Calcium content and distribution in human cataract

The calcium content and distribution was measured in brunescent cataracts from India and cataracts from the United States classified according to guidelines of the Cooperative Cataract Research Group (CCRG). The severity and extent of opacification correlates well with the increase in Ca²⁺ bound to membranes and insoluble proteins separated by differential centrifugation. Thus, bound Ca²⁺ is approximately 30 ng/mg for the immature cataract. 100 ng/mg for the pale yellow. 200 ng/mg for the mature cataract and 300 ng/mg for the brown brunescent. These values can be compared to 16 ng/mg (0·2 mm) for a freshly excised rabbit lens.To the extent that the mature cataract represents an advanced stage and the immature cataract an early stage of development, and likewise for the brown and pale yellow cataract, results of this study suggest that cataract development is not accompanied by, or the result of, a redistribution of ‘free’ and bound calcium. We find that the fraction of total calcium bound to membranes and insoluble proteins is the same in the early and advanced stages of U.S. and Indian cataracts. It appears that as calcium accumulates in the developing cataract, an increasing amount becomes membrane or protein bound while the level of diffusible Ca²⁺ continues to increase. In the advanced stage as much as 85% of the calcium in the 10 000 g supernatant is dialyzable or diffusible. The remaining 15% is bound to watersoluble proteins and represents a sixfold to 15-fold increase in the mature and brown cataract, respectively. There is also a considerable increase in the amount of calcium found in the 1000 g pellet containing insoluble proteins and membrane fragments.     

The relationship between cataract,cell swelling and volume regulation

The cause of cataracts is not known. Data from epidemiological and case-control studies have suggested various risk factors, among them; sunlight, diabetes, diarrhoea, oxidative stress, smoking and alcohol. Many reports in the literature suggest that the hydrated state of the lens is linked to cataract and recently direct evidence has emerged linking lens swelling to cataract. This review attempts to collate the various strands of evidence relating the hydrated state of the lens in cataract and to construct a common pathway for cataractogenesis. This common pathway involves lens swelling, membrane permeabilization, vacuole and cleft formation, disturbance to the intracellular environment, protein aggregation/modification and light scatter. This hypothesis gives rise to some testable predictions amongst which is that under certain conditions the lens axial diameter will increase raising the possibility that pre-cataractous changes could be detected (e.g., by ultrasound) and, with appropriate action, the cataract could be prevented or delayed. There are encouraging signs from animal studies that certain types of lens opacification can be delayed or prevented, lending credibility to the objective of cataract prevention in humans. Even a delay in the onset of cataract would have a huge global impact.The incidence of cataract correlates with poverty, poor diet and poor hygiene and the vast majority of cataract is found in developing countries. Economic factors and a lack of cataract surgeons in these countries mean that surgery is not the long-term answer. Prevention is the only realistic global approach. This review concludes that detection of pre-cataractous changes and cataract prevention are achievable objectives and funds should be directed towards their realization.     

Endothelial cell density and corneal pachometry after no-stitch,small-incision cataract surgery

In a prospective study we used the change of central and peripheral (12 o'clock-position) corneal thickness (CT) after no-stitch small incision cataract surgery as a parameter of tissue traumatisation (33 eyes) and compared the values to a series of cases (32 eyes) with conventional 3.5 mm scleral step incision. In both groups the peripheral measurements showed a higher increase in corneal thickness than the central. After 1 month all eyes regained their central preoperative thickness. Increase in corneal thickness (ACTc, ACTp) after the different postoperative periods were correlated. The values of the central cornea showed no significant difference between the two groups. 1, 7 and 30 days after surgery the increase of peripheral CT was significantly higher in the no-stitch group. This fact was underlined by the clinical aspect at the slit lamp and is due to the anatomical and surgical characteristic of this procedure. One month postoperatively there was no increased endothelial cell loss in the no-stitch group (3%). No-stitch cataract surgery surgery provides a lot of intra- and postoperative advantages. The problem of increased swelling of the peripheral corneal entry seems to be a secondary one as corneal thickness decreases with time. Concerning the prospective endothelial cell loss it is mandatory to study the long term results.     

氧化性白内障晶状体中蛋白和细胞的改变

目的探讨将氧化性白内障动物作为模型研究人老年性白内障机制的可行性。方法用过氧化氢(H2O2)诱发大鼠晶状体产生白内障,分析晶状体相对灰度值、晶状体水化程度,Folin酚法测量水溶性蛋白(WSP),电泳及染色分析WSP条带,流式细胞术测定晶状体上皮细胞(LECs)凋亡。结果6、12和24h时晶状体相对灰度值减小(P<0.05);WSP比例减少(P<0.05);WSP的相对分子质量为25000、29000和30000的信号减弱;晶状体水化程度增加(P<0.01);凋亡LECs增加(P<0.01)。结论H2O2诱发大鼠晶状体产生的白内障,其蛋白和细胞的改变与人老年性白内障相似,将氧化性白内障动物作为模型研究人老年性白内障具可行性。     

