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

This article examines different recruitment strategies for the VECAT Study, a 4-year, double-masked, placebo-controlled, randomized clinical trial of vitamin E in the prevention of cataract and age-related maculopathy. Five recruitment methods were employed: newspaper advertising, radio advertising, approaches to community groups, approaches via general practices, and an electoral roll mail-out. Participants (1204) from the community in Melbourne, Australia were recruited and enrolled within 15 months (age range: 55-80 years, mean 66 years; gender ratio: 57% female, 43% male). The electoral roll mail-out and newspaper advertising were the most efficient methods of recruitment in terms of absolute numbers of participants recruited and cost per participant. Recruitment for the VECAT study was successfully completed within the planned period. Although the electoral roll mail-out and newspaper advertising were the most efficient for this study, other methods may be of value for studies with different subject selection criteria.
 ...
PMID:Community-based recruitment strategies for a longitudinal interventional study: the VECAT experience. 1081 28

The preventive effect of vitamin E (Vit. E)-containing liposome instillation on cataract progression was examined in 12-month-old Wistar rats fed a 25% galactose diet. Vit. E-containing liposomes prepared with dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine (7:3 w/w) were instilled into both eyes twice a day. Lenses of galactose-fed rats showed suture accentuation at 6 months of feeding and opacities in the cortex and nuclei at 8 months. Two months of Vit. E-containing liposome instillation, starting at 6 months of galactose feeding, retarded this cataract progression. Lenses of galactose-fed rats had increased Vit. E, lipid peroxide (LPO), galactitol, and water contents and decreased reduced glutathione (GSH) content at 6 months of feeding; increased LPO, galactitol, and water contents and decreased GSH content at 8 months. Sera of galactose-fed rats had increased Vit. E and cholesterol concentrations at 6 months of feeding. The liposome instillation increased lens Vit. E content with attenuation of the increased lens LPO content and the decreased lens GSH content but did not affect the changes in lens galactitol and water contents and serum Vit. E and cholesterol concentrations. These results indicate that instilled Vit. E-containing liposomes retard cataract progression in 12-month-old rats fed a 25% galactose diet, mainly by the antioxidative and membrane-stabilizing actions of Vit. E contained in the liposomes.
 ...
PMID:Preventive effect of vitamin E-containing liposome instillation on cataract progression in 12-month-old rats fed a 25% galactose diet. 1097 28

We examined the effect of prolonged marginal ascorbic acid deficiency of the levels of antioxidants and lipid peroxide in lenses of guinea pigs in order to clarify lenticular antioxidant status under ascorbic acid deficiency. Male guinea pigs aged 4 weeks were given a scorbutic diet (20 g/animal per day) with either marginally deficient ascorbic acid (0.5 mg/animal per day) or sufficient ascorbic acid (1 g/animal per day) in drinking water for 3 and 6 months. The deficient group showed no lens opacity during the administration period. The deficient group had 62.3 and 53.9% of lenticular ascorbic acid content in the sufficient group at 3 and 6 months of ascorbic acid deficiency, respectively. There were no differences in lenticular contents of reduced glutathione and thiobarbituric acid reactive substances, an index of lipid peroxidation, between both groups at 3 and 6 months of ascorbic acid deficiency, while the deficient group tended to have higher lenticular vitamin E content than the sufficient group. The deficient group had higher serum vitamin E concentration than the sufficient group at 3 and 6 months of ascorbic acid deficiency. These results indicate that lenticular antioxidant status is maintained well in guinea pigs with prolonged marginal ascorbic acid deficiency, which may result in no cataract formation.
 ...
PMID:Effect of prolonged marginal ascorbic acid deficiency on lenticular levels of antioxidants and lipid peroxide in guinea pigs. 1133 6

Cataracts have been attributed to oxidative injury in proteins and lipids. Primary defenses that directly protect the lens against oxidative damage include small molecule antioxidants (vitamin C, vitamin E, glutathione and carotenoids) and antioxidant enzymes (superoxide dismutase, catalase, and the glutathione enzyme systems - glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase). In humans, low plasmatic levels of vitamin C, vitamin E and carotenoids have been associated with a high risk of senile cataracts. Dogs are more prone to develop cataracts. A decrease in antioxidant defenses could be responsible for increased lens oxidation and cataract development. In this study we report the levels of erythrocytic enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase) and plasma vitamin C as well as malondialdehyde, in normal and cataractous English Cocker Spaniel dogs. Plasma vitamin C levels were consistently lower in cataractous dogs (20.17 &mgr;M +/- 8.2 &mgr;M) when compared with normal dogs (24.1 &mgr;M +/- 9.4 &mgr;M). These results indicate a possibly decreased synthesis in vitamin C, leading to lower aqueous humor levels of this vitamin. Considering that vitamin C levels in the aqueous humor may be responsible for lens antioxidant maintenance, and that these levels are obtained from plasma secretion through the ciliary epithelium, decreased plasma levels may indicate a decrease in the antioxidant capacity of the aqueous humor.
 ...
PMID:Antioxidant profile of cataractous English Cocker Spaniels. 1139 47

