VictorJuiz/thesis huggingface dataset:
Mechanisms of Drug-induced Oxidative Stress in the Hepatocyte Inflammation Model
Keywords: Inflammation, Oxidative Stress, Hepatocytes

Drug induced idiosyncratic agranulocytosis has been attributed to oxidation by hypochlorite formed by bone marrow myeloperoxidase (MPO). Idiosyncratic liver toxicity could also involve drug oxidative activation by cytochrome P450 (in hepatocytes) or MPO (in Kupffer cells or infiltrating neutrophil/macrophages). Such drug reactive metabolites could cause cytotoxicity or release “danger signals” that attract immune cells which release H2O2 resulting from nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) activation. In vivo animal studies have shown that low level tissue inflammation markedly increased drug-induced tissue toxicity which was prevented by immune cell inhibitors and increased by cell activators. It is suggested that idiosyncratic drugs are much more toxic, taken during symptomless inflammation periods. Furthermore, it is hypothesized that hepatocytes are much more susceptible to some idiosyncratic drugs if they are exposed to hydrogen peroxide (H2O2)/myeloperoxidase or cytokines released by inflammatory cells. A hepatocyte inflammation model, in which hepatocytes were exposed to a non-toxic H2O2 generating system and peroxidase, was found to be much more vulnerable to four idiosyncratic drugs e.g., troglitazone, isoniazid, hydralazine and amodiaquine. The molecular cytotoxic mechanisms for this marked increase in cytotoxicity were investigated as follows: 1) A P450/H2O2-catalyzed pathway not involving oxidative stress e.g., hydralazine and isoniazid; 2) A P450/H2O2-catalyzed oxidative stress-mediated cytotoxic pathway e.g., hydrazine (an isoniazid metabolite) and hydralazine; and 3) A peroxidase/H2O2-catalyzed oxidative stress-mediated cytotoxic pathway e.g,, hydralazine, amodiaquine and troglitazone. Before cytotoxicity ensued, GSH oxidation, protein carbonyl formation and often lipid peroxidation occurred followed by a decrease in mitochondrial membrane potential indicating that oxidative stress was the molecular mechanism of cytotoxicity. In summary, a H2O2-enhanced hepatocyte system in the presence and absence of peroxidase may prove useful for a more robust screening of drugs for assessing the enhanced drug toxicity risk associated with taking drugs during periods of inflammation.
Application of Pharmacokinetic Theory to Examine Roles of Transporters and Enzymes in Intestinal and Hepatic Drug Disposition
Keywords: pharmacokinetics
transporter
enzyme
drug disposition
PBPK modeling
drug first-pass removal
Caco-2
liver perfusion

The interplay of transporters and enzymes and their transporter-enzyme was examined in Caco-2 cell monolayer and recirculating perfused rat liver preprations via both theoretical and experimental approaches. First, a Caco-2 catenary model that consisted of the apical, cellular, basolateral compartments and encompasses influx, efflux transporters and enzymes was shown to be superior to the single barrier approach for data interpretation on transporter- and enzyme- mediated processes. The kinetics of baicalein, a flavonoid that undergoes glucuronidation and sulfation, were found to be described better by the catenary model for the complex kinetics of substrate inhibition in metabolism. Second, estradiol-17beta-D-glucuronide (E217G), a protypic substrate of Oatp1a1, 1a4, and 1b2 and Mrp2 that underwent futile cycling with its 3-sulfate metabolite (E23S17G) via estrogen sulfotransferase (Sult1e1) and arylsulfatase C, was examined in the perfused rat liver preparation. Solutions of the AUC and clearances were solved to relate the intrinsic clearances of transporters and enzymes to understand how these affected the apparent clearances in the presence of futile cycling. Transporters and enzymes were perturbed experimentally by the intraportal injection of CC531 colon carcinoma cells for tumor induction in Wag/Rij rat livers. The protein expression of Oatp1a1 and Oatp1b2 were reduced to half whereas Sult1e1 was increased by 40% with tumor development versus the sham-operated control. These data were well predicted by the physiologically-based liver model, showing the impact of increased sulfation intrinsic clearance but not the decreased influx clearance. The TR- (Mrp2 mutant) rat model was used to examine how the absence of Mrp2 for biliary secretion of both E217G and E23S17G affected futile cycling. Absence of Mrp2 was found to result in a pseudo steady-state and reduction of the total, excretion, and metabolic clearances in the liver. The work shed new insight on the interplay between enzymes and transporters and how kinetic processes mediated by enzymes or efflux transporters affected futile cycling.
Methods to Predict Individualized Combined Benefit/Harm Patient Profiles for Warfarin
Keywords: warfarin
risk assessment
methods

