bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased Neutralization Sensitivity of Recently Emerged CXCR4-Using Human Immunodeficiency Virus Type 1 Strains Compared to Coexisting CCR5-Using Variants from the Same Patient
Authors: Bunnik Evelien M. , Quakkelaar Esther D. , van Nuenen Ad C. , Boeser-Nunnink Brigitte , Schuitemaker Hanneke
Published: December 2006

CXCR4-using (X4) human immunodeficiency virus type 1 (HIV-1) variants evolve from CCR5-using (R5) variants relatively late in the natural course of infection in 50% of HIV-1 subtype B-infected individuals and subsequently coexist with R5 HIV-1 variants. This relatively late appearance of X4 HIV-1 variants is poorly understood. Here we tested the neutralization sensitivity for soluble CD4 (sCD4) and the broadly neutralizing antibodies IgG1b12, 2F5, 4E10, and 2G12 of multiple coexisting clonal R5 and (R5)X4 (combined term for monotropic X4 and dualtropic R5X4 viruses) HIV-1 variants that were obtained at two time points after the first appearance of X4 variants in five participants of the Amsterdam Cohort Studies on HIV-1 infection and AIDS. Recently emerged (R5)X4 viruses were significantly more sensitive to neutralization by the CD4-binding-site-directed agents sCD4 and IgG1b12 than their coexisting R5 viruses. This difference was less pronounced at the later time point. Early (R5)X4 variants from two out of four patients were also highly sensitive to neutralization by autologous serum (50% inhibition at serum dilutions of >200). Late (R5)X4 viruses from these two patients were neutralized at lower serum dilutions, which suggested escape of X4 variants from humoral immunity. Autologous neutralization of coexisting R5 and (R5)X4 variants was not observed in the other patients. In conclusion, the increased neutralization sensitivity of HIV-1 variants during the transition from CCR5 usage to CXCR4 usage may imply an inhibitory role for humoral immunity in HIV-1 phenotype evolution in some patients, thus potentially contributing to the late emergence of X4 variants.
Lethal Infection of K18-
hACE2
Mice Infected with Severe Acute Respiratory Syndrome Coronavirus
Authors: McCray Paul B. , Pewe Lecia , Wohlford-Lenane Christine , Hickey Melissa , Manzel Lori , Shi Lei , Netland Jason , Jia Hong Peng , Halabi Carmen , Sigmund Curt D. , Meyerholz David K. , Kirby Patricia , Look Dwight C. , Perlman Stanley
Published: December 2006

The
severe acute respiratory syndrome (SARS), caused by a novel coronavirus
(SARS-CoV), resulted in substantial morbidity, mortality, and economic
losses during the 2003 epidemic. While SARS-CoV infection has not
recurred to a significant extent since 2003, it still remains a
potential threat. Understanding of SARS and development of therapeutic
approaches have been hampered by the absence of an animal model that
mimics the human disease and is reproducible. Here we show that
transgenic mice that express the SARS-CoV receptor (human
angiotensin-converting enzyme 2 [hACE2]) in airway and other epithelia
develop a rapidly lethal infection after intranasal inoculation with a
human strain of the virus. Infection begins in airway epithelia, with
subsequent alveolar involvement and extrapulmonary virus spread to the
brain. Infection results in macrophage and lymphocyte infiltration in
the lungs and upregulation of proinflammatory cytokines and chemokines
in both the lung and the brain. This model of lethal infection with
SARS-CoV should be useful for studies of pathogenesis and for the
development of antiviral
therapies.
Expression of Viral MicroRNAs in Epstein-Barr Virus-Associated Gastric Carcinoma
Authors: Kim Do Nyun , Chae Hiun-Suk , Oh Sang Taek , Kang Jin-Hyoung , Park Cho Hyun , Park Won Sang , Takada Kenzo , Lee Jae Myun , Lee Won-Keun , Lee Suk Kyeong
Published: December 2006

Epstein-Barr virus (EBV) is associated with about 6 to 16% of gastric carcinoma cases worldwide. Expression of the EBV microRNAs (miRNAs) was observed in B cells and nasopharyngeal carcinoma cells infected with EBV. However, it is not clear if the EBV miRNAs are expressed in EBV-associated gastric carcinomas (EBVaGCs). We found that BART miRNAs but not BHRF1 miRNAs were expressed in EBV-infected gastric carcinoma cell lines and the tumor tissues from patients as well as the animal model. The expression of viral miRNAs in EBVaGCs suggests that these EBV miRNAs may play important roles in the tumorigenesis of EBVaGCs.
PERFECT STOCHASTIC SUMMATION IN HIGH ORDER FEYNMAN GRAPH EXPANSIONS
Authors: CORCORAN J. N. , SCHNEIDER U. , SCHÜTTLER H.-B.
Published: December 2006

We describe a new application of an existing perfect sampling technique of Corcoran and Tweedie to estimate the self energy of an interacting Fermion model via Monte Carlo summation. Simulations suggest that the algorithm in this context converges extremely rapidly and results compare favorably to true values obtained by brute force computations for low dimensional toy problems. A variant of the perfect sampling scheme which improves the accuracy of the Monte Carlo sum for small samples is also given.
EVALUATION OF SKIN AGEING THROUGH WRINKLE ANALYSIS IN CAPACITIVE IMAGES
Authors: BEVILACQUA ALESSANDRO , GHERARDI ALESSANDRO , GUERRIERI ROBERTO
Published: December 2006

