CFTR modulator therapy for cystic fibrosis caused by the rare c.3700A>G mutation.

BACKGROUND: The c.3700A>G mutation, a rare cystic fibrosis (CF)-causing CFTR mutation found mainly in the Middle East, produces full-length transcript encoding a missense mutation (I1234V-CFTR), and a cryptic splice site that deletes 6 amino acids in nucleotide binding domain 2 (I1234del-CFTR). METHODS: FRT cell models expressing I1234V-CFTR and I1234del-CFTR were generated. We also studied an I1234del-CFTR-expressing gene-edited human bronchial (16HBE14o-) cell model, and primary cultures of nasal epithelial cells from a c.3700A>G homozygous subject. To identify improved mutation-specific CFTR modulators, high-throughput screening was done using I1234del-CFTR-expressing FRT cells. Motivated by the in vitro findings, Trikafta was tested in two c.3700A>G homozygous CF subjects. RESULTS: FRT cells expressing full-length I1234V-CFTR had similar function to that of wildtype CFTR. I1234del-CFTR showed reduced activity, with modest activation seen with potentiators VX-770 and GLPG1837, correctors VX-809, VX-661 and VX-445, and low-temperature incubation. Screening identified novel arylsulfonyl-piperazine and spiropiperidine-quinazolinone correctors, which when used in combination with VX-445 increased current ~2-fold compared with the VX-661/VX-445 combination. The combination of VX-770 with arylsulfonamide-pyrrolopyridine, piperidine-pyridoindole or pyrazolo-quinoline potentiators gave 2-4-fold greater current than VX-770 alone. Combination potentiator (co-potentiator) efficacy was also seen in gene-edited I1234del-CFTR-expressing human bronchial epithelial cells. In two CF subjects homozygous for the c.3700A>G mutation, one subject had a 27 mmol/L decrease in sweat chloride and symptomatic improvement on Trikafta, and a second subject showed a small improvement in lung function. CONCLUSIONS: These results support the potential benefit of CFTR modulators, including co-potentiators, for CF caused by the c.3700A>G mutation.

Early acquisition and conversion of Pseudomonas aeruginosa in Hispanic youth with cystic fibrosis in the United States.

BACKGROUND: For unknown reasons, Hispanic patients with cystic fibrosis (CF) have more severe pulmonary disease than non-Hispanic white patients. In CF, the pulmonary pathogen Pseudomonas aeruginosa is associated with worse outcomes. We sought to determine if Hispanic patients with CF are at an increased risk of acquiring P. aeruginosa or acquire it earlier than non-Hispanic white patients. METHODS: This is a longitudinal study comparing the timing and risk of acquisition of different forms of P. aeruginosa between Hispanic and non-Hispanic white patients aged 0-21 years old with CF in the CF Foundation Patient Registry (CFFPR) in 2008-2013. The age at the initial acquisition of P. aeruginosa (initial acquisition, mucoid, chronic, multidrug-resistant) was summarized using Kaplan-Meier survival curves and analyzed using Cox proportional hazards regression models. RESULTS: Of 10,464 patients, 788 (7.5%) were Hispanic and 9,676 (92.5%) were non-Hispanic white. Hispanic patients acquired all forms of P. aeruginosa at a younger age than non-Hispanic white patients. Hispanic patients had a higher risk of acquiring P. aeruginosa than non-Hispanic white patients: the hazard ratio (HR) was 1.26 (95% CI 1.16-1.38, p<0.001) for initial P. aeruginosa, 1.59 (95% CI 1.43-1.77, p<0.001) for mucoid P. aeruginosa, 1.91 (95% CI 1.64-2.23, p<0.001) for multidrug-resistant P. aeruginosa, and 1.39 (95% CI 1.25-1.55, p<0.001) for chronic P. aeruginosa. CONCLUSIONS: Hispanic patients have an increased risk of acquiring P. aeruginosa and acquire it at an earlier age than non-Hispanic white patients in the United States. This may contribute to increased morbidity and mortality in Hispanic patients with CF.

Nanomolar-potency 'co-potentiator' therapy for cystic fibrosis caused by a defined subset of minimal function CFTR mutants.

