Oxidative stress enhances the expression of sulfur assimilation genes: preliminary insights on the Enterococcus faecalis iron-sulfur cluster machinery regulation

The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.

Effect of a specific supplement enriched with n-3 polyunsaturated fatty acids on markers of inflammation, oxidative stress and metabolic status of ear, nose and throat cancer patients.

Malnutrition affects 40-50% of patients with ear, nose and throat (ENT) cancer. The aim of this study was to assess changes induced by a specific nutritional supplement enriched with n-3 polyunsaturated fatty acids, fiber and greater amounts of proteins and electrolytes, as compared with a standard nutritional supplement, on markers of inflammation, oxidative stress and metabolic status of ENT cancer patients undergoing radiotherapy (RT). Fourteen days after starting RT, 26 patients were randomly allocated to one of two groups, 13 supplemented with Prosure, an oncologic formula enriched with n-3 polyunsaturated fatty acids, fiber and greater amounts of proteins and electrolytes (specific supplement), and 13 supplemented with Standard-Isosource (standard supplement). Patients were evaluated before RT, and 14, 28 and 90 days after starting RT. The results showed that there were no significant differences between the groups, but greater changes were observed in the standard supplement group, such as a decline in body mass index (BMI), reductions in hematocrit, erythrocyte, eosinophil and albumin levels, and a rise in creatinine and urea levels. We concluded that metabolic, inflammatory and oxidative stress parameters were altered during RT, and began to normalize at the end of the study. Patients supplemented with Prosure showed an earlier normalization of these parameters, with more favorable changes in oxidative stress markers and a more balanced evolution, although the difference was not significant.

Comparison of oxidative stress markers in HIV-infected patients on efavirenz or atazanavir/ritonavir-based therapy.

INTRODUCTION Chronic low-grade inflammation and immune activation may persist in HIV patients despite effective antiretroviral therapy (ART). These abnormalities are associated with increased oxidative stress (OS). Bilirubin (BR) may have a beneficial role in counteracting OS. Atazanavir (ATV) inhibits UGT1A1, thus increasing unconjugated BR levels, a distinctive feature of this drug. We compared changes in OS markers in HIV patients on ATV/r versus efavirenz (EFV)-based first-line therapies. MATERIALS AND METHODS Cohort of the Spanish Research Network (CoRIS) is a multicentre, open, prospective cohort of HIV-infected patients naïve to ART at entry and linked to a biobank. We identified hepatitis C virus/hepatitis B virus (HCV/HBV) negative patients who started first-line ART with either ATV/r or EFV, had a baseline biobank sample and a follow-up sample after at least nine months of ART while maintaining initial regimen and being virologically suppressed. Lipoprotein-associated Phospholipase A2 (Lp-PLA2), Myeloperoxidase (MPO) and Oxidized LDL (OxLDL) were measured in paired samples. Marker values at one year were interpolated from available data. Multiple imputations using chained equations were used to deal with missing values. Change in the OS markers was modelled using multiple linear regressions adjusting for baseline marker values and baseline confounders. Correlations between continuous variables were explored using Pearson's correlation tests. RESULTS 145 patients (97 EFV; 48 ATV/r) were studied. Mean (SD) baseline values for OS markers in EFV and ATV/r groups were: Lp-PLA2 [142.2 (72.8) and 150.1 (92.8) ng/mL], MPO [74.3 (48.2) and 93.9 (64.3) µg/L] and OxLDL [76.3 (52.3) and 82.2 (54.4) µg/L]. After adjustment for baseline variables patients on ATV/r had a significant decrease in Lp-PLA2 (estimated difference -16.3 [CI 95%: -31.4, -1.25; p=0.03]) and a significantly lower increase in OxLDL (estimated difference -21.8 [-38.0, -5.6; p<0.01] relative to those on EFV, whereas no differences in MPO were found. Adjusted changes in BR were significantly higher for the ATV/r group (estimated difference 1.33 [1.03, 1.52; p<0.01]). Changes in BR and changes in OS markers were significantly correlated. CONCLUSIONS In virologically suppressed patients on stable ART, OS was lower in ATV/r-based regimens compared to EFV. We hypothesize these changes could be in part attributable to increased BR plasma levels.

Regulation of cell death receptor S-nitrosylation and apoptotic signaling by Sorafenib in hepatoblastoma cells.

