• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8
  • 4
  • 1
  • 1
  • Tagged with
  • 18
  • 7
  • 6
  • 6
  • 6
  • 6
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caractérisation du gène Spatial et identification de sa fonction dans les cellules hautement polarisées

Yammine, Miriam 12 December 2011 (has links)
Le gène Spatial est exprimé par des cellules hautement polarisées : les cellules épithéliales du thymus, neuronales du système nerveux central et germinales du testicule. La différenciation de ces cellules est accompagnée d'une polarisation de la distribution de Spatial, dans des structures microtubulaires hautement organisées telles que la manchette, le flagelle et la dendrite.Mon projet a porté sur l’identification de la fonction du gène Spatial au niveau du thymus et du cerveau murins. De plus, j’ai été impliquée dans la caractérisation du gène Spatial chez l’homme et l’évaluation de son impact sur la spermatogenèse et l’infertilité humaine.Nos résultats montrent qu’au niveau du thymus, Spatial est détecté tout au long de l’organogenèse thymique jusqu’aux stades adultes. Son profil d’expression correspond à un « promiscuous gene » impliqué dans l’acquisition de la tolérance des lymphocytes T. Au niveau du système nerveux central, Spatial présente une distribution somatodendritique dans les cultures de neurones hippocampiques et son expression est fortement détectée lors de la poussée dendritique. Nous avons montré que le transport de Spatial du corps cellulaire vers les dendrites est dépendant de la kinésine Kif17. De plus, Spatial semble être impliqué dans la formation des dendrites via la voie de signalisation stimulée par le Nerve Growth Factor.Chez l’homme, le gène H-Spatial est fortement exprimé au niveau du testicule et son expression est spécifique de la spermiogenèse, étape de différenciation des spermatides rondes en spermatozoïdes. Chez les patients infertiles asthéno- et/ou tératozoospermiques, présentant des anomalies de mobilité et de forme des spermatozoïdes, le niveau d’ARNm d’H-Spatial est fortement réduit. Ces résultats suggèrent qu’H-Spatial est un marqueur potentiel de l’infertilité masculine.J’ai également participé à la validation des dendrimères PAMAM (poly-amidoamine) comme vecteurs efficaces pour le transfert de siRNA et d’ADN in vitro sur différents lignées cellulaires et in vivo sur des thymus murins. Ce système pourrait être un moyen thérapeutique pour traiter des immunodéficiences liées aux lymphocytes T. / Spatial gene is expressed in highly polarized cells such as, thymic epithelial cells, testicular germ cells and neuronal cells of the central nervous system. The differentiation of these cells is accompanied by the polarized distribution of Spatial in highly organized microtubule structures such as the manchette, the flagellum and dendrites. This project aims to identify the function of Spatial gene in the thymus and in the brain. Moreover, we characterize Spatial gene in humans and evaluate its impact on spermatogenesis and human infertility.Our results showed that, in the thymus, Spatial is detected throughout the thymic development, until adulthood. Its expression profile corresponds to a ‘promiscuous gene’, implicated in the acquisition of T lymphocyte tolerance.At the level of the central nervous system, Spatial showed a somatodendritic distribution in hippocampal neuron cultures. Moreover, its expression was highly detected during dendritic growth. We have also shown that the transport of Spatial from the cell body to the dendrites is dependent on the kinesin Kif17. In addition, our results suggest that Spatial seems to be implemented in dendrite formation by the Nerve Growth Factor mediated signaling pathway.In the humans, H-Spatial is highly expressed in the testis and its expression is specific to spermiogenesis: the phase of differentiation of round spermatids to spermatozoids. In infertile astheno and/or teratozoospermic patients with sperm shape and mobility anomalies, H-Spatial levels were drastically reduced. These results propose H-Spatial as a potential marker for human male infertility.Finally, we have equally participated in the validation of PAMAM (poly-amidoamine) dendrimers as efficient vectors for the transfer of DNA and siRNA in vitro, in different cell lines; and in vivo, in murine thymi. This system could serve as a new therapeutic model for treating diseases linked to T lymphocytes.
2

Growth, nodulation and yield response of promiscuous and non-promiscuous soybean cultivars to inoculation in different soil types under classhouse and field conditions

