[Double aortic arch and aortotracheal fistula as cause of fatal massive bleeding: a rare and dangerous association]. / Doble arco aórtico y fistula aortotraqueal como causa de hemorragia masiva fatal: una asociación rara y peligrosa.

Vascular rings are unusual congenital malformations. Among them, double aortic arch (DAA) is often difficult to diagnose due to its low incidence of symptoms. DAA can be associated with tracheal or esophageal compression and, in severe cases, could require tracheal intubation or chronic use of a nasogastric tube. This scenario favors the development of aortotracheal fistulas (ATF) or aortoe-sophageal fistulas (AEF). OBJECTIVE: To present a clinical case with an unusual association of DAA with ATF and to reinforce the importance of maintaining high diagnostic suspicion in patients with massive aerodigestive bleeding without an obvious source. CLINICAL CASE: A 32-week preterm newborn who required prolonged mechanical ventilation and presented intermittent episodes of massive oropharyngeal bleeding with hemodynamic compromise associated with lower airway obstruction without pulmonary hemorrhage. The patient underwent upper endoscopy and exploratory laparotomy without evidence of bleeding. Flexible nasopharyngolaryngoscopy and direct laryngoscopy also showed no abnormalities. A CT angiography showed complete DAA with indentation of the left dominant arch over the trachea, without severe stenosis or evidence of a fistula. AEF was suspected, so exploratory surgery was considered. However, the patient died before surgery due to a massive pulmonary hemorrhage. The autopsy revealed the presence of ATF. CONCLUSIONS: In patients with massive aerodigestive bleeding without an obvious source, the presence of DAA and possible AEF/ ATF should be considered. Imaging studies have a poor performance for this diagnosis, so surgery should be considered for diagnosis and treatment in these patients.

Subcellular positioning during cell division and cell plate formation in maize.

Introduction: During proliferative plant cell division, the new cell wall, called the cell plate, is first built in the middle of the cell and then expands outward to complete cytokinesis. This dynamic process requires coordinated movement and arrangement of the cytoskeleton and organelles. Methods: Here we use live-cell markers to track the dynamic reorganization of microtubules, nuclei, endoplasmic reticulum, and endomembrane compartments during division and the formation of the cell plate in maize leaf epidermal cells. Results: The microtubule plus-end localized protein END BINDING1 (EB1) highlighted increasing microtubule dynamicity during mitosis to support rapid changes in microtubule structures. The localization of the cell-plate specific syntaxin KNOLLE, several RAB-GTPases, as well as two plasma membrane localized proteins was assessed after treatment with the cytokinesis-specific callose-deposition inhibitor Endosidin7 (ES7) and the microtubule-disrupting herbicide chlorpropham (CIPC). While ES7 caused cell plate defects in Arabidopsis thaliana, it did not alter callose accumulation, or disrupt cell plate formation in maize. In contrast, CIPC treatment of maize epidermal cells occasionally produced irregular cell plates that split or fragmented, but did not otherwise disrupt the accumulation of cell-plate localized proteins. Discussion: Together, these markers provide a robust suite of tools to examine subcellular trafficking and organellar organization during mitosis and cell plate formation in maize.