bluuebunny/crossref_metadata_2025 huggingface dataset:
DEVELOPMENT OF SAMPLE PREPARATION METHOD FOR ENGINE LUBRICATING OIL ANALYSIS USING IN-AIR PIXE
Authors: SAITOH KATSUMI , ISHIKAWA TAKAHIRO , ISO HIROYUKI , KONISHI TERUAKI , IMASEKI HITOSHI , HASEGAWA SHUICHI , FUSHIMI AKIHIRO , KOBAYASHI SHINJI , TANABE KIYOSHI
Published: October 2008

We originally developed a preparation method for samples of automobile engine lubricating oil (liquid sample) specifically designed for in-air particle induced X-ray emission (PIXE) analysis with Helium ions. In the developed preparation method, target samples were fixed by making the oil sample sandwiches with 1% collodion solution based ethanol. With this analytical method, elements such as Al , Si , P , S , Cl , Ca and Zn can be detected from the oil samples, while Si , P , S , Ca and Zn were the elemental components of the oil additives.
ADAPTIVE SYNCHRONIZATION OF UNCERTAIN RÖSSLER SYSTEM BASED ON PARAMETER IDENTIFICATION
Authors: WANG XINGYUAN , LI XINGUANG
Published: October 2008

Assuming the Rössler system as a reference, this paper studies two cases of chaotic synchronization of a pair of (master and slave) systems: one with fully uncertain parameters for both, the other where the master system has fixed given parameters while the slave system is endowed with uncertain parameters. The respective adaptive controller based on parameter identification is then designed, according to the Lyapunov stability theorem. Then, it is proved that the two controllers are capable of making the two (identical) Rössler systems asymptotically synchronized. Numerical simulation results further testify the efficiency of controllers.
EFFECTS OF AN ENDOSCOPE AND AN ELECTRICALLY CONDUCTING THIRD GRADE FLUID ON PERISTALTIC MOTION
Authors: HAYAT T. , MOMONIAT E. , MAHOMED F. M.
Published: October 2008

This investigation deals with the influence of an inserted endoscope and a magnetohydrodynamic (MHD) third grade fluid on the peristaltic flow under zero Reynolds number and long wavelength approximations. A uniform magnetic field is applied transversely to the flow. The mathematical model considers an incompressible fluid through the gap between concentric uniform tubes, such that the inner tube is rigid and the outer tube travels down its wall. The governing non-linear equation has been modeled and then solved for arbitrary values of Deborah number. The effect of the Hartmann number, Deborah number, volume flow rate, radius ratio and the various parameters entering into the problem are discussed on the velocity components, axial pressure gradient, pressure rise and frictional forces on the inner and outer tubes.
LATTICE MISFIT MEASUREMENT IN INCONEL 625 BY X-RAY DIFFRACTION TECHNIQUE
Authors: SARKAR A. , MUKHERJEE P. , BARAT P. , JAYAKUMAR T. , MAHADEVAN S. , RAI SANJAY K.
Published: October 2008

Determination of lattice misfit and microstructural parameters of the coherent precipitates in Ni based alloy Inconel-625 is a challenging problem as the diffraction peaks of the precipitate and the matrix are completely overlapping. X-ray Diffraction Line Profile Analysis (XRDLPA) has been used to characterize the bulk samples of Inconel 625 at different heat-treated conditions to determine the lattice parameters of the parent phase and also the coherent precipitates by the separation of the overlapping peaks. The lattice misfits of the coherent precipitates with the matrix and their microstructural parameters like size and strain have also been determined.
ADAPTIVE ROBUST SYNCHRONIZATION FOR A CLASS OF DIFFERENT UNCERTAIN CHAOTIC SYSTEMS
Authors: WANG XINGYUAN , WANG MINGJUN
Published: October 2008

This paper addresses the adaptive synchronization problem of a class of different uncertain chaotic systems. A general adaptive robust controller and parameters update rule are designed. It is proved theoretically that the controller and update rule can make the drive-response systems with different structures asymptotically synchronized, and change the unknown parameters to constants when noise exists. When the drive system is certain, the unknown parameters of the response system can be updated to the predicted values. The results of numerical simulations show the effectiveness of the adaptive controller.
INFLUENCE OF A TWO-DIMENSIONAL PERIODIC DIELECTRIC BACKGROUND ON THE PHOTONIC BAND GAP IN COMPLEX HEXAGONAL LATTICE PHOTONIC CRYSTALS
Authors: ZHANG YAN , SHI JUN-JIE
Published: October 2008

A complex hexagonal lattice photonic crystal with a two-dimensional (2D) periodic dielectric background is proposed. The photonic band modulation effects due to the 2D periodic dielectric background are investigated. We find that the position and width of the complete photonic band gap (PBG) sensitively depend on the dielectric constants of the 2D periodic dielectric background. The radii of the two alternating air holes have significant influence on the relative width of the complete PBG.
VORTEX LATTICE STATE OF A SUPERFLUID FERMI GAS IN THE UNITARY REGION
Authors: GAO MENG , YIN LAN
Published: October 2008

In this paper, we study the structure of vortex lattices in a trapped superfluid Fermi gas in the unitary region near the superfluid transition temperature. A phenomenological approach based on the Ginzburg-Landau theory is used. Two types of stable triangular vortex lattices are found numerically at the same rotation frequency. In type (A), the trap center is occupied by a vortex; in type (B), there are three vortices closest to the trap center which is unoccupied. The lattice structures at different rotation frequencies and temperatures are analyzed. The vortex density increases linearly with the rotation frequency, very close to the analytical estimation. The superfluid and type-(B) vortex lattice do not disappear together. At high rotation frequencies, the vortex lattice disappears, but there exists a localized superfluid state near the trap center. The superfluid vanishes at a critical rotation frequency consistent with the theory for the upper critical magnetic field of type-II superconductors.
ANALYTICAL COMPARISON BETWEEN THE HOMOTOPY PERTURBATION METHOD AND VARIATIONAL ITERATION METHOD FOR DIFFERENTIAL EQUATIONS OF FRACTIONAL ORDER
Authors: ODIBAT ZAID , MOMANI SHAHER
Published: October 2008

