bluuebunny/crossref_metadata_2025 huggingface dataset:
Ellipsometric study of polymer thin films: Nonlinear optical guest-host system
Authors: Lee Kang Ju , Kang Tae Dong , Lee Ho Suk , Lee Hosun , Cho Min Joo , Lee Seung Hwan , Choi Dong Hoon
Published: April 2005

We measured the pseudo-dielectric functions of several nonlinear optical (NLO) polymeric systems using spectroscopic ellipsometry in the spectral range between 0.8 and 4.7eV. We fabricated the thin films after doping the nonlinear optical active chromophores into amorphous polycarbonate to show good optical transparency. We measured the ultraviolet-visible absorption spectra of the NLO chromophores in the film state. In order to determine the dielectric functions, we employed the Bruggeman effective medium approximation, assuming a mixture of two phases: host and guest. We used the Cauchy model for the dielectric function of the host polymer and a parametric optical constant model for that of the guest chromophore. We discussed the variation of the dielectric functions and the transition energies for various host-guest systems. In the gradient donor structural chromophores, we observed a decrease of the highest occupied molecular orbital (HOMO) lowest-unoccupied-molecular-orbital (LUMO) transition energy, and found a transition at about 3eV. The decrease of HOMO—LUMO transition energy is attributed to the increase of electron donability and conjugative effect. We could fit the volume fractions of host and guest using spectroscopic ellipsometry, and compared them with the values estimated from the chemical structures of the molecules.
Optimization of conductivity in p-type GaN∕InGaN-graded superlattices
Authors: Kauser M. Z. , Osinsky A. , Dabiran A. M. , Pearton S. J.
Published: April 2005

Carrier transport simulations show that significantly improved vertical and lateral electrical conductivity (σV and σL) can be achieved in p-type GaN∕InGaN superlattices utilizing composition-graded p-InGaN layers. Compared to typical modulation-doped superlattices, the barrier height and the sheet-hole density in the p-InGaN wells were, respectively, more than eight times lower and 2.6 times higher. This achievement is due to the combination of a number of factors, including polarization charge distribution in the graded layers, an adjusted Mg-doping profile, and a shallower acceptor activation energy in InGaN. The optimized superlattice design leads to an improvement of more than eleven orders of magnitude in σV compared to typical superlattices while maintaining a value for σL that is better than that of bulk p-InGaN. Both σV and σL are found to improve at higher temperatures in the optimized structure.
Instability of miscible interfaces in a cylindrical tube
Authors: Balasubramaniam R. , Rashidnia N. , Maxworthy T. , Kuang J.
Published: April 2005

We report experimental results on the displacement of a less viscous liquid by a more viscous, miscible liquid in a vertical tube of small diameter. The liquids used are silicone oils of various viscosities. The more viscous fluid has a higher density than the less viscous fluid. Both upward displacement and downward displacement have been studied. Our observations show that for downward displacement, the “interface” between the liquids can be unstable and exhibits an asymmetric, sinuous shape. During upward displacement, the interface forms an axisymmetric finger of the intruding liquid. At the tip of the main finger, a spike of the more viscous liquid is observed under some conditions. The Reynolds number is negligibly small in these experiments and the Peclet number for mass transfer is O(50)–O(105). The influence of gravity is characterized by the dimensionless parameter F=gΔρd2∕μU where g is the acceleration due to gravity, Δρ is the density difference between the fluids, d is the tube diameter, μ is the viscosity of the more viscous fluid, and U is the displacement speed. A plot of F versus the viscosity ratio of the fluids is constructed to delineate the stable and unstable regimes of flow.
A convective turbulent state that spatially orders upon increased drive
Authors: Park Cheol Soo , Clark Noel A. , Noble Richard D.
Published: April 2005

A nematic liquid crystal in a slot electrohydrodynamic convection geometry exhibits, with increasing drive, enhanced noisy high-dimensional flow fluctuations and weakened low-dimensional ordered flow, reaching a turbulent state with only short range velocity correlations in space and time for sufficiently high voltage. Upon additional voltage increase this disorganized turbulent state develops spatial order with extended temporal correlations, in the form of a one-dimensional periodic array of turbulent jet-like plumes along the slot. This array becomes more robust with reduced disorder and faster fluctuations as the drive is further increased. Remarkably this ordering depends sensitively on liquid crystal alignment conditions on the surface of the slot cell.
Turbulence characteristics in sharp open-channel bends
Authors: Blanckaert K. , de Vriend H. J.
Published: April 2005

In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation (secondary flow) and a turbulence activity in the outer bend that is significantly less than in the equivalent straight uniform shear flow. Measured distributions are given of the turbulent kinetic energy, its production, the mixing coefficients, some parameters characterizing the turbulence structure, and the fourth-order correlations of the turbulent velocity fluctuations. The transport equation for the turbulent kinetic energy is evaluated term by term, on the basis of the measured data. The results show that the turbulence structure is different from straight uniform flow, in that the Reynolds stress tensor is more diagonally dominant. This is shown to be the main cause of the observed reduction of turbulence activity in the outer bend. The usual two-equation turbulence closure models include a transport equation for the turbulent kinetic energy, but they do not account for this modified turbulence structure. The departures of the measured turbulence structure from its equivalent in straight uniform shear flow are related to a curvature-flux-Richardson number Rf which includes the streamline curvature. Such a relation may be useful to improve simple turbulence closure models for curved open-channel flow.
Strict deformation quantization for a particle in a magnetic field
Authors: Măntoiu Marius , Purice Radu
Published: April 2005

