bluuebunny/crossref_metadata_2025 huggingface dataset:
Triple-Bond Reactivity of Diphosphorus Molecules
Authors: Piro Nicholas A. , Figueroa Joshua S. , McKellar Jessica T. , Cummins Christopher C.
Published: August 2006

We report a mild method for generating the diphosphorus molecule or its synthetic equivalent in homogeneous solution; the P
2
allotrope of the element phosphorus is normally obtained only under extreme conditions (for example, from P
4
at 1100 kelvin). Diphosphorus is extruded from a niobium complex designed for this purpose and can be trapped efficiently by two equivalents of an organic diene to produce an organodiphosphorus compound. Diphosphorus stabilized by coordination to tungsten pentacarbonyl can be generated similarly at 25°C, and in this stabilized form it still efficiently consumes two organic diene molecules for every diphosphorus unit.
Corridors Increase Plant Species Richness at Large Scales
Authors: Damschen Ellen I. , Haddad Nick M. , Orrock John L. , Tewksbury Joshua J. , Levey Douglas J.
Published: August 2006

Habitat fragmentation is one of the largest threats to biodiversity. Landscape corridors, which are hypothesized to reduce the negative consequences of fragmentation, have become common features of ecological management plans worldwide. Despite their popularity, there is little evidence documenting the effectiveness of corridors in preserving biodiversity at large scales. Using a large-scale replicated experiment, we showed that habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species. Our results support the use of corridors in biodiversity conservation.
Heating Up the Hotspot Debates
Authors: Tackley Paul
Published: August 2006

Plates, Plumes, and Paradigms
.
Gillian R. Foulger, James H. Natland, Dean C. Presnall, and Don L. Anderson, Eds.
. Geological Society of America, Boulder, CO, 2005. 893 pp. Paper, $180. ISBN 0-8137-2388-4. Special Paper 388.

Exploring the development, current state, and future prospects of research on hotspot volcanism, the contributors argue for the abandonment of the plume hypothesis.
Coherent Control of Retinal Isomerization in Bacteriorhodopsin
Authors: Prokhorenko Valentyn I. , Nagy Andrea M. , Waschuk Stephen A. , Brown Leonid S. , Birge Robert R. , Miller R. J. Dwayne
Published: August 2006

Optical control of the primary step of photoisomerization of the retinal molecule in bacteriorhodopsin from the all-trans to the 13-cis state was demonstrated under weak field conditions (where only 1 of 300 retinal molecules absorbs a photon during the excitation cycle) that are relevant to understanding biological processes. By modulating the phases and amplitudes of the spectral components in the photoexcitation pulse, we showed that the absolute quantity of 13-cis retinal formed upon excitation can be enhanced or suppressed by ±20% of the yield observed using a short transform-limited pulse having the same actinic energy. The shaped pulses were shown to be phase-sensitive at intensities too low to access different higher electronic states, and so these pulses apparently steer the isomerization through constructive and destructive interference effects, a mechanism supported by observed signatures of vibrational coherence. These results show that the wave properties of matter can be observed and even manipulated in a system as large and complex as a protein.
Comment on "A Well-Preserved
Archaeopteryx
Specimen with Theropod Features"
Authors: Corfe Ian J. , Butler Richard J.
Published: August 2006

On the basis of new information from the 10th specimen of
Archaeopteryx
, Mayr
et al
. (Reports, 2 December 2005, p. 1483) suggested that birds, or avian flight, originated twice. We investigate the statistical support for this phylogenetic hypothesis and show that it is no better supported by available morphological character data than the hypothesis of a single avian origin.
Global Genetic Change Tracks Global Climate Warming in
Drosophila subobscura
Authors: Balanyá Joan , Oller Josep M. , Huey Raymond B. , Gilchrist George W. , Serra Luis
Published: August 2006

Comparisons of recent with historical samples of chromosome inversion frequencies provide opportunities to determine whether genetic change is tracking climate change in natural populations. We determined the magnitude and direction of shifts over time (24 years between samples on average) in chromosome inversion frequencies and in ambient temperature for populations of the fly
Drosophila subobscura
on three continents. In 22 of 26 populations, climates warmed over the intervals, and genotypes characteristic of low latitudes (warm climates) increased in frequency in 21 of those 22 populations. Thus, genetic change in this fly is tracking climate warming and is doing so globally.
Structural Asymmetry of AcrB Trimer Suggests a Peristaltic Pump Mechanism
Authors: Seeger Markus A. , Schiefner André , Eicher Thomas , Verrey François , Diederichs Kay , Pos Klaas M.
Published: August 2006

The AcrA/AcrB/TolC complex spans the inner and outer membranes of
Escherichia coli
and serves as its major drug-resistance pump. Driven by the proton motive force, it mediates the efflux of bile salts, detergents, organic solvents, and many structurally unrelated antibiotics. Here, we report a crystallographic structure of trimeric AcrB determined at 2.9 and 3.0 angstrom resolution in space groups that allow asymmetry of the monomers. This structure reveals three different monomer conformations representing consecutive states in a transport cycle. The structural data imply an alternating access mechanism and a novel peristaltic mode of drug transport by this type of transporter.
Charting Earth's Activities
Authors: Crowley Peter
Published: August 2006

