Thesis (MComm)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: New products are indispensable to the growth of the modem business enterprise. Increased global and local competition, better informed consumers, rapidly changing technology and the short life span of products are typical of the reasons why it is necessary to develop new products. Traditionally new product development took place in accordance with a rigid new product development process where a next phase was dependent on the completion of preceding phases. The increased pressure to produce new products in shorter time spans has led to the development and application of less streamlined and rigid processes for the development of new products. The pharmaceutical industry has certain unique characteristics important for new product development. It spends more than five times than the average of all industries on research and development. New product development in the pharmaceutical industry largely depends on the discovery of new clinical entities and the development process is furthermore also highly regulated by governments. The focus of product evaluation in the pharmaceutical industry has also undergone a major shift. Traditionally the industry dealt with diseases which were defined broadly and as such the focus was on diseases and not individuals. The result was that consumer acceptance was virtually never evaluated. The shift is now to consumer acceptance because consumers become increasingly better informed and take part in decisions regarding their health and medical care. A further reason for the consumer focus lies in the genetic understanding of patients and this enable pharmaceutical companies to segment patients on the basis of pharmaco-genomic descriptions. The objectives of the study are twofold. In the first instance, the study assesses whether marketing practitioners in the South African pharmaceutical industry agree with the fundamental principles of new product development which are identified in academic literature. The responses from marketing personnel were obtained and analysed to establish their beliefs regarding new product development. The fundamental principles of new product development which form the focus of this study, were those that Calantone, Di Benedetto and Haggblom (1995) used in their research. The second objective of the study is to compare the findings in respect of the South African pharmaceutical industry with those of the study undertaken by Calantone, Di Benedetto and Haggblom in 1995. The purpose of the study is to establish whether the new product development principles taught in marketing management courses are relevant for the pharmaceutical industry. The method of investigation was divided into two sections, i.e. a literature overview and an empirical study. The literature study commenced with research on new product development in the South African Pharmaceutical Industry and other parts of the world. The Calantone, Di Benedetto and Haggblom (1995) questionnaire was also used in this study for data collection. The 91 pharmaceutical companies listed in Volume 34 of the 1999 MIMS Desk formed the population of the study. After contacting these companies a more accurate list was set up. After taking into account all the mergers that took place, 65 companies eventually constituted the population. Twenty nine of the questionnaires sent were returned and could be used. This represents a response rate of 44.6%. The organisations involved were responsible for 69.4% of the annual turnover of the total pharmaceutical industry in 1998 and their responses could therefore be regarded as representative of the pharmaceutical industry of South Africa. The questionnaire attended to the following principles of new product development: • Product innovation • New product development and launch tasks • Product diffusion • Interface between marketing, research and development • Organisational issues The information collected in respect of each pharmaceutical company was the following: • Annual turnover • Number of products manufactured and marketed • Number of employees • Number of new products launched during the past five years The findings of this study indicate that marketing staff in the South African pharmaceutical industry strongly agreed with those fundamental principles of new product development which were identified in academic literature. There was also a significant correlation between this study and the study undertaken by Calantone, Di Benedetto and Haggblom with respect to the percentage agreement on the various statements. It may thus be concluded that new product development principles taught in marketing managing courses are relevant for and are applied by marketing staff in the pharmaceutical industry in South Africa. / AFRIKAANSE OPSOMMING: Nuwe produkte is onontbeerlik vir die groei van die moderne sake-onderneming. 