Prevention of cataract by pyruvate in experimentally diabetic mice

Advantages of omics approaches for elucidating metabolic changes in diabetic peripheral neuropathy

Various animal and cell culture models of diabetes mellitus (DM) have been established and utilized to study diabetic peripheral neuropathy (DPN). The divergence of metabolic abnormalities among these models makes their etiology complicated despite some similarities regarding the pathological and neurological features of DPN. Thus, this study aimed to review the omics approaches toward DPN, especially on the metabolic states in diabetic rats and mice induced by chemicals (streptozotocin and alloxan) as type 1 DM models and by genetic mutations (MKR, db/db and ob/ob) and high-fat diet as type 2 DM models. Omics approaches revealed that the pathways associated with lipid metabolism and inflammation in dorsal root ganglia and sciatic nerves were enriched and controlled in the levels of gene expression among these animal models. Additionally, these pathways were conserved in human DPN, indicating the pivotal pathogeneses of DPN. Omics approaches are beneficial tools to better understand the association of metabolic changes with morphological and functional abnormalities in DPN.

Concentrations of glucose metabolites in the aqueous humour of diabetic cataract eyes

PURPOSE

Glucose metabolism underpins diabetic cataracts (DCs), but the relationship between the two remains unclear. Here, we tested the aqueous humour (AH) of patients with DCs to elucidate glucose metabolite levels.

METHODS

In this study, aqueous humour (AH) samples were collected preoperatively from DC eyes (n = 37) and age-related cataract eyes (n = 37) from 74 patients (74 eyes) undergoing uncomplicated cataract surgery. The content of glucose, pyruvate, L-lactate were detected by biochemical methods and advanced glycation end-products (AGEs) was detemined using enzyme-linked immunosorbent assay (ELISA) technique. Furthermore, the ratios of glucose/pyruvate and L-lactate/pyruvate in the AH were calculated. In addition, we calculated the correlation between glucose levels and AGEs in the AH.

RESULTS

The concentrations of glucose, pyruvate and AGEs in the DC group were higher than those in the control group. Significantly lower levels of L-lactate in the AH were found in the DC group. We calculated the glucose/pyruvate ratio and the L-lactate/pyruvate ratio in the AH, which showed that glucose metabolism was changed in the AH from DC patients. Interestingly, we observed that AGEs in the AH were significantly correlated with increased anterior chamber glucose permeability. A stronger correlation was found in the subgroups of male patients, younger patients, and patients with poor glycaemic control status.

CONCLUSIONS

Comparison of the levels of glucose metabolism-related products in the AH in the DC group highlight a potential pathological mechanism for DC from a glucose metabolism perspective. The findings indicated an alteration in the metabolic pathways of energy metabolism and amino acids in the AH of DC patients.

Role of sodium pyruvate in maintaining the survival and cytotoxicity of Staphylococcus aureus under high glucose conditions

Glucose is a crucial carbon source for the growth of Staphylococcus aureus, but an excess of glucose is detrimental and even leads to cell death. Pyruvate, the central metabolite of glycolysis, has been shown to have anti-inflammatory and antioxidant properties. This study aimed to investigate the protective effect of pyruvate on S. aureus under high glucose conditions. Sodium pyruvate greatly increased the cytotoxicity of S. aureus strain BAA-1717 to human erythrocytes and neutrophils in vitro. However, the cytotoxicity and survival of S. aureus were significantly reduced by high glucose, which was restored to normal levels by the addition of sodium pyruvate. The expression of hlg and lukS in S. aureus was higher in the LB-GP cultures than that in LB-G cultures, but there was no significant difference in cytotoxicity between LB-GP and LB-G cultures. Furthermore, the hemolytic activity of S. aureus supernatants could be inhibited by the cell-free culture medium (CFCM) of LB-G cultures, suggesting that high levels of extracellular proteases were presence in the CFCM of LB-G cultures, resulting in degradation of the hemolytic factors. The expression of sarA, which negatively regulates extracellular protease secretion, was higher in LB-GP cultures than that in LB-G cultures. Additionally, sodium pyruvate increased acetate production in S. aureus, which helps maintain cell viability under acidic environment. In conclusion, pyruvate plays an important role in the survival and cytotoxicity of S. aureus under high glucose conditions. This finding may aid in the development of effective treatments for diabetic foot infections.

