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Khoo V, Pabary R, Lund Palau H, Turnbull A, Madden N, Schelenz S, Jones A, Morales S, Alton EWFW, Davies JC. S112 Variability in susceptibility to antibiotics and bacteriophages between individual colonies of Pseudomonas aeruginosa from cystic fibrosis sputum samples: implications for future clinical trial design. Thorax 2015. [DOI: 10.1136/thoraxjnl-2015-207770.118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Kent L, Reix P, Innes JA, Zielen S, Le Bourgeois M, Braggion C, Lever S, Arets HGM, Brownlee K, Bradley JM, Bayfield K, O'Neill K, Savi D, Bilton D, Lindblad A, Davies JC, Sermet I, De Boeck K. Lung clearance index: evidence for use in clinical trials in cystic fibrosis. J Cyst Fibros 2013; 13:123-38. [PMID: 24315208 DOI: 10.1016/j.jcf.2013.09.005] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/10/2013] [Accepted: 09/23/2013] [Indexed: 02/09/2023]
Abstract
The ECFS-CTN Standardisation Committee has undertaken this review of lung clearance index as part of the group's work on evaluation of clinical endpoints with regard to their use in multicentre clinical trials in CF. The aims were 1) to review the literature on reliability, validity and responsiveness of LCI in patients with CF, 2) to gain consensus of the group on feasibility of LCI and 3) to gain consensus on answers to key questions regarding the promotion of LCI to surrogate endpoint status. It was concluded that LCI has an attractive feasibility and clinimetric properties profile and is particularly indicated for multicentre trials in young children with CF and patients with early or mild CF lung disease. This is the first article to collate the literature in this manner and support the use of LCI in clinical trials in CF.
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Pabary R, Kumar S, Huang J, Alton EWFW, Bush A, Hanna GB, Davies JC. S9 SIFT-MS analysis as a non-invasive determinant of pseudomonas aeruginosa infection in patients with cystic fibrosis. Thorax 2013. [DOI: 10.1136/thoraxjnl-2013-204457.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Anastasopoulos A, Davies JC, Hannah L, Hayden BE, Lee CE, Milhano C, Mormiche C, Offin L. The particle size dependence of the oxygen reduction reaction for carbon-supported platinum and palladium. CHEMSUSCHEM 2013; 6:1973-1982. [PMID: 24115683 DOI: 10.1002/cssc.201300208] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/04/2013] [Indexed: 06/02/2023]
Abstract
Model carbon supported Pt and Pd electrocatalysts have been prepared using a high-throughput physical vapor deposition method. For Pt, metal particle sizes are controlled between 1.5-5.5 nm over 100 electrodes of an electrochemical screening chip, allowing the oxygen reduction reaction (ORR) activity of the catalysts to be determined simultaneously. The ORR-specific current density is observed to increase with increasing particle diameter up to approximately 4 nm, at which point the activity begins to level off. The reduction in ORR activity for particles below 4 nm is accompanied by a concomitant increase in the overpotential for surface reduction. The resulting mass activity exhibits a maximum for particles with diameters of approximately 3.5 nm. These results are consistent with results published recently for high area carbon-supported Pt catalysts. For Pd particles, both the specific current density and the mass-specific activity for the ORR are observed to increase with increasing particle diameter, with no distinct optimum observed. The implications for the optimization of Pt- or Pd-based ORR catalysts for proton exchange membrane fuel cell (PEMFC) applications are discussed.
