Circadian variability in airways characteristics: A spirometric study

Circadian rhythm and variability of large and small airway spirometric variables in healthy individuals

Objective

To assess the diurnal rhythm and variability of lung function in healthy individuals, encompassing both large and small airways.

Methods

A prospective study enrolled 35 healthy adults without a history of smoking. Initial spirometry and a bronchodilation test were performed using the Jaeger spirometer, followed by a seven-day continuous home monitoring using the GOSPT2000. We evaluated repeatability using the intraclass correlation coefficient and agreement through linear regression and Bland-Altman analyses. Circadian rhythm and variability in spirometric measurements were analyzed using the coefficient of variation (CV) and daily variation rate.

Results

The GOSPT2000 demonstrated strong repeatability and high agreement with the Jaeger spirometer. Notable findings included a decrease in nocturnal forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV3 by 44, 59, and 53 mL, respectively. In contrast, peak expiratory flow at noon showed an increase of 0.143L/min. Small-airway variables, including forced expiratory flow at 50% and 75% of the FVC and maximum midexpiratory flow, showed no significant diurnal variation. The nocturnal CV for large-airway variables was ≤ 4%, while for small-airway variables, it was ≤ 11.89%.

Conclusion

This study has established a spectrum of variability for both large and small airways in healthy populations. The variability of small-airway variables is higher than that of large-airway variables. The investigation into the diurnal rhythms and variability characteristics of both large and small airway variables in the healthy population can serve as a foundation for diagnosing asthma or assessing the efficacy of asthma treatments.

Effects of repetition as training and incentives on the performance in pulmonary function tests in healthy volunteers

Pulmonary function testing (PFT) is a central part of diagnosis and treatment monitoring in respiratory medicine. Few studies have investigated whether repeated PFT or training can significantly influence performance. To investigate potential training effects of repeated PFT, 30 healthy volunteers underwent daily and weekly repeated PFT with spirometry over 10 weeks. The study included 22 females and 8 males with a mean age of 31.8 years ± 15 (SD), a mean weight of 66.3 kg ± 14.5 (SD) and a mean BMI of 22.4 ± 3.3 (SD). The first 5 PFTs were performed on 5 consecutive days, followed by 3 PFTs once a week on the same day of the week. Subsequently, 5 measurements were taken daily for 5 consecutive days. After these 13 appointments in 5 weeks, participants were randomly assigned to the control or incentive group, with stratification for age and gender. The incentive group had the opportunity to win money (200 €) for the highest increase in forced vital capacity (FVC). PFTs were performed once a week on the same day of the week as before for 5 more times. Motivation was assessed by a questionnaire before the 1st, 9th and 18th measure of PFT at three time points throughout the study. An increase in PFT was observed with mean increases of 473 [ml] in FVC, 395 [ml] in forced expiratory volume in 1 s (FEV1) and 1.382 [litres/second] in peak expiratory flow (PEF) after four days of daily PFT. These increases did not persist and spirometric data returned to baseline after one week. After allocation, participants in the incentive group did not increase their FVC, FEV1 or PEF compared to the control group. The incentive group showed higher motivation than the control group, even before allocation. Repeated daily PFT could induce short-term increases, but PFT does not fluctuate significantly in the long term. External influences that affect motivation could not consistently increase PFT. For clinical practice, it can be concluded that PFT does not necessarily require extended training to ensure reliability if reproducibility criteria are met.

Association of rest-activity circadian rhythm with chronic respiratory diseases, a cross-section survey from NHANES 2011-2014

OBJECTIVE

A growing number of studies have examined the 24-h rest-activity characteristics in relation to health outcomes. Up to now, few studies have paid attention to the role of rest-activity circadian rhythm in chronic respiratory diseases (CRDs); therefore, to fill this gap, our study innovatively explored the association of rest-activity circadian rhythm indices with CRDs.

METHODS

A total of 7412 participants from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were included in this study. The rest-activity circadian rhythm indices were calculated using accelerometer data and were divided into quartiles to perform logistic regression.