Role of pyruvate in maintaining cell viability and energy production under high-glucose conditions

Pyruvate functions as a key molecule in energy production and as an antioxidant. The efficacy of pyruvate supplementation in diabetic retinopathy and nephropathy has been shown in animal models; however, its significance in the functional maintenance of neurons and Schwann cells under diabetic conditions remains unknown. We observed rapid and extensive cell death under high-glucose (> 10 mM) and pyruvate-starved conditions. Exposure of Schwann cells to these conditions led to a significant decrease in glycolytic flux, mitochondrial respiration and ATP production, accompanied by enhanced collateral glycolysis pathways (e.g., polyol pathway). Cell death could be prevented by supplementation with 2-oxoglutarate (a TCA cycle intermediate), benfotiamine (the vitamin B1 derivative that suppresses the collateral pathways), or the poly (ADP-ribose) polymerase (PARP) inhibitor, rucaparib. Our findings suggest that exogenous pyruvate plays a pivotal role in maintaining glycolysis–TCA cycle flux and ATP production under high-glucose conditions by suppressing PARP activity.

Application of Vitamin E + Coenzyme Q Therapy During FAKO + IOL Implantation

Introduction

Cataract surgery is a widely used procedure around the world. After cataract surgery, one of the important points is that oxidative stress may cause postoperative corneal edema and vision loss.

Aim

In this study, we aim to reduce the oxidative stress and related conditions that may develop during intraoperative and postoperative FAKO + IOL implantation.

Material and Methods

Total amount of 32 patients with cataract were included to the study. The patients were classified as two groups randomly and the same surgical procedure was applied to the patients in both groups, except using visudrop. Group I was defined as a control group and routine FAKO + IOL implantation surgery was performed. In Group II, after the sideport was opened at the beginning of the operation, 0.5 cc visudrop (coenzyme q + vitamin E + hypermellosis) was given to the anterior camara. After the operation, 0.5 cc visudrop was also given to the anterior camara. Postoperative examination findings were compared statistically.

Results

In Group II, postoperative 1st day and postoperative 7th day visual acuities were significantly higher than in Group I. In Group II, postoperative 1st day and postoperative 7th day visual acuity increments were significantly higher than in Group I. In Group I, postoperative 1st day and 7th day pachymetry value increments were significantly higher than in Group II.

Conclusion

Using visudrop during the FAKO + IOL implantation may be an effective method for postoperative corneal edema and vision.

The Contribution of Fluoride to the Pathogenesis of Eye Diseases: Molecular Mechanisms and Implications for Public Health

This study provides diverse lines of evidence demonstrating that fluoride (F) exposure contributes to degenerative eye diseases by stimulating or inhibiting biological pathways associated with the pathogenesis of cataract, age-related macular degeneration and glaucoma. As elucidated in this study, F exerts this effect by inhibiting enolase, τ-crystallin, Hsp40, Na⁺, K⁺-ATPase, Nrf2, γ -GCS, HO-1 Bcl-2, FoxO1, SOD, PON-1 and glutathione activity, and upregulating NF-κB, IL-6, AGEs, HsP27 and Hsp70 expression. Moreover, F exposure leads to enhanced oxidative stress and impaired antioxidant activity. Based on the evidence presented in this study, it can be concluded that F exposure may be added to the list of identifiable risk factors associated with pathogenesis of degenerative eye diseases. The broader impact of these findings suggests that reducing F intake may lead to an overall reduction in the modifiable risk factors associated with degenerative eye diseases. Further studies are required to examine this association and determine differences in prevalence rates amongst fluoridated and non-fluoridated communities, taking into consideration other dietary sources of F such as tea. Finally, the findings of this study elucidate molecular pathways associated with F exposure that may suggest a possible association between F exposure and other inflammatory diseases. Further studies are also warranted to examine these associations.