Nitric oxide (NO) plays a relevant role during cell death regulation in tumor cells. The overexpression of nitric oxide synthase type III (NOS-3) induces oxidative and nitrosative stress, p53 and cell death receptor expression and apoptosis in hepatoblastoma cells. S-nitrosylation of cell death receptor modulates apoptosis. Sorafenib is the unique recommended molecular-targeted drug for the treatment of patients with advanced hepatocellular carcinoma. The present study was addressed to elucidate the potential role of NO during Sorafenib-induced cell death in HepG2 cells. We determined the intra- and extracellular NO concentration, cell death receptor expression and their S-nitrosylation modifications, and apoptotic signaling in Sorafenib-treated HepG2 cells. The effect of NO donors on above parameters has also been determined. Sorafenib induced apoptosis in HepG2 cells. However, low concentration of the drug (10nM) increased cell death receptor expression, as well as caspase-8 and -9 activation, but without activation of downstream apoptotic markers. In contrast, Sorafenib (10µM) reduced upstream apoptotic parameters but increased caspase-3 activation and DNA fragmentation in HepG2 cells. The shift of cell death signaling pathway was associated with a reduction of S-nitrosylation of cell death receptors in Sorafenib-treated cells. The administration of NO donors increased S-nitrosylation of cell death receptors and overall induction of cell death markers in control and Sorafenib-treated cells. In conclusion, Sorafenib induced alteration of cell death receptor S-nitrosylation status which may have a relevant repercussion on cell death signaling in hepatoblastoma cells.

Rethinking the triggering inflammatory processes of chronic periaortitis.

Chronic periaortitis (CP) is an uncommon inflammatory disease which primarily involves the infrarenal portion of the abdominal aorta. However, CP should be regarded as a generalized disease with three different pathophysiological entities, namely idiopathic retroperitoneal fibrosis (RPF), inflammatory abdominal aortic aneurysm and perianeurysmal RPF. These entities share similar histopathological characteristics and finally will lead to fibrosis of the retroperitoneal space. Beside fibrosis, an infiltrate with variable chronic inflammatory cell is present. The majority of these cells are lymphocytes and macrophages as well as vascular endothelial cells, most of which are HLA-DR-positive. B and T cells are present with a majority of T cells of the T-helper phenotype. Cytokine gene expression analysis shows the presence of interleukin (IL)-1alpha, IL-2, IL-4, interferon-gamma and IL-2 receptors. Adhesion molecules such as E-selectin, intercellular adhesion molecule-1 and the vascular cell adhesion molecule-1 were also found in aortic tissue, and may play a significant role in CP pathophysiology. Although CP pathogenesis remains unknown, an exaggerated inflammatory response to advanced atherosclerosis (ATS) has been postulated to be the main process. Autoimmunity has also been proposed as a contributing factor based on immunohistochemical studies. The suspected allergen may be a component of ceroid, which is elaborated within the atheroma. We review the pathogenesis and the pathophysiology of CP, and its potential links with ATS. Clinically relevant issues are summarized in each section with regard to the current working hypothesis of this complex inflammatory disease.

@neurIST infrastructure for advanced disease management through integration of heterogeneous data, computing, and complex processing services

The increasing volume of data describing humandisease processes and the growing complexity of understanding, managing, and sharing such data presents a huge challenge for clinicians and medical researchers. This paper presents the@neurIST system, which provides an infrastructure for biomedical research while aiding clinical care, by bringing together heterogeneous data and complex processing and computing services. Although @neurIST targets the investigation and treatment of cerebral aneurysms, the system’s architecture is generic enough that it could be adapted to the treatment of other diseases.Innovations in @neurIST include confining the patient data pertaining to aneurysms inside a single environment that offers cliniciansthe tools to analyze and interpret patient data and make use of knowledge-based guidance in planning their treatment. Medicalresearchers gain access to a critical mass of aneurysm related data due to the system’s ability to federate distributed informationsources. A semantically mediated grid infrastructure ensures that both clinicians and researchers are able to seamlessly access andwork on data that is distributed across multiple sites in a secure way in addition to providing computing resources on demand forperforming computationally intensive simulations for treatment planning and research.