This Dynamic Planet
. World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics.
By Tom Simkin, Robert I. Tilling, Peter R. Vogt, Stephen H. Kirby, Paul Kimberly, and David B. Stewart
. U.S. Geological Survey, Smithsonian Institution, and U.S. Naval Research Laboratory, Washington, DC, 2006. $14. U.S.G.S. Geologic Investigations Series Map I-2800.
www.minerals.si.edu/tdpmap/index.htm

The 1:30 million map and accompanying Web site are intended to provide students, researchers, and the interested public with an overview of Earth's dynamic crust.
Implementation of human papillomavirus testing in cervical screening without a concomitant decrease in participation rate
Authors: Bulkmans N W J , Bulk S , Ottevanger M S , Rozendaal L , Hellenberg S M , van Kemenade F J , Snijders P J F , Boeke A J P , Meijer C J L M
Published: August 2006

Adding high-risk human papillomavirus (hrHPV) testing to screening increases the efficacy of cervical screening programmes. However, hrHPV testing may result in a lower participation rate because of the perceived association with sexually transmitted infections. We describe how testing for hrHPV was added to cervical screening in the POpulation-BAsed SCreening study AMsterdam (POBASCAM) trial. Participation rates of the screening programme before and after hrHPV implementation were evaluated in the region where the POBASCAM trial was carried out. The participation rate was 58.7% before and 61.4% after the addition of hrHPV testing to screening (p<0.001). An inventory of frequently asked questions is presented. Thus, hrHPV testing can be added to cervical screening by cytology without a decrease in participation rate.
Duodenal carcinoma in MUTYH-associated polyposis
Authors: Nielsen M , Poley J W , Verhoef S , van Puijenbroek M , Weiss M M , Burger G T , Dommering C J , Vasen H F A , Kuipers E J , Wagner A , Morreau H , Hes F J
Published: August 2006

Bi-allelic germline mutations in the MUTYH gene give rise to multiple adenomas and an increased incidence of colorectal cancer. In addition, duodenal adenomas and other extra-colonic manifestations have been described in MUTYH-associated polyposis (MAP) patients. We describe two patients with bi-allelic MUTYH gene mutations with duodenal carcinoma. The tumour in Patient A was detected during evaluation of non-specific abdominal complaints. Patient B was already diagnosed with tens of adenomas and a colon carcinoma, when a duodenal neoplasm was detected. The identification of somatic G>T mutations in codon 12 of the K-RAS2 gene provides evidence that the duodenal lesions were induced by MUTYH deficiency. Studies in larger series of MAP patients are needed to investigate the risk of upper-gastro-intestinal malignancies and to determine further guidelines for endoscopical surveillance.
The dangers of dog bites
Authors: Wareham David W , Michael Joy S , Warwick Simon , Whitlock Paul , Wood Alan , Das Satya S
Published: August 2006

This report describes an unusual case of endocarditis caused byCapnocytophaga canimorsusas a result of dog bite. The diagnosis could be established only by molecular techniques after amplification of bacterial DNA from the infected cardiac valve. The epidemiology and management ofCapnocytophagainfections is discussed, as well as the role of prophylactic antibiotics in preventing these infections after dog bites.
NOISE-INDUCED OSCILLATIONS AND THEIR CONTROL IN SEMICONDUCTOR SUPERLATTICES
Authors: HIZANIDIS J. , BALANOV A. G. , AMANN A. , SCHÖLL E.
Published: August 2006

We consider noise-induced charge density dynamics in a semiconductor superlattice. The parameters are fixed in the regime below the Hopf bifurcation that gives birth to spatio-temporal oscillations, where in the absence of noise of the system rests at a fixed point. It is shown that in this case noise can induce in the superlattice quite coherent oscillations of the current through the device. While the regularity of these oscillations depends on the noise intensity, their dominant frequency remains almost constant with variation of the noise level in the system. Further, we demonstrate that a time-delayed feedback scheme that was previously used to control purely temporal oscillations induced by noise, can not only enhance or deteriorate the regularity of stochastic spatio-temporal patterns but also allow for the manipulation of the system's time scales with varying time delay.
NONLINEAR EXCITATIONS IN STRONGLY-COUPLED PLASMA LATTICES: ENVELOPE SOLITONS, KINKS AND INTRINSIC LOCALIZED MODES
Authors: KOURAKIS IOANNIS , SHUKLA PADMA KANT
Published: August 2006

Ensembles of charged particles (plasmas) are a highly complex form of matter, most often modeled as a many-body system characterized by weak inter-particle interactions (electrostatic coupling). However, strongly-coupled plasma configurations have recently been produced in laboratory, either by creating ultra-cold plasmas confined in a trap or by manipulating dusty plasmas in discharge experiments. In this paper, the nonlinear aspects involved in the motion of charged dust grains in a one-dimensional plasma monolayer (crystal) are discussed. Different types of collective excitations are reviewed, and characteristics and conditions for their occurrence in dusty plasma crystals are discussed, in a quasi-continuum approximation. Dust crystals are shown to support nonlinear kink-shaped supersonic solitary longitudinal excitations, as well as modulated envelope localized modes associated with longitudinal and transverse vibrations. Furthermore, the possibility for intrinsic localized modes (ILMs) — Discrete Breathers (DBs) — to occur is investigated, from first principles. The effect of mode-coupling is also briefly considered. The relation to previous results on atomic chains, and also to experimental results on strongly-coupled dust layers in gas discharge plasmas, is briefly discussed.
LOCALIZED MODES IN A CIRCULAR ARRAY OF COUPLED NONLINEAR OPTICAL WAVEGUIDES
Authors: HIZANIDIS K. , DROULIAS S. , TSOPELAS I. , EFREMIDIS N. K. , CHRISTODOULIDES D. N.
Published: August 2006

