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  • 1
    Electronic Resource
    Electronic Resource
    Expression of Neurotrophins and Their Receptors in Primary Astroglial Cultures: Induction by Cyclic AMP-Elevating Agents (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: By northern blot analysis and ribonuclease protection assay, we observed the presence of a high level of trkB mRNA in primary brain cultures devoid of neuronal cells and highly enriched in glial fibrillary acidic protein-positive astroglial cells prepared from newborn rat cerebral hemispheres, cerebral cortex, hippocampus, and striatum. In primary astroglial cultures, the more abundant trkB transcripts code for the truncated receptor without tyrosine kinase activity; probes specific for the full-length trkB mRNA did not detect any signal in northern blot analysis. By the sensitive ribonuclease protection assay, we could show the presence of trkC mRNA in cultured astrocytes, whereas no trkA mRNA was detected. We confirmed the presence of relatively high levels of nerve growth factor and neurotrophin-3 mRNA, and very low basal level of brain-derived neurotrophic factor mRNA. Moreover, we demonstrated that another member of the neurotrophin family, neurotrophin-4, is also expressed in cultured astroglial cells. In view of the fact that many functional receptors for conventional neurotransmitters or neuropeptides present on astroglial cells may act via the adenylate cyclase system, we studied also the effect of agents able to increase the intracellular cyclic AMP concentration. A sharp increase in the trkB mRNA level was observed after treatment of primary astroglial cultures with dibutyryl cyclic AMP, 8-bromo-cyclic AMP, or the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine. On the contrary, trkC mRNA levels were unaffected by treatment with cyclic AMP-elevating agents. All the neurotrophin mRNAs examined, except neurotrophin-4, were increased by 3-isobutyl-1-methylxanthine treatment. Therefore, in cultured astroglial cells, gene expression of neurotrophins and trkB is regulated by activation of the cyclic AMP-second messenger system. This process may take part in the neuronal-glial interactions during the normal neuronal activity or after injury events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63020509.x
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  • 2
    Electronic Resource
    Electronic Resource
    GFAPβ mRNA Expression in the Normal Rat Brain and after Neuronal Injury (1999)
    Springer
    Neurochemical research 24 (1999), S. 709-714 
    Details
    ISSN: 1573-6903
    Keywords: GFAP ; gene ; alternative splicing ; intermediate filament
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract GFAPβ mRNA is an alternative transcript of the glial fibrillary acidic protein (GFAP) gene, whose transcriptional start site is located 169 nucleotides upstream to the classical GFAPα mRNA. By an RT-PCR method with primers on separate exons, we were able to confirm the presence of GFAP transcripts with a longer 5′ untraslated region in all the examined areas of rat brain and in primary cultures of astroglial cells. Northern blot analysis, using an oligoprobe specific for the 5′ region of GFAPβ, revealed a single hybridization band of 2.9 kb in all the brain regions examined and in primary cultures of astroglial cells. The availability of the quantitative Northern blot assay allowed further studies on the regulation of GFAPβ expression in vivo. Since it is well-known that neuronal brain injury is one of the most powerful inducers of GFAP, we examined the expression of GFAPα and β after a neurotoxic lesion in the rat hippocampus. Results obtained show a parallel increase in both GFAP transcripts with an identical time-course, suggesting that regulatory regions of the gene influence in similar way the rate of transcription at the two different start sites (α and β) or that a similar post-transcriptional mechanism is involved in regulating both mRNA isoforms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021016828704
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  • 3
    Electronic Resource
    Electronic Resource
    Early and late complications of endoscopic oesophageal varices sclerotherapy (1988)
    Springer
    Surgical endoscopy and other interventional techniques 2 (1988), S. 209-212 
    Details
    ISSN: 1432-2218
