Détermination de l’effet protecteur des liposomes non phospholipidiques à haute teneur en cholestérol

Nous démontrons qu'il est possible de former des bicouches fluides non phospholipides en milieu aqueux avec un mélange d'acide palmitique (PA), cholestérol (Chol) et sulfate de cholestérol (Schol) avec une proportion molaire de 30/28/42. Ces liposomes non phospholipidiques peuvent maintenir un gradient de pH (pHinterne 8 / pHexterne 6) sur une période 100 fois plus longue que les liposomes faits de 1-palmitoyl-2-oléoyl-sn-glycéro-3-phosphocholine (POPC) et de cholestérol (60/40 mol/mol). De plus, ces LUV non phospholipidiques protègent l'acide ascorbique d'un milieu oxydant (1 mM de fer (III)). Une fois piégé dans les liposomes, l'acide ascorbique présente une vitesse de dégradation similaire à celle obtenue en l'absence de fer(III). Ces performances illustrent la perméabilité exceptionnellement limitée de ces liposomes, ce qui implique qu'ils peuvent présenter des avantages comme nanocontenants pour certaines applications. D'autre part, des vésicules unilamellaires géantes (GUV pour Giant Unilamellar Vesicles) ont été formées à partir d'un mélange d'acide palmitique et de cholestérol (30/70 mol/mol). Ces GUV sont stables sur l'échelle de temps de semaines, elles ne s'agrègent pas et elles sont sensibles au pH. Afin d'établir la formation des GUV, l'imagerie par microscopie confocale à balayage laser a été utilisée. Deux sondes fluorescentes ont été utilisées: le rouge du Nile, une sonde hydrophobe qui s'insère dans le cœur hydrophobe des bicouches lipidiques, et la calcéine, une sonde hydrophile qui a été emprisonné dans le réservoir interne des GUV. Cette approche a permis l'observation des parois des GUV ainsi que de leur contenu. Ces résultats montrent la possibilité de former de nouveaux microcontenants à partir d'un mélange d'un amphiphile monoalkylé et de stérol.First, we demonstrate that it is possible to form non-phospholipid fluid bilayers in aqueous milieu with a mixture of palmitic acid (PA), cholesterol (Chol), and cholesterol sulfate (Schol) in a molar proportion of 30/28/42. These non-phospholipid liposomes can sustain a pH gradient (pHinternal 8 / pHexternal 6) 100 times longer than LUVs made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol (60/40 mol/mol). These non-phospholipid LUVs are shown to protect ascorbic acid from an oxidizing environment (1 mM Iron (III)). Once entrapped in these liposomes, ascorbic acid displays a degradation rate similar to that obtained in the absence of Iron (III). This ability illustrates the exceptionally limited permeability of these liposomes, indicating that they can present advantages as nanocontainers for some applications. Second, Giant Unilamellar Vesicles (GUVs) were formed from a mixture of palmitic acid and cholesterol (30/70 mol/mol). These GUVs were stable over weeks, did not aggregate, and were pH-sensitive. In order to establish their formation, confocal laser scanning microscopy imaging was carried out. Two fluorescent probes were used: Nile Red, a hydrophobic probe that inserted in the hydrophobic core of lipid bilayers, and calcein, a hydrophilic probe that was trapped in the GUV internal pool. This approach allowed observation of both the walls of the GUVs as well as their entrapped content. These results show the possibility to form novel microcontainers from a mixture of a monoalkylated amphiphile and sterols

Data-Driven Analysis of Engagement in Gamified Learning Environments: A Methodology for Real-Time Measurement of MOOCs

