Hyperacute experimental model of rat lung transplantation using a coronary shunt cannula

BACKGROUND Lung transplantation is a well-established treatment of end-stage lung disease.A rodent model is an inexpensive way to collect biological data from a living model after lung transplantation.However,mastering the surgical technique takes time owing to the small organ size.AIM To conduct rat lung transplantation using a shunt cannula(SC)or modified cannula(MC)and assess their efficacy.METHODS Rat lung transplantation was performed in 11 animals in the SC group and 12 in the MC group.We devised a method of rat lung transplantation using a coronary SC for coronary artery bypass surgery as an anastomosis of pulmonary arteri-ovenous vessels and bronchioles.The same surgeon performed all surgical proce-dures in the donor and recipient rats without using a magnifying glass.The success rate of lung transplantation,operating time,and PaO2 values were com-pared after 2-h reperfusion after transplantation.RESULTS Ten and 12 lungs were successfully transplanted in the SC and MC groups,respectively.In the SC group,one animal had cardiac arrest within 1 h after reperfusion owing to bleeding during pulmonary vein anastomosis.The opera-ting time for the removal of the heart-lung block from the donor and preparation of the left lung graft was 26.8±2.3 and 25.7±1.3 min in the SC and MC groups,respectively(P=0.21).The time required for left lung transplantation in the recipients was 37.5±2.8 min and 35.9±1.4 min in the SC and MC groups,respectively(P=0.12).PaO2 values at 2 h after reperfusion were 456.2±25.5 and INTRODUCTION Lung transplantation is a well-established treatment of end-stage lung disease.Many immune and non-immune mech-anisms in lung transplantation are highly complex,and post-transplant complications such as infections and primary and chronic lung allograft dysfunction must be reduced to improve survival.Therefore,there is a need for immunological and pathophysiological analyses using animal lung transplantation models.The rat lung transplantation model was first reported in 1971[1],followed by the Mizuta Cuff model[2]in 1989.Since then,various improvements in surgical techniques,cuffs,and instruments have been reported[3-7].The advantage of using a rodent model is that it permits inexpensive collection of biological data from a living model after lung transplantation.Although trained surgeons can perform the transplantation procedure,mastering the surgical technique takes time due to the small size of the organs.The risks associated with this technique include damage to the vulnerable pulmonary artery(PA)and pulmonary vein(PV)vessel walls during anastomosis,as well as stenosis of the anastomotic site.We developed an anastomotic technique using a coronary shunt cannula(SC)for cardiac coronary artery bypass surgery as an alternative to the previously reported cuff method[2-6].This method enables anastomosis by inserting and ligating a cannula into the lumen of the PA,PV,and bronchus(Br),which is simpler and more reliable than conventional methods.This study aimed to determine problems with rat lung transplantation using the SC,develop an improved cannula,and investigate its utility.RESULTS After creating 11 lung transplantation model animals in the SC group and 12 in the MC group,all animals underwent reperfusion.One animal in the SC group had cardiac arrest 1 h after reperfusion due to hemorrhage caused by vessel wall injury during PV anastomosis.Two hours after reperfusion,we visually confirmed the maintenance of recipient hemody-namics and blood flow in the graft pulmonary cannula in 10 animals in the SC group and 12 in the MC group.The operating time for the removal of the heart-lung block from the donor and graft lung creation was 26.8±2.3 min in the SC group and 25.7±1.3 min in the MC group(P=0.21,Table 1).The duration for left lung transplantation into the recipient was 37.5±2.8 min in the SC group and 35.9±1.4 min(P=0.12,Table 1)in the MC group.Although no significant difference was found between the SC and MC groups,animals in the MC group experienced a slightly shorter operating time,smoother surgical technique,and less stressful procedure for the surgeons compared with those in the SC group.The graft lung coloration(Grade 1/2/3)after reperfusion was 0/2/8(SC group)and 0/2/10(MC group),and all grafts were reported to be successful,except in one animal in the SC group that had cardiac arrest(Table 2).The PaO2 values after 2 h of reperfusion were 456.2±25.5 mmHg in the SC group and 461.2±21.5 mmHg in the MC group(P=0.63,Table 3),showing no significant difference between the groups.

具有缺陷和应力限值的预应力钢支撑柱屈曲性能

通过预应力支撑加固的钢柱,一般增加了轴向抗压强度。过去,十分强调获得更高的临界屈曲荷载,然而,后屈曲性能是结构安全性和功能的重要保证。对具有几何缺陷和与可能的材料失效相关的应力极限的支撑柱的屈曲性能进行检验。考虑有几何缺陷支撑柱的屈曲性能,采用Rayleigh-Ritz方法对几何非线性模型公式化,并通过有限元方法进行验证。研究显示:对于承受最高临界荷载的预应力状态,系统对有几何缺陷的柱更为敏感。对某一给定形状结构,实际的最大荷载似乎随着预应力的增加而增加。研究建议:最佳的预应力取值应该大于基于传统方法的线性分析的结果。