We combined multimodal imaging (bioluminescence, X-ray computed tomography, and PET), tomographic reconstruction of bioluminescent sources, and two unique, complementary models to evaluate three previously synthesized PET radiotracers thought to target pancreatic beta cells. The three radiotracers {[(18)F]fluoropropyl-(+)-dihydrotetrabenazine ([(18)F]FP-DTBZ), [(18)F](+)-2-oxiranyl-3-isobutyl-9-(3-fluoropropoxy)-10-methoxy-2,3,4,6,7,11b-hexahydro-1H-pyrido[2,1-a]isoquinoline ((18)F-AV-266), and (2S,3R,11bR)-9-(3-fluoropropoxy)-2-(hydroxymethyl)-3-isobutyl-10-methoxy-2,3,4,6,7,11b-hexahydro-1H-pyrido[2,1-a]isoquinolin-2-ol ((18)F-AV-300)} bind vesicular monoamine transporter 2. Tomographic reconstruction of the bioluminescent signal in mice expressing luciferase only in pancreatic beta cells was used to delineate the pancreas and was coregistered with PET and X-ray computed tomography images. This strategy enabled unambiguous identification of the pancreas on PET images, permitting accurate quantification of the pancreatic PET signal. We show here that, after conditional, specific, and rapid mouse beta-cell ablation, beta-cell loss was detected by bioluminescence imaging but not by PET imaging, given that the pancreatic signal provided by three PET radiotracers was not altered. To determine whether these ligands bound human beta cells in vivo, we imaged mice transplanted with luciferase-expressing human islets. The human islets were imaged by bioluminescence but not with the PET ligands, indicating that these vesicular monoamine transporter 2-directed ligands did not specifically bind beta cells. These data demonstrate the utility of coregistered multimodal imaging as a platform for evaluation and validation of candidate ligands for imaging islets.
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http://dx.doi.org/10.1073/pnas.1109480108 | DOI Listing |
ChemMedChem
December 2024
University of Ljubljana, Faculty of Pharmacy, Askerceva cesta 7, 1000, Ljubljana, SLOVENIA.
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December 2024
China Pharmaceutical University, State Key Laboratory of Natural Medicines, CHINA.
The activation of the STING-mediated signaling pathway leads to the secretion of type I interferon (IFN) and the activation of tumor-specific T cells. STING, a pattern recognition receptor located on the endoplasmic reticulum membrane of immune cells, binds with endogenous cyclic dinucleotides. STING undergoes phosphorylation, triggering the STING-TBK1-IRF3 pathway and NF-κB pathway, resulting in the release of IFN-β and other pro-inflammatory cytokines, ultimately enhancing the activation of tumor-specific T cells.
View Article and Find Full Text PDFElife
December 2024
Arthritis and Tissue Degeneration Program and David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, United States.
The IncRNA was initially believed to be dispensable for physiology due to the lack of observable phenotypes in knockout (KO) mice. However, our study challenges this conclusion. We found that both KO and conditional KO mice in the osteoblast lineage exhibit significant osteoporosis.
View Article and Find Full Text PDFCefiderocol (FDC), a siderophore-cephalosporin conjugate, is the newest option for treating infection with carbapenem-resistant gram-negative bacteria. We identified a novel mechanism contributing to decreased FDC susceptibility in Klebsiella pneumoniae clinical isolates. The mechanism involves 2 coresident plasmids: pKpQIL, carrying variants of bla carbapenemase gene, and pKPN, carrying the ferric citrate transport (FEC) system.
View Article and Find Full Text PDFBioconjug Chem
December 2024
State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
Peptides have been extensively studied in nanomedicine with great bioactivity and biocompatibility; however, their poor cell-membrane-penetrating properties and nonselectivity greatly limit their clinical applications. In this study, tumor-targeting therapy was achieved by modifying our previously developed efficient peptide vector with the cancer-targeting peptide RGD, enabling it to specifically target tumor cells with a high expression of RGD-binding receptors. B-cell lymphoma-2 antisense oligonucleotides were selected as the target model to validate the effectiveness of the delivery carriers.
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