-
Journal of Nuclear Medicine : Official... Apr 2022Digital autoradiography (DAR) is a powerful tool to quantitatively determine the distribution of a radiopharmaceutical within a tissue section and is widely used in drug...
Digital autoradiography (DAR) is a powerful tool to quantitatively determine the distribution of a radiopharmaceutical within a tissue section and is widely used in drug discovery and development. However, the low image resolution and significant background noise can result in poor correlation, even errors, between radiotracer distribution, anatomic structure, and molecular expression profiles. Differing from conventional optical systems, the point-spread function in DAR is determined by properties of radioisotope decay, phosphor, and digitizer. Calibration of an experimental point-spread function a priori is difficult, prone to error, and impractical. We have developed a content-adaptive restoration algorithm to address these problems. We model the DAR imaging process using a mixed Poisson-gaussian model and blindly restore the image by a penalized maximum-likelihood expectation-maximization algorithm (PG-PEM). PG-PEM implements a patch-based estimation algorithm with density-based spatial clustering of applications with noise to estimate noise parameters and uses L2 and Hessian Frebonius norms as regularization functions to improve performance. First, PG-PEM outperformed other restoration algorithms at the denoising task ( 0.01). Next, we implemented PG-PEM on preclinical DAR images (F-FDG, treated mouse tumor and heart; F-NaF, treated mouse femur) and clinical DAR images (bone biopsy sections from RaCl-treated castration-resistant prostate cancer patients). DAR images restored by PG-PEM of all samples achieved a significantly higher effective resolution and contrast-to-noise ratio and a lower SD of background ( 0.0001). Additionally, by comparing the registration results between the clinical DAR images and the segmented bone masks from the corresponding histologic images, we found that the radiopharmaceutical distribution was significantly improved ( 0.0001). PG-PEM is able to increase resolution and contrast while robustly accounting for DAR noise and demonstrates the capacity to be widely implemented to improve preclinical and clinical DAR imaging of radiopharmaceutical distribution.
Topics: Algorithms; Animals; Autoradiography; Diagnostic Imaging; Fluorodeoxyglucose F18; Humans; Image Processing, Computer-Assisted; Male; Mice; Phantoms, Imaging; Radiopharmaceuticals; Tissue Distribution
PubMed: 34385337
DOI: 10.2967/jnumed.121.262270 -
European Journal of Pharmaceutical... Feb 2021With the ambition of improving the management of pancreatic neuroendocrine tumors (P-NETs), we developed and preliminary validated a novel fluorine-18 labelled HSP...
PURPOSE
With the ambition of improving the management of pancreatic neuroendocrine tumors (P-NETs), we developed and preliminary validated a novel fluorine-18 labelled HSP ligand.
METHODS
A precursor containing methoxymethyl ethers protecting groups and a tosyl as leaving group was synthesized. The target compound was labeled with nucleophilic F-fluoride and the protecting groups was subsequently removed with hydrochloric acid before purification. In vitro cell- and frozen section autoradiography and in vivo animal studies were performed.
RESULTS
The precursor was successfully synthesized and utilized in the F-radiolabeling giving 0.5-1.0 GBq of pure product with a synthesis time of 70 min. In vitro experiments indicated a high specific binding, but in vivo studies showed no tumor uptake due to fast hepatobiliary metabolism and excretion.
CONCLUSIONS
Despite the unfavorable in vivo properties of the tracer, the promising results from in vitro autoradiography experiments in frozen sections of P-NETs from surgical resection encourage us to continue the project aiming the improvement of in vivo properties of the tracer.
Topics: Animals; Autoradiography; Fluorides; Fluorine Radioisotopes; Ligands; Positron-Emission Tomography; Radiopharmaceuticals
PubMed: 33221456
DOI: 10.1016/j.ejps.2020.105647 -
Biomedicines Mar 2023High-resolution scans of immunohistochemical (IHC) stains of Alzheimer's disease (AD) brain slices and radioligand autoradiography both provide information about the...
Measurement of Aβ Amyloid Plaques and Tau Protein in Postmortem Human Alzheimer's Disease Brain by Autoradiography Using [F]Flotaza, [I]IBETA, [I]IPPI and Immunohistochemistry Analysis Using QuPath.
