Browsing by Subject "permeability"
Now showing items 1-8 of 8
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(2017)Monissa sairauksissa suoliston seinässä voidaan havaita tulehdus, läpäisevyyden kasvu ja mikrobiston muutoksia verrattuna terveisiin verrokkeihin. Tästä syystä suoliston mikrobiston muokkaamisella ja anti-inflammatorisilla bakteerilajeilla on potentiaalia kyseisten sairauksien hoidossa sekä preventiossa. Tulehduksen hoidossa tehokkaaksi menetelmäksi on osoittautunut mm. ulosteensiirrot, mutta sen anti-inflammatorisesta vasteesta vastaavat mekanismit ovat vielä osittain epäselviä. Tämän tutkielman kirjallisuuskatsauksessa tarkasteltiin suoliston mikrobiston ja läpäisevyyden häiriöiden vaikutuksia terveyteen ja erityisesti nivelreumaan. Nivelreumapotilailla on tyypillisesti kohonnut suoliston läpäisevyys, mutta sen merkitys sairauden etenemisessä ja patogeneesissä on vielä tuntematon. Suoliston mikrobiston häiriöt ja läpäisevyyden muutokset saattavat aiheuttaa immuunireaktion, joka voi johtaa nivelen rakenteisiin kohdistuvan autoimmuniteetin puhkeamiseen. Kokeellisessa osiossa tutkittiin suolistosta eristettyjen potentiaalisesti anti-inflammatoristen Propioni acnes –bakteerin ja toistaiseksi tuntemattoman linjan (27cc1) bakteerin vaikutuksia suoliston läpäisevyyteen. Koe suoritettiin Caco2-enterosyyttisolulinjalla ja sen muodostaman epiteelin läpäisevyyttä arvioitiin TER (transepithelial electrical resistance) -mittauksilla. Valituilla bakteereilla ei havaittu kokeissa merkittävää vaikutusta epiteelin läpäisevyyteen in vitro.
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(2020)Ischemic heart failure is the leading cause of death in the world. The disease is caused by coronary heart disease, in which the narrowed coronary arteries limit oxygen- and nutrient-rich blood from reaching the myocardial tissue. Obstructed arterial blood flow can cause myocardial necrosis and scarring. Scar tissue is non-contractile and poorly elastic. It can thus compromise the pumping capacity of the heart. Current medical and interventional therapies have only very limited efficacy to reduce myocardial scarring. Preclinical and clinical research efforts are underway to generate myocardial scar-reducing and regenerative therapies. In the field of cardiac cellular therapies, the delivery of cells has conventionally been based on intramyocardial injections. However, epicardial patches have been demonstrated to reduce scarring and promote myocardial healing. In addition to merely being a carrier or cover for the cellular transplant, the biomembrane of the patch can also be considered as an active element for the patch’s therapeutic activity. Thus, the properties of the biomembrane can have a major impact on both the cellular and the therapeutic tissue response. The aim of this Master's thesis was to build a standardized test set up to study the properties of the biomembrane. Biomembrane permeability to small (glucose, lactate) molecules and different size proteins was investigated. In addition, the set up was modified to enable the investigation of biomembrane properties on the survival of the grafted cells. Finally, the test set up was evaluated by studying the properties of ProxiCorTM, the biomembrane currently used together with autologous atrial micrografts (AAMs) in epicardial patch. As a result, the set up was successfully constructed and characterized. The ProxiCorTM membrane demonstrated permeability to both small molecules and proteins, and a stable pH was maintained across the membrane. ProxiCorTM enabled traverse serum-induced proliferation of cells compared to the control impermeable membrane. Taken together, these results prove the functionality of the test set up and thus support its further development.
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(2020)Ischemic heart failure is the leading cause of death in the world. The disease is caused by coronary heart disease, in which the narrowed coronary arteries limit oxygen- and nutrient-rich blood from reaching the myocardial tissue. Obstructed arterial blood flow can cause myocardial necrosis and scarring. Scar tissue is non-contractile and poorly elastic. It can thus compromise the pumping capacity of the heart. Current medical and interventional therapies have only very limited efficacy to reduce myocardial scarring. Preclinical and clinical research efforts are underway to generate myocardial scar-reducing and regenerative therapies. In the field of cardiac cellular therapies, the delivery of cells has conventionally been based on intramyocardial injections. However, epicardial patches have been demonstrated to reduce scarring and promote myocardial healing. In addition to merely being a carrier or cover for the cellular transplant, the biomembrane of the patch can also be considered as an active element for the patch’s therapeutic activity. Thus, the properties of the biomembrane can have a major impact on both the cellular and the therapeutic tissue response. The aim of this Master's thesis was to build a standardized test set up to study the properties of the biomembrane. Biomembrane permeability to small (glucose, lactate) molecules and different size proteins was investigated. In addition, the set up was modified to enable the investigation of biomembrane properties on the survival of the grafted cells. Finally, the test set up was evaluated by studying the properties of ProxiCorTM, the biomembrane currently used together with autologous atrial micrografts (AAMs) in epicardial patch. As a result, the set up was successfully constructed and characterized. The ProxiCorTM membrane demonstrated permeability to both small molecules and proteins, and a stable pH was maintained across the membrane. ProxiCorTM enabled traverse serum-induced proliferation of cells compared to the control impermeable membrane. Taken together, these results prove the functionality of the test set up and thus support its further development.