Quantitative evaluation of the changes in skin topographic structures are of great importance in the dermocosmetic field to assess subjects response to medical or cosmetic treatments. Although many devices and methods are known to measure these changes, they are not suitable for a routine approach and most of them are invasive. Moreover, it has always been difficult to give a measure of the skin health status as well as of the human aging process by simply analyzing the skin surface appearance. This work describes how a portable capacitive device could be utilized to achieve measurements of skin ageing in vivo and routinely. The capacitive images give a high resolution representation of the skin micro-relief, both in terms of skin surface tissue and wrinkles. In a previous work we dealt with the former; here we have addressed the latter. The algorithm we have developed allowed us to extract two original features from wrinkles: the first is based on photometric properties while the second has been achieved through the multiresolution analysis of the wavelet transform. Accurate experiments accomplished on 87 subjects show how the features we conceived are related to skin ageing.
TENSILE FAILURE OF SINGLE-CRYSTAL AND NANOCRYSTALLINE LENNARD-JONES SOLIDS UNDER UNIAXIAL STRAIN
Authors: LUO SHENG-NIAN , ZHENG LIANQING , AN QI , ZHAO SHIJIN
Published: December 2006

We investigate using molecular dynamics, the tensile failure of single-crystal and nanocrystalline Lennard-Jones solids under uniaxial strain. Stresses are relaxed by plasticity and tensile failure, which are induced via stacking faults, twin planes, void nucleation and growth, and their interactions. Stacking faults and twin planes as well as multiple nanovoids are nucleated at grain boundaries in a nanocrystalline solid. Void formation is characterized by under-coordinated atoms with coordination number ≤ 7, and the critical void size is comparable to a vacancy. For a single crystal, the number of stacking faults and twin planes decreases during failure mostly due to the absorption by nanovoids. In contrast, it increases with strain monotonically for a nanocrystalline solid, where abundant grain boundaries help the nucleation and deter the propagation and absorption of the stacking faults and twin planes, inducing effective dislocation pile-ups at grain boundaries even in the presence of nanovoids.
NUMERICAL SCHEMES OBTAINED FROM LATTICE BOLTZMANN EQUATIONS FOR ADVECTION DIFFUSION EQUATIONS
Authors: SUGA SHINSUKE
Published: December 2006

Stability and accuracy of the numerical schemes obtained from the lattice Boltzmann equation (LBE) used for numerical solutions of two-dimensional advection-diffusion equations are presented. Three kinds of velocity models are used to determine the moving velocity of particles on a squre lattice. A system of explicit finite difference equations are derived from the LBE based on the Bhatnagar, Gross and Krook (BGK) model for individual velocity model. In order to approximate the advecting velocity field, a linear equilibrium distribution function is used for each of the moving directions. The stability regions of the schemes in the special case of the relaxation parameter ω in the LBE being set to ω=1 are found by analytically solving the eigenvalue problems of the amplification matrices corresponding to each scheme. As for the cases of general relaxation parameters, the eigenvalue problems are solved numerically. A benchmark problem is solved in order to investigate the relationship between the accuracy of the numerical schemes and the order of the Peclet number. The numerical experiments result in indicating that for the scheme based on a 9-velocity model we can find the parameters depending on the order of the given Peclet number, which generate accurate solutions in the stability region.
LAMINATED WAVE TURBULENCE: GENERIC ALGORITHMS I
Authors: KARTASHOVA ELENA , KARTASHOV ALEXEY
Published: December 2006

The model of laminated wave turbulence presented recently unites both types of turbulent wave systems — statistical wave turbulence (introduced by Kolmogorov and brought to the present form by numerous works of Zakharov and his scientific school since nineteen sixties) and discrete wave turbulence (developed in the works of Kartashova in nineteen nineties). The main new feature described by this model is the following: discrete effects do appear not only in the long-wave part of the spectral domain (corresponding to small wave numbers) but all through the spectra thus putting forth a novel problem — construction of fast algorithms for computations in integers of order 1012 and more. In this paper we present a generic algorithm for polynomial dispersion functions and illustrate it by application to gravitational water waves and oceanic planetary waves.
COMPETITION AND PREDATION IN A THREE SPECIES MODEL
Authors: SZWABIǸSKI JANUSZ , PȨKALSKI ANDRZEJ , TROJAN KAMIL
Published: December 2006

A model of dynamics of three interacting species is presented. Two of the species are prey and one is predator, which feeds on both prey, however with some preference to one type. Prey compete for space (breeding) although they always have access to food. Predators in order to survive and reproduce must catch prey, otherwise they die of hunger. The dynamics of the model is found via differential equations in the mean-field like approach and through computer simulations for agent-based method. We show that the coexistence of the three species is possible in the mean-field model, provided the preference of the predators is small, whereas from simulation it follows that the stochastic fluctuations drive, generally, one of the prey populations into extinction. We have found a different type of behavior for small and large systems and a rather unexpected dependence of the coexistence chance of the preference parameter in bigger lattices.
CHARGE AND STATISTICS OF QUASIPARTICLES IN FRACTIONAL QUANTUM HALL EFFECT
Authors: BASU B. , BANDYOPADHYAY P. , DHAR S.
Published: December 2006

We have studied here the charge and statistics of quasiparticle excitations in FQH states on the basis of the Berry phase approach incorporating the fact that even number of flux quanta can be gauged away when the Berry phase is removed to the dynamical phase. It is observed that the charge q and statistical parameter θ of a quasiparticle at filling factor ν = n/(2pn+1) are given by q = (n/2pn+1)e and θ = n/(2pn+1), with the fact that the charge of the quasihole is opposite to that of the quasielectron. Using Laughlin wave function for quasiparticles, numerical studies have been done following the work of Kjønsberg and Myrheim1 for FQH states at ν = 1/3 and it is pointed out that as in case of quasiholes, the statistics parameter can be well defined for quasielectrons having the value θ = 1/3.
QUANTIZED HYDRODYNAMIC THEORY OF BOSONS IN QUASI-ONE-DIMENSIONAL HARMONIC TRAP
Authors: GHOSH TARUN KANTI
Published: December 2006

