicating that mCAP1 regulates ENaC activity by increasing its average open probability of the whole cell (wcPo). The serum- and glucocorticoid-regulated kinase (Sgk1) involved in the aldosterone-dependent signaling cascade enhances INa by 2.5-fold (P < 0.001) and N by 1.6-fold (P < 0.001), indicating a dual effect on N and wcPo. Compared with Sgk1 alone, coexpression of Sgk1 with mCAP1 leads to a ninefold increase in INa (P < 0.001) and 1.3-fold in N (P < 0.02). Similar results were observed for mCAP2 and mCAP3. The synergism between CAPs and Sgk1 on INa was always more than additive, indicating a true potentiation. The synergistic effect of the two activation pathways allows a large dynamic range for ENaC-mediated sodium regulation crucial for a tight control of sodium homeostasis.
Modeling Tight Junction Dynamics and Oscillations
Authors: Kassab Fuad , Marques Ricardo Paulino , Lacaz-Vieira Francisco
Published: September 2002

Tight junction (TJ) permeability responds to changes of extracellular Ca2+ concentration. This can be gauged through changes of the transepithelial electrical conductance (G) determined in the absence of apical Na+. The early events of TJ dynamics were evaluated by the fast Ca2+ switch assay (FCSA) (Lacaz-Vieira, 2000), which consists of opening the TJs by removing basal calcium (Ca2+bl) and closing by returning Ca2+bl to normal values. Oscillations of TJ permeability were observed when Ca2+bl is removed in the presence of apical calcium (Ca2+ap) and were interpreted as resulting from oscillations of a feedback control loop which involves: (a) a sensor (the Ca2+ binding sites of zonula adhaerens), (b) a control unit (the cell signaling machinery), and (c) an effector (the TJs). A mathematical model to explain the dynamical behavior of the TJs and oscillations was developed. The extracellular route (ER), which comprises the paracellular space in series with the submucosal interstitial fluid, was modeled as a continuous aqueous medium having the TJ as a controlled barrier located at its apical end. The ER was approximated as a linear array of cells. The most apical cell is separated from the apical solution by the TJ and this cell bears the Ca2+ binding sites of zonula adhaerens that control the TJs. According to the model, the control unit receives information from the Ca2+ binding sites and delivers a signal that regulates the TJ barrier. Ca2+ moves along the ER according to one-dimensional diffusion following Fick's second law. Across the TJ, Ca2+ diffusion follows Fick's first law. Our first approach was to simulate the experimental results in a semiquantitative way. The model tested against experiment results performed in the frog urinary bladder adequately predicts the responses obtained in different experimental conditions, such as: (a) TJ opening and closing in a FCSA, (b) opening by the presence of apical Ca2+ and attainment of a new steady-state, (c) the escape phase which follows the halt of TJ opening induced by apical Ca2+, (d) the oscillations of TJ permeability, and (e) the effect of Ca2+ap concentration on the frequency of oscillations.
Allen & Overy – premier in people development
Authors: Eales‐White Rupert
Published: September 2002

Describes the approach and the innovations introduced into management development in one of the leading global law firms. Outlines the introduction of a “top‐down” approach and its growth that, over time, created a culture where development was seen as a necessary, positive and welcome experience. Describes the recent overhaul of “management development” in the firm, and the introduction of a continuous development process. Notes that, in the programme, staff are effectively developed in the areas on which they will be assessed, as well as being prepared for more challenging roles in the future; performance is maximised as well as motivation.
Improving workforce development
Authors: Powell Andy
Published: September 2002

Looks at the need for high performance working, outlines its characteristics and examines ways in which workforce development can be improved. Explains the history of workforce development, its growing importance and the current low level of understanding amongst UK organisations, proposing the formation of a new “sector learning highway” and outlining how it could work. Suggests that industry‐specified standards will increasingly become legal requirements and that a “licence to operate” will no longer be restricted to those working within the professions. Gives working examples to illustrate the points made and includes examples of sector information and advice currently available across a number of industries.
Radical self‐development – a bottom up perspective
Authors: Bagshaw Mike , Bagshaw Caroline
Published: September 2002

