Nasal Potential Difference In Cystic Fibrosis Considering Severe Cftr Mutations.

The gold standard for diagnosing cystic fibrosis (CF) is a sweat chloride value above 60 mEq/L. However, this historical and important tool has limitations; other techniques should be studied, including the nasal potential difference (NPD) test. CFTR gene sequencing can identify CFTR mutations, but this method is time-consuming and too expensive to be used in all CF centers. The present study compared CF patients with two classes I-III CFTR mutations (10 patients) (G1), CF patients with classes IV-VI CFTR mutations (five patients) (G2), and 21 healthy subjects (G3). The CF patients and healthy subjects also underwent the NPD test. A statistical analysis was performed using the Mann-Whitney, Kruskal-Wallis, χ(2), and Fisher's exact tests, α = 0.05. No differences were observed between the CF patients and healthy controls for the PDMax, Δamiloride, and Δchloride + free + amiloride markers from the NPD test. For the finger value, a difference between G2 and G3 was described. The Wilschanski index values were different between G1 and G3. In conclusion, our data showed that NPD is useful for CF diagnosis when classes I-III CFTR mutations are screened. However, if classes IV-VI are considered, the NPD test showed an overlap in values with healthy subjects.

[factors Impacting The Growth And Nutritional Status Of Cystic Fibrosis Patients Younger Than 10 Years Of Age Who Did Not Undergo Neonatal Screening.]

The aim of this study was to evaluate by clinical and laboratory parameters how cystic fibrosis (CF) affects growth and nutritional status of children who were undergoing CF treatment but did not receive newborn screening. A historical cohort study of 52 CF patients younger than 10 years of age were followed in a reference center in Campinas, Southeast Brazil. Anthropometric measurements were abstracted from medical records until March/2010, when neonatal screening program was implemented. Between September/2009 and March/2010, parental height of the 52 CF patients were also measured. Regarding nutritional status, four patients had Z-scores ≤ -2 for height/age (H/A) and body mass index/age (BMI/A). The following variables were associated with improved H/A ratio: fewer hospitalizations, longer time from first appointment to diagnosis, longer time from birth to diagnosis and later onset of respiratory disease. Forced vital capacity [FVC(%)], forced expiratory flow between 25-75% of FVC [FEF25-75(%)], forced expiratory volume in the first second [FEV1(%)], gestational age, birth weight and early respiratory symptoms were associated with IMC/A. Greater number of hospitalizations, diagnosis delay and early onset of respiratory disease had a negative impact on growth. Lower spirometric values, lower gestational age, lower birth weight, and early onset of respiratory symptoms had negative impact on nutritional status. Malnutrition was observed in 7.7% of cases, but 23% of children had nutritional risk.

Shwachman-Kulczycki score still useful to monitor cystic fibrosis severity

INTRODUCTION: The Shwachman-Kulczycki score was the first scoring system used in cystic fibrosis to assess disease severity. Despite its subjectivity, it is still widely used. OBJECTIVE: To study correlations among forced expiratory volume in one second (FEV1), chest radiography, chest computed tomography, 6-minute walk test, and Shwachman-Kulczycki score in patients with cystic fibrosis and to test whether the Shwachman-Kulczycki score is still useful in monitoring the severity of the disease. METHODS: A cross-sectional prospective study was performed to analyze the correlations (Spearman). Patients with clinically stable cystic fibrosis, aged 3-21 years, were included. RESULTS: 43 patients, 19F/24M, mean age 10.5 + 4.7 years, with a median Shwachman-Kulczycki score of 70 were studied. The median Brasfield and Bhalla scores were 17 and 10, respectively. The mean Z score for the 6-minute walk test was -1.1 + 1.106 and the mean FEV1 was 59 + 26 (as percentage of predicted values). The following significant correlations versus the Shwachman-Kulczycki score were found: FEV1 (r = 0.76), 6-minute walk test (r = 0.71), chest radiography (r = 0.71) and chest computed tomography (r = -0.78). When patients were divided according to FEV1, a statistically significantly correlation with the Shwachman-Kulczycki score was found only in patients with FEV1 <70% (r = 0.67). CONCLUSIONS: The Shwachman-Kulczycki score remains an useful tool for monitoring the severity of cystic fibrosis, adequately reflecting the functional impairment and chest radiography and tomography changes, especially in patients with greater impairment of lung function. When assessing patients with mild lung disease its limitations should be considered and its usefulness in such patients should be evaluated in larger populations.

Rhinovirus C and Respiratory Exacerbations in Children with Cystic Fibrosis

To investigate a possible role for human rhinovirus C in respiratory exacerbations of children with cystic fibrosis, we conducted microbiologic testing on respiratory specimens from 103 such patients in Sao Paulo, Brazil, during 2006-2007. A significant association was found between the presence of human rhinovirus C and respiratory exacerbations.

