老年性白内障与微量元素

参阅有关老年性白内障的文献．归纳其病因有四种学说:(1)老化学说;(2)醌体学说;(3)微量元素学说;(4)中医学说．按病因学说不同．用药各异．目前治疗老年性白内障药物有滴眼剂及内服剂,其中有一种新药名为除障灵．它是根据中医学说及微量元素学说，筛选中药制成,它含有丰富的锌、硒、铜、镁等微量元素．应用除障灵治疗老年性白内障患者102例(204只眼)，观察6个月至2年，有效率达95％，开创了治疗老年性白内障的新方法．     

先天性白内障一家系的致病基因研究

目的 对一个来自浙江省杭州地区的三代先天性白内障家系进行常染色体显性遗传基因的突变分析,以寻找其可能的致病基因及突变位点。方法 该家系共10例成员,其中包括4例患者。10 例家系成员在浙江省人民医院眼科中心接受眼科专科检查及全身检查,以排除存在白内障以外的眼部及全身疾患。10例家系成员各抽取外周血5ml,提取基因组DNA。针对国内外文献报道的与常染色体显性遗传先天性白内障相关的18 个基因（CRYAA、CRYAB、CRYBA1、CRYBA2、CRYBA4、CRYBB1、CRYBB2、CRYGC、CRYGD、CRYGS、GJA3、GJA8、MIP、BFSP、HSF4、PITX3、EPHA2、PAX6）设计引物,进行PCR 扩增,对扩产物进行测序和序列分析,了解这10例家系成员的以上基因是否存在相应的序列。结果 临床眼科检查显示该家系先天性白内障类型为粉尘状白内障。候选基因序列测定显示在CRYAA 第1 个外显子中第6 位碱基发生C→T 置换,氨基酸同为天门冬氨酸。该家系中所有患者均有此改变,而所有的正常家系成员均无此改变。结论 CRYAA 第1个外显子中第6位碱基发生C→T的同义突变可能是导致该家系先天性白内障发生的致病原因。     

Development of cataract and corneal opacity in mice due to radon exposure

This work investigates the radiation damage on the eye of albino mice exposed to effective radon doses ranging from 20.92 to 83.68 mSv. These doses were taken over 2–8 weeks using a radon chamber constructed by the National Institute for Standard (Egypt). The guidance on the quality assurance program for radon measurements was followed. Therefore, the estimated doses received by the laboratory animals meet the requirements of national standard. The refractive index(RI) and protein concentration were measured for soluble proteins of both corneas and lenses. In addition, the sodium dodecyle sulfate polyacrylamide gel electrophoresis (SDSPAGE) technique was used. The results show increasing of the RI of both cornea and lens proteins and decreasing in total protein concentration of exposed animals. These results were accompanied with changes in the SDSPAGE profile for both cornea and lens. Therefore, radon exposure produces substantial hazards to the cornea and lens of experimental animals and has a crucial role in the development of cataract and corneal opacity.     

In vitro anti-cataract evaluation of standardised Abies pindrow leaf extract using isolated goat lenses

Oxidative stress is known to spark off the pathogenesis of cataract. Antioxidant potential of Abies pindrow Royle leaf extract (APE) is well established in the literature. In this context, standard aqueous leaf extract of this plant was evaluated for its role in hydrogen peroxide-induced cataract in isolated goat lenses using varying concentrations (5, 10, 15 and 20 mg/mL). Total phenol and flavonoidal content was evaluated and found to be high in concentration. Biochemical parameters, namely superoxide dismutase (SOD), glutathione (GSH), total protein content (TPC) and malondialdehyde (MDA), were evaluated. SOD, GSH and TPC formation was found to increase proportionally with increasing concentration. However, MDA level decreased significantly as the concentration of the extract increased. The results suggest that the extract under investigation can delay the onset and/or prevent the progression of cataract. Its anti-cataract potential may be attributed to the presence of high phenolics and flavonoids in APE. Photographic evaluation, further, confirmed the observation.     

A MELAS syndrome family harboring two mutations in mitochondrial genome

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a genetically heterogeneous mitochondrial disorder with variable clinical symptoms. Here, from the sequencing of the entire mitochondrial genome, we report a Korean MELAS family harboring two homoplasmic missense mutations, which were reported 9957T>C (Phe251Leu) transition mutation in the cytochrome c oxidase subunit 3 (COX3) gene and a novel 13849A>C (Asn505His) transversion mutation in the NADH dehydrogenase subunit 5 (ND5) gene. Neither of these mutations was found in 205 normal controls. Both mutations were identified from the proband and his mother, but not his father. The patients showed cataract symptom in addition to MELAS phenotype. We believe that the 9957T>C mutation is pathogenic, however, the 13849A>C mutation is of unclear significance. It is likely that the 13849A>C mutation might function as the secondary mutation which increase the expressivity of overlapping phenotypes of MELAS and cataract. This study also demonstrates the importance of full sequencing of mtDNA for the molecular genetic understanding of mitochondrial disorders.     

