Moderate-Intensity Constant and High-Intensity Interval Training Confer Differential Metabolic Benefits in Skeletal Muscle, White Adipose Tissue, and Liver of Candidates to Undergo Bariatric Surgery.

Background/Objectives: Bariatric surgery candidates require presurgical physical training, therefore, we compared the metabolic effects of a constant moderate-intensity training program (MICT) vs. a high-intensity interval training (HIIT) in this population. Methods: Seventeen participants performed MICT (n = 9, intensity of 50% of heart rate reserve (HRR) and/or 4-5/10 subjective sensation of effort (SSE)) or HIIT (n = 8, 6 cycles of 2.5 min at 80% of the HRR and/or 7-8/10 of SSE, interspersed by 6 cycles of active rest at 20% of the FCR) for 10 sessions for 4 weeks. After training, tissue samples (skeletal muscle, adipose tissue, and liver) were extracted, and protein levels of adiponectin, GLUT4, PGC1α, phospho-AMPK/AMPK, collagen 1 and TGFß1 were measured. Results: Participants who performed MICT showed higher protein levels of PGC-1α in skeletal muscle samples (1.1 ± 0.27 vs. 0.7 ± 0.4-fold change, p < 0.05). In the liver samples of the people who performed HIIT, lower protein levels of phospho-AMPK/AMPK (1.0 ± 0.37 vs. 0.52 ± 0.22-fold change), PGC-1α (1.0 ± 0.18 vs. 0.69 ± 0.15-fold change), and collagen 1 (1.0 ± 0.26 vs. 0.59 ± 0.28-fold change) were observed (all p < 0.05). In subcutaneous adipose tissue, higher adiponectin levels were found only after HIIT training (1.1 ± 0.48 vs. 1.9 ± 0.69-fold change, p < 0.05). Conclusions: Our results show that both MICT and HIIT confer metabolic benefits in candidates undergoing bariatric surgery; however, most of these benefits have a program-specific fashion. Future studies should aim to elucidate the mechanisms behind these differences.

Moderate-intensity constant or high-intensity interval training? Metabolic effects on candidates to undergo bariatric surgery.

BACKGROUND & AIMS: Bariatric surgery is highly effective against obesity. Pre-surgical exercise programs are recommended to prepare the candidate physically and metabolically for surgery-related rapid weight loss. However, the ideal exercise prescription in this population is unknown. This study aimed to compare the metabolic effects of moderate-intensity constant (MICT) vs. a high-intensity interval training (HIIT) program in candidates to undergo bariatric surgery. METHODS AND RESULTS: Twenty-five candidates (22 women) to undergo sleeve gastrectomy aged from 18 to 60 years old were recruited. At baseline, we measured body composition, physical activity levels, grip strength, and aerobic capacity. Further, we assessed metabolic function through glycemia and insulinemia (both fasting and after oral glucose tolerance test (OGTT)), homeostatic model assessment for insulin resistance (HOMA-IR), lipid profile, glycated haemoglobin (HbA1c), transaminases, fibroblast growth factor 21 (FGF21), growth differentiation factor 15 (GDF15), apelin, and adiponectin. Afterward, participants were randomized into MICT (n = 14) or HIIT (n = 11). Both training programs consisted of 10 sessions (2-3 times/week, 30 min per session) distributed during 4 weeks before the surgery. After this, all outcomes were measured again at the end of the training programs and 1 month after the surgery (follow-up). A mixed effect with Tukey's post-hoc analysis was performed to compare values at baseline vs. post-training vs. postsurgical follow-up. Both training programs increased aerobic capacity after training (p < 0.05), but only after MICT these changes were kept at follow-up (p < 0.05). However, only MICT decreased fat mass and increased total muscle mass and physical activity levels (p < 0.05). Metabolically, MICT decreased insulinemia after OGTT (p < 0.05), whereas HIIT increased adiponectin after training and GDF15 at follow-up (both p < 0.05). CONCLUSIONS: Both MICT and HIIT conferred benefits in candidates to undergo bariatric surgery, however, several of those effects were program-specific, suggesting that exercise intensity should be considered when preparing these patients. Future studies should explore the potential benefits of prescribing MICT or HIIT in a customized fashion depending on a pretraining screening, along with possible summatory effects by combining these two exercise programs (MICT + HIIT). CLINICAL TRIAL REGISTRATION: International Traditional Medicine Clinical Trial Registry, N° ISRCTN42273422.

