bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons
Authors: Ekström P. A. R. , Bergstrand H. , Edström A. 
Published: May 2005

AbstractThe effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons were tested. Regeneration of crush‐injured nerves for 8 days in serum‐free medium was inhibited by staurosporine (100 nM) and H‐7 (100 μM), which are both known to inhibit protein kinase C. With the use of a compartmented culture system it could be shown that H‐7 exerted both local (outgrowth region) and central (ganglia) effects, the latter being more pronounced. The local effects could be due to reduction of Schwann cell proliferation by H‐7. Immunohisto‐chemistry demonstrated the presence of protein kinase C in neuronal cell bodies but not in axonal processes. Proliferation of Schwann cells was accompanied by increased protein kinase C immunoreactivity at the site of injury. H‐7 caused a selective inhibition in the incorporation of radioactive phosphate into one 74 kDa protein of both ganglia and nerve but also a more general decrease in protein labelling. The results show that protein phosphorylations, possibly mediated by protein kinase C, are involved in regeneration‐related mechanisms operating at both local and central levels in the adult frog sciatic sensory axons.
Interferon‐γ‐Like immunoreactivity in sensory neurons may influence the replication of sendai and mumps viruses
Authors: Eneroth A. , Andersson T. , Olsson T. , Örvell C. , Norrby E. , Kristensson K. 
Published: May 2005

AbstractRat dorsal root ganglia in tissue culture, which contain an interferon‐γ (IFN‐γ)‐like immunoreactive subpopulation of neurons, were infected with paramyxoviruses. Sendai virus caused a substantial neuronal lysis, while the RW strain of mumps virus caused a much less pronounced nerve cell loss. Early during infection, the subpopulation of IFN‐γ‐like immunoreactive neurons was less susceptible to mumps virus. Virus antigen was rapidly lost from surviving IFN‐γ‐like positive neurons infected with Sendai virus, while this remarkable self‐curing effect occurred in both nerve cell populations at later time points after mumps virus infection. By quantitative enzyme‐linked immunosorbent assay (ELISA) technique, increased levels of “neuronal IFN‐γ” were recorded at 10 hr and 30 hr after infection with Sendai and mumps virus, respectively. This study indicates a role for the neuronal IFN‐y‐like molecule in determining the outcome of a viral infection in sensory ganglia.
Focal, extracellular recording of slow miniature junctional potentials at the mouse neuromuscular junction
Authors: Vautrin J. , Kriebel M. E. 
Published: May 2005

AbstractMiniature endplate potentials (MEPPs) with slow rising phase can be attributed either to burst of transmitter releases or to distortion of conduction from remote releasing sites. The spontaneous activity of neuromuscular junctions recorded extracellularly at mouse diaphragms using sharp electrodes was analyzed to test these two hypotheses. The miniature Junctional potentials (MEJPs) frequencies observed intracellularly as compared to MEPP frequency measured intracellularly in controls indicate that most events recorded extracellularly are induced by the presence of the electrode. All types of MEPPs (bell‐MEPPs, skew‐MEPPs, slow‐, and giant MEPPs) previously described with intracellular recording methods (Vautrin and Kriebel, Neuroscience 41:71–88, 1991) were observed extracellularly and showed similar characteristics. This means that the presynaptic and postsynaptic zones that generate these synaptic events are restricted within areas of a few micrometers squared of synaptic contact. Long rise times of extracellularly recorded synaptic spontaneous events may be explained by multiple transmitter releases at intervals shorter than the rise time of individual events, which postsynaptic responses fuse into a single peak.
Implication of glucocorticoid receptors in the stimulation of human glioma cell proliferation by dexamethasone
Authors: Langeveld C. H. , van Waas M. P. , Stoof J. C. , Suianto W. , de Kloet E. R. , Wolbers J. G. , Heimans J. J. 
Published: May 2005

AbstractDexamethasone is frequently used in the therapy of brain tumor patients. We investigated the effect of dexamethasone on the proliferation of three short‐term and four established human glioma cell lines in vitro, using a microculture tetrazolium assay to determine growth rates. In one short‐term culture and in one established cell line dexamethasone consistently stimulated the proliferation in concentration‐dependent way. The proliferation was maximally enhanced at a concentration of approximately 0.1 μM. In these two cell lines a relatively high level of glucocorticoid receptors was present, whereas low levels of glucocorticoid receptors were found in the other cell lines. In addition, we demonstrated that the stimulatory effects of dexamethasone on the proliferation of the glioma cell lines can be antagonized by the antiglucocorticoid RU38486. The results demonstrate unequivocally that the glucocorticoid receptor plays a role in the growth stimulating effect of dexamethasone.
Subcellular distribution of ubiquitin–protein conjugates in the hippocampus following transient ischemia
Authors: Hayashi T. , Takada K. , Matsuda M. 
Published: May 2005