Self‐development of employees is essential if businesses are to thrive. Technology has brought new techniques, of which e‐learning is one of the more publicised. There has been a great deal of experimentation, some of it more successful than others. One ingredient, motivation, remains essential to the success of any development plan. Personal contact is an important part of this. Now e‐learning is out of its infancy, there has been a move towards blended learning – a mix of different learning methods to optimise the effect of all of them. There is a radical initiative from Sweden, which combines personal coaching with Web‐based training. It takes as its pivotal point the motivation of the employee. Aligning individual goals with organisational objectives is integral to the programme.
An exploratory study of work motivation among private and public sector hospital chefs in Australia
Authors: Lee‐Ross Darren
Published: September 2002

This paper assesses the reliability and rationale of Hackman and Oldham’s job characteristics model among public and private sector hospital chefs in Australia. It continues by focusing on critical job elements of chefs and their motivational outcomes. The job of chef in private sector hospitals was found to be more challenging with greater motivating potential than that in the public sector. Reliance of hospitality services managers upon technology appears to have resulted in a deskilled production process and, consequently, a demotivated workforce.
Collaborative computing technology: the hot new managing tool
Authors: Attaran Mohsen , Attaran Sharmin
Published: September 2002

In a few years, the Internet has gone from being the communication tool of scientists to a primary route of information exchange for everyone, from fashion designers to financial analysts. The Internet and its related services create an interactive working environment for users. Through the Internet, effective collaboration becomes possible whenever, wherever, and with whomever. Recently, there has been a significant growth in collaborative products and services aimed at small and mid‐sized businesses. The aim of this paper is to discuss the evolution of the collaborative computing technology and address the capabilities of this new managing tool. The trends in collaborative products and services and some of the collaborative computing products generating the most interest will be examined.
An identification and classification of enterprise portal functions and features
Authors: Raol Jaydip M. , Koong Kai S. , Liu Lai C. , Yu Chun S.
Published: September 2002

Enterprise portal is a type of new information system that can help companies and their employees to manage, share, and use previously disparate information. There are more than 60 vendors that are offering corporate portal solutions. With so many vendors, selecting the right one can be a difficult task. The primary objective of this research is to identify and evaluate the functions and features in enterprise portal products. In particular, this study develops a simplified model that can be used for identifying and classifying the functions and features in corporate portal software. The results of this study may be useful to information technology managers, educators, and students involved in knowledge management, business intelligence, information systems resources management, and data management. System developers, software engineers, project managers, financial managers, and data architects can use the functions and features identified in this study as benchmarking tools for evaluating portals capabilities.
A framework for analyzing e‐commerce security
Authors: Kesh Someswar , Ramanujan Sam , Nerur Sridhar
Published: September 2002

This paper presents a framework for analyzing e‐commerce security. The framework is developed by analyzing the relationships between e‐commerce security needs, threats, technologies and tools. Organizations can use the framework to evaluate and select security for e‐commerce.
A structure for the yeast prohibitin complex: Structure prediction and evidence from chemical crosslinking and mass spectrometry
Authors: Back Jaap W. , Sanz Marta Artal , de Jong Luitzen , de Koning Leo J. , Nijtmans Leo G.J. , de Koster Chris G. , Grivell Les A. , van der Spek Hans , Muijsers Anton O.
Published: September 2002

