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  • 1
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The level and characteristics of 3′−5′-cyclic nucleotide phosphodiesterase (PDE) activity in chick dorsal root ganglion (DRG) extracts of 5-day posthatching chicken (P5) and E10 and E18 embryos were studied. At all stages, PDE activity is stimulated by calcium and calmodulin. A 5-fold increase in basal cAMP and cGMP PDE activity is evident from E10 to E18, while from E18 to P5 basal PDE activity remains constant. Ion exchange chromatography elution profile indicates that PDE1 isoforms represent the bulk of the PDE activity present. Inhibition studies were performed in order to distinguish the activity due to PDE1A, B and C. Western blot analysis using anti-mammalian PDE1A, B and C specific antibodies was also performed. Densitometric analysis of the stained bands reveals that PDE1B and PDE1C display a prominent increase between day 10 and day 18 of development (eight- and 3.6 fold, respectively) while a more limited increase (1.6- and 1.5-fold) is observed between E18 and P5; on the other hand PDE1A shows continuously increasing levels throughout development. Immunohistochemical analysis was performed with isoform specific antibodies used for western blot analysis. PDE1A immunoreactivity is found in the cytoplasm and fibers of several neurons differing in size and distributed throughout the ganglion. PDE1B staining is evident on all neurons, however, fibers appear very faintly labelled. All neurons appear stained by PDE1C antibody, although the intensity of immunostaining is always heterogeneous in different neuronal populations: no staining was evident on fibers or in non-neural cells. The distinct spatial and temporal expression patterns of PDE1 isoforms may indicate their different physiological roles in developing and mature chick DRG.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 88 (2004), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Spontaneous and potassium-induced acetylcholine release from embryonic (E12 and E18) chick dorsal root ganglia explants at 3 and 7 days in culture was investigated using a chemiluminescent procedure. A basal release ranging from 2.4 to 13.8 pm/ganglion/5 min was detected. Potassium application always induced a significant increase over the basal release. The acetylcholine levels measured in E12 explants were 6.3 and 38.4 pm/ganglion/5 min at 3 and 7 days in culture, respectively, while in E18 explant cultures they were 10.7 and 15.5 pm/ganglion/5 min. In experiments performed in the absence of extracellular Ca2+ ions, acetylcholine release, both basal and potassium-induced, was abolished and it was reduced by cholinergic antagonists. A morphometric analysis of explant fibre length suggested that acetylcholine release was directly correlated to neurite extension. Moreover, treatment of E12 dorsal root ganglion-dissociated cell cultures with carbachol as cholinergic receptor agonist was shown to induce a higher neurite outgrowth compared with untreated cultures. The concomitant treatment with carbachol and the antagonists at muscarinic receptors atropine and at nicotinic receptors mecamylamine counteracted the increase in fibre outgrowth. Although the present data have not established whether acetylcholine is released by neurones or glial cells, these observations provide the first evidence of a regulated release of acetylcholine in dorsal root ganglia.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Acetylcholinesterase (AChE) exists in various molecular forms, depending on alternative splicing of its transcripts and association with structural proteins. Tetramers of the ‘tailed’ variant (AChET), which are anchored in the cell membrane of neurons by the PRiMA (Proline Rich Membrane Anchor) protein, constitute the main form of AChE in the mammalian brain. In the mouse brain, stress and anticholinesterase inhibitors have been reported to induce expression of the unspliced ‘readthrough’ variant (AChER) mRNA which produces a monomeric form. To generalize this observation, we attempted to quantify AChER and AChET after organophosphate intoxication in the mouse brain and compared the observed effects with those of stress induced by swimming or immobilization; we also analyzed the effects of heat shock and AChE inhibition on neuroblastoma cells. Active AChE molecular forms were characterized by sedimentation and non-denaturing electrophoresis, and AChE transcripts were quantified by real-time PCR. We observed a moderate increase of the AChER transcript in some cases, both in the mouse brain and in neuroblastoma cultures, but we did not detect any increase of the corresponding active enzyme.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 206 (1965), S. 683-685 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] THE determination of nucleotide sequences in molecules of soluble, ribosomal and messenger RNAs is of considerable interest as interactions between these three types of RNA are believed to determine the specificity of protein synthesis. One procedure for the determination of nucleotide sequences of ...
    Materialart: Digitale Medien
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  • 5
    ISSN: 1573-4919
    Schlagwort(e): gp 120 ; neuron-specific enolase ; neuroblastoma ; galactosyl ceramide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract Neurological impairment is a common feature of Acquired Immunodeficiency Syndrome (AIDS); functional alterations have been reported both in central and peripheral nervous system and the Human Immunodeficiency Virus (HIV) envelope glycoprotein gp120 has been proposed as a neurotoxin acting through a calcium-dependent mechanism. On the other hand it has been reported that gp120 treatment also induce about a 20% decrease in the cerebral glucose utilization and in the cellular ATP levels. The reported observations were performed on experimental system where also non-neuronal cells where present; in order to evaluate whether a direct interaction between HIV proteins and neuronal cells takes place, we used a neuroblastoma cultures where only neuronal cells are present. We analysed the effects of gp120 on the N18TG2 neuroblastoma clone. Treatments were performed both on growing and confluent cultures. Short time treatment with gp120 of confluent cultures causes a 25% reduction in the level of neuron-specific enolase, resulting in a similar decrease of oxygen consumption. Long time exposure of growing cells also causes a reduction in cell survival. Furthermore, using a membrane-specific fluorescent probe we observed that gp120 produces an increase of membrane trafficking. These observations suggest a direct interaction between the viral envelope protein and neuronal cells, which results in an alteration of glycolytic metabolism. This alteration may be related to the neurologic impairments observed in AIDS patients.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of neuro-oncology 31 (1997), S. 123-127 
    ISSN: 1573-7373
    Schlagwort(e): cyclic nucleotide phosphodiesterase ; human neuroepithelioma ; zaprinast ; DC-TA-46 ; rolipram
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of cyclic nucleotide phosphodiesterase (PDE) inhibitors on cell proliferation of SK-N-MC human neuroepithelioma cell line was studied. Clonal density experiments in the presence of 100 μM rolipram and zaprinast showed respectively 27% and 91% inhibition. The effects of PDE inhibitors were then investigated on crude cell extracts; the calculated IC50 were 32 μM for zaprinast and 16 nM for DC-TA-46; the latter inhibitor was used instead of rolipram for itshigher efficacy. Dose-response experiments in clonal density conditions showed IC50 of 5 μM and 1.8 μM in the presence respectively of zaprinast and rolipram. These data show that both inhibitors are effective in reducing cell growth, although the response was quantitatively different.
    Materialart: Digitale Medien
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