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  • 1
    Electronic Resource
    Electronic Resource
    Breast cancer, estrogen, soy genistein, and other dietary factors: Towards an understanding of their mechanistic interactions (2005)
    Bingley : Emerald
    Nutrition & food science 35 (2005), S. 35-42 
    Details
    ISSN: 0034-6659
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purpose - The purpose of this literature review is to examine underlying mechanisms through which soy may affect breast cancer risk. Design/methodology/approach - The approach taken is to summarize the emerging mechanisms of how isoflavones, such as genistein, interact with processes leading to breast cancer. Findings - The key finding of this analysis is that these mechanisms include a multitude of contrasting effects of genistein on estrogenic and non-estrogenic signaling pathways controlling cell growth. Furthermore, several of these mechanisms are also regulated by additional dietary factors, such as omega-3 fatty acids (found e.g. in fish) and various other phytochemicals (factors found generally in plant-based foods). The available mechanistic information supports (i) a potent effect of dietary factors on cell growth and (ii) a synergistic effect of different dietary components, such as soy, fish, and plant-based foods. Practical implications - In conclusion, the practical implication of this analysis is the conclusion that the mechanistic information available at this time does not support a recommendation for an isolated increase in soy to decrease breast cancer risk. Originality/value - This article should be of value for health care providers, nutritionists, and consumers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00346650510579126
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  • 2
    Electronic Resource
    Electronic Resource
    Breast cancer, Asian diet, and soy genistein - a matter of all or nothing? (2005)
    Bingley : Emerald
    Nutrition & food science 35 (2005), S. 28-34 
    Details
    ISSN: 0034-6659
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purpose - The purpose of this literature review is to examine the relationship between soy consumption and breast cancer risk since soy isoflavones, such as genistein, are currently discussed as possible breast cancer-fighting agents in the Asian diet. Design/methodology/approach - The approach taken is to summarize and evaluate the available literature on the effect of soy, and the Asian diet, on breast cancer risk. Findings - A key finding of the current analysis is that the effect of genistein depends strongly on dosage and developmental stage during which exposure occurs. The overall conclusion and value of this comprehensive analysis is that the available evidence does not support a recommendation for increased soy consumption as a breast cancer-preventing agent against the background of a Western diet. Instead, additional general components of the Asian diet, such as fish and plant-based food, may be involved in lowering breast cancer risk. Research limitations/implications - A limitation to drawing final conclusions at this time is that further research is clearly needed to better understand the overall effect of soy and other dietary factors. Practical implications - The practical implication for health care providers, nutritionists, and consumers is therefore a recommendation to avoid isoflavone supplements and enhanced soy consumption alone at this time without an increased intake of the other Asian diet components. Originality/value - This review arrives at new conclusions about the connection between soy and breast cancer that are summarized under findings and should be valuable for health care providers, nutritionists, and consumers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00346650510579135
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  • 3
    Electronic Resource
    Electronic Resource
    The remarkable role of nutrition in learning and behaviour (2005)
    Bingley : Emerald
    Nutrition & food science 35 (2005), S. 258-263 
    Details
    ISSN: 0034-6659
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purpose - The purpose of this review is to examine the effect of nutrition on mental functions of children and adolescents. Design/methodology/approach - The approach taken is to evaluate published research on key dietary factors, including recent, rigorously designed supplementation studies. Findings - The result of this analysis is that nutrition has potent effects on brain function. It is concluded that protein, iron, iodine, and the consumption of breakfast all impact on a child's learning capability and behaviour. Moreover, recent research has identified additional, potent roles of micronutrients, such as essential fatty acids, minerals, and vitamins, in the prevention of learning and behavioural disorders. Among the latter, this review focuses particularly on attention deficit hyperactivity disorder. Research limitations/implications - While several controlled supplementation trials with supplementation are now available, the limitation of the present analysis is that more large-scale trials are needed before final conclusions can be reached. Practical implications - The practical implication of this review for health-care providers, nutritionists, teachers, and parents at this time is that enough promising evidence has be accumulated to warrant a recommendation to include adequate levels of minerals, vitamins, essential fatty acids, and other nutrients in children's diets to improve learning and behaviour. Originality/value - This review is unique in its comprehensive nature and provides a synopsis of the power of diet in influencing learning and behavior for professionals and parents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00346650510605658
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  • 4
    Electronic Resource
    Electronic Resource
