Dissertations / Theses on the topic 'Epithelial permeability'
To see the other types of publications on this topic, follow the link: Epithelial permeability.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 44 dissertations / theses for your research on the topic 'Epithelial permeability.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Dennison, Patrick Winford. "Epithelial permeability in asthma." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/416625/.
Full textAbstract:
Our knowledge and understanding of asthma have evolved over time, leading to new and improved treatments for this disease. Despite existing treatments however, there remains to date a significant proportion of asthmatics who remain poorly controlled, with unmet needs. Most existing treatments are based on the Th2-driven inflammation model of asthma, however there is increasing recognition of the importance of the epithelium in asthma pathogenesis. It has been proposed that the asthmatic epithelium is chronically damaged and unable to repair, with increased permeability as a result. Existing treatments do not address the epithelial damage directly, however there are now available recombinant growth factors that have been shown to have beneficial effects on epithelial healing. Our hypothesis was that modification of the epithelium, in effect boosting its repair using recombinant human keratinocyte growth factor (rhKGF), would lead to improvement in clinical parameters. This was explored in several fashions. Firstly a randomised, double-blind, placebo-controlled clinical trial was performed using 20 poorly controlled, moderate asthmatics, with the active treatment group receiving parenteral rhKGF. Assessments before and after drug administration included objective, clinically relevant, measures of asthma such as airway hyperresponsiveness (AHR) measurements, spirometric measures, exhaled nitric oxide measurements and peak flow recording. Subjective, patient-centred assessments were also made using questionnaires to assess asthma control and quality of life, and bronchoscopy was performed to obtain samples to measure biological effects of the drug. KGF treatment resulted in a significantly greater improvement in the primary outcome of mannitol AHR, together with greater improvements in quality of life in the active treatment group compared to placebo. Other features (such as methacholine AHR, asthma control questionnaire scores, spirometric values, exhaled nitric oxide and peak flow variability) did not differ significantly between the groups, although this may be due to a greater than expected placebo response. Biological outcomes also did not differ significantly between the groups, although this may have been due to the sampling time-point used. Concurrently to the clinical trial above, in vitro experiments were performed on cell cultures of epithelial cells from asthmatic and healthy donors, to verify and further explore the effects of KGF on an asthmatic epithelium. Specifically mechanical wounds were inflicted on the cultures, with assessment of the repair process using wound imaging, measurement of trans-epithelial electrical resistance (TER) and permeability to FITC-labelled dextran, in the presence and absence of KGF. As a subset of these experiments, some cultures were exposed to mechanical compression using air pressure, as a mimic for bronchoconstriction, to see if KGF was effective in these circumstances. Results confirm a biological effect for KGF on wound repair in the asthmatic epithelium, which can also partially overcome the deleterious effect of compression on wound healing. An intrinsic difference in wound healing between asthmatic and healthy cohorts, as previously reported, was not apparent. Lastly the potential of nuclear medicine imaging, to assess epithelial permeability, was explored, for its potential use in future studies of asthma treatments addressing the epithelium directly. Unfortunately this was halted after a pilot study suggested potential methodological flaws – the results and conclusions from this pilot study are presented here, with suggestions for future studies in this area.
2
Anderson, Keith G. "Modulation and quantitation of epithelial paracellular permeability." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324937.
Full text
3
Collares, Buzato Carla Beatriz. "Modulation of paracellular permeability and intercellular junctions in cultured epithelia." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283019.
Full text
4
Shang, Valerie C. M. "The effects of endocannabinoids and phytocannabinoids on bronchial epithelial permeability." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/31264/.
Full textAbstract:
Injury to the bronchial epithelium in respiratory diseases such as asthma and COPD results in the loss of barrier function and an elevated sensitivity to environmental insults. An increased release of the endogenous cannabinoid, anandamide in response to inhalation of allergen in asthmatic patients has been reported. In contrast, previous clinical trial findings suggest anti-inflammatory and broncho-relaxant properties of the phytocannabinoid, ∆9-tetrahydrocannabinol (THC). The aim of this study was, therefore, to determine the effects of endocannabinoids and phytocannabinoids on bronchial epithelial cell permeability and to investigate the mechanisms involved. Calu-3 human bronchial epithelial cells were cultured at air-liquid interface to allow development of tight junctions. Changes in transepithelial electrical resistance (TEER), a reflection of epithelial permeability, were measured at various time points post-treatment. The endogenous cannabinoid anandamide produced a significant reduction in TEER, which was unaffected by cannabinoid receptor antagonists, but attenuated by URB597, an inhibitor of fatty acid amide hydrolase, and by a combination of cyclooxygenase and lipooxygenase blockade. Subsequent immunoblotting data revealed that the expression of tight junction proteins, occludin and ZO-1, were also reduced by anandamide. Inhibition of ERK activation by MEK1/2 inhibitors, PD98059 and U0126, prevented the anandamide-induced reduction in TEER and prevented the reduction in occludin expression. Thus, ERK activation is likely to mediate these effects by altering the expression of tight junction proteins. Treatment with THC prevented TNFα-induced decrease in TEER and increased in paracellular permeability. CB1 and CB2 receptor-like immunoreactivity was found in Calu-3 cells. Subsequent pharmacological blockade of either cannabinoid receptor inhibited the THC effect. In comparison, stimulation of both or either CB1 or CB2 receptors displayed similar effect to that of THC. Western immunoblotting also revealed reproducible decreases in occludin and ZO-1 expression in TNFα-treated cells, whereas cells pre-incubated with THC alone or in combination with TNFα did not alter expression levels. Phosphorylation of myosin-phosphatase target protein at threonine 696 residue by TNFα was attenuated in the presence of THC, indicating the involvement of RhoA/ROCK cascade. Selective stimulation of either cannabinoid receptor in TNFα-treated cells suggests THC-induced inhibitory effect on RhoA/ROCK signalling was mediated through CB2 receptor, and not CB1. In summary, these data suggest that the reduction in transepithelial resistance by anandamide, indicative of increased epithelial permeability, is caused by its metabolites rather than anandamide itself. Inhibition of anandamide degradation might provide a novel approach to treat airway inflammation. Conversely, THC reverses the reduction in transepithelial resistance caused by TNFα, through an effect at CB1 and CB2 receptors. Hence, THC, or perhaps other cannabinoid receptor ligands may have potential therapeutic roles in inflammation-induced changes in airway epithelial cell permeability, such as asthma and COPD.
5
Willemsen, Linette Eustachia Maria. "Intestinal barrier function: regulation of epithelial permeability and mucin expression." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/74526.
Full text
6
Rubelt, Miriam. "Enhancement of the intestinal epithelial permeability of peripherally acting opioid analgesics by chitosan." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16864.
Full textAbstract:
Die schmerzstillende Wirkung von Opiaten wird über Opioidrezeptoren im zentralen und peripheren Nervensystem vermittelt. Die Schmerzlinderung kann jedoch mit sehr starken Nebenwirkungen einhergehen, die das Patientenwohlbefinden beeinträchtigen. Dies legt die Bedeutung von neuen Opioidanalgetika nahe, die ihre schmerzstillende Wirkung ausschließlich über Opioidrezeptoren im PNS entfalten, ohne unerwünschte zentrale Nebenwirkungen zu induzieren. Die orale Gabe von Medikamenten minimiert Unannehmlichkeiten für den Patienten, jedoch müssen die Substanzen die intestinale Barriere passieren können, um in die Blutzirkulation eintreten zu können. Die intestinale Permeabilität von zwei peripher wirksamen Opiaten (AS006 und Loperamid) wurde in Ussing-Kammer Experimenten untersucht. Um die Darmepithelpermeabilität für beide Opiate zu erhöhen, wurde der Absorptionsverstärker Chitosan verwendet. Chitosan bewirkte nach 30 Minuten bei HT29/B6 und Caco-2 Zelllinien eine Abnahme des epithelialen Widerstands in vitro. Die Permeabilität für AS006 war bei beiden Zelllinien erhöht, für Loperamid nur bei HT29/B6, jedoch nicht bei Caco-2 Zellmonolayern. Verhaltensexperimente zur Messung des antinozizeptiven Effektes von oral appliziertem Loperamid auf Entzündungsschmerz wurden an Ratten durchgeführt. Die orale Gabe von Loperamid induzierte eine Dosis-abhängige antinozizeptive Wirkung in der entzündeten Hinterpfote. Bei oraler Gabe von Loperamid in Kombination mit Chitosan wurde keine signifikante Verstärkung des maximalen antinozizeptiven Effekts von Loperamid beobachtet. Zusammenfassend ist Chitosan ein geeigneter Absorptionsverstärker für intestinale Permeabilitätsstudien von peripher wirksamen Opioidanalgetika in vitro. Die in vitro Ergebnisse haben gezeigt, dass der Effekt von Chitosan auf Loperamid möglicherweise schwächer ist als auf AS006. Dementsprechend fiel die Wirkung des Absorptionsverstärkers auf Loperamid-induzierte Analgesie im Verhaltensversuch eher gering aus.Analgesic effects of opioids are mediated by opioid receptors that are widely distributed in the central and peripheral nervous systems (CNS and PNS, respectively). Although opioids are the most powerful analgesics, severe side effects restrict their use and affect patient convalescence. This suggests an advantage of new analgesic opioids which selectively bind to opioid receptors in the PNS. After oral administration however, peripherally restricted opioids first have to cross the intestinal epithelial barrier before absorption into the circulation and distribution to opioid receptors in peripheral tissues. Here, the transport across intestinal epithelia of two opioid ligands (AS006 and loperamide) that selectively activate peripheral opioid receptors without entering the CNS were investigated. To increase the intestinal passage of these drugs, the absorption enhancer chitosan was used. Chitosan significantly decreased the transepithelial resistance of HT29/B6 and Caco-2 cell monolayers after 30 min in vitro. The permeability values for AS006 increased from < 0.3 × 10-6 cm/s up to 10 × 10-6 cm/s in the presence of chitosan. In contrast, HT29/B6 monolayers showed moderate loperamide permeability in the presence of chitosan, and chitosan had no effect on the permeability of loperamide using Caco-2 monolayers. Oral administration of loperamide induced a dose-depended elevation of paw pressure thresholds in inflamed paws that lasted for 60 min. Oral administration of loperamide combined with chitosan slightly but nonsignificantly enhanced the antinociceptive effect of loperamide. In conclusion, chitosan is a suitable absorption enhancer for in vitro intestinal permeability studies. Future in vivo experiments might investigate different formulations and application schedules, and further address the effects of chitosan on the antinociceptive efficacy of hydrophilic opioids.
