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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Another generator of increasing importance is 68Ge/68Ga-system where 68Ge, with a half-life of 271 days, produces a short-lived positron emitter, 68Ga, with a half-life of 68 minutes. This is produced as an ion (+3) that can be rapidly labelled, using a chelating agent such as DOTA, to small receptor-binding peptides, for example, 68Ga-DOTATOC. Due to the long half-life of the mother, the generator can be operated for up to two years and can be milked every fifth hour. One problem of such a long-lived generator is keeping it sterile, and that the ion-exchange material is exposed to high radiation doses that may reduce the elusion efficiency and the quality of the product.
Synthesis of Bioactive Peptides for Pharmaceutical Applications
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Jaison Jeevanandam, Ashish Kumar Solanki, Shailza Sharma, Prabir Kumar Kulabhusan, Sapna Pahil, Michael K. Danquah
IEX approach is reported to be extensively useful for biopeptide separation, since HPLC that can retain both basic and acidic peptide were introduced. Anion-exchange and cation-exchange HPLC, are employed for peptide separation as negative or positive charged solutes are retained by the respective ion-exchange modes. The charge distribution on the peptide surface regulates the charged group interaction with stationary phase surface. Packaging by exchange of anions commonly consists of primary, secondary, and quaternary amine groups that are linked to a support via absorption or covalent bonds. These packaging with positive charges will interact with peptide residues and α-carboxyl group in C-terminal with negative charge. Likewise, packings with cation-exchange property mostly contain sulfonate or carboxyl groups that are linked with the support matrix. These packings with negative charges will interact with the basic residues and α-amino group in N-terminal with the positive charge (Allen, 1981). Common materials used for ion exchange have been listed in Table 6.4.
Principles of Radioiodination and Iodine-Labeled Tracers in Biomedical Investigation †
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Mrinal K. Dewanjee, Shyam A. Rao
In ion-exchange chromatography, mixtures of free radiohalide from labeled compounds are separated by virtue of their difference in sign and magnitude of ionic charge. Ion-exchange materials are insoluble polymeric substances containing exchangeable ionic groups as part of their structure. They are available in a number of particle or mesh sizes for use in column or thin-layer chromatography techniques. Commercially available anion-exchange resins include resins with quaternary ammonium groups as functional groups with exchangeable counter ions of chloride (Dowex® 1, Amberlite® 400), cellulose derivatives (aminoethyl [AE] cellulose, dieth-ylaminoethyl [DEAE] cellulose, triethylaminoethyl [TEAE] cellulose, guanidoethyl [GE] cellulose, and epichlorohydrin triethanolamine [ECTEOLA] cellulose), and dex-tran derivatives (DEAE-Sephadex®).
A cost-effectiveness analysis of patiromer for the treatment of hyperkalemia in chronic kidney disease patients with and without heart failure in Spain
Published in Journal of Medical Economics, 2022
José Ramón González-Juanatey, Álvaro González-Franco, Patricia de Sequera, Marta Valls, Antonio Ramirez de Arellano, Elisenda Pomares, Diana Nieves
Over the past decades, ion exchange resins have been the most commonly used treatment to address HK, but they are associated with several drawbacks, such as safety-related contraindications due to serious gastrointestinal adverse events, risk of hypokalaemia, poor tolerability that can lead to low adherence to treatment, etc.5–7. Recent Spanish real-world data reported that only 36.8% of the patients were adherent to the treatment in the first year and 17.5% in the third year7. Patiromer is a sodium-free, cation exchange polymer that is not absorbed and is able to bind free potassium in the lumen of the gastrointestinal tract, thereby reducing its absorption6. In the OPAL-HK study, patiromer demonstrated the reduction of serum potassium levels and prevent the recurrence of HK; and, consequently, patiromer allowed to maintain RAASi optimal doses8. Patiromer has significantly changed the management of CKD by offering a solution for the maintenance of normokalemia in patients treated with RAASi.
Mercury(II) decontamination using a newly synthesized poly(acrylonitrile-acrylic acid)/ammonium molybdophosphate composite exchanger
Published in Toxin Reviews, 2022
Adel A. El-Zahhar, Abubakr M. Idris
Certain ion exchange materials were studied for metal ion removal from aqueous solutions. In particular, organic ion exchangers feature high capacity, chemically stability leading to ease of regeneration, whereas inorganic exchange materials feature thermal stability and low swelling. Composite or hybrid materials (organic and inorganic compounds) gather the potential of both organic and inorganic exchangers for metal ion removal (Bushra et al. 2012). Exceptionally, polymeric composites characterize a further collection of advantages such as the inclusion of specific functional groups, for example, –H, –NH2, –CONH2, and –COOH, which significantly improve metal ion removal efficiency. Polymeric composites also characterize granular properties that facilitate the separation of adsorbents from solutions. Moreover, polymeric composites demonstrate high adsorption capacity, allowing for feasible regeneration and reusability (Baimenov et al.2020).
Crosslinking hyaluronic acid soft-tissue fillers: current status and perspectives from an industrial point of view
Published in Expert Review of Medical Devices, 2021
Jimmy Faivre, Amos I. Pigweh, Julien Iehl, Pauline Maffert, Peter Goekjian, François Bourdon
Once the chemical modification of HA chains has occurred, the next step involves the purification of the resulting 3D network. Information about this step is often confidential and specific to each manufacturer. It is nevertheless of paramount importance to guarantee product safety. Dialysis remains the gold standard technique to purify HA gels with the use of a semipermeable membrane to selectively separate unwanted molecules such as crosslinker traces [41]. Another benefit of the dialysis is regulation of the pH of the hydrogel matrix and the opportunity for ion exchange to homogenize the ionic strength to obtain isotonic formulations suitable for injection. The disadvantages of dialysis are its long duration and the large volume of aqueous solution required for the bath where the gel contained in the membrane is immersed due to the slow diffusion of solutes within the gel network. Precipitation of the materials with organic solvents may be carried out and followed by repetitive washing, generally on laboratory scale, to remove unreacted crosslinking reagents. For instance, PEGDE-crosslinked HA gels might be washed with acetonitrile instead of water to limit excessive gel swelling as PEGDE-crosslinked gels tend to swell more than BDDE-crosslinked gels [23].