1,118 research outputs found
Colony-stimulating factor 1 receptor blockade prevents fractionated whole-brain irradiation-induced memory deficits
Background: Primary central nervous system (CNS) neoplasms and brain metastases are routinely treated with whole-brain radiation. Long-term survival occurs in many patients, but their quality of life is severely affected by the development of cognitive deficits, and there is no treatment to prevent these adverse effects. Neuroinflammation, associated with activation of brain-resident microglia and infiltrating monocytes, plays a pivotal role in loss of neurological function and has been shown to be associated with acute and long-term effects of brain irradiation. Colony-stimulating factor 1 receptor (CSF-1R) signaling is essential for the survival and differentiation of microglia and monocytes. Here, we tested the effects of CSF-1R blockade by PLX5622 on cognitive function in mice treated with three fractions of 3.3 Gy whole-brain irradiation. Methods: Young adult C57BL/6J mice were given three fractions of 3.3 Gy whole-brain irradiation while they were on diet supplemented with PLX5622, and the effects on periphery monocyte accumulation, microglia numbers, and neuronal functions were assessed. Results: The mice developed hippocampal-dependent cognitive deficits at 1 and 3 months after they received fractionated whole-brain irradiation. The impaired cognitive function correlated with increased number of periphery monocyte accumulation in the CNS and decreased dendritic spine density in hippocampal granule neurons. PLX5622 treatment caused temporary reduction of microglia numbers, inhibited monocyte accumulation in the brain, and prevented radiation-induced cognitive deficits. Conclusions: Blockade of CSF-1R by PLX5622 prevents fractionated whole-brain irradiation-induced memory deficits. Therapeutic targeting of CSF-1R may provide a new avenue for protection from radiation-induced memory deficits
Search for anomalous top-gluon couplings at LHC revisited
Through top-quark pair productions at LHC, we study possible effects of
nonstandard top-gluon couplings yielded by SU(3)xSU(2)xU(1) invariant
dimension-6 effective operators. We calculate the total cross section and also
some distributions for p p -> t tbar X as functions of two anomalous-coupling
parameters, i.e., the chromoelectric and chromomagnetic moments of the top,
which are constrained by the total cross section sigma(p pbar -> t tbar X)
measured at Tevatron. We find that LHC might give us some chances to observe
sizable effects induced by those new couplings.Comment: One comment and related two refs. added. Final version (to appear in
Eur.Phys.J. C
A Kinesin-5, Cin8, Recruits Protein Phosphatase 1 to Kinetochores and Regulates Chromosome Segregation
Kinesin-5 is a highly conserved homo-tetrameric protein complex responsible for crosslinking microtubules and pushing spindle poles apart. The budding yeast Kinesin-5, Cin8, is highly concentrated at kinetochores in mitosis before anaphase, but its functions there are largely unsolved. Here, we show that Cin8 localizes to kinetochores in a cell-cycle-dependent manner and concentrates near the microtubule binding domains of Ndc80 at metaphase. Cin8’s kinetochore localization depends on the Ndc80 complex, kinetochore microtubules, and the Dam1 complex. Consistent with its kinetochore localization, a Cin8 deletion induces a loss of tension at the Ndc80 microtubule binding domains and a major delay in mitotic progression. Cin8 associates with Protein Phosphatase 1 (PP1), and mutants that inhibit its PP1 binding also induce a loss of tension at the Ndc80 microtubule binding domains and delay mitotic progression. Taken together, our results suggest that Cin8-PP1 plays a critical role at kinetochores to promote accurate chromosome segregation by controlling Ndc80 attachment to microtubules. Suzuki, Gupta, et al. report that a Kinesin-5, Cin8, binds Protein Phosphatase 1 (PP1) and localizes near the Ndc80 complex. A Cin8 mutant lacking PP1 binding induces a mitotic delay and loss of tension at Ndc80, suggesting a critical role for Cin8-PP1 in promoting chromosome segregation by controlling Ndc80 attachment to microtubules
Analysis of the vector and axialvector mesons with QCD sum rules
In this article, we study the vector and axialvector mesons with the
QCD sum rules, and make reasonable predictions for the masses and decay
constants, then calculate the leptonic decay widths. The present predictions
for the masses and decay constants can be confronted with the experimental data
in the future. We can also take the masses and decay constants as basic input
parameters and study other phenomenological quantities with the three-point
vacuum correlation functions via the QCD sum rules.Comment: 14 pages, 16 figure
Calculations of binding energies and masses of heavy quarkonia using renormalon cancellation
We use various methods of Borel integration to calculate the binding ground
energies and masses of b-bbar and t-tbar quarkonia. The methods take into
account the leading infrared renormalon structure of the hard+soft part of the
binding energies E(s), and of the corresponding quark pole masses m_q, where
the contributions of these singularities in M(s) = 2 m_q + E(s) cancel.
Beforehand, we carry out the separation of the binding energy into its
hard+soft and ultrasoft parts. The resummation formalisms are applied to
expansions of m_q and E(s) in terms of quantities which do not involve
renormalon ambiguity, such as MSbar quark mass, and alpha_s. The
renormalization scales are different in calculations of m_q, E(s) and E(us).
The MSbar mass of b quark is extracted, and the binding energies of t-tbar and
the peak (resonance) energies for (t+tbar) production are obtained.Comment: 23 pages, 8 double figures, revtex4; the version to appear in
Phys.Rev.D; extended discussion between Eqs.(25) and (26); the paragraph
between Eqs.(32) and (33) is new and explains the numerical dependence of the
residue parameter on the factorization scale; several new references were
added; acknowledgments were modified; the numerical results are unchange
A High Statistics Search for Ultra-High Energy Gamma-Ray Emission from Cygnus X-3 and Hercules X-1
We have carried out a high statistics (2 Billion events) search for
ultra-high energy gamma-ray emission from the X-ray binary sources Cygnus X-3
and Hercules X-1. Using data taken with the CASA-MIA detector over a five year
period (1990-1995), we find no evidence for steady emission from either source
at energies above 115 TeV. The derived upper limits on such emission are more
than two orders of magnitude lower than earlier claimed detections. We also
find no evidence for neutral particle or gamma-ray emission from either source
on time scales of one day and 0.5 hr. For Cygnus X-3, there is no evidence for
emission correlated with the 4.8 hr X-ray periodicity or with the occurrence of
large radio flares. Unless one postulates that these sources were very active
earlier and are now dormant, the limits presented here put into question the
earlier results, and highlight the difficulties that possible future
experiments will have in detecting gamma-ray signals at ultra-high energies.Comment: 26 LaTeX pages, 16 PostScript figures, uses psfig.sty to be published
in Physical Review
GMRT 610 MHz observations of galaxy clusters in the ACT equatorial sample
Large scale structure and cosmolog
Measurement of the Atmospheric Muon Spectrum from 20 to 3000 GeV
The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3
magnetic muon spectrometer for zenith angles ranging from 0 degree to 58
degree. Due to the large exposure of about 150 m2 sr d, and the excellent
momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in
the vertical direction is achieved.
The ratio of positive to negative muons is studied between 20 GeV and 500
GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003
(stat.) +- 0.019 (syst.).Comment: Total 32 pages, 9Figure
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
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