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Cystic fibrosis transmembrane conductance regulator (CFTR) activity in nasal epithelial cells from cystic fibrosis patients with severe genotypes.

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 deltaF508-CFTR (i.e. CTFR lacking residue Phe-508). The others were deltaF508-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 deltaF508/deltaF508 patients and one deltaF508/3659delC 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.

Adolescent↗

Cystic fibrosis: the effect of medium from cultured cystic fibrosis fibroblasts on ATPase activity.

Culture medium from fibroblasts of cystic fibrosis patients and controls was examined for the ability to inhibit (calcium plus magnesium)-activated ATPase and (sodium plus potassium)-activated ATPase. The ATPase systems used were both a solubilised preparation from dog-fish and a membrane associated preparation from human erythrocyes. Contrary to other reports the medium from cystic fibrosis fibroblasts did not inhibit ATPase activity.

Adenosine Triphosphatases↗

Genetic characterisation of circulating fetal cells allows non-invasive prenatal diagnosis of cystic fibrosis.

OBJECTIVES: Cystic fibrosis (CF) is an autosomal recessive disease due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The purpose of this study was to develop a molecular method to characterise both paternal and maternal CFTR alleles in DNA from circulating fetal cells (CFCs) isolated by ISET (isolation by size of epithelial tumour/trophoblastic cells). METHODS: The molecular protocol was defined by developing the F508del mutation analysis and addressing it both to single trophoblastic cells, isolated by ISET and identified by short tandem repeats (STR) genotyping, and to pooled trophoblastic genomes, thus avoiding the risk of allele drop out (ADO). This protocol was validated in 100 leucocytes from F508del carriers and subsequently blindly applied to the blood (5 mL) of 12 pregnant women, at 11 to 13 weeks of gestation, whose offspring had a 1/4 risk of CF. Ten couples were carriers of F508del mutation, while two were carriers of unknown CFTR mutations. RESULTS: Results showed that one fetus was affected, seven were heterozygous carriers of a CFTR mutation, and four were healthy homozygotes. These findings were consistent with those obtained by chorionic villus sampling (CVS). CONCLUSION: Our data show that the ISET-CF approach affords reliable prenatal diagnosis (PND) of cystic fibrosis and is potentially applicable to pregnant women at risk of having an affected child, thus avoiding the risk of iatrogenic miscarriage.

Alleles↗

The 3120 +1G-->A splicing mutation in CFTR is common in Brazilian cystic fibrosis patients.

Cystic fibrosis patients from Rio de Janeiro, Brazil, were screened for mutations in exons 11 and 16 of the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a nonradioactive single-stranded conformational polymorphism (SSCP) analysis technique. This procedure was used to evaluate the undefined mutations in one or both alleles of 64 cystic fibrosis patients. Unusual SSCP profiles were investigated further by sequence analysis. Two patients were shown to carry the G542X mutation (exon 11) and five had the splicing mutation 3120+1G-->A(intron 16), one of them being homozygous for the mutation. This is the first report of the 3120+ IG-->A mutation in Brazil. where it appears to be a frequent disease-associated molecular alteration in the CFTR gene.

Brazil↗

Colonic strictures in patients with cystic fibrosis: results of a survey of 114 cystic fibrosis care centers in the United States.

We describe 15 cases of stricture of the colon requiring surgery in cystic fibrosis patients identified from a survey of 114 cystic fibrosis care centers in the United States. Patient ages ranged from 2 to 8 years, seven of the 15 patients were female. A history of meconium ileus was reported in nine of the 15 cases. Fibrosis of the submucosa was described in 14 surgical pathology reports. Pancreatic enzyme use history was available from 14 reports. All had taken delayed-release products for 6-96 months at average doses ranging from 6,700 to 29,100 units lipase/kg/meal, but only eight of them used products containing >20,000 units lipase per capsule prior to surgery.

Administration, Oral↗

The frequency of the delta F508 mutation in the cystic fibrosis genes of 71 unrelated South African cystic fibrosis patients.

The common delta F508 mutation is present in approximately 70% of mutant cystic fibrosis (CF) genes of European and North American populations. The frequency of the delta F508 mutation has been established for two groups of South African CF subjects. The mutation was found to be present in 82% and 53% of CF genes of white and coloured (i.e. of mixed ancestry) subjects respectively. These findings assist in providing appropriate counselling to individuals who have a family history of CF and in defining laboratory strategies for the establishment of an efficient genetic service for cystic fibrosis.

Cystic Fibrosis↗

Evidence for safety and efficacy of DOTAP cationic liposome mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis.

