Misfolded superoxide dismutase-1 (mSOD1) is an abnormal protein observed in amyotrophic lateral sclerosis (ALS) and constitutes a therapeutic target. The present study evaluated the biodistribution, dosimetry, and safety of a new antibody-based radiopharmaceutical, [89Zr]Zr-DFO-AP-101, targeting mSOD1. Seven control participants and one patient with ALS received 41 ± 3 MBq of [89Zr]Zr-DFO-AP-101. They were followed up with five whole-body positron emission tomography (PET) scans over 10 days. Semi-automatic segmentation was performed on the images to derive time-activity curves, radiotracer effective half-life and dose exposure. Total elimination of the radiotracer (urinary and hepatobiliary) was 25–30

BACKGROUND:APPE693Q ("Dutch") transgenic mice develop aging-related learning deficits and accumulate endogenously generated non-fibrillar aggregates (NFAs) of amyloid beta (Aβ) and amyloid precursor protein α-carboxy terminal fragments. NFA-Aβ correlates with synaptic loss and memory deficits more closely than does fibrillar Aβ. METHODS:We assessed the physiological, transcriptomic, ultrastructural, histological, and metabolic changes associated with the accumulation of NFA of Dutch Aβ in brains of APPE693Q mice. RESULTS:Aging-related accumulation of NFA-Aβ in APPE693Q mice was revealed by A11 immunohistochemistry and cyclic D,L-α-peptide-fluorescein-5-isothiocyanate microscopy. Presynaptic termini of APPE693Q mice developed physiological abnormalities in post-tetanic potentiation, synaptic fatigue, synaptic vesicle replenishment, and an aging-related reduction in mitochondrial complex I activity. Single-cell RNA sequencing showed that excitatory neurons exhibited an altered transcriptomic profile involving "protein translation" and "oxidative phosphorylation." DISCUSSION:Accumulation of NFA-Aβ alters neuronal metabolism but does not activate inflammation. Depletion of all forms of Aβ may be required to eliminate Aβ toxicity with anti-amyloid antibodies.

Objectives Rheumatoid arthritis (RA) is the most prevalent form of immune mediated inflammatory arthritis. It affects close to 1% of Canadian.[1] DMARD therapies are currently guided by a trial-and-error approach to identify the most suitable treatment for each patient. Despite the fast evolution and the high number of available therapy options, the management of rheumatoid symptoms is still challenging. Approximately 30-40% of RA patients do not respond to the first-line treatment.[2] This trial-and-error strategy allows disease progression and may lead to irreversible joint damage due to sustained inflammation. These permanent changes directly affect patients’ well-being and autonomy, ultimately increasing healthcare costs for society. The TNF-α is an inflammation mediator and a key player in inflammatory diseases such as rheumatoid arthritis.[3] TNF-α is found in 50-70 % of RA patients at elevated level in synovial tissues. A phase III clinical trial previously demonstrated that adalimumab, an anti-TNF-α monoclonal antibody, elicited a strong therapeutic response in approximately 60% of RA patients (ACR20).[3] Based on this observation, we postulate that adalimumab could be used to develop an imagery technique to identify patients with the higher level of TNF-α. This tool could be a game changer to pursue personalized therapy and avoid unnecessary therapeutics. Methods In this study we proposed to conjugate a commercial anti-TNF-α antibody (Yuflima, containing adalimumab; Celltrion) with a radiomaker 89 zirconium coupled with a DFO chelator. The 89Zr-DFO-Adalumimab will be used in PET (positron emission tomography) imagery to identify RA patients expressing elevated level of TNf-α in the joint. Results We successfully conjugated the radiomarker Zirconium 89 to the Adalumimab antibody. Preliminary results show that the conjugate DFO-Adalumimab is still able to target TNF-α with the same affinity as the commercial adalimumab. Conclusion These promising findings will enable us to test 89Zr-DFO-adalimumab in a collagen-induced arthritis (CIA) mouse model (DBA/1 strain) to assess inflammation at the join levels using PET imaging. References [1.] Government of Canada. https://www.canada.ca/en/public-health/services/publications/diseases-conditions/rheumatoid-arthritis.html [2.] Babaahmadi M. Stem Cell Res Ther 2023;14:268. [3.] Wang Z. Front Immunol 2021;12:755844.

