Resistance and phylogeny guided discovery reveals structural novelty of tetracycline antibiotics.

Tetracyclines are a class of antibiotics that exhibited potent activity against a wide range of Gram-positive and Gram-negative bacteria, yet only five members were isolated from actinobacteria, with two of them approved as clinical drugs. In this work, we developed a genome mining strategy using a TetR/MarR-transporter, a pair of common resistance enzymes in tetracycline biosynthesis, as probes to find the potential tetracycline gene clusters in the actinobacteria genome database. Further refinement using the phylogenetic analysis of chain length factors resulted in the discovery of 25 distinct tetracycline gene clusters, which finally resulted in the isolation and characterization of a novel tetracycline, hainancycline (1).

Effects of mixture of lidocaine and ropivacaine at different concentrations on the central nervous system and cardiovascular toxicity in rats.

Background: Lidocaine and ropivacaine are often combined in clinical practice to obtain a rapid onset and a prolonged duration of action. However, the systemic toxicity of their mixture at different concentrations is unclear. This study aimed to compare the systemic toxicity of the mixture of ropivacaine and lidocaine at different concentrations when administered intravenously in rats.

{μ-6,6'-Dimeth-oxy-2,2'-[propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}trinitratocopper(II)erbium(III) acetone solvate.

In the title complex, [CuEr(C(19)H(20)N(2)O(4))(NO(3))(3)]·CH(3)COCH(3), the Cu(II) ion is coordinated in a square-planar environment by two O atoms and two N atoms of a Schiff base ligand. The Er(III) ion is bis-chelated by three nitrate ligands and coordinated by four O atoms of the Schiff base ligand in a slightly distorted bicapped square-anti-prismatic environment.