bluuebunny/crossref_metadata_2025 huggingface dataset:
Anchorage of coniferous trees in relation to species, soil type, and rooting depth
Authors: Nicoll Bruce C , Gardiner Barry A , Rayner Bill , Peace Andrew J
Published: July 2006

A database was constructed of tree-anchorage measurements from almost 2000 trees from 12 conifer species that were mechanically overturned on 34 sites in the United Kingdom between 1960 and 2000. Anchorage was compared among species, soil groups (freely-draining mineral, gleyed mineral, peaty mineral, and deep peat) and root depth classes (shallow, <40 cm; medium, 40–80 cm; and deep, >80 cm) using regressions of critical turning moment against stem mass. Sitka spruce (Picea sitchensis (Bong.) Carr.) was used as a benchmark because it formed the largest part of the database and was the only species with all soil-group and depth-class combinations. Anchorage of Sitka spruce was strongest on peat and poorest on gleyed mineral soils. Deep rooting increased critical turning moments by 10%–15% compared with trees of equivalent mass with shallower roots. Significantly better anchorage than Sitka spruce was found for grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), with various rooting depths on freely draining and gleyed mineral soils and for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) on medium-depth mineral soil. Lodgepole pine (Pinus contorta Dougl. ex Loud.) had poorer anchorage than Sitka spruce over a range of soil groups and root depth classes. Norway spruce (Picea abies (L.) Karst.) on shallow gleyed mineral soil, and Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) on medium depth mineral soil, also had poorer anchorage. Other combinations had similar anchorage to the equivalent Sitka spruce. These results are discussed with respect to the development of forest wind-risk models.
A note on fire frequency concepts and definitions
Authors: Reed William J
Published: July 2006

The concepts of hazard of burning, fire interval, and fire cycle are considered. It is claimed that the current notion of fire cycle is poorly defined, since the time required to burn a specified area is a random variable. It is shown that the expected time to burn an area equal in size to the study area normally exceeds the fire interval (the average time between fires at any location). In view of this, it is recommended that the notion of fire cycle in its current form be abandoned.
DAMAGE SPREADING ON A SET OF HIERARCHICAL TRIVALENT STRUCTURES
Authors: GUO Z. Z. , WANG CHUN-AN , WU XIAO-WEI
Published: July 2006

The damage spreading of the Ising model on a set of trivalent structures is studied with competing Glauber and Kawasaki dynamics. We find that the damage transition temperature Td increases as the number of rectangles increases at the pure Glauber dynamics case and Td decreases sharply as the probability of occurrence of Kawasaki dynamics increases. A heuristic argument is provided to explain the numerical results.
INSIGNIFICANT NEXT NEAREST NEIGHBOR EFFECT INNi(II)-[2×2] GRID
Authors: BAYRI ALI
Published: July 2006

The Next Nearest Neighbor (NNN) effect in Ni2+-[2×2] using the isotropic Heisenberg model has been investigated in this article. Although the NNN effect is commonly very weak in this kind of grid, it was calculated that its response is quite big to the outsider perturbations in certain regions. Two different antiferromagnetic arrangements of spins interacting via the Heisenberg exchange type in a square were discussed in terms of their stability regions. Using the isotropic Heisenberg exchange Hamiltonian, the zero field energy spectrum has been calculated for this particular Ni2+-[2×2] grid geometry. The average magnetic moments with and without the next nearest neighbors interactions were also calculated. In order to verify the calculations, the results were compared with experimental data which had been published in literature.
TRIAL SOLUTION AND CRITICAL FREQUENCY TO THE SINGLY QUANTIZED VORTEX IN BIG BOSE–EINSTEIN CONDENSATES
Authors: XU YAN , JIA DUOJE , CHEN ZHAOYANG
Published: July 2006

A novel solution to the singly quantized vortex is presented for big Bose–Einstein condensates in axis-symmetric harmonic traps, which is valid in the regime of strong coupling parameters. This solution manifests the vortex as a topological soliton and describes correctly its global structure for the whole region of large condensates including the vortex-core, except for the thin boundary region. An improved expression for thermodynamical critical rotation frequency for vortex formation is derived based on our solution, conforming to the known frequency formula given by Lundh et al. in the Thomas–Fermi limit.
A COMPARISON OF THE RESISTIVITY BEHAVIOR OF MgB2, AlB2 AND AgB2 SYSTEMS
Authors: LAL R. , AWANA V. P. S. , SINGH K. P. , SAXENA R. B. , KISHAN H. , NARLIKAR A. V.
Published: July 2006

Measurements have been performed on the resistivity of samples MgB 2, AlB 2 and AgB 2. The samples show presence of impurities. By analyzing the data in terms of impurity scattering, electron-phonon scattering, and weak localization, it has been found that the AlB 2 ( AgB 2) sample involves maximum (minimum) effect of the impurity, electron-phonon interaction and weak localization.
ELECTRON PARALLEL COMPRESSIBILITY IN THE NONLINEAR DEVELOPMENT OF TWO-DIMENSIONAL COLLISIONLESS MAGNETOHYDRODYNAMIC RECONNECTION
Authors: DEL SARTO DANIELE , CALIFANO F. , PEGORARO F.
Published: July 2006

