Passive exposure of children to drugs is common, but difficult to ascertain as direct studies are in many cases not possible, and currently available indirect measures of drug exposure, such as maternal reports, are likely to be inaccurate. Novel, indirect methods to evaluate drug exposure in the uterus and early life are needed, and may provide risk estimates that can be later correlated with clinical outcomes. In the studies presented here, I have applied novel methods such as measurement of hair drug concentrations and population pharmacokinetics modeling and simulation to evaluate fetal and infant exposure to drugs and potential associated risks. Testing for methamphetamine allowed demonstration, for the first time, that it freely crosses the human placenta. In contrast, analysis of paired maternal–infant hair showed limited cocaine placental transfer, in agreement with animal models. Results of hair tests from children found in marihuana grow houses and other drug operations showed that passive exposure tends to be higher in infants, likely due to higher dependence on, and proximity to care givers. We also demonstrated the importance of measuring drug metabolites to distinguish between systemic exposure to MDMA and simple external hair contamination secondary to drug present in the home environment. Finally, we developed a population pharmacokinetics and simulation approach to accurately estimate drug excretion into breast milk. This novel technique was applied to fluoxetine and to nifurtimox. Use of our approach allowed us to define, for the first time, the limited extent to which fluoxetine and nifurtimox would be expected to cross into breast milk and estimate potential degree of exposure of breastfed infants. In summary, results presented here support the value of these novel methods for the evaluation of fetal and infant drug exposure and suggest a promising value in estimating risks to children passively exposed to drugs.

In light of the complex and highly uncertain nature of dynamical systems requiring controls, it is not surprising that reliable system models for many high performance engineering and life science applications are unavailable. In the face of such high levels of system uncertainty, robust controllers may unnecessarily sacrifice system performance whereas adaptive controllers are clearly appropriate since they can tolerate far greater system uncertainty levels to improve system performance. In this dissertation, we develop a Lyapunov-based direct adaptive and neural adaptive control framework that addresses parametric uncertainty, unstructured uncertainty, disturbance rejection, amplitude and rate saturation constraints, and digital implementation issues. Specifically, we consider the following research topics: direct adaptive control for nonlinear uncertain systems with exogenous disturbances; robust adaptive control for nonlinear uncertain systems; adaptive control for nonlinear uncertain systems with actuator amplitude and rate saturation constraints; adaptive reduced-order dynamic compensation for nonlinear uncertain systems; direct adaptive control for nonlinear matrix second-order dynamical systems with state-dependent uncertainty; adaptive control for nonnegative and compartmental dynamical systems with applications to general anesthesia; direct adaptive control of nonnegative and compartmental dynamical systems with time delay; adaptive control for nonlinear nonnegative and compartmental dynamical systems with applications to clinical pharmacology; neural network adaptive control for nonlinear nonnegative dynamical systems; passivity-based neural network adaptive output feedback control for nonlinear nonnegative dynamical systems; neural network adaptive dynamic output feedback control for nonlinear nonnegative systems using tapped delay memory units; Lyapunov-based adaptive control framework for discrete-time nonlinear systems with exogenous disturbances; direct discrete-time adaptive control with guaranteed parameter error convergence; and hybrid adaptive control for nonlinear uncertain impulsive dynamical systems.

Acute pancreatitis (AP) is a severe disease in about 20% of patients, causing hospitalization and death, mainly due to associated systemic complications. The treatment of this condition is still insufficient to control the intrinsic inflammatory process and is focused on managing the complications and symptoms of patients. Among the many factors involved in AP, the inflammatory response and oxidative stress can be highlighted. In this context, rutin is presented as a natural substance with important potential to treat AP, by considering its anti-inflammatory and antioxidant activities. The aim of this study is to investigate the pharmacological effects of rutin on experimental AP induced by L-arginine administration in mice. Adult male Swiss mice (25-30 g) were used in this study and all experiments were approved by this institution´s Ethics Committee in Animal Research (43/2012). For the induction of AP, mice received 2 injections of L-arginine (8%, 4 g/kg, i.p., with an interval of 1 h). The control group received the same volume of saline (0.9%) instead of L-arginine. Mice submitted to AP induction were treated with rutin (37.5, 75 or 150 mg/kg, p.o.) or saline (vehicle) after 24, 36, 48 and 60 h of the first injection of L-arginine. The control group was treated with vehicle at the same time points. The euthanasia occurred after 72 h of induction and was accompanied by blood and organ (pancreas, lung, liver and kidney) collection. We investigated parameters that permitted us to infer about pancreatic and systemic inflammation and evaluate serum concentrations of pancreatic enzymes, abdominal hyperalgesia and oxidative stress. In animals injected with L-arginine, it was detected the increase of inflammatory and biochemical parameters that confirmed the induction of AP, when compared with saline-injected animals. The treatment with rutin reduced the myeloperoxidase activity in pancreas (p<0.001 for 37.5, 75 or 150 mg/kg), but not in lung, reduced the pancreatic edema index (p<0.001 for 37.5 mg/kg and p<0.05 for 75 and 150 mg/kg) and the serum concentration of amylase (p<0.001 for 75 and 150 mg/kg). From these experiments, we chose the dose of 75 mg/kg for the next steps. In this way, treatment with this dose of rutin also reduced the serum lipase (p<0.001), C reactive protein (p<0.001) and interleukin-6 (p<0.001) concentrations, as well as decreased the abdominal hyperalgesia (p<0.05), when compared with Vehicle + L-arginine group after 72 h of L-arginine injection. The administration of rutin also diminished lipid peroxidation induced by L-arginine in pancreas, liver and kidney (p<0.001) and increased both the activity of catalase in pancreas (p<0.001), glutathione peroxidase in pancreas (p<0.05) and superoxide dismutase in pancreas (p<0.01) and liver (p<0.05). Besides, it decreased the expression of 3-nitrotyrosine in pancreas (p<0.05). Altogether, these results demonstrate that rutin exert anti-inflammatory, antinociceptive and antioxidant actions during AP induced by L-arginine, which are suggestive that this flavonoid is of interest for developing future studies or approaches focused on new alternatives to treat AP in humans. / A pancreatite aguda (PA) é uma doença grave em cerca de 20% dos casos, que causa hospitalização e óbito dos pacientes devido às complicações sistêmicas associadas. Seu tratamento clínico tem se mostrado insuficiente para controlar o processo inflamatório intrínseco da doença e é focado no manejo dos sintomas e complicações. Dentre os diversos fatores envolvidos na PA, destacam-se a resposta inflamatória e o estresse oxidativo. Neste contexto, a rutina, um flavonoide conhecido por suas atividades antioxidante e anti-inflamatória, apresenta-se como uma substância natural em potencial a ser utilizada no tratamento da PA. Assim, o objetivo do presente estudo foi investigar os efeitos farmacológicos da rutina em modelo de pancreatite aguda experimental induzida por L-arginina em camundongos. Foram utilizados camundongos Swiss machos adultos (25-30 g) e os procedimentos foram aprovados pelo Comitê de Ética em Pesquisa com Animais da UFS (43/2012). Para a indução da pancreatite os animais receberam duas injeções de L-arginina (8%, 4 g/kg, i.p., com intervalo de 1 h entre elas). O grupo controle recebeu duas injeções de salina (0,9%, i.p.). Os animais submetidos à indução da pancreatite foram tratados com rutina (37,5, 75 ou 150 mg/kg, v.o.) ou salina (veículo), após 24, 36, 48 e 60 h da 1° injeção de L-arginina. O grupo controle foi tratado com veículo nos mesmos tempos. A eutanásia dos animais foi realizada 72 h após a indução, com subsequente coleta de sangue e de órgãos (pâncreas, pulmão, fígado e rim). Foram avaliados parâmetros que permitiram inferir sobre o quadro inflamatório pancreático e sistêmico e avaliar as concentrações séricas de enzimas pancreáticas, a hiperalgesia abdominal e o estresse oxidativo. Os animais que receberam as injeções de L-arginina apresentaram aumento significativo dos parâmetros inflamatórios e bioquímicos preditivos de pancreatite, quando comparados aos animais que receberam salina. O tratamento com rutina reduziu a atividade de mieloperoxidase no pâncreas (p<0,001 para 37,5, 75 ou 150 mg/kg), mas não no pulmão, reduziu o índice de edema pancreático (p<0,001 para 37,5 mg/kg e p<0,05 para 75 e 150 mg/kg) e a concentração sérica de amilase (p<0,001 para 75 e 150 mg/kg). A partir destes resultados a dose de 75 mg/kg foi escolhida para ser utilizada nos experimentos posteriores. O tratamento com esta dose de rutina também diminuiu as concentrações séricas de lipase (p<0,001), proteína C reativa (p<0,001) e de interleucina 6 (p<0,001), bem como reduziu a hiperalgesia abdominal (p<0,05), após 72 h da injeção de L-arginina, quando comparados ao grupo L-arginina + Veículo. O tratamento com rutina (75 mg/kg) também reduziu a peroxidação lipídica induzida pela L-arginina em pâncreas, fígado e rim (p<0,001) e aumentou a atividade de catalase pancreática (p<0,001),de glutationa peroxidase (p<0,05) de superóxido dismutase no pâncreas (p<0,01) e no fígado (p<0,05), além de diminuir a expressão de 3-nitrotirosina no pâncreas (p<0,05). Estes resultados evidenciam que a rutina exerce efeito anti-inflamatório, antinociceptivo e antioxidante durante a PA induzida por L-arginina, os quais sugerem que este flavonoide seja de interesse para abordagens ou estudos futuros objetivando novas alternativas no tratamento da PA em humanos.

