bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence that Dkk‐1 is dysfunctional in ankylosing spondylitis
Authors: Daoussis Dimitrios , Liossis Stamatis‐Nick C. , Solomou Elena E. , Tsanaktsi Anastasia , Bounia Konstadina , Karampetsou Maria , Yiannopoulos Georgios , Andonopoulos Andrew P. 
Published: December 2009

AbstractObjectiveDkk‐1 is an inhibitory molecule that regulates the Wnt pathway, which controls osteoblastogenesis. This study was undertaken to explore the potential role of Dkk‐1 in ankylosing spondylitis (AS), a prototypical bone‐forming disease.MethodsSerum Dkk‐1 levels were measured in 45 patients with AS, 45 patients with rheumatoid arthritis (RA), 15 patients with psoriatic arthritis (PsA), and 50 healthy subjects by sandwich enzyme‐linked immunosorbent assay (ELISA). A functional ELISA was used to assess the binding of Dkk‐1 to its receptor (low‐density lipoprotein receptor–related protein 6). Furthermore, we studied the effect of sera from patients with AS and healthy subjects on the activity of the Wnt pathway in the Jurkat T cell model, with and without a neutralizing anti–Dkk‐1 monoclonal antibody, by Western immunoblotting.ResultsSerum Dkk‐1 levels were significantly increased in patients with AS (mean ± SEM 2,730 ± 135.1 pg/ml) as compared with normal subjects (P = 0.040), patients with RA (P = 0.020), and patients with PsA (P = 0.049). Patients with AS receiving anti–tumor necrosis factor α (anti‐TNFα) treatment had significantly higher serum Dkk‐1 levels than patients with AS not receiving such treatment (P = 0.007). Patients with AS studied serially prior to and following anti‐TNFα administration exhibited a significant increase in serum Dkk‐1 levels (P = 0.020), in contrast to patients with RA, who exhibited a dramatic decrease (P < 0.001). Jurkat cells treated with serum from AS patients exhibited increased Wnt signaling compared with cells treated with control serum. In that system, Dkk‐1 blockade significantly enhanced Wnt signaling in control serum–treated, but not AS serum–treated, Jurkat T cells.ConclusionOur findings indicate that in patients with AS, circulating bone formation–promoting factors functionally prevail. This can be at least partially attributed to decreased Dkk‐1–mediated inhibition.
Lack of effect of a single injection of human C‐reactive protein on murine lupus or nephrotoxic nephritis
Authors: Carlucci Francesco , Terence Cook H. , Garg Abhilok , Pepys Mark B. , Botto Marina 
Published: December 2009

AbstractObjectiveIt has been reported that a single dose of human C‐reactive protein (CRP) can prevent and reverse the renal damage in murine models of spontaneous lupus, as well as the rapid‐onset immune complex disease induced in the accelerated nephrotoxic nephritis (ANTN) model. This study was undertaken to attempt to replicate these observations using a highly purified and fully characterized human CRP preparation.Methods(NZB × NZW)F1 (NZB/NZW) mice were treated with a single 200‐μg subcutaneous injection of CRP or control reagents either before disease onset at 4 months of age or when high‐grade proteinuria was present at 7 months of age. Mice were monitored at least monthly for proteinuria and autoantibody levels. ANTN was induced by preimmunizing C57BL/6 mice with sheep IgG, followed 5 days later by injection of sheep anti‐mouse glomerular basement membrane antibody and CRP or control reagents. Renal disease was assessed by regular urinalysis and histologic evaluation.ResultsCRP treatment of NZB/NZW mice, either early or late in the disease, had no effect on proteinuria, autoantibody titers, or survival. CRP administration did not reduce renal injury or alter disease in the ANTN model. Human serum amyloid P component, a pentraxin protein that is very closely related to CRP, similarly had no effect.ConclusionOur completely negative observations do not confirm that human CRP has reproducible antiinflammatory or immunomodulatory effects in these murine models, nor do they support the suggestion that CRP might be useful for therapy of lupus or immune complex–mediated nephritis.
Efficacy and safety of rituximab in moderately‐to‐severely active systemic lupus erythematosus: The randomized, double‐blind, phase ii/iii systemic lupus erythematosus evaluation of rituximab trial
Authors: Merrill Joan T. , Neuwelt C. Michael , Wallace Daniel J. , Shanahan Joseph C. , Latinis Kevin M. , Oates James C. , Utset Tammy O. , Gordon Caroline , Isenberg David A. , Hsieh Hsin‐Ju , Zhang David , Brunetta Paul G. 
Published: December 2009

