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Circadian regulation of digestive system function and its disturbances due to external factors
Běloušková, Klára ; Sumová, Alena (advisor) ; Balounová, Kateřina (referee)
Circadian clocks regulate the behavior of cells in living organisms in 24hour periods. They react to environmental influences and, by synchronizing with them, ensure optimal cell function and the overall health of the organism. Biological clocks in the gastrointestinal tract and their functions can be influenced by several factors, including the timing of food intake or the influence of the microbiome. The correct timing of food intake can be essential in maintaining the functional physiology of the organism as well as the appropriate composition of the gut microbiome. Disruption of the synchronization between these factors and the biological clock in the gastrointestinal tract leads to disharmony of the organism, its improper function and the development of disease. The timing of food intake and the cultivation of an appropriate microbiome is critical to maintaining optimal health and should not be neglected by the public.
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Role of intestinal circadian clock in epithelial transport, proliferation, and tumourigenesis
Soták, Matúš ; Pácha, Jiří (advisor) ; Bendová, Zdeňka (referee) ; Herichová, Iveta (referee)
AABBSSTTRRAACCTT The molecular circadian clock enables anticipation of environmental changes. In mammals, clocks are ubiquitously present in almost all tissues and they are comprised of transcriptional-translational feedback loops of the so-called clock genes. The central clock represents the intrinsic pacemaker which is located in suprachiasmatic nuclei (SCN) of hypothalamus and synchronizes peripheral clocks. Clockwork system in alimentary tract and its regulatory link to intestinal functions are poorly understood. Therefore the objective of the thesis was to characterize molecular clock in particular parts of the rat intestine and to elucidate its link to the intestinal transport, regulation of cell cycle and neoplastic transformation in colonic tissue. We used quantitative RT-PCR (qPCR) to determine circadian profiles of mRNA expression of clock genes in the epithelium of duodenum, jejunum, ileum, and colon of rat. Furthermore, we analysed the expression of genes coding sodium chloride transporters and channels as well as cell cycle regulators in colon. To focus more precisely on different structures of intestinal epithelia we used laser capture microdissection. In addition, we performed Ussing chamber measurements to determine the colonic electrogenic transport. To study the contribution of circadian...
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In vitro and ex vivo study of drug-drug interactions of antivirals on intestinal membrane transporters
Halodová, Veronika ; Červený, Lukáš (advisor) ; Vokřál, Ivan (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Veronika Halodová Supervisor: doc. PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: In vitro and ex vivo study of drug-drug interactions of antivirals on intestinal membrane transporters Tenofovir (TFV) is the first-line agent in the treatment of hepatitis B virus (HBV) infection for patients aged over 12 years and one of the first-line choices for the combination antiretroviral therapy (cART) of infections caused by human immunodeficiency virus (HIV). Two commercially available prodrugs have been developed for oral administration of TFV, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide fumarate (TAF). These prodrugs increase TFV membrane permeability and oral bioavailability. One of the factors that can affect the bioavailability of orally administrated drugs is active transport mediated by efflux transporters, mainly by P-glycoprotein (ABCB1, P-gp) and Breast cancer resistance protein (ABCG2, BCRP). It has been already proved that TDF and TAF are substrates of both of these transporters. The goal of this diploma thesis was to use in vitro and ex vivo models of intestinal barrier to assess the impact of the efflux transporters on TDF and TAF transport in the intestine and on their...
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Effect of anthelmintics on the transport of drugs in the intestine
Štefanová, Anna ; Vokřál, Ivan (advisor) ; Červený, Lukáš (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Bc. Anna Štefanová Supervisor: PharmDr. Ivan Vokřál, Ph.D. Title of diploma thesis: Effect of anthelmintics on the transport of drugs in the intestine Several classes of drugs are currently available for the treatment of helminthiasis in humans and animals, the so-called anthelmintics. Most of these drugs are administered by the oral route, where absorption into the systemic circulation occurs through the intestinal barrier. However, the course and extent of this absorption may be limited by biotransforming enzymes and transport proteins, in particular the family of so-called ATP-binding cassette transporters. These transporters are capable of returning many xenobiotics, including many drugs, back into the lumen of the gut and are the first line of defence against the entry of these substances into the body. An important representative of this group of transporters is P-glycoprotein, which is known for its broad substrate specificity. On this transporter, drugs can act as substrates but also as inhibitors and/or inducers, which may lead to the risk of drug-drug interactions. There is relatively little information about the effect of anthelmintics on P-glycoprotein inhibition. The most studied...