Recently, we introduced a mathematical framework for the quantization of a particle in a variable magnetic field. It consists in a modified form of the Weyl pseudodifferential calculus and a C*-algebraic setting, these two points of view being isomorphic in a suitable sense. In the present paper we leave Planck’s constant vary, showing that one gets a strict deformation quantization in the sense of Rieffel. In the limit ℏ→0 one recovers a Poisson algebra induced by a symplectic form defined in terms of the magnetic field.
The flow of thin liquid films over spinning disks:  Hydrodynamics and mass transfer
Authors: Matar Omar K. , Lawrence Chris J. , Sisoev Grigori M.
Published: April 2005

We study the hydrodynamics and mass transfer associated with gas absorption into a thin liquid film flowing over a spinning disk. We use the thin-layer approximation in conjunction with the Karman–Polhausen method to derive evolution equations for the film thickness and the volumetric flow rates in the radial and azimuthal directions. We also use the integral balance method to derive evolution equations for the thickness of the diffusion boundary layer as well as the concentration of solute at the disk surface. Numerical solutions of these partial differential equations, which govern the hydrodynamics and the associated mass transfer, reveal the formation of large finite-amplitude waves and elucidate their significant effect on the mass-transfer characteristics. We illustrate this dependence quantitatively by examining the effect of system parameters on the time-averaged and spatially averaged Sherwood numbers. The results are assessed by comparison with computations of the parabolized convective diffusion equation and experimental data.
Fabrication and characterization of solution-processed methanofullerene-based organic field-effect transistors
Authors: Singh Th. B. , Marjanović N. , Stadler P. , Auinger M. , Matt G. J. , Günes S. , Sariciftci N. S. , Schwödiauer R. , Bauer S.
Published: April 2005

The fabrication and characterization of high-mobility, n-channel organic field-effect transistors (OFET) based on methanofullerene [6,6]-phenyl C61-butyric acid methyl ester using various organic insulators as gate dielectrics is presented. Gate dielectrics not only influence the morphology of the active semiconductor, but also the distribution of the localized states at the semiconductor-dielectric interface. Spin-coated organic dielectrics with very smooth surfaces provide a well-defined interface for the formation of high quality organic semiconductor films. The charge transport and mobility in these OFET devices strongly depend on the choice of the gate dielectric. The electron mobilities obtained are in the range of 0.05–0.2cm2V−1s−1. Most of the OFETs fabricated using organic dielectrics exhibit an inherent hysteresis due to charge trapping at the semiconductor-dielectric interface. Devices with a polymeric electret as gate dielectric show a very large and metastable hysteresis in its transfer characteristics. The observed hysteresis is found to be temperature dependent and has been used to develop a bistable memory element.
On the band structure lineup of ZnO heterostructures
Authors: Mönch Winfried
Published: April 2005

The interface-induced gap states (IFIGS) are the fundamental mechanism which determines the band structure lineup at semiconductor interfaces. The valence-band offsets of semiconductor heterostructures are given by the difference of the respective IFIGS branch-point energies and electric-dipole terms which may be omitted for elemental group-IV semiconductors, SiC, as well as the III–V, II–VI, and I–III–VI2 compounds and alloys. The branch-point energy of ZnO is determined as 3.04±0.21eV from an analysis of experimental valence-band offsets reported for various ZnO heterostructures.
Numerical simulations of layered and blended organic photovoltaic cells
Authors: Haerter J. O. , Chasteen S. V. , Carter S. A. , Scott J. C.
Published: April 2005

We present results obtained from numerical simulations of organic photovaltaic cells as the donor–acceptor morphology evolves from sharply defined layers, to partial blends and finally homogeneous blends. As the mixing percentage increases, the exciton dissociation increases and the diffusion counter-current decreases, resulting in substantially greater short circuit currents but reduced open circuit voltages. Blended structures are more sensitive to mobility than layers due to recombination throughout the bulk. Our model indicates that solar power efficiencies greater than 10% can be achieved when the zero-field charge mobilities approach 10−3cm2∕Vs for partially blended structures.
Giant random telegraph signals in the carbon nanotubes as a single defect probe
Authors: Liu Fei , Bao Mingqiang , Kim Hyung-jun , Wang Kang L. , Li Chao , Liu Xiaolei , Zhou Chongwu
Published: April 2005

Giant random telegraph signals (RTSs) are observed in p-type semiconducting single-wall carbon nanotube (SWNT) field-effect transistors (FETs). The RTSs are attributed to the trapping and detrapping of the two defects inside SiO2 or in the interface between SWNT and SiO2. The amplitude of the RTSs is up to 60% of total current. The giant switching amplitude of RTSs is believed to be caused by the strong mobility modulation originated from the charging of the defects in the one-dimensional carbon nanotube channels with an ultrasmall channel width on the order of 1–3 nm. The potential application of RTSs in SWNT as a sensitive probe to study single defects is discussed.
Time and Technology
Authors: Petersson Dag
Published: April 2005

In this paper I focus on the concept of diagrams, as they have been appropriated from a Deleuzean discourse into the philosophy of Manuel DeLanda. For strategical reasons Gilles Deleuze reiterated on several occasions a caution against subjecting diagrams to history. Yet, this is exactly what DeLanda seems to invite us to do. To counter this tendency, without abandoning DeLanda's perspective, a new passage between the virtual plane of consistency and concrete machines is invented. This paper is not a final solution, but an elaborated strategy which points ahead towards intensified efforts in investigating the evolution of visual screens.
Materiality, Subjectification, and Government: The Geographies of Britain's Motorway Code
Authors: Merriman Peter
Published: April 2005

