bluuebunny/crossref_metadata_2025 huggingface dataset:
Compressed wavefield extrapolation
Authors: Lin Tim T. , Herrmann Felix J.
Published: September 2007

An explicit algorithm for the extrapolation of one-way wavefields is proposed that combines recent developments in information theory and theoretical signal processing with the physics of wave propagation. Because of excessive memory requirements, explicit formulations for wave propagation have proven to be a challenge in 3D. By using ideas from compressed sensing, we are able to formulate the (inverse) wavefield extrapolation problem on small subsets of the data volume, thereby reducing the size of the operators. Compressed sensing entails a new paradigm for signal recovery that provides conditions under which signals can be recovered from incomplete samplings by nonlinear recovery methods that promote sparsity of the to-be-recovered signal. According to this theory, signals can be successfully recovered when the measurement basis is incoherent with the representa-tion in which the wavefield is sparse. In this new approach, the eigenfunctions of the Helmholtz operator are recognized as a basis that is incoherent with curvelets that are known to compress seismic wavefields. By casting the wavefield extrapolation problem in this framework, wavefields can be successfully extrapolated in the modal domain, despite evanescent wave modes. The degree to which the wavefield can be recovered depends on the number of missing (evanescent) wavemodes and on the complexity of the wavefield. A proof of principle for the compressed sensing method is given for inverse wavefield extrapolation in 2D, together with a pathway to 3D during which the multiscale and multiangular properties of curvelets, in relation to the Helmholz operator, are exploited. The results show that our method is stable, has reduced dip limitations, and handles evanescent waves in inverse extrapolation.
Predicting and monitoring long-term compaction in unconsolidated reservoir sands using a dual power law model
Authors: Hagin Paul N. , Zoback Mark D.
Published: September 2007

We propose a model for predicting the long-term creep compaction of unconsolidated sand reservoirs prior to significant depletion. The model is based upon linear viscoelasticity theory, whereby deformation is decoupled into instantaneous and time-dependent components. The instantaneous component of deformation is modeled using a power law function of effective pressure. Model parameters are solved by conducting a constant strain-rate laboratory experiment. The time-dependent deformation is modeled using a power law function of time. Associated model parameters are solved by conducting a creep-strain test at the anticipated in-situ effective pressure. In total, application of the model involves measurement of three model parameters obtained by conducting two different laboratory experiments. We illustrate the model utilizing samples from unconsolidated sand reservoirs in the Wilmington field in California and an offshore field in the Gulf of Mexico. We show that the stiffness change associated with the porosity reduction predicted by the model is large and could be monitored using P-wave velocity. This should make compaction observable with 4D seismic surveys of the example fields.
Eulerian Gaussian beams for high-frequency wave propagation
Authors: Leung Shingyu , Qian Jianliang , Burridge Robert
Published: September 2007

We design an Eulerian Gaussian beam summation method for solving Helmholtz equations in the high-frequency regime. The traditional Gaussian beam summation method is based on Lagrangian ray tracing and local ray-centered coordinates. We propose a new Eulerian formulation of Gaussian beam theory which adopts global Cartesian coordinates, level sets, and Liouville equations, yielding uniformly distributed Eulerian traveltimes and amplitudes in phase space simultaneously for multiple sources. The time harmonic wavefield can be constructed by summing up Gaussian beams with ingredients provided by the new Eulerian formulation. The conventional Gaussian beam summation method can be derived from the proposed method. There are three advantages of the new method: (1) We have uniform resolution of ray distribution. (2) We can obtain wavefields excited at different sources by varying only source locations in the summation formula. (3) We can obtain wavefields excited at different frequencies by varying only frequencies in the summation formula. Numerical experiments indicate that the Gaussian beam summation method yields accurate asymptotic wavefields even at caustics. The new method may be used for seismic modeling and migration.
Vp ∕ Vs ratio versus differential stress and rock consolidation — A comparison between rock models and time-lapse AVO data
Authors: Duffaut Kenneth , Landrø Martin
Published: September 2007

The compressional to shear wave velocity ratio [Formula: see text] is an important parameter in seismic amplitude versus offset (AVO) analysis, and this parameter plays a key role especially for lithology and fluid prediction methods. The P-wave velocity is a key parameter in traditional pressure prediction methods, because overpressure often results in a velocity reduction. However, for AVO-based pore pressure prediction methods, one expects that the [Formula: see text] ratio also is a key parameter. The Hertz-Mindlin geomechanical model predicts a constant [Formula: see text] ratio as the differential stress changes in a dry package of identical spheres. Ultrasonic core measurements show increased [Formula: see text] ratios as the differential stress decreases, especially for unconsolidated wet sands. Thus, one is likely to assume that the [Formula: see text] ratio is dependent on rock consolidation. By combining the Hertz-Mindlin model with the Gassmann model, we show how to obtain a sim-ple rock-physics framework including both the differential stress and the degree of rock consolidation. We use the number of grain-to-grain contacts (coordination number) to represent the rock consolidation. For two field examples, we calibrate this consolidation parameter to in-situ stress conditions, then compare the predicted [Formula: see text] ratios for the overpressured reservoir conditions with observed time-lapse AVO changes. The correspondence between modeled and AVO-estimated [Formula: see text] ratios is good within the assumed accuracy of the real time-lapse AVO changes. In both cases, we observe an increase in the [Formula: see text] ratio as the differential stress decreases. In the first case, a pore pressure increase of [Formula: see text] is measured, whereas the other case shows a pressure increase of approximately [Formula: see text]. The first reservoir represents a low-to-medium-consolidated sandstone reservoir of 33% porosity on average, whereas the second reservoir is a more consolidated sand with similar porosities (30%).
Application of simulated annealing inversion on high-frequency fundamental-mode Rayleigh wave dispersion curves
Authors: Pei Donghong , Louie John N. , Pullammanappallil Satish K.
Published: September 2007