Maphosa, T. M., Maphosa, Tsakani Maria 03 1900 (has links)
Thesis (M.Sc. (Agronomy)) --University of Limpopo, 2015 / Soybean (Glycine max (L.) Merrill) is considered to be an important grain legume and an oil crop. It is also important in livestock feeding and improvement of soil fertility through biological nitrogen fixation (BNF). Until recently, soybean was not widely grown by smallholder (SH) farmers in Africa. This has led to breeding of promiscuous varieties to ensure wide adoption of the crop by SH farmers, without the use of inoculants or expensive nitrogen fertilizers. Field and glasshouse experiments were conducted during 2012/2013 growing season. One commercial (specific) variety Dundee and three naturally-nodulating (promiscuous) soybean varieties (TGx-1937-1F, TGx-1740-2F, TGx-1835-10E) were evaluated in a field trial for their growth, nodulation and yield response to B. japonicum strain WB74 inoculation. Seed inoculation in the field enhanced chlorophyll content, number of nodules, nodule dry weight, and the percentage of active nodules, number of pods, hundred seed weight, shelling percentage and grain yield. Varietal differences exerted significant (P≤0.05) effect on all field parameters evaluated except on nodule number and percentage of active nodules. TGx-1937-1F achieved the highest number of nodules (28 per plant) while the highest percentage of active nodules (69%) was achieved by TGx-1740-2F. Huge effect of inoculation was observed on Dundee variety, and resulted in significant grain yield increases (237.8%) while smaller gain increases were observed in TGx-1740-2F (43.9%) and TGx-1835-10E (38.7%). The yield of TGx-1937-1F did not respond to inoculation. Two promiscuous (TGx-1937-1F and TGx-1740-2F) varieties and one commercial (Dundee) variety were evaluated in a glasshouse trial for their growth and nodulation response to inoculation in different soil types (sandy clay loam, sandy loam, loamy sand) of Limpopo Province. In the glasshouse inoculation showed effect on chlorophyll content only, and effect of soybean variety was found to be significant on days to flowering, chlorophyll content, plant height, number of nodules and root dry weight. Soil type showed significant effect on all parameters evaluated in the glasshouse study except on nodule dry weight. Loamy sand soil from Ga-Molepo gave tallest plants and highest nodule number at 61 cm and 29 nodules/plant compared to other soils. All soils evaluated in the study resulted in percent active nodules ranging from 74.5% to 77.4% showing possibility of presence of cowpea-type rhizobia in Limpopo soils capable of fixing atmospheric nitrogen. Inoculation x variety interaction was significant on days to flowering, plant height and chlorophyll content. Inoculant application in TGx-1740-2F variety reduced the number of days it took to flowering from 61 to 54 days and increased its plant height by 57% from 44.8 to 67.9 cm. Eighty three percent (83%) increase on chlorophyll content of variety Dundee was observed due to effect of inoculation. Inoculation x soil type interaction had significant effect on plant height and dried plant biomass. Varity x soil type interaction influenced chlorophyll content, while the interactive effects of inoculation x variety x soil type were significant on chlorophyll content only. The study showed that it is beneficial to inoculate the soybean varieties studied, especially the commercial variety Dundee, in order to enhance their growth, nodulation and yield. / Department of Agriculture Forestry and Fisheries
3

Reproductive Characteristics, Multiple Paternity and Mating System in a Central Florida Population of the Gopher Tortoise, <em>Gopherus polyphemus</em>

