In a healthy human, the airway mucus forms a thin, protective liquid layer covering the surface of the respiratory tract. It comprises a complex blend of mucin, multiple antibacterial proteins, metabolic substances, water, and electrolytes. This mucus plays a pivotal role in the lungs' innate immune system by maintaining airway hydration and capturing airborne particles and pathogens. However, heightened mucus secretion in the airway can compromise ciliary clearance, obstruct the respiratory tract, and increase the risk of pathogen colonization and recurrent infections. Consequently, a thorough exploration of the mechanisms driving excessive airway mucus secretion is crucial for establishing a theoretical foundation for the eventual development of targeted drugs designed to reduce mucus production. Across a range of lung diseases, excessive airway mucus secretion manifests with unique characteristics and regulatory mechanisms, all intricately linked to mucin. This article provides a comprehensive overview of the characteristics and regulatory mechanisms associated with excessive airway mucus secretion in several prevalent lung diseases.
Humans ; Mucus/metabolism* ; Mucins/physiology* ; Lung Diseases/metabolism* ; Respiratory Mucosa/metabolism* ; Pulmonary Disease, Chronic Obstructive/physiopathology* ; Asthma/physiopathology* ; Cystic Fibrosis/physiopathology* ; Mucociliary Clearance/physiology*

In order to accurately capture the respiratory muscle movement and extract the synchronization signals corresponding to the breathing phases, a comprehensive signal sensing system for sensing the movement of the respiratory muscle was developed with applying the thin-film varistor FSR402 IMS-C07A in this paper. The system integrated a sensor, a signal processing circuit, and an application program to collect, amplify and denoise electronic signals. Based on the respiratory muscle movement sensor and a STM32F107 development board, an experimental platform was designed to conduct experiments. The respiratory muscle movement data and respiratory airflow data were collected from 3 healthy adults for comparative analysis. In this paper, the results demonstrated that the method for determining respiratory phase based on the sensing the respiratory muscle movement exhibited strong real-time performance. Compared to traditional airflow-based respiratory phase detection, the proposed method showed a lead times ranging from 33 to 210 ms [(88.3 ± 47.9) ms] for expiration switched into inspiration and 17 to 222 ms [(92.9 ± 63.8) ms] for inspiration switched into expiration, respectively. When this system is applied to trigger the output of the ventilator, it will effectively improve the patient-ventilator synchrony and facilitate the ventilation treatment for patients with respiratory diseases.
Humans ; Respiratory Muscles/physiology* ; Signal Processing, Computer-Assisted ; Movement/physiology* ; Respiration ; Monitoring, Physiologic/methods* ; Adult

OBJECTIVES: To investigate the efficacy of volume-guaranteed high-frequency oscillatory ventilation (HFOV-VG) in preterm infants with respiratory distress syndrome (RDS) and its impact on blood flow in the middle cerebral artery (MCA). METHODS: A prospective study was conducted on 120 preterm infants with RDS who were admitted to the Department of Neonatology at Qinhuangdao Maternal and Child Health Hospital from March 2020 to December 2023. According to the mode of ventilation, the infants were divided into two groups: a conventional mechanical ventilation (CMV) group (60 infants) and an HFOV-VG group (60 infants). The two groups were compared in terms of baseline data, MCA hemodynamic parameters, complications, and outcomes. RESULTS: Compared with the CMV group, the HFOV-VG group had significantly shorter durations of mechanical ventilation and hospital stay and a significantly higher overall response rate (P<0.05). The HFOV-VG group demonstrated significantly better peak systolic velocity, end-diastolic velocity, and mean flow velocity (P<0.05). The HFOV-VG group also exhibited significantly lower 28-day mortality rates and lower incidence rates of bronchopulmonary dysplasia and intraventricular hemorrhage than the CMV group (P<0.05). CONCLUSIONS HFOV-VG can effectively improve cerebral blood perfusion, reduce cerebrovascular resistance, shorten the durations of mechanical ventilation and hospital stay, and enhance overall treatment efficacy. It has significant advantages in reducing the risk of 28-day mortality, bronchopulmonary dysplasia, and intraventricular hemorrhage in preterm infants with RDS.
Humans ; High-Frequency Ventilation/adverse effects* ; Infant, Newborn ; Respiratory Distress Syndrome, Newborn/physiopathology* ; Female ; Middle Cerebral Artery/physiology* ; Male ; Prospective Studies ; Cerebrovascular Circulation ; Infant, Premature

