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 concentrations of some ribonucleoside tri- and diphosphates, adenosine-5'-monophosphate, L-lactate and pyruvate were determined in human senile cataractous lenses removed during cataract operations. Pyruvate concentrations were found to be negligible (median = 56 mumol/kg lens wet weight) in 15 human senile cataractous lenses. On the basis of correlations between the biomicroscopic appearances of the senile cataractous lenses (N = 80) and the concentrations and ratios of the metabolites in question, the following classification was found to be justified: 1. Immature cataractous lenses without anterior capsular/subcapsular opacity: high levels of ribonucleoside triphosphates (RTP), high sums of RTP, ribonucleoside diphosphates (RDP), and adenosine 5'-monophosphate (AMP) as well as high levels of L-lactate and high ratios of L-lactate in the lens/L-lactate in the aqueous. 2. Immature cataractous lenses with anterior capsular/subcapsular opacity; intermediate levels of RTP, intermediate values for the sums of RTP, RDP, and AMP, high L-lactate levels, and intermediate values of the ratios of L-lactate in the lens/L-lactate in the aqueous. 3. Totally opaque lenses, which all had extensive anterior capsular/subcapsular opacity; low values for the concentrations of lens RTP, for the sums of RTP, RDP and AMP, and for lens L-lactate. Low ratios of L-lactate in the lens/L-lactate in the aqueous.
 ...
PMID:Concentrations of some ribonucleotides, L-lactate, and pyruvate in human senile cataractous lenses with special reference to anterior capsular/subcapsular opacity. 99 18

The effect of pyruvate on the progress of galactose cataract has been studied. Pyruvate was administered topically in the form of eye drops. Such treatment was found to delay the onset of the cataractous changes. Cataract formation was studied by visual inspection with pen light, as well as with slit lamp biomicroscopy in the intact animal. The delay in the formation of cataract was associated with the preservation of the levels of lens ATP, soluble proteins and the decreased accumulation of galactitol. In vitro organ culture experiments yielded similar results.
 ...
PMID:Prevention of galactose cataract by pyruvate. 159 5

Intact rat lenses were incubated in riboflavin-containing Tyrode solution or medium-199, generating photochemically active species of oxygen and the oxidative stress measured in terms of the decrease in active accumulation of rubidium, and the fall in the levels of glutathione and ATP. Addition of pyruvate to the medium prevented the tissue against oxidative damage as evidenced by a greater accumulation of rubidium and higher levels of glutathione and ATP. Pyruvate was thus found to be effective against the toxicity of oxygen derivatives, particularly the hydrogen peroxide. In dark experiments also, conducted in glucose-free medium, the uptake of rubidium was substantially greater in the presence of pyruvate. The levels of ATP were also higher. These results, therefore, suggest that this ketoacid is beneficial to the tissue through its ability to decompose H2O2 as well through providing a metabolic support. The development of in vitro cataract under the photochemical effects of riboflavin and oxygen was also effectively thwarted by pyruvate. The results are thus potentially useful from the point of view of developing pyruvate and similar compounds as effective anticataract agents.
 ...
PMID:Photoinduction of cataracts in rat lens in vitro. Preventive effect of pyruvate. 237 72

Exposure of mice to hyperbaric oxygen leads to an inhibition of the mitotic activity in the germinative epithelium of the lens. This is followed by an eventual development of cataracts. Cataracts have also been observed in human beings treated with hyperbaric oxygen for different afflictions. The lens damage and cataract formation appears to be due to in situ generation of active radicals and other active species of oxygen. These oxygen derivatives may also contribute to the multifactorial process of senile cataract formation in human beings. This hypothesis is based on in vitro experiments with rat lenses cultured in medium generating oxygen radicals, the generation of the radicals being accomplished either photochemically or enzymatically. The ability of the lens to transport rubidium and amino acids from such a medium is adversely affected. This is a recognized index of the damage to the tissue physiology. Scavengers of active oxygen species have been found to protect against this damage. Ascorbate, present in concentrations similar to that in the primate aqueous and lens, is also protective. The studies, therefore, point to an antioxidant and perhaps an anti-cataract effect of ascorbate. Pyruvate is another agent useful in this regard.
 ...
PMID:Ascorbic acid and the eye lens. 318 90

