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 evidence of sorbitol excess in the crystalline lens of alloxan-diabetic rats has led to anticipate the role of the enzyme aldose-reductase in the pathogenesis of the diabetic cataract. In addition, a number of experimental works have more recently shown the involvement of myoinositol deficiency, which probably results from the sorbitol accumulation. These metabolic pathways are most likely implicated in the pathogenesis of diabetic neuropathy and perhaps additionally in that of microangiopathy. The synthesis of several aldose-reductase inhibitors (AR inhibitors) confirmed experimentally these hypothesis. By reducing the activity of the enzyme aldose-reductase, these substances suppress the adverse metabolic consequences of polyol accumulation, myositol deficiency and dysfunction of the Na+/K+ ATPase dependent sodium activity. Although different experimentations showed that the AR inhibitors could prevent in animals the development of experimental cataract as well as the early functional or later anatomic abnormalities of the diabetic retinopathy and nephropathy, the clinical trials did not clearly support these experimental results in humans. On the other hand, the AR inhibitors were proved to exhibit some efficacy in the early stage of diabetic neuropathy and in incipient nephropathy where they delay the development of albustix positive proteinuria. However, the benefit of an early treatment with AR inhibitors should be confirmed by long term prospective studies, which could also assess the safety of these drugs in chronic administration.
 ...
PMID:[Role of polyols in the development of diabetic complications. Value of aldose-reductase inhibitors]. 141 Aug 79

The purpose of this overview is to promote an interest in understanding and reducing the possible occupational health risks of microwave radiation on the eye. Microwaves act on living tissue through two types of mechanisms, thermal and nonthermal. Lens opacities can be induced in experimental animals at relatively high intensities (power densities greater than 100 mW/cm2). For lower intensities, lens changes may depend on the cumulative dose. At "nonthermal intensities", microwaves can act as a trigger and set off changes in the living tissues (e.g. Ca++ efflux). Some cataract-causing agents (alloxan and galactose) act synergistically with microwaves. Microwaves also accelerate formation of cataracts due to diabetes. The corneal endothelium can be damaged by microwaves alone or in combination with some drugs. Microwave degeneration of retinal nerve endings and a small increase in retinal permeability were also found in animals. The effect of long-term low-intensity microwave exposure on the human lens remains poorly understood. Several reports have implicated occupational microwave exposure as a factor in increasing the rate of lens aging and retinal injury in microwave workers. In Canada, recommended microwave exposure limits are set at 25 mW/cm2 for microwave workers and at 1 mW/cm2 for the general public (both averaged over 1 minute). The Australian microwave exposure safety standard (1985) recommends pre- and post-employment eye examinations for workers.
 ...
PMID:Effects of microwave radiation on the eye: the occupational health perspective. 248 31

The author describes his findings pertaining to spontaneous diabetes mellitus in BB rats and the method and results in juvenile alloxan diabetes in neonatal and adolescent Wistar rats of his own inbreeding F8-10. The author presents also the results of attempts to treat juvenile alloxan diabetes in rats by intrafamilial renal-subscapular allotransplants of 2-5 neonatal collagenase nondigested pancreases. Six of eleven BB females developed latent or manifest insulin dependent diabetes mellitus during the third to fourth month of life. An intraperitoneal injection of alloxan to 2-5-day-old rats causes, after two months of prediabetes, latent or manifest disease, in particular in males. In one-two-month adolescent fasting F6--10 inbred rats (Wistar strain) intravenous injection of 50 mg/kg alloxan causes diabetes mellitus with hyperglycaemia (20-60 mmol/l), glycosuria, polyuria, arrested growth, development of cataract and early death due to pulmonary or intestinal infection. The author tries to prevent these sequelae and complications by insulin therapy or intrafamilial allotransplantations of 2-5 neonatal, collagenase nondigested pancreases beneath the renal capsule, using two-three--week immunosuppression with Cyclosporin A combined with Azathioprine. The author proves permanent cure, histologically and functionally, by repeated allotransplantation which, however, due to the intense thymolymphatic immunological barrier in adolescent rats is less frequent than cure repeatedly achieved by the author in adult diabetic rats.
 ...
PMID:[Spontaneous and experimental models of human juvenile diabetes mellitus]. 275 53

