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Walter, Juliane Katharina. "Charakterisierung der Struktur, Funktion und Wechselwirkungen der Tight Junction Proteine Occludin und Zonula Occludens 1." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/16012.
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Die tight junction schränken die Diffusion durch den parazellulären Raum in Epithel- und Endothelzellschichten für viele Moleküle stark ein. Dadurch behindern sie die Aufnahme von wasserlöslichen Medikamenten in das dahinterliegende Gewebe. Zwei Proteine, die am tight junction Aufbau mitwirken, sind Zonula Occludens Protein 1 (ZO-1) und Occludin. Eine Öffnung der tight junctions stellt eine Möglichkeit für die Verabreichung von Medikamenten dar. Deshalb wurden die tight junction Proteine ZO-1 und Occludin auf ihre Funktion, Struktur und Regulation untersucht. Für die Interaktion beider Proteine gab es ein Modell, welches eine Oligomerisierung der Bindungspartner als Voraussetzung ihrer Interaktion über helikale Wechselwirkungen vorhersagte. Die Annahmen aus dem Modell der Interaktion von ZO-1 und Occludin konnten experimentell bestätigt werden. Für den C-Terminus von Occludin wurde darüber hinaus eine Interaktion über Disulfidbrücken nachgewiesen. Diese Interaktion könnte in der Zelle von pathologischer Bedeutung bei Schlaganfall und Ischchämie sein. Beide Erkrankungen verursachen eine Öffnung der tight junction im Zusammenhang mit oxidativem Stress. ZO-1 bindet über PDZ Domänen eine Vielzahl von tight junction Proteinen, die an der Abdichtung des parazellulären Raums beteiligt sind. Deshalb wurde die Interaktion und Regulation der PDZ-Domänen aus ZO-1 untersucht. Eine Phosphorylierung der PDZ durch die Proteinkinase C alpha sowie eine Interaktion mit den Phosphatasen 2A und 4 konnte nachgewiesen werden. In vitro konnte gezeigt werden, dass die Phosphorylierung der PDZ-Domänen die Bindung an Membranproteine der tight junction beeinflusst. Diese Arbeit leistet einen Beitrag, die Mechanismen, die zum Verschluss des parazellulären Spaltes führen, aufzuklären. Damit zeigt sie Ansatzpunkte für eine pharmakologische Beeinflussung der Permeabilität der tight junction auf.Tight junctions restrict diffusion through the paracellular gap in endothelia and epithelia. Thereby they constrain the uptake of water soluble drugs to the tissue. Zonula occludens protein 1 (ZO-1) and occludin are some of proteins involved in tight junction assembly. The opening of tight junctions is a possibility to apply drugs. Therefore the structure, function and regulation of ZO-1 and occludin is characterised. In previous studies, a model predicted the interaction of occludin and ZO-1 through helices. It was proposed that the interaction is mediated by oligomers of ZO-1 and Occludin. This author´s experimental research supports these hypotheses. Furthermore, occludin is shown to self assemble via disulfide bridges. This interaction could be of importance during stroke and ischemia. Both diseases cause the opening of tight junctions in combination with oxidative stress. In addition, this author investigated the interaction and regulation of the PDZ domains of ZO-1. It was shown that the PDZ domains are phosphorylated by protein kinase C alpha and interact with protein phosphatases 2A and 4. Phosphorylation led to a reduction in affinity of PDZ to membrane proteins in vitro. This thesis contributes to the understanding of the mechanisms which are involved in the sealing of the paracellular gap.
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Sundstrom, Jeffrey Antonetti David A. "Identification and functional analysis of occludin phosphorylation." [University Park, Pa.] : Pennsylvania State University, 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2566/index.html.
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Andreeva, Anna. "Protein kinase C isoform antagonism controls occludin phosphorylation and tight junction assembly." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/149/index.html.
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Schmidt, Anke. "Identifizierung und Charakterisierung der Bindung zwischen dem Zonula-occludens-Protein 1 und dem Tight-junction-Protein Occludin." [S.l.] : [s.n.], 2002. http://www.diss.fu-berlin.de/2002/251/index.html.
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Ikem, Theresa. "Feedback regulation mechanisms controlling occludin expression and tight junction function." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690735.
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Cell polarity and tight junctions (TJs) are necessary for intact epithelia. Loss of tight junction integrity is consistent with a display of mesenchymal phenotype which is characteristic of metastatic progression. Occludin, the first identified transmembrane protein identified to localize at tight junctions, has been implicated in regulating tight junction function and cellular polarity. The N-terminal region of occludin has been shown to be an important factor in tight junction maintenance but the mechanism is not yet known. Extensive studies by other researchers have been performed to examine factors that drive EMT, while little is known about their functional reversibility in MET. A model system of EMT ↔ MET was previously established using Pa4 cells, an immortalized epithelial cell line derived from rat parotid gland. Stable introduction of an oncogenic form of the kinase Raf1 into Pa4 was used to derive a mesenchymal phenotype (Pa4Raf1) that demonstrates anchorage-independent growth that coincides with a loss of functional TJs including down-regulation of occludin. The N-terminal region of occludin (66 amino acids) was cloned and used as a bait to pull down protein binding partners in Pa4 and Pa4Raf1 cell lysates. This region of occludin was coupled to a hexa-histidine sequence (His-tag). The resulting protein was expressed in E. coli, purified using magnetic nickel beads, and used as a bait to pull down potential binding partners for this region of occludin present in two cell lines: Pa4 and Pa4-Raf1. Importantly, N-terminal region of occludin has a series of serine and tyrosine residues that are predicted to be phosphorylated by a wide range of kinases. In this regard, Ser8, Ser45, Tyr12, Tyr22, Tyr29 and the poly-proline region (Pro-Leu-Ser-Pro-Pro-Pro-Tyr-Arg-Pro) of the N-terminal bait peptide were mutated in order to further elucidate the functions of these residues. Serine was mutated to aspartic acid, tyrosine to glutamic acid, and proline to alanine. The binding partners were also knocked down to identify their effects on occludin colocalization. Many of the potential binding partners that were identified are involved in apoptosis, metastasis and/or cellular oxidation. This research seeks for ways by which manipulating these identified binding partners will transform a cell from a mesenchymal phenotype to an epithelial phenotype.
