bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential neuronal expression of c‐fos proto‐oncogene following peripheral nerve injury or chemically‐induced seizure
Authors: Jones K. J. , Evinger C. 
Published: January 2005

AbstractPrevious work by others has demonstrated that neocortical injury results in the induction of c‐fos proto‐oncogene both at and distal to the site of injury. However, secondary effects of focal brain injury, such as spreading depression and seizure activity, also have been shown to induce the expression of c‐fos. Thus, it is unclear whether the stimulus inducing c‐fos expression after generalized brain trauma is direct neuronal injury or associated, secondary effects of injury. In this study, we tested the hypothesis that a specific axonal disconnection would induce the expression of c‐fos proto‐oncogene in the injured neurons. The injury paradigm that was used was peripheral axotomy of rodent facial motoneurons. The right facial nerve was severed distal to the stylomastoid foramen, with the left side serving as an internal control. As positive controls, in a separate group of animals, seizures were invoked using bicucullin administered intraperitoneally. At the end of postoperative survival times ranging from 30 min to 24 hr, the animals were sacrificed. For northern blot analysis using a c‐fos cDNA probe, total RNA was isolated from the dissected facial nuclear groups in the injury experiments, or whole brain and neocortex in the seizure experiments. For immunocytochemical analysis using a battery of c‐fos antibodies, the animals were perfused with paraformaldehyde and processed for routine light microscope immunocytochemistry. In the bicucullin‐injected animals, c‐fos mRNA was massively induced in whole brain in a manner proportional to the overall level of gross seizure activity. The localization of the c‐fos expression occurred primarily in neurons within the neocortex. In the axotomized facial motoneurons, no induction of c‐fos mRNA or protein was found to occur at any of the timepoints examined and no basal expression of c‐fos was observed in the uninjured motoneurons. The results suggest that the rapid induction of c‐fos proto‐oncogene product is not a specific component of the nerve cell body response to injury.
Influence of innervation on molecular forms of acetylcholinesterase in regenerating fast and slow skeletal muscles
Authors: Črne N. , Sketelj J. , Brzin M. 
Published: January 2005

AbstractNerve‐intact muscle regenerates were prepared by ischemic‐toxic injury of slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of the rat. Rapid innervation of regenerating myotubes modified intrinsic patterns of AChE molecular forms, revealed by velocity sedimentation in linear sucrose gradients. Regarding their onset, the effects of innervation can be classified as early and late. The earliest changes in the SOL regenerates appeared a few clays after inner vation by their motoneurons: The activity of the 13 S AChE form (A 8) increased significantly in compari son to non‐innervated regenerates. The pattern of AChE molecular forms became similar to that in the normal SOL muscle during the 2nd week after in jury. In contrast, no major differences were observed between 8 day‐old innervated and non‐innervated EDL regenerates. Their patterns of AChE molecular forms resembled that in the normal EDL. However, the predominance of the 10 S AChE form (G 4) char acteristic for the 2‐week old non‐innervated regener ates was prevented by innervation. Early effect of innervation observed in the SOL regenerates but not in the EDL may be due to intrinsically different re sponse of the regenerating SOL myotubes to innerva tion. Rather high extrajunctional activity of the asymmetric 16 S (A 12) molecular form of AChE in early regenerates was reduced to adult level in about 3 weeks in the SOL, and nearly completely sup pressed in 5 weeks after innervation in the EDL re generates. This reduction is assumed to be a late ef fect of innervation, as well as a decrease of the activity of the 4 S AChE form (G 1) in the SOL regenerates. A suppressive mechanism is activated in the extra junctional regions of the innervated muscle regener ates during their maturation. This mechanism coun teracts the enhancing influence of contractile activity on the expression of the asymmetric AChE forms in immature muscle cells, and is more efficient in the EDL than in the SOL. Its onset may be apparently delayed by protracted fusion of the satellite cells with muscle fibers.
Analysis of a decreased Na+ conductance by tumor necrosis factor in identified neurons of Aplysia kurodai
Authors: Sawada M. , Hara N. , Maeno T. 
Published: January 2005

