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Showing papers on "Cystic fibrosis published in 1993"


Journal ArticleDOI
02 Jul 1993-Cell
TL;DR: Cystic fibrosis is a regulated Cl- channel, for which structure-function relationships have begun to be established, and insight into the functions of individual domains has come from a number of studies.

1,446 citations


Journal ArticleDOI
TL;DR: Overall, patients with cystic fibrosis are living much longer than in the past but still have chronic pulmonary infections and other medical complications related to their disease, including diabetes, intestinal obstruction, cirrhosis, hemoptysis, and pneumothorax.

887 citations


Journal ArticleDOI
22 Oct 1993-Cell
TL;DR: A E1-deficient adenovirus, encoding CFTR, was administered to a defined area of nasal airway epithelium of three individuals with CF, and there was a decrease in the elevated basal transepithelial voltage, and the normal response to a cAMP agonist was restored.

721 citations


Journal ArticleDOI
TL;DR: AAV vectors do efficiently promote in vivo gene transfer to the airway epithelium which is stable over several months and indicates that AAV-CFTR vectors could potentially be very useful for gene therapy.
Abstract: Adeno-associated virus (AAV) vectors expressing the normal cystic fibrosis transmembrane conductance regulator (CFTR) cDNA complement the cystic fibrosis (CF) defect in vitro. Unlike other DNA virus vectors, AAV is a stably integrating virus, which could make possible long-term in vivo complementation of the CF defect in the airway epithelium. We report AAV-CFTR gene transfer and expression after infection of primary CF nasal polyp cells and after in vivo delivery of AAV-CFTR vector to one lobe of the rabbit lung through a fiberoptic bronchoscope. In the rabbit, vector DNA could be detected in the infected lobe up to 6 months after administration. A 26-amino acid polypeptide sequence unique to the recombinant AAV-CFTR protein was used to generate both oligonucleotide probes and a polyclonal antibody which allowed the unambiguous identification of vector RNA and CFTR protein expression. With these reagents, CFTR RNA and protein were detected in the airway epithelium of the infected lobe for up to 6 months after vector administration. AAV vectors do, therefore, efficiently promote in vivo gene transfer to the airway epithelium which is stable over several months. These findings indicate that AAV-CFTR vectors could potentially be very useful for gene therapy.

563 citations


Journal ArticleDOI
TL;DR: An inverse relationship between the length of the polythymidine tract at the exon 9 splice branch/acceptor site and the proportion of exon9− CFTR mRNA transcripts is found and strongly indicates a genetic basis in vivo modulating post–transcriptional processing of CFTR transcripts.
Abstract: Variable in-frame skipping of exon 9 in cystic fibrosis transmembrane conductance regulator (CFTR) mRNA transcripts (exon 9-) occurs in the respiratory epithelium. To explore the genetic basis of this event, we evaluated respiratory epithelial cells and blood leukocytes from 124 individuals (38 with cystic fibrosis (CF), 86 without CF). We found an inverse relationship between the length of the polythymidine tract at the exon 9 splice branch/acceptor site and the proportion of exon 9- CFTR mRNA transcripts. These results strongly indicate a genetic basis in vivo modulating post-transcriptional processing of CFTR mRNA transcripts.

494 citations


Journal ArticleDOI
18 Mar 1993-Nature
TL;DR: The use of liposomes is reported to deliver a CFTR expression plasmid to epithelia of the airway and to alveoli deep in the lung, leading to the correction of the ion conductance defects found in the trachea of transgenic (cf/cf) mice, illustrating the feasibility of gene therapy for the pulmonary aspects of CF in humans.
Abstract: CYSTIC fibrosis (CF) is a lethal inherited disorder affecting about 1 in 2,000 Caucasians. The major cause of morbidity is permanent lung damage resulting from ion transport abnormalities in airway epithelia that lead to mucus accumulation and bacterial colonization. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene1 that encodes a cyclic-AMP-regulated chloride channel2,3. Cyclic-AMP-regulated chloride conductances are altered in airway epithelia from CF patients4–6, suggesting that the functional expression of CFTR in the airways of CF patients may be a strategy for treatment. Transgenic mice7–9 with a disrupted cftr gene are appropriate for testing gene therapy protocols. Here we report the use of liposomes to deliver a CFTR expression plasmid to epithelia of the airway and to alveoli deep in the lung, leading to the correction of the ion conductance defects found in the trachea of transgenic (cf/cf) mice. These studies illustrate the feasibility of gene therapy for the pulmonary aspects of CF in humans.