Comparison of homotopy perturbation method (HPM) and variational iteration method (VIM) is made, revealing that the two methods can be used as alternative and equivalent methods for obtaining analytic and approximate solutions for different types of differential equations of fractional order. Furthermore, the former is more general and powerful than the latter. Numerical results show that the two approaches are easy to implement and accurate when applied to differential equations of fractional order.
SYNTHESIS OF ZIRCONIUM OXYNITRIDE (ZrON) NANOCOMPOSITE FILMS ON ZIRCONIUM SUBSTRATE BY DENSE PLASMA FOCUS DEVICE
Authors: KHAN I. A. , HASSAN M. , AHMAD R. , MURTAZA G. , ZAKAULLAH M. , RAWAT R. S. , LEE P.
Published: October 2008

Nanocrystalline zirconium nitride/oxide "zirconium oxynitride" nanocomposite film is deposited on zirconium substrate by dense plasma focus device at room temperature. X-ray diffraction of irradiated samples reveals that different phases ( ZrN , Zr3N4and ZrO2) of zirconium nitride and zirconium oxide are evolved. The crystallinity of these phases depends on axial positions as well as ion energy flux. Scanning electron microscopy shows that the deposited film is more compact at lower axial position, which is due to higher ion energy flux. Energy dispersive X-rays spectroscopy shows that the presence of nitrogen concentration decreases by increasing the axial position. Maximum microhardness value for the deposited layer is found to be 7200 ± 12 MPa at 10 gram imposed load.
THE PHASE AND INVERSION PROBLEM FOR MULTIPLY SCATTERED ELECTRONS
Authors: ALLEN L. J. , MARTIN A. V.
Published: October 2008

The inversion of scattering data to obtain the structure of a thin specimen illuminated by electrons is discussed. The inversion problem has two aspects, the reconstruction of one or more exit surface wave functions and the subsequent retrieval of the projected structure of the specimen. The second step is complicated by the fact that electrons interact strongly with matter and multiple scattering complicates the inversion problem unless the specimen is very thin, particularly in the case of crystalline specimens.
DESIGN OF SEMICONDUCTOR HETEROSTRUCTURES VIA INVERSE QUANTUM SCATTERING
Authors: BOTHA A. E.
Published: October 2008

The use of one-dimensional inverse quantum scattering theory for the design of semiconductor heterostructures is reviewed within the contexts of (i) the single-band constant effective mass model (ii) the single-band variable effective mass model and (iii) the multi-band pseudopotential model. As a fourth application a different inverse method is developed for the multi-band k · p model. This method is based on the one-dimensional coupled-channel Marchenko method. Preliminary numerical results are presented for a two-band k · p model of an InAs / GaSb / InAs single quantum well in which the strength of the interband coupling is approximately constant.
REMARK ON ESTIMATE OF A POTENTIAL IN TERMS OF EIGENVALUES OF THE STURM–LIOUVILLE OPERATOR
Authors: KOROTYAEV EVGENY
Published: October 2008

We consider the Sturm–Liouville operator on the unit interval. We obtain two-sided a priori estimates of potential in terms of Dirichlet and Neumann eigenvalues and eigenvalues for 2 types of mixed boundary conditions.
USING MIXED DATA IN THE INVERSE SCATTERING PROBLEM
Authors: LASSAUT M. , LARSEN S. Y. , SOFIANOS S. A. , WALLET J. C.
Published: October 2008

Consider the fixed-ℓ inverse scattering problem. We show that the zeros of the regular solution of the Schrödinger equation, rn(E), which are monotonic functions of the energy, determine a unique potential when the domain of the energy is such that the rn(E) range from zero to infinity. This suggests that the use of the mixed data of phase-shifts {δ(ℓ0, k), k ≥ k0} ∪ {δ(ℓ, k0), ℓ ≥ ℓ0}, for which the zeros of the regular solution are monotonic in both domains, and range from zero to infinity, offers the possibility of determining the potential in a unique way.
SEMI-ANALYTIC EQUATIONS TO THE COX–THOMPSON INVERSE SCATTERING METHOD AT FIXED ENERGY FOR SPECIAL CASES
Authors: PÁLMAI TAMÁS , HORVÁTH MIKLÓS , APAGYI BARNABÁS
Published: October 2008

Solution of the Cox–Thompson inverse scattering problem at fixed energy1–3 is reformulated resulting in semi-analytic equations. The new set of equations for the normalization constants and the nonphysical (shifted) angular momenta are free of matrix inversion operations. This simplification is a result of treating only the input phase shifts of partial waves of a given parity. Therefore, the proposed method can be applied for identical particle scattering of the bosonic type (or for certain cases of identical fermionic scattering). The new formulae are expected to be numerically more efficient than the previous ones. Based on the semi-analytic equations an approximate method is proposed for the generic inverse scattering problem, when partial waves of arbitrary parity are considered.
TWO- AND THREE-ALPHA SYSTEMS WITH NONLOCAL POTENTIAL
Authors: PAPP Z. , MOSZKOWSKI S.
Published: October 2008

Two body data alone cannot determine the potential uniquely, one needs three-body data as well. A method is presented here which simultaneously fits local or nonlocal potentials to two-body and three-body observables. The interaction of composite particles, due to the Pauli effect and the indistinguishability of the constituent particles, is genuinely nonlocal. As an example, we use a Pauli-correct nonlocal fish-bone type optical model for the α – α potential and derive the fitting parameters such that it reproduces the two-α and three-α experimental data.
SOME RESULTS ON INVERSE SCATTERING
Authors: RAMM A. G.
Published: October 2008

