476 research outputs found
A strategy for enrichment of claudins based on their affinity to Clostridium perfringens enterotoxin
<p>Abstract</p> <p>Background</p> <p>Claudins, a family of protein localized in tight junctions, are essential for the control of paracellular permeation in epithelia and endothelia. The interaction of several claudins with <it>Clostridium perfringens </it>enterotoxin (CPE) has been exploited for an affinity-based enrichment of CPE-binding claudins from lysates of normal rat cholangiocytes.</p> <p>Results</p> <p>Immunoblotting and mass spectrometry (MS) experiments demonstrate strong enrichment of the CPE-binding claudins -3, -4 and -7, indicating specific association with glutathione-S-transferase (GST)-CPE<sub>116–319 </sub>fusion protein. In parallel, the co-elution of (non-CPE-binding) claudin-1 and claudin-5 was observed. The complete set of co-enriched proteins was identified by MS after electrophoretic separation. Relative mass spectrometric protein quantification with stable isotope labeling with amino acids in cell culture (SILAC) made it possible to discriminate specific binding from non-specific association to GST and/or matrix material.</p> <p>Conclusion</p> <p>CPE<sub>116–319 </sub>provides an efficient tool for single step enrichment of different claudins from cell lysates. Numerous proteins were shown to be co-enriched with the CPE-binding claudins, but there are no indications (except for claudins -1 and -5) for an association with tight junctions.</p
First measurement of the 14N(p,gamma)15O cross section down to 70 keV
In stars with temperatures above 20*10^6 K, hydrogen burning is dominated by
the CNO cycle. Its rate is determined by the slowest process, the
14N(p,gamma)15O reaction. Deep underground in Italy's Gran Sasso laboratory, at
the LUNA 400 kV accelerator, the cross section of this reaction has been
measured at energies much lower than ever achieved before. Using a windowless
gas target and a 4pi BGO summing detector, direct cross section data has been
obtained down to 70 keV, reaching a value of 0.24 picobarn. The Gamow peak has
been covered by experimental data for several scenarios of stable and explosive
hydrogen burning. In addition, the strength of the 259 keV resonance has been
remeasured. The thermonuclear reaction rate has been calculated for
temperatures 90 - 300 *10^6 K, for the first time with negligible impact from
extrapolations
Feasibility of low energy radiative capture experiments at the LUNA underground accelerator facility
The LUNA (Laboratory Underground for Nuclear Astrophysics) facility has been
designed to study nuclear reactions of astrophysical interest. It is located
deep underground in the Gran Sasso National Laboratory, Italy. Two
electrostatic accelerators, with 50 and 400 kV maximum voltage, in combination
with solid and gas target setups allowed to measure the total cross sections of
the radiative capture reactions H(p,)3He and
N(p,)O within their relevant Gamow peaks. We report on
the gamma background in the Gran Sasso laboratory measured by germanium and
bismuth germanate detectors, with and without an incident proton beam. A method
to localize the sources of beam induced background using the Doppler shift of
emitted gamma rays is presented. The feasibility of radiative capture studies
at energies of astrophysical interest is discussed for several experimental
scenarios.Comment: Submitted to Eur. Phys. J.
