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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.
1

Protein kinase C isoform antagonism controls occludin phosphorylation and tight junction assembly

Andreeva, Anna. January 2004 (has links)
Berlin, Freie University, Diss., 2004. / Dateiformat: zip, Dateien im PDF-Format.
2

Efeito da SuplementaÃÃo com Alanil-Glutamina nas AlteraÃÃes da Permeabilidade Intestinal em Ratos Treinados Submetidos a um ExercÃcio Prolongado e Exaustivo de NataÃÃo

Antonio Klingem Leite de Freitas 09 August 2013 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O 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 N 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).
3

Modulation der Expression der Tight Junctions in epithelialen Monolayern als Antwort auf exogene Faktoren anhand der Untersuchung zweier Proteine Occludin und ZO-1 / Modulation of expression of tight junctions on an epithelial model as reaction of exogenous factors on experiences on two proteins: occludin and zo-1

Gläser, Theresa Constanze Pilar [geb. Marbe] January 2010 (has links) (PDF)
Untersuchung des transepithelialen Widerstands, der Transkriptionsmenge und der fluoreszenzmikroskopischen Verteilung der Proteine Occludin und ZO-1 in Monolayern in Reaktion auf exogene Faktoren. / Trials of Occludin and ZO-1 in an epithelial model by measure the transepithelial resistance, the transcriptionlevel and the microskopic distibution.
4

Oxidative Stress Alters Blood-Brain Barrier Integrity

Lochhead, Jeffrey James January 2011 (has links)
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.
5

EFFECT OF PERIPHERAL INFLAMMATORY PAIN ON THE BLOOD-BRAIN BARRIER

Hau, Vincent Sinh January 2005 (has links)
Currently, there is a growing body of research characterizing the blood-brain barrier (BBB) under normal physiological conditions; however, little is known about BBB regulation under pathophysiological conditions, such as inflammatory pain. This dissertation elucidates peripheral inflammatory pain effects on the BBB both functionally in terms of permeability and structurally via tight junction (TJ) protein expression and regulation.Inflammation was produced by subcutaneous injection of formalin, lambda-carrageenan, or complete Freund's adjuvant (CFA) into the right hind paw of rats. In situ perfusion and Western blot analyses were performed to assess BBB integrity after inflammatory insult. In situ brain perfusion determined that peripheral inflammation significantly increased the uptake of a membrane impermeant marker, sucrose into the cerebral hemispheres in all inflammatory models. Subsequently, a 0-168h time course study of lambda-carrageenan-induced inflammatory pain elicited a biphasic increase in BBB permeability of sucrose with the first phase occurring from 1-6h and the second phase occuring at 48h. Lambda-carrageenan-induced inflammatory pain also increased brain uptake of a commonly used analgesic, codeine at the same time-points. This is the first known observation that peripheral inflammation results in greater analgesic drug uptake to the brain. This uptake also correlated with its antinociceptive profile over a 168h time course. This suggests the presence of inflammatory pain may be an important consideration in therapeutic drug dosing, potential adverse effects and/or neurotoxicity.Western blot analyses showed altered TJ protein expression during peripheral inflammation. Occludin significantly decreased in the lambda-carrageenan- and CFA-treated groups. ZO-1 expression was significantly increased in all pain models. Claudin-1 protein expression was present at the BBB and remained unchanged during inflammation. Actin expression was significantly increased in the lambda-carrageenan- and CFA-treated groups. Over a 72h time period with lambda-carrageenan-induced inflammatory pain, altered TJ protein expression of occludin and ZO-1 correlated with permeability changes in BBB function. This is the first report of peripheral inflammation inducing alterations in TJs and increasing permeability of the BBB. This dissertation demonstrates that changes in the structure of TJs leading to alterations in the BBB may have important clinical ramifications concerning central nervous system homeostasis and therapeutic drug delivery.
6

Untersuchungen zum Genexpressionsmechanismus der Glukokortikoidvermittelten Occludin-Induktion an der Blut-Hirn-Schranke / The glucocorticoid mediated occludin induction in the blood-brain-barrier