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Thursfield RM, Bush A, Alton EWFW, Davies JC. S83 Levels of Antimicrobial Peptides in the Airway of Children with Cystic fibrosis are not related to Serum Vitamin D Concentration. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Griesenbach U, Inoue M, Meng C, Farley R, Chan M, Newman NK, Brum A, You J, Kerton A, Shoemark A, Boyd AC, Davies JC, Higgins TE, Gill DR, Hyde SC, Innes JA, Porteous DJ, Hasegawa M, Alton EWFW. P95 Assessment of F/HN-pseudotyped Lentivirus as a Clinically Relevant Vector For Lung Gene Therapy. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Simmonds N, Pabary R, Ya-Tung I, Bilton D, Alton EWFW, Davies JC. S123 The Role of Nasal Potential Difference Testing in Difficult Cases of Possible Cystic Fibrosis. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Alton EWFW, Ashby D, Boyd C, Cheng S, Cunningham S, Davies JC, Gill D, Griesenbach U, Higgins T, Hyde S, Innes JA, Murray G, Porteous D. S120 Update on the UK CF Gene Therapy Consortium Multidose, Non-Viral, Gene Therapy Trial. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Thursfield RM, Bush A, Alton EWFW, Davies JC. S82 Airway Inflammation is Present by 4 Months in CF Infants Diagnosed on Newborn Screening. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Pabary R, Singh C, Morales S, Bush A, Alshafi K, Bilton D, Alton EWFW, Smithyman A, Davies JC. S103 Anti-Pseudomonal Bacteriophage Cocktail Reduces Inflammatory Responses in the Murine Lung. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Davies JC. Enquiries into health and safety in South African mines in the 20th century: what did they have to say about occupational lung disease? ADLER MUSEUM BULLETIN 2010; 36:8-16. [PMID: 21949964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Fidler KJ, Hilliard TN, Bush A, Johnson M, Geddes DM, Turner MW, Alton EWFW, Klein NJ, Davies JC. Mannose-binding lectin is present in the infected airway: a possible pulmonary defence mechanism. Thorax 2008; 64:150-5. [PMID: 18988662 DOI: 10.1136/thx.2008.100073] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Mannose-binding lectin (MBL) deficiency has been associated with infections of the respiratory tract and with increased disease severity in cystic fibrosis (CF). The mechanism is uncertain, and could relate either to systemic or local effects. The aim of this study was to determine, in a large cohort of children, whether MBL is present on the airway surface in health or disease. METHODS Bronchoalveolar lavage (BAL) fluid from children with and without respiratory infection (some with underlying disease) was analysed for MBL and neutrophil elastase (NE). Levels were compared between groups, and correlations were examined with local and systemic inflammatory markers, infective organisms and load. RESULTS 85 children were recruited to the study. MBL was absent in the lavage of all 7 children without lung infection but present in 62% (8/13) of those with acute pneumonia/pneumonitis, 23% (5/22) with recurrent respiratory tract infections, 17% (1/6) with primary ciliary dyskinesia and 8% (3/37) with CF (p<0.01). Children with acute pneumonia/pneumonitis had significantly higher levels than those in the other groups. There was no relationship with organisms cultured or systemic markers of inflammation, although in the group with detectable MBL in the BAL fluid, the levels correlated positively with levels of NE. CONCLUSIONS MBL is undetectable in the non-infected airway but is present in a significant number of samples from children with lung infection. The levels found in the BAL fluid could be physiologically active and the protein may therefore be playing a role in host defence.
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Ryall B, Davies JC, Wilson R, Shoemark A, Williams HD. Pseudomonas aeruginosa, cyanide accumulation and lung function in CF and non-CF bronchiectasis patients. Eur Respir J 2008; 32:740-7. [PMID: 18480102 DOI: 10.1183/09031936.00159607] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In patients with cystic fibrosis (CF) and non-CF bronchiectasis, Pseudomonas aeruginosa is the most important respiratory pathogen. It is able to synthesise hydrogen cyanide, a potent inhibitor of cellular respiration. The present study investigated whether cyanide is present in the sputum of CF and non-CF bronchiectasis patients infected with P. aeruginosa, and whether the detection of cyanide affected lung function. Cyanide was measured in sputum using a cyanide ion selective electrode. Cyanide was detected in sputum from 15 out of 25 CF and non-CF bronchiectasis patients with current P. aeruginosa infection; however, it was not detected in any of the 10 patients without this organism. Maximum levels were 130 microM (mean+/-SE 72+/-6.6 microM). Concurrent lung function data were available on all 21 P. aeruginosa-infected CF patients; the group with measurable sputum cyanide (n = 11) was not different from those without (n = 10) on the basis of age or sex. However, those with detectable cyanide had significantly poorer lung function than those without (forced expiratory volume in one second (% predicted) 26.8+/-3.8 versus 46.0+/-6.7%; forced vital capacity (% pred) 44.4+/-4.9 versus 60.1+/-7.7%). Cyanide is detectable in sputum from cystic fibrosis and non-cystic fibrosis bronchiectasis patients infected with Pseudomonas aeruginosa, and is also associated with impaired lung function.
