784 resultados para Class switch recombination
Resumo:
Experimental autoimmune myocarditis (EAM) is a CD4(+) T-cell-mediated model of human inflammatory dilated cardiomyopathies. Heart-specific CD4(+) T-cell activation is dependent on autoantigens presented by MHC class II (MHCII) molecules expressed on professional APCs. In this study, we addressed the role of inflammation-induced MHCII expression by cardiac nonhematopoietic cells on EAM development. EAM was induced in susceptible mice lacking inducible expression of MHCII molecules on all nonhematopoietic cells (pIV-/- K14 class II transactivator (CIITA) transgenic (Tg) mice) by immunization with α-myosin heavy chain peptide in CFA. Lack of inducible nonhematopoietic MHCII expression in pIV-/- K14 CIITA Tg mice conferred EAM resistance. In contrast, cardiac pathology was induced in WT and heterozygous mice, and correlated with elevated cardiac endothelial MHCII expression. Control mice with myocarditis displayed an increase in infiltrating CD4(+) T cells and in expression of IFN-γ, which is the major driver of nonhematopoietic MHCII expression. Mechanistically, IFN-γ neutralization in WT mice shortly before disease onset resulted in reduced cardiac MHCII expression and pathology. These findings reveal a previously overlooked contribution of IFN-γ to induce endothelial MHCII expression in the heart and to progress cardiac pathology during myocarditis.
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NLRC5, a member of the NOD-like receptor (NLR) protein family, has recently been characterized as the master transcriptional regulator of MHCI molecules in lymphocytes, in which it is highly expressed. However, its role in activated dendritic cells (DCs), which are instrumental to initiate T cell responses, remained elusive. We show in this study that, following stimulation of DCs with inflammatory stimuli, not only did NLRC5 level increase, but also its importance in directing MHCI transcription. Despite markedly reduced mRNA and intracellular H2-K levels, we unexpectedly observed nearly normal H2-K surface display in Nlrc5(-/-) DCs. Importantly, this discrepancy between a strong intracellular and a mild surface defect in H2-K levels was observed also in DCs with H2-K transcription defects independent of Nlrc5. Hence, alongside with demonstrating the importance of NLRC5 in MHCI transcription in activated DCs, we uncover a general mechanism counteracting low MHCI surface expression. In agreement with the decreased amount of neosynthesized MHCI, Nlrc5(-/-) DCs exhibited a defective capacity to display endogenous Ags. However, neither T cell priming by endogenous Ags nor cross-priming ability was substantially affected in activated Nlrc5(-/-) DCs. Altogether, these data show that Nlrc5 deficiency, despite significantly affecting MHCI transcription and Ag display, is not sufficient to hinder T cell activation, underlining the robustness of the T cell priming process by activated DCs.
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Identification of CD8+ cytotoxic T lymphocyte (CTL) epitopes has traditionally relied upon testing of overlapping peptide libraries for their reactivity with T cells in vitro. Here, we pursued deep ligand sequencing (DLS) as an alternative method of directly identifying those ligands that are epitopes presented to CTLs by the class I human leukocyte antigens (HLA) of infected cells. Soluble class I HLA-A*11:01 (sHLA) was gathered from HIV-1 NL4-3-infected human CD4+ SUP-T1 cells. HLA-A*11:01 harvested from infected cells was immunoaffinity purified and acid boiled to release heavy and light chains from peptide ligands that were then recovered by size-exclusion filtration. The ligands were first fractionated by high-pH high-pressure liquid chromatography and then subjected to separation by nano-liquid chromatography (nano-LC)–mass spectrometry (MS) at low pH. Approximately 10 million ions were selected for sequencing by tandem mass spectrometry (MS/MS). HLA-A*11:01 ligand sequences were determined with PEAKS software and confirmed by comparison to spectra generated from synthetic peptides. DLS identified 42 viral ligands presented by HLA-A*11:01, and 37 of these were previously undetected. These data demonstrate that (i) HIV-1 Gag and Nef are extensively sampled, (ii) ligand length variants are prevalent, particularly within Gag and Nef hot spots where ligand sequences overlap, (iii) noncanonical ligands are T cell reactive, and (iv) HIV-1 ligands are derived from de novo synthesis rather than endocytic sampling. Next-generation immunotherapies must factor these nascent HIV-1 ligand length variants and the finding that CTL-reactive epitopes may be absent during infection of CD4+ T cells into strategies designed to enhance T cell immunity.
