bluuebunny/crossref_metadata_2025_split huggingface dataset:
cDNA coding for the tail region of the high molecular weight rabbit neurofilament protein NF‐H
Authors: Mack K. , Currie J. R. , Soifer David 
Published: January 2005

AbstractA cDNA library was prepared from rabbit brain mRNA, in the expression vector, lambda gt11. The library was screened with polyclonal antibodies raised against the neurofilament protein NF‐H, and a cloned cDNA (KMRH‐1) was selected and characterized. The fusion protein coded for by KMRH‐1 includes epitopes for two monoclonal antibodies which react with nonphosphorylated sites in the tail region of NF‐H. The selected cDNA includes 891 base pairs. It hybridizes to human genomic DNA, as well as to rabbit genomic DNA, and to a rabbit brain mRNA with a size of 4.7 kilobases (kb). The sequence of KMRH‐1 includes extensive repeating regions, including one duplicated 60‐base segment. Within the first 196 bases, one 13‐base segment is repeated 9 times. The cDNA codes for the carboxy‐terminal 184 amino acid residues of NF‐H, including a series of 9 serines, each surrounded by a similar group of amino acids: Ala.Lys.Ser.Pro.{Glu./Val.}.Lys. Comparison of the derived amino acid sequence for KMRH‐1 indicates considerable divergence from the sequence information available for rodent NF‐H (Robinson et al.: FEBS Lett 209:203‐205, 1986). This diversity in amino acid sequence may account for the failure to induce tangles of neurofilaments in animals, such as rats, following treatment with doses of aluminum which are sufficient to induce such tangles in rabbits and to bring on seizures and behavioral pathology in both species.
Identification of a human glial fibrillary acidic protein cDNA: A tool for the molecular analysis of reactive gliosis in the mammalian central nervous system
Authors: Rataboul P. , Biguet N. Faucon , Vernier P. , De Vitry F. , Boularand S. , Privat A. , Mallet J. 
Published: January 2005

AbstractTwo clones encoding human glial fibrillary acidic protein (GFAP) were isolated from a human astrocytoma cDNA library. The clones pHGFAP1 and pHGFAP2 were selected by the combined use of differential colony hybridization and hybridization‐selection technique with polyclonal anti GFAP antiserum. The longer one, pHGFAP1, encompasses 3.0 kb and includes the 1.8 kb long 3′ untranslated region specific to the human mRNA. Sequence data disclosed an extensive homology within the coding region of human and mouse GFAP cDNAs even in the end domains. Blot hybridization analysis of RNAs from human, rat and mouse brain revealed a single GFAP mRNA species of 3.1, 2.8 and 2.7 kb respectively and Southern blot experiments indicated that this mRNA is most probably transcribed from a unique gene. In situ hybridization performed with biotinylated probes on cultured mouse brain cells suggests both the sorting and the transport of GFAP mRNA throughout the cytoplasm and processes of the astrocytes. As a model of reactive gliosis secondary to degenerative disorders, 6‐hydroxydopamine (6‐OHDA) lesion of the substantia nigra in the rat was performed. GFAP mRNA increased 1.4 fold in the ipsilateral striatum on day 10 after the lesion. It then declined to the control level 4 months later contrasting with the lower and more sustained increase in preproenkephalin (PPE) mRNA. The interspecies cross‐reactivity of the HGFAP probes make them useful as a tool for the molecular analysis of reactive gliosis in various experimental models.
Identification of horizontal cells generating different spectral responses in the retina of a teleost fish (Eugerres plumieri)
Authors: Negishi K. , Salas R. , Parthe V. , Drujan B. D. 
Published: January 2005