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Horsley AR, Gustafsson PM, Macleod KA, Saunders C, Greening AP, Porteous DJ, Davies JC, Cunningham S, Alton EWFW, Innes JA. Lung clearance index is a sensitive, repeatable and practical measure of airways disease in adults with cystic fibrosis. Thorax 2007; 63:135-40. [PMID: 17675315 DOI: 10.1136/thx.2007.082628] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Lung clearance index (LCI) is a sensitive marker of early lung disease in children but has not been assessed in adults. Measurement is hindered by the complexity of the equipment required. The aims of this study were to assess performance of a novel gas analyser (Innocor) and to use it as a clinical tool for the measurement of LCI in cystic fibrosis (CF). METHODS LCI was measured in 48 healthy adults, 12 healthy school-age children and 33 adults with CF by performing an inert gas washout from 0.2% sulfur hexafluoride (SF6). SF6 signal:noise ratio and 10-90% rise time of Innocor were compared with a mass spectrometer used in similar studies in children. RESULTS Compared with the mass spectrometer, Innocor had a superior signal:noise ratio but a slower rise time (150 ms vs 60 ms) which may limit its use in very young children. Mean (SD) LCI in healthy adults was significantly different from that in patients with CF: 6.7 (0.4) vs 13.1 (3.8), p<0.001. Ten of the patients with CF had forced expiratory volume in 1 s > or = 80% predicted but only one had a normal LCI. LCI repeats were reproducible in all three groups of subjects (mean intra-visit coefficient of variation ranged from 3.6% to 5.4%). CONCLUSIONS Innocor can be adapted to measure LCI and affords a simpler alternative to a mass spectrometer. LCI is raised in adults with CF with normal spirometry, and may prove to be a more sensitive marker of the effects of treatment in this group.
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Rosatte RC, Power MJ, Donovan D, Davies JC, Allan M, Bachmann P, Stevenson B, Wandeler A, Muldoon F. Elimination of arctic variant rabies in red foxes, metropolitan Toronto. Emerg Infect Dis 2007; 13:25-7. [PMID: 17370512 PMCID: PMC2725809 DOI: 10.3201/eid1301.060622] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To control the arctic variant of rabies virus in red foxes, 332,257 bait doses containing live, attenuated Evelyn-Rokitnicki-Abelseth rabies vaccine were distributed in greater metropolitan Toronto during 1989–1999. Human and pet contact with bait was minimal, and no adverse reactions to the vaccine were noted. Significantly fewer rabid foxes were found during the 17 years after fox baiting (5 cases during 1990–2006) than in the 17 years before (96 cases during 1973–1989). The last report of a rabid fox in metropolitan Toronto was in 1996 (reporting period through September 2006), which confirms that distributing oral rabies vaccine bait is a feasible tactic for the control of rabies in foxes in urban environments.