The simulated annealing (SA) inversion technique has been successfully applied for solving various nonlinear geophysical problems. Following previous developments, we modified the SA inversion, yielding 1D shallow S-wave velocity profiles from high frequency fundamental-mode Rayleigh dispersion curves, and validated the inversion with blind tests. Unlike previous applications of SA, this study draws random numbers from a standard Gaussian distribution. The numbers simultaneously perturb both S-wave velocities and the layer thickness of models. The annealing temperature is gradually decreased following a polynomial-time cooling schedule. Phase velocities are calculated using the reflectivity-transmission coefficient method. The reliability of the model resulting from our implementation is evaluated by statistically calculating the expected values of model parameters and their covariance matrices. Blind tests on two field and 12 synthetic Rayleigh dispersion data sets show that our SA implementation works well for S-wave velocity inversion of dispersion curves from high-frequency fundamental-mode Rayleigh waves. Blind estimates of layer S-wave velocities fall within one standard deviation of the velocities of the original synthetic models in 78% of cases.
Noise reduction and data recovery for a VLF-EM survey using a nonlinear decomposition method
Authors: Jeng Yih , Lin Ming-Juin , Chen Chih-Sung , Wang Yu-Huai
Published: September 2007

Geologic noise and background electromagnetic (EM) waves often degrade the quality of very low frequency electromagnetic (VLF-EM) data. To retrieve signals with significant geologic information, we used a new nonlinear decomposition technique called the empirical mode decomposition (EMD) method with the Hilbert transform. We conducted a 2D resistivity model study that included inversion of the synthetic data to test the accuracy and capabilities of this method. Next, we applied this method to real data obtained from a field experiment and a geologic example. The filtering procedure for real data starts with applying the EMD method to decompose the VLF data into a series of intrinsic mode functions that admit a well-behaved Hilbert transform. With the Hilbert transform, the intrinsic mode functions yielded a spectrogram that presents an energy-wavenumber-distance distribution of the VLF data. We then examined the decomposed data and their spectrogram to determine the noise components, which we eliminated to obtain more reliable VLF data. The EMD-filtered data and their associated spectrograms indicated the successful application of this method. Because VLF data are recorded as a complex function of the real variable distance, the in-phase and quadrature parts are complementary components of each other and could be a Hilbert transform pair if the data are analytical and noise free. Therefore, by comparing the original data set with the one obtained from the Hilbert transform, we could evaluate data quality and could even replace the original with its Hilbert transform counterpart with acceptable accuracy. By application of both this technique and conventional methods to real data in this study, we have shown the superiority of this new method and have obtained a more reliable earth model by inverting the EMD-filtered data.
Computational methods for large-scale 3D acoustic finite-difference modeling: A tutorial
Authors: Etgen John T. , O’Brien Michael J.
Published: September 2007

We present a set of methods for modeling wavefields in three dimensions with the acoustic-wave equation. The primary applications of these modeling methods are the study of acquisition design, multiple suppression, and subsalt imaging for surface-streamer and ocean-bottom recording geometries. We show how to model the acoustic wave equation in three dimensions using limited computer memory, typically using a single workstation, leading to run times on the order of a few CPU hours to a CPU day. The structure of the out-of-core method presented is also used to improve the efficiency of in-core modeling, where memory-to-cache-to-memory data flow is essentially the same as the data flow for an out-of-core method. Starting from the elastic-wave equation, we develop a vector-acoustic algorithm capable of efficiently modeling multicomponent data in an acoustic medium. We show that data from this vector-acoustic algorithm can be used to test upgoing/downgoing separation of P-waves recorded by ocean-bottom seismic acquisition.
Characterizing a GPR antenna system by near-field electric field measurements
Authors: Streich Rita , van der Kruk Jan
Published: September 2007

A method to determine current distributions on resistively loaded Wu-King-type antennas from sparse near-field measurements of the electric field is introduced. We use a parametric formulation of current flow and invert the measured data to determine the characteristic antenna parameters and input voltage wavelets that best explain the measured electric-field data. We compare modeled and measured electric-field data to show that our inversion method yields reasonable results and that our antenna model provides a means to correct for the effects of an antenna’s finite length in migration/imaging algorithms. By modifying the description of the current distribution, our method may be adapted for various antenna types.
Phase velocity approximation in finely layered sediments
Authors: Stovas Alexey
Published: September 2007

The problem addressed here is to derive the approximation of the phase velocity function for wave propagation through a stack of elastic layers. The approximation takes into account multiple scattering in a finely layered medium and depends on a limited number of parameters.
3D baseline seismics at Ketzin, Germany: The C O2 SINK project
Authors: Juhlin Christopher , Giese Rüdiger , Zinck-Jørgensen Kim , Cosma Calin , Kazemeini Hesam , Juhojuntti Niklas , Lüth Stefan , Norden Ben , Förster Andrea
Published: September 2007

