Sustained nitroglycerin (GTN) therapy impairs endothelial function in healthy volunteers and patients with cardiovascular disease, caused by an increase in vascular oxidative stress. This study aims to estimate the effect of rosiglitazone on vascular endothelial function in healthy volunteers continuously dosed to transdermal GTN (0.6mg/hr) for 7 days. To assess endothelial function, forearm blood flow was measured by venous occlusion strain-gauge plethysmography in response to intra-brachial infusions of acetylcholine. GTN-treated subjects experienced significant attenuation of endothelium-dependent responses to acetylcholine (p<0.05; compared to placebo), but was reversed with vitamin C (p=ns; compared to placebo). Endothelium-dependent responses to acetylcholine were blunted in groups randomized to rosiglitazone alone (p<0.05; compared to placebo) and rosiglitazone + GTN (p<0.05 compared to placebo). Interestingly, this effect was not modified by vitamin C. In conclusion, rosiglitazone impairs endothelial function and concurrent therapy with rosiglitazone does not attenuate the adverse effects of transdermal GTN on the vasculature.

Sustained nitroglycerin (GTN) therapy impairs endothelial function in healthy volunteers and patients with cardiovascular disease, caused by an increase in vascular oxidative stress. This study aims to estimate the effect of rosiglitazone on vascular endothelial function in healthy volunteers continuously dosed to transdermal GTN (0.6mg/hr) for 7 days. To assess endothelial function, forearm blood flow was measured by venous occlusion strain-gauge plethysmography in response to intra-brachial infusions of acetylcholine. GTN-treated subjects experienced significant attenuation of endothelium-dependent responses to acetylcholine (p<0.05; compared to placebo), but was reversed with vitamin C (p=ns; compared to placebo). Endothelium-dependent responses to acetylcholine were blunted in groups randomized to rosiglitazone alone (p<0.05; compared to placebo) and rosiglitazone + GTN (p<0.05 compared to placebo). Interestingly, this effect was not modified by vitamin C. In conclusion, rosiglitazone impairs endothelial function and concurrent therapy with rosiglitazone does not attenuate the adverse effects of transdermal GTN on the vasculature.

Background: The rostral ventrolateral medulla (RVLM), location of the sympathetic premotor neurons, plays a pivotal role in central cardiovascular regulation. The peroxisome proliferator-activated receptors-£^ (PPAR£^) agonist is commonly prescribed for the treatment of type II diabetes mellitus by its insulin sensitizing ability. Intriguingly, both animal and human studies revealed that PPAR£^ agonist also possesses blood pressure lowering effect although the underlying mechanism is unknown. We designed a study to evaluate the hypothesis that activation of PPAR£^ in the RVLM mediates the blood pressure lowering effect of PPAR£^ agonist, rosiglitazone. Materials and Methods: The 12-week spontaneously hypertensive rats (SHR) and the age-matched normotensive Wistar Kyoto (WKY) rats were used in this study. Basal systemic arterial pressure (SAP) and heart rate (HR) were measured for one week, followed by oral administration of a synthetic PPAR£^ agonist, rosiglitazone (80 mg/kg/day), or saline for 7 days. The hemodynamic profile was recorded for 4 weeks post treatment. The role of PPAR£^ in the RVLM on blood pressure lowering effect of rosiglitazone was examined by microinjection bilaterally into the RVLM of the PPAR£^ antagonist, GW9662 (5 nmol). In a separated series of experiments, the RVLM of SHR or WKY rats was removed at the end of rosiglitazone or saline treatment. Protein expression of PPAR£\, PPAR£]/£_ or PPAR£^ in the RVLM was analyzed by Western blotting. To ascertain that changes in protein expression are not secondary to perturbation of SAP, expression of PPARs was also examined inSHR that received oral administration of a calcium channel inhibitor, amlodipine (16 mg/kg/day), for 7 days. Results: Compared to saline intake, rosiglitazone significantly lowered the mean SBP (MSBP, 159.2¡Ó9.9 mmHg vs. 139.8¡Ó12.6 mmHg) in SHR, but not WKY rats. This blood pressure lowering effect of rosiglitazone in SHR lasted for at least 10 days post treatment. Rosiglitazone treatment, on the other hand, had no significant effect on HR in SHR or WKY rats. At the end of 7-day treatment, microinjection bilaterally into the RVLM of PPAR£^ antagonist, GW9662 (5 nmol), significantly reversed the blood pressure lowering effect of rosiglitazone in SHR. In addition, protein expression of PPAR£\ or PPAR£^ was significantly upregulated in the RVLM of the SHR but not WKY rats that received rosiglitazone treatment. Oral intake of amlodipine (16 mg/kg/day) for 7 days in SHR significantly lowered MSBP (164.8¡Ó7.7 mmHg to 131.8¡Ó7.8 mmHg), but did not affect protein expression of PPAR£\, PPAR£]/£_ or PPAR£^ in the RVLM of SHR. Conclusion: These results suggest that oral administration of rosiglitazone exerts blood pressure lowering effect via activation of PPARs in the RVLM of SHR. Moreover, upregulation of PPAR£\ or PPAR£^ in the RVLM may underlie the antihypertensive effect of rosiglitazone.