Respuesta fisiológica al test de lanzadera en pacientes candidatos a cirugía bariátrica / Physiologic response to the incremental shuttle walk test in candidates to undergo bariatric surgery / Resposta fisiológica ao teste incremental de caminhada em candidatos a cirurgia bariátrica

Objetivos: la valoración de la tolerancia al ejercicio es clave para prescribir ejercicio en candidatos a cirugía bariátrica. El test de lanzadera (TL) se ha propuesto para este objetivo. Sin embargo, la evidencia que describe el rendimiento y respuesta fisiológica asociados a esta prueba en dicha población es escasa. El objetivo de este estudio fue describir la respuesta fisiológica a la realización del TL en candidatos a cirugía bariátrica. Métodos: este estudio transversal incluyó a 56 participantes. Se midieron factores antropométricos como la edad, peso, estatura y circunferencia de cintura, así como el nivel de actividad física espontáneo. Se valoró el rendimiento en el TL en metros, la respuesta fisiológica asociada en términos de frecuencia cardiaca de reserva (FCR) utilizada, presión arterial sistólica y diastólica, oximetría de pulso, sensación subjetiva al esfuerzo (SSE) y de fatiga de extremidades inferiores, antes y después del TL. Resultados: todos los participantes completaron la prueba sin complicaciones. Caminaron una mediana de 465 metros, equivalente al 61% de la distancia esperada. Utilizaron un 56% de la FCR, mientras que la SSE y fatiga de extremidades inferiores alcanzó valores 7/10 y 6/10 respectivamente. Fueron observadas asociaciones significativas entre el rendimiento en el TL vs factores antropométricos e indicadores de respuesta fisiológica. Conclusión: el TL es una prueba segura para valorar la tolerancia al esfuerzo en candidatos a cirugía bariátrica, la cual induce respuestas fisiológicas asociadas a intensidades moderadas. Se sugiere incluir esta prueba para la valoración de la condición física de estos sujetos.

Objective: Exercise tolerance measurement is key for exercise prescription in bariatric surgery candidates. Thus, the incremental shuttle walking test (ISWT) has been proposed as a useful tool for this purpose. However, reports describing the performance, and related physiological response, in candidates to bariatric surgery are scarce. Therefore, the aim of this study was to describe the physiological response of bariatric surgery candidates to the ISWT. Methods: This cross-sectional study included 56 participants. Anthropometric factors such as age, weight, height, and waist circumference were measured, as well as their spontaneous physical activity levels. Their ISWT performance was recorded, as well as the percentage of heart rate reserve used during the test, systolic and diastolic pressure, pulse oximetry, perceived exertion scale, and lower extremities fatigue, both before and after the ISWT. Results: All participants completed the test without complications. They walked a median of 465 meters, 61% of the expected distance. Heart rate reserve utilization reached 56%, while the perceived exertion rate and lower extremities fatigue reached 7/10 and 6/10, respectively. Moreover, significant associations between the ISWT performance vs anthropometric factors and physiological response outcomes were found. Conclusion: The ISWT is a safe and useful tool to assess exercise tolerance in bariatric surgery candidates, which induces physiological responses associated to moderate effort intensities. We suggest including the ISWT when assessing the physical performance of bariatric surgery candidates.

Objetivo: A medida da tolerância ao exercício é fundamental para a prescrição do exercício em candidatos à cirurgia bariátrica. Assim, o teste incremental de caminhada em vaivém (ISWT) tem sido proposto como uma ferramenta útil para este fim. No entanto, são escassos os relatos que descrevem o desempenho e a resposta fisiológica relacionada em candidatos à cirurgia bariátrica. Portanto, o objetivo deste estudo foi describir a resposta fisiológica do ISWT em candidatos à cirurgia bariátrica. Métodos: Este estudo transversal incluiu 56 participantes. Fatores antropométricos como idade, peso, altura, circunferência da cintura foram medidos, assim como os níveis de atividade física espontânea. O desempenho do ISWT foi registrado, assim como a porcentagem de reserva de frequência cardíaca utilizada durante o teste, pressão sistólica e diastólica, oximetria de pulso, escala de esforço percebido e fadiga de membros inferiores, tanto antes quanto após o ISWT. Resultados: Todos os participantes completaram o teste sem intercorrências. Eles caminharam uma mediana de 465 metros, o equivalente a 61% da distância esperada. A utilização de reserva de frequência cardíaca atingiu 56%, enquanto a taxa de esforço percebido e fadiga de membros inferiores atingiram 7/10 e 6/10, respectivamente. Além disso, foram encontradas associações significativas entre o desempenho do ISWT versus fatores antropométricos e os resultados da resposta fisiológica. Conclusão: O ISWT é uma ferramenta segura e útil para avaliar a tolerância ao exercício em candidatos à cirurgia bariátrica, que induz respostas fisiológicas associadas a intensidades moderadas de esforço. Sugerimos incluir o ISWT para avaliar o desempenho físico dos candidatos à cirurgia bariátrica.

