J Andersson

Uppsala University Hospital, Uppsala, Uppsala, Sweden

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Publications (28)61.29 Total impact

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    ABSTRACT: Background: Due to a few reports of cerebral dysfunction in connection with isoflurane-induced hypotension and concomitant hypocapnia, positron emission tomography (PET) was used to measure cerebral oxygenation and blood flow during similar conditions with isoflurane or propofol.Methods: The short-lived radionuclide 15O was used for measurement of cerebralmetabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and oxygen extraction ratio (OER) regionally in rhesus monkeys during normotensive/normocapnic and hypotensive/hypocapnic conditions, mean arterial pressure 100–110 and 50–65 mmHg and PaCO2 4.4–5.4 and 3.4-4.4 kPa, respectively. Isoflurane or propofol anaesthesia was given (n=4 in both groups), supported with 70% nitrous oxide and preceded by ketamine anaesthesia (baseline).Results: PET revealed wide variations in CBF between regions during isoflurane anaesthesia, particularly in comparison with propofol anaesthesia, while rCMRO2 decreased globally in a dose-dependent manner during both isoflurane and propofol anaesthesia. The metabolism-flow coupling was intact during propofol but not during isoflurane anaesthesia. Hypotension reduced rCBF, and rOER increased globally with both study drugs when changing from normo- to hypotension. However, this rOER increase was not significant when using PaCO2 as a co-variate, and rOER was never above an arbitrary limit for hypoxia of 70%. Thus, hypocapnia, rather than hypotension, was responsible for the somewhat higher rOER measured.Conclusion: PET indicated adequate cerebral oxygenation during isoflurane and propofol anaesthesia, despite disparate blood-flow patterns. Hypotension and concomitant moderate hyperventilation reduced rCBF, but did not result in hypoxia.
    Acta Anaesthesiologica Scandinavica 12/2008; 41(8):1002 - 1010. · 2.36 Impact Factor
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    ABSTRACT: In a previous investigation concerning the hemodynamic and metabolic changes over time displayed by sequential positron emission tomography (PET) in a middle cerebral artery (MCA) occlusion/reperfusion primate model, a metabolic threshold for irreversible ischemia could be identified (reduction of metabolic rate of oxygen [CMRO(2)] to approximately 60% of the contralateral hemisphere). To evaluate the potential of microdialysis (MD) as an instrument for chemical brain monitoring, the aim of this subsequent study was to relate the chemical changes in MD levels directly to the regional metabolic status (CMRO(2) above or below the metabolic threshold) and the occurrence of reperfusion, as assessed by PET. Continuous MD (2 probes in each brain) and sequential PET measurements were performed during MCA occlusion (2 hours) and 18 hours (mean) of reperfusion in 8 monkeys (Macaca mulatta). Energy-related metabolites (lactate, pyruvate, and hypoxanthine) and glutamate were analyzed. The MD probe regions were divided into 3 categories on the basis of whether CMRO(2) was below or above 60% of the contralateral region (metabolic threshold level) during MCA occlusion and whether reperfusion was obtained: severe ischemia with reperfusion (n=4), severe ischemia without reperfusion (n=4), and penumbra with reperfusion (n=5). The lactate/pyruvate ratio, hypoxanthine, and glutamate showed similar patterns. MD probe regions with severe ischemia and reperfusion and probe regions with severe ischemia and no reperfusion displayed high and broad peaks, respectively, during MCA occlusion, and the levels almost never decreased to baseline. Penumbra MD probe regions displayed only slight transient increases during MCA occlusion and returned to baseline. This experimental study of focal ischemia showed that the extracellular changes of energy-related metabolites and glutamate differed depending on the ischemic state of the brain during MCA occlusion and depending on whether reperfusion occurred. If MD proves to be beneficial in clinical practice, it appears important to observe relative changes over time.