Physical activity modulates heat shock protein-72 expression and limits oxidative damage accumulation in a healthy elderly population aged 60 90 years

BACKGROUND: Reactive oxygen species production increases during aging, whereas protective mechanisms such as heat shock proteins (HSPs) or antioxidant capacity are depressed. Physical activity has been hypothesized to provide protection against oxidative damage during aging, but results remain controversial. This study aimed to investigate the effect of different levels of physical activity during aging on Hsp72 expression and systemic oxidative stress at rest and in response to maximal exercise. METHODS: Plasma antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC), thiobarbituric acid-reactive species (TBARS), advanced oxidized proteins products (AOPP), and Hsp72 expression in leukocytes were measured before and after maximal exercise testing in 32 elderly persons (aged 73.2 years), who were assigned to two different groups depending on their level of physical activity during the past 12 months (OLow = moderate to low level; OHigh = higher level). RESULTS: The OHigh group showed higher aerobic fitness and TEAC (both representing 120% of OLow values) as well as lower oxidative damage (50% of OLow values) and Hsp72 expression. Exercise led to a lower increase in oxidative damage in the OHigh group. Aerobic fitness was positively correlated with TEAC and negatively with lipid peroxidation (TBARS). Hsp72 expression was negatively correlated with TEAC but positively correlated with TBARS levels. CONCLUSIONS: The key finding of this study is that, in people aged 60 to 90 years, long-term high level of physical activity preserved antioxidant capacity and limited oxidative damage accumulation. It also downregulated Hsp72 expression, an adaptation potentially resulting from lower levels of oxidative damage.

Constraint and cost of oxidative stress on reproduction: correlative evidence in laboratory mice and review of the literature.

ABSTRACT: BACKGROUND: One central concept in evolutionary ecology is that current and residual reproductive values are negatively linked by the so-called cost of reproduction. Previous studies examining the nature of this cost suggested a possible involvement of oxidative stress resulting from the imbalance between pro- and anti-oxidant processes. Still, data remain conflictory probably because, although oxidative damage increases during reproduction, high systemic levels of oxidative stress might also constrain parental investment in reproduction. Here, we investigated variation in oxidative balance (i.e. oxidative damage and antioxidant defences) over the course of reproduction by comparing female laboratory mice rearing or not pups. RESULTS: A significant increase in oxidative damage over time was only observed in females caring for offspring, whereas antioxidant defences increased over time regardless of reproductive status. Interestingly, oxidative damage measured prior to reproduction was negatively associated with litter size at birth (constraint), whereas damage measured after reproduction was positively related to litter size at weaning (cost). CONCLUSIONS: Globally, our correlative results and the review of literature describing the links between reproduction and oxidative stress underline the importance of timing/dynamics when studying and interpreting oxidative balance in relation to reproduction. Our study highlights the duality (constraint and cost) of oxidative stress in life-history trade-offs, thus supporting the theory that oxidative stress plays a key role in life-history evolution.

Mitochondrial dysfunction increases oxidative stress and decreases chronological life span in fission yeast

Background: Oxidative stress is a probable cause of aging and associated diseases. Reactive oxygen species (ROS) originate mainly from endogenous sources, namely the mitochondria. Methodology/Principal Findings: We analyzed the effect of aerobic metabolism on oxidative damage in Schizosaccharomyces pombe by global mapping of those genes that are required for growth on both respiratory-proficient media and hydrogen-peroxide-containing fermentable media. Out of a collection of approximately 2700 haploid yeast deletion mutants, 51 were sensitive to both conditions and 19 of these were related to mitochondrial function. Twelve deletion mutants lacked components of the electron transport chain. The growth defects of these mutants can be alleviated by the addition of antioxidants, which points to intrinsic oxidative stress as the origin of the phenotypes observed. These respiration-deficient mutants display elevated steady-state levels of ROS, probably due to enhanced electron leakage from their defective transport chains, which compromises the viability of chronologically-aged cells. Conclusion/Significance: Individual mitochondrial dysfunctions have often been described as the cause of diseases or aging, and our global characterization emphasizes the primacy of oxidative stress in the etiology of such processes.

Cannabinoid 1 receptor promotes cardiac dysfunction, oxidative stress, inflammation, and fibrosis in diabetic cardiomyopathy.