We analytically study effects of density and phase fluctuations of quasi-one-dimensional degenerate atomic Bose gases in the mean-field as well as in the hard-core bosons regimes. We obtain the analytic expressions for dynamic structure factors in both the regimes. We also calculate single-particle density matrix and momentum distribution by taking care of the phase fluctuations upto fourth-order term, the density fluctuations as well as the non-condensate density in both the regimes. In the mean-field regime, there is a long-tail in the momentum distributions at large temperature, which can be used to identify the quasi-condensate from a pure condensate. The single-particle correlation functions of hard-core bosons is almost zero even at zero temperature due to the fermionization of the bosonic systems. Two-particle correlation function in the hard-core bosons regime shows many deep valleys at various relative separations. These valleys at various relative separations imply shell structure due to the Pauli blocking in real space.
ENERGY LEVEL OF ELECTRON IN AN ANISOTROPIC QUANTUM DOT UNDER A MAGNETIC FIELD BY AN INVARIANT EIGENOPERATOR METHOD
Authors: FAN HONG-YI , WANG TONG-TONG , YANG YAN-LI
Published: December 2006

We show that the recently proposed invariant eigenoperator method can be successfully applied to solving energy levels of electron in an anisotropic quantum dot in the presence of a uniform magnetic field (UMF). The result reduces to the energy level of electron in isotropic harmonic oscillator potential and in UMF naturally. The Landau diamagnetism decreases due to the existence of the anisotropic harmonic potential.
GENETIC PROGRAMMING APPROACH FOR ELECTRON-ALKALI-METAL ATOM COLLISIONS
Authors: EL-BAKRY SALAH YASEEN , RADI AMR
Published: December 2006

New technique is presented for modeling the total cross sections of electron scattering by Na, K, Rb and Cs atoms in the low and intermediate energy regions. The calculations have been performed in the framework of genetic programming (GP) technique. The GP has been running based on the experimental data of the total collisional cross sections to produce the total cross sections for each target atom. The incident energy and atomic number as well as the static dipole polarizability have been used as input variables to find the functions that describe the total collisional cross sections of the scattering of electrons by alkali atoms. The experimental, calculated and predicted total collisional cross sections are compared. The discovered functions show a good match to the experimental data.
LOCALIZED WAVEFUNCTIONS AND MAGNETIC BAND STRUCTURE FOR LATERAL SEMICONDUCTOR SUPERLATTICES
Authors: KLIROS G. S. , DIVARI P. C.
Published: December 2006

In this paper we present calculations on the electronic band structure of a two-dimensional lateral superlattice subject to a perpendicular magnetic field by employing a projection operator technique based on the ray-group of magnetotranslation operators. We construct a new basis of appropriately symmetrized Bloch-like wavefunctions as linear combination of well-localized magnetic Wannier functions. The magnetic field was consistently included in the Wannier functions defined in terms of free-electron eigenfunctions in the presence of external magnetic field in the symmetric gauge. Using the above basis, we calculate the magnetic energy spectrum of electrons in a lateral superlattice with bi-directional weak electrostatic modulation. Both a square lattice and a triangular one are considered as special cases. Our approach based on group theory handles the cases of integer and rational magnetic fluxes in a uniform way and the provided basis could be convenient for further both analytic and numerical calculations.
NONLINEAR ADIABATIC DYNAMICS OF SMALL FERROMAGNETIC PARTICLES
Authors: USATENKO O. V. , CHUBYKALO-FESENKO O. A. , GARCÍA SÁNCHEZ F.
Published: December 2006

The purpose of this work is to present an analytical description of dynamics of small ferromagnetic particles with uniaxial anisotropy and the slowly varying magnetic field applied at an arbitrary angle to the anisotropy axis. Considerable attention is given to the nonlinear aspects of adiabatic dynamics. Theoretical analysis based on the consideration of the Landau–Lifshitz–Gilbert equation employs an asymptotic expansion similar to the famous semi-classical WKBJ solution of quantum mechanics equations. The small parameter of the expansion is the ratio of characteristic frequency of the applied magnetic field to the precession frequency. The nonlinear equation describing the slow dynamics of small ferromagnetic particles is derived. The applicability conditions of the developed theory are presented. The nonlinear corrections to the precessional frequency are derived. It is shown that in numerical simulation using the Landau–Lifshitz–Gilbert equation it is not possible to neglect precessional terms at long simulation times due to the nonlinear dynamic correction to a position of the orbit center.
GEOMETRIC PHASE IN A MESOSCOPIC LC CIRCUIT WITH ALTERNATING SOURCE
Authors: JI YING-HUA , HU JU-JU , LIU QING , ZOU DAN
Published: December 2006

In this paper, we examine a mesoscopic LC circuit with alternating source and solve its time-dependent Schrödinger equation by selecting a proper Hermitian invariant operator. We study LR geometric phase in mesoscopic circuit system. Our results indicate that LR geometric phase is present at all times. In the evolution of the circuit system, it is a geometric phase factor accumulated by the wavefunction of external source's interaction with circuit system after nonadiabatic and noncyclic evolution. Its property lies in that it depends on the evolution path of the system wavefunction in the parameter space.
DIMERS ON TWO-DIMENSIONAL LATTICES
Authors: WU F. Y.
Published: December 2006