Lens epithelial cell death after cataract surgery

PURPOSE: To determine whether lens epithelial cells (LECs) undergo apoptosis during healing after cataract surgery to further characterize the healing process of the postoperative lens capsule. SETTING: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. METHODS: Apoptotic cells were detected in human postoperative lens capsules using the terminal deoxynucleotidyl transferase deoxy-UTP nick-end labeling (TUNEL) method. The effect of exogenous transforming growth factor-beta2 (TGF-beta2) on mouse LEC apoptosis was also examined in an organ-culture system. RESULTS: Three of 17 postoperative specimens contained TUNEL-positive cells. In 2 lens capsules obtained earlier than 10 days, many TUNEL-positive cells, presumably apoptotic LECs, were observed beneath the residual anterior capsule. In cell multilayers in capsule opacification extracted later than 10 days, a few TUNEL-positive cells were seen in 1 specimen; most cells remained negative. In mouse lenses organ-cultured with 1.0 ng/mL TGF-beta2 for 48 hours, TUNEL-positive cells were detected beneath the lens capsule. CONCLUSIONS: Lens epithelial cells undergo apoptosis during healing after cataract surgery, especially in the early phase. Transforming growth factor-beta2 may be a factor inducing apoptosis in in vivo LECs.     

Schizophrenia, psychotropic medication, and cataract

OBJECTIVE: To compare the distribution of cataract types between psychiatric patients diagnosed with schizophrenia and the general population not exposed to psychotropic medication, and to compare cataract prevalence between users and nonusers of various psychotropic medications in the general community. DESIGN: Case-control. PARTICIPANTS: A total of 151 (93%) eligible patients from a community mental health service and 3271 (83%) eligible residents from the Melbourne Visual Impairment Project (VIP) were examined. MAIN OUTCOME MEASURES: All patients 40 years of age and older from a community mental health service and residents of nine randomly selected areas of Melbourne were eligible. Best-corrected distance visual acuity was determined using a 4-m logarithm of the minimum angle of resolution (LogMAR) chart. The presence of cataract was determined by photographs or slit-lamp examination using direct and indirect retroillumination. Anterior, cortical, nuclear, and posterior subcapsular cataracts were measured. Participants from the Melbourne VIP were classified as to whether they had taken benzodiazepams, phenothiazines, thioxanthenes, butyrophenols, tricyclic antidepressants, or monoamine oxidase inhibitors for at least 12 months during their lifetime. RESULTS: The distribution of cataract type varied between persons with and without schizophrenia. Anterior subcapsular (ASC) cataract was significantly more prevalent (26%) in participants with schizophrenia from the community mental health service than Melbourne VIP participants (0.2%) not exposed to psychotropic medication (chi-square, 1 degree of freedom = 605.5, P = 0.001). This remained significant after controlling for age (odds ratios = 250, 95% confidence interval = 83.3, 1000). The distribution of the age-related cataract was similar across all groups of psychotropic medication users with the exception of the phenothiazine users. They had less of all types of the age-related cataracts, despite being slightly older than the control group (mean age, 60.0 vs. 58.4, t test = 0.85, P = 0.40). However, only cortical cataract in the phenothiazine group was statistically lower (chi-square, 1 degree of freedom = 3.96, P = 0.047). CONCLUSION: This study has identified the need to investigate whether other newer agents, especially high-potency medications, cause ASC opacities if a certain threshold of exposure to psychotropic medications must be attained to develop cataract, or if schizophrenia itself is associated with cataract formation.     

Effects of age, sex, cataract, and cataract surgery on serum gamma-crystallin concentration.

PURPOSE: To determine if measurement of lens protein in serum is a feasible means to gain information on the physiologic status of the lens in human subjects. METHODS: The gamma-crystallin concentration was measured by a sandwich radioimmunoassay in the sera of 280 subjects aged 25-94 years. Medical records were reviewed for diagnoses of cataract and aphakia. RESULTS: There was no effect of age or sex on the serum gamma-crystallin concentration. There were 57 subjects with cataract and 27 with aphakia. gamma-Crystallin was higher in all cataract groups and lower in aphakia. The mean gamma-crystallin concentrations for selected subject groups were as follows: clear lens 301 pg/ml; pure nuclear cataract 344 pg/ml; pure cortical cataract 439 pg/ml and aphakia 255 pg/ml. CONCLUSIONS: This is the first published report to show that lens protein is measurable in serum and to demonstrate the feasibility of using serum assays of lens proteins to gain information on the physiological status of the lens. Our results confirm the hypothesis that molecular and cellular events leading to cataract cause increased leakiness of lens cell membranes with release of lens proteins appearing in the blood. It is conceivable that measurement of lens proteins in serum might find future use in the evaluation of cataract risk, potentially cataractogenic and anticataractogenic agents, retained lens fragments after phacoemulsification, secondary cataract, phacolytic glaucoma, anaphylactic endophthalmitis, eye injuries, and other eye diseases.     