'n Toename in globale en lokale mededinging, beter ingeligte verbruikers, snel veranderende tegnologie en die kort lewensduur van produkte is tipies van die redes waarom dit belangrik is om nuwe produkte te ontwikkel. Tradisioneel het nuwe produk ontwikkeling volgens 'n rigiede nuwe produk ontwikkelingsproses plaasgevind waar 'n volgende fase afhanklik was van die voltooiing van voorafgaande fases. Die verhoogde druk om nuwe produkte in korter tye te vervaardig het tot die ontwikkeling en toepassing van minder stroombelynde en rigiede prosesse vir die ontwikkeling van nuwe produkte gelei. Die farmaseutiese bedryf het sekere unieke eienskappe wat belangrik is vir nuwe produk ontwikkeling. Die farmaseutiese bedryf bestee meer as vyfkeer die gemiddelde van alle bedrywe op navorsing en ontwikkeling. Nuwe produk ontwikkeling in die farmaseutiese bedryf is grootliks afhanklik van die ontdekking van nuwe kliniese entiteite en die ontwikkelingsproses word verder ook intensief gereguleer deur regerings. Die fokus van produkbeoordeling in die farmaseutiese bedryf het ook 'n verskuiwing ondergaan. Tradisioneel het die bedryf gehandel met siektes wat breed omskryf is en die fokus as sulks was op siektes en nie op individue nie. Die gevolg was dat verbruikersaanvaarding feitlik nooit beoordeel was nie. Die verskuiwing is nou na verbruikersaanvaarding omdat verbruikers toenemend beter ingelig word en deelneem aan besluite wat hulle gesondheid en mediese sorg raak. 'n Verdere rede vir die verbruikerfokus is daarin geleë dat pasiënte nou geneties verstaan kan word en dit maak vir farmaseutiese maatskappye moontlik om pasiënte op 'n farmakologies-genomiese basis te segmenteer. Die doelstellings van die studie is tweeledig. In die eerste instansie beoordeel die studie of bemarkingspersoneel werksaam in die die Suid-Afrikaanse farmaseutiese bedryf, saamstem met die fundamentele beginsels ten opsigte van nuwe produk ontwikkeling wat in die akademiese literatuur geïdentifiseer is. Die response van bemarkingpersoneel is verkry en ontleed om hulle oortuigings ten opsigte van nuwe produk ontwikkeling vas te stel. Die fundamentele beginsels van nuwe produk ontwikkeling wat die fokus van hierdie studie vorm, is dié wat Calantone, Di Benedetto en Haggblom (1995) in hulle navorsing gebruik het. Die tweede doelstelling van die studie is om die bevindings ten opsigte van die Suid-Afrikaanse farmaseutiese bedryf te vergelyk met dié van die studie onderneem deur Calantone, Di Benedetto en Haggblom in 1995. Die doel van die studie is om vas te stel of die nuwe produk ontwikkeling beginsels wat in bemarkingsbestuurkursusse onderrig word, relevant is vir die farmaseutiese bedryf. Die metode van ondersoek is onderverdeel in twee gedeeltes, naamlik 'n literatuuroorsig en 'n empiriese studie. Die literatuurstudie het begin met navorsing oor nuwe produk ontwikkeling in die Suid-Afrikaanse farmaseutiese bedryf en ander wêrelddele. Die Calantone, Di Benedetto en Haggblom (1995) vraelys is ook in hierdie studie vir die insameling van data gebruik. Die 91 farmaseutiese firmas wat in Volume 34 van die 1999 MIMS Desk gelys is, het die populasie van die studie gevorm. Na gesprekke met hierdie firmas en nadat alle samesmeltings in ag geneem is, is 'n meer akkurate lys opgestel en het die populasie uiteindelik uit 65 firmas bestaan. Nege en twintig van die vraelyste wat terugontvang is kon gebruik word. Hierdie verteenwoordig 'n responskoers van 44.6%. Die organisasies wat gereageer het was verantwoordelik vir 69.4% van die jaarlikse omset van die totale farmaseutiese bedryf in 1968 en die responses sou dus as verteenwoordigend van die farmaseutiese bedryf in Suid-Afrika beskou kon word. Die vraelys het aandag aan die volgende beginsels van nuweprodukontwikkeling gegee: • Nuweproduk ontwikkeling en loodstake • Produkdiffusie • Koppelvlakke tussen bemarking, navorsing en ontwikkeling • Organisatoriese kwessies Die inligting wat ten opsigte van elke farmaseutiese firma ingesamel is, is die volgende: • Jaarlikse omset • Aantal produkte vervaardig en bemark • Aantal werknemers • Aantal nuwe produkte wat gedurende die afgelope vyf jaar geloods is. Die bevindings van hierdie studie toon aan dat die bemarkingspersoneel in die Suid-Afrikaanse farmaseutiese bedryf sterk saamstem ten opsigte van die beginsels van nuwe produk ontwikkeling wat in die akademiese literatuur geïdentifiseer is. Daar bestaan ook 'n betekenisvolle korrelasie tussen hierdie studie en die Calantone, Di Benedetto en Haggblom studie ten opsigte van die persentasie wat saamgestem word oor die verskillende stellings. Die gevolgtrekking kan dus gemaak word dat die nuwe produk beginsels wat in bemarkingskursusse aangebied word, relevant is vir en toegepas word deur bemarkingspersoneel in die farmaseutiese bedryf in Suid- Afrika.