We consider close-packed dimers, or perfect matchings, on two-dimensional regular lattices. We review known results and derive new expressions for the free energy, entropy, and the molecular freedom of dimers for a number of lattices including the simple-quartic, honeycomb, triangular, kagome, 3-12 and its dual, and 4-8 and its dual Union Jack lattices. The occurrence and nature of phase transitions are also elucidated and discussed in each case.
AN EFFICIENT PROGRESSIVE IMAGE TRANSMISSION SCHEME FOR CHINESE CALLIGRAPHY
Authors: CHANG CHING-YUN , LIN IUON-CHANG
Published: December 2006

We invented a progressive image transmission scheme that is used for transmitting Chinese calligraphy. The scheme employs the property of simple colors of calligraphy images to design a method of transmitting images phase by phase. Overall, our scheme can achieve the following two goals. One is compressing the image data to reduce the transmission time while the other is gaining less response time by using progressive image transmission. Furthermore, the recovered image still maintains the colors of the seals with high image quality.
GENERALIZED PARTICLE MODEL USED FOR DATA CLUSTERING
Authors: SHUAI DIANXUN , FANGLIANG XUE
Published: December 2006

Data clustering has been widely used in many areas, such as data mining, statistics, machine learning and so on. A variety of clustering approaches have been proposed so far, but most of them are not qualified to quickly cluster a large-scale high-dimensional database. This paper is devoted to a novel data clustering approach based on a generalized particle model (GPM). The GPM transforms the data clustering process into a stochastic process over the configuration space on a GPM array. The proposed approach is characterized by the self-organizing clustering and many advantages in terms of the insensitivity to noise, quality robustness to clustered data, suitability for high-dimensional and massive data sets, learning ability, openness and easier hardware implementation with the VLSI systolic technology. The analysis and simulations have shown the effectiveness and good performance of the proposed GPM approach to data clustering.
SVM-BASED PHONEME CLASSIFICATION AND LIP SHAPE REFINEMENT IN REAL-TIME LIP-SYNCH SYSTEM
Authors: KO HANSEOK , HAN DAVID K.
Published: December 2006

In this paper, we present a real time lip-synch system that activates 2-D avatar's lip motion in synch with incoming speech utterance. To achieve the real time operation of the system, the processing time was minimized by "merge and split" procedures resulting in coarse-to-fine phoneme classification. At each stage of phoneme classification, the support vector machine (SVM) method was applied to reduce the computational load while maintaining the desired accuracy. The coarse-to-fine phoneme classification, is accomplished via two_stages of feature extraction: in the first stage, each speech frame is acoustically analyzed for three classes of lip opening using Mel Frequency Cepstral Coefficients (MFCC) as a feature; in the second stage, each frame is further refined for detailed lip shape using formant information. The method was implemented in 2-D lip animation and it was demonstrated that the system was effective in accomplishing real-time lip-synch. This approach was tested on a PC using the Microsoft Visual Studio with an Intel Pentium IV 1.4 Giga Hz CPU and 384 MB RAM. It was observed that the methods of phoneme merging and SVM achieved about twice the speed in recognition than the method employing the Hidden Markov Model (HMM). A typical latency time per a single frame observed using the proposed method was in the order of 18.22 milliseconds while an HMM method under identical conditions resulted about 30.67 milliseconds.
REDUCING THE OVERFITTING OF ADABOOST BY CONTROLLING ITS DATA DISTRIBUTION SKEWNESS
Authors: SUN YIJUN , TODOROVIC SINISA , LI JIAN
Published: December 2006

AdaBoost rarely suffers from overfitting problems in low noise data cases. However, recent studies with highly noisy patterns have clearly shown that overfitting can occur. A natural strategy to alleviate the problem is to penalize the data distribution skewness in the learning process to prevent several hardest examples from spoiling decision boundaries. In this paper, we pursue such a penalty scheme in the mathematical programming setting, which allows us to define a suitable classifier soft margin. By using two smooth convex penalty functions, based on Kullback–Leibler divergence (KL) and l2 norm, we derive two new regularized AdaBoost algorithms, referred to as AdaBoostKL and AdaBoostNorm2, respectively. We prove that our algorithms perform stage-wise gradient descent on a cost function, defined in the domain of their associated soft margins. We demonstrate the effectiveness of the proposed algorithms through experiments over a wide variety of data sets. Compared with other regularized AdaBoost algorithms, our methods achieve at least the same or better performance.
CLUSTERING ALGORITHM RESEARCH BASED ON SELF-ORGANIZING FEATURE MAPS NETWORKS
Authors: WEN JUNHAO , WU HONGYAN , WU ZHONGFU , TANG YUANYAN , HE GUANGHUI
Published: December 2006

Self-organizing feature maps (SOFM) can learn both the distribution and topology of the input vectors they are trained on. According to this characteristic, we construct neural networks with a family of self-organizing feature maps to cluster the input data space. The proposed algorithm in this paper defines a novel similarity measure, topological similarity, and employs some new concepts, such as SOFM family, UsageFactor. The clustering algorithm handles the clusters with arbitrary shapes and avoid the limitations of the conventional clustering algorithms. We conclude our paper by several experiments with synthetic and standard data set of different characteristics, which show good performance of the proposed algorithm.
FACE AND EYE DETECTION FROM HEAD AND SHOULDER IMAGE ON MOBILE DEVICES
Authors: LAI JIAN HUANG , YUEN PONG C.
Published: December 2006

