Airway Defense Research Articles

“Deciphering The Enigma Of Nasal & Paranasal Anatomy Through Computed Tomography (CT) Imaging”

Introduction: the paranasal sinuses are mucosa-lined structures physically contiguous with the nasal cavity that aid in insulation, reducing cranial weight, heating & humidifying the air, imparting resonance to the voice, providing airway defense and simply to replace functionless bone. Sinusitis is rarely life threatening, but the complex anatomy of the facial planes, the associated venous and lymphatic spread and the close location to the central nervous system can lead on to serious complications. It is, therefore, important to understand the normal anatomy of the paranasal sinuses in order to understand the pathogenesis of sinus disease. Hence, the aim of the present study was deciphering the role of ct as the investigation of choice for the preoperative evaluation of the nose & paranasal sinuses and for delineation of obstructive inflammatory sinus disease to aid in the diagnosis and management of recurrent & chronic disease and to define the bony anatomy before surgery. Materials and methods: prospective cross-sectional study was conducted on 100 asymptomatic patients who were getting investigated by computed tomography for non-sinus indications in whom the paranasal sinus region could be included in the field of study referred to department of radio-diagnosis and imaging from indoor and outdoor departments of jan sewa hospital of dr. S. S. Tantia medical college, sri ganganagar. Results: the majority of patients were in the age group of 21-40 years (42.3%) with 70% being male. Patients in the age group equaling or more than 61 years & with diabetes had the most number of incidental findings (68.2 %) agger nasi was the commonest anatomical paranasal sinus variant (82.9 %) followed by concha bullosa (39.3 %), deviation of the nasal septum (35.4 %), onodi cells ( 12.2 %) & haller cells ( 11.8 %). Incidental paranasal sinus abnormality in the form of mucosal thickening, sinus secretions or polyps were detected in 51.9 % patients, mucosal thickening being most common (40.1 %) followed by secretions (31.9 %) and mucosal polyps ( 3.0 %). Incidental paranasal abnormalities were most commonly noted in the ethmoid sinuses (36.7 %) followed by the maxillary sinuses, sphenoid sinuses and then frontal sinuses in descending order of involvement. Conclusion: computed tomography (ct) provides a “road map” for diagnosis and management of recurrent & chronic paranasal sinus disease and to delineate the bony anatomy before sinus surgery and to get an insight into anatomical variants apropos of their clinical relevance & impact on sinus disease.

“Deciphering The Enigma Of Nasal & Paranasal Anatomy Through Computed Tomography (CT) Imaging”

Introduction: the paranasal sinuses are mucosa-lined structures physically contiguous with the nasal cavity that aid in insulation, reducing cranial weight, heating & humidifying the air, imparting resonance to the voice, providing airway defense and simply to replace functionless bone. Sinusitis is rarely life threatening, but the complex anatomy of the facial planes, the associated venous and lymphatic spread and the close location to the central nervous system can lead on to serious complications. It is, therefore, important to understand the normal anatomy of the paranasal sinuses in order to understand the pathogenesis of sinus disease. Hence, the aim of the present study was deciphering the role of ct as the investigation of choice for the preoperative evaluation of the nose & paranasal sinuses and for delineation of obstructive inflammatory sinus disease to aid in the diagnosis and management of recurrent & chronic disease and to define the bony anatomy before surgery. Materials and methods: prospective cross-sectional study was conducted on 100 asymptomatic patients who were getting investigated by computed tomography for non-sinus indications in whom the paranasal sinus region could be included in the field of study referred to department of radio-diagnosis and imaging from indoor and outdoor departments of jan sewa hospital of dr. S. S. Tantia medical college, sri ganganagar. Results: the majority of patients were in the age group of 21-40 years (42.3%) with 70% being male. Patients in the age group equaling or more than 61 years & with diabetes had the most number of incidental findings (68.2 %) agger nasi was the commonest anatomical paranasal sinus variant (82.9 %) followed by concha bullosa (39.3 %), deviation of the nasal septum (35.4 %), onodi cells ( 12.2 %) & haller cells ( 11.8 %). Incidental paranasal sinus abnormality in the form of mucosal thickening, sinus secretions or polyps were detected in 51.9 % patients, mucosal thickening being most common (40.1 %) followed by secretions (31.9 %) and mucosal polyps ( 3.0 %). Incidental paranasal abnormalities were most commonly noted in the ethmoid sinuses (36.7 %) followed by the maxillary sinuses, sphenoid sinuses and then frontal sinuses in descending order of involvement. Conclusion: computed tomography (ct) provides a “road map” for diagnosis and management of recurrent & chronic paranasal sinus disease and to delineate the bony anatomy before sinus surgery and to get an insight into anatomical variants apropos of their clinical relevance & impact on sinus disease.

