The latest medical research on Sleep Medicine

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about sleep medicine gathered by our medical AI research bot.

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Silica-associated lung disease: An old-world exposure in modern industries.


Despite silica dust exposure being one of the earliest recognized causes of lung disease, Australia, USA, Israel, Turkey and other countries around...

Alternaria induces airway epithelial cytokine expression independent of protease-activated receptor.


A novel fungal allergen, Alternaria (Alt), has been previously shown to associate with the pathogenesis of allergic rhinitis and bronchial asthma, particularly in arid and semi-arid regions. Airway epithelial cells are among the first to encounter Alt, and epithelial cytokine production and subsequent airway inflammation are early events in the response to Alt exposure. However, the underlying mechanism is unclear. As protease-activated receptor 2 (PAR2) has been implicated in most of the Alt-induced biological events, we investigated the regulation of airway inflammation and epithelial cytokine expression by PAR2.

Wild-type (WT) and Par2 knockout (Par2-KO) mice were used to evaluate the in vivo role of PAR2. Primary human and mouse airway epithelial cells were used to examine the mechanistic basis of epithelial cytokine regulation in vitro.

Surprisingly, Par2 deficiency had no negative impact on the change of lung function, inflammation and cytokine production in the mouse model of Alt-induced asthma. Alt-induced cytokine production in murine airway epithelial cells from Par2-KO mice was not significantly different from the WT cells. Consistently, PAR2 knockdown in human cells also had no effect on cytokine expression. In contrast, the cytokine expressions induced by synthetic PAR2 agonist or other asthma-related allergens (e.g. cockroach extracts) were indeed mediated via a PAR2-dependent mechanism. Finally, we found that EGFR pathway was responsible for Alt-induced epithelial cytokine expression.

The activation of EGFR, but not PAR2, was likely to drive the airway inflammation and epithelial cytokine production induced by Alt.

Inter-observer variation in image interpretation and the prognostic importance of non-expansile lung in malignant pleural effusion.


Non-expansile lung (NEL) frequently complicates management of malignant pleural effusion (MPE) and is an important factor in clinical practice and trials. NEL is frequently diagnosed on a single radiographic observation, but neither the inter-observer agreement of this approach nor the prognostic importance of NEL in MPE has been reported.

A multicentre retrospective cohort study was performed in two UK pleural centres. NEL was defined as <50% pleural re-apposition on post-drainage radiographs by primary and secondary assessors at each site. Inter-observer agreement was assessed by Cohen's kappa (κ). Kaplan-Meier methodology and multivariate Cox models were used to assess the prognostic impact of NEL versus no NEL and 'complete NEL' versus 'complete expansion', based on a single assessor's results from each site.

NEL was identified by the primary assessor in 33 of 97 (34%) in Cohort 1 and 15 of 86 (17%) in Cohort 2. Inter-observer agreement between assessors was only fair-to-moderate (Cohort 1 κ: 0.38 (95% CI: 0.21-0.55), Cohort 2 κ: 0.51 (95% CI: 0.30-0.72)). In both cohorts, NEL was associated with shorter median overall survival (Cohort 1: 188 vs 371 days, Cohort 2: 192 vs 412 days). This prognostic association was independent in Cohort 1 (hazard ratio (HR): 2.19, 95% CI: 1.31-3.66) but not in Cohort 2 (HR: 1.42, 95% CI: 0.71-2.87). Survival was inferior in both cohorts in cases of complete NEL versus complete expansion.

Radiographic NEL is common but inter-observer agreement is only fair-to-moderate. NEL is associated with adverse survival. These data do not support the use of single radiographic assessments to classify NEL.

Assessing ventilatory control stability in children with and without an elevated central apnoea index.


Frequent central apnoeas are sometimes observed in healthy children; however; the pathophysiology of an elevated central apnoea index (CAI) is poorly understood. A raised CAI may indicate underlying ventilatory control instability (i.e. elevated loop gain, LG) or a depressed ventilatory drive. This pilot study aimed to compare LG in otherwise healthy children with an elevated CAI to healthy controls.

