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D2 occupancy

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https://www.readbyqxmd.com/read/29346639/comparison-of-dopamine-d3-and-d2-receptor-occupancies-by-a-single-dose-of-blonanserin-in-healthy-subjects-a-positron-emission-tomography-study-with-11c-phno
#1
Amane Tateno, Takeshi Sakayori, Woo-Chan Kim, Kazuyoshi Honjo, Haruo Nakayama, Ryosuke Arakawa, Yoshiro Okubo
Background: Blockade of D3 receptor, a member of the dopamine D2-like receptor family, has been suggested as a possible medication for schizophrenia. Blonanserin has high affinity in vitro for D3 as well as D2 receptors. We investigated whether a single dose of 12 mg blonanserin, which was within the daily clinical dose range (i.e., 8-24 mg) for the treatment of schizophrenia, occupies D3 as well as D2 receptors in healthy subjects. Methods: Six healthy males (mean 35...
January 13, 2018: International Journal of Neuropsychopharmacology
https://www.readbyqxmd.com/read/29334326/predicting-the-dopamine-d2-receptor-occupancy-of-ropinirole-in-rats-using-positron-emission-tomography-and-pharmacokinetic-pharmacodynamic-modeling
#2
Chenrong Huang, Ziteng Wang, Linsheng Liu, Xiaoxue Liu, Ji Dong, Qingqing Xu, Bin Zhang, Liyan Miao
The purpose of this study was to measure dopamine D2/3 receptor occupancy (RO) as a marker of the clinical efficacy of ropinirole in rats via positron emission tomography (PET) using 18F-fallypride as the radiotracer and to explore the relationship between dopamine RO and the plasma concentration of ropinirole via pharmacokinetic-pharmacodynamic modeling. Plasma was collected from 16 rats treated with one of four doses of ropinirole. For the time-dependent study, the data of 16 rats in the 15 mg/kg dose group at four time points were averaged, and another 24 rats were divided into three dose groups (5 mg/kg, 30 mg/kg and 60 mg/kg) for the dose-dependent study; the animals were assessed via 18F-fallypride PET scans...
January 15, 2018: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/29229351/evaluation-of-the-measuring-methods-of-the-spinal-canal-occupation-rate-in-thoracic-ossification-of-ligamentum-flavum
#3
Sheng-Yuan Zhou, Bo Yuan, Chuang Qian, Xiong-Sheng Chen, Lian-Shun Jia
OBJECTIVE: The degree of hypertrophy of thoracic ossification of ligamentum flavum (TOLF) is related to the severity of the myelopathy. There is no uniform measuring method to calculate the spinal canal occupation ratio (COR) of TOLF simply and effectively. The study was to determine an appropriate measuring method to calculate the COR of TOLF. METHODS: A total of 37 computerized tomography (CT) cross-sectional imaging scans (bone window) from 22 patients were analyzed retrospectively in this study...
December 8, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/29226628/modeling-of-prolactin-response-following-dopamine-d2-receptor-antagonists-in-rats-can-it-be-translated-to-clinical-dosing
#4
Amit Taneja, An Vermeulen, Dymphy R H Huntjens, Meindert Danhof, Elizabeth C M De Lange, Johannes H Proost
Prolactin release is a side effect of antipsychotic therapy with dopamine antagonists, observed in rats as well as humans. We examined whether two semimechanistic models could describe prolactin response in rats and subsequently be translated to predict pituitary dopamine D2 receptor occupancy and plasma prolactin concentrations in humans following administration of paliperidone or remoxipride. Data on male Wistar rats receiving single or multiple doses of risperidone, paliperidone, or remoxipride was described by two semimechanistic models, the precursor pool model and the agonist-antagonist interaction model...