<p>  </p> <p>Polypharmacy in older adults presents several challenges, such as suboptimal therapeutic outcomes and increased adverse effects. Deprescribing, a clinically supervised process of decreasing dosage or stopping the medication when risks outweigh benefits, has emerged as one possible solution to these problems. However, the literature describing deprescribing intervention frameworks is heterogenous regarding targeted medications to deprescribe, population characteristics, clinical settings, and measured outcomes. This dissertation utilizes Linsky et al.'s deprescribing conceptual model, which details factors influencing decisions regarding initiating deprescribing interventions and their direct impact on the process. </p> <p>This dissertation utilizes a multimethod approach to investigate factors that facilitate and improve the deprescribing of anticholinergic medications for older adults, addressing gaps in this population's anticholinergic medication use. The three studies included in this dissertation provide a comprehensive understanding of deprescribing anticholinergic medications for this population, each contributing unique insights and results. </p> <p>The first study explores the feasibility of in-person and remote Home Medication Inventory Method (HMIM) approaches to evaluate over-the-counter (OTC) and prescription medication possession and use, including anticholinergics. Results demonstrate that both methods can accurately assess anticholinergic medication usage patterns, providing healthcare providers with reproducible methods and detailed medication profiles to make informed deprescribing decisions based on complete medication lists.</p> <p>The second study examined the intertwined roles of social determinants of health and health beliefs in predicting older adults' self-reported deprescribing behaviors, proposing the Deprescribing Health Belief Model (DeRx-HBM) framework that can be utilized for these efforts. These results emphasize the importance of considering these elements when creating a patient-centric and culturally sensitive intervention since they significantly shape deprescribing behaviors.</p> <p>In the third study, we explored the use of a symptom-specific scale for measuring the symptom burden in older adults during the deprescribing of anticholinergic medications prescribed for urinary incontinence, depression, and pain management. This research introduces a validated scale for assessing anticholinergic symptom burden prior to, throughout, and following the deprescribing attempt. The implementation of this scale has the potential to enhance the reproducibility and standardization of deprescribing decisions. Furthermore, it can improve communication between healthcare professionals and patients, as well as monitor the effectiveness of interventions during and after the deprescribing process.</p> <p>Collectively, these studies provide invaluable insights into factors influencing deprescribing decisions, obstacles to implementing deprescribing practices, and potential strategies to optimize medication management in older adults. The major takeaway from these studies is that addressing these factors leads to more informed decisions among healthcare professionals and patients - potentially leading to improved patient outcomes, ensure the ongoing effectiveness of deprescribing initiatives among older adults, and the promotion of health equity throughout the deprescribing process.</p>

<p dir="ltr"><b>Background</b></p><p dir="ltr">Heart failure (HF) is a chronic clinical syndrome characterized by symptoms including breathlessness, fatigue, swelling of the ankles, and signs such as edema pulmonary crackles etc. During HF, pathogenic mechanisms including hemodynamic overload, ventricular remodeling, aberrant calcium handling, excessive neurohormonal stimulation contribute to the worsening and progression of the condition. Ventricular arrhythmias are the common cause of sudden cardiac death (SCD) in HF patients.</p><p dir="ltr">Hyperactivation of the sympathetic nervous system (SNS), a characteristic of HF, causes an increase in circulating catecholamines which becomes detrimental to-adrenergic receptors (-AR) leading to signaling dysfunction, and decrease in contractility and the ionotropic reserve. Expression of calcium/calmodulin-dependent protein kinase II (CaMKII), a downstream effector of-AR and a key regulator of calcium homeostasis, has been shown to be enhanced in HF. CaMKII-mediated mechanisms have been demonstrated to contribute to cardiac remodeling, arrhythmias by pathological regulation of ion channels, and contractile dysfunction.</p><p dir="ltr">The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the voltage-gated potassium channel that conduct the rapid component of the delayed rectifier potassium current, <i>I</i>_Kr. The gating kinetics of <i>I</i>_Krmakes it a crucial determinant of the duration of the plateau phase of atrial and ventricular action potential (AP). Reduced <i>I</i>_Kr density due to loss-of-function mutations or pharmacological blockage of hERG channels precipitate arrhythmias. Downregulation of <i>I</i>_Kr density and protein have been reported in HF. Recent studies suggest that microRNAs (miRNAs) are involved in pathological downregulation of hERG.