Resumo:
The Class IIa histone deacetylases (HDAC)4 and HDAC5 play a role in neuronal survival and behavioral adaptation in the CNS. Phosphorylation at 2/3 N-terminal sites promote their nuclear export. We investigated whether non-canonical signaling routes to Class IIa HDAC export exist because of their association with the co-repressor Silencing Mediator Of Retinoic And Thyroid Hormone Receptors (SMRT). We found that, while HDAC5 and HDAC4 mutants lacking their N-terminal phosphorylation sites (HDAC4(MUT), HDAC5(MUT)) are constitutively nuclear, co-expression with SMRT renders them exportable by signals that trigger SMRT export, such as synaptic activity, HDAC inhibition, and Brain Derived Neurotrophic Factor (BDNF) signaling. We found that SMRT's repression domain 3 (RD3) is critical for co-shuttling of HDAC5(MUT), consistent with the role for this domain in Class IIa HDAC association. In the context of BDNF signaling, we found that HDAC5(WT), which was more cytoplasmic than HDAC5(MUT), accumulated in the nucleus after BDNF treatment. However, co-expression of SMRT blocked BDNF-induced HDAC5(WT) import in a RD3-dependent manner. In effect, SMRT-mediated HDAC5(WT) export was opposing the BDNF-induced HDAC5 nuclear accumulation observed in SMRT's absence. Thus, SMRT's presence may render Class IIa HDACs exportable by a wider range of signals than those which simply
Resumo:
The role of grammatical class in lexical access and representation is still not well understood. Grammatical effects obtained in picture-word interference experiments have been argued to show the operation of grammatical constraints during lexicalization when syntactic integration is required by the task. Alternative views hold that the ostensibly grammatical effects actually derive from the coincidence of semantic and grammatical differences between lexical candidates. We present three picture-word interference experiments conducted in Spanish. In the first two, the semantic relatedness (related or unrelated) and the grammatical class (nouns or verbs) of the target and the distracter were manipulated in an infinitive form action naming task in order to disentangle their contributions to verb lexical access. In the third experiment, a possible confound between grammatical class and semantic domain (objects or actions) was eliminated by using action-nouns as distracters. A condition in which participants were asked to name the action pictures using an inflected form of the verb was also included to explore whether the need of syntactic integration modulated the appearance of grammatical effects. Whereas action-words (nouns or verbs), but not object-nouns, produced longer reaction times irrespective of their grammatical class in the infinitive condition, only verbs slowed latencies in the inflected form condition. Our results suggest that speech production relies on the exclusion of candidate responses that do not fulfil task-pertinent criteria like membership in the appropriate semantic domain or grammatical class. Taken together, these findings are explained by a response-exclusion account of speech output. This and alternative hypotheses are discussed.
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We have developed a practical exercise for undergraduate students whose main aim is to identify, using genetic crosses, a pair of D. melanogaster mutations (miniature and singed). Each student receives a vial with the problem strain containing two unknown mutations. The first step is to observe and describe both mutations. Then, the students carry out genetic crosses between mutant and normal strains: (P) ♀ mutant strain × ♂ normal strain (P) ♀ normal strain × ♂ mutant strain A different offspring is expected in these crosses: in the first one we will obtain normal females and m sn males, whereas in the second all individuals will present normal phenotype. It is possible to deduce that both are sex linked mutations. With this information and to simplify the amount of work, only F1 individuals from the first cross will be used (m+sn+ / m sn × m sn / Y chrom.) to obtain the F2 generation. By counting the number of miniature (recombinant type), singed (recombinant type), miniature-singed (parental type) and normal (parental type) flies it is possible to estimate the recombination frequency between both genes. Knowing the phenotype, their chromosomal location (X chromosome) and the genetic distance between both mutations, it is possible to identify them by finding all this information in a Drosophila melanogaster genetic map. Additionally, a statistical analysis can be carried out to compare the number of expected F2 individuals with those observed in the experiment. As the distance between both genes is 15.1 m.u., then the expected percentages for each phenotype would be: normal (42.45%), miniature-signed (42.45%), miniature (7.55%) and singed (7.55%). Multiplying the frequency of each class by the total number of individuals obtained in the F2 it is possible to estimate the expected number of flies for each class. Finally, a χ2 test can be computed to ascertain whether there are significant differences between expected and observed number of individuals.