483 citations


Journal ArticleDOI
11 Mar 1993-Nature
TL;DR: The results explain the quantitative decrease in macroscopic Cl- current, and suggest that R117, R334 and R347 contribute to the pore of the CFTR Cl- channel, and are suggested to have implications for the understanding of cystic fibrosis.
Abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-regulated Cl- channel located in the apical membrane of epithelia. Although cystic fibrosis (CF) is caused by mutations in a single gene encoding CFTR, the disease has a variable clinical phenotype. The most common mutation associated with cystic fibrosis, deletion of a phenylalanine at position 508 (frequency, 67%), is associated with severe disease. But some missense mutations, for example ones in which arginine is replaced by histidine at residue at 117 (R117H; 0.8%), tryptophan at 334 (0.4%), or proline at 347 (0.5%), are associated with milder disease. These missense mutations affect basic residues located at the external end of the second (M2) and in the sixth (M6) putative membrane-spanning sequences. Here we report that, when expressed in heterologous epithelial cells, all three mutants were correctly processed and generated cyclic AMP-regulated apical Cl- currents. Although the macroscopic current properties were normal, the amount of current was reduced. Patch-clamp analysis revealed that all three mutants had reduced single-channel conductances. In addition, R117H showed altered sensitivity to external pH and had altered single-channel kinetics. These results explain the quantitative decrease in macroscopic Cl- current, and suggest that R117, R334 and R347 contribute to the pore of the CFTR Cl- channel. Our results also suggest why R117H, R334W and R347P produce less severe clinical disease and have implications for our understanding of cystic fibrosis.

462 citations


Journal ArticleDOI
TL;DR: The short-term aerosol administration of a high dose of tobramycin in patients with clinically stable cystic fibrosis is an efficacious and safe treatment for endobronchial infection with P. aeruginosa.
Abstract: Background Direct aerosol delivery of aminoglycosides such as tobramycin to the lower airways of patients with cystic fibrosis may control infection with Pseudomonas aeruginosa and improve pulmonary function, with low systemic toxicity. We conducted a randomized crossover study to evaluate the safety and efficacy of aerosolized tobramycin in patients with cystic fibrosis and P. aeruginosa infections. Methods Seventy-one patients with stable pulmonary status were recruited from seven U.S. centers for the treatment of cystic fibrosis and randomly assigned to one of two crossover regimens. Group 1 received 600 mg of aerosolized tobramycin for 28 days, followed by half-strength physiologic saline (placebo) for two 28-day periods. Group 2 received placebo for 28 days, followed by tobramycin for two 28-day periods. Pulmonary function, the density of P. aeruginosa in sputum, ototoxicity, nephrotoxicity, and the emergence of tobramycin-resistant P. aeruginosa were monitored. Results In the first 28-day period, tr...

456 citations


Journal ArticleDOI

442 citations


Journal ArticleDOI
TL;DR: It is hypothesized that glutathione in respiratory epithelial lining fluid (ELF) in CF patients might be oxidized and/or diminished in amount compared with that in normal subjects and observed marked neutrophil-dominated inflammation in ELF inCF patients.
Abstract: Cystic fibrosis (CF), a disorder characterized by mutations of the CF transmembrane regulator gene, is characterized in the lung by chronic inflammation, leading to progressive damage to the airway epithelium, bronchiectasis, and chronic obstructive lung disease. One process contributing to the airway derangement is the chronic burden of oxidants released by inflammatory cells on the respiratory epithelial surface. With this background, we hypothesized that glutathione in respiratory epithelial lining fluid (ELF) in CF patients might be oxidized and/or diminished in amount compared with that in normal subjects. Recovery of ELF by bronchoalveolar lavage from young adults with CF (n = 21) and normal subjects (n = 25) demonstrated marked neutrophil-dominated inflammation in ELF in CF patients. As predicted, ELF in CF patients was characterized by a deficiency of glutathione (P 0.2). Unexpectedly, there was also a marked deficiency of reduced glutathione in plasma (P < 0.02); i.e., the glutathione "deficiency" observed in ELF in CF patients is not limited to the site of the inflammation but is systemic. Although the etiology of this generalized deficiency of extracellular glutathione is unknown, it is important in considering options for treating the concomitant and devastating lung pathology in this disorder.

