Dissertations / Theses on the topic 'CYP3A4'
To see the other types of publications on this topic, follow the link: CYP3A4.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'CYP3A4.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sethabouppha, Benjabhorn. "Inter-Individual Variation in CYP3A4 and CYP3A5- Mediated Drug Metabolism." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492887.
Full textAbstract:
Cytochrome P450 enzymes, especially those of the CYP3A family, play a major role in the metabolism of many drugs.' Patient response to drugs metabolized by CYP3A4 and CYP3A5 varies considerably and part of this variability is due to genetic polymorphism ot the CYP3A5 enzyme. In this study, human liver microsomes (HLM) were prepared from a panel of 26 liver samples and total soluble protein was evaluated. The CYP3A5 and CYP3A4 protein contents were determined by Western blotting and metabolic studies of individual HLM were performed with three selected substrates, ALP, MDZ and TST using HPLC. Results from the 26 HLM preparations revealed a high variability in CYP3A4 (366.7-1.06 pmol/mg protein, 346 fold) and CYP3A5 (4.26 -0.14 pmol/mig protein, 30 fold) content. As might be expected, the two samples with the CYP3A5*l/*3 genotype expressed higher CYP3A5 protein level than the other 24 samples (CYP3A5*3/*3) indicating the consequence of the CYP3A5*1 allele on CYP3A5 protein expression.
2
Willrich, Maria Alice Vieira. "Efeitos de hipolipemiantes sobre a expressão de CYP3A4 e CYP3A5 in vitro e in vivo." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-12092012-150610/.
Full textAbstract:
Introdução: As CYP3A4 e CYP3A5 são enzimas do citocromo P450 responsáveis pela biotransformação de esteróides endógenos e vários fármacos, entre eles as estatinas. Polimorfismos nos genes CYP3A4 e CYP3A5 (CYP3A4*1B, CYP3A5*3C e CYP3A5*1D) foram associados com diferenças na resposta hipolipemiante de indivíduos tratados com atorvastatina e sinvastatina. Neste estudo foram avaliados os efeitos de hipolipemiantes sobre a expressão e a atividade de CYP3A4 e CYP3A5, em linhagens celulares HepG2 e Caco-2 e em CMSP de indivíduos hipercolesterolêmicos, e sua relação com variantes de CYP3A4 e CYP3A5. Métodos: Foram analisados 99 indivíduos normolipidêmicos (NL) e 139 hipercolesterolêmicos (HC). Os HC foram tratados com atorvastatina (10 mg/dia/4 semanas). A genotipagem das variantes CYP3A4*1B, CYP3A5*3C e CYP3A5*1D foi feita por PCR-RFLP ou sequenciamento. A análise da expressão de RNAm de CYP3A4 e CYP3A5 foi avaliada por PCR em tempo real quantitativo (PCRq). As proteínas totais de HepG2 foram avaliadas por Western Blotting. A atividade de CYP3A4 e CYP3A5 in vivo foi avaliada pela relação entre cortisol e seu metabólito, 6β-hidróxicortisol, na urina (razão 6βOH-cortisol/cortisol), por CLAE. Resultados: O perfil de expressão basal de RNAm de CYP3A4 e CYP3A5 é diferente entre HepG2 e Caco-2. Caco-2 expressa 31 vezes mais CYP3A4 e 122 vezes mais CYP3A5 que HepG2. Em células HepG2 tratadas por 12 h, a atorvastatina 20 µM aumentou a expressão de CYP3A4 em 10 vezes, em relação ao controle (p=0,006). Após 24 h de tratamento, atorvastatina (1-20 µM) aumentou a expressão de CYP3A4 em 5 a 8 vezes, nas HepG2 (p< 0,001). Para CYP3A5, a exposição por 12 h à atorvastatina 20 µM aumentou a expressão em 4 vezes em relação ao controle ( p<0,001). A exposição à sinvastatina 1,0 µM por 24 h aumentou a expressão de CYP3A4, em 2 vezes (p<0,01), em HepG2. Também se observou que, nesse tempo de tratamento, a sinvastatina (0,1 µM a 10 µM) aumentou a expressão de CYP3A5 em 2 a 4 vezes (p<0,05). A linhagem HepG2 apresenta alelos funcionais (CYP3A4*1A e CYP3A5*1A) em homozigose. A linhagem Caco-2 apresenta os alelos não funcionais CYP3A5*3C e CYP3A5*1D, em heterozigose. Também foi avaliada a expressão das proteínas CYP3A4 e CYP3A5 por Western Blotting, em células HepG2, após atorvastatina (0,1 a 20 µM) e sinvastatina (0,01 a 10 µM) por 12 e 24 h. O perfil de expressão das proteínas não diferiu com os tratamentos. Nas células mononucleares do sangue periférico (CMSP), a expressão de RNAm basal de CYP3A4 é cerca de 2,5 a 9,6 vezes maior que a expressão de CYP3A5 (p< 0,05). Observou-se correlação da expressão de CYP3A4 e CYP3A5 nessas células, antes (r2 = 0,22; p< 0,0001) e após o tratamento (r2 = 0,58; p<0,0001) com atorvastatina. A expressão basal de RNAm de CYP3A4 e CYP3A5 é maior nos indivíduos (NL) que nos indivíduos (HC) (p<0,05). A atorvastatina não influenciou a expressão de CYP3A4 e CYP3A5 em CMSP (p> 0,05). Os indivíduos NL apresentam atividade de CYP3A4 e CYP3A5 basal maior que os indivíduos HC- (p<0,0001). O tratamento com atorvastatina não alterou a atividade de CYP3A4 e CYP3A5 nos HC (p>0,05). As variantes gênicas estudadas (CYP3A4*1B, CYP3A5*3C e CYP3A5*1D) como grupos haplotípicos não afetaram a resposta ao tratamento, a expressão de RNAm ou a atividade de CYP3A4 e CYP3A5, embora o haplótipo AGT tenha expressão basal de RNAm de CYP3A5 menor que os portadores de haplótipos GAT e GAC (p<0,005). Conclusão: Os resultados deste trabalho nos permitem concluir que a atorvastatina e a sinvastatina, mas não a ezetimiba, influenciam a expressão de CYP3A4 e CYP3A5 in vitro, em linhagem derivada de hepatócitos (HepG2), e que este efeito não foi reproduzido em linhagem derivada de enterócitos (Caco-2). A expressão de CYP3A4 e CYP3A5 tem grande variabilidade interindividual, independente do grupo haplotípico de cada indivíduo, e que não é influenciada pela atorvastatina.Background: CYP3A4 and CYP3A5 are enzymes from the cytochrome P450 resposible for the biotransformation of endogenous steroids and several drugs, e.g. statins. Polymorphisms in CYP3A4 and CYP3A5 (CYP3A4*1B, CYP3A5*3C and CYP3A5*1D) have been associated with variation of lipid-lowering response in individuals treated with atorvastatin and simvastatin. In this study we evaluated the effect of hypolipemiants on expression and activity of CYP3A4 and CYP3A5, in HepG2 and Caco-2 cell lines as well as peripheral blood mononuclear cells (PBMC) in hypercholesterolemic individuals, and their relationship with CYP3A4 and CYP3A5 variants. Methods: We analyzed 99 normolipidemic individuals (NL) and 139 hypercholesterolemic (HC). HC subjects were treated with atorvastatin (HC, 10 mg/day/4 weeks). Analysis of CYP3A4*1B, CYP3A5*3C e CYP3A5*1D variants was performed with PCR-RFLP or sequencing assays and mRNA expression of CYP3A4 and CYP3A5 with Quantitative Real-time PCR (qRT-PCR) was performed . Total protein content was extracted from HepG2 for Western Blotting experiments. Activity of CYP3A4 and CYP3A5 in vivo was evaluated by 6βOH-cortisol and cortisol ratio in urine samples, by HPLC-UV method. Results: Baseline mRNA expression is different for HepG2 and Caco-2. Caco-2 expresses 31 times more CYP3A4 and 122 times more CYP3A5 than HepG2. In HepG2 cells treated for 12h, atorvastatin 20 µM increased CYP3A4 expression in 10 times, when compared to the control (p=0.006). After 24h treatment, atorvastatin (1-20 µM) increased CYP3A4 mRNA expression in 5 to 8 times, in HepG2 (p< 0.001). To CYP3A5, exposure for 12h to atorvastatin 20 µM increased expression in 4 times when compared to the control (p<0.001). Exposure to simvastatin 1.0 µM for 24 h increased CYP3A4 expression in 2 times, (p<0.01), in HepG2. With the 24h treatment,simvastatin (0.1 µM - 10 µM) CYP3A5 showed increased mRNA expression in 2 to 4 times (p<0.05). HepG2 cell line carries homozygous functional alleles (CYP3A4*1A e CYP3A5*1A). Caco-2 carries heterozygous CYP3A5*3C and CYP3A5*1D. We evaluated the protein expression of CYP3A4 and CYP3A5 with Western Blotting in HepG2 cells, after atorvastatin (0.1 - 20 µM) and simvastatin (0.01 - 10 µM) for 12 and 24 h. The proteins profile did not change with statins treatment. In PBMC, baseline mRNA expression of CYP3A4 is approximately 2.6 to 9.5 times higher than CYP3A5 (p< 0.05). There was a correlation in expression between CYP3A4 and CYP3A5, before (r2 = 0.22; p< 0.0001) and after treatment (r2 = 0.58; p<0.0001) with atorvastatin. Baseline mRNA expression of CYP3A4 and CYP3A5 is higher in (NL) than in (HC) (p<0.05). Atorvastatin treatment did not increase CYP3A4 and CYP3A5 mRNA in PBMC (p>0.05). CYP3A4/5 activity was higher in NL subjects than in HC (p<0.0001). Atorvastatin treatment did not affect CYP3A4/5 activity in HC (p>0.05). The studied variants CYP3A4*1B, CYP3A5*3C e CYP3A5*1D analyzed as a haplotype block did not affect response to treatment, mRNA expression or activity of CYP3A4 and CYP3A5. However, AGT haplotype showed lower CYP3A5 mRNA expression levels when compared to GAC and GAT haplotypes at baseline (p<0.05). Conclusion: The results of this study allow us to conclude that atorvastatin and simvastatin, but not ezetimibe, influence the expression of CYP3A4 and CYP3A5 mRNA in vitro in HepG2 cell line, but this effect was not reproduced in Caco-2 cell line or PBMC. CYP3A4 and CYP3A5 present great interindividual variability, despite the individual´s haplotype and is not influenced by atorvastatin.
3
Ciaccia, Antonio. "Investigation of the interindividual variability in hepatic cytochrome P450 CYP3A4, association with CYP3A4*1B." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0004/MQ46139.pdf.
Full text
4
Tomlinson, Emma Suzanne. "Dexamethasone as a probe for CYP3A4." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337128.
Full text
5
El-Sankary, Wafaa Mahmoud. "Regulation of the human CYP3A4 gene." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326904.
Full text
6
Al-Shakargi, Bilall. "Variationer i allelfrekvens hos cytokrom-generna;CYP3A4*1B, CYP3A5*3 och CYP2B6*6 mellan Uganda och Tanzania." Thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388608.
Full textAbstract:
1. Abstrakt:Bakgrund: Malaria är en av världens viktigaste infektionssjukdomar och det beräknas vara ca300 miljoner drabbade varje år, därför är metabolismen av läkemedel som används för attbehandla malaria såsom kinin och artemisinin värt att lägga fokus på. Cytokrom P450enzymerna har en viktig roll i metabolism av malarialäkemedel och dessa uppvisar variationinterindividuellt samt mellan olika populationer på grund av polymorfism.Syfte: Denna studie har fokuserat på att undersöka tre polymorfa gener (CYP3A4*1B,CYP3A5*3 och CYP2B6*6) hos både friska och malariasmittade barn i Uganda för attjämföra resultaten med en population i Mwanza, Tanzania. Dessa polymorfa alleler påverkarmetabolismen av artemisinin och kinin, vilket i sin tur kan förorsaka minskad/ökad ellermisslyckad klinisk effekt.Metod: Genotypning av individernas blodprov gällande dessa genvarianter undersöktesgenom laboratoriestudier med PCR som huvudsaklig metod. DNA sekvensering utfördes vidUppsala Genome Center.Resultat: Resultaten visade att allelfrekvensen i Mwanza för CYP3A4*1B var 78%respektive 16% för CYP3A5*3, medan de var 72 % respektive 50% hos populationen iUganda. Allelfrekvensen för CYP2B6*6 i Uganda var 72 % och 36 % i Mwanza, Tanzania.Sammanfattning: De flesta malariamediciner uppvisar skillnader i kinetik och dynamikvilket kräver terapeutisk läkemedelsmonitorering. Sammanfattningsvis finns det skillnaderoch variationer bland de studerade polymorfa CYP enzymer interindividuellt och mellanolikaetniska grupper.Resultatet av denna studie visade både små skillnader mellan de två studerade populationernamen även skillnader mellan individer i den studerade gruppen i Uganda.
7
Bombail, Vincent. "Transcriptional control of the human CYP3A4 gene." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/843500/.