High-resolution scans of immunohistochemical (IHC) stains of Alzheimer's disease (AD) brain slices and radioligand autoradiography both provide information about the distribution of Aβ plaques and Tau, the two common proteinopathies in AD. Accurate assessment of the amount and regional location of Aβ plaques and Tau is essential to understand the progression of AD pathology. Our goal was to develop a quantitative method for the analysis of IHC-autoradiography images. Postmortem anterior cingulate (AC) and corpus callosum (CC) from AD and control (CN) subjects were IHC stained with anti-Aβ for Aβ plaques and autoradiography with [F]flotaza and [I]IBETA for Aβ plaques. For Tau, [I]IPPI, a new radiotracer, was synthesized and evaluated in the AD brain. For Tau imaging, brain slices were IHC stained with anti-Tau and autoradiography using [I]IPPI and [I]IPPI. Annotations for Aβ plaques and Tau using QuPath for training and pixel classifiers were generated to measure the percent of the area of Aβ plaques and Tau in each slice. The binding of [I]IPPI was observed in all AD brains with an AC/CC ratio > 10. Selectivity to Tau was shown by blocking [I]IPPI with MK-6240. Percent positivity for Aβ plaques was 4-15%, and for Tau, it was 1.3 to 35%. All IHC Aβ plaque-positive subjects showed [F]flotaza and [I]IBETA binding with a positive linear correlation (r > 0.45). Tau-positive subjects showed [I]IPPI binding with a stronger positive linear correlation (r > 0.80). This quantitative IHC-autoradiography approach provides an accurate measurement of Aβ plaques and Tau within and across subjects.
PubMed: 37189652
DOI: 10.3390/biomedicines11041033 -
Methods in Molecular Biology (Clifton,... 2023Autoradiography of radiolabeled GTPγS ([S]GTPγS) binding is a relevant technique to study the function of G protein-coupled receptors (GPCRs) ex vivo. Here, we...
Autoradiography of radiolabeled GTPγS ([S]GTPγS) binding is a relevant technique to study the function of G protein-coupled receptors (GPCRs) ex vivo. Here, we describe the protocol for such a method, suitable for investigating CB receptor functionality in tissue slices from rodent brains.
Topics: Autoradiography; Brain; Guanosine 5'-O-(3-Thiotriphosphate); Receptors, G-Protein-Coupled; Sulfur Radioisotopes
PubMed: 36152186
DOI: 10.1007/978-1-0716-2728-0_14 -
ACS Chemical Neuroscience Feb 2022The homo-pentameric alpha 7 receptor is one of the major types of neuronal nicotinic acetylcholine receptors (α7-nAChRs) related to cognition, memory formation, and...
The homo-pentameric alpha 7 receptor is one of the major types of neuronal nicotinic acetylcholine receptors (α7-nAChRs) related to cognition, memory formation, and attention processing. The mapping of α7-nAChRs by PET pulls a lot of attention to realize the mechanism and development of CNS diseases such as AD, PD, and schizophrenia. Several PET radioligands have been explored for the detection of the α7-nAChR. F-ASEM is the most functional for quantification of α7-nAChRs in the human brain. The first aim of this study was to initially use results from in silico and machine learning techniques to prescreen and predict the binding energy and other properties of ASEM analogues and to interpret these properties in terms of atomic structures using F-ASEM as a lead structure, and second, to label some selected candidates with carbon-11/hydrogen-3 (C/H) and to evaluate the binding properties and using the labeled candidates. In silico predictions are obtained from perturbation free-energy calculations preceded by molecular docking, molecular dynamics, and metadynamics simulations. Machine learning techniques have been applied for the BBB and P-gp-binding properties. Six analogues of ASEM were labeled with C, and three of them were additionally labeled with H. Binding properties were further evaluated using autoradiography (ARG) and PET measurements in non-human primates (NHPs). Radiometabolites were measured in NHP plasma. All six compounds were successfully synthesized. Evaluation with ARG showed that C-Kln83 was preferably binding to the α7-nAChR. Competition studies showed that 80% of the total binding was displaced. Further ARG studies using H-KIn-83 replicated the preliminary results. In the NHP PET study, the distribution pattern of C-KIn-83 was similar to other α7 nAChR PET tracers. The brain uptake was relatively low and increased by the administration of tariquidar, indicating a substrate of P-gp. The ASEM blocking study showed that C-KIn-83 specifically binds to α7 nAChRs. Preliminary evaluation of KIn-83 by ARG with both C and H and evaluation in NHP showed favorable properties for selectively imaging α7-nAChRs, despite a relatively low brain uptake.
