Numerical analysis of micro lunar dust deposition in the human nasal airway.

The toxicity of Lunar dust (LD) is well-known to harm astronauts' health. However, the characteristics of micro-LD deposition in the human nasal airway remains unknown, and studying it through experiments is challenging. Therefore, this study employs numerical investigations to address this issue. Our findings reveal that LD larger than 4 µm primarily (>50%) deposit in the nasal cavity at an inspiration flow rate of Q= 40 L/min, while LD smaller than 8 µm are more likely (>50%) to enter the lung lobe at Q= 15 L/min. The right upper lung lobe receives a higher deposit fraction of LD compared to other lobes, reaching a maximum of 31%. The ratio of deposition fraction in the right lung and left lung can reach to 3.0. Accurately predicting LD deposition in the upper airway and entire lung is possible using mathematical expressions, but the prediction becomes more challenging for the bronchial airway and lung lobes. These results indicate that micro-LD deposition characteristics in the human nasal airway are influenced by LD size and astronauts' activity level. The deposition fractions can be used to assess the health risk from lunar dust to astronauts and provide insights into developing protective measures against LD exposure.

Biomechanical Evaluation of Tracheal Needle Puncture Forces: Comparative Analysis of Annular Ligaments and Tracheal Cartilage.

Percutaneous tracheotomies (PCT) are commonly performed minimally invasive procedures involving the creation of an airway opening through an incision or puncture of the tracheal wall. While the medical intervention is crucial for critical care and the management of acute respiratory failure, tracheostomy complications can lead to severe clinical symptoms due to the alterations of the airways biomechanical properties/structures. The causes and mechanisms underlaying the development of these post-tracheotomy complications remain largely unknown. In this study, we aimed to investigate the needle puncture process and its biomechanical characteristics by using a well establish porcine ex vivo trachea to simulate the forces involved in accessing airways during PCT at varying angular approaches. Given that many procedures involve inserting a needle into the trachea without direct visualization of the tracheal wall, concerns have been raised over the needle punctures through the cartilaginous rings as compared to the space between them may result in fractured cartilage and post-tracheostomy airway complications. We report a difference in puncture force between piercing the cartilage and the annular ligaments and observe that the angle of puncture does not significantly alter the puncture forces. The data collected in this study can guide the design of relevant biomechanical feedback system during airway access procedures and ultimately help refine and optimize PCT.

Cell-Mediated Branch Fusion in the Drosophila Trachea.

The Drosophila trachea is an interconnected network of epithelial tubes, which delivers gases throughout the entire organism. It is the premier model to study the development of tubular organs, such as the human lung, kidney, and blood vessels. The Drosophila embryonic trachea derives from a series of segmentally repeated clusters. The tracheal precursor cells in each cluster migrate out in a stereotyped pattern to form primary branches. Thereafter, the neighboring branches need to fuse to form an interconnected tubular network. The connection between neighboring branches is orchestrated by specialized cells, called fusion cells. These cells fuse with their counterparts to form a tube with a contiguous lumen. Branch fusion is a multi-step process that includes cell migration, cell adhesion, cytoskeleton track formation, vesicle trafficking, membrane fusion, and lumen formation. This review summarizes the current knowledge on fusion process in the Drosophila trachea. These mechanisms will greatly contribute to our understanding of branch fusion in mammalian systems.

[Features of surgical treatment of central tracheal and bronchial carcinoid]. / Osobennosti khirurgicheskogo lecheniya tsentral'nogo kartsinoida trakhei i bronkhov.

OBJECTIVE: To analyze features of surgical treatment of central tracheal and bronchial carcinoid. MATERIAL AND METHODS: A retrospective analysis included 115 patients with carcinoid tracheal and bronchial tumors who have been examined and treated from 1974 to the present. The majority of patients (97, 84.3%) had central form of carcinoid of the trachea, bronchi and lungs. Of these, 95 (97.9%) ones underwent surgical treatment. RESULTS: We used pre- and intraoperative diagnostics including bronchotomy. This approach provided organ-sparing surgery with resection and reconstruction of the bronchi and trachea in 71 (74.7%) patients including complete preservation of lung function in 20 (21.1%) cases and lobectomy/segmentectomy with resection and reconstruction of the bronchi in 51 (53.7%) cases. Two patients underwent pneumonectomy with wedge-shaped and marginal resection and reconstruction of tracheal bifurcation. Postoperative complications developed in 4 (4.2%) patients, and 2 (2.1%) ones died. Overall 5-year survival after radical surgeries was 89.2% (100% in typical carcinoid and 78.0% in atypical carcinoid).