A review of some of the author's results in the area of inverse scattering is given. The following topics are discussed: (1) Property C and applications, (2) Stable inversion of fixed-energy 3D scattering data and its error estimate, (3) Inverse scattering with “incomplete” data, (4) Inverse scattering for inhomogeneous Schrödinger equation, (5) Krein's inverse scattering method, (6) Invertibility of the steps in Gel'fand–Levitan, Marchenko, and Krein inversion methods, (7) The Newton–Sabatier and Cox–Thompson procedures are not inversion methods, (8) Resonances: existence, location, perturbation theory, 9) Born inversion as an ill-posed problem, (10) Inverse obstacle scattering with fixed-frequency data, (11) Inverse scattering with data at a fixed energy and a fixed incident direction, (12) Creating materials with a desired refraction coefficient and wave-focusing properties.
SOME SURPRISES AND PARADOXES REVEALED BY INVERSE PROBLEM APPROACH AND NOTION ABOUT QUALITATIVE SOLUTIONS OF SCHRÖDINGER EQUATIONS “IN MIND”
Authors: ZAKHARIEV B. N. , CHABANOV V. M.
Published: October 2008

It was an important examination to give a review talk at the previous Conference on Inverse Quantum Scattering (1996, Lake Balaton) about computer visualization of this science in front of its fathers — creators, B. M. Levitan and V. A. Marchenko. We have achieved a new understanding that the discovered main rules of transformations of a single wave function bump, e.g., for the ground bound states of one dimensional quantum systems are applicable to any state of any potential with arbitrary number of bumps from finite to unlimited ones as scattering states and bound states embedded into continuum. It appeared that we need only to repeat the rule mentally the necessary number of times. That uttermost simplification and unification of physical notion of spectral, scattering and decay control for any potential have got an obligatory praise from B. M. Levitan at the conference and was a mighty stimulus for our further research After that we have written both Russian (2002) and improved English editions of “Submissive Quantum Mechanics. New Status of the Theory in Inverse Problem Approach”1 (appeared at the very end of 2007). This book was written for correction of the present defect in quantum education throughout the world. Recently the quantum IP intuition helped us to discover a new concept of permanent wave resonance with potential spatial oscillations.2 This means the constant wave swinging frequency on the whole energy intervals of spectral forbidden zones destroying physical solutions and deepening the theory of waves in periodic potentials. It also shows the other side of strengthening the fundamentally important magic structures. A ‘new language’ of wave bending will be presented to enrich our quantum intuition, e.g., the paradoxical effective attraction of barriers and repulsion of wells in multichannel systems, etc.
Sex-Based Cardiac Physiology
Authors: Luczak Elizabeth D. , Leinwand Leslie A.
Published: October 2008

Biological sex plays an important role in normal cardiac physiology as well as in the heart's response to cardiac disease. Women generally have better cardiac function and survival than do men in the face of cardiac disease; however, this sex difference is lost when comparing postmenopausal women with age-matched men. Animal models of cardiac disease mirror what is seen in humans. Sex steroid hormones contribute significantly to sex-based differences in cardiac disease outcomes. Estrogen is generally considered to be cardioprotective, whereas testosterone is thought to be detrimental to heart function. Environmental estrogen-like molecules, such as phytoestrogens, can also affect cardiac physiology in both a positive and a negative manner.
Comparative Social Cognition
Authors: Emery Nathan J. , Clayton Nicola S.
Published: October 2008

Theory of mind is said to be uniquely human. Is this statement justified? Thirty years of research on a variety of species has produced differences in opinion, from unequivocal positive evidence to no evidence at all for mental attribution in animals. Our review concludes that animals are excellent ethologists, but on the whole, poor psychologists. Those studies that we believe present a good case for mental attribution all possess high ecological validity, including studies on food competition by chimpanzees and cache-protection strategies by corvids. Even though the current focus of research on prediction rather than explanation may be misplaced, we believe the field is now in a strong position to discover what animals really know about their fellow beings, be it based on simple associations, behavior reading, mind reading, or something else.
Role of NADH/NAD+ transport activity and glycogen store on skeletal muscle energy metabolism during exercise: in silico studies
Authors: Li Yanjun , Dash Ranjan K. , Kim Jaeyeon , Saidel Gerald M. , Cabrera Marco E.
Published: October 2008

Skeletal muscle can maintain ATP concentration constant during the transition from rest to exercise, whereas metabolic reaction rates may increase substantially. Among the key regulatory factors of skeletal muscle energy metabolism during exercise, the dynamics of cytosolic and mitochondrial NADH and NAD+ have not been characterized. To quantify these regulatory factors, we have developed a physiologically based computational model of skeletal muscle energy metabolism. This model integrates transport and reaction fluxes in distinct capillary, cytosolic, and mitochondrial domains and investigates the roles of mitochondrial NADH/NAD+ transport (shuttling) activity and muscle glycogen concentration (stores) during moderate intensity exercise (60% maximal O2 consumption). The underlying hypothesis is that the cytosolic redox state (NADH/NAD+) is much more sensitive to a metabolic disturbance in contracting skeletal muscle than the mitochondrial redox state. This hypothesis was tested by simulating the dynamic metabolic responses of skeletal muscle to exercise while altering the transport rate of reducing equivalents (NADH and NAD+) between cytosol and mitochondria and muscle glycogen stores. Simulations with optimal parameter estimates showed good agreement with the available experimental data from muscle biopsies in human subjects. Compared with these simulations, a 20% increase (or ∼20% decrease) in mitochondrial NADH/NAD+ shuttling activity led to an ∼70% decrease (or ∼3-fold increase) in cytosolic redox state and an ∼35% decrease (or ∼25% increase) in muscle lactate level. Doubling (or halving) muscle glycogen concentration resulted in an ∼50% increase (or ∼35% decrease) in cytosolic redox state and an ∼30% increase (or ∼25% decrease) in muscle lactate concentration. In both cases, changes in mitochondrial redox state were minimal. In conclusion, the model simulations of exercise response are consistent with the hypothesis that mitochondrial NADH/NAD+ shuttling activity and muscle glycogen stores affect primarily the cytosolic redox state. Furthermore, muscle lactate production is regulated primarily by the cytosolic redox state.
Visualizing the temporal effects of vasoconstrictors on PKC translocation and Ca2+signaling in single resistance arterial smooth muscle cells
Authors: Nelson Carl P. , Willets Jonathon M. , Davies Noel W. , Challiss R. A. John , Standen Nicholas B.
Published: October 2008

