945 resultados para Ordered subsets – Expectation maximization (OS-EM)
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We characterize the weighted Hardy inequalities for monotone functions in Rn +. In dimension n = 1, this recovers the standard theory of Bp weights. For n > 1, the result was previously only known for the case p = 1. In fact, our main theorem is proved in the more general setting of partly ordered measure spaces.
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To study telomere length dynamics in hematopoietic cells with age, we analyzed the average length of telomere repeat sequences in diverse populations of nucleated blood cells. More than 500 individuals ranging in age from 0 to 90 yr, including 36 pairs of monozygous and dizygotic twins, were analyzed using quantitative fluorescence in situ hybridization and flow cytometry. Granulocytes and naive T cells showed a parallel biphasic decline in telomere length with age that most likely reflected accumulated cell divisions in the common precursors of both cell types: hematopoietic stem cells. Telomere loss was very rapid in the first year, and continued for more than eight decades at a 30-fold lower rate. Memory T cells also showed an initial rapid decline in telomere length with age. However, in contrast to naive T cells, this decline continued for several years, and in older individuals lymphocytes typically had shorter telomeres than did granulocytes. Our findings point to a dramatic decline in stem cell turnover in early childhood and support the notion that cell divisions in hematopoietic stem cells and T cells result in loss of telomeric DNA.
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After antigenic challenge, naive T lymphocytes enter a program of proliferation and differentiation during the course of which they acquire effector functions and may ultimately become memory cells. In humans, the pathways of effector and memory T-cell differentiation remain poorly defined. Here we describe the properties of 2 CD8+ T-lymphocyte subsets, RA+CCR7-27+28+ and RA+CCR7-27+28-, in human peripheral blood. These cells display phenotypic and functional features that are intermediate between naive and effector T cells. Like naive T lymphocytes, both subsets show relatively long telomeres. However, unlike the naive population, these T cells exhibit reduced levels of T-cell receptor excision circles (TRECs), indicating they have undergone additional rounds of in vivo cell division. Furthermore, we show that they also share effector-type properties. At equivalent in vivo replicative history, the 2 subsets express high levels of Fas/CD95 and CD11a, as well as increasing levels of effector mediators such as granzyme B, perforin, interferon gamma, and tumor necrosis factor alpha. Both display partial ex vivo cytolytic activity and can be found among cytomegalovirus-specific cytolytic T cells. Taken together, our data point to the presence of T cells with intermediate effector-like functions and suggest that these subsets consist of T lymphocytes that are evolving toward a more differentiated effector or effector-memory stage.
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Because self-reported health status [SRHS] is an ordered response variable, inequality measurement for SRHS data requires a numerical scale for converting individual responses into a summary statistic. The choice of scale is however problematic, since small variations in the numerical scale may reverse the ordering of a given pair of distributions of SRHS data in relation to conventional inequality indices such as the variance. This paper introduces a parametric family of inequality indices, founded on an inequality ordering proposed by Allison and Foster [Allison, R.A., Foster, J., 2004. Measuring health inequalities using qualitative data. Journal of Health Economics 23, 505-524], which satisfy a suitable invariance property with respect to the choice of numerical scale. Several key members of the parametric family are also derived, and an empirical application using data from the Swiss Health Survey illustrates the proposed methodology. [Authors]
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SUMMARY : The recognition by recipient T cells of the allograft major histocompatibility complex (MHC)mismatched antigens is the primary event that ultimately leads to rejection. In the transplantation setting, circulating alloreactive CD4+ T cells play a central role in the initiation and the coordination of the immune response and can initiate the rejection of an allograft via three distinct pathways: the direct, indirect and the recently described semi-direct pathway. However, the exact role of individual CD4+ T-cell subsets in the development of allograft rejection is not clearly defined. Furthermore, besides pathogenic effector T cells, a new subset of T cells with regulatory properties, the CD4+CD25+Foxp3+ (Treg) cells, has come under increased scrutiny over the last decade. The experiments presented in this thesis were designed to better define the phenotype and