    Stroke 08/2001; 32(7):1574-80. · 6.16 Impact Factor
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    ABSTRACT: The effect of long-term treatment with tacrine (tetrahydroaminoacridine) was studied in three Alzheimer patients (aged 57, 64, and 68 years) with mild dementia. All three patients had a Mini-Mental State Examination score of 24/30 and carried at least one apolipoprotein E (ApoE) [varepsilon]4 allele. Tacrine was given in doses between 80 and to 160 mg daily for 13-31 months. A lower tacrine concentration was observed generally in cerebrospinal fluid (CSF) compared with plasma. The acetylcholinesterase activity in CSF tended to be increased following longer periods of tacrine treatment, whereas the butyrylcholinesterase activity was decreased. The three patients repeatedly underwent positron emission tomography investigation of cerebral blood flow, nicotinic receptors, cerebral glucose metabolism, and electroencephalogram (EEG) and cognitive tests. Positive influences on these parameters were observed following both short-term and long-term treatment with tacrine. Improvement of nicotinic receptors (measured as 11C-nicotine binding), cerebral blood flow, EEG. and some cognitive tests (trail making test, block design test) occurred earlier after initiation of tacrine treatment compared with the glucose metabolism, which was increased after several months of tacrine treatment. An improvement in attention (trail making test) was observed following tacrine as sign for frontal lobe activation (EEG). The functional effects of tacrine in Alzheimer patients appeared to be related to both dose and length of cholinesterase inhibitor treatment. (C) 1998 Lippincott Williams & Wilkins, Inc.
    Alzheimer Disease and Associated Disorders 08/1998; 12(3). · 2.73 Impact Factor
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    ABSTRACT: To reveal areas in the central nervous system of importance for electrodermal control, regional cerebral blood flow (rCBF) was correlated to nonspecific skin conductance fluctuations (NSF) during aversive and nonaversive conditions. Participants viewed a TV screen displaying white noise or snake videotapes presented both with and without electric shocks given to the right hand. H2 15 O positron emission tomography was used to measure rCBF, and the constant voltage technique was used to measure NSF from the left hand. Electrodermal activity was positively related to rCBF in the left primary motor cortex (MI, Brodmann's Area 4) and bilaterally in the anterior (Areas 24 and 32) and posterior cingulate cortex (Area 23). Negative relations were observed bilaterally in the secondary visual cortex (Areas 18 and 19) and the right inferior parietal cortex (Area 39), with a tendency also for the right insular cortex (Areas 13, 15, and 16). Because results from lesion and stimulation studies in humans converge with the present imaging results, we conclude that the cingulum and the motor cortex, in addition to the parietal and possibly the insular cortex, form part of one or several distributed neural network(s) involved in electrodermal control. Because these areas also support anticipation, affect, and locomotion, electrodermal responses seem to reflect cognitively or emotionally mediated motor preparation.
    Psychophysiology 03/1998; 35(2):179-85. · 3.26 Impact Factor
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    ABSTRACT: The main objective of neurointensive care is to counteract the development of secondary brain ischemia. The management is focused on preventing, detecting and correcting secondary insults that are likely to produce ischemic brain damage. This requires intensive multimodality monitoring of the brain. There is no reliable technique available for continuous monitoring of cerebral blood flow and therefore intermittent methods have to be used in some cases for objective measurement of cerebral perfusion. PET allows measurements of both cerebral blood flow and metabolism, which is essential for the assessment of the energy metabolic state of the brain tissue. PET may be used to guide therapeutic intervention, to evaluate the effect of treatment, to validate new techniques for monitoring of the brain and to determine the efficacy of potential neuroprotective drugs. The possibilities that PET offers in neurointensive care and research are illustrated. The experiences from the application of PET in the evaluation of pharmacological treatment of increased intracranial pressure in head injured patients and the use of PET in combination with intracerebral microdialys, in an MCA-occlusion-reperfusion primate model and in patients with subarachnoid hemorrhage, to validate intracerebral microdialysis as an instrument for chemical monitoring of the brain during neurointensive care, are reported.
    Nordisk medicin 02/1998; 113(2):49-52.
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    ABSTRACT: Due to a few reports of cerebral dysfunction in connection with isoflurane-induced hypotension and concomitant hypocapnia, positron emission tomography (PET) was used to measure cerebral oxygenation and blood flow during similar conditions with isoflurane or propofol. The short-lived radionuclide 15O was used for measurement of cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and oxygen extraction ratio (OER) regionally in rhesus monkeys during normotensive/normocapnic and hypotensive/hypocapnic conditions, mean arterial pressure 100-110 and 50-65 mmHg and PaCO2 4.4-5.4 and 3.4-4.4 kPa, respectively. Isoflurane or propofol anaesthesia was given (n = 4 in both groups), supported with 70% nitrous oxide and preceded by ketamine anaesthesia (baseline). PET revealed wide variations in CBF between regions during isoflurane anaesthesia, particularly in comparison with propofol anaesthesia, while rCMRO2 decreased globally in a dose-dependent manner during both isoflurane and propofol anaesthesia. The metabolism-flow coupling was intact during propofol but not during isoflurane anaesthesia. Hypotension reduced rCBF, and rOER increased globally with both study drugs when changing from normo- to hypotension. However, this rOER increase was not significant when using PaCO2 as a covariate, and rOER was never above an arbitrary limit for hypoxia of 70%. Thus, hypocapnia, rather than hypotension, was responsible for the somewhat higher rOER measured. PET indicated adequate cerebral oxygenation during isoflurane and propofol anaesthesia, despite disparate blood-flow patterns. Hypotension and concomitant moderate hyperventilation reduced rCBF, but did not result in hypoxia.
