bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell death, gliosis, and synaptic remodeling in the hippocampus of epileptic rats
Authors: Represa Alfonso , Niquet Jérôme , Pollard Hélène , Ben‐Ari Yehezkel 
Published: January 2005

AbstractSeizures set in motion complex molecular and morphological changes in vulnerable structures, such as the hippocampal complex. A number of these changes are responsible for neuronal death of CA3 and hilar cells, which involves necrotic and apoptotic mechanisms. In surviving dentate granule cells seizures induce an increased expression of tubulin subunits and microtubule‐associated proteins, suggesting that an overproduction of tubulin polymers would lead to a remodeling of mossy fibers (the axons of granule cells). In fact, these fibers sprout in the dentate gyrus to innervate granule cell dendrites, creating recurrent excitatory circuits. In contrast, terminal mossy fibers do not sprout in the CA3 field. Navigation of mossy fiber's growth cones may be facilitated by astrocytes, which would exert differential effects by producing and excreting cell adhesion and substrate molecules. In the light of the results discussed here, we suggest that in adult brain activated‐resident astrocytes (nonproliferating, tenascin‐negative, neuronal cell‐adhesion molecule‐positive astrocytes) could contribute to the process of axonal outgrowth and synaptogenesis in the dentate gyrus, while proliferating astrocytes, tenascin‐positive, could impede any axonal rearrangement in CA3. © 1995 John Wiley & Sons, Inc.
Molecular correlates between reactive and developmental plasticity in the rat hippocampus
Authors: Khrestchatisky Michel , Ferhat Lotfi , Charton Gérard , Bernard Anne , Pollard Hélène , Represa Alfonso , Ben‐Ari Yehezkel 
Published: January 2005

AbstractArea CA3 of the hippocampus is the most epileptogenic structure of the brain. Various studies have shown that kainate‐induced experimental epilepsy in rats and human cases of epilepsy are associated with sprouting of the mossy fibers of the dentate granule neurons and selective loss of pyramidal neurons, notably in the CA3‐CA4 areas of Ammon's horn. In experimental models of epilepsy, brief seizure activity initiates a cascade of molecular alterations that will contribute to changes in the expression of numerous genes, which can last several weeks. The products of some of these genes will contribute to the permanent state of enhanced synaptic efficiency, to the sprouting and formation of novel excitatory synapses, and possibly to neuronal cell loss. The expression of genes encoding transcription factors and numerous growth factors is rapidly altered following seizure episodes. Based on observations in vivo and in vitro in cultured hippocampal neurons, it is hypothesized that an interplay between transcription and growth factors, because of their pleiotropic effects on the regulation of effector genes, may be instrumental in coupling transient extracellular stimuli to irreversible cellular alterations. © 1995 John Wiley & Sons, Inc.
mRNA distribution within dendrites: Relationship to afferent innervation
Authors: Steward Oswald , Wallace Christopher S. 
Published: January 2005

AbstractThe majority of neuronal mRNAs are confined to cell bodies, but a few mRNAs are present at high levels in dendrites. Here we report an initial analysis of the relationship between afferent innervation and the distribution of mRNA within dendritic fields. In situ hybridization techniques were used to compare the subcellular distribution of dendritic mRNAs in principal neurons of the hippocampal formation in vivo. The mRNA encoding the α subunit of calcium/calmodulin dependent protein kinase II (CAMII kinase) was present at high levels throughout the layers that contain the dendrites of hippocampal pyramidal cells and dentate granule cells. In contrast, the mRNA encoding the high molecular weight microtubule‐associated protein MAP2 had a more limited distribution. In the dentate gyrus, labeling for MAP2 was present in a discrete band in the lamina containing proximal dendrites and decreased to low levels in laminae containing distal dendrites. This laminar pattern resembles the distinct terminations of the commissural/associational projection (high MAP2 labeling) and the entorhinal projection (lower MAP2 labeling) upon dendrites of granule cells. To determine if the differential distribution of dendritic mRNAs was regulated by either the presence or activity of afferents, we evaluated mRNA distribution in the dentate molecular layer following (1) removal of the entorhinal input by lesions of the entorhinal cortex or (2) prolonged delivery of potentiating stimulation to entorhinal afferents. Denervation led to modest decreases in the levels of mRNAs for both CAMII and MAP2 but did not lead to detectable alterations in mRNA distribution. Also, prolonged stimulation did not lead to detectable alterations in MAP2 or CAMII mRNA distribution, although such stimulation clearly elevated the expression of mRNA for glial fibrillary acidic protein (GFAP). © 1995 John Wiley & Sons, Inc.
A motoneuron spared from steroid‐activated developmental death by removal of descending neural inputs exhibits stable electrophysiological properties and morphology
Authors: Fahrbach Susan E. , DeLorme Andre W. , Klukas Kathleen A. , Mesce Karen A. 
Published: January 2005