The impact of expiratory muscle strength training on voluntary cough effectiveness in Huntington's disease.

Dysfunction of the airway defence system in Huntington's disease (HD) is a significant but often overlooked problem. Although expiratory muscle strength training (EMST) is frequently utilized in cough effectiveness treatment, its specific impact in HD patients has not yet been explored. This study investigated the effects of EMST on voluntary peak cough flow (vPCF) in HD patients and evaluated the retention of potential gains post-intervention. In this prospective case-controlled trial, 29 HD patients completed an 8-week wait-to-start period, which served to identify the natural development of expiratory muscle strength and vPCF. This was followed by 8 weeks of EMST training and an additional 8 weeks of follow-up. The study's outcome parameters, vPCF and maximum expiratory pressure (MEP), were measured against those of age- and sex-matched healthy controls. Huntington's disease patients had significantly lower MEP (p < 0.001) and vPCF (p = 0.012) compared to healthy controls at baseline. Following the EMST, significant improvements in MEP (d = 1.39, p < 0.001) and vPCF (d = 0.77, p = 0.001) were observed, with HD patients reaching the cough performance levels of healthy subjects. However, these gains diminished during the follow-up, with a significant decline in vPCF (d = -0.451, p = 0.03) and in MEP (d = -0.71; p = 0.002). Expiratory muscle strength training improves expiratory muscle strength and voluntary cough effectiveness in HD patients, but an ongoing maintenance programme is necessary to sustain the improvements.

Amygdalar involvement in respiratory dysfunction.

The brainstem has long been recognized as the major respiratory control center, but it has become increasingly appreciated that areas upstream of the brainstem modulate respiration and airway defensive behaviors. This review aims to define the role of the amygdala, a key temporal brain region essential for limbic function, in respiration and airway defenses. We summarize literature describing roles for the amygdala in control of respiration, swallow, cough, airway smooth muscle contraction, and mucus secretion. We emphasize the need to understand how the amygdala regulates these functions both at a local scale and network scale and identify knowledge gaps for current and future investigations. Lastly, we highlight literature suggesting that amygdala dysfunction may contribute to respiratory dysfunction.

Cough effectiveness during airway invasion in adults with oropharyngeal dysphagia: A systematic review of literature

BACKGROUND: Cough and swallowing share common neuroanatomic pathways, leading to an overlap between their mechanisms. Despite the widely recognised role of cough as an airway defence mechanism, empirical evidence supporting its effectiveness for airway clearance is lacking. OBJECTIVE: This review summarises and appraises available evidence regarding the effectiveness of cough in response to airway penetration and/or aspiration during videofluoroscopic swallow study (VFSS) or flexible endoscopic evaluation of swallowing (FEES) in adults with oropharyngeal dysphagia (OD) of any aetiology. METHODS: The Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines were followed. Literature search was conducted in March 2023 and updated in March 2024 across six databases without publication status, language, or date restrictions. Two independent reviewers performed screening, with disagreements resolved through consensus and majority vote. The principal investigator conducted data extraction and quality appraisal using the Downs and Black checklist. RESULTS: Of 6,049 studies retrieved, 25 met the eligibility criteria. Due to heterogeneous reporting, a summary of participant demographics could not be compiled. Absence of a standardised method for measuring cough effectiveness meant meta-analysis was impossible. Nonetheless, an effective cough response to penetration/aspiration was noted for some participants within 17 studies, ineffective cough responses for some within 17 studies, while one study reported a partially effective cough response for participants. CONCLUSIONS: Robust evidence on cough effectiveness is lacking due to study heterogeneity and inconsistent reporting. Developing a standardised tool to assess cough effectiveness would ensure consistency and comparability across studies, improving clinical reporting of VFSS and FEES outcomes.

