Reduced generation of multiple motile cilia (RGMC) is a rare mucociliary clearance disorder. Affected persons suffer from recurrent infections of upper and lower airways because of highly reduced numbers of multiple motile respiratory cilia. Here we report recessive loss-of-function and missense mutations in MCIDAS-encoding Multicilin, which was shown to promote the early steps of multiciliated cell differentiation in Xenopus. MCIDAS mutant respiratory epithelial cells carry only one or two cilia per cell, which lack ciliary motility-related proteins (DNAH5; CCDC39) as seen in primary ciliary dyskinesia. Consistent with this finding, FOXJ1-regulating axonemal motor protein expression is absent in respiratory cells of MCIDAS mutant individuals. CCNO, when mutated known to cause RGMC, is also absent in MCIDAS mutant respiratory cells, consistent with its downstream activity. Thus, our findings identify Multicilin as a key regulator of CCNO/FOXJ1 for human multiciliated cell differentiation, and highlight the 5q11 region containing CCNO and MCIDAS as a locus underlying RGMC.
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene containing a premature termination signal are expected to produce little or no CFTR chloride channels. It has been shown in vitro, that aminoglycoside antibiotics can increase the frequency of erroneous insertion of nonsense codons hence permitting the translation of CFTR alleles carrying missense mutations to continue reading to the end of the gene. This led to the appearance of functional CFTR channels at the apical plasma membrane. The aim of this research was to determine if topical application of gentamicin to the nasal epithelium of patients with cystic fibrosis (CF) carrying stop mutations can express, in vivo, functional CFTR channels. Nine CF patients carrying stop mutations (mean age 23 +/- 11 yr, range 12 to 46 yr) received gentamicin drops (0.3%, 3 mg/ml) three times daily intranasally for a total of 14 d. Nasal potential difference (PD) was measured before and after the treatment. Before gentamicin application all the patients had abnormal nasal PD typical of CF. After gentamicin treatment, significant repolarization of the nasal epithelium representing chloride transport was increased from -1 +/- 1 mV to -10 +/- 11 mV (p < 0. 001). In conclusion, gentamicin may influence the underlying chloride transport abnormality in patients with CF carrying stop mutations.
Background -Bronchial hyperreactivity to methacholine is present in children with asthma and other types of paediatric chronic obstructive pulmonary disease (COPD), while hyperreactivity to exercise is more specific for asthma. Adenosine 5'-monophosphate (AMP) is a potent bronchoconstrictor and, like exercise, may provoke asthma by activating mast cells. This study investigated the suitability of AMP as a specific challenge for asthma in children. Methods -Bronchial provocation challenges with methacholine and AMP were performed in a double blind fashion using tidal breathing in 51 children with asthma, 21 with paediatric COPD ofvarious types, and in 19 control children. Each subject also underwent a standardised exercise challenge after inhalation challenges were completed. Sensitivity and specificity curves were constructed and the intersection point of sensitivity and specificity for each type ofchallenge was determined. Results -When the asthmatic patients were compared with the children with COPD, the intersection points for AMP, exercise and methacholine were 90%, 85%, and 50%, respectively. When compared with the controls the same intersection points were 98%, 84%, and 92%, and when children with paediatric COPD were compared with controls they were 55%, 50%, and 82%. Conclusions -Methacholine distinguishes both asthma and paediatric COPD from controls with a sensitivity of 82-92%, but does not distinguish between asthma and paediatric COPD; exercise and AMP distinguish asthma from controls with a sensitivity and specificity of 84-98% but they also distinguish asthma from paediatric COPD with a sensitivity and specificity of 85-90%. AMP inhalation is a practical aid for diagnosing asthma and distinguishing it from COPD in children of all ages. (Thorax 1995;50:51 1-516)
Background: Bronchial provocation tests such as exercise, methacholine (MCH), and adenosine-59-monophosphate (AMP) challenges are used extensively in the diagnosis of asthma. A study was undertaken to determine whether exhaled nitric oxide (eNO) can be used to diagnose asthma in patients with non-specific respiratory symptoms and to compare this test with conventional provocation tests. Methods: Patients with non-specific respiratory symptoms and normal spirometric parameters were included in the study. eNO was measured and exercise, MCH and AMP challenges performed in all subjects. Patients were defined as asthmatic based on clinical follow up 24 months after testing. Results: Forty patients were considered asthmatic and 45 were not. The area under receiver operating characteristic curves gave values of 0.896 for eNO, 0.781 for exercise, 0.924 for MCH, and 0.939 for AMP (p = 0.033, 0.575 and 0.085 for eNO v exercise, MCH and AMP respectively). From our data, a cut off value of NO .7 ppb at a flow rate of 250 ml/s best differentiates between asthmatics and nonasthmatics (sensitivity 82.5%, specificity 88.9%). Optimal cut off values for other tests were exercise: DFEV 1 >10% (sensitivity 57.9%, specificity 100%); PC 20 -MCH: (3 mg/ml (sensitivity 87.5%, specificity 86.7%); and PC 20 -AMP: (150 mg/ml (sensitivity 89.5%, specificity 95.6%). Conclusions: Measurement of eNO can be used as a safe, simple and rapid test for the diagnosis of asthma and is as good as bronchial provocation tests.
The measurement of bronchial reactivity is an important aid in the diagnosis of asthma, but the technique using spirometry is not feasible in young children. The aim of the present study was to determine the efficacy and safety of a modification of the chest auscultation method in the assessment of bronchial reactivity to inhaled methacholine in young asthmatic children. One hundred forty-six young children with asthma (mean age, 4.3 yr) underwent bronchial challenges with nebulized methacholine using the auscultation method (PCW). The end point was defined as the appearance of wheezing, oxygen desaturation, or tachypnea. For comparison, 30 children and young adults with asthma underwent bronchial provocation with methacholine using spirometry (PC(20)). A positive response using the auscultation method was observed in 95.9% of the younger children, and wheezes alone or in combination with other signs appeared in 80.8% of them. The mean desaturation at the end point was 4.6% (PCW) and 5.0% (PC(20)), with a similar pattern in the two groups. Cough was not helpful in determining the end point. We conclude that the modified auscultation method is effective and safe, with wheeze appearing at the end point in the large majority of the children.
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