Hsp90β inhibition modulates nitric oxide production and nitric oxide-induced apoptosis in human chondrocytes

<p>Abstract</p> <p>Background</p> <p>Hsp90β is a member of the Hsp90 family of protein chaperones. This family plays essential roles in the folding, maturation and activity of many proteins that are involved in signal transduction and transcriptional regulation. The role of this protein in chondrocytes is not well understood, although its increase in osteoarthritic cells has been reported. The present study aimed to explore the role of Hsp90β in key aspects of OA pathogenesis.</p> <p>Methods</p> <p>Human OA chondrocytes were isolated from cartilage obtained from patients undergoing joint replacement surgery, and primary cultured. Cells were stimulated with proinflammatory cytokines (IL-1β or TNF-α) and nitric oxide donors (NOC-12 or SNP). For Hsp90β inhibition, two different chemical inhibitors (Geldanamycin and Novobiocin) were employed, or siRNA transfection procedures were carried out. Gene expression was determined by real-time PCR, apoptosis was quantified by flow cytometry and ELISA, and nitric oxide (NO) production was evaluated by the Griess method. Indirect immunofluorescence assays were performed to evaluate the presence of Hsp90β in stimulated cells.</p> <p>Results</p> <p>Hsp90β was found to be increased by proinflammatory cytokines. Inhibition of Hsp90β by the chemicals Geldanamycin (GA) and Novobiocin (NB) caused a dose-dependent decrease of the NO production induced by IL-1β in chondrocytes, up to basal levels. Immunofluorescence analyses demonstrate that the NO donors NOC-12 and SNP also increased Hsp90β. Chemical inhibition or specific gene silencing of this chaperone reduced the DNA condensation and fragmentation, typical of death by apoptosis, that is induced by NO donors in chondrocytes.</p> <p>Conclusions</p> <p>The present results show how Hsp90β modulates NO production and NO-mediated cellular death in human OA chondrocytes.</p

Mitochondrial Superoxide Contributes to Blood Flow and Axonal Transport Deficits in the Tg2576 Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by the progressive decline in cognitive functions and the deposition of aggregated amyloid beta (Abeta) into senile plaques and the protein tau into tangles. In addition, a general state of oxidation has long been known to be a major hallmark of the disease. What is not known however, are the mechanisms by which oxidative stress contributes to the pathology of AD.In the current study, we used a mouse model of AD and genetically boosted its ability to quench free radicals of specific mitochondrial origin. We found that such manipulation conferred to the AD mice protection against vascular as well as neuronal deficits that typically affect them. We also found that the vascular deficits are improved via antioxidant modulation of the endothelial nitric oxide synthase, an enzyme primarily responsible for the production of nitric oxide, while neuronal deficits are improved via modulation of the phosphorylation status of the protein tau, which is a neuronal cytoskeletal stabilizer.These findings directly link free radicals of specific mitochondrial origin to AD-associated vascular and neuronal pathology

Malaria parasite clearance from patients following artemisinin-based combination therapy in C&ocirc;te d&rsquo;Ivoire

Offianan Andre Toure,1 Tiacoh N&rsquo;Guessan Landry,1 Serge Brice Assi,2,3 Antoinette Amany Kone,1&nbsp;Eric Adji Gbessi,1&nbsp;Berenger Aristide Ako,1 Baba Coulibaly,1 Bouakary Kone,4 Oumar Ouattara,4 Sylvain Beourou,1 Alphonsine Koffi,2 Franck Remoue,2,5 Christophe Rogier6 1Malariology Unit, Pasteur Institute of C&ocirc;te d&rsquo;Ivoire, Abidjan, C&ocirc;te d&rsquo;Ivoire; 2Malaria and Anopheles Research and Management Unit, Pierre Richet Institute, Bouake, C&ocirc;te d&rsquo;Ivoire; 3National Malaria Control Program, Bouake, C&ocirc;te d&rsquo;Ivoire; 4Department of Medicine, Health Care Center of Dar-Es-Salam, Bouake, C&ocirc;te d&rsquo;Ivoire; 5UMR 224-MIVEGEC, Research Development Institute, Montpellier, France; 6Army Health Department, Paris, France Introduction: Parasite clearance is useful to detect artemisinin resistance. The aim of this study was to investigate parasite clearance in patients treated with artesunate + amodiaquine (AS + AQ) and artemether + lumefantrine (AL): the two artemisinin-based combination therapies (ACTs) recommended in the first-line treatment of uncomplicated malaria in C&ocirc;te d&rsquo;Ivoire.Methods: This study was conducted in Bouak&eacute;, C&ocirc;te d&rsquo;Ivoire, from April to June 2016. Patients aged at least 6 months with uncomplicated malaria and treated with AS + AQ or AL were hospitalized for 3 days, and follow-up assessments were performed on days 3, 7, 14, 21, 28, 35, and 42. Blood smears were collected at the time of screening, pre-dose, and 6-hour intervals following the first dose of administration until two consecutive negative smears were recorded, thereafter at day 3 and follow-up visits. Parasite clearance was determined using the Worldwide Antimalarial Resistance Network&rsquo;s parasite clearance estimator. The primary end points were parasite clearance rate and time.Results: A total of 120 patients (57 in the AS + AQ group and 63 in the AL group) were randomized among 298 patients screened. The median parasite clearance time was 30 hours (IQR, 24&ndash;36 hours), for each ACT. The median parasite clearance rate had a slope half-life of 2.36 hours (IQR, 1.85&ndash;2.88 hours) and 2.23 hours (IQR, 1.74&ndash;2.63 hours) for AS + AQ and AL, respectively. The polymerase chain reaction-corrected adequate clinical and parasitological response was 100% and 98.07% at day 42 for AS + AQ and AL, respectively.Conclusion: Patients treated with AS + AQ and AL had cleared parasites rapidly. ACTs are still efficacious in Bouak&eacute;, C&ocirc;te d&rsquo;Ivoire, but continued efficacy monitoring of ACTs is needed. Keywords: Plasmodium falciparum, ACTs, parasite clearance, C&ocirc;te d&rsquo;Ivoir

