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  • 1
  • 2
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The carbon assimilation efficiency and the internal composition of the chlorophyte Dunaliella viridis have been studied under conditions of current (0.035%) and enriched (1%) levels of CO2, with and without N limitation (supplied as nitrate). Results show that both photosynthesis and growth rates are enhanced by high CO2, but the strategy of acclimation also involves the light harvesting machinery and the nutritional metabolism in an N supply dependent manner. D. viridis carried out a qualitative rather than a quantitative acclimation of the light harvesting system leading to increased PSII quantum yields. Total internal C decreased as a consequence of either active growth or organic carbon release to the external medium. The latter process allowed photosynthetic electron transport to proceed at higher rates than under normal CO2 conditions, and maintained the internal C:N balance in a narrow range (under N sufficiency). N limitation generally prevented the effects of high CO2, with some exceptions such as the photosynthetic O2 evolution rate.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of salt lake research 4 (1995), S. 223-232 
    ISSN: 1573-8590
    Keywords: Dunaliella viridis ; subsidiary energy ; turbulence ; carbon supply ; photosynthetic efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Turbulence is known to enhance growth in microalgae. We studied the possible effects of the extra inorganic carbon supplied to the cultures when air bubbling is the source of turbulence. A set of experiments was carried out to separate the effects of the subsidiary action of agitation on growth from those due to possible carbon enrichment from air CO2 when air bubbling was the source of mixing. It was found that air bubbling does not induce an increase of the concentration of inorganic carbon in HCO 3 − -enriched growth media, and that no differences appear between air-bubbled and CO2-free air-bubbled cultures. On the other hand, photosynthetic O2 was accumulated in the medium in non-mixed cultures, which showed higher respiration and lower photosynthetic rates, probably due to photoinhibition induced by oversaturation of O2. Growth rate, maximal cell density and photosynthetic efficiency were higher in aerated cultures than in non-aerated ones.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The factors that can influence the outcome of orthotopic liver transplantation (OLT) are numerous. The purpose of this study was to determine the effects of recipient preoperative factors on patient mortality. Between April 1986 and April 1998 a total of 600 OLTs were performed in our institution. We retrospectively reviewed our first 203 consecutive primary adult OLTs with at least 4 years of follow-up. A case-control comparison was performed between survivors and nonsurvivors, and differences in recipient variables were studied for their correlation with patient mortality. A logistic regression analysis was also performed. Mortality was significantly increased among those with fulminant hepatic failure (FHF) (66.6%, p= 0.003), primary cancer (63.1%, p= 0.018), females (46.1%, p= 0.043), encephalopathy grade IV (72.7%, p= 0.012), recipients under respiratory support (69.2%, p= 0.031), and ABO-incompatible transplants (80%, p= 0.05). FHF, primary cancer, and female gender were the only variables that had a significant association with mortality in the logistic regression analysis. A higher incidence of prolonged respiratory support, bacterial and fungal infections, pneumonia, and chronic rejection contributed to the lower outcome observed in females. These results stress the need for continuous evaluation of the selection criteria of candidates for OLT suffering from primary cancer and FHF. The impact of recipient gender on mortality warrants further analysis but suggests that in the future more attention must be paid to the influence of this factor on the final outcome of OLT.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-2568
    Keywords: cholesterol embolism ; atheroembolism ; gastrointestinal tract ; intestinal performation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 3 (1991), S. 319-327 
    ISSN: 1573-5176
