126 research outputs found
Сравнительный анализ экспериментальной фармакокинетики новых нейротропных пептидных лекарственных средств
Experimental pharmacokinetics of new pharmacologically active peptides, modified analogues of endogenous neuropeptides, has been investigated in rats and rabbits. The study icluded 3 new drugs: (i) the nootropic drug noopept (phenylacetyl-prolyl-glycine ethyl ester); (ii) dilept (N-caproyl-L-prolyl-L-tyrosine methyl ester) – the antipsychotic with positive mnemotropic action; (iii) compound GB-115 – selective anxiolytic (phenylhexanoyl-prolyl-tryptophan amide). Differences in pharmacokinetics and biotransformation of the studied drugs depended on their structural features. The ether derivatives noopept and dilept underwent intensive metabolism by rat gastrointestinal esterases and peptidases with the formation of active metabolites. Being an amide, the compound GB-115 was more resistant to the enzymatic effects of peptidases and was detected for a longer period in the blood of experimental animals. In rabbits the studied compounds were less exposed to the enzymatic action by gastrointestinal peptidases, and were detected plasma of rabbits for a longer period. The higher stability of the compounds studied in rabbits may be attributed not only to the structural features of the studied dipeptides, but also to differences in the activity of the enzymatic systems of the gastrointestinal tract participating in their metabolism, as well as differences in the rate of hepatic and renal blood flow in rats and rabbits.Приведены результаты изучения сравнительной экспериментальной фармакокинетики и метаболизма новых фармакологически активных лекарственных средств (ЛС) пептидной природы у животных 2 видов (крысы, кролики). Объектами исследований были 3 новых ЛС: (i) ноотропный препарат ноопепт – этиловый эфир фенилацетил-пролил-глицина; (ii) антипсихотик с положительным мнемотропным действием дилепт – метиловый эфир N-капроил-L-пролил-L-тирозина; (iii) селективный анксиолитик – соединение ГБ-115 – амид фенилгексаноил-пролил-триптофана. Установлены различия фармакокинетики и биотрансформации изучаемых ЛС в зависимости от структурных особенностей субстанций этих соединений. Установлено, что эфирные производные ноопепт и дилепт подвергаются интенсивному метаболизму в организме крыс под влиянием эстераз и пептидаз ЖКТ с образованием активных метаболитов. Соединение ГБ-115, являющееся амидом, более устойчиво к энзиматическому воздействию пептидаз и более продолжительное время определяется в крови экспериментальных животных в неизмененном виде. В организме кроликов изучаемые соединения в меньшей степени подвергаются энзиматическому воздействию со стороны пептидаз ЖКТ и более продолжительное время определяются в плазме крови этих животных в неизмененном виде, что связано не только со структурными особенностями изучаемых дипептидов, но и различиями активности энзиматических систем ЖКТ, принимающих участие в их метаболизме, а также с различиями в скорости печеночного и почечного кровотока у крыс и кроликов
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Identification of beauty and charm quark jets at LHCb
Identification of jets originating from beauty and charm quarks is important
for measuring Standard Model processes and for searching for new physics. The
performance of algorithms developed to select - and -quark jets is
measured using data recorded by LHCb from proton-proton collisions at
TeV in 2011 and at TeV in 2012. The efficiency for
identifying a jet is about 65%(25%) with a probability for
misidentifying a light-parton jet of 0.3% for jets with transverse momentum
GeV and pseudorapidity . The dependence of
the performance on the and of the jet is also measured
Search for B⁺c decays to the pp‾π⁺ final state
A search for the decays of the B + c meson to pp-π + is performed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb -1 collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV. No signal is found and an upper limit, at 95% confidence level, is set, fcfu×B(B + c →ppπ + ) < 3.6×10-8 in the kinematic region m(pp) < 2.85 GeV/c2, p T (B) < 20 GeV/c and 2.0 < y(B) < 4.5, where B is the branching fraction and f c (f u ) is the fragmentation fraction of the b quark into a B c + (B + ) meson
Measurement of CP observables in B± → D(⁎)K± and B± → D(⁎)π± decays
Measurements of CP observables in B ± →D (⁎) K ± and B ± →D (⁎) π ± decays are presented, where D (⁎) indicates a neutral D or D ⁎ meson that is an admixture of D (⁎)0 and D¯ (⁎)0 states. Decays of the D ⁎ meson to the Dπ 0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K ± π ∓ , K + K − and π + π − final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb −1 taken at centre-of-mass energies of s=7, 8 and 13 TeV, respectively. The study of B ± →D ⁎ K ± and B ± →D ⁎ π ± decays using a partial reconstruction method is the first of its kind, while the measurement of B ± →DK ± and B ± →Dπ ± decays is an update of previous LHCb measurements. The B ± →DK ± results are the most precise to date
Observation of the B0 → ρ0ρ0 decay from an amplitude analysis of B0 → (π+π−)(π+π−) decays
Proton–proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to
an integrated luminosity of 3.0 fb−1, are analysed to search for the charmless B0 → ρ0ρ0 decay.
More than 600 B0 → (π+π−)(π+π−) signal decays are selected and used to perform an amplitude
analysis, under the assumption of no CP violation in the decay, from which the B0 → ρ0ρ0 decay is
observed for the first time with 7.1 standard deviations significance. The fraction of B0 → ρ0ρ0 decays
yielding a longitudinally polarised final state is measured to be fL = 0.745+0.048
−0.058(stat) ± 0.034(syst).
The B0 → ρ0ρ0 branching fraction, using the B0 → φK∗(892)0 decay as reference, is also reported as
B(B0 → ρ0ρ0) = (0.94 ± 0.17(stat) ± 0.09(syst) ± 0.06(BF)) × 10−6
Measurement of the CP-violating phase β in B0 → J/ψπ+π− decays and limits on penguin effects
Time-dependent CP violation is measured in the (—)
B 0 → J/ψπ+π− channel for each π+π− resonant
final state using data collected with an integrated luminosity of 3.0 fb−1 in pp collisions using the LHCb
detector. The final state with the largest rate, J/ψρ0(770), is used to measure the CP-violating angle
2βeff to be (41.7 ± 9.6+2.8
−6.3)◦. This result can be used to limit the size of penguin amplitude contributions
to CP violation measurements in, for example, (—)
B 0
s → J/ψφ decays. Assuming approximate SU(3) flavour
symmetry and neglecting higher order diagrams, the shift in the CP-violating phase φs is limited to be
within the interval [−1.05◦,+1.18◦] at 95% confidence level. Changes to the limit due to SU(3) symmetry
breaking effects are also discussed
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