| 1. |
- Ahlin, Gustav, 1977-
(författare)
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In vitro and in silico prediction of drug-drug interactions with transport proteins
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Drug transport across cells and cell membranes in the human body is crucial for the pharmacological effect of drugs. Active transport governed by transport proteins plays an important role in this process. A vast number of transport proteins with a wide tissue distribution have been identified during the last 15 years. Several important examples of their role in drug disposition and drug-drug interactions have been described to date. Investigation of drug-drug interactions at the transport protein level are therefore of increasing interest to the academic, industrial and regulatory research communities. The gene expression of transport proteins involved in drug transport was investigated in the jejunum, liver, kidney and colon to better understand their influence on the ADMET properties of drugs. In addition, the gene and protein expression of transport proteins in cell lines, widely used for predictions of drug transport and metabolism, was examined. The substrate and inhibitor heterogeneity of many transport proteins makes it difficult to foresee whether the transport proteins will cause drug-drug interactions. Therefore, in vitro assays for OCT1 and OATP1B1, among the highest expressed transport proteins in human liver, were developed to allow investigation of the inhibitory patterns of these proteins. These assays were used to investigate two data sets, consisting of 191 and 135 registered drugs and drug-like molecules for the inhibition of OCT1 and OATP1B1, respectively. Numerous new inhibitors of the transport proteins were identified in the data sets and the properties governing inhibition were determined. Further, antidepressant drugs and statins displayed strong inhibition of OCT1 and OATP1B1, respectively. The inhibition data was used to develop predictive in silico models for each of the two transport proteins. The highly polymorphic nature of some transport proteins has been shown to affect drug response and may lead to an increased risk of drug-drug interactions, and therefore, the OCT1 in vitro assay was used to study the effect of common genetic variants of OCT1 on drug inhibition and drug-drug interactions. The results indicated that OCT1 variants with reduced function were more susceptible to inhibition. Further, a drug-drug interaction of potential clinical significance in the genetic OCT1 variant M420del was proposed. In summary, gene expression of transport proteins was investigated in human tissues and cell lines. In vitro assays for two of the highest expressed liver transport proteins were used to identify previously unknown SLC transport protein inhibitors and to develop predictive in silico models, which may detect previously known drug-drug interactions and enable new ones to be identified at the transport protein level. In addition, the effect of genetic variation on inhibition of the OCT1 was investigated.
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| 2. |
- Alenius, Malin, 1974-
(författare)
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Treatment Response in Psychotic Patients in a Naturalistic Setting : Classification, Genes, Drugs, Insight and Social Networks
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many patients with psychotic symptoms respond poorly to treatment. Various approaches have been made to classify these patients according to treatment response. However, existing classifications have been criticized for various reasons and a new classification system is needed. Further, no satisfactory explanation of the poor treatment response has been apparent. The general aim of this thesis was therefore to develop and validate a new classification method of functional remission in a naturalistic population of patients with psychosis and to utilize this classification to investigate the population from genetic, drug treatment, insight and social network points of view. Data for this cross-sectional study of patients (n=123) attending the Psychosis Outpatient Care clinic in the county of Jönköping, Sweden, were obtained from patient interviews, blood samples and information from patient files. The new classification method CANSEPT, which combines the CAN rating scale (CAN), the UKU side effect rating scale (SE) and the patient’s previous treatment history (PT), showed validity in discriminating the patients and was accepted well by the patients. CANSEPT was used to group the patients in the other studies in this thesis. The results indicated that the gene polymorphism ABCB1 3435T, was related to worse significant social and clinical needs for patients on olanzapine, while the polymorphism DRD2 Taq1 A1 was related to a greater risk of significant side effects; especially if male, or taking strong dopamine D2-receptor antagonistic drugs. Drug treatment factors were also related to treatment response; longer duration of untreated prodromal and early psychosis was seen for patients with current significant social and clinical needs and non-adherence to treatment was associated with worse significant side effects. Worse treatment outcomes also appeared to be associated with smaller social network groups, worse insight into illness, poorer knowledge of warning signs and worse coping strategies. In summary, CANSEPT was shown to be a useful valid, multidimensional tool for classification of treatment response. Gene polymorphisms, duration of untreated illness, non-adherence to treatment, social networks and knowledge should be taken into consideration when investigating inadequate treatment response.
