【目的】探讨准分子激光原位角膜磨镶术(LASIK)前后角膜非球面特点及其对术后视觉质量的影响。【方法】前瞻性对本中心接受LASIK患者26例50眼进行随访研究,检测指标包括OrbscanⅡz角膜地形图(提供角膜非球面因子Q值)、波前像差、对比敏感度(contrast-sensitivity function,CSF)、裸眼视力、最佳矫正视力、最佳矫正球镜度;分析时段为术前及术后3月,分析手术前后角膜非球面因子Q值分布,Q值与高阶像差以及高阶像差与对比敏感度的关系。【结果】术前Q值为-0.17±0.11;术后Q值为0.84±0.41,两者存在统计学差异(P=0.01)。术前Q值与术前球差成负相关(P=0.000,r=-0.578),与高阶像差成正相关(P=0.047,r=-0.333)。手术前后Q值改变与球差改变成负相关(P=0.000,r=-0.588),与高阶像差改变成正相关(P=0.001,r=0.566)。术后3月无眩光、低、中、高度眩光对比敏感度均较术前降低,但无统计学差异(P>0.05)。高阶像差改变与术后无眩光各空间频率对比敏感度6.3,4.0,2.5,1.6,1.0,0.7(cycles per degree,cpd)成负相关(P<0.05);高阶像差改变与低、中、高度眩光对比敏感度中高频空间频率6.3,4.0,2.5,1.6cpd成负相关(P<0.05),与低频空间频率(1.0,0.7cpd)无相关关系(P>0.05)。【结论】近视性LASIK使角膜由伸长型(长椭球体)椭球体演变为扁平型椭球体(扁椭球体),并影响术后视觉质量。
目的 探讨老年痴呆症 ( AD)患者大脑中 ,大量神经元烟碱型胆碱能受体 ( n ACh Rs)丢失是否与 β-淀粉样多肽 ( Aβ)沉淀的关系及其影响 n ACh Rs表达的机制 ,建立一种老年性痴呆早期研究离体模型。方法 采用MTT、Annexin- V、配体结合实验以及 Western Blot、RPA法 ,观察 PC12细胞在 Aβ侵害早期 ,细胞损伤机制。结果 显示用纳摩尔浓度 Aβ1 - 40 能明显降低 PC12细胞 [1 2 5I]α- Bungarotoxin和 [3H]Epibatidine结合位点数量 ,引起 α3、α7和 β2亚单位蛋白和 α3、α7m RNA水平的下降 ,但不诱导凋亡 ,却明显抑制 MTT。结论 Aβ引起的 n ACh Rs生物合成降低 ,可能部分归因于细胞内在信号传导系统。本研究提示 ,在 AD病程早期大量 Aβ纤维形成之前 ,Aβ可直接引起 n Ach Rs退行性改变。应用药物修复 n ACh Rs,干预 Aβ对 n ACh R,尤其是对 α7n ACh R的毒性作用是预防和治疗
The TiO2 thin films were prepared on the surface of soda lime glass via sol gel method, and calcined at 500℃ for 2h. The as calcined TiO2 thin films were treated in 1mol·L-1 H2SO4 aqueous solution for 24h, after that the thin films were heat treated at 100℃ and 500℃ for 0.5h, respectively. The structures and photocatalytic activity of TiO2 thin films before and after surface acid treatment were characterized and evaluated by UV Vis, SEM, TEM and XPS and photocatalytic decoloration of methyl orange aqueous solution, respectively. It was found that after TiO2 thin films were treated in H2SO4 solution and calcined at 100℃ and 500℃, the content of sodium ions in the TiO2 thin films decreases and the photocatalytic activity of the thin films increases obviously. Moreover, the films show the highest photocatalytic activity at 500℃.
