Surgical Management of Diffuse Sclerosing Variant of Papillary Thyroid Carcinoma. Experience in 25 Patients

Purpose: To delineate the clinicopathologic features and biologic behavior of the diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) and to report its outcome. Methods: The clinical records of 25 patients who had surgery for DSV-PTC from 2004 to 2017 were retrospectively analyzed. Comparisons were made to similar studies in the literature reporting ≥8 cases and a cohort of classical PTC. Results: There were 20 females and 5 males with an average age of 23 years (range 10–39 years). Bilateral disease occurred in 80% of cases. The mean size of the dominant mass was 4.2 ± 1.92 cm. In 92% of cases, therapeutic neck dissection was performed. Male sex significantly correlated with a higher yield of positive lymphadenopathy (p = 0.045). 62% of patients had recurrent disease. Recurrence significantly correlated with male sex, the number of metastatic lymph nodes (cutoff: 22 lymph nodes), and multifocality (p = 0.044, p ˂ 0.008, p ˂ 0.003, respectively). However, it did not correlate with the age at presentation. No disease-specific mortality occurred after an average follow-up of 77 months (range 12–168 months). The two comparisons made demonstrated a statistically significant greater tendency of the current series of DSV-PTC toward more aggressive clinicopathologic features and biologic behavior. No differences in overall survival were observed. Conclusion: The DSV-PTC should be considered a high-risk PTC that mandates an aggressive therapeutic strategy with the intent of optimizing disease-free survival

Metalation/De-metalation as a Post-Gelation Strategy to Tune the Mechanical Properties of Catenane-Crosslinked Gels

Mechanically interlocked molecules (MIMs) possess unique architectures and non-traditional degrees of freedom that arise from well-defined topologies that are achieved through precise mechanical bonding. Incorporation of MIMs into materials can thus provide an avenue to discover new and emergent macroscale properties. Here, the synthesis of a phenanthroline-based [2]catenane crosslinker and its incorporation into polyacrylate organogels is described. Specifically, Cu(I) metalation and de-metalation was used as a post-gelation strategy to tune the mechanical properties of a gel by controlling the conformational motions of integrated MIMs. The organogels were prepared via thermally initiated free radical polymerization, and Cu(I) metal was added in MeOH to pre-treated, swollen gels. De-metalation of the gels was achieved by adding cyanide salts and washing the gels. Changes in Young’s and shear moduli, as well as tensile strength, were quantified through oscillatory shear rheology and tensile testing. The reported approach provides a general method for post-gelation tuning of mechanical properties using metals and well-defined catenane topologies as part of a network architecture

Topologically Controlled Syntheses of Unimolecular Oligo[<i>n</i>]catenanes

Catenanes are a well-known class of mechanically interlocked molecules that possess chain-like architectures and have been investigated for decades as molecular machines and switches. However, the synthesis of higher-order catenanes with multiple, linearly interlocked molecular rings has been greatly impeded by the generation of unwanted oligomeric byproducts and figure-of-eight topologies that compete with productive ring closings. Here, we report two general strategies for the synthesis of oligo[n]catenanes that rely on a molecular “zip-tie” strategy, where the “zip-tie” is a central core macrocycle precursor bearing two phenanthroline (phen) ligands to make odd-numbered oligo[n]catenanes, or a preformed asymmetric iron(II) complex consisting of two macrocycle precursors bearing phen and terpyridine ligands to make even-numbered oligo[n]catenanes. In either case, preformed macrocycles or [2]catenanes are threaded onto the central “zip-tie” core using metal templation prior to ring-closing metathesis (RCM) reactions that generate several mechanical bonds in one pot. Using these synthetic strategies, a family of well-defined linear oligo[n]catenanes were synthesized, where n = 2, 3, 4, 5, or 6 interlocked molecular rings, and n = 6 represents the highest number of linearly interlocked rings reported to date for any isolated unimolecular oligo[n]catenane

Taking discourse seriously: discursive institutionalism and post-structuralist discourse theory

The article seeks to add to the growing contribution of discursive approaches to the study of political institutions by analysing the possibilities for cross-fertilisation between discursive institutionalism and post-structuralist discourse theory. Analysing Vivien Schmidt's version of discursive institutionalism, it argues that Schmidt's concept of discourse results in a model of explanation of institutional change that overlooks questions about the relations between power, politics and discourse. It further argues that while post-structural discourse theory has made important contributions to the understanding of the discursive nature of social practices, it has so far failed fully to take on board the institutional dimension of politics. It concludes that an integration of Schmidt's insights on discursive institutionalism with post-structuralist discourse theory allows a more rounded analysis of the political dimension of institutions and of the institutional dimension of politics, as well as a better understanding of institutional change. To illustrate our arguments we draw on our own research to analyse the relations between discourse and institutions in the 2002 presidential electoral campaign in Brazil and in Argentina's poverty reduction policies in the 1990s