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Stahnke H.,German Federal Institute for Risk Assessment | Kittlaus S.,Carl Zeiss GmbH | Kempe G.,Landesuntersuchungsanstalt fur das Gesundheits und Veterinarwesen Sachsen | Alder L.,German Federal Institute for Risk Assessment
Analytical Chemistry | Year: 2012

In this study, the relationship between matrix concentration and suppression of electrospray ionization (matrix effects) was investigated. Ion suppression of pesticides present in QuEChERS extracts was used as an example. Residue-free extracts of four different commodities, avocado, black tea, orange, and rocket (arugula), were fortified with 39 pesticides each. For many of the resulting 156 pesticide/matrix combinations, considerable matrix effects were observed if the coextracted matrix of 8 mg of equivalent sample (in the case of tea: 1.6 mg) was injected with the undiluted extracts. The reduction of these matrix effects was measured at 10 levels of dilution up to 1000-fold. The results obtained indicate a linear correlation between matrix effects and the logarithm of matrix concentration (or dilution factor) until the zero-effect level of further dilution was reached. Using the logarithmic equations, it could be shown that a dilution of extracts by a factor of 25-40 reduces ion suppression to less than 20% if the initial suppression is ≤80%. For stronger matrix effects or complete elimination of suppression, higher dilution factors were needed. The observed correlation was independent from the two instrument platforms used, but the degree of matrix effects differed slightly between the two mass spectrometers in this study. © 2011 American Chemical Society.


News Article | November 28, 2016
Site: www.eurekalert.org

Bekzod Khakimov, from the Department of Food Science at the University of Copenhagen, is the first recipient of the Nils Foss Talent Prize Bekzod Khakimov is one of the most promising young researchers that the Department of Food Science (FOOD) has educated in the last decade. He has published 13 scientific articles in the area of food science, plant science and metabolomics, mostly in highly ranked scientific journals and many more are in the pipeline. He is both proud and pleased to receive the award. "Receiving the first Nils Foss Talent Prize was fabulous and surprising news for me and it is the biggest achievement in my career. It makes me feel that our research goes beyond the Foodomics-lab at FOOD and is important both to science and to the food industry. I want to continue working towards establishing myself as an expert in this area and hope to create a research group in the future," says Bekzod Khakimov, who also cooperates with the Department of Plant and Environmental Sciences (PLEN) at the University of Copenhagen. In order to understand the complexity of food systems, food production and environment, we need reliable analytical systems and efficient data analysis. It is only a matter of time before the methods of Bekzod Khakimov will become standard and lead to considerably more robust and reliable data being produced from the analytical platforms in metabolomics/foodomics. "Foodomics emerged approximately a decade ago as a new field within the biochemical research area. It covers a broad spectrum analysis of foods, food raw materials and ingredients, and attempts to link food to human health and wellbeing. Foodomics also covers sustainable food production, detection of food fraud and food adulteration, as well as food authenticity," explains Bekzod Khakimov. He has already made two fundamental developments to improve the untargeted metabolomics approach using Gas Chromatography-Mass spectrometry (GC-MS). Currently, Bekzod Khakimov is building up a GC-MS database of food and plant metabolites, namely Copenhagen Open Metabolite DatabaSe (COMDAS) with the aim of making future metabolite assignments easier. Inspired by the rigorous standardization currently developed for NMR spectroscopy (Nuclear Magnetic Resonance) in metabolomics, Bekzod Khamimov is also working on establishing GC-MS with thoroughly optimized standard protocols (methods) to enhance data reproducibility and high-throughput analysis. Metabolomics is all about measuring metabolite levels in biological samples to understand their metabolism (synthesis and decomposition in cells) and reveals how internal and external factors (for example the impact of a particular diet) influences the metabolism. The result of a metabolomics study is thus a "fingerprint" of what has happened in the body/biological material. This fingerprint can be used to detect deviations from a given normal state using multivariate data analysis (chemometrics). Three major analytical platforms applied in modern metabolomics are Nuclear Magnetic Resonance (NMR), Liquid Chromatography-Mass Spectrometry (LC-MS), and GC-MS. The application of Bekzod Khakimov's methods has already led to a surprising biomarker that can differentiate people who are on a new Nordic diet from people who are on a traditional Danish diet based on their blood metabolome. He is also working with the German Federal Institute for Risk Assessment with the aim of using his method to detect wine adulteration and food fraud. Bekzod Khakimov has a background in chemistry and received his BSc from National University of Uzbekistan and MSc from Queen Mary University of London. He has received a PhD degree in Metabolomics from the University of Copenhagen (the Chemometrics and Analytical Technology section) in 2013. The Nils Foss Talent Prize of 100,000 DKK (14,000 US dollar) is awarded to a young and promising scientist annually and is the biggest of its kind. Through the Nils Foss Talent Prize, FOSS acknowledges the role of the food and agricultural community in the innovative application of technology for improved value and sustainability in the food supply chain. With the Prize, FOSS wants to further stimulate young and talented researchers in the agricultural and food sector. Read more about the Nils Foss prizes.


