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Laboratory parameter profiles among patients with cystic fibrosis.

BACKGROUND: Clinical trials in cystic fibrosis (CF) currently use laboratory-specific reference ranges to evaluate chemistry and hematology measurements. Laboratory-specific normal reference ranges may not accurately reflect what is abnormal but clinically insignificant among CF patients. METHODS: To address this concern, data from the Phase III trial of inhaled tobramycin in CF patients was used to describe the distribution and variability of laboratory parameters. The laboratory specimens were analyzed at a central laboratory after being obtained at baseline and throughout the 24-week trial. RESULTS: At the time of entry into the clinical trial, 91% (463 of 508) of patients had at least a single value outside the normal range. Liver function tests (AST, ALT) were above the normal range in 16% and 12% of the patients respectively, with 2.4% of patients having an AST>2.0 times the upper limit of normal. Of the 243 patients on placebo, 242 (99.6%) had at least one laboratory parameter that changed from normal to abnormal during the 24-week follow-up period. Of those same placebo patients, 11.5% (N=28) had a laboratory parameter change from a Common Toxicity Criteria (CTC) grade 0 to grade 2 or higher during follow-up. CONCLUSIONS: Patients with CF frequently have laboratory values outside the normal range and have significant longitudinal variability of laboratory values. Interpretation of adverse events in the clinical trial setting may be complicated by the underlying high rates of some laboratory abnormalities in the CF population. This data was presented in poster format at the American Thoracic Society International Conference, Atlanta, USA, 2002, appearing subsequently in the Conference proceedings [Goss CH, Mayer-Hamblett N, Yunker A, Waltz DA, Kronmal RA, Ramsey BW. Laboratory parameter profiles among patients with cystic fibrosis. Am J Rep Crit Care Med 2002;165(8):A283].

Adolescent↗

Premature senescence in cultured skin fibroblasts from subjects with cystic fibrosis.

Cultured skin fibroblasts from subjects with cystic fibrosis exhibited normal population doubling times in early passages. After about 13 cumulative population doublings, cystic fibrosis lines doubled more slowly than controls and ceased doubling after about 19 weekly passages. Control lines continued doubling for 27 passages. The premature senescence noted in cells from subjects with cystic fibrosis reconciles controversial observations of cell doubling reported in the literature. Data presented here demonstrate that experiments with cystic fibrosis cells in late passage may generate misleading results since differences from control lines may be ascribed to generalized senile changes rather than to specific results of the cystic fibrosis genotype.

Adolescent↗

Bioelectric properties of cystic fibrosis airways obtained at heart-lung transplantation.

BACKGROUND: The basic defect in cystic fibrosis centres on abnormal ion transport in affected tissues such as the respiratory tract. Heart-lung transplantation provides a limited supply of native lower airways from these patients. The feasibility of in vitro studies of bioelectric properties and ion fluxes in lower airways, obtained at heart-lung transplantation from patients with cystic fibrosis, has been assessed. Comparison was made with airways from patients without cystic fibrosis. METHODS AND RESULTS: Tissue segments were mounted in Ussing chambers under open circuit conditions. The basal potential difference in tissues from nine patients with cystic fibrosis was -3.6 mV (SE 0.3 mV), not different from tissues from 12 patients without cystic fibrosis of -3.6 mV (0.5 mV). Amiloride (10 microM) caused a significantly greater fall in potential difference in bronchi from patients with cystic fibrosis (83.5% (SE 2.9%)) than in those from controls (55.1% (7.1%)). Isoprenaline (100 microM) produced no significant change in bioelectric properties in non-cystic fibrosis tissues, but induced a 26.2% (6.3%) increase in potential difference in cystic fibrosis airways. The latter response was reduced by amiloride pretreatment. Mucosal chloride substituted Krebs-Henseleit solution caused no change in bioelectric properties in cystic fibrosis airways. Sodium substituted Krebs solution produced a substantial fall in potential difference similar in magnitude to that seen after amiloride. Isotropic flux measurements showed no significant differences between non-cystic fibrosis and cystic fibrosis airways. No net movement of Na+ or Cl- was detected under open circuit conditions in either group. CONCLUSIONS: Cystic fibrosis bronchi obtained at heart-lung transplantation provide a viable source of tissue for in vitro studies of bioelectric properties. The increased response to amiloride characteristic of the upper airways in cystic fibrosis is retained in these tissues, as is the reduced chloride conductance. Although no differences in isotopic fluxes were seen between non-cystic fibrosis and cystic fibrosis tissues, heavily infected airways from patients with cystic fibrosis may not be suitable for ion flux measurements.