Welfare and economic development is directly dependent on the availability of highly skilled and educated individuals in society. In the UK, higher education is accessed by a large percentage of high school graduates (50% in 2017). Still, in Brazil, a limited number of pupils leaving high schools continue their education (up to 20%). Initial pioneering efforts of universities and companies to support pupils from underprivileged backgrounds, to be able to succeed in being accepted by universities include personalised learning solutions. However, initial findings show that typical distance learning problems occur with the pupil population: isolation, demotivation, and lack of engagement. Thus, researchers and companies proposed gamification. However, gamification design is traditionally exclusively based on theory-driven approaches and usually ignore the data itself. This paper takes a different approach, presenting a large-scale study that analysed, statistically and via machine learning (deep and shallow), the first batch of students trained with a Brazilian gamified intelligent learning software (called CamaleOn), to establish, via a grassroots method based on learning analytics, how gamification elements impact on student engagement. The exercise results in a novel proposal for real-time measurement on Massive Open Online Courses (MOOCs), potentially leading to iterative improvements of student support. It also specifically analyses the engagement patterns of an underserved community

Synthetic RNA Silencing of Actinorhodin Biosynthesis in Streptomyces coelicolor A3(2)

We demonstrate the first application of synthetic RNA gene silencers in Streptomyces coelicolor A3(2). Peptide nucleic acid and expressed antisense RNA silencers successfully inhibited actinorhodin production. Synthetic RNA silencing was target-specific and is a new tool for gene regulation and metabolic engineering studies in Streptomyces.Peer reviewe

Os efeitos do cigarro e do consumo de café sobre a formação óssea e a integração óssea de implantes de hidroxiapatita

The present study aims to assess the effects of cigarette smoke inhalation and/or coffee consumption on bone formation and osseous integration of a dense hydroxyapatite (DHA) implant in rats. For this study, 20 male rats were divided into four groups (n = 5): CT (control) group, CE (coffee) group, CI (cigarette) group and CC (coffee + cigarette) group. During 16 weeks, animals in the CI group were exposed to cigarette smoke inhalation equivalent to 6 cigarettes per day; specimens in the CE group drank coffee as liquid diet; and rats in the CC group were submitted to both substances. In the 6th week a 5 mm slit in the parietal bone and a 4 mm slit in the tibia were performed on the left side: the former was left open while the latter received a DHA implant. As soon as surgeries were finished, the animals returned to their original protocols and after 10 weeks of exposure they were euthanised (ethically sacrificed) and the mentioned bones collected for histological processing. Data showed that exposure to cigarette smoke inhalation and coffee consumption did not interfere in weight gain and that solid and liquid diet consumption was satisfactory. Rats in the CC group showed a decrease in bone neoformation around the tibial DHA implant (31.8 ± 2.8) as well as in bone formation in the parietal slit (28.6 ± 2.2). On their own, cigarette smoke inhalation or coffee consumption also led to diminished bone neoformation around the implant and delayed the bone repair process in relation to the CT group. However, reduction in the bone repair process was accentuated with exposure to both cigarette smoke inhalation and coffee consumption in this study.O presente estudo teve como objetivo avaliar os efeitos do tabagismo e do consumo de café, isolada ou concomitantemente, sobre a formação óssea e a osseointegração de implantes hidroxiapatita densa. Foram utilizados 20 ratos machos, divididos em quatro grupos (n = 5): grupo CT (controle); grupo CA (café); grupo CI (cigarro), e grupo CC (cigarro + café). Durante 16 semanas, os animais do grupo CI foram expostos à fumaça de seis cigarros/dia; os animais do grupo CA consumiram café como dieta líquida, e os animais do grupo CC, ambas as substâncias. Após seis semanas de exposição, uma falha óssea de 5 mm foi produzida no osso parietal esquerdo e de 4 mm, na tíbia esquerda dos animais. A falha do parietal foi mantida aberta, enquanto na tíbia corpos cerâmicos de hidroxiapatita densa (HAD) foram implantados em cavidade produzida cirurgicamente. Após as cirurgias, os animais retornaram aos protocolos experimentais e, ao término de dez semanas, foram eutanasiados, sendo as tíbias e os parietais coletados para processamento histológico. A exposição à fumaça do cigarro e o consumo de café não interferiram no ganho de peso dos animais, e os consumos de dieta líquida e sólida foram satisfatórios entre os grupos. Os animais do grupo CC apresentaram menor volume de osso neoformado ao redor do implante de HAD na tíbia (31,8 ± 2,8) e menor osteogênese na falha produzida no osso parietal (28,6 ± 2,2). O café e o cigarro consumidos isoladamente provocam a diminuição do volume de osso ao redor do implante e o atraso no processo de reparação óssea. Observou-se que o consumo de café associado à exposição à fumaça do cigarro reduziu de forma acentuada o processo de reparação óssea, no presente estudo.Universidade José do Rosário VellanoUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUniversidade Federal de AlfenasUniversidade Estadual de CampinasUniversidade José do Rosário Vellano Faculdade de MedicinaUNIFESP, EPMSciEL