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Aziz ZA, Davies JC, Alton EW, Wells AU, Geddes DM, Hansell DM. Computed tomography and cystic fibrosis: promises and problems. Thorax 2007; 62:181-6. [PMID: 17287306 PMCID: PMC2111250 DOI: 10.1136/thx.2005.054379] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Computed tomography (CT) has two potential roles in the evaluation of patients with cystic fibrosis (CF) lung disease: as a diagnostic test primarily for the detection of supervening complications and as a monitoring tool in clinical research. Interest in the latter role has gained momentum in the last 5 years because of two factors: (1) therapeutic options for CF lung disease are developing rapidly, hence the need for an outcome measure that can be applied in clinical intervention trials; and (2) it has become clear that traditional outcome measures such as pulmonary function tests are relatively insensitive to the early structural damage that occurs in CF. Several recent studies have shown that CT can be used as a potential surrogate outcome measure, although its suitability for this specific role is controversial and still under investigation. This review summarises current concepts relating to the research applications of CT in CF, with particular emphasis on the evidence supporting the use of CT as a surrogate outcome measure in clinical trials.
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Molina-Teran A, Hilliard TN, Saglani S, Haxby E, Scallan M, Bush A, Davies JC. Safety of endobronchial biopsy in children with cystic fibrosis. Pediatr Pulmonol 2006; 41:1021-4. [PMID: 16998852 DOI: 10.1002/ppul.20365] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is little found in the published literature regarding the use of endobronchial biopsy (EBB) in children with cystic fibrosis (CF). One concern over the use of the technique may relate to safety, in particular increased risk of bleeding from a hypertrophied bronchial circulation. The aim of this retrospective study was to compare the safety of EBB in children with CF and those with other conditions, the most frequent of which included primary ciliary dyskinesia and recurrent lower respiratory tract infections. Case notes of all children undergoing EBB in our institution between February 2003 and May 2004 were reviewed. EBB was performed during 45 bronchoscopies in 42 CF patients (19 males, group mean age 7.13 +/- 4.48 years) and in 39 controls (20 males, group mean age 6.59 +/- 4.48 years). There were no significant differences between disease groups in the number, type, or severity of complications occurring during or in the first 12 hr after the procedure. We conclude that EBB performed as part of fibreoptic bronchoscopy (FOB) under general anaesthesia can be performed safely in children with CF, when both bronchoscopist and anaesthetist are suitably experienced. Studies of such samples would allow us to determine the early pathological changes in the CF airway and possibly find new treatments to prevent the progression to bronchiectasis and end stage airway destruction.
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Davies JC. Novel antipseudomonal treatment approaches. Arch Pediatr 2006; 13 Suppl 1:S51-4. [PMID: 17370397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Preventing and treating adequately Pseudomonas aeruginosa infection in the context of cystic fibrosis remains one of the most challenging topics of basic and clinical research in 2005. This state of the art review of antipseudomonal treatments describes some of the novel therapeutic approaches under development: active and passive immunisation, prevention of Pseudomonas aeruginosa adherence to cell surfaces, antibiofilm strategies, novel antimicrobial agents and inhaled dry powder antibiotics.
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Bilolikar H, Nam AR, Rosenthal M, Davies JC, Henderson DC, Balfour-Lynn IM. Tumour necrosis factor gene polymorphisms and childhood wheezing. Eur Respir J 2006; 26:637-46. [PMID: 16204594 DOI: 10.1183/09031936.05.00071104] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Tumour necrosis factor (TNF)-alpha is associated with childhood wheezing. A genetic predisposition to increased TNF-alpha production, influenced by single nucleotide gene polymorphisms, may be important. Frequencies of TNF-alpha-308G/A and lymphotoxin (LT)-alpha+252G/A polymorphisms were compared in 115 asthmatic children, 55 wheezy infants and 156 control school children from the UK. Genotype frequencies for the TNF-alpha-308 and LT-alpha+252 polymorphisms were significantly different from controls. Haplotype analysis showed that TNF-alpha-308G, LT-alpha+252A/TNF-alpha-308A, LT-alpha+252A was associated with a markedly increased risk for both asthma and infant wheezing. The TNF-alpha-308G, LT-alpha+252G/TNF-alpha-308G, LT-alpha+252A combination was protective for asthma and infant wheezing. These findings were confirmed by analysis of Caucasian data. Nasal TNF-alpha levels were measured in the infants during acute wheezing episodes and higher, but nonsignificant levels were produced in those with one or two LT-alpha+252A alleles. Unexpectedly, significantly lower nasal TNF-alpha levels were found in the presence of one or two TNF-alpha-308A alleles. TNF-alpha-308/LT-alpha+252 genotype combinations had a significant influence on nasal TNF-alpha levels. In conclusion, these findings may have implications for future early intervention studies by helping to identify infants at increased risk for wheezing and childhood asthma.
