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Abstract Background The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development. Main body This selection of highlights provides commentary on 24 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first-in-human application of novel radiopharmaceuticals. Conclusion Trends in radiochemistry and radiopharmacy are highlighted. Hot topics cover the entire scope of EJNMMI Radiopharmacy and Chemistry, demonstrating the progress in the research field in many aspects.

The human epidermal growth factor receptor 2 (HER2/neu) is overexpressed in 20–30% of breast cancers and is associated with tumor growth, angiogenesis, and development of distant metastases. Trastuzumab, an anti-HER2 monoclonal antibody, is used for the treatment of HER2 positive breast cancer and clinical efficacy of this agent is dependent on HER2 expression. Targeted PET imaging of HER2 with radiolabeled trastuzumab may be used to determine HER2 expression levels and guide therapy selection. The purpose of the current study was to evaluate a facile 89Zr-trastuzumab preparation method that can be efficiently applied for clinical grade production. Also, relative HER2 expression levels in orthotopic and metastatic breast cancer models were assessed by PET imaging using the 89Zr-trastuzumab produced by this simpler method.

The first analysis of chloride fluxes and compartmentation in a non-excised plant system is presented, examining ten ecologically pertinent conditions. The short-lived radiotracer couple 38Cl/ 39Cl was used as a Cl - tracer in intact barley ( Hordeum vulgare L. cv. Klondike) seedlings, which were cultured and investigated under four external [Cl -], from abundant (0.1 mM) to potentially toxic (100 mM). Chloride?nitrogen interactions were investigated by varying N source (NO 3 - or NH 4 +) and strength (0.1 or 10 mM), in order to examine, at the subcellular compartmentation level, the antagonism, previously documented at the influx level, between Cl - and NO 3 -, and the potential role of Cl - as a counterion for NH 4 + under conditions in which cytosolic [NH 4 +] is excessive. Cytosolic [Cl -] increased with external [Cl -] from 6 mM to 360 mM. Cl - influx, fluxes to vacuole and shoot, and, in particular, efflux to the external medium, also increased along this gradient. Efflux reached 90% of influx at the highest external [Cl -]. Half-times of cytosolic Cl - exchange decreased between high-affinity and low-affinity influx conditions. The relationship between cytosolic [Cl -] and shoot flux indicated the presence of a saturable low-affinity transport system (?SLATS?) responsible for xylem loading of Cl -. N source strongly influenced Cl - flux to the vacuole, and moderately influenced Cl - influx and shoot flux, whereas efflux and half-time were insensitive to N source. Cytosolic pool sizes were not strongly or consistently influenced by N source, indicating the low potential for Cl - to act as a counterion to hyperaccumulating NH 4 +. We discuss our results in relation to salinity responses in cereals. [ABSTRACT FROM AUTHOR]

Vitamin H (biotin) is delivered to the fetus transplacentally by an active biotin-transport mechanism and is critical for fetal development. Our objective was to develop a comprehensive MRI technique for mapping biotin transporter activity in the murine placenta. Visualization of transporter activity can employ MRI's unique T2*-dependent signal 'off-switch', which is triggered by transporter mediated aggregation of biotinylated contrast agent (b-BSA-Gd-DTPA). MRI data were collected from pregnant mice after administration of b-BSA-Gd-DTPA and analyzed using a new sub-voxel biophysical signal model. Validation experiments included competition with native biotin, comparative tests using PET, histology, and ICPMS. MRI signal was governed by binding, aggregation, and clearance of biotin (confirmed by histology). Signal dynamics reflected the placenta's perfusion pattern modulated by biotin transporter activity and trophoblast mediated retention, and were in congruence with a three-compartment sub-voxel model. Pre-saturation of the transporters with free biotin suppressed b-BSA-Gd-DTPA uptake. The results were confirmed by PET, histology and ICPMS. The presented MRI-based platform allows to track activity of essential molecular transporters in the placenta, reflecting a transporter-mediated uptake, followed by retention and aggregation, and recycling associated with the large b-BSA-Gd-DTPA conjugate. The presented DCE-MRI technique can furthermore be used to map and characterize microstructural compartmentation and transporter activity without exposing the fetus to contrast media. [ABSTRACT FROM AUTHOR]