7
Yi, Sheng. "Synthetic peptides modulate epithelial junctions." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2344.
Full text
8
Elghadban, Salma. "Role of matriptase in the regulation of epithelial barrier permeability studied using MDCK cells." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/53377/.
Full textAbstract:
The typeNII transmembrane serine protease matriptase plays an important role in the integrity of epithelial barriers. However, the molecular mechanisms underlying the role of matriptase are unknown. To study these mechanisms, two variants of MadinNDarby canine kidney (MDCK) cells were used, together with the “calciumNswitch” model of epithelial function with measurements of transepithelial electrical resistance (TEER). Inhibitors of matriptase proteolytic activity delayed the restoration of TEER after calciumNswitch in MDCKNI, which develop high TEER and lack the “leaky” tight junction protein claudinN2, but not MDCKNII. This effect was confirmed in MDCKNI, established to stably express matriptase targeted shRNA. The influence of matriptase inhibition on MDCKNI was shown not to involve altered expression or assembly of relevant components of paracelluar junctions or cytoskeleton. This excluded a role for claudinN2 in the function of matriptase, which had previously been shown in human CacoN2 cells, and this was confirmed using MDCKNI cells stably overexpressing claudinN2. To investigate the claudinN2Nindependent function of matriptase, a candidate substrate approach was used. Proteolytic activation of proNHGF/cNMet, PARN2, ENaC, EGFR and prostasin by matriptase has effects on epithelial cell function, but none were found to have a role in matriptase restoration of TEER after calciumN switch in MDCKNI cells. As the direct proteolytic target of matriptase could not be identified, potential mediators were studied using arrays for phosphorylated signalling proteins and inflammatory cytokines. ILN1β and complement component C5 were identified as genes downregulated by matriptase inhibition, while ILN13 showed upregulation. This work has confirmed the key role of matriptase activity in regulating epithelial barrier integrity. The differential properties of MDCKNI and MDCKNII cells excluded a role for claudinN2. None of the known proteolytic targets of matriptase were involved, however, changes in cytokine gene expression may be a potential route for matriptase effects on epithelial barrier maintenance.
9
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.
Full text
10
Viljoen, Ianda. "The role of surfactant in, and a comparison of, the permeability of porcine and human epithelia to various chemical compounds." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1287.
Full text
11
McGilligan, Victoria. "The protective mechanisms of nicotine in relation to intestinal epithelial permeability and inflammation in ulcerative colitis." Thesis, University of Ulster, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445045.
Full text
12
Cruchley, Alan Timothy. "The relationship between epithelial permeability and the Langerhans cell population of normal human oral mucosa and skin." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281739.
Full text
13
Lagerquist, Hägglund Christine. "Affinity-, partition- and permeability properties of the human red blood cell membrane and biomembrane models, with emphasis on the GLUT1 glucose transporter /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3525.
Full text
14
Sonawane, Amit. "Evaluation of novel efflux transport inhibitor for the improvement of drug delivery through epithelial cell monolayer." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14424.
Full textAbstract:
Blood-brain barrier (BBB) is a unique membranous barrier, which segregates brain from the circulating blood. It works as a physical and metabolic barrier between the central nervous system (CNS) and periphery. In mammals, endothelial cells were shown to be of BBB and are characterized by the tight junctions along with efflux system which are responsible for the restriction of movement of molecules within the cells. Efflux system consists of multidrug resistance proteins such as P-glycoprotein (P-gp). P-gp removes substances out back from the brain to the blood before they reach to the brain. So the barrier is impermeable to many compounds such as amino acids, ions, small peptides and proteins, making it the most challenging factor for the development of new drugs for targeting CNS. Curcumin is a bioactive compound that has a number of health promoting benefits such as anti-inflammatory, anticancer, anti-oxidant agent; as well as a role in neurodegenerative diseases, but low oral bioavailability is the major limiting factor. Low water solubility and rapid metabolism are the two important factors responsible for poor bioavailability of curcumin. Galaxolide is a musk compound and previously known for the bioaccumulation of toxic components in the aquatic animals by interference with the activity of multidrug/multixenobiotic resistance efflux transporters (MDR/MXR). The bioavailability of curcumin can be enhanced when administered with galaxolide. This study was carried out to investigate the effect of galaxolide on the permeation of curcumin through the epithelial cell monolayers. MDCKII-MDR1 cell monolayer is used an in vitro blood-brain barrier model while Caco-2 monolayer is used as an in vitro intestinal model, which also expresses the P-glycoprotein. The curcumin and galaxolide were separately solubilised in the DMSO and used in combination to perform permeation study, to determine the effect of galaxolide on curcumin permeation through epithelial cell monolayers. The galaxolide shows an efflux protein inhibition activity and this activity was used to enhance permeation of curcumin through the Caco-2 monolayer. In summary, galaxolide is a novel permeation enhancer molecule, which can be used for the improvement of drug delivery of other bioactive compounds in future.
15
Rubelt, Miriam [Verfasser], Hans-Dieter [Akademischer Betreuer] Volk, Salah [Akademischer Betreuer] Amasheh, and Matthew [Akademischer Betreuer] Larkum. "Enhancement of the intestinal epithelial permeability of peripherally acting opioid analgesics by chitosan / Miriam Rubelt. Gutachter: Hans-Dieter Volk ; Salah Amasheh ; Matthew Larkum." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://d-nb.info/1045951439/34.
Full text
16
Chung, Charlotte Yuk-Yan. "Tight Junctions - The Link Between HIV-Associated Intestinal Barrier Dysfunction and Loss of Immune Homeostasis." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1417822947.
Full text
17
Nag, Subhra Sankar. "Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351.
Full text
18
Tretiach, Marina Louise. "Bovine Models of Human Retinal Disease: Effect of Perivascular Cells on Retinal Endothelial Cell Permeability." University of Sydney, 2005. http://hdl.handle.net/2123/1153.