Insects as alternative feed for ruminants: comparison of protein evaluation methods.

BACKGROUND: The high dependence of intensive ruminant production on soybean meal and the environmental impact of this crop encourage the search for alternative protein-rich feeds. The use of insects seems promising, but the extent of their ruminal protein degradation is largely unknown. This parameter has major influence not only on N utilization efficiency but also on the environmental burden of ruminant farming. In addition, although assessing ruminal N degradation represents a key first step to examine the potential of new feeds, it is a challenging task due to the lack of a reference method. This study was conducted to investigate the potential of 4 insects (Tenebrio molitor, Zophobas morio, Alphitobius diaperinus and Acheta domesticus) as alternative protein sources for ruminants, using 3 methodologies: 1) a regression technique based on the in vitro relationship between gas production and ammonia-N concentration; 2) a conventional in vitro technique of batch cultures of ruminal microorganisms, based on filtering the incubation residue through sintered glass crucibles; and 3) the in situ nylon bag technique. The in vitro intestinal digestibility of the non-degraded protein in the rumen was also determined. Soybean meal was used as a reference feedstuff. RESULTS: Comparison of evaluation methods (regression, in vitro and in situ) did not allow to reliably select a single value of ruminal N degradation for the studied substrates, but all techniques seem to establish a similar ranking, with good correlations between methods, particularly between regression and in situ results. Regardless of the methodology, nitrogen from the 4 insects (with contents ranging from 81 to 112 g/kg of dry matter) did not show high ruminal degradation (41-76%), this value being always lower than that of soybean meal. Furthermore, the in vitro intestinal digestibility of non-degraded N was relatively high in all feeds (≥ 64%). CONCLUSION: Overall, these results support the potential of the 4 studied insects as alternative feedstuffs for ruminants. Among them, T. molitor showed the lowest and greatest values of ruminal N degradation and intestinal digestibility, respectively, which would place it as probably the best option to replace dietary soybean meal and increase the sustainability of ruminant feeding.

Demographic/anthropometric factors and physiological performance-related parameters associated with the six-minute walk test in bariatric surgery candidates, from Valdivia, Chile / Fatores demográficos/antropométricos e parâmetros fisiológicos relacionados ao desempenho associados ao teste de caminhada de seis minutos em candidatos à cirurgia bariátrica, de Valdivia, Chile / Factores demográficos/antropométricos y parámetros fisiológicos relacionados con el desempeño en la prueba de la marcha de seis minutos de candidatos a cirugía bariátrica de Valdivia, Chile

ABSTRACT The six-minute walk test (6MWT) is widely used to measure functional capacity in special populations. However, the factors associated with its performance in candidates for bariatric surgery are unclear. Therefore, this study aimed to investigate the influence of anthropometric and physiological factors in the 6MWT performance in bariatric surgery candidates. This cross-sectional study included 107 candidates for bariatric surgery. Anthropometric factors considered: gender, weight, height, body mass index (BMI), waist-to-hip, and waist-to-height ratios. Along with distance covered during 6MWT, physiological factors such as ratings of perceived exertion (RPE) and heart rate reserve percentage used (%HRR) were recorded. Among the 107 patients (mean age: 39.6 years), 83 volunteers were accepted to perform the 6MWT. No gender differences were observed in terms of distance covered, %HRR, and RPE during the 6MWT. Moreover, BMI and %HRR explained 21% of the 6MWT distance covered. Furthermore, participants with BMI ≤41.5 kg/m2 walked ~50 meters more than their peers above this level (p=0.05). Interestingly, heart rate increase during the 6MWT was lower than described for healthy populations. BMI and %HRR partially explain the variability of the 6MWT performance in bariatric surgery candidates.

RESUMO O teste de caminhada de seis minutos (TC6) é uma ferramenta amplamente usada para medir a capacidade funcional em populações especiais. No entanto, os fatores associados ao seu desempenho em candidatos à cirurgia bariátrica não são claros. Portanto, o objetivo deste estudo foi investigar a influência de fatores antropométricos e fisiológicos no desempenho do TC6 em candidatos à cirurgia bariátrica. Este estudo transversal incluiu 107 candidatos à cirurgia bariátrica. Os fatores antropométricos incluíram: sexo, peso, altura, índice de massa corporal (IMC) e índices cintura-quadril e altura-cintura. Além da distância percorrida durante o TC6, foram registrados fatores fisiológicos, como sensação subjetiva de esforço (SSE) e a porcentagem de frequência cardíaca de reserva utilizada (% FCR). Dos 107 pacientes (idade média: 39,6 anos), 83 voluntários concordaram em realizar o TC6. Não foram observadas diferenças por sexo em termos de distância percorrida, % FCR e SSE durante o TC6. Além disso, IMC e% FCR explicaram 21% da distância percorrida no TM6M. Além disso, indivíduos com IMC≤41,5 kg/m2 andaram ~50 metros a mais do que seus pares acima desse nível (p=0,05). Curiosamente, os aumentos na frequência cardíaca durante o TC6 foram inferiores aos descritos em populações saudáveis. IMC e %FCR foram fatores que explicaram parte da variabilidade do desempenho da TC6 em candidatos submetidos à cirurgia bariátrica.