AbstractSix different types of spectral responses were recorded from horizontal cells under mesopic conditions in perfused retina, isolated from the dark‐adapted mojarra (Eugerres plumieri). They were tentatively termed photopic Lr‐, Lg1‐, Lg2‐, Lb‐, and C‐type, and scotopic L‐type. The Lr‐, Lg‐, and Lb‐type responses showed a maximum peak at 605, 550, and 516 nm respectively, while the C‐type was composed of hyperpolarizing potentials in response to shorter wavelengths and depolarizing potentials in response to longer wavelengths (so‐called R/G‐type). The scotopic L‐type has a peak at 516 nm in the spectral response and a slow decay phase in the waveform response. Following a brief period of diffuse illumination, it was found that the Lgl‐type response is altered to the Lr‐type, while both Lg2‐ and Lb‐type responses change to the C‐type. Intracellular marking with Lucifer or Procion yellow identified the cellular origins of different response types: external (He) and medial horizontal (Hm) cells for the Lr‐type, internal horizontal (Hi) cells for the C‐type, and rod‐horizontal (Hr) cells for the scotopic L‐type. Only He cells were found to possess an axon, while dye coupling was seen between axonless Hm, Hi, or Hr cells but not between He cells. The morphology of these fluorescent dye‐marked cells was the same as that of the respective cells observed in Golgi‐stained materials.
Effects of radioligand oxidation and ascorbate‐induced lipid peroxidation on serotonin‐1 receptor assay: Use of ascorbate and ethylenediamine tetraacetic acid buffers to prevent (3H)‐5‐HT binding artifacts
Authors: May Patrick C. , Morgan D. G. , Salo D. , Goss J. R. , Finch C. E. 
Published: January 2005

AbstractThe effects of ascorbic acid and ascorbate‐induced lipd peroxidation upon (3H)‐5‐HT binding were examined in total membrane fractions prepared from mouse cortex and hippocampus. Low concentrations of ascorbic acid promoted lipid peroxidation of membranes as assessed by malondialdehyde production relative to intermediate concentrations of ascorbate. The actual concentration of ascorbate required for expression of pro‐oxidative and antioxidative properties was dependent upon assay conditions such as temperature and ionic constituents. Ascorbate‐induced lipid peroxidation was completely prevented by addition of 1 mM ethylenediamine tetraacetic acid (EDTA) and enhanced by GTP at concentrations typically used in binding assays. Marked lipid peroxidation was associated with loss of (3H)‐5‐HT binding sites with little effects upon affinity of the receptor for the ligand. In contrast, mild lipid peroxidation occurring during the binding assay with the ligand present was associated with a decreased affinity for (3H)‐5‐HT and the appearance of a curvilinear Scatchard plot. Under assay conditions that prevented ascorbateinduced lipid peroxidation, Scatchard analysis indicated only a single high‐affinity binding site for (3H)‐5‐HT even when assayed with an expanded range of ligand concentrations. Preparation of ligand and assay of (3H)‐5‐HT binding in the absence of ascorbate resulted in shallow, markedly curvilinear Scatchard plots. These data support the continued use of ascorbate in (3H)‐5‐HT binding assays to prevent ligand degradation and the addition of 1 mM EDTA to prevent lipid peroxidation from occurring during the binding assay.
Localization of choline acetyltransferase in perikarya and dendrites within the nuclei of the solitary tracts
Authors: Armstrong David M. , Rotler A. , Hersh L. B. , Pickel V. M. 
Published: January 2005

AbstractImmunocytochemistry was used to establish the cellular localization of choline acetyltransferase [ChAT] throughout the rostrocaudal portions of the nuclei of the solitary tracts [NTS] in rat brain. By light microscopy, two distinct populations of ChAT‐positive cells were identified. The first consisted of relatively few, medium‐sized neurons located in the caudal one‐half of the medial NTS just dorsal to the dorsal motor nucleus of the vagus. The second population of ChAT‐labeled neurons was located more anteriorly and surrounded the medial and dorsal borders of the tractus solitarius. These cells were more abundant and smaller diameter than those located more caudally. Thick, non‐varicose processes with the light microscopic characteristics of dendrites also were selectively labeled for ChAT. A few of these processes were located near or were continuous with the labeled perikarya of the NTS. However, the vast majority of the immunoreactive processes could be traced from ChAT‐labeled perikarya in the ventrally adjacent dorsal motor nucleus of the vagus. These dorsally directed dendrites aborized extensively throughout the NTS, but they were densest in the rostral two‐thirds of the nucleus. Caudally, the labeled dendrites coursed horizontally, forming a commissure‐like structure between the two vagal motor nuclei.Electron microscopy confirmed the perikaryal and dendritic localization of ChAT in the NTS. The perikarya were characterized by dense peroxidase immunoreactivity throughout the cytoplasm, infolded nuclear membranes, and somatic synapses. The labeled dendritic profiles also were intensely immunoreactive and received synaptic input from unlabeled terminals. The unlabeled afferents to somata and dendrites contained large populations of small clear vesicles. The abundance of cholinergic dendrites and relative sparsity or absence of identified cholinergic axons suggests that the release of acetylcholine from dendrites of intrinsic neurons or from dendrites of neurons located within the dorsal motor nucleus of the vagus may be important for cholinergic modulation of visceral functions within the NTS.
Fibroblast growth factor effects on peripheral nerve regeneration in a silicone chamber model
Authors: Danielsen N. , Pettmann B. , Vahlsing H. L. , Manthorpe M. , Varon Silvio 
Published: January 2005

