Photoreceptor Cells Influence Retinal Vascular Degeneration in Mouse Models of Retinal Degeneration and Diabetes

Purpose

Loss of photoreceptor cells is associated with retinal vascular degeneration in retinitis pigmentosa, whereas the presence of photoreceptor cells is implicated in vascular degeneration in diabetic retinopathy. To investigate how both the absence and presence of photoreceptors could damage the retinal vasculature, we compared two mouse models of photoreceptor degeneration (opsin^−/− and Rho^P23H/P23H ) and control C57Bl/5J mice, each with and without diabetes.

Methods

Retinal thickness, superoxide, expression of inflammatory proteins, ERG and optokinetic responses, leukocyte cytotoxicity, and capillary degeneration were evaluated at 1 to 10 months of age using published methods.

Results

Retinal photoreceptor cells degenerated completely in the opsin mutants by 2 to 4 months of age, and visual function subsided correspondingly. Retinal capillary degeneration was substantial while photoreceptors were still present, but slowed after the photoreceptors degenerated. Diabetes did not further exacerbate capillary degeneration in these models of photoreceptor degeneration, but did cause capillary degeneration in wild-type animals. Photoreceptor cells, however, did not degenerate in wild-type diabetic mice, presumably because the stress responses in these cells were less than in the opsin mutants. Retinal superoxide and leukocyte damage to retinal endothelium contributed to the degeneration of retinal capillaries in diabetes, and leukocyte-mediated damage was increased in both opsin mutants during photoreceptor cell degeneration.

Conclusions

Photoreceptor cells affect the integrity of the retinal microvasculature. Deterioration of retinal capillaries in opsin mutants was appreciable while photoreceptor cells were present and stressed, but was less after photoreceptors degenerated. This finding proves relevant to diabetes, where persistent stress in photoreceptors likewise contributes to capillary degeneration.

Elevated Activating Transcription Factor 4 and Glucose-Regulated 78 Kda Protein Levels Correlate with Inflammatory Cytokines in the Aqueous Humor and Vitreous of Proliferative Diabetic Retinopathy

PURPOSE

To determine concentrations of endoplasmic reticulum (ER) stress-related factors activating transcription factor 4 (ATF4) and glucose-regulated 78 kDa protein (GRP78) in vitreous and aqueous humor (AqH) of patients with proliferative diabetic retinopathy (PDR) and the correlation of ATF4, GRP78 and inflammatory cytokines interleukin-6(IL-6) and monocyte chemoattractant protein-1 (MCP-1).

MATERIALS AND METHODS

AqH and vitreous samples were collected from eyes of patients with PDR and idiopathic macular hole (IMH) which needed vitrectomy. Protein Levels of ATF4, GRP78, and IL-6, MCP-1 in samples were evaluated using enzyme-linked immunosorbent assay (ELISA).

RESULTS

ELISA analysis revealed significantly increased levels in both AqH and vitreous of ATF4 and GRP78 in eyes affected with PDR compared to the controls (all p < 0.001). The mean concentrations of IL-6, MCP-1 were also higher in both AqH and vitreous samples from patients with PDR compared to those of IMH (all p < 0.001). (Independent Student t-test, normality test followed with Skewness-Kurtosis Test). In addition, correlations of ATF4 and GRP78 with inflammatory factors IL-6 and MCP-1 in subjects of patients were analyzed. No significant correlation between the AqH concentrations of ATF4/IL-6 and ATF4/MCP-1 was detected in eyes of PDR patients (r = 0.346, p = 0.072 and r = 0.275, p = 0.157). Significant correlations were observed between AqH concentrations of GRP78/IL-6 (r = 0.724, p < 0.001), GRP78/MCP-1 (r = 0.654, p < 0.001) in PDR patients. Significant correlations were observed between vitreous concentrations of ATF4/IL-6 (r = 0.918, p < 0.001), ATF4/MCP-1 (r = 0.921, p < 0.001), GRP78/IL-6 (r = 0.978, p < 0.001), GRP78/MCP-1 (r = 0.979, p < 0.001) in PDR patients. No significant correlations was observed between AqH concentrations of ATF4/IL-6 (r = 0.187, p = 474), ATF4/MCP-1 (r = 0.240, p = 0.353), GRP78/IL-6 (r = 0.321, p = 0.209) and GRP78/MCP-1 (r = 0.169, p = 0.516) in eyes of IMH patients. And also no significant correlation was observed between vitreous concentrations of ATF4/IL-6 (r = 0.130, p = 0.563), ATF4/MCP-1(r = 0.029, p = 0.897), GRP78/IL-6 (r = 0.078, p = 0.717), GRP78/MCP-1 (r = 0.005, p = 0.982) in IMH patients. (Pearson correlation coefficient (two-tailed)).

CONCLUSIONS

Our results demonstrated that ATF4 and GRP78 may play an important role in the pathogenesis of PDR and work in concert with inflammatory cytokines IL-6 and MCP-1 in pathological process. ATF4 and GRP78 may be good diagnostic biomarkers and new therapeutic targets for PDR.

ABBREVIATIONS

ER stress, endoplasmic reticulum stress; ATF4, activating transcription factor 4; GRP78, glucose-regulated 78 kDa protein; AqH, aqueous humor; PDR, proliferative diabetic retinopathy; IL-6, interleukin-6; MCP-1, monocyte chemoattractant protein-1; IMH, idiopathic macular hole.

Do photoreceptor cells cause the development of retinal vascular disease?

The retinal vasculature is affected in a number of clinically important retinopathies, including diabetic retinopathy. There has been a considerable amount of research into the pathogenesis of retinal microvascular diseases, but the potential contribution of the most abundant cell population in the retina, photoreceptor cells, has been largely overlooked. This review summarizes ongoing research suggesting that photoreceptor cells play a critical role in the development of retinal vascular disease in diabetic retinopathy and other retinopathies.

CLINICAL ENDPOINTS FOR THE STUDY OF GEOGRAPHIC ATROPHY SECONDARY TO AGE-RELATED MACULAR DEGENERATION

PURPOSE

To summarize the recent literature describing the application of modern technologies in the study of patients with geographic atrophy (GA) secondary to age-related macular degeneration.

METHODS

Review of the literature describing the terms and definitions used to describe GA, imaging modalities used to capture and measure GA, and the tests of visual function and functional deficits that occur in patients with GA.

RESULTS

In this paper, we describe the evolution of the definitions used to describe GA. We compare imaging modalities used in the characterization of GA, report on the sensitivity and specificity of the techniques where data exist, and describe the correlations between these various modes of capturing the presence of GA. We review the functional tests that have been used in patients with GA, and critically examine their ability to detect and quantify visual deficits.

CONCLUSION

Ophthalmologists and retina specialists now have a wide range of assessments available for the functional and anatomic characterization of GA in patients with age-related macular degeneration. To date, studies have been limited by their unimodal approach, and we recommend that future studies of GA use multimodal imaging. We also suggest strategies for the optimal functional testing of patients with GA.

