| 1. |
- Kadir, Ahmadul, et al.
(författare)
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PET imaging of the in vivo brain acetylcholinesterase activity and nicotine binding in galantamine-treated patients with AD
- 2008
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 29:8, s. 1204-1217
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Tidskriftsartikel (refereegranskat)abstract
- The effect of galantamine treatment on cortical acetylcholinesterase (AChE) activity and nicotinic receptor binding was investigated by positron emission tomography (PET) in 18 patients with mild Alzheimer's disease (AD) in relation to galantamine concentration and the patients’ cognitive performances. The first 3 months of the study was of a randomized double-blind placebo-controlled design, during which 12 patients received galantamine (16–24 mg/day) and 6 patients the placebo, and this was followed by 9 months’ galantamine treatment in all patients. The patients underwent PET examinations to measure cortical AChE activity (11C-PMP) and 11C-nicotine binding. Neuropsychological tests were performed throughout the study. Inhibition (30–40%) of cortical AChE activity was observed after 3 weeks to 12 months of galantamine treatment. No significant change in mean cortical 11C-nicotine binding was observed during the study. 11C-Nicotine binding, however, positively correlated with plasma galantamine concentration. Both the changes of AChE activity and 11C-nicotine binding correlated positively with the results of a cognitive test of attention. In conclusion, galantamine caused sustained AChE inhibition for up to 12 months. At the individual level, the in vivo cortical AChE inhibition and 11C-nicotine binding were associated with changes in the attention domain of cognition rather than episodic memory.
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| 2. |
- Darreh-Shori, T., et al.
(författare)
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Inhibition of acetylcholinesterase in CSF versus brain assessed by 11C-PMP PET in AD patients treated with galantamine
- 2008
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 29:2, s. 168-184
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between acetylcholinesterase (AChE) activity in the CSF and brain of patients with Alzheimer's disease (AD) was investigated in 18 mild AD patients following galantamine treatment. The first 3 months of the study had a randomized double-blind placebo-controlled design, during which 12 patients received galantamine (16-24 mg/day) and six patients placebo. This was followed by 9 months Galantamine treatment in all patients. Activities and protein levels of both the "read-through" AChE (AChE-R) and the synaptic (AChE-S) variants in CSF were assessed in parallel together with the regional brain AChE activity by C-11-PMP and PET. The AChE-S inhibition was 30-36% in CSF, which correlated well with the in vivo AChE inhibition in the brain. No significant AChE inhibition was observed in the placebo group. The increased level of the AChE-R protein was 16% higher than that of AChE-S. Both the AChE inhibition and the increased level of AChE-R protein positively correlated with the patient's performance in cognitive tests associated with visuospatial ability and attention. In conclusion, AChE levels in CSF closely mirror in vivo brain AChE levels prior to and after treatment with the cholinesterase inhibitors. A positive cognitive response seems to dependent on the AChE inhibition level, which is balanced by an increased protein level of the AChE-R variant in the patients.
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| 6. |
- Erondu, Ngozi, et al.
(författare)
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Neuropeptide Y5 receptor antagonism does not induce clinically meaningful weight loss in overweight and obese adults
- 2006
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 4:4, s. 275-282
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide Y (NPY) is a potent orexigenic neuropeptide, and antagonism of NPY Y1 and NPY Y5 receptors (NPYxR) is considered a potentially important anti-obesity drug target. We tested the hypothesis that blockade of the NPY5R will lead to weight loss in humans using MIK-0557, a potent, highly selective, orally active NPY5R antagonist. The initial series of experiments reported herein, including a multiple-dose positron-emission tomography study and a 12 week proof-of concept/dose-ranging study, suggested an optimal MK-0557 dose of 1 mg/day. The hypothesis was then tested in a 52 week, multicenter, randomized, double-blind, placebo-controlled trial involving 1661 overweight and obese patients. Although statistically significant at 52 weeks, the magnitude of induced weight loss was not clinically meaningful. These observations provide the first clinical insight into the human NPY-energy homeostatic pathway and suggest that solely targeting the NPY5R in future drug development programs is unlikely to produce therapeutic efficacy.
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| 7. |
- Furmark, Tomas, et al.
