143 research outputs found
G2 cell cycle arrest and apoptosis are induced in Burkitt's lymphoma cells by the anticancer agent oracin
AbstractThe cytotoxic effect of the new potential intercalating anticancer drug oracin was studied on Burkitt's lymphoma cell line that overexpressed bcl-2 (BL bcl-2) and a control transfectant without the bcl-2 gene (BL SV2). Oracin showed a marked cytostatic effect on both BL SV2 and BL bcl-2 cells. IC50, as measured by the MTT assay, was approx. 5-times greater for BL bcl-2 cells (5.0 μmol/l) than for BL SV2 cells (1.0 μmol/l). There was no significant increase in apoptosis after 24 h of treatment with oracin (1.0 μmol/l) in both cell lines. However, after 48 h from the removal of oracin in BL SV2 culture the levels of apoptotic and secondary necrotic cells increased to 20 and 37%, respectively. In contrast, BL bcl-2 cells treated in a similar manner showed only basal levels of apoptotic and secondary necrotic cells. Analysis of the cell cycle profiles showed a significant increase of S and G2/M phases of the cell cycle in both cell lines after 6 h of drug treatment (1.0 μmol/l). The cells were arrested in G2/M phase of the cell cycle after 24 h, with no significant changes in cell viability. After 72 h, the viable BL SV2 cells were still in G2/M, however, the viability of this culture had fallen to approx. 5%. Flow cytometry analysis of the DNA content revealed the presence of a `sub-G2' region, which represented the apoptotic cells. The BL SV2 cells died after 72 h while they were in the G2/M phase. Although the treated BL bcl-2 cells were similarly arrested in the G2/M phase, they nevertheless remained with a relatively high viability (68%)
Predicting promoters in phage genomes using machine learning models
The renewed interest in phages as antibacterial agents has led to the exponentially growing number of sequenced phage genomes. Therefore, the development of novel bioinformatics methods to automate and facilitate phage genome annotation is of utmost importance. The most difficult step of phage genome annotation is the identification of promoters. As the existing methods for predicting promoters are not well suited for phages, we used machine learning models for locating promoters in phage genomes. Several models were created, using different algorithms and datasets, which consisted of known phage promoter and non-promoter sequences. All models showed good performance, but the ANN model provided better results for the smaller dataset (92% of accuracy, 89% of precision and 87% of recall) and the SVM model returned better results for the larger dataset (93% of accuracy, 91% of precision and 80% of recall). Both models were applied to the genome of Pseudomonas phage phiPsa17 and were able to identify both types of promoters, host and phage, found in phage genomes.This study was supported by the Portuguese Foundation for Science andTechnology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and theProject POCI-01-0145-FEDER-029628. This work was also supported by BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fundunder the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio
Precision measurement of charged pion and kaon differential cross sections in electron-positron annihilation at Q = 10.52 GeV
Measurements of inclusive differential cross sections for charged pion and
kaon production in electron-positron annihilation have been carried out at a
center-of-mass energy of Q = 10.52 GeV. The measurements were performed with
the Belle detector at the KEKB electron-positron collider using a data sample
containing 113 million e+e- -> qqbar events, where q={u,d,s,c}. We present
charge-integrated differential cross sections d\sigma_h+-/dz for h+- = pi+-,
K+- as a function of the relative hadron energy z = 2*E_h / sqrt{s} from 0.2 to
0.98. The combined statistical and systematic uncertainties for pi+- (K+-) are
4% (4%) at z ~ 0.6 and 15% (24%) at z ~ 0.9. The cross sections are the first
measurements of the z-dependence of pion and kaon production for z > 0.7 as
well as the first precision cross section measurements at a center-of-mass
energy far below the Z^0 resonance used by the experiments at LEP and SLC.Comment: 7 pages, 3 figures. Ancillary file including all cross section and
uncertainty values with 10 pages, 5 figure
Observation of Mixing in Collisions
We observe mixing in the decay
using a data sample of integrated luminosity 976 fb collected with the
Belle detector at the KEKB asymmetric-energy collider. We measure the
mixing parameters and and the ratio of doubly Cabibbo-suppressed to
Cabibbo-favored decay rates , where the
uncertainties are statistical and systematic combined. Our measurement excludes
the no-mixing hypothesis at the 5.1 standard deviation level.Comment: 6 pages, 4 figure
Measurements of the masses and widths of the and baryons
We present measurements of the masses and decay widths of the baryonic states
and using a data sample
corresponding to an integrated luminosity of 711 fb collected with the
Belle detector at the KEKB asymmetric-energy collider operating at
the resonance. We report the mass differences with respect to
the baryon MeV/, MeV/,
MeV/, MeV/, and the decay widths
MeV/,
MeV/,
MeV/,
MeV/,
where the first uncertainties are statistical and the second are systematic.
The isospin mass splittings are measured to be
MeV/ and
MeV/. These results are the most precise to date.Comment: 13 pages, 4 figures, Submitted to PRD(RC
Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other B^0 decay modes with a four-pion final state
We present a study of the branching fraction of the decay B^0->rho0rho0 and
the fraction of longitudinally polarized rho0 mesons in this decay. The results
are obtained from the final data sample containing 772 million BBbar pairs
collected at the Y(4S) resonance with the Belle detector at the KEKB
asymmetric-energy e+e- collider. We find 166 +- 59 B^0 -> rho0 rho0 events
(including systematic uncertainties), corresponding to a branching fraction of
B(B^0->rho0rho0) = (1.02 +- 0.30 (stat) +- 0.15 (syst)) x 10^{-6} with a
significance of 3.4 standard deviations and a longitudinal polarization
fraction fL = 0.21^{+0.18}_{-0.22} (stat) +- 0.15 (syst). We use the
longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa
matrix angle phi_2 = (84.9 +- 13.5) degrees through an isospin analysis in the
B->rhorho system. We furthermore find 149 +- 49 B^0->f0rho0 events,
corresponding to B(B^0->f0rho0) x B(f0->pi+pi-) = (0.78 +- 0.22 (stat) +- 0.11
(syst)) x 10^{-6}, with a significance of 3.1 standard deviations. We find no
other significant contribution with the same final state, and set upper limits
at 90% confidence level on the (product) branching fractions,
B(B^0->pi+pi-pi+pi-)rho0pi+pi-)<12.0 x 10^{-6},
B(B^0->f0pi+pi-) x B(f0->pi+pi-) f0f0) x
B(f0->pi+pi-)^{2} < 0.2 x 10^{-6}.Comment: 21 pages, 20 figures, conference paper for the 2012th CKM workshop,
submitted to PR
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