962 resultados para Turn Mimetics
Resumo:
Chloroquine has been the mainstay of malaria chemotherapy for the past five decades, but resistance is now widespread. Pyrimethamine or proguanil form an important component of some alternate drug combinations being used for treatment of uncomplicated Plasmodium falciparum infections in areas of chloroquine resistance. Both pyrimethamine and proguanil are dihydrofolate reductase (DHFR) inhibitors, the proguanil acting primarily through its major metabolite cycloguanil. Resistance to these drugs arises due to specific point mutations in the dhfr gene. Cross resistance between cycloguanil and pyrimethamine is not absolute. It is, therefore, important to investigate mutation rates in P. falciparum for pyrimethamine and proguanil so that DHFR inhibitor with less mutation rate is favored in drug combinations. Hence, we have compared mutation rates in P. falciparum genome for pyrimethamine and cycloguanil. Using erythrocytic stages of P. falciparum cultures, progressively drug resistant lines were selected in vitro and comparing their RFLP profile with a repeat sequence. Our finding suggests that pyrimethamine has higher mutation rate compared to cycloguanil. It enhances the degree of genomic polymorphism leading to diversity of natural parasite population which in turn is predisposes the parasites for faster selection of resistance to some other antimalarial drugs.
Resumo:
Given positive integers n and m, we consider dynamical systems in which n copies of a topological space is homeomorphic to m copies of that same space. The universal such system is shown to arise naturally from the study of a C*-algebra we denote by Om;n, which in turn is obtained as a quotient of the well known Leavitt C*-algebra Lm;n, a process meant to transform the generating set of partial isometries of Lm;n into a tame set. Describing Om;n as the crossed-product of the universal (m; n) -dynamical system by a partial action of the free group Fm+n, we show that Om;n is not exact when n and m are both greater than or equal to 2, but the corresponding reduced crossed-product, denoted Or m;n, is shown to be exact and non-nuclear. Still under the assumption that m; n &= 2, we prove that the partial action of Fm+n is topologically free and that Or m;n satisfies property (SP) (small projections). We also show that Or m;n admits no finite dimensional representations. The techniques developed to treat this system include several new results pertaining to the theory of Fell bundles over discrete groups.
Resumo:
En el nostre projecte, considerem un escenari urbà o interurbà on persones amb dispositius mòbils (smartphones) o vehicles equipats amb interfícies de comunicació, estan interessats en compartir fitxers entre ells o descarregar-los al creuar Punts d’Accés (APs) propers a la carretera. Estudiem la possibilitat d’utilizar la cooperació en les trobades casuals entre nodes per augmentar la velocitat de descàrrega global. Amb aquest objectiu, plantejem algoritmes per a la selecció de quins paquets, per a quins destins i quins transportistes s’escullen en cada moment. Mitjançant extenses simulacions, mostrem com les cooperacions carry&forward dels nodes augmenten significativament la velocitat de descàrrega dels usuaris, i com aquest resultat es manté per a diversos patrons de mobilitat, col•locacions d'AP i càrregues de la xarxa. Per altra banda, aparells com els smartphones, on la targeta de WiFi està encesa contínuament, consumeixen l'energia de la bateria en poques hores. En molts escenaris, una targeta WiFi sempre activa és poc útil, perque sovint no hi ha necessitat de transmissió o recepció. Aquest fet es veu agreujat en les Delay Tolerant Networks (DTN), on els nodes intercanvien dades quan es creuen i en tenen l’oportunitat. Les tècniques de gestió de l’estalvi d’energia permeten extendre la duració de les bateries. El nostre projecte analitza els avantatges i inconvenients que apareixen quan els nodes apaguen períodicament la seva targeta wireless per a estalviar energia en escenaris DTN. Els nostres resultats mostren les condicions en que un node pot desconnectar la bateria sense afectar la probabilitat de contacte amb altres nodes, i les condicions en que aquesta disminueix. Per exemple, es demostra que la vida del node pot ser duplicada mantenint la probabilitat de contacte a 1. I que aquesta disminueix ràpidament en intentar augmentar més la vida útil.
