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- Singh, A K, et al.
(författare)
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CFTR and its key role in in vivo resting and luminal acid-induced duodenal HCO3-secretion
- 2008
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 193:4, s. 357-365
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: We investigated the role of the recently discovered, villous-expressed anion exchanger Slc26a6 (PAT1) and the predominantly crypt-expressed cystic fibrosis transmembrane regulator (CFTR) in basal and acid-stimulated murine duodenal HCO3− secretion in vivo, and the influence of blood HCO3− concentration on both.Methods: The proximal duodenum of anaesthetized mice was perfused in situ, and HCO3− secretion was determined by back-titration. Duodenal mucosal permeability was assessed by determining 51Cr-EDTA leakage from blood to lumen.Results: Compared with wild type (WT) littermates basal duodenal HCO3− secretory rates were slightly reduced in Slc26-deficient mice at low (∼21 mm), and markedly reduced at high blood HCO3− concentration (∼29 mm). In contrast, basal HCO3− secretion was markedly reduced in CFTR-deficient mice compared with WT littermates both at high and low blood HCO3− concentration. A short-term application of luminal acid increased duodenal HCO3− secretory rate in Slc26a6-deficient and WT mice to the same degree, but had no stimulatory effect in the absence of CFTR. Luminal acidification to pH 2.5 did not alter duodenal permeability.Conclusions: The involvement of Slc26a6 in basal HCO3− secretion in murine duodenum in vivo is critically dependent on the systemic acid/base status, and this transporter is not involved in acid-stimulated HCO3− secretion. The presence of CFTR is essential for basal and acid-induced HCO3− secretion irrespective of acid/base status. This suggests a coupled action of Slc26a6 with CFTR for murine basal duodenal HCO3− secretion, but not acid-stimulated secretion, in vivo.
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| 2. |
- Schaefer, D., et al.
(författare)
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Compact X-ray microscopes for EUV- and soft X-radiation with spectral imaging capabilities
- 2006
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Ingår i: Advances in X-Ray/EUV Optics, Components, and Applications. - : SPIE. - 0819463965 ; , s. 31704-31704
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Konferensbidrag (refereegranskat)abstract
- We report on a compact full-field transmission microscope (CTXM) and a scanning transmission microscope (CST'XM) developed for imaging at laboratory scale X-ray sources. The microscopes are based on zone plates for imaging in the EUV and water window region (wavelength 2.3 nm to 4.4 mn). The radiation for the full-field microscope is generated by focusing short laser pulses with an energy of 100 mJ on a 20 gm cryogenic liquid nitrogen jet. A condenser zone plate in conjunction with an aperture is used to provide monochromatic sample illumination. This allows for easy wavelength selection within the N-2,-Emission spectrum. Thus, the presented setup offers the possibility of spectral imaging. A micro zone plate generates a magnified image detected by a back illuminated TE-cooled CCD camera (1,340 x 1,300 pixel). The actual configuration provides magnifications up to 1,000x at exposure times in a range of a few ten minutes with sub-100 nm resolution. Our compact scanning microscope (CSTXM) operates with a zone plate, focusing the radiation onto a sample which is placed on a piezo driven xy-stage with 1 nm lateral resolution. Using high-harmonic radiation at 13 nm wavelength sub-micron resolution is achieved. With light at 17 nm wavelength originating from the O-VI emission line of a laser plasma source based on an ethanol jet, 500 nm structures were imaged in less than 20 minutes resulting in an 100 x 40 pixel image.
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