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Freitas, Antonio Klingem Leite de. "Efeito da SuplementaÃÃo com Alanil-Glutamina nas AlteraÃÃes da Permeabilidade Intestinal em Ratos Treinados Submetidos a um ExercÃcio Prolongado e Exaustivo de NataÃÃo." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12375.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO exercÃcio prolongado e exaustivo induz uma disfunÃÃo da barreira intestinal. VÃrios estudos mostram que a suplementaÃÃo com alanil-glutamina (A/G) melhora a proliferaÃÃo das cÃlulas intestinais e absorÃÃo de eletrÃlitos. O objetivo deste trabalho foi investigar o efeito da suplementaÃÃo com A/G na permeabilidade intestinal em ratos treinados apÃs um exercÃcio prolongado e exaustivo de nataÃÃo. Utilizamos ratos Wistar, divididos em sete grupos: 1) SedentÃrio (S); 2) SedentÃrio A/G (S-A/G); 3) Treinado (T); 4) Treinado A/G (T-A/G); 5) ExaustÃo (E); 6) ExaustÃo A/G (E-A/G) e 7) Recuperado (R). Os animais dos grupos suplementados receberam o dipeptÃdeo A/G. Os animais foram treinados durante 12 semanas de nataÃÃo. Na metodologia realizamos anÃlises bioquÃmicas de pH, pCO2, pO2, SO2, excesso de bases (BE), pelo mÃtodo de gasometria e lactato e glicose. Analisamos a transcriÃÃo das junÃÃes firmes: ZO-1, Ocludina, Claudina-2 e PEPT-1 atravÃs de RT-PCR. A anÃlise da permeabilidade intestinal foi realizada pelo mÃtodo da ingestÃo de Lactulose/Manitol (L/M). Fizemos tambÃm anÃlise histolÃgica do duodeno, jejuno e Ãleo. O presente estudo foi aprovado pela CEPA-UFC, em protocolo de N 13/13. Nossos resultados mostraram que pCO2 e SO2 foram aumentados nos grupos E e E-A/G, mas houve queda nos parÃmetros de pH e BE para estes mesmos grupos. Encontramos queda dos Ãndices de glicose e aumento das concentraÃÃes de lactato. Houve aumento significativo no percentual de excreÃÃo de lactulose nos grupos E e E-A/G em relaÃÃo ao grupo S. Houve, no entanto, queda da excreÃÃo de lactulose com diferenÃa estatÃstica entre os grupos E e E-A/G, mostrando proteÃÃo da A/G frente ao aumento da permeabilidade intestinal promovida pelo exercÃcio exaustivo. O percentual de excreÃÃo do manitol foi aumentado nos grupos E e E-A/G em relaÃÃo ao grupo S. Entretanto, na anÃlise da relaÃÃo da permeabilidade dos dois carboidratos L/M observamos um aumento significativo no grupo E em relaÃÃo ao grupo S. Contudo, houve diferenÃa significativa entre os grupos E e E-A/G mostrando que a A/G conseguiu reverter os efeitos da atividade exaustiva na permeabilidade intestinal. Observamos aumento da ZO-1 e ocludina nos grupos S-A/G e T em relaÃÃo a S. Houve tambÃm aumento de ZO-1 no grupo E em relaÃÃo ao S. PorÃm, a A/G reverteu à transcriÃÃo destas junÃÃes firmes nos grupos T-A/G e E-A/G. A transcriÃÃo de claudina-2 foi reduzida no grupo S-A/G, mas obtivemos um aumento no grupo E em relaÃÃo ao S e uma diminuiÃÃo de E-A/G em relaÃÃo ao E. Em relaÃÃo ao PEPT-1, observamos aumento da transcriÃÃo nos grupos T e E em relaÃÃo ao S. Contudo, a A/G reverteu à transcriÃÃo deste peptÃdeo no grupo E-A/G em relaÃÃo ao E. Numa anÃlise de 72 horas apÃs o teste de exaustÃo encontramos valores para a permeabilidade intestinal similares aos grupos sedentÃrios. ConcluÃmos que o exercÃcio prolongado e exaustivo alterou a permeabilidade intestinal e a suplementaÃÃo crÃnica com alanil-glutamina teve efeito protetor contra este aumento. O possÃvel mecanismo da A/G no processo estudado refere-se a processos mecÃnicos de interaÃÃo cÃlula-cÃlula (ZO-1 e ocludina) e/ou eletrolÃticos (claudina-2).
The prolonged and exhaustive exercise induces intestinal barrier dysfunction. Several studies show that supplementation with alanyl-glutamine (A/G) improves the cell proliferation intestinal and electrolyte absorption. The aim of our study was to investigate the effect of supplementation with A/G in the intestinal permeability in rats trained after prolonged exercise and exhaustive swimming. We used Wistar rats that were divided into seven groups: 1) Sedentary (S); 2) Sedentary A/G (S-A/G); 3) Trained (T); 4) Trained A/G (T-A/G); 5) Exhaustion (E); 6) Exhaustion A/G (E-A/G); 7) Recovered (R). The animal supplemented groups received the dipeptide A/G. The animals were trained for twelve weeks. In the methodology we performed biochemical analysis of pH, pCO2, pO2, SO2, and bases excess (BE), by the method of gas analysis and lactate and glucose. We analyzed the transcription of tight junctions: ZO-1, Occludin, Claudin-2 and PEPT-1 by RT-PCR. The analysis of intestinal permeability was performed by the method of the ingestion of lactulose/mannitol (L/M). We also performed histological analysis of the duodenum, jejunum and ileum. This study was approved by the CEPA-UFC on Protocol NÂ 13/2013. Our results showed that SO2 and pCO2 were higher in groups E and E-A/G, but decreased the parameters pH and BE for these same groups. We found falling glucose levels and increased concentrations of lactate. A significant increase in the percentage of excretion of lactulose in groups E and E-A/G than in group S. There was, however, fall of excretion of lactulose with statistical difference between groups E and E-A/G, showing protection against the alanyl-glutamine increased intestinal permeability promoted by exhaustive exercise. The percentage of excretion of mannitol was increased in groups E and E-A/G than in group S. However, in the analysis of the excretion of both carbohydrates lactulose/mannitol we observed a significant increase in group E than in group S. However, there was significant difference between groups E and E-A/G showing that Ala/Gln was able to reverse the effects of exhaustive activity in intestinal permeability. We observed an increase in ZO-1 and occludin in groups S-A/G and T with respect to S. There was also an increase of ZO-1 in the E group compared to S. However, Ala/Gln reversed the transcription of these tight junctions in groups T-A/G and E-A/G. Transcription of claudin-2 was reduced in the S-A/G, but we obtained and increase in the E group compared to a decrease of S and E-A/G against E. Regarding the PET-1 we showed increased transcription in groups T and E in relation to S. However, the Ala/Gln reversed the transcript of this dipeptide in group E-A/G with respect to E. An analysis 72 hours after the exhaustion test values found for intestinal permeability similar to sedentary group. The prolonged and exhaustive exercise altered intestinal permeability and chronic supplementation with Ala/Gln was protective against the increase. The possible mechanism of Ala/Gln refers to mechanical processes of cell-to-cell interaction (occludin and ZO-1) and/or electrolytic (claudin-2).
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Dörfel, Max J. [Verfasser]. "Der Einfluss posttranslationaler Modifikationen auf die Funktion des Tight Junction-Proteins Occludin / Max Dörfel." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1027498493/34.
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Castro, Villela Víctor Manuel [Verfasser]. "The interplay between occludin and ZO-1 is redox sensitive / Víctor Manuel Castro Villela." Berlin : Freie Universität Berlin, 2011. http://d-nb.info/1026358752/34.
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Neophytou, Irene. "Expression and characterisation of peptides based on the predicted extracellular domains of human occludin." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406444.
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Saitou, Mitinori. "Occludin-deficient Embryonic Stem Cells Can Differentiate into Polarized Epithelial Cells Bearing Tight Junctions." Kyoto University, 1999. http://hdl.handle.net/2433/181723.
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Lochhead, Jeffrey James. "Oxidative Stress Alters Blood-Brain Barrier Integrity." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/193873.
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The blood-brain barrier (BBB) is located at the level of the cerebral microvasculature and is critical to maintain central nervous system (CNS) homeostasis. The tight junction (TJ) protein complexes between endothelial cells at the BBB are primarily responsible for limiting paracellular diffusion of substances from the blood to the CNS. The BBB’s functional integrity is compromised in a number of disease states which affect the CNS, suggesting BBB dysfunction causes or contributes to many diseases of the CNS. A common component of most of these diseases is oxidative stres. Oxidative stress is associated with hypoxia-reoxygenation (HR) and peripheral inflammatory pain (PIP). Both HR and PIP have been shown to compromise BBB functional integrity. Using in vivo rat models of HR and PIP, we examined the role of ROS on BBB permeability as well as the TJ protein occludin using the free radical scavenger tempol. First, we subjected rats to HR with or without pre-treatment with tempol (200 mg/kg). We showed that tempol prevents up-regulation of the cellular stress marker heat shock protein 70 at the BBB during HR. Next we showed tempol reverses HR-mediated BBB permeability increase to ¹⁴C-sucrose, a marker of BBB paracellular permeability. Tempol also attenuated changes in the structure and localization of occludin, suggesting ROS produced during HR alter occludin and lead to disruption of BBB. We then investigated whether ROS production have similar effects on occludin and BBB permeability during PIP by administering 3% λ-carrageenan into the hind paw of rats. We found tempol attenuated carrageenan-induced increase in paw edema and thermal hyperalgesia. Tempol also attenuated up-regulation of the cellular stress marker NF-κB in cerebral microvessels. Tempol significantly decreased BBB permeability to ¹⁴C sucrose during PIP. We found PIP reduces disulfide bonds in occludin oligomeric assemblies thought to be important in maintaining the structural integrity of the BBB. Tempol significantly inhibited disulfide bond reduction, suggesting ROS mediate BBB disruption during inflammatory pain by reducing occludin disulfide bonding. Taken together, these findings show the involvement of ROS during HR and PIP contributes to BBB dysfunction by altering the structure of high molecular weight occludin oligomeric assemblies.
