Pharmacological prevention of diabetic cataract

Dichloroacetate ameliorates apoptosis, EMT and oxidative stress in diabetic cataract via inhibiting the IDO1-dependent p38 MAPK pathway

As an oral antidiabetic agent, dichloroacetate (DCA) has been proven to improve diabetes and related complications. However, its functional role in diabetic cataract (DC) remains to be elucidated. This study was to define the role of DCA and its underlying molecular mechanism in DC in vitro and in vivo. In this study, it was shown that DCA dose-dependently ameliorated DC formation and development in DM rats. In addition, DCA significantly increased cell viability, reduced apoptosis, and inhibited EMT and oxidative stress of high glucose (HG)-treated SRA-01/04 cells in a concentration-dependent manner. Besides, it was revealed that Indoleamine 2,3-dioxygenase 1 (IDO1) expression was upregulated in lenses of DM rats and HG-treated SRA-01/04 cells, which was reversed by DCA. In addition, DCA abrogated the activation of the p38 MAPK signaling in the lenses of DM rats and HG-treated SRA-01/04 cells. Further experiments showed that IDO1 upregulation activated the p38 MAPK signaling in HG-challenged SRA-01/04 cells. Moreover, IDO1 overexpression partially reversed DCA-mediated inactivation of p38 MAPK signaling and suppression of HG-induced damage to SRA-01/04 cells. To sum up, our findings showed that DCA prevented DC-related apoptosis, EMT, and oxidative stress via inactivating IDO1-dependent p38 MAPK signaling.

A bibliometric and visualized analysis of the pathogenesis of cataracts from 1999 to 2023

Research on the pathogenesis of cataracts is ongoing and the number of publications on this topic is increasing annually. This study offers an overview of the research status, popular topics, and scholarly tendencies in the field of cataract pathogenesis over recent decades，which helps to guide future research directions, and optimize resource allocation. In the present study, we performed a bibliometric analysis of cataract pathogenesis. Publications from January 1, 1999, to December 20, 2023, were collected from the Web of Science Core Collection (WoSCC), and the extracted data were quantified and analyzed. We analyzed and presented the data using Microsoft Excel, VOSviewer, CiteSpace, and Python. In all, 4006 articles were evaluated based on various characteristics, including publication year, authors, countries, institutions, journals, citations, and keywords. This study utilized VOSviewer to conduct visualized analysis, including co-authorship, co-citation, co-occurrence, and network visualization. The CiteSpace software was used to identify keywords with significant bursts of activity. The number of annual global publications climbed from 76 to 277 between 1999 and 2023, a 264.47% rise. Experimental Eye Research published the most manuscripts (178 publications), whereas Investigative Ophthalmology & Visual Science received the most citations (6675 citations). The most influential and productive country, institution, and author were the United States (1244 publications, 54,456 citations), University of California system (136 publications, 5401 citations), and Yao Ke (49 publications, 838 citations), respectively. The top 100 ranked keywords are divided into four clusters through co-occurrence analysis: (1) secondary cataracts, (2) oxidative stress, (3) gene mutations and protein abnormalities, and (4) alteration of biological processes in lens epithelial cells. Further discussions on the four subtopics outline the research topics and trends. In conclusion, the specific mechanism of cataract formation remains a popular topic for future research and should be explored in greater depth.

HIF-1 inhibition reverses opacity in a rat model of galactose-induced cataract

Cataract is an eye disease, in which the lens becomes opaque, causing vision loss and blindness. The detailed mechanism of cataract development has not been characterized, and effective drug therapies remain unavailable. Here, we investigated the effects of Hypoxia-inducible factor 1 (HIF-1) inhibitors using an ex vivo model, in which rat lenses were cultured in galactose-containing medium to induce opacity formation. We found that treatment with the HIF-1 inhibitors 2-Methoxyestradiol (2ME2), YC-1, and Bavachinin decreased lens opacity. Microarray analysis on 2ME2-treated samples, in which opacity was decreased, identified genes upregulated by galactose and downregulated by inhibitor treatment. Subsequent STRING analysis on genes that showed expression change by RT-qPCR identified two clusters. First cluster related to the cytoskeleton and epithelial-mesenchymal transition (EMT). Second cluster related to the oxidative stress, and apoptosis. ACTA2, a known marker for EMT, and TXNIP, a suppressor of cell proliferation and activator of apoptosis, were present in each cluster. Thus, suppression of EMT and apoptosis, as well as activation of cell proliferation, appear to underlie the decrease in lens opacity.

Glutamate is effective in decreasing opacity formed in galactose-induced cataract model

Although cataract is the leading cause of blindness worldwide, the detailed pathogenesis of cataract remains unclear, and clinically useful drug treatments are still lacking. In this study, we examined the effects of glutamate using an ex vivo model in which rat lens is cultured in a galactose-containing medium to induce opacity formation. After inducing lens opacity formation in galactose medium, glutamate was added, and the opacity decreased when the culture was continued. Next, microarray analysis was performed using samples in which the opacity was reduced by glutamate, and genes whose expression increased with galactose culture and decreased with the addition of glutamate were extracted. Subsequently, STRING analysis was performed on a group of genes that showed variation as a result of quantitative measurement of gene expression by RT-qPCR. The results suggest that apoptosis, oxidative stress, endoplasmic reticulum (ER) stress, cell proliferation, epithelial-mesenchymal transition (EMT), cytoskeleton, and histones are involved in the formation and reduction of opacity. Therefore, glutamate may reduce opacity by inhibiting oxidative stress and its downstream functions, and by regulating the cytoskeleton and cell proliferation.

Safety and Efficacy of Dexamethasone Intravitreal Implant Given Either First-Line or Second-Line in Diabetic Macular Edema

Diabetic macular edema (DME) is a common sight-threatening complication of diabetic retinopathy (DR) and the leading cause of severe visual impairment among the working-age population. Several therapeutic options are available for the management of DME, including intravitreal corticosteroids. They have been traditionally used as second-line treatment, due to the risk of intraocular pressure increase and cataract-related adverse events. However, attention has recently been focused on the primary or early use of intravitreal corticosteroids, due to growing evidence of the crucial role of inflammation in the pathogenesis of DME. Furthermore, intravitreal steroid implants offer the additional advantage of a longer duration of action compared to anti-vascular endothelial growth factor agents (anti-VEGF). This review aims to summarize the available evidence on the efficacy and safety profile of dexamethasone (DEX) intravitreal implant, with a specific focus on clinical scenarios in which it might be considered or even preferred as first-line treatment option by adequate selection of patients, considering both advantages and possible adverse events. Patients with contraindications to anti-VEGF, DME with high inflammatory OCT biomarkers, pseudophakic patients and phakic patients' candidates to cataract surgery as well as vitrectomized eyes may all benefit from first-line DEX implant. Additionally, DME not responders to anti-VEGF should be considered for a switch to DEX implant and a combination therapy of DEX implant and anti-VEGF could be a valid option in severe and persistent DME.

Changing Trends in the Global Burden of Cataract Over the Past 30 Years: Retrospective Data Analysis of the Global Burden of Disease Study 2019

BACKGROUND

Cataracts now account for the largest proportion of the global burden of blindness and vision loss. Understanding the changing trends in the global burden of cataracts over the past 30 years and the next 15 years is of clear significance for the prevention and control of cataracts in key populations. As far as we know, research on the future burden of cataracts is lacking.

OBJECTIVE

This study aims to assess the global burden of cataracts over the past 30 years by using age-period-cohort modeling and to estimate trends in the next 15 years.

METHODS

Data were obtained from the Global Burden of Disease Study 2019, the United Nations Development Programme, and the WHO (World Health Organization) Global Health Observatory data repository. The assessment of trends and disparities in the number and rate of disability-adjusted life years (DALYs) for cataracts from 1990 to 2019 was conducted. The association between the age-standardized DALY rate (ASDR) and the socio-demographic index (SDI), human development index (HDI), national levels of particulate matter <2.5 μm in diameter (PM2.5), and ambient ultraviolet radiation (UVR) was determined using linear regression analysis. Additionally, we used the Nordpred (Harald Fekjær and Bjørn Møller) age-period-cohort model to predict the cataract burden from 2020 to 2034.

