bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interrupting Vibrio cholerae infection of human epithelial cells with engineered commensal bacterial signaling
Authors: Duan Faping , March John C. 
Published: March 2008

AbstractVibrio cholerae El Tor serotypes are largely responsible for outbreaks of cholera in the developing world. The infection cycle for some strains of V. cholerae is coordinated, at least in part, through quorum sensing. That is, the expression of virulence genes depends on the concentration of V. cholerae autoinducers cholera autoinducer 1 (CAI‐1) and autoinducer 2 (AI‐2). High concentrations of CAI‐1 and AI‐2 have been shown previously to inhibit virulence gene expression. We have demonstrated here that a commensal bacterium, E. coli Nissle 1917 (Nissle), can be engineered to express CAI‐1 (Nissle expresses AI‐2 natively) and effectively interrupt V. cholerae virulence. We engineered Nissle to express CAI‐1 under control of the lac promoter, and demonstrated inhibition of V. cholerae expression of cholera toxin (CT, as indicated by presence of the CT subunit B (CTB)) and of the toxin co‐regulated pilus (TCP, as indicated by the relative transcript of TCP subunit A (TCPA)) in both monocultures of V. cholerae and co‐cultures with epithelial cells, Nissle, and V. cholerae. In the model system of Caco‐2 epithelia incubated with V. cholerae, we demonstrated that co‐cultures with Nissle expressing CAI‐1 activity reduced CTB binding to Caco‐2 cells by 63% over co‐cultures with wild‐type Nissle. Further, cultures with Nissle expressing CAI‐1 had significantly lower TCPA transcription than controls with wild‐type Nissle. These results represent a significant step towards a prophylactic method for combating enteric disease through engineered quorum signaling within a commensal bacterial strain. Biotechnol. Biotechnol. Bioeng. 2008;101: 128–134. © 2008 Wiley Periodicals, Inc.
Time‐lapse analysis and microdissection of living 3D melanoma cell cultures for genomics and proteomics
Authors: Demou Zoe N. 
Published: March 2008

AbstractA novel technique is presented for the monitoring and morphological characterization of 3D cell cultures targeted for laser capture microdissection (LCM). A custom‐made chamber enables time‐lapse topography and pre‐selection of cell targets in order to minimize microdissection time, optimizing the quality of biomolecules for downstream analyses. The method complements the recently presented novel application of LCM in living 3D cultures, whose compatibility with standard genomics and proteomics assays such as microarrays, real‐time PCR, and 2D gel electrophoresis is further corroborated here. Specifically, the above techniques are employed in tandem to study, as a proof of principle, the dynamics of in vitro vasculogenic mimicry. It was shown previously that aggressive melanoma cells spontaneously differentiate on collagen gels into vascular‐like networks with strong endogenous angiogenic potential. Here the evolution of vasculogenic mimicry was quantified by three time‐dependent variables: the distribution of the vascular‐like network lengths, widths, and area coverage. Based on these morphological descriptors the networks were locally classified over time as “early” or “mature” stage. LCM of networks and randomly oriented cells followed by real‐time PCR for select genes revealed that differential expression was time‐dependent and increased with network maturity. The method is widely applicable for microgenomics and microproteomics analyses in phenotypically evolving 3D cultures (i.e., of stem cells), under spontaneous or directed differentiation. Therefore beyond enabling future rigorous analyses on the mechanistics of vasculogenic mimicry, it provides a practical discovery engine for a range of developmental studies and tissue regenerative engineering applications. Biotechnol. Bioeng. 2008;101: 307–316. © 2008 Wiley Periodicals, Inc.
Human bone derived cell culture on PLGA flat sheet membranes of different lactide:glycolide ratio
Authors: Ellis Marianne J. , Chaudhuri Julian B. 
Published: March 2008

