Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH2 )m ]n (n=1-4; m=3-7).

The Te⋅⋅⋅Te secondary bonding interactions (SBIs) in solid cyclic telluroethers were explored by preparing and structurally characterizing a series of [Te(CH2 )m ]n (n=1-4; m=3-7) species. The SBIs in 1,7-Te2 (CH2 )10 , 1,8-Te2 (CH2 )12 , 1,5,9-Te3 (CH2 )9 , 1,8,15-Te3 (CH2 )18 , 1,7,13,19-Te4 (CH2 )20 , 1,8,15,22-Te4 (CH2 )24 and 1,9,17,25-Te4 (CH2 )28 lead to tubular packing of the molecules, as has been observed previously for related thio- and selenoether rings. The nature of the intermolecular interactions was explored by solid-state PBE0-D3/pob-TZVP calculations involving periodic boundary conditions. The molecular packing in 1,7,13,19-Te4 (CH2 )20 , 1,8,15,22-Te4 (CH2 )24 and 1,9,17,25-Te4 (CH2 )28 forms infinite shafts. The electron densities at bond critical points indicate a narrow range of Te⋅⋅⋅Te bond orders of 0.12-0.14. The formation of the shafts can be rationalized by frontier orbital overlap and charge transfer.

Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH2 )m ]n (n=1-4; m=3-7).

Invited for the cover of this issue are the groups of Risto Laitinen at University of Oulu and Wolfgang Weigand at Friedrich Schiller University Jena. The image depicts a picturesque view of the Te⋅⋅⋅Te close contacts forming infinite tubular shafts in 1,9,17,25-Te4 (CH2 )28 . The cover artwork was designed and created by Marko Rodewald. Read the full text of the article at 10.1002/chem.202002510.

Radionuclide Cisternography with [64Cu]Cu-DOTA.

Radionuclide cisternography (RNC) is a method for conducting imaging of the cerebrospinal system and can be used to identify cerebrospinal fluid leaks. So far, RNC has commonly employed radiopharmaceutical agents suitable only for single-photon emission tomography techniques, which are thus lacking in terms of image resolution and can potentially lead to false-negative results. Therefore, [64Cu]Cu-DOTA was investigated as an alternative radiopharmaceutical for RNC, employing positron emission tomography (PET) instead of single-photon emission tomography. A formulation of [64Cu]Cu-DOTA was produced according to the guidelines for good manufacturing practice. The product met the requirements of agents suitable for intrathecal application. [64Cu]Cu-DOTA was administered to a patient and compared to the approved scintigraphic RNC agent, [111In]In-DTPA. While no cerebrospinal fluid leak was detected with [111In]In-DTPA, [64Cu]Cu-DOTA RNC exhibited a posterolateral leak between the vertebral bodies C1 and C2. Thus, in this patient, PET RNC with [64Cu]Cu-DOTA was superior to RNC with [111In]In-DTPA. Since radiopharmaceuticals have a very good safety profile regarding the occurrence of adverse events, PET RNC with [64Cu]Cu-DOTA may become an attractive alternative to scintigraphic methods, and also to computed tomography or magnetic resonance imaging, which often require contrast agents, causing adverse events to occur much more frequently.

Design and practical evaluation of a shielded application system for intravenously administered radionuclide therapies.

AIM: Intravenous radionuclide therapies are gaining importance. With the increased frequency of these therapies, safe application procedures in combination with effective radiation protection are needed. We present a shielded system which can be universally used for the application of liquid radiopharmaceuticals. MATERIALS AND METHODS: The application system consists of a cuboidal box made of lead with stainless steel coating, an inner layer of polymethyl methacrylate (PMMA), a disposable line/bottle system, and a medical infusion pump. No proprietary disposable parts are used. The system was tested and validated ex-vivo, and evaluated for Lu-177 peptide receptor radionuclide and for radioligand therapies (PRRT, RLT). RESULTS: Construction of the application system was performed in accordance with the physical characteristics of the used isotopes. 10 validation procedures with 1 GBq Tc-99m-pertechnetate confirmed functionality. 38 PRRT and 13 RLT procedures were performed successfully and completely. At least 98 % of the prescribed activities were infused. No leakage of radioactivity occurred. Dose rate measurements showed that the radiation in the box is shielded completely, and that exposure arises only from the infusion line outside the box and from the patient. CONCLUSION: The presented application system for intravenous radionuclide therapies is feasible, safe, and cost-efficient. It has been shown that Lu-177-PRRT and -RLT can be performed without complications while ensuring nearly complete infusion of the prescribed radiopharmaceutical dose. Radiation exposure of the applying physician and other staff is low. The construction of the shielding box ensures complete shielding of all radionuclides currently used for radiomolecular therapies.

The Use of Ostrich Eggs for In Ovo Research: Making Preclinical Imaging Research Affordable and Available.

