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  • 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.
31

Oncogenic Signaling Pathways Activated by Lysophosphatidic Acid (LPA) in Ovarian Carcinoma

Goldsmith, Zachariah G. January 2009 (has links)
Ovarian cancer is currently the most fatal gynecologic cancer and the fifth leading cause of fatal cancer in women overall. As compared to the better-characterized malignancies, such as such as prostate, breast and colorectal cancers, there have been no major changes in methods of detection or treatment of ovarian cancers since the 1970's. As a result, the incidence and age-adjusted death rates for this disease have improved only marginally since that time. The molecular changes required for ovarian cancer pathogenesis remain poorly defined. Lysophosphatidic acid (LPA) has emerged as a biomarker present in the ascitic fluid and serum of ovarian cancer patients. Subsequent studies have identified LPA as an agonist for G protein coupled receptors (GPCRs). LPA has been well characterized as a pro-migratory factor in ovarian cancer and other cell systems. However, the role of LPA in mediating a proliferative response in ovarian cancer cells has yet to be fully characterized. In addition, the identity of the G protein pathways involved in this proliferative response remains a major unresolved question in the field. To investigate the mitogenic role of LPA in ovarian cancers, a panel of representative human ovarian cancer cells was assembled. A series of immunoblot and RT-PCR analyses was used to profile the LPA receptors and Gα-subunits expressed in these cells. In addition to verifying the migratory effect of LPA in these cells, a series of proliferation assays were used to investigate the potential role for LPA as a mitogen. The results indicate that stimulation with LPA results in a robust and statistically significant proliferative response. This response was quantified using multiple approaches. In addition, the proliferative response was observed in three independent ovarian cancer cell lines using concentrations of LPA within the range found in vivo in the ascitic fluid of ovarian cancer patients. Taken together, these data for the first time validate the role of LPA as a mitogen in ovarian cancer cells. To gain further insight into the oncogenic signaling response stimulated by LPA, activation of the mitogen activated protein kinase (MAPK) modules was determined. Using a series of immunoblot analyses and kinase assays, LPA was found to stimulate ERK as well as JNK modules. To investigate the functional roles of these pathways, a series of proliferation assays were carried out using inhibitors of ERK and JNK signaling. Consistent with the role of ERK as a crucial regulator of growth-factor induced proliferation in other cell systems, the results demonstrated a significantly attenuated growth response to LPA with ERK inhibition. Moreover, additional studies demonstrated for the first time that inhibition of JNK signaling significantly attenuates the proliferative response to LPA. In order to investigate the potential role of Gα12 in mediating the oncogenic response to LPA, the activation status of Gα12 was monitored in ovarian cancer cells stimulated with LPA. These studies demonstrate rapid activation of Gα12 with LPA stimulation. Finally to investigate the functional role of LPA-Gα12 signaling, a series of cell lines was established which express a dominant negative form of Gα12. Expression of this construct induced complete inhibition of Gα12 activation by LPA. These cells were then used to determine the effects of Gα12 inhibition on the oncogenic response to LPA. Consistent with the role of G12 family members in mediating cell migration, these cells demonstrated an attenuated migratory response to LPA. In addition, inhibition of Gα12 resulted in an attenuated proliferative response to serum. Finally, to investigate the role of Gα12 in mediating the proliferative response to LPA, a series of proliferation assays was carried out. The results indicated a significant > 50% inhibition in multiple ovarian cancer cell lines. Taken together, these results, presented here for the first time, establish that LPA is a potent mitogen that induces a proliferative response in human ovarian carcinoma cells. Although LPA had previously been shown to induce a proliferative response in multiple other cell types, it had not been known if LPA activates specific oncogenic pathways. This thesis tested the hypothesis that LPA, which is crucially involved in the pathophysiology of ovarian carcinoma, induces the activation of Gα12. In this context, the data presented here demonstrating a novel role for Gα12- which has been defined as the gep oncogene - in mediating this proliferative response in ovarian carcinoma, represents a major finding in the field. / Molecular Biology and Genetics
32

Lysophosphatidic Acid Promotes Cell Migration through STIM1- and Orai1-Mediated Ca2+i Mobilization and NFAT2 Activation