Male rhesus monkeys were used to elucidate the combined effect of vasectomy and diabetes on frequency and size of atherosclerotic plaques. Four groups were made: in two, bilateral vasectomy was performed, and the other two were subjected to sham vasectomy. Half of the vasectomized and sham-vasectomized monkeys were made diabetic by intravenous injection of alloxan. The animals were observed for a period of one year. Clinical examination revealed bilateral cataract in 40% of the diabetic animals. Marked hyperglycemia along with significant increase of serum triglycerides and free fatty acids was noted in diabetic monkeys. Vasectomy per se did not alter serum lipid levels and overall atherosclerotic plaque score in nondiabetic monkeys. However, the combination of vasectomy with diabetic state led to significant increase of overall atherosclerotic plaque score in coronary and renal arteries.
 ...
PMID:Frequency and size of atherosclerotic plaques in vasectomized diabetic monkeys. 287

Changes in the cation balance cause hydration and initiate the process of lens opacification. Such alterations were studied in human cataractous lenses and during the development of alloxan-induced diabetic cataract in rats by biochemical and histochemical techniques. The development of alloxan-induced cataract in rats was examined in vivo which showed cortical opacities beginning after 32 days. These opacities did progress to maturity after 64 days and finally the lenses were completely opacified after 96 days of alloxan treatment. The histochemical localization of sodium-potassium-activated adenosine triphosphatase using three different methods provided information on the possible role of this enzyme in normal and cataractous lenses. In human cataractous lenses, sodium-potassium adenosine triphosphatase activity was found to be considerably decreased, whereas no activity of this enzyme was localized in human diabetic cataractous lenses. An animal model provided evidence that an apparent decrease of sodium-potassium adenosine triphosphatase may be involved in the initiation of alloxan-induced diabetic cataract in rats.
 ...
PMID:Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. I. Cation transport and sodium-potassium-dependent ATPase. 298 22

The fruit extract of Momordica charantia Linn. was studied in Charles Foster rats of both sexes in respect of its dose-response hypoglycemia and at maximal effective dose, its influence on the development of diabetic cataract. Alloxan (120 mg/kg s.c./rat, single dose) diabetic rats with greater than 150 mg% of blood sugar were classified into four groups (n = 10) wherein two were control and the rest were test groups). In the test group, the oral dose response hypoglycemic herbal effect was found to be maximum at 4 g/kg/Day/rat when administered for 20 days. This dose was continued in the 2nd test group for a period of 2 months. Blood sugar in all the rats was estimated by microdetermination method using a dextrometer before and after therapy. The control group of rats received 2 ml of 0.9% NaCl and they developed cataract in 90 to 100 days. The herbal treated diabetics showed cataract in 140 to 180 days. Cataract formation was found to be dependant on blood sugar levels since the control group with blood sugar 307 +/- 81 (mg%) was blind 2 months earlier than herbal treated group which showed blood sugar 149 +/- 66.37 (mg%).
 ...
PMID:Effect of Momordica charantia Linn. pomous aqueous extract on cataractogenesis in murrin alloxan diabetics. 338 55

Carnitine is present in the eye tissues of the rabbit and the highest concentration is found in the lens. In streptozotocin-diabetic rats, the carnitine loss of the lens is an initial and important event. At 8 days after the induction of diabetes, the carnitine content in the rat lens was reduced by 63% compared to control. The loss of lens carnitine continued at 15 and 45 days after the induction. Total carnitine level in the serum was diminished by 15 days, and the reduction in percentage term was much lower in comparison to the loss of lens carnitine. In the rabbit after alloxan-diabetes induction, there is an extensive loss of carnitine in the lens: -85% after 4 months. The carnitine levels in the other eye tissues seem substantially unaffected. The loss of lens carnitine was present even with an inconsistent hyperglycaemia. No difference was found in serum carnitine levels between controls and alloxan-treated rabbits. The role of carnitine in lens is still unclear, but its loss may be related to the appearance of cataract. A derivative of carnitine, acetylcarnitine, might prevent the processes involved in the formation of cataracts by a pharmacological action, as has been shown for aspirin.
 ...
PMID:In experimental diabetes the decrease in the eye of lens carnitine levels is an early important and selective event. 917 53