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Bellmann, Christian [Verfasser]. "Struktur und Funktion des tight junction-Proteins Occludin unter normoxischen und hypoxischen Bedingungen / Christian Bellmann." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1052020844/34.
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Hau, Vincent Sinh. "EFFECT OF PERIPHERAL INFLAMMATORY PAIN ON THE BLOOD-BRAIN BARRIER." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1071%5F1%5Fm.pdf&type=application/pdf.
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Moroi, Seiji. "Occludin is concentrated at tight junctions of mouse/rat but not human/guinea pig Sertoli cells in testes." Kyoto University, 2000. http://hdl.handle.net/2433/180874.
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McCabe, Mark James, and markmccabe02@hotmail com. "Hormonal regulation of the testicular Sertoli cell tight junction." RMIT University. Applied Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081212.100348.
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The Sertoli cell tight junction (TJ) of the seminiferous epithelium is important for the developmental process of spermatogenesis as it separates germ cells in the seminiferous tubules from the general circulation in the testicular interstitium. Absence of the TJ leads to spermatogenic arrest and infertility. TJs form at puberty as circulating gonadotrophins luteinising hormone/testosterone and follicle stimulating hormone increase. Several studies have demonstrated hormonal regulation of the two major TJ proteins, claudin-11 and occludin, and also of TJ function in vitro and in vivo. Men with low levels of circulating gonadotrophins exhibit an immature and dysfunctional TJ phenotype, which is reversed upon the exogenous application of gonadotrophins. This thesis hypothesises that claudin-11 and occludin are the major contributors to TJ function, and that gonadotrophins regulate TJ function and structure via these two proteins in several species including humans. This PhD was divided into four separate studies to address these hypotheses. The first study selectively silenced the genetic expression of claudin-11 and occludin with small interfering RNA (siRNA) in cultured immature rat Sertoli cells to determine their contribution to Sertoli cell TJ function in vitro. siRNA treatment against either protein significantly (p less than 0.01) reduced TJ function by ~50% as assessed by transepithelial electrical resistance. Immunocytochemistry displayed marked reductions in the localisation of these proteins to the TJ after siRNA treatment. It was concluded that both proteins significantly contributed to TJ function in vitro. The second and third studies then aimed to study hormonal regulation of the TJ in vivo. Weekly injections of the gonadotrophin releasing hormone antagonist acyline were used to suppress circulating gonadotrophins and spermatogenesis in adult rats. Acyline treatment disrupted i) the localisation of occludin to the TJ and ii) TJ function as shown by permeability to a biotin tracer, which was impermeable to TJs in controls. Short-term hormone replacement partially restored the effects of gonadotrophin suppression. It was concluded that gonadotrophins regulate the maintenance of the TJ in rats in vivo. The third study used the hypogonadal (hpg) mouse, which is a naturally occurring model of gonadotrophin deficiency with inactive spermatogenesis. Claudin-11 in hpg mice was not localised at the TJs, and these were dysfunctional as shown by permeability to biotin. Following hormone treatment, TJs were structurally and functionally competent, demonstrating that gonadotrophins also regulate the formation of TJs in vivo. The fourth study subsequently analysed TJs in gonadotrophin suppressed men, and it was found that claudin-11 staining was reduced from continuous bands in control men, to punctate staining in gonadotrophin-suppressed men, demonstrating that gonadotrophins also regulate the localisation of claudin-11 to the TJ in men in vivo. In summary, it is concluded that the Sertoli cell TJ is hormonally regulated, and that the major contributors to TJ function in vivo and in vitro are claudin-11 and occludin. It is hypothesised that the reduction of claudin-11 localisation to the TJ in men may also result in a loss of human Sertoli cell TJ function, suggesting that the TJ may be a potential target of hormonal contraception in men.
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Koivukangas, V. (Vesa). "Wound healing in a suction blister model:an experimental study with special reference to healing in patients with diabetes and patients with obstructive jaundice." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514275810.
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Abstract
The expression intensities of cytokeratins and tight junction proteins were determined on re-epithelization. Experimental blister wound healing was studied in patients with diabetes mellitus and in patients with obstructive jaundice.
Suction blisters were induced on healthy volunteers, and the healing blisters were biopsied at different time points. Cytokeratin expression and the tight junction proteins ZO-1 and occludin were studied immunohistochemically.
Blisters were induced on 17 patients with diabetes and 11 control subjects, and the healing process was followed indirectly by measuring water evaporation and blood flow in the wounds. Microvascular reactivity in the diabetic patients was also studied by using non-immunologic contact irritants.
Wound healing, skin collagen synthesis and serum levels of procollagen propeptides were studied in 24 patients with obstructive jaundice caused by neoplastic pancreaticobiliary obstruction and in 17 control patients with the corresponding condition without jaundice.
Cytokeratin expression was altered in healing epidermis. In the suprabasal layer, K10 was replaced by K14 and, most likely, by K16. K18 keratin, which is not present in normal epidermis, was found in the basal and suprabasal layers. Thus, there was a shift towards lower molecular weight cytokeratins, which is a reflection of immaturity, and probably towards motility. The tight junction proteins ZO-1 and occludin were expressed in the migrating epidermal sheet, where they apparently form an early barrier. Enhanced expression was seen in the hyperproliferative zone of the wound edge.
The diabetic patients showed slower restoration of the epidermal barrier and a weaker initial inflammatory response. Obstructive jaundice and its resolution had no effect on healing.
Skin collagen synthesis was decreased in jaundiced patients, and it increased slightly after drainage. Serum type III collagen propeptide levels were elevated in patients with biliary obstruction and dropped after drainage. The elevated levels may be related to the increased synthesis due to fibrosis.
As a conclusion, diabetes mellitus impairs epidermal wound healing, while obstructive jaundice does not.
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Le, Nga Thi Thanh. "Regulation of Intestinal Epithelial Barrier and Immune Function by Activated T Cells." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1599833768774075.
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Jones, Emily. "Maintaining the intestinal barrier : the role of the tight junction protein occludin in Toxoplasma gondii transmigration of the gastrointestinal tract." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/61413/.
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The small intestinal permeability barrier is dependent on tight junction (TJ) complexes that separate the external lumen from the underlying mucosa. Apical TJs consist of integral transmembrane proteins including occludin, claudins and ZO-1 as well as the cytoplasmic plaque of TJ-associated adaptor, scaffolding and signalling proteins. Although the function of occludin at the TJ remains unclear, the dynamic mobility of occludin, claudins and ZO-1 to and from the TJ suggests occludin may play a key role in regulation of TJ structure and function, regulated by occludin phosphorylation status. Defects in TJ barrier function have been implicated in a range of inflammatory diseases such as inflammatory bowel disease (IBD) and pathogens such as Toxoplasma gondii target this complex as a route of infection. As oral infection is the primary cause of toxoplasmosis, the first point of contact between T. gondii and the host is the small intestinal epithelium and studies by Weight, 2012 show occludin may be involved in T. gondii paracellular transmigration of the small intestinal epithelium. The aim of this research was to investigate T. gondii paracellular transmigration using an in vitro model of the small intestinal epithelium and elucidate the role of occludin both in regulation of the TJ barrier and as a receptor for T. gondii infection. The results presented in this thesis demonstrate that T. gondii infects the small intestinal epithelium via the paracellular pathway and occludin was shown to play a key role both in regulation of the TJ paracellular barrier and as a receptor for T. gondii infection by parasite-mediated modulation of the occludin C-terminus phosphorylation status and direct binding to occludin ECL1; suggesting T. gondii interactions with occludin are a potential mechanism of paracellular transmigration of the small intestinal epithelium.
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NASCIMENTO, Aline Machado Rapello do. "Lesões de isquemia arteriovenosa e reperfusão em jejuno de equinos: imunoistoquímica de proteínas de junção e histopatologia." Universidade Federal de Goiás, 2007. http://repositorio.bc.ufg.br/tede/handle/tde/397.
