bluuebunny/crossref_metadata_2025 huggingface dataset:
A LB-BASED APPROACH FOR ADAPTIVE FLOW SIMULATIONS
Authors: CROUSE BERND , RANK ERNST , KRAFCZYK MANFRED , TÖLKE JONAS
Published: March 2003

This paper presents an approach for adaptive flow simulations based on Lattice-Boltzmann (LB) models in the sense, that in addition to an a priori distribution of degrees of freedom (DOF) a dynamic modification of the computational grid (coarsening and/or refinement) in the course of the transient computation is initiated, based on the local evaluation of error indicators in order to optimize the ratio of accuracy versus absolute number of DOF. Using quadtree-based data structures, both arbitrarily formed grid interfaces of different resolutions as well as their dynamic modification are facilitated. Efficiency aspects will be discussed based on laminar two-dimensional flow simulations. The obtained results compare well to reference solutions cited in the literature and indicate the usefulness and computational efficiency of the approach.
LATTICE BOLTZMANN SIMULATION OF THE INTERFACIAL GROWTH OF THE HORIZONTAL STRATIFIED TWO-PHASE FLOW
Authors: EBIHARA KEN-ICHI , WATANABE TADASHI
Published: March 2003

The interfacial growth of the horizontal stratified two-phase flow, which is caused by the velocity difference between two phases, is simulated by the lattice Boltzmann scheme for two-phase fluid. In order to verify the validity of the interface generated by the lattice Boltzmann method, the critical velocity difference that cause the interfacial instability and growth is measured in 2D and 3D for several wave numbers. The measurement is nearly agreement with the analysis of the Kelvin-Helmholtz instability theory.
QUANTITATIVE ANALYSIS OF ROD LIKE MICELLE SOLUTIONS VISCOSITY USING MICROSCOPIC PARAMETERS
Authors: GUO HONGKAI , TAO RUIBAO , LIN MINYUE
Published: March 2003

We modify the Hayter-Penfold formalism and gave a quantitative analysis to fit the viscosity of rod-like micelles solutions under shear using measured small-angle neutron scattering (SANS) intensity. The original formalism is applicable to a dilute solution, but we found that the theory can fit our measured results excellently if we use the effective viscosity of the solution in place of the solvent viscosity of the original formalism. The fittings yielded good values just the same as our experiment results.
LATTICE-BGK SIMULATION OF STRATIFIED FLOW OVER A BACKWARD-FACING STEP
Authors: GUO WEIBIN , SHI BAOCHANG , WANG NENGCHAO , GUO ZHAOLI
Published: March 2003

A numerical simulation for steady stably-stratified flow over a two-dimensional backward-facing step with a Froude number of 16/9, a Reynolds number of 800 and a Prandtl number of 1.0 is performed using a newly developed thermal lattice-BGK model. Excellent agreement between the present results and those of previous studies shows that the lattice-Boltzmann method is an efficient simulation method for complex flow.
DOMAIN-DECOMPOSITION TECHNIQUE IN LATTICE BOLTZMANN METHOD
Authors: GUO ZHAOLI , ZHENG CHUGUANG , SHI BAOCHANG
Published: March 2003

In this paper a domain-decomposition technique is proposed in the framework of the lattice Boltzmann method in order to handle flows in irregular geometries. The 2D flow in a channel with a square or slant branch cavity is simulated based on this technique.
LATTICE-BOLTZMANN SIMULATIONS OF FLOW THROUGH NAFION POLYMER MEMBRANES
Authors: HAYASHI HIDEMITSU , YAMAMOTO SATORU , HYODO SHI-AKI
Published: March 2003

Simulations of flow through three-dimensional porous structures of NAFION polymer membranes are performed with a Lattice-Boltzmann method (LBM) for incompressible fluid. Geometry data of NAFION are constructed from a result of a dissipative particle dynamics simulation for three values of the water content, 10%, 20%, and 30%, and are used as the geometry input for the LBM. Permeability of the porous structure is extracted from results of the LBM simulation using Darcy's low. The permeability K is shown to be expressed as K = L2 × Ktpl with a characteristic length L and the dimensionless permeability Ktpl depending only on the topological structure of the porous media. Dependence of Ktpl is examined on the pressure gradient, the fluid viscosity, and the resolution of the computational grid.
THE JEFFERY-HAMEL PROBLEM: A NUMERICAL LATTICE-BOLTZMANN STUDY
Authors: HÁZI GÁBOR , FARKAS ISTVÁN
Published: March 2003

In this paper, we present a numerical study of the Jeffery-Hammel problem using the lattice-Boltzmann method. We study three situations: pure inflow, pure outflow, and outflow with backflow. We demonstrate that the lattice-Boltzmann method gives not only qualitatively but also quantitatively accurate solutions for this problem. From the point of view of stability of the flow, the recent results of bifurcation theory are also briefly considered from the viewpoint of our numerical results.
A LATTICE BOLTZMANN FOR DISORDERED FLUIDS
Authors: LAMURA ANTONIO , SUCCI SAURO
Published: March 2003

A variant of the lattice Boltzmann scheme is presented as a mesoscopic model of glassy behavior. A hierarchical density-dependent interaction potential is introduced, which allows the coexistence and competition of multiple density minima. We find that this competition allows to model geometrical frustration which produces disordered patterns with sharp density contrasts and no phase-separation. A way of modeling mechanical arrest of real glasses is also proposed and discussed.
LATTICE BOLTZMANN SIMULATION OF DEFORMABLE MEMBRANE IN FLUID
Authors: LI HUABING , FANG HAIPING , LIN ZHIFANG
Published: March 2003

