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

Viscoelastic substances in correlation with intraocular hypotony have gained great significance in low-irritation cataract surgery within the last few years. The differences in their chemical properties, and thus in their effect on the eye, formed the grounds for a controlled clinical study comparing sodium hyaluronic acid, representing the group of glucosamine glykanes, and hydroxypropylmethyl cellulose (HPMC), representing the group of cellulose ethers. Two hundred cataract patients, excluding those suffering from diabetes mellitus, glaucoma and severe corneal damage, were examined on the 1st, 2nd and 5th postoperative day, as well as 4 weeks postoperatively. Statistically, no significant differences were found as regards IOP and postoperative anterior chamber irritation. From the economical point of view, methocel (HPMC) should be preferred to sodium hyaluronic acid in routine cataract surgery due to the lower costs.
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PMID:[Controlled clinical study of two viscoelastic substances]. 175 27

Cataract is a long-term complication of diabetes mellitus. Diabetics have increased glucosamine levels and it is possible that the non-enzymic glycosylation of the lens structural proteins by glucosamine induces conformational changes in the lens that contribute to cataract formation. Aspirin and aspirin-like analgesics may protect against glycosylation. In this paper the binding of glucosamine to bovine lens proteins and the effects of aspirin, paracetamol and ibuprofen on this reaction were investigated. Significant binding of glucosamine to the lens proteins was found. Gel-chromatography indicated that beta H-crystallin was most reactive to the amino-sugar. Of the analgesics studied, aspirin was the most effective inhibitor of glycosylation, followed by the other anti-inflammatory drug, ibuprofen. Preincubation of the lens homogenate with aspirin was no more effective at decreasing binding of glucosamine than was simultaneous incubation with aspirin. Glutathione significantly inhibited glucosamine binding. Glucosamine is active in non-enzymic glycosylation but the reaction can be inhibited by agents thought to protect against cataract.
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PMID:The non-enzymic glycosylation of bovine lens proteins by glucosamine and its inhibition by aspirin, ibuprofen and glutathione. 275 89

The capsules (with epithelial cells attached) of lenses from normal and cataractous mice (Nakano strain) were biosynthetically labeled in vitro with radioactive precursors. The labeled macromolecules were chromatographed on a Sepharose CL-4B column and analyzed by specific enzyme digestion. The incorporation of [3H]-proline and [3H]-glucosamine into macromolecules was comparable in the cataract and normal capsules, while that of [35S]-sulfate was reduced by 60% in the cataract capsules, indicating that the proteoglycan synthesis was specifically decreased in the cataract lens. Glycosaminoglycan analyses showed an increased synthesis of hyaluronic acid and decreased synthesis of heparan sulfate in the cataract capsules. It is possible that the alterations in the synthetic level and glycosaminoglycan components of proteoglycan affect the permeabilities of macromolecules to lens capsule and lead to cataract in Nakano mouse lens.
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PMID:Biosynthesis of proteoglycans by lens epithelial cells of cataractous mouse (Nakano strain). 400 75

Pathophysiological mechanisms of cataract formation include deficient glutathione levels contributing to a faulty antioxidant defense system within the lens of the eye. Nutrients to increase glutathione levels and activity include lipoic acid, vitamins E and C, and selenium. Cataract patients also tend to be deficient in vitamin A and the carotenes, lutein and zeaxanthin. The B vitamin riboflavin appears to play an essential role as a precursor to flavin adenine dinucleotide (FAD), a co-factor for glutathione reductase activity. Other nutrients and botanicals, which may benefit cataract patients or help prevent cataracts, include pantethine, folic acid, melatonin, and bilberry. Diabetic cataracts are caused by an elevation of polyols within the lens of the eye catalyzed by the enzyme aldose reductase. Flavonoids, particularly quercetin and its derivatives, are potent inhibitors of aldose reductase. Glaucoma is characterized by increased intraocular pressure (IOP) in some but not all cases. Some patients with glaucoma have normal IOP but poor circulation, resulting in damage to the optic nerve. Faulty glycosaminoglycan (GAG) synthesis or breakdown in the trabecular meshwork associated with aqueous outflow has also been implicated. Similar to patients with cataracts, those with glaucoma typically have compromised antioxidant defense systems as well. Nutrients that can impact GAGs such as vitamin C and glucosamine sulfate may hold promise for glaucoma treatment. Vitamin C in high doses has been found to lower IOP via its osmotic effect. Other nutrients holding some potential benefit for glaucoma include lipoic acid, vitamin B12, magnesium, and melatonin. Botanicals may offer some therapeutic potential. Ginkgo biloba increases circulation to the optic nerve; forskolin (an extract from Coleus forskohlii) has been used successfully as a topical agent to lower IOP; and intramuscular injections of Salvia miltiorrhiza have shown benefit in improving visual acuity and peripheral vision in people with glaucoma.
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PMID:Natural therapies for ocular disorders, part two: cataracts and glaucoma. 1130 79