The mitochondrial prohibitin complex consists of two subunits (PHB1 of 32 kD and PHB2 of 34 kD), assembled into a membrane‐associated supercomplex of approximately 1 MD. A chaperone‐like function in holding and assembling newly synthesized mitochondrial polypeptide chains has been proposed. To further elucidate the function of this complex, structural information is necessary. In this study we use chemical crosslinking, connecting lysine side chains, which are well scattered along the sequence. Crosslinked peptides from protease digested prohibitin complexes were identified with mass spectrometry. From these results, spatial restraints for possible protein conformation were obtained. Many interaction sites between PHB1 and PHB2 were found, whereas no homodimeric interactions were observed. Secondary and tertiary structural predictions were made using several algorithms and the models best fitting the spatial restraints were selected for further evaluation. From the structure predictions and the crosslink data we derived a structural building block of one PHB1 and one PHB2 subunit, strongly intertwined along most of their length. The size of the complex implies that approximately 14 of these building blocks are present. Each unit contains a putative transmembrane helix in PHB2. Taken together with the unit building block we postulate a circular palisade‐like arrangement of the building blocks projecting into the intermembrane space.
Molecular modeling‐based analysis of interactions in the RFC‐dependent clamp‐loading process
Authors: Venclovas Česlovas , Colvin Michael E. , Thelen Michael P.
Published: September 2002

Replication and related processes in eukaryotic cells require replication factor C (RFC) to load a molecular clamp for DNA polymerase in an ATP‐driven process, involving multiple molecular interactions. The detailed understanding of this mechanism is hindered by the lack of data regarding structure, mutual arrangement, and dynamics of the players involved. In this study, we analyzed interactions that take place during loading onto DNA of either the PCNA clamp or the Rad9‐Rad1‐Hus1 checkpoint complex, using computationally derived molecular models. Combining the modeled structures for each RFC subunit with known structural, biochemical, and genetic data, we propose detailed models of how two of the RFC subunits, RFC1 and RFC3, interact with the C‐terminal regions of PCNA. RFC1 is predicted to bind PCNA similarly to the p21‐PCNA interaction, while the RFC3‐PCNA binding is proposed to be similar to theE. coliδ‐β interaction. Additional sequence and structure analysis, supported by experimental data, suggests that RFC5 might be the third clamp loader subunit to bind the equivalent PCNA region. We discuss functional implications stemming from the proposed model of the RFC1‐PCNA interaction and compare putative clamp‐interacting regions in RFC1 and its paralogs, Rad17 and Ctf18. Based on the individual intermolecular interactions, we propose RFC and PCNA arrangement that places three RFC subunits in association with each of the three C‐terminal regions in PCNA. The two other RFC subunits are positioned at the two PCNA interfaces, with the third PCNA interface left unobstructed. In addition, we map interactions at the level of individual subunits between the alternative clamp loader/clamp system, Rad17‐RFC2–5/Rad9‐Rad1‐Hus1. The proposed models of interaction between two clamp/clamp loader pairs provide both structural framework for interpretation of existing experimental data and a number of specific findings that can be subjected to direct experimental testing.
Mapping and characterization of the functional epitopes of tissue inhibitor of metalloproteinases (TIMP)‐3 using TIMP‐1 as the scaffold: A new frontier in TIMP engineering
Authors: Lee Meng‐Huee , Maskos Klaus , Knäuper Vera , Dodds Philippa , Murphy Gillian
Published: September 2002

Tumor necrosis factor‐α (TNF‐α) converting enzyme (TACE/ADAM‐17) is responsible for the release of TNF‐α, a potent proinflammatory cytokine associated with many chronic debilitating diseases such as rheumatoid arthritis. Among the four variants of mammalian tissue inhibitor of metalloproteinases (TIMP‐1 to ‐4), TACE is specifically inhibited by TIMP‐3. We set out to delineate the basis for this specificity by examining the solvent accessibility of every epitope on the surface of a model of the truncated N‐terminal domain form of TIMP‐3 (N‐TIMP‐3) in a hypothetical complex with the crystal structure of TACE. The epitopes suspected of interacting with TACE were systematically transplanted onto N‐TIMP‐1. We succeeded in transforming N‐TIMP‐1 into an active inhibitor for TACE (Kiapp 15 nM) with the incorporation of Ser4, Leu67, Arg84, and the TIMP‐3 AB‐loop. The combined effects of these epitopes are additive. Unexpectedly, introduction of “super‐N‐TIMP‐3” epitopes, defined in our previous work, only impaired the affinity of N‐TIMP‐1 for TACE. Our mutagenesis results indicate that TIMP‐3‐TACE interaction is a delicate process that requires highly refined surface topography and flexibility from both parties. Most importantly, our findings confirm that the individual characteristics of TIMP could be transplanted from one variant to another.
CxxS: Fold‐independent redox motif revealed by genome‐wide searches for thiol/disulfide oxidoreductase function
Authors: Fomenko Dmitri E. , Gladyshev Vadim N.
Published: September 2002