Alpha-lipoic acid (LA) and its reduced form, dihydrolipoic acid, are powerful antioxidants. LA scavenges hydroxyl radicals, hypochlorous acid, peroxynitrite, and singlet oxygen. Dihydrolipoic acid also scavenges superoxide and peroxyl radicals and can regenerate thioredoxin, vitamin C, and glutathione, which in turn can recycle vitamin E. There are several possible sources of oxidative stress in diabetes including glycation reactions, decompartmentalization of transition metals, and a shift in the reduced-oxygen status of the diabetic cells. Diabetics have increased levels of lipid hydroperoxides, DNA adducts, and protein carbonyls. Available data strongly suggest that LA, because of its antioxidant properties, is particularly suited to the prevention and/or treatment of diabetic complications that arise from an overproduction of reactive oxygen and nitrogen species. In addition to its antioxidant properties, LA increases glucose uptake through recruitment of the glucose transporter-4 to plasma membranes, a mechanism that is shared with insulin-stimulated glucose uptake. Further, recent trials have demonstrated that LA improves glucose disposal in patients with type II diabetes. In experimental and clinical studies, LA markedly reduced the symptoms of diabetic pathologies, including cataract formation, vascular damage, and polyneuropathy. To develop a better understanding of the preventative and therapeutic potentials of LA, much of the current interest is focused on elucidating its molecular mechanisms in redox dependent gene expression.
 ...
PMID:Molecular aspects of lipoic acid in the prevention of diabetes complications. 1168 97

Oxidative stress is suspected to intervene in certain chronic diseases. Much research has been devoted to the relationship between vitamin E, a major lipid-soluble antioxidant, and certain widespread diseases. Experimental and epidemiological proof supports a protective effect of vitamin E in a number of pathological processes such as coronary heart disease, cancer, cataract, diabetes mellitus, and Alzheimer disease. Randomized clinical trials have not confirmed a beneficial effect of vitamin E supplementation on the progression of these diseases. Certain methodological biases could however have affected these studies, explaining conflicting results. These biases include inaccuracy of vitamin E intake estimates and changes in eating habits during the course of the survey. An insufficient supplementation period using an insufficient dose and inclusion of aged and high-risk patients are the main limitations of the reported clinical trials. Large scale randomized clinical trials including healthy and low-risk subjects, along with prolonged administration of high-dose natural vitamin E, associated with synergetic compounds, and testing on morphological or biological features, will allow a better understanding of the relationship between vitamin E and chronic diseases.
 ...
PMID:[Vitamin E deficiency: risk factor in human disease?]. 1190 53

Cataract is an important visual problem of older people and a substantial health care cost in many countries. Most studies investigating risk factors for cataract have been conducted in the United States, and there is less information on the possible role of dietary factors in European populations. We conducted a case-control study to investigate the association of antioxidant vitamins (vitamin C, vitamin E, vitamin A, beta-carotene, alpha-carotene, beta-cryptoxanthin, lycopene, zeaxanthin and lutein) and minerals (zinc and selenium) and risk of cataract in a Mediterranean population. Cases with cataract (343) and 334 age/sex frequency-matched controls aged 55 to 74 y were selected from an ophthalmic outreach clinic in Valencia, Spain. Participants were interviewed about their diet using a Food Frequency Questionnaire, and other information on potential confounders, such as smoking, alcohol, and education. Blood samples were analyzed by a colorimetric method for vitamin C and by reversed-phase HLPC for other blood antioxidants. Blood levels of vitamin C above 49 micromol/L were associated with a 64% reduced odds for cataract (P < 0.0001). Dietary intake of vitamins C, E and selenium were marginally associated with decreased odds (P = 0.09, P = 0.09, P = 0.07, respectively), whereas moderately high levels of blood lycopene (>0.30 micromol/L) were associated with a 46% increased odds of cataract (P = 0.04). Our results strengthen the evidence for a protective role for vitamin C on the aging lens as this effect was seen in a population characterized by high vitamin C intakes.
 ...
PMID:Vitamin C is associated with reduced risk of cataract in a Mediterranean population. 1204 50