    Keywords: Oesophageal varices ; Endoscopic sclerotherapy ; Complications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report the complications of perendoscopic sclerotherapy observed during treatment of oesophageal varices in 104 patients and 409 sclerotherapy sessions. Complications were related to each individual session and to the aim of the treatment (therapeutic or prophylactic). Major complications occurred in 17.3% of the patients treated: 13 cases of severe bleeding and 5 of oesophageal stricture. Conservative therapy stopped haemorrhage in all but 4 patients, who died of uncontrolled bleeding (3.8%). Three oesophageal strictures recovered spontaneously, while the remaining two required endoscopic dilations. Minor complications occurred after 102/409 sessions (24.9%). Epigastric and/or retrosternal pain developed after 17.6% of the sessions, oesophageal ulcerations after 12.5%, fever after 11.7% and transient dysphagia after 3.7%. Bleeding was observed only in Child's category C patients who underwent therapeutic treatment. The risk of bleeding remained unchanged until complete eradication of varices was achieved. The incidence of minor complications did not correlate with the progression or the aim of the treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705322
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of trophic factors, released after hippocampal injury, on astroglial cell proliferation (1989)
    Springer
    Metabolic brain disease 4 (1989), S. 41-46 
    Details
    ISSN: 1573-7365
    Keywords: injury ; astrocytes ; proliferation ; trophic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An increase in astrocyte mitogenic factors and in some specific astroglial enzymatic activities after neuronal injury has been observed. Our study is concerned with the effect of the intracerebral administration of ibotenic acid (IBO) into the rat hippocampus. IBO injection causes a selective degeneration of neurons while sparing afferent fibers. We observed a transient increase in glutamine synthetase activity, a well-known astroglial marker, reaching a peak at 9–15 days after injury in lesioned hippocampus. We investigated the presence of astrocyte mitogenic factors at various times after toxin injection. Crude extracts, prepared from lesioned hippocampi 4, 9, and 14 days after IBO injection, were tested for the ability to stimulate [methyl-3H]thymidine incorporation into rat astroglial cell cultures. Crude extracts prepared 9 and 14 days after IBO injection showed a higher mitogenic activity compared to extracts prepared 4 days after lesion. Mitogenic activity of injured brain extracts was suppressed by heat inactivation (100°C for 10 min).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00999492
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of neurotrophins, GDNF, and their receptors in rat thyroid tissue (1999)
    Springer
    Cell & tissue research 295 (1999), S. 467-475 
    Details
    ISSN: 1432-0878
    Keywords: Key words Glial cell line-derived neurotrophic factor ; GDNF ; Ret ; GDNFR-α ; Brain-derived neurotrophic factor ; BDNF ; NT-3 ; NT-4 ; trk receptors ; Thyroid tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Levels of mRNA for neurotrophins (brain-derived neurotrophic factor, BDNF; neurotrophin 3, NT-3; neurotrophin 4, NT-4) and their receptors (trkA, trkB, trkC) and for glial cell line-derived neurotrophic factor (GDNF) and its receptors (ret, GDNFR-α) were measured in rat thyroid tissue by ribonuclease protection assays. In thyroid tissue the NT-3 mRNA level was threefold lower and the NT-4 mRNA level sixfold higher than those detected in adult rat hippocampus, while BDNF mRNA was undetectable. Very low levels of mRNA for truncated trkB and trkC receptors and no catalytic trkA, trkB or trkC were found. In conclusion NT-3 and NT-4, but not the corresponding functional receptors, are expressed in the thyroid tissue. Therefore, it is unlikely that these factors serve a direct local autocrine or paracrine function in thyroid cell types, and a target-derived mode of action on neurons innervating the thyroid tissue is suggested. An opposite result has been found for the neurotrophic factor GDNF: thyroid tissue showed a high level of transcripts for the GDNF receptor subunits (GDNFR-α and Ret), while GDNF mRNA was undetectable. The in situ hybridization analysis of GDNFR-α and ret mRNA revealed an interesting difference in the cell distribution of these transcripts: ret mRNA is selectively expressed in a subpopulation of cells scattered in the follicular epithelium and in the interfollicular spaces, while GDNFR-α expression is more homogeneous and widespread, including the more abundant cell type of the thyroid gland: the follicular cell. Double-labeling in situ hybridization/immunocytochemistry experiments, with a specific marker (calcitonin), showed that parafollicular cells express ret but not GDNFR-α. This differential distribution of the GDNF receptor components (GDNFR-α and ret) may reflect a peculiar biological role in intercellular communication in the thyroid gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051252
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