NACE–ESI-MS/MS method for separation and characterization of phosphorylation and acylation isomers of lipid A

Lipid A represents a heterogeneous group of bacterial outer membrane phosphoglycolipids, which play a major role in the pathogenesis of Gram-negative sepsis. The number and position of phosphoryl and acyl groups in lipid A molecules are key structural determinants in their bioactivities. In this study, a NACE–ESI-MS/MS method was developed for the simultaneous analysis of lipid A isomers possessing a different degree of phosphorylation and acylation. Various C4’- and C1-monophosphorylated lipid A isobars, as well as acylation isomers, were baseline separated within 43 min in a separation medium of methanol/dichloromethane/triethylamine/acetic acid 60:40:1.08:0.36 (v/v/v/v). Both normal and reverse CE polarities could be applied for proper detection of the analytes owing to the combination of a suction effect caused by the nebulizer gas at the outlet end of the capillary and external pressure applied on the inlet vial. The separated lipid A species could be identified unequivocally by their characteristic fragmentation patterns through CID performed in both negative- and positive-ionization modes. The uniqueness of the NACE–ESI-MS/MS method lies in its simplicity and reliability for proving the phosphorylation isomerism (C1 or C4’) and acylation pattern of native lipid A species or those designed for therapeutic applications.     

Differential thermal analysis of the antibacterial effect of PLA-based materials planned for 3D printing

Journal of Thermal Analysis and Calorimetry - Additive manufacturing technologies give many new application possibilities in our everyday life. Biomedical applications benefit a lot from 3D...     

Squalyl Crown Ether Self‐Assembled Conjugates: An Example of Highly Selective Artificial K+ Channels

The natural KcsA K⁺ channel, one of the best‐characterized biological pore structures, conducts K⁺ cations at high rates while excluding Na⁺ cations. The KcsA K⁺ channel is of primordial inspiration for the design of artificial channels. Important progress in improving conduction activity and K⁺/Na⁺ selectivity has been achieved with artificial ion‐channel systems. However, simple artificial systems exhibiting K⁺/Na⁺ selectivity and mimicking the biofunctions of the KcsA K⁺ channel are unknown. Herein, an artificial ion channel formed by H‐bonded stacks of squalyl crown ethers, in which K⁺ conduction is highly preferred to Na⁺ conduction, is reported. The K⁺‐channel behavior is interpreted as arising from discreet stacks of dimers resulting in the formation of oligomeric channels, in which transport of cations occurs through macrocycles mixed with dimeric carriers undergoing dynamic exchange within the bilayer membrane. The present highly K⁺‐selective macrocyclic channel can be regarded as a biomimetic alternative to the KcsA channel.     

Role of direct bioautographic method for detection of antistaphylococcal activity of essential oils

The aim of the present study was the chemical characterization of some traditionally used and therapeutically relevant essential oils (thyme, eucalyptus, cinnamon bark, clove, and tea tree) and the optimized microbiological investigation of the effect of these oils on clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA). The chemical composition of the oils was analyzed by TLC, and controlled by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The antibacterial effect was investigated using a TLC-bioautographic method. Antibacterial activity of thyme, clove and cinnamon oils, as well as their main components (thymol, carvacrol, eugenol, and cinnamic aldehyde) was observed against all the bacterial strains used in this study. The essential oils of eucalyptus and tea tree showed weak activity in the bioautographic system. On the whole, the antibacterial activity of the essential oils could be related to their most abundant components, but the effect of the minor components should also be taken into consideration. Direct bioautography is more cost-effective and better in comparison with traditional microbiological laboratory methods (e.g. disc-diffusion, agar-plate technique).     

Rigid impacts of three-dimensional rocking structures

Studies of rocking motion aim to explain the remarkable earthquake resistance of rocking structures. State-of-the-art assessment methods are mostly based on planar models, despite ongoing efforts to understand the significance of three-dimensionality. Impacts are essential components of rocking motion. We present experimental measurements of free-rocking blocks on a rigid surface, focusing on extreme sensitivity of impacts to geometric imperfections, unpredictability, and the emergence of three-dimensional motion via spontaneous symmetry breaking. These results inspire the development of new impact models of three-dimensional facet and edge impacts of polyhedral objects. Our model is a natural generalization of existing planar models based on the seminal work of George W. Housner. Model parameters are estimated empirically for rectangular blocks. Finally, new perspectives in earthquake assessment of rocking structures are discussed.

     

5-Aminosalicyls?ure als Fluoreseenzindikator

Ohne Zusammenfassung     

Monitoring of enzyme catalysed reactions by Fourier transform Raman spectrometry

Esterification of mandelic acid catalysed by Candida antarctica lipase B was studied by Fourier transform (FT) Raman spectrometry in non-aqueous medium. It was found that there is a strict correlation between the intensity of the Raman scattering and the activity of the enzyme. FT-Raman spectrometry seems to be a fast and reliable method for selecting the appropriate enzyme and for determining the optimal enzyme water content. In addition, valuable information can be obtained from the spectra regarding the mechanism of enzyme–substrate bonding.     

Photographic observation of aluminum micropellet ablation in theMT-1M tokamak plasma

Laser beam accelerated aluminum micropellets were injected into the MT-1M tokamak plasma, and the distribution of characteristic line radiation of aluminum atoms and ions of different charge state was detected. The investigations are focused on the visualization of the pellet cloud, on the bending of the pellet path, and on the striation occurring in the radiation of different charge state along the pellet path in the plasma     

The Stability of a Sum Form Functional Equation Arising in Information Theory

The stability of a sum form equation due to M. Behara and P. Nath will be discussed. The main tools are stability results for Cauchy type functional equations on restricted domains.     

Advances in crystal analyzers for inelastic X-ray scattering

The realization of spherical crystal analyzers for inelastic X-ray scattering experiments (IXS) is an ongoing project at the ESRF since 1992. We developed reliable techniques to routinely produce silicon spherical analyzers with very high (ΔE=1÷10 meV) and high energy resolution (ΔE=0.2÷1.5 eV), and with very good focal properties and efficiency. In this article we report the state of the art of the analyzer construction and the main improvements made during the last years.