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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Somatostatin (SS) and neuropeptide Y (NPY) are coproduced in a subpopulation of neurons that are selectively resistant to NMDA neurotoxicity. We have previously reported that quinolinic acid (QUIN), an NMDA receptor agonist, augments SS mRNA in cultured fetal rat cortical neurons. This study examines coregulation of SS and NPY by QUIN and NMDA in cultured cortical neurons and compares the effects of these agents with those of forskolin and phorbol 12-myristate 13-acetate (PMA), known to activate SS and NPY gene transcription by protein kinase A- and protein kinase C-dependent mechanisms. In addition, transcriptional regulation of the SS gene was investigated by acute transfection of cortical cultures with an SS promoter-chloramphenicol acetyltransferase (CAT) construct. QUIN and NMDA displayed dose-dependent fourfold augmentation of levels of mRNA for SS but not for NPY. In contrast, forskolin and PMA increased both SS and NPY mRNA levels. QUIN- and NMDA-mediated induction of SS mRNA was blocked by the NMDA receptor antagonist (−)-2-amino-5-phosphonovaleric acid and displayed regional brain specificity because it was not observed in fetal hypothalamic cell cultures. In time course studies, the effects of QUIN/NMDA on SS mRNA occurred after a latency of 8 h, indicating a delayed effect. Cortical cells transfected with pSS-750 CAT showed three- to fourfold stimulation of CAT activity with forskolin but not by QUIN or NMDA. These data reveal a dose-dependent, tissue-specific, NMDA receptor-mediated stimulation of SS but not NPY mRNA. Such stimulation of SS gene expression does not require activation of the protein kinase A or protein kinase C signaling pathways, is not transcriptionally mediated, and is likely posttranscriptional, as also suggested by the delay in SS mRNA induction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Increasing evidence suggests that apolipoprotein D (apoD) could play a major role in mediating neuronal degeneration and regeneration in the CNS and the PNS. To investigate further the temporal pattern of apoD expression after experimental traumatic brain injury in the rat, male Sprague-Dawley rats were subjected to unilateral cortical impact injury. The animals were killed and examined for apoD mRNA and protein expression and for immunohistological analysis at intervals from 15 min to 14 days after injury. Increased apoD mRNA and protein levels were seen in the cortex and hippocampus ipsilateral to the injury site from 48 h to 14 days after the trauma. Immunohistological investigation demonstrated a differential pattern of apoD expression in the cortex and hippocampus, respectively : Increased apoD immunoreactivity in glial cells was detected from 2 to 3 days after the injury in cortex and hippocampus. In contrast, increased expression of apoD was seen in cortical and hippocampal neurons at later time points following impact injury. Concurrent histopathological examination using hematoxylin and eosin demonstrated dark, shrunken neurons in the cortex ipsilateral to the injury site. In contrast, no evidence of cell death was observed in the hippocampus ipsilateral to the injury site up to 14 days after the trauma. No evidence of increased apoD mRNA or protein expression or neuronal pathology by hematoxylin and eosin staining was detected in the contralateral cortex and hippocampus. Our results reveal induction of apoD expression in the cortex and hippocampus following traumatic brain injury in the rat. Our data also suggest that increased apoD expression may play an important role in cortical neuronal degeneration after brain injury in vivo. However, increased expression of apoD in the hippocampus may not necessarily be indicative of neuronal death.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nutrition 9 (1989), S. 395-416 
    ISSN: 0199-9885
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Unsteady flow to a large-diameter well has been analyzed by a discrete kernel approach, taking well storage into consideration. The variation of drawdown with time has been obtained at the well and inside the aquifer. The validity of the new method has been verified by comparing the drawdown at the well with the drawdown given by Papadopulos and Cooper (1967). The aquifer contribution to discharge at various times has been estimated.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1920
