Evaluation of a new model system for studying the formation of heterocyclic amines.

Heterocyclic amines (HAs) are an important class of food mutagens and carcinogens, which can be found in cooked meat and fish. Increasing heating temperatures and times usually increase mutagenic activity in meat and meat extracts during cooking. We developed a model system, which allows to examine the effects of precursor composition and heating conditions (time and temperature) on the formation of HAs in meat. Homogenized and freeze dried meat samples (beef, pork chops, chicken breast and turkey breast) are heated with diethylene glycol in closed vials under stirring in a thermostated heating block. After an appropriate sample preparation (extraction and clean-up) ten different HAs were measured by HPLC analyses with gradient elution and mass selective detection. The time courses of HA-formation in the different kinds of meat at varying heating temperatures were determined up to heating times of 30 min. 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was the most abundant HA in these experiments and reached the highest concentrations in the beef meat samples, as did the other HAs (MeIQ, AalphaC) at 220 degrees C in the heating block under stirred conditions. Additionally the influence of the antioxidant TBHQ (t-butylhydroquinone) on the formation of HAs in the model system was tested. However TBHQ effected only slight reductions of HA formation in all kinds of meat.

Analysis of heterocyclic amines in food products: interlaboratory studies.

A feasibility study and two interlaboratory exercises on the determination of selected heterocyclic amines (HAs) in beef extract, organised in the framework of a European project, are presented. The aim of these exercises was to improve the quality of the laboratories and to evaluate the performance of a standardised analytical method and also the methods currently used by each of the participants for the analysis of these compounds. Three lyophilised portions of a commercial beef material previously spiked with HAs at different concentration levels ranging from 10 to 75 ng g(-1) were used as laboratory reference materials (lot A, B and C). Firstly, a feasibility study was carried out using a test standard solution and the beef extract (lot A), which contained only five HAs. Then, two interlaboratory exercises were carried out using the laboratory reference materials lot B and lot C, containing 10 selected HAs at two different concentration levels, 75 and 10 ng/g, respectively. The results obtained by all participant laboratories using the proposed method showed satisfactory agreement and the CV(%) between-laboratories obtained were from 8.3 to 24.1% for lot B and from 8.7 to 44.5% for lot C. The standardised method evaluated in these collaborative studies is therefore proposed for the analysis of HAs in food material. Moreover, LC-MS is recommended as the most suitable technique for the analysis of a large number of HAs in food samples.

How do indirect measures of evaluation work? Evaluating the inference of prejudice in the Implicit Association Test.

There has been significant interest in indirect measures of attitudes like the Implicit Association Test (IAT), presumably because of the possibility of uncovering implicit prejudices. The authors derived a set of qualitative predictions for people's performance in the IAT on the basis of random walk models. These were supported in 3 experiments comparing clearly positive or negative categories to nonwords. They also provided evidence that participants shift their response criterion when doing the IAT. Because of these criterion shifts, a response pattern in the IAT can have multiple causes. Thus, it is not possible to infer a single cause (such as prejudice) from IAT results. A surprising additional result was that nonwords were treated as though they were evaluated more negatively than obviously negative items like insects, suggesting that low familiarity items may generate the pattern of data previously interpreted as evidence for implicit prejudice.

Reactive oxygen intermediate-release of fibre-exposed monocytes increases inflammatory cytokine-mRNA level, protein tyrosine kinase and NF-kappaB activity in co-cultured bronchial epithelial cells (BEAS-2B).

Some pulmonary diseases like bronchitis or asthma bronchiale are mediated by inflammatory mechanisms in bronchial epithelial cells. Alveolar macrophages are located directly in the surrounding of these cells, so that we suppose an interaction between epithelial cells and macrophages regarding to the release of inflammatory mediators. For measuring the contribution of macrophages to the release of inflammatory mediators by bronchial epithelial cells, we established an in vitro model of co-cultured blood monocytes (BM) and BEAS-2B cells in a transwell system (Costar). BM were exposed to Chrysotile B and soot particle FR 101 in a concentration of 100 microg/10(6) cells. After up to 90 min exposure time ELISA, EMSA (electromobility shift assay) and RT-PCR were used to measure protein tyrosine kinase activity, protein activity of NF-kappaB and cytokine (IL-1beta, IL-6, TNF-alpha) specific mRNA levels in BEAS-2B cells. We observed an increase in protein tyrosine kinase activity (up to 1.8 +/- 0.5-fold) and NF-kappaB protein activity in BEAS-2B cells after particle or fibre exposure of co-cultured BM. Consecutive IL-1beta-, IL-6- and TNF-alpha-mRNA were elevated (up to 1.9 +/- 0.58-fold). Protein tyrosine kinase activity, NF-kappaB activity, and the synthesis of cytokine-specific mRNA were inhibited by antioxidants. These data suggest a ROI-dependent NF-kappaB mediated transcription of inflammatory cytokines in bronchial epithelial cells.