Amiloride↗

B-lymphocyte function in cystic fibrosis.

The susceptibility of patients with cystic fibrosis to chronic, progressive bacterial pulmonary infections has not been adequately explained. We explored peripheral blood B-cell function in 21 cystic fibrosis patients and in normal controls. All patients were above 10 years of age, and chronically colonized with Pseudomonas aeruginosa. Spontaneous plaque-forming cells, which reflect B-cell differentiation into immunoglobulin-secreting cells in vivo, and plaque-forming cells formed after activation with pokeweed mitogen or staphylococci in vitro, were studied. Cystic fibrosis patients had significantly higher spontaneous plaque-forming cells than normal individuals. This difference was due to the increase of spontaneous plaque-forming cells than normal individuals. This difference was due to the increase of spontaneous plaque-forming cells in patients with less severe pulmonary disease, since patients with advanced pulmonary disease had numbers of circulating immunoglobulin-secreting cells, similar to normal individuals. Both groups of cystic-fibrosis patients have a significant impairment of B-cell differentiation in response to polyclonal activation in vitro. This functional abnormality could not be explained by the presence of increased numbers of adherent suppressor cells, or by the presence of increased suppression by T-lymphocytes. The implications of our data for the increased susceptibility to infection and for the development of antibody-mediated hypersensitivity reactions are discussed.

Adolescent↗

DeltaF508 heterozygosity in cystic fibrosis and susceptibility to asthma.

BACKGROUND: Cystic fibrosis is a recessive disorder mainly characterised by lung disease. We tested the hypothesis that individuals heterozygous for the common cystic fibrosis deltaF508 mutation are at risk of obstructive pulmonary disease. METHODS: We studied a cross-sectional sample from the general population of Copenhagen, Denmark, aged 20 years and older. We did spirometry to measure forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), and did genotyping on blood samples of 9141 individuals. We asked all participants whether they had asthma, and asked for information on smoking and other factors that could have contributed to obstructive pulmonary disease. FINDINGS: We identified 250 carriers of the deltaF508 mutation (2.7% [95% CI 2.5-3.1]). 9% of carriers reported having asthma compared with 6% of non-carriers (p=0.04). The odds ratio for asthma in participants heterozygous for deltaF508 mutation was 2.0 (1.2-3.5, p=0.02). Furthermore, among individuals with airway obstruction, the percentage predicted FEV1 and FVC were significantly lower in participants heterozygous for deltaF508 than in non-carriers (49 vs 58%, p=0.004; and 70 vs 82%, p<0.001, respectively), mainly due to an effect in those with self-reported asthma. INTERPRETATION: Cystic fibrosis deltaF508 heterozygosity may be over-represented among people with asthma and seems to be associated with decreased pulmonary function in people with airway obstruction who also have asthma.

Asthma↗

Laparoscopic cholecystectomy in adult cystic fibrosis.

Two female patients with Cystic Fibrosis, attending the Adult Regional Cystic Fibrosis centre at the Cork University Hospital, were investigated for upper abdominal pain and found to have gallstones at ultrasonography. Laparoscopic cholecystectomy was performed successfully and, without complication, in both patients.

Adult↗

Ocular findings in cystic fibrosis.

We examined 32 patients with cystic fibrosis, paying special attention to optic nerve performance and pupillary function. Decreased visual acuity occurred in nine of 64 eyes. Three of 17 patients (18%) who used chloramphenicol had bilaterally delayed P100 waves of the visual-evoked response of greater than 3 standard deviations. This was not found in patients who did not use chloramphenicol. Contrast sensitivity in patients with cystic fibrosis was decreased at every spatial frequency when compared to healthy controls. This decrease was noted in patients who did and did not use chloramphenicol, suggesting that chloramphenicol is not the only cause of decreased contrast sensitivity in cystic fibrosis. With pharmacologic pupil testing we determined that patients with cystic fibrosis display a preganglionic oculosympathetic paresis that corresponded to the disease severity, as measured by the Shwachman score.

Adolescent↗

Longitudinal study of Aspergillus fumigatus strains isolated from cystic fibrosis patients.

The colonization over time of cystic fibrosis patients by Aspergillus fumigatus was investigated using a DNA fingerprinting method. Aspergillus fumigatus isolates collected sequentially for more than one year from six patients with cystic fibrosis were typed by Southern blot hybridization with a repetitive DNA sequence. Each cystic fibrosis patient harbored several strains of Aspergillus fumigatus that were isolated recurrently over time. Isolates collected from a cystic fibrosis patient with aspergilloma displayed the same genotype, suggesting that the infection was due to a single strain. Continuous isolation of the same genotype in another cystic fibrosis patient, however, was not correlated clinically with an Aspergillus infection.