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Abstract
Although over 1,000 disease-causing mutations in the CFTR gene have been described, the highly variable disease phenotype in cystic fibrosis (CF) cannot be explained on the basis of this gene alone. Both the environment and other non-CFTR genes are likely to be important. The increased understanding of pathophysiological processes in the CF lung has led to several studies on genes in these pathways, including those involved in host defense, mucin production, and airway responsiveness. Additionally, candidate modifiers of the gastrointestinal manifestations of CF have been explored. One of the major aims of such studies is to produce targets for novel drug developments. This review will summarize the field to date and discuss some of the methodological issues important in the design and interpretation of such studies.
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Davies JC, Turner MW, Klein N. Impaired pulmonary status in cystic fibrosis adults with two mutated MBL-2 alleles. Eur Respir J 2005; 24:798-804. [PMID: 15516675 DOI: 10.1183/09031936.04.00055404] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mannose-binding lectin has recently been identified as a modifier of severity in cystic fibrosis, although studies have produced differing results and the mechanism of action remains unclear. The current authors have studied large cohorts of adults (n=298) and children (n=260) to explore this apparent relationship further. Adults with two structural mutations, but not heterozygotes, had significantly reduced lung function and oxygen saturations, more frequent hospital admissions and raised systemic inflammatory markers. This was not related to increased rates of infection with Pseudomonas aeruginosa, and there was no increased susceptibility to Burkholderia cepacia. None of these findings was mirrored in the paediatric cohort. In conclusion, severe mannose-binding lectin deficiency appears to be detrimental to cystic fibrosis adults, although heterozygotes are not affected. It is suggested that this is not related to impaired complement-mediated bacterial killing, and a link with the host inflammatory response is hypothesised. If mannose-binding lectin replacement is developed as a new approach to treatment for this disease, the present study would suggest that the small group of severely deficient patients with two structural mutations may be the group to benefit.
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McShane D, Davies JC, Wodehouse T, Bush A, Geddes D, Alton EWFW. Normal nasal mucociliary clearance in CF children: evidence against a CFTR-related defect. Eur Respir J 2004; 24:95-100. [PMID: 15293610 DOI: 10.1183/09031936.04.00097503] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Studies on mucociliary clearance (MCC) in cystic fibrosis (CF) have produced conflicting results. This study aimed to differentiate primary (ion transport-related) from secondary (inflammatory) causes of delayed MCC in CF. Nasal MCC was measured in 50 children (CF, primary ciliary dyskinesia (PCD) and no respiratory disease). Nasal lavage fluid was analysed for interleukin (IL)-8 and tumour necrosis factor-alpha. Similar measurements were obtained in adult CF patients with and without chronic sinusitis (CS). Children with CF had neither delayed MCC nor increased levels of cytokines. Conversely, children with PCD had prolonged MCC times (all >30 min) and significantly raised levels of IL-8. CS-positive CF adults had significantly slower MCC than CS-negative subjects, but IL-8 levels were low and similar in both groups. Decreased airway surface liquid and delayed mucociliary clearance are the postulated primary mechanisms in cystic fibrosis. However, the current study reports that cystic fibrosis children have normal nasal mucociliary clearance. Abnormalities appeared in cystic fibrosis adults with symptoms of chronic sinus disease, suggesting a secondary rather than primary phenomenon. Studies to explore this mechanism in the distal, more sparsely-ciliated airways could aid an understanding of pathogenesis and the development of new treatments.
