Exhaled nitric oxide measurements in patients with acute-onset interstitial lung disease.

It is important to identify the underlying cause of acute-onset interstitial lung disease (ILD). This study aims to assess whether there are differences in the exhaled nitric oxide (eNO) level between different subtypes of acute-onset ILD. Forty patients with a combination of illness ≤4 weeks in duration and diffuse radiographic infiltrates were classified into groups based on the etiology. The eNO at a flow rate of 50 ml s-1 (FeNO), the alveolar nitric oxide concentration (Calv), and the systemic inflammatory markers of the groups were compared. The median FeNO value of patients with acute eosinophilic pneumonia (AEP) (48.1 ppb) was significantly higher than that of the other groups (17.4 ppb in cryptogenic organizing pneumonia, 20.5 ppb in hypersensitivity pneumonia, and 12.0 ppb for sarcoidosis) (p < 0.0005) as well as blood eosinophils (p < 0.005) and Calv levels (p < 0.005). The area under the receiver's operating characteristic curve (AUC) for FeNO to identify AEP was 0.90 with a cut-off of 23.4 ppb. The AUC for Calv and blood eosinophils was 0.85 and 0.82, respectively. Even in patients with blood eosinophil numbers <5 × 105 cells µl-1, FeNO maintained a good diagnostic value for AEP (AUC = 0.85). eNO can be useful for differentiating AEP from other types of acute-onset ILD, regardless of the blood eosinophil levels.

Persistently high exhaled nitric oxide and loss of lung function in controlled asthma.

BACKGROUNDS: It remains unclear whether a persistently high exhaled nitric oxide fraction (FeNO) in patients with controlled asthma is associated with the progressive loss of lung function. METHODS: This was a 3-year prospective study. We examined the changes in pre- and post-bronchodilator forced expiratory volume in 1 s (FEV1) and FeNO in 140 patients with controlled asthma. We initially determined the FeNO cut-off point for identifying patients with a rapid decline in FEV1 (>40 mL/yr). Next, a total of 122 patients who maintained high or non-high FeNO were selected, and the associations between the FeNO trend and changes in FEV1 and bronchodilator response (BDR) were investigated. RESULTS: A FeNO level >40.3 ppb yielded 43% sensitivity and 86% specificity for identifying patients with a rapid decline in FEV1. Patients with persistently high FeNO had higher rates of decline in FEV1 (42.7 ± 37.5 mL/yr) than patients with non-high FeNO (16.7 ± 31.5 mL/yr) (p < 0.0005). The changes in BDR from baseline to the end of the study, in patients who had high or non-high levels of FeNO were -0.8% and 0.1%, respectively (p < 0.01). In a multivariate analysis adjusted by age, body mass index, asthma control, blood eosinophil numbers, and FEV1% of predicted, a FeNO level of ≥40 ppb was independently associated with an accelerated decline in FEV1 (p < 0.05). CONCLUSIONS: This study suggests that FeNO is potentially valuable tool for identifying individuals who are at risk of a progressive loss of lung function among patients with controlled asthma.

Molecular properties and enhancement of thermostability by random mutagenesis of glutamate dehydrogenase from Bacillus subtilis.

The rocG gene encoding glutamate dehydrogenase from Bacillus subtilis (Bs-GluDH) was cloned, and expressed at considerable magnitude in Escherichia coli. The recombinant Bs-GluDH was purified to homogeneity and has been determined to have a hexameric structure (M(r) 270 kDa) with strict specificity for 2-oxoglutarate and L-glutamate, requiring NADH and NAD+ as cofactors respectively. The enzyme showed low thermostability with T(m) = 41 degrees C due to dissociation of the hexamer. To improve the thermostability of this enzyme, we performed error-prone PCR, introducing random mutagenesis on cloned GluDH. Two single mutant enzymes, Q144R and E27F, were isolated from the final mutant library. Their T(m) values were 61 degrees C and 49 degrees C respectively. Furthermore, Q144R had a remarkably high k(cat) value (435 s(-1)) for amination reaction at 37 degrees C, 1.3 times higher than that of the wild-type. Thus, Q144R can be used as a template gene to modify the substrate specificity of Bs-GluDH for industrial use.