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Shegani A, Kealey S, Luzi F, Basagni F, Machado JDM, Ekici SD, Ferocino A, Gee AD, Bongarzone S. Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds. Chem Rev 2022; 123:105-229. [PMID: 36399832 PMCID: PMC9837829 DOI: 10.1021/acs.chemrev.2c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.
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Affiliation(s)
- Antonio Shegani
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Steven Kealey
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Federico Luzi
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Filippo Basagni
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−University of Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | - Joana do Mar Machado
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Sevban Doğan Ekici
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Alessandra Ferocino
- Institute
of Organic Synthesis and Photoreactivity, Italian National Research Council, via Piero Gobetti 101, 40129 Bologna, Italy
| | - Antony D. Gee
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,A.G.: email,
| | - Salvatore Bongarzone
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,S.B.:
email,
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Thomas AS, Sassi M, Angelini R, Morgan AH, Davies JS. Acylation, a Conductor of Ghrelin Function in Brain Health and Disease. Front Physiol 2022; 13:831641. [PMID: 35845996 PMCID: PMC9280358 DOI: 10.3389/fphys.2022.831641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/31/2022] [Indexed: 11/22/2022] Open
Abstract
Acyl-ghrelin (AG) is an orexigenic hormone that has a unique octanoyl modification on its third serine residue. It is often referred to as the “hunger hormone” due to its involvement in stimulating food intake and regulating energy homeostasis. The discovery of the enzyme ghrelin-O-acyltransferase (GOAT), which catalyses ghrelin acylation, provided further insights into the relevance of this lipidation process for the activation of the growth hormone secretagogue receptor (GHS-R) by acyl-ghrelin. Although acyl-ghrelin is predominantly linked with octanoic acid, a range of saturated fatty acids can also bind to ghrelin possibly leading to specific functions. Sources of ghrelin acylation include beta-oxidation of longer chain fatty acids, with contributions from fatty acid synthesis, the diet, and the microbiome. In addition, both acyl-ghrelin and unacyl-ghrelin (UAG) have feedback effects on lipid metabolism which in turn modulate their levels. Recently we showed that whilst acyl-ghrelin promotes adult hippocampal neurogenesis and enhances memory function, UAG inhibits these processes. As a result, we postulated that the circulating acyl-ghrelin:unacyl-ghrelin (AG:UAG) ratio might be an important regulator of neurogenesis and cognition. In this review, we discuss emerging evidence behind the relevance of ghrelin acylation in the context of brain physiology and pathology, as well as the current challenges of identifying the provenance of the acyl moiety.
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Altinoz MA, Ozpinar A, Seyfried TN. Caprylic (Octanoic) Acid as a Potential Fatty Acid Chemotherapeutic for Glioblastoma. Prostaglandins Leukot Essent Fatty Acids 2020; 159:102142. [PMID: 32512365 DOI: 10.1016/j.plefa.2020.102142] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/01/2020] [Accepted: 05/25/2020] [Indexed: 12/18/2022]
Abstract
High grade glial tumors (HGGs) including anaplastic astrocytoma (WHO Grade-III) and glioblastoma multiforme (GBM, WHO Grade-IV) are among the most malignant cancers known to man. Due to their defective mitochondria, HGG cells consume glucose via glycolysis even in the presence of oxygen. Overall survival is worse in HGG patients that are hyperglycemic. Unlike normal neural cells, HGG cells cannot efficiently metabolize ketone bodies for energy. Thus, a metabolic treatment based on therapeutic ketosis (reduced glucose with elevated ketone bodies) was proposed to treat GBM and was supoported from preclinical studies. Caprylic (octanoic) acid, a monocarboxylated saturated fatty acid, is among the best producers of ketone bodies and induces necrosis of experimental tumors at high dose. Caprylic acid is enriched in coconut and in goat's milk. It is also a posttranslational modifier of the ghrelin hormone and is produced in trace amounts in human tissues. Caprylic acid is a straight-chain isomer of the antiepileptic valproic acid, which is used in treatment of HGG-associated seizures and which may increase survival in GBM patients according to epidemiological observations. Among the valproic acids analogs tested, caprylic acid is the most potent molecule to block C6 astrocytoma cell growth in vitro and accumulates selectively within glial cells as shown by Positron Emission Tomography in vivo. Caprylic acid blocks glycolysis both in healthy liver and in malignant liver cells, which is more prominent in the latter and also lowers blood glucose. Noteworthy, caprylic acid exerts neuroprotective- and mitochondria-protective effects in several models of neurodegenerative diseases. Boost injections of caprylic acid at non-toxic levels during classical ketogenic metabolic therapy may fortify antitumor actions and reduce systemic toxicity by differential programming of mitochondrial and other metabolic pathways.
