The genetic background of antibiotic resistance among clinical uropathogenic Escherichia coli strains

Molecular Biology Reports - The spreading mechanisms of antibiotic resistance are related to many bacterial and environment factors. The overuse of antibiotics is leading to an unceasing emergence...     

Structural studies of the O-specific polysaccharide of Hafnia alvei strain PCM 1207 lipopolysaccharide.

The structure of the O-specific side-chain of the Hafnia alvei strain PCM 1207 lipopolysaccharide (LPS) has been investigated. Methylation analysis, partial acid hydrolysis, matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) MS, fast atom bombardment (FAB)-MS/MS and 1H- and 13C-NMR spectroscopy were the principal methods used. Glycerol phosphate was identified as a constituent in the polysaccharide and the following structure of a pentasaccharide repeating unit was established: The polysaccharide is partially (approximately 10%) substituted with O-acetyl groups. The lipopolysaccharide was also subjected to high resolution magic angle spinning (HR-MAS) NMR analysis, which showed both the signals of the O-specific polysaccharide as well as several signals from unsubstituted core oligosaccharides. This confirmed the presence of the described structure in the native LPS.     

ZAP-70 and CD38 expression are independent prognostic factors in patients with B-cell chronic lymphocytic leukaemia and combined analysis improves their predictive value

Recently identified biological risk factors in B-cell chronic lymphocytic leukemia (B-CLL) include ZAP-70 and CD38 expression. The present study was conducted to clarify whether a combined analysis could improve predictive impact of these two parameters. We examined the expression of ZAP-70 and CD38 by flow cytometry method in 217 newly diagnosed, consecutive, unselected and well characterized B-CLL patients in relation to laboratory parameters and clinical outcome. We confirmed that both ZAP-70 as well as CD38 were independent of prognostic factors. There was a significant correlation between the percentage of leukemic cells positive for ZAP-70 and the percentage of CD38+CD19+ cells (R=0.629; p=0.000001). Combined analysis of ZAP-70 and CD38 showed concordant results in 158/217 patients (72.8%), while in 59 patients the results were discordant (27.2%). A mean treatment free survival (TFS) was the longest in ZAP-70-CD38-patients (45.6 months, comparing to 13.6 months in ZAP-70+CD38+ group). Also a mean overall survival was the longest in ZAP-70-CD38- patients (224.7 months compared to 77.9 months in ZAP-70+CD38+ patients).     

Pyrazole amino acids: hydrogen bonding directed conformations of 3‐amino‐1H‐pyrazole‐5‐carboxylic acid residue

A series of model compounds containing 3‐amino‐1H‐pyrazole‐5‐carboxylic acid residue with N‐terminal amide/urethane and C‐terminal amide/hydrazide/ester groups were investigated by using NMR, Fourier transform infrared, and single‐crystal X‐ray diffraction methods, additionally supported by theoretical calculations. The studies demonstrate that the most preferred is the extended conformation with torsion angles ? and ψ close to ±180°. The studied 1H‐pyrazole with N‐terminal amide/urethane and C‐terminal amide/hydrazide groups solely adopts this energetically favored conformation confirming rigidity of that structural motif. However, when the C‐terminal ester group is present, the second conformation with torsion angles ? and ψ close to ±180° and 0°, respectively, is accessible. The conformational equilibrium is observed in NMR and Fourier transform infrared studies in solution in polar environment as well as in the crystal structures of other related compounds. The observed conformational preferences are clearly related to the presence of intramolecular interactions formed within the studied residue. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

Referate

Ohne Zusammenfassung