Jans, R., Mottram, L., Johnson, D.L., Brown, A.M., Sikkink, Stephen, Ross, K., Reynolds, N.J. January 2013 (has links)
No / Lysophosphatidic acid (LPA) enhances cell migration and promotes wound healing in vivo, but the intracellular signaling pathways regulating these processes remain incompletely understood. Here we investigated the involvement of agonist-induced Ca2+ entry and STIM1 and Orai1 proteins in regulating nuclear factor of activated T cell (NFAT) signaling and LPA-induced keratinocyte cell motility. As monitored by Fluo-4 imaging, stimulation with 10 μM LPA in 60 μM Ca2+o evoked Ca2+i transients owing to store release, whereas addition of LPA in physiological 1.2 mM Ca2+o triggered store release coupled to extracellular Ca2+ entry. Store-operated Ca2+ entry (SOCE) was blocked by the SOCE inhibitor diethylstilbestrol (DES), STIM1 silencing using RNA interference (RNAi), and expression of dominant/negative Orai1R91W. LPA induced significant NFAT activation as monitored by nuclear translocation of green fluorescent protein-tagged NFAT2 and a luciferase reporter assay, which was impaired by DES, expression of Orai1R91W, and inhibition of calcineurin using cyclosporin A (CsA). By using chemotactic migration assays, LPA-induced cell motility was significantly impaired by STIM1, CsA, and NFAT2 knockdown using RNAi. These data indicate that in conditions relevant to epidermal wound healing, LPA induces SOCE and NFAT activation through Orai1 channels and promotes cell migration through a calcineurin/NFAT2-dependent pathway.
33

Processamento e análise digital de imagens em estudos da cinética de recristalização de ligas Al-Mg-X / Processing and analysis of digital images in studies of recrystallization kinectics of Al-Mg-X alloys

Ignacio, Juliano da Silva 11 November 2013 (has links)
O Processamento e Análise Digital de Imagens é utilizado cada vez mais para agilizar processos, aumentar a precisão, segurança e confiabilidade de dados extraídos de imagens nas mais diversas áreas de pesquisa. No entanto, muitas vezes é necessário que o pesquisador faça, ele próprio, o pré-processamento das imagens, mesmo não sendo um especialista nesta área. Isto coloca em risco o próprio objetivo do uso do Processamento e Análise Digital de Imagens. Este trabalho analisa a relação dos dados extraídos de uma imagem (micrografia) através do software livre ImageJ com relação ao seu processamento final desejado, avaliando assim, a necessidade ou não, de uma ou mais sequencias de pré-processamento para adequar a imagem para o processamento final, indicando ainda quais fatores de influência apresentam informações irrelevantes ou incompletas para o processamento final utilizando ferramentas da Lógica Paraconsistente Anotada. Os resultados obtidos mostram que esta abordagem carece de informações diversificadas sobre a imagem original capturada que possam subsidiar a tomada de decisão quanto aos procedimentos necessários e, para o pré-processamento adequado ao objetivo desejado. / Processing and Analysis of Digital Images is increasingly used to streamline processes, improve accuracy, safety and reliability of data extracted from images in various research areas. However, it is often necessary for the researcher to make himself, the preprocessing of images, although not an expert in this area. This puts at risk the very purpose of using the Processing and Analysis of Digital Images. This paper analyzes the relationship of the data extracted from an image (micrograph) through the free software ImageJ, with respect to its desired final processing. Thus, evaluating the necessity or not, of one or more sequences of preprocessing to adjust the image to the final processing, further indicating which factors influence presents incomplete or irrelevant information for final processing using tools of Annotaded Paraconsistent Logic. The results show that this approach lacks diversified information about the original image captured that can support decision making about procedures for appropriate preprocessing to the desired goal.
34

Processamento e análise digital de imagens em estudos da cinética de recristalização de ligas Al-Mg-X / Processing and analysis of digital images in studies of recrystallization kinectics of Al-Mg-X alloys

