473 research outputs found
Femoral Bâcell neurolymphomatosis in a horse with multicentric lymphoma
An 18âyearâold Freiberger gelding was presented with a history of intermittent left hindlimb lameness after an acute onset 2âweeks prior to referral. The lameness had not responded to antiâinflammatory therapy prescribed by the referring veterinarian. Physical, orthopaedic and neurological examinations revealed signs compatible with ipsilateral femoral nerve dysfunction. Transrectal sonographic examination showed a marked increase in the diameter of the left femoral nerve. The results of electromyography of the left hind quadriceps muscle were compatible with denervation attributable to neuropathy. Evaluation of cerebral spinal fluid (CSF) revealed pleocytosis consisting of mediumâsized lymphocytes, 5%â10% of which were positive for CD3 and CD79a. Neoplasia was suspected and steroid therapy was started. However, exacerbation of the clinical signs occurred and the horse was euthanised. Histopathological evaluation showed neurolymphomatosis of the left femoral nerve as the cause of the lameness. Infiltration of tumour cells was also seen to a lesser extent in the right femoral nerve, spinal cord, various parts of the cardiovascular system, renal capsules, an abdominal lymph node and the subcutis of the left stifle and upper lip. Histochemical evaluation revealed 60%â70% of the neoplastic lymphocytes were positive for CD20 and CD79a and up to 40% were positive for CD3. This report describes the uniqueness of a femoral mononeuropathy as the main clinical finding of Bâcell neurolymphomatosis and multicentric lymphoma
Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon; I. V2028 Cyg
We present results of nearly six years of spectroscopic observations of the
B[e] star V2028 Cyg. The presence of the cold-type absorption lines combined
with a hot-type spectrum indicate the binarity of this object. Since B[e] stars
are embedded in an extended envelope, the usage of common stellar atmosphere
models for the analysis is quite inappropriate. Therefore, we focus on the
analysis of the long-term spectral line variations in order to determine the
nature of this object. We present the time dependences of the equivalent width
and radial velocities of the H alpha line, [O I] 6300 A, Fe II 6427, 6433, and
6456 A lines. The bisector variations and line intensities are shown for the H
alpha line. The radial velocities are also measured for the absorption lines of
the K component. No periodic variation is found. The observed data show
correlations between the measured quantities, which can be used in future
modelling
On Invariant Notions of Segre Varieties in Binary Projective Spaces
Invariant notions of a class of Segre varieties \Segrem(2) of PG(2^m - 1,
2) that are direct products of copies of PG(1, 2), being any positive
integer, are established and studied. We first demonstrate that there exists a
hyperbolic quadric that contains \Segrem(2) and is invariant under its
projective stabiliser group \Stab{m}{2}. By embedding PG(2^m - 1, 2) into
\PG(2^m - 1, 4), a basis of the latter space is constructed that is invariant
under \Stab{m}{2} as well. Such a basis can be split into two subsets whose
spans are either real or complex-conjugate subspaces according as is even
or odd. In the latter case, these spans can, in addition, be viewed as
indicator sets of a \Stab{m}{2}-invariant geometric spread of lines of PG(2^m
- 1, 2). This spread is also related with a \Stab{m}{2}-invariant
non-singular Hermitian variety. The case is examined in detail to
illustrate the theory. Here, the lines of the invariant spread are found to
fall into four distinct orbits under \Stab{3}{2}, while the points of PG(7,
2) form five orbits.Comment: 18 pages, 1 figure; v2 - version accepted in Designs, Codes and
Cryptograph
Constraining Antimatter Domains in the Early Universe with Big Bang Nucleosynthesis
We consider the effect of a small-scale matter-antimatter domain structure on
big bang nucleosynthesis and place upper limits on the amount of antimatter in
the early universe. For small domains, which annihilate before nucleosynthesis,
this limit comes from underproduction of He-4. For larger domains, the limit
comes from He-3 overproduction. Most of the He-3 from antiproton-helium
annihilation is annihilated also. The main source of He-3 is
photodisintegration of He-4 by the electromagnetic cascades initiated by the
annihilation.Comment: 4 pages, 2 figures, revtex, (slightly shortened
Investigation of Mitochondrial Dysfunction by Sequential Microplate-Based Respiration Measurements from Intact and Permeabilized Neurons