OBJECTIVES: To investigate the effect of interferon-λ1 (IFN-λ1) on glucocorticoid (GC) resistance in human bronchial epithelial cells (HBECs) stimulated by respiratory syncytial virus (RSV). METHODS: HBECs were divided into five groups: control, dexamethasone, IFN-λ1, RSV, and RSV+IFN-λ1. CCK-8 assay was used to measure the effect of different concentrations of IFN-λ1 on the viability of HBECs, and the sensitivity of HBECs to dexamethasone was measured in each group. Quantitative real-time PCR was used to measure the mRNA expression levels of p38 mitogen-activated protein kinase (p38 MAPK), glucocorticoid receptor (GR), and MAPK phosphatase-1 (MKP-1). Western blot was used to measure the protein expression level of GR in cell nucleus and cytoplasm, and the nuclear/cytoplasmic ratio of GR was calculated. RESULTS: At 24 and 72 hours, the proliferation activity of HBECs increased with the increase in IFN-λ1 concentration in a dose- and time-dependent manner (P˂0.05). Compared with the RSV group, the RSV+IFN-λ1 group had significant reductions in the half-maximal inhibitory concentration of dexamethasone and the mRNA expression level of p38 MAPK (P<0.05), as well as significant increases in the mRNA expression levels of GR and MKP-1, the level of GR in cell nucleus and cytoplasm, and the nuclear/cytoplasmic GR ratio (P<0.05). CONCLUSIONS IFN-λ1 can inhibit the p38 MAPK pathway by upregulating MKP-1, promote the nuclear translocation of GR, and thus ameliorate GC resistance in HBECs.
Humans ; p38 Mitogen-Activated Protein Kinases/genetics* ; Glucocorticoids/pharmacology* ; Receptors, Glucocorticoid/analysis* ; Dual Specificity Phosphatase 1/physiology* ; Dexamethasone/pharmacology* ; Drug Resistance/drug effects* ; Respiratory Syncytial Viruses ; Interferons/pharmacology* ; MAP Kinase Signaling System/drug effects* ; Epithelial Cells/drug effects* ; Signal Transduction/drug effects* ; Cells, Cultured

BACKGROUND: SARS-CoV-2 (COVID-19) is transmitted via infectious respiratory particles. Infectious respiratory particles are released when an infected person breathes, coughs, or speaks. Several studies have measured respiratory particle concentrations through focusing on activities such as breathing, coughing, and short speech. However, few studies have investigated the effect of speech duration. METHODS: This study aimed to clarify the effects of speech duration and volume on the respiratory particle concentration. Study participants were requested to speak at three voice volumes across five speech durations, generating 15 speech patterns. Participants spoke inside a clean booth where particle concentrations and voice volumes were measured and analyzed during speech. RESULTS: Our findings suggest that as speech duration increased, the aerosol number concentration also increased. Through focusing on individual differences, we considered there might be super-emitters who emit more aerosol particles than the average human. Two participants were identified as statistical outliers (aerosol number concentration, n = 1; mass concentration, n = 1). CONCLUSIONS Considering speech duration may improve our understanding of respiratory particle concentration dynamics. Two participants were identified as potential super-emitters.
Humans ; Male ; Speech/physiology* ; Adult ; Female ; COVID-19/transmission* ; Respiratory Aerosols and Droplets ; Voice ; SARS-CoV-2 ; Time Factors ; Young Adult ; Aerosols/analysis*