Full textAbstract:
CYP3A4 is the most abundant P450 enzyme expressed in the human liver and it is responsible for the metabolism of approximately 50% of all clinically administrated drugs. The CYP3A4 gene is transcriptionally regulated by xenobiotics and previous work has demonstrated the first 300bp of proximal promoter to be the minimal requirement for such activation. Several nuclear receptors (CAR, SXR) have been shown to be involved in the induction of the CYP3A4 gene. The aim of this work was to further delineate the molecular basis of CYP3A4 gene expression. In vitro DNase I footprinting was carried out using HepG2 nuclear extracts to map the sites of DNA-protein interaction within the -301/+7 region of the CYP3A4 gene. Putative protein assignment for these sites using in silico analysis revealed the potential binding of transcription factors previously shown to be involved in the regulation of other CYP genes (Sp1, HNF3 and C/EBP?) at the identified protein-DNA interaction sites. These regulatory regions were then disrupted by mutagenesis and their functional effect assessed by transient transfections of reporter gene plasmids into HuH7 hepatoma cells. Statistically significant reductions of reporter gene expression were observed when putative C/EBPa and HNF sites were altered, in both the basal and rifampicin (SXR ligand) induced states. This finding suggests the involvement of proteins binding at these sites in the regulation of the CYP3A4 gene expression. An examination of the CYP3A4 promoter (-1056/+7) from 11 human DNA samples exhibiting a 14.3 fold variability in CYP3A mediated metabolism failed to show the presence of mutations. Protein-DNA interaction analysis were carried out within the newly identified CYP3A4*IE and CYP3A4*1F alleles as well as the CYP3A4 *1B allele. The results implicate the Spl transcription factor in the regulation of the CYP3A4 gene, albeit at a more distal binding site. The findings described in this thesis suggest a substantial involvement of transcription factors other than SXR/CAR in expression of CYP3A4. Because of the polymorphic expression of several liver- and hormone-dependent transcription factors their role in CYP3A4 regulation must be taken into account to understand drug-induction mechanisms and assess variability in inter-individual drug response.
8
Kluth, Dirk. "Vom Antioxidanz zum Genregulator : transkriptionelle Regulation von Phase I- und Phase II-Enzymen durch Vitamin E und antioxidative sekundäre Pflanzeninhaltsstoffe." Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2006/1006/.
Full textAbstract:
Nahrungsinhaltsstoffe sind im Organismus an Steuerungsprozessen und Stoffwechselvorgängen beteiligt, wobei die Mechanismen ihrer Wirkung noch nicht völlig aufgeklärt sind. Wie Vitamin E zeigen auch sekundäre Pflanzeninhaltsstoffe in Zellsystemen sowie in vivo eine Reihe biologischer Wirkungen, deren Erklärung jedoch häufig auf ihre antioxidative Eigenschaft reduziert wird. Ziel der Dissertation war es, den Einfluss von Vitamin E und anderen Pflanzeninhaltsstoffen (in Form von Pflanzenextrakten oder isolierten sekundären Pflanzeninhaltsstoffen, z.B. Polyphenole), die bisher alle hauptsächlich als Antioxidanz klassifiziert wurden, auf die transkriptionelle Regulation von Phase I- und Phase II-Enzymen zu untersuchen. Dazu wurde die Aktivierung des PXR (pregnane X receptor) und des Nrf2 (NF-E2-related factor-2) als zentrale Transkriptionsfaktoren der Phase I- bzw. Phase II-Enzyme getestet.
Der Einfluss von verschiedenen Vitamin E-Formen und antioxidativen Pflanzeninhaltsstoffen in Form von Reinsubstanzen (Curcumin, EGCG, Medox, Quercetin, Resveratrol und Sulforaphan) oder Pflanzenextrakten (aus Blaubeeren, Gewürznelken, Himbeeren, Nelkenpfeffer, Thymian oder Walnüssen) auf die Aktivierung von PXR und Nrf2 sowie des Promotors eines jeweiligen Zielgens (CYP3A4 bzw. GI-GPx) wurde in vitro mit Reportergenplasmiden untersucht. Es zeigte sich, dass sowohl Vitamin E-Formen als auch verschiedene sekundäre Pflanzeninhaltsstoffe PXR und/oder Nrf2 sowie die Promotoren der jeweiligen Zielgene CYP3A4 bzw. GI-GPx aktivieren. In einem Tierexperiment konnte diese genregulatorische Wirkung von Vitamin E auf die in vivo-Situation übertragen werden. In Lebern von Mäusen, deren Futter unterschiedliche Mengen von Vitamin E enthielt (Mangel-, Normal- und Überflussdiät), wurde eine direkte Korrelation zwischen der alpha-Tocopherol-Konzentration und der Cyp3a11 mRNA-Expression nachgewiesen (Cyp3a11 ist das murine Homolog zum humanen CYP3A4). Entgegen der in vitro-Situation hatte gamma-Tocotrienol in vivo einen nur kaum nachweisbaren Effekt auf die Expression der Cyp3a11 mRNA, induzierte aber die Expression der alpha-TTP mRNA. Es konnte gezeigt werden, dass Vitamin E und sekundäre Pflanzeninhaltsstoffe Phase I- und Phase II-Enzyme transkriptionell regulieren können.
Die Wirkungen des Vitamin E können sich allerdings nur entfalten, wenn die Vitamin E-Formen ausreichend vom Körper aufgenommen werden. Gegenstand der Dissertation waren daher auch Untersuchungen zur Bioverfügbarkeit (zelluläre Akkumulation und Metabolismus) verschiedener Vitamin E-Formen. Es konnte gezeigt werden, dass Unterschiede in der chemischen Struktur der Vitamin E-Formen deren zelluläre Akkumulation und Metabolisierung beeinflussen.
Unter Berücksichtigung der Ergebnisse der Dissertation lassen sich protektive Wirkungen von antioxidativen Nahrungsinhaltsstoffen auch unabhängig von ihren antioxidativen Eigenschaften über die Induktion zelleigener Schutzsysteme, einschließlich der Phase I- und Phase II-Enzyme, erklären. Die Induktion der zelleigenen Abwehr lässt sich auch als adaptive Antwort (sog. "adaptive response") des Organismus gegenüber zellschädigenden Ereignissen betrachten.
In the organism food compounds are involved in regulatory and metabolic processes although the mechanisms of their effects have not been completely elucidated yet. Like vitamin E, secondary plant compounds have diverse biological effects, both in cell systems as well as in vivo. However, the explanation thereof is often reduced to their antioxidative capacity. The aim of this thesis was to investigate the influence of vitamin E and other plant compounds (in form of plant extracts or isolated secondary plant compounds, e.g. polyphenols), which were up to now classified primarily as antioxidants, on the transcription of phase I- and phase II-enzymes. For this, the activation of central transcription factors of the phase I- or phase II enzymes, PXR (pregnane X receptor) and Nrf2 (NF-E2-related factor-2), was tested.
The influence of different vitamin E forms and antioxidative plant compounds in form of pure substances (curcumin, EGCG, Medox, quercetin, resveratrol, and sulforaphane) or plant extracts (from blueberries, clove, raspberries, allspice, thyme, or walnuts) on the activation of PXR and Nrf2 as well as on the promoter of a respective target gene (CYP3A4 or GI-GPx) was investigated in vitro by reporter gene assays. It appeared that vitamin E forms as well as different secondary plant compounds activate PXR and/or Nrf2 as well as the promoter of the respective target genes CYP3A4 and GI-GPx. The effects of vitamin E were confirmed in vivo by an animal experiment. In livers of mice whose diet contained different amounts of vitamin E (deficient, adequate and supra-nutritional), a direct correlation between alpha-tocopherol content and Cyp3a11 mRNA expression was shown (Cyp3a11 is the murine homolog to the human CYP3A4). In contrast to the in vitro observations, gamma-tocotrienol in vivo only had a small effect on the expression of Cyp3a11 mRNA. However, it induced the expression of alpha-TTP on mRNA level. It could be shown that vitamin E and secondary plant compounds can influence the transcriptional regulation of phase I- and/or phase II-enzymes.
However, these effects of vitamin E can only be seen if the vitamin E forms are taken up by the body sufficiently. Therefore, another aim of the thesis was to investigate the bioavailability of different vitamin E forms (i.e., cellular accumulation and metabolism). It could be shown that differences in the chemical structure of vitamin E forms influence their cellular accumulation and metabolism.
Regarding the results of this thesis, protective effects of antioxidative food compounds can be explained independent of their antioxidative properties by the induction of cellular protective systems, including phase I- and phase II-enzymes. The induction of cellular defence mechanism can also be considered as an adaptive response of the organism towards cell-damaging events.
9
Gratien-Debette, Marilyne. "Etude rétrospective de l'influence des polymorphismes génétiques de CYP3A4, CYP3A5 et ABCB1 des donneurs et des receveurs sur les effets des immunosuppresseurs en transplantation hépatique." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0032/document.
Full textAbstract:
La transplantation hépatique est une technique chirurgicale maîtrisée, mais le devenir à long terme du greffon et de l’hôte doit encore être amélioré. L’étude pharmacogénétique des inhibiteurs de la calcineurine (CNI) devrait permettre de comprendre la variabilité de leurs effets thérapeutiques et toxiques. Dans un premier temps, nous avons réalisé une revue de la littérature concernant la pharmacogénétique des CNI en greffe d’organe et surtout hépatique en particulier les trois polymorphismes les plus impliqués dans la pharmacocinétique des CNI (CYP3A4*22, CYP3A5*3 et ABCB1 exons 12, 21, 26) et leurs éventuelles associations avec le devenir clinique du patient. L’état actuel des connaissances valide l’intérêt du génotype CYP3A5*3 pour adapter au mieux la posologie précoce de tacrolimus seulement en greffe rénale. Dans un second temps, nous avons mené une étude de cohorte rétrospective visant à étudier la pertinence et l’intérêt des génotypes du donneur et du receveur d’organe mentionnés précédemment, intervenant dans le métabolisme (CYP3A4*22, CYP3A5*3) et le transport membranaire (ABCB1 exons 12, 21 et 26) de la cyclosporine et du tacrolimus en transplantation hépatique. 170 patients avec un suivi de plus de 10 ans en moyenne ont été inclus. Les principaux résultats montrent que : l’allèle CYP3A5 *1 du receveur était associé significativement à un risque plus élevé de perte de greffon à long terme comparé à l’allèle CYP3A5 *3 ; l’allèle TT de l’exon 12 d’ABCB1 du receveur était associé à un risque moins élevé de rejet chronique ; et l’exposition à des doses élevées de CNI, la valeur initiale de la fonction rénale et l’âge du receveur étaient également indépendamment associés au risque d’altération de la fonction rénale. La caractérisation de ces marqueurs pharmacogénétiques en transplantation hépatique pourrait permettre d’adapter les traitements immunosuppresseurs pour chaque patient transplanté. D’autres voies de recherche (pharmacogénétique de la voie calcineurine, biomarqueurs précoces des lésions du greffon, ...) seront nécessaires pour identifier un profil personnalisé pour chaque greffé afin d’adapter au mieux la stratégie thérapeutique à long termeLiver transplantation is now a well mastered surgery with standardized procedures, but the long-term clinical outcomes of the graft and the patient remain uncertain. The pharmacogenetic study of the calcineurin inhibitors (CNI) cyclosporine and tacrolimus should help to understand the variability of their pharmacokinetics and therapeutic or side effects. In the first part of this work, we reviewed the main pharmacogenetic studies of CNI in liver transplantation, focusing on the three polymorphisms mostly involved in CNI pharmacokinetics (CYP3A4*22, CYP3A5*3 et ABCB1 exons 12, 21, 26) and their possible associations with clinical outcomes. To date, the only pharmacogenetic test consensually recommended in organ transplantation is the CYP3A5*3 variant for a better selection of the initial tacrolimus dose in kidney transplantation. The second part of this work was a retrospective cohort study in liver transplantation to investigate the influence of the above mentioned donor’s and recipient’s genotypes, involved in the metabolism (CYP3A4*22, CYP3A5*3) and the membrane transport (ABCB1 exons 12, 21 and 26) of cyclosporine and tacrolimus. 170 patients were enrolled in this study with a mean follow-up of more than ten years. Our main results are that: the recipient CYP3A5*1 allele was associated with a higher risk of graft loss than the CYP3A5*3 allele; the recipient ABCB1 exon 12 TT genotype was associated with a lower risk of chronic rejection than the CC genotype; overexposure to CNI, initial renal function and recipient age were associated with a higher risk of post-transplantation renal dysfunction. No genetic factor was associated with patient survival, acute rejection, liver function tests, recurrence of viral or other initial liver disease, or nephrotoxicity. Prospective characterization of both recipient and donor CYP3A4, CYP3A5 and ABCB1 polymorphisms could help to optimize immunosuppressive therapy for each candidate to liver transplantation. Further studies (pharmacogenetics of calcineurin pathway, early biomarkers of graft dysfunction, ...), should help to define a personalized profile for each transplant patient in order to best adapt the immunosuppressive strategy on the long term
10
Nem, Dieudonné [Verfasser]. "In vivo and in vitro investigation of the tissue-specific activity of the human CYP3A4 and CYP3A5 promoters / Dieudonné Nem." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1019667125/34.
Full text
11
Williams, Janet Mari. "Drug regulation of the human cytochrome P450 gene, CYP3A4." Thesis, University of Surrey, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360946.
Full text
12
Varis, Tiina. "Studies on drug interactions between CYP3A4 inhibitors and glucocorticoids." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/varis/.
Full text
13
He, Lei. "THE IMPACT OF CYP3A4*22 AND CYP3A5*3 ON DEXAMETHASONE AND 6-HYDROXY-DEXAMETHASONE PHARMACOKINETICS IN PHASE 1/2 CANCER PATIENTS." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357152908.
Full text
14
Argudo, Ramírez Ana. "Evaluación de la relevancia clínica de diversas variantes de los genes CYP3A4, CYP3A5 y ABCB1 sobre ciclosporina y tacrolimus en trasplante hepático." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/399045.
