798 research outputs found
Pump-probe scheme for optical coherence tomography using indocyanine green mixed with albumin or human plasma
Use of indocyanine green (ICG) in a pump-probe scheme for OCT is proposed. The study illustrates that ICG in protein solution shows unusual pump-probe imaging potential, indicating its usefulness as a contrast agent for OCT
Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?
We report a Chandra high-energy grating detection of a narrow, redshifted
absorption line superimposed on the red wing of a broad Fe K line in the
quasar E1821+643. The absorption line is detected at a confidence
level, estimated by two different methods, in the range ~2-3 sigma. Although
the detection significance is not high enough to exclude a non-astrophysical
origin, accounting for the absorption feature when modeling the X-ray spectrum
implies that the Fe-K emission line is broad, and consistent with an origin in
a relativistic accretion disk. Ignoring the apparent absorption feature leads
to the conclusion that the Fe-K emission line is narrower, and also affects the
inferred peak energy of the line (and hence the inferred ionization state of
Fe). If the absorption line (at ~6.2 keV in the quasar frame) is real, we argue
that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance
absorption within ~10-20 gravitational radii of the putative central black
hole. The absorption line is not detected in earlier low-energy grating
observations, but is not unequivocally ruled out by these data. The Chandra
high-energy grating Fe K emission line is consistent with an origin
predominantly in Fe I-XVII or so. In a previous LEG observation the line was
double-peaked, at ~6.4 keV and ~6.9 keV (H-like Fe). Such a wide range in
ionization state of Fe is not ruled out by the HEG data and an earlier ASCA
observation, and is suggestive of a complex structure for the line-emitter.Comment: To be published in the Astrophysical Journal, 20 April 2005. 18
pages, ten figures, five of them in color. Four tables. Abstract is
abridged.Corrected typos in author affiliation superscript
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Comparison of different dietary sources of n-3 polyunsaturated fatty acids on immune response in broiler chickens
The study aims to research the effects of varied dietary sources of n-3 polyunsaturated fatty acids (PUFA) on the immune response in broiler chickens with stress on natural killer (NK) cell activity. Diets supplemented with one of the four sources of n-3 PUFA: linseed oil-, echium oil-, fish oil (FO) or algal biomass-enriched diets at levels of 18, 18, 50 and 15 g/kg fresh weight, were provided for one-d-old male Ross 308 broilers, totaling 340 in number, until they were slaughtered. The analyses included total lipid profile using gas chromatography (GC) for plasma, spleen, thymus, and blood. Additionally, NK cell activity and cell proliferation were investigated for thymocytes and splenocytes. The results indicated that the source of n-3 PUFA had a strong influence on fatty acid composition across all tissues. NK activity was highest in splenocytes and PBMCs from broilers fed linseed oil, followed by those fed algal biomass or echium oil, and lowest for those from broilers fed FO. The proliferative response of lymphocytes from algal biomass-fed chickens tended to be the highest, followed by those fed linseed oil in most cases. Lymphocytes from chickens fed fish oil showed the lowest proliferative response. These results could mean that a docosahexaenoic acid (DHA)-rich algal product might enrich chicken meat with n-3 PUFA without significant damaging effects on chicken immunity
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Monounsaturated fats and immune function
Animal studies suggest that olive oil is capable of modulating functions of cells of the immune system in a manner similar to, albeit weaker than, fish oils. There is some evidence that the effects of olive oil on immune function in animal studies are due to oleic acid rather than to trace elements or antioxidants. Importantly, several studies have demonstrated effects of oleic acid-containing diets on in vivo immune responses. In contrast, consumption of a monounsaturated fatty acid (MUFA)-rich diet by humans does not appear to bring about a general suppression of immune cell functions. The effects of this diet in humans are limited to decreasing aspects of adhesion of peripheral blood mononuclear cells, although there are trends towards decreases in natural killer cell activity and proliferation. The lack of a clear effect of MUFA in humans may be attributable to the higher level of monounsaturated fat used in the animal studies, although it is ultimately of importance to examine the effects of intakes which are in no way extreme. The effects of MUFA on adhesion molecules are potentially important, since these molecules appear to have a role in the pathology of a number of diseases involving the immune system. This area clearly deserves further exploration
