bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modifications of synaptosomal plasma membrane protein composition in various brain regions during aging
Authors: Ragusa Nicolo' , Villa Roberto F. , Magri' Grazia , Ingrao Francesca , Gorini Antonella , Turpeenoja Leena , Stella A.M. Giuffrida 
Published: April 2003

AbstractThe age‐dependent modifications of synaptosomal plasma membrane protein composition in three different rat brain regions (cerebral cortex, cerebellum and striatum) at various ages (4,12 and 24 months) were studied. The proteins were separated by gel‐electrophoresis and the quantity of the different polypeptides was determined densitometrically from the stained gels.In the three brain regions examined several age‐related modifications in the amount of the synaptosomal plasma membrane proteins were observed. In particular a significant decrease in the content of some synaptosomal plasma membrane proteins at 24 months of age was found. The agerelated modifications in the protein composition of synaptosomal plasma membrane may cause changes in many brain functions, such as neurotransmission, ionic transport and enzyme activities.Particularly interesting is the decrease of a protein with 18 kDa mol. wt. This protein has been identified as calmodulin by immunoblotting assay. The decrease in the amount of this protein may be correlated to the impairment of several Ca2+‐ requiring processes in the aging brain.
Development of membrane currents in mammalian neuroventricular cells from the early neural tube stage in vitro: Aspects of the neuronal lineage
Authors: Wiedehage Johannes , Schmidtmayer Johann , Buse Eberhard 
Published: April 2003

AbstractNeuroepithelial cells from the murine brain anlage at the early neural tube stage (embryonic day 9½, stage 15) were cultured. Their morphology and the development of membrane currents were studied during 2 weeks in culture. Immediately after dissociation the cells were equal in shape and no morphological or ultrastructural differences were evident. Patch‐clamp measurements within the first 2 h, however, showed different membrane properties. Either sodium inward currents or potassium outward currents were observed in these undifferentiated cells, but no combined inward and outward currents were found. This would mean that some of the neuroventricular cells, but obviously not all of them, display neuronal membrane properties (sodium currents) in the immediate post neural plate stage. After 1 day, developing neurons could be identified morphologically by neurotubuli and process formation. The transformation of these cells into neurons was electrophysiologically characterized by an increasing sodium channel density and the expression of various kinds of potassium channels. After 4 days the vast majority of the neurons was electrically excitable, i.e. they could generate action potentials. The standard electrical profile at this time was characterized by a sodium inward current followed by a delayed potassium outward current. In the following days the complexity of membrane currents increased in some neurons by the emergence of transient potassium currents. After 2 weeks in culture different neuronal phenotypes could be identified.
Morphometric and time lapse analyses of rapid‐onset neurites stimulated by cycloheximide in NG108‐15 cells
Authors: Smalheiser Neil , Rossulek Michelle 
Published: April 2003

AbstractWe previously reported that the laminin‐induced outgrowth of neurites in the first 4 hr after plating (‘rapid‐onset neurites’) is markedly stimulated by inhibitors of protein and RNA synthesis, including cycloheximide, puromycin and actinomycin D. Our original interpretation of this finding was that inhibiting protein synthesis led to metabolic changes in the cell which converged upon the intracellular pathway used by laminin to stimulate neurite formation. Alternatively, Preston et al. (1987, Proc. natn. Acad. Sci. U.S.A. 84, 5247–5251) suggested that cycloheximide acts by inhibiting neurite retraction. In order to resolve these conflicting interpretations, we decided to re‐examine the effects of cycloheximide using time lapse analyses of NG108‐15 cells grown on laminin, together with morphometric analyses of cultures fixed at 1.5 or 3 hr after plating. Cycloheximide was found to cause both an increase in neurite initiation within the first 1.5 hr after plating, and a decrease in the occurrence of neurite retractions between 1 and 3 hr. Investigators should be aware of the effects of biosynthetic inhibitors on neurite growth, since these agents are employed widely in studies of cultured neural cells, particularly those involving receptor metabolism and phenotypic differentiation.
Perinatal morphine exposure alters peptidergic development in the striatum
Authors: Tenconi Beatrice , Donadoni Maria Luisa , Finco Cristina , Germani Elena , Malosio Maria Luisa , Di Giulio Anna Maria , Mantegazza Paolo , Gorio Alfredo 
Published: April 2003