RESUMEN La prueba de la marcha de seis minutos (PM6) es una herramienta muy utilizada para medir la capacidad funcional en ciertas poblaciones. Sin embargo, poco se conoce sobre los factores asociados a su desempeño en candidatos a cirugía bariátrica. Ante esto, el objetivo de este estudio fue evaluar la influencia de factores antropométricos y fisiológicos en el desempeño de la PM6 en candidatos a cirugía bariátrica. En este estudio transversal participaron 107 candidatos a cirugía bariátrica. Los factores antropométricos fueron: sexo, peso, altura, índice de masa corporal (IMC) e índices cintura-cadera y altura-cintura. Además de la distancia recorrida durante la PM6, se registraron los factores fisiológicos como la sensación subjetiva de esfuerzo (SSE) y el porcentaje de frecuencia cardíaca de reserva utilizada (% FCR). De los 107 pacientes (edad media: 39,6 años), 83 voluntarios aceptaron realizar la PM6. No se encontraron diferencias por sexo respecto de la distancia recorrida, % FCR y ESS durante la PM6. Además, el IMC y el % FCR explicaron el 21% de la distancia recorrida en la PM6. Y los individuos con un IMC ≤41,5 kg/m2 caminaron ~50 metros más que sus pares por encima de este nivel (p=0,05). Resultó interesante que el incremento de la frecuencia cardíaca durante la PM6 fue más bajo que los reportados en poblaciones sanas. El IMC y % FCR fueron los factores que explicaron parte de la variabilidad en el desempeño de la PM6 en candidatos a cirugía bariátrica.

Coexistence of Fragile-X Syndrome, 8p23.1 Deletion, and Balanced Translocation t(7;10)(p10;q24) in a Single Family.

Aims: Fragile-X syndrome (FXS) is the most common inherited form of intellectual disability; it is caused by an abnormal CGG-repeat expansion at the FMR1 gene. However, a few cases of girls with mutations in the FMR1 gene have been reported in the literature. In this study, we describe the clinical and genetic assessment of a family who exhibits the unusual coexistence of FXS, an 8p23.1 deletion, and balanced translocation t(7;10)(p10;q24) in multiple members, including a symptomatic girl with FXS. Materials and Methods: All of the family members underwent comprehensive clinical and neurological examinations. All members of the family were also molecularly diagnosed using a combination of fluorescent-polymerase chain reaction (PCR), Triplet Repeat Primed-PCR, capillary electrophoresis, and karyotyping. Results: We identified a male proband and a female patient that presented with the craniofacial characteristics of FXS, neuropsychomotor developmental delay, speech delay, intellectual deficit, and a positive molecular diagnosis of FXS. Interestingly, the female patient presented with a severe phenotype also associated with the presence of 8p23.1 deletion, while the proband patient presented a balanced translocation t(7;10)(p10;q24). Moreover, we detected multiple carriers of the FXS premutation in the family. Conclusions: To our knowledge, we describe for the first time the simultaneous occurrence of FXS and an 8p23.1 deletion and their possible synergistic effects on the phenotype of a female patient. Moreover, we describe the coexistence of FXS, an 8p23.1 deletion, and a balanced translocation t(7;10)(p10;q24) in the same family.

Loss of PGC-1α in RPE induces mesenchymal transition and promotes retinal degeneration.

The retinal pigment epithelium (RPE) supports visual processing and photoreceptor homeostasis via energetically demanding cellular functions. Here, we describe the consequences of repressing peroxisome proliferator-activated receptor γ coactivator-1 α (PGC-1α), a master regulator of mitochondrial function and biogenesis, on RPE epithelial integrity. The sustained silencing of PGC-1α in differentiating human RPE cells affected mitochondria/autophagy function, redox state, and impaired energy sensor activity ultimately inducing epithelial to mesenchymal transition (EMT). Adult conditional knockout of PGC-1 coactivators in mice resulted in rapid RPE dysfunction and transdifferentiation associated with severe photoreceptor degeneration. RPE anomalies were characteristic of autophagic defect and mesenchymal transition comparable with the ones observed in age-related macular degeneration. These findings demonstrate that PGC-1α is required to maintain the functional and phenotypic status of RPE by supporting the cells' oxidative metabolism and autophagy-mediated repression of EMT.