Coffee consumption prevents fibrosis in a rat model that mimics secondary biliary cirrhosis in humans

Investigations demonstrated that oxidative stress plays an important role in injury promotion in cholestatic liver disease. We hypothesized that coffee attenuates cholestasis-induced hepatic necrosis and fibrosis via its antioxidant, anti-inflammatory, and antifibrotic properties. The major aim of this study was to evaluate the hepatoprotective properties of coffee and caffeine in a model of chronic bile duct ligation (BDL) in male Wistar rats. Liver injury was induced by 28-day BDL, and conventional coffee, decaffeinated coffee, or caffeine was administered daily. After treatment, the hepatic oxidative status was estimated by measuring lipid peroxidation, the reduced to oxidized glutathione ratio, and glutathione peroxidase. Fibrosis was assessed by measuring the liver hydroxyproline content. The transforming growth factor-β, connective tissue growth factor, α-smooth muscle actin, collagen 1, and interleukin-10 proteins and mRNAs were measured by Western blot and polymerase chain reaction, respectively. Conventional coffee suppressed most of the changes produced by BDL; however, caffeine showed better antifibrotic effects. Coffee demonstrated antioxidant properties by restoring the redox equilibrium, and it also prevented the elevation of liver enzymes as well as hepatic glycogen depletion. Interestingly, coffee and caffeine administration prevented collagen increases. Western blot assays showed decreased expression levels of transforming growth factor-β, connective tissue growth factor, α-smooth muscle actin, and collagen 1 in the coffee- and caffeine-treated BDL groups. Similarly, coffee decreased the mRNA levels of these proteins. We conclude that coffee prevents liver cirrhosis induced by BDL by attenuating the oxidant processes, blocking hepatic stellate cell activation, and downregulating the main profibrotic molecules involved in extracellular matrix deposition.

Central Role of Metabolism in Endothelial Cell Function and Vascular Disease

The importance of endothelial cell (EC) metabolism and its regulatory role in the angiogenic behavior of ECs during vessel formation and in the function of different EC subtypes determined by different vascular beds has been recognized only in the last few years. Even more importantly, apart from a role of nitric oxide and reactive oxygen species in EC dysfunction, deregulations of EC metabolism in disease only recently received increasing attention. Although comprehensive metabolic characterization of ECs still needs further investigation, the concept of targeting EC metabolism to treat vascular disease is emerging. In this overview, we summarize EC-specific metabolic pathways, describe the current knowledge on their deregulation in vascular diseases, and give an outlook on how vascular endothelial metabolism can serve as a target to normalize deregulated endothelium.

Effects of caffeine consumption in patients with chronic hepatitis C: A systematic review and meta-analysis

BACKGROUND

Increased caffeine consumption has been associated with a decreased risk of liver enzyme elevation, cirrhosis, and hepatocellular carcinoma. However, few studies have assessed these effects in patients with chronic hepatitis C; therefore, we conducted a systematic review and meta-analysis to investigate the impact of caffeine consumption in patients with chronic hepatitis C infection.

METHODS

We performed a comprehensive search of the databases of the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE from inception through November 2015. The inclusion criterion was observational studies' assessment of the impact of caffeine consumption in adult patients with chronic hepatitis C.

RESULTS

Eleven studies were included for full article review, and data was extracted from five observational studies for meta-analysis. The pooled odds ratio of advanced hepatic fibrosis in patients who had higher caffeine intake was 0.39 (95% confidence interval 0.21-0.72, P=0.003) compared with lower caffeine intake group. The statistical between-study heterogeneity was moderate with an I² of 70%.

CONCLUSIONS

Our meta-analysis demonstrated that caffeine intake is significantly associated with decreased odds of advanced hepatic fibrosis in patients with chronic hepatitis C. Future prospective studies assessing the optimal dose and preparation of caffeinated beverages for prevention of hepatic fibrosis are needed.

Determinants of high unmet need for presbyopia correction: a community-based study in northwest Ethiopia

PURPOSE

Lack of evidence on the magnitude of unmet presbyopia need, and barriers to uptake spectacles, limit appropriate planning and implementation of the provision of spectacles to address the backlog of uncorrected presbyopia. The purpose of this study was to determine the magnitude of unmet presbyopia need and the associated factors in Bahir Dar, Ethiopia.

MATERIALS AND METHODS

A community-based cross-sectional study was conducted in 2015 in Bahir Dar. A multistage sampling technique was used to sample 729 study participants. Individuals more than 35 years of age who were unable to read the N8 line on a near vision chart unaided or with existing spectacles at 40 cm were considered as having unmet need for presbyopia correction. Distance and near visual acuities were measured by optometrists using Snellen illiterate E chart at 6 m and 40 m, respectively. Data were entered into Epi Info 2002 and analyzed using Statistical Package for Social Sciences version 16.0. Odds ratio (with 95% confidence interval [CI]) was used to determine the strength of association. P-values <0.05 were considered statistically significant.

RESULTS

A total of 729 people were included in the study (response rate of 99.5%). The mean age ± standard deviation of participants was 48.9±8.8 years. Unmet presbyopic need was 69.2% (95% CI: 65.8%-72.6%). Age (36-45 years [adjusted odds ratio {AOR} = 3.95; 95% CI: 1.06, 4.80]), having no eye checkup in the past 1 year (AOR = 8.36; 95% CI: 5.16, 13.7), lack of awareness about place of refraction service (AOR = 4.38; 95% CI: 1.36, 13.7), and female gender (AOR = 1.78; 95% CI: 1.68, 2.9) were determinants of unmet presbyopia need.

CONCLUSION

The burden of unmet presbyopia need is a high priority according to the World Health Organization prioritization for provision of presbyopia services. Accessible and affordable provision of spectacles with health education and promotion efforts are imperative to address the backlog of unmet presbyopia correction need in the study area.

Retinal oxygen: from animals to humans

This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O₂ in the retina: measurements of PO₂ with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O₂ concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO₂ in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.

Design, synthesis, molecular modeling and anti-hyperglycemic evaluation of novel quinoxaline derivatives as potential PPARγ and SUR agonists

In our effort to develop potent anti-hyperglycemic agents with potential agonistic activities toward PPARγ and SUR, three novel series of quinoxaline derivatives bearing sulfonylurea or sulfonylthiourea moieties with different linkers were designed and synthesized. Some of the newly synthesized compounds were evaluated in vivo for their anti-hyperglycemic activities in STZ-induced hyperglycemic rats. Compounds 15_a, 15_e, 19_b and 24_a exhibited the highest anti-hyperglycemic activities with % reduction in blood glucose level of (50.58, 43.84, 45.10 and 49.62, respectively). Additionally, eight compounds revealed potent anti-hyperglycemic activities were further evaluated in vitro for their PPARγ binding affinity and insulin-secreting ability as potential mechanisms for anti-hyperglycemic activity. Four compounds (15_a, 15_b, 15_d and 15_e) significantly bound to PPARγ with IC₅₀ values of 0.482, 0.491, 0.350 and 0.369μM, respectively. Moreover, Compounds 15_a and 15_b have demonstrated induction of insulin-secretion with EC₅₀ values of 0.92 and 0.98μM, respectively. Furthermore, molecular docking and pharmacophore generation techniques were carried out to investigate binding patterns and fit values of the designed compounds with PPARγ and SUR, respectively.

