Primary ciliary dyskinesia: current state of the art

Primary Ciliary Dyskinesia Due to Microtubular Defects is Associated with Worse Lung Clearance Index

Purpose

Primary ciliary dyskinesia (PCD) is characterised by repeated upper and lower respiratory tract infections, neutrophilic airway inflammation and obstructive airway disease. Different ultrastructural ciliary defects may affect lung function decline to different degrees. Lung clearance index (LCI) is a marker of ventilation inhomogeneity that is raised in some but not all patients with PCD. We hypothesised that PCD patients with microtubular defects would have worse (higher) LCI than other PCD patients.

Methods

Spirometry and LCI were measured in 69 stable patients with PCD. Age at testing, age at diagnosis, ethnicity, ciliary ultrastructure, genetic screening result and any growth of Pseudomonas aeruginosa was recorded.

Results

Lung clearance index was more abnormal in PCD patients with microtubular defects (median 10.24) than those with dynein arm defects (median 8.3, p = 0.004) or normal ultrastructure (median 7.63, p = 0.0004). Age is correlated with LCI, with older patients having worse LCI values (p = 0.03, r = 0.3).

Conclusion

This study shows that cilia microtubular defects are associated with worse LCI in PCD than dynein arm defects or normal ultrastructure. The patient’s age at testing is also associated with a higher LCI. Patients at greater risk of obstructive lung disease should be considered for more aggressive management. Differences between patient groups may potentially open avenues for novel treatments.

Electronic supplementary material

The online version of this article (10.1007/s00408-018-0086-x) contains supplementary material, which is available to authorized users.

Lessons From Unilateral Loss of Cilia: Early Nasal Nitric Oxide Gas Mixing and the Role of Sinus Patency in Determining Nasal Nitric Oxide

Nasal nitric oxide (nNO) measurement is a diagnostic test for primary ciliary dyskinesia (PCD). Here, we have shown the development of unilateral PCD-like symptoms associated with low nNO. A 60-year-old man had been previously healthy but developed unilateral, severe pansinusitis. He required surgical drainage of all left sinuses, and biopsies showed loss of the ciliated epithelium. At 4 weeks, he had unilateral (left-sided), profuse, clear rhinorrhea characteristic of PCD, and his surgical ostia were all patent endoscopically. His left-sided nNO was less than the right side by 37 ± 1.2 nL/min; this difference decreased to 18 ± 0.87 nL/min at 5 weeks and was gone by 6 weeks when his symptoms resolved. Measurements of 2- and 10-second measurements, in addition to standard nNO measurements, identified this discordance. We conclude that nNO reflects, in part, the production of NO by the ciliated epithelium, not just in the absence or occlusion of sinuses. Early (nasal/sinus volume) measures may be better for diagnosing PCD in than standard, steady-state assays in certain populations.

Monocytes from patients with Primary Ciliary Dyskinesia show enhanced inflammatory properties and produce higher levels of pro-inflammatory cytokines

Patients with Primary Ciliary Dyskinesia (PCD) suffer from recurrent upper and lower airway infections due to defects in the cilia present on the respiratory epithelium. Since chronic inflammatory conditions can cause changes in innate immune responses, we investigated whether monocytes isolated from the peripheral blood of pediatric PCD patients respond differently to inflammatory stimuli, compared to monocytes from healthy children and adults. The receptor for C5a (C5aR) was upregulated in PCD, whereas expression levels of the leukocyte chemoattractant receptors CCR1, CCR2, CCR5, BLT1 and FPR1 on PCD monocytes were similar to those on monocytes from healthy individuals. Also in vitro migration of PCD monocytes towards the ligands of those receptors (CCL2, fMLP, C5a and LTB4) was normal. Compared to healthy children, PCD patients had a higher percentage of the non-classic monocyte subset (CD14+CD16++) in circulation. Finally, PCD monocytes produced higher levels of pro-inflammatory cytokines (IL-1β and TNF-α) and chemokines (CCL3, CCL5, CCL18 and CCL22) in response to LPS, peptidoglycan and/or dsRNA stimulation. These data suggest that monocytes might exacerbate inflammatory reactions in PCD patients and might maintain a positive feedback-loop feeding the inflammatory process.

Primary ciliary dyskinesia: mechanisms and management

Primary ciliary dyskinesia is a genetically heterogeneous disorder of motile cilia that is predominantly inherited in an autosomal-recessive fashion. It is associated with abnormal ciliary structure and/or function leading to chronic upper and lower respiratory tract infections, male infertility, and situs inversus. The estimated prevalence of primary ciliary dyskinesia is approximately one in 10,000-40,000 live births. Diagnosis depends on clinical presentation, nasal nitric oxide, high-speed video-microscopy analysis, transmission electron microscopy, genetic testing, and immunofluorescence. Here, we review its clinical features, diagnostic methods, molecular basis, and available therapies.

Secondary defects detected by transmission electron microscopy in primary ciliary dyskinesia diagnostics

Primary ciliary dyskinesia (PCD) is predominantly an autosomal recessively inherited condition that affects ~1 in 15,000 people. Diagnosis of PCD can be complex and is ordinarily based on the results of multiple investigations. These investigations include nasal nitric oxide, high-speed video microscopy, genotyping, and electron microscopy analysis of ciliary ultrastructure. A diagnosis is ultimately confirmed by the presence of a hallmark defect identified by transmission electron microscopy or biallelic variants in a known PCD gene. Secondary ciliary defects are commonly seen in samples submitted for diagnosis of PCD. Acquired secondary ciliary ultrastructural abnormalities, which are not caused by a variant in a ciliary gene, are usually transient and reversible however failure to separate primary versus secondary defects can lead to misdiagnosis. In this review, we describe causes of secondary ciliary defects, identify the ultrastructural appearances associated with secondary ciliary dyskinesia and finally suggest methods to avoid misdiagnosis of PCD due to these acquired ciliary defects.

Movement

Primary ciliary dyskinesia is an inherited disease characterized by impaired ciliary function leading to diverse clinical manifestations, including chronic sinopulmonary disease, persistent middle ear effusions, laterality defects, and infertility. Our understanding of the complex genetics and functional phenotypes of primary ciliary dyskinesia has rapidly grown, and over 35 disease-associated genes have been identified, which segregate into genes that encode axonemal motor proteins, regulatory proteins within the cilium, and cytoplasmic proteins involved in ciliary assembly. These findings have yielded unexpected insights into the clinical heterogeneity of disease and are beginning to revolutionize diagnostic testing for primary ciliary dyskinesia.