Juliano da Silva Ignacio 11 November 2013 (has links)
O Processamento e Análise Digital de Imagens é utilizado cada vez mais para agilizar processos, aumentar a precisão, segurança e confiabilidade de dados extraídos de imagens nas mais diversas áreas de pesquisa. No entanto, muitas vezes é necessário que o pesquisador faça, ele próprio, o pré-processamento das imagens, mesmo não sendo um especialista nesta área. Isto coloca em risco o próprio objetivo do uso do Processamento e Análise Digital de Imagens. Este trabalho analisa a relação dos dados extraídos de uma imagem (micrografia) através do software livre ImageJ com relação ao seu processamento final desejado, avaliando assim, a necessidade ou não, de uma ou mais sequencias de pré-processamento para adequar a imagem para o processamento final, indicando ainda quais fatores de influência apresentam informações irrelevantes ou incompletas para o processamento final utilizando ferramentas da Lógica Paraconsistente Anotada. Os resultados obtidos mostram que esta abordagem carece de informações diversificadas sobre a imagem original capturada que possam subsidiar a tomada de decisão quanto aos procedimentos necessários e, para o pré-processamento adequado ao objetivo desejado. / Processing and Analysis of Digital Images is increasingly used to streamline processes, improve accuracy, safety and reliability of data extracted from images in various research areas. However, it is often necessary for the researcher to make himself, the preprocessing of images, although not an expert in this area. This puts at risk the very purpose of using the Processing and Analysis of Digital Images. This paper analyzes the relationship of the data extracted from an image (micrograph) through the free software ImageJ, with respect to its desired final processing. Thus, evaluating the necessity or not, of one or more sequences of preprocessing to adjust the image to the final processing, further indicating which factors influence presents incomplete or irrelevant information for final processing using tools of Annotaded Paraconsistent Logic. The results show that this approach lacks diversified information about the original image captured that can support decision making about procedures for appropriate preprocessing to the desired goal.
35

Anti-lysophosphatidic acid antibodies improve traumatic brain injury outcomes

Crack, Peter, Zhang, Moses, Morganti-Kossmann, Maria, Morris, Andrew, Wojciak, Jonathan, Fleming, Jonathan, Karve, Ila, Wright, David, Sashindranath, Maithili, Goldshmit, Yona, Conquest, Alison, Daglas, Maria, Johnston, Leigh, Medcalf, Robert, Sabbadini, Roger, Pebay, Alice January 2014 (has links)
BACKGROUND:Lysophosphatidic acid (LPA) is a bioactive phospholipid with a potentially causative role in neurotrauma. Blocking LPA signaling with the LPA-directed monoclonal antibody B3/Lpathomab is neuroprotective in the mouse spinal cord following injury.FINDINGS:Here we investigated the use of this agent in treatment of secondary brain damage consequent to traumatic brain injury (TBI). LPA was elevated in cerebrospinal fluid (CSF) of patients with TBI compared to controls. LPA levels were also elevated in a mouse controlled cortical impact (CCI) model of TBI and B3 significantly reduced lesion volume by both histological and MRI assessments. Diminished tissue damage coincided with lower brain IL-6 levels and improvement in functional outcomes.CONCLUSIONS:This study presents a novel therapeutic approach for the treatment of TBI by blocking extracellular LPA signaling to minimize secondary brain damage and neurological dysfunction.
36

Floristický a fytocenologický průzkum květeny severní části CHKO Blanský les / Floristic and phytosociological survey of the flora northern part CHKO Blansky les

TURJANICOVÁ, Alena January 2015 (has links)
This paper, deals with the status of the flora around the village Dobčice, which is located in the northern part of the Protected Landscape Area Blanský les. The area of interest covers an area of 12.6 hectares and includes two nature reserves: NR Chřášťanský vrch and NR Vysoká Běta. In the teritory are located eleven types of terestrial biotopes, for which was created 35 phytosociological relevés, including their photographs and localization. Further fieldwork that was carried out in the theritory was floristic survey. In the monitored area was found total of 264 species of plants and mosses. Six of these species is classified in the 3rd edition of the Red List of vascular plants of the Czech Republic. For each of the found species was created an entry in the herbarium.
37

Mechanismus vzniku perinukleárních aktinových mikrofilament a jejich funkce v buněčné motilitě / The assembly of perinuclear actin stress fibers and their role in cell movement