    Acta Anaesthesiologica Scandinavica 10/1997; 41(8):1002-10. · 2.36 Impact Factor
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    ABSTRACT: The effects of eltanolone anaesthesia in humans on regional cerebral blood flow, regional cerebral metabolic rate of oxygen and oxygen extraction ratio were to be evaluated using positron emission tomography (PET). Six healthy male volunteers were studied. Series of PET-measurements with 15O and H2(15)O were carried out in the awake state (baseline)(n = 6), during eltanolone anaesthesia (n = 5) and during early recovery (n = 5), when the subjects were oriented with respect to person, place and time. Eltanolone was given as a programmed infusion. Cerebral blood flow (rCBF) was reduced in almost all cortex regions studied by 31 +/- 16% (mean +/- SD, P < 0.01). During recovery rCBF increased to 109 +/- 26% of pre-anaesthetic baseline levels (P < 0.01). Eltanolone in the doses administered lowered oxygen metabolism (rCMRO2) by 52 +/- 8% (P < 0.01) in cortex regions. During recovery rCMRO2 increased to 90 +/- 13% of baseline (P < 0.01). The oxygen extraction (OER) in cortical regions decreased by 32 +/- 23% (P < 0.01) during anaesthesia and returned to 82 +/- 10% of baseline (P < 0.01) during recovery. Less reduction in cortical blood flow during eltanolone anaesthesia was seen in the uncus (P < 0.01), though no differences in the depression of oxygen metabolism were seen. Oxygen extraction remained homogeneous throughout the brain. Eltanolone anaesthesia was shown to reduce cerebral oxygen metabolism and cerebral blood flow in healthy volunteers. There were no signs of ischaemic effects.
    Acta Anaesthesiologica Scandinavica 10/1997; 41(9):1204-12. · 2.36 Impact Factor
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    ABSTRACT: In order to examine the relationship between reduced visual acuity in human strabismic amblyopia and the cortical activation pattern, we studied, by use of positron emission tomography (PET) and the H2(15)O bolus technique, changes in the regional cerebral blood flow (rCBF) induced by monocular visual stimulation of 8 individuals with this disorder. Individual amblyopic thresholds for monocular detection of the checkerboard pattern were employed as stimuli for both eyes during PET scans. Statistical analysis of subtracted images showed significant increases in rCBF (P < 0.05) by the stimulation of the sound eye localized bilaterally to Brodmann's areas (BAs) 17-19. The cortical response evoked by the amblyopic eye was significantly reduced (P < 0.05) in the ipsilateral BAs 18, 19. These results suggest that the reduction in contrast sensitivity (pattern vision) in amblyopia is coupled with deactivation in identifiable regions of occipital visual areas, including ipsilateral BAs 18,19.
    Neuroscience Letters 05/1997; 225(3):173-6. · 2.03 Impact Factor
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    ABSTRACT: Despite extensive research, the mechanisms for the effects of organic solvents on the central nervous system are still unknown. One mechanism proposed is that solvents interfere with the synthesis of neurotransmitters. In the present study 11 male healthy volunteers were exposed during 15 min to 100 p.p.m. toluene at light physical exercise, and the dopamine decarboxylase activity and number of terminals in putamen were measured before and after exposure by positron emission tomography. Two different tracers were used [beta-11C]L-DOPA for decarboxylase activity during the in vivo synthesis of dopamine, and [11C]nomifensine to estimate the number of terminals. Although there was a slight increase in the rate of dopamine synthesis in the putamen after the exposure, this difference was not statistically significant (P = 0.4). No effect was observed with regard to the uptake of nomifensine. There was no significant relationship between the dose of toluene and rate of dopamine synthesis, and no significant correlation between the time from end of exposure to start of the PET-camera and DOPA. Our findings indicate that short term exposure to 100 p.p.m. of toluene does not affect the rate of dopamine synthesis or the number of presynaptic terminals.
