| 671. |
- Ström, Anna-Lena, et al.
(författare)
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Cloning and expression analysis of the murine homolg of the Spinocerebellar ataxia type 7 (SCA7) gene
- 2002
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Ingår i: Gene. - : Elsevier. ; 285:1-2, s. 91-99
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Tidskriftsartikel (refereegranskat)abstract
- Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by the expansion of a polyglutamine tract in the protein ataxin-7, a protein of unknown function. In order to analyze the expression pattern of wild type ataxin-7 in detail, the murine SCA7 gene homolog was cloned and the expression pattern in mice analyzed. The SCA7 mouse and human gene exhibit a high degree of identity at both DNA (88.2%) and protein (88.7%) level. The CAG repeat region, known to be polymorphic in man, is conserved in mouse but contained only five repeats in all mouse strains analyzed. The arrestin homology domain and the nuclear localization signal found in human ataxin-7 is also conserved in the murine homolog. Expression of ataxin-7 was detected during mouse embryonic development and in all adult mouse tissues examined by northern and western blots. In brain, immunohistological staining revealed an ataxin-7 expression pattern similar to that in human, with ataxin-7 expression in cerebellum, several brainstem nuclei, cerebral cortex and hippocampus. Our data show high conservation of ataxin-7 both structurally and at the level of expression, suggesting a conserved role for the protein in mice and humans.
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| 672. |
- Sullivan, Kirk P. H., et al.
(författare)
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Self-assessment in autonomous computer-aided L2 writing
- 2002
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Ingår i: ELT Journal. - Oxford : Oxford University Press. - 0951-0893 .- 1477-4526. ; 56:3, s. 258-266
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the results of a study carried out in Sweden to investigate the promotion of self‐assessment and reflection in the adult second language (L2) classroom. A method is proposed in which the computer is used first to record a writing session, and later to replay the entire text production in retrospective peer sessions. The method provides the students with an opportunity to look into their own composing processes both linguistically and holistically, as they view and discuss the reasons behind the different actions during the writing process. Results show that after using the method, all writers experienced useful, although different, insights into their own writing behaviours. Furthermore, this method is not restricted to an L2 environment, but is likely to be effective in other learning situations where reflection is useful for the acquisition process.
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| 673. |
- Sun, J. G.
(författare)
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Condition numbers of algebraic Riccati equations in the Frobenius norm
- 2002
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Ingår i: Linear Algebra and Its Applications. ; 350, s. 237-261
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Tidskriftsartikel (refereegranskat)abstract
- Consider the continuous-time algebraic Riccati equation (CARE) and the discrete-time algebraic Riccati equation (DARE) which arise in linear control and system theory. It is known that appropriate assumptions on the coefficient matrices guarantee the existence and uniqueness of Hermitian positive semidefinite stabilizing solutions. In this note, we apply the theory of condition developed by Rice to define condition numbers of the CARE and DARE in the Frobenius norm, and derive explicit expressions of the condition numbers in a uniform manner. Both the complex case and real case are considered, and connections to certain existing condition numbers of the CARE and DARE are discussed. (C) 2002 Elsevier Science Inc. All rights reserved.
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| 674. |
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| 675. |
- Sundin, Anna-Maja, et al.
(författare)
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Rapid and sensitive method for the analysis of carbon monoxide in blood using gas chromatography with flame ionisation detection
- 2002
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 766:1, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- In order to measure changes in physiological CO concentrations in blood with good accuracy, a method was developed using gas chromatography with flame ionisation detection (250 degrees C). A nickel catalyst system was fitted to convert CO to methane at 375 degrees C after separation with a molecular sieve column at 35 degrees C. Helium was used as carrier at 30 ml/min. Porcine or human blood (400 microl) was sampled in gastight tubes and treated with sulfuric acid and saponin (800 microl). Accuracy was 1.4% and 1.5% (RSD), respectively. Precision was 2.8% (porcine blood). Limit of detection was 0.01 nmol/ml gas and limit of quantification 12 nmol/ml blood. Calibration was made in the interval 12-514 nmol/ml blood (corresponding to 0.1-6% COHb). Samples were stable for at least a month at +4 degrees C. This paper describes a method with high sensitivity and good accuracy, suitable for analysis of low CO concentrations.