Adenylate cyclase 6 targets in Mucociliary Clearance

Background. Mucociliary clearance (MCC) is a frontline airway defense mechanism that relies on the appropriate interactions between the epithelium, ciliary beat frequency, and the quantity and quality of mucus. MCC is severely impaired in cystic fibrosis (CF) and drives lung function decline and ultimate respiratory failure and death. A great need remains to identify the key molecular players that regulate MCC in CF outside the scope of FDA approved CFTR therapy and to specifically target MCC dysfunction in CF using small molecules. Results. We discover a novel key role of cAMP-synthesizing enzyme Adenylate cyclase 6 (AC6) in MCC via (a) regulation of CFTR chloride channels in the secretory cells that generate airway surface liquid (ASL) component of MCC and (b) AC6 mediated regulation of ciliary beat frequency in the ciliated cells that is required for the mechanical clearance. Specific activators of AC6 (C20: Top candidate) were developed and improved MCC process ex vivo in CF explant tissues and cells. Together these mechanisms and small molecule approach that improve airway fluid balance and cilia function could be beneficial in CF and other respiratory diseases. Experimental Approach. We performed CFTR functional assessment in normal and CF patient derived airway epithelial cells by adapting patch-sequencing approach and using the specific activators of AC6. The effect of AC6 activators on MCC will be evaluated ex vivo in patient derived lung explant tissues , in vivo (micro-CT) in CF rat models and in vitro (ciliary beat frequency and bead flow measurements) in air-liquid interface airway epithelial cultures. Overall, these studies will be mechanistic and translational involving human disease specimens, animal models, drug development and computational analysis. Significance of the results. The proposed research can improve our understanding of epithelial biology and advance activators of AC6 as therapeutic agents to treat mucus clearance defects. These findings can be leveraged to modulate CFTR function and cilia-generate flow, presenting a potential therapeutic avenue for conditions that involve CFTR and cilia dysregulation associated with several respiratory diseases. National Institutes of Health (NIH) DK080834 and P30-DK117467 and HL147351 (to APN). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Mucus Structure, Viscoelastic Properties, and Composition in Chronic Respiratory Diseases.

The respiratory mucus, a viscoelastic gel, effectuates a primary line of the airway defense when operated by the mucociliary clearance. In chronic respiratory diseases (CRDs), such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), the mucus is overproduced and its solid content augments, changing its structure and viscoelastic properties and determining a derangement of essential defense mechanisms against opportunistic microbial (virus and bacteria) pathogens. This ensues in damaging of the airways, leading to a vicious cycle of obstruction and infection responsible for the harsh clinical evolution of these CRDs. Here, we review the essential features of normal and pathological mucus (i.e., sputum in CF, COPD, and asthma), i.e., mucin content, structure (mesh size), micro/macro-rheology, pH, and osmotic pressure, ending with the awareness that sputum biomarkers (mucins, inflammatory proteins and peptides, and metabolites) might serve to indicate acute exacerbation and response to therapies. There are some indications that old and novel treatments may change the structure, viscoelastic properties, and biomarker content of sputum; however, a wealth of work is still needed to embrace these measures as correlates of disease severity in association with (or even as substitutes of) pulmonary functional tests.