Coffee Intake Is Associated with a Lower Liver Stiffness in Patients with Non-Alcoholic Fatty Liver Disease, Hepatitis C, and Hepatitis B

There is emerging evidence for the positive effects or benefits of coffee in patients with liver disease. We conducted a retrospective cross-sectional study on patients with non-alcoholic fatty liver disease (NAFLD), hepatitis C virus (HCV), and hepatitis B virus (HBV) infection to determine the effects of coffee intake on a non-invasive marker of liver fibrosis: liver stiffness assessed by transient elastography (TE). We assessed coffee and tea intake and measured TE in 1018 patients with NAFLD, HCV, and HBV (155 with NAFLD, 378 with HCV and 485 with HBV). Univariate and multivariate regression models were performed taking into account potential confounders. Liver stiffness was higher in males compared to females (p < 0.05). Patients with HBV had lower liver stiffness than those with HCV and NAFLD. After adjustment for age, gender, smoking, alcohol consumption, M or XL probe, and disease state (NAFLD, HCV, and HBV status), those who drank 2 or more cups of coffee per day had a lower liver stiffness (p = 0.044). Tea consumption had no effect (p = 0.9). Coffee consumption decreases liver stiffness, which may indicate less fibrosis and inflammation, independent of disease state. This study adds further evidence to the notion of coffee maybe beneficial in patients with liver disease.

Impact of caffeine in hepatitis C virus infection: a systematic review and meta-analysis

BACKGROUND/OBJECTIVES

Hepatitis C virus (HCV) infection is one of the most common causes of cirrhosis. Several studies have linked caffeine consumption to a lower degree of liver fibrosis and inflammation among patients with chronic HCV infection, but the results were inconsistent. This meta-analysis was carried out with the aim of assessing the impact of caffeine consumption among HCV-infected patients.

PARTICIPANTS AND METHODS

A literature search was performed using MEDLINE and EMBASE from inception to January 2016. Studies that reported relative risks, odd ratios, or hazard ratios comparing the risk of advanced liver fibrosis or the risk of moderate to severe liver inflammation among HCV-infected patients who consumed caffeine on a regular basis versus those who did not were included. Pooled odds ratios (OR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse-variance method.

RESULTS

Five studies were included in the fibrosis analysis. The pooled OR of advanced liver fibrosis in HCV-infected patients who consumed caffeine on a regular basis versus those who did not was 0.48 (95% CI, 0.30-0.76, I=52%). Three studies were included in the inflammation analysis. The pooled OR of moderate to severe histologic inflammation among HCV-infected patients who consumed caffeine on a regular basis versus those who did not was 0.61 (95% CI, 0.35-1.04, I=43%).

CONCLUSION

Our study showed a decreased risk of advanced liver fibrosis and liver inflammation among HCV-infected patients who consumed caffeine on a regular basis. Whether consumption of caffeine plays a role in the management of HCV infection requires further investigations.

Main visual symptoms associated to refractive errors and spectacle need in a Brazilian population

AIM

To determine the main visual symptoms in a Brazilian population sample, associated to refractive errors (REs) and spectacle need to suggest priorities in preventive programs.

METHODS

A cross-sectional study was conducted in nine counties of the southeast region of Brazil, using a systematic sampling of households, between March 2004 and July 2005. The population was defined as individuals aged between 1 and 96y, inhabitants of 3600 residences to be evaluated and 3012 households were included, corresponding to 8010 subjects considered for participation in the survey, of whom 7654 underwent ophthalmic examinations. The individuals were evaluated according their demographic data, eye complaints and eye examination including the RE and the need to prescribe spectacles according to age. Statistical analysis was performed using SPSS software package and descriptive analysis using 95% confidence intervals (P<0.05).

RESULTS

The main symptom detected was asthenopia, most frequent in the 2^nd and 3^rd decades of life, with a significant decline after the 4^th decade. Astigmatism was the RE most associated with asthenopia. Reduced near vision sight was more frequent in those ≥40y with a progressive decline thereafter. Spectacles were most frequently required in subjects of ≥40 years of age.

CONCLUSION

The main symptom related to the vision was asthenopia and was associated to astigmatism. The greatest need for spectacles prescription occurred after 40's, mainly to correct near vision. Subjects of ≥40 years old were determined to be at high risk of uncorrected REs. These observations can guide intervention programs for the Brazilian population.

Serum Autoantibody Profiling of Patients with Paraneoplastic and Non-Paraneoplastic Autoimmune Retinopathy

PURPOSE

Although multiple serum antiretinal autoantibodies (ARAs) have been reported in patients with paraneoplastic and non-paraneoplastic autoimmune retinopathy ((n)pAIR), not all retinal antigens involved in (n)pAIR are specified. This study aims to serologically identify patients with presumed (n)pAIR through determination of both known and unknown ARAs by autoantibody profiling.

METHODS

An antigen suspension bead array using 188 different antigens representing 97 ocular proteins was performed to detect ARAs in serum samples of patients with presumed (n)pAIR (n = 24), uveitis (n = 151) and cataract (n = 21). Logistic regressions were used to estimate the associations between ocular antigens and diagnosis. Validation of interphotoreceptor matrix proteoglycan 2 (IMPG2) and recoverin antigens was performed by immunohistochemistry and immunoblot, respectively.

RESULTS

Samples of patients with presumed (n)pAIR exhibited a broad spectrum of ARAs. We identified retinal antigens that have already been described previously (e.g. recoverin), but also identified novel ARA targets. Most ARAs were not specific for (n)pAIR since their presence was also observed in patients with cataract or uveitis. High titers of autoantibodies directed against photoreceptor-specific nuclear receptor and retinol-binding protein 3 were more common in patients with presumed (n)pAIR compared to uveitis (p = 0.015 and p = 0.018, respectively). The presence of all other ARAs did not significantly differ between groups. In patients with presumed (n)pAIR, anti-recoverin autoantibodies were the most prevalent ARAs. Validation of bead array results by immunohistochemistry (anti-IMPG2) and immunoblot (anti-recoverin) showed concordant results in (n)pAIR patients.

CONCLUSIONS

Patients with (n)pAIR are characterized by the presence of a broad spectrum of ARAs. The diagnosis of (n)pAIR cannot be based on the mere presence of serum ARAs, as these are also commonly present in uveitis as well as in age-related cataract patients.

Nap Interferes with Hypoxia-Inducible Factors and VEGF Expression in Retina of Diabetic Rats

The retinal microvascular damage is a complication of diabetic retinopathy (DR). Hyperglycemia and hypoxia are responsible of aberrant vessel's proliferation. The cellular response to hypoxia is mediated through activation of hypoxia-inducible factors (HIFs). Among these, HIF-1α modulates expression of its target gene, VEGF, whose upregulation controls the angiogenic event during DR development. In a previous study, we have demonstrated that a small peptide, NAP, is able to protect retina from hyperglycemic insult. Here, we have demonstrated that its intraocular administration in a rat model of diabetic retinopathy has reduced expression of HIF-1α, HIF-2α, and VEGF by increasing HIF-3α levels. These data have been also confirmed by immunolocalization study by confocal microscopy. Although these evidences need to be further deepened to understand the molecular mechanism involved in the protective NAP action, the present data suggest that this small peptide may be effective to prevent the development of this ocular pathology.

