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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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BackgroundThe new methods of osteoarthritis treatment are in constant demand due to the complexity of the early diagnosis and therapy. Specific features of Сhlorin e6 derivative (Ce6) accumulation in knee joint tissues and the efficiency of photodynamic therapy (PDT) of gonarthritis were studied.MethodsThe experimental research was conducted on the model of posttraumatic gonarthritis on rabbits. The analysis of dynamics of change of Ce6 concentration in tissues of a knee joint was carried out by the method of fluorescent diagnostics. The intra-joint PDT was carried out using 662 nm laser with energy density of 120–150 J/cm2 and a sapphire diffuser. An analysis of slices was conducted to confirm the anti-inflammatory effect through apoptosis.ResultsThe method of fluorescent spectroscopy revealed that the highest amount of Ce6 was accumulated in the synovial membrane of a damaged knee joint 2.5 h after its intravenous introduction. On 14th day after gonarthritis modeling but before PDT the synovial membrane showed signs of synovitis. On 21st day after PDT the synovial membrane possessed noticeable villous structure, and no cells of inflammatory nature were observed.ConclusionFluorescent diagnostics in knee joint tissues can be used in clinical practice of gonarthritis before, during and after PDT for monitoring the Ce6 accumulation and for treatment control. Optimal radiation energy density was determined to be 150 J/cm2. In the studied time intervals (5–25 min) no dependency of PDT effect on irradiation time at the same energy density was observed. The analysis of results of clinical and morphological research shows that PDT is a low-invasive method of gonarthritis treatment with a high degree of efficiency and selectivity. 相似文献
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This paper presents values for density and mass attenuation coefficient of building materials commonly used in Brazil. Transmission measurements were performed to provide input information for simulations with MCNP4B code. The structure for the clay bricks was simulated as a mix of all material layers and an effective density determined. The mass attenuation coefficients were determined for the 50-3,000 keV gamma-ray energy range. A comparison with results for similar materials found in the literature showed good agreement. 相似文献