184,472 research outputs found
Ligand-Specific Regulation of the Endogenous Mu-Opioid Receptor by Chronic Treatment with Mu-Opioid Peptide Agonist
No full textSince the discovery of the endomorphins (EM), the postulated endogenous peptide agonists of the mu-opioid receptors, several analogues have been synthesized to improve their binding and pharmacological profiles. We have shown previously that a new analogue, cis-1S,2R-aminocyclohexanecarboxylic acid2-endomorphin-2 (ACHC-EM2), had elevated mu-receptor affinity, selectivity, and proteolytic stability over the parent compound. In the present work, we have studied its antinociceptive effects and receptor regulatory processes. ACHC-EM2 displayed a somewhat higher (60%) acute antinociceptive response than the parent peptide, EM2 (45%), which peaked at 10 min after intracerebroventricular (icv) administration in the rat tail-flick test. Analgesic tolerance developed to the antinociceptive effect of ACHC-EM2 upon its repeated icv injection that was complete by a 10-day treatment. This was accompanied by attenuated coupling of mu-sites to G-proteins in subcellular fractions of rat brain. Also, the density of mu-receptors was upregulated by about 40% in the light membrane fraction, with no detectable changes in surface binding. Distinct receptor regulatory processes were noted in subcellular fractions of rat brains made tolerant by the prototypic full mu-agonist peptide, DAMGO, and its chloromethyl ketone derivative, DAMCK. These results are discussed in light of the recently discovered phenomenon, that is, the “so-called biased agonism” or “functional selectivity
Search for the rare decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-)
No full textA search for the decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-) is performed with 0.37 fb(-1) of pp collisions at root s = 7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are B(B-s(0) -> mu(+)mu(-)) mu(+)mu(-)) mu(+)mu(-)) mu(+)mu(-)) < 3.2 x 10(-9) at 95% confidence level
Strong Constraints on the Rare Decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-)
No full textA search for B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-) decays is performed using 1.0 fb(-1) of pp collision data collected at root s = 7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays, the number of observed events is consistent with expectation from background and standard model signal predictions. Upper limits on the branching fractions are determined to be B(B-s(0) -> mu(+)mu(-)) mu(+)mu(-)) < 1.0(0.81) x 10(-9) at 95% (90%) confidence level
Search for decays of B-0 -> e(+)e(-), B-0 -> mu(+)mu(-), B-0 -> e(+/-)mu(-/+)
No full textWe present a search for the decays B-0 -> e(+)e(-), B-0 ->mu(+)mu(-), and B-0 -> e(+/-)mu(-/+) in data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC B Factory. Using a data set of 111 fb(-1), we find no evidence for a signal in any of the three channels investigated and set the following branching fraction upper limits at the 90% confidence level: B(B-0 -> e(+)e(-))mu(+)mu(-)) e(+/-)mu(-/+))< 18x10(-8)
Search for B+ -> mu(+)nu(mu) and B+ -> mu N+ with inclusive tagging
No full textWe report the result for a search for the leptonic decay of B+ -> mu(+)nu mu using the full Belle dataset of 711 fb(-1) of integrated luminosity at the gamma(4S) resonance. In the Standard Model leptonic B-meson decays are helicity and Cabibbo-Kobayashi-Maskawa suppressed. To maximize sensitivity an inclusive tagging approach is used to reconstruct the second B meson produced in the collision. The directional information from this second B meson is used to boost the observed mu into the signal B-meson rest frame, in which the mu has a monochromatic momentum spectrum. Though its momentum is smeared by the experimental resolution, this technique improves the analysis sensitivity considerably. Analyzing the mu momentum spectrum in this frame we find B(B+ -> mu(+)nu mu)=(5.3 +/- 2.0 +/- 0.9) x 10(-7) with a one-sided significance of 2.8 standard deviations over the background-only hypothesis. This translates to a frequentist upper limit of B(B+ -> mu(+)nu mu) mu N+, but no evidence is observed for a sterile neutrino with a mass in a range of 01.5 GeV. The determined B+ -> mu(+)nu mu branching fraction limit is further used to constrain the mass and coupling space of the type II and type III two-Higgs-doublet models.LPH