Cough: An Introductory Guide for Speech-Language Pathologists

Purpose: The airway defense mechanism of cough is essential for human survival. Recognition is growing about the distinct role of speech-language pathologists in the nonpharmacological management of various cough disorders. This clinical focus article aims to deliver relevant education about normal and pathological cough to strengthen existing clinical knowledge and skills. Conclusions: The neuronal pathways underlying normal cough function are complex. Cough problems refer to either reduced or heightened cough stemming from various disease processes, and both clinical presentations have detrimental consequences. Current evidence supports that patients who suffer from cough dysfunction benefit from nonpharmacological interventions offered via speech therapy as an adjunct to medical treatments. Speech therapy strategies apply the higher cognitive components of cough by focusing on the deliberate modification and coordination of respiration. Future research priorities are positioned toward improving clinical outcomes for cough disorders.

Olfactory immunology: the missing piece in airway and CNS defence.

The olfactory mucosa is a component of the nasal airway that mediates the sense of smell. Recent studies point to an important role for the olfactory mucosa as a barrier to both respiratory pathogens and to neuroinvasive pathogens that hijack the olfactory nerve and invade the CNS. In particular, the COVID-19 pandemic has demonstrated that the olfactory mucosa is an integral part of a heterogeneous nasal mucosal barrier critical to upper airway immunity. However, our insufficient knowledge of olfactory mucosal immunity hinders attempts to protect this tissue from infection and other diseases. This Review summarizes the state of olfactory immunology by highlighting the unique immunologically relevant anatomy of the olfactory mucosa, describing what is known of olfactory immune cells, and considering the impact of common infectious diseases and inflammatory disorders at this site. We will offer our perspective on the future of the field and the many unresolved questions pertaining to olfactory immunity.

Age influences the specific force and fatigability of the external abdominal obliques but not pectoralis major muscles

In the elderly, airway infections are associated with impaired airway defense behaviors, leading to an increased risk of airway infection. The muscles of the chest and abdominal wall are essential for performing effective airway defense manoeuvres, however, very little is known about their function in aging. Here in the 6- and 24-months old Fischer 344 rat model of aging, we assess the contractility and fatigability of chest (the pectoralis major muscle) and abdominal wall (external abdominal oblique) muscles. We assessed muscle function using an ex vivo approach, measuring isometric specific forces normalised to muscle CSA, via a platinum plate field stimulations at a range of frequencies (5–150 Hz) for 1 s. Surprisingly, we did not observe any effect of age on the specific force and fatigue properties of the pectoral muscle. However, in 24-months old rats, EAO specific force was reduced by ∼32 %. These finding suggest that not all respiratory muscles are equally vulnerable to age-associated weakness.

Effects of TRPV4 channel blocker on airway inflammation and airway defense reflexes in experimentally induced model of allergic asthma

The transient receptor potential (TRP) channels regulate physiological and pathological processes. Changes in their activity and sensitivity may be involved in the pathophysiology of asthma. The present study investigates the effect of an inhaled TRPV4 channel blocker HC-067047 in an experimental guinea pig model of ovalbumin-induced allergic asthma. We monitored the effect of 50 nM, 100 nM, and 150 nM HC-067047 concentrations on airway defense reflexes in vivo and tracheal smooth muscle contractility in vitro. The anti-inflammatory action of HC-067047 was investigated by analysis of chronic inflammation markers from lung homogenates. The results suggest that HC-067047 can suppress airway defense reflexes in vivo and acetylcholine-induced contractility in vitro. Immunological analysis revealed that TRPV4 channel blockade leads to a decrease in the levels of inflammatory cytokines. An effect on airway defence reflexes and airway inflammation was observed using tested concentrations (50 mM, 100 mM, 150 mM) of HC-067047. The effects of HC-067047 on both airway defense reflexes and inflammation underline the role of TRPV4 channels in asthma and uncover therapeutic targets for developing innovative drugs in asthma therapy.

