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Kovaceva et al., (1997) reported the mammalian corneal epithelial antioxidants like glutathione peroxidase, superoxide dismutase and prooxidant such as xanthine oxidase having different types of activities. The enzyme activities of antioxidant superoxidase dismutase and glutatione peroxidase as well as proxident xanthine oxido reductase /xanthine oxidase were studied using biochemical methods. End results prove that superoxide dismutase activity is high in rabbits and guinea pigs where as in pigs the activity is low and in cow it is nearly absent. In contrast, glutathione peroxidase activity is high in cows, pigs and rabbits, where as in guniea pig that activity is low. The findings for proxidant enzymes level reveal elevated xanthine oxidoredutase /xanthine oxidase activities in rabbits, lower activities in guinea pigs, very low activity in cows and no activity in pigs. In conclusion the results demonstrate inter species variations in activities of enzymes participating in antioxidant/ pro-oxidant balance in the corneal epithelium. It is suggested that the levels of anti oxidant and pro-oxidant enzymes studies in the corneal epithelium might be associated with the diurnal or nocturnal activity of animals.
Gupta et al., (1997) reported that topical aspirin provides protection against galactose induced cataract. Effect of two times daily administration of aspirin eye drops on the onset and development of cataract-induced by 30% galactose diet was examined. After one month of galactose administration, whereas all control group rats showed entire state IV opacity, those receiving aspirin eye drops proved just mild cataractous alter stage I. Addition of aspirin in the medium considerably maintain glutathione levels and reduced dulcitol formation. Intraocular diffusion studies using isolated goat cornea should excellent penetration by salicylate indicating feasiblity of topical administration. The final results of the current study express that topical aspirin contain significant anticataract activity in galactosemic cataract.
Vani and Rawal et al., (1996) studied the effect of riboflavin supplementation on glutathione and glutathtione redox cycle in selenite-induced cataractous lenses. The riboflavin supplemented into the control grouprats and the lens were isolated and determine the biological parameters such as level of proteins, decreased glutathione (GSH) and the activity of y-glutamylcysteine synthetase (y-GCS), glutathione peroxidase (Gpx) and glutathione reductase (GSSH). The cataractous rats are supplemented with riboflavin showed high levels of enzyme activity and metabolites as compared to the negative control rats. The end results of this study indicate to the role of riboflavin in the prevention of cataract formation, induced by selenite.
Micelli-Ferrari et al., (1996) evaluated the effect of lipid peroxidation in the main cause of myopic and senile cataract. The study was carried out on 34 lenses (nucleus and epinucleus) (9 normal lenses, 14 idiopathic senile cataract lenses and 11 severe myopic cataract lenses) and vitreous of 19 (7 non-myopic, 7 myopic, and 5 control) subjects. Glutathione and malondialdehyde was assayed. Cataractous lenses showed a decreased amout of GSH and increased concentration of GSSH compared with normal lenses. A higher oxidative utilization of GSH was determined in myopic cataracts compared with senile ones. Also, increased levels of malondialdehyde were examined both in cataractous lenses and in the vitreous of myopic patients compared with control and the senile ones. The observed changes strongly said that retinal lipid peroxidation might play a importent role in human cataractogenesis, particularly in the myopic type.
Tao et al., (1991a) reported the effect of aldose reductase inhibitors on naphthalene induced cataract development in rats. Brown Norway rats were given naphthalene by gavage at a dose of 0.7 g/kg were fed normal rat chow containing aldose reductase inhibitors sorbinil, FK 366, A 11576 and 0.05% Tolrestat and Ponalrestat to prevent the glucose induced cataractogenesis the lens histological changes in these rats were observed over a 3 months period by portable slit ââ‚¬"lamp microscopy. The compound A11576 showed a dose-dependent reduction in naphthalane-induced cataract formation, with no naphthalene-assosiated aggregation observed in toluidine blue-coloured lens segment. Sorbinil also decreaseded lens histological changes but ponalrestat, tolrestat and FK366 had no significant effect. These results suggest that structurally different aldose reductase inhibitors are prevent the naphthalene-induced cataract formation in lens but it is not related to the inhibition of aldose reductase enzyme.