Full textAbstract:
Ciclosporina y tacrolimus son la base de la terapia inmunosupresora en el trasplante hepático, ya que son fármacos imprescindibles para la prevención del rechazo del órgano trasplantado. Sin embargo, todavía está pendiente de explicar una gran parte de su variabilidad farmacocinética y farmacodinámica. Existen estudios que ponen de manifiesto una relación entre las características farmacocinéticas y farmacodinámicas de estos fármacos con algunas variantes de genes que codifican para enzimas y proteínas clave relacionadas con su metabolismo y transporte. No obstante, los resultados publicados hasta el momento son controvertidos, cuya inconsistencia general puede estar relacionada con los siguientes factores: variabilidad étnica, pequeño número de pacientes incluidos en los estudios, inespecificidad de los sistemas de medida empleados para la determinación de la concentración de estos fármacos en sangre, variación en el punto del tiempo en el que se obtienen los resultados, e impacto del genotipo del donante.
En el presente trabajo se han estudiado las variantes CYP3A4*1B (c.-392A>G), CYP3A4*22 (c.522-191C>T), CYP3A5*3 (c.6986A>G), y c.3435C>T y c.2677G>T del gen ABCB1. Se ha realizado minimizado las posibles variaciones debidas al diseño del estudio con el fin de ayudar a resolver parte de esta variabilidad y obtener resultados consistentes: incluyendo únicamente pacientes de la misma etnia y con un único inmunosupresor en monoterapia durante los tres primeros meses post-trasplante, realizando todas las medidas de la concentración de los fármacos inmunosupresores en sangre con el mismo sistema de medida, considerando el parámetro “ratio concentración dosis” en el estudio, empleando modelos estadísticos que tienen en cuenta la dependencia de los datos de un mismo individuo en el tiempo e incluyendo el genotipo tanto del receptor como del donante. Además se ha investigado el papel potencial de los genotipos, tanto a nivel individual como en combinación (haplotipos). También se ha evaluado la relevancia clínica de los hallazgos obtenidos, y se ha estudiado la influencia de dichas variantes genéticas sobre la eficacia clínica (incidencia de rechazo agudo) y sobre la seguridad (incidencia de aparición de los efectos adversos) en el paciente trasplantado hepático.
En nuestra población en estudio, mediante los métodos descritos, se han identificado y/o al menos corroborado algunas observaciones interesantes que merecen estudios más detallados (como la de requerimientos de dosis más altos para los receptores de un injerto portador de la variante *1 del gen CYP3A5).
En cuanto a la prevención de acontecimientos adversos, en ciclosporina parece interesante la influencia del alelo CYP3A4*1B en receptores sobre la neurotoxicidad, la combinación del alelo CYP3A4*1B en donantes con el genotipo 3435CC de ABCB1 en receptores sobre la hipertensión arterial. En tacrolimus el alelo CYP3A5*1 en receptores muestra relación con la nefrotoxicidad e hipertensión arterial, el alelo 3435T de ABCB1 en donantes con la diabetes mellitus y los alelos 2677A/T de ABCB1 en donantes con la neurotoxicidad. Podrían llevarse a cabo estudios prospectivos para verificar estos hallazgos, y corroborar la repercusión que tiene el conocimiento del genotipo.
En general, se pone de manifiesto la relevancia del genotipo del donante. Aunque éste supone un inconveniente debido a que no puede ser elegido, recomendamos generar un Banco de ADN tanto de los receptores como de los donantes (incluyéndolo en el consentimiento informado) para permitir el acceso fácil y rápido a este tipo de muestras para la realización de futuros estudios farmacogenéticos.
Posibles líneas de futuro serían: realizar este tipo de estudios pero midiendo la concentración de estos fármacos en el interior de los linfocitos; así como investigar la función que desempeña ABCB1 en linfocitos, en tejido hepático, tejido renal y en barrera hematoencefálica en relación a ciclosporina y tacrolimus, ya que parece tener un papel clave no sólo a nivel del intestino.Cyclosporine and tacrolimus are the basis for immunosuppressive therapy in liver transplantation: they are essential drugs for organ transplant rejection prevention. However, a large part of its pharmacokinetic and pharmacodynamic variability still needs to be explained. A number of studies show a relation between the pharmacokinetics and pharmacodynamics of these drugs with some variants of genes encoding key enzymes and proteins related to their metabolism and transport. Nevertheless, the results published so far are controversial. Their general inconsistency may be related to the following factors: ethnic variability, small number of patients included in the studies, lack of specificity measuring systems used for concentration determination of these drugs in blood, variation at the point in time where the results are obtained, and impact of donor genotype. In this work we have studied the following variants: CYP3A4*1B (C-392A>G), CYP3A4*22 (c.522-191C>T), CYP3A5*3 (c.6986A>G), and c.3435C>T and c.2677G>T from ABCB1 gene. We have minimized possible variations due to study design in order to help solve part of this variability and obtain consistent results. We have furthermore investigated the potential role of genotypes, both individually and in combination (haplotypes). Moreover, we have evaluated the clinical relevance of the findings, and we have also studied the influence of these genetic variants on clinical efficacy (incidence of acute rejection) and safety (incidence of occurrence of adverse effects) in the liver transplanted patient. In our study population, by the methods described, we have identified and/or at least confirmed some interesting observations that deserve more detailed studies (such as the requirement of higher doses for recipients of the CYP3A5*1 carriers graft). As regards the prevention of adverse events, in cyclosporine seems interesting the influence of CYP3A4*1B allele in receptors on neurotoxicity, the combination of CYP3A4*1B allele in donors with 3435CC ABCB1 recipients on hypertension. In tacrolimus the CYP3A5*1 allele in recipients shows relation to nephrotoxicity and hypertension, the 3435T ABCB1 allele in donors with diabetes mellitus and 2677A/T alleles of ABCB1 donors with neurotoxicity. Prospective studies could be conducted to verify these findings and corroborate the impact of the genotype knowledge. In general, it shows up the relevance of the donor genotype.
15
Wen, Bo. "Analysis of human CYP3A4 structure-function relationships using photoaffinity labels /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/8154.
Full text
16
Stoffels, Felix [Verfasser]. "Polymorphismen in der Promoter- und Enhancerregion von CYP3A4 / Felix Stoffels." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2009. http://d-nb.info/1023958678/34.
Full text
17
Nylén, Frank. "Development of a reporter gene assay for PXR mediated CYP3A4 induction." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-14804.
Full textAbstract:
PXR mediated elevation of CYP3A4 expression is a costly problem in drug development as well as a clinical problem due to clinically important drug interactions caused by the enzyme induction. CYP3A4 is responsible for the metabolism of more than 50% of the drugs commonly used today. Many of these, as well as other compounds e.g. in herbal medicines can induce transcription of CYP3A4 and thereby enhance the metabolism of other drugs, rendering them ineffective or more toxic. By using an in vitro assay for CYP3A4 induction, tests can be performed on candidate drugs early in development and thereby save time and resources since CYP3A4 inducers are eliminated from further development. A reporter gene assay was constructed by inserting three modules, which includes PXR binding sites isolated from the CYP3A4 sequence, in front of a luciferase gene. This construct was transfected together with PXR into HEK 293 cells. Induction was evoked by adding rifampicin, a known CYP3A4 inducer, to the medium. After lysis of the HEK cells and addition of luciferase substrate, luminescence intensity was recorded as a measure of induction. The construct worked and consistently showed induction by rifampicin, but could be further improved to yield higher sensitivity.
18
Ogg, Malcolm Stuart. "In vitro assessment of the regulation of the human CYP3A4 gene." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389058.
Full text
19
Rodrigues, Iara Sant'ana. "Análise das variantes polimórficas CYP1A1*2B, CYP1B1*2, CYP3A4*1B, GSTM1*0 e GSTT1*0 em pacientes portadores de carcinoma de próstata." Universidade Estadual de Londrina. IAPAR. EMBRAPA. Centro de Ciências Biológicas. Programa de Pós-Graduação em Genética e Biologia Molecular, 2009. http://www.bibliotecadigital.uel.br/document/?code=vtls000154651.
Full textAbstract:
O perfil de morbimortalidade por câncer de próstata tem se alterado nas ultimas décadas, configurando-se como um serio problema de saúde publica mundial. Esta neoplasia e uma doença associada com a idade, com pico de incidência por volta da sétima década de vida e se constitui na segunda causa de morte por câncer em homens. São múltiplos os fatores que contribuem para o seu desenvolvimento: dieta, suscetibilidade hereditária e alterações genéticas adquiridas. Um dos fenômenos relevantes na suscetibilidade herdada e a presença de variantes polimórficas em genes envolvidos no metabolismo de drogas, que pode aumentar, reduzir ou inativar as enzimas por eles codificadas, interferindo no metabolismo de carcinogenos e hormônios andrógenos. Para definir possiveis associações com o câncer de próstata, cinco variantes polimórficas (CYP1A1*2B, CYP1B1*2, CYP3A4*1B, GSTM1*0 e GSTT1*0) foram estudadas em 170 pacientes que passaram por prostatectomia radical com confirmação histopatológica da doença. Foram avaliados também 170 controles com níveis de PSA normais (<2ng/mL), pareados aos pacientes quanto a idade e hábitos tabagista e etilista. O DNA do sangue periférico foi analisado através de PCR-alelo especifica para os genes CYP1A1 e CYP1B1, PCR-RFLP para o gene CYP3A4 e PCR Multiplex para os genes GSTT1 e GSTM1. O calculo da OR (Odds ratio) e do intervalo de confiança (IC=95%) foi utilizado no estudo de associação e os testes do Qui-Quadrado, Fisher e Mann-Whitney na avaliação dos parâmetros histopatológicos. O estudo de associação caso-controle indicou ausência de associação positiva ou negativa para as seguintes variantes genéticas estudadas: CYP1A1*2B OR=1,03, IC 95%= 0,64-1,66; GSTM1*0 OR= 0,64, IC 95%=0,42-0,98; GSTT1*0 OR= 1,03, IC 95%=0,64-1,66. A analise estatistica apontou para uma associação positiva significativa das variantes CYP1B1*2 (OR=1,55, IC 95%=0,98-2,47) e CYP3A4*1B (OR=1,51, IC 95%=0,97-2,37) para o câncer de próstata, estando os resultados no limite da significância. A análise combinada dos genótipos mostrou associação positiva significativa para as combinações das variantes CYP1A1*2B, CYP1B1*2 e CYP3A4*1B (OR=2,55, IC 95%=1,08-5,99). A analise dos parâmetros histopatológicos com os genótipos de suscetibilidade não detectou diferenças estatisticamente significativas, exceto em relação a variante CYP1A1*2B para invasão perineural (p=0,0382), a variante GSTT1*O isoladamente (p=0,0295) e em combinação com a variante GSTM1*O (p=0,0251) e a combinação dessas duas variantes de fase II com a variante CYP3A4*1B (p=0,0291), mostraram estatisticamente significativas para grau histológico. Nossos resultados indicaram que algumas variantes polimórficas analisadas isoladamente ou em combinação podem influenciar no desenvolvimento e na progressão do câncer de próstata.The profile of morbidity and mortality for prostate cancer has changed in recent decades, and become a serious public health problem worldwide. This cancer is a disease associated with age, with peak incidence around the seventh decade of life and is the second cause of cancer deaths in men. There are many factors that contribute to its development: diet, inherited susceptibility and acquired genetic changes. One of the relevant phenomena of the inherited susceptibility is the presence of polymorphic variants in genes involved in drugs metabolism that may increase, reduce or inactivate the enzymes encoded by them, interfering with the metabolism of carcinogens and hormone androgen. To determine possible associations with prostate cancer, five polymorphic variants (CYP1A1*2B, CYP1B1*2, CYP3A4*1B, GSTM1*0 and GSTT1*0) were studied in 170 patients who underwent radical prostatectomy with histopathological confirmation of the disease. We also evaluated 170 controls with normal PSA levels (<2ng/mL), matched to patients in age and smoking and alcohol habits. The DNA from peripheral blood was analyzed by PCRallele specific for the CYP1A1 and CYP1B1 genes, PCR-RFLP for the CYP3A4 gene and Multiplex-PCR for the genes GSTM1 and GSTT1. The OR (odds ratio) and confidence interval (CI = 95%) was used in the study of association and the Chi-square, Fisher and Mann-Whitney tests for the evaluation of histopathological parameters. The association case-control study showed absence of positive or negative association for the following studied genetic variants: CYP1A1*2B - OR = 1.03, 95% CI = 0,64-1,66; GSTM1*0 - OR = 0.64, 95% CI = 0 ,42-0, 98; GSTT1*0 - OR = 1.03, 95% CI = 0,64-1,66). The analysis statistics pointed with respect to significant a positive association of variants CYP1B1*2 (OR=1,55, IC 95%=0,98-2,47) and CYP3A4*1B (OR=1,51, IC 95%=0,97-2,37) for the prostate cancer, being the results in the limit of the significance. The combined analysis of genotypes showed significant positive association for the combinations of variants CYP1A1*2B, CYP1B1*2 and CYP3A4*1B (OR=2,55, IC 95%=1,08-5,99). The analysis of histopathological parameters did not detect statistically significant differences, except in relation variant CYP1A1*2B for perineural invasion (p=0,0382), variant GSTT1*O separately (p=0,0295) and in combination with variant GSTM1*O (p=0,0251) and the combination of these two variants of phase II with variant CYP3A4*1B (p=0,0291), had shown statistical significant for histologic degree. Our results had indicated that some separately analyzed polimorfic variants or in combination can influence in the development and the progression of the prostate cancer.
20
Xu, Yang. "Regulation of intestinal CYP3A4 expression and metabolism of 1Alpha, 25-Dihydroxyvitamin D3 /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/7933.
Full text
21
Burt, Howard James. "In Vitro Assessment and Prediction of Time-Dependent CYP3A4 Drug-Drug Interactions." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503677.