December 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/29223715/development-of-two-fluorine-18-labeled-pet-radioligands-targeting-pde10a-and-in-vivo-pet-evaluation-in-nonhuman-primates
#5
Vladimir Stepanov, Akihiro Takano, Ryuji Nakao, Nahid Amini, Shotaro Miura, Tomoaki Hasui, Haruhide Kimura, Takahiko Taniguchi, Christer Halldin
INTRODUCTION: Phosphodiesterase 10A (PDE10A) is a member of the PDE enzyme family that degrades cyclic adenosine and guanosine monophosphates (cAMP and cGMP). Based on the successful development of [11C]T-773 as PDE10A positron emission tomography (PET) radioligand, in this study our aim was to develop and evaluate fluorine-18 analogs of [11C]T-773. METHODS: [18F]FM-T-773-d2 and [18F]FE-T-773-d4 were synthesized from the same precursor used for 11C-labeling of T-773 in a two-step approach via 18F-fluoromethylation and 18F-fluoroethylation, respectively, using corresponding deuterated synthons...
October 23, 2017: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29110353/amotivation-is-associated-with-smaller-ventral-striatum-volumes-in-older-patients-with-schizophrenia
#6
Fernando Caravaggio, Gagan Fervaha, Yusuke Iwata, Eric Plitman, Jun Ku Chung, Shinichiro Nakajima, Wanna Mar, Philip Gerretsen, Julia Kim, M Mallar Chakravarty, Benoit Mulsant, Bruce Pollock, David Mamo, Gary Remington, Ariel Graff-Guerrero
OBJECTIVE: Motivational deficits are prevalent in patients with schizophrenia, persist despite antipsychotic treatment, and predict long-term outcomes. Evidence suggests that patients with greater amotivation have smaller ventral striatum (VS) volumes. We wished to replicate this finding in a sample of older, chronically medicated patients with schizophrenia. Using structural imaging and positron emission tomography, we examined whether amotivation uniquely predicted VS volumes beyond the effects of striatal dopamine D2/3 receptor (D2/3 R) blockade by antipsychotics...
November 7, 2017: International Journal of Geriatric Psychiatry
https://www.readbyqxmd.com/read/29106979/development-of-a-population-pharmacokinetic-model-to-predict-brain-distribution-and-dopamine-d2-receptor-occupancy-of-raclopride-in-non-anesthetized-rat
#7
Yin Cheong Wong, Trayana Ilkova, Rob C van Wijk, Robin Hartman, Elizabeth C M de Lange
BACKGROUND: Raclopride is a selective antagonist of the dopamine D2 receptor. It is one of the most frequently used in vivo D2 tracers (at low doses) for assessing drug-induced receptor occupancy (RO) in animals and humans. It is also commonly used as a pharmacological blocker (at high doses) to occupy the available D2 receptors and antagonize the action of dopamine or drugs on D2 in preclinical studies. The aims of this study were to comprehensively evaluate its pharmacokinetic (PK) profiles in different brain compartments and to establish a PK-RO model that could predict the brain distribution and RO of raclopride in the freely moving rat using a LC-MS based approach...
November 4, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29016875/occupancy-of-norepinephrine-transporter-by-duloxetine-in-human-brains-measured-by-positron-emission-tomography-with-s-s-18f-fmener-d2
#8
Sho Moriguchi, Harumasa Takano, Yasuyuki Kimura, Tomohisa Nagashima, Keisuke Takahata, Manabu Kubota, Soichiro Kitamura, Tatsuya Ishii, Masanori Ichise, Ming-Rong Zhang, Hitoshi Shimada, Masaru Mimura, Jeffrey H Meyer, Makoto Higuchi, Tetsuya Suhara
Background: The norepinephrine transporter in the brain has been targeted in the treatment of psychiatric disorders. Duloxetine is a serotonin and norepinephrine reuptake inhibitor that has been widely used for the treatment of depression. However, the relationship between dose and plasma concentration of duloxetine and norepinephrine transporter occupancy in the human brain has not been determined. In this study, we examined norepinephrine transporter occupancy by different doses of duloxetine...
