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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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By means of the ultrasonic surface impact (amplitude of 30 μm, strike number of 48,000 times/mm2), nanograins have been achieved in the surfaces of both Ti6Al4V(TC4) and Ti3Zr2Sn3Mo25Nb(TLM) titanium alloys, mainly because of the dislocation motion. Many mechanical properties are improved, such as hardness, residual stress, and roughness. The rotating–bending fatigue limits of TC4 and TLM subjected to ultrasonic impact are improved by 13.1% and 23.7%, separately. Because of the bending fatigue behavior, which is sensitive to the surface condition, cracks usually initiate from the surface defects under high stress amplitude. By means of an ultrasonic impact tip with the size of 8 mm, most of the inner cracks present at the zone with a depth range of 100~250 μm in the high life region. The inner crack core to TC4 usually appears as a deformed long and narrow α-phase, while the cracks in TLM specimens prefer to initiate at the triple grain boundary junctions. This zone crosses the grain refined layer and the deformed coarse grain layer. With the gradient change of elastic parameters, the model shows an increase of normal stress at this zone. Combined with the loss of plasticity and toughness, it is easy to understand these fatigue behaviors. 相似文献
4.
镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折 总被引:5,自引:2,他引:3
目的探讨治疗桡骨近端1/3骨折的理想内固定方法.方法 2001年8月~2004年4月,采用镍钛形状记忆合金环抱接骨板治疗24例桡骨近端1/3骨折.其中男19例,女5例.年龄16~48岁.摔伤9例,压砸伤5例,交通事故伤4例,直接暴力撞击伤3例,高处坠落伤3例.按照形状记忆合金环抱接骨板的安装方法进行骨折复位内固定.术后定期随访,观察骨折愈合及功能恢复情况.结果所有患者均获随访4~21个月,平均10个月.均无术中、术后并发症,切口Ⅰ期愈合;X 线片示骨折均于术后8~12周临床愈合,根据Anderson疗效标准,功能恢复优18例,良5例,可1例,优良率95.83%.结论应用镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折具有创伤小、操作简便安全、固定可靠、组织相容性好、并发症少等优点,有利于促进骨折愈合和肘、腕关节功能康复,是一种治疗桡骨近端1/3骨折的较好方法. 相似文献
5.
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
6.
后路椎体间融合术后融合器脱出的原因及其翻修术 总被引:3,自引:0,他引:3
目的:探讨后路椎体间融合术后融合器脱出的原因及其翻修方法。方法:10例后路椎体间融合术后融合器脱出行翻修术的病例,其中腰椎滑脱症5例,腰椎管狭窄症3例,腰椎间盘突出症2例。手术节段为L4/54例,L5/S1 3例,L4/5+L5/S1 3例;融合器应用BAK(旋入型)7例,聚醚醚酮矩形融合器(PEEK)2例,钛金属矩形融合器1例。于首次术后1~90d内行翻修术。就其脱出原因,再次手术方法及疗效进行分析。结果:融合器脱出的原因:矩形融合器中2例型号太小,1例放置位置偏后;旋入型融合器1例定位错误,其余大都因两枚融合器之间发生碰撞挤压所致。翻修术后获得完整随访资料者8例,随访时间10-36个月,平均17个月,均得到融合,无融合器再次移位或脱出以及内同定的断裂,1例伴有足下垂者遗留患足背伸肌力减弱,其余病例神经症状消除。结论:后路腰椎椎体间融合术后融合器脱出的可能原因有融合器型号偏小导致椎间隙撑开不够,放置位置偏后,两枚融合器不对称或距离太近发生碰撞等。早期、积极的手术翻修能取得较好的疗效。 相似文献
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目的 测试复合矫治弓丝接头的机械性能及分析接头、接头断口变化。方法 测试复合矫治弓丝接头的拉伸强度、剪切强度、扭转强度、弯曲形变残余角,TiNi形状记忆合金丝超弹性,扫描电镜观察及分析接头、断口组织变化。结果 复合矫治弓丝接头抗拉伸强度为32 0~36 0MPa ,剪切强度为2 2 0~2 5 0MPa ,抗扭转强度为30~4 0N·m、断裂时扭转角度不小于1 4 4 0°,弯曲形变残余角为1 2~1 7°;钎焊异质接头中TiNi形状记忆合金丝超弹性几乎没有破坏;接头钎料与TiNi形状记忆合金界面不存在扩散层,与不锈钢丝界面之间有一较宽的扩散层,接头断裂多发生在钎料与TiNi形状记忆合金超弹界面处,部分发生在钎缝中心。结论 复合矫治弓丝机械性能符合正畸临床要求,可应用于临床。 相似文献
9.
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
10.
单枚椎间融合器并对侧经皮椎弓根螺钉固定的生物力学研究 总被引:1,自引:0,他引:1
目的对单枚融合器联合单侧钉棒系统固定的生物力学性能进行评价。方法5具新鲜小牛腰椎标本,建立以下力学模型:A组:双侧开窗+双枚融合器置入+双侧椎弓根钉棒固定;B组:单侧小关节切除+单枚融合器斜向置入+同侧椎弓根钉棒固定;C组:单侧开窗+单枚融合器置入+同侧椎弓根钉棒固定;D组:单侧开窗+单枚融合器置入+对侧椎弓根钉棒固定。在生物力学平台上测试各试验组在不同工况下的ROM值。结果A组的固定最稳固,各工况下ROM值最低。B组的前后抗弯ROM值与A组差异无显著性,其左右侧弯和旋转方向的稳定性较A组有所降低。与B组比较,D组的前后弯曲性能与B组差异无显著性,其左右侧弯方向的ROM低与B组。两组的抗旋转ROM值差异无显著性。C组的左右抗弯及抗旋转性能均差于B、D组。结论单枚椎间融合器联合对侧椎弓根钉棒固定是一种力学性能较为优良组合,可以替代单侧斜向融合器并同侧椎弓根钉棒技术用于下腰椎微创手术。 相似文献