Full text
22
Lilja, Jari. "Effects of grapefruit juice on the pharmacokinetics of selected CYP3A4 substrate drugs." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/lilja/.
Full text
23
Madani, Soraya. "The role of CYP2D6 and CYP3A4 in first-pass intestinal drug metabolism /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/7942.
Full text
24
Creemer, O. "Genomic variation in CYP3A4 : type, frequencies and potential implications for pharmacogenetic understanding." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1348138/.
Full textAbstract:
The human cytochrome P450 3A subfamily metabolises endogenous substances and approximately half of all currently available drugs. There is marked inter-individual variation in hepatic expression of the major adult isoform, CYP3A4; the genetic component of this variability is estimated at 60-90% and, as yet, remains largely uncharacterised. Elucidation of genetic factors determining CYP3A4 activity would permit personalised dose-adjustment in therapies with CYP3A4 drug substrates. CYP3A4 genomic variation within the 5’ regulatory region, 3’ UTR, exons and regions of flanking adjacent introns was characterised by sequencing 752 chromosomes from five Ethiopian ethnic groups supplemented by sequencing data from The 1000 Genomes Project. Considerable novel variation was found within Ethiopia. CYP3A4 variants were identified that will form the foundations for future in vitro and in vivo work to determine the functional impact of variation on CYP3A4 expression/activity in vivo. Evidence of purifying selection was observed and genomic variation was consistent with the hypothesis that, within humans, the expression of CYP3A4 is essential to the maintenance of life. Conversely, regulatory region variation revealed the potential for considerable ethnic variation in the amount of protein expressed. Adult expression of the foetal isoform, CYP3A7, is associated with significantly altered levels of steroid hormones and may impact drug metabolism. A promoter variant, CYP3A7*1C, associated with adult expression of CYP3A7 was found at high frequency among populations of North Africa. Significant linkage disequilibrium was observed between CYP3A5*3 and CYP3A7*1C indicating that, within the populations studied, adult expression of CYP3A7 is likely to be accompanied by reduced/null expression of CYP3A5.
25
Hamzeiy, Hossein. "Identification and functional analysis of inherited variation in the CYP3A4 gene regulatory region." Thesis, University of Surrey, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248064.
Full text
26
Silva, Flávia Cristina da. "Desenvolvimento de modelos de QSAR para identificação de substratos e inibidores de CYP3A4." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5266.
Full textAbstract:
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-23T13:23:39Z
No. of bitstreams: 2
Dissertação - Flávia Cristina da Silva - 2015.pdf: 1680001 bytes, checksum: 3d5116e971ca03d4464ee6b64ab4a913 (MD5)
license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-23T13:26:06Z (GMT) No. of bitstreams: 2 Dissertação - Flávia Cristina da Silva - 2015.pdf: 1680001 bytes, checksum: 3d5116e971ca03d4464ee6b64ab4a913 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Made available in DSpace on 2016-02-23T13:26:06Z (GMT). No. of bitstreams: 2 Dissertação - Flávia Cristina da Silva - 2015.pdf: 1680001 bytes, checksum: 3d5116e971ca03d4464ee6b64ab4a913 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-26
The discovery and development of drugs consist of a complex process, requiring the integration of various strategic areas such as knowledge, innovation, technology, management and high investments in Research, Development and Innovation (RD&I). No drug can be approved for use in humans without first go through extensive studies aimed at ensuring its effectiveness and safety. On the other hand, a drug that inhibits the activity of a metabolic enzyme cytochrome P450 family (CYP450) can affect the pharmacokinetics of other drugs, resulting in drug-drug interactions (DDIs), which potentially lead to side effects and toxic effects. The main oxidative enzymes responsible for drug metabolism have as main representatives CYP450 superfamily, wherein the CYP3A4 isoform is the most important because it is responsible for metabolizing approximately 50% of the drugs on the market. Several computational methods have been developed as a strategy to predict human metabolism in the early stages of research and development of drugs. In silico models of metabolism have advantages such as faster, lower cost and ease of operation when compared to traditional models in vitro and in vivo. The work aimed mainly at the development of Quantitative Relations between models chemical structure and activity / property (QSAR / QSPR) robust and predictive, to identify CYP3A4 substrates and inhibitors. To this were collected, integrated and prepared larger data sets available in the literature substrates and inhibitors of CYP3A4. Several QSAR models were generated and validated for both properties using a workflow that contemplated carefully the recommendations of the Organization for Economic Co-operation Development (OECD). The combination of different descriptors and machine learning methods have led to obtain robust and predictive QSAR models, with correct classification rate (CCR) ranging from 0.65 to 0.83 and 0.69 to 0.89 of coverage, showing a statistically significant values for classification of compounds with high accuracy whether or not substrates of CYP3A4 substrates. The binary Morgan RFgenerated model to classify compounds inhibitors and non-inhibitors also proved highly robust and predictive with sensitivity values of 0.77 and accuracy of 0.76, and the Morgan-RF model multiclass obtained values of 0.68 sensitivity and 0.69 for accuracy. The map of predicted probability proved useful as it could encode major structural fragments to classify compounds inhibitors or not CYP3A4 inhibitors. In conclusion, have been developed and validated many QSAR to predict the interaction with the CYP450 enzyme that may be useful in the early stages of the development of new drugs. The next step is the online availability of the models obtained in LabMol server (http://labmol.farmacia.ufg.br).
A descoberta e o desenvolvimento de fármacos consistem um processo complexo, sendo necessária a integração de várias áreas estratégicas como conhecimento, inovação, tecnologia, gerenciamento e altos investimentos em Pesquisa, Desenvolvimento e Inovação (PD&I). Nenhum fármaco pode ser aprovado para uso em humanos sem que antes passe por extensivos estudos que visem garantir sua eficácia e segurança. Um fármaco que inibe a atividade metabólica de uma enzima da família citocromo P450 (CYP450), pode afetar a farmacocinética de outros fármacos, resultando em interações fármaco-fármaco (DDIs), que podem conduzir potencialmente a efeitos colaterais e tóxicos. As principais enzimas oxidativas responsáveis pelo metabolismo de fármacos possuem como principais representantes a superfamília CYP450, em que a isoforma CYP3A4 é a mais importante, pois é responsável por metabolizar aproximadamente 50 % dos fármacos disponíveis no mercado. Diversos métodos computacionais têm sido desenvolvidos como estratégia para predizer o metabolismo humano nos primeiros estágios de pesquisa e desenvolvimento de fármacos. Modelos in silico do metabolismo apresentam vantagens como maior rapidez, menor custo e maior facilidade de operação, quando comparados aos modelos tradicionais in vitro e in vivo. O trabalho teve como objetivo central o desenvolvimento de modelos de Relações Quantitativas entre estrutura química e atividade/propriedade (QSAR/QSPR) robustos e preditivos, visando identificar substratos e inibidores de CYP3A4. Para isso, foram compilados, integrados e preparados os maiores conjuntos de dados disponíveis na literatura de substratos e inibidores de CYP3A4. Vários modelos de QSAR foram gerados e validados para ambas as propriedades usando um fluxo de trabalho que contemplou criteriosamente as recomendações da Organization for Economic Co-operation Development (OECD). A combinação de diferentes descritores e métodos de aprendizado de máquina levaram a obtenção de modelos QSAR robustos e consistentes, com taxa de classificação correta (CCR) que variam entre 0,65-0,83 e cobertura de 0,69-0,89,demonstrando valores estatisticamente significativos para classificação com alta precisão de compostos em substratos ou não substratos de CYP3A4. O modelo Morgan-RF binário gerado para classificar compostos em inibidores e não inibidores se mostraram também altamente robusto e preditivo com valores de sensibilidade de 0,77 e acurácia de 0,76, e o modelo Morgan-RF multiclasse obteve valores de 0,68 para sensibilidade e 0,69 para acurácia. O mapa de probabilidade predita se mostrou útil, pois conseguiu codificar fragmentos estruturais importantes para classificar compostos em inibidores ou não inibidores de CYP3A4. Como conclusões foram desenvolvidos e validados diversos modelos de QSAR para prever a interação com a enzima CYP450 que podem ser úteis nos estágios iniciais do desenvolvimento de novos fármacos. O próximo passo será a disponibilização online dos modelos obtidos no servidor do LabMol (http://labmol.farmacia.ufg.br).
27
Thörn, Mari. "Qualitative and Quantitative Assessment of Cytochromes P450 mRNA in Human : Studies in the Liver, Blood and Gastrointestinal Mucosa." Doctoral thesis, Uppsala University, Department of Medical Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5786.
Full textAbstract:
Drugs and other foreign compounds must often be metabolised before they can be excreted from the body. One enzyme system that is responsible for this is the cytochrome P450 gene family (CYP). In this thesis, new sensitive molecular techniques have been used to study the human gene expression of some CYP enzymes, as well as the P-glycoprotein transporter (P-gp). The aim was to evaluate whether tissues other than the liver, e.g. the blood, could be used to assess an individual's drug metabolic capacity. Another aim was to investigate the gene expression in relation to the liver transplant process and a third aim was to evaluate the expression in gastrointestinal mucosa in both normal and inflamed mucosa.
We evaluated the CYP gene expression in paired specimens of liver and blood but found no correlation in the expression patterns of these two tissues. Instead, we found the opposite pattern, where, for example, CYP1B1 had the highest expression in the blood but the lowest in the liver and CYP2E1 was the enzyme with the highest expression in the liver. In an investigation of the expression of four different CYP enzymes and P-gp in liver transplants before and during the first year after transplantation, we found that the levels of all the CYP enzymes but not P-gp increased with time. We also found that the expression of CYP3A4 was inversely related to the normalised plasma levels of the immunosuppressive drugs cyclosporine and tacrolimus.
In the gastrointestinal tract, CYP2E1 was the enzyme with the highest mRNA expression compared with CYP3A4, CYP3A5 and the transporter P-gp. CYP3A4 has its highest expression in the duodenum compared with the expression in the stomach and the colon. CYP3A5 is expressed at a higher level than CYP3A4 in the colon. P-gp expression levels increase through the gastrointestinal tract to the left colon. Gene expression levels of CYP2E1 and CYP3A4 decrease in severely inflamed rectal mucosa.
In conclusion, this is a sensitive method for studying gene activity in a clinical situation, even though at this point we are not able to use blood or gastrointestinal mucosa as “surrogate” tissue to estimate an individual’s drug metabolic capacity. The studies in liver transplants and gastrointestinal mucosa are unique in that the gene expression is investigated during a clinical course of events.
28
Falconer, Stuart John. "Tacrolimus pharmacogenomics in abdominal solid organ transplantation." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31355.
Full textAbstract:
Background: Abdominal solid organ transplantation has evolved from an experimental procedure to a well-established therapy within a few decades. This success is largely due to the introduction of calcineurin inhibitor immunosuppression. Tacrolimus is the most widely used calcineurin inhibitor but has a narrow therapeutic range which requires close drug monitoring to prevent both toxicity and inadequate immunosuppression. Previous studies in renal transplantation have shown that genetic polymorphisms, CYP3A5, CYP3A4*22 and ABCB1 can influence the bioavailability and pharmacokinetics of tacrolimus. These polymorphisms are closely linked to ethnicity and have never been studied in a Scottish population before. Additionally, increasing evidence suggests that high variability of tacrolimus is linked to increased graft loss in kidney transplant patients. Methods: 5889 subjects were genotyped for the genetic polymorphisms CYP3A5 A > G allele transition, CYP3A4*22 C > T and ABCB1 C > T transition. This included 4899 healthy individuals from Generation Scotland bio-resource and 990 patients who underwent renal, liver, or simultaneous pancreas kidney transplants or were organ donors. Tacrolimus dose, trough level and renal function were measured at 11 time points from date of transplant up to and including 12 months post-transplant. Clinical data including episodes of acute rejection, graft and patient survival were compared between the different genotypes. Separate analyses were undertaken for kidney, SPK transplants, as well as liver transplants, the latter looking at recipient and liver donor genotype. A separate cohort of 103 renal transplant patients converted from twice-daily to once-daily tacrolimus had their tacrolimus variability calculated and compared with graft survival. Results: The distribution of the 3 different genotypes of CYP3A5, CYP3A4*22 and ABCB1 were comparable with other Caucasian populations studied previously. In renal transplant recipient expression of the A allele (GA/AA) led to significantly increased dose requirements of tacrolimus and initially lower tacrolimus trough levels. The different genotypes of ABCB1 had no effect. Expression of a CYP3A4*22 T allele trended towards a lower tacrolimus dose requirement but this was not significant. There was no difference in renal function, graft survival or patient survival with any of the polymorphisms. SPK patients had comparable results. In the liver transplant patients, the donor genotype had a greater influence than the recipient one. The donors with CYP3A5 A allele expression had significantly higher tacrolimus dose requirements and lower initial tacrolimus levels. This was apparent to a lesser extent with the recipient expression of CYP3A5 and did not reach statistical significance at all time points. There was no significant difference in tacrolimus dose requirements or level with either donor or recipient expression of ABCB1 or CYP3A4*22. There was a significantly higher incidence of acute rejection in donor CYP3A5 A allele expressers of liver transplant patients in univariate and multivariate analysis. There was no significant different in acute rejection with ABCB1 or CYP3A4*22 genotype. No differences in graft or patient survival with either donor or recipient genotype of any of the 3 polymorphisms were noted. Conversion from twice-daily to once-daily tacrolimus in the first 12 months post-transplant reduced tacrolimus variability. Patients with high tacrolimus variability pre and post conversion had significantly greater graft loss than patients with low tacrolimus variability. Conclusion: CYP3A5 expression results in increased tacrolimus requirements to achieve adequate immunosuppression in renal transplant and SPK patients. Donor rather than recipient CYP3A5 expression is relevant for liver transplantation and dose requirements. There may be an association with donor CYP3A5 expression in liver transplant patients and acute rejection which needs further evaluation. ABCB1 and CYP3A4*22 do not appear to have a significant impact in any of the organ transplants. High tacrolimus variability is associated increased graft loss in renal transplant patients.
