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  • 1
    Digitale Medien
    Digitale Medien
    Effect of Antioxidants on Cholesterol Oxidation in Spray-dried Egg Yolk during Extended Ambient Storage (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 67 (2002), S. 0 
    Details
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: : Equimolar amounts of butylated hydroxyanisole, ascorbyl palmitate or a tocopherol blend were added to liquid yolk and spray-dried. One-g samples were stored in the dark at ambient temperature for 36 mo, then evaluated using gas chromatography. The tocopherol blend and BHA inhibited 7-ketocholesterol production. No significant differences were observed between the control and the various antioxidant treatments for the production of other cholesterol oxides. In contrast to the results of a previously conducted accelerated study, the added antioxidant levels were insufficient to significantly reduce cholesterol oxidation in spray-dried egg yolk held for an extended period of time, and additional means of inhibition may be required.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2621.2002.tb08828.x
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  • 2
    Digitale Medien
    Digitale Medien
    Towards the ecology of hyperthermophiles: biotopes, new isolation strategies and novel metabolic properties (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 24 (2000), S. 0 
    Details
    ISSN: 1574-6976
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Ecological studies have shown that water-containing terrestrial, subterranean and submarine high-temperature environments harbor a great diversity of hyperthermophilic prokaryotes, growing fastest at temperatures of 80°C or above. The investigations included cultivation, isolation and detailed analysis of these hyperthermophiles as well as in situ 16S rRNA gene sequence analysis and in situ hybridization studies. For a safe and fast isolation of novel hyperthermophiles from mixed cultures, a new, plating-independent isolation technique was developed, based on the use of a laser microscope (‘optical tweezers’). This method, combined with 16S rRNA gene sequence analysis and whole-cell hybridization using fluorescently labelled oligonucleotide probes, even allows the recovery of pure cultures of phylogenetically predicted organisms harboring novel 16S rRNA gene sequences. In their natural habitats, hyperthermophiles form complex food webs, consisting of primary producers and consumers of organic material. Their metabolic potential includes various types of aerobic and anaerobic respiration and different modes of fermentation. In hydrothermal and geothermal environments, hyperthermophiles have important ecological functions in biogeochemical processes. Members of the Sulfolobales are able to mobilize heavy metals from sulfidic ores like pyrite or chalcopyrite. Biomineralization processes of hyperthermophiles include the formation of magnetite from iron or the precipitation of arsenate as realgar, a reaction performed by a novel hyperthermophile that was isolated from Pisciarelli Solfatara, Naples, Italy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1574-6976.2000.tb00562.x
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  • 3
    Digitale Medien
    Digitale Medien
    Constitutional supercooling and the growth of 200 nm Bi–Sb wire array composites (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 1337-1343 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Bi1−xSbx (x(approximate)0.1) alloy crystals present a high thermoelectric figure of merit at T(approximate)100 K. The alloys are difficult to grow successfully and require special techniques to avoid constitutional supercooling and the resulting segregation. We present a study of the growth of 200 nm wire arrays of Bi–Sb by high-pressure injection of the melt of the alloy in a porous template. We find that the concentration of Sb in the nanowires is much lower than the composition of the starting alloy and discuss the results in terms of a model of constitutional supercooling in restricted geometries. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1490159
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  • 4
    Digitale Medien
    Digitale Medien
    Step-induced magnetic-hysteresis anisotropy in ferromagnetic thin films (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3150-3153 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We investigate the quasistatic magnetic hysteresis of ferromagnetic thin films grown on a vicinal substrate, using Monte Carlo simulations within a two-dimensional XY model. Intrinsic in-plane anisotropy is assigned to surface sites according to their local symmetry. The simulated hysteresis loops show a strong anisotropy: the coercive field is the largest when the external field is along the step direction and vanishes when the external field is perpendicular to the step direction. In general, the coercivity increases with increasing step density, but displays a more complex dependence on film thickness. The simulations also suggest that the mechanism for the magnetization reversal is coherent rotation. These results are in good agreement with experiments. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1433179
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  • 5
    Digitale Medien
    Digitale Medien
