bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental dynamics of Purkinje cells and dendritic spines in rat cerebellar cortex
Authors: Takács J. , Hámori J. 
Published: January 2005

AbstractQuantitative morphological changes of the developing Purkinje cells were studied from 6 to 90 postnatal (PN) days in the IVth lobule of vermis in the cerebellum of rats. The soma size (mean diameter) of Purkinje cells increased rapidly between 6 PN (on average 10 μm) and 18 PN (about 17 μm) days; it did not change between 18 and 25 PN days, but increased moderately again between 25 and 48 PN days (22–23 μm) and stabilized on the same value. In contrast, the number of Purkinje cells/100 μm (the “linear density”) decreased rapidly from 6 to 18 PN days. The molecular layer area belonging to 1 Purkinje cell increased rapidly from 6 to 25 PN days (from about 370 to 6,200 μm2) and less rapidly between PN days 30 to 48 (up to 9,300 μm2), followed by a moderate decrease at PN day 90 (about 6,600 μm2). The volume belonging to 1 Purkinje cell dendritic arbor was about 5,500 μm3 at PN day 6,93,000 μm3 at PN day 25, and 100,000 μm3 at PN day 90. The numerical density of dendritic spines in the molecular layer showed a biphasic curve: a rapid increase from PN days 6 to 21 followed by a significant but short decrease at PN day 25, moderate rise from PN days 25 to 48, and a subsequent decline between PN days 48 and 90. The number of spines belonging to 1 Purkinje cell showed two developmental “peaks”: the first peak at 21 PN days was moderate (5.6 × 104 spines/Purkinje cell) while the second maximum at 48 PN days was more significant (1.2 × 105 spines/Purkinje cell), which then declined to 6.3 × 104 spines/Purkinje cell at PN day 90. It is suggested that the temporary overproduction and the following decline in the number of Purkinje dendritic spines during the development of the cerebellar cortex may be the morphological indicator of the dynamics of synaptogenetic and of synaptic stabilization processes. © 1994 Wiley‐Liss, Inc.
Neurological mouse mutants and the genes of myelin
Authors: Nave K.‐A. 
Published: January 2005

AbstractThe prospect to create mouse mutants of virtually any cloned gene has renewed interest in the genetic analysis of mammalian brain development. A diverse group of spontaneous and engineered mouse mutants, characterized by a defect of myelin formation, has been intensively studied from the morphological to the molecular level. In this system, genetics has been successfully applied to analyze a corresponding set of membrane proteins which help to elaborate a defined structural entity, compact myelin. Shiverer, jimpy, Trembler, and protein zero (P0)‐deficient mice demonstrate the overall function of myelination and have become models for human neurological diseases. They also illustrate some of the problems encountered in defining protein functions from complex mutant phenotypes. © 1994 Wiley‐Liss, Inc.
Fluid‐phase endocytosis of horseradish peroxidase by cerebral endothelial cells in primary culture: Characterization and kinetic analysis
Authors: Noble L. J. , Kalinyak J. E. , Pitts L. H. , Hall J. J. 
Published: January 2005

AbstractEndocytosis of horseradish peroxidase (HRP) was studied in primary cultures of cerebral endothelial cells prepared from 2‐week‐old rats. These cultures were considered “endothelial‐like” on the basis of their ability to internalize acetylated low density lipoprotein. Cellular localization of HRP protein was examined at the light and ultrastructural levels and endocytosis of the protein was evaluated by a colorimetric assay. HRP was localized in discrete cytoplasmic granules by light microscopy. At the ultrastructural level these granules corresponded to pleomorphic membrane‐bound structures that were present throughout the cytoplam. The amount of internalized HRP was directly related to the concentration of the protein in the medium, was not saturable at high concentrations of HRP, and increased with time. Endocytosis proceeded at 37°C, but was abolished at 4°C. In pulse‐chase experiments, the quantity of internalized protein in the cells did not significantly change during the 2 hr chase period. Taken together, these findings suggest that internalization of HRP occurs by fluid‐phase endocytosis, a non‐receptor‐mediated process, and that the protein is stable within an intracellular compartment for at least several hours. © 1994 Wiley‐Liss, Inc.
Presence of axonal paried helical filament‐tau in Alzheimer's disease: Submicroscopic localization
Authors: Bondareff W. , Harrington C. R. , McDaniel S. W. , Wischik C. M. , Roth M. 
Published: January 2005

