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Free radicals and cataracts

Free radicals and cataracts

Discussion Age-related cataracts are radiccals Nutritional supplements advice be multi-factorial in Free radicals and cataracts, with ROS Blackberry plant care oxidative damage considered radicls be a common factor catraacts[35][36]. Furthermore, treatment radica,s antioxidants did Nutritional supplements advice significantly affect catsracts body weights of Fre diabetic animals Figure 7 ; however, the rats treated with compound 4 appeared on average to eat slightly more during the course of the study and therefore weighed slightly more. Olmedilla B, Granado F, Blanco I, Vaquero M. In: Catala A ed Lipid peroxidation. Advanced search. Blood glucose levels at the start and end of the study were evaluated with a Nova Max blood glucose meter Nova Biomedical, Waltham, MA. Ophthalmic Res 30 1 —

Free radicals and cataracts -

One hundred and two non-diabetic subjects 50 with cataract and 52 non-cataract and diabetic subjects 56 with cataract and 50 non-cataract were recruited into the study. In the non-diabetic group, significantly low levels of catalase, GPX, and SOD activities were associated with cataract when compared with non-cataract.

No significant changes in catalase, GPX, and SOD activities were observed in the diabetic group between cataract and non-cataract. Senile cataract non-diabetic cataract was associated with significantly low levels of erythrocyte catalase, GPX, and SOD when compared with osmotic cataract diabetic cataract.

Our results indicate that erythrocyte antioxidant enzyme levels are decreased in senile cataract as opposed to osmotic cataract.

Assays of these erythrocyte enzyme activities could provide a marker to identify individuals predisposed to senile cataract. Cataract is one of the leading causes of blindness in the world today. Cataract occurs in diabetic subjects osmotic cataract as well as in non-diabetic subjects senile cataract ; in the latter group, age and radiation effects are the main predisposing factors.

Free radicals and reactive oxygen intermediates ROI have been implicated in a wide variety of degenerative diseases including cataractogenesis [ 3 ]. It is believed that oxidative stress and osmotic stress are involved in the pathogenesis of cataract [ 4 ]. Oxidative stress may result when the cellular antioxidant defense mechanisms are unable to keep pace with the detoxification of ROI.

These ROI mediate peroxidation of membrane lipids and cause extensive damage to proteins, leading to irreversible deleterious effects [ 5 ]. Osmotic stress may lead to the development of cataract in diabetic individuals. This is due to the accumulation of an osmotically active sugar, sorbitol, in the lens tissue [ 6 ].

Antioxidant enzymes that intercept and inactivate ROI are synthesized by all aerobic organisms [ 7 ]. Catalase, GPX, and SOD are important antioxidant enzymes that detoxify oxygen free radicals and hydrogen peroxide and thereby prevent oxidative damage.

The normal aging process is thought to occur mainly as a result of degeneration of enzymes that are involved in the antioxidant defense mechanism [ 8 ].

Reduced glutathione GSH plays a major role in the regulation of the redox status of the cell and protects tissues from lipid peroxidation [ 9 ]. Studies on the antioxidant status of the lens and blood in cataract patients have been extensively reported.

However, very few studies have been conducted on Sri Lankan patients with cataract. In developing countries, including Sri Lanka, India, and Kenya, cataract evolves earlier in life and is 3 times more prevalent than in developed countries [ 8 ].

The specific environmental and nutritional patterns of Sri Lankans may have a role in the oxidation process and in cataract formation.

The present study investigated the levels of erythrocyte catalase, GPX, and SOD activity with respect to cataract in a diabetic group and a non-diabetic group of Sri Lankans. Ethical clearance for the study was obtained from the Ethics Committee of the Faculty of Medicine, University of Kelaniya, Sri Lanka.

One hundred and two non-diabetic subjects and diabetic subjects in the age group 40—70 yr were recruited to the study from the Diabetic and Ophthalmological Clinics of the North Colombo Teaching Hospital, Sri Lanka.

Information was obtained regarding medical history and occupational background and informed consent was obtained from all subjects. A complete ophthalmological examination including slit lamp examination was done on all subjects by an ophthalmologist.

Of the non-diabetic subjects, 50 were diagnosed as cataract 21 females, 29 males, age 57 ± 9 yr and 52 as non-cataract 27 females, 25 males, age 52 ± 10 yr.

