bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined “heat transfer and power dissipation” optimization of nanofluid flows
Authors: Gosselin Louis , da Silva Alexandre K.
Published: November 2004

This letter exercises the importance of maximizing the thermal performance of nanofluid flows under appropriate constraints. Laminar and turbulent boundary layer flows in forced and natural convection are considered. The objective is to maximize the heat transfer rate removed from a warm plate by the nanofluid. In forced convection, the power dissipation is constrained to highlight the competing effects of the thermal conductivity and viscosity variations due to the presence of the particles. In natural convection, the competition is intrinsic to the problem formulation. The amount of particles is optimized in each case.
Generation and detection of terahertz radiation by electro-optical process in GaAs using 1.56μm fiber laser pulses
Authors: Nagai Masaya , Tanaka Koichiro , Ohtake Hideyuki , Bessho Toshiaki , Sugiura Toshiharu , Hirosumi Tomoya , Yoshida Makoto
Published: November 2004

We report the generation and detection of a terahertz wave with a nonresonant electro-optical crystal using 1.56μm femtosecond laser pulses. Using a 0.5-mm-thick (110)-oriented GaAs wafer for optical rectification and electro-optical modulation, we detected spectral sensitivity below 3THz. We also estimated the availability of GaAs from the viewpoint of an electro-optical coefficient and phase match condition.
Towards plasmonic band gap laser
Authors: Okamoto Takayuki , H’Dhili Fekhra , Kawata Satoshi
Published: November 2004

A two-dimensional periodically corrugated silver surface prohibits the propagation of the surface plasmons in all lateral directions. And band gaps are generated in the dispersion relation, named plasmonic band gaps. At the edge of this band gap, surface plasmons are laterally confined as standing waves. We investigate this phenomenon for lasing action by the use of a dye film deposited on a corrugated silver surface. Fluorescence of the dye was strongly enhanced. Indeed, we obtained an enhancement factor 150 for a methyl-red doped poly (methylmethacrylate) film and 3 for an evaporated 4-dicyanomethylene-2-methyl-6-p-dimethyl-aminostyryl-4H-pyran film. We also discuss the conditions under which lasing action may occur.
Magnetic anisotropy of Fe3Pt alloy thin films
Authors: Nahid M. A. I. , Suzuki Takao
Published: November 2004

The magnetic anisotropy constants of Fe3Pt alloy thin films grown onto MgO(100) and MgO(111) substrates by electron-beam evaporation are investigated in conjunction with structure. It is observed that the orientation of the Fe3Pt films depends on the substrate. Both oriented samples exhibit very large in-plane magnetic anisotropy. The magnetic anisotropy constants K1 and K2 are found to strongly depend on the deposition temperature (TS). The maximum values of K1 and K2 obtained are about −4×106 and 2×107erg∕cc, respectively. A close relationship is observed between the magnetic anisotropy constants and structural parameter.
Analyzing Planning and Design Discourses
Authors: Kumar Sandeep , Pallathucheril Varkki George
Published: November 2004

The term ‘discourse’ is used to describe the entangled and contested transactions through which real-world planning and policy issues are addressed. Studies of discourses have become an important way of understanding how power is mediated in planning, but the methods through which discourses are identified and evaluated is as yet unclear in the literature. Here, we describe our attempt—with still only limited success—to map discourses using a method that extends the work of Toulmin and Gasper and George. Our method consists of a tabular representation of argument structure to depict the content and structure of a discourse, and a graphical index to the discourse table to reveal higher order patterns in the discourse. Using discourse pertaining to a real-life design-review case, we demonstrate how our approach allows us to understand the internal structure of that discourse better. We conclude with suggestions for how the method might be further improved.
Human Movement Behaviour in Urban Spaces: Implications for the Design and Modelling of Effective Pedestrian Environments
Authors: Willis Alexandra , Gjersoe Nathalia , Havard Catriona , Kerridge Jon , Kukla Robert
Published: November 2004

Despite a burgeoning research effort directed at the design and modelling of effective urban spaces for pedestrians, remarkably little is known about how pedestrians actually negotiate urban spaces. This paper reports the results of a video-based observational study aimed at exploring: (1) individuals' movement preferences within uncluttered environments, in particular: (a) desired walking speed, (b) microscopic position preferences, and (c) interpersonal distances between companions while walking; and (2) the ways in which these variables might be influenced by the various personal, situational, and environmental factors that characterise the context in which pedestrians move. The microscopic movement trajectories of 2613 participants were investigated in a covert, video-based observational study of three mixed-use (residential/retail) urban environments close to the city centres of Edinburgh and York, United Kingdom. Age, gender, level of mobility, group size, time of day, and location were found to have significant effects on movement preferences across the range of locations studied. We concluded that a number of influential factors affect how humans negotiate urban spaces, and suggested how these factors may be taken into account in attempts to design and model effective urban spaces for pedestrians.
Planned Conversion of Rural Land: A Case Study of Planning Applications for Housing and Open Storage Uses in Agriculture Zones
Authors: Chau Kwong-Wing , Lai Lawrence Wai-Chung
Published: November 2004

