Ultrastructural analysis of damage to nuclear fiber cell membranes in advanced age-related cataracts from India
Ultrastructural analysis of damage to nuclear fiber cell membranes in advanced age-related cataracts from India
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DOI：
10.1016/j.exer.2008.05.009
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发表时间：
2008-08-01
影响因子：
3.4
通讯作者：
Balasubramanian, Dorairajan
中科院分区：
文献类型：
--
作者：
Costello, M. J.;Johnsen, Soenke;Balasubramanian, Dorairajan
主要目的是表征在印度通过囊外白内障手术摘除的完全不透明白内障的核中纤维细胞界面处发生的结构改变。暗黄色到褐色的核，年龄38 - 78岁，可能是晚期年龄相关性核性白内障的代表。将厚组织切片固定，整块染色并包埋用于透射电子显微镜。染色的薄切片包含保存良好的膜和连接，尽管复杂的细胞拓扑结构通常需要广泛倾斜网格以可视化膜。在细胞核的所有区域均观察到纤维细胞膜的损伤。最重要的损伤发生在起伏的膜连接处，其中膜段的损失是常见的。这些膜断裂不是融合位点，因为检测到膜边缘，细胞质似乎与细胞外空间接触，细胞外空间在许多区域扩大。在细胞外间隙内经常观察到蛋白样物质的致密沉积，似乎与邻近细胞质中的蛋白相似。沉积物通常为20 - 50 nm厚，长度可变，位于质膜上的特定部位和细胞簇或细胞突起之间。此外，在细胞外间隙内观察到低密度区域，特别是在高度起伏的膜内，其中观察到直径约100 nm的间隙。与老年透明供体晶状体相比，膜损伤更广泛，细胞外间隙更大。由于高密度和低密度区域对折射率波动的贡献相等，因此基于理论分析，由于膜附近观察到的损伤而导致的密度变化可能产生显著的光散射。在20 - 100圈范围内的波动的尺寸意味着散射可能类似于小颗粒的散射，这将增加在裂隙灯中可见的高角度散射。随着白内障的成熟，这种对膜的损伤预计会导致核的完全混浊。波动的主要来源似乎是膜和邻近的细胞质蛋白的降解，以及蛋白质和片段的重新分布。(C)2008爱思唯尔有限公司保留所有权利。
The primary goal was to characterize the Structural alterations that occur at the fiber cell interfaces in nuclei of fully opaque cataracts removed by extracapsular cataract surgery in India. The dark yellow to brunescent nuclei, ages 38-78 years, were probably representative of advanced age-related nuclear cataracts. Thick tissue slices were fixed, en bloc stained and embedded for transmission electron microscopy. Stained thin sections contained well-preserved membranes and junctions, although the complex cellular topology often made it necessary to tilt the grid extensively to visualize the membranes. Damage to the fiber cell membranes was noted in all regions of the nucleus. The most important damage occurred within undulating membrane junctions where the loss of membrane segments was common. These membrane breaks were not sites of fusion as membrane edges were detected and cytoplasm appeared to be in contact with extracellular space, which was enlarged in many regions. Dense deposits Of protein-like material were frequently observed within the extracellular space and appeared to be similar to protein in the adjacent cytoplasm. The deposits were often 20-50 nm thick, variable in length and located on specific sites on plasma membranes and between clusters of cells or cell processes. In addition, low density regions were seen within the extracellular space, especially within highly undulating membranes where spaces about 100 nm in diameter were observed. The membrane damage was more extensive and extracellular spaces were larger than in aged transparent donor lenses. Because high and low density regions contribute equally to the fluctuations in refractive index, the changes in density due to the observed damage near membranes are likely to produce significant light scattering based on theoretical analysis. The dimensions of the fluctuations in the range 20-100 turn imply that the scattering is probably similar to that of small particles that Would increase high-angle scattering visible in the slit lamp. Such damage to membranes would be expected to contribute to the total opacification of the nucleus as the cataract matures. The main sources of the fluctuations appear to be the degradation of membranes and adjacent cytoplasmic proteins, as well as the redistribution of proteins and fragments. (C) 2008 Elsevier Ltd. All rights reserved.