AbstractObjectiveB cells are likely to contribute to the pathogenesis of systemic lupus erythematosus (SLE), and rituximab induces depletion of B cells. The Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial tested the efficacy and safety of rituximab versus placebo in patients with moderately‐to‐severely active extrarenal SLE.MethodsPatients entered with ≥1 British Isles Lupus Assessment Group (BILAG) A score or ≥2 BILAG B scores despite background immunosuppressant therapy, which was continued during the trial. Prednisone was added and subsequently tapered. Patients were randomized at a ratio of 2:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182.ResultsIn the intent‐to‐treat analysis of 257 patients, background treatment was evenly distributed among azathioprine, mycophenolate mofetil, and methotrexate. Fifty‐three percent of the patients had ≥1 BILAG A score at entry, and 57% of the patients were categorized as being steroid dependent. No differences were observed between placebo and rituximab in the primary and secondary efficacy end points, including the BILAG‐defined response, in terms of both area under the curve and landmark analyses. A beneficial effect of rituximab on the primary end point was observed in the African American and Hispanic subgroups. Safety and tolerability were similar in patients receiving placebo and those receiving rituximab.ConclusionThe EXPLORER trial enrolled patients with moderately‐to‐severely active SLE and used aggressive background treatment and sensitive cutoffs for nonresponse. No differences were noted between placebo and rituximab in the primary and secondary end points. Further evaluation of patient subsets, biomarkers, and exploratory outcome models may improve the design of future SLE clinical trials.
Anti–neuropilin‐1 peptide inhibition of synoviocyte survival, angiogenesis, and experimental arthritis
Authors: Kong Jin‐Sun , Yoo Seung‐Ah , Kim Jung‐Wook , Yang Seung‐Pil , Chae Chi‐Bom , Tarallo Valeria , Falco Sandro De , Ryu Sung‐Ho , Cho Chul‐Soo , Kim Wan‐Uk 
Published: December 2009

AbstractObjectiveTo delineate the role of neuropilin‐1 (NP‐1), a vascular endothelial growth factor receptor (VEGFR), in rheumatoid inflammation and to determine whether blockade of NP‐1 could suppress synoviocyte survival and angiogenesis.MethodsVEGF111–165 peptide, which encompasses the NP‐1 binding domain of VEGF165, was generated by cleaving VEGF165 with plasmin. The effect of this peptide on the interaction between VEGF165 and its receptor was determined by 125I‐VEGFR binding assay. Assays to determine synoviocyte apoptosis, adhesion, and migration were performed in the presence of VEGF165 and/or the peptide. VEGF165‐induced angiogenesis was assessed by measuring the proliferation, tube formation, and wounding migration of endothelial cells (ECs). Mice were immunized with type II collagen to induce experimental arthritis.ResultsVEGF111–165 peptide specifically inhibited the binding of 125I‐VEGF165 to NP‐1 on rheumatoid synoviocytes and ECs. The peptide eliminated the VEGF165‐mediated increase in synoviocyte survival and activation of p‐ERK and Bcl‐2. The peptide also completely inhibited a VEGF165‐induced increase in synoviocyte adhesion and migration. In addition, the anti–NP‐1 peptide blocked VEGF165‐stimulated proliferation, capillary tube formation, and wounding migration of ECs in vitro. VEGF165‐induced neovascularization in a Matrigel plug in mice was also blocked by treatment with the peptide. Finally, subcutaneous injection of anti–NP‐1 peptide suppressed arthritis severity and autoantibody formation in mice with experimental arthritis and inhibited synoviocyte hyperplasia and angiogenesis in arthritic joints.ConclusionAnti–NP‐1 peptide suppressed VEGF165‐induced increases in synoviocyte survival and angiogenesis, and thereby blocked experimental arthritis. Our findings suggest that anti–NP‐1 peptide could be useful in alleviating chronic arthritis.
Tayler instability of toroidal magnetic fields in MHD Taylor‐Couette flows
Authors: Rüdiger G. , Schultz M. 
Published: December 2009