Mitochondrial dysfunction is a component of many neurodegenerative conditions. Measurement of oxygen consumption from intact neurons enables evaluation of mitochondrial bioenergetics under conditions that are more physiologically realistic compared to isolated mitochondria. However, mechanistic analysis of mitochondrial function in cells is complicated by changing energy demands and lack of substrate control. Here we describe a technique for sequentially measuring respiration from intact and saponin-permeabilized cortical neurons on single microplates. This technique allows control of substrates to individual electron transport chain complexes following permeabilization, as well as side-by-side comparisons to intact cells. To illustrate the utility of the technique, we demonstrate that inhibition of respiration by the drug KB-R7943 in intact neurons is relieved by delivery of the complex II substrate succinate, but not by complex I substrates, via acute saponin permeabilization. In contrast, methyl succinate, a putative cell permeable complex II substrate, failed to rescue respiration in intact neurons and was a poor complex II substrate in permeabilized cells. Sequential measurements of intact and permeabilized cell respiration should be particularly useful for evaluating indirect mitochondrial toxicity due to drugs or cellular signaling events which cannot be readily studied using isolated mitochondria
Potentiation of the glutamatergic synaptic input to rat locus coeruleus neurons by P2X7 receptors
Locus coeruleus (LC) neurons in a rat brain slice preparation were superfused with a Mg2+-free and bicuculline-containing external medium. Under these conditions, glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) were recorded by means of the whole-cell patch-clamp method. ATP, as well as its structural analogue 2-methylthio ATP (2-MeSATP), both caused transient inward currents, which were outlasted by an increase in the frequency but not the amplitude of the sEPSCs. PPADS, but not suramin or reactive blue 2 counteracted both effects of 2-MeSATP. By contrast, α,ÎČ-methylene ATP (α,ÎČ-meATP), UTP and BzATP did not cause an inward current response. Of these latter agonists, only BzATP slightly facilitated the sEPSC amplitude and strongly potentiated its frequency. PPADS and Brilliant Blue G, as well as fluorocitric acid and aminoadipic acid prevented the activity of BzATP. Furthermore, BzATP caused a similar facilitation of the miniature (m)EPSC (recorded in the presence of tetrodotoxin) and sEPSC frequencies (recorded in its absence). Eventually, capsaicin augmented the frequency of the sEPSCs in a capsazepine-, but not PPADS-antagonizable, manner. In conclusion, the stimulation of astrocytic P2X7 receptors appears to lead to the outflow of a signalling molecule, which presynaptically increases the spontaneous release of glutamate onto LC neurons from their afferent fibre tracts. It is suggested, that the two algogenic compounds ATP and capsaicin utilise separate receptor systems to potentiate the release of glutamate and in consequence to increase the excitability of LC neurons. © 2010 Springer Science+Business Media B.V
Black Hole Entropy and Finite Geometry
It is shown that the symmetric entropy formula describing black
holes and black strings in D=5 is intimately tied to the geometry of the
generalized quadrangle GQ with automorphism group the Weyl group
. The 27 charges correspond to the points and the 45 terms in the
entropy formula to the lines of GQ. Different truncations with
and 9 charges are represented by three distinguished subconfigurations of
GQ, well-known to finite geometers; these are the "doily" (i. e.
GQ) with 15, the "perp-set" of a point with 11, and the "grid" (i. e.
GQ) with 9 points, respectively. In order to obtain the correct signs
for the terms in the entropy formula, we use a non- commutative labelling for
the points of GQ. For the 40 different possible truncations with 9
charges this labelling yields 120 Mermin squares -- objects well-known from
studies concerning Bell-Kochen-Specker-like theorems. These results are
connected to our previous ones obtained for the symmetric entropy
formula in D=4 by observing that the structure of GQ is linked to a
particular kind of geometric hyperplane of the split Cayley hexagon of order
two, featuring 27 points located on 9 pairwise disjoint lines (a
distance-3-spread). We conjecture that the different possibilities of
describing the D=5 entropy formula using Jordan algebras, qubits and/or qutrits
correspond to employing different coordinates for an underlying non-commutative
geometric structure based on GQ.Comment: 17 pages, 3 figures, v2 a new paragraph added, typos correcte
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