Protective activity of pyruvate against vanadium-dependent cytotoxicity in Chinese hamster ovary (CHO-K1) cells

With increasing human exposure to vanadium-containing compounds and growing concern over their impact on human health, identification of safe methods for efficient treatment of vanadium poisoning may be of value. In this study, using Chinese hamster ovary (CHO-K1) cells, we show that the toxicity of vanadyl sulphate (VOSO₄) is mitigated in the presence of sodium pyruvate. The exposure of CHO-K1 cells to 100 μM VOSO₄ for 48 h induced significant cytotoxicity (measured with a resazurin assay) and elevation of the contents of malondialdehyde (MDA), a lipid peroxidation product, in the examined cells. When added simultaneously with VOSO₄ to the culture medium, pyruvate (4.5 mM) reduced VOSO₄-mediated cytotoxicity by twofold and inhibited MDA formation. Phase-contrast microscopy confirmed that the general morphology of cell cultures treated with 100 μM VOSO₄ and 4.5 mM pyruvate was improved compared to VOSO₄-only treated cells. The two-way analysis of variance revealed that the reduction of the adverse effects of VOSO₄ in the presence of pyruvate was due to the independent action of pyruvate as well as antagonistic interaction between VOSO₄ and pyruvate. From these data, it can be concluded that the pyruvate treatment may play a beneficial role in reducing vanadium-triggered health hazards.

Effect of coffee (caffeine) against human cataract blindness

Previous biochemical and morphological studies with animal experiments have demonstrated that caffeine given topically or orally to certain experimental animal models has significant inhibitory effect on cataract formation. The present studies were undertaken to examine if there is a correlation between coffee drinking and incidence of cataract blindness in human beings. That has been found to be the case. Incidence of cataract blindness was found to be significantly lower in groups consuming higher amounts of coffee in comparison to the groups with lower coffee intake. Mechanistically, the caffeine effect could be multifactorial, involving its antioxidant as well as its bioenergetic effects on the lens.

Kinetics of glycoxidation of bovine serum albumin by methylglyoxal and glyoxal and its prevention by various compounds

The aim of this study was to compare several methods for measurement of bovine serum albumin (BSA) modification by glycoxidation with reactive dicarbonyl compounds (methylglyoxal ‒ MGO and glyoxal ‒ GO), for studies of the kinetics of this process and to compare the effects of 19 selected compounds on BSA glycation by the aldehydes. The results confirm the higher reactivity of MGO with respect to GO and point to the usefulness of AGE, dityrosine and N′-formylkynurenine fluorescence for monitoring glycation and evaluation of protection against glycation. Different extent of protection against glycation induced by MGO and GO was found for many compounds, probably reflecting effects on various stages of the glycation process. Polyphenols (genistein, naringin and ellagic acid) were found to protect against aldehyde-induced glycation; 1-cyano-4-hydroxycinnamic acid was also an effective protector.

Regulation of pyruvate metabolism and human disease

Pyruvate is a keystone molecule critical for numerous aspects of eukaryotic and human metabolism. Pyruvate is the end-product of glycolysis, is derived from additional sources in the cellular cytoplasm, and is ultimately destined for transport into mitochondria as a master fuel input undergirding citric acid cycle carbon flux. In mitochondria, pyruvate drives ATP production by oxidative phosphorylation and multiple biosynthetic pathways intersecting the citric acid cycle. Mitochondrial pyruvate metabolism is regulated by many enzymes, including the recently discovered mitochondria pyruvate carrier, pyruvate dehydrogenase, and pyruvate carboxylase, to modulate overall pyruvate carbon flux. Mutations in any of the genes encoding for proteins regulating pyruvate metabolism may lead to disease. Numerous cases have been described. Aberrant pyruvate metabolism plays an especially prominent role in cancer, heart failure, and neurodegeneration. Because most major diseases involve aberrant metabolism, understanding and exploiting pyruvate carbon flux may yield novel treatments that enhance human health.

Molecular strategies to prevent, inhibit, and degrade advanced glycoxidation and advanced lipoxidation end products

The advanced glycoxidation end products (AGEs) and lipoxidation end products (ALEs) contribute to the development of diabetic complications and of other pathologies. The review discusses the possibilities of counteracting the formation and stimulating the degradation of these species by pharmaceuticals and natural compounds. The review discusses inhibitors of ALE and AGE formation, cross-link breakers, ALE/AGE elimination by enzymes and proteolytic systems, receptors for advanced glycation end products (RAGEs) and blockade of the ligand-RAGE axis.

Role of ultraviolet irradiation and oxidative stress in cataract formation-medical prevention by nutritional antioxidants and metabolic agonists

PURPOSE

Cataract is a significant cause of visual disability with relatively high incidence. It has been proposed that such high incidence is related to oxidative stress induced by continued intraocular penetration of light and consequent photochemical generation of reactive oxygen species, such as superoxide and singlet oxygen and their derivatization to other oxidants, such as hydrogen peroxide and hydroxyl radical. The latter two can also interact to generate singlet oxygen by Haber-Weiss reaction. It has been proposed that in addition to the endogenous enzymatic antioxidant enzymes, the process can be inhibited by many nutritional and metabolic oxyradical scavengers, such as ascorbate, vitamin E, pyruvate, and xanthine alkaloids, such as caffeine.