Harke, Nina Natascha January 2009 (has links) (PDF)
Die Blut-Hirn-Schranke wird hauptsächlich vom Endothel der Hirngefäße gebildet und stellt die wichtigste Barriere zwischen Blutkompartiment und Hirnparenchym dar. Hauptverantwortlich für die Barrierefunktion der Gehirnkapillaren sind die Tight Junctions, die den Interzellularspalt des Endothels verschließen und dadurch die parazelluläre Permeabilität hydrophiler Moleküle und Ionen regulieren und einen hohen elektrischen Widerstand aufbauen. Das 65 kDa Transmembranprotein Occludin ist ein zentrales Element der Tight Junctions: Eine Induktion von Occludin führt zur Erhöhung der Barriereeigenschaften, während eine Erniedrigung des Occludin-Gehaltes zu einer verstärkten Kapillardurchlässigkeit und potenziell zu einer Schädigung des Hirngewebes führt. Im klinischen Alltag werden bereits seit vierzig Jahren Kortikosteroide bei Erkrankungen mit geschädigter Blut-Hirn-Schranke erfolgreich eingesetzt. Auch experimentell konnte im hiesigen Labor durch die Arbeitsgruppe von Prof. Förster eine Transaktivierung von Occludin durch Glukokortikoide wie Dexamethason nachgewiesen werden. Die zugrunde liegenden regulatorischen Mechanismen der Occludintransaktivierung blieben weitgehend unbekannt, insbesondere die Frage, ob die Geninduktion über direkte Zielgentransaktivierung oder über eine Protein-Protein-Interaktion mit anderen Transkriptionsfaktoren erfolgt. Das Vorhandensein putativer Glukokortikoid-responsiver Elemente innerhalb des Occludin-Promoters war ebenso noch nicht bekannt. In dieser Arbeit konnte dargestellt werden, dass für die erhöhte Occludin-Expression in Endothelzellen von Hirngefäßen durch Glukokortikoide ein funktioneller Glukokortikoid-Rezeptor als Homodimer nötig war. In den Experimenten wurden die jeweiligen Transaktivierungsniveaus des Occludin-Promoters durch einen Luciferase-Promoter-Reporter-Assay verglichen. Es wurden zum einen der Wildtyp-Glukokortikoidrezeptor, zum anderen ein mutagenisierter Rezeptor eingesetzt, dem die entscheidende Dimerisierungseigenschaft fehlt. Ohne die Ausbildung eines Rezeptor-Homodimers kann die Bindung an die Promoter-DNA nicht erfolgen. Im Vergleich zeigte sich, dass nur der Wildtyp-Glukokortikoidrezeptor zu einer erhöhten Genexpression führte, der mutagenisierte Rezeptor zeigte keine Induktion. Zudem konnte im Rahmen dieser Arbeit eine Bindungsstelle des Glukokortikoidrezeptors auf dem Occludin-Promoter identifiziert werden. Die Identifizierung des Glukokortikoid-responsiven Elements erfolgte durch Untersuchung der Glukokortikoid-Responsivität verschiedener Abschnitte des Occludin-Promoters. Auf zwei dieser Abschnitte fanden sich Gensequenzen, die der etablierten kanonischen Konsensussequenz und verschiedenen in der Literatur beschriebenen degenerierten Elementen entsprachen. Im Promoter-Reporter-Assay zeigte sich nur im distalen Promoterabschnitt eine erhöhte Occludin-Expression nach Glukokortikoid-Gabe. Dieses distale Element aus zwei Halbelementen (5’-ACATGTnnnnACAAAT-3’) wurde durch Immunopräzipitationsassays weiter eingegrenzt. Eine Mutagenisierung der Basenabfolge mit anschließend ausbleibender Transaktivierung und Immunopräzipitation bestätigte die Funktionalität des Glukokortikoid-responsiven Elements. Zusammenfassend konnte in dieser Arbeit erstmals die direkte dimerisierungsabhängige Glukokortikoidrezeptor-vermittelte Induktion von Occludin nachgewiesen und ein neues degeneriertes Glukokortikoid-responsives Element identifiziert werden, das für die Transaktivierung des Occludingens essentiell ist. / The blood-brain-barrier mainly consists of endothelial cells and is the most important barrier between blood vessels and brain parenchyme. Occludin represents an important part of the tight junctions, which seal and protect the blood brain barrier against paracellular diffusion of solutes to the brain parenchyme and are therefore responsible for the high resistance and low permeability between cerebral capillary endothelial cells. Induction of occludin leads to increased barrier properties while a decreased occludin-level results in elevated permeability and potential impairment of the brain tissue. In former studies the positive influence of glucocorticoids on the barrier properties because of an induction of the occludin gene could be shown. This doctorial thesis showed that for an elevated occludin expression level in cerebral endothelial cells a functional glucocorticoid receptor as a homodimer is needed. This was proved comparing the transactivation levels of a wild-type glucocorticoid receptor and a mutagenised receptor lacking the ability of dimerization employing the Luciferase-Promoter-Reporter-Assay. Binding to the promoter-DNA is not possible without the formation of the receptor homodimer. Increased transactivation could only be seen using the wild-type receptor, the mutagenised receptor did not show any induction. In addition this thesis identified a glucocorticoid-receptor binding-site in the occludin promoter. This was performed analyzing the responsivity of different parts of the occludin promoter to glucocorticoid treatment. Two sequences could be found which were similar to the canonical consensus sequence and other established degenerated glucocorticoid response elements. Using the promoter-reporter-assay an elevated occludin expression could be detected after glucocorticoid treatment within the distal segment of the promoter. This distal element consisting of two half sites (5’-ACATGTnnnnACAAAT-3’) was confirmed using immunoprecipitation assays. After site directed mutagenesis of the putative glucocorticoid response element Luciferase promoter reporter assay and chromatin immunoprecipitation assays revealed that disruption of the candidate binding site abolished glucocorticoid-induced reporter gene expression and binding of the glucocorticoid receptor in response to dexamethasone treatment. The fact that glucocorticoid stimulation did not affect gene expression in the mutant vector verified that the glucocorticoid response element is functional and that hormone binding is not possible after alteration of the sequence.
7