In this paper I provide a critical discussion of Foucault's work on government and governmentality. I argue that geographers have tended to overlook the ways in which practices of self-government and subjectification are performed in relation to programmes of government, and suggest that they should examine the technical devices which are embedded in networks of government. Drawing upon these observations I suggest how geographers might proceed, tracing the geographies of a specific artefact: the British government's 1958 Motorway Code. I examine how the code was designed to serve as a technology of government that could shape the conduct of fairly mobile and distant subjects, enabling them to govern their conduct and the movements of their vehicles.
Space, Politics, and the Political
Authors: Dikeç Mustafa
Published: April 2005

In this paper I offer a reading of Jacques Rancière's conceptualization of politics, and consider its implications for the links between space, politics, and the political. I provide an overview of Rancière's conceptualizations of ‘the police’, politics, and the political, and try to recover the spatiality of these notions. Based on this overview, the argument pursued in the paper is that space does not become political just by virtue of being full of power or competing interests. It becomes political by becoming the place where a wrong can be addressed and equality can be demonstrated. This definition makes space not only an integral element of the defining moment of the political, but an integral element of the disruption of the normalized order of domination as well.
Local Water Diversely Known: Walkerton Ontario, 2000 and after
Authors: Parr Joy
Published: April 2005

In this narrative of the water contamination in Walkerton, Ontario, in 2000–02 I consider the local priorities defining good water. These vernacular understandings emphasised taste, softness, and thrift in municipal water, and they highly valued local sovereignty in matters of water quality, and solidarity as a quality of local citizenship. By using contemporaneous evidence from media reports and the judicial enquiry into the incident, I trace how the qualities of good water were redefined, and with them community standards of safety, expertise, and risk. The emphasis on community consent to vernacular water monitoring practices and the implications of this shared responsibility differ from the journalistic and judicial accounts which emphasise individual culpability.
Stress-induced enhancement of leukocyte trafficking into sites of surgery or immune activation
Authors: Viswanathan Kavitha , Dhabhar Firdaus S.
Published: April 2005

Effective immunoprotection requires rapid recruitment of leukocytes into sites of surgery, wounding, infection, or vaccination. In contrast to immunosuppressive chronic stressors, short-term acute stressors have immunoenhancing effects. Here, we quantify leukocyte infiltration within a surgical sponge to elucidate the kinetics, magnitude, subpopulation, and chemoattractant specificity of an acute stress-induced increase in leukocyte trafficking to a site of immune activation. Mice acutely stressed before sponge implantation showed 200–300% higher neutrophil, macrophage, natural killer cell, and T cell infiltration than did nonstressed animals. We also quantified the effects of acute stress on lymphotactin- (LTN; a predominantly lymphocyte-specific chemokine), and TNF-α- (a proinflammatory cytokine) stimulated leukocyte infiltration. An additional stress-induced increase in infiltration was observed for neutrophils, in response to TNF-α, macrophages, in response to TNF-α and LTN, and natural killer cells and T cells in response to LTN. These results show that acute stress initially increases trafficking of all major leukocyte subpopulations to a site of immune activation. Tissue damage-, antigen-, or pathogen-driven chemoattractants subsequently determine which subpopulations are recruited more vigorously. Such stress-induced increases in leukocyte trafficking may enhance immunoprotection during surgery, vaccination, or infection, but may also exacerbate immunopathology during inflammatory (cardiovascular disease or gingivitis) or autoimmune (psoriasis, arthritis, or multiple sclerosis) diseases.
Reverse recruitment: The Nup84 nuclear pore subcomplex mediates Rap1/Gcr1/Gcr2 transcriptional activation
Authors: Menon Balaraj B. , Sarma Nayan J. , Pasula Satish , Deminoff Stephen J. , Willis Kristine A. , Barbara Kellie E. , Andrews Brenda , Santangelo George M.
Published: April 2005

The recruitment model for gene activation presumes that DNA is a platform on which the requisite components of the transcriptional machinery are assembled. In contrast to this idea, we show here that Rap1/Gcr1/Gcr2 transcriptional activation in yeast cells occurs through a large anchored protein platform, the Nup84 nuclear pore subcomplex. Surprisingly, Nup84 and associated subcomplex components activate transcription themselves
in vivo
when fused to a heterologous DNA-binding domain. The Rap1 coactivators Gcr1 and Gcr2 form an important bridge between the yeast nuclear pore complex and the transcriptional machinery. Nucleoporin activation may be a widespread eukaryotic phenomenon, because it was first detected as a consequence of oncogenic rearrangements in acute myeloid leukemia and related syndromes in humans. These chromosomal translocations fuse a homeobox DNA-binding domain to the human homolog (hNup98) of a transcriptionally active component of the yeast Nup84 subcomplex. We conclude that Rap1 target genes are activated by moving to contact compartmentalized nuclear assemblages, rather than through recruitment of the requisite factors to chromatin by means of diffusion. We term this previously undescribed mechanism “reverse recruitment” and discuss the possibility that it is a central feature of eukaryotic gene regulation. Reverse recruitment stipulates that activators work by bringing the DNA to an nuclear pore complex-tethered platform of assembled transcriptional machine components.
On the centralizer of a regular, semi-simple, stable conjugacy class
Authors: Gross Benedict
Published: April 2005