functional characteristics of CD4+ T-cell subsets and Treg cells in vitro and in vivo in a marine adoptive transfer and skin transplantation model. As Treg cells play a key role in the induction and maintenance of peripheral transplantation tolerance, we have explored whether donor-antigen specific Treg cells could be expanded in vitro. Here we describe a robust protocol for the ex-vivo generation and expansion of antigen-specific Treg cells, without loss of their characteristic phenotype and suppressive function. In our in vivo transplantation model, antigen-specific Treg cells induced donor-specific tolerance to skin allografts in lymphopenic recipients and significantly delayed skin graft rejection in wild-type mice in the absence of any other immunosuppression. Naïve and memory CD4+ T cells have distinct phenotypes, effector functions and in vivo homeostatsis, and thus may play different roles in anti-donor immunity after transplantation. We have analyzed in vitro and in vivo primary alloresponses of naïve and cross-reactive memory CD4+ T cells. We found that the CD4+CD45RBlo memory T-cell pool was heterogeneous and contained cells with regulatory potentials, both in the CD4+CD25+ and CD4+CD25- populations. CD4+ T cells capable of inducing strong primary alloreactive responses in vitro and rejection of a first allograft in vivo were mainly contained within the CD45RBhi naïve CD4+ T-cell compartment. Taken together, the work described in this thesis provides new insights into the mechanisms that drive allograft rejection or donor-specific transplantation tolerance. These results will help to optimise current clinical immunosuppressive regimens used after solid organ transplantation and design new immunotherapeutic strategies to prevent transplant rejection. RÉSUMÉ : ROLE DES SOUS-POPULATIONS DE CELLULES T DANS LE REJET DE GREFFE ET L'INDUCTION DE TOLERANCE EN TRANSPLANTATION La reconnaissance par les cellules T du receveur des alloantigènes du complexe majeur d'histocompatibilité (CMIT) présentés par une greffe allogénique, est le premier événement qui aboutira au rejet de l'organe greffé. Dans le contexte d'une transplantation, les cellules alloréactives T CD4+ circulantes jouent un rôle central dans l'initiation et la coordination de 1a réponse immune, et peuvent initier le rejet par 3 voies distinctes : la voie directe, indirecte et la voie servi-directe, plus récemment décrite. Toutefois, le rôle exact des sous-populations de cellules T CD4+ dans les différentes étapes menant au rejet d'une allogreffe n'est pas clairement établi. Par ailleurs, hormis les cellules T effectrices pathogéniques, une sous-population de cellules T ayant des propriétés régulatrices, les cellules T CD4+CD25+Foxp3+ (Treg), a été nouvellement décrite et est intensément étudiée depuis environ dix ans. Les expériences présentées dans cette thèse ont été planifiées afin de mieux définir le phénotype et les caractéristiques fonctionnels des sous-populations de cellules T CD4+ et des Treg in vitro et in vivo dans un modèle marin de transfert adoptif de cellules et de transplantation de peau. Comme les cellules Treg jouent un rôle clé dans l'induction et le maintien de la tolérance périphérique en transplantation, nous avons investigué la possibilité de multiplier in vitro des cellules Treg avec spécificité antigénique pour le donneur. Nous décrivons ici un protocole reproductible pour la génération et l'expansion ex-vivo de cellules Treg avec spécificité antigénique, sans perte de leur phénotype caractéristique et de leur fonction suppressive. Dans notre modèle in vivo de transplantation de peau, ces cellules Treg pouvaient induire une tolérance spécifique vis-à-vis du donneur chez des souris lymphopéniques, et, chez des souris normales non-lymphopéniques ces Treg ont permis de retarder significativement le rejet en l'absence de tout traitement immunosuppresseur. Les cellules T CD4+ naïves et mémoires se distinguent par leur phénotype, fonction effectrice et leur homéostasie in vivo, et peuvent donc moduler différemment la réponse immune contre le donneur après transplantation. Nous avons analysé in vitro et in vivo les réponses allogéniques primaires de cellules T CD4+ naïves et mémoires non-spécifiques (cross-réactives). Nos résultats ont montré que le pool de cellules T CD4+CD45RB'° mémoires était hétérogène et contenait des cellules avec un potentiel régulateur, aussi bien parmi la sous-population de cellules CD4+CD25+ que CD4+CD25+. Les cellules T CD4+ capables d'induire une alloréponse primaire intense in vitro et le rejet d'une première allogreffe in vivo étaient essentiellement contenues dans le pool de cellules T CD4+CD45RBhi naïves. En conclusion, le travail décrit dans cette thèse amène un nouvel éclairage sur les mécanismes responsables du rejet d'une allogreffe ou de l'induction de tolérance en transplantation. Ces résultats permettront d'optimaliser les traitements immunosuppresseurs utilisés en transplantation clinique et de concevoir des nouvelles stratégies irnmuno-thérapeutiques pour prévenir le rejet de greffe allogénique.
