| 1. |
- Szymanski, J. J., et al.
(author)
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MEGA : A search for the decay mu –> e gamma
- 1994
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In: Intersections between particle and nuclear physics. Proceedings, 5th Conference, St. Petersburg, USA, May 31-June 6, 1994. ; , s. 789-792
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Conference paper (peer-reviewed)
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| 2. |
- Amann, F., et al.
(author)
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A search for murarregamma at the level of 10-13
- 1991
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In: Proceedings of the 25th International Conference on High Energy Physics. - 9810024347 ; , s. 1070-1071
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Conference paper (peer-reviewed)abstract
- The MEGA experiment, which is a search for the decay murarregamma with a branching ratio sensitivity of about 10-13, employs highly modular, fast detectors, state-of-the-art electronics, and a staged trigger with on-line filters. The detectors are contained in a 1.5-T solenoidal field produced by a superconducting magnet. Positrons are confined to the central region and are measured by a set of thin MWPCs. Photons are measured by one of four layers of pair spectrometers in the outer region. Most aspects of the design have been validated in engineering runs; data taking will begin in 1990 with much of the electron arm and one pair spectrometer layer installed.
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| 3. |
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| 4. |
- Egholm, M., et al.
(author)
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PNA HYBRIDIZES TO COMPLEMENTARY OLIGONUCLEOTIDES OBEYING THE WATSON-CRICK HYDROGEN-BONDING RULES
- 1993
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 365:6446, s. 566-568
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Journal article (peer-reviewed)abstract
- DNA ANALOGUES are currently being intensely investigated owing to their potential as gene-targeted drugs1-3. Furthermore, their properties and interaction with DNA and RNA could provide a better understanding of the structural features of natural DNA that determine its unique chemical, biological and genetic properties3,4. We recently designed a DNA analogue, PNA, in which the backbone is structurally homomorphous with the deoxyribose backbone and consists of N-(2-aminoethyl)glycine units to which the nucleobases are attached5-9. We showed that PNA oligomers containing solely thymine and cytosine can hybridize to complementary oligonucleotides, presumably by forming Watson-Crick-Hoogsteen (PNA)2-DNA triplexes, which are much more stable than the corresponding DNA-DNA duplexes5-7, and bind to double-stranded DNA by strand displacement5,8. We report here that PNA containing all four natural nucleobases hybridizes to complementary oligonucleotides obeying the Watson-Crick base-pairing rules, and thus is a true DNA mimic in terms of base-pair recognition.
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| 5. |
- Eriksson, M., et al.
(author)
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LOCATION OF EXCIMER-FORMING ADDUCTS OF (+)-ANTI-BENZO A PYRENE DIOL EPOXIDE IN DNA
- 1993
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 115:5, s. 1639-1644
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Journal article (peer-reviewed)abstract
- Covalent adducts of the carcinogenic polycyclic aromatic hydrocarbon (+)-anti-benzo[a]pyrene 7,8-dihydrodiol 9,10-epoxide ((+)-anti-BPDE) in polynucleotides have been studied by fluorescence spectroscopy. The pyrenyl chromophores of the BPDE adducts, linked by the C10 atom to the exocyclic nitrogen of guanine, interact in the photoexcited state, as evidenced by excimer fluorescence. Strong BPDE excimer fluorescence is observed in the alternating poly(dGdC).poly(dGdC) sequence, whereas it is weak in the homopolymeric poly(dG).poly(dC) and in calf thymus DNA. No excimer fluorescence is observed for the BPDE adducts in poly(dAdC).poly(dGdT) or poly(dAdG).poly(dCdT). It is concluded that the formation of BPDE excimers in polynucleotides requires binding to guanines on different strands on consecutive basepairs. The experimental results are supported by graphics modeling and energy minimization of BPDE adducts in various oligonucleotide sequences. The results show that the most favorable arrangement for excimer formation of the BPDE-dG adducts is in a 5'(dCdG-BPDE).5'(dCdG-BPDE) sequence, where the pyrenyl chromophores interact in the minor groove.
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| 6. |
- Graslund, A., et al.
(author)
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DYNAMICS OF BENZO A PYRENE DIOL EPOXIDE ADDUCTS IN POLY(DG-DC) . (DG-DC) STUDIED BY SYNCHROTRON EXCITED FLUORESCENCE POLARIZATION ANISOTROPY DECAY
- 1992
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In: Biophysical Chemistry. - : Elsevier BV. - 1873-4200 .- 0301-4622. ; 44:1, s. 21-28
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Journal article (peer-reviewed)abstract
- Time-resolved fluorescence studies have been performed on (+)-anti-7,8-dihydrodiol-9,10-epoxy-benzo[a]pyrene adducts in double-stranded poly(dG-dC) . (dG-dC). Part of the adduct population gives rise to excimer fluorescence. The heterogeneous fluorescence emission decay curves at 22-degrees-C could be resolved into three components with lifetimes: 0.4 ns, 3 ns and 24 ns for the total fluorescence (monomer and excimer emission), and 0.5 ns, 5 ns and 24 ns, respectively, for excimer emission alone. The relative amplitudes for the longer lifetimes were larger for the pure excimer population than for the mixed population. The fluorescence polarization anisotropy decay curves were resolved into two components of rotational correlation times: 0.4 ns and 25 ns for the total fluorescence and 0.3 ns and 33 ns for the excimer fluorescence. We interpret the two rotational correlation times to correspond to local motion of the adduct and segmental motion of the polynucleotide, respectively.