Combining gold nanoparticles (AuNPs) with 10-100 keV X-rays has shown considerable potential for radiotherapy. The uptake of AuNPs in cancer tissues is influenced by their size, with smaller sizes exhibiting enhanced penetration capabilities into deeper layers of cancer tissue compared to larger AuNPs. In this study, we examine the effect of nanoparticle (NP) size with respect to the formation of various types of DNA damage upon X-ray exposure of dried AuNP-oligo-DNA mixtures. The type and yield of DNA damage is measured using LC-MS/MS. The most important type of damage involves the release of nucleobases (Cyt > Ade ≈ Thy > Gua), which accounts for 82% of the total measured damage. The remaining 18% includes reduction products of pyrimidines (5,6-dihydrothymidine and 5,6-dihydro-2'-deoxyuridine), oxidative products (8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxoG) and 5-hydroxymethyl-2'-deoxyuridine (5hmU)), and novel electron-specific products, including eight 2',3'- and 2',5'-dideoxynucleosides (ddNs). The presence of AuNP in close contact with DNA results in a shift of radiation-induced damage toward that mediated by electrons. Moreover, the yield of damage depends on the size of the NP, with much more damage (7-10-fold) observed for NPs with a small diameter (5 nm) compared to those with a large diameter (110 nm). The dependence of DNA damage with NP size is partly attributed to the energy of electrons emitted from the surface of AuNPs and the distance required to reach available sites of electron attachment. This study contributes to elucidate the mechanisms of AuNP radiosensitization and should aid in designing optimal NP sizes for radiotherapy.

Background/Objectives: This study explores the potential of the inducible G protein-coupled kinin B1 receptor (B1R) as a target for the diagnosis and treatment of prostate cancer (PCa) and aims to develop the first theranostic agent targeting hB1R for both molecular imaging and radionuclide therapy. Methods: B1R expression was analyzed via qPCR and immunohistochemistry in human PCa cells and tissues specimens. A novel 64Cu/NOTA-conjugated peptide analog of the potent B1R antagonist R954 was synthetized and evaluated in vitro and in vivo. Results: B1R was confirmed to be expressed (RNA, protein) by varying degrees in all PCa cell lines and tissues investigated, with protein level significantly correlating with tumor grades. This finding was supported by similar analyses from the TCGA and MSKCC databases. In vitro, the 64Cu/NOTA-βAla-R954 conjugate showed nanomolar affinity/potency at hB1R, complete plasma stability over 24 h, significant cellular uptake (up to 33% of ID at 24 h), and dose-dependent anti-clonal growth effects. In vivo, the radioconjugate remained stable in circulation for up to 90 min and was primarily excreted intact via the kidneys following IV administration. Intravenous 64Cu/NOTA-βAla-R954 (7.5 MBq) effectively detected subcutaneous PCa xenografts via µPET imaging in male athymic nude mice. At a single higher dose (65 MBq; 50 µg/kg), it significantly reduced tumor growth without observable toxicity. This antitumor effect was associated with increased apoptosis (active caspase-3) and reduced proliferation (Ki67), as shown by immunohistochemistry. In contrast, the nonradioactive NatCu/NOTA-βAla-R954 had no therapeutic effect at the same dose. Conclusions: Our findings provide proof-of-concept for the potential theranostic use of 64Cu/NOTA-R954 in PCa, and potentially other types of B1R-positive solid cancers.

