Publications by authors named "Nabulsi N"

Aim: Inadequate response to antidepressant therapy (ADT) is common in major depressive disorder (MDD); atypical antipsychotic (AA) adjunctive therapy may be effective for these patients. This study aimed to compare healthcare resource utilization (HRU) and costs between patients initiating the AA cariprazine as their first adjunctive therapy vs those initiating cariprazine subsequently.

Methods: The Merative MarketScan® Commercial Database (January 1, 2015, to June 30, 2021) was used to identify US adults with MDD and ≥1 pharmacy claim for cariprazine adjunctive to ADT in 2018 or after.

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[F]FE-PE2I PET is a promising alternative to single positron emission computed tomography-based dopamine transporter (DAT) imaging in Parkinson's disease. While the excellent discriminative power of [F]FE-PE2I PET has been established, so far only one study has reported meaningful associations between motor severity scores and DAT availability. In this study, we use high-resolution (∼3 mm isotropic) PET to provide an independent validation for the clinical correlates of [F]FE-PE2I imaging in separate cross-sectional (28 participants with Parkinson's disease, Hoehn-Yahr: 2 and 14 healthy individuals) and longitudinal (initial results from 6 participants with Parkinson's disease with 2-year follow-up) cohorts.

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  • The study explores the effects of calcitriol (active vitamin D) on dopamine receptors in healthy adults, utilizing a randomized, double-blind design with PET scans before and after amphetamine administration.
  • Findings indicate that calcitriol enhances dopamine receptor availability in certain brain regions (ventral striatum and dorsal putamen) and influences dopamine release after amphetamine.
  • These results suggest a potential role for vitamin D in targeting dopaminergic function, which may be relevant for treating disorders with dopamine dysregulation.
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  • The study investigates the relationship between metabotropic glutamate receptor subtype 5 (mGluR5) and synaptic density in early Alzheimer's disease (AD) using PET imaging techniques.
  • Findings reveal a strong positive correlation between mGluR5 levels and synaptic density in the hippocampus and entorhinal cortex of Alzheimer’s patients, but less significant in cognitively normal individuals.
  • The research concludes that loss of mGluR5 in the medial temporal lobe is linked to synaptic loss, suggesting its potential role in AD pathology.
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  • The study investigates synaptic density in autistic adults using positron emission tomography (PET) and synaptic vesicle glycoprotein 2A (SV2A) as a marker.
  • Results show that autistic individuals exhibit a 17% lower synaptic density across the whole cortex compared to non-autistic peers, with significant deficits in various brain regions, especially the prefrontal cortex.
  • The findings suggest that lower synaptic density is associated with increased autistic features, pointing to a potential molecular basis for autism that requires further exploration.
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Simplified methods of acquisition and quantification would facilitate the use of synaptic density imaging in multicenter and longitudinal studies of Alzheimer disease (AD). We validated a simplified tissue-to-reference ratio method using SUV ratios (SUVRs) for estimating synaptic density with [C]UCB-J PET. Participants included 31 older adults with AD and 16 with normal cognition.

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Dynamic brain immune function in individuals with posttraumatic stress disorder is rarely studied, despite evidence of peripheral immune dysfunction. Positron emission tomography brain imaging using the radiotracer [C]PBR28 was used to measure the 18-kDa translocator protein (TSPO), a microglial marker, at baseline and 3 h after administration of lipopolysaccharide (LPS), a potent immune activator. Data were acquired in 15 individuals with PTSD and 15 age-matched controls.

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Purpose: [F]SynVesT-1, a positron emission tomography (PET) radiotracer for the synaptic vesicle glycoprotein 2A (SV2A), demonstrates kinetics similar to [C]UCB-J, with high brain uptake, fast kinetics fitting well with the one-tissue compartment (1TC) model, and excellent test-retest reproducibility. Challenges arise due to the similarity between k and [Formula: see text] (efflux rate of the reference region), when applying the simplified reference tissue model (SRTM) and related methods in [C]UCB-J studies to accurately estimate [Formula: see text]. This study evaluated the suitability of these methods to estimate [F]SynVesT-1 binding using centrum semiovale (CS) or cerebellum (CER) as reference regions.

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Introduction: Major depressive disorder (MDD) is a debilitating and costly condition. This analysis characterized the health-related quality of life (HRQoL), health care resource utilization (HCRU), and costs between patients with versus without MDD, and across MDD severity levels.

Methods: The 2019 National Health and Wellness Survey was used to identify adults with MDD, who were stratified by disease severity (minimal/mild, moderate, moderately severe, severe), and those without MDD.

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Parkinson's disease (PD) is the fastest growing neurodegenerative disease, but at present there is no cure, nor any disease-modifying treatments. Synaptic biomarkers from in vivo imaging have shown promise in imaging loss of synapses in PD and other neurodegenerative disorders. Here, we provide new clinical insights from a cross-sectional, high-resolution positron emission tomography (PET) study of 30 PD individuals and 30 age- and sex-matched healthy controls (HC) with the radiotracer [C]UCB-J, which binds to synaptic vesicle glycoprotein 2A (SV2A), and is therefore, a biomarker of synaptic density in the living brain.