晶体上皮细胞凋亡与白内障的形成

目的：探讨氧化损伤致晶体上皮细胞凋亡与白内障形成的关系。方法：离体家兔晶体于Ｍ１９９培养液中培养,实验组另加过氧化氢使其最后浓度为０．９ｍＭ,对照组不加过氧化氢。实验组与对照组均以不同时限分为３、６、１２、１８、２４、３６、４８、６０、８４、１０８小时１０个组。每组晶体６～９只。利用白色背景下黑色方格作为判断晶体混浊度的客观指标,其方法是透过晶体观察方格线的清晰度并拍照。利用ＴＵＮＥＬ技术检测晶体     

Cystinosis, cataract surgery, and corneal erosions

A 21-year-old man presented with severe corneal cystinosis and steroid-related cataract bilaterally. Rather than combined cataract surgery and penetrating keratoplasty, the patient had uneventful phacoemulsification and intraocular lens implantation after which visual acuity improved to 66 in both eyes. The outcome indicates that conventional phacoemulsification is sufficient in these cases. A guarded prognosis is advised in patients with cystinosis having cataract surgery as the fundal view is often impaired and there may be associated maculopathy.     

老年性白内障晶状体上皮细胞超微结构观察

目的 研究老年性白内障晶状体上皮细胞的超微结构,探讨老年性白内障与晶状体上皮细胞凋亡关系。方法 用透射电镜对20例老年白内障及10例正常透明晶状体上皮细胞的超微结构进行观察,拍照。结果 老年白内障组晶状体上皮细胞中发现了典型的凋亡小体,正常对照组未见凋亡细胞。结论 老年性白内障的发生与晶体上皮细胞的凋亡有关。     

老年性白内障晶狀體上皮細胞超微結構觀察

目的研究老年性白内障晶狀體上皮細胞的超微結構,探討老年性白内障舆晶狀體上皮細胞凋亡關系.方法用透射電鏡對20例老年白内障及10例正常透明晶狀體上皮細胞的超微結構進行觀察,拍照.結果老年白内障組晶狀體上皮細胞中發現了典型的凋亡小體,正常對照組未見凋亡細胞.結論老年性白内障的發生舆晶體上皮細胞的凋亡有關.     

细胞自噬在白内障形成过程中的研究进展

自噬(autophagy)是真核细胞中细胞器以及蛋白质等物质降解的主要过程,在维持体内平衡的过程中起到重要作用。人眼晶状体是一个由上皮细胞以及其分化而来的纤维细胞共同组成的无血管透明器官,晶状体细胞主要通过自噬途径来降解细胞器以及异常聚集的蛋白质以维持晶状体的透明。自噬功能的异常与白内障的发生发展密切相关。本文就自噬相关内容进行介绍,并概括总结了近年来细胞自噬在白内障形成过程中的研究进展。     

白内障晶状体上皮细胞Bcl-2Bax表达的增龄性研究

目的 探讨随着年龄的增长白内障晶状体上皮细胞Bcl-2、Bax的基因表达与白内障发生的关系,及其在白内障发生发展中的作用机制.方法 选取行超声乳化白内障手术的患者91例91只眼,取晶状体前囊膜.根据年龄分为3组,即Ⅰ组为≤30岁的患者11例,Ⅱ组为31～60岁的患者30例,Ⅲ组为≥61岁的患者50例.采用链霉菌亲生物素蛋白-过氧化物酶标免疫组织化学法(streptavidin-peroxidase,SP)染色,镜下检测三个不同年龄组白内障患者晶状体上皮细胞Bcl-2基因蛋白与Bax基因蛋白的表达情况.结果 Ⅰ、Ⅱ、Ⅲ组Bcl-2基因表达分别为89%、60%、0.5%,Bax基因表达分别为0、11%、91%.各项指标经统计学分析具有统计学意义(P<0.05).结论 随着年龄的增长白内障晶状体上皮细胞Bcl-2基因表达逐渐降低,Bax基因表达逐渐增高,为在基因水平上治疗白内障提供了理论依据.

Abstract：

Objective To evaluate the relationship between cataract lens epithelial cell and Bcl-2, Bax expression with increasing age in patients, and to investigate the role of Bcl-2 and Bax expression in the occurrence and progression of human lens epithelial cells of cataract.Methods Ninety-one patients (91 eyes) who were done phacoemulsification for cataract were selected and took anterior capsule of lens.The cataract patients were divided into three groups according to age: 11 cases of less than 30 years of age in group Ⅰ , 30 cases of aged 31-60 in group Ⅱ, 50 cases more than 61 years of age in group Ⅲ.The expression of Bcl-2 and Bax in lens epithelial cells of cataract from three different age groups of cataract patient was detected by the immunohistochemical streptavidin-peroxidase (SP) method.Results The Bcl-2 gene expression in group Ⅰ , Ⅱ, and Ⅲ was 89%, 60% and 0.5% respectively, the Bax gene expression was 0, 11% and 91% respectively.The difference had the statistical significance between 3 groups (P <0.05).Conclusions The genes expression of Bcl-2 in human lens epithelial cells of cataract is gradually decreasing with age increasing, while the genes expression of Bax is gradually increasing with age increasing.It provides an important theoretical basis to treat of cataract at the gene level.