AbstractNeurons die during the development of nervous systems. The death of specific, idenified motoneuros during metamorphosis of the tobacco hornworm, Manduca sexta, provides an accessible model system in which to study the regulation of postembryonic neuronal death. Hormones and descending neural inputs have been shown toinfluence the survival of abdominal motoneurons during the first few days of adult life in this insect. Motoneurons prevented from undergoing the normal process of developmental degeneration by removal of neural inputs were examined at the physiological and structural levels using several cell imaging techniques. Although these neurons lost their muscle targets and experienced the endocrine cue that normally triggers death, they showed no overt electrophysiological or morphological signs of degeneration. Thus, by appropriate intervention, the MN‐12 motoneuron can be spared from developmental neuronal death and remain as a functioning supernumerary element in the mature nervous system. © 1995 John Wiley & Sons, Inc.
Agrin mRNA variants are differentially regulated in developing chick embryo spinal cord and sensory ganglia
Authors: Ma Enbo , Morgan Rodney , Godfrey Earl W. 
Published: January 2005

AbstractAgrin is a synapse‐organizing protein synthesized and externalized by motor neurons in the spinal cord, which organizes the postsynaptic apparatus of the developing neuromuscular jucntion. Agin mRNA in the nervous system consists of several alternatively spliced variants. Splicing of agrin gene transcripts at the major site of variability results in four variants: encoding 8 (B8) or 11 (B11) amino acid inserts, both (B19), or a predominant variant (B0) without inserts. The insert‐containing variants are neuron specific and encode agrin proteins with greater synapse‐organizing activity than the B0 variant. Here, we report the localization and developmental regulation of agrin mRNA variants in chick embryo spinal cord and dorsal root ganglia. In situ hybridization using antisense oligodeoxynucleotide (ODN) probes specific for the B8 and B11 sequences shows that the neuorn‐specific variants are concentrated in ventrolateral cells of the chick embryo spinal cord, presumably motor neurons, begining at embryonic day 4 (E4). By E14, the insert‐containing mRNAs are found almost exclusively in presumptive motor neurons. These variants are also found in dorsal root ganglia and sympathetic ganglia, but not in non‐neural tissues. Analysis by polymerase chain reaction showed that the B11 and B19 mRNA variatns appeared in spinal cord at E4, whereas the B8 variant was first seen at E14. During development, B11 decreased and disappeared by E20, whereas B8 increased from E14 to E20. A similar time course was seen in dorsal root ganglia. The greatest acetylcholine receptor‐aggregating activity in the spinal cord was seen from E6 to E10, coincident with the highest proportion of B11‐containing transcripts and with the peak of synaptogenesis in limb muscles. These data provide the first evidence linking appearance of the neuron‐specific agrin mRNA variants with expression of the functional protien. The B11 and B19 variants appeared in E2 (stage 15) neural tubes cultured for 2 days with or without notochord and trunk tissues, indicating that there is no peripheral signal required to induce these agrin mRNA variants in developing motor neurons. © 1995 John Wiley & Sons, Inc.
Changes in the macrophage population of the rat superior cervical ganglion after postganglionic nerve injury
Authors: Schreiber R. C. , Shadiack A. M. , Bennett T. A. , Sedwick C. E. , Zigmond R. E. 
Published: January 2005