AbstractUbiquitin–protein conjugates in the hippocampus were analyzed by immunoblotting with a monoclonal anti‐ubiquitin antibody. In the CA1 region, Triton X‐100 insoluble ubiquitin–protein conjugates increased after 24 hr following 20 min of ischemia. When the total hippocampi were fractionated subcellularly, ubiquitin–protein conjugates increased in the particulate, especially in the mitochondrial fraction. The ubiquitin–protein conjugates were solubilized by SDS, or were partially solubilized by urea. The results indicate that insoluble ubiquitin–protein conjugates increase after ischemia.
Nerve growth factor‐stimulated calcium uptake into PC12 cells: Uniqueness of the channel and evidence for phosphorylation
Authors: Nikodijevic B. , Guroff G. 
Published: May 2005

AbstractNerve growth factor stimulates the uptake of radioactive calcium into PC12 cells. This stimulation is inhibited by low concentrations of dideoxyforskolin or staurosporine, and by high concentrations of nifedipine or cadmium. On the other hand, neither dideoxyforskolin nor staurosporine inhibited the stimulation of calcium uptake caused by BK‐8644 or adenosine triphosphate (ATP). Nickel inhibited only the effect of ATP on calcium uptake, and actually stimulated the effects of either BK‐8644 or nerve growth factor.Down‐regulation of L‐calcium channels by BK‐8644 blocked the subsequent stimulation of calcium uptake by this agent, but not the stimulation by nerve growth factor. Conversely, pre‐treatment of the cells with nerve growth factor inhibited the subsequent stimulation of calcium uptake by nerve growth factor, but not the stimulation by BK‐8644. The effects of BK‐8644 and nerve growth factor on calcium up‐take were additive, as were the effects of nerve growth factor and ATP.Phosphatase 2A inhibited the effect of nerve growth factor on calcium uptake, but did not influence the action of BK‐8644. On the other hand, cal‐cineurin inhibited the effect of BK‐8644 on calcium uptake, but potentiated the action of nerve growth factor. Calmidazolium or fluphenazine also inhibited the effect of nerve growth factor on calcium uptake, but okadaic acid stimulated it.A comparison of the effects of these inhibitors on the actions of various calcium channel agonists shows that the channels on which the action of nerve growth factor is exerted are different than either the L‐type calcium channels or the ATP‐activated calcium channels. These data also indicate that the action of nerve growth factor is mediated by phosphorylation of some component of the nerve growth factor‐sensitive calcium channel.
Expression of heat shock genes (hsp70) in the rabbit spinal cord: Localization of constitutive and hyperthermia‐inducible mRNA species
Authors: Manzerra P. , Brown I. R. 
Published: May 2005

AbstractWe have previously reported that hyperthermia induces the expression of a heat shock gene in the rabbit brain (Sprang and Brown, Mol Brain Res 3:89–93, 1987). Striking regional and cell type differences in the pattern of induction of the hsp70 mRNA were noted. Tissue injury also induces the rapid induction of hsp70 mRNA in the mammalian brain (Brown et al., Neuron 2:1559–1564, 1989). In the present study, in situ hybridization with 35S‐Iabelled riboprobes specific for constitutive and inducible hsp70 mRNA species was employed to investigate the effect of fever‐like temperatures on hsp70 gene expression in the rabbit spinal cord. Expression of constitutive hsp70 mRNA was detected in large motor neurons of both control and hyperthermic animals. Within 1 hr after hyperthermia, a massive induction of inducible hsp70 mRNA was noted in fibre tracts of the spinal cord, a pattern consistent with a strong glial response to heat shock. Induction was not observed in the large motor neurons.
Expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and wallerian degeneration
Authors: Vedeler C. A. , Conti G. , Bannerman P. , Pleasure D. 
Published: May 2005

