Validation and comparison of a sandwich ELISA,two competitive ELISAs and a real-time PCR method for the detection of lupine in food

Methods applied in food allergen analysis should be specific, sensitive and applicable to both raw and highly processed foods. The performance of the most commonly used methods, ELISA and real-time PCR, may, however, be influenced by food processing steps, e.g., heat treatment. The present study compares the applicability of four in-house developed methods, one sandwich ELISA, two competitive ELISAs and a real-time PCR method, for the detection of lupine in four different food matrices, comprising bread, biscuits, rice patties and noodles. In order to investigate the influence of food processing on the detectability, not only the heat treated model foods but also the corresponding doughs were analysed. The sandwich ELISA proved to be the most sensitive method. The LOD was found to be 10 ppm lupine, independent from the food matrix and independent if the dough or the heat treated food was analysed. In addition, the methods were applied to the analysis of commercial foodstuffs differing in their labelling.     

Production of the Carboxylate Reductase from Nocardia otitidiscaviarum in a Soluble,Active Form for in vitro Applications

Accessing aldehydes from carboxylate moieties is often a challenging task. In this regard, carboxylate reductases (CARs) are promising catalysts provided by nature that are able to accomplish this task in just one step, avoiding over-reduction to the alcohol product. However, the heterologous expression of CARs can be quite difficult due to the excessive formation of insoluble protein, thus hindering further characterization and application of the enzyme. Here, the heterologous production of the carboxylate reductase from Nocardia otitidiscaviarum (NoCAR) was optimized by a combination of i) optimized cultivation conditions, ii) post-translational modification with a phosphopantetheinyl transferase and iii) selection of an appropriate expression strain. Especially, the selection of Escherichia coli tuner cells as host had a strong effect on the final 110-fold increase in the specific activity of NoCAR. This highly active NoCAR was used to reduce sodium benzoate to benzaldehyde, and it was successfully assembled with an in vitro regeneration of ATP and NADPH, being capable of reducing about 30 mM sodium benzoate with high selectivity in only 2 h of reaction.     

FLASH CALCULATIONS FOR A CRUDE OIL BY CONTINUOUS THERMODYNAMICS

Continuous thermodynamics is a suitable concept for performing phase equilibrium calculations of complex multi-component mixtures. In contrast to the traditional pseudo-component method, the continuous distribution density function obtained by the characterization experiment is used directly for the thermodynamic calculations.

This paper describes the application of continuous thermodynamics to flash calculations for a crude oil. In the simple version the coexisting phases are assumed to behave ideally. In the refined version the real behavior is accounted for describing non-aromatics and aromatics as two different continuous ensembles.

It proves possible to separate in the calculations the problem of the compositions in the coexisting vapor and liquid phases from the problem of the equilibrium temperatures. For the compositions exact explicit equations are provided.

To obtain the equilibrium temperatures the numerical solution of only one equation (in the simple version) or of a system of only three equations (in the refined version) is required. The refined as well as the simple version lead to good coincidence with experimental data     

Sense-making strategies in explorative intelligence analysis of network evolutions

Visualising how social networks evolve is important in intelligence analysis in order to detect and monitor issues, such as emerging crime patterns or rapidly growing groups of offenders. It remains an open research question how this type of information should be presented for visual exploration. To get a sense of how users work with different types of visualisations, we evaluate a matrix and a node-link diagram in a controlled thinking aloud study. We describe the sense-making strategies that users adopted during explorative and realistic tasks. Thereby, we focus on the user behaviour in switching between the two visualisations and propose a set of nine strategies. Based on a qualitative and quantitative content analysis we show which visualisation supports which strategy better. We find that the two visualisations clearly support intelligence tasks and that for some tasks the combined use is more advantageous than the use of an individual visualisation.     

Dealing with orthographic variation in a tagger-lemmatizer for fourteenth century Dutch charters

In this paper we describe a tagger-lemmatizer for fourteenth century Dutch charters (as found in the corpus van Reenen/Mulder), with a special focus on the treatment of the extensive orthographic variation in this material. We show that despite the difficulties caused by the variation, we are still able to reach about 95 % accuracy in a tenfold cross-validation experiment for both tagging and lemmatization. We can deal effectively with the variation in tokenization (as applied by the authors) by pre-normalization (retokenization). For variation in spelling, however, we choose to expand our lexicon with predicted spelling variants. For those forms which can also not be found in this expanded lexicon, we first derive the word class and subsequently search for the most similar lexicon word. Interestingly, our techniques for recognizing spelling variants turn out to be vital for lemmatization accuracy, but much less important for tagging accuracy.     

