Nitric oxide levels and ciliary beat frequency in indigenous New Zealand children

Nasal nitric oxide in healthy Chinese children aged 6-18 years

Objectives

To obtain the normal values of fractional concentration of nasal nitric oxide in Chinese children aged 6-18 years, so as to provide reference for clinical diagnosis.

Methods

2,580 out of 3,200 children (1,359 males and 1,221 females), whom were included from 12 centers around China were taken tests, their height and weight were also recorded. Data were used to analyze the normal range and influencing factors of fractional concentration of nasal nitric oxide values.

Measurements

Data was measured using the Nano Coulomb Breath Analyzer (Sunvou-CA2122, Wuxi, China), according to the American Thoracic Society/European Respiratory Society (ATS/ERS) recommendations.

Main Results

We calculated the normal range and prediction equation of fractional concentration of nasal nitric oxide values in Chinese children aged 6-18 years. The mean FnNO values of Chinese aged 6-18 yrs was 454.5 ± 176.2 ppb, and 95% of them were in the range of 134.5-844.0 ppb. The prediction rule of FnNO values for Chinese children aged 6-11 yrs was: FnNO = 298.881 + 17.974 × age. And for children aged 12-18 yrs was: FnNO = 579.222-30.332 × (male = 0, female = 1)-5.503 × age.

Conclusions

Sex and age were two significant predictors of FnNO values for Chinese children(aged 12-18 yrs). Hopefully this study can provide some reference value for clinical diagnosis in children.

Does Ethnicity Influence Fractional Exhaled Nitric Oxide in Healthy Individuals?: A Systematic Review

BACKGROUND

Fractional exhaled nitric oxide (Feno) is used clinically as a biomarker of eosinophilic airway inflammation. Awareness of the factors influencing Feno values is important for valid clinical interpretation.

METHODS

We undertook a systematic review of PubMed, Cochrane Library, Scopus, and Web of Science databases and reference lists of included articles to evaluate whether ethnicity influences Feno values, and to determine if this influence affects clinical interpretation according to current guidelines. We included all studies that performed online Feno measurements on at least 25 healthy, non-Caucasian individuals, and examined the effect of ethnicity on Feno.

RESULTS

From 62 potential studies, 12 studies were included. One study recruited only children (< 12 years of age), six studies recruited children and/or adolescents, four studies recruited adults only, and a single study involved children, adolescents, and adults. In total, 16 different ethnic populations representing 11 ethnicities were studied. Ethnicity was considered a significant influencing factor in 10 of the included studies. We found the geometric mean Feno to be above the normal healthy range in two studies. We also identified five studies in which at least 5% of participants had Feno results above the age-specific inflammatory ranges.

CONCLUSIONS

Ethnicity influences Feno values, and for some ethnic groups this influence likely affects clinical interpretation according to current guidelines. There is a need to establish healthy Feno reference ranges for specific ethnic groups to improve clinical application.

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.

Respiratory infections in Tamariki (children) and Taitamariki (young people) Māori, New Zealand

The Māori population is young, with 53% aged less than 25 years and with a higher prevalence of both acute (bronchiolitis, pneumonia, pertussis, tuberculosis) and chronic (bronchiectasis) respiratory tract infections than non-Māori. Environmental, economic and poorer access to health promotion programmes and health care rather than specific or genetic underlying disorders appear to contribute to this burden. While new initiatives are needed, we can do better with current public health programmes and building on regional initiatives that have already proven successful.

Initiation and maturation of cilia-generated flow in newborn and postnatal mouse airway

Mucociliary clearance in the adult trachea is well characterized, but there are limited data in newborns. Cilia-generated flow was quantified across longitudinal sections of mouse trachea from birth through postnatal day (PND) 28 by tracking fluorescent microsphere speed and directionality. The percentage of ciliated tracheal epithelial cells, as determined by immunohistochemistry, was shown to increase linearly between PND 0 and PND 21 (R(2) = 0.94). While directionality measurements detected patches of flow starting at PND 3, uniform flow across the epithelia was not observed until PND 7 at a approximately 35% ciliated cell density. Flow became established at a maximal rate at PND 9 and beyond. A linear correlation was observed between the percentage of ciliated cells versus flow speed (R(2) = 0.495) and directionality (R(2) = 0.975) between PND 0 and PND 9. Cilia beat frequency (CBF) was higher at PND 0 than at all subsequent time points, but cilia beat waveform was not noticeably different. Tracheal epithelia from a mouse model of primary ciliary dyskinesia (PCD) harboring a Mdnah5 mutation showed that ciliated cell density was unaffected, but no cilia-generated flow was detected. Cilia in mutant airways were either immotile or with slow dyssynchronous beat and abnormal ciliary waveform. Overall, our studies showed that the initiation of cilia-generated flow is directly correlated with an increase in epithelial ciliation, with the measurement of directionality being more sensitive than speed for detecting flow. The higher CBF observed in newborn epithelia suggests unique physiology in the newborn trachea, indicating possible clinical relevance to the pathophysiology of respiratory distress seen in newborn PCD patients.