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Many nanoparticles (NPs) have toxic effects on multiple cell lines. This toxicity is assumed to be related to their accumulation within cells. However, the process of internalization of NPs has not yet been fully characterized. In this study, the cellular uptake, accumulation, and localization of titanium dioxide nanoparticles (TiO2 NPs) in rat (C6) and human (U373) glial cells were analyzed using time-lapse microscopy (TLM) and transmission electron microscopy (TEM). Cytochalasin D (Cyt-D) was used to evaluate whether the internalization process depends of actin reorganization. To determine whether the NP uptake is mediated by phagocytosis or macropinocytosis, nitroblue tetrazolium (NBT) reduction was measured and the 5-(N-ethyl-N-isopropyl)-amiloride was used. Expression of proteins involved with endocytosis and exocytosis such as caveolin-1 (Cav-1) and cysteine string proteins (CSPs) was also determined using flow cytometry.TiO2 NPs were taken up by both cell types, were bound to cellular membranes and were internalized at very short times after exposure (C6, 30 min; U373, 2 h). During the uptake process, the formation of pseudopodia and intracellular vesicles was observed, indicating that this process was mediated by endocytosis. No specific localization of TiO2 NPs into particular organelles was found: in contrast, they were primarily localized into large vesicles in the cytoplasm. Internalization of TiO2 NPs was strongly inhibited by Cyt-D in both cells and by amiloride in U373 cells; besides, the observed endocytosis was not associated with NBT reduction in either cell type, indicating that macropinocytosis is the main process of internalization in U373 cells. In addition, increases in the expression of Cav-1 protein and CSPs were observed.In conclusion, glial cells are able to internalize TiO2 NPs by a constitutive endocytic mechanism which may be associated with their strong cytotoxic effect in these cells; therefore, TiO2 NPs internalization and their accumulation in brain cells could be dangerous to human health. 相似文献
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目的:分析钛-瓷修复体失败的原因。方法:对38例瓷裂的钛-瓷修复体进行分析:①肉眼观察烤瓷崩瓷部铸件的表面颜色并用便携式厚度测试仪测量其厚度,与未发生瓷裂的正常镰铬合金烤瓷比较;②观察烤瓷崩瓷的部位;③X-ray检测铸件内部气孔。结果:本组崩瓷的钛-瓷修复体,其断层或有气泡,或金属表面氧化层明显增厚(P〈0.05)。而且,所有发生崩瓷的部位均在受力点或因技工本身操作不当引起。结论:钛-瓷修复体失败的原因与加工过程中工艺、瓷的受力点以及与钛元素化学性能有关。 相似文献
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The purpose of this study was to determine the dosimetric impact of a neurosurgical titanium mesh in patients treated with 6- and 18-MV photon beams. The effects of a 0.4-mm-thick titanium mesh on the dose profile at 3 regions within a solid water phantom were measured using extended dose range-2 (EDR2) film for 6- and 18-MV photon beams. All measurements were performed with the titanium mesh placed at a depth of 1.5 cm in the phantom. Films were exposed immediately above the mesh, immediately below the mesh, and at a depth of 5 cm from the surface of the phantom. The films were scanned using a scanning densitometer. In the region directly above the titanium mesh, there was an increase in dose of 7.1% for 6-MV photons and 4.9% for 18-MV photons. Directly below the titanium mesh, there was an average decrease in dose of 1.5% for 6-MV photons and an increase of 1.0% for 18-MV photons. At 5-cm depth, for 6- and 18-MV photons, there was a decrease in dose of 2.2% and 0.6%, respectively. We concluded that for cranial irradiation with high-energy photons, the dosimetric impact of a 0.4-mm titanium mesh is small and does not require modification in treatment parameters. 相似文献
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二氧化碳吸收剂中水分对七氟醚分解反应的影响 总被引:2,自引:0,他引:2
目的 研究模拟紧闭反应器内干燥的二氧化碳 (CO2 )吸收剂及自身含水对七氟醚分解的影响。方法 在紧闭反应器 (1 6 0ml)内 ,分别装钠石灰、钡石灰、干燥钠石灰和干燥钡石灰 (各 2 5g)。在密闭状态下注入液态的七氟醚 4 0 0 μl,放入 5 0℃水浴内反应 6h ,分别在 5、1 5、30、4 5、6 0min、以后每 30分钟至 36 0分钟采样 ,用气相色谱法分析。测定七氟醚的分解产物。结果 钠石灰组出现复合物A、B ,在其他组七氟醚产生 5种分解产物。复合物A∶干燥钡石灰 >干燥钠石灰 >钡石灰和钠石灰组。干燥钡石灰组明显高于其他两组 (P <0 0 5 )。复合物B∶干燥钡石灰组 <钡石灰组 <干燥钠石灰组 (P <0 0 5 )。复合物C、D、E ,以干燥钡石灰组最为明显 (P <0 0 5 )。各组均未检测到CO。结论 在 5 0℃的紧闭反应器内 ,七氟醚与干燥的CO2 吸收剂反应剧烈 ,未产生CO ;国产钠石灰优于钡石灰 ,在紧闭容器内自身含水可以抑制分解反应 相似文献
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Abstract Several methods have been used to predict successful weaning and extubation among chronic obstructive pulmonary disease (COPD) patients. The objective of this study is to determine whether carbon dioxide recruitment threshold (PCO2 RT) can be used as adjunct to conventional weaning parameters to predict early weaning and successful extubation. Twelve COPD patients who were ready to be extubated based on conventional weaning parameters were divided into group A ( n = 7) and group B ( n = 5). Group A were those patients with better weaning parameters and hence a higher probability of successful extubation as compared to group B. Carbon dioxide apnoeic threshold (PCO2 AT) was obtained by hyperventilating the patient using an increment of two breaths per min until apnoea occurs. At this point, the PCO2 AT or the PaCO2 during said apnoeic period was recorded. A dead space of 150 cc is then added to the circuit until the patient starts to breathe as evidenced by the sensitivity trigger indicator. The PCO2 obtained at this period is termed PCO2 RT. After weaning for 30 min on a T-tube, another arterial blood gas is determined and this is called the PCO2 SB or the CO2 level after 30 min on spontaneous breathing. If the PCO2 SB-PCO2 RT difference is high with a sensitivity of 85.71% and specificity of 100% vs sensitivity of 57.14% and specificity of 60% using the conventional weaning parameters. Thus an increase in PCO2 SB at 30 min T-tube is indicative of impending respiratory pump failure and that other causes of failure to wean must be investigated. 相似文献