Jaakko W. Långsjö

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BACKGROUND Anesthetic agents, especially volatile anesthetics and nitrous oxide (N2O), are suspected to perturb cerebral homeostasis and vascular reactivity. The authors quantified the effects of sevoflurane and propofol as sole anesthetics and in combination with N2O on regional cerebral blood flow (rCBF), metabolic rate of oxygen (rCMRO2), and blood(More)
One of the greatest challenges of modern neuroscience is to discover the neural mechanisms of consciousness and to explain how they produce the conscious state. We sought the underlying neural substrate of human consciousness by manipulating the level of consciousness in volunteers with anesthetic agents and visualizing the resultant changes in brain(More)
BACKGROUND Animal experiments have demonstrated neuroprotection by ketamine. However, because of its propensity to increase cerebral blood flow, metabolism, and intracranial pressure, its use in neurosurgery or trauma patients has been questioned. METHODS 15O-labeled water, oxygen, and carbon monoxide were used as positron emission tomography tracers to(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)
Physiological activation increases glucose uptake locally in the brain. However, it is not known how high intensity exercise affects regional and global brain glucose uptake. The effect of exercise intensity and exercise capacity on brain glucose uptake was directly measured using positron emission tomography (PET) and [18F]fluoro-deoxy-glucose ([18F]FDG).(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)
OBJECTIVE To study the effects of S-ketamine on the EEG and to investigate whether spectral entropy of the EEG can be used to assess the depth of hypnosis during S-ketamine anesthesia. METHODS The effects of sub-anesthetic (159 (21); mean (SD) ng/ml) and anesthetic (1,959 (442) ng/ml) serum concentrations of S-ketamine on state entropy (SE), response(More)
[(11)C]Flumazenil is widely used in positron emission tomography (PET) studies to measure GABA(A) receptors in vivo in humans. Although several different methods have been applied for the quantification of [(11)C]flumazenil binding, the reproducibility of these methods has not been previously examined. The reproducibility of a single bolus [(11)C]flumazenil(More)
BACKGROUND The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects. METHODS After mask induction with xenon and intubation, anesthesia was continued with xenon only. BIS, State Entropy and Response Entropy, and electroencephalogram were monitored(More)
BACKGROUND The bispectral index (BIS) and the spectral entropy (state entropy, SE, and response entropy, RE) are depth-of-anaesthesia monitors derived from EEG and have been developed to measure the effects of anaesthetics on the cerebral cortex. We studied whether they can differentiate consciousness from unconsciousness during increasing doses of three(More)