Credit Where It's Due? Valence Politics, Attributions of Responsibility, and Multi-Level Elections

When considering elections in multi-level contexts, scholars have typically assumed-in line with second-order election theory-that the way voters approach an election depends on their attributions of responsibility, that is, on what they see as being at stake in that election. This assumption is questionable. The formal position is not always clear, and is further blurred by parties and the media. Moreover, many voters pay little attention to politics and have little incentive to trace constitutional responsibilities. In this paper I use data from election studies in two multi-level contexts, Ontario and Scotland, to explore the nature and impact of voters' attributions of responsibility. The evidence suggests that, when called upon in surveys to do so, many voters can confidently and fairly accurately assign issues to different levels of government. Yet they do not seem to consider these attributions much at elections. There is very little indication that issues weighed heavier in the decision-making of those who regarded them as the responsibility of that electoral arena. A plausible explanation is that most voters sidestep the cognitive demands imposed by multi-level elections

Targeting inflammasomes in rheumatic diseases.

Inflammasomes are key inducers of inflammation in response to exogenous and endogenous stimuli, because they regulate the processing and secretion of the proinflammatory cytokines IL-1β and IL-18. Thus, inflammasomes have a crucial role in host defence against infection, but they can also be involved in inflammatory diseases. Indeed, the NLRP3 (NOD-, LRR- and pyrin domain-containing 3) inflammasome has been shown to play a part in several inflammatory rheumatic disorders, although the mechanisms involved are better elucidated in some of these diseases than in others. In particular, the pathogenesis of cryopyrin-associated periodic syndromes and microcrystal-induced arthritides is thought to be dependent on activation of the NLRP3 inflammasome, and IL-1 inhibition has shown efficacy as a therapeutic strategy in both groups of conditions. In this Review, we describe the current understanding of the mechanisms that trigger the inflammasome, and consider the relevance of the inflammasome to a variety of rheumatic diseases. In addition, we discuss the current therapies targeting this molecular complex, as well as future therapeutic prospects

Pesticidal plants for stored product pests on small-holder farms in Africa

Despite the near elimination of pests from food stores in industrialised nations, insects are still the most important challenge to food security for small-holder farmers in less developed nations. Losses are frequently as high as 20 %. Synthetic products provide effective control when used correctly but are not sustainable or universally appropriate and present many challenges for farmers, not least of all their cost. Pesticidal plants offer an economic, effective and often the only alternative. Much published research, however, overlooks critical knowledge gaps providing outputs that are unlikely to improve pesticidal plant use or improve food security. This chapter identifies opportunities for better targeted research and improvements for uptake and use of pesticidal plants. We also highlight how a deeper understanding of different morphs, gender and age of insect can influence experimental results and should be considered more carefully. To be effective plant materials need to show low animal and environmental toxicity at typical application levels but at the same time be effective against a wide range of target species, at low doses and with longevity. They must also be low cost, safe, compatible with other pest management technologies and stable and have no consequences for the stored products such as impairing flavour. Research should be targeted at optimising the efficacy of the pesticidal plants already known to have potential, and this should be supported by chemistry to fully understand spatial, temporal and phenotypic variability and nontarget impacts. Availability of plants is a limiting factor to uptake so propagation and cultivation of elite provenances would alleviate pressure on natural ecosystems and improve reliability of efficacy and supply when supported by improved harvesting techniques. The large-scale commercialisation of plants may not compete with synthetic products globally but local production may foster a mechanism to support and encourage uptake through local markets and value chains