Xanthine oxidase activity in patients with age-related cataract associated with hypertension

Reactive oxygen species and lipid peroxidation are important factors that contribute to the development of age-related cataract. The study included 130 patients with age-related cataract, 69 of whom were diagnosed with hypertension (HT), 20 with hypertension and type 2 diabetes mellitus (DM), and 41 had no accompanying condition. The following parameters were measured in the serum of the examinees: products of lipid peroxidation malondialdehyde (MDA) and lipofuscin-like fluorophores (LLF), activity of prooxidative enzymes xanthine oxidase (XO) and myeloperoxidase (MPO), antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), the concentration of thiol groups, and the ferric reducing activity of plasma. The activity of prooxidative enzymes XO and MPO was higher in the plasma of patients with HT (XO=9.0±1.2 U/L; MPO=77.3±8.4 U/L) and with HT and DM (XO=11.9±0.9 U/L; MPO=89.5±5.0 U/L) compared to patients with age-related cataract (XO=6.2±0.9 U/L; MPO=52.4±6.3 U/L; P<0.01). Our research has shown that patients with age-related cataract and hypertension were exposed to increased oxidative damage of biomolecules, based on the increased plasma LLF and MDA content and decreased levels of thiol groups. Oxidative changes of biomolecules in these patients were associated with increased activity of the XO, MPO, and GPx enzymes and a lower extracellular SOD activity and total ferric reductive ability of plasma.

Role of anti-oxidant enzymes superoxide dismutase and catalase in the development of cataract : study of serum levels in patients with senile and diabetic cataracts.

Cataract is a universal phenomenon in old age and the most common cause of blindness worldover. Oxidative stress is believed to be a key factor in the gradual loss of transparency of lens. Free radicals formed result in derangement and opacification of lens fibres. Superoxide dismutase, catalase and glutathione peroxidase are major anti-oxidant enzymes, which protect against free radicals. The purpose of this study is to evaluate the role of anti-oxidant enzymes - superoxide dismutase and catalase in the development of cataract in senile and diabetic persons. Serum levels of major anti-oxidant enzymes-superoxide dismutase and catalase were estimated in 20 patients with diabetic cataract, and matched with another 20 patients of senile cataract taken as control. Estimation of superoxide dismutase was done by improved spectrophotometric assay based on epinephrine auto-oxidation at 480nm, while catalase estimation was done by the method of Hugo Aebi. The mean serum levels of superoxide dismutase and catalase were lower as age increased. These enzymes were also significantly lower in diabetic cataracts (9.13 and 16.42 units/ml) as compared to senile cataracts (25.30 and 57.27units/ml). Oxidative stress is one of the major factors contributing to cataract formation. In diabetics where there is increased oxidative stress, the serum levels of the major anti-oxidant enzymes decrease, which lead to early cataract formation. It may be concluded that oxidative stress is an important factor in the development of diabetic cataracts and anti-oxidants may have a role in decreasing the incidence of cataract.

Antioxidant enzymes and peroxidation in galactogenic cataract.

The antioxidant enzymes like catalase and superoxide dismutase (SOD) were studied in erythrocytes and lens at various stages of cataractogenesis in albino rats. The rate of peroxidation was measured by assessing the malondiadehyde (MDA) in lens and plasma. The insoluble and soluble protein fractions were measured in lens to study the protein crosslinkings in relation to the above said parameters. Cataract was induced in albino rats by feeding it with 30% galactose as part of the normal diet (w/w) for 30 days. The results show a decrease of SOD and catalase with concomitant increase of MDA and insoluble protein with the advancement of cataract.

Influence of UV-irradiation on enzymes in mouse ocular lens: in vitro studies.

PURPOSE: In vitro study of the enzymes involved in aerobic, anaerobic and hexose monophosphate shunt in ultraviolet radiation exposed mice lenses. METHOD: Of the selected enzymes, lactic dehydrogenase (LDH) was representative of anaerobic glucose oxidation, succinic dehydrogenase (SDH) of the aerobic oxidation, and Glucose-6-phosphate dehydrogenase (G-6-PDH) of the Hexose Monophosphate (HMP) shunt. Other enzymes studied were ATPase and glutathione reductase (GR). RESULTS: Experiments with mice lenses in vitro showed that transparent lens became opaque following UV-irradiation at 360 nm. Opacification of the lens was accompanied by a change in enzyme activities for energy metabolism. CONCLUSION: These changes were progressive in a manner analogous to sequential morphological changes, which would be crucial in maintaining lens transparency.

