598 research outputs found

    Modulation of Antimalarial Activity at a Putative Bisquinoline Receptor in vivo Using Fluorinated Bisquinolines

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    Antimalarials can interact with heme covalently, by - interactions or hydrogen bonding. Consequently, the prototropy of 4-aminoquinolines and quinoline methanols was investigated using quantum mechanics. Calculations showed mefloquine protonated preferentially at the piperidine and was impeded at the endocyclic nitrogen due to electronic rather than steric factors. In gas phase calculations, 7-substituted mono- and bis-4-aminoquinolines were preferentially protonated at the endocyclic quinoline nitrogen. By contrast, compounds with a trifluoromethyl substituent on both the 2- and 8-positions, reversed the order of protonation which now favored the exocyclic secondary amine nitrogen at the 4-position. Loss of antimalarial efficacy by CF3 groups simultaneously occupying the 2- and 8-positions was recovered if the CF3 group occupied the 7-position. Hence, trifluromethyl groups buttressing quinolinyl nitrogen shifted binding of antimalarials to hematin, enabling switching from endocyclic to the exocyclic N. Both theoretical calculations (DFT calculations: B3LYP/6- 31+G*) and crystal structure of (±)-trans-N1,N2-bis-(2,8-ditrifluoromethylquinolin-4- yl)cyclohexane-1,2-diamine were used to reveal preferred mode(s) of interaction with hematin. The order of antimalarial activity in vivo followed the capacity for a redox change of the iron(III)state which has important implications for the future rational design of 4- aminoquinoline antimalarials

    Synthesis, Structural Determination, and Pharmacology of Putative Dinitroaniline Antimalarials

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    A series of novel, homologous compounds possessing the general formula N1‐Nn‐bis(2,6‐dinitro‐4‐trifluormethylphenyl)‐1,n‐diamino alkanes (where n=4, 6, 10 or 12), were designed to probe inter‐ and intra‐ binding site dimensions in malarial parasite (Plasmodium) tubulin. Various crystal structures, including chloralin and trifluralin, an isopropyl dimer, and 2,6‐dinitro‐4‐trifluoromethyl‐phenylamine, were determined. Dinitroanilines, when soluble, were evaluated both in culture and in vivo. Trifluralin was up to 2‐fold more active than chloralin against cultured parasites. The isopropyl dimer was water soluble (>5 mM) and revealed activity superior to that of chloralin in culture. The effects of selected dinitroanilines upon the mitotic microtubular structures of Plasmodium, the putative target of these dinitroanilines, were also determined. Electronic properties of the molecules were calculated using DFT (B3LYP/6‐31+G* level) to ascertain whether incorporation of such a pharmacophore could allow both QSAR and rational development of more selectively toxic antiparasitic agents

    Purpurogallin-A heme binding component of oak galls

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    Recently, it has been shown that Purpurogallin (PPG), an orange benztropolone constituent of oak galls and its derivative, CU-CPT22, can compete with the binding of the specific lipoprotein ligand to toll-like receptors (TLRs), which are type I transmembrane proteins. These recognize pathogen-derived macromolecules that play a key role in the innate immune system. This system provides an attractive target for the treatment of various immune disorders. Notably, PPG also interacts with various metals and its mode of action against HIV in vitro may involve inhibition of metal containing integrases. In the current study, an optimised synthesis of PPG is presented together with its gas phase behaviour (probed by mass spectrometry) as well as its redox behaviour with porphyrins such as heme. This interaction may also explain its effects at metal containing integrases within HIV in vitro as well as its action during processing of iron complexes within Plasmodia. This compound could serve as a novel prototype for the synthesis of novel redox active antimalarials

    A search for the decay modes B+/- to h+/- tau l

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    We present a search for the lepton flavor violating decay modes B+/- to h+/- tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472 million BBbar pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the tau four-momentum. The resulting tau candidate mass is our main discriminant against combinatorial background. We see no evidence for B+/- to h+/- tau l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.