A lattice Boltzmann method is proposed to simulate the two-dimensional membrane. Numerical simulation shows that at a critical value of membrane tension, the pattern of the membrane at transient state behaves like a standing wave with a node staying at rest. In addition, when the membrane is relatively soft or stiff, it will evolve into a steady-state close to its initial straight pattern.
A LATTICE BOLTZMANN MODEL FOR A SOLID BODY
Authors: MARCONI STEFAN , CHOPARD BASTIEN
Published: March 2003

The lattice Boltzmann wave equation is adapted to model the motion of displacements within a 2d solid. Momentum, energy are shown to obey conservation laws. Borders and contact conditions are easily dealt with. Three experiments serve as illustrations: crack propagation, fragmentation and a dynamic contact problem.
SIMULATION OF THERMAL FLOWS BY TAYLOR SERIES EXPANSION- AND LEAST SQUARE-BASED LATTICE BOLTZMANN METHOD COUPLING WITH MACROSCOPIC THERMAL EQUATION
Authors: NIU X. D. , SHU C. , CHEW Y. T.
Published: March 2003

In this paper we use the Taylor series expansion- and least square-based lattice Boltzmann method to solve thermal flows. By introducing the "thermal source" into the isothermal lattice Boltzmann equation, and coupling with an explicit evaluation of temperature from the macroscopic thermal equation, the macroscopic property of the thermal flows can be obtained. To show the effectiveness of the method presented, the nature convection in the annulus between concentric horizontal circular and square cylinders was simulated and good results were obtained.
SIMULATION OF NATURAL CONVECTION BY TAYLOR SERIES EXPANSION- AND LEAST SQUARE-BASED LBM
Authors: PENG YAN , SHU C. , CHEW Y. T.
Published: March 2003

The Taylor series expansion- and least squares- based lattice Boltzmann method (TLLBM) is used in this paper to extend the internal energy density distribution function (IEDDF) thermal model to be used on the arbitrary geometry in order to solve practical thermo-hydrodynamics in incompressible limit. The TLLBM essentially has no limitation on the mesh structure and the lattice model. Its use in the thermal model was validated by the numerical simulation of natural convection in a square cavity. Then its application on the curved boundary, natural convection in concentric annuli, was carried out. Favorable results were obtained and compared well with the benchmark data.
LATTICE BOLTZMANN METHOD FOR TWO-PHASE FLOWS
Authors: SETA TAKESHI , KONO KOJI , CHEN SHIYI
Published: March 2003

A lattice Boltzmann method (LBM) for two-phase nonideal fluid flows is proposed based on a particle velocity-dependent forcing scheme. The resulting macroscopic dynamics via the Chapman-Enskog expansion recover the full set of thermohydrodynamic equations for nonideal fluids. Numerical verification of fundamental properties of thermal fluids, including thermal conductivity and surface tension, agrees well with theoretical predictions. Direct numerical simulations of two-phase phenomena, including phase-transition, bubble deformation and droplet falling and bubble rising under gravity are carried out, demonstrating the applicability of the model.
THERMAL LATTICE BGK SIMULATION OF TURBULENT NATURAL CONVECTION DUE TO INTERNAL HEAT GENERATION
Authors: SHI BAOCHANG , GUO ZHAOLI
Published: March 2003

A thermal lattice BGK model with a robust boundary scheme for the Boussinesq incompressible fluids is introduced. The 2D numerical simulation of natural convection flow due to internal heat generation in a square cavity are performed at Rayleigh numbers 106 - 1012 and Prandtl numbers 0.25 and 0.6. The numerical results are compared with those of previous studies in detail.
LATTICE BOLTZMANN SIMULATION OF INTERFACIAL DEFORMATION
Authors: TAKADA NAOKI , TOMIYAMA AKIO , HOSOKAWA SHIGEO
Published: March 2003

This study describes the numerical simulations of two-phase interfacial deformations using the binary fluid (BF) model in the lattice Boltzmann method (LBM), where a macroscopic fluid involves mesoscopic particles repeating collisions and propagations and an interface is reproduced in a self-organizing way by repulsive interaction between different kinds of particles. Schemes for the BF model are proposed to simulate motions of immiscible two phases with different mass densities. For higher Reynolds number, the finite difference-based lattice Boltzmann scheme is applied to the kinetic equations of particles, which include convection terms to reduce the diffusivity of each phase volume. In addition, two parameters are introduced into the BF model to adjust surface tension and interfacial thickness independently. The numerical results of three-dimensional bubble motion under gravity and two-dimensional droplet deformation under shear stress indicate that the lattice-Boltzmann BF model with the proposed schemes would be applicable to simulating interfacial dynamics of immiscible two-phase fluids.
NUMERICAL SIMULATION OF THE VAPOR FILM COLLAPSE BEHAVIOR AT VAPOR EXPLOSION WITH THREE-DIMENSIONAL LATTICE GAS THERMAL-HYDRAULIC AUTOMATA METHOD
Authors: TOCHIO DAISUKE , ABE YUTAKA , MATSUKUMA YOSUKE , NARIAI HIDEKI
Published: March 2003

In order to clarify the dominant driving force of complex vapor film collapse behavior, numerical simulation is performed with three-dimensional fifteen-velocity lattice gas automata method. As the result, numerical result is qualitatively different from the experimental result.