AbstractFollowing peripheral nerve transection, a series of biochemical changes occurs in axons and Schwann cells both at the site of lesion and distal to it. Macrophages differentiated from monocytes that invade the area in response to transection (elicited macrophages) and, perhaps, also macrophages normally present in the tissue (resident macrophages) play important roles in these changes. In addition, nerve transection produces changes in the cell bodies of axotomized neurons and their surrounding glial cells, located at some distance from the lesion. To determine whether macrophages might play a role in the changes occurring in the superior cervical ganglion (SCG) after axotomy, we examined the presence of macrophages before and after axonal damage. The monoclonal antibodies ED1, ED2, and OX6 were used, each of which recognizes a somewhat different population of macrophages. Ganglia from normal rats contained a population of resident cells that were ED2+ but very few that were ED1+. Within 2 days after the postganglionic nerves were transected, the number of ED1+ cells increased substantially, with little change in immunostaining for ED2. These data, in combination with published studies on other tissues, suggest that ED1 in the SCG is selective for elicited macrophages and ED2 for resident macrophages. OX6 immunostaining was prominent in normal ganglia but also increased significantly after axotomy, suggesting that it reflects both macrophage populations. Systemic administration of 6‐hydroxydopamine, a neurotoxin that causes the destruction of sympathetic nerve endings, also produced an increase in ED1 immunostaining. Thus, the change in ED1 immunostaining in the SCG does not require surgery, with the attendant servering of local blood vessels and connective tissue, but rather only the disconnection of sympathetic neurons from their end organs. The time course of the invasion of monocytes after axotomy indicates that this process is not required to trigger the biochemical changes occurring in the ganglion within the first 24 h. On the other hand, the existence of a resident population of macrophages raises the possibility that changes in those cells might be involved. © 1995 John Wiley & Sons, Inc.
Aromatase and 5β‐reductase activity in cultures of developing zebra finch brain: An investigation of sex and regional differences
Authors: Wade Juli , Schlinger Barney A. , Arnold Arthur P. 
Published: January 2005

AbstractEstrogen treatment of hatchling female zebra finches causes the masculine development of singing behavior and of the telencephalic brain regions involved in the control of song. However, early estrogen treatment of males also blocks masculine development of copulatory behavior, presumably controlled by diencephalic regions. In an effort to determine whether the differences in estrogen action are related to sex and regional differences in androgen metabolism (estrogen synthesis or androgen inactivation), we measured aromatase and 5β‐reductase activity in dissociated‐cell cultures made separately from the telencephalon, diencephalon, and also cerebellum of hatching zebra finches under a variety of conditions. Cultures from all three brain regions express high levels of aromatase and 5β‐reductase activity. Comparisons between telencephalic and diencephalic cultures of the activity and kinetics of aromatase suggest that the telencephalic cultures convert androgen to estrogen more efficiently than diencephalic cultures, which might be important in the differential action of estrogen in the two brain regions. However, the activity of neither aromatase nor 5β‐reductase was significantly different between the sexes in either telencephalic or diencephalic cultures. Thus, comparisons between the sexes do not support the idea that differences in posthatching aromatase or 5β‐reductase activity account for the pattern of sexual differentiation of the song and copulatory systems. © 1995 John Wiley & Sons, Inc.
Regulated expression of neurofibromin in migrating neural crest cells of avian embryos
Authors: Stocker Kate M. , Baizer Lawrence , Coston Tiffani , Sherman Larry , Ciment Gary 
Published: January 2005

AbstractNeurofibromatosis type 1 (NF1) is a common human genetic disease involving various neural crest (NC)‐derived cell types, in particular, Schwann cells and melanocytes. The gene responsible for NF1 encodes the protein neurofibromin, which contains a domain with amino acid sequence homology to the ras‐guanosine triphosphatase activating protein, suggesting that neurofibromin may play a role in intracellular signaling pathways regulating cellular proliferation or differentiation, or both. To determine whether neurofibromin plays a role in NC cell development, we used antibodies raised against human neurofibromin fusion proteins in western blot and immunocytochemical studies of early avian embryos. These antibodies specifically recognized the 235 kD chicken neurofibromin protein, which was expressed in migrating trunk and cranial NC cells of early embryos (E1.5 to E2), as well as in endothelial and smooth muscle cells of blood vessels and in a subpopulation of non‐NC‐derived cells in the dermamyotome. At slightly later stages (E3 to E5), neurofibromin immunostaining was observed in various NC derivatives, including dorsal root ganglia and peripheral nerves, as well as non‐NC‐derived cell types, including heart, skeletal muscle, and kidney. At still later stages (E7 to E9), neurofibromin immunoreactivity was found in almost all tissues in vivo. To determine whether the levels of neurofibromin changed during melanocyte and Schwann cell development, tissue culture experiments were performed. Cultured NC cells were found to express neurofibromin at early time points in culture, but the levels of immunoreactivity decreased as the cells underwent pigmentation. Schwann cells, on the other hand, continued to express neurofibromin in culture. These data suggest, therefore, that neurofibromin may play a role in the development of both NC cells and a variety of non‐NC‐derived tissues. © 1995 John Wiley & Sons, Inc.
Regulation of choline acetyltransferase/iacZ fusion gene expression in putative cholinergic neurons of drosophila melanogaster
Authors: Kitamoto Toshihiro , Ikeda Kazuo , Salvaterra Paul M. 
Published: January 2005

