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[Results of the sweat test, carried out by 2 methods, for the diagnosis of cystic fibrosis].

Un review the results of the sweat test for the diagnosis of cystic fibrosis performed by 2 methods: Electric conductivity of the sweat (2,517 test in non-cystic fibrosis and 114 in 37 cystic fibrosis children) and skin chloride electrode (121 test in non-cystic fibrosis and 20 in cystic fibrosis children). A 1% rate of false positive results was obtained with the former along with 6,1% falsely negative results in cystic fibrosis patients. The skin chloride electrode method was much less specific and sensitive. The diagnosis of cystic fibrosis should only be made once repeatedly altered sweat chloride concentrations are obtained together with careful correlation with the clinical findings. We think that both the implications of the diagnosis and the thoroughness needed in the proper performance of the sweat test warrant that the diagnosis should always be confirmed in a centre with experience in the disease.

Adolescent↗

Mild cystic fibrosis linked to chromosome 7q22 markers with an uncommon haplotype.

Cystic fibrosis is the commonest autosomal recessive genetic disorder among northern Europeans and their descendants. Recently, investigators have mapped the gene for cystic fibrosis to chromosome 7. We report the results of DNA linkage analysis in a consanguineous family with mild cystic fibrosis. The probes used in this study were pmet D. pmet H, XV-2c, KM.19, and pJ3.11. Linkage to the identified cystic fibrosis locus of 7q22 was established with a peak logarithm of the odds (lod) score of 3.00 at a recombination fraction theta =0.00 using the tightly linked marker KM.19. In addition, we found the D haplotype, which is not commonly associated with cystic fibrosis, to be segregating in this family. The D haplotype is composed of the 1.4-kb allele detectable by XV-2c and the 6.6-kb allele detectable by KM.19. The three patients with cystic fibrosis who had consanguineous parents were homozygous DD, were among the least severely affected, and had no pancreatic insufficiency. The five patients with unrelated parents were heterozygous for the D haplotype and the commoner B haplotype, except one patient who was homozygous DD. All affected persons with pancreatic insufficiency had the DB genotype. These DNA linkage studies provide additional evidence for the existence of a cystic fibrosis allele that is associated with mild disease.

Adult↗

Ear disease in children with cystic fibrosis.

OBJECTIVE: To assess otitis media in children with cystic fibrosis. DESIGN: Prospective prevalence survey. SETTING: Otolaryngology and cystic fibrosis/pulmonology outpatient clinics, Children's Hospital of Pittsburgh (Pa), a regional referral center. PATIENTS: Seventy patients, aged 4 months to 17 years, with documented cystic fibrosis who presented to the cystic fibrosis/pulmonary clinic with scheduled appointments were asked to volunteer for the study. The 70 patients recruited represent approximately one fourth of the children younger than 17 years with cystic fibrosis who were followed up by the cystic fibrosis/pulmonary clinic. INTERVENTION: Ear, nose, and throat examination including pneumatic otoscopy, with tympanometry when indicated; relevant history taking. MAIN OUTCOME MEASURE: Presence or absence of otitis media. RESULTS: Seven (10%) of the 70 patients had unilateral or bilateral otitis media. CONCLUSIONS: Children with cystic fibrosis have a low prevalence of otitis media compared with normal children.

Acute Disease↗

Down-regulation of the anti-inflammatory protein annexin A1 in cystic fibrosis knock-out mice and patients.

Cystic fibrosis is a fatal human genetic disease caused by mutations in the CFTR gene encoding a cAMP-activated chloride channel. It is characterized by abnormal fluid transport across secretory epithelia and chronic inflammation in lung, pancreas, and intestine. Because cystic fibrosis (CF) pathophysiology cannot be explained solely by dysfunction of cystic fibrosis transmembrane conductance regulator (CFTR), we applied a proteomic approach (bidimensional electrophoresis and mass spectrometry) to search for differentially expressed proteins between mice lacking cftr (cftr(tm1Unc), cftr-/-) and controls using colonic crypts from young animals, i.e. prior to the development of intestinal inflammation. By analyzing total proteins separated in the range of pH 6-11, we detected 24 differentially expressed proteins (>2-fold). In this work, we focused on one of these proteins that was absent in two-dimensional gels from cftr-/- mice. This protein spot (molecular mass, 37 kDa; pI 7) was identified by mass spectrometry as annexin A1, an anti-inflammatory protein. Interestingly, annexin A1 was also undetectable in lungs and pancreas of cftr-/- mice, tissues known to express CFTR. Absence of this inhibitory mediator of the host inflammatory response was associated with colonic up-regulation of the proinflammatory cytosolic phospholipase A2. More importantly, annexin A1 was down-regulated in nasal epithelial cells from CF patients bearing homozygous nonsense mutations in the CFTR gene (Y122X, 489delC) and differentially expressed in F508del patients. These results suggest that annexin A1 may be a key protein involved in CF pathogenesis especially in relation to the not well defined field of inflammation in CF. We suggest that decreased expression of annexin A1 contributes to the worsening of the CF phenotype.

