SERUM LEVELS OF ANTIBODIES AGAINST OXIDATION-SPECIFIC EPITOPES ARE DECREASED IN PATIENTS WITH RETINAL VEIN OCCLUSION.

PURPOSE: Oxidative stress and inflammation have been implicated in the development of retinal vein occlusion (RVO). Oxidation-specific epitopes (OSEs) represent products of oxidative stress that can trigger vascular inflammation and thrombosis. Natural occurring antibodies have been shown to bind oxidation-specific epitopes thereby inhibiting their inflammatory potential and promoting their removal. METHODS: This prospective cross-sectional study included 270 patients with RVO and 81 in-hospital control patients. We measured three types of serum levels of oxidation-specific epitope-specific immunoglobulin M and immunoglobulin G antibodies (anti-copper-oxidized LDL [CuOx-LDL], antiphosphocholine [PC], anti-malondialdehyde-modified LDL [MDA-LDL]). History of arterial hypertension, hyperlipidemia, myocardial infarction, diabetes mellitus, stroke, smoking status, and several laboratory parameters were determined to control for potential confounders. RESULTS: Compared with controls, patients with RVO had significantly lower levels of immunoglobulin M and immunoglobulin G antibodies against CuOx-LDL and PC, and significantly lower levels of immunoglobulin G but not immunoglobulin M antibodies against MDA-LDL. The association between RVO patients and lower levels of these antibodies prevailed upon multivariable adjustment. CONCLUSION: These prospective data show that antibodies against oxidation-specific epitope are lower in patients with RVO compared with control patients and support the concept that oxidative stress and inflammation play key roles in the development and subsequent complications in RVO.

Change in cardiac troponin T level after intravitreal anti-vascular endothelial growth factor treatment: Prospective pilot study.

BACKGROUND: Evaluate subclinical myocardial injury associated with intravitreal anti-vascular endothelial growth factor therapy by measuring serum high-sensitivity cardiac troponin T. METHODS: This is a prospective pilot comparative study conducted at American University of Beirut Medical Center, Beirut, Lebanon. In total, 40 consecutive patients were randomized to receive either intravitreal bevacizumab or ranibizumab. Patients received three consecutive monthly injections of the assigned drug, then continued treatment as needed. Systemic concentrations of high-sensitivity cardiac troponin T and vascular endothelial growth factor were obtained at baseline, week 9, and week 24. Primary endpoint measure was change in high-sensitivity cardiac troponin T levels compared to baseline. Secondary endpoint measure was change in systemic vascular endothelial growth factor levels. RESULTS: There was no significant difference in high-sensitivity cardiac troponin T levels over time (p = 0.227) within each treatment group and no significant difference between treatments at any time point (p = 0.276). There was a significant decrease in plasma vascular endothelial growth factor levels at week 9 (p = 0.001) and week 24 (p < 0.001) compared to baseline. In the ranibizumab group, vascular endothelial growth factor levels were not significantly different at weeks 9 and 24 compared to baseline (p = 0.708 and p = 0.117, respectively). There was a significant association between the number of bevacizumab injections from weeks 8 to 24 and the decrease in vascular endothelial growth factor levels at week 24 (R = -0.67, p = 0.032). This correlation was not observed in the ranibizumab group (R = -0.341, p = 0.141). CONCLUSION: Repeated intravitreal bevacizumab or ranibizumab did not influence serum high-sensitivity cardiac troponin levels. Intravitreal bevacizumab but not ranibizumab lowered free-systemic vascular endothelial growth factor levels, which was observed in this study to be inversely related to the number of bevacizumab injections.

Retinal Vein Occlusion is Associated with Low Blood High-Density Lipoprotein Cholesterol: A Nationwide Cohort Study.

