Diabetic Retinopathy and Skin Tissue Advanced Glycation End Products Are Biomarkers of Cardiovascular Events in Type 2 Diabetic Patients.

Risk of cardiovascular events is not homogeneous in subjects with type 2 diabetes; therefore, its early identification remains a challenge to be met. The aim of this study is to evaluate whether the presence of diabetic retinopathy and accumulation of advanced glycation end-products in subcutaneous tissue can help identify patients at high risk of cardiovascular events. For this purpose, we conducted a prospective study (mean follow-up: 4.35 years) comprising 200 subjects with type 2 diabetes with no history of clinical cardiovascular disease and 60 non-diabetic controls matched by age and sex. The primary outcome was defined as the composite of myocardial infarction, coronary revascularization, stroke, lower limb amputation or cardiovascular death. The Cox proportional hazard multiple regression analysis was used to determine the independent predictors of cardiovascular events. The patients with type 2 diabetes had significantly more cardiovascular events than the non-diabetic subjects. Apart from the classic factors such as age, sex and coronary artery calcium score, we observed that the diabetic retinopathy and advanced glycation end-products in subcutaneous tissue were independent predictors of cardiovascular events. We conclude that the diabetic retinopathy and advanced glycation end-products in subcutaneous tissue could be useful biomarkers for selecting type 2 diabetic patients in whom the screening for cardiovascular disease should be prioritized, thereby creating more personalized and cost-effective medicine.

Detection of Viruses and Virus-Neutralizing Antibodies Using Synthetic Erythrocytes: Toward a Tuneable Tool for Virus Surveillance.

The hemagglutination inhibition assay (HAI) is a classical method used worldwide in many analytical applications, including pathogen identification, vaccine production monitoring, and detection and characterization of pathogen-neutralizing antibodies (n-Ab). This is also a World Health Organization (WHO) reference method for the global surveillance of influenza viruses, which provides the information needed for the annual reformulation of the flu vaccine. HAI is a simple and inexpensive method that is performed without sophisticated equipment. However, it has to be carried out with fresh red blood cells (RBCs), a highly variable, unstable, and hard to mass-produce reagent, which impairs assay reproducibility. Here, we used the tests employed for influenza surveillance as a model to develop synthrocytes©, a synthetic reagent that could substitute animal erythrocytes in HAI. Contrary to previous examples exploiting sophisticated production paths to generate therapeutic synthetic RBCs, we founded production on the identification of microparticles able to generate different sedimentation patterns when agglutinated or not, which is the main requirement for HAI testing. Upon incorporation of influenza-binding receptors and optimization of production and assay conditions, synthrocytes succeeded in binding influenza A(H1N1) and B viruses as erythrocytes do, but were faster and more stable. Synthrocytes were finally employed in an HAI-like assay to detect the WHO reference reagents for influenza surveillance. Our results show that it is possible to substitute erythrocytes in classical HAI by a highly tuneable and potentially mass-produced synthetic reagent, which should facilitate worldwide HAI standardization with minimal equipment or training requirements.

The mitochondrial antioxidant SS-31 increases SIRT1 levels and ameliorates inflammation, oxidative stress and leukocyte-endothelium interactions in type 2 diabetes.

There is growing focus on mitochondrial impairment and cardiovascular diseases (CVD) in type 2 diabetes (T2D), and the development of novel therapeutic strategies in this context. It is unknown whether mitochondrial-targeting antioxidants such as SS-31 protect sufficiently against oxidative damage in diabetes. We aimed to evaluate if SS-31 modulates SIRT1 levels and ameliorates leukocyte-endothelium interactions, oxidative stress and inflammation in T2D patients. Anthropometric and metabolic parameters were studied in 51 T2D patients and 57 controls. Production of mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential, glutathione content, leukocyte-endothelium interactions, NFκB-p65, TNFα and SIRT1 levels was measured in leukocytes treated or not with SS-31. We observed increased mitochondrial ROS production that was restored by SS-31 treatment. SS-31 also increased mitochondrial membrane potential, glutathione content, SIRT1 levels and leukocyte rolling velocity and reduced rolling flux and adhesion in T2D patients. NFκB-p65 and TNFα, which were enhanced in diabetic patients, were also reduced by SS-31 treatment. Our results reveal that SS-31 exerts beneficial effects on the leukocytes of T2D patients by reducing oxidative stress, leukocyte-endothelium interactions, NFκB and TNFα and by increasing SIRT1 levels. These actions support its use as a potential agent against CVD risk.