A 3D 25-fold seismic survey with a bin size of 12 by [Formula: see text] and about [Formula: see text] of subsurface coverage was acquired in 2005 near a former natural gas storage site west of Berlin, as part of the five-year EU funded [Formula: see text] project. Main objectives of the seismic survey were to verify earlier geologic interpretations of structure based on vintage 2D seismic and borehole data and to map, if possible, the reservoir pathways in which the [Formula: see text] will be injected at [Formula: see text] depth, as well as providing a baseline for future seismic surveys and planning of drilling operations. The uppermost [Formula: see text] are well imaged and show an anticlinal structure with an east-west striking central graben on its top that extendsdown to the target horizon. About [Formula: see text] of throwis seen on the bounding faults. No faults are imaged near the planned drill sites. Remnant gas, cushion and residual gas, is present near the top of the anticline in the depth interval of about [Formula: see text] and has a clear seismic signature; both higher amplitudes in the reservoir horizons and velocity pulldown are observed. Amplitude mapping of these remnant gas horizons shows that they do not extend as far south as the injection site, which is located on the southern flank of the anticline. Amplitude anomalies, gas chimneys along an east-west striking fault, show that the stored or remnant gas either has been or is presently migrating out of the reservoir formations. Summed amplitude mapping of the planned injection horizon indicates that this lithologically heterogeneous formation may be more porous at the injection site.
Pseudo-full-waveform inversion of borehole GPR data using stochastic tomography
Authors: Gloaguen Erwan , Giroux Bernard , Marcotte Denis , Dimitrakopoulos Roussos
Published: September 2007

Electromagnetic full-waveform tomography is computer intensive and requires good knowledge of antenna characteristics and ground coupling. As a result, ground-penetrating-radar tomography usually uses only the first wavelet’s arrival time and amplitude data. We propose to improve the classical approach by inverting multiple slowness and attenuation fields using stochastic tomography. To do so, we model the slowness and attenuation covariance functions to generate geostatistical simulations that are conditional to the arrival times, amplitudes, slowness, and attenuation observed along boreholes. We combine slowness and attenuation fields to compute conductivity and permittivity fields from which we model synthetic radar traces using a finite-difference time-domain full-waveform algorithm. Modeled traces that best match the measured ones correspond to the computed conductivity and permittivity fields that correlate best with the true physical properties of the ground. We apply the method to a synthetic example with known electric properties. We show that a combination of stochastic tomography and full-waveform modeling allows a better selection of permittivity fields close to the reference field, at a reasonable computing cost.
Extension of forward modeling phase-screen code in isotropic and anisotropic media up to critical angle
Authors: White James C. , Hobbs Richard W.
Published: September 2007

The computationally efficient phase-screen forward modeling technique is extended to allow investigation of nonnormal raypaths. The code is developed to accommodate all diffracted and converted phases up to critical angle, building on a geometric construction method. The new approach relies upon prescanning the model space to assess the complexity of each screen. The propagating wavefields are then divided as a function of horizontal wavenumber, and each subset is transformed to the spatial domain separately, carrying with it angular information. This allows both locally accurate 3D phase corrections and Zoeppritz reflection and transmission coefficients to be applied. The phase-screen code is further developed to handle simple anisotropic media. During phase-screen modeling, propagation is undertaken in the wavenumber domain where exact expressions for anisotropic phase velocities are available. Traveltimes and amplitude effects from a range of anisotropic shales are computed and compared with previous published results.
Heavy oils: Their shear story
Authors: Behura Jyoti , Batzle Mike , Hofmann Ronny , Dorgan John
Published: September 2007

Heavy oils are important unconventional hydrocarbon resources with huge reserves and are usually exploited through thermal recovery processes. These thermal recovery processes can be monitored using seismic techniques. Shear-wave properties, in particular, are expected to be most sensitive to the changes in the heavy-oil reservoir because heavy oils change from being solid-like at low temperatures to fluid-like at higher temperatures. To understand their behavior, we measure the complex shear modulus (and thus also the attenuation) of a heavy-oil-saturated rock and the oil extracted from it within the seismic frequency band in the laboratory. The modulus and quality factor [Formula: see text] of the heavy-oil-saturated rock show a moderate dependence on frequency, but are strongly influenced by temperature. The shear-wave velocity dispersion in these rocks is significant at steam-flooding temperatures as the oil inside the reservoir losesviscosity. At room temperatures, the extracted heavy oil supports a shear wave, but with increasing temperature, its shear modulus decreases rapidly, which translates to a rapid drop in the shear modulus of the heavy-oil-saturated rock as well. At these low to intermediate temperatures [Formula: see text], an attenuation peak corresponding to the viscous relaxation of the heavy oil is encountered (also resulting in significant shear-wave velocity dispersion, well described by the Cole-Cole model). Thus, shear-wave attenuation in heavy-oil rocks can be significantly large and is caused by both the melting and viscous relaxation of the heavy oil. At yet higher temperatures, the lighter components of the heavy oil are lost, making the oil stiffer and less attenuative. The dramatic changes in shear velocities and attenuation in heavy oils should be clearly visible in multicomponent seismic data, and suggest that these measurements can be qualitatively and quantitatively used in seismic monitoring of thermal recovery processes.
3D diffraction modeling of singly scattered acoustic wavefields based on the combination of surface integral propagators and transmission operators
Authors: Ayzenberg Milana A. , Aizenberg Arkady M. , Helle Hans B. , Klem-Musatov Kamill D. , Pajchel Jan , Ursin Bjørn
Published: September 2007