老年性白内障晶状体中金属元素的人工神经网分析

由Ｋ、Ｎａ，Ｃａ，Ｍｇ，Ｆｅ，Ｃｕ，Ｚｎ和Ｍｎ在老年性晶状体中的含量，运用人工神经网法成功地将老年性白内障，白内障晶状体核和正常人晶状体划分为３类，同时讨论了神经网的结构（层数及每层的结点数）、初始权重等对神经网性能的影响，随机地将３０个晶状体分为训练集和测试集，其识别率及预测率均达到１００％。     

Polymers for in vivo tuning of refractive properties in intraocular lenses

High-refractive-index polymers for intraocular lenses are presented whose refractive index can be tuned post-operatively in a non-invasive manner to enable focal length and aspheric corrections in vivo. The polymer materials contain covalently attached photochemically crosslinkable coumarin side groups, to cause a change in refractive index of Deltan > 0.02, which enables one to tune the focal length of a standard IOL by two diopters. This is enough to ensure that more than 80% of all cataract patients can be adjusted non-invasively to optimal vision after cataract surgery, thus providing a remedy to a major shortcoming of today's cataract surgery.     

Early Stage UV-B Induced Molecular Modifications of Human Eye Lens γD-Crystallin

In the human eye lenses, the crystallin proteins facilitate transparency, light refraction, as well as UV light protection. A deregulated balanced interplay between α-, β-, and γ-crystallin can cause cataract. γD-crystallin (hγD) is involved in the energy dissipation of absorbed UV light by energy transfer between aromatic side chains. Early UV-B induced damage of hγD with molecular resolution is studied by solution NMR and fluorescence spectroscopy. hγD modifications are restricted to Tyr 17 and Tyr 29 in the N-terminal domain, where a local unfolding of the hydrophobic core is observed. None of the tryptophan residues assisting fluorescence energy transfer is modified and hγD is remained soluble over month. Investigating isotope-labeled hγD surrounded by eye lens extracts from cataract patients reveals very week interactions of solvent-exposed side chains in the C-terminal hγD domain and some remaining photoprotective properties of the extracts. Hereditary E107A hγD found in the eye lens core of infants developing cataract shows under the here used conditions a thermodynamic stability comparable to the wild type but an increased sensitivity toward UV-B irradiation.     

微量元素硒对眼科疾病防治的研究进展

硒是人体必需微量营养元素,在人体代谢过程中参与多种代谢活动,参与维持眼睛正常的生理生化功能,微量元素硒缺乏会引起眼睛的生理生化功能紊乱,引起眼科疾病如老年性白内障等,适当补硒可以激活体液和细胞免疫调节能力.参考相关文献综述了硒的作用机制及其对眼科疾病防治的进展.     

Accumulation of argpyrimidine, a methylglyoxal-derived advanced glycation end product, increases apoptosis of lens epithelial cells both in vitro and in vivo

The formation of advanced glycation end products (AGEs) has been considered to be a potential causative factor of injury to lens epithelial cells (LECs). Damage of LECs is believed to contribute to cataract formation. The purpose of this study was to investigate the cytotoxic effect of AGEs on LECs both in vitro and in vivo. We examined the accumulation of argpyrimidine, a methylglyoxal-derived AGE, and the expression of apoptosis-related molecules including nuclear factor- kappaB (NF-κB), Bax, and Bcl-2 in the human LEC line HLE-B3 and in cataractous lenses of Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. In cataractous lenses from twenty-oneweek- old ZDF rats, LEC apoptosis was markedly increased, and the accumulation of argpyrimidine as well as subsequent activation of NF-κB in LECs were significantly enhanced. The ratio of Bax to Bcl-2 protein levels was also increased. In addition, the accumulation of argpyrimidine triggered apoptosis in methylglyoxal- treated HLE-B3 cells. However, the presence of pyridoxamine (an AGEs inhibitor) and pyrrolidine dithiocarbamate (a NF-κB inhibitor) prevented apoptosis in HLE-B3 cells through the inhibition of argpyrimidine formation and the blockage of NF-κB nuclear translocalization, respectively. These results suggest that the cellular accumulation of argpyrimidine in LECs is NF-κB-dependent and pro-apoptotic.