Changes in cerebral [18F]-FDG uptake induced by acute alcohol administration in a rat model of alcoholism.

Several [18F]-FDG positron emission tomography (PET) studies in alcoholics have consistently reported decreases in overall brain glucose metabolism at rest and following acute alcohol administration. However, changes in cerebral glucose utilization associated with the transition to addiction are not well understood and require longitudinal translational imaging studies in animal models of alcoholism. Here, we studied brain glucose uptake in alcohol drinking rats in order to provide convergent evidence to what has previously been reported in human studies. Brain glucose metabolism was measured by [18F]-FDG microPET imaging in different male Wistar rat groups: short-term drinking (three months), long-term drinking (twelve months) and alcohol-naïve. Global and regional cerebral glucose uptake was measured at rest and following acute alcohol administration. We showed that alcohol significantly reduced the whole-brain glucose metabolism. This effect was most pronounced in the parietal cortex and cerebellum. Alcohol-induced decreases in brain [18F]-FDG uptake was most apparent in alcohol-naïve rats, less intense in short-term drinkers and absent in long-term drinkers. The latter finding indicates the occurrence of tolerance to the intoxicating effects of alcohol in long-term drinking individuals. In contrast, some regions, like the ventral striatum and entorhinal cortex, showed enhanced metabolic activity, an effect that did not undergo tolerance during long-term alcohol consumption. Our findings are comparable to those described in human studies using the same methodology. We conclude that [18F]-FDG PET studies in rat models of alcoholism provide good translation and can be used for future longitudinal studies investigating alterations in brain function during different stages of the addiction cycle.

The pivotal role of nitric oxide: effects on the nervous and immune systems.

Nitric oxide (NO) has an important role in physiological and pathological processes in general, and in particular plays a homeostatic role in the nervous and immune systems. The many different physiological functions of NO include those of a mediator of blood vessel dilation, neurotransmitter, neuromodulator and inductor of mitochondrial biogenesis. In addition, NO can transform into highly reactive and harmful molecules producing an impairment of the DNA, lipids or proteins, and thus altering their function. This dual action of NO, by which it plays an important role in homeostasis and aids the development of pathological processes, makes this molecule an interesting target for medical therapies, especially with respect to the nervous and immune systems. This review describes the multiple roles of NO played out in the nervous and immune systems during different physiological and pathophysiological processes.

Mitochondrial dysfunction and oxidative stress in insulin resistance.

Evidence is mounting of the involvement of mitochondrial dysfunction in insulin resistance, diabetes and associated complications. This review aims to provide an overview of the effects of insulin resistance on mitochondrial function in several tissues. We consider the pathogenesis of insulin resistance from a mitochondrial perspective and contemplate potential beneficial effects of strategies aimed at modulating mitochondrial function in insulin resistance, including insulin and insulin-sensitizing drugs, antioxidants, and selectively targeting antioxidants to mitochondria.

Rapid and high-yielding cysteine labelling of peptides with N-succinimidyl 4-[18F]fluorobenzoate.

Fast cysteine labelling of peptides promoted by an adjacent arginine has been observed with a standard labelling agent specific for amines, N-succinimidyl 4-[(18)F]fluorobenzoate.

A ¹8F-fluorodeoxyglucose MicroPET imaging study to assess changes in brain glucose metabolism in a rat model of surgery-induced latent pain sensitization.

BACKGROUND: Neuroplastic changes involved in latent pain sensitization after surgery are poorly defined. We assessed temporal changes in glucose brain metabolism in a postoperative rat model using positron emission tomography. We also investigated brain metabolism after naloxone administration. METHODS: Rats were given remifentanil anesthetic and underwent a plantar incision, with 1 mg/kg of (-)-naloxone subcutaneously administered on postoperative days 20 and 21. Using the von Frey test, mechanical thresholds were measured pre- and postoperatively at different time points in awake animals during F-fluorodeoxyglucose (F-FDG) uptake. Brain images were also obtained the day before mechanical testing, using a positron emission tomography R4 scanner (Concorde Microsystems, Siemens, Knoxville, TN). Differences in brain activity were assessed utilizing a statistical parametric mapping. RESULTS: Surgery induced minor changes in F-FDG uptake in the cerebellum, hippocampus, and posterior cortex, which extended to the thalamus, hypothalamus, and brainstem on days 6 and 7. Changes were still present on day 21. Maximal postoperative hypersensitivity was observed on day 2. The administration of (-)-naloxone on day 21 induced significant hypersensitivity, greatly enhancing the effect on F-FDG uptake. In sham-operated rats, naloxone induced changes limited to the striatum and the cerebellum. Nonnociceptive stimulation with von Frey filaments had no effect on F-FDG uptake. CONCLUSIONS: Surgery, remifentanil, and their combination induced long-lasting and significant metabolic changes in the pain brain matrix, with a positive correlation with hypersensitivity after naloxone. Changes in brain F-FDG precipitated by naloxone suggest that surgery under remifentanil anesthetic induces the greatest neuroplastic brain adaptations in opioid-related pathways involved in nociceptive processing and long-lasting pain sensitization.