Resumo:
El sistema nerviós central (SNC) i el sistema immunitari (SI) estan estretament connectats. Es produeixen nombroses alteracions en el sistema immunitari després de la isquèmia i la inflamació es reconeix com una de les principals causes de la progressió de la lesió isquèmica. És molt important determinar el paper de les diferents cèl•lules implicades en la resposta immunitària i inflamatòria després de la isquèmia i el perfil de citocines que s’alliberen. A partir de l’estudi de les diferents poblacions de leucòcits en sang circulant després de la isquèmia, hem determinat que la subpoblació de monòcits (CD43high/CD11bhigh) augmenta a 48h de manera proporcional al volum d’infart. Aquesta població està formada per dos subtipus descrits de monòcits, els no clàssics (CD43high/Ly6C-) i els intermedis (CD43high/Ly6Cdim), i sembla expressar un perfil de citocines anti-inflamatòries així com una major capacitat fagocítica. Per altra banda, observem la presència de CD43 en el cervell i la seva degradació a 4 dies després de la isquèmia. També s’observa l’aparició de la fracció soluble del CD43 en el parènquima cerebral després del trencament de la barrera hematoencefàlica. Addicionalment, hem estudiat com s’alteren els canvis a nivell immunològic en ratolins deficients en CD69 i hem observat una pitjor progressió del volum d’infart en els animals CD69KO. A més a més hem volgut esbrinar el paper dels limfòcits utilitzant ratolins RAG (-/-) que tenen infarts més petits que els WT, però quan aquests careixen de CD69, tenen infarts significativament més grans. En l’estudi del procés inflamatori en la isquèmica, hem treballat amb ratolins deficient en ApoE i IL10. Pel que fa als ratolins ApoE (-/-), observem que tenen un volum d’infart més gran a les 24h i que es manté fins als 4 dies, i proposem que NFkB pot tenir un paper molt rellevant en aquest procés. Pel que fa a la IL-10, els animals deficients en aquesta citocina presenten un volum d’infart major i una expressió de citocines proinflamatòries més alt. A més a més, els ratolins IL10 KO presenten uns nivells de IL-12 més elevats de manera basal, i proposem que això és degut a la falta de la IL-10 per a inhibir la via.
Resumo:
The choice of sample preparation protocol is a critical influential factor for isoelectric focusing which in turn affects the two-dimensional gel result in terms of quality and protein species distribution. The optimal protocol varies depending on the nature of the sample for analysis and the properties of the constituent protein species (hydrophobicity, tendency to form aggregates, copy number) intended for resolution. This review explains the standard sample buffer constituents and illustrates a series of protocols for processing diverse samples for two-dimensional gel electrophoresis, including hydrophobic membrane proteins. Current methods for concentrating lower abundance proteins, by removal of high abundance proteins, are also outlined. Finally, since protein staining is becoming increasingly incorporated into the sample preparation procedure, we describe the principles and applications of current (and future) pre-electrophoretic labelling methods.
Resumo:
The article is composed of two sections. The first one is a critical review of the three main alternative indices to GDP which were proposed in the last decades – the Human Development Index (HDI), the Genuine Progress Indicator (GPI), and the Happy Planet Index (HPI) – which is made on the basis of conceptual foundations, rather than looking at issues of statistical consistency or mathematical refinement as most of the literature does. The pars construens aims to propose an alternative measure, the composite wealth index, consistent with an approach to development based on the notion of composite wealth, which is in turn derived from an empirical common sense criterion. Arguably, this approach is suitable to be conveyed into an easily understandable and coherent indicator, and thus appropriate to track development in its various dimensions: simple in its formulation, the wealth approach can incorporate social and ecological goals without significant alterations in conceptual foundations, while reducing to a minimum arbitrary weighting.
Resumo:
Discovered in 1909, Chagas disease was progressively shown to be widespread throughout Latin America, affecting millions of rural people with a high impact on morbidity and mortality. With no vaccine or specific treatment available for large-scale public health interventions, the main control strategy relies on prevention of transmission, principally by eliminating the domestic insect vectors and control of transmission by blood transfusion. Vector control activities began in the 1940s, initially by means of housing improvement and then through insecticide spraying following successful field trials in Brazil (Bambui Research Centre), with similar results soon reproduced in São Paulo, Argentina, Venezuela and Chile. But national control programmes only began to be implemented after the 1970s, when technical questions were overcome and the scientific demonstration of the high social impact of Chagas disease was used to encourage political determination in favour of national campaigns (mainly in Brazil). Similarly, large-scale screening of infected blood donors in Latin America only began in the 1980s following the emergence of AIDS. By the end of the last century it became clear that continuous control in contiguous endemic areas could lead to the elimination of the most highly domestic vector populations - especially Triatoma infestans and Rhodnius prolixus - as well as substantial reductions of other widespread species such as T. brasiliensis, T. sordida, and T. dimidiata, leading in turn to interruption of disease transmission to rural people. The social impact of Chagas disease control can now be readily demonstrated by the disappearance of acute cases and of new infections in younger age groups, as well as progressive reductions of mortality and morbidity rates in controlled areas. In economic terms, the cost-benefit relationship between intervention (insecticide spraying, serology in blood banks) and the reduction of Chagas disease (in terms of medical and social care and improved productivity) is highly positive. Effective control of Chagas disease is now seen as an attainable goal that depends primarily on maintaining political will, so that the major constraints involve problems associated with the decentralisation of public health services and the progressive political disinterest in Chagas disease. Counterbalancing this are the political and technical cooperation strategies such as the "Southern Cone Initiative" launched in 1991. This international approach, coordinated by PAHO, has been highly successful, already reaching elimination of Chagas disease transmission in Uruguay, Chile, and large parts of Brazil and Argentina. The Southern Cone Initiative also helped to stimulate control campaigns in other countries of the region (Paraguay, Bolivia, Peru) which have also reached tangible regional successes. This model of international activity has been shown to be feasible and effective, with similar initiatives developed since 1997 in the Andean Region and in Central America. At present, Mexico and the Amazon Region remain as the next major challenges. With consolidation of operational programmes in all endemic countries, the future focus will be on epidemiological surveillance and care of those people already infected. In political terms, the control of Chagas disease in Latin America can be considered, so far, as a victory for international scientific cooperation, but will require continuing political commitment for sustained success.