Available CFTR modulators provide no therapeutic benefit for cystic fibrosis (CF) caused by many loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, including N1303K. We previously introduced the concept of 'co-potentiators' (combination-potentiators) to rescue CFTR function in some minimal function CFTR mutants. Herein, a screen of ~120,000 drug-like synthetic small molecules identified active co-potentiators of pyrazoloquinoline, piperidine-pyridoindole, tetrahydroquinoline and phenylazepine classes, with EC50 down to ~300 nM following initial structure-activity studies. Increased CFTR chloride conductance by up to 8-fold was observed when a co-potentiator (termed 'Class II potentiator') was used with a classical potentiator ('Class I potentiator') such as VX-770 or GLPG1837. To investigate the range of CFTR mutations benefitted by co-potentiators, 14 CF-associated CFTR mutations were studied in transfected cell models. Co-potentiator efficacy was found for CFTR missense, deletion and nonsense mutations in nucleotide binding domain-2 (NBD2), including W1282X, N1303K, c.3700A > G and Q1313X (with corrector for some mutations). In contrast, CFTR mutations G85E, R334W, R347P, V520F, R560T, A561E, M1101K and R1162X showed no co-potentiator activity, even with corrector. Co-potentiator efficacy was confirmed in primary human bronchial epithelial cell cultures generated from a N1303K homozygous CF subject. The Class II potentiators identified here may have clinical benefit for CF caused by mutations in the NBD2 domain of CFTR.

Regional variations in longitudinal pulmonary function: A comparison of Hispanic and non-Hispanic subjects with cystic fibrosis in the United States.

BACKGROUND: Hispanic subjects with cystic fibrosis (CF) have increased morbidity and mortality than non-Hispanic white subjects. The ethnic disparity in mortality varies by region. Factors influencing pulmonary function vary by both ethnicity and region. OBJECTIVE: To determine if the ethnic difference in pulmonary function varies by region. METHODS: This retrospective cohort study compared differences in longitudinal pulmonary function (percent-predicted forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1 ], forced expiratory flow at 25% to 75% [FEF25-75 ], FEV1 /FVC, and FEV1 decline) between Hispanic and non-Hispanic white subjects with CF by Census region of the United States (West, South, Midwest, and Northeast). Subjects were of ages 6 to 25 years and in the CF Foundation Patient Registry from 2008 to 2013. We used linear mixed effects models with subject-specific slopes and intercepts, adjusting for 14 demographic and clinical variables. RESULTS: Of 14 932 subjects, 1433 (9.6%) were Hispanic and 13 499 (90.4%) were non-Hispanic white. Hispanic subjects' FEV1 was 9.0% (8.3%-9.8%) lower than non-Hispanic white subjects in the West, while Hispanic subjects' FEV1 was only 4.0% (3.0%-5.0%) lower in the Midwest, 4.4% (3.1%-5.7%) lower in the Northeast, and 4.4% (3.2%-5.5%) lower in the South. Similarly, FVC and FEF25-75 were lower among Hispanic subjects compared to non-Hispanic white subjects in all US regions, with the biggest differences in the West. Only in the West was FEV1 /FVC significantly lower in Hispanic subjects (-0.019; -0.022 to -0.015). FEV1 decline was not significantly different between ethnicities in any region. CONCLUSIONS: In CF, Hispanic subjects have lower pulmonary function than non-Hispanic white subjects in all geographic regions with the largest difference in occurring in the West.

Combination potentiator ('co-potentiator') therapy for CF caused by CFTR mutants, including N1303K, that are poorly responsive to single potentiators.

BACKGROUND: Current modulator therapies for some cystic fibrosis-causing CFTR mutants, including N1303K, have limited efficacy. We provide evidence here to support combination potentiator (co-potentiator) therapy for mutant CFTRs that are poorly responsive to single potentiators. METHODS: Functional synergy screens done on N1303K and W1282X CFTR, in which small molecules were tested with VX-770, identified arylsulfonamide-pyrrolopyridine, phenoxy-benzimidazole and flavone co-potentiators. RESULTS: A previously identified arylsulfonamide-pyrrolopyridine co-potentiator (ASP-11) added with VX-770 increased N1303K-CFTR current 7-fold more than VX-770 alone. ASP-11 increased by ~65% of the current of G551D-CFTR compared to VX-770, was additive with VX-770 on F508del-CFTR, and activated wild-type CFTR in the absence of a cAMP agonist. ASP-11 efficacy with VX-770 was demonstrated in primary CF human airway cell cultures having N1303K, W1282X and G551D CFTR mutations. Structure-activity studies on 11 synthesized ASP-11 analogs produced compounds with EC50 down to 0.5 µM. CONCLUSIONS: These studies support combination potentiator therapy for CF caused by some CFTR mutations that are not effectively treated by single potentiators.