Despite significant advances in cancer treatment, clinical response remains suboptimal and there is a continued requirement for improved chemotherapeutics. The attrition rate for new therapies is high, due principally to lack of in vivo efficacy and poor pharmacodynamics. Consequently better systems are required to determine in vivo preclinical efficiency and drug-target interactions. Engineering of cancer cells to express fluorescent or bioluminescent proteins, either endogenously or under the control of specific gene promoters, and their detection by noninvasive optical imaging has the potential to improve preclinical drug development. In this study, a panel of colorectal cancer cell lines were engineered to express fluorescent and luminescent proteins either constitutively or under control of gene-promoters for the DNA damage response gene p53 or the cell cycle regulator p21, both important pharmacodynamic sensors. These cell lines were characterised for their potential as in vivo models of primary and metastatic tumour therapy response, several showing significant potential. In addition to the development of these models, this study also addressed the pharmacokinetics of different luciferase substrates and identified optimal temporal and dose characteristics for each. Furthermore, a new application for bioluminescent imaging was developed and validated for use in preclinical evaluation of vascular disrupting agents, a new generation of cancer therapeutic. This study demonstrates that despite the dynamic and variable nature of fluorescent and bioluminescent imaging, reproducible results can be obtained if appropriate precautions are taken. The models developed herein will expedite cancer drug development whilst reducing and refining the use of animals in research.

<p>A central aim in drug development is to ensure that the new drug is efficacious and safe in the intended patient population.</p><p>Mathematical models describing the pharmacokinetic-pharmacodynamic (PK-PD) properties of a drug are valuable to increase the knowledge about drug effects and disease and can be used to inform decisions. The aim of this thesis was to develop mechanism-based PK-PD-disease models for important safety and efficacy biomarkers used in anti-diabetic drug development. </p><p>Population PK, PK-PD and disease models were developed, based on data from clinical studies in subjects with varying degrees of renal function, non-diabetic subjects with insulin resistance and patients with type 2 diabetes mellitus (T2DM), receiving a peroxisome proliferator-activated receptor (PPAR) α/γ agonist, tesaglitazar.</p><p>The PK model showed that a decreased renal elimination of the metabolite in renally impaired subjects leads to increased levels of metabolite undergoing interconversion and subsequent accumulation of tesaglitazar. Tesaglitazar negatively affects the glomerular filtration rate (GFR), and since renal function affects tesaglitazar exposure, a PK-PD model was developed to simultaneously describe this interrelationship. The model and data showed that all patients had decreases in GFR, which were reversible when discontinuing treatment. </p><p>The PK-PD model described the interplay between fasting plasma glucose (FPG), glycosylated haemoglobin (HbA1c) and haemoglobin in T2DM patients. It provided a mechanistically plausible description of the release and aging of red blood cells (RBC), and the glucose dependent glycosylation of RBC to HbA1c. The PK-PD model for FPG and fasting insulin, incorporating components for β-cell mass, insulin sensitivity and impact of disease and drug treatment, realistically described the complex glucose homeostasis in the heterogeneous patient population. </p><p>The mechanism-based PK, PK-PD and disease models increase the understanding about T2DM and important biomarkers, and can be used to improve decision making in the development of future anti-diabetic drugs. </p>