Warfarin has well-proven benefit (stroke prevention) but an associated increase in harm (major bleeding) in patients with atrial fibrillation (AF). Current clinical prediction rules (CPRs) are limited in that stroke CPRs predict only the probabilities of “stroke” and “no stroke” and bleeding CPRs predict only “bleed” and “no bleed” despite the fact that outcomes actually include combinations of these four groups. The study objective was to evaluate methods to create a CPR that calculates individual patient probabilities of warfarin’s four combined benefit/harm outcome groups: i) no stroke/no bleed; ii) no stroke/bleed; iii) stroke/no bleed; iv) stroke/bleed. Methods: Patient-level data were analyzed from a randomized controlled trial database (n=9,155) and an observational anticoagulant clinic database (n=5,475) from start of trial or time of AF diagnosis respectively (baseline), until end of follow-up. Patients were stratified into the four groups based on their outcomes during follow-up. Due to high mortality in both datasets, death was included as an outcome. Decision tree modeling and polytomous logistic regression (PLR) were conducted to identify baseline patient factors predicting each outcome group. Results: Based on a literature review of recent high quality RCTs, benefit and harm are reported separately and not at a more individualized level than subgroup analysis. In this individualized combined benefit/harm analysis, both PLR and decision tree modeling identified predictors of no stroke/no bleed, no stroke/bleed, stroke/no bleed and death without a prior stroke or bleed. PLR results predicted probabilities of combined benefit/harm outcomes for every patient but required detailed computation. However, results could potentially be converted into automated form for ease of use. Decision trees provided a visual algorithm approach to risk assessment but did not i) predict the probability of warfarin’s combined benefit/harm outcomes based on all predictors simultaneously, ii) predict the probability of these outcomes for every patient or iii) provide statistical parameters of predictive value (odds ratios). Conclusions: The PLR technique could be used to predict patient probabilities of combined benefit/harm outcomes with warfarin. The study results require validation, preferably prospectively, in other cohorts. If validated, this approach should be tested to determine if it aids patient decision-making.
Coronary Artery Outcome in Kawasaki Disease: The Role of Matrix Metalloproteinase-9 and Therapeutic Modulation of Its Activity
Keywords: vasculitis
matrix metalloproteinase
Kawasaki disease
tumour necrosis factor

Kawasaki disease (KD) is a multisystem vasculitis that results in localized coronary artery elastin breakdown and aneurysm formation. It is the leading cause of acquired heart disease of children in North America. Despite conventional treatment, a significant proportion of patients continue to develop coronary sequelae. The mechanisms of arterial aneurysm formation in KD are not known. Using a murine model of KD, Lactobacillus casei cell wall extract-induced coronary arteritis, the processes leading to coronary aneurysm formation were examined. Vessel damage occurred as a result of the increased enzymatic activity of the elastase, matrix metalloproteinase (MMP)-9. MMP-9 protein and activity levels were elevated in the heart post-disease induction. Expression and activity were specific for and localized to inflamed coronary arteries. The pro-inflammatory cytokine, tumour necrosis factor (TNF)-α, was required for increasing local MMP-9 expression. Importantly, MMP-9-deficient animals had a significantly reduced incidence of elastin breakdown. Furthermore, in a cohort of KD patients, serum MMP-9 did not correlate with coronary outcome, highlighting the importance of local expression of this elastase. Intravenous immunoglobulin (IVIG) and aspirin/salicylate are therapeutic agents in current use for the treatment of KD, though their exact mechanisms of action in KD are not known. The biologic effects of IVIG and salicylate on critical stages of disease development were examined. IVIG and salicylate had differential effects on TNF-α expression, with therapeutic concentrations of IVIG inhibiting, and salicylate inducing, TNF-α expression leading to an indirect modulation of MMP-9 expression. Interestingly, TNF-α expression and MMP-9 activity were both directly inhibited by the metal-chelating drug doxycycline. Treatment of affected mice with doxycycline significantly improved coronary outcome. Inhibiting both the inflammatory response as well as the downstream effects of inflammation were of therapeutic value in this model of KD. These results taken together demonstrate the importance of MMP-9 in the pathogenesis of coronary artery aneurysms in KD. Targeting MMP activity holds the promise of transforming KD from the leading cause of acquired heart disease to a self-limited febrile illness.
Application of Quantitative Structure-activity Relationships to Investigate Xenobiotic Cytotoxicity Mechanisms in Hepatocyte Systems
Keywords: xenobiotic metabolism
hepatotoxicity
QSAR

