Tapio Viljanen

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Aims/hypothesis. The aim of the Diabetes Prevention Study is to assess the efficacy of an intensive diet-exercise programme in preventing or delaying Type II (non-insulin-dependent) diabetes mellitus in subjects with impaired glucose tolerance, to evaluate the effects of the intervention programme on cardiovascular risk factors and to assess the(More)
BACKGROUND Animal studies have demonstrated neuroprotective properties of S-ketamine, but its effects on cerebral blood flow (CBF), metabolic rate of oxygen (CMRO2), and glucose metabolic rate (GMR) have not been comprehensively studied in humans. METHODS Positron emission tomography was used to quantify CBF and CMRO2 in eight healthy male volunteers(More)
We investigated the metabolism of human brown adipose tissue (BAT) in healthy subjects by determining its cold-induced and insulin-stimulated glucose uptake and blood flow (perfusion) using positron emission tomography (PET) combined with computed tomography (CT). Second, we assessed gene expression in human BAT and white adipose tissue (WAT). Glucose(More)
PURPOSE The outcome of locally advanced head-and-neck cancer often is poor. An important determinant of treatment failure is tumor hypoxia arising from an inappropriate blood supply. Quantitation of the hypoxic fraction and blood flow in vivo may provide prognostic information and a means to target specifically tumor cells resistant to conventional(More)
BACKGROUND & AIMS The liver is inaccessible to organ balance measurements in humans. To validate [(18)F]fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) in the quantification of hepatic glucose uptake (HGU), we determined [(18)F]FDG modeling parameters, lumped constant (LC), and input functions (single arterial versus dual). METHODS(More)
Rosiglitazone, a thiazolidinedione, enhances peripheral insulin sensitivity in patients with type 2 diabetes. Because the synergic action of insulin and exercise has been shown to be decreased in insulin resistance, the aim of this study was to compare the effects of rosiglitazone and metformin on muscle insulin responsiveness at rest and during exercise in(More)
BACKGROUND The authors have recently shown with positron emission tomography that subanesthetic doses of racemic ketamine increase cerebral blood flow but do not affect oxygen consumption significantly. In this study, the authors wanted to assess the effects of racemic ketamine on regional glucose metabolic rate (rGMR) in similar conditions to establish(More)
To elucidate the role of adipose tissue glucose uptake in whole-body metabolism, sc and visceral adipose tissue glucose uptake and perfusion were measured in 10 nonobese and 10 age-matched obese men with positron emission tomography using [(18)F]-2-fluoro-2-deoxy-D-glucose, and [(15)O]-labeled water during normoglycemic hyperinsulinemia. Whole-body and(More)
The purpose of this study was to investigate the effects of exercise on myocardial glucose uptake and whether the pattern of glucose uptake is the same as in skeletal muscle. Glucose uptake was measured using positron emission tomography (PET) and 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG). Twelve healthy men were studied during rest, while 14 subjects were(More)
OBJECTIVE Inactive brown adipose tissue (BAT) may predispose to weight gain. This study was designed to measure metabolism in the BAT of obese humans, and to compare it to that in lean subjects. The impact of weight loss on BAT and the association of detectable BAT with various metabolic characteristics were also assessed. DESIGN AND METHODS Using(More)