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| 3. |
- Alm, Henrik, 1974-
(författare)
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Proteomic Characterization of Induced Developmental Neurotoxicity
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The developing brain goes through a number of developmental periods during which it displays an increased sensitivity to exogenous disturbances. On such period is the so called “Brain growth spurt” (BGS) which in humans takes place starting from the third trimester of pregnancy and throughout the first few years of life. The corresponding period in rats and mice is the first postnatal weeks. Exposure to relatively modest concentrations of the brominated flame retardant PBDE-99 during the second week of life in mice causes a more or less permanent impairment in the ability of the animals to adjust properly to environmental changes at adulthood. This “late response on early exposure” reflects the long-term consequences of disrupting the developing brain during a sensitive time period. The cellular mechanisms underlying the behavioral effects are far from clear. To address the initial damage occurring around the time of exposure, the approach used in this thesis is to use proteomics to analyze the effects of PBDE-99 on protein expression soon (24 hours) after exposure of the neonatal mouse on postnatal day (PND) 10.The thesis comprises the effects on the proteome in three distinct brain parts: cerebral cortex, striatum and the hippocampus. In addition, an in vitro model was developed and used to evaluate the PBDE-99 effects on cultured cerebral cortex cells from embryonic rat brains. Gel-based proteomics (2D-DIGE) coupled to MALDI- or ESI-MS has been used throughout for the proteomics experiments, but other techniques aimed at analyzing both proteins and mRNA have also been used to better characterize the effects. Even if the protein complements expressed by the different brain parts and separated with 2D-DIGE are seemingly similar, the effects are apparently specific for the different brain regions. In hippocampus, PBDE induces effects on proteins involved in metabolism and energy production, while the effects in striatum point towards effects on neuroplasticity. PBDE-99 changes the expression of cytoskeletal proteins in the cerebral cortex 24 hours after exposure. Interestingly, in vitro exposure of cerebral cortex cells to a PBDE-99 concentration in the same order of magnitude as in the in vivo neonatal brain also induces cytoskeletal effects, in the absence of cytotoxicity. This may suggest effects on regulatory aspects of cytoskeletal dynamics such as those involved in neurite sprouting. This thesis also addresses the problems involved in presenting proteomics data. Many of the available methods and approaches for presenting transcriptomics data are not suitable for isoform rich protein data. Modifications of existing methods and the development of a new approach (DEPPS) is also presented. Most importantly, the thesis presents the application and usefulness of proteomics as hypothesis generating techniques in neurotoxicology.
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| 4. |
- Andersson, Maria, 1976-
(författare)
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Chemically Induced DNA Damage in Extended-term Cultures of Human Lymphocytes
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Generation of DNA damage is regarded to be an important initial event in the development cancer. Consequently, a battery of tests have been developed to detect different types of genotoxic effects in order to be able to predict the potential genotoxicity and mutagenicity of chemicals, including both pharmaceutical drugs and various types of environmental and occupational agents, as well as dietary factors. The aim of this thesis was to evaluate whether the combination of the comet assay and the extended-term cultures of human lymphocytes (ETC) can be used as an alternative in vitro system to more commonly used transformed mammalian cell lines, and primary cell cultures from humans, when testing the potential genotoxicity of chemicals. Using the comet assay, a panel of reference compounds showed that the ETC were found to detect the DNA-damaging effects with no remarkable difference to what has been reported in other cell types. Moreover, in comparison with a well-established rodent cell line, the mouse lymphoma L5178Y cells, the ETC showed similar sensitivity to the DNA damaging effects of the genotoxic agents hydrogen peroxide and catechol. Although there was an interindividual variation in induced DNA damage and the subsequent repair when using ETC from different blood donors, it did not seem to be of crucial importance for the identification of DNA-damaging agents. The demonstrated difference in sensitivity to catechol-induced DNA damage between freshly isolated peripheral lymphocytes and ETC may very well be due to their different proliferative status but despite this difference, both in vitro systems were able to identify catechol as a DNA-damaging agent at the same concentration.Based on these results, it is proposed that the ETC and the comet assay are a useful combination when testing for the potential DNA damaging effects of chemicals. Representing easily cultivated cells possessing the normal human karyotype, where one blood sample can be used for numerous experiments performed over a long time, extended-term cultures appear to be a useful alternative, both to transformed mammalian cell lines, and primary cell cultures from humans. In fact, the extended-term lymphocytes, with or without S9 and/or lesion specific DNA repair enzymes, should be used more frequently when screening for the potential genotoxicity of chemicals.