Hepatotoxicity is a serious adverse health effect caused by drugs and other chemical toxins generally detected in the later stages of drug development or in whole animal studies. Thus, development of screening approaches available for earlier identification of hepatotoxic molecules is necessary. A novel in vitro- in silico test system for the evaluation of the molecular mechanisms of xenobiotic toxicity in primary hepatocyte systems is presented here. It is well established that hepatocytes in vitro are most representative of hepatotoxicity in vivo, and are most useful for the determination of xenobiotic hepatotoxicity mechanisms at the molecular and cellular level. There is an on-going interest in Quantitative Structure-Activity Relationships (QSAR) in toxicology, as it can identify correlations between chemical structure and biological activity. QSAR can be used to evaluate the effects of metabolism and toxicity as many physicochemical descriptors reflect simple molecular properties that can provide insight into the physicochemical nature of the activity under consideration. QSARs were determined for hepatotoxicity of halobenzenes, p-benzoquinones, α,β-unsaturated carbonyl compounds and nitroaromatics towards isolated hepatocytes. A molecular link was established for their proposed toxicity pathways. For example oxidative activation was linked to EHOMO (energy of the highest occupied molecular orbital) values and hydrophobicity (log P) of the chemicals, while reductive activation was linked with ELUMO (energy of the lowest molecular orbital) values and log P. Such relationships may thus be useful for predicting toxicity of other chemicals of the same mechanism of toxicity. Due to the complexity involved in the phenomena of hepatotoxicity, unravelling of structure-hepatotoxicity relationships is a complicated task. A conceptual framework for QSAR modeling is proposed that involves recognition of molecular initiating events as potential endpoints to improve the prediction potential of QSAR models. Acute toxicity of reactive chemicals could be based on an initial reaction with biomolecules, thus the theory of covalent binding reactivity was used to test this concept. Reactivity assays with thiol and amine surrogate nucleophiles were used to determine susceptibility to toxicity. The derived QSAR expressions suggested that covalent binding reactivity is a good correlate to hepatotoxicity, however only if electrophilicity was the main mechanism of toxicity.
The Metaphysics of Agency: Avicenna and his Legacy
Keywords: causality
Avicenna

This dissertation begins with the Islamic philosopher Avicenna, who transforms Aristotle’s conception of the efficient cause in the Metaphysics of his Shifā’. Its first goal is to examine the arguments which constitute Avicenna’s metaphysical account of agency. Its second goal is to examine Scholastic disputes about the causal powers of natural agents that arise in connection with his view. In its final chapter, it relates Medieval debates about efficient causality to Descartes’ account of the causal powers of bodies. One of the original features of Avicenna’s account of agency is his argument for the claim that the existence of contingent things requires an efficient cause. This aspect of his view was influential in the Latin West. Avicenna also holds that the cause of the existence of contingent things is an incorporeal principle, which he describes as an agent who “bestows forms”. I argue that Avicenna fails to resolve the tension between this claim and his commitment to an Aristotelian account of generation. This failure sets the stage for Avicenna’s role in Scholastic disputes about the causal powers of natural agents in cases of generation. Both Aquinas and Suarez attribute to Avicenna the view that generation requires the creation of form. They argue that generation occurs through natural processes. Suarez’s view includes the claim that the substantial form of a substance is an immediate efficient cause of its actions. Suarez defends this claim against other Aristotelians, who hold that a substantial form gives being to a composite substance as a formal cause and that the actions of substances depend directly on their accidents alone. Descartes claims in his letter to Regius of January 1642 that it is absurd to hold that substantial forms are immediate principles of action. He thinks that bodies act in virtue of their modes. Here Descartes sides with those Aristotelians who hold that the actions of substances depend directly on their accidents alone. I argue that this aspect of Descartes’ view tells against Daniel Garber’s claim that his denial of substantial forms deprives bodies of causal efficacy.
Intuition as Evidence in Philosophical Analysis: Taking Connectionism Seriously
Keywords: Connectionism
Intuition
Neural Networks
Connectionist Networks
Concepts
Pragmatism