Full textAbstract:
Doctor of Philosophy (Medicine)Background: Diabetic vascular complications affect both the macro- and microvasculature. Microvascular pathology in diabetes may be mediated by biochemical factors that precipitate cellular changes at both the gene and protein levels. In the diabetic retina, vascular pathology is found mainly in microvessels, including the retinal precapillary arterioles, capillaries and venules. Macular oedema secondary to breakdown of the inner blood-retinal barrier is the most common cause of vision impairment in diabetic retinopathy. Müller cells play a critical role in the trophic support of retinal neurons and blood vessels. In chronic diabetes, Müller cells are increasingly unable to maintain their supportive functions and may themselves undergo changes that exacerbate the retinal pathology. The consequences of early diabetic changes in retinal cells are primarily considered in this thesis. Aims: This thesis aims to investigate the effect of perivascular cells (Müller cells, RPE, pericytes) on retinal endothelial cell permeability using an established in vitro model. Methods: Immunohistochemistry, cell morphology and cell growth patterns were used to characterise primary bovine retinal cells (Müller cells, RPE, pericytes and endothelial cells). An in vitro model of the blood-retinal barrier was refined by coculturing retinal endothelial cells with perivascular cells (Müller cells or pericytes) on opposite sides of a permeable Transwell filter. The integrity of the barrier formed by endothelial cells was assessed by transendothelial electrical resistance (TEER) measurements. Functional characteristics of endothelial cells were compared with ultrastructural morphology to determine if different cell types have barrier-enhancing effects on endothelial cell cultures. Once the co-culture model was established, retinal endothelial cells and Müller cells were exposed to different environmental conditions (20% oxygen, normoxia; 1% oxygen, hypoxia) to examine the effect of perivascular cells on endothelial cell permeability under reduced oxygen conditions. Barrier integrity was assessed by TEER measurements and permeability was measured by passive diffusion of radiolabelled tracers from the luminal to the abluminal side of the endothelial cell barrier. A further study investigated the mechanism of laser therapy on re-establishment of retinal endothelial cell barrier integrity. Müller cells and RPE, that comprise the scar formed after laser photocoagulation, and control cells (Müller cells and pericytes, RPE cells and ECV304, an epithelial cell line) were grown in long-term culture and treated with blue-green argon laser. Lasered cells were placed underneath confluent retinal endothelial cells growing on a permeable filter, providing conditioned medium to the basal surface of endothelial cells. The effect of conditioned medium on endothelial cell permeability was determined, as above. Results: Co-cultures of retinal endothelial cells and Müller cells on opposite sides of a permeable filter showed that Müller cells can enhance the integrity of the endothelial cell barrier, most likely through soluble factors. Low basal resistances generated by endothelial cells from different retinal isolations may be the result of erratic growth characteristics (determined by ultrastructural studies) or the selection of vessel fragments without true âbarrier characteristicsâ in the isolation step. When Müller cells were co-cultured in close apposition to endothelial cells under normoxic conditions, the barrier integrity was enhanced and permeability was reduced. Under hypoxic conditions, Müller cells had a detrimental effect on the integrity of the endothelial cell barrier and permeability was increased in closely apposed cells. Conditioned medium from long-term cultured Müller cells and RPE that typically comprise the scar formed after lasering, enhanced TEER and reduced permeability of cultured endothelial cells. Conclusions: These studies confirm that bovine tissues can be used as a suitable model to investigate the role of perivascular cells on the permeability of retinal endothelial cells. The dual effect of Müller cells on the retinal endothelial cell barrier under different environmental conditions, underscores the critical role of Müller cells in regulating the blood-retinal barrier in health and disease. These studies also raise the possibility that soluble factor(s) secreted by Müller cells and RPE subsequent to laser treatment reduce the permeability of retinal vascular endothelium. Future studies to identify these factor(s) may have implications for the clinical treatment of macular oedema secondary to diseases including diabetic retinopathy.
19
Dasdelen, Süha [Verfasser], and Stephan [Akademischer Betreuer] Böhm. "Einfluss des PAR-2 auf die epitheliale Permeabilität und Ionensekretion im Gastrointestinaltrakt / Süha Dasdelen. Betreuer: Stephan Böhm." Marburg : Philipps-Universität Marburg, 2012. http://d-nb.info/1029819351/34.
Full text
20
Salmon, Damien. "Usage biopharmaceutique in vitro combiné des hydrogels thermoréversibles et d’une cellule de diffusion innovante." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1056/document.
Full textAbstract:
La biopharmacie s'intéresse au devenir du médicament au contact d'un épithélium. Cela conditionne la biodisponibilité du principe actif, rendant les études biopharmaceutiques indispensables au développement des médicaments. L'obtention de données biopharmaceutiques in vitro passe par l'utilisation de cellules de diffusion. La variabilité des résultats expérimentaux obtenus nous a conduits à développer un nouveau dispositif nommé VitroPharma, destiné à optimiser l'étude de la perméabilité épithéliale. Son originalité réside dans la possibilité d'employer les milieux récepteurs semi-solides en substitution des milieux liquides habituels.Ce travail propose une exploration des capacités de VitroPharma en vue de sa validation. Le dispositif est testé en modalités de dose (i) finie et (ii) infinie, sur (i) peau porcine et (ii) membrane artificielle de silicone, respectivement. Des milieux récepteurs (i) liquide, (ii) semi-solide (hydrogel d'agarose) et (iii) thermogélifiant (hydrogel de poloxamer) sont évalués. La caféine et la testostérone sont utilisées comme composés modèles. Les résultats sont comparés à une méthode de référence.De plus, deux problématiques expérimentales peu étudiées dans la littérature sont évaluées : (i) la formation de bulles à l'interface milieu récepteur-membrane et (ii) l'altération de l'hydratation des membranes biologiques en cours d'essai. Il ressort que l'utilisation de VitroPharma combinée à un milieu récepteur thermogélifiant permet (i) de limiter la formation de bulles et (ii) de contrôler le contenu en eau des explants cutanés.Ainsi le dispositif VitroPharma apparait comme adapté à la tenue d'essais de perméabilité épithéliale, apportant notamment, (i) une manipulation facilitée, (ii) une optimisation des conditions d'essai et (iii) l'obtention de résultats cinétiques de pénétration. Des exemples de développements cliniques mettant à profit les performances de VitroPharma sont présentés en conclusionBiopharmacy studies the outcomes of contact between a medicine and its administration site epithelium, thus determining active compound bioavailability. Hence, biopharmaceutical studies are paramount to drug development processes. Biopharmaceutical data are obtained in vitro using experimental devices (i.e., diffusion cells) but show high variability. To overcome this limitation we development a new experimental device, called VitroPharma, meant to optimize the study of epithelial permeability. Distinctiveness of this innovating diffusion cell is due to substitution of classical liquid receptor medium with semi-solid medium.In this work, validation studies of VitroPharma are detailed including (i) finite and (ii) infinite dosing protocols using (i) biological membrane (i.e., pig ear skin) and (ii) artificial silicone membrane, respectively. Three different types of receptor medium are employed: (i) liquid medium, (ii) semi-solid medium (i.e., 2% agarose hydrogel) and (iii) thermogelifying medium (i.e., 20% poloxamer 407 hydrogel). Caffeine and testosterone are used as model compounds. Permeability results are displayed and compared to that obtained using reference Franz static diffusion cell.Furthermore, two experimental pitfalls often mentioned but scarcely studied in literature are evaluated, that is (i) bubble formation at the membrane-receptor medium interface and (ii) biological membrane hydration modification over assay time. VitroPharma combined to thermogelifying receptor medium was found efficient (i) in reducing bubble formation and (ii) enabling control of biological membrane water content.Therefore, VitroPharma appears adapted to the in vitro study of epithelial permeability, enabling (i) easy handling, (ii) optimized experimental parameters and (iii) dual penetration and permeation determination. To conclude this work, examples of clinical outcomes that could advantageously use VitroPharma are presented
21
Carlowitz, Corinna von [Verfasser]. "Die Wirkung von Adrenomedullin auf die epitheliale Permeabilität des Darms in vivo und in vitro / Corinna von Carlowitz." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2018. http://d-nb.info/1153769298/34.
Full text
22
Juel, Ingebjørg S. "Intestinal injury and recovery after ishemia - An experimental study on restitution of the surface epithelium, intestinal permeability, and release of biomarkers from the mucosa." Doctoral thesis, Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1817.
Full text
23
Jaussaud, Alain. "Etude de la perméabilité épithéliale cornéenne par fluorophotométrie, chez des patients glaucomateux, avant et après traitement par timolol." Montpellier 1, 1996. http://www.theses.fr/1996MON11039.
Full text
24
Monteiro, Talita Ferreira. "Desenvolvimento de novo método ex vivo para estudo da permeabilidade de fármacos utilizando epitélio intestinal de rã-touro (Rana catesbeiana)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-28032013-121959/.
Full textAbstract:
Este trabalho teve como objetivo propor novo método para estudar a permeabilidade de fármacos, utilizando epitélio intestinal de rã-touro (Rana catesbeiana) em método ex vivo, empregando células de Franz. Por utilizar epitélio intestinal, um material de descarte proveniente de um animal utilizado como alimento humano, pode ser considerado um método alternativo, pois não implica no sacrifício de animais. A quantidade de fármaco permeada foi determinada por método de eletroforese capilar com detecção ultravioleta e validado para os antivirais lamivudina, zidovudina e aciclovir, na presença de metoprolol e floridizina. O fármaco escolhido como modelo nos ensaios de permeabilidade foi a lamivudina. Para estabelecimento do protocolo experimental dos estudos de permeabilidade, foi proposta uma análise de variância three-way para verificar a influência na permeabilidade dos fármacos, das seguintes variáveis: secção intestinal, pH da solução de Ringer e temperatura. Foram determinados a quantidade total de fármaco permeado (Qt), o coeficiente de permeabilidade aparente (Papp) e a constante de absorção de primeira ordem (ka). A partir da análise do planejamento experimental, os efeitos das variáveis não foram significativos, exceto para a secção intestinal. Os resultados de coeficiente de permeabilidade aparente (Papp) obtidos foram de 0,09 x 10-4 cm/s para lamivudina e de 0,22 x 10-4 cm/s para o metoprolol. O valor de Papp obtido de para o metoprolol é próximo dos valores encontrados na literatura para outras técnicas. Para a lamivudina, entretanto, a diferença encontrada em comparação às células Caco-2 pode ser devida às diferentes técnicas empregadas.This work aimed to propose a new method for studying drug permeability using frog intestinal epithelium (Rana catesbeiana) in ex vivo method, using Franz cells. By using intestinal epithelium, a disposal material from an animal used as human food, can be considered an alternative method, because it doesn\'t involve the sacrifice of animals. The amount of permeated drug was determined by capillary electrophoresis method with UV detection and validated for antiviral drugs lamivudine, zidovudine and acyclovir in the presence of metoprolol and floridizina. The drug chosen as a model in permeability studies was lamivudine. To establish the experimental protocol for the permeability studies, a three-way analysis of variance was proposed to check the influence of intestinal section, pH of Ringer\'s solution and the temperature on the permeability. Total amount of drug permeated (Qt), apparent permeability coefficient (Papp) and first-order constant absorption (ka) were determined. By the analysis of experimental design, the effects of the variables were not significant, except for intestinal section. The results of apparent permeability coefficient (Papp) obtained were 0.09 x 10-4 cm/s for lamivudine and 0.22 x 10-4 cm/s for metoprolol. The value of Papp obtained for metoprolol is quite close to the values found in literature for other methods. For lamivudine, however, the difference found in comparison to Caco-2 cells may be due to different techniques.