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| 5. |
- Arefalk, Anna, 1974-
(författare)
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New Methods for the Synthesis of 3-Substituted 1-Indanones : A Palladium-Catalyzed Approach
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In medicinal chemistry, there is a constant need for new preparative methods, both to make the synthesis process more effective, and to increase the accessibility to a wide variety of compounds. A number of different approaches can be used to attain these goals. Transition metal catalysis is generally performed under mild conditions, providing both regio- and chemoselective reactions. Thus, it offers an attractive means of preparation of complex drug candidates. Two additional methodologies used to increase the preparative efficiency are one-pot protocols and controlled microwave heating. One-pot and multi-component reactions are less time consuming than step-by-step reactions, and microwave heating has been used to considerably shorten the reaction times. This thesis describes a new palladium-catalyzed, one-pot reaction producing racemic acetal-protected 3-hydroxy-1-indanones from ethylene glycol vinyl ether and triflates of salicylic aldehydes. The triflates were prepared using controlled microwave heating. The reaction sequence starts with a regioselective internal Heck coupling, followed by an annulation cascade. By including secondary amines in the reaction mixture, the reaction was further developed into a three-component reaction delivering racemic acetal-protected 3-amino-1-indanones. This new method was utilized for the synthesis of primary, secondary and tertiary aminoindanones. Finally, by using enantiopure t-butyl sulfinyl imines, derived from salicylic aldehyde triflates and ethylene glycol vinyl ether as starting materials in a closely related type of palladium coupling–annulation sequence, a stereoselective protocol providing enantiomerically pure 3-amino-1-indanones was developed. To demonstrate an application in medicinal chemistry, the enantiopure 3-amino-1-indanones were incorporated as P2 and/or P2´ substituents into active HIV-1 protease inhibitors.
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| 6. |
- Arvela, Riina K
(författare)
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Palladium-Catalysed Carbon–Carbon Coupling Reactions : Focusing on Microwave Heating, Low Catalyst Concentrations, Aqueous Conditions, Regioselectivity and Medicinal Chemistry Applications
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is widely accepted that palladium is one of the most useful catalysts in organic chemistry, and many palladium(0)-catalysed carbon–carbon bond-forming reactions have been developed over the years. In addition, the ever-growing need for more environmentally benign processes in the chemical industry has driven scientists to look for greener options while developing new methodologies for organic synthesis. This thesis describes a series of studies on Suzuki and Heck coupling reactions in water and the application of palladium(0) catalysis to the development of new HIV-1 integrase inhibitors. The previously described 'transition-metal-free Suzuki-type coupling' reaction was shown to take place due to sub-ppm levels of palladium contaminants present in the commercially available sodium carbonate base. Based on this finding, a new, microwave-assisted Suzuki protocol utilizing ppb/ppm levels of palladium in water was developed. This methodology was adapted to terminal Heck coupling, although the scope of the protocol was found to be rather limited. Finally, both Suzuki and Heck reaction processes were successfully scaled up to 100 mmol using an automated batch stop-flow microwave apparatus. As the methodologies utilizing ultralow palladium concentrations were not applicable to aryl chlorides, attention was shifted towards palladium on carbon. This simple catalyst, together with microwave heating employing simultaneous cooling, was found to be beneficial in the Suzuki coupling of aryl chlorides with phenylboronic acid in water. Ligand-controlled internal arylation of ethylene glycol vinyl ether with aryl halides was shown to be possible in water alone without any additives. Reactions were run under air, using conventional heating and the products formed were isolated as aryl methyl ketones in good to excellent yields. The electron-rich (dippp)2Pd complex was shown to be beneficial for the microwave-assisted internal arylation of some aryl chlorides. Furthermore, the active role of the hydroxyl group of ethylene glycol vinyl ether in the formation of a cationic intermediate leading to internal Heck coupling product was elucidated. Finally, to demonstrate the usefulness of palladium(0) catalysis in the development of new pharmaceutical entities, a series of HIV-1 integrase inhibitors was synthesised and evaluated in strand transfer assays and in vitro. Based on the results and docking studies performed, valuable information related to the structure–activity relationship was obtained.