On the other hand, numerical simulation of vapor film collapse behavior is performed with three-dimensional fifteen-velocity lattice gas automata method including phase-change effect. As the result, numerical result is qualitatively similar to the experimental results. Comparison between the experimental result and the numerical result confirms that experimentally observed vapor film collapse behavior is dominated not by fluid motion but by phase change.
LB SIMULATION ON COMBUSTION WITH TURBULENCE
Authors: YAMAMOTO KAZUHIRO
Published: March 2003

In this study, we simulate combustion field by the lattice Boltzmann method. We use a compressible model to describe the behavior of a turbulent non-premixed flame in the mixing layer of two co-flowing streams, one of propane and the other of air. By the assumption of fast-chemistry and unity Lewis number, we adopt the conserved scalar approach to reduce computational costs. In this case, the instantaneous chemical composition of the mixture at a given spatial location is at chemical equilibrium. This is so-called laminar flamelet model where the temperature and concentration are obtained by mixture fraction, which is determined by the degree of mixing of fuel and oxidizer. Results show that a thin flame zone separates two fluids of fuel and oxidizer, and the interaction between flame and a vortex pair is observed.
SIMULATION OF HIGHLY LOADED GAS–SOLID TWO-PHASE FLOWS BY COMBINING A CELLULAR AUTOMATA FOR THE PARTICLES WITH A LATTICE BOLTZMANN FLOW SOLVER
Authors: ZEISER T. , TREIBIG J. , BRENNER G. , DURST F.
Published: March 2003

Chemical reactors with highly loaded gas–solid flows — such as one might find in fluidized beds and riser-downer systems — play an increasingly important role in chemical engineering. Experimental measurements and numerical simulations with standard techniques are rather limited due to the high volume fraction of the particulate solid phase. Therefore, in this paper a completely different simulation approach based on a cellular automata–like description of a simple particle–fluid micro–world is presented which can provide a new entry point for more reliable simulations.
HYDRODYNAMIC CHARACTERISTICS OF ER FLUID FLOWS IN JOURNAL BEARINGS
Authors: ZHU KE-QIN , PENG JIE
Published: March 2003

A numerical analysis is performed on the hydrodynamic characteristics of electrorheological(ER) fluid flows in journal bearings based on the basic hydrodynamic equations. The flow field is assumed to be incompressible and isotropic, the Bingham plastic model is used to describe the behavior of ER fluids. The effect of bearing eccentricity ratio and applied electric field intensity has been studied attentively. It shows that control of the journal bearing through external electric field is much more feasible in high eccentricity ratio bearing than in low eccentricity ratio one.
STRUCTURE EVOLUTION OF AN ER FLUID UNDER ELECTRIC AND SHEAR FIELDS
Authors: CAO J. G. , LU L. , ZHOU L. W.
Published: March 2003

With the combined application of an electric field and shear field, the particles in an ER fluids form cluster structure in the direction of shear. The morphology of the cluster structure was described, and it is found in the experiments that the mean cluster size, S mean, is proportional to [Formula: see text] and E0.64.
PHASE SEPARATION OF FERROFLUIDS IN APPLIED FIELD
Authors: GUO HONGKAI , TAO RUIBAO , SHI AN-CHANG
Published: March 2003

We have analyzed the ground state of a ferrofluid by minimizing the dipolar-dipolar interaction energy of the system. The uniform, or random like phase is not stable and will be decomposed into a stripe phase when an external field is applied. The energy as a function of the optimum thickness of columns in stripe phase and in thickness of the cell as well as the volume fraction is studied.
VISCOELASTICITY OF COMPRESSED GRANULAR ASSEMBLY
Authors: HU L. , CHEN Z. M. , QIAN C. L. , ZHOU L. W.
Published: March 2003

The dynamic viscoelasticity of nickel and quartz granular assembly compressed under high pressures between 5-17 MPa was studied experimentally. The experiment demonstrates that the elastic property always dominates in the current experimental environment. The experiment also shows that the storage modulus G' of the compressed assembly consist of spherical nickel beads changes with compressing pressure p faster than G ' ~ p0.43, which supports the quasielastic model.
ELECTROROTATION OF COLLOIDAL SUSPENSIONS
Authors: HUANG J. P. , YU K. W. , GU G. Q.
Published: March 2003

We investigate the pressure effect on the eletrorotation (ER) spectrum of living cell suspensions by considering the particle shape effect. Based upon the spectral representation theory, we consider coated oblate spheroidal particles and present a theoretical study of ER spectrum. Analytic expressions for the characteristic frequency as well as the dispersion strength can be obtained, thus simplifying the fitting of experimental data. From the theoretical analysis, we find that the cell shape, coating as well as material parameters can change the ER spectrum. We demonstrate good agreement between our theoretical predictions and experimental data on human erythrocytes suspensions.
CRYSTAL GROWTH KINETICS AND FLUID FLOW
Authors: MILLER W.
Published: March 2003

A new type of a lattice phase-field model is developed and coupled with the lattice Boltzmann method to compute the soldification influenced by convection. Two methods of treating the solid-fluid interaction within the lattice Boltzmann scheme are tested.
DEVELOPMENTS TOWARD SIMULATION OF ENTANGLED POLYMER MELTS BY DISSIPATIVE PARTICLE DYNAMICS (DPD)
Authors: PAN GUOAI , MANKE CHARLES W.
Published: March 2003

A segmental repulsion force is developed to reduce the frequency of artificial chain segment crossing events in DPD simulations of the dynamics of polymer melts. The scaling of viscosity and center of mass diffusion coefficients with chain length show transitions in scaling exponents at a critical entanglement chain length. Above the entanglement chain length, the scaling exponent for the diffusion coefficient is close to the experimental value of -2, but the scaling exponent for viscosity is close to +2, which is smaller than the experimental value of +3.4. Without segmental repulsion forces, chain segment crossings occur freely, and the scaling of both diffusion coefficient and viscosity follow the Rouse model for all chain lengths.
TRANSIENT YIELD CHARACTERISTICS OF ER FLUIDS BETWEEN ROTARY CONCENTRIC CYLINDERS
Authors: PENG JIE , ZHU KE-QIN , XI BAO-SHU
Published: March 2003