A circular array of optical waveguides collectively coupled with a central core is investigated. Nonlinear losses, both linear and nonlinear coupling as well as energy transfer between neighboring array elements and between the array and the core are allowed. The concept is ideal for the design of high power stable amplifiers as well as of all-optical data processing devices in optical communications. The existence of stable steady-state continuous wave modes as well as of localized solitary and breathing type modes is demonstrated. These properties render the proposed system functionally rich, far more controllable than a planar one and easier to stabilize.
ATTRACTORS IN CONSERVATIVE SYSTEMS
Authors: CONTOPOULOS G.
Published: August 2006

Normally, conservative systems do not have attractors. However, in a system with escapes, the infinity acts as an attractor. Furthermore, attractors may appear as singularities at a finite distance. We consider the basins of escape in a particular Hamiltonian system with escapes and the rates of escape for various values of the parameters. Then we consider the basins of attraction of a system of two fixed black holes, with particular emphasis on the asymptotic curves of its unstable periodic orbits.
A STABILITY CRITERION FOR MULTIBREATHERS IN KLEIN–GORDON CHAINS
Authors: KOUKOULOYANNIS VASSILIS , ICHTIAROGLOU SIMOS
Published: August 2006

In the present article we present general linear stability criteria for multibreathers in Klein–Gordon chains at low coupling. Our method is constructive, which means that provided a specific potential the method provides the allowed multibreathers and their characteristic exponent to leading order of approximation.
CHAOTIC MICROLASERS BASED ON DYNAMICAL LOCALIZATION
Authors: CAO H. , FANG W. , PODOLSKIY V. A. , NARIMANOV E. E.
Published: August 2006

We report the first direct observation of lasing action from a dynamically localized mode in a microdisk resonator with rough boundary. In contrast to microlasers based on stable ray trajectories, the performance of our device is robust with respect to the boundary roughness and corresponding ray chaos, taking advantage of Anderson localization in angular momentum. The resonator design, although demonstrated here in GaAs-InAs microdisk laser, should be applicable to any lasers and sensors based on semiconductor or polymer materials.
AUTOCORRELATION FUNCTIONS AND FORM FACTORS OF STATISTICALLY INDEPENDENT SUPERPOSITION OF SPECTRAL SEQUENCES
Authors: ROBNIK MARKO
Published: August 2006

First I derive the power spectrum (of the cumulative or integrated level density) for the regular (Poissonian) energy spectrum which is 1/t2, and for the fully chaotic one, which is 1/t, as was observed numerically by Relano et al. [2002], and recently discussed independently by Faleiro et al. [2004]. The statement refers to small values of t ≤ 1, i.e. for times smaller than Heisenberg time. For t ≫ 1 it is always 1/t2. Then I analyze the autocorrelation function for spectrum which is a superposition of statistically independent spectral sequences and derive the exact additivity formula for the autocorrelation function, and consequently for the form factor of the density of energy levels and of the cumulative (integrated) density of energy levels (the form factor is the Fourier transform of the corresponding autocorrelation function). Therefore this theory provides prediction for the deep semiclassical regime of sufficiently small effective Planck constant ℏ eff . However, in not sufficiently deep semiclassical regime (not sufficiently small ℏ eff ) we see a deviation from this behavior, as recently demonstrated numerically by Gomez et al. [2004] in a billiard system [Robnik, 1983] where a power law behavior 1/tα is found, and the exponent α goes continuously from 2 to 1, as the system's dynamics goes from complete integrability (Poisson) to full chaoticity (GOE and GUE), respectively.
BIFURCATIONS IN A PREDATOR-PREY MODEL WITH DIFFUSION AND MEMORY
Authors: ALY SHABAN
Published: August 2006

In this paper we formulate a delayed predator-prey system in two patches in which the per capita migration rate of each species is influenced only by its own density, i.e. there is no response to the density of the other and the growth rate of the predator depends on the prey that was available in the past. If the equilibrium point lies in the Allée effect zone and when the diffusion is present only, we show that at a critical value of the bifurcation parameter the system undergoes a Turing bifurcation, patterns emerge, the spatially homogeneous equilibrium loses its stability and two new spatially non-constant stable equilibria emerge which are asymptotically stable. When the delay is present only, the increase of delay destabilizes the system and causes the occurrence of periodic oscillations, Andronov–Hopf bifurcation. For the full general model (with both diffusion and delay) if the bifurcation parameters are increased through critical values of diffusion and delay the two new spatially nonconstant stationary solutions lose their stability by Hopf bifurcation.
NOISE ESTIMATION BY USE OF NEIGHBORING DISTANCES IN TAKENS SPACE AND ITS APPLICATIONS TO STOCK MARKET DATA
Authors: URBANOWICZ KRZYSZTOF , HOŁYST JANUSZ A.
Published: August 2006

We present a method that uses distances between nearest neighbors in Takens space to evaluate a level of noise. The method is valid even for high noise levels. The method has been verified by estimation of noise levels in several chaotic systems. We have analyzed the noise level for Dow Jones and DAX indexes and we have found that the noise level ranges from 25 to 80% of the signal variance.
Regulation of Mammalian Ciliary Beating
Authors: Salathe Matthias
Published: August 2006