Can Children Have Ordinary Expectable Caregiving Environments in Unconventional Contexts? Quality of Care Organization in Three Mexican Same-Sex Planned Families.

The aim of this research was to explore the elements that configure the quality of care among three Mexican same-sex planned families: two female-parented families (through donor insemination) and a male-parented one (through adoption). The first family consisted of two mothers and a 3-year-old daughter; the second one had two mothers and a 1.5-year-old set of boy twins and the third family consisted of two fathers and a 2-year-old girl. It was assumed that Ainsworth's notions of quality of care organization are useful in order to understand caregiver-child attachment relationships, regardless of the parents' sexual orientation. A collective case study was selected due to the fact that these families shared their "unconventionality" (i.e., parents were not heterosexual) and the fact that they were planned, but each one constituted a particular case with a unique configuration. Four trained independent observers used the q-sort methodology (Maternal Behavior Q-Sort and Attachment Q-Sort) to describe parents' and children's behavior, respectively. The findings showed that parents were highly sensitive and all children used them as a secure base. To provide an in-depth examination of which elements configure the quality of care, a semi-structured interview with each parent was carried out. Through a thematic analysis, an over-arching theme named Affections and Emotions was identified, together with six subthemes: (1) Creating an affective environment; (2) Being available; (3) Acknowledging and expressing emotions; (4) Perceiving, interpreting and responding adequately to the child's real self; (5) Taking the child's perspective into account; and (6) Agreeing on roles and dividing the tasks. In order to showcase the particular configuration of gay parenting, the male-headed family narrative is reported in detail, because gay parents have been perceived as violating traditional gender roles as well as the hegemonic model of masculinity. The findings were consistent with the notion of quality of care as proposed by Ainsworth and her collaborators. The implications of the methodological device and research regarding same-sex planned families are discussed so as to understand the organization of the caregiving environment.

Pharmaceutical Induction of PGC-1α Promotes Retinal Pigment Epithelial Cell Metabolism and Protects against Oxidative Damage.

Retinal pigment epithelium (RPE) dysfunction due to accumulation of reactive oxygen species and oxidative damage is a key event in the development of age-related macular degeneration (AMD). Here, we examine the therapeutic potential of ZLN005, a selective PGC-1α transcriptional regulator, in protecting RPE from cytotoxic oxidative damage. Gene expression analysis on ARPE-19 cells treated with ZLN005 shows robust upregulation of PGC-1α and its associated transcription factors, antioxidant enzymes, and mitochondrial genes. Energetic profiling shows that ZLN005 treatment enhances RPE mitochondrial function by increasing basal and maximal respiration rates, and spare respiratory capacity. In addition, ZLN005 robustly protects ARPE-19 cells from cell death caused by H2O2, ox-LDL, and NaIO3 without exhibiting any cytotoxicity under basal conditions. ZLN005 protection against H2O2-mediated cell death was lost in PGC-1α-silenced cells. Our data indicates that ZLN005 efficiently protects RPE cells from oxidative damage through selective induction of PGC-1α and its target antioxidant enzymes. ZLN005 may serve as a novel therapeutic agent for retinal diseases associated with RPE dystrophies.

Eyeing the Fountain of Youth.

Stem cell-based disease modeling is an emerging technology for the mechanistic study and therapeutic screening of complex ocular pathologies. In this issue of Cell Stem Cell, Saini et al. (2017) show that iPSC-derived RPE cells from age-related macular degeneration patients express increased levels of pro-inflammatory factors that can be normalized by the anti-aging drug nicotinamide.

Conditioned Medium from Early-Outgrowth Bone Marrow Cells Is Retinal Protective in Experimental Model of Diabetes.