Endocannabinoids and cannabinoid 1 (CB(1)) receptors have been implicated in cardiac dysfunction, inflammation, and cell death associated with various forms of shock, heart failure, and atherosclerosis, in addition to their recognized role in the development of various cardiovascular risk factors in obesity/metabolic syndrome and diabetes. In this study, we explored the role of CB(1) receptors in myocardial dysfunction, inflammation, oxidative/nitrative stress, cell death, and interrelated signaling pathways, using a mouse model of type 1 diabetic cardiomyopathy. Diabetic cardiomyopathy was characterized by increased myocardial endocannabinoid anandamide levels, oxidative/nitrative stress, activation of p38/Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs), enhanced inflammation (tumor necrosis factor-α, interleukin-1β, cyclooxygenase 2, intracellular adhesion molecule 1, and vascular cell adhesion molecule 1), increased expression of CB(1), advanced glycation end product (AGE) and angiotensin II type 1 receptors (receptor for advanced glycation end product [RAGE], angiotensin II receptor type 1 [AT(1)R]), p47(phox) NADPH oxidase subunit, β-myosin heavy chain isozyme switch, accumulation of AGE, fibrosis, and decreased expression of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA2a). Pharmacological inhibition or genetic deletion of CB(1) receptors attenuated the diabetes-induced cardiac dysfunction and the above-mentioned pathological alterations. Activation of CB(1) receptors by endocannabinoids may play an important role in the pathogenesis of diabetic cardiomyopathy by facilitating MAPK activation, AT(1)R expression/signaling, AGE accumulation, oxidative/nitrative stress, inflammation, and fibrosis. Conversely, CB(1) receptor inhibition may be beneficial in the treatment of diabetic cardiovascular complications.

Effect of an 8-weeks aerobic training program in elderly on oxidative stress and HSP72 expression in leukocytes during antioxidant supplementation.

OBJECTIVE: To investigate the effect of aerobic training in the context of antioxidant supplementation on systemic oxidative stress and leukocytes heat shock protein (Hsp)72 expression in the elderly. DESIGN: Sixteen septuagenarians (8 males and 8 females, mean age 74.6) were supplemented with Vitamin C and E (respectively 500 and 100mg per day) and randomly assigned either to sedentary (AS) or individualized aerobically trained (AT) group for 8 weeks. METHODS: Plasma Vitamin C and E concentrations and aerobic fitness, as well as resting and post graded exercise (GXT) Hsp72 expression in leukocytes, plasma levels of thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein product (AOPP) were measured pre and post training / supplementation. RESULTS: At the end of the intervention, the two groups showed a significant increase in resting plasma vitamin C and E (approximately 50 and 20% increase respectively) and a significant decrease in both resting and post GXT plasma TBARS and AOPP (approximately 25 and 20% decrease respectively). These changes were of similar magnitude in the two groups. The reduced oxidative stress was concomitant with a 15% decreased expression of Hsp72 in monocytes and granulocytes in both groups. CONCLUSION: This study provides evidence that in elderly, increased concentration of antioxidant vitamins C and E is associated with a reduction in oxidative stress and leukocytes Hsp72. In this context, 8 weeks of aerobic training has no impact on oxidative stress or leukocytes Hsp72 expression in elderly people.

Ruin and related quantities in some advanced insurance risk models

Risk theory has been a very active research area over the last decades. The main objectives of the theory are to find adequate stochastic processes which can model the surplus of a (non-life) insurance company and to analyze the risk related quantities such as ruin time, ruin probability, expected discounted penalty function and expected discounted dividend/tax payments. The study of these ruin related quantities provides crucial information for actuaries and decision makers. This thesis consists of the study of four different insurance risk models which are essentially related. The ruin and related quantities are investigated by using different techniques, resulting in explicit or asymptotic expressions for the ruin time, the ruin probability, the expected discounted penalty function and the expected discounted tax payments. - La recherche en théorie du risque a été très dynamique au cours des dernières décennies. D'un point de vue théorique, les principaux objectifs sont de trouver des processus stochastiques adéquats permettant de modéliser le surplus d'une compagnie d'assurance non vie et d'analyser les mesures de risque, notamment le temps de ruine, la probabilité de ruine, l'espérance de la valeur actuelle de la fonction de pénalité et l'espérance de la valeur actuelle des dividendes et taxes. L'étude de ces mesures associées à la ruine fournit des informations cruciales pour les actuaires et les décideurs. Cette thèse consiste en l'étude des quatre différents modèles de risque d'assurance qui sont essentiellement liés. La ruine et les mesures qui y sont associées sont examinées à l'aide de différentes techniques, ce qui permet d'induire des expressions explicites ou asymptotiques du temps de ruine, de la probabilité de ruine, de l'espérance de la valeur actuelle de la fonction de pénalité et l'espérance de la valeur actuelle des dividendes et taxes.