29
Pereira, Rui Salvador Pais. "Toranja: benefícios e riscos para a saúde." Bachelor's thesis, [s.n.], 2017. http://hdl.handle.net/10284/7553.
Full textAbstract:
Trabalho Complementar apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de licenciado em Ciências da NutriçãoInteração medicamentosa é um evento clínico em que os efeitos de um fármaco são alterados pelo uso concomitante ou anterior à administração de outro fármaco, alimento ou bebida. A toranja tem vindo a ser estudada pelo potencial da sua utilização no combate de doenças crónicas devido à sua atividade antioxidante, anti-inflamatória, anticancerígena, bem como anti aterosclerótica. No entanto, a toranja é um dos alimentos mais estudados pelo seu potencial de interações medicamentosas. Avaliar a importância terapêutica das interações entre os alimentos e os medicamentos é particularmente difícil, sendo estas interações principalmente de natureza farmacocinética e muito complexa. Deste modo, a ingestão de alimentos pode influenciar parâmetros como a absorção, distribuição, metabolização e eliminação de determinados fármacos, ou, por outro lado, não influenciar estes parâmetros. A toranja é um exemplo conhecido deste tipo de interações, uma vez que pode interferir com alguns fármacos e causar toxicidade severa. A naringina, a naringenina e as furanocumarinas são componentes presentes na toranja e que são responsáveis pela inibição do CYP3A4 originando assim as interações com os fármacos. Sabe-se que inúmeros fármacos interagem com o sumo da toranja. Muitos destes fármacos são prescritos para o tratamento de doenças comuns e são metabolizados pelo citocromo P450 3A4. A glicoproteína-P e os polipéptidos transporte de aniões orgânicos estão também envolvidos nas interações com os fármacos, uma vez que sofrem interações com os compostos polifenólicos presentes na toranja. Com o desenvolvimento deste trabalho, pretende-se estudar as características e as propriedades da toranja, assim como as interações que existem entre este fruto e os fármacos e em particular o modo como o perfil farmacocinético dos fármacos é afetado.
Drug interaction is a clinical event in which the effects of a drug are altered by the concomitant, or prior, use of another drug, food or drink. Grapefruit has been used in the fight against chronic diseases due to its anti-oxidant, antiinflammatory, anticancer, as well as anti-atherosclerotic activity. However, grapefruit is also one of the foods most studied for its potential drug interactions. Assessing the therapeutic importance of interactions between food and drugs is particularly difficult, and these interactions are mainly pharmacokinetics and very complex. Thus, food intake can influence parameters such as the absorption, distribution, metabolization and elimination of certain drugs, or, on the other hand, do not influence these parameters. Grapefruit is a known example of such interactions as it may interfere with some drugs and cause severe toxicity. Naringin, naringenin and furanocoumarins are components present in the grapefruit that are responsible for the inhibition of CYP3A4, thus leading to drug interactions. It is known that innumerable drugs interact with grapefruit juice. Many of these drugs are prescribed for the treatment of common diseases and are metabolized by cytochrome P450 3A4. P-gp and OATP are also involved in drug interactions as they undergo interactions with the polyphenolic compounds present in the grapefruit. This work intends to study the characteristics and properties of grapefruit, as well as the interactions between this fruit and drugs, and particularly to understand how the pharmacokinetic profile of the drugs is affected.
N/A
30
Paolini, Marion. "Nouvelles compositions pour l'administration d'agents thérapeutiques : Apport de la nanomédecine pour l'optimisation du ratio bénéfice-risque du traitement." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS095.
Full textAbstract:
Les différences de réponse médicamenteuse entre patients sont fréquentes, conduisant souvent à des difficultés à cibler la fenêtre thérapeutique et optimiser le traitement. Les médicaments courants sont efficaces pour seulement 25% à 60% des patients. Deux facteurs majeurs impliqués dans l’efficacité des médicaments sont leur métabolisme et clairance. Notamment, le CYP3A4 est la principale enzyme responsable du métabolisme des médicaments dans les hépatocytes ; des variations dans son activité entraînent une incertitude de dose. Pour améliorer l'efficacité du médicament, ce travail de thèse se concentre sur le développement de nano-transporteurs chargés avec des molécules naturelles inhibant le CYP3A4 et ciblant les hépatocytes, à administrer avant le médicament pour minimiser son métabolisme. Une méthodologie pour examiner les composés inhibiteurs du CYP3A4, fixer leur dose et leur temps d’administration pour une utilisation in vivo a été développée. Une première preuve de concept a été démontrée en utilisant une micelle chargée de furanocoumarine comme composé inhibiteur de CYP3A4 : des études d'efficacité antitumorale et la quantification dans la tumeur du médicament cytotoxique docetaxel, injecté après les micelles chargées de furanocoumarine, ont été engagés sur deux modèles de tumeurs xénogreffées chez la souris. Une deuxième génération de nano-transporteurs a été développée, avec des propriétés physico-chimiques optimisées pour cibler spécifiquement les hépatocytes. La démonstration de leur accumulation spécifique dans les hépatocytes et de l'amélioration supplémentaire de l’efficacité du docetaxel a été menée. Une perspective sur l'utilisation d'une telle approche pour améliorer l'efficacité des médicaments existants en oncologie est discutée, notamment pour le carcinome hépatocellulaire différenciéDifferences in drug response among patients are common, often leading to challenges in targeting the therapeutic window and optimizing the treatment. Major drugs are reported to be effective in only 25% to 60% of patients. Two important factors responsible for the effective dose of drug are drug metabolism and clearance. Notably, CYP3A4 is the main enzyme responsible for drug metabolism in hepatocytes; variations in its activity result in dose uncertainty. To improve drug’s effectiveness, this thesis work focuses on the development of nanocarriers loaded with natural CYP3A4-inhibiting molecules and targeting hepatocytes, to be administered prior to the drug to minimize its metabolism. A methodology to systematically screen CYP3A4-inhibiting compounds and set the dose and schedule for in vivo use was developed. A first proof-of-concept was demonstrated using a furanocoumarin-loaded micelle as CYP3A4-inhibiting compound: anti-tumor efficacy studies and quantification within tumor of the cytotoxic drug docetaxel, injected after furanocoumarin-loaded micelle, were engaged on two xenografted tumor models in mice. A second generation of nanocarriers was developed, with optimised physico-chemical properties to target specifically hepatocytes. The demonstration of their specific accumulation in hepatocytes and additional improvement in boosting of docetaxel was conducted. A perspective in using such an approach to enhance the effectiveness of existing drugs in oncology is discussed, notably for differentiated hepatocellular carcinoma
31
Budda, Balasubrahmanyam Mitra Ashim K. "In vitro models for simultaneous assessment of P-glycoprotein and CYP3A4 mediated drug interactions." Diss., UMK access, 2007.
Find full textAbstract:
Thesis (Ph. D.)--School of Pharmacy and Dept. of Chemistry. University of Missouri--Kansas City, 2007."A dissertation in pharmaceutical sciences and chemistry." Advisor: Ashim K. Mitra. Typescript. Vita. Description based on contents viewed July 16, 2008; title from "catalog record" of the print edition. Includes bibliographical references (leaves 154-179). Online version of the print edition.
32
Khihon, Rokhas Maria. "Development of an assay for screening drug candidates for mechanism-based inhibition of human CYP3A4." Thesis, Södertörn University College, School of Life Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-1770.
Full textAbstract:
Cytochrome P450 (CYP) constitutes a superfamily of heme- containing enzymes that catalyze the oxidative biotransformation of structurally diverse xenobiotics including pharmaceuticals and drugs. Cytochrome P450 3A4 is not only the most abundant isoform in human liver but is also responsible for metabolizing approximately 60% of therapeutic drugs. This feature makes CYP3A4 highly susceptible to both reversible and irreversible, such as mechanism-based, inhibition. Mechanism-based inhibition is characterized by being time dependent as well as NADPH and concentration dependent, when some drugs are converted by CYPs to reactive metabolites. The inactivation of CYP3A4 can be due to chemical modification of the heme, the protein, or both by covalent binding of modified heme to the protein. Compared to reversible inhibition, mechanism-based inhibition of CYP3A4 more frequently causes unfavourable drug- drug interactions (DDI), as the inactivated CYP3A4 has to be replaced by newly synthesized CYP3A4 protein. DDI can lead to higher exposure of co-administered drugs, sometimes leading to toxicity. For these reasons, drug metabolism groups within pharmaceutical companies need a well established screening assay to assess mechanism-based inactivation of major human P450 enzymes by new chemical substances that are being developed by the company. Historically, adverse drug interactions were found in clinical trials or after the drugs were commercially released. That caused pharmaceutical companies large economical losses, since a large portion of development cost was in vain.Medivir AB is a small pharmaceutical company that would like to set up a screening method to be used to test candidate drugs for CYP3A4 mechanism-based inhibition. The central aim of this master degree project was to set up a screening assay to test irreversible inhibition of CYP3A4 and validate it with known inhibitors. Using the validated assay, a number of in-house project compounds will be measured for inhibition potential and the results analyzed for structure-activity correlations. Relationships between some functional groups and mechanism-based inhibition can provide insight for improvement of drug candidates and inhibition liability. The assay was based on microsomes containing recombinant human CYP3A4 and activity measured by conversion of the substrate dibenzylfluorescein into a fluorescent product. The product was quantified by measurement of fluorescence in a 96-well plate reader. Optimization was achieved by determining the reaction linearity with time and enzyme concentration. When possible the Km for the probe substrate was also determined. The effect of different backgrounds was studied to settle on a compensation for the enzyme activity. The effect of DMSO on CYP3A4 mediated metabolism of the substrate was studied to determine the acceptable solvent concentration. The concentration responsible for 50% inhibition (IC50) was also determined for several known inhibitors and compared with literature data.
The master thesis was performed at Medivir AB, a small pharmaceutical company in Stockholm.
33
Mgwabi, Mthokozisi Muziwandile Nkosingiphile. "Genetic polymorphism in dextromethorphan metabolism by CYP2D6 and CYP3A4 enzyme isoforms / Mthokozisi Muziwandile Nkosingiphile Mgwabi." Thesis, North-West University, 2003. http://hdl.handle.net/10394/163.
Full textAbstract:
Most administered drugs are metabolised in the liver by Phase I enzymes and more
importantly by the cytochrome P450 (CYP) system. The extent of first-pass metabolism is
important in determining whether the drug will have therapeutic or adverse effects after being
administered to a patient. To date the CYP family has been shown to consist of 74 families
denoted as CYPl to CYP118, and only a few families are significantly involved in drug
metabolism. CYP3A4 is the most important isoenzyme followed by CYP2D6, CYP2C9, and
CYP2C19 with a small contribution by CYP2E1, CYP2A6, and CYPlA4. CYP2D6 and
CYP3A4 enzyme isoforms have been well established to exhibit interethnic and interindividual
variability with regard to drug metabolising capacity.
Mutation on the gene coding for a metabolising enzyme is a major cause of variation in drug
metabolism. This mutation gives rise to allelic variants producing enzymes with altered
metabolising activity. The presence of an allele with decreased metabolic activity in an
individual gives rise to the poor metabolising (PM) phenotype. When the PM phenotype
occurs at a frequency of more than 1% within a given population, then the term genetic
polymorphism applies. The aberrant metabolic capacity translates into variable drug
responses of more than 20-fold, leading to different susceptibility to sub-therapeutic effects or
adverse drug reactions. A significant number of drugs, such as the B-adrenergic blockers,
antidepressants, antipsychotic and antiarrhythmic agents, are entirely or partly metabolised by
CYP2D6 and CYP3A4. Genetic polymorphism is especially important for drugs with a narrow
therapeutic/toxicity window.
Phenotyping involves the use of a probe drug that is administered to the subject, followed by
determination of the parent drug and its metabolites in the urine. The aim of this study was to
develop and validate an HPLC method for phenotypic determination of the CYP3A4 and
CYP2D6 enzymes, followed by the application of the assay in a random heterogeneous
population of males.
Dextromethorphan (DXM) was used as an in vivo probe for simultaneous determination of the
phenotypic expression of CYP2D6 and CYP3A4. An HPLC method coupled with a
fluorescence detector was developed for the phenotypic determination of CYP2D6 and
CYP3A4 iso-enzymes as determined by the concentration of dextromethorphan/dextrophan
(DXM/DX) and dextromethorphan/3methoxy-morphinan (DXM/3MM) metabolic ratios
respectively. The compounds were separated on a phenyl column (150 x 4,6 mm, 5-um
particle size) serially connected to nitrile column (250 x 4,6 mm, 5-um particle size) using
mobile phase of 80% (1.5% glacial acetic acid and 0.1% triethyl amine in distilled water) and
20% acetonitrile. Solid phase extraction was used to extract the analytes from urine samples
using silica cartridges. The suitability of the method was demonstrated in a preliminary study
with sixteen healthy Caucasian males. After a single oral 30 mg DXM dose, the volunteers
were required to collect all urine samples voided 8 hours post oral dose. DXM/3HM and
DXM/DX metabolic ratios were determined from collected urine samples.