</p><p dir="ltr">miRNA are small non-coding RNAs of approximately 22 nucleotides in length that function as gene expression regulatory elements by repression translation. Aberrant miRNA expression has associated with cancer, cardiovascular, autoimmune, and inflammatory disorders.</p><p dir="ltr"><b>Objective</b></p><p dir="ltr">The overarching objective of this study is to investigate the mechanisms of CaMKII-mediated regulation of hERG function, including assessment of an interplay with miR-362-3p during sustained β-AR stimulation. In Specific Aim 1, the effect of CaMKII activation through sustained β-AR stimulation on hERG function and miR-362-3p expression will be assessed. The mechanism of miR-362-3p upregulation will be evaluated in Specific Aim 2, and in Specific Aim 3, the interactome of miR-362-3p and binding sites will be characterized and predicted, respectively.</p><p dir="ltr"><b>Methods</b></p><p dir="ltr">Whole-cell, voltage clamp electrophysiology experiments were performed in HEK 293 cells stably expressing hERG (hERG-HEK) and both hERG and wild-type CaMKIIδ<br>(hERG/CaMKII-HEK) following treatment with isoproterenol for 48 hours, and after transfection with miR-362-3p. The effect of CaMKII activation on miR-362-3p was assessed using real-time quantitative polymerase chain reaction (RT-qPCR). Total RNA was isolated 48 hours after isoproterenol treatment and the TaqMan assay was used to reverse transcribe and analyze miR-362-3p expression. Cells were transfected with cJun siRNA and precursor miR-362-3p to assess the role of cJun miR-362-3p upregulation during sustained β-AR stimulation with isoproterenol. The interactome of miR-362-3p was assessed in both cell lines using enhanced crosslinking immunoprecipitation (eCLIP) assay. miR-362-3p binding sites were predicted using RNAStructure Duplexfold after identification of miR-362-3p chimeric molecules from eCLIP experiment. Interaction analysis was performed using GeneMania in Cytoscape to identify genes that were potentially downregulated by miR-362-3p and been reported to interact with hERG.</p><p dir="ltr"><b>Results</b></p><p dir="ltr">In Specific Aim 1, the effect of sustained β-AR stimulation on hERG currents and endogenous miR-362-3p was assessed in hERG-HEK and hERG/CaMKII-HEK cells. Using whole-cell voltage clamp electrophysiology, we demonstrated that 48 hours treatment with 100 nM isoproterenol reduced hERG currents in hERG/CaMKII-HEK cells (p = 0.032) but had no effect on the voltage dependence of activation (p = 0.61) relative to control vehicle. Isoproterenol treatment for 48 hours, however, had no effect on hERG currents (p = 0.58) and the voltage dependence of activation (p = 0.99) in hERG-HEK cells. The effect of sustained isoproterenol treatment on miR-362-3p was also assessed using RT-qPCR. In hERG/CaMKII cells, 48 hours isoproterenol treatment increased miR-362-3p expression (2.3 folds; p = 0.038) relative to control vehicle. hERG/CaMKII-HEK cells were also treated with 500 nM KN-93 or its inactive analogue, KN-92, in an attempt to reverse CaMKII effect on miR-362-3p expression. Treatment with KN-93 decreased miR-362-3p expression (0.5-fold; p = 0.002) relative KN-92 treatment. Isoproterenol treatment had no effect on miR-362-3p expression in hERG-HEK cells (p = 0.38).</p><p dir="ltr">The regulatory mechanism of miR-362-3p expression was evaluated in Specific Aim 2. The role of an activator protein-1 (AP-1)-like sequence located at 98 base pairs upstream of miR-362-3p transcription start site was probed using siRNA inhibition of cJun, a central protein of the AP-1 complex, and deletion of the site sequence. The effect of exogenous miR-362-3p on hERG currents were first assessed. Precursor miR-362-3p decreased hERG currents (p = 0.003) compared to control plasmid. The effect of CaMKII overexpression was also assessed on exogenous miR-363-3p expression. Isoproterenol treatment in hERG/CaMKII-HEK cells transfected with precursor miR-362-3p increased mature miR-362-3p expression (0.029) compared to control vehicle treatment. Inhibition of cJun inhibition with cJun-specific siRNA decreased mature miR-362-3p expression (0.5-fold; p = 0.027) compared to scramble siRNA in hERG-HEK cells. In hERG-HEK cells transfected with mutated precursor miR-362-3p (AP-1-like site deleted), cJun inhibition with siRNA had no effect on miR-362-3p expression (p = 0.40).</p><p dir="ltr">The focus of Specific Aim 3 was to characterize the interactome of miR-362-3p as well as predict the miRNA response element (MRE) of its target mRNAs using enhanced crosslinking immunoprecipitation. A network analysis was also performed to identify miR-362-3p targets that have been reported to interact with hERG. Approximately 23% of miR-362-3p mRNA targets from the eCLIP assay have also been catalogued in miRNA database, TargetScanHuman, as miR-362-3p targets. miR-362-3p chimeric molecules with 853 unique targets, of which 75 were identified to interact with hERG through the network analysis. Four unique chimeric molecules between miR-362-3p and hERG mRNA were identified, but the interactions were non-canonical (located in the coding sequence of hERG and outside the seed region of miR-362-3p). Thirty five of the 75 miR-362-3p targets that were identified to interact had a chimeric read ≥ 3, a cutoff number indicating non-random chimeric formation. Using RNAStructure DuplexFold, miR-362-3p was predicted to form canonical binding with 12 of 35 mRNA targets. HSPA4, a heat shock protein involved in the maturation and trafficking of hERG, was identified in a canonical interaction (8-mer) with miR-362-3p.