Robust Output Feedback Control of Single-Link Flexible-Joint Robot Manipulator with Matched Disturbances Using High Gain Observer.

This article focuses on the output feedback control of single-link flexible-joint robot manipulators (SFJRMs) with matched disturbances and parametric uncertainties. Formally, four sensing elements are required to design the controller for single-link manipulators. We have designed a robust control technique for the semiglobal stabilization problem of the angular position of the link in the SFJRM system, with the availability of only a position sensing device. The sliding mode control (SMC) based output feedback controller is devised for SFJRM dynamics. The nonlinear model of SFJRM is considered to estimate the unknown states utilizing the high-gain observer (HGO). It is shown that the output under SMC using HGO-based estimated states coincides with that using original states when the gains of HGO are sufficiently high. Finally, the results are presented showing that the designed control technique works well when the SFJRM model is uncertain and matched perturbations are expected.

Identifying the heterogeneity of young adult rhinitis through cluster analysis in the Isle of Wight birth cohort.

BACKGROUND: Rhinitis affects many young adults and often shows comorbidity with asthma. OBJECTIVE: We hypothesized that young adult rhinitis, like asthma, exhibits clinical heterogeneity identifiable by means of cluster analysis. METHODS: Participants in the Isle of Wight birth cohort (n = 1456) were assessed at 1, 2, 4, 10, and 18 years of age. Cluster analysis was performed on those with rhinitis at age 18 years (n = 468) by using 13 variables defining clinical characteristics. RESULTS: Four clusters were identified. Patients in cluster 1 (n = 128 [27.4%]; ie, moderate childhood-onset rhinitis) had high atopy and eczema prevalence and high total IgE levels but low asthma prevalence. They showed the best lung function at 18 years of age, with normal fraction of exhaled nitric oxide (Feno), low bronchial hyperresponsiveness (BHR), and low bronchodilator reversibility (BDR) but high rhinitis symptoms and treatment. Patients in cluster 2 (n = 199 [42.5%]; ie, mild-adolescence-onset female rhinitis) had the lowest prevalence of comorbid atopy, asthma, and eczema. They had normal lung function and low BHR, BDR, Feno values, and total IgE levels plus low rhinitis symptoms, severity, and treatment. Patients in cluster 3 (n = 59 [12.6%]; ie, severe earliest-onset rhinitis with asthma) had the youngest rhinitis onset plus the highest comorbid asthma (of simultaneous onset) and atopy. They showed the most obstructed lung function with high BHR, BDR, and Feno values plus high rhinitis symptoms, severity, and treatment. Patient 4 in cluster 4 (n = 82 [17.5%]; ie, moderate childhood-onset male rhinitis with asthma) had high atopy, intermediate asthma, and low eczema. They had impaired lung function with high Feno values and total IgE levels but intermediate BHR and BDR. They had moderate rhinitis symptoms. CONCLUSION: Clinically distinctive adolescent rhinitis clusters are apparent with varying sex and asthma associations plus differing rhinitis severity and treatment needs.

Pathophysiological characterization of asthma transitions across adolescence.