    Evidence for an excess of B -> D(*) Tau Nu decays

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    Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.Comment: Expanded section on systematics, text corrections, improved the format of Figure 2 and included the effect of the change of the Tau polarization due to the charged Higg

    Search for the decay modes D^0 → e^+e^-, D^0 → ÎŒ^+ÎŒ^-, and D^0 → e^±Ό∓

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    We present searches for the rare decay modes D^0→e^+e^-, D^0→Ό^+ÎŒ^-, and D^0→e^±Ό^∓ in continuum e^+e^-→cc events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468  fb^(-1). These decays are highly Glashow–Iliopoulos–Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D^0→Ό^+ÎŒ^- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman–Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D^0→e^+e^-)<1.7×10^(-7), B(D^0→Ό^+ÎŒ^-) within [0.6,8.1]×10^(-7), and B(D^0→e^±Ό^∓)<3.3×10^(-7)

    Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

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    This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of √s = 7 TeV;{\rm Te}{\rm V}andcorrespondtoanintegratedluminosityof and correspond to an integrated luminosity of 4.6\;{\rm f}{{{\rm b}}^{-1}}.ThemeasurementisperformedbyreconstructingtheboostedWorZbosonsinsinglejets.ThereconstructedjetmassisusedtoidentifytheWandZbosons,andajetsubstructuremethodbasedonenergyclusterinformationinthejetcentre−of−massframeisusedtosuppressthelargemulti−jetbackground.Thecross−sectionforeventswithahadronicallydecayingWorZboson,withtransversemomentum. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum {{p}_{{\rm T}}}\gt 320\;{\rm Ge}{\rm V}andpseudorapidity and pseudorapidity |\eta |\lt 1.9,ismeasuredtobe, is measured to be {{\sigma }_{W+Z}}=8.5\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques

    Study of the reaction e^{+}e^{-} -->J/psi\pi^{+}\pi^{-} via initial-state radiation at BaBar

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    We study the process e+e−→J/ψπ+π−e^+e^-\to J/\psi\pi^{+}\pi^{-} with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BaBar detector at center-of-mass energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454 fb−1\mathrm{fb^{-1}}. We investigate the J/ψπ+π−J/\psi \pi^{+}\pi^{-} mass distribution in the region from 3.5 to 5.5 GeV/c2\mathrm{GeV/c^{2}}. Below 3.7 GeV/c2\mathrm{GeV/c^{2}} the ψ(2S)\psi(2S) signal dominates, and above 4 GeV/c2\mathrm{GeV/c^{2}} there is a significant peak due to the Y(4260). A fit to the data in the range 3.74 -- 5.50 GeV/c2\mathrm{GeV/c^{2}} yields a mass value 4244±54244 \pm 5 (stat) ±4 \pm 4 (syst)MeV/c2\mathrm{MeV/c^{2}} and a width value 114−15+16114 ^{+16}_{-15} (stat)±7 \pm 7(syst)MeV\mathrm{MeV} for this state. We do not confirm the report from the Belle collaboration of a broad structure at 4.01 GeV/c2\mathrm{GeV/c^{2}}. In addition, we investigate the π+π−\pi^{+}\pi^{-} system which results from Y(4260) decay

    Observation and study of baryonic B decays: B -> D(*) p pbar, D(*) p pbar pi, and D(*) p pbar pi pi

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    We present a study of ten B-meson decays to a D(*), a proton-antiproton pair, and a system of up to two pions using BaBar's data set of 455x10^6 BBbar pairs. Four of the modes (B0bar -> D0 p anti-p, B0bar -> D*0 p anti-p, B0bar -> D+ p anti-p pi-, B0bar -> D*+ p anti-p pi-) are studied with improved statistics compared to previous measurements; six of the modes (B- -> D0 p anti-p pi-, B- -> D*0 p anti-p pi-, B0bar -> D0 p anti-p pi- pi+, B0bar -> D*0 p anti-p pi- pi+, B- -> D+ p anti-p pi- pi-, B- -> D*+ p anti-p pi- pi-) are first observations. The branching fractions for 3- and 5-body decays are suppressed compared to 4-body decays. Kinematic distributions for 3-body decays show non-overlapping threshold enhancements in m(p anti-p) and m(D(*)0 p) in the Dalitz plots. For 4-body decays, m(p pi-) mass projections show a narrow peak with mass and full width of (1497.4 +- 3.0 +- 0.9) MeV/c2, and (47 +- 12 +- 4) MeV/c2, respectively, where the first (second) errors are statistical (systematic). For 5-body decays, mass projections are similar to phase space expectations. All results are preliminary.Comment: 28 pages, 90 postscript figures, submitted to LP0

    Observation of associated near-side and away-side long-range correlations in √sNN=5.02  TeV proton-lead collisions with the ATLAS detector

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    Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  Όb-1 of data as a function of transverse momentum (pT) and the transverse energy (ÎŁETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∌0) correlation that grows rapidly with increasing ÎŁETPb. A long-range “away-side” (Δϕ∌π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ÎŁETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ÎŁETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁥2Δϕ modulation for all ÎŁETPb ranges and particle pT
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