The transient yield characteristics of electrorheological(ER) fluids between rotary concentric cylinders have been studied. The ER fluids are treated as a homogeneous continuum obeying the Bingham plastic constitutive equation. A numerical algorithm is developed in which the yield surface is treated as a moving boundary. It can be found that the yield characteristics of ER fluids depend strongly on parameter β of the yield stress equation. The demarcation point of β is 2.0 and for β > 2.0 the transient yield characteristics are entirely different from those for β < 2.0. From this research it can also be found that there is a retardation time from the exertion of an electric field to the appearance of the unyielded region, and the retardation time becomes shorter while the electric fields becomes stronger.
MONTE CARLO SIMULATION OF SELF-ASSEMBLED AMPHIPHILIC DIBLOCK COPOLYMER IN SOLUTION
Authors: SUN PINGCHUAN , YIN YUHUA , LI BAOHUI , JIN QINGHUA , DING DATONG
Published: March 2003

In this paper, Monte Carlo method is applied to simulate the process of the self-assembly of amphiphilic diblock copolymer with a series of block lengths of the insoluble and soluble blocks. Under the given simulation conditions, the diblock copolymers form spherical micelles in solution. The dependence of the core radii of spherical micelles on both block lengths is obtained and compared with experimental results of Eisenberg and coworkers.
SHEAR WAVE IN GLUTIN AS A SOFT MATTER
Authors: ZHANG W. H. , ZHANG J. X.
Published: March 2003

This paper focuses on the function between the internal friction and frequency in soft matters. It attempts to prove that the shear wave can interact with microstructure units of certain sizes in soft matters. The specimen used in our experiment is glutin. Using the apparatus1 developed by ourselves, we get the frequency spectrum of glutin, and point out that the spectrum is an inherent physical property of the substance.
THE ORIGIN OF SPURIOUS VELOCITIES IN LATTICE BOLTZMANN
Authors: WAGNER ALEXANDER J.
Published: March 2003

Stationary droplets simulated by multi-phase lattice Boltzmann methods lead to spurious velocities around them. In this article I report the origin of these spurious velocities for one example and show how they can be avoided.
COMPUTER SIMULATIONS OF ER FLUIDS IN DID MODEL
Authors: YU K. W.
Published: March 2003

Theoretical investigations on electrorheological (ER) fluids are usually concentrated on monodisperse systems. Real ER fluids must be polydisperse in nature, i.e., the suspended particles can have various sizes and/or different dielectric constants. An initial approach for these studies would be the point-dipole (PD) approximation, which is known to err considerably when the particles approach and finally touch due to multipolar interactions. A dipole-induced-dipole (DID) model is shown to be both more accurate than the PD model and easy to use. The DID model is applied to simulate the athermal aggregation of particles in ER fluids and the aggregation time is found to deviate significantly as compared to the PD model. Moreover, the inclusion of DID force further complicates the results because the symmetry between positive and negative contrasts will be broken by the presence of dipole-induced interactions.
VERIFICATION OF MULTI-COMPONENT LATTICE-BOLTZMANN METHOD
Authors: NIIMURA HIROAKI
Published: March 2003

We verified the multi-component multi-phase Lattice-Boltzmann method which had been proposed by X. Shan and H. Chen (1993) in points of wetting phenomena of interface between three fluid phases, interfacial tension influenced by components on the interface and phase segregation phenomena due to wetting. As the results, the wetting and the phase segregation phenomena are agreeably reproduced and controlled. We also show an example of deformation patterns of multi-phase system under shear stress.
SIMULATION OF FLUID FLOW AND HEAT TRANSFER IN A PLANE CHANNEL USING THE LATTICE BOLTZMANN METHOD
Authors: TANG G. H. , TAO W. Q. , HE Y. L.
Published: March 2003

Forced convective flow and heat transfer between two parallel plates are studied using the lattice Boltzmann method (LBM) in this paper. Three kinds of thermal boundary conditions at the top and bottom plates are studied. The velocity field is simulated using density distribution function while a separate internal energy distribution function is introduced to simulate the temperature field. The results agree well with data from traditional finite volume method (FVM) and analytical solutions. The present work indicates that LBM may be developed as a promising method for predicting convective heat transfer because of its many inherent advantages.
Two Loci Affect Angiotensin I–Converting Enzyme Activity in Baboons
Authors: Kammerer Candace M. , Rainwater David L. , Schneider Jennifer L. , Cox Laura A. , Mahaney Michael C. , Rogers Jeffrey , VandeBerg Jane F.
Published: March 2003

Serum LDL cholesterol (LDLC) concentrations and ACE activities are risk factors for the development of cardiovascular disease (CVD). However, the relationship between ACE and CVD susceptibility, and possible mechanisms of action, is controversial. With data on 622 pedigreed baboons, we used statistical genetic methods to determine the mode of inheritance of ACE activities and its relationship to LDLC on different diets. ACE activity was moderately heritable, and quantitative trait linkage analyses detected a quantitative trait locus (QTL) for ACE activity on the baboon homolog of human chromosome 17 (near the ACE structural locus, maximum multipoint lod=7.5, genomic
P
=0.000003). Bivariate analyses revealed that ACE activity was genetically correlated (ρ
G
) with LDLC response (LDLC
RC
) to a high-cholesterol diet (ρ
G
=0.30±0.13,
P
=0.01) but not to LDLC on a basal diet (ρ
G
=0.08±0.13). Bivariate genetic analyses indicated that a previously detected QTL for LDLC
RC
had significant (
P
=0.025) pleiotropic effects on ACE activity levels and accounted for the genetic correlation. Therefore, we have detected 2 putative loci that affect ACE activity in baboons, one of which also affects LDLC dietary response. The existence of at least 2 genes that affect ACE activity, one of which is diet-responsive, may help explain the lack of consistency among studies of the relationship between ACE and CVD.
Characterization of an Animal Model of Postmenopausal Hypertension in Spontaneously Hypertensive Rats
Authors: Fortepiani Lourdes A. , Zhang Huimin , Racusen Lorraine , Roberts L. Jackson , Reckelhoff Jane F.
Published: March 2003