This paper uses 1372 sets of cross-sectional data to evaluate empirically the probit estimates for five hypotheses regarding planning applications for the conversion of leasehold land lying fallow or under active agriculture to nonagricultural uses in agriculture zones in Hong Kong. Though the agriculture zones occupy just 5.6% of all zoned land and the agricultural sector generates 0.1% of GDP and 0.9% of jobs, they attract a disproportionate 17.6% of planning applications. It is established that the Town Planning Board prefers to release development rights to indigenous villagers to construct ‘small houses’ than to container storage operators, though open storage of containers is a derived demand generated by an international container port. However, the fact that the Hong Kong government announced a major housing supply programme in July 1997 has not affected the pattern of decisions for agriculture zones. Indeed, for all nonagricultural use applications, the board has shown a dislike for large-scale development and been particularly more restrictive as regards applications arising in Sai Kung. This discussion is made with reference to the potential contribution of the modelling approach to planning research in general and the rural land-use policies and law of Hong Kong in particular.
Types of Gated Communities
Authors: Grant Jill , Mittelsteadt Lindsey
Published: November 2004

In the last decade the planning literature has reflected growing interest in the topic of gated communities. To date, this relatively new field of research has generated limited theoretical development. Although recent literature has begun to elucidate the social and economic contexts that make gated enclaves a global phenomenon, few works offer an overview of the physical features of gated communities. The key source articulating a framework for understanding gated communities is Blakely and Snyder's, Fortress America. Although Blakely and Snyder provide detailed findings on the form of gated projects in the US context, they say little about gating elsewhere. This paper draws on a range of literature on gated enclaves to examine and augment the typology created by Blakely and Snyder. Building theory to explain the form and character of gated communities requires the consideration of a range of historical experiences and international differences in practice. Although classification alone does not constitute theory, it provides an important foundation for those seeking to generate premises and principles for further theoretical development. It also offers useful tools for case studies of practice.
Dopamine transporters depolarize neurons by a channel mechanism
Authors: Carvelli Lucia , McDonald Paul W. , Blakely Randy D. , DeFelice Louis J.
Published: November 2004

Neurotransmitter transporters generate larger currents than expected if one assumes fixed stoichiometry models. It remains controversial, however, whether these depolarizing currents arise from high density and rapid turnover rates of a classical transporter, or whether transporters exhibit bona fide channel behavior. Although heterologously expressed transporters show single-channel behavior and noise analysis in native cells strongly suggests channel behavior, no directly observed single-channel events associated with transporters have been reported thus far in native cells. We describe single-channel events arising directly from the
Caenorhabditis elegans
dopamine transporter (DAT-1) as evidenced by DA-induced channel activity blocked by a high-affinity DAT-1 inhibitor, increased channel activity in neurons that overexpress DAT-1, and loss of channels in
dat-1
knockout neurons. Our data indicate that authentic transporter channels underlie depolarizing whole-cell currents. Thus, DA transporters not only transport DA but also exhibit a channel mode of conduction that directly modulates membrane potential and neuronal function.
In vivo
dynamics of chromatin-associated complex formation in mammalian nucleotide excision repair
Authors: Moné Martijn J. , Bernas Tytus , Dinant Christoffel , Goedvree Feliks A. , Manders Erik M. M. , Volker Marcel , Houtsmuller Adriaan B. , Hoeijmakers Jan H. J. , Vermeulen Wim , van Driel Roel
Published: November 2004

Chromatin is the substrate for many processes in the cell nucleus, including transcription, replication, and various DNA repair systems, all of which require the formation of multiprotein machineries on the chromatin fiber. We have analyzed the kinetics of
in vivo
assembly of the protein complex that is responsible for nucleotide excision repair (NER) in mammalian cells. Assembly is initiated by UV irradiation of a small area of the cell nucleus, after which the accumulation of GFP-tagged NER proteins in the DNA-damaged area is measured, reflecting the establishment of the dual-incision complex. The dynamic behavior of two NER proteins, ERCC1-XPF and TFIIH, was studied in detail. Results show that the repair complex is assembled with a rate of ≈30 complexes per second and is not diffusion limited. Furthermore, we provide
in vivo
evidence that not only binding of TFIIH, but also its helicase activity, is required for the recruitment of ERCC1-XPF. These studies give quantitative insight into the
de novo
assembly of a chromatin-associated protein complex in living cells.
An acoustic microscopy technique reveals hidden morphological defenses inDaphnia
Authors: Laforsch Christian , Ngwa Wilfred , Grill Wolfgang , Tollrian Ralph
Published: November 2004

Inducible defenses are common strategies for coping with the selective force of predation in heterogeneous environments. In recent years the conspicuous and often dramatic morphological plasticity of several waterflea species of the genusDaphniahave been found to be inducible defenses activated by chemical cues released by predators. However, the exact defensive mechanisms remained mysterious. Because even some minute morphological alterations proved to be protective against predatory invertebrates, it has been suggested that the visible morphological changes are only the tip of the iceberg of the entire protective mechanisms. Here we applied a method of ultrasonic microscopy with vector contrast at 1.2 GHz to probe hidden morphological defenses. We found that induction with predator kairomones increases the stability of the carapace in twoDaphniaspecies up to 350%. This morphological plasticity provides a major advantage for the induced morphs during predation because predatory invertebrates need to crush or puncture the carapace of their prey to consume them. Our ultrastructural analyses revealed that the internal architecture of the carapace ensures maximal rigidity with minimal material investment. Our results uncover hidden morphological plasticity and suggest a reconsideration of former classification systems in defended and undefended genotypes inDaphniaand possibly in other prey organisms as well.
Neuronal Shp2 tyrosine phosphatase controls energy balance and metabolism
Authors: Zhang Eric E. , Chapeau Emilie , Hagihara Kazuki , Feng Gen-Sheng
Published: November 2004