384 citations


Journal ArticleDOI
TL;DR: Findings clarify the mechanism by which mutation causing delta F508 affects the intracellular trafficking of CFTR and suggest another function for hsp70 in ensuring quality control during the biosynthesis of plasma-membrane proteins.
Abstract: The most common cause of cystic fibrosis is deletion of Phe-508 (delta F508) from the cystic fibrosis transmembrane conductance regulator (CFTR). Previous studies have suggested that delta F508 CFTR is an unstable protein that retains a pattern of glycosylation specific to the endoplasmic reticulum. This report examines the mechanism responsible for the mislocalization of delta F508 CFTR in a human cystic fibrosis epithelial cell line overexpressing recombinant CFTR by virtue of adenovirus-mediated gene transfer. Immunoelectron microscopy confirmed that wild-type CFTR is delivered to the plasma membrane of these cells and that delta F508 CFTR is retained in the endoplasmic reticulum. Pulse-chase studies showed that newly synthesized CFTR complexes with the chaperone hsp70. The wild-type protein dissociates from hsp70 before its transport to the Golgi, and the protein is subsequently degraded in lysosomes. By contrast, the complex formed between delta F508 CFTR and hsp70 is retained in the endoplasmic reticulum and delta F508 CFTR is rapidly degraded in a pre-Golgi nonlysosomal compartment. Thus, hsp70 discriminates between the normal form of CFTR and the form of the protein that most commonly causes cystic fibrosis (delta F508). These findings clarify the mechanism by which mutation causing delta F508 affects the intracellular trafficking of CFTR and suggest another function for hsp70 in ensuring quality control during the biosynthesis of plasma-membrane proteins.

Journal ArticleDOI
TL;DR: It is concluded that adenovirus-mediated gene transfer into the lungs of baboons is associated with development of alveolar inflammation at high doses of virus.
Abstract: In preparation for human trials of gene therapy for cystic fibrosis (CF), we performed a preclinical study of gene transfer into the lungs of baboons. Recombinant adenovirus vectors containing expression cassettes for human cystic fibrosis transmembrane conductance regulator (CFTR) and Escherichia coli β-galactosidase (lacZ) were instilled through a bronchoscope into limited regions of lung in 14 baboons. A detailed accounting of the extent, distribution, and duration of gene expression is contained in a companion article (Engelhardt et al., 1993b). In this article, we report the results of toxicity studies in which clinical laboratory tests, chest radiographs, and necropsy studies were used to detect adverse effects. The only adverse effect noted was a mononuclear cell inflammatory response within the alveolar compartment of animals receiving doses of virus that were required to induce detectable gene expression. Minimal inflammation was seen at 107 and 108 pfu/ml, but at 109 and more prominentl...

Journal ArticleDOI
TL;DR: The apical localization of CFTR in bile duct cells suggests a model explaining how the CFTR-associated Cl- channel contributes to normal biliary secretion and suggests that if CFTR expression could be promoted in intrahepatic duct cells by somatic gene therapy, this might prevent the occurrence of liver disease in CF.

Journal ArticleDOI
TL;DR: It is suggested that IL-8 accounts, at least in part, for neutrophil recruitment into airways of patients with these diseases.
Abstract: Sputum from patients with cystic fibrosis, bronchiectasis, and chronic bronchitis contains neutrophils and neutrophil proteases, which have been implicated in the pathophysiology of mucus hypersecretion in airways. We asked whether interleukin-8 (IL-8), a potent neutrophil chemoattractant, might be involved in recruiting neutrophils into airways of patients with cystic fibrosis, bronchiectasis, and chronic bronchitis. We found significant neutrophil chemotactic activity in sputum obtained from these patients. The IL-8 concentrations that we measured in sputum of patients with cystic fibrosis (7.1 +/- 1.0 x 10(-9) M, mean +/- SE), bronchiectasis (9.6 +/- 2.9 x 10(-9) M), and chronic bronchitis (2.8 +/- 1.0 x 10(-9) M) have been reported to cause significant chemotaxis in vitro and in airways in vivo, whereas concentrations measured in induced sputum from healthy subjects (1.1 +/- 0.3 x 10(-10) M) do not. A monoclonal antibody to IL-8 significantly inhibited the chemotactic activity in patients' sputum by 7...

