Synthesis and evaluation of radioiodinated estrogens for diagnosis and therapy of male urogenital tumours.

The preparation of 24 estrogens, their estrogen receptor (ER) affinity and studies of radioiodinated estrogen binding to ER-positive male bladder tumor cells (HTB9) are described. The estrogens with the highest affinity were selected using fluorescence anisotropy assays. A 2,2,2-trifluoroethyl group at the 11ß-position caused particularly promising affinity. (Radio)iodination was performed on the 17α-vinyl group. Binding studies on HTB9 cells revealed picomolar affinities of radioconjugates 19 and 31, indicating promising ability for targeting of urogenital tumors.

From Bench to Bedside: Patient-Oriented Radiopharmaceutical Development in Nuclear Medicine Based on the Example of [89Zr]Zr-PSMA-DFO.

The interdisciplinary possibilities inherent in nuclear medicine offer an opportunity for the patient-centered development of radioactive pharmaceuticals based on specific research questions. This approach provides radiopharmaceutical manufacturers with a robust scientific foundation on which to navigate the regulatory requirements for drug approval laid down by the law. A vivid illustration of this interdisciplinary cooperation has been the development of a Zr-89-labeled PSMA ligand where reliable results have been obtained across various domains, including chemistry, radiochemistry, biochemistry, and preclinical research. This comprehensive process extended to feasibility studies conducted with carefully selected patients from a single nuclear medicine clinic. The approach demonstrates how far close collaboration between different disciplines within nuclear medicine can further the move towards patient-oriented radiopharmaceutical treatments while simultaneously meeting regulatory demands. With such a strategy, innovative radiopharmaceutical solutions can be brought to the market more swiftly and efficiently, in line with the needs of patients.

Diels-Alder cycloadditions on synthetic RNA in mammalian cells.

Inverse electron demand Diels-Alder cycloadditions are extremely useful tools for orthogonal labeling of biomolecules such as proteins or small molecules in a cellular context. In-cell labeling of dienophile-modified RNA oligonucleotides using Diels-Alder cycloaddition reactions has not been demonstrated before. In this study we report site-specific labeling of RNA oligonucleotides modified with norbornene derivatives at a predefined sequence position within an RNA sequence in vitro and in mammalian cells using various tetrazine-fluorophore conjugates. The approach could in future be used as a chemical tool for the detection and investigation of RNA functions in cells minimizing the presumed distortion of RNA functions by a large chemical reporter group such as a fluorophore.

Cryopreservation of human ovarian tissue: effect of spontaneous and initiated ice formation.

This investigation compared conventional freezing of human ovarian tissue using either spontaneous or initiated ('seeded') ice formation. Biopsies of ovarian tissue were obtained from women with indications for chemotherapy or radiotherapy. Small pieces of experimental tissue were randomly distributed into three groups that were then subjected to different treatments prior to culture in vitro for 16 days: the control group, no treatment, cultured immediately after biopsy (group 1); cryopreservation/thawing with spontaneous ice formation (group 2); and cryopreservation/thawing with initiated ice formation (group 3). Follicle viability and hormonal activity were then evaluated. There was no significant difference between groups regarding the concentration of oestradiol 17-beta in the culture supernatant, whereas progesterone concentration was significantly (P < 0.05) higher in group 1 compared with group 2 or 3. There was a significant (P < 0.05) difference in primordial and primary follicle density between all of the groups (group 1 having the highest and group 2 having the lowest) and group 2 had significantly (P < 0.05) fewer normal grade follicles than the other two groups. For optimal cryopreservation of human ovarian tissue, the protocol of conventional freezing should therefore include a step of initiated ice formation.

Effective method for in-vitro culture of cryopreserved human ovarian tissue.

It is widely accepted that it is possible to successfully cryopreserve human ovarian tissue by direct plunging into liquid nitrogen using permeable cryoprotectants only, without disaccharides. This study aimed to search for and test a new method for in-vitro culture of vitrified tissue. Ovarian biopsies were obtained during operative laparoscopy. Pieces of ovarian tissue were vitrified and warmed. After warming, tissue pieces were randomly distributed into three groups for further culture: in 2 ml of culture medium which was regularly renewed (group 1), in 30 ml of culture medium without agitation (group 2) and in 30 ml of culture medium with agitation (group 3). During the 2-week and 6-week culture, the growth of follicles within the vitrified-warmed ovarian tissue pieces was investigated. After 2 weeks of culture, mean numbers of non-degenerated follicles per mm(2) of tissue were 1.5, 1.7 and 4.5 for groups 1, 2 and 3 respectively (groups 1 and 2 versus group 3, P < 0.05). Agitation during culture of ovarian tissue is beneficial, and can be used as a prognostic tool for future warming and autotransplantation of ovarian tissue.