Internalization of titanium dioxide nanoparticles by glial cells is given at short times and is mainly mediated by actin reorganization-dependent endocytosis

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.     

钛瓷瓷裂的临床研究和原因分析

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。     

后路椎体间融合术后融合器脱出的原因及其翻修术

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。     

钛对大肠杆菌生长影响的实验研究

以草酸钛钾溶液为受试物，用无菌操作法在不同浓度试验水样及不含钛的对照水样中加入大肠杆菌稀释液1ml（含菌300个），观察6小时和1－7天的细菌生长情况。结果各受试组与对照组比较，10.0mg／L和1．0mg／L组接触6小时至7天大肠杆菌生长均有明显的抑制作用；0．1mg／L组接触6－24小时显示抑制作用，但第4天开始菌落减少的速度比对照组缓慢。提示钛对大肠杆菌的生长有抑制作用，其作用阈浓度为1．0mg／L，阈下浓度为0，1mg／L。     

Effects of neurosurgical titanium mesh on radiation dose

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.     

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

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。     

椎弓根螺钉联合椎间植骨融合器治疗腰椎滑脱症的远期疗效分析

[目的]探讨椎弓根螺钉系统联合椎间植骨融合器治疗峡部不连性腰椎滑脱症的远期疗效。[方法]自1996年10月~2002年10月本组收治峡部不连性腰椎滑脱症105例,随访资料齐全者86例。所有患者均行椎弓根螺钉系统复位滑脱,椎间植骨融合器行椎间融合固定。62例患者中1枚融合器从后斜向前呈45°植入,24例为2枚融合器从后向前垂直植入。随访测定固定节段的椎体间有无移位、滑脱有无复发,比较术前、术后2周及随访时固定椎间隙高度与近端第2椎间隙高度比值的变化。[结果]随访2~8年,平均35个月。根据NaKai评分标准,本组优56例,良13例,可17例,优良率为80.23%。Ⅰ度腰椎滑脱19例术后全部解剖复位;Ⅱ度腰椎滑脱51例中5例遗留Ⅰ度滑脱;Ⅲ度腰椎滑脱16例中4例留有Ⅰ度滑脱。末次随访时使用1枚融合器或2枚融合器所固定的椎间隙高度与近端第2椎间隙高度的比值与术后2周时的比值相比有所减低,滑脱无复发。[结论]椎弓根螺钉加椎间植骨融合器治疗腰椎滑脱症手术疗效满意,显著提高融合率,预防神经根管狭窄、神经卡压的发生,减少术后断钉和滑脱复发等问题。     

经后路钛网椎板成形侧块内固定术治疗脊髓型颈椎病的疗效观察

目的 观察后路钛网椎板成形侧块内固定加植骨术治疗脊髓型颈椎病的临床效果。方法 自1999年至今，共有16例脊髓型颈椎病患者经后路钛网椎板成形侧块内固定加植骨术治疗，对治疗结果进行临床及X线评定。结果 通过平均2年5个月的随访，所有病例都得到了改善，其中优6例、良8例、可2例，优良率为93．8％；术后椎管矢状径平均增加4．2mm，钛网无位置变化，并已被再生骨固定。结论 在进行后路减压的同时，钛网椎板成形及侧块内固定，尤其适用于有节段性不稳的脊髓型颈椎病并椎管狭窄、后纵韧带骨化症的治疗。     

颈前路钛网植骨融合术后钛网沉陷的原因探讨

目的：探讨颈前路钛网植骨融合术后钛网发生沉陷的原因及其对临床疗效的影响，并提出相应对策。方法：回顾性分析在我院行颈前路钛网植骨融合术的各类颈椎疾患患者179例，观察患者骨密度、钛网修剪及放置情况、终板处理情况、钢板类型、植骨及椎体撑开情况等。采用日本骨科学会（JOA）评分法评价神经功能的变化。结果：有17例患者发生钛网沉陷，沉陷的原因主要为骨密度下降、钛网修剪放置不当、术中过度撑开、终板刮除过多、使用非限制性钢板、采用同种异体骨植骨、螺钉进钉深度过浅和方向不当、钢板放置位置偏斜等。术后所有患者JOA评分比术前平均增加3．5分（P〈0．01）。162例未发生钛网下沉患者术后3个月和6个月的JOA评分比术前平均增加4．4分和4．7分：发生钛网下沉患者中。6例有临床症状者沉陷时和沉陷3个月时的JOA评分为2．9分和3．8分．7例无临床表现者为3．3分和3．9分．4例有临床症状行翻修手术者翻修术后1周和3个月时JOA评分比翻修前提高3．3分和3．7分。结论：颈前路钛网植骨融合术后可发生钛网下沉，骨质疏松患者应该避免使用钛网。手术时应尽可能增加钛网与终板接触面积，多保留相邻终板，选用限制性钢板，尽量选择自体骨植骨，避免椎间过度撑开等。防止术后钛网沉陷。