Glioblastoma multiforme (GBM) remains one of the most aggressive and treatment-resistant brain tumors, with poor prognosis and limited therapeutic options. Background/Objectives: Integrin αvβ3, a cell surface receptor overexpressed in GBM, specifically binds to cyclic arginine-glycine-aspartate-D-phenylalanine-lysine (c(RGDfK)) motif, making it a valuable target for tumor-specific delivery and PET imaging. This study explores a novel radiotheranostic agent, [64Cu]Cu-NOTA-TP-c(RGDfK), which combines the imaging and therapeutic capabilities of copper-64 (64Cu) and the cytotoxic activity of a terpyridine-platinum (TP) complex, conjugated to c(RGDfK). Methods: A robust protocol was developed for the small-scale preparation of NOTA-TP-c(RGDfK). Comparative cellular studies were conducted using U87 MG glioblastoma (GBM) cells and SVG p12 human astrocytes to evaluate the performance of [64Cu]Cu-NOTA-TP-c(RGDfK) relative to [64Cu]Cu-NOTA-c(RGDfK), [64Cu]Cu-NOTA-TP, natCu-NOTA-TP-c(RGDfK), cisplatin, and temozolomide. Results: 64Cu-radiolabeling of NOTA-TP-c(RGDfK) was achieved with >99% radiochemical purity, and competition assays confirmed high binding affinity to integrin αvβ3 (IC50 = 16 ± 8 nM). Cellular uptake, internalization, and retention studies demonstrated significantly higher accumulation of [64Cu]Cu-NOTA-TP-c(RGDfK) in U87 MG cells compared to control compounds, with 38.8 ± 1.8% uptake and 28.0 ± 1.0% internalization at 24 h. Nuclear localization (6.0 ± 0.5%) and stable intracellular retention further support its therapeutic potential for inducing localized DNA damage. Importantly, [64Cu]Cu-NOTA-TP-c(RGDfK) exhibited the highest cytotoxicity in U87 MG cells (IC50 = 10 ± 2 nM at 48 h), while maintaining minimal toxicity in normal SVG p12 astrocytes. Conclusions: These results highlight [64Cu]Cu-NOTA-TP-c(RGDfK) as a promising targeted radiotheranostic agent for GBM, warranting further preclinical development

Galectins play significant roles in regulating immune responses, posing challenges for cancer immunotherapy. The development of galectin inhibitors has been limited by their high structural homology and the lack of noninvasive imaging tools to identify potential responsive patients. We developed 12 galectin-7-specific inhibitors using nanobodies (Nbs) and identified G7N8 as the lead Nb. G7N8 was conjugated with the NOTA chelator, labeled with copper-64 ([64Cu]Cu), and used as a radiotracer for PET imaging in a triple-negative breast cancer (TNBC) mouse model. Nbs demonstrated high affinity for galectin-7, with no binding activity for other galectins tested. The lead Nbs inhibited galectin-7 binding to T-cell glycoreceptors and reduced subsequent apoptosis. PET imaging with [64Cu]Cu-NOTA-G7N8 showed selective radiotracer accumulation at 20 h (P = 0.001). We developed galectin-7-specific Nbs that inhibit T-cell apoptosis and enable PET imaging of TNBC, providing novel tools for investigating immune regulation and enhancing cancer immunotherapy.

Studies of Alzheimer's disease have demonstrated that cognitive decline fails to correlate with fibrillar Aβ burden. We created a transgenic mouse overexpressing Dutch mutant hAPP (APPE693Q) driven by a pan-neuronal Thy1 promoter. Accumulation of oligomeric Aβ (oAβ) and alpha-CTFs (but not Aβ fibrils) was observed in the brains of Dutch mice which develop impaired learning behavior proportional to brain oAβ levels. Male & female Dutch mice & WT controls were compared using learning behavior, ICC, transmission electron microscopy (TEM), electrophysiology, epitomic assays & single cell RNA sequencing. Brain levels of nonfibrillar oAβ in Dutch mice increased during aging as revealed by A11 ICC and FITC-cyclic peptide (FITC-CP) fluorescence microscopy. Electrophysiology of hippocampal synapses in Dutch and WT mice at ∼7 & ∼11 months revealed no change in basal excitatory transmission consistent with normal density & morphology of synapses in hippocampal CA1. One exception was increased postsynaptic density area in Dutch mice. Functional characterization of presynaptic termini showed abnormal post-tetanic potentiation, synaptic fatigue & vesicle replenishment in Dutch mice. Single cell RNA-seq to elucidate cell-type specific transcriptional responses to oAβ revealed altered transcriptional profiles in multiple cell types. Unexpectedly, no obvious transcriptomic differences existed between Dutch vs WT microglia. Excitatory neurons showed the most altered profile which was associated with 'protein translation' & 'oxidative phosphorylation'. Mitochondrial complex I activity was reduced in 12- but not 7-mo-old Dutch vs WT mice. Ultrastructural analysis of excitatory presynaptic mitochondria revealed fewer mitochondria in Dutch mouse presynaptic termini. Nonfibrillar oAβ deposits were revealed by co-localization of A11 immunoreactivity with FITC-CP microscopy. Oligomer-detecting cyclic azaglycine PET tracer Lys(64Cu/NOTA)]-CP revealed robust PET signal from thalami and cerebral cortices of presymptomatic 5xFAD mice (10.1073/pnas.2210766119). Analysis using TEM and CP-gold nanoparticle labeling revealed that oAβ was concentrated around mitochondria & ER in Dutch mice. Dutch oAβ accumulation associates with aging-related defects in learning behavior, presynaptic function & mitochondrial structure & function. Brain PET imaging with Lys(64Cu /NOTA)]-CP may enable development of an assay for monitoring oAβ levels & distribution for diagnosing living human subjects & patients.