Recent advances in our understanding of the structure-function relationship of motile cilia with the 9 + 2 microtubular arrangement have helped explain some of the mechanisms of ciliary beat regulation by intracellular second messengers. These second messengers include cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) as well as calcium and pH. cAMP activates protein kinase A (PKA), which is localized to the axoneme. The cAMP-dependent phosphorylation of PKA's main target, originally described as p29 in Paramecium, seems to increase ciliary beat frequency (CBF) directly. The mechanism by which cGMP increases CBF is less well defined but involves protein kinase G and possibly PKA. Protein kinase C inhibits ciliary beating. The regulation mechanisms of CBF by calcium remain somewhat controversial, favoring an immediate, direct action of calcium on ciliary beating and a second cyclic nucleotide–dependent phase. Finally, intracellular pH likely affects CBF through direct influences on dynein arms.
Hydrogen peroxide induces S1P1 receptors and sensitizes vascular endothelial cells to sphingosine 1-phosphate, a platelet-derived lipid mediator
Authors: Igarashi Junsuke , Miyoshi Megumi , Hashimoto Takeshi , Kubota Yasuo , Kosaka Hiroaki
Published: August 2006

Sphingosine 1-phosphate (S1P) is a platelet-derived angiogenic lipid growth factor, modulating G-protein-coupled S1P1 receptors (S1P1-R) to activate endothelial nitric oxide synthase (eNOS), as well as MAPK pathways in endothelial cells. We explored whether and how hydrogen peroxide (H2O2), a representative reactive oxygen species, alters S1P1-R expression and influences S1P signaling in cultured bovine aortic endothelial cells (BAECs). When BAECs are treated with pathophysiologically relevant concentrations of H2O2 (150 μM for 30 min), S1P1-R protein expression levels are acutely augmented by ∼30-fold in a dose-dependent fashion. When BAECs have been pretreated with H2O2, subsequent S1P stimulation (100 nM) leads to a higher degree of eNOS enzyme activation (assessed as intracellular cGMP content, 1.7 ± 0.2-fold vs. no H2O2 pretreatment groups, P < 0.05), associated with a higher magnitude of phosphorylation responses of eNOS and MAPK ERK1/2. PP2, an inhibitor of Src-family tyrosine kinase, abolished the effects of H2O2 on both S1P1-R protein upregulation and enhanced BAEC responses to S1P. H2O2 does not augment S1P1 mRNA expression, whereas VEGF under identical cultures leads to increases in S1P1 mRNA signals. Whereas H2O2 attenuates proliferation of BAECs, addition of S1P restores growth responses of these cells. These results demonstrate that extracellularly administered H2O2 increases S1P1-R expression and promotes endothelial responses for subsequent S1P treatment. These results may identify potentially important points of cross-talk between reactive oxygen species and sphingolipid pathways in vascular responses.
Calcium-independent phospholipase A2-catalyzed plasmalogen hydrolysis in hypoxic human coronary artery endothelial cells
Authors: Meyer Maureen C. , McHowat Jane
Published: August 2006

Thrombin stimulation of human coronary artery endothelial cells (HCAEC) results in activation of a membrane-associated, calcium-independent phospholipase A2 (iPLA2) that selectively hydrolyzes membrane plasmalogen phospholipids. Rupture of an atherosclerotic plaque and occlusion of the coronary vasculature results in a coronary ischemic event in which HCAEC in the ischemic area would be exposed to dramatic decreases in oxygen tension in addition to thrombin exposure. We exposed HCAEC to hypoxia in the presence or absence of thrombin stimulation and measured iPLA2 activation, membrane phospholipid hydrolysis, and the accumulation of biologically active phospholipid metabolites. HCAEC exposed to hypoxia, thrombin stimulation, or a combination of the two conditions demonstrated an increase in iPLA2 activity and an increase in arachidonic acid release from plasmenylcholine. Thrombin stimulation of normoxic HCAEC did not result in an accumulation of choline lysophospholipids, but hypoxia alone and in combination with thrombin stimulation led to a significant accumulation of lysoplasmenylcholine (LPlsCho). We propose that the presence of hypoxia inhibits LPlsCho catabolism, at least in part, as a result of the accumulation of long-chain acylcarnitines. The combination of increased production and decreased catabolism of LPlsCho is necessary for its accumulation. Pretreatment with bromoenol lactone to inhibit iPLA2 blocked membrane phospholipid hydrolysis and production of membrane phospholipid-derived metabolites. The increase in iPLA2 activity and the subsequent accumulation of membrane phospholipid-derived metabolites in HCAEC exposed to hypoxia or thrombin stimulation alone, and particularly in combination, have important implications in inflammation and arrhythmogenesis in atherosclerosis/thrombosis and subsequent myocardial ischemia.
Critical role of 5′-AMP-activated protein kinase in the stimulation of glucose transport in response to inhibition of oxidative phosphorylation
Authors: Jing Ming , Ismail-Beigi Faramarz
Published: August 2006