Clinical impact of Pseudomonas aeruginosa colonization in patients with Primary Ciliary Dyskinesia

BACKGROUND

Airway infections in Primary Ciliary Dyskinesia (PCD) are caused by different microorganisms, including pseudomonas aeruginosa (PA). The aim of this study was to investigate the association of PA colonization and the progression of lung disease in PCD.

METHODS

Data from 11PCD centers were retrospectively collected from 2008 to 2013. Patients were considered colonized if PA grew on at least two separate sputum cultures; otherwise, they were classified as non-colonized. These two groups were compared on the lung function computed tomography (CT) Brody score and other clinical parameters.

RESULTS

Data were available from 217 patients; 60 (27.6%) of whom were assigned to the colonized group. Patients colonized with PA were older and were diagnosed at a later age. Baseline forced expiratory volume at 1 s (FEV₁) was lower in the colonized group (72.4 ± 22.0 vs. 80.1 ± 18.9, % predicted, p = 0.015), but FEV₁ declined throughout the study period was similar in both groups. The colonized group had significantly worse CT-Brody scores (36.07 ± 24.38 vs. 25.56 ± 24.2, p = 0.034). A subgroup analysis with more stringent definitions of colonization revealed similar results.

CONCLUSIONS

Lung PA colonization in PCD is associated with more severe disease as shown by the FEV₁ and CT score. However, the magnitude of decline in pulmonary function was similar in colonized and non-colonized PCD patients.

Primary ciliary dyskinesia presenting with spontaneous pneumothorax: Case report and review of the literature

BACKGROUND

Primary ciliary dyskinesia (PCD) is an autosomal recessive heterogeneous group of conditions with variable clinical findings.

CASE PRESENTATION

A 36-year-old nonsmoking Chinese man present to the emergency department of our hospital with acute-onset breathlessness and sudden-onset left-sided chest pain. The patient had 6 years primary infertility and suffered from recurrent episodes of respiratory tract infections since childhood. Chest X-ray was performed, which showed a left-sided pneumothorax with lung collapse. His conditions improved in clinical symptoms after 3 days of closed thoracic drainage. Radiographic findings after lung recruitment revealed bronchiectasis and bronchiolitis but no situs inversus. Paranasal sinus computed tomography (CT) showed maxillary sinusitis and ethmoid sinusitis. Pulmonary function tests demonstrated severe obstructive ventilation functional impairment. Bronchial mucosal cilia showed the absence of both outer and inner dynein arms of the microtubules (ODA and IDA). A culture of bronchoalveolar lavage fluid was positive for Pseudomonas aeruginosa. His clinical symptoms and CT images showed improvement after 1 month of treatment. A literature review revealed that few patients are diagnosed with PCD complicated with spontaneous pneumothorax. Within one year of follow-up, the patient showed good responses to local ICS+ LA beta₂ agonist combined with oral carbocistein.

CONCLUSIONS

Pneumothorax might be one of the complications of the PCD. Combination therapy including ICS+ LA beta₂ agonist and carbocistein could be a potential therapy to reduce the frequency of acute exacerbations and delay progression of PCD.

Respiratory manifestations in 38 patients with Alström syndrome

OBJECTIVES

Alström syndrome (AS) is a rare, multi-system condition characterized by retinal degeneration, sensorineural hearing loss, obesity, insulin-resistant diabetes, hypertriglyceridemia, cardiomyopathy, hepatorenal disease, and recurrent respiratory infections. It belongs to a group of genetic disorders known as primary ciliopathies, which includes autosomal dominant and recessive polycystic kidney diseases, as well as Joubert and Bardet-Biedl syndromes. Prior studies have suggested phenotypic overlap between primary ciliopathies affecting the non-motile, sensory cilia, and primary ciliary dyskinesia (PCD), a motile ciliopathy characterized by respiratory tract disease.

METHODS

We describe the burden of oto-sino-pulmonary disease in 38 individuals with AS and examines the degree of clinical overlap between PCD and AS. Evaluation at the NIH Clinical Center included clinical examination, chest imaging, and clinical history surveys, as well as measurement of nasal nitric oxide (nNO) in nine patients.

RESULTS

Recurrent otitis media was ubiquitous in the AS cohort (92%) with 50% requiring pressure equalization tube placement. A history of bronchitis/pneumonia and sinusitis was reported in 61% and 50% of individuals, respectively. PCD-characterizing symptoms (laterality defects, unexplained neonatal respiratory distress, year-round nasal congestion, and wet cough) were far less prevalent in the AS cohort compared to PCD, and the average nNO production in the AS cohort was 232 ± 57.1 nl/min compared to a cut-off of <77 nl/min for PCD.

CONCLUSIONS

These data suggest that the oto-sino-respiratory complications in AS are prominent enough to warrant increased clinical attention, but significantly impaired respiratory cilia function as seen in PCD is unlikely in AS. (www.clinicaltrials.gov, trial NCT00068224) Pediatr Pulmonol. 2017;52:487-493. © 2016 Wiley Periodicals, Inc.

Bacterial Pathogens and the Microbiome

Bacterial pathogens and microbiome alterations can contribute to the initiation and propagation of mucosal inflammation in chronic rhinosinusitis (CRS). In this article, the authors review the clinical and research implications of key pathogens, discuss the role of the microbiome, and connect bacteria to mechanisms of mucosal immunity relevant in CRS.

Assessment of ciliary phenotype in primary ciliary dyskinesia by micro-optical coherence tomography

Ciliary motion defects cause defective mucociliary transport (MCT) in primary ciliary dyskinesia (PCD). Current diagnostic tests do not assess how MCT is affected by perturbation of ciliary motion. In this study, we sought to use micro-optical coherence tomography (μOCT) to delineate the mechanistic basis of cilia motion defects of PCD genes by functional categorization of cilia motion. Tracheae from three PCD mouse models were analyzed using μOCT to characterize ciliary motion and measure MCT. We developed multiple measures of ciliary activity, integrated these measures, and quantified dyskinesia by the angular range of the cilia effective stroke (ARC). Ccdc39^-/- mice, with a known severe PCD mutation of ciliary axonemal organization, had absent motile ciliary regions, resulting in abrogated MCT. In contrast, Dnah5^-/- mice, with a missense mutation of the outer dynein arms, had reduced ciliary beat frequency (CBF) but preserved motile area and ciliary stroke, maintaining some MCT. Wdr69^-/- PCD mice exhibited normal motile area and CBF and partially delayed MCT due to abnormalities of ciliary ARC. Visualization of ciliary motion using μOCT provides quantitative assessment of ciliary motion and MCT. Comprehensive ciliary motion investigation in situ classifies ciliary motion defects and quantifies their contribution to delayed mucociliary clearance.