Polysomnographic recordings from children (age > 6 months) without obstructive sleep apnoea and with a CAI > 5 events/h (n = 13) were compared with age and gender-matched controls with a CAI < 5 events/h (n = 13). Spontaneous sighs were identified during non-rapid eye movement (NREM) sleep, and breath-breath measurements of ventilation were derived from the nasal pressure signal. A standard model of ventilatory control (gain, time constant and delay) was used to calculate LG by transforming ventilatory fluctuations seen in response to a sigh into a ventilatory-drive signal that best matches observed ventilation.

The high CAI group had an elevated LG (median = 0.36 (interquartile range, IQR = 0.35-0.53) vs 0.28 (0.23-0.36); P ≤ 0.01). There was no difference in either the time constant (P = 0.63) or delay (P = 0.29) between groups. Elevated LG observed in the high CAI group remained after accounting for degree of hypoxia (average oxygen saturation (SpO2 ) during each analysable window) experienced (0.40 (0.30-0.53) vs 0.25 (0.23-0.37); P = 0.04).

An elevated CAI in otherwise healthy children is associated with a raised LG compared to matched controls with a low CAI, irrespective of level of hypoxia. This relative ventilatory instability helps explain the high CAI and may ultimately be able to help guide diagnosis and management in patients with high CAI.

Challenges to and opportunities for the implementation of non-invasive positive pressure ventilation in the Asia-Pacific region.


Non-invasive positive pressure ventilation (NPPV) is undoubtedly one of the most significant advancements in mechanical ventilation technology in t...

Effects of sleep restriction on metabolism-related parameters in healthy adults: A comprehensive review and meta-analysis of randomized controlled trials.

Sleep Medicine Reviews

This review aimed to provide a comprehensive examination of the effect of sleep restriction on metabolism-related parameters by synthesizing the em...

Pulmonary artery enlargement predicts poor outcome during acute exacerbations of fibrotic interstitial lung disease.


In fibrotic interstitial lung disease (f-ILD), pulmonary artery diameter to ascending aorta diameter ratio (PA/A) ≥ 1 during the stable stage is associated with worse outcomes; however, the effect of acute exacerbation (AE) on the PA/A is unknown.

Patients with a diagnosis of AE of f-ILD and with a computed tomography (CT) scan performed during stable period to confirm background fibrosis, as well as a CT scan at admission, were included. The pulmonary arterial diameter, ascending aortic diameter and PA/A were measured using CT during AE and CT prior to AE, when available, to evaluate the changes. Demographic data, co-morbidities and clinical outcome (90-day mortality) were analysed.

Of the 123 patients included, 45 had a PA/A ≥ 1 during AE and compared to the PA/A < 1 group, they were younger, had lower % vital capacity (VC) and % forced vital capacity (FVC), required more long-term oxygen therapy and other treatments, and had lower PaO2 /FiO2 (P/F) ratios. During AE, the PA/A increased from that during stable periods (P < 0.001), and a PA/A ≥ 1 was significantly associated with 90-day mortality both before and after adjustment for age, the P/F ratio at admission, long-term oxygen therapy usage and the type of background f-ILD (P = 0.018 and 0.025).

To the best of our knowledge, this is the first longitudinal examination of the PA/A ratio and evaluation during AE of f-ILD. Our data show that a PA/A ≥ 1 during AE predicted poor survival outcome in f-ILD.

The past, present and future of pulmonary rehabilitation.


Abundant evidence supports the use of pulmonary rehabilitation as a treatment for stable and exacerbated chronic obstructive pulmonary disease. Sev...

Biphasic changes in airway epithelial cell EGF receptor binding and phosphorylation induced by components of hogbarn dust.

Exp Lung Res

Workers in enclosed hogbarns experience an increased incidence of airway inflammation and obstructive lung disease, and an aqueous hogbarn dust extract (HDE) induces multiple inflammation-related responses in cultured airway epithelial cells. Epidermal growth factor receptor (EGFR) phosphorylation and activation has been identified as one important mediator of inflammatory cytokine release from these cells. The studies here investigated both early and late phase adaptive changes in EGFR binding properties and subcellular localization induced by exposure of cells to HDE.

Cell surface EGFRs were quantified as binding to intact cells on ice. EGFR phosphorylation, expression, and localization were assessed with anti-EGFR antibodies and either blotting or confocal microscopy.