Blood pressure (BP) increases in postmenopausal women. The mechanisms responsible are unknown. The present study was performed to characterize a model of postmenopausal hypertension in the rat and to determine the role that oxidative stress may play in mediating the postmenopausal hypertension. Spontaneously hypertensive rats were ovariectomized (ovx) or left intact (PMR) at 8 months and were aged to 18 months. These animals were compared with young females (YF; 4 or 8 months of age) and old males (18 months) for some measurements. Estradiol levels were decreased in PMR rats to levels not different from YF rats in proestrous or from old males. BP increased progressively with age in PMR rats but not in ovx or male rats, such that the gender difference in hypertension disappeared by 18 months. Glomerular filtration rate was lower in ovx and PMR rats than in YF rats. Renal plasma flow and renal vascular resistance were similar between YF and ovx rats, but lower and higher, respectively, in PMR rats. Serum testosterone increased by 60% in ovx rats and 400% in PMR rats compared with YF rats. Plasma renin activity also increased in PMR rats but not in ovx rats. Chronic treatment (for 8 months beginning at 8 months of age) of PMR rats with vitamins E and C, but not tempol, resulted in a significant reduction in BP and excretion of F
2
-isoprostanes. In contrast, tempol, but not vitamins E and C, reduced BP in old males. These data suggest that the PMR rats, but not ovx rats, may be a suitable model for the study of postmenopausal hypertension, and that oxidative stress plays a role in the increased BP.
Microarray Analysis of Rat Chromosome 2 Congenic Strains
Authors: McBride Martin W. , Carr Fiona J. , Graham Delyth , Anderson Niall H. , Clark James S. , Lee Wai K. , Charchar Fadi J. , Brosnan M. Julia , Dominiczak Anna F.
Published: March 2003

Human essential hypertension is a complex polygenic trait with underlying genetic components that remain unknown. The stroke-prone spontaneously hypertensive rat (SHRSP) is a model of human essential hypertension, and a number of reproducible blood pressure regulation quantitative trait loci have been found to map to rat chromosome 2. The SP.WKYGla2c* congenic strain was produced by introgressing a region of rat chromosome 2 from the normotensive Wistar Kyoto (WKY) strain into the genetic background of the SHRSP. Systolic and diastolic blood pressures were significantly reduced in the SP.WKYGla2c* compared with the SHRSP parental strain (198/134±6.1/3.3 versus 172/120±3.8/3.4 mm Hg; F=15.8/8.1,
P
=0.0009/0.013). Genome-wide microarray expression profiling was undertaken to identify differentially expressed genes among the parental SHRSP, WKY, and congenic strain. We identified a significant reduction in expression of glutathione
S
-transferase μ-type 2, a gene involved in the defense against oxidative stress. Quantitative reverse transcription–polymerase chain reaction relative to a β-actin standard confirmed the microarray results with SHRSP mRNA at 8.56×10
−4
±1.6×10
−4
compared with SP.WKYGla2c* 3.67×10
−3
±2.8×10
−4
(95% CI −3.9×10
−3
to −1.8×10
−3
;
P
=0.0034) and WKY 4.03×10
−3
±5.1×10
−4
; (95% CI −5.4×10
−3
to −8.9×10
−4
;
P
=0.027). We also identified regions of conserved synteny, each containing the
Gstm2
gene, on mouse chromosome 3 and human chromosome 1.
Antisense to Epidermal Growth Factor Receptor Prevents the Development of Left Ventricular Hypertrophy
Authors: Kagiyama Shuntaro , Qian Keping , Kagiyama Tomoko , Phillips M. Ian
Published: March 2003

We previously demonstrated that left ventricular hypertrophy (LVH) induced by angiotensin II infusion requires epidermal growth factor receptor (EGFR) activation to mediate the mitogen-activated protein kinase/extracellular signal–regulated kinase (MAPK/ERK) pathway. To test whether the EGFR-mediated MAPK/ERK activation plays an important role in development and maintenance of LVH in spontaneously hypertensive rats (SHR), we investigated the effects of antisense oligodeoxynucleotide to EGFR (EGFR-AS) on LVH and blood pressure in young and adult SHR. EGFR-AS, sense oligonucleotide to EGFR (EGFR-S; 1.5 mg/kg), or vehicle control (5% dextrose) with liposome was injected once a week for 2 months in 5- or 13-week-old SHR. The effect of EGFR-AS on the expression of EGFR and phosphorylated ERK in the heart were examined by Western blots. After treatment, EGFR-AS significantly (
P
<0.05) decreased left ventricular weight/body weight and blood pressure in young SHR compared with EGFR-S or control-treated rats. In adult SHR, EGFR-AS did not affect left ventricular weight/body weight and blood pressure. EGFR and phosphorylated ERK significantly declined from 5 to 20 weeks (
P
<0.05). EGFR-AS, but not EGFR-S, significantly (
P
<0.05) decreased the expression of EGFR and phosphorylated ERK in young SHR, but had no significant effect in adult SHR. These results suggests that EGFR-mediated ERK activation is critically important for LVH in young SHR. This may be related to the high levels of EGFR and phosphorylated ERK in young SHR, suggesting a critical role of the EGFR-activated ERK pathway in cardiovascular development but not in the maintenance of established LVH in adult SHR.
Endothelin Inhibits NPR-A and Stimulates eNOS Gene Expression in Rat IMCD Cells
Authors: Ye Qiong , Chen Songcang , Gardner David G.
Published: March 2003

