Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of heterozygous galactokinase deficiency in the development of presenile cataracts is presently undetermined. Erythrocyte galactokinase activity was measured from 95 normal Caucasian subjects and from 39 Caucasian patients who had developed idiopathic bilateral cataracts between ages 20 and 55. The diagnosis of heterozygous galactokinase deficiency was based on the following criteria: galactokinase activity more than 2.0 SD below the control population mean; when available, familial evidence for heterozygous galactokinase activity was used as additional evidence. Three of 39 patients (1/13) with cataracts were found to be carriers of the galactokinase deficiency allele (P less than 0.001). Two heterozygotes had high dietary galactose intake suggesting a possible relationship between a high galactose diet and cataract formation. Dietary information was unavailable for the third heterozygote. We conclude that there is a high prevalence of heterozygous galactokinase deficiency existing in patients less than 55 yr of age with cataracts, and recommend that adults at risk restrict their consumption of dairy products.
 ...
PMID:Cataracts in patients heterozygous for galactokinase deficiency. 394 70

The possibility that vitamin E or other antioxidants might prevent cataracts was tested by incubating rat lenses in vitro in galactose-enriched medium or by treating rats fed a diet containing 50% galactose (w/w). The vitamin E was added to the medium at 2.4 microM, and to the diet at a level of 5 g kg-1 diet. In vitro, lenses incubated with 55.6 mM galactose underwent globular degeneration, which was partially prevented by addition of vitamin E (2.4 microM). Even in such vitamin E-protected lenses, which appeared clear, many small globules could be seen in the region of interdigitation at the 'corners' where hexagonal cells intersected. In vivo, in dietary experiments, a dense nuclear opacity of the lens was observed after approximately 5 weeks; unlike diabetic cataracts, this was not prevented by the addition of vitamin E to the diet. The extensive globular degeneration observed was typical of that found in long-term (21-week diabetic) cataracts. Although no significant difference in cataract incidence was observed, the extent of damage in vitamin E-treated rat lenses appeared to be less. The difference in effectiveness of vitamin E in galactose-induced cataracts, as compared to diabetic cataracts, is tentatively ascribed to (1) the more severe osmotic stress expected from the products of the aldose reductase pathway for galactose and (2) the greater depletion of reduced pyridine nucleotides (NADPH + NADH) expected of galactose as compared to glucose.
 ...
PMID:Modelling cortical cataractogenesis VII: Effects of vitamin E treatment on galactose-induced cataracts. 397 62

With a fixed time period of galactose feeding, the rate of appearance of lenticular opacities depended on the severity of galactosemia, while with a fixed amount of galactose fed, the rate was time dependent. The capacity of tolrestat, a structurally novel inhibitor of aldose reductase (AR), to control cataract development was assessed in rats fed 30-50% galactose with the diet for 7 to 277 days. In rats fed 30% galactose for 31 days, the controlling effect of tolrestat was dose dependent, and no cataracts were detected at a dose of 35 mg/kg/day. In rats given tolrestat with the diet for 14 days, then rendered severely galactosemic with a diet containing 50% galactose, and subjected to continued treatment with tolrestat at a dose of 43 mg/kg/day, no changes were detected by slit-lamp microscopy after 207 days. The preventive effect was also dose dependent. In view of the established similarity in the pathogenesis of galactosemic and diabetic cataracts, the results obtained with tolrestat support its potential for controlling cataract development in diabetics.
 ...
PMID:Prevention of cataract development in severely galactosemic rats by the aldose reductase inhibitor, tolrestat. 398 36

We have demonstrated an increase in activity of arylsulfatase A and B during galactose induced cataract development in rats. Our recent investigation shows that acid phosphatase activity, which increases substantially during galactose cataract development in rats, could be contained to near normal level if Sorbinil, an aldose reductase inhibitor, was fed along with galactose to the rat. We have observed that the activity of other lysosomal enzymes, arylsulfatase A and/or B, also increases during galactose cataractogenesis. In the present report, we provide information with regards to the effect of Sorbinil on the activity of these enzymes during cataractogenesis. A modified Hopsu-Havu and Helminen method (1974) with p-nitrocatecholsulfate as substrate was used for localization of both arylsulfatase A and B; and the method of Hara et al. (1979) was utilized to obtain quantitative data on the level of arylsulfatase A and B activity. Ultrastructural cytochemistry shows that arylsulfatase activity in all lenses was primarily localized in epithelial cells in lysosomes with very little or no activity in cortical fibers. The number of arylsulfatase positive lysosomes and the activity level of these enzymes increased with the progression of cataract development. Galactose induced damage to lens morphology and increase in activity of arylsulfatase A and B was inhibited by inclusion of 50mg/Kg (diet) Sorbinil in the galactose containing cataractogenic diet. However, Sorbinil had no significant effect on the enzyme activity following the establishment of mature cataracts.
 ...
PMID:Ultrastructural cytochemistry: effect of Sorbinil on arylsulfatases in cataractous lenses. 402 88