Pulmonary function disparities exist and persist in Hispanic patients with cystic fibrosis: A longitudinal analysis.

BACKGROUND: Hispanic patients with cystic fibrosis (CF) have decreased life expectancy compared to non-Hispanic white patients. Pulmonary function is a main predictor of life expectancy in CF. Ethnic differences in pulmonary function in CF have been understudied. The objective was to compare longitudinal pulmonary function between Hispanic and non-Hispanic white patients with CF. METHODS: This cohort study of 15 018 6-25 years old patients in the CF Foundation Patient Registry from 2008 to 2013 compared FEV1 percent predicted and longitudinal change in FEV1 percent predicted in Hispanic to non-Hispanic white patients. We used linear mixed effects models with patient-specific slopes and intercepts, adjusting for 14 demographic and clinical variables. We did sub-analyses by CFTR class, F508del copies, and PERT use. RESULTS: Hispanic patients had lower FEV1 percent predicted (79.9%) compared with non-Hispanic white patients (85.6%); (-5.8%, 95%CI -6.7% to -4.8%, P < 0.001), however, there was no difference in FEV1 decline over time. Patients on PERT had a larger difference between Hispanic and non-Hispanic white patients in FEV1 percent predicted than patients not on PERT (-6.0% vs -4.1%, P = 0.02). The ethnic difference in FEV1 percent predicted was not statistically significant between CFTR classes (Class I-III: -6.1%, Class IV-V: -5.9%, Unclassified: -5.7%, P > 0.05) or between F508del copies (None: -7.6%, Heterozygotes: -5.6%, Homozygotes: -5.3%, P > 0.05). CONCLUSIONS: Disparities in pulmonary function exist in Hispanic patients with CF early in life and then persist without improving or worsening over time. It is valuable to investigate the factors contributing to pulmonary function in Hispanic patients with CF.

In vivo and in vitro ivacaftor response in cystic fibrosis patients with residual CFTR function: N-of-1 studies.

RATIONALE: Ivacaftor, a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator, decreases sweat chloride concentration, and improves pulmonary function in 6% of cystic fibrosis (CF) patients with specific CFTR mutations. Ivacaftor increases chloride transport in many other CFTR mutations in non-human cells, if CFTR is in the epithelium. Some CF patients have CFTR in the epithelium with residual CFTR function. The effect of ivacaftor in these patients is unknown. METHODS: This was a series of randomized, crossover N-of-1 trials of ivacaftor and placebo in CF patients ≥8 years old with potential residual CFTR function (intermediate sweat chloride concentration, pancreatic sufficient, or mild bronchiectasis on chest CT). Human nasal epithelium (HNE) was obtained via nasal brushing and cultured. Sweat chloride concentration change was the in vivo outcome. Chloride current change in HNE cultures with ivacaftor was the in vitro outcome. RESULTS: Three subjects had decreased sweat chloride concentration (-14.8 to -40.8 mmol/L, P < 0.01). Two subjects had unchanged sweat chloride concentration. Two subjects had increased sweat chloride concentration (+23.8 and +27.3 mmol/L, P < 0.001); both were heterozygous for A455E and pancreatic sufficient. Only subjects with decreased sweat chloride concentration had increased chloride current in HNE cultures. CONCLUSIONS: Some CF patients with residual CFTR function have decreased sweat chloride concentration with ivacaftor. Increased chloride current in HNE cultures among subjects with decreased sweat chloride concentrations may predict clinical response to ivacaftor. Ivacaftor can increase sweat chloride concentration in certain mutations with unclear clinical effect. Pediatr Pulmonol. 2017;52:472-479. © 2017 Wiley Periodicals, Inc.