Journal ArticleDOI
TL;DR: A replication deficient recombinant adenovirus can transfer an exogenous gene to all major categories of airway epithelial cells in vivo, suggesting that adenvirus vectors may be an efficient strategy for in vivo gene transfer in airway disorders such as cystic fibrosis.
Abstract: A variety of pulmonary disorders, including cystic fibrosis, are potentially amenable to treatment in which a therapeutic gene is directly transferred to the bronchial epithelium. This is difficult to accomplish because the majority of airway epithelial cells replicate slowly and/or are terminally differentiated. Adenovirus vectors may circumvent this problem, since they do not require target cell proliferation to express exogenous genes. To evaluate the diversity of airway epithelial cell targets for in vivo adenovirus-directed gene transfer, a replication deficient recombinant adenovirus containing the Escherichia coli lacZ (beta-galactosidase [beta-gal]) gene (Ad.RSV beta gal) was used to infect lungs of cotton rats. In contrast to uninfected animals, intratracheal Ad.RSV beta gal administration resulted in beta-gal activity in lung lysate and cytochemical staining in all cell types forming the airway epithelium. The expression of the exogenous gene was dose-dependent, and the distribution of the beta-gal positive airway epithelial cells in Ad.RSV beta gal-infected animals was similar to the normal cell differential of the control animals. Thus, a replication deficient recombinant adenovirus can transfer an exogenous gene to all major categories of airway epithelial cells in vivo, suggesting that adenovirus vectors may be an efficient strategy for in vivo gene transfer in airway disorders such as cystic fibrosis.

Journal ArticleDOI
TL;DR: Using gene targeting in embryonic stem cells to introduce an HPRT mini–gene into the coding sequence of the murine cystic fibrosis gene (cftr) introduces a termination codon in frame with the cftr coding sequence to terminate prematurely the CFTR protein within the first nucleotide binding domain.
Abstract: We have used gene targeting in embryonic stem cells to introduce an HPRT mini–gene into the coding sequence of the murine cystic fibrosis gene (cftr). This insertion introduces a termination codon in frame with the cftr coding sequence to terminate prematurely the CFTR protein within the first nucleotide binding domain. Animals homozygous for the cftr disruption fail to thrive and display a range of symptoms including meconium ileus, distal intestinal obstructions, gastrointestinal mucus accumulation and blockage of pancreatic ducts. The animals also show lacrimal gland pathology. Tracheal and caecal transepithelial current measurements demonstrate the lack of a cAMP activatable Cl−channel. These animals will prove useful for the evaluation of new therapeutic drugs and gene therapy strategies.

Journal ArticleDOI
TL;DR: The production of the major neutrophil chemotactic cytokine IL-8 by alveolar macrophages or other cells could be of great importance in the pathology of acute lung disease, but its role in the persistent lung inflammation characteristic of CF has not been evaluated.
Abstract: Concurrent pulmonary inflammation and neutrophil infiltration are characteristic of children with cystic fibrosis (CF). The production of the major neutrophil chemotactic cytokine IL-8 by alveolar macrophages or other cells could be of great importance in the pathology of acute lung disease, but its role in the persistent lung inflammation characteristic of CF has not been evaluated. In this study, we have measured, by ELISA, the concentration of IL-8 in sputum, bronchoalveolar lavage, and sera specimens obtained from children with CF. For comparison, IL-8 in bronchoalveolar lavage obtained from asthmatic patients and from non-CF children with or without lung infection and in sera from age-matched controls was measured. High levels of IL-8 were measured in sputum (mean = 2952 pM) and in bronchoalveolar lavage (mean = 6624 pM) from CF patients. In both cases, there was a significant correlation between clinical status (Schwach-man score) and IL-8 levels. This was not true for IL-8 levels measured in sera, which nevertheless were significantly higher in CF patients (p = 0.0001) than in normal controls in the over-10-y age group.

Journal ArticleDOI
TL;DR: It is suggested that recombinant adenovirus can be used to transfer genes efficiently to the lung of nonhuman primates and that therapeutic strategies of cystic fibrosis may require repetitive administration with current vectors.
Abstract: We have evaluated the biological efficacy of E1-deleted adenoviruses in baboons for lung-directed gene therapy of cystic fibrosis (CF). The experimental design attempted to simulate a phase I clinical trial with animals receiving a single dose of virus to an isolated pulmonary segment. A total of 14 animals divided into four groups, each of which received escalating doses of virus, were used. Individual animals were necropsied 4 and 21 days after gene transfer and tissues were carefully surveyed for gene expression. Expression of the transgene was localized primarily to the area into which it was infused; the efficiency of recombinant gene expression and the abundance of transgene sequences were proportional to dose and both diminished with time. Transgene expression was found predominantly in alveolar cells with patches of expression in the proximal and distal airway. Analysis of adenoviral protein expression within transgene-expressing cells revealed infrequent expression of the E2a gene and no detectable expression of late genes (i.e., fiber protein). These results suggest that recombinant adenovirus can be used to transfer genes efficiently to the lung of nonhuman primates and that therapeutic strategies of cystic fibrosis may require repetitive administration with current vectors.