Genomovar status, virulence markers and genotyping of Burkholderia cepacia complex strains isolated from Brazilian cystic fibrosis patients

Burkholderia cepacia complex isolates obtained by microbiological culture of respiratory samples from Brazilian CF patients were studied by recA based PCR, screened by specific PCR for virulence markers and genotyped by RAPD. Forty-one isolates of B. cepacia complex were identified by culture and confirmation of identity and genomovar determination obtained in 32 isolates, with predominance of B. cenocepacia (53.1%). Virulence markers were not consistently found among isolates. Genotyping did not identify identical patterns among different patients. B. cenocepacia was the most prevalent B. cepacia complex member among our patients, and cross-infection does not seem to occur among them. V 2008 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Isolation of Lautropia mirabilis from sputa of a cystic fibrosis patient

An aggregate-forming coccus, isolated twice as the predominant microorganism in sputa from a cystic fibrosis patient on consecutive days, was shown to belong to the species Lautropia mirabilis on the bases of similarities of 16S rRNA gene sequences and phenotype. These isolates of L. mirabilis appear to be the first reported from a patient with cystic fibrosis and outside of Denmark.

Evaluation of bioelectrical impedance for prospective nutritional assessment in cystic fibrosis

We have compared the use of bioelectrical impedance analysis (BIA) with anthropometry for the prediction of changes in total body potassium (TBK) in a group (n = 31) of children with cystic fibrosis. Linear regression analysis showed that TBK was highly correlated (r > 0.93) with height(2)/impedance, weight, height, and fat-free mass (FFM) estimated from skin-fold measurements. Changes in TBK were also correlated, but less well, with changes in height(2)/impedance, weight, height, and FFM (r = 0.69, 0.59, 0.44, and 0.40, respectively). The children were divided into two groups: those who had normal accretion of TBK (> 5%/y) and those who had suboptimal accretion of TBK (< 5%/y). Analysis of variance showed that the significant difference in the change in TBK between the groups was detectable by concomitant changes in impedance and weight but not by changes in height, FFM, or weight and height Z scores. The results of this study suggest that serial BIA measures may be useful as a predictor of progressive undernutrition and poor growth in children with cystic fibrosis. (C) Elsevier Science Inc. 1997.

Cystic fibrosis and CFTR

Cystic fibrosis (CF) is a complex disease affecting epithelial ion transport. There are not many diseases like CF that have triggered such intense research activities. The complexity of the disease is due to mutations in the CFTR protein, now known to be a Cl- channel and a regulator of other transport proteins. The various interactions and the large number of disease-causing CFTR mutations is the reason for a variable genotype-phenotype correlation and sometimes unpredictable clinical manifestation. Nevertheless, the research of the past 10 years has resulted in a tremendous increase in knowledge, not only in regard to CFTR but also in regard to molecular interactions and completely new means of ion channel and gene therapy.

Regulation and properties of KCNQ1 (K(v)LQT1) and impact of the cystic fibrosis transmembrane conductance regulator

The K+ channel KCNQ1 (K(V)LQT1) is a voltage-gated K+ channel, coexpressed with regulatory subunits such as KCNE1 (IsK, mink) or KCNE3, depending on the tissue examined. Here, we investigate regulation and properties of human and rat KCNQ1 and the impact of regulators such as KCNE1 and KCNE3. Because the cystic fibrosis transmembrane conductance regulator (CFTR) has also been suggested to regulate KCNQ1 channels we studied the effects of CFTR on KCNQ1 in Xenopus oocytes, Expression of both human and rat KCNQ1 induced time dependent K+ currents that were sensitive to Ba2+ and 293B. Coexpression with KCNE1 delayed voltage activation, while coexpression with KCNE3 accelerated current activation. KCNQ1 currents were activated by an increase in intracellular cAMP, independent of coexpression with KCNE1 or KCNE3. cAMP dependent activation was abolished in N-terminal truncated hKCNQ1 but was still detectable after deletion of a single PKA phosphorylation motif. In the presence but not in the absence of KCNE1 or KCNE3, K+ currents were activated by the Ca2+ ionophore ionomycin. Coexpression of CFTR with either human or rat KCNQ1 had no impact on regulation of KCNQ1 K+ currents by cAMP but slightly shifted the concentration response curve for 293B. Thus, KCNQ1 expressed in Xenopus oocytes is regulated by cAMP and Ca2+ but is not affected by CFTR.