BACKGROUND:Preclinical models of brain tumors play a fundamental role in understanding tumor biology and deploying anti-tumor strategies. However, preclinical studies evaluate their potential therapy in tumor model without prior resection. Nevertheless, maximal safe resection, the first step in the clinical treatment of glioblastoma (GBM), is known to have a significant effect on adjuvant treatments. NEW METHOD:We have therefore characterized two techniques to perform tumor resection in F98 glioma-bearing rats to bring this model closer to the clinical context. A total of 65 animals were assigned in 5 different groups: control, catheter (1.74 mm diameter) and biopsy punch (1.5/ 2.5/ 3 mm diameter). On day 10 post-tumor implantation, some animals were sacrificed on day 11 for histological analysis whereas the remaining animals were used for survival estimates. RESULTS:All animals in the survival groups that underwent tumor resection recurred. The resection cavities were visible on the H&E histological sections. No significant difference was observed between the control and resection groups in term of survival but there was a trend towards improved survival with increasing tool diameter. COMPARISON WITH EXISTING METHODS:Few studies have investigated the development of tumor resection models, but the majority of these techniques require sophisticated equipment. To our knowledge, we are the first to develop an easy-to-perform partial tumour resection model using the Fischer-F98 glioma model. CONCLUSIONS:Here we present a detailed characterization of the tumor resection procedure and recurrence model, which has potential for the investigation of local delivery strategies in the treatment of GBM.

Galectin-1 (GAL-1) plays a crucial role in cancer biology, especially in triple-negative breast cancer (TNBC), where it facilitates immune evasion and tumor progression. This study presents G1N1, a novel nanobody that specifically targets GAL-1 and exhibits remarkable affinity and selectivity. G1N1 effectively inhibits GAL-1-induced apoptosis in T cells while leaving GAL-7-induced apoptosis unaffected. Preclinical positron emission tomography (PET) imaging studies indicate that the radiolabeled [64Cu]-Cu-NOTA-G1N1 accumulates significantly in breast cancer tumors, highlighting its potential for diagnostic imaging and therapeutic monitoring. Transcriptomic analyses suggest that G1N1 may counteract GAL-1-induced immunosuppression and downregulate chemoresistance-associated genes, particularly those involved in the NF-κB/TNFα signaling pathway, while also decreasing the expression of prometastatic genes like MMP-3. In conclusion, G1N1's dual functionality as a diagnostic and therapeutic agent emphasizes its promise in personalized medicine, potentially enhancing clinical management strategies for TNBC and other aggressive cancers.

Copper plays a critical role in cancer biology, with tumor cells exhibiting abnormal copper metabolism that drives proliferation and tumor growth. A limited number of preclinical and clinical studies have reported promising theranostic potential of copper-based radionuclides, such as 64Cu, for both diagnostic imaging and targeted radiotherapy in diverse cancers, including prostate cancer (PCa). In this work, we evaluated the cellular uptake and antitumor efficacy of [64Cu]Cu-acetate using both cellular and animal models of PCa. Uptake assays revealed that ~70% of the administered dose (10 kBq) was internalized by PC-3 cells within 24 h, predominantly localizing to the cytoplasm, with around 9% detected in the nucleus. These results were corroborated by comparable natural Cu-acetate uptake levels (at equimolar dose) in PC-3 cells, as quantified by ICP-MS. Clonogenic assays revealed a dose-dependent reduction in survival following treatment with [64Cu]Cu-acetate (3 and 6 MBq), whereas its non-radioactive counterpart [NatCu]Cu-acetate, even at excess concentrations (10 µM), had no significant effect. Ex vivo biodistribution studies showed selective tumor accumulation/retention alongside expected hepatic uptake. Clear tumor visualization was achieved using μPET imaging with [64Cu]Cu-acetate (10 MBq iv). A single higher dose (65 MBq iv) effectively reduced tumor growth in a subcutaneous PC-3 xenograft mouse model, without systemic toxicity, as evidenced by stable body weight. Together, these results further support the theranostic potential of [64Cu]Cu in PCa.