AbstractWhile normal adult tau protein is found typically in axons, paired helical filament (PHF) tau has been shown immunohistochemically to be in the somatodendritic compartment in Alzheimer's disease (AD). The small amount of PHF‐tau (8‐‐11%) found in white matter with immunochemical methods is shown here by immunoelectron microscopy to be located in axons. It is localized to straight filament variants of PHFs. The small amount of PHF‐tau in white matter, therefore, appears not to result from the contamination of immunochemical preparations but to be an integral constituent of affected axons in AD. © 1994 Wiley‐Liss, Inc.
Solubilization of full‐length amyloid precursor proteins from PC12 cell membranes
Authors: Ripellino J. A. , Vassilacopoulou D. , Robakis N. K. 
Published: January 2005

AbstractThe amyloid β protein (Aβ) of Alzheimer disease (AD) is derived from the proteolytic processing of the amyloid precursor proteins (APP), which are considered type I transmembrane proteins. Production of Aβ from a tranmembrane precursor predicts a proteolytic cleavage within the lipid bilayer, a site relatively inaccessible to proteases. Here we show that incubation of a membrane fraction of PC12 cells at 37°C results in the solubilization of an APP species which migrates on SDS‐PAGE as full‐length APP. The release of this full‐length APP was pH‐dependent with a peak of activity of pH 9.0. At this pH about 19% of the membrane APP was released from the active subcellular fraction. Under the same conditions other transmembrane proteins remained insoluble. Very little APP was solubilized at 4°C. APP solubilization was specifically inhibited by the serine protease inhibitors aprotinin and pefabloc. Other protease inhibitors, including leupeptin and α1‐antitrypsin, had no effect. Several metal cations, including Ca+ + and Zn+ +, also inhibited release of soluble full‐length APP. Low levels of full‐length APP were also detected in both the soluble fraction of PC12 cell extracts and in the media of PC12 cell cultures. These data suggest the involvement of serine protease in the solubilization of membrane, full‐length APP. The release of this APP could provide a soluble substrate for the proteolytic enzymes involved in the production of Aβ.Copyright © 1994 Wiley‐Liss, Inc.
Neurotrophin‐3 enhances neurite outgrowth in cultured hippocampal pyramidal neurons
Authors: Morfini G. , Ditella M. C. , Feiguin F. , Carri N. , Cáceres A. 
Published: January 2005

AbstractLow density dissociated cultures of embryonic rat hippocampal cells were used to study the effects of neurotrophin‐3 (NT‐3) on neuronal morphogenesis. The results obtained indicate that NT‐3 enhances neurite outgrowth and branching; this is a dose‐dependent effect, detected in approximately 50% of the neurons, and prevented by K‐252a, an inhibitor of the trk family of receptor protein kinases. NT‐3 also accelerates the development of neuronal polarity, a phenomenon preceded by a dramatic accumulation of bundles of looped microtubules within axonal growth cones; these microtubule bundles contain tyrosinated, detyrosinated, and acetylated α‐tubulin. Taken collectively, our data suggest that even though the basic shape of hippocampal neurons may be endogenously determined, critical aspects of their morphological development may be modulated by trophic factors such as NT‐3. In addition, our observations suggest that at least some of the neuritogenic effects of NT‐3 involve a stimulation of microtubule assembly and/or transport. Copyright © 1994 Wiley‐Liss, Inc.
Differentiation‐specific demethylation of myelin associated glycoprotein gene in cultured oligodendrocytes
Authors: Grubinska B. , Laszkiewicz I. , Royland J. , Wiggins R. C. , Konat G. W. 
Published: January 2005

AbstractThe methylation status of a 4.4‐kb 5′ end of the myelin‐associated glycoprotein (MAG) gene was assessed in cells with different levels of transcriptional activity of the gene, i.e., liver, brain, O‐2A oligodendrocyte precursors cells, mature oligodendrocytes, and glioma C6 cells. Purified DNA was digested with methylation‐sensitive restriction enzymes, and the cuts were mapped by the indirect end‐labeling technique. The restriction sites within the 4.4‐kb fragment revealed a highly heterogenous methylation pattern among cells and tissues, and liver DNA was the most heavily methylated. Most of the restriction sites were partly demethylated in the nervous system cells. Notably, two adjacent Hha1 sites at +94 and +96 were fully methylated in liver, but partially demethylated in the brain, OL, and O2A. Two Hpa2 site located at −1836 and at −39 were progressively demethylated in oligodendrocyte lineage cells, indicating specific hypomethylation associated with the oligodendrocytic differentiation. Most of the restriction sites were weakly methylated in the DNA from neoplastic C6 cells, although the Hha1 sites were fully methylated. No clear‐cut correlation between the extent of CpG dinucleotide methylation and the chromatin conformation was found. For example, out of four heavily methylated sites only two comapped with MNase hypersensitive sites. Also, the −1836 Hpa2 site whose demethylation is concomitant with oligodendrocytic differentiation seems to be localized within precisely positioned nucleosomal arrays of the MAG gene chromatin.The results indicate that the MAG gene undergoes progressive demethylation concomitant with the oligodendrocyte differentiation/maturation. However, certain CpG dinucleotides remain heavily methylated even in the fully active gene in mature oligodendrocytes, indicating that they may be essential in maintaining proper chromatin structure. © 1994 Wiley‐Liss, Inc.
Proliferation and differentiation of fetal human oligodendrocytes in culture
Authors: Satoh J. , Kim S. U. 
Published: January 2005