</p><p dir="ltr"><b>Conclusion</b>:</p><p dir="ltr">Sustained β-AR stimulation increases miR-362-3p expression and decreases hERG currents in CaMKII overexpressing cells. cJun mediates miR-362-3p upregulation by interacting with an AP-1-like sequence upstream of miR-362-3p transcription start site. Pathological regulation of <i>I</i>_Kr by CaMKII mediated by miR-362-3p during sustained-AR may contribute to increased risk of arrhythmias in states of increase catecholaminergic activity, such as HF.</p>

Komplette pharmakologische Unterbrechung des Baroreflexes mittels eines Ganglienblockers führt zu einer starken Zunahme der Wirkung vasoaktiver Substanzen auf den Blutdruck. Eine ähnliche Überempfindlichkeit gegenüber vasoaktiven Substanzen ist auch bei Erkrankungen zu beobachten, die mit Schädigungen des afferenten oder des efferenten Schenkels des Baroreflexes einhergehen. Variabilität der Baroreflexfunktion innerhalb der Population trägt somit in erheblichem Umfang zur Variabilität des Ansprechens auf vasoaktive Substanzen bei. Durch Vergleich der Wirkung kreislaufwirksamer Substanzen oder physiologischer Interventionen vor und während Ganglienblockade können zentrale und periphere Effekte voneinander unterschieden werden. Mit dieser Methode können Änderungen der vaskulären Sensitivität und der Pufferfunktion des Baroreflexes bei Krankheitszuständen charakterisiert werden. / Complete pharmacological interruption of the baroreflex using ganglionic blockade is associated with a profound increase in the blood pressure response to vasoactive substances. Similar hypersensitivity to vasoactive substances can be observed in disorders that involve the afferent arc or the efferent arc of the baroreflex. Therefore, interindividual variability in baroreflex function contributes substantially to the variability in the responsiveness to vasoactive substances. Comparison of the response to cardiovascular medications before and during ganglionic blockade can be used to dissect central and peripheral effects. This approach is also useful to characterize changes in vascular sensitivity and in baroreflex buffering function in diseases.

En inhibant la formation de caillots dans le sang, les médicaments antiplaquettaires diminuent de façon importante le risque d’événements ischémiques aigus. Cependant, une sous-population de patients souffrant de maladie coronarienne présente une inhibition inadéquate de la fonction plaquettaire malgré la prise quotidienne d’acide acétylsalicylique (AAS). Le premier volet de cette thèse démontre qu’une régénération plaquettaire accélérée pourrait expliquer en partie la variabilité dans la persistance de l’effet antiplaquettaire de l’AAS chez certains sujets souffrant de maladie coronarienne. Ces données suggèrent qu’une augmentation de la fréquence d’administration d’AAS d’une à deux fois par jour pourrait être bénéfique chez ces sujets. Des méta-analyses ont suggéré qu’une réponse plaquettaire inadéquate à l’AAS pourrait augmenter le risque d’événements ischémiques récurrents. La nature rétrospective de ces analyses ne permet pas d’établir la causalité. Dans le deuxième volet de cette thèse, les résultats d’une étude prospective visant à comparer la pertinence clinique de 6 tests de fonction plaquettaire fréquemment utilisés pour évaluer la réponse plaquettaire à l’AAS est présentée. Les résultats démontrent qu’aucun des tests de fonction plaquettaire couramment employés ne prédit la survenue d’événements ischémiques aigus chez des patients souffrant de maladie coronarienne stable. Toutefois, la cessation de la prise d’AAS est un prédicteur important d’événements thrombotiques. La cessation de médicaments antiplaquettaires a souvent été associée à la survenue d’événements thrombotiques dans les jours suivant l’interruption. À savoir si la survenue de ces événements est attribuable uniquement au retrait d’un médicament protecteur ou plutôt à une sensibilisation plaquettaire, constitue un débat d’actualité. Dans le troisième volet de cette thèse, des données sont présentées démontrant que la cessation de clopidogrel après la période recommandée par les lignes directrices actuelles provoque une sensibilisation des plaquettes nouvellement formées aux stimuli plaquettaires physiologiques. Ces résultats encouragent la recherche sur différentes modalités pour atténuer le risque thrombotique accru chez ces patients souffrant de maladie coronarienne. En conclusion, cet ouvrage présente des études visant à identifier les sous-populations de patients qui sont plus à risque de complications cardiovasculaires récurrentes. Dans ce contexte, la personnalisation de traitement est une avenue thérapeutique prometteuse, où chaque patient pourra recevoir un traitement ciblé en fonction de ses besoins et de ses contre-indications. Ce changement de paradigme d’une thérapie empirique issue d’études de grande envergure sur des données populationnelles à une thérapie ajustée aux besoins individuels représente un vaste champ de recherche, où la majorité