Interactions between Neutrophils and Pseudomonas aeruginosa in Cystic Fibrosis

Cystic fibrosis (CF) affects 70,000 patients worldwide. Morbidity and mortality in CF is largely caused by lung complications due to the triad of impaired mucociliary clearance, microbial infections and chronic inflammation. Cystic fibrosis airway inflammation is mediated by robust infiltration of polymorphonuclear neutrophil granulocytes (PMNs, neutrophils). Neutrophils are not capable of clearing lung infections and contribute to tissue damage by releasing their dangerous cargo. Pseudomonas aeruginosa is an opportunistic pathogen causing infections in immunocompromised individuals. P. aeruginosa is a main respiratory pathogen in CF infecting most patients. Although PMNs are key to attack and clear P. aeruginosa in immunocompetent individuals, PMNs fail to do so in CF. Understanding why neutrophils cannot clear P. aeruginosa in CF is essential to design novel therapies. This review provides an overview of the antimicrobial mechanisms by which PMNs attack and eliminate P. aeruginosa. It also summarizes current advances in our understanding of why PMNs are incapable of clearing P. aeruginosa and how this bacterium adapts to and resists PMN-mediated killing in the airways of CF patients chronically infected with P. aeruginosa.

The international primary ciliary dyskinesia cohort (iPCD Cohort): methods and first results

Data on primary ciliary dyskinesia (PCD) epidemiology is scarce and published studies are characterised by low numbers. In the framework of the European Union project BESTCILIA we aimed to combine all available datasets in a retrospective international PCD cohort (iPCD Cohort).

We identified eligible datasets by performing a systematic review of published studies containing clinical information on PCD, and by contacting members of past and current European Respiratory Society Task Forces on PCD. We compared the contents of the datasets, clarified definitions and pooled them in a standardised format.

As of April 2016 the iPCD Cohort includes data on 3013 patients from 18 countries. It includes data on diagnostic evaluations, symptoms, lung function, growth and treatments. Longitudinal data are currently available for 542 patients. The extent of clinical details per patient varies between centres. More than 50% of patients have a definite PCD diagnosis based on recent guidelines. Children aged 10–19 years are the largest age group, followed by younger children (≤9 years) and young adults (20–29 years).

This is the largest observational PCD dataset available to date. It will allow us to answer pertinent questions on clinical phenotype, disease severity, prognosis and effect of treatments, and to investigate genotype–phenotype correlations.

The iPCD Cohort offers a unique opportunity to study PCD in an international retrospective cohort of >3000 patientshttp://ow.ly/rn0m304Jgsu

Long-term outcome of Tunisian children with primary ciliary dyskinesia confirmed by transmission electron microscopy

BACKGROUND

Primary ciliary dyskinesia (PCD) is rare. Its diagnosis requires experienced specialists and expensive infrastructure. Its prognosis is variable.

OBJECTIVE

To study the long-term outcome of PCD in Tunisian children with ciliary ultra-structure defects detected by electron microscope.

METHODS

Covering a period of 20 years (1996-2015), this retrospective study included all patients with definite PCD (outer dynein arms (DA) defects and/or situs inversus) and presumed PCD (other ciliary ultra-structure defects). The clinical data and the investigations made were registered at diagnosis and during the follow-up.

RESULTS

Patients with a definite PCD (G1, n=7) were diagnosed earlier compared to those with a presumed PCD (G2, n=13) (2.5 vs. 9.3 years on average). At diagnosis, bronchiectasis was more frequent in G1 (3/7 vs. 4/13). The inner DA loss was constant in G1 and predominant in G2. The treatment adhesion was more often irregular in G2 (2/7 vs. 8/13). During a mean follow-up of 11 years, G1 showed less severe outcome (clubbing (0 vs. 3), bronchiectasis (3 vs. 11; more expanded in G2), proximal and distal airway obstruction (0/3 vs. 5/7), lobectomy (0 vs. 2), and death (0 vs. 2)).

CONCLUSION

Precocious diagnosis and regular treatment may enhance the PCD prognosis.

Diagnosis of Primary Ciliary Dyskinesia by a Targeted Next-Generation Sequencing Panel: Molecular and Clinical Findings in Italian Patients

Primary ciliary dyskinesia (PCD) is a rare genetic disorder that alters mucociliary clearance, with consequent chronic disease of upper and lower airways. Diagnosis of PCD is challenging, and genetic testing is hampered by the high heterogeneity of the disease, because autosomal recessive causative mutations were found in 34 different genes. In this study, we clinically and molecularly characterized a cohort of 51 Italian patients with clinical signs of PCD. A custom next-generation sequencing panel that enables the affordable and simultaneous screening of 24 PCD genes was developed for genetic analysis. After variant filtering and prioritization, the molecular diagnosis of PCD was achieved in 43% of the patients. Overall, 5 homozygous and 27 compound heterozygous mutations, 21 of which were never reported before, were identified in 11 PCD genes. The DNAH5 and DNAH11 genes were the most common cause of PCD in Italy, but some population specificities were identified. In addition, the number of unsolved cases and the identification of only a single mutation in six patients suggest further genetic heterogeneity and invoke the need of novel strategies to detect unconventional pathogenic DNA variants. Finally, despite the availability of mutation databases and in silico prediction tools helping the interpretation of variants in next-generation sequencing screenings, a comprehensive segregation analysis is required to establish the in trans inheritance and support the pathogenic role of mutations.

Mutations in DNAJB13, Encoding an HSP40 Family Member, Cause Primary Ciliary Dyskinesia and Male Infertility

Primary ciliary dyskinesia (PCD) is an autosomal-recessive disease due to functional or ultra-structural defects of motile cilia. Affected individuals display recurrent respiratory-tract infections; most males are infertile as a result of sperm flagellar dysfunction. The great majority of the PCD-associated genes identified so far encode either components of dynein arms (DAs), which are multiprotein-ATPase complexes essential for ciliary motility, or proteins involved in DA assembly. To identify the molecular basis of a PCD phenotype characterized by central complex (CC) defects but normal DA structure, a phenotype found in ∼15% of cases, we performed whole-exome sequencing in a male individual with PCD and unexplained CC defects. This analysis, combined with whole-genome SNP genotyping, identified a homozygous mutation in DNAJB13 (c.833T>G), a gene encoding a HSP40 co-chaperone whose ortholog in the flagellated alga Chlamydomonas localizes to the radial spokes. In vitro studies showed that this missense substitution (p.Met278Arg), which involves a highly conserved residue of several HSP40 family members, leads to protein instability and triggers proteasomal degradation, a result confirmed by the absence of endogenous DNAJB13 in cilia and sperm from this individual. Subsequent DNAJB13 analyses identified another homozygous mutation in a second family; the study of DNAJB13 transcripts obtained from airway cells showed that this mutation (c.68+1G>C) results in a splicing defect consistent with a loss-of-function mutation. Overall, this study, which establishes mutations in DNAJB13 as a cause of PCD, unveils the key role played by DNAJB13 in the proper formation and function of ciliary and flagellar axonemes in humans.

