RESUMO
Once thought of as an immune-privileged site, we now know that the nervous system communicates in a bidirectional manner with the immune system via the neuroimmune axis. Neuropeptides constitute a component of this axis, playing critical roles in the brain and periphery. The function of salivary neuropeptides in the acute stress response is not well understood. The purpose of this study is to investigate salivary neuropeptide levels during acute stress. Salivary samples were collected from fire recruits engaged in a stress training exercise previously shown to induce acute stress, at three separate timepoints during the exercise and levels of oxytocin, neurotensin, Substance P, α-MSH, and ß-Endorphin were measured using the Human Neuropeptide 5-Plex Custom Assay Eve Technologies. All neuropeptides increased throughout the acute stress simulation and during the recovery phase. Exploratory factor analysis (EFA) identified one factor contributing to baseline values across five neuropeptides and Pairwise Pearson Correlation Coefficient analysis showed positive correlations >0.9 for almost all neuropeptide combinations at the pre-stress timepoint. Further analysis identified negative and positive correlations between past-life trauma and self-assessed hardiness, respectively. Calculated neuropeptide scores showed an overall positive correlation to self-assessed hardiness. Altogether, our results suggest that salivary neuropeptides increase synchronously during acute stress and higher levels correlate with an increase in self-assessed hardiness. Further study is required to determine if interventions designed to enhance neuropeptide activity can increase stress resilience, especially in high-stress occupations such as firefighting.
RESUMO
BACKGROUND: Recent evidence suggests that there may be an increased risk of infection for patients undergoing a corticosteroid injection before, during, or after knee arthroscopy. PURPOSE: To systematically review the literature to evaluate the risk of postoperative infection in patients undergoing intra-articular corticosteroid injections (CSI) before, during, or after knee arthroscopy. STUDY DESIGN: Systematic review; Level of evidence, 3. METHODS: A systematic review was performed by searching the PubMed, Cochrane Library, and Embase databases to identify studies that evaluated the rate of postoperative infection in patients undergoing knee arthroscopy who received an intra-articular CSI during the perioperative period. The search phrase used was "knee AND arthroscopy AND injection AND (infection OR revision)." A subanalysis was also performed to analyze infection rates based on the timing of the corticosteroid injection in relation to arthroscopy. RESULTS: Four studies met the inclusion criteria, representing 11,925 patients undergoing knee arthroscopy with an intra-articular CSI administered during the perioperative period (mean follow-up, 5.3 months) and 247,329 patients without a corticosteroid injection during the perioperative period (mean follow-up, 5.9 months). Patients who received an injection experienced a statistically significantly higher rate of postoperative infection (2.2%) when compared with patients who did not receive an injection (1.1%; P < .001). When analyzed by the timing of the injection, patients receiving an injection preoperatively or intraoperatively experienced a statistically significantly higher rate of postoperative infection (3% and 2.6%, respectively) when compared with patients receiving an injection postoperatively (1.4%; P = .001 for both). CONCLUSION: Patients undergoing knee arthroscopy who receive an intra-articular CSI during the perioperative period can be expected to experience significantly higher postoperative infection rates when compared with patients not receiving an injection. Furthermore, patients receiving a corticosteroid injection pre- or intraoperatively may experience significantly higher rates of postoperative infection when compared with patients receiving an injection postoperatively.