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This report outlines the discovery, the design and development of new compounds, and, structure-activity relationships for this drug category. Updated approaches to planned syntheses of new worthy ACE-inhibitors are also exploited.
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Sixteen dialkylphosphorylhydrazones were synthesized by condensation of phosphorylhydrazines with substituted isatins. Products were characterized by FTIR, ¹H-NMR, 13C-NMR, and 31P-NMR. Fungicidal activities of these compounds against Rhizoctonia solani and Fusarium oxysporum were also evaluated. Some compounds inhibited the growth of Rhizoctonia solani and Fusarium oxysporum by 43% and 51%, respectively. These compounds exhibited no effects on germination of lettuce seeds (Lactuca sativa L).
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This report describes a simple, inexpensive and highly effective instructional model based on the use of a tablet device to enable the real-time projection of the instructor's digitally handwritten annotations to teach chemistry in undergraduate courses. The projection of digital handwriting allows the instructor to build, present and adapt the class contents in a dynamic fashion and to save anything that is annotated or displayed on the screen for subsequent sharing with students after each session. This method avoids the loss of continuity and information that often occurs when instructors switch between electronic slides and white/chalk board during lessons. Students acknowledged that this methodology allows them to follow the instructor's cognitive process and the progressive development of contents during lectures as the most valuable aspect of the implemented instructional model.
Resumo:
Min avhandling behandlar hur oordnade material leder elektrisk ström. Bland materialen som studeras finns ledande polymerer, d.v.s. plaster som leder ström, och mer allmänt organiska halvledare. Av de här materialen har man kunnat bygga elektroniska komponenter, och man hoppas på att kunna trycka hela kretsar av organiska material. För de här tillämpningarna är det viktigt att förstå hur materialen själva leder elektrisk ström. Termen oordnade material syftar på material som saknar kristallstruktur. Oordningen gör att elektronernas tillstånd blir lokaliserade i rummet, så att en elektron i ett visst tillstånd är begränsad t.ex. till en molekyl eller ett segment av en polymer. Det här kan jämföras med kristallina material, där ett elektrontillstånd är utspritt över hela kristallen (men i stället har en väldefinierad rörelsemängd). Elektronerna (eller hålen) i det oordnade materialet kan röra sig genom att tunnelera mellan de lokaliserade tillstånden. Utgående från egenskaperna för den här tunneleringsprocessen, kan man bestämma transportegenskaperna för hela materialet. Det här är utgångspunkten för den så kallade hopptransportmodellen, som jag har använt mig av. Hopptransportmodellen innehåller flera drastiska förenklingar. Till exempel betraktas elektrontillstånden som punktformiga, så att tunneleringssannolikheten mellan två tillstånd endast beror på avståndet mellan dem, och inte på deras relativa orientation. En annan förenkling är att behandla det kvantmekaniska tunneleringsproblemet som en klassisk process, en slumpvandring. Trots de här grova approximationerna visar hopptransportmodellen ändå många av de fenomen som uppträder i de verkliga materialen som man vill modellera. Man kan kanske säga att hopptransportmodellen är den enklaste modell för oordnade material som fortfarande är intressant att studera. Man har inte hittat exakta analytiska lösningar för hopptransportmodellen, därför använder man approximationer och numeriska metoder, ofta i form av datorberäkningar. Vi har använt både analytiska metoder och numeriska beräkningar för att studera olika aspekter av hopptransportmodellen. En viktig del av artiklarna som min avhandling baserar sig på är att jämföra analytiska och numeriska resultat. Min andel av arbetet har främst varit att utveckla de numeriska metoderna och applicera dem på hopptransportmodellen. Därför fokuserar jag på den här delen av arbetet i avhandlingens introduktionsdel. Ett sätt att studera hopptransportmodellen numeriskt är att direkt utföra en slumpvandringsprocess med ett datorprogram. Genom att föra statisik över slumpvandringen kan man beräkna olika transportegenskaper i modellen. Det här är en så kallad Monte Carlo-metod, eftersom själva beräkningen är en slumpmässig process. I stället för att följa rörelsebanan för enskilda elektroner, kan man beräkna sannolikheten vid jämvikt för att hitta en elektron i olika tillstånd. Man ställer upp ett system av ekvationer, som relaterar sannolikheterna för att hitta elektronen i olika tillstånd i systemet med flödet, strömmen, mellan de olika tillstånden. Genom att lösa ekvationssystemet fås sannolikhetsfördelningen för elektronerna. Från sannolikhetsfördelningen kan sedan strömmen och materialets transportegenskaper beräknas. En aspekt av hopptransportmodellen