AbstractThe nonaxisymmetric Tayler instability (TI) of toroidal magnetic fields due to axial electric currents is studied for conducting incompressible fluids between two infinitely long corotating cylinders. For given Reynolds number of rotation the magnetic Prandtl number Pm of the liquid conductor and the ratio of the cylinder's rotation rates are the free parameters. It is shown that for resting cylinders the critical Hartmann number for instability does not depend on Pm hence the TI also exists in the limit Pm → 0. By rigid rotation the instability is suppressed where for Pm = 1 the rotational quenching takes its maximum. Rotation laws with negative shear (i.e. dΩ /dR < 0) strongly destabilize the toroidal field if the rotation is not too fast. In galaxies with their quadrupolar magnetic field geometry this effect could have drastic implications. For sufficiently high Reynolds numbers of rotation, however, the TI completely disappears. For the considered magnetic constellation the superrotation laws support the rotational stabilization. The angular momentum transport of the instability is anticorrelated with the shear so that an eddy viscosity can be defined which proves to be positive.We have also shown the possibility of laboratory TI experiments with a wide‐gap container filled with fluid metals like sodium or gallium. Even the effect of the rotational stabilization can be reproduced in the laboratory with electric currents of only a few kA (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of the solar magnetic field from SOHO/MDI
Authors: Benevolenskaya E.E. 
Published: December 2009

AbstractThe investigation of the dynamics of magnetic fields from small scales to the large scales is very important for the understanding of the nature of solar activity. It is also the base for producing adequate models of the solar cycle with the purpose to predict the level of solar activity. Since December 1995 the Michelson Doppler Imager (MDI) on board of the Solar and Heliospheric Observatory (SOHO) provides full disk magnetograms and synoptic maps which cover the period of solar cycle 23 and the current minimum. In this paper, I review the following important topics with a focus on the dynamics of the solar magnetic field. The synoptic structure of the solar cycle; the birth of the solar cycle (overlapping cycles 23 and 24); the relationship of the photospheric magnetic activity and the EUV solar corona, polar magnetic fields and dynamo theory (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Convective dynamos in spherical wedge geometry
Authors: Käpylä P.J. , Korpi M.J. , Brandenburg A. , Mitra D. , Tavakol R. 
Published: December 2009

AbstractSelf‐consistent convective dynamo simulations in wedge‐shaped spherical shells are presented. Differential rotation is generated by the interaction of convection with rotation. Equatorward acceleration and dynamo action are obtained only for sufficiently rapid rotation. The angular velocity tends to be constant along cylinders. Oscillatory large‐scale fields are found to migrate in the poleward direction. Comparison with earlier simulations in full spherical shells and Cartesian domains is made (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The interstellar magnetic field near the Galactic center
Authors: Ferrière K. 
Published: December 2009

AbstractWe review the current observational knowledge of the interstellar magnetic field within ∼150 pc ofthe Galactic center. We also discuss the various theoretical scenarios that have been put forward to explain the existing observations. Our critical overview leads to two important conclusions: (1) The interstellar magnetic field near the GC is approximately poloidal on average in the diffuse intercloud medium and approximately horizontal in dense interstellar clouds. (2) In the general intercloud medium, the field is relatively weak and probably close to equipartition with cosmic rays (B ∼ (6–20) μ G), but there exist a number of localized filaments where the field is much stronger (some filaments could possibly have B ≳ 1 mG). In dense interstellar clouds, the field is probably rather strong, with typical values ranging between a few 0.1 mG and a few mG (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of Ohmic diffusion on the excitation and dynamics of MRI
Authors: Korpi M.J. , Käpylä P.J. , Väisälä M.S. 
Published: December 2009