Some topological aspects of the magnetic reconnection phenomenon are summarized and recent numerical results, derived within a two-fluid model, of two-dimensional collisionless magnetic reconnection in presence of a strong guide field are reported. Both the Alfvèn and the whistler frequency range are investigated by including electron parallel compressibility effects that are related respectively to thermal effects and to density fluctuations. The Hamiltonian character of the system is emphasized as it drives the small scale dynamics through the presence of topological invariants. These determine the formation and the shape of small scale current and vorticity layers inside the magnetic island. Secondary fluid instabilities, mainly of the Kelvin–Helmholtz type, can destabilize these layers when a hydrodynamic type regime is achieved. The inclusion of parallel electron compressibility has stabilizing effects. In view of the limitations of the two-fluid modelling, possible developments are briefly discussed such as the inclusion of Larmor-radius corrections, in lieu of a fully kinetic approach.
Archaeology and Texts: Subservience or Enlightenment
Authors: Moreland John
Published: July 2006

An overview of the relationship between archaeology and history is presented as the context in which to situate the argument that a rapprochement between the disciplines can be achieved only if we begin to think of texts and objects as having had efficacy in the past rather than just as evidence about it. Discussions of the meaning of material culture and the power of texts conclude with the suggestion that historical archaeologists need to be more cognizant of the latter. A case-study from the Roman world is used to illustrate the fact that texts can be both instruments of oppression and vehicles for enlightenment and liberation.
Archaeology of Overshoot and Collapse
Authors: Tainter Joseph A.
Published: July 2006

The literature on sustainability and the human future emphasizes the belief that population and/or mass consumption caused resource degradation and collapse in earlier societies. Archaeological literature proposing overshoot and collapse appears in current debates over resource conservation versus continued economic growth. The prominence of this debate, with its national and international dimensions, makes it important to assess whether there is evidence in the archaeological literature for overshoot and collapse brought on by Malthusian overpopulation and/or mass consumption.
Local Knowledge and Memory in Biodiversity Conservation
Authors: Nazarea Virginia D.
Published: July 2006

For the past two decades, biodiversity conservation has been an area of concerted action and spirited debate. Given the centrality of biodiversity to the earth's life support system, its increasing vulnerability is being addressed in international conservation as well as in research by anthropologists and other social scientists on the cultural, economic, political, and legal aspects of human engagement with biological resources. The concepts of biodiversity as a social construct and historical discourse, of local knowledge as loaded representation and invented tradition, and of cultural memory as selective reconstruction and collective political consciousness have also been the foci of recent critical reflection.
The Posterior and the Prior in Bayesian Phylogenetics
Authors: Alfaro Michael E. , Holder Mark T.
Published: July 2006

Bayesian analysis has enjoyed explosive growth in phylogenetics over the past five years. Accompanying this popularity has been increased focus on the meaning of the posterior probability (PP) and the role of the prior in phylogenetic inference. Here we discuss the behavior of the PP in Bayesian and frequentist terms and its relationship to parametric and nonparametric bootstrapping. We also review the use of priors in phylogenetics and the issues surrounding the specification of informative and minimally informative prior distributions.
Genetic Analysis of Brain Circuits Underlying Pheromone Signaling
Authors: Dulac C. , Wagner S.
Published: July 2006

Molecular approaches and genetic manipulations have provided novel insights into the processing of pheromone-mediated information by the olfactory and vomeronasal systems of mammals. We will review and discuss the specific contribution of each of the two chemosensory systems that ensure specific behavioral responses to conspecific animals.
Chromatin Insulators
Authors: Valenzuela Lourdes , Kamakaka Rohinton T.
Published: July 2006

Active and silenced chromatin domains are often in close juxtaposition to one another, and enhancer and silencer elements operate over large distances to regulate the genes in these domains. The lack of promiscuity in the function of these elements suggests that active mechanisms exist to restrict their activity. Insulators are DNA elements that restrict the effects of long-range regulatory elements. Studies on different insulators from different organisms have identified common themes in their mode of action. Numerous insulators map to promoters of genes or have binding sites for transcription factors and like active chromatin hubs and silenced loci, insulators also cluster in the nucleus. These results bring into focus potential conserved mechanisms by which these elements might function in the nucleus.
DNA Double-Strand Break Repair: All's Well that Ends Well
Authors: Wyman Claire , Kanaar Roland
Published: July 2006

Breaks in both DNA strands are a particularly dangerous threat to genome stability. At a DNA double-strand break (DSB), potentially lost sequence information cannot be recovered from the same DNA molecule. However, simple repair by joining two broken ends, though inherently error prone, is preferable to leaving ends broken and capable of causing genome rearrangements. To avoid DSB-induced genetic disinformation and disruption of vital processes, such as replication and transcription, cells possess robust mechanisms to repair DSBs. Because all breaks are not created equal, the particular repair mechanism used depends largely on what is possible and needed based on the structure of the broken DNA. We argue that although categorizing different DSB repair mechanisms along pathways and subpathways can be conceptually useful, in cells flexible and reversible interactions among DSB repair factors form a web from which a nonpredetermined path to repair for any number of different DNA breaks will emerge.
Genetics of Egg-Laying in Worms
Authors: Schafer William R.
Published: July 2006