Colson-Moon, Jamie Colleen 10 July 2003 (has links)
I studied the reproductive characteristics and mating systems of a central Florida population of gopher tortoises (Gopherus polyphemus). Using x-radiography, females were monitored for stage in egg-shelling and clutch size. Eggs began to appear on x-ray photographs in the first week of May in both 2001 and 2002; however, fully shelled eggs were not found before the end of May. In total 55% of the females x-rayed were gravid. Clutch sizes ranged from 4-12 with a mean of 7.29, with a mean clutch mass of 40.9 g. Clutch size increased with an increase in mean carapace length and mean plastron length. Mean clutch mass also increased with mean carapace length of females. Hatchlings began to emerge in late August, with incubation times ranging from 83 to 96 days. 50% of the eggs hatched, with 16.2% of the eggs showing no signs of development when opened. Hatchling mass averaged 30.7 g and was positively correlated with egg mass. DNA was extracted from blood samples obtained from females and their offspring, and from the sexually mature males in the population. Nine microsatellite loci were amplified and genotypes constructed for each individual. There is evidence for promiscuous mating in gopher tortoises. Multiple paternity was detected in two of the seven clutches (28.6 %). In the clutches with multiple fathers, fertilization was highly skewed to one male, with primary male fertilizing over 70% of the clutch. Females with multiple-sired clutches were significantly smaller than females with single-sired clutches. Among the clutches assayed only one male fertilized more than one clutch, indicating that insemination of females is evenly spread among males of similar sizes. However, males assigned as fathers were significantly larger than other sampled males which may mean that larger males have an advantage in fertilization of clutches. Conservation efforts should consider the impact of the mating system on reproduction in a population, and the possible impact of the relocation of larger males on recipient populations.
4

Immunological responses to fungal epitope peptides

Sheth-Ughade, Parita January 2012 (has links)
Introduction: Fungi are common aeroallergens responsible for at least 3% – 10% of allergic diseases worldwide, with the proportion hugely variable in different populations. Treatment is complicated by viable nature and disease causing ability of the allergen and is often only palliative. Thus, this study aimed to serve as a pilot investigation to design novel anti-allergy therapeutics to cure allergy at the molecular level. It investigates the effect of wild type fungal peptides and corresponding variant peptides on allergy associated immunological responses – cellular and cytokine based – to use such variant peptides to cause the delicate shift from an allergic to a normal immune response. Further, the study explores the role of bioinformatics in investigating allergy and designing novel therapeutics. Methods: This study used ProPred, a bioinformatics software, to predict wild type peptides from selected allergens of Aspergillus fumigatus and Alternata alternaria for a target population. These were then modified to generate single amino acid variants. Both these peptide sets were tested to compare the cellular and cytokine patterns they generated in sensitised (n = 3) and healthy volunteers (n = 3) to check for anti-allergy responses that may be exerted by certain variants. The recruited population was also subjected to skin prick testing (SPT, n = 46) to check for co-sensitisations patterns and HLA typing (n = 40) to evaluate ProPred accuracy for peptide prediction. This study also attempted an in silico search for unknown Penicillium chrysogenum allergens by comparing known Penicillium and A. fumigatus allergens to identify probable agents of co-sensitization. Results: Of the wild type and variant peptides tested in this study, one variant peptide – peptide 1.1v from Asp f 2 – was successfully identified to change the cellular and cytokine profile to promote an anti-allergic response when compared to its corresponding wild type form (1.1o). This candidate is a good target for further investigation for use in peptide immunotherapy. Further, 8 shared allergens between A. fumigatus and P. chrysogenum were identified that may possibly be agents of co-sensitization between these species. SPT results indicated maximum subject co-sensitization between A. fumigatus and Candida albicans and P. chrysogenum. HLA typing results demonstrated the efficiency of ProPred to be 96.29%, thus implying that bioinformatics can effectively be used to study allergy in this novel manner. Conclusion: This study has demonstrated that variant peptides with a single amino acid change can cause the delicate shift from an allergic to a healthy immune response in sensitised subjects. This approach – in combination with other allergy associated factors such as epitope specificity for HLA types and inherent co-sensitization patterns in a population – can effectively be used to design peptide candidates for immunotherapy to target allergy at the molecular level. With promising results obtained in this pilot study, this approach guarantees further investigation in immunotherapy. This study has also demonstrated that bioinformatics can be effectively used to design and execute allergy studies in a targeted and inexpensive manner.
5

Análise do transcriptoma durante a ontogenia do timo. / Analysis of the transcriptoma during the antogenia of the thymus.