Shp2, a Src homology 2-containing tyrosine phosphatase, has been implicated in a variety of growth factor or cytokine signaling pathways. However, it is conceivable that this enzyme acts predominantly in one pathway versus the others in a cell, depending on the cellular context. To determine the putative functions of Shp2 in the adult brain, we selectively deleted Shp2 in postmitotic forebrain neurons by crossing CaMKIIα-Cre transgenic mice with a conditional Shp2 mutant (Shp2
flox
) strain. Surprisingly, a prominent phenotype of the mutant (CaMKIIα-Cre:Shp2
flox/flox
or CaSKO) mice was the development of early-onset obesity, with increased serum levels of leptin, insulin, glucose, and triglycerides. The mutant mice were not hyperphagic but developed enlarged and steatotic liver. Consistent with previous
in vitro
data, we found that Shp2 down-regulates Jak2/Stat3 (signal transducer and activator of transcription 3) activation by leptin in the hypothalamus. However, Jak2/Stat3 down-regulation is offset by a dominant Shp2 promotion of the leptin-stimulated Erk pathway, leading to induction rather than suppression of leptin resistance upon Shp2 deletion in the brain. Collectively, these results suggest that a primary function of Shp2 in postmitotic forebrain neurons is to control energy balance and metabolism, and that this phosphatase is a critical signaling component of leptin receptor ObRb in the hypothalamus. Shp2 shows potential as a neuronal target for pharmaceutical sensitization of obese patients to leptin action.
Atomic structure of a tryptophan-zipper pentamer
Authors: Liu Jie , Yong Wei , Deng Yiqun , Kallenbach Neville R. , Lu Min
Published: November 2004

Coiled-coil motifs are ubiquitous mediators of specific protein-protein interactions through the formation of interlocking hydrophobic seams between α-helical chains. Residues that form these seams occur at the first (a) and fourth (d) positions of a characteristic 7-aa repeat and are primarily aliphatic. The potential of aromatic residues to promote helix association in a coiled coil was explored by engineering a “Trp-zipper” protein with Trp residues at all 14 a and d positions. The protein forms a discrete, stable, α-helical pentamer in water at physiological pH. Its 1.45-Å crystal structure reveals a parallel, five-stranded coiled coil, a previously uncharacterized type of “knobs-into-holes” packing interaction between interfacial Trp side chains, and an unusual ≈8-Å-diameter axial channel lined with indole rings that is filled with polyethylene glycol 400 and water and sulfate ion molecules. The engineered Trp-zipper pentamer enlarges current views of coiled-coil assembly, molecular recognition, and protein engineering, and may serve as a soluble model for membrane ion channels.
Discriminating males alter sperm production between species
Authors: Aspbury Andrea S. , Gabor Caitlin R.
Published: November 2004

Prezygotic reproductive isolation and its importance in speciation is traditionally approached from the viewpoint of those events that occur before mating. However, recent interest in sperm competition theory has shown that prezygotic isolation can be affected by mechanisms that occur after mating but before fertilization. One neglected aspect of these studies is how the cost of sperm production might play a role in species isolation. We examined differential sperm production in a species whose males are sexually parasitized by a unisexual gynogenetic species. Gynogens are clonal females that require sperm from males of closely related bisexual species to initiate embryogenesis. We tested for differential sperm production by male sailfin mollies (
Poecilia latipinna
) when they were in the presence of either a heterospecific, gynogenetic female (
Poecilia formosa
, Amazon molly) or a conspecific female. We found that previously demonstrated male mate choice for conspecific over heterospecific females also is revealed in sperm production. Males from both an allopatric and a sympatric population produce more sperm when in the presence of a conspecific female than when in the presence of a heterospecific female. We suggest that differential sperm production also could play a role in prezygotic reproductive isolation in bisexual species complexes that occur in sympatry.
Antitumor polyketide biosynthesis by an uncultivated bacterial symbiont of the marine sponge
Theonella swinhoei
Authors: Piel Jörn , Hui Dequan , Wen Gaiping , Butzke Daniel , Platzer Matthias , Fusetani Nobuhiro , Matsunaga Shigeki
Published: November 2004