Genetic studies of behavior in the nematode Caenorhabditis elegans have provided an effective approach to investigate the molecular and cellular basis of nervous system function and development. Among the best studied behaviors is egg-laying, the process by which hermaphrodites deposit developing embryos into the environment. Egg-laying involves a simple motor program involving a small network of motorneurons and specialized smooth muscle cells, which is regulated by a variety of sensory stimuli. Analysis of egg-laying–defective mutants has provided insight into a number of conserved processes in nervous system development, including neurogenesis, cell migration, and synaptic patterning, as well as aspects of excitable cell signal transduction and neuromodulation.
Interplay of Circadian Clocks and Metabolic Rhythms
Authors: Wijnen Herman , Young Michael W.
Published: July 2006

This review examines the connections between circadian and metabolic rhythms. Examples from a wide variety of well-studied organisms are used to illustrate some of the genetic and molecular pathways linking circadian timekeeping to metabolism. The principles underlying biological timekeeping by intrinsic circadian clocks are discussed briefly. Genetic and molecular studies have unambiguously identified the importance of gene expression feedback circuits to the generation of overt circadian rhythms. This is illustrated particularly well by the results of genome-wide expression studies, which have uncovered hundreds of clock-controlled genes in cyanobacteria, fungi, plants, and animals. The potential connections between circadian oscillations in gene expression and circadian oscillations in metabolic activity are a major focus of this review.
Networking Goes International: An Update
Authors: Slaughter Anne-Marie , Zaring David
Published: July 2006

▪ Abstract  This literature review asks three questions of the scholarship on the regulatory networks that have so transformed global governance. First, what are these networks good for? We summarize the state of the literature on regulatory races, the fit between networks and the process of globalization, and the crucial role of the revolution in communications in the development of networks, introducing the topics with a brief intellectual history of regulatory network analysis in international relations and international law scholarship. Second, we examine how we can make sure that regulatory networks are good by asking this question: How might necessary and appropriate accountability mechanisms for the networks be constructed? The answers to these questions are at the foundation of a global administrative law, which is itself the subject of a burgeoning scholarly literature. Our third question concerns the way regulatory networks fit into a world where traditional intergovernmental relations and formally constituted international organizations are still important. We conclude by identifying different ways in which networks and international organizations can complement each other and by spotlighting questions for future research.
Economic Contributions to the Understanding of Crime
Authors: Levitt Steven D. , Miles Thomas J.
Published: July 2006

▪ Abstract  The past decade has seen a sharp increase in the application of empirical economic approaches to the study of crime and the criminal justice system. Much of this research has emphasized identifying causal impacts, as opposed to correlations. These studies have generally found that increases in police and greater incarceration lead to reduced crime. The death penalty, as currently used in the United States, does not appear to lower crime. We also review the evidence on three other crime-related debates in which economists have played a central role: racial profiling, concealed weapons laws, and the impact of legalized abortion.
Fieldwork on Law
Authors: Greenhouse Carol J.
Published: July 2006

▪ Abstract  Based on a review of field-based scholarship on law published in English in 2004 and 2005, this review focuses on themes most strongly emergent across the disciplines of law and the social sciences: state regulation of the private sector, rights (individual rights, indigenous rights, and human rights), and security. These developing areas of field research show the impact of neoliberalism on the social fields of law, an impact intensified by the war on terror. They also point to fresh theoretical horizons in relation to issues of identity, hegemony, and the discursivity of state power. Although disciplines retain their distinctive questions and approaches, they reveal common attention to discourse and practice—particularly in relation to critical events in the war on terror and new forms of executive power, especially in the United States. Current literature thus points not only to new terrain for field research on law, but also, correspondingly, to the changing nature of the field itself as a methodological object.
In the Winter of Our Discontent: Law, Anti-Law, and Social Science
Authors: Galanter Marc
Published: July 2006

▪ Abstract  Law and social science took shape as a field of inquiry in the third quarter of the past century, an era of expanding rights and remedies and optimism about the capacity of law, government, and social science to address intractable social problems. It put down vigorous institutional roots in organizations, publications, teaching, and research that enabled it to survive the erosion of the reformist soil that nurtured it and to adapt to a new era in which the prevailing common sense is a jaundiced view that emphasizes the weaknesses, costs, and dangers of law. A significant body of research has rebutted many of the components of the jaundiced view, but with little effect on the prevailing folklore. The legal system's distinctive susceptibility to such misreadings and misrepresentations is aggravated by a late and weak development of empirical knowledge and a lack of credible guardians of its knowledge base.
The Death of Labor Law?
Authors: Estlund Cynthia L.
Published: July 2006

▪ Abstract  This review tells three interlocking tales of decline, each with its respective prognosis for recovery: the declines of labor law scholarship, labor law, and organized labor. The relationship between the latter two and the role that a reformed labor law might play in reviving organized labor are matters of continuing controversy. In the meantime, two developments on the ground suggest a way forward for organized labor, labor law, and labor law scholars. Activist unions have found success with a new organizing model: neutrality and card-check agreements. Elsewhere, antisweatshop activists are developing increasingly sophisticated supplier codes and monitoring schemes to improve labor standards in developing countries. Both strategies, with their basically contractual architecture, exemplify what regulatory scholars are calling new governance. These strategies suggest a potential way around the roadblocks that meet labor law reform proposals and toward more agile and responsive forms of workplace governance.
General-Purpose Detectors for the Large Hadron Collider
Authors: Froidevaux Daniel , Sphicas Paris
Published: July 2006

