动物模型,阑尾炎 z-bo 2020-08-07 568

　　(1) Reproduction method Adult rats, fixed after anesthesia, open the abdomen under aseptic conditions, remove the appendix and the terminal ileum and the intestinal segment connected with the mesentery of the appendix (hereinafter referred to as the adjacent intestinal segment) out of the abdominal cavity and place it on the wall. Cut the mesangium at the tip of the appendix, squeeze the intestinal contents of the tip of the appendix into the intestinal lumen of the proximal end of the appendix, and ligate the appendix tube with 1 cm from the tip of the appendix. Place the tip of the ligated appendix between the root of the ileum and the adjacent intestine. Suture the ileum root and the adjacent intestine with a small round needle and thin silk thread (000#) with a stitch (penetrating only the serosa muscle layer), and then embed the ligated appendix under it. Then follow the terminal ileum from the distal end to the proximal end and close the adjacent intestinal segment with 1-2 stitches tightly to bury the appendix under the sutured intestinal segment. Put all the external intestines into the abdominal cavity, close the abdomen with two sutures, wrap the wound with sterile gauze, and return to the cage for observation. Or adult rabbits, fixed on the operating table after anesthesia, skin preparation, disinfection and draping, a 6cm mid abdominal incision under aseptic conditions, the appendix is lifted out of the cecum, and a No. 4 silk thread is placed at the root of the appendix against the wall of the appendix. The appendix is ligated with the mesangium, then the appendix is returned to the abdominal cavity, and the abdomen is closed layer by layer. After the operation, the animal's body temperature was measured at the specified time point, the bacterial culture of the necrotic appendicitis cavity contents, the size of the cyst or necrotic appendix, and the macroscopic pathological observation and microscopic examination of histomorphological changes were performed.

　　(2) Model characteristics 15 days after operation, the appendix of the rat showed purulent necrosis with a layer of fibrous cyst which contains a lot of bacteria. The success rate of the model is nearly 100%. The appendix is hyperemia, edema, and thickening at 6-12h after operation in rabbits; at 12-24h, the appendix is swollen and thickened more obviously, and the outer pus coating adheres to the surrounding intestinal canal. Spot-like hemorrhages can be seen on part of the appendix wall, and there are in the abdominal cavity. Purulent exudate appears. The surrounding intestines adhered to the appendix abscess also showed obvious edema, congestion, or even mesenteric abscess formation. The bacterial culture of the peritoneal exudate has the growth of E. coli. After 24h, the rabbit's body temperature can rise to about 40℃. During the whole model building process, the model animals were sluggish, without eating or drinking, their abdomens were full, and they died within 2 to 4 days.

　　(3) Comparative medicine Bacterial infection and obstruction of the appendix cavity are the two main factors of appendicitis. In this experiment, the appendix tube was artificially ligated, which caused the appendix cavity to be blocked and induced an acute appendicitis model. The etiology of this model is similar to that of the clinic, and the pathogenesis and pathological types are similar to those of humans. The appendix was congested, edema, and thickened in rabbits 6 to 12 hours after surgery, and pathological examination confirmed acute simple appendicitis; 12 to 24 hours after surgery, the appendix was significantly swollen, the serous membrane was highly hyperemic, and purulent exudate appeared in the abdominal cavity, which contained A large number of Escherichia coli, the pathological changes belong to acute cellulitis appendicitis; more than 24 hours after the operation, the appendix necrosis, necrotic perforation occurs, and the pathological changes are quite acute gangrenous appendicitis. The appendicitis model is often replicated in rats or rabbits. Among them, the rat model replication method is simple, the operation cycle is short, the entire process only takes 10-15 minutes, the evaluation indicators are objective and clear, including animal body temperature, necrotic appendix lysate bacterial culture, cyst or necrotic appendix size, and pathology The model has a high success rate due to morphological changes. Therefore, it can be used in the study of appendix abscess in the field of acute abdomen, and can also be used as a model for drug activity screening and efficacy evaluation for the prevention and treatment of appendix abscess or infectious inflammation. However, when making the model, the intestinal segment sutured to embed the necrotic appendix must be made into a complete package to prevent the contents of the necrotic appendix from flowing into the abdominal cavity and causing diffuse peritonitis. ②Because the length of the ligated appendix is positively related to the condition, the length of the appendix ligation should be controlled at a reasonable level. Usually the length can be controlled within 3cm. It is not easy to form a complete wrap after all ligation. Too many suture needles will not meet the physiological characteristics. And easy to form intestinal obstruction. ③In order to prevent human-induced intra-abdominal contamination, all surgical operations must comply with the principle of sterility, and the sutured intestinal segment should be returned to the abdominal cavity in a better arrangement to avoid the formation of intestinal infarction and animal death. Although the rabbit model has a shorter survival period, its pathogenesis and pathological manifestations are closer to the clinic, and it is especially suitable for the study of the evolution of acute appendicitis and treatment options. When copying the model, care must be taken not to damage the appendix arteries and veins during the operation to ensure the appendix’s blood supply.