Przyrembel H.,Bolchener Strasse 10 | Przyrembel H.,German Federal Institute for Risk Assessment
Annals of Nutrition and Metabolism | Year: 2012

Complementary food is needed when breast milk (or infant formula) alone is no longer sufficient for both nutritional and developmental reasons. The timing of its introduction, therefore, is an individual decision, although 6 months of exclusive breastfeeding can be recommended for most healthy term infants. The new foods are intended to 'complement' ongoing breastfeeding with those dietary items whose intake has become marginal or insufficient. Both breastfeeding and complementary feeding can have direct or later consequences on health. The evaluation of consequences of both early and late introduction of complementary food can neither disregard the effect of breastfeeding compared to formula feeding nor the composition or quality of the complementary food. Possible short-term health effects concern growth velocity and infections, and possible long-term effects may relate to atopic diseases, type 1 and 2 diabetes, obesity and neuromuscular development. On the basis of the currently available evidence, it is impossible to exactly determine the age when risks related to the start of complementary feeding are lowest or highest for most of these effects, with the possible exception of infections and early growth velocity. The present knowledge on undesirable health effects, however, is mainly based on observational studies, and although some mechanisms have been proposed, further prospective studies have to clarify these unsolved issues. Even less evidence on the consequences of the timing of complementary food introduction is available for formula-fed infants. Copyright © 2012 S. Karger AG, Basel.


T cells play a pivotal role in sensitization and elicitation of type IV allergic reactions. While T helper cells sustain and maintain the differentiation of further effector cells, regulatory T cells are involved in control of cytokine release and proliferation, and T killer cells execute cellular lysis, thereby leading to certain levels of tissue damage. According to their central role, the widely applied and OECD-supported test method for the assessment of the sensitization potential of a chemical, i.e., the local lymph node assay (LLNA), relies on the detection of the immune-responsive proliferation of lymphocytes. However, most sensitization assays recently developed take advantage of the initiators of sensitization, dendritic cells (DCs) or DC-like cell lines. Here, we focus on inhibitory molecules expressed on the surface of DCs and their corresponding receptors on T cells. We summarize insight into the function of CTLA-4, the ligands of inducible co-stimulators (ICOSs), and on the inhibitory receptor programmed death (PD). The targeting of immune cell surface receptors by inhibitory molecules holds some promise with regard to the development of T cell-based sensitization assays. Firstly, a broader and more sensitive dynamic range of detection could be achieved by blocking inhibitors or by removing inhibiting regulatory T cells from the assays. Secondly, the actual expression levels of inhibitory molecules could be also a valuable indicator for the process of sensitization. Finally, inhibitory molecules in coculture test systems are supposed to have a major influence on DCs by reverse signaling, thereby affecting their differentiation and maturation status in a feedback loop. In conclusion, inhibitory ligands of DC surface receptors and/or their cognate receptors on T cells could serve as useful tools in cell-based assays, directly influencing toxicological endpoints such as sensitization.


