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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In the developing rat brain, the enzymatic formation of prostaglandin D2 from prostaglandin H2 increased 60-fold from day 12 of gestation to birth. The activity still rose gradually to the highest level (90 nmol/min/g wet tissue) at day 7 after birth. The activities of prostaglandin E2 and F2α synthetases in rat brain were highest at gestational age 19 days (30 nmol/min/g wet tissue) and at gestational age 14 days (15 nmol/min/g wet tissue), respectively. The specific activity of NADP-dependent 15-hydroxy-prostaglandin D2 dehydrogenase in rat brain was highest at the earliest gestational age we examined (day 12 of gestation), The specific bindings of prostaglandin D2 and E2 to the crude mitochondrial fraction of rat brain were observed from day 16 of gestation and increased to day 7 after birth. Although the activities of the enzymes responsible for prostaglandin metabolism were unchanged postmaturationally, the maximal concentrations of the binding sites on the synaptic membrane for both prostaglandins D2 and E2 decreased with constant affinity to less than one-sixth with age from 1 week to 24 months after birth. These results indicate that prostaglandins may play important roles during maturation and aging in rat brain.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Various prostaglandins (PGs) (10 nM-30 μM) were added to NG108–15 cells in culture, and changes in the levels of intracellular cyclic GMP and Ca2+ were investigated. Exposure of the cells to PGF2α, PGD2, and PGE2 (10 μM) transiently increased the cyclic GMP content 7.5-, 3.9-, and 3.1-fold, respectively. Furthermore, the increased levels of cyclic GMP correlated well with the rise in cytosolic free Ca2+ concentrations induced by the PGs. Other PGs (10 μM), including metabolites and synthetic analogs, which had no effect on intracellular Ca2+, failed to increase the cyclic GMP content in the cells. When extracellular Ca2+ was depleted from the culture medium, the PG-induced increase in cyclic GMP level was almost completely abolished. In addition, treatment of the cells with quin 2 tetraacetoxymethyl ester dose-dependently inhibited the PG-induced cyclic GMP formation. The increase in cyclic GMP content caused by treatment of the cells with a high K+ level (50 mM) was completely blocked by voltage-dependent Ca2+ entry blockers, such as verapamil (10 μM), nifedipine (1 μM), and diltiazem (100 μM); however, the PG (10 μM)-induced increase in cyclic GMP content was not affected by such Ca2+ entry blockers. These findings indicate that PG-induced cyclic GMP formation may require the rise in intracellular Ca2+ level and that the voltage-dependent Ca2+ channels may not be involved in the PG-induced rise in Ca2+ content.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The accumulation of inositol phosphates (IPs) in response to prostaglandins (PGs) was studied in NG108-15 cells preincubated with myo-[3H]inositol. As a positive control, bradykinin caused accumulation of IPs transiently at an early phase (within 1 min) and continuously during a late phase (15-60 min) of incubation in the cells. PGD2 and PGF2adid not significantly cause the accumulation of IPs at an early phase but significantly stimulated inositol bisphosphate (IP2) and inositol monophosphate (IP1) formation at a late phase of incubation. The maximum stimulation was obtained at 〈10−7M concentrations of these PGs. the levels being three-and twofold for IP2 and IP1 respectively. 9α, 11 β-PGF2 has a slight effect but PGE2 and the metabolites of PGD2 and PGF2α have no effect up to 10−6M. The effects of PGD2 and PGF2α were not additive, but the effect of each PG was additive to that of bradykinin at a late phase of incubation.Inositol 1-monophosphate was mainly identified in the stimulation by 10−5 M PGD2 and 10−5MPGF2a, whereas both inositol 1-monophosphate and inositol 4-monophosphate were produced in the stimulation by 10−5M bradykinin. Depletion of extracellular Ca2+ diminished the stimulatory effect of PGD2 and PGF2α and late-phase effect of bradykinin, but simple Ca2+ influx into the cells by high K+, ionomycin, or A23187 failed to cause such late-phase effects. These results suggest that PGD2 and PGF2α specifically stimulate hydrolysis of inositol phospholipids.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 55 (1990), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fluorometric method and a rapid paper test method were developed for differentiating fresh from frozen-thawed fish. The methods were based on measurement of the activity of neutral β-N-acetylglucosa-minidase. This enzyme, found in fish red blood cells, was inactive in intact cells but was activated when cells were disrupted by freezing and thawing. Both methods were applicable for testing most common edible fish prior to filleting and required about 20 min using a UV-lamp.
    Type of Medium: Electronic Resource
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