With the advance of semiconductor technology, the current mobile devices support multimodal input and multimedia output. In turn, human computer communication applications can be developed in mobile devices such as mobile phone and PDA. This paper addresses the research issues of face and eye detection on mobile devices. The major obstacles that we need to overcome are the relatively low processor speed, low storage memory and low image (CMOS senor) quality. To solve these problems, this paper proposes a novel and efficient method for face and eye detection. The proposed method is based on color information because the computation time is small. However, the color information is sensitive to the illumination changes. In view of this limitation, this paper proposes an adaptive Illumination Insensitive (AI2) Algorithm, which dynamically calculates the skin color region based on an image color distribution. Moreover, to solve the strong sunlight effect, which turns the skin color pixel into saturation, a dual-color-space model is also developed. Based on AI2algorithm and face boundary information, face region is located. The eye detection method is based on an average integral of density, projection techniques and Gabor filters. To quantitatively evaluate the performance of the face and eye detection, a new metric is proposed. 2158 head & shoulder images captured under uncontrolled indoor and outdoor lighting conditions are used for evaluation. The accuracy in face detection and eye detection are 98% and 97% respectively. Moreover, the average computation time of one image using Matlab code in Pentium III 700MHz computer is less than 15 seconds. The computational time will be reduced to tens hundreds of millisecond (ms) if low level programming language is used for implementation. The results are encouraging and show that the proposed method is suitable for mobile devices.
SOBOLEV REGULARITY OF INVARIANT MEASURES FOR GENERALIZED ORNSTEIN–UHLENBECK OPERATORS
Authors: ES-SARHIR ABDELHADI
Published: December 2006

This paper deals with the regularity of an invariant measure μ associated to a class of generalized Ornstein–Uhlenbeck operators. Regularity here means that μ is absolutely continuous with respect to a properly chosen Gaussian reference measure σ on a separable Hilbert space H. Moreover, the square root of its Radon–Nikodym derivative ρ should belong to some directional Sobolev space [Formula: see text].
SQUARES OF WHITE NOISE, SL(2, ℂ) AND KUBO–MARTIN–SCHWINGER STATES
Authors: PROKHORENKO DMITRY V.
Published: December 2006

We investigate the structure of Kubo–Martin–Schwinger (KMS) states on some extension of the universal enveloping algebra of SL (2, ℂ). We find that there exists a one-to-one correspondence between the set of all covariant KMS states on this algebra and the set of all probability measures dμ on the real half-line [0, +∞), which decrease faster than any inverse polynomial. This problem is connected to the problem of KMS states on square of white noise algebra.
Glucagon-like peptide-1 stimulates GABA formation by pancreatic β-cells at the level of glutamate decarboxylase
Authors: Wang Chen , Mao Rui , Van De Casteele Mark , Pipeleers Daniel , Ling Zhidong
Published: December 2006

Pancreatic β-cells are the major extraneural site of glutamate decarboxylase expression (GAD). During culture of isolated β-cells, the GAD product γ-aminobutyrate (GABA) is rapidly released in the medium, independently of insulin. It is considered as a possible mediator of β-cell influences on α-cells, acinar cells, and/or infiltrating lymphocytes. In this perspective, we investigated the regulation of GABA release by rat β-cells during a 24-h culture period. Glucose was previously reported to inhibit GABA release by diverting cellular GABA to mitochondrial breakdown through activation of GABA transferase (GABA-T). In the present study, glucagon-like peptide-1 (GLP-1) was shown to stimulate GABA formation at the level of GAD, its effect being suppressed by the GAD inhibitor allylglycine and remaining unaltered by the GABA-T inhibitor γ-vinyl-GABA. The stimulatory action of GLP-1 is cAMP dependent, being reproduced by the adenylate cyclase activator forskolin and the cAMP analog N6-benzoyladenosine-3′,5′-cAMP and inhibited by a PKA inhibitor. It is dependent on protein synthesis and associated with an increased expression of GAD67 but not GAD65. The GLP-1-induced stimulation of GAD activity in β-cells can elevate medium GABA levels in conditions of glucose-driven intracellular GABA breakdown and thus maintain GABA-mediated β-cell influences on neighboring cells.
Downregulation of the V2 vasopressin receptor in dehydration: mechanisms and role of renal prostaglandin synthesis
Authors: Machida Kenji , Wakamatsu Shiho , Izumi Yuichiro , Yosifovska Tatjana , Matsuzaki Takanobu , Nakayama Yushi , Kohda Yukimasa , Inoue Takeaki , Saito Hideyuki , Tomita Kimio , Nonoguchi Hiroshi
Published: December 2006

The vasopressin-aquaporin 2 system plays a key role in urine concentration in dehydration. In contrast to the upregulation of aquaporin 2, the downregulation of the vasopressin V2 receptor in dehydration is known. We investigated the mechanisms of this downregulation in dehydration using reverse transcription-competitive polymerase chain reaction (RT-competitive PCR) and Western blot analysis. The incubation of microdissected inner medullary collecting ducts (IMCDs) in a hypertonic medium or with vasopressin stimulated V2 receptor mRNA and protein expression, showing that dehydration-induced hyperosmolality in renal medulla and increased plasma arginine vasopressin (AVP) concentration should upregulate V2 receptor. The presence of inhibitory factors on the V2 receptor in dehydration was suggested. Prostaglandin E2(PGE2) is known to inhibit AVP-induced cAMP production and to increase production in dehydration. PGE2slightly stimulated V2 receptor mRNA expression in IMCD in vitro. However, PGE2inhibited V2 receptor mRNA expression in IMCD in the presence of 10−9M vasopressin. The blockade of PGE2synthesis by indomethacin in dehydrated rats increased V2 receptor protein expression after 24–48 h with an early increase in V2 receptor mRNA expression. In summary, these data suggest that increased production of PGE2in renal medulla plays a key role in the downregulation of V2 receptor in dehydration.
Effects of acute and chronicl-arginine treatment in experimental hyperuricemia
Authors: Sánchez-Lozada Laura G. , Tapia Edilia , López-Molina Rubén , Nepomuceno Tomás , Soto Virgilia , Ávila-Casado Carmen , Nakagawa Takahiko , Johnson Richard J. , Herrera-Acosta Jaime , Franco Martha
Published: December 2006