We have shown in previous studies that high extracellular tonicity is associated with increased expression of the type A natriuretic peptide receptor (NPR-A) and reduced expression of the endothelial NO synthase (eNOS) gene in cultured rat inner-medullary collecting duct cells. The vasoactive peptide endothelin has been shown to be avidly expressed in this nephron segment, and to be subject to osmotic regulation. We asked whether endothelin might play a role in the control of basal or osmotically regulated NPR-A or eNOS gene expression in these cells. Although exogenous endothelin had little or no effect on basal expression of eNOS mRNA or protein or NPR-A gene expression, both the type A (BQ610) and type B (IRL1038) endothelin receptor antagonists proved capable of reducing eNOS mRNA and protein expression, and increasing levels of the NPR-A mRNA. Increased extracellular tonicity reduced endothelin mRNA accumulation in these cells (≈15% of control levels); however, exogenous endothelin failed to normalize osmotically increased NPR-A activity or expression, or osmotically suppressed eNOS expression. Collectively, these data demonstrate the presence of a number of independent but highly interactive local regulatory networks governing fluid and electrolyte handling in this distal nephron segment.
Neural Control of the Kidney
Authors: DiBona Gerald F.
Published: March 2003

This article provides a chronological perspective on the development of knowledge concerning the neural control of renal function and is divided into three parts: the past, the present, and the future.
20-HETE–Induced Contraction of Small Coronary Arteries Depends on the Activation of Rho-Kinase
Authors: Randriamboavonjy Voahanginirina , Busse Rudi , Fleming Ingrid
Published: March 2003

20-HETE is a potent constrictor of small blood vessels and has been suggested to play a crucial role in the generation of myogenic tone and the development of hypertension. In the present study, we investigated the mechanisms by which exogenously applied 20-HETE modulates vascular tone in small porcine coronary arteries. In organ chamber experiments, 20-HETE elicited a concentration-dependent contraction of small porcine coronary artery rings that was partially inhibited by the cyclooxygenase inhibitor diclofenac, the thromboxane and endoperoxide receptor antagonist SQ29548, and the thromboxane A
2
synthase inhibitor furegrelate. Removal of endothelium attenuated the response to 20-HETE, whereas preconstriction of endothelium-denuded vessels to 25% of the maximum response with KCl markedly enhanced the response to 20-HETE. This 20-HETE–induced contraction was not associated with a significant increase in the intracellular concentration of Ca
2+
. 20-HETE–induced contraction was also observed in β-escin–permeabilized arteries precontracted with a submaximal concentration of Ca
2+
and was abolished by the Rho-kinase inhibitor Y27632, but was insensitive to the PKC inhibitor RO 31-8220. 20-HETE elicited the phosphorylation of the myosin light chain (MLC20) in coronary artery rings, an effect that was sensitive to Y27632 and mimicked by the thromboxane analog U46619. These data suggest that in small porcine coronary arteries, 20-HETE can induce contraction by 2 mechanisms, one endothelium-dependent involving the cyclooxygenase-dependent generation of vasoconstrictor prostanoids, and the other endothelium-independent. The latter response is associated with the activation of Rho-kinase, phosphorylation of MLC20, and sensitization of the contractile apparatus to Ca
2+
.
High-Salt Diet Increases Sensitivity to NO and eNOS Expression But Not NO Production in THALs
Authors: Ortiz Pablo , Stoos Barbara A. , Hong Nancy J. , Boesch Dianne M. , Plato Craig F. , Garvin Jeffrey L.
Published: March 2003

l
-Arginine inhibits thick ascending limb (THAL) NaCl absorption by activating endothelial NO synthase (eNOS) and increasing NO production. Inhibition of renal NO production combined with a high-salt diet produces hypertension, and the THAL has been implicated in salt-sensitive hypertension. We hypothesized that a high-salt diet enhances the inhibitory action of
l
-arginine on NaCl absorption by THALs because of increased eNOS expression and NO production. To test this, we used isolated THALs from rats on a normal-salt (NS) or high-salt diet (HS) for 7 to 10 days.
l
-Arginine (1 mmol/L) decreased chloride absorption by 56±10% in THALs from rats on a HS diet, but only 29±3% in THALs from rats on a NS diet. eNOS expression in isolated THALs from rats on a HS diet was increased by 3.9-fold compared with NS (
P
<0.03). However,
l
-arginine increased NO levels to the same extent in THALs from both groups, as measured with DAF-2 DA or a NO-sensitive electrode. To determine whether a HS diet increases the sensitivity of the THAL to NO, we tested the effects of the NO donor spermine NONOate on chloride absorption. In THALs from rats on a HS diet, 1 and 5 μmol/L spermine NONOate reduced chloride absorption by 35±5% and 58±6%, respectively. In contrast, these same concentrations of spermine NONOate reduced chloride absorption by 4±4% (
P
<0.03 versus HS diet) and 43±9% in THALs from rats on a NS diet. We conclude that a HS diet enhances the effect of NO in the THAL.
l
-Arginine–stimulated NO production was not enhanced by a HS diet, despite increased eNOS protein.
PKC-ζ Mediates Norepinephrine-Induced Phospholipase D Activation and Cell Proliferation in VSMC
Authors: Parmentier Jean-Hugues , Smelcer Philip , Pavicevic Zoran , Basic Edin , Idrizovic Azra , Estes Anne , Malik Kafait U.
Published: March 2003