Study protocol, rationale and recruitment in a European multi-centre randomized controlled trial to determine the efficacy and safety of azithromycin maintenance therapy for 6 months in primary ciliary dyskinesia

Background

Clinical management of primary ciliary dyskinesia (PCD) respiratory disease is currently based on improving mucociliary clearance and controlling respiratory infections, through the administration of antibiotics. Treatment practices in PCD are largely extrapolated from more common chronic respiratory disorders, particularly cystic fibrosis, but no randomized controlled trials (RCT) have ever evaluated efficacy and safety of any pharmacotherapeutics used in the treatment of PCD. Maintenance therapy, with the macrolide antibiotic azithromycin, is currently widely used in chronic respiratory diseases including PCD. In addition to its antibacterial properties, azithromycin is considered to have beneficial anti-inflammatory and anti-quorum-sensing properties.

The aim of this study is to determine the efficacy of azithromycin maintenance therapy for 6 months on respiratory exacerbations in PCD. The secondary objectives are to evaluate the efficacy of azithromycin on lung function, ventilation inhomogeneity, hearing impairment, and symptoms (respiratory, sinus, ears and hearing) measured on a PCD-specific health-related quality of life instrument, and to assess the safety of azithromycin maintenance therapy in PCD.

Methods

The BESTCILIA trial is a European multi-centre, double-blind, randomized, placebo-controlled, parallel group study. The intervention is tablets of azithromycin 250/500 mg according to body weight or placebo administered three times a week for 6 months. Subjects with a confirmed diagnosis of PCD, age 7–50 years, are eligible for inclusion. Chronic pulmonary infections with Gram-negative bacteria or any recent occurrence of non-tuberculous mycobacteria are exclusion criteria. The planned number of subjects to be included is 125. The trial has been approved by the Research Ethics Committees of the participating institutions.

Discussion

We present a study protocol of an ongoing RCT, evaluating for the first time, the efficacy and safety of a pharmacotherapeutic treatment for patients with PCD. The RCT evaluates azithromycin maintenance therapy, a drug already commonly prescribed in other chronic respiratory disorders. Furthermore, the trial will utilize the Lung clearance index and new, PCD-specific quality of life instruments as outcome measures for PCD. Recruitment is hampered by frequent occurrence of Pseudomonas aeruginosa infection, exacerbations at enrolment, and the patients’ perception of disease severity and necessity of additional management and treatment during trial participation.

Trial registration

EudraCT 2013-004664-58 (date of registration: 2014-04-08).

Feasibility of lung clearance index in a clinical setting in pre-school children

Lung function testing in pre-school children in the clinical setting is challenging. Most cannot perform spirometry and many infant lung function tests require sedation. Lung clearance index (LCI) derived from the multiple-breath washout (MBW) test has been shown to be sensitive to early disease changes but may be time consuming and so a shortened test (LCI_0.5) may be more feasible in young children. We sought to establish feasibility of MBW in unsedated pre-school children in a clinic setting and hypothesised use of LCI_0.5 would increase success rates.116 pre-school children (28 healthy controls and 88 with respiratory disease), median age 4.0 years (range 2-6 years), underwent MBW tests unsedated in a clinic setting, using sulfur hexafluoride as a tracer gas and an adapted photoacoustic gas analyser.81 (70%) out of 116 children completed LCI and 72% completed LCI_0.5 measurement. Test success increased significantly in patients over 3 years (0% at <2.5 years, 33% at 2.5-3 years and 70% at >3 years, p<0.0001). LCI was elevated in those with respiratory disease compared with healthy controls.MBW is feasible in a clinic setting in unsedated pre-schoolers, particularly in those >3 years old, and LCI is raised in those with respiratory disease. Use of LCI_0.5 did not increase success rate in pre-schoolers.

A case of Kartagener syndrome with rhinolalia clausa

Kartagener syndrome is an autosomal recessive genetic ciliary disorder comprising of a classic triad of sinusitis, situs inversus and bronchiectasis. It's the one of primary ciliary dyskinesia disorders with manifestations present from childhood. Most patients of PCD have situs inversus. We present a case of 18 year-old women with recurrent lower and upper respiratory tracts infections, and rhinolalia clausa.

Nasal versus tracheobronchial biopsies to diagnose primary ciliary dyskinesia: A meta-analysis

OBJECTIVES/HYPOTHESIS

To systematically review the literature regarding the efficacy of different biopsy sites and methods to obtain an adequate ciliary sample for ultrastructural examination with electron microscopy (EM) for the diagnosis of primary ciliary dyskinesia (PCD).

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A literature search was conducted with respect to the diagnosis of PCD. English studies with five or more subjects were included. Successful biopsy was defined as an adequate ciliary sample to make or exclude the diagnosis of PCD.

RESULTS

Eight studies met inclusion criteria. These studies included 1,993 patients who underwent 2,299 ciliary biopsies. Included studies were level 3 or 4 evidence. The weighted pooled proportion of obtaining an adequate specimen from a nasal biopsy was 76% (95% confidence interval [CI], 64%-86%) versus 66% (95% CI, 62%-69%) for a tracheobronchial site (P = 0.10). The pooled proportion of obtaining an adequate sample was 68% for both brush and forceps biopsy groups (95% CI, 58%-77% and 54%-81%, respectively). Nasal scraping yielded a higher proportion of adequate specimens (pooled proportion of 92%; 95% CI, 82%-99%) than other techniques (P = 0.002).

CONCLUSION

Tissue biopsy is one component of diagnosing PCD. We found no significant difference between biopsy sites in terms of obtaining an adequate ciliary sample for EM evaluation. This suggests that nasal biopsy should be preferred for patients old enough to tolerate an office biopsy without the need for general anesthesia. The merits of nasal versus tracheobronchial biopsy in the operating room depend more on the risks and benefits of the procedure being performed.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:6-13, 2017.