AbstractProviding a scaffold that can supply nutrients on a large scale (several cubic centimeters) is the key to successfully regenerating vascularized tissue: biodegradable membranes are a promising new scaffold suited to this purpose. Poly(lactic‐co‐glycolic‐acid) (PLGA) flat sheet membranes of different lactide:glycolide ratios, prepared by phase inversion using 1‐methyl‐2‐pyrrolidinone (NMP) as the solvent and water as the nonsolvent, were compared by assessing attachment, proliferation and osteogenic function of human bone derived cells (HBDC). Three different lactide:glycolide ratios, 50:50, 75:25, and 100:0, were compared to tissue culture polystyrene (TCPS). For attachment, 50:50 and 75:25 had similar numbers to TCPS but 100:0 had significantly fewer cells than TCPS. 50:50 and 75:25 had significantly lower HBDC numbers after 7 days but 100:0 had similar numbers compared to TCPS. For proliferation the cell number on the membranes were similar to each other. After 3 weeks, osteoblastic function of the HBDC, shown by mineralization and alkaline phosphatase activity, was present but was significantly lower compared to the TCPS control but similar when the membranes were compared. PLGA membranes fabricated from a range of ratios support HBDC culture so the optimum scaffold composition can be selected based on other factors, such as degradation rate. Biotechnol. Bioeng. 2008;101: 369–377. © 2008 Wiley Periodicals, Inc.
Structure–Catalytic Activity Relationship in Bridging Silacycloalkyl Ring Conformations of Constrained Geometry Titanium Complexes
Authors: Kang Eugene , Kim Sung‐Kwan , Kim Tae‐Jin , Chung Jae‐Ho , Hahn Jong Sok , Ko Jaejung , Ok Myung‐Ahn , Cheong Minserk , Kang Sang Ook 
Published: March 2008

AbstractA series of cyclic silylene‐bridged (amidocyclopentadienyl)dichlorotitanium(IV) complexes [TiCl2{η5‐1‐(CySitBuN‐κN)‐2,3,4,5‐R4‐C5}] was prepared, where CySi = silacyclobutyl (a), silacyclopentenyl (b), silacyclopentyl (c), and silacyclohexyl (d); R = H (4), Me (5). The starting silane, dichlorosilacycloalkane CySiCl2 (1), was treated with NaCp (LiCp*), followed by LiNHtBu to yield the cyclic silylene‐bridged ligands (R4C5)CySi(NHtBu) [R = H (2); Me (3)]. Subsequent deprotonation with n‐butyllithium, followed by transmetalation with TiCl4 yielded the desired constrained geometry complexes (CGCs) (CpCySiNtBu)TiCl2 (4) and (Cp*CySiNtBu)TiCl2 (5). The structures of the resulting cyclopentadienyl‐ (4b and 4c) and tetramethylcyclopentadienyl(silacycloalkyl)amidotitanium(IV) dichloride (5a, 5c, and 5d) species were studied by using X‐ray crystallography to obtain geometrical information on cyclic silylene‐modified CGCs. The ethylene polymerization by the cyclic silylene‐bridged CGCs 4 and 5 was examined to verify the structure–catalytic activity relationship derived from variation of the size of a cyclic silylene ring. Indeed, the size of the cyclic silylene ring at the 1,1′‐position of 4 and 5 affected the catalytic activities through the ethylene polymerization. Systematic increase in the catalytic activities was observed as the cyclic silylene‐bridging unit was expanded from a four‐ to six‐membered ring. In the present study, we found that CGCs of TiIV with a six‐membered silylene‐bridged ligand (5d) produced active catalytic species for the formation of polyethylene with Mw = 42.7 × 10–4 g mol–1 and Mw/Mn = 2.1 with excellent catalytic activities (20.9 kg polymer per mmol of Ti). When titanium(IV) dimethyl complex (6d) was applied in continuous polymerization process, impressive high catalytic activity on copolymerization with 1‐octene was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Hybrid formulation of operator splitting (OS) and Newmark‐β methods for collaborative structural analysis (CSA)
Authors: Pan Peng , Tada Motohide 
Published: March 2008

AbstractA collaborative structural analysis (CSA) system is developed, which is capable of performing highly sophisticated structural analyses utilizing beneficial features of existing individual structural analysis programs. In the system, the global equations of motion for the overall structural system are formulated in the host program. Some substructures, whose behaviors are relatively simple, are directly solved in the host program, whereas those having complex behavior are analyzed by the station programs. A time‐consuming static condensation procedure is needed for the substructures analyzed by the station programs if adopting an implicit integration scheme. The operator splitting (OS) method, which does not require tangential stiffness, can be used to improve the system efficiency. To this end, a hybrid formulation of the Newmark‐β and OS methods is proposed, and a CSA scheme based on the hybrid formulation is developed. In the CSA system adopting the hybrid formulation, the degrees of freedom whose tangential stiffness are unavailable are formulated by the OS method, whereas the rest are still formulated by the commonly used Newmark‐β method. Using the system, analyses of a three‐story‐braced steel moment‐resisting frame are conducted. In the analyses, the column bases are analyzed using the commercial finite element method software ABAQUS, and the remaining structural elements are analyzed using a frame analysis program called NETLYS. Results suggest that the hybrid formulation is very effective for the CSA system. Copyright © 2008 John Wiley & Sons, Ltd.
Glacial geomorphology of the Central Arctic Ocean: the Chukchi Borderland and the Lomonosov Ridge
Authors: Jakobsson Martin , Polyak Leonid , Edwards Margo , Kleman Johan , Coakley Bernard 
Published: March 2008

