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Vitamin E and carotenoids are fat-soluble microconstituents that may exert beneficial effects in humans, including protection against cancer, cardiovascular diseases, and age-related eye diseases. Their bioavailability is influenced by various factors including food matrix, formulation, and food processing. Since human studies are labor-intensive, time-consuming, and expensive, the in vitro model used in this study is increasingly being used to estimate bioaccessibility of these microconstituents. However, the ability of this model to predict bioavailability in a healthy human population has not yet been verified. The first aim of this study was to validate this model by comparing model-derived bioaccessibility data with (i) human-derived bioaccessibility data and (ii) published mean bioavailability data reported in studies involving healthy humans. The second aim was to use it to measure alpha- and gamma-tocopherol, beta-carotene, lycopene, and lutein bioaccessibility from their main dietary sources. Bioaccessibility as assessed with the in vitro model was well correlated with human-derived bioaccessibility values (r = 0.90, p < 0.05), as well as relative mean bioavailability values reported in healthy human groups (r = 0.98, p < 0.001). The bioaccessibility of carotenoids and vitamin E from the main dietary sources was highly variable, ranging from less than 0.1% (beta-carotene from raw tomato) to almost 100% (alpha-tocopherol from white bread). Bioaccessibility was dependent on (i) microconstituent species (lutein > beta-carotene and alpha-carotene > lycopene and alpha-tocopherol generally > gamma-tocopherol), (ii) food matrix, and (iii) food processing.  相似文献   
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Quantitative information about the amount and stability of organic carbon (OC) in different soil organic‐matter (OM) fractions and in specific organic compounds and compound‐classes is needed to improve our understanding of organic‐matter sequestration in soils. In the present paper, we summarize and integrate results performed on two different arable soils with continuous maize cropping (a) Stagnic Luvisol with maize cropping for 24 y, b) Luvic Phaeozem with maize cropping for 39 y) to identify (1) the storage of OC in different soil organic‐matter fractions, (2) the function of these fractions with respect to soil‐OC stabilization, (3) the importance and partitioning of fossil‐C deposits, and (4) the rates of soil‐OC stabilization as assessed by compound‐specific isotope analyses. The fractionation procedures included particle‐size fractionation, density fractionation, aggregate fractionation, acid hydrolysis, different oxidation procedures, isolation of extractable lipids and phospholipid fatty acids, pyrolysis, and the determination of black C. Stability of OC was determined by 13C and 14C analyses. The main inputs of OC were plant litter (both sites) and deposition of fossil C likely from coal combustion and lignite dust (only Phaeozem).  相似文献   
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603 neonatal piglets (German Landrace) were investigated for passive immunization affected by birth order, birth weight, litter size and parity. Concentrations of immunoglobulins in the blood serum of piglets on the first day of life served as measure for passive immunization. Blood samples were drawn at 12, 18 and 24 hours post partum. Quantitative measurements of immunoglobulin classes were carried out by radial immunodiffusion. There was a significant effect of birth order, because of the rapid changes in colostrum composition between onset of birth and the last piglet of each litter. The effect of birth weight was only partly significant and different for the immunoglobulin classes. There was no significant effect of litter size on passive immunization. Parity had a significant positive effect on IgG- and IgA-concentrations in sow's colostrum with litter two to six, parity 1 and 2 lead to highest IgM concentrations in the blood serum of piglets.  相似文献   
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In vitro susceptibility tests are performed to receive information for selecting the most suitable antibacterial agent. As result of in vitro susceptibility tests, the minimum inhibitory concentration (MIC) indicates bacteria as resistant or sensitive. To determine MIC, therapeutically relevant breakpoints have to be defined. Microbiological criteria, chemical and physical characteristics as well as pharmacokinetic and toxicological (tolerance) properties of the antimicrobial compounds have to be considered in the selection of the therapeutic agent in addition to clinical experiences. Using some concentration and time dependent antibiotics as examples, it is demonstrated that the above mentioned criteria are not sufficiently considered in currently defined breakpoints.  相似文献   
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In accordance with NCCLS guideline M31-A2, the DVG working group "antimicrobial resistance" developed a standard operating procedure (SOP) for the determination of the minimal inhibitory concentration (MIC) of antimicrobial agents by broth microdilution. This SOP was evaluated for its fitness for use in a national interlaboratory test. A total of 32 participating laboratories tested five strains (including two internationally accepted reference strains and three field strains representing in total three different bacterial species) three times at a one week interval each, using uniform microtitre plates. In 31 of the 32 laboratories more than 80% of MIC determinations performed yielded values in the expected range. In total 94.0% of the results were reproducible, with a lesser deviation of 4.0% from the expected values for laboratories performing MIC determination as a matter of routine (46.9%), compared to 7.9% for laboratories without such routine (53.1%). Comparing the consistency of results on the basis of the tested strains, a higher reproducibility of the results was observed for reference strains (96.1%) than for field strains (92.6%). In particular results obtained for the Streptococcus uberis field strain were afflicted with a higher error ratio (98 deviations from the expected values). Among the tested antimicrobial agents, a higher variability of results was recorded only for gentamicin with 16.7% divergent MIC determinations (mean value 6.0%). The high reproducibility of the results confirmed by this interlaboratory study underlines the robustness of the developed SOP as well as broth microdilutions as the method of choice for MIC determina tion.  相似文献   
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