[Primary ciliary dyskinesia]

Primary ciliary dyskinesia (PCD) is a rare disease, but causes symptoms that resemble far more common respiratory diseases. Late diagnosis is common, when damage to the respiratory system has already occurred. This article aims to elucidate the condition and the diagnostic methods available. The article is based on literature searches in PubMed and the author's own experience of patient treatment and clinical research.

Primary ciliary dyskinesia in adults

INTRODUCTION

Primary ciliary dyskinesia is an autosomal recessive genetic disorder leading to structural and/or functional abnormalities of motor cilia. Impaired mucociliary clearance is responsible for the development of a multi-organ disease, which particularly affects the upper and lower airways.

STATE OF THE ART

In adults, primary ciliary dyskinesia is mainly characterized by bronchiectasis and chronic ear and sinus disorders. Situs inversus is found in half of patients and fertility disorders are commonly associated. Diagnosis is based on specialized tests: reduced level of nasal nitric oxide concentrations is suggestive of primary ciliary dyskinesia, but only a nasal or bronchial biopsy/brushing with analysis of beat pattern by videomicroscopy and/or analysis of cilia morphology by electronic microscopy can confirm the diagnosis. However, the diagnosis is difficult to achieve due to the limited access to these specialized tests and to difficulties in interpreting them. Genetic tests are under development and may provide new diagnostic tools. Treatment is symptomatic, based on airway clearance techniques (e.g., physiotherapy) and systemic and/or inhaled antibiotics. Prognosis is related to the severity of the respiratory impairment, which can be moderate or severe.

PERSPECTIVES AND CONCLUSIONS

Diagnosis and management of primary ciliary dyskinesia remain poorly defined and should be supported by specialized centers to standardize the diagnosis, improve the treatment and promote research.

Recent advances in primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetic disease inherited in an autosomal recessive manner. The prevalence of PCD is estimated to be 1 in 20,000 live births. Congenital abnormality of the primary cilia results in situs inversus in 50% of patients. Decreased function of motile cilia causes chronic rhinosinusitis, otitis media with effusion, bronchiectasis and infertility. Cases with situs inversus are considered to show "Kartagener's syndrome", and diagnosis is not difficult. However, in cases without situs inversus, the diagnosis is much more troublesome. PCD without situs inversus is thus probably underdiagnosed. Prolonged chronic cough represents an important symptom that is seen in most patients. The diagnosis of PCD requires the presence of the characteristic clinical phenotypes and either: (1) specific ciliary ultrastructural defects identified by transmission electron microscopy in biopsy samples of respiratory epithelium; or (2) identification of mutation in one of the genes known to be associated with PCD. Nasal nitric oxide concentration is extremely low in PCD, and this could be useful for screening of the disease. At present, no fundamental therapies are available for PCD. Diagnosis in the early stages is important to prevent progression of bronchiectasis and deterioration of lung function by guidance for daily life, immunization, cessation of smoking and prompt therapy at the time of respiratory tract infection. Since PCD is inherited in an autosomal-recessive manner, genetic counseling is necessary after definite diagnosis.

Clinical value of measurement of pulmonary radioaerosol mucociliary clearance in the work up of primary ciliary dyskinesia

Background

We aimed to evaluate and define the general clinical applicability and impact of pulmonary radioaerosol mucociliary clearance (PRMC) on the work up of patients suspected of having primary ciliary dyskinesia (PCD). In addition, we wanted to evaluate the accuracy of the reference values used in the PRMC test.

Methods

Measurement of PRMC after inhalation of ^99mTc-albumin colloid aerosol was carried out on 239 patients (4–75 years of age) during a 9-year period. All were referred to the nuclear medicine department because of clinical suspicion of PCD. The results were compared primarily to results from nasal ciliary function testing, to electron microscopic (EM) examination of the ultrastructure of the cilia, and to the final clinical diagnosis.

Results

Of the 239 patients, 27 ended up with a final clinical diagnosis of definitive PCD. No patients with a PRMC test that was normal or otherwise not consistent with PCD ended up with PCD as final clinical diagnosis (though a minority of patients in this group ended up unresolved in regard to PCD). Forty percent of patients with an abnormal PRMC test ended up with PCD as final clinical diagnosis. Furthermore, the PRMC test had a high rate of conclusive results (90 %). Children <14 years of age with normal PRMC measurements showed significantly faster lung clearance than adults with similarly normal PRMC measurements.

Conclusions

To this date, PRMC is the only test providing evaluation of the mucociliary clearance of the entire lung. Its greatest strength is its ability to reject a suspected PCD diagnosis with great certainty. In our material, this accounted for 2/3 of referred patients. In addition, the test has a high rate of conclusive results. According to our analyses, reference equations on children would benefit from updated data.

Nonsense mutation in coiled-coil domain containing 151 gene (CCDC151) causes primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal-recessive disorder characterized by impaired ciliary function that leads to subsequent clinical phenotypes such as chronic sinopulmonary disease. PCD is also a genetically heterogeneous disorder with many single gene mutations leading to similar clinical phenotypes. Here, we present a novel PCD causal gene, coiled-coil domain containing 151 (CCDC151), which has been shown to be essential in motile cilia of many animals and other vertebrates but its effects in humans was not observed until currently. We observed a novel nonsense mutation in a homozygous state in the CCDC151 gene (NM_145045.4:c.925G>T:p.[E309*]) in a clinically diagnosed PCD patient from a consanguineous family of Arabic ancestry. The variant was absent in 238 randomly selected individuals indicating that the variant is rare and likely not to be a founder mutation. Our finding also shows that given prior knowledge from model organisms, even a single whole-exome sequence can be sufficient to discover a novel causal gene.

Presentation of primary ciliary dyskinesia in children: 30 years' experience

AIM

Primary ciliary dyskinesia (PCD) is a rare (1:15,000) condition resulting in recurrent suppurative respiratory tract infections, progressive lung damage and hearing impairment. As the diagnosis is often delayed for years, the purpose of this study was to review the presenting features of children with PCD attending Australia's initial diagnostic PCD service over a 30-year period.

METHOD

A retrospective review of the symptoms of children diagnosed with PCD at Concord Hospital between 1982 and 2012 was undertaken.

RESULTS

One thousand thirty-seven paediatric patients were referred for assessment and underwent nasal ciliary brushing. Eighty-four (8.1%) had PCD based on microscopic analysis of nasal cilia. This included 81 with ciliary ultrastructural abnormalities demonstrated on electron microscopy and 3 with a suggestive phenotype, reduced ciliary beat frequency and a family history of PCD. The median age at diagnosis was 6.4 years (range 0.1 to 18.2 years). Forty-six per cent had situs abnormalities and 31% had a family member with PCD. Recurrent cough (81%), rhinosinusitis (71%), recurrent otitis media (49%) and neonatal respiratory distress (57%) were reported. Bronchiectasis at presentation was documented in 32%. Situs abnormalities and neonatal respiratory distress were present together in 26%.

