Study Of The Influence On Rabbit's Trachea,Oesophagus And Artery After Implanted The ～(125)I Seeds

Objective: The interstitial implantation of radioactive ¹²⁵I seeds has very high therapeutic ratio with a low dose rate(LDR) and durative ionizing radiation. As a monotherapy, implanting ¹²⁵I seed exerted long-term local control rate with satisfaction and had been applied in treatment prostate cancer and else tumors in foreign countries extensively. However, the impacts on the normal organs and tissues by ¹²⁵I seed are currently undergoing the period of observation. Here we studied the pathological changes of rabbit'trachea, oesophagus and artery with varying dose and time,and discussed its effect on the normal tissue structure and safety after implanted ¹²⁵I seeds. Thus, this approach will not only provide a proof for clinical application, but also enhance the function of important visceras in tumor therapy and avoid complications.Mathods: 120ordinary male rabbits from the Department of zoology of Zheng zhou University were implanted radioactive ¹²⁵I seeds according to the experimental design. All rabbits were observed the changes of ecumenic complexions, phlebotomized and examined the changes of leucocyte, erythrocyte and hemoglobin preoperative and postoperative. Trachea, oesophagus and artery sections were fixed in 4% paraformaldehyde to fixation, then embed in paraffin wax and stained in parallel with hematoxylin and eosin. Serial 5-μm thick sections were prepared, and the pathological changes were observed by two pathology experts. The Bax was detected by the immunohistochemical method.Metamorph image analysis system was used to analyze the Bax assay results. All values were showed with means±SE. Tested by variance techniques (SNK-q) after Levene analytical method, the results indicate that the statistical tests are considerably significant if P<0.05.Results:1. General conditions: All animals bite and sup naturally,their cuts of operation cicatrized very well without apparent anorexia, nausea and vomit after the operation. All animals were feed till experimental time, their body weight increased. The blood cells were maintained at the relatively stable level(P>0.05).2. Pathological section observed: the sections were observed and given the values for the damage of tissues by two pathology experts with light microscope. The results displayed that the tissues of experimental groups had diferent damage, which related with the dose of seeds. The degree of damage increased with the dose was added (P<0.05), but the damage is reversibility. All damage of experimental groups was repaired in 2 months, and the repair was relevant with the dose of seeds. The repair of groups 1.5mCi was slower than the groups 0.8mCi and 0.5mCi, the diference had statistical significance (P<0.05). The damage was displayed a tissue specific expression: the highest in oesophagus,next in trachea,and much less in artery.3. The expression of TNF-a was increased in all experimental groups in 7 days postoperative (P<0.05).It was the highest values from 14 days to 30 days, and decreased continuously with the time increasing after 30 days (P<0.05),the tissues was renewing in this phase. The experimental groups had no statistical significance in 120 days (P>0.05),it was showed that inflammations were disappeared. However, the Bax of the group 1.5mCi was always higher than that of groups 0.8mCi and 0.5mCi at the same time (P<0.05), and it had, no statistical significance till 120 days (P>0.05). The expression of Bax was displayed a tissue specific expression: the highest in artery,next in trachea,and much less in oesophagus.4. The apoptosis cell analysis: the apoptosis cell was found mostly in the mucosa layer,much less in muscle tissue and connective tissue.Condusions:1. Radioactive ¹²⁵I seed can make damage on normal tissue structure of Rabbit's trachea, oesophagus and artery, and this damage related to seed's radioactive dose, but this damage is reversibility, it can be repaired by tissue itself.2. The endurance of normal tissue for Radioactive ¹²⁵I seed has a value range. It is safe when the dose of seeds less than 0.8mCi in clinic, and it is relatively safe when the radioactive dose of seeds is 1.5mCi, it may induce to apoptosis increasing, and cause irreversible damage to cels when it is used in clinic for long-term.3. The endurance of normal tissue for Radioactive ¹²⁵I seed was: the highest in artery, next in trachea,and much less in oesophagus. Also the highest in muscle tissue, next in connective tissue, and much less in mucosa tissue.