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease characterized by motor neuron loss in the motor cortex, brain stem, and spinal cord. Mutations in the superoxide dismutase 1 (SOD1) gene, resulting in misfolding of its protein product, are a common cause of ALS. Currently, there is no approved ALS diagnostic tool. Here, we present the development of a PET radiotracer, [89Zr]Zr-desferoxamine (DFO)-α-miSOD1, targeting selectively misfolded SOD1 (misSOD1). Methods: DFO-α-miSOD1 was prepared by conjugating α-miSOD1 antibody with DFO and labeled with 89Zr. A longitudinal imaging study was performed to identify the optimal mouse age and time after administration of [89Zr]Zr-DFO-α-miSOD1 for the detection of misSOD1 aggregation in transgenic mice overexpressing misSOD1 and in wild-type mice. Subsets of mice were either coinjected with an excess of α-miSOD1 or imaged with deglycosylated [89Zr]Zr-DFO-α-miSOD1 to assess target specificity. The internal radiation dose for [89Zr]Zr-DFO-α-miSOD1 was estimated by extrapolating data from mouse biodistribution experiments. Results: Imaging with [89Zr]Zr-DFO-α-miSOD1 was optimal in 136-d-old transgenic mice on day 10 after administration. Significant accumulation of [89Zr]Zr-DFO-α-miSOD1 was detected in the spinal cord and cartilage of ALS transgenic mice compared with the wild-type mice (P = 0.01). The radiotracer accumulation is selective and blockable with an excess of α-miSOD1. Deglycosylated [89Zr]Zr-DFO-α-miSOD1 results in high-contrast detection of misSOD1 but is prone to aggregation. The dosimetry for [89Zr]Zr-DFO-α-miSOD1 is comparable to that for other 89Zr-based tracers currently used in humans. Conclusion: This work thus establishes that [89Zr]Zr-DFO-α-miSOD1 PET can detect misSOD1 in transgenic mice, paving the way for application in early diagnosis of ALS and therapeutic monitoring.

Prostate cancer (PCa), particularly in its metastatic form, remains a major clinical challenge due to limited diagnostic and therapeutic options. To address this, we developed a novel radiotheranostic agent, [64Cu]Cu-NOTA-TP-PSMA, by conjugating a prostate-specific membrane antigen (PSMA) ligand to a 64Cu-radiolabeled terpyridine-platinum (TP) compound previously shown to exert selective cytotoxicity against cancer cells. In this study, the biological performance of [64Cu]Cu-NOTA-TP-PSMA was compared with the monomeric analogs [64Cu]Cu-NOTA-PSMA and [64Cu]Cu-NOTA-TP through in vitro studies in PSMA-positive LNCaP prostate cancer cells and non-malignant HEK-293 cells. [64Cu]Cu-NOTA-TP-PSMA showed high stability, PSMA binding affinity and exhibited substantially enhanced uptake, internalization, retention, and nuclear localization in LNCaP cells relative to the monomers, whereas uptake and nuclear accumulation in HEK-293 cells were negligible. Cytotoxicity assays further demonstrated potent and selective activity in LNCaP cells, with EC50 values in the low nanomolar range, and minimal toxicity in HEK-293 cells. Collectively, these results identify [64Cu]Cu-NOTA-TP-PSMA as a promising radiotheranostic agent, warranting further in vivo evaluation for prostate cancer imaging and targeted radiotherapy.

The tumour sink effect is a phenomenon whereby the sequestration of a radiopharmaceutical in cancer lesions leads to decreased activity concentration in the blood stream and organs. The aim of this sub-analysis of the prospective 3TMPO study (NCT04000776) was to investigate the tumour sink effect on prostate-specific membrane antigen (PSMA) PET imaging in a population of patients with metastatic castration-resistant prostate cancer (mCRPC). Ninety-seven participants underwent 68Ga-PSMA-617 PET/CT imaging. The activity concentration in the kidney, parotid, spleen, liver and blood was expressed as a percentage of injected activity per cubic centimetre (