CONCLUSION

PCD remains under-recognised by health-care workers. The combination of neonatal respiratory distress, chronic suppurative cough and rhinosinusitis was the most common documented symptom cluster at presentation in cases of PCD. A heightened awareness of the clinical features of the disease may help to lower the age at diagnosis, facilitate appropriate treatment and improve long-term outcomes.

Unique among ciliopathies: primary ciliary dyskinesia, a motile cilia disorder

Primary ciliary dyskinesia (PCD) is a ciliopathy, but represents the sole entity from this class of disorders that results from the dysfunction of motile cilia. Characterized by respiratory problems appearing in childhood, infertility, and situs defects in ~50% of individuals, PCD has an estimated prevalence of approximately 1 in 10,000 live births. The diagnosis of PCD can be prolonged due to a lack of disease awareness, coupled with the fact that symptoms can be confused with other more common genetic disorders, such as cystic fibrosis, or environmental insults that result in frequent respiratory infections. A primarily autosomal recessive disorder, PCD is genetically heterogeneous with >30 causal genes identified, posing significant challenges to genetic diagnosis. Here, we provide an overview of PCD as a disorder underscored by impaired ciliary motility; we discuss the recent advances towards uncovering the genetic basis of PCD; we discuss the molecular knowledge gained from PCD gene discovery, which has improved our understanding of motile ciliary assembly; and we speculate on how accelerated diagnosis, together with detailed phenotypic data, will shape the genetic and functional architecture of this disorder.

Laterality defects other than situs inversus totalis in primary ciliary dyskinesia: insights into situs ambiguus and heterotaxy

BACKGROUND

Motile cilia dysfunction causes primary ciliary dyskinesia (PCD), situs inversus totalis (SI), and a spectrum of laterality defects, yet the prevalence of laterality defects other than SI in PCD has not been prospectively studied.

METHODS

In this prospective study, participants with suspected PCD were referred to our multisite consortium. We measured nasal nitric oxide (nNO) level, examined cilia with electron microscopy, and analyzed PCD-causing gene mutations. Situs was classified as (1) situs solitus (SS), (2) SI, or (3) situs ambiguus (SA), including heterotaxy. Participants with hallmark electron microscopic defects, biallelic gene mutations, or both were considered to have classic PCD.

RESULTS

Of 767 participants (median age, 8.1 years, range, 0.1-58 years), classic PCD was defined in 305, including 143 (46.9%), 125 (41.0%), and 37 (12.1%) with SS, SI, and SA, respectively. A spectrum of laterality defects was identified with classic PCD, including 2.6% and 2.3% with SA plus complex or simple cardiac defects, respectively; 4.6% with SA but no cardiac defect; and 2.6% with an isolated possible laterality defect. Participants with SA and classic PCD had a higher prevalence of PCD-associated respiratory symptoms vs SA control participants (year-round wet cough, P < .001; year-round nasal congestion, P = .015; neonatal respiratory distress, P = .009; digital clubbing, P = .021) and lower nNO levels (median, 12 nL/min vs 252 nL/min; P < .001).

CONCLUSIONS

At least 12.1% of patients with classic PCD have SA and laterality defects ranging from classic heterotaxy to subtle laterality defects. Specific clinical features of PCD and low nNO levels help to identify PCD in patients with laterality defects.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00323167; URL: www.clinicaltrials.gov.

Clinical application of nasal nitric oxide measurement in pediatric airway diseases

Nitric oxide plays an important role in several physiological and pathophysiological processes in the respiratory tract. Different ways to measure nasal nitric oxide levels in children are currently available. The possibility of obtaining nasal nitric oxide measurement from relatively young children, combined with the availability of portable devices that can be used even in the office setting, opens new perspectives for nasal nitric oxide analysis in the pediatric daily practice. This review presents a synopsis about the current clinical applications of nasal nitric oxide measurement in the pediatric clinical practice. A total of 3,775 articles on the topic were identified, of which 883 duplicates were removed, and 2,803 were excluded based on review of titles and abstracts. Eighty-nine full text articles were assessed for eligibility and 32 additional articles were obtained from the reference lists of the retrieved studies. Since very low nasal nitric oxide levels are found in the majority of patients with primary ciliary dyskinesia, most publications support a central role for nasal nitric oxide to screen the disease, and indicate that it is a very helpful first-line tool in the real-life work-up in all age groups. Decreased nasal nitric oxide concentration is also typical of cystic fibrosis, even though nasal nitric oxide is not as low as in primary ciliary dyskinesia. In other upper airway disorders such as allergic rhinitis, rhinosinusitis, nasal polyposis, and adenoidal hypertrophy, clinical utility of nasal nitric oxide is still critically questioned and remains to be established. Since nNO determination is flow dependent, a general consensus from the major investigators in this area is highly desirable so that future studies will be performed with the same flow rate. A shared nNO methodology will enable to overcome the challenges that lie ahead in incorporating nNO measurement into the mainstream clinical setting of pediatric airway diseases.

Multicenter analysis of body mass index, lung function, and sputum microbiology in primary ciliary dyskinesia

BACKGROUND

No studies longitudinally, simultaneously assessed body mass index (BMI) and spirometry in primary ciliary dyskinesia (PCD).

METHODS

We determined BMI and spirometry in 158 PCD children and adolescents from London, UK (n = 75), Naples, Italy (n = 23) and Copenhagen, Denmark (n = 60) at first presentation and during follow-up. Annual BMI and spirometry were prospectively collected and analyzed over blocks of 2, 4, and 6 consecutive years. Sputum pathogens were recorded.

RESULTS

Age at first spirometry was 8.7 years (range, 4.2-17.4). Mean Z scores of first measured BMI, FEV1, FVC, and FEF(25-75) were 0.01, -1.37, -0.84, and -1.68, respectively. First spirometry was not more frequently impaired in patients referred at age ≥6 years than in those referred at preschool age (P = 0.13). There were no differences in slopes for BMI, FEV1, FVC, or FEF(25-75) over any time block. H. influenzae was the most common pathogen, isolated at least once in 65% of patients. P. aeruginosa was found in 58 subjects (37%) of whom 8 (5%) were chronically infected. Neither pathogens was associated with spirometry changes.