    Human &amp Experimental Toxicology 04/1997; 16(3):171-6. · 1.45 Impact Factor
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    ABSTRACT: The objective of this study was to test the hypothesis that long-term occupational exposure to organic solvents may effect the levels and turnover of dopamine in man. A study was performed on 17 patients with neuropsychiatric symptoms due to occupational solvent exposure, and 11 healthy non-exposed male volunteers (controls). Positron emission tomography (PET) was used to assess striatal dopaminergic function, using L-[11C]DOPA, [11C]nomifensine and [11C]raclopride as tracers. The rate of dopamine synthesis was significantly increased among subjects with occupational exposure to organic solvents compared with non-exposed controls. After controlling for the difference in age between exposed and controls, the effect of solvent exposure became less apparent and was reduced from +32% (P = 0.009) to +25% (P = 0.07). There were no differences with regard to the binding of [11C]nomifensine. Patients with and without the diagnosis of toxic encephalopathy did not differ with regard to their putaminal uptake of L-[11C]DOPA, [11C]nomifensine and [11C]raclopride. The data support the hypothesis that long-term exposure to organic solvents may increase the rate of dopamine synthesis in the brain without affecting the number of presynaptic terminals or postsynaptic dopamine receptors.
    International Archives of Occupational and Environmental Health 02/1997; 70(3):180-6. · 2.10 Impact Factor
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    ABSTRACT: Positron emission tomography was used to study regional cerebral blood flow (H215O method) in groups of young and older adults during implicit and explicit retrieval, following a procedure devised by Squire et al. (1992). At study, subjects were exposed to four lists of words. Following list presentation, subjects were presented with three-letter word stems under four conditions: (1) silent viewing, (2) completion of word stems that could not form words from the study list, with the instruction to provide the first word that came to mind (baseline), (3) completion of word stems, half of which could form words from the study list, with the instruction to provide the first word that came to mind (priming), and (4) completion of word stems, half of which could form words from the study list, with the instruction to use the stems as cues for recall of list words (memory). The behavioral data indicated an agerelated deficit in cued recall that was reduced in priming. Both age groups showed a similar decrease of blood flow in right posterior cortex during priming relative to baseline. During cued recall, bilateral increases of blood flow were observed in prefrontal cortex and anterior cingulate gyrus for both age groups. The young adults showed selective increases of activity in left cerebellum and Wernicke's area, whereas the older adults showed a selective bilateral activation in the perirhinal region of the medial-temporal cortex during cued recall. The results suggest a simiiar biological basis of priming in both age groups: a decrease in the neural activity required to process a particular stimulus during a subsequent encounter compared with a previous one. In addition, the importance of prefrontal regions for conscious retrieval was substantiated and extended to late adulthood. Finally, the agedifferential activations observed during cued recall were discussed relative to prominent concepts in the current literature on cognitive aging (e.g., speed of processing, self-initiated operations, cross-modal recoding).
    Journal of Cognitive Neuroscience 01/1997; 9(3):378-391. · 4.49 Impact Factor
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    ABSTRACT: Functional imaging techniques offer new possibilities for further understanding of changes in functional correlates of structural and biological changes in dementia disorders like Alzheimer's disease (AD). Regional disturbances in glucose metabolism and cerebral blood flow are known to occur in AD brains and probably roughly correlate to changes in neurotransmitter activities. A proper estimate would be to visualize the neuroreceptors themselves. In this study the cholinergic nicotinic and muscarinic receptors were studied in brain by positron emission tomography (PET). The rate constant k2* (s) (-)11C-nicotine was significantly higher (+43%) in temporal cortex of AD patients compared to controls (p < 0.017) indicating a lower binding of 11C-nicotine in AD brains compared to controls. Treatment with the cholinesterase inhibitor tacrine (80 mg daily) during 3 months to AD patients resulted in a mean plasma concentration of 7.7 +/- 0.8 ng/ml and a corresponding inhibition of the cholinesterase activity in plasma by 34 +/- 5%. A significantly lower k2* (increased binding) for 11C-nicotine binding (-15%; p < 0.006) was obtained in the temporal cortex after 3 months of treatment compared to prior treatment. The muscarinic antagonist 11C-benztropine was used to visualize muscarinic receptors and the binding capacity of 11C-benztropine (KR) was found to be decreased in the temporal cortex after 3 months of tacrine treatment.