BACKGROUND: Adolescence is a period of change, which coincides with disease remission in a significant proportion of subjects with childhood asthma. There is incomplete understanding of the changing characteristics underlying different adolescent asthma transitions. We undertook pathophysiological characterization of transitional adolescent asthma phenotypes in a longitudinal birth cohort. METHODS: The Isle of Wight Birth Cohort (N = 1456) was reviewed at 1, 2, 4, 10 and 18-years. Characterization included questionnaires, skin tests, spirometry, exhaled nitric oxide, bronchial challenge and (in a subset of 100 at 18-years) induced sputum. Asthma groups were "never asthma" (no asthma since birth), "persistent asthma" (asthma at age 10 and 18), "remission asthma" (asthma at age 10 but not at 18) and "adolescent-onset asthma" (asthma at age 18 but not at age 10). RESULTS: Participants whose asthma remitted during adolescence had lower bronchial reactivity (odds ratio (OR) 0.30; CI 0.10 -0.90; p = 0.03) at age 10 plus greater improvement in lung function (forced expiratory flow 25-75% gain: 1.7 L; 1.0-2.9; p = 0.04) compared to persistent asthma by age 18. Male sex (0.3; 0.1-0.7; p < 0.01) and lower acetaminophen use (0.4; 0.2-0.8; p < 0.01) independently favoured asthma remission, when compared to persistent asthma. Asthma remission had a lower total sputum cell count compared to never asthma (31.5 [25-75 centiles] 12.9-40.4) vs. 47.0 (19.5-181.3); p = 0.03). Sputum examination in adolescent-onset asthma showed eosinophilic airway inflammation (3.0%, 0.7-6.6), not seen in persistent asthma (1.0%, 0-3.9), while remission group had the lowest sputum eosinophil count (0.3%, 0-1.4) and lowest eosinophils/neutrophils ratio of 0.0 (Interquartile range: 0.1). CONCLUSION: Asthma remission during adolescence is associated with lower initial BHR and greater gain in small airways function, while adolescent-onset asthma is primarily eosinophilic.

The effect of parental allergy on childhood allergic diseases depends on the sex of the child.

BACKGROUND: The parent-of-origin effect is important in understanding the genetic basis of childhood allergic diseases and improving our ability to identify high-risk children. OBJECTIVE: We sought to investigate the parent-of-origin effect in childhood allergic diseases. METHODS: The Isle of Wight Birth Cohort (n= 1456) has been examined at 1, 2, 4, 10, and 18 years of age. Information on the prevalence of asthma, eczema, rhinitis, and environmental factors was obtained by using validated questionnaires. Skin prick tests were carried out at ages 4, 10, and 18 years, and total IgE measurement was carried out at 10 and 18 years. Parental history of allergic disease was assessed soon after the birth of the child, when maternal IgE levels were also measured. Prevalence ratios (PRs) and their 95% CIs were estimated, applying log-linear models adjusted for confounding variables. RESULTS: When stratified for sex of the child, maternal asthma was associated with asthma in girls (PR, 1.91; 95% CI, 1.34-2.72; P= .0003) but not in boys (PR, 1.29; 95% CI, 0.85-1.96; P= .23), whereas paternal asthma was associated with asthma in boys (PR, 1.99; 95% CI, 1.42-2.79; P< .0001) but not in girls (PR, 1.03; 95% CI, 0.59-1.80; P= .92). Maternal eczema increased the risk of eczema in girls (PR, 1.92; 95% CI, 1.37-2.68; P= .0001) only, whereas paternal eczema did the same for boys (PR, 2.07; 95% CI, 1.32-3.25; P = .002). Similar trends were observed when the effect of maternal and paternal allergic disease was assessed for childhood atopy and when maternal total IgE levels were related to total IgE levels in children at ages 10 and 18 years. CONCLUSIONS: The current study indicates a sex-dependent association of parental allergic conditions with childhood allergies, with maternal allergy increasing the risk in girls and paternal allergy increasing the risk in boys. This has implications for childhood allergy prediction and prevention.

What does adolescent undiagnosed wheeze represent? Findings from the Isle of Wight Cohort.