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| 676. |
- Sundin, Charlotta, et al.
(författare)
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Type IV pili are not specifically required for contact dependent translocation of exoenzymes by Pseudomonas aeruginosa
- 2002
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Ingår i: Microbial Pathogenesis. - : Elsevier. - 0882-4010. ; 33:6, s. 265-277
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Tidskriftsartikel (refereegranskat)abstract
- The type III secretion system (TTSS) of the opportunistic pathogen Pseudomonas aeruginosa enables the bacterium to deliver exoenzymes directly into the eukaryotic cell. In this study we have investigated the role of key factors involved in this process. We could demonstrate that the translocators PopB, PopD and PcrV are absolutely required for delivery of Exoenzyme S into host cells. By analyzing different Tfp (type IV pili) mutants we could establish a correlation between the frequency of bacteria binding to the host cell and the levels of translocated ExoS, thereby verifying that the process is contact dependent. However, there was no absolute requirement for the Tfp per se, since the pilus could be substituted with a different type of adhesin, the non-fimbrial adhesin pH6 antigen of Yersinia pestis. Taken together, our results demonstrate that binding to establish close contact between the type III secretion organelle and the host cell is essential for translocation, while the additional activities of Tfp are not essential for the delivery of TTSS proteins.
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| 677. |
- Sundman-Eriksson, Ingrid, et al.
(författare)
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[(3)H]Tiagabine binding to GABA transporter-1 (GAT-1) in suicidal depression.
- 2002
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Ingår i: Journal of Affective Disorders. - 0165-0327 .- 1573-2517. ; 71:1-3, s. 29-33
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In depressive disorders, alterations of GABA concentrations and number of postsynaptic GABA related receptor binding sites, as well as antidepressant effects exerted by GABA agonists, suggest a pathogenetic involvement of the GABA system. METHOD: The binding of the presynaptic GABA ligand [(3)H]tiagabine to GABA transporter-1 (GAT-1) was studied in post mortem human frontal cortex and cingulate gyrus from 13 suicide victims and 19 controls without known neurological or psychiatric disorder. RESULTS: No differences were found between the suicide victims and the controls with regard to the number of [(3)H]tiagabine binding sites (B(max)) or apparent affinity (K(d)). LIMITATIONS: The study was limited to two brain regions. CONCLUSION: Findings in other studies of alterations in the GABA system in depression seem according to the present results not to be associated with significant changes in the GABA uptake binding sites in the regions investigated.
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| 678. |
- Sundqvist, Bertil
(författare)
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Carbon nanostructures under high pressure
- 2002
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Ingår i: Journal of Physics Condensed Matter vol. 14. - Bristol : Institute of Physics. ; , s. 10449-10452
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Konferensbidrag (refereegranskat)abstract
- Results from recent high-pressure experiments in the field of fullerenes are briefly reviewed. In particular, new results on one-, two- and three-dimensional polymerized C60 and C70 are discussed. Results discussed include the first synthesis of a well defined, one-dimensional polymer based on C70, transformations from two-dimensional (2D) to three-dimensional phases in C60, and doping of 2D C60 polymers.
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| 679. |
- Sundqvist, Bertil, et al.
(författare)
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Dielectric properties of C60 under high pressure
- 2002
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Ingår i: Journal of Physics: Condensed Matter vol. 14 issue no. 44. - Bristol : Institute of Physics. ; , s. 10437-10440
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Konferensbidrag (refereegranskat)abstract
- The dielectric properties of C60 have been measured as functions of temperature and hydrostatic pressure in the ranges 80–370 K and 0–0.8 GPa. The results show sharp anomalies at the rotational transition above 260 K and large relaxation peaks associated with the rotational 'glass transition'. From the measured frequencies of the loss peaks we calculate the energy barrier for molecular jumping between the 'pentagon' and 'hexagon' molecular orientations. The energy barrier increases by 13% GPa−1.
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| 680. |
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