Adolescent↗

Skin reactivity to atypical mycobacteria in cystic fibrosis.

Atypical mycobacterial disease has been described in a small number of patients with cystic fibrosis. Apart from one uncontrolled study, there is little information regarding atypical mycobacterial skin reactivity in this group of patients. We evaluated delayed cutaneous hypersensitivity to purified extracts of Mycobacterium avium, Mycobacterium intracellular, Mycobacterium kansasii and Mycobacterium bovis in 23 healthy controls and 43 adult and adolescent patients with cystic fibrosis. Fifteen of the cystic fibrosis group were receiving regular corticosteroids. Additionally, direct smear examination and Lowenstein Jensen culture were performed on sputum from the cystic fibrosis group. The prevalence of positive skin reactions was similar in the group with cystic fibrosis (30%) and in the control group (57%). Subgroup analysis showed that those cystic fibrosis patients receiving corticosteroids had a markedly lower prevalence of positive reactions (7%) compared to controls (P less than 0.01). When this subgroup was excluded from analysis, the prevalence of positive skin reactions among patients with cystic fibrosis was 43%. In the prospective sputum bacteriology study, one of the 43 cases grew Mycobacterium avium-intracellulare and had clinical and radiological evidence of this disease. Of note, this patient showed positive skin tests to all four mycobacterial species tested. Our data show no difference in the prevalence rate of positive skin reactions to atypical mycobacterial antigens between a control population and an adult cystic fibrosis population. In addition, the predictive value of skin testing is low in cystic fibrosis due to the high prevalence of cross-reactivity between different mycobacterial species and the high prevalence of anergy among those patients with advanced disease receiving treatment with corticosteroids.

Adolescent↗

Genetic modifiers of lung disease in cystic fibrosis.

BACKGROUND: Polymorphisms in genes other than the cystic fibrosis transmembrane conductance regulator (CFTR) gene may modify the severity of pulmonary disease in patients with cystic fibrosis. METHODS: We performed two studies with different patient samples. We first tested 808 patients who were homozygous for the DeltaF508 mutation and were classified as having either severe or mild lung disease, as defined by the lowest or highest quartile of forced expiratory volume in one second (FEV1), respectively, for age. We genotyped 16 polymorphisms in 10 genes reported by others as modifiers of disease severity in cystic fibrosis and tested for an association in patients with severe disease (263 patients) or mild disease (545). In the replication (second) study, we tested 498 patients, with various CFTR genotypes and a range of FEV1 values, for an association of the TGFbeta1 codon 10 CC genotype with low FEV1. RESULTS: In the initial study, significant allelic and genotypic associations with phenotype were seen only for TGFbeta1 (the gene encoding transforming growth factor beta1), particularly the -509 and codon 10 polymorphisms (with P values obtained with the use of Fisher's exact test and logistic regression ranging from 0.006 to 0.0002). The odds ratio was about 2.2 for the highest-risk TGFbeta1 genotype (codon 10 CC) in association with the phenotype for severe lung disease. The replication study confirmed the association of the TGFbeta1 codon 10 CC genotype with more severe lung disease in comparisons with the use of dichotomized FEV1 for severity status (P=0.0002) and FEV1 values directly (P=0.02). CONCLUSIONS: Genetic variation in the 5' end of TGFbeta1 or a nearby upstream region modifies disease severity in cystic fibrosis.

Adolescent↗

Dystrophic axons and spinal cord demyelination in cystic fibrosis.