In cystic fibrosis (CF), mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene results in defective transepithelial ion transport, leading to life shortening inflammatory lung disease. Before lung studies, we tested the safety and efficacy of gene delivery to the nasal epithelium of CF patients using pCMV-CFTR-DOTAP cationic liposome complex. A single dose of 400 micrograms pCMV-CFTR:2.4 mg DOTAP was administered in a randomised, double-blinded fashion to the nasal epithelium of eight CF patients, with a further eight receiving buffer only. Patients were monitored for signs and symptoms for 2 weeks before treatment and 4 weeks after treatment. Inflammatory cells were quantified in a nasal biopsy taken 3 days after treatment. There was no evidence for excess nasal inflammation, circulating inflammatory markers or other adverse events ascribable to active treatment. Gene transfer and expression were assayed by the polymerase chain reaction. Transgene DNA was detected in seven of the eight treated patients up to 28 days after treatment and vector derived CFTR mRNA in two of the seven patients at +3 and +7 days. Transepithelial ion transport was assayed before and after treatment by nasal potential difference during drug perfusion and by SPQ fluorescence halide ion conductance. Partial, sustained correction of CFTR-related functional changes toward normal values were detected in two treated patients. The level of gene transfer and functional correction were comparable to those reported previously using adenoviral vectors or another DNA-liposome complex, but here were sustained and uncompromised by false positives. These results justify further studies with pCMV-CFTR-DOTAP aimed at treating CF lung disease.

Adult↗

Impaired cell volume regulation in intestinal crypt epithelia of cystic fibrosis mice.

Cystic fibrosis is a disease characterized by abnormalities in the epithelia of the lungs, intestine, salivary and sweat glands, liver, and reproductive systems, often as a result of inadequate hydration of their secretions. The primary defect in cystic fibrosis is the altered activity of a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR) channel. However, it is not clear how a defect in the CFTR Cl- channel function leads to the observed pathological changes. Although much is known about the structural properties and regulation of the CFTR, little is known of its relationship to cellular functions other than the cAMP-dependent Cl- secretion. Here we report that cell volume regulation after hypotonic challenge is also defective in intestinal crypt epithelial cells isolated from CFTR -/- mutant mice. Moreover, the impairment of the regulatory volume decrease in CFTR -/- crypts appears to be related to the inability of a K+ conductance to provide a pathway for the exit of this cation during the volume adjustments. This provides evidence that the lack of CFTR protein may have additional consequences for the cellular function other than the abnormal cAMP-mediated Cl- secretion.

Animals↗

Bone mineral density and body composition in adult patients with cystic fibrosis.

BACKGROUND: Cystic fibrosis is a multisystem disease characterised by chronic pulmonary sepsis and malnutrition. To ascertain whether osteoporosis is a feature of cystic fibrosis in adult patients, total body and regional bone mineral density (BMD) was measured in a group of eight men and eight women aged 17-42 years. METHODS: Total body and regional BMD (lumbar spine L2-L4, femoral neck, trochanteric, and Ward's triangle), as well as total body fat and lean mass, were measured by dual energy x ray absorptiometry. A range of biochemical, lifestyle, and anthropometric variables was also assessed. RESULTS: Patients with cystic fibrosis had significantly reduced bone density at all sites compared with normal young adults. The mean reductions ranged from 7% at Ward's triangle to 13% at the trochanter. Body mass index (BMI) was positively correlated with BMD at four sites and disease severity negatively correlated with BMD at two sites. Other biochemical and anthropometric variables were not predictive of bone density. Total body fat mass was reduced by 30% compared with normal young adults. CONCLUSIONS: Bone density is decreased in adult patients with cystic fibrosis and BMI and disease severity are independent predictors of bone density.

Adolescent↗

Altered chloride ion channel kinetics associated with the delta F508 cystic fibrosis mutation.

Cystic fibrosis is associated with a defect in epithelial chloride ion transport which is caused by mutations in a membrane protein called CFTR (cystic fibrosis transmembrane conductance regulator). Heterologous expression of CFTR produces cyclicAMP-sensitive Cl(-)-channel activity. Deletion of phenylalanine at amino-acid position 508 in CFTR (delta F508 CFTR) is the most common mutation in cystic fibrosis. It has been proposed that this mutation prevents glycoprotein maturation and its transport to its normal cellular location. We have expressed both CFTR and delta F508 CFTR in Vero cells using recombinant vaccinia virus. Although far less delta F508 CFTR reached the plasma membrane than normal CFTR, sufficient delta F508 CFTR was expressed at the plasma membrane to permit functional analysis. delta F508 CFTR expression induced a reduced activity of the cAMP-activated Cl- channel, with conductance, anion selectivity and open-time kinetics similar to those of CFTR, but with much greater closed times, resulting in a large decrease of open probability. The delta F508 mutation thus seems to have two major consequences, an abnormal translocation of the CFTR protein which limits membrane insertion, and an abnormal function in mediating Cl- transport.

Cells, Cultured↗

Aerosol alpha 1-antitrypsin treatment for cystic fibrosis.

In cystic fibrosis neutrophil-dominated inflammation on the respiratory epithelial surface results in a chronic epithelial burden of the destructive enzyme, neutrophil elastase. alpha 1-antitrypsin (alpha 1AT), the main inhibitor of neutrophil elastase in lung, was given in aerosol form to 12 cystic fibrosis patients. It suppressed neutrophil elastase in the respiratory epithelial lining fluid (ELF) and restored the ELF anti-neutrophil elastase capacity when ELF alpha 1AT reached 8 mumol/l. This treatment also reversed the inhibitory effect of cystic fibrosis ELF on pseudomonas killing by neutrophils, which suggests that it may augment host defence in cystic fibrosis.