Mining the human genome for therapeutic target(s) discovery promises novel outcome. Over half of the proteins in the human genome however, remain uncharacterized. These proteins offer a potential for new target(s) discovery for diverse diseases. Additional targets for cancer diagnosis and therapy are urgently needed to help move away from the cytotoxic era to a targeted therapy approach. Bioinformatics and proteomics approaches can be used to characterize novel sequences in the genome database to infer putative function. The hypothesis that the amino acid motifs and proteins domains of the uncharacterized proteins can be used as a starting point to predict putative function of these proteins provided the framework for the research discussed in this dissertation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Choy Wai Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 98-122). / Abstracts in English and Chinese. / Thesis committee --- p.i / Statement --- p.ii / Abstract --- p.iii / Acknowledgements --- p.vi / General abbreviations --- p.viii / Abbreviations of chemicals --- p.x / Table of contents --- p.xi / List of figures --- p.xv / List of tables --- p.xviii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Severe acute respiratory syndrome (SARS) - An overview --- p.1 / Chapter 1.1.1 --- Epidemiology of SARS --- p.1 / Chapter 1.1.2 --- Clinical presentation of SARS --- p.2 / Chapter 1.1.3 --- Diagnostic tests of SARS --- p.5 / Chapter 1.1.4 --- Treatment of SARS --- p.7 / Chapter 1.2 --- Severe acute respiratory syndrome coronavirus (SARS- CoV) --- p.8 / Chapter 1.2.1 --- The etiological agent of SARS --- p.8 / Chapter 1.2.2 --- The coronaviruses --- p.9 / Chapter 1.2.3 --- Genome of SARS-CoV --- p.11 / Chapter 1.3 --- Spike (S) glycoprotein of SARS-CoV --- p.14 / Chapter 1.3.1 --- Functions of SARS-CoV S glycoprotein --- p.15 / Chapter 1.3.2 --- Receptors for S glycoprotein of SARS-CoV --- p.17 / Chapter 1.4 --- 3C-like protease (3CLPro) of SARS-CoV --- p.20 / Chapter 1.4.1 --- Extensive proteolytic processing of SARS-CoV replicase polyproteins --- p.20 / Chapter 1.4.2 --- SARS-CoV 3CLPro --- p.21 / Chapter 1.4.3 --- Substrate specificity of SARS-CoV 3CLPro --- p.22 / Chapter 1.5 --- Combating SARS - Vaccine and drug development --- p.24 / Chapter 1.5.1 --- Vaccine development against SARS --- p.24 / Chapter 1.5.2 --- Drug development against SARS --- p.25 / Chapter 1.6 --- Project objectives of this thesis --- p.27 / Chapter 1.6.1 --- Synthetic Peptide Studies on SARS-CoV S glycoprotein --- p.27 / Chapter 1.6.2 --- Synthetic Peptide Studies on SARS-CoV 3CLPro --- p.28 / Chapter 2 --- Materials and Methods --- p.30 / Chapter 2.1 --- Synthetic peptide studies on SARS-CoV S glycoprotein --- p.30 / Chapter 2.1.1 --- Bioinformatics analyses of SARS-CoV S gly- coprotein --- p.30 / Chapter 2.1.2 --- Peptide design and molecular modeling --- p.32 / Chapter 2.1.3 --- Solid phase peptide synthesis (SPPS) --- p.33 / Chapter 2.1.4 --- Peptide conjugation --- p.35 / Chapter 2.1.5 --- Immunization in rabbits and monkeys --- p.36 / Chapter 2.1.6 --- ELISA analysis --- p.37 / Chapter 2.1.7 --- Immunofluorescent confocal microscopy --- p.39 / Chapter 2.2 --- Synthetic peptide studies on SARS-CoV 3CLpro --- p.40 / Chapter 2.2.1 --- Protein expression and purification --- p.40 / Chapter 2.2.2 --- Solid phase peptide synthesis (SPPS) --- p.41 / Chapter 2.2.3 --- Peptide cleavage assay --- p.44 / Chapter 2.2.4 --- Molecular docking --- p.46 / Chapter 3 --- Results --- p.48 / Chapter 3.1 --- Synthetic peptide studies on SARS-CoV S glycoprotein --- p.48 / Chapter 3.1.1 --- General features and structural analyses of the S glycoprotein --- p.48 / Chapter 3.1.2 --- Peptides design and synthesis --- p.53 / Chapter 3.1.3 --- ELISA analysis and immunofluorescent con- focal microscopy --- p.55 / Chapter 3.2 --- Synthetic peptide studies on SARS-CoV 3CLpro --- p.62 / Chapter 3.2.1 --- Substrate specificity of SARS-CoV 3CLPro . . --- p.62 / Chapter 3.2.2 --- Molecular docking of SARS-CoV 3CLPro and peptide substrates --- p.74 / Chapter 4 --- Discussion --- p.78 / Chapter 4.1 --- Synthetic peptide studies on SARS-CoV S glycoprotein --- p.78 / Chapter 4.1.1 --- Synthetic peptides elicited SARS-CoV specific antibodies --- p.78 / Chapter 4.1.2 --- Factors affecting the specificity and antigenic- ity of synthetic peptides --- p.80 / Chapter 4.1.3 --- Next step towards vaccine development --- p.83 / Chapter 4.1.4 --- A synthetic peptide-based approach --- p.84 / Chapter 4.2 --- Synthetic peptide studies on SARS-CoV 3CLpro --- p.86 / Chapter 4.2.1 --- A comprehensive overview of the substrate specificity of SARS-CoV 3CLpro --- p.87 / Chapter 4.2.2 --- Sequence comparison between SARS-CoV 3CLpro cleavage sites --- p.90 / Chapter 4.2.3 --- A rapid and high throughput approach to screen protease substrate specificity --- p.94 / Bibliography --- p.98

