The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Lars Farde - One of the best experts on this subject based on the ideXlab platform.
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Differentiation of extrastriatal dopamine D2 Receptor Density and affinity in the human brain using PET.
NeuroImage, 2004Co-Authors: Hans Olsson, Christer Halldin, Lars FardeAbstract:Dopaminergic neurotransmission in extrastriatal regions may play a crucial role in the pathophysiology and treatment of neuropsychiatric disorders. The high-affinity radioligands [(11)C]FLB 457, [(123)I]epidepride, and [(18)F]fallypride are now used in clinical studies to measure these low-Density Receptor populations in vivo. However, a single determination of the regional binding potential (BP) does not differentiate Receptor Density (B(max)) from the apparent affinity (K(D)). In this positron emission tomography (PET) study, we measured extrastriatal dopamine D2 Receptor Density (B(max)) and apparent affinity (K(D)) in 10 healthy subjects using an in vivo saturation approach. Each subject participated in two to three PET measurements with different specific radioactivity of [(11)C]FLB 457. The commonly used simplified reference tissue model (SRTM) was used in a comparison of BP values with the B(max) values obtained from the saturation analysis. The calculated regional Receptor Density values were of the same magnitude (0.33-1.68 nM) and showed the same rank order as reported from postmortem studies, that is, in descending order thalamus, lateral temporal cortex, anterior cinguli, and frontal cortex. The affinity ranged from 0.27 to 0.43 nM, that is, approximately 10-20 times the value found in vitro (20 pM). The area under the cerebellar time activity curve (TAC) was slightly lower (11 +/- 8%, mean +/- SD, P = 0.004, n = 10) after injection of low as compared with high specific radioactivity, indicating sensitivity to the minute Density of dopamine D2 Receptors in the this region. The results of the present study support that dopamine D2 Receptor Density and affinity can be differentiated in low-Density regions using a saturation approach. There was a significant (P < 0.001) correlation between the binding potential calculated with SRTM and the Receptor Density (B(max)), which supports the use of BP in clinical studies where differentiation of B(max) and K(D) is not required. In such studies, the mass of FLB 457 has to be less than 0.5 microg injected to avoid a mass effect of the radioligand itself.
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polymorphisms in the dopamine d2 Receptor gene and their relationships to striatal dopamine Receptor Density of healthy volunteers
Molecular Psychiatry, 1999Co-Authors: Erik G. Jönsson, Y. Nakashima, Peter Propping, Lars Farde, Frank Grunhage, Markus M Nothen, Göran SedvallAbstract:The Density of striatal dopamine D2 Receptors has been shown to vary considerably among healthy subjects.1 This variability might be due to genetic or environmental factors. In the present analysis we searched for relationships between dopamine D2 Receptor gene (DRD2) polymorphisms and striatal dopamine D2 Receptor Density in vivo, as measured by positron emission tomography and [11C]raclopride in 56 healthy subjects. There was a significant association between presence of a putative functional DRD2 promoter allele (−141C Del) and high striatal dopamine Receptor Density (t = 2.32, P = 0.02). In agreement with some previous studies2–4 the presence of the DRD2 TaqIA1 allele was associated with measures of low dopamine Receptor Density (t = 2.58, P = 0.01). Also the DRD2 TaqIB1 allele was associated with low dopamine Receptor Density (t = 2.58, P = 0.01) wheras there was no significant relationship between another common silent intronic DRD2 short tandem repeat polymorphism (STRP) and striatal dopamine D2 Receptor Density. The results suggest that DRD2 genotypes may participate differentially in the regulation of striatal dopamine D2 Receptor Density in healthy human subjects. The results should be interpreted with caution because of the limited sample size.
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variability in d2 dopamine Receptor Density and affinity a pet study with 11c raclopride in man
Synapse, 1995Co-Authors: Lars Farde, Stefan Pauli, Hakan Hall, Christer HalldinAbstract:The variability of D2-dopamine Receptor binding parameters in man was determined using Positron Emission Tomography (PET) and [11C]raclopride. A saturation analysis based on five PET-experiments was performed in each of ten men and ten women. The mean Density of D2-dopamine Receptors (Bmax) was 28 ± 6.9 pmol/ml (mean ± S.D.) and the apparent affinity (Kdapp)9.1 ± 1.9 pmol/ml. The Hill coefficient was in all subjects close to unity (nH: 0.999 ± 0.020), thereby indicating binding to a homogeneous class of Receptors. No significant differences between males and females were found in Bmax or Kdapp. The interindividual difference in Bmaxwas statistically significant (α = 0.01). The difference in Kdapp was not significant. Upregulation of the Receptor Density (Bmax) has been widely discussed as a mechanism for increased dopaminergic neurotransmission in schizophrenia. This study indicates that Receptor Density varies considerably in a group of healthy subjects. © 1995 Wiley-Liss, Inc.
