scholarly journals A novel antioxidant ergothioneine PET radioligand for in vivo imaging applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
William J. Behof ◽  
Clayton A. Whitmore ◽  
Justin R. Haynes ◽  
Adam J. Rosenberg ◽  
Mohammed N. Tantawy ◽  
...  
Keyword(s):  
Amino Acid ◽  
Mouse Model ◽  
Peripheral Tissues ◽  
Molar Activity ◽  
Model Of Alzheimer’S Disease ◽  
Specific Retention ◽  
5Xfad Mice ◽  
The Brain

AbstractErgothioneine (ERGO) is a rare amino acid mostly found in fungi, including mushrooms, with recognized antioxidant activity to protect tissues from damage by reactive oxygen species (ROS) components. Prior to this publication, the biodistribution of ERGO has been performed solely in vitro using extracted tissues. The aim of this study was to develop a feasible chemistry for the synthesis of an ERGO PET radioligand, [11C]ERGO, to facilitate in vivo study. The radioligand probe was synthesized with identical structure to ERGO by employing an orthogonal protection/deprotection approach. [11C]methylation of the precursor was performed via [11C]CH3OTf to provide [11C]ERGO radioligand. The [11C]ERGO was isolated by RP-HPLC with a molar activity of 690 TBq/mmol. To demonstrate the biodistribution of the radioligand, we administered approximately 37 MBq/0.1 mL in 5XFAD mice, a mouse model of Alzheimer’s disease via the tail vein. The distribution of ERGO in the brain was monitored using 90-min dynamic PET scans. The delivery and specific retention of [11C]ERGO in an LPS-mediated neuroinflammation mouse model was also demonstrated. For the pharmacokinetic study, the concentration of the compound in the serum started to decrease 10 min after injection while starting to distribute in other peripheral tissues. In particular, a significant amount of the compound was found in the eyes and small intestine. The radioligand was also distributed in several regions of the brain of 5XFAD mice, and the signal remained strong 30 min post-injection. This is the first time the biodistribution of this antioxidant and rare amino acid has been demonstrated in a preclinical mouse model in a highly sensitive and non-invasive manner.

scholarly journals Synthesis and preclinical evaluation of [11C]MTP38 as a novel PET ligand for phosphodiesterase 7 in the brain

2020 ◽  
Author(s):  
Naoyuki Obokata ◽  
Chie Seki ◽  
Takeshi Hirata ◽  
Jun Maeda ◽  
Hideki Ishii ◽  
...  
Keyword(s):  
Arterial Input Function ◽  
Inflammatory Diseases ◽  
Input Function ◽  
Binding Potential ◽  
Dependent Manner ◽  
Reference Tissue ◽  
Molar Activity ◽  
The Brain

AbstractPurposePhosphodiesterase (PDE) 7 is a potential therapeutic target for neurological and inflammatory diseases, although in-vivo visualization of PDE7 has not been successful. In this study, we aimed to develop [11C]MTP38 as a novel positron emission tomography (PET) ligand for PDE7.Methods[11C]MTP38 was radiosynthesized by 11C-cyanation of a bromo precursor with [11C]HCN. PET scans of rat and rhesus monkey brains and in-vitro autoradiography of brain sections derived from these species were conducted with [11C]MTP38. In monkeys, dynamic PET data were analyzed with an arterial input function to calculate the total distribution volume (VT). The non-displaceable binding potential (BPND) in the striatum was also determined by a reference tissue model with cerebellar reference. Finally, striatal occupancy of PDE7 by an inhibitor was calculated in monkeys according to changes in BPND.Results[11C]MTP38 was synthesized with radiochemical purity ≥ 99.4% and molar activity of 38.6 ± 12.6 GBq/μmol. Autoradiography revealed high radioactivity in the striatum and its reduction by non-radiolabeled ligands, in contrast with unaltered autoradiographic signals in other regions. In-vivo PET after radioligand injection to rats and monkeys demonstrated that radioactivity was rapidly distributed to the brain and intensely accumulated in the striatum relative to the cerebellum. Correspondingly, estimated VT values in the monkey striatum and cerebellum were 3.59 and 2.69 mL/cm3, respectively. The cerebellar VT value was unchanged by pretreatment with unlabeled MTP38. Striatal BPND was reduced in a dose-dependent manner after pretreatment with MTP-X, a PDE7 inhibitor. Relationships between PDE7 occupancy by MTP-X and plasma MTP-X concentration could be described by Hill’s sigmoidal function.ConclusionWe have provided the first successful preclinical demonstration of in-vivo PDE7 imaging with a specific PET radioligand. [11C]MTP38 is a feasible radioligand for evaluating PDE7 in the brain and is currently being applied to a first-in-human PET study.

scholarly journals Increased levels of Stress-inducible phosphoprotein-1 accelerates amyloid-β deposition in a mouse model of Alzheimer’s disease

