Brain glucose metabolism as a neuronal substrate of the abnormal behavioral response to stress in the mdx mouse, a model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is associated with a range of cognitive and behavioral problems. Brain-related comorbidities show clinical heterogeneity depending on the position of the mutation within the multi-promoter dystrophin (DMD) gene, likely due to the differential impact of mutations on the expression of distinct brain dystrophins. A deficiency of the full-length brain dystrophin, Dp427, has been associated with enhanced stress reactivity, characterized by abnormal fear responses in both patients and mdx mouse model.

TSPO-PET in pre-surgical evaluations: Correlation of neuroinflammation and SEEG epileptogenicity mapping in drug-resistant focal epilepsy.

Objectives: Resective surgery in drug-resistant focal epilepsy (DRFE) requires extensive evaluation to localize the epileptogenic zone (EZ). When non-invasive phase 1 assessments (electroencephalography, EEG; magnetic resonance imaging, MRI; and F-Fluorodeoxyglucose-positron emission tomography, [F]FDG-PET) are inconclusive for EZ localization, invasive investigations such as stereo-EEG (SEEG) are necessary. Epileptogenicity maps (Ems) visualize the EZ using SEEG-identified ictal high-frequency oscillations (iHFOs).

Impaired brain glucose metabolism as a biomarker for evaluation of dodecyl creatine ester in creatine transporter deficiency: Insights from patient brain-derived organoids and in vivo [18F]FDG PET imaging in a mouse model.

Creatine transporter deficiency (CTD) is an inborn error of creatine (Cr) metabolism in which Cr is not properly distributed to the brain due to a mutation in the Cr transporter (CrT) SLC6A8 gene. CTD is associated with developmental delays and with neurological disability in children. Dodecyl creatine ester (DCE), as a Cr prodrug, is a promising drug to treat CTD after administration by the nasal route, taking advantage of the nose-to-brain pathway.

[C]Metoclopramide PET can detect a seizure-induced up-regulation of cerebral P-glycoprotein in epilepsy patients.

Background: P-glycoprotein (P-gp) is an efflux transporter which is abundantly expressed at the blood-brain barrier (BBB) and which has been implicated in the pathophysiology of various brain diseases. The radiolabelled antiemetic drug [C]metoclopramide is a P-gp substrate for positron emission tomography (PET) imaging of P-gp function at the BBB. To assess whether [C]metoclopramide can detect increased P-gp function in the human brain, we employed drug-resistant temporal lobe epilepsy (TLE) as a model disease with a well characterised, regional P-gp up-regulation at the BBB.

Brain Glucose Metabolism as a Readout of the Central Nervous System Impact of Cigarette Smoke Exposure and Withdrawal and the Effects of NFL-101, as an Immune-Based Drug Candidate for Smoking Cessation Therapy.

Neuroimaging biomarkers are needed to investigate the impact of smoking withdrawal on brain function. NFL-101 is a denicotinized aqueous extract of tobacco leaves currently investigated as an immune-based smoking cessation therapy in humans. However, the immune response to NFL-101 and its ability to induce significant changes in brain function remain to be demonstrated.

[F]2-fluoro-2-deoxy-sorbitol ([F]FDS) PET imaging repurposed for quantitative estimation of blood-brain barrier permeability in a rat model of Alzheimer's disease.

Numerous studies suggest that blood-brain barrier (BBB) dysfunction may contribute to the progression of Alzheimer's disease (AD). Clinically available neuroimaging methods are needed for quantitative "scoring" of BBB permeability in AD patients. [F]2-fluoro-2-deoxy-sorbitol ([F]FDS), which can be easily obtained from simple chemical reduction of commercial [F]2-fluoro-2-deoxy-glucose ([F]FDG), was investigated as a small-molecule marker of BBB permeability, in a pre-clinical model of AD using in vivo PET imaging.

Non-Invasive Device-Mediated Drug Delivery to the Brain across the Blood-Brain Barrier.

