Growth of the A549 cell line in a perfusion system suitable for use in a magnetic resonance study has been characterized and shown to be stable physiologically and hence appropriate for serial observations. Several methods of monitoring cell growth were compared to assess the behavior of the cells in this system. Comparison between NMR metabolite data and cell growth via cell counting showed that 31P NMR signals accurately reported cell doubling time. In contrast to most NMR cell culture systems, viable cells can be recovered from the perfusion system after the NMR measurements for further biochemical studies. These data further suggest that this system will be useful for studying the physiology and biochemistry of exponentially growing cells for at least two days in NMR tube culture., E. G. Shankland, J. C. Livesey, R. W. Wiseman, K. A. Krohn., and Obsahuje bibliografii
In the frame of advanced studies of coal structure the temperature conditions of coal origin were investigated through thermal stability of aluminum complexes in coal substance. These compounds were discovered by solid-state nuclear magnetic resonance measurements of 27Al as a part of coal substance closely bonded to organic mass of coal. In obtained spectra, Al-hexaphenoxide and Al-tetrahydroxy-diphenoxide complexes were identified. These complexes were further prepared and their thermal stability tested by thermal analysis method. It was found that a) they can originate under room temperature and atmospheric pressure and b) they are thermally stable only up to approximately 85 or 95 °C. As both Al-hexaphenoxide and Al-tetrahydroxy-diphenoxide complexes are the integrated constituents of coal substance it can be deduced that, in the beginning, coal was formed under very mild thermal conditions. As investigated materials, coals and clays from the Czech basins and gagatite from Poland were measured., Pavel Straka and Jana Náhunková., and Obsahuje bibliografii
The solid-state NMR measurements play an indispensable role in studies of interactions between biological membranes and peptaibols, which are amphipathic oligopeptides with a high abundance of α-aminobutyric acid (Aib). The solid-state NMR investigations are important in establishing the molecular models of the pore forming and antimicrobial properties of peptaibols, but rely on certain simplifications. Some of the underlying assumptions concern the parameters describing the 15N NMR chemical shielding tensor (CST) of the amide nitrogens in Aib and in conventional amino acids. Here the density functional theory (DFT) based calculations were applied to the known crystal structure of one of peptaibols, Ampullosporin A, in order to explicitly describe the variation of the 15N NMR parameters within its backbone. Based on the DFT computational data it was possible to verify the validity of the assumptions previously made about the differences between Aib and other amino acids in the isotropic part of the CST. Also the trends in the magnitudes and orientations of the anisotropic components of the CST, as revealed by the DFT calculations of the full periodic structure of Ampullosporin A, were thoroughly analyzed, and may be employed in future studies of peptaibols., J. Czernek, J. Brus., and Obsahuje bibliografii