577 research outputs found
Connective tissue activation. xxxv. detection of connective tissue activating peptide–iii isoforms in synovium from osteoarthritis and rheumatoid arthritis patients: patterns of interaction with other synovial cytokines in cell culture
Objective. To determine whether extracts of unincubated osteoarthritis (OA) and rheumatoid arthritis (RA) synovial tissue contain connective tissue activating peptide–III (CTAP-III) isoforms and prostaglandin E 2 (PGE 2 ), and whether such extracts have growth-promoting activity, and to determine whether binary combinations of CTAP-III with other cytokines reported to be present in synovial tissue lead to synergistic, additive, or inhibitory effects on growth. Methods. Acid–ethanol extracts of human synovium were examined for growth-promoting activity by measuring formation of 14 C-glycosaminoglycan ( 14 CGAG) and 3 H-DNA in synovial cell cultures; PGE 2 was measured by enzyme immunoassay, and CTAP-III isoforms were identified by Western blotting of extracted proteins separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Growth-promoting activity of CTAP-III and other cytokines was tested in synovial cultures treated with the agonists singly and in binary combination, by measuring changes in synthesis of 14 C-GAG and 3 H-DNA. Results. Platelet-derived CTAP-III and a cleavage isoform with the electrophoretic mobility of CTAP-III–des 1–15/neutrophil-activating peptide–2 (NAP-2) and PGE 2 were found in biologically active extracts of synovial samples from patients with RA and OA. Five growth factors (recombinant epidermal growth factor [rEGF], recombinant interleukin-1Β [rIL-1Β], basic fibroblast growth factor [bFGF], PGE 1 , and PGE 2 ) in binary combination with CTAP-III showed synergism in stimulating GAG synthesis; two (recombinant platelet-derived growth factor type BB [rPDGF-BB] and recombinant transforming growth factor Β [rTGFΒ]) had an additive effect. In combination with CTAP-III, rEGF and rPDGF-BB had a synergistic effect in promoting DNA synthesis, rTGFΒ and rbFGF had an additive effect, and rIL-1Β, PGE 1 , and PGE 2 were antagonistic. Conclusions. The results suggest that, in addition to endogenous factors, CTAP-III and other plateletderived cytokines may play roles in regulating synovial cell metabolism in RA and OA, and that combinations of growth factors may be more significant than single agents in amplification or suppression of important cell functions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37793/1/1780350712_ftp.pd
Connective tissue activation
Four normal (NF) and 4 scleroderma skin fibro-blast (SF) strains were compared with respect to 1) basal 14 C-glucosamine and 35 SO 4 -labeled glycosaminoglycan (GAG) synthesis, 2) responsiveness to autacoid mediators, and 3) performance following maximal stimulation. Under basal conditions, SF synthesized and secreted 2–3 times more radioactive hyaluronic acid than the NF ( P < 0.001); molecular volume by gel chromatography was similar and suggested a high molecular weight product. SF were essentially as responsive to normal lymphoid and platelet factors as were NF. No consistent qualitative or quantitative differences in sulfated GAG synthesis were noted between the 2 groups of cells. Incubation of NF and SF with a false “core protein” such as p-nitrophenyl-Β-D-xyloside suggested that synthesis of the core protein was rate limiting; SF and NF were equally facile in SO 4 -GAG chain synthesis in the presence of a Β-xyloside. SF appear to retain in vitro a partially activated state for many generations, at least with respect to hyaluronic acid synthesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37761/1/1780261109_ftp.pd
Testing Hydrodynamic Models of LMC X-4 with UV and X-ray Spectra
We compare the predictions of hydrodynamic models of the LMC X-4 X-ray binary
system with observations of UV P Cygni lines with the GHRS and STIS
spectrographs on the Hubble Space Telescope. The hydrodynamic model determines
density and velocity fields of the stellar wind, wind-compressed disk,
accretion stream, Keplerian accretion disk, and accretion disk wind. We use a