METHODS

Initial verification of the hypothesis has been done primarily by rat and mouse lens organ culture studies under ambient as well as ultraviolet (UV) light irradiation and determining the effect of such irradiation on its physiology in terms of its efficiency of active membrane transport activity and the levels of certain metabolites such as glutathione and adenosine triphosphate as well as in terms of apoptotic cell death. In vivo studies on the possible prevention of oxidative stress and cataract formation have been conducted by administering pyruvate and caffeine orally in drinking water and by their topical application using diabetic and galactosemic animal models.

RESULTS

Photosensitized damage to lens caused by exposure to visible light and UVA has been found to be significantly prevented by ascorbate and pyruvate. Caffeine has been found be effective against UVA and UVB. Oral or topical application of pyruvate has been found to inhibit the formation of cataracts induced by diabetes and galactosemia. Caffeine has also been found to inhibit cataract induced by sodium selenite and high levels of galactose. Studies with diabetes are in progress.

CONCLUSIONS

Various in vitro and in vivo studies summarized in this review strongly support the hypothesis that light penetration into the eye is a significant contributory factor in the genesis of cataracts. The major effect is through photochemical generation of reactive oxygen species and consequent oxidative stress to the tissue. The results demonstrate that this can be averted by the use of various antioxidants administered preferably by topical route. That they will be so effective is strongly suggested by the effectiveness of pyruvate and caffeine administered topically to diabetic and galactosemic animals.

Prevention of cataract in diabetic mice by topical pyruvate

Background:

It has been previously reported that oral administration of sodium pyruvate inhibits oxidative stress and cataract formation in diabetic animals. With a view to exploring the clinical usefulness of these findings, this study examined its preventive effect when administered topically as an eye drop.

Methods:

Diabetes was induced by intraperitoneal injections of streptozotocin. At the onset of diabetes, an eye drop preparation containing 2.5% sodium pyruvate was administered six times a day at 90-minute intervals. Treatment was continued for 6 weeks. Cataract formation was monitored ophthalmoscopically after mydriasis with 1% tropicamide eye drops. Subsequently, the treated and untreated diabetic animals and the age-matched normal controls were euthanized, their eyes enucleated, and the lenses isolated for biochemical assessment of protein glycation and glutathione levels.

Results:

Treatment with pyruvate eye drops was found to be significantly effective in inhibiting protein glycation. Glutathione levels were also better maintained. In addition, ophthalmoscopic examination revealed that the incidence of cataract in the pyruvate-treated group was only 12% as compared with the untreated diabetics in whom the incidence was 73%. Cataracts at this stage were largely equatorial.

Conclusion:

The results demonstrate that topical application of pyruvate can potentially be useful in attenuating or preventing cataract formation induced by diabetes and other conditions of oxidative stress.

Inhibition of glycolysis in the retina by oxidative stress: prevention by pyruvate

Intraocular generation of reactive oxygen species (ROS) with consequent oxidative stress has been shown to be a significant factor in the pathogenesis of many vision-impairing diseases such as cataracts and retinal degenerations. Previous studies have shown that pyruvate can inhibit such oxidative stress. This is attributable to its property of scavenging various ROS and consequently inhibiting many of the apparent toxic reactions such as lipid peroxidation and loss of tissue thiols. It is hence expected that ROS will have an adverse effect on tissue metabolism also. The present investigations were hence undertaken to study the possibility that while scavenging ROS, the compound could be effective also in preventing the inhibition of tissue metabolism as well. Since glycolysis constitutes the major bioenergetic source of the retina, the objective of the present studies was to ascertain if the effects of pyruvate are indeed reflected in the maintenance of this pathway even when the tissue is exposed to ROS. This hypothesis was examined by incubating retinal explants in ROS-generating medium in the absence and presence of pyruvate and measuring (3)H(2)O generated from 5-(3)H glucose. In addition, the lactate generated was also measured. As hypothesized, ROS-induced inhibition of glycolysis indexed by the decrease in (3)H(2)O as well as lactate formation was significantly prevented by pyruvate. This effect was also reflected by the elevation of NAD/NADH ratio, a major pacemaker of glycolysis.