Resumo:
Mediante el presente documento se pretende describir el proceso de creación de una herramienta de tipo CMS (Gestor de contenidos). Concretamente, se desarrollará una herramienta que permita al usuario crear su propio sitio web sin necesidad de tener conocimientos de programación. Debido a la gran variedad de sitios web tanto en su forma como en su contenido y ante la imposibilidad de abarcar todo el espectro desde la primera versión del producto, se centrarán los esfuerzos en obtener una aplicación sencilla pero funcional y, sobretodo, escalable, para que mediante futuras actualizaciones se puedan ir incrementando sus posibilidades y capacidad.
Resumo:
The National Health Strategy “Quality and Fairness, Health System for You” states“ a key objective of the human resource framework is to develop and explicitly value staff at all levels of the health system. This in turn benefits service users.” The strategy explicitly states that one of its initiatives was “to introduce the grade of Health Care Assistant (HCA) as a member of healthcare teams to assist and support nurses and midwives. A national six month training programme for Health Care Assistants to commence at the end of November 2001. Seventeen pilot programmes to be delivered by the health services in conjunction with the Further Education Training Awards Council (FETAC)”.
Resumo:
Apart from several growth factors which play a crucial role in the survival and development of the central and peripheral nervous systems, thyroid hormones can affect different processes involved in the differentiation and maturation of neurons. The present study was initiated to determine whether triiodothyronine (T3) affects the survival and neurite outgrowth of primary sensory neurons in vitro. Dorsal root ganglia (DRG) from 19-day-old embryos or newborn rats were plated in explant or dissociated cell cultures. The effect of T3 on neuron survival was tested, either in mixed DRG cell cultures, where neurons grow with non-neuronal cells, or in neuron-enriched cultures where non-neuronal cells were eliminated at the outset. T3, in physiological concentrations, promoted the growth of neurons in mixed DRG cell cultures as well as in neuron-enriched cultures without added nerve growth factor (NGF). Since neuron survival in neuron-enriched cultures cannot be promoted by endogenous neurotrophic factors synthesized by non-neuronal cells, the increased number of surviving neurons was due to a direct trophic action of T3. Another trophic effect was revealed in this study: T3 sustained the neurite outgrowth of sensory neurons in DRG explants. The stimulatory effect of T3 on nerve fibre outgrowth was considerably reduced when non-neuronal cell proliferation was inhibited by the antimitotic agent cytosine arabinoside, and was completely suppressed when the great majority of non-neuronal cells were eliminated in neuron-enriched cultures. These results indicate that the stimulatory effect of T3 on neurite outgrowth is mediated through non-neuronal cells. It is conceivable that T3 up-regulates Schwann cell expression of a neurotrophic factor, which in turn stimulates axon growth of sensory neurons. Together, these results demonstrate that T3 promotes both survival and neurite outgrowth of primary sensory neurons in DRG cell cultures. The trophic actions of T3 on neuron survival and neurite outgrowth operate under two different pathways.