<p>This thesis describes the use of a new technology, the Cytosensor^® microphysiometer, in the in vitro evaluation of cytotoxic drugs, using the lymphoma cell line U-937 GTB and primary cultures of tumour cells from patients as model systems. The method was specifically applied to study the metabolic effects of the novel cyanoguanidine N-(6-(4-chlorophenoxy)hexyl)-N’-cyano-N’’-4-pyridylguanidine, CHS 828, currently in phase I/II clinical trials. </p><p>The Cytosensor^® measures metabolic effects as changes in the rate of extracellular acidification of cells exposed to a drug by perfusion. A number of standard cytotoxic drugs were found to produce typical and reproducible acidification response patterns during observation times up to 20 h. There seemed to be a relationship between a decrease in acidification and cytotoxicity, measured in the fluorometric microculture cytotoxicity assay (FMCA), after 20-24 h of continuous drug exposure.</p><p>In U-937 cells, CHS 828 induced a cytotoxic effect characterised by a steep concentration-response relationship followed by a plateau. After 24 h of incubation the DNA and protein synthesis were turned off. CHS 828 was found to produce a rapid and prolonged increase in extracellular acidification and lactate production similar to that of the structurally related mitochondrial inhibitor m-iodobenzylguanidine (MIBG). The CHS 828 induced acidification was observed in cell lines as well as in cells from various tumour types from patients and probably originates from increased glycolytic flux. The effects may be secondary to block of oxidative phosphorylation in the mitochondria, but the relevance of the early acidification is not clear. CHS 828 seemed to induce a late, at approximately 15 h, inhibition of the glycolysis followed by loss of ATP and subsequent cell death. After exposure to MIBG the loss of ATP and cell death occurred earlier and in parallel. The effects of CHS 828 were not found to resemble those of the structurally related polyamine biosynthesis inhibitor methylglyoxal-bis(guanyl-hydrazone) (MGBG). Thus, CHS 828 may represent a new and, thus, interesting mode of cytotoxic action worthwhile for further development.</p><p>In combinatory studies, a synergistic interaction was demonstrated between CHS 828 and the non-toxic drug amiloride. Additive-to-synergistic effects were also seen between CHS 828 and the bioreductive cytotoxic drug mitomycin C. In U-937 cells as well as in tumour cells from patients, CHS 828 demonstrated synergistic interactions in combination with melphalan and etoposide. </p><p>It is concluded that measurement in the Cytosensor^® microphysiometer of early cellular metabolic changes is a feasible and potentially valuable complement to more conventional methods used in the evaluation of anticancer agents. </p>

<p>During the last decades, chemotherapy with cytotoxic drugs has played a significant role in cancer therapy. It’s important to develop new anticancer drugs, and drug sensitivity testing in vitro can be used to find the right diagnosis for the newly developed substances.</p><p>The aim of this study was to investigate the cytotoxic activity of the new signal transduction modulators bortezomib, gefitinib and PKC412. The well-established substances cisplatin, cytarabine, doxorubicin and vincristin were investigated for comparison.</p><p>The activity of the cytotoxic drugs was analysed in human tumor samples from patients with ovarian carcinoma (n=16) and lymphoma (n=15) by using the Fluorometric Microculture Cytotoxicity Assay (FMCA). The testing of cellular drug resistance by FMCA was accomplished successfully in 33 out of the 34 samples (97%).</p><p>The results of this study indicated that the activity of cytotoxic drugs in tumor cells obtained from patients with ovarian carcinoma and lymphoma may be detected by the FMCA. It also suggested that bortezomib and gefitinib could represent promising agents for treatment of ovarian carcinoma and that PKC412 might be of less use for patients with this diagnose.</p>

