In chronic inflammatory diseases like asthma or rheumatoid arthritis, erroneous and exaggerated accumulation of leukocytes in a tissue inadvertently causes the body harm. Several efficient anti-inflammatory drugs exist, for example corticosteroids and cyclo-oxygenase inhibitors. However, these drugs have potent and diverse effects and often act by inhibiting events subsequent to initiation of the inflammatory response, leading to more or less severe side-effects, especially when used in high doses for long periods of time. For this reason, strategies aimed at early inhibition of recruitment and activation of leukocytes have been suggested as safer and more specific approaches to reduce inflammation. Leukocyte adhesion to activated endothelium is a prerequisite to the following activation and extravasation, and takes place in the initial phase of inflammation. By using a model that allows leukocytes to adhere to tumour necrosis factor (TNF)-activated endothelial cells, thus mimicking aspects of an inflammatory reaction, we found that uridine, 4-thiouridine and isomaltitol could all reduce adhesion. This suggested that they may have anti-inflammatory potential. We therefore tried the three substances in a Sephadex-induced lung inflammation model and found that uridine and 4-thiouridine have several anti-inflammatory effects, such as being able to reduce leukocyte accumulation, decrease TNF protein levels and partly inhibit the oedema induced by Sephadex. Isomaltitol turned out to have immunomodulating, rather than anti-inflammatory, effects, which could be of interest in diseases where inadequate inflammatory responses are a problem.

Cyclooxygenase-2 (COX-2) catalyses prostaglandin synthesis from arachidonic acid during inflammation. COX-2 is expressed in the normal brain and is induced in neurological disorders. There is evidence that COX-2 is involved in secondary events leading to cell death in the brain. The first objective was to study the expression of COX-2 in the brain after kainate (KA)-induced limbic seizures and brain trauma caused by controlled cortical contusion (CCC) and fluid percussion injury (FPI). COX-2 mRNA and protein were strongly induced by limbic seizures in the hippocampus, amygdala and piriform cortex. CCC and FPI resulted in an upregulation of COX-2 mainly in the dentate gyrus and cortex, with differences in expression levels in these regions between the models. The second objective was to evaluate the effects of selective COX-2 inhibitors on delayed cell death. Limbic seizures induced cell death in parts of the hippocampus, amygdala and functionally connected regions. Treatment with the selective COX-2 inhibitor rofecoxib 8 h after KA injection significantly reduced hippocampal cell death. Pre-treatment with the COX-2 inhibitor nimesulide augmented acute seizures with increased mortality and thus the effect of nimesulide on delayed cell death could not be evaluated. Effects of rofecoxib on trauma-induced cell death were studied in the FPI model. FPI induced delayed cell death mainly in the ipsilateral cortex and bilaterally in the dentate gyrus. Rofecoxib treatment, starting directly after injury was caused, had no protective effect against cell death. The results suggest that COX-2 inhibition may be both detrimental and beneficial and largely dependent on the time schedule of treatment. COX-2 inhibitors might thus be of value as a neuroprotective treatment approach, provided that the role of COX-2 and the time course of effects of its metabolites in the brain are elucidated.

Proteins have such structural features that they may interact with different types of surfaces by all possible forces, i.e., electrostatic, hydrogen bonding, hydrophobic. In this thesis two different types of coatings for fused silica capillaries aimed to eliminate such interactions have been studied. The first is a covalent, electroosmosis-free coating with polyacrylamide (PAA) and the second involves a non-covalent coating with the quaternary ammonium compound N, N-didodecyl –N, N- dimethylammonium bromide (DDAB) with a strong anodic electroosmosis. Optimal conditions regarding efficiency and resolution were established by variations of the composition and ionic strengths of buffers at pH below the isoelectric point of the proteins. To achieve high efficiency and resolution the choice of buffer constituents was extremely important. The PAA coating was very stable at neutral and acidic conditions. Ammonium acetate (0.12 M) and ammonium hydroxyacetate (0.15 M) both at pH 4 provided the best separations with plate numbers up to 1 700 000 plate/m that is among the highest reported in the literature. Capillaries coated with DDAB were stable enough to, without recoating, permit consecutive separations of the proteins up to 9 hours (90 injections). High apparent efficiencies (over 1 million plates/m) were achieved with ammonium acetate (0.07 M), ammonium hydroxyacetate (0.08 M) and sodium phosphate (0.1 M) at pH 4. Zone broadening was studied by determination of the variance contributions from all main parameters. Significant variances were contributions from longitudinal diffusion, capillary curvature, injection plug, detector time response and detector slit width while other variances, e.g., variances for Joule heat and vertical sedimentation were negligible. The remaining undetermined variance may have its origin in all types of relatively slow interactions including adsorption onto the capillary surfaces and protein-buffer component interactions. The results indicate that the latter is the main cause to zone broadening in protein separations.