PURPOSE: To investigate association between the development of retinal vein occlusion (RVO) and blood high-density lipoprotein cholesterol (HDL-C). DESIGN: A retrospective, nationwide, population-based cohort study. METHODS: This study was set in the Republic of Korea and included 23,149,403 people ≥20 years of age who underwent the Korean National Health Screening Program examination between January 2009 and December 2012. Among them, the RVO group was composed of patients with an initial diagnosis of RVO made between 2009 and 2015 (n = 117,639). The earliest claim with an RVO diagnostic code was considered as the incident time. The predictive value of HDL-C level for RVO was analyzed using hazard ratios. The primary outcome measure was the incident cases of RVO. RESULTS: Subjects with RVO were generally older; had high body mass index, waist circumference, fasting blood glucose, blood pressure, total and low-density lipoprotein cholesterol, and triglyceride values, and low glomerular filtration rate and HDL-C values; and were more likely to experience diabetes mellitus and hypertension compared with the non-RVO group. The fully adjusted hazard ratio of RVO was 1.12 (95% confidence interval 1.10-1.14) in the lowest quartile of HDL-C versus in the highest quartile. The association between the development of RVO and HDL-C was higher those with a younger age, male sex, current smoking habit, diabetes mellitus, and hypercholesterolemia. In addition, we observed a significant synergistic effect of low HDL-C level with obesity and hypertension. CONCLUSION: This is the first nationwide population-based epidemiologic study evaluating the association between HDL-C level and the risk of RVO development. A significant association between low HDL-C and RVO development was found.

Platelet activation by ADP is increased in selected patients with anterior ischemic optic neuropathy or retinal vein occlusion.

To investigate whether adenosine diphosphate (ADP)-induced platelet hyperaggregability is associated with nonarteritic anterior ischemic optic neuropathy (NAION) or retinal vein occlusion (RVO). We retrospectively reviewed thrombophilia screening data of patients with NAION or RVO without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse. Patients with a positive family history for thromboembolism were not excluded. Platelet aggregation (area under the curve, AUC) after induction of 0.5, 1.0, and 2.0 µmol of ADP was estimated in 25 NAION and RVO patients and compared with 25 healthy controls. We observed significantly greater platelet aggregation post 0.5 (P = 0.002) and 1.0 (P = 0.008) µmol of ADP among NAION and RVO patients compared with healthy controls. Platelet hyperaggregability was significantly more prevalent in patients than in controls (56% vs. 8%; P = 0.0006). Our results suggest that in NAION and RVO patients without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse, platelets are significantly hyperreactive after induction of very low concentrations of ADP when compared with healthy individuals. This hyperreactivity is particularly evident in patients with a family history of thromboembolism.

Influence of hemorheological factors on the development of retinal vein occlusion.

OBJECTIVE: The aim of this article was to present the influence of hemorheological factors on appearance of Retinal Vein Occlusion (RVO). Article explains which factors predispose to the occurrence of RVO. STUDY SELECTION: Data presented in the article were collected from both review articles and research articles as well as other sources concerning hemorheology, pharmacology and ophthalmology. RESULTS: Appearance of RVO is connected with blood viscosity and hemorheological parametres like aggregation of red blood cells, deformability of red blood cells, fibrinogen concentrations and haematocrit, and platelet activity. In the pathogenesis of retinal vein occlusion other risk factors were also indicated: age, systemic diseases and smoking. Such correlation has been indicated in numerous researches which were conducted over the last years. RVO is usually accompanied by macular oedema. RVO may successfully be treated using intravitreal dexamethasone implant. CONCLUSION: Quick diagnosis and therapy create a possibility for successful treatment. Corticosteroid positive influence on visual acuity improvement has been indicted in two randomized, double-blind controlled studies - CRUISE and BRAVO. In both studies, the improvement of vision has been accompanied by a significant reduction of oedema in the vicinity of macula, reflected in the central retinal thickness.

Retinal vascular oximetry during ranibizumab treatment of central retinal vein occlusion.