AbstractNorthern blots were used to examine the expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and Wallerian degeneration. Steady state levels of FcRIII (1.4 kb) and Crry (1.9 and 2.1 kb) mRNAs were higher in adult rat nerves than in 6 day and 21day postnatal rat nerves, indicating that the expression of these receptors is developmentally regulated. The FcRIII and Crry cDNA probes also hybridized with total RNA from 3 day old rat Schwann cells and from adult rat peritoneal macrophages. The size of the FcRIII mRNA expressed by cultured Schwann cells (1.6 kb) differed from that expressed by peritoneal macrophages (1.4 kb); the two may be splice variants of one transcript or products of related genes. Peritoneal macrophages contained approximately 100 times higher FcRIII mRNA levels than Schwann cells. In contrast, steady state levels of both 1.9 and 2.1 kb Crry mRNAs were similar in cultured Schwann cells and macrophages. Nerve transection induced a generalized increase in the level of sciatic FcRIII mRNA (1.4 kb) 3 days post‐surgery, whereas he level of Crry mRNA was increased only in the nerve segment immediately to the cut. The increase of FcRIII mRNA that occurred in Wallerian degeneration was most likely due to infiltration of macro‐phages, as FcRIII mRNA‐positive macrophages were demonstrated in the degenerating nerves by in situ hybridization. FcRIII mRNA‐positive macrophages were not found in normal nerve. The functions of FcRIII and Crry in peripheral nerves are uncertain, but they may be of significance in phagocytosis, antibody‐dependent cellular cytotoxicity, and in local immune regulation.
Inhibition of nerve growth factor‐stimulated neurite outgrowth by methylamine‐modified α2‐macroglobulin
Authors: Koo P. H. , Liebl D. J. 
Published: May 2005

Abstractα2‐Macroglobulin (α2M) is a rather ubiquitous protein in extracellular spaces of mammals. It is an inhibitor of endopeptidases, can be modified by aliphatic amines, and combines with a number of hormones/cytokines such as β‐nerve growth factor (NGF) [Koo PH, Stach RW (1989): J Neurosci Res 22:247]. The objective of this study is to compare the NGF‐binding properties of methylamine‐modified human α2M (MA‐α2M) versus normal α2M and their effects on the biological activity of NGF and neurite extension by embryonic chicken dorsal root ganglia. As determined by gel filtration, polyacrylamide gel electrophoresis, and equilibrium binding studies, these two forms of α2M are similar in their binding affinities, with MA‐α2M binding about twice as much NGF as normal α2M. Both normal α2M and MA α2M combine noncovalently with NGF, and prior modification of α2M is unnecessary for the binding to occur. In contrast to normal α2M, MA‐α2M potently inhibits the biological activity of NGF and exerts a dose‐dependent inhibition on the NGF‐stimulated neurite outgrowth by embryonic chicken dorsal root ganglia in culture. The inhibitory effect of MA‐α2M can be overcome by higher NGF concentrations, but is irreversible at lower NGF concentrations. Trypsin‐modified α2M combines covalently and noncovalently with more NGF than normal α2M but has very little neurite inhibitory activity. The mechanism of inhibition by MA‐α2M is discussed.
Function and evolution in the NGF family and its receptors
Authors: Ebendal T. 
Published: May 2005