The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyacrylate (PA) gels with dodecyl- (C12TAB), and cetyltrimethylammonium bromide (C16TAB), as well as hyaluronate gels with cetylpyridinium chloride, have been studied. Kinetic experiments have been performed on macro- as well as microgels, using micromanipulator assisted light microscopy for the latter. A surfactant diffusion controlled deswelling model has been employed to describe the deswelling. The deswelling kinetics of PA microgels have been shown to be controlled by surfactant diffusion through the stagnant layer surrounding the gel, as the surface phase is relatively thin for the major part of the deswelling. For macroscopic PA gels the surface phase is thicker, and the kinetics with C12TAB were therefore also influenced by diffusion through the surface phase, while for C16TAB they were dominated by it. Relevant parameters have also been determined using equilibrium experiments. An irregular, balloon-forming deswelling pattern, mainly found for macrogels, as well as unexpectedly long lag times and slow deswelling for microgels, are reported and discussed. The microstructure of fully collapsed PA/C12TAB complexes has been studied using small-angle X-ray scattering. A cubic Pm3n structure was found at low salt concentration, which melted into a disordered micellar phase as the salt concentration was increased. Further increasing the salt concentration dissolved the micelles, resulting in no ordering.

In risk assessment of risk chemicals, variability in susceptibility in the population is an important aspect. The health hazard of a pollutant is related to the internal exposure to the chemical, i.e. the target dose, rather than the external exposure. The target dose may be calculated by physiologically based pharmacokinetic (PBPK) modeling. Furthermore, variability in target dose may be estimated by introducing variability in the physiological, anatomical, and biochemical parameters of the model. Data on these toxicokinetic model parameters may be found in the scientific literature. Since the early seventies, a large number of experimental inhalation studies of the kinetics of several volatiles in human volunteers have been performed at the National Institute for Working Life in Solna. To this day, only very limited analyses of these extensive data have been performed. A Bayesian analysis makes it possible to merge a priori knowledge from the literature with the information in experimental data. If combined with population PBPK modeling, the Bayesian approach may yield posterior estimates of the toxicokinetic parameters for each subject, as well as for the population. One way of producing these estimates is by so-called Markov-chain Monte Carlo (MCMC) simulation. The aim of the thesis was to apply the MCMC technique on previously published experimental data. Another objective was to assess the reliability of PBPK models in general by the combination of the extensive data and Bayesian population techniques. The population kinetics of methyl chloride, dichloromethane, toluene and styrene were assessed. The calibrated model for dichloromethane was used to predict cancer risk in a simulated Swedish population. In some cases, the respiratory uptake of volatiles was found to be lower than predicted from reference values on alveolar ventilation. The perfusion of fat tissue was found to be a complex process that needs special attention in PBPK modeling. These results provide a significant contribution to the field of PBPK modeling of risk chemicals. Appropriate statistical treatment of uncertainty and variability may increase confidence in model results and ultimately contribute to an improved scientific basis for the estimation of occupational health risks.

Genetic and environmental factors interact to determine the individual vulnerability to develop ethanol dependence. The neurobiological mechanisms underlying these processes are not fully understood. Endogenous opioid peptides have been suggested to contribute. Brain opioids mediate ethanol reward and reinforcement via actions on the mesocorticolimbic dopamine system. This thesis focuses on environmental factors and investigates the impact of the early-life environment on adult voluntary ethanol consumption. The possible involvement of opioid peptides in environmental influences on adult ethanol consumption was examined using an experimental animal model. Maternal separation with short 15 min separations (MS15) was used to simulate a safe environment whereas prolonged 360 min separations (MS360) simulated an unsafe environment. Control rats were subjected to normal animal facility rearing (AFR). The separations were performed daily from postnatal day 1 to 21. Long-term ethanol consumption was registered using a two-bottle or a four-bottle free-choice paradigm in adult male and female ethanol-preferring AA (Alko, Alcohol), ethanol-avoiding ANA (Alko, Non-Alcohol) and non-preferring Wistar rats. In addition, analyses of immunoreactive Met-enkephalin-Arg6Phe7 (MEAP), dynorphin B (DYNB) and nociceptin/orphanin FQ (N/OFQ) peptide levels were performed after maternal separation as well as after voluntary ethanol drinking. In male rats, MS15 was related to lower ethanol consumption and these rats preferred lower concentrations, whereas MS360 was associated with an increased risk for higher consumption and/or preference for higher ethanol concentrations. Differences in basal opioid levels were observed in MS15 and MS360 rats. Furthermore, the ethanol-induced effects on opioid peptides in adults were dependent on the early environment. Female rats, on the other hand, were less affected or unaffected by maternal separation both in terms of ethanol consumption and neurobiological effects. Taken together, voluntary ethanol drinking, preference for low or high ethanol concentrations and opioid peptides in brain areas related to reward and reinforcement, motivation and stress were influenced by postnatal maternal separation in a sex dependent manner. The early environment thus had profound impact on the adult brain and the individual propensity for high ethanol drinking. A deranged endogenous opioid system contributed to these effects and may act as a mediator for long-term environmental influence on voluntary ethanol consumption.