Journal ArticleDOI
TL;DR: Surprisingly low multiplicities of infection were sufficient to generate CFTR Cl- current across a CF epithelial monolayer in vitro, suggesting that Ad2/CFTR-1 should be suitable for CF gene therapy.
Abstract: A new adenovirus-based vector (Ad2/CFTR-1) has been constructed in which the cDNA encoding the cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis (CF) gene product, replaces the early region 1 coding sequences, E1a and E1b. The virus retains the E3 region. Ad2/CFTR-1 and a related construct encoding β-galactosidase replicate in human 293 cells which provide E1 gene functions in trans. Replication of these recombinant viruses was not detected in a variety of other cells, although very limited viral DNA synthesis and transcription from the E4 and L5 regions could be measured. These E1-deletion vectors were also deficient in cellular transformation, shut-off of host cell protein synthesis, and production of cytopathic effects, even at high multiplicities of infection. Ad2/CFTR-1 produced CFTR protein in a variety of cells including airway epithelia from CF patients. Expression of functional CFTR protein in a CF airway epithelial monolayer was detected by correction of th...

Journal ArticleDOI
TL;DR: Results show that phosphorylation-regulated Cl− channel activity of ΔF508-CFTR is similar to that of wild-type CFTR, suggesting that this Common mutation does not result in a significant alteration in CFTR function.
Abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-regulated Cl- channel. In most mammalian cells, the functional consequences of the most common CF mutation, delta F508-CFTR, cannot be assessed as the mutant protein undergoes biosynthetic arrest. However, function can be studied in the baculovirus-insect cell expression system where delta F508-CFTR does not appear to undergo such arrest. Our results show that phosphorylation-regulated Cl- channel activity of delta F508-CFTR is similar to that of wild-type CFTR. This observation was confirmed in comparative studies of purified delta F508-CFTR and CFTR reconstituted in planar lipid bilayers. Therefore, we suggest that this common mutation does not result in a significant alteration in CFTR function.

Journal ArticleDOI
TL;DR: Findings suggest epithelia of the lung, that contain very little CFTR mRNA in the adult, express high levels of CFTR RNA in the foetus, since the lung is the major site of pathology and morbidity in CF, and these findings have implications for treatment.
Abstract: In order to examine the onset of the cystic fibrosis (CF) disease process, the expression of the cystic fibrosis gene (CFTR) has been examined in mid-trimester human foetal tissues by in situ hybridization. CFTR mRNA was detected in the epithelia of pancreatic ducts, small intestine, colon, genital ducts, lung and trachea. The majority of these sites of CFTR expression in the foetus are similar to those seen in adult tissues. However, epithelia of the lung, that contain very little CFTR mRNA in the adult, express high levels of CFTR mRNA in the foetus. Since the lung is the major site of pathology and morbidity in CF these findings have implications for treatment.

Journal ArticleDOI
TL;DR: It is suggested that it may be feasible to prevent CF liver disease by genetically reconstituting CFTR expression in the biliary tract, using an approach that is clinically feasible.
Abstract: Cystic fibrosis (CF) is an inherited disease of epithelial cell ion transport that is associated with pathology in multiple organ systems, including lung, pancreas, and liver. As treatment of the pulmonary manifestations of CF has improved, management of CF liver disease has become increasingly important in adult patients. This report describes an approach for treating CF liver disease by somatic gene transfer. In situ hybridization and immunocytochemistry analysis of rat liver sections indicated that the endogenous CFTR (cystic fibrosis transmembrane conductance regulator) gene is primarily expressed in the intrahepatic biliary epithelial cells. To specifically target recombinant genes to the biliary epithelium in vivo, recombinant adenoviruses expressing lacZ or human CFTR were infused retrograde into the biliary tract through the common bile duct. Conditions were established for achieving recombinant gene expression in virtually all cells of the intrahepatic bile ducts in vivo. Expression persisted in the smaller bile ducts for the duration of the experiment, which was 21 days. These studies suggest that it may be feasible to prevent CF liver disease by genetically reconstituting CFTR expression in the biliary tract, using an approach that is clinically feasible.

