152 research outputs found
Coexistence of posterior cerebral circulation anatomical variations andbasilar artery aneurysms : case-control study
Background: The anatomy of arteries supplying blood to the brain often varies among the population. It applies particularly to posterior cerebral circulation. The impact of its anatomy variabilities on the formation of intracranial aneurysms has not been determined yet. The aim was to find out if posterior cerebral circulation anatomy variations coexist with basilar artery aneurysms (BAAs). We retrospectively analyzed 27 patients with BAA and a group of 30 patients matched by gender and age but without BAA. In both groups together most (66.67%) of patients were female and the average age was 59.75 ± 10.91. All of the patients had Computed Tomography performed. We assessed the occurrence of BAA, basilar artery (BA) diameter, vertebral artery (VA) diameter, posterior cerebral artery (PCA) diameter, and if patients had hypoplastic VA or PCA. Results: The presence of right VA hypoplasia significantly increased the risk of BAA occurrence (48.15% vs. 16.67%; p = 0.011). The occurrence of hypoplastic VA on either side was significantly associated with the risk of BAA formation (59.26% vs. 26.67%; p = 0.013). Patients with BAA had slightly larger left PCA diameter 1cm after division (1.96 ± 0.51 vs. 1.64 ± 0.42; p = 0.014) in comparison to those without BAA. Additionally, hypoplastic right PCA occurred more often in patients with BAA (22.22% vs. 0%; p = 0.022). Conclusions: We can conclude that the anatomy of PCA and VA affects the occurrence of BAA.
Hypoplastic VA, the presence of wider left PCA and hypoplastic right PCA may be factors that coexist with BAA occurrence
The Nature of Composite LINER/HII Galaxies, As Revealed from High-Resolution VLA Observations
A sample of 37 nearby galaxies displaying composite LINER/HII and pure HII
spectra was observed with the VLA in an investigation of the nature of their
weak radio emission. The resulting radio contour maps overlaid on optical
galaxy images are presented here, together with an extensive literature list
and discussion of the individual galaxies. Radio morphological data permit
assessment of the ``classical AGN'' contribution to the global activity
observed in these ``transition'' LINER galaxies. One in five of the latter
objects display clear AGN characteristics: these occur exclusively in
bulge-dominated hosts.Comment: 31 pages, 27 figures, accepted by ApJ
The Radio Properties of Composite LINER/HII Galaxies
Arcsec-resolution VLA observations -- newly obtained as well as published --
of 40 nearby galaxies are discussed, completing a study of the radio properties
of a magnitude-limited sample of nearby galaxies of the composite LINER/HII
type. Our results reveal an overall detection rate of at least 25% AGN
candidates among these composite sources. The general properties of these AGN
candidates, as compared to non-AGN composite sources and HII galaxies, are
discussed.Comment: Accepted for publication in ApJ
V*-algebras, independence algebras and logic
Independence algebras were introduced in the early 1990s by specialists in semigroup theory, as a tool to explain similarities between the transformation monoid on a set and the endomorphism monoid of a vector space. It turned out that these algebras had already been defined and studied in the 1960s, under the name of v*-algebras, by specialists in universal algebra (and statistics). Our goal is to complete this picture by discussing how, during the middle period, independence algebras began to play a very important role in logic
CYLD regulates keratinocyte differentiation and skin cancer progression in humans
CYLD is a gene mutated in familial cylindromatosis and related diseases, leading to the development of skin appendages tumors. Although the deubiquitinase CYLD is a skin tumor suppressor, its role in skin physiology is unknown. Using skin organotypic cultures as experimental model to mimic human skin, we have found that CYLD acts as a regulator of epidermal differentiation in humans through the JNK signaling pathway. We have determined the requirement of CYLD for the maintenance of epidermal polarity, keratinocyte differentiation and apoptosis. We show that CYLD overexpression increases keratinocyte differentiation while CYLD loss of function impairs epidermal differentiation. In addition, we describe the important role of CYLD in the control of human non-melanoma skin cancer progression. Our results show the reversion of the malignancy of human squamous cell carcinomas that express increased levels of CYLD, while its functional inhibition enhances the aggressiveness of these tumors which progress toward spindle cell carcinomas. We have found that the mechanisms through which CYLD regulates skin cancer progression include the control of tumor differentiation, angiogenesis and cell survival. These findings of the role of CYLD in human skin cancer prognosis make our results relevant from a therapeutic point of view, and open new avenues for exploring novel cancer therapies