AbstractPhenotypic expression and proliferative capacity of the cells of oligodendrocyte lineage were investigated in primary cultures isolated from fetal human brains of 12–15 weeks' gestation using double immunolabeling with Ranscht‐monoclonal antibody (R‐mAb) or O4 and antibromodeoxyuridine (BrdU) antibody. Cultured cells of oligodendrocyte lineage consisted of a major population of R‐mAb+O4− cells and minor populations of R‐mAb−O4+ and R‐mAb+O4+ cells. Most of the R‐mAb+O4− cells exhibited a uni‐, bi‐, or tripolar immature morphology, while the majority of the R‐mAb+O4+ cells exhibited a multipolar mature morphology. R‐mAb−O4+ cells contained a mixture of immature and mature cell types. When incubated in serum‐free culture medium containing BrdU for 4 days, 42% of total oligodendrocytes expressed nuclear BrdU immunolabeling. R‐mAb+ cells exhibited a higher degree of BrdU immunolabeling, indicating that they have greater capacities for proliferation than O4+ cells. The large majority of BrdU+ cells exhibited an immature morphology. Inclusion of insulin, insulin‐like growth factor (IGF)‐I, basic fibroblast growth factor (bFGF), or fetal bovine serum in culture medium did not stimulate proliferation of oligodendrocytes, while platelet‐derived growth factor (PDGF) of PDGF plus bFGF increased the number of R‐mAb+BrdU+ and O4+BrdU+ cells over control, even though the results were not statistically significant. In addition, insulin and IGF‐I induced a 3‐fold increase in the number of R‐mAb+O4+ cells, indicating that they promoted differentiation of oligodendrocytes. The present study indicates that fetal human oligodendrocytes in culture exhibit a considerable degree of proliferative capacity without requirement of exogenous growth factors and that both insulin and IGF‐I promote their differentiation. © 1994 Wiley‐Liss, Inc.
Prolonged alkylcatechol‐induced expression of c‐jun proto‐oncogene followed by elevation of NGF mRNA in cultured astroglial cells
Authors: Omae F. , Katsumata T. , Sakuma M. , Furukawa Y. , Furukawa S. 
Published: January 2005

AbstractWe have already shown that alkylcatechol markedly enhances synthesis/secretion of nerve growth factor (NGF) in cultured mouse fibroblasts and astroglial cells through immediate accumulation of NGF mRNA and that the stimulatory effect of alkylcatechol on NGF synthesis/secretion is synergistically enhanced by the coadministration of phorbol 12‐myristate 13‐acetate (PMA). The stimulatory effect on NGF mRNA expression of astroglial cells in culture by 4‐methylcatechol (MC), an alkylcatechol, and/or PMA was blocked by treatment of the cells with cycloheximide, suggesting de novo synthesis of some cellular protein(s) is essential for the observed increase in the NGF mRNA level. The exposure to MC and/or PMA caused a rapid increase in c‐fos mRNA content, which was immediately followed by an increase in c‐jun mRNA, prior to NGF mRNA elevation. The expression of c‐fos mRNA was transiently enhanced in all cases of the treatment with MC and/or PMA. The c‐jun mRNA expression was also observed transiently when the cells were treated with PMA alone, while the expression of c‐jun mRNA was pronounced and long‐lasting after the treatment with MC, which was much further enhanced by the coadministration of PMA. The result that the profile of the change in c‐jun mRNA expression resembled that in NGF mRNA expression suggests that the increase in c‐jun mRNA is responsible for the subsequent increase in NGF mRNA after MC treatment. The cotransfection of mouse astroglial cells with expression plasmids of c‐fos and/or c‐jun and NGF promoter gene showed that simultaneous expression of both c‐fos and c‐jun genes was necessary to enhance NGF promoter activity. These results suggest that alkylcatechol induces NGF mRNA by means of transient induction of c‐fos mRNA and long‐lasting induction of c‐jun mRNA. © 1994 Wiley‐Liss, Inc.
Regional CNS uptake of blood‐borne nerve growth factor
Authors: Loy R. , Taglialatela G. , Angelucci L. , Heyer D. , Perez‐Polo R. 
Published: January 2005