Redox reactions involving thiol groups in proteins are major participants in cellular redox regulation and antioxidant defense. Although mechanistically similar, thiol‐dependent redox processes are catalyzed by structurally distinct families of enzymes, which are difficult to identify by available protein function prediction programs. Herein, we identified a functional motif, CxxS (cysteine separated from serine by two other residues), that was often conserved in redox enzymes, but rarely in other proteins. Analyses of complete Escherichia coli, Campylobacter jejuni, Methanococcus jannaschii, and Saccharomyces cerevisiae genomes revealed a high proportion of proteins known to use the CxxS motif for redox function. This allowed us to make predictions in regard to redox function and identity of redox groups for several proteins whose function previously was not known. Many proteins containing the CxxS motif had a thioredoxin fold, but other structural folds were also present, and CxxS was often located in these proteins upstream of an α‐helix. Thus, a conserved CxxS sequence followed by an α‐helix is typically indicative of a redox function and corresponds to thiol‐dependent redox sites in proteins. The data also indicate a general approach of genome‐wide identification of redox proteins by searching for simple conserved motifs within secondary structure patterns.
Newcastle Disease Virus (NDV) Marker Vaccine: an Immunodominant Epitope on the Nucleoprotein Gene of NDV Can Be Deleted or Replaced by a Foreign Epitope
Authors: Mebatsion Teshome , Koolen Marck J. M. , de Vaan Leonie T. C. , de Haas Niels , Braber Marian , Römer-Oberdörfer Angela , van den Elzen Paul , van der Marel Pieter
Published: September 2002

The nucleoprotein (NP) of Newcastle disease virus (NDV) functions primarily to encapsidate the virus genome for the purpose of RNA transcription, replication, and packaging. This conserved multifunctional protein is also efficient in inducing NDV-specific antibody in chickens. Here, we localized a conserved B-cell immunodominant epitope (IDE) spanning residues 447 to 455 and successfully generated a recombinant NDV lacking the IDE by reverse genetics. Despite deletion of NP residues 443 to 460 encompassing the NP-IDE, the mutant NDV propagated in embryonated specific-pathogen-free chicken eggs to a level comparable to that of the parent virus. In addition, a B-cell epitope of the S2 glycoprotein of murine hepatitis virus (MHV) was inserted in-frame to replace the NP-IDE. Recombinant viruses properly expressing the introduced MHV epitope were successfully generated, demonstrating that the NP-IDE not only is dispensable for virus replication but also can be replaced by foreign sequences. Chickens immunized with the hybrid recombinants produced specific antibodies against the S2 glycoprotein of MHV and completely lacked antibodies directed against the NP-IDE. These marked-NDV recombinants, in conjunction with a diagnostic test, enable serological differentiation of vaccinated animals from infected animals and may be useful tools in ND eradication programs. The identification of a mutation-permissive region on the NP gene allows a rational approach to the insertion of protective epitopes and may be relevant for the design of NDV-based cross-protective marker vaccines.
Slowly Declining Levels of Viral RNA and DNA in DNA/Recombinant Modified Vaccinia Virus Ankara-Vaccinated Macaques with Controlled Simian-Human Immunodeficiency Virus SHIV-89.6P Challenges
Authors: Tang Yuyang , Villinger Francois , Staprans Silvija I. , Amara Rama Rao , Smith James M. , Herndon James G. , Robinson Harriet L.
Published: September 2002