AbstractWe have analyzed the distribution of putative cholinergic neurons in whole‐mount preparations of adult Drosophila melanogaster. Putative cholinergic neurons were visualized by X‐gal staining of P‐element transformed flies carrying a fusion gene consisting of 5′ flanking DNA from the choline acetyltransferase (ChAT) gene and a lacZ reporter gene. We have previously demonstrated that cryostat sections of transgenic flies carrying 7.4 kb of ChAT 5′ flanking DNA show reporter gene expression in a pattern essentially similar to the known distribution of ChAT protein. Whole‐mount staining of these same flies by X‐gal should thus represent the overall distribution of ChAT‐positive neurons. Extensive staining was observed in the cephalic, thoracic, and stomodeal ganglia, primary sensory neurons in antenna, maxillary palps, labial palps, leg, wing, and male genitalia. Primary sensory neurons associated with photoreceptors and tactile receptors were not stained. We also examined the effects of partial deletions of the 7.4 kb fragment on reporter gene expression. Deletion of the 7.4 kb fragment to 1.2 kb resulted in a dramatic reduction of X‐gal staining in the peripheral nervous system (PNS). This indicates that important regulatory elements for ChAT expression in the PNS exist in the distal region of the 7.4 kb fragment. The distal parts of the 7.4 kb fragment, when fused to a basal heterologous promoter, can independently confer gene expression in subsets of putative cholinergic neurons. With these constructs, however, strong ectopic expression was also observed in several non‐neuronal tissues. © 1995 John Wiley & Sons, Inc.
Identification of the border between fibronectin type III homologous repeats 2 and 3 of the neural cell adhesion molecule L1 as a neurite outgrowth promoting and signal transducing domain
Authors: Appel Frank , Holm Jürgen , Conscience Jean‐François , von Bohlen Friedrich , Halbach  , Faissner Andreas , James Peter , Schachner Melitta 
Published: January 2005

AbstractTo determine the domains of the neural cell adhesion molecule L1 involved in neurite outgrowth, we have generated monoclonal antibodies against L1 and investigated their effects on neurite outgrowth of small cerebellar neurons in culture. When the 10 antibodies were coated as substrate, only antibody 557.B6, which recognizes an epitope represented by a synthetic peptide comprising amino acids 818 to 832 at the border between the fibronectin type III homologous repeats 2 and 3, was as efficacious as L1 in promoting neurite outgrowth, increasing intracellular levels of Ca2+, and stimulating the turnover of inositol phosphates. These findings suggest that neurite outgrowth and changes in these second messengers are correlated. Such a correlation was confirmed by the ability of Ca2+ channel antagonists and pertussis toxin to inhibit neurite outgrowth on L1 and antibody 557.B6. These observations indicate for the first time a distinct site on cell surface‐bound‐L1 as a prominent signal‐transducing domain through which the recognition events appear to be funneled to trigger neurite outgrowth, increase turnover of inositol phosphates, and elevate intracellular levels of Ca2+. © 1995 John Wiley & Sons, Inc.
Conditions for the primary culture of eye imaginal discs from Drosophila melanogaster
Authors: Li Chinglu , Meinertzhagen I. A. 
Published: January 2005