PURPOSE: To investigate the effect of intravitreal injections of the vascular endothelial growth factor inhibitor ranibizumab on retinal oxygenation in patients with central retinal vein occlusion (CRVO). METHODS: Retinal oxygen saturation in patients with CRVO was analysed using the Oxymap Retinal Oximeter P3, before and during 6 months of treatment with intravitreal injections of ranibizumab. RESULTS: At presentation, retinal venous oxygen saturation was lower in eyes with CRVO than in the healthy fellow eyes (32±13% vs 59±10%, respectively, p=0.001) whereas retinal arterial saturation was higher in eyes with CRVO than in the fellow eyes (95%±8% and 91%±3%, p=0.04). Mean visual acuity increased from 51±24 letters ETDRS at baseline to 66±24 and 69±20 letters ETRDS, respectively, at 3 months and 6 months treatment (mean±SD, p<0.0001, repeated measures analysis of variance) and central retinal thickness was reduced from 697±139 µm to 368±113 µm and 340±96 µm, respectively, from baseline to 3 months and 6 months treatment (p<0.0001). Venous saturation increased during treatment (from 35.5%±13.8% at baseline to 43.1%±10.8% and 43.5%±13.7% after 3 months and 6 months treatment, respectively, p=0.012), while no significant change was found in arterial saturation (p=0.24). CONCLUSIONS: Retinal venous oxygen saturation was markedly reduced in untreated CRVO and was roughly halfway normalised during intravitreal ranibizumab treatment. Retinal artery oxygen saturation was not reduced in CRVO. TRIAL REGISTRATION NUMBER: NCT01360385.

Plasma homocysteine in patients with retinal vein occlusion.

PURPOSE: To evaluate total plasma homocysteine (HCY) during fasting and post methionine load test (MLT), serum folate, serum vitamin B12, and methylenetetrahydrofolate reductase (MTHFR) mutation in patients with retinal vein occlusion (RVO) and to examine the association between these risk factors and 2 subtypes of RVO: central (CRVO) and branch (BRVO). METHODS: This case-control study included 91 Italian patients presenting a first RVO and 71 healthy subjects, matched by age, without history of thromboembolic diseases, glaucoma, or malignancy. Homocysteine fasting and after MLT, serum folate level, serum vitamin B12 level, and other laboratory tests were assessed. Genetic analysis for the C677T MTHFR mutation was performed. RESULTS: Multivariate logistic regression analysis indicated that hypertension (odds ratio [OR] 2.63; 95% confidence interval [CI] 1.30-5.30; p = 0.007), higher values of fasting HCY (OR 1.16; 95% CI 1.01-1.33; p = 0.03), and low concentrations of vitamin B12 (OR 0.99; 95% CI 0.995-0.999; p = 0.01) were independently correlated with RVO. Moreover, the main determinants for CRVO risk were hypertension (OR 2.46; 95% CI 1.06-5.72; p = 0.04), high values of fasting HCY (OR 1.20; 95% CI 1.02-1.41; p = 0.03), and low concentrations of vitamin B12 (OR 0.99; 95% CI 0.994-0.999; p = 0.008), whereas for BRVO risk only hypertension was significant (OR 2.74; 95% CI 1.24-6.03; p = 0.01). Genotype distribution of the MTHFR C677T mutation did not reveal any significant difference between patients and controls. CONCLUSIONS: These results suggest that elevated fasting HCY levels, low vitamin B12 levels, and hypertension are associated with a risk of RVO, especially for CRVO. Moreover, our data suggest that only hypertension is associated with BRVO risk.

Molecular basis of erythrocyte adhesion to endothelial cells in diseases.

Red blood cell (RBC) adhesion to endothelium can be studied in static and flow conditions. Increased RBC adhesion was first described in sickle cell disease. Several molecules were shown to be involved in this phenomenon: VCAM-1, α4ß1, Lu/BCAM, ICAM-4. In malaria, Plasmodium falciparum erythrocyte membrane protein1 binds to ICAM-1, PECAM-1 and facilitates the parasite dissemination. In diabetes mellitus augmented RBC adhesion is correlated to the severity of vascular complications. Glycated RBC band3 reacts with the endothelial Receptor for Advanced Glycation End products (RAGE). RAGE engagement induced endothelial cell dysfunction. In patients with Polycythemia Vera (PV), the most frequent myeloproliferative disorder, constitutive phosphorylation of RBC Lu/BCAM is responsible for an increased adhesion to endothelial cell laminin. Retinal vein occlusion (RVO) is a common cause of permanent visual loss. Spontaneous growth of erythroid precursors was observed in more than 25% of patients. RBC adhesion was enhanced and correlated to phosphatidyl serine (PS) expression on RBC. Anti-PS receptor blocked RVO RBC adhesion indicating that the counterpart of RBC PS is PS endothelial cell receptor. Erythrocyte adhesion is mediated by different molecule abnormalities in different diseases but is associated to a higher risk of thrombosis and vascular complications.

