The vertebrate olfactory epithelium (OE) is known for its ability to renew itself throughout life as well as to reconstitute after injury. Although this remarkable capacity demonstrates the persistence of stem cells and multipotent progenitor cells, their nature in the OE remains undefined and controversial, as both horizontal basal cells (HBCs) and globose basal cells (GBCs) have features in common with each other and with stem cells in other tissues. Here, we investigate whether some among the population of GBCs satisfy a key feature of stem cells, i.e., mitotic quiescence with retention of thymidine analogue label and activation by injury. Accordingly, we demonstrate that some GBCs express p27Kip1, a member of the Kip/Cip family of cyclin-dependent kinase inhibitors. In addition, some GBCs retain bromodeoxyuridine or ethynyldeoxyuridine for an extended period when the pulse is administered in neonates followed by a 1-month chase. Their identity as GBCs was confirmed by electron microscopy. All spared GBCs express Ki-67 in the methyl bromide (MeBr)-lesioned OE initially after lesion, indicating that the label-retaining (LR) GBCs are activated in response to injury. LR-GBCs reappear during the acute recovery period following MeBr exposure, as demonstrated with 2- or 4-week chase periods after labeling. Taken together, our data demonstrate the existence of LR-GBCs that are seemingly activated in response to epithelial injury and then re-established after the initial phase of recovery is completed. In this regard, some among the GBCs satisfy a common criterion for functioning like stem cells.
The vertebrate olfactory epithelium (OE) is known for its ability to renew itself throughout life as well as to reconstitute after injury. Although this remarkable capacity demonstrates the persistence of stem cells and multipotent progenitor cells, their nature in the OE remains undefined and controversial, as both horizontal basal cells (HBCs) and globose basal cells (GBCs) have features in common with each other and with stem cells in other tissues. Here, we investigate whether some among the population of GBCs satisfy a key feature of stem cells, i.e., mitotic quiescence with retention of thymidine analogue label and activation by injury. Accordingly, we demonstrate that some GBCs express p27Kip1, a member of the Kip/Cip family of cyclin‐dependent kinase inhibitors. In addition, some GBCs retain bromodeoxyuridine or ethynyldeoxyuridine for an extended period when the pulse is administered in neonates followed by a 1‐month chase. Their identity as GBCs was confirmed by electron microscopy. All spared GBCs express Ki‐67 in the methyl bromide (MeBr)‐lesioned OE initially after lesion, indicating that the label‐retaining (LR) GBCs are activated in response to injury. LR‐GBCs reappear during the acute recovery period following MeBr exposure, as demonstrated with 2‐ or 4‐week chase periods after labeling. Taken together, our data demonstrate the existence of LR‐GBCs that are seemingly activated in response to epithelial injury and then re‐established after the initial phase of recovery is completed. In this regard, some among the GBCs satisfy a common criterion for functioning like stem cells. J. Comp. Neurol. 522:731–749, 2014. © 2013 Wiley Periodicals, Inc.
A case of a 31-year-old male who developed profound sensorineural hearing loss following a heroin overdose is presented. The patient subsequently had a full recovery of his hearing. Other cases of this rare phenomenon are reviewed and management options are discussed.
The trigeminocardiac reflex can be provoked by a number of head and neck and skull base procedures including parotidectomy and posterior maxillectomy. Surgeons and anesthesiologists should be wary of inciting the reflex during manipulation of trigeminal branches. Careful dissection for prevention and early intervention with stimulus removal and anticholinergic use as needed are paramount to ensure good outcomes.
Nasopharyngeal branchial cysts (NBCs) have been discussed in the literature in only a limited number of publications. Differing from Tornwaldt cysts, NBCs present laterally and arise from the fossa of Rosenmuller and may track superiorly within the bony confines of the Eustachian tube. Initially patients are asymptomatic but may present with aural fullness, unilateral conductive hearing loss, and serous otitis media as the cyst mass grows. Two of our three patients had the lesion incidentally identified at the time of assessment for another diagnosis. In this case series, imaging characteristics and response to treatment are reviewed. A literature search was performed to summarize the management options for this entity.
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