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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The protease inhibitor α1-antichymotrypsin (ACT) has been suggested to be involved in the etiology of Alzheimer's disease (AD). Increased levels of ACT have been found in serum and brains of AD patients, and ACT has been proposed to regulate β-amyloid fibril formation in vitro. To gain insight into the regulation of ACT in the brain, we investigated the signal transduction pathways involved in ACT gene expression and protein synthesis in the human astrocytoma cell line U373. This cell line has previously been shown to respond with strong ACT synthesis on stimulation with interleukin-1β (IL-1β) or tumor necrosis factor-α (TNFα). Here, we describe that both IL-1β and TNFα activate the transcription factor nuclear factor-κB (NF-κB) via production of reactive oxygen intermediates resulting in ACT expression. In addition, we show that neither protein kinase C nor protein kinase A is involved in IL-1β- or TNFα-induced ACT expression. These results suggest that activation of NF-κB may be one possible cause of increased ACT levels in AD and provide a basis for the development of drugs used for the modulation of inflammatory processes occurring in AD.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The cytokine interleukin (IL)-6 has recently been demonstrated to play a role in the pathology of Alzheimer's disease (AD). The mechanisms leading to increased IL-6 levels in brains of AD patients are still unknown. Because in experimental animals ischemia increases both the level of cytokines and the extracellular concentrations of adenosine in the brain, we hypothesized that these two phenomena may be functionally connected and that adenosine might increase IL-6 gene expression in the brain. Here we show that the mixed A1 and A2 agonist 5′-(N-ethylcarboxamido)adenosine (NECA) induces an increase in IL-6 mRNA levels and protein synthesis in the human astrocytoma cell line U373 MG. The A1-specific agonists R-phenylisopropyladenosine and cyclopentyladenosine are much less potent, and the A2a-specific agonist CGS-21680 shows only marginal effects. Increased levels of mRNA are already found within 30 min after NECA treatment. The A2a-selective antagonists 8-(3-chlorostyryl)caffeine and KF17837 [(E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine], which have also some antagonistic properties at A2b receptors, and the nonspecific adenosine antagonist 8-phenyltheophylline were equipotent at inhibiting the NECA-induced increase in IL-6 protein synthesis, whereas the specific A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine is much less potent. The results indicate that adenosine A2b receptors participate in the regulation of the IL-6 gene in astrocytoma cells.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Cytokines are involved in the etiology of different disorders of the CNS. For a better understanding of their pathogenic role, we analyzed signal transduction pathways mediating the interleukin (IL)-1β-induced synthesis of IL-6 and tumor necrosis factor α (TNFα) in the human astrocytoma cell line U373 MG. Both protein kinase C and reactive oxygen intermediates (ROIs) were involved in IL-6 and TNFα gene expression by IL-1β. In contrast, protein tyrosine kinases were only necessary for expression of the IL-6 gene. Whereas activation of protein kinase A was able to induce expression of the IL-6 gene, it did not induce TNFα gene expression and was not involved in IL-1β-induced IL-6 and TNFα gene expression. Activation of the transcription factor nuclear factor-κB by IL-1β involved ROIs, whereas the IL-1β-induced activation of the transcription factor AP-1 was mediated via protein kinase C. Our findings provide the basis for the development of specific drugs for the treatment of disorders of the CNS in which cytokines play a pathogenic role.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Stimuli that evoke seizure are capable of inducing structural changes in the hippocampus. However, late-acting genes related to these changes have not been described. Administration of pentylenetetrazole (PTZ; 50 mg/kg) to rats of various ages evoked tonic-clonic seizures. Using RNA gel blot analysis we found that the level of the mRNA for microtubule-associated protein 1B (MAP1B) was robustly increased in the hippocampus of 3-month-old rats. The levels of MAP1B mRNA in hippocampus peaked at 40 h and began to decline by 72 h following PTZ treatment. Immunoblotting with anti-MAP1B antibody demonstrates the increase in content of immunoreactive proteins 40–72 h after seizure onset in the hippocampus of PTZ-treated rats. These results indicate that MAP1B is a sensitive indicator of hippocampal structural changes occurring in response to PTZ-induced seizure activity.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Interleukin-6 (IL-6) is a proinflammatory cytokine whose synthesis is induced by a variety of stimuli including interleukin-1 (IL-1), substance P (SP), and histamine. Because IL-6 has been implicated in the etiopathology of different human diseases including multiple myeloma, rheumatoid arthritis, multiple sclerosis, acquired immunodeficiency syndrome dementia complex, and Alzheimer's disease, its inhibition may be of therapeutic interest. A main demand on an effective inhibitor of IL-6 expression is that it inhibits IL-6 synthesis independently of the inducing stimulus. We therefore used human astrocytoma cells to search for signal transduction cascades and transcription factors whose inhibition suppresses IL-6 synthesis after stimulation with three different inductors, IL-1β, SP, and histamine. Whereas the antioxidant pyrrolidinedithiocarbamate was only able to inhibit IL-1β-induced IL-6 expression, inhibition of protein kinase C prevented IL-6 expression induced by all three substances. Promoter deletion analysis revealed that IL-1β-induced IL-6 expression required the transcription factor nuclear factor-κB (NF-κB), whereas SP- and histamine-induced IL-6 synthesis was essentially controlled by NF-IL-6. These findings suggest that inhibition of protein kinase C or a combinatory inhibition of NF-IL-6 and NF-κB binding are strategies to effectively suppress IL-6 synthesis. They therefore provide the basis for the development of antiinflammatory drugs used to treat disorders in which IL-6 is pathogenically involved.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 68 (1997), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Prostaglandins (PGs) and cytokines, such as interleukin-1 (IL-1) and interleukin-6 (IL-6), have been implicated in the etiopathology of various inflammatory and degenerative disorders, including Alzheimer's disease (AD) and prion diseases. Nonsteroidal antiinflammatory drugs (NSAIDs), potent inhibitors of PG synthesis, appear to be beneficial in the treatment of AD. To assess whether PGs are able to induce IL-6 synthesis in cells of the CNS, IL-6 mRNA and protein syntheses were measured in a human astrocytoma cell line after stimulation with different PGs. PGE1 and PGE2, but not PGD2 and PGF2α, led to a rapid and transient induction of IL-6 mRNA, followed by IL-6 protein synthesis. Furthermore, PGE2 potentiated IL-1β-induced IL-6 mRNA synthesis. These results are discussed with respect to the participation of PGs in neurodegenerative diseases (and its inhibition by NSAIDs) by affecting cytokine expression.
    Type of Medium: Electronic Resource
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