<p>This thesis examines the transport of exogenous molecules across the blood-brain barrier (BBB), focusing on active efflux, using positron emission tomography (PET), computer simulation and modelling. P-glycoprotein (P-gp) inhibition was studied using [¹¹C]verapamil and [¹¹C]hydroxyurea was investigated as a new marker for active efflux transport. Simulations were carried out to explore the importance of the efflux transporter location in the BBB. Brain concentrations of [¹¹C]verapamil, [¹¹C]GR205171 and [¹⁸F]altanserin were compared in various laboratory animal species and in humans.</p><p>A central aspect of the studies has been the novel combination of dynamic PET imaging of the brain pharmacokinetics of a labelled drug, administered through an exponential infusion scheme allowing time-resolved consequence analysis of P-gp inhibition, and mathematical modelling of the obtained data. The methods are applicable to drugs under development and can be used not only in rodents but also in higher species, potentially even in humans, to investigate the effects of P-gp or other transporters on drug uptake in the brain.</p><p>The inhibition of P-gp by cyclosporin A (CsA) and the subsequent change in brain concentrations of [¹¹C]verapamil occurred rapidly in the sense that [¹¹C]verapamil uptake increased rapidly after CsA administration but also in the sense that the increased uptake was rapidly reversible. The P-gp inhibition was best described by an inhibitory indirect effect model in which CsA decreased the transport of [¹¹C]verapamil out of the brain. The model indicated that approximately 90% of the transport of [¹¹C]verapamil was P-gp-mediated. The low brain concentrations of [¹¹C]hydroxyurea appeared to be a result of slow transport across the BBB rather than active efflux. This exemplifies why the extent and the rate of brain uptake should be approached as two separate phenomena. The brain-to-plasma concentration ratios for the three studied radiotracers differed about 10-fold be-tween species, with lower concentrations in rodents than in humans, monkeys and pigs. The increase in brain concentrations after P-gp inhibition was somewhat greater in rats than in the other species. </p><p>The findings demonstrate a need to include the dynamics of efflux inhibition in the experimental design and stress the importance of the choice of species in preclinical studies of new drug candidates. </p>

3-bromophenyl 6-acetoxymethyl-2-oxo-2H-1-benzopyran-3-carboxylate (IK9) was recently reported to be a potent inhibitor of cancer cell invasion and angiogenesis. It markedly reduced in vitro invasion of human HT1080 fibrosarcoma cells through collagen-coated porous membranes (Boyden chamber assay) and in vivo tumour growth in athymic nude mice. It was furthermore able to decrease angiogenesis ex vivo in a rat aortic ring assay and in vivo in a choroidal neovascularisation mice model. It nevertheless presents some water solubility and stability problems, which should be taken into account for further investigations. In the first part of the project, we synthesized original IK9 derivatives, modulated at the 3- and 6-positions, by introducing functional groups able to improve water solubility and metabolic stability. Their anti-invasive potency was screened in the Boyden chamber assay and the generated results highlighted some structure-activity relationships. A second part of the project was devoted to the elucidation of the actually unknown mechanism of action of IK9. Anti-invasive or anti-proliferative effects against endothelial cells, main actors of the angiogenic process, were not emphasised. We showed that IK9 acts likely not as an inhibitor of receptor tyrosine kinases (EGFR, PDGFR and VEGFR). The compound generates a weak decrease of mRNA coding for metalloproteinases (MMPs) 2 and 9, and on the other hand a substantial diminution of MMP 2 and 9 secretions by HT1080 fibrosarcoma cells. In conclusion, the consideration of anti-invasive properties together with the worked out solubility and stability profiles highlights several series, notably 6-hydroxycoumarins, 6-hydroxymethylcoumarins and coumarin-3-sulfonamides, whose interest as potential successors to IK9 is undeniable. Le 6-acétoxyméthyl-2-oxo-2H-1-benzopyrane-3-carboxylate de 3-bromophényle (IK9) est un dérivé coumarinique décrit comme inhibiteur puissant de linvasion tumorale et de langiogenèse. Il inhibe linvasion