Red blood cell phosphatidylserine exposure is responsible for increased erythrocyte adhesion to endothelium in central retinal vein occlusion.

BACKGROUND: Retinal vein occlusion (RVO) is a common cause of permanent loss of vision. The pathophysiology is uncertain, although enhanced erythrocyte aggregation and blood hyperviscosity have been observed. Increased red blood cell (RBC) adhesion has been associated with vascular complications in several diseases, such as sickle cell anemia, diabetes mellitus or polycythemia vera. OBJECTIVES: To measure RBC adhesion to endothelial cells in RVO and to explore the molecular basis of the adhesion process. PATIENTS AND METHODS: We assessed RBC adhesion to endothelial cells and adhesion molecule expression among 32 patients with RVO. Patients with disease known to alter RBC adhesion were excluded (n = 8), and further investigation was conducted in 20 patients with central retinal vein occlusion (CRVO) and four patients with retinal artery occlusion (RAO), compared with 25 normal subjects. RESULTS: Under static conditions, adhesion of CRVO RBC was increased (135 ± 7 × 10(2) mm(-2)) compared with RAO RBC (63 ± 5 × 10(2) mm(-2)) (P < 0.01) and normal control RBC (37 ± 3 × 10(2) mm(-2)) (P < 0.001). Under flow conditions, CRVO RBC adhered in greater numbers than normal RBC (P < 0.001). Phosphatidylserine (PS) expression on CRVO RBC was 2.4-fold higher than controls and correlated with RBC adhesion (P = 0.001). In static conditions, specific antibodies against PS receptor and annexin V inhibited RBC adhesion. In flow conditions, the inhibitory effect was in the same range with antibodies but was 2-fold higher with annexin V. CONCLUSION: Increased CRVO RBC adhesion is mediated by PS RBC and endothelial PS receptor. This phenomenon may be one of the factors responsible for CRVO.

Plasma thiols and taurine levels in central retinal vein occlusion.

PURPOSE: To determine the plasma levels of the sulfur-containing amino-acids homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in patients with central retinal vein occlusion (CRVO) and in healthy subjects and to ascertain whether there are statistically significant differences between patients and controls. METHODS: Laser-induced fluorescence capillary electrophoresis was used to measure the plasma levels of homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in 29 patients with CRVO and 80 age- and gender-matched control subjects. Wilcoxon or Student's t-test was used, when appropriate, to determine differences between groups. Multivariate logistic regression analysis was used to determine the risks for CRVO. RESULTS: CRVO patients showed significantly higher concentrations of cysteine (p = 0.032) and significantly lower concentrations of cysteinylglycine (p = 0.009) and taurine (p = 0.0002) than controls. Conversely, there were no significant differences in plasma homocysteine, glutamylcysteine, and glutathione between CRVO patients and controls. When categorized by CRVO type (ischemic/non-ischemic), taurine was still lower in both subgroups than in controls, whereas cysteine, cysteinylglycine, as well as homocysteine, were significantly higher only in the ischemic subgroup. In non-ischemic CRVO, cysteinylglycine fell just short of statistical significance (p = 0.06). Logistic regression analysis revealed an odds ratio of 1.02 (95% confidence interval (CI): 1.01-1.04, p = 0.001) for cysteine, 0.79 (95% CI: 0.70-0.89, p = 0.0002) for cysteinylglycine, and 0.94 (95% CI: 0.90-0.97, p = 0.002) for taurine. CONCLUSIONS: Results suggest that reduced plasma levels of cysteinylglycine and taurine may contribute to the pathogenesis of both CRVO types. Furthermore, this study also demonstrated an association between ischemic CRVO and higher concentrations of homocysteine and cysteine.