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Affiliation(s)
- Meric A Altinoz
- Department of Biochemistry, Acibadem University, Istanbul, Turkey; Department of Psychiatry, Maastricht University, Maastricht, Holland.
| | - Aysel Ozpinar
- Department of Biochemistry, Acibadem University, Istanbul, Turkey
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Shang Y, Chen L, Toborek M, Yu G. Diffuse optical monitoring of repeated cerebral ischemia in mice. OPTICS EXPRESS 2011; 19:20301-15. [PMID: 21997041 PMCID: PMC3495871 DOI: 10.1364/oe.19.020301] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/09/2011] [Accepted: 09/09/2011] [Indexed: 05/18/2023]
Abstract
Occlusions of bilateral common carotid arteries (bi-CCA) in mice are popular models for the investigation of transient forebrain ischemia. Currently available technologies for assessing cerebral blood flow (CBF) and oxygenation in ischemic mice have limitations. This study tests a novel near-infrared diffuse correlation spectroscopy (DCS) flow-oximeter for monitoring both CBF and cerebral oxygenation in mice undergoing repeated transient forebrain ischemia. Concurrent flow measurements in a mouse brain were first conducted for validation purposes; DCS measurement was found highly correlated with laser Doppler measurement (R2 = 0.94) and less susceptible to motion artifacts. With unique designs in experimental protocols and fiber-optic probes, we have demonstrated high sensitivities of DCS flow-oximeter in detecting the regional heterogeneity of CBF responses in different hemispheres and global changes of both CBF and cerebral oxygenation across two hemispheres in mice undergoing repeated 2-minute bi-CCA occlusions over 5 days. More than 75% CBF reductions were found during bi-CCA occlusions in mice, which may be considered as a threshold to determine a successful bi-CCA occlusion. With the progress of repeated 2-minute bi-CCA occlusions over days, a longitudinal decline in the magnitudes of CBF reduction was observed, indicating the brain adaptation to cerebral ischemia through the repeated preconditioning.
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Affiliation(s)
- Yu Shang
- Center for Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506,
USA
| | - Lei Chen
- Department of Neurosurgery, University of Kentucky, Lexington, Kentucky 40536,
USA
| | - Michal Toborek
- Department of Neurosurgery, University of Kentucky, Lexington, Kentucky 40536,
USA
| | - Guoqiang Yu
- Center for Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506,
USA
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Kuge Y, Hikosaka K, Seki KI, Ohkura K, Nishijima KI, Tsukamoto E, Tamaki N. In vitro uptake of [1-14C]Octanoate in brain slices of rats: basic studies for assessing [1-11C]Octanoate as a PET tracer of glial functions. Nucl Med Biol 2002; 29:303-6. [PMID: 11929699 DOI: 10.1016/s0969-8051(01)00309-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To clarify the contribution of glial cells to octanoate uptake into the brain, we determined the effects of fluoroacetate, a selective inhibitor of glial metabolism, on in vitro brain uptake of [1-14C]octanoate, using rat brain slices. The [1-14C]octanoate uptake significantly decreased, depending on the concentration of fluoroacetate (p = 0.001). The [1-14C]octanoate uptakes at 5 mM (0.23 +/- 0.05% uptake/mg slice) and 25 mM fluoroacetate (0.12 +/- 0.01% uptake/mg slice) were significantly lower than that at control (0.29 +/- 0.02% uptake/mg slice, p < 0.05 and p < 0.001, respectively). The results demonstrate the contribution of glial cells to octanoate uptake into the brain. The potential of [1-11C]octanoate as a PET tracer for studying glial functions is suggested.
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Affiliation(s)
- Yuji Kuge
- Department of Tracer Kinetics, Graduate School of Medicine, Hokkaido University, Kita 15 Nishi 7, Kita-ku, 060-8638, Sapporo, Japan.
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Abstract
The current status and challenges of small animal non-invasive imaging is briefly reviewed. The advantages of non-invasive studies on living animals versus post-mortem studies are evaluated. An argument is advanced that even in post-mortem situations, non-invasive imaging may play an important role in efficiently characterizing small animal phenotypes as well as pathology. Issues of data interpretation under anesthetized conditions in live animal studies are also reviewed. The five imaging technologies covered include CT, PET, ultrasound, MRI and optical imaging. The structural and physiological information content of these different modalities is reviewed along with the ability of these techniques to scale down for use in small mammals such as mice and rats. In general, it was found that most of these technologies scale favorably to the study of small mammals, generally providing more physiological information than when used on the larger human scale. This suggests that these types of small mammal imaging capabilities will play a very significant role in the full utilization of these important animal models in biomedical research.
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Affiliation(s)
- R S Balaban
- Laboratory Research Program, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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