Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Amounts of reduced, oxidized, and protein-bound glutathione (GSH) were measured in normal and cataractous lenses of pups and adult dogs. Lenses from pups included normal lenses from clinically normal pups, clear lenses from Beagle pups bred for glaucoma, and congenital cataractous lenses from Miniature Schnauzer pups. Lenses from adults included normal lenses from normal mixed-breed dogs, congenital cataractous lenses from Miniature Schnauzers, and complete mature cataractous lenses from clinical patients of different breeds. Glutathione in the normal lenses from pups and adult dogs is predominantly reduced GSH; oxidized GSH is about 2.1% to 2.6% of the reduced GSH values. The reduced GSH values are lower in normal pups [7.08 mumoles/g (wet wt) of lens] than in adults [7.83 mumoles/g (wet wt) of lens]; reduced GSH values decrease further in cataract formation. The decrease in oxidized GSH values parallel those of reduced GSH, except in the advanced cataracts of clinical patients in which oxidized GSH [0.045 mumoles/g (wet wt) of lens] was 9% of the GSH values. The GSH bound to soluble and insoluble lens proteins of congenital cataractous Miniature Schnauzer pups was significantly (P less than 0.01 and P less than 0.02, respectively) lower per gram of protein than that in pups with normal lenses. However, the soluble and insoluble protein-bound GSH of congenital cataractous lenses of adult Miniature Schnauzers and lenses in clinical patients with mature cataracts [based on mumole of GSH/g (wet wt) of lens] were not significantly different (P greater than 0.05) from that in adult dogs with normal lenses.
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PMID:Reduced, oxidized, and protein-bound glutathione concentrations in normal and cataractous lenses in the dog. 710 4

The direct effect of 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] on rat crystalline lens was investigated in this study. 12(S)-HETE lowered the glutathione (GSH) level and GSH reductase activity in the lens, while accelerating aggregation and insolubilization of lens proteins and production of thiobarbituric acid-reactive substances. The study also indicated that 12(S)-HETE insolubilized alpha-crystalline and induced opacification of the lens when the lens was incubated with 12(S)-HETE. From the results, we presumed that 12(S)-HETE may be oxidized or peroxidized easily and automatically in the air. The substances derived from 12(S)-HETE by oxidation or peroxidation may give the action disordering lens normalcy and induced cataract formation. Thus, the direct effect of 12(S)-HETE may of no benefit to the crystalline lens.
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PMID:Direct effect of 12(S)-hydroxyeicosatetraenoic acid on rat crystalline lens is perturbation of lens normalcy. 749 88

Single viable fiber cells have been isolated from the cortex of rat ocular lens by proteolytic digestion of the intact lens in calcium-free media. In isomolar sucrose, the isolated cells maintain their fiber-shaped morphology and exclude trypan blue. The surface morphology of the isolated fiber cells appears to be largely unaffected by the isolation procedure. The concentrations of adenine nucleotides, GSH, GSSG and the rate of glycolysis in the isolated fiber cells were comparable to those in the cortex. Upon perfusion of the tissue chamber with Ringer's solution, the fiber cells undergo a series of transformations, beginning with cell swelling, periodic blebbing along the longitudinal cellular axis, and eventual disintegration of the fiber into a number of resealed globules or round cells which resemble light-scattering areas in human cortical and supranuclear cataract. This disintegrative globulization of the fiber cells appears to be mediated by calcium influx, as it was prevented or delayed by a reduction in extracellular calcium concentration, verapamil or lanthanum. Since disturbances in calcium homeostasis are associated with various forms of cataract, such Ca(2+)-mediated disintegrative globulization of the fiber cells may be responsible for the formation of light scattering centers during cataractogenesis.
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PMID:Calcium-mediated disintegrative globulization of isolated ocular lens fibers mimics cataractogenesis. 755 94