CONCLUSIONS

Preschool referral to a PCD center was not associated with better spirometry or BMI. PCD children and adolescents receiving centralized care show steady BMI and spirometry during medium term follow-up. There was a high prevalence of Pseudomonas aeruginosa infection, but the evolution of spirometry or BMI was not affected by this microorganism in medium term. Despite our longitudinal analysis showed no differences between the three centers, the assessment of spirometry and BMI over time represents a quality improvement tool. Future studies are needed to highlight the role of spirometry and BMI in long term PCD management and identify subgroups of patients with a higher risk of early lung failure or nutritional problems.

Primary ciliary dyskinesia: overlooked and undertreated in children

Primary ciliary dyskinesia (PCD) is a multi-organ disorder associated with chronic oto-sino-pulmonary disease, neonatal respiratory distress, situs abnormalities and reduced fertility. Repeated respiratory tract infections leads to the almost universal development of bronchiectasis. These clinical manifestations are a consequence of poorly functioning motile cilia. However, confirming the diagnosis is quite difficult and is often delayed, so the true incidence of PCD may be significantly higher than current estimates. Nasal nitric oxide has been earmarked as a useful screening tool for identifying patients, but its use is limited in pre-school-aged children. Due to the rarity of PCD, the evidence base for management is somewhat limited, and treatment regimens are extrapolated from other suppurative lung disorders, like cystic fibrosis.

Genetics, diagnosis, and future treatment strategies for primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder resulting in chronic oto-sino-pulmonary disease. While PCD is estimated to occur in 1 in 20,000 individuals, fewer than 1,000 patients in the US have a well-established diagnosis.

AREAS COVERED

We provide an overview of the clinical manifestations of PCD, describe the evolution of diagnostic methods, and critique the literature on management of PCD.

EXPERT OPINION

Although interest in clinical studies in non-CF bronchiectasis has increased in recent years, some of whom enroll patients with PCD, the literature regarding therapy for PCD as a distinct entity is lacking, as the numbers are small, and there have been no sub-analyses published. However, with improved screening and diagnostic methods, the development of clinical and research consortiums, and actively enrolling registries of PCD patients, the environment is conducive to perform longitudinal studies of disease course and therapeutic studies to alter that course.

Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome?

Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.

Traumatic brain injury-induced ependymal ciliary loss decreases cerebral spinal fluid flow

Traumatic brain injury (TBI) afflicts up to 2 million people annually in the United States and is the primary cause of death and disability in young adults and children. Previous TBI studies have focused predominantly on the morphological, biochemical, and functional alterations of gray matter structures, such as the hippocampus. However, little attention has been given to the brain ventricular system, despite the fact that altered ventricular function is known to occur in brain pathologies. In the present study, we investigated anatomical and functional alterations to mouse ventricular cilia that result from mild TBI. We demonstrate that TBI causes a dramatic decrease in cilia. Further, using a particle tracking technique, we demonstrate that cerebrospinal fluid flow is diminished, thus potentially negatively affecting waste and nutrient exchange. Interestingly, injury-induced ventricular system pathology resolves completely by 30 days after injury as ependymal cell ciliogenesis restores cilia density to uninjured levels in the affected lateral ventricle.

Overcoming challenges in the management of primary ciliary dyskinesia: the UK model

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease associated with bronchiectasis, chronic rhinosinusitis, infertility and situs inversus. Estimates of prevalence vary widely, but is probably between 1:10,000- 1:40,000 in most populations. A number of observational studies indicate that access to services to diagnose and manage patients with PCD vary both between and within countries. Diagnosis is often delayed and frequently missed completely. The prognosis of patients with PCD is variable, but evidence suggests that it is improved by early diagnosis and specialist care. This article briefly reviews the literature concerning PCD and the evidence that specialist care will improve healthcare outcomes. The article specifically refers to a new national service in the UK.

Primary Ciliary Dyskinesia: An Update on New Diagnostic Modalities and Review of the Literature

Primary ciliary dyskinesia (PCD) is a genetic condition affecting approximately 1 in 15,000-20,000 individuals, and the majority of cases exhibit an autosomal recessive inheritance pattern. However, genetic heterogenicity is seen in PCD and reflects the complexity of ciliary structure and biogenesis. There have been many recent advances in the diagnosis and management of PCD in the last few years, including advanced genetic sequencing, nasal nitric oxide assay, and ciliary motility tests. This article focuses on the ultrastructure and pathophysiology of ciliary dyskinesias, along with a review of clinical features, screening, and diagnostic tests. It also reflects upon the diagnostic challenge caused by the diverse clinical presentation, which will be of great value to pediatricians for considering PCD in their differential list, henceforth leading to early recognition and management, along with awareness of the recent advances in the field of genetics and other techniques for diagnosis of this condition.

Comparison of conventional pulmonary rehabilitation and high-frequency chest wall oscillation in primary ciliary dyskinesia

BACKGROUND

Enhancement of mucociliary clearance by pulmonary rehabilitation (PR) is advocated in primary ciliary dyskinesia (PCD). Our primary aim was to compare the efficacy and safety of postural drainage, percussion and vibration [conventional PR (CPR)], and high frequency chest wall oscillation (HFCWO) by studying change in pulmonary function. Our secondary aim was to evaluate patient preferences regarding the two methods.

METHODS

This was a controlled randomized crossover study. PCD patients between the ages of 7 and 18 years were assigned to two groups, first group performed airway clearance with CPR at hospital for 5 days and after a 2-day washout period HFCWO was applied to the same group at home. HFCWO was applied first to the other group and then these patients were hospitalized for CPR. The primary outcome measure of the study was pulmonary function test (PFT). The secondary outcomes were pulse arterial oxygen saturation (SpO2 ) and the perceived efficiency and comfort level.

RESULTS

PFT values of patients increased significantly after both PR methods (before/after): CPR: FVC: 77.0 ± 14.1/81.8 ± 13.0 (P = 0.002); FEV1 : 72.9 ± 14.8/78.7 ± 13.5 (P = 0.001); PEF: 73.8 ± 14.5/82.5 ± 14.5 (P = 0.001); FEF25-75 : 68.6 ± 27.6/74.9 ± 29.3 (P = 0.007).

HFCWO FVC

75.1 ± 15.3/80.3 ± 13.9 (P = 0.002); FEV1 : 71.4 ± 16/77.4 ± 14.6 (P = 0.001); PEF: 70.9 ± 18.0/78.3 ± 17.7 (P = 0.002); FEF25-75 : 70.5 ± 23.4/76.4 ± 25.6 (P = 0.006). There were no significant differences in % predicted FVC, FEV1 , PEF, and FEF25-75 increased values with CPR and HFCWO. HFCWO was found more comfortable (P = 0.04). Two PR methods were found efficient and no desaturation occurred during PR.