AbstractThe last decade of geophysical seafloor mapping in the Arctic Ocean from nuclear submarines and icebreakers reveals a wide variety of glaciogenic geomorphic features at water depths reaching 1000 m. These findings provide new and intriguing insights into the Quaternary glacial history of the Northern Hemisphere. Here we integrate multi‐ and single beam bathymetric data, chirp sonar profiles and sidescan images from the Chukchi Borderland and Lomonosov Ridge to perform a comparative morphological seafloor study. This investigation aims to elucidate the nature and provenance of ice masses that impacted the Arctic Ocean sea floor during the Quaternary. Mapped glaciogenic bedforms include iceberg keel scours, most abundant at water depths shallower than ∼350–400 m, flutes and megascale glacial lineations extending as deep as ∼1000 m below the present sea level, small drumlin‐like features and morainic ridges and grounding‐zone wedges. The combination of these features indicates that very large glacial ice masses extended into the central Arctic Ocean from surrounding North American and Eurasian ice sheets several times during the Quaternary. Ice shelves occupied large parts of the Arctic Ocean during glacial maxima and ice rises were formed over the Chukchi Borderland and portions of the Lomonosov Ridge. More geophysical and sediment core data combined with modeling experiments are needed to reconstruct the timing and patterns of these events. Copyright © 2008 John Wiley & Sons, Ltd.
Geological constraints on Antarctic palaeo‐ice‐stream retreat
Authors: Cofaigh Colm Ó , Dowdeswell Julian A. , Evans Jeffrey , Larter Rob D. 
Published: March 2008

AbstractSubmarine landforms preserved in bathymetric troughs on the Antarctic continental shelf show that the style of ice stream retreat across the shelf following the last glacial maximum varied between different troughs. Three styles of retreat are inferred from the geological evidence: rapid, episodic and slow. Rapid retreat by ice stream floatation and calving is recorded by the preservation of a landform assemblage of unmodified streamlined subglacial bedforms including mega‐scale glacial lineations (MSGLs) that record streaming flow along these troughs. These elongate bedforms are not overprinted by recessional glacial landforms formed transverse to ice flow such as moraines or grounding‐zone wedges, and overlying deglacial sediments are thin. A second type of landform assemblage consists of MSGLs overprinted or interrupted by transverse grounding‐zone wedges. This assemblage implies episodic retreat between successive grounding‐zone positions. The third type of landform assemblage is that of numerous, closely spaced, recessional moraines and intermittent grounding‐zone wedges that overlie and interrupt MSGLs. This assemblage records the slow retreat of grounded ice across the shelf. Variation in the style of ice stream retreat between the different bathymetric troughs indicates that Antarctic palaeo‐ice‐streams did not respond uniformly to external forcing at the end of the last glacial cycle. Rather, their diachronous retreat reflects the dominance of local controls in the form of bathymetry and drainage basin size. More broadly, these data show that retreat of marine‐based ice sheets in areas of reverse bed slope is not necessarily catastrophic, and they provide important constraints for numerical models that attempt to predict the dynamics of large polar ice sheets. Copyright © 2008 John Wiley & Sons, Ltd.
Antarctic subglacial topography and ice‐sheet evolution
Authors: Siegert Martin J. 
Published: March 2008