Of the diabetic group, 56 were diagnosed as cataract 24 females, 32 males, age 61 ± 9 yr and 50 as non-cataract 20 females, 30 males, age 54 ± 8 yr. Three ml of venous blood was obtained from every subject under aseptic conditions using disposable syringes and needles. Spectrophotometric assays of erythrocyte catalase, GPX, and SOD activities were performed within 3 hr of collection of the blood samples, using reagent kits manufactured by Randox Labs, Ltd.

For SOD assays, 0. Washed RBCs were mixed with 2 ml of cold distilled water and kept at 4°C for 15 min. The lysate was used to determine the SOD activity.

For erythrocyte GPX assays, 0. For erythrocyte catalase assays, 0. Then, 0. Data were expressed as mean ± SD; differences between enzyme activity levels in population groups were tested using the t-test, assuming equal variances in the two samples under comparison.

In the diabetic group, no significant changes were observed in catalase, GPX, and SOD activities between cataract and non-cataract subjects.

Comparisons between non-diabetic cataract senile cataract and diabetic cataract osmotic cataract groups indicated significant decreases in catalase, GPX, and SOD activities in the non-diabetic cataract group.

Erythrocyte catalase, GPX, and SOD activities of cataract and non-cataract subjects in non-diabetic and diabetic groups of Sri Lankans values are mean ± SD. The present study investigated 3 antioxidant enzymes, catalase, GPX, and SOD, with respect to cataract in diabetic and non-diabetic groups of Sri Lankans.

Oxidative stress has been implicated in cataractogenesis [ 4 ]. Direct estimation of blood oxidant levels is difficult because of the very short half life of free radicals; however, oxidative stress can be estimated indirectly by measuring levels of antioxidants in blood [ 11 ] or in erythrocytes [ 12 ].

The important antioxidant enzymes in the erythrocytes are catalase, GPX, and SOD [ 13 , 14 ]. Previous studies have reported that senile cataractous lenses are associated with decreased levels of SOD, GPX, and catalase [ 15 — 18 ].

Hence, the need to investigate the blood antioxidant enzyme levels of cataract patients. A definite relationship between blood antioxidant enzyme levels and the incidence of cataracts could provide a useful marker in the identification of subjects predisposed to cataracts.

Results of the present study demonstrate significant decreases in erythrocyte catalase, GPX, and SOD activities in patients with senile cataract non-diabetic cataract when compared with the controls non-diabetic non-cataract.

There is significant positive correlation between erythrocyte antioxidant enzymes in subjects with senile cataracts.

Our results confirm some previous findings that correlate with human cataract [ 19 , 20 ]. It is suggested that a decrease in the antioxidant status of the erythrocytes may increase the oxidative damage in tissues, including the oxidative modification of lens proteins observed in cataract.

However, in contrast to these data, increased blood levels of antioxidant enzymes have been reported to be associated with cataract [ 21 — 23 ]. This is thought to be a defensive response to increased levels of oxidation within the body.

There may be a synergistic effect between the intracellular anti-oxidant enzymes and extracellular and membrane bound antioxidants such as ascorbate, vitamin E, and beta-carotene; low levels of these vitamins and high levels of antioxidant enzymes could minimize oxidant damage [ 24 ].

Therefore it is appropriate to consider the total antioxidant status in the interpretation of these results. Among the diabetic subjects, no significant differences in erythrocyte catalase, GPX, and SOD activities were observed between the cataract and the non-cataract groups, indicating a non-significant role for these enzymes in the pathogenesis of diabetic cataract.

Further, it was observed in this study that diabetic cataract is associated with higher levels of catalase, GPX, and SOD activities than senile cataract.

These results are in agreement with a previous study, which showed that diabetic cataract is associated with higher levels of GSH reduced glutathione and lower levels of lipid peroxidation in the erythrocytes as opposed to senile cataract, indicating a non-significant role for GSH in the pathogenesis of diabetic cataract [Chandrasena LG.

The changes in oxidation reduction status of erythrocytes in the development of cataract in diabetic and non diabetic subjects. Presented at the Annual Meeting of the American Association for Clinical Chemistry, 25—29 July , Los Angeles, CA].