Novel insights into the cardio-protective effects of FGF21 in lean and obese rat hearts

Aims: Fibroblast growth factor 21 (FGF21) is a hepatic metabolic regulator with pleotropic actions. Its plasma concentrations are increased in obesity and diabetes; states associated with an increased incidence of cardiovascular disease. We therefore investigated the direct effect of FGF21 on cardio-protection in obese and lean hearts in response to ischemia. Methods and Results: FGF21, FGF21-receptor 1 (FGFR1) and beta-Klotho (βKlotho) were expressed in rodent, human hearts and primary rat cardiomyocytes. Cardiac FGF21 was expressed and secreted (real time RT-PCR/western blot and ELISA) in an autocrine-paracrine manner, in response to obesity and hypoxia, involving FGFR1-βKlotho components. Cardiac-FGF21 expression and secretion were increased in response to global ischemia. In contrast βKlotho was reduced in obese hearts. In isolated adult rat cardiomyocytes, FGF21 activated PI3K/Akt (phosphatidylinositol 3-kinase/Akt), ERK1/2(extracellular signal-regulated kinase) and AMPK (AMP-activated protein kinase) pathways. In Langendorff perfused rat [adult male wild-type wistar] hearts, FGF21 administration induced significant cardio-protection and restoration of function following global ischemia. Inhibition of PI3K/Akt, AMPK, ERK1/2 and ROR-α (retinoic-acid receptor alpha) pathway led to significant decrease of FGF21 induced cardio-protection and restoration of cardiac function in response to global ischemia. More importantly, this cardio-protective response induced by FGF21 was reduced in obesity, although the cardiac expression profiles and circulating FGF21 levels were increased. Conclusion: In an ex vivo Langendorff system, we show that FGF21 induced cardiac protection and restoration of cardiac function involving autocrine-paracrine pathways, with reduced effect in obesity. Collectively, our findings provide novel insights into FGF21-induced cardiac effects in obesity and ischemia

Macroscopic quantum resonators (MAQRO)

Quantum physics challenges our understanding of the nature of physical reality and of space-time and suggests the necessity of radical revisions of their underlying concepts. Experimental tests of quantum phenomena involving massive macroscopic objects would provide novel insights into these fundamental questions. Making use of the unique environment provided by space, MAQRO aims at investigating this largely unexplored realm of macroscopic quantum physics. MAQRO has originally been proposed as a medium-sized fundamental-science space mission for the 2010 call of Cosmic Vision. MAQRO unites two experiments: DECIDE (DECoherence In Double-Slit Experiments) and CASE (Comparative Acceleration Sensing Experiment). The main scientific objective of MAQRO, which is addressed by the experiment DECIDE, is to test the predictions of quantum theory for quantum superpositions of macroscopic objects containing more than 10e8 atoms. Under these conditions, deviations due to various suggested alternative models to quantum theory would become visible. These models have been suggested to harmonize the paradoxical quantum phenomena both with the classical macroscopic world and with our notion of Minkowski space-time. The second scientific objective of MAQRO, which is addressed by the experiment CASE, is to demonstrate the performance of a novel type of inertial sensor based on optically trapped microspheres. CASE is a technology demonstrator that shows how the modular design of DECIDE allows to easily incorporate it with other missions that have compatible requirements in terms of spacecraft and orbit. CASE can, at the same time, serve as a test bench for the weak equivalence principle, i.e., the universality of free fall with test-masses differing in their mass by 7 orders of magnitude.Comment: Proposal for a medium-sized space mission, 28 pages, 9 figures - in v2, we corrected some minor mistakes and replaced fig. 9 with a higher-resolution version; Experimental Astronomy, March 2012, Online, Open Acces

Interleukin 10 inhibits pro-inflammatory cytokine responses and killing of Burkholderia pseudomallei.

