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Fielden M.R.,Roche Holding AG | Fielden M.R.,Amgen | Hassani M.,Roche Holding AG | Hassani M.,Roger Williams Medical Center | And 9 more authors.
Experimental and Toxicologic Pathology | Year: 2010

A number of drugs and drug candidates, including fenfluramine and ergot derivatives, are associated with valvulopathy in humans; however, these responses are poorly predicted from animal studies. In vitro and in vivo evidence suggests that these compounds exert their pathological effect through activation of serotonin 2B receptor (5HT2BR) signaling. However, the variable effect of fenfluramine and other 5HT2BR agonists in rodents has cast doubt on the relevance of animal findings to predicting human risk. Herein, a candidate compound, RO3013, induced subendocardial cell proliferation in the mitral and tricuspid valves in rats after only 3 days of daily dosing. Additionally, there was a treatment-related increase in immunostaining of the proliferation marker Ki67, and phosphorylated Smad3 in the heart indicative of TGFΒ signaling co-localized with 5HT2BR expression. To substantiate the hypothesis that RO3013-induced valvular proliferation is secondary to 5HT2BR activation, the compound was evaluated in vitro and found to bind to the human 5HT2BR with a Ki of 3.8γM; however, it was virtually devoid of agonist activity in a functional assay in human cells. By contrast, RO3013 bound to the rat 5HT2BR with a Ki of 1.2γM and activated the receptor with an EC50 of 0.5γM. This agonist potency estimate is in good agreement with the free plasma concentrations of RO3013 at which valvular proliferation was observed. These results suggest that the rat may be susceptible to 5HT2BR-mediated valvular proliferation similar to humans; yet, the significant differences between binding and functional activities can be a possible explanation for the observed species-selective receptor responses. © 2009 Elsevier GmbH. Source


Shin Y.S.,National Jewish Health | Takeda K.,National Jewish Health | Ohnishi H.,National Jewish Health | Jia Y.,National Jewish Health | And 8 more authors.
Annals of Allergy, Asthma and Immunology | Year: 2011

Background: Asthma is a chronic airway inflammatory disease that is associated with a large influx of inflammatory cells. Several chemokines and chemokine receptors play critical roles in the development of allergic airway inflammation. Objective: Because polarized human TH2 cells express a functional CXCR3 chemokine receptor, we evaluated the effects of a selective CXCR3 inhibitor in a mouse model of allergic airway disease. Methods: Ovalbumin-specific CD8+ T effector cells were generated from OT-1 mice in the presence of interleukin 2. The activity of a CXCR3 inhibitor was examined in vitro by monitoring Ca2+ influx after receptor ligation. In vivo, the activity was assessed in sensitized and challenged mice by monitoring airway function, inflammatory parameters, including cellular infiltrates and cytokines in the bronchoalveolar lavage fluid. Results: Approximately 40% of CD8+ T effector cells expressed the CXCR3 receptor. In vitro, CXCR3 antagonism reduced Ca2+ influx after receptor engagement. In contrast, the CXCR3 antagonist had little to no effect on airway function or inflammatory parameters despite adequate exposure levels. Conclusions: CXCR3 antagonism did not prevent allergen-induced airway hyperresponsiveness or airway inflammation in a mouse allergy model despite having activity in in vitro functional assays. © 2011 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved. Source


Manfra D.J.,Schering | Engstrom L.W.,Schering | Bober L.,Schering | Chen S.-C.,Schering | And 12 more authors.
PPAR Research | Year: 2010