August 3, 2017: International Journal of Neuropsychopharmacology
https://www.readbyqxmd.com/read/28858444/a-population-approach-to-guide-amisulpride-dose-adjustments-in-older-patients-with-alzheimer-s-disease
#9
Suzanne Reeves, Julie Bertrand, Emma McLachlan, Fabrizia D'Antonio, Stuart Brownings, Akshay Nair, Suki Greaves, Alan Smith, Joel T Dunn, Paul Marsden, Robert Kessler, Hiroyuki Uchida, David Taylor, Robert Howard
OBJECTIVE: We have previously reported high dopamine D2/3 receptor occupancies at low amisulpride concentrations in older people with Alzheimer's disease (AD), during off-label treatment of AD-related psychosis. This post hoc analysis explored pharmacokinetic (concentration) and pharmacodynamic (prolactin, D2/3 occupancy) contributions to symptom reduction and extrapyramidal side effects (EPS) to inform AD-specific dose adjustments. METHODS: Population pharmacokinetic-pharmacodynamic models were developed by combining pharmacokinetic data from a phase 1 study in 20 healthy older people with pharmacokinetic prolactin, [¹⁸F]fallypride D2/3 receptor imaging, and clinical outcome data from 28 older patients prescribed open amisulpride (25-75 mg/d) to treat AD-related psychosis...
July 2017: Journal of Clinical Psychiatry
https://www.readbyqxmd.com/read/28839266/neutron-crystallography-of-photoactive-yellow-protein-reveals-unusual-protonation-state-of-arg52-in-the-crystal
#10
Kento Yonezawa, Nobutaka Shimizu, Kazuo Kurihara, Yoichi Yamazaki, Hironari Kamikubo, Mikio Kataoka
Because of its high pKa, arginine (Arg) is believed to be protonated even in the hydrophobic environment of the protein interior. However, our neutron crystallographic structure of photoactive yellow protein, a light sensor, demonstrated that Arg52 adopts an electrically neutral form. We also showed that the hydrogen bond between the chromophore and Glu46 is a so-called low barrier hydrogen bond (LBHB). Because both the neutral Arg and LBHB are unusual in proteins, these observations remain controversial. To validate our findings, we carried out neutron crystallographic analysis of the E46Q mutant of PYP...
August 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28643852/therapeutic-d2-3-receptor-occupancies-and-response-with-low-amisulpride-blood-concentrations-in-very-late-onset-schizophrenia-like-psychosis-vloslp
#11
Suzanne Reeves, Kate Eggleston, Elizabeth Cort, Emma McLachlan, Stuart Brownings, Akshay Nair, Suki Greaves, Alan Smith, Joel Dunn, Paul Marsden, Robert Kessler, David Taylor, Julie Bertrand, Robert Howard
OBJECTIVE: Antipsychotic drug sensitivity in very late-onset schizophrenia-like psychosis (VLOSLP) is well documented, but poorly understood. This study aimed to investigate blood drug concentration, D2/3 receptor occupancy and outcome in VLOSLP during open amisulpride prescribing, and compare this with Alzheimer's disease (AD). METHODS: Blood drug concentration, prolactin, symptoms and extrapyramidal side-effects (EPS) were serially assessed during dose titration...
June 23, 2017: International Journal of Geriatric Psychiatry
https://www.readbyqxmd.com/read/28541050/crystal-structure-of-pr3mgni14dx-studied-by-in-situ-neutron-diffraction
#12
Kenji Iwase, Kazuhiro Mori, Naoyoshi Terashita, Suguru Tashiro, Tetsuya Suzuki
The crystal structure of Pr3MgNi14D18 was determined by neutron diffraction. The determined structure of Pr3MgNi14D18 consisted of 89.0% Gd2Co7-type structure and 11.0% PuNi3-type structure. The lattice parameters of a and c of Gd2Co7-type structure were refined at 0.52903(7) nm and 3.90179(1) nm. The deuterium atoms were distributed among nine deuterium sites in both the CaCu5-type and MgZn2-type cells. The D2 occupancy in the Pr2Ni4 octahedral sites of the CaCu5-type cell was the largest (0.75) when compared with the other deuterium sites (<0...