Advances in pharmacological strategies for the prevention of cataract development

Cataractous-opacification of the lens is one of the leading causes of blindness in India. The situation can be managed by surgical removal of the cataractous lens. Various pharmacological strategies have been proposed for the prevention and treatment of cataract. Information on possible benefits of putative anticataract agents comes from a variety of approaches, ranging from laboratory experiments, both in vitro and in vivo, to epidemiological studies in patients. This review deals with the various mechanisms, and possible pharmacological interventions for the prevention of cataract. The article also reviews research on potential anticataractous agents, including aldose reductase inhibitors, glutathione boosters, antiglycating agents, vitamins and various drugs from indigenous sources.

Induction of ultraviolet cataracts in vitro: prevention by pyruvate

Ultraviolet (UV) radiation is one of the important cataract risk factors. The present studies examined the hypothesis that this effect is due to the UV penetration through the cornea and subsequent induction of a photochemical generation of reactive species of oxygen (ROS) in the aqueous and lens. The hypothesis was ascertained by rat lens organ culture studies conducted under UV (365 nm), with media containing micromolar levels of riboflavin, with and without pyruvate, the latter acting as an ROS scavenger. The implication of ROS in the UV-induced damage was confirmed by measurements of peroxide generation. Damage to the lens was assessed physiologically by measuring the decrease in its active transport of rubidium ions. Biochemically, it was assessed by measuring the lowering of adenosine triphosphate and glutathione. The incorporation of pyruvate in the medium protected the lens against these deleterious effects. That the beneficial effect of pyruvate is attributable to its ROS-scavenging property was proven by the peroxide depletion in its presence, commensurate with its own utilization in parallel. A protective effect of this keto acid against UV-induced tissue damage has been shown for the first time, suggesting its clinical usefulness against UV irradiation-induced pathologies. Hence, further studies on the possible protective effects of such alpha-keto acids against UV damage are in progress.

Susceptibility of the ocular lens to nitric oxide: implications in cataractogenesis

Oxides of nitrogen, such as nitric oxide (NO), are now biologically referred to as reactive nitrogen species. The generation of NO gives rise to several other reactive species, such as NO+, NO-, NO2, N2O3, and ONOO- and so forth, which are all capable of inflicting tissue damage. Indeed, NO generation is known to be associated with retinal degeneration and glaucoma. Its level has also been found to increase in the aqueous and vitreous humors in diabetes. We hypothesize that such an increase would have a detrimental effect on the biochemistry and metabolism of tissues, including the lens, bathed by the aqueous containing elevated levels of NO. The primary aim of our investigations was, therefore, to examine the susceptibility of the lens to damage by NO in vitro in the presence of nitroaspirin, a novel NO donating agent. The extent of physiologic damage to the lens was initially assessed by determining the integrity of its active transport mechanism. The overall status of tissue metabolism was determined by measuring the adenosine triphosphate (ATP) levels. The levels of glutathione (GSH) and glutathione disulfide, reflecting the status of its antioxidant reserve, were also determined. That NO is indeed deleterious to the lens was apparent by the inhibition of the active transport of Rb(+). This was associated with a substantial decrease in the contents of ATP and GSH, the decrease in the latter directly suggesting that the NO effects are caused by oxidative stress. That the effects are caused by NO generated from nitroaspirin was proven by a substantial increase in NO level in the medium during incubation of the lenses with nitroaspirin, as compared to the controls. The results, therefore, were highly suggestive of a contribution of the oxides of nitrogen in cataract formation associated with diabetes and other aging diseases.

Lens thiol depletion by peroxynitrite. Protective effect of pyruvate

Pyruvate (PY) is known to be a potent scavenger of H(2)O(2 )by undergoing its peroxidative decarboxylation. While doing so, it also inhibits .OH generation, in addition to its direct .OH scavenging effect. We now hypothesize that PY would also be decarboxylated by cleaving the -O-O- bond in peroxynitrite (ONOO(-)) (PN), with the effect of protecting tissues against NO(x )induced damage. We have verified this by measuring (14)CO(2) formation on incubation of 1-(14)C-PY with 3-morpholinosydnonimine (SIN-1). Its protective effect against PN induced thiol depletion was initially assessed by determining its ability to inhibit oxidation of pure GSH. This was further evaluated by incubating lens homogenate with SIN-1 with or without PY. As conceived, PY did inhibit PN induced loss of protein as well as non-protein -SH. The findings therefore appear potentially useful to protect against nitrite induced damage to the lens and other tissues known to occur with aging and certain diseases such as diabetes.