5′-AMP-activated protein kinase (AMPK) functions as an energy sensor to provide metabolic adaptation under conditions of ATP depletion, such as hypoxia and inhibition of oxidative phosphorylation. Whether activation of AMPK is critical for stimulation of glucose transport in response to inhibition of oxidative phosphorylation is unknown. Here we found that treatment of Glut1-expressing Clone 9 cells with sodium azide (5 mM for 2 h) or the AMPK activator 5′-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR, 2 mM for 2 h) stimulated the rate of glucose transport by two- to fourfold. Use of small interference RNA (siRNA) directed against AMPKα1 or AMPKα1 + AMPKα2 (total AMPKα) resulted in a significant inhibition of the glucose transport response and the content of phosphorylated AMPKα1 + phosphorylated AMPKα2 (total p-AMPKα) and phosphorylated acetyl-CoA carboxylase (p-ACC) in response to azide. Transfection with siRNA directed against AMPKα2 did not affect the glucose transport response. The efficacy of transfection with siRNAs in reducing AMPK content was confirmed by Western blotting. Incubation of cells with compound C, an inhibitor of AMPK, abrogated the glucose transport response and abolished the increase in total p-AMPK in azide-treated or hypoxia-exposed cells. Simultaneous exposure to azide and AICAR did not augment the rate of transport in response to AICAR alone. There was no evidence of coimmunoprecipitation of total p-AMPKα with Glut1. However, LKB1 was associated with total p-AMPKα. We conclude that activation of AMPK plays both a sufficient and a necessary role in the stimulation of glucose transport in response to inhibition of oxidative phosphorylation.
Biomechanical regulation of hedgehog signaling in vascular smooth muscle cells in vitro and in vivo
Authors: Morrow David , Sweeney Catherine , Birney Yvonne A. , Guha Shaunta , Collins Nora , Cummins Philip M. , Murphy Ronan , Walls Dermot , Redmond Eileen M. , Cahill Paul A.
Published: August 2006

Hedgehog (Hh) signaling has recently been shown to be both responsive to mechanical loading in vitro and to control vascular development in vivo. We investigated the role of cyclic strain and pulsatile flow in modulating Hh signaling and growth of adult rat vascular smooth muscle cells (SMC) in culture. Exposure of SMC to defined equibiaxial cyclic strain (0% and 10% stretch, 60 cycles/min, for 24 h) significantly decreased sonic hedgehog (Shh) and patched 1 (Ptc1) expression while concurrently inhibiting Gli2-dependent promoter activity and mRNA expression, respectively. Cyclic strain significantly decreased SMC proliferation (cell counts and proliferating cell nuclear antigen expression) concomitant with a marked increase in SMC apoptosis (fluorescence-activated cell sorter analysis, acridine orange staining of apoptotic nuclei and Bax/Bcl-xL ratio). These strain-induced changes in proliferation and apoptosis were significantly attenuated following addition of either recombinant Shh (3.5 μg/ml) or overexpression of the Notch 3 intracellular domain (Notch IC). Further studies using a perfused transcapillary culture system demonstrated a significant decrease in Hh signaling in SMC following exposure of cells to increased pulsatile flow concomitant with a decrease in proliferation and an increase in apoptosis. Finally, the pulsatile flow-induced decreases in Hh signaling were validated in vivo following flow-induced rat carotid arterial remodeling after 28 days. These data suggest that Hh expression is diminished by biomechanical stimulation in vitro and in vivo and thus may play a fundamental role in arterial remodeling and atherogenesis in vivo.
TRPM7 is a stretch- and swelling-activated cation channel involved in volume regulation in human epithelial cells
Authors: Numata Tomohiro , Shimizu Takahiro , Okada Yasunobu
Published: August 2006

Stretch- and swelling-activated cation (SSAC) channels play essential roles not only in sensing and transducing external mechanical stresses but also in regulating cell volume in living cells. However, the molecular nature of the SSAC channel has not been clarified. In human epithelial HeLa cells, single-channel recordings in cell-attached and inside-out patches revealed expression of a Mg2+- and Gd3+-sensitive nonselective cation channel that is exquisitely sensitive to membrane stretch. Whole cell recordings revealed that the macroscopic cationic currents exhibit transient receptor potential (TRP) melastatin (TRPM)7-like properties such as outward rectification and sensitivity to Mg2+ and Gd3+. The whole cell cation current was augmented by osmotic cell swelling. RT-PCR and Western blotting demonstrated molecular expression of TRPM7 in HeLa cells. Treatment with small interfering RNA (siRNA) targeted against TRPM7 led to abolition of single stretch-activated cation channel currents and of swelling-activated, whole cell cation currents in HeLa cells. The silencing of TRPM7 by siRNA reduced the rate of cell volume recovery after osmotic swelling. A similar inhibition of regulatory volume decrease was also observed when extracellular Ca2+ was removed or Gd3+ was applied. It is thus concluded that TRPM7 represents the SSAC channel endogenously expressed in HeLa cells and that, by serving as a swelling-induced Ca2+ influx pathway, it plays an important role in cell volume regulation.
Stroma-derived factor (SDF-1/CXCL12) and human tumor pathogenesis
Authors: Kryczek Ilona , Wei Shuang , Keller Evan , Liu Rebecca , Zou Weiping
Published: August 2006

The chemokine stroma-derived factor (SDF-1/CXCL12) plays multiple roles in tumor pathogenesis. It has been demonstrated that CXCL12 promotes tumor growth and malignancy, enhances tumor angiogenesis, participates in tumor metastasis, and contributes to immunosuppressive networks within the tumor microenvironment. Therefore, it stands to reason that the CXCL12/CXCR4 pathway is an important target for the development of novel anti-cancer therapies. In this review, we consider the pathological nature and characteristics of the CXCL12/CXCR4 pathway in the tumor microenvironment. Strategies for therapeutically targeting the CXCL12/CXCR4 axis also are discussed.
Urethane inhibits the GABAergic neurotransmission in the nucleus of the solitary tract of rat brain stem slices
Authors: Accorsi-Mendonça Daniela , Leão Ricardo M. , Aguiar José F. , Varanda Wamberto A. , Machado Benedito H.
Published: August 2006