Adolescent↗

Variant cystic fibrosis phenotypes in the absence of CFTR mutations.

BACKGROUND: Cystic fibrosis is a life-limiting autosomal recessive disorder with a highly variable clinical presentation. The classic form involves characteristic findings in the respiratory tract, gastrointestinal tract, male reproductive tract, and sweat glands and is caused by loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR ) gene. Nonclassic forms of cystic fibrosis have been associated with mutations that reduce but do not eliminate the function of the CFTR protein. We assessed whether alteration in CFTR function is responsible for the entire spectrum of variant cystic fibrosis phenotypes. METHODS: Extensive genetic analysis of the CFTR gene was performed in 74 patients with nonclassic cystic fibrosis who had been referred by 34 medical centers. We evaluated two families that each included a proband without identified mutations and a sibling with nonclassic cystic fibrosis to determine whether there was linkage to the CFTR locus and to measure the extent of CFTR function in the sweat gland and nasal epithelium. RESULTS: Of the 74 patients studied, 29 had two mutations in the CFTR gene, 15 had one mutation, and 30 had no mutations. A final genotype of two mutations was more common among patients who had been referred after screening for common cystic fibrosis-causing mutations identified one mutation than among those who had been referred after screening had identified no such mutations (26 of 34 patients vs. 3 of 40 patients, P<0.001). Comparison of clinical features and sweat chloride concentrations revealed no significant differences among patients with two, one, or no CFTR mutations. Haplotype analysis in the two families revealed no linkage to CFTR. Although each of the affected siblings had elevated sweat chloride concentrations, measurements of cyclic AMP-mediated ion and fluid transport in the sweat gland and nasal epithelium demonstrated the presence of functional CFTR. CONCLUSIONS: Factors other than mutations in the CFTR gene can produce phenotypes clinically indistinguishable from nonclassic cystic fibrosis caused by CFTR dysfunction.

Adolescent↗

Cystic fibrosis transport regulator and its mRNA are expressed in human epidermis.

Cystic fibrosis transport regulator is a cAMP-dependent chloride channel protein. Normal (non cystic fibrosis) human epidermis stained positive for cystic fibrosis transport regulator as densely as did the eccrine sweat gland when three monoclonal antibodies for R (regulatory) and C (C-terminus) domains of cystic fibrosis transport regulator were used. All the layers of the epidermis took up staining uniformly. A peptide for C-epitope completely blocked the staining with monoclonal antibodies for C. Nested reverse transcription polymerase chain reaction of freshly isolated human epidermal fragments and the eccrine sweat glands amplified the cystic fibrosis transport regulator mRNA sequence derived from exons 13 and 14 to comparable extents. The 526 base pair antisense, but not sense, RNA probe derived from exons 10-13 stained cystic fibrosis transport regulator mRNA in both the epidermis and the sweat gland to a similar extent. In the epidermis, the cytoplasm of basal cells, stratum spinosum cells, and granular layer cells were all stained uniformly, but not corneocytes in the stratum corneum. In the sweat secretory coils, both clear and dark cells were stained but not the myoepithelium, with the dark cells staining more densely than the clear cells as in a previous study. In the duct, both luminal and basal ductal cells took up cystic fibrosis transport regulator staining uniformly but luminal cytoplasm of luminal ductal cells was devoid of cystic fibrosis transport regulator mRNA. Although the function of cystic fibrosis transport regulator in the epidermis is totally unknown, its recently proposed role as a universal regulator of a variety of cellular and membrane functions necessitates further studies on its regulation and function in health and disease.

Adult↗

Short stature and pubertal delay in cystic fibrosis.

Survival of the patient with cystic fibrosis has been considerably extended in the last two decades due to improved therapy of pulmonary infection, nutritional management, and an organized system of centralized care. Psychological and social aspects of cystic fibrosis may be intensified during adolescence: developing independence in the face of required daily care; developing self-esteem in the face of illness-associated problems such as discolored teeth, malabsorption, short stature, and cough; and participating in group activities despite physical limitations and the disruption in peer relationships when recurrent acute illness is interposed. Pubertal delay is more common in the cystic fibrosis population than the general population, and attendant psychologic dysfunction may be particularly common in males. Comparative studies suggest that this pubertal delay is a function of malnutrition rather than intrinsic to the disease. Normal growth potential may be postulated from somatomedin studies and has been demonstrated in patients treated with long-term aggressive nutritional management. Intervention utilizing testosterone enanthate in males with cystic fibrosis and pubertal delay has resulted in improved rate of growth, progression through puberty, and self-image.