Decreased plasma cysteinylglycine and taurine levels in branch retinal vein occlusion.

PURPOSE: Our aim was to determine the plasma levels of the sulfur-containing amino acids homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione and taurine in patients with branch retinal vein occlusion (BRVO) and in healthy subjects and to ascertain whether there are statistically significant differences between patients and controls. METHODS: Homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione and taurine plasma levels were measured in 40 patients with BRVO and 80 age- and gender-matched control subjects by using laser-induced fluorescence capillary electrophoresis methods. Wilcoxon's or Student's t test was used, when appropriate, to determine differences between the groups. Conditional logistic regression analysis was performed to determine the risk factors for BRVO. RESULTS: BRVO patients showed significantly lower plasma concentrations of cysteinylglycine (p = 0.02) and taurine (p < 0.0001) than controls. Conversely, there were no significant differences in plasma homocysteine, cysteine, glutamylcysteine and glutathione between patients with BRVO and controls. Conditional logistic regression analysis revealed an odds ratio of 0.95 (95% confidence interval: 0.92-0.98, p = 0.001) for taurine and 0.86 (95% confidence interval: 0.78-0.96, p = 0.006) for cysteinylglycine. CONCLUSIONS: This study failed to demonstrate an association between BRVO and the plasma levels of homocysteine, cysteine, glutamylcysteine and glutathione. Cysteinylglycine and taurine were significantly lower in BRVO patients, thus suggesting that reduced plasma levels of these sulfur-containing amino acids may contribute to the pathogenesis of BRVO.

Comprehensive analysis of inflammatory immune mediators in vitreoretinal diseases.

Inflammation affects the formation and the progression of various vitreoretinal diseases. We performed a comprehensive analysis of inflammatory immune mediators in the vitreous fluids from total of 345 patients with diabetic macular edema (DME, n = 92), proliferative diabetic retinopathy (PDR, n = 147), branch retinal vein occlusion (BRVO, n = 30), central retinal vein occlusion (CRVO, n = 13) and rhegmatogenous retinal detachment (RRD, n = 63). As a control, we selected a total of 83 patients with either idiopathic macular hole (MH) or idiopathic epiretinal membrane (ERM) that were free of major pathogenic intraocular changes, such as ischemic retina and proliferative membranes. The concentrations of 20 soluble factors (nine cytokines, six chemokines, and five growth factors) were measured simultaneously by multiplex bead analysis system. Out of 20 soluble factors, three factors: interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) were significantly elevated in all groups of vitreoretinal diseases (DME, PDR, BRVO, CRVO, and RRD) compared with control group. According to the correlation analysis in the individual patient's level, these three factors that were simultaneously increased, did not show any independent upregulation in all the examined diseases. Vascular endothelial growth factor (VEGF) was significantly elevated in patients with PDR and CRVO. In PDR patients, the elevation of VEGF was significantly correlated with the three factors: IL-6, IL-8, and MCP-1, while no significant correlation was observed in CRVO patients. In conclusion, multiplex bead system enabled a comprehensive soluble factor analysis in vitreous fluid derived from variety of patients. Major three factors: IL-6, IL-8, and MCP-1 were strongly correlated with each other indicating a common pathway involved in inflammation process in vitreoretinal diseases.

Vitreous levels of erythropoietin in patients with macular oedema secondary to retinal vein occlusions: a comparative study with diabetic macular oedema.

