Positron emission tomography (PET) is a molecular diagnostic imaging technology to quantitatively visualize biological processes in vivo. For many applications, including imaging of low-tissue density targets (e.g., neuroreceptors), imaging in small animals, and evaluation of novel tracers, the injected PET tracer must be produced with high molar activity to ensure low occupancy of biological targets and avoid pharmacologic effects. Additionally, high molar activity is essential for tracers with lengthy syntheses or tracers transported to distant imaging sites. Here we show that radiosynthesis of PET tracers in microliter volumes instead of conventional milliliter volumes results in substantially increased molar activity, and we identify the most relevant variables affecting this parameter. Furthermore, using the PET tracer [ 18 F]fallypride, we illustrate that molar activity can have a significant impact on biodistribution. With full automation, microdroplet platforms could provide a means for radiochemists to routinely, conveniently, and safely produce PET tracers with high molar activity.

Edited by Xiao-Fan WangAndrogens such as testosterone and dihydrotestosterone are a critical driver of prostate cancer progression. Cancer resistance to androgen deprivation therapies ensues when tumors engage metabolic processes that produce sustained androgen levels in the tissue. However, the molecular mechanisms involved in this resistance process are unclear, and functional imaging modalities that predict impending resistance are lacking. Here, using the human LNCaP and C4-2 cell line models of prostate cancer, we show that castration treatment-sensitive prostate cancer cells that normally have an intact glucuronidation pathway that rapidly conjugates and inactivates dihydrotestosterone and thereby limits androgen signaling, become glucuronidation deficient and resistant to androgen deprivation. Mechanistically, using CRISPR/Cas9-mediated gene ablation, we found that loss of UDP glucuronosyltransferase family 2 member B15 (UGT2B15) and UGT2B17 is sufficient to restore free dihydrotestosterone, sustained androgen signaling, and development of castration resistance. Furthermore, loss of glucuronidation enzymatic activity was also detectable with a nonsteroid glucuronidation substrate. Of note, glucuronidation-incompetent cells and the resultant loss of intracellular conjugated dihydrotestosterone were detectable in vivo by 18 F-dihydrotestosterone PET. Together, these findings couple a mechanism with a functional imaging modality to identify impending castration resistance in prostate cancers.The long-standing standard treatment for advanced prostate cancer is androgen deprivation therapy by way of medical or surgical castration (1). Therapeutic responses usually occur and tumors eventually develop resistance as castration-resistant prostate cancer (CRPC) 2 (2, 3). This resistant state is frequently first heralded by a rising prostate-specific antigen (PSA), which is an androgen-responsive gene and is indicative of a reinstatement of androgen receptor (AR) stimulation (4). CRPC is also accompanied by tumors developing the metabolic capability of regenerating their own potent androgens, i.e. testosterone and/or dihydrotestosterone (DHT), from extragonadal precursor steroids (5-7). The role and requirement for extragonadal androgen synthesis in advanced prostate cancer was recently bolstered by a profound prolongation of survival in clinical trials of patients treated upfront with extragonadal androgen synthesis inhibition in addition to castration (8,9).The metabolic mechanisms that enable sustained tissue concentrations of potent androgens in CRPC that occurs alongside the absence of gonadal testosterone in circulation remain poorly understood. Furthermore, imaging for prostate cancer is very limited and mainly focused on tumor localization. There is a complete absence of functional imaging approaches that are informative of the metabolic state of the disease that provides information on tumor susceptibility to systemic therapies in the clinical standard of care.Glucuronidation is a major mechanism of androgen...

The chondrogenic differentiation of mesenchymal stem cells (MSCs) is mediated by transcription factors and small noncoding RNAs such as microRNAs (miRNAs). Each miRNA is initially transcribed as a long transcript, which matures to produce -5p and -3p strands. It is widely believed that the mature and functional miRNA from any given pre-miRNA, usually the -5p strand, is functional, while the opposing -3p strand is degraded. However, recent cartilage literature started to show functional -3p strands for a few miRNAs. This study aimed at examining both -5p and -3p strands of two key miRNAs miR-140 and miR-145, known to be involved in the chondrogenic differentiation of MSCs. The level (copy number) of both -5p and -3p strands of miR-145 and miR-140 along the time line of MSC chondrogenic differentiation was determined by polymerase chain reaction. The gene expression profiles of several genes related to MSC chondrogenesis were compared with these miRNA profiles along the same timeline. While miR-145-3p is declining in step with miR-145-5p in pellet cultures during the process, the -3p strand is only 1-2% of the total miR-145 products. In contrast, the mature -3p and -5p products of miR-140 are found to increase with near-equal molar expression throughout chondrogenic differentiation. Numerous genes are expressed by cartilage progenitor cells during development. One such target gene, Sox9, is a regulatory target of the dominant miR-145-5p, consistent with the data. Further experimental validations are warranted to confirm that ACAN, FOXO1, and RUNX3 as direct targets of miR-145-5p in the context of MSC chondrogenesis. Similarly, TRSP1 and ACAN are worth further validation as direct targets of miR-145-3p. For miR-140, SOX4 shall be further validated as a direct target of miR-140-5p, while KLF4, PTHLH, and WNT5A can be validated as direct targets of miR-140-3p.

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Until now, there is no systematic information on the role of endothelial dysfunction in the mechanisms of disorders of blood coagulation potential and microcirculation in different organs and tissues in preeclampsia.Objective: Our aim was to extend the existing principles of diagnosis of pre-eclampsia by establishing the role of endothelial dysfunction in the mechanisms of blood coagulation potential violations. Methods: A prospective comparative study was performed. Condition of coagulation processes studied by conventional techniques, parameters of a functional endothelium (nitric oxide metabolites, endothelin 1, thrombospondin, thrombomodulin and intercellular adhesion molecules in blood plasma) — by ELISA.Results: The study group included 55 patients with moderate preeclampsia and 49 pregnant women with severe pre-eclampsia, in the control group — 40 women with physiological pregnancy. In patients with pre-eclampsia moderate observed increase in plasma endothelin-1 (p 0.001), thrombospondin (p 0.001), intercellular adhesion molecules (p 0.001) while reducing the level of nitrogen oxide (p 0.001), increase in time of fibrinolysis (p 0.050) and decreased international normalized ratio (p 0.050) compared with the control group. With increasing severity of preeclampsia the researchers detected in blood plasma of patients a progressive increase in endothelin 1 (p1 0.020), thrombospondin (p1 0.001), intercellular adhesion molecules (p1 0.001) and decrease of nitric oxide metabolites (p1 0.001) and thrombomodulin (p1 0.001); the last combined with the activation of procoagulant hemostasis.Conclusion: There is a pathogenetic relationship between the development of endothelial dysfunction, impaired blood coagulation potential and the severity of clinical signs of preeclampsia. To widen the number of existing techniques to diagnose the severity of pre-eclampsia we recommende to mesure endothelin 1, thrombomodulin, thrombospondin, intercellular adhesion molecules and nitric oxide metabolites in the blood plasma, and use traditional indicators to assess the hemostatic system.