1. Intuitions are often treated in philosophy as a basic evidential source to confirm/discredit a proposed definition or theory; e.g. intuitions about Gettier cases are taken to deny a justified-true-belief analysis of ‘knowledge’. Recently, Weinberg, Nichols & Stitch (WN&S) provided evidence that epistemic intuitions vary across persons and cultures. In-so-far as philosophy of this type (Standard Philosophical Methodology – SPM) is committed to provide conceptual analyses, the use of intuition is suspect – it does not exhibit the requisite normativity. I provide an analysis of intuition, with an emphasis on its neural – or connectionist – cognitive backbone; the analysis provides insight into its epistemic status and proper role within SPM. Intuition is initially characterized as the recognition of a pattern. 2. The metaphysics of ‘pattern’ is analyzed for the purpose of denying that traditional symbolic computation is capable of differentiating the patterns of interest. 3. The epistemology of ‘recognition’ is analyzed, again, to deny that traditional computation is capable of capturing human acts of recognition. 4. Fodor’s informational semantics, his Language of Thought and his Representational Theory of Mind are analyzed and his arguments denied. Again, the purpose is to deny traditional computational theories of mind. 5. Both intuition and a theory of concepts – pragmatic conceptualism - are developed within the connectionist computational paradigm. Intuition is a particular sort of occurrent signal, and a concept is a counterfactually defined set of signals. Standard connectionist theory is significantly extended to develop my position, and consciousness plays a key functional role. This extension – taking connectionism seriously – is argued to be justified on the basis of the failure of the traditional computing paradigm to account for human cognition. 6. Repercussions for the use of intuition in SPM are developed. Variance in intuition is characterized – and expected - as a kind of bias in the network, either inherent or externally-provoked. The WN&S data is explained in the context of this bias. If SPM remains committed to the use of intuition, then intuition must be taken as a part of a larger body of evidence, and it is from experts – not the folk – that intuitions should be solicited.
Nuclear Factor (Erythroid 2-like) Factor 2 (Nrf2) as Cellular Protector in Bile Acid and Retinoid Toxicities
Keywords: oxidative stress
glutathione
bile acid
Nrf2
retinoic acid
cholestasis
ATP-binding cassette transporters
mitogen activated protein kinase
multidrug resistance associated proteins
adaptive response
antioxidants
thioredoxin reductase
4-hydroxynonenal
lipid peroxidation
glutathione S-transferase
liver toxicity
antioxidant response element
cell defense