som vi studerat är elektronernas diffusion, d.v.s. deras slumpmässiga rörelse. Om man betraktar en samling elektroner, så sprider den med tiden ut sig över ett större område. Det är känt att diffusionshastigheten beror av elfältet, så att elektronerna sprider sig fortare om de påverkas av ett elektriskt fält. Vi har undersökt den här processen, och visat att beteendet är väldigt olika i endimensionella system, jämfört med två- och tredimensionella. I två och tre dimensioner beror diffusionskoefficienten kvadratiskt av elfältet, medan beroendet i en dimension är linjärt. En annan aspekt vi studerat är negativ differentiell konduktivitet, d.v.s. att strömmen i ett material minskar då man ökar spänningen över det. Eftersom det här fenomenet har uppmätts i organiska minnesceller, ville vi undersöka om fenomenet också kan uppstå i hopptransportmodellen. Det visade sig att det i modellen finns två olika mekanismer som kan ge upphov till negativ differentiell konduktivitet. Dels kan elektronerna fastna i fällor, återvändsgränder i systemet, som är sådana att det är svårare att ta sig ur dem då elfältet är stort. Då kan elektronernas medelhastighet och därmed strömmen i materialet minska med ökande elfält. Elektrisk växelverkan mellan elektronerna kan också leda till samma beteende, genom en så kallad coulombblockad. En coulombblockad kan uppstå om antalet ledningselektroner i materialet ökar med ökande spänning. Elektronerna repellerar varandra och ett större antal elektroner kan leda till att transporten blir långsammare, d.v.s. att strömmen minskar.
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The goal of this study is to create a new inventory valuation process for The Switch Drive Systems and to improve its inventory management practices. In the matter of inventories the main problems in the case company are that it doesn’t have consistent valuation methods throughout the company and that information received in ERP system isn’t trustful. The research is qualitative case study. The empirical data is gathered through observing and unstructured interviews. The research shows that material flow process and the inventory valuation must be divided and handled separately but they should interact with each other. The result is a new inventory valuation process which takes many factors of material process under the consideration in order to receive reliable value for inventories.
Resumo:
Degenerative myxomatous mitral valve (DMMV) is a heart disease of high incidence in small animal clinical medicine, affecting mainly older dogs and small breeds. Thus, a scientific investigation was performed in order to evaluate the clinical use of the medicines furosemide and enalapril maleate in dogs with this disease in CHF functional class Ib before and after the treatment was established. For this purpose 16 dogs with the given valve disease were used, separated into two groups: the first received furosemide (n=8) and the second received enalapril maleate (n=8) throughout 56 days. The dogs were evaluated in four stages (T0, T14, T28 and T56 day) in relation to clinical signs, hematological, biochemical and serum assessment, which included serum angiotensin converting enzyme (ACE) and aldosterone, as well as radiography, electrocardiography, Doppler-echocardiography and blood pressure. The results regarding the clinical, hematological and serum chemistry evaluations revealed no significant changes in both groups, but significant reductions in the values of ACE and aldosterone in the group receiving enalapril maleate were verified. The radiographic examination revealed reductions of VHS values and variable Pms wave of the electrocardiogram in both groups, but no changes in blood pressure values were identified. The echocardiogram showed a significant decrease of the variables LVDd/s in the studied groups and the FS% in animals that received only enalapril. Therefore, analysis of results showed that monotherapy based on enalapril maleate showed better efficiency of symptoms control in patients with CHF functional class Ib.
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The usage of digital content, such as video clips and images, has increased dramatically during the last decade. Local image features have been applied increasingly in various image and video retrieval applications. This thesis evaluates local features and applies them to image and video processing tasks. The results of the study show that 1) the performance of different local feature detector and descriptor methods vary significantly in object class matching, 2) local features can be applied in image alignment with superior results against the state-of-the-art, 3) the local feature based shot boundary detection method produces promising results, and 4) the local feature based hierarchical video summarization method shows promising new new research direction. In conclusion, this thesis presents the local features as a powerful tool in many applications and the imminent future work should concentrate on improving the quality of the local features.