5,535 research outputs found
Mitochondrial potassium channel opener diazoxide preserves neuronal-vascular function after cerebral ischemia in newborn pigs
Background and Purpose-N-Methyl-D-aspartate (NMDA) elicits neuronally mediated cerebral arteriolar vasodilation that is reduced by ischemia/reperfusion (I/R). This sequence has been preserved by pretreatment with the ATP-sensitive potassium (K-ATP) channel opener aprikalim, although the mechanism was unclear. In the heart, mitochondrial K-ATP channels (mitoK(ATP)) are involved in the ischemic preconditioning-like effect of K+ channel openers. We determined whether the selective mitoK(ATP) channel opener diazoxide preserves the vascular dilation to NMDA after I/R.
Methods-Pial arteriolar diameters were determined with the use of closed cranial window/intravital microscopy in anesthetized piglets. Vascular responses to NMDA were assessed before and 1 hour after 10 minutes of global cerebral ischemia induced by raising intracranial pressure. Subgroups received 1 of the following pretreatments before I/R: vehicle; 1 to 10 mu mol/L diazoxide; and coapplication of 100 mu mol/L 5-hydroxydecanoic acid (5-HD), a K-ATP antagonist with diazoxide.
Results-NMDA-induced dose-dependent pial arteriolar dilation was not affected by diazoxide treatment only but was severely attenuated by I/R, In contrast, diazoxide dose-dependently preserved the NMDA vascular response after I/R; at 10 mu mol/L, diazoxide arteriolar responses were unaltered by I/R. The effect of diazoxide was antagonized by coapplication of 5-HD with diazoxide. Percent preservation of 100 mu mol/L NMDA-induced vasodilation after I/R was 53 +/- 19% (mean +/- SEM, n = 8) in vehicle-treated controls versus 55 +/- 10%, 85 +/- 5%, and 99 +/- 15% in animals pretreated with 1, 5, and 10 mu mol/L diazoxide (n = 8, n = 8, and n = 12, respectively) and 60 +/- 15% in the group treated with 5-HD+diazoxide (n = 5).
Conclusions-The mitoK(ATP) channel opener diazoxide in vivo preserves neuronal function after I/R, shown by pial arteriolar responses to NMDA, in a dose-dependent manner. Thus, activation of mitoK(ATP) channels may play a role in mediating the protective effect of other K+ channel openers
Diffractive Higgs Production from Intrinsic Heavy Flavors in the Proton
We propose a novel mechanism for exclusive diffractive Higgs production in which the Higgs boson carries a significant fraction of the
projectile proton momentum. This mechanism will provide a clear experimental
signal for Higgs production due to the small background in this kinematic
region. The key assumption underlying our analysis is the presence of intrinsic
heavy flavor components of the proton bound state, whose existence at high
light-cone momentum fraction has growing experimental and theoretical
support. We also discuss the implications of this picture for exclusive
diffractive quarkonium and other channels.Comment: 30 pages, 5 figure
You're the Coach: A Guide for Parents of New Drivers, December 8, 2015
This publication is a guide for parents and guardians of teenagers learning to drive. It should be used with the Iowa Driver’s Manual to aid you in instructing your new driver about how to safely and responsibly operate a motor vehicle. Since the task of driving is affected by changing conditions, this manual does not attempt to cover all situations that may arise
Non-thermal leptogenesis with strongly hierarchical right handed neutrinos
Assuming the Dirac-type neutrino masses m_D are related to quark or charged
lepton masses, neutrino oscillation data indicate that right handed neutrino
masses are in general strongly hierarchical. In particular, if m_D is similar
to the up-type quark masses, the mass of the lightest right handed neutrino
M_1<~10^6 GeV. We show that non-thermal leptogenesis by inflaton decay can
yield sufficient baryon asymmetry despite this constraint, and discuss how the
asymmetry is correlated with the low energy neutrino masses and CP-violating
phases.Comment: 7 pages, 5 figures. v2: added some comments and references, v3: minor
corrections and additions, v4: a typo corrected, published versio
Effective Universal Unrestricted Adversarial Attacks using a MOE Approach
Recent studies have shown that Deep Leaning models are susceptible to
adversarial examples, which are data, in general images, intentionally modified
to fool a machine learning classifier. In this paper, we present a