Melioidosis, caused by Burkholderia pseudomallei, is endemic in northeastern Thailand and Northern Australia. Severe septicemic melioidosis is associated with high levels of pro-inflammatory cytokines and is correlated with poor clinical outcomes. IL-10 is an immunoregulatory cytokine, which in other infections can control the expression of pro-inflammatory cytokines, but its role in melioidosis has not been addressed. Here, whole blood of healthy seropositive individuals (n = 75), living in N. E. Thailand was co-cultured with B. pseudomallei and production of IL-10 and IFN-γ detected and the cellular sources identified. CD3- CD14+ monocytes were the main source of IL-10. Neutralization of IL-10 increased IFN-γ, IL-6 and TNF-α production and improved bacteria killing. IFN-γ production and microbicidal activity were impaired in individuals with diabetes mellitus (DM). In contrast, IL-10 production was unimpaired in individuals with DM, resulting in an IL-10 dominant cytokine balance. Neutralization of IL-10 restored the IFN-γ response of individuals with DM to similar levels observed in healthy individuals and improved killing of B. pseudomallei in vitro. These results demonstrate that monocyte derived IL-10 acts to inhibit potentially protective cell mediated immune responses against B. pseudomallei, but may also moderate the pathological effects of excessive cytokine production during sepsis

The Association between Intrauterine Inflammation and Spontaneous Vaginal Delivery at Term: A Cross-Sectional Study

BACKGROUND:Different factors contribute to the onset of labor at term. In animal models onset of labor is characterized by an inflammatory response. The role of intrauterine inflammation, although implicated in preterm birth, is not yet established in human term labor. We hypothesized that intrauterine inflammation at term is associated with spontaneous onset of labor. METHODS/RESULTS:In two large urban hospitals in the Netherlands, a cross-sectional study of spontaneous onset term vaginal deliveries and elective caesarean sections (CS), without signs of labor, was carried out. Placentas and amniotic fluid samples were collected during labor and/or at delivery. Histological signs of placenta inflammation were determined. Amniotic fluid proinflammatory cytokine concentrations were measured using ELISA. A total of 375 women were included. In term vaginal deliveries, more signs of intrauterine inflammation were found than in elective CS: the prevalence of chorioamnionitis was higher (18 vs 4%, p = 0.02) and amniotic fluid concentration of IL-6 was higher (3.1 vs 0.37 ng/mL, p<0.001). Similar results were obtained for IL-8 (10.93 vs 0.96 ng/mL, p<0.001) and percentage of detectable TNF-alpha (50 vs 4%, p<0.001). CONCLUSIONS:This large cross-sectional study shows that spontaneous term delivery is characterized by histopathological signs of placenta inflammation and increased amniotic fluid proinflammatory cytokines

Challenges to adaptation: a fundamental concept for the shared socio-economic pathways and beyond

The framework for the new scenarios being developed for climate research calls for the development of a set of Shared Socioeconomic Pathways (SSPs), which are meant to differ in terms of their challenges to mitigation and challenges to adaptation. In order for the scenario process to fulfill its goals, the research and policy communities need to develop a shared understanding of these concepts. This paper focuses on challenges to adaptation. We begin by situating this new concept in the context of the rich literatures related to inter alia adaptation, vulnerability, and resilience. We argue that a proper characterization of challenges to adaptation requires a rich, exploration of the concept, which goes beyond mere description. This has a number of implications for the operationalization of the concept in the basic and extended versions of the SSPs. First, the elements comprising challenges to adaptation must include a wide range of socioeconomic and even some (non-climatic) biophysical factors. Second, careful consideration must be given to differences in these factors across scales, as well as cross-scale interactions. Third, any representation of the concept will require both quantitative and qualitative elements. The scenario framework offers the opportunity for the SSPs and full scenarios to be of greater value than has been the case in past exercises to both Integrated Assessment Modeling (IAM) and Impacts,Adaptation, and Vulnerability (IAV) researchers, but this will require a renegotiation of the traditional, primarily unidirectional relationship between the two communities