We will be serving as the Guest Editor for this very interesting Special Issue on "Non-Invasive Device-Mediated Drug Delivery to the Brain Across the Blood-Brain Barrier" [...

Imaging quantitative changes in blood-brain barrier permeability using [F]2-fluoro-2-deoxy-sorbitol ([F]FDS) PET in relation to glial cell recruitment in a mouse model of endotoxemia.

The quantitative relationship between the disruption of the blood-brain barrier (BBB) and the recruitment of glial cells was explored in a mouse model of endotoxemia. [F]2-Fluoro-2-deoxy-sorbitol ([F]FDS) PET imaging was used as a paracellular marker for quantitative monitoring of BBB permeability after i.v injection of increasing doses of lipopolysaccharide (LPS) or vehicle (saline, n = 5).

Performance and Sensitivity of [Tc]Tc-sestamibi Compared with Positron Emission Tomography Radiotracers to Measure P-glycoprotein Function in the Kidneys and Liver.

P-glycoprotein (P-gp, encoded in humans by the gene and in rodents by the genes) is a membrane transporter that can restrict the intestinal absorption and tissue distribution of many drugs and may also contribute to renal and hepatobiliary drug excretion. The aim of this study was to compare the performance and sensitivity of currently available radiolabeled P-gp substrates for positron emission tomography (PET) with the single-photon emission computed tomography (SPECT) radiotracer [Tc]Tc-sestamibi for measuring the P-gp function in the kidneys and liver. Wild-type, heterozygous (), and homozygous () knockout mice were used as models of different P-gp abundance in excretory organs.

Brain PET imaging using C-flumazenil and C-buprenorphine does not support the hypothesis of a mutual interaction between buprenorphine and benzodiazepines at the neuroreceptor level.

Among opioids, buprenorphine presents a favorable safety profile with a limited risk of respiratory depression. However, fatalities have been reported when buprenorphine is combined to a benzodiazepine. Potentiation of buprenorphine interaction with opioid receptors (ORs) with benzodiazepines, and/or vice versa, is hypothesized to explain this drug-drug interaction (DDI).

Efficient PD-L1 imaging of murine glioblastoma with FUS-aided immunoPET by leveraging FcRn-antibody interaction.

The passage of antibodies through the blood-brain barrier (BBB) and the blood-tumoral barrier (BTB) is determinant not only to increase the immune checkpoint inhibitors efficacy but also to monitor prognostic and predictive biomarkers such as the programmed death ligand 1 (PD-L1) via immunoPET. Although the involvement of neonatal Fc receptor (FcRn) in antibody distribution has been demonstrated, its function at the BBB remains controversial, while it is unknown at the BTB. In this context, we assessed FcRn's role by pharmacokinetic immunoPET imaging combined with focused ultrasounds (FUS) using unmodified and FcRn low-affinity IgGs targeting PD-L1 in a preclinical orthotopic glioblastoma model.

Dissimilar Effect of P-Glycoprotein and Breast Cancer Resistance Protein Inhibition on the Distribution of Erlotinib to the Retina and Brain in Humans and Mice.

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are two ATP-binding cassette efflux transporters that are coexpressed at the human blood-brain barrier (BBB) and blood-retina barrier (BRB). While pharmacological inhibition of P-gp and/or BCRP results in increased brain distribution of dual P-gp/BCRP substrate drugs, such as the tyrosine kinase inhibitor erlotinib, the effect of P-gp and/or BCRP inhibition on the retinal distribution of such drugs has hardly been investigated. In this study, we used positron emission tomography (PET) imaging to assess the effect of transporter inhibition on the distribution of [C]erlotinib to the human retina and brain.

Parametric Imaging of P-Glycoprotein Function at the Blood-Brain Barrier Using k-maps Generated from [C]Metoclopramide PET Data in Rats, Nonhuman Primates and Humans.

Purpose: PET imaging using [C]metoclopramide revealed the importance of P-glycoprotein (P-gp, ABCB1) in mediating the brain-to-blood efflux of substrates across the blood-brain barrier (BBB). In this work, the elimination rate constant from the brain (k), calculated from dynamic PET images without the need for arterial blood sampling, was evaluated as an outcome parameter for the interpretation of [C]metoclopramide PET data.

