Hedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. The gene encoding Smoothened (SMO), the primary effector of Hh signaling, is expressed aberrantly in human breast cancer, as well as in other cancers. In mice that express a constitutively active form of SMO that does not require Hh stimulation in mammary glands, the cells near the transgenic cells proliferate and participate in hyperplasia formation. Although SMO is a seven-transmembrane receptor like G protein-coupled receptors (GPCRs), SMO-mediated activation of the Gli family of transcription factors is not known to involve G proteins. However, data from Drosophila and mammalian cell lines indicate that SMO functions as a GPCR that couples to heterotrimeric G proteins of the pertussis toxin (PTX)-sensitive Gαi class. Using genetically modified mice, we demonstrated that SMO signaling through G proteins occurred in the mammary gland in vivo. SMO-induced stimulation of proliferation was PTX-sensitive and required Gαi2, but not Gαi1, Gαi3, or activation of Gli1 or Gli2. Our findings show that activated SMO functions as a GPCR to stimulate proliferation in vivo, a finding that may have clinical importance because most SMO-targeted agents have been selected based largely on their ability to block Gli-mediated transcription.

BackgroundAdvancements in virtual reality (VR) technology have resulted in its expansion into health care. Preliminary studies have found VR to be effective as an adjunct to anesthesia to reduce pain and anxiety for patients during upper gastrointestinal endoscopies, dental procedures and joint arthroplasties. Current standard care practice for upper extremity surgery includes a combination of regional anesthesia and intraoperative propofol sedation. Commonly, patients receive deep propofol sedation during these cases, leading to potentially avoidable risks of over-sedation, hypotension, upper airway obstruction, and apnea. The objective of this study is to evaluate the effectiveness of VR technology to promote relaxation for patients undergoing upper extremity surgery, thereby reducing intraoperative anesthetic requirements and improving the perioperative patient experience.MethodsIn this single-center, randomized controlled trial, 40 adult patients undergoing upper extremity orthopedic surgery will be randomly allocated to either intraoperative VR immersion or usual care. VR immersion is designed to provide patients with a relaxing virtual environment to alleviate intraoperative anxiety. All patients receive a peripheral nerve block prior to surgery. Patients in the intervention group will select videos or immersive environments which will be played in the VR headset during surgery. An anesthesia provider will perform their usual clinical responsibilities intraoperatively and can administer anesthetic medications if and when clinically necessary. Patients in the control arm will undergo perioperative anesthesia according to standard care practice. The primary outcome is the difference in intraoperative propofol dose between the groups. Secondary outcomes include postoperative analgesia requirements and pain scores, length of stay in the postanesthesia care unit, overall patient satisfaction and postoperative functional outcomes.DiscussionIt is unknown whether the use of VR during upper extremity surgery can reduce intraoperative anesthetic requirements, reduce perioperative complications, or improve the postoperative patient experience. A positive result from this clinical trial would add to the growing body of evidence that demonstrates the effectiveness of VR as an adjunct to anesthesia in reducing intraoperative pain and anxiety for multiple types of procedure. This could lead to a change in practice, with the introduction of a nonpharmacologic intervention potentially reducing the burden of over-sedation while still providing a satisfactory perioperative experience.Trial registrationClinicalTrials.gov, NCT03614325. Registered on 9 July 2018.

Introduction Common anesthesia practice for hand surgery combines a preoperative regional anesthetic and intraoperative monitored anesthesia care (MAC). Despite adequate regional anesthesia, patients may receive doses of intraoperative sedatives which can result in oversedation and potentially avoidable complications. VR could prove to be a valuable tool for patients and providers by distracting the mind from processing noxious stimuli resulting in minimized sedative use and reduced risk of oversedation without negatively impacting patient satisfaction. Our hypothesis was that intraoperative VR use reduces sedative dosing during elective hand surgery without detracting from patient satisfaction as compared to a usual care control. Methods Forty adults undergoing hand surgery were randomized to receive either intraoperative VR in addition to MAC, or usual MAC. Patients in both groups received preoperative regional anesthesia at provider discretion. Intraoperatively, the VR group viewed programming of their choice via a head-mounted display. The primary outcome was intraoperative propofol dose per hour (mg · hr-1). Secondary outcomes included patient reported pain and anxiety, overall satisfaction, functional outcome, and post anesthesia care unit (PACU) length of stay (LOS). Results Of the 40 enrolled patients, 34 completed the perioperative portion of the trial. VR group patients received significantly less propofol per hour than the control group (Mean (±SD): 125.3 (±296.0) vs 750.6 (±334.6) mg · hr-1, p<0.001). There were no significant differences between groups in patient reported overall satisfaction, (0–100 scale, Median (IQR) 92 (77–100) vs 100 (100–100), VR vs control, p = 0.087). There were no significant differences between groups in PACU pain scores, perioperative opioid analgesic dose, or in postoperative functional outcome. PACU LOS was significantly decreased in the VR group (53.0 (43.0–72.0) vs 75.0 (57.5–89.0) min, p = 0.018). Conclusion VR immersion during hand surgery led to significant reductions in intraoperative propofol dose and PACU LOS without negatively impacting key patient reported outcomes.

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