    Close relationship between the state of the xanthophyll cycle pigments and photosystem II efficiency during recovery from winter stress (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 96 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The potential involvement of the xanthophyll cycle in photoprotection of overwintering evergreen plants was investigated. Leaves from five evergreen species. Pseudotsuga menziesii, Pinus panderosa, Euonyums kiautschovicus. Mahonia repens and Malva neglecta, were collected from the field predawn during winter and transferred to the laboratory where chlorophyll fluorescence emission as well as the chlorophyll and carotenoid composition were ascertained periodically for 4.5 days. Leaves and needles from all species were found to have retained large amounts of the xanthophyll cycle pigments zeaxanthin and antheraxanthin, and they exhibited sustained low values of the intrinsic efficiency of photosystem II (PSII; measured as the ratio of variable to maximal fluorescence, Fv/Fm) upon collection. The increase in PSII efficiency was biphasic, with a rapid phase (requiring several hours) and a slow phase (requiring several days). Changes in the conversion state of the xanthophyll cycle were found to correlate with increases in PSII efficiency in both phases, with the latter phase involving large increases in both Fm (maximal fluorescence) and Fo (minimal fluorescence) throughout the period of recovery. The relationship between Fm quenching (expressed as nonphotochemical or Stern-Volmer quenching [NPQ] of Fm, i.e. Fm/ Fm–1) and Fo quenching (Fo/Fo–1) was linear, as expected for changes in xanthophyll cycle-dependent energy dissipation in the antenna complexes. Furthermore, the relationship between Fv/Fm and NPQ during recovery followed the theoretical relationship predicted for changes in the rate constant for energy dissipation in the antenna complexes. This fit between the theoretical relationship and the actual data indicates that all changes in NPQ or Fv/Fm can be accounted for by changes in this rate constant. The results suggest a role for the photoprotective xanthophyll cycle-dependent dissipation process in the lowered efficiency of PSII observed in coldstressed evergreen plants in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb00228.x
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  • 5
    Electronic Resource
    Electronic Resource
    Carotenoid composition and down regulation of photosystem II in three conifer species during the winter (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 92 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The carotenoid composition of the needles of three conifer species. Ponderosa pine (Pinus ponderosa). Douglas fir (Pseudotsuga menziesü) and blue spruce (Picea pun—gens). growing in full sunlight was found to differ between the summer and the winter, with higher levels of lutein and the carotenoids of the xanthophyll cycle and lower levels of α-carotene being present during the winter. In addition, the extent of the de-epoxidation of violaxunthin to antheraxanthin and zeaxanthin at midday was greater during the winter than during the summer. The latter two carotenoids were also found to be retained at high levels overnight on cold days during the winter. Associated with the retention of antheraxanlhin and zeaxanthin were sustained depressions of photosystem II (PSII) efficiency. These decreases in photo system II efficiency were accompanied by changes in chlorophyll fluorescence characteristics that are indicative of increased levels of energy dissipation in the chlorophyll pigment bed. Sustained depressions in PSII efficiency are commonly interpreted as “photoinhibitton”. We therefore suggest that low temperature-induced photo inhibition in these conifers during the winter was due to a down regulation of photosystem II that involved sustained xanthophyll cycle-associated energy dissipation. Furthermore, the predawn conversion state of the xanthophyll cycle responded rapidly to day to day variation in temperature. Being less epoxidized on colder days and more epoxidized on both previous and subsequent warmer days. Such flexibility in the response of the santhophyll cycle to changes in temperature may be important in the regulation and protection of the photosynthetic apparatus of such evergreen plants in a climate that experiences relatively rapid changes in temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb08835.x
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  • 6
    Electronic Resource
    Electronic Resource
    Using chlorophyll fluorescence to assess the fraction of absorbed light allocated to thermal dissipation of excess excitation (1996)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 98 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the present study we explored the possibility of assessing the allocation of photons absorbed by photosystem II (PSII) antennae to thermal energy dissipation and photosynthetic electron transport in leaves of several plant species under field conditions. Changes in chlorophyll fluorescence parameters were determined in situ over the course of an entire day in the field in sun-exposed leaves of two species with different maximal rates of photosynthesis, Helianthus annuus (sunflower) and Vinca major. Leaves of Vinca minor (periwinkle) growing in a deeply shaded location were also monitored. We propose using diurnal changes in the efficiency of open PSII centers (F′v/F′m) in these sun and shade leaves to (a) assess diurnal changes in the allocation of absorbed light to photochemistry and thermal energy dissipation and, furthermore, (b) make an estimate of changes in the rate of thermal energy dissipation, an analogous expression to the rate of photochemistry. The fraction of light absorbed in PSII antennae that is dissipated thermally (D) is proposed to be estimated from D = 1-F′v/F′m, in analogy to the widely used estimation of the fraction of light absorbed in PSII antennae (P) that is utilized in PSII photochemistry from P = F′v/F′m× qP (where qP is the coefficient for photochemical quenching; Genty, B., Briantais, J.-M. & Baker, N. R. 1989. Biochim. Biophys. Acta 990: 87-92). The rate of thermal dissipation is consequently given by D × PFD (photon flux density), again in analogy to the rate of photochemistry P × PFD, both assuming a matching behavior of photosystems I and II. Characterization of energy dissipation from the efficiency of open PSII centers allows an assessment from a single set of measurements at any time of day; this is particularly useful under field conditions where the fully relaxed reference values of variable or maximal fluorescence needed for the computation of nonphotochemical quenching may not be available. The usefulness of the assessment described above is compared with other currently used parameters to quantify nonphotochemical and photochemical chlorophyll fluorescence quenching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1996.980206.x
