冷热交替消融正常兔肝的影像学与病理学研究

目的 探讨正常兔肝冷热交替消融后消融灶的动态影像学和病理学变化。方法 对20只正常兔肝进行冷热交替消融。消融后1、3、7、14天行CT和CEUS,之后各处死5只兔,观察消融灶的病理学改变。结果 消融灶中心呈凝固性坏死。消融后7天内,坏死灶周围组织充血水肿和急性炎细胞浸润,CT平扫为低或等密度灶,常规超声为低回声为主的混合回声区;增强后均表现为无强化坏死灶和动脉期周边环状增强。消融后7~14天,坏死灶周围组织充血水肿好转,有纤维组织增生、慢性炎细胞浸润及钙化形成,表现为环形强化逐渐减轻消失,消融灶缩小。结论 冷热交替消融可在正常兔肝中产生凝固坏死灶;CT增强扫描和CEUS能有效反映不同时期肝脏消融灶的病理学变化,准确显示消融灶范围。     

电池厂高频感应加热机辐射水平监测及干预研究

目的监测电池厂高频感应加热机电磁辐射水平,评估干预措施的效果。方法用PMM8053B电场强度测量系统对4个电池厂高频加热机岗位进行检测。结果在无屏蔽状况下,所有岗位的电场强度均超过国家职业卫生标准（25 V/m）。屏蔽后分别在干预后3 d、干预后3个月、干预后6个月对相关岗位进行电场强度检测。干预后所有岗位的电场强度均未超过国家职业卫生标准。结论电池厂高频感应加热机作业员工的电场辐射暴露不容忽视,有效防护措施对于控制高频感应加热机的高频污染十分关键。     

神经外科患者气管切开持续加湿加温效果观察

目的:对神经外科气管切开患者的人工气道湿化进行研究探讨。方法:采取随机抽样的方法,将76例气管切开患者分为两组,实验组38例采用持续加湿进行气道湿化,对照组38例采用常规滴入方法进行气道湿化。观察和比较两种人工气道湿化方法的效果。结果:实验组气道加湿加温效果明显优于对照组(P<0.01或P<0.05)。结论:采用持续加湿加温进行气道湿化能有效提高人工气道湿化效果,同时患者舒适、耐受,经济,减少临床护理工作量。     

三种颌面赝复硅橡胶耐热氧老化性能的对比测定

目的：对比研究ZY-1、SY-1及A-2186三种赝复硅橡胶热氧老化前后的机械性能,评价ZY-1硅橡胶的耐热氧老化性能。方法：在相同条件下分别对三种硅橡胶材料老化前后的机械性能进行测定,并对结果进行统计学分析。结果：ZY-1、A-2186和SY-1硅橡胶在热氧老化后,拉伸强度、扯断伸长率、撕裂强度以及硬度均呈现下降趋势,ZY-1热氧老化后性能变化百分率和A-2186无明显差异,ZY-1、A-2186硅橡胶的扯断伸长率、永久变形率（3 min后）、撕裂强度的老化百分变化率明显小于SY-1硅橡胶。结论：ZY-1加成型赝复硅橡胶具有良好的耐热氧老化能力。     

Do we need pacemakers resistant to magnetic resonance imaging?

AIMS: Manufacturers of pacemakers (PM) and of magnetic resonance imaging (MRI) devices state that MRI scanning of PM wearers is contraindicated. This paper tries to summarise which effects can interfere with PM, what can be hazardous, and how treatment of PM in MRI can be modified to guarantee compatibility. MATERIAL AND METHODS: All PM tested were from deceased patients. Reed contact thresholds and reactions were investigated in low magnetostatic fields and compared with those in strong magnetostatic fields. Influence of gradient fields on PM and heating due to radiofrequency (RF) pulses were estimated. Thirty Legal Medicine Departments were questioned whether deaths of PM patients during MRI are known. RESULTS: Reed contacts are influenced above 0.7 mT. In MRI fields only 28% of the PM in magnet mode remained so in all orientations. Of synchronous PM, 76% remained synchronous in all orientations. Gradient fields can influence sensing but cannot stimulate. Power density and temperature rise produced by RF fall rapidly with distance. Our question revealed six deaths. All suffered from sick-sinus-syndrome and all were not PM dependent. In three cases ventricular fibrillation was proven as the cause of death. DISCUSSION: Asynchronous pacing due to magnetostatic and gradient fields may be problematic in patients with spontaneous rhythm. To avoid them, PM triggered MRI scan restricted to refractory period is proposed. Neither inhibition of PM nor heating of the electrode poses real risks. So far, we have examined eight patients 12 times in MRI triggered mode without problems.     

Effect of chronically induced thermotolerance on thermosensitization in CHO cells

Chronic thermotolerance was induced in Chinese hamster ovary (CHO) cells by pretreatment at 40°C for various times ranging from 15 min to 16 h. The thermotolerant cells were either exposed to single heat treatments at 43 °C or subjected to step-down heating consisting of a priming treatment at 43 °C for 90 min immediately followed by a graded test treatment at 40°C. The results showed that chronic thermotolerance affected the thermal sensitivity of step-down-heated CHO cells in two ways: by lowering the effectiveness of the priming treatment at 43 °C and by reducing the response to the test treatment at 40°C. The effect on the priming treatment corresponds to a reduction in the effective heating time, i.e. the thermotolerant cells respond as if they were exposed to 43°C for times shorter than 90 min. It was further shown that, for a given conditioning treatment, the effectiveness of both the priming and the test treatment was reduced by the same factor; the thermotolerance ratios determined for 43°C and 40°C showed an identical dependence on the duration of the thermotolerance-inducing conditioning treatment. Since thermotolerance development did not reverse heat sensitization by step-down heating, it is concluded that thermotolerance and thermosensitization are distinct phenomena which act independently.