705 research outputs found
The role of interleukin 12 and nitric oxide in the development of spontaneous autoimmune disease in MRL/MP-lpr/lpr mice
MRL/MP-lpr/lpr (MRL/lpr) mice develop a spontaneous autoimmune disease. Serum from these mice contained significantly higher concentrations of nitrite/nitrate than serum from age-matched control MRL/MP-+/+ (MRL/+), BALB/c or CBA/6J mice. Spleen and peritoneal cells from MRL/lpr mice also produced significantly more nitric oxide (NO) than those from the control mice when cultured with interferon (IFN) gamma and lipopolysaccharide (LPS) in vitro. It is interesting to note that peritoneal cells from MRL/lpr mice also produced markedly higher concentrations of interleukin (IL) 12 than those from MRL/+ or BALB/c mice when cultured with same stimuli. It is striking that cells from MRL/lpr mice produced high concentrations of NO when cultured cells from MRL/+ or BALB/c mice. The enhanced NO synthesis induced by IFN- gamma/LPS was substantially inhibited by anti-IL-12 antibody. In addition, IL-12-induced NO production can also be markedly inhibited by anti-IFN-gamma antibody, but only weakly inhibited by anti-tumor necrosis factor alpha antibody. The effect of IL-12 on NO production was dependent on the presence of natural killer and possibly T cells. Serum from MRL/lpr mice contained significantly higher concentrations of IL-12 compared with those of MRL/+ or BALB/c control mice. Daily injection of recombinant IL-12 led to increased serum levels of IFN- gamma and NO metabolites, and accelerated glomerulonephritis in the young MRL/lpr mice (but not in the MRL/+ mice) compared with controls injected with phosphate-buffered saline alone. These data, together with previous finding that NO synthase inhibitors can ameliorate autoimmune disease in MRL/lpr mice, suggest that high capacity of such mice to produce IL-12 and their greater responsiveness to IL-12, leading to the production of high concentrations of NO, are important factors in this spontaneous model of autoimmune disease
Antibacterial effect of orange Monascus pigment against Staphylococcus aureus
The objective of this work was to research the antibacterial effects of orange pigment, which was separated from Monascus pigments, against Staphylococcus aureus. The increase of the diameter of inhibition zone treated with orange pigment indicated that orange pigment had remarkable antibacterial activities against S. aureus. Orange pigment (10 mg mlâ1) had a strong destructive effect on the membrane and structure of S. aureus by the analysis of scanning electron microscopy as well as transmission electron microscopy. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) further demonstrated that the cell membrane was seriously damaged by orange pigment, which resulted in the leakage of protein from S. aureus cells. A significant decrease in the synthesis of DNA was also seen in S. aureus cells exposed to 10 mg mlâ1 orange pigment. All in all, orange pigment showed excellent antibacterial effects against S. aureus
The Electron Spectral Function in Two-Dimensional Fractionalized Phases
We study the electron spectral function of various zero-temperature
spin-charge separated phases in two dimensions. In these phases, the electron
is not a fundamental excitation of the system, but rather ``decays'' into a
spin-1/2 chargeless fermion (the spinon) and a spinless charge e boson (the
chargon). Using low-energy effective theories for the spinons (d-wave pairing
plus possible N\'{e}el order), and the chargons (condensed or quantum
disordered bosons), we explore three phases of possible relevance to the
cuprate superconductors: 1) AF*, a fractionalized antiferromagnet where the
spinons are paired into a state with long-ranged N\'{e}el order and the
chargons are 1/2-filled and (Mott) insulating, 2) the nodal liquid, a
fractionalized insulator where the spinons are d-wave paired and the chargons
are uncondensed, and 3) the d-wave superconductor, where the chargons are
condensed and the spinons retain a d-wave gap. Working within the gauge
theory of such fractionalized phases, our results should be valid at scales
below the vison gap. However, on a phenomenological level, our results should
apply to any spin-charge separated system where the excitations have these
low-energy effective forms. Comparison with ARPES data in the undoped,
pseudogapped, and superconducting regions is made.Comment: 10 page
Bridging the gap between stellar-mass black holes and ultraluminous X-ray sources
The X-ray spectral and timing properties of ultraluminous X-ray sources
(ULXs) have many similarities with the very high state of stellar-mass black
holes (power-law dominated, at accretion rates greater than the Eddington
rate). On the other hand, their cool disk components, large characteristic
inner-disk radii and low characteristic timescales have been interpreted as
evidence of black hole masses ~ 1000 Msun (intermediate-mass black holes). Here
we re-examine the physical interpretation of the cool disk model, in the
context of accretion states of stellar-mass black holes. In particular, XTE
J1550-564 can be considered the missing link between ULXs and stellar-mass
black holes, because it exhibits a high-accretion-rate, low-disk-temperature
state (ultraluminous branch). On the ultraluminous branch, the accretion rate
is positively correlated with the disk truncation radius and the bolometric
disk luminosity, while it is anti-correlated with the peak temperature and the
frequency of quasi-periodic-oscillations. Two prototypical ULXs (NGC1313 X-1
and X-2) also seem to move along that branch. We use a phenomenological model
to show how the different range of spectral and timing parameters found in the
two classes of accreting black holes depends on both their masses and accretion
rates. We suggest that ULXs are consistent with black hole masses ~ 50-100
Msun, moderately inefficiently accreting at ~20 times Eddington.Comment: 11 pages, accepted for publication in Astrophysics and Space Science.