Arterial smooth muscle (ASM) contraction plays a critical role in regulating blood distribution and blood pressure. Vasoconstrictors activate cell surface receptors to initiate signaling cascades involving increased intracellular Ca2+concentration ([Ca2+]i) and recruitment of protein kinase C (PKC), leading to ASM contraction, though the PKC isoenzymes involved vary between different vasoconstrictors and their actions. Here, we have used confocal microscopy of enhanced green fluorescence protein (eGFP)-labeled PKC isoenzymes to visualize PKC translocation in primary rat mesenteric ASM cells in response to physiological vasoconstrictors, with simultaneous imaging of Ca2+signaling. Endothelin-1, angiotensin II, and uridine triphosphate all caused translocation of each of the PKC isoenzymes α, δ, and ε; however, the kinetics of translocation varied between agonists and PKC isoenzymes. Translocation of eGFP-PKCα mirrored the rise in [Ca2+]i, while that of eGFP-PKCδ or -ε occurred more slowly. Endothelin-induced translocation of eGFP-PKCε was often sustained for several minutes, while responses to angiotensin II were always transient. In addition, preventing [Ca2+]iincreases using 1,2-bis-( o-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid tetra-(acetoxymethyl) ester prevented eGFP-PKCα translocation, while eGFP-PKCδ translocated more rapidly. Our results suggest that PKC isoenzyme specificity of vasoconstrictor actions occurs downstream of PKC recruitment and demonstrate the varied kinetics and complex interplay between Ca2+and PKC responses to different vasoconstrictors in ASM.
Genome-wide RNAi screen and in vivo protein aggregation reporters identify degradation of damaged proteins as an essential hypertonic stress response
Authors: Choe Keith P. , Strange Kevin
Published: October 2008

The damaging effects of hypertonic stress on cellular proteins are poorly defined, and almost nothing is known about the pathways that detect and repair hypertonicity-induced protein damage. To begin addressing these problems, we screened ∼19,000 Caenorhabditis elegans genes by RNA interference (RNAi) feeding and identified 40 that are essential for survival during acute hypertonic stress. Half (20 of 40) of these genes encode proteins that function to detect, transport, and degrade damaged proteins, including components of the ubiquitin-proteasome system, endosomal sorting complexes, and lysosomes. High-molecular-weight ubiquitin conjugates increase during hypertonic stress, suggesting a global change in the ubiquitinylation state of endogenous proteins. Using a polyglutamine-containing fluorescent reporter, we demonstrate that cell shrinkage induces rapid protein aggregation in vivo and that many of the genes that are essential for survival during hypertonic stress function to prevent accumulation of aggregated proteins. High levels of urea, a strong protein denaturant, do not cause aggregation, suggesting that factors such as macromolecular crowding also contribute to protein aggregate formation during cell shrinkage. Acclimation of C. elegans to mild hypertonicity dramatically increases the osmotic threshold for protein aggregation, demonstrating that protein aggregation-inhibiting pathways are activated by osmotic stress. Our studies demonstrate that hypertonic stress induces protein damage in vivo and that detection and degradation of damaged proteins are essential mechanisms for survival under hypertonic conditions.
Inhibition of Na+/H+exchanger enhances low pH-induced L-selectin shedding and β2-integrin surface expression in human neutrophils
Authors: Kaba Nubia K. , Schultz Joanne , Law Foon-Yee , Lefort Craig T. , Martel-Gallegos Guadalupe , Kim Minsoo , Waugh Richard E. , Arreola Jorge , Knauf Philip A.
Published: October 2008

Ischemia-reperfusion injury is a common pathological occurrence causing tissue damage in heart attack and stroke. Entrapment of neutrophils in the vasculature during ischemic events has been implicated in this process. In this study, we examine the effects that lactacidosis and consequent reductions in intracellular pH (pHi) have on surface expression of adhesion molecules on neutrophils. When human neutrophils were exposed to pH 6 lactate, there was a marked decrease in surface L-selectin (CD62L) levels, and the decrease was significantly enhanced by inclusion of Na+/H+exchanger (NHE) inhibitor 5-( N, N-hexamethylene)amiloride (HMA). Similar effects were observed when pHiwas reduced while maintaining normal extracellular pH, by using an NH4Cl prepulse followed by washes and incubation in pH 7.4 buffer containing NHE inhibitors [HMA, cariporide, or 5-( N, N-dimethyl)amiloride (DMA)]. The amount of L-selectin shedding induced by different concentrations of NH4Cl in the prepulse correlated with the level of intracellular acidification with an apparent p K of 6.3. In contrast, β2-integrin (CD11b and CD18) was only slightly upregulated in the low-pHicondition and was enhanced by NHE inhibition to a much lesser extent. L-selectin shedding was prevented by treating human neutrophils with inhibitors of extracellular metalloproteases (RO-31-9790 and KD-IX-73-4) or with inhibitors of intracellular signaling via p38 MAP kinase (SB-203580 and SB-239063), implying a transmembrane effect of pHi. Taken together, these data suggest that the ability of NHE inhibitors such as HMA to reduce ischemia-reperfusion injury may be related to the nearly complete removal of L-selectin from the neutrophil surface.
Measuring ion transport activities in Xenopus oocytes using the ion-trap technique
Authors: Blanchard Maxime G. , Longpré Jean-Philippe , Wallendorff Bernadette , Lapointe Jean-Yves
Published: October 2008