des découvertes sont à faire. / By inhibiting the formation of blood clots, antiplatelet drugs significantly reduce the risk of acute ischemic events. However, a subpopulation of patients suffering from coronary artery disease presents with an inadequate inhibition of platelet function despite taking acetylsalicylic acid (ASA) daily. The first part of this thesis demonstrates that accelerated platelet turnover could partly explain the variability in the persistence of the antiplatelet effect of ASA in some coronary artery disease patients. These results suggest that increasing the frequency of administration of ASA from once to twice daily may be beneficial in selected patients. Meta-analyses have suggested that an inadequate platelet response to ASA may increase the risk of recurrent ischemic events. The retrospective nature of these analyses forbids the inference of causality. In the second part of this thesis, the results of a prospective study comparing the clinical relevance of 6 platelet function tests commonly used to assess platelet response to ASA are presented. The results show that none of the commonly used platelet function tests predict the occurrence of acute ischemic events in stable coronary artery disease patients. However, discontinuation of ASA is an important predictor of thrombotic events. Discontinuation of antiplatelet drugs has often been associated with thrombotic events in the days following cessation. If the occurrence of these events is due solely to the withdrawal of a protective drug or rather platelet sensitization is a topic of some debate. In the third part of this thesis, data are presented demonstrating that clopidogrel discontinuation, after the period recommended by current guidelines, leads to sensitization of newly formed platelets to physiological platelet stimuli. These results encourage research on different ways to mitigate the increased risk of thrombosis in coronary artery disease patients scheduled to discontinue clopidogrel therapy. In conclusion, this dissertation presents studies aiming to identify subpopulations of patients who are at increased risk of recurrent cardiovascular events. In this context, the personalization of treatment is a promising therapeutic avenue, where each patient can receive a targeted therapy according to his needs and contraindications. This shift in paradigm from empirical therapy based on population data retrieved from large clinical studies to therapy tailored to individual needs opens a vast field of research, where the majority of discoveries remain to be made.

Entre as estratégias de fotoproteção encontra-se a inibição da formação e/ou o seqüestro de radicais livres e espécies reativas de oxigênio geradas em conseqüência da exposição à radiação UV, mediante aplicação tópica de antioxidantes. No presente trabalho avaliou-se a permeação cutânea e o efeito da aplicação tópica de um extrato de Pothomorphe umbellata nos efeitos da exposição aguda e crônica à radiação ultravioleta, na pele de camundongos sem pêlo. No estudo de permeação cutânea foram testadas três formulações (gel, gel-creme e creme) contendo o princípio ativo do extrato (4-nerolidilcatecol) isolado. Também foram testadas duas formulações (gel, e gel-creme) contendo o extrato hidroalcoólico liofilizado de Pothomorphe umbellata, quanto à permeação do princípio ativo 4-nerolidilcatecol. A formulação gel tanto para o princípio ativo isolado, quanto para o princípio ativo presente no extrato, apresentou o melhor desempenho, sendo o gel o veículo escolhido para preparação da formulação utilizada nos ensaios de exposição crônica e aguda à radiação ultravioleta. Nos estudos de exposição aguda à radiação UVB não foram observadas alterações significativas nos níveis de ácido ascórbico e na atividade enzimática, mas sim uma redução de 40% (p<0,01) na concentração de &#945;-tocoferol na pele do grupo de. camundongos sem pêlo, controle irradiado. No grupo tratado com P. umbellata, o &#945;-tocoferol foi totalmente preservado, quando comparado aos níveis encontrados no grupo controle não irradiado (&#8776;100%, p>0,05). No estudo de exposição crônica dos camundongos sem pêlo à radiação ultravioleta, os grupos irradiados que não receberam tratamento com gel de P. umbellata apresentaram a pele fotoenvelhecida. O grupo irradiado e tratado com o gel de Pothomorphe umbellata não apresentou diferença significativa em relação ao grupo controle não irradiado, o que demostra que o extrato de Pothomorphe umbellata pode ser empregado com sucesso como agente foto protetor tópico no fotoenvelhecimento da pele. / Topical administration of antioxidants provides an efficient way to enrich the endogenous antioxidant system and thus may be a successful strategy for diminishing ultraviolet radiation-mediated oxidative damage in the skin. The Brazilian Flora is rich in medicinal plants with a high potential to provide these antioxidant substances. Crude dried root ethanolic extracts of Pothomorphe umbellata, from the piperaceae family, demonstrated a significant activity in the prevention of in vitro spontaneous brain lipid peroxidation. This activity was attributed to 4-nerolidylcathecol, a compound isolated from the hexane extracts of roots and leaves of P. umbellata. In this work we evaluated the influence of topical