Brett T. Marck

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PURPOSE Abiraterone is a potent inhibitor of the steroidogenic enzyme CYP17A1 and suppresses tumor growth in patients with castration-resistant prostate cancer (CRPC). The effectiveness of abiraterone in reducing tumor androgens is not known, nor have mechanisms contributing to abiraterone resistance been established. EXPERIMENTAL DESIGN We treated human(More)
Mice with a targeted disruption of the dopamine beta-hydroxylase (DBH) gene are unable to synthesize norepinephrine (NE) and epinephrine. These mice have elevated levels of dopamine in most tissues, although the levels are only a fraction of those normally found for NE. It is noteworthy that NE can be restored to normal levels in many tissues after a single(More)
Relapse of castration-resistant prostate cancer (CRPC) that occurs after androgen deprivation therapy of primary prostate cancer can be mediated by reactivation of the androgen receptor (AR). One important mechanism mediating this AR reactivation is intratumoral conversion of the weak adrenal androgens DHEA and androstenedione into the AR ligands(More)
Hypoxia-inducible factor (HIF) transcription factors respond to multiple environmental stressors, including hypoxia and hypoglycemia. We report that mice lacking the HIF family member HIF-2alpha (encoded by Epas1) have a syndrome of multiple-organ pathology, biochemical abnormalities and altered gene expression patterns. Histological and ultrastructural(More)
Mice that cannot make dopamine (DA), a condition caused by the selective inactivation of tyrosine hydroxylase in dopaminergic neurons, are born normal but gradually become hypoactive and hypophagic, and die at 3 weeks of age. We characterized the feeding and locomotor responses of these DA-deficient (DA-/-) mice to 3, 4-dihyroxy-L-phenylalanine (L-DOPA) to(More)
Dopamine-deficient (DD) mice cannot synthesize dopamine (DA) in dopaminergic neurons due to selective inactivation of the tyrosine hydroxylase gene in those neurons. These mice become hypoactive and hypophagic and die of starvation by 4 weeks of age. We used gene therapy to ascertain where DA replacement in the brain restores feeding and other behaviors in(More)
Multiple endocrine neoplasia type 2B (MEN2B) is an autosomal dominant syndrome characterized by the development of medullary thyroid carcinoma, pheochromocytomas, musculoskeletal anomalies and mucosal ganglioneuromas. MEN2B is caused by a specific mutation (Met918-->Thr) in the RET receptor tyrosine kinase. Different mutations of RET lead to other(More)
CONTEXT Concern exists that androgen treatment might adversely impact prostate health in older men. Dihydrotestosterone (DHT), derived from local conversion of testosterone to DHT by 5α-reductase enzymes, is the principal androgen within the prostate. Exogenous androgens raise serum DHT concentrations, but their effects on the prostate are not clear. (More)
Aging mammals lose the ability to maintain energy balance, exhibiting decreased appetite (anorexia) and impaired ability to maintain body weight. To determine the contribution of hypothalamic neuropeptides, two experiments were performed in male Brown Norway rats. To assess the hypothalamic neuropeptide response to food deprivation, young (Y; 4 mo old),(More)
OBJECTIVE Ischaemic stroke is a major cause of morbidity and mortality in elderly men. Our main objective was to examine whether testosterone (T) or dihydrotestosterone (DHT) was associated with incident ischaemic stroke in elderly men. DESIGN Cohort study. PARTICIPANTS Elderly men in the Cardiovascular Health Study who had no history of stroke, heart(More)