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| 7. |
- Ax, Anna, 1975-
(författare)
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Cyclic Sulfamide HIV-1 Protease Inhibitors : Design, Synthesis and Modelling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ten years ago, the first protease inhibitor targeting the human immunodeficiency virus (HIV) was approved for clinical use. Highly active antiretroviral therapy (HAART), which combined protease and reverse transcriptase inhibitors, quickly became the standard therapy for treating patients infected with HIV and Acquired Immune Deficiency Syndrome (AIDS). Nevertheless, last year the AIDS pandemic reached its highest level ever. Many infected patients, mainly in the developing countries, are still without treatment. Among those patients who receive treatment, an increase in drug resistance and new-infection with drug-resistant strains are seen. To come to terms with these problems, new drugs that are efficient against resistant strains and can be produced at low cost are needed.In this study, we have focused our research efforts on cyclic sulfamides active as HIV-1 protease inhibitors. Distinctive to this compound class, as compared to the inhibitors so far approved for clinical use, was the incorporation of a water mimic that displaces the structural water (W301) observed in the X-ray crystal co-complexes. The first part of the study was aimed at understanding the rationale behind the nonsymmetric binding mode that the inhibitor adopted when bound to the enzyme. Symmetric and nonsymmetric inhibitors were synthesized and the structure-activity relationships and preferable binding modes were rationalized with the help of Comparative Molecular Field Analysis (CoMFA).In the second part of the study, an attempt was made to reduce the size of these inhibitors. As a result, the traditional P1/P1' substituents were removed, while the P2/P2' substituents were elongated in an attempt to reach between the binding sites. The design hypothesis was shown to be successful and inhibitors possessing nanomolar activity were identified.
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| 8. |
- Bengtsson, Jörgen, 1976-
(författare)
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Developmental Aspects of Drug Transport Across the Blood-Brain Barrier
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The developmental aspect of drug transport across the blood-brain barrier (BBB) was investigated. Microdialysis was used to study unbound morphine BBB transport at different ages in sheep. An in vitro study was performed to find differentially expressed genes in brain capillary-rich fractions of the brain in rats of different ages. Microdialysis and brain-to-plasma ratios were used to study the contribution of breast cancer resistance protein (Bcrp) to the transport of nitrofurantoin (NTF) across the BBB of rats during development as well as in adult rats and mice. A method of analysing morphine and its metabolites in plasma and microdialysis samples was developed and validated. The in vivo recovery of deuterated morphine, used as a calibrator in microdialysis experiments, was not affected by the presence of morphine in the tissue. A net influx of morphine was observed in premature lambs and adult sheep, in contrast to the efflux seen in other species. This influx decreased with age, indicating that the morphine transport across the BBB changes with age. In contrast, the transport of the morphine metabolite morphine-3-glucuronide (M3G) did not change with age. Microarray data indicated that several active transporters are differentially expressed with age. Moreover, the mRNA expression levels of Abcg2 (Bcrp) and Slc22a8 (organic anion transporter 3) changed with age when quantified using real-time polymerase chain reaction. In contrast, the expression of Abcb1 (P-glycoprotein) and occludin (a tight junction protein) did not change with age. In rats, the brain distribution of NTF decreased with age due to increased protein binding in plasma. The concentration ratio of unbound NTF across the BBB was low in the adult rat, due to intra-brain metabolism and/or efflux by other transporters. Bcrp did not appear to have a significant contribution in the developing rat or in knock-out mice compared to wild-type controls with regard to NTF BBB transport. In conclusion, in vitro studies showed that the expression levels of some genes changed with age, presumably affecting subsequent drug distribution to the brain. Further, in vivo studies showed that distribution across the BBB changed with age for morphine but not for M3G or NTF.
