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)

Sodium gradient-dependent 45Ca2+ transport occurred across the lens membrane both in the direction of Ca2+ uptake by inside-out vesicles and Ca2+ efflux after Ca2+ loading of right-side-out vesicles. Using the calcium ionophore, A23187, greater than 90% of the Na+ gradient-dependent Ca2+ uptake was estimated to be free Ca2+. A normal Na+ gradient was also required to maintain calcium homeostasis in the intact lens. The Na+ gradient contributed to Ca2+ efflux from lenses pre-loaded in medium containing 15 mM CaCl2. Therefore, a Na/Ca-exchange functions to control Ca efflux in rat lens, in addition to the Ca-ATPase. In the preweanling rat mature nuclear cataracts occurred by 96 h after subcutaneous injection of sodium selenite (30 nmol/g animal wt). A 3-5 fold increase of Ca2+ accompanied cataract formation. The loss of Ca2+ homeostasis can be detected by 48 h after treatment selenite treatment. At this time the initial rate of Na+ gradient-dependent Ca2+ uptake was 30% lower in lens vesicles from selenite-treated rats compared to controls. No significant reduction of Na+,K(+)-ATPase activity was detected. Altered Na/Ca-exchange may contribute directly to the loss of Ca2+ homeostasis that leads to nuclear cataract.
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PMID:Calcium efflux in rat lens: Na/Ca-exchange related to cataract induced by selenite. 132 93

The loss of calcium homeostasis in the lens is thought to play an important role in cataract formation. Although both lens Ca(2+)-ATPase and membrane lipid permeability are essential to calcium homeostasis, membrane permeability has been studied less extensively. In the present study, the calcium permeability of large unilamellar vesicles (LUVs) prepared from bovine lens cortical lipids has been characterized. When a calcium gradient had been established by the addition of CaCl2 to the external medium, calcium influx through the membrane was monitored by calcium concentration sensitive changes in Fura-2 fluorescence as a function of time. The calcium permeability coefficient, P, was 4.46 x 10(-13) cm s-1 at 37 degrees C. This value was about 4 fold higher than that for LUVs prepared from egg phosphatidylcholine and many times higher than that for LUVs prepared from sphingomyelin. These results provide a basis for future studies of factors that influence the permeability of lens cell membranes to calcium.
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PMID:Calcium permeability in large unilamellar vesicles prepared from bovine lens cortical lipids. 909 27

Compounds capable of inhibiting protein aggregation may find pharmacological applications in the treatment of a number of diseases called protein condensation diseases [Benedek (1997)], which include cataract, biliary and urinary lithiasis and certain rheumatic diseases. We examined the effect of selected compounds on heat-induced aggregation human serum albumin (HSA), IgG and lysozyme. HSA (0.2% w/v in 0.066 M sodium phosphate pH 5.3 at 22 degrees C), IgG (0.5% w/v in 0.066 M Tris pH 8.0 at 22 degrees C), and L (0.2 % w/v in 0.066 M CAPS pH 11.0 at 22 degrees C) were heated for 30 min at 70 degrees C in the presence or absence of different concentrations of the substance under examination and heat-induced aggregation of 100 microl aliquots was evaluated by measuring the absorbance at 595 nm using an automatic microplate reader. In these conditions, inhibition of aggregation could be due to an anti-denaturant effect or to interferences with the aggregation of denatured molecules, as previously described [Saso, Casini et al. (1998)]. However, this distinction may not be pharmacologically relevant when the target of the therapy is the prevention of abnormal phenomena of protein aggregation. Inorganic salts like NaCl and CaCl2 were active on the three proteins (IgG > HSA > L) but many ligands of HSA such as tryptophan, N-acetyl-tryptophan, caprylic acid, capric acid, cholic acid, deoxycholic acid, chenodeoxycholic acid, lithocholic acid and bendazac were active on their carrier but not on IgG and L, indicating that the latter proteins are more difficult to protect and that specific anti-denaturant and/or anti-aggregant compounds should be developed.
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PMID:Effect of selected substances on heat-induced aggregation of albumin, IgG and lysozyme. 992 Mar 43