Norepinephrine (NE) stimulates phospholipase D (PLD) activity and cell proliferation in vascular smooth muscle cells (VSMCs). The objective of this study was to determine the contribution of PKC-ζ to NE-induced PLD activation and cell proliferation in VSMCs. PLD activity was measured by the formation of [
3
H]phosphatidylethanol in VSMCs labeled with [
3
H]oleic acid and exposed to ethanol. A high basal PLD activity was detected, and NE increased PLD activity over basal by 70%. This increase was abolished by the broad-range PKC inhibitor Ro 31-8220 (1 μmol/L, 30 minutes) and myristoylated PKC-ζ pseudosubstrate peptide inhibitor (25 μmol/L, 1 hour). Transfection of VSMCs with PKC-ζ antisense, but not sense, oligonucleotides, which reduced PKC-ζ protein level and basal PLD activity, caused a 92% decrease in NE-induced PLD activation. NE-induced increase in PLD activity was also reduced by 61% in cells transfected with kinase-deficient FLAG-T410A-PKC-ζ plasmid but not in those transfected with wild-type PKC-ζ. NE increased immunoprecipitable PKC-ζ activity and phosphorylation, reaching a maximum at 2 and 5 minutes, respectively. NE-induced increase in PKC-ζ activity was inhibited by Ro 31-8220 and by the pseudosubstrate inhibitor. Treatment of VSMCs for 48 hours with PKC-ζ antisense, but not sense, oligonucleotides also inhibited basal and NE-stimulated cell proliferation by 54% and 57%, respectively, as measured by [
3
H]thymidine incorporation. The inhibitor of PLD activity
n
-butanol, but not its inactive analog
tert
-butanol, also reduced the basal and blocked NE-induced cell proliferation. These data suggest that PKC-ζ mediates PLD activation and cell proliferation elicited by NE in rabbit VSMCs.
Vasopressin Induces Vascular Superoxide Via Endothelin-1 in Mineralocorticoid Hypertension
Authors: Li Lixin , Galligan James J. , Fink Gregory D. , Chen Alex F.
Published: March 2003

We have recently reported that endothelin-1 (ET-1), which is increased in the arteries of deoxycorticosterone acetate (DOCA)–salt hypertensive rats, stimulates superoxide production. However, the humoral mechanisms responsible for ET-1–induced superoxide formation in low-renin models of hypertension, such as DOCA-salt hypertension, remain undefined. Vasopressin is known to upregulate vascular preproET-1 gene expression in DOCA-salt rats, an effect that is absent in vasopressin-deficient Brattleboro rats treated with DOCA-salt. The present study tested the hypothesis that vasopressin contributes to ET-1–induced vascular superoxide production in DOCA-salt hypertensive rats. Carotid arterial segments of DOCA, sham (uninephrectomized), or normal (untreated) rats were used for the study. In vitro vasopressin treatment of carotid arteries from normal rats for 24 hours, but not 4 hours, increased both ET-1 and superoxide levels. The increase of vasopressin-induced superoxide was reduced by pretreatment of the vessels with ABT627, a selective ET
A
receptor antagonist ABT627. Vasopressin, ET-1, and superoxide levels were significant elevated in carotid arteries of DOCA-salt rats compared with sham controls. The selective V1-vasopressin receptor antagonist (β-Mercapto-β, β-cyclopentamethylenepropiony
1
, O-Me-Tyr
2
, Arg
8
vasopressin, ME-AVP), decreased superoxide both in vasopressin-treated vessels of normal rats and in vessels of DOCA-salt rats, with a concomitant reduction of ET-1 content. These results suggest that vasopressin increases vascular superoxide levels by stimulating ET-1 formation in mineralocorticoid hypertension, and that V1-vasopressin receptors play an important role in this process.
Administration Time–Dependent Influence of Aspirin on Blood Pressure in Pregnant Women
Authors: Hermida Ramón C. , Ayala Diana E. , Iglesias Manuel
Published: March 2003

This study prospectively investigates the potential influence of low-dose aspirin on blood pressure in pregnant women who were at a higher risk of developing preeclampsia than that of the general obstetric population and who received aspirin at different times of the day according to their rest-activity cycle. A double-blind, randomized, controlled trial was conducted in 341 pregnant women (181 primipara) randomly assigned to 1 of 6 possible groups according to treatment (either placebo or aspirin, 100 mg/day, starting at 12 to 16 weeks of gestation) and the time of treatment: on awakening (time 1), 8 hours after awakening (time 2), or before bedtime (time 3). Blood pressure was automatically monitored for 48 consecutive hours every 4 weeks from the day of recruitment until delivery, as well as at puerperium. There was no effect of aspirin on blood pressure at time 1 (compared with placebo). A blood pressure reduction was highly statistically significant when aspirin was given at time 2 and, to a greater extent, at time 3 (mean reductions of 9.7/6.5 mm Hg in 24-hour mean for systolic/diastolic blood pressure at the time of delivery as compared with placebo given at bedtime). Differences in blood pressure among women receiving aspirin at different circadian times disappeared at puerperium (
P
>0.096). Results indicate a highly significant effect of aspirin on blood pressure that is markedly dependent on the time of aspirin administration with respect to the rest-activity cycle. Timed use of aspirin at low dose effectively contributes to blood pressure control in women at high risk for preeclampsia.
Decreased Renal Cytochrome P450 2C Enzymes and Impaired Vasodilation Are Associated With Angiotensin Salt-Sensitive Hypertension
Authors: Zhao Xueying , Pollock David M. , Inscho Edward W. , Zeldin Darryl C. , Imig John D.
Published: March 2003