The ion-trap technique is an experimental approach allowing measurement of changes in ionic concentrations within a restricted space (the trap) comprised of a large-diameter ion-selective electrode apposed to a voltage-clamped Xenopus laevis oocyte. The technique is demonstrated with oocytes expressing the Na+/glucose cotransporter (SGLT1) using Na+- and H+-selective electrodes and with the electroneutral H+/monocarboxylate transporter (MCT1). In SGLT1-expressing oocytes, bath substrate diffused into the trap within 20 s, stimulating Na+/glucose influx, which generated a measurable decrease in the trap Na+ concentration ([Na+]T) by 0.080 ± 0.009 mM. Membrane hyperpolarization produced a further decrease in [Na+]T, which was proportional to the increased cotransport current. In a Na+-free, weakly buffered solution (pH 5.5), H+ drives glucose transport through SGLT1, and this was monitored with a H+-selective electrode. Proton movements can also be clearly detected on adding lactate to an oocyte expressing MCT1 (pH 6.5). For SGLT1, time-dependent changes in [Na+]T or [H+]T were also detected during a membrane potential pulse (150 ms) in the presence of substrate. In the absence of substrate, hyperpolarization triggered rapid reorientation of SGLT1 cation binding sites, accompanied by cation capture from the trap. The resulting change in [Na+]T or [H+]T is proportional to the pre-steady-state charge movement. The ion-trap technique can thus be used to measure steady-state and pre-steady-state transport activities and provides new opportunities for studying electrogenic and electroneutral ion transport mechanisms.
Effect of ethanol on hydrogen peroxide-induced AMPK phosphorylation
Authors: Liangpunsakul Suthat , Wou Sung-Eun , Zeng Yan , Ross Ruth A. , Jayaram Hiremagalur N. , Crabb David W.
Published: October 2008

AMP-activated protein kinase (AMPK) responds to oxidative stress. Previous work has shown that ethanol treatment of cultured hepatoma cells and of mice inhibited the activity of AMPK and reduced the amount of AMPK protein. Ethanol generates oxidative stress in the liver. Since AMPK is activated by reactive oxygen species, it seems paradoxical that ethanol would inhibit AMPK in the hepatoma cells. In an attempt to understand the mechanism whereby ethanol inhibits AMPK, we studied the effect of ethanol on AMPK activation by exogenous hydrogen peroxide. The effects of ethanol, hydrogen peroxide, and inhibitors of protein phosphatase 2A (PP2A) [either okadaic acid or PP2A small interference RNA (siRNA)] on AMPK phosphorylation and activity were examined in rat hepatoma cells (H4IIEC3) and HeLa cells. In H4IIEC3 cells, hydrogen peroxide (H2O2, 1 mM) transiently increased the level of phospho-AMPK to 1.5-fold over control ( P < 0.05). Similar findings were observed in HeLa cells, which do not express the upstream AMPK kinase, LKB1. H2O2 markedly increased the phosphorylation of LKB1 in H4IIEC3 cells. Ethanol significantly inhibited the phosphorylation of PKC-ζ, LKB1, and AMPK caused by exposure to H2O2. This inhibitory effect of ethanol required its metabolism. More importantly, the inhibitory effects of ethanol on H2O2-induced AMPK phosphorylation were attenuated by the presence of the PP2A inhibitor, okadaic acid, or PP2A siRNA. The inhibitory effect of ethanol on AMPK phosphorylation is exerted through the inhibition of PKC-ζ and LKB1 phosphorylation and the activation of PP2A.
Changes in hemodynamic and neurohumoral control cause cardiac damage in one-kidney, one-clip hypertensive mice
Authors: Borges Giulianna R. , Salgado Helio C. , Silva Carlos Alberto A. , Rossi Marcos A. , Prado Cibele M. , Fazan Rubens
Published: October 2008

Sympathovagal balance and baroreflex control of heart rate (HR) were evaluated during the development (1 and 4 wk) of one-kidney, one-clip (1K1C) hypertension in conscious mice. The development of cardiac hypertrophy and fibrosis was also examined. Overall variability of systolic arterial pressure (AP) and HR in the time domain and baroreflex sensitivity were calculated from basal recordings. Methyl atropine and propranolol allowed the evaluation of the sympathovagal balance to the heart and the intrinsic HR. Staining of renal ANG II in the kidney and plasma renin activity (PRA) were also evaluated. One and four weeks after clipping, the mice were hypertensive and tachycardic, and they exhibited elevated sympathetic and reduced vagal tone. The intrinsic HR was elevated only 1 wk after clipping. Systolic AP variability was elevated, while HR variability and baroreflex sensitivity were reduced 1 and 4 wk after clipping. Renal ANG II staining and PRA were elevated only 1 wk after clipping. Concentric cardiac hypertrophy was observed at 1 and 4 wk, while cardiac fibrosis was observed only at 4 wk after clipping. In conclusion, these data further support previous findings in the literature and provide new features of neurohumoral changes during the development of 1K1C hypertension in mice. In addition, the 1K1C hypertensive model in mice can be an important tool for studies evaluating the role of specific genes relating to dependent and nondependent ANG II hypertension in transgenic mice.
Hypertonic saline reduces neutrophil-epithelial interactions in vitro and gut tissue damage in a mouse model of colitis
Authors: Tillinger Wolfgang , McCole Declan F. , Keely Stephen J. , Bertelsen Lone S. , Wolf Paul L. , Junger Wolfgang G. , Barrett Kim E.
Published: October 2008

