380 research outputs found
Health related quality of life and future treatment preferences of patients with COPD admitted to UK critical care units from CAOS: The COPD & Asthma outcome study
New Results from a Near-Infrared Search for Hidden Broad-Line Regions in Ultraluminous Infrared Galaxies
This paper reports the latest results from a near-infrared search for hidden
broad-line regions (BLRs: FWHM >~ 2,000 km/s) in ultraluminous infrared
galaxies (ULIGs). The new sample contains thirty-nine ULIGs from the 1-Jy
sample selected for their lack of BLRs at optical wavelengths. The results from
this new study are combined with those from our previous optical and
near-infrared surveys to derive the fraction of all ULIGs with optical or
near-infrared signs of genuine AGN activity (either a BLR or [Si VI] emission).
Comparisons of the dereddened emission-line luminosities of the optical or
obscured BLRs detected in the ULIGs of the 1-Jy sample with those of optical
quasars indicate that the obscured AGN/quasar in ULIGs is the main source of
energy in at least 15 -- 25% of all ULIGs in the 1-Jy sample. This fraction is
30 -- 50% among ULIGs with L_ir > 10^{12.3} L_sun. These results are compatible
with those from recent mid-infrared spectroscopic surveys carried out with ISO.
(abridged)Comment: 40 pages including 10 figures and 3 tables (Table 3 should be printed
in landscape mode
Imaging of Ultraluminous Infrared Galaxies in the Near-UV
We present the first ground-based U' (3410 angstroms) images of Ultraluminous
Infrared Galaxies (ULIGs). Strong U' emission (median total M_U' = -20.8) is
seen in all systems and in some cases the extended tidal features (both the
smooth stellar distribution and compact star-forming features) contribute up to
60-80% of the total flux. The star-forming regions in both samples are found to
have ages based on spectral synthesis models in the range 10-100 Myrs, and most
differences in color between them can be attributed to the effects of dust
reddening. Additionally, it is found that star-formation in compact knots in
the tidal tails is most prominent in those ULIGs which have double nuclei,
suggesting that the star-formation rate in the tails peaks prior to the actual
coalescence of the galaxy nuclei and diminishes quickly thereafter. Similar to
results at other wavelengths, the observed star formation at U' can only
account for a small fraction of the known bolometric luminosity of the ULIGs.
Azimuthally averaged radial light profiles at U' are characterized by a sersic
law with index n=2, which is intermediate between an exponential disk and an
r^(-1/4) law and closely resembles the latter at large radii. The implications
of this near-ultraviolet imaging for optical/near-infrared observations of high
redshift counterparts of ULIGs are discussed.Comment: 30 pages, 4 tables, and 9 figures, 2 of which are JPEGs. To appear in
the August, 2000 edition of the Astronomical Journa
Metalloproteinase and inhibitor expression profiling of resorbing cartilage reveals pro-collagenase activation as a critical step for collagenolysis
Excess proteolysis of the extracellular matrix (ECM) of articular cartilage is a key characteristic of arthritis. The main enzymes involved belong to the metalloproteinase family, specifically the matrix metalloproteinases (MMPs) and a group of proteinases with a disintegrin and metalloproteinase domain with thrombospondin motifs (ADAMTS). Chondrocytes are the only cell type embedded in the cartilage ECM, and cell-matrix interactions can influence gene expression and cell behaviour. Thus, although the use of monolayer cultures can be informative, it is essential to study chondrocytes encapsulated within their native environment, cartilage, to fully assess cellular responses. The aim of this study was to profile the temporal gene expression of metalloproteinases and their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), reversion-inducing cysteine-rich protein with Kazal motifs (RECK), and α(2)-macroglobulin (α(2)M), in actively resorbing cartilage. The addition of the pro-inflammatory cytokine combination of interleukin-1 (IL-1) + oncostatin M (OSM) to bovine nasal cartilage induces the synthesis and subsequent activation of pro-metalloproteinases, leading to cartilage resorption. We show that IL-1+OSM upregulated the expression of MMP-1, -2, -3, -9, 12, -13, -14, TIMP-1, and ADAMTS-4, -5, and -9. Differences in basal expression and the magnitude of induction were observed, whilst there was no significant modulation of TIMP-2, -3, RECK, or ADAMTS-15 gene expression. IL-1+OSM downregulated MMP-16,TIMP-4, and α(2)M expression. All IL-1+OSM-induced metalloproteinases showed marked upregulation early in the culture period, whilst inhibitor expression was reduced throughout the stimulation period such that metalloproteinase production would be in excess of inhibitors. Moreover, although pro-collagenases were upregulated and synthesized early (by day 5), collagenolysis became apparent later with the presence of active collagenases (day 10) when inhibitor levels were low. These findings indicate that the activation cascades for pro-collagenases are delayed relative to collagenase expression, further confirm the coordinated regulation of metalloproteinases in actively resorbing cartilage, and support the use of bovine nasal cartilage as a model system to study the mechanisms that promote cartilage degradation
Direct oxide transfer from an η2-keto ligand to generate a cobalt PCcarbeneP(O) pincer complex
We report the direct carbonyl cleavage in a Îș3-PâČ,(η2-C,O),PâČâČ ligand by a monomeric cobalt centre through metalâligand cooperativity. CâO cleavage leads to the formation of a PCcarbeneP(O) pincer ligand with a central alkylidene anchor. A DFT analysis, supported by kinetic studies, suggests that decoordination of a pincer phosphino arm to generate a kinetically accessible free phosphine may be critical in transfer of the oxide to a phosphorus position. Thus, oxide transfer to bisphosphino bidentate co-ligands was also found to be viable, allowing access to the previously reported PCcarbeneP pincer complex (2), where bisphosphines were used as oxide sequestering agents
The development of an internationally valid cancer-specific multi-attribute utility instrument (MAUI) from the EORTC Core HRQOL questionnaire, QLQ-C30
What Powers Ultra-luminous IRAS Galaxies?