We present an improved method for modeling 3D acoustic wavefields scattered at smooth curved interfaces. The approach is based on a high-frequency approximation of surface integral propagators and a correct description of their boundary values in terms of transmission operators. The main improvement is a uniform local approximation of these operators in the form of effective reflection and transmission coefficients. We show that the effective coefficients represent a generalization of the plane-wave coefficients widely used in conventional seismic modeling, even for the case of curved reflectors, nonplanar wavefronts, and finite frequencies. The proposed method is capable of producing complex wave phenomenas, such as caustics, edge diffractions, and head waves. Seismograms modeled for even simple models reveal significant errors implicit in the plane-wave approximation. Comparison of modeling based on effective coefficients with the analytic solution reveals errors less than 4% in peak amplitude at seismic frequencies.
Elastic moduli of anisotropic clay
Authors: Bayuk Irina O. , Ammerman Mike , Chesnokov Evgeni M.
Published: September 2007

Clay minerals are important components in shales, controlling their elastic properties and anisotropy. The elasticity of crystalline clay minerals differs significantly from that of clay in situ because of the ability of clay particles to bind water. In the ma-jority of published works, only isotropic moduli for in situ clays are reported. However, anisotropy is inherent in the clay elas-ticity. We develop an inversion technique for determination of the stiffness tensor of in situ clay from the shale’s stiffness tensor. As an example, we obtain the stiffness tensor of a “water-clay” composite from the data on the water-saturated Greenhorn shale sample, whose clay composition consists of almost equal amounts of illite and smectite and comparable amounts of kaolinite and chlorite. The stiffness tensor of the water-clay composite is found for the Greenhorn shale with step-by-step inversion based upon an effective medium theory. The inversion usesa nonlinear optimization technique with bounds imposed on the estimated parameters. In the inversion, we apply different approaches of the effective medium theory using a published method referred to here as the generalized singular approxi-mation (GSA). The GSA method makes it possible to take into account the microstructure of shales. The resulting elasticity constants of the anisotropic (transversely isotropic) in situ clay composite are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] (in GPa); and the density equals [Formula: see text]. The Thomsen parameters for the clay composite are [Formula: see text], [Formula: see text], and [Formula: see text]. The elasticity constants found for this clay composite can be used in the theoretical analysis of shales that have a similar composition of clay but with different mineral compositions. The inversion technique developed can be used for general shale water-clay composites when the mineral composition and orientation of the clay platelets are known.
Decoupling of seismic reflectors and stratigraphic timelines: A modeling study of Tertiary strata from Svalbard
Authors: Johansen Ståle , Granberg Espen , Mellere Donatella , Arntsen Børge , Olsen Torben
Published: September 2007

In sequence stratigraphic interpretations, the key premise is that stratal surfaces effectively represent geologic timelines. When applied to seismic sections, the fundamental assumption is that primary reflections generally mimic stratigraphic timelines. The main objective of this study was to test how well key reflectors in a seismic section couple to timelines. To achieve the high level of ground control needed for such testing, we combined photogrammetry and traditional sedimentologic fieldwork to optimize the geologic model. We relied further on petrophysical analysis to derive a numerical model suitable for the simulation of seismic data. In spite of laterally discontinuous vertical-impedance contrasts (VICs), false seismic continuity was created, and we observed frequent decoupling of seismic reflectors and stratigraphic timelines. These observations demonstrate how the low-frequency seismic method fails to image normal complexity in a stratigraphic unit. A seismic correlation test showed that the interpreters made numerous mistakes and that such mistakes are very difficult to avoid. The failure of a fundamental assumption, as illustrated here, creates serious problems for the sequence stratigraphic concept when applied to detailed correlation analysis on seismic sections.
Comparison of two low-fold 3D geometries in Saudi Arabia
Authors: Crisi Peter A. , Hubbell Shelton E.
Published: September 2007

Two different 3D seismic survey geometries for relatively low-fold exploration objectives are compared. The sparse geometry (S3D) is executed in swaths using a crew with 960 active channels. It is fast and cost effective, and has been used extensively in Saudi Arabia. The low fold conventional geometry (LFC3D) is acquired in blocks using a crew with about 4000 active channels. LFC3D geometries offer better geophysical attributes, with less variability of offsets and azimuths between common midpoints (CMPs), improved statics control, and higher fold with less source effort. LFC3D geometries have greater flexibility for different survey objectives than S3D geometries, and are competitive with S3D geometries in terms of cost, speed, and data quality.
Seismic signature of a permeable, dual-porosity layer
Authors: Kozlov Evgenii
Published: September 2007

