Protection of bacteria against toxicity of phenol by immobilization in calcium alginate

Summary The antibacterial activity of phenol was determined by measuring inhibition of exponentially growing free and immobilized cells of Escherichia coli, Pseudomonas putida and Staphylococcus aureus. Immobilization of microorganisms in calcium alginate beads reduced the growth inhibition caused by bacteriostatic concentrations of phenol. The increase in phenol tolerance occurred at different culture conditions and growth rates of the cells. The strength of the effect, however, was found to correlate with the formation of colonies in the gel matrix. Dissolution of gel beads led to a substantial loss of the protection against phenol of immobilized-grown cells.     

Self-segregation of myelin membrane lipids in model membranes

Rapid conduction of nerve impulses requires coating of axons by myelin sheaths, which are multilamellar, lipid-rich membranes produced by oligodendrocytes in the central nervous system. To act as an insulator, myelin has to form a stable and firm membrane structure. In this study, we have analyzed the biophysical properties of myelin membranes prepared from wild-type mice and from mouse mutants that are unable to form stable myelin. Using C-Laurdan and fluorescence correlation spectroscopy, we find that lipids are tightly organized and highly ordered in myelin isolated from wild-type mice, but not from shiverer and ceramide synthase 2 null mice. Furthermore, only myelin lipids from wild-type mice laterally segregate into physically distinct lipid phases in giant unilamellar vesicles in a process that requires very long chain glycosphingolipids. Taken together, our findings suggest that oligodendrocytes exploit the potential of lipids to self-segregate to generate a highly ordered membrane for electrical insulation of axons.     

Harn-steroidprofile hirsuter frauen

Urine steroid profiles of hirsute womenSteroid profiles of women suffering from idiopathic hirsutism show in more than 50% of the cases a 10–100 fold increase in the excretion of dehydroepiandrosterone (DHEA) compared with normal values.The excretion of DHEA was reduced much more than that of other 17-ketosteroids if the adrenals (NNR) were suppressed by dexamethasone (DXM). Within one week they reached values at the compound noise level of the gas chromatograms. If the ovaries were stimulated with human chorionic gonadotropin during continued suppression of the NNR with DXM no increase of DHEA could be detected.     

Studien an einheimischen Lumbriciden

Ohne ZusammenfassungAls Dissertation angenommen von der philosophischen Fakultät der Universität Köln.     

Subproteomic analysis of metal-interacting proteins in human B cells

Metal-protein interactions are vitally important in all living organisms. Metalloproteins, including structural proteins and metabolic enzymes, participate in energy transfer and redox reactions or act as metallochaperones in metal trafficking. Among metal-associated diseases, T cell mediated allergy to nickel (Ni) represents the most common form of human contact hypersensitivity. With the aim to elucidate disease-underlying mechanisms such as Ni-specific T cell activation, we initiated a proteomic approach to identify Ni-interacting proteins in human B cells. As antigen presenting cells, B cells are capable of presenting MHC-associated Ni-epitopes to T cells, a prerequisite for hapten-specific T cell activation. Using metal-affinity enrichment, 2-DE and MS, 22 Ni-interacting proteins were identified. In addition to known Ni-binding molecules such as tubulin, actin or cullin-2, we unexpectedly discovered that at least nine of these 22 proteins belong to stress-inducible heat shock proteins or chaperonins. Enrichment was particularly effective for the hetero-oligomeric TRiC/CCT complex, which is involved in MHC class I processing. Blue Native/SDS electrophoresis analysis revealed that Ni-NTA-beads specifically retained the complete protein machinery, including the associated chaperonin substrate tubulin. The apparent Ni-affinity of heat shock proteins suggests a new function of these molecules in human Ni allergy, by linking innate and adaptive immune responses.     

Iron Regulatory Proteins Control a Mucosal Block to Intestinal Iron Absorption

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Highlights? Disruption of intestinal IRP function constrains iron absorption in adult mice ? IRPs must limit mucosal ferritin for efficient iron absorption ? IRPs control ferroportin directly and DMT1 directly or through HIF2α ? IRPs define a set point for hepcidin-mediated regulation of iron absorption