Airway management for a patient with tracheobronchomegaly undergoing lobectomy: a case report.

BACKGROUND: Tracheobronchomegaly (TBM) is a rare disorder mainly characterized by dilatation and malacia of the trachea and major bronchi with diverticularization. This will be a great challenge for airway management, especially in thoracic surgery requiring one-lung ventilation. Using a laryngeal mask airway and a modified double-lumen Foley catheter (DFC) as a "blocker" may achieve one-lung ventilation. This is the first report introducing this method in a patient with TBM. CASE PRESENTATION: We present a 64-year-old man with TBM receiving left lower lobectomy. Preoperative chest computed tomography demonstrated a prominent tracheobronchial dilation and deformation with multiple diverticularization. The most commonly used double-lumen tube or bronchial blocker could not match the distorted airways. After general anesthesia induction, a 4# laryngeal mask was inserted, through which the modified DFC was positioned in the left main bronchus with the guidance of a fiberoptic bronchoscope. The DFC balloon was inflated with 10 ml air and lung isolation was achieved without any significant air leak during one-lung or two-lung ventilation. However, the collapse of the non-dependent lung was delayed and finally achieved by low-pressure artificial pneumothorax. The surgery was successful and the patient was extubated soon after the surgery. CONCLUSIONS: Using a laryngeal mask airway with a modified double-lumen Foley catheter acted as a bronchial blocker could be an alternative method to achieve lung isolation.

Decellularized tracheal scaffold as a promising 3D scaffold for tissue engineering applications.

Tissue engineering is a science that uses the combination of scaffolds, cells, and active biomolecules to make tissue in order to restore or maintain its function and improve the damaged tissue or even an organ in the laboratory. The purpose of this research was to study the characteristics and biocompatibility of decellularized sheep tracheal scaffolds and also to investigate the differentiation of Adipose-derived stem cells (AD-MSCs) into tracheal cells. After the decellularization of sheep tracheas through the detergent-enzyme method, histological evaluations, measurement of biochemical factors, measurement of DNA amount, and photographing the ultrastructure of the samples by scanning electron microscopy (SEM), they were also evaluated mechanically. Further, In order to check the viability and adhesion of stem cells to the decellularized scaffolds, adipose mesenchymal stem cells were cultured on the scaffolds, and the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay was performed. The expression analysis of the intended genes for the differentiation of mesenchymal stem cells into tracheal cells was evaluated by the real-time PCR method. These results show that the prepared scaffolds are an ideal model for engineering applications, have high biocompatibility, and that the tracheal scaffold provides a suitable environment for the differentiation of ADMSCs. This review provides a basis for future research on tracheal decellularization scaffolds, serves as a suitable model for organ regeneration, and paves the way for their use in clinical medicine.

Efficacy of levocetirizine in isolated rat tracheal smooth muscle.

Histamine receptor-1 (H1) antagonists like levocetirizine are frequently used nowadays to treat rhinitis patients who experience rhinorrhea and sneezing. The trachea may be affected by the H1 antagonist when it is used to treat nasal symptoms, either orally or through inhalation. The purpose of this study was to ascertain in vitro effects of levocetirizine on isolated tracheal smooth muscle. As a parasympathetic mimetic, methacholine (10-6 M) causes contractions in tracheal smooth muscle, which is how we tested effectiveness of levocetirizine on isolated rat tracheal smooth muscle. We also tested the drug's impact on electrically induced tracheal smooth muscle contractions. The impact of menthol (either before or after) on the contraction brought on by 10-6 M methacholine was also investigated. According to the results, the addition of levocetirizine at concentrations of 10-5 M or more caused a slight relaxation in response to methacholine's 10-6 M contraction. Levocetirizine could prevent spike contraction brought on by electrical field stimulation (EFS). As the concentration rose, it alone had a neglect effect on the trachea's basal tension. Before menthol was applied, levocetirizine might have also inhibited the function of the cold receptor. According to this study, levocetirizine might potentially impede the parasympathetic function of the trachea. If levocetirizine was used prior to menthol addition, it also reduced the function of cold receptors.