Magalhães, Danielle Aparecida Rosa de 10 May 2007 (has links)
O timo é um órgão complexo estruturado por um estroma, o qual é formado principalmente por células epiteliais corticais (cTECs) e por células epiteliais medulares (mTECs) além de outros tipos celulares como células dendríticas (DC), macrófagos, linfócitos B e fibroblastos. Além disso, os precursores das células T originados da medula óssea chegam ao timo (timócitos) se maturando em linfócitos T, os quais migram para a periferia. O timo é, portanto, o local de eventos muito importantes durante a maturação do sistema imune, incluindo o controle de sua própria homeostase. No presente estudo, procuramos retratar as principais características do timo por meio da análise da expressão gênica em grande escala, isto é, descrevendo parte de seu transcriptoma. Fizemos uso da tecnologia dos cDNA microarrays em duas versões. Na primeira delas utilizamos cDNA microarrays construídos em lâminas de vidro e sondas fluorescentes marcadas com fluorocromos Cy3 ou Cy5 e, na segunda versão utilizamos cDNA microarrays em membranas de náilon e sondas radioativas marcadas com o isótopo 33P. Para a análise dos dados, utilizamos programas de bioinformática dedicados, tais como o SAM (Significance analysis of microarrays) e o Cluster e TreeView. Três conjuntos de resultados foram possíveis. No primeiro conjunto observamos a ocorrência da expressão gênica promíscua (PGE) de antígenos de tecidos/órgãos parenquimatosos (TSAs), demarcando sua emergência temporal durante a ontogenia do timo murino, a qual é influenciada pelo background genético das linhagens isogênicas estudadas. A ocorrência da PGE no timo é associada às bases genético-moleculares da indução de tolerância imunológica nas células T, contribuindo com a prevenção da auto-imunidade. O segundo conjunto de resultados consistiu na análise da expressão gênica do timo de camundongos nocautes (KO) envolvendo genes importantes para a maturação das células T, tais como TCR?, LAT, Rel-b, RAG-1 e CD3?, possibilitando a observação de seus efeitos na regulação da transcrição neste órgão. Finalmente, o terceiro conjunto consistiu na definição da dissecação molecular virtual do timo. Por meio de perfis de expressão gênica particulares exibidos por cada tipo principal que povoa o timo, foi possível dissecar este órgão usando a tecnologia dos cDNA microarrays. / The thymus is a complex organ structured by a stroma, which is formed mainly by cortical epithelial cells (cTECs) and medullary epithelial cells (mTECs) besides of other cell types such as dendritic cells (DC), macrophages, B lymphocytes and fibroblasts. Moreover, the T cell precursors arising from the bone marrow reach the thymus (thymocytes) maturing in T lymphocytes, which migrate to the periphery. Thus, the thymus is the place of very important events during the maturation of the immune system, including the control of their own homeostasis. In the present study, we search to picture the main characteristics of the thymus by means of the large scale gene expression analysis that is, describing part of their transcriptome. We made use of the cDNA microarray technology in two versions. In the first one we used cDNA microarrays constructed on glass slides and fluorescent probes labeled with the fluorochromes Cy3 or Cy5 and in the second version we used cDNA microarrays on nylon membranes and radioactive probes labeled with 33P isotope. To data analysis we used dedicated bioinformatics programs, such as SAM (significance analysis of microarrays) and Cluster-Tree View. Three sets of results were possible. In the first set we observed the occurrence of the promiscuous gene expression (PGE) of parenchymal tissue/organ specific antigens (TSAs), demarking their temporal emergence during the murine thymus ontogeny, which is influenced by the genetic background of the inbred strains studied. The occurrence of PGE in the thymus is associated to the molecular-genetics basis of the immune tolerance of T cells, contributing with the prevention of autoimmunity. The second set of results consisted in the analysis of gene expression of thymus from knockout mice (KO) involving genes important for T cell maturation, such as TCR?, LAT, Relb, RAG-1 and CD3?, allowing the observation of its effects on the transcription regulation in this organ. Finally, the third set consisted in the definition of the virtual molecular dissection of the thymus. By means of particular gene expression profiling featured by each main cell type populating the thymus, it was possible to dissect this organ using the cDNA microarray technology.
6

Reproductive characteristics, multiple paternity and mating system in a central florida population of the gopher tortoise, Gopherus polyphemus [electronic resource] / by Jamie Colleen Colson-Moon.

