1,081 research outputs found
Evaluation der Tumorsuppressoraktivität transformationsdefekter Adenovirus-Serotyp 5 E1A-Mutanten
Neben der Verwendung von E1A-Proteinen bei der Aufklärung zellulärer Prozesse wurde in den letzten Jahren zunehmende Aufmerksamkeit auf die Tumorsuppressoraktivität von E1A gelenkt. E1A-Proteine sind in der Lage, die Tumorigenität und Metastasierung von Tumorzellen deutlich zu reduzieren. Dies ist gerade im Hinblick auf die unzulänglichen Heilungsmethoden vieler maligner Erkrankungen interessant, die es dringend notwendig machen, neue Therapiemöglichkeiten zu entwickeln. Nach heutigen Erkenntnissen kommt E1A für die Behandlung von Tumoren als antineoplastisches Transgen in Frage. Eine Problematik für den Einsatz als therapeutisches Agens ergibt sich jedoch aus der Fähigkeit von E1A-Proteinen, primäre Zellen in Kooperation mit einem weiteren Onkogen zu transformieren.
In der vorliegenden Arbeit konnte gezeigt werden, dass transformationsdefekte Adenovirus-Serotyp 5 E1A-Mutanten in unterschiedlichen Tumormodellen Tumorsuppressoraktivität haben. Die E1A-Mutanten supprimierten die Tumorigenität der hoch metastasierenden Melanomzelllinie, BLM, und der Bronchialkarzinomzelllinie, H1299. Die Repression der Tumorigenität ist dabei unabhängig von der Repression des HER-2/neu-Promotors und ebenfalls unabhängig von der Induktion epithelialer Gene. Die E1A-Mutanten waren darüber hinaus in der Lage, die Aktivität einer metastasierungsrelevanten Protease, der MMP-2, zu reprimieren. Die Behandlung der chemoresistenten Zelllinien mit in der Therapie von Tumoren eingesetzten Zytostatika verdeutlichte, dass die Expression der transformationsdefekten E1A-Mutanten die Zytostatikaresistenz der Zelllinien aufheben konnten. Es gelang somit auch beim Einsatz geringer Mengen der DNA-schädigenden Substanzen, die Zelllinien für die Wirkung zu sensibilisieren. In der vorliegenden Arbeit konnte gezeigt werden, dass die Expression der konservierten Region 3 zusammen mit dem Exon 2 der E1A-Proteine ausreicht, um eine effektive Tumorsuppression zu erzielen. Die Mutanten, in denen diese beiden Regionen erhalten war, hatten eine über die des E1AWT-Proteins hinausgehende tumorsupprimierende Aktivität.
Es konnte unter Beweis gestellt werden, dass mutierte E1A-Proteine auch unabhängig von ihrem Transformationspotential weitreichende tumorsupprimierende Funktionen ausüben können. Die hier vorgestellten tumorsupprimierenden E1A-Mutanten sind daher für den Einsatz als therapeutische Transgene in der Tumortherapie geeignet
Measurement of the Partial Widths Ratio Gamma(Ds*+ -> Ds+ pi0) / Gamma(Ds*+ -> Ds+ gamma) at the BABAR Experiment
Unter Benutzng von 90.4/fb Daten, die das BABAR-Experiment in den Jahren 1999 bis 2002 genommen hat, wurden die Zerfälle Ds*+ -> Ds+ pi0 und Ds*+ -> Ds+ gamma mit zwei verschiedenen Methoden rekonstruiert. Die Rekonstruktions-Effizienzen wurden mittels Signal-Monte Carlo-Ereignissen und D*0-Zerfällen ermittelt. Auf diese Weise wurde das Partialbreiten-Verhältnis Gamma(Ds*+ -> Ds+ pi0) / Gamma(Ds*+ -> Ds+ gamma) auf vier verschiedene Weisen gemessen. Zusätzlich wurde das Partialbreiten-Verhältnis Gamma(D*0 -> D0 pi0) / Gamma(D*0 -> D0 gamma) gemessen.Using 90.4/fb of data taken at the BABAR experiment in the years 1999 to 2002, the decays Ds*+ -> Ds+ pi0 and Ds*+ -> Ds+ gamma have been reconstructed with two different methods. Signal Monte Carlo events as well as D*0 decays have been used to determine the reconstruction efficiencies. Thereby, the partial widths ratio Gamma(Ds*+ -> Ds+ pi0) / Gamma(Ds*+ -> Ds+ gamma) has been measured in four different ways. Additionally, the partial widths ratio Gamma(D*0 -> D0 pi0) / Gamma(D*0 -> D0 gamma) has been measured
Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APS.We report a measurement of the branching fraction of the decay B0→D*+D*- and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4 fb-1 collected at the Υ(4S) resonance during 1999–2000, we have reconstructed 38 candidate signal events in the mode B0→D*+D*- with an estimated background of 6.2±0.5 events. From these events, we determine the branching fraction to be B(B0→D*+D*-)=[8.3±1.6(stat)±1.2(syst)]×10-4. The measured CP-odd fraction of the final state is 0.22±0.18(stat)±0.03(syst).This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A.P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Measurement of the Branching Fraction for B- --> D0 K*-
We present a measurement of the branching fraction for the decay B- --> D0
K*- using a sample of approximately 86 million BBbar pairs collected by the
BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is
detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the
K*- through its decay to K0S pi-. We measure the branching fraction to be
B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.Comment: 7 pages, 1 postscript figure, submitted to Phys. Rev. D (Rapid
Communications
A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)
We present a measurement of time-dependent CP-violating asymmetries in
neutral B meson decays collected with the BABAR detector at the PEP-II
asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data
sample consists of 29.7 recorded at the
resonance and 3.9 off-resonance. One of the neutral B mesons,
which are produced in pairs at the , is fully reconstructed in
the CP decay modes , , , () and , or in flavor-eigenstate
modes involving and (). The flavor of the other neutral B meson is tagged at the time of
its decay, mainly with the charge of identified leptons and kaons. The proper
time elapsed between the decays is determined by measuring the distance between
the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample
finds . The value of the asymmetry amplitude is determined from
a simultaneous maximum-likelihood fit to the time-difference distribution of
the flavor-eigenstate sample and about 642 tagged decays in the
CP-eigenstate modes. We find , demonstrating that CP violation exists in the neutral B meson
system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review
Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at √s=10.6 GeV
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APSNew measurements of Ds+ and Ds*+ meson production rates from B decays and from qq̅ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb-1 of data on the Υ(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(B⃗Ds+X)=(10.93±0.19±0.58±2.73)% and B(B⃗Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e-→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e-→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B⃗Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B⃗Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.This work was supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the Swiss NSF, A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Evidence for the Rare Decay B -> K*ll and Measurement of the B -> Kll Branching Fraction
We present evidence for the flavor-changing neutral current decay and a measurement of the branching fraction for the related
process , where is either an or
pair. These decays are highly suppressed in the Standard Model,
and they are sensitive to contributions from new particles in the intermediate
state. The data sample comprises
decays collected with the Babar detector at the PEP-II storage ring.
Averaging over isospin and lepton flavor, we obtain the branching
fractions and , where the
uncertainties are statistical and systematic, respectively. The significance of
the signal is over , while for it is .Comment: 7 pages, 2 postscript figues, submitted to Phys. Rev. Let
Measurement of Branching Fraction and Dalitz Distribution for B0->D(*)+/- K0 pi-/+ Decays
We present measurements of the branching fractions for the three-body decays
B0 -> D(*)-/+ K0 pi^+/-B0 -> D(*)-/+ K*+/- using
a sample of approximately 88 million BBbar pairs collected by the BABAR
detector at the PEP-II asymmetric energy storage ring.
We measure:
B(B0->D-/+ K0 pi+/-)=(4.9 +/- 0.7(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K0 pi+/-)=(3.0 +/- 0.7(stat) +/- 0.3 (syst)) 10^{-4}
B(B0->D-/+ K*+/-)=(4.6 +/- 0.6(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K*+/-)=(3.2 +/- 0.6(stat) +/- 0.3 (syst)) 10^{-4}
From these measurements we determine the fractions of resonant events to be :
f(B0-> D-/+ K*+/-) = 0.63 +/- 0.08(stat) +/- 0.04(syst) f(B0-> D*-/+ K*+/-) =
0.72 +/- 0.14(stat) +/- 0.05(syst)Comment: 7 pages, 3 figures submitted to Phys. Rev. Let
Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass
energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with
the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum
we have obtained the products of branching fractions for the omega and phi
mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and
B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the
e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range
1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events
have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18
+/- 0.19)% has been measured.Comment: 21 pages, 37 postscript figues, submitted to Phys. Rev.
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