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Previous issue date: 2007-12-31To evaluate whether complete arteriovenous ischemia followed by reperfusion of mesenteric blood flow aggravates lesions involving small intestine of horses, β--catenin and occludin expressions were measured in jejune epithelia of seven equines, without definite breed. The animals had been submitted to aseptic ventral midline celiotomy and five jejune segments collected corresponding to a baseline segment, a five minutes segment subjected to ischemia, and three segments collected after being subjected to five, sixty and one hundred and twenty minutes of tecidual reperfusion, respectively. Experimentally induced lesions created by total arteriovenous occlusion followed by reperfusion were similar to naturally acquired lesions, as much in the period of ischemia as in the aggravation of the injuries observed during reperfusion. Changes that occur when ischemic intestine is reperfused are progressive, and include mucosal, submucosal, and serosal edema; polymorphonuclear and mononuclear cell infiltrates; and alterations in vascular patterns. Imunohistochemistry analyses have shown strong staining baseline segments for β-catenin in all animals and its progressive lack of staining during ischemia and reperfusion treatments. That indicates progressive lack of intercellular adherence. Similar results of specific decreases of total expression of Occludin, a tight junction protein, were observed. This protein is involved in regulating the movement of solutes in the paracellular pathway and also plays an important role in the maintenance of cell polarity. The reduction of expressions of both intercellular proteins measured directly demonstrates β-catenin injury due to progression of edema during ischemia and its aggravation during reperfusion and also shows an increase of the permeability of paracelular pathways and its related consequences to degradation of Ocludina.
Realizou-se o estudo da patogenia da lesão por isquemia arteriovenosa completa dos vasos mesentéricos e reperfusão jejunal em eqüinos por meio da avaliação da expressão das proteínas β-catenina e ocludina presentes neste epitélio, em sete eqüinos, sem raça definida. Os animais foram submetidos á celiotomia asséptica na linha alba e coleta de cinco segmentos jejunais correspondestes á um segmento controle, um segmento tratado com isquemia por cinco minutos, e três segmentos coletados durante o período de reperfusão tecidual aos cinco, sessenta e cento e vinte minutos, respectivamente. As lesões induzidas experimentalmente por oclusão arteriovenosa total seguida por reperfusão foram similares às lesões adquiridas naturalmente tanto no período de isquemia quanto no agravamento das lesões observado nos tempos de reperfusão. As mudanças que ocorrem quando um intestino isquêmico sofre reperfusão são progressivas e incluem edema de mucosa, submucosa e serosa, infiltração polimorfonuclear e mononuclear e alterações nos padrões vasculares. A análise imunoistoquímica revelou forte expressão da β- catenina em todos os animais e a sua progressiva perda da expressão quando submetidos à isquemia e reperfusão. Isso indica perda progressiva da adesividade intercelular. Resultados similares de redução do total da expressão da Ocludina, uma proteína de junção de oclusão, foram observados. Esta proteína está envolvida na regulação dos movimentos dos solutos na via paracelular e também desempenha um importante papel na manutenção da polaridade celular. A diminuição da expressão de ambas as proteínas intercelulares demonstra a lesão à β-catenina devido à progressão do edema durante isquemia e o agravamento durante a reperfusão tecidual e também mostra um aumento na permeabilidade da via paracelular e suas conseqüências relacionadas à degradação da Ocludina.
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Volksdorf, Thomas [Verfasser], and Johanna [Akademischer Betreuer] Brandner. "Die Rolle der Tight-Junction-Proteine Claudin-1, Occludin und ZO-1 in nativer und gestörter epidermaler Wundheilung / Thomas Volksdorf ; Betreuer: Johanna Brandner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/1135386579/34.
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Pond, Emma. "Characterisation of tight junctions in polymorphic light eruption." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-tight-junctions-in-polymorphic-light-eruption(8d043c3d-7f97-41e1-9b87-9523c5b639d6).html.
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Polymorphic light eruption (PLE) is the most common photodermatosis, affecting ~17% of the population. PLE is a delayed-type hypersensitivity response to an antigen induced by solar ultra-violet radiation (UVR). Its effects vary between patients, but the main symptom is a non-scarring, red papular rash in areas exposed to UVR. An effective therapy is low dose ultra-violet B (NBUVB) phototherapy. It is thought that NBUVB phototherapy desensitises the skin to further UVR exposure, but the mechanism by which this happens is unknown. Current immune based studies have been unable to clarify a mechanism as to how PLE arises. However, research in other skin diseases, such as psoriasis and atopic dermatitis, has shown that the barrier function of the skin is compromised by these disorders. Furthermore, research in lesional PLE skin showed an increase in barrier permeability of the skin. Recent research has specifically linked claudin proteins of tight junctions to the barrier dysfunction. Therefore, this study used quantitative immunofluorescent staining to measure tight junction (TJ) proteins and other barrier proteins of interest. Barrier function was also measured by transepidermal water loss (TEWL); a tracer dye penetration assay was used to measure TJ barrier function specifically. All measurements were made in non-lesional PLE skin, as compared to skin from healthy human volunteers. In photoprotected PLE skin the TJ protein claudin-1 was significantly reduced compared to healthy skin. The use of a tracer dye highlighted there was a reduction in TJ barrier function in PLE skin compared to healthy individuals. PLE and healthy skin were then exposed to ultra-violet B (UVB) and 24h later TJ proteins and TJ barrier function were measured. There was no change to claudin-1 after UVB exposure in PLE skin, but claudin-7 was reduced and claudin-12 increased. In contrast, in UVB-irradiated skin in normal controls after UVB exposure claudin-7 and claudin-12 were both increased, whilst claudin-1 was reduced. In PLE patients there was no further change to TJ barrier function, however, in normal controls, skin TJ barrier function was reduced post UVB. Both in healthy and PLE skin TEWL was unchanged before and after UVB exposure. Lastly TJ proteins were investigated after NBUVB in PLE patients. There was a further reduction in claudin-1 in PLE patients as well as a reduction in the TJ protein occludin, however the stratum corneum was significantly thickened. It could be suggested that this is a compensatory measure for the reduction seen in TJ barrier proteins, however further studies are needed to understand this. These data show significant differences in the TJ skin barrier in patients with PLE as compared to healthy human volunteers before and after UVB exposure. Furthermore, in PLE skin there is a significant change to the epidermis after NBUVB phototherapy. These data demonstrate that TJ protein expression and function is altered in PLE skin and may contribute to aetiology of the disorder, however the role of TJ barrier in aetiology is yet to be firmly established.
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Karlsson, Mattias. "Evaluation of Object-Space Occlusion Culling with Occluder Fusion." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-13055.
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In this report, an object-space solution to occluder fusion of OBB occluders is explored. Two different approaches are considered were the object-space fusion is reduced to a 2D problem. The first approach finds axis-aligned silhouettes within the projection of occluder OBBs which are then fused together creating large axis-aligned silhouettes. The other approach creates concave hulls of the projected OBB silhouettes from which convex inscribed silhouettes are then found. These silhouettes are then converted back to object-space where shadow frusta created around the silhouettes are used for the culling operation. The effectiveness of the two approaches is evaluated considering the amount of culled geometry. It is shown that fused convex silhouettes are needed to produce competitive results.
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Boström, Caroline. "Investigation on Cell-Cell Junctions by Inhibition of Na,K-ATPase Activity." Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298360.