Votavová, Barbora January 2018 (has links)
Nucleus is the largest cellular organelle in animal cells. Due to its bulky nature and the stiffness of nuclear lamina the nucleus constitutes the substantial problem for migrating cells where nucleus has to move. The actomyosin generated forces and LINC (Linker of Nucleoskeleton and Cytoskeleton) complex, that is composed of SUN and nesprin proteins, play key role in nuclear movement. LINC complex mechanically couples nuclear lamina to the cytoskeleton and allows the forces exerted by the cytoskeleton to move the nucleus. Perinuclear actin fibers, also termed actin cap, mechanically link focal adhesions with nucleus and they may generate forces that position the nucleus in a way that is optimal for cellular movement. However, molecular mechanism of how perinuclear actin fibers and LINC complex orchestrate the nuclear movement and functional significance of this process remain poorly understood. The specific aim was to determine the mechanisms by which perinuclear actin fibers are formed and how are these mechanisms employed to facilitate cell migration. The role of LPA-RhoA signaling axis and LINC complex in the formation of perinuclear actin fibers was also examined. It was confirmed that LPA is essencial stimulus during actin cap formation. On the other hand, FAK kinase was found necessary for...
38

Optimal beam loading in a nanocoulomb-class laser wakefield accelerator

Couperus, Jurjen Pieter 20 November 2018 (has links)
Laser plasma wakefield accelerators have seen tremendous progress in the last years, now capable of producing electron beams in the GeV energy range. The inherent few-femtoseconds short bunch duration of these accelerators leads to ultra-high peak-currents. Reducing the energy spread found in these accelerators, while scaling their output to hundreds of kiloampere peak current would stimulate the next generation of radiation sources covering high-field THz, high-brightness X-ray and -ray sources, compact free-electron lasers and laboratory-size beam-driven plasma accelerators. At such high currents, an accelerator operates in the beam loaded regime where the accelerating field is strongly modified by the self-fields of the injected bunch, potentially deteriorating key beam parameters. However, if appropriately controlled, the beam loading effect can be employed to improve the accelerator’s performance, specifically to reduce the energy spread. In this thesis the beam-loading effect is systematically studied at a quasi-monoenergetic nanocoulomb-class laser wakefield accelerator. For this purpose, a tailored scheme of the self-truncated ionisation injection process is introduced for the non-linear bubble regime. This scheme facilitates stable and tunable injection of high-charge electron bunches within a short and limited time-frame, ensuring low energy spread right after injection. Employing a three millimetres gas-jet acceleration medium and a moderate 150 TW short pulse laser system as driver, unprecedented charges of up to 0.5 nC within a quasi-monoenergetic peak and energies of ~0.5 GeV are achieved. Studying the beam loading mechanism, it is demonstrated that at the optimal loading condition, i.e. at a specific amount of injected charge, performance of the accelerator is optimised with a minimisation of the energy spread. At a relative energy spread of only 15%, the associated peak current is around 10 kA, while scaling this scheme to operate with a petawatt driver laser promises peak-currents up to 100 kA.
39

Lärande på arbetsplatsen - att undervisa praktiker eller?

Rankic, Slavica January 2010 (has links)
Denna studie handlar om ett utbildningsprojekt som var riktat till yrkesverksamma inom vård och omsorg utan formell utbildning. Utbildningens syfte var att erbjuda deltagarna formell utbildning med utgångspunkt i deltagarnas erfarenheter samtidigt som utbildningen skulle bidra till arbetsplatsernas gemensamma lärande. Ett viktigt inslag i utbildningen var pedagogiska handledare som hade till uppgift att ge olika former av stöd till de studerande. Föreliggande studies syfte är att studera lärande i en kontext där formellt lärande interagerar med informellt och avser att ge svar på frågor om vilka förutsättningar och villkor som är nödvändiga för personalens lärande inom ramen för projektet samt hur lärandet utvecklas inom kontexten när formellt och informellt lärande samspelar med varandra. Studien bygger på intervjuer, enkäter, fokusgrupper och deltagande observationer. Resultatet visar att förutsättningarna på de olika arbetsplatserna i kombination med de studerandes individuella förutsättningar påverkar deltagarnas lärande. Studien visar också att deltagarna utvecklar olika nivåer av lärande och att dessa skillnader inte kan kopplas till antalet yrkesverksamma
40

Parenting Children with Profound Short Stature in the Post-Genomic Era

Neller, Anna Grace January 2016 (has links)
No description available.

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