We have measured lipid peroxidation and the activity of antioxidant enzymes in lenses of alloxan injected rats. After 12 weeks alloxan treated rats developed lens cataract. Diabetes rats had both lower lens weight and lower level of proteins in soluble fraction of lens homogenate. Alloxan treatment is associated with a significant increase of thiobarbituric acid reactive substances and the activity of antioxidant enzymes superoxide dismutase and catalase. However, diabetes decreased the activity of glutathione peroxidase in rat lenses. These results show that alloxan, which changes antioxidant status in rat lenses, may cause complications associated with diabetes.
 ...
PMID:Alloxan induced cataract in a rat. 1181 13

We have investigated the biochemical and cell biological basis of the reported beneficiary effects of the leaf extracts of the plant Ginkgo biloba, which has been used as a possible ophthalmic drug. The antioxidant, antimicrobial, anti-apoptotic and cytoprotective properties of the standardized extract called EGb761 were assayed. Chemical stresses were induced in cells using alloxan or dexamethasone, and the effect of EGb761 on them was studied using the MTT and TUNEL assays. Its ability to modulate the activities of some antioxidant enzymes was tested in vitro. In addition, cataract was induced in rats through selenite injection, and the effect of EGb761 administration on the progression of cataract was studied using slit lamp examination. Ginkgo biloba was found to be an excellent antioxidant. It readily scavenges reactive oxygen and nitrogen radicals and inhibits oxidative modifications that occur to proteins in vitro. It enters intact cells and protects them from alloxan-mediated and light-mediated stress, and the nuclear DNA from single strand breaks. It also effectively inhibits chemically induced apoptosis. It does not modulate the activities of endogenous antioxidant enzymes, nor does it have any significant antimicrobial activity. Unlike some other plant extracts, it is not phototoxic. In experiments wherein selenite cataract was induced in laboratory rats, treatment with the extract significantly retards the progression of lens opacification in vivo. Ginkgo biloba's inherent antioxidant, antiapoptotic and cytoprotective action and potential anticataract ability appear to be some of the factors responsible for its beneficial effects.
 ...
PMID:Molecular and cellular assessment of ginkgo biloba extract as a possible ophthalmic drug. 1282 96

The efficacy of Momordica charantia (MC), Eugenia jambolana (EJ), Tinospora cordifolia (TC) and Mucuna pruriens (MP) was assessed in the prevention of murine alloxan dibetic cataract. Alloxan (120 mg/kg) was used as the diabetogenic agent. While controls and diabetic controls did not receive any plant extract, treated rats received lyophilized aqueous extract of MC and EJ (200 mg/kg p.o.), alcohol extract of TC (400 mg/kg) and MP (200 mg/kg p.o.) every day until 4 months. Serum glucose concentration was assessed and cataracts examined with both the naked eye and through a slit lamp. Of the eight animals in the diabetic control group, four developed cortical cataract (stage IV) by day 90 while the remaining four developed it by day 100. The incidence rate of cataract in MC, EJ, TC and MP treated groups at 120 days was only 0, 0, 1 and 2. Oral feeding of MC, EJ, TC and MP extracts for 1 month produced a fall of 64.33%, 55.62%, 38.01% and 40.17%, respectively, in the serum glucose levels in comparison with the 48 h level. After 2 months of treatment, the respective values were 66.96%, 59.85%, 40.41% and 45.63%. MC and EJ prevented the development of cataract while the protective effect was less with TC and MP along with a significant reduction of plasma glucose levels (p < 0.001).
 ...
PMID:Prevention of experimental diabetic cataract by Indian Ayurvedic plant extracts. 1245 87


1 2 Next >>