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Rachel E. Lackie ◽  
Jose Marques-Lopes ◽  
Valeriy G. Ostapchenko ◽  
Sarah Good ◽  
Wing-Yiu Choy ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Protein Quality ◽  
Amyloid Β ◽  
Amyloid Burden ◽  
C Elegans ◽  
Model Of Alzheimer’S Disease

Abstract Molecular chaperones and co-chaperones, which are part of the protein quality control machinery, have been shown to regulate distinct aspects of Alzheimer’s Disease (AD) pathology in multiple ways. Notably, the co-chaperone STI1, which presents increased levels in AD, can protect mammalian neurons from amyloid-β toxicity in vitro and reduced STI1 levels worsen Aβ toxicity in C. elegans. However, whether increased STI1 levels can protect neurons in vivo remains unknown. We determined that overexpression of STI1 and/or Hsp90 protected C. elegans expressing Aβ(3–42) against Aβ-mediated paralysis. Mammalian neurons were also protected by elevated levels of endogenous STI1 in vitro, and this effect was mainly due to extracellular STI1. Surprisingly, in the 5xFAD mouse model of AD, by overexpressing STI1, we find increased amyloid burden, which amplifies neurotoxicity and worsens spatial memory deficits in these mutants. Increased levels of STI1 disturbed the expression of Aβ-regulating enzymes (BACE1 and MMP-2), suggesting potential mechanisms by which amyloid burden is increased in mice. Notably, we observed that STI1 accumulates in dense-core AD plaques in both 5xFAD mice and human brain tissue. Our findings suggest that elevated levels of STI1 contribute to Aβ accumulation, and that STI1 is deposited in AD plaques in mice and humans. We conclude that despite the protective effects of STI1 in C. elegans and in mammalian cultured neurons, in vivo, the predominant effect of elevated STI1 is deleterious in AD.

Netrin-1 Interrupts Amyloid-β Amplification, Increases sAβPPα in vitro and in vivo, and Improves Cognition in a Mouse Model of Alzheimer’s Disease

2016 ◽  
Vol 52 (1) ◽  
pp. 223-242 ◽  
Author(s):  
Patricia R. Spilman ◽  
Veronique Corset ◽  
Olivia Gorostiza ◽  
Karen S. Poksay ◽  
Veronica Galvan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Β ◽  
Model Of Alzheimer’S Disease

scholarly journals Snca-GFP knock-in mice reflect patterns of endogenous expression and pathological seeding

2020 ◽  
Author(s):  
Anna Caputo ◽  
Yuling Liang ◽  
Tobias D. Raabe ◽  
Angela Lo ◽  
Mian Horvath ◽  
...  
Keyword(s):  
Mouse Model ◽  
Fusion Protein ◽  
Synaptic Vesicle ◽  
Alpha Synuclein ◽  
Peripheral Tissues ◽  
Endogenous Expression ◽  
Sequence Of Events ◽  
Gfp Fusion Protein

AbstractAlpha-synuclein (aSyn) participates in synaptic vesicle trafficking and synaptic transmission, but its misfolding is also strongly implicated in Parkinson’s disease (PD) and other neurodegenerative disorders known as synucleinopathies where misfolded aSyn accumulates in different regions of the central and peripheral nervous systems. Although increased aSyn expression levels or altered aggregation propensities likely underlie familial PD with SNCA amplification or mutations, the majority of synucleinopathies arise sporadically, indicating that disease can develop under normal levels of wildtype aSyn. We report here the development and characterization of a mouse line expressing an aSyn-GFP fusion protein under the control of native Snca regulatory elements. Regional and subcellular localization of the aSyn-GFP fusion protein in brains and peripheral tissues of knock-in (KI) mice are indistinguishable from that of wildtype littermates. Importantly, similar to wildtype aSyn, aSyn-GFP disperses from synaptic vesicles upon membrane depolarization, indicating that the tag does not alter normal aSyn dynamics at synapses. In addition, intracerebral injection of aSyn pre-formed fibrils into KI mice induced the formation of aSyn-GFP inclusions with a distribution pattern similar to that observed in wildtype mice, albeit with attenuated kinetics due to the GFP tag. We anticipate that this new mouse model will facilitate in vitro and in vivo studies requiring in situ detection of endogenous aSyn, therefore providing new insights into aSyn function in health and disease.Significance StatementAlpha-synuclein (aSyn) participates in synaptic vesicle function and represents a major component of the Lewy pathology found in Parkinson’s and related neurodegenerative diseases. The function of aSyn and the sequence of events leading to its aggregation and neurotoxicity are not fully understood. Here we present a new mouse model in which Enhanced Green Fluorescence Protein (GFP) has been knocked-in at the C-terminal of the Snca gene. The resulting fusion protein shows identical expression and localization to that of wildtype animals, is functional, and is incorporated into pathological aggregates in vitro and in vivo. This new tool allows for monitoring aSyn under a variety of physiological and pathological conditions, and may uncover additional insights into its function and dysfunction.