Bone marrow-derived cells were demonstrated to improve organ function, but the lack of cell retention within injured organs suggests that the protective effects are due to factors released by the cells. Herein, we tested cell therapy using early outgrowth cells (EOCs) or their conditioned media (CM) to protect the retina of diabetic animal models (type 1 and type 2) and assessed the mechanisms by in vitro study. Control and diabetic (db/db) mice (8 weeks of age) were randomized to receive a unique intravenous injection of 5×105EOCs or 0.25 ml thrice weekly tail-vein injections of 10x concentrated CM and Wystar Kyoto rats rendered diabetic were randomized to receive 0.50 ml thrice weekly tail-vein injections of 10x concentrated CM. Four weeks later, the animals were euthanized and the eyes were enucleated. Rat retinal Müller cells (rMCs) were exposed for 24 h to high glucose (HG), combined or not with EOC-conditioned medium (EOC-CM) from db/m EOC cultures. Diabetic animals showed increase in diabetic retinopathy (DR) and oxidative damage markers; the treatment with EOCs or CM infusions significantly reduced this damage and re-established the retinal function. In rMCs exposed to diabetic milieu conditions (HG), the presence of EOC-CM reduced reactive oxygen species production by modulating the NADPH-oxidase 4 system, thus upregulating SIRT1 activity and deacetylating Lys-310-p65-NFκB, decreasing GFAP and VEGF expressions. The antioxidant capacity of EOC-CM led to the prevention of carbonylation and nitrosylation posttranslational modifications on the SIRT1 molecule, preserving its activity. The pivotal role of SIRT1 on the mode of action of EOCs or their CM was also demonstrated on diabetic retina. These findings suggest that EOCs are effective as a form of systemic delivery for preventing the early molecular markers of DR and its conditioned medium is equally protective revealing a novel possibility for cell-free therapy for the treatment of DR.

Polyphenol-enriched cocoa protects the diabetic retina from glial reaction through the sirtuin pathway.

Cocoa is rich in flavonoids, which are potent antioxidants with established benefits for cardiovascular health but unproven effects on neurodegeneration. Sirtuins (SIRTs), which make up a family of deacetylases, are thought to be sensitive to oxidation. In this study, the possible protective effects of cocoa in the diabetic retina were assessed. Rat Müller cells (rMCs) exposed to normal or high glucose (HG) or H2O2 were submitted to cocoa treatment in the presence or absence of SIRT-1 inhibitor and small interfering RNA The experimental animal study was conducted in streptozotocin-induced diabetic rats randomized to receive low-, intermediate-, or high-polyphenol cocoa treatments via daily gavage for 16 weeks (i.e., 0.12, 2.9 or 22.9 mg/kg/day of polyphenols). The rMCs exposed to HG or H2O2 exhibited increased glial fibrillary acidic protein (GFAP) and acetyl-RelA/p65 and decreased SIRT1 activity/expression. These effects were cancelled out by cocoa, which decreased reactive oxygen species production and PARP-1 activity, augmented the intracellular pool of NAD(+), and improved SIRT1 activity. The rat diabetic retinas displayed the early markers of retinopathy accompanied by markedly impaired electroretinogram. The presence of diabetes activated PARP-1 and lowered NAD(+) levels, resulting in SIRT1 impairment. This augmented acetyl RelA/p65 had the effect of up-regulated GFAP. Oral administration of polyphenol cocoa restored the above alterations in a dose-dependent manner. This study reveals that cocoa enriched with polyphenol improves the retinal SIRT-1 pathway, thereby protecting the retina from diabetic milieu insult.

Endocytosis of tight junctions caveolin nitrosylation dependent is improved by cocoa via opioid receptor on RPE cells in diabetic conditions.

PURPOSE: Retinal pigment epithelium cells, along with tight junction (TJ) proteins, constitute the outer blood retinal barrier (BRB). Contradictory findings suggest a role for the outer BRB in the pathogenesis of diabetic retinopathy (DR). The aim of this study was to investigate whether the mechanisms involved in these alterations are sensitive to nitrosative stress, and if cocoa or epicatechin (EC) protects from this damage under diabetic (DM) milieu conditions. METHODS: Cells of a human RPE line (ARPE-19) were exposed to high-glucose (HG) conditions for 24 hours in the presence or absence of cocoa powder containing 0.5% or 60.5% polyphenol (low-polyphenol cocoa [LPC] and high-polyphenol cocoa [HPC], respectively). RESULTS: Exposure to HG decreased claudin-1 and occludin TJ expressions and increased extracellular matrix accumulation (ECM), whereas levels of TNF-α and inducible nitric oxide synthase (iNOS) were upregulated, accompanied by increased nitric oxide levels. This nitrosative stress resulted in S-nitrosylation of caveolin-1 (CAV-1), which in turn increased CAV-1 traffic and its interactions with claudin-1 and occludin. This cascade was inhibited by treatment with HPC or EC through δ-opioid receptor (DOR) binding and stimulation, thereby decreasing TNF-α-induced iNOS upregulation and CAV-1 endocytosis. The TJ functions were restored, leading to prevention of paracellular permeability, restoration of resistance of the ARPE-19 monolayer, and decreased ECM accumulation. CONCLUSIONS: The detrimental effects on TJs in ARPE-19 cells exposed to DM milieu occur through a CAV-1 S-nitrosylation-dependent endocytosis mechanism. High-polyphenol cocoa or EC exerts protective effects through DOR stimulation.

