UMLS:C0086543 - FACTA Search

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Query: UMLS:C0086543 (cataract)
29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Age-related changes in glutathione (GSH) content of eye lenses were investigated in senescence-accelerated mouse (SAM) and C57BL/J mice. 2. The decrease of GSH content with aging is markedly observed in SAM strains. 3. The oxidized glutathione (GSSG) content of eyes increased significantly with aging in SAM. 4. Ophthalmic changes, including cataract, increased with age in SAM alone. 5. The decrease of GSH content and the increase of GSH oxidation may be involved in the pathogenesis of cataract in SAM.
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PMID:Age-related changes in GSH content of eyes in mice--a comparison of senescence-accelerated mouse (SAM) and C57BL/J mice. 135 33

This paper presents an overview of the current state of our knowledge concerning the metabolism and function of glutathione (GSH) in the lens, with particular reference to the contributions of Dr Jin H. Kinoshita to this field. Glutathione in the lens is synthesized from its constituent amino acids and degraded by mechanisms involving transpeptidation and hydrolysis. The turnover of GSH in the lens is due to its catabolism rather than transport of GSSG as is the case in red blood cells and some other tissues. Three aspects of the functional role of GSH in cataract formation are considered. First, GSH may be important in maintaining protein thiols in the reduced state, thus preventing the formation of high molecular weight protein aggregates which are the basis for light scattering and lens opacification. A second function may be to protect membrane -SH groups that are important in cation transport and permeability. A third functional role is to detoxify hydrogen peroxide and other organoperoxides. The glutathione redox cycle is intimately involved in the detoxification of H2O2 which is normally present in the aqueous humor.
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PMID:Glutathione and its function in the lens--an overview. 219 12

In this study we have investigated the oxidative metabolism of red cells (RBC), plasma, serum and aqueous humour of healthy subjects and of age-matched cataractous patients with and without chronic renal failure (CRF). Reduced glutathione (GSH) levels in RBC were lower in CRF patients than in the other groups. Oxidized glutathione (GSSG) plasma levels in CRF patients were higher than those of controls and cataractous subjects. The activity of the enzyme glucose-6-phosphate dehydrogenase in RBC was significantly reduced in CRF patients with respect to the other two groups. The levels of malondialdehyde (MDA) in RBC and in lens were about twice in CRF patients compared with the other two groups. The plasma levels of vitamin E were diminished in CRF patients; on the contrary, the biological liquid oxidant activity (BLOA) of serum in CRF patients was significantly higher than in controls and in cataractous patients without CRF. Cataractous patients with and without CRF showed similar levels of GSH in aqueous humour; on the contrary, the content of GSSG was significantly higher in CRF patients. Our findings seem to demonstrate that CRF patients are exposed to oxidative stresses that could probably act synergistically with uraemia and carbamylation of lens proteins. This synergism could explain why CRF represents a relatively high risk factor for cataract.
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PMID:Systemic human diseases as oxidative risk factors in cataractogenesis. II. Chronic renal failure. 226 73

Clinicopathological studies were performed on 156 lenses of human senile cataract obtained by cataract operations between 1970 and 1988. It became clear that the aging influences the functional destruction of the equatorial region, the pathological changes of the bow area, and changes of the extralens environment. After operation for the atrophic type of the posterior subcapsular cataract, aftercataract easily develops on the intraocular lens and this requires treatment. Long-term observations were carried out in 180 Wistar male rats under the same laboratory condition and histological studies were performed. The similarities between the senile Wistar rat cataract and the human senile cataract indicate that the Wistar rat cataract is useful as a model for studying the human senile cataract. These rats were initially classified into six groups (control, vitamin E diet, EPC eye drops, catalin eye drops and reduced catalin eye drops). To study the effects of the agents (vitamin E, ARI, EPC, catalin, reduced catalin) on the cataract in senile Wistar rats the mean cell density of lens epithelia were measured at 2 or 3-month intervals. There were no statistically significant differences in treated groups and the control group. The results suggest that these agents affect another factor of lens apart from the proliferative activity of lens epithelial cell. Effects of anti-cataract agents were investigated using cultured lens epithelial cells. When cultured rat lens epithelial cells were incubated in medium containing selenite, super-oxide dismutase (SOD) activity and GSH in the cells markedly decreased, and GSSG was markedly increased. When cultured rabbit lens epithelial cells were incubated in medium contained selenite and glutathione, SOD activity was maintained normal level. When cultured lens epithelial cells were incubated in medium contained selenite and pirenoxin, SOD activity also maintained a normal level. These results suggest that both glutathione and pirenoxin are effective as anti-cataract agents. Cataracts in spontaneously hypertensive rats (SHR) was investigated on male of Wistar-Kyoto rats (WKY), stroke resistant SHR (SHRSR) and stroke-prone SHR (SHRSP) rats aged 3 to 9 months. Cataracts in these rats were classified as follows: Type 0: no opaciiy, Type 1: nuclear opacity, Type 2: posterior subcapsular opacity, Type 3: nuclear opacity associated posterior subcapsular opacity and Type 4: complete opacity in both lenses. Incidence of cataract in WKY was 2.6%, SHRSR, 76.8% ant SHRSP, 88.2%. Incidence of nuclear opacity was remarkably higher in SHRSP (48.5%). In SHR aged from 3 to 5 months, nuclear opacity was ahead of the appearance of posterior subcapsular opacity which was increased during aging.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Cataract--clinic and pathology]. 227 35

