bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rescue of basal forebrain cholinergic neurons after implantation of genetically modified cells producing recombinant NGF
Authors: Strömberg I. , Wetmore C. J. , Ebendal T. , Ernfors P. , Persson H. , Olson L. 
Published: January 2005

AbstractMouse 3T3 fibroblasts were genetically modified by transfection with a mammalian expression vector containing the rat β‐nerve growth factor (NGF) gene. The transfected cell line, designated 3E, contains several hundred copies of the rat NGF gene and secretes high levels of biologically active NGF. Pieces of collagen gel containing the NGF‐secreting 3E cells were grafted to the brains of unilaterally fimbria‐fornixlesioned rats. Grafts of the genetically modified NGF‐producing cells rescued axotomized basal forebrain cholinergic neurons and significantly reduced cholinergic cell death in the medial septum as copared with rats treated with grafts of the parental 3T3 cells. Grafted fibroblast cells were detected, and rescue effects were noted up to 6 weeks after grafting. Local effects of NGF secreted by grafted cells were also seen at the gel‐brain border in the form of sprouting acetylcholinesterase immunoreactive host cortical fibers. We suggest that implantation of genetically modified cells producing NGF may have therapeutic applications in rescuing damaged central cholinergic neurons in senile dementia of the Alzheimer type as well as in providing trophic support for chromaffin tissue grafts in Parkinson's disease.
Role of the cAMP‐dependent protein kinase and protein kinase C in regulating the morphological differentiation