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Article Synopsis
  • PET imaging using F-SynVesT-2 allows for the noninvasive measurement of synaptic vesicle glycoprotein 2A, providing insight into synapse quantification in the brain.
  • The study involved nine healthy participants and assessed the ligand's brain kinetics, test-retest reliability, and specific binding through various imaging techniques and models.
  • Findings indicated that F-SynVesT-2 has rapid brain entry, reliable quantification using a one-tissue compartment model, and low test-retest variability, making it a promising tool for future synaptic research.
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Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons. Exercise has been reported to slow the clinical progression of PD. We evaluated the dopaminergic system of patients with mild and early PD before and after a six-month program of intense exercise.

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Background: Stress is a potent activator of the hypothalamic-pituitary-adrenal (HPA) axis, initiating the release of glucocorticoid hormones, such as cortisol. Alcohol consumption can lead to HPA axis dysfunction, including altered cortisol levels. Until recently, research has only been able to examine peripheral cortisol associated with alcohol use disorder (AUD) in humans.

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Purpose: Aging is a major societal concern due to age-related functional losses. Synapses are crucial components of neural circuits, and synaptic density could be a sensitive biomarker to evaluate brain function. [C]UCB-J is a positron emission tomography (PET) ligand targeting synaptic vesicle glycoprotein 2A (SV2A), which can be used to evaluate brain synaptic density in vivo.

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  • Advances in treatment for hematologic malignancies (HM) have improved life expectancy, leading to a need for better long-term cancer pain management, as explored in a study on opioid use.
  • The study analyzed data from 43,190 adults diagnosed with HM between 2013 and 2019, focusing on high-risk opioid use and associated issues like opioid use disorder and hospital visits.
  • Results showed that 20% of patients had high-risk opioid use, which greatly increased the likelihood of developing opioid use disorder or requiring emergency care, underscoring the need for careful monitoring of pain management in HM patients.
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Objective: Multimodal imaging techniques have furthered our understanding of how different aspects of Alzheimer's disease (AD) pathology relate to one another. Diffusion tensor imaging (DTI) measures such as mean diffusivity (MD) may be a surrogate measure of the changes in gray matter structure associated with AD. Positron emission tomography (PET) imaging of synaptic vesicle glycoprotein 2A (SV2A) has been used to quantify synaptic loss, which is the major pathological correlate of cognitive impairment in AD.

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For some positron emission tomography studies, radiotracer is administered as bolus plus continuous infusion (B/I) to achieve a state of equilibrium. This approach can reduce scanning time and simplify data analysis; however, the method must be validated and optimized for each tracer. This study aimed to validate a B/I method for quantification of synaptic density using radiotracers which target the synaptic vesicle glycoprotein 2 A: [C]UCB-J and [F]SynVesT-1.

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In humans, the negative effects of alcohol are linked to immune dysfunction in both the periphery and the brain. Yet acute effects of alcohol on the neuroimmune system and its relationships with peripheral immune function are not fully understood. To address this gap, immune response to an alcohol challenge was measured with positron emission tomography (PET) using the radiotracer [C]PBR28, which targets the 18-kDa translocator protein, a marker sensitive to immune challenges.

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Background: Synaptic loss is considered an early pathological event and major structural correlate of cognitive impairment in Alzheimer's disease (AD). We used principal component analysis (PCA) to identify regional patterns of covariance in synaptic density using [C]UCB-J PET and assessed the association between principal components (PC) subject scores with cognitive performance.

Methods: [C]UCB-J binding was measured in 45 amyloid + participants with AD and 19 amyloid- cognitively normal participants aged 55-85.

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Purpose: Opioids are essential for treating pain in hematologic malignancies (HM), yet are heavily stigmatized in the era of the opioid epidemic. Stigma and negative attitudes towards opioids may contribute to poorly managed cancer pain. We aimed to understand patient attitudes towards opioids for HM pain management, particularly among historically marginalized populations.

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Purpose: Currently, there are multiple active clinical trials involving poly(ADP-ribose) polymerase (PARP) inhibitors in the treatment of glioblastoma. The noninvasive quantification of baseline PARP expression using positron emission tomography (PET) may provide prognostic information and lead to more precise treatment. Due to the lack of brain-penetrant PARP imaging agents, the reliable and accurate in vivo quantification of PARP in the brain remains elusive.

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PF-05212377 (SAM760) is a potent and selective 5-HT antagonist, previously under development for the treatment of Alzheimer's disease. In vitro, PF-05212377 was determined to be a P-gp/non-BCRP human transporter substrate. Species differences were observed in the in vivo brain penetration of PF-05212377 with a ratio of the unbound concentration in brain/unbound concentration in plasma (C /C ) of 0.

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Background: Understanding the neurobiology underlying bipolar disorder (BD) versus major depressive disorder (MDD) is crucial for accurate diagnosis and for driving the discovery of novel treatments. A promising target is the metabotropic glutamate receptor 5 (mGluR5), a modulator of glutamate transmission associated with synaptic plasticity. We measured mGluR5 availability in individuals with MDD and BD for the first time using positron emission tomography.

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