bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium‐dependent regulation of phospholipase A2 and its inhibitors, including tetracaine, for acetylcholine receptor cluster formation in mouse myotubes co‐cultured with spinal cord explant
Authors: Kimura M. , Kimura I. , Shikada A. , Takahashi K. 
Published: April 2003

AbstractRegulatory effects of phospholipase A2 (PLA2) on acetylcholine receptor (AChR) cluster formation were investigated in developing mouse myotubes co‐cultured with spinal cord explant, using quinacrine, cortisone, tetracaine and related agents. AChR was visualized using fluorescence‐conjugated α‐bungarotoxin. Peak fluorescence intensity and total fluorescence within the fluorescence stain were measured as indices of AChR cluster formation and AChR content, respectively. Both indices were gradually increased from day 9 to 13 in culture. PLA2 (0.2–1.0 μg/ml), melittin (10 μg/ml) and arachidonic acid (100 μM), added to the culture medium from the second day, clearly inhibited both indices at days 11 and 13, whereas the addition of phospholipase C (1 μg/ml) inhibited peak fluorescence but did not affect total fluorescence. The co‐existence of PLA2 with its inhibitors—quinacrine (3 μM), cortisone (0.01 μM) and tetracaine (30 μM)—significantly overcame the PLA2‐induced inhibition of both indices.The elevation of calcium ion concentrations from 2.9 to 10 mM abolished the increase of both indices. Ouinacrine (10 μM), cortisone (0.1 μM) and tetracaine (100 μM) alone similarly inhibited both fluorescence indices. The addition of EGTA (2 mM) from day 8 overcame tetracaine‐induced inhibition but not quinacrine‐ or cortisone‐induced inhibition. These results suggest that the formation of AChR clusters in developing myotubes is negatively controlled by endogenous PLA2 activity. This overcoming of PLA2‐induced inhibition by tetracaine may be dependent on calcium ion mobilization, whereas that by quinacrine and cortisone may not.
Transplantation immunobiology in relation to neural grafting: Lessons learned from immunologic privilege in the eye
Authors: Streilein J. Wayne 
Published: April 2003

AbstractThe principles of transplantation immunobiology are described and discussed in terms of their applicability to neural grafting, a newly emerging field dedicated to the ultimate goal of reconstituting central nervous system deficits with normally functioning tissue replacements. Unique anatomic and physiologic features of the eye, which are responsible for the phenomenon of immunologic privilege, are compared with the brain and considered in terms of their relationship to the principles of transplantation. The existence of immune privilege in the brain and the newly acquired understanding of immunologic privilege in the eye may offer strategies by which neural grafters can achieve significantly greater graft acceptance.
Effects of injecting antibodies to mouse nerve growth factor into the chick embryo
Authors: Dimberg Yvonne , Ebendal Ted 
Published: April 2003

AbstractThe function of NGF in chick embryos was studied by injecting antibodies to mouse nerve growth factor (NGF). The uptake of mammalian antibodies into the 8‐ to 15‐day‐old chick embryo was followed by an enzyme‐linked immunoassay. Normal rabbit antibodies (250 μg) were administered to the yolk, of which less than 5% was found in the embryo (300 ng of IgG per g wet wt of embryo). The concentration was proportionally lower when 100 μg anti‐NGF antibodies were injected (40 ng/g). The concentration of anti‐NGF antibodies was 1.5 times higher following injection directly into the body of the embryos. The effects of injecting antibodies at days 3–7 were studied in 10‐day‐old embryos by measuring the diameter frequencies of neurons in sympathetic and sensory ganglia. In comparison with controls, significantly smaller neurons were found in the sympathetic ganglia in embryos directly injected with anti‐NGF. In the spinal ganglia, distribution of neuron diameters did not differ between anti‐NGF‐treated embryos and controls. Finally, the ability of different antibodies to mouse NGF to inhibit the in vitro activity of recombinant chick NGF was investigated. Total block was found at 1000–2000 ng of IgG per ml for most of the antibodies tested, levels not reached when injecting the embryo with antibodies to NGF. We conclude that the main reason for the limited effects in chick embryos by injection of NGF antibodies is due to the low levels of penetration of the anti‐NGF IgG into the embryo.
Influence of GM1 gangliosides on the growth of cultured rat embryonic serotonergic neurons
Authors: Marlier L. , Poulat P. , König N. , Drian M. J. , Privat A. 
Published: April 2003