The general aim of this thesis was to evaluate a newly designed and constructed miniaturized rotating disk apparatus for in vitro dissolution rate measurements of different drug substances from all of the classes in the Biopharmaceutical Classification System (BCS). The new equipment is based on a low volume flow-through cell of Plexiglas, a gold plated magnetic bar and a special designed press. The disk of drug substance (approx. 5 mg) is placed eccentrically in the bar. Rotation speeds were set with a graded magnetic stirrer. An external HPLC pump delivered a continuous flow of aqueous medium to the flow-through cell during dissolution testing. A reversed phase high-performance liquid chromatography system using diode array detection (RP-HPLC-DAD) was coupled online to the new equipment. The injections from the miniaturized rotating disk outlet into the quantifying HPLC system were controlled by a six-position switching valve. The injection volumes from the valve and the autosampler, used for the external standards, were statistically evaluated to match each other volumetrically. No analyses were longer than three minutes, using isocratic mode. A traditional USP rotating disk apparatus was used as a reference system and the two instruments were shown to be statistically dissimilar in the numerical dissolution rate values probably due to different hydrodynamics, but had approximately the same precision/repeatability. When correlating the logarithmic values of the in vitro dissolution rate (G) with the apparent solubility (S), using shake-flask methodology in the solubility studies, the two apparatuses gave the same correlation patterns. Further correlation studies were done where the media components were altered by the use of different buffer species or additives into the buffers, such as inorganic salts. Chemometric tools, e.g. orthogonal partial least squares (OPLS), were used to better evaluate the most influential factors for G and S in different media. The most significant factor for a model basic drug substance (terfenadine) was pH, followed by the ionic strength (I) and added sodium chloride in one of the media. However, the surfactants in the Fasted State Simulated Intestinal Fluid (FaSSIF-V2) were found to be insignificant for G and S in this study (using a 95% confidence interval). The new miniaturized apparatus is a promising prototype for in vitro dissolution rate measurements both for early screening purposes and in dissolution testing during drug development, but needs further instrumental improvements.

A nonparametric population approach is now accessible to a more comprehensive network of modelers given its recent implementation into the popular NONMEM application, previously limited in scope by standard parametric approaches for the analysis of pharmacokinetic and pharmacodynamic data. The aim of this thesis was to assess the relative merits and downsides of nonparametric models in a nonlinear mixed effects framework in comparison with a set of parametric models developed in NONMEM based on real datasets and when applied to simple experimental settings, and to develop new diagnostic tools adapted to nonparametric models. Nonparametric models as implemented in NONMEM VI showed better overall simulation properties and predictive performance than standard parametric models, with significantly less bias and imprecision in outcomes of numerical predictive check (NPC) from 25 real data designs. This evaluation was carried on by a simulation study comparing the relative predictive performance of nonparametric and parametric models across three different validation procedures assessed by NPC. The usefulness of a nonparametric estimation step in diagnosing distributional assumption of parameters was then demonstrated through the development and the application of two bootstrapping techniques aiming to estimate imprecision of nonparametric parameter distributions. Finally, a novel covariate modeling approach intended for nonparametric models was developed with good statistical properties for identification of predictive covariates. In conclusion, by relaxing the classical normality assumption in the distribution of model parameters and given the set of diagnostic tools developed, the nonparametric approach in NONMEM constitutes an attractive alternative to the routinely used parametric approach and an improvement for efficient data analysis.