▪ Abstract  This review describes the two general-purpose experiments, ATLAS and CMS, that have been designed to study proton-proton collisions at 14 TeV, the highest center-of-mass energy ever achieved, at the Large Hadron Collider at CERN in Geneva, Switzerland. These experiments have undergone a long research and development and construction period since 1989 and are now in the middle of a strenuous and exciting integration, installation, and commissioning period. After a brief introduction to the physics context and prospects as perceived today, this review presents an overview of both projects in terms of their global design characteristics. The main features and challenges related to the tracking systems, to the calorimetry, and to the muon spectrometers are described. The various aspects of the trigger and data acquisition systems and of the computing and software are also discussed broadly. Finally, we conclude with the lessons learned during the design and construction years.
Charge Symmetry Breaking and QCD
Authors: Miller Gerald A. , Opper Allena K. , Stephenson Edward J.
Published: July 2006

▪ Abstract  Charge symmetry breaking (CSB) in the strong interaction occurs because of the difference between the masses of the up and down quarks. The use of effective field theories allows us to follow this influence of confined quarks in hadronic and nuclear systems. We review the progress in observing and understanding CSB, with particular attention to the recent successful observations of CSB in measurements involving the production of a single neutral pion, and to the related theoretical progress.
CP Violation and the CKM Matrix
Authors: Höcker Andreas , Ligeti Zoltan
Published: July 2006

▪ Abstract  Our knowledge of quark-flavor physics and CP violation has increased tremendously over the past five years. It is confirmed that the Standard Model correctly describes the dominant parts of the observed CP-violating and flavor-changing phenomena. Not only does CP violation provide some of the most precise constraints on the flavor sector, but several measurements performed at the B-factories achieved much better precision than expected. We review the present status of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and CP violation, recollect the relevant experimental and theoretical inputs, display the results from the global CKM fit, and discuss their implications for the Standard Model and some of its extensions.
The Physics of DAΦNE and KLOE
Authors: Franzini Paolo , Moulson Matthew
Published: July 2006

▪ Abstract  DAΦNE, the Frascati φ factory, has been in operation since 1999. At the center of the physics program is the KLOE experiment, a multipurpose detector with optimizations for tagged and interferometry-based measurements of the neutral kaon system. KLOE has been taking data since 2000 and has helped to explore a wide array of topics in kaon and hadronic physics, including a comprehensive set of measurements to determine the CKM matrix element [Formula: see text], and a measurement of the [Formula: see text] cross section for the determination of the hadronic contribution to the muon anomaly. In addition, the DEAR experiment has measured the X-ray spectrum of kaonic hydrogen, and the FINUDA experiment has conducted its first studies in hypernuclear spectroscopy and a search for [Formula: see text]-nuclear bound states. We review the design, construction, and operation of the DAΦNE facility, with an emphasis on the physics program of the KLOE experiment.
Neutrino Mass and New Physics
Authors: Mohapatra R.N. , Smirnov A.Y.
Published: July 2006

▪ Abstract  We review the present state and future outlook of our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and attempt to throw light onto the flavor problem of quarks and leptons. This review focuses on the see-saw mechanism, which fits into a big picture of particle physics such as supersymmetry and grand unification, providing a unified approach to the flavor problem of quarks and leptons. We argue that, in combination with family symmetries, this may be at the heart of a unified understanding of the flavor puzzle. We also discuss other new physics ideas, such as neutrinos in models with extra dimensions, and possible theoretical implications of sterile neutrinos. We outline some tests for the various schemes.
Calmodulin kinase II inhibition protects against myocardial cell apoptosis in vivo
Authors: Yang Yingbo , Zhu Wei-Zhong , Joiner Mei-ling , Zhang Rong , Oddis Carmine V. , Hou Yue , Yang Jinying , Price Edward E. , Gleaves Linda , Eren Mesut , Ni Gemin , Vaughan Douglas E. , Xiao Rui-Ping , Anderson Mark E.
Published: July 2006

Inhibition of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) or depletion of sarcoplasmic reticulum (SR) Ca2+ stores protects against apoptosis from excessive isoproterenol (Iso) stimulation in cultured ventricular myocytes, suggesting that CaMKII inhibition could be a novel approach to reducing cell death in conditions of increased adrenergic tone, such as myocardial infarction (MI), in vivo. We used mice with genetic myocardial CaMKII inhibition due to transgenic expression of a highly specific CaMKII inhibitory peptide (AC3-I) to test whether CaMKII was important for apoptosis in vivo. A second line of mice expressed a scrambled, inactive form of AC3-I (AC3-C). AC3-C and wild-type (WT) littermates were used as controls. AC3-I mice have reduced SR Ca2+ content and are resistant to Iso- and MI-induced apoptosis compared with AC3-C and WT mice. Phospholamban (PLN) is a target for modulation of SR Ca2+ content by CaMKII. PLN−/− mice have increased susceptibility to Iso-induced apoptosis. Verapamil pretreatment prevented Iso-induced apoptosis in PLN−/− mice, indicating the involvement of a Ca2+-dependent pathway. AC3-I and AC3-C mice were bred into a PLN−/− background. Loss of PLN increased and equalized SR Ca2+ content in AC3-I, AC3-C, and WT mice and abolished the resistance to apoptosis in AC3-I mice after MI. There was a trend ( P = 0.07) for increased Iso-induced apoptosis in AC3-I mice lacking PLN compared with AC3-I mice with PLN. These findings indicate CaMKII is proapoptotic in vivo and suggest that regulation of SR Ca2+ content by PLN contributes to the antiapoptotic mechanism of CaMKII inhibition.
E3-targeted anti-TRPC5 antibody inhibits store-operated calcium entry in freshly isolated pial arterioles
Authors: Xu Shang-Zhong , Boulay Guylain , Flemming Richard , Beech David J.
Published: July 2006