Colson-Moon, Jamie Colleen. January 2003 (has links)
Title from PDF of title page. / Document formatted into pages; contains 69 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: I studied the reproductive characteristics and mating systems of a central Florida population of gopher tortoises (Gopherus polyphemus). Using x-radiography, females were monitored for stage in egg-shelling and clutch size. Eggs began to appear on x-ray photographs in the first week of May in both 2001 and 2002; however, fully shelled eggs were not found before the end of May. In total 55% of the females x-rayed were gravid. Clutch sizes ranged from 4-12 with a mean of 7.29, with a mean clutch mass of 40.9 g. Clutch size increased with an increase in mean carapace length and mean plastron length. Mean clutch mass also increased with mean carapace length of females. Hatchlings began to emerge in late August, with incubation times ranging from 83 to 96 days. 50% of the eggs hatched, with 16.2% of the eggs showing no signs of development when opened. Hatchling mass averaged 30.7 g and was positively correlated with egg mass. / ABSTRACT: DNA was extracted from blood samples obtained from females and their offspring, and from the sexually mature males in the population. Nine microsatellite loci were amplified and genotypes constructed for each individual. There is evidence for promiscuous mating in gopher tortoises. Multiple paternity was detected in two of the seven clutches (28.6 %). In the clutches with multiple fathers, fertilization was highly skewed to one male, with primary male fertilizing over 70% of the clutch. Females with multiple-sired clutches were significantly smaller than females with single-sired clutches. Among the clutches assayed only one male fertilized more than one clutch, indicating that insemination of females is evenly spread among males of similar sizes. However, males assigned as fathers were significantly larger than other sampled males which may mean that larger males have an advantage in fertilization of clutches. / ABSTRACT: Conservation efforts should consider the impact of the mating system on reproduction in a population, and the possible impact of the relocation of larger males on recipient populations. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.
7

The In Silico Search for an Endogenous Anti-Alzheimer's Therapeutic

Meek, Autumn 09 December 2011 (has links)
Alzheimer’s disease (AD) is a progressive, degenerative neurological disorder for which there is no cure. The causative agent is ?-amyloid (A?) which becomes neurotoxic upon conformational change from ?-helix to ?-sheet. In silico methods have been used to indentify endogenous small molecules of the brain that are capable of binding to A? to inhibit conformational changes; this is a novel approach to the disease. Through the use of computational methods, several small molecules that are endogenous to the brain, such as phosphoserine, have been identified as being capable of binding to the monomeric forms of A?; in vitro studies support their role as anti-aggregants. One of the small molecules identified through these in silico methods, 3-hydroxyanthranilic acid (3HAA) has been developed through the use of Quantitative Structure-Activity Relationship (QSAR) studies to design more potent analogues. These in silico studies have also examined the capacity of synthetic compounds (structurally similar to endogenous molecules) to bind to both A? and other proteins affiliated with AD. Results indicate the potential for a single molecule to bind “promiscuously” to multiple proteins bearing a common BBXB (where B is a basic amino acid) motif affiliated with AD. This will allow for the development of molecules to target AD in a multifaceted approach. Furthermore, these small molecules can be selected through the use of “physinformatics” to bind with equal efficacy to the HHQK and LVFF regions (which play a role in the misfolding process) of A?; this will prevent conformational changes of the protein. A novel diagnostic imaging agent for AD has also been developed through computational methods; solapsone (formerly used to treat leprosy) has been identified as being structurally similar to species that bind to A? to initiate conformational changes. Results show that solapsone can chelate gadolinium, used in MRI, and bind to the soluble forms of A?, allowing for imaging of the toxic species in the human brain, and thus a definitive diagnosis of AD (which is not currently possible with living patients). Computational methods have proved useful in developing a new approach to treating AD, and designing a novel imaging agent.
8

Análise do transcriptoma durante a ontogenia do timo. / Analysis of the transcriptoma during the antogenia of the thymus.