Study of the rare B-s(0) and B-0 decays into the pi(+) pi(-) mu(+) mu(-) final state
No full textA search for the rare decays B-s(0) -> pi(+) pi-mu(+) mu-and B-0 -> pi(+) pi-mu(+) mu-is performed in a data set corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3GeV/c(2) and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B-s(0) -> pi(+) pi-mu(+) mu- and the first evidence of the decay B-0 -> pi(+) pi-mu(+) mu-are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(B-s(0) -> pi(+) pi-mu(+) mu(-)) =(8.6 +/- 1.5(stat) +/- 0.7(syst) +/- 0.7 (norm)) x 10(-8) and B(B-0 -> pi(+) pi-mu(+) mu(-)) =(2.11 +/- 0.51(stat) +/- 0.15(syst) +/- 0.16(norm)) x10(-8), where the third uncertainty is due to the branching fraction of the decay B-0. -> J/Psi(mu(+) mu(-)) K*(892)(0)(-> K+ pi(-)), used as a normalisation. (C) 2015 The Authors. Published by Elsevier B.V
Search for B-S(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-) decays
No full textA search for the rare decays B-S(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-) performed in pp collisions at root s = 7 TeV, with a data sample corresponding to an integrated luminosity of 5 fb(-1) collected by the CMS experiment at the LHC. In both decays, the number of events observed after all selection requirements is consistent with the expectation from background plus standard model signal predictions. The resulting upper limits on the branching fractions are B(B-S(0) -> mu(+)mu(-)) < 7.7 x 10(-9) and B(B-0 -> mu(+)mu(-) ) < 1.8 x 10(-9) at 95% confidence level
Search for the Decay B-S(0) -> Mu(+)mu(-) With the Atlas Detector
No full textA blind analysis searching for the decay B-s(0) -> mu(+)mu(-) has been performed using proton-proton collisions at a centre-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. With an integrated luminosity of 2.4 fb(-1) no excess of events over the background expectation is found and an upper limit is set on the branching fraction BR(B-s(0) -> mu(+)mu(-)) 2.2(1.9) x 10(-8) at 95% (90%) confidence level. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved
Search for the rare decays B+ -> mu(+)mu K–(+), B-0 -> mu(+)mu(-) K*(892)(0), and B-s(0) -> mu(+)mu(-)phi at CDF
No full textWe search for b –> s mu(+)mu(-) transitions in B meson (B+, B-0, or B-s(0)) decays with 924 pb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We find excesses with significances of 4.5, 2.9, and 2.4 standard deviations in the B+ –> mu(+)mu K–(+), B-0 –> mu(+)mu(-) K*(892)(0), and B-s(0) –> mu(+)mu(-)phi decay modes, respectively. Using B –> J/psi h (h = K+, K*(892)(0), phi) decays as normalization channels, we report branching fractions for the previously observed B+ and B-0 decays, B(B+ –> mu(+)mu K–(+)) = (0.59 +/- 0.15 +/- 0.04) x 10(-6), and B(B-0 –> mu(+)mu K-*(892)(0)) = (0.81 +/- 0.30 +/- 0.10) x 10(-6), where the first uncertainty is statistical, and the second is systematic. We set an upper limit on the relative branching fraction B(B-s(0) –> mu(+)mu(-)phi)/B(B-s(0) –> J/psi phi) < 2.6(2.3) x 10(-3) at the 95(90)% confidence level, which is the most stringent to date
Search for the rare decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-)
No full textA search for the decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-) is performed with 0.37 fb(-1) of pp collisions at root s = 7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are B(B-s(0) -> mu(+)mu(-)) mu(+)mu(-)) mu(+)mu(-)) mu(+)mu(-)) < 3.2 x 10(-9) at 95% confidence level. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved
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