(författare)
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Elevated uptake of [C-11] 5-hydroxy-tryptophan in the amygdala in patients with social anxiety disorder : a PET study
- 2009
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Ingår i: Biol. Psychiatry 65, 126S-127S. ; , s. 421-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Social anxiety disorder (SAD) is associated with amygdala hyperresponsivity and imbalances in serotonergic neurotransmission. We have previously noted altered uptake of carbon-11 labelled 5-hydroxytryptophan (5-HTP) in a small sample of patients with SAD, suggesting deficiencies in presynaptic serotonin synthesis. In the present study, positron emission tomography (PET) was used to assess uptake of [11C]5-HTP in a larger sample of patients with SAD compared with age and sex-matched healthy controls. Methods: PET-data were available for 17 patients (8 females, age 33±8 years) diagnosed with SAD and for 17 healthy controls (9 females, age 35±10 years). Accumulation of the [11C]5-HTP tracer was assessed at Uppsala Imanet during 60 minutes in the resting state. Parametric images were generated using the graphical reference Patlak method assuming irreversible trapping of [11C]5-HTP from 11-60 minutes. Cerebellum was selected as reference region after correction for the decarboxylation rate of [11C]5-HTP. Exploratory and amygdala focused analyses were performed using statistical parametric mapping (SPM2). Results: Patients with SAD had significantly higher [11C]5-HTP uptake than controls in several regions including the superior, medial and inferior frontal gyrus, anterior cingulate cortex, hippocampus and lentiform nucleus, all in the left hemisphere. Region of interest analyses also revealed significantly higher uptake (SAD > controls) in the left (x-28 y-4 z-12; T=3.16) and right (x24 y1 z-15; T=2.82) amygdala (p<0.05 corrected). Conclusions: Higher [11C]5-HTP uptake, suggesting an elevated serotonin synthesis rate, was noted in patients with SAD compared to healthy controls predominantly in frontal and temporal regions including the amygdala.
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| 11. |
- Richter, H. O, et al.
(författare)
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Neuroanatomical correlates of voluntary inhibition of accommodation/vergence under monocular open-loop viewing conditions.
- 2005
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 21:11, s. 3077-3088
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work is to identify human neural circuits involved in inhibition of accommodation/vergence by contrasting the cortical functions subservient to negative voluntary accommodation/vergence (NVA) with those evoked by active fixation in darkness (FIX). Five subjects with normal corrected acuity were studied using positron emission tomography and the H O bolus technique. The dominant right eye viewed a laser speckle pattern (633 nm) whose direction and velocity of motion were determined by the refractive state of the eye. The speckle pattern was presented at a distance of 1.8 m (0.55 D). The non-dominant eye was patched. Subjects performed two tasks counterbalanced for order effects: (i) attempted fixation on the remembered target in darkness with the dominant eye open and ‘fixating’; and (ii) voluntary reduction of the laser speckle flow during each alternate 20-s epoch when a convex +2.0 D lens was placed in front of the right eye causing the speckle pattern to move downwards at 3 °/s. Comparison of the condition of NVA with the condition of FIX indicated widespread occipital activation. Decreases in absolute regional cerebral blood flow occurred in the superior parietal cortex (BA 5), frontal cortex (BA 8 and 10) and within the postcentral/precentral gyrus (BA 1/2/3/4) bilaterally where deactivation clusters eclipsed the presumed neck and shoulder areas. Negative accommodation/vergence appears to be driven by a reduction of parasympathetic tone, and has the effect of shutting down brain regions known to be involved in regulating visual search as well as a centrally controlled eye–head–neck–shoulder motor programme responsible for posturing gaze.
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| 12. |
- Stefanova, E, et al.
(författare)
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Longitudinal PET evaluation of cerebral glucose metabolism in rivastigmine treated patients with mild Alzheimer’s disease.
- 2006
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Ingår i: Journal of Neural Transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 113:2, s. 205-218
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Tidskriftsartikel (refereegranskat)abstract
- In this study 11 patients with mild Alzheimer’s disease (AD) were treated with the cholinesterase inhibitor rivastigmine (mean dose 8.6 ± 1.3’mg) for 12 months and underwent positron emission tomography (PET) studies of cerebral glucose metabolism (CMRglc) and neuropsychological testing at baseline and after 12 months. An untreated group of 10 AD patients served as control group. While the untreated AD patients showed a significant decline of CMRglc in the temporo-parietal and frontal cortical regions after 12 months follow-up the rivastigmine-treated patients showed no decline in CMRglc in corresponding cortical brain regions. Furthermore, a significant dose-related increase in CMRglc was recorded in the right frontal association region after 12 months rivastigmine treatment. A positive correlation was observed between changes in CMRglc and several cognitive tests in patients receiving higher doses (10.5–12’mg) of rivastigmine. These results suggest a stabilization effect of rivastigmine on CMRglc in mild AD patients receiving long-term rivastigmine treatment.