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| 7. |
- Kim, A.S., et al.
(author)
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Fracture strength testing of δ-alumina fibres with variable diameters and lengths
- 1993
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In: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 47:4, s. 331-333
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Journal article (peer-reviewed)abstract
- Tensile tests were performed on individual δ-alumina fibres (Saffil, RF grade). The results revealed a large scatter in strengths and a clear dependence of the fracture strength on the specimen volume. The tests were evaluated on the basis of the Weibull probability function, a special modification of the Weibull analysis being developed that successfully copes with the problem of testing fibres with various diameters and test lengths. For the sample studied the Weibull modulus, m, was found to be 2·2, with a scaling constant δ0 = 6·0 MPa (units of volume mm3; i.e. V0 = 1 mm3).
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| 8. |
- Nordén, Bengt, 1945, et al.
(author)
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DNA INTERACTION WITH CHIRAL METAL-COMPLEXES
- 1991
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In: Nucleosides and Nucleotides. - : Informa UK Limited. - 0732-8311 .- 1532-2335. ; 10:1-3, s. 195-205
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Journal article (peer-reviewed)abstract
- Despite extensive study of DNA interaction with propeller-shaped metal complexes, such as the DELTA and LAMBDA enantiomers of [Ru(1,10-phenanthroline)3]2+, the basis for their enantioselectivity, and even their binding modes, are not yet fully understood. H-1 NMR studies of the interactions with the self-complementary oligonucleotide d(CGCGATCGCG)2 indicate that both enantiomers bind into the minor groove of the central AT-TA region, but with a rapid exchange between the bound and free states. Flow linear dichroism (FLD) and circular dichroism (CD) show different binding geometries for the two enantiomers. These two geometries are found in natural DNA as well as in a number of different B form polynucleotides, virtually independent of base composition and of methylation. The DNA interaction with the [Ru(1,10-phenanthroline)3]2+ complexes will be reconsidered in the light of NMR, FLD, CD and fluorescence results.
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| 9. |
- Ponten, I., et al.
(author)
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SPECTROSCOPIC STUDIES OF THE TRANS ADDUCTS DERIVED FROM (+)-ANTI-BENZO A PYRENE-7,8-DIHYDRODIOL-9,10-EPOXIDE AND (-)-ANTI-BENZO A PYRENE-7,8-DIHYDRODIOL-9,10-EPOXIDE AND THE OLIGONUCLEOTIDE 5'-D(CCTATAGATATCC)
- 1994
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In: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 15:10, s. 2207-2213
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Journal article (peer-reviewed)abstract
- The oligonucleotide 5'-d(CCTATAGATATCC) has been reacted with the (+)- or (-)-enantiomers of trans-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-and (-)-anti-BPDE respectively]. Consistent with previous studies employing single-stranded oligonucleotides, adduct formation of both anti-BPDE enantiomers preferentially involved trans-addition of the C10 position of the diol-epoxide to the exocyclic nitrogen of deoxyguanosine [in the following abbreviated as (+)-BPDE(t)-N-2-G and (-)-BPDE(t)-N-2-G adducts respectively]. The unmodified or (+)-BPDE(t)-N-2-G-modified oligonucleotide was allowed to form duplexes with the complementary sequence 5'-d(GGATATCTATAGG) or sequences in which C has been replaced with T, G or A and analysed with regard to thermal stability. The presence of a (+)-BPDE(t)-N-2-G adduct in oligonucleotide duplexes substantially decreased the value of the melting point relative to the corresponding unmodified duplex. In mismatched complexes containing the (+)-BPDE(t)-N-2-G adduct, a further decrease in thermal stability was observed. The presence of a (+)-BPDE(t)-N-2-G adduct did not seem to change the extent of hyperchromicity (approximate to 20%) upon melting. 5'-d(GGATATCTATAGG) or strands in which C was replaced with T,G or A were gradually added to (+)- or (-)-BPDE(t)-N-2-G-modified oligonucleotides and the fluorescence emission intensity was determined. In all cases with (+)-BPDE(t)-N-2-G, except when C was replaced with A in the complement, the fluorescence intensity steadily decreased and became constant at equal strand concentrations. When a strand containing A in place of C was gradually added to the (+)-BPDE(t)-N-2-G oligonucleotide, a marked increase in the fluorescence intensity was observed (>3-fold). In contrast, addition of strands containing A, T or G to the (-)-BPDE(t)-N-2-G-modified oligonucleotide increased tbe fluorescence intensity from 1.5- to >5-fold. Addition of the fully complementary sequence to the (-)-BPDE(t)-N-2-G-containing oligonucleotide resulted in reduced fluorescence, however less pronounced than with the (+)-BPDE(t)-N-2-G-modified analogue. Significant changes in spectral properties of the adducts were observed in the duplexes. The absorption and fluorescence excitation maxima of the single-stranded (+)-BPDE(t)-N-2-G-modified oligonucleotide were at 353 nm. Insertion of C or A opposite the adduct caused a significant shift of these maxima to shorter wavelengths (347-348 nm). Addition of acrylamide, a fluorescence quencher, reduced the fluorescence intensity in all cases, but to variable extents. The adducts not quenchable by acrylamide demonstrate spectral properties similar to those of the single-stranded (+)-BPDE(t)-N-2-G-modified oligonucleotide.
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