The eye lens is subjected to many risk factors over time, which contribute to changes in its transparency, finally leading in combination to cataract development. Ultra violet (UV) radiation is regarded as one of the widespread risk factors contributing to cataract formation, for example in combination with nutritional deficiencies. Both factors possibly contribute to the high number of cataracts in the sunbelt region of the world. In this study, two essential nutritional factors were investigated in Brown Norway rats, zinc and vitamin E deficiencies, alone and in combination with UV-A and UV-B irradiation. Young female Brown Norway rats were put on a special diet for 10 weeks, either highly deficient in Zinc or in vitamin E. The diet was otherwise identical to the control diet. Two weeks after putting the animals on the diet, UV irradiation was started in some of the groups with mydriatic pupils with 3 irradiation sessions per week (UV-A 1 J/cm2; UV-B 0.2 J/cm2). Irradiation was continued until the end of the diet treatment period. Body weight and food consumption were established at weekly intervals, as well as slitlamp microscopy to monitor changes in anterior eye segment morphology. In addition changes in transparency of the cornea and lens have been monitored and evaluated with a Scheimpflug camera (Topcon SL-45) at baseline, and after 4 and 8 weeks of irradiation. After sacrifice of the animals, the lens wet weight as well as the activity of superoxide dismutase (SOD) were determined. Zinc deficiency alone led to an almost complete arrest of body weight increase. In the cornea, UV-A in combination with zinc or vitamin E deficiency did not have any interactive effects. The combination of UV-B and zinc deficiency showed subtractive instead of additive effects on corneal transparency and neovascularization. In the lens both deficiencies positively interacted with UV-A and UV-B by increasing the density of the capsular and cortical layers. The lens fresh weight was significantly lower in zinc-deficient animals additionally irradiated with UV-A or UV-B. The activity of SOD was significantly lower in the lenses of zinc- or vitamin E-deficient animals additionally irradiated with UV-B. The experiments presented clearly demonstrate that dietary zinc and vitamin E deficiencies do interact with UV radiation damage in the cornea and lens of Brown Norway rats.
 ...
PMID:Experimental evidence for interactive effects of chronic UV irradiation and nutritional deficiencies in the lens. 1206 Dec 68

Antioxidants such as vitamin C, vitamin E, and carotenoids have been reported to prevent the progression of experimentally induced cataracts. However, little is known of the effect of procyanidins, a powerful antioxidant, on cataract formation. This paper investigates the anticataract activity of grape seed extract (GSE, which contains 38.5% procyanidins) in hereditary cataractous rats (ICR/f rats). The ICR/f rats were fed a standard diet containing 0 or 0.213% GSE [0.082% procyanidins in the diet (w/w)] for 27 days. The GSE significantly prevented and postponed development of cataract formation by evaluation of slit lamp observations of the rats' eyes. Lens weight and malondialdehyde concentration in the lens and plasma cholesteryl ester hydroperoxide (ChE-OOH) level induced by CuSO4 were significantly lower in the GSE group compared with the control group. The rats were also fed for 14 days either the diet containing 0.085% procyanidin dimer to tetramer fraction (0.085% as the procyanidins), the diet containing 0.090% procyanidin pentamer to heptamer fraction (0.085% as the procyanidins), or the diet containing 0.093% procyanidin oligomers more than decamer fraction (0.085% as the procyanidins). The ChE-OOH levels in the procyanidin pentamer to heptamer and procyanidin oligomers more than decamer groups were significantly lower than in the procyanidin dimer to tetramer group. These results suggested that procyanidins and their antioxidative metabolites prevented the progression of cataract formation by their antioxidative action. The larger molecular procyanidins in the GSE might contribute this anticataract activity.
 ...
PMID:Procyanidin-rich extract from grape seeds prevents cataract formation in hereditary cataractous (ICR/f) rats. 1216 94

Oxidation of lipid, nucleic acids or protein has been suggested to be involved in the etiology of several chronic diseases including cancer, cardiovascular disease, cataract, age-related macular degeneration and aging in general. A large body of research has investigated the potential role of antioxidant nutrients in the prevention of these and other chronic diseases. This review concentrates on the following antioxidant nutrients: beta-carotene and other carotenoids, vitamin E, vitamin C and selenium. The first part of the review emphasizes the utility of biological markers of exposure for these nutrients and the relationship to dietary intake data. The second part considers functional assays of oxidative stress status in humans including the strengths and limitations of various assays available for use in epidemiologic research. A wide variety of functional assays both in vivo and ex vivo, are covered, including various measures of lipid oxidation (thiobarbituric acid reactive substances, exhaled pentane/ethane, low-density lipoprotein resistance to oxidation, isoprostanes), DNA oxidation (oxidized DNA bases such as 8-OHdG, autoantibodies to oxidized DNA, modified Comet assay) and protein oxidation (protein carbonyls). Studies that have examined the effects of antioxidant nutrients on these functional markers are included for illustrative purposes. The review concludes with a discussion of methodologic issues and challenges for studies involving biomarkers of exposure to antioxidant nutrients and of oxidative stress status.
 ...
PMID:Antioxidant nutrients and chronic disease: use of biomarkers of exposure and oxidative stress status in epidemiologic research. 1261 79


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>