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This thesis report investigates the effect on cellcell junction proteins when the Na,K-ATPase (NKA) is inhibited. The main goal is to develop an understanding of how the NKA activity regulates the cell junction proteins. The investigated proteins are the adherens junction protein ECadherin, and the tight junction proteins Occludin and Claudin7.The NKA is inhibited by introducing the cardiotonic steroid Ouabain to the cells. The treatment is tested for different time lapse and different concentrations. The results show that all proteins are down regulated when treated with high concentrations (500 nM) of Ouabain. ECadherin is up regulated when treated with lower concentrations (10 nM) of Ouabain while Claudin7 is down regulated at low levels.Detta examensarbete undersöker effekten på cell-cell junctions när Na,K-ATPas (NKA) inhiberas. Målet med rapporten är att få en förståelse för hur NKA aktiviteten reglerar cell-cell junction proteinerna. Proteinerna som undersöks är adherens junction proteinet ECadherin, och tight junction proteinerna Claudin7 och Occludin. NKA inhiberas genom att cellerna behandlas med den kardiotoniska steroiden Ouabain. Behandlingen testas under olika tidsperioder och för olika koncentrationer. Resultaten visar att alla proteiner är nedreglerade när de behandlas med höga koncentrationer (500 nM) av Ouabain. ECadherin blir uppreglerad när det behandlas med lägre koncentrationer (10 nM) av Ouabain medan Claudin7 nedregleras vid låga nivåer.
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Hollén, Elisabet. "Coeliac Disease in Childhood : On the Intestinal Mucosa and the Use of Oats." Doctoral thesis, Linköpings universitet, Medicinsk mikrobiologi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7690.
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Celiaki, eller glutenintolerans, är en av våra vanligaste kroniska sjukdomar i barnaåren. Sjukdomen orsakar en kraftig inflammation i tunntarmens slemhinna efter intag av glutenhaltig föda hos personer med ärftlig benägenhet att utveckla celiaki. En frisk tarm är kraftigt veckad för att öka ytan för upptag av näringsämnen. Ytan består dessutom av åtskilliga fingerliknande utskott, s.k. villi, och mellan villi finns kryptorna där celldelning och celldifferentiering sker. Villi och kryptor kantas av epitelceller, enterocyter, vilkas uppgift är att ta upp näring från tarminnehållet samt att utgöra en selektiv barriär mellan den yttre och inre miljön i tarmen. Den typiska tarmskadan vid celiaki karakteriseras av avsaknad av villi och kraftigt förlängda kryptor, och både näringsupptaget och barriärfunktionen är dessutom störda. Den enda behandling som finns att tillgå vid celiaki är en livslång glutenfri diet. De skadliga proteinerna i vetegluten kallas gliadin, och det finns liknande proteiner i råg, korn, och havre. I havre kallas proteinet avenin. Möjligheten att använda havre vid celiaki har diskuterats flitigt, men numera anses det riskfritt för majoriteten av både barn och vuxna att använda havre i den glutenfria dieten. Målet med den här avhandlingen var att undersöka hur barn med celiaki reagerar på havre i kosten. Detta studerades med avseende på antikroppar mot avenin samt med en metod som mäter halten av kväveoxid- (NO-) produkter i urinen. Ett andra mål var att studera tunntarmens struktur vid olika stadier av celiaki. I den första studien undersökte vi om celiakibarn har antikroppar i serum mot avenin. Vi fann att så var fallet och att nivåerna var signifikant högre än hos friska kontrollbarn. När barnen sattes på glutenfri kost sjönk antikroppsnivåerna, för att öka igen när gluten återinfördes i kosten. Blodproverna till den här studien togs innan debatten om havre kom igång, vilket gör att vi tror att de olika dieterna även speglar ett sant intag av havre. Studien visade också att det inte var någon korsreaktion mellan antikroppar mot avenin och gliadin. Vi använde sedan vår metod för att mäta antikroppar mot avenin i en randomiserad studie där havre gavs till barn med nydiagnostiserad celiaki. Barnen fick antingen en vanlig glutenfri diet eller en med tillsats av specialhavre. Antikroppsnivåerna sjönk markant redan efter tre månader i båda grupperna, och vid studietidens slut, efter ca ett år, hade alla utom ett par patienter återfått normala nivåer. Samma barn studerades även med avseende på NO-produkter i urinen. NO är en kortlivad molekyl som fungerar som budbärare i och mellan celler, och produktionen av den ökar markant vid en inflammation. Tidigare studier har visat att barn med obehandlad celiaki har extremt höga halter av NO-produkter i urinen. I vår studie sjönk även dessa värden signifikant efter tre månader, och det var ingen skillnad mellan grupperna. Efter ett år hade dock fyra barn i havregruppen och ett barn i den grupp som fick vanlig glutenfri kost, fortfarande extremt höga nivåer av NO-produkter. Dessa båda studier styrker den kliniska uppfattningen att de flesta barn med celiaki kan tåla havre, men de visar också att man bör följa upp de celiakibarn som kompletterar sin glutenfria kost med havre eftersom vissa barn verkar ha kvarstående tecken på inflammation i tarmen. I tarmbiopsier från barn med olika stadier av celiaki studerades förekomst och lokalisering av occludin och claudiner, proteiner som är viktiga för att upprätthålla barriärfunktionen i tarmen. Vi fann ett ökat uttryck av occludin vid obehandlad celiaki, vilket vi tror speglar den ökade celldelning och de förändrade barriäregenskaper som man ser vid aktiv celiaki. Resultaten tyder även på att uttrycket av claudin 1-5 inte tycks påverkas av kosten hos barn med celiaki.Coeliac disease (CD) is one of our most common chronic diseases in childhood. The disease causes an intense inflammation in the small intestinal mucosa after ingestion of gluten-containing cereals in genetically predisposed individuals. The mucosal lesion in CD is characterised by villous atrophy and crypt hyperplasia, and both the absorptive and the barrier functions of the enterocytes are disturbed. The treatment of CD is a life-long adherence to a gluten-free diet (GFD). The toxic fraction of wheat gluten is gliadin, and there are similar proteins in rye, barley and oats. In oats this protein is called avenin, and it is proposed to be less toxic than the others. The use of oats in CD has been debated, but it is now considered safe for the majority of both children and adults with CD. The aims of this thesis were to investigate the humoral and inflammatory reactions to oats in children with CD, and also to study the intestinal mucosa at different stages of the disease. In a retrospective study we found that children with CD had antibodies to oats avenin, and that the levels were significantly higher than in controls. The levels attenuated during GFD, and we also showed that there was no crossreactivity between antibodies to oats and gliadin. We then used our method for measuring antibodies to avenin in a randomised, double-blind trial of oats given to children with newly diagnosed CD. The children were given either a traditional GFD or a GFD supplemented with oats. There was a rapid decrease in antibody levels in both groups already after three months on diet, and at the end of the study period all but a few had normalised their levels. The same children were also studied using urinary nitric oxide (NO) products as markers for intestinal inflammation. Likewise, these values decreased significantly after three months. At the end of the study four children in the GFD-oats group and one in the standard GFD group still had extremely high concentrations of urinary NO metabolites. Taken together, these studies strengthen the clinical impression that oats can be tolerated by the majority of children with CD, but they also warrant a caution, since there seem to be children that do not tolerate oats in their diet. The structure and distribution of occludin and claudins 1-5, tight junction proteins known to play a crucial role in maintaining the barrier function, was studied in biopsy specimens from children at different stages of CD. There was an increased expression of occludin in untreated CD, which reflects the characteristics of crypt cell hyperplasia and altered barrier properties seen in active CD. The findings also indicate that gluten intake does not significantly influence the expression and distribution of claudins 1-5 in coeliac children.
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Schneider, Hannah Adelheid [Verfasser], Annette Margarete [Akademischer Betreuer] Müller, and y. Rotaeche Josune [Akademischer Betreuer] Guzman. "Expression von AP2-gamma, p53 und Occludin in Plazenten von Raucherinnen und von Patientinnen mit Präeklampsie / Hannah Adelheid Schneider. Gutachter: Annette Margarete Müller ; Josune Guzman y Rotaeche." Bochum : Ruhr-Universität Bochum, 2015. http://d-nb.info/1079843485/34.
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Yi, Sheng. "Synthetic peptides modulate epithelial junctions." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2344.
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Hahn-Strömberg, Victoria. "Cell adhesion proteins in different invasive patterns of colon carcinomas : a morphometric and molecular genetic study." Doctoral thesis, Örebro universitet, Hälsoakademin, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2603.