Mechanical properties of protective spectacles fitted with corrective lenses

The majority of commercially available corrective spectacles used by workers do not provide effective eye protection against mechanical hazards in the workplace. One of the risks commonly occurring during work is hitting the head on some protruding elements, such as components of machines, buildings or tree branches in a forest. Because of the considerable weight of the human head and the speed of movement during impact, this type of accident may be very serious. This article presents a method of testing the mechanical strength of corrective lenses, simulating the results of an impact of the head on elements of workplaces. The results of tests of commercially available materials used for the construction of corrective and protective spectacles are also presented and discussed.

Identification of type 2 diabetes subgroups through topological analysis of patient similarity

Type 2 diabetes (T2D) is a heterogeneous complex disease affecting more than 29 million Americans alone with a rising prevalence trending toward steady increases in the coming decades. Thus, there is a pressing clinical need to improve early prevention and clinical management of T2D and its complications. Clinicians have understood that patients who carry the T2D diagnosis have a variety of phenotypes and susceptibilities to diabetes-related complications. We used a precision medicine approach to characterize the complexity of T2D patient populations based on high-dimensional electronic medical records (EMRs) and genotype data from 11,210 individuals. We successfully identified three distinct subgroups of T2D from topology-based patient-patient networks. Subtype 1 was characterized by T2D complications diabetic nephropathy and diabetic retinopathy; subtype 2 was enriched for cancer malignancy and cardiovascular diseases; and subtype 3 was associated most strongly with cardiovascular diseases, neurological diseases, allergies, and HIV infections. We performed a genetic association analysis of the emergent T2D subtypes to identify subtype-specific genetic markers and identified 1279, 1227, and 1338 single-nucleotide polymorphisms (SNPs) that mapped to 425, 322, and 437 unique genes specific to subtypes 1, 2, and 3, respectively. By assessing the human disease-SNP association for each subtype, the enriched phenotypes and biological functions at the gene level for each subtype matched with the disease comorbidities and clinical differences that we identified through EMRs. Our approach demonstrates the utility of applying the precision medicine paradigm in T2D and the promise of extending the approach to the study of other complex, multifactorial diseases.

Dynamic Regulation of the GABAA Receptor Function by Redox Mechanisms

Oxidizing and reducing agents, which are currently involved in cell metabolism and signaling pathways, can regulate fast inhibitory neurotransmission mediated by GABA receptors in the nervous system. A number of in vitro studies have shown that diverse redox compounds, including redox metabolites and reactive oxygen and nitrogen species, modulate phasic and tonic responses mediated by neuronal GABAA receptors through both presynaptic and postsynaptic mechanisms. We review experimental data showing that many redox agents, which are normally present in neurons and glia or are endogenously generated in these cells under physiologic states or during oxidative stress (e.g., hydrogen peroxide, superoxide and hydroxyl radicals, nitric oxide, ascorbic acid, and glutathione), induce potentiating or inhibiting actions on different native and recombinant GABAA receptor subtypes. Based on these results, it is thought that redox signaling might represent a homeostatic mechanism that regulates the function of synaptic and extrasynaptic GABAA receptors in physiologic and pathologic conditions.

Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan

Caloric restriction (CR), defined as decreased nutrient intake without causing malnutrition, has been documented to increase both health and lifespan across numerous organisms, including humans. Many drugs and other compounds naturally occurring in our diet (nutraceuticals) have been postulated to act as mimetics of caloric restriction, leading to a wave of research investigating the efficacy of these compounds in preventing age-related diseases and promoting healthier, longer lifespans. Although well studied at the biochemical level, there are still many unanswered questions about how CR and CR mimetics impact genome function and structure. Here we discuss how genome function and structure are influenced by CR and potential CR mimetics, including changes in gene expression profiles and epigenetic modifications and their potential to identify the genetic fountain of youth.

Early Retinal Neuronal Dysfunction in Diabetic Mice: Reduced Light-Evoked Inhibition Increases Rod Pathway Signaling

Purpose

Recent studies suggest that the neural retinal response to light is compromised in diabetes. Electroretinogram studies suggest that the dim light retinal rod pathway is especially susceptible to diabetic damage. The purpose of this study was to determine whether diabetes alters rod pathway signaling.

Methods

Diabetes was induced in C57BL/6J mice by three intraperitoneal injections of streptozotocin (STZ; 75 mg/kg), and confirmed by blood glucose levels > 200 mg/dL. Six weeks after the first injection, whole-cell voltage clamp recordings of spontaneous and light-evoked inhibitory postsynaptic currents from rod bipolar cells were made in dark-adapted retinal slices. Light-evoked excitatory currents from rod bipolar and AII amacrine cells, and spontaneous excitatory currents from AII amacrine cells were also measured. Receptor inputs were pharmacologically isolated. Immunohistochemistry was performed on whole mounted retinas.

Results

Rod bipolar cells had reduced light-evoked inhibitory input from amacrine cells but no change in excitatory input from rod photoreceptors. Reduced light-evoked inhibition, mediated by both GABA_A and GABA_C receptors, increased rod bipolar cell output onto AII amacrine cells. Spontaneous release of GABA onto rod bipolar cells was increased, which may limit GABA availability for light-evoked release. These physiological changes occurred in the absence of retinal cell loss or changes in GABA_A receptor expression levels.

Conclusions

Our results indicate that early diabetes causes deficits in the rod pathway leading to decreased light-evoked rod bipolar cell inhibition and increased rod pathway output that provide a basis for the development of early diabetic visual deficits.

Metformin attenuates graft-versus-host disease via restricting mammalian target of rapamycin/signal transducer and activator of transcription 3 and promoting adenosine monophosphate-activated protein kinase-autophagy for the balance between T helper 17 and Tregs

Acute graft-versus-host disease (aGVHD), caused by donor T cell-mediated injury to host tissues, is a problem in allogeneic bone marrow transplantation. The transition from naïve to effector T cells is accompanied by shift in metabolism main pathway; from glucose oxidative phosphorylation to aerobic glycolysis. Adenosine monophosphate-activated protein kinase (AMPK) is a serine/threonine kinase that is a metabolic sensor that helps maintain cellular energy homeostasis. Although AMPK activation can exert anti-inflammatory properties by negatively regulating pro-inflammatory mediators, its role as a therapeutic potential of graft-versus-host disease development remains unclear. In this study, we found that the intraperitoneal administration of metformin, which activates AMPK signaling significantly, ameliorated the clinical severity of aGHVD and lethality. This was associated with reductions in type I T helper (Th1) and Th17 and rises in Th2 and regulatory T (Treg) cell. The enhanced signal transducer and activator of transcription 3 activation noted during the development of aGVHD was reduced by metformin treatment. Furthermore, metformin-treated Th17 cells became converted into Treg cells via enhanced autophagy. The reduction in mortality associated with metformin treatment was associated with inhibition of the mammalian target of rapamycin/signal transducer and activator of transcription 3 pathway. These results suggest that metformin might be of significant use in the treatment of patients with aGVHD.

Manipulating Angiogenesis by Targeting Endothelial Metabolism: Hitting the Engine Rather than the Drivers-A New Perspective?