25
Salim, Sa'ad Yislam. "Mucosal dendritic cells in inflammatory bowel disease." Doctoral thesis, Linköpings universitet, Kirurgi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52234.
Full textAbstract:
Crohn's disease, a chronic inflammation of the bowel, is a multi-factorial condition where uncontrolled immune responses to luminal bacteria occur in genetically predisposed individuals. The first observable clinical signs are small ulcers that form at a specialised form of epithelium, follicle-associated epithelium (FAB). The FAB covers immune inductive sites, Peyer's patches, which function primarily as sensory areas that sample the externaI gut environment. Dendritic cells are one of the key cells that are involved in sensing luminal contents and orchestrating the gut immune system. The main aim of this thesis was to determine whether the barrier of the FAB is breached in Crohn's disease and if dysfunctional immune regulators, namely dendritic cells, playaroIe in initiating and/or maintaining the chronic intestinal inflammation. Using biopsies and surgical specimens, we were able to show that in Crohn's disease, there was an increased transmucosaI transport of Escherichia coli compared to specimens from ulcerative colitis and non-inflammatory bowel disease (IBD) controIs. Dendritic cells internalised a higher percentage of bacteria that had translocated across the FAB in the Crohn's samples. Furthermore, significantly higher concentrations of TNF-u was released upon bacterial stimulation by tissues from patients with Crohn's disease than in controIs. We went on to characterise the dendritic cells present in the Peyer's patches of patients with Crohn's disease. We found an accumulation of both immature and mature dendritic cells beneath the FAB, in the sub-epithelial dome (SED). Normally, mature dendritic cells migrate towards T cell-rich areas. However, we observed mature dendritic cells accumulating in the SED because they lacked the CCR7 migratory receptor. Furthermore, they were more prone to take-up bacteria, and produced TNF-α. To study the function of mucosal dendritic cells, we performed isolation experiments and mixed Iymphocyte reactions. Dendritic cells from both the ileum and blood of patients with active Crohn's had reduced capacity for inducing T cell proliferation than non-IBD controIs. Blood dendritic cells of patients in remission had normalised function that was similar to dendritic cells from healthy controls. The SAMPl/YitFc mice, considered an appropriate murine model for Crohn's disease, had an inherent permeability defect that increased with the chronicity of intestinaI inflammation. However unlike in human Crohn's disease, dendritic cells did not seem to playaroIe in murine ileitis. This thesis highlights the accumulation of the actively surveying dendritic cells that are prone to bacterial internalisation, and points to their possible different functional roles in active versus in-active disease; thereby confirming dendritic cells as one ofthe key components in the pathogenesis ofCrohn's disease.
26
Keita, Åsa. "Barrier function of the Follicle-Associated Epithelium in Stress and Crohn's disease." Doctoral thesis, Linköpings universitet, Kirurgi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9271.
Full textAbstract:
Crohns sjukdom är en kronisk inflammatorisk tarmsjukdom av okänd orsak. Det tidigaste tecknet på Crohns sjukdom är mikroskopiska sår i det s.k. follikelassocierade epitelet (FAE) som täcker ansamlingar av immunceller i tarmen. FAE är specialiserat för att fånga innehåll från tarmen och transportera det till underliggande immunvävnad. Denna funktion är viktig för att inducera skyddande immunsvar, men den utgör också en ingångsväg för sjukdomsalstrande bakterier. Crohns sjukdom är associerat med ett kraftigt ökat immunsvar mot bakterier, och sjukdomsförloppet kan ändras av stress. Det övergripande syftet med avhandlingen var att studera effekterna av stress på FAE samt att undersöka rollen av FAE vid utvecklingen av tarminflammation, särskilt vid Crohns sjukdom. Inledningsvis studerades effekterna av psykologisk stress på FAE. Stressade råttor uppvisade ökad genomsläpplighet av bakterier efter stress, och passagen var högre i FAE än i vanligt epitel. Efterföljande experiment visade att stressförändringarna i slemhinnan regleras via kortikotropinfrisättande hormon och mastceller. Vidare visade det sig att vasoaktiv intestinal peptid kunde efterlikna stressens effekter på genomsläppligheten, och att detta kunde förhindras genom att blockera mastcellerna. Studier av tunntarmsslemhinna från patienter med icke-inflammatorisk tarmsjukdom och friska kontroller visade en högre passage av bakterier i FAE än i vanligt epitel. Hos patienter med Crohns sjukdom var bakteriepassagen genom FAE betydligt ökad jämfört med kontroller. Resultaten från detta avhandlingsarbete visar att stress kan förändra upptaget av bakterier från tarmen via FAE, med mekanismer som innefattar kortikotropinfrisättande hormon och mastceller. Detta har gett nya kunskaper kring regleringen av slemhinnebarriären. Vidare presenterar denna avhandling nya insikter i sjukdomsuppkomsten vid Crohns sjukdom genom att påvisa en tidigare okänd defekt i barriärfunktionen i FAE.The earliest observable signs of Crohn’s disease are microscopic erosions in the follicle-associated epithelium (FAE) covering the Peyer’s patches. The FAE, which contains M cells, is specialised in sampling of luminal content and delivery to underlying immune cells. This sampling is crucial for induction of protective immune responses, but it also provides a route of entry for microorganisms into the mucosa. Crohn’s disease is associated with an increased immune response to bacteria, and the disease course can be altered by stress. The overall aim of this thesis was to study the effects of stress on the FAE and elucidate the role of FAE in the development of intestinal inflammation, specifically Crohn’s disease. Initially, rats were submitted to acute and chronic water avoidance stress to study the effects of psychological stress on the FAE. Stressed rats showed enhanced antigen and bacterial passage, and the passage was higher in FAE than in regular villus epithelium (VE). Further, stress gave rise to ultrastructural changes. Subsequent experiments revealed the stress-induced increase in permeability to be regulated by corticotropin-releasing hormone and mast cells. Furthermore, vasoactive intestinal peptide (VIP) mimicked the stress effects on permeability, and the VIP effects were inhibited by a mast cell stabiliser. Human studies of ileal mucosa from patients with non-inflammatory disease and healthy controls showed a higher antigen and bacterial passage in FAE than in VE. In patients with Crohn’s disease, the bacterial passage across the FAE was significantly increased compared to non-inflammatory and inflammatory controls (ulcerative colitis). Furthermore, there was an enhanced uptake of bacteria into dendritic cells, and augmented TNF-α release in Crohn’s disease mucosa. Taken together this thesis shows that stress can modulate the uptake of luminal antigens and bacteria via the FAE, through mechanisms involving CRH and mast cells. It further shows that human ileal FAE is functionally distinct from VE, and that Crohn’s disease patients exhibit enhanced FAE permeability compared to inflammatory and non-inflammatory controls. This thesis presents novel insights into regulation of the FAE barrier, as well as into the pathophysiology of Crohn’s disease by demonstrating a previously unrecognised defect of the FAE barrier function in ileal Crohn’s disease.
27
Pietz, Grzegorz. "Innate immunity of human intestinal epithelium in childhood celiac disease : influences from celiac disease associated bacteria and dietary oats." Doctoral thesis, Umeå universitet, Institutionen för molekylärbiologi (Medicinska fakulteten), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-140691.
