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本实验以相对半定量的全小肠嗜银染色计数嗜银细胞的方法对60Coγ线不同剂量及不同时间全身一次性照射后小鼠全小肠嗜银细胞的变化进行了观察,发现1~7Gy照射后72小时,嗜银细胞数量随着照射剂量的增加逐渐增多,7Gy达峰值,8 Gy后则随剂量的增加呈指数减少,至160Gy仅为对照的11%.变化最显著的区域在10~30Gy.照射后不同时间的变化结果表明,8.10Gy照后1天嗜银细胞减少60%,2天开始回升,4~7天出现超常,2周时恢复正常.15、20Gy照后1夭减少显著,2天略见回升,8~5天又复减少.30Gy照后嗜银细胞呈进行性减少直至动物死亡.这一实验结果提示小肠嗜银细胞与电离辐射的量效关系有独特的规律性变化. 相似文献
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《Ultrasound in medicine & biology》2020,46(2):405-414
Differentiation between epicardial and endocardial ventricular activation remains a challenge despite the latest technologies available. The aim of the present study was to develop a new tool method, based on electromechanical wave imaging (EWI), to improve arrhythmogenic substrate activation analysis. Experiments were conducted on left ventricles (LVs) of four isolated working mode swine hearts. The protocol aimed at demonstrating that different patterns of mechanical activation could be observed whether the ventricle was in sinus rhythm, paced from the epicardium or from the endocardium. A total of 72 EWI acquisitions were recorded on the anterior, lateral and posterior segments of the LV. A total of 54 loop records were blindly assigned to two readers. EWI sequences interpretations were correct in 89% of cases. The overall agreement rate between the two readers was 83%. When in a paced ventricle, the origin of the wave front was focal and originated from the endocardium or the epicardium. In sinus rhythm, wave front was global and activated within the entire endocardium toward the epicardium at a speed of 1.7 ± 0.28 m·s−1. Wave front speeds were respectively measured when the endocardium or the epicardium were paced at a speed of 1.1 ± 0.35 m·s−1 versus 1.3 ± 0.34 m·s−1 (p = NS). EWI activation mapping allows activation localization within the LV wall and calculation of the wave front propagation speed through the muscle. In the future, this technology could help localize activation within the LV thickness during complex ablation procedures. 相似文献
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