Einfluss von Neisseria meningitidis auf Tight-Junctions in humanen mikrovaskulären Hirnendothelzellen (HBMEC) / Influence of Neisseria meningitidis on tight junction proteins of human brain microvascular endothelial cells (HBMEC)

Heinen, Florian January 2011 (has links) (PDF)
Neisseria meningitidis ist mit jahrlich etwa 700.000 Erkrankungsfallen weltweit und einer Mortalitat von circa 7% einer der häufigsten Ausloser der bakteriellen Hirnhautentzündung. Der entscheidende Schritt zur Auslosung einer Meningitis ist die Uberwindung der Blut-Hirn-Schranke. Diese im menschlichen Korper einmalig dichte Barriere wird maßgeblich durch Tight-Junctions spezialisierter Endothelzellen der Hirnkapillaren aufrecht erhalten. Ob N. Meningitidis diese Barriere auf einem parazellulären oder transzellulärem Weg uberwindet, ist nicht vollstandig geklart. In dieser Arbeit wurde der Einfluss von N. meningitidis auf die Tight-Junction Proteine Occludin und ZO-1 unter Nutzung des HBMEC Zellkulurmodelles untersucht. Neben einer verminderten Genexpression von Occludin zeigte sich dabei eine Abspaltung eines 50 kDa Fragmentes von Occludin. Gleichzeitig konnte eine Umverteilung von Occludin von den Zellgrenzen in das Zytoplasma beobachtet werden. ZO-1 hingegen wurde weder in seiner Exprimierung, noch in seiner intrazellularen Verteilung beeinflusst. Mittels eines in dieser Arbeit etablierten Assays zur Bestimmung der Permeabilitat eines HBMEC-Monolayer als vereinfachtes in-vitro Modell der Blut-Hirn-Schranke konnte bestatigt werden, dass durch die Beeinflussung von Tight-Junction Proteinen die parazellulare Permeabilitat steigt. In weiteren Analysen konnten diese Prozesse auf eine gesteigerte Aktivitat von Matrixmetalloproteinase 8 zurückgefuhrt werden. Die Ergebnisse dieser Arbeit zeigen einen neuen Mechanismus auf, durch den N. meningitidis im Stande ist, die-Hinr-Schranke auf einem parazellulärem Weg zu überwinden. / Neisseria meningitidis is a leading cause of bacterial meningitis with about 700.000 cases per year and a mortality of approximately 7%. A crucial step in the pathogenesis of meningococcal meningitis is the crossing of the blood-brain barrier (BBB). This barrier mainly consists of tight junctions of the microvascular endothelial cells. It remains unclear whether N. meningitidis passes the BBB by a paracellular or transcellular route. In this work the influence of N. meningitidis on the tight junction proteins occludin and ZO-1 was investigated by using the HBMEC cell-culture model. Using QRT-PCR a reduced expression of occludin was seen, western-blot analyses showed a cleavage of occludin into a fragment of 50 kDA. Immonulourescence further showed a complete dissociation of occludin from the cell membrane, whereas ZO-1 was not influenced. By establishing a permeability-assay an increased permeability of the HBMEC monolayer after infection with N. meningitidis was demonstrated. Further work showed, that these effects are dependent of an increased activity of matrix metalloproteinase-8. These results reveal a new mechanism that could enable N. meningitidis to cross the BBB by a paracellular route.
8

Hormonal regulation of the testicular Sertoli cell tight junction

McCabe, Mark James, markmccabe02@hotmail.com January 2008 (has links)
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.
9

Wound healing in a suction blister model:an experimental study with special reference to healing in patients with diabetes and patients with obstructive jaundice

Koivukangas, V. (Vesa) 23 November 2004 (has links)
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.
10

Regulation of Intestinal Epithelial Barrier and Immune Function by Activated T Cells

Le, Nga Thi Thanh 26 January 2021 (has links)
No description available.

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