Comparison of 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine-enhanced MRI in 471 patients with known or suspected renal lesions: results of a multicenter, single-blind, interindividual, randomized clinical phase III trial
Division Algebras and Quantum Theory
Quantum theory may be formulated using Hilbert spaces over any of the three
associative normed division algebras: the real numbers, the complex numbers and
the quaternions. Indeed, these three choices appear naturally in a number of
axiomatic approaches. However, there are internal problems with real or
quaternionic quantum theory. Here we argue that these problems can be resolved
if we treat real, complex and quaternionic quantum theory as part of a unified
structure. Dyson called this structure the "three-fold way". It is perhaps
easiest to see it in the study of irreducible unitary representations of groups
on complex Hilbert spaces. These representations come in three kinds: those
that are not isomorphic to their own dual (the truly "complex"
representations), those that are self-dual thanks to a symmetric bilinear
pairing (which are "real", in that they are the complexifications of
representations on real Hilbert spaces), and those that are self-dual thanks to
an antisymmetric bilinear pairing (which are "quaternionic", in that they are
the underlying complex representations of representations on quaternionic
Hilbert spaces). This three-fold classification sheds light on the physics of
time reversal symmetry, and it already plays an important role in particle
physics. More generally, Hilbert spaces of any one of the three kinds - real,
complex and quaternionic - can be seen as Hilbert spaces of the other kinds,
equipped with extra structure.Comment: 30 pages, 3 encapsulated Postscript figure
CYLD Enhances Severe Listeriosis by Impairing IL-6/STAT3-Dependent Fibrin Production
The facultative intracellular bacterium Listeria monocytogenes (Lm) may cause severe infection in humans and livestock. Control of acute listeriosis is primarily dependent on innate immune responses, which are strongly regulated by NF-kappa B, and tissue protective factors including fibrin. However, molecular pathways connecting NF-kappa B and fibrin production are poorly described. Here, we investigated whether the deubiquitinating enzyme CYLD, which is an inhibitor of NF-kappa B-dependent immune responses, regulated these protective host responses in murine listeriosis. Upon high dose systemic infection, all C57BL/6 Cyld(-/-) mice survived, whereas 100% of wildtype mice succumbed due to severe liver pathology with impaired pathogen control and hemorrhage within 6 days. Upon in vitro infection with Lm, CYLD reduced NF-kappa B-dependent production of reactive oxygen species, interleukin (IL)-6 secretion, and control of bacteria in macrophages. Furthermore, Western blot analyses showed that CYLD impaired STAT3-dependent fibrin production in cultivated hepatocytes. Immunoprecipitation experiments revealed that CYLD interacted with STAT3 in the cytoplasm and strongly reduced K63-ubiquitination of STAT3 in IL-6 stimulated hepatocytes. In addition, CYLD diminished IL-6-induced STAT3 activity by reducing nuclear accumulation of phosphorylated STAT3. In vivo, CYLD also reduced hepatic STAT3 K63-ubiquitination and activation, NF-kappa B activation, IL-6 and NOX2 mRNA production as well as fibrin production in murine listeriosis. In vivo neutralization of IL-6 by anti-IL-6 antibody, STAT3 by siRNA, and fibrin by warfarin treatment, respectively, demonstrated that IL-6-induced, STAT3-mediated fibrin production significantly contributed to protection in Cyld(-/-) mice. In addition, in vivo Cyld siRNA treatment increased STAT3 phosphorylation, fibrin production, pathogen control and survival of Lm-infected WT mice illustrating that therapeutic inhibition of CYLD augments the protective NF-kappa B/IL-6/STAT3 pathway and fibrin production
Origin of Galactic and Extragalactic Magnetic Fields
A variety of observations suggest that magnetic fields are present in all
galaxies and galaxy clusters. These fields are characterized by a modest
strength (10^{-7}-10^{-5} G) and huge spatial scale (~Mpc). It is generally
assumed that magnetic fields in spiral galaxies arise from the combined action
of differential rotation and helical turbulence, a process known as the
alpha-omega dynamo. However fundamental questions concerning the nature of the
dynamo as well as the origin of the seed fields necessary to prime it remain
unclear. Moreover, the standard alpha-omega dynamo does not explain the
existence of magnetic fields in elliptical galaxies and clusters. The author
summarizes what is known observationally about magnetic fields in galaxies,
clusters, superclusters, and beyond. He then reviews the standard dynamo
paradigm, the challenges that have been leveled against it, and several
alternative scenarios. He concludes with a discussion of astrophysical and
early Universe candidates for seed fields.Comment: 67 pages, 17 figures, accepted for publication in Reviews of Modern
Physic
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