We present an ISO SWS and ISOPHOT-S, mid-infrared spectroscopic survey of 15
ultra-luminous IRAS galaxies. We combine the survey results with a detailed
case study, based on near-IR and mm imaging spectroscopy, of one of the sample
galaxies (UGC 5101). We compare the near- and mid-IR characteristics of these
ultra-luminous galaxies to ISO and literature data of thirty starburst and
active galactic nuclei (AGN), template galaxies. We find that
1) 70-80% of the ultra-luminous IRAS galaxies in our sample are predominantly
powered by recently formed massive stars. 20-30% are powered by a central AGN.
These conclusions are based on a new infrared 'diagnostic diagram' involving
the ratio of high to low excitation mid-IR emission lines on the one hand, and
on the strength of the 7.7um PAH feature on the other hand.
2) at least half of the sources probably have simultaneously an active
nucleus and starburst activity in a 1-2 kpc diameter circum-nuclear disk/ring.
3) the mid-infrared emitting regions are highly obscured. After correction
for these extinctions, we estimate that the star forming regions in ULIRGs have
ages between 10^7 and 10^8 years, similar to but somewhat larger than those
found in lower luminosity starburst galaxies.
4) in the sample we have studied there is no obvious trend for the AGN
component to dominate in the most compact, and thus most advanced mergers.
Instead, at any given time during the merger evolution, the time dependent
compression of the circum-nuclear interstellar gas, the accretion rate onto the
central black hole and the associated radiation efficiency may determine
whether star formation or AGN activity dominates the luminosity of the system.Comment: 63 pages postscript (ex. MS Word), 11 postscript and 2 gif figures,
submitted to ApJ. See also
http://www.mpe-garching.mpg.de/ISO/preprint/MPE-IR-97003.htm
HDAC-mediated control of ERK- and PI3K-dependent TGF-ÎČ-induced extracellular matrix-regulating genes
Histone deacetylases (HDACs) regulate the acetylation of histones in the control of gene expression. Many non-histone proteins are also targeted for acetylation, including TGF-Ă signalling pathway components such as Smad2, Smad3 and Smad7. Our studies in mouse C3H10T1/2 fibroblasts suggested that a number of TGF-Ă-induced genes that regulate matrix turnover are selectively regulated by HDACs. Blockade of HDAC activity with trichostatin A (TSA) abrogated the induction of a disintegrin and metalloproteinase 12 (Adam12) and tissue inhibitor of metalloproteinases-1 (Timp-1) genes by TGF-Ă, whereas plasminogen activator inhibitor-1 (Pai-1) expression was unaffected. Analysis of the activation of cell signalling pathways demonstrated that TGF-Ă induced robust ERK and PI3K activation with delayed kinetics compared to the phosphorylation of Smads. The TGF-Ă induction of Adam12 and Timp-1 was dependent on such non-Smad signalling pathways and, importantly, HDAC inhibitors completely blocked their activation without affecting Smad signalling. Analysis of TGF-Ă-induced Adam12 and Timp-1 expression and ERK/PI3K signalling in the presence of semi-selective HDAC inhibitors valproic acid, MS-275 and apicidin implicated a role for class I HDACs. Furthermore, depletion of HDAC3 by RNA interference significantly down-regulated TGF-Ă-induced Adam12 and Timp-1 expression without modulating Pai-1 expression. Correlating with the effect of HDAC inhibitors, depletion of HDAC3 also blocked the activation of ERK and PI3K by TGF-Ă. Collectively, these data confirm that HDACs, and in particular HDAC3, are required for activation of the ERK and PI3K signalling pathways by TGF-Ă and for the subsequent gene induction dependent on these signalling pathways
Protocolised Management In Sepsis (ProMISe): a multicentre randomised controlled trial of the clinical effectiveness and cost-effectiveness of early, goal-directed, protocolised resuscitation for emerging septic shock
Far Infrared Source Counts at 70 and 160 microns in Spitzer Deep Surveys
We derive galaxy source counts at 70 and 160 microns using the Multiband
Imaging Photometer for Spitzer (MIPS) to map the Chandra Deep Field South
(CDFS) and other fields. At 70 microns, our observations extend upwards about 2
orders of magnitude in flux density from a threshold of 15 mJy, and at 160
microns they extend about an order of magnitude upward from 50 mJy. The counts
are consistent with previous observations on the bright end. Significant
evolution is detected at the faint end of the counts in both bands, by factors
of 2-3 over no-evolution models. This evolution agrees well with models that
indicate most ofthe faint galaxies lie at redshifts between 0.7 and 0.9. The
new Spitzer data already resolve about 23% of the Cosmic Far Infrared
Background at 70 microns and about 7% at 160 microns.Comment: Small modifications to match printed version. Models in Differential
Counts plots were changed. MIPS Source Counts are available at:
http://lully.as.arizona.edu/GTODeep/Counts/ . Accepted for Publication in
ApJS Special Issue on Spitze
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