    Direct comparison of mechanical and electro-optic responses of a low Tg photorefractive doped polymer (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1710-1712 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The temperature dependence of the electro-optic responses in a low glass transition temperature (Tg) photorefractive polymer was investigated using an ellipsometric technique. The sample was composed of a carbazole functionalized polysiloxane doped with a push–pull chalcone derivative. The results provide information on the orientational dynamics of the chromophores doping the polymer host. For this purpose, the electro-optic response is directly compared, for different temperatures above Tg, to dynamic shear compliance measurements characterizing the mechanical macroscopic behavior of the material. We demonstrate here that these orientational processes are entirely ruled by the mechanical properties of the material. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1428788
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  • 6
    Digitale Medien
    Digitale Medien
    Epidermal growth factor and keratinocyte growth factor differentially regulate epidermal migration, growth, and differentiation (2000)
    Oxford, UK : Blackwell Science Inc
    Wound repair and regeneration 8 (2000), S. 0 
    Details
    ISSN: 1524-475X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Various growth factors such as epidermal growth factor and keratinocyte growth factor have been reported to promote wound closure and epidermal regeneration. In the present study epidermis reconstructed on de-epidermized dermis was used to investigate the effects of epidermal growth factor and keratinocyte growth factor on keratinocyte proliferation, migration and differentiation. Our results show that epidermal growth factor supplemented cultures share many of the features which are observed during regeneration of wounded epidermis: a thickening of the entire epidermis, an enhanced rate of proliferation and migration, and an increase in keratin 6, keratin 16, skin-derived antileukoproteinase, involucrin and transglutaminase 1 expression. The increase in transglutaminase 1 protein is accompanied by an increase in the amount of active transglutaminase 1 enzyme. Surprisingly no increase in keratin 17 is observed. Prolonging the culture period for more than two weeks results in rapid senescence and aging of the cultures. In contrast, keratinocyte growth factor supplemented cultures have a tissue architecture that is similar to healthy native epidermis and remains unchanged for at least 4 weeks of air-exposure. The rate of proliferation and the expression of keratins 6, 16 and 17, skin-derived antileukoproteinase, involucrin and transglutaminase 1 is similar to that found in healthy epidermis and furthermore keratinocyte migration does not occur. When the culture medium is supplemented with a combination of keratinocyte growth factor and a low concentration of epidermal growth factor, skin-derived antileukoproteinase, involucrin and keratins 6, 16 and 17 expression is similar to that found in cultures supplemented with keratinocyte growth factor alone and in healthy epidermis. Only high transglutaminase 1 expression remains similar to that observed in cultures supplemented with epidermal growth factor alone. Our results show that the regulation of keratinocyte growth, migration and differentiation depends on the availability of these growth factors. Epidermal growth factor may play a dominant early role in wound healing by stimulating keratinocyte proliferation and migration while keratinocyte growth factor may play a role later in the repair process by stabilizing epidermal turnover and barrier function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1524-475x.2000.00192.x
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  • 7
    Digitale Medien
    Digitale Medien
    Delegation to civil servants in parliamentary democracies (2000)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of political research 37 (2000), S. 0 
    Details
    ISSN: 1475-6765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Politikwissenschaft
    Notizen: Abstract. This article reviews institutional arrangements that cabinet ministers and other political actors employ to influence civil servant behavior in parliamentary democracies. I then discuss how unlike other theories of bureaucratic structure, the principal–agent framework can be employed to generate testable hypotheses about systematic cross–national variation in delegation instruments. I also offer an empirical illustration of the approach, one that examines the relationship between cabinet turnover and delegation strategies on health policy. The analysis underlines the need to be cautious about making claims concerning the impact of political factors (like cabinet instability) and institutional factors (like cabinet decision–making rules) on delegation outcomes without first examining how these factors influence delegation strategies themselves.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1475-6765.00519
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  • 8
    Digitale Medien
    Digitale Medien