Full textAbstract:
Background & Aims: Celiac disease (CD) is a chronic inflammatory small-bowel enteropathy caused by permanent intolerance to gliadin in wheat gluten, and related proteins in ray and barley. It is disputed whether CD patients tolerate oats. The only treatment of CD is lifelong gluten-free diet (GFD). Only individuals that carry the HLA-DQ2 and/or DQ8 alleles, and eat gluten can develop CD. Dysbiosis in the gut microbiota is a suggested risk factor for CD. T cells in small intestinal mucosa, including intraepithelial lymphocytes (IELs), are known to be important in the pathogenesis of CD. In contrast, the role of intestinal epithelial cells (IECs) is poorly understood. In this thesis we investigated the role of IECs in the immune pathology of CD from duodenal mucosa of children with CD, clinical controls and treated CD. We also investigated the role of CD associated bacteria and oats supplemented GFD on the mucosal immune system. Results: A new CD-associated bacterium, Prevotella jejuni, was isolated and characterized. It is a saccharolytic and proteolytic anaerobe. More than 25 defense-related genes, including IRF1, SPINK4, ITLN1, OAS2, CIITA, HLA-DMB, HLA-DOB, PSMB9, TAP1, BTN3A1, and CX3CL1, were upregulated in IECs in active CD. In two in vitro models for intestinal epithelium, small intestine enteroids and T84 polarized tight monolayers, we showed that 70% of these genes were upregulated by interferon (IFN)-γ via the IRF1 pathway. IRF1 was also upregulated by the CD-associated bacteria P. jejuni and Actinomyces gravenitzii. IECs expressed the NLRP6/8 inflammasome yielding CASP1 and biologically active interleukin (IL)-18, which induces IFN-γ in IELs. P. jejuni bound the intestinal epithelial cell lines T84, Caco2, HT29, and INT407, while Lachnoanaerobaculum umeaense preferentially bound Caco2. P. jejuni caused decreased transepithelial resistance over tight monolayers, while L. umeaense caused an increase. P. jejuni upregulated mRNAs for the detoxification molecules CYP1A1, CYP1A2, CYP1B1, and TIPARP, the chemokines CX3CL1, CXCL1, and CXCL10, the sialyltranserase ST3GAL4, and the inflammation promoting protein S100A3 in tight monolayers. L. umeaense upregulated the chemokines CCL20 and CXCL10, and down-regulated TLR2. In a randomized, double-blinded intervention trial comparing two study-groups, standard GFD and oat-containing GFD, we found that mRNAs for several immune effector molecules and tight junction proteins were only reduced in patients receiving GFD, but not in a substantial fraction of patients on GFD with oats. The down-regulatory cytokines IL-10 and TGF-β1, the cytotoxicity-activating NK-receptors NKG2C and NKG2E, and the tight junction protein claudin-4 remained elevated in the study group on GFD with oats. Conclusions: IECs are far from inactive in CD. A key factor in the epithelial reaction in CD appears to be over-expression of IRF1 in IECs. Dual activation of IRF1 and IRF1-regulated genes, both directly by P. jejuni and indirectly by IFN-γ via the IL-18-inflammasome, would drastically enhance the inflammatory response and lead to the pathological situation seen in active CD. P. jejuni harms the intestinal epithelium, i.e., it is a likely risk factor for CD, while L. umeaense strengthen barrier function and local immunity, possibly acting as a protective. A fraction of CD patients should avoid oats in the diet.Doctoral thesis
28
Daniel, Emeline. "Cytodiérèse des cellules épithetiales et maintien de l'intégrité du tissu chez Drosophila melanogaster." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B049/document.
Full textAbstract:
Les cellules épithéliales forment un tissu de cellules étroitement juxtaposées qui assure une barrière physique et chimique entre les compartiments internes et externes du corps. L’intégrité de ces tissus est donc essentielle. Au cours du développement et de la vie adulte, le tissu doit grandir ou se régénérer, ce qui implique de nombreuses divisions cellulaires. La dernière étape de la division, la cytodiérèse, met en jeu la formation d’un anneau contractile qui, en se fermant, va séparer les cellules sœurs. Une fois complètement fermé, il donne naissance au midbody, juste sous le niveau des jonctions adhérentes, au sein des jonctions septées, chez la drosophile. L’ultime étape, l’abscission, permet la séparation physique définitive et l’isolation cytoplasmique des cellules sœurs. Si de nombreuses études ont décrit ces processus dans les cellules isolées, peu de choses sont connues quant à la cytodiérèse des cellules épithéliales. Ce travail de thèse a permis de mettre en évidence que malgré le recrutement de tous les effecteurs et régulateurs de l’abscission, celle-ci est retardée dans les cellules épithéliales. Des expériences de photo-conversion de KAEDE ont montré que l’abscission est liée à l’entrée en mitose des cellules épithéliales. La question de l’intégrité du tissu et notamment de la barrière de perméabilité a ensuite été investigué. Nous avons montré que les cellules voisines formaient des protrusions de membrane restant connectées au midbody tout au long de sa lente migration vers le pôle basal des cellules. Les expériences de FRAP menées sur les jonctions bicellulaires et tri-cellulaires des jonctions septées ont permis de montrer que celles-ci se formaient juste sous les jonctions adhérentes et toujours au-dessus du midbody, participant ainsi à la migration de ce dernier vers le pôle basal. Les contacts maintenus avec les voisines ainsi que l’assemblage polarisé des jonctions septées participent au maintien de l’intégrité du tissu au cours des divisions de cellules épithélialesEpithelial cells are closely juxtaposed to form a tissue playing a physical and chemical barrier between external and internal body compartments. Thus, tissue integrity is essential. During development and adult life, epithelia has to growth and regenerate meaning a lot of divisions. At the end of cell division, cytokinesis occurs, implying the formation of a contractile ring which contracts to separate daughter cells. In Drosophila, once totally closed, the contractile ring gives rise to the midbody, just below adherens junctions, in the septate junctions layer. Last step of cytokinesis, abscission, permits the final cut and the cytoplasmic isolation of daughter cells. If cytokinesis is well described in isolated cells, little is known about epithelial cells cytokinesis. This work shows that whereas all abscission regulators and effectors are recruited, abscission is delayed in epithelial cells. KAEDE photo-conversion assays show that abscission is linked to epithelial cells mitosis entry. Then we investigate how permeability barrier is maintained during cell division. We show that neighboring cells present finger-like protrusions contacting the midbody all along the midbody is moving basally across septate junctions. FRAP experiments on bicellular and tricellular septate junctions show that they form just below adherens junctions and always above the midbody, leading to its basal migration. Contacts maintained with neighbors and polarized assembly of septate junctions participate to the maintenance of tissue integrity throughout epithelial cells divisions
29
Souza, Paula Cristina Torres de. "Padronização de novo método ex vivo para avaliação da permeabilidade intestinal de fármacos utilizando epitélio intestinal de rã-touro (Rana catesbeiana): comparação com células Caco-2." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-28082014-103309/.
Full textAbstract:
Métodos in vitro utilizando epitélio intestinal animal são importantes ferramentas para avaliar a permeabilidade de fármacos, propriedade que é um importante parâmetro de biodiosponibilidade. Considerando que o maior objetivo na indústria farmacêutica é desenvolver novos fármacos com boa biodisponibilidade oral, o projeto teve como objetivo padronizar o modelo de permeação com membrana de intestino de rã (Rana catesbeiana) em células de Franz, comparando seus resultados com ensaios de células Caco-2. Os fármacos modelo utilizados foram os antivirais zidovudina e aciclovir. A quantidade de fármaco permeado foi determinada por método de eletroforese capilar para o método com intestino de rã touro e por HPLC-UV para os ensaios com células Caco-2. O parâmetro de permeação foi o coeficiente de permeabilidade aparente (Papp) dos fármacos para ambos modelos experimentais. Para estabelecimento do protocolo experimental dos estudos de permeabilidade intestinal de rã, foi proposto um projeto fracionado 24-1 com 4 ensaios adicionais usando o software Minitab, e as variáveis foram: secção intestinal, pH da solução de Ringer e temperatura. A análise do planejamento experimental feita pela estimativa dos parâmetros da regressão obtidos através dos resultados do modelo fatorial possibilitou a determinação dos coeficientes da equação matemática que definiu a influência das variáveis sobre o coeficiente de permeabilidade aparente dos fármacos. Os efeitos das variáveis pH e temperatura interpretados conjuntamente apresentaram interferência leve, porém as variáveis fármaco e secção intestinal interpretados juntos tiveram interferência importante, mostrando maior permeação dos fármacos através da secção inicial do intestino da rã. Os resultados de Papp foram: para o metoprolol, pelo método das células Caco-2 foi de 28 x 10-6 cm/s, valor que está de acordo com demais dados de células Caco-2 na literatura e o valor obtido com células de Franz que mais se adequada a estes resultados e demais disponíveis provenientes de outras técnicas na literatura, foi de 28,1 x 10-6 cm/s, em uma das condições do planejamento estatístico utilizando segmento final da membrana epitelial da rã. No caso do aciclovir, o resultado de Papp de 0,48 x 10-6 cm/s também obtido em uma das condições envolvendo segmento intestinal final da rã foi exatamente igual a o valor 0,48 x 10 - 6 cm/s, encontrado com células Caco-2 no presente estudo e estão de acordo com outros valores disponíveis na literatura por Trapani e colaboradores, 2004 e também com células Caco-2. Para zidovudina o valor de Papp obtido em uma das condições utilizando segmento intestinal inicial da rã, de 13 x 10-6 cm/s, foi a que mais se assemelhou ao obtido pela técnica de células Caco-2, 13,6 x 10-6 cm/s, e também está de acordo com demais dados da literatura.There are lots of different in vitro technics in the literature using animal intestinal epithelium to estimate permeability of drugs, property that is an important parameter of bioavailabity. Considering that the main objective of Pharmaceutical Companies is the development of new drugs with good oral bioavailabity, the aim of this work was to standardize the permeability of antivirals using in vitro/ex vivo method of intestinal epithelium of Rana catesbeiana in Franz cells and compare these results to those obtained from studies using Caco-2 cells. Zidovudine and Acyclovir were selected as model drugs. The amount of drug permeated will be determined by the method of capillary electrophoresis for assays using Rana Catesbeiana and HPLC-UV for studies with Caco-2 cells. The permeation parameter determined was the apparent permeability coefficient (Papp) of drugs for both experimental models. To establish the experimental protocol to studies of intestinal permeability of frog, it was proposed a fractional 24-1 design with 4 additional tests using Minitab software and the variables were: intestinal section, pH of Ringer solution and temperature. The analysis of the experimental design made by the estimate of the regression parameters obtained from the factorial model results allowed the determination of the coefficients of the mathematical equation that defines the influence of the variables on the apparent permeability coefficient of acyclovir and zidovudine. The effects of pH and temperature interpreted jointly presented a slight interference, but the variables drug and intes tinal section interpreted together had major interference, showing greater permeation of drugs through the initial section of the intestine of the frog . The results of Papp were: for metoprolol, with the method of Caco-2 cells was 28 x 10-6 cm/s, a value which is consistent with other data of Caco-2 cells provided in the literature and the condition obtained with Franz cells that are most suitable for these and other results obtained from other techniques available in the literature, was 28.1 x 10-6 cm/s, provided with the final intestinal segment using frog epithelial membrane. In the case of acyclovir, the result of Papp of 0.48 x 10-6 cm/s obtained in one condition with final frog intestinal segment was exactly equal to the value of 0.48 x 10-6 cm/s, found with Caco-2 cells in the present study and are in agreement with other values available in the literature for Trapani and colegues, 2004 and also with Caco-2 cells. The Papp value for zidovudine obtained with the initial gut segment of frog, 13 x 10-6 cm /s was which more resembled that obtained by the technique of Caco-2 cells, 13.6 x 10-6 cm/s and is also consistent with other literature data.