Of the key reservoir properties, permeability seems to be the most elusive. Since the middle of the 90s, various seismic attributes have been proposed to map permeability by using detailed analysis of the frequency content of reflected wavetrains. Some attributes are expected to show a relative increase of high-frequency content with increased permeability; other attributes assume the opposite. Actually, both these trends were observed. A possible explanation of these observations is here derived from an effective model of a permeable dual-porosity layer enclosed by impermeable rocks. For such a model, the reflected wavetrain can be regarded as a sum of three components, one of which is related to acoustic-impedance contrasts, another to extra compliance caused by P-wave-induced fluid flows between fractures and intergranular pores with a high aspect ratio, and a third to the fluid-flow-induced, inelastic attenuation. In layered reservoirs, all the components tend to be frequency dependent, and the well-known dependence of the first component on the reflecting-layer thickness may strongly dominate the effects of permeability. Hence, predicting the behavior of a permeability attribute in a particular environment requires a modeling formalism that can be called permeability substitution by analogy with the widely used fluid-substitution technique.
Atherosclerosis in ANCA‐Associated Vasculitides
Authors: PAGNOUX CHRISTIAN , CHIRONI GILLES , SIMON ALAIN , GUILLEVIN LOÏC
Published: September 2007

Abstract:  It is currently accepted that atherosclerosis is rather, or also, an inflammatory disease and, indeed, vasculitis is defined by inflammatory infiltrates in blood vessel walls, albeit initially by different predominant cell populations and in arteries of different calibers. As for other chronic systemic inflammatory diseases, premature and accelerated atherosclerosis has emerged during the last 5–10 years as an important facet of vasculitides, independently of the other risk factors of cardiovascular disease and also, apparently, corticosteroids. Chronic systemic inflammation, like persistently active vasculitis, might play a role in early atherosclerosis, through the actions of C‐reactive protein (CRP), some adhesion molecules, and/or cytokines, as well as local inflammation, perhaps through locally secreted TNF‐α and/or upregulation of matrix metalloproteinases and oxidative stress. Endothelial cell dysfunction and increased arterial stiffness have also been found in vasculitis patients. Notably, some vasculitis treatments were able to reverse some of these endothelial cell anomalies. Unlike antineutrophil cytoplasm autoantibodies (ANCA), which were not shown to correlate with a higher risk of atherosclerosis or cardiovascular events, autoantibodies to endothelial cells, heat‐shock proteins, or oxidized‐LDL may also be implicated, although these latter are now thought to protect against atherosclerosis. It is likely that other, as yet unidentified, factors facilitating atherosclerosis may play more important roles in vasculitides. Until their precise identification, it remains important to take into consideration and treat, every time it is necessary and possible, the other well‐known cardiovascular risk factors.
CD4‐Positive Effector Memory T Cells Participate in Disease Expression in ANCA‐Associated Vasculitis
Authors: ABDULAHAD WAYEL H. , STEGEMAN COEN A. , LIMBURG PIETER C. , KALLENBERG CEES G.M.
Published: September 2007

Abstract:  Although the cause of ANCA‐associated vasculitis (AAV) remains undetermined, the presence of lymphocytic infiltrates in inflammatory lesions of patients suggests that vascular damage is immune mediated. Studies over the past decade have implicated a role for T cells in the pathogenesis of AAV as altered T cell phenotype has been observed in this disorder. The distribution of T cell subpopulations has been analyzed most intensely in Wegener's granulomatosis (WG), where an expanded population of circulating CD4+ effector memory T cells (CD4+TEM) was demonstrated. CD4+TEM cells play a major role in the pathogenesis of several autoimmune diseases. Specific suppression of CD4+TEM cells inhibits delayed‐type hypersensitivity (DTH) and has therapeutic potential in autoimmune disease. Thus, CD4+TEM cells may act as inducers of tissue injury and participate in the development of AAV. Therapies that target CD4+TEM, without impairing the activity of other lymphocyte subsets, may hold therapeutic promise for AAV.
Surface Expression of Fractalkine Receptor (CX3CR1) on CD4+/CD28− T Cells in RA Patients and Correlation with Atherosclerotic Damage
Authors: PINGIOTTI ELISA , CIPRIANI PAOLA , MARRELLI ALESSANDRA , LIAKOULI VASILIKI , FRATINI SIMONA , PENCO MARIA , GIACOMELLI ROBERTO
Published: September 2007

Abstract:  Rheumatoid arthritis (RA) is associated with accelerated atherosclerosis. Fractalkine, a CX3C/chemokine (CX3CL1), mediates monocytes–macrophage infiltration in activated endothelium, suggesting its specific role in atherosclerosis‐related inflammation. In this study, we evaluate the following in early RA patients: the expression of fractalkine receptor (CX3CR1) on CD4+/CD28− T cells, a subset involved in atherosclerotic infiltration; the correlation between this subset and validated markers of early atherosclerosis. CD4+ T cells were isolated by immunomagnetics beads in 50 early RA patients and 26 healthy controls (HC). After isolation, CD4+/CD28−/CX3CR1+ T lymphocytes were assessed by FACS analysis. Endothelial dysfunction was evaluated by both carotid intima‐media thickness (IMT) and flow‐mediated vasodilation (FMV). We observed: a higher expansion of CD4+/CD28− subset in RA patients when compared to HC (7.7%, 5.15–9.7 vs. 0.7%, 0.2–1.5, P < 0.01; respectively); this expansion directly correlated with increased IMT (0.91 mm, 0.5–1.3 vs. 0.7 mm, 0.2–1, P < 0.01; RA vs. C, respectively) and inversely correlated with FMV (3.5%, 1.7–7 vs. 9%, 3.5–11, P < 0.01; RA vs. C, respectively); the large majority of CD4+/CD28−, in RA, coexpressed CX3CR1 (93%, 67–99 vs. 30%, 10–48, P < 0.01; RA vs. C, respectively); this expansion significantly correlated with both the parameters of premature vascular damage and DAS 28. Our data suggest that CX3CL1/CX3CR1 axis might play a role in the induction and development of the endothelial dysfunction during RA.
Migratory Pathways of γδ T Cells and Response to CXCR3 and CXCR4 Ligands
Authors: POGGI A. , ZANCOLLI M. , CATELLANI S. , BORSELLINO G. , BATTISTINI L. , ZOCCHI M.R.
Published: September 2007