AbstractGM1 gangliosides were added to the medium of cultured raphe neurons enriched in the serotonergic phenotype in order to study their influence on biochemical and morphological growth parameters of serotonergic neurons. After 2 days of culture in the presence of GM1, specific uptake of serotonin measured by scintillation counting exhibited a moderate but significant increase for a GM1 concentration of 5 × 10−8M. Morphological parameters of 5‐HT neurons were measured after immunocytochemical staining with specific serotonin antiserum and digitalization of immunoreactive cells. Eight parameters were studied; for concentrations of 5 × 10−8 and 10−7M of GM1, the absolute neuritic field area and the total length of the segments were significantly increased, whereas the number of neuritic segments and their mean length were not modified. We conclude that GM1 ganglioside has a significant influence on the growth of serotonergic neurons. Moreover, electron microscopy showed, on treated cultures, a dramatic increase of the number of spicules all along the neuron's process, suggesting that GM1 could act by modifying the attachment of cells to their substrate. The possible molecular mechanisms of the action of GM1 are discussed.
Serotonin‐immunoreactive neurons in the brain of Manduca sexta during larval development and larval‐pupal metamorphosis
Authors: Granger Noelle A. , Homberg Uwe , Henderson Pamela , Towle Andrew , Lauder Jean M. 
Published: April 2003

AbstractThe developing serotonergic system of the tobacco hornworm, Manduca sexta, has been studied immunocytochemically in whole mount preparations of brain‐retrocerebral complexes. The distribution of serotonin‐immunoreactive cell bodies, fibers and terminal fields has been analysed during larval and larval‐pupal development using a specific rabbit antiserum against serotonin‐hemocyanin conjugates. The serotonergic system was conserved from the fourth to the fifth larval stadium, with minimal changes occurring until the onset of pupal development. At this time, alterations in the distribution of serotonin‐immunoreactive cells and processes were observed, including the apparent disappearance of some cell bodies and terminals. Nevertheless, the overall appearance of this system in the pupal brain was not significantly different from that in the larva. The larval pattern was characterized by eight bilateral groups of cell bodies which sent thick bridges of fibers across the midline, a feature strikingly similar to the serotonergic system in vertebrate embryos. In addition, three bilateral immunoreactive fields of arborization were observed around and ventral to these cell groups, together with regions of serotonin immunoreactivity in the medial and lateral protocerebral lobes. The central body, larval antennal centers, larval accessory lobes and the tritocerebrum were also immunoreactive. Fibrous networks of serotonergic processes were usually observed around nerves emanating from the brain, including the connectives from the brain to the corpus cardiacum and corpus allatum. Smaller varicosities were observed in the interior of these neurohemal and glandular organs and a network of 5‐HT fibers was occasionally found around the corpus cardiacum and corpus allatum. The possible relationship of serotonin to cerebral neuroendocrine functions during the postembryonic development of M. sexta is discussed.
Effects of acidic and basic fibroblast growth factors on proliferation and maturation of cultured rat oligodendrocytes
Authors: Besnard François , Perraud Frédéric , Sensenbrenner Monique , Labourdette Gérard 
Published: April 2003

AbstractA pure culture of oligodendrocytes has been developed starting from brain hemispheres of newborn rats. Various effects of acidic and basic fibroblast growth factors (FGFs) on the development of oligodendrocytes have been examined and compared. Both factors elicited similar effects, i.e. stimulation of the proliferation, inhibition of the specific activity of the marker enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase and decrease of the ratio of myelin basic protein positive cells. These results indicate that FGFs are very potent mitogens for oligodendrocytes, even in the absence of other cell types, but that they elicit a negative effect on the cell maturation, possibly related to their strong effect on proliferation.
Non‐specific cholinesterase activity of the developing peripheral nerves and its possible function in cells in intimate contact with growing axons of chick embryo
Authors: Dubovy Petr , Haninec Pavel 
Published: April 2003