Bronchiectasis: From targets to therapies

Bronchiectasis is a chronic obstructive airway disease characterized by abnormal bronchial dilatation and the accumulation of muco-purulent endoluminal secretions. Progressive lung function deterioration, frequent bouts of respiratory infection and daily productive cough negatively impact the lives of affected individuals. Multiple causal factors can initiate bronchiectasis; however, defects in host defenses represent a cardinal feature. The first line of airway defense against inhaled pathogens is mucociliary clearance. Systemic host defense defects, particularly those affecting opsonophagocytosis and killing of bacteria are equally essential to prevent bronchiectasis. Substantial evidence suggests that unopposed neutrophil protease activity in the airway lumen leads to the loss of bronchial elasticity and excessive accumulation of mucus. The focus of this review is on the advances in our understanding of pathogenic mechanisms that are bringing new targeted therapies for individuals suffering from the clinical manifestations of bronchiectasis.

Butyrate silences MUC5ACexpression in airway epithelial cells by mediating histone deacetylation at its transcription start site

Abstract Secreted airway mucins form a mucous gel consisting of MUC5AC and MUC5B and maintain airway homeostasis for appropriate mucociliary clearance and airway defense. There is conceivably a global mechanism to counteract excessive mucin production in response to incessant exposure to external and internal stimuli, which otherwise leads to goblet metaplasia and mucus hyperproduction. Here, we report that butyrate, a short-chain fatty acid (SCFA), strongly suppresses MUC5AC production at as low as sub-to micromolar concentrations in NCI-H292, airway epithelial cells. Butyrate transcriptionally inhibits MUC5AC mRNA and protein that are induced by a variety of stimuli including EGF and LPS. In line, butyrate upregulates FOXA2, which is known to block goblet cell metaplasia. The mode of the inhibition by butyrate appears to be independent of the known receptors of butyrate. In addition, butyrate does not alter the EGFR signaling pathway. Chromatin immunoprecipitation analysis demonstrates that histone H3K27 acetylation level is increased upon stimulation with EGF and returns to baseline in the presence of butyrate. We propose that butyrate, a metabolic product of gut microbiota, plays a central role in maintaining homeostasis of airway mucous gel by counteracting mucin production resulting from repeated provocation of airway epithelium. National Research Foundation of Korea (NRF) funded by the Korean government (MSIT), NRF-2022R1A2B5B01002127.

Size-dependent differences in mitochondrial volume density in phrenic motor neurons.

Neuromotor control of diaphragm muscle (DIAm) motor units is dependent on an orderly size-dependent recruitment of phrenic motor neurons (PhMNs). Slow (type S) and fast, fatigue resistant (type FR) DIAm motor units, which are frequently recruited to sustain ventilation, comprise smaller PhMNs that innervate type I and IIa DIAm fibers. More fatigable fast (type FF) motor units, which are infrequently recruited for higher force, expulsive behaviors, comprise larger PhMNs that innervate more type IIx/IIb DIAm fibers. We hypothesize that due to the more frequent activation and thus higher energy demand of type S and FR motor units, the mitochondrial volume density (MVD) of smaller PhMNs is greater compared with larger PhMNs. In eight adult (6 mo old) Fischer 344 rats, PhMNs were identified via intrapleural injection of Alexa488-conjugated cholera toxin B (CTB). Following retrograde CTB labeling, mitochondria in PhMNs were labeled by transdural infusion of MitoTracker Red. PhMNs and mitochondria were imaged using multichannel confocal microscopy using a ×60 oil objective. Following optical sectioning and three-dimensional (3-D) rendering, PhMNs and mitochondria were analyzed volumetrically using Nikon Elements software. Analysis of MVD in somal and dendritic compartments was stratified by PhMN somal surface area. Smaller PhMNs (likely S and FR units) had greater somal MVDs compared with larger PhMNs (likely FF units). By contrast, proximal dendrites or larger PhMNs had higher MVD compared with dendrites of smaller PhMNs. We conclude that more active smaller PhMNs have a higher mitochondrial volume density to support their higher energy demand in sustaining ventilation.NEW & NOTEWORTHY Type S and FR motor units, comprising smaller phrenic motor neurons (PhMNs) are regularly activated to perform indefatigable ventilatory requirements. By contrast, type FF motor units, comprising larger PhMNs, are infrequently activated to perform expulsive straining and airway defense maneuvers. This difference in activation history is mirrored in the mitochondrial volume density (MVD), with smaller PhMNs having higher MVD than larger PhMNs. In proximal dendrites, this trend was reversed, with larger PhMNs having higher MVD than smaller PhMNs, likely due to the maintenance requirements for the larger dendritic arbor of FF PhMNs.