OBJECTIVE: In a recent study, we found high levels of erythropoietin (EPO) in patients with diabetic macular oedema (DME), suggesting a role of EPO in the pathogenesis of this condition. To investigate a possible relationship between EPO and other diseases causing macular oedema, we determined vitreous levels of this peptide in patients with macular oedema secondary to retinal vein occlusion (RVO) and compared them with levels in patients with DME and control patients. METHODS: Vitreous and serum samples were obtained from patients with macular oedema secondary to RVO, DME, epiretinal membrane, and macular hole (controls). EPO was measured by radioimmunoassay. RESULTS: No differences were found in median vitreous EPO levels between patients with RVO and controls: RVO, 76 mU/ml (30-806) vs controls, 25 mU/ml (10-75) (P=0.105). Median EPO concentration was higher in DME patients than in patients with RVO or controls: DME, 430 mU/ml (41-3000) vs RVO, 76 mU/ml (30-806) (P<0.0001) vs controls, 25 mU/ml (10-75) (P<0.0001). CONCLUSIONS: EPO levels are not elevated in patients with macular oedema secondary to RVO. Patients with DME have high levels of EPO. These results suggest that EPO could be involved in the pathogenesis of diabetic retinopathy, but not in macular oedema secondary to RVO.

Increased plasma asymmetric dimethylarginine (ADMA) levels in retinal venous occlusive disease.

BACKGROUND: We investigated the levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA), as well as homocysteine and cysteine thiols, in a cohort of subjects affected by retinal vein occlusion (RVO) disease. METHODS: Capillary electrophoresis analysis was performed in both RVO subjects (n=54) and in a control group (n=32). RESULTS: No differences were found between controls and patients; however, after categorisation for RVO type, central RVO (CRVO) patients showed higher levels of ADMA (0.710+/-0.139 micromol/L) than controls (0.635+/-0.117 micromol/L) and branch RVO patients (0.642+/-0.096 micromol/L). Moreover, cysteine plasma levels were also significantly higher in CRVO patients than in controls (265.8+/-46.9 vs. 226.7+/-51.9 micromol/L, p<0.01), while homocysteine plasma concentration was more or less identical in all groups. CONCLUSIONS: We hypothesise that the elevated levels of cysteine in CRVO patients may post-translationally inhibit dimethylarginine dimethylaminohydrolase enzyme activity, as already described for homocysteine, thus contributing to the accumulation of ADMA in this patient group.

High-throughput capillary electrophoresis method for plasma cysteinylglycine measurement: evidences for a clinical application.

Increased levels in plasma homocysteine and cysteine, and more recently, decreased levels in cysteinylglycine have been indicated as a risk factor for vascular diseases. Most assays focused their attention only on homocysteine determination and when also other thiols were measured, analytical times drastically increased. By modifying our previous method for thiols detection, we set up a rapid capillary electrophoresis method for the selective quantification of plasma cysteinylglycine, cutting the analysis time of about 50%. Samples were treated with tri-n-butylphosphine as reducing agent, proteins were precipitated with trichloroacetic acid and released thiols were successively derivatized by the selective thiol laser-induced fluorescence-labeling agent 5-iodoacetamidofluorescein and separated by capillary electrophoresis. A baseline separation between peaks was obtained in about 2 min using 3 mmol/L sodium phosphate/2.5 mmol/L boric acid as electrolyte solution with 75 mmol/L N-methyl-D-glucamine at pH 11.25 in a 47 cm long capillary with a cartridge temperature of 45 degrees C. The method application was checked by measuring plasma Cys-Gly levels in a group of patients affected by retinal vein occlusion (RVO), an important cause of visual loss in the elderly. The low levels of Cys-Gly found in the RVO patients suggest that these small thiols may have importance in the disease development.

Endogenous erythroid colony formation in patients with retinal vein occlusion.