des cellules HT1080 de fibrosarcome humain in vitro à travers une membrane poreuse recouverte dune couche de collagène (test en « chambres de Boyden ») et la croissance tumorale in vivo chez des souris athymiques nues. Il est par ailleurs capable de bloquer langiogenèse, à la fois dans un modèle ex vivo danneaux daorte de rats et dans un modèle in vivo de néovascularisation choroïdale chez la souris. Il présente pour autant une problématique dhydrosolubilité et de stabilité, dont il faudra tenir compte lors dinvestigations futures. Dans une première partie du projet, nous avons synthétisé des dérivés originaux de lIK9, modulés en position 3 et 6 du noyau coumarinique, en introduisant des fonctions susceptibles daugmenter lhydrosolubilité et la stabilité métabolique des molécules obtenues. Leur pouvoir anti-invasif a été évalué dans le test en « chambres de Boyden », ce qui nous a permis de mettre en évidence différentes relations structure-activité. Une deuxième partie du projet fut consacrée à létude du mécanisme daction de lIK9, qui est non identifié jusquà présent. Un effet anti-invasif ou anti-prolifératif envers les cellules endothéliales, actrices principales du processus dangiogenèse, na pu être observé. LIK9 nagit vraisemblablement pas en tant quinhibiteur de plusieurs récepteurs de type tyrosine kinase (EGFR, PDGFR et VEGFR). Le composé engendre une légère baisse de lexpression de lARNm codant pour les métalloprotéases matricielles (MMPs) 2 et 9 mais par contre entraîne une diminution substantielle de la sécrétion des MMPs 2 et 9 par les cellules HT1080 de fibrosarcome humain. En conclusion, la prise en compte simultanée de lactivité anti-invasive, de lhydrosolubilité et de la stabilité met en avant plusieurs séries de dérivés, notamment des 6-hydroxycoumarines, des 6-hydroxyméthylcoumarines et des coumarine-3-sulfonamides, dont lintérêt en tant que successeurs potentiels de lIK9 est indéniable.

This thesis examines the transport of exogenous molecules across the blood-brain barrier (BBB), focusing on active efflux, using positron emission tomography (PET), computer simulation and modelling. P-glycoprotein (P-gp) inhibition was studied using [11C]verapamil and [11C]hydroxyurea was investigated as a new marker for active efflux transport. Simulations were carried out to explore the importance of the efflux transporter location in the BBB. Brain concentrations of [11C]verapamil, [11C]GR205171 and [18F]altanserin were compared in various laboratory animal species and in humans. A central aspect of the studies has been the novel combination of dynamic PET imaging of the brain pharmacokinetics of a labelled drug, administered through an exponential infusion scheme allowing time-resolved consequence analysis of P-gp inhibition, and mathematical modelling of the obtained data. The methods are applicable to drugs under development and can be used not only in rodents but also in higher species, potentially even in humans, to investigate the effects of P-gp or other transporters on drug uptake in the brain. The inhibition of P-gp by cyclosporin A (CsA) and the subsequent change in brain concentrations of [11C]verapamil occurred rapidly in the sense that [11C]verapamil uptake increased rapidly after CsA administration but also in the sense that the increased uptake was rapidly reversible. The P-gp inhibition was best described by an inhibitory indirect effect model in which CsA decreased the transport of [11C]verapamil out of the brain. The model indicated that approximately 90% of the transport of [11C]verapamil was P-gp-mediated. The low brain concentrations of [11C]hydroxyurea appeared to be a result of slow transport across the BBB rather than active efflux. This exemplifies why the extent and the rate of brain uptake should be approached as two separate phenomena. The brain-to-plasma concentration ratios for the three studied radiotracers differed about 10-fold be-tween species, with lower concentrations in rodents than in humans, monkeys and pigs. The increase in brain concentrations after P-gp inhibition was somewhat greater in rats than in the other species. The findings demonstrate a need to include the dynamics of efflux inhibition in the experimental design and stress the importance of the choice of species in preclinical studies of new drug candidates.