The method was validated for DXM and DX at a concentration range of 0.25 - 30 ug/ml, and at
0.025 - 3 ug/ml for 3MM. Calibration curves were linear with R2 values of at-least 0.999 for all
compounds of interest. Recoveries were 97%, 93%, and 65% for DX, DXM and 3MM,
respectively. The method was reproducible with intra-day precision having coefficients of
variation percentage (CV%) of less than 17% for all analytes. Inter-day precision had a CV%
of less than 14% for all analytes. The limit of detection was 30 ug/ml for all compounds. All
volunteers were classified with an extensive metaboliser (EM) phenotype. In conclusion the
method described is suitable for polymorphic determination of CYP2D6 and CYP3A4 in a
population study, and may have value in further studies planned at investigating the critical
issue of racial genetic polymorphism in ethnic groups in South Africa.Thesis (M.Sc. (Pharm.))--North-West University, Potchefstroom Campus, 2004.
34
Bakari, Sana. "Expression de 3 protéines membranaires, CYP3A4, MGST1 et P-gp, impliquées dans la détoxication cellulaire." Paris 6, 2013. http://www.theses.fr/2013PA066717.
Full textAbstract:
Les xénobiotiques présents dans l’environnement peuvent être toxiques pour les organismes, et leurs effets restent difficiles à évaluer, en particulier à cause de synergies possibles entre eux. La voie cellulaire qui aboutit à l’élimination de ces xénobiotiques est un processus de détoxication mettant en place 3 systèmes enzymatiques spécialisés et complémentaires, principalement au niveau du foie. Il s’agit des monooxygénases, principalement des cytochromes P450 (phase I), des enzymes de conjugaison, ou transférases (phase II), et des protéines d'efflux actif (phase III). Les gènes codant pour les 3 enzymes de détoxication, CYP3A4, MGST1, et P-gp, ont été exprimés dans L. Lactis selon 2 stratégies de clonage: clonage classique et clonage compatible avec Gateway. La technologie Gateway est l’un des systèmes les plus efficaces, qui a déjà permis une expression efficace de protéines membranaires de diverses origines dans L. Lactis. L’expression hétérologue de certaines protéines de notre étude (CYP3A4 et MGST1 de rat et humaine) s’est révélée efficace. En effet, avec des taux de 5% de protéines membranaires totales pour le CYP3A4, et entre 2 et 4% pour la MGST1, L. Lactis semble être un système d’expression adapté à ces 2 enzymes. Des études fonctionnelles préliminaires sur des fractions membranaires non solubilisées montrent cependant que seule la MGST1 de rat est active. La P-gp, quant à elle, n’a pas pu être exprimée dans L. Lactis pour des raisons de manque d’efficacité des méthodes de biologie moléculaire employées, dû à la grande taille de son gène. Cependant, des études enzymatiques ont été effectuées sur une P-gp exprimée dans des cellules d’insectesXenobiotics can be toxic for humans, and their biological effects remain difficult to be predicted, due to possible functional interactions between them. Cellular pathway for xenobiotic elimination consists in detoxification process including 3 enzymatic complementary systems, mainly present in liver: phase I enzymes (P450 cytochromes), phase II enzymes (transferases) and phase III active efflux transporters. CYP3A4, MGST1 and P-gp, the membrane proteins involved in this cellular detoxification and chosen in our study, were expressed in the bacterial system Lactococcus lactis using two different cloning strategies: classic and Gateway compatible cloning. It was previously showed that Gateway compatible cloning is an efficient way to produce membrane proteins in L. Lactis. Heterologous expression of CYP3A4 and rat and human MGST1was successfully established, and allowed production of 5% and 1-3% of total membrane proteins, respectively. L. Lactis seems thus to be a suitable expression system for these detoxification enzymes. Pilot functional studies, using membrane fractions showed that only rat MGST1 exhibit some enzymatic activity. Unfortunately, P-gp expression in L. Lactis could not be achieved, because of lack of efficient molecular biological tools (due to the large size of the abcb1 gene). However, enzymatic activity measurements were performed with the P-gp native form produced in transfected insect cells
35
Dapkūnas, Justas. "Citochromų P450 katalizuojamo vaistų metabolizmo kompiuterinis modeliavimas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20111003_114342-83717.
Full textAbstract:
Pagrindinis šio darbo tikslas buvo kiekybinio struktūros ir aktyvumo ryšio modelių, prognozuojančių su vaistų metabolizmu susijusias savybes, kūrimas. Modeliai, prognozuojantys CYP3A4 slopinimą ir žmogaus kepenų mikrosomų katalizuojamo metabolizmo regioselektyvumą, buvo sukurti naudojant GALAS (angl. Global, Adjusted Locally According to Similarity; Globalus, lokaliai pakoreguotas pagal panašumą) modeliavimo metodą, kuris geba įvertinti prognozės patikimumą, taip apibrėždamas modelio pritaikymo sritį. Sukurtų modelių prognozės buvo tikrinamos naudojant eksperimentinius naujų cheminių junginių duomenis. Visų globalių modelių prognozės gerėjo po korekcijų pagal panašumą, o neteisingų spėjimų skaičius buvo ženkliai mažesnis tarp aukšto patikimumo prognozių. Visgi daugiau nei pusė išorinių duomenų nepatenka į šių modelių pritaikymo sritį. GALAS modeliai gali būti gana paprastai apmokomi, pridedant naujus duomenis į lokalią modelio dalį ir apskaičiuojant reikiamą korekciją. Po tokios apmokymo procedūros CYP3A4 slopinimo modelis prisitaikė prie PubChem duomenų bazės cheminių junginių ir taip pat prie vaistų, turinčių naują cheminį karkasą. Pridėjus naujų junginių ir apmokius regioselektyvumo modelį, jis pradėjo prognozuoti naujas metabolizmo vietas. Pastarasis modelis taip pat buvo pritaikytas atskirų fermentų katalizuojamo metabolizmo prognozavimui.The main objective of this study was the development of QSAR models for drug metabolism-related properties. Novel GALAS (Global, Adjusted Locally According to Similarity) modeling method was used, which is a combination of baseline global QSAR model and local similarity based corrections. GALAS modeling method allows forecasting the reliability of prediction thus defining the model applicability domain. Models predicting CYP3A4 inhibition and regioselectivity of metabolism in human liver microsomes were developed and validated using external test sets. In all cases the baseline models already showed acceptable results, and the overall accuracy of predictions increased after the similarity based corrections. Moreover, the numbers of mispredictions reduced significantly when only results of higher reliability were taken into account. However, the original models are applicable only for less than a half of external datasets. Since the similarity correction procedure of GALAS modeling method allows simple model training, the possibility to expand the applicability domain has been tested. The CYP3A4 inhibition model was successfully adapted to PubChem data and compounds with a novel chemical scaffold. After training the regioselectivity model new metabolism sites could be identified in compounds of new chemical class. Moreover, this model was adapted for human cytochrome P450 isoform profiling.
36
Dapkūnas, Justas. "Computational modeling of cytochrome P450-mediated drug metabolism." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20111003_114651-54627.
Full textAbstract:
The main objective of this study was the development of QSAR models for drug metabolism-related properties. Novel GALAS (Global, Adjusted Locally According to Similarity) modeling method was used, which is a combination of baseline global QSAR model and local similarity based corrections. GALAS modeling method allows forecasting the reliability of prediction thus defining the model applicability domain. Models predicting CYP3A4 inhibition and regioselectivity of metabolism in human liver microsomes were developed and validated using external test sets. In all cases the baseline models already showed acceptable results, and the overall accuracy of predictions increased after the similarity based corrections. Moreover, the numbers of mispredictions reduced significantly when only results of higher reliability were taken into account. However, the original models are applicable only for less than a half of external datasets. Since the similarity correction procedure of GALAS modeling method allows simple model training, the possibility to expand the applicability domain has been tested. The CYP3A4 inhibition model was successfully adapted to PubChem data and compounds with a novel chemical scaffold. After training the regioselectivity model new metabolism sites could be identified in compounds of new chemical class. Moreover, this model was adapted for human cytochrome P450 isoform profiling.Pagrindinis šio darbo tikslas buvo kiekybinio struktūros ir aktyvumo ryšio modelių, prognozuojančių su vaistų metabolizmu susijusias savybes, kūrimas. Modeliai, prognozuojantys CYP3A4 slopinimą ir žmogaus kepenų mikrosomų katalizuojamo metabolizmo regioselektyvumą, buvo sukurti naudojant GALAS (angl. Global, Adjusted Locally According to Similarity; Globalus, lokaliai pakoreguotas pagal panašumą) modeliavimo metodą, kuris geba įvertinti prognozės patikimumą, taip apibrėždamas modelio pritaikymo sritį. Sukurtų modelių prognozės buvo tikrinamos naudojant eksperimentinius naujų cheminių junginių duomenis. Visų globalių modelių prognozės gerėjo po korekcijų pagal panašumą, o neteisingų spėjimų skaičius buvo ženkliai mažesnis tarp aukšto patikimumo prognozių. Visgi daugiau nei pusė išorinių duomenų nepatenka į šių modelių pritaikymo sritį. GALAS modeliai gali būti gana paprastai apmokomi, pridedant naujus duomenis į lokalią modelio dalį ir apskaičiuojant reikiamą korekciją. Po tokios apmokymo procedūros CYP3A4 slopinimo modelis prisitaikė prie PubChem duomenų bazės cheminių junginių ir taip pat prie vaistų, turinčių naują cheminį karkasą. Pridėjus naujų junginių ir apmokius regioselektyvumo modelį, jis pradėjo prognozuoti naujas metabolizmo vietas. Pastarasis modelis taip pat buvo pritaikytas atskirų fermentų katalizuojamo metabolizmo prognozavimui.
37
Neri, Numa Iramaia Angelica 1978. "Polimorfismo CYP3A4-290A>G relacionado ao metabolismo do mesilato de imatinibe, no prognóstico de pacientes com leucemia mielóide crônica." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/308611.
Full textAbstract:
Orientador: Carmen Silvia Passos LimaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-21T21:59:05Z (GMT). No. of bitstreams: 1 Numa_IramaiaAngelicaNeri_M.pdf: 4547636 bytes, checksum: 22548046dff40a3bb4e586230e3f13b7 (MD5) Previous issue date: 2012
Resumo: O mesilato de imatinibe (MI) é o tratamento de escolha para pacientes com leucemia mielóide crônica (LMC) em fase crônica, mas a resposta ao medicamento é variável em indivíduos distintos. A CYP3A4 é a principal enzima responsável pelo metabolismo hepático do MI. O alelo variante G do polimorfismo CYP3A4 A-290G codifica menor quantidade de enzima do que o alelo selvagem A, mas o papel do referido polimorfismo em pacientes com LMC tratados com MI é desconhecido. Os objetivos deste trabalho foram os de avaliar a eficácia, a toxicidade a sobrevida livre de progressão (SLP) e global (SG) de pacientes com LMC durante a administração de MI e verificar se estes parâmetros são alterados pela variabilidade interindividual no metabolismo do fármaco, relacionada ao polimorfismo CYP3A4 A-290G. Foram avaliados 100 pacientes com LMC em FC precoce atendidos no Centro de Hematologia e Hemoterapia da UNICAMP. O diagnóstico da LMC, o exame hematológico, o cariótipo, a pesquisa do gene BCR-ABL e os genótipos do polimorfismo CYP3A4 A-290G foram realizados por métodos convencionais. Os pacientes receberam o MI na dose de 400mg e a resposta ao tratamento foi avaliada segundo os critérios do European Leukemia Net. Identificamos respostas hematológicas, citogenética e molecular similares às previamente descritas. A taxa de resposta hematológica foi de 95% ao longo do estudo. Aos doze meses, as respostas citogenética completa ou parcial foram de 72% e 11% respectivamente. Já as taxas de respostas moleculares completas e maiores aos 22 meses foram de 28% e 26%, respectivamente. A sobrevida global foi de 94% aos 92 meses bem como a sobrevida livre de progressão para as fases avançadas da doença. Observamos que pacientes com resposta citogenética completa ou parcial e molecular xiv completa ou maior apresentaram maior SLP e SG do que os demais. Cerca de 13% dos pacientes era portadores do genótipo AG do polimorfismo CYP3A4 A-290G, o qual esteve associado à obtenção de resposta molecular completa tardia e tendência à menor SLP e SG. Apesar da hipótese do alelo variante (G) exibir um fenótipo metabolizador lento associado a uma menor taxa de biotransformação do MI e portando maior risco de reações tóxicas, não observamos diferenças entre as toxicidades hematológicas e não hematológica (P= 0,28). Assim, concluímos que nossos pacientes respondem de forma similar ao MI do que os demais e que o polimorfismo CYP3A4 A-290G pode vir a funcionar como biomarcador de resposta ao fármaco
Abstract: Imatinib (IM) is widely recognized as the standard of care in the first-line treatment of CML but the response to the drug is variable in different subjects. CYP3A4 is the main enzyme responsible for the hepatic metabolism of Imatinib. The G variant allele of the polymorphism A-290G encoding least amount of enzyme than the wild-type allele, but the role of this polymorphism in CML patients treated with Imatinib is unknown. The aims of this study were to assess the efficacy, toxicity, progression-free survival (PFS) and overall survival (OS) of patients with CML during the administration of Imatinib and check if these parameters are affected y interindividual variability in drug metabolism, the polymorphism related to CYP3A4 A-290G. We evaluated 100 patients with CML newly diagnosed at Center of Hematology and Hemoterapy of UNICAMP. The diagnosis of CML, hematology, karyotyping, research the BCR-ABL gene polymorphism and CYP3A4 genotypes A-290G were performed by conventional methods. Patients received a dose of 400mg IM and treatment response was assessed according to the criteria of the European Leukemia Net responses identified hematologic, cytogenetic and molecular similar to those previously described. The hematologic response rate was 95% throughout the study. At 22 months the complete or partial cytogenetic responses were 72% and 11% respectively. The complete molecular response rates at 22 months were 28% and 26%, respectively. Overall survival (OS) was 94% at 92 months and the progression-free survival (PFS) for advanced stages of the disease. We observed that patients with partial or complete cytogenetic response and major molecular and complete PFS and OS showed higher than other. We observed that patients with partial or complete cytogenetic response and major molecular xvi and complete PFS and OS showed higher than others. About 13% of patients were of AG genotype polymorphism of the CYP3A4 -290A>G, which was associated with achieving complete molecular response and late tendency to lower PFS and OS. Despite the possibility of variant allele (G) display a slow metabolizer phenotype associated with a lower rate of biotransformation of IM and carrying greater risk of toxic reactions, no significant differences between hematological and non hematological toxicities (P= 0,28). Thus, we conclude that our patients respond similary to IM than others and that the polymorphism CYP3A4 -290A>G might function as a biomarker of response to the drug
Mestrado
Ciencias Basicas
Mestra em Clínica Médica
38
Schrøder-Aasen, Torstein. "Effects of Purple Coneflower (Echinacea purpurea) on CYP3A4 Metabolism and P-glycoprotein Mediated Transport in Vitro." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kreftforskning og molekylær medisin, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19766.