RESULTS

Participants in the highest quartile of Relative amplitude (RA) had a lower prevalence of emphysema, chronic bronchitis and asthma, compared to those in the lowest quartile. Participants in the highest quartile of Intradaily variability (IV) was associated with a higher prevalence of emphysema relative to those in the lowest quartile. Compared to those in the lowest quartile, participants in the highest quartile of the average activity of the most active continuous 10-h period (M10) had a lower prevalence of emphysema. Additionally, compared to those in the lowest quartile of the average activity of the least active continuous 5-h period (L5) and L5 start time, participants in the highest quartile had a higher prevalence of asthma.

CONCLUSIONS

This study demonstrated that in general US adult population, disrupted rest-activity circadian rhythm was associated with a higher prevalence of CRDs.

Short-term exposure to zinc- and copper-containing welding fumes: Effects on pulmonary function in humans

Zinc- and copper-containing welding fumes typically induce a systemic inflammation indicated by increase in C-reactive protein (CRP) levels, also known as welding fume fever. It typically includes symptoms like fever, myalgia or headaches, but only a quarter of patients experience respiratory symptoms, e.g. coughing. This retrospective analysis of data of three studies with either control (filtered air) or zinc- and copper-containing welding fume exposure aims to identify and characterize the effect of the welding fumes on lung function. Spirometry and body plethysmography data of male healthy volunteers were analyzed and comparisons between different timepoints after a 6 h exposure were conducted. For controls no significant changes in spirometry were observed between baseline and 6 h, 24 h and 1 week after exposure. For volunteers exposed to zinc- and copper-containing welding fumes no significant reductions in forced expiratory volume in 1 s (FEV1) and minimal reductions in vital capacity (VC) (52 ml, 0.9%) were detected after 6 h. After 24 h significant reductions in FEV1 (147 ml, 3.2%) and VC (162 ml, 2.9%) could be observed. 1 week after exposure FEV1 was still significantly reduced (102 ml, 2.1%) and airway resistance were increased while no differences in VC were detected. The reduction of FEV1% after 24 week significantly correlated with increases in CRP levels. In conclusion, a single exposure to zinc- and copper-containing welding fumes leads not only to a systemic inflammation but could also induce slight sustained airway constrictions after 24 h and 1 week. The observed slight airway constriction is not caused by immediate effects but possibly inflammatory processes. Although welding fume fever does not necessarily present respiratory symptoms, welders exposed to zinc- and copper-containing welding fumes should be monitored for respiratory symptoms and obstructive ventilation pattern.

Mental health indices may fully mediate the relationship between morningness-eveningness and disease control among adult asthma patients

Objective: The aim of this study was to assess the association between morningness-eveningness and disease control with consideration of mental state as a mediator and the control of confounding factors among adult asthma patients.Methods: This is a cross-sectional study, which included a nonrandom sample of N = 66 patients from an outpatient unit with a confirmed asthma diagnosis, who gave an informed consent and completed a set of questionnaires: a survey comprising questions about sociodemographic and clinical characteristics, the Asthma Control Test (ACT), the Composite Scale of Morningness (CSM), and the General Health Questionnaire (GHQ-28). Mediation models were created separately for each GHQ-28 dimension (somatic symptoms, anxiety/insomnia, social dysfunction and depressive symptoms), for a total score and for four GHQ-28 dimensions together, considered as mediators.Results: Low morning affect was related to poor disease symptom control among patients with asthma. The effect was fully mediated by non-psychotic mental health indices. Evening-time preference was associated with a rise in asthma control, and mediated by somatic symptoms and anxiety/insomnia, when controlled for morning affect.Conclusions: The current study underlines the significance of assessment of both individual morningness-eveningness preference and mental health in the management of asthma symptoms.