RESULTS

Globally, the number of DALYs due to cataract increased from 3,492,604 (95% uncertainty interval [UI] 2,481,846-4,719,629) in 1990 to 6,676,281 (95% UI 4,761,210-9,006,193) in 2019. The ASDRs due to cataract decreased from 93.17 (95% UI 66.14-125.32) in 1990 to 82.94 (95% UI 59.06-111.75) in 2019, with an average annual percentage change of -0.37 (95% CI -0.44 to -0.3; P<.001). Age, female sex, air pollution, smoking, high fasting plasma glucose levels, and a high body mass index were risk factors for the burden of cataracts. SDI and HDI were negatively correlated with ASDRs of cataracts, while PM2.5 and UVR were positively associated with them. Higher DALY rates were also associated with lower SDI (R2=0.1939; P<.001), lower HDI (R2=0.2828; P<.001), national PM2.5 concentration (R2=0.1874; P<.001), and ambient UVR levels (R2=0.2354; P<.001). The prediction model suggested that the number of DALYs due to cataract will continue to rise globally, while the cataract DALY rate will continue to decrease.

CONCLUSIONS

While the ASDR of cataracts has decreased, there has been a notable increase in the number of DALYs over the past 30 years. Projections suggest that the global burden of cataracts will continue to rise over the next 15 years. To address this challenge, appropriate prevention and treatment policies must be implemented.

Oxidative stress, epigenetic regulation and pathological processes of lens epithelial cells underlying diabetic cataract

Background

Cataract is a blinding disease worldwide. It is an age-related disease that mainly occurs in people over 65 years old. Cataract is also prevalent in patients with diabetes mellites (DM). The pathological mechanisms underlying diabetic cataract (DC) are more complex than that of age-related cataract. Studies have identified that polyol pathway, advanced glycation end products (AGEs) and oxidative stress are the primary pathogenesis of DC. In recent years, molecular-level regulations and pathological processes of lens epithelial cells (LECs) have been confirmed to play roles in the initiation and progression of DC. A comprehensive understanding and elucidation of how chronic hyperglycemia drives molecular-level regulations and cytopathological processes in the lens will shed lights on the prevention, delay and treatment of DC.

Main text

Excessive glucose in the lens enhances polyol pathway and AGEs formation. Polyol pathway causes imbalance in the ratio of NADPH/NADP+ and NADH/NAD+. Decrease in NADPH/NADP+ ratio compromises antioxidant enzymes, while increase in NADH/NAD+ ratio promotes reactive oxygen species (ROS) overproduction in mitochondria, resulting in oxidative stress. Oxidative stress in the lens causes oxidation of DNA, proteins and lipids, leading to abnormalities in their structure and functions. Glycation of proteins by AGEs decreases solubility of proteins. High glucose triggered epigenetic regulations directly or indirectly affect expressions of genes and proteins in LECs. Changes in autophagic activity, increases in fibrosis and apoptosis of LECs destroy the morphological structure and physiological functions of the lens epithelium, disrupting lens homeostasis.

Conclusions

In both diabetic animal models and diabetics, oxidative stress plays crucial roles in the formation of cataract. Epigenetic regulations, include lncRNA, circRNA, microRNA, methylation of RNA and DNA, histone acetylation and pathological processes, include autophagy, fibrosis and apoptosis of LECs also involved in DC.

Butein Inhibits the Glycation of α-Crystallin: An Approach in Prevention of Retinopathy

The aggregation of lens proteins induced by glycation is one of the key drivers of diabetic retinopathy and development of diabetic cataracts. Moreover, glycation also causes numerous alterations not only to the tertiary structure of lens proteins but also to serum proteins. There are also evidences of covalent crosslinking among lens crystallins resulting in development of cataract. In this article, the inhibitory potential of butein was tested against the glucose induced glycation and the aggregation α-crystallin (α-cry). The results showed that there was inhibition of advanced glycation products (78.28%) and early glycation products (86.30%) following the treatment of butein. Additionally, the presence of butein caused a significant improvement in the tested biochemical markers of glycation. The treatment with butein reduced the free lysine modification to 23.67%. The secondary and tertiary structural distortions of α-cry were also protected. The mechanism of inhibition further investigated at the molecular level using biophysical and computational techniques. The interaction data showed the butein exhibited strong affinity towards the α-cry. The binding event was entropically driven and energetically favourable. The Gibb's free energy of the interaction was found to be -5.99 to -7.17 kcal mol^-1. The binding site of butein in α-cry was deciphered by molecular docking and the dynamics was studied using molecular dynamics (MD) simulations. The simulation data showed that butein formed stable complex with α-cry under physiological conditions. Most of the tested parameters from molecular simulations, such as secondary structure, was found to be stable. The data clearly show the potential of butein in inhibiting the glycation induced aggregation of α-cry and hence can be developed as useful inhibitor in the management of diabetic cataract and retinopathy.

Histone acetyltransferase inhibition reverses opacity in rat galactose-induced cataract

Cataract, a disease that causes opacity of the lens, is the leading cause of blindness worldwide. Cataracts secondary to diabetes are common, even in young patients, so they are of significant clinical importance. Here, we used an ex vivo model of galactose-induced cataracts in the rat lens to investigate the therapeutic effects of histone acetyltransferase (HAT) inhibitors. Among the tested HAT inhibitors, TH1834 was the only one that could reverse most of the opacity once it had formed in the lens. Combination treatment with C646/CPTH2 and CBP30/CPTH2 also had therapeutic effects. In lens cross-sections, vacuoles were present in the tissue of the cortical equatorial region of untreated cataract samples. In treated cataract samples, lens tissue regenerated to fill the vacuoles. To identify the genes regulated by HAT inhibitors, qRT-PCR was performed on treated and untreated cataract samples to determine candidate genes. Expression of Acta1 and Stmn4, both of which are involved in the cytoskeleton, were altered significantly in C646+CPTH2 samples. Expression of Emd, a nuclear membrane protein, and Prtfdc1, which is involved in cancer cell proliferation, were altered significantly in CBP30+CPTH2 samples. Acta1, Acta2, Arrdc3, Hebp2, Hist2h2ab, Pmf1, Ppdpf, Rbm3, RGD1561694, Slc16a6, Slfn13, Tagln, Tgfb1i1, and Tuba1c in TH1834 samples were significantly altered. These genes were primarily related to regulation of cell proliferation, the cytoskeleton, and cell differentiation. Expression levels increased with the onset of cataracts and was suppressed in samples treated with HAT inhibitors.

Precise Detection of Cataracts with Specific High-Risk Factors by Layered Binary Co-Ionizers Assisted Aqueous Humor Metabolic Analysis

Diabetes and high myopia as well-known high-risk factors can aggravate cataracts, yet clinical coping strategy remains a bottleneck. Metabolic analysis tends to be powerful for precisely detection and mechanism exploration since most of diseases including cataracts are accompanied by metabolic disorder. Herein, a layered binary co-ionizers assisted aqueous humor metabolic analysis tool is proposed for potentially etiological typing and detection of cataracts, including age-related cataracts (ARC), cataracts with diabetes mellitus (CDM), and cataracts with high myopia (CHM). Startlingly, taking advantage of the optimal machine learning algorithm and all metabolic fingerprints, 100% of accuracy, precision, and recall rates are achieved for arbitrary comparison between groups. Moreover, 11, 9, and 7 key metabolites with explicit identities are confirmed as markers of discriminating CDM from ARC, CHM from ARC, and CDM from CHM, and the corresponding area under the curve values of validation cohorts are 0.985, 1.000, and 1.000. Finally, the critical impact of diabetes/high myopia on cataracts is revealed by excavating the change levels and metabolic pathways of key metabolites. This work updates the insights of prevention and treatment about cataracts at metabolic level and throws out huge surprises and progresses metabolic diagnosis toward a reality.

Evaluation of antioxidative enzymes levels and lipid peroxidation products levels in diabetic and non diabetic senile cataract patients

Background

The current study aimed to investigate the Superoxide dismutase, Glutathione Peroxidase activity, Advanced oxidation Protein products levels, Malondialdehyde levels, Baseline Conjugated Diene concentration, and 8-Isoprostaglandin F2α (8-IPG-F2α) quantification in diabetic and non-diabetic senile cataract patients to find out the pathomechanism of early onset of cataract in diabetic patients.