AbstractWe have established a primary culture system for Drosophila eye imaginal discs. With this system, we were able to obtain neurite outgrowth from intact eye discs, eye disc fragments, and dissociated eye imaginal disc cells. Immunoreactivity to antibody 24B10 indicates that these extending neurites are photoreceptor axons. Three culture media were tested for their ability to support the survival of and neurite extension from eye disc fragments in vitro at 23°C. These, with supplements, were: five parts of Schneider's Drosophila medium with four parts of basal Eagle's medium (“4+5”); Leibovitz's L‐15 medium (L‐15); and Shields and Sang's M3 modified medium (MM3). We obtained the best results with MM3 supplemented with 2% fetal bovine serum (FBS). Eye disc fragments survived in this medium for at least 20 days. Pigmentation in the nonphotoreceptor pigment cells in cultures from the prepupa required the presence of 20‐hydroxyecdysone (20‐HE) (1 μg/ml), whereas neurite outgrowth was seen in the absence of 20‐HE. Donor animals had to fall within a range of ages to obtain appropriate eye disc differentiation in vitro. Eye discs from 5‐h pupae (P+5) or older commenced ommachrome synthesis in vitro, in a temporal sequence close to that found in vivo, whereas the in vitro synthesis of this pigment was delayed in eye discs from younger flies. Average neurite length was not affected by age among pupae younger than P+5; but neurite outgrowth from P+24 was scarce, probably because by this time photoreceptor axons had already grown in vivo and were severed and unable to regenerate in vitro. Eye discs taken from third instar larvae or white prepupae continued their mitotic activity in vitro. Together with the advance of the morphogenetic furrow at the leading edge of retinal development, this observation is consistent with the evidence that pattern formation continues in vitro. Morphogenetic changes were manifested in cultures. Viability tests with calcein AM and ethidium bromide revealed few dead cells in living cultures. © 1995 John Wiley & Sons, Inc.
Comparison of different depletion strategies for improved resolution in proteomic analysis of human serum samples
Authors: Björhall Karin , Miliotis Tasso , Davidsson Pia 
Published: January 2005

AbstractSerum proteins may often serve as indicators of disease and is a rich source for biomarker discovery. However, the large dynamic range of proteins in serum makes the analysis very challenging because high‐abundant proteins tend to mask those of lower abundance. A prefractionation step, such as depletion of a few high‐abundant proteins before protein profiling, can assist in the discovery and detection of less abundant proteins that may prove to be informative biomarkers. In the present study, five different depletion columns were investigated considering efficiency, specificity, and reproducibility. Our research included quantitative determination of total protein, albumin, and immunoglobulin G (IgG) concentrations, one‐ and two‐dimensional gels and mass spectrometric analysis of the serum samples before and after the depletion step. Our results showed that all five depletion columns tested removed albumin and IgG with high efficiency. We found that based on reproducibility and binding specificity, the Multiple Affinity Removal Column that removed a total of six high‐abundant proteins (albumin, IgG, antitrypsin, IgA, transferring, and haptoglobin) offered the most promising depletion approach. Among the disposable (single‐use) products, the ProteoExtract™ Albumin/IgG Removal kit displayed the best results. Depleted serum from the Multiple Affinity Removal column was further evaluated by 2‐D gel electrophoresis (2‐DE) analysis, and the results indicated increased resolution and improved intensity of low‐abundant proteins in a reproducible fashion. Our study provides a comprehensive investigation of commercially available depletion columns and will be of high importance for future proteomic studies on serum samples.
Properties of covalently bonded layered‐silicate/polystyrene nanocomposites synthesized via atom transfer radical polymerization
Authors: Li Chung‐Ping , Huang Ching‐Mao , Hsieh Meng‐Ting , Wei Kung‐Hwa 
Published: January 2005

AbstractCovalently bonded layered silicated/polystyrene nanocomposites were synthesized via atom transfer radical polymerization in the presence of initiator‐modified layered silicate. The resulting nanocomposites had an intercalated and partially exfoliated structure, as confirmed by X‐ray diffraction and transmission electron microscopy. The thermal properties of the nanocomposites improved substantially over those of neat polystyrene. In particular, a maximum increase of 35.5 °C in the degradation temperature was displayed by these nanocomposites. Additionally, the surface elastic modulus and hardness of these nanocomposites were more than double those of pure polystyrene. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 534–542, 2005