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  • 7
    Electronic Resource
    Electronic Resource
    Lichtstreß und Lichtschutz bei Pflanzen (1989)
    Springer
    Naturwissenschaften 76 (1989), S. 262-267 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368635
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  • 8
    Electronic Resource
    Electronic Resource
    Photosynthesis Harvesting sunlight safely (2000)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 403 (2000), S. 371-374 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] By harnessing the Sun's energy, photosynthesis provides the energy-rich and structural molecules (as well as oxygen) on which most life on this planet depends. Photosynthetic organisms, including green plants, have mastered the challenge of harvesting sunlight efficiently at one moment and then ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35000315
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  • 9
    Electronic Resource
    Electronic Resource
    Seasonal differences in xanthophyll cycle characteristics and antioxidants in Mahonia repens growing in different light environments (1998)
    Springer
    Oecologia 116 (1998), S. 9-17 
    Details
    ISSN: 1432-1939
    Keywords: Key words Antioxidants ; Cold acclimation ; Mahonia repens ; Photoprotection ; Xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigated differences between summer and winter in photosynthesis, xanthophyll cycle-dependent energy dissipation, and antioxidant systems in populations of Mahonia repens (Lindley) Don growing in the eastern foothills of the Colorado Rocky Mountains in deep shade, full exposure, and under a single-layered canopy of Pinus ponderosa (partially shaded). In summer, increasing growth irradiance (from deep shade to partial shade to full exposure) was associated with increased xanthophyll cycle-dependent energy dissipation in PSII and an increased capacity to detoxify reactive reduced oxygen species, as measured by increases in the activities of ascorbate peroxidase, superoxide scavenging, glutathione reductase, and monodehydroascorbate reductase, as well as increases in leaf ascorbate and glutathione content. Leaves of exposed and partially shaded plants exhibited decreased capacities for photosynthetic O2 evolution in winter compared to summer, while in the deeply shaded plants this parameter did not differ seasonally. Seasonal differences in the levels of antioxidants generally exhibited an inverse response to photosynthesis, being higher in winter compared to summer in the exposed and partially shaded populations, but remaining unchanged in the deeply shaded population. In addition, total pool size and conversion state of the xanthophyll cycle were higher in winter than in summer in all populations. These trends suggest that both xanthophyll cycle-dependent energy dissipation in PSII and the capacity to detoxify reactive reduced oxygen species responded to the level of excess light absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013823
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of high light on the efficiency of photochemical energy conversion in a variety of lichen species with green and blue-green phycobionts (1990)
    Springer
    Planta 180 (1990), S. 400-409 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Chlorophyta ; Cyanobacteria ; Desiccation ; Lichens ; Light stress ; Photoinhibition in phycobionts ; Phycobiont
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure to high light induced a quantitatively similar decrease in the rate of photosynthesis at limiting photon flux density (PFD) and of photosystem II (PSII) photochemical efficiency, FV/FM, in both green and blue-green algal lichens which were fully hydrated. Such depressions in the efficiency of photochemical energy conversion were generally reversible in green algal lichens but rather sustained in blue-green algal lichens. This greater susceptibility of blue-green algal lichens to sustained photoinhibition was not related to differences in the capacity to utilize light in photosynthesis, since the light-and CO2-saturated rates of photosynthetic O2 evolution were similar in the two groups. These reductions of PSII photochemical efficiency were, however, largely prevented in lichen thalli which were fully desiccated prior to exposure to high PFD. Thalli of green algal lichens which were allowed to desiccate during the exposure to high light exhibited similar recovery kinetics to those which were kept fully hydrated, whereas bluegreen algal lichens which became desiccated during a similar exposure exhibited greatly accelerated recovery compared to those which were kept fully hydrated. Thus, green algal lichens were able to recover from exposure to excessive PFDs when thalli were in either the hydrated or desiccated state during such an exposure, whereas in blue-green algal lichens the decrease in photochemical efficiency was reversible in thalli illuminated in the desiccated state but rather sustained subsequent to illumination of thalli in the hydrated state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198792
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