In ovo studies are a valuable option in preclinical research, but imaging studies are severely limited by the costs of dedicated equipment needed for small-sized eggs. We sought to verify the feasibility of using larger, ostrich, eggs (Struthio camelus) for imaging on the PET/CT scanners used for routine clinical investigations. Methods: Ostrich eggs were incubated until shortly before hatching, prepared for intravitelline venous injection of contrast medium or radiotracer, and imaged using native CT, contrast-enhanced CT, and PET/CT. Any technical adaptations that were needed to improve the outcome were noted. Results: Of the 34 eggs initially incubated, 12 became fully available for imaging of embryonal development. In ovo imaging with conventional PET/CT not only was feasible but also provided images of good quality, including on dynamic PET imaging. Conclusion: In ovo imaging with ostrich eggs and routine clinical scanners may allow broader application of this field of preclinical research, obviating costly dedicated equipment and reducing the number of animals needed for classic animal research. Further experiments are warranted to refine this novel approach, especially to reduce motion artifacts and improve monitoring of viability.

Investigations on the Ga(III) Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue.

We demonstrate a method for the isolation of EOB-DTPA (3,6,9-triaza-3,6,9-tris(carboxymethyl)-4-(ethoxybenzyl)-undecanedioic acid) from its Gd(III) complex and protocols for the preparation of its novel non-radioactive, i.e., natural Ga(III) as well as radioactive (68)Ga complex. The ligand as well as the Ga(III) complex were characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and elemental analysis. (68)Ga was obtained by a standard elution method from a (68)Ge/(68)Ga generator. Experiments to evaluate the (68)Ga-labeling efficiency of EOB-DTPA at pH 3.8-4.0 were performed. Established analysis techniques radio TLC (thin layer chromatography) and radio HPLC (high performance liquid chromatography) were used to determine the radiochemical purity of the tracer. As a first investigation of the (68)Ga tracers' lipophilicity the n-octanol/water distribution coefficient of (68)Ga species present in a pH 7.4 solution was determined by an extraction method. In vitro stability measurements of the tracer in various media at physiological pH were performed, revealing different rates of decomposition.

Low-activity 124I-PET/low-dose CT versus 99mTc-pertechnetate planar scintigraphy or 99mTc-pertechnetate single-photon emission computed tomography of the thyroid: a pilot comparison.

PURPOSE OF THE REPORT: The standard thyroid functional imaging method, 99mTc-pertechnetate (99mTc-PT) planar scintigraphy, has technical drawbacks decreasing its sensitivity in detecting nodules or anatomical pathology. 124I-PET, lacking these disadvantages and allowing simultaneous CT, may have greater sensitivity for these purposes. We performed a blinded pilot comparison of 124I-PET(/CT) versus 99mTc-PT planar scintigraphy or its cross-sectional enhancement, 99mTc-PT single-photon emission CT (SPECT), in characterizing the thyroid gland with benign disease. PATIENTS AND METHODS: Twenty-one consecutive adults with goiter underwent low-activity (1 MBq/0.027 mCi) 124I-PET/low-dose (30 mAs) CT, 99mTc-PT planar scintigraphy, and 99mTc-PT-SPECT. Endpoints included the numbers of "hot spots" with/without central photopenia and "cold spots" detected, the proportion of these lesions with morphological correlates, the mean volume and diameter of visualized nodules, and the number of cases of lobus pyramidalis or retrosternal thyroid tissue identified. RESULTS: 124I-PET detected significantly more "hot spots" with/without central photopenia (P < 0.001), significantly more nodules (P < 0.001), and more "cold spots" than did 99mTc-PT planar scintigraphy or 99mTc-PT-SPECT, including all lesions seen on the 99mTc-PT modalities. Ultrasonographic correlates were found for all nodules visualized on all 3 modalities and 92.5% of nodules seen only on 124I-PET. Nodules discernible only on 124I-PET had significantly smaller mean volume or diameter (P < 0.001) than did those visualized on 99mTc-PT planar scintigraphy or 99mTc-PT-SPECT. 124I-PET(/CT) identified significantly more patients with a lobus pyramidalis (P < 0.001) or retrosternal thyroid tissue (P < 0.05). CONCLUSIONS: 124I-PET(/CT) may provide superior imaging of benign thyroid disease compared to planar or cross-sectional 99mTc-PT scintigraphy.

Synthetic strategies to a backbone-side chain cyclic SHP-1 N-SH2 ligand containing N-functionalized alkyl phosphotyrosine.

The cyclic peptide EGLNc Psi [CON((CH(2))(3)NH)pYNleE(NHCH(2)CO)]L-NH(2) (1) was designed and synthesized according to a native interaction partner of tyrosine phosphatase SHP-1. We introduced N-aminopropyl-phosphotyrosine to enable backbone-side chain cyclization with a glutamic acid derivative as counterpart for cyclization. Different approaches have been compared to find a strategy for the generation of backbone and backbone-side chain cyclic phosphopeptides.