Methods

This case-control study was performed on 184 subjects undergoing cataract surgery. For 8-IPG-F2α quantification, 35 diabetics and non-diabetic lenses and the entire study included 22 patients with diabetic senile cataracts and non-diabetic senile cataracts of aqueous humor age ≥ 40 years. Ninety-two patients with diabetic senile cataract and non-diabetic senile cataract lenses aged ≥ 40 years were incorporated for all other studies. The student's t-test was used for statistical analysis.

Results

From the study population, the mean age was 63.82 ± 0.6, and 75% of them were female. Higher female prevalence in both groups was observed. The results revealed that the superoxide dismutase and glutathione peroxidase activity were significantly reduced in diabetic patients compared to non-diabetic patients (p < 0.001) in both lenses and aqueous humor. Malondialdehyde, conjugated diene, and 8-IPG-F2α levels significantly increased in diabetic patients when compared to non-diabetic (p < 0.01), and advanced oxidation protein products levels also significantly increased in diabetic patients when compared to non-diabetics in both lenses and aqueous humor (p < 0.001).

Conclusion

The current study revealed that oxidative stress and Lipid per-oxidation have an imperative role in the diabetic-related complication, specifically in the lens, may have a responsibility in the pathomechanism of early onset of cataracts coupled with diabetes mellitus.

Ameliorative effect of pioglitazone on glucose induced glycation of α-crystallin: Management of complications associated with diabetic retinopathy

The glycation and aggregation of lens proteins significantly contribute to the onset of diabetic cataracts as well as the retinopathy. The glycation exerts numerous alterations in the tertiary structural of proteins. Moreover, the covalent crosslinking of lens crystallins also contribute to the cataract formation. In this article, the effect of pioglitazone on glucose induced glycation and aggregation α-crystallin was examined. A remarkable inhibition of early glycation products (~80%) and advanced glycation products (~75%) was recorded by the treatment of pioglitazone. There was >75% recovery in biochemical marker (carbonyl content). The presence of 150 μM of pioglitazone reduced the free lysine modifications to 35%. Treatment of pioglitazone also protected the secondary structural alterations induced by glycation and inhibited the formation of protein aggregates. The interaction studies showed that pioglitazone interacted with α-crystallin via moderate binding affinity. The interaction between pioglitazone interacted and α-crystallin was energetically and entropically favourable. The complex of pioglitazone with studied protein stable in which RMSF, R_g, SASA, RMSD, and the secondary structural components was not affected. The findings show antiglycation activity of pioglitazone along with its mechanism of action highlighting the ability of drug to be possibly developed novel as glycation inhibitor.

Biochemistry of Eye Lens in the Norm and in Cataractogenesis

The absence of cellular organelles in fiber cells and very high cytoplasmic protein concentration (up to 900 mg/ml) minimize light scattering in the lens and ensure its transparency. Low oxygen concentration, powerful defense systems (antioxidants, antioxidant enzymes, chaperone-like protein alpha-crystallin, etc.) maintain lens transparency. On the other hand, the ability of crystallins to accumulate age-associated post-translational modifications, which reduce the resistance of lens proteins to oxidative stress, is an important factor contributing to the cataract formation. Here, we suggest a mechanism of cataractogenesis common for the action of different cataractogenic factors, such as age, radiation, ultraviolet light, diabetes, etc. Exposure to these factors leads to the damage and death of lens epithelium, which allows oxygen to penetrate into the lens through the gaps in the epithelial layer and cause oxidative damage to crystallins, resulting in protein denaturation, aggregation, and formation of multilamellar bodies (the main cause of lens opacification). The review discusses various approaches to the inhibition of lens opacification (cataract development), in particular, a combined use of antioxidants and compounds enhancing the chaperone-like properties of alpha-crystallin. We also discuss the paradox of high efficiency of anti-cataract drugs in laboratory settings with the lack of their clinical effect, which might be due to the late use of the drugs at the stage, when the opacification has already formed. A probable solution to this situation will be development of new diagnostic methods that will allow to predict the emergence of cataract long before the manifestation of its clinical signs and to start early preventive treatment.

Crystallins as Important Pathogenic Targets for Accumulation of Structural Damages Resulting in Protein Aggregation and Cataract Development: Introduction to This Special Issue of Biochemistry (Moscow)

This issue of Biochemistry (Moscow) is dedicated to the role of protein misfolding and aggregation in cataract development. In fact, many genetic mutations or chemical and physical deleterious factors can initiate alterations in the macrostructural order and proper folding of eye lens proteins, which in some cases result in the formation of large light-scattering aggregates, affecting the quality of vision and making lens more prone to cataract development. Diabetes mellitus, which is associated with oxidative stress and mass production of highly reactive compounds, can accelerate unfolding and aggregation of eye lens proteins. This journal issue contains reviews and research articles that describe the destructive effects of mutations and highly reactive metabolites on the structure and function of lens crystallin proteins, as well important molecules in the lens's natural defense system involved in protection against deleterious effects of the physical and chemical factors.

Aqueous extract prepared from steamed red amaranth (Amaranthus gangeticus L.) leaves protected human lens cells against high glucose induced glycative and oxidative stress

HLE-B3 cell line, a human lens epithelial cell line, was used to examine the anti-glycative and anti-oxidative protection of aqueous extract prepared from steamed red amaranth leaves against high glucose induced injury. Phytochemical profile of this aqueous extract was analyzed. HLE-B3 cells were pretreated by this aqueous extract at 0.25%, 0.5%, or 1%, and followed by high glucose treatment. Results showed that the content of phenolic acids, flavonoids, anthocyanins, carotenoids, and triterpenoids in this aqueous extract was in the range of 1,107-2,861 mg/100 g dry weight. High glucose decreased cells viability and suppressed Bcl-2 mRNA expression. This aqueous extract pretreatments raised 11-42% cell survival and upregulated 20-47% Bcl-2 mRNA expression. High glucose reduced Na⁺ -K⁺ ATPase activity and mitochondrial membrane potential (MMP). This aqueous extract raised 27-40% Na⁺ -K⁺ ATPase activity, and 18-51% MMP. High glucose stimulated the generation of total advanced glycative endproducts (AGEs), methylglyoxal, and reactive oxygen species (ROS). This aqueous extract pretreatments lowered total AGEs, methylglyoxal, and ROS levels in the range of 0.38-1.17 folds, 1.7-4.9 nmol/mg protein, and 0.35-1.06 relative fluorescence unit/mg protein. High glucose upregulated mRNA expression of aldose reductase, nuclear factor kappa B, and p38. This aqueous extract pretreatments decreased mRNA expression of these factors in the range of 75-159%, 57-151%, and 54-166%. High glucose downregulated mRNA expression of nuclear factor E2-related factor 2 (Nrf2). This aqueous extract pretreatments increased 12-38% Nrf2 mRNA expression. These results suggested that this aqueous extract might be a potent nutritional supplement to prevent diabetic retinopathy.

Fundamentals of Diabetic Cataractogenesis and Promising Ways of its Pharmacological Correction

Cataracts in diabetes mellitus lead to decreased visual function and blindness. Cataract surgery for diabetes mellitus has limitations and complications. The search for effective means of conservative cataract therapy continues. The review presents the analysis of data from scientific sources, mainly for 2015–2020 using Internet resources (PubMed, Web of Science, Medline, eLibrary.Ru, Cyberleninka). In the work, diabetic cataractogenesis is presented as a sum of interrelated pathobiochemical processes. The main ones are the polyol pathway of glucose conversion, non-enzymatic glycation and oxidative modification of lens proteins, which are enhanced in diabetes mellitus. The lens has a high protein content. The formation of high molecular weight protein aggregates is of particular importance for the appearance of light scattering zones and a decrease in lens transparency. This review presents data on anti-cataract compounds that affect post-translational crystallin modification, prevent osmotic and oxidative stress in the lens, and exhibit antiglycation properties. This information shows that the search for means of pharmacological correction of cataractogenesis should be carried out among compounds with antioxidant and antiglycation activity. 