Excessive angiogenesis (i.e., the formation of new blood vessels) contributes to different pathologies, among them cancer and ocular disorders. Conversely, dysfunction of endothelial cells (ECs) contributes to cardiovascular complications, as is the case in diabetes. Inhibition of pathologic angiogenesis in blinding eye disease and cancer by targeting growth factors such as vascular endothelial growth factor has become an accepted therapeutic strategy. However, recent studies also unveiled the emerging importance of EC metabolism in controlling angiogenesis. In this overview, we will discuss recent insights in the metabolic regulation of angiogenesis, focusing on the best-characterized metabolic pathways, and highlight deregulation of EC metabolism in cancer and diabetes. We will give an outlook on how targeting EC metabolism can be used for blocking pathologic angiogenesis and for normalizing EC dysfunction.

Proteomic modulation in breast tumors after metformin exposure: results from a "window of opportunity" trial

PURPOSE

Reverse Phase Protein Array (RPPA) is a high-throughput antibody-based technique to assess cellular protein activity. The goal of this study was to assess protein marker changes by RPPA in tumor tissue from a pre-surgical metformin trial in women with operable breast cancer (BC).

METHODS

In an open-label trial, metformin 1500-mg PO daily was administered prior to resection in 35 non-diabetic patients with stage 0-III BC, body mass index ≥25 kg/m². For RPPA, formalin-fixed paraffin-embedded (FFPE) samples were probed with 160 antibodies. Paired and two-sample t-tests were performed (p ≤ 0.05). Multiple comparisons were adjusted for by fixing the false discovery rate at 25 %. We evaluated whether pre- and post-metformin changes of select markers by RPPA were identified by immunohistochemistry (IHC) in these samples. We also assessed for these changes by western blot in metformin-treated BC cell lines.

RESULTS

After adjusting for multiple comparisons in the 32 tumors from metformin-treated patients vs. 34 untreated historical controls, 11 proteins were significantly different between cases vs.

CONTROLS

increases in Raptor, C-Raf, Cyclin B1, Cyclin D1, TRFC, and Syk; and reductions in pMAPK^pT202,Y204, JNK^pT183,pT185, Bad^pS112, PKC.alpha^pS657, and Src^pY416. Cyclin D1 change after metformin by IHC was not observed. In cell lines, reductions in JNK^pT183 and Bad^pS112 were seen, with no change in Cyclin D1 or Raptor.

CONCLUSIONS

These results suggest that metformin modulates apoptosis/cell cycle, cell signaling, and invasion/motility. These findings should be assessed in larger metformin trials. If confirmed, associations between these changes and BC clinical outcome should be evaluated. CLINICALTRIALS.

GOV IDENTIFIER

NCT00930579.

Retinal Electrophysiological Effects of Intravitreal Bone Marrow Derived Mesenchymal Stem Cells in Streptozotocin Induced Diabetic Rats

Diabetic retinopathy is the most common cause of legal blindness in developed countries at middle age adults. In this study diabetes was induced by streptozotocin (STZ) in male Wistar albino rats. After 3 months of diabetes, rights eye were injected intravitreally with green fluorescein protein (GFP) labelled bone marrow derived stem cells (BMSC) and left eyes with balanced salt solution (Sham). Animals were grouped as Baseline (n = 51), Diabetic (n = 45), Diabetic+BMSC (n = 45 eyes), Diabetic+Sham (n = 45 eyes), Healthy+BMSC (n = 6 eyes), Healthy+Sham (n = 6 eyes). Immunohistology analysis showed an increased retinal gliosis in the Diabetic group, compared to Baseline group, which was assessed with GFAP and vimentin expression. In the immunofluorescence analysis BMSC were observed to integrate mostly into the inner retina and expressing GFP. Diabetic group had prominently lower oscillatory potential wave amplitudes than the Baseline group. Three weeks after intravitreal injection Diabetic+BMSC group had significantly better amplitudes than the Diabetic+Sham group. Taken together intravitreal BMSC were thought to improve visual function.

Pioglitazone inhibits growth of human retinoblastoma cells via regulation of NF-κB inflammation signals

OBJECTIVES

We aimed to study the antitumor effects of the PPARγ agonist pioglitazone on human retinoblastoma.

METHODS

The effects of pioglitazone on cell proliferation and apoptosis of the human retinoblastoma Y79 cells were investigated by MTT assay and Hoechst 33258 staining assay. The apoptosis related protein levels were detected by western blot. Inflammationary factors analysis was evaluated by western blot and ELISA. The effect of pioglitazone on nuclear factor-kappa B (NF-κB)-dependent reporter gene transcription induced by LPS was analyzed by NF-κB-luciferase assay. Then human retinoblastoma Y79 cells were subcutaneously transplanted in BALB/c nude mice and the animals were treated with pioglitazone to verify its antitumor effect in vivo.

RESULTS

Our data revealed that pioglitazone suppressed the viability of Y79 cells dose- and time-dependently and induced apoptosis in Y79 cells in vitro. Molecular biology analysis found that pioglitazone could affect the apoptosis and inflammation related signal via modulating the activity of NF-κB signal. Also we found that pioglitazone could markedly reduce the growth of Y79 cells transplanted into the mice without causing significant side effects.

CONCLUSIONS

Our results suggested that pioglitazone demonstrated antitumor activity against the human retinoblastoma Y79 cells by inhibiting cell growth, inducing apoptosis and modulating NF-κB pathway, and thus delayed tumor growth in vivo.

Intravitreal administration of multipotent mesenchymal stromal cells triggers a cytoprotective microenvironment in the retina of diabetic mice

Background

Diabetic retinopathy is a common complication of diabetes and the leading cause of irreversible vision loss in the Western world. The reduction in color/contrast sensitivity due to the loss of neural cells in the ganglion cell layer of the retina is an early event in the onset of diabetic retinopathy. Multipotent mesenchymal stromal cells (MSCs) are an attractive tool for the treatment of neurodegenerative diseases, since they could differentiate into neuronal cells, produce high levels of neurotrophic factors and reduce oxidative stress. Our aim was to determine whether the intravitreal administration of adipose-derived MSCs was able to prevent the loss of retinal ganglion cells in diabetic mice.

Methods

Diabetes was induced in C57BL6 mice by the administration of streptozotocin. When retinal pro-damage mechanisms were present, animals received a single intravitreal dose of 2 × 10⁵ adipose-derived MSCs or the vehicle. Four and 12 weeks later we evaluated: (a) retinal ganglion cell number (immunofluorescence); (b) neurotrophic factor levels (real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA)); (c) retinal apoptotic rate (TUNEL); (d) retinal levels of reactive oxygen species and oxidative damage (ELISA); (e) electrical response of the retina (electroretinography); (f) pro-angiogenic and anti-angiogenic factor levels (RT-qPCR and ELISA); and (g) retinal blood vessels (angiography). Furthermore, 1, 4, 8 and 12 weeks post-MSC administration, the presence of donor cells in the retina and their differentiation into neural and perivascular-like cells were assessed (immunofluorescence and flow cytometry).

Results

MSC administration completely prevented retinal ganglion cell loss. Donor cells remained in the vitreous cavity and did not differentiate into neural or perivascular-like cells. Nevertheless, they increased the intraocular levels of several potent neurotrophic factors (nerve growth factor, basic fibroblast growth factor and glial cell line-derived neurotrophic factor) and reduced the oxidative damage in the retina. Additionally, MSC administration has a neutral effect on the electrical response of the retina and did not result in a pathological neovascularization.