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In vitro and ex vivo study of drug-drug interactions of antivirals on intestinal membrane transporters
Halodová, Veronika ; Červený, Lukáš (advisor) ; Vokřál, Ivan (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Veronika Halodová Supervisor: doc. PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: In vitro and ex vivo study of drug-drug interactions of antivirals on intestinal membrane transporters Tenofovir (TFV) is the first-line agent in the treatment of hepatitis B virus (HBV) infection for patients aged over 12 years and one of the first-line choices for the combination antiretroviral therapy (cART) of infections caused by human immunodeficiency virus (HIV). Two commercially available prodrugs have been developed for oral administration of TFV, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide fumarate (TAF). These prodrugs increase TFV membrane permeability and oral bioavailability. One of the factors that can affect the bioavailability of orally administrated drugs is active transport mediated by efflux transporters, mainly by P-glycoprotein (ABCB1, P-gp) and Breast cancer resistance protein (ABCG2, BCRP). It has been already proved that TDF and TAF are substrates of both of these transporters. The goal of this diploma thesis was to use in vitro and ex vivo models of intestinal barrier to assess the impact of the efflux transporters on TDF and TAF transport in the intestine and on their...
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Role of intestinal circadian clock in epithelial transport, proliferation, and tumourigenesis
Soták, Matúš
AABBSSTTRRAACCTT The molecular circadian clock enables anticipation of environmental changes. In mammals, clocks are ubiquitously present in almost all tissues and they are comprised of transcriptional-translational feedback loops of the so-called clock genes. The central clock represents the intrinsic pacemaker which is located in suprachiasmatic nuclei (SCN) of hypothalamus and synchronizes peripheral clocks. Clockwork system in alimentary tract and its regulatory link to intestinal functions are poorly understood. Therefore the objective of the thesis was to characterize molecular clock in particular parts of the rat intestine and to elucidate its link to the intestinal transport, regulation of cell cycle and neoplastic transformation in colonic tissue. We used quantitative RT-PCR (qPCR) to determine circadian profiles of mRNA expression of clock genes in the epithelium of duodenum, jejunum, ileum, and colon of rat. Furthermore, we analysed the expression of genes coding sodium chloride transporters and channels as well as cell cycle regulators in colon. To focus more precisely on different structures of intestinal epithelia we used laser capture microdissection. In addition, we performed Ussing chamber measurements to determine the colonic electrogenic transport. To study the contribution of circadian...
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Sexual dimorphism of rat gut microbiota composition and intestinal immunity
Kalousová, Pavla ; Kovařík, Miroslav (advisor) ; Jílek, Petr (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biological and Medical Sciences Candidate: Pavla Kalousová Supervisor: PharmDr. Miroslav Kovařík, Ph.D. Title: Sexual dimorphism of rat gut microbiota composition and intestinal immunity Background and Aim: Many factors can influence the composition of gut microbiota and the immune system. It is well-known that one of those factors is sex. This sexual dimorphism can lead to a specifically adjusted treatment of diseases for different gender and nutritional interventions. This study focuses on analysing sexual differences in gut microbiota and intestinal immunity in adult rats. Methods: Caecal content from 12-week-old female and male Wistar rats were collected and analysed by DNA-sequencing technique to characterize microbiota composition. ELISA test was performed to quantify the concentration of IgA in faeces and gut wash. Flow cytometry determined the concentration of IgA-coating bacteria in faecal samples. Results: Metagenomic analysis revealed that female gender presents 1 phylum, 4 families, 13 genera, and 13 species which are not present in male rats. Only one male-specific colonization was observed at the species level. Quantitative analysis showed a higher proportion of Firmicutes phylum in males which was associated with...