scholarly journals Changes of Cholinesterase Activity in the Erythrocytes, Plasma, Diaphragm, Liver and Various Parts of the Brain in the Rabbit Following Transfusion of Erythrocytes with Soman Inhibited Acetylcholinesterase

1997 ◽  
Vol 40 (2) ◽  
pp. 37-39
Author(s):  
Jiří Kassa ◽  
Jiří Bajgar ◽  
Josef Fusek
Keyword(s):  
Blood Transfusion ◽  
Cholinesterase Activity ◽  
Acetylcholinesterase Activity ◽  
Significant Inhibition ◽  
Peripheral Compartment ◽  
Peripheral Tissues ◽  
Cholinesterase Activities ◽  
The Brain

1. The changes of cholinesterase activity in rabbit blood, peripheral tissues and the central nervous system following transfusion of erythrocytes with soman inhibited acetylcholinesterase were demonstrated. 2. After incubation with soman for 0.5 or 24 h, erythrocytes without acetylcholinesterase activity were injected to intact rabbits and cholinesterase activity in the erythrocytes, plasma, diaphragm, liver and various parts of the brain were evaluated 24 h following blood-transfusion. 3. When erythrocytes were incubated with soman for 24 h, no changes of cholinesterase activity in the rabbit following blood-transfusion were observed with an exception of erythrocyte acetylcholinesterase. 4. When erythrocytes were incubated with soman for 0.5 h, a significant decrease in cholinesterase activity in the erythrocytes, plasma, diaphragm and liver following blood-transfusion was found. These data show that soman is able to release from erythrocytes and inhibit cholinesterase activities not only in vitro but also in vivo although the significant inhibition of cholinesterase activities by soman was only observed in the peripheral compartment.

scholarly journals Azole Heteroresistance in Cryptococcus neoformans: Emergence of Resistant Clones with Chromosomal Disomy in the Mouse Brain during Fluconazole Treatment

2013 ◽  
Vol 57 (10) ◽  
pp. 5127-5130 ◽  
Author(s):  
Edward Sionov ◽  
Yun C. Chang ◽  
Kyung J. Kwon-Chung
Keyword(s):  
Mouse Model ◽  
Cryptococcus Neoformans ◽  
Mouse Brain ◽  
Content Type ◽  
The Brain ◽  
Strain Dependent ◽  
Is Strain

ABSTRACTWe have previously reported thatCryptococcus neoformansstrains are innately heteroresistant to fluconazolein vitro, producing minor, highly resistant subpopulations due to adaptive formation of disomic chromosomes. Using a mouse model, we assessed the emergence of heteroresistant clones in the brain during fluconazole treatment and found that the occurrence of heteroresistant clonesin vivowith chromosomal disomy is strain dependent. Interestingly, emergence of heteroresistant clonesin vivowas unrelated to the strain's MIC to fluconazole.

scholarly journals A General Approach to Convert Hemicyanine Dyes into Highly Optimized Photoacoustic Scaffolds for Analyte Sensing

2021 ◽  
Author(s):  
Sarah Garder ◽  
Catharine Brady ◽  
Cameron Keeton ◽  
Anuj K Yadav ◽  
Sharath C Mallojjala ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Photoacoustic Imaging ◽  
Disease Model ◽  
Photoacoustic Signal ◽  
Model Of Alzheimer’S Disease ◽  
5Xfad Mice ◽  
The Impact

<p>In the context of deep-tissue disease biomarker detection and analyte sensing of biologically relevant species, the impact of photoacoustic imaging has been profound. However, most photoacoustic imaging agents to date are based on the repurposing of existing fluorescent dye platforms that exhibit non-optimal properties for photoacoustic applications (e.g., high fluorescence quantum yield). Herein, we introduce two effective modifications to the hemicyanine dye to afford PA-HD, a new dye scaffold optimized for photoacoustic probe development. We observed a significant increase in the photoacoustic output, representing an increase in sensitivity of 4.8-fold and a red-shift of the λ<sub>abs</sub> from 690 nm to 745 nm to enable ratiometric imaging. Moreover, to demonstrate the generalizability and utility of our remodeling efforts, we developed three probes using common analyte-responsive triggers for beta-galactosidase activity (PA-HD-Gal), nitroreductase activity (PA-HD-NTR), and hydrogen peroxide (PA-HD-H<sub>2</sub>O<sub>2</sub>). The performance of each probe (responsiveness, selectivity) was evaluated <i>in vitro</i> and <i>in cellulo</i>. To showcase the enhance properties afforded by PA-HD for <i>in vivo</i> photoacoustic imaging, we employed an Alzheimer’s disease model to detect H<sub>2</sub>O<sub>2</sub>. In particular, the photoacoustic signal at 735 nm in the brains of 5xFAD mice (a murine model of Alzheimer’s disease) increased by 1.72 ± 0.20-fold relative to background indicating the presence of oxidative stress, whereas the change in wildtype mice was negligible (1.02 ± 0.14). These results were confirmed via ratiometric calibration which was not possible using the parent HD platform.</p>

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