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Colorectal carcinoma is the second most common type of cancer in both men and women in Sweden. Cancer of the colon and rectum are often considered together and their ten year survival rate is approximately 50 – 60 % depending on sex and location. Different histopathological characteristics of such cancers, including the complexity of growth, are of importance for prognosis. This thesis has compared different morphometric methods in order to achieve a quantitative and objective measurement of the invasive front of colon carcinoma. Since the growth pattern is dependent on the cell adhesiveness of different proteins we studied the distribution and localization of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin as well as screened the genes for mutations. We found a perturbed protein expression of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin in tumor sections compared to normal mucosa, but no relation to tumor volume or growth pattern could be seen. The tumor volume was found to be correlated to the growth pattern but not responsible to the perturbed protein expression. In the mutation screening we found a SNP in exon 13 the E-cadherin gene in the tumor, as well as in exon 2 of Claudin 1 and exon 4 of Claudin 7 in both tumor and normal mucosa. No correlation between mutations and growth pattern or tumor volume was found. In conclusion, this thesis shows that the computer image analysis with estimation of fractal dimension and number of free tumor cell clusters is superior to the semi quantitative visual grading of tumor invasive complexity. The aberrant expression of cell adhesion proteins in the tumor compared to normal mucosa as well as polymorphisms in the cell adhesion genes CLDN1 and CLDN7 in both tumor and normal mucosa can suggest that these aberrations are important in the tumorigenesis of colon carcinoma.
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Gläser, Theresa Constanze Pilar [Verfasser], and Wolfgang [Akademischer Betreuer] Scheppach. "Modulation der Expression der tight junctions in epithelialen Monolayern als Antwort auf exogene Faktoren anhand der Untersuchung zweier Proteine Occludin und ZO-1 / Theresa Constanze Pilar Gläser, geb. Marbe. Betreuer: Wolfgang Scheppach." Würzburg : Universitätsbibliothek der Universität Würzburg, 2012. http://d-nb.info/1022061259/34.
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Röhrs, Lena [Verfasser]. "Untersuchungen der Blut-Hoden-Schranke während der Rekrudeszenz der Spermatogenese nach Downregulation mittels eines slow release GnRH-Implantates beim Rüden : Expression von Connexin 43, Occludin, Claudin-3, -5 und -11 / Lena Röhrs." Gießen : Universitätsbibliothek, 2014. http://d-nb.info/1068275855/34.
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Clement, Camille. "Etude de la dynamique spatiotemporelle des interactions VHC-récepteurs." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ098.
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Pour infecter les hépatocytes le virus de l'hépatite C (VHC) interagit avec de nombreux facteurs d’entrées et la dynamique d’interaction du VHC avec ces récepteurs lui permettra d’entrer dans la cellule. Parmi eux, Claudin 1 (CLDN1) et Occludin (OCLN), des protéines majeures composant les jonctions serrées (TJs). La dynamique d’interaction spatiotemporelle et ainsi que le lieu de l’interaction restent controversés. Durant ce travail de thèse j’ai utilisé l’imagerie sur cellule vivante pour étudier cette dynamique d’interaction.J’ai développé des outils biologiques pour l’imagerie et ainsi généré plusieurs lignées cellulaires exprimant à un niveau endogène l’OCLN et la CLDN1 en fusion à une étiquette et obtenue du VHC fluorescent. L’imagerie sur cellules vivantes et le suivie de particules virales uniques a démonté que l’interaction VHC-OCLN se faisait en dehors de TJs et que l’OCLN semblerait stabiliser le complexe VHC-récepteurs pour permettre son endocytoseTo infect hepatocytes the hepatitis C virus (HCV) interacts with many entry factors and thedynamics of HCV interaction with these receptors lead to virus uptake. Among them,Claudin 1 (CLDN1) and Occludin (OCLN), major proteins composing the tight junctions(TJs). The dynamics of spatiotemporal interaction and the location of the interaction remainunclear and controversial. During my pHD I used live cell imaging to study spatiotemporaldynamics of HCV-receptors. I developed biological imaging tools and generated several celllines that endogenously expressed OCLN and CLDN1 fused to a fluorescent tag andlabeled HCV particles. Live cell imaging and tracking of single viral particles demonstratedthat the HCV-OCLN interaction occurs outside of TJs and that the OCLN seems to stabilizethe HCV-receptor complex to allow its uptake in the cell
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Scheffer, David [Verfasser], Carola [Gutachter] Förster, Srikanth [Gutachter] Karnati, and Philip [Gutachter] Tovote. "Einfluss einer Dexamethason/Bortezomib-Kombinationstherapie auf den Glukokortikoidrezeptor und die Tight Junction-Moleküle Claudin-5 und Occludin in Endothelzellen der Blut-Hirn-Schranke in experimentellen Modellen des Schädel-Hirn-Traumas / David Scheffer ; Gutachter: Carola Förster, Srikanth Karnati, Philip Tovote." Würzburg : Universität Würzburg, 2020. http://d-nb.info/1223851362/34.
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Laat, A. De. "Masseteric reflexes and their relationship towards occlusion and temporomandibular joint dysfunction." Leuven, Belgium : Catholic University of leuven, Faculty of Medicine, School of Dentistry, Oral Pathology and Oral Suregry, 1985. http://catalog.hathitrust.org/api/volumes/oclc/38265081.html.
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Niyogi, Sourabh A. "Kinetic occlusion." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/37545.
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Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 58-66).
by Sourabh Arun Niyogi.
Elec.E.
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Chiu, C. C. "Detection of occluding boundaries in spatiotemporal images." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597617.
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The extraction of occluding contours - projection of depth discontinuities - in unstructured scenes is one of the most important unresolved problems in computer vision research. Traditionally, occlusion is studied in static images in the context of T-junction analysis, object segmentation, or stereo. In this thesis, we motivate the use of deliberate but constrained viewer motion to make explicit the dynamic properties of occluding contours; namely, motion parallax and accretion/deletion of image texture. We examine long, densely-sampled image sequences in order to capture the spatiotemporal coherence of moving images, and thus eliminating the correspondence problem. Two methods of occlusion detection are proposed: the first is based on locally finding spatiotemporal junctions; the second is based on extracting long-range spatiotemporal trajectories and finding their intersections. Regarding the first method, we conjecture that occlusion detection is a local operation which can be achieved by spatiotemporal filters of finite support. We compute a coherence measure which quantifies how well the local spatiotemporal structure is aligned. Occlusion events are then signalled by a drop of the coherence value. In order to study the error performance of this operator, we conduct a Monte Carlo simulation using a large number of synthetic, but realistic, spatiotemporal images. The results show that our detector gives reasonable response in many cases, but the detection rate and localisation accuracy are not entirely satisfactory. The second method is concerned with fitting straight lines to spatiotemporal images and finding their intersections.
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Clairembault, Thomas. "Caractérisation de l'atteinte de l'unité neuro-glioépithéliale entérique dans la maladie de Parkinson à travers l'utilisation de biopsies épithéliales coliques humaines." Nantes, 2015. http://archive.bu.univ-nantes.fr/pollux/show.action?id=cbb79cac-c1a4-4413-9bd9-e236006110d1.