AbstractThe results presented here demonstrate non‐specific cholinesterase (nChE) activity in the developing peripheral nerves of chick embryos at stages 25–26 according to Hamburger and Hamilton (1951, J. Morphol. 88, 49–92). Under the light microscope the use of simultaneous staining for nChE activity and silver proteinate impregnation revealed the axons to be surrounded by cells exhibiting nChE activity in the main nerve trunks and in the growing tips of nerves. Nerve branches arising from the main nerve trunks contained cells with positive reaction for nChE activity, too. Electron‐dense particles of the reaction product indicating nChE activity were found in the rough endoplasmic reticulum and in the perinuclear envelope of cells in close contact with growing nerve fibers and their growth cones. The same distribution of nChE activity was found in cells which were located near to nerve fasciculi but without direct contact with axons. Surprisingly, the cells in close contact with axons and their growth cones exhibited the end product of nChE activity in the outer part of their plasma membrane. The cells enveloping axons within the nerve trunks were apparently Schwann cells, while those around the growth cones at nerve tips could be identified as Schwann cells and/or mesenchymal cells of the hindlimb. The nChE reaction product was also detected in the axolemma of nerve fibers and their growth cones. The distribution of nChE activity in the developing peripheral nerves of chick embryos suggests that these molecules may influence the process of axonal elongation and locomotion. Several possible mechanisms of nChE action on growing axons can be presumed: (i) intracellular Ca2+ level regulation; (ii) providing an adhesive substrate; (iii) butyrate production affecting the cell metabolism and the distribution of neurotubules and neurofilaments. It is also assumed that nChE molecules are involved in the interactions of nerve fibers with Schwann cells and/or mesenchymal cells as well as in interneuronal interactions.
Factors affecting denervation‐like changes at the neuromuscular junction during aging
Authors: Rosenheimer Julie L. 
Published: April 2003

AbstractThe ability to sustain synaptic transmission diminishes with aging. To determine whether this is accompanied by alterations in the structure of the synapse, end‐plate architecture was examined in EDL muscles from 10‐ to 25‐month rats. There was a significant age‐related increase in end‐plate area and a decrease in the number of nerve terminals per end plate. Furthermore, the percentage of end plates with ultraterminal sprouts increased dramatically with age. To compare the morphological changes associated with aging to the changes in response to denervation, EDL muscles from 10‐ and 25‐month animals were partially denervated. Both end‐plate area and ultraterminal sprouting increased, while terminal number decreased following denervation in the 10‐month muscles. To determine whether the age‐ and denervation‐associated changes were accompanied by alterations in muscle‐derived nerve‐outgrowth factors, in vitro assays were performed. Neurite outgrowth was quantified from embryonic motoneurons incubated with muscle extract, or grown on cryostat‐cut muscle cross sections from 10‐ and 25‐month innervated and denervated EDL muscles. Both aged and denervated muscles induced greater degrees of neurite outgrowth compared with younger innervated muscles. Innervation to the EDL was then examined, and signs of axonal degeneration were observed. It is suggested that aging is associated with alterations in the motor axon to the EDL muscle. These changes are manifest at the neuromuscular junction. In turn, the muscle responds as if it were in a state of functional denervation.
Effects of MPTP on the cerebrovasculature
Authors: Adams James D. , Klaidman Lori K. , Odunze Ifeoma N. , Johannessen Jan N. 
Published: April 2003

AbstractThe neurotoxin, l‐methyl‐4‐phenyl‐l,2,3,6‐tetrahydropyridine, has been shown to cause pooling of blood in the brain microvasculature and decrease the permeability of the blood‐brain barrier. All areas of the brain examined in this study were affected. This study points out the possibility that reduced nutrient uptake, hypoxia and ensuing free radical damage are involved in the mechanism of toxicity of this neurotoxin.
NCAM as a differentiation marker of postmigratory immature neurons in the developing human nervous system
Authors: Terkelsen O.B.F. , Janas M. Stagaard , Bock E. , Møllgård K. 
Published: April 2003