Adult↗

Investigation of aminoglycoside nephrotoxicity in cystic fibrosis patients.

Cystic fibrosis patients are a special risk group for nephrotoxic effects of amino-glycosides (AG). The traditional methods of assessing renal damage are very insensitive, and toxicity is not detected until serious functional damage is evident. The aims of the present study were to monitor early markers of nephrotoxicity in cystic fibrosis patients treated with gentamicin. Urinary excretion of beta-N-acetylglucosaminase (beta-NAG, a lysosomal enzyme) and low molecular weight proteins as identified on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were prospectively studied in cystic fibrosis outpatients and inpatients. Urinary excretions of beta-NAG and low molecular weight proteins were normal in cystic fibrosis patients not being treated with gentamicin. All patients being treated with intravenous gentamicin (average dose, 2.5 g over 9 days) showed markedly elevated urinary excretion of beta-NAG. SDS-PAGE of serial urine samples from CF patients during intravenous AG therapy showed increasing excretion of low molecular weight proteins. Protein excretion profiles from control subjects showed no change over equivalent time periods. CF patients receiving nebulized AG did not show altered protein excretion. beta-NAG excretion patterns were similar to changes detected in the SDS-PAGE system. No gross nephrotoxicity developed in these patients. Blood urea nitrogen, plasma creatinine, and plasma magnesium concentrations remained within normal limits. The pattern of protein excretion on SDS-PAGE was consistent with renal tubular rather than glomerular damage. The SDS-PAGE system provides an additional means of monitoring early subclinical nephrotoxicity of AG in CF patients.

Acetylglucosaminidase↗

Comparing the clinical evolution of cystic fibrosis screened neonatally to that of cystic fibrosis diagnosed from clinical symptoms: a 10-year retrospective study in a French region (Brittany).

Until the year 2000, systematic cystic fibrosis (CF) neonatal screening was only performed in a few regions of France. The Brittany region began in 1989, but not the neighboring region of Loire-Atlantique. The present study compares the clinical evolution of both affected populations 10 years after screening was started. Although the 77 screened and 36 nonscreened children were followed in different CF centers, they were included in similar care protocols. The clinical characteristics at diagnosis and their evolution over a 10-year period of all the children affected with CF and born between January 1, 1989 and December 31, 1998, excluding those with meconium ileus, were compared. There were no significant differences in sex ratio, gestational age, anthropometric data at birth, frequency of deltaF508 homozygotes, proportion of pancreatic-insufficient patients, and mean age between the two populations. Age at diagnosis was lower in the screened group (38 days vs. 472 days, P < 10(-7)), as was the delay in supplementation with pancreatic enzymes (1.7 months vs.15.9 months, P < 10(-7)). The proportion of children who were hospitalized at least once was higher among the nonscreened than the screened patients (86% vs. 49%, P < 10(-4)). Z-scores for weight and height were significantly better in the screened population, not only in the first years of life, but also at 5 years old for height and 8 years old for weight. The Shwachman and Brasfield scores were higher among the screened children during the whole period of follow-up. No significant differences in colonization by Pseudomonas aeruginosa nor in lung function were found. Given the homogeneity in the characteristics and the follow-up of both populations, the benefits in terms of nutrition and clinical well-being of neonatal screening appear to be clear, thus confirming the advantages of its general implementation.

Age of Onset↗

Challenges in care of adult CF patients--the specialist cystic fibrosis team.

Cystic fibrosis (CF) is the most common life-limiting, autosomal, recessive genetic disorder. The gene which is responsible for the symptoms of this disease is located on the long arm of chromosome 7 and encodes the protein called Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), an apical chloride channel in epithelial cells. CF is a "multi-system" disease. It affects many parts of the body and it has a varied clinical expression. All patients with CF should have access to specialist services and the treatment must be comprehensive and multidisciplinary. The multidisciplinary team approach is important when trying to optimize care given to the patient and their family. The cystic fibrosis team may include personnel from the following specialist areas: medical, nursing, physiotherapy, dietetics, psychological, social/supportive. Close coordination is vital. Ideally, 'all members of the team' should have had CF care-related training. The specialist team approach ensures that such specialized multidisciplinary expertise is applied in all aspects of care, better knowledge of individual families, continuity, knowledge of treatment advances and the ability to apply these in daily management. Doubtlessly CF team ensures families a specific point of contact and they know who to talk to. In 1997 The Department of Pulmonology Diseases in Poznań started running a programme for CF adults at our University--the second CF adult centre in Poland. Members of our CF team have experience in the management of adults who have cystic fibrosis. Its members include physicians, nurses, a physiotherpist, a dietitian, a social worker and a psychologist. We must to build the team approach in CF care and use effectively talents of multiprofessional team members as fully as possible to deliver better services to patients.

Adult↗