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The objective of this work was to verify the existence of a lethal locus in a eucalyptus hybrid population, and to quantify the segregation distortion in the linkage group 3 of the Eucalyptus genome. A E. grandis x E. urophylla hybrid population, which segregates for rust resistance, was genotyped with 19 microsatellite markers belonging to linkage group 3 of the Eucalyptus genome. To quantify the segregation distortion, maximum likelihood (ML) models, specific to outbreeding populations, were used. These models consider the observed marker genotypes and the lethal locus viability as parameters. The ML solutions were obtained using the expectation‑maximization algorithm. A lethal locus in the linkage group 3 was verified and mapped, with high confidence, between the microssatellites EMBRA 189 e EMBRA 122. This lethal locus causes an intense gametic selection from the male side. Its map position is 25 cM from the locus which controls the rust resistance in this population.
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Individuals with Down syndrome (DS) present important motor deficits that derive from altered motor development of infants and young children. DYRK1A, a candidate gene for DS abnormalities has been implicated in motor function due to its expression in motor nuclei in the adult brain, and its overexpression in DS mouse models leads to hyperactivity and altered motor learning. However, its precise role in the adult motor system, or its possible involvement in postnatal locomotor development has not yet been clarified. During the postnatal period we observed time-specific expression of Dyrk1A in discrete subsets of brainstem nuclei and spinal cord motor neurons. Interestingly, we describe for the first time the presence of Dyrk1A in the presynaptic terminal of the neuromuscular junctions and its axonal transport from the facial nucleus, suggesting a function for Dyrk1A in these structures. Relevant to DS, Dyrk1A overexpression in transgenic mice (TgDyrk1A) produces motor developmental alterations possibly contributing to DS motor phenotypes and modifies the numbers of motor cholinergic neurons, suggesting that the kinase may have a role in the development of the brainstem and spinal cord motor system.
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Tämä työ on tehty kansainväliselle metsäteollisuusyritykselle. Työn lähtökohtana oli tarve tutkia yrityksen mahdollisuuksia laajentaa toimintaansa uudelle markkinasegmentille, eläinruokapakkausmarkkinoille. Johtuen maailmanlaajuisesta eläinruoankulutuksen kasvusta, eläinruokapakkaukset ovat yritykselle mielenkiintoinen uusi markkina-alue. Onnistunut markkinoilletulo vaatii asiakastarpeiden ja -odotusten huomioimista tuotekehitys- ja markkinastrategian muodostamisessa. Tämän työn tavoitteena oli selvittää asiakkaiden odotuksia eläinruokapakkauksille, sekä mallintaa alalla vallitsevia ostoprosesseja. Asiakastarvetutkimus suunniteltiin perustuen kirjallisuuteen ja alustaviin markkina- ja asiakasanalyyseihin. Alustavat analyysit ovat tarpeellisia lähtötilanteen ja trendien selvittämiseksi. Itse tutkimus toteutettiin semi-konstruktoituna teemahaastatteluna. Haastateltavat edustivat USA:n ja Euroopan johtavia eläinruokavalmistajia ja pakkausten jatkojalostajia. Työn tuloksena saatiin yksityiskohtaista tietoa asiakkaiden odotuksista eläinruokapakkauksille, paperin ominaisuuksille ja paperitoimittajille. Lisäksi mallinnettiin ostoprosesseja paperitoimittajien, pakkausten jalostajien ja eläinruokavalmistajien välillä. Tulosten perusteella on analysoitu yrityksen mahdollisuuksia menestyä uudella markkinasegmentillä. Lisäksi työssä annettiin ehdotuksia tuotekehitys- ja markkinastrategian muodostamiseen.
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Advances in flow cytometry and other single-cell technologies have enabled high-dimensional, high-throughput measurements of individual cells as well as the interrogation of cell population heterogeneity. However, in many instances, computational tools to analyze the wealth of data generated by these technologies are lacking. Here, we present a computational framework for unbiased combinatorial polyfunctionality analysis of antigen-specific T-cell subsets (COMPASS). COMPASS uses a Bayesian hierarchical framework to model all observed cell subsets and select those most likely to have antigen-specific responses. Cell-subset responses are quantified by posterior probabilities, and human subject-level responses are quantified by two summary statistics that describe the quality of an individual's polyfunctional response and can be correlated directly with clinical outcome. Using three clinical data sets of cytokine production, we demonstrate how COMPASS improves characterization of antigen-specific T cells and reveals cellular 'correlates of protection/immunity' in the RV144 HIV vaccine efficacy trial that are missed by other methods. COMPASS is available as open-source software.