The enzymes CYP27A1 and CYP7B1 are widely expressed in various human tissues and perform catalytic reactions in cholesterol homeostasis and endocrine signaling. We have investigated the metabolism of a synthetic oxysterol. In this study, we show that CYP27A1 is the enzyme responsible for a 28-hydroxylation of this oxysterol and that the rate of CYP27A1-mediated metabolism is relatively slow. This may give an explanation for the prolonged inhibitory effects on cholesterol biosynthesis that have been shown for this oxysterol. The current study contributes to the knowledge of synthetically produced oxysterols and their potential use as cholesterol lowering drugs. In two studies we investigated CYP7B1-mediated metabolism of different sex hormones. Our data indicate that CYP7B1 may carry out a previously unknown catalytic reaction involving an androgen. Taken together the data suggest that varying steroid concentrations in cells and tissues may be important for CYP7B1-dependent metabolism of sex hormones and sex hormone precursors. CYP7B1-mediated hydroxylation of sex hormones may influence the cellular levels of these steroids and may be a potential pathway for elimination of the steroids from the cell. Some known CYP7B1 substrates are agonists for ERα and ERβ but the reported role(s) of CYP7B1 for ER action are not fully understood. In the last study we investigated the role(s) of CYP7B1-mediated metabolism for ER-mediated action. Our data indicate that CYP7B1-mediated conversion of steroids that affect ER-mediated response into their 7α-hydroxymetabolites will result in loss of action. This indicates that CYP7B1 may have an important role for regulation of ER-mediated processes in the body. In summary, results from this thesis contribute to the knowledge on the metabolism of synthetic oxysterols of potential use as cholesterol lowering drugs and the role(s) of CYP7B1-mediated metabolism for processes related to the functions of sex hormones. / Disputationsordförande;Professor Eva Brittebo, Inst. för Biovetenskap, Avd. för Toxikologi, Uppsala Universitet, UppsalaBetygsnämndens ledamöten; Docent Lena Ekström, Inst. för Laboratoriemedicin, Avd. för Klinisk Kemi, Karolinska Universitetssjukhuset, HuddingeDocent Ulf Diczfaluzy, Inst. för Laboratoriemedicin, Avd. för Klinisk Kemi, Karolinska Universitetssjukhuset, HuddingeProfessor Agneta Oskarsson, Inst. BVF, Avd. för farmakologi och toxikologi, SLU, Uppsala

Biologically active peptides are important for many physiological functions in the human body and therefore serve as interesting starting points in drug discovery processes. In this work the neuropeptide substance P 1–7 (SP1–7, H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-OH), which has been demonstrated to reduce neuropathic pain and attenuate opioid withdrawal symptoms in animal models, has been addressed in a medicinal chemistry program with the overall aim of transforming this bioactive peptide into more drug-like compounds. Specific binding sites for this neuropeptide have been detected in the brain and the spinal cord. Interestingly, the smaller neuropeptide endomorphin-2 (EM-2, H-Tyr-Pro-Phe-Phe-NH2) also interacts with these binding sites, although 10-fold less efficient. In this work the structure–activity relationship of SP1–7 and EM-2, regarding their affinity to the SP1–7 binding site was elucidated using alanine scans, truncation, and terminal modifications. The C-terminal part of both peptides, and especially the C-terminal phenylalanine, was crucial for binding affinity. Moreover, the C-terminal functional group should preferably be a primary amide. The truncation studies finally resulted in the remarkable discovery of H-Phe-Phe-NH2 as an equally good binder as the heptapeptide SP1–7. This dipeptide amide served as a lead compound for further studies. In order to improve the drug-like properties and to find a plausible bioactive conformation, a set of rigidified and methylated dipeptides of different stereochemistry, and analogs with reduced peptide character, were synthesized and evaluated regarding binding, metabolic stability and absorption. Small SP1–7 analogs with retained affinity and substantially improved permeability and metabolic stability were identified. Beside peptide chemistry the synthetic work included the development of a fast and convenient microwave-assisted protocol for direct arylation of imidazoles. Furthermore, microwave-assisted aminocarbonylation using Mo(CO)6 as a solid carbon monoxide source was investigated in the synthesis of MAP amides and for coupling of imidazoles with amino acids. In a future perspective the present findings, together with the fact that some of the SP1–7 analogs discovered herein have been shown to reproduce the biological effects of SP1-7 in animal studies related to neuropathic pain and opioid dependence, can ultimately have an impact on drug discovery in these two areas.