"3+2" educational model was performed in our clinical medical college as a reformation based on traditional "4+1" model.After 5 years teaching practice,it obtained some good results as we prospected,however,there still exists some problems.This article analyzes the problems around the aspect of the teachers,the students,the teaching administration and arrangements,and proposes the corresponded measure to improve it.

Objective:To investigate the characteristics of bacterial community in upper gastrointestinal tumors.Methods:The study population was patients with upper gastrointestinal tumors (esophageal cancer and gastric cancer). Gastroscopy was performed on the enrolled patients ( n=17), and the specimens were taken from the tumor sites. At the same time, non-tumor tissues more than 4 cm away from the tumor tissues were taken as the control. After total DNA was extracted and purified, high-throughput 16S DNA gene sequencing was used to detect the microbiota in tumor tissues and control tissues. Bioinformatics analysis was carried out and the differences between groups were compared. Results:16S DNA PCR showed that there was no significant difference in bacterial load between tumor tissues and control tissues. The α-diversity and β-diversity indexes showed that the community composition of the two groups was similar; the samples were discrete and the colony composition was different, but there was no significant difference between the two groups. The results of Venn diagram showed that there were more operational taxonomic units (OTUs) in non-tumor tissues than in tumor tissues (2 068 vs 1 358), indicating that the bacterial species in normal tissues were more abundant than those in tumor tissues. Compared with the control tissues, the percentages of Prevotellaceae ( Prevotella), Lactobacaceae ( Lactobacillus) and Fusobacteriaceae ( Fusobacterium) in tumor tissues were relatively higher (the average percentage was more than twice that of the control). Further paired comparison of the top ten bacteria in the family and genus abundance of the two groups of samples showed that Pseudomonas decreased significantly in tumor tissues at the family ( P=0.041) and genus ( P=0.041) levels, while Prevotella was significantly enriched in tumor tissues at the family ( P=0.031) and genus ( P=0.007) levels. Conclusions:The bacterial community in the tumor microenvironment of the upper gastrointestinal tumor changed, and the species enriched in the tumor site were mainly oral common anaerobic bacteria, such as Prevotellaceae ( Prevotella), Lactobacaceae ( Lactobacillus) and Fusobacteriaceae ( Fusobacterium), especially Prevotellaceae ( Prevotella).