Late Endosomes Act as mRNA Translation Platforms and Sustain Mitochondria in Axons.

Local translation regulates the axonal proteome, playing an important role in neuronal wiring and axon maintenance. How axonal mRNAs are localized to specific subcellular sites for translation, however, is not understood. Here we report that RNA granules associate with endosomes along the axons of retinal ganglion cells. RNA-bearing Rab7a late endosomes also associate with ribosomes, and real-time translation imaging reveals that they are sites of local protein synthesis. We show that RNA-bearing late endosomes often pause on mitochondria and that mRNAs encoding proteins for mitochondrial function are translated on Rab7a endosomes. Disruption of Rab7a function with Rab7a mutants, including those associated with Charcot-Marie-Tooth type 2B neuropathy, markedly decreases axonal protein synthesis, impairs mitochondrial function, and compromises axonal viability. Our findings thus reveal that late endosomes interact with RNA granules, translation machinery, and mitochondria and suggest that they serve as sites for regulating the supply of nascent pro-survival proteins in axons.

Acute mediastinitis, mediastinal granuloma, and chronic fibrosing mediastinitis: A review.

Acute mediastinitis is a rare infection that carries high morbidity and mortality. They are complications seen most often with deep sternal wound infections from surgeries with median sternotomies, oropharyngeal and odontogenic infections and esophageal perforations. These conditions should be promptly recognized and treated. Mediastinal granulomas are focal, mass-like lesions commonly resulting from prior granulomatous infections. They are regarded as benign, self-resolving lesions however can cause complications by compression of adjacent mediastinal structures. Chronic fibrosing mediastinitis is a rare, diffuse fibroinflammatory process most often seen with granulomatous infections and carries a worse prognosis than mediastinal granulomas especially when adjacent mediastinal structures are compromised. In this review, we discuss the epidemiology, etiology, clinical presentation, treatment and prognosis of acute mediastinitis, mediastinal granulomas, and chronic fibrosing mediastinitis.

Evaluation of occult cervical spine fractures on radiographs and CT.

The aim of this study was to evaluate occult cervical spine fractures on radiographs and CT. We reviewed radiographs of 68 patients with cervical spine fractures at a level 1 trauma center. Twenty-six patients showed occult fractures on initial radiographs. Of seven odontoid fractures, two were diagnosed only after thinner repeat CT reconstructions. Five facet fractures were best seen on CT reconstructions. Three occult hangman's fractures were seen by CT. A C1 fracture was diagnosed on CT only. Two fractures through the C2 body were seen only by CT. Eight fractures were obscured by patient's shoulders, including five clay shoveler's fractures, a C6 facet fracture, a bilateral C6 pedicle fracture, and a C7-T1 fracture-dislocation. Odontoid, facet, and lower cervical spine fractures are most commonly occult on radiographs. CT, especially high-quality CT reconstructions for odontoid and facet fractures, can improve the diagnosis of cervical spine fracture.