    Assessment of Stereoselectivity of Trimethylphenylalanine Analogues of δ-Opioid [D-Pen2,D-Pen5]-Enkephalin (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract : [D-Pen2,D-Pen5]-Enkephalin (DPDPE) is an enzymatically stable δ-opioid receptor-selective peptide, which was modified by the trimethylation of the Phe4 residue to give β-methyl-2′,6′-dimethylphenylalanine (TMP), resulting in four conformations : (2R,3S)-β-Phe-DPDPE, (2R,3R)-β-Phe-DPDPE, (2R,3S)-β-Phe-DPDPE, and (2S,3R)-β-Phe-DPDPE. Synthesis was by solid-phase techniques using enantiomerically pure amino acids to give the four optically pure diastereoisomer peptides. The potency and selectivity (δ- versus μ-opioid receptor) were evaluated by radioreceptor binding in rat brain, with a μ/δ ratio decrease for all TMP conformations, compared with the parent compound (DPDPE). Octanol/buffer distribution analysis showed enhanced lipophilicity of all TMP forms, with a sixfold enhancement associated with (2S,3S)-TMP. In situ vascular perfusion in anesthetized rats showed a 1.6-fold (p 〈 0.01) increase in the ratio of brain uptake for (2S,3S)-TMP and a 1.5-fold (p 〈 0.01) decrease in uptake for (2R,3R)-TMP. Saturability of (2S,3S)-TMP was shown (p 〈 0.01) against 100 μM unlabeled DPDPE, showing a shared nondiffusionary transport system. P-glycoprotein affinity was shown in situ for the parent and (2S,3S)-TMP (p 〈 0.01). Protein binding capacity of the TMP compounds in rat plasma and in situ mammalian bovine serum albumin-Ringer showed (2R,3S)-TMP and (2S,3R)-TMP with the lowest degree of protein binding (p 〈 0.01), and (2S,3S)-TMP and (2R,3R)-TMP with comparable affinities to DPDPE. Analgesia, via intravenous administration, showed significantly reduced (p 〈 0.01) end effect and time course for (2R,3R)-TMP, (2R,3S)-TMP, and (2S,3R)-TMP as compared with DPDPE. These results demonstrate that topographical modification in a conformationally restricted peptide can significantly modulate potency and receptor selectivity, binding capacity, enzymatic stability, lipophilicity, P-glycoprotein affinity, and blood-brain barrier permeability, resulting in a change of bioavailability, and thereby provides insight for future peptide drug design.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0750424.x
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  • 9
    Digitale Medien
    Digitale Medien
    Protein Binding of NADH on Chemical Preconditioning (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract : Chemical preconditioning, an emerging neuroprotective strategy described in recent years, results in preserved energy metabolism during hypoxia via yet unknown mechanisms. The hypoxic increase of NADH content is attenuated by preconditioning. The goal of the present study was to investigate whether attenuation of the hypoxic NADH increase is due to a shift between free and protein-bound NADH. NADH in solution has a fluorescence maximum at 469.2 nm. In untreated mouse hippocampal slices, λcontrol onset is 456.2 ± 5.3 nm in CA1 (mean ± SD ; p 〈 0.01 vs. solution) and 454.6 ± 6.1 nm in CA3 [p 〈 0.01 vs. solution, not significant (NS) to λcontrol onset in CA1]. In slices prepared from animals pretreated in vivo with 20 mg/kg 3-nitropropionate, λpreconditioning onset is 439.2 ± 5.0 nm (p 〈 0.001 vs. control) in CA1 and 434.2 ± 6.4 nm in CA3 (p 〈 0.001 vs. control ; NS to λpreconditioning onset in CA1). In controls, the fluorescence maximum shifts to λcontrol hypoxia 458.2 ± 1.3 nm in CA1 (NS vs. onset) and 456.0 ± 3.6 nm in CA3 (NS vs. onset). On preconditioning with 3-nitropropionate, λpreconditioning hypoxia shifts to 446.4 ± 4.3 nm in CA1 (p 〈 0.03 vs. onset) and 438.6 ± 6.9 nm in CA3 (p 〈 0.03 vs. onset). Posthypoxic decay of free and protein-bound NADH is diminished after preconditioning. We conclude that the free NADH level is reduced on an increase of hypoxic tolerance by chemical preconditioning. Reduction of free NADH content is maintained during hypoxia after preconditioning.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0750329.x
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  • 10
    Digitale Medien
    Digitale Medien
    Expression of small proline rich proteins in neoplastic and inflammatory skin diseases (2000)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 143 (2000), S. 0 
    Details
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background The formation of the cornified cell envelope (CE) during the late stages of epidermal differentiation is essential for epidermal barrier function and protects the body against environmental attack and water loss. Formation of the CE involves the replacement of the plasma membrane by cross-linkage of precursor proteins such as involucrin, small proline rich proteins (SPRR) and loricrin. In normal epidermis, SPRR1 is restricted to appendages, SPRR2 is also expressed in interfollicular areas, while SPRR3 is completely absent; the latter is most abundant in oral epithelium. This differential expression indicates an important part for SPRRs in specific barrier requirements, and reflects their importance in the biomechanical properties of the CE. Objectives We report here on the expression of SPRR1, SPRR2 and SPRR3 in a wide range of cutaneous neoplastic and inflammatory diseases. Methods We used immunohistochemistry; in addition, Northern blot analysis of malignant tumours was performed. Results Increased suprabasal expression of SPRR1 and SPRR2, but no SPRR3 expression, was noted in inflammatory dermatoses with orthokeratotic and parakeratotic squamous differentiation. By contrast, differentiating epidermal tumours such as Bowen’s disease, keratoacanthoma and squamous cell carcinoma expressed SPRR3. Conclusions As SPRRs were originally cloned on the basis of their expression in ultraviolet light-irradiated keratinocytes, the expression of SPRR3 in actinic lesions is of interest, and might serve as a diagnostic tool.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2133.2000.03768.x
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