AbstractThe ionic mechanism of the effect of extracellularly ejected recombinant human tumor necrosis factor‐alpha (rhTNF‐α) on the membrane of identified neurons R9 and R10 of Aplysia kurodai was investigatedwith conventional voltage‐clamp, micropressure ejection, and ion substitution techniques. Micropressureejected rhTNF caused a marked hyperpolarization in the undamped neuron. Clamping the same neuron at its resting potential level (–60 mV) and reejecting rhTNF‐α with the same doseproduced a slow outward current [Io(TNF)] associated with a decrease in input membrane conductance. Io(TNF) was decreased by depolarization and increased by hyperpolarization. The extrapolated reversal potential of Io}(TNF) was approximately +10 mV. Ion substitution and pharmacological experiments suggest that I}o(TNF) in identified neurons R9 and R10 of A. kurodai is due to a decreased Na+ conductance but not due to an activation of the Na+ ‐K+ Pump. Our results demonstrate that the immunomodulator TNF can act directly on the nervous system as well as on the immune system.
Age‐dependent decrease of process formation by cultured oligodendrocytes is augmented by protein kinase C stimulation
Authors: Yong Voon Wee , Cheung J. C. B. , Uhm J. H. , Kim S. U. 
Published: January 2005

AbstractThe proportion of cultured rat oligodendrocytes (OL) that extended processes of over three soma diameter in length is dependent on the age of the animals from which the brains were derived; up to 70% of neonatal OL attained this criterion within 3 days, and this proportion progressively decreased with advancing ages of the animals (1, 3, and 6 months). The lower extent of process formation from older rat OL could he augmented, and indeed to equal neonatal levels, by treatment of cells with phorbol esters that stimulate protein kinase C: 4β‐phorbol‐12,13‐dibutyrate (PDB) and phorbol‐12‐myristate‐13‐acetate (PMA). Enhancement of process formation, by PDB and PMA was also observed for cultured adult human and bovine OL. For adult OL from all three species, a phorbol ester that binds but that does not activate protein kinase C, 4α‐phorbol‐12,13‐didecanoate, did not result in enhancement of process formation. Selectively to biologically active phorbol esters was shown by the inability of a wide range of growth factors to promote process extension. Immunohistochemical analyses indicate that the type III isozyme of protein kinase C predominates in cultured OL; the apparent intensity of immunoreactive PKC was not different between controls or cultures treated for 12 days with PDB, suggesting that the persistent presence of PDB might not have down‐regulated the enzyme, in contrast to other cell types. We propose that stimulation of protein kinase C is critical to the triggering of process formation by cultured OL in vitro.
Quantitation of the growth‐associated protein B‐50/GAP‐43 and neurite outgrowth in PC12 cells
Authors: San E. R. A. Jap Tjoen , Schmidt‐Michels M. H. , Spruijt B. M. , Oestreicher A. B. , Schotman P. , Gispen W. H. 
Published: January 2005

AbstractA combined assay to measure neurite outgrowth and B‐50/GAP‐43 levels in PC 12 cells is reported. During NGF‐induced neuritogenesis, B‐50/GAP‐43 expression was monitored by enzyme‐linked immunosorbent assay (ELISA). Neurite outgrowth was quantified at the same time by the use of video image analysis. Sensitivity and reliability of the methods are shown with a dose–response and time curve of β‐NGF‐induced neuritogenesis. A linear increase in total length of neurites was induced by concentrations of β‐NGF ≥5 ng/ml and was accompanied by a linear increase in the amount of B‐50/GAP‐43. The combined methods presented here can conveniently and reliably establish subtle changes in neurite outgrowth and intracellular protein contents.
Olfactory Schwann cells are derived from precursor cells in the olfactory epithelium
Authors: Chuah M. I. , Au C. 
Published: January 2005

AbstractIn this morphological and immunohistochemical study we show that olfactory schwann cells (OSC) are derived from precursor cells residing in the olfactory epithelium. During development, they migrate out of the epithelium and extend processes to ensheath the olfactory axons.Olfactory mucosa from E14 rat embryos and juvenile rats were treated with trypsin‐pancreatin to remove the underlying connective tissue. The epithelial explant was then maintained for two days in culture, during which cells migrated out from the explant. Among them were spindly bipolar cells which were identified as OSC by their positive immunoreaction for glial fibrillary acidic protein, ultrastructure, and association with growing axons. Axonal growth was significantly more profuse in the embryonic explants, in which the polarity of the OSC was oriented parallel with the axons. Ultrastructural observations showed that ensheathment of the bundles of axons resembled those in vivo.
Oligodendrocytes of the jimpy phenotype can be partially restored by environmental factors in vivo
Authors: Lachapelle F. , Lapie P. , Campagnoni A. T. , Gumpel M. 
Published: January 2005