Adolescent↗

Cystic fibrosis: molecular biology and therapeutic implications.

Cystic fibrosis is the most common potentially lethal autosomal recessive disease of Caucasians, affecting 1 in 2500 newborns. Since the recent identification of the gene that is defective in patients with cystic fibrosis, a wealth of information about gene structure, the mutational basis of disease, and the function of the protein product has been derived. The product of the gene is a chloride channel that is regulated by adenosine 3',5'-monophosphate (cyclic AMP)-dependent protein kinase phosphorylation and that requires binding of adenosine triphosphate (ATP) for channel opening. Several new approaches to drug therapy for cystic fibrosis are now emerging, and the possibility of successful gene therapy by transfer of the normal gene to airway epithelial cells is being vigorously pursued.

Chromosome Deletion↗

Studies in meconium. An approach to screening tests to detect cystic fibrosis.

Screening for cystic fibrosis (CF) in newborns is desirable, and efforts should continue in establishing a system of easily available, reliable, simple, and inexpensive tests. In addition to the Boehringer-Mannheim (BM) test for the detection of albumin, we propose the assay for lactase and beta-D-fucosidase in meconium. These latter two enzymes are present in the meconium of babies with CF and absent in meconium of most healthy babies. In a mass screening program for CF involving 20,182 specimens of meconium using only the BM strip, we found 46 positive results. Twenty-nine specimens came from infants with CF, six of whom had meconium ileus. Seventeen specimens yielded false-positive results by the BM test. Eleven of these would have been excluded by the addition of the lactase and beta-D-fucoside assay, thus reducing the false-positive test results by nearly 61%. In a comparative study of the three methods, the lactase and beta-D-fucosidase yielded 1.2% false-positives when examined independently. Performance of these two assays may allow greater specificity in diagnosis when used in addition to the BM test.

Albumins↗

Burkholderia and emerging pathogens in cystic fibrosis.

Persons with cystic fibrosis (CF) are susceptible to respiratory tract infection with a variety of bacterial species. Among these are several species in the genus Burkholderia (including members of the B. cepacia complex, B. gladioli, and B. pseudomallei), Stenotrophomonas maltophilia, Achromobacter ( Alcaligenes) xylosoxidans, certain Ralstonia species, and species within the new genus Pandoraea. Enterobacteriaceae and several other rather unusual or novel species also can be found. Many of these species are closely related phylogenetically and have similar phenotypes, presenting a challenge to accurate laboratory identification. Although their role in contributing to pulmonary disease in CF is not clear, the incidence of infection by some of these species appears to be increasing. The broad-spectrum antimicrobial resistance typically exhibited by these species severely limits treatment options. Newly developed genotypic methods of identification will enable studies to better assess the epidemiology and natural history of these emerging pathogens in CF.

Journal Article↗

Molecular epidemiology of Staphylococcus aureus strains colonizing the lungs of related and unrelated cystic fibrosis patients.

BACKGROUND: Cystic fibrosis (CF) patients can become persistently colonized with Staphylococcus aureus. This is initiated at an early age and may continue until or sometimes even during adolescence. Little is known about the epidemiology and cross-infectivity of S. aureus in CF patients, whether via the environment or person to person. METHODS: S. aureus isolates (n=189) from six unrelated CF patients and six pairs of CF siblings were genetically typed by arbitrary primed polymerase chain reaction (AP-PCR) assays. RESULTS: This longitudinal study revealed 35 different genotypes among the 189 isolates; the median number of types in a patient was three (range 1--6). One common S. aureus genotype was found in six patients and involved 20% of all isolates analyzed. Ultimately, in most of the patients long-term colonization with a single genotype was observed. In several, but certainly not all, pairs the siblings became persistently colonized with isolates that could not be discriminated by the typing method used; different S. aureus genotypes were isolated on an incidental but relatively frequent basis. Only one pair of siblings never shared identical isolates at any time during the screening period. CONCLUSIONS: In five of six cases, identical isolates were shared by CF siblings at a certain time. This suggests intra-family transmission or the presence of a common environmental source. The fact that in most of the CF sibling pairs different genotypes of S. aureus caused the ultimate long-term colonization indicates that, despite regular cross-colonization, patient characteristics select the S. aureus strain best adapted to the affected lung. Some genotypes may be particularly prevalent in the CF patient population, but additional studies are needed to confirm this.

Journal Article↗

Calcium-pump inhibitors induce functional surface expression of Delta F508-CFTR protein in cystic fibrosis epithelial cells.