OBJECTIVE: To investigate the effect of traditional Chinese Five-body balance exercise on patients with preserved ratio impaired spirometry (PRISm). METHODS: Fifteen patients with PRISm and 15 patients diagnosed with chronic obstructive pulmonary disease (COPD) were recruited from the Outpatient Department of Guang'anmen Hospital and Beijing Niujie Health Service Center from April to December, 2023. Participants in both groups attended supervised Five-body balance exercise training twice a week for 12 weeks. Patients with COPD continued their regular medication regimen during the intervention period. The endpoints were mean changes in the 6-min walk test (6MWT), St. George's Respiratory Questionnaire (SGRQ) score, cardiopulmonary exercise testing (CPET), pulmonary function, and scores of COPD assessment test (CAT), modified British Medical Research Council, Self-Rating Anxiety Scale, and Self-Rating Depression Scale from baseline to 12 weeks. Adverse events were monitored throughout the study. RESULTS: The PRISm group showed a significant improvement from baseline to week 12 in 6MWT, SGRQ symptom score, and forced vital capacity (FVC) compared to the COPD group (P<0.05). No significant between-group changes were observed in other outcome measurements (P>0.05). In addition, compared with baseline, both groups exhibited improvements in 6MWT, SGRQ score, and CPET at week 12 (P<0.05). The PRISm group also showed a significant increase in forced expiratory volume in 1 s and FVC, as well as a significant decrease in CAT score at week 12 (P<0.05). No adverse events were reported. CONCLUSION Patients with PRISm may benefit from Five-body balance exercise training, which can improve the exercise capacity, health-related quality of life, and lung function. (Registration No. ChiCTR2200059290).
Humans ; Spirometry ; Male ; Female ; Pulmonary Disease, Chronic Obstructive/therapy* ; Lung/physiopathology* ; Middle Aged ; Exercise Tolerance/physiology* ; Exercise Therapy ; Aged ; Medicine, Chinese Traditional ; Respiratory Function Tests ; East Asian People

Porcine reproductive and respiratory syndrome (PRRS), caused by the porcine reproductive and respiratory syndrome virus (PRRSV), is one of the major diseases threatening the swine industry. This study aims to rationally design and optimize natural antimicrobial peptides to identify antiviral candidates with potent inhibitory activity against PRRSV, thereby establishing a foundation for the development of novel preventive and therapeutic agents targeting PRRS. In this study, with cecropin D (CD) as the parent peptide, three derivatives (CD-2, CD-3, and CD-4) were designed through amino acid substitutions. CD and derived peptides were obtained by solid-phase peptide synthesis. MS and reversed-phase (RP)-HPLC were employed for sequence identification, purification, and purity analysis. The secondary structures of the peptides were investigated by circular dichroism spectroscopy. CellTiter 96^® AQueous one solution cell proliferation assay was used to evaluate the cytotoxicity of the peptides. The inhibitory activities and mechanisms of the peptides against PRRSV were studied by Western blotting, RT-qPCR, and indirect immunofluorescence assay. The MS and RP-HPLC results showed that CD and derived peptides were successfully synthesized, with the purity reaching up to 95%. Circular dichroism analysis revealed that the CD derivatives exhibited more stable and abundant α-helices in a cell membrane-mimicking environment. The MTS assay indicated that all tested peptides at 100 μg/mL had negligible cytotoxicity. The experimental results of the action phase of the peptide against PRRSV demonstrated that the derived peptides significantly enhanced antiviral activities at the viral entry stage compared with the parent peptide. This enhancement was attributed to the introduction of lysine, tryptophan, and phenylalanine, which increased the hydrophobicity and positive charge of the peptides. These findings provide a theoretical basis for the application and structural optimization of antiviral peptides and may offer a new strategy for preventing and controlling PRRSV.
Porcine respiratory and reproductive syndrome virus/physiology* ; Animals ; Swine ; Antiviral Agents/chemistry* ; Porcine Reproductive and Respiratory Syndrome/virology* ; Virus Internalization/drug effects* ; Antimicrobial Peptides/chemistry*

This work aims to explore the effect of glycolysis on the replication of porcine reproductive and respiratory syndrome virus (PRRSV) in porcine alveolar macrophages (PAMs). The changes of glucose metabolism, PRRSV protein levels, PRRSV titers, and the relative expression levels of genes and proteins in PAMs were analyzed by ELISA, qPCR, virus titration, and Western blotting after PRRSV infection. The effect of hypoxia-inducible factor-1α (HIF-1α) on PRRSV replication was subsequently assessed by specific siRNAs targeting to HIF-1α. The results showed that PRRSV infection enhanced glycolysis, elevated the levels of glucose uptake and lactate in the supernatant (P<0.05 and 0.01, respectively), reduced ATP production (P<0.05), and up-regulated the expression of hexokinase 2 (HK2), 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3), and pyruvate kinase isozyme type M2 (PKM2) in PAMs (P<0.05 and 0.01, respectively). Glycolysis inhibitors down-regulated the expression of PRRSV proteins and reduced virus titers (P<0.01). The knockdown of HIF-1α by siRNAs inhibited glycolysis and lowered PRRSV titers (P<0.05). In addition, the interferon pathways inhibited by PRRSV infection were reversed by the inhibition of glycolysis. These findings may facilitate further investigation of the role of glycolysis in PRRSV replication.
Porcine respiratory and reproductive syndrome virus/physiology* ; Glycolysis ; Swine ; Animals ; Virus Replication ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics* ; Macrophages, Alveolar/metabolism* ; Porcine Reproductive and Respiratory Syndrome/virology* ; Cells, Cultured ; RNA, Small Interfering/genetics*

