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- Nilsson, Harriet
(författare)
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Studies of Tight Junctions and Airway Surface Liquid in Airway Epithelium with Relevance to Cystic Fibrosis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cystic fibrosis (CF) is a multi-organ autosomal recessive disease of fluid-transporting epithelia, due to a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is a cAMP-regulated Cl-channel involved in various regulatory processes. Salt and water transport depend on CFTR and the epithelial sodium channel (ENaC), operating in concert with the paracellular pathway through the tight junctions (TJ). The ionic composition of the ASL has been assumed to be altered in CF, resulting in a fatal accumulation of viscous mucus in the airways. ASL samples were collected from tracheal and nasal fluid in normal and transgenic CF mice and from the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a CF human bronchial cell line (CFBE41o-). Analysis of the elemental content of the ASL was performed by X-ray microanalysis. The ASL contained more Na and Cl in CFTR-deficient or DF508-CFTR-containing cells than in control cells with wild- type CFTR. The relation between osmolarity and TJ permeability was examined by the addition of salt or sugar (295-700 mOsm) to 16HBE14o- cells, where the integrity of TJ was evaluated by transepithelial electrical resistance (TEER) measurements. Studies of interaction between the activity of CFTR, TJ and cytoskeleton were performed in CFBE41o-, plasmid corrected CFBE41o- (CFBE41o pCep4), and 16HBE14o- cells exposed to an inhibitor of CFTR (CFTRinh-172). The TJ were investigated by determining the paracellular permeability to lanthanum ions or with [14C] mannitol. Cytoskeletal changes were evaluated by immunofluorescence. Hyperosmotic stress resulted in opening of TJ. Inhalation of hypertonic salt or sugar solutions may open TJ, leading to enhanced paracellular water transport and increased ASL volume, diluted mucus and enhanced mucociliary clearance. This may explain the beneficial effect of this treatment for CF-patients. In healthy airway epithelial cells, inhibition of CFTR by CFTRinh-172 resulted in an increased TEER, whereas stimulation of CFTR by IBMX/forskolin caused a decrease. The paracellular permeability was inversely proportional to TEER. Immunofluorescence revealed a disorganization of cytoskeletal proteins in CF-cells. These results point toward a possible interaction between the activity of CFTR and TJ protein complex, presumably via the cytoskeleton.
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| 2. |
- Kozlova, Inna, 1965-
(författare)
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Studies on Airway Surface Liquid in Connection with Cystic Fibrosis
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cystic fibrosis (CF) is one of the most common fatal inherited diseases, most prevalent among Caucasians. CF is caused by a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), which helps to create sweat, digestive juices, and airway surface liquid (ASL).The airways are covered with a thin layer of fluid, the airway surface liquid, in which the cilia bathe. Defective or absent CFTR leads to a defective water and ion transport in the epithelial cells, which results in viscous mucus, defective ciliary clearance, bacterial inflammation and tissue damage. The volume and composition of ASL are important in the pathogenesis of cystic fibrosis and it is therefore relevant to determine its composition. However, there are a number of difficulties in determining the ionic composition of the ASL due to its small volume. Literature data vary from very hypotonic to markedly hypertonic. These controversial data inspired the development of a simple method for determining the elemental composition of the ASL in different animal species and humans. Two techniques were developed to determine the composition of ASL, from which indirect information on chloride transport in airway epithelium can be obtained. In the first method, tissue is removed from the animals under anesthesia, frozen and analyzed in the frozen-hydrated state. In the second method, the ASL is collected with small dextran (Sephadex) beads; the dried beads are then analyzed by X-ray microanalysis. The Sephadex-bead method appears more accurate compared to the frozen-hydrated samples. Both methods were applied to collect tracheal and/or nasal fluid in pigs, normal and transgenic cystic fibrosis mice, the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a cystic fibrosis human bronchial cell line (CFBE41o-), and finally nasal fluid in healthy and diseased subjects. The ionic composition of the ASL was isotonic both in pigs and healthy human subjects. CF patients had much higher levels of Na and Cl ions than healthy subjects. The ASL under control conditions was hypotonic in mice and cell cultures, whereas the concentrations of Na and Cl ions in the species with the ΔF508 mutation or absent CFTR were significantly higher than in the corresponding controls. It was also demonstrated that the ionic composition of the ASL can be influenced by pharmacological treatment. The study confirms earlier findings that CFTR also is involved in bicarbonate transport. Mist tent therapy has been tested in the study of a treatment for CF patients, in order to hydrate the viscous mucus. But the effect of mist tent therapy on ion concentrations in the ASL appeared to be short-lived, although no patients became chronically colonized with pseudomonads while on nocturnal mist tent therapy.
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| 4. |
- Fabian, ID, et al.
(författare)
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Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries
- 2021
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Ingår i: The British journal of ophthalmology. - : BMJ. - 1468-2079 .- 0007-1161. ; 105:10, s. 1435-1443
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Tidskriftsartikel (refereegranskat)abstract
- The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe.MethodsA cross-sectional analysis including 518 treatment-naïve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naïve patients with retinoblastoma residing in 43 African countries.ResultsCapture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI −12.4 to −5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease.ConclusionsFewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral.
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