动物造模,药效评价,食管狭窄 z-bio 2024-08-26 450

　　(1) Copy method: Adult Beagle dogs weighing 8-14kg were anesthetized by intravenous injection of pentobarbital sodium at a dose of 30mg/kg body weight. The dogs were then fixed on the operating table while lying on their side, and the neck surgical area was routinely disinfected and shaved; Cut open the skin of the neck with aseptic surgery and free the esophageal wall. Take a piece of fascia lata with a size of about 2cm × 2cm × 3cm from the outer side of the hind leg of the dog, and place it into an esophageal stent under endoscopic guidance, positioning its upper end on the free segment of the esophagus in the neck. Attach the fascia lata to the outer wall of the esophagus at the stent placement site, and fix it with medical stainless steel wire in two places. On the one hand, it can strengthen the toughness of the esophageal wall; On the other hand, it can prevent sutures from hanging through the esophageal wall. During the modeling surgery, a small amount of penicillin is locally injected. After surgery, the model animals are fed a semi liquid diet and observed for 1-10 weeks under conventional feeding conditions. During the placement period, carefully observe the general condition, weight, and dietary changes of the model dog every day. The morphological changes of the inner diameter of the esophagus and the various layers of tissue on the esophageal wall at the site of the model dog's placement were observed. Through regular observation of the pathological tissue morphology of the model animal's esophagus under light and electron microscopy specimens, the results showed significant characteristics of esophageal stenosis and morphological changes.

　　(2) The characteristics of the model are that the model animals can resume their diet on the second day after surgery. Within three weeks after stent implantation, there were no abnormalities in the amount of food consumed by the model animals compared to before surgery, and their weight did not significantly decrease. However, their activity decreased significantly compared to before surgery, and the animals did not experience repeated vomiting or choking. After 3 weeks of placement, the food intake of the model dog significantly decreased, and repeated vomiting and continuous swallowing movements began to occur. The weight was significantly reduced compared to before surgery, and the activity level was further reduced. Two weeks after surgery, the esophageal tissue of the model animal showed significant hyperplasia, with the majority of the stent structure covered by the hyperplasia tissue. The esophageal mucosa was extensively congested and edematous, with occasional necrosis, exudation, and ulceration. The esophageal wall at the stent placement site was significantly thickened, and the proliferation of the esophageal walls at both ends of the stent was more pronounced than in the tube body. Four weeks after surgery, the esophageal tissue of the model animal was examined, and it was found that a large amount of proliferative tissue had completely covered the inner wall of the stent and connected into pieces. The stent was deeply embedded in the esophageal wall, and the lumen was significantly narrower than normal. The mucosa was still slightly congested, with occasional necrosis and ulcer formation. The general morphology of the esophagus after 8 weeks of surgery is similar to that at 4 weeks, but the proliferative tissue extends widely beyond the stent structure into the lumen, and the lumen is significantly narrowed. Under light microscopy, it was observed that one week after stent implantation, the squamous epithelium in the esophageal tissue showed significant proliferation and thickening, with disordered cell layers. The volume of basal layer cells increased, and the nuclei were deeply stained. The epithelial basal layer and lamina propria were in a staggered state; Submucosal congestion, vascular proliferation, infiltration of inflammatory cells, and formation of fibrous connective tissue can be seen with scattered fibroblasts. Two weeks after surgery, the squamous epithelium grew irregularly and staggered along the stent mesh, with dense epithelial cells, deep nuclear staining, and increased volume. The submucosal glands were significantly reduced, with a large number of inflammatory cells infiltrating. The number of fibroblasts increased significantly, and the proliferation of fibrous tissue intensified compared to before. The granulation tissue proliferation was obvious, and the muscle layer became thinner. Four weeks after surgery, the epithelial morphology was similar to that of two weeks after surgery, but the glandular tissue in the lamina propria almost disappeared. A large amount of fibrous tissue proliferation was observed, which was significantly dense, and scattered inflammatory cell infiltration was still visible. Fibroblasts were significantly reduced, and the muscle layer was noticeably atrophied and thinned. The morphology of the tissue under light microscopy at 8 weeks after surgery is basically the same as that at 4 weeks after surgery, and the arrangement of epithelial cells tends to be neat; The subepithelial fibrous tissue further increases and becomes denser, while the inflammatory cells significantly decrease. The pathological changes of proliferative tissues at the upper, middle, and lower ends of the stent are basically consistent. Observation of electron microscopy ultrastructure showed that one week after surgery, the volume of nuclei in the basal layer of esophageal mucosal epithelial cells increased, and a large number of rough endoplasmic reticulum could be seen in the cytoplasm; Expansion of intercellular spaces in the superficial layer of the epithelium. Two weeks after surgery, fibroblasts in a state of vigorous secretion can be seen in the submucosal layer, with large nuclear volume and abundant endoplasmic reticulum. Four weeks after surgery, active fibroblasts were still visible in the tissue, and scattered fiber bundles were formed around the cell protrusions. A large number of fiber bundles were also observed in the tissue 8 weeks after surgery.

　　(3) A comparative medicine animal model of esophageal stenosis was established using this method. Due to the application of the "autologous fascia lata transplantation fixation method" to place esophageal stents, all stents were effectively fixed in the esophageal cavity after one week of postoperative follow-up. There were no surgical related complications within two weeks after surgery, and the success rate of the model was as high as 100%. Medical grade stainless steel filaments were used for suturing during the surgery to avoid the possibility of breakage; The use of autologous fascia lata reinforcement has the following advantages due to the characteristics of fascia lata: it can prevent perforation of the esophageal wall, have local repair effects, and avoid foreign body stimulation of the esophageal wall causing hyperplasia. Therefore, compared with animal models of esophageal stent stenosis established by other methods, the "esophageal stent restenosis" animal model replicated by this method has the advantages of simple method, reliable results, short modeling period, low sample consumption, and high model success rate. However, due to the need for surgery on the esophagus during modeling, it can cause varying degrees of traumatic inflammation in the local esophageal wall, which has a certain impact on the use and evaluation of model animals.