The degree of visual cover and location of birth fluids affect dairy cows' choice of calving site

Under natural conditions, cows seek isolation and visual cover when calving becomes imminent, but the degree of visual cover necessary to provide an attractive calving site is not known. When calving indoors, preparturient cows are attracted to other cows' birth fluids, and this may influence their isolation seeking. Therefore, we aimed to investigate the effect of degree of visual cover of secluded areas and the location of birth fluids on dairy cows' calving site selection. One hundred twenty-four Danish Holstein cows were moved in groups of 8 to 12 to a group pen with access to 6 areas secluded by a barrier of either 3 m (wide barrier) or 1.5 m (narrow barrier). Sixty cows calved within 14 d of having been moved to the group pen and were included in the study. From 3 h before partition and until the cow and calf were removed from the pen within 3 h after parturition, the location and posture of cows were recorded, along with the location of where their birth fluids were discharged. In addition, location and posture of calves were recorded during and up to 3 h after calving. All data were collected from continuous video recordings. Continuous data for location and behavior were analyzed by mixed models, binary data were analyzed by chi-squared analysis, and location of calving relative to where the cow's own or alien birth fluids were discharged was analyzed using logistic regression models. Ten percent of the cows calved in a secluded area, with no effect of barrier width. However, before calving, cows with access to secluded areas with a wide barrier spent more time in a secluded area (22 vs. 7 min/3 h), and more cows were observed lying there (58 vs. 28%) than cows with access to secluded areas with a narrow barrier. Secluded areas with a wide barrier were used by more cows and calves during the first hour after calving (36 vs. 10%). Among the cows that entered a secluded area after calving, the latency to enter correlated with their calf's latency to enter, suggesting that the 2 sought seclusion together. Seventy-nine percent of the cows calved in proximity (within a 1.25-m radius) to their own or an alien cow's birth fluids. There was no effect of barrier width on the probability of calving in proximity to their own or alien birth fluids. However, the probability of calving in proximity to their own or alien birth fluids was higher than the probability of not doing so. The greater use of secluded areas with a 3-m-wide barrier before and after parturition suggests that these are preferred over areas with a 1.5-m-wide barrier. Only a few cows calved in a secluded area, and more research is needed to explore the environmental and social factors affecting parturient cows' use of designated calving areas. The majority of cows calved close to where their own or alien birth fluids were discharged, suggesting that cows are attracted to these before calving. This may have affected the use of secluded areas as calving sites.     

Development and validation of a sandwich ELISA for the determination of potentially allergenic lupine in food

The paper presents a sandwich enzyme linked immunosorbent assay (ELISA) for the detection of traces of lupine proteins in foods. Anti-lupine antibodies were produced by immunising a rabbit and a hen with a protein extract from white lupine flour. IgY were used as coating and IgG as secondary antibodies. The ELISA detects proteins from white (Lupinus albus) and blue (Lupinus angustifolius) lupine and, with a lower sensitivity, proteins from yellow (Lupinus luteus) lupine. The ELISA does not show any cross-reactivity with 34 plant species potentially used in lupine containing foodstuffs. Accuracy, repeatability, limit of detection (LOD) and limit of quantification (LOQ) were determined by analysing model biscuits and noodles containing from 0 to 10,000 ppm lupine flour. Lupine flour could be detected in the unprocessed doughs as well as in the processed products down to a spiking level of 1 ppm.     

Genetic research on complex behaviors: an examination of attempts to identify genes for smoking.

A conference on the conduct of genomic research on complex behaviors was convened at the University of Michigan to demystify genetic research by describing the tools and methodologies for identifying genes and to assess the feasibility of conducting genomic research on smoking, a complex behavior with major public health import. These proceedings are excerpts based on the presentations at the conference.     

Sensory, chemical and sensometric studies of hydrolyzed vegetable protein produced by various processes

 Nine protein hydrolysates were made from untoasted defatted soygrits by acid hydrolysis, enzymatic hydrolysis for 4 h (EVP4) or 10 h (EVP10) followed by addition of monosodiumglutamate (MSG) or heating with xylose (EVP4xyl, EVP10xyl), xylose and cysteine (EVP10xylcys) or undissolved matters (EVP10un). The hydrolysates were evaluated for taste-donor and taste-enhancer effects. The taste-donor effect was mostly due to the volatile compounds while the taste-enhancing effect was more influenced by the amino acids. The acid hydrolysis product was different from the enzymatic hydrolysis products, even those that underwent MSG addition and heating. Heating of the hydrolysates resulted in bitter and malty tastes, which seemed to be due to pyrazines. Heating with undissolved matters resulted in the least bitter hydrolysate. MSG addition had the most influence on the taste-donor effect of the hydrolysates. Hydrolysis for 4 h seemed to be sufficient for taste-enhancing and for reaction by heating, but not enough to provide a specific taste-donor effect. Received: 10 December 1998     

Magnetfluide als Dichtmaterial in Drehdurchführungen sorgen für höchste Reinheit im Vakuum

Rotary feedthroughs are used whereever rotary motions have to be transmitted into a vacuum chamber. These rotary feedthroughs have to constructed with a sealing technique which hermetically isolates the vacuum side from the ambient space in order to avoid any contamination inside the vacuum chamber. Magnetic fluids as the sealing technology is the adequate solution. We describe the principle of Magnetic Fluids and several applications of Magnetic Fluids used as the sealing technology in rotary feedthroughs.