We describe the isomorphism class of the torus centralizing a regular, semi-simple, stable conjugacy class in a simply-connected, semi-simple group.
Inducible Nitric Oxide Synthase Inhibition Potentiates Multiple Organ Dysfunction Induced by Endotoxin in Conscious Rats
Authors: Lee Chia-Chi , Lin Nien-Tseng , Hsu Yung Hsing , Chen Hsing I
Published: April 2005

This study was designed to investigate the effects of inducible nitric oxide synthase (iNOS) inhibition with S-methylisothiourea (SMT) and L-N6-(1-iminoethyl)-lysine (L-Nil) on the endotoxemia induced by intravenous lipopolysaccharide (LPS, 10 mg/kg) in conscious rats. Arterial pressure (AP), heart rate (HR), WBC, platelets, plasma nitrite/nitrate, tumor necrosis factor α (TNFα), and biochemical factors were measured for 24 hours after LPS with or without iNOS inhibitors. RT-PCR was employed to determine the iNOS and endothelial NOS (eNOS) mRNA. Pathologic examinations of the liver and heart were performed. SMT and L-Nil improved the systemic hypotension and increased the HR after LPS. These agents attenuated the LPS-induced leukocytopenia and thrombocytopenia and the increase in nitrite/nitrate. However, iNOS inhibition aggravated the LPS-induced changes in TNFα, all biochemical factors, and the hepatic and cardiac tissue damage. The iNOS mRNA, but not the eNOS, was reduced. Our results in conscious rats indicate that iNOS inhibition enhances the organ dysfunction and tissue damage in sepsis. The discrepancy may be attributed to the method for evaluating the sepsis and the effects of anesthesia. Further investigation is required to ensure the effects of iNOS inhibition on sepsis before iNOS inhibitors can be applied in clinical cases with sepsis.
Antithrombotic Properties of the Thromboxane A2/Prostaglandin H2 Receptor Antagonist S18886 on Prevention of Platelet-Dependent Cyclic Flow Reductions in Dogs
Authors: Maalej Nabil , Osman Hashim E , Shanmuganayagam Dhanansayan , Shebuski Ronald J , Folts John D
Published: April 2005

A potent thromboxane A2/PGH2 (TP)-receptor antagonist, S18886, was evaluated for its antithrombotic property in a dog model of acute periodic platelet-mediated thrombosis in stenosed coronary arteries with endothelial damage. After thrombosis had been obtained in 11 dogs, S18886 (300 μg/kg bolus) was administered IV. Heart rate, systemic blood pressure, and coronary blood flow were continuously recorded. Ex vivo whole blood platelet aggregation (PA), blood pH, hematocrit, platelet count, PO2, PCO2, and bleeding times were measured before and 30 minutes after administration of S18886. S18886 completely inhibited thrombosis in all dogs in approximately 5-10 minutes. No change in heart rate, blood pressure, pH, PO2, PCO2, platelet count, or bleeding time and a slight but significant elevation in hematocrit occurred. Infusion of epinephrine IV after complete inhibition of thrombosis by S18886 partially restored thrombosis in 3 of the 11 dogs. PA induced by collagen (4 μg/mL), collagen (0.25 μg/mL) plus epinephrine (1 μg/mL), collagen (1 μg/mL) plus epinephrine (1 μg/mL), ADP (40 μM) plus epinephrine (1 μg/mL), and phorbol 12-myristate 13-acetate (0.5 nM) were attenuated by 90 ± 8% (P < 0.005), 98 ± 2% (P < 0.05), 78 ± 6% (P < 0.005), 70 ± 10% (P < 0.005), and 28 ± 8% (P < 0.05), respectively. In conclusion, S18886 is a potent platelet inhibitor that attenuates in vivo platelet-dependent thrombosis in the experimental dog model and reduces ex vivo platelet aggregation.
Inhibition of cGMP-Dependent Protein Kinase Reverses Phenotypic Modulation of Vascular Smooth Muscle Cells
Authors: Dey Nupur B , Foley Kevin F , Lincoln Thomas M , Dostmann Wolfgang R
Published: April 2005

We have previously shown that type I cGMP-dependent protein kinase (PKG) can alter the phenotype of cultured vascular smooth muscle cells (VSMCs). Although the expression of contractile proteins in VSMCs has been shown to be modulated with the induction of PKG, experiments in which PKG inhibition brings about reduced expression of contractile markers have not been performed. To more thoroughly examine the role of PKG in the expression of contractile proteins, recombinant adenovirus containing the PKG coding sequence (AD-PKG) was used to induce gene expression and morphologic changes in adult rat aortic VSMCs. Cells expressing PKG, but not control adenovirus-infected cells, began to express a specific marker protein for the contractile phenotype, smooth muscle myosin heavy chain (SMMHC), within 48 hours of PKG induction. The morphology of the AD-PKG-infected cells began to change from a fibroblastic phenotype to a spindle-shaped phenotype within 72 hours after PKG induction. The specific cell-permeable PKG inhibitory peptide DT-2, but not control peptides, reversed the biochemical and morphologic changes associated with PKG expression. These results suggest that PKG expression and activity in cultured VSMCs is capable of altering the VSMC phenotype. These data also verify the intracellular action of DT-2 and reveal uptake and dynamic properties of this PKG-inhibiting peptide.
T-Cadherin Mediates Low-Density Lipoprotein-Initiated Cell Proliferation Via the Ca2+-Tyrosine Kinase-Erk1/2 Pathway
Authors: Kipmen-Korgun Dijle , Osibow Karin , Zoratti Cristina , Schraml Elisabeth , Greilberger Joachim , Kostner Gerhard M , Jürgens Günther , Graier Wolfgang F
Published: April 2005