Bacterial symbionts have long been suspected to be the true producers of many drug candidates isolated from marine invertebrates. Sponges, the most important marine source of biologically active natural products, have been frequently hypothesized to contain compounds of bacterial origin. This symbiont hypothesis, however, remained unproven because of a general inability to cultivate the suspected producers. However, we have recently identified an uncultured
Pseudomonas
sp. symbiont as the most likely producer of the defensive antitumor polyketide pederin in
Paederus fuscipes
beetles by cloning the putative biosynthesis genes. Here we report closely related genes isolated from the highly complex metagenome of the marine sponge
Theonella swinhoei
, which is the source of the onnamides and theopederins, a group of polyketides that structurally resemble pederin. Sequence features of the isolated genes clearly indicate that it belongs to a prokaryotic genome and should be responsible for the biosynthesis of almost the entire portion of the polyketide structure that is correlated with antitumor activity. Besides providing further proof for the role of the related beetle symbiont-derived genes, these findings raise intriguing ecological and evolutionary questions and have important general implications for the sustainable production of otherwise inaccessible marine drugs by using biotechnological strategies.
The axonal attractant Netrin-1 is an angiogenic factor
Authors: Park Kye Won , Crouse Dana , Lee Mark , Karnik Satyajit K. , Sorensen Lise K. , Murphy Kelly J. , Kuo Calvin J. , Li Dean Y.
Published: November 2004

Blood vessels and nerves often follow parallel trajectories, suggesting that distal targets use common cues that induce vascularization and innervation. Netrins are secreted by the floor plate and attract commissural axons toward the midline of the neural tube. Here, we show that Netrin-1 is also a potent vascular mitogen. Netrin-1 stimulates proliferation, induces migration, and promotes adhesion of endothelial cells and vascular smooth muscle cells with a specific activity comparable to vascular endothelial growth factor and platelet-derived growth factor. Our evidence indicates that the netrin receptor, Neogenin, mediates netrin signaling in vascular smooth muscle cells, but suggests that an unidentified receptor mediates the proangiogenic effects of Netrin-1 on endothelial cells. Netrin-1 also stimulates angiogenesis
in vivo
and augments the response to vascular endothelial growth factor. Thus, we demonstrate that Netrin-1 is a secreted neural guidance cue with the unique ability to attract both blood vessels and axons, and suggest that other cues may also function as vascular endothelial growth factors.
Model for anaphase B: Role of three mitotic motors in a switch from poleward flux to spindle elongation
Authors: Brust-Mascher I. , Civelekoglu-Scholey G. , Kwon M. , Mogilner A. , Scholey J. M.
Published: November 2004

It has been proposed that the suppression of poleward flux within interpolar microtubule (ipMT) bundles of
Drosophila
embryonic spindles couples outward forces generated by a sliding filament mechanism to anaphase spindle elongation. Here, we (
i
) propose a molecular mechanism in which the bipolar kinesin KLP61F persistently slides dynamically unstable ipMTs outward, the MT depolymerase KLP10A acts at the poles to convert ipMT sliding to flux, and the chromokinesin KLP3A inhibits the depolymerase to suppress flux, thereby coupling ipMT sliding to spindle elongation; (
ii
) used KLP3A inhibitors to interfere with the coupling process, which revealed an inverse linear relation between the rates of flux and elongation, supporting the proposed mechanism and demonstrating that the suppression of flux controls both the rate and onset of spindle elongation; and (
iii
) developed a mathematical model using force balance and rate equations to describe how motors sliding the highly dynamic ipMTs apart can drive spindle elongation at a steady rate determined by the extent of suppression of flux.
Growth factors essential for self-renewal and expansion of mouse spermatogonial stem cells
Authors: Kubota Hiroshi , Avarbock Mary R. , Brinster Ralph L.
Published: November 2004

Spermatogonial stem cells (SSCs) self-renew and produce large numbers of committed progenitors that are destined to differentiate into spermatozoa throughout life. However, the growth factors essential for self-renewal of SSCs remain unclear. In this study, a serum-free culture system and a transplantation assay for SSCs were used to identify exogenous soluble factors that promote proliferation of SSCs. Mouse pup testis cells were enriched for SSCs by selection with an anti-Thy-1 antibody and cultured on STO (SIM mouse embryo-derived thioguanine and ouabain resistant) feeders in a serum-free defined medium. In the presence of glial cell line-derived neurotrophic factor (GDNF), SSCs from DBA/2J strain mice formed densely packed clumps of cells and continuously proliferated. However, other strains of mice required the addition of soluble GDNF-family receptor α-1 and basic fibroblast growth factor to support replication. The functional transplantation assay proved that the clump-forming cells are indeed SSCs. Thus, GDNF-induced cell signaling plays a central role in SSC self-renewal. The number of SSCs in culture doubled every 5.6 days, and the clump-forming cells strongly expressed Oct-4. Under these conditions, SSCs proliferated over 6 months, reconstituted long-term spermatogenesis after transplantation into recipient testes, and restored fertility to infertile recipients. The identification of exogenous factors that allow continuous proliferation of SSCsin vitroestablishes the foundation to study the basic biology of SSCs and makes possible germ-line modification by sophisticated technologies. Moreover, the ability to recover, culture indefinitely, and transplant SSCs will make the germ-line of individual males available for periods extending beyond a normal lifetime.
Cell-density-dependent regulation of neural precursor cell function
Authors: Limoli Charles L. , Rola Radoslaw , Giedzinski Erich , Mantha Sailaja , Huang Ting-Ting , Fike John R.
Published: November 2004