Abstract:  Gammadelta T lymphocytes are thought to be involved in multiple sclerosis (MS) pathogenesis. In this work, we discuss the characteristics of these cells and possible implications in the pathogenesis of MS, focusing on the mechanism(s) underlying extravasation and tissue localization. Phenotype and transendothelial migration of γδ T cells from healthy donors and patients with relapsing–remitting MS were studied. In MS patients the Vδ2 T cell subset, expressing NKRP1A/CD161 adhesion molecule, is expanded and capable of transendothelial migration. Vδ1/Vδ2 subsets use distinct signal transduction pathways: Vδ1 cells lack NKRP1A and express PECAM‐1/CD31, which drives transmigration, while Vδ2 cells are PECAM‐1 negative and use NKRP1A. Vδ2 migration is coupled with CAMKII, whereas Vδ1 depend on PI‐3K. NKRP1A and PECAM‐1 selectively activate the two pathways: indeed, oligomerization of NKRP1A on Vδ2 T cells leads to CAMKII activation, occupancy of PECAM‐1 on Vδ1 cells triggers the PI‐3K‐dependent Akt/PKB pathway. Moreover, Vδ2 T cells are CXCR3brightCXCR4dull, while Vδ1 are mostly CXCR4+. Vδ1 and Vδ2 cells transmigrate in response to IP‐10/CXCL10 and SDF‐1/CXCL12 according to the expression of their specific receptors. In a fraction of Vδ1 T cells coexpressing CXCR3 and CXCR4, the homeostatic chemokine 6Ckine/SLC/CCL21 is more effective. IP‐10/CXCL10 or 6Ckine/SLC/CCL21 and SDF‐1/CXCL12‐induced transmigration is coupled to PI‐3K/Akt/PKB, but only CXCR3 is capable of inducing CAMKII activation. We suggest that both subsets of γδ T lymphocytes may migrate to the site of lesion in MS using two different signaling pathways to extravasate and responding to different chemokines.
Brain‐Specific Autoantibodies in the Plasma of Subjects with Autistic Spectrum Disorder
Authors: CABANLIT MARICEL , WILLS SHARIFIA , GOINES PAULA , ASHWOOD PAUL , VAN DE WATER JUDY
Published: September 2007

Abstract:  Although autism spectrum disorder (ASD) is diagnosed on the basis of behavioral parameters, several studies have reported immune system abnormalities and suggest the possible role of autoimmunity in the pathogenesis of ASD. In this study we sought to assess the incidence of brain‐specific autoantibodies in the plasma of children with autism (AU) compared to age‐matched controls including, siblings without ASD, typically developing (TD) controls, and children with other developmental disabilities, but not autism (DD). Plasma from 172 individuals (AU, n= 63, median age: 43 months; TD controls, n= 63, median age: 48 months; siblings, n= 25, median age: 61 months; and DD controls, n= 21, median age: 38 months) was analyzed by Western blot for the presence of IgG antibodies against protein extracts from specific regions of the human adult brain including the hypothalamus and thalamus. The presence of a ∼ 52 kDa MW band, in the plasma of subjects with AU, was detected with a significantly higher incidence when compared to plasma from TD controls (29% vs. 8%, P= 0.0027 and 30% vs. 11%, P= 0.01, in the thalamus and hypothalamus, respectively). Reactivity to three brain proteins (42–48 kDa MW), in particular in the hypothalamus, were observed with increased incidence in 37% of subjects with AU compared to 13% TD controls (P= 0.004). Multiple brain‐specific autoantibodies are present at significantly higher frequency in children with AU. While the potential role of these autoantibodies in AU is currently unknown, their presence suggests a loss of self‐tolerance to one or more neural antigens during early childhood.
DNA Microarray in Search of New Drug Targets for Myasthenia Gravis
Authors: FEFERMAN TALI , ARICHA REVITAL , MENON RENUKA , SOUROUJON MIRIAM C. , BERRIH‐AKNIN SONIA , FUCHS SARA
Published: September 2007

Abstract:  DNA microarray technology was used to identify new potential drug targets for myasthenia gravis (MG), to delineate genes involved in the pathogenesis of the disease and to possibly target their protein products for immunotherapy. In this study we compared the gene expression in lymph node cells (LNC) and muscles of rats with experimental autoimmune MG (EAMG) to those of control, healthy rats. Of the genes that were found to be deregulated in EAMG, we chose to elaborate on two gene systems: (a) The chemokine IFN‐γ‐inducible protein 10 (IP‐10, CXCL10), and its receptor (CXCR3) and (b) phosphodiesterases.
Cytokine Levels during Pregnancy Influence Immunological Profiles and Neurobehavioral Patterns of the Offspring
Authors: PONZIO NICHOLAS M. , SERVATIUS RICHARD , BECK KEVIN , MARZOUK ATARA , KREIDER TIM
Published: September 2007

