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| 2. |
- Knecht, W., et al.
(author)
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Drosophila deoxyribonucleoside kinase mutants with enhanced ability to phosphorylate purine analogs
- 2007
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In: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 14:17, s. 1278-1286
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Journal article (peer-reviewed)abstract
- Transduced deoxyribonucleoside kinases (dNK) can be used to kill recipient cells in combination with nucleoside prodrugs. The Drosophila melanogaster multisubstrate dNK (Dm-dNK) displays a superior turnover rate and has a great plasticity regarding its substrates. We used directed evolution to create Dm-dNK mutants with increased specificity for several nucleoside analogs (NAs) used as anticancer or antiviral drugs. Four mutants were characterized for the ability to sensitize Escherichia coli toward analogs and for their substrate specificity and kinetic parameters. The mutants had a reduced ability to phosphorylate pyrimidines, while the ability to phosphorylate purine analogs was relatively similar to the wild-type enzyme. We selected two mutants, for expression in the osteosarcoma 143B, the glioblastoma U-87M-G and the breast cancer MCF7 cell lines. The sensitivities of the transduced cell lines in the presence of the NAs fludarabine (F-AraA), cladribine (CdA), vidarabine and cytarabine were compared to the parental cell lines. The sensitivity of 143B cells was increased by 470-fold in the presence of CdA and of U-87M-G cells by 435fold in the presence of F-AraA. We also show that a choice of the selection and screening system plays a crucial role when optimizing suicide genes by directed evolution.
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| 3. |
- Niedermaier, O., et al.
(author)
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"Safe" Coulomb excitation of Mg-30
- 2005
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 94:17, s. 172501 (artno)-
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Journal article (peer-reviewed)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 4. |
- Niedermaier, O., et al.
(author)
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The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE
- 2005
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In: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 752, s. 273-273
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Journal article (peer-reviewed)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 5. |
- Scheit, H., et al.
(author)
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Coulomb excitation of neutron-rich beams at REX-ISOLDE
- 2005
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In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25:Suppl. 1, s. 397-402
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Conference paper (peer-reviewed)abstract
- After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium gamma spectrometer MINIBALL.
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