Control of the cystic fibrosis transmembrane conductance regulator by alpha G(i) and RGS proteins

The cystic fibrosis transmembrane conductance regulator (CFTR) has been shown previously to be regulated by inhibitory G proteins. In the present study, we demonstrate inhibition of CFTR by alphaG(i2) and alphaG(i1), but not alphaG(0), in Xenopus oocytes. We further examined whether regulators of G protein signaling (RGS) proteins interfere with alphaG(i)-dependent inhibition of CFTR. Activation of CFTR by IBMX and forskolin was attenuated in the presence of alphaG(i2), indicating inhibition of CFTR by alphaG(i2) in Xenopus oocytes. Coexpression of the proteins RGS3 and RGS7 together with CFTR and alphaG(i2) partially recovered activation by IBMX/forskolin. 14-3-3, a protein that is known to interfere with RGS proteins, counteracted the effects of RGS3. These data demonstrate the regulation of CFTR by alphaG(i) in Xenopus oocytes. Because RGS proteins interfere with the G protein-dependent regulation of CFTR, this may offer new potential pathways for pharmacological intervention in cystic fibrosis. (C) 2001 Academic Press.

Pharmacotherapy of the ion transport defect in cystic fibrosis

1. More than 1300 different mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis (CF), a disease characterized by deficient epithelial Cl- secretion and enhanced Na+ absorption. The clinical course of the disease is determined by the progressive lung disease. Thus, novel approaches in pharmacotherapy are based primarily on correction of the ion transport defect in the airways. 2. The current therapeutic strategies try to counteract the deficiency in Cl- secretion and the enhanced Na+ absorption. A number of compounds have been identified, such as genistein and xanthine derivatives, which directly activate mutant CFTR. Other compounds may activate alternative Ca2+-activated Cl- channels or basolateral K+ channels, which supply the driving force for Cl- secretion. Apart from that, Na+ channel blockers, such as phenamil and benzamil, are being explored, which counteract the hyperabsorption of NaCl in CF airways. 3. Clinical trials are under way using purinergic compounds such as the P2Y(2) receptor agonist INS365. Activation of P2Y(2) receptors has been found to both activate Cl- secretion and inhibit Na+ absorption. 4. The ultimate goal is to recover Cl- channel activity of mutant CFTR by either enhancing synthesis and expression of the protein or by activating silent CFTR Cl- channels. Strategies combining these drugs with compounds facilitating Cl- secretion and inhibiting Na+ absorption in vivo may have the best chance to counteract the ion transport defect in cystic fibrosis.

The cystic fibrosis transmembrane conductance regulator (CFTR) inhibits ENaC through an increase in the intracellular Cl- concentration

Activation of the CFTR Cl- channel inhibits epithelial Na+ channels (ENaC), according to studies on epithelial cells and overexpressing recombinant cells. Here we demonstrate that ENaC is inhibited during stimulation of the cystic fibrosis trans-membrance conductance regulator (CFTR) in Xenopus oocytes, independent of the experimental set-up and the magnitude of the whole-cell current. Inhibition of ENaC is augmented at higher CFTR Cl- currents. Similar to CFTR, ClC-0 Cl- currents also inhibit ENaC, as well as high extracellular Na+ and Cl- in partially permeabilized oocytes. Thus, inhibition of ENaC is not specific to CFTR and seems to be mediated by Cl-.

Energy expenditure and the body cell mass in cystic fibrosis

Poor nutritional status in patients with cystic fibrosis (CF) is associated with severe lung disease, and possible causative factors include inadequate intake, malabsorption, and increased energy requirements. Body cell mass (which can be quantified by measurement of total body potassium) provides an ideal standard for measurements of energy expenditure. The aim of this study was to compare resting energy expenditure (REE) in patients with CF with both predicted values and age-matched healthy children and to determine whether REE was related to either nutritional status or pulmonary function. REE was measured by indirect calorimetry and body cell mass by scanning with total body potassium in 30 patients with CF(12 male, mean age = 13.07 +/- 0.55 y) and 18 healthy children (six male, mean age = 12.56 +/- 1.25 y). Nutritional status was expressed as a percentage of predicted total body potassium; Lung function was measured in the CF group by spirometry and expressed as the percentage of predicted forced expiratory volume in 1 s. Mean REE was significantly increased in the patients with CF compared with healthy children (119.3 +/- 3.1% predicted versus 103.6 +/- 5% predicted, P < 0.001) and, using multiple regression techniques, REE for total body potassium was significantly increased in patients with CF (P = 0.0001). There was no relation between REE and nutritional status or pulmonary disease status in the CF group. In conclusion, REE is increased in children and adolescents with CF but is not directly related to nutritional status or pulmonary disease. Nutrition 2001;17:22-25. (C)Elsevier Science Inc. 2001.