CONCLUSIONS

PFTs were significantly increased after both PR methods. There were no differences in PFTs and SpO2 between the CPR and HFCWO groups. Both PR methods were found efficient. HFCWO was found more comfortable. HFCWO may be an option in patients with chronic pulmonary disease and low adherence to PR.

Genetic Testing in the Diagnosis of Primary Ciliary Dyskinesia: State-of-the-Art and Future Perspectives

Primary ciliary dyskinesia (PCD) is a heterogeneous autosomal recessive condition affecting around 1:15,000. In people with PCD, microscopic motile cilia do not move normally resulting in impaired clearance of mucus and debris leading to repeated sinopulmonary infection. If diagnosis is delayed, permanent bronchiectasis and deterioration of lung function occurs. Other complications associated with PCD include congenital heart disease, hearing impairment and infertility. A small number of longitudinal studies suggest that lung function deteriorates before diagnosis of PCD but may stabilise following diagnosis with subsequent specialist management. Early diagnosis is therefore essential, but for a number of reasons referral for diagnostic testing is often delayed until older childhood or even adulthood. Functional diagnostic tests for PCD are expensive, time consuming and require specialist equipment and scientists. In the last few years, there have been considerable developments to identify genes associated with PCD, currently enabling 65% of patients to be identified by bi-allelic mutations. The rapid identification of new genes continues. This review will consider the evidence that early diagnosis of PCD is beneficial. It will review the recent advances in identification of PCD-associated genes and will discuss the role of genetic testing in PCD. It will then consider whether screening for PCD antenatally or in the new born is likely to become a feasible and acceptable for this rare disease.

Diagnostic accuracy of nitric oxide measurements to detect primary ciliary dyskinesia

BACKGROUND

Primary Ciliary Dyskinesia (PCD) is an orphan disease characterized by recurrent respiratory infections and an increased prevalence of situs inversus and male infertility. Low nasal Nitric Oxide (nNO) is used as a new test to diagnose PCD. The test sensitivity is good, but specificity has not been studied widely. Therefore, we evaluated the diagnostic accuracy of low nNO to diagnose PCD in a large cohort, including healthy patients and different disease controls.

MATERIALS AND METHODS

Nasal nitric oxide was measured during plateau exhalation against resistance (nNOplat) and during tidal breathing (nNOtid). Moreover, we measured fractional exhaled NO (FENO). We included 226 patients: 38 with PCD, 49 healthy controls, and 139 disease controls (cystic fibrosis, humoral immunodeficiency, and asthma).

RESULTS

The nNOplat cut-off value of 300 ppb provided the best sensitivity (89·5%) and specificity (87·3%) to detect PCD. There was overlap between PCD and disease controls: 16·5% of disease controls had a false-positive result. nNOtid correlated with nNOplat (r=0·912), but values differed (P=0·0001). The nNOtid cut-off of 200 ppb had a sensitivity of 89·5% and a specificity of 80·6% to detect PCD. The FENO cut-off of 10 ppb had an acceptable sensitivity (89·5%), but a low specificity (58·3%). Positive and negative likelihood ratios were suboptimal for all tests.

CONCLUSIONS

nNOplat, nNOtid and FENO measurements overlap between PCD and disease controls. Sensitivity is comparable for the three tests. Applying composite scores slightly improves diagnostic accuracy. Given the less than 90% test sensitivity, PCD should be considered in patients with intermediate results.

Dynamic interfacial behavior of viscoelastic aqueous hyaluronic acid: effects of molecular weight, concentration and interfacial velocity

An aqueous hyaluronic acid (HA(aq)) pericellular coat, when mediating the tactile aspect of cellular contact inhibition, has three tasks: interface formation, mechanical signal transmission and interface separation. To quantify the interfacial adhesive behavior of HA(aq), we induce simultaneous interface formation and separation between HA(aq) and a model hydrophobic, hysteretic Si-SAM surface. While surface tension γ remains essentially constant, interface formation and separation depend greatly on concentration (5 ≤ C ≤ 30 mg mL(-1)), molecular weight (6 ≤ MW ≤ 2000 kDa) and interfacial velocity (0 ≤ V ≤ 3 mm s(-1)), each of which affect shear elastic and loss moduli G′ and G′′, respectively. Viscoelasticity dictates the mode of interfacial motion: wetting-dewetting, capillary necking, or rolling. Wetting-dewetting is quantified using advancing and receding contact angles θ(A) and θ(R), and the hysteresis between them, yielding data landscapes for each C above the [MW, V] plane. The landscape sizes, shapes, and curvatures disclose the interplay, between surface tension and viscoelasticity, which governs interfacial dynamics. Gel point coordinates modulus G and angular frequency ω appear to predict wetting-dewetting (G < 75 ω0.2), capillary necking (75 ω0.2 < G < 200 ω0.075) or rolling (G > 200ω0.075). Dominantly dissipative HA(aq) sticks to itself and distorts irreversibly before separating, while dominantly elastic HA(aq) makes contact and separates with only minor, reversible distortion. We propose the dimensionless number (G′V)/(ω(r)γ), varying from 10(-5) to 10(3) in this work, as a tool to predict the mode of interface formation-separation by relating interfacial kinetics with bulk viscoelasticity. Cellular contact inhibition may be thus aided or compromised by physiological or interventional shifts in [C, MW, V], and thus in (G′V)/(ω(r)γ), which affect both mechanotransduction and interfacial dynamics. These observations, understood in terms of physical properties, may be broadened to probe interfacial dynamics of other viscoelastic aqueous biopolymers.

Primary ciliary dyskinesia diagnosed on nasal mucosal biopsy in two newborns

Primary ciliary dyskinesia (PCD) is a genetic disease that causes abnormalities in ciliary structure and/or function. Ciliated cells line the upper and lower respiratory tracts and the Eustachian tube. Impairment of mucus clearance at these sites leads to sinusitis, repeated pulmonary infections, bronchiectasis, and chronic otitis media. Situs inversus occurs randomly in approximately 50% of subjects with PCD. The triad of situs inversus, bronchiectasis and sinusitis is known as Kartagener syndrome. PCD is usually an autosomal recessive disease, but occasional instances of X-linked transmission have been reported. Specific diagnosis requires examination of ciliary function or structure on light and electron microscopy. Early diagnosis and respiratory management are important in order to prevent the development of bronchiectasis and deterioration in lung function. We report early diagnosis of PCD on nasal mucosal biopsy in two newborns who presented with prolonged respiratory distress and rhinorrhea.