S-nitrosoglutathione inhibits inducible nitric oxide synthase upregulation by redox posttranslational modification in experimental diabetic retinopathy.

PURPOSE: Diabetic retinopathy (DR) is associated with nitrosative stress. The purpose of this study was to evaluate the beneficial effects of S-nitrosoglutathione (GSNO) eye drop treatment on an experimental model of DR. METHODS: Diabetes (DM) was induced in spontaneously hypertensive rats (SHR). Treated animals received GSNO eye drop (900 nM or 10 µM) twice daily in both eyes for 20 days. The mechanisms of GSNO effects were evaluated in human RPE cell line (ARPE-19). RESULTS: In animals with DM, GSNO decreased inducible nitric oxide synthase (iNOS) expression and prevented tyrosine nitration formation, ameliorating glial dysfunction measured with glial fibrillary acidic protein, resulting in improved retinal function. In contrast, in nondiabetic animals, GSNO induced oxidative/nitrosative stress in tissue resulting in impaired retinal function. Nitrosative stress was present markedly in the RPE layer accompanied by c-wave dysfunction. In vitro study showed that treatment with GSNO under high glucose condition counteracted nitrosative stress due to iNOS downregulation by S-glutathionylation, and not by prevention of decreased GSNO and reduced glutathione levels. This posttranslational modification probably was promoted by the release of oxidized glutathione through GSNO denitrosylation via GSNO-R. In contrast, in the normal glucose condition, GSNO treatment promoted nitrosative stress by NO formation. CONCLUSIONS: In this study, a new therapeutic modality (GSNO eye drop) targeting nitrosative stress by redox posttranslational modification of iNOS was efficient against early damage in the retina due to experimental DR. The present work showed the potential clinical implications of balancing the S-nitrosoglutathione/glutathione system in treating DR.

Green tea is neuroprotective in diabetic retinopathy.

PURPOSE: Green tea (GT), widely studied for its beneficial properties in protecting against brain ischemia, is a rich source of polyphenols, particularly (-)-epigallocatechin gallate (EGCG). The results presented here demonstrate the beneficial effects of GT in diabetic retinas and in retinal cells under diabetic conditions. METHODS: Diabetes was induced in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats. Treatment animals received GT orally for 12 weeks. A vehicle was administered orally to the control animals. The protective effects of GT were also evaluated in Müller and in ARPE-19 cells. RESULTS: In diabetic rats, there was an increase in the expression of glial fibrillary acidic protein (GFAP), oxidative retinal markers, and glutamine synthetase levels. In addition, there was a decrease in occludin and glutamate transporter and receptor. Diabetic SHR also demonstrated blood-retinal barrier breakdown and impaired electroretinography results. Müller cells exposed to high-glucose medium produced higher levels of reactive oxygen species (ROS) and glutamine synthetase but reduced levels of glutathione, glutamate transporter, and glutamate receptor. Similarly, ARPE-19 cells exhibited increased ROS production accompanied by decreased expression of claudin-1 and glutamate transporter. Treatment with GT fully restored all the above-mentioned alterations in diabetic animals as well as in retinal cells. CONCLUSIONS: GT protected the retina against glutamate toxicity via an antioxidant mechanism. These findings reveal a novel mechanism by which GT protects the retina against neurodegeneration in disorders such as diabetic retinopathy.

The concomitance of hypertension and diabetes exacerbating retinopathy: the role of inflammation and oxidative stress.

Diabetes and hypertension frequently coexist and constitute the most notorious combination for the pathogenesis of DR. Large clinical trials have clearly demonstrated that tight control of glycaemia and/or blood pressure significantly reduces the incidence and progression of DR. The mechanism by which hypertension interacts with diabetes to exacerbate the retinal disease is not completely understood. From experimental studies, increasing evidence demonstrates that chronic inflammation and oxidative stress are involved. In the present review, we summarize data obtained from our research along with those from other groups to better understand the role of hypertension in the pathogenesis of DR. It is suggested that oxidative stress and inflammation may be common denominators of retinal damage in the presence of hypertension in diabetic patients.

Reduction of inducible nitric oxide synthase via angiotensin receptor blocker prevents the oxidative retinal damage in diabetic hypertensive rats.