AbstractWe have developed a silicone nerve regeneration chamber that is partitioned into two compartments by a strip of nitrocellulose paper. The modified two‐compartment chamber allows the investigation of the effects on rat sciatic nerve regeneration of trophic or growth factors that are initially bound to the nitrocellulose partition. In this study we compared the effects of untreated nitrocellulose, a siliconized nitrocellulose strip, and a strip that had been soaked in a basic fibroblast growth factor (FGF) solution. FGF is a known angiogenic factor and a mitogen for endothelial cells, fibroblasts, and Schwann cells. All of these cell types are present in the peripheral nerve. In vitro analyses, using 3T3 cells as test cells, showed that some of the bound FGF remained active on the nitrocellulose paper for at least 8–10 days. In vivo experiments, examined at 16 days post‐implantation, revealed that spatial migration of all cellular elements (perineurial‐like cells, vasculature, and Schwann cells) across the chamber gap was slower with untreated nitrocellulose strips than with siliconized strips but was most advanced with FGF‐treated ones. Most striking was the well‐developed vascular arborization of the regenerate within the FGF chambers. Histologic sections from the proximal one‐half of the chamber revealed that the regenerate in untreated strip chambers consisted of fibrin matrix and erythrocytes, whereas a welldeveloped structure with all the cellular elements of a regenerating nerve was seen in several of the FGF strip chambers. We conclude that FGF stimulates peripheral nerve regeneration in this model.
Glutamate decarboxylase inhibition and vitamin B6 metabolism in brain of cirrhotic rats chronically treated with carbon tetrachloride
Authors: Díaaz‐Muñtoz M. , Tapia Ricardo 
Published: January 2005

AbstractIn a previous work we found that the activity of glutamate decarboxylase (GAD), the enzyme responsible for the synthesis of the inhibitory neurotransmitter γ‐aminobutyric acid (GABA), is decreased in comatose cirrhotic rats after chronic treatment with CCl4. In the present report we studied the participation of pyridoxal phosphate in the inhibition of GAD, as well as the concentration of this coenzyme and the activity of its synthesizing enzyme, pyridoxal kinase, in the brain of the cirrhotic rats. Furthermore, cirrhotic animals were treated with three inhibitors of GAD, and the effects of such treatment were compared to those of ammonium. Liver failure resulted in a 25% inhibition of GAD activity when measured in the absence of added pyridoxal phosphate. Treatment with the GAD inhibitors thiosemicarbazide or 3‐mercaptopropionic acid enhanced this inhibition and produced convulsions at a dose that had no behavioral effects in control rats. Treatment with ammonia resulted in a comatose state and in a 25–40% inhibition of GAD. Both pyridoxal kinase activity and pyridoxal phosphate levels were found to be decreased by 15–20% in the brain of the cirrhotic rats. We concluded that chronic liver failure results in a decreased pyridoxal phosphate and GABA synthesis in brain, with a consequent diminished efficiency of GA‐BAergic neurotransmission; these effects are probably related to the manifestations of neuronal hyperexcitability that are frequently seen in human hepatic encephalopathy.
Embryonic exposure to high taurine: A possible nutritional contribution to Friedreich's ataxia
Authors: van Gelder N. M. , Bélanger F. 
Published: January 2005

AbstractWhen fertilized eggs (50 g) are injected on day 1 with 100 μmol taurine (0.2 ml), 15‐day‐old embryos exhibit increased taurine content in heart and brain. Lethal toxicity was no higher than with equimolar injections of NaCl (50 μmol) or valine (100 μmol) of the same volume. That same dose of taurine injected either on embryonic day 1 or 7 produced in hatchlings a typical syndrome of ataxia, reduced muscle strength and motor incoordination. When injected on embryo day 15 (E15) most chicks appeared incapable of pecking out of the egg, and the resulting delay in hatching, if if did occur, precluded presuming that the poor condition of such chicks was exclusively due to the late taurine injections.In view of the tendency of Friedreich's ataxia patients to exhibit increased alimentary absorption of taurine, and to demonstrate an excessive accumulation of taurine in the cerebellum and heart tissue on autopsy, fetal exposure to high taurine levels or neonatal high taurine milk ingestion may, by analogy, contribute to the slowly progressing disease process.
Protein synthesis by rat hippocampal slices maintained in vitro
Authors: Phillips L. L. , Steward O. 
Published: January 2005