We sought to characterise adolescent wheeze in the absence of asthma, which we termed "undiagnosed wheeze". The Isle of Wight Birth Cohort (n=1,456) was reviewed at 1, 2, 4, 10 and 18 yrs. Using questionnaire responses, "asthma" was defined as "ever had asthma" plus either "wheezing in the last 12 months" or "taking asthma treatment in the last 12 months"; "undiagnosed wheeze" as "wheeze in the last 12 months" but "no" to "ever had asthma"; and remaining subjects termed "non-wheezers". Undiagnosed wheeze (prevalence 4.9%) accounted for 22% of wheezing at 18 yrs. This was largely adolescent-onset with similar symptom frequency and severity to diagnosed asthma. However, undiagnosed wheezers had significantly higher forced expiratory volume in 1 s to forced vital capacity ratio, less bronchodilator reversibility and bronchial hyperresponsiveness, and were less frequently atopic than asthmatics. Undiagnosed wheezers had earlier smoking onset, higher smoking rates and monthly paracetamol use than non-wheezers. Logistic regression identified paracetamol use (OR 1.11, 95% CI 1.01-1.23; p=0.03), smoking at 18 yrs (OR 2.54, 95% CI 1.19-5.41; p=0.02), rhinitis at 18 yrs (OR 2.82, 95% CI 1.38-5.73; p=0.004) and asthmatic family history (OR 2.26, 95% CI 1.10-4.63; p=0.03) as significant independent risk factors for undiagnosed wheeze. Undiagnosed wheeze is relatively common during adolescence, differs from diagnosed asthma and has strong associations with smoking and paracetamol use. Better recognition of undiagnosed wheeze and assessment of potential relevance to adult health is warranted.

Effect of inhaled budesonide/formoterol fumarate dihydrate delivered via two different devices on lung function in patients with COPD and low peak inspiratory flow.

BACKGROUND AND AIMS: Low peak inspiratory flow (PIF) is common following severe exacerbations of chronic obstructive pulmonary disease (COPD). Patients with COPD and low PIF may be at risk of suboptimal delivery of inhaled therapies to the airways, especially when using devices such as dry powder inhalers (DPIs), which require greater inspiratory effort than metered dose inhalers (MDIs). We report the results from a 2-week crossover study evaluating the effects of inhaled dual therapy with budesonide/formoterol fumarate dihydrate with an MDI with a spacer versus a DPI in patients with COPD and low PIF. METHODS: This randomized, open-label, two-period (each 1 week in duration) crossover efficacy and safety study included patients with severe-to-very severe COPD and PIF < 50 L/min (NCT04078126). Patients were randomized 1:1 to twice-daily budesonide/formoterol fumarate dihydrate MDI (BFF MDI) 320/10 µg with a spacer for 1 week followed by twice-daily budesonide/formoterol fumarate dihydrate DPI (BUD/FORM DPI) 320/9 µg for 1 week, or the inverse. The primary endpoint was peak change from baseline in forced expiratory volume in 1 s (FEV1) within 4 h post-dose following 1 week of treatment. Other assessments included pre-dose lung function, pharmacokinetics, and safety, as assessed by adverse events. RESULTS: The modified intention-to-treat analysis set comprised 30 patients (mean age: 66.9 years; mean baseline FEV1: 766 mL; mean COPD assessment test score: 22.20). Following 1 week of treatment, both BFF MDI and BUD/FORM DPI improved mean [95% confidence interval (CI)] peak FEV1 4 h post-dose [256 (190, 322) mL and 274 (208, 340) mL, respectively]. No clinically meaningful difference between treatments was observed for any lung function endpoint. There were no unexpected safety findings. CONCLUSION: Dual therapy with BFF MDI and with BUD/FORM DPI led to improvements in lung function in patients with severe-to-very severe COPD and low PIF.

Influence of atopy and asthma on exhaled nitric oxide in an unselected birth cohort study.

