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[Local injection of BTX-A prevents iatrogenic anterior urethral stricture in rabbits]. Liu Xiao-He,Wang Ying,Liu Gang,Qin Jing-Li,Li Wei-Wei,Gao Dian-Jun Zhonghua nan ke xue = National journal of andrology Objective:To investigate the preventive effect of local injection of botulinum toxin type A (BTX-A) against iatrogenic anterior urethral stricture (IAUS) in New Zealand male rabbits. METHODS:Sixteen adult New Zealand male rabbits were randomly divided into an experimental and a control group of equal number. The model of IAUS was established in the rabbits by incision of the ventral urethra of the penile segment and electrocoagulation of the urethral mucosa. The rabbits of the experimental group were injected with 10 U of BTX-A solution and those of the control group with 1.0 ml of normal saline into the electrocoagulated submucosa of the urethra. At 30 days after modeling, retrograde urethrography was performed and the scarred urethral tissue harvested for HE and Masson staining. RESULTS:No systemic symptoms of botulinum toxin poisoning were observed in either group of the rabbits. Retrograde urethrography showed statistically significant differences between the control and experimental groups in the diameter of the urethra ([0.15 ± 0.08] vs [0.50 ± 0.23] cm, P < 0.05) and the stenosis ratio (3.68 ± 1.22 vs 1.29 ± 0.15, P < 0.05). Urethrography revealed obvious hyperplasia and contracture of urethral scar with high bulge and narrow urethral cavity, while HE and Masson staining exhibited absence or discontinuity of the urethral epithelium, submucosal fibrosis with infiltration of a large number of fibroblasts, and hyperplasia and thickening of collagen fibers (blue) in the control group. All the changes above were slight and the urethral epithelium was continuous in the experimental group. CONCLUSIONS:Local injection of BTX-A reduced the incidence of iatrogenic anterior urethral stricture after iatrogenic acute heat injury in New Zealand male rabbits.
An Experimental Model of Anterior Urethral Stricture in Rabbits With Local Injections of Bleomycin. Hua Xiaoliang,Xu Yujie,Liu Gang,Sun Lin,Zhang Hao,Pan Qiufeng,Liu Di,Li Bing Urology OBJECTIVE:To develop an experimental model of anterior urethral stricture in rabbits using a bleomycin (BLM) injection technique. MATERIALS AND METHODS:Thirty adult male New Zealand rabbits were randomly divided into 4 groups. In group 1 (BLM group), BLM was injected into the urethral submucosal tissue every other day through a catheter for 6 weeks at the 3-, 6-, 9-, and 12-o'clock positions of the urethra in 12 rabbits. In group 2 (phosphate-buffered saline [PBS] group), PBS was injected instead of BLM in 6 rabbits. In group 3 (stricture control group), an 8 × 20 mm urethral defect was created in 6 rabbits. In group 4 (normal group), 6 normal rabbits were included. All rabbits in the PBS group and stricture control group, as well as 6 rabbits in the BLM group, were sacrificed at 6 weeks. The remaining 6 rabbits in the BLM group were sacrificed at 10 weeks. Urethrography was performed in all rabbits before sacrifice, and the urethra was harvested for histologic analysis. RESULTS:All rabbits in the BLM group showed mild urethral stricture at 4 weeks and significant urethral stricture at 6 weeks, without spontaneous resolution of the stricture at 10 weeks. No urethral stricture was observed in the PBS group at 4 and 6 weeks. Histologic examination confirmed the presence of fibrosis in the BLM group without spontaneous improvement. CONCLUSION:BLM injection can induce an experimental model of anterior urethral stricture in rabbits. This simple, highly efficient, reproducible method can be carried out in any laboratory. 10.1016/j.urology.2017.12.031