Chromatographic separation of silver-111 from neutron-irradiated palladium target: toward direct labeling of radiotracers.

BACKGROUND: Silver-111 is a promising ß--emitting radioisotope with ideal characteristics for targeted radionuclide therapy and associated single photon emission tomography imaging. Its decay properties closely resemble the clinically established lutetium-177, making it an attractive candidate for therapeutic applications. In addition, the clinical value of silver-111 is further enhanced by the existence of the positron-emitting counterpart silver-103, thus imparting a truly theranostic potential to this element. A so-fitting matching pair could potentially overcome the current limitations associated with the forced use of chemically different isotopes as imaging surrogates of lutetium-177, leading to more accurate and efficient diagnosis and treatment. However, the use of silver-111-based radiopharmaceuticals in vivo has faced obstacles due to the challenges related to its production and radiochemical separation from the target material. To address these issues, this study aims to implement a chromatographic separation methodology for the purification of reactor-produced silver-111. The ultimate goal is to achieve a ready-to-use formulation for the direct radiolabeling of tumour-seeking biomolecules. RESULTS: A two-step sequence chromatographic process was validated for cold Ag-Pd separation and then translated to the radioactive counterpart. Silver-111 was produced via the 110Pd(n,γ)111Pd nuclear reaction on a natural palladium target and the subsequent ß--decay of palladium-111. Silver-111 was chemically separated from the metallic target via the implemented chromatographic process by using commercially available LN and TK200 resins. The effectiveness of the separations was assessed by inductively coupled plasma optical emission spectroscopy and γ-spectrometry, respectively, and the Ag+ retrieval was afforded in pure water. Recovery of silver-111 was > 90% with a radionuclidic purity > 99% and a separation factor of around 4.21·10-4. CONCLUSIONS: The developed separation method was suitable to obtain silver-111 with high molar activity in a ready-to-use water-based formulation that can be directly employed for the labeling of radiotracers. By successfully establishing a robust and efficient production and purification method for silver-111, this research paves the way for its wider application in targeted radionuclide therapy and precision imaging.

Instantaneous dental implant loading technique by fixed dentures: A retrospective cohort study.

BACKGROUND: In the context of dental prostheses, splinting multiple implants together may improve their stability. The approach may be especially favorable when performing immediate loading procedures, increasing the implant osseointegration rate, and reducing the risk of implant and prosthetic failure. The instantaneous loading technique (ILT) involves creating a metal framework to splint the implants by intraorally welding them pair-by-pair, using purposefully created abutments. OBJECTIVES: The aim of the study was to investigate the prosthetic success when using ILT to rehabilitate partially edentulous patients through immediately loaded prostheses. MATERIAL AND METHODS: Clinical records of patients treated with ILT were retrospectively assessed, and the prosthetic success rate was analyzed in terms of fractures, chipping, unscrewing, screw fracture rate, and mucositis. Furthermore, the implant success rates were evaluated by measuring marginal bone loss (MBL). RESULTS: A total of 55 patients (20 males and 35 females with a mean age of 59.8 ±9.4 years), corresponding to 66 prostheses, were included. A total of 160 implants were placed. At the last follow-up (39.6 ±28.4 months), 1 patient (1.8%; 1 prosthesis (1.5%)) showed the fracture of the prosthesis material. Peri-implantitis affected 4 implants (2.5%), and 4 more implants (2.5%) showed radiolucency, affecting 5 patients (9.1%). Two other patients (3.6%) suffered from mucositis. The implant success rate, according to the Albrektsson and Zarb criteria, was 94.4%. No implants were lost. The mean MBL values at the implant level, the prosthesis level and the patient level were 0.28 ±0.56 mm, 0.30 ±0.51 mm and 0.33 ±0.54 mm, respectively. CONCLUSIONS: The instantaneous loading technique appears to be a viable approach to rehabilitating partially edentulous patients through immediate loading.

Intraorally welded wing abutments supporting full-arch prostheses: A retrospective clinical study.