AbstractNerve growth factor (NGF), in addition to being a neurotrophic substance, has effects on the endocrine and immune systems. For example, intravenous injection of NGF results in a cascade of events leading to an increase in glucocorticoid secretion. While this response appears to be mediated centrally, there has been no evidence that circulating NGF has access to the CNS. Using intravenous injections of 125I‐NGF, we find specific uptake at 1 hr but none at 6 hr, into homogenates of the basal forebrain, cerebellum, frontal cortex, hippocampus, and olfactory bulb. By autoradiography, uptake is localized to circumventricular organs, deep layers of the cerebellum, and all layers of the hippocampal region CA1, but not the dentate gyrus. Thus, uptake of blood‐borne NGF could affect the hypothalamic‐pituitary‐adrenal axis via binding to NGF receptors present in the hippocampus. However, the sources of endogenous NGF, the mechanism of access through the blood‐brain barrier, the eventual fate of NGF entering from the blood, and the physiological significance of this uptake remain to be elucidated. © 1994 Wiley‐Liss, Inc.
Calpain inhibitors block Ca2+‐induced suppression of neurite outgrowth in isolated hippocampal pyramidal neurons
Authors: Song D.‐K. , Malmstrom T. , Kater S. B. , Mykles D. L. 
Published: January 2005

AbstractCa2+ is an important regulator of neurite elongation and growth cone movements but the mechanism(s) mediating these Ca2+‐dependent effects is nuclear. Since cytoskeletal proteins are rapidly degraded by Ca2+‐dependent proteinases (calpains) in vitro and in vivo, we investigated whether Ca2+‐induced pruning or regression of neuronal processes is mediated by calpains. Isolated hippocampal pyramidal‐like neurons were cultured and the ability of the membrane‐permeable calpain inhibitors ethyl(+)‐(2S,3S)‐3‐[(S)‐methyl‐1‐(3‐methylbutylcarbamoyl)‐butylcarbamoyl]‐2‐ oxiranecarboxylate (EST) and carbobenzoxyl‐valyl‐phenylalanyl‐H (MDL 28170) to block the Ca2+ ionophore A23187‐induced suppression in neurite outgrowth was investigated. Addition of 100 nM A23187 to the culture medium resulted in a retraction of dendrites without altering axonal elongation. The addition of 300 nM A23187 to the culture medium resulted in a significant decrease in the rate of axonal elongation as well as a retraction of dendritic processes. Administration of EST (5 or 20 m̈M) to the culture medium completely blocked the pruning effect of 100 nM A23187 on dendrites and of 300 nM A23187 on axons, while EST alone did not significantly affect neurite outgrowth rate. MDL 28170 (20 m̈M) showed the same effect as EST in preventing ionophore‐induced pruning of dendrites and axons at 100 and 300 nM concentrations, respectively, of A23187. EST (20 m̈M) did not block the A23187‐induced rise of [Ca2+]i as measured with fura‐2. These results suggest that calpains play a role in Ca2+‐induced pruning of neurites in isolated hippocampal pyramidal neurons. © 1994 Wiley‐Liss, Inc.
Tau‐like immunoreactivity in Alzheimer and control skin fibroblasts
Authors: Matsuyama S. S. , Bondareff W. 
Published: January 2005

AbstractThe presence of the microtubule‐associated protein tau in skin fibroblasts derived from Alzheimer patients and normal controls was investigated using a panel of well‐characterized anti‐tau antibodies against epitopes spanning the tau protein from the amino to the carboxyl end. The antibodies immunolabeled a fine, fibrillar cytoplasmic network in all skin fibroblasts. Disruption of the microtubule network with colchicine did not affect the immunolabeling of the fibrillar network nor did treatment with cytochalasin B known to disrupt the microfilament network. Immunoelectron microscopy with the antitau antibodies revealed colocalization of the label with the 10 nm intermediate filaments. Furthermore, immunoblots found no reactivity against purified vimentin, suggesting that the antibodies recognize an intermediate filament‐associated protein. The findings indicate the presence of tau or a protein with considerable homology to tau in fibroblasts associated with intermediate filaments and not microtubules. © 1994 Wiley‐Liss, Inc.
Retardation of neuritic outgrowth and cytoskeletal changes accompany acetylcholinesterase inhibitor treatment in cultured rat dorsal root ganglion neurons
Authors: Dupree J. L. , Bigbee J. W. 
Published: January 2005

