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Methods in Molecular Biology (Clifton,... 2022Positron emission tomography (PET) is a quantitative imaging technique that uses molecules labeled with positron-emitting radionuclides to visualize and measure...
Positron emission tomography (PET) is a quantitative imaging technique that uses molecules labeled with positron-emitting radionuclides to visualize and measure biochemical processes in the tissues of living subjects. In recent years, different PET tracers have been evaluated for their ability to characterize the atherosclerotic process in order to study the activity of the disease. Here, we describe detailed PET methods for preclinical studies of atherosclerosis and summarize the key methodological aspects of PET imaging in clinical studies of atherosclerosis.
Topics: Atherosclerosis; Fluorodeoxyglucose F18; Humans; Positron-Emission Tomography; Radioisotopes; Radiopharmaceuticals
PubMed: 35238004
DOI: 10.1007/978-1-0716-1924-7_50 -
Pharmaceuticals (Basel, Switzerland) Dec 2020Understanding pharmacokinetics and biodistribution of antibody-drug conjugates (ADCs) is a one of the critical steps enabling their successful development and... (Review)
Review
Understanding pharmacokinetics and biodistribution of antibody-drug conjugates (ADCs) is a one of the critical steps enabling their successful development and optimization. Their complex structure combining large and small molecule characteristics brought out multiple bioanalytical methods to decipher the behavior and fate of both components in vivo. In this respect, these methods must provide insights into different key elements including half-life and blood stability of the construct, premature release of the drug, whole-body biodistribution, and amount of the drug accumulated within the targeted pathological tissues, all of them being directly related to efficacy and safety of the ADC. In this review, we will focus on the main strategies enabling to quantify and characterize ADCs in biological matrices and discuss their associated technical challenges and current limitations.
PubMed: 33327644
DOI: 10.3390/ph13120462 -
Biomedicines Sep 2022Pharmacokinetic assessment of drug disposition processes in vivo is critical in predicting pharmacodynamics and toxicology to reduce the risk of inappropriate drug... (Review)
Review
Pharmacokinetic assessment of drug disposition processes in vivo is critical in predicting pharmacodynamics and toxicology to reduce the risk of inappropriate drug development. The blood-brain barrier (BBB), a special physiological structure in brain tissue, hinders the entry of targeted drugs into the central nervous system (CNS), making the drug concentrations in target tissue correlate poorly with the blood drug concentrations. Additionally, once non-CNS drugs act directly on the fragile and important brain tissue, they may produce extra-therapeutic effects that may impair CNS function. Thus, an intracerebral pharmacokinetic study was developed to reflect the disposition and course of action of drugs following intracerebral absorption. Through an increasing understanding of the fine structure in the brain and the rapid development of analytical techniques, cerebral pharmacokinetic techniques have developed into non-invasive imaging techniques. Through non-invasive imaging techniques, molecules can be tracked and visualized in the entire BBB, visualizing how they enter the BBB, allowing quantitative tools to be combined with the imaging system to derive reliable pharmacokinetic profiles. The advent of imaging-based pharmacokinetic techniques in the brain has made the field of intracerebral pharmacokinetics more complete and reliable, paving the way for elucidating the dynamics of drug action in the brain and predicting its course. The paper reviews the development and application of imaging technologies for cerebral pharmacokinetic study, represented by optical imaging, radiographic autoradiography, radionuclide imaging and mass spectrometry imaging, and objectively evaluates the advantages and limitations of these methods for predicting the pharmacodynamic and toxic effects of drugs in brain tissues.
PubMed: 36289709
DOI: 10.3390/biomedicines10102447 -
Nuclear Medicine and Biology 2020Molecular radiotherapy exploiting short-range Auger electron-emitting radionuclides has potential for targeted cancer treatment and, in particular, is an attractive...
INTRODUCTION
Molecular radiotherapy exploiting short-range Auger electron-emitting radionuclides has potential for targeted cancer treatment and, in particular, is an attractive option for managing micrometastatic disease. Here, an approach using chelator-trastuzumab conjugates to target radioactivity to breast cancer cells was evaluated as a proof-of-concept to assess the suitability of Ga as a therapeutic radionuclide.