Mechanical ventilation has, since its introduction into clinical practice, undergone a major evolution from controlled ventilation to diverse modes of assisted ventilation. Conventional mechanical ventilators depend on flow sensors and pneumatic pressure and controllers to complete the respiratory cycle. Neurally adjusted ventilatory assist (NAVA) is a new form of assisted ventilation in recent years, which monitors the electrical activity of the diaphragm (EAdi) to provide an appropriately level of pressure support. And EAdi is the best available signal to sense central respiratory drive and trigger ventilatory assist. Unlike other ventilation modes, NAVA breathing instructions come from the center. Therefore, NAVA have the synchronous nature of the breaths and the patient-adjusted nature of the support. Compared with traditional ventilation mode, NAVA can efficiently unload respiratory muscles, relieve the risk of ventilator-induced lung injury (VILI), improve patient-ventilator coordination, enhance gas exchange, increase the success rate of weaning, etc. This article reviews the research progress of NAVA in order to provide theoretical guidance for clinical applications.
Humans ; Interactive Ventilatory Support ; Respiration, Artificial ; Positive-Pressure Respiration ; Diaphragm/physiology* ; Respiratory Muscles/physiology*

OBJECTIVE: To evaluate the feasibility and safety of Liuzijue exercise (LE) for the clinical effect in patients after cardiac surgery. METHODS: Totally 120 patients who underwent cardiac surgery and were admitted to the Cardiothoracic Intensive Care Unit of Nanjing Drum Tower Hospital between July and Oclober, 2022 were allocated to the LE group, the conventional respiratory training (CRT) group, and the control group by a random number table at a ratio of 1:1:1; 40 patients in each group. All patients received routine treatment and cardiac rehabilitation. LE group and CRT group respectively performed LE and CRT once a day for 30 min for 7 days. Control group did not receive specialized respiratory training. The forced vital capacity, forced expiratory volume in 1 s, peak inspiratory flow rate, peak expiratory flow rate, maximum inspiratory pressure, maximum expiratory pressure, modified Barthel index (MBI), and Hamilton Rating Scale for Anxiety (HAM-A) were evaluated before, after 3 and 7 days of intervention. In addition, the postoperative length of hospital stay (LOS) and the adverse events that occurred during the intervention period were compared. RESULTS: A total of 107 patients completed the study, 120 patients were included in the analysis. After 3 days of intervention, the pulmonary function, respiratory muscle strength, MBI and HAM-A of all 3 groups improved compared with that before the intervention (P<0.05 or P<0.01). Compared with the control group, pulmonary function and respiratory muscle strength were significantly improved in the CRT and LE groups (P<0.05 or P<0.01). MBI and HAM-A were significantly improved in the LE group compared with the control and CRT groups (P<0.05 or P<0.01). On the 7th day after intervention, the difference was still statistically significant (P<0.01), and was significantly different from that on the 3rd day (P<0.05 or P<0.01). In addition, on the 7th day of intervention, the pulmonary function and respiratory muscle strength in the LE group were significantly improved compared with those in the CRT group (P<0.01). MBI and HAM-A were significantly improved in the CRT group compared with the control group (P<0.01). There were no significant differences in postoperative LOS among the 3 groups (P>0.05). No training-related adverse events occurred during the intervention period. CONCLUSIONS LE is safe and feasible for improving pulmonary function, respiratory muscle strength, the ability to complete activities of daily living and for relieving anxiety of patients after cardiac surgery (Registration No. ChiCTR2200062964).
Humans ; Activities of Daily Living ; Breathing Exercises ; Cardiac Surgical Procedures/adverse effects* ; Respiratory Muscles ; Muscle Strength/physiology*