Etablierung eines Frühwarnsystems zur Erkennung lebensmittelbedingter Risiken in Bayern – risikoorientierte Lebensmittelüberwachung weiter gefasst

Recent and past food scandals highlight the urgent need for food safety authorities to anticipate future risks in order to enable improved and proactive response mechanisms. With this goal in mind, the Bavarian Health and Food Safety Authority (LGL) has established an early warning system aimed at early identification of potential health risks and fraudulent practices in the food sector. The early warning approach allows intervention at different stages of risk development. On the one hand, the scanning of a broad area of the food production chain (horizon scanning) may enable prospective risk identification. To this end, relevant factors of influence (drivers) need to be identified, observed and analyzed. On the other hand, the retrospective analysis of case studies may unravel novel cause-effect associations that could be transferred to other products and production technologies, possibly leading to the identification of new drivers (root cause analysis). Additionally, various datasets emanating from food safety authorities, for example data from the European Rapid Alert System for Food and Feed (RASFF) and from Bavarian-wide laboratory analyses and food business inspections, will be closely observed and analyzed. The multidisciplinary character of the LGL has proven to be essential for the realization of the early warning approach, the analysis of inflowing data and implementation of consequences such as food business inspections and sampling for analysis. This article details the objectives and methodical approaches of the project. The acquisition of systematically compiled information as well as its analysis and assessment are comprehensively described. The early warning system presented here has already contributed significantly to the risk-oriented food inspection practiced to date, by integrating novel risk-relevant aspects.     

Immunological properties of human decidual macrophages--a possible role in intrauterine immunity

Our aim was to investigate the contribution of decidual macrophages, which constitute an important immune component of the decidua in late gestation, to intrauterine defence mechanisms. Using flow cytometry we examined the ability of decidual macrophages, isolated from term decidua, to bind and phagocytose fluorescence-labelled bacterial and yeast bioparticles. We also assessed their ability to generate superoxide radicals and tumour necrosis factor-alpha following lipopolysaccharide challenge. Decidual macrophages bound bacterial and yeast particles in a dose-dependent manner, which subsequently led to phagocytosis. These macrophages also produced superoxide radicals and the pro-inflammatory cytokine TNF-alpha when challenged with bacterial lipopolysaccharides. These results suggest a role for decidual macrophages in pathogen recognition and clearance during pregnancy, and, therefore, they are likely to protect the fetus against intrauterine infections which might otherwise lead to preterm labour.     

Ligation-dependent probe amplification for the simultaneous event-specific detection and relative quantification of DNA from two genetically modified organisms

The application of a ligation-dependent probe amplification (LPA) technique to the simultaneous event-specific detection and relative quantification of DNA from genetically modified organisms in foods is described. The system is based on the ligation of synthetic bipartite probes when hybridized to the corresponding target DNA sequence. The ligation products possess lengths characteristic for each target sequence. Universal primer binding sites (PBS) at the 5′ and 3′-ends enable their subsequent competitive amplification using one common pair of primers. The use of one fluorescein (FAM) labeled primer permits amplification products to be separated and detected via capillary electrophoresis. Respective probes were designed to allow the detection of reference genes in the genomes from maize and soya, as well as of event-specific junction regions in the transgenic maize line MON810 and in Roundup Ready soya. Specificity, sensitivity, and the potential of the technique for the relative quantification of recombinant DNA were assayed using mixtures of DNA extracted from certified reference maize and soybean flours. The novel strategy results in a modular system which can be complemented by further probes to broaden the range of target sequences.     

Thioarsenates in geothermal waters of Yellowstone National Park: determination, preservation, and geochemical importance

Mono-, di-, tri-, and tetrathioarsenate, as well as methylated arsenic oxy- and thioanions, were determined besides arsenite and arsenate in geothermal waters of Yellowstone National Park using anion-exchange chromatography inductively coupled plasma mass spectrometry. Retention time match with synthetic standards, measured S:As ratios, and molecular electrospray mass spectra support the identification. Acidification was unsuitable for arsenic species preservation in sulfidic waters, with HCI addition causing loss of total dissolved arsenic, presumably by precipitation of arsenic-sulfides. Flash-freezing is preferred for the preservation of arsenic species for several weeks. After thawing, samples must be analyzed immediately. Thioarsenates occurred over a pH range of 2.1 to 9.3 in the geothermal waters. They clearly predominated under alkaline conditions (up to 83% of total arsenic), but monothioarsenate also was detected in acidic waters (up to 34%). Kinetic studies along a drainage channel showed the importance of thioarsenates for the fate of arsenic discharged from the sulfidic hot spring. The observed arsenic speciation changes suggest three separate reactions: the transformation of trithioarsenate to arsenite (major initial reaction), the stepwise ligand exchange from tri- via di- and monothioarsenate to arsenate (minor reaction), and the oxidation of arsenite to arsenate, which only becomes quantitatively important after thioarsenates have disappeared.     

Volatile metals and metalloids in hydrothermal gases

Volatile metals and metalloids were sampled from hot springs, fumaroles, and a hydrothermally influenced wetland in Yellowstone National Park. The sampling was based on diffusion through gas sampling chambers. Collected gases were stabilized by dissolution and oxidation in 1:100 diluted NaOCl. Special procedures were developed to analyze the oxidized samples by GF-AAS and HG-AAS. For ICP-MS, samples had to be blank-corrected for polyatomic isotope interferences, especially by 23Na35Cl+ and 23Na37Cl+ on 58Ni and 60Ni and by 40Ar23Na+ on 63Cu. From the concentrations trapped in solution, net diffusion rates were calculated by Fick's first law. The highest concentrations reached a maximum of 8 g/m3 for volatile silicon. Volatile nickel, tungsten, zinc, copper, and molybdenum, previously only known from anthropogenic sources, occurred naturally in the hydrothermal gases in ranges of tens to hundreds of microg/m3. Replicate measurements indicated significant temporal variations in concentrations, probably the result of complex changes in the hydrothermal regime as well as varying microbial activity. Global correlations between gaseous and superficial aqueous phases were missing.