AbstractThe regional distribution and cellular localization of the neural cell adhesion molecule were investigated in the developing nervous system of human embryos and fetuses, by using immunocytochemistry with antibodies against the human neural cell adhesion molecule. Embryos and fetuses with crown‐rump lengths ranging from 15 to 80 mm (corresponding approximately to 6–12 ovulation weeks) were examined. In the telencephalon, immunoreactivity was found in the primordial plexiform layer and in the early cortical plate. During later stages, immunoreactivity was present in the marginal zone, cortical plate, developing subplate zone and radiations of the internal capsule. In the mesencephalon and rhombencephalon, neuronal perikarya were outlined and strong staining was present in fiber bundles. In the spinal cord, strong immunostaining was present in fiber tracts and in dorsal and ventral roots. Immunostaining outlined perikarya of dorsal and ventral gray columns; the neuropil of the developing gray matter was also stained. Contrary to findings in some other species, precursor cells in the proliferating zones, i.e. all cells of ventricular zones and the external granular layer in the developing cerebellum, were not stained. Reactivity, however, was also observed in single mature‐looking nerve cell bodies and their processes, which were localized in proliferating zones. All peripheral nervous structures including nerve fibers and peripheral nervous tissue components derived from the neural crest (i.e. sensory and autonomic ganglia) expressed the neural cell adhesion molecule. At the cellular level staining always appeared to be associated with the entire cell membrane of a given neuron including its outgrowing processes. Immunocytochemical staining for neural cell adhesion molecule is an excellent method for the identification of single nerve fibers, nerves and nerve cell bodies in situ in the developing peripheral and early central nervous system. The neural cell adhesion molecule is suggested as a marker of postmigratory immature neurons in the developing human nervous system.
Expression in murine and human neuroblastoma cell lines of VGF, a tissue specific protein
Authors: Rossi Adelaide , Granata Filippo , Augusti‐Tocco Gabriella , Canu Nadia , Levi Andrea , Possenti Roberta 
Published: April 2003

AbstractScreening by different means has demonstrated the presence, in human and murine neuroblastoma cell lines, of VGF, a gene product identified in a limited number of neuronal and endocrine cells. Indirect immunofluorescence and Western and Northern blot analyses have shown the presence of this protein in some of the tested lines, confirming that VGF is not an ubiquitous molecule. Further studies, using human SK‐N‐BE and murine N18TG2 lines, showed that VGF expression is upregulated during differentiation, suggesting that various species, including man, express VGF and regulate it in a similar manner. The subcellular localization of the protein, which is associated with vesicles, its electrophoretic molecular profile and its specific release under different conditions are all consistent with results reported in other cells. Neuroblastomas are thus added to the class of VGF‐positive cells and provide a new in vitro model for investigation of the structural and functional properties of this protein.
Synaptic ribbons, spheres and intermediate structures in the developing rat retina
Authors: Hermes Birgit , Reuss Stefan , Vollrath Lutz 
Published: April 2003

AbstractThe present study was conducted to investigate the qualitative and quantitative development of synaptic bodies in retinae of Wistar rats during postnatal days 4–28. In addition, the effects of different light regimens and of eye pigmentation on SB numbers were studied. Synaptic bodies were counted and measured in the outer plexiform layer of retinal tissue fixed and processed by routine electron microscopical techniques.At postnatal days 4 and 5, retinae showed only few synaptic bodies. The main numerical development of synaptic bodies occurred between postnatal days 4 and 9, numbers remaining more or less constant thereafter. The intracellular location of synaptic ribbons changed from predominantly cytoplasmic sites to positions at the membrane. In Wistar rats of postnatal day 15 held under a light/dark regimen, synaptic ribbon numbers and lengths were found to be significantly larger at night than at daytime. This was not observed in animals kept under constant darkness. In retinae of a pigmented rat strain, Brown Norway, total numbers of synaptic bodies were similar to those of Wistar rats, whereas the relative proportions of synaptic ribbons and spheres or sphere‐like structures, respectively, differed between strains. These results are discussed with regard to synaptic body formation and regulation under the influence of light and eye pigmentation.
Transplantation of oligodendrocyte precursors in the adult demyelinated spinal cord: Migration and remyelination
Authors: Vignais L. , Oumesmar B. Nait , Mellouk F. , Gout O. , Labourdette G. , Baron‐Van Evercooren A. , Gumpel M. 
Published: April 2003