multi-objective nested evolutionary algorithm to generate universal
unrestricted adversarial examples in a black-box scenario. The unrestricted
attacks are performed through the application of well-known image filters that
are available in several image processing libraries, modern cameras, and mobile
applications. The multi-objective optimization takes into account not only the
attack success rate but also the detection rate. Experimental results showed
that this approach is able to create a sequence of filters capable of
generating very effective and undetectable attacks
Exclusive and semi-inclusive strangeness and charm production in and reactions
Using the Quark-Gluon Strings Model (QGSM) combined with Regge phenomenology
we consider the reactions and which are dominated by the contributions of the and
Regge trajectories, respectively. The spin structure of the amplitudes is
described by introducing Reggeized Born terms. It is found that the existing
data for the reaction are in reasonable agreement
with the model predictions. To describe the absolute values of the cross
sections it is necessary to introduce also suppression factors which can be
related to absorption corrections. Furthermore, assuming the SU(4) symmetry to
hold for Regge residues and the universality of absorption corrections we
calculate the cross section of the reaction .
Employing the latter results from reactions we then estimate the
contributions of the pion exchange mechanism to the cross sections of the
reactions and and compare them
with the contributions of the and exchanges. We find that the
reactions are dominated not by pion exchange but by and exchanges,
respectively. Moreover, assuming the SU(4) symmetry to hold approximately for
the coupling constants = we analyze also
the production of leading hyperons in the reaction . It is shown that the non-perturbative mechanism should give an
essential contribution to the yield for .Comment: 3 pages, LaTeX, 4 postscript figures; contribution to QNP2002,
Juelich, June 10-14, 200
Hiding relativistic degrees of freedom in the early universe
We quantify the extent to which extra relativistic energy density can be
concealed by a neutrino asymmetry without conflicting with the baryon asymmetry
measured by the Wilkinson Microwave Anisotropy Probe (WMAP). In the presence of
a large electron neutrino asymmetry, slightly more than seven effective
neutrinos are allowed by Big Bang Nucleosynthesis (BBN) and WMAP at 2\sigma.
The same electron neutrino degeneracy that reconciles the BBN prediction for
the primordial helium abundance with the observationally inferred value also
reconciles the LSND neutrino with BBN by suppressing its thermalization prior
to BBN.Comment: 5 pages, 5 figure
Unenhanced helical CT of ureterolithiasis: incidence of secondary urinary tract findings
Objective: To determine the incidence of secondary signs of obstruction in patients with ureteral stones on unenhanced helical CT scans.MATERIAL AND Methods: Three hundred consecutive patients with suspected renal colic referred by the emergency department for an unenhanced helical CT scan were evaluated. One hundred and thirty two patients with ureteric calculi were viewed prospectively for the secondary signs of obstruction, which include hydronephrosis, hydroureter, perinephric stranding, nephromegaly, periureteral edema and difference in attenuation between acutely obstructed kidney and unobstructed kidney.Results: In the evaluated 132 patients, calculi were present in the proximal, mid and distal ureter in 12, 18 and 112 patients respectively. Four patients had a contralateral ureteric calculus while none had more than one ureteric calculus on the same site. Concurrent renal parenchymal calculi were seen in 40 patients with ureteric stones, hydronephrosis in 69, hydroureter in 93 and perinephric strandings in 66 patients. Nephromegaly was seen in 15 and periureteral edema in 42 patients. In 87% patients with acute renal obstruction, the affected kidney was less dense than the unobstructed kidney. Only 5 of 132 patients had no associated findings.CONCLUSION: Unenhanced helical CT has rapidly become the imaging technique of choice in evaluating patients with acute ureteric colic. The secondary signs of obstruction provide supportive evidence of acute obstructive process
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