In this study we have investigated the oxidative metabolism of red blood cells (RBC), plasma, serum, aqueous humor, and lens of healthy subjects and of age-matched cataractous patients with and without diabetes. Reduced and oxidized glutathione (GSH GSSG) levels in RBC were similar among the three groups. Plasma levels of GSSG were higher in diabetics than in cataractous and control subjects. No differences in plasma content of GSH were noted among the three groups. The activity of the enzyme glucose-6-phosphate dehydrogenase was significantly diminished in diabetic patients. Controls and cataractous patients showed similar levels of malondialdehyde (MDA). Although not significant the MDA content in RBC from diabetics was elevated. No differences in plasma levels of vitamin E were noted among the three groups. The biological liquid oxidant activity of serum in diabetic patients was significantly higher than in controls and cataractous patients. GSH levels in aqueous humor were similar in diabetic and nondiabetic cataractous patients. The content of GSSG in aqueous humor was highest in diabetic patients. Control clear lenses showed low levels of MDA. The MDA levels in cataractous lenses from nondiabetic patients were significantly higher than those of controls. In diabetic patients the content of MDA in the lens was approximately twice as high as the cataractous values. Our results seem to demonstrate that oxidative damage could play a role in the pathogenesis of cataract in diabetes.
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PMID:Systemic human diseases as oxidative risk factors in cataractogenesis. I. Diabetes. 318 3

Previous studies have indicated that in vivo exposure to hyperbaric O2 may be associated with the development of nuclear cataract. In the present work, in vitro effects of hyperbaric O2 on rabbit lenses were investigated following culture of the lenses in an atmosphere of 99% O2 at pressures ranging between 1 and 100 atm. Treatment with O2 resulted in a significant decrease in the level of reduced glutathione (GSH) in the lenses even at the lower pressures studied (less than 8 atm). At 100 atm O2 the loss of GSH was 85% after a 3 hr exposure. At 8 atm O2 a significant drop in GSH concentration was shown to occur in the lens nucleus prior to loss of the tripeptide in the superficial cortex. O2-treated lenses became hazy in appearance, especially at the higher pressures, but did not become densely opaque. Pressures of N2 up to 100 atm had no effect on either lens transparency or on the concentration of GSH. Although oxidized glutathione (GSSG) was detected in the whole lens at pressures of O2 as low as 4 atm, no change in GSH level or evidence for GSSG accumulation was observed in the capsule-epithelium of the lens at pressures as high as 50 atm O2. Ninety percent of the GSSG present in lenses after exposure to 100 atm O2 could be reconverted to GSH by subsequent culture of the lenses under normal conditions. Exposure of lenses to 50 atm O2 produced a three-fold stimulation of hexose monophosphate shunt activity, equal to that which has been reported for treatment of lenses with 0.06 mM H2O2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Exposure of rabbit lens to hyperbaric oxygen in vitro: regional effects on GSH level. 341 15

The disposition and disposal of the -SH groups of the lens during aging and cataractogenesis have been investigated by laser Raman spectroscopy as a noninvasive microprobe in the intact living lens. In this procedure -SH and -S-S- give unique discrete Raman signals (at 2580 and 508 cm-1) that may be used to calculate relative concentrations in a very small volume of the lens. We present evidence showing an unexpected and remarkable difference with respect to these groups between the mouse lens and the lenses of guinea pig and man. The mouse lens nucleus exhibits a precipitous fall in the -SH concentration on aging from 1 to 6 months; concomitantly, there is a rise in -S-S- of comparable magnitude, indicating a direct conversion. The guinea pig lens, however, is quite different with respect to the age-dependent change in nuclear -S-S-: there is none between 6 months and 5 years. In the human lens -S-S- behaves exactly as in the guinea pig lens: the level is low and does not change with age between 9 and 65 years. With respect to nuclear -SH, these two latter species of lenses show some decrease with age but nothing like the approach to zero found in the aging mouse lens nucleus. These differences involving lenticular -SH and -S-S- appear to be correlated with the hard nucleus in the mouse lens and the softer nuclei of lenses in guinea pigs and humans. The relatively high level of -S-S- in the old but clear mouse lens does not support the idea that protein aggregation involving formation of intermolecular -S-S- bonds is necessarily an important cause of nuclear cataract. The small but significant age-related depression of -SH in guinea pig lens nuclei without any accumulation of -S-S- may be explained as a result of glutathione (GSH) oxidation and subsequent extrusion of glutathione disulfide (GSSG) by the lens. We propose that the oxidation of glutathione proceeds by reaction with protein disulfide groups to yield protein sulfhydryl (PSH) and a mixed disulfide of glutathione and protein; the mixed disulfide is capable of being reduced by glutathione reductase and NADPH, yielding the original PSH and GSSG, which is extruded from the lens. It remains to be determined if this mechanism is more active in guinea pig and human lenses than in the mouse lens.
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PMID:Disulfide bond formation in the eye lens. 386 9