Excess dietary salt intake differentially modulates the activity of cytochrome (CYP) P450 enzymes in kidney cortex. Exactly how increased angiotensin (Ang) II levels and hypertension change the regulatory effect of high salt on CYP450 enzymes remains unclear. The present study investigated the effects of combined administration of Ang II and a high-salt diet on P450 epoxygenase and hydroxylase protein levels in kidney, as well as afferent arteriolar responses to acetylcholine and sodium nitroprusside. High dietary salt administration for 14 days resulted in increased renal cortical CYP2C11 protein levels, and a significant increase of CYP2C11 and CYP2C23 protein levels in renal microvessels. Administration of Ang II in combination with a high-salt diet prevented the upregulation of renal cortical CYP2C11 protein expression observed with high dietary salt alone, and significantly downregulated expression of CYP2C11, CYP2C23, and CYP2J protein in renal microvessels. A high-salt diet alone decreased CYP4A protein in kidney cortex, and renal cortical CYP4A protein level remained at a low level in Ang II–infused rats treated with a high-salt diet. Increases in blood pressure during Ang II infusion were greater in rats fed a high-salt diet. In addition, afferent arteriolar responsiveness to acetylcholine and sodium nitroprusside was significantly attenuated in Ang II–treated rats versus controls. This decrease was significantly enhanced in Ang II–treated rats given a high-salt diet. These results support the hypothesis that an inability to upregulate CYP2C and maintain CYP2J in the rat kidney and impaired afferent arteriolar vasodilation with chronic Ang II infusion contribute to salt-induced elevation of arterial pressure.
Transduction of a Functional Domain of the AT
1
Receptor in Neurons by HIV-Tat PTD
Authors: Vázquez Jorge , Sun Chengwen , Du Jianqing , Fuentes Lucía , Sumners Colin , Raizada Mohan K.
Published: March 2003

Despite advances in transgenic and gene transfer technologies, in vivo structure–function studies of the angiotensin II type I receptor (AT
1
R) have revealed limited information on the diverse actions of angiotensin II. Our objective in the present study was to determine if protein transduction technology with the use of the HIV-Tat protein transduction domain could fill this gap. Recombinant HIV-Tat protein transduction domain fused to EGFP and to the third intracellular loop of the AT
1
R was expressed. Incubation of hypothalamus and brainstem neurons with this peptide indicated an efficient transport of the protein to most of the cells. This transduction was accompanied by an increase in neuronal firing rate, an effect similar to that observed with angiotensin II stimulation of the neuronal AT
1
R. The characteristics of the chronotropic effects of recombinant third intracellular loop and its synthetic counterpart were similar and comparable to the effects of angiotensin II on these neurons. In addition, in the presence of the protein kinase C inhibitor calphostin C, the peptide failed to increase firing rate. These observations demonstrated that transduction of neurons with the third intracellular loop of the AT
1
R produces chronotropic effects similar to those induced by angiotensin II. The data suggests that protein transduction technology could be useful for in vivo AT
1
R domain transduction.
Angiotensin II Regulation of AT
1
and D
3
Dopamine Receptors in Renal Proximal Tubule Cells of SHR
Authors: Zeng Chunyu , Asico Laureano D. , Wang Xiaoli , Hopfer Ulrich , Eisner Gilbert M. , Felder Robin A. , Jose Pedro A.
Published: March 2003

Dopamine and angiotensin II negatively interact to regulate sodium excretion and blood pressure. D
3
dopamine receptors downregulate angiotensin type 1 (AT
1
) receptors in renal proximal tubule cells from normotensive Wistar-Kyoto rats. We determined whether AT
1
receptors regulate D
3
receptors and whether the regulation is different in cultured renal proximal tubule cells from normotensive and spontaneously hypertensive rats. Angiotensin II (10
−8
M/24 hours) decreased D
3
receptors in both normotensive (control, 36±3; angiotensin II, 24±3 U) and hypertensive (control, 30±3; angiotensin II, 11±3 U; n=9 per group) rats; effects that were blocked by the AT
1
receptor antagonist, losartan (10
−8
M/24 hours). However, the reduction in D
3
expression was greater in hypertensive (60±10%) than in normotensive rats (32±9%). In normotensive rats, angiotensin II (10
−8
M/24hr) also decreased AT
1
receptors. In contrast, in cells from hypertensive rats, angiotensin II increased AT
1
receptors. AT
1
and D
3
receptors co-immunoprecipitated in renal proximal tubule cells from both strains. Angiotensin II decreased D
3
/AT
1
receptor co-immunoprecipitation similarly in both rat strains, but basal D
3
/AT
1
co-immunoprecipitation was 6 times higher in normotensive than in hypertensive rats. Therefore, AT
1
and D
3
receptor interaction is qualitatively and quantitatively different between normotensive and hypertensive rats; angiotensin II decreases AT
1
expression in normotensive but increases it in hypertensive rats. In addition, angiotensin II decreases D
3
expression to a greater extent in hypertensive than in normotensive rats. Aberrant interactions between D
3
and AT
1
receptors may play a role in the pathogenesis of hypertension.
Contributions of 20-HETE to the Antihypertensive Effects of Tempol in Dahl Salt-Sensitive Rats
Authors: Hoagland Kimberly M. , Maier Kristopher G. , Roman Richard J.
Published: March 2003

The present study evaluated whether reactive oxygen species–induced alterations in bioavailability of 20-HETE in the kidney contribute to the antihypertensive and renoprotective actions of antioxidant therapy with Tempol in the Dahl salt-sensitive (DS) rat. Superoxide inhibited the synthesis of 20-HETE by renal cortical microsomes and enhanced breakdown of 20-HETE to a more polar product. Addition of Tempol (1 mmol/L) to the drinking water reduced mean arterial pressure from 187±9 to 160±3 mm Hg in DS rats fed an 8%-NaCl diet for 2 weeks. 20-HETE excretion rose from 117±11 to 430±45 ng/day, and 8-isoprostane excretion fell from 14±1 to 8±1 ng/day. Tempol also increased creatinine clearance and reduced the severity of renal damage in DS rats fed a high-salt diet. Blockade of NO synthase with
N
G
-nitro-
l
-arginine methyl ester (25 mg/kg per day) did not attenuate the antihypertensive or renoprotective actions of Tempol in DS rats. However, chronic blockade of the formation of 20-HETE with
N
-hydroxy-
N
′-(4-butyl-2 methylphenyl) formamidine (HET0016, 10 mg/kg per day) blunted the antihypertensive and renoprotective effects of Tempol. These findings indicate that the antihypertensive and renoprotective effects of reducing oxidative stress with Tempol depends in part on increasing the bioavailability of 20-HETE in the kidney.