AbstractCross‐transplantations of neural tissue between jimpy (jp) shiverer (shi) and normal mice have been performed under heterochronic conditions. In all series, fragments of E14–E15 embryonic neural tissue from the different donors have been transplanted into newborn host brain in order to study environmental influences by differentiated tissue on transplanted embryonic cell lines. Large patches of proteolipid protein (PLP)‐positive myelin have been observed in the jp brain after transplantation of shi or normal embryonic tissue into the newborn jp brain, suggesting that the jp parenchyma did not inhibit the differentiation of other Oligodendrocytes (ODCs). Jp embryonic tissue had the same mitotic potential as normal tissue, as demonstrated by the larger size of myelin patches observed when jp embryonic tissue was used instead of newborn jp tissue. By contrast, whatever the conditions, jp myelin patches were always obviously smaller than normal or shi myelin patches, suggesting that the myelinating capacity of jp ODCs was not enhanced by environmental factors. Finally, comparison of the ratie of successful outcomes observed following embryonic vs. newborn jp donor tissue, strongly suggests a partial or total normalization of jp embryonic ODCs survival by a more mature shi environment.
Adhesion and proliferation are enhanced in vitro in Schwann cells from nerve undergoing wallerian degeneration
Authors: Komiyama A. , Novicki D. L. , Suzuki Kinuko 
Published: January 2005

AbstractProliferation of Schwann cells during nerve degeneration or regeneration is well documented in vivo. We investigated whether the proliferative response of Schwann cells to injury is retained in vitro. Using 5‐month‐old male C57BL mice, Schwann cells were isolated from sciatic nerves under 3 experimental conditions: (1) uninjured, (2) after permanent nerve‐transection, or (3) after nerve‐crush, which permits axonal regeneration. Schwann cells rarely attached to polylysine‐coated coverslips when isolated from uninjured or 1 day posttransection/crush nerves. The number of adherent cells increased when Schwann cells were isolated 3 days after nerve‐transection or‐crush. When cells were isolated from transected nerves, cell adhesion reached a peak 2 weeks after the injury and then declined. Maximal attachment of Schwann cells occurred when the cells were isolated 2–4 weeks after nerve‐crush. The percentage of Schwann cells with spreading processes corresponded closely with the number of thymidine‐labeled cells at 1 day in vitro. The in vitro capacity of cells to spread and incorporate thymidine reached maximal levels at 5 days posttransection/crush. Capacity of cells to spread and incorporate thymidine subsequently decreased with time following transection. However, a biphasic elevation in cell spreading and thymidine incorporation was observed in Schwann cells isolated from crushed nerves. Maximal growth of Schwann cells in vitro occurred at 1–2 weeks posttransection and at 1–4 weeks postcrush. Adhesion and spreading of Schwann cells were promoted by coating coverslips with laminin or fibronectin. Preincubation of Schwann cells with soluble laminin or fibronectin prevented the initial cell attachment induced by the corresponding protein. Our results suggest that Schwann cells from injured nerves possess binding sites for laminin and fibronectin, which are, in part, responsible for the enhanced adhesion of Schwann cells in vitro. This study provides a new method for preparation of Schwann cells from peripheral nerves of adult mice.
Autoradiographic study of iron‐binding sites in the rat brain: Distribution and relationship to aging
Authors: Barkai A. I. , Durkin M. , Dwork A. J. , Nelson H. D. 
Published: January 2005