BACKGROUND: Delayed loading in the rehabilitation of edentulous patients with an implant-supported prosthesis implies a longer treatment time. It requires additional surgery to uncover the submerged implants, and this may increase patients' discomfort and morbidity. OBJECTIVES: The immediate loading-based technique described in this article involves creating a metal framework by intraorally welding the implants pair by pair, using specific wing abutments. The aim of the study was to investigate the implant-prosthetic success and complication rates of this technique when used to rehabilitate totally edentulous patients. MATERIAL AND METHODS: The clinical records of totally edentulous patients were retrospectively evaluated. The prosthetic success rate as well as technical and biological complications were analyzed. Furthermore, the implant survival and success rates were assessed by measuring marginal bone loss (MBL) at the implant, prosthesis and patient levels. RESULTS: The records of 37 patients (284 implants and 43 prostheses) were included in the study. At the last follow-up (45.5 ±33.6 months), the prosthetic success rate was 100%. Mucositis affected 4 implants (1.4%), while peri-implantitis affected 4 implants (1.4%). Meanwhile, 7 implants (2.5%) showed a lack of early osseointegration. According to the criteria of Albrektsson et al., 271 implants (95.4%) were successful. The average MBL at the implant, prosthesis and patient levels was 0.26 ±0.42 mm, 0.26 ±0.19 mm and 0.26 ±0.18 mm, respectively. CONCLUSIONS: The technique described in this article seems to be a viable approach to the rehabilitation of totally edentulous patients through immediate loading. However, these results should be confirmed by appropriately designed prospective and comparative clinical studies.

Overriding ortho selectivity by template assisted meta-C-H activation of benzophenones.

An orthogonal selectivity for distal meta-C-H activation of benzophenone is acheived by overriding the inherent proximal ortho-selectivity through a template assisted metalation approach. This strategy has been successfully utilized in Pd-catalyzed regioselective C-C and C-Si bond formation.

Trifluoromethylation of Allenes: An Expedient Access to α-Trifluoromethylated Enones at Room Temperature.

A silver(I) catalyzed regioselective trifluoromethylation of allenes using Langlois's salt (NaOSOCF3 ) is demonstrated. This transformation enables direct expedient access to α-trifluoromethylated acroleins, which are valuable synthons for a number of pharmaceuticals and agrochemicals containing vinyl-CF3 moieties. Versatility of this trifluoromethylation method has been established with good yield and excellent regioselectivity. Preliminary experiments and computational studies were carried out to elucidate the mechanistic insight of this protocol.

Stereoselective preparation of key intermediates for the synthesis of iso-, neuro- and phyto-prostane family members: inaugural asymmetric synthesis of 17-E2c-dihomo- and 17-F2c-dihomo-isoprostanes.

A practical methodology for the synthesis of key intermediates for isoprostane, neuroprostane and dihomo-isoprostane preparation has been described. The key strategy involved a three stage C-12 stereocenter inversion of the configuration of a Corey lactone, commercially available in an enantiopure form. The key intermediate was then used to prepare 17-E2c-dihomo-isoprostane and 17-F2c-dihomo-isoprostane.

A unified stereodivergent strategy for prostaglandin and isoprostanoid synthesis.

Acetoxyfulvene surrended to asymmetric Diels-Alder cycloaddition, paving the way to the development of a unified strategy for the stereodivergent synthesis of both prostaglandins and isoprostanoids. In fact, the cycloadduct was subsequently converted to a common intermediate, which through two different stereoselective pathways afforded the two lactones 1 and 2, which are key building blocks in the synthesis of prostaglandins and isoprostanoids, respectively.

Excitation function for deuteron induced nuclear reactions on natural ytterbium for production of high specific activity 177g Lu in no-carrier-added form for metabolic radiotherapy.

Deuteron-induced nuclear reactions for generation of no-carrier-added Lu radionuclides were investigated using the stacked-foil activation technique on natural Yb targets at energies up to E(d)=18.18 MeV. Excitation functions of the reactions (nat)Yb(d,xn)(169,170,171,172,173,174g,174m,176m,177g)Lu and (nat)Yb(d,pxn)(169,175,177)Yb have been measured, among them three ((169)Lu, (174m)Lu and (176m)Lu) are reported for the first time. The upper limit of the contamination from the long-lived metastable level (177m)Lu was evaluated too. Thick-target yields for all investigated radionuclides are calculated.