Because urethane is a widely used anesthetic in animal experimentation, in the present study, we evaluated its effects on neurons of the nucleus of the solitary tract (NTS) in brain stem slices from young rats (25–30 days old). Using the whole cell configuration of the patch-clamp technique, spontaneous postsynaptic currents (sPSCs) and evoked excitatory postsynaptic currents (eEPSCs) were recorded. Urethane (20 mM) decreased by ∼60% the frequency of GABAergic sPSCs (1.0 ± 0.2 vs. 0.4 ± 0.1 Hz) but did not change the frequency, amplitude, or half-width of glutamatergic events or TTX-resistant inhibitory sPSCs [miniature inhibitory postsynaptic currents (IPSCs)]. Miniature IPSCs were measured in the presence of urethane plus 1 mM diazepam (1 mM), and no changes were seen in their amplitude. This suggests that the GABA concentration in the NTS synapses is set at saturating level. We also evaluated the effect of urethane on eEPSCs, and no significant change was observed in the amplitude of N-methyl-d-aspartate [NMDA; 44.2 ± 11.5 vs. 37.6 ± 10.6 pA (holding potential = 40 mV)] and non-NMDA currents [204.4 ± 35.5 vs. 196.6 ± 31.2 pA (holding potential = −70 mV)]. Current-clamp experiments showed that urethane did not alter the action potential characteristics and passive membrane properties. These data suggest that urethane has an inhibitory effect on GABAergic neurons in the NTS but does not change the spontaneous or evoked excitatory responses.
Effects of Stimulus Azimuth and Intensity on the Single-Neuron Activity in the Auditory Cortex of the Alert Macaque Monkey
Authors: Woods Timothy M. , Lopez Steve E. , Long James H. , Rahman Joanne E. , Recanzone Gregg H.
Published: August 2006

It has been hypothesized that the primate auditory cortex is composed of at least two processing streams, one of which is believed to selectively process spatial information. To test whether spatial information is differentially encoded in different auditory cortical fields, we recorded the responses of single neurons in the auditory cortex of alert macaque monkeys to broadband noise stimuli presented from 360° in azimuth at four different absolute intensities. Cortical areas tested were core areas A1 and rostral (R), caudal belt fields caudomedial and caudolateral, and more rostral belt fields middle lateral and middle medial (MM). We found that almost all neurons encountered showed some spatial tuning. However, spatial selectivity measures showed that the caudal belt fields had the sharpest spatial tuning, A1 had intermediate spatial tuning, and areas R and MM had the least spatial tuning. Although most neurons showed their best responses to contralateral space, best azimuths were observed across the entire 360° of tested space. We also noted that although the responses of many neurons were significantly influenced by eye position, eye position did not systematically influence any of the spatially dependent responses that we measured. These data are consistent with the hypothesis that caudal auditory cortical fields in the primate process spatial features more accurately than the core and more rostral belt fields.
Hybrid Systems Analysis of the Control of Burst Duration by Low-Voltage-Activated Calcium Current in Leech Heart Interneurons
Authors: Olypher Andrey , Cymbalyuk Gennady , Calabrese Ronald L.
Published: August 2006

The leech heartbeat CPG is paced by the alternating bursting of pairs of mutually inhibitory heart interneurons that form elemental half-center oscillators. We explore the control of burst duration in heart interneurons using a hybrid system, where a living, pharmacologically isolated, heart interneuron is connected with artificial synapses to a model heart interneuron running in real-time, by focusing on a low-voltage-activated (LVA) calcium current ICaS. The transition from silence to bursting in this half-center oscillator occurs when the spike frequency of the bursting interneuron declines to a critical level, fFinal, at which the inhibited interneuron escapes owing to a build-up of the hyperpolarization-activated cation current, Ih. We varied ICaSinactivation time constant either in the living heart interneuron or in the model heart interneuron. In both cases, varying ICaSinactivation time constant did not affect fFinalof either interneuron, but in the varied interneuron, the time constant of decline of spike frequency during bursts to fFinaland thus the burst duration varied directly and nearly linearly with ICaSinactivation time constant. Bursts of the opposite, nonvaried interneuron did not change. We show also that control of burst duration by ICaSinactivation does not require synaptic interaction by reconstituting autonomous bursting in synaptically isolated living interneurons with injected ICaS. Therefore inactivation of LVA calcium current is critically important for setting burst duration and thus period in a heart interneuron half-center oscillator and is potentially a general intrinsic mechanism for regulating burst duration in neurons.
Afferent Innervation Patterns of the Pigeon Horizontal Crista Ampullaris
Authors: Haque Asim , Huss David , Dickman J. David
Published: August 2006