Danielle Aparecida Rosa de Magalhães 10 May 2007 (has links)
O timo é um órgão complexo estruturado por um estroma, o qual é formado principalmente por células epiteliais corticais (cTECs) e por células epiteliais medulares (mTECs) além de outros tipos celulares como células dendríticas (DC), macrófagos, linfócitos B e fibroblastos. Além disso, os precursores das células T originados da medula óssea chegam ao timo (timócitos) se maturando em linfócitos T, os quais migram para a periferia. O timo é, portanto, o local de eventos muito importantes durante a maturação do sistema imune, incluindo o controle de sua própria homeostase. No presente estudo, procuramos retratar as principais características do timo por meio da análise da expressão gênica em grande escala, isto é, descrevendo parte de seu transcriptoma. Fizemos uso da tecnologia dos cDNA microarrays em duas versões. Na primeira delas utilizamos cDNA microarrays construídos em lâminas de vidro e sondas fluorescentes marcadas com fluorocromos Cy3 ou Cy5 e, na segunda versão utilizamos cDNA microarrays em membranas de náilon e sondas radioativas marcadas com o isótopo 33P. Para a análise dos dados, utilizamos programas de bioinformática dedicados, tais como o SAM (Significance analysis of microarrays) e o Cluster e TreeView. Três conjuntos de resultados foram possíveis. No primeiro conjunto observamos a ocorrência da expressão gênica promíscua (PGE) de antígenos de tecidos/órgãos parenquimatosos (TSAs), demarcando sua emergência temporal durante a ontogenia do timo murino, a qual é influenciada pelo background genético das linhagens isogênicas estudadas. A ocorrência da PGE no timo é associada às bases genético-moleculares da indução de tolerância imunológica nas células T, contribuindo com a prevenção da auto-imunidade. O segundo conjunto de resultados consistiu na análise da expressão gênica do timo de camundongos nocautes (KO) envolvendo genes importantes para a maturação das células T, tais como TCR?, LAT, Rel-b, RAG-1 e CD3?, possibilitando a observação de seus efeitos na regulação da transcrição neste órgão. Finalmente, o terceiro conjunto consistiu na definição da dissecação molecular virtual do timo. Por meio de perfis de expressão gênica particulares exibidos por cada tipo principal que povoa o timo, foi possível dissecar este órgão usando a tecnologia dos cDNA microarrays. / The thymus is a complex organ structured by a stroma, which is formed mainly by cortical epithelial cells (cTECs) and medullary epithelial cells (mTECs) besides of other cell types such as dendritic cells (DC), macrophages, B lymphocytes and fibroblasts. Moreover, the T cell precursors arising from the bone marrow reach the thymus (thymocytes) maturing in T lymphocytes, which migrate to the periphery. Thus, the thymus is the place of very important events during the maturation of the immune system, including the control of their own homeostasis. In the present study, we search to picture the main characteristics of the thymus by means of the large scale gene expression analysis that is, describing part of their transcriptome. We made use of the cDNA microarray technology in two versions. In the first one we used cDNA microarrays constructed on glass slides and fluorescent probes labeled with the fluorochromes Cy3 or Cy5 and in the second version we used cDNA microarrays on nylon membranes and radioactive probes labeled with 33P isotope. To data analysis we used dedicated bioinformatics programs, such as SAM (significance analysis of microarrays) and Cluster-Tree View. Three sets of results were possible. In the first set we observed the occurrence of the promiscuous gene expression (PGE) of parenchymal tissue/organ specific antigens (TSAs), demarking their temporal emergence during the murine thymus ontogeny, which is influenced by the genetic background of the inbred strains studied. The occurrence of PGE in the thymus is associated to the molecular-genetics basis of the immune tolerance of T cells, contributing with the prevention of autoimmunity. The second set of results consisted in the analysis of gene expression of thymus from knockout mice (KO) involving genes important for T cell maturation, such as TCR?, LAT, Relb, RAG-1 and CD3?, allowing the observation of its effects on the transcription regulation in this organ. Finally, the third set consisted in the definition of the virtual molecular dissection of the thymus. By means of particular gene expression profiling featured by each main cell type populating the thymus, it was possible to dissect this organ using the cDNA microarray technology.
9

Hop-by-Hop Transport Control for Multi-Hop Wireless Networks

Scofield, Daniel N. 17 April 2007 (has links) (PDF)
TCP can perform poorly in multi-hop wireless networks due to problems with contention and poor feedback from end-to-end control algorithms. This thesis explores the design of a hop-by-hop transport protocol (HxH). By allowing intermediate nodes to actively participate, the protocol can respond more quickly to changing network conditions and exploit the unique characteristics of wireless networks. Results indicate that hop-by-hop transport can achieve throughput rates that are double those of TCP, depending on the speed of the wireless links.
10