BACKGROUND: Asthma is considered to be associated with elevated levels of exhaled nitric oxide (FeNO). The nature of this relationship and how it is influenced by atopy are still not resolved. METHODS: The Isle of Wight birth cohort (N=1456) was reassessed at 18 years of age. Participants able to attend the research centre were assessed by questionnaires, skin prick testing and FeNO in order to explore the interrelationship between asthma, atopy and FeNO. RESULTS: Atopy was significantly associated with higher levels of FeNO. However, the level of FeNO for non-atopic asthmatic participants was no different to the non-atopic no-asthma group. The highest levels of FeNO were seen in subjects with both atopy and asthma. In addition, FeNO was positively associated with increasing atopic burden as evidenced by increasing FeNO with increasing skin prick testing positivity, and with increasing severity of atopic asthma as evidenced by the number of attacks of wheezing. FeNO and current inhaled corticosteroid use were not significantly associated. CONCLUSIONS: FeNO behaves as a biomarker of atopy and the "allergic asthma" phenotype rather than asthma itself. This may explain why FeNO-guided asthma treatment outcomes have proved to be of limited success where atopic status has not been considered and accounted for.

Are exhaled nitric oxide measurements using the portable NIOX MINO repeatable?

BACKGROUND: Exhaled nitric oxide is a non-invasive marker of airway inflammation and a portable analyser, the NIOX MINO (Aerocrine AB, Solna, Sweden), is now available. This study aimed to assess the reproducibility of the NIOX MINO measurements across age, sex and lung function for both absolute and categorical exhaled nitric oxide values in two distinct groups of children and teenagers. METHODS: Paired exhaled nitric oxide readings were obtained from 494 teenagers, aged 16-18 years, enrolled in an unselected birth cohort and 65 young people, aged 6-17 years, with asthma enrolled in an interventional asthma management study. RESULTS: The birth cohort participants showed a high degree of variability between first and second exhaled nitric oxide readings (mean intra-participant difference 1.37 ppb, 95% limits of agreement -7.61 to 10.34 ppb), although there was very close agreement when values were categorised as low, normal, intermediate or high (kappa = 0.907, p < 0.001). Similar findings were seen in subgroup analyses by sex, lung function and asthma status. Similar findings were seen in the interventional study participants. CONCLUSIONS: The reproducibility of exhaled nitric oxide is poor for absolute values but acceptable when values are categorised as low, normal, intermediate or high in children and teenagers. One measurement is therefore sufficient when using categorical exhaled nitric oxide values to direct asthma management but a mean of at least two measurements is required for absolute values.

Characterisation of asthma that develops during adolescence; findings from the Isle of Wight Birth Cohort.

BACKGROUND: Understanding of adolescent-onset asthma remains limited. We sought to characterise this state and identify associated factors within a longitudinal birth cohort study. METHODS: The Isle of Wight Whole Population Birth Cohort was recruited in 1989 (N=1456) and characterised at 1, 2, 4, 10 and 18-years. "Adolescent-onset asthma" was defined as asthma at age 18 without prior history of asthma, "persistent-adolescent asthma" as asthma at both 10 and 18 and "never-asthma" as those without asthma at any assessment. RESULTS: Adolescent-onset asthma accounted for 28.3% of asthma at 18-years and was of similar severity to persistent-adolescent asthma. Adolescent-onset asthmatics showed elevated bronchial hyper-responsiveness (BHR) and atopy at 10 and 18 years. BHR in this group at 10 was intermediate to that of never-asthmatics and persistent-adolescent asthma. By 18 their BHR, bronchodilator reversibility and sputum eosinophilia was greater than never-asthmatics and comparable to persistent-adolescent asthma. At 10, males who later developed adolescent-onset asthma had reduced FEV(1) and FEF(25-75), while females had normal lung function but then developed impaired FEV(1) and FEF(25-75) in parallel with adolescent asthma. Factors independently associated with adolescent-onset asthma included atopy at 10 (OR=2.35; 95% CI=1.08-5.09), BHR at 10 (3.42; 1.55-7.59), rhinitis at 10 (2.35; 1.11-5.01) and paracetamol use at 18-years (1.10; 1.01-1.19). CONCLUSIONS: Adolescent-onset asthma is associated with significant morbidity. Predisposing factors are atopy, rhinitis and BHR at age 10 while adolescent paracetamol use is also associated with this state. Awareness of potentially modifiable influences may offer avenues for mitigating this disease state.