Procedures: k parameter was obtained by linear regression of log-transformed brain time-activity curves (TACs).

[F]DPA-714 PET Imaging in the Presurgical Evaluation of Patients With Drug-Resistant Focal Epilepsy.

Background And Objectives: Translocator protein 18 kDa (TSPO) PET imaging is used to monitor glial activation. Recent studies have proposed TSPO PET as a marker of the epileptogenic zone (EZ) in drug-resistant focal epilepsy (DRFE). This study aims to assess the contributions of TSPO imaging using [F]DPA-714 PET and [F]FDG PET for localizing the EZ during presurgical assessment of DRFE, when phase 1 presurgical assessment does not provide enough information.

[C]metoclopramide is a sensitive radiotracer to measure moderate decreases in P-glycoprotein function at the blood-brain barrier.

The efflux transporter P-glycoprotein (P-gp) at the blood-brain barrier limits the cerebral uptake of various xenobiotics. To assess the sensitivity of [C]metoclopramide to measure decreased cerebral P-gp function, we performed [C]metoclopramide PET scans without (baseline) and with partial P-gp inhibition by tariquidar in wild-type, heterozygous and homozygous mice as models with controlled levels of cerebral P-gp expression. Brains were collected to quantify P-gp expression with immunohistochemistry.

Imaging the impact of blood-brain barrier disruption induced by focused ultrasound on P-glycoprotein function.

The P-glycoprotein (P-gp/ABCB1) is a major efflux transporter which impedes the brain delivery of many drugs across the blood-brain barrier (BBB). Focused ultrasound with microbubbles (FUS) enables BBB disruption, which immediate and delayed impact on P-gp function remains unclear. Positron emission tomography (PET) imaging using the radiolabeled substrate [C]metoclopramide provides a sensitive and translational method to study P-gp function at the living BBB.

Carbon Dioxide Radical Anion by Photoinduced Equilibration between Formate Salts and [C, C, C]CO: Application to Carbon Isotope Radiolabeling.

The need for carbon-labeled radiotracers is increasingly higher in drug discovery and development (carbon-14, β, = 5730 years) as well as in positron emission tomography (PET) for in vivo molecular imaging applications (carbon-11, β, = 20.4 min). However, the structural diversity of radiotracers is still systematically driven by the narrow available labeled sources and methodologies.

Validation of a pharmacological imaging challenge using C-buprenorphine and F-2-fluoro-2-deoxy-D-glucose positron emission tomography to study the effects of buprenorphine to the rat brain.

Aim: Buprenorphine mainly acts as an agonist of mu-opioid receptors (mu-OR). High dose buprenorphine does not cause respiratory depression and can be safely administered to elicit typical opioid effects and explore pharmacodynamics. Acute buprenorphine, associated with functional and quantitative neuroimaging, may therefore provide a fully translational pharmacological challenge to explore the variability of response to opioids .

Influence of P-glycoprotein on pulmonary disposition of the model substrate [C]metoclopramide assessed by PET imaging in rats.

In the lungs, the membrane transporter P-glycoprotein (P-gp) is expressed in the apical (i.e. lumen-facing) membrane of airway epithelial cells and in the luminal (blood-facing) membrane of pulmonary capillary endothelial cells.

Impact of Cytochrome Induction or Inhibition on the Plasma and Brain Kinetics of [C]metoclopramide, a PET Probe for P-Glycoprotein Function at the Blood-Brain Barrier.

[11C]metoclopramide PET imaging provides a sensitive and translational tool to explore P-glycoprotein (P-gp) function at the blood-brain barrier (BBB). Patients with neurological diseases are often treated with cytochrome (CYP) modulators which may impact the plasma and brain kinetics of [11C]metoclopramide. The impact of the CYP inducer carbamazepine or the CYP inhibitor ritonavir on the brain and plasma kinetics of [11C]metoclopramide was investigated in rats.