Über die Beeinflussung des Lichtbogens als spektrochemische Anregungsquelle mit Hilfe von Zusatzsubstanzen und homogenen Magnetfeldern

This report presents some basic investigations concerning the influence of additives and of a homogeneous magnetic field on the spectroscopic analysis of graphite and of titania-mixtures in a 10 Amp arc. The influence of a homogeneous magnetic field on the integral lineintensity of different trace-elements (Hg, Zn, Ga, TI) in graphite and on their axial and radial distribution in an arc-plasma is described in detail. Parameters were the strength of the magnetic field (0, 100, 200, 400 G) and the physical properties of the trace-elements, e. g. their mass and ionization potential. Besides, by non-destructive and continuous x-ray absorption measurements,the evaporation of some metal oxides from graphite anodes was determined and plotted against the strength of the magnetic field. As a particular result the influence of the added Ga$_{2}$O$_{3}$ on the lineintensity of trace elements in a graphite-matrix was found to depend on the concentration of Ga$_{2}$O$_{3}$ and the ionization potential of the elements investigated. In analysis of the titania-graphite mixtures it could be demonstrated that, contrary to PTFE as an additive, Ga$_{2}$O$_{3}$ has an arc stabilizing effect

Secretion of bioactive hepcidin-25 by liver cells correlates with its gene transcription and points towards synergism between iron and inflammation signaling pathways.

Contains fulltext : 71076.pdf (publisher's version ) (Closed access)Hepcidin is a small liver-derived peptide central in the regulation of systemic iron homeostasis. Although the gene regulation has been extensively studied at transcriptional level, the corresponding effects on the production of bioactive peptide are largely unknown. We therefore applied a proteomics-based approach by combining immunocapture with time-of-flight mass spectrometry to characterize hepcidin-25 produced by hepatocyte-derived cell lines. Similar to its transcriptional regulation, mature hepcidin-25 was strongly secreted upon stimulation with BMPs and IL-6. The immunocaptured peptide down-modulated iron-exporter ferroportin on the monocyte/macrophage surface. Further mass spectrometry-based analyses indicated that hepcidin-25 in its bioactive conformation was very stable in serum and urine and not converted into its smaller isoforms. Hepcidin-25 was processed in the Golgi apparatus from its precursor, while the unprocessed prohepcidin was secreted only when furin-like protease activity was intracellularly inhibited. Furthermore, the amounts of hepatocytic secretion of hepcidin-25 are highly correlated with the gene transcript levels. An unexpected observation was the synergistic effect of BMPs and IL-6 on hepcidin-25 secretion, which points towards cross-talk between iron and inflammatory stimuli. The study underscores hepcidin-25 quantification as a valuable tool to unravel regulatory pathways in iron metabolism

Increased exposure to bacterial antigen RpL7/L12 in early stage colorectal cancer patients.

Contains fulltext : 88060.pdf (publisher's version ) (Closed access)BACKGROUND: Cancer 2010. (c) 2010 American Cancer Society. : Intestinal bacteria have long been implicated in colorectal cancer pathology, and many reports point to a close linkage between Streptococcus bovis biotype I (recently renamed Streptococcus gallolyticus) infections and tumors of the human colon. This work aims to investigate the humoral immune response to this bacterium during different stages of colorectal cancer. METHODS: The presence of serum antibodies against S. bovis antigen RpL7/L12, previously assigned as a potential diagnostic antigen, was evaluated in Dutch (n = 209) and American (n = 112) populations using a newly developed enzyme-linked immunosorbent assay. RESULTS: The analyses consistently showed that an immune response against this bacterial antigen was increased in polyp patients and stage I/II colorectal cancer patients as compared with asymptomatic individuals. This was not paralleled by increased antibody production to endotoxin, an intrinsic cell wall component of the majority of intestinal bacteria, which implies that the humoral immune response against RpL7/L12 is not a general phenomenon induced by the loss of colonic barrier function. Notably, increased anti-RpL7/L12 levels were not or were only mildly detected in late stage colorectal cancer patients having lymph node or distant metastasis. CONCLUSIONS: Cancer 2010. (c) 2010 American Cancer Society. : These findings are indicative of an increased exposure to antigen RpL7/L12 during early stages of colon carcinogenesis and suggest that intestinal bacteria such as S. bovis constitute a risk factor for the progression of premalignant lesions into early stage carcinomas. Clearly, the current findings emphasize the necessity for further studies on the possible etiologic relationship between intestinal bacteria and human colorectal cancer