Stress-induced reductions of neural precursor cells from the subgranular zone of the hippocampal dentate gyrus have been linked to impaired neurogenesis and cognitive dysfunction. Given the importance of redox state in regulating multiple damage-responsive pathways in the CNS, we hypothesize that oxidative stress plays a major role in affecting neurogenesis and subsequent cognitive function after cell injury/depletion. Using anin vitrosystem, we showed that the level of reactive oxygen species (ROS), which depend critically on changes in cell density, were significantly higher in neural precursor cells when compared with other primary and transformed cell lines. ROS were significantly elevated (≈4-fold) under low- (<1 × 104cells per cm2) versus high-density (>1 × 105cells per cm2) conditions. Higher ROS levels found at lower cell densities were associated with elevated proliferation and increased metabolic activity. These ROS were likely a result of altered mitochondrial function that ultimately compromised the growth rate of cells. At high cell densities, intracellular ROS and oxidative damage were reduced in concert with an increased expression of mitochondrial superoxide dismutase 2. Our finding that DNA-damage-induced depletion of neural precursor cells in the subgranular zone of mice also led to increased ROS and altered proliferation validated ourin vitrosystem. Increased ROS and proliferation associated with the reduction of precursor cell numbers bothin vitroandin vivocould be reversed with the antioxidant α-lipoic acid. These data showed that neural precursor cells were predisposed to microenvironmental cues that regulate redox-sensitive pathways to control cellular proliferation after CNS damage.
Identification of hair cycle-associated genes from time-course gene expression profile data by using replicate variance
Authors: Lin Kevin K. , Chudova Darya , Hatfield G. Wesley , Smyth Padhraic , Andersen Bogi
Published: November 2004

The hair-growth cycle is an example of a cyclic process that is well characterized morphologically but understood incompletely at the molecular level. As an initial step in discovering regulators in hair-follicle morphogenesis and cycling, we used DNA microarrays to profile mRNA expression in mouse back skin from eight representative time points. We developed a statistical algorithm to identify the set of genes expressed within skin that are associated specifically with the hair-growth cycle. The methodology takes advantage of higher replicate variance during asynchronous hair cycles in comparison with synchronous cycles. More than one-third of genes with detectable skin expression showed hair-cycle-related changes in expression, suggesting that many more genes may be associated with the hair-growth cycle than have been identified in the literature. By using a probabilistic clustering algorithm for replicated measurements, these genes were grouped into 30 time-course profile clusters, which fall into four major classes. Distinct genetic pathways were characteristic for the different time-course profile clusters, providing insights into the regulation of hair-follicle cycling and suggesting that this approach is useful for identifying hair follicle regulators. In addition to revealing known hair-related genes, we identified genes that were not previously known to be hair cycle-associated and confirmed their temporal and spatial expression patterns during the hair-growth cycle by quantitative real-time PCR andin situhybridization. The same computational approach should be generally useful for identifying genes associated with cyclic processes from complex tissues.
Ferromagnesian postperovskite silicates in the D″ layer of the Earth
Authors: Mao Wendy L. , Shen Guoyin , Prakapenka Vitali B. , Meng Yue , Campbell Andrew J. , Heinz Dion L. , Shu Jinfu , Hemley Russell J. , Mao Ho-kwang
Published: November 2004

Natural olivine with 12 mol % Fe2SiO4and synthetic orthopyroxenes with 20% and 40% FeSiO3were studied beyond the pressure–temperature conditions of the core–mantle boundary. All samples were found to convert entirely or partially into the CaIrO3postperovskite structure, which was recently reported for pure MgSiO3. The incorporation of Fe greatly reduces the pressure needed for the transition and establishes the new phase as the major component of the D″ layer. With the liquid core as an unlimited reservoir of iron, core–mantle reactions could further enrich the iron content in this phase and explain the intriguing seismic signatures observed in the D″ layer.
Identification of viral genomic elements responsible for rabies virus neuroinvasiveness
Authors: Faber Milosz , Pulmanausahakul Rojjanaporn , Nagao Kazuhiko , Prosniak Mikhail , Rice Amy B. , Koprowski Hilary , Schnell Matthias J. , Dietzschold Bernhard
Published: November 2004

Attenuated tissue culture-adapted and natural street rabies virus (RV) strains differ greatly in their neuroinvasiveness. To identify the elements responsible for the ability of an RV to enter the CNS from a peripheral site and to cause lethal neurological disease, we constructed a full-length cDNA clone of silver-haired bat-associated RV (SHBRV) strain 18 and exchanged the genes encoding RV proteins and genomic sequences of this highly neuroinvasive RV strain with those of a highly attenuated nonneuroinvasive RV vaccine strain (SN0). Analysis of the recombinant RV (SB0), which was recovered from SHBRV-18 cDNA, indicated that this RV is phenotypically indistinguishable from WT SHBRV-18. Characterization of the chimeric viruses revealed that in addition to the RV glycoprotein, which plays a predominant role in the ability of an RV to invade the CNS from a peripheral site, viral elements such as the trailer sequence, the RV polymerase, and the pseudogene contribute to RV neuroinvasiveness. Analyses also revealed that neuroinvasiveness of an RV correlates inversely with the time necessary for internalization of RV virions and with the capacity of the virus to grow in neuroblastoma cells.
Haploinsufficiency of delta-like 4 ligand results in embryonic lethality due to major defects in arterial and vascular development
Authors: Gale Nicholas W. , Dominguez Melissa G. , Noguera Irene , Pan Li , Hughes Virginia , Valenzuela David M. , Murphy Andrew J. , Adams Niels C. , Lin Hsin Chieh , Holash Jocelyn , Thurston Gavin , Yancopoulos George D.
Published: November 2004