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In vitro and ex vivo study of drug-drug interactions of antiretrovirals on intestinal ATP-binding drug transporters
Jahodová, Michaela ; Červený, Lukáš (advisor) ; Vokřál, Ivan (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Bc. Michaela Jahodová Supervisor: PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: In vitro and ex vivo study of drug-drug interactions of antiretrovirals on intestinal ATP-binding drug transporters The absorption of orally administered drugs takes place especially in the intestine, where it can affect by the activity of drug's ABC transporters located on the apical membrane of the intestinal epithelium. Study of drug interactions in intestinal ABC transporters is essential to ensure effective and safe pharmacotherapy. Testing of bi- directional transport on Caco-2 cells is generally the preferred method for in vitro evaluation of substrates and inhibitors of ABC transporters. Drawbacks of the Caco-2 model increase the need and necessity to introduce new models. A great potential is the involvement of ex vivo methodologies in the human or rat intestine. The aim of the work was to introduce an in vitro methodology using the Caco-2 cell monolayer and the ex vivo methodology of precision-cut rat intestinal slices. By the bi-directional transport method, we analyzed drug interactions of the model substrate P-gp and BCRP Rhodamine 123 (RHD123) and clinically-used tenofovir...
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Sexual dimorphism of rat gut microbiota composition and intestinal immunity
Kalousová, Pavla ; Kovařík, Miroslav (advisor) ; Jílek, Petr (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biological and Medical Sciences Candidate: Pavla Kalousová Supervisor: PharmDr. Miroslav Kovařík, Ph.D. Title: Sexual dimorphism of rat gut microbiota composition and intestinal immunity Background and Aim: Many factors can influence the composition of gut microbiota and the immune system. It is well-known that one of those factors is sex. This sexual dimorphism can lead to a specifically adjusted treatment of diseases for different gender and nutritional interventions. This study focuses on analysing sexual differences in gut microbiota and intestinal immunity in adult rats. Methods: Caecal content from 12-week-old female and male Wistar rats were collected and analysed by DNA-sequencing technique to characterize microbiota composition. ELISA test was performed to quantify the concentration of IgA in faeces and gut wash. Flow cytometry determined the concentration of IgA-coating bacteria in faecal samples. Results: Metagenomic analysis revealed that female gender presents 1 phylum, 4 families, 13 genera, and 13 species which are not present in male rats. Only one male-specific colonization was observed at the species level. Quantitative analysis showed a higher proportion of Firmicutes phylum in males which was associated with...
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Study of interactions of antiviral drugs with intestinal drug efflux ABC transporters
Huličiak, Martin ; Červený, Lukáš (advisor) ; Vokřál, Ivan (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Martin Huličiak Supervisor: PharmDr. Lukáš Červený, Ph.D Title of diploma thesis: Study of interactions of antiviral drugs with intestinal drug efflux ABC transporters P-gp, MRP2 and BCRP are efflux transporters, members of the family of ATP binding cassette (ABC) transporters. These transporters are located on the apical membrane of the intestinal epithelium, where they may limit absorption of orally administered drugs. Study of drug interactions with/on intestinal efflux transporters is necessary to provide safe and effective treatment. The Caco-2 cell line is FDA recommended in vitro model of intestinal barrier and it is used for bidirectional testing of substrates and inhibitors of ABC transporters in preclinical research. However, this methodology has several shortcomings, so the need of introduction of new experimental models is increasing and the ex vivo method based on human or rat intestine is a promising option. Precision-cut intestinal slices (PCIS) represent a mini-model of the organ and contain all types of cells of the tissue. We used both in vitro model using Caco-2 cell monolayers for drug transport study and in our lab established ex vivo method of PCIS for accumulation study...
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