Journal ArticleDOI
TL;DR: It is concluded that the 3849 + 10 kb C-->T mutation is associated with a mild type of CF, similar to other Ashkenazi Jews.

Journal ArticleDOI
TL;DR: An additional mouse model for CF has been generated that should prove useful for the understanding of the pathogenesis and the development of treatments for CF.
Abstract: To develop an animal model for cystic fibrosis (CF), targeted gene disruption in embryonic stem (ES) cells was used to generate a duplication of exon 3 (cftrm1Bay allele) of the mouse CF gene. ES cells containing this mutation were used to generate chimeric animals that transmitted the mutant allele through the germline. Homozygous mutant animals display a severe phenotype, with approximately 40% dying within 1 week from intestinal obstruction. RNAase protection analysis of the cftrm1Bay allele did not detect any normal mRNA (< 1-2% of wild-type) in mutant animals. Pathologic changes in the intestines from mutant mice included mucus accumulation in the crypts and intestinal lumen, dilatation of the bases of the crypts, enlargement of goblet cells, and the presence of concretions in the crypts or between the villi. Changes were also present in the mucosal glands of the pharynx and the minor sublingual glands, where dilatation of acini and accumulation of eosinophilic material were evident. Atrophy of acinar cells that may be secondary to nutritional deficiency and mild inflammation in the main pancreatic duct were present in the pancreas of mutant animals. No changes were noted in the lung, trachea, liver, or male reproductive tract of mutant animals, and mutant males were fertile. Homozygous mutant mice showed defects in cAMP-mediated ion transport both in ileum and in cultured fetal tracheal explants. Thus, an additional mouse model for CF has been generated that should prove useful for the understanding of the pathogenesis and the development of treatments for CF.

Journal Article
TL;DR: It is concluded that, in the presence of established treatment for cystic fibrosis lung disease, nebulized amiloride offers no additional clinical benefit.
Abstract: In cystic fibrosis (CF) airway epithelial sodium absorption is increased 2-3 fold. Since sodium absorption is inhibited by the sodium channel blocker amiloride, our aim was to assess its therapeutic benefit in cystic fibrosis. A randomized, double-blind, placebo-controlled, cross-over trial of nebulized amiloride was performed in 23 patients with cystic fibrosis. Amiloride or placebo was administered four times daily for two six month periods. Existing treatment was continued, and any infective exacerbations treated in the usual way. Fourteen patients completed the study. No significant changes occurred in forced expiratory volume in one second, forced vital capacity, oxygen saturation, body weight, sputum volume, culture and rheology, serum urea, and electrolytes, white cell count and erythrocyte sedimentation rate during either treatment period. The frequency of infective exacerbations was also not different in either treatment period. We were thus unable to confirm the benefit shown in the only other clinical trial of nebulized amiloride in cystic fibrosis and conclude that, in the presence of established treatment for cystic fibrosis lung disease, nebulized amiloride offers no additional clinical benefit.

Journal ArticleDOI
TL;DR: Genotypic and phenotypic characterization of a delta F508 homozygote cell line derived from luminal epithelium in the trachea are reported, which shows that they express keratin, indicating epithelial cell origin, and that a calcium-dependent cell adhesion molecule is present at plasma membrane junctions between cells.
Abstract: The development of transformed human airway epithelial cell lines has been important in advancing the understanding of the biochemical and genetic mechanisms underlying the cystic fibrosis (CF) defect. Since the most common mutation associated with CF is a phenylalanine deletion at position 508 (delta F508) in the CF transmembrane conductance regulator (CFTR) gene, a transformed airway epithelial cell line homozygous for this mutation will be important for determining the biologic significance of this mutation in the airways. We report the genotypic and phenotypic characterization of a delta F508 homozygote cell line derived from luminal epithelium in the trachea. The cells were transformed with a plasmid containing an origin of replication defective SV40 genome and have progressed through crisis. Immunocytochemical characterization of the cells shows that they express keratin, indicating epithelial cell origin, and that a calcium-dependent cell adhesion molecule, cellCAM 120/80, is present at plasma membrane junctions between cells. Electrophysiologically, the cells show no cAMP-dependent Cl transport. However, after treatment with the calcium ionophore, ionomycin, cells secrete Cl, albeit at a lower level than that observed in normal cells. Genetically, the cells express CFTR mRNA as determined by polymerase chain reaction amplification and CFTR protein as determined by Western hybridization analysis. Karyotypic analysis shows that 70% of the cells contain two copies of chromosome 7.