El mapa enzimático en la catarata senil humana / Enzymatic map in the human senile cataracts

Se ha señalado que las cataratas seniles están asociadas con cambios muy marcados en la actividad enzimática del cristalino. Por esta razón, en el presente estudio se determinó la actividad de las siguientes enzimas: aldolasa (ALD), isocítrico dehidrogenasa (ICD), colinesterasa (CHE), leucín aminopeptidasa (LAP), 5ïNucleotidasa (5ï-N) y ceruloplasmina (Cp) en cataratas seniles y en cristalinos sanos. La actividad enzimática en el cristalino normal es similar a la que se detecta en las diferentes especies. En las cataratas seniles se encontró una disminución (p<0,05) en la actividad de ALD, ICD, LAP y 5ï-N, sin cambio en la CHE y en la Cp. La disminución en las enzimas glucolíticas (aldolasa e isocítrico dehidrogenasa) determinan un "bloqueo parcial" de la glicólisis necesaria para producir la energía y mantener la transparencia del cristalino. La reducción en la actividad de la LAP favorece la acumulación, la agregación y la precipitación de las proteínas y de los péptidos que se produce en los cristalinos envejecidos. Estos agregados se consideran importantes en el desarrollo de la catarata. La pérdida de Zn elevado a la 2+ en las cataratas seniles explica en parte la disminución de la 5ï-N y de la LAP. Se discuten estos resultados y se concluye que los cambios enzimáticos alteran el metabolismo normal del cristalino y causan la catarata senil. Es de interés señalar que la 5ï-N y la ceruloplasmina es la primera vez que se miden en el cristalino tanto normal como cataratoso. La Cp representa un mecanismo de protección contra los radicales libres que se generan por efecto de la luz sobre el cristalino y otros tejidos oculares y será objeto de estudios ulteriores

Synergetic effects of U-V radiations and malnutrition of lens (experimental study).

The synergistic effects of protein deficiency and U-V radiation is cataractogenic as seen in our experimental model though individually these had no damaging effect on enzymatic profile and clinical appearance.

Glutathione and glutathione-related enzymes in busulfan treated rat lens.

Glutathione (GSH) and GSH-related enzymes, glutathione reductase (GR), gamma-glutamyl cysteine synthetase (gamma-GCS), gamma-glutamyl transpeptidase (gamma-GTP), glutathione S-transferase (GST) and adenosine triphosphatase (ATPase) enzymes were analysed to study the effect of busulfan on the defence mechanisms of the lens. All these enzymes were found to increase significantly except GSH which showed only 7.9% increase as compared to controls in precataractous stage. These results affirm that busulfan is capable of evoking a response from the enzymes involved in the various pathways of GSH enabling the lens to prolong its clarity. The cataractous lenses showed significant decrease in all these parameters. Here, the impairment of the defense mechanism (GST, GR) and the total ATPase may be attributed to the cumulative action of the drug which can react with -SH groups of these enzymes, ultimately causing opacification.

Lactate dehydrogenase and phosphoglucose isomerase in patients with retinoblastoma and congenital cataract

Os autores determinaram a atividade enzimática da desidrogenase láctica (LDH) e da fosfoglicose isomerase (PGI) no humor aquoso (HA) e soro (S) de pacientes com catarata congênita. Encontraram uma diferença estatiscamente significativa entre as médias da desidrogenase láctica no humor aquoso (LDHha), da fosfoglicose isomerase no humor aquoso (PGIha) e da desidrogenase láctica no soro (LDHs) nos dois grupos de pacientes. Dos portadores de retinoblastoma, 75.0%, 70.0%, 10.8% e 8.1% apresentaram aumento de LDHha, PGIha, LDHs e PGIs, respectivamente, quando comparados com os portadores de catarata congênita. No grupo de portadores de catarata congênita, näo houve correlaçäo ente as enzimas no humor aquoso e/ou soro. No grupo de portadores de retinoblastoma, houve uma correlaçäo positiva entre as duas enzimas no humor aquoso e entre as duas enzimas no soro. O padräo isoenzimático da LDH no humor aquoso dos portadores de retinoblatoma apresentou, como fraçöes mais elevadas, as isoenzimas LDH4 e LDH3. Do ponto de vista enzimático, o valor absoluto da LDH e da PGI no humor aquoso constitui o melhor critério para o diagnóstico de retinoblastoma. Resultados falso-negativos foram observados em 25% das dosagens da LDHha e em 30% das dosagens da PGIha

Actividad de diversas enzimas relacionadas con el metabolismo glúcido en cataratas seniles / The activity of various enzymes related with the metabolism carbohydrates in senile cataracts

En la presente investigación se desarrolló un estudio clínico, del tipo "caso-control", sin hipótesis previa, observándose la distribución de las alteraciones de ciertas enzimas vinculadas al metabolismo intermediario de los glúcidos, como son: la glucógeno fosforilasa, la glucosa-6-fosfatasa, la amilasa, la deshidrogenasa láctica y la fosfohexosaisomerasa en cristalinos con cataratas seniles en comparación con lo que se detecta en cristalinos humanos normales, no opacificados. Las actividades enzimáticas de los cristalinos normales fueron muy parecidas a las detectadas en diferentes especies animales, con excepción de la actividad amilolítica. En las cataratas seniles, los resultados obtenidos muestran una marcada disminución en todas las actividades enzimáticas valoradas. Se establecieron las correlaciones correspondientes y se concluye que los hallazgos obtenidos pudieran deberse a una disminución en la estabilidad y/o en la actividad de estas enzimas, por diversos factores, lo cual produce un grave deterioro del metabolismo glucídico en las cataratas seniles, con interferencia en los mecanismos de producción de energía. Los resultados confirman lo establecido previamente en diversas especies, con respecto a la edad y al cristalino