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| 13. |
- Wallén-Mackenzie, Åsa, et al.
(författare)
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Restricted cortical and amygdaloid removal of vesicular glutamate transporter 2 in preadolescent mice impacts dopaminergic activity and neuronal circuitry of higher brain function.
- 2009
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Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401 .- 0270-6474. ; 29:7, s. 2238-51
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Tidskriftsartikel (refereegranskat)abstract
- A major challenge in neuroscience is to resolve the connection between gene functionality, neuronal circuits, and behavior. Most, if not all, neuronal circuits of the adult brain contain a glutamatergic component, the nature of which has been difficult to assess because of the vast cellular abundance of glutamate. In this study, we wanted to determine the role of a restricted subpopulation of glutamatergic neurons within the forebrain, the Vglut2-expressing neurons, in neuronal circuitry of higher brain function. Vglut2 expression was selectively deleted in the cortex, hippocampus, and amygdala of preadolescent mice, which resulted in increased locomotor activity, altered social dominance and risk assessment, decreased sensorimotor gating, and impaired long-term spatial memory. Presynaptic VGLUT2-positive terminals were lost in the cortex, striatum, nucleus accumbens, and hippocampus, and a downstream effect on dopamine binding site availability in the striatum was evident. A connection between the induced late-onset, chronic reduction of glutamatergic neurotransmission and dopamine signaling within the circuitry was further substantiated by a partial attenuation of the deficits in sensorimotor gating by the dopamine-stabilizing antipsychotic drug aripiprazole and an increased sensitivity to amphetamine. Somewhat surprisingly, given the restricted expression of Vglut2 in regions responsible for higher brain function, our analyses show that VGLUT2-mediated neurotransmission is required for certain aspects of cognitive, emotional, and social behavior. The present study provides support for the existence of a neurocircuitry that connects changes in VGLUT2-mediated neurotransmission to alterations in the dopaminergic system with schizophrenia-like behavioral deficits as a major outcome.
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| 16. |
- Åhs, Fredrik, et al.
(författare)
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Hypothalamic blood flow correlates positively with stress-induced cortisol levels in subjects with social anxiety disorder
- 2006
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Ingår i: Psychosomatic Medicine. - : Ovid Technologies (Wolters Kluwer Health). - 0033-3174 .- 1534-7796. ; 68:6, s. 859-862
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The adrenal excretion of cortisol in animals is dependent on the production of corticotropin-releasing factor in the paraventricular nucleus of the hypothalamus. The a priori hypothesis of this study was that hypothalamic regional cerebral blood flow (rCBF) would correlate positively with salivary cortisol levels in patients with social anxiety disorder (SAD) during anxiety provocation. Another objective was to evaluate whether salivary cortisol levels correlated with rCBF in other brain areas. Method: Regional CBF was measured with oxygen-15-labeled water and positron emission tomography during a public speaking task before and after placebo treatment in 12 subjects with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-defined SAD. Cortisol concentrations in saliva were measured 15 minutes after the task. The a priori hypothesis of a salivary cortisol-dependent activation of the hypothalamus was studied with region-of-interest analysis. In addition, the covariation between rCBF and salivary cortisol was studied in the whole brain using the general linear model. Results: The region-of-interest analysis revealed a positive correlation between salivary cortisol and hypothalamic rCBF. In the whole brain analysis, a positive covariation between rCBF and salivary cortisol levels was found in a midbrain cluster encompassing the hypothalamus with its statistical maximum in the mamillary bodies. Negative covariations were observed in the medial prefrontal cortex as well as in the motor and premotor cortices. Conclusion: Like in animals, stress-induced cortisol excretion in humans may be inhibited by activity in the medial prefrontal cortex and enhanced by activity in the hypothalamus.
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