Coupling between the TRPC3 ion channel and the NCX1 transporter contributed to VEGF-induced ERK1/2 activation and angiogenesis in human primary endothelial cells
This work was directly funded by the Barts and the London National Institute of Health Research (NIHR) Cardiovascular Biomedical Research Unit. Support to PA and MMY by the Barts Health “Diabetic Kidney Disease Centre,” supported and funded by the Barts and the London Charity (Grant Number 577-2348) is gratefully acknowledged. SAE receives funding from The Institute of Cancer Research and Cancer Research United Kingdom Grant C309/A8274. The authors wish to thank Sam Ranasinghe (University College London) for assistance with the FLIPR – Tetra assays
NGC 4388: A Test Case for Relativistic Disk Reflection and Fe K Fluorescence Features
We present a new analysis of the Suzaku X-ray spectrum of the Compton-thin
Seyfert 2 galaxy NGC 4388. The spectrum above 2 keV can be described by a
remarkably simple and rather mundane model, consisting of a uniform, neutral
spherical distribution of matter, with a radial column density of cm, and an Fe abundance of
relative to solar. The model does not require any
phenomenological adjustments to self-consistently account for the low-energy
extinction, the Fe K and Fe K fluorescent emission lines, the Fe
K edge, and the Compton-scattered continuum from the obscuring material. The
spherical geometry is not a unique description, however, and the
self-consistent, solar abundance MYTORUS model, applied with toroidal and
non-toroidal geometries, gives equally good descriptions of the data. In all
cases, the key features of the spectrum are so tightly locked together that for
a wide range of parameters, a relativistic disk-reflection component
contributes no more than 2% to the net spectrum in the 2-20 keV band. We
show that the commonly invoked explanations for weak X-ray reflection features,
namely a truncated and/or very highly ionized disk, do not work for NGC 4388.
If relativistically-broadened Fe K lines and reflection are ubiquitous
in Seyfert 1 galaxies, they should also be ubiquitous in Compton-thin Seyfert 2
galaxies. The case of NGC 4388 shows the need for similar studies of more
Compton-thin AGN to ascertain whether this is true.Comment: MNRAS accepted. 21 pages, 7 figures, 4 tables; Appendix with
historical notes and 1 table. This version: Corrected minor typo and
affiliatio
A Highly Doppler Blueshifted Fe-K Emission Line in the High-Redshift QSO PKS 2149-306
We report the results from an \asca observation of the QSO PKS 2149-306
(z=2.345). We detect an emission line centered at keV in the quasar
frame. Line emission at this energy has not been observed in any other active
galaxy or quasar to date. We present evidence rejecting the possibility that
this line is the result of instrumental artifacts, or a serendipitous source.
The most likely explanation is blueshifted Fe-K emission (the EW is 300+/-200
eV, QSO frame). Bulk velocities of the order of 0.75c are implied by the data.
We show that Fe-K line photons originating in an accretion disk and
Compton-scattering off a leptonic can account for the emission line. Curiously,
if the emission-line feature recently discovered in another quasar PKS
0637752, , is blueshifted Ovii, the Doppler factor is the same
(~2.7) for both.Comment: 15 pages plus 3 figures. Latex with separate .ps files (Accepted by
Astrophysical Journal Letters
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Effects of pelargonidin-3-O-glucoside and its metabolites on lipopolysaccharide-stimulated cytokine production by THP-1 monocytes and macrophages
Epidemiological evidence suggests cardioprotective effects of anthocyanin consumption. This study examined the predominant strawberry anthocyanin, pelargonidin-3-O-glucoside (Pg-3-glc), and three of its plasma metabolites (protocatechuic acid [PCA], 4-hydroxybenzoic acid, and phloroglucinaldehyde [PGA]) for effects on the production of selected cytokines by lipopolysaccharide-stimulated THP-1 monocytes and macrophages. Concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8 and IL-10 were determined using a cytometric bead array kit. PCA at 0.31, 1.25 and 20 μM and PGA at 5 and 20 μM decreased the concentration of IL-6 in the monocyte cultures, but there were no effects on TNF-α, IL-1β, IL-8 and IL-10 and there were no effects of the other compounds. In the macrophage cultures, PGA at 20 μM decreased the concentrations of IL-6 and IL-10, but there was no effect on TNF-α, IL-1β and IL-8 and there were no effects of the other compounds. In conclusion, while the effects of PGA were only observed at the higher, supraphysiological concentration and are thus considered of limited physiological relevance overall, the anti-inflammatory properties of PCA were observed at both the lower, physiologically relevant, and the higher concentrations; however, effects were modest and limited to IL-6 and monocytes. These preliminary data suggest potential for physiologically attainable PCA concentrations to modulate IL-6 production by monocytes
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