Full textAbstract:
Solhatt har blitt et av de vanligste urtepreparatene på verdensmarkedet, og markedsføres for sin effekt mot luftveisinfeksjoner og forkjølelse. Sambruk av naturpreparater og legemidler forekommer ofte, og det er kjent at urtepreparater kan påvirke kroppens omsetning av legemidler. I verste fall kan konsekvensene være dødelige. Derfor er kunnskap rundt slike interaksjoner mellom urter og legemidler en viktig del av pasientsikkerheten. Cytokrom P-450 3A4 (CYP3A4) er et spesifikt protein (enzym) som bidrar i omdanningen og nedbrytingen av ca 50% av alle markedsførte legemidler. P-glykoprotein er et transportprotein som bidrar til å transportere legemidler ut av kroppen eller redusere opptaket fra tarm. Begge disse proteinene kan påvirkes av urter slik at legemiddel-omsetningen og den kliniske effekten av legemidler kan endres (interaksjoner). Hovedmålet med denne avhandlingen var å vurdere, gjennom ulike laboratorieteknikker, effekten av rød solhatt på CYP3A4 og P-glykoprotein, og å kartlegge eventuelle mekanismer til grunn for påvirkningen. Solhatt viste i hovedsak en svak hemming av aktiviteten til P-glykoprotein. Samtidig fant vi at solhatt i noe større grad reduserte legemiddelnedbrytingen til CYP3A4. Effekten på CYP3A4 var forskjellig for ulike solhatt-produkter, men hovedtendensen var en svak hemming. Det er generelt vanskelig å anslå den kliniske betydningen av laboratoriefunn alene. For hvert av de undersøkte proteinene er den hemmende effekten fra solhatt trolig liten, men vi vet at disse to proteinene virker samtidig, og en forsterket effekt i kroppen kan ikke utelukkes. Mekanismene til grunn for hemmingen ble også studert. Studiene viste at solhatt har minst to ulike mekanismer for hemming av CYP3A4. Mekanismene var annerledes når solhatt var en del av et multi-preparat med andre urter som for eksempel svarthyll. Både for CYP3A4 og P-glykoprotein tyder de kompliserte hemmingsmekanismene på at to eller flere ulike substanser i solhatt-preparatet påvirker proteinet samtidig. Det er verdt å merke seg at solhatt trolig er en ikke-reversibel hemmer av CYP3A4, som vil kunne gi en langvarig reduksjon i kroppens evne til å omsette legemidler, og dermed øke sjansen vesentlig for kliniske interaksjonseffekter med legemidler. Samlet har vi vist at solhatt i beskjeden grad påvirker CYP3A4 og P-glykoprotein i laboratorieforsøk. Vi har ikke grunn til å tro at den kliniske effekten er av vesentlig betydning. På bakgrunn av en ikke-reversibel hemming av CYP3A4 kan vi likevel ikke bedømme solhatt som ufarlig med tanke på klinisk interaksjonsrisiko. Selv om vi ikke kan gi klinisk konklusive svar, har studiene brakt frem mer kunnskap omkring solhatts påvirkning på legemiddelomsetningen og om legemiddel-urt-interaksjoner generelt.
39
Lieker, Ina [Verfasser]. "Induktion der CYP3A4-mRNA-Bildung in den Zelllinien HepG2 und Colo320 durch antiretrovirale Medikamente / Ina Lieker." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2014. http://d-nb.info/1058105000/34.
Full text
40
Row, Eleanor Catherine. "Design, synthesis and evaluation of coumarin and furanocoumarin compounds as inhibitors of CYP3A4 and P-glycoprotein." Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401162.
Full text
41
Assis, Joana Isabel Gomes. "" Cancro do Óvario: Influência de Polimorfismos nos Genes CYP3A4 e LIG4 na Susceptibilidade e Resposta Farmacogenómica "." Dissertação, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/57187.
Full text
42
Assis, Joana Isabel Gomes. "" Cancro do Óvario: Influência de Polimorfismos nos Genes CYP3A4 e LIG4 na Susceptibilidade e Resposta Farmacogenómica "." Master's thesis, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/57187.
Full text
43
Michaut, Anaïs. "Mise au point d'un modèle de stéatose hépatique liée à l'obésité : application à l'étude de la toxicité du paracétamol." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1B015/document.
Full textAbstract:
L'obésité et les maladies du foie associées (NAFLD) augmentent le risque et la sévérité de l’hépatotoxicité induite par certains xénobiotiques, mais les mécanismes impliqués sont encore mal compris. Pour l'éthanol et le paracétamol (APAP), le rôle du cytochrome P450 2E1 (CYP2E1) hépatique est suspecté car l'activité de cette enzyme est augmentée au cours de ces pathologies dysmétaboliques. Le 1er objectif de notre travail expérimental a été de mettre au point un modèle cellulaire de NAFLD caractérisé non seulement par l'accumulation de triglycérides mais aussi par l’augmentation de l'activité du CYP2E1. Pour cela, des cellules humaines HepaRG différenciées ont été incubées pendant une semaine avec de l'acide stéarique ou de l'acide oléique, en présence de 3 concentrations différentes d'insuline. Les triglycérides cellulaires et l'expression de gènes induits au cours de la stéatose étaient similaires avec les deux acides gras. Cependant, l'activité du CYP2E1 était significativement augmentée uniquement par le stéarate et ceci était associé à une diminution de l'activité du CYP3A4, une autre caractéristique des NAFLD. L’activité du CYP2E1 dans les cellules HepaRG était réduite par l'insuline d'une manière concentration-dépendante et cet effet était reproduit sur des hépatocytes humains en culture primaire. Ainsi, l'activité du CYP2E1 était la plus élevée dans les cellules HepaRG cultivées avec du stéarate et sans insuline. Le 2ème but de notre étude était ensuite d'évaluer la cytotoxicité de l’APAP sur des cellules HepaRG présentant ou non une stéatose et une induction du CYP2E1. Des expériences avec une large gamme de concentrations d’APAP (de 1 à 20 mM) indiquaient que la perte cellulaire d'ATP et du glutathion (GSH) était presque toujours plus forte en présence de stéarate. Dans les cellules prétraitées avec le chlorméthiazole (CMZ, un inhibiteur du CYP2E1), la moindre diminution d’ATP était plus importante en présence de stéarate, avec de faibles (2,5 mM) ou de fortes (20 mM) concentrations d’APAP. Cependant, en l'absence d'insuline, la moindre chute d’ATP induite par le CMZ était significativement plus forte uniquement pour 20 mM d’APAP. Étonnamment, suite au prétraitement par le CMZ, il n'y avait pas de protection vis-à-vis de la diminution du GSH et de la formation des adduits APAP-protéines. Enfin, les concentrations du métabolite APAP-glucuronide étaient significativement augmentées en présence d'insuline. Ainsi, lorsqu’elle est étudiée dans des conditions spécifiques de culture, la lignée cellulaire HepaRG semble être un modèle intéressant de NAFLD, notamment en ce qui concerne les activités du CYP2E1 et du CYP3A4. Nos données suggèrent aussi que l’induction du CYP2E1 observée au cours des NAFLD pourrait être secondaire à l'accumulation de certains acides gras et à la présence d’une faible signalisation insulinique dans le foie. Ainsi, ce modèle cellulaire peut être utilisé pour mettre en évidence les principaux facteurs métaboliques et hormonaux favorisant hépatotoxicité de l’APAP chez les personnes obèses. Cette thèse inclut également une revue de la littérature sur l’hépatotoxicité de l’APAP dans le contexte de l’obésité et des NAFLD (Michaut et al., Liver Int 2014)Obesity and nonalcoholic fatty liver disease (NAFLD) are able to increase the risk and the severity of hepatotoxicity induced by some xenobiotics including drugs, but the involved mechanisms are still poorly understood. For toxic compounds such as ethanol and acetaminophen (APAP), a role of hepatic cytochrome P450 2E1 (CYP2E1) is suspected since the activity of this enzyme is consistently enhanced during obesity and NAFLD. The first aim of our experimental study was to set up a cellular model of NAFLD characterized not only by triglyceride accumulation but also by higher CYP2E1 activity. To this end, differentiated human HepaRG cells were incubated during one week with stearic acid, or oleic acid, in the presence of 3 different concentrations of insulin. Cellular triglycerides and the expression of lipid-responsive genes were similar with both fatty acids. However, CYP2E1 activity was significantly increased only by stearate and this was associated with lower CYP3A4 activity, another metabolic feature reported in NAFLD. CYP2E1 activity in HepaRG cells was reduced by insulin in a concentration-dependent manner and this effect was reproduced in cultured primary human hepatocytes. Hence, the highest CYP2E1 activity was observed in HepaRG cells with stearate and without insulin. Next, the second aim of our study was to assess APAP cytotoxicity in HepaRG cells presenting or not lipid accretion and CYP2E1 induction. Experiments with a large range of APAP concentrations (1 to 20 mM) showed that the cellular loss of ATP and glutathione (GSH) was almost always stronger in the presence of stearic acid. In cells pretreated with the CYP2E1 inhibitor chlormethiazole (CMZ), recovery of cellular ATP was significantly higher in the presence of stearic acid with both low (2.5 mM) and high (20 mM) concentrations of APAP. However, in the absence of insulin, CMZ-induced ATP recovery was significantly greater only for 20 mM of APAP. Surprisingly, there was no recovery of cellular GSH and no reduction of APAP-protein adducts following CMZ pretreatment. Finally, levels of APAP-glucuronide were significantly enhanced in the presence of insulin. Hence, when studied in specific conditions of culture, the HepaRG cell line can be a valuable model of human NAFLD, especially regarding CYP2E1 and CYP3A4 activity. Our data also suggest that higher CYP2E1 activity in NAFLD could be secondary to the hepatic accumulation of some fatty acids and to the presence of low insulin signaling. This cellular model can be thus used to unveil the main metabolic and hormonal factors favoring APAP hepatotoxicity in obese individuals. This thesis also includes a review on APAP hepatotoxicity in the context of obesity and NAFLD (Michaut et al., Liver Int 2014)
44
Chefson, Amandine. "Towards the use of P450 enzymes in synthesis : cofactor replacement and activity of CYP3A4 in non-aqueous media." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100784.
Full textAbstract:
Enantioselective synthesis is one of the most important challenges of today's synthetic chemists. In particular, the hydroxylation of non-activated C-H bonds remains a significant challenge that few chemical catalysts have succeeded to overcome. The P450 enzymes, a family of heme-containing monooxygenases including more than 5000 known isoforms, are gaining considerable attention due to their ability to catalyze the very difficult regio- and stereo-selective oxidation of inactivated C-H bonds. The use of such enzyme is however limited by their functional complexity, low activity, need for cofactors, and poor stability. In this thesis, we elected to study the human P450 CYP3A4, because of its high substrate promiscuity. The first part of the project involved the replacement of the required cofactors (NADPH and cytochrome P450 reductase) by some cheap hydrogen peroxide donors or organic peroxides. Several surrogates, such as sodium percarbonate and cumene hydroperoxide, were found to be efficient at replacing the natural cofactor, without a significant loss of stability and activity. The second part of this thesis deals with optimization of the lyophilization conditions. Among the numerous additives tested, some sugars led to significant lyoprotection during the freeze-drying process. Finally, in the third part, the effect of the presence of organic solvents and ionic liquids on CYP3A4 activity was evaluated.
45
Mirghani, Rajaa A. "Quinine metabolism in man : emphasis on the 3-hydroxylation as a biomarker reaction for the activity of CYP3A4 /." Stockholm : [Karolinska institutets bibl.], 2002. http://diss.kib.ki.se/2002/91-7349-174-8.
Full text
46
Heyckendorf, Jan Sebastian [Verfasser]. "Bedeutung der Kandidatengene P2RY12 und Cyp3A4 für die Clopidogrel-Resistenz am phänotypischen Beispiel von Stentthrombosen / Jan Sebastian Heyckendorf." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2011. http://d-nb.info/1017493243/34.
Full text
47
Patel, Jignesh Mitra Ashim K. "P-glycoprotein mediated efflux and CYP3A4 mediated metabolism of HIV-protease inhibitor, ritonavir, and its interaction with pure herbal constituents." Diss., UMK access, 2004.
Find full textAbstract:
Thesis (Ph. D.)--School of Pharmacy and Dept. of Chemistry. University of Missouri--Kansas City, 2004."A dissertation in pharmaceutical science and chemistry." Advisor: Ashim K. Mitra. Typescript. Vita. Description based on contents viewed Feb. 27, 2006; title from "catalog record" of the print edition. Includes bibliographical references (leaves 175-199). Online version of the print edition.