application of P. umbellata root extract gel, containing 0,1% of 4-nerolidylcathecol, on the antioxidant network in ultraviolet-induced oxidative damage in hairless mouse skin. In this study we evaluated the influence of three different formulations (gel, gel-emulsion and emulsion) on the percutaneous absorption of 4-nerolidylcathecol, an antioxidant compound isolated from Pothomorphe umbellata root extracts. Also the absorption of the isolated 4-nerolidylcathecol was compared with its absorption when dried Pothomorphe umbellata root ethanolic extract was incorporated in gel and gel-emulsion formulations. The 4-nerolidylcathecolgel formulation presented the higher rate of penetration, leading to higher dry drug levels in the tissue.4-nerolidylcathecol was also absorbed in biological conditions and was stable when exposed to UV-irradiation. The UV-irradiation had no influence on ascorbic acid levels, or on the antioxidant enzymes activities, but topical P. umbellata treatment protected &#945;-tocopherol from depletion after UV-irradiation. After UV-irradiation &#945;-tocopherol concentration decreased significantly (&#8776;40%, p<0.01) in irradiated control groups, while in the P. umbellata treated group, a-tocopherol was totally preserved (&#8776;100%, p>0.05). We also tested the extract activity on animals chronically exposed to UV-radiation. The extract was able to prevent photoaging of the irradiated animals skin. These data demonstrate that P. umbellata may successfully employed as a topical photoprotective agent.

A circulação extracorpórea com hipotermia (CEC-H) é um procedimento comumente utilizado em cirurgias cardíacas, que representa um fator de risco para o paciente por promover extensa hemodiluição e profundas alterações fisiológicas. Nestas cirurgias, utiliza-se a cefuroxima como antimicrobiano para profilaxia de infecções, estando sua concentração inibitória mínima (CIM90) na faixa de 4 a 16 &#181;g/mL dependendo da espécie e cepa bacteriana. Vários esquemas posológicos tem sido propostos para a profilaxia com este antimicrobiano. Assim, o objetivo do presente estudo foi investigar a farmacocinética e a disponibilidade sistêmica da cefuroxima, administrada I.V., bolus, na dose de 1,5g a 17 pacientes submetidos à cirurgia cardíaca com ou sem CEC-H. Desenvolveu-se método analítico simples seletivo e sensível em CLAE-UV para determinar a cefuroxima no plasma e tecido subcutâneo destes pacientes. Os resultados evidenciaram que independente das alterações causadas pela CEC-H, obtiveram-se baixas concentrações plasmáticas, inferiores ao CIM90, a partir da 9a hora após a administração da medicação nos dois grupos de pacientes investigados. Esta baixa disponibilidade sistêmica da cefuroxima após administração de 1,5 g pode favorecer o desenvolvimento de infecções pós-cirúrgicas e o desenvolvimento de cepas bacterianas resistentes. Por outro lado, a disposição cinética da cefuroxima foi alterada pela CEC-H, evidenciando-se ligeiro mas significativo prolongamento da meia vida biológica e redução da depuração plasmática nos pacientes submetidos a este procedimento. A ausência de alterações no volume de distribuição está de acordo com a penetração do antibiótico no tecido, uma vez que a quantidade de cefuroxima presente no subcutâneo foi comparável em ambos os grupos de pacientes investigados. Os dados obtidos permitem recomendar mudanças no regime posológico para manter níveis plasmáticos adequados e garantir a profilaxia com cefuroxima. / Cardiopulmonary bypass and hypothermia (HCPB) is a procedure commonly used during heart surgery, representing a risk factor for the patient by promoting extensive hemodilution and profound physiological changes. Cefuroxime is used for the prophylaxis of infection after heart surgery and its minimum inhibitory concentration (MIC90) may vary from 4 to 16 &#181;g/mL depending on the bacterial species and strain. Several dose schemes have been suggested for prophylaxis with this antimicrobial agent. Thus, the objective of the present study was to assess in a comparative manner the systemic availability of cefuroxime administered intravascularly at the dose of 1.5 g in bolus to 17 patients submitted to heart surgery with or without HCPB. An improved, simple, selective and sensitive micromethod based on HPLC-UV is described to determine cefuroxime in plasma and fat tissue. Despite the differences recorded during the study period as a consequence of HCPB, antibiotic concentrations lower than MIC90 were obtained as early as after the 9th h for the surgical patients of the two groups of patients investigated. Thus, the low systemic availability of cefuroxime after the administration of a 1.5 g dose may be the factor responsible for postoperative infections and may favor the development of resistant bacterial strains. By the other hand, cefuroxime kinetic disposition was altered by HCPB showing a slight prolongation of biological half-life e reduction of plasma clearance. Unchanged apparent volume of distribution was according antibiotic tissue penetration since in both groups of patients the amount of cefuroxime obtained was comparable. The data obtained permit us to recommend a change in the dose scheme in order to maintain adequate plasma levels of the drug and thus guarantee prophylaxis with cefuroxime.

