595 research outputs found
Transient increase in atherosclerotic plaque macrophage content following Streptococcus pneumoniae pneumonia in ApoE-deficient mice
Introduction: Despite epidemiological associations between community acquired pneumonia (CAP) and myocardial infarction, mechanisms that modify cardiovascular disease during CAP are not well defined. In particular, largely due to a lack of relevant experimental models, the effect of pneumonia on atherosclerotic plaques is unclear. We describe the development of a murine model of the commonest cause of CAP, Streptococcus pneumoniae pneumonia, on a background of established atherosclerosis. We go on to use our model to investigate the effects of pneumococcal pneumonia on atherosclerosis.
Methods: C57BL/6J and ApoE-/- mice were fed a high fat diet to promote atherosclerotic plaque formation. Mice were then infected with a range of S. pneumoniae serotypes (1, 4 or 14) with the aim of establishing a model to study atherosclerotic plaque evolution after pneumonia and bacteremia. Laser capture microdissection of plaque macrophages enabled transcriptomic analysis.
Results: Intratracheal instillation of S. pneumoniae in mice fed a cholate containing diet resulted in low survival rates following infection, suggestive of increased susceptibility to severe infection. Optimization steps resulted in a final model of male ApoE-/- mice fed a Western diet then infected by intranasal instillation of serotype 4 (TIGR4) S. pneumoniae followed by antibiotic administration. This protocol resulted in high rates of bacteremia (88.9%) and survival (88.5%). Pneumonia resulted in increased aortic sinus plaque macrophage content 2 weeks post pneumonia but not at 8 weeks, and no difference in plaque burden or other plaque vulnerability markers were found at either time point. Microarray and qPCR analysis of plaque macrophages identified downregulation of two E3 ubiquitin ligases, Huwe1 and Itch, following pneumonia. Treatment with atorvastatin failed to alter plaque macrophage content or other plaque features.
Discussion: Without antibiotics, ApoE-/- mice fed a high fat diet were highly susceptible to mortality following S. pneumoniae infection. The major infection associated change in plaque morphology was an early increase in plaque macrophages. Our results also hint at a role for the ubiquitin proteasome system in the response to pneumococcal infection in the plaque microenvironment
An eddy-correlation measurement of NO2 flux to vegetation and comparison to O3 flux
Eddy-correlation measurements with a newly developed fast-response NOx sensor indicate that the deposition velocity at a height of about 6m above a soybean field has a maximum value near 0.6cms-1 for NOx and is usually about 2/3 ofthat found for ozone. In these studies, over 90% of the NOx is NO2. The corresponding minimum surface resistance for NOx calculated as the quantity remaining after atmospheric resistances are subtracted is about 1.3 s cm-1, which is larger than expected on the basis of leaf stomatal resistance alone. Emission of NO from sites in the plant canopy and soil where NO2 is deposited and reduced to NO or release of NOx as a result of biological activity may have lessened the downward fluxes of NOx as measured. During windy conditions at night, surface resistances are found to have values of about 15scm-1 for NOx (again, greater than 90% NO2) and 1.8scm-1 for O3, corresponding to deposition velocities of 0.05cms-1 and 0.3cms-1, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24138/1/0000395.pd
Cosmological structure formation with clustering quintessence
We study large-scale structure formation in the presence of a quintessence
component with zero speed of sound in the framework of Eulerian Perturbation
Theory. Due to the absence of pressure gradients, quintessence and dark matter
are comoving and can be studied as a unique fluid in terms of the total energy
density contrast and the common velocity. In this description the clustering of
quintessence enhances the linear term proportional to the velocity divergence
in the continuity equation by a factor (1+w) Omega_Q / Omega_m. This is
responsible for a rapid evolution of the growth rate at low redshifts, and
modifies the standard relation between the velocity divergence and the growth
factor. For the total fluid, the solutions for the linear growth function and
growth rate can be written in integral forms and admit simple fitting formulae,
as in the LambdaCDM case. At second order in perturbation theory, we derive an
explicit expression for the kernels F_2 and G_2. They receive modifications of
the order of the ratio between quintessence and total energy density
perturbations, which affect the corresponding tree-level bispectra. We finally
compute the cumulative signal-to-noise in the power spectrum, bispectrum and
reduced bispectrum, expected for departures from a LambdaCDM cosmology both in
the clustering and smooth quintessence scenarios. The reduced bispectrum, in
particular, receives sensible modifications only in the clustering case and can
potentially be used to detect or rule out the model.Comment: 36 pages, 11 figures. Replaced to match published version. Two
figures added and minor revision
Measurement of the open-charm contribution to the diffractive proton structure function
Production of D*+/-(2010) mesons in diffractive deep inelastic scattering has
been measured with the ZEUS detector at HERA using an integrated luminosity of
82 pb^{-1}. Diffractive events were identified by the presence of a large
rapidity gap in the final state. Differential cross sections have been measured
in the kinematic region 1.5 < Q^2 < 200 GeV^2, 0.02 < y < 0.7, x_{IP} < 0.035,
beta 1.5 GeV and |\eta(D*+/-)| < 1.5. The measured cross
sections are compared to theoretical predictions. The results are presented in
terms of the open-charm contribution to the diffractive proton structure
function. The data demonstrate a strong sensitivity to the diffractive parton
densities.Comment: 35 pages, 11 figures, 6 table
Search for lepton-flavor violation at HERA
A search for lepton-flavor-violating interactions and has been performed with the ZEUS detector using the entire HERA I
data sample, corresponding to an integrated luminosity of 130 pb^{-1}. The data
were taken at center-of-mass energies, , of 300 and 318 GeV. No
evidence of lepton-flavor violation was found, and constraints were derived on
leptoquarks (LQs) that could mediate such interactions. For LQ masses below
, limits were set on , where
is the coupling of the LQ to an electron and a
first-generation quark , and is the branching ratio of
the LQ to the final-state lepton ( or ) and a quark . For
LQ masses much larger than , limits were set on the four-fermion
interaction term for LQs that couple to an electron and a quark
and to a lepton and a quark , where and are
quark generation indices. Some of the limits are also applicable to
lepton-flavor-violating processes mediated by squarks in -Parity-violating
supersymmetric models. In some cases, especially when a higher-generation quark
is involved and for the process , the ZEUS limits are the most
stringent to date.Comment: 37 pages, 10 figures, Accepted by EPJC. References and 1 figure (Fig.
6) adde
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
Multijet production in neutral current deep inelastic scattering at HERA and determination of alpha_s
Multijet production rates in neutral current deep inelastic scattering have
been measured in the range of exchanged boson virtualities 10 < Q2 < 5000 GeV2.
The data were taken at the ep collider HERA with centre-of-mass energy sqrt(s)
= 318 GeV using the ZEUS detector and correspond to an integrated luminosity of
82.2 pb-1. Jets were identified in the Breit frame using the k_T cluster
algorithm in the longitudinally invariant inclusive mode. Measurements of
differential dijet and trijet cross sections are presented as functions of jet
transverse energy E_{T,B}{jet}, pseudorapidity eta_{LAB}{jet} and Q2 with
E_{T,B}{jet} > 5 GeV and -1 < eta_{LAB}{jet} < 2.5. Next-to-leading-order QCD
calculations describe the data well. The value of the strong coupling constant
alpha_s(M_Z), determined from the ratio of the trijet to dijet cross sections,
is alpha_s(M_Z) = 0.1179 pm 0.0013(stat.) {+0.0028}_{-0.0046}(exp.)
{+0.0064}_{-0.0046}(th.)Comment: 22 pages, 5 figure
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