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)

Lens epithelial cells from normal and Nakano adult mice have been cultured for over 1 year, and the cells have retained certain differentiated characteristics. Fluorescent antibody to mouse gamma crystallin reacted with the spherical lentoid bodies which appeared approximately 2 weeks after the start of the culture. The lentoid bodies also contained cells which had few cell organelles and homogenous cytoplasms. Both gamma crystallin production and loss of cellular organelles are characteristics of differentiated fiber cells rather than epithelial cells. An inhibitor of the Na-K ATPase is responsible for the hydration and subsequent cataract formation in the Nakamo mouse. The inhibitor of the Na-K ATPase was demonstrated in the lens in culture from the Nakamo mice, but no inhibitory activity was detected in the cultures from normal mice.
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PMID:Tissue culture of lens epithelial cells from normal and Nakano mice. 13 83

A high glucose concentration in vivo or an increased glucose of glucose 6-phosphate concentration in vitro has been found to lead to the glycosylation of epsilon-amino groups of lysine residues in bovine and rat lens crystallins. In vitro, this glycosylation imparts an increased susceptibility of the crystallins to sulfhydryl oxidation. Disulfide crosslinks result in the formation of high molecular weight aggregates and an opalescence in the crystallin solutions. The addition of reducing agents prevents as well as reverses the formation of high molecular weight aggregates and the opalescence of the crystallins. These phenomena suggest a new interpretation of previous results on cataract formation and a new approach for development of drugs to prevent cataracts.
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PMID:Diabetic cataract formation: potential role of glycosylation of lens crystallins. 27 62

A differential effect on protein synthesis has been demonstrated in the lenses of galactosemic rats. During galactose cataract development the synthesis of lens crystallins is depressed, whereas that of noncrystallin proteins is unaffected. This effect correlates with the influx of Na+ and loss of K+ from the lens. Removal of the galactose diet results in a gradual recovering of crystallin synthesis to normal levels. In vitro the nuclear cataractous lenses leak crystallins into the media; however, upon 5 day's recovery no leak-out of crystallins could be detected. Both decreased synthesis and leak-out probably account for the marked loss of dry weight of cataractous lenses. These results support the hypothesis that crystallin synthesis may be affected by cation imbalance or changes concomitant with such an imbalance.
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PMID:Alterations of lens protein synthesis in galactosemic rats. 44 68

Two groups of patients suffering from cataract were investigated by the lymphocyte stimulation test. One group was tested before and the other after cataract surgery. Human (total) lens crystallins and bovine alpha crystallin were used as the antigens. Lymphocytes of healthy persons showed practically no positive stimulation with either antigen. Of the patients tested before operation 38% reacted positively with lens crystallins and 15% with alpha crystallin. This difference in sensitisation suggests a leakage of lenticular antigens other than alpha crystallin out of the lens during cataract progression. Extracapsular lens extraction caused an increase in the number of patients reacting positively with lens crystallins and alpha crystallin as compared to patients not operated upon. Intracapsular lens extraction on the other hand resulted in less sensitisation to lens crystallins as compared to patients not operated upon.
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PMID:Cell mediated immunity in relation to cataract and cataract surgery. 46 3

Control of protein synthesis is associated with changes in the ratio of intracellular Na+ to K+ in the cultured embryonic chick lens. Correlations of intracellular Na+/K+ ratios with crystallin synthesis and cataract formation in vitro suggest that the Na+/K+ ratio may have an important role in the regulation of protein synthesis during cataractogenesis.
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PMID:Regulation of protein synthesis, intracellular electrolytes and cataract formation in vitro. 56 20

Ocular lenses in Nakano mice showed marked changes in synthesis, degradation and leakage of protein during cataractogenesis. The cataract-associated changes included the differential lowering of crystallin synthesis, the cleavage of crystallin polypeptides to lower molecular weight forms and the leakage of crystallins from cultured lenses. Ouabain treatment of normal lenses induced these alterations, suggesting that changes in the intracellular levels of Na+ and K+ affect the anabolism and catabolism of protein during cataract formation.
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PMID:Differential metabolism and leakage of protein in an inherited cataract and a normal lens cultured with ouabain. 67 86