Bladder cancer is currently the 6th most common cancer in the United States, resulting in 17,000 deaths annually. Clinically, bladder cancers are mostly urothelial carcinoma, classified as either non-muscle invasive bladder cancer (NMIBC) or muscle-invasive bladder cancer (MIBC), with the latter having a 5-year survival rate of merely 50%. With recent advances in next-generation sequencing, several international consortia have elucidated molecular subtypes of MIBC. The two major subtypes of MIBCs are basal and luminal; the basal subtype frequently exhibits hallmarks of squamous differentiation and highly expressed basal markers (CD44, KRT14, KRT6A, KRT6B). Tumors of the luminal subtype have papillary morphology and highly express differentiation-associated luminal markers (e.g., KRT20, PPARG, UPKs, and FOXA1). Notably, the transcription factor Peroxisome Proliferator Activated Receptor Gamma (PPARG) gene is frequently amplified in luminal MIBC. And recurrent activating mutations have been reported for its obligatory functional partner Retinoic X Receptor (RXR). In addition, the basal subtype is immune-infiltrated and is postulated as more likely to respond to immunotherapies. In contrast, the luminal subtype is immune-cold. Despite these advances in recent years, the molecular driver of subtype determination, specifically in luminal MIBC, remains poorly understood. Furthermore, subtype-specific targeted therapy for MIBCs is still in its infancy. Our previous work determined that Pparg activation can drive luminal tumor formation. We generated a novel Krt5CreERT2; VP16;Pparg transgenic mouse model, where Pparg expression is constitutively active in basal urothelial cells upon tamoxifen induction. During homeostasis, constitutive Pparg promoted luminal differentiation and cell cycle exit in basal cells but did not produce tumors. However, increased Pparg signaling in activated basal cells following 1-month exposure to bladder-specific carcinogen BBN produced luminal tumors. These tumors are similar both in morphology and molecular markers to human luminal MIBCs. The resulting VP16;Pparg luminal tumors have reduced Nf-kb expression and are immune cold compared to basal tumors. These findings suggest that Pparg is a driver of luminal tumor formation and a suppressor of immune infiltration in bladder cancer. In Chapter 2 of the thesis, I focus on the therapeutic potential of activating Pparg in basal MIBC. We treated mice bearing BBN-induced, Pparg-negative basal tumors with synthetic Pparg ligand - Rosiglitazone (Rosi) and Mek1/2 inhibitor Trametinib (Tram), both of which have been shown to induce Pparg signaling in vitro and in vivo. The combined RosiTram treatment induced apoptosis and significantly reduced tumor burden. The post-treatment urothelium appeared similar in morphology to a healthy urothelium. RosiTram treatment also restored normal urothelial differentiation and generated resident cell types (e.g., superficial cells, intermediate cells, Keratin5+ (K5), basal cells, and Keratin14+ (K14) basal cells) that are normally seen in a healthy urothelium. In contrast, basal tumors are almost entirely composed of K14-Basal cells. Mechanistically, RosiTram treatment partially restores differentiation through retinoic acid signaling and Ezh2 inhibition. Together, our study established targeted transcriptionally and epigenetically reprogramming as a promising differentiation therapeutic approach for basal bladder tumors.

Les thiazolidinediones (TZDs) sont des médicaments antidiabétiques (agonistes des récepteurs nucléaires de type PPAR[gamma]) utilisés au cours des dix dernières années pour le traitement du diabète de type II. Malheureusement leur utilisation peut provoquer, chez certains patients, une rétention accrue de fluides et une formation d?oedèmes rénaux. Des études récentes suggèrent l'implication d'un canal sodique épithélial (ENaC), exprimé au niveau du tubule collecteur rénal, dans ces effets secondaires. En effet, la stimulation des PPAR[gamma] par les TZDs activent les canaux sodiques épithéliaux probablement via l'expression et l'activation de SGK1 (Serum and Glucocorticoid-regulated Kinase 1). Sachant que les transports des ions sodiques et potassiques sont étroitement liés au niveau rénal, notre objectif est de déterminer si les TZDs seraient impliqués dans la régulation des canaux potassiques (ROMK1). Nous montrons qu'en traitant les ovocytes de xénopes exprimant ROMK et PPAR[gamma], avec un TZDs comme la rosiglitazone (RGZ), le courant potassique mesuré par voltage-clamp (TEVC) est augmenté de deux fois. Cette augmentation est bloquée par l'utilisation d'un antagoniste de PPAR[gamma], le GW9662. Nous démontrons aussi l'implication de SGK1 dans la régulation de l'activité des canaux ROMK1 d'une part en mutant son site de phosphorylation sur ROMK1 (sérine 44) et d'autre part en utilisant son inhibiteur, GSK. Finalement les expériences d'immunofluorescences ont montré un recrutement de ROMK1 à la membrane des ovocytes traités à la RGZ. L'ensemble des données présentées dans ce travail suggère que la RGZ augmente le courant potassique en augmentant l'expression de SGK1.