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Des altérations fonctionnelles et morphologiques de l'unité neuro-glio-épithéliale (UNGE) entérique sont décrites depuis longtemps dans des pathologies digestives comme le syndrome de l'intestin irritable ou les maladies inflammatoires chroniques de l'intestin. Il est désormais bien établi que la maladie de Parkinson (MP) n'est pas seulement une maladie du cerveau mais est aussi une maladie digestive. Les symptômes gastro-intestinaux sont fréquents et prématurés dans la MP et ils pourraient être impliqués de façon critique dans le développement précoce de la maladie. Dans la MP les neurones entériques accumulent de l'α-synucléine, la signature spécifique de la MP, c'est la raison pour laquelle nous avons enquêté à travers ce travail de thèse sur la réactivité gliale entérique en évaluant les niveaux d'expression et de phosphorylation de la protéine GFAP dans des biopsies coliques de parkinsoniens. En parallèle nous avons également étudié les éventuelles altérations des fonctions et de morphologie de la barrière épithéliale intestinale (BEI) en mesurant les perméabilités para- et transcellulaires dans les biopsies coliques et en évaluant l'expression et la localisation cellulaire de deux protéines des jonctions serrées ZO-1 et l'occludine. Comparés aux contrôles, les parkinsoniens avaient une surexpression significative de la GFAP entérique alors que les niveaux de phosphorylation sur la sérine 13 étaient significativement plus bas. Les perméabilités para- et transcellulaires n'étaient pas modifées chez les parkinsoniens. L'expression de l'occludine, mais pas de ZO-1, était significativement plus basse chez les patients MP comparés aux témoins et la localisation cellulaire de ces deux protéines était altérée chez les parkinsoniens. Nos données apportent ainsi de nouvelles preuves sur l'atteinte de l'UNGE dans la MP via l'accumulation d'α-synucléine dans les neurones entériques, l'activation gliale entérique et les altérations morphologiques de la BEI. Ce travail de thèse renforce ainsi le rôle potentiel joué par le tube digestif dans l'initiation et/ou la progression de la MPFunctionnal and morphological alterations of the enteric neuro-glio-epithelial unit (NGEU) have been consistently reported in digestive disorders such as irritable bowel syndrome or inflammatory bowel disease. There is mounting evidence that Parkinson's disease (PD) is not only a brain disease but also a gut disorder. Gastrointestinal involvement is a frequent and early event in the course of PD, and it may be critically involved in the early development of the disease. As in PD the enteric neurons accumulate α-synuclein, and thus are showing PD specific pathological features, we undertook the present PhD work to investigate whether the enteric glia in PD become reactive by assessing the expression and phosphorylation levels of GFAP protein in colonic biopsies. In parallel we investigated whether changes in the intestinal epithelial barrier (IEB) function and/or morphology occur in PD by measuring the para- and transcellular permeabilities in colonic biopsies and by assessing the expression and localization of the two tight junctions protein ZO-1 and occludin. As compared to control subjects, patients with PD had significant higher enteric GFAP expression levels whereas the phosphorylation at serine 13 was significantly lower. The para- and transcellular permeabilities were not different between PD patients and controls. The expression of occludin, but not ZO-1, was significantly lower in colonic samples from PD patients as compared to controls and the cellular distribution of both proteins was altered in PD patients. Our findings provides evidence that the NGEU is altered in PD via accumulation of α- synuclein in enteric neurons, enteric glial reaction and IEB morphological impairments. This PhD work further reinforce the potential role of the gastrointestinal tract in the initiation and/or the progression of the disease
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Dikman, David. "Ambient Occlusion i Realtid." Thesis, University of Skövde, School of Humanities and Informatics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-1109.
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Ambient Occlusion är en teknik för ambient ljussättning i digitala tredimensionella scener. Sådana scener ljussätts vanligtvis med en konstant mängd ambient ljus på samtliga ytor oberoende av ytornas vinkel och position gentemot olika ljuskällor i scenen. Detta ger ett platt och kalt intryck och utan vidare ljussättningstekniker är det ytterst svårt att urskönja detaljer i scenen. Ambient Occlusion åthjälper detta genom att reducera mängden ambient ljus i vissa delar av scenen. Ambient ljus är en enkel approximation av det reflekterade diffusa ljuset som antas nå nästan överallt i scenen. Genom att sänka det ambienta ljuset på punkter i scenen med tät eller täckande geometri så ger Ambient Occlusion ett intryck av att det sekundära diffusa ljuset ej når dessa platser. Pappret undersöker en äldre variant av Ambient Occlusion där mängden ambient ljus beräknas statiskt för en scen och sparas i texturer. Vidare undersöks nyare metoder där mängden ambient ljus beräknas dynamiskt på den renderade scenen i Pixel Shaders. Det senare tillvägagångssättet kallas Image Based Ambient Occlusion eller Screen Space Ambient Occlusion. Detta nya tillvägagångssätt jämförs mot den traditionella angreppsvinkeln med förberäknade texturer. Teknikerna utvärderas och jämförs mot varandra i avseende på tids- och minneskomplexitet, enkelhet och visuellt resultat utöver specifika egenskaper för de enskilda teknikerna. Arbetets resultat beskrivs i slutet av rapporten. I resultatet presenteras hur shaderteknikerna pga sina brister inte är applicerbara i alla scener.
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Sténson, Carl. "Object Placement in AR without Occluding Artifacts in Reality." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211112.
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Placement of virtual objects in Augmented Reality is often done without regarding the artifacts in the physical environment. This thesis investigates how placement can be done with the artifacts included. It only considers placement of wall mounted objects. Through the development of two prototypes, using detected edges in RGB-images in combination with volumetric properties to identify the artifacts, arreas will be suggested for placement of virtual objects. The first prototype analyze each triangle in the model, which is an intensive and with low precision on the localization of the physical artifacts. The second prototype analyzed the detected RGB-edges in world space, which proved to detect the features with precise localization and a reduce calculation time. The second prototype manages this in a controlled setting. However, a more challenging environment would possibly pose other issues. In conclusion, placement in relation to volumetric and edge information from images in the environment is possible and could enhance the experience of being in a mixed reality, where physical and virtual objects coexist in the same world.Placering av virtuella objekt i Augumented Reality görs ofta utan att ta hänsyn till objekt i den fysiska miljön. Den här studien utreder hur placering kan göras med hänsyn till den fysiska miljön och dess objekt. Den behandlar enbart placering av objekt på vertikala ytor. För undersökningen utvecklas två prototyper som använder sig av kantigenkänning i foton samt en volymmetrisk representation av den fysiska miljön. I denna miljö föreslår prototyperna var placering av objekt kan ske. Den första prototypen analyserar varje triangel i den volymmetriska representationen av rummet, vilket visade sig vara krävande och med låg precision av lokaliseringen av objekt i miljön. Den andra prototypen analyserar de detekterade kanterna i fotona och projicerar dem till deras positioner i miljön. Vilket var något som visade sig hitta objekt i rummet med god precision samt snabbare än den första prototypen. Den andra prototypen lyckas med detta i en kontrollerad miljö. I en mer komplex och utmanande miljö kan problem uppstå. Placering av objekt i Augumented Reality med hänsyn till både en volymmetrisk och texturerad representation av en miljö kan uppnås. Placeringen kan då ske på ett mer naturligt sätt och därmed förstärka upplevelsen av att virtuella och verkliga objekt befinner sig i samma värld.
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Chambers, Destinee L. "Understanding Occlusion Inhibition: A Study of the Visual Processing of Superimposed Figures." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/open_access_dissertations/6/.
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Mak, Wai Ho. "Occlusion-resolving direct volume rendering /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CSED%202009%20MAK.
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BENEVIDES, LEONARDO DE PAULA BATISTA. "AMBIENT OCCLUSION FOR LINE RENDERING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26083@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
A interpretação tridimensional de conjuntos densos de linhas exige o uso de modelos de iluminação mais elaborados. A oclusão ambiente é uma técnica utilizada para simular, de forma realista e barata, a iluminação ambiente indireta. Este trabalho apresenta um novo algoritmo para renderização de linhas com oclusão de ambiente. O algoritmo proposto é baseado na voxelização da cena e no cálculo do volume ocupado do hemisfério associado a cada ponto do linha. Propõe-se uma adaptação no algoritmo de voxelização de cenas 3D formada por sólidos para o tratamento correto da cena formada por linhas. Assim, uma descrição volumétrica da geometria é criada em um buffer de textura. O hemisfério em torno de cada ponto visível é amostrado por diversos pontos, e para cada amostra se acessa um prisma, cujo volume ocupado é calculados a partir da voxelização. Ao acumular os resultados de cada amostra, estima-se a oclusão de ambiente causada pela geometria em cada ponto visível pelo observador. Esta estratégia mostra-se adequada, pois tem como resultado imagens com alta qualidade em tempo real para cenas com grande complexidade.