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(2022)Indomethacin is in a BCS-classification class two drug, meaning it has poor solubility but good permeability. Because of this solubility is a limiting factor for it reaching bloodcirculation. Amorphous form has better solubility than crystalline form. Most common problems with amorphous form are poor stability and process technical problems. In this study Indomethacin was combined with two different kind of polymers that were prepared by hot-melt extrusion. By hot-melt extrusion we can get more stable product than pure amorphous drug. These polymers were polyvinylpyrrolidone (PVPK179 and polyvinylpyrrolidonevinylacetate (PVPVA). They were prepared with Indomethacin 1:1 mass ratio. The aim was to study these extrudates and their stability, cumulative release and especially permeability. By using differential scanning calorimetry, X-ray diffraction and polarized light microscopy it was possible to analyze whether the drug was amorphous or crystalline. In the study it was found that by using hot-melt extrusion it was possible to make amorphous combinations of Indomethacin and polymers. Their permeability was between crystalline and amorphous form. PVPK17-Indomethacin combination had better permeability than PVPVA-Indomethacin combination. On the other hand PVPVA-Indomethacin had better cumulative release than PVPK17-Indomethacin combination
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(2010)Biopharmaceutical Classification System (BCS) is a scientific framework for classifying drug substances based on their aqueous solubility and intestinal permeability. When combined with dissolution of the drug product, the BCS takes into account three major factors that govern the rate and extent of drug absorption. For a BCS biowaiver, the in vitro dissolution study may be used as a surrogate for in vivo bioequivalence studies. Currently, BCS I drugs are accepted as biowaiver candidates by EMEA, FDA and WHO. EMEA and WHO also accept class III drugs in some conditions. The main difficulty in classifying drugs according to BCS is the determination of permeability. Biopharmaceutics Drug Distribution Classification System (BDDCS) was introduced to provide a surrogate for permeability. If the major route of elimination is metabolism, then the drug exhibites high permeability. There are two parts in this master thesis. BCS and BDDCS are discussed and evaluated in the literature part. The focus is in the BCS III drugs. The purpose of the experimental part is to evaluate BCS III drug, hydrochlorothiazide as a biowaiver candidate. Solubility of the drug substance and dissolution of the drug product was determined. Aim of the permeability studies with Caco-2 cells were to study if hydrochlorothiazide permeates by passive diffusion across the monolayer. Importance of paracellular diffusion was evaluated by opening tight junctions with EDTA. Influence of dissolution rate was evaluated by theoretical simulation. According to the results of this study, hydrochlorothiazide has good solubility in aqueous buffer. It has been reported to diffuse passively across the epithelial cells but in this study permeability increased when concentration decreased. This may be due to active transport. Hydrochlorothiazide diffuses partially through the tight junctions. Dissolution of the hydrochlrothiazide tablet was very rapid. Drug eliminates almost entirely by metabolism, it is also BDDCS class III drug. EMEA and WHO accept BCS III drugs as biowaiver candidate if dissolution rate is very rapid. According to this, hydrochlorothiazide could be suggested as a biowaiver candidate. There are also other issues to be considered, for example excipients used in tablets. Since hydrochlorothiazide has been discovered to be absorbed in the upper part of the small intestine, the influence of excipients is especially important. This possible influence should be evaluated before the final decision of biowaiver.
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(2011)QSPR (Quantitive structure property relationship) describes relationship between descriptors and biological activity. Therefore, QSPR models are useful tools in drug discovery. The literature review summarizes existing corneal, intestinal and blood brain barrier permeability models. The most common descriptors are hydrophobicity, polar surface and H-bonding capability. Also, the size of molecule may have influence on permeability even though the results are sometimes contradictory. Descriptors might have limiting values such as those presented in Lipinski's ‖rule of five‖. Drug candidate should not have 'rule of 5' values outside of the useful range, otherwise the per oral absorption of the compound may be compromised. In the literature review the transporter activity in cornea, intestine and blood brain barrier is described. Currently, many QSPR-models have been developed to predict interactions of drug candidates with transporters. The purpose of experimental part was to build in silico -model of corneal passive permeability for early ocular drug discovery. QSPR-model was built using permeability data and molecular descriptors of 54 molecules. Corneal permeability coefficients in rabbits were obtained from the literature. Octanol-water partitition coefficient at pH 7,4 (logD) and the total number of hydrogen bonds were the descriptors in the final model. The final equation was log(permeability coefficient) = -3,96791 - 0,177842*Htotal + 0,311963*logD(pH7,4). For this model R2 was 0,77 ja Q2 was 0,75. The model was evaluated using an external data set of 15 compounds and by pharmacokinetic modeling. Predicted permeability coefficients were used to simulate the aqueous humour concentrations of sevent compounds at steady-state. In addition corneal absorption coefficient (Kc) was simulated for 13 compounds and these values were compared to predicted permeability. The predicted permeability coefficients correlated well with experimental permeability coefficients. In addition aqueous humour concentrations can be simulated in steady state using predicted (QSPR) permeability coefficients. The final QSPR-model may be used in ocular drug discovery and development.