The kinetics of metabolic and inflammatory parameters associated with obesity were evaluated in a murine diet-induced obesity (DIO) model using a diet high in fat and cholesterol. Cellular infiltration and mediator production were assessed and shown to be therapeutically modulated by the PPARgamma agonist rosiglitazone. C57BL/6 mice were maintained on a 45 fat/0.12% cholesterol (HF/CH) or Chow diet for 3, 6, 16, or 27 weeks. Flow cytometry was employed to monitor peripheral blood monocytes and adipose tissue macrophages (ATM). Gene expression and protein analysis methods were used to evaluate mediator production from total epididymal fat (EF), stromal vascular fraction (SVF), and sorted SVF cells. To investigate therapeutic intervention, mice were fed a HF/CH diet for 12 weeks and then a diet formulated with rosiglitazone (5mg/kg) for an additional 6 weeks. A HF/CH diet correlated with obesity and a dramatic proinflammatory state. Therapeutic intervention with rosiglitazone attenuated the HF/CH induced inflammation. In addition, a novel population was found that expressed the highest levels of the pro-inflammatory mediators CCL2 and IL-6. © 2010 Laura W. Engstrom et al. Source


Lakshman K.M.,Boston University | Kaplan B.,Lahey Clinic Medical Center | Travison T.G.,Boston University | Basaria S.,Boston University | And 5 more authors.
Journal of Clinical Endocrinology and Metabolism | Year: 2010

Background: During testosterone (T) therapy, T is partly converted to 17β-estradiol (E 2) and 5α-dihydrotestosterone (DHT). Effects of age, testosterone dose, and body composition on total and free E 2 and DHT levels are unknown. Objective: We evaluated age and dose-related differences in E 2 and DHT levels in response to graded doses of testosterone enanthate in young and older men. Methods: Fifty-one young (aged 19-35 yr) and 52 older (aged 59-75 yr) men completed treatment with monthly injections of a GnRH agonist plus randomly assigned weekly doses of testosterone enanthate (25, 50, 125, 300, or 600 mg) for 5 months. Results: During testosterone administration, total and free E 2 levels increased dose-dependently (dose effect, P<0.001) in both young and older men. Total and free E 2 levels and E 2:T ratios during T administration were higher in older than young men, but age-related differences in free E 2 and free E 2:T ratioswerenot significant after adjusting for testosterone levels, percentage fat mass,and SHBG. DHT levels and DHT:T ratios were dose-related but did not differ between young and older men. Mechanistic modeling of free hormone data revealed that the conversions of T to E 2 and DHT were both consistent with saturable Michaelis-Menten kinetics. The in vivo K m values were estimated to be 1.83 nM for aromatase and 3.35 nM for 5α-reductase, independent of age. The V max parameter for E 2 was 40% higher in older men than younger men, but V max for DHT was not significantly different between age groups. Conclusions: During imtestosterone administration, E 2 and DHT levels exhibit saturable increases with dose. The rate of whole body aromatization is higher in older men, partly related to their higher percentage fat mass, SHBG, and testosterone levels. Copyright © 2010 by The Endocrine Society. Source


Amit O.,Glaxosmithkline | Mannino F.,Glaxosmithkline | Stone A.M.,Astrazeneca | Bushnell W.,Glaxosmithkline | And 3 more authors.
European Journal of Cancer | Year: 2011

Purpose: Progression free survival (PFS) is increasingly used as a primary end-point in oncology clinical trials. This paper provides observations and recommendations on the use of a blinded independent central review (BICR) for progression. Patients and methods: The findings and recommendations are based on extensive simulations and a meta-analysis based on 27 previously conducted randomised phase III trials with BICR performed by the Pharmaceutical Research and Manufacturers Association (PhRMA) sponsored PFS Independent Review Working Group. Results: Results of the meta-analysis demonstrate a strong correlation between LE and BICR estimates of treatment effect (R = 0.947). Further, differences between treatment groups in discordance rates predict the differences between LE and BICR estimates of treatment effect supporting the use of a sample-based BICR on a subgroup of patients. Conclusion: The meta-analysis demonstrates that local evaluation (LE) provides a reliable estimate of the treatment effect with little evidence for systematic evaluation bias. Therefore, when a trial is blinded or a large effect on PFS is observed a BICR may not be warranted. When a BICR is warranted, a sample-based BICR may provide a reduction in operational complexity without compromising the credibility of trial results. While for large trials that are not adequately blinded a sample-based BICR may be recommended. A full BICR should be considered in the case of smaller trials or in situations in which there is a particular need to increase the confidence in the LE results. © 2011 Elsevier Ltd. All rights reserved. Source

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