Tracheal tube fusion in Drosophila involves release of extracellular vesicles from multivesicular bodies

Extracellular vesicles (EVs) comprise diverse types of cell-released membranous structures that are thought to play important roles in intercellular communication. While the formation and functions of EVs have been investigated extensively in cultured cells, studies of EVs in vivo have remained scarce. We report here that EVs are present in the developing lumen of tracheal tubes in Drosophila embryos. We defined two distinct EV subpopulations, one of which contains the Munc13-4 homologue Staccato (Stac) and is spatially and temporally associated with tracheal tube fusion (anastomosis) events. The formation of Stac-positive luminal EVs depends on the tracheal tip-cell-specific GTPase Arl3, which is also required for the formation of Stac-positive multivesicular bodies, suggesting that Stac-EVs derive from fusion of Stac-MVBs with the luminal membrane in tip cells during anastomosis formation. The GTPases Rab27 and Rab35 cooperate downstream of Arl3 to promote Stac-MVB formation and tube fusion. We propose that Stac-MVBs act as membrane reservoirs that facilitate tracheal lumen fusion in a process regulated by Arl3, Rab27, Rab35, and Stac/Munc13-4.

Tracheoarterial fistula as a complication of prolonged tracheostomy

The article presents a clinical case of a rare and severe complication of prolonged tracheostomy in the form of fistula formation between tracheal lumen and brachiocephalic artery and the development of massive bleeding from it. The patient’s treatment was urgent and successful. Operative intervention was performed with subsequent allografting of brachiocephalic trunk (vascular prosthesis Vascutek 8 mm was used) and the anastomosis was created using a continuous suture technique. The patient was discharged home in a satisfactory condition on the 17th post-operative day.

Tracheal tube fusion in Drosophila involves release of luminal exosomes from multivesicular bodies

Fusion of endothelial or epithelial tubes is essential for the development of organs like the vertebrate vasculature or the insect tracheal system, but the mechanisms underlying the formation of tubular connections (anastomoses) are not well understood. Tracheal tube fusion in Drosophila is mediated by tip cells that transform into lumenized toroids to connect adjacent tubes. This process depends on the Munc13-4 orthologue Staccato (Stac), which localizes to tip-cell-specific lysosome-related organelles (LROs). We show that tracheal LROs display features of multivesicular bodies (MVBs) and that the tracheal lumen contains membranous extracellular vesicles (EVs), a subset of which carries Stac/Munc13-4 and is associated with tracheal anastomosis sites. The presence of LROs and luminal Stac-EVs depends on the tip-cell-specific GTPase Arl3, suggesting that Stac-EVs derive from fusion of MVBs with the luminal membrane in tip cells during anastomosis formation. The GTPases Rab27 and Rab35 cooperate downstream of Arl3 to promote Stac-MVB formation and tube fusion. We propose that Stac-MVBs act as membrane reservoirs that facilitate lumen fusion in tip cells, in a process regulated by Arl3, Rab27, Rab35, and Stac/Munc13-4.

Aortopexy for Tracheomalacia Via Partial Sternotomy

Tracheomalacia (TM) is a disease that causes the airway obstruction of the tracheal lumen as a result of the structural disorder of the tracheal cartilage. We present a 4-month-old patient who developed ventilator depended TM after repair of esophageal atresia with tracheoesophageal fistula. Aortopexy and intraoperative flexible bronchoscopy were first performed via partial sternotomy in Turkey for this patient. He was weaned from ventilatory support and extubated at the first and discharged at the 8th post-operative day. Partial sternotomy is performed in the supine position, thus it allows for intraoperative flexible bronchoscopy permitting to check for the adequacy of the aortopexy.

The first experience of tracheal recanalization by tumor resection with Nd-YAG-laser

Actuality. Tracheal cancer is a rare disease which amounts up to 0.2% of the total number of cancers. Currently, there is an increase in the number of patients with impaired tracheal patency. Endoscopic procedures are most commonly used to restore and maintain the tracheal lumen. The key treatment for primary cancer is a surgical one; however, due to late diagnostics, the tumor is often inoperable. Chemotherapy for tracheal cancer is ineffective, and practically is not used. At present, endoscopic tracheal recanalization with laser vaporization is a method of choice in patients with inoperable tracheal tumors.Objective: to improve outcomes in patients with inoperable primary tracheal cancer using Nd-YAG laser either as the fi rst component of staged treatment strategy, or as the fi nal volume treatment.Methods. Patient K., 75 years old, was admitted to the hospital with complaints of dyspnea at rest, weakness and hemoptysis. As anamnesis showed, the patient had noticed a deterioration in her breathing during the last 6 months. CT scan revealed a volumetric formation (tumor) of the cervicothoracic trachea (8.0 cm above the bifurcation) with 90% stenosing in the lumen. When performing tracheobronchoscopy in the cervicothoracic trachea, a broad-based lumpy tumor, 5 cm long, stenosing the tracheal lumen by 2/3 was found on the posterior wall. Morphological examination of biopsy material revealed adenocystic carcinoma.Results. The performed endoscopic examination with neodymium YAG laser recanalization demonstrated the advantage of this technique in patients with inoperable tracheal tumors.Conclusion. Endoscopic recanalization of the trachea with neodymium YAG laser has been proven to be effective in patients with inoperable tracheal cancer. It improves their quality of life as well.