Air pollution and respiratory health-Do we really need more evidence?

Air pollution and respiratory health-Do we really need more evidence?

The effect of oral care using honey as an additional topical agent on oral health status of intubated patients in the intensive care unit

BackgroundPatients using endotracheal tubes are at high risk of oral health status dysfunction due to impaired natural airway defence, oral flora composition changes and protective substances of the teeth, medication causing xerostomia. Oral care has not been enough to manage oral mucosal dryness, so an additional topical agent is needed to protect oral mucosa to maintain oral health. Honey is one of the recommended topical agents. ObjectiveThis study aims to identify the effect of oral care with honey as topical agents on the oral health status of patients using endotracheal tube in the Intensive Care Unit. MethodsThis was an experimental study with a randomized pretest and posttest design. The sample was adult intubated patients, consisting of 36 patients. The data were analysed using the parametric test, and dependent and independent t-test. ResultsThe oral health score in the control group was found to be pre & post mean score11.94 and 13.28 (p=.004) respectively, while in the intervention group 11.89 and 8.33 (p<.001). Mean differences in both groups were 4.95 (p<.001) and the BOAS subscale differences were seen on the lips, gums & mucosa, and tongue (p<.05). ConclusionOral care with honey as a topical agent can improve the oral health status of intubated patients on the lips, gum, mucosa, and tongue subscale. Therefore, honey as an additional topical agent can be a moisturizer to maintain the oral mucosa for intubated patients in the Intensive Care Unit. Furthermore, good mucosal health will help prevent the infection and colonization of microorganisms.

Healthy Human Laryngopharyngeal Sensory Innervation Density Correlates with Age.

Somatosensory feedback from upper airway structures is essential for swallowing and airway defense but little is known about the identities and distributions of human upper airway neurons. Furthermore, whether sensory innervation modifies with aging is unknown. In this study, we quantify neuronal and chemosensory cell density in upper airway structures and correlate with age. Participants underwent biopsies from base of tongue, lateral and midline pharyngeal wall, epiglottis, and arytenoids (N=25 13 female/12 male; 20-80 years, mean 51.4 years without clinical diagnosis of dysphagia or clinical indication for biopsy). Tissue sections were labeled with antibodies for all neurons, myelinated neurons, and chemosensory cells. Densities of lamina propria innervation, epithelial innervation, solitary chemosensory cells, and taste buds were calculated and correlated with age. Arytenoid had the highest density of innervation and chemosensory cells across all measures compared to other sites. Taste buds were frequently observed in arytenoid and epiglottis. Base of tongue, lateral pharynx, and midline posterior pharynx had minimal innervation and few chemosensory cells. Epithelial innervation was present primarily in close proximity to chemosensory cells and taste buds. Overall innervation and myelinated fibers in the arytenoid lamina propria decline with aging. Findings establish the architecture of healthy adult sensory innervation and demonstrate the varied distribution of laryngopharyngeal innervation, necessary steps toward understanding the sensory basis for swallowing and airway defense. We also document age-related decline in arytenoid innervation density. These findings suggest that sensory afferent denervation of the upper airway may be a contributing factor to presbyphagia. NA Laryngoscope, 133:773-784, 2023.

MiR449 Protects Airway Regeneration by Controlling AURKA/HDAC6-Mediated Ciliary Disassembly.