Resumo:
Résumé Régulation de l'expression de la Connexin36 dans les cellules sécrétrices d'insuline La communication intercellulaire est en partie assurée via des jonctions communicantes de type "gap". Dans la cellule ß pancréatique, plusieurs observations indiquent que le couplage assuré par des jonctions gap formées parla Connexine36 (Cx36) est impliqué dans le contrôle de la sécrétion de l'insuline. De plus, nous avons récemment démontré qu'un niveau précis d'expression de la Cx36 est nécessaire pour maintenir une bonne coordination de l'ensemble des cellules ß, et permettre ainsi une sécrétion synchrone et contrôlée d'insuline. Le développement du diabète et du syndrome métabolique est partiellement dû à une altération de la capacité des cellules ß à sécréter de l'insuline en réponse à une augmentation de la glycémie. Cette altération est en partie causée par l'augmentation prolongée des taux circulant de glucose, mais aussi de lipides, sous la forme d'acides gras libres, et de LDL (Low Density Lipoproteins), particules assurant le transport des acides gras et du cholestérol dans le sang. Nous avons étudié la régulation de l'expression de la Cx36 dans différentes conditions reflétant la physiopathologie du diabète de type 2 et du syndrome métabolique et démontré qu'une exposition prolongée à des concentrations élevées de glucose, de LDL, ainsi que de palmitate (acide gras saturé le plus abondant dans l'organisme), inhibent l'expression de la Cx36 dans les cellules ß. Cette inhibition implique l'activation de la PKA (Proteine Kinase A), qui stimule à son tour l'expression du facteur de transcription ICER-1 (Inductible cAMP Early Repressor-1). Ce puissant répresseur se fixe spécifiquement sur un motif CRE (cAMP Response Element), situé dans le promoteur du gène de la Cx36, inhibant ainsi son expression. Nous avons de plus démontré que des cytokines pro-inflammatoires, qui pourraient contribuer au développement du diabète, inhibent également l'expression de la Cx36. Cependant, les cytokines agissent indépendamment du répresseur ICER-1, mais selon un mécanisme requérant l'activation de l'AMPK (AMP dependant protein kinase). Sachant qu'un contrôle précis des niveaux d'expression de la Cx36 est un élément déterminant pour une sécrétion optimale de l'insuline, nos résultats suggèrent que la Cx36 pourrait être impliquée dans l'altération de la sécrétion de l'insuline contribuant à l'apparition du diabète de type 2. Summary A particular way by which cells communicate with each other is mediated by gap junctions, transmembrane structures providing a direct pathway for the diffusion of small molecules between adjacent cells. Gap junctional communication is required to maintain a proper functioning of insulin-secreting ß-cells. Moreover, the expression levels of connexin36 (Cx36), the sole gap junction protein expressed in ß-cells, are critical in maintaining glucose-stimulated insulin secretion. Chronic hyperglycemia and hyperlipidemia exert deleterious effects on insulin secretion and may contribute to the progressive ß-cell failure linked to the development of type 2 diabetes and metabolic syndrome. Since modulations of the Cx36 levels might impair ß-cell function, the general aim of this work was to elucidate wether elevated levels of glucose and lipids affect Cx36 expression. The first part of this work was dedicated to the study of the effect of high glucose concentrations on Cx36 expression. We demonstrated that glucose transcriptionally down-regulates the expression of Cx36 in insulin-secreting cells through activation of the protein kinase A (PKA), which in turn stimulates the expression of the inducible cAMP early repressor-1 (ICER-1). This repressor binds to a highly conserved cAMP response element (CRE) located in the Cx36 promoter, thereby inhibiting Cx36 expression. The second part of this thesis consisted in studying the effects of sustained exposure to free fatty acids (FFA) and human lipoproteins on Cx36 levels. The experiments revealed that the most abundant FFA, palmitate, as well as the atherogenic low density lipoproteins (LDL), also stimulate ICER-1 expression, resulting in Cx36 down-regulation. Finally, the third part of the work focused on the consequences of long-term exposure to proinflammatory cytokines on Cx36 content. Interleukin-1 ß (IL-1 ß) inhibits Cx36 expression and its effect is potentialized by tumor necrosis factor α (TNFα) and interferon γ (IFNγ). We further unveiled that the cytokines effect on Cx36 levels requires activation of the AMP dependent protein kinase (AMPK). Prolonged exposures to glucose, palmitate, LDL, and pro-inflammatory cytokines have all been proposed to contribute to the development of diabetes and metabolic syndrome. Since Cx36 expression levels are critical to maintain ß-cell function, Cx36 down-regulation by glucose, lipids, and cytokines might participate to the ß-cell failure associated with diabetes development.