Correctors and Potentiators Rescue Function of the Truncated W1282X-Cystic Fibrosis Transmembrane Regulator (CFTR) Translation Product.

W1282X is the fifth most common cystic fibrosis transmembrane regulator (CFTR) mutation that causes cystic fibrosis. Here, we investigated the utility of a small molecule corrector/potentiator strategy, as used for ΔF508-CFTR, to produce functional rescue of the truncated translation product of the W1282X mutation, CFTR1281, without the need for read-through. In transfected cell systems, certain potentiators and correctors, including VX-809 and VX-770, increased CFTR1281 activity. To identify novel correctors and potentiators with potentially greater efficacy on CFTR1281, functional screens were done of ∼30,000 synthetic small molecules and drugs/nutraceuticals in CFTR1281-transfected cells. Corrector scaffolds of 1-arylpyrazole-4-arylsulfonyl-piperazine and spiro-piperidine-quinazolinone classes were identified with up to ∼5-fold greater efficacy than VX-809, some of which were selective for CFTR1281, whereas others also corrected ΔF508-CFTR. Several novel potentiator scaffolds were identified with efficacy comparable with VX-770; remarkably, a phenylsulfonamide-pyrrolopyridine acted synergistically with VX-770 to increase CFTR1281 function ∼8-fold over that of VX-770 alone, normalizing CFTR1281 channel activity to that of wild type CFTR. Corrector and potentiator combinations were tested in primary cultures and conditionally reprogrammed cells generated from nasal brushings from one W1282X homozygous subject. Although robust chloride conductance was seen with correctors and potentiators in homozygous ΔF508 cells, increased chloride conductance was not found in W1282X cells despite the presence of adequate transcript levels. Notwithstanding the negative data in W1282X cells from one human subject, we speculate that corrector and potentiator combinations may have therapeutic efficacy in cystic fibrosis caused by the W1282X mutation, although additional studies are needed on human cells from W1282X subjects.

Normalization of sweat chloride concentration and clinical improvement with ivacaftor in a patient with cystic fibrosis with mutation S549N.

The cystic fibrosis (CF) protein forms an anion channel in epithelial cells, and the absence or defective function of this channel results in the clinical manifestations of CF. CF is an autosomal recessive disorder, and its many disease-causing mutations divide into five or six classes. There are 10 known class 3 gating mutations, the most common of which is G551D. Ivacaftor is a drug that in vitro increases open time and transepithelial chloride transport in all 10 gating mutations, but it is approved for use only in patients with the G551D mutation. We report complete normalization of sweat chloride concentration and rapid clinical improvement over 6 weeks of treatment with ivacaftor in a patient with CF with the gating mutation S549N. The findings suggest that ivacaftor should be considered for use in patients with any of the known gating mutations.

Antibiotic prescribing during pediatric ambulatory care visits for asthma.

OBJECTIVE: National guidelines do not recommend antibiotics as an asthma therapy. We sought to examine the frequency of inappropriate antibiotic prescribing during US ambulatory care pediatric asthma visits as well as the patient, provider, and systemic variables associated with such practice. PATIENTS AND METHODS: Data from the National Ambulatory Medical Care Surveys and National Hospital Ambulatory Medical Care Survey were examined to assess office and emergency-department asthma visits made by children (aged < 18 years) for frequencies of antibiotic prescription. International Classification of Diseases, Ninth Revision (ICD-9) codes were used to assess the presence of coexisting conditions warranting antibiotics. Multivariable logistic regression models assessed associations with the prescription of antibiotics. RESULTS: From 1998 to 2007, an estimated 60.4 million visits occurred for asthma without another ICD-9 code justifying antibiotic prescription. Antibiotics were prescribed during 16% of these visits, most commonly macrolides (48.8%). In multivariate analysis, controlling for patient age, gender, race, insurance type, region, and controller medication use, systemic corticosteroid prescription (odds ratio [OR]: 2.69 [95% confidence interval (CI): 1.68-4.30]) and treatment during the winter (OR: 1.92 [95% CI: 1.05-3.52]) were associated with an increased likelihood of antibiotic prescription, whereas treatment in an emergency department was associated with decreased likelihood (OR: 0.48 [95% CI: 0.26-0.89]). A second multivariate analysis of only office-based visits demonstrated that asthma education during the visits was associated with reduced antibiotic prescriptions (OR: 0.46 [95% CI: 0.24-0.86]). CONCLUSIONS: Antibiotics are prescribed during nearly 1 in 6 US pediatric ambulatory care visits for asthma, ~ 1 million prescriptions annually, when antibiotic need is undocumented. Additional education and interventions are needed to prevent unnecessary antibiotic prescribing for asthma.