Smooth muscle cells in arterioles have pivotal roles in the determination of blood pressure and distribution of local blood flow. The cells exhibit calcium entry in response to passive store depletion, but the mechanisms and relevance of this phenomenon are poorly understood. Previously, a role for canonical transient receptor potential 1 (TRPC1) was indicated, but heterologous expression studies showed TRPC1 to have poor function in isolation, suggesting a requirement for additional proteins. Here we test the hypothesis that TRPC5 is such an additional protein, because TRPC5 forms heteromultimeric channels with TRPC1, and RNA encoding TRPC5 is present in arterioles. Recordings were from arteriolar fragments freshly isolated from rabbit pial membrane. Ionic current in response to store depletion has properties like that of the TRPC1/TRPC5 heteromultimer, and so the effect of the E3-targeted, externally acting, anti-TRPC5 blocking antibody (T5E3) was explored. T5E3 suppressed calcium entry in store-depleted arterioles but had no effect in the absence of store depletion. T5E3 preadsorbed to its antigenic peptide did not inhibit calcium entry. TRPC6 is commonly detected in smooth muscle and is present in the arterioles, but T5E3 had no effect on TRPC6. The data suggest that calcium entry occurring in response to passive store depletion in smooth muscle cells of arterioles involves TRPC5 as well as TRPC1.
Time course of synergistic interaction between DOCA and salt on blood pressure: roles of vasopressin and hepatic osmoreceptors
Authors: Brooks Virginia L. , Freeman Korrina L. , Qi Yue
Published: July 2006

In DOCA-salt rats, the time course of the synergistic interaction between osmolality and DOCA to produce hypertension is unknown. Therefore, in rats 2 wk after implantation of subcutaneous silicone pellets containing DOCA (65 mg) or no drug (sham), we determined blood pressure (BP) and heart rate (HR) responses, using telemetric pressure transducers, during 2 wk of excess salt ingestion (1% NaCl in drinking water). BP was unaltered in sham rats after increased salt, but in DOCA rats BP increased within 4 h. The initial hypertension of 30–35 mmHg stabilized within 2 days, followed ∼5 days later by a further increment of ∼30 mmHg. HR first decreased during the dark phase; the second phase was linked to an abrupt increase in HR and BP variability and decreased HR variability. Pressor responses to acute intravenous hypertonic saline infusion were doubled in DOCA-treated rats via vasopressin and nonvasopressin mechanisms. Only in DOCA-treated rats, portal vein hypertonic saline infusion increased BP, which was prevented by V1 vasopressin blockade. After 2 wk of DOCA-salt, oral ingestion of water rapidly decreased BP. Intraportal infusion of water did not lower BP in DOCA-salt rats, suggesting that hepatic osmoreceptors were not involved. In summary, the hypertension of DOCA-treated rats consuming excess salt exhibits multiple phases and can be rapidly reversed. Hypertonicity-induced vasopressin and nonvasopressin pressor mechanisms that are augmented by DOCA, and hepatic osmoreceptors may contribute to the initial developmental phase. With time, combined DOCA-salt induces marked changes in the regulation of the autonomic nervous system, which may favor hypertension development.
Time required for the restoration of normal heavy exercise V̇o2 kinetics following prior heavy exercise
Authors: Burnley Mark , Doust Jonathan H. , Jones Andrew M.
Published: July 2006

Prior heavy exercise markedly alters the O2 uptake (V̇o2) response to subsequent heavy exercise. However, the time required for V̇o2 to return to its normal profile following prior heavy exercise is not known. Therefore, we examined the V̇o2 responses to repeated bouts of heavy exercise separated by five different recovery durations. On separate occasions, nine male subjects completed two 6-min bouts of heavy cycle exercise separated by 10, 20, 30, 45, or 60 min of passive recovery. The second-by-second V̇o2 responses were modeled using nonlinear regression. Prior heavy exercise had no effect on the primary V̇o2 time constant (from 25.9 ± 4.7 s to 23.9 ± 8.8 s after 10 min of recovery; P = 0.338), but it increased the primary V̇o2 amplitude (from 2.42 ± 0.39 to 2.53 ± 0.41 l/min after 10 min of recovery; P = 0.001) and reduced the V̇o2 slow component (from 0.44 ± 0.13 to 0.21 ± 0.12 l/min after 10 min of recovery; P < 0.001). The increased primary amplitude was also evident after 20–45 min, but not after 60 min, of recovery. The increase in the primary V̇o2 amplitude was accompanied by an increased baseline blood lactate concentration (to 5.1 ± 1.0 mM after 10 min of recovery; P < 0.001). Baseline blood lactate concentration was still elevated after 20–60 min of recovery. The priming effect of prior heavy exercise on the V̇o2 response persists for at least 45 min, although the mechanism underpinning the effect remains obscure.
Sphingosine Kinase–Dependent Activation of Endothelial Nitric Oxide Synthase by Angiotensin II
Authors: Mulders Arthur C.M. , Hendriks-Balk Mariëlle C. , Mathy Marie-Jeanne , Michel Martin C. , Alewijnse Astrid E. , Peters Stephan L.M.
Published: July 2006

Objective—

In addition to their role in programmed cell death, cell survival, and cell growth, sphingolipid metabolites such as ceramide, sphingosine, and sphingosine-1-phosphate have vasoactive properties. Besides their occurrence in blood, they can also be formed locally in the vascular wall itself in response to external stimuli. This study was performed to investigate whether vasoactive compounds modulate sphingolipid metabolism in the vascular wall and how this might contribute to the vascular responses.