AbstractOver the past two decades acetylcholinesterase (AChE) has been shown to be present in numerous non‐cholinergic and non‐cholinoceptive tissues. Interestingly, transient expression of AChE in developing nervous tissue corresponds temporally with neuronal migration and neuritic outgrowth. This observation has led our laboratory to investigate a possible novel, non‐cholinergic role for AChE in the development of the nervous system. In a previous study, we demonstrated that the activity of AChE in cultured dorsal root ganglion neurons (DRGN) can be modulated by the substratum. In our current study, we have examined the effects of AChE inhibitor treatment on neuritic outgrowth on the highly permissive substratum MatrigelTM and the less permissive substratum Collagen Type I. DRGN received serial dilutions of the AChE‐specific inhibitor 1,5‐bis‐(4‐allyldimethylammoniumphenyl) pentan‐3‐one dibromide (BW284c51) ranging from 10−4 to 10−7 M. Results showed that neuritic outgrowth was significantly reduced in DRGN grown on MatrigelTM at 10−5 and 10−4 M BW284c51, while outgrowth on Collagen Type I was significantly reduced at 10−6, 10−5, and 10−4 M concentrations of BW284c51. Inhibitor treatment did not affect cell survival and neuritic outgrowth from BW284c51‐treated cells recovered to control levels after removal of the inhibitor from the medium. In addition, massive spiraling accumulations of 10 nm filaments were observed in the cell bodies of treated neurons, which resemble neurofibrillary inclusions observed in neuropathological diseaes such as Pick's disease. This study demonstrates that AChE inhibitor treatment retards neuritic outgrowth and neuronal migration of cultured DRGN which is accompanied by cytoskeletal abnormalities in the cell body. These data further suggest a novel, non‐cholinergic role for AChE in neural development and regeneration. © 1994 Wiley‐Liss, Inc.
Dopamine and serotonin turnover rate in the retina of rabbit, rat, goldfish, and Eugerres plumieri: Light effects in goldfish and rat
Authors: Lima L. , Urbina M. 
Published: January 2005

AbstractThe concentration of dopamine, and its metabolites 3,4‐dihydroxyphenylacetic and homovanillic acids, as well as serotonin and its metabolite 5‐hydroxyindoleacetic acid, were determined in the retina of two teleosts, C. auratus (goldfish) and E. plumieri (mojarra), and two mammals, R. norvegicus (rat) and O. cuniculus (rabbit). The turnover rate of these monoamines were investigated in the four species by the calculation of the ratio monoamine/metabolite as an indirect index, and in goldfish and rat by the inhibition of the synthesis with α‐methyl‐p‐tyrosine or p‐chlorophenylalanine, by the increase in dopamine or serotonin by the corresponding precursors, 3,4‐dihydroxyphenylalanine or 5‐hydroxytryptophan, and by inhibition of monoaminooxidase with pargyline. The modulation by light and dark stimulation was studied in the goldfish and the rat. Differences in the concentration and turnover rate were observed among the species. Serotonin concentration was higher in the teleosts. The administration of inhibitors of dopamine and serotonin synthesis differentially decreased the levels of the monoamines in the retina of goldfish and rat. The rate of formation of dopamine and serotonin by the corresponding precursors was much higher in the goldfish than in the rat. Pargyline administration decreased 3,4‐dihydroxyphenylacetic and 5‐hydroxyindoleacetic acids at different rates and time dependency in the retina of goldfish and rat. Dopamine and serotonin concentration did not exhibit high modifications by the inhibitor, suggesting the function of regulatory mechanisms or additional effect of pargyline at other sites different from monoaminooxidase. Light stimulation decreased the ratios of dopamine and its metabolites in the retina of goldfish, but not in the rat, probably by a greater release of dopamine with lower uptake capacity in the latter. Goldfish or rat retinal serotonin did not change by light exposure. Homovanillic acid was not detected in either type of retina after the dark period. In the goldfish, there was an increase in dopamine/3,4‐dihydroxyphenylacetic acid ratio by the darkness; in the rat, this ratio decreased, which might be related to the release of dopamine. Retinal serotonin turnover rate was accelerated in the goldfish by dark stimulation. The present comparative results support a differential regulation of monoamine levels among species, and will be useful for further characterization of the regulatory mechanisms related to light and dark exposure. © 1994 Wiley‐Liss, Inc.