The Effects of Mycophenolate on the Formation of Granulation Tissue Post-operatively in Canine Tracheal Stent Patients (2014–2020)

Objectives: To determine if mycophenolate mofetil reduces the incidence and severity of granulation tissue in-growth in canine tracheal stent patients.Study design: Randomized clinical trial.Animals: 111 dogs from the hospital population.Methods: Client-owned dogs that received an endoluminal self-expanding tracheal stent for canine tracheal collapse between 2014 and 2020 were randomly assigned into one of two treatment groups. Control group medication protocol consisted of prednisone 0.5 mg/kg PO BID/SID/EOD × 30 days, hydrocodone 0.25 mg/kg PO TID × 30 days, and cefovecin 8 mg/kg SQ post-placement. Mycophenolate group medication protocol was identical to the control group medication protocol with the addition of mycophenolate mofetil 10 mg/kg PO BID × 30 days, SID for life. Recheck tracheoscopy was performed at 1, 3, and 6 months post-stent placement. Presence and severity of granulation tissue were determined by tracheoscopy and were recorded as a percentage of tracheal lumen obstruction by blinded evaluators (none present, <25%, >25–50%, and >50%).Results: At none of the three time points was there a statistically significant difference in grade between controls and those receiving mycophenolate (p = 0.467, p = 0.330, and p = 0.410).Conclusions and Clinical Significance: Our results suggest that mycophenolate can be safely given to these patients but do not support that its administration will reduce the incidence and severity of granulation tissue. Although a difference was observed in the severity of granulation tissue between the two groups, loss to follow-up may have influenced conclusions. A larger study would be warranted to further evaluate the effect of mycophenolate on the development of granulation tissue.

NEODYMIUM LASER IN LARINGOTRACHEOSTENOSIS TREATMENT AFTER TRACHEOSTOMY IN CHILDREN

Objective. To evaluate the effect of neodymium laser application for successful decannulation in infants with a congenital and acquired tracheal stenosis and tracheostomy. Methods. 6 children were being treated in the 1^st City Clinical Hospital of Minsk in 2011-2014. All children underwent tracheostomy with a prolonged tracheal intubation and subsequent development of tracheostenosis. The children were examined using X-ray, esophagogastroscopy (PentaxEG-16K10), and bronchoscopy (Olympus MAF TYPE GM). Tracheal stenosis was treated using a medical multifunctional laser complex Multiline (“Linline Medical systems” Ltd, Belarus) equipped with a high-energy neodymium laser emitter. Children with excessive growth of granulations in thelumenof thetrachea underwent vaporization of granulations by means of a bulbous probe with a neodymium laser emitter (wavelength of 1340 nm, power: 15 W, 2 sec. exposure). In cicatricial tracheal stenosis, incisions were made with a laser scalpel (the wavelength of 1064 nm, power of 20 W). Results. Effective decannulation was observed in 5 children, including 4 children who underwent3-5 treatment sessions. In 1 child with the congenital subglottic larynx stenosis, to perform the decannulation became possible after 2 years and 24 sessions of laser recanalizationofstenosis and ablation of granulations. One child, after 9 treatment sessions, dropped out of observation, the result has not been defined. Conclusion. Tracheostomy in children promotes the formation of granulations in the tracheal lumen with the formation of stenosis, which subsequently hinders a successful decannulation. The neodymium laser application with the endoscopic access provides the visual direct approach to the focus of impact with the aim of laser-induced vaporization of soft tissues and recanalization of the trachealmass in children with short tracheal stenosis leads to successful decannulation. What this paper adds Firstly the neodymium laser for the treatment of congenital and acquired tracheal stenosis in children after tracheotomy has been used. The method has been developed for restoring the tracheal lumen by laser-inducedvaporization of excessive tracheal granulation and making scalpel incisions in the scar area. It is shown the neodymium laser application with the endoscopic access provides the visual direct approach to the focus of impact. Laser-induced vaporization of soft tissues and recanalization of the tracheal lumen in children with short tracheal stenosis leads to successful decannulation.