Airway surface liquid depth measured in ex vivo fragments of pig and human trachea: dependence on Na+ and Cl- channel function.

The airway surface liquid (ASL) is the thin fluid layer lining the airways whose depth may be reduced in cystic fibrosis. Prior measurements of ASL depth have been made in airway epithelial cell cultures. Here, we established methodology to measure ASL depth to approximately 1-microm accuracy in ex vivo fragments of freshly obtained human and pig tracheas. Airway fragments were mounted in chambers designed for perfusion of the basal surface and observation of the apical, fluorescently stained ASL by scanning confocal microscopy using a high numerical aperture lens immersed in perfluorocarbon. Measurement accuracy was verified using standards of specified fluid thickness. ASL depth in well-differentiated primary cultures of human nasal respiratory epithelium was 8.0 +/- 0.5 microm (SE 10 cultures) under basal conditions, 8.4 +/- 0.4 microm following ENaC inhibition by amiloride, and 14.5 +/- 1.2 microm following CFTR stimulation by cAMP agonists. ASL depth in human trachea was 7.0 +/- 0.7 microm under basal conditions, 11.0 +/- 1.7 microm following amiloride, 17.0 +/- 3.4 microm following cAMP agonists, and 7.1 +/- 0.5 microm after CFTR inhibition. Similar results were found in pig trachea. This study provides the first direct measurements of ASL depth in intact human airways and indicates the involvement of ENaC sodium channels and CFTR chloride channels in determining ASL depth. We suggest that CF lung disease may be caused by the inability of CFTR-deficient airways to increase their ASL depth transiently following secretory stimuli that in non-CF airways produce transient increases in ASL depth.

Glycosylation of sputum mucins is altered in cystic fibrosis patients.

Cystic fibrosis (CF) is characterized by chronic lung infection and inflammation, with periods of acute exacerbation causing severe and irreversible lung tissue damage. We used protein and glycosylation analysis of high-molecular mass proteins in saline-induced sputum from CF adults with and without an acute exacerbation, CF children with stable disease and preserved lung function, and healthy non-CF adult and child controls to identify potential biomarkers of lung condition. While the main high-molecular mass proteins in the sputum from all subjects were the mucins MUC5B and MUC5AC, these appeared degraded in CF adults with an exacerbation. The glycosylation of these mucins also showed reduced sulfation, increased sialylation, and reduced fucosylation in CF adults compared with controls. Despite improvements in pulmonary function after hospitalization, these differences remained. Two CF children showed glycoprotein profiles similar to those of CF adults with exacerbations and also presented with pulmonary flares shortly after sampling, while the remaining CF children had profiles indistinguishable from those of healthy non-CF controls. Sputum mucin glycosylation and degradation are therefore not inherently different in CF, and may also be useful predictive biomarkers of lung condition.

Hyperacidity of secreted fluid from submucosal glands in early cystic fibrosis.

Prior studies have shown that fluid secretions from airway submucosal glands in cystic fibrosis (CF) are reduced and hyperviscous, possibly contributing to the pathogenesis of CF airway disease. Because the CF transmembrane conductance regulator (CFTR) protein can transport both chloride and bicarbonate, we investigated whether gland fluid pH is abnormal in early CF, using nasal biopsies from pediatric subjects having minimal CF lung disease. Gland fluid pH, measured in freshly secreted droplets under oil stained with BCECF-dextran, was 6.57 +/- 0.09 (mean +/- SE) in biopsies from six CF subjects, significantly lower than 7.18 +/- 0.06 in eight non-CF biopsies (P < 0.01). To rule out the possibility that the apparent gland fluid hyperacidity in CF results from modification of fluid pH by the airway surface, a microcannulation method was used to measure pH in fluid exiting gland orifices. In pig trachea and human bronchi, gland fluid pH was reduced by up to 0.45 units by CFTR inhibitors, but was not affected by amiloride. Acid base transport in the surface epithelium of pig trachea was studied from pH changes in 300-nl fluid droplets deposited onto the oil-covered airway surface. The droplets had specified ionic composition/pH and/or contained transporter activators/inhibitors. We found evidence for CFTR-dependent bicarbonate transport by the tracheal surface epithelium as well as ATP/histamine-stimulated proton secretion, but not for sodium/proton or chloride/bicarbonate exchange. These results provide evidence for intrinsic hyperacidity in CF gland fluid secretions, which may contribute to CF airway pathology.