There are two approaches to the question of whether solar radiation contributes to human cataract. The first, epidemiological studies, investigates correlations between man's environmental UV dose and cataract frequency. The second, animal models, investigates the effects of varying UV strengths and spectra on lens opacification in vivo or in vitro. While the latter approach typically provides for direct evidence, the data must still be extrapolated to human lenses. Results of physiological studies suggest that UV photons interact with proteins of the epithelial cell membranes, in particular tryptophan residues, transport ATPases and cytoskeletal proteins. One hypothesis is that damage to ion pumps and channels accumulates over the years as repair processes incompletely restore membrane function. Peroxidative damage is likely in view of the formation of UV-induced lipid peroxides in the lens epithelial membranes. Loss of homeostatic control of ions, particularly Ca++, leads to crystallin disorder in small regions of the underlying fiber cells. In our diabetic cataract studies, intracellular Ca++ electrodes detected large shifts in intracellular Ca++ before bulk-lens changes were apparent. Similar occurrences likely characterize UV cataract. Our lab is one of few studying lens physiology and how it is altered following transient exposures to UV-B and UV-A, both of which pass through the cornea. Some changes include: loss of epithelial cell GSH; elevated Ca++; loss of membrane voltage; impaired transport of Na+; increased permeability to ions and water; inhibition of critical enzymes; and a decrease in the rate of membrane synthesis.
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PMID:A review of the evidence that ultraviolet irradiation is a risk factor in cataractogenesis. 763 90

Ultraviolet light is a non-ionizing radiation that induces photochemical reactions in the tissue. Its spectral A and B ranges are partially absorbed by the cornea and/or lens thus causing damage on the cellular, cell physiological and molecular level. UV-A does not seem to damage the cornea permanently and its effects in the lens have a very prolonged latency period. Typical reactions of the cornea are oedema, punctuate keratitis (photoelectric keratitis) and neovascularization. In the lens all reactions that could be evidenced, were located in the epithelium and in the outer cortical fiber cells. In vivo UV-A induces swelling and slight vacuolation of the anterior suture system, but apart from these transient effects, only very limited permanent damage could be demonstrated. UV-B induces the formation of an anterior subcapsular cataract, starting also with vacuolation of the suture system. These morphological characteristics can be visualized at the slitlamp microscope. Histologically, sutural irregularities (UV-A) and epithelial hyperplasia with capsular multiplication (UV-B) as well as disintegration of the anterior suture system could be observed. Patho-physiologically, a reduction of lens fresh weight (UV-B) as well as changes of the equilibrium of reduced and oxidized glutathione (GSH/GSSG) could be demonstrated. On the protein-biochemical level, changes in the ratio of water-soluble versus water-insoluble protein could be evidenced, as well as effects on specific crystallin fractions, namely alpha-crystallin. In addition, the appearance of a newly synthetized 31 kDa protein could be demonstrated in UV-B irradiated mice.
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PMID:In vivo studies on the effect of UV-radiation on the eye lens in animals. 763 91

The enhancement of UVB on the surface of the earth due to stratospheric ozone depletion may increase the risk of photochemically induced cataract. In this study, changes in the content of certain biological parameters were used as a marker to study ocular toxicity. A significant enhancement in the level of H2O2, LP and Pi, along with the depletion of GSH (antioxidant-defence system) in serum, aqueous humor and lens of albino mice exposed to UVB was observed. The level of Ca++ increased in serum and aqueous humor but decreased considerably in the lens due to increase in UVB exposure. These observations provide further clues to support the involvement of oxidative stress and Ca++ in the events leading to the formation of cataract.
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PMID:Ultraviolet-B effects on ocular tissues. 775 17

Nuclear cataract, a major cause of loss of lens transparency in the aging human, has long been thought to be associated with oxidative damage, particularly at the site of the nuclear plasma membrane. However, few animal models have been available to study the mechanism of the opacity. Hyperbaric oxygen (HBO) has been shown to produce increased nuclear light scattering (NLS) and nuclear cataract in lenses of mice and human patients. In the present study, older guinea pigs (Initially 17-18 months of age) were treated with 2.5 atmospheres of 100% O2 for 2-2.5-hr periods, three times per week, for up to 100 times. Examination by slit-lamp biomicroscopy showed that exposure to HBO led to increased NLS in the lenses of the animals after as few as 19 treatments, compared to lenses of age-matched untreated and hyperbaric air-treated controls. The degree of NLS and enlargement of the lens nucleus continued to increase until 65 O2-treatments, and then remained constant until the end of the study. Exposure to O2 for 2.5 instead of 2 hr accelerated the increase in NLS; however, distinct nuclear cataract was not observed in the animals during the period of investigation. A number of morphological changes in the experimental lens nuclei, as analysed by transmission electron microscopy, were similar to those recently reported for human immature nuclear cataracts (Costello, Oliver and Cobo, 1992). O2-induced damage to membranes probably acted as scattering centers and caused the observed increased NLS. A general state of oxidative stress existed in the lens nucleus of the O2-treated animals, prior to the first appearance of increased NLS, as evidenced by increased levels of protein-thiol mixed disulfides and protein disulfide. The levels of mixed disulfides in the experimental nucleus were remarkably high, nearly equal to the normal level of nuclear GSH. The level of GSH in the normal guinea pig lens decreased with age in the nucleus but not in the cortex; at 30 months of age the nuclear level of GSH was only 4% of the cortical value. HBO-induced changes in the lens nucleus included loss of soluble protein, increase in urea-insoluble protein and slight decreases in levels of GSH and ascorbate; however, there was no accumulation of oxidized glutathione. Intermolecular protein disulfide in the experimental nucleus consisted mainly of gamma-crystallin, but crosslinked alpha-, beta- and zeta-crystallins were also present.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Nuclear light scattering, disulfide formation and membrane damage in lenses of older guinea pigs treated with hyperbaric oxygen. 778 3