Effects of Binahong (Anredera cordifolia (Tenore) Steenis) Extracts on the Levels of Malondialdehyde (MDA) in Cataract Goat Lenses

Cataracts are one of the most causes of blindness in the world. Oxidative stress can form pathological conditions such as cataracts. This oxidative stress ability can be measured by the malondialdehyde (MDA) biomarker. Binahong leaves (Anredera cordifolia (Tenore) Steenis) are native plants from Indonesia that are used to treat various diseases including cataract treatment. Binahong leaf (Anredera cordifolia (Tenore) Steenis) has a high amount of flavonoids and is rich in antioxidants that can be used to treat cataracts. Objective. The purpose of this study was to assess the effect of binahong leaf extract on the levels of MDA in a goat lens with cataract-induced material. Method. As many as possible, 40 goat eye lenses were divided into several groups, namely, group I normal lenses as controls (glucose 5.5 mM), group II lenses were cataract induced with glucose concentration of 55 mM, group III lenses with glucose 55 mM + binahong leaf extract (100 μg/ml), group IV lens with glucose 55 mM + binahong leaf extract (200 μg/ml), and group V lens with glucose 55 mM + quercetin (positive control). Biochemical parameters measured in the lens homogenate are malondialdehyde lens morphology in all groups' observations and comparisons made. Results. The results of the study found that the lens group with the addition of binahong extract showed more results transparency compared to lens groups induced by glucose concentrations of 55 mM). This shows that the diabetic cataract group experienced high oxidative stress due to the accumulation of sorbitol compounds derived from glucose which caused turbidity in the goat eye lens and increased levels of lens MDA. Binahong levels at concentrations of 100 or 200 can inhibit MDA production. Conclusion. Binahong (Anredera cordifolia (Tenore) Steenis) extract has the ability to inhibit the production of MDA levels. In glucose-induced goat lenses, binahong extract and quercetin show antioxidant and anticataract properties.

Novel substituted N-benzyl(oxotriazinoindole) inhibitors of aldose reductase exploiting ALR2 unoccupied interactive pocket

Recently we have developed novel oxotriazinoindole inhibitors (OTIs) of aldose reductase (ALR2), characterized by high efficacy and selectivity. Herein we describe novel OTI derivatives design of which is based on implementation of additional intermolecular interactions within an unoccupied pocket of the ALR2 enzyme. Four novel derivatives, OTI-(7-10), of the previously developed N-benzyl(oxotriazinoindole) inhibitor OTI-6 were synthetized and screened. All of them revealed 2 to 6 times higher ALR2 inhibitory efficacy when compared to their non-substituted lead compound OTI-6. Moreover, the most efficient ALR2 inhibitor OTI-7 (IC₅₀ = 76 nM) possesses remarkably high inhibition selectivity (S_F ≥ 1300) in relation to structurally related aldehyde reductase (ALR1). Derivatives OTI-(8-10) bearing the substituents -CONH₂, -COOH and -CH₂OH, possess 2-3 times lower inhibitory efficacy compared to OTI-7, but better than the reference inhibitor OTI-6. Desolvation penalty is suggested as a possible factor responsible for the drop in ALR2 inhibitory efficacy observed for derivatives OTI-(8-10) in comparison to OTI-7.

Immunoreactivity of ICAM-1, MMP-2, and Nesfatin-1 in lens epithelial cells of patients with diabetes mellitus with or without diabetic retinopathy

PURPOSE

The aim of this study was to evaluate the immunoreactivity of matrix metalloproteinases-2 (MMP-2), intercellular adhesion molecule-1 (ICAM-1), and nesfatin-1 in cataract lens epithelial cells (LECs) of patients with diabetes mellitus (DM) and to investigate the relationship of these markers with DM cataract and diabetic retinopathy (DR).

MATERIALS AND METHODS

Ninety patients were included in the study. The patients were divided into three groups (n = 30): Group 1 (control; patients without DM or DR); Group 2 (patients with DM only), and Group 3 (patients with both DM and DR). Lens capsule samples were collected during intraoperative cataract surgery. Samples were immunohistochemically stained for MMP-2, ICAM-1, and nesfatin-1 and their immunoreactivity was evaluated. The number of immunoreactive cells was determined with a microscope at ×400 magnification.

RESULTS

Increased MMP-2 and ICAM-1 immunoreactivity was detected in the LECs of patients with DM, and especially in patients with DR (p < 0.001, p < 0.001, respectively). Nesfatin-1 immunoreactivity was significantly lower in LECs of diabetic patients (p < 0.001). The mean of MMP-2 immunoreactive cells were 7.47 ± 8.18, 22.80 ± 15.70, and 34.80 ± 20.85 in Groups 1, 2, and 3, respectively. The mean of ICAM-1 immunoreactive cells were 17.10 ± 9.83, 38.50 ± 23.55, and 56.93 ± 20.94 in Groups 1, 2, and 3, respectively.

CONCLUSION

Nesfatin-1, MMP-2, and ICAM-1 and could potentially play important roles in the pathogenesis of cataracts in patients with DM.

Expression of α-Klotho Is Downregulated and Associated with Oxidative Stress in the Lens in Streptozotocin-induced Diabetic Rats

Purpose: Oxidative stress, an imbalance between the production of reactive oxygen species and antioxidant defenses, plays an important role in the pathogenesis of diabetic cataract. The lens in diabetes mellitus (DM) has been shown to exhibit impaired antioxidant defenses, but the underlying mechanisms remain poorly understood. Accumulating evidence reveals that Klotho family genes can regulate antioxidant defenses and prevent oxidative stress in multiple tissues. Here, we examined whether DM alters Klotho expression in the lens and if so, whether altered Klotho expression is associated with oxidative stress in the lens in DM.

Methods: Male Wistar rats were divided into DM and control groups. DM was induced by injection of streptozotocin (STZ, 60 mg/kg ip) and control rats were injected with vehicle. Twelve weeks after DM induction, levels of α-Klotho in plasma, expression of α- and γ-Klotho, and nuclear factor erythroid 2-related factor 2 (Nrf2), and levels of antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione (GSH) and oxidative stress marker malondialdehyde (MDA) in the lens were measured.

Results: Diabetic rats had markedly higher blood glucose concentrations and lower plasma α-Klotho levels than control rats. Both α- and γ-Klotho were expressed in the lens in diabetic and control rats. The expression of α-Klotho but not γ-Klotho in the lens was downregulated in diabetic rats, which was accompanied by reduced expression of nuclear Nrf2 and levels of all antioxidants and increased levels of MDA. Moreover, expression of α-Klotho in the lens was positively correlated with expression of nuclear Nrf2 and levels of all antioxidants, but negatively correlated with levels of MDA.

Conclusions: These findings suggest that DM selectively reduces α-Klotho levels in the circulation and lens, which may attenuate transcriptional activity of Nrf2 and impair antioxidant defenses in response to oxidative insults, contributing to oxidative stress and cataract formation in DM.

Update on the Effects of Antioxidants on Diabetic Retinopathy: In Vitro Experiments, Animal Studies and Clinical Trials

Current therapies for diabetic retinopathy (DR) incorporate blood glucose and blood pressure control, vitrectomy, photocoagulation, and intravitreal injections of anti-vascular endothelial growth factors or corticosteroids. Nonetheless, these techniques have not been demonstrated to completely stop the evolution of this disorder. The pathophysiology of DR is not fully known, but there is more and more evidence indicating that oxidative stress is an important mechanism in the progression of DR. In this sense, antioxidants have been suggested as a possible therapy to reduce the complications of DR. In this review we aim to assemble updated information in relation to in vitro experiments, animal studies and clinical trials dealing with the effect of the antioxidants on DR.