Tracheal Adenocarcinoma in a Cat

Background: Primary tracheal adenocarcinoma is a rare neoplasm in cats. The clinical signs often are indicative of upper airway obstruction accompanied with dyspnea, stridor, wheezing, exercise intolerance, and cough. The severity of the clinical signs is related to the size of the mass and consequently, the proportion of the tracheal lumen that is obstructed. The diagnosis is made using thoracic radiography and tracheobronchoscopy by collecting fragments for histopathological analysis and removing the mass. The present study aimed to report the case of a cat with tracheal adenocarcinoma.Case: A 17-year-old Persian female cat presented with clinical signs of dyspnea and progressive weight loss. Emergency therapy was started with bronchodilators, antibiotics, and corticosteroids, but there was no response to treatment. Complementary blood and imaging tests were performed. Thoracic radiography revealed soft tissue opacity overlying the dorsal trachea from the third to the fourth rib, bronchial pattern, and pulmonary hyperinflation. Tracheoscopy showed an irregular intraluminal thoracic trachea mass, occluded by approximately 95% of the airway lumen. The mass was biopsied multiple times with endoscopic cup biopsy forceps, followed by removal of approximately 50% of the mass lesion with an endoscopic wire snare. The patient was in intensive care, and since her clinical condition worsened 48 h after the endoscopic procedure, euthanasia was performed. Necropsy revealed a remanescent mass located in the trachea lumen 8 x 3 mm and a nodule in the right caudal pulmonary lobe with 8 mm of diameter . Histological examination showed epitelian cuboidal neoplastic cells with acinar patterns. Only a few mitosis and moderate anysocitosis were observed. The final diagnosis was primary tracheal adenocarcinoma with pulmonary metastasis.Discussion: The initial oxygen therapy associated with bronchodilators and antibiotics can be explained by the history of asthma. Tracheal tumors in cats are considered to be rare, which makes the diagnosis challenging. The suspicion of tracheal neoplasia was only raised after radiographic examination, but it was not possible to state whether it was intra- or extratracheal. The bronchial pattern reported herein can be observed both in inflammatory diseases such as asthma and bronchitis as well as aging-related diseases in animals. Pulmonary hyperinflation, with a caudal displacement of the diaphragm, is seen in bronchial diseases and in cases of tracheal neoplasms, with the latter justified by the retention of air in the pulmonary lobes. Dehydration and weight loss in the animal are justified by severe dyspnea, which makes it difficult to consume food and water. The tracheoscopy procedure was essential to confirm intraluminal tracheal neoplasia with almost complete lumen obstruction. An attempt was made to remove the neoplasms with polypectomy endoscopic forceps. However, because 95% of the trachea was obstructed, the manipulation led to local edema and bleeding, which promoted complete obstruction of the air passage to the lungs. The obstruction impaired the patient's oxygenation, justifying procedure suspension. The instability and worsening of the clinical picture persisted in the subsequent days, which prevented further intervention, culminating in the animal's euthanasia. Adenocarcinoma, in the present case, was in the advanced stage, evidenced by the presence of pulmonary metastasis. Dyspnea severity was related to neoplasm size, proportion of tracheal lumen obstruction, and presence of pulmonary metastasis. The tumor size associated with the presence of metastasis was a determining factor for the classification of neoplasia in the advanced stage, making more invasive interventions impossible and worsening the patient prognosis.

Assessment of continuous ventilation during tracheal dilatation using a novel, non-occlusive balloon in an ovine model

Introduction: Balloon dilatation is frequently used in the management of tracheal stenosis. Traditional dilatation balloons cause complete occlusion of the tracheal lumen when deployed, limiting duration of dilatation due to development of hypoxia and increasing the risk of barotrauma. We assessed a novel, non occlusive airway dilatation balloon to determine whether it would allow continuous oxygenation and ventilation. Methods: This was a prospective, descriptive, interventional trial undertaken in the animal research laboratory using a healthy ovine model. Eight anaesthetised adult Dohne Merino sheep underwent placement and inflation of the study device in the trachea via an endotracheal tube with multiport adaptor. Airway pressures, ventilatory parameters, end-tidal capnography and peripheral oxygen saturations were monitored continuously and measured before insertion, before inflation and during balloon inflation. Results: All subjects could be ventilated continuously. At no time during balloon deployment and inflation was there a loss of capnograph waveform or peripheral arterial desaturation. While there was a slight trend to increased pressures and decreased tidal volumes after balloon insertion and inflation, these changes were not clinically relevant. The median (range) at each time point were tidal volume of 565 (370–780), 560 (330–830) and 550 (320–830) ml, peak airway pressure of 11(9–22), 14 (11–17) and 14 (13–17) cmH2O, and plateau pressure of 9 (7–17), 11 (9–14) and 11 (9–14) cmH2O respectively. Conclusion: Continuous oxygenation and ventilation through the study device during tracheal dilatation is possible, effective and practical.