The GPI-anchored protein T-cadherin was found to be an atypical LDL binding site that is expressed in various types of cells, including endothelial cells, smooth muscle cells, and neurons. Notably, the expression of T-cadherin was reduced in numerous types of cancers, although it was up-regulated in tumor-penetrating blood vessels, atherosclerotic lesions, and during neointima formation. Despite these intriguing findings, our knowledge of the physiological role and the signal transduction pathways associated with this protein is limited. Therefore, T-cadherin was overexpressed in the human umbilical vein-derived endothelial cell line EA.hy926, the human embryonic kidney cell line HEK293, and LDL-initiated signal transduction, and its consequences were elucidated. Our data revealed that T-cadherin serves as a receptor specifically for LDL. Following LDL binding to T-cadherin, mitogenic signal transduction was initiated that involved activation of PLC and IP3 formation, which subsequently yielded intracellular Ca2+ mobilization. Downstream to these early phenomena, activation of tyrosine kinase(s) Erk 1/2 kinase, and the translocation of NFκB toward the nucleus were found. Finally, overexpression of T-cadherin in HEK293 cells resulted in accelerated cell proliferation in an LDL-dependent manner, although cell viability was not influenced. Because LDL uptake was not facilitated by T-cadherin, our data suggest that T-cadherin serves as a signaling receptor for LDL that facilitates an LDL-dependent mitogenic signal in the vasculature.
HMG-CoA Reductase Inhibitors Reduce IκB Kinase Activity Induced by Oxidative Stress in Monocytes and Vascular Smooth Muscle Cells
Authors: Ortego Monica , Gómez-Hernández Almundena , Vidal Cristina , Sánchez-Galán Eva , Blanco-Colio Luis M , Martín-Ventura Jose L , Tuñón Jose , Diaz Cristina , Hernández Gonzalo , Egido Jesus
Published: April 2005

Reactive oxygen species, such as superoxide anion (O2
−) and hydrogen peroxide (H2O2), may act as second messengers of intracellular signaling and play a key role in the pathogenesis of atherosclerosis. The nuclear factor κB (NF-κB) is a redox-sensitive transcription factor that is involved in this process. The aim of the present study was to investigate the molecular mechanisms of action of statins on cultured vascular smooth muscle cells (VSMC) and monocytic cells (THP-1) under oxidative stress. In THP-1 and cultured VSMC, O2
− caused an increase in NF-κB activation (P < 0.05) that was correlated with inhibitory IκB-α degradation. Atorvastatin or simvastatin decreased NF-κB activation induced by oxidative stress by around 50% in both cell types and was correlated with the IκB-α levels. In monocytes, O2
− increased IκB kinase (IKK)-1 and IKK-2 activity (P < 0.05) and p38 and p42/44 activation and phosphorylation, which was reduced by statins. PD 98059 (p42/44 inhibitor) and SB20358 (p38 inhibitor) decreased NF-κB binding activity and prevented IκB-α degradation. However, we only observed a reduction in IKK-1 and IKK-2 activity with PD98059. Statins diminish NF-κB activation elicited by oxidative stress through the inhibition of IKK-1/-2, p38, and p42/44 activation. These data may help to further understand the molecular mechanisms of statins in cardiovascular disease.
Effects of KATP Channel Modulation on Myocardial Glycogen Content, Lactate, and Amino Acids in Nonischemic and Ischemic Rat Hearts
Authors: Kristiansen Steen B , Nielsen-Kudsk Jens Erik , Bøtker Hans Erik , Nielsen Torsten Toftegaard
Published: April 2005

ATP-sensitive potassium (KATP) channels are involved in the mechanisms underlying ischemic preconditioning. KATP channels open during ischemia, presumably secondary to intracellular metabolic alterations. The direct effects of KATP channel modulation on myocardial metabolism have not been studied. The aim of the present study was to investigate whether a KATP opener (diazoxide) and blocker (glibenclamide) modulates myocardial glycogen, lactate, and amino acid content before, during, and after ischemia. In isolated perfused rat hearts, we investigated the effect of diazoxide (30 μM) and glibenclamide (10 μM) administered 15 minutes before ischemia on myocardial glycogen, lactate, and amino acid content before, during, and after ischemia. Diazoxide increased left-ventricular developed pressure during reperfusion (P < 0.05) and decreased myocardial glycogen depletion (P < 0.05) and lactate accumulation (P < 0.05) during ischemia compared with the control group. Glibenclamide decreased myocardial glycogen content (P < 0.05) and increased myocardial lactate (P < 0.05) and alanine (P < 0.05) content before ischemia and reduced myocardial glycogen content after ischemia (P < 0.05) compared with control. KATP channel activation by diazoxide modulates myocardial metabolism. These findings suggest that activation of KATP channels protects against ischemia-reperfusion injury by a mechanism that involves decreased energy depletion.
Sustained Cardioprotection Afforded by A2A Adenosine Receptor Stimulation After 72 Hours of Myocardial Reperfusion
Authors: Boucher Matthieu , Wann Boubacar Pasto , Kaloustian Sevan , Massé Rachel , Schampaert Érick , Cardinal René , Rousseau Guy
Published: April 2005