Methods and Results—

In isolated rat carotid arteries, the contractile responses to angiotensin II are enhanced by the sphingosine kinase inhibitor dimethylsphingosine. Endothelium removal or NO synthase inhibition by
N
ω
-nitro-
l
-arginine results in a similar enhancement. Angiotensin II concentration-dependently induces NO production in an endothelial cell line, which can be diminished by dimethylsphingosine. Using immunoblotting and intracellular calcium measurements, we demonstrate that this sphingosine kinase–dependent endothelial NO synthase activation is mediated via both phosphatidylinositol 3-kinase/Akt and calcium-dependent pathways.

Conclusions—

Angiotensin II induces a sphingosine kinase–dependent activation of endothelial NO synthase, which partially counteracts the contractile responses in isolated artery preparations. This pathway may be of importance under pathological circumstances with reduced NO bioavailability. Moreover, a disturbed sphingolipid metabolism in the vascular wall may lead to reduced NO bioavailability and endothelial dysfunction.
99m
Tc-Annexin-V Functional Imaging of Luminal Thrombus Activity in Abdominal Aortic Aneurysms
Authors: Sarda-Mantel Laure , Coutard Michèle , Rouzet François , Raguin Olivier , Vrigneaud Jean-Marc , Hervatin Florence , Martet Geneviève , Touat Ziad , Merlet Pascal , Le Guludec Dominique , Michel Jean-Baptiste
Published: July 2006

Background—

The mural thrombus of abdominal aortic aneurysms (AAA) is involved in aneurysm progression via several interdependent biological processes including platelet activation.
99m
Tc-annexin V (ANX) is a scintigraphic tracer that binds to phosphatidylserine exposed on activated platelets and apoptotic cells. Here, we evaluated the potential of ANX imaging to assess mural thrombus biological activity in an experimental AAA model. The clinical applicability was further tested ex vivo on human samples of excised AAA thrombi.

Methods and Results—

Experimental AAA was created by infusing elastase into infrarenal abdominal aorta in 17 rats, and 6 sham-operated rats were used as controls. Abdominal ANX scintigraphy was performed 2 weeks later followed by quantitative autoradiography and histological studies. Among the 13 rats which developed AAA, 11 displayed intense ANX uptake within AAA by scintigraphy. ANX uptake in the aneurysms on planar and single-photon emission computed tomography (SPECT) imaging was higher than that observed in infrarenal aorta of sham-operated controls (target/background ratio: 5.7±0.9 versus 1.33±0.21;
P
<0.005 for SPECT). Aneurysm-to-background activity ratios obtained by scintigraphy correlated with ANX activity in corresponding autoradiograms (
R
=0.69;
P
<0.02). This activity was located in the thrombus area where activated platelets and polymorphonuclear leukocytes accumulated. Similar patterns were also found in all of the 7 human AAA thrombi harvested during surgery.

Conclusions—

ANX imaging may assess mural thrombus renewal activity linked to permanent flowing blood interface.
Staphylococcus aureus
Adhesion via Spa, ClfA, and SdrCDE to Immobilized Platelets Demonstrates Shear-Dependent Behavior
Authors: Procopio Evagrio George Niraj , Wei Qi , Kyun Shin Pyong , Konstantopoulos Konstantinos , Ross Julia M.
Published: July 2006

Objective—

The objective of this study is to delineate the molecular mechanisms responsible for
Staphylococcus aureus
–platelet adhesion as a function of physiologically relevant wall shear stresses.

Methods and Results—

A parallel plate flow chamber was used to quantify adhesion of wild-type, Spa
−
, ClfA
−
and SdrCDE
−
strains to immobilized platelet layers. In the absence of plasma, adhesion increases with increasing wall shear rate from 100 to 5000 seconds
−1
. The presence of plasma significantly enhances adhesion at all shear levels. Addition of exogenous fibrinogen yields adhesion levels similar to plasma in the lower shear regimes, but has a diminishing effect on potentiating adhesion at higher shear rates. Alternatively, as shear rate increases von Willebrand factor (VWF) plays an increasingly significant role in mediating binding.