A case report of tracheal tenting to the skin: An option to tracheostomy for post-thyroidectomy tracheomalacia.

Operating on a huge and long-standing goiter is challenging to the surgeon and anesthetist because of the possibility of tracheomalacia and collapse of the tracheal rings after extubation. We report our innovation of tenting the trachea to the skin using sutures (passed through the strap and sternocleidomastoid muscles) to prevent post-thyroidectomy tracheomalacia.

Human airway tuft cells influence the mucociliary clearance through cholinergic signalling.

BACKGROUND: Airway tuft cells, formerly called brush cells have long been described only morphologically in human airways. More recent RNAseq studies described a chemosensory cell population, which includes tuft cells, by a distinct gene transcription signature. Yet, until which level in the tracheobronchial tree in native human airway epithelium tuft cells occur and if they function as regulators of innate immunity, e.g., by regulating mucociliary clearance, remained largely elusive. METHODS: We performed immunohistochemistry, RT-PCR and immunoblotting analyses for various tuft cell markers to confirm the presence of this cell type in human tracheal samples. Immunohistochemistry was conducted to study the distribution of tuft cells along the intrapulmonary airways in humans. We assessed the influence of bitter substances and the taste transduction pathway on mucociliary clearance in mouse and human tracheal samples by measuring particle transport speed. RESULTS: Tuft cells identified by the expression of their well-established marker POU class 2 homeobox 3 (POU2F3) were present from the trachea to the bronchioles. We identified choline acetyltransferase in POU2F3 expressing cells as well as the transient receptor potential melastatin 5 (TRPM5) channel in a small population of tracheal epithelial cells with morphological appearance of tuft cells. Application of bitter substances, such as denatonium, led to an increase in mucociliary clearance in human tracheal preparations. This was dependent on activation of the TRPM5 channel and involved cholinergic and nitric oxide signalling, indicating a functional role for human tuft cells in the regulation of mucociliary clearance. CONCLUSIONS: We were able to detect tuft cells in the tracheobronchial tree down to the level of the bronchioles. Moreover, taste transduction and cholinergic signalling occur in the same cells and regulate mucociliary clearance. Thus, tuft cells are potentially involved in the regulation of innate immunity in human airways.

Application of tissue engineering techniques in tracheal repair: a bibliometric study.

Transplantation of tissue-engineered trachea is an effective treatment for long-segment tracheal injury. This technology avoids problems associated with a lack of donor resources and immune rejection, generating an artificial trachea with good biocompatibility. To our knowledge, a systematic summary of basic and clinical research on tissue-engineered trachea in the last 20 years has not been conducted. Here, we analyzed the development trends of tissue-engineered trachea research by bibliometric means and outlined the future perspectives in this field. The Web of Science portal was selected as the data source. CiteSpace, VOSviewer, and the Bibliometric Online Analysis Platform were used to analyze the number of publications, journals, countries, institutions, authors, and keywords from 475 screened studies. Between 2000 and 2023, the number of published studies on tissue-engineered trachea has been increasing. Biomaterials published the largest number of papers. The United States and China have made the largest contributions to this field. University College London published the highest number of studies, and the most productive researcher was an Italian scholar, Paolo Macchiarini. However, close collaborations between various researchers and institutions from different countries were generally lacking. Despite this, keyword analysis showed that manufacturing methods for tracheal stents, hydrogel materials, and 3D bioprinting technology are current popular research topics. Our bibliometric study will help scientists in this field gain an in-depth understanding of the current research progress and development trends to guide their future work, and researchers in related fields will benefit from the introduction to transplantation methods of tissue-engineered trachea.