Antidiabetic and aldose reductase inhibitory potentials ofLand caltropsaqueous extract in streptozotocin-nicotinamide induced diabetic rats

Introduction:Diabetic retinopathy is a late stage complication in diabetic patients and one which dramatically affects quality of life. Persistent hyperglycemia results in sorbitol accumulation due to increased activity of aldose reductase (AR), which leads to changes in membrane permeability and leakage of glutathione (GSH) from the lens which in turn results in the development of cataract and retinopathy. Hence, the present study was designed to assess the effect ofTribulus terrestrison AR activity and GSH level in diabetic rat lens, random blood glucose, hemoglobin A1c (HbA1c) and insulin.Methods:Diabetes mellitus was induced by intra-peritoneal (i.p) injection of streptozotocinnicotinamide (STZ-NA). Animals were divided into 5 groups including normal controls (NC) treated with saline, untreated diabetic controls (DC),T. terrestris(150 and 300 mg/kg) and glibenclamide (500 µg/kg) treated diabetic rats. After 16 weeks of treatment, the rats were sacrificed, the lens was removed through posterior approach and homogenate was prepared for AR activity estimation. The lens tissue homogenate was prepared in normal saline for the estimation of GSH. Blood glucose was estimated by glucometer, HbA1c by nephelometry and insulin by ELISA kit.Results:AR activity was significantly reduced (P<0.004) inT. terrestris(both doses) treated groups compared to untreated diabetic controls. GSH levels were found significantly higher (P<0.005) in treated groups than the ones in diabetic controls. Glucose, HbA1c and insulin were significantly improved (P<0.004) in plant extract treated groups when compared to untreated diabetic rats.Conclusion:Tribulus terrestrisaqueous extract may be useful as AR inhibitor. It also has antioxidant and antidiabetic activities and thereby might be capable of controlling the hyperglycemia induced tissue damage.

The effect of the glycemic control on the aqueous humor glucose levels in diabetic patients undergoing elective cataract surgery

PURPOSE

Aqueous humor glucose levels play a role in the anterior segment disorders' pathophysiology, mainly in diabetics. Our purpose was to evaluate the ratio of aqueous humor glucose levels to blood glucose levels in diabetics and to evaluate the correlation between this ratio and blood glycated hemoglobin (HbA1c) levels.

METHODS

This prospective study was performed in Sheba Medical Center during 2016-2018. The study included type 2 diabetic patients admitted for elective cataract surgery. Blood glucose levels were measured immediately before surgery. HbA1c was obtained within 3 months preoperatively. At the beginning of surgery, 0.05-0.1 mL aqueous humor was drawn. Main outcome measures were aqueous humor glucose/blood glucose ratio and the correlation between HbA1c and aqueous humor glucose/blood glucose ratio.

RESULTS

Thirty-seven patients (mean age 75.2 ± 11.2 years) were recruited. The average aqueous humor glucose/blood glucose ratio was 0.69 ± 0.20. A significant positive correlation was found between aqueous humor and blood glucose levels, Pearson coefficient constant R = 0.63 (p < 0.01), and specifically stronger among older patients R = 0.89 (p < 0.01), females R = 0.74 (p < 0.01), patients with short-term disease (<10 years) R = 0.80 (p < 0.01), and patients treated with oral anti-diabetic treatment R = 0.74 (p < 0.01). A significant strong positive correlation was found between HbA1c levels and aqueous humor glucose/blood glucose ratio R = 0.62 (p < 0.01), and specifically stronger among older patients R = 0.82 (p < 0.01), males R = 0.70 (p < 0.01), patients with prolonged disease (⩾10 years) R = 0.540 (p < 0.05), and patients treated with oral anti-diabetic treatment R = 0.62 (p < 0.01).

CONCLUSION

A significant strong correlation was found between aqueous humor glucose levels and blood glucose levels. Poor glycemic control was strongly correlated with an increased ratio, reflecting an increased anterior chamber's glucose permeability. Older age group was found to have stronger correlation of poor glycemic control with this ratio.

Anticataract effects of S. cumini and A. marmelos on goat lenses in an experimental diabetic cataract model

Background

Cataractogenesis in diabetes mellitus is mainly due to generation of free radicals causing oxidative stress. Antioxidants are known to delay cataractogenesis. Indigenous plants are potential promising sources of antioxidants.

Objectives

The present study was done in goat lenses for exploring local antioxidant and anticataract potential of Syzygium cumini (Jamun) and Aegle marmelos (Bael) and comparing their activities.

Material and methods

“Lens organ culture technique” was employed using “tissue culture medium 199” (TC 199). Lenses were divided into four groups of 30 each. Group 1 was “Normal Control”. In remaining 3 groups, experimental diabetic cataract was produced using dextrose (110 mM). Group 2: “Toxic Control” (untreated experimental diabetic cataract lenses). Group 3: S. cumini seed extract (0.25%) treated lenses. Group 4: A. marmelos leaf extract (0.25%) treated lenses. Biochemical parameters measured in lens homogenates included total soluble lens proteins (index of cataractogenesis), malondialdehyde (index of lipid peroxidation), and superoxide dismutase, glutathione reductase, and glutathione peroxidase (indices of antioxidant enzyme activity). Lens morphology was compared in all groups.

Results

S. cumini and A. marmelos showed significantly increased activity of all three antioxidant enzymes, preserved total soluble proteins and decreased malondialdehyde (MDA). Lens morphology was well preserved with these extracts. S. cumini aqueous seed extract scored better over A. marmelos.

Conclusion

In goat lenses with dextrose-induced experimental diabetic cataract, S. cumini and A. marmelos showed antioxidant and anticataract properties and preservation of lens morphology (p < 0.0001 to 0.05). S. cumini showed better anticataract activity than A. marmelos.

Chrysin Reduces Oxidative Stress but Does Not Affect Polyol Pathway in the Lenses of Type 1 Diabetic Rats

Prolonged hyperglycemia is one of the main causes of reactive oxygen species and free radicals generation in diabetes which may affect various organs, including the eye. Oxidative damage to proteins and lipids in the eye lens could lead to cataract formation. To cope with oxidative stress, the endogenous antioxidative system may be supported by the supplementation of exogenous antioxidants. The aim of this study was to evaluate the effect of chrysin, a natural flavonoid, on oxidative stress and polyol pathway-related markers in the lenses of streptozotocin-induced type 1 male diabetic rats. Chrysin at doses of 50 and 100 mg/kg was administered by gavage for 28 days. This treatment resulted in a decrease in antioxidative enzymes activity and oxidative stress index. Moreover, chrysin administration elevated the reduced glutathione level in the lenses. A decrease in the markers linked to oxidative damage to proteins and lipids in the lenses was noted, especially after treatment with 50 mg/kg of chrysin. Neither of the chrysin doses affected glycemia-related markers in the serum or altered parameters related to the polyol pathway and advanced glycation end-products level in the lenses of diabetic rats. Upon obtaining results, it can be concluded that chrysin reveals antioxidative activity in the lenses but shows no antihyperglycemic or antiglycation properties.

Efficacy of melatonin in restoring the antioxidant status in the lens of diabetic rats induced by streptozotocin

Background

Melatonin is a well-known free radical scavenger. The present study aimed to investigate the effects of melatonin treatment on the antioxidant status in the lenticular tissue of streptozotocin (STZ)-induced diabetic rats.

Methods

Thirty-four male rats were randomly divided into four groups as follows: healthy control rats (group 1, n = 10); diabetic control rats (group 2, n = 10); melatonin-treated (5 mg/kg·day) diabetic rats (group 3, n = 10) and melatonin-treated (5 mg/kg·day) healthy rats (group 4, n = 4). Diabetes was induced by injection of streptozotocin (50 mg/kg, ip). Following 8-weeks of melatonin treatment, all rats were killed and the blood plasma and their lenses were stored at -70 °C for antioxidant enzyme activities assay and biochemical determination.

Results

The plasma glucose and lens malondialdehyde (MDA) increased significantly in the rats of group 2 as compared to the group 1. Also, a significant decrease in the levels of catalase (CAT) and glutathione reductase (GR) activities in the lenses and plasma reduced glutathione (GSH) was found. However, the levels of lenticular MDA (not significant) and the plasma glucose significantly decreased in the rats of group 3 compared to the group 2. Besides, the levels of CAT, GR in the rats lens and plasma GSH increased significantly.

Conclusion

Diabetes mellitus induced hyperglycemia and oxidative stress, whereas melatonin decreased the blood glucose levels and lipid peroxidation and increased the activities of antioxidant enzymes in diabetic rat lenses.