PURPOSE: To investigate if nitric oxide (NO) system contributes to the beneficial effect of angiotensin II type 1 receptor (AT(1)) blocker losartan in the retina of diabetic spontaneously hypertensive rats (SHR). METHODS: Diabetic SHR were randomized to receive oral treatment with losartan (DM-SHRLos). After 20 days, the rats were euthanized and the retinas collected. RESULTS: Diabetic SHR rats exhibited a significant increase in glial fibrillary acidic protein (GFAP) and decrease in occludin, markers of early diabetic retinopathy (DR). The oxidative status, evaluated by NO end-products (NO(x)(-)) levels along with the antioxidative system superoxide dismutase, revealed an accentuated imbalance in favor to oxidants in DM-SHR leading to a higher tyrosine nitration and DNA damage. The inducible NO synthase (iNOS) was also elevated in DM-SHR rats. The treatment with losartan ameliorated all of the above alterations. CONCLUSIONS: Oral treatment with losartan reduces iNOS expression and reestablishes the redox status, thus ameliorating the early markers of DR in a model of diabetes and hypertension.

Exogenous SOD mimetic tempol ameliorates the early retinal changes reestablishing the redox status in diabetic hypertensive rats.

PURPOSE: The purpose of this study was to investigate the efficacy of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), a superoxide dismutase mimetic, in preventing early retinal molecular changes in a model that combines hypertension and diabetes. METHODS: Four-week-old spontaneously hypertensive rats (SHR) were rendered diabetic by streptozotocin. Diabetic SHR rats (DM-SHR) were randomized to receive or not receive tempol treatment. After 20 days of induction of diabetes, the rats were euthanatized, and their retinas were collected. RESULTS: The early molecular markers of diabetic retinopathy (DR), glial fibrillary acidic protein, and fibronectin were evaluated by Western blot assays and showed an increase in DM-SHR compared with the SHR group. The oxidative balance, evaluated by superoxide production and nitric oxide end product levels estimated by a nitric oxide analyzer, and the counterpart antioxidative defense revealed an accentuated imbalance in DM-SHR compared with the SHR group. As a result, the product peroxynitrite, which was detected by immunohistochemistry for nitrotyrosine, was higher in the DM-SHR group. The retinal poly-ADP-ribose (PAR)-modified proteins, which reflect the activation of PAR polymerase (PARP), and the inducible nitric oxide synthase (iNOS) expressions were found to have increased in this group. Treatment with tempol reestablished the oxidative parameters and decreased the PAR-modified proteins, thus preventing extracellular matrix accumulation and glial reaction. CONCLUSIONS: The administration of tempol prevented oxidative damage, decreased iNOS levels, and ameliorated the activation of PARP in the retinas of diabetic hypertensive rats. Consequently, the early molecular markers of DR, such as glial reaction (glial fibrillary acidic protein [GFAP]) and extracellular matrix accumulation (fibronectin), were prevented in tempol-treated rats.

Diabetic retinal neurodegeneration is associated with mitochondrial oxidative stress and is improved by an angiotensin receptor blocker in a model combining hypertension and diabetes.

OBJECTIVE: Diabetic retinopathy displays the features of a neurodegenerative disease. Oxidative stress is involved in the pathogenesis of diabetic retinopathy. This investigation sought to determine whether hypertension exacerbates the oxidative stress, neurodegeneration, and mitochondrial dysfunction that exists in diabetic retinopathy and whether these changes could be minimized by the angiotensin II type 1 (AT(1)) receptor blocker (ARB) losartan. RESEARCH DESIGN AND METHODS: Diabetes was induced in spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. The diabetic SHRs were assigned to receive or not receive losartan. RESULTS: The level of apoptosis in the retina was higher in diabetic WKY rats than in the control group, and higher levels were found in diabetic SHRs. The apoptotic cells expressed neural and glial markers. The retinal glial reaction was more evident in diabetic WKY rats and was markedly accentuated in diabetic SHRs. Superoxide production in retinal tissue increased in diabetic WKY rats, and a greater increase occurred in diabetic SHRs. Glutathione levels decreased only in diabetic SHRs. As a consequence, the levels of nitrotyrosine and 8-hydroxy 2'-deoxyguanosine, markers of oxidative stress, were elevated in diabetic groups, mainly in diabetic SHRs. Mitochondrial integrity was dramatically affected in the diabetic groups. The ARB treatment reestablished all of the above-mentioned parameters. CONCLUSIONS: These findings suggest that concomitance of hypertension and diabetes exacerbates oxidative stress, neurodegeneration, and mitochondrial dysfunction in the retinal cells. These data provide the first evidence of AT(1)blockage as a neuroprotective treatment of diabetic retinopathy by reestablishing oxidative redox and the mitochondrial function.