AbstractSpecific binding of 59Fe to various brain structures was investigated in rats using nanomolar concentrations of 59FeCl3 and quantitative aiitoradiography. Saturation studies revealed high affinity binding (kd in the nanomolar range) with binding sites density (Bmax) which varied in different brain regions from 462 fmol per mg tissue in the central thalamic nuclei to over 4 pmol per mg tissue in the cerebral peduncle. Binding was seen in both white and gray matter structures. Bmax values for frontal cortex, dentate gy‐rus, and substantia nigra were significantly lower in older rats. The distribution of 59Fe binding sites was not consistent with the distribution of brain iron as reported by other investigators. 59Fe binding was reduced significantly in the presence of free radicals. These observations suggest that high affinity binding sites for iron are localized differentially in various brain structures and may play an important role in the translocation and storage of potentially harmful ferric cations in brain. The finding that the capacity of the brain tissue to bind iron diminished with age in discrete brain regions suggests that in the aged animal, the removal of “free” iron from the cellular domain may be impaired in such regions, leading to increased susceptibility to iron‐enhanced lipid peroxidation and cell death.
Peripheral nerve regeneration is impeded by interleukin‐1 receptor antagonist released from a polymeric guidance channel
Authors: Guénard V. , Dinarello C. A. , Weston P. J. , Aebischer P. 
Published: January 2005

AbstractInterleukin‐1 receptor antagonist (IL‐lra), a true antagonist of the interleukin‐1 (IL‐1) receptors, is released by activated macrophages and binds specifically to the IL‐1 receptors without triggering IL‐1 effects. Following peripheral nerve axotomy, activated macrophages release IL‐1, which induces the expression of nerve growth factor (NGF) mRNA in Schwann cells. IL‐lra may therefore impede peripheral nerve regeneration by blocking the NGF‐mediated effect of IL‐1. Peripheral nerve regeneration occurring through polymeric guidance channels releasing IL‐lra was investigated in a 4‐mm gap transected mouse sciatic nerve model. Cohorts of five animals were implanted with tubes releasing either bovine serum albumin (BSA), BSA with IL‐lra, or BSA with deactivated IL‐lra (dlL‐lra) for 4 weeks. In vitro release kinetics indicated that after an initial burst, IL‐lra release was linear for the next 3½ weeks. Following implantation of a polymeric guidance channel, a regenerated cable bridged the nerve gap in all animals. The cables were similar in size and were composed of nerve microfascicles containing both unmyelinated and myelinated axons in association with their Schwann cells. Tissue regenerated in tubes releasing BSA‐IL‐lra contained, however, significantly fewer myelinated and unmyelinated axons and blood vessels than did tubes releasing BSA alone or BSA‐dIL‐lra. We conclude that a naturally occurring antagonist of IL‐1 receptors impedes peripheral nerve regeneration, suggesting that macrophages play an essential role in controlling peripheral nerve regeneration through the release of stimulatory and/ or inhibitory molecules.
Protein kinase C stimulation enhances the process formation of adult oligodendrocytes and induces proliferation
Authors: Althaus H. H. , Schröter J. , Spoerri P. , Schwartz P. , Klöppner S. , Rohmann A. , Neuhoff V. 
Published: January 2005

AbstractOligodendrocytes (OL) isolated from adult pig brains regenerate their processes and form a network of fibers after 14–18 days in vitro (DIV). Stimulation of protein kinase C (Pk‐C) by tumour promoters such as 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) produces at day 7 in vitro a similar network after only 20 hr. H‐7, an inhibitor of Pk‐C, as well as amiloride, which inhibits the subsequent Na+/H+ exchange, reversibly suppress this effect. Activation of the protein kinase A or calmodulin pathway do not result in an increased OL process production. Furthermore, TPA induced proliferation in a subpopulation of OL. We conclude that the stimulation of Pk‐C is of utmost importance for OL regeneration.
Analysis of neurotransmitter receptors mediating changes in LH release induced by electrical stimulation of the dorsal raphe nucleus in the rat
Authors: Johnson J. H. , Kitts C. S. 
Published: January 2005