Airway mucociliary regeneration and function are key players for airway defense and are impaired in chronic obstructive pulmonary disease (COPD). Using transcriptome analysis in COPD-derived bronchial biopsies, we observed a positive correlation between cilia-related genes and microRNA-449 (miR449). In vitro, miR449 was strongly increased during airway epithelial mucociliary differentiation. In vivo, miR449 was upregulated during recovery from chemical or infective insults. miR0449−/− mice (both alleles are deleted) showed impaired ciliated epithelial regeneration after naphthalene and Haemophilus influenzae exposure, accompanied by more intense inflammation and emphysematous manifestations of COPD. The latter occurred spontaneously in aged miR449−/− mice. We identified Aurora kinase A and its effector target HDAC6 as key mediators in miR449-regulated ciliary homeostasis and epithelial regeneration. Aurora kinase A is downregulated upon miR449 overexpression in vitro and upregulated in miR449−/− mouse lungs. Accordingly, imaging studies showed profoundly altered cilia length and morphology accompanied by reduced mucociliary clearance. Pharmacological inhibition of HDAC6 rescued cilia length and coverage in miR449−/− cells, consistent with its tubulin-deacetylating function. Altogether, our study establishes a link between miR449, ciliary dysfunction, and COPD pathogenesis.

The effect of Ramadan fasting on nasal mucociliary activity and peak nasal inspiratory flow.

In this study, we aimed to investigate the effect of Ramadan fasting (RF) on nasal mucociliary clearance (MCC) and peak nasal inspiratory flow (PNIF). Sixty-two (41 male and 21 female) healthy subjects who stated that they would fast continuously during the month of Ramadan were included in this prospective study. Day 0 (baseline), 1st day (after one day of RF), and 29th (after 29days of RF) nasal mucociliary clearance time (MCT) with saccharine test and PNIF values were determined. Subject weights (SW) were measured on Day 0 and Day 29. The obtained data were analyzed statistically. The mean of SW on day 0 was 78.53 ± 10.95kg, and the mean of SW on Day 29 was 78.69 ± 10.87kg. There was no significant difference in terms of SW (p = 0.251, p > 0.05). A significant difference was found between the MCT and PNIF values measured on different study days (p < 0.05). The MCT values for Day 29 were significantly higher than the values for other days (p < 0.05). There was no significant difference between the MCT values on the first day and the baseline (p = 0.891, p > 0.05). The PNIF values for Day 29 were significantly higher than the values for other days (p < 0.05). The PNIF values on the first day were significantly higher than the baseline (p = 0.008, p < 0.05). The present study showed that RF leads to MCT prolongation and PNIF increase. Ramadan fasting causes deterioration in nasal airway defense and improvement in nasal respiration.

Neuroanatomical and neurophysiological evidence of pulmonary nociceptor and carotid chemoreceptor convergence in the nucleus tractus solitarius and nucleus ambiguus.

Pulmonary vagal nociceptors defend the airways. Cardiopulmonary vagal nociceptors synapse in the nucleus tractus solitarius (NTS). Evidence has demonstrated the convergence of cardiopulmonary nociceptors with afferents from carotid chemoreceptors. Whether sensory convergence occurs in motor nuclei and how sensory convergence affects reflexive efferent motor output directed toward the airways are critical knowledge gaps. Here, we show that distinct tracer injection into the pulmonary nociceptors and carotid chemoreceptors leads to co-labeled neurons in the nucleus tractus solitarius and nucleus ambiguus. Precise simultaneous stimulation delivered to pulmonary nociceptors and carotid chemoreceptors doubled efferent vagal output, enhanced phrenic pause, and subsequently augmented phrenic motor activity. These results suggest that multiple afferents are involved in protecting the airways and concurrent stimulation enhances airway defensive reflex output.NEW & NOTEWORTHY Sensory afferents have been shown to converge onto nucleus tractus solitarius primary neurons. Here, we show sensory convergence of two distinct sets of sensory afferents in motor nuclei of the nucleus ambiguus, which results in augmentation of airway defense motor output.