Conclusions

Intravitreal administration of adipose-derived MSCs triggers an effective cytoprotective microenvironment in the retina of diabetic mice. Thus, MSCs represent an interesting tool in order to prevent diabetic retinopathy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0299-y) contains supplementary material, which is available to authorized users.

Coffee and Liver Disease

Coffee is the most popular beverage in the world. Consumption of coffee has been shown to benefit health in general, and liver health in particular. This article reviews the effects of coffee intake on development and progression of liver disease due to various causes. We also describe the putative mechanisms by which coffee exerts the protective effect. The clinical evidence of benefit of coffee consumption in Hepatitis B and C, as well as nonalcoholic fatty liver disease and alcoholic liver disease, has also been presented. Coffee consumption is associated with improvement in liver enzymes (ALT, AST, and GGTP), especially in individuals with risk for liver disease. Coffee intake more than 2 cups per day in patients with preexisting liver disease has been shown to be associated with lower incidence of fibrosis and cirrhosis, lower hepatocellular carcinoma rates, as well as decreased mortality.

The TRPM1 channel in ON-bipolar cells is gated by both the α and the βγ subunits of the G-protein Go

Transmission from photoreceptors to ON bipolar cells in mammalian retina is mediated by a sign-inverting cascade. Upon binding glutamate, the metabotropic glutamate receptor mGluR6 activates the heterotrimeric G-protein Gα_oβ3γ13, and this leads to closure of the TRPM1 channel (melastatin). TRPM1 is thought to be constitutively open, but the mechanism that leads to its closure is unclear. We investigated this question in mouse rod bipolar cells by dialyzing reagents that modify the activity of either Gα_o or Gβγ and then observing their effects on the basal holding current. After opening the TRPM1 channels with light, a constitutively active mutant of Gα_o closed the channel, but wild-type Gα_o did not. After closing the channels by dark adaptation, phosducin or inactive Gα_o (both sequester Gβγ) opened the channel while the active mutant of Gα_o did not. Co-immunoprecipitation showed that TRPM1 interacts with Gβ3 and with the active and inactive forms of Gα_o. Furthermore, bioluminescent energy transfer assays indicated that while Gα_o interacts with both the N- and the C- termini of TRPM1, Gβγ interacts only with the N-terminus. Our physiological and biochemical results suggest that both Gα_o and Gβγ bind TRPM1 channels and cooperate to close them.

Spare the rods and spoil the retina: revisited

Visual function improves with oxygen inhalation in people with diabetes even in the absence of visible retinopathy. Rods consume the most oxygen in the retina due to the high metabolic activity required to maintain the dark current. Therefore, Arden hypothesized that in diabetes where oxygen supply may also be affected due to the changes in retinal vasculature, prevention of dark adaptation may be a viable option to prevent or decrease the rate of progression of diabetic retinopathy. Animal experiments have proven that the absence of rods decreases the development of retinal neovascularisation. The same principle applies to panretinal photocoagulation, an established treatment for proliferative diabetic retinopathy. Recently, a few clinical studies have also shown that preventing dark adaptation by suppressing rods with 500-nm light source at night decreases the rate of progression of early diabetic retinopathy and maculopathy in the short-term. We await the results of a large two-year multi-centre trial (CLEOPATRA trial) to evaluate the long-term effects of decreasing dark adaptation by applying a 500nm light source as a mask over eyes with non-central diabetic macular oedema.

RNA sequencing reveals retinal transcriptome changes in STZ-induced diabetic rats

The present study aimed to investigate changes in retinal gene expression in streptozotocin (STZ)‑induced diabetic rats using next‑generation sequencing, utilize transcriptome signatures to investigate the molecular mechanisms of diabetic retinopathy (DR), and identify novel strategies for the treatment of DR. Diabetes was chemically induced in 10‑week‑old male Sprague‑Dawley rats using STZ. Flash‑electroretinography (F‑ERG) was performed to evaluate the visual function of the rats. The retinas of the rats were removed to perform high throughput RNA sequence (RNA‑seq) analysis. The a‑wave, b‑wave, oscillatory potential 1 (OP1), OP2 and ∑OP amplitudes were significantly reduced in the diabetic group, compared with those of the control group (P<0.05). Furthermore, the implicit b‑wave duration 16 weeks post‑STZ induction were significantly longer in the diabetic rats, compared with the control rats (P<0.001). A total of 868 genes were identified, of which 565 were upregulated and 303 were downregulated. Among the differentially expressed genes (DEGs), 94 apoptotic genes and apoptosis regulatory genes, and 19 inflammatory genes were detected. The results of the KEGG pathway significant enrichment analysis revealed enrichment in cell adhesion molecules, complement and coagulation cascades, and antigen processing and presentation. Diabetes alters several transcripts in the retina, and RNA‑seq provides novel insights into the molecular mechanisms underlying DR.

Ion Channels in the Eye: Involvement in Ocular Pathologies

The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.

Hypoxia and Dark Adaptation in Diabetic Retinopathy: Interactions, Consequences, and Therapy

In diabetes, retinal blood flow is compromised, and retinal hypoxia is likely to be further intensified during periods of darkness. During dark adaptation, rod photoreceptors in the outer retina are maximally depolarized and continuously release large amounts of the neurotransmitter glutamate-an energetically demanding process that requires the highest oxygen consumption per unit volume of any tissue of the body. In complete darkness, even more oxygen is consumed by the outer retina, producing a steep fall in the retinal oxygen tension curve which reaches a nadir at the depth of the mitochondrial-rich rod inner segments. In contrast to the normal retina, the diabetic retina cannot meet the added metabolic load imposed by the dark-adapted rod photoreceptors; this exacerbates retinal hypoxia and stimulates the overproduction of vascular endothelial growth factor (VEGF). The use of nocturnal illumination to prevent dark adaptation, specifically reducing the rod photoreceptor dark current, should ameliorate diabetic retinopathy.

Geographic atrophy in patients with advanced dry age-related macular degeneration: current challenges and future prospects

Geographic atrophy (GA) of the retinal pigment epithelium (RPE) is a devastating complication of age-related macular degeneration (AMD). GA may be classified as drusen-related (drusen-associated GA) or neovascularization-related (neovascular-associated GA). Drusen-related GA remains a large public health concern due to the burden of blindness it produces, but pathophysiology of the condition is obscure and there are no proven treatment options. Genotyping, cell biology, and clinical imaging point to upregulation of parainflammatory pathways, oxidative stress, and choroidal sclerosis as contributors, among other factors. Onset and monitoring of progression is accomplished through clinical imaging instrumentation such as optical coherence tomography, photography, and autofluorescence, which are the tools most helpful in determining end points for clinical trials at present. A number of treatment approaches with diverse targets are in development at this time, some of which are in human clinical trials. Neovascular-associated GA is a consequence of RPE loss after development of neovascular AMD. The neovascular process leads to a plethora of cellular stresses such as ischemia, inflammation, and dramatic changes in cell environment that further taxes RPE cells already dysfunctional from drusen-associated changes. GA may therefore develop secondary to the neovascular process de novo or preexisting drusen-associated GA may continue to worsen with the development of neovascular AMD. Neovascular-associated GA is a prominent cause of continued vision loss in patients with otherwise successfully treated neovascular AMD. Clearly, treatment with vascular endothelial growth factor (VEGF) inhibitors early in the course of the neovascular disease is of great clinical benefit. However, there is a rationale and some suggestive evidence that anti-VEGF agents themselves could be toxic to RPE and enhance neovascular-associated GA. The increasing prevalence of legal blindness from this condition due to the aging of the general population lends urgency to the search for a therapy to ameliorate GA.