May 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28486094/a-pharmacodynamic-modelling-and-simulation-study-identifying-gender-differences-of-daily-olanzapine-dose-and-dopamine-d2-receptor-occupancy
#13
Andy R Eugene, Jolanta Masiak
BACKGROUND: Gender differences in treatment response rates for patients treated with antipsychotics are known. However, the literature lacks a pharmacodynamic model to allow for gender-based clinical trial simulations from modelling parameters for Olanzapine and dopamine D2 receptor occupancy. Thus, the primary aim of this analysis is to test and quantify the effect of gender on the pharmacodynamics of Olanzapine. METHODS: Population pharmacodynamic modelling was performed using non-linear mixed effects modelling in MONOLIX, while the Clinical Trial Simulations were performed using R for statistical programming...
August 2017: Nordic Journal of Psychiatry
https://www.readbyqxmd.com/read/28412910/aripiprazole-a-drug-that-displays-partial-agonism-and-functional-selectivity
#14
Erin W Tuplin, Matthew R Holahan
The treatment of schizophrenia is challenging due to the wide range of symptoms (positive, negative, cognitive) associated with the disease. Typical antipsychotics that antagonize D2 receptors are effective in treating positive symptoms, but extrapyramidal side-effects (EPS) are a common occurrence. Atypical antipsychotics targeting 5-TH2A and D2 receptors are more effective at treating cognitive and negative symptoms compared to typical antipsychotics, but these drugs also result in side-effects such as metabolic syndromes...
April 13, 2017: Current Neuropharmacology
https://www.readbyqxmd.com/read/28395348/exposure-assessment-in-a-single-walled-carbon-nanotube-primary-manufacturer
#15
Serge Kouassi, Cyril Catto, Claude Ostiguy, Gilles L'Espérance, Jens Kroeger, Maximilien Debia
Objectives: This study was aimed at documenting and characterizing occupational exposure to single-walled carbon nanotubes (SWCNTs) generated in a primary manufacturing plant. It also compared various strategies of exposure monitoring. Methods: A 6-day measurement protocol was scheduled (D1-D6) including both (i) quasi-personal monitoring with an array of direct reading instruments (DRIs) and (ii) offline electron microscopy analyses of surface and breathing zone filter-based samples...
March 1, 2017: Annals of Work Exposures and Health
https://www.readbyqxmd.com/read/28365375/preclinical-molecular-imaging-of-glutamatergic-and-dopaminergic-neuroreceptor-kinetics-in-obsessive-compulsive-disorder
#16
S Servaes, D Glorie, J Verhaeghe, S Stroobants, S Staelens
BACKGROUND: Molecular neuroimaging was applied in the quinpirole rat model for compulsive checking in OCD to visualize the D2- and mGluR5-receptor occupancy with Raclopride and ABP-688 microPET/CT. METHODS: Animals (n=48) were exposed to either saline (CTRL; 1mL/kg) or quinpirole (QP; dopamine D2-agonist, 0.5mg/kg) in a single injection (RAC and ABP acute groups) or twice-weekly during 7weeks (chronic group). Animals underwent PET/CT after the 1st injection (acute) or before initial exposure and following the 10th injection in week 5 (chronic)...