Influence of glutathione fructosylation on its properties

Incubation of fructose and glutathione leads to the formation of N-2-deoxy-glucos-2-yl glutathione as the major glycation product, with characteristic positive ion at 470 Th in LC-MS spectra. Glutathione disulfide and fructose generate two compounds: N-2-deoxy-glucos-2-yl glutathione disulfide (m/z=775 Th) and bis di-N,N'-2-deoxy-glucos-2-yl glutathione disulfide (m/z=937 Th). N-2-deoxy-glucos-2-yl glutathione is 2.5-fold less effective than glutathione in reducing dehydroascorbic acid. Glutathione peroxidase and glutahione-S-transferase exhibit marginal activity toward N-2-deoxy-glucos-2-yl glutathione, while glyoxalase I shows 44.9% of the enzyme's specific activity. Glutathione reductase demonstrates 6.9% of the enzyme's specific activity with bis di-N,N'-2-deoxy-glucos-2-yl glutathione, while with mono-N-glucosyl glutathione disulfide retained 5 6.1% of the original activity. Glutathione reductase could not reduce N-2-deoxy-glucos-2-yl glutathione in mixed disulfide with gammaS-crystallin, but reduced glutathione in mixed disulfide with gammaS-crystallin by 90%. The presence of N-2-deoxy-glucos-2-yl glutathione in mixed disulfide with gammaS-crystallin makes this molecule more susceptible to unfolding than native gammaS-crystallin.

Oxidative damage to lens in culture: reversibility by pyruvate and ethyl pyruvate

It is generally believed that prophylactic intake of antioxidants is beneficial in delaying the onset of some aging manifestations such as cataract. However, whether such a supplementation will also be effective if the pathophysiological process has already set in remains a largely open question. We examined this possibility with lens changes leading to cataract formation, since cataract genesis is intimately related to a continued generation of reactive oxygen species (ROS) in the aqueous humor. Since the formation of cataract is a well-defined progressive disease, starting with an early refractive change and leading to gradual enhancement of opacification, we hypothesized that even a belated start with an appropriate anti-oxidant could halt the pathological process and delay cataract maturation and vision impairment. Using lens cultures, we tested this hypothesis with pyruvate, known to be an effective and highly potent ROS scavenger. Adding pyruvate to the culture medium after lenses had sustained a 50% damage was significantly effective in preventing progress. This was apparent by better maintenance of the active rubidium transport activity in these lenses compared to controls without pyruvate treatment. Glutathione levels were also higher in the pyruvate group.

Attenuation and delay of diabetic cataracts by antioxidants: effectiveness of pyruvate after onset of cataract

Cataract is one of the most significant vision-impairing complications of diabetes. The present study examined the feasibility of inhibiting cataract formation by treatment with pyruvate, a metabolite known to effectively scavenge reactive species of oxygen and inhibit protein glycation, both known to be involved in the genesis of diabetic cataracts. In addition, pyruvate stimulates tissue metabolism, which is depressed with the onset of cataract formation. The objective of our experiments was to determine if this compound could be effective in offsetting the progress of cataract, specifically if administered after the diabetes-induced lens changes have begun, as opposed to the previous reports wherein it has been reported to delay cataract formation if administered prophylactically with the immediate onset of diabetes. Diabetes was induced by intraperitoneal administration of streptozotocin to mice. Lens transparency was assessed by slit lamp examination and its photography. ATP was determined enzymatically by reacting it with luciferin-luciferase mixture and measuring the fluorescence intensity. The findings described herein are in accordance with this possibility. The incidence of cataract in the group of diabetic animals, where treatment with pyruvate was initiated after the initial lens changes set in, was significantly lower at all times of observation in comparison to the untreated diabetic group. In addition, the severity of opacities in the pyruvate-treated group, when present, was much minor, the transparency of these cases being close to that in the control animals. The ophthalmic findings are supported biochemically by ATP levels, which were significantly higher in the pyruvate group in comparison to the untreated group. The present findings emphasize the clinical usefulness of initiating treatment with anti-oxidants and metabolic agonists even when the lens changes are detected at the time of the diabetes diagnosis. The latter usually comes much later than the onset of visual aberrations. Prophylaxis is not an absolute requirement.