AbstractAlthough ice‐sheet flow and form in Antarctica is controlled to a large degree by topography, the continent's landscape evolution and therefore its influence on ice‐sheet development is poorly understood. The oscillation of ice sheets throughout the last 34 million years will have affected topography through glacial erosion and deposition. Consequently, the macro bedforms on which the modern ice sheet flows originate from previous, and probably dissimilar, ice sheets. This problem is both obvious and difficult to resolve given the lack of bed exposure and paucity of data concerning sedimentary deposits. Nonetheless, several attempts have been made, using numerical modelling, to comprehend the interrelation between topography and ice sheets in Antarctica. In this review, the subglacial topography of Antarctica is inspected with reference to both contemporary ice‐flow processes and ice‐sheet history. Examples of how landscape evolution have been estimated are discussed, which provides a means by which the continental scale link between topography and ice‐sheet development can be investigated in future. Copyright © 2008 John Wiley & Sons, Ltd.
Superimposition of ribbed moraines on a palaeo‐ice‐stream bed: implications for ice stream dynamics and shutdown
Authors: Stokes Chris R. , Lian Olav B. , Tulaczyk Slawek , Clark Chris D. 
Published: March 2008

AbstractThe sediments and landforms preserved on palaeo‐ice‐stream beds can provide important information about their subglacial conditions and flow mechanisms, and the processes accompanying their shutdown. In this paper, detailed observations of an intriguing subglacial landform assemblage of ribbed moraines superimposed on glacial lineations on the Dubawnt Lake Ice Stream bed (north‐west Canadian Shield) are presented, including their morphometry, internal structure (from ground penetrating radar (GPR) surveys and from glaciogeological analysis) and sedimentological characteristics (from sediment architecture and lithofacies analysis). The observations suggest an abrupt change in ice dynamics that correlates with two phases of glacial landform development. This hypothesis is based on evidence from a deformed lodgement till, which subsequently underwent brittle deformation and developed prominent thrust (shear) structures and tension fractures. Tension fractures are observed in a sediment exposure and thrust structures are observed in GPR surveys, where they occur most prominently in the ribbed moraine ridge crests. The presence of the fractures, and their association with a population of clasts in the till that are orientated with their a‐axes transverse to the inferred ice flow direction, suggests a compressional flow regime. It is therefore inferred that the glacial lineations were formed under an extensional flow regime during ice stream activity, but that at some point patches of till under the ice stream stiffened through dewatering. The subsequent increase in basal shear stress resulted in compressional flow and the development of subglacial thrusting and the building of ribbed moraines. We therefore suggest that ribbed moraines may form in areas of compressional flow under ice streams, i.e. sticky spots, and/or at the transition between slow and fast ice flow along parts of an ice stream. The general absence of ribbed moraines on most other palaeo‐ice‐stream beds suggests that either these ice streams continued operating during deglaciation or processes other than the development of localized compressional flow (sticky spots) led to their shutdown (e.g. ice depletion). Copyright © 2008 John Wiley & Sons, Ltd.
A two‐dimensional prototype multi‐physics model of the right ventricle of the heart
Authors: Croft T. N. , Williams A. J. , Slone A. K. , Cross M. 
Published: March 2008

AbstractThe heart operates as a delicate function of the interactions among its electro‐chemical, structural and fluid components. The objective of this paper is to describe the computational modelling of the interaction between simplified forms of the electro‐chemical, structural and fluid behaviour. It is because the objective here is to evaluate the interactions among the phenomena that the specific models of the electro‐chemical, fluid and structural behaviour are kept as simple as possible. The electro‐chemical model is drawn from that of Clayton and Holden, while the blood is assumed to be a conventional slightly compressible Navier–Stokes fluid and the heart wall is a simple elastic structure modelled via the static equations. The model is implemented within a multi‐physics finite volume solver environment using an unstructured mesh approach, which enables the implementation of models for each of the specific phenomenon and their interactions. The model is two dimensional, but shows how the electric field drives a cross section of the wall so that it pumps the blood in and out of the right ventricle geometry. Copyright © 2008 John Wiley & Sons, Ltd.
Multiphase modelling of pouring glass over the spout lip of an industrial float in the flat glass forming process
Authors: Fernández Oro J. M. , Argüelles Díaz K. M. , Santolaria Morros C. , Cobo Hedilla A. F. , Lemaille M. 
Published: March 2008