48
FREITAS, Lênis Medeiros de. "Avaliação do perfil metabólico da estavudina através do emprego da bioconversão e da modelagem molecular do citocromo P-450 CYP3A4." Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/2132.
Full textAbstract:
Made available in DSpace on 2014-07-29T16:11:53Z (GMT). No. of bitstreams: 1
dissertacao lenis farmacia.pdf: 979538 bytes, checksum: 87e0e8efbc86129446e270aa9e9aa8b5 (MD5)
Previous issue date: 2009-06-26Before the approval of an active compound, metabolism studies are necessary to ensure its safety, once active metabolites could be synthesized during human biotransformation. The use of eukaryotic microorganisms for the study of drug metabolism has been widely explored, due to its capability of producing metabolites similar to the mammalians, and in silico studies consist in a fast strategy when compared with traditional metabolism studies. In this context, molecular modeling, using docking of molecules of interest in the active site of enzymes involved in drug metabolism, is a useful tool to evaluate the interactions between drug and receptor, because it could predict favorable orientations that could be biotransformated. In this work, sixteen filamentous fungi strains, obtained from collections and isolated from soil in the central Brazil, were evaluated for their capability of the antiretroviral stavudine biotransformation, also complemented by animal metabolism studies and molecular modeling of the most relevant cytochrome P450 isoform of human metabolism: CYP3A4. From the bioconversion experiments, the fungus Cunninghamella elegans ATCC 26169 was capable of metabolize stavudine, forming mammalian metabolites, producing the thymine derivative. Dynamic molecular studies demonstrated that the most probable reactions for stavudine, catalyzed by CYP3A4, involves hydroxylation of methyl group (position C-7) and the double bond epoxidation of the furanic ring, showing the importance of some residues of the active site in this process, like Arg212
Antes da aprovação de uma substância ativa, estudos do metabolismo são necessários para garantir sua segurança, uma vez que metabólitos ativos podem ser produzidos durante a biotransformação no organismo humano. O uso de microrganismos eucarióticos para estudos do metabolismo de fármacos tem sido bastante explorado, devido à sua capacidade de produzir metabólitos semelhantes aos de mamíferos, e os estudos in silico consistem em uma estratégia rápida quando comparada com os estudos tradicionais. Dentro deste contexto, a modelagem molecular, utilizando docking de moléculas de interesse no sítio ativo de enzimas envolvidas no metabolismo, é empregada para a avaliação das interações entre o fármaco e a proteína, podendo prever as orientações favoráveis à biotransformação. Neste trabalho, dezesseis cepas de fungos filamentosos, obtidas de coleções e isoladas do Cerrado, foram utilizadas para o estudo do metabolismo do anti-retroviral estavudina, e complementadas pelo estudo do metabolismo animal e pelo emprego da modelagem molecular da isoforma humana de citocromo P-450 mais importante para o metabolismo: CYP3A4. A partir dos experimentos de bioconversão, a cepa Cunninghamella elegans ATCC 26169 foi capaz de biotransformar a estavudina de forma semelhante aos mamíferos, produzindo o derivado timina. Os estudos de dinâmica molecular, por sua vez, demonstraram que as reações mais prováveis para a estavudina, catalisadas pelo CYP3A4, envolvem a hidroxilação da metila (posição C-7) e a epoxidação da dupla ligação pertencente ao anel furânico, evidenciando, ainda, a importância de determinados resíduos do sítio ativo neste processo, como a arginina 212
49
Rossato, Juliana Pereira Maura. "Avaliação da permeabilidade intestinal da furosemida e da furosemida complexada com hidroxipropil-β-ciclodextrina por meio do modelo de perfusão in situ de passagem tripla em ratos." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-30032016-145037/.
Full textAbstract:
A furosemida é um fármaco de ação diurética e amplamente utilizado em tratamentos de doenças renais, cardíacas e pulmonares. Sua absorção é problemática e de alta variabilidade inter e intraindividual. Este fármaco tem sido classificado como pertencente às classes II (baixa solubilidade e alta permeabilidade) ou IV (baixa permeabilidade e baixa solubilidade) do Sistema de Classificação de Biofarmacêutica (SCB). Em estudos anteriores da equipe de pesquisa, SPRICIGO e colaboradores (2008) e SILVA (2014) desenvolveram complexos de furosemida com hidroxipropil-β-ciclodextrina que permitiram a otimização da solubilidade deste fármaco. Entretanto, dados sobre a sua permeabilidade intestinal, quando complexado, não foram determinados. Somando-se a isto, a literatura apresenta informações distintas em relação a este parâmetro, o que corrobora a importância de se avaliar a permeabilidade deste fármaco. Diversas técnicas têm sido empregadas para a avaliação da permeabilidade intestinal dos fármacos. No presente trabalho empregou-se o modelo de perfusão in situ de passagem tripla, cuja técnica possibilita avaliar a permeabilidade em três segmentos diferentes em um mesmo animal e ainda, apresenta características interessantes, pois trata-se de um método que proporciona, durante todo o experimento, condições mais próximas daquelas encontradas durante o processo in vivo de absorção de fármacos no intestino tais como: suprimento sanguíneo, inervação intacta, preservação das proteínas transportadoras de membranas e presença da camada de muco. O presente trabalho foi dividido nas seguintes etapas: (i) obtenção da furosemida complexada com hidroxipropil-β-ciclodextrina, (ii) caracterização dos fármacos utilizando técnicas de análises térmicas, (iii) estudo de perfusão in situ de passagem tripla nos três segmentos intestinais (duodeno, jejuno e íleo) de ratos machos Wistar na ausência e na presença de inibidores da glicoproteína P e de enzimas metabolizadoras CYP3A4 com posterior análise estatística do impacto da ciclodextrina e inibidores na permeabilidade da furosemida e; (iv) análise histológica das microvilosidades intestinais após o ensaio de perfusão in situ nos três segmentos intestinais. Os valores encontrados em cada segmento para furosemida complexada foram: 8,58 ± 0,002 x 10-5 cm.s-1; 9,15 ± 0,003 x10-5 cm.s-1 e; 8,06 ± 0,002 x 10-5 cm.s-1, respectivamente para duodeno, jejuno e íleo enquanto que para furosemida pura encontraram-se os seguintes: 3,42 ± 0,08 x 10-5 cm.s-1 para duodeno; 3,87 ± 0,11 x 10-5 cm.s-1 para jejuno e 3,08 ± 0,001 x 10-5 cm.s-1 para íleo. Assim sendo, os valores obtidos para a permeabilidade da furosemida complexada foram significativamente superiores (p < 0,05) aos da furosemida pura, sugerindo que, a ciclodextrina pode ter influência no mecanismo de transporte da furosemida, que é via passiva paracelular. Quanto aos mecanismos envolvidos na permeabilidade da furosemida através dos enterócitos, pode-se sugerir que observou-se pouca influência dos inibidores da glicoproteína P (P-gp) e da enzima CYP3A4, sugerindo que não há uma participação importante destes mecanismos em sua absorção intestinal.Furosemide, which is a diuretic drug, is widely used in heart, kidney and pulmonary disease treatments. The absorption is problematic with high variability inter and intra individuals. This drug has been classified as belonging to class II (low solubility and high permeability) or IV (low permeability and low solubility) of the Biopharmaceutical Classification System (BCS). In previous studies of the research team, Spricigo and colleagues (2008) and Silva (2014) developed complex of furosemide with hydroxypropyl-β-cyclodextrin which allowed the optimization of the solubility of this drug. However, datas concerning it\'s intestinal permeability, when complexed, have not been determined. Addicted to this, the literature shows many information regarding to this parameter, which confirms the importance of the evaluation of the permeability of this drug. Some techniques have been employed in order to evaluate the intestinal permeability of drugs. In the present work, a triple single-pass intestinal perfusion technique was used for three different segments. This technique enables the evaluation of the permeability of different segments in the same animal and also has interesting features such as: it provides during all the experiment conditions closer to those found in in vivo process of a drug absorption in the gut; blood supply; intact innervations; preservation of membrane transporter proteins and presence of mucus layer. This study was divided into the following steps: (i) obtaining furosemide complexed with hydroxypropyl-β-cyclodextrin, (ii) characterization of drugs using techniques of thermal analysis, (iii) perfusion study in situ triple passage in three segments (duodenum, jejunum and ileum) from male Wistar rats in the absence and presence of inhibitors of P-glycoprotein and metabolizing enzymes CYP3A4 and subsequential statistical analysis of the impact of the cyclodextrin and the inhibitors in the permeability of furosemide and (iv) histological analysis of intestinal microvilli after in situ perfusion assay in three segments. The values found in each segment for complexed furosemide were: 8,58 ± 0,002 x 10-5 cm.s-1; 9,15 ± 0,003 x 10-5 cm.s-1; 8,06 ± 0,002 x 10-5 cm.s-1, respectively for duodenum, jejunum and ileum while for pure furosemide, the values were: 3,42 ± 0,08 x 10-5 cm.s-1 to duodenum; 3,87 ± 0,11 x 10-5 cm.s-1 to jejunum and 3,08 ± 0,001 x 10-5 cm.s-1 to ileum. Thus, the values obtained for the permeability of the complexed furosemide were significantly higher (p < 0,05) than those found for pure furosemide, suggesting that the cyclodextrin might have an influence on the transport mechanism of furosemide, which is passive paracellular route. About the mechanisms involved in the permeability of furosemide through the enterocytes, it can be suggested that there was little effect of P-glycoprotein (P-gp) inhibitors and CYP3A4 enzyme, suggesting that there is an important role of these mechanisms in the furosemide intestinal absorption.
50
TOSCANO, Paulo Martins. "Perfil molecular em genes cyp3a4 e cyp2j2: um caminho para a farmacogenética do Rivaroxaban em uma população do Norte do Brasil." Universidade Federal do Pará, 2014. http://repositorio.ufpa.br/jspui/handle/2011/8911.
Full textAbstract:
Submitted by Hellen Luz (hellencrisluz@gmail.com) on 2017-07-24T16:22:21Z
No. of bitstreams: 2
license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Dissertacao_PerfilMolecularGenes.pdf: 1048037 bytes, checksum: d0479df3122ed434a7a26c2cbc4534bf (MD5)Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-07-25T13:09:26Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PerfilMolecularGenes.pdf: 1048037 bytes, checksum: d0479df3122ed434a7a26c2cbc4534bf (MD5)
Made available in DSpace on 2017-07-25T13:09:26Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_PerfilMolecularGenes.pdf: 1048037 bytes, checksum: d0479df3122ed434a7a26c2cbc4534bf (MD5) Previous issue date: 2014-01-23
Nos últimos anos, novos anticoagulantes têm sido desenvolvidos com o objetivo de minimizar as dificuldades encontradas no manejo clínico das drogas convencionais, porém não existem dados publicados sobre a sua farmacogenética. Diante da hipótese de que os polimorfismos relacionados à sua metabolização possam ser fonte de variabilidade genética, o presente estudo objetiva realizar inferências de epidemiologia molecular dos polimorfismos nos genes CyP3a4 (rs2246709) e CyP2j2 (rs890293), relacionados ao metabolismo do Rivaroxaban, um novo inibidor direto do fator Xa. São analisadas 136 amostras de indivíduos saudáveis de uma população do Norte do Brasil que apresenta um elevado grau de mistura interétnica. Para alcançar o objetivo farmacogenético foi realizada, em paralelo, análise de ancestralidade genômica nos indivíduos investigados. Os resultados demonstraram diferenças significativas entre os genótipos do CyP3a4 observados no estudo, quando comparados a todas as populações ancestrais para o polimorfismo 99365719 a>G (P<0,05). a população miscigenada do Norte do Brasil, portanto, apresentou diferença na distribuição das frequências genotípicas em relação aos grupos ancestrais, formadores de nossa população. O mesmo achado não é observado para polimorfismo do gene do CyP2j2. Destaca-se que o polimorfismo no gene do CyP3a4, na amostra investigada, sofre influência da contribuição étnica européia individual. Considerando, a elevada miscigenação que caracteriza a população local e o avanço da Farmacogenômica na medicina atual, os dados podem contribuir para a melhor compreensão da farmacogenética do novo anticoagulante.
In recent years, new anticoagulants have been developed with the purpose of minimizing the difficulties encountered in the clinical management of conventional dru- gs, but there are no published data on its pharmacogenetics. Considering the hypothe- sis that polymorphisms related to its metabolism may be the source of genetic variability, this study aims to make inferences on molecular epidemiology of polymorphisms in CyP3a4 (rs2246709) and CyP2j2 (rs890293) genes related to the metabolism of Rivaroxaban, a new direct factor Xa inhibitor. 136 samples from healthy individuals in a population of northern Brazil with a high degree of inter-ethnic mix, so as to guarantee that the pharmacogenetic goal was achieved, have been subjected to a parallel analysis of genomic ancestry for the individuals investigated. The results sho- wed significant differences among genotypes for CyP3a4 observed in the study com- pared to all ancestral populations for a polymorphism 99,365,719 a> G ( P < 0.05). The mixed population of northern Brazil, therefore, showed differences in the distribution of genotype frequencies in relation to ancestral groups, forming our population. The same finding was not observed for the CyP2j2 gene polymorphism. It is noteworthy that the polymorphism in the CyP3a4 gene in the investigated sample is influenced by indivi- dual ethnic European contribution. Considering the high miscegenation featuring local people, and the advancement of Pharmacogenomics in current medicine, such data can contribute to a better understanding of the pharmacogenetics of that new anticoagulant.