We conducted a comprehensive bibliometric analysis of tissue-engineered trachea.We systematically outlined the preparation methods and current development forms of tissue-engineered trachea.We predicted future tissue-engineered trachea research trends from the perspectives of countries, institutions, researchers, and popular research topics.

Sustained pharyngeal inflation in infant airway-Flexible bronchoscopy measurements.

Sustained pharyngeal inflation (SPI) with pharyngeal oxygen flow and nasal closure (PhO2-NC) technique create positive inflation pressure in the airway. This study measured the peak inflation pressure (PIP) levels and image changes with SPI-assisted flexible bronchoscopy (SPI-FB) and compared the effects in the pharyngeal space and mid-tracheal lumen. This prospective study enrolled 20 participants aged 6 months to 3 years. Each participant underwent sequential SPI-FB of four different durations (0, 1s, 3s, and 5s) for three cycles. We used a 3.8 mm OD flexible bronchoscope to measure and analyze PIP levels, images, and lumen dimension scores. A total of 480 data were collected. The mean (SD) age and body weight were 12.0 (11.5) months and 7.8 (7.5) kg, respectively. The mean (IQR) PIPs were 4.2 (2.0), 18.5 (6.1), 30.6 (13.5), and 46.1 (25.0) cmH2O in the pharynx and 5.0 (1.6), 17.5 (6.5), 28.0 (12.3), 46.0 (28.5) cmH2O in the mid-trachea at SPI durations of 0, 1s, 3s, and 5s, respectively. The PIP levels had a positive correlation (p <0.001) with different SPI durations in both pharynx and trachea, and were nearly identical (p = 0.695, 0.787, and 0.725 at 1s, 3s, and 5s, respectively) at the same duration except the 0 s (p = 0.015). Lumen dimension scores also significantly increased with increasing SPI durations (p <0.05) in both locations. The identified lesions significantly increased as PIP levels increased (p <0.001). Conclusion: SPI-FB using PhO2-NC with durations up to 3s is safe and informative technique that provides controllable PIP, dilates airway lumens, and benefits lesion detection in the pharyngeal space and mid-tracheal lumen.

Does Cuff Design Impact Insertion and Removal Force of Tracheostomy Tubes? A Bench Model.

INTRODUCTION: Percutaneous dilatational tracheostomy is a commonly performed procedure in intensive care units. Unrecognized tracheal ring fracture has been suggested as a possible factor for tracheal stenosis. The degree of tracheal compression relates to the amount of force required to cannulate the trachea. The objective of this study was to determine the force required to insert two types of tracheostomy tubes with different cuff designs. MATERIALS AND METHODS: This bench model measured the insertion and removal force of two tracheostomy tubes; one with a barrel-shaped, high-volume, low-pressure cuff (traditional Shiley tracheostomy tube) and another with a taper-shaped, low-volume, low-pressure cuff (Shiley flexible tracheostomy tube). Three sizes of tracheostomy tubes either with a barrel- or taper-shaped cuff were tested (Jackson sizes 4, 6, and 10, corresponding to 6.5-, 7.5-, and 10-mm ISO sizes, respectively). A model representing the tissue that the tube traverses to enter the tracheal lumen was designed, and the tracheostomy tube was mounted on a universal testing machine to measure the force necessary to insert and remove the tube. RESULTS: Across all tracheostomy tubes' sizes tested, significantly less force was required to insert the Shiley flexible tracheostomy tube compared to the traditional Shiley tracheostomy tube. Significantly less force was also required to remove the flexible tracheostomy tube compared to the traditional tracheostomy tube. CONCLUSIONS: This model suggests that less force is required to insert the Shiley flexible tracheostomy tube, which could result in less tracheal compression. This may be because of the smaller taper-shaped cuff that, when deflated, occupies less volume compared to the barrel-shaped cuff. As a result, less tracheal injury may occur when using the Shiley flexible tracheostomy tube during percutaneous tracheostomy procedures.

Challenging management of an enlarged tracheoesophageal fistula in an irradiated patient.