Neuropathologic changes in patients with cystic fibrosis include dystrophic axons in the nucleus gracilis and demyelination of the fasciculus gracilis. We reviewed 43 autopsy cases of cystic fibrosis to determine the incidence and severity of these changes. Sixty-six percent of patients developed dystrophic axons. There was a direct correlation between severity of neuroaxonal dystrophy and duration of disease. Demyelination of the fasciculus gracilis occurred in 11%. The neuropathology of cystic fibrosis resembles that of vitamin E deficiency in animals. However, vitamin E replacement failed to prevent neuropathologic changes in these patients.

Adolescent↗

Pharmacological treatment of the biochemical defect in cystic fibrosis airways.

The understanding of the biochemical defect in cystic fibrosis (CF) has advanced considerably since discovery of the CF gene in 1989 and characterization of its product. Studies showing that the abnormality in chloride flux could be corrected by transfection of wild-type cystic fibrosis transmembrane conductance regulator (CFTR) complimentary deoxyribonucleic acid (cDNA) have led to gene therapy trials on both sides of the Atlantic. However, gene therapy as a treatment for CF has yet to be realized. Pharmacological manipulation of the biochemical defect may provide an alternative or complementary approach to treatment. This review will discuss pharmacological agents in development which could correct the abnormal ion movement. The mechanisms of action of these pharmacological agents can be divided broadly into drugs which affect the most common CF mutation, deltaF508, which increase trafficking of the mutant CF protein to the apical membrane; drugs which increase chloride secretion; and drugs which reduce sodium reabsorption across the apical membrane. Treatment options for cystic fibrosis have developed rapidly since discovery of the cystic fibrosis gene over a decade ago. The targeting of specific therapies for particular cystic fibrosis genotypes and the use of combination treatments of chloride channel openers with sodium channel blockers are likely to be key advances in the next decade.

Animals↗

Altered responsiveness to photic stimuli contribute to circadian disruption in cystic fibrosis.

BACKGROUND: People with cystic fibrosis (pwCF) and animal models show evidence of disrupted circadian rhythms (CR). CRs are controlled by light sensitive neurons of the suprachiasmatic nucleus (SCN). Characterizing how the CF SCN responds to light will inform mechanisms behind CR disruption and help to inform CR based treatments to mitigate CF symptoms exacerbated by circadian disruption. METHODS: Mice were entrained and subsequently exposed to a 30 min light pulse one hour after usual lights out. The magnitude of the resulting phase delay in subsequent activity onset and molecular correlates of photic input at the SCN were then compared between CF and WT mice. RESULTS: Light induced phase delays of activity onset in CF mice were reduced compared to WT controls. Reduced behavioral responses were also associated with altered molecular responses in the SCN, including attenuated cFOS levels in CF vs WT SCN. Data show that phosphorylation of ribosomal protein 6 (pS6) is reduced in CF, while targets down stream of 4E-BP1 such as vasoactive intestinal polypeptide levels (VIP) appear the same between genotypes. CONCLUSIONS: Behavioral and molecular responses to a light pulse differ between CF and WT mice. Together these data suggest that similar photic input from the retina is being received by the SCN of CF and WT mice, but the mounted intracellular response to that photic input differs in CF. Investigation into these differences will be integral to understanding circadian disruption in CF and informing future intervention for CF symptoms known to be exacerbated by circadian disruption.

Animals↗

Sexual adaptation among single young adults with cystic fibrosis.

The sexual adaptation of 48 single young adults with cystic fibrosis and a comparably aged single group without chronic disease was assessed using interviews and questionnaires. The patients were also compared to a previously studied group of married patients with cystic fibrosis. Single female patients with cystic fibrosis began dating later, dated less often, felt less attractive, had less sexual desire, and had more sexual problems than did physically healthy female subjects. Single male patients with cystic fibrosis seemed to fare far better than their female counterparts and approximated the healthy male group in all parameters studied. For both the single and married groups with cystic fibrosis, no significant relationship between the severity of disease and sexual health was evident. The single patients were diagnosed at a significantly earlier age and their general health scores were poorer than the married patients. The vulnerability of female patients with cystic fibrosis to psychosexual disruption suggests that attention be focused on the differential effects of other chronic illnesses upon male and female adult sexual adaptation.

Adult↗

Evaluation of the efficacy and safety of in vitro, adenovirus-mediated transfer of the human cystic fibrosis transmembrane conductance regulator cDNA.