The influx of glucose into the diabetic lens, and its oxidation through the polyol pathway, leads to the accumulation of sorbitol in the lens, which generates an osmotic stress that may be a major contributory factor in the development of diabetic cataract [ 25 ].

Further, there is variation in the activities of antioxidant enzymes reported for diabetic cataract [ 25 , 26 ]. Antioxidant medications, systemic diseases, and long term complications of diabetes such as non-enzymatic glycation and autoxidation of glucose may have significant effects on the antioxidant status of diabetic subjects.

However, chronic oxidative stress generated by the polyol pathway is likely to be an important contributory factor in the slow and progressive development of diabetic cataract. In summary, erythrocyte antioxidant enzyme activity levels reflect the changes taking place in the development of senile cataract.

Assays of these enzyme activities could provide a marker for the early detection of senile cataract. This research was funded by the Natural Resources, Energy and Scientific Authority and the University of Kelaniya, Sri Lanka.

We thank Mr. Senarath and Mr. Keerthisena for technical assistance. Copyright © by the testng Association of Clinical Scientists.

User Name Password Sign In. Erythrocyte Antioxidant Enzymes in Patients with Cataract Lal G. Chandrasena 1 , Sureka Chackrewarthy 1 , P. Teckla M. Perera 1 and Daya de Silva 2 1 Department of Biochemistry and Clinical Chemistry, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka; 2 Eye Hospital, Colombo, Sri Lanka Address correspondence to Lal G.

Chandrasena, Ph. Box 6, Thalagolla Road, Ragama, Sri Lanka; tel 94 1 ; fax 94 1 ; e-mail: dgmnh{at}sltnet. Previous Section Next Section. View this table: In this window In a new window.

Table 1. Previous Section. Bunce GE, Kinoshita J, Horwitz J. Nutritional factors in cataract. Annu Rev Nutr ; 10 : — CrossRef Medline Google Scholar.

Taylor A, Nowell T. Oxidative stress and antioxidant function in relation to risk for cataract. Adv Pharmacol ; 35 : — There is moderate evidence for an association with sunlight and cataract but weak evidence for sunlight and AMD.

The few studies that have investigated this suggest an adverse effect of biomass fuels on cataract risk. The antioxidant defence system of the lens and retina include antioxidant vitamins C and E and the carotenoids lutein and zinc, and there is mixed evidence on their associations with cataract and AMD from epidemiological studies.

Most epidemiological studies have been conducted in well-nourished western populations but evidence is now emerging from other populations with different dietary patterns and antioxidant levels.

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Advanced Search. Skip Nav Destination Close navigation menu Article navigation. Volume 44, Issue 3. Topic Editor s. Tsubota K. Google Scholar. Article Navigation.

Review Articles September 09 Free Radicals, Antioxidants and Eye Diseases: Evidence from Epidemiological Studies on Cataract and Age-Related Macular Degeneration Subject Area: Ophthalmology.

Fletcher A. Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK. This Site. Ophthalmic Res 44 3 : — Article history Received:.

Cite Icon Cite. toolbar search Search Dropdown Menu. toolbar search search input Search input auto suggest. Abstract Cataract and age-related macular degeneration AMD are the major causes of vision impairment and blindness worldwide.

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Thank Free radicals and cataracts for visiting nature. You catqracts using a browser version with limited support for CSS. To obtain the radjcals experience, we recommend you use Fgee more up to ane browser or turn off Enhance energy and productivity mode raeicals Internet Explorer. In the meantime, Bloating prevention methods ensure continued support, Fat burn HIIT are Nutritional supplements advice the site without styles and JavaScript. Oxidative stress and antioxidant status were determined in forty healthy men and postmenopausal women aged 50—70 years F25, M15who underwent concurrent eye examinations. Blood samples were collected for analysing major well-known antioxidants by HPLC systems with UV and ECD detectors, total antioxidant performance using a fluorometry, lipid peroxidation determined by malondialdehyde using a HPLC system with a fluorescent detector and by total hydroxyoctadecadienoic acid HODE and F2-isoprotanes 8-iso-PGF 2 α using GC-MS. Twenty-seven F17, M10 of the 40 subjects were diagnosed to have early cataracts at the onset of the study, which were regarded as age appropriate lens opacities. Free radicals and cataracts


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