    Keywords: Dunaliella viridis ; growth ; salinity ; temperature ; nitrogen concentration ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of a strain ofD. viridis has been studied in batch culture under different combinations of temperature, salinity and nitrogen concentrations. Changes in these variables have a significant effect on cell division, biomass production, cell volume and pigment yield. This strain grows optimally at 1 M NaCl and 30 °C. Increasing salinity up to 4 M NaCl leads to a significant decrease of cell division rate and maximal population; growth at lower temperature decreases the rate of division of the cells but increases maximal cell density. Pigment yield decreases with increasing salinity and increases with increasing temperature. Nitrogen concentration has a large effect on total cell biomass and pigment production, but not on cell division rate. Saturation of growth occurs at 5 mM NO 3 − ; higher concentration (e.g. 10 mM) leads to a decrease of maximal cell density and photosynthetic pigment content.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5176
    Keywords: Cyanobacterium ; Spirulina platensis ; Arthrospira ; CO2 ; organic carbon ; nitrogen ; photosynthesis ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The consequences of the addition of CO2 (1%) in cultures of S. platensis are examined in terms of biomass yield, cell composition and external medium composition. CO2 enrichment was tested under nitrogen saturating and nitrogen limiting conditions. Increasing CO2 levels did not cause any change in maximum growth rate while it decreased maximum biomass yield. Protein and pigments were decreased and carbohydrate increased by high CO2, but the capability to store carbohydrates was saturated. C:N ratio remained unchanged while organic carbon released to the external medium was enhanced, suggesting that organic carbon release in S. platensis is an efficient mechanism for the maintenance of the metabolic integrity, balancing the cell C:N ratio in response to environmental CO2 changes. CO2 affected the pigment content: Phycocyanin, chlorophyll and carotenoids were reduced in around 50%, but the photosynthetic parameters were slightly changed. We propose that in S. platensis CO2 could act promoting degradation of pigments synthetised in excess in normal CO2 conditions, that are not necessary for light harvesting. Nitrogen assimilation was significantly not affected by CO2, and it is proposed that the inability to stimulate N assimilation by CO2 enrichment determined the lack of response in maximum growth rate.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 2 (1990), S. 309-317 
    ISSN: 1573-5176
    Keywords: Dunaliella viridis ; net photosynthesis ; temperature ; nitrogen concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic behaviour ofDunaliella viridis has been studied under a combination of three variables: irradiance (0–900 μmol m−2 s−1), temperature (15, 23, 31, 38, 42 °C) and nitrogen concentration (0.05, 0.5, 1.5, 5, 10 mM NO 3 - ) at a salinity of 2 M NaCl. The highest rates of photosynthesis have been found at 31 °C and a nitrate concentration of 10 mM. There exists a synergistic effect between temperature and nitrogen availability on the photosynthesis ofD. viridis; under nitrogen deficiency oxygen evolution is low, even null at high temperature. The interaction between these two variables of control occurs in a multiplicative way. There is also a general increase in photosynthetic pigments following the increase in nitrogen concentration in the culture medium. The normalization of net photosynthesis data in relation to chlorophylla shows that nitrogen concentration makes an indirect control of the photosynthetic rate ofD. viridis through the variation of pigment concentration. The study of the photosynthetic parameters shows that the slope (α) of the curves of photosynthesis and the light-saturated photosynthesis (Pmax) are controlled by more than one variable, including temperature and nitrogen availability.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 3 (1991), S. 319-327 
    ISSN: 1573-5176
    Keywords: Dunaliella viridis ; growth ; salinity ; temperature ; nitrogen concentration ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of a strain ofD. viridis has been studied in batch culture under different combinations of temperature, salinity and nitrogen concentrations. Changes in these variables have a significant effect on cell division, biomass production, cell volume and pigment yield. This strain grows optimally at 1 M NaCl and 30 °C. Increasing salinity up to 4 M NaCl leads to a significant decrease of cell division rate and maximal population; growth at lower temperature decreases the rate of division of the cells but increases maximal cell density. Pigment yield decreases with increasing salinity and increases with increasing temperature. Nitrogen concentration has a large effect on total cell biomass and pigment production, but not on cell division rate. Saturation of growth occurs at 5 mM NO 3 − ; higher concentration (e.g. 10 mM) leads to a decrease of maximal cell density and photosynthetic pigment content.
    Type of Medium: Electronic Resource
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