March 30, 2017: Progress in Neuro-psychopharmacology & Biological Psychiatry
https://www.readbyqxmd.com/read/28334978/therapeutic-window-of-dopamine-d2-3-receptor-occupancy-to-treat-psychosis-in-alzheimer-s-disease
#17
Suzanne Reeves, Emma McLachlan, Julie Bertrand, Fabrizia D Antonio, Stuart Brownings, Akshay Nair, Suki Greaves, Alan Smith, David Taylor, Joel Dunn, Paul Marsden, Robert Kessler, Robert Howard
See Caravaggio and Graff-Guerrero (doi:10.1093/awx023) for a scientific commentary on this article.Antipsychotic drugs, originally developed to treat schizophrenia, are used to treat psychosis, agitation and aggression in Alzheimer's disease. In the absence of dopamine D2/3 receptor occupancy data to inform antipsychotic prescribing for psychosis in Alzheimer's disease, the mechanisms underpinning antipsychotic efficacy and side effects are poorly understood. This study used a population approach to investigate the relationship between amisulpride blood concentration and central D2/3 occupancy in older people with Alzheimer's disease by combining: (i) pharmacokinetic data (280 venous samples) from a phase I single (50 mg) dose study in healthy older people (n = 20, 65-79 years); (ii) pharmacokinetic, 18F-fallypride D2/3 receptor imaging and clinical outcome data on patients with Alzheimer's disease who were prescribed amisulpride (25-75 mg daily) to treat psychosis as part of an open study (n = 28; 69-92 years; 41 blood samples, five pretreatment scans, 19 post-treatment scans); and (iii) 18F-fallypride imaging of an antipsychotic free Alzheimer's disease control group (n = 10, 78-92 years), to provide additional pretreatment data...
April 1, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28193454/new-developments-in-brain-research-of-internet-and-gaming-disorder
#18
REVIEW
Aviv Weinstein, Abigail Livny, Abraham Weizman
There is evidence that the neural mechanisms underlying Internet Gaming Disorder (IGD) resemble those of drug addiction. Functional Magnetic Resonance Imaging (fMRI) studies of the resting state and measures of gray matter volume have shown that Internet game playing was associated with changes to brain regions responsible for attention and control, impulse control, motor function, emotional regulation, sensory-motor coordination. Furthermore, Internet game playing was associated with lower white matter density in brain regions that are involved in decision-making, behavioral inhibition and emotional regulation...
April 2017: Neuroscience and Biobehavioral Reviews
https://www.readbyqxmd.com/read/28187335/insight-into-illness-and-its-relationship-to-illness-severity-cognition-and-estimated-antipsychotic-dopamine-receptor-occupancy-in-schizophrenia-an-antipsychotic-dose-reduction-study
#19
Philip Gerretsen, Hiroyoshi Takeuchi, Miracle Ozzoude, Ariel Graff-Guerrero, Hiroyuki Uchida
Little is known about the influence of D2 receptor occupancy on impaired insight into illness (III)-a core feature of schizophrenia. III is associated with illness severity and cognitive dysfunction. Comparably, supratherapeutic D2 receptor occupancy can impair cognition. However, it is unclear how illness severity, cognition, and D2 receptor occupancy interact to influence III in schizophrenia. The aim of this study was to explore the influence of antipsychotic dose reduction on the relationships of illness severity and cognition to III...
May 2017: Psychiatry Research
https://www.readbyqxmd.com/read/28088727/representativeness-of-clinical-pet-study-participants-with-schizophrenia-a-systematic-review
#20
REVIEW
So Kirino, Takefumi Suzuki, Hiroyoshi Takeuchi, Masaru Mimura, Hiroyuki Uchida
While positron emission tomography (PET) studies have provided invaluable data on antipsychotic effects, selection bias remains a serious concern. A systematic review of PET studies that measured dopamine D2 receptor blockade with antipsychotics was conducted to examine their inclusion/exclusion criteria, using PubMed, EMBASE, and ClinicalTrials.gov (last search, September 2016). PET studies were included if they measured D2 receptor occupancy in patients with schizophrenia and included introduction of antipsychotic treatment or antipsychotic regimen change in a systematic manner...
May 2017: Journal of Psychiatric Research
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