AbstractThis paper describes the numerical modelling of the three‐phase flow that is established when pouring molten glass onto a tin bath (float) under a non‐reactive atmosphere. Discharged from the furnace, the glass is spouted over a lip onto the bath, where it floats and spreads out in the form of a long ribbon, leading to the flat glass forming process. Numerically, the physical modelling must consider a multiphase problem with three immiscible phases: glass, tin and air. The simulation of this complex free‐surface flow involves the solution of the Navier–Stokes set of equations for all the phases simultaneously, using a volume‐of‐fluid formulation that introduces a marker function convected by the flow to identify each phase. The evolution of the interphases is tracked over time with the implementation of a continuous surface force algorithm. A general purpose, well‐tested commercial code, FLUENT, is employed for the computations. Firstly, a two‐dimensional model considering the symmetry plane of the float is developed to fit accurate physical and numerical parameters. The high complexity of the interphases in addition to great differences between the physical properties of the phases has required extensive tests to ensure the consistency and accuracy of the solutions. Afterwards, a complete three‐dimensional model is built to simulate the pouring process in a real geometry and predict the behaviour of the industrial facility when the operating conditions are modified. Typical flow phenomena inside the tin bath, such as tin currents, wet back flow or even the equilibrium thickness, are also obtained as a promising result of the numerical modelling. Copyright © 2008 John Wiley & Sons, Ltd.
Identification of midbrain floor plate radial glia‐like cells as dopaminergic progenitors
Authors: Bonilla Sonia , Hall Anita C. , Pinto Luisa , Attardo Alessio , Götz Magdalena , Huttner Wieland B. , Arenas Ernest 
Published: March 2008

AbstractThe floor plate (FP), a signaling center and a structure rich in radial glia‐like cells, has been traditionally thought to be devoid of neurons and neuronal progenitors. However, in the midbrain, the FP contains neurons of the dopaminergic (DA) lineage that require contact with radial glia‐like cells for their induction. We, therefore, decided to explore the interaction relationship between radial glia and neurons during DA neurogenesis. Taking advantage of a novel FP radial glia‐like cell culture system and retroviruses, DA neurons were lineage traced in vitro. In utero BrdU pulse‐chases extensively labeled the midbrain FP and traced DA neurons both in vivo and in FP cultures. Moreover, from E9.5 to E13.5 the midbrain FP contained dividing cells only in the most apical part of the neuroepithelium, in cells identified as radial glia‐like cells. We, therefore, hypothesized that midbrain FP radial glia‐like cells could be DA progenitors and tested our hypothesis in vivo. Lineage tracing of DA progenitors with EGFP in Tis21‐EGFP knock‐in mice, and genetic fate mapping in GLAST::CreERT2/ZEG mice identified the neuroepithelium of the midbrain FP, and specifically, GLAST+ radial glia‐like cells as DA progenitors. Combined, our experiments support the concept that the midbrain FP differs from other FP regions and demonstrate that FP radial glia‐like cells in the midbrain are neurogenic and give rise to midbrain DA neurons. © 2008 Wiley‐Liss, Inc.
The duration effect: a link between TTO and VAS values
Authors: Craig Benjamin M. 
Published: March 2008

AbstractThe value of a health state may depend on how long an individual has had to endure the health state (i.e. hedonic load). In this paper, we test the constant proportionality (CP) assumption and determine the sign of relationship between duration and health state value for 42 health states using the nationally representative data from the United Kingdom Measurement and Valuation of Health study. The results reject the CP assumption and suggest that the relationship is negative for optimal health (i.e. fair innings argument) and that the relationship is positive for poorer health states (i.e. adaptation). We find no evidence of the maximum endurable time hypothesis using these data. This evidence on the duration effect has important implications for outcomes research and the economic evaluation of interventions. Copyright © 2008 John Wiley & Sons, Ltd.
Older siblings influence younger siblings' motor development
Authors: Berger Sarah E. , Nuzzo Katie 
Published: March 2008

AbstractEvidence exists for two competing theories about the effects of having an older sibling on development. Previous research has found that having an older sibling has both advantages and disadvantages for younger siblings' development. This study examined whether and how older siblings influenced the onset of their own younger siblings' motor milestones, a heretofore unstudied developmental domain in the sibling literature. Parents of 51 sibling pairs reported their children's crawling and walking onset dates. In keeping with imitation theories, in families where younger siblings crawled or walked earlier than their own older sibling, they did so significantly earlier. Moreover, in keeping with limited parental resource theories, in families where older siblings crawled or walked earlier than their own younger sibling, they did so significantly earlier. Older siblings did influence younger siblings' motor development, but how they did so may have depended on unique family characteristics. Copyright © 2008 John Wiley & Sons, Ltd.