AbstractA demyelinating lesion induced by an injection of lysolecithin into the spinal cord can be partly repaired by oligodendrocyte precursors transplanted at a distance of 6–8 mm from the lesion. Using a non‐toxic fluorescent dye (Hoechst 33342) as a cell marker, we demonstrate that transplanted oligodendrocyte precursors from different origins (periventricular zone fragments from newborn mouse and cultured rat oligodendrocyte progenitor cells) can migrate along specific pathways (i.e. white matter fasciculi, ependymal wall, meninges and blood vessels). These cells can be attracted when passing at the vicinity of the lesion as well as differentiate and remyelinate axons with the lesion. Myelin repair thus appears to be the result of distinct successive events: migration, specific attraction, differentiation and myelination. This can occur in both shiverer and normal adult hosts.
Requirements for schwann cell migration within cns environments: A viewpoint
Authors: Franklin R.J.M. , Blakemore W.F. 
Published: April 2003

AbstractSchwann cells are able to migrate into the CNS and myelinate CNS axons in a number of developmental and pathological situations. Morphological studies based on normal, mutant and experimentally‐lesioned tissue have indicated that Schwann cells are only able to enter the CNS when the integrity of the astrocytic glia limitans is disrupted. The significance and subtlety of the interactions between Schwann cells and astrocytes have been further explored by glial cell transplantation studies. These studies support in vitro observations on Schwann cell behaviour in highlighting the importance of extracellular matrix for both migration and myelin sheath formation. The failure of Schwann cells to intermix with astrocytes is an important aspect of glial cell biology which will have a bearing on efforts to remyelinate demyelinated axons by Schwann cell‐transplantation.
High gelsolin content of developing oligodendrocytes
Authors: Léna J.Y. , Legrand Ch. , Faivre‐Sarrailh C. , Sarliéve L.L. , Ferraz C. , Rabié A. 
Published: April 2003

AbstractThe actin‐binding protein gelsolin that severs and caps the actin microfilaments under the control of the cytoplasmic free calcium and the membranous phosphatidylinositol 4,5‐bisphosphate, is essentially restricted to the oligodendroglia in the central nervous system. Immunocytochemistry showed that gelsolin is an early marker of oligodendrocytes, both in vivo, in the rat cerebellum, and in vitro, in oligodendrocyte culture. We report the early appearance of gelsolin in A2B5‐positive precursor oligodendrocyte cells and the specific expression of gelsolin in OL‐1‐, GC‐, and MBP‐positive oligodendrocytes in culture. The protein was distributed throughout the cell body and in the branched cell processes of cultured oligodendrocytes, but not in the MBP‐positive membrane sheets. Gelsolin is thus cytosolic and not a myelin component. The quantitative study demonstrated that the cerebellar gelsolin content changes significantly with age, with the maximal value at the age of 21 days, confirming that large amounts of gelsolin are transiently synthesized during development, especially from the first events of myelinogenesis. The results are consistent with gelsolin being involved, through its effects on the actin cytoskeleton, in the motile events occurring during the growth of the oligodendroglial processes towards the axons and the wrapping of the myelin sheaths around the axons.
GDF‐5 deficiency in mice delays Achilles tendon healing
Authors: Chhabra A. , Tsou D. , Clark R. T. , Gaschen V. , Hunziker E. B. , Mikic B. 
Published: April 2003

AbstractThe aim of this study was to examine the role of one of the growth/differentiation factors, GDF‐5, in the process of tendon healing. Specifically, we tested the hypothesis that GDF‐5 deficiency in mice would result in delayed Achilles tendon repair. Using histologic, biochemical, and ultrastructural analyses, we demonstrate that Achilles tendons from 8‐week‐old male GDF‐5 –/– mice exhibit a short‐term delay of 1–2 weeks in the healing process compared to phenotypically normal control littermates. Mutant animals took longer to achieve peak cell density, glycosaminoglycan content, and collagen content in the repair tissue, and the time course of changes in collagen fibril size was also delayed. Revascularization was delayed in the mutant mice by 1 week. GDF‐5 deficient Achilles tendons also contained significantly more fat within the repair tissue at all time points examined, and was significantly weaker than control tissue at 5 weeks after surgery, but strength differences were no longer detectable by 12‐weeks. Together, these data support the hypothesis that GDF‐5 may play an important role in modulating tendon repair, and are consistent with previously posited roles for GDF‐5 in cell recruitment, migration/adhesion, differentiation, proliferation, and angiogenesis. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.