In a recent vaccine trial, we showed efficient control of a virulent simian-human immunodeficiency virus SHIV-89.6P challenge by priming with a Gag-Pol-Env-expressing DNA and boosting with a Gag-Pol-Env- expressing recombinant-modified vaccinia virus Ankara. Here we show that long-term control has been associated with slowly declining levels of viral RNA and DNA. In the vaccinated animals both viral DNA and RNA underwent an initial rapid decay, which was followed by a lower decay rate. Between 12 and 70 weeks postchallenge, the low decay rates have had half-lives of about 20 weeks for viral RNA in plasma and viral DNA in peripheral blood mononuclear cells and lymph nodes. In vaccinated animals the viral DNA has been mostly unintegrated and has appeared to be largely nonfunctional as evidenced by a poor ability to recover infectious virus in cocultivation assays, even after CD8 depletion. In contrast, in control animals, which have died, viral DNA was mostly integrated and a larger proportion appeared to be functional as evidenced by the recovery of infectious virus. Thus, to date, control of the challenge infection has appeared to improve with time, with the decay rates for viral DNA being at the lower end of values reported for patients on highly active antiretroviral therapy.
Phenotypic and Functional Alterations of Dendritic Cells Induced by Human Herpesvirus 6 Infection
Authors: Kakimoto Miki , Hasegawa Atsuhiko , Fujita Shigeru , Yasukawa Masaki
Published: September 2002

Human herpesvirus 6 (HHV-6) has a tropism for T lymphocytes and monocytes/macrophages, suggesting that HHV-6 infection affects the immunosurveillance system. In the present study, we investigated the HHV-6-induced phenotypic and functional alterations of dendritic cells (DCs), which are professional antigen-presenting cells. HHV-6 infection of monocyte-derived immature DCs appeared to induce the up-regulation of CD80, CD83, CD86, and HLA class I and class II molecules, suggesting that HHV-6 infection induces the maturation of DCs. In addition, the antigen capture capacity of DCs was found to decrease following infection with HHV-6. In contrast to up-regulation of mature-DC-associated surface molecules on HHV-6-infected DCs, their capacity for presentation of alloantigens and exogenous virus antigens to T lymphocytes decreased significantly from that of uninfected DCs. In contrast, there appeared to be no reduction in the capacity for presentation of an HLA class II-binding peptide to the peptide-specific CD4+T lymphocytes. These data indicate that HHV-6 infection induces phenotypic alterations and impairs the antigen presentation capacity of DCs. The present data also suggest that the dysfunction of HHV-6-infected DCs is attributable mainly to impairment of the antigen capture and intracellular antigen-processing pathways.
Improved Hepatic Gene Transfer by Using an Adeno-Associated Virus Serotype 5 Vector
Authors: Mingozzi Federico , Schüttrumpf Jörg , Arruda Valder R. , Liu Yuhong , Liu Yi-Lin , High Katherine A. , Xiao Weidong , Herzog Roland W.
Published: September 2002

Adeno-associated viral (AAV) vectors have been shown to direct stable gene transfer and expression in hepatocytes, which makes them attractive tools for treatment of inherited disorders such as hemophilia B. While substantial levels of coagulation factor IX (F.IX) have been achieved using AAV serotype 2 vectors, use of a serotype 5 vector further improves transduction efficiency and levels of F.IX transgene expression by 3- to 10-fold. In addition, the AAV-5 vector transduces a higher proportion of hepatocytes (∼15%). The subpopulations of hepatocytes transduced with either vector widely overlap, with the AAV-5 vector transducing additional hepatocytes and showing a wider area of transgene expression throughout the liver parenchyma.
Specificity and Affinity of Sialic Acid Binding by the Rhesus Rotavirus VP8* Core
Authors: Dormitzer Philip R. , Sun Zhen-Yu J. , Blixt Ola , Paulson James C. , Wagner Gerhard , Harrison Stephen C.
Published: September 2002