This study was designed to determine whether cardioprotection afforded by A2A adenosine receptor stimulation can be sustained and to determine the effect of an A2A adenosine receptor agonist on Akt and cAMP response element binding protein (CREB) activation, as well as Hsp27 and Hsp70 protein expression in such events. The left anterior descending coronary artery was occluded for 40 minutes in anesthetized rats followed by 72 hours of reperfusion. A2A agonist (CGS21680 at 0.2 μg/kg/min) was administered for 120 minutes, starting either 5 minutes before (early) or after (late) the beginning of reperfusion. Infarct size was reduced significantly in the early compared with the control group (35.2 ± 1.9% and 52.5 ± 3.4%, respectively; P < 0.05), whereas no difference was observed with the late group (44.5 ± 7.1%). After 72 hours of reperfusion, drug administration was accompanied by Akt activation (early, 121.8 ± 17.6%; late, 118.1 ± 16.4%; P < 0.05), as well as elevated Hsp27 expression (early, 197.2 ± 27.7%; late, 203.8 ± 36.8%; P < 0.05); CREB activation and Hsp70 expression were not altered. In another set of experiments in which reperfusion was limited to 15 minutes, Akt was activated only in the early group (121.8 ± 17.6%; P < 0.05). Moreover, CREB was activated in both the early and late groups (98.4 ± 8.3% and 107.0 ± 6.5%, respectively; P < 0.05), whereas Hsp27 and Hsp70 expression were not altered. These results demonstrate that A2A adenosine receptor activation induces a sustained cardioprotection only if the therapy is instituted before reperfusion. This myocardial protection is associated by an early prosurvival Akt activation. CREB activation and Hsp27 content do not seem to be associated with cardioprotection because they are enhanced in both treated groups, suggesting indirect A2A agonist and pathology-related effects.
Analysis of Pulmonary Vascular Response to Acute Alveolar Hypoxic Challenge in Young Rabbits Subjected to Chronic Hypoxia from Birth
Authors: Baber Syed R , Li Hong , Simakajornboon Narong , Kadowitz Philip J , Ross-Ascuitto Nancy T , Ascuitto Robert J
Published: April 2005

Chronic alveolar hypoxia induces vascular changes leading to pulmonary hypertension. We investigated the role of nitric oxide synthase (NOS) on basal pulmonary artery pressure (PAP) and on changes in PAP arising from an acute alveolar hypoxic challenge (AAHC) in normoxic and chronically hypoxic young rabbits. The chronically hypoxic rabbits were raised from birth in a chamber containing a (10% O2 + 90% N2) gas mixture, whereas the normoxic rabbits were kept in room air. The age of the animals at the time of study (∼38 days) was not significantly different between the 2 groups of rabbits. The in vivo PAP was measured using a right heart catheterization technique while the rabbits were spontaneously breathing either a hyperoxic or a hypoxic gas. In the chronically hypoxic group, the AAHC (hypoxic gas) produced a modest increase in PAP. However, after intravenous administration of (100 mg/kg) of the NOS inhibitor, L-NAME (Nω−nitro-L-arginine methyl ester), a marked increase in PAP was observed when these rabbits were rechallenged with the AAHC. In contrast, in the normoxic rabbits, the AAHC produced only a small increase in PAP, even after pretreatment with L-NAME. In both groups of rabbits, L-NAME led to a significant rise in basal PAP. Using Western blot analysis, we found endothelial NOS (eNOS) protein expression to be significantly increased in pulmonary artery and right ventricular myocardium of the chronically hypoxic rabbits. These results suggest that release of nitric oxide is involved in regulating basal PAP and in modulating the hypoxia-induced pulmonary vasoconstrictor response in immature animals. Moreover, eNOS appears to undergo up-regulation as a consequence of chronic hypoxia.
Influence of Diabetes Mellitus, Hypercholesterolemia, and Their Combination on EDHF-Mediated Responses in Mice
Authors: Morikawa Keiko , Matoba Tetsuya , Kubota Hiroshi , Hatanaka Makoto , Fujiki Takako , Takahashi Shosuke , Takeshita Akira , Shimokawa Hiroaki
Published: April 2005

The endothelium synthesizes and releases several vasodilator substances, including vasodilator prostaglandins, NO, and EDHF. NO-mediated relaxations are reduced by various risk factors, such as diabetes mellitus and hypercholesterolemia. However, it remains to be elucidated whether EDHF-mediated relaxations also are reduced by those factors and their combination. In this study, we addressed this point in mice. We used small mesenteric arteries from control, diabetic (streptozotocin-induced), apolipoprotein-E-deficient (ApoE−/−), and diabetic ApoE−/− mice. In control mice, endothelium-dependent relaxations to acetylcholine were largely mediated by EDHF. This EDHF-mediated component was slightly reduced in diabetic mice, preserved in ApoE−/− mice, and markedly reduced in diabetic ApoE−/− mice with an increase in NO-mediated component and a negative contribution of indomethacin-sensitive endothelium-derived contracting factor (EDCF). Endothelium-independent relaxations to sodium nitroprusside or NS1619, a direct opener of calcium-activated K channels, were attenuated in ApoE−/− and diabetic ApoE−/− mice. Endothelium-dependent hyperpolarizations were significantly reduced in diabetic mice, preserved in ApoE−/− mice, and again markedly reduced in diabetic ApoE−/− mice. These results indicate that hypercholesterolemia alone minimally affects the EDHF-mediated relaxations, and diabetes mellitus significantly attenuated the responses, whereas their combination markedly attenuates the responses with a compensatory involvement of NO and a negative contribution of EDCF.
Morphology and feeding in tadpoles of Ceratophrys cranwelli (Anura: Leptodactylidae)
Authors: Vera Candioti M. F.
Published: April 2005