Prevention of α-crystallin glycation and aggregation using l-lysine results in the inhibition of in vitro catalase heat-induced-aggregation and suppression of cataract formation in the diabetic rat

The principle role of α-crystallin is chaperoning activity that protect s other proteins against different stresses. High glucose concentration induces the osmotic stress and results in biomacromolecules glycation, which is subsequently cause their conformational and functional changes. Here, the roles of l-lysine (Lys) on the prevention of α-crystallin glycation in both in vitro and in vivo conditions are investigated. The catalase (CAT) activity was considered as a marker of α-crystallin functionality in both conditions. Streptozotocin-induced diabetic rats were treated with 0.1% of the Lys in drinking water. The purified α-crystallin was also incubated with glucose, in the presence or absence of the Lys and its structure-function was compared. The results showed that the visual cataract score was significantly lower in the diabetic rats treated with Lys. After Lys treatment, CAT, superoxide dismutase, aldose reductase and other biochemical parameters in the lens and serum of the diabetic rats returned to the normal value. Formation of the advanced glycation endproducts (AGEs), protein cross-linking, and the hydrophobicity of α-crystallin were changed due to glycation, but they were reversed by Lys treatment. The glycated α-crystallin lost its chaperone activity against heat denatured-CAT, but in the presence of Lys, it preserved its activity and prevented CAT aggregation. In conclusion, Lys treatment significantly inhibited the progression of diabetic cataract in rats. These effects were due to the Lys antiglycating and antioxidant effects, in addition to its protective effect against α-crystallin chaperoning activity.

Zinc Supplementation Ameliorates Diabetic Cataract Through Modulation of Crystallin Proteins and Polyol Pathway in Experimental Rats

Non-enzymatic glycation of lens proteins and elevated polyol pathway in the eye lens have been the characteristic features of a diabetic condition. We have previously reported the benefits of zinc supplementation in reducing hyperglycemia and associated metabolic abnormalities and oxidative stress in diabetic rats. The current study explored whether zinc supplementation protects against cataractogenesis through modulation of glycation of lens proteins, elevated polyol pathway, oxidative stress, and proportion of different heat shock proteins in the eye lens of diabetic rats. Streptozotocin-induced diabetic rats were fed with a zinc-enriched diet (5 and 10 times of normal) for 6 weeks. Supplemental zinc alleviated the progression and maturation of diabetes-induced cataract. Zinc was also effective in preventing the reduced content of total and imbalanced proportion of soluble proteins in the lens. Supplemental zinc also alleviated cross-linked glycation and concomitant expression of the receptor of glycated products and oxidative stress indicators in the eye lens. Zinc supplementation further induced the concentration of heat shock protein in the eye lens of diabetic rats, specifically α-crystallin. Zinc supplementation counteracted the elevated activity and expression of polyol pathway enzymes and molecules in the lens. The results of this animal study endorsed the advantage of zinc supplementation in exerting the antiglycating influence and downregulating polyol pathway enzymes to defer cataractogenesis in diabetic rats.

Lanosterol Synthase Pathway Alleviates Lens Opacity in Age-Related Cortical Cataract

Purpose

Lanosterol synthase (LSS) abnormity contributes to lens opacity in rats, mice, dogs, and human congenital cataract development. This study examined whether LSS pathway has a role in different subtypes of age-related cataract (ARC).

Methods

A total of 390 patients with ARC and 88 age-matched non-ARC patients were enrolled in this study. LSS expression was analyzed by western blot and enzyme-linked immunosorbent assay (ELISA). To further examine the function of LSS, we used U18666A, an LSS inhibitor in rat lens culture system.

Results

In lens epithelial cells (LECs), LSS expression in LECs increased with opaque degree C II, while it decreased with opaque degree C IV and C V. While in the cortex of age-related cortical cataract (ARCC), LSS expression was negatively related to opaque degree, while lanosterol level was positively correlated to opaque degree. No obvious change in both LSS and lanosterol level was found in either LECs or the cortex of age-related nuclear cataract (ARNC) and age-related posterior subcapsular cataract (ARPSC). In vitro, inhibiting LSS activity induced rat lens opacity and lanosterol effectively delayed the occurrence of lens opacity.

Conclusions

This study indicated that LSS and lanosterol were localized in the lens of human ARC, including ARCC, ARNC, and ARPSC. LSS and lanosterol level are only correlated with opaque degree of ARCC. Furthermore, activated LSS pathway in lens is protective for lens transparency in cortical cataract.

Aldo-Keto Reductases: Multifunctional Proteins as Therapeutic Targets in Diabetes and Inflammatory Disease

Aldose reductase (AR) is an NADPH-dependent aldo-keto reductase that has been shown to be involved in the pathogenesis of several blinding diseases such as uveitis, diabetic retinopathy (DR) and cataract. However, possible mechanisms linking the action of AR to these diseases are not well understood. As DR and cataract are among the leading causes of blindness in the world, there is an urgent need to explore therapeutic strategies to prevent or delay their onset. Studies with AR inhibitors and gene-targeted mice have demonstrated that the action of AR is also linked to cancer onset and progression. In this review we examine possible mechanisms that relate AR to molecular signaling cascades and thus explain why AR inhibition is an effective strategy against colon cancer as well as diseases of the eye such as uveitis, cataract, and retinopathy.

Expression of SIRT1 and P53 in Rat Lens Epithelial cells in Experimentally Induced DM

PURPOSE

To determine the etiopathogenesis of diabetic cataract by studying changes in relative expressions of silent information regulator protein-1 (SIRT1) and P53 in rat lens epithelial cells (LECs) in experimentally induced diabetes mellitus (DM).

METHODS

Six-week-old male SD rats (n = 120) were randomly divided into experimental (n = 80 rats) and control (n = 40 rats) groups. DM was induced in the experimental group (diabetic model) by intraperitoneal (i.p.) injection of 60 mg/kg streptozotocin (STZ). Control group rats were injected similarly with phosphate-buffered saline (PBS). Four and eight weeks after successful induction of DM, relative expressions of SIRT1 and P53 in LECs were analyzed using quantitative real-time (qRT) fluorescence polymerase chain reaction (qRT-PCR) and Western blot analysis.

RESULTS

Expression of both SIRT1 and P53 was observed in LECs of control and experimental group rats at 4 and 8 weeks but was significantly greater in experimental compared with control group rats (p < 0.05).

CONCLUSIONS

Expression of both SIRT1 and P53 increases in the early stages of diabetic cataract formation, indicating that they play potentially important roles in the pathogenesis of diabetic cataract.

Upregulations of Clcn3 and P-Gp Provoked by Lens Osmotic Expansion in Rat Galactosemic Cataract

OBJECTIVE

Lens osmotic expansion, provoked by overactivated aldose reductase (AR), is the most essential event of sugar cataract. Chloride channel 3 (Clcn3) is a volume-sensitive channel, mainly participating in the regulation of cell fundamental volume, and P-glycoprotein (P-gp) acts as its modulator. We aim to study whether P-gp and Clcn3 are involved in lens osmotic expansion of galactosemic cataract.

METHODS AND RESULTS

In vitro, lens epithelial cells (LECs) were primarily cultured in gradient galactose medium (10-60 mM), more and more vacuoles appeared in LEC cytoplasm, and mRNA and protein levels of AR, P-gp, and Clcn3 were synchronously upregulated along with the increase of galactose concentration. In vivo, we focused on the early stage of rat galactosemic cataract, amount of vacuoles arose from equatorial area and scattered to the whole anterior capsule of lenses from the 3rd day to the 9th day, and mRNA and protein levels of P-gp and Clcn3 reached the peak around the 9th or 12th day.

CONCLUSION

Galactosemia caused the osmotic stress in lenses; it also markedly leads to the upregulations of AR, P-gp, and Clcn3 in LECs, together resulting in obvious osmotic expansion in vitro and in vivo.

A novel thiazolidinediones ATZD2 rescues memory deficits in a rat model of type 2 diabetes through antioxidant and antiinflammation

Type 2 diabetes (T2DM) has been associated with learning and memory impairment; however, drugs for diabetes could not prevent the development of cognitive decline in T2DM patients. In the present study, compounds derived from thiazolidinediones (TZD), a PPAR-γ agonist, were synthesized by conjuncting the alkyl-substituted benzimidazole group to TZD group (ATZDs). Based on the in vitro evaluation, the neuroprotection of ATZD2 was further investigated using a streptozotocin-induced T2DM rat model. Pharmacokinetic study showed that ATZD2 could pass the blood-brain barrier (BBB) while the rosiglitazone (RSG, the precursor compound of ATZD2) not. Administration of ATZD2 significantly promoted the survival rate and attenuated fasting blood glucose (FBG) levels as compared to RSG treatment in T2DM rats. Furthermore, ATZD2 treatment ameliorated the impairment of learning and memory by Morris water maze test. The beneficial effects of ATZD2 were associated with the down-regulation of hypoxia induced factor-1α, aldose reductase, and Bax expression which are related to T2DM pathology. ATZD2 treatment also attenuated the expression of inflammatory cytokines and restored the balance of redox in the diabetic hippocampus. These effects were more potent as compared with that of RSG at the same dose. The data indicate that ATZD2 may be a potent agent for the treatment of cognitive dysfunction in T2DM.