METHODS
THP-trastuzumab and DOTA-trastuzumab were synthesised and radiolabelled with Auger electron-emitters Ga and In, respectively. Radiopharmaceuticals were tested for HER2-specific binding and internalisation, and their effects on viability (dye exclusion) and clonogenicity of HER2-positive HCC1954 and HER2-negative MDA-MB-231 cell lines was measured. Labelled cell populations were studied by microautoradiography.
RESULTS
Labelling efficiencies for [Ga]Ga-THP-trastuzumab and [In]In-DOTA-trastuzumab were 90% and 98%, respectively, giving specific activities 0.52 ± 0.16 and 0.61 ± 0.11 MBq/μg (78-92 GBq/μmol). At 4 nM total antibody concentration and 200 × 10 cells/mL, [Ga]Ga-THP-trastuzumab showed higher percentage of cell association (10.7 ± 1.3%) than [In]In-DOTA-trastuzumab (6.2 ± 1.6%; p = 0.01). The proportion of bound activity that was internalised did not differ significantly for the two tracers (62.1 ± 1.4% and 60.8 ± 15.5%, respectively). At 100 nM, percentage cell binding of both radiopharmaceuticals was greatly reduced compared to 4 nM and did not differ significantly between the two (1.2 ± 1.0% [Ga]Ga-THP-trastuzumab and 0.8 ± 0.9% for [In]In-DOTA-trastuzumab). Viability and clonogenicity of HER2-positive cells decreased when each radionuclide was incorporated into cells by conjugation with trastuzumab, but not when the same level of radioactivity was confined to the medium by omitting the antibody conjugation, suggesting that Ga needs to be cell-bound or internalised for a therapeutic effect. Microautoradiography showed that radioactivity bound to individual cells varied considerably within the population.
CONCLUSIONS
[Ga]Ga-THP-trastuzumab reduced cell viability and clonogenicity only when cell-bound, suggesting Ga holds promise as a therapeutic radionuclide as part of a targeted radiopharmaceutical. The causes and consequences of non-homogeneous uptake among the cell population should be explored.
Topics: Autoradiography; Cell Line, Tumor; Cell Survival; Electrons; Gallium Radioisotopes; Humans; Isotope Labeling; Trastuzumab
PubMed: 31889612
DOI: 10.1016/j.nucmedbio.2019.12.004 -
Scientific Reports Dec 2021Biomarkers for the measurement of islets of Langerhans could help elucidate the etiology of diabetes. Synaptic vesicle glycoprotein 2 A (SV2A) is a potential marker...
Biomarkers for the measurement of islets of Langerhans could help elucidate the etiology of diabetes. Synaptic vesicle glycoprotein 2 A (SV2A) is a potential marker reported to be localized in the endocrine pancreas. [C]UCB-J is a novel positron emission tomography (PET) radiotracer that binds to SV2A and was previously evaluated as a synaptic marker in the central nervous system. Here, we evaluated whether [C]UCB-J could be utilized as a PET tracer for the islets of Langerhans in the pancreas by targeting SV2A. The mRNA transcription of SV2A was evaluated in human isolated islets of Langerhans and exocrine tissue. In vitro autoradiography was performed on pancreas and brain sections from rats and pigs, and consecutive sections were immunostained for insulin. Sprague-Dawley rats were examined with PET-MRI and ex vivo autoradiography at baseline and with administration of levetiracetam (LEV). Similarly, pigs were examined with dynamic PET-CT over the pancreas and brain after administration of [C]UCB-J at baseline and after pretreatment with LEV. In vivo radioligand binding was assessed using a one-compartment tissue model. The mRNA expression of SV2A was nearly 7 times higher in endocrine tissue than in exocrine tissue (p < 0.01). In vitro autoradiography displayed focal binding of [C]UCB-J in the pancreas of rats and pigs, but the binding pattern did not overlap with the insulin-positive areas or with ex vivo autoradiography. In rats, pancreas binding was higher than that in negative control tissues but could not be blocked by LEV. In pigs, the pancreas and brain exhibited accumulation of [C]UCB-J above the negative control tissue spleen. While brain binding could be blocked by pretreatment with LEV, a similar effect was not observed in the pancreas. Transcription data indicate SV2A to be a valid target for imaging islets of Langerhans, but [C]UCB-J does not appear to have sufficient sensitivity for this application.