Vascular development depends on the highly coordinated actions of a variety of angiogenic regulators, most of which apparently act downstream of vascular endothelial growth factor (VEGF). One potential such regulator is delta-like 4 ligand (Dll4), a recently identified partner for the Notch receptors. We generated mice in which the Dll4 gene was replaced with a reporter gene, and found that Dll4 expression is initially restricted to large arteries in the embryo, whereas in adult mice and tumor models, Dll4 is specifically expressed in smaller arteries and microvessels, with a striking break in expression just as capillaries merge into venules. Consistent with these arterial-specific expression patterns, heterozygous deletion of Dll4 resulted in prominent albeit variable defects in arterial development (reminiscent of those in Notch knockouts), including abnormal stenosis and atresia of the aorta, defective arterial branching from the aorta, and even arterial regression, with occasional extension of the defects to the venous circulation; also noted was gross enlargement of the pericardial sac and failure to remodel the yolk sac vasculature. These striking phenotypes resulting from heterozygous deletion of Dll4 indicate that vascular development may be as sensitive to subtle changes in Dll4 dosage as it is to subtle changes in VEGF dosage, because VEGF accounts for the only other example of haploid insufficiency, resulting in obvious vascular abnormalities. In summary, Dll4 appears to be a major trigger of Notch receptor activities previously implicated in arterial and vascular development, and it may represent a new opportunity for pro- and anti-angiogenic therapies.
Convergent evolution of behavior in an adaptive radiation of Hawaiian web-building spiders
Authors: Blackledge Todd A. , Gillespie Rosemary G.
Published: November 2004

Species in ecologically similar habitats often display patterns of divergence that are strikingly comparable, suggesting that natural selection can lead to predictable evolutionary change in communities. However, the relative importance of selection as an agent mediatingin situdiversification, versus dispersal between habitats, cannot be addressed without knowledge of phylogenetic history. We used an adaptive radiation of spiders within the Hawaiian Islands to test the prediction that species of spiders on different islands would independently evolve webs with similar architectures.Tetragnathaspiders are the only nocturnal orb-weaving spiders endemic to the Hawaiian archipelago, and multiple species of orb-weavingTetragnathaco-occur within mesic and wet forest habitats on each of the main islands. Therefore, comparison of web architectures spun by spiders on different islands allowed study of replicated evolutionary events of past behavioral diversification. We found that species within each island construct webs with architectures that differ from one another. However, pairs of species on different islands, “ethotypes,” share remarkable similarities in web architectures. Phylogenetic analysis demonstrated that the species comprising these ethotypes evolved independent of one another. Our study illustrates the high degree of predictability that can be exhibited by the evolutionary diversification of complex behaviors. However, not all web architectures were shared between islands, demonstrating that unique effects also have played an important role in the historical diversification of behavior.
Issues in dietary intake assessment of children and adolescents
Authors: Livingstone M. B. E. , Robson P. J. , Wallace J. M. W.
Published: November 2004

Studies of food habits and dietary intakes face a number of unique respondent and observer considerations at different stages from early childhood to late adolescence. Despite this, intakes have often been reported as if valid, and the interpretation of links between intake and health has been based, often erroneously, on the assumption of validity. However, validation studies of energy intake data have led to the widespread recognition that much of the dietary data on children and adolescents is prone to reporting error, mostly through under-reporting. Reporting error is influenced by body weight status and does not occur systematically across different age groups or different dietary survey techniques. It appears that the available methods for assessing the dietary intakes of children are, at best, able to provide unbiased estimates of energy intake only at the group level, while the food intake data of most adolescents are particularly prone to reporting error at both the group and the individual level. Moreover, evidence for the existence of subject-specific responding in dietary assessments challenges the assumption that repeated measurements of dietary intake will eventually obtain valid data. Only limited progress has been made in understanding the variables associated with misreporting in these age groups, the associated biases in estimating nutrient intakes and the most appropriate way to interpret unrepresentative dietary data. Until these issues are better understood, researchers should exercise considerable caution when evaluating all such data.
Dietary sesame (Sesamum indicum cultivar Linn) oil inhibits iron-induced oxidative stress in rats
Authors: Hemalatha S. , Raghunath M. , Ghafoorunissa
Published: November 2004