Monte Carlo code to determine the UV P Cygni line profiles by simulating the
radiative transfer of UV photons that originate on the star and are scattered
in the wind. The qualitative orbital variation predicted is similar to that
observed, although the model fails to reproduce the strong orbital asymmetry
(the observed absorption is strongest for phi>0.5). The model predicts a
mid-eclipse X-ray spectrum, due almost entirely to Compton scattering, with a
factor 4 less flux than observed with ASCA. We discuss how the model may need
to be altered to explain the spectral variability of the system.Comment: 11 figures, accepted by Ap
Connective tissue activation. xxxvi. the origin, variety, distribution, and biologic fate of connective tissue activating peptide–iii isoforms: characteristics in patients with rheumatic, renal, and arterial disease
Objective. To determine the origin, distribution, and biologic fate of platelet-derived connective tissue activating peptide–III (CTAP-III), to define the relative amounts of the antigen forms (CTAP-III, betathromboglobulin [Β-TG], neutrophil activating peptide–2 [NAP-2]) in plasma of normal persons and those with rheumatic or end-stage renal disease, and to define the isoforms of CTAP-III in platelets, plasma, transudates, and tissue deposits. Methods. CTAP-III in plasma was measured by enzyme-linked immunosorbent assay, and growth promoting activity of CTAP-III isoforms was tested in synovial and peritoneal cell cultures by measuring increased synthesis of 14 C-glycosaminoglycan ( 14 C-GAG) and 3 H-DNA. Isolated CTAP-III was characterized by Western blotting, microsequencing, and mass spectrometry. Results. CTAP-III was the primary isoform of this antigen family in normal platelets and platelet-rich plasma; Β-TG and NAP-2 accounted for 90%), and Β-TG was the most rare (0–1%). Deposition of CTAP-III in tissues, such as synovium, spleen, and kidney, is associated with partial processing to NAP-2–like isoforms and the potential to induce neutrophil and fibroblast activation in patients with rheumatic or end-stage renal disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37798/1/1780360816_ftp.pd
Time Dependent Monte Carlo Radiative Transfer Calculations For 3-Dimensional Supernova Spectra, Lightcurves, and Polarization
We discuss Monte-Carlo techniques for addressing the 3-dimensional
time-dependent radiative transfer problem in rapidly expanding supernova
atmospheres. The transfer code SEDONA has been developed to calculate the
lightcurves, spectra, and polarization of aspherical supernova models. From the
onset of free-expansion in the supernova ejecta, SEDONA solves the radiative
transfer problem self-consistently, including a detailed treatment of gamma-ray
transfer from radioactive decay and with a radiative equilibrium solution of
the temperature structure. Line fluorescence processes can also be treated
directly. No free parameters need be adjusted in the radiative transfer
calculation, providing a direct link between multi-dimensional hydrodynamical
explosion models and observations. We describe the computational techniques
applied in SEDONA, and verify the code by comparison to existing calculations.
We find that convergence of the Monte Carlo method is rapid and stable even for
complicated multi-dimensional configurations. We also investigate the accuracy
of a few commonly applied approximations in supernova transfer, namely the
stationarity approximation and the two-level atom expansion opacity formalism.Comment: 16 pages, ApJ accepte
Three-Dimensional Simulations of Inflows Irradiated by a Precessing Accretion Disk in Active Galactic Nuclei: Formation of Outflows
We present three-dimensional (3-D) hydrodynamical simulations of gas flows in
the vicinity of an active galactic nucleus (AGN) powered by a precessing
accretion disk. We consider the effects of the radiation force from such a disk
on its environment on a relatively large scale (up to ~10 pc. We implicitly
include the precessing disk by forcing the disk radiation field to precess
around a symmetry axis with a given period () and a tilt angle ().