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Distortion risk measures summarize the risk of a loss distribution by means of a single value. In fuzzy systems, the Ordered Weighted Averaging (OWA) and Weighted Ordered Weighted Averaging (WOWA) operators are used to aggregate a large number of fuzzy rules into a single value. We show that these concepts can be derived from the Choquet integral, and then the mathematical relationship between distortion risk measures and the OWA and WOWA operators for discrete and finite random variables is presented. This connection offers a new interpretation of distortion risk measures and, in particular, Value-at-Risk and Tail Value-at-Risk can be understood from an aggregation operator perspective. The theoretical results are illustrated in an example and the degree of orness concept is discussed.
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A simple and effective route has been developed for the synthesis of bimodal (3.6 and 9.4 nm) mesoporous silica materials that have two ordered interconnected pore networks. Mesostructures have been prepared through the self assembly mechanism by using a mixture of polyoxyethylene fluoroalkyl ether and triblock copolymer as building block. The investigation of the RF8(EO)9/P123/water phase diagram evidences that in the considered surfactant range of concentrations, the system is micellar (L1). DLS measurements indicate that this micellar phase is composed of two types of micelles, the size of the first one at around 7.6 nm corresponds unambiguously to the pure fluorinated micelles. The second type of micelles at higher diameter consists of fluorinated micelles which have accommodated a weak fraction of P123 molecules. Thus, in this study the bimodal mesoporous silica are really templated by two kinds of micelles.
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Cellular immune responses are a critical part of the host's defense against intracellular bacterial infections. Immunity to Brucella abortus crucially depends on antigen-specific T cell-mediated activation of macrophages, which are the major effectors of cell-mediated killing of this organism. T lymphocytes that proliferate in response to B. abortus were characterized for phenotype and cytokine activity. Human, murine, and bovine T lymphocytes exhibited a type 1 cytokine profile, suggesting an analogous immune response in these different hosts. In vivo protection afforded by a particular cell type is dependent on the antigen presented and the mechanism of antigen presentation. Studies using MHC class I and class II knockout mice infected with B. abortus have demonstrated that protective immunity to brucellosis is especially dependent on CD8+ T cells. To target MHC class I presentation we transfected ex vivo a murine macrophage cell line with B. abortus genes and adoptively transferred them to BALB/c mice. These transgenic macrophage clones induced partial protection in mice against experimental brucellosis. Knowing the cells required for protection, vaccines can be designed to activate the protective T cell subset. Lastly, as a new strategy for priming a specific class I-restricted T cell response in vivo, we used genetic immunization by particle bombardment-mediated gene transfer
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Type 2 diabetes mellitus (T2D) is a metabolic disease with inflammation as an important pathogenic background. However, the pattern of immune cell subsets and the cytokine profile associated with development of T2D are unclear. The objective of this study was to evaluate different components of the immune system in T2D patients' peripheral blood by quantifying the frequency of lymphocyte subsets and intracellular pro- and anti-inflammatory cytokine production by T cells. Clinical data and blood samples were collected from 22 men (51.6±6.3 years old) with T2D and 20 nonsmoking men (49.4±7.6 years old) who were matched for age and sex as control subjects. Glycated hemoglobin, high-sensitivity C-reactive protein concentrations, and the lipid profile were measured by a commercially available automated system. Frequencies of lymphocyte subsets in peripheral blood and intracellular production of interleukin (IL)-4, IL-10, IL-17, tumor necrosis factor-α, and interferon-γ cytokines by CD3+ T cells were assessed by flow cytometry. No differences were observed in the frequency of CD19+ B cells, CD3+CD8+ and CD3+CD4+ T cells, CD16+56+ NK cells, and CD4+CD25+Foxp3+ T regulatory cells in patients with T2D compared with controls. The numbers of IL-10- and IL-17-producing CD3+ T cells were significantly higher in patients with T2D than in controls (P<0.05). The frequency of interferon-γ-producing CD3+ T cells was positively correlated with body mass index (r=0.59; P=0.01). In conclusion, this study shows increased numbers of circulating IL-10- and IL-17-producing CD3+ T cells in patients with T2D, suggesting that these cytokines are involved in the immune pathology of this disease.
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Ordered probit regression was used to analyze data of sensory acceptance tests designed to study the effect of brand name on the acceptability of beer samples. Eight different brands of Pilsen beer were evaluated by 101 consumers in two sessions of acceptance tests: blind evaluation and brand information test. Ordered probit regression, although a relatively sophisticated technique compared to others used to analyze sensory data, was chosen to enable the observation of consumers' behavior using graphical interpretations of estimated probabilities plotted against hedonic scales. It can be concluded that brands B, C, and D had a positive effect on the sensory acceptance of the product, whereas brands A, F, G, and H had a negative influence on consumers' evaluation of the samples. On the other hand, brand E had little influence on consumers' assessment.