AbstractThe gene family of neurotrophins includes nerve growth factor (NGF), brain‐derived neurotrophic factor (BDNF), neurotrophin‐3 (NT‐3), and neurotrophin‐4 (NT‐4). Recently, neurotrophin‐5 (NT‐5), a possible mammalian homologue to NT‐4 described in the frog Xenopus, has been cloned in man and rat. The neurotrophins stimulate survival and differentiation of a range of target neurons by binding to cell surface receptors. The structure of NGF has recently been clarified from crystallographic data. The similarities between the different neurotrophins are substantial with the variable regions, giving specificity to each of the family members, being localized to some exposed loop regions. Low‐affinity binding (Kd of 10−9 M) of all tested neurotrophins is mediated via a 75 K glycoprotein (LNGFR) that has been cloned and characterized. A 140 K tyrosine protein kinase encoded by the proto‐oncogene trk has been found to bind NGF with high affinity (Kd of 10−11 M) and to evoke the cellular neurotrophic responses. In addition, a protein encoded by the trk‐related gene trkB has been shown to bind BDNF. Recently, a third member of the trk family, trkC, has been cloned and demonstrated to function as a high‐affinity receptor for NT‐3. The expression of trk and LNGFR mRNA are co‐localized in the rat brain to the medial septal nucleus and the nucleus of Broca's diagonal band containing the NGF‐responsive magnocellular cholinergic neurons projecting to hippocampus and cerebral cortex. In sharp contrast, the pattern of expression of trkB is widely spread in many areas of the cortex as well as lateral septum. The trkB protein might serve general functions in large areas of the cortex. Site‐directed mutagenesis and expression of recombinant chimaeric neurotrophin proteins have made it possible to localize a likely region for the interaction between NGF and the LNGFR. This region could be altered, resulting in the total loss of LNGFR binding by the mutant NGF protein without affecting the binding to the trk receptor which was sufficient for the full biological activity. Cladistic analysis of likely phylogenies within the neurotrophins shows BDNF and NT‐4 to be most closely related whereas NGF may be the sister group to NT‐3, BDNF, and NT‐4. Neurotrophins offer obvious clinical possibilities for treatment of neurodegenerative diseases. © 1992 Wiley‐Liss, Inc.
Astrocyte cultures from human embryonic brain: Characterization and modulation of surface molecules by inflammatory cytokines
Authors: Aloisi F. , Borsellino G. , Samoggia P. , Testa U. , Chelucci C. , Russo G. , Peschle C. , Levi G. 
Published: May 2005

AbstractAstrocyte‐enriched cultures were established upon passaging of primary cultures from the myelencephalon and mesencephalon of 7–9‐week‐old human embryos. Immunocytochemical analysis showed that third‐fourth passage cultures were composed of a highly enriched population of proliferating, epithelioid cells, up to 90% of which expressed glial fibrillary acidic protein (GFAP); no macrophages and very few fibroblasts (>2%) were present. GFAP expression and proliferation declined upon further culturing in serum‐containing medium but could be transiently reinduced by growing the cells in a serum‐free chemically defined medium. Large numbers of GFAP+ astrocytes were obtained from each embryo and could be stored frozen and recultured.Using flow cytometric analysis, human astrocyte cultures were examined for basal and cytokine [interferon‐γ (IFN‐γ), interleukin‐1β (IL‐1β), and tumor necrosis factor‐α (TNF‐α)]‐induced expression of molecules that may be involved in astrocyte‐T‐lymphocyte interactions. Cultured human astrocytes spontaneously expressed major histocompatibility complex (MHC) class I antigens and variable levels of MHC class II; MHC class I levels were increased upon IFN‐γ and TNF‐α treatment, whereas MHC class II antigens were induced on most of the astrocytes by IFN‐γ. Among the molecules involved in antigen‐independent interactions between T lymphocytes and target cells, lymphocyte function‐associated molecule‐3 (LFA‐3) was spontaneously expressed by most cultured human astrocytes, whereas intercellular adhesion molecule‐1 (ICAM‐1) was present at variable levels in non‐stimulated astrocytes and was greatly induced by IFN‐γ, TNF‐α, and IL‐1β. In this study we also show that the above cytokines upregulate astroglial expression of adhesion molecules of the integrin family (VLA‐1, VLA‐2, and VLA‐6) that may be involved in astrocyte‐extracellular matrix interaction and play a role in the astrocyte reactive changes occurring at sites of brain injury and inflammation.The human astrocyte cultures developed here represent a useful in vitro model to further investigate mechanisms involved in bidirectional communication between central glia and cells of the immune system. © 1992 Wiley‐Liss, Inc.
Myelin protein expression in dissociated superior cervical ganglia and dorsal root ganglia cultures
Authors: Brunden Kurt R. , Ding Y. , Hennington B. S. 
Published: May 2005