Resumo:
Preservation of beta cell against apoptosis is one of the therapeutic benefits of the glucagon-like peptide-1 (GLP1) antidiabetic mimetics for preserving the functional beta cell mass exposed to diabetogenic condition including proinflammatory cytokines. The mitogen activated protein kinase 10 also called c-jun amino-terminal kinase 3 (JNK3) plays a protective role in insulin-secreting cells against death caused by cytokines. In this study, we investigated whether the JNK3 expression is associated with the protective effect elicited by the GLP1 mimetic exendin 4. We found an increase in the abundance of JNK3 in isolated human islets and INS-1E cells cultured with exendin 4. Induction of JNK3 by exendin 4 was associated with an increased survival of INS-1E cells. Silencing of JNK3 prevented the cytoprotective effect of exendin 4 against apoptosis elicited by culture condition and cytokines. These results emphasize the requirement of JNK3 in the antiapoptotic effects of exendin 4.
Resumo:
Adjuvants have been shown since many years to have an important role in enhancing the immune responses against the co-administered antigens used as vaccines. The continuous study of the mechanism of action of adjuvants is necessary to develop further safe and efficacious vaccines. Complete Freund's adjuvant (CFA) is currently in use as adjuvant to induce some autoimmune diseases in murine models, therefore the study of the mechanisms involved in the generation of the related immune responses could be instrumental for the understanding of the induction of inflammatory Thl7 responses. In the present work, we showed in C57B1/6 mice that CFA peripheral administration induces very early, at 6 h, a potent influx of CDllb+ cells, mainly neutrophils (CD11b+Ly6GhighLy6Cint) and monocytes (CD11b+Ly6GlowLy6Chigh), in the draining lymph node. By investigating the route by which neutrophils reach the lymph node we observed that, around 20% of them arrive from the afferent lymph and the majority stains positive for Mycobacterium tuberculosis. We also observed a correlation between the influx of neutrophils and an increase in IL-23 and IL-Ιβ, together with several inflammatory chemokines, in the draining lymph node. Concomitantly, we detected the expression of the IL-23 receptor on CDllc+ DCs. Moreover, we confirmed the ability of murine neutrophils to express IL-23 both, in vitro by stimulating bone-marrow extracted PMNs with Mycobacterium tuberculosis, and on total cells from draining lymph node by immunohistochemistry. We also observed by in vivo priming a reduction in the percentage of IFN-γ and CXCR3 expressing Τ cells upon depletion of neutrophils. Altogether, we show that upon stimulation from the periphery, the draining lymph node undergo changes in cytokine/chemokine production leading to the recruitment of different leukocytes subpopulations. Here we show that CFA induces a rapid influx of neutrophils which are responsible for the production of IL-23 that in turn influences the generation of Τ helper cells.
Resumo:
In mammals, many aspects of metabolism are under circadian control. At least in part, this regulation is achieved by core-clock or clock-controlled transcription factors whose abundance and/or activity oscillate during the day. The clock-controlled proline- and acidic amino acid-rich domain basic leucine zipper proteins D-site-binding protein, thyrotroph embryonic factor, and hepatic leukemia factor have previously been shown to participate in the circadian control of xenobiotic detoxification in liver and other peripheral organs. Here we present genetic and biochemical evidence that the three proline- and acidic amino acid-rich basic leucine zipper proteins also play a key role in circadian lipid metabolism by influencing the rhythmic expression and activity of the nuclear receptor peroxisome proliferator-activated receptor α (PPARα). Our results suggest that, in liver, D-site-binding protein, hepatic leukemia factor, and thyrotroph embryonic factor contribute to the circadian transcription of genes specifying acyl-CoA thioesterases, leading to a cyclic release of fatty acids from thioesters. In turn, the fatty acids act as ligands for PPARα, and the activated PPARα receptor then stimulates the transcription of genes encoding proteins involved in the uptake and/or metabolism of lipids, cholesterol, and glucose metabolism.
Resumo:
Numerous recent reports by non-governmental organisations (NGOs), academics and international organisations have focused on so-called 'climate refugees'. This article examines the turn from a discourse of 'climate refugees', in which organisations perceive migration as a failure of both mitigation and adaptation to climate change, to one of 'climate migration', in which organisations promote migration as a strategy of adaptation. Its focus is the promotion of climate migration management, and it explores the trend of these discourses through two sections. First, it provides an empirical account of the two discourses, emphasising the differentiation between them. It then focuses on the discourse of climate migration, its origins, extent and content, and the associated practices of 'migration management'. The second part argues that the turn to the promotion of 'climate migration' should be understood as a way to manage the insecurity created by climate change. However, international organisations enacts this management within the forms of neoliberal capitalism, including the framework of governance. Therefore, the promotion of 'climate migration' as a strategy of adaptation to climate change is located within the tendencies of neoliberalism and the reconfiguration of southern states' sovereignty through governance.