Based on work presented at the Fifth Stromlo Symposium, Australian National
University, Dec 200
Disease map-based biomarker selection and pre-validation for bladder cancer diagnostic
YesContext: Urinary biomarkers are promising as simple alternatives to cystoscopy for the diagnosis of de novo and recurrent bladder cancer.
Objective: To identify a highly sensitive and specific biomarker candidate set with potential clinical utility in bladder cancer.
Materials and methods: Urinary biomarkers concentrations were determined by ELISA. The performance of individual markers and marker combinations was assessed using ROC analysis.
Results: A 5-biomarker panel (IL8, MMP9, VEGFA, PTGS2 and EN2) was defined from the candidate set.
Discussion and conclusion: This panel showed a better overall performance than the best individual marker. Further validation studies are needed to evaluate its clinical utility in bladder cancer.This work has been supported in part by the European Commission Program DIPROMON - HEALTH-F5-2012-306157-2: Development of an integrated protein- and cell-based device for non-invasive diagnostics in the urogenital tract
DCC Dynamics in (2+1)D-O(3) model
The dynamics of symmetry-breaking after a quench is numerically simulated on
a lattice for the (2+1)-dimensional O(3) model. In addition to the standard
sigma-model with temperature-dependent Phi^4-potential the energy functional
includes a four-derivative current-current coupling to stabilize the size of
the emerging extended topological textures. The total winding number can be
conserved by constraint. As a model for the chiral phase transition during the
cooling phase after a hadronic collision this allows to investigate the
interference of 'baryon-antibaryon' production with the developing disoriented
aligned domains. The growth of angular correlations, condensate, average
orientation is studied in dependence of texture size, quench rate, symmetry
breaking. The classical dissipative dynamics determines the rate of energy
emitted from the relaxing source for each component of the 3-vector field which
provides a possible signature for domains of Disoriented Chiral Condensate. We
find that the 'pions' are emitted in two distinct pulses; for sufficiently
small lattice size the second one carries the DCC signal, but it is strongly
suppressed as compared to simultaneous 'sigma'-meson emission. We compare the
resulting anomalies in the distributions of DCC pions with probabilities
derived within the commonly used coherent state formalism.Comment: 27 pages, 17 figures; several minor insertions in the text; two
references adde
Black Holes from Cosmic Rays: Probes of Extra Dimensions and New Limits on TeV-Scale Gravity
If extra spacetime dimensions and low-scale gravity exist, black holes will
be produced in observable collisions of elementary particles. For the next
several years, ultra-high energy cosmic rays provide the most promising window
on this phenomenon. In particular, cosmic neutrinos can produce black holes
deep in the Earth's atmosphere, leading to quasi-horizontal giant air showers.
We determine the sensitivity of cosmic ray detectors to black hole production
and compare the results to other probes of extra dimensions. With n \ge 4 extra
dimensions, current bounds on deeply penetrating showers from AGASA already
provide the most stringent bound on low-scale gravity, requiring a fundamental
Planck scale M_D > 1.3 - 1.8 TeV. The Auger Observatory will probe M_D as large
as 4 TeV and may observe on the order of a hundred black holes in 5 years. We
also consider the implications of angular momentum and possible exponentially
suppressed parton cross sections; including these effects, large black hole
rates are still possible. Finally, we demonstrate that even if only a few black
hole events are observed, a standard model interpretation may be excluded by
comparison with Earth-skimming neutrino rates.Comment: 30 pages, 18 figures; v2: discussion of gravitational infall, AGASA
and Fly's Eye comparison added; v3: Earth-skimming results modified and
strengthened, published versio
Electronic localization at mesoscopic length scales: different definitions of localization and contact effects in a heuristic DNA model
In this work we investigate the electronic transport along model DNA
molecules using an effective tight-binding approach that includes the backbone
on site energies. The localization length and participation number are examined
as a function of system size, energy dependence, and the contact coupling
between the leads and the DNA molecule. On one hand, the transition from an
diffusive regime to a localized regime for short systems is identified,
suggesting the necessity of a further length scale revealing the system borders
sensibility. On the other hand, we show that the lenght localization and
participation number, do not depended of system size and contact coupling in
the thermodynamic limit. Finally we discuss possible length dependent origins
for the large discrepancies among experimental results for the electronic
transport in DNA sample
Lepton Flavor Violation in Z and Lepton Decays in Supersymmetric Models
The observation of charged lepton flavor non-conservation would be a clear
signature of physics beyond the Standard Model. In particular, supersymmetric
(SUSY) models introduce mixings in the sneutrino and the charged slepton
sectors which could imply flavor-changing processes at rates accessible to
upcoming experiments. In this paper we analyze the possibility to observe Z -->
lep_I lep_J in the GigaZ option of TESLA at DESY. We show that although models
with SUSY masses above the current limits could predict a branching ratio BR(Z
--> mu e) accessible to the experiment, they would imply an unobserved rate of
mu --> e gamma and thus are excluded. In models with a small mixing angle
between the first and the third (or the second and the third) slepton families
GigaZ could observe Z --> tau mu (or Z --> tau e) consistently with present
bounds on lep_J --> lep_I gamma. In contrast, if the mixing angles between the
three slepton families are large the bounds from mu --> e gamma push these
processes below the reach of GigaZ. We show that in this case the masses of the
three slepton families must be strongly degenerated (with mass differences of
order 10^{-3}). We update the limits on the slepton mass insertions
delta_{LL,RR,LR} and discuss the correlation between flavor changing and g_mu-2
in SUSY models.Comment: 23 pages, 6 figures. Version to appear in Phys. Rev.
- âŠ