Inhibitory Effect of Arachis hypogaea (Peanut) and Its Phenolics against Methylglyoxal-Derived Advanced Glycation End Product Toxicity

Methylglyoxal (MGO) is a highly reactive dicarbonyl compound that causes endothelial dysfunction and plays important roles in the development of diabetic complications. Peanuts are rich in energy, minerals, and antioxidants. Here, we report the potential beneficial effects of peanuts, and particularly the phenolic contents, against MGO-mediated cytotoxicity. Firstly, we optimized the extraction conditions for maximum yield of phenolics from peanuts by examining different processing methods and extraction solvents. To estimate the phenolic contents of peanut extracts, a simultaneous analysis method was developed and validated by ultra-high-performance liquid chromatography-tandem mass spectrometry. We found that roasted peanuts and their 80% methanol extracts showed the highest amount of total phenolics. Secondly, we evaluated the inhibitory effects of phenolics and peanut extracts against MGO-mediated cytotoxicity. Phenolics and peanut extracts were observed to inhibit advanced glycation end product (AGE) formation as well as to break preformed AGEs. Furthermore, pretreatment with peanut extracts significantly inhibited MGO-induced cell death and reactive oxygen species production in human umbilical vein endothelial cells. Peanut extracts prevented MGO-induced apoptosis by increasing Bcl-2 expression and decreasing Bax expression, and MGO-mediated activation of mitogen-activated protein kinases (MAPKs). In conclusion, the constituents of peanuts may prevent endothelial dysfunction and diabetic complications.

Effects of microRNA-211 on proliferation and apoptosis of lens epithelial cells by targeting SIRT1 gene in diabetic cataract mice

Our study aimed at exploring the effects of miR-211 on the proliferation and apoptosis of lens epithelial cells in diabetic cataract mice by targetting NAD⁺-dependent histone deacetylase sirtulin 1 (SIRT1). Healthy male mice were assigned into normal and diabetic cataract groups. Blood glucose, lens turbidity, and apoptosis were measured. Lens epithelial cells were classified into the normal, blank, negative control (NC), miR-211 mimics, miR-211 inhibitors, siRNA-SIRT1, and miR-211 inhibitors + siRNA-SIRT1 groups. MiR-211, Bcl-2, Bax, p53, and SIRT1 expressions of each group were detected. Cell proliferation, cycle and apoptosis were tested by MTT assay and flow cytometry. MiR-211 can specifically bind to SIRT1 according to the luciferase system. SIRT1 protein concentration was strongly positive in normal mice and weakly positive in diabetic cataract mice. Apoptosis index of diabetic cataract mice was higher than the normal mice. Compared with normal mice, the expressions of miR-211, Bax, and p53 increased in diabetic cataract mice, while the Bcl-2 and SIRT1 expressions decreased. In comparison with the blank and NC groups, the expressions of miR-211, Bax, and p53 increased, while Bcl-2 and SIRT1 expressions decreased, and the proliferation decreased and apoptosis rate increased in the miR-211 mimics and siRNA-SIRT1 groups; the results were contradicting for the miR-211 inhibitor group. MiR-211 could promote apoptosis and inhibit proliferation of lens epithelial cells in diabetic cataract mice by targetting SIRT1.

Delaying of cataract through intervention of Hemidesmus indicus in STZ induced diabetic rats

Hemidesmus indicus (L.) R. Br. was extensively used as hypoglycaemic agent and significance of this plant on secondary complications of diabetes remained unknown. The present study was to investigate the anti-cataractous activity of H. indicus against streptozotocin (STZ)-induced diabetic cataract in rodent model. Root extracts have been prepared and tested for inhibition of rat lens aldose reductase (AR) activity. In addition, its pharmacological potential has been investigated in STZ-induced diabetic cataract. Methanol extract of H. indicus-inhibited AR activity in vitro decreased the blood glucose levels, inhibited the AR activity and delayed the onset and progression of cataract in a dose-dependent manner in in vivo and the antioxidant markers have been normalised. Our results demonstrate that H. indicus has decrease the osmotic stress by inhibiting the AR activity and prevented the loss of antioxidants and delayed the progression of diabetic cataract in STZ-induced diabetic rats.

Functional food supplements to ameliorate the secondary complications in high fructose fed diabetic rats

Poly-herbal functional food supplements inhibited high fructose induced glycation in diabetic rats and showed promise for effective management of secondary complications of diabetes such as improved lipid profile, kidney function and reduction of oxidative stress.

Investigation of synergistic mechanism and identification of interaction site of aldose reductase with the combination of gigantol and syringic acid for prevention of diabetic cataract

BACKGROUND

Gigantol and syringic acid (SA) have been shown to synergistically prevent formation of diabetic cataract (DC). However, the exact mechanism of this effect is unknown. Here, we investigate the effect of these compounds on the activity of aldose reductase (AR) and cataract formation.

METHODS

We examined the synergistic anti-cataract efficacy of gigantol and SA in the high glucose- and streptozotocin -induced DC rat model; synergism was evaluated using Jin's formula. We investigated possible mechanisms of action by measuring AR expression and activity and levels of sorbitol using enzyme kinetics, Western blot, and RT-PCR. Finally, we examined binding interaction between AR and both compounds using a combination of site-directed mutagenesis, recombinant expression of wild-type and mutant proteins, and enzyme kinetics.

RESULTS

Combination treatment of gigantol and SA synergistically protected both HLECs(human lens epithelial cells) grown in vitro and DC formation in STZ-induced rats in vivo. Synergism was attributed to inhibition of AR activity, downregulation of AR expression via impaired transcription, and decreased sorbitol levels. Enzyme kinetics studies showed that the activity of an AR Asn160Ala mutant protein was significantly decreased compared to wild-type AR, confirming that Asn160 is a key residue for interaction between AR and both compounds.

CONCLUSION

Combined administration of gigantol and SA synergize to enhance anti-cataract efficacy. The synergistic effect is mainly attributed to disruption of the polyol pathway and inhibition of AR activity.

Protective effect of Tephrosia purpurea in diabetic cataract through aldose reductase inhibitory activity

PURPOSE

Tephrosia purpurea (T. purpurea) has been reported to prevent cataract formation in senile cataract model as well as proven effective in STZ induced type 1 diabetes. Aldose reductase (AR) is a key enzyme in the intracellular polyol pathway responsible for the development of diabetic cataract.

OBJECTIVE

To investigate the effects of T. purpurea in the light of inhibition of aldose reductase enzyme in polyol pathway.

METHODS

We studied the effects of alcoholic extract and flavonoid fraction of T. purpurea in streptozotocin (STZ, 45mg/kg, i.v.)-induced type I diabetic cataract in rats. The animals were divided into five groups as control, control treated with alcoholic and flavonoid fraction, diabetic control and diabetic treated with alcoholic and flavonoid fraction. In-vitro aldose reductase inhibitory activity was also evaluated. Further, molecular docking study was performed with crystal structure of aldose reductase and its known chemical constituents of the plant.

RESULTS

The IC₅₀ value of alcoholic extract for aldose reductase inhibition was found to be 209.13μg/ml, and that of flavonoid fraction was found to be 46.73μg/ml. Administration of STZ produced significantly abnormal levels of serum glucose, serum insulin, soluble protein and antioxidants in the lens homogenate. Treatment with alcoholic extract and flavonoid fraction of T. purpurea were able to normalize these levels. Some of the active constituents of T. purpurea showed significant interactions with aldose reductase enzyme in molecular docking studies.

CONCLUSIONS

Our data suggested that both the extracts might be helpful in delaying the development of diabetic cataract due to the presence of rutin and quercetin. This beneficial effect may be due to its significant inhibition of aldose reductase enzyme and anti-oxidant activity.