Topics: Animals; Azabicyclo Compounds; Cyclic S-Oxides; Molecular Docking Simulation; Positron-Emission Tomography; Receptors, Nicotinic; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 35020351
DOI: 10.1021/acschemneuro.1c00730 -
Cancers Apr 2023The imaging of Prostate-Specific Membrane Antigen (PSMA) is now widely used at the initial staging of prostate cancers in patients with a high metastatic risk. However,...
UNLABELLED
The imaging of Prostate-Specific Membrane Antigen (PSMA) is now widely used at the initial staging of prostate cancers in patients with a high metastatic risk. However, its ability to detect low-grade tumor lesions is not optimal.
METHODS
First, we prospectively performed neurotensin receptor-1 (NTS) IHC in a series of patients receiving both [Ga]Ga-PSMA-617 and [Ga]Ga-RM2 before prostatectomy. In this series, PSMA and GRP-R IHC were also available (n = 16). Next, we aimed at confirming the PSMA/GRP-R/NTS expression profile by retrospective autoradiography (n = 46) using a specific radiopharmaceuticals study and also aimed to decipher the expression of less-investigated targets such as NTS, SST and CXCR4.
RESULTS
In the IHC study, all samples with negative PSMA staining (two patients with ISUP 2 and one with ISUP 3) were strongly positive for NTS staining. No samples were negative for all three stains-for PSMA, GRP-R or NTS. In the autoradiography study, binding of [In]In-PSMA-617 was high in all ISUP groups. However, some samples did not bind or bound weakly to [In]In-PSMA-617 (9%). In these cases, binding of [n]In-JMV 6659 and [In]In-JMV 7488 towards NTS and NTS was high.
CONCLUSIONS
Targeting PSMA and NTS/NTS could allow for the detection of all intraprostatic lesions.
PubMed: 37190273
DOI: 10.3390/cancers15082345 -
ACS Infectious Diseases Dec 2019Bedaquiline is a promising drug against tuberculosis (TB), but limited data are available on its intralesional pharmacokinetics. Moreover, current techniques rely on...
Bedaquiline is a promising drug against tuberculosis (TB), but limited data are available on its intralesional pharmacokinetics. Moreover, current techniques rely on invasive tissue resection, which is difficult in humans and generally limited even in animals. In this study, we developed a novel radiosynthesis for Br-bedaquiline and performed noninvasive, longitudinal whole-body positron emission tomography (PET) in live, -infected mice over 48 h. After the intravenous injection, Br-bedaquiline distributed to all organs and selectively localized to adipose tissue and liver, with excellent penetration into infected lung lesions (86%) and measurable penetration into the brain parenchyma (15%). Ex vivo high resolution, two-dimensional autoradiography, and same section hematoxylin/eosin and immunofluorescence provided detailed intralesional drug biodistribution. PET bioimaging and high-resolution autoradiography are novel techniques that can provide detailed, multicompartment, and intralesional pharmacokinetics of new and existing TB drugs. These technologies can significantly advance efforts to optimize drug dosing.
Topics: Administration, Intravenous; Animals; Autoradiography; Diarylquinolines; Disease Models, Animal; Female; Humans; Lung; Mice; Positron-Emission Tomography; Tuberculosis; Whole Body Imaging
PubMed: 31345032
DOI: 10.1021/acsinfecdis.9b00207 -
Cold Spring Harbor Protocols Dec 2020Bands of radioactive DNA separated by polyacrylamide gel electrophoresis may be detected by autoradiography or phosphorimaging. Analytical polyacrylamide gels containing...