Topics: Animals; Female; Islets of Langerhans; Male; Membrane Glycoproteins; Nerve Tissue Proteins; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Pyridines; Pyrrolidinones; Radiopharmaceuticals; Rats, Sprague-Dawley; Swine; Rats
PubMed: 34963683
DOI: 10.1038/s41598-021-04188-6 -
Diagnostics (Basel, Switzerland) Apr 2021The study aims to assess site assessment of the performance of F-PBR-111 as a neuroinflammation marker in the cuprizone mouse model of multiple sclerosis (MS). F-PBR-111...
The study aims to assess site assessment of the performance of F-PBR-111 as a neuroinflammation marker in the cuprizone mouse model of multiple sclerosis (MS). F-PBR-111 PET imaging has not been well evaluated in multiple sclerosis applications both in preclinical and clinical research. This study will help establish the potential utility of F-PBR-111 PET in preclinical MS research and future animal and future human applications. F-PBR-111 PET/CT was conducted at 3.5 weeks ( = 7) and 5.0 weeks ( = 7) after cuprizone treatment or sham control ( = 3) in the mouse model. A subgroup of mice underwent autoradiography with cryosectioned brain tissue. T2 weighted MRI was performed to obtain the brain structural data of each mouse. F-PBR-111 uptake was assessed in multiple brain regions with PET and autoradiography images. The correlation between autoradiography and immunofluorescence staining of neuroinflammation (F4/80 and CD11b) was measured. Compared to control mice, significant F-PBR-111 uptake in the corpus callosum ( < 0.001), striatum (caudate and internal capsule, < 0.001), and hippocampus ( < 0.05) was identified with PET images at both 3.5 weeks and 5.0 weeks, and validated with autoradiography. No significant uptake differences were detected between 3.5 weeks and 5.0 weeks assessing these regions as a whole, although there was a trend of increased uptake at 5.0 weeks compared to 3.5 weeks in the CC. High F-PBR-111 uptake regions correlated with microglial/macrophage locations by immunofluorescence staining with F4/80 and CD11b antibodies. F-PBR-111 uptake in anatomic locations correlated with activated microglia at histology in the cuprizone mouse model of MS suggests that F-PBR-111 has potential for in vivo evaluation of therapy response and potential for use in MS patients and animal studies.
PubMed: 33925560
DOI: 10.3390/diagnostics11050786 -
Methods in Molecular Biology (Clifton,... 2021Microautoradiography (MAR) is a technique by which assimilated radioactive tracers incorporated into the biomass can be detected by a film emulsion. This allows for the...
Microautoradiography (MAR) is a technique by which assimilated radioactive tracers incorporated into the biomass can be detected by a film emulsion. This allows for the testing of cellular preferences in electron donors and acceptors of individual cells in complex microbial assemblages, as well as the ability to take up substrates under diverse environmental exposures.Combination with staining techniques such as fluorescence in situ hybridization (FISH) can be used to identify the involved cells. Here, the practical aspects of a combined microautoradiography and fluorescence in situ hybridization (MAR-FISH) approach are described.
Topics: Autoradiography; Biomass; Electrons; In Situ Hybridization, Fluorescence; Microbiota; Phylogeny
PubMed: 33576992
DOI: 10.1007/978-1-0716-1115-9_14 -
Methods in Molecular Biology (Clifton,... 2022Despite its development almost 40 years ago, receptor autoradiography remains a regular and reliable practice for the localization of oxytocin and vasopressin receptors...
Despite its development almost 40 years ago, receptor autoradiography remains a regular and reliable practice for the localization of oxytocin and vasopressin receptors in brain tissue sections. It is used across many laboratories, institutions, and animal species to characterize and quantify the distribution and density of these receptors at baseline and/or in response to experimental manipulations or lived experience. This powerful tool and the neuroanatomical receptor maps that it generates have allowed researchers to more accurately investigate and understand the neural substrates upon which oxytocin and vasopressin act to affect behavior. Researchers have used these maps to design site-specific pharmacological manipulations and electrophysiological recordings in animal studies to directly probe the underlying neural mechanisms in this system. This methods chapter describes the specific procedures by which a pharmacologically optimized, competitive binding modification to receptor autoradiography can be used to reliably localize oxytocin and vasopressin receptors in the human brain and in the brains of nonhuman primates. The ability to reliably perform receptor autoradiography for these targets in human brain tissue can finally inform our interpretation of past intranasal oxytocin neuroimaging studies and allows us to move past the reliance on transcriptomic studies using brain tissue homogenates so that we can directly investigate the involvement of oxytocin and vasopressin receptors in human behavior, physiology, and neuropsychiatric disease.