AbstractThe present study evaluates protein synthesis in rat hippocampal slices maintained in vitro. Transverse slices of hippocampus were prepared from both adult rats and rat pups during postnatal development and incubated in a gassed (95% O2/5% CO2) balanced salt medium containing 5 nM 3H‐leucine. The time course of 3H‐leucine incorporation into TCA‐precipitable protein was determined using slices removed from the media after 5, 10, 20, 30, 40, 60, and 120 min of incubation. The pattern of 3H‐amino acid incorporation was evaluated by fixing slices with paraformaldehyde, embedding the slices in plastic, and sectioning the slices end on and en face for autoradiographic analysis.Biochemical analysis of 300 and 400 μm slices revealed that incorporation of leucine into protein proceeds at a constant rate. The autoradiographic analysis revealed that in adult hippocampal slices of 300–600 μm thickness there was complete penetration of 3H‐leucine with no indication of a gradient in the extent of incorporation throughout the slice. The pattern of grain density within 300–600 μm slices matches that previously reported after in vivo injections of radio‐labeled amino acid, where grain density is highest over neuronal cell bodies and lower over the laminae that contain dendritic processes and axons (Phillips et al: Mol Brain Res 2:251–261, 1987). Hippocampal slices of 200, 800, and 1,000 μm thickness showed irregular labeling. Slices of 200 μm were filled with pyknotic nuclei and vacuoles and exhibited patchy labeling. In 800 μm slices there were isolated areas of good preservation within the slice core, but these areas exhibited little incorporation. Relative to the 300–600 μm slices, there was a higher number of pyknotic nuclei and a much deeper layer of necrosis along the cut edges. Slices of 1,000 μm thickness showed poor preservation throughout and low levels of incorporation. Biochemical studies revealed a much higher rate of incorporation in the slices prepared from postnatal animals. Autoradiography of the slices from developing rats revealed that penetration was excellent and incorporation appeared to be greater as judged by an overall higher grain density.We believe that rat hippocampal slices provide a good in vitro model of protein metabolism that will be useful for studies of protein synthesis in isolated cell body and dendritic laminae and for the evaluation of whether protein synthesis in particular laminae is regulated by synaptic activity.
Migration‐related changes in the cytoskeleton of cultured neural crest cells visualized by the monoclonal antibody I‐5G9
Authors: Wright J. , Cooley B. , Duwell J. , Sieber‐Blum M. 
Published: January 2005

AbstractAn epitope recognized by the monoclonal antibody I‐5G9 was expressed by all neural crest cells shortly after explantation into culture. At this time all neural crest cells actively migrated away from the neural tube. Immunoreactivity was localized intracellularly and organized into stress fiber‐like filaments. Often, immunofluorescence was particularly high in short fibers in the lamellipodia of the reading edge of migrating cells. Two‐week‐old cultures had a diameter of 8–10 mm. At that stage a ring of immunoreactive cells was present at the periphery of each culture, an area where cells were still migratory. An inner concentric circle had reduced and more granular staining. In this area cells had ceased to migrate. In the center of the culture cells were multilayered, nonmigratory, and did not bind I‐5G9. After creating a lesion in the nonreactive central region, some cells resumed migration into the lesioned area and reexpressed the epitope. I‐5G9 staining and phalloidin fluorescence colocalized partially in some cells and completely in others. It is concluded that the epitope recognized by I‐5G9 is expressed in a migration‐dependent manner. The partial colocalization of I‐5G9 and phalloidin fluorescence supports the notion that the epitope recognized by I‐5G9 is specifically expressed in stress fibers of migratory cells, possibly in one of the actin‐associated proteins or an F actin‐associated protein complex.
Insulin‐like growth factor I promotes cell proliferation and oligodendroglial commitment in rat glial progenitor cells developing in vitro
Authors: McMorris F. A. , Dubois‐Dalcq M. 
Published: January 2005