Tao et al., (1991b) compared the effect of two types of aldose reductase inhibitors on several biochemical parameters in naphthalene-induced cataract of the rat over a time span of 102 days of treatment. Feeding of naphthalene daily to brown Norway rats resulted in gradual, progressive development of zonular opacities. As compared to control animals, the values of soluble protein, soluble glutathione, glutathione peroxidase, glutathione reductase were decreased in rats fed either naphthalene or naphthalene +FK366, a carboxylic-acid-type aldose reductase inhibitor. In marked contrast, treatment with A11576, a hydantoin-type aldose reductase inhibitor, maintained the values of most parameters at levels that were similar to those of the controls, and all lens remained clear. A decline of glutathione was noted in all naphthalene-fed rats, irrespective of whether these animals ha d been treated with aldose reductase inhibitor. The great decrease of glutathione with A11576 suggests that this inhibitor acts at some step in naphthalene metabolism following formation of naphthalene epoxide.
Truscorr et al., (1990) When intact rat lenses were incubated in artificial aqueous humor in the presence of 1 mM calcium and a sulfhydryl reagent p-chloromercuriphenyl sulfonate (pCMPS) a visible annular opacity developed within 4 hours. Gel electrophoresis of the soluble and urea-soluble fractions from lenses exposed to 1 mM calcium for periods of up to 14 hours showed no evidence for crystalline degradation and only minor proteolysis of cytoskeletal proteins. When lenses were incubated under identical conditions, but with 5 mM calcium, the degree of opacification increased up to approximately 8 hours and then remained constant. A progressive loss in cytoskeletal proteins was observed which correlated with a further increase in free calcium such that by 14 hours of incubation, when the internal calcium approached 1mM, most of the spectrin and vimentin present in the cortex of the lens had disappeared. An unidentified 110-kilodalton protein also disappeared from lenses incubated in 5 mM calcium. These results indicate that proteolysis by calcium-dependent enzymes such as calpain may play a significant role in cytoskeletal regulation and metabolism in the lens.
Datiles et al., (1982) studied the effect of sorbinil, an aldose reductase inhibitor on cataract induced by galactose using a light microscopic study. Cataract formation in galactosemic rats was studied by ophthalmoscopy, slit-lamp bio microscopy and by light microscopy using plastic embedding with methacrylate. Untreated rats developed nuclear cataract by 14 days and mature cataracts by 21 days However, rats treated with the aldose reductase inhibitor sorbinil did not develop any cataractous change for up to 8 months of 50% galactose feeding and could not be distinguished from normal controls. This strongly suggests that aldose reductase is the common factor involved in the formation of sugar cataracts.
Hightower et al.,(1982) Cataracts in isolated rabbit lenses were produced by elevation of inter cellular calcium. Experimental methods were successful in increasing levels of total and bound calcium molecule, often without significant alteration in potassium, sodium or water content. Although the more amount of calcium was predominantly accumulate with water-soluble proteins and was easily diffusible, a significant amount was bound to membranes and cytosol water-insoluble proteins. Thus, in lenses with a 10-times increase in total calcium, the bound calcium increased two times, almost 35% of which remained and fixed to water-insoluble protein and membrane protein after exhaustive (72 hr) dialysis. In contrast, above 95% of the calcium in water-soluble protein fractions was separated by dialysis.
Niyogi SK ,Rediers et al.,(1969)Studies were made to isolate and characterize the active principle of Abrusprecatorius. The toxic principles do not appear to be extractable by petroleum ether, isopropyl alcohol or absolute ethanol, but are extractable by water. Mice are able to develop tolerance to the toxic principles. In addition to the toxic principles, Abrus may also contain an inhibitor of the toxin.
Heyningen and Pirie et al.,(1967) investigated the metabolism of naphthalene and its toxic effect on the eye. Rabbits were fed with 1g/kg of napthalene orally. Dissection of eye tissues revealed browning of the lens and eye humours, blue fluorescence of the eye humours and crystals in the retina and vitreous body. There was also a decrease in the humours. The metabolites of naphthalene finally are converted 1, 2 ââ‚¬"naphthaquinone and hydrogen peroxide which accounts for the disappearance of ascorbate, appearance of crystals of calcium oxalate in the eye and the brown colour of lens.