1. Cataracts were developed by incubating rabbit lenses for 22hr. at 37 degrees in a culture medium containing tyrosine and tyrosinase (EC 1.10.3.1). 2. A 45% diminution in the content of GSH and significant inhibition of glucose 6-phosphate dehydrogenase (EC 1.1.1.49) activity were observed in the cataractous lenses compared with controls. 3. GSSG accumulated in both cataractous and control lenses. Significant amounts of GSSG were transported outward from the cataractous lenses and small amounts from control lenses. 4. Transport of GSSG from rabbit lens incubated in a diffusate of plasma from a naphthalene-fed rabbit was also observed. 5. GSSG was found in the aqueous humour obtained between 2 and 24hr. after feeding of naphthalene to rabbits; subsequently the GSSG in the aqueous humour decreased to almost undetectable amounts in 48hr.; in controls, GSSG was not detectable. 6. A possible mechanism of formation of experimental and senile cataract is briefly discussed.
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PMID:Cataract produced by tyrosinase and tyrosine systems in rabbitens in vitro. 497 83

The Italian island of Sardina occupies an important position on the map of glucose-6-phosphate dehydrogenase (G6PD)-deficiency distribution throughout the world, since in this region the condition is particularly frequent and severe (erythrocytes show only 0-7% of G6PD normal activity, while people result affect up to 35% depending on the district). In order to investigate the relationship between the deficiency of G6PD in erythrocytes and in lens, and cataractogenesis, we studied 2125 idiopathic cataractous and non-cataractous subjects, both G6PD-deficient and normal, males and females. Parameters investigated included incidence, distribution and type of cataracts, age at the moment of the first observation, geographical provenance, and G6PD activity in erythrocytes. Moreover, G6PD activity and glutathione (GSSG)-reducing activity was assessed in cataractous lenses obtained from deficient and normal individuals. G6PD deficiency was found to be significantly more frequent in males of the age-group 40-49 years (P = 0.025), while the frequency of G6PD deficiency was decisively lower in the older age-groups. In females, mainly heterozygotes, no evidence of such a relation was found. Cataractous lenses obtained from male patients with no G6PD activity in erythrocytes showed undetectable levels of G6PD activity, and lowered, but not extinguished, levels of GSSG-reducing activity. Cataractous lenses from heterozygous females showed intermediate levels of G6PD activity and GSSG-reducing activity. A preliminary study of 182 diabetic, G6PD-deficient and non-deficient subjects, failed to demonstrate that Sardinian variants of G6PD deficiency provide protection against cataract formation in diabetic patients.
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PMID:The relationship between glucose-6-phosphate dehydrogenase deficiency and cataracts in Sardinia. An epidemiological and biochemical study. 633 98

The mammalian lens contains an unusually high concentration of glutathione (GSH), the highest level being in the epithelium. GSH is present largely in the reduced state. The high concentration of GSH in a normal lens and the decreased concentration in most types of cataracts have led to many hypotheses on its role in cataract formation. These hypotheses are considered in the light of current evidence. GSH is synthesized and degraded in the lens. Both processes require ATP, derived largely from glycolysis. Carbohydrate metabolism is also involved in the maintenance of GSH in the reduced state. There is a direct link between the rate of formation of oxidized glutathione (GSSG) and the stimulation of the hexose monophosphate shunt through the generation of NADPH. One possible function of GSH in the lens is to maintain the thiol (SH) groups of proteins in the reduced state, thus preventing formation of high molecular weight (HMW) protein aggregates. The formation of HMW proteins in X-ray-induced cataracts through disulphide bond formation and the involvement of SH oxidation in HMW proteins isolated from human cataractous lenses suggest a role for GSH in protecting protein SH groups. GSH in the lens may also protect critical SH groups involved in regulating cation transport and permeability. Studies with mammalian lenses indicate that lowering the lens GSH concentration leads to increased permeability to cations and inactivation of Na+,K+-ATPase. A consequence of the changes in ion distribution is the inhibition of protein synthesis, which may explain the cessation of growth in cataractous lenses. GSH may also protect against oxidative damage to the lens. GSH metabolism is intimately involved in detoxification of H2O2, normally present in the aqueous humour. Lenses with impaired shunt activity or inhibited glutathione reductase are more susceptible to oxidative damage by peroxide. This may contribute to the formation of cataract.
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PMID:Metabolism and function of glutathione in the lens. 656 81

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