AbstractIt has been reported that perinatal exposure to opiates affects mRNA synthesis, body growth and brain development in mammals, including humans. We have observed that morphine administration in drinking water during the perinatal period alters peptide development in the striatum of the rat. There is a marked increase in substance P and met‐enkephalin content, the latter is maintained even at 30 days postnatally. The transient increase or earlier maturation of substance P content is correlated by a more precocious axon terminal organization as revealed by immunocytochemical staining. The increased metenkephalin content is correlated by a higher abundance of preproenkephalin A mRNA and this correlation is particularly evident at 15 days postnatally. At earlier times both northern blotting and in situ hybridization techniques fail to show any significant difference between control and morphine exposed rats, likely because the peptide content is not very different in the two groups or at least the gap is not as wide as at later times.
Aging‐related changes in IGF‐II and c‐fos gene expression in the rat brain
Authors: Kitraki Efthimia , Bozas Evangelos , Philippdis Helen , Stylianopoulou Fotini 
Published: April 2003

AbstractThe protein products of growth factor genes such as IGF‐II and cellular oncogenes such as c‐fos are believed to be necessary for the support of normal neuronal function. Steady‐state levels of c‐fos and IGF‐II mRNA were determined in the brain of young and old rats, using Northern analysis. Both RNAs were found to be decreased in the brain of aged rats. Age‐related decrease was detected in the hippocampus, hypothalamus, striatum, cerebral cortex and cerebellum, for IGF‐II mRNA, and in the cerebral cortex and cerebellum for c‐fos mRNA. Furthermore, changes in the degree and pattern of DNA methylation were noted at both gene loci, in the aged rat brain. Our results could reflect changes at the genomic level possibly related to the process of aging and the accompanying decline in brain function.
Voltage sensitive calcium channels mark a critical period in mouse neurodevelopment
Authors: Litzinger M.J. , Grover B.B. , Saderup S. , Abbott J.R. 
Published: April 2003

AbstractVoltage sensitive calcium channel (VSCC) probes 125I‐ω‐GVIA Conotoxin (ω‐GVIA), (+)‐[5‐methyl‐3H]‐PN200‐110 (3H‐PN200), and 3H‐Nimodipine were bound to developing Swiss Webster mouse whole brain from postnatal days 3 to 24. 125I‐ω‐GVIA binding, thought to be presynaptic, showed a 50% increase between days 11 and 14. 3H‐dihydropyridine binding, thought to be postsynaptic, showed spike patterns when measured developmentally. 3H‐PN200 binding showed a >150% increase between days 11 and 15. 3H‐Nimodipine binding showed a >100% increase between days 11 and 14. Depolarization‐induced 45Ca fluxes also increased between days 8 and 16 by >500%. The dramatic increases indicated by these binding data correspond to a critical period described by Himwich (Int. Rev. Neurobiol. 4, 117, 1962) between postnatal days 11 and 14 in Swiss Webster mice; during this critical period, dendrites exhibit rapid outgrowth, sensory modalities come on line, EEG patterns mature, and the cortex reaches adult proportions. We conclude from these data that the increase in VSCC activity parallels a critical period in the development of the central nervous system in Swiss Webster mice.
Migration of purified embryonic motoneurons grafted into adult mouse CNS
Authors: Ruiz‐Flandes P. , Demierre B. , Mattenberger L. , Kato A.C. 
Published: April 2003

AbstractEmbryonic motoneurons were fluorescently‐labelled with carbocyanine (diI) by means of retrograde transport and then grafted into the adult mouse spinal cord (L2) and brain (striatum) for 2–10 weeks. The motoneurons were grafted either following purification on the fluorescence‐activated cell sorter or in the presence of embryonic glial cells and interneurons from the spinal cord. In both conditions of grafting, motoneurons were found to survive and develop in both grey and white matter and were found to migrate long distances in both regions of the central nervous system.Migration of neurons after grafting remains a controversial issue, therefore we have discussed the work of other groups that have described the same phenomenon.
Co‐expression of GFAP and vimentin in astrocytes proliferating in response to injury in the mouse cerebral hemisphere. A combined autoradiographic and double immunocytochemical study
Authors: Janeczko Krzysztof 
Published: April 2003