Observation of Radiative Decay
We report the observation of the decay with a
statistical significance of in 78.1 \ifb of data collected by the
Belle experiment at the KEKB collider. This is the first observation
of a flavor-changing radiative decay of a charmed meson. The Cabibbo- and
color-suppressed decays , are also observed for
the first time. We measure branching fractions \br(D^{0} \to \phi \gamma)
= [ 2.60^{+0.70}_{-0.61} \stat {}^{+0.15}_{-0.17} \syst ] \times 10^{-5},
\br(D^{0} \to \phi \pi^{0})
= [ 8.01 \pm 0.26 \stat \pm 0.47 \syst ] \times 10^{-4}, and \br(D^{0} \to
\phi \eta) = [ 1.48 \pm 0.47 \stat \pm 0.09 \syst ] \times 10^{-4}.Comment: 9 pages, 4 figures, Belle Preprint 2003-24, KEK Preprint 2003-75,
updated version of BELLE-CONF-0346 (contributed paper to the XXI
International Symposium on Lepton and Photon Interactions at High
Energies,Fermilab Aug 11-16,2003). to appear in Phys. Rev. Let
Observation of -> DsJ*(2317)+ K- decay
The decays and
are studied for the first time. A significant signal is observed in the
decay channel with . No signals are observed in
the ,
and decay modes, and upper limits are
obtained. The analysis is based on a dataset of 140 fb collected by the
Belle experiment at the asymmetric collider KEKB.Comment: 9 pages, 2 figures, submitted to PR
Study of time-dependent CP violation in B0 -> J/Psi pi0 decays
We report a measurement of CP asymmetry parameters in the decay B0(B0bar) ->
J/Psi pi0, which is governed by the b->c cbar d transition. The analysis is
based on a 140/fb data sample accumulated at the Upsilon(4S) resonance by the
belle detector at the KEKB asymmetric-energy e+e- collider. We fully
reconstruct one neutral B meson in the J/Psi pi0 final state. The accompanying
B meson flavor is identified by its decay products. From the distribution of
proper time intervals between the two B decays, we obtain the following
CP-violating parameters: S_{J/Psi pi0}=-0.72+-0.42+-0.09 and A_{J/Psi
pi0}=-0.01 +-0.29+-0.03.Comment: 5 pages, 2 figures, submitted to PR
Measurement of e^+e^- to pi^+pi^-J/psi Cross Section via Initial State Radiation at Belle
The cross section for e^+e^- to pi^+pi^-J/psi between 3.8 and 5.5 GeV/c^2 is
measured using a 548 fb^{-1} data sample collected on or near the Upsilon(4S)
resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2,
corresponding to the so called Y(4260), is observed. In addition, there is
another cluster of events at around 4.05 GeV/c^2. A fit using two interfering
Breit-Wigner shapes describes the data better than one that uses only the
Y(4260), especially for the lower mass side of the 4.25 GeV enhancement.Comment: 11 pages, 5 figures, 2 tables; version to appear in PR
Measurements of exclusive B_s^0 decays at the Y(5S) resonance
Several exclusive decays are studied using a 1.86 fb-1 data sample
collected at the Y(5S) resonance with the Belle detector at the KEKB asymmetric
energy e^+ e^- collider. In the decay mode we find 10
candidates and measure the corresponding branching fraction. Combining
the B_s^0 -> D_s^{(*)-} \pi^+, B_s^0 -> D_s^{(*)-} \rho^+, B_s^0 -> J/\psi \phi
and B_s^0 -> J/\psi \eta decay modes, a significant signal is observed.
The ratio \sigma (e^+ e^- -> B_s^* \bar{B}_s^*) / \sigma (e^+ e^- -> B_s^{(*)}
\bar{B}_s^{(*)}) = (93^{+7}_{-9} \pm 1)% is obtained at the Y(5S) energy,
indicating that meson production proceeds predominantly through the
creation of pairs. The and meson masses are
measured to be M(B_s^0)=(5370 \pm 1 \pm 3)MeV/c^2 and M(B_s^*)=(5418 \pm 1 \pm
3)MeV/c^2. Upper limits on the B_s^0 -> \gamma \gamma, B_s^0 -> \phi \gamma,
B_s^0 -> K^+ K^- and B_s^0 -> D_s^{(*)+} D_s^{(*)-} branching fractions are
also reported.Comment: 9 pages, 5 figures, published in Phys. Rev. D76, 012002 (2007
Observation of B+ -> proton Lambdabar gamma
We report the first observation of the radiative hyperonic B decay B+ ->
proton Lambdabar gamma, using a 140 fb-1 data sample recorded on the
Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy
e+e- collider. The measured branching fraction is B(B+ -> proton Lambdabar
gamma) = (2.16 ^{+0.58}_{-0.53} +- 0.20) times 10^{-6}. A search for B+ ->
proton Sigmabar gamma yields no significant signal, so we set a 90%
confidence-level upper limit on the branching fraction of B(B+ -> proton
Sigmabar gamma) < 3.3 times 10^{-6}.Comment: 12 pages, 4 figures, submitted to ICHEP2004, Beijing, Chin
Measurement of CP asymmetry in Cabibbo suppressed D0 decays
We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 ->
pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle
detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+
decays are used to correct for systematic detector effects. The results,
A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +-
0.12)%, are consistent with no CP violation.Comment: Submitted to Phys. Lett.
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