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We investigated the demographic characteristics and risk factors of Korean patients with naÏve central or branch retinal vein occlusion (CRVO or BRVO). This study enrolled 41 clinical sites throughout Korea and included 557 consecutive patients with retinal vein occlusion (RVO) from May through November 2010. A total of 557 patients with new-onset RVO participated in this study. Two hundred and three (36.4%) patients were diagnosed with CRVO and 354 (63.6%) patients were diagnosed with BRVO. Comparisons between the two groups showed that the prevalence of diabetes mellitus was significantly higher in CRVO patients and hypertension was significantly higher in BRVO patients (P = 0.001 and 0.002, respectively). Poor baseline visual acuity was significantly associated with female and old age in BRVO patients (P = 0.002 and 0.013, respectively), whereas the wide intraretinal hemorrhage (CRVO, P = 0.029; BRVO, P < 0.001) and the macular ischemia (CRVO, P < 0.001; BRVO, P < 0.001) were associated with both groups. The study results show the clinical features of RVO in Korean patients. Hypertension is strongly associated with BRVO and diabetes mellitus is more strongly associated with CRVO in Korean patients with RVO. As the first nationwide study performed by the Korean Retinal Society, the results of this study can be applied to future studies on RVO.

We investigated the induction and underlying mechanism of apoptosis in retinal pigment epithelial cells by the inhibition of proteasome activity using lactacystin. Rat retinal pigment epithelial cell line retinal pigment epithelial (RPE)-J was used in this study. Apoptosis was evaluated by light and electron microscopies, DNA electrophoresis, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The apoptosis-related proteins were localized in the cells by immunofluorescent microscopy, and the changes of their protein contents and the enzyme activation were monitored by Western blot. Mitochondrial membrane potential was quantified by measuring J aggregate (5,5Ј,6,6Ј-tetrachloro-1,1Ј,3,3Ј-tetraethylbenzimidazol carbocyanine iodide) fluorescence. To measure changes in intracellular pH, cells were loaded with 2Ј,7Ј-bis(carboxyethyl)-5(6Ј)-carboxyfluorescein and assayed by flow cytometry. To elucidate the type of transport system involving intracellular pH regulation, several transporter inhibitors were used, and their effect on pH and membrane potential was assayed as described above. Lactacystin treatment significantly induced apoptosis in RPE-J cells. During the RPE cell apoptosis, 1) cytochrome c and Smac/DIABLO were released into cytosol from mitochondria, 2) translocation of apoptosis-inducing factor to the nucleus was evident, 3) Bax protein seemed to translocate to mitochondria, 4) procaspase-3 and poly(ADP-ribose) polymerase were cleaved, and 5) nuclear condensation and DNA fragmentation were clearly observed. Noticeably, a transient increase of mitochondrial membrane potential was coincidentally detected with the intracellular alkalinization after lactacystin administration. Furthermore, the lactacystin-induced early alkalinization was inhibited by 4-acetamido-4Ј-isothiocyanostilbene-2,2Ј-disulfonate, an inhibitor of Cl Ϫ /HCO 3 Ϫ anion exchanger, which also prevented early mitochondrial hyperpolarization and apoptosis. Lactacystin-induced apoptosis in RPE-J cells is closely associated with an early mitochondrial hyperpolarization induced by intracellular alkalinization.Apoptosis is an evolutionarily conserved, innate process by which cells systemically inactivate, disassemble, and degrade their own structural and functional components to complete their own demise (Wyllie et al., 1980). In this highly regulated process, a cascade of molecular and biochemical events leading to cell death is activated.Caspase activation is a central process in the execution of dying cells. The activation of an effector caspase, such as caspase-3, is stimulated by activated initiator caspases, caspase-8 or -9. Once activated, the effector caspases are responsible for the proteolytic degradation of a broad spectrum of cellular targets that ultimately leads to cell death (Thornberry and Lazebnik, 1998). However, the activation of effector caspases can be suppressed in the presence of inhibitors of apoptosis proteins (Roberts et al., 2001). Mitochondria play an important role in the regulation of apopto...

In addition to its well-characterized role in the lens, αB-crystallin performs other functions. Methylglyoxal (MGO) can alter the function of the basement membrane of retinal pigment epithelial (RPE) cells. Thus, if MGO is not efficiently detoxified, it can induce adverse reactions in RPE cells. In this study, we examined the mechanisms underlying the anti-apoptotic activity of αB-crystallin in the human retinal pigment epithelial cell line ARPE-19 following MGO treatment using various assays, including nuclear staining, flow cytometry, DNA electrophoresis, pulse field gel electrophoresis, western blot analysis, confocal microscopy and co-immunoprecipitation assays. To directly assess the role of phosphorylation of αB-crystallin, we used site-directed mutagenesis to convert relevant serine residues to alanine residues. Using these techniques, we demonstrated that MGO induces apoptosis in ARPE-19 cells. Silencing αB-crystallin sensitized ARPE-19 cells to MGO-induced apoptosis, indicating that αB-crystallin protects ARPE-19 cells from MGO-induced apoptosis. Furthermore, we found that αB-crystallin interacts with the caspase subtypes, caspase-2L, -2S, -3, -4, -7, -8, -9 and -12 in untreated control ARPE-19 cells and that MGO treatment caused the dissociation of these caspase subtypes from αB-crystallin; transfection of S19A, S45A or S59A mutants caused the depletion of αB-crystallin from the nuclei of untreated control RPE cells leading to the release of caspase subtypes. Additionally, transfection of these mutants enhanced MGO-induced apoptosis in ARPE-19 cells, indicating that phosphorylation of nuclear αB-crystallin on serine residues 19, 45 and 59 plays a pivotal role in preventing apoptosis in ARPE-19 cells. Taken together, these results suggest that αB-crystallin prevents caspase activation by physically interacting with caspase subtypes in the cytoplasm and nucleus, thereby protecting RPE cells from MGO-induced apoptosis.

This study investigated the baseline predictors of best corrected visual acuity (BCVA) and central retinal thickness (CRT) at 6 months in patients with treatment-naïve branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). This multicenter, interventional case series included 208 BRVO and 123 CRVO patients with follow-up period of 6 months or more. Outcome measures of BCVA (logMAR) included absolute change from baseline and a gain or loss of ≥ 0.3 from baseline. Outcome measures of CRT included absolute change from baseline and a measurement of ≤ 250 µm or ≥ 400 µm at 6 months. Univariate and multiple regression analyses were done to find baseline predictors. For BRVO, younger age, worse baseline BCVA, and shorter duration of symptom were associated with more gain in BCVA. For CRVO, worse baseline BCVA was associated with more gain in BCVA. For CRT outcomes, higher baseline CRT predicted greater decrease at 6 months in both BRVO and CRVO. Younger age and better baseline BCVA were associated with an increased likelihood of measurement of a ≤ 250 µm outcome for BRVO and CRVO, respectively. For CRVO, smoking was associated with greater decrease from baseline and decreased likelihood of measurement of a CRT ≥ 400 µm at 6 months. In conclusion, several baseline factors including age, symptom duration, and baseline BCVA and CRT are associated with BCVA and CRT outcomes at 6 months, which may help to predict disease course for RVO patients.Graphical Abstract