We examined 9 cataracts from maturity onset diabetics and 4 senile posterior subcapsular cataracts by scanning electron microscopy, transmission electron microscopy, immunofluorescence for crystallin proteins and actin, histochemical methods and x-ray diffraction. The cataractous regions contained spherical globules up to 20 mu in diameter, often in a fibrous matrix. Some were extracellular Morgagnian globules, apparently formed by blebbing from the cell surface; others appeared to have been formed intracellularly. The area of globular degeneration was usually 300 mu deep, but had deeper fusiform extensions. Morphological changes in the cell cytoplasm varied according to their depth in the cataract. Electron microscopy showed intracellular and extracellular globules, many of them were bounded by lipid bilayer membranes. Immunofluorescent staining showed that all the globules contained gamma-crystallin; some contained alpha- and beta-crystallins and actin. All the globules contained higher concentrations of cysteine or cystine than the surrounding lens tissue but they did not react to stains for carbohydrate or calcium. X-ray diffraction studies showed that crystalline calcium salts were absent. Globules and cavities averaged 45% of the total area in cross section. Assuming an area of cataract to be 300 micron thick and that globules 1 mu in diameter scattered, while 2--20 mu in diameter reflected light, we calculated that light passing through such a thickness would be reduced by 65%. Thus the globules could account for most of the opacity of the cataractous area. Presumably the fibrous degeneration of the cells causes enough light scattering to account for the remainder of the reduction. Cataract patients complain of decreased visual acuity, a golden halo around objects, and difficulties when driving while facing oncoming traffic at night. These probably result from light scattering. In our previous experiments, globular bodies containing gamma-crystallin were found in cells grown in tissue culture, and blebs with increased acitn content similar to Morgagnian globules were formed in tissue culture by treating differentiated rat lens cells of stage 2 by cytochalasin D (which impaired microfilament function). These results suggest the possibility of simulating in tissue culture the morphological alterations seen in the cataractous cell.
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PMID:Globular bodies: a primary cause of the opacity in senile and diabetic posterior cortical subcapsular cataracts? 69 89

The present study tested the assertion that there exists exclusively in persons with senile cataracts a serum factor capable of precipitating with gamma crystallin extract from bovine lens. The results of this work do not support this assertion without the imposition of rigid specifications regarding test solution concentrations and observation time. Among the 84 subjects tested, 2 individuals had posterior subcapsular cataracts. The precipitates resulting from incubation with serum from these individuals were similar to those resulting from incubations with serum from senile cataract patients. The present study did not confirm the existence of exclusive serum factors capable of precipitating with gamma crystallin extract in patients with senile cataracts.
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PMID:Serum factors precipitating with bovine lens extract in cataract patients and noncataract patients. 97 Aug 59

It appears that morgagnian cataract is a special form of cortico-nuclear cataract. It is assumed that the process of fibre dissolution which is encountered in cortical cataract in general is speeded up and occurs en masse in morgagnian cataract. Enzymatic degradation of membrane and crystallin fibre components could then occur to produce liquefaction of the fibres and resorption of the cortical fluid. Factors responsible for the resistance of the nucleus to this process have been discussed. The high levels of calcium in the capsule and nucleus in this form of cataract could be due to the precipitation of calcium orthophosphate in the capsule and of calcium oxalate in the nucleus.
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PMID:Morgagnian cataract. 107 Aug 81

Alpha-crystallin isolated from the peripheries of old normal or cataractous lenses appears to be identical, consisting of eleven polypeptides, five B, and six A chains. In contrast, alpha-crystallin isolated from normal six-week-old human lenses has only three major polypeptides, corresponding to B1, A1, and A2 of the old human lens protein as well as small amounts of some of the other components. Comparisons with bovine alpha-crystallin are also reported. Based on gel filtration experiments with Bio-Gel A-1.5m, two distinct populations of alpha-crystallin were found in old lens periphery, one containing species greater than 1.5 X 10(6) daltons and another of approximately 9 X 10(5) daltons. In the cataract preparations, the higher molecular weight fraction is predominant. This fraction is not present in young lenses.
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PMID:Human alpha-crystallin-III isolation and characterization of protein from normal infant lenses and old lens peripheries. 126 70


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