    Keywords: Key words Cyst ; arachnoid ; Spinal cord compression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Imaging studies in eight patients with surgically-confirmed spinal arachnoid cysts were analyzed retrospectively. All patients had preoperative MRI of the spine and seven preoperative myelography with postmyelographic CT. In all cases the correct diagnosis could be made preoperatively on the basis solely of MRI. The diagnosis could also be established from myelography and postmyelographic CT in six of the seven cases. In one case myelography and CT simply demonstrated an intradural extramedullary mass.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 238 (2000), S. 352-358 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Purpose: To develop a model for analyzing the immune response after xenogenic human fetal retinal pigment epithelium (HFRPE) transplantation. Materials and methods: Pure sheets of HFRPE cells were isolated and attached to poly (dl-lactide-co-glycolide) polymer films and HFRPE spheroids were formed. The spheroids were transplanted into the subretinal space of New Zealand albino rabbits and were observed for 5 months. Bare polymer films were transplanted into the subretinal space of Dutch Belted pigmented rabbits, serving as control. Results: The polymer film was bioegraded within 3 weeks in the subretinal space. No signs of inflammation in the retina or choroid were observed. The HFRPE spheroids were easily transplanted into the subretinal space. The immune response was followed with ophthalmoscopy. Light microscopy indicated a localized immune response in the transplanted area in which the retina and the choroid were infiltrated with immune cells. This infiltration was denser in the choroid. Conclusions: HFRPE spheroid transplantation may be utilized as a model for studying the xenogenic immune response after HFRPE transplantation. This model may also have applications in evaluating the role of immune suppressive agents in preventing rejection after HFRPE transplantation.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 29 (2000), S. 765-773 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract NPC1 is a member of a family of polytopic membrane-bound proteins with sterol-sensing domains. Inactivating mutations of NPC1 are responsible for most cases of Niemann-Pick type C disease, whose hallmark is progressive neurodegeneration. The precise molecular mechanisms whereby defective NPC1 function leads to neurodegeneration are unknown. In the brain, we have previously found NPC1 to localize predominantly within perisynaptic astrocytic processes. Here we have mapped the regional distribution of NPC1 in the monkey brain. Dense NPC1 immunoreactivity was observed in telencephalic structures, including the cerebral neocortex, hippocampus, caudate nucleus and putamen, whilst light immunostaining was observed in diencephalic structures, including the globus pallidus, thalamus and hypothalamus. Light staining was also generally observed in the midbrain, pons, medulla oblongata and cerebellum, except the inferior olive, which was densely stained. By light microscopy, only a few indistinctly labeled cell bodies were observed even within densely labeled regions, where most of the immunoreactivity appeared to be due to the large numbers of labeled cellular processes. On electron microscopy, these processes were identified as glial, and not neuronal. The astrocytic localization of NPC1 was further confirmed by double labeling for NPC1 and GFAP. The regional pattern of NPC1 expression suggests that areas normally expressing low levels of the NPC1 protein are more susceptible to neuronal degeneration in Niemann-Pick type C disease.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 237 (1999), S. 934-939 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Background: The suppressive effect of human fetal retinal pigment epithelium (HFRPE) on the activation of human CD4+ and CD8+ T-cells was evaluated in vitro. · Methods: Pure populations of CD4+ and CD8+ T-cells were isolated from human peripheral blood-derived buffy coats by negative immunomagnetic selection. The purity of the cells was examined by flow cytometry using anti-CD3-FITC, anti-CD4-FITC, anti-CD8-PE, and anti-CD20-PE mAbs. HFRPE cells were isolated from fetal eyes and pure cultures were obtained. The effect of normal or IFN-γ-activated HFRPE cells at early (P3) or late (P6) passages on the activation of CD4+ and CD8+ T-cells was assessed in two different T-cell activation assays. In both activation models anti-CD3 mAb (OKT3) provided the antigen-specific signal. The secondary signal for the activation of CD4+ and CD8+ T-cells was provided with anti-CD18 mAb (TS1/18) and anti-CD28 mAb (9.3) in the first and the second assay respectively. Cross-linking of these soluble mAbs was performed with sheep-anti-mouse IgG-coated latex beads. The T-cell activation was determined by cell proliferation measured by [3H]thymidine incorporation. In each activation assay T-cells were incubated with HFRPE cells in a ratio of T-cells to HFRPE of 1:1 or 1:4. · Results: CD4+ and CD8+ T-cells were activated by cross-linking CD3 and CD18 in the first assay (CD3/CD18) and CD3 and CD28 in the second assay (CD3/CD28). In both assays HFRPE inhibited the activation of CD4+ and CD8+ T-cells. IFN-γ-activated HFRPE cells totally suppressed the T-cell activation at a 1:1 ratio. This suppressive effect was weaker at lower cell ratios. Some donor variation was observed in the inhibition at the lower cell ratios, especially for the inhibition of CD8+ T-cell activation with anti-CD3/CD18. The passaging of HFRPE cells did not alter their suppressive effect on CD4+ and CD8+ T-cells. · Conclusions: HFRPE cells suppressed the activation of both CD4+ and CD8+ T-cells in vitro. These findings suggest that RPE-induced immune suppression may play a significant role in maintaining immune privilege in the subretinal space.
    Type of Medium: Electronic Resource
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