Bol G.-F.,German Federal Institute for Risk Assessment
EMBO Reports | Year: 2016

The Ebola outbreak in West Africa is an instructive lesson on the difficulties of risk communication in times of crisis. The most effective strategy to improve communication during a crisis is to build public trust in officials and academics long before disaster strikes. © 2015 The Author.


Lassok B.,German Federal Institute for Risk Assessment | Tenhagen B.-A.,German Federal Institute for Risk Assessment
Journal of Food Protection | Year: 2013

Methicillin-resistant Staphylococcus aureus (MRSA) is a major global public health concern and could be a food safety issue. Recurrent reports have documented that pig herds are an important reservoir for MRSA, specifically the livestock-associated sequence type 398. The high prevalence of MRSA in pig primary production facilities and the frequent detection of MRSA of the same types in pork and pig meat products raise the question of underlying mechanisms behind the introduction and transmission of MRSA along the pork production chain. A comprehensive review of current literature on the worldwide presence of livestock-associated MRSA in various steps of the pork production chain revealed that the slaughter process plays a decisive role in MRSA transmission from farm to fork. Superficial heat treatments such as scalding and flaming during the slaughter process can significantly reduce the burden of MRSA on the carcasses. However, recontamination with MRSA might occur via surface treating machinery, as a result of fecal contamination at evisceration, or via increased human handling during meat processing. By optimizing processes for carcass decontamination and avoiding recontamination by effective cleaning and personal hygiene management, transmission of MRSA from pig to pork can be minimized. Copyright © International Association for Food Protection.


Bakhiya N.,German Federal Institute for Risk Assessment | Appel K.E.,German Federal Institute for Risk Assessment
Archives of Toxicology | Year: 2010

Furan is formed during commercial or domestic thermal treatment of food. The initial surveys of furan concentrations in heat-treated foods, published by European and US authorities, revealed the presence of relatively high furan levels in coffee, sauces, and soups. Importantly, furan is consistently found in commercial ready-to-eat baby foods. Furan induces hepatocellular tumors in rats and mice and bile duct tumors in rats with a high incidence. Epidemiological studies are not available. It is assumed that cis-2-butene- 1,4-dial, the reactive metabolite of furan, is the causative agent leading to toxicity and carcinogenicity. Based on this data, furan is classified as a possible human carcinogen. The initial exposure estimates revealed a relatively small margin (∼2,000) between human exposure and those furan doses, which induce liver tumors in experimental animals. As this may give rise for concern, in this review, the currently available toxicological and mechanistic data of furan are summarized and discussed with regard to its applicability in assessing the risk of furan in human diet. © 2010 Springer-Verlag.


Peiser M.,German Federal Institute for Risk Assessment
Clinical and Developmental Immunology | Year: 2013

Extending the classical concept considering an imbalance exclusively of T helper(h) 1 and Th2 cells on the bottom of many inflammatory diseases, Th17 cells were recently described. Today, there is sufficient experimental evidence to classify psoriasis and allergic contact dermatitis (ACD) amongst other inflammatory skin disorders as IL-17 associated diseases. In several human studies, T-cell-clones could be isolated from eczema biopsies, and high IL-17 levels were observed after challenge with allergen. In the last years, the phenotype of these IL-17 releasing T cells was in the focus of discussion. It has been suggested that Th17 could be identified by expression of retinoic acid receptor-related orphan receptor (ROR)C (humans) or RORγt (mice) and IL-17, accompanied by the absence of IFN-γ and IL-22. In cells from skin biopsies, contact allergens elevate IL-17A, IL-23, and RORC within the subset of Th cells. The indications for a participation of Th17 in the development of ACD are supported by data from IL-17 deficient mice with reduced contact hypersensitivity (CHS) reactions that could be restored after transplantation of wild type CD4+ T cells. In addition to Th17 cells, subpopulations of CD8+ T cells and regulatory T cells are further sources of IL-17 that play important roles in ACD as well. Finally, the results from Th17 cell research allow today identification of different skin diseases by a specific profile of signature cytokines from Th cells that can be used as a future diagnostic tool. © 2013 Matthias Peiser.