Increased adipose tissue (AT) dietary fatty acids (DFA) trapping limits fatty acid exposure to lean organs in the face of elevated postprandial nonesterified fatty acid (NEFA) flux from excess AT intracellular lipolysis in prediabetes. We hypothesized that pharmacological inhibition of postprandial AT intracellular lipolysis using short-acting nicotinic acid (NA) would increase AT DFA trapping and limit AT NEFA spillover to lean organs in subjects with prediabetes. Twenty subjects with impaired glucose tolerance and 19 individuals with normal glucose tolerance underwent four postprandial studies with positron emission tomography/computed tomography with radio-labeled fatty acid tracers and stable isotopic palmitate tracers. Over the 6-h postprandial period, NA increased AT DFA partitioning with reciprocal reduction in liver and in muscle. NA also robustly reduced cardiac and liver total (DFA + NEFA) postprandial fatty acid uptake. Short-acting NA administered postprandially thus enhances AT DFA trapping and markedly reduces postprandial hepatic and cardiac fatty acid uptake. (clinicaltrials.gov NCT02808182).

BackgroundTelehomecare monitoring (TM) in patients with cancer is a complex intervention. Research shows variations in the benefits and challenges TM brings to equitable access to care, the therapeutic relationship, self-management, and practice transformation. Further investigation into these variations factors will improve implementation processes and produce effective outcomes. ObjectiveThis study aims to concurrently analyze implementation and evaluate the effectiveness of TM for patients receiving anticancer oral therapy. The objectives are to (1) contextualize how and why TM is implemented according to (a) site characteristics, (b) team characteristics, and (c) characteristics of patients receiving anticancer oral therapy; (2) assess TM effectiveness for recording electronic patient-reported outcome measures (ePROMs) and patient-reported experience measures (ePREMs) according to the site, implementation process, and patient characteristics; (3) describe the acceptability and feasibility of TM from the perspectives of the people directly or indirectly involved and provide evidence-based actionable guidance in anticipation of provincewide implementation. MethodsThis type II hybrid effectiveness-implementation study uses a concurrent mixed methods design. Evaluability assessment is integrated into an emerging practice in 3 participating sites to enable the evaluation of implementation strategies on TM clinical outcomes. Quantitative data for ePROMs and ePREMs will be collected using validated oncology questionnaire. Descriptive statistics and repeated measures using multiple linear mixed models and generalized estimating equations analyses will be undertaken alongside interpretive descriptive coding of qualitative data. Qualitative data will be gathered from key informants guided by the RE-AIM (reach, efficacy, adoption, implementation, maintenance) framework and its extension, PRISM (practical robust implementation and sustainability model). The concurrent approach allows results at multiple stages of this study to be integrated iteratively. The methodological choice aims to provide real-world data that are rigorous, rapidly usable in practice, and transferable to other settings. ResultsQuestionnaires were pretested and the technological platform was codeveloped with members of the cancer care team and patients. Preparatory work was carried out to configure the TM platform and activate coordinating mechanisms between members of the cancer care team, patients, information technology experts, and the research team. A steering committee with 3 working groups was established to oversee the technological, clinical, and evaluation aspects of this study. Recruitment of patients for ePROMs started in February 2024, and data collection is expected to continue until March 2025. Interviews with members of the cancer care team began in November 2024. Full analysis should be completed by September 2025. ConclusionsThis study will clarify how, why, for whom, and under what conditions TM can complement current care models. Our evaluability assessment will help to address implementation complexities and better understand intervention-to-practice operationalization so that implementation might be adapted to contextual factors without potentially harmful or inequitable impacts on patients. International Registered Report Identifier (IRRID)DERR1-10.2196/63099