Proteomic analysis of sputum from adults and children with cystic fibrosis and from control subjects.

RATIONALE: Recurrent pulmonary exacerbations are associated with progressive lung disease in cystic fibrosis (CF). Current definitions of an exacerbation, although not precisely defined, include new/worsening symptoms, declining lung function, and/or changing radiologic appearance. Early diagnosis of exacerbations by rapid noninvasive means should expedite therapeutic intervention, thereby minimizing lung damage. OBJECTIVES: To identify biomarkers of lung exacerbation for point-of-care monitoring of CF lung disease progression. METHODS: Saline-induced sputum was collected from adults with CF with an exacerbation and requiring hospitalization (FEV(1) < 60%), a subset of these adults at hospital discharge, children with stable CF and preserved lung function (FEV(1) > 70%), and control subjects (FEV(1) > 80%). Sputum was arrayed by two-dimensional electrophoresis and differentially expressed proteins were identified by proteomic analysis. MEASUREMENTS AND MAIN RESULTS: Sputum profiles from adults with CF with an exacerbation were characterized by extensive proteolytic degradation and influx of inflammation-related proteins, with some adults with CF approaching a "healthy" protein profile after hospitalization. Two children with CF showed profiles and biomarker expression resembling those of adults with an exacerbation. Levels of differentially expressed myeloperoxidase, cleaved alpha(1)-antitrypsin, IgG degradation, interleukin-8, and total protein concentration, together with their correlation to FEV(1), were statistically significant. Statistical correlation analyses indicated that changes in myeloperoxidase expression and IgG degradation were the strongest predictors of FEV(1). CONCLUSIONS: We identified extensive protein degradation and differentially expressed proteins as biomarkers of inflammation relating to pulmonary exacerbations. Prediction of exacerbation onset and more precise evaluation of the extent of resolution with treatment could be achieved by including biomarkers in standard assessment.

Submucosal gland dysfunction as a primary defect in cystic fibrosis.

It has been proposed that defective submucosal gland function in CF airways is a major determinant of CF airway disease. We tested the hypothesis that submucosal gland function is defective early in CF subjects with minimal clinical disease. Functional assays of gland fluid secretion rate and viscosity were performed on freshly obtained nasal biopsies from 6 CF subjects and 5 non-CF controls (age range 2-22 years). Secretions from individual submucosal glands were visualized by light/fluorescence microscopy after orienting and immobilizing biopsy specimens in a custom chamber. The viscosity of freshly secreted gland fluid after pilocarpine, measured by fluorescence recovery after photobleaching of microinjected FITC-dextran, was 4.9 +/- 0.2- vs. 2.2 +/- 0.2-fold greater than water viscosity in CF vs. non-CF specimens, respectively (SE, P<10(-4)). Gland fluid secretion rate in CF specimens, measured by video imaging (4.5+/-0.5 nL/min/gland, n=6), was 2.7-fold reduced compared to non-CF specimens (n=3, P<0.05). Quantitative histology revealed similar size and morphology of submucosal glands in CF and non-CF specimens. Our results suggest that defective airway submucosal gland function is an early, primary defect in CF. Therapies directed at normalizing gland fluid secretion early in CF may thus reduce lung disease.

CFTR involvement in nasal potential differences in mice and pigs studied using a thiazolidinone CFTR inhibitor.