The high stability of sesame oil against oxidative deterioration is attributed to lignans in its non-glycerol fraction. The present study evaluates the effects of feeding sesame lignans (sesamin and sesamolin) on Fe2+-induced oxidative stress in rats. Three groups, each of sixteen male weanling WNIN rats, were fed diets containing 200 g casein/kg and 100 g oil/kg (group 1, groundnut oil; group 2, sesame oil; group 3, sesame oil+sesamin (0·4 g/kg). After 45 d of feeding, eight rats from each group were injected with saline (9 g Na Cl/l, controls) intraperitoneally while the remaining eight rats were injected with 30 mg Fe2+/kg body weight as ferrous sulfate in normal saline. The animals were killed after 90 min to evaluate hepatic function and antioxidant status. Compared with those fed groundnut oil (group 1), sesame oil-fed rats (groups 2 and 3) had lower levels of hepatic thiobarbituric acid-reactive substances, serum glutamate:oxaloacetate transaminase activities and serum glutamate pyruvate transaminase activities, indicating protection against Fe-induced oxidative stress. Despite similar tocopherol levels in the three diets, hepatic α-tocopherol levels were higher in rats fed the sesame-oil diets (groups 2 and 3) compared with controls (group 1). However, activities of hepatic antioxidant enzymes (superoxide dismutase and glutathione peroxidase) were significantly (P<0·05) increased only in rats fed higher levels of lignans (group 3). These observations suggest that sesame lignans may have sparing effects on tocopherols. The increased bioavailability of tocopherols in the presence of dietary lignans might be due to the regeneration of oxidized tocopherols. The synergistic effects of lignans with tocols has nutritional and therapeutic implications.
Trends in energy and macronutrient intakes, body weight and physical activity in female university students (1988–2003), and effects of excluding under-reporters
Authors: Warwick Penelope M. , Reid Jacqueline
Published: November 2004

The present study investigated trends in reported energy intake, macronutrient intake, physical activity level (PAL) and body weight and effects of excluding under-reporters (UR). Dietary intake and time spent in sixteen activity categories were recorded by 887 female university students (median age 29 years) from 1988 to 2003. Energy expenditure (EE) and PAL were measured using a factorial method. All data collected were self-reported. Individuals with reported EI:EE<0·76 were classified as UR. The remainder were classified as non-under-reporters (NUR). Trends were determined from simple linear regression of median data for each year for the entire cohort (ALL) and for NUR and UR separately, and from multiple regression analysis with the subgroups (NUR and UR) as an additional predictor (BOTH). Prevalence of under-reporting and overweight increased between 1988 and 2003. In ALL and BOTH there were trends to increased body mass, protein intake (g/d and % energy) and carbohydrate intake (% energy only) and decreased fat and alcohol intakes (g/d and % energy). In BOTH there were also increases in reported EI and carbohydrate intake (g/d). None of the trends in NUR was significantly different from those in UR, but some trends in ALL and/or BOTH were not significant when UR were excluded. Trends remaining significant in NUR were increased reported energy intake, protein (g/d) and carbohydrate (g/d) intakes, and decreased fat (% energy only) intake. There were no significant trends in PAL. We conclude that some, but not all, dietary trends were affected by exclusion of UR.
The use of high-selenium yeast to raise selenium status: how does it measure up?
Authors: Rayman Margaret P.
Published: November 2004

Selenium-enriched yeast (Se-yeast) is a common form of Se used to supplement the dietary intake of this important trace mineral. However, its availability within the European Union is under threat, owing to concerns expressed by the European Community (EC) Scientific Committee on Food that Se-yeast supplements are poorly characterised and could potentially cause the build up of Se in tissues to toxic levels. The present review examines the validity of these concerns. Diagrams of the biosynthesis and metabolism of Se compounds show which species can be expected to occur in Se-yeast preparations. Se-yeast manufacture is described together with quality-control measures applied by reputable manufacturers. The way in which speciation of Se-yeast is achieved is explained and results on amounts of Se species in various commercial products are tabulated. In all cases described, selenomethionine is the largest single species, accounting for 54–74 % of total Se. Se-yeast is capable of increasing the activity of the selenoenzymes and its bioavailability has been found to be higher than that of inorganic Se sources in all but one study. Intervention studies with Se-yeast have shown the benefit of this form in cancer prevention, on the immune response and on HIV infection. Of about one dozen supplementation studies, none has shown evidence of toxicity even up to an intake level of 800 μg Se/d over a period of years. It is concluded that Se-yeast from reputable manufacturers is adequately characterised, of reproducible quality, and that there is no evidence of toxicity even at levels far above the EC tolerable upper intake level of 300 μg/d.
Dose dependency of the effect of ornithine α-ketoglutarate on tissue glutamine concentrations and hypercatabolic response in endotoxaemic rats
Authors: Pernet Pascal , Coudray-Lucas Colette , Schneid Christina , Jardel Alain , Cynober Luc
Published: November 2004

