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

The purpose of this study was to determine the cause of lens cataracts in hatchery trout fed diets containing white fish meal. After preliminary investigations, three experiments were conducted with fry of rainbow trout (Salmo gairdneri) that were fed practical-type diets containing either 40% herring meal (control diet) or 40% white fish meal with and without various mineral supplements. In all experiments, the trout fed herring meal grew well and had normal lenses. Those fed the diet containing white fish meal without supplement grew slowly and developed bilateral cataracts determined by using a slit-lamp biomicroscope. The severity of cataracts was increased by supplementing the diet with a mixture of minerals (phosphates and carbonates of calcium, sodium and potassium). Cataracts were prevented, however, with supplemental Na2EDTA or zinc but not by supplements of manganese, copper, iron or various other minerals. The metabolic alterations responsible for the zinc-deficiency cataract were not determined.
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PMID:Influence of dietary zinc on cataracts in rainbow trout (Salmo gairdneri). 10 82

51 patients with renal transplants were examined ophthalmologically 31,1 (1--77) months after the transplantation. 80,4 p. c. showed ocular complications: cataract formation in 43,1 p. c. of the patients examined and increased intraocular pressure values between 22 and 30 mm Hg in 3 patients are to be attributed to the systemic immunosuppressive therapy. Further ocular changes were recurrent subconjunctival haemorrhages due to increased vascular rigidity, calcium phosphate deposits in the conjunctiva due to persistant secondary hyperparathyroidism and fundus changes (pigmentary irregularities in the foveal regions, narrow arterial vessels). Although marked arterial hypertension was observed in 21 patients after the transplantation, no signs of hypertensive retinopathy could be found. Despite the high incidence of ocular complications after renal transplantation the risks of immunosuppressive therapy must be considered as tolerable: cataract formation and increased intraocular pressure do not impair the positive effect of renal transplantation on ocular functions. Regular ophthalmological control examinations of renal transplant patients are advisable.
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PMID:[Report on renal transplant patients. Ocular changes due to renal disease and immunosuppressive therapy (author's transl)]. 37 46

A family with "ant-egg" cataract in three generations is described. The cataract is congenital, probably of autosomal dominant inheritance. Light microscopy of the ant-eggs showed that they are made up of a peripheral zone of lens material and a large almost homogenous centre. Element analysis by X-ray spectrophotometry showed a high content of calcium and phosphorus in the centre. The cataract has been easy to operate on and the postoperative visual results have been good.
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PMID:Ant-egg cataract. A study of a family with dominantly inherited congenital (ant-egg) cataract, including a histological examination of the formed elements. 41 70

A 59-year-old woman with idiopathic hypoparathyroidism who had tetany and zonular cataract is described. Twelve years ago she had had a period with cramps and convulsions, followed by an absence of symptoms for several years. Judging from the distance between the opacity of cataract and the surface of the lens, the onset of the cataract was estimated to have occurred 11 years ago and the apparent cessation of cataract development 10 years ago. It is suggested that the absence of hypocalcaemic symptoms during the last 10 years was associated with an increase in serum calcium levels, possibly connected with the onset of menopause. The occurrence of hypocalcaemia was analyzed in a health-screened population of 15 903 persons. Nine of the subjects were found to have a serum calcium level of less than 2.10 mmol/l, giving a prevalence of 0.6%0. None had primary hypoparathyroidism, which illustrates the rarity of this condition.
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PMID:Hypocalcaemia with zonular cataract due to idiopathic hypoparathyroidism. With a note on the prevalence of severe hypocalcaemia in a health screening. 63 16

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 radiological diagnosis of orbital lesions can be aided by an understanding of the significance of the various kinds of calcium deposits. Orbital calcification may be metastatic or dystrophic, with ossification occurring in degenerated eye tissue in the presence of an abundant blood supply. It is the dystrophic type which is usually visualized radiographically. Intraorbital calcification had been categorized according to its configuration and location (a) ocular; (b) extraocular; and (c) extraorbital extending into the orbit on frontal radiographs. Lesions discussed include cataract, phthisis bulbi, vascular abnormalities, infection, and tumor.
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PMID:Calcification and ossification within the orbit. 82 79

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

Na,K-ATPase, an enzyme intrinsic to the membrane of most cells, is inhibited in cataract. Na,K-ATPase, activity in clear non-cataractous lenses is found predominantly in the lens epithelium. The lens fiber cells would appear to be unique, among mammalian cells in that Na,K-ATPase activity is low if not absent. The study presented here indicates that Na,K-ATPase is present, often in high concentration, but progressively more functionally compromised as the fiber cells mature. The membrane lipid environment as causative agent in the loss of normal function of Na,K-ATPase, is considered in this study. The data indicate a correlation between increasing cholesterol/phospholipid ratio, increasing phospholipase A2 activity and decreasing Na,K-ATPase activity in normal clear lenses. The phospholipase A2 activity is higher in cortex and nucleus than in the epithelium of normal bovine and human lenses. The phospholipase A2 is Ca2+ dependent and may be membrane associated.
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PMID:Na,K-ATPase and phospholipid degradation in bovine and human lenses. 131 22

A single subcutaneous dose of 30 nmol of sodium selenite per gram of body weight in 13-day-old rats resulted in posterior subcapsular cataract (PSC) after 24 hr and bilateral nuclear cataracts at 72-96 hr. Within 24 hr of treatment, a 60% decrease in lens glutathione was seen. A loss of calcium homeostasis observed by 48 hr resulted in increased lens calcium (4 mumol/g dry weight), which accompanied nuclear opacification. The iron chelator, deferoxamine (DF), was evaluated as a potential protective agent against these selenite-induced changes. Three doses each consisting of 1.1 mumol DF/g body weight were administered during the initial 24 hr of selenite exposure. Within 96 hr, all lenses from animals treated only with DF remained transparent, but 50% of these lenses showed cortical cataract at 3 wk postinjection. Concurrent administration of DF and selenite protected 80% of rats against PSC after 48 hr and 25% against nuclear cataract after 96 hr. No elevation in lens calcium occurred in the protected lenses. An additional 20% of animals were not protected fully but showed substantially less nuclear opacity than with selenite alone. They had a significant but moderate increase in lens calcium. After 3 wk (animal age, 35-40 d), cataract appeared in these "protected" lenses involving both the nucleus and cortex and loss of ion homeostasis. The glutathione content remained lower in lenses from animals treated with both selenite and DF compared with those from selenite-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Deferoxamine effect on selenite-induced cataract formation in rats. 132 98

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


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