Abstract:  The underlying causes of autism spectrum disorders (ASD) are unknown, but clinical and experimental studies indicate immune mechanisms, in general, and cytokine dysregulation, in particular, as contributing factors in their etiology. We developed a prenatal mouse model of autism to demonstrate that circulating levels of defined cytokines in pregnant dams could influence fetal development and behavioral characteristics in their offspring. We administered daily injections of murine IL‐2 (0.4 μg in phosphate‐buffered saline [PBS]) to pregnant mice during mid‐gestation, and analyzed their offspring (IL‐2 pups) in comparison to offspring of pregnant mice injected with vehicle only (PBS pups). Significant levels of IL‐2 were present in amniotic fluid and tissues from embryos of dams given radiolabeled IL‐2, indicating that the injected IL‐2 crossed the placenta and entered the fetuses. Lymphocytes from IL‐2 pups demonstrated accelerated T cell development, with a skewing toward TH1 cell differentiation. IL‐2 pups also showed in vitro proliferative and cytotoxicity responses that were significantly higher than control PBS pups when stimulated with syngeneic B lymphoma cells or allogeneic spleen cells. In addition to their previously shown increases in open‐field activity, grooming and rearing behavior, offspring of IL‐2‐injected (vs. PBS‐injected) dams also displayed abnormal new motor learning as assessed through acquisition of the classically conditioned eyeblink response. These results suggest that increases in maternal levels of IL‐2 during pregnancy induce in their offspring long‐lasting increased vulnerability to neurobehavioral abnormalities associated with autism, and provide a valid animal model to determine the underlying immunological mechanisms.
Autoimmunity in the Brain
Authors: JOVANOVA‐NESIC KATICA , SHOENFELD YEHUDA
Published: September 2007

Abstract:  The aim of the study is to explore the relationship between leakage of the blood‐brain barrier and inflammation, the reason why demyelination occurs—seemingly in the absence of an antigen‐specific immune response that requires explanation if a coherent account of an inflammatory‐mediated demyelination is to be achieved. In this study the cellular biology of the glial cells important for the synthesis and maintenance of central nervous system (CNS) myelin and their inter‐relations with other environmental cells (neuronal, microglial, olygodendroglial, astrocytes, endothelial, epithelial, T lymphocytes, B lymphocytes, monocytes, and macrophages) and with the compound of the extracellular matrix (ECM) during the development of an autoimmune inflammatory and demyelinating processes in the brain was analyzed. Upon activation in the peripheral tissue, immune cells reach their target organ via bloodstream and interacting with blood vessels wall components in the absence of exogenous stimulus mount an attack against the local milleu, which is the starting point of a pathogenic inflammatory reaction. Each of these contacts may trigger profuse secretion of cytokines, chemokines, and other soluble inflammatory mediators, which in the CNS by activating of local glial cells and by attracting and stimulating blood‐borne monocyte/macrophages can act directly on neural cells and will cause their demyelination.
Autoimmunity in Complex‐Regional Pain Syndrome
Authors: BLAES F. , TSCHERNATSCH M. , BRAEU M. E. , MATZ O. , SCHMITZ K. , NASCIMENTO D. , KAPS M. , BIRKLEIN F.
Published: September 2007

Abstract:  Complex regional pain syndrome (CRPS) is an etiologically unclear syndrome with the main symptoms being pain, trophic and autonomic disturbances, and functional impairment that develops after limb trauma or operation and is located at the distal site of the affected limb. Because autoantibodies against nervous system structures have been described in these patients, an autoimmune etiology of CRPS is discussed. These autoantibodies bind to the surface of peripheral autonomic neurons. Using a competitive binding assay, it can be shown that at least some of the CRPS sera bind to the same neuronal epitope. Autoimmune etiology of CRPS is a new pathophysiological concept and may have severe impact on the treatment of this often chronic disease.
Increased IL‐18 Production by Dendritic Cells in Active Inflammatory Myopathies
Authors: TUCCI MARCO , QUATRARO COSIMA , DAMMACCO FRANCO , SILVESTRIS FRANCO
Published: September 2007

Abstract:  Inflammatory myopathies (IM) are chronic disorders characterized by muscular accumulation of inflammatory cells that promote cytotoxicity and tissue damage. Overexpression of chemokines and cytokines as well as imbalance of dendritic cells (DC) homeostasis have been postulated to exert a role in both dermatomyositis (DM) and polymyositis (PM). We studied the T helper (Th)‐1 and Th2 cytokine levels by enzyme linked immunosorbent assay (ELISA) and the muscular expression of IL‐18 and its receptor by both histochemistry (HIC) and in situ hybridization (ISH) in both patients and normal controls. Also, the cell populations infiltrating the muscles were investigated. We present evidence that DM and PM are characterized by a predominant Th1 immune response with high production of both interferon (IFN)‐γ and interleukin (IL)‐18 in the presence of reduced levels of IL‐4 and IL‐6. IL‐18 was also demonstrated in muscles and produced by both macrophages and DC surrounding either perivascular and perimysium areas or endomysium. IL‐18R was highly expressed by T cells and DC as well as by endothelial cells (EC) and smooth muscle cells (SMC). High concentrations of serum and muscular IL‐18 suggest that deregulated IL‐18/IL‐18R pathway may be pathogenetic in IM and measurement of IL‐18 might be predictive of the disease activity.
Significance of Endogenous Augmentation of Antiganglioside IgM in Cancer Patients
Authors: RAVINDRANATH MEPUR H. , MUTHUGOUNDER SAKUNTHALA , HANNAH MAGHASI R. , MORTON DONALD L.
Published: September 2007