We study time evolution of the flows irradiated by the disk, and investigate
basic dependencies of the flow morphology, mass flux, angular momentum on
different combinations of and . We find the gas flow settles into a
configuration with two components, (1) an equatorial inflow and (2) a bipolar
inflow/outflow with the outflow leaving the system along the poles (the
directions of disk normals). However, the flow does not always reach a steady
state. We find that the maximum outflow velocity and the kinetic outflow power
at the outer boundary can be reduced significantly with increasing . We
also find that of the mass inflow rate across the inner boundary does not
change significantly with increasing . (Abbreviated)Comment: Accepted for publication in ApJ. 15 pages, 7 figures. A version with
full resolution figures can be downloaded from
http://www.physics.unlv.edu/~rk/preprint/precess.pd
Models of X-ray Photoionization in LMC X-4: Slices of a Stellar Wind
We show that the orbital variation in the UV P Cygni lines of the X-ray
binary LMC X-4 results when X-rays photoionize nearly the entire region outside
of the X-ray shadow of the normal star. We fit models to HST GHRS observations
of N V and C IV P Cygni line profiles. Analytic methods assuming a spherically
symmetric wind show that the wind velocity law is well-fit by v~(1-1/r)^beta,
where beta is likely 1.4-1.6 and definitely <2.5. Escape probability models can
fit the observed P Cygni profiles, and provide measurements of the stellar wind
parameters. The fits determine Lx/Mdot=2.6+/-0.1 x10^43 erg/s/Msun yr, where Lx
is the X-ray luminosity and Mdot is the mass-loss rate of the star. Allowing an
inhomogeneous wind improves the fits. IUE spectra show greater P Cygni
absorption during the second half of the orbit than during the first. We
discuss possible causes of this effect.Comment: 56 pages, 12 figures, to be published in the Astrophysical Journa
Analysis of the Flux and Polarization Spectra of the Type Ia Supernova SN 2001el: Exploring the Geometry of the High-velocity Ejecta
SN 2001el is the first normal Type Ia supernova to show a strong, intrinsic
polarization signal. In addition, during the epochs prior to maximum light, the
CaII IR triplet absorption is seen distinctly and separately at both normal
photospheric velocities and at very high velocities. The high-velocity triplet
absorption is highly polarized, with a different polarization angle than the
rest of the spectrum. The unique observation allows us to construct a
relatively detailed picture of the layered geometrical structure of the
supernova ejecta: in our interpretation, the ejecta layers near the photosphere
(v \approx 10,000 km/s) obey a near axial symmetry, while a detached,
high-velocity structure (v \approx 18,000-25,000 km/s) with high CaII line
opacity deviates from the photospheric axisymmetry. By partially obscuring the
underlying photosphere, the high-velocity structure causes a more incomplete
cancellation of the polarization of the photospheric light, and so gives rise
to the polarization peak and rotated polarization angle of the high-velocity IR
triplet feature. In an effort to constrain the ejecta geometry, we develop a
technique for calculating 3-D synthetic polarization spectra and use it to
generate polarization profiles for several parameterized configurations. In
particular, we examine the case where the inner ejecta layers are ellipsoidal
and the outer, high-velocity structure is one of four possibilities: a
spherical shell, an ellipsoidal shell, a clumped shell, or a toroid. The
synthetic spectra rule out the spherical shell model, disfavor a toroid, and
find a best fit with the clumped shell. We show further that different
geometries can be more clearly discriminated if observations are obtained from
several different lines of sight.Comment: 14 pages (emulateapj5) plus 18 figures, accepted by The Astrophysical
Journa
Conservative formulations of general relativistic kinetic theory
Experience with core-collapse supernova simulations shows that accurate
accounting of total particle number and 4-momentum can be a challenge for
computational radiative transfer. This accurate accounting would be facilitated
by the use of particle number and 4-momentum transport equations that allow
transparent conversion between volume and surface integrals in both
configuration and momentum space. Such conservative formulations of general
relativistic kinetic theory in multiple spatial dimensions are presented in
this paper, and their relevance to core-collapse supernova simulations is
described.Comment: 48 page
Instabilities in the Envelopes and Winds of Very Massive Stars
The high luminosity of Very Massive Stars (VMS) means that radiative forces
play an important, dynamical role both in the structure and stability of their
stellar envelope, and in driving strong stellar-wind mass loss. Focusing on the
interplay of radiative flux and opacity, with emphasis on key distinctions
between continuum vs. line opacity, this chapter reviews instabilities in the
envelopes and winds of VMS. Specifically, we discuss how: 1) the iron opacity
bump can induce an extensive inflation of the stellar envelope; 2) the density
dependence of mean opacity leads to strange mode instabilities in the outer
envelope; 3) desaturation of line-opacity by acceleration of near-surface
layers initiates and sustains a line-driven stellar wind outflow; 4) an
associated line-deshadowing instability leads to extensive small-scale
structure in the outer regions of such line-driven winds; 5) a star with
super-Eddington luminosity can develop extensive atmospheric structure from
photon bubble instabilities, or from stagnation of flow that exceeds the
"photon tiring" limit; 6) the associated porosity leads to a reduction in
opacity that can regulate the extreme mass loss of such continuum-driven winds.
Two overall themes are the potential links of such instabilities to Luminous
Blue Variable (LBV) stars, and the potential role of radiation forces in
establishing the upper mass limit of VMS.Comment: 44 pages, 13 figures. Chapter to appear in the book "Very Massive
Stars in the Local Universe", Springer, J.S. Vink, e
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