Lou M F, Dickerson J E, Tung W H, Wolfe J K, Chylack L T
Dept. of Ophthalmology, University of Nebraska, Lincoln, NE, 68583 and, USA.
Exp Eye Res. 1999 May;68(5):547-52. doi: 10.1006/exer.1998.0638.
Human lens nuclei were collected during routine cataract surgery and used to study the role of oxidation in cataract formation and brunescence. This study focused on the comparison of the intensities of nuclear opacity and pigmentation (brunescence) with the changes in free glutathione (GSH) and the three species of protein-thiol mixed disulfides: protein-S-S-glutathione (PSSG), protein-S S-cysteine (PSSC) and protein-S-S-gamma-glutamylcysteine (PSSGC). Eighty-one freshly excised human lens nuclei from a population with a mean age of 77 were used. The nuclear color was graded using the CCRG system, ranging from yellow to dark brown. The nuclear cataract opalescence of these lenses was also graded using the LOCS II system, ranging from LOCS II NO-1 to NO-4. Three normal human lenses (average age of 88 yr) were also included in the study as controls. The nuclear samples were each analyzed for free GSH and protein-thiol mixed disulfides, respectively. It was found that nuclear GSH decreased as the nuclear color increased from yellow to dark brown (from 0.73+/-0.13 to 0.13+/-0.03 micromole g wet wt-1) and as the nuclear opalescence increased from NO.1 to NO.4 (from 0. 80+/-0.19 to 0.20+/-0.01 micromole g wet wt-1). All these values were lower than that of GSH in normal controls (1.43+/-0.59 micromole g wet wt-1). Levels of both PSSG and PSSC progressively increased, however, as the nuclear color intensified. PSSG increased from 0.29+/-0.05 to 0.91+/-0.11 micromole g wet wt-1while PSSC increased from 0.13+/-0.04 to 0.41+/- 0.06 micromole g wet wt-1. PSSGC concentration progressively increased with increases in both nuclear pigmentation (from 0.05+/-0.01 to 0.23+/-0.05 micromole g wet wt-1) and nuclear opacity (from 0.02+/-0.00 to 0.20+/-0.02 micromole g wet wt-1). In comparison, normal controls had lower levels of all three mixed disulfide species: PSSG, 0.22+/-0.06; PSSC, 0.08+/-0.02; PSSGC, 0.02+/-0.06 micromole g wet wt-1, respectively. The correlation of lens nuclear color and opalescence intensity with nuclear protein S-thiolation indicates that protein-thiol mixed disulfides may play an important role in cataractogenesis and development of brunescence in human lenses.
在常规白内障手术过程中收集人晶状体核，用于研究氧化在白内障形成和晶状体棕黄色化中的作用。本研究着重比较核不透明度和色素沉着（晶状体棕黄色化）的强度与游离谷胱甘肽（GSH）以及三种蛋白质 - 硫醇混合二硫化物：蛋白质 - S - S - 谷胱甘肽（PSSG）、蛋白质 - S - S - 半胱氨酸（PSSC）和蛋白质 - S - S - γ - 谷氨酰半胱氨酸（PSSGC）变化之间的关系。使用了来自平均年龄为77岁人群的81个新鲜切除的人晶状体核。核颜色采用CCRG系统分级，从黄色到深棕色。这些晶状体的核性白内障浑浊度也采用LOCS II系统分级，从LOCS II NO - 1到NO - 4。研究还纳入了3个正常人类晶状体（平均年龄88岁）作为对照。分别对核样本进行游离GSH和蛋白质 - 硫醇混合二硫化物分析。结果发现，随着核颜色从黄色加深至深棕色（从0.73±0.13降至0.13±0.03微摩尔/克湿重-1）以及核浑浊度从NO.1增加到NO.4（从0.80±0.19降至0.20±0.01微摩尔/克湿重-1），核GSH含量下降。所有这些值均低于正常对照组的GSH水平（1.43±0.59微摩尔/克湿重-1）。然而，随着核颜色加深，PSSG和PSSC的水平均逐渐升高。PSSG从0.29±0.05升至0.91±0.11微摩尔/克湿重-1，而PSSC从0.13±0.04升至0.41±0.06微摩尔/克湿重-1。PSSGC浓度随着核色素沉着（从0.05±0.01升至0.23±0.05微摩尔/克湿重-1）和核不透明度（从0.02±0.00升至0.20±0.02微摩尔/克湿重-1）的增加而逐渐升高。相比之下，正常对照组中所有三种混合二硫化物的水平均较低：PSSG为0.22±0.06；PSSC为0.08±0.02；PSSGC为0.02±0.06微摩尔/克湿重-1。晶状体核颜色和浑浊度强度与核蛋白硫醇化的相关性表明，蛋白质 - 硫醇混合二硫化物可能在人类晶状体白内障发生和晶状体棕黄色化发展中起重要作用。