The optimal dosage of ornithine α-ketoglutarate (OKG) for repleting tissue glutamine (Gln) concentrations and maintaining N homeostasis after injury is unknown. We set out to perform ‘dose-ranging’ of OKG supplementation after an endotoxaemic challenge. Sixty-one male Wistar rats were injected with 3 mg lipopolysaccharide (LPS) from Escherichia coli/kg (n 50) or saline vehicle (9 g NaCl/l; controls n 11). After a 24 h fast, survivors were fed by gavage for 48 h with a polymeric standard diet (879 kJ/kg per d and 1·18 g N/kg per d) supplemented with non-essential amino acids (control, n 11; LPS-OKG-0·0, n 9), or with 0·5 g OKG/kg per d (LPS-OKG-0·5, n 12), 1·5 OKG/kg per d (LPS-OKG-1.5, n 11) or 4·5 g OKG/kg per d (LPS-OKG-4·5, n 10). The diets for all groups were made isonitrogenous with the LPS-OKG-4·5 diet by adding an appropriate amount of non-essential amino acids. Rats were killed on day 3 for blood and tissue sampling (muscle, jejunum mucosa, liver). Urine was collected daily for 3-methylhistidine and total N assays. The OKG dose was correlated with Gln concentrations in every tissue and with cumulative N balance (Spearman test, P<0·01). 3-Methylhistidine excretion was increased in endotoxaemic groups compared with controls (ANOVA, P<0·05) except in the LPS-OKG-4·5 group. Only the LPS-OKG-4·5 group achieved a positive post-injury N balance (t test, P<0·05). In conclusion, OKG exerted a dose-dependent effect on tissue Gln concentration and N balance, but only the highest dosage counteracted myofibrillar hypercatabolism and caused a positive N balance.
Effect of garlic (Allium sativum) powder tablets on serum lipids, blood pressure and arterial stiffness in normo-lipidaemic volunteers: a randomised, double-blind, placebo-controlled trial
Authors: Turner Beate , Mølgaard Christian , Marckmann Peter
Published: November 2004

Recent studies have cast doubt on the proposed lipid-lowering and blood pressure-lowering effects of garlic. We tested the effect of dried garlic (Allium sativum) powder on blood lipids, blood pressure and arterial stiffness in a 12-week randomised, double-blind, placebo-controlled trial. Seventy-five healthy, normo-lipidaemic volunteers (men and women aged 40–60 years) were assigned to dried garlic powder tablets (10·8 mg alliin (3-(2-propenylsulfinyl)-l-alanine)/d, corresponding to about three garlic cloves) or placebo. Sixty-two subjects were eligible for the per-protocol analysis. The primary outcome measure was serum total cholesterol concentration. Secondary outcome measures were LDL-cholesterol, HDL-cholesterol and triacylglycerol concentrations, blood pressure and arterial stiffness (assessed by pulse wave velocity). No significant differences between the garlic and placebo groups were detected for any of the outcome measures. However, garlic powder was associated with a near-significant decrease (12 %) in triacylglycerol concentration (P=0·07). In conclusion, garlic powder tablets have no clinically relevant lipid-lowering and blood pressure-lowering effects in middle-aged, normo-lipidaemic individuals. The putative anti-atherosclerotic effect of garlic may be linked to risk markers other than blood lipids.
Assistant nurses in the Swedish healthcare sector during the 1990s: A hard-hit occupational group with a tough job
Authors: Hertting Anna , Nilsson Kerstin , Theorell Töres , Sätterlund Larsson Ullabeth
Published: November 2004

Aims: The aim of the study was to explore hospital-based assistant nurses' experiences of psychosocial ``stressors'', following a period of substantial layoffs (43%) and ongoing healthcare reorganizations. Methods: An interview study was carried out with 11 assistant nurses working in the same hospital. The interviews took place in 1997, in connection with the last round of redundancies, and were followed up in 1998 and then in 2001. Interviews were audiotaped and transcribed; the content was then analysed. Results: Two main themes were identified from the women's perceived stressors: (a) a hard-hit occupational group experiencing ``energy-consuming adjustments'', and a ``weak position'' at the continuing workplace. Job insecurity meant fear of losing valued work tasks in nursing care (de-skilling). The common feature was the duality in the women's descriptions of feeling qualified in nursing care but being treated like a maid, or having intimate practical knowledge but no formal competence; (b) a tougher but underpaid job including ``heavy workload'' concurrent with ``organizational shortcomings'', and ``frozen salary trends'' with a simultaneous feeling of lacking the power to improve their situation. Conclusions: Our results underscore the importance of the employer's attention to the remaining workers in connection with downsizing, particularly when the reduction of the workforce has been as dramatic as in this case. It is also important to understand the ongoing dilemma (strain) for the assistant nurses, who are faced with increasing demands for further formal qualifications in hospital care, while maintaining a strong occupational desire to keep their highly valued job working close to the patient.
Netrins and neogenin promote myotube formation
Authors: Kang Jong-Sun , Yi Min-Jeong , Zhang Wei , Feinleib Jessica L. , Cole Francesca , Krauss Robert S.
Published: November 2004

Differentiation of skeletal myoblasts into multinucleated myotubes is a multistep process orchestrated by several families of transcription factors, including myogenic bHLH and NFAT proteins. The activities of these factors and formation of myotubes are regulated by signal transduction pathways, but few extracellular factors that might initiate such signals have been identified. One exception is a cell surface complex containing promyogenic Ig superfamily members (CDO and BOC) and cadherins. Netrins and their receptors are established regulators of axon guidance, but little is known of their function outside the nervous system. We report here that myoblasts express the secreted factor netrin-3 and its receptor, neogenin. These proteins stimulate myotube formation and enhance myogenic bHLH- and NFAT-dependent transcription. Furthermore, neogenin binds to CDO in a cis fashion, and myoblasts lacking CDO are defective in responding to recombinant netrin. It is proposed that netrin-3 and neogenin may promote myogenic differentiation by an autocrine mechanism as components of a higher order complex of several promyogenic cell surface proteins.