During the last 10-15 years, investigations into the biology and biochemistry of the lens have demonstrated that the age changes observed cannot be the only cause of the formation of senile cataract. The various types of opacities and the wide age range in which they begin indicate a multifactorial origin involving endogenous and exogenous risk factors. Initial epidemiological studies have identified certain risk factors. Experimental cataract research is able to elucidate possible damaging mechanisms by using cataract models, for instance, the cataracts caused by excess carbohydrate (galactose, glucose), naphthalene application, ionizing rays, or by additional cocataractogenics, thus indicating steps for countermeasures. Taking (true) diabetic cataract of rats after Streptozotocin injection as an example, the efficacy of aldose reductase inhibitors is shown. Even if additional cataractogenic factors such as naphthalene and X-rays are applied, diabetic lens opacities can be prevented completely. Damage by naphthalene is due to an increased oxidative change in the lens protein. Several substances promoting the antioxidative capacity of the lens, thereby inhibiting cataract formation, are already available. Preclinical or clinical studies have demonstrated the efficacy of only a few of the commercially available anticataract drugs. The results of animal experiments presented here may well represent a basis for the development of really effective anticataract drugs.
 ...
PMID:[What possibilities exist to modify cataract development on the basis of current biochemical knowledge? Where can drugs act?]. 404 54

Partial deficiencies of the enzymes of galactose metabolism can be associated with cataract, both directly and through maternal effects during pregnancy on enzymatically normal children. However, the associations are modest, variable and not obviously expressing cause and effect. We have recorded ophthalmological and biochemical observations including oral galactose tolerance on families with established enzyme deficiencies and/or cataracts, including possible effects during pregnancy. With the partial disorders a simple relationship between the extent of biochemical abnormality and the risk of cataract is not apparent and the association may be substantially coincidental. Cataract is common, and the attractive possibility that expression is significantly due to heterozygous or lesser deficiency of the enzymes of galactose metabolism, amenable to early dietary control of children or mothers at risk, is on present evidence not well supported.
 ...
PMID:Direct and maternal aspects of the risk of cataract with partial disorders of galactose metabolism. 406 58

Protein deficiency, a frequently encountered nutritional disorder of developing countries is known to affect the proliferative and synthetic activities of several cell systems. But neither all the organs are affected at the same time nor at the same rate. The lens, which is an unique organ has been shown to suffer in protein malnutrition but without any clinically discernible changes. Clinical evidence suggests, early onset of senile cataract in underdeveloped countries is possibly due to protein deficiency. In the present investigation, it has been shown that addition of small concentrations of galactose to the diet readily induces cataracts in protein-deficient rats. This therefore supports the contention that protein deficiency alone may not produce morphological changes but exogenous or endogenous cataractogenic insults, may produce lenticular opacification in the protein-deficient state.
 ...
PMID:Interaction of galactose and dietary protein deficiency on rat lens. 406 72

The effect of a 30% galactose diet on the progression of X-ray-induced cataract in mice was evaluated by following morphological changes as seen by light and transmission electron microscopy in different regions of the lens. Lens opacities as observed with the slit-lamp biomicroscope developed at a slower rate in galactose-fed animals than in those on a normal diet. The protective effect of galactose on X-ray cataract was seen whether galactose feeding was initiated either 1 week before or after exposure to X-ray. At 4 months after X-ray approximately 50% of galactose-fed animals had mature cataracts, compared to 100% in the control group. Similarly, at two weeks after exposure to X-ray, before any lens opacities were observed, morphological changes were more severe in the control group; cells in the meridional row were more disorganized in the control than in the galactose-fed groups. However, the progression of mature cataracts in the two galactose-fed groups were not significantly different. Since free radicals produced by X-ray are thought to be short-lived, the protective effect of galactose feeding after X-ray was unexpected, raising the possibility that some of the active species may be long-lasting. The nature of such radicals, if any, is unknown and remains to be investigated.
 ...
PMID:Further observations on the effect of galactose on the development of X-ray-induced cataract in mice. 408 79

WE HAVE TAKEN ADVANTAGE OF A NEWLY ASSIMILATED PRINCIPLE IN NUTRITION: no nutrient by itself should be expected to prevent or cure any disease; nutrients as such always work cooperatively in metabolism as a team.By feeding galactose-containing diets to young rats, cataracts are regularly produced. When, however, we furnished galactose-fed animals with what may be considered a well balanced, full team of nutrients, cataract prevention was accomplished. On four galactose-containing diets supplied with a full team of nutrients, not a single cataract developed in 24 rats (48 eyes). On four diets using the same dietary galactose challenge, accompanied with inadequate nutritional teams, 47 out of 48 eyes developed cataracts. Diets of intermediate quality induced the development of intermediate numbers of cataracts. Cataracts once formed were regressed slowly and incompletely by shifting the animals to a diet similar to that which had previously been found to protect against cataract formation. The significance of these findings for nutritional research and for attacks on the problems of human cataracts and other ailments is discussed.
 ...
PMID:The nutritional teamwork approach: prevention and regression of cataracts in rats. 453 Feb 92

Rats kept on an exclusive diet of yogurt avidly ate the yogurt, grew at a normal rate, were normally active, mated, conceived, and gave birth to normal, healthy litters. However, all of the rats developed cataracts. Cataracts appeared in young rats 2 to 3 months, and in adult rats 4 to 6 months, after initiation of the yogurt diet. Cataracts first manifested themselves in small vacuoles at the periphery of the lens and then in small striae extending toward the center of the lens. These striae progressively became longer, more coarse, and numerous until they coalesced, finally forming a mature white lens. The high content of galactose in commercially available yogurt could account in full for appearance of cataracts in 100 percent of the experimental animals. The cataracts appear to be the same as those produced by diets with a high content of galactose.
 ...
PMID:Cataracts produced in rats by yogurt. 544 70


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>