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| 9. |
- Berggren, Sofia, 1973-
(författare)
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Drug Transport and Metabolism in Rat and Human Intestine
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the aims of this thesis was to investigate the involvement of efflux proteins, such as the P-glycoprotein (Pgp), in the drug transport in different regions of the rat and the human intestine. The intestinal extrusion of intracellularly formed CYP3A4 metabolites, including whether this extrusion might be mediated by Pgp, was also studied. The model drugs used were local anaesthetics (LA), which have been evaluated for inflammatory bowel disease, such as ropivacaine, lidocaine and bupivacaine. The intestinal permeability to LAs was found to be high throughout all intestinal regions of the rat and human intestine. Results from the Ussing chamber model indicated only minor efflux involvement as the drug permeability was higher in the serosa to mucosa transport direction than in the opposite direction. However, the involvement of efflux in the absorption of LAs could not be verified using in situ single-pass perfusion of rat jejunum. The extrusion of the ropivacaine metabolite, 2´,6´-pipecoloxylidide (PPX), was polarized to the mucosal reservoir of the Ussing chamber for both rat and human intestinal samples, and was probably not caused by any Pgp involvement. The expression levels of CYP3A4 and efflux transporters were consistent with the enzymes’ activity in human intestine. PPX formation was mediated by CYP3A4 in human intestine, and cyp2c and cyp2d in rat intestine. Species differences were observed, as PPX was formed in rat colon, but not human colon. In conclusion, the permeability of ropivacaine, lidocaine and bupivacaine was not subjected to efflux transport of significance for their intestinal uptake. The transport of ropivacaine metabolites to the mucosal compartment was probably not mediated by Pgp. The Ussing chamber model showed consistent results with those from intestinal microsomes as far as intestinal metabolism is concerned, making it a suitable model for investigations of the interplay of efflux and metabolism.
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| 10. |
- Bergman, Ebba, 1977-
(författare)
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The Hepatobiliary Transport of Rosuvastatin In Vivo
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In vivo studies of hepatobiliary disposition are challenging. The hepatobiliary system is complex, as its physiological localization, complex cellular structure with numerous transporters and enzymes, and the interindividual variability in protein expression and biliary flow will all affect the in vivo disposition of a drug under investigation. The research included in this thesis has focused on the involvement of hepatic transport proteins in the hepatobiliary disposition of rosuvastatin. The impact that several transport inhibitors had on the pharmacokinetics of rosuvastatin was investigated in healthy volunteers and in pigs. The effects were considerable, following inhibition of sinusoidal transport proteins by cyclosporine and rifampicin. These inhibitors significantly reduced the hepatic extraction of rosuvastatin by 50 and 35%, respectively, and the plasma exposure increased by factors of 9.1 and 6.3, respectively. Drug-drug interactions (DDI) resulting in markedly higher plasma exposures are important from a drug safety perspective as increased extrahepatic exposure of statins is associated with an increased risk of severe side-effects, such as myopathy which in rare cases could develop into rhabdomyolysis. The DDI caused by cyclosporine and rifampicin can probably be attributed to inhibition of hepatic uptake transporters. In contrast, inhibition of canalicular transporters by imatinib did not significantly affect the pharmacokinetics of rosuvastatin, which suggests that the intracellular concentration of the inhibitor in the hepatocyte was insufficient to affect the transport of rosuvastatin, or that imatinib is not a sufficiently potent inhibitor in vivo. Furthermore, gemfibrozil administered as a single dose into the jejunum in healthy volunteers and pigs did not affect the plasma or biliary pharmacokinetics of rosuvastatin. The previously reported DDI in humans upon repeated dosing with gemfibrozil might be explained by the accumulation of metabolites able to affect the disposition of rosuvastatin. The investigations presented in this thesis conclude that transport proteins are of considerable importance for the hepatobiliary disposition of rosuvastatin in vivo. The Loc-I-Gut catheter can be applied for the investigation of biliary accumulation and to determine bile specific metabolites, however it has limitations when conducting quantitative measurements. In the porcine model, hepatic bile can be collected for up to six hours and enables the determination of the hepatic extraction in vivo.
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