A p-[18F]Fluoroethoxyphenyl Bicyclic Nucleoside Analogue as a Potential Positron Emission Tomography Imaging Agent for Varicella-Zoster Virus Thymidine Kinase Gene Expression

Synthesis of Dicarboxylic Acids Comprising an Ether Linkage and Cyclic Skeleton and Its Further Application for High-Performance Aluminum Electrolyte Capacitors

Aluminum electrolytic capacitors are essential components in all electronic devices, and it is known that their longevity depends on the performance of their electrolytes. We synthesized dicarboxylic acids having ether bonds showing the good solubility in ethylene glycol as a solvent and simultaneously developed a complete halogen removal method, which is strictly prohibited in capacitors. Moreover, the incorporation of bulky α-substituents and cyclic structures dramatically improved their heat resistance and can withstand high voltage, i.e., 764 V.

Hetero-bimetallic cooperative catalysis for the synthesis of heteroarenes

Review covering the synthesis of 5- and 6-membered as well as condensed heteroarenes, focussing on the combinations in cooperative catalytic systems in strategies used to achieve selectivity and also highlights the mode of action for the cooperative catalysis leading to the synthesis of commercially and biologically relevant heteroarenes.

Synthesis and Evaluation of a 18F-Labeled Triazinediamine Analogue for Imaging Mutant IDH1 Expression in Gliomas by PET

Mutations in the isocitrate dehydrogenase gene 1 (IDH1) are common in gliomas. Studies suggest that IDH1 mutations are early events in glioma formation and are important drivers of malignant progression. Herein, we report the synthesis and evaluation of a ¹⁸F-labeled triazinediamine analogue, [¹⁸F]1, as a candidate radiotracer for noninvasive imaging of IDH1 mutations in gliomas by positron emission tomography (PET). In vitro studies revealed good binding inhibition potency and binding affinity for [¹⁸F]1 in IDH1 mutant glioma cell lines, with a half-maximal inhibitory concentration value (IC₅₀) of 54 nM and an equilibrium dissociation constant (K_d) of 40 nM. In vivo studies using mutant IDH1 glioma xenografts showed good tumor uptake of [¹⁸F]1 and specific inhibition by the unlabeled 1, but also elevated radioactivity uptake in the bone, suggesting significant defluorination. The results support further optimization of the triazinediamine scaffold to develop a more stable and potent ¹⁸F-labeled analogue for PET imaging of IDH1 mutations in gliomas.

A bi-stable Pt(ii) based molecular turnstile

Playing with the competition between H- and coordination-bonds, a bi-stable unsymmetrical organometallic turnstile may be switched between two closed states.

Preliminary validation of varicella zoster virus thymidine kinase as a novel reporter gene for PET

INTRODUCTION

Imaging of gene expression with positron emission tomography (PET) has emerged as a powerful tool for biomedical research during the last decade. The prototypical herpes simplex virus type 1 thymidine kinase (HSV1-TK) PET reporter gene (PRG) is widely used and many other PRGs have also been validated. We investigated varicella zoster virus thymidine kinase (VZV-tk) as new PRG with radiolabeled bicyclic nucleoside analogues (BCNAs) as PET tracers.

METHODS

The uptake and washout of four different radiolabeled BCNAs was evaluated in cells expressing VZV-tk after lentiviral vector (LV) transduction and in control cells. Metabolism of the tracers was assayed by high pressure liquid chromatography (HPLC). Mice bearing VZV-TK expressing xenografts were imaged with PET.

RESULTS

High uptake in VZV-tk expressing cells was seen for 3 of the 4 tracers tested. The uptake of the tracers could be blocked by the presence of excess thymidine in the incubation solution. Cellular retention was variable, with one tracer showing an acceptable half-life of ~1 hour. The amount of intracellular tracer correlated with the titer of LV used to transduce the cells. VZV-TK dependent conversion into metabolites was shown by HPLC. No specific accumulation was observed in cells expressing a fusion protein containing an HSV1-TK moiety. VZV-tk expression in xenografts resulted in a 60% increase in uptake in vivo as measured with PET.

CONCLUSIONS

We have validated the combination of VZV-tk and radiolabeled BCNAs as new PRG/PRP system. Further optimization of the PRPs and the PRG are warranted to increase the signal.