Asthma diagnosis: into the fourth dimension

Asthma is the most common chronic respiratory disease in the UK; however, the misdiagnosis rate is substantial. The lack of consistency in national guidelines and the paucity of data on the performance of diagnostic algorithms compound the challenges in asthma diagnosis. Asthma is a highly rhythmic disease, characterised by diurnal variability in clinical symptoms and pathogenesis. Asthma also varies day to day, seasonally and from year to year. As much as it is a hallmark for asthma, this variability also poses significant challenges to asthma diagnosis. Almost all established asthma diagnostic tools demonstrate diurnal variation, yet few are performed with standardised timing of measurements. The dichotomous interpretation of diagnostic outcomes using fixed cut-off values may further limit the accuracy of the tests, particularly when diurnal variability straddles cut-off values within a day, and careful interpretation beyond the 'positive' and 'negative' outcome is needed. The day-to-day and more long-term variations are less predictable and it is unclear whether performing asthma diagnostic tests during asymptomatic periods may influence diagnostic sensitivities. With the evolution of asthma diagnostic tools, home monitoring and digital apps, novel strategies are needed to bridge these gaps in knowledge, and circadian variability should be considered during the standardisation process. This review summarises the biological mechanisms of circadian rhythms in asthma and highlights novel data on the significance of time (the fourth dimension) in asthma diagnosis.

Circadian Variations in Cellular Composition of Lymphoid Organs in Rats with Experimental Endomyometritis

Circadian variations in the cellular composition of the lymphoid organs were studied in female Wistar rats under normal conditions and in experimental endomyometritis. The fractions of CD8⁺ cells (effector killers), CD25⁺ cells (activated/immature lymphocytes), as well as large, medium, small lymphocytes and monocytes/macrophages were assessed at 10.00 and 20.00 h. In the thymus and spleen of rats with endomyometritis, the number of parameters demonstrating significant circadian variations was lower than in intact animals. In the lymph nodes, morning/evening differences appeared for the number of CD8⁺ and CD25⁺ cells and monocytes/macrophages in the para-aortic lymph nodes, the number of large and small lymphocytes and CD8⁺ cells in inguinal lymph nodes, and in the number of large lymphocytes, CD8⁺ cells, and monocytes/macrophages in the ileal lymph nodes. Thus, the development of chronic inflammation in the uterine and vaginal mucosa was accompanied by desynchronosis in the immune system. Hence, circadian rhythms should be taken into consideration in the diagnosis and treatment of the disease.

A compendium answering 150 questions on COVID-19 and SARS-CoV-2

In December 2019, China reported the first cases of the coronavirus disease 2019 (COVID‐19). This disease, caused by the severe acute respiratory syndrome–related coronavirus 2 (SARS‐CoV‐2), has developed into a pandemic. To date, it has resulted in ~9 million confirmed cases and caused almost 500 000 related deaths worldwide. Unequivocally, the COVID‐19 pandemic is the gravest health and socioeconomic crisis of our time. In this context, numerous questions have emerged in demand of basic scientific information and evidence‐based medical advice on SARS‐CoV‐2 and COVID‐19. Although the majority of the patients show a very mild, self‐limiting viral respiratory disease, many clinical manifestations in severe patients are unique to COVID‐19, such as severe lymphopenia and eosinopenia, extensive pneumonia, a “cytokine storm” leading to acute respiratory distress syndrome, endothelitis, thromboembolic complications, and multiorgan failure. The epidemiologic features of COVID‐19 are distinctive and have changed throughout the pandemic. Vaccine and drug development studies and clinical trials are rapidly growing at an unprecedented speed. However, basic and clinical research on COVID‐19–related topics should be based on more coordinated high‐quality studies. This paper answers pressing questions, formulated by young clinicians and scientists, on SARS‐CoV‐2, COVID‐19, and allergy, focusing on the following topics: virology, immunology, diagnosis, management of patients with allergic disease and asthma, treatment, clinical trials, drug discovery, vaccine development, and epidemiology. A total of 150 questions were answered by experts in the field providing a comprehensive and practical overview of COVID‐19 and allergic disease.