    Dementia and Geriatric Cognitive Disorders 01/1997; 8(2):78-84. · 2.79 Impact Factor
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    ABSTRACT: Intracerebral microdialysis (MD) was applied in patients with subarachnoid hemorrhage. The regional CBF, the CMRO2, and oxygen extraction ratio (OER) were measured with simultaneous positron emission tomography (PET). The aim was to directly correlate alterations in dialysate levels of energy-related metabolites (lactate, lactate/pyruvate ratio, hypoxanthine) and excitatory amino acids (EAAs) (glutamate and aspartate) to the energy state in the MD probe region as determined by PET. Regional ischemia was defined according to Heiss et al. and Lassen (Heiss et al., 1992; Lassen, 1966). Whole-brain ischemia was considered present when the OER for the whole brain exceeded the mean whole-brain OER + 2 SD of six reference patients. In general, the presence of whole-brain ischemia and/or regional ischemia within the region of the MD probe was associated with increased levels of energy-related metabolites and EAAs retrieved by MD. Increased levels of energy-related metabolites and EAAs were only occasionally seen when PET did not show any signs of ischemia or when signs of regional ischemia were found remote from the MD probe region. Thus, the energy-related metabolites and EAAs may be used as extracellular “markers” of ischemia. PET may be of use in defining critical ischemic regions (tissue at risk) where the MD probe can be inserted for chemical monitoring.Keywords: Cerebral blood flow; Cerebral metabolism; Ischemia; Micro-dialysis; Positron emission tomography; Subarachnoid hemorrhage
    Journal of Cerebral Blood Flow & Metabolism 06/1996; 16(4):637-644. · 5.40 Impact Factor
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    ABSTRACT: To elucidate cerebral regions involved in adaptation to mirror drawing, changes in regional cerebral blood flow were measured using positron emission tomography at different levels of adaptation. A significant signal in subtraction images was localized in left Brodmann's area 45 (ventral sub-region of Broca's area) in the initial phase of the mirror drawing. This activity decreased as adaptation proceeded, and a small cluster in area 19 of the medial extrastriate cortex became significantly active. An after-effect of ca. 30 min of mirror-drawing was also detected in the right area 21 of the temporal association cortex. The results first demonstrated visuo-cortical regions where neurons might change their activity to evoke plastic response to the inverted vision.
    Neuroscience Letters 06/1996; 209(3):185-8. · 2.03 Impact Factor
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    ABSTRACT: Evaluation of positron emission tomography (PET) using (18)fl 18F-2-fluoro-2-deoxy-D-glucose (18FDG) and L-methyl-11C-methionine in the diagnosis and staging of urinary bladder carcinoma. Twenty-three patients with biopsy-proven urinary bladder carcinoma were examined with PET after intravenous injection of 11C-methionine; 2 were also examined with 18FDG. The results from the PET investigations were compared with CT or MR findings and TNM classification before and after treatment. The urinary excretion of 18FDG prevented distinction of the primary tumour from the surrounding tracer. With 11C-methionine it was possible to detect 18/23 primary tumours. A trend was seen, suggesting that the higher the uptake values of 11C-methionine in the tumour, the greater the tumour stage. It is possible to visualize urinary bladder tumours larger than 1 cm in diameter with PET using (11)C-methionine, but the value of the method in the staging of the lesions is not superior to conventional methods.
    Acta Radiologica 04/1996; 37(2):180-5. · 1.33 Impact Factor
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    ABSTRACT: Treatment of tumours and vascular lesions in or close to eloquent cortex may inflict neurological deficits. Intra-operative mapping procedures have been used for many decades in efforts to minimize neurological sequelae. The possibility for non-invasive pre-operative brain mapping has emerged with the advent of positron emission tomography (PET). In this paper we report on 11 patients with a tumour or vascular lesion in or close to the sensorimotor (10 patients) or visual cortex (one patient). The patients were subjected to activation PET scanning by means of vibrotactile or visual stimulation. The results show that in most of the patients the important relation between the lesion and the sensorimotor cortex could be determined. The patient with a lesion in the occipital lobe had involvement of the entire visual cortex as judged by comparison with activated areas on the nonlesion side.