Nasal potential difference (PD) measurements have been used to demonstrate defective CFTR function in cystic fibrosis (CF) and to evaluate potential CF therapies. We used the selective thiazolidinone CFTR inhibitor CFTR(inh)-172 to define the involvement of CFTR in nasal PD changes in mice and pigs. In normal mice infused intranasally with a physiological saline solution containing amiloride, nasal PD was -4.7 +/- 0.7 mV, hyperpolarizing by 15 +/- 1 mV after a low-Cl- solution, and a further 3.9 +/- 0.5 mV after forskolin. CFTR(inh)-172 produced 1.1 +/- 0.9- and 4.3 +/- 0.7-mV depolarizations when added after low Cl- and forskolin, respectively. Systemically administered CFTR(inh)-172 reduced the forskolin-induced hyperpolarization from 4.7 +/- 0.4 to 0.9 +/- 0.1 mV but did not reduce the low Cl(-)-induced hyperpolarization. Nasal PD was -12 +/- 1 mV in CF mice after amiloride, changing by <0.5 mV after low Cl- or forskolin. In pigs, nasal PD was -14 +/- 3 mV after amiloride, hyperpolarizing by 13 +/- 2 mV after low Cl- and a further 9 +/- 1 mV after forskolin. CFTR(inh)-172 and glibenclamide did not affect nasal PD in pigs. Our results suggest that cAMP-dependent nasal PDs in mice primarily involve CFTR-mediated Cl- conductance, whereas cAMP-independent PDs are produced by a different, but CFTR-dependent, Cl- channel. In pigs, CFTR may not be responsible for Cl- channel-dependent nasal PDs. These results have important implications for interpreting nasal PDs in terms of CFTR function in animal models of CFTR activation and inhibition.

Health values of adolescents with cystic fibrosis.

OBJECTIVES: To assess health values (utilities) in adolescents with cystic fibrosis (CF) and to evaluate how health status and clinical factors affect their health values. METHODS: Adolescents 12 to 18 years of age completed the Child Health Questionnaire (CHQ), Health Utilities Index Mark 2 (HUI2), and 3 health value measures: the visual analog scale (VAS), time tradeoff (TTO), and standard gamble (SG). Severity of illness was measured by percent of predicted forced expiratory volume in 1 second (FEV(1)) and frequency of pulmonary exacerbations. RESULTS: The mean age (+/- SD) of the 65 adolescents was 15.1 (+/- 2.1) years; 53.8% were male; their mean FEV(1) was 72.8% (+/- 27.0%) predicted. The mean TTO utility was 0.96 (+/- 0.07) and the mean SG utility was 0.92 (+/- 0.15). In multivariable analysis, the General Health Perceptions domain from the CHQ was the only health status scale significantly associated with the VAS, TTO, and SG. No clinical or demographic measures were significantly related to both TTO and SG scores. CONCLUSIONS: Direct utility assessment in adolescents with CF is feasible. Their TTO and SG utilities are generally high, indicating that they are willing to trade very little of their life expectancy or take more than a small risk of death to obtain perfect health. Their self-rated health perceptions are related to their health values, but, as in adult populations, only moderately so, indicating that health values are highly individualistic. Therefore, health values should be ascertained directly from adolescents.

Idiopathic congenital central hypoventilation syndrome: the next generation.

Idiopathic congenital central hypoventilation syndrome (CCHS) is a rare disorder in which affected children have a decreased sensitivity of their respiratory centers to hypercarbia and hypoxia, as well as evidence for generalized autonomic nervous system dysfunction. A genetic origin has long been hypothesized for CCHS. Previous reports of the syndrome among twins, siblings, and half siblings, as well as an established association with Hirschsprung disease and neural crest tumors support this genetic hypothesis. Here, we present the first reported offspring born to four women diagnosed with idiopathic CCHS. Their children display a spectrum of abnormalities with one child being diagnosed with CCHS, one child with recurrent apparent life threatening events, one infant born prematurely with severe chronic lung disease and diminished ventilatory responses to carbon dioxide, and one infant who is apparently healthy with no clinical manifestations suggestive of disordered respiratory control to date. Two and potentially three of these patients illustrate transmission of altered respiratory control by CCHS patients into the next generation, furthering the evidence that CCHS is part of a broadly based inherited syndrome of autonomic nervous system dysfunction.