Conclusions—

Addition of plasma proteins potentiates
S aureus
–platelet interactions at all shear rates examined. Whereas fibrinogen plays a significant role in all shear regimes, VWF mediation becomes increasingly important as wall shear rate increases. Fibrinogen binding is dependent on bacterial adhesins ClfA and SdrCDE whereas Spa is the dominant receptor for VWF.
Oxidized Phospholipids Alter Vascular Connexin Expression, Phosphorylation, and Heterocellular Communication
Authors: Isakson Brant E. , Kronke Gerhard , Kadl Alexandra , Leitinger Norbert , Duling Brian R.
Published: July 2006

Objective—In endothelial cells (EC) and vascular smooth muscle cells (VSMC) from atherosclerotic mice, connexin (Cx) expression becomes distorted. Lipoprotein-derived phospholipid oxidation products (OxPAPC) play a critical role in atherosclerosis, and we hypothesized that they may act as trigger molecules causing the changes in connexin expression.

Methods and Results—We applied OxPAPC to murine carotid arteries in vivo and vascular cell cocultures. OxPAPC applied to carotids induced an upregulation of both Cx37 and Cx43 in the VSMC. In EC, Cx43 was upregulated and Cx37 was downregulated, whereas Cx40 in EC remained constant. In the vascular cell coculture, OxPAPC caused similar changes in Cx37 and Cx43 but caused a decrease in Cx40 in EC and an elevation of Cx40 in VSMC. In the coculture model, OxPAPC treatment led to the selective disappearance of Cx40 at the myoendothelial junction. Biocytin dye transfer between EC and VSMC coupling was dramatically reduced by OxPAPC. The decrease in dye transfer after OxPAPC treatment was correlated with an increase in tyrosine 265 phosphorylation of Cx43, especially at the in vitro myoendothelial junction.

Conclusions—We conclude that OxPAPC could be responsible for the changes in connexin expression previously reported in atherosclerosis.
Macrophage ABCG1 Deletion Disrupts Lipid Homeostasis in Alveolar Macrophages and Moderately Influences Atherosclerotic Lesion Development in LDL Receptor-Deficient Mice
Authors: Out Ruud , Hoekstra Menno , Hildebrand Reeni B. , Kruit Janine K. , Meurs Illiana , Li Zhaosha , Kuipers Folkert , Van Berkel Theo J.C. , Van Eck Miranda
Published: July 2006

Objective—

ABCG1 has recently been identified as a facilitator of cellular cholesterol and phospholipid efflux to high-density lipoprotein (HDL). Its expression in macrophages is induced during cholesterol uptake in macrophages and by liver X receptor (LXR). The role of macrophage ABCG1 in atherosclerotic lesion development is, however, still unknown.

Methods and Results—

To assess the role of macrophage ABCG1 in atherosclerosis, we generated low-density lipoprotein (LDL) receptor knockout (LDLr
−/−
) mice that are selectively deficient in macrophage ABCG1 by using bone marrow transfer (ABCG1
−/−
→ LDLr
−/−
). Peritoneal macrophages isolated from donor ABCG1
−/−
mice exhibited a 22% (
P
=0.0007) decrease in cholesterol efflux to HDL. To induce atherosclerosis, transplanted mice were fed a high-cholesterol diet containing 0.25% cholesterol and 15% fat for 6 and 12 weeks. Serum lipid levels and lipoprotein profiles did not differ significantly between ABCG1
−/−
→ LDLr
−/−
mice and controls. In lungs of ABCG1
−/−
→ LDLr
−/−
mice a striking accumulation of lipids was observed in macrophages localized to the subpleural region. After 6 weeks of high-cholesterol diet feeding the atherosclerotic lesion size was 49±12×10
3
μm
2
for ABCG1
+/+
→ LDLr
−/−
mice versus 65±15×10
3
μm
2
for ABCG1
−/−
→ LDLr
−/−
mice and after 12 weeks of high-cholesterol diet feeding 124±17×10
3
μm
2
for ABCG1
+/+
→ LDLr
−/−
mice versus 168±17×10
3
μm
2
for ABCG1
−/−
→ LDLr
−/−
mice. Atherosclerotic lesion size depended on both time and the macrophage ABCG1 genotype (
P
=0.038 by 2-way ANOVA, n≥8), indicating a moderately 33% to 36% increase in lesion formation in the absence of macrophage ABCG1.

Conclusions—

Macrophage ABCG1 deficiency does lead to heavy lipid accumulation in macrophages of the lung, and also a moderately significant effect on atherosclerotic lesion development was observed.
Regulation of Murine Cardiac 20S Proteasomes
Authors: Zong Chenggong , Gomes Aldrin V. , Drews Oliver , Li Xiaohai , Young Glen W. , Berhane Beniam , Qiao Xin , French Samuel W. , Bardag-Gorce Fawzia , Ping Peipei
Published: July 2006

