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Tissue slices can be made from organs, such as liver, kidney, brain, and heart, and from various species including humans, dogs, non-human primates, rats and mice. It has been demonstrated that human and rat liver slices are viable for up to 2 days, and liver slices have been extensively used as an in vitro method to study hepatic drug metabolism and toxicity in humans. The objective of this study was to determine the utility of canine hepatic slices as an in vitro model for studying drug metabolism and hepatotoxicity in dogs. Canine hepatic slices were incubated in media containing various drugs to determine the hepatotoxicity of the agents and the ability of the slices to metabolize the drugs. The toxicity of phenobarbital, primidone, lidocaine and carprofen to canine hepatic slices was assessed by determining changes in supernatant concentrations of potassium ions and adenosine triphosphate (ATP); histologic lesions were determined as necrosis, extent of vacuolation and severity of vacuolation. Xenobiotic drug metabolizing enzymatic activity was investigated by determining the metabolism of lidocaine to monoethylglycinexylidide (MEGX), and administration of phenobarbital plus primidone was used as a positive control for hepatotoxicity in dogs. The function of drug-metabolizing enzymes was demonstrated by the successful metabolism of lidocaine to MEGX. Carprofen, a drug which causes idiosyncratic hepatic disease in dogs, did not show any hepatotoxicity at concentrations of 10, 50 and 100 µg/ml using potassium ion levels, ATP concentrations and histology as indicators of hepatotoxicity. Slices incubated in media without drug showed no toxicity over 24 hours based on potassium ion and ATP supernatant concentrations while significant increases in histologic lesions were noted at 8, 12 and 24 hours. Canine hepatic slices were a useful model for examining drug metabolism and toxicity for up to 24 hours.

Tissue slices can be made from organs, such as liver, kidney, brain, and heart, and from various species including humans, dogs, non-human primates, rats and mice. It has been demonstrated that human and rat liver slices are viable for up to 2 days, and liver slices have been extensively used as an in vitro method to study hepatic drug metabolism and toxicity in humans. The objective of this study was to determine the utility of canine hepatic slices as an in vitro model for studying drug metabolism and hepatotoxicity in dogs. Canine hepatic slices were incubated in media containing various drugs to determine the hepatotoxicity of the agents and the ability of the slices to metabolize the drugs. The toxicity of phenobarbital, primidone, lidocaine and carprofen to canine hepatic slices was assessed by determining changes in supernatant concentrations of potassium ions and adenosine triphosphate (ATP); histologic lesions were determined as necrosis, extent of vacuolation and severity of vacuolation. Xenobiotic drug metabolizing enzymatic activity was investigated by determining the metabolism of lidocaine to monoethylglycinexylidide (MEGX), and administration of phenobarbital plus primidone was used as a positive control for hepatotoxicity in dogs. The function of drug-metabolizing enzymes was demonstrated by the successful metabolism of lidocaine to MEGX. Carprofen, a drug which causes idiosyncratic hepatic disease in dogs, did not show any hepatotoxicity at concentrations of 10, 50 and 100 µg/ml using potassium ion levels, ATP concentrations and histology as indicators of hepatotoxicity. Slices incubated in media without drug showed no toxicity over 24 hours based on potassium ion and ATP supernatant concentrations while significant increases in histologic lesions were noted at 8, 12 and 24 hours. Canine hepatic slices were a useful model for examining drug metabolism and toxicity for up to 24 hours.