Journal ArticleDOI
TL;DR: In this paper, the expression of CFTR in human fetal tissues at different gestational ages using in situ hybridization to detect CFTR mRNA was found in less differentiated cells of endodermal origin, with the highest levels being found in specific areas of the developing pancreas, liver, gall bladder and intestine, with lower but significant levels in lung and trachea.
Abstract: An improved understanding of the expression of the cystic fibrosis gene (CFTR) will assist our approach to preventing the organ damage caused by cystic fibrosis (CF). We have studied the expression of CFTR in human fetal tissues at different gestational ages using in situ hybridization to detect CFTR mRNA. CFTR was principally expressed in less differentiated cells of endodermal origin. The highest levels were seen in specific areas of the developing pancreas, liver, gall bladder and intestine, with lower but significant levels in lung and trachea. Expression was also seen in reproductive tissues, such as epididymis and third trimester uterus and fallopian tubes, and in addition, sweat and salivary glands. No detection of CFTR mRNA was found in many other relevant tissues. The detection of CFTR transcript in these organs is consistent with the clinical manifestations of CF and the function of CFTR as a chloride channel early in development. The localization and levels of expression described have implications regarding the pathogenesis of organ damage and the potential gains that can be achieved by early therapy in the disease.

Journal Article
TL;DR: The data suggest that in airway tissues, CFTR could be involved in intracellular processes of the mucus exocytosis in submucosal secretory glands.
Abstract: Cystic fibrosis (CF) is caused by mutations in the gene coding for the CF transmembrane conductance regulator (CFTR). From human normal tracheal submucosal gland cells in culture, we identified endogenous CFTR as a 170 kDa protein, consistent with that of fully glycosylated, mature CFTR molecule. This observation led to the hypothesis that airway secretory glands could be an important site for the CFTR expression. Using anti-human CFTR polyclonal and monoclonal antibodies, we examined the cellular and subcellular localization of the CFTR protein in airway submucosal glands from human and bovine tracheal tissues as well as in tracheal gland cell cultures. In human tracheal tissue, CFTR immunolabelling was present along both the apical and basolateral plasma membranes of glandular mucous cells. In contrast, CFTR was associated with the secretory granules of glandular serous cells. Using immunogold electron microscopy, we demonstrated that CFTR protein was more specifically associated with the membrane of serous cell secretory granules. In bovine tracheal tissue CFTR labelling was also identified in the secretory granules of glandular serous cells. In contrast, when bovine and human tracheal gland cells were cultured, no mature secretory granules were present, but a predominantly intracytoplasmic distribution of CFTR was observed. Our data thus suggest that in airway tissues, CFTR could be involved in intracellular processes of the mucus exocytosis in submucosal secretory glands.

Journal ArticleDOI
TL;DR: The study aimed to detect early liver disease, that is multilobular cirrhosis and its complications, with a view to optimal introduction of treatment with ursodeoxycholic acid as this drug shows promise for preventing or stabilising the cirrhotic process.
Abstract: Experience gained from liver studies in 450 patients with cystic fibrosis, seen in a 38 year period from 1964 to 1992, is surveyed. Of these, 31 (7%) showed findings that indicated multilobular cirrhosis. There was a slight but not significant male predominance: 19 males against 12 females. Liver disease had its onset during childhood in most cases. The natural course of liver disease and of cirrhosis is protracted. All patients were routinely evaluated by way of: (i) clinical examination, (ii) biochemical studies and specifically estimation of transaminases and gamma glutamyltransferase, and (iii) liver imaging, ultrasonography, and computed tomography. The study aimed to detect early liver disease, that is multilobular cirrhosis and its complications, with a view to optimal introduction of treatment with ursodeoxycholic acid as this drug shows promise for preventing or stabilising the cirrhotic process. Effects of surgical treatment on portal hypertension are surveyed. These include portacaval shunting, partial splenectomy (considered the procedure of choice), liver transplant in the event of liver failure, or a triple transplant (liver, lungs, and heart) if necessary. One triple transplant was successfully performed in a boy of 10 years with a 2 year follow up.