Exposure to toxic bile acids (BA) and retinoic acids (RA) is implicated in toxicities related to excessive oxidative stress. This thesis examined roles and mechanisms of the oxidative stress-responsive nuclear factor (erythroid 2-like) factor 2 (Nrf2) in adaptive cell defense against BA and RA toxicities. Using liver cells and mouse models, many antioxidant proteins known to be Nrf2 target genes, particularly the rate-limiting enzyme for glutathione (GSH) biosynthesis, i.e., glutamate-cysteine ligase subunits (GCLM/GCLC), were induced by BA [lithocholic acid (LCA)] or RA (all-trans, 9-cis and 13-cis) treatment. Evidence for increased Nrf2 transactivation by LCA and all-trans-RA was exemplified in HepG2 by: (1) reduced constitutive and inducible expression of GCLM/GCLC upon Nrf2 silencing via small-interfering RNA; (2) increased inducible expression of GCLM/GCLC genes by Nrf2 overexpression, but overexpression of dominant-negative Nrf2 decreased it; (3) increased nuclear accumulation of Nrf2 as signature event of receptor activation; (4) enhanced Nrf2-dependent antioxidant-response-element (ARE) reporter activity as indicative of increased Nrf2 transactivation; and (5) increased Nrf2 occupancy to AREs of GCLM and GCLC. Additionally, in BA-treated HepG2 cells, we observed concomitant increases of many ATP-binding cassette (ABC) transporters (MRPs 1-5, MDR1 and BCRP) in parallel with increased cellular efflux. Nrf2 silencing in HepG2 cells decreased constitutive and inducible expression of MRP2, MRP3 and ABCG2. However, Nrf2-silenced mouse hepatoma cells, Hepa1c1c7, and Nrf2-/- mice had decreased constitutive and/or inducible expression of Mrps 1-4, suggesting species differences in Nrf2-dependent regulation of hepatic ABC transporters. Protection by Nrf2 against BA and RA toxicities was confirmed by observations that Nrf2 silencing increased cell susceptibility to BA- and RA-induced cell death. Moreover, Nrf2-/- mice suffered more severe liver injury than the wildtype. Increased GSH and efflux activity following increased GCLM/GCLC and ABC transporters, respectively, can mitigate LCA toxicity. Activation of MEK1-ERK1/2 MAPK was shown to primarily mediate Nrf2 transactivation and LCA-induced expression of antioxidant proteins and Nrf2-dependent and -independent ABC transporters. In conclusion, Nrf2 activation by BA and RA led to coordinated induction of antioxidant and ABC proteins, thereby counteracting resultant oxidative cytotoxicity. The potential of targeting Nrf2 in management of BA and RA toxicities merits further investigation.
A Randomized Controlled Trial of the Effects of Guided Imagery on Blood Pressure in Hypertensive Pregnant Women
Keywords: Hypertension
Pregnancy
Guided imagery
Relaxation
Anxiety
Randomized controlled trial
Blood pressure

Hypertension occurs in nearly 10% of pregnancies, and is associated with infant and maternal morbidity and mortality. Prior studies of non-pregnant adults have demonstrated the effectiveness of a variety of relaxation therapies in reducing blood pressure. A pilot randomized controlled trial was conducted, the purposes of which were 1) to provide preliminary evidence regarding the usefulness of guided imagery (GI) in reducing blood pressure in hypertensive pregnant women, and 2) to answer feasibility questions for a larger trial. Pregnant women with hypertension prior to 37 weeks gestation (n = 69) were randomized to either 15-minute periods of guided imagery (n = 34), or of quiet rest (QR) (n = 35), twice daily for four weeks or until delivery, whichever came first. Daytime ambulatory mean arterial pressure (MAP), systolic and diastolic blood pressures, anxiety, rest and GI use were measured weekly, to a maximum of four weeks. Sixty women completed at least one week in the study; 46.4% completed four weeks. Compliance was excellent. Intention to treat analysis was used. In the unadjusted analysis, women allocated to GI had significantly lower average daytime ambulatory mean MAP elevations from baseline to their last week of study participation than women allocated to quiet rest (GI: M = 1.58 mmHg, SD = 7.63; QR: M = 5.93 mmHg, SD = 6.55; t = 2.36, p = .02). However, the effect was no longer statistically significant (p = 0.14) when adjusted for baseline mean arterial pressure and gestation. There was no statistically significant difference in the numbers of women who were prescribed antihypertensive medication after randomization (GI: n = 16, QR: n = 13, X2 = 0.74, p = .46). There was also no evidence of an effect of guided imagery on anxiety. Nearly 90% (n = 26) of the guided imagery group indicated they would use it again, either in a subsequent pregnancy or during stressful life events. Given the ease of use, low cost, acceptability to women, and lack of risk of guided imagery, an adequately-powered randomized controlled trial is warranted.