This paper provides data on the skeleton, musculature, buccal apparatus, buccopharyngeal cavity and diet of Ceratophrys cranwelli tadpoles, and attempts to contribute to the knowledge of relations between morphology and ecology in anuran larvae. Both in morphological characters and feeding habits, these tadpoles are very similar to other species within the genus. They possess many of the structural features usually found in predaceous tadpoles: strong, keratinized jaw sheaths and keratodonts, reduced buccal papillation, high values of in‐lever arm proportion and buccal floor area, well‐developed ceratohyals, and hypertrophied jaw muscles. Food sources consist of other tadpoles, microcrustaceans, larvae of insects, plant fragments, as well as rotifers and microalgae. As facultative carnivores, they are likely to play an important role in regulating the aquatic communities of the ephemeral ponds where they develop.
The impact of prolonged fasting during aestivation on the structure of the small intestine in the green‐striped burrowing frog, Cyclorana alboguttata
Authors: Cramp Rebecca L. , Franklin Craig E. , Meyer Edward A.
Published: April 2005

The effects of short‐term fasting and prolonged fasting during aestivation on the morphology of the proximal small intestine and associated organs were investigated in the green‐striped burrowing frog, Cyclorana alboguttata (Anura: Hylidae). Animals were fasted for 1 week while active or for 3–9 months during aestivation. Short‐duration fasting (1 week) had little effect on the morphology of the small intestine, whilst prolonged fasting during aestivation induced marked enteropathy including reductions in intestinal mass, length and diameter, longitudinal fold height and tunica muscularis thickness. Enterocyte morphology was also affected markedly by prolonged fasting: enterocyte cross‐sectional area and microvillous height were reduced during aestivation, intercellular spaces were visibly reduced and the prevalence of lymphocytes amongst enterocytes was increased. Mitochondria and nuclei were also affected by 9 months of aestivation with major disruptions to mitochondrial cristae and increased clumping of nuclear material and increased infolding of the nuclear envelope. The present study demonstrates that the intestine of an aestivating frog responds to prolonged food deprivation during aestivation by reducing in size, presumably to reduce the energy expenditure of the organ.
Two new species of litter‐dwelling Metagonia spiders (Araneae, Pholcidae) document both rapid and slow genital evolution
Authors: Huber Bernhard A. , Rheims Cristina A. , Brescovit Antonio D.
Published: April 2005

The observation that genitalia, rather than other characters, are useful in distinguishing species has resulted in the statement that genitalia evolve relatively rapidly. In this paper we claim that relatively rapid evolution of genitalia may often be restricted to the shapes, numbers, and sizes of individual structures. In contrast, the more basic pattern, including the presence or absence of structures and their interrelationships (the bauplan), does not seem to evolve more rapidly than other (nongenital) aspects of morphology. We document this idea by contrasting two litter‐dwelling pholcid species, Metagonia petropolis sp. n. and M. paranapiacaba sp. n., with their mostly leaf‐dwelling congeners. Significant differences occur with regard to nongenital aspects of morphology as well as shapes of individual genital structures, but the bauplan of their genitalia is basically the same.
Ciliary sieving and active ciliary response in capture of particles by suspension‐feeding brachiopod larvae
Authors: Strathmann R. R.
Published: April 2005

Larvae of a brachiopod, Glottidia pyramidata, used at least two ciliary mechanisms to capture algal cells upstream from the lateral band of cilia that produces a feeding/swimming current. (1) Filtration: the larvae retained algal cells on the upstream (frontal) side of a sieve composed of a row of stationary laterofrontal cilia. Movement of the laterofrontal cilia could not be observed during capture or rejection of particles, but the laterofrontal cilia can bend toward the beating lateral cilia, a possible mechanism for releasing rejected particles from the ciliary sieve. (2) Localized changes of ciliary beat: the larvae may also concentrate particles by a local change in beat of lateral cilia in response to particles. The evidence is that the beat of lateral cilia changed coincident with captures of algal cells and that captured particles moved on paths consistent with a current redirected toward the frontal side of the tentacle by an induced local reversal of the lateral cilia. The change of beat of lateral cilia could have been an arrest rather than a reversal of ciliary beat, however. The similar ciliary bands in adult and larval lophophorates (brachiopods, phoronids, and bryozoans) suggest that these animals share a range of ciliary behaviours. The divergent accounts of ciliary feeding of lophophorates could be mostly the result of different authors observing different aspects of ciliary feeding.
Egg envelopes of Baetis rhodani and Cloeon dipterum (Ephemeroptera, Baetidae): a comparative analysis between an oviparous and an ovoviviparous species
Authors: Gaino E. , Rebora M.
Published: April 2005

A comparative ultrastructural investigation on the eggshell (vitelline and chorionic envelopes) has been carried out in the nymphs of two mayfly species encompassed into the Baetidae, namely Baetis rhodani and Cloeon dipterum. During oocyte differentiation in the meroistic telotrophic ovarioles, gametes are connected to discrete nurse cells by trophic cords. In B. rhodani, each ovariole contains several eggs arranged in sequence, whereas in C. dipterum each contains a single egg. Follicle cells are competent for vitelline and chorionic envelope synthesis. Baetis rhodani is an oviparous species and the chorion is fairly thick, formed by an alveolate endochorion and a fibrillar exochorion delimited by a honey‐comb roof. Cloeon dipterum stands out among Ephemeroptera for being ovoviviparous. In B. rhodani, ovulation starts in the older nymphs with dark wing‐pads, whereas in C. dipterum choriogenesis ends in the imaginal stage. Here the chorion is very thin and laid eggs hatch almost immediately, allowing the larvulae to move out. The maturation of a single egg per ovariole is synchronized with the achievement of the adult stage. The acquisition of ovoviviparity has led to remarkable changes in the ovariole organization along with a simplification of the eggshell structure.
Expression of RUNX3 protein in human lung adenocarcinoma: Implications for tumor progression and prognosis
Authors: Araki Kunio , Osaki Mitsuhiko , Nagahama Yumi , Hiramatsu Toshiki , Nakamura Hiroshige , Ohgi Shigetsugu , Ito Hisao
Published: April 2005

