This study aimed to elucidate the effect of tryptophan (Trp) on gut hormone secretion as well as the roles of the calcium-sensing receptor (CaSR) and its downstream signaling pathway in gut hormone secretion by assessing swine duodenal perfusion in vitro. Swine duodenum was perfused with Krebs-Henseleit buffer as a basal solution. Various concentrations (0, 10, and 20 mM) of Trp were applied to investigate its effect on gut hormone secretion. A CaSR antagonist was used to detect the involvement of CaSR and its signal molecules. The 20 mM Trp concentration promoted the secretion of cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP), elevated the mRNA level of CaSR, and upregulated the protein levels of CaSR, protein kinase C (PKC), and inositol trisphosphate receptor (IP3R). However, NPS 2143, an inhibitor of CaSR, attenuated the CCK and GIP release, reduced the mRNA level of CaSR, and decreased the protein levels of CaSR, PKC, and IP3R with 20 mM Trp perfusion. The results indicate that CCK and GIP secretion can be induced by Trp in swine duodenum in vitro, and the effect is mediated by CaSR and its downstream signal molecules PKC and IP3R.
Cholecystokinin ; Duodenum ; Gastric Inhibitory Polypeptide ; In Vitro Techniques ; Inositol ; Perfusion ; Protein Kinase C ; Receptors, Calcium-Sensing ; RNA, Messenger ; Swine ; Tryptophan

Objective:To investigate the related factors that affect the timing and prognosis of early tracheostomy in patients with multiple rib fractures.Methods:A retrospective case series study was conducted on medical data of 222 patients with multiple rib fractures who underwent tracheostomy in Affiliated Hospital of Yangzhou University from February 2013 to October 2019，including 160 males and 66 females，with the age of 18 to 85 years ［（49.5 ± 16.3）years］. According to the practice management guidelines for tracheostomy timing and the use of propensity score matching technology，there were 118 patients with tracheostomy within 7 days of tracheal intubation （early group） and 104 patients with tracheostomy after 7 days of tracheal intubation （late group） before matching，and there were 87 patients in early group and 87 patients in late group after matching. Data were compared between groups including the gender，age，underlying disease，injury severity score （ISS），Glasgow coma score （GCS），number of fractured ribs，total number of rib fractures （NTRF），first rib fracture，flail chest，traumatic brain injury，combined injuries （spine，maxillofacial，sternum），acute respiratory distress syndrome （ARDS），volume fraction of pulmonary contusion（VPC），blood lactic acid （within 24 hours of admission），hemothorax，pneumothorax，mechanical ventilation time，duration of tracheostomy，time from tracheal intubation to incision，length of hospital stay，length of stay in ICU，closed thoracic drainage，number of fiberoptic bronchoscopy，multi-drug resistant bacteria infection，ventilator-associated pneumonia，antibiotic use time，duration of sedative and analgesic drugs used and 28-day mortality. The multivariate Logistic regression analysis was used to predict independent risk factors for early tracheostomy. The Pearson method was used to compare the relationship between multiple factors. The receiver operating characteristic （ROC） curve was used to predict indicators that affect the prognosis of patients with early tracheostomy，and calculate the best cut-off value. The Kaplan-Meier single factor and COX multivariate survival were used to analyze the relevant factors affecting the 28-day mortality of patients.Results:（1） In early group，the NTRF，ARDS and VPC were higher than those in late group，and the time from tracheal intubation to incision and 28-day mortality rate were lower than those in late group （ P < 0.05），while the two groups showed no significant differences in the gender，age，underlying diseases and ISS （ P > 0.05）. （2） The multivariate Logistic regression analysis showed that there was statistical significance in NTRF （ OR = 1.775，95% CI 1.439-2.188），ARDS（ OR = 3.740，95% CI 1.441-9.711），VPC （ OR = 1.087，95% CI 1.052-1.124） （ P < 0.05）； the Pearson method analysis showed a significant correlation between VPC and NTRF （ r = 0.369， P < 0.05） and a low degree of correlation between ARDS and VPC （ r = 0.179， P < 0.05），but there was no significant correlation between ARDS and NTRF （ r = 0.132， P > 0.05）. （3） The ROC curve analysis showed that the area under the curve （AUC） of the VPC and NTRF ［AUC = 0.832 （95% CI 0.770-0.893），AUC = 0.804 （95% CI 0.740-0.868）］ were significantly higher than those of the number of rib fractures ［AUC = 0.437（95% CI 0.352-0.523），GCS ［AUC = 0.519 （95% CI 0.432-0.605）］ and ISS ［AUC = 0.484 （95% CI 0.398-0.571）］ （ P < 0.05）. After calculating the Yorden index，the best cut-off value for VPC was 23.9，and the best cut-off value for NTRF was 8.5. （4） The Kaplan-Meier single factor and multivariate COX model survival analysis showed that the 28-day survival ratio of patients with early tracheostomy was significantly better than that of late tracheostomy （ P < 0.05）. Conclusions:The NTRF，ADRS and VPC are independent risk factors for the timing and prognosis of early tracheostomy. There is a significant correlation between VPC and NTRF. The VPC ≥ 23.9% and or NTRF ≥ 8.5 can be used to predict early tracheostomy in patients with multiple rib fractures. Early tracheostomy may benefit the 28-day survival of patients with multiple rib fractures.