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Davies G, McShane D, Davies JC, Bush A. Multiresistant Pseudomonas aeruginosa in a pediatric cystic fibrosis center: natural history and implications for segregation. Pediatr Pulmonol 2003; 35:253-6. [PMID: 12629620 DOI: 10.1002/ppul.10262] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It has been suggested that cystic fibrosis (CF) patients harboring multiresistant (MR) Pseudomonas aeruginosa (PA) should be seen in separate clinics. The aim of this study was to test the feasibility of this by longitudinally studying the consistency of isolates of MRPA in individuals. We analyzed all respiratory tract cultures undertaken in 1 year from a pediatric CF clinic population (n = 367). PA was classified as MR according to the definition of the American CF Foundation: resistance to all agents in at least two of the following groups of antibiotics: beta-lactams, aminoglycosides, and fluroquinolones. PA was cultured from 96 children during the year of study. Thirty-six were infected with at least one MR strain. Following initial identification of MRPA, MR in subsequent cultures was highly variable. Twenty-three of 36 patients had subsequent cultures in which PA was identified. However, 21 of 23 patients had at least one isolate that was not MR following detection of MRPA. The variability with time in isolation of MR strains from individuals demonstrates the potential difficulties in designing segregation policies based on antibiotic sensitivity patterns.
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Pantelidis P, Lagan AL, Davies JC, Welsh KI, du Bois RM. A single round PCR method for genotyping human surfactant protein (SP)-A1, SP-A2 and SP-D gene alleles. TISSUE ANTIGENS 2003; 61:317-21. [PMID: 12753670 DOI: 10.1034/j.1399-0039.2003.00038.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The genes coding for the human surfactant proteins (SP)-A and SP-D are located on chromosome 10q22-q23.1. SP-D is the product of a single gene whereas SP-A is the product of two highly homologous genes SP-A1 and SP-A2. Several single nucleotide polymorphisms (SNP) are present in the SP-A1, SP-A2 and SP-D genes. Because of this high degree of sequence homology between the SP-A1 and SP-A2 genes, current genetic analysis studies employ a nested PCR/radioactive hybridization or restriction fragment length polymorphism approach to initially isolate the genes and subsequently to detect the SNP in these isolates. In this manuscript, we report the primers and conditions of a sequence specific primer-PCR methodology that enables the identification of SP-A1, SP-A2 and SP-D gene allelic variants directly on genomic DNA material.
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McShane D, Davies JC, Davies MG, Bush A, Geddes DM, Alton EWFW. Airway surface pH in subjects with cystic fibrosis. Eur Respir J 2003; 21:37-42. [PMID: 12570106 DOI: 10.1183/09031936.03.00027603] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cystic fibrosis (CF) transmembrane conductance regulator protein can transport bicarbonate and may therefore regulate airway surface (AS) pH. Disturbances of AS pH could contribute to the pathophysiology of CF lung disease. Five studies were carried out including the following: study 1) nasal pH measurements were made in 25 CF and 10 non-CF adults using an antimony pH probe. Mean nasal pH was significantly lower in the CF group. Nasal potential difference may have been a confounding factor; study 2) in a fresh cohort of CF and non-CF subjects, no significant difference was found between the two groups using a gold pH probe; study 3) simultaneous nasal pH measurements were made in 15 CF and 15 non-CF adults using both probes. In the CF group, there was a trend for the antimony probe to read lower than the gold probe. In the non-CF group, the antimony probe read higher. The pH difference noted in study 1 related to technical factors; study 4) the effect of acute changes in serum acid/base balance on nasal pH was assessed in five non-CF adults. Nasal pH was not altered by either acute respiratory acidosis or alkalosis; study 5) nasal and lower airway pH was measured in five CF and six non-CF children. No difference was found between the groups. There was a correlation between nasal and lower airway pH. The authors conclude that airway surface pH does not differ between cystic fibrosis and noncystic fibrosis subjects and therefore, cystic fibrosis transmembrane conductance regulator may not play a major role in airway surface pH in vivo.
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