Nuclear magnetic resonance spectroscopy demonstrates that the rhesus rotavirus hemagglutinin specifically binds α-anomeric
N
-acetylneuraminic acid with a

K
d

of 1.2 mM. The hemagglutinin requires no additional carbohydrate moieties for binding, does not distinguish 3′ from 6′ sialyllactose, and has approximately tenfold lower affinity for
N
-glycolylneuraminic than for
N
-acetylneuraminic acid. The broad specificity and low affinity of sialic acid binding by the rotavirus hemagglutinin are consistent with this interaction mediating initial cell attachment prior to the interactions that determine host range and cell type specificity.
Protective Antiviral Immune Responses to Pseudorabies Virus Induced by DNA Vaccination Using Dimethyldioctadecylammonium Bromide as an Adjuvant
Authors: van Rooij Eugene M. A. , Glansbeek Harrie L. , Hilgers Luuk A. T. , te Lintelo Eddie G. , de Visser Yolanda E. , Boersma Wim J. A. , Haagmans Bart L. , Bianchi Andre T. J.
Published: September 2002

To enhance the efficacy of a DNA vaccine against pseudorabies virus (PRV), we evaluated the adjuvant properties of plasmids coding for gamma interferon or interleukin-12, of CpG immunostimulatory motifs, and of the conventional adjuvants dimethyldioctadecylammonium bromide in water (DDA) and sulfolipo-cyclodextrin in squalene in water. We demonstrate that a DNA vaccine combined with DDA, but not with the other adjuvants, induced significantly stronger immune responses than plasmid vaccination alone. Moreover, pigs vaccinated in the presence of DDA were protected against clinical disease and shed significantly less PRV after challenge infection. This is the first study to demonstrate that DDA, a conventional adjuvant, enhances DNA vaccine-induced antiviral immunity.
ABELIAN VARIETIES OF TYPE III AND THE HODGE CONJECTURE
Authors: ABDULALI SALMAN
Published: September 2002

We show that the algebraicity of Weil's Hodge cycles implies the usual Hodge conjecture for a general member of a PEL-family of abelian varieties of type III. We deduce the general Hodge conjecture for certain 6-dimensional abelian varieties of type III, and the usual Hodge and Tate conjectures for certain 4-dimensional abelian varieties of type III.
EXISTENCE OF HERMITIAN–EINSTEIN METRICS ON STABLE HIGGS BUNDLES OVER OPEN KÄHLER MANIFOLDS
Authors: LI JIAYU , WANG YOU-DE
Published: September 2002

In this paper we consider the existence of Hermitian–Einstein metrics on stable Higgs bundles over open Kähler manifolds and establish the Bogomolov–Gieseker inequality on the stable Higgs bundles. These results improve some theorems in [21] due to Carlos Simpson.
BROWNIAN MOTION IN A TWO-DIMENSIONAL POTENTIAL: A NEW NUMERICAL SOLUTION METHOD
Authors: CHEN L. Y.
Published: September 2002

Studying the Brownian motion of a particle in a two-dimensional potential with two saddle-point passages connecting two wells, we compute the activation rate of the particle from one well into the other and illustrate a new technique for obtaining numerical solution to the Langevin equation for transition probability. By virtue of a Langevin equation with negative friction, this new method directly traces the active part of an activation event, without having to simulate the long period of small fluctuations in a well between two successful events, and computes the statistical weight for each successful activation. It makes feasible for us to numerically integrate the Langevin equation for transition probability even when the activation energy barrier (i.e. the potential difference between the saddle point and the well) is much greater than thermal energy k B T where other methods fail to be tractable.
A COMPLETE SYSTEM FOR INTERPRETATION OF COLOR MAPS
Authors: ABLAMEYKO S. , BEREISHIK V. , HOMENKO M. , LAGUNOVSKY D. , PARAMONOVA N. , PATSKO O.
Published: September 2002

