Reference values for exhaled nitric oxide in healthy children aged 6-18 years in China: a cross-sectional, multicenter clinical study.

BACKGROUND: The reference values of eNO have certain differences among people of different countries and races. We aimed to obtain the reference value of eNO in healthy children and adolescents (6-18 years old) in China and to explore the associations between the reference values with ages, gender, heights, BMI, and regions. METHODS: We measured FeNO50 levels in 5949 healthy Chinese children and adolescents, FeNO200 and CaNO levels in 658 participants from 16 provinces of 7 administrative areas in China aged 6-18. All persons were studied after obtaining informed consent from children and their parents. RESULTS: The mean FeNO50 of 5949 Chinese children and adolescents aged 6-18 years was 14.1 ppb, with a 95% confidence interval of 1-38.1 ppb. The mean FeNO200 of 658 persons was 6.9 ppb with a 95% upper confidence interval of 15.0 ppb, and the mean CaNO was 3.0 ppb with a 95% upper confidence interval of 11.2 ppb. In the 6-11 age group, age and height were correlated with the logarithm of FeNO50 (P < 0.001, P < 0.05). There was no significant correlation between the logarithm of FeNO200 and gender, age, height and BMI (all P > 0.05). The logarithm of CaNO was correlated with gender (P < 0.05). In the 12-18 age group, gender, height, and region were correlated with the logarithm of FeNO50 (all P < 0.001). There was only a weak correlation between the logarithm of FeNO200 and height (P < 0.001). The logarithm of CaNO was negatively correlated with age (P < 0.05). CONCLUSIONS: Higher FeNO50, FeNO200 and CaNO values were found in healthy children and adolescents in China compared with foreign reports, and is affected by age, height, gender, and region. This study provides useful references for clinical application of eNO in children, especially Asian children.

Prediction of asthma using a four-locus gene model including IL13, IL4, FCER1B, and ADRB2 in children of Kazak nationality.

BACKGROUND: To study whether the four locus gene model consisting of ADRB2 rs1042713, IL4 rs2243250, FCER1B rs569108 and L13 rs20541 can predict asthma of the Kazak children in Xinjiang, China. METHODS: Four single nucleotide polymorphisms about the 4 genes were genotyped in asthma group and control group of Han children and Kazak children respectively. The frequencies of different genotypes and alleles were compared between the asthma group and the control group in the two nationalities. Different risk genotypes for asthma were evaluated in the two nationalities. RESULTS: The differences about frequencies of genotypes in ADRB2 rs1042713 and IL4 rs2243250 and IL13 rs20541 between asthma group and control group were statistically significant in Han children, as were the frequencies of alleles in the 3 single nucleotide polymorphisms, but there were no statistical differences in FCER1B rs569108(P > 0.05). For the Kazak children, no differences were existed among all the genotypes and alleles in asthma group and control group. For the Han children, more children were asthma high risk genotype in the asthma group than those in the control group and no difference was found in the Kazak children. CONCLUSIONS: The four locus gene model consisting of ADRB2 rs1042713, IL4 rs2243250, FCER1B rs569108 and L13 rs20541 can predict asthma of Han children but not for the Kazak children in Xinjiang, which illustrating that the difference of asthma prevalence between different races is closely related to the genetic background.

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.

Stability analysis of Rayleigh-Bénard convection in a cylinder with internal heat generation.

The flow instabilities of Rayleigh-Bénard convection in a cylinder with effect of uniform internal heat source are investigated numerically. The instabilities of the static state and of axisymmetric flows are investigated by linear stability analysis. The convection threshold depends on the strength of internal heat source q and the aspect ratio of the cylinder Γ. The stability of axisymmetric flows is strongly affected by these two parameters, as well as the Prandtl number Pr. Depending on the value of q, three regimes are identified: weak internal heating, moderate internal heating, and strong internal heating regime. In a weak internal heating regime, the instability characteristics are similar to Rayleigh-Bénard convection. In a moderate internal heating regime, intense interaction of buoyancy instability and hydrodynamic instability result in complex instability curves. When q is large enough, the internal heating effect overwhelms the boundary heating effect. Specifically, the influence of Pr on instability is studied at a moderate internal heat strength q=6.4. An extremely multivalued stability curve is observed. At most five critical Rayleigh numbers can be determined for the axisymmetry-breaking instability at a certain Prandtl number. An axisymmetric unsteady instability mode is observed as well. By nonlinear simulation, the oscillatory flow patterns are obtained, and the axisymmetry-breaking bifurcation of the unsteady toroidal flow is studied.

Rayleigh-Bénard convection in a vertical annular container near the convection threshold.

The instabilities and transitions of flow in an annular container with a heated bottom, a cooled top, and insulated sidewalls are studied numerically. The instabilities of the static diffusive state and of axisymmetric flows are investigated by linear stability analysis. The onset of convection is independent of the Prandtl number but determined by the geometry of the annulus, i.e., the aspect ratio Γ (outer radius to height) and radius ratio δ (inner radius to outer radius). The stability curves for onset of convection are presented for 0.001≤δ≤0.8 at six fixed aspect ratios: Γ=1, 1.2, 1.6, 1.75, 2.5, and 3.2. The instability of convective flow (secondary instability), which depends on both the annular geometry and the Prandtl number, is studied for axisymmetric convection. Two pairs of geometric control parameters are chosen to perform the secondary instability analysis-Γ=1.2, δ=0.08 and Γ=1.6, δ=0.2-and the Prandtl number ranges from 0.02 to 6.7. The secondary instability exhibits some similarities to that for convection in a cylinder. A hysteresis stability loop is found for Γ=1.2, δ=0.08 and frequent changes of critical mode with Prandtl number are found for Γ=1.6, δ=0.2. The three-dimensional flows beyond the axisymmetry-breaking bifurcations are obtained by direct numerical simulation for Γ=1.2, δ=0.08.

Multiplicity of steady states in cylindrical Rayleigh-Bénard convection.

Three-dimensional steady Rayleigh-Bénard convection in a vertical cylinder is investigated by numerical simulation and bifurcation analysis. The complex pattern formation beyond the onset of the convection is presented by a bifurcation diagram. The coexistence of multiple stable states is observed near the threshold of the first bifurcation and two group symmetries are summarized for the corresponding primary branches. The first stable target pattern originates through a subcritical bifurcation. A multiplicity of flow states for the Rayleigh number of 14200 is validated numerically in comparison with the experiment, and a four-spoke pattern is observed.