The three-dimensional understanding of dense line sets requires the use of more sophisticated lighting models. Ambient occlusion is a technique used to simulate realistically and efficiently, the indirect ambient lighting. This paper presents a new algorithm for rendering lines with ambient occlusion. The proposed algorithm is based on the voxelization of the scene and on the computation of occlusionin the hemisphere associated to each visible point. It is proposed an adaptation of the voxelization algorithm of 3D scenes made up of solids to the correct treatment of the scene formed by lines. Thus, a volumetric geometry description is created in a texture buffer. The hemisphere around every visible point is sampled by several points, and for each sample is generated a prism, which occluded volume is calculated from the voxelization. By accumulating the results of each sample, the estimated ambient occlusion caused by the geometry at each point visible to the observer is computed. This strategy proved to be appropriate, resulting in high-quality images in real time for complex scenes.
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Amram, Wilio. "L' occlusion en prothèse complète." Aix-Marseille, 1985. http://www.theses.fr/1985AIX21065.
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Sarkaar, Ajit Bhikamsingh. "Addressing Occlusion in Panoptic Segmentation." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101988.
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Visual recognition tasks have witnessed vast improvements in performance since the advent of deep learning. Despite the gains in performance, image understanding algorithms are still not completely robust to partial occlusion. In this work, we propose a novel object classification method based on compositional modeling and explore its effect in the context of the newly introduced panoptic segmentation task. The panoptic segmentation task combines both semantic and instance segmentation to perform labelling of the entire image. The novel classification method replaces the object detection pipeline in UPSNet, a Mask R-CNN based design for panoptic segmentation. We also discuss an issue with the segmentation mask prediction of Mask R-CNN that affects overlapping instances. We perform extensive experiments and showcase results on the complex COCO and Cityscapes datasets. The novel classification method shows promising results for object classification on occluded instances in complex scenes.24
Visual recognition tasks have witnessed vast improvements in performance since the advent of deep learning. Despite making significant improvements, algorithms for these tasks still do not perform well at recognizing partially visible objects in the scene. In this work, we propose a novel object classification method that uses compositional models to perform part based detection. The method first looks at individual parts of an object in the scene and then makes a decision about its identity. We test the proposed method in the context of the recently introduced panoptic segmentation task. The panoptic segmentation task combines both semantic and instance segmentation to perform labelling of the entire image. The novel classification method replaces the object detection module in UPSNet, a Mask R-CNN based algorithm for panoptic segmentation. We also discuss an issue with the segmentation mask prediction of Mask R-CNN that affects overlapping instances. After performing extensive experiments and evaluation, it can be seen that the novel classification method shows promising results for object classification on occluded instances in complex scenes.
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Domaratius, Uwe. "Distributed Occlusion Culling for Realtime Visualization." Master's thesis, Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700351.
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This thesis describes the development of a distributed occlusion culling solution for complex
generic scenes. Moving these calculations onto a second computer should decrease
the load on the actual rendering system and therefore allow higher framerates. This work
includes an introduction to parallel rendering systems and discussion of suitable culling algorithms.
Based on these parts, a client-server system for occlusion culling is developed.
The test results of a prototypical implementation form the last part of this thesis.
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Coleman, Christopher Ryan. "Fast self-shadowing using occluder textures." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4912.
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A real-time self-shadowing technique is described. State of the art shadowing techniques that utilize
modern hardware often require multiple rendering passes and introduce rendering artifacts. Combining
separate ideas from earlier techniques which project geometry onto a plane and project imagery onto an
object results in a new real-time technique for self-shadowing. This technique allows an artist to construct
occluder textures and assign them to shadow planes for a self-shadowed model. Utilizing a graphics
processing unit (GPU), a vertex program computes shadowing coordinates in real-time, while a fragment
program applies the shading and shadowing in a single rendering pass. The methodology used to create
shadow planes and write the vertex and fragment programs is given, as well as the relation to the previous
work. This work includes implementing this technique, applying it to a small set of test models, describing
the types of models for which the technique is well suited, as well as those for which it is not well suited,
and comparing the techniqueâÂÂs performance and image quality to other state of the art shadowing
techniques. This technique performs as well as other real-time techniques and can reduce rendering
artifacts in certain circumstances.
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Chaudhry, Naeem Ashfaq. "Automatic Facial Occlusion Detection and Removal." Thesis, Umeå universitet, Institutionen för datavetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-61835.
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In our daily life, we are faced with many occluded faces. The occlusion may be from different objects like sunglasses, mufflers, masks, scarves etc. Sometimes, this occlusion is used by the criminal persons to hide their identity from the surroundings. In this thesis, a technique is used to detect the facial occlusion automatically. After detecting the occluded areas, a method for image reconstruction called aPCA (asymmetrical Principal Component Analysis) is used to reconstruct the faces. The entire face is reconstructed using the non occluded area of the face. A database of images of different persons is organized which is used in the process of reconstruction of the occluded images. Experiments were performed to examine the effect of the granularity of the occlusion on the aPCA reconstruction process. The input mask image is divided into different parts, the occlusion for each part is marked and aPCA is applied to reconstruct the faces. This process of image reconstruction takes a lot of processing time so pre-defined eigenspaces are introduced that takes very less processing time with very less quality loss of the reconstructed faces.
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Daniels, Victoria. "Studies of occlusion and associated illusions." Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241130.
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LISOWSKI, KARIN SULAMITA LEAO. "MPLICIT OCCLUDER METHOD AND VISUALIZATION APPLICATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10086@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORNeste trabalho aplicamos o método de oclusão implícita para acelerar o tempo de cálculo e renderização de isosuperfícies em dados volumétricos regulares. Dado um campo escalar contínuo f sobre um domínio D (onde Dé convexo) e um isovalor w, a oclusão implícita explora a continuidadede f para determinar os limites de visibilidades sem a necessidade de calcular a isosuperfície explicitamente. Aplicamos esta técnica para obter também as silhuetas visíveis das isosuperfícies.
In this work we apply the Implicit Occluders method for optimizing the computation and rendering of isosurfaces in regular volumetric data. Given a continuous scalar field f over a domain D and an isovalue w, Implicit Occluders exploits the continuity of f to determine visibility bounds without the need for computing the isosurface explicitly. We apply this technique to obtain also the visible silhouettes of isosurfaces.
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Ray, Chaudhuri Shraman. "Reasoning about objects under full occlusion." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119721.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 41-43).
While state-of-the-art machine learning models can outperform humans on certain tasks, most of them generalize poorly across domains and cannot reason about complex scenes. In this paper, we attempt to resolve this shortcoming by incorporating a physics engine as a prior for scene understanding. We test our approach on two computer vision tasks -- pose estimation and object matching -- under full occlusion, and demonstrate superior performance over state-of-the-art methods. We also present a preliminary case study which demonstrates that our model is consistent with human behavior. Our work demonstrates a successful approach to a novel and challenging task, provides a general framework to infer latent factors of scene via physics simulation, and extends support for intuitive physics-based approaches for robust visual reasoning.
by Shraman Ray Chaudhuri.
M. Eng.
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Plassman, Brenda L. 1957. "INSPIRATORY MUSCLE RESPONSES TO OCCLUSION (EMG)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291244.
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Ramakrishnan, Sowmya. "Analysis of images under partial occlusion." Thesis, Kingston University, 2002. http://eprints.kingston.ac.uk/20702/.
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In order to recognise objects from images of scenes that typically involve overlapping and partial occlusion, traditional computer vision systems have relied on domain knowledge to achieve acceptable performance. However there is much useful structural information about the scene, for example the resolution of figure-ground ambiguity, which can be recovered or at least plausibly postulated in advance of applying domain knowledge. This thesis proposes a generic information theoretic approach to the recognition and attribution of such structure within an image. It reinterprets the grouping process as a model selection process with MDL (minimum description length) as its information criterion. Building on the Gestalt notion of whole-part relations, a computational theory for grouping is proposed with the central idea that the description length of a suitably structured whole entity is shorter than that of its individual parts. The theory is applied in particular to form structural interpretations of images under partial occlusion, prior to the application of domain knowledge. An MDL approach is used to show that increasingly economical structural models (groups) are selected to describe the image data while combining lower level primitives to form higher level structures. From initially fitted segments, progressive groups are formed leading to closed structures that are eventually classified as foreground or background. Results are observed which conform well with human interpretations of the same scenes.