Transepithelial migration of polymorphonuclear neutrophils (PMN) plays a crucial role in inflammatory conditions of the intestine, such as inflammatory bowel diseases. Hypertonic saline (HS) exerts various inhibitory effects on PMN function. We hypothesized that HS could inhibit transepithelial migration of PMN and thereby prevent inflammatory events in experimental colitis. Isolated human PMN were treated with HS (40 mM), and their transmigration across a monolayer of T84epithelial cells was induced by N-formyl-methionyl-leucyl-phenylalanine. Monolayer disruption was assessed by monitoring changes in transepithelial conductance in an Ussing chamber. Colitis in mice was induced by oral administration of dextran sulfate sodium (DSS). Animals were treated with 4 or 8 ml/kg of 7.5% saline intraperitoneally two times daily for 7 days. Controls received equivalent volumes of normal saline (NS, n = 6) or no intraperitoneal treatment (DSS, n = 12). The severity of inflammation was evaluated based on disease activity index and histology score. HS treatment of PMN in vitro significantly reduced cell migration and the disruption of T84monolayers compared with untreated control cells ( n = 5, P < 0.05). This effect of HS was dose dependent. HS treatment in vivo also reduced colitis-induced gut tissue damage, as indicated by an improved histology score compared with the NS and DSS groups. We conclude that HS inhibits transepithelial migration of PMN in vitro and gut tissue damage in vivo in a mouse model of colitis. Thus HS may have clinical value to reduce PMN-mediated intestinal damage.
Liver fat, visceral adiposity, and sleep disturbances contribute to the development of insulin resistance and glucose intolerance in nondiabetic dialysis patients
Authors: Sakkas Giorgos K. , Karatzaferi Christina , Zintzaras Elias , Giannaki Christoforos D. , Liakopoulos Vassilios , Lavdas Eleftherios , Damani Eleni , Liakos Nikos , Fezoulidis Ioannis , Koutedakis Yiannis , Stefanidis Ioannis
Published: October 2008

Hemodialysis patients exhibit insulin resistance (IR) in target organs such as liver, muscles, and adipose tissue. The aim of this study was to identify contributors to IR and to develop a model for predicting glucose intolerance in nondiabetic hemodialysis patients. After a 2-h, 75-g oral glucose tolerance test (OGTT), 34 hemodialysis patients were divided into groups with normal (NGT) and impaired glucose tolerance (IGT). Indices of insulin sensitivity were derived from OGTT data. Measurements included liver and muscle fat infiltration and central adiposity by computed tomography scans, body composition by dual energy X-ray absorptiometer, sleep quality by full polysomnography, and functional capacity and quality of life (QoL) by a battery of exercise tests and questionnaires. Cut-off points, as well as sensitivity and specificity calculations were based on IR (insulin sensitivity index by Matsuda) using a receiver operator characteristics (ROC) curve analysis. Fifteen patients were assigned to the IGT, and 19 subjects to the NGT group. Intrahepatic fat content and visceral adiposity were significantly higher in the IGT group. IR indices strongly correlated with sleep disturbances, visceral adiposity, functional capacity, and QoL. Visceral adiposity, O2 desaturation during sleep, intrahepatic fat content, and QoL score fitted into the model for predicting glucose intolerance. A ROC curve analysis identified an intrahepatic fat content of >3.97% (sensitivity, 100; specificity, 35.7) as the best cutoff point for predicting IR. Visceral and intrahepatic fat content, as well as QoL and sleep seemed to be involved at some point in the development of glucose intolerance in hemodialysis patients. Means of reducing fat depots in the liver and splachnic area might prove promising in combating IR and cardiovascular risk in hemodialysis patients.
Modular control analysis of effects of chronic hypoxia on mouse heart
Authors: Calmettes Guillaume , Deschodt-Arsac Véronique , Thiaudière Eric , Muller Bernard , Diolez Philippe
Published: October 2008

Modular control analysis (MoCA; Diolez P, Deschodt-Arsac V, Raffard G, Simon C, Santos PD, Thiaudiere E, Arsac L, Franconi JM. Am J Physiol Regul Integr Comp Physiol 293: R13–R19, 2007) was applied here on perfused hearts to describe the modifications of the regulation of heart energetics induced in mice exposed to 3-wk chronic hypoxia. MoCA combines 31P-NMR spectroscopy and modular (top down) control analysis to describe the integrative regulation of energy metabolism in the intact beating heart, on the basis of two modules [ATP/phosphocreatine (PCr) production and ATP/PCr consumption] connected by the energetic intermediates. In contrast with previous results in rat heart, in which all control of contraction was on ATP demand, mouse heart energetics presented a shared control of contraction between ATP/PCr-producing and -consuming modules. In chronic hypoxic mice, the decrease in heart contractile activity and PCr-to-ATP ratio was surprisingly associated with an important and significant higher response of ATP/PCr production (elasticity) to PCr changes compared with control hearts (−10.4 vs. −2.46). By contrast, no changes were observed in ATP/PCr consumption since comparable elasticities were observed. Since elasticities determine the regulation of energetics of heart contraction, the present results show that this new parameter may be used to uncover the origin of the observed dysfunctions under chronic hypoxia conditions. Considering the decrease in mitochondrial content reported after exposure to chronic hypoxia, it appears that the improvement of ATP/PCr production response to ATP demand may be viewed as a positive adaptative mechanism. It now appears crucial to understand the very processes responsible for ATP/PCr producer elasticity toward the energetic intermediates, as well as their regulation.
The role of inhibitory heterotrimeric G proteins in the control of in vivo heart rate dynamics
Authors: Zuberi Zia , Birnbaumer Lutz , Tinker Andrew
Published: October 2008