AbstractChanges in the distribution of proliferating astrocytes expressing glial fibrillary acidic protein (GFAP) and/or vimentin were examined in the injured cerebral hemisphere in adult mice. The injury was followed by [3H]thymidine injections at different time intervals. The brain sections were doubly immunostained for GFAP and vimentin and subjected to autoradiography. In that way three cell types were distinguished immunocytochemically: (1) astrocytes co‐expressing glial fibrillary acidic protein (GFAP) and vimentin (2) astrocytes expressing only GFAP (3) astrocyte‐like cells expressing vimentin. Thereafter, numbers of immunopositive and autoradiographically labelled cells and their locations within the region of injury were recorded at each stage of the experiment. Two hours as well as 1 day after the injury proliferation of GFAP‐positive astrocytes and of those co‐expressing GFAP and vimentin could only be seen as statistically insignificant phenomena. On day 2 the reactive proliferation of each immunocytochemically defined cell type was already maximal, then gradually decreased and its last signs were recorded on day 8. On day 2, among all the proliferating GFAP‐positive astrocytes, 67.2% were also vimentin‐positive. Later, the proportion declined to 50.7% and 38.5% on days 4 and 8, respectively. The labelled astrocyte‐like vimentin‐positive cells were located closest to the lesion margins. In comparison, the astrocytes co‐expressing GFAP and vimentin and those expressing exclusively GFAP, occupied regions progressively farther from the lesion site. At the initial stages of the response to injury, vimentin expression in cells starting their reactive proliferation did not precede the expression of GFAP. This was considered as an argument against a hypothesis that reactive astrocyte division induces a two‐stage increase in the cytoskeletal protein level in which synthesis of vimentin precedes that of GFAP.
CSF‐1 expression is upregulated in astrocyte cultures by IL‐1 and TNF and affects microglial proliferation and morphology in organotypic cultures
Authors: Shafit‐Zagardo Bridget , Sharma Nishi , Herman Joan W. , Bornstein Murray B. , Brosnan Celia F. 
Published: April 2003

AbstractAstrocytes produce factors that control the growth and differentiation of many cell types within the CNS as well as play a role in the generation of the immune response. The extent to which these two functions interact has received less attention. We now report that astrocyte cultures established from rat brain endogenously express mRNA and low levels of secreted biologically active protein for the monocyte growth and differentiation factor colony stimulating factor‐1 (CSF‐1). Exposure of astrocytes to interleukin‐1 (IL‐1) and/or tumor necrosis factor (TNF) upregulated the expression of CSF‐1 mRNA and protein. Following treatment with 100 U/ml of TNF, IL‐1, or TNF+IL‐1, maximum CSF‐1 mRNA expression was observed at 3 hr. In the presence of IL‐1 an increase in biologically active CSF‐1 was detected in the astrocyte conditioned medium at 6 hr. These data indicate that the expression of CSF‐1 by astrocytes can be modulated by exposure to the cytokines IL‐1 and TNF. To determine whether CSF‐1 provides a mitogenic signal for microglia during development, mouse spinal cord organotypic cultures were exposed to recombinant mouse CSF‐1 (rmCSF‐1), resulting in proliferation of microglia by 7 days and an increase in the number of ramified microglia over ameboid microglia by 14 days.
Effects of hyperactivity of the maternal hypothalamic‐pituitary‐adrenal (HPA) axis during pregnancy on the development of the HPA axis and brain monoamines of the offspring
Authors: Fameli M. , Kitraki E. , Stylianopoulou F. 
Published: April 2003

AbstractOffspring of mothers with adrenal hyperactivity during pregnancy have been reported to have changes in brain monoamines and altered emotional, reactive, sexual and maternal behavior. Since the hypothalamic‐pituitary‐adrenal (HPA) axis is known to be involved in the expression of such behaviors and is itself under monoaminergic control, we examined the development of the HPA axis and brain monoamines in pups whose mothers had adrenal hyperactivity, reflecting administration of ACTH during the last third of their pregnancy. The adrenals of the experimental animals weighed less and had aberrant morphology. The abnormal histology was more pronounced in the adrenals of the experimental females than of the males, suggesting that females were more vulnerable to the prenatal treatment. In both experimental males and females, basal plasma corticosterone levels were higher compared to the controls, while after exposure to stress, experimental animals attained lower plasma corticosterone levels than the controls. In the brain of the experimental animals, dopaminergic activity appeared to be decreased, while serotonergic activity increased. Our results indicate that the prenatal treatment affected brain development in the offspring and as a consequence programmed the developing HPA axis in such a way as to hyperfunction under basal conditions, leading to its exhaustion and its inability to react properly to stress.
Expression of neurotrophin genes in human fibroblasts: Differential regulation of the brain‐derived neurotrophic factor gene
Authors: Cartwright M. , Mikheev A.M. , Heinrich G. 
Published: April 2003