Experimental hyperuricemia (HU) results in preglomerular arteriolopathy, cortical vasoconstriction, and glomerular hypertension. Recently, uric acid has been shown to induce endothelial dysfunction. We therefore studied the effect of acute and chronic administration of l-arginine (a substrate for endothelial nitric oxide synthase) on the renal hemodynamic and vascular structural alterations induced by HU. To induce HU, oxonic acid (OA; 750 mg·kg−1·day−1) was administered in male Sprague-Dawley rats. To study the acute effect of arginine, nine rats received l-arginine (l-Arg; 15 mg·kg−1·min−1) during micropuncture. To elucidate the chronic effect of l-Arg, OA + 1% l-Arg ( n = 8) and OA + 2.5% l-Arg ( n = 6; drinking water) were evaluated throughout the 5-wk period. Eight normal control (N), and eight OA, rats were also studied. Kidneys were fixed by perfusion and afferent arteriole morphology was evaluated. HU rats developed the renal functional and structural alterations described and had suppressed urinary excretion of NO2−/NO3−. Acute stimulation of nitric oxide (NO) synthesis markedly increased urinary NO2−/NO3−, lowered systemic blood pressure, and relieved cortical vasoconstriction despite a significant increment of glomerular hypertension and afferent arteriole damage. Increasing doses of chronic l-Arg were associated with increasing excretion of urinary NO2−/NO3−, reduction of systemic hypertension, and prevention of cortical vasoconstriction (2.5% l-Arg). In addition, both doses prevented glomerular hypertension and preglomerular arteriolopathy. Thus an acute relief of renal vasoconstriction in the setting of afferent arteriole damage cannot reverse glomerular hypertension, likely due to impairment in preglomerular autoregulation. On the other hand, chronic l-Arg preserved arteriolar structures probably mediated by the antiproliferative effect of NO on vascular smooth muscle cells.
Transactivation of the IGF-1R by aldosterone
Authors: Holzman Jennifer L. , Liu Lian , Duke Billie Jeanne , Kemendy Alexandra E. , Eaton Douglas C.
Published: December 2006

Activation of epithelial sodium channels (ENaC) by aldosterone, insulin, or insulin-like growth factor-1 (IGF-1) in renal epithelial cells (including the Xenopus laevis renal cell line A6) appears to share some common signaling elements subsequent to the initial insulin or IGF-1 receptor activation. Previously, the convergence point for insulin or IGF-1 and aldosterone signaling was assumed to be downstream of the receptor at the level of phosphatidylinositol 3-kinase (PI3-K); however, this study shows aldosterone directly transactivates the IGF-1 receptor (IGF-1R). In A6 cells, 10-min exposure to aldosterone increased the phosphorylation of the IGF-1 receptor, insulin receptor substrate-1 (IRS-1), and Akt (PKB). Furthermore, aldosterone activated PI3-K and phosphorylation of the most downstream element, Akt, was blocked by the specific PI3-K inhibitor LY-294002. Transactivation requires aldosterone binding to the mineralocorticoid/glucocorticoid receptor and does not require transcription.
Thiazolidinedione ameliorates renal injury in experimental diabetic rats through anti-inflammatory effects mediated by inhibition of NF-κB activation
Authors: Ohga Sakiko , Shikata Kenichi , Yozai Kosuke , Okada Shinichi , Ogawa Daisuke , Usui Hitomi , Wada Jun , Shikata Yasushi , Makino Hirofumi
Published: December 2006

Thiazolidinedione (TZD), a ligand for peroxisome proliferator-activated receptor-γ (PPAR-γ), exerts anti-inflammatory effects independently of the insulin-sensitizing effect. In the present study, we tested the hypothesis that TZD prevents the progression of diabetic nephropathy by modulating the inflammatory process. Five-week-old Sprague-Dawley rats were divided into three groups: 1) nondiabetic control rats (non-DM), 2) diabetic rats (DM), and 3) diabetic rats treated with pioglitazone (DM+pio). Diabetes was induced by injection with streptozotocin (STZ). The DM+pio group received 0.0002% pioglitazone mixed in chow for 8 wk after induction of diabetes. Blood glucose and HbA1c were elevated in diabetic rats but did not change by treatment with pioglitazone. Pioglitazone reduced urinary albumin excretion and glomerular hypertrophy, suppressed the expression of transforming growth factor (TGF)-β, type IV collagen, and ICAM-1, and infiltration of macrophages in the kidneys of diabetic rats. Furthermore, renal NF-κB activity was increased in diabetic rats and reduced by pioglitazone. PPAR-γ was expressed in glomerular endothelial cells in the diabetic kidney and in cultured glomerular endothelial cells. High-glucose conditions increased the expression of ICAM-1 and the activation of NF-κB in cultured glomerular endothelial cells. These changes were reduced by pioglitazone, ciglitazone, and pyrrolidine dithiocarbamate, an inhibitor of NF-κB. However, pioglitazone did not show the changes in the presence of PPAR-γ antagonist GW9662. Our results suggest that the preventive effects of pioglitazone may be mediated by its anti-inflammatory actions, including inhibition of NF-κB activation, ICAM-1 expression, and macrophage infiltration in the diabetic kidney.
Parathyroid hormone stimulates endothelial expression of atherosclerotic parameters through protein kinase pathways
Authors: Rashid Gloria , Bernheim Jacques , Green Janice , Benchetrit Sydney
Published: December 2006