30
Matysiak-Budnik, Tamara. "Helicobacter pylori et modifications de la perméabilité épithéliale gastrique." Bordeaux 2, 2000. http://www.theses.fr/2000BOR28767.
Full text
31
Dossou-Yovo, Flore. "Modification de la biodisponibilité orale des médicaments : interactions « Herb-Drugs » « Drugs- Drugs»." Thesis, Paris, CNAM, 2014. http://www.theses.fr/2014CNAM0936/document.
Full textAbstract:
L’administration par voie orale des médicaments reste encore de nos jours la voie royale de la prise des médicaments car moins onéreuse et plus adaptée au confort du patient. Mais cette voie reste toujours inaccessible pour certains médicaments comme les médicaments biologiques et les bio similaires voir certains anticancéreux et antirétroviraux.Le but de ce travail est d’améliorer la biodisponibilité par voie orale des médicaments à faible biodisponibilité par la mise au point d’un promoteur d’absorption. Pour y arriver nous avons adopté comme stratégie de développer un promoteur qui agit à la fois sur le passage passif et sur le passage actif des médicaments. Les études in vitro ont été réalisées en chambre de perméation d’Ussing adaptées par la société Biomécatronics SAS (BéthuneFrance). Dans la première partie de ce travail (Brevet), nous avons montré que l’utilisation d’une composition pharmaceutique et/ou diététique comprenant un extrait de plante(Hibiscus sabdariffa) pouvait augmenter la biodisponibilité in vitro des médicaments et des xénobiotiques qui passent par la voie paracellulaire comme le cisplatine (21 fois),l’oxaliplatine (11fois), la fluorescéine isothiocyanate-Dextran 4000 (3 fois), mais également les médicaments connus pour leur transport actif par la voie transcellulaire comme l’Efavirenz (7 fois) et l’Atazanavir (4 fois). Dans la seconde partie de ce travail, nous avons cherché à vérifier si notre promoteur d’absorption des médicaments a un effet sur la couche de mucus intestinale.Cette couche peut être un facteur limitant de passage des médicaments au travers de la barrière intestinale.Dans un premier temps (article 1), nous avons induit l’augmentation de la couche mucus au niveau du colon de rat après un prétraitement pendant une semaine avec le métronidazole. Puis nous avions confirmé (article 2) que l’administration par voie orale de deux antibiotiques le Cotrimoxazole (CTX) et le métronidazole (MTZ) pendant une semaine augmente la couche de mucus au niveau du côlon ; aussi nous avons montré qu’il existe une relation entre l’augmentation de la couche de mucus et la diminution de la conductance qui est l’index de transport passif des ions, des électrolytes et de certaines molécules à faibles poids moléculaires.De plus l’augmentation de la couche de mucus au niveau de l’intestin est responsable de la diminution du passage transépithélial des deux antirétroviraux dont l’utilisation est recommandée en première ligne par l’OMS (le.Ritonavir et l’Atazanavir) surles sujets porteurs du VIH (virus de l’immunodéficience humain). Après les traitements auMTZ et au CTX la sécrétion de l’Atazanavir augmente respectivement dans le côlon proximal de 2 et 4 fois et dans le côlon distal de 3 et 5 fois. On obtient également une sécrétion du Ritonavir de 5 et 10 fois dans le proximal et de 2 et 5 fois plus dans le distal.Le travail se poursuit par l’étude de l’effet de notre promoteur d’absorption des médicaments sur la couche de mucus intestinal.En conclusion, ce travail montre que l’on peut augmenter la biodisponibilité in vitroen utilisant les promoteurs de l’absorption des xénobiotiques qui agissent à la fois au niveau du transport passif et actifOral dosing is still seen as the silver bullet of drug administration, as it is cheaper andbetter adapted to patient comfort. However, oral route is still inaccessible to many drugssuch as biologics and biosimilars respectively certain anticancer drugs and antiretrovirals(ARV).The aim of this present study was to find new drugs enhancers that improve the oralbioavailability of drugs and xenobiotics. All the studies were realized in vitro using Ussingchambers technic. To achieve the set objective we used the strategy to develop drugenhancer which can modulate at the same time transcellular and paracellular pathways.In the first part of this study (patent) we have shown that the use of a pharmaceutical and /or a dietetic formulation containing a plant extract (Hibiscus sabdariffa) could increase thebioavailability in vitro in rats not only of cisplatin (21 fold), oxaliplatin (11 fold) andFluorescein Isothiocyanate-Dextran 4000 (FD4, 3 fold). All that drugs were transportedthrough intestinal barrier using paracellular pathway. In addition the study showed thatthis formulated enhancer can increased the bioavailability of Efavirenz (7 fold) andAtazanavir (4 fold) which are active transported.In order to assess the effect of new drugs enhancer on mucus thickness that limits thetransport of xenobiotic through intestinal barrier, we decide to evaluate his effect on passiveand active transport of drugs.In the second part of this study we have shown that after a week of pre-treatment of ratswith Metronidazole (MTZ, publication 1) and Cotrimoxazole (CTX, publication 2), the twomost commonly used antibiotics in the prophylaxis against opportunistic infections in HIV /AIDS, both increase colonic mucus thickness that affect directly passive intestinalpermeability by reducing conductance an index of passive transport through intestinalepithelium. In addition those antibiotics also entail a change in the transepithelialconductance and ARV fluxes. After MTZ and CTX treatment the secretion of Atazanavir(ATZ) increases respectively in the proximal colon by 2 to 4 fold and in the distal colon by 3to 5 fold respectively. Ritonavir (RTV) is poorly absorbed in control, after a week of pretreatmentwith MTZ and CTX one rather notices a secretion of RTV 5 to 10 fold higher in theproximal and 2 to 5 fold higher in the distal colon. The next study will be conducted toevaluate the effect of new drugs enhancer on mucus thickness layer.In conclusion, oral bioavailability of drugs and xenobiotics can be enhanced bypharmaceutical composition that contains herbal extract which increase passive and activetransport of drugs through intestinal barrier
32
Motz, Stephan A. [Verfasser]. "Combined assessment of dissolution and epithelial permeability of solid oral dosage forms / von Stephan A. Motz." 2007. http://d-nb.info/983385645/34.
Full text
33
Harvey, Benjamin Scott. "The effect of cannabinoids on cytokine evoked human colonic mucosal damage and Caco-2 epithelial permeability." Thesis, 2014. http://hdl.handle.net/2440/92814.