Göran Sedvall - One of the best experts on this subject based on the ideXlab platform.
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polymorphisms in the dopamine d2 Receptor gene and their relationships to striatal dopamine Receptor Density of healthy volunteers
Molecular Psychiatry, 1999Co-Authors: Erik G. Jönsson, Y. Nakashima, Peter Propping, Lars Farde, Frank Grunhage, Markus M Nothen, Göran SedvallAbstract:The Density of striatal dopamine D2 Receptors has been shown to vary considerably among healthy subjects.1 This variability might be due to genetic or environmental factors. In the present analysis we searched for relationships between dopamine D2 Receptor gene (DRD2) polymorphisms and striatal dopamine D2 Receptor Density in vivo, as measured by positron emission tomography and [11C]raclopride in 56 healthy subjects. There was a significant association between presence of a putative functional DRD2 promoter allele (−141C Del) and high striatal dopamine Receptor Density (t = 2.32, P = 0.02). In agreement with some previous studies2–4 the presence of the DRD2 TaqIA1 allele was associated with measures of low dopamine Receptor Density (t = 2.58, P = 0.01). Also the DRD2 TaqIB1 allele was associated with low dopamine Receptor Density (t = 2.58, P = 0.01) wheras there was no significant relationship between another common silent intronic DRD2 short tandem repeat polymorphism (STRP) and striatal dopamine D2 Receptor Density. The results suggest that DRD2 genotypes may participate differentially in the regulation of striatal dopamine D2 Receptor Density in healthy human subjects. The results should be interpreted with caution because of the limited sample size.
I. Hui Lee - One of the best experts on this subject based on the ideXlab platform.
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Correlation between striatal dopamine D2 Receptor Density and neuroticism in community volunteers.
Psychiatry research, 2005Co-Authors: I. Hui Lee, Yen Kuang Yang, Tzung Lieh Yeh, Chwen Cheng Cheng, Po See Chen, Nan Tsing ChiuAbstract:Abstract The central dopaminergic system, as well as the central serotonergic system, has been reported to be correlated with higher neuroticism. The present study examined the relationship between striatal dopamine D 2 Receptor Density and neuroticism. Neuroticism was assessed with the Maudsley Personality Inventory, and psychiatric morbidity was evaluated with both the Mini International Neuropsychiatric Interview and the Hamilton Depression Rating Scale (HAM-D). Single photon emission computed tomography with [ 123 I]iodo-benzamide was used to measure striatal dopamine D 2 Receptor Density. HAM-D scores and psychiatric morbidity in high-neuroticism individuals were higher than in low-neuroticism individuals. Moreover, striatal dopamine D 2 Receptor densities were significantly correlated with the neuroticism score of the 41 subjects. The central dopaminergic system may play an important role in the neurobiological characteristics of neuroticism.
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Correlation between fine motor activity and striatal dopamine D2 Receptor Density in patients with schizophrenia and healthy controls.
Psychiatry research, 2003Co-Authors: Yen Kuang Yang, Nan Tsing Chiu, Chwen Cheng Chen, Mitchell Chen, Tzung Lieh Yeh, I. Hui LeeAbstract:Abstract Striatal dopamine D 2 Receptor Density is an important indicator of many neuropsychiatric disorders and also of motor activity. This study examined the relationship between a fine motor task (finger tapping test, FTT) and striatal D 2 dopamine Receptor Density by examining 20 healthy volunteers and 20 schizophrenic patients. Striatal D 2 Receptor Density was determined with single photon emission computed tomography using [ 123 I]IBZM (iodo-benzamide). The correlation between the FTT score and striatal D 2 Receptor Density was statistically significant not only in the patient group but also in healthy controls. The FTT scores and striatal D 2 Receptor Density were lower in medicated patients than that in healthy controls. Compared with the Simpson–Angus Scale scores, the FTT scores were more strongly associated with striatal D 2 Receptor Density. The use of neuroleptic medication seemed to influence the associations between FTT scores and striatal D 2 Receptor Density in the patient group. The FTT scores and striatal D 2 Receptor Density were age-sensitive in healthy controls. FTT may be a more sensitive tool for detecting neuroleptic-induced motor impairment in patients with schizophrenia. The sensitivity of the FTT to age and neuroleptic effects may be explained in part by a decline in dopamine D 2 Density.