    Acta Neurochirurgica 02/1996; 138(6):684-94. · 1.55 Impact Factor
  • M Fredrikson, G Wik, H Fischer, J Andersson
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    ABSTRACT: Using positron emission tomography (PET) and [15O]butanol we studied regional cerebral blood flow (rCBF) to a visual snake stimulus before and after classical conditioning with an unconditioned electric shock delivered to the right hand. Measures of heart rate, electrodermal activity, state anxiety and subjective distress confirmed classical conditioning of physiological and subjective responses. Subcortically, conditioning increased rCBF bilaterally in the ventromedial thalamus, the posterior hypothalamus and the central grey of the midbrain. Cortically, rCBF increased in the left anterior and posterior cingulate gyrus, the left primary somatosensory cortex, the left premotor cortex and bilaterally in parietal areas. Thus, the functional organization of classical conditioning in humans involves autonomic, affective and attentive brain mechanisms.
    Neuroreport 01/1996; 7(1):97-101. · 1.40 Impact Factor
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    ABSTRACT: We performed positron emission tomography (PET) with [11C]deuterium-deprenyl in 9 patients with temporal lobe epilepsy (TLE) undergoing evaluation for possible epilepsy surgery. Seven patients had unilateral and 2 had bilateral mesiotemporal epileptic foci based on the preoperative investigation including ictal EEG discharges and PET with 2-[18F]fluoro-2-deoxyglucose (FDG). Deprenyl is an irreversible inhibitor of monoamine oxidase type B (MAO-B) with a very high affinity for the enzyme. In the brain, MAO-B is preferentially located in astrocytes, and a previous in vitro study showed increased binding of the ligand in sclerotic hippocampi. Dynamically acquired N-[methyl-11C]-a,a-di-deutero-L-deprenyl distribution in PET images were analyzed graphically, and the focus regions were assessed visually on the PET images. In addition, the accumulation rate and distribution volume of the tracer relative to the cerebellar cortex were measured in standardized homologous temporal regions by semiquantitative methods. Uptake of [11C]deuterium-deprenyl was significantly increased in the epileptogenic temporal lobes, both apparently and semiquantitatively. By calculating mean interlobar ratios, we identified the temporal lobe containing the epileptic focus in six unilateral cases. One case was ambiguous but was not falsely localized. The two bilateral cases were correctly identified as such. Our results suggest that PET with [11C]deuterium-deprenyl might be a useful method for identification of epileptogenic temporal lobes.
    Epilepsia 08/1995; 36(7):712-21. · 3.91 Impact Factor
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    ABSTRACT: The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[11C]methyl-benztropine) and dopaminergic receptor ligands selective for D1, D2, and D3 subtypes ([11C]SCH23390, N-[11C]methyl-spiperone, and (+)[11C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H(2)15O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [18F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[11C]methylbenztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [11C]SCH23390 (dopamine D1 receptor) binding. However, the k3 value for N-[11C]methyl-spiperone (dopamine D2 receptor) binding, which represents the association rate X Bmax value, was significantly decreased in the striatum. The uptake ratio of (+)[11C]UH232 (dopamine D3 receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D2 and D3 receptors selectively without markedly affecting dopamine D1 receptor binding. Furthermore, the changes in cholinergic and dopamine D2 and D3 receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.
    Journal of Neural Transmission 02/1995; 102(3):189-208. · 3.05 Impact Factor
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    ABSTRACT: In near-infrared spectroscopic studies during mental tasks such as problem solving and mental arithmetic, we found that 9 of 33 healthy volunteers showed decreases in both the regional cerebral blood flow (r-CBF) and oxygen consumption rate (CMRO2) in the frontal region of the dominant hemisphere. To confirm these unexpected observations, we performed simultaneous measurements by positron emission tomography (PET) and near-infrared spectroscopy (NIRS) in two such subjects. PET images also showed that CBF decreased within the presumptive area illuminated by near-infrared light during mental task. However, CBF decreased in almost all regions while the subject gave a correct answer. Thus, the questions arose: Are mental tasks always associated with increases in r-CBF and/or CMRO2?
    Neuroscience Letters 06/1994; · 2.03 Impact Factor

Publication Stats

813 Citations
61.29 Total Impact Points

Institutions

  • 1995–1998
    • Uppsala University Hospital
      • Department of Neurology
      Uppsala, Uppsala, Sweden
    • Uppsala Monitoring Centre
      Uppsala, Uppsala, Sweden
  • 1993–1997
    • Osaka Bioscience Institute
      Ōsaka, Ōsaka, Japan
  • 1991–1997
    • Uppsala University
      • Department of Radiology, Oncology and Radiation Science
      Uppsala, Uppsala, Sweden
  • 1996
    • Karolinska Institutet
      • Institutionen för klinisk neurovetenskap
      Solna, Stockholm, Sweden