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)

In the anterior segment of the mammalian eye, the ocular ciliary epithelium produces the aqueous humor, a fluid that nourishes and protects the avascular tissues from oxidative stress. This report details the results of a study of molecular cloning, sequencing, and expression of plasma glutathione peroxidase (GPx-P) from the bovine ocular ciliary epithelium. The bovine GPx-P cDNA contains an open reading frame of 226 amino acids with a calculated molecular weight of 24,860. The corresponding amino acid sequence showed an overall identity of 88% with the human GPx-P, 88.5% with the rat GPx-P, and 46.4% with the cellular bovine glutathione peroxidase (GPx-1). The levels of GPx-P and GPx-1 transcripts in ocular tissues were analyzed and the ciliary epithelium was found to express the highest levels of GPx-P transcripts in human and bovine eyes, whereas the cornea of calf eyes expressed the highest levels of GPx-1 transcripts. Surprisingly, the lens, on which oxidants have profound effects leading to cataract formation, expressed the lowest levels of GPx-P and GPx-1 transcripts in human donor eyes. These results provide new evidence of differential gene expression of the GPx-P and GPx-1 forms in the mammalian eye and stresses the functional role of the ocular ciliary epithelium in protecting the anterior segment of the eye from oxidative damage.
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PMID:Cloning of the bovine plasma selenium-dependent glutathione peroxidase (GP) cDNA from the ocular ciliary epithelium: expression of the plasma and cellular forms within the mammalian eye. 826 11

Selenium biochemistry is reviewed in respect to its presumed relevance to age-related ocular diseases. Selenium is an essential trace element that exerts its physiological role as selenocysteine residue in at least 25 distinct selenoenzymes in mammals. Lack of GPx-1 due to alimentary selenium deprivation has been inferred to induce cataract in rats and was demonstrated to cause cataracts in mice by targeted gene disruption. The role of other selenoproteins in the eye remains to be worked out. Selenium in excess of the tiny amounts required for selenoprotein synthesis is toxic in general and causes cataracts in experimental animals. Clinical evidence for a protective role of selenium in the development of cataract, macula degeneration, retinitis pigmentosa or any other ocular disease is not available, likely because suboptimum selenium intake, as it may result from unbalanced diet, does not cause any pathologically relevant selenium deficiency in the eye. At present, there is neither theoretical nor an empirical basis to expect beneficial effects of selenium supplementation beyond the dietary reference intakes of 55 microg/day in the context of ocular diseases.
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PMID:Selenium, selenoproteins and vision. 1560 19

Selenite cataract, as an experimental animal model of nuclear cataract to mimic human senile cataract, is produced only when overdose selenite is injected to neonatal rats before eyelid opening. To clarify the cause of age differences on selenite cataract formation in rats, mRNA expression of GPx1, MsrA and MsrB1, as well as GPx activity in Wistar rat lens at different ages were assayed, level of lipid peroxidation, extent of lens damage induced by sodium selenite and barricade function of blood-retinal barrier (BRB) were investigated. The results showed that mRNA expressions and activity of antioxidant enzymes in neonatal rat lens before eyelid opening were the highest and then decreased with age, and revealed by transmission electron microscopy (TEM) using lanthanum hydroxide as tracer that higher selenite content entering eyes injured lens and resulted in cataract formation for immature BRB before eyelid opening, moreover, a little selenite content entering eyes was not enough to induce cataract formation after eyelid opening because of mature BRB.
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PMID:Effect of blood-retinal barrier development on formation of selenite nuclear cataract in rat. 2319 26