Análise da expressão gênica promíscua no timo de camundongos NOD (non obese diabetic) durante a emergência do Diabetes melitus tipo 1 / Analysis of the promiscuous gene expression in the thymus of NOD (non obese diabetic) mice during onset of type 1 diabetes mellitus

Fornari, Thaís Arouca 17 March 2008 (has links)
A tolerância imunológica é a propriedade essencial do sistema imune que controla as reações patológicas contra antígenos do próprio. O timo é visto como o principal órgão envolvido com a indução de tolerância aos antígenos próprios que são expressos pelas células tímicas (tolerância central), enquanto que a indução de tolerância aos antígenos relacionados a outros tecidos (TRAs) tem sido atribuída aos mecanismos de tolerância extratímica (tolerância periférica). Entretanto, a evidência da expressão de TRAs de órgãos e tecidos parenquimais no timo pelas células medulares epiteliais (mTECs) de camundongos e de humanos a qual foi referida como expressão gênica promíscua (PGE) reforçou a concepção de tolerância central de TRAs. O controle molecular dessa expressão tem sido atribuído ao gene Aire (Auto immune regulator) que é um regulador de transcrição. No presente estudo, procurou-se retratar a expressão gênica promíscua no timo de camundongos NOD (Non Obese Diabetic) por meio da análise da expressão gênica em grande escala, ou seja, descrevendo seu transcriptoma usando a tecnologia de cDNA microarrays. Para a análise dos dados utilizamos programas de bioinformática dedicados a microarrays bem como dados de bancos para a caracterização da PGE e susceptibilidade genética ao diabetes melitus do tipo 1 (DM-1). Três conjuntos de resultados puderam ser evidenciados. No primeiro conjunto observou-se a ocorrência da PGE de antígenos tecidos/órgãos parenquimatosos (TRAs) em timos recém removidos e em in vitro em cultura ATOC de camundogos NOD pré-autoimunes e autoimunes (diabéticos). O segundo conjunto de resultados consistiu na análise do efeito da inativação do transcrito de gene Aire na expressão gênica do timo de camundongos NOD in vitro em cultura ATOC. Finalmente, no último conjunto de dados, demonstrou-se que certos genes de TRAs com expressão promíscua, se encontram em regiões cromossômicas de susceptibilidade ao DM - 1 (idds). Como três deles (Il-4, Cd4 e Cdk4) são diretamente relacionados com a patogenia do DM-1 em camundongos foi possível estabelecer um paralelo entre PGE e susceptibilidade genética. / Immunologic tolerance is an essential property of the immune system, which controls immune reactions directed against the body self components. The thymus is seen as the main organ involved with the tolerance induction to self antigens, which are expressed by the thymic cells (central tolerance), while the tolerance induction to the diverse other peripheral tissues and organs is attributed to extra thymic mechanisms (peripheral tolerance). Nevertheless, the evidence for the expression of peripheral tissue related antigens (TRAs) in the thymus by the medullary thymic epithelial cells (mTECs) of mice and humans, which have been termed to as promiscuous gene expression (PGE), has contributed to the concept of central tolerance to TRAs. The molecular control of such gene expression has been attributed to the Aire (autoimmune regulator) gene, which plays a role as a transcriptional regulator. In the present study, we searched to picture PGE in the thymus of NOD (non obese diabetic) mice by means of high throughput gene expression, analyzing the transcriptome by the cDNA microarray method. To analyzing data we used bioinformatics programs dedicated to microarrays and specialized data banks to characterize PGE and genetic susceptibility to type 1 diabetes mellitus (DM-1). Studying pre and autoimmune NOD mice, we evidentiate three sets of results. In the first set, it was observed the occurrence of PGE of parenchymal tissue/organs antigens (TRAs) in fresh thymuses and in thymuses cultured in vitro in adult thymus organ cultures (ATOC). The second set of results consisted in the analysis of the effect of in vitro (ATOC) Aire gene silencing on PGE. Finally, in the third data set, we demonstrated that certain promiscuously expressed genes are positioned in DM-1 genetic susceptibility chromosomal regions (idds). As three of such genes (IL4, Cd4 and Cdk4) are directly associated to the DM-1 pathogenesis in mice, it was possible to establishing a parallel between PGE in the thymus and genetic susceptibility to this autoimmune disease.

Page generated in 0.0907 seconds