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(2016)In the literature review of this study, the focus was on biofilms that certain microbes produce, and their potential use in food industry. Biofilms consist of microbial cells and extracellular products, e.g., polysaccharides. Pullulan as an exopolysaccharide has many industrial applications and the aim of this study was to explore a new potential alpha-glucan, dextran, and especially its ability to form a stand-alone film. Pullulan and dextran were separately mixed in de-ionized water. The dynamic viscosities of dextran and pullulan solutions were determined. Film formation of dextran was not successful, not even with sorbitol as a plasticizer. The optical properties, water vapor and oxygen permeabilities and tensile strengths of pullulan films were studied. Additionally, Whatman42-filter material was coated with or immersed in dextran solution. Hence the changes in tensile strength and permeability values between a well-known material and dextran treated material could be detected. Pullulan films had low haze values (2.1–3.9%) and they were transparent to UVA-, UVB- and visible light. The tensile strength values of pullulan films were 47–53 MPa. For filter paper, the corresponding values were 10 MPa and application of dextran coating increased it to 15–19 MPa. All polysaccharide solutions exhibited Newtonian behavior and their relative viscosities were <10 mPa, 5% pullulan with viscosity around 20 mPa as an exception. Pullulan solutions had higher viscosities than dextran solutions. The air permeabilities were 10–50 ml/min for pullulan films, 10 ml/min for dextran-sorbitol film, 200 ml/min for dextran film and 200–500 ml/min for Whatman42 material. The oxygen permeability values for pullulan films were <0,1 cm3·μm m-2·d-1·kPa-1. Based on results in this study, pullulan films are impermeable to oxygen. As the films tolerated water vapor poorly, pullulan might be a potential component in packages made of composite materials, as individual packaging material in dry environment or possibly chemically modified to obtain better resistance to water vapor. Our results show that without additional modifications dextran does not form a continuous self-supporting films in these conditions.
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(2020)High blood pressure has been shown to increase intestinal permeability, which is associated with several diseases such as inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS). Recently, renin-angiotensin system (RAS) components, the main regulators of blood pressure, have been found to be produced also locally in several tissues e.g. intestine, heart and brain. In the intestine, the local RAS participates in the regulation of inflammation. However, little is known of the functionality of the local intestinal RAS components and their involvement in the regulation of the intestinal barrier function. Conventional angiotensin-converting enzyme (ACE)-angiotensin receptor type 1 (AT1R) axis and the alternative angiotensin-converting enzyme 2 (ACE2)- Mas receptor axis have opposing functions in the body. The disbalance between the two pathways has been associated with different pathophysiological processes. This in vitro study aimed to assess the direct effect of proinflammatory angiotensin II (Ang II) via the activation of AT1R on intestinal permeability of 8-10-week-old Balb/c mice. Jejunum and colon samples were collected and mounted to the Ussing chamber with different Ang II concentrations or a combination of Ang II and AT1R antagonist losartan. Angiotensin (1-7) (Ang (1-7)), a Mas receptor agonist, was also examined for its possible beneficial effect on reducing gut permeability and on alleviating the harmful effects of Ang II. Transepithelial resistance (TER) and short-circuit current (Isc) were analyzed as indicators of the permeability. Given the importance of the tight junction proteins to paracellular permeability, the levels of occludin, claudin-1 and claudin-4 were determined with Western blot from jejunum and colon samples incubated for 75 min under similar conditions used in the Ussing chamber. Ang II increased the paracellular permeability via the activation of AT1R in jejunum. Additionally, Ang (1-7) tended to alleviate the negative effects of Ang II. Changes in tight junction protein levels partly were in accordance with the permeability findings. The fluorescence permeability marker (9Å) used mimics the size of disaccharides. There is evidence that TER measures the changes in the paracellular ion and water transport and as no alterations in TER values were observed we suggest that Ang II increases the flux of macromolecules via the activation of AT1R in jejunum. No significant changes in permeability or in the electrophysiological values were observed in colon after incubation with peptides.
Now showing items 1-8 of 8