186 research outputs found
Epidermolysis Bullosa Dystrophica-Recessive: A Possible Role Of Anchoring Fibrils In The Pathogenesis
The purpose of this study was to define the ultrastructural defects and pathogenesis of epidermolysis bullosa dystrophica-recessive (EBD-R). The only consistent ultrastructural alteration found in EBD-R was an absence of anchoring fibrils. In many specimens of nonblistered, nontraumatized EBD-R skin, absence of anchoring fibrils was the only ultrastructural abnormality observed. The possibility that lack of anchoring fibrils was a secondary change resulting from previous blistering and scarring was eliminated by our observation that anchoring fibrils were consistently absent in the never previously blistered skin of two newborns with EBD-R. In experimentally traumatized skin, the epidermis and dermis separated in the region of the epidermal-dermal junction normally occupied by anchoring fibrils. Basal lamina and dermal microfibril bundles appeared to be normal. Using recombinant grafts, we demonstrated that anchoring fibrils were not formed by EBD-R dermis when combined with EBD-R epidermis or normal epidermis. Anchoring fibrils were formed when normal dermis was combined with normal and EBDR epidermis. These studies indicate that the defect in EBD-R resides in the dermis and that the defect may he associated with impaired formation of anchoring fibrils
Differentiating Anti-Lamina Lucida and Anti-Sublamina Densa Anti-BMZ Antibodies by Indirect Immunofluorescence on 1.0 M Sodium Chloride-Separated Skin
L'immunofluorescence indirecte sur la peau séparée est une méthode fiable pour différencier les anticorps contre la lame transparente et les anticorps contre la sous-lame dense des maladies bulleuses et la différenciation entre les anticorps est essentielle pour un diagnostic exact chez certains malades. Les anticorps contre la lame transparente dans la pemphigoïde bulleuse peuvent présenter plusieurs spécificités
Galactic chemical evolution of heavy elements: from Barium to Europium
We follow the chemical evolution of the Galaxy for elements from Ba to Eu,
using an evolutionary model suitable to reproduce a large set of Galactic
(local and non local) and extragalactic constraints. Input stellar yields for
neutron-rich nuclei have been separated into their s-process and r-process
components. The production of s-process elements in thermally pulsing
asymptotic giant branch stars of low mass proceeds from the combined operation
of two neutron sources: the dominant reaction 13C(alpha,n)16O, which releases
neutrons in radiative conditions during the interpulse phase, and the reaction
22Ne(alpha,n)25Mg, marginally activated during thermal instabilities. The
resulting s-process distribution is strongly dependent on the stellar
metallicity. For the standard model discussed in this paper, it shows a sharp
production of the Ba-peak elements around Z = Z_sun/4. Concerning the r-process
yields, we assume that the production of r-nuclei is a primary process
occurring in stars near the lowest mass limit for Type II supernova
progenitors. The r-contribution to each nucleus is computed as the difference
between its solar abundance and its s-contribution given by the Galactic
chemical evolution model at the epoch of the solar system formation. We compare
our results with spectroscopic abundances of elements from Ba to Eu at various
metallicities (mainly from F and G stars) showing that the observed trends can
be understood in the light of the present knowledge of neutron capture
nucleosynthesis. Finally, we discuss a number of emerging features that deserve
further scrutiny.Comment: 34 pages, 13 figures. accepted by Ap
Geodesic and Path Motion in the Nonsymmetric Gravitational Theory
We study the problem of test-particle motion in the Nonsymmetric
Gravitational Theory (NGT) assuming the four-velocity of the particle is
parallel-transported along the trajectory. The predicted motion is studied on a
static, spherically symmetric background field, with particular attention paid
to radial and circular motions. Interestingly, it is found that the proper time
taken to travel between any two non-zero radial positions is finite. It is also
found that circular orbits can be supported at lower radii than in General
Relativity for certain forms of motion.
We present three interactions which could be used as alternate methods for
coupling a test-particle to the antisymmetric components of the NGT field. One
of these takes the form of a Yukawa force in the weak-field limit of a static,
spherically symmetric field, which could lead to interesting phenomenology.Comment: 17 pages, REVTeX 3.0 with amssymb.st
The barium isotopic mixture for the metal-poor subgiant star HD140283
Current theory regarding heavy element nucleosynthesis in metal-poor
environments states that the r-process would be dominant. The star HD140283 has
been the subject of debate after it appeared in some studies to be dominated by
the s-process. We provide an independent measure of the Ba isotope mixture in
HD140283 using an extremely high quality spectrum and an extensive chi^2
analysis. We exploit hyperfine splitting of the BaII 4554 \AA\ and 4934 \AA\
resonance lines in an effort to constrain the isotope ratio in 1D LTE. Using
the code ATLAS in conjunction with KURUCZ06 model atmospheres we analyse 93 Fe
lines to determine the star's macroturbulence. With this information we
construct a grid of Ba synthetic spectra and, using a \chi^2 code, fit these to
our observed data to determine the isotopic ratio, fodd, which represents the
ratio of odd to even isotopes. We also analyse the Eu lines. We set a new upper
limit of the rotation of HD140283 at vsin{i}\leq3.9\kms, a new upper limit on
[Eu/H] < -2.80 and abundances [Fe/H] = -2.59\pm0.09, [Ba/H] = -3.46\pm0.11.
This leads to a new lower limit on [Ba/Eu] > -0.66. We find that, in the
framework of a 1D LTE analysis, the isotopic ratios of Ba in HD140283 indicate
fodd=0.02\pm0.06, a purely s-process signature. This implies that observations
and analysis do not validate currently accepted theory. We speculate that a 1D
code, due to simplifying assumptions, is not adequate when dealing with
observations with high levels of resolution and S/N because of the turbulent
motions associated with a 3D stellar atmosphere. New approaches to analysing
isotopic ratios, in particular 3D hydrodynamics, need to be considered when
dealing with the levels of detail required to properly determine them. However
published 3D results exacerbate the disagreement between theory and
observation.Comment: 16 pages, 10 figures, 7 tables, 1 online appendix Accepted by A&
Data incongruence and the problem of avian louse phylogeny
Recent studies based on different types of data (i.e. morphological and molecular) have supported conflicting phylogenies for the genera of avian feather lice (Ischnocera: Phthiraptera). We analyse new and published data from morphology and from mitochondrial (12S rRNA and COI) and nuclear (EF1-) genes to explore the sources of this incongruence and explain these conflicts. Character convergence, multiple substitutions at high divergences, and ancient radiation over a short period of time have contributed to the problem of resolving louse phylogeny with the data currently available. We show that apparent incongruence between the molecular datasets is largely attributable to rate variation and nonstationarity of base composition. In contrast, highly significant character incongruence leads to topological incongruence between the molecular and morphological data. We consider ways in which biases in the sequence data could be misleading, using several maximum likelihood models and LogDet corrections. The hierarchical structure of the data is explored using likelihood mapping and SplitsTree methods. Ultimately, we concede there is strong discordance between the molecular and morphological data and apply the conditional combination approach in this case. We conclude that higher level phylogenetic relationships within avian Ischnocera remain extremely problematic. However, consensus between datasets is beginning to converge on a stable phylogeny for avian lice, at and below the familial rank
Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor beta 1
Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1
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