AbstractIn this paper we make an effort to understand the interaction of turbulence generated by the magnetorotational instability (MRI) with turbulence from other sources, such as supernova explosions (SNe) in galactic disks. First we perform a linear stability analysis (LSA) of non‐ideal MRI to derive the limiting value of Ohmic diffusion that is needed to inhibit the growth of the instability for different types of rotation laws. With the help of a simple analytical expression derived under first‐order smoothing approximation (FOSA), an estimate of the limiting turbulence level and hence the turbulent diffusion needed to damp the MRI is derived. Secondly, we perform numerical simulations in local cubes of isothermal nonstratified gas with external forcing of varying strength to see whether the linear result holds for more complex systems. Purely hydrodynamic calculations with forcing, rotation and shear are made for reference purposes, and as expected, non‐zero Reynolds stresses are found. In the magnetohydrodynamic calculations, therefore, the total stresses generated are a sum of the forcing and MRI contributions. To separate these contributions, we perform reference runs with MRI‐stable shear profiles (angular velocity increasing outwards), which suggest that the MRI‐generated stresses indeed become strongly suppressed as function of the forcing. The Maxwell to Reynolds stress ratio is observed to decrease by an order of magnitude as the turbulence level due to external forcing exceeds the predicted limiting value, which we interpret as a sign of MRI suppression. Finally, we apply these results to estimate the limiting radius inside of which the SN activity can suppress the MRI, arriving at a value of 14 kpc (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The origin of our galactic magnetic field
Authors: Kulsrud R.M. 
Published: December 2009

AbstractA serious difficulty with the standard alpha‐omega theory of the origin of galactic magnetic fields involves the question of flux expulsion. This is intimately related to flux freezing. The alpha‐omega theory is shown in the context of the giant superbubble explosions that have a large impact on the physics of the interstellar medium. It is shown that superbubbles alone can duplicate the processes of the alpha‐omega dynamo and produce exponential growth of the galactic magnetic field. The possibility of the blow‐out of pieces of the magnetic field is discussed and it is shown that they have the potential to solve the flux‐expulsion problem. However, such an explanation must lead to apparent ‘gaps’ in the field in the galactic disc. These gaps are probably unavoidable in any dynamo theory and should have important observable consequences, one of which is an explanation for the escape of cosmic rays from the disc (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fluctuation dynamo based on magnetic reconnections
Authors: Baggaley A.W. , Shukurov A. , Barenghi C.F. , Subramanian K. 
Published: December 2009

AbstractWe develop a new model of the fluctuation dynamo in which the magnetic field is confined to thin flux ropes advected by a multi‐scale flow which models turbulence. Magnetic dissipation occurs only via reconnections of flux ropes. The model is particularly suitable for rarefied plasma, such as the solar corona or galactic halos. We investigate the kinetic energy release into heat, mediated by dynamo action, both in our model and by solving the induction equation with the same flow. We find that the flux rope dynamo is more than an order of magnitude more efficient at converting mechanical energy into heat. The probability density of the magnetic energy released during reconnections has a power‐law form with the slope –3, consistent with the solar corona heating by nanoflares. We also present a nonlinear extension of the model. This shows that a plausible saturation mechanism of the fluctuation dynamo is the suppression of turbulent magnetic diffusivity, due to suppression of random stretching at the location of the flux ropes. We confirm that the probability distribution function of the magnetic line curvature has a power‐law form suggested by Schekochihin et al. (2002c). We argue, however, using our results that this does not imply a persistent folded structure of magnetic field, at least in the nonlinear stage (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The solar dynamo in the light of the distribution of various sunspot magnetic classes over butterfly diagram
Authors: Sokoloff D. , Khlystova A.I. 
Published: December 2009