Dieckmann R.,German Federal Institute for Risk Assessment | Malorny B.,German Federal Institute for Risk Assessment
Applied and Environmental Microbiology | Year: 2011

Currently, 2,610 different Salmonella serovars have been described according to the White-Kauffmann-Le Minor scheme. They are routinely differentiated by serotyping, which is based on the antigenic variability at lipopolysaccharide moieties (O antigens), flagellar proteins (H1 and H2 antigens), and capsular polysaccharides (Vi antigens). The aim of this study was to evaluate the potential of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for rapid screening and identification of epidemiologically important Salmonella enterica subsp. enterica serovars based on specific sets of serovar-identifying biomarker ions. By analyzing 913 Salmonella enterica subsp. enterica strains representing 89 different serovars using MALDI-TOF mass spectrometry, several potentially serovar-identifying biomarker ions were selected. Based on a combination of genus-, species-, subspecies-, and serovar-identifying biomarker ions, a decision tree classification algorithm was derived for the rapid identification of the five most frequently isolated Salmonella enterica serovars, Enteritidis, Typhimurium/4,[5],12:i:-, Virchow, Infantis, and Hadar. Additionally, sets of potentially serovar-identifying biomarker ions were detected for other epidemiologically interesting serovars, such as Choleraesuis, Heidelberg, and Gallinarum. Furthermore, by using a bioinformatic approach, sequence variations corresponding to single or multiple amino acid exchanges in several biomarker proteins were tentatively assigned. The inclusivity and exclusivity of the specific sets of serovar-identifying biomarker ions for the top 5 serovars were almost 100%. This study shows that whole-cell MALDI-TOF mass spectrometry can be a rapid method for prescreening S. enterica subsp. enterica isolates to identify epidemiologically important serovars and to reduce sample numbers that have to be subsequently analyzed using conventional serotyping by slide agglutination techniques. © 2011, American Society for Microbiology.


Beutin L.,German Federal Institute for Risk Assessment | Martin A.,German Federal Institute for Risk Assessment
Journal of Food Protection | Year: 2012

An outbreak that comprised 3,842 cases of human infections with enteroaggregative hemorrhagic Escherichia coli (EAHEC) O104:H4 occurred in Germany in May 2011. The high proportion of adults affected in this outbreak and the unusually high number of patients that developed hemolytic uremic syndrome makes this outbreak the most dramatic since enterohemorrhagic E. coli (EHEC) strains were first identified as agents of human disease. The characteristics of the outbreak strain, the way it spread among humans, and the clinical signs resulting from EAHEC infections have changed the way Shiga toxin-producing E. coli strains are regarded as human pathogens in general. EAHEC O104:H4 is an emerging E. coli pathotype that is endemic in Central Africa and has spread to Europe and Asia. EAHEC strains have evolved from enteroaggregative E. coli by uptake of a Shiga toxin 2a (Stx2a)-encoding bacteriophage. Except for Stx2a, no other EHEC-specific virulence markers including the locus of enterocyte effacement are present in EAHEC strains. EAHEC O104:H4 colonizes humans through aggregative adherence fimbrial pili encoded by the enteroaggregative E. coli plasmid. The aggregative adherence fimbrial colonization mechanism substitutes for the locus of enterocyte effacement functions for bacterial adherence and delivery of Stx2a into the human intestine, resulting clinically in hemolytic uremic syndrome. Humans are the only known natural reservoir known for EAHEC. In contrast, Shiga toxin-producing E. coli and EHEC are associated with animals as natural hosts. Contaminated sprouted fenugreek seeds were suspected as the primary vehicle of transmission of the EAHEC O104:H4 outbreak strain in Germany. During the outbreak, secondary transmission (human to human and human to food) was important. Epidemiological investigations revealed fenugreek seeds as the source of entry of EAHEC O104:H4 into the food chain; however, microbiological analysis of seeds for this pathogen produced negative results. The survival of EAHEC in seeds and the frequency of human carriers of EAHEC should be investigated for a better understanding of EAHEC transmission routes. Copyright ©, International Association for Food Protection.

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