Multiple isoforms of inhibitory Gα-subunits (Gαi1,2,3, as well as Gαo) are present within the heart, and their role in modulating pacemaker function remains unresolved. Do inhibitory Gα-subunits selectively modulate parasympathetic heart rate responses? Published findings using a variety of experimental approaches have implicated roles for Gαi2, Gαi3, and Gαoin parasympathetic signal transduction. We have compared in vivo different groups of mice with global genetic deletion of Giα1/Gαi3, Gαi2, and Gαoagainst littermate controls using implanted ECG telemetry. Significant resting tachycardia was observed in Gαi2−/−and Gαo−/−mice compared with control and Gαi1−/−/Gαi3−/−mice ( P < 0.05). Loss of diurnal heart rate variation was seen exclusively in Gαo−/−mice. Using heart rate variability (HRV) analysis, compared with littermate controls (4.02 ms2± 1.17; n = 6, Gαi2−/−) mice have a selective attenuation of high-frequency (HF) power (0.73 ms2± 0.31; n = 5, P < 0.05). Gαi1−/−/Gαi3−/−and Gαo−/−cohorts have nonsignificant changes in HF power. Gαo−/−mice have a different basal HRV signature. The observed HRV phenotype in Gαi2−/−mice was qualitatively similar to atropine (1 mg/kg)-treated controls [and mice treated with the GIRK channel blocker tertiapinQ (0.05 mg/kg)]. Maximal cardioinhibitory response to the M2-receptor agonist carbachol (0.5 mg/kg) compared with basal heart rate was attenuated in Gαi2−/−mice (0.08 ± 0.04; n = 6) compared to control (0.27 ± 0.04; n = 7 P < 0.05). Our data suggest a selective defect of parasympathetic heart rate modulation in mice with Gαi2deletion. Mice with Gαodeletion also have a defect in short-term heart rate dynamics, but this is qualitatively different to the effects of atropine, tertiapinQ, and Gαi2deletion. In contrast, Gαi1and Gαi3do not appear to be essential for parasympathetic responses in vivo.
Potential role of purinergic signaling in urinary concentration in inner medulla: insights from P2Y2 receptor gene knockout mice
Authors: Zhang Yue , Sands Jeff M. , Kohan Donald E. , Nelson Raoul D. , Martin Christopher F. , Carlson Noel G. , Kamerath Craig D. , Ge Yuqiang , Klein Janet D. , Kishore Bellamkonda K.
Published: October 2008

Osmotic reabsorption of water through aquaporin-2 (AQP2) in the inner medulla is largely dependent on the urea concentration gradients generated by urea transporter (UT) isoforms. Vasopressin (AVP) increases expression of both AQP2 and UT-A isoforms. Activation of the P2Y2 receptor (P2Y2-R) in the medullary collecting duct inhibits AVP-induced water flow. To gain further insights into the overarching effect of purinergic signaling on urinary concentration, we compared the protein abundances of AQP2 and UT-A isoforms between P2Y2-R knockout (KO) and wild-type (WT) mice under basal conditions and following AVP administration. Under basal conditions (a gel diet for 10 days), KO mice concentrated urine to a significantly higher degree, with 1.8-, 1.66-, and 1.29-fold higher protein abundances of AQP2, UT-A1, and UT-A2, respectively, compared with WT, despite comparable circulating AVP levels in both groups. Infusion of 1-desamino-8-d-arginine vasopressin (dDAVP; desmopressin; 1 ng/h sc) for 5 days resulted in 2.14-, 2.6-, and 2.22-fold higher protein abundances of AQP2, AQP3, and UT-A1, respectively, in the inner medullas of KO mice compared with WT mice. In response to acute (45 min) stimulation by AVP (0.2 unit/mouse sc), UT-A1 protein increased by 1.39- and 1.54-fold in WT and KO mice, respectively. These data suggest that genetic deletion of P2Y2-R results in increased abundances of key proteins involved in urinary concentration in the inner medulla, both under basal conditions and following AVP administration. Thus purinergic regulation may play a potential overarching role in balancing the effect of AVP on the urinary concentration mechanism.
Acceleration of polycystic kidney disease progression in cpk mice carrying a deletion in the homeodomain protein Cux1
Authors: Alcalay Neal I. , Sharma Madhulika , Vassmer Dianne , Chapman Brandon , Paul Binu , Zhou Jing , Brantley Jennifer G. , Wallace Darren P. , Maser Robin L. , Vanden Heuvel Gregory B.
Published: October 2008