Complex I dysfunction and tolerance to nitroglycerin: an approach based on mitochondrial-targeted antioxidants.

Nitroglycerin (GTN) tolerance was induced in vivo (rats) and in vitro (rat and human vessels). Electrochemical detection revealed that the incubation dose of GTN (5x10(-6) mol/L) did not release NO or modify O(2) consumption when administered acutely. However, development of tolerance produced a decrease in both mitochondrial O(2) consumption and the K(m) for O(2) in animal and human vessels and endothelial cells in a noncompetitive action. GTN tolerance has been associated with impairment of GTN biotransformation through inhibition of aldehyde dehydrogenase (ALDH)-2, and with uncoupling of mitochondrial respiration. Feeding rats with mitochondrial-targeted antioxidants (mitoquinone [MQ]) and in vitro coincubation with MQ (10(-6) mol/L) or glutathione (GSH) ester (10(-4) mol/L) prevented tolerance and the effects of GTN on mitochondrial respiration and ALDH-2 activity. Biotransformation of GTN requires functionally active mitochondria and induces reactive oxygen species production and oxidative stress within this organelle, as it is inhibited by mitochondrial-targeted antioxidants and is absent in HUVECrho(0) cells. Experiments analyzing complex I-dependent respiration demonstrate that its inhibition by GTN is prevented by mitochondrial-targeted antioxidants. Furthermore, in presence of succinate (10x10(-3) mol/L), a complex II electron donor added to bypass complex I-dependent respiration, GTN-treated cells exhibited O(2) consumption rates similar to those of controls, thus suggesting that complex I was affected by GTN. We propose that, following prolonged treatment with GTN in addition to ALDH-2, complex I is a target for mitochondrially generated reactive oxygen species. Our data also suggest a role for mitochondrial-targeted antioxidants as therapeutic tools in the control of the tolerance that accompanies chronic nitrate use.

Ionic liquids as a novel medium for photochemical reactions. Ru(bpy)(3)2+/ viologen in imidazolium ionic liquid as a photocatalytic system mimicking the oxido-reductase enzyme.

Ionic liquids are suitable media which stabilize charged intermediates favoring those mechanisms that occur through charge separation. We have used ionic liquids to develop a photocatalytic system to perform the reduction of a carbonyl group to alcohol, thus mimicking the behavior of the reductase enzymes. The photochemical cycle is based on the well-known electron transfer from the Ru(bpy)(3)2+ complex in its excited state, acting as electron donor to MV2+, which acts as electron acceptor. The initial electron transfer process can be promoted upon selective Ru(bpy)(3)2+ excitation by visible light. By means of laser flash photolysis we have provided evidence of the nature and lifetimes of the intermediates involved in the photocatalytic system. Thus, the initial electron transfer between Ru(bpy)(3)2+ triplets and viologen MV2+ forms the MV*+ radical cation, which upon accepting an H* atom from a suitable hydrogen atom donor, forms the corresponding dihydropyridine MVH+ reducing agent.

Spectroscopy and photophysics of flavin-related compounds: 3-benzyl-lumiflavin.

Molecular structure, spectroscopic and photophysical data for the singlet state of 3-benzyl-lumiflavin in different solvents are presented. Theoretical studies concerning singlet-singlet and triplet-triplet excitation energies were carried out using time-dependent density functional theory (TD-DFT) calculations. These predictions are in good agreement with the experimental results, which reflect the solvent interactions. All the observable singlet-singlet transitions have pi-pi* character. The title compound appears to be an efficient sensitizer of the production of singlet oxygen (phi(Delta)= 0.53). The crystal structure of 3-benzyl-lumiflavin is also presented, along with its solid-state photophysical data.