The paper describes a system and technology for the automatic/interactive interpretation of color maps. Due to the fact that a completely automatic solution is impossible, a combination of automatic and interactive techniques is used. Firstly, color recognition and separation is performed. For automatic map vectorization, a special fast scheme is used. To make digitization more automatic and user-friendly, an interactive digitizing mode has been developed to extract line-based cartographic objects from vectorised data. The system has a powerful and friendly user interface that is described in the paper. The system is used successfully in the digitization of topographic and other types of map.
Hypoxia-inducible erythropoietin gene expression in human neuroblastoma cells
Authors: Stolze Ineke , Berchner-Pfannschmidt Utta , Freitag Patricia , Wotzlaw Christoph , Rössler Jochen , Frede Stilla , Acker Helmut , Fandrey Joachim
Published: September 2002

Two human neuroblastoma (NB) cell lines, SH-SY5Y and Kelly, were found to express the gene for erythropoietin (EPO) in an oxygen (O2)-dependent manner. However, NB cells had maximal production of EPO with lower partial pressure of O2 values than the well-characterized hepatoma cell line HepG2. This maximal EPO expression was preceded by accumulation of the O2-sensitive α subunit of the heterodimeric transcription-factor complex hypoxia-inducible factor 1 (HIF-1). Western blot analysis revealed that the amount of the β subunit of HIF-1, identical to aryl hydrocarbon receptor nuclear translocator 1 (ARNT1), and the homolog ARNT2 increased in nuclear extracts from SH-SY5Y cells exposed to anoxia. In neuronal cells, ARNT1 and ARNT2 can form a heterodimer with HIF-1α, generating a functional HIF-1 complex. Using the hypoxia response element of the human EPO enhancer, we conducted electrophoretic mobility shift assays that showed accumulation and binding of HIF-1 complexes containing both ARNT1 and ARNT2 in NB cells. In addition to the HIF-1 complex, hepatocyte nuclear factor 4α (HNF4α) was found to be indispensable for hypoxia-induced EPO gene expression in hepatoma cells. Western blot analysis and polymerase chain reaction assessment showed that NB cells express neither HNF4α nor the splicing variant HNF4α7 and thus express EPO in an HNF4α-independent manner. Together, SH-SY5Y and Kelly cells may provide a new in vitro model for studying the mechanism of tissue-specific, hypoxia-inducible EPO gene expression.
Lack of α2-antiplasmin promotes pulmonary heart failure via overrelease of VEGF after acute myocardial infarction
Authors: Matsuno Hiroyuki , Kozawa Osamu , Yoshimi Naoki , Akamatsu Shigeru , Hara Akira , Mori Hideki , Okada Kiyotaka , Ueshima Shigeru , Matsuo Osamu , Uematsu Toshihiko
Published: September 2002

Identification of a novel therapy for prevention of sudden death by ischemic cardiac infarction is an area of intensive investigation. We here report that the mortality due to an experimental acute myocardial infarction (AMI) was markedly increased in mice deficient in α2-antiplasmin (α2-AP−/− mice) but not in mice deficient in other components acting in fibrinolysis (tissue-type PA, urokinase type PA, or plasminogen activator inhibitor-1) even if the infarct area in α2-AP−/− mice was not different from those in the other mice. Echocardiography showed in α2-AP−/− mice after AMI an overload of the right ventricle and that pulmonary permeability was increased. According to the experiments using explanted myocytes and vascular smooth muscle cells, it was found that the amount of secreted vascular endothelial cell growth factor (VEGF) in α2-AP−/− mice was markedly increased compared with that in wild-type mice. Finally, an injection of an anti-VEGF antibody decreased the mortality after AMI in α2-AP−/− mice. Plasmin cleaves extracellular matrix-bound VEGF to release a diffusible proteolytic fragment and is inactivated mainly by α2-AP. Therefore, lack of α2-AP could markedly result in overrelease of VEGF by the continuous activation of plasmin because of AMI and could result in an acute cor pulmonale. Our results provide new aspects on the role of α2-AP and VEGF in the pathogenesis of cardiac events.