AbstractBrain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin‐3 (NT‐3) are structurally related survival and differentiation factors for distinct sets of peripheral and central neurons. We previously reported that BDNF and NGF gene expression are differentially regulated in mouse L929 fibroblasts. Here we examine expression of these three neurotrophins in human fibroblasts. Northern blots detected BDNF and NT‐3 mRNAs in fibroblasts derived from lung (WI‐38), calvarium and foreskin. WI‐38 cells and foreskin fibroblasts expressed 1.6 kb as well as 4 kb BDNF mRNAs whereas only the smaller BDNF mRNA was detected in calvarium fibroblasts. NGF mRNA was present in foreskin and calvarium but not lung fibroblasts. In WI‐38 cells serum treatment increased levels of BDNF mRNA within 2 hr. Cycloheximide did not inhibit the increase. Treatment with 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA) transiently suppressed BDNF mRNA. Treatment with both serum and TPA first stimulated and then transiently suppressed BDNF mRNA. TPA and/or serum did not significantly affect BDNF mRNA in calvarium fibroblasts. These results show that human fibroblasts derived from different tissues express and regulate neurotrophin genes differentially.
Choroid coat extract and ciliary neurotrophic factor strongly promote neurite outgrowth in the embryonic chick retina
Authors: Carri Nestor G. , Richardson Peter , Ebendal Ted 
Published: April 2003

AbstractPrevious studies have shown that extracts from the target optic tectum stimulate neurite outgrowth from retinal explants. The present study indicates that the choroid coat is an even richer source of retinotrophic activity. We thus studied the effects of recombinant rat ciliary neurotrophic factor (CNTF) on primary cultures of dissociated chick ciliary ganglion neurons and retinal explants for a comparison with choroid coat extract from the E 18 chick. For our assays, E9 ciliary neurons were incubated in collagen gels and retinal explants were cultured on collagen gels with the addition of the trophic factors and maintained for two or four days. Survival of ciliary neurons per area as well as maximal neurite length in retinal cultures were determined. Growth responses occurred in a dose‐dependent manner both to CNTF and choroid extract. Immunofluorescence examination of cells and developing processes showed 200 kdal neurofilament positivity demonstrating that the cells studied were neurons with neurites. It is concluded that a trophic activity of the choroid as well as the recombinant CNTF stimulate retinal neuron survival and neurite extension. The results suggest that CNTF may have developmental functions in the establishment of the visual pathways.
A reverse transcription‐polymerase chain reaction study of p75 nerve growth factor receptor gene expression in developing rat cerebellum
Authors: Chu‐Kuang Chen , Kinsman Stephen L. , Holtzman David M. , Mobley William C. , Johnston Michael V. 
Published: April 2003

AbstractThe actions of the neurotrophins are mediated through specific receptors. Nerve growth factor (NGF), the prototypic neurotrophin, binds to receptors of both high and low affinity. A protein 75 kDa in size (p75NGFR) binds NGF, as well as brain‐derived neurotrophic factor and neurotrophin 3, with low affinity. Recent investigations suggest that this protein may also be a component of the high affinity NGF receptor complex. To study gene expression of the p75NGFR molecule, we used a sensitive reverse transcription‐polymerase chain reaction (RT‐PCR) assay to measure levels of its messenger RNA (mRNA) in small samples of total RNA. The assay is based on using a shortened p75NGFR cRNA as an internal RNA standard to control for variability in reverse transcription and polymerase chain amplification. We measured p75NGFR mRNA levels in the rat cerebellum during ontogeny to further study the transient developmental increase in receptor gene expression known to occur in this brain region during the early postnatal period. We found that p75NGFRmRNA levels were most abundant at postnatal day 2, and then declined to lower levels throughout postnatal development and in the adult. Northern blot analysis of the same total RNA samples used in our RT‐PCR assay verified that p75NGFR expression is highest in the early postnatal period. These results confirm those of previous studies accomplished with much larger amounts of RNA using ribonuclease protection or northern blot assays. The use of an RT‐PCR assay that utilized an internal standard also controls against changes in RNA complexity which can affect the measurement of message abundance across developmental stages. These results again suggest that p75NGFR may play an important role in the postnatal development of cerebellum in rats
Olfactory ensheathing glia and platelet‐derived growth factor B‐chain reactivity in the transplanted rat olfactory bulb
Authors: Kott J.N. , Westrum L.E. , Raines E.W. , Sasahara M. , Ross R. 
Published: April 2003