Full textAbstract:
Inflammatory bowel disease (IBD) is a disease characterised by two subtypes, ulcerative colitis (UC) and Crohn’s disease (CD). Both conditions can lead to inflammation and ulceration of the gastrointestinal mucosa. Treatments are available for IBD, however they can cause severe adverse effects and may not be useful in all patients. As a result, there is still an unmet need for novel IBD treatments. In animal models of colitis, cannabinoid (CB) agonists have shown efficacy in reducing inflammation. To further investigate this, we used a human colonic mucosal explant model to determine if CB agonists could attenuate mucosal damage. To induce damage in colonic mucosa, pro-inflammatory cytokines (that are elevated in IBD patients) were used. These included a combination of TNF-α + IL-1β and in other studies, IL-17A. Furthermore, we also tested if these cytokines modulated biochemical markers of inflammation. Immunohistochemistry was used to determine the identity of immune cells in the lamina propria of the mucosa and also localisation of IL-17A. Treatment of colonic mucosa with TNF-α + IL-1β induced damage characterised by luminal epithelial loss, crypt destruction and increased lymphocyte density. In addition, elevations in nitrite levels were found in TNF-α + IL-1β treated explants compared to controls. These damage parameters were attenuated by treatment with CB2R agonists. We found that PGE₂ concentration was significantly decreased after TNF-α + IL-1β incubation suggesting reductions in PGE₂ may partially mediate mucosal damage. IL-17A also induced a course of mucosal damage similar to that observed with TNF-α + IL-1β treatment, however no increase in lymphocyte density occurred. In this study, damage was reduced by the endocannabinoid anandamide as well as cannabidiol. We did not determine whether this effect was CB1R or CB2R mediated. Nitrite concentrations were not elevated after IL-17A treatment, however increased matrix metalloprotease activity was detected, suggesting this may mediate IL-17A induced mucosal damage. ELISA and western blotting was used to determine if the TNF-α + IL-1β combination we previously studied could influence IL-17A levels. There was no significant change in IL-17A expression, however basal expression of IL-17A was found in human colonic mucosa. This was confirmed by immunohistochemistry, showing extensive expression of IL-17A, particularly at the edge of the lumen. Therefore, IL-17A may also play a homeostatic or protective role against micro-organisms in the human colon. Cell culture studies examined the effects of cytokines and cannabinoids on Caco-2 epithelial permeability. In IBD, it has been established that increased mucosal permeability contributes to inflammation. TNF-α + IL-1β increased epithelial permeability; however this was not attenuated by CB ligands. IL-17A did not induce any significant increases in permeability. In conclusion, this thesis demonstrates that CB2R agonists may be useful in attenuating damage in human colonic mucosa induced by cytokines. Therefore, CB2R agonists may have utility as novel therapeutics in IBD. In addition, IL-17A which can be damaging in this model is also expressed in healthy human colonic mucosa, suggesting a homeostatic or protective role. It may be the case that excessive expression of IL-17A in IBD contributes to inflammation.Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2014
34
Khan, Niamat. "Comparative DNA‐Protein Interaction and Epithelial Tight Junctions Modulation Potential of Immunosuppressive Regime." Doctoral thesis, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-86AB-B.
Full text
35
Su, Kang-Cheng, and 蘇剛正. "Bile acids increase alveolar epithelial permeability via MAP kinase, cytosolic phospholipase A2, cyclooxygenase-2, PGE2, and junctional proteins." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/68972502580805930747.
Full textAbstract:
碩士國立陽明大學
急重症醫學研究所
101
Background and objective: Increasing evidence has shown that bile acid (BA) aspiration is associated with various lung diseases. The reaction of alveolar epithelium exposed to BAs is unknown. We hypothesize that BAs may induce alveolar permeability alteration and contribute to the pathogenesis of lung injury. Methods: Human alveolar epithelial cells were grown in monolayer and stimulated with a major component of BAs, chenodeoxycholic acid (CDCA). Transepithelial electrical resistance (TER) and paracellular fluxes were measured to assess permeability alteration. PGE2 production was measured, and its effect on TER and junctional proteins (JPs) was also examined. Reverse transcription-PCR and western blots were used to investigate the expression of mRNA and JPs. Results: CDCA induced significant p38 and JNK phosphorylation, cPLA2 and COX-2 mRNA expression, PGE2 production, TER reduction, and decay of JPs (including occludin, zonula occludens-1 [ZO-1], and E-cadherin, in which ZO-1 had maximal change). CDCA also increased paracellular fluxes, which was abolished by dexamethasone. Both CDCA and PGE2 contributed to TER reduction in an identical trend and a dose-response manner. PGE2 also reduced ZO-1 expression, which was similar to that observed by CDCA stimulation. Pretreatment with inhibitors of p38 (SB203580), JNK (SP600125), cPLA2 (mepacrine) and COX-2 (NS398) as well as dexamethasone reversed the CDCA-induced PGE2 production, TER reduction and decay of ZO-1. Conclusions: The increase in alveolar permeability was associated with decay of JPs.BAs may induce permeability alteration through the upregulation of MAPK, cPLA2, COX-2, PGE2 and JPs, which may contribute to the pathogenesis of BA-associated lung injury.
36
Baixinho, João Paulo Caseiro. "Development of curcumin lipid formulations for food applications: transport, permeability and safety evaluation on a mucus-secreting intestinal epithelial cell model." Master's thesis, 2018. http://hdl.handle.net/10362/52151.
Full textAbstract:
Curcumin is the main phenolic pigment extracted from turmeric, the powdered rhizome of Curcuma longa. It has been shown to exhibit antioxidant, antimicrobial, anti-inflammatory and anticarcinogenic activities however as health promoting agent, curcumin, is limited by its poor solubility in aqueous solution and its low bioavailability and therefore cannot be widely used in food and pharmaceutical processing industry.
The challenge addressed in this work was to produce curcumin formulations to enhance its characteristics and evaluate its permeability, transport and cytotoxicity on a stablished in vitro cell co-culture model that mimics the intestinal epithelium.
Solid lipid nanoparticles (SLN) and microparticles (SLM) have been visualised as a promising platform on development of formulations for food applications. Since traditional production methods possess a series of limitations, the processing by “green technologies” like supercritical carbon dioxide (scCO2) has been widely investigated. Through Particles from Gas Saturated Solutions (PGSS®) process, beeswax microparticles loaded with curcumin (9:1 (w/w)) were produced and characterized in terms of physicochemical properties: size, morphology, curcumin content and particles dispersion index. Operation process parameters were optimized and defined via response surface methodology and the best response was achieved at 160 bar, 73°C and 10% curcumin load. Under these conditions, encapsulation efficiency was 89.75 ± 2.23 % with a curcumin load of 8.98 % (w/w). Curcumin formulations underwent a digestive process and were tested for their cytotoxicity in Caco-2 monolayer.
A triple co-culture has been established and characterized for use as an in vitro intestinal model. To closely mimic the intestinal epithelium the production of mucus by the HT29-MTX-E12 cell line cultured together with the Caco-2 enterocytes and M-cells like phenotype was observed. The model was used to evaluate the transport and permeability of free and encapsulated curcumin and its permeability was stablished as a value of 1.0 x 10-7 cm/s.
37
Banga, Amiraj. "Functional Effects of Carbon Nanoparticles on Barrier Epithelial Cell Function." 2012. http://hdl.handle.net/1805/2918.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)As mass production of carbon nanoparticles (CNPs) continues to rise, the likelihood of occupational and environmental exposure raises the potential for exposure‐related health hazards. Although many groups have studied the effects of CNPs on biological systems, very few studies have examined the effects of exposure of cells, tissues or organisms to low, physiologically relevant concentrations of CNPs. Three of the most common types of CNPs are single wall nanotubes (SWNT), multi wall nanotubes (MWNT) and fullerenes (C60). We used electrophysiological techniques to test the effects of CNP exposure (40 μg/cm2 – 4 ng/cm2) on barrier function and hormonal responses of well characterized cell lines representing barrier epithelia from the kidney (mpkCCDcl4) and airways (Calu‐3). mpkCCDcl4 is a cell line representing principal cell type that lines the distal nephron in an electrically tight epithelia that aids in salt and water homeostasis and Calu‐3 is one of the few cell lines that produces features of a differentiated, functional human airway epithelium in vivo. These cell lines respond to hormones that regulate salt/water reabsorption (mpkCCDcl4) and chloride secretion (Calu‐3). In mpkCCDcl4 cells, after 48 hour exposure, the transepithelial electrical resistance (TEER) was unaffected by high concentrations (40 – 0.4 μg/cm2) of C60 or SWNT while lower, more relevant levels (< 0.04 μg/cm2) caused a decrease in TEER. MWNT decreased TEER at both high and low concentrations. CNT exposure for 48 hour did not change the transepithelial ion transport in response to anti‐diuretic hormone (ADH). In Calu‐3 cells, after 48 h of exposure to CNPs, fullerenes did not show any effect on TEER whereas the nanotubes significantly decreased TEER over a range of concentrations (4 μg/cm2‐0.004 ng/cm2). The ion transport response to epinephrine was also significantly decreased by the nanotubes but not by fullerenes. To look at the effect of exposure times, airway cells were exposed to same concentrations of CNPs for 24 and 1h. While the 48 h and 24 h exposures exhibited similar effects, there was no effect seen after 1h in terms of TEER or hormonal responses. In both the cell lines the magnitude of the transepithelial resistance change does not indicate a decrease in cellular viability but would be most consistent with more subtle changes (e.g., modifications of the cytoskeleton or changes in the composition of the cellular membrane). These changes in both the cell lines manifested as an inverse relationship with CNP concentration, were further corroborated by an inverse correlation between dose and changes in protein expression as indicated by proteomic analysis. These results indicate a functional impact of CNPs on epithelial cells at concentrations lower than have been previously studied and suggest caution with regard to increasing CNP levels due to increasing environmental pollution.