Cystic fibrosis (CF) is a common, fatal recessive disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene manifested by abnormalities in the regulation of chloride ion (Cl-) secretion across the apical membrane of epithelial cells throughout the body. Adenovirus-mediated delivery of the normal CFTR cDNA and correction of the CF epithelial cell Cl- secretory phenotype suggests the feasibility of gene therapy for CF lung disease. Few studies, however, have focused on the evaluation of the safety of the adenovirus-mediated gene transfer approach. This study presents in vitro data on the efficacy and safety of adenovirus-mediated transfer of the human CFTR cDNA using Av1Cf2. Av1Cf2-mediated transfer of the human CFTR cDNA complemented the abnormal cAMP-regulated Cl- permeability of cells with the CF epithelial phenotype. Av1 vectors did not replicate infectious virus in HeLa cells infected in vitro, although trace vector DNA synthesis was observed at very high multiplicity of infection. Expression of the adenoviral late gene for the hexon capsid protein was observed at trace levels in Av1 vector-infected HeLa cells, but not in freshly isolated human bronchial epithelial cells, consistent with the pattern of DNA synthesis observed in these different target cells. Although, these observations support the efficacy and safety of use of Av1Cf2 for treatment of the fatal pulmonary component of CF.

Adenoviruses, Human↗

Cystic fibrosis with normal sweat chloride concentration--case report.

Cystic fibrosis is a genetic disease usually diagnosed by abnormal sweat testing. We report a case of an 18-year-old female with bronchiectasis, chronic P. aeruginosa infection, and normal sweat chloride concentrations who experienced rapid decrease of lung function and clinical deterioration despite treatment. Given the high suspicion of cystic fibrosis, broad genotyping testing was performed, showing a compound heterozygous with deltaF508 and 3849+10 kb C-->T mutations, therefore confirming cystic fibrosis diagnosis. Although the sweat chloride test remains the gold standard for the diagnosis of cystic fibrosis, alternative diagnostic tests such as genotyping and electrophysiologic measurements must be performed if there is suspicion of cystic fibrosis, despite normal or borderline sweat chloride levels.

Adolescent↗

Multiplex genotyping for cystic fibrosis from filter paper blood spots.

Cystic fibrosis is a common disease of the Caucasian population and is associated with significant early mortality. We present a simple and rapid method for cystic fibrosis genotyping from filter paper blood spots, using a currently available commercial genotyping kit. Using multiplex technology, genotype information on the four most common UK mutations can easily be obtained within a single working day. Used in conjunction with current immunoreactive typsinogen screening protocols, blood spot genotyping offers a method of hastening the diagnosis, and thus treatment, of cystic fibrosis.

Child↗

Cystic fibrosis as a cause of infertility.

Cystic fibrosis (CF) is one of the autosomal recessive diseases, caused by mutations in a gene known as cystic fibrosis transmembrane regulator (CFTR). The majority of adult males with CF (99%) is characterized by congenital bilateral absence of vas deferens (CBAVD). CBAVD is encountered in 1-2% of infertile males without CF. Females with CF are found to be less fertile than normal healthy women. In females with CF, delayed puberty and amenorrhoea are common due to malnutrition. CFTR mutations are also associated with congenital absence of the uterus and vagina (CAUV). The National Institutes of Health recommend genetic counseling for any couple seeking assisted reproductive techniques with a CF male or obstructive azoospermia which is positive for a CF mutation.

Cystic Fibrosis↗

Characterization of an intron 12 splice donor mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

Cystic fibrosis, the most common lethal genetic disease in the white population, is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Analysis of DNA from a pancreatic insufficient patient by chemical mismatch cleavage and subsequent DNA sequencing led to the identification of a potential splice mutation in the CFTR gene. A transition of the invariant guanosine to adenosine (1898 + 1G > A) was found at the splice donor site of intron 12. To determine the effect of this mutation on the patient's CFTR transcripts, RNA from the nasal epithelium was reverse transcribed and amplified by the polymerase chain reaction (RT-PCR). Direct sequencing of the PCR products revealed that the transcript from the chromosome with the 1898 + 1G > A mutation had skipped exon 12 entirely, resulting in a joining of exons 11 and 13. Deletion of exon 12 results in the removal of a highly conserved region which encodes the Walker B consensus sequence of the first nucleotide-binding fold of CFTR.