Orientador: Fernando Ferreira Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T08:03:49Z (GMT). No. of bitstreams: 1 FontesJardim_DenisLeonardo_D.pdf: 4065886 bytes, checksum: 09542135435393259e6847f6bad0b542 (MD5) Previous issue date: 2014 / Resumo: Tradicionalmente, o modelo de desenvolvimento de drogas em onco-hematologia utiliza-se de estudos de fase I como a primeira etapa no desenvolvimento clínico de uma droga. Nesses estudos, procura-se estabelecer a dose recomendada de novos agentes e seu perfil de segurança inicial, sendo as toxicidades o principal desfecho a ser monitorado. Posteriormente, estudos de registro são conduzidos para a aprovação de novas medicações por agências regulatórias. A maioria das medicações foi historicamente desenvolvida para uma população não-selecionada de um subtipo tumoral. No entanto, recentemente, o conhecimento em onco-hematologia vem sofrendo profundas mudanças, principalmente com o advento de novas técnicas de biologia molecular que permitem um melhor conhecimento da biologia das neoplasias. Com isso, é crescente a percepção de que existem subpopulações de pacientes com alterações moleculares específicas que demandam estratégias direcionadas; também é crescente o número de novas drogas de alvo molecular em desenvolvimento. Nesse contexto, é pouco sabido se o modelo tradicional de desenvolvimento de drogas, historicamente utilizado para medicações citotóxicas e para populações não selecionadas, estaria adequado frente essas novas demandas. Neste projeto de doutorado, avaliamos a correlação dos resultados de dose e toxicidade dos estudos de fase I com desfechos semelhantes nos estudos futuros de registro de novas medicações aprovadas pelo Food and Drug Administration (FDA) em onco-hematologia, com ênfase na comparação entre drogas citotóxicas tradicionais e drogas de alvo molecular. Determinamos que em 73% das comparações os estudos de registro adotaram uma dose entre 80% e 100% daquela recomendada pelos estudos de fase I, sendo que para drogas de alvo molecular os estudos clínicos iniciais foram menos preditores da dose futuramente aprovada dos agentes. Setenta por cento das toxicidades clinicamente relevantes em estudos de registro foram ao menos citadas em estudos de fase I, havendo uma correlação positiva com um maior número de pacientes incluídos em estudos iniciais, até cerca de 60 pacientes. Apesar das diferenças entre as populações de um estudo de fase I e de registro, a análise mostrou que um dos objetivos dos estudos de fase I foi cumprido, que seria de garantir a segurança de pacientes através da determinação de dose. Também buscamos comparar a eficácia em termos de controle de neoplasias entre drogas desenvolvidas com o conceito de terapia personalizada em relação àquelas para uma população não selecionada. Através da metodologia de meta-análise, demonstramos que em estudos de registro randomizados utilizados pelo FDA, terapias consideradas personalizadas proporcionaram maiores chances de respostas antitumorais e prolongamento do tempo até progressão de doença. A análise de todos os estudos de registro (randomizados e não randomizados) também mostrou que a terapia personalizada foi um fator independente relacionado ao aumento de sobrevida global dos pacientes. Os resultados obtidos sugerem que, frente as recentes modificações no entendimento de neoplasias e desenvolvimento de drogas, o modelo tradicional de determinação de doses em estudos de fase I necessita de adaptações, principalmente para drogas de alvo molecular, e que a incorporação do conceito de terapia personalizada é benéfica e segura para pacientes / Abstract: Traditionally, phase I trials are the first step in the clinical development model of new drugs in hematology-oncology. Phase I trials aim to establish the recommended dose of new agents for further development and their initial safety profile. Toxicities are the main outcome in these studies. Subsequently, registration trials are conduct to be the basis for drug approval by regulatory agencies, including the Food and Drug Administration (FDA). The majority of new drugs were developed for an unselect histologic type of cancer. Nevertheless, new technologies led to advances in the comprehension of the molecular basis of cancers. There is a growing evidence suggesting that specific molecular subtypes of cancers need specific strategies to target their genetic drivers. Additionally, the availability of new targeted therapies is increasing. In this context, it is not known how the traditional drug development model originally developed for cytotoxic drugs and for an unselect cancer population would perform. In this PhD thesis, we compared dosing and toxicity information from phase I trials with registration trials that led to approval of new drugs for cancer treatment by the FDA, with special attention to the sub-analysis comparing targeted versus cytotoxic agents. In 73% of matched trials (phase I trial and the respective registration trial), the dose from the registration trial was within 20% of the dose recommended by the phase I. In a multivariable analysis, phase I trials of targeted agents were less predictive of the final approved dose when compared to cytotoxic agents. Of the 530 clinically relevant toxicities in later trials, 70% were described in the respective phase I. A significant relationship between increasing the number of patients in phase I (up to 60) and the ability to describe future clinically relevant toxicities was observed. Despite several differences in design and cancer population when compared to registration trials, phase I trials were able to assure safety of patients based on its dose recommendation, which is one of the major objectives of these trials. We also compared efficacy outcomes between anticancer drugs developed under a personalized strategy (biomarker-driven treatment) with drugs developed for an unselected population. In randomized registration trials (using a random-effects meta-analysis model), personalized therapy arms were associated with a higher relative response rate ratio (compared to their corresponding control arms), prolongation of progression-free survival (PFS) and trend towards longer overall survival (OS) in comparison to non-personalized trials. Analysis of experimental arms in all registration trials (randomized and non-randomized) demonstrated that personalized therapy was an independent predictor of better response rates, PFS and OS. Treatment-related mortality rate was similar for personalized and non-personalized trials. Our results suggests that the traditional dose determination model from phase I trials needs further adaptations, especially for new molecularly targeted therapies. In addition, a personalized therapy approach for development of new agents was safe and associated with improved efficacy outcomes. We believe that our results will help to implement strategies for the development of new agents for the treatment of hematologic and solid cancers / Doutorado / Clinica Medica / Doutor em Clínica Médica

京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第24548号 / 薬科博第165号 / 新制||薬科||18(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 山下 富義, 教授 髙倉 喜信, 教授 寺田 智祐 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

Identification of the unknown targets of drugs, investigative drugs and herbal ingredients is an important task in drug discovery. It can potentially help in several aspects including: (1) determination of unknown therapeutic mechanism of certain drugs and medicinal herbs, (2) prediction of drug toxicity and side effect, and (3) analysis of protein-mediated pharmacokinetic properties of drugs. Here, a computer-aided drug target search method and its validation studies are presented. / Singapore-MIT Alliance (SMA)