Among aging disabilities, the one associated with the progressive decline of vision is functionally most disadvantageous. Cataracts are one of the more common causes of such visual disability. Several predisposing factors have been identified in the genesis of this disease. While it is perhaps a multifactorial process, significant developments have taken place in recent years suggesting that oxygen radicals are involved in the development of this aging manifestation. Antioxidant enzymes, such as catalase and superoxide dismutase, have been demonstrated to protect the lens cell membrane from oxidative stress as reflected by the prevention of the Na(+)-K(+)-ATPase-dependent pump deterioration due to oxyradical-dependent oxidation of its proteins and lipids. From the nutritional point of view, antioxidants such as ascorbate and vitamin E also offer significant protection to the lens against damage due to oxidative stress. Evidence regarding the protective effect of these nutrients has been based on lens organ culture studies in the presence of active oxygen, generated photochemically as well as enzymatically. The experiment involving photochemical environs simulate the status of the eye during the photopic vision. In vivo, the effectiveness of ascorbate against cataracts has been tested in rat pups developing cataracts under the oxidative influence of sodium selenite. Certain antioxidants produced metabolically also may be useful in protecting against cataracts. Pyruvate produced in glucose metabolism seems to be an important antioxidant. The efficacy of this compound has been tested within in vitro organ culture as well as in vivo, the latter experiments being done with selenite-treated rats. There is a hope that these and other nutritional and metabolic antioxidants may one day be useful in delaying or even preventing cataract formation in human beings.
 ...
PMID:Prevention of cataracts by nutritional and metabolic antioxidants. 774 71

In diabetic cataract, sorbitol pathway flux perturbs intracellular metabolism by two putative mechanisms. The osmolyte hypothesis implicates the aldose reductase enzyme, increased rate of reduction of glucose of sorbitol and reciprocal osmoregulatory depletion of organic osmolytes (myo-inositol). Redox hypothesis favors alterations in the ratios (NADP+/NADPH and/or NADH/NAD+ as the primary cause of glucose-induced aldose reductase related defects. Increase in NADH/NAD+ promotes increased oxidation of sorbitol to fructose by polyol dehydrogenase; potential normalization of this ratio by coadministration of pyruvate (which reoxidizes NADH to NAD+ via lactate dehydrogenases reaction) was investigated. Effects of exogenous pyruvate on lens polyol formation and sodium-dependent myo-inositol (MI) cotransporter using two in vitro models of sugar cataract were determined. Rat lenses were incubated for 16 h in either normal (5.5 mM) or high sugar medium, 35.5 mM glucose or 30 mM galactose. Then lens MI influx was compared to polyol, MI and fructose content. Pyruvate did not affect MI influx or sorbitol content in lenses incubated in control medium. In 35.5 mM glucose, coadministration of pyruvate maintained lens MI influx at 76% of control values vs. 43% for lenses without pyruvate. Furthermore, pyruvate treatment diminished lens sorbitol content by 50% and increased lens sugar content (myo-inositol, fructose, lactate) and media lactate levels. Lenses incubated in high galactose medium formed galactitol with a corresponding decreased MI content. Coadministration of pyruvate had no effect on either lens sugar content (galactitol, myo-inositol, fructose) or MI influx, consistent with the fact that galactitol was not metabolized to fructose. In conclusion, pyruvate did not exert a direct effect on the MI co-transporter or prevent galactitol inhibition of MI influx. Coadministration of pyruvate with high glucose altered lens metabolism and promoted reduction of pyruvate to lactate, increased fructose, decreased sorbitol, enhanced MI influx, maintained lens MI content, implicating both osmotic and redox systems.
 ...
PMID:Effect of pyruvate on lens myo-inositol transport and polyol formation in diabetic cataract. 932 7