AbstractSchwann cells of the adult rat superior cervical ganglia (SCG) synthesize negligible levels of the major myelin glycoprotein, P0, in vivo. This suggests that the sympathetic axons of the SCG are deficient in one of more components involved in the regulation of myelin protein expression. Here we have compared the ability of neurites from neonatal rat SCG and embryonic rat dorsal root ganglia (DRG) to induce Schwann cell expression of myelin proteins after growth in culture using a serum‐free medium. Steady‐state P0 mRNA levels in the SCG and DRG culture paradigms were determined with a sensitive polymerase chain reaction (PCR) assay that amplified cDNA produced by reverse transcription of mRNA. This semiquantitative assay showed a linear response to increasing amounts of P0 and actin mRNA and required substantially less cellular RNA than typical hybridization techniques. Using the PCR assay, we found that SCG cultures contained significantly lower amounts of P0 mRNA than did DRG cultures. To further confirm that SCG cultures have negligible expression of myelin proteins, immunoblot analyses were done to examine the steady‐state levels of both P0 and myelin basic protein. While nonmyelinating DRG cultures had readily detectable amounts of these myelin‐specific proteins, neither could be demonstrated in the SCG cultures. The data indicate that SCG neurites lack one or more signals needed to induce myelin protein expression. Employing SCG and DRG cultures in comparative biochemical studies should prove useful in identifying the axonal molecule(s) involved in the regulation of myelin protein expression. © 1992 Wiley‐Liss, Inc.
Expression of the Class III β‐tubulin isotype in developing neurons in culture
Authors: Ferreira Adriana , Caceres A. 
Published: May 2005

AbstractThe expression of the class III β‐tubulin isotype was studied in cultured brain neurons by means of a monoclonal antibody (TuJ1). The results obtained indicate that during early axonal outgrowth most of the class III β‐tubulin is not incorporated into microtubules, a phenomenon which is also observed under conditions which alter the rate and extent of the neurite outgrowth response. On the other hand, a dramatic increase in its incorporation into microtubules is observed after the neurons have differentiated their neurites as axons and dendrites. In addition, the appearance of colchicine‐resistant microtubules containing this isotype, a phenomenon which occurs late in neurite development, is highly coincident with the appearance of stable microtubules containing high molecular weight microtubule‐associated proteins (MAPs). This pattern is different from that of the accumulation and incorporation of other β‐tubulin isotypes into microtubules. Taken collectively, our results indicate that differences exist in the in vivo utilization of tubulin isotypes in developing brain neurons and suggest that the class III β‐tubulin isotype is not a primary factor involved in the regulation of microtubule assembly during early neurite out‐growth, but that it may be important for maintaining further neurite elongation and/or determining some unique binding property of MAPs to specific microtubule subsets. © 1992 Wiley‐Liss, Inc.
Effects of bright artificial light on monoamines and neuropeptides in eight different brain regions compared in a pigmented and nonpigmented rat strain
Authors: Humpel C. , Neudorfer C. , Philipp W. , Steiner H. J. , Haring C. , Schmid K. W. , Schwitzer J. , Saria Alois 
Published: May 2005

AbstractSeasonal affective disorder is a form of depression which recurs at the same time of the year. Exposure to bright artificial light at a dose of 2,500 lux is used to treat seasonal affective disorders. We exposed a pigmented (Brown Norway) and a nonpigmented (Sprague‐Dawley) rat strain with bright artificial light for 21 days at two doses (2,500 and 6,100 lux) and analyzed dopamine, dihydroxyphenyl‐acetic acid, 5‐hydroxytryptamine (5‐HT), and 5‐hydroxyindole‐acetic acid (5‐HIAA) by high performance liquid chromatography (HPLC) and electrochemical detection in eight different brain regions. Furthermore, we measured tissue levels of substance P (SP), neurokinins (NK), vasoactive intestinal polypeptide (VIP), calcitonin gene‐related peptide (CGRP), and neuropeptide Y (NPY) with radioimmunoassay. Our data obtained with light microscopy show that bright artificial light at both doses induced a massive destruction of photoreceptors in the retina of albino rats but not of the pigmented rat strain. Retinal lesion of photoreceptors resulted in increased tissue levels of all measured neuropeptides except SP in the hypothalamus and increased VIP in the ventral tegmental area/substantia nigra. Furthermore, increased 5‐HT and 5‐HIAA tissue levels were found in the ventral tegmental area/substantia nigra. In contrast, in the frontal cortex there was a significant reduction in 5‐HIAA tissue levels and a decreased 5‐HIAA/5‐HT ratio, indicating decreased 5‐HT metabolism. Light exposure of the pigmented rat strain revealed no changes in the measured biogenic amines and neuropeptides in any investigated brain region. Our data suggest that retinal lesion but not direct visual neurotransmission induced changes in neurotransmitters in some brain regions. We conclude that Brown Norway rats but not Sprague‐Dawley rats are useful to study neurochemical effects of bright artificial light. However, Sprague‐Dawley rats may be a useful tool to study biochemical mechanisms of photoreceptor damage by bright light. © 1992 Wiley‐Liss, Inc.