Our recent studies have provided a proteomic blueprint of the 26S proteasome complexes in the heart, among which 20S proteasomes were found to contain cylinder-shaped structures consisting of both α and β subunits. These proteasomes exhibit a number of features unique to the myocardium, including striking differences in post-translational modifications (PTMs) of individual subunits and novel PTMs that have not been previously reported. To date, mechanisms contributing to the regulation of this myocardial proteolytic core system remain largely undefined; in particular, little is known regarding PTM-dependent regulation of cardiac proteasomes. In this investigation, we seek to elucidate the function and regulation of 20S proteasome complexes in the heart. Functionally viable murine cardiac 20S proteasomes were purified. Tandem mass spectrometry analyses, combined with native gel electrophoresis, immunoprecipitation, and immunoblotting, revealed the identification of 2 previously unrecognized functional partners in the endogenous intact cardiac 20S complexes: protein phosphatase 2A (PP2A), and protein kinase A (PKA). Furthermore, our results demonstrated that PP2A and PKA profoundly impact the proteolytic function of 20S proteasomes: phosphorylation of 20S complexes enhances the peptidase activity of individual subunits in a substrate-specific fashion. Moreover, inhibition of PP2A or the addition of PKA significantly modified both the serine- and threonine-phosphorylation profile of proteasomes; multiple individual subunits of 20S (eg, α1 and β2) were targets of PP2A and PKA. Taken together, these studies provide the first demonstration that the function of cardiac 20S proteasomes is modulated by associating partners and that phosphorylation may serve as a key mechanism for regulation.
Cardiac Sodium Channel Na
v
1.5 Is Regulated by a Multiprotein Complex Composed of Syntrophins and Dystrophin
Authors: Gavillet Bruno , Rougier Jean-Sébastien , Domenighetti Andrea A. , Behar Romina , Boixel Christophe , Ruchat Patrick , Lehr Hans-Anton , Pedrazzini Thierry , Abriel Hugues
Published: July 2006

The cardiac sodium channel Na
v
1.5 plays a key role in cardiac excitability and conduction. The purpose of this study was to elucidate the role of the PDZ domain-binding motif formed by the last three residues (Ser-Ile-Val) of the Na
v
1.5 C-terminus. Pull-down experiments were performed using Na
v
1.5 C-terminus fusion proteins and human or mouse heart protein extracts, combined with mass spectrometry analysis. These experiments revealed that the C-terminus associates with dystrophin, and that this interaction was mediated by alpha- and beta-syntrophin proteins. Truncation of the PDZ domain-binding motif abolished the interaction. We used dystrophin-deficient mdx

5cv

mice to study the role of this protein complex in Na
v
1.5 function. Western blot experiments revealed a 50% decrease in the Na
v
1.5 protein levels in mdx

5cv

hearts, whereas Na
v
1.5 mRNA levels were unchanged. Patch-clamp experiments showed a 29% decrease of sodium current in isolated mdx

5cv

cardiomyocytes. Finally, ECG measurements of the mdx

5cv

mice exhibited a 19% reduction in the P wave amplitude, and an 18% increase of the QRS complex duration, compared with controls. These results indicate that the dystrophin protein complex is required for the proper expression and function of Na
v
1.5. In the absence of dystrophin, decreased sodium current may explain the alterations in cardiac conduction observed in patients with dystrophinopathies.
Neural Correlates of Self-distraction from Anxiety and a Process Model of Cognitive Emotion Regulation
Authors: Kalisch Raffael , Wiech Katja , Herrmann Katrin , Dolan Raymond J.
Published: July 2006

Cognitive strategies used in volitional emotion regulation include self-distraction and reappraisal (reinterpretation). There is debate as to what the psychological and neurobiological mechanisms underlying these strategies are. For example, it is unclear whether self-distraction and reappraisal, although distinct at a phenomenological level, are also mediated by distinct neural processes. This is partly because imaging studies on reappraisal and self-distraction have been performed in different emotional contexts and are difficult to compare. We have therefore investigated the neural correlates of self-distraction, as indexed by a thought suppression task, in an anticipatory anxiety paradigm previously employed by us to study reappraisal. Brain activity was measured by functional magnetic resonance imaging. We show that self-distraction recruits the left lateral prefrontal cortex. Based on a review of the existing data, we develop a process model of cognitive emotion regulation. The model posits that both self-distraction and reappraisal attenuate emotional reactions through replacement of emotional by neutral mental contents but achieve replacement in different ways. This is associated with a dependence of self-distraction on a left prefrontal production function, whereas reappraisal depends on a right prefrontal higher order monitoring process.
First- and Second-language Phonological Representations in the Mental Lexicon
Authors: Sebastian-Gallés Núria , Rodríguez-Fornells Antoni , de Diego-Balaguer Ruth , Díaz Begoña
Published: July 2006

Performance-based studies on the psychological nature of linguistic competence can conceal significant differences in the brain processes that underlie native versus nonnative knowledge of language. Here we report results from the brain activity of very proficient early bilinguals making a lexical decision task that illustrates this point. Two groups of Spanish-Catalan early bilinguals (Spanish-dominant and Catalan-dominant) were asked to decide whether a given form was a Catalan word or not. The nonwords were based on real words, with one vowel changed. In the experimental stimuli, the vowel change involved a Catalan-specific contrast that previous research had shown to be difficult for Spanish natives to perceive. In the control stimuli, the vowel switch involved contrasts common to Spanish and Catalan. The results indicated that the groups of bilinguals did not differ in their behavioral and event-related brain potential measurements for the control stimuli; both groups made very few errors and showed a larger N400 component for control nonwords than for control words. However, significant differences were observed for the experimental stimuli across groups: Specifically, Spanish-dominant bilinguals showed great difficulty in rejecting experimental nonwords. Indeed, these participants not only showed very high error rates for these stimuli, but also did not show an error-related negativity effect in their erroneous nonword decisions. However, both groups of bilinguals showed a larger correct-related negativity when making correct decisions about the experimental nonwords. The results suggest that although some aspects of a second language system may show a remarkable lack of plasticity (like the acquisition of some foreign contrasts), first-language representations seem to be more dynamic in their capacity of adapting and incorporating new information.