The human mitochondrial DNA polymerase (Pol γ) catalyzes mitochondrial DNA synthesis, and thus is essential for the integrity of the organelle. Mutations of Pol γ have been implicated in more than 150 human diseases. Reduced Pol γ activity caused by inhibition of anti-HIV drugs targeted to HIV reverse transcriptase confers major drug toxicity. To illustrate the structural basis for mtDNA replication and facilitate rational design of antiviral drugs, I have determined the crystal structure of human Pol γ holoenzyme. The structure reveals heterotrimer architecture of Pol γ holoenzyme with a monomeric catalytic subunit Pol γA, and a dimeric processivity factor Pol γB. While the polymerase and exonuclease domains in Pol γA present high structural homology with the other members of the DNA Pol I family, the spacer between the two functional domains shows a unique fold, and constitutes the subunit interface. The structure suggests a novel mechanism for Pol γ’s high processivity of DNA replication. Furthermore, the structure reveals dissimilarity in the active sites between Pol γ and HIV RT, thereby indicating an exploitable space for design of less toxic anti-HIV drugs. Interestingly, the structure shows an asymmetric subunit interaction, that is, one monomer of dimeric Pol γB primarily participates in interactions with Pol γA. To understand the roles of each Pol γB monomer, I generated a monomeric human Pol γB variant by disrupting the dimeric interface of the subunit. Comparative studies of this variant and dimeric wild-type Pol γB reveal that each monomer in the dimeric Pol γB makes a distinct contribution to processivity: one monomer (proximal to Pol γA) increases DNA binding affinity whereas the other monomer (distal to Pol γA) enhances the rate of polymerization. The pol γ holoenzyme structure also gives a rationale to establish the genotypic-phenotypic relationship of many disease-implicated mutations, especially for those located outside of the conserved pol or exo domains. Using the structure as a guide, I characterized a substitution of Pol γA residue R232 that is located at the subunit interface but far from either active sites. Kinetic analyses reveal that the mutation has no effect on intrinsic Pol γA activity, but shows functional defects in the holoenzyme, including decreased polymerase activity and increased exonuclease activity, as well as reduced discrimination between mismatched and corrected base pair. Results provide a molecular rationale for the Pol γA-R232 substitution mediated mitochondrial diseases. / text

Objetivos: descrever incidência de eventos adversos medicamentosos em crianças sob terapia intensiva, avaliar fatores de riscos e métodos de detecção. Métodos: busca ativa em registros eletrônicos e em papel, utilizando parâmetros indicativos (gatilhos). A estatística envolveu modelos de regressão linear e logística. Resultados: Foram estudados 239 pacientes, com média de idade de 67,5 meses, em 1818 dias de internação. A média de internação foi de 7,6 dias. Houve 110 eventos adversos medicamentosos provados, prováveis e possíveis, em 84 pacientes (35,1%). Observamos 138 ocorrências de gatilhos. As principais classes de medicamentos envolvidas foram: antibióticos (n = 41), diuréticos (n = 24), anticonvulsivantes (n = 23), sedativos e analgésicos (n = 17) e corticóides (n = 18). O número de drogas foi a variável mais relacionada à ocorrência de EAM. Esta última também se correlacionou com o tempo de internação (P < 0,001). A ocorrência do evento pode estar implicada no aumento de 1,5 dia de internação para cada evento. A idade inferior a 48 meses mostrou ser um risco significativo para eventos, com OR de 1,84 (intervalo de confiança IC 95% - 1,07 - 3,15, P = 0,025). O número de drogas recebidas apresentou correlação com o número de eventos (P < 0,0001). A chance de apresentar pelo menos 1 evento elevou-se linearmente à medida que o paciente recebia mais drogas. Conclusões: o uso de múltiplas drogas e a baixa idade favorecem a ocorrência de EAM, que, por sua vez, podem estar implicados no aumento do tempo de internação em UTI. A busca ativa sistematiza a abordagem do problema / Objectives: To describe incidence of adverse drug events (ADE) in children under intensive care, to avaliate risk factors and detection methods. Methods: Active search of charts and electronic patient records using indicative parameters (\"triggers\"). The statistical analysis involved linear and logistic regression. Results: 239 patients with a mean age of 67.5 months representing 1818 days of PICU hospitalization were studied. The average PICU stay was 7.6 days. There were 110 proven, probable, and possible ADEs in 84 patients (35.1%). We observed 138 instances of triggers. The major classes of drugs associated with events were: antibiotics (n = 41), diuretics (n = 24), antiseizures (n = 23), sedatives and analgesics (n = 17), and steroids (n = 18). The number of drugs administered was most related to the occurrence of ADEs. This was also related to the length of stay (p < 0.001). The occurrence of an ADE may result in an increase in the length of stay by 1.5 days per event. Patient aged less than 48 months also proved to be at significant risk for ADEs, with an odds ratio of 1.84 (confidence interval - 95% CI - 1.07 to 3.15, p = 0.025). The number of drugs administered also correlated with the number of ADEs (p < 0.0001). The chance of having at least one ADE increased linearly as the patient was administered more drugs. Conclusions: The use of multiple drugs as well as lower patient age favor the occurrence of ADEs, which in turn may result in increasing the length of PICU hospitalization. Our active search provides a systematic approach to the problem