322 research outputs found
Disrupted Lipid Metabolism in Multiple Sclerosis: A Role for Liver X Receptors?
Multiple sclerosis (MS) is a chronic neurological disease driven by autoimmune, inflammatory and neurodegenerative processes leading to neuronal demyelination and subsequent degeneration. Systemic lipid metabolism is disturbed in people with MS, and lipid metabolic pathways are crucial to the protective process of remyelination. The lipid-activated transcription factors liver X receptors (LXRs) are important integrators of lipid metabolism and immunity. Consequently, there is a strong interest in targeting these receptors in a number of metabolic and inflammatory diseases, including MS. We have reviewed the evidence for involvement of LXR-driven lipid metabolism in the dysfunction of peripheral and brain-resident immune cells in MS, focusing on human studies, both the relapsing remitting and progressive phases of the disease are discussed. Finally, we discuss the therapeutic potential of modulating the activity of these receptors with existing pharmacological agents and highlight important areas of future research
Vapour-liquid coexistence in many-body dissipative particle dynamics
Many-body dissipative particle dynamics is constructed to exhibit
vapour-liquid coexistence, with a sharp interface, and a vapour phase of
vanishingly small density. In this form, the model is an unusual example of a
soft-sphere liquid with a potential energy built out of local-density dependent
one-particle self energies. The application to fluid mechanics problems
involving free surfaces is illustrated by simulation of a pendant drop.Comment: 8 pages, 6 figures, revtex
Diffusive transport of light in two-dimensional granular materials
We study photon diffusion in a two-dimensional random packing of monodisperse
disks as a simple model of granular material. We apply ray optics approximation
to set up a persistent random walk for the photons. We employ Fresnel's
intensity reflectance with its rich dependence on the incidence angle and
polarization state of the light. We present an analytic expression for the
transport-mean-free path in terms of the refractive indices of grains and host
medium, grain radius, and packing fraction. We perform numerical simulations to
examine our analytical result.Comment: 9 pages, 3 figure
Hydrodynamic bubble coarsening in off-critical vapour-liquid phase separation
Late-stage coarsening in off-critical vapour-liquid phase separation is
re-examined. In the limit of bubbles of vapour distributed throughout a
continuous liquid phase, it is argued that coarsening proceeds via inertial
hydrodynamic bubble collapse. This replaces the Lifshitz-Slyozov-Wagner
mechanism seen in binary liquid mixtures. The arguments are strongly supported
by simulations in two dimensions using a novel single-component soft sphere
fluid.Comment: 5 pages, 3 figures, revtex3.
3D Spinodal Decomposition in the Inertial Regime
We simulate late-stage coarsening of a 3D symmetric binary fluid using a
lattice Boltzmann method. With reduced lengths and times l and t respectively
(scales set by viscosity, density and surface tension) our data sets cover 1 <
l
100 we find clear evidence of Furukawa's inertial scaling (l ~ t^{2/3}),
although the crossover from the viscous regime (l ~ t) is very broad. Though it
cannot be ruled out, we find no indication that Re is self-limiting (l ~
t^{1/2}) as proposed by M. Grant and K. R. Elder [Phys. Rev. Lett. 82, 14
(1999)].Comment: 4 pages, 3 eps figures, RevTex, minor changes to bring in line with
published version. Mobility values added to Table
Persistence exponents in a 3D symmetric binary fluid mixture
The persistence exponent, theta, is defined by N_F sim t^theta, where t is
the time since the start of the coarsening process and the "no-flip fraction",
N_F, is the number of points that have not seen a change of "color" since t=0.
Here we investigate numerically the persistence exponent for a binary fluid
system where the coarsening is dominated by hydrodynamic transport. We find
that N_F follows a power law decay (as opposed to exponential) with the value
of theta somewhat dependent on the domain growth rate (L sim t^alpha, where L
is the average domain size), in the range theta=1.23 +-0.1 (alpha = 2/3) to
theta=1.37 +-0.2 (alpha=1). These alpha values correspond to the inertial and
viscous hydrodynamic regimes respectively.Comment: 9 pages RevTex, 9 figures included as eps files on last 3 pages,
submitted to Phys Rev
Tests of Dynamical Scaling in 3-D Spinodal Decomposition
We simulate late-stage coarsening of a 3-D symmetric binary fluid. With
reduced units l,t (with scales set by viscosity, density and surface tension)
our data extends two decades in t beyond earlier work. Across at least four
decades, our own and others' individual datasets (< 1 decade each) show viscous
hydrodynamic scaling (l ~ a + b t), but b is not constant between runs as this
scaling demands. This betrays either the unexpected intrusion of a
discretization (or molecular) lengthscale, or an exceptionally slow crossover
between viscous and inertial regimes.Comment: Submitted to Phys. Rev.
Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction
A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and
width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state
is consistent with a number of broad resonances predicted by recent cluster
model calculations. The well-established reaction mechanism, combined with a
simple and transparent analysis procedure confers considerable validity to this
observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication
in Phys. Rev. C, August, 200
Using serum metabolomics analysis to predict sub-clinical atherosclerosis in patients with SLE
Background: Patients with systemic lupus erythematosus (SLE) have an increased risk of developing cardiovascular disease (CVD) and 30-40% have sub-clinical atherosclerosis on vascular ultrasound scanning. Standard measurements of serum lipids in clinical practice do not predict CVD risk in patients with SLE. We hypothesise that more detailed analysis of lipoprotein taxonomy could identify better predictors of CVD risk in SLE. /
Methods: Eighty patients with SLE and no history of CVD underwent carotid and femoral ultrasound scans; 30 had atherosclerosis plaques (SLE-P) and 50 had no plaques (SLE-NP). Serum samples obtained at the time of the scan were analysed using a lipoprotein-focused metabolomics platform assessing 228 metabolites by nuclear magnetic resonance spectroscopy. Data was analysed using logistic regression and five binary classification models with 10-fold cross validation; decision tree, random forest, support vector machine and lasso (Least Absolute Shrinkage and Selection Operator) logistic regression with and without interactions. /
Results: Univariate logistic regression identified four metabolites associated with the presence of sub-clinical plaque; three subclasses of very low density lipoprotein (VLDL) (percentage of free cholesterol in medium and large VLDL particles and percentage of phospholipids in chylomicrons and extremely large VLDL particles) and Leucine. Together with age, these metabolites were also within the top features identified by the lasso logistic regression (with and without interactions) and random forest machine learning models. Logistic regression with interactions differentiated between SLE-P and SLE-NP with greatest accuracy (0.800). Notably, percentage of free cholesterol in large VLDL particles and age were identified by all models as being important to differentiate between SLE-P and SLE-NP patients. /
Conclusion: Serum metabolites are a promising biomarker for prediction of sub-clinical atherosclerosis development in SLE patients and could provide novel insight into mechanisms of early atherosclerosis development
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