Overexpression of melanopsin in the retina restores visual function in Royal College of Surgeons rats

Retinitis pigmentosa (RP) is a pathological condition leading to progressive visual decline resulting from continual loss of photoreceptor cells and outer nuclear layers of the retina. The aim of the present study was to explore whether melanopsin was able to restore retinal function and inhibit its degeneration by acting in a similar manner to channel rhodopsins. Royal College of Surgeons rats, which were used as an animal model of inherited retinal degeneration, were subjected to sub-retinal injection with melanopsin overexpression vector (AV‑OPN4‑GFP). Immunohistochemical and western blot analyses were used to detect the distribution and protein expression of melanopsin in the retina, revealing that melanopsin was gradually reduced with increasing age of the rats, which was due to loss of dendritic axons of intrinsically photosensitive retinal ganglion cells. Animals injected into both eyes were subjected to a behavioral open-field test, revealing that melanopsin overexpression reduced the loss of light sensitivity of the rats. In a flash electroretinography experiment, the b‑wave and response to light flash stimuli at three and five weeks following injection with AV‑OPN4‑GFP were higher compared to those in eyes injected with AV‑GFP (P<0.05). In conclusion, the present study showed that during retinal degeneration, the expression of melanopsin was significantly decreased, while vector-mediated overexpression of melanopsin delayed the loss of visual function in rats.

Coffee Consumption Decreases Risks for Hepatic Fibrosis and Cirrhosis: A Meta-Analysis

BACKGROUND AND AIM

Previous studies have demonstrated that coffee consumption may be inversely correlated with hepatic fibrosis and cirrhosis. However, the reported results have been inconsistent. To summarize previous evidences quantitatively, a meta-analysis was performed.

METHODS

The Medline, Web of Science, and Embase databases (from inception to June 2015) were searched to identify relevant trials that evaluated the effects of coffee consumption on hepatic fibrosis or cirrhosis. Odds ratios (ORs) of advanced hepatic fibrosis or cirrhosis for low or moderate, high, and any coffee consumption versus no consumption were pooled. Two cups per day was used as the cut-off level between low or moderate and high consumption.

RESULTS

Sixteen studies were included, involving 3034 coffee consumers and 132076 people who do not consume coffee. The pooled results of the meta-analysis indicated that coffee consumers were less likely to develop cirrhosis compared with those who do not consume coffee, with a summary OR of 0.61 (95%CI: 0.45-0.84). For low or moderate coffee consumption versus no consumption, the pooled OR of hepatic cirrhosis was 0.66 (95%CI: 0.47-0.92). High coffee consumption could also significantly reduce the risk for hepatic cirrhosis when compared with no coffee consumption (OR = 0.53, 95%CI: 0.42-0.68). The effect of coffee consumption on hepatic fibrosis was summarized as well. The pooled OR of advanced hepatic fibrosis for coffee consumption versus no consumption was 0.73 (95%CI: 0.58-0.92). The protective effect of coffee on hepatic fibrosis and cirrhosis was also identified in subgroup meta-analyses of patients with alcoholic liver disease and chronic hepatitis C virus (HCV) infection.

CONCLUSION

Coffee consumption can significantly reduce the risk for hepatic fibrosis and cirrhosis.

Intravitreal Injection--Technique and Safety

Intravitreal (IVT) injection of therapeutic agents has become one of the most commonly performed procedures in ophthalmology. Over the past decade, a number of guidelines have been published that recommend proper techniques to increase the safety of IVT injections. Among the various complications of IVT injections, endophthalmitis can be sight threatening. The reported endophthalmitis rates after IVT injection range from 0.020% to 0.085%, which are higher than what would be expected from a simple, fast, and relatively atraumatic procedure. The 2 key issues involved in the prevention of endophthalmitis are pre-IVT injection disinfection using povidone-iodine (PVI) and the use of topical antibiotics as prophylaxis. Whereas 5% PVI for 5 minutes is most commonly used in cataract surgery for disinfection, the duration in IVT injection is much less and can be as short as 30 seconds. Further studies seem warranted to investigate whether longer duration of PVI application in IVT injection can lower the endophthalmitis rate. Recent data suggest that there is inadequate evidence to support the routine use of prophylactic pre-, peri-, or postinjection antibiotics to reduce the risk of endophthalmitis. However, as many confounding factors such as the PVI regimens were not standardized in previous studies, it is too soon to make a concrete conclusion. Despite the availability of published guidelines, considerable variations still exist in real-life clinical situations. In this article, we describe our IVT injection practice protocol and compare it with the most recent international guidelines. Finally, a summary table that shows the clinical features of true, sterile, and pseudoendophthalmitis is presented.

High Glucose-induced Retinal Pericyte Apoptosis Depends on Association of GAPDH and Siah1

Diabetic retinopathy (DR) is a leading cause of blindness worldwide, and its prevalence is growing. Current therapies for DR address only the later stages of the disease, are invasive, and have limited effectiveness. Retinal pericyte death is an early pathologic feature of DR. Although it has been observed in diabetic patients and in animal models of DR, the cause of pericyte death remains unknown. A novel pro-apoptotic pathway initiated by the interaction between glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the E3 ubiquitin ligase, seven in absentia homolog 1 (Siah1), was recently identified in ocular tissues. In this article we examined the involvement of the GAPDH/Siah1 interaction in human retinal pericyte (hRP) apoptosis. HRP were cultured in 5 mm normal glucose, 25 mm l- or d-glucose for 48 h (osmotic control and high glucose treatments, respectively). Siah1 siRNA was used to down-regulate Siah1 expression. TAT-FLAG GAPDH and/or Siah1-directed peptides were used to block GAPDH and Siah1 interaction. Co-immunoprecipitation assays were conducted to analyze the effect of high glucose on the association of GAPDH and Siah1. Apoptosis was measured by Annexin V staining and caspase-3 enzymatic activity assay. High glucose increased Siah1 total protein levels, induced the association between GAPDH and Siah1, and led to GAPDH nuclear translocation. Our findings demonstrate that dissociation of the GAPDH/Siah1 pro-apoptotic complex can block high glucose-induced pericyte apoptosis, widely considered a hallmark feature of DR. Thus, the work presented in this article can provide a foundation to identify novel targets for early treatment of DR.