AbstractWe report studies of neurotransmitter and receptor species mediating the inhibition of LH release in ovariectomized (OVX) rats and stimulation in OVX estrogen‐primed rats induced by electrical stimulation of the dorsal raphe nucleus (DRN). Attempts were made to block effects of stimulation of the DRN in groups of four to nine ovariectomized rats with or without priming with estradiol benzoate (EB) by pre‐treatment with the 5HT receptor antagonists ke‐tanserin, methysergide, or metergoline; the α‐adrenergic antagonist phenoxybenzamine; or the opiate antagonist naltrexone. Blood samples were collected via jugular cannulae from the unanesthetized rats at 10‐min intervals before and during electrical stimulation of the DRN, and assayed by double antibody radioimmunoassay for LH. To test the effect of stimulation, data from animals in each treatment group were subjected to analysis of variance to obtain the contrast matrix including prestimulation and stimulation time points of interest. The contrast matrix was then used to construct an F ratio and thereby to evaluate the level of significance. In unprimed OVX rats the sustained decrease in plasma LH concentration during stimulation was prevented in rats pretreated with ketanserin or phenoxybenzamine. Methysergide pretreatment delayed the inhibitory effect of DRN electrical stimulation for 30 min, whereas metergoline and naltrexone were ineffective. In EB‐primed animals the increase in plasma LH observed during stimulation was prevented in rats pretreated with metergoline, and reversed in those receiving naltrexone. Ketanserin limited the duration of the increase to 10 min, while phenoxybenzamine and methysergide had no significant effect. These results suggest that the inhibitory effect of dorsal raphe stimulation on release of LH in OVX rats may be mediated by 5HT2 and α‐adrenergic systems, whereas the stimulatory effects (OVX + EB) may involve primarily 5HT1 and opiate receptors.
Taurine‐deficient cultured cerebellar astrocytes and granule neurons obtained by treatment with guanidinoethane sulfonate
Authors: Morán J. , Pasantes‐Morales H. 
Published: January 2005

AbstractMouse cerebellar granule neurons and astrocytes grown in the presence of 2 mM guanidinoethane sul‐fonate (GES) exhibited a progressive and rapid decrease in taurine concentration. A reduction of 20% was observed as early as 1 hr after exposure to GES and the loss of cell taurine continued until the taurine pool was reduced by about 90%. This remaining taurine persisted without further decrease even after 3 weeks of exposure to GES. Taurine reduction caused by GES was similar in both types of cells. The effect of GES was dose‐dependent, with significant decreases in taurine levels already detected at 100 μM. It was selective for taurine, since none of the other free amino acids were affected. Taurine depletion induced by GES was totally reversible. Intracellular taurine was not mobilized by GES. Taurine uptake in both astrocytes and granule neurons, examined at the taurine concentration present in the culture medium, was practically abolished by 2 mM GES. This approach represents an in vitro model of taurine depletion that may be useful to investigate the cell abnormalities responsible for the failure of differentiation and migration of granule cells and astrocytes observed in taurine‐deficient cats.
Inhibition of GFAP synthesis by antisense RNA in astrocytes
Authors: Yu A. C. H. , Lee Y. L. , Eng L. F. 
Published: January 2005

AbstractGlial fibrillary acidic protein (GFAP) accumulation is a prominent feature of astrocytic gliosis. The inhibition or delay in GFAP synthesis might delay scar formation resulting from an insult such as spinal cord injury or central nervous system (CNS) demyelination. The delay in the formation of a physical barrier might allow the neurons and oligodendrocytes to reestablish a functional environment. We delivered antisense GFAP RNA complexed with LipofectinTM (LF), a cationic liposome, into cerebral astrocytes in culture and tested the feasibility of inhibiting GFAP synthesis. Our results demonstrate that LF facilitated antisense RNA uptake into astrocytes. Astrocytes took up 3H‐antisense GFAP RNA alone and reached an equilibrium of 7–8.8 ηg per mg protein after 2.5 hr. When complexed with LF, astrocytes could increase the uptake to 14 ηg per mg protein and the time for reaching this quantity was shortened to 10 min. This uptake level was further enhanced if experiments were carried out in HEPES buffered saline (HBS). All uptake studies were dose‐ and time‐dependent. Dibutyryl cyclic AMP (dBcAMP) is known to induce an increase of GFAP content in cultured astrocytes. We studied the effect of LF/antisense GFAP RNA on the GFAP content in dBcAMP (0.25 mM)‐treated astrocytes. Cultures of astrocytes treated with dBcAMP contained almost twice as much GFAP as untreated cultures after 2 days. Similar cultures treated with LF/antisense RNA in HBS did not show an increase but a 30–40% decrease in GFAP content 2 days after treatment. A similar decrease in GFAP content was obtained in cultures grown in a chemically defined medium, another condition known to induce an increase in GFAP content in cultures. This study has demonstrated that antisense GFAP RNA can inhibit GFAP synthesis in astrocytes and may be useful for regulating astrogliosis immediately following CNS injury.