Bands of radioactive DNA separated by polyacrylamide gel electrophoresis may be detected by autoradiography or phosphorimaging. Analytical polyacrylamide gels containing radioactive DNA are usually fixed and dried before autoradiography. However, if bands of radioactive DNA are to be recovered from the gel, the gel should generally not be fixed or dried.
Topics: Acrylic Resins; Autoradiography; DNA; Electrophoresis, Polyacrylamide Gel; Isotope Labeling; Radiographic Image Enhancement; Radioisotopes; X-Ray Film
PubMed: 33262237
DOI: 10.1101/pdb.prot100420 -
Journal of Neuropathology and... Sep 2019The sudden infant death syndrome (SIDS) is the leading cause of postneonatal infant mortality in the United States today, with an overall rate of 0.39/1000 live births.... (Review)
Review
The sudden infant death syndrome (SIDS) is the leading cause of postneonatal infant mortality in the United States today, with an overall rate of 0.39/1000 live births. It is defined as the sudden and unexpected death of an infant <12 months of age that remains unexplained after a complete autopsy, death scene investigation, and review of the clinical history. The serotonin brainstem hypothesis has been a leading hypothesis for SIDS over the last 2 decades. Our laboratory has studied this hypothesis over time with a variety of tissue techniques, including tissue receptor autoradiography, high performance liquid chromatography, Western blot analysis, immunocytochemistry, and proteomics. The purpose of this article is to review the progress in our laboratory toward supporting this hypothesis. We conclude that an important subset of SIDS infants has serotonergic abnormalities resulting from a "core lesion" in the medullary reticular formation comprised of nuclei that contain serotonin neurons. This lesion could lead to a failure of protective brainstem responses to homeostatic challenges during sleep in a critical developmental period which cause sleep-related sudden death.
Topics: Brain Stem; Humans; Infant; Infant, Newborn; Midbrain Reticular Formation; Serotonergic Neurons; Serotonin; Sudden Infant Death
PubMed: 31397480
DOI: 10.1093/jnen/nlz062 -
Journal of Alzheimer's Disease : JAD 2024Although sporadic Alzheimer's disease (AD) is a neurodegenerative disorder of unknown etiology, familial AD is associated with specific gene mutations. A commonality...
BACKGROUND
Although sporadic Alzheimer's disease (AD) is a neurodegenerative disorder of unknown etiology, familial AD is associated with specific gene mutations. A commonality between these forms of AD is that both display multiple pathogenic events including cholinergic and lipid dysregulation.
OBJECTIVE
We aimed to identify the relevant lipids and the activity of their related receptors in the frontal cortex and correlating them with cognition during the progression of AD.
METHODS
MALDI-mass spectrometry imaging (MSI) and functional autoradiography was used to evaluate the distribution of phospholipids/sphingolipids and the activity of cannabinoid 1 (CB1), sphingosine 1-phosphate 1 (S1P1), and muscarinic M2/M4 receptors in the frontal cortex (FC) of people that come to autopsy with premortem clinical diagnosis of AD, mild cognitive impairment (MCI), and no cognitive impairment (NCI).
RESULTS
MALDI-MSI revealed an increase in myelin-related lipids, such as diacylglycerol (DG) 36:1, DG 38:5, and phosphatidic acid (PA) 40:6 in the white matter (WM) in MCI compared to NCI, and a downregulation of WM phosphatidylinositol (PI) 38:4 and PI 38:5 levels in AD compared to NCI. Elevated levels of phosphatidylcholine (PC) 32:1, PC 34:0, and sphingomyelin 38:1 were observed in discrete lipid accumulations in the FC supragranular layers during disease progression. Muscarinic M2/M4 receptor activation in layers V-VI decreased in AD compared to MCI. CB1 receptor activity was upregulated in layers V-VI, while S1P1 was downregulated within WM in AD relative to NCI.
CONCLUSIONS
FC WM lipidomic alterations are associated with myelin dyshomeostasis in prodromal AD, suggesting WM lipid maintenance as a potential therapeutic target for dementia.
Topics: Humans; Alzheimer Disease; Cognitive Dysfunction; Receptor, Muscarinic M4; Frontal Lobe; Cholinergic Agents; Lipids
PubMed: 38578893
DOI: 10.3233/JAD-231485