AbstractWe investigated the mechanisms by which insulin‐like growth factor I (IGF‐I) acts to increase the number of oligodendrocytes that develop in cultures of cells explanted from perinatal rat cerebrum. Fluorescence‐activated cell sorting was used to isolate bipotential A2B5‐positive oligodendrocyte‐type 2 astrocyte (O‐2A) progenitor cells, which were then inoculated as single cells into microculture wells containing feeder layers of X‐irradiated type 1 astrocytes. Addition of 100 ng/ml IGF‐I to the culture medium increased the growth rate and the ultimate size reached by the resulting clones during the 18‐day experimental period. Moreover, 75–80% of the cells in the IGF‐I‐treated clones differentiated into galactocerebroside (GC)‐positive oligodendrocytes, whereas only 25–30% became oligodendrocytes in the absence of IGF‐I. IGF‐I did not increase the number of type 2 astrocytes that developed in the clones. IGF‐I appeared to have the greatest effect on growth and differentiation at a stage when the majority of the cells in the clones were at an intermediate stage of development, characterized by the expression of A2B5 and O4 glycolipid antigens but not GC. Analysis of the effects of IGF‐I on O4‐positive, GC‐negative intermediate precursor cells revealed a two to fivefold increase in the number of cells that incorporated 3H‐thymidine into their DNA during a 5‐h pulse. Moreover, IGF‐I increased the number of cell sorter‐purified O4‐positive cells that developed into oligodendrocytes 4–8 days later. Therefore, IGF‐I acts in two different ways to promote oligodendrocyte development: It promotes proliferation of precursor cells in the O‐2A lineage, and it induces precursors to become committed to develop into oligodendrocytes.
Expression and phosphorylation of the mid‐sized neurofilament protein NF‐M during chick spinal cord neurogenesis
Authors: Bennett G. S. , Hollander B. A. , Laskowska D. 
Published: January 2005

AbstractThe middle molecular weight polypeptide of neurofilaments (NF‐M) is modified posttranslationally by extensive phosphorylation. This modification is slow in mature neurons, requiring approximately 24–48 hr for completion and probably occurs outside of the cell soma (Bennett and DiLullo: J Cell Biol 100:1799, 1985c). Thus, NF‐M synthesis and phosphorylation are separate events both temporally and spatially. Although it is known that NF‐M is among the earliest neuron‐specific gene products to be expressed during nervous system development, it is not known what the temporal relationship is between the initiation of NF‐M translation and its phosphorylation. To address this question, we have produced an antiserum against the dephosphorylated form of NF‐M (NF‐M130) and have used this antiserum, together with a previously characterized antiserum against completely phosphorylated NF‐M (NF‐M160), in an immunohistochemical examination of neurogenesis and the initial period of neuronal differentiation in chick spinal cord. We found that (1) nonphosphorylated and partially phosphorylated NF‐M cannot be detected prior to the completion of the terminal mitosis; (2) most postmitotic neuroblasts begin expressing NF‐M as they commence migration, but do not contain the completely phosphorylated polypeptide until some time after completion of migration; and (3) those precursor cells of a subpopulation of neuroblasts that begin expressing completely phosphorylated NF‐M during their terminal cell cycle (Bennett and DiLullo: Dev Biol 107:94, 1985a) contain no detectable nonphosphorylated or partially phosphorylated NF‐M. These cells probably complete the phosphorylation step more rapidly than do mature neurons.
Tissue plasminogen activator binding to mouse cerebellar granule neurons
Authors: Verrall S. , Seeds N. W. 
Published: January 2005

AbstractCultures of dissociated neonatal mouse cerebellar cells secrete primarily tissue plasminogen activator (tPA) and to a lesser extent urokinase plasminogen activator (uPA) into the culture medium. Fibrin overlays have localized plasminogen activator to granule neurons in these cultures; furthermore, this granule cell plasminogen activator activity is blocked by an antibody to tPA. Developmental studies indicate that maximal levels of soluble plasminogen activator in the culture medium preceed the peak of fibrinolytic activity by these cultures, suggesting that secreted PA may bind back to the surface of these granule neurons. Here we show that granule cell‐associated tPA can be displaced by a brief pH shock. However, incubation of these fibrinolytically inactive cultures with exogenously added mouse tPA leads to a specific binding of active tPA to granule neurons as visualized by subsequent fibrin overlay. In similar studies mouse uPA, human uPa, and human tPA fail to show fibrinolytic activity associated with the cerebellar culture, whereas mouse tPA fails to bind to cerebellar glial cell cultures. These findings suggest that granule neurons possess binding sites for tPA on their surface, where this protease can retain its functional activity and may play an important role in cell migration or other cell activities.