The vestibular semicircular canals are responsible for detection of rotational head motion although the precise mechanisms underlying the transduction and encoding of movement information are still under study. In the present investigation, we utilized neural tracers and immunohistochemistry to quantitatively examine the topology and afferent innervation patterns of the horizontal semicircular canal crista (HCC) in pigeons ( Columba livia). Two hundred and eighty-six afferents from five horizontal canal organs were identified of which 92 units were sufficiently labeled and isolated to perform anatomical reconstructions. In addition, a three-dimensional contour map of the crista was constructed. Bouton afferents were located only in the peripheral regions of the receptor epithelium. Bouton afferents had the most complex innervation patterns with significantly longer and more numerous branches as well as a higher branch order than any other fiber type. Bouton fibers also contained significantly more bouton terminals than did dimorph afferents. Calyx afferents were located only in the apex and central planar regions. Calyx fibers had the largest axonal diameters yet the smallest fiber lengths and innervation areas, the fewest number of branches, the lowest branch order, and the fewest total number of terminals of all fiber types. Dimorph afferents were located throughout the central crista with afferent terminations that were larger and more complex than calyx fibers but less so than bouton fibers. Overall, the pigeon HCC morphology and innervation shares many common features with those of other animal classes.
Representation of the Spatial Relationship Among Object Parts by Neurons in Macaque Inferotemporal Cortex
Authors: Yamane Yukako , Tsunoda Kazushige , Matsumoto Madoka , Phillips Adam N. , Tanifuji Manabu
Published: August 2006

We investigated object representation in area TE, the anterior part of monkey inferotemporal (IT) cortex, with a combination of optical and extracellular recordings in anesthetized monkeys. We found neurons that respond to visual stimuli composed of naturally distinguishable parts. These neurons were sensitive to a particular spatial arrangement of parts but less sensitive to differences in local features within individual parts. Thus these neurons were activated when arbitrary local features were arranged in a particular spatial configuration, suggesting that they may be responsible for representing the spatial configuration of object images. Previously it has been reported that many neurons in area TE respond to visual features less complex than natural objects, but it has remained unclear whether these features are related to local features of object images or to more global features. These results indicate that TE neurons represent not only local features but also global features such as the spatial relationship among object parts.
Evaluation in the Wild: A Distributed Cognition Perspective on Teacher Assessment
Authors: Halverson Richard R. , Clifford Matthew A.
Published: August 2006

Purpose: The authors adapted distributed cognition theory to provide a detailed account of how schoolleaders use knowledge of the new programs, existing initiatives, andschool contexts to guide policy implementation.

Research Design: The study used distributed cognition theory to show how policy implementation studies provide an occasion to understand the influence of context on practice. The article focuses on a case study of (a) a suburban district design of a teacher evaluation policy and (b) a principal’s effort to use the evaluation program with the teachers in her middleschool.The authors adaptedthe distributedcognitiontheory to provide ananalytic framework to better address the issues of school leadership.

Findings: The authors found that the design of the policy required teacher evaluators to address the tensions between summative and formative evaluation implicit in the program design. In this case, the principal relied heavily on her discretion to determine which features of the teacher evaluationpolicywouldbe emphasizedwith different teachers. The case also providedinsightinto how the principalreconciledthe demandsof evaluation with ongoing instructional and personnel demands.

Conclusions: The distributed cognition framework provided a valuable tool for organizing close studies of the cognitive and contextual dimensions of leadership practice and can provide valuable information about how policies can be designed and used to shape real changes in everyday practice.
Toward a New Conceptualization of Vision in the Work of Educational Leaders: Cases of the Visionary Archetype
Authors: Ylimaki Rose M.
Published: August 2006

Purpose: Across mainstream educational leadership literature, the term vision has had two primary definitions: (a) a leader’s image of the future and (b) change goals. Translating vision into practice has become increasingly difficult, however, as educators have been bombarded with conflicting images and goals for schools. This article is conceptual in nature, using the findings from a previous empirical study of collaboration and instructional leadership to propose a new way of thinking about vision in terms of the work of educational leaders.

Proposed Conceptual Argument: The leaders’ notions of vision suggest principles of the visionary archetype that have not been considered in the extant literature, including four ways of seeing (intuition, perception, insight, and holistic seeing). Thus, literature on the visionary archetype is used as a lens to conceptualize these leaders’ notions of vision. Metaphors are used to present three cases of the visionary archetype and change contexts in which the visionary appears to exist. A discrepant case metaphor is also presented in which a curriculum director defined and used vision more traditionally. Based on these understandings, the author suggests a new conceptualization of vision—namely, that vision is a dynamic interaction among inner human resources (e.g., insight, intuition, and perception), an outward perspective (on larger educational ideals, research, and policies), and the context of a particular visioning situation.

Implications: The article concludes with implications for future research on the role of vision in other educator roles and settings as well as recommendations for vision makers of all kinds.
Relationships Among Teams, Culture, Safety, and Cost Outcomes
Authors: Brewer Barbara B.
Published: August 2006

The objective of this study is to test the transtheoretical integration model, which proposes relationships among team-based phenomena and patient safety and resource-use outcome variables. The sample consisted of 411 nursing staff ( n = 372) and multidisciplinary team members ( n = 39) from 16 medical surgical units. Staff were surveyed to evaluate their perceptions of hospital culture, work group design, and positive and negative team processes. Managers provided data concerning outcome variables of patient falls with injury, average length of stay (LOS), and labor and supply expenses for their patient care units. A group-type hospital culture predicted fewer patient falls with injury; a developmental-type hospital culture predicted higher patient care unit costs. Team design and processes were predictive of longer LOS for patients on medical-surgical units. Conclusions of the study were that hospital contexts external to the patient care unit may be important contributors to patient safety and resource use on nursing units.
Hospital Demand for Licensed Practical Nurses
Authors: Spetz Joanne , Dyer Wendy T. , Chapman Susan , Seago Jean Ann
Published: August 2006