Parathyroid hormone (PTH), the major systemic calcium-regulating hormone, has been linked to uremic vascular changes. Considering the possible deleterious action of PTH on vascular structures, it seemed logical to evaluate the impact of PTH on the receptor of advanced glycation end products (RAGE) and interleukin 6 (IL-6) mRNA and protein expression, taking into account that such parameters might be involved in the pathogenesis of vascular calcification, atherosclerosis, and/or arteriolosclerosis. Human umbilical vein cord endothelial cells (HUVEC) were stimulated for 24 h with 10−12–10−10mol/l PTH. The mRNA expression of RAGE and IL-6 was established by reverse transcriptase/PCR techniques. RAGE protein levels were determined by Western blot and IL-6 secretion was measured by ELISA. The pathways by which PTH may have an effect on HUVEC functions were evaluated. PTH (10−11–10−10mol/l) significantly increased RAGE mRNA and protein expression. PTH also significantly increased IL-6 mRNA expression without changes at protein levels. The addition of protein kinase (PKC or PKA) inhibitors or nitric oxide (NO) synthase inhibitors significantly reduced the RAGE and IL-6 mRNA expression and the RAGE protein expression. PTH stimulates the mRNA expressions of RAGE and IL-6 and the protein expression of RAGE. These stimulatory effects are probably through PKC and PKA pathways and are also NO dependent. Such data may explain the possible impact of PTH on the atherosclerotic and arteriosclerotic progression.
Role of matrix metalloproteinases in renal pathophysiologies
Authors: Catania J. M. , Chen G. , Parrish A. R.
Published: December 2006

Matrix metalloproteinases (MMPs) are a large family of proteinases that remodel extracellular matrix (ECM) components and cleave a number of cell surface proteins. MMP activity is regulated via a number of mechanisms, including inhibition by tissue inhibitors of metalloproteinases (TIMPs). Originally thought to cleave only ECM proteins, MMP substrates are now known to include signaling molecules (growth factor receptors) and cell adhesion molecules. Recent data suggest a role for MMPs in a number of renal pathophysiologies, both acute and chronic. This review will focus on the expression and localization of MMPs and TIMPs in the kidney, as well as summarizing the current information linking these proteins to acute kidney injury, glomerulosclerosis/tubulointerstitial fibrosis, chronic allograft nephropathy, diabetic nephropathy, polycystic kidney disease, and renal cell carcinoma.
A metabolomic comparison of urinary changes in type 2 diabetes in mouse, rat, and human
Authors: Salek R. M. , Maguire M. L. , Bentley E. , Rubtsov D. V. , Hough T. , Cheeseman M. , Nunez D. , Sweatman B. C. , Haselden J. N. , Cox R. D. , Connor S. C. , Griffin J. L.
Published: December 2006

Type 2 diabetes mellitus is the result of a combination of impaired insulin secretion with reduced insulin sensitivity of target tissues. There are an estimated 150 million affected individuals worldwide, of whom a large proportion remains undiagnosed because of a lack of specific symptoms early in this disorder and inadequate diagnostics. In this study, NMR-based metabolomic analysis in conjunction with multivariate statistics was applied to examine the urinary metabolic changes in two rodent models of type 2 diabetes mellitus as well as unmedicated human sufferers. The db/db mouse and obese Zucker ( fa/fa) rat have autosomal recessive defects in the leptin receptor gene, causing type 2 diabetes. 1H-NMR spectra of urine were used in conjunction with uni- and multivariate statistics to identify disease-related metabolic changes in these two animal models and human sufferers. This study demonstrates metabolic similarities between the three species examined, including metabolic responses associated with general systemic stress, changes in the TCA cycle, and perturbations in nucleotide metabolism and in methylamine metabolism. All three species demonstrated profound changes in nucleotide metabolism, including that of N-methylnicotinamide and N-methyl-2-pyridone-5-carboxamide, which may provide unique biomarkers for following type 2 diabetes mellitus progression.
Functional nonsynonymous single nucleotide polymorphisms from the TGF-β protein interaction network
Authors: Savas Sevtap , Taylor Ian W. , Wrana Jeff L. , Ozcelik Hilmi
Published: December 2006

Protein complexes mediated by protein-protein interactions are essential for many cellular functions. Transforming growth factor (TGF)-β signaling involves a cascade of protein-protein interactions and malfunctioning of this pathway has been implicated in human diseases. Using an in silico approach, we analyzed the naturally occurring human genetic variations from the proteins involved in the TGF-β signaling (10 TGF-β proteins and 242 other proteins interacting with them) to identify the ones that have potential biological consequences. All proteins were searched in the dbSNP database for the presence of nonsynonymous single nucleotide polymorphisms (nsSNPs). A total of 118 validated nsSNPs from 63 proteins were retrieved and analyzed in terms of 1) evolutionary conservation status, 2) being located in a functional protein domain or motif, and 3) altering putative protein motif or phosphorylation sites. Our results indicated the presence of 31 nsSNPs that occurred at evolutionarily conserved residues, 37 nsSNPs were located in protein domains, motifs, or repeats, and 46 nsSNPs were predicted to either create or abolish putative protein motifs or phosphorylation sites. We undertook this study to analyze the human genetic variations that can affect the protein function and the TGF-β signaling. The nsSNPs reported in here can be characterized by experimental approaches to elucidate their exact biological roles and whether they are related to human disease.
Shape of Field-Induced Nanostructures Formed by STM
Authors: Gangopadhyay Subhashis , Kar Asit Kumar , Mathur Balbir Kumar
Published: December 2006