Glutathione peroxidase activity (GSH-PX) and malondialdehyde (MDA) level of experimental traumatic cataract in rabbit were determined at various intervals after needling. GSH-PX activities decreased in the lens after perforated trauma from 8 hours to 21 days, meanwhile the MDA level increased markedly. The results demonstrate that free radicals are involved in the formation of traumatic cataract.
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PMID:[The dynamic changes in glutathione peroxidase activity and malondialdehyde level in experimental traumatic cataract in rabbit]. 780 45

We evaluated the inhibitory effect of melatonin, a recently discovered scavenger of free radicals, on cataract formation in the newborn rat. The glutathione synthesis inhibitor, buthionine sulfoximine (BSO) (3 mmol/kg), was intraperitoneally injected into newborn rats for 3 consecutive days starting on day 2 after birth. These glutathione depleted rats develop cataracts. Melatonin (4 mg/kg) was injected intraperitoneally into half of the rats once a day beginning at day 2 after birth; the other half of the animals received solvent daily. The incidence of cataract was observed on day 16, after the eyes of the newborn animals had opened. Both reduced glutathione (GSH) and oxidized glutathione (GSSG) levels were measured. Cataracts were observed in all animals (18/18) treated with BSO plus solvent. The incidence of the cataract in the animals cotreated with melatonin was only 6.2% (1/15). Total lenticular glutathione (GSH + GSSG) levels in BSO only treated rats were reduced by 97%. The total glutathione in the lens of the BSO plus melatonin group was significantly higher (by 3%) than that of the BSO only group. The percentage of the total glutathione as GSSG for the BSO plus solvent group was higher than the control value. Cotreatment of BSO injected rats with melatonin (4 mg/kg/day) clearly reduced cataract formation proving that it is directly or indirectly protective against oxidative stress which accompanies glutathione deficiency. The inhibitory effects of melatonin on cataract formation in this study could be due to melatonin's free radical scavenging activity or due to its stimulatory effect on glutathione production.
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PMID:Inhibitory effect of melatonin on cataract formation in newborn rats: evidence for an antioxidative role for melatonin. 786 32

The activities of glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), superoxide dismutase (SOD) and the contents of malondialdehyde (MDA) and free radicals were measured, and the morphological changes were observed in the lens of control rats, selenium-deficient (SeD) and/or vitamin E deficient (VED) rats. The activities of GSH-Px in the lens of SeD rats decreased significantly. The GSH-Px activities of lens were positively related to erythrocytes selenium level. There was a free radical at g = 2.0015 in the rat lens of all groups, but the content of free radicals in the lens of SeD group was significantly higher than that of the control group. The free radical content of lens was negatively related to erythrocytes selenium level, as well as the GSH-Px activities in the lens. In vitro, ultraviolet radiation caused the generation of another kind of free radical (g = 2.0097) in the lens of all groups, but the amount of the free radical in the lens of the SeD group was also significantly higher than that of the control group. The activities of SOD and GSSG-R in VED rat lens were significantly decreased. The amount of MDA in the lens of SeD and/or VED rats were significantly increased. The results showed that the decrease of antioxidative capability in the lenses of SeD and/or VED rats accelerated the lipid peroxidation and generation of free radicals. Although only early morphological changes in SeD and/or VED rat lens were observed, it is considered that selenium and vitamin E deficiency may be involved in the occurrence of cataract.
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PMID:Biochemical and morphological changes in the lenses of selenium and/or vitamin E deficient rats. 794 5


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