| 1. |
- Rapp, Östen, et al.
(författare)
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Electronic and atomic disorder in icosahedral AlPdRe
- 2008
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 20:11, s. 114120-
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Tidskriftsartikel (refereegranskat)abstract
- Relations between electronic and atomic disorder of i-AlPdRe have been investigated by studies of neutron irradiated and annealed samples. The advantage with this technique is that a single sample can be monitored over a significant range of varying electronic properties, without concern for any influence of varying impurities. X-ray diffraction, the electrical resistivity and its temperature dependence, and the magnetoresistance are studied. The results show that annealings of an irradiated sample lead to improvement of the atomic order, as reflected in increased intensities of the x-ray diffraction peaks, while electronic properties change in the direction of increasing electronic disorder towards a metal-insulator transition. The observed relation in quasicrystals that improved atomic structure is associated with stronger anomalies in transport properties is thus also seen in i-AlPdRe. In particular, the variation of the diffusion constant in the region of small values of the resistivity is found to be similar for annealed polygrain samples and for single grain samples with varying Pd concentration, as evaluated from literature data, indicating a similar development of electronic disorder in both sets of samples. However, the problem remains as to why the resistivity is small in single grain samples which are atomically well-ordered. The possibility of a strong sensitivity to concentration differences is pointed out.
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| 2. |
- Rapp, Östen, et al.
(författare)
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Neutron irradiation and annealing recovery in the AlPdRe quasicrystal
- 2006
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Ingår i: Low Temperature Physics, Pts A and B. - MELVILLE, NY : AMER INST PHYSICS. - 9780735403475 ; , s. 1307-1308
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Konferensbidrag (refereegranskat)abstract
- The effect of high energy neutron irradiation and subsequent low temperature annealings of icosahedral AlPdRe has been studied. For an insulating sample, brought into a metallic state by irradiation, the resistivity rho, at 4.2 K was found to increase with increased annealing temperature T-a, while the resistance ratio R=rho(4.2 K)/rho(295 K) increased according to a previously established general relation for as prepared samples. The intensity of X-ray diffraction peaks were found to increase with increasing T-a, thus indicating improved icosahedral order. It is concluded that irradiation and annealing offers a method to reversibly tune a single icosahedral AlPdRe sample over a range of R-values, that R is therefore not sensitive to external impurities, and is a useful parameter to tune the metal-insulator transition.
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| 3. |
- Hesselson, Stephanie E, et al.
(författare)
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Genetic variation in the proximal promoter of ABC and SLC superfamilies : liver and kidney specific expression and promoter activity predict variation
- 2009
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:9, s. e6942-
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Tidskriftsartikel (refereegranskat)abstract
- Membrane transporters play crucial roles in the cellular uptake and efflux of an array of small molecules including nutrients, environmental toxins, and many clinically used drugs. We hypothesized that common genetic variation in the proximal promoter regions of transporter genes contribute to observed variation in drug response. A total of 579 polymorphisms were identified in the proximal promoters (-250 to +50 bp) and flanking 5' sequence of 107 transporters in the ATP Binding Cassette (ABC) and Solute Carrier (SLC) superfamilies in 272 DNA samples from ethnically diverse populations. Many transporter promoters contained multiple common polymorphisms. Using a sliding window analysis, we observed that, on average, nucleotide diversity (pi) was lowest at approximately 300 bp upstream of the transcription start site, suggesting that this region may harbor important functional elements. The proximal promoters of transporters that were highly expressed in the liver had greater nucleotide diversity than those that were highly expressed in the kidney consistent with greater negative selective pressure on the promoters of kidney transporters. Twenty-one promoters were evaluated for activity using reporter assays. Greater nucleotide diversity was observed in promoters with strong activity compared to promoters with weak activity, suggesting that weak promoters are under more negative selective pressure than promoters with high activity. Collectively, these results suggest that the proximal promoter region of membrane transporters is rich in variation and that variants in these regions may play a role in interindividual variation in drug disposition and response.
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| 4. |
- Maddika, Subbareddy, et al.
(författare)
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Interaction with PI3-kinase contributes to the cytotoxic activity of Apoptin
- 2008
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Ingår i: Oncogene. - : Nature Publishing Group. - 0950-9232 .- 1476-5594. ; 27, s. 3060-3065
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Tidskriftsartikel (refereegranskat)abstract
- Apoptin, a small protein from the chicken anemia virus, has attracted attention because of its specificity in killing tumor cells. Localization of apoptin in the nucleus of tumor cells has been shown to be vital for proapoptotic activity, however, targeted expression of apoptin in the nucleus of normal cells does not harm the cells, indicating that nuclear localization of apoptin is insufficient for its cytotoxicity. Here, we demonstrate for the first time that apoptin interacts with the SH3 domain of p85, the regulatory subunit of phosphoinositide 3-kinase (PI3-K), through its proline-rich region. Apoptin derivatives devoid of this proline-rich region do not interact with p85, are unable to activate PI3-K, and show impaired apoptosis induction. Moreover, apoptin mutants containing the proline-rich domain are sufficient to elevate PI3-K activity and to induce apoptosis in cancer cells. Downregulation of p85 leads to nuclear exclusion of apoptin and impairs cell death induction, indicating that interaction with the p85 PI3-K subunit essentially contributes to the cytotoxic activity of apoptin.
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