Creation of controlled and reproducible nanostructures on material surfaces using scanning tunneling microscope is a novel technique, which can be used for a variety of applications. We have examined the shape of the nanostructures so formed on the gold film using tungsten tip and examined the formation parameters, which govern their shape and size. During our investigations it is found that the reproducibility of mound formation can reach up to 90%under optimum operating conditions, whereas the pit formation can be made with almost 100%reproducibility. Formation mechanism of such nanostructures is also discussed.
A Note on Asymptotic Contractions
Authors: Arav Marina , Castillo Santos Francisco Eduardo , Reich Simeon , Zaslavski Alexander J
Published: December 2006

We provide sufficient conditions for the iterates of an asymptotic contraction on a complete metric space "Equation missing" to converge to its unique fixed point, uniformly on each bounded subset of "Equation missing".
Improved Image Fusion in PET/CT Using Hybrid Image Reconstruction and Super‐Resolution
Authors: Kennedy John A. , Israel Ora , Frenkel Alex , Bar-Shalom Rachel , Azhari Haim
Published: December 2006

Purpose. To provide PET/CT image fusion with an improved PET resolution and better contrast ratios than standard reconstructions. Method. Using a super‐resolution algorithm, several PET acquisitions were combined to
improve the resolution. In addition, functional PET data was smoothed with a hybrid
computed tomography algorithm (HCT), in which anatomical edge information taken from
the CT was employed to retain sharper edges. The combined HCT and super‐resolution
technique were evaluated in phantom and patient studies using a clinical PET scanner.
Results. In the phantom studies, 3 mm 18F‐FDG sources were resolved. PET contrast ratios
improved (average: 54%, range: 45%–69%) relative to the standard reconstructions. In the
patient study, target‐to‐background ratios also improved (average: 34%, range: 17%–47%).
Given corresponding anatomical borders, sharper edges were depicted.
Conclusion. A new method incorporating super‐resolution and HCT for
fusing PET and CT images has been developed and shown to provide higher‐resolution metabolic images.
ESTERR‐PRO: A Setup Verification Software System Using Electronic Portal Imaging
Authors: Asvestas Pantelis A. , Delibasis Konstantinos K. , Mouravliansky Nikolaos A. , Matsopoulos George K.
Published: December 2006

The purpose of the paper is to present and evaluate the performance of a new software‐based registration system for patient setup verification, during radiotherapy, using electronic portal images. The estimation of setup errors, using the proposed system, can be accomplished by means of two alternate registration methods. (a) The portal image of the current fraction of the treatment is registered directly with the reference image (digitally reconstructed radiograph (DRR) or simulator image) using a modified manual technique. (b) The portal image of the current fraction of the treatment is registered with the portal image of the first fraction of the treatment (reference portal image) by applying a nearly automated technique based on self‐organizing maps, whereas the reference portal has already been registered with a DRR or a simulator image. The proposed system was tested on phantom data and on data from six patients. The root mean square error (RMSE) of the setup estimates was 0.8 ± 0.3 (mean value ± standard deviation) for the phantom data and 0.3 ± 0.3 for the patient data, respectively, by applying the two methodologies. Furthermore, statistical analysis by means of the Wilcoxon nonparametric signed test showed that the results that were obtained by the two methods did not differ significantly (Pvalue >0.05).
Rugometric and Microtopographic Inspection of Cr–Cr2O3Cermet Solar Absorbers
Authors: Costa Manuel F. M. , Teixeira V.
Published: December 2006

The development of new efficient and cost effective solar energy collectors and converters either quantum or thermal attracts great attention and effort in a number of research laboratories all over the world. Cr–Cr2O3cermet PVD coatings can be successfully employed in thermal converters. Their energy conversion efficiency depends on their chemical and physical structural characteristics and related optical properties like reflectance, emittance, solar light absorption, or absorptance and transmittance. Parameters such as roughness and topographic characteristics of the produced coatings will greatly influence their relevant optical properties. A careful evaluation of the coatings' roughness and their microtopographic inspection is fundamental. The Cr–Cr2O3cermet coatings sputter deposited on cooper and aluminium shows similar absorption (92%) but the first ones present a better emittance and higher waviness (over30%) with similar roughness. In comparison with commercially available solar panels with a slightly better absorption but worse emittance our coatings have a much lower waviness (∼150%) and roughly50%higher roughness.
General Formula for Estimation of Monthly Mean Global Solar Radiation in Different Climates on the South and North Coasts of Iran
Authors: Sabziparvar Ali A.
Published: December 2006

Using sunshine duration, cloud cover, relative humidity, average of maximum temperature, and ground albedo as the input of several radiation models, the monthly average daily solar radiation on horizontal surface in various coastal cities of the South (25.23∘N) and the North (38.42∘N) of Iran are estimated. Several radiation models are tested and further are revised by taking into consideration the effects of relative humidity, ground albedo, and Sun-Earth distance. Model validation is performed by using up to 13 years (1988–2000) of daily solar observations. Errors are calculated using MBE, MABE, MPE, and RMSE statistical criteria (see nomenclature) and further a general formula which estimates the global radiation in different climates of coastal regions is suggested. The proposed method shows a good agreement (less than7%deviation) with the long-term pyranometric data. In comparison with other works done so far, the suggested method performs a higher degree of accuracy for those of two regions. The model results can be extended to other locations in coastal regions where solar data are not available.