Norleucine, a natural occurrence in a novel ergot alkaloid γ-ergokryptinine

A novel natural peptide ergot alkaloid γ-ergokryptinine containing norleucine has been isolated from ergot sclerotia of the field-growing parasitic fungus Claviceps purpurea CCM 8059. Its structure was deduced from the NMR and mass spectral data. The final structural proof was provided by the crystal structure determination, which is the first X-ray structure of a natural Nle-containing secondary metabolite. The conformations of three ergopeptinines: γ-ergokryptinine, ergoladinine, and α-ergokryptinine were compared. © Springer-Verlag 2005

Application of the conservative averaging for the filtration problem with large velocity

In this paper we consider a filtration problem in a rectangle or a perturbed rectangle region with an essential nonlinearity and high values of velocity. The conservative averaging method with quadratic or rational approximation over the rectangle thickness gives us 1D problem instead of the original 2D problem. This ID solution can be used as an initial approximation for the original 2D problem. The conservative averaging method is considered and results of some numerical experiments are presented. Filtracijos uždavinio su dideliaias greičiais sprendimas konservatyviu vidurkinimo metodu Santrauka Straipsnyje sprendžiamas dvimatis filtracijos uždavinys. Sritis yra stačiakampe arba deformuota stačiakampe. Nagrinejamas atvejis, kai skysčio tekejimo greitis yra didelis ir būtina naudoti netiesini matematini modeli. Panaudojant vidurkinimo metoda y koordinates kryptimi sprendinys aproksimuojamas parabole, o lygtis yra vidurkinama. Gautoji vienmate difuzijos‐konvekcijos lygtis yra sprendžiama skaitiškai. Taip sudarytas sprendinys ne visada yra monotoniškas, todel nagrinejamas ir dar vienas artinys, kuris aprašomas racionalia trupmena. Pateikti skaičiavimo eksperimento rezultatai, gauti sprendžiant uždavini dviem atvejais, kai vyrauja konvekcijos procesas arba difuzijos procesas. Algoritmo ir iteracinio proceso konvergavimas nera ištirtas. First Published online: 14 Oct 201

Erratum: Resolution limitations for tailored picture-generating freeform surfaces ((2012) Optics Express 20:24 (26743))

Two typing errors in our manuscript are reported and corrected

Silybin reduces lipid peroxidation of rat hepatocyte membrane caused by cyclosporin A

An effect of cyclosporin A on lipid peroxidation in isolated rat hepatocytes was tested. A significant increase in lipid peroxidation marker (the concentration of lipofuscin-like pigments) was observed in samples incubated with cyclosporin A in comparison with the control. When hepatoprotective flavonoid silybin was added, the production of lipofuscin-like pigments decreased significantly. This result indicates a potential positive role of silybin in lowering of cyclosporin A side effects associated with the production of reactive oxygen species and plasma membrane damage

Metergoline II: structure solution from powder diffraction data with preferred orientation and from microcrystal

Metergoline is a dopamine agonist and serotonin antagonist used both in human and veterinary medicine. In addition to the previously known crystalline form, a new polymorph, which crystallizes from aqueous solution, was found. Since it was initially impossible to prepare a single crystal of quality suitable for single crystal X-ray diffraction measurements using a conventional laboratory source, the structure was solved from the powder diffraction data using synchrotron radiation. The structure determination also included solving the effects of preferred orientation. Characterization was simultaneously done by solid-state NMR spectroscopy. Finally, a small single crystal suitable for synchrotron diffraction was found after numerous tries. Crystal structure determination using this single crystal confirmed the powder-based solution. Comparison of information obtained by different experimental methods (powder diffraction, ssNMR, single crystal diffraction) was made