Clinical patterns in asthma based on proximal and distal airway nitric oxide categories

<p>Abstract</p> <p>Background</p> <p>The exhaled nitric oxide (eNO) signal is a marker of inflammation, and can be partitioned into proximal [J'aw_NO(nl/s), maximum airway flux] and distal contributions [CA_NO(ppb), distal airway/alveolar NO concentration]. We hypothesized that J'aw_NOand CA_NOare selectively elevated in asthmatics, permitting identification of four inflammatory categories with distinct clinical features.</p> <p>Methods</p> <p>In 200 consecutive children with asthma, and 21 non-asthmatic, non-atopic controls, we measured baseline spirometry, bronchodilator response, asthma control and morbidity, atopic status, use of inhaled corticosteroids, and eNO at multiple flows (50, 100, and 200 ml/s) in a cross-sectional study design. A trumpet-shaped axial diffusion model of NO exchange was used to characterize J'aw_NOand CA_NO.</p> <p>Results</p> <p>J'aw_NOwas not correlated with CA_NO, and thus asthmatic subjects were grouped into four eNO categories based on upper limit thresholds of non-asthmatics for J'aw_NO(≥ 1.5 nl/s) and CA_NO(≥ 2.3 ppb): Type I (normal J'aw_NOand CA_NO), Type II (elevated J'aw_NOand normal CA_NO), Type III (elevated J'aw_NOand CA_NO) and Type IV (normal J'aw_NOand elevated CA_NO). The rate of inhaled corticosteroid use (lowest in Type III) and atopy (highest in Type II) varied significantly amongst the categories influencing J'aw_NO, but was not related to CA_NO, asthma control or morbidity. All categories demonstrated normal to near-normal baseline spirometry; however, only eNO categories with increased CA_NO(III and IV) had significantly worse asthma control and morbidity when compared to categories I and II.</p> <p>Conclusions</p> <p>J'aw_NOand CA_NOreveal inflammatory categories in children with asthma that have distinct clinical features including sensitivity to inhaled corticosteroids and atopy. Only categories with increase CA_NOwere related to poor asthma control and morbidity independent of baseline spirometry, bronchodilator response, atopic status, or use of inhaled corticosteroids.</p

Benthic community structure and ecosystem functions in above- and below-waterfall pools in Borneo

Waterfalls are geomorphic features that often partition streams into discrete zones. Our study examined aquatic communities, litter decomposition and periphyton growth rates for above- and below-waterfall pools in Ulu Temburong National Park, Brunei. We observed higher fish densities in below-waterfall pools (0.24 fish m−2 vs. 0.02 fish m−2 in above-waterfall pools) and higher shrimp abundance in above-waterfall pools (eight shrimp/pool vs. less than one shrimp/pool in below-waterfall pools). However, macroinvertebrate densities (excluding shrimp) were similar among both pool types. Ambient periphyton was higher in below-waterfall pools in 2013 (4.3 vs. 2.8 g m−2 in above-waterfall pools) and 2014 (4.8 vs. 3.4 g m−2 in above-waterfall pools), while periphyton growth rates varied from 0.05 to 0.26 g m−2 days−1 and were significantly higher in below-waterfall pools in 2014. Leaf litter decomposition rates (0.001 to 0.024 days−1) did not differ between pool types, suggesting that neither shrimp nor fish densities had consistent impacts on this ecosystem function. Regardless, this research demonstrates the varied effects of biotic and abiotic factors on community structure and ecosystem function. Our results have highlighted the importance of discontinuities, such as waterfalls, in tropical streams.</p