2,463 research outputs found
RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation
Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A2 (cPLA2), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA2. Inhibition of RhoA, Rho kinase and cPLA2 significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA2 activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA2. The immunofluorescence staining showed that ROCK1 or ROCK2, two isoforms of Rho kinase, was co-localized with cPLA2 in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK1 or ROCK2 bonded directly with cPLA2 and phospho-cPLA2. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA2 activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA2 activation
ASTROD and ASTROD I -- Overview and Progress
In this paper, we present an overview of ASTROD (Astrodynamical Space Test of
Relativity using Optical Devices) and ASTROD I mission concepts and studies.
The missions employ deep-space laser ranging using drag-free spacecraft to map
the gravitational field in the solar-system. The solar-system gravitational
field is determined by three factors: the dynamic distribution of matter in the
solar system; the dynamic distribution of matter outside the solar system
(galactic, cosmological, etc.) and gravitational waves propagating through the
solar system. Different relativistic theories of gravity make different
predictions of the solar-system gravitational field. Hence, precise
measurements of the solar-system gravitational field test all these. The tests
and observations include: (i) a precise determination of the relativistic
parameters beta and gamma with 3-5 orders of magnitude improvement over
previous measurements; (ii) a 1-2 order of magnitude improvement in the
measurement of G-dot; (iii) a precise determination of any anomalous, constant
acceleration Aa directed towards the Sun; (iv) a measurement of solar angular
momentum via the Lense-Thirring effect; (v) the detection of solar g-mode
oscillations via their changing gravity field, thus, providing a new eye to see
inside the Sun; (vi) precise determination of the planetary orbit elements and
masses; (viii) better determination of the orbits and masses of major
asteroids; (ix) detection and observation of gravitational waves from massive
black holes and galactic binary stars in the frequency range 0.05 mHz to 5 mHz;
and (x) exploring background gravitational-waves.Comment: 17 pages, 6 figures, presented to The Third International ASTROD
Symposium on Laser Astrodynamics, Space Test of Relativity and
Gravitational-Wave Astronomy, Beijing, July 14-16, 2006; International
Journal of Modern Physics D, in press (2008
CS Lines Profiles in Hot Cores
We present a theoretical study of CS line profiles in archetypal hot cores.
We provide estimates of line fluxes from the CS(1-0) to the CS(15-14)
transitions and present the temporal variation of these fluxes. We find that
\textit{i)} the CS(1-0) transition is a better tracer of the Envelope of the
hot core whereas the higher-J CS lines trace the ultra-compact core;
\textit{ii)} the peak temperature of the CS transitions is a good indicator of
the temperature inside the hot core; \textit{iii)} in the Envelope, the older
the hot core the stronger the self-absorption of CS; \textit{iv)} the
fractional abundance of CS is highest in the innermost parts of the
ultra-compact core, confirming the CS molecule as one of the best tracers of
very dense gas.Comment: 17 pages, 5 figures, 1 table, In press in Ap
First Acetic Acid Survey with CARMA in Hot Molecular Cores
Acetic acid (CHCOOH) has been detected mainly in hot molecular cores
where the distribution between oxygen (O) and nitrogen (N) containing molecular
species is co-spatial within the telescope beam. Previous work has presumed
that similar cores with co-spatial O and N species may be an indicator for
detecting acetic acid. However, does this presumption hold as higher spatial
resolution observations become available of large O and N-containing molecules?
As the number of detected acetic acid sources is still low, more observations
are needed to support this postulate. In this paper, we report the first acetic
acid survey conducted with the Combined Array for Research in Millimeter-wave
Astronomy (CARMA) at 3 mm wavelengths towards G19.61-0.23, G29.96-0.02 and IRAS
16293-2422. We have successfully detected CHCOOH via two transitions toward
G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A.
The determined column density of CHCOOH is 2.0(1.0)
cm and the abundance ratio of CHCOOH to methyl formate (HCOOCH)
is 2.2(0.1) toward G19.61-0.23. Toward IRAS 16293 A, the
determined column density of CHCOOH is 1.6
cm and the abundance ratio of CHCOOH to methyl formate (HCOOCH)
is 1.0 both of which are consistent with abundance
ratios determined toward other hot cores. Finally, we model all known line
emission in our passband to determine physical conditions in the regions and
introduce a new metric to better reveal weak spectral features that are blended
with stronger lines or that may be near the 1-2 detection limit.Comment: 28 pages, 8 figures, accepted for publication in the ApJ; Revised
citation in session 2, references remove
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Market Orientation, Growth Strategy, and Firm Performance: The Moderating Effects of External Connections
This study examines the mediating effect of growth strategy (including market and product expansion strategies) on the linkage of market orientation (MO) to firm performance and the moderating effects of a firm's external connections (including political and business ties) on the relationship between MO and growth strategy. It finds that both market and product expansion strategies are key conduits through which MO improves firm performance. In addition, the relationship between MO and market expansion strategy is positively moderated by political ties but negatively moderated by business ties, while the linkage of MO to product expansion strategy is moderated negatively by political ties but positively by business ties. By combining mediating and moderating effects in a framework that integrates MO, growth strategy, external connections, and firm performance, this study enriches our knowledge on the implications of MO and provides insight into factors that facilitate firm growth
A procedure for the analysis of site‐specific and structure‐specific fucosylation in alpha‐1‐antitrypsin
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134210/1/elps5934.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134210/2/elps5934_am.pd
Large-Format X-Ray Pinhole Camera
National Security Technologies, LLC, has successfully implemented many scientific and engineering innovations in the new Large-Format Pinhole Camera (LFPHC), which have dramatically increased the detection sensitivity and reliability of the camera in exotic locations, such as the Sandia National Laboratories Z-facility. Quality improvements of the LFPHC have been demonstrated in its fielding at Z, where high-quality images were recorded. A major improvement was the development of a new, user-friendly LFPHC camera back that would tolerate high radiation, electromagnetic interference, and mechanical shock. Key modifications resulted in improved detection sensitivity, spatial resolution, uniformity along the microchannel plate strip, and stability of the interframe timing and delay. Design considerations and improvements will be discussed
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