Nan Tsing Chiu - One of the best experts on this subject based on the ideXlab platform.
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Correlation between striatal dopamine D2 Receptor Density and neuroticism in community volunteers.
Psychiatry research, 2005Co-Authors: I. Hui Lee, Yen Kuang Yang, Tzung Lieh Yeh, Chwen Cheng Cheng, Po See Chen, Nan Tsing ChiuAbstract:Abstract The central dopaminergic system, as well as the central serotonergic system, has been reported to be correlated with higher neuroticism. The present study examined the relationship between striatal dopamine D 2 Receptor Density and neuroticism. Neuroticism was assessed with the Maudsley Personality Inventory, and psychiatric morbidity was evaluated with both the Mini International Neuropsychiatric Interview and the Hamilton Depression Rating Scale (HAM-D). Single photon emission computed tomography with [ 123 I]iodo-benzamide was used to measure striatal dopamine D 2 Receptor Density. HAM-D scores and psychiatric morbidity in high-neuroticism individuals were higher than in low-neuroticism individuals. Moreover, striatal dopamine D 2 Receptor densities were significantly correlated with the neuroticism score of the 41 subjects. The central dopaminergic system may play an important role in the neurobiological characteristics of neuroticism.
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Correlation between fine motor activity and striatal dopamine D2 Receptor Density in patients with schizophrenia and healthy controls.
Psychiatry research, 2003Co-Authors: Yen Kuang Yang, Nan Tsing Chiu, Chwen Cheng Chen, Mitchell Chen, Tzung Lieh Yeh, I. Hui LeeAbstract:Abstract Striatal dopamine D 2 Receptor Density is an important indicator of many neuropsychiatric disorders and also of motor activity. This study examined the relationship between a fine motor task (finger tapping test, FTT) and striatal D 2 dopamine Receptor Density by examining 20 healthy volunteers and 20 schizophrenic patients. Striatal D 2 Receptor Density was determined with single photon emission computed tomography using [ 123 I]IBZM (iodo-benzamide). The correlation between the FTT score and striatal D 2 Receptor Density was statistically significant not only in the patient group but also in healthy controls. The FTT scores and striatal D 2 Receptor Density were lower in medicated patients than that in healthy controls. Compared with the Simpson–Angus Scale scores, the FTT scores were more strongly associated with striatal D 2 Receptor Density. The use of neuroleptic medication seemed to influence the associations between FTT scores and striatal D 2 Receptor Density in the patient group. The FTT scores and striatal D 2 Receptor Density were age-sensitive in healthy controls. FTT may be a more sensitive tool for detecting neuroleptic-induced motor impairment in patients with schizophrenia. The sensitivity of the FTT to age and neuroleptic effects may be explained in part by a decline in dopamine D 2 Density.
Erik G. Jönsson - One of the best experts on this subject based on the ideXlab platform.
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polymorphisms in the dopamine d2 Receptor gene and their relationships to striatal dopamine Receptor Density of healthy volunteers
Molecular Psychiatry, 1999Co-Authors: Erik G. Jönsson, Y. Nakashima, Peter Propping, Lars Farde, Frank Grunhage, Markus M Nothen, Göran SedvallAbstract:The Density of striatal dopamine D2 Receptors has been shown to vary considerably among healthy subjects.1 This variability might be due to genetic or environmental factors. In the present analysis we searched for relationships between dopamine D2 Receptor gene (DRD2) polymorphisms and striatal dopamine D2 Receptor Density in vivo, as measured by positron emission tomography and [11C]raclopride in 56 healthy subjects. There was a significant association between presence of a putative functional DRD2 promoter allele (−141C Del) and high striatal dopamine Receptor Density (t = 2.32, P = 0.02). In agreement with some previous studies2–4 the presence of the DRD2 TaqIA1 allele was associated with measures of low dopamine Receptor Density (t = 2.58, P = 0.01). Also the DRD2 TaqIB1 allele was associated with low dopamine Receptor Density (t = 2.58, P = 0.01) wheras there was no significant relationship between another common silent intronic DRD2 short tandem repeat polymorphism (STRP) and striatal dopamine D2 Receptor Density. The results suggest that DRD2 genotypes may participate differentially in the regulation of striatal dopamine D2 Receptor Density in healthy human subjects. The results should be interpreted with caution because of the limited sample size.