Interplay of oxidative, nitrosative/nitrative stress, inflammation, cell death and autophagy in diabetic cardiomyopathy.

Diabetes is a recognized risk factor for cardiovascular diseases and heart failure. Diabetic cardiovascular dysfunction also underscores the development of diabetic retinopathy, nephropathy and neuropathy. Despite the broad availability of antidiabetic therapy, glycemic control still remains a major challenge in the management of diabetic patients. Hyperglycemia triggers formation of advanced glycosylation end products (AGEs), activates protein kinase C, enhances polyol pathway, glucose autoxidation, which coupled with elevated levels of free fatty acids, and leptin have been implicated in increased generation of superoxide anion by mitochondria, NADPH oxidases and xanthine oxidoreductase in diabetic vasculature and myocardium. Superoxide anion interacts with nitric oxide forming the potent toxin peroxynitrite via diffusion limited reaction, which in concert with other oxidants triggers activation of stress kinases, endoplasmic reticulum stress, mitochondrial and poly(ADP-ribose) polymerase 1-dependent cell death, dysregulates autophagy/mitophagy, inactivates key proteins involved in myocardial calcium handling/contractility and antioxidant defense, activates matrix metalloproteinases and redox-dependent pro-inflammatory transcription factors (e.g. nuclear factor kappaB) promoting inflammation, AGEs formation, eventually culminating in myocardial dysfunction, remodeling and heart failure. Understanding the complex interplay of oxidative/nitrosative stress with pro-inflammatory, metabolic and cell death pathways is critical to devise novel targeted therapies for diabetic cardiomyopathy, which will be overviewed in this brief synopsis. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.

Eumelanin- and pheomelanin-based colour advertise resistance to oxidative stress in opposite ways.

The control mechanisms and information content of melanin-based colourations are still debated among evolutionary biologists. Recent hypotheses contend that molecules involved in melanogenesis alter other physiological processes, thereby generating covariation between melanin-based colouration and other phenotypic attributes. Interestingly, several molecules such as agouti and glutathione that trigger the production of reddish-brown pheomelanin have an inhibitory effect on the production of black/grey eumelanin, whereas other hormones, such as melanocortins, have the opposite effect. We therefore propose the hypothesis that phenotypic traits positively correlated with the degree of eumelanin-based colouration may be negatively correlated with the degree of pheomelanin-based colouration, or vice versa. Given the role played by the melanocortin system and glutathione on melanogenesis and resistance to oxidative stress, we examined the prediction that resistance to oxidative stress is positively correlated with the degree of black colouration but negatively with the degree of reddish colouration. Using the barn owl (Tyto alba) as a model organism, we swapped eggs between randomly chosen nests to allocate genotypes randomly among environments and then we measured resistance to oxidative stress using the KRL assay in nestlings raised by foster parents. As predicted, the degree of black and reddish pigmentations was positively and negatively correlated, respectively, with resistance to oxidative stress. Our results reveal that eumelanin- and pheomelanin-based colourations can be redundant signals of resistance to oxidative stress.

Toxicity screenings of nanomaterials: challenges due to interference with assay processes and components of classic in vitro tests.

Given the multiplicity of nanoparticles (NPs), there is a requirement to develop screening strategies to evaluate their toxicity. Within the EU-funded FP7 NanoTEST project, a panel of medically relevant NPs has been used to develop alternative testing strategies of NPs used in medical diagnostics. As conventional toxicity tests cannot necessarily be directly applied to NPs in the same manner as for soluble chemicals and drugs, we determined the extent of interference of NPs with each assay process and components. In this study, we fully characterized the panel of NP suspensions used in this project (poly(lactic-co-glycolic acid)-polyethylene oxide [PLGA-PEO], TiO2, SiO2, and uncoated and oleic-acid coated Fe3O4) and showed that many NP characteristics (composition, size, coatings, and agglomeration) interfere with a range of in vitro cytotoxicity assays (WST-1, MTT, lactate dehydrogenase, neutral red, propidium iodide, (3)H-thymidine incorporation, and cell counting), pro-inflammatory response evaluation (ELISA for GM-CSF, IL-6, and IL-8), and oxidative stress detection (monoBromoBimane, dichlorofluorescein, and NO assays). Interferences were assay specific as well as NP specific. We propose how to integrate and avoid interference with testing systems as a first step of a screening strategy for biomedical NPs.