Virtual phacoemulsification surgical simulation using visual guidance and performance parameters as a feasible proficiency assessment tool

BACKGROUND

Computer based surgical training is believed to be capable of providing a controlled virtual environment for medical professionals to conduct standardized training or new experimental procedures on virtual human body parts, which are generated and visualised three-dimensionally on a digital display unit. The main objective of this study was to conduct virtual phacoemulsification cataract surgery to compare performance by users with different proficiency on a virtual reality platform equipped with a visual guidance system and a set of performance parameters.

METHODS

Ten experienced ophthalmologists and six medical residents were invited to perform the virtual surgery of the four main phacoemulsification cataract surgery procedures - 1) corneal incision (CI), 2) capsulorhexis (C), 3) phacoemulsification (P), and 4) intraocular lens implantation (IOL). Each participant was required to perform the complete phacoemulsification cataract surgery using the simulator for three consecutive trials (a standardized 30-min session). The performance of the participants during the three trials was supported using a visual guidance system and evaluated by referring to a set of parameters that was implemented in the performance evaluation system of the simulator.

RESULTS

Subjects with greater experience obtained significantly higher scores in all four main procedures - CI1 (ρ = 0.038), CI2 (ρ = 0.041), C1 (ρ = 0.032), P2 (ρ = 0.035) and IOL1 (ρ = 0.011). It was also found that experience improved the completion times in all modules - CI4 (ρ = 0.026), C4 (ρ = 0.018), P6 (ρ = 0.028) and IOL4 (ρ = 0.029). Positive correlation was observed between experience and anti-tremor - C2 (ρ = 0.026), P3 (ρ = 0.015), P4 (ρ = 0.042) and IOL2 (ρ = 0.048) and similarly with anti-rupture - CI3 (ρ = 0.013), C3 (ρ = 0.027), P5 (ρ = 0.021) and IOL3 (ρ = 0.041). No significant difference was observed between the groups with regards to P1 (ρ = 0.077).

CONCLUSIONS

Statistical analysis of the results obtained from repetitive trials between two groups of users reveal that augmented virtual reality (VR) simulators have the potential and capability to be used as a feasible proficiency assessment tool for the complete four main procedures of phacoemulsification cataract surgery (ρ < 0.05), indicating the construct validity of the modules simulated with augmented visual guidance and assessed through performance parameters.

Switching to instant black coffee modulates sodium selenite-induced cataract in rats

The influence of daily consumption of some common beverages on the development of cataract in rats was investigated. Total phenol content was determined in the beverages and an oral standardized dose of total phenols from each beverage was given to the treated rats. Weaned male albino rats were used and divided into five groups (n=7). Rats were fed Ain 93G and administered the standardized dose of instant coffee, black tea and hibiscus beverages for 30 days. On day 14 all rats were injected with a single dose of sodium selenite (Na₂SeO₃) 15 µmol/kg bodyweight, except the control groups NC (negative control, did not receive Na₂SeO₃) and PC (positive control, was already injected on day 1 of the study). The rats were continued on Ain 93G and the standardized dose for another 16 days. Positive control rats were used. Total phenols were 210, 40, and 44 mg/g dry weight gallic acid equivalent in black coffee, black tea, and hibiscus, respectively. Decreased levels (statistically significant P<0.05) of malondialdehyde, total nitric oxide, Ca-ATPase, tumor necrosis factor-α, interleukin-1β, superoxide dismutase, and conversely, increased levels (statistically significant P<0.05) of total protein, reduced glutathione, catalase were found in the lenses of the coffee group compared to PC. There are co-phenol substances in the instant black coffee that promoted coffee to be the most effective beverage.

Featured Article: Inhibition of diabetic cataract by glucose tolerance factor extracted from yeast

Diabetes leads to many complications; among them is the development of cataract. Hyperglycemia brings to increased polyol concentration in the lens, to glycation of lens proteins, and to elevated level of ROS (Reactive Oxygen Species) causing oxidative stress. The glucose tolerance factor (GTF) was found by several groups to decrease hyperglycemia and oxidative stress both in diabetic animals and humans. The aim of our study was to explore the damages induced by high glucose to the eye lens and to assess the protective effects of GTF both in vivo and in vitro The in vivo study included control healthy rats, streptozotocin (STZ) diabetic untreated rats, and STZ diabetic rats orally treated with 15 doses of GTF. The diabetic untreated rats developed cataracts, whereas the development of cataract was totally or partially prevented in GTF treated animals. In vitro studies were done on bovine lenses incubated for 14 days. Half of the lenses were incubated in normal glucose conditions, and half in high glucose conditions (450 mg%). To one group of the normal or high glucose condition GTF was added. The optical quality of all the lenses was measured daily by an automated scanning laser system. The control lenses, whether with or without GTF addition, did not show any reduction in their quality. High glucose conditions induced optical damage to the lenses. Addition of GTF to high glucose conditions prevented this damage. High glucose conditions affected the activity of aldose reductase and sodium potassium ATPase in lens epithelial cell. Addition of GTF decreased the destructive changes induced by high glucose conditions. The amount of soluble cortical lens proteins was decreased and structural changes were detected in lenses incubated in high glucose medium. These changes could be prevented when GTF was added to high glucose medium. Our findings demonstrate the anticataractogenic potential of GTF.

Differential regulation of aldose reductase expression during macrophage polarization depends on hyperglycemia

Aldose reductase (AR; gene AKR1B1) is the rate-limiting enzyme of the polyol pathway and has been associated with diabetes and atherosclerosis. Here, we sought to identify the mechanisms underlying differential AR expression in human atherosclerotic plaque macrophages. In vitro, M1-polarized human monocyte-derived macrophages expressed significantly higher levels of AKR1B1 mRNA and AR protein compared with M2-polarized macrophages. AR activity was significantly higher in M1 macrophages. AKR1B1 mRNA expression correlated positively with the M1 marker TNF(r = 0.430,P = 0.006) and negatively with the M2 marker MRC1 (r = -0.443,P = 0.044). Increased AR expression in M1 macrophages depended on hyperglycemia. Concomitantly, expression of SLC2A1 (coding for the Glc transporter GLUT-1) was significantly higher in M1 than in M2 macrophages. Pharmacological inhibition of GLUT-1 using STF-32 completely abrogated Glc-induced AR up-regulation in M1 macrophages. When analyzing AR expression in post-mortem coronary artery plaque macrophages, a history of diabetes was associated with a significantly increased proportion of CD68(+)AR(++)macrophages, supporting the in vivo relevance of our in vitro findings. We demonstrate that the phenotype of atherosclerotic plaque macrophages may be affected by cardiovascular risk factors such as hyperglycemia. Our data illustrate the complex interplay between systemic and local factors in atherogenesis.

Inhibitory Effect of Crocin(s) on Lens α-Crystallin Glycation and Aggregation, Results in the Decrease of the Risk of Diabetic Cataract

The current study investigates the inhibitory effect of crocin(s), also known as saffron apocarotenoids, on protein glycation and aggregation in diabetic rats, and α-crystallin glycation. Thus, crocin(s) were administered by intraperitoneal injection to normal and streptozotocin-induced diabetic rats. The cataract progression was recorded regularly every two weeks and was classified into four stages. After eight weeks, the animals were sacrificed and the parameters involved in the cataract formation were measured in the animal lenses. Some parameters were also determined in the serum and blood of the rats. In addition, the effect of crocin(s) on the structure and chaperone activity of α-crystallin in the presence of glucose was studied by different methods. Crocin(s) lowered serum glucose levels of diabetic rats and effectively maintained plasma total antioxidants, glutathione levels and catalase activity in the lens of the animals. In the in vitro study, crocin(s) inhibited α-crystallin glycation and aggregation. Advanced glycation end products fluorescence, hydrophobicity and protein cross-links were also decreased in the presence of crocin(s). In addition, the decreased chaperone activity of α-crystallin in the presence of glucose changed and became close to the native value by the addition of crocin(s) in the medium. Crocin(s) thus showed a powerful inhibitory effect on α-crystallin glycation and preserved the structure-function of this protein. Crocin(s) also showed the beneficial effects on prevention of diabetic cataract.