Topics: Animals; Autoradiography; Brain; Humans; Oxytocin; Primates; Receptors, Oxytocin; Receptors, Vasopressin; Vasopressins
PubMed: 34550571
DOI: 10.1007/978-1-0716-1759-5_7 -
International Journal of Molecular... Mar 2023CEND-1 (iRGD) is a bifunctional cyclic peptide that can modulate the solid tumour microenvironment, enhancing the delivery and therapeutic index of co-administered...
CEND-1 (iRGD) is a bifunctional cyclic peptide that can modulate the solid tumour microenvironment, enhancing the delivery and therapeutic index of co-administered anti-cancer agents. This study explored CEND-1's pharmacokinetic (PK) properties pre-clinically and clinically, and assessed CEND-1 distribution, tumour selectivity and duration of action in pre-clinical tumour models. Its PK properties were assessed after intravenous infusion of CEND-1 at various doses in animals (mice, rats, dogs and monkeys) and patients with metastatic pancreatic cancer. To assess tissue disposition, [H]-CEND-1 radioligand was administered intravenously to mice bearing orthotopic 4T1 mammary carcinoma, followed by tissue measurement using quantitative whole-body autoradiography or quantitative radioactivity analysis. The duration of the tumour-penetrating effect of CEND-1 was evaluated by assessing tumour accumulation of Evans blue and gadolinium-based contrast agents in hepatocellular carcinoma (HCC) mouse models. The plasma half-life was approximately 25 min in mice and 2 h in patients following intravenous administration of CEND-1. [H]-CEND-1 localised to the tumour and several healthy tissues shortly after administration but was cleared from most healthy tissues by 3 h. Despite the rapid systemic clearance, tumours retained significant [H]-CEND-1 several hours post-administration. In mice with HCC, the tumour penetration activity remained elevated for at least 24 h after the injection of a single dose of CEND-1. These results indicate a favourable in vivo PK profile of CEND-1 and a specific and sustained tumour homing and tumour penetrability. Taken together, these data suggest that even single injections of CEND-1 may elicit long-lasting tumour PK improvements for co-administered anti-cancer agents.
Topics: Rats; Mice; Animals; Dogs; Carcinoma, Hepatocellular; Liver Neoplasms; Antineoplastic Agents; Infusions, Intravenous; Peptides; Tumor Microenvironment
PubMed: 36982773
DOI: 10.3390/ijms24065700 -
Methods in Molecular Biology (Clifton,... 2021The opioid receptors have been an interesting target for the drug industry for decades. These receptors were pharmacologically characterized in the 1970s and several...
The opioid receptors have been an interesting target for the drug industry for decades. These receptors were pharmacologically characterized in the 1970s and several drugs and peptides have emerged over the years. In 2012, the crystal structures were also demonstrated, with new data on the receptor sites, and thus new possibilities will appear. The role of opioids in the brain has attracted considerable interest in several diseases, especially pain and drug dependence. The opioid receptors are G-protein-coupled receptors (GPCR ) that are Gi coupled which make them suitable for studying the receptor functionality. The [S]GTP γS autoradiography assay is a good option that has the benefit of generating both anatomical and functional data in the area of interest. It is based on the first step of the signaling mechanism of GPCRs. When a ligand binds to the receptor GTP will replace GDP on the a-subunit of the G-protein, leading to a dissociation of the βγ-subunit. These subunits will start a cascade of second messengers and subsequently a physiological response.
Topics: Analgesics, Opioid; Animals; Autoradiography; GTP-Binding Proteins; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Receptors, Opioid; Receptors, Opioid, mu; Signal Transduction; Sulfur Radioisotopes
PubMed: 32975793
DOI: 10.1007/978-1-0716-0884-5_10