PURPOSE: The pathophysiology and causes of retinal vein occlusion (RVO) remain largely unknown. Latent forms of myeloproliferative disorders, which are diagnosed by the presence of in vitro endogenous erythroid colony (EEC) formation, are a well-known cause of intraabdominal vein thrombosis. The suspected diagnosis of a latent myeloproliferative disorder in a patient with RVO, based on the presence of EEC formation, led us to evaluate the association between latent myeloproliferative disorders and RVO. DESIGN: Observational case series in a national eye center. PARTICIPANTS: Forty-four patients, with a mean age of 46 years (range, 21-62) and central (n = 38) or peripheral (n = 6) RVO responsible for visual acuity decreased to 6/12 or less. METHODS: In vitro bone marrow culture. MAIN OUTCOME MEASURE: Endogenous erythroid colony formation in cytokine-free culture medium. Conventional diagnostic criteria for myeloproliferative disorders and the JAK2 V617F mutation (which is strongly associated with myeloproliferative disorders) were assessed in RVO patients showing EECs. RESULTS: Endogenous erythroid colony formation was observed in 12 of 44 (27%) patients with RVO, 13 of 35 (37%) patients with Budd-Chiari syndrome, and 52 of 53 (98%) patients with primary polycythemia (positive control groups) but not in 22 healthy bone marrow donors (negative controls) evaluated at the same time and by the same hematology laboratory. Neither conventional nor genetic diagnostic criteria for myeloproliferative disorders were observed in any patient with both RVO and an EEC at the time of diagnosis or during follow-up. CONCLUSIONS: Endogenous erythroid colony formation is frequently observed in patients with RVO independently of any detectable myeloproliferative disorder. This opens a new aspect of research on the pathophysiology of this sight-threatening disease.

Hyperhomocysteinemia and low methionine stress are risk factors for central retinal venous occlusion in an Indian population.

PURPOSE: The underlying cause of disturbed homocysteine metabolism is incompletely understood in young persons with central retinal vein occlusion (CRVO) with mild hyperhomocysteinemia (HHcys) and no other systemic disease in India. A 2-year prospective study was undertaken to determine whether HHcys is a risk factor for CRVO in an Indian population. METHOD: The prevalence of fasting HHcys was evaluated in a consecutive series of 29 patients with CRVO (mean age, 30 +/- 6 years) along with 57 age- and sex-matched control subjects (healthy subjects, mean age 27 +/- 5 years). Strict inclusion and exclusion criteria were used. Plasma levels of homocysteine (Hcys), methionine, cysteine, glutathione, B(12), and folate were measured. Multivariate logistic regression analysis was performed to determine the risk factors for CRVO. RESULT: Fifteen of 29 patients with CRVO (51.72%) exhibited HHcys (>15 muM). The mean Hcys level was significantly elevated in the patients with CRVO (19.1 +/- 13.1 muM) compared with that in the healthy control subjects (14.7 +/- 6.2 muM) with P = 0.04. The increased Hcys levels in CRVO cases was associated with decreased methionine (P = 0.052) and decreased B(12) (P = 0.001). A multivariate logistic regression analysis revealed an odds ratio of 1.9 (95% CI = 0.50-7.16) for Hcys and 15.9 for methionine (95%CI = 1.50-169.62; P = 0.022). CONCLUSION: Elevated Hcys and low methionine were risk factors for CRVO in an Indian population.

Plasma methionine determination by capillary electrophoresis-UV assay: application on patients affected by retinal venous occlusive disease.

Methionine is an important amino acid involved in protein synthesis and transmethylation reactions. It is also the precursor of homocysteine and cysteine, two important risk factors for cardiovascular diseases. As homocysteine research has gained impulsion, the evaluation of plasma methionine concentrations has acquired importance. Methionine measurement generally has been performed by HPLC after o-phthalaldehyde derivatization. Its separation from other amino acids is time-consuming. We set up a new specific capillary electrophoresis method in which analyte derivatization was avoided by sample concentration before analysis. Methionine was detected by UV absorbance at 204 nm with a detection limit of 0.5 micromol/L. By a capillary with an effective length of 50 cm filled with 125 mmol/L Tris phosphate buffer at pH 2.3, the separation occurred in less than 14 min. Precision tests indicated a good test repeatability for both migration times (coefficient of variation [CV]<0.3%) and areas (CV<2.0%). Moreover, a good reproducibility of intraassay and interassay tests was obtained (CV<2.9% and CV<3.5%, respectively). The Passing-Bablok regression and the Bland-Altman test for methods comparison suggest that the data obtained by our method and by a reference HPLC assay are similar. Assay performance was evaluated measuring methionine concentrations in retinal venous occlusive disease.