Runt‐related transcription factor 3 belongs to the runt domain family of transcription factors that play a pivotal role during normal tissue development and tumorigenesis in several organs. We directed our attention to the expression of RUNX3 protein in human lung AC and non‐neoplastic lung tissues, comparing the results with clinicopathological profiles. We evaluated the expression of RUNX3 protein in 17 pairs of lung AC and non‐neoplastic lung tissue. Furthermore, 98 lung AC were studied to examine the frequency of RUNX3‐positive cells. Western blot analysis showed a single band at 45 kDa in all 17 AC and non‐neoplastic tissues. Immunohistochemistry revealed immunoreactivity in alveolar type II pneumocytes or Clara cells. RUNX3 was expressed more frequently in the carcinomas with a BAC component than in those without (P < 0.01). Lower RUNX3 levels were associated with poorly differentiated types (P = 0.049). The five‐year survival rate was significantly higher in the 50 patients with higher levels of RUNX3 expression than in the 48 patients with lower levels (P = 0.027). The expression of RUNX3 protein in lung AC might play a pivotal role in tumor progression and patients’ survival. (Cancer Sci 2005; 96: 227–231)
N‐acetyl‐cysteine enhances growth in BCR‐ABL‐transformed cells
Authors: Zhang QiGuo , Tsukahara Fujiko , Maru Yoshiro
Published: April 2005

N‐acetyl‐cysteine (NAC) has been reported to have anticancer properties such as counteractions against mutagens and prevention of tumor progression by scavenging reactive oxygen species (ROS). However, here we report that NAC can enhance the anchorage‐independent growth of cells transformed by activated ABL tyrosine kinases or Ras. This effect was not dependent on loss of focal adhesion kinase activation. NAC rescued cell growth that was suppressed by heat shock protein (Hsp) 90 inhibitors possibly by chemical modification of their quinone moiety. NAC rendered Rat1/BCR‐ABL cells resistance to a Ras inhibitor manumycin in soft agar colony formation. In the absence of Hsp90 inhibitors, NAC stimulated the activation of MAP kinase in BCR‐ABL‐transformed but not in the parental Rat1 cells. We propose that NAC should be used carefully in cancer treatment. (Cancer Sci 2005; 96: 240 –244)
Influence of atrazine administration and reduction of calorie intake on prostate carcinogenesis in probasin/SV40 T antigen transgenic rats
Authors: Kandori Hitoshi , Suzuki Shugo , Asamoto Makoto , Murasaki Toshiya , Mingxi Tang , Ogawa Kumiko , Shirai Tomoyuki
Published: April 2005

Atrazine, which has been used worldwide as a pesticide, is now known to exert endocrine disrupting (antiandrogenic) effects in mammals. In this study, modifying effects of dietary feeding of 500 and 1000 p.p.m. atrazine on the development of androgen‐dependent prostate cancer were investigated using male probasin/SV40 T antigen transgenic (TG) rats. As administration of atrazine has now been identified as causing a decrease in bodyweight, a dietary‐restricted TG rat group was also included in order to elucidate the influence of reduction of calorie intake per se on the development of prostate cancer. At week 13, almost the entire lobes of the prostate were occupied with tumor lesions, with no clear intergroup differences in the incidences and multiplicities. Therefore, morphometrical assessment ratios of the prostate epithelial area to the whole prostate tissue area were evaluated. The ratio in the lateral lobe of the 1 000 p.p.m. atrazine‐treated group was significantly decreased, and there was a tendency to decrease in the ratios in the dorsal lobe of the atrazine‐treated groups. However, dietary restriction itself without atrazine treatment caused the same reduction to a similar or greater extent. Testosterone levels were not affected by atrazine administration or dietary restriction. Our results indicate that the observed atrazine‐related suppression of prostate carcinogenesis was probably caused by the decrease in calorie intake, rather than by atrazine‐related endocrine disruption. (Cancer Sci 2005; 96: 221–226)
Why are we waiting? The demography of adoption for children of black, Asian and black mixed parentage in England
Authors: Frazer Lesley , Selwyn Julie
Published: April 2005

The known shortage of adopters for children of black, Asian and black mixed parentage poses many dilemmas for practitioners, not least because of the potentially damaging consequences of delay while placements are sought. Drawing on a study of agency policy and practice in the recruitment of a larger, more diverse pool of adopters, this paper explores the demography of adoption for children of black, Asian and black mixed parentage. The paper suggests that the adoption prospects of children of some ethnic and religious groups may be affected by the young age structures of their populations. The age profiles and presenting needs of looked after children also vary between ethnic groups, putting some groups at a relatively greater disadvantage in terms of their adoption chances. At the same time, the paper considers the environmental and family factors that may affect the recruitment of a more diverse pool of adopters, and highlights the difficulties of achieving a balance between adopters’ expectations and the needs of waiting children. It concludes that more culturally sensitive and proactive recruitment strategies are needed, together with targeted, creative approaches to meet the placement needs of those children of black, Asian or mixed parentage who currently wait longest.