Metformin: A Novel but Controversial Drug in Cancer Prevention and Treatment

Metformin, a biguanide derivative that is widely used for treating type 2 diabetes mellitus, has recently been shown to exert potential anticancer effects. Many retrospective data and laboratory studies suggest the idea that metformin has antineoplastic activity, but some other studies reach conflicting conclusions. Although the precise molecular mechanisms by which metformin affects various cancers have not been fully elucidated, activation of AMPK-dependent and AMPK-independent pathways along with energy metabolism aberration, cell cycle arrest and apoptosis or autophagy induction have emerged as crucial regulators in this process. In this Review, we describe the role of metformin in the prevention and treatment of a variety of cancers and summarize the molecular mechanisms that are currently well documented in the ability of metformin as an anticancer agent. In addition, the scientific and clinical hurdles regarding the potential role of metformin in cancer will be discussed.

Effects of PPARγ agonistrosiglitazone on human retinoblastoma cell in vitro and in vivo

The aim of the study was to evaluate the antitumor effects of the PPARγ agonist rosiglitazone on the human retinoblastoma. The cell biological behavior was detected, specifically, the effects of rosiglitazone on cell viability and apoptosis of the human retinoblastoma Y79 cells were investigated by MTT assay and Hochest 33258 staining and the migration assay showed that rosiglitazone blocked the invasion and migration of the carcinoma cells through the reconstituted extracellular matrix (Matrigel). The effect of rosiglitazone on NF-κB-dependent reporter gene transcription induced by LPS was analyzed by NF-κB-luciferase assay. Then human retinoblastoma Y79 cells were subcutaneously transplanted in BALB/c nude mice, and the animals were treated with rosiglitazone (20 mg/kg, 40 mg/kg, and 80 mg/kg) to verify its anti-tumor effect in vivo. Rosiglitazone suppressed the viability of Y79 cells dose- and time-dependently and induced apoptosis in Y79 cells in vitro. Molecular biology analysis found that rosiglitazone could modulate the proliferative and apoptosis related signal, reduce NF-κB-dependent reporter gene transcription induced by LPS. Rosiglitazone markedly reduced the growth of Y79 cells transplanted into the mice without causing significant side effects. Our results suggested that rosiglitazone demonstrated antitumor activity against the human retinoblastoma Y79 cells by inhibiting cell growth, inducing apoptosis and inhibiting metastasis and invasion in vitro and delaying tumor growth in vivo.

Metformin inhibits the proliferation, metastasis, and cancer stem-like sphere formation in osteosarcoma MG63 cells in vitro

Metformin is an oral drug that has been widely used to treat type 2 diabetes mellitus. Interestingly, accumulated evidence indicate that metformin may reduce the risk of cancer in patients with type 2 diabetes and inhibit tumor cell growth and survival in numerous malignancies, including osteosarcoma (OS) cells. In the present study, we aimed to investigate the effects of metformin on the proliferation, migration, invasion, and sphere formation in OS MG63 cells in vitro. Metformin suppressed OS MG63 cell proliferation in a dose- and time-dependent manner and markedly blocked anti-metastatic potentials, migration, and invasion, by downregulating matrix metalloproteinase 2 (MMP2) and MMP9. Besides, we established OS cancer stem-like cell (CSC) model with sarcosphere formation assay and demonstrated that metformin posed damage on CSCs in OS by inhibiting sphere formation and by inducing their stemness loss. The stemness of CSCs in OS such as self-renewal and differentiation potentials was both impaired with a significant decrease of Oct-4 and Nanog activation. Consistent with this, the positive rates of CD90, CD133, and stage-specific embryonic antigen-4 (SSEA-4) were all observed with reductions in response to metformin exposure. In addition, Western blot showed that metformin activated AMPKα at Tyr172, followed by a downregulated phosphorylation of mammalian target of rapamycin (mTOR)/S6 and feedback activation of p-AKT Ser(473) in both OS MG63 cells and CSCs. This indicates that AMPK/mTOR/S6 signaling pathway might be involved in the growth inhibition of both OS MG63 cells and CSCs. These results suggest that metformin, a potential anti-neoplastic agent, might make it a novel therapeutic choice for the treatment of OS in the future.

Automated segmentation of geographic atrophy of the retinal epithelium via random forests in AREDS color fundus images

BACKGROUND

Age-related macular degeneration (AMD), left untreated, is the leading cause of vision loss in people older than 55. Severe central vision loss occurs in the advanced stage of the disease, characterized by either the in growth of choroidal neovascularization (CNV), termed the "wet" form, or by geographic atrophy (GA) of the retinal pigment epithelium (RPE) involving the center of the macula, termed the "dry" form. Tracking the change in GA area over time is important since it allows for the characterization of the effectiveness of GA treatments. Tracking GA evolution can be achieved by physicians performing manual delineation of GA area on retinal fundus images. However, manual GA delineation is time-consuming and subject to inter-and intra-observer variability.

METHODS

We have developed a fully automated GA segmentation algorithm in color fundus images that uses a supervised machine learning approach employing a random forest classifier. This algorithm is developed and tested using a dataset of images from the NIH-sponsored Age Related Eye Disease Study (AREDS). GA segmentation output was compared against a manual delineation by a retina specialist.

RESULTS

Using 143 color fundus images from 55 different patient eyes, our algorithm achieved PPV of 0.82±0.19, and NPV of 0:95±0.07.

DISCUSSION

This is the first study, to our knowledge, applying machine learning methods to GA segmentation on color fundus images and using AREDS imagery for testing. These preliminary results show promising evidence that machine learning methods may have utility in automated characterization of GA from color fundus images.

Enhanced GABA action on the substantia gelatinosa neurons of the medullary dorsal horn in the offspring of streptozotocin-injected mice

Peripheral neuropathy is a frequent complication of diabetes mellitus and a common symptom of neuropathic pain, the mechanism of which is complex and involves both peripheral and central components of the sensory system. The lamina II of the medullary dorsal horn, called the substantia gelatinosa (SG), is well known to be a critical site for processing of orofacial nociceptive information. Although there have been a number of studies done on diabetic neuropathy related to the orofacial region, the action of neurotransmitter receptors on SG neurons in the diabetic state is not yet fully understood. Therefore, we used the whole-cell patch clamp technique to investigate this alteration on SG neurons in both streptozotocin (STZ)-induced diabetic mice and offspring from diabetic female mice. STZ (200 mg/kg)-injected mice showed a small decrease in body weight and a significant increase in blood glucose level when compared with their respective control group. However, application of different concentrations of glycine, gamma-aminobutyric acid (GABA) and glutamate on SG neurons from STZ-injected mice did not induce any significant differences in inward currents when compared to their control counterparts. On the other hand, the offspring of diabetic female mice (induced by multiple injections of STZ (40 mg/kg) for 5 consecutive days) led to a significant decrease in both body weight and blood glucose level compared to the control offspring. Glycine and glutamate responses in the SG neurons of the offspring from diabetic female mice were similar to those of control offspring. However, the GABA response in SG neurons of offspring from diabetic female mice was greater than that of control offspring. Furthermore, the GABA-mediated responses in offspring from diabetic and control mice were examined at different concentrations ranging from 3 to 1,000 μM. At each concentration, the GABA-induced mean inward currents in the SG neurons of offspring from diabetic female mice were larger than those of control mice. These results demonstrate that SG neurons in offspring from diabetic mice are more sensitive to GABA compared to control mice, suggesting that GABA sensitivity may alter orofacial pain processing in offspring from diabetic female mice.