| 1. |
- Wagner, C A, et al.
(författare)
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Effects of the serine/threonine kinase SGK1 on the epithelial Na(+) channel (ENaC) and CFTR : implications for cystic fibrosis.
- 2001
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Ingår i: Cellular Physiology and Biochemistry. - 1015-8987 .- 1421-9778. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Cystic fibrosis (CF) is characterized by impaired Cl(-) secretion and increased Na(+) reabsorption in several tissues including respiratory epithelium. Many CFTR mutations have been identified over the past years. However, only a poor correlation between the genotype and lung phenotype was found suggesting additional factors influencing the phenotype and course of the disease. The serine/threonine kinase SGK1 has recently been shown to stimulate the activity of the epithelial Na(+) channel ENaC. A variety of stimuli such as aldosterone, cell shrinkage, insulin or TGF-beta1 stimulate transcription and activate the SGK1 kinase. Here we further examined the effects of SGK1 on ENaC and CFTR which have mutual interactions and we analyzed sgk1 mRNA abundance in lung tissue from CF patients. Coexpression of CFTR and h-SGK1 in Xenopus oocytes increased ENaC currents as previously described. In addition CFTR mediated currents were also stimulated. h-SGK1 accelerated the expression of the amiloride sensitive Na(+)- current in Xenopus oocytes paralleled by increased ENaC-protein abundance in the oocyte membrane, an effect which was reversed by a h-SGK1(K127R) mutation lacking the ATP-binding site. The cation selectivity or Na(+) affinity were not affected. However, coexpression of h-SGK1 with ENaC altered the sensitivity of the Na(+)-channel to the inhibitors amiloride and triamterene. The inhibitory effect of CFTR expression on ENaC current was not affected by coexpression of h-SGK1 in Xenopus oocytes. Lung tissue from CF patients strongly expressed the serine/threonine kinase h-sgk1 which was not the case for non-CF lung tissue. Loss of CFTR function itself in a CF lung epithelial cell line did not increase SGK1 expression. In summary, enhanced expression of h-SGK1 in epithelial cells of CF-lung tissue may be a novel pathophysiological factor contributing to increased Na(+) channel activity and thus to increased Na(+) transport in CF.
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| 2. |
- Ongena, J., et al.
(författare)
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Recent progress on JET towards the ITER reference mode of operation at high density
- 2001
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 43, s. A11-A30
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Tidskriftsartikel (refereegranskat)abstract
- Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H-98(y.2) = 1 and densities up to n/n(Gw) similar to 1 are now routinely obtained. This has been possible (i) by using plasmas at high (delta similar to 0.5) and medium (delta similar to 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (delta similar to 0.5) and low (delta less than or equal to 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed.
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| 3. |
- Ubachs, W, et al.
(författare)
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Lifetime measurements on the c '(1)(4)Sigma(+)(u), v=0, 1 and 2 states of molecular nitrogen
- 2001
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Ingår i: Chemical Physics. - 0301-0104. ; 270:1, s. 215-225
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Tidskriftsartikel (refereegranskat)abstract
- Excited state lifetimes of c(4)('1)Sigma (+)(u), upsilon = 0-2 states of molecular nitrogen have been determined in a laboratory investigation using a picosecond XUV laser in a pump-probe configuration. For c(4)('1)Sigma (+)(u) upsilon = 0 the lifetime is tau = 740 +/- 50 ps, for the lowest rotational states. For higher rotational states a gradual shift towards tau = 495 ps is found in agreement with previous findings that these states are subject to predissociation. For c(4)(') Sigma (+)(u) upsilon = 1 no J-dependence is found and values for two isotopomers are reported: tau = 240 ps for (NN)-N-14-N-15 = 240 ps for (NN)-N-14-N-15. For c(4)('1)Sigma (+)(u) upsilon = 2 a lifetime for the lowest rotational states (J = 0-3) was derived: tau = 675 +/- 50 ps; for J = 11 a lifetime of tau less than or equal to 120 ps is deduced. All values for the lifetimes including the J-dependences are explained in a model based on Rydberg-valence interaction. (C) 2001 Elsevier Science B.V. All rights reserved.
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