Adult↗

Physicochemical characterization and biological activity of intrinsic factor in cystic fibrosis.

Absorption of crystalline labeled cobalamin is strongly decreased in cases of cystic fibrosis. In order to determine if this is due to an alteration or a lack of activation of intrinsic factor by proteases, the physicochemical properties and biological activity of intrinsic factor have been studied. Intrinsic factor was purified 800-fold from stimulated gastric juice of cystic fibrosis patients with a yield of 64.2%. Cystic fibrosis intrinsic factor had an estimated Mr of 57,000 in SDS-polyacrylamide gel electrophoresis. Its carbohydrate content resembled that of normal human intrinsic factor, except that the ratio fucose/sialic acid was higher (6.1 and 1.6, respectively) and that the content in N-acetylgalactosamine was decreased. The same alterations in carbohydrate composition were observed for Hc purified from cystic fibrosis saliva. Purified intrinsic factor from cystic fibrosis gastric juice was biologically active in vitro in the presence of ileal solubilized receptor as well as in vivo (Schilling test). The fate of iodinated cystic fibrosis intrinsic factor in guinea pig ileum studied by high-resolution radioautography was similar to that of normal intrinsic factor. In conclusion, despite modifications of the carbohydrate content of the molecule, the biological activity of intrinsic factor is not altered in cases of cystic fibrosis. The malassimilation of crystalline cobalamin observed in cystic fibrosis is due to a mechanism independent from intrinsic factor secretion.

Animals↗

Controlled study of Pseudomonas cepacia and Pseudomonas maltophilia in cystic fibrosis.

In a retrospective study, children with cystic fibrosis who were colonised with Pseudomonas cepacia were compared with a control group who were colonised with Pseudomonas maltophilia. Out of 216 children with cystic fibrosis seen between 1983 and 1990, P cepacia was recovered from 13 (median age at colonisation 12.2 years) and P maltophilia from 23 (median age at first colonisation 6.1 years), and both organisms were recovered in five cases. With the exception of two patients with P cepacia in whom no other pathogens were found, all the patients with P cepacia or P maltophilia had co-colonisation with Pseudomonas aeruginosa. The lack of spread of P cepacia to siblings with cystic fibrosis, and the relative lack of inpatient contact between colonised and uncolonised patients suggest that cross infection is not the sole route whereby patients with cystic fibrosis become infected, but the possibility of cross infection cannot be excluded from our data. Three patients with P cepacia died, but two of these had shown appreciable respiratory deterioration before colonisation with P cepacia; there was no evidence of unexpected deterioration in the remainder or in the controls with P maltophilia. By 1990, the prevalence of P cepacia was 9/133 (7%) and that of P maltophilia was 13/133 (10%), but it was impossible to determine to what extent this increase was due to the introduction of the routine use of selective media. Further studies are required to establish whether patients with and without P cepacia should be segregated.

Adolescent↗

Processing of mutant cystic fibrosis transmembrane conductance regulator is temperature-sensitive.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a plasma membrane Cl- channel regulated by cyclic AMP-dependent phosphorylation and by intracellular ATP. Mutations in CFTR cause cystic fibrosis partly through loss of cAMP-regulated Cl- permeability from the plasma membrane of affected epithelia. The most common mutation in cystic fibrosis is deletion of phenylalanine at residue 508 (CFTR delta F508) (ref. 10). Studies on the biosynthesis and localization of CFTR delta F508 indicate that the mutant protein is not processed correctly and, as a result, is not delivered to the plasma membrane. These conclusions are consistent with earlier functional studies which failed to detect cAMP-stimulated Cl- channels in cells expressing CFTR delta F508 (refs 16, 17). Chloride channel activity was detected, however, when CFTR delta F508 was expressed in Xenopus oocytes, Vero cells and Sf9 insect cells. Because oocytes and Sf9 cells are typically maintained at lower temperatures than mammalian cells, and because processing of nascent proteins can be sensitive to temperature, we tested the effect of temperature on the processing of CFTR delta F508. Here we show that the processing of CFTR delta F508 reverts towards that of wild-type as the incubation temperature is reduced. When the processing defect is corrected, cAMP-regulated Cl- channels appear in the plasma membrane. These results reconcile previous contradictory observations and suggest that the mutant most commonly associated with cystic fibrosis is temperature-sensitive.

3T3 Cells↗