AbstractUsing a monoclonal antibody against the B‐chain of platelet‐derived growth factor as a marker, we have examined the behavior of olfactory ensheathing glia in the normal and transplanted rat olfactory bulb. In the normal postnatal olfactory bulb, these glia are found to ensheath the bundles of incoming primary olfactory nerve fibers as well as those in the olfactory nerve layer. Olfactory marker protein antibody was used to identify the olfactory nerve proper. Within the transplant, the same glia: (1) ensheath bundles of both primary olfactory and non‐primary olfactory axons, (2) ensheath axonal bundles deep within the donor tissue, and (3) eventually permit radiation of individual axons from bundles to surrounding neuropil.We believe that ensheathing glia (being rich in growth‐related factors and extracellular matrix molecules) may be useful in providing trophic support and guidance for the reconstruction of developmentally or traumatically damaged neuronal pathways not directly related to the olfactory system. The evidence presented here indicates that ensheathing glia are capable of existing in deep brain areas and ensheathing other than primary olfactory axons. The special molecular characteristics of these glia along with the morphological findings presented here provide a foundation for further studies of these unique glia and their potential utility in the restoration of damaged neural pathways.
Different ω‐conotoxins mark the development of Swiss Webster mouse cortex suggesting N‐Type voltage sensitive calcium channel subtypes
Authors: Abbott J.R. , Litzinger M.J. 
Published: April 2003

Abstractω‐GVIA conotoxin has been used to mark presynaptic N‐type voltage sensitive calcium channels (VSCC).3,13,19,21–23 Litzinger et al.9 used ω‐conotoxin binding to describe a critical period of neurodevelopment in Swiss Webster mice between postnatal days (PND) 11 and 14, which appears to be important to the initiation of proper final development of the central nervous system. In this study, we compare how three different ω‐conotoxins (i.e. GVIA from Conus geographus, MVIIA from Conus magus, and RVIA from Conus radiatus) mark N‐type VSCC during this critical period in Swiss Webster mouse cortex. 125I‐GVIA was bound to Swiss Webster mouse cortex synaptosomal membrane fractions at postnatal days 8 and 14. 125I‐GVIA binding displacement curves were obtained by incubating membranes with increasing concentrations of unlabeled GVIA, MVIIA, and RVIA. Displacement curves and IC50 were calculated for each of these three ω‐conotoxins, and then compared. At PND 14, GVIA, MVIIA and RVIA were able to displace greater than 95% of 125I‐GVIA binding. At PND 8, however, MVIIA was only able to displace 83% of 125I‐GVIA binding, and RVIA was only able to block 84%. The IC150 does not appear to change significantly during this period of development for any of the ω‐conotoxins. The inability of MVIIA and RVIA to completely block 125I‐GVIA binding in pre‐critical period Swiss Webster cortex denotes an alteration in the composition of N‐type VSCC binding sites. With this data, we have suggested the presence of subtypes of the N‐type VSCC in the cortex of pre‐critical period Swiss Webster mouse.
IMPROVED DETECTION OF BIFURCATIONS IN LARGE NONLINEAR SYSTEMS VIA THE CONTINUATION OF INVARIANT SUBSPACES ALGORITHM
Authors: FRIEDMAN M. J. 
Published: April 2003

The Continuation of Invariant Subspaces (CIS) algorithm [Demmel et al., 2001; Dieci & Friedman, 2001] produces a smooth orthogonal similarity transformation to block triangular form of a parameter dependent matrix A(s). The CIS algorithm is an adaptation of an iterative refinement technique for improving the accuracy of computed invariant subspaces. On the basis of the CIS algorithm, new test functions are defined for an improved, more reliable detection of bifurcations in problems with simple bifurcations near multiple bifurcations, problems with multiple bifurcations, and problems with symmetries. Illustrative examples are given.