Background: Evidence-based medicine (EBM) receives significant attention worldwide. Many studies have used questionnaires to discuss the factors obstructing the practice of EBM. There has however been no large-scale data analysis on who and when to practice EBM. This study aims to fill this gap in research by applying nationally representative data to analyze EBM practice after the provision of new evidence regarding rosiglitazone prescription. Methods: We used the National Health Insurance Database in Taiwan to analyze the changes in the prescription of rosiglitazone after meta-analysis found the drug to increase the risk of myocardial infarction. The study period was 18 months from the second quarter of 2007 to the fourth quarter in 2008. Two models of doctors¡¦ prescription behaviors were analyzed in the study. We conducted univariate analyses to distinguish significant differences in the variable and applied multivariate logistic analyses to predict the probability of physicians ceasing to prescribe rosiglitazone. Results: We found a significant improvement in EBM practice from specialists and experienced physicians. When compared to other specialists, endocrinologists were four times more likely to change rosiglitazone prescription (OR: 4.129, 95% CI: 2.484-6.863). Doctors with more than 10 years of specialist experience performed better in EBM practice than younger doctors. The hospital level that a physician worked at was not a significant factor. Local urbanization and economic status did not affect the practice of EBM by physicians in clinics either. Conclusions: Our study found that the EBM was still not well practiced among doctors in Taiwan. The practice of new evidence depended on the specialty or professional experience. Younger doctors and doctors working in medical centers seemed not to practice EBM well. In clinics, patients did not have enough influence to modify the doctor¡¦s prescription behavior. There was a significant time lag between the EBM emergence and EBM practice. This suggests that setting up an authoritative organization to provide timely EBM recommendations is very important. Further improvements to the practice of EBM are still urgently needed within the medical community.

No description available.

No description available.

<p>PPAR agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists have been shown to inhibit peripheral eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including decreased cytokine/chemoattractant (IL-5/eotaxin) release, decreased eosinophil migration and/or decreased eosinophil differentiation. This is the first study to show that PPARγ is expressed at the protein level in human airway eosinophils sampled from induced sputum, and confirms PPARγ protein expression in human peripheral blood eosinophils. We demonstrated the novel observation that peripheral blood eosinophil PPARγ protein expression, as measured by flow cytometry, is not different in eosinophils purified from asthmatic subjects compared to healthy controls and these observations suggest that the level of PPARγ expressed in human eosinophils is not related to asthmatic status. Our study also confirms, by real time PCR, the detection of mRNA for PPARγ in airway-derived leukocytes, collected from bronchial washings, increases 24hrs after whole lung allergen challenge. This increase is regulated by Symbicort® and Pulmicort® treatment in most subjects. This is the first study to show increased chemokinesis (random stimulated movement) of eosinophils <em>in vitro</em> at low concentrations of a PPARγ agonist. We have generated data to suggest this is through an effect on calcium signalling. We also observed that higher concentrations of PPAR agonists directly inhibit eotaxin-stimulated eosinophil directional migration. Finally, using methycellulose cultures of non-adherent mononuclear cells and CD34+ progenitor cells, we demonstrate that PPAR activation can inhibit the differentiation of eosinophils <em>in vitro</em>. Collectively, these data demonstrate that PPARγ is expressed consitutively on eosinophils in peripheral blood and airways, and suggest signaling through this receptor with nanomolar concentrations of agonist regulates eosinophilia through inhibition of both eosinophil migration and eosinophil differentiation.</p> / Doctor of Philosophy (PhD)

No / Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily, is activated by several compounds, including the thiazolidinediones. In addition to being a therapeutic target for obesity, hypolipidaemia and diabetes, perturbation of PPARgamma signalling is now believed to be a strategy for treatment of several cancers, including breast. Although differential expression of PPARgamma is observed in tumours compared to normal tissues and PPARgamma agonists have been shown to inhibit tumour cell growth and survival, the interdependence of these observations is unclear. This study demonstrated that the potent, irreversible and selective PPARgamma antagonist GW9662 prevented activation of PPARgamma and inhibited growth of human mammary tumour cell lines. Controversially, GW9662 prevented rosiglitazone-mediated PPARgamma activation, but enhanced rather than reversed rosiglitazone-induced growth inhibition. As such, these data support the existence of PPARgamma-independent pathways and question the central belief that PPARgamma ligands mediate their anticancer effects via activation of PPARgamma.