In BEAS-2B and primary human bronchial epithelial cells, HDE induced decreases in cell surface EGFR binding following both 15-min and 18-h exposures. In contrast, H292 cells exhibited only the 15-min decrease, with binding near the control level at 18 hr. Confocal microscopy showed that the 15-min decrease in binding is due to EGFR endocytosis. Although total EGFR immunoreactivity decreased markedly at 18 hr in confocal microscopy with BEAS-2B cells, immunoblots showed no loss of EGFR protein. HDE stimulated EGFR phosphorylation at both 15 min and 18 hr in BEAS-2B cells and primary cells, but only at 15 min in H292 cells, indicating that the different EGFR binding changes among these cell types is likely related to their different time-dependent changes in phosphorylation.

These studies extend the evidence for EGFRs as important cellular targets for components of HDE and they reveal novel patterns of EGFR phosphorylation and binding changes that vary among airway epithelial cell types. The results provide both impetus and convenient assays for identifying the EGFR-activating components and pathways that likely contribute to hogbarn dust-induced lung disease in agricultural workers.

Worldwide and regional prevalence rates of co-occurrence of insomnia and insomnia symptoms with obstructive sleep apnea: A systematic review and meta-analysis.

Sleep Medicine Reviews

Recent investigations have established that patients with obstructive sleep apnea (OSA) and insomnia have greater daytime impairments and reduced q...

Quantitative assessment of airway remodelling and response to allergen in asthma.


In vivo evaluation of the microstructural differences between asthmatic and non-asthmatic airways and their functional consequences is relevant to understanding and, potentially, treating asthma. In this study, we use endobronchial optical coherence tomography to investigate how allergic airways with asthma differ from allergic non-asthmatic airways in baseline microstructure and in response to allergen challenge.

A total of 45 subjects completed the study, including 20 allergic, mildly asthmatic individuals, 22 non-asthmatic allergic controls and 3 healthy controls. A 3-cm airway segment in the right middle and right upper lobe were imaged in each subject immediately before and 24 h following segmental allergen challenge to the right middle lobe. Relationships between optical airway measurements (epithelial and mucosal thicknesses, mucosal buckling and mucus) and airway obstruction (FEV1 /FVC (forced expiratory volume in 1 s/forced vital capacity) and FEV1 % (FEV1 as a percentage of predictive value)) were investigated.

Significant increases at baseline and in response to allergen were observed for all four of our imaging metrics in the asthmatic airways compared to the non-asthmatic airways. Epithelial thickness and mucosal buckling exhibited a significant relationship to FEV1 /FVC in the asthmatic group.

Simultaneous assessments of airway microstructure, buckling and mucus revealed both structural and functional differences between the mildly asthmatic and control groups, with airway buckling seeming to be the most relevant factor. The results of this study demonstrate that a comprehensive, microstructural approach to assessing the airways may be important in future asthma studies as well as in the monitoring and treatment of asthma.

Changes in physical activity during hospital admission for chronic respiratory disease.


Establishing the amount of inpatient physical activity (PA) undertaken by individuals hospitalized for chronic respiratory disease is needed to inform interventions. This observational study investigated whether PA changes when a person is an inpatient, how long is required to obtain representative PA measures and whether PA varies within a day and between patients of differing lengths of stay.

A total of 389 participants were recruited as early as possible into their hospitalization. Patients wore a PA monitor from recruitment until discharge. Step count was extracted for a range of wear time criteria. Single-day intraclass correlation coefficients (ICC) were calculated, with an ICC ≥ 0.80 deemed acceptable.

PA data were available for 259 participants. No changes in daily step count were observed during the inpatient stay (586 (95% CI: 427-744) vs 652 (95% CI: 493-812) steps/day for day 2 and 7, respectively). ICC across all wear time criteria were > 0.80. The most stringent wear time criterion, retaining 80% of the sample, was ≥11 h on ≥1 day. More steps were taken during the morning and afternoon than overnight and evening. After controlling for the Medical Research Council (MRC) grade or oxygen use, there was no difference in step count between patients admitted for 2-3 days (short stay) and those admitted for 7-14 days (long stay).

Patients move little during their hospitalization, and inpatient PA did not increase during their stay. A wear time criterion of 11 waking hours on any single day was representative of the entire admission whilst retaining an acceptable proportion of the initial sample size. Patients may need encouragement to move more during their hospital stay.