The Severity of Human Peri-Implantitis Lesions Correlates with the Level of Submucosal Microbial Dysbiosis

AIM To cross-sectionally analyse the submucosal microbiome of peri-implantitis (PI) lesions at different severity levels. MATERIALS AND METHODS Microbial signatures of 45 submucosal plaque samples from untreated PI lesions obtained from 30 non-smoking, systemically healthy subjects were assessed by 16s sequencing. Linear mixed models were used to identify taxa with differential abundance by probing depth, after correction for age, gender, and multiple samples per subject. Network analyses were performed to identify groups of taxa with mutual occurrence or exclusion. Subsequently, the effects of peri-implant probing depth on submucosal microbial dysbiosis were calculated using the microbial dysbiosis index. RESULTS In total, we identified 337 different taxa in the submucosal microbiome of PI. Total abundance of 12 taxa correlated significantly with increasing probing depth; a significant relationship with lower probing depth was found for 16 taxa. Network analysis identified two mutually exclusive complexes associated with shallow pockets and deeper pockets, respectively. Deeper peri-implant pockets were associated with significantly increased dysbiosis. CONCLUSION Increases in peri-implant pocket depth are associated with substantial changes in the submucosal microbiome and increasing levels of dysbiosis

Reactivity Consequences of Substituent-Dependent Preaggregation Motifs of n- and tert-Butyllithium towards 1,3,5-Triazacyclohexanes

Hülsmann M, Mix A, Neumann B, Stammler H-G, Mitzel NW. Reactivity Consequences of Substituent-Dependent Preaggregation Motifs of n- and tert-Butyllithium towards 1,3,5-Triazacyclohexanes. European Journal of Inorganic Chemistry. 2014;2014(1):46-50.The cyclic triaminal 1,3,5-tri-tert-butyl-1,3,5-triazacyclohexane (TtBuTAC) was treated with tBuLi, but instead of the expected deprotonation at a CH2 unit, the [(TtBuTAC)(tBuLi)] (2) adduct was formed. This is a monomeric tetracoordinate form of tBuLi; its molecular structure was determined by single-crystal X-ray diffraction (XRD) and it is likely to be monomeric in C6D6 solution according to H-1 NMR, C-13 NMR, and Li-7 NMR spectroscopy. TtBuTAC reacts with nBuLi to give a laddertype [(TtBuTAC)(nBuLi)(2)](2) aggregate of four nBuLi units terminated by two TtBuTAC ligands. This adduct was characterized by NMR spectroscopy and XRD. It slowly decays in solution, and minor quantities of a [TtBuTAC-Li(-nBu)](2)[Li-3(nBu)(2)N(tBu)(n-pent)] product were obtained and characterized by XRD. This compound contains amide units from the reaction of the formal monomer of TtBuTAC, Me3C-N=CH2, with nBuLi, which demonstrates the different types of reactivity of trisaminals such as TtBuTAC