Association analysis between chronic obstructive pulmonary disease and polymorphisms in circadian genes

Background

Circadian genes have been suggested to play an important role in lung pathology. However, it remains unknown whether polymorphisms of these genes are associated with chronic obstructive pulmonary disease (COPD). Here, we aimed to investigate the association of circadian genes polymorphisms with COPD in a case-control study of 477 COPD patient and 323 control Han Chinese persons.

Methods

Genotyping assays were carried out for nine single nucleotide polymorphisms (SNPs) from five circadian genes (PER3, CLOCK, RORB, BMAL1 and CRY2) that were previously identified in lung pathology. Age, sex, BMI and smoking status and comorbidities were recorded for all subjects.

Results

No significant association was found in all SNP sites in overall subjects and no significant difference was found in age, sex, smoking status stratification analysis.

Discussion

The findings of this investigation indicated the effect of circadian genes polymorphisms on COPD susceptibility may only be small and possibly dependent on the subject factors, such as age and sex.

Reduced Cross-Shift Lung Function and Respiratory Symptoms among Integrated Textile Factory Workers in Ethiopia

Chronic respiratory symptoms and reduction in lung function has been described as a common health problem among textile workers in low- and middle-income countries. The objective of this study was to measure lung function and respiratory symptoms among workers from an integrated textile factory. A comparative cross-sectional study design with a cross-shift lung function measurement was performed in 306 cotton dust exposed workers from an integrated textile factory and 156 control workers from a water bottling factory. An integrated textile factory typically has four main production departments (spinning, weaving, finishing, and garment) that process raw cotton and manufacture clothes or fabrics. Respiratory symptoms were assessed by adopting the standard American Thoracic Society questionnaire. Descriptive statistics and logistic and linear regression analysis were used. The prevalence of respiratory symptoms was significantly higher among textile workers (54%) than in controls (28%). Chronic cough, chest tightness, and breathlessness were significantly higher among textile workers (23%, 33%, and 37%, respectively) than in the control group (5%, 17% and 6%, respectively). Breathlessness was the most prevalent chronic respiratory symptom with highest adjusted odds ratio 9.4 (95% CI 4.4–20.3). A significantly higher cross-shift lung function reduction was observed among textile workers (123 mL for FEV₁ and 129 mL for FVC) compared with the control group (14 mL for FEV₁ and 12 mL for FVC). Thus, workers’ respiratory health protection programs should be strengthened in textile factories.

Circadian rhythm of airways caliber and its autonomic modulation

The autonomic nervous system (ANS) is one of the effector pathways for circadian variation of many physiological parameters. Autonomic tone and airways caliber have been reported to exhibit circadian variation in separate studies. A simultaneous investigation of heart rate variability (HRV) and airway caliber might ascertain how airway caliber is modulated by autonomic tone. This study was planned to identify the variations in airway caliber and autonomic function tone during a 24-hour span. A total of 56 healthy male subjects with almost similar daily routines were studied. Time domain, frequency domain and nonlinear analysis of R-R interval from 5 min electrocardiogram (ECG) was done seven times during the daytime wake span at 3-hour intervals starting at 05:00 h in the morning until 23:00 h in the night. Simultaneously peak expiratory flow rate (PEFR) was determined using a mini Wright's peak flow meter. Rhythmometric analysis was done for PEFR and HRV parameters. Significant circadian variation in low frequency (LF) and high frequency (HF) variance was identified in this group of healthy subjects. The circadian rhythm of LF variance was characterized by a gradual increase and corresponding reciprocal change in HF variance from morning until night. The LF/HF ratio and SD2/SD1 ratio reflecting sympatho-vagal balance showed low to high values from morning to evening. The acrophase of the PEFR temporal pattern is similar to that of LF power and almost opposite in phase to that of HF power. PEFR is positively correlated with LF power. The circadian rhythm of airway caliber co-varies with cardiac autonomic tone. It appears that the temporal pattern of cardiac autonomic tone precedes in time that of airways caliber, thereby suggesting the latter operates under the modulatory effect of the 24-hour pattern in sympatho-vagal balance.