38
Mündörfer, Marco [Verfasser]. "Combined assessment of drug dissolution and epithelial permeability : implementation of online TEER measurement and extension to BCS class III and IV compounds / von Marco Mündörfer." 2010. http://d-nb.info/1009514245/34.
Full text
39
Li, Pin. "Effects of carbon nanotubes on airway epithelial cells and model lipid bilayers : proteomic and biophysical studies." Thesis, 2014. http://hdl.handle.net/1805/5968.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)Carbon nanomaterials are widely produced and used in industry, medicine and scientific research. To examine the impact of exposure to nanoparticles on human health, the human airway epithelial cell line, Calu-3, was used to evaluate changes in the cellular proteome that could account for alterations in cellular function of airway epithelia after 24 h exposure to 10 μg/mL and 100 ng/mL of two common carbon nanoparticles, singleand multi-wall carbon nanotubes (SWCNT, MWCNT). After exposure to the nanoparticles, label-free quantitative mass spectrometry (LFQMS) was used to study differential protein expression. Ingenuity Pathway Analysis (IPA) was used to conduct a bioinformatics analysis of proteins identified by LFQMS. Interestingly, after exposure to a high concentration (10 μg/mL; 0.4 μg/cm2) of MWCNT or SWCNT, only 8 and 13 proteins, respectively, exhibited changes in abundance. In contrast, the abundance of hundreds of proteins was altered in response to a low concentration (100 ng/mL; 4 ng/cm2) of either CNT. Of the 281 and 282 proteins that were significantly altered in response to MWCNT or SWCNT, respectively, 231 proteins were the same. Bioinformatic analyses found that the proteins common to both kinds of nanotubes are associated with the cellular functions of cell death and survival, cell-to-cell signaling and interaction, cellular assembly and organization, cellular growth and proliferation, infectious disease, molecular transport and protein synthesis. The decrease in expression of the majority proteins suggests a general stress response to protect cells. The STRING database was used to analyze the various functional protein networks. Interestingly, some proteins like cadherin 1 (CDH1), signal transducer and activator of transcription 1 (STAT1), junction plakoglobin (JUP), and apoptosis-associated speck-like protein containing a CARD (PYCARD), appear in several functional categories and tend to be in the center of the networks. This central positioning suggests they may play important roles in multiple cellular functions and activities that are altered in response to carbon nanotube exposure. To examine the effect of nanotubes on the plasma membrane, we investigated the interaction of short purified MWCNT with model lipid membranes using a planar bilayer workstation. Bilayer lipid membranes were synthesized using neutral 1, 2-diphytanoylsn-glycero-3-phosphocholine (DPhPC) in 1 M KCl. The ion channel model protein, Gramicidin A (gA), was incorporated into the bilayers and used to measure the effect of MWCNT on ion transport. The opening and closing of ion channels, amplitude of current, and open probability and lifetime of ion channels were measured and analyzed by Clampfit. The presence of an intermediate concentration of MWCNT (2 μg/ml) could be related to a statistically significant decrease of the open probability and lifetime of gA channels. The proteomic studies revealed changes in response to CNT exposure. An analysis of the changes using multiple databases revealed alterations in pathways, which were consistent with the physiological changes that were observed in cultured cells exposed to very low concentrations of CNT. The physiological changes included the break down of the barrier function and the inhibition of the mucocillary clearance, both of which could increase the risk of CNT’s toxicity to human health. The biophysical studies indicate MWCNTs have an effect on single channel kinetics of Gramicidin A model cation channel. These changes are consistent with the inhibitory effect of nanoparticles on hormone stimulated transepithelial ion flux, but additional experiments will be necessary to substantiate this correlation.
40
Phillips, Brett E. "Occludin regulates permeability and cell division in retinal pigmented epithelium cells." 2007. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1853/index.html.
Full text
41
Han, Taishien, and 韓台賢. "Effects of Clematis Armandi extracts on permeability and short circuit current (Isc) across frog skin epithelium." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/28797961243720219679.
Full textAbstract:
碩士國立中山大學
生物科學系研究所
90
Summary Clmatis Armandi has been used frequently in traditional Chinese medicine for the treatment of diuretic symptoms. The mechanism of its action is unclear. Possible action of this substance may involve alternation of electrolyte transport through the epithelia membranes. In this study，transepithelial conductance of frog skin was measured in vitro in voltage-clamped Ussing chambers. Adding Clematis Armandi extracts to apical surface induced a conductance increment of 1.21 μS and an apical to serosal Isc of 28.78 μA/cm2. The Isc can not be completely blocked by apical application of amiloride. Nifedipine and TEA had no effect on Clematis Armandi induced Isc decrease. These data indicate that frog skin is highly responsive to the concentrated Clematis Armandi extracts. The increase in Isc reflects changes in transepithelial transport of Na+ ions modulated at apical membrane. The enormous increase in transepithelial conductance suggests that in additional to enhancement of amiloride-sensitive Na+ channels, Clematis Armandi may also modulate other pathways, such as Cl- ion channel modulation, which needs further investigation.
42
Lin, Zhe-Wei, and 林哲瑋. "Effect of Rhei Rhizoma Extract on Short-circuit Current and Ion Permeability Across the Frog Skin Epithelium." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/aezuw6.
Full textAbstract:
碩士國立中山大學
生物科學系研究所
97
Rhei Rhizoma, also named as rhubarb or Da Huang, has been used widely in oriental traditional medicine in treating constipation and edema. However, though much affection has been paid to the make of components on pharmaceutical mechanisms, few studies have been conducted to reveal chemical and physical mechanism of these effects. Studies have shown that diarrhea causes imbalance of chloride and sodium ion movements via epithelium, we wondered if similar mechanism may apply to Rhei Rhizoma, a herbal drug which has been used to treat constipation in oriental medicine for thousands of years. The measurement of short-circuit current (Isc) has been used widely to estimate the ion transportation between mucosal and serosal side of epithelium. In this study, we used Ussing chamber technique to examine the alternation in membrane potential and short-circuit currents. The result shows, at default, the Isc of frog skin we used was at 59.23±5.58μA/cm², and the conductance was at 1.11±0.50μA/cm²•mV. The lnjection of 1ml RRE to mucosal side of the frog skin leaded to a 90% elevation of the Isc. Followed by the application of Amiloride (sodium channel inhibitor) and Chlorothiazide (chloride channel inhibitor) to mucosal side of the epithelial skin, the observed Isc were then reduced 136% and 33% respectively. If RRE were applied after the adding of Amiloride or Chlorothiazide to the frog skin, then the Isc of the skin elevated only 24% and 70% respectively. These results show that Rhei Rhizoma Extract (RRE) significantly increases Isc upon application to the mucosal side of the skin epithelium. Amiloride and Chlorothiazide will both inhibit the Isc induced by RRE, indicating activation of chloride channel and Amiloride-sensitive sodium channel of the epithelial tissue by RRE. After the regular Ringer solution used in the preparation was replaced by Na-free and Cl-free Ringer solution, the inhibition of Isc by RRE application could still be observed although the inhibition was trivia. These results indicate that RRE acts dominantly on mucosa side of the epithelium and can be used to enhance sodium transport and to stimulate the secretion of Cl- in the epithelium.
43
Su, Hsuan-yin, and 蘇宣穎. "EFFECTS OF PORIA COCOS WOLF EXTRACT (PCWE) ON SHORT-CIRCUIT CURRENT AND ION PERMEABILITY ACROSS THE EPITHELIUM OF PIG COLON." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/ghar46.
Full textAbstract:
碩士國立中山大學
生物科學系研究所
95
PCWE has been used widely in oriental traditional medicine in treating edema and diarrhea. Recent studies have shown that PCWE may also have anti-tumor and anti-inflammation acts. However, few studies have been conducted to reveal the mechanisms of these effects. In the present study, we tried to elucidate the mechanisms by investigating the effects on PCWE on the regulation of ion transport across the epithelial membranes of colon, which is also useful in explaining the anti-diarrhea and anti-edema effects. Alternation in membrane potential and short-circuit current (Isc) were examined using the Ussing chamber technique. Our results showed that PCWE decreased Isc upon application to the apical side. Amiloride inhibited this Isc induced by PCWE indicating that PCWE acted on amiloride-sensitive sodium channel of the epithelium. However, when PCWE was applied to the serosal side, the Isc was not changed, indicating a minimal influence of this substance on ATP-driving Na+/K+ counter transporters. Our data also showed that the Isc decreased by PCWE could be inhibited by bumetanide and chlorothiazide (Cl‾ channel inhibitors). We therefore concluded that PCWE could both enhance sodium transport and stimulate the secretion of Cl‾ in colon epithelium.
44
McCanna, David. "Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic Products." Thesis, 2009. http://hdl.handle.net/10012/4338.
Full textAbstract:
The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes.
The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.