Speech restoration after total laryngectomy may be achieved in different ways, the gold standard being tracheoesophageal puncture (TPE) with the positioning of a speech prosthesis. TPE is not immune to complications, the most common of which being leakage through or around the prosthesis. When dealing with an enlarged tracheoesophageal fistula, the management can be either conservative or surgical. In the following case report, we present a particularly challenging case, in which every conservative strategies failed and a major surgery was required to close the fistula.

Murine Intrapulmonary Tracheal Transplantation: A Model for Investigating Obliterative Airway Disease After Lung Transplantation.

Murine intrapulmonary tracheal transplantation (IPTT) is used as a model of obliterative airway disease (OAD) following lung transplantation. Initially reported by our team, this model has gained use in the study of OAD due to its high technical reproducibility and suitability for investigating immunological behaviors and therapeutic interventions. In the IPTT model, a rodent tracheal graft is directly inserted into the recipient's lung through the pleura. This model is distinct from the heterotopic tracheal transplantation (HTT) model, wherein grafts are transplanted into subcutaneous or omental sites, and from the orthotopic tracheal transplantation (OTT) model in which the donor trachea replaces the recipient's trachea. Successful implementation of the IPTT model requires advanced anesthetic and surgical skills. Anesthetic skills include endotracheal intubation of the recipient, setting appropriate ventilatory parameters, and appropriately timed extubation after recovery from anesthesia. Surgical skills are essential for precise graft placement within the lung and for ensuring effective sealing of the visceral pleura to prevent air leakage and bleeding. In general, the learning process takes approximately 2 months. In contrast to the HTT and OTT models, in the IPTT model, the allograft airway develops airway obliteration in the relevant lung microenvironment. This allows investigators to study lung-specific immunological and angiogenic processes involved in airway obliteration after lung transplantation. Furthermore, this model is also unique in that it exhibits tertiary lymphoid organs (TLOs), which are also seen in human lung allografts. TLOs are comprised of T and B cell populations and characterized by the presence of high endothelial venules that direct immune cell recruitment; therefore, they are likely to play a crucial role in graft acceptance and rejection. We conclude that the IPTT model is a useful tool for studying intrapulmonary immune and profibrotic pathways involved in the development of airway obliteration in the lung transplant allograft.

Analysis of miRNA expression in the trachea of Ri chicken infected with the highly pathogenic avian influenza H5N1 virus.

BACKGROUND: Highly pathogenic avian influenza virus (HPAIV) is considered a global threat to both human health and the poultry industry. MicroRNAs (miRNA) can modulate the immune system by affecting gene expression patterns in HPAIV-infected chickens. OBJECTIVES: To gain further insights into the role of miRNAs in immune responses against H5N1 infection, as well as the development of strategies for breeding disease-resistant chickens, we characterized miRNA expression patterns in tracheal tissues from H5N1-infected Ri chickens. METHODS: miRNAs expression was analyzed from two H5N1-infected Ri chicken lines using small RNA sequencing. The target genes of differentially expressed (DE) miRNAs were predicted using miRDB. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis were then conducted. Furthermore, using quantitative real-time polymerase chain reaction, we validated the expression levels of DE miRNAs (miR-22-3p, miR-146b-3p, miR-27b-3p, miR-128-3p, miR-2188-5p, miR-451, miR-205a, miR-203a, miR-21-3p, and miR-200a-3p) from all comparisons and their immune-related target genes. RESULTS: A total of 53 miRNAs were significantly expressed in the infection samples of the resistant compared to the susceptible line. Network analyses between the DE miRNAs and target genes revealed that DE miRNAs may regulate the expression of target genes involved in the transforming growth factor-beta, mitogen-activated protein kinase, and Toll-like receptor signaling pathways, all of which are related to influenza A virus progression. CONCLUSIONS: Collectively, our results provided novel insights into the miRNA expression patterns of tracheal tissues from H5N1-infected Ri chickens. More importantly, our findings offer insights into the relationship between miRNA and immune-related target genes and the role of miRNA in HPAIV infections in chickens.