Prone Cardiopulmonary Resuscitation (CPR) Protocol: A Single-Center Experience at Implementation and Review of Literature.

The prone position is a crucial position used in the operating rooms and the intensive care units, with its importance highly recognized during the COVID-19 pandemic in patients with acute respiratory distress syndrome (ARDS). Cardiopulmonary resuscitation (CPR) is a cardinal procedure that is indicated and performed on any eligible patient who has cardiopulmonary arrest and resultant lack of perfusion and oxygenation. When a patient has a cardiopulmonary arrest in the prone position, the options include rotating the patient supine before starting cardiopulmonary resuscitation (CPR) or beginning CPR while prone. Prone CPR has not had a widely accepted use so far. In this article, we narrate the process of protocol development and staff education at our hospital for the initiation of prone CPR and review the literature related to it. Prone CPR is an effective technique with good outcomes and involves a learning curve. Appropriate training needs to be done before implementing the protocol, and adequate quality control measures need to be set to ensure that the skill set is maintained.

Defective axonal transport of Rab7 GTPase results in dysregulated trophic signaling.

Retrograde trophic signaling of nerve growth factor (NGF) supports neuronal survival and differentiation. Dysregulated trophic signaling could lead to various neurological disorders. Charcot-Marie-Tooth type 2B (CMT2B) is one of the most common inherited peripheral neuropathies characterized by severe terminal axonal loss. Genetic analysis of human CMT2B patients has revealed four missense point mutations in Rab7, a small GTPase that regulates late endosomal/lysosomal pathways, but the exact pathological mechanism remains poorly understood. Here, we show that these Rab7 mutants dysregulated axonal transport and diminished the retrograde signaling of NGF and its TrkA receptor. We found that all CMT2B Rab7 mutants were transported significantly faster than Rab7(wt) in the anterograde direction, accompanied with an increased percentile of anterograde Rab7-vesicles within axons of rat E15.5 dorsal root ganglion (DRG) neurons. In PC12M cells, the CMT2B Rab7 mutants drastically reduced the level of surface TrkA and NGF binding, presumably by premature degradation of TrkA. On the other hand, siRNA knock-down of endogenous Rab7 led to the appearance of large TrkA puncta in enlarged Rab5-early endosomes within the cytoplasm, suggesting delayed TrkA degradation. We also show that CMT2B Rab7 mutants markedly impaired NGF-induced Erk1/2 activation and differentiation in PC12M cells. Further analysis revealed that CMT2B Rab7 mutants caused axonal degeneration in rat E15.5 DRG neurons. We propose that Rab7 mutants induce premature degradation of retrograde NGF-TrkA trophic signaling, which may potentially contribute to the CMT2B disease.