Polycystic kidney diseases (PKD) are inherited as autosomal dominant (ADPKD) or autosomal recessive (ARPKD) traits and are characterized by progressive enlargement of renal cysts. Aberrant cell proliferation is a key feature in the progression of PKD. Cux1 is a homeobox gene that is related to Drosophila cut and is the murine homolog of human CDP (CCAAT Displacement Protein). Cux1 represses the cyclin kinase inhibitors p21 and p27, and transgenic mice ectopically expressing Cux1 develop renal hyperplasia. However, Cux1 transgenic mice do not develop PKD. Here, we show that a 246 amino acid deletion in Cux1 accelerates PKD progression in cpk mice. Cystic kidneys isolated from 10-day-old cpk/Cux1 double mutant mice were significantly larger than kidneys from 10-day-old cpk mice. Moreover, renal function was significantly reduced in the Cux1 mutant cpk mice, compared with cpk mice. The mutant Cux1 protein was ectopically expressed in cyst-lining cells, where expression corresponded to increased cell proliferation and apoptosis, and a decrease in expression of the cyclin kinase inhibitors p27 and p21. While the mutant Cux1 protein altered PKD progression, kidneys from mice carrying the mutant Cux1 protein alone were phenotypically normal, suggesting the Cux1 mutation modifies PKD progression in cpk mice. During cell cycle progression, Cux1 is proteolytically processed by a nuclear isoform of the cysteine protease cathepsin-L. Analysis of the deleted sequences reveals that a cathepsin-L processing site in Cux1 is deleted. Moreover, nuclear cathepsin-L is significantly reduced in both human ADPKD cells and in Pkd1 null kidneys, corresponding to increased levels of Cux1 protein in the cystic cells and kidneys. These results suggest a mechanism in which reduced Cux1 processing by cathepsin-L results in the accumulation of Cux1, downregulation of p21/p27, and increased cell proliferation in PKD.
Analysis of DNA breaks, DNA damage response, and apoptosis produced by high NaCl
Authors: Dmitrieva Natalia I. , Burg Maurice B.
Published: October 2008

We previously reported that, both in cell culture and in the renal inner medulla in vivo, elevating NaCl increased the number of DNA breaks, which persisted as long as NaCl remained high but were rapidly repaired when NaCl was lowered. Furthermore, those breaks did not induce the DNA repair protein γH2AX or cause activation of the MRN (Mre11, Rad50, Nbs1) complex. In contrast, others recently reported that high NaCl does induce γH2AX and MRN complex formation and concluded that these activities are associated with repair of the DNA (Sheen MR, Kim SW, Jung JY, Ahn JY, Rhee JG, Kwon HM, Woo SK. Am J Physiol Renal Physiol 291: F1014–F1020, 2006). The purpose of the present studies was to resolve the disparity. The important difference is that HeLa cells, which were the main subject of the later report, are much less tolerant of high NaCl than are the mIMCD3 cells, which were our main subject. mIMCD3 cells survive levels of NaCl that kill HeLa cells by apoptosis. Here we demonstrate that in both cell types raising NaCl to a level that the cells survive (higher for mIMCD3 than HeLa) increases DNA breaks without inducing γH2AX or activating the MRN complex and that the DNA breaks persist as long as NaCl remains elevated, but are rapidly repaired when it is lowered. Importantly, in both cell types, raising NaCl further to cause apoptosis activates these DNA damage response proteins and greatly fragments DNA, associated with cell death. We conclude that γH2AX induction and MRN activation in response to high NaCl are associated with apoptosis, not DNA repair.
Intermedin ameliorates vascular and renal injury by inhibition of oxidative stress
Authors: Hagiwara Makoto , Bledsoe Grant , Yang Zhi-Rong , Smith Robert S. , Chao Lee , Chao Julie
Published: October 2008

Intermedin (IMD) is a newly discovered peptide related to calcitonin gene-related peptide and adrenomedullin, and has been shown to reduce blood pressure and reactive oxygen species formation in vivo. In this study, we determined whether IMD exerts vascular and renal protection in DOCA-salt hypertensive rats by intravenous injection of adenovirus harboring the human IMD gene. Expression of human IMD was detected in the rat kidney via immunohistochemistry. IMD administration significantly lowered blood pressure, increased urine volume, and restored creatinine clearance. IMD also dramatically decreased superoxide formation and media thickness in the aorta. Vascular injury in the kidney was reduced by IMD gene delivery as evidenced by the prevention of glomerular and peritubular capillary loss. Moreover, IMD lessened morphological damage of the renal tubulointerstitium and reduced glomerular injury and hypertrophy. Attenuation of inflammatory cell accumulation in the kidney by IMD was accompanied by inhibition of p38MAPK activation and intercellular adhesion molecule 1 expression. In addition, IMD gene transfer resulted in a marked decline in myofibroblast and collagen accumulation in association with decreased transforming growth factor-β1 levels. Furthermore, IMD increased nitric oxide excretion in the urine and lowered the amount of lipid peroxidation. These results demonstrate that IMD is a powerful renal protective agent with pleiotropic effects by preventing endothelial cell loss, kidney damage, inflammation, and fibrosis in hypertensive DOCA-salt rats via inhibition of oxidative stress and proinflammatory mediator pathways.
Identification of the Plant for Upright Stance in Humans: Multiple Movement Patterns From a Single Neural Strategy
Authors: Kiemel Tim , Elahi Alexander J. , Jeka John J.
Published: October 2008

We determined properties of the plant during human upright stance using a closed-loop system identification method originally applied to human postural control by another group. To identify the plant, which was operationally defined as the mapping from muscle activation (rectified EMG signals) to body segment angles, we rotated the visual scene about the axis through the subject's ankles using a sum-of-sines stimulus signal. Because EMG signals from ankle muscles and from hip and lower trunk muscles showed similar responses to the visual perturbation across frequency, we combined EMG signals from all recorded muscles into a single plant input. Body kinematics were described by the trunk and leg angles in the sagittal plane. The phase responses of both angles to visual scene angle were similar at low frequencies and approached a difference of ∼150° at higher frequencies. Therefore we considered leg and trunk angles as separate plant outputs. We modeled the plant with a two-joint (ankle and hip) model of the body, a second-order low-pass filter from EMG activity to active joint torques, and intrinsic stiffness and damping at both joints. The results indicated that the in-phase (ankle) pattern was neurally generated, whereas the out-of-phase pattern was caused by plant dynamics. Thus a single neural strategy leads to multiple kinematic patterns. Moreover, estimated intrinsic stiffness in the model was insufficient to stabilize the plant.