Review

The chalcogen elements oxygen, sulfur, and selenium are essential constituents of side chain functions of natural amino acids. Conversely, no structural and biological function has been discovered so far for the heavier and more metallic tellurium element. In the methionine series, only the sulfur-containing methionine is a proteinogenic amino acid, while selenomethionine and telluromethionine are natural amino acids that are incorporated into proteins most probably because of the tolerance of the methionyl-tRNA synthetase; so far, methoxinine the oxygen analogue has not been discovered in natural compounds. Similarly, the chalcogen analogues of tryptophan and phenylalanine in which the benzene ring has been replaced by the largely isosteric thiophene, selenophene, and more recently, even tellurophene are fully synthetic mimics that are incorporated with more or less efficiency into proteins via the related tryptophanyl- and phenylalanyl-tRNA synthetases, respectively. In the serine/cysteine series, also selenocysteine is a proteinogenic amino acid that is inserted into proteins by a special translation mechanism, while the tellurocysteine is again most probably incorporated into proteins by the tolerance of the cysteinyl-tRNA synthetase. For research purposes, all of these natural and synthetic chalcogen amino acids have been extensively applied in peptide and protein research to exploit their different physicochemical properties for modulating structural and functional properties in synthetic peptides and rDNA expressed proteins as discussed in the following review

ETIICA study

Publisher Copyright: © European Stroke Organisation 2025.Introduction: Evidence regarding the benefit of endovascular therapy (EVT) in patients with acute ischemic stroke (AIS) due to isolated cervical internal carotid artery occlusion (c-ICA-O) is lacking. We assessed the outcomes and safety of EVT in patients with isolated c-ICA-O. Methods: Retrospective multicenter cohort study of patients with an AIS due to isolated c-ICA-O, within 24-h since last-seen-well. Comparisons were made between EVT and best medical therapy (BMT). The primary outcome was 3-months modified Rankin Scale (mRS) ordinal shift. Secondary outcomes included 3-month favorable outcome (mRS 0–2, or return to pre-stroke mRS), symptomatic intracranial hemorrhage (sICH) and any parenchymal hemorrhage. Outcomes were compared combining inverse probability of treatment weighting with regression models and propensity score matching (PSM) as sensitivity analysis. Results: We analyzed 998 patients (66.2% male, mean age 71.1 ± 13.2 years). 487 (48.8%) patients received EVT and 511 (51.2%) received BMT. Patients receiving EVT had a higher admission NIHSS [13 (7–18) vs 5 (2–13)] compared to BMT. There was no difference between EVT and BMT groups in 3-month mRS shift (adjusted common odds ratio [OR], 1.01 [95% CI 0.76–1.34]) and favorable outcome (adjusted OR [aOR] 1.16 [95% CI 0.84–1.60]). No patient (0%) in the BMT group had sICH versus 1.6% in the EVT group. Parenchymal hemorrhage was numerically higher in EVT patients (2.7% vs 0.6%; aOR 3.85 [95% CI 0.98–15.23]). PSM analysis revealed similar results. Discussion and conclusion: In patients with isolated c-ICA-O, EVT was associated with similar odds of disability and intracranial bleeding compared to BMT. Randomized-controlled clinical trials in patients with isolated c-ICA-O are warranted.publishersversioninpres