Entre as estratégias de fotoproteção encontra-se a inibição da formação e/ou o seqüestro de radicais livres e espécies reativas de oxigênio geradas em conseqüência da exposição à radiação UV, mediante aplicação tópica de antioxidantes. No presente trabalho avaliou-se a permeação cutânea e o efeito da aplicação tópica de um extrato de Pothomorphe umbellata nos efeitos da exposição aguda e crônica à radiação ultravioleta, na pele de camundongos sem pêlo. No estudo de permeação cutânea foram testadas três formulações (gel, gel-creme e creme) contendo o princípio ativo do extrato (4-nerolidilcatecol) isolado. Também foram testadas duas formulações (gel, e gel-creme) contendo o extrato hidroalcoólico liofilizado de Pothomorphe umbellata, quanto à permeação do princípio ativo 4-nerolidilcatecol. A formulação gel tanto para o princípio ativo isolado, quanto para o princípio ativo presente no extrato, apresentou o melhor desempenho, sendo o gel o veículo escolhido para preparação da formulação utilizada nos ensaios de exposição crônica e aguda à radiação ultravioleta. Nos estudos de exposição aguda à radiação UVB não foram observadas alterações significativas nos níveis de ácido ascórbico e na atividade enzimática, mas sim uma redução de 40% (p<0,01) na concentração de &#945;-tocoferol na pele do grupo de. camundongos sem pêlo, controle irradiado. No grupo tratado com P. umbellata, o &#945;-tocoferol foi totalmente preservado, quando comparado aos níveis encontrados no grupo controle não irradiado (&#8776;100%, p>0,05). No estudo de exposição crônica dos camundongos sem pêlo à radiação ultravioleta, os grupos irradiados que não receberam tratamento com gel de P. umbellata apresentaram a pele fotoenvelhecida. O grupo irradiado e tratado com o gel de Pothomorphe umbellata não apresentou diferença significativa em relação ao grupo controle não irradiado, o que demostra que o extrato de Pothomorphe umbellata pode ser empregado com sucesso como agente foto protetor tópico no fotoenvelhecimento da pele. / Topical administration of antioxidants provides an efficient way to enrich the endogenous antioxidant system and thus may be a successful strategy for diminishing ultraviolet radiation-mediated oxidative damage in the skin. The Brazilian Flora is rich in medicinal plants with a high potential to provide these antioxidant substances. Crude dried root ethanolic extracts of Pothomorphe umbellata, from the piperaceae family, demonstrated a significant activity in the prevention of in vitro spontaneous brain lipid peroxidation. This activity was attributed to 4-nerolidylcathecol, a compound isolated from the hexane extracts of roots and leaves of P. umbellata. In this work we evaluated the influence of topical application of P. umbellata root extract gel, containing 0,1% of 4-nerolidylcathecol, on the antioxidant network in ultraviolet-induced oxidative damage in hairless mouse skin. In this study we evaluated the influence of three different formulations (gel, gel-emulsion and emulsion) on the percutaneous absorption of 4-nerolidylcathecol, an antioxidant compound isolated from Pothomorphe umbellata root extracts. Also the absorption of the isolated 4-nerolidylcathecol was compared with its absorption when dried Pothomorphe umbellata root ethanolic extract was incorporated in gel and gel-emulsion formulations. The 4-nerolidylcathecolgel formulation presented the higher rate of penetration, leading to higher dry drug levels in the tissue.4-nerolidylcathecol was also absorbed in biological conditions and was stable when exposed to UV-irradiation. The UV-irradiation had no influence on ascorbic acid levels, or on the antioxidant enzymes activities, but topical P. umbellata treatment protected &#945;-tocopherol from depletion after UV-irradiation. After UV-irradiation &#945;-tocopherol concentration decreased significantly (&#8776;40%, p<0.01) in irradiated control groups, while in the P. umbellata treated group, a-tocopherol was totally preserved (&#8776;100%, p>0.05). We also tested the extract activity on animals chronically exposed to UV-radiation. The extract was able to prevent photoaging of the irradiated animals skin. These data demonstrate that P. umbellata may successfully employed as a topical photoprotective agent.