The most common mutation in cystic fibrosis, Delta F508, results in a cystic fibrosis transmembrane conductance regulator (CFTR) protein that is retained in the endoplasmic reticulum (ER). Retention is dependent upon chaperone proteins, many of which require Ca(++) for optimal activity. Interfering with chaperone activity by depleting ER Ca(++) stores might allow functional Delta F508-CFTR to reach the cell surface. We exposed several cystic fibrosis cell lines to the ER Ca(++) pump inhibitor thapsigargin and evaluated surface expression of Delta F508-CFTR. Treatment released ER-retained Delta F508-CFTR to the plasma membrane, where it functioned effectively as a Cl(-) channel. Treatment with aerosolized calcium-pump inhibitors reversed the nasal epithelial potential defect observed in a mouse model of Delta F508-CFTR expression. Thus, ER calcium-pump inhibitors represent a potential target for correcting the cystic fibrosis defect.

Amiloride↗

Similarity of the tracheobronchial mucous glands and epithelium in infants with and without cystic fibrosis.

A retrospective study of 90 infants and young children with cystic fibrosis and 90 age matched controls without cystic fibrosis revealed no essential histologic differences in their tracheobronchial mucous gland reactions with and without pulmonary infection. Although the secretory response to specific stimuli (especially Pseudomonas or staphylococcal infection) varied in individual cases, every change seen in cystic fibrosis was present in the controls. Inactive or normally active mucous glands were usually present in the cystic fibrosis and control infants in the absence of infection. Moderate mucous gland activity in the absence of overt infection was not pathognomonic of cystic fibrosis; it was seen in both groups in response to an irritative stimulus, such as aspirated blood or gastric contents. Mucous gland secretions contained both acid and neutral mucins in the presence of infection, with no real distinction between the cystic fibrosis infants and controls, differing from the predominantly acid mucins in infected polyps of older children. Reparative squamous metaplasia in the tracheobronchial tract occurred more frequently in infants with cystic fibrosis than in controls. Although cystic fibrosis did predispose to progressive pulmonary disease (bronchiolitis, bronchiectasis), similar lung lesions were found in other metabolic and chronic disorders.

Bacterial Infections↗

New insights into the pathogenesis of cystic fibrosis: pivotal role of glutathione system dysfunction and implications for therapy.

The cystic fibrosis transmembrane regulator (CFTR) should no longer be viewed primarily as a 'chloride channel' but recognized as a channel that also controls the efflux of other physiologically important anions, such as glutathione (GSH) and bicarbonate. More effective approaches to cystic fibrosis treatment may result from this reconceptualization of the CFTR by researchers and clinicians. For example, oxidant damage in cystic fibrosis has been assumed to be a significant part of the pathophysiology of the disease. Generally speaking, antioxidant status in cystic fibrosis is compromised. However, until recently this was seen as secondary to the excessive chemoattraction of neutrophils in this disease caused by mutation of the CFTR protein, leading to a high oxidant burden. New findings suggest that the cystic fibrosis mutations in fact cause a primary dysfunction in the system of one of the body's most important antioxidant and immune-signaling substances: the reduced GSH system. Cystic fibrosis mutations significantly decrease GSH efflux from cells without redundant channels to the CFTR; this leads to deficiency of GSH in the epithelial lining fluid of the lung, as well as in other compartments, including immune system cells and the gastrointestinal tract. This deficiency is exaggerated over time as the higher-than-normal oxidant burden of cystic fibrosis leads to successively larger decrements in GSH without the normal opportunity to fully recover physiologic levels. This GSH system dysfunction may be the trigger for initial depletion of other antioxidants and may also play a role in initiating the over-inflammation characteristic of cystic fibrosis. Proper GSH system functioning also affects immune system competence and mucus viscosity, both of relevance to cystic fibrosis pathophysiology. In a way, cystic fibrosis may be thought of as the first identified disease with GSH system dysfunction.This overview provides a review of the most pertinent recent research findings in this area. Exogenous augmentation of GSH in the lung epithelial lining fluid is possible, and therapeutic approaches include administration of aerosolized buffered GSH, intravenous GSH, and oral GSH. However, it is important to remember that the pathophysiology of cystic fibrosis is multifactorial, and rectification of GSH system dysfunction in patients with cystic fibrosis will not eliminate all harmful effects of the disease. The promising results of two clinical trials of aerosolized buffered GSH in cystic fibrosis patients have been published or accepted for publication at the time of this writing. GSH depletion in lung epithelial lining fluid has also been noted in other respiratory diseases such as COPD, idiopathic pulmonary fibrosis, and adult respiratory distress syndrome, and therapies to augment GSH may also be contemplated in these diseases.

Cystic Fibrosis↗