Objective To explore the histomorphology and related indicators in a rat model of skeletal muscle injury in an artificial experimental chamber as special environment in Northwest China to stimulate a hot and dry desert environment in order to screen the evaluation indicators of skeletal muscle injury in a hot and dry environment.Methods Eighteen male SD rats (8 weeks old)were randomly divided into blank control group (room temperature,free movement),room temperature exercise group,and hot and dry exercise group,with 6 rats in each group.After the rats were subjected to adaptation training for 3 d (a 3-D exercise treadmill,speed:16 m/min,slope:-16°,time:5～10 min),the rats in the 2 exercise groups were subjected to a treadmill once per day at a speed of 19.3 m/min and a slope of-16°till the end of exhaustion,and those in the hot and dry exercise group were housed in an artificial experimental chamber at a temperature of (40±1 )℃,a humidity of (10±2)％.After 6 d of continuous exercise,the rat soleus muscle tissue was taken to observe the pathological changes,and the serum samples were detected for skeletal muscle injury markers,inflammatory factors,oxidative stress related factors,hormones and other related indicators. Results When compared with the blank control group and the room temperature exercise group,the hot and dry exercise group had significantly higher concentrations of creatine kinase (CK),creatine kinase isoenzyme (CK-MB)and muscle-specific creatine kinase (CK-MM)(P<0.05 ),elevated contents of TNF-α,IL-1βand IL-6 (P<0.05),raised malondialdehyde (MDA)content and lower superoxide dismutase (SOD)activity (P<0.05 ),lower testosterone (T)but higher corticosterone (Cort)levels and thus lower testosterone/corticosterone (T/Cort)ratio (P<0.05 ).The markers of skeletal muscle injury,CK,CK-MB and CK-MM were positively correlated with the pro-inflammatory cytokines,TNF-α,IL-1βand IL-6 (P<0.05),positively with the antioxidant indicator MDA but negatively with SOD (P<0.05 ),and positively correlated with Cort level and negatively with T level and T/Cort ratio (P<0.05).Conclusion A stable rat model of skeletal muscle injury in a hot and dry desert environment is successfully constructed.The severity of skeletal muscle injury is greater in rats in a hot and dry desert environment than those in a normal temperature environment. TNF-α and IL-1β are found to be indirect indicators to evaluate skeletal muscle injury in the environment.

Objective:To investigate the types, incidences, and clinical characteristics of shock in polytrauma patients at different stages after polytrauma.Methods:A retrospective study was conducted on polytrauma patients admitted to multiple trauma centers from June 2020 to December 2021. The inclusion criteria were patients >18 years old and treated due to polytrauma. Exclusion criteria included an admission time of more than 48 h after trauma, a history of malignancy, or metabolic, consumptive, and immunological diseases. The early stage was defined as the period of ≤48 h after polytrauma, and the middle stage was defined as the period between 48 h and 14 days. The patient’s medical history, clinical manifestations, laboratory tests, imaging examination, injury severity score (ISS), and Glasgow coma scale (GCS) were collected. The types, incidences, and clinical characteristics of shock in different stages after polytrauma were analyzed, according to the diagnostic criteria of each type of shock. The differences between the groups were compared by Student’s t test, χ2 test or Mann-Whitney U test. Results:The incidence of the early and middle stage shock after polytrauma were 73.1% and 36.4%, respectively, with statistically significant difference between stages ( P<0.01). There were significant differences in the incidence of hypovolemic shock (83.6% vs. 28.4%), distributed shock (13.7% vs. 80.9%) and cardiogenic shock (3.5% vs. 6.6%) between stages (all P<0.05). The incidence of obstructive shock (8.4% vs. 9.7%, P>0.05) was similar between stages. The incidence of undifferentiated shock was 1.6% and 1.2%, respectively. There were 9.5% patients with multifactorial shock in the early stage and 14.4% in the middle stage. Totally 7 combinations of multifactorial shock were found in different stages after polytrauma. In the early stage, the combination of HS and DS accounted the highest ratio (42.3%) and followed by HS and OS for 28.8%. In the middle stage, the combination of HS and DS was the most common (48.6%) and followed by DS and OS (24.3%). Conclusions:The incidence of shock in polytrauma patients is high. Different types of shock can occur simultaneously or sequentially. Therefore a comprehensive resuscitation strategy is significant to improve the success rate of treatment.

Objective: To evaluate the clinical efficacy of positioning guide templates for maxillary wholly impacted supernumerary teeth to provide technological solutions for clinical applications. Methods : After approval by the hospital ethics committee and informed consent given by the patients. Data from 136 patients with maxillary wholly impacted supernumerary teeth from January 2016 to April 2022 were analyzed retrospectively. The patients were divided into two groups according to the usage of the positioning guide template. The experimental group included patients using the positioning guide template (71 cases), and the control group did not use the positioning guide template (65 cases). The operation time and complications were statistically analyzed to evaluate the clinical efficacy after surgery. Results : All operations were successfully completed. The average operation time in the experimental group was (21.5 ± 3.4) min, significantly shorter than that in the control group (27.2 ± 4.9) min. There were statistically significant differences between the experimental and control groups (t = 7.599, P<0.001). One week after the operation, there were no complications in the experimental group, and there were 2 cases of adjacent tooth injury and 3 cases of gingival numbness in the control group. Conclusion A digital positioning guide template can effectively shorten the time of maxillary wholly impacted supernumerary teeth extraction and is an effective means to assist clinical maxillary wholly impacted supernumerary teeth extraction.