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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 280 (1988), S. 103-107 
    ISSN: 1432-069X
    Keywords: Arachidonic acid ; Retinoids ; Fatty acids ; Keratinocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the effect of etretin (Ro 10-1670), the active metabolite of the widely used antipsoriatic drug etretinate (Ro 10-9359), on the incorporation and release of arachidonic acid in human skin keratinocytes. During 24-h culture, radioactive 14C-arachidonic acid was avidly incorporated into the cellular lipids of the keratinocytes. When the cells were cultured for another 48 h in fresh medium, 8.8%±0.3% of the incorporated radioactivity was released from the cells. The presence of etretin (10-8 M to 10-5 M) in the medium stimulated the release of radiolabel. With 10-5 M etretin in the culture medium, 13.0%±0.4% of the incorporated radioactivity was released, and this was accompanied by decreased labelling of phosphatidylethanolamine. This suggests that phosphatidylethanolamine may be an important source of the released arachidonic acid. Etretin pretreatment reduced the incorporation of 14C-arachidonic acid into diacylglycerols, triacylglycerols, and cholesteryl esters. Pretreatment for 48 h with 10-5 M etretin reduced subsequent 14C-arachidonic acid incorporation into nonphosphorus lipids from a mean total of 8.2%±0.2% to 3.2%±0.1% (p〈0.001). These findings suggest that etretin interferes with the esterification of arachidonic acid into nonphosphorus lipids. Etretin was also found to cause changes in the fatty acid composition of keratinocytes. Following 48 h culture with etretin, the percentage amount of the fatty acids belonging to the n3 series was increased whereas that of palmitic acid (16:0) and palmitoleic acid (16:1n7) was decreased. In conclusion, our study suggests that etretin in therapeutical concentrations affects fatty acid metabolism in human keratinocytes in culture.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: RQ ; Insulin ; Glucose ; Lactate ; Pyruvate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary RQ, plasma insulin, blood glucose, lactate and pyruvate were measured in six fit, normal subjects during a series of exercise and rest experiments with and without sucrose ingestion. Subjects exercised on a bicycle ergometer for 50 min of every hour for 6 h at about 47% of the group's average maximal aerobic capacity. In the resting experiments, the subjects sat for 6 h in an armchair. A solution containing 100 g of sucrose was ingested at the beginning of the fourth hour during the sucrose experiments. Ingestion of sucrose caused a significant increase in RQ, plasma insulin, blood glucose, lactate and pyruvate in both exercise and rest experiments. Insulin, lactate and pyruvate concentrations rose higher during rest after sucrose ingestion than during exercise. The time courses of the changes in RQ, insulin, glucose, lactate and pyruvate after sucrose ingestion, suggest that glucose entering the cell during rest is immediately oxidized, while during work there is some delay in the oxidation of glucose.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: RQ ; C14O2 ; Lactate ; Pyruvate ; Carbohydrate Utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four well-trained male subjects worked for periods of 6 h on bicycle ergometers at work loads requiring about 47% of their maximal aerobic capacity. In one series of studies they received only water; in a second series they received 100 g of sucrose containing 100 μc U-C14-labelled sucrose at the beginning of the fourth hour of work. In a third series of experiments, the same subjects received 100 g of non-labelled sucrose at the beginning of the fourth hour. During the experiment without U-C14-labelled sucrose, blood samples were withdrawn and analysed for glucose, lactate and pyruvate content. Data from C14O2 recovery in expired air showed a good correlation with the amount of carbohydrate oxidized during the sucrose experiment. Peak values for the respiratory exchange ratio showed the same time response as those observed for the C14O2 in the expired air. It is concluded that the observed rise in RQ after sucrose ingestion, under the conditions studied, is of metabolic origin, resulting from a complete conversion of pyruvate to CO2.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 278 (1986), S. 441-444 
    ISSN: 1432-069X
    Keywords: Keratinocyte ; Arachidonic acid ; UV irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following labeling of human keratinocytes in culture for 48 h with 14C-arachidonic acid (800,000 cpm), 86.8±0.5% (mean±SEM) of the radioactivity was incorporated into the cells. Two hours after exposure to UVB irradiation at doses up to 392 mJ/cm2 of erythemally effective (EE) UVB irradiation, only slight changes in the distribution of arachidonic acid could be detected. However, 24 h after irradiation the release of arachidonic acid into the culture medium was significantly increased. The distribution of arachidonic acid was also changed: there was a considerable loss in the amount of radioactivity associated with phosphatidylethanolamine. With doses up to 174 mJ/cm2 (EE) of UVB, the decrease in the labeling of phospholipids was accompanied by an increased arachidonic acid content in the nonphosphorus lipids, especially in the triacylglycerols. Following a high dose of UVB (392 mJ/cm2, EE), a substantial release of label was detected, but the labeling of triacylglycerols was unaltered. The present study suggests that in human keratinocytes UVB irradiation induces the release of arachidonic acid from the cellular lipids and that the major source of the released arachidonic acid is phosphatidylethanolamine.
    Type of Medium: Electronic Resource
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