Despite evidence that hospital use of licensed practical nurses (LPNs) declined in the 1990s, the current registered nurse (RN) shortage has prompted interest in LPNs as substitutes for RNs. Hospitals, being the dominant employer of RNs, have an economic incentive to use less expensive LPNs as substitutes. Beside wages, there are several forces underlying hospital demand for LPNs. In this article, the authors model and estimate hospital demand for LPNs as a function of nurse wages and hospital, market, and patient characteristics using a longitudinal data set of short-term general hospitals in the United States. The authors find evidence that higher RN wages increase hospital demand for LPNs, both in levels and relative to RNs, suggesting that hospitals at least partially substitute RNs with LPNs.
Teaching and Community Hospital Work Environments
Authors: Hall Linda McGillis , Doran Diane , Sidani Souraya , Pink Leah
Published: August 2006

The Institute of Medicine report suggests that nursing work environments experience threats to patient safety related to organizational management and workforce deployment practices, work design, and organizational culture. Organizational factors contribute to nursing and potentially patient outcomes, yet few studies have examined the differences in practices perceived by nurses employed in different settings. Nurses from 16 medical and surgical units in eight randomly selected acute care hospitals representing teaching and community organizations participated in this project. Nurses working in teaching hospitals reported lower levels of role tension, yet their perceptions of the quality of work, the work environment, nursing unit leadership, quality of care, and levels of job stress and job satisfaction were higher than their colleagues in the community sites. This study highlights some important differences between teaching and community hospitals that can inform nurse executives and policy makers of the unique work–life issues for different groups of nurses.
Unit Type Differences in RN Workgroup Job Satisfaction
Authors: Boyle Diane K. , Miller Peggy A. , Gajewski Byron J. , Hart Sara E. , Dunton Nancy
Published: August 2006

Using cross-sectional data from the 2004 National Database of Nursing Quality Indicators (NDNQI) RN Satisfaction Survey, differences in RN workgroup job satisfaction were examined among 10 unit types—medical-surgical, step-down, critical care, pediatric, maternal-newborn, psychiatric, emergency department, rehabilitation, surgical services, and outpatient clinics and labs. The national sample included RN workgroups in 2,900 patient care units (55,516 RNs; 206 hospitals in 44 states). Workgroup satisfaction across all unit types was moderate. RN workgroups in pediatric units were the most satisfied, whereas those in surgical services and emergency department unit types were least satisfied. A consistent finding across all unit types was high satisfaction with the specific domains of nurse-to-nurse interaction, professional status, and professional development versus much lower satisfaction with task, decision making, and pay. Findings can be used to inform and develop investigations that examine specific aspects of the work environment for RN workgroups in various unit types.
Successful treatment with duloxetine in a case of treatment refractory bulimia nervosa: a case report
Authors: Hazen Eric , Fava Maurizio
Published: August 2006

The authors report a case of treatment refractory bulimia nervosa successfully treated with duloxetine, a combined serotonin and norepinephrine reuptake inhibitor, with complete remission of the patient's bingeing and purging behaviours. This case is discussed in the context of existing literature on the psychopharmacology of bulimia nervosa.
Plasma oxytocin levels in depression and their correlation with the temperament dimension of reward dependence
Authors: Bell Caroline J. , Nicholson Helen , Mulder Roger T. , Luty Sue E. , Joyce Peter R.
Published: August 2006

Evidence suggests that the neuropeptide oxytocin plays a role in social affiliation. This behaviour may be related more to personality dimensions than specific psychiatric diagnoses. This study investigated the relationship between plasma oxytocin levels and personality dimensions using the Temperament and Character Inventory (TCI) in 60 outpatients with major depression. The strongest correlation was between plasma oxytocin levels and the temperament dimension of Reward Dependence (0.425 Pearson correlation). This suggested that 17% of the variance in plasma oxytocin levels was explained by the Reward Dependence scores. There was a significant positive correlation between plasma oxytocin levels and the Reward Dependence personality dimension
Assessing cortisol and dehydroepiandrosterone (DHEA) in saliva: effects of collection method
Authors: Gallagher Peter , Leitch Melville M. , Massey Anna E. , McAllister-Williams R. Hamish , Young Allan H.
Published: August 2006

An increasing number of studies are utilizing saliva sampling as a method of assessing adrenal steroid secretion. Saliva samples have certain advantages over plasma, being non-invasive and easily collected. However, some methods of collection may compromise the accuracy of the assay, particularly those which employ aids to stimulate saliva production. We sought to compare the accuracy of cortisol and dehydroepiandrosterone (DHEA) measurement by examining the association between plasma levels, saliva and saliva collected using a citric acid-treated salivette device. Twenty six healthy male volunteers were recruited for the study. To increase the range of steroid levels in the samples collected, half the subjects were pre-treated with hydrocortisone (20mg, twice a day for 7 days) and half with placebo. Saliva samples were then collected from each subject using both a ‘passive drool’ method and a citric acid-treated salivette. A plasma sample was also collected. Cortisol and DHEA levels were measured by radioimmunoassay. For cortisol levels, both methods of saliva collection correlated highly with plasma levels and with each other (r 0.85; R2 0.72 for all). For DHEA levels, only saliva samples collected using the unstimulated collection method correlated with plasma levels. DHEA collected using the salivette device did not correlate significantly with either plasma or the unstimulated saliva (r 0.2;R2 0.04). It is crucial that future studies are aware of these issues and are cognizant of the effects of the method of collection when examining steroid levels in saliva.