AbstractWe present the data concerning the distribution of various sunspot magnetic classes over the solar butterfly diagram and discuss how this data can inform solar dynamo models. We use the statistics of sunspots that violate the Hale polarity law to estimate the ratio of the fluctuating and mean components of the toroidal magnetic field inside the solar convective zone. An analysis of the spatial distribution of bipolar, unipolar and complex sunspot groups in the context of simple dynamo models results in the conclusion that the mean toroidal field is relatively simple and maintains its shape during the course of the solar cycle (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparisons and connections between mean field dynamo theory and accretion disc theory
Authors: Blackman E.G. 
Published: December 2009

AbstractThe origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi‐analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha‐viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha‐accretion theory despite complementary weaknesses. In the 21st century however, MFDT has experienced a breakthrough with a dynamical saturation theory that consistently agrees with simulations. Such has not yet occurred in accretion disc theory, though progress is emerging. Ironically however, for accretion engines, MFDT and accretion theory are presently two artificially uncoupled pieces of what should be a single coupled theory. Large scale fields and accretion flows are dynamically intertwined because large scale fields likely play a key role in angular momentum transport. I discuss and synthesize aspects of recent progress in MFDT and accretion disc theory to suggest why the two likely conspire in a unified theory (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetohydrodynamic turbulence in a strongly magnetised plasma
Authors: Sridhar S. 
Published: December 2009

AbstractI present a review of incompressible magnetohydrodynamic (MHD) turbulence in a strongly magnetised plasma. The approach is phenomenological even where a more rigorous theory is available, so that a reader armed with paper, pencil and some determination may be able to work through most of the physics. The focus is on the inertial‐range spectra for very large (fluid and magnetic) Reynolds numbers. These theories of the inertial‐range are built on two important facts: (i) Kraichnan's insight that the turbulent cascades are a result of nonlinear interactions between oppositely directed wavepackets of Elsasser fields; (ii) these oppositely directed wavepackets do not exchange energy, but contribute only to changing each other's spatial structures. I begin with a description and critique of the Iroshnikov‐Kraichnan theory, and explore the fundamental departures necessitated by the anisotropic nature of the turbulence. Derivations of the inertial‐range spectra of four regimes of MHD turbulence – the balanced weak, balanced strong, imbalanced weak and the imbalanced strong cascades – are then presented. The need for studying the spectra of imbalanced turbulence when the waves on the outer scale have a short correlation time is briefly discussed (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Equatorial magnetic helicity flux in simulations with different gauges
Authors: Mitra D. , Candelaresi S. , Chatterjee P. , Tavakol R. , Brandenburg A. 
Published: December 2009

AbstractWe use direct numerical simulations of forced MHD turbulence with a forcing function that produces two different signs of kinetic helicity in the upper and lower parts of the domain. We show that the mean flux of magnetic helicity from the small‐scale field between the two parts of the domain can be described by a Fickian diffusion law with a diffusion coefficient that is approximately independent of the magnetic Reynolds number and about one third of the estimated turbulent magnetic diffusivity. The data suggest that the turbulent diffusive magnetic helicity flux can only be expected to alleviate catastrophic quenching at Reynolds numbers of more than several thousands. We further calculate the magnetic helicity density and its flux in the domain for three different gauges. We consider the Weyl gauge, in which the electrostatic potential vanishes, the pseudo‐Lorenz gauge, where the speed of light is replaced by the sound speed, and the ‘resistive gauge’ in which the Laplacian of the magnetic vector potential acts as a resistive term. We find that, in the statistically steady state, the time‐averaged magnetic helicity density and the magnetic helicity flux are the same in all three gauges (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simple laminar dynamos
Authors: Moss D. 
Published: December 2009

AbstractAlthough current interest in astrophysical dynamo theory is largely focussed on flows with both large‐ and small‐scale motions, historically the study of dynamos driven by laminar flows has been important. Some classical laminar flow dynamos are reviewed. These results were obtained in an asymptotic regime corresponding to small values of system parameters. Numerical simulations have since been used to extend these results outside of these asymptotic regimes; the asymptotic results remain useful approximations well outside of their formal regions of validity. By changing slightly the system geometries some interesting new results have recently been obtained The latter include the very simple “one‐roll” dynamo, with motions in a single meridional cell contained within a spherical volume of fluid, without differential rotation (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)