Abstract:  Gangliosides expressed by solid malignancies are shed into the circulation at a rate that varies with tumor stage, burden, and progression. Gangliosides have an immunosuppressive effect; thus an increase in the total ganglioside (TG) serum level may coincide with tumor progression. However, circulating gangliosides also may induce an endogenous IgM response. Unlike conventional pentameric IgM antibodies against peptide antigens, antiganglioside IgM antibodies can be polymeric and may not have a J‐chain. Because these antibodies can remove shed gangliosides from the tumor microenvironment and the circulation, therapy that actively or passively augments serum levels of IgM against tumor‐derived immunosuppressive gangliosides might restore immunocompetence and thereby slow tumor progression. The success of this approach, in passive and active specific therapy of cancer patients, requires analysis of biopsy tissue or sera of therapy recipients to confirm the presence of target gangliosides, such as GM2 or GD3. A patient's response to active or passive immunotherapy against a specific ganglioside target(s) can be monitored by serial assessment of serum specimens for TG level and antiganglioside IgM titer(s). This tailored approach to immunotherapy could be incorporated in postoperative adjuvant protocols.
Cancer Immunomics
Authors: HARDOUIN JULIE , LASSERRE JEAN‐PAUL , SYLVIUS LOÏK , JOUBERT‐CARON RAYMONDE , CARON MICHEL
Published: September 2007

Abstract:  Cancer remains one of the leading causes of death worldwide. Thus, to identify any useful biomarkers is still a need. We performed “cancer immunomics” to identify autoantibody signatures produced in response to the presence of either breast or colorectal cancer. SERological proteome analysis (SERPA) was performed by two‐dimensional (2‐D) electrophoresis separation, immunoblotting, image analysis, and mass spectrometry. Alternatively, to identify the antigens recognized by the autoantibodies of cancer patients, we developed an approach combining 2‐D immunoaffinity chromatography, enzymatic digestion of the isolated antigens, nano flow separation of the resulting peptides, and identification: MAPPing (multiple affinity protein profiling). By these approaches we identified both proteins recognized by autoantibodies independently of a cancer status, and a limited number of proteins reacting preferentially with cancer sera.
Paraneoplastic Pemphigus Associated with Castleman's Disease
Authors: ALARCÓN‐TORRES I. , BASTIDA‐IÑARREA J. , RODRÍGUEZ‐SALIDO M.J. , GÓMEZ‐DUASO J. , RUA‐FIGUEROA I. , GARCÍA‐AGUILAR G.D. , MARTÍN‐ALFARO R.
Published: September 2007

Abstract:  We report on a case of paraneoplastic pemphigus associated with Castleman's disease. Clinical pathologic features were not conclusive. Diagnosis was established thanks to the detection of seric autoantibodies directed against intercellular substance by indirect immunofluorescence on monkey esophagus. The positive result of this test prompted us to reevaluate the patient and to detect the occult neoplasia. The demonstration of autoantibodies against plakins is the key marker of this disease but depends on tests that may not be readily available in many places like immunoprecipitation, immunoblotting, or indirect immunofluorescence over rat bladder. In this setting, tests like indirect immunofluorescence over monkey esophagus, although unspecific, may aid in reaching the appropriate diagnosis. This case illustrates the importance of the laboratory of autoimmunity in the diagnosis of this type of pemphigus.
Interleukin‐2 Mastering Regulation in Cancer and Autoimmunity
Authors: MONTERO ENRIQUE , ALONSO LIVAN , PEREZ ROLANDO , LAGE AGUSTIN
Published: September 2007

Abstract:  Autoimmunity and tumor immunity evolved as two distinct arenas in immunological research. However, the identification of self‐antigens as the major components of malignant cells may define a central role for autoimmunity in cancer control tuned by peripheral immunoregulatory mechanisms avoiding self‐aggression. Emerging evidence documents a triple antagonistic role of interleukin‐2 (IL‐2) in vivo promoting survival, apoptosis, and the generation of regulatory T cells. We have found that IL‐2 administration reduces the clinical course of experimental autoimmune encephalomyelitis and enhances immunoregulation in tumor‐bearing mice. However, actively induced anti‐IL‐2 antibodies restore the response to nominal antigens in tumor‐induced immunosuppressed host and induced therapeutic effect in transplantable and chemically induced tumors. It is suggested that IL‐2 may contribute dynamically to the maintenance of natural immunological tolerance, preventing pathological autoimmunity, but may affect antitumor immunity. Cancer research has gained from autoimmunity understanding that tumor escape strategies include the natural mechanisms of immune tolerance and the ways to imbalance the peripheral regulatory mechanisms. Interestingly, therapeutic manipulations of immunoregulation have limited antitumor effects, although promoting collaterally infrequent autoimmune diseases. It may suggest that tumors may reinforce tolerance to protect themselves from the immune attack, a process that may involve dynamically various mechanisms including IL‐2. Understanding this acquired experience from tumors may help utilize them to revert the immunopathology in autoimmune diseases.