7,429 research outputs found
Antigen depot is not required for alum adjuvanticity
Alum adjuvants have been in continuous clinical use for more than 80 yr. While the prevailing theory has been that depot formation and the associated slow release of antigen and/or inflammation are responsible for alum enhancement of antigen presentation and subsequent T- and B-cell responses, this has never been formally proven. To examine antigen persistence, we used the chimeric fluorescent protein EαGFP, which allows assessment of antigen presentation in situ, using the Y-Ae antibody. We demonstrate that alum and/or CpG adjuvants induced similar uptake of antigen, and in all cases, GFP signal did not persist beyond 24 h in draining lymph node antigen-presenting cells. Antigen presentation was first detectable on B cells within 6–12 h of antigen administration, followed by conventional dendritic cells (DCs) at 12–24 h, then finally plasmacytoid DCs at 48 h or later. Again, alum and/or CpG adjuvants did not have an effect on the magnitude or sequence of this response; furthermore, they induced similar antigen-specific T-cell activation in vivo. Notably, removal of the injection site and associated alum depot, as early as 2 h after administration, had no appreciable effect on antigen-specific T- and B-cell responses. This study clearly rules out a role for depot formation in alum adjuvant activity
Images in cardiovascular medicine : multiphoton microscopy for three-dimensional imaging of lymphocyte recruitment into apolipoprotein-E-deficient mouse carotid artery
Two recent elegant studies have shown that in apolipoprotein-E– deficient mice, the lamina adventitia is a major site of arterial wall inflammation associated with lymphocyte infiltration into atherosclerotic arteries and with formation of adventitial lymphoid-like tissues.1,2 These results suggest that lymphocyte responses in the lamina adventitia may play a crucial role in atherosclerosis development.1,
A technique for chronic repuncture micropuncture of dog kidney
The precision of kidney micropuncture for exploring changes in glomerular and tubular function was strikingly enhanced by the introduction of the repuncture and re-collection technique [1], thus permitting the use of each tubule as its own control. This procedure has allowed detection of changes in function that were not appreciated previously. However, the technical design of re-collection micropuncture is such that it is mainly applicable to the study of rapid and usually massive changes in homeostasis; exploration of the renal response to chronic, more physiologic maneuvers has been limited to clearance and non-repuncture micropuncture studies.This paper describes a technique for chronic repuncture micropuncture that allows repeat proximal tubule sampling in dogs at an interval of up to 14 days
Late-Type Stars in M31. I.: A Photometric Study of AGB Stars and Metallicity Gradients.
We have imaged five 7\arcmin \x 7\arcmin\ fields in M31 spanning
galactocentric radii from 4 to 32 kpc along the SW-major axis. The fields were
observed through two broad-band (\V\ and \I) and two narrow-band (\CN\ and
\TiO) filters. The broad-band data were used to construct \IvsVI\
color-magnitude diagrams (CMDs) and, in some of our fields, we found
significant numbers of stars in the Cepheid instability strip. A distance
modulus for the Cepheids in the middle field was found that agreed well with
other values in the literature values. The width of the giant branch (GB) in
the \IvsVI\ CMD of all 5 fields was investigated, and we show that in four of
the fields a likely explanation for the GB width is a combination of {\it both}
metallicity and mass variations. Using the broad-band data, the asymptotic
giant branch (AGB) luminosity functions (LFs) were measured in the five fields,
and we show that differences exist between these LFs. We speculate on how the
different star forming histories in the fields may lead to the observed AGB LFs
and GB widths. Using the narrow-band data along with the broad-band data we
separated the AGB stars into carbon-rich (C) and oxygen-rich (M) types. The
carbon stars LFs were used to obtain an estimate for the distance modulus of
M31 which agrees with the value derived from Cepheids. The ratio of C- to
M-stars (C/M) is believed to be an indicator of gaseous chemical abundance at
the time of formation of these stars. We show that the C/M ratio increases
smoothly with galactocentric distance, suggesting an inverse correlation with
metallicity. This is the first demonstration of this effect within a single
extragalactic system. We find that differences in the width of the GB and the
AGB LFs do not significantly affect the C/M ratio. We consider the effect of
the increasing C/M ratio on the ISM in M31, and cite evidence in favor of a
model where the grain composition in M31 is a function of galactocentric
distance.Comment: UUencoded compressed postscript, 3 Figs. available on request.
(Contact [email protected]
WIMP astronomy and particle physics with liquid-noble and cryogenic direct-detection experiments
Once weakly-interacting massive particles (WIMPs) are unambiguously detected
in direct-detection experiments, the challenge will be to determine what one
may infer from the data. Here, I examine the prospects for reconstructing the
local speed distribution of WIMPs in addition to WIMP particle-physics
properties (mass, cross sections) from next-generation cryogenic and
liquid-noble direct-detection experiments. I find that the common method of
fixing the form of the velocity distribution when estimating constraints on
WIMP mass and cross sections means losing out on the information on the speed
distribution contained in the data and may lead to biases in the inferred
values of the particle-physics parameters. I show that using a more general,
empirical form of the speed distribution can lead to good constraints on the
speed distribution. Moreover, one can use Bayesian model-selection criteria to
determine if a theoretically-inspired functional form for the speed
distribution (such as a Maxwell-Boltzmann distribution) fits better than an
empirical model. The shape of the degeneracy between WIMP mass and cross
sections and their offset from the true values of those parameters depends on
the hypothesis for the speed distribution, which has significant implications
for consistency checks between direct-detection and collider data. In addition,
I find that the uncertainties on theoretical parameters depends sensitively on
the upper end of the energy range used for WIMP searches. Better constraints on
the WIMP particle-physics parameters and speed distribution are obtained if the
WIMP search is extended to higher energy (~ 1 MeV).Comment: 25 pages, 27 figures, matches published versio
The Herbertsmithite Hamiltonian: SR measurements on single crystals
We present transverse field muon spin rotation/relaxation measurements on
single crystals of the spin-1/2 kagome antiferromagnet Herbertsmithite. We find
that the spins are more easily polarized when the field is perpendicular to the
kagome plane. We demonstrate that the difference in magnetization between the
different directions cannot be accounted for by Dzyaloshinksii-Moriya type
interactions alone, and that anisotropic axial interaction is present.Comment: 8 pages, 3 figures, accepted to JPCM special issue on geometrically
frustrated magnetis
Kinetics and mechanism of proton transport across membrane nanopores
We use computer simulations to study the kinetics and mechanism of proton
passage through a narrow-pore carbon-nanotube membrane separating reservoirs of
liquid water. Free energy and rate constant calculations show that protons move
across the membrane diffusively in single-file chains of hydrogen-bonded water
molecules. Proton passage through the membrane is opposed by a high barrier
along the effective potential, reflecting the large electrostatic penalty for
desolvation and reminiscent of charge exclusion in biological water channels.
At neutral pH, we estimate a translocation rate of about 1 proton per hour and
tube.Comment: 4 pages, 4 figure
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