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- Andersson, C, et al.
(författare)
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Cystic fibrosis transmembrane conductance regulator (CFTR) activity in nasal epithelial cells from cystic fibrosis patients with severe genotypes
- 2002
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Ingår i: Clinical science (London, England : 1979). - : Portland Press Ltd.. - 0143-5221 .- 1470-8736. ; 103:4, s. 417-424
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Tidskriftsartikel (refereegranskat)abstract
- Cystic fibrosis is a heterogenic disease, in which the phenotype can also vary for patients with the same genotype. In the present study the function of the cystic fibrosis transmembrane conductance regulator (CFTR) in nasal epithelial cells from 19 adult patients with cystic fibrosis was investigated. All patients had severe mutations, whereby no or little functional CFTR is expected in the plasma membrane. Of the patients, 15 were homozygous for ΔF508-CFTR (i.e. CTFR lacking residue Phe-508). The others were ΔF508-heterozygous with 3659delC, 394delTT or 2183AA→G. Nasal epithelial cells, obtained by nasal brushings, were loaded with the fluorescent probe N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide to measure Cl- efflux. In most of the cystic fibrosis patients, forskolin plus isobutylmethylxanthine was unable to elicit any response. Unexpectedly, cells from three cystic fibrosis patients (two ΔF508/ΔF508 patients and one ΔF508/3659delC patient) responded to stimulation in a wild-type manner. It was investigated whether this residual chloride transport function was associated with a milder phenotype. Clinical parameters studied were lung function, number of antibiotic courses, Shwachman score, Bhalla score, age at chronic colonization with Pseudomonas aeruginosa and the pattern of essential fatty acids in serum phospholipids. Unknown factors may affect the presence of functional CFTR in patients with severe CFTR mutations. However, we could not find a correlation between the response to cAMP and any of the phenotype parameters. It appears that functional cAMP transport in the nasal epithelium is no guarantee of a mild phenotype and, conversely, that a patient lacking cAMP-dependent chloride transport can develop a mild phenotype.
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- Andersson, C, et al.
(författare)
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Determination of chloride efflux by X-ray microanalysis versus MQAE-fluorescence
- 2002
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Ingår i: Microscopy research and technique (Print). - : Wiley. - 1059-910X .- 1097-0029. ; 59:6, s. 531-355
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Tidskriftsartikel (refereegranskat)abstract
- The importance of chloride channels for the cell is demonstrated by a number of serious human diseases that are due to mutations in chloride channels. The most well-known of these diseases is cystic fibrosis. Investigations into the mechanisms of the disease and possible treatments require the study of chloride fluxes at the level of individual cells. The present study compares two methods for studies of chloride transport: X-ray microanalysis and MQAE fluorescence with image analysis. As an experimental system, the cAMP-activated chloride channel in cultured respiratory epithelial cells was chosen. Both methods showed that stimulation with the cAMP-elevating agents forskolin and IBMX decreased the chloride content of the cells by about 20-27%. Inducing a driving force for chloride by replacing extracellular chloride by nitrate resulted in a chloride efflux that was significantly increased in the presence of forskolin and IBMX. This study shows that X-ray microanalysis and MQAE fluorescence are adequate and comparable methods for measuring cAMP-dependent chloride transport in individual cells.
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