Clinicopathological studies of Alzheimer’s disease (AD) have demonstrated that synaptic or neuronal loss and clinical cognitive decline do not reliably correlate with fibrillar amyloid burden. We created a transgenic mouse model overexpressing Dutch (E693Q) mutant human amyloid precursor protein ( APP ) driven by the pan-neuronal Thy1 promoter. Accumulation of APP carboxyl-terminal fragments was observed in the brains of these mice, which develop an impaired learning phenotype directly proportional to brain oAβ levels. Male and female TgAPP E693Q mice and wildtype controls were compared using learning behavioral studies, immunocytochemistry, transmission electron microscopy, electrophysiology, protofibril-specific assays, and single cell RNA sequencing. Brain levels of nonfibrillar oAβ in Dutch mice were shown to increase aging-dependently using A11 immunocytochemistry and FITC-cyclic peptide (FITC-CP-2) microscopy. Two assays excluded the presence of protofibrils. Electrophysiological characterization of hippocampal synapses in Dutch and wildtype mice at ∼7 and ∼11 months revealed no change in basal excitatory transmission, consistent with normal density and morphology of mGluR2/3+ synapses in hippocampal CA1 of the same mice. One exception was increased postsynaptic density in non-perforated mGluR-2/3+ synapses in the Dutch mice. Functional characterization of the presynaptic terminal showed abnormalities in post-tetanic potentiation, synaptic fatigue, and synaptic replenishment after depletion in Dutch mice. Single cell RNA-seq to elucidate cell-type specific transcriptional responses to oAβ revealed altered transcriptional profiles in multiple cell types. Unexpectedly, no obvious differences existed between profiles of microglia from Dutch compared to those from wildtype mice. Excitatory neurons showed the most altered profile which was associated with ‘protein translation’ and ‘oxidative phosphorylation’. Ultrastructural analysis of presynaptic mitochondria at excitatory synapses revealed fewer mitochondria in the presynaptic terminals of Dutch mice. The profound learning behavior deficits in Dutch mice are associated with presynaptic functional deficits and mitochondrial abnormalities in excitatory neurons of the hippocampus. Nonfibrillar oAβ deposits were revealed by co-localization of A11 immunoreactivity with FITC-CP-2 microscopy. Mice accumulating only oAβ may be especially useful for further characterization of the oligomer-specific cyclic azaglycine PET tracer Lys ( 64 Cu/NOTA) 1 ]-CP-7 that shows robust PET signal from 44-day-old presymptomatic 5xFAD mice [Habashi, M. et al. Proc. Natl. Acad. Sci. U.S.A . 2022].

APP E693Q transgenic mice develop aging-related learning deficits and accumulate endogenously generated nonfibrillar aggregates of Aβ (NFA-Aβ) and APP α-carboxy terminal fragments. The APP E693Q mutation disrupts amyloid fibril formation, and no plaques develop in these mice. In the current study, the aging-related accumulation of NFA-Aβ in APP E693Q mice was revealed by A11 immunohistochemistry and NFA-Aβ-detecting cyclic D,L-α-peptide-FITC microscopy. The presynaptic termini of APP E693Q mice developed aging-related physiological abnormalities in post-tetanic potentiation, synaptic fatigue, and synaptic vesicle replenishment. Single-cell RNA sequencing showed that excitatory neurons exhibited the most altered transcriptomic profile, especially involving "protein translation" and "oxidative phosphorylation". Direct measurements of electron transport chain catalysis revealed reduction in mitochondrial complex I activity in Dutch mice. Microglial transcript analysis revealed no evidence of inflammation. The depletion or neutralization of both fibrillar and NFA-Aβ may be needed for complete elimination of Aβ toxicity. Teaser:APP E693Q "NFA-Aβ only" mice reveal clinically relevant mechanisms despite the absence of detectable inflammation.

In non-insulin-dependent, type 2, diabetes mellitus (T2D), glucose metabolism is compromised, and the heart loses its metabolic flexibility. The Zucker Diabetic Fatty rat (ZDF) model, which replicates the pathophysiology of T2D in patients, shows that as T2D progresses so does heart failure. Heart ketone metabolism seems to play a role in mitigating the heart failure process. This study assesses ketone metabolism in a ZDF heart failure model using cardiac PET imaging. Six lean ZDF rats (CTRL) and six diabetic obese ZDF rats (T2D) were evaluated for coronary flow reserve (CFR) using [13N]ammonia ([13N]NH3) cardiac PET. In addition, rats were evaluated with [11C]acetoacetate ([11C]AcAc) PET during rest and stress conditions to assess ketone metabolism, both at baseline and under an acute exogenous ketone ester oral supplementation. Blood chemistry, cardiac function and hemodynamic parameters were also evaluated under these conditions. CFR was impaired in the T2D model (CTRL: 1.8 ± 0.5; T2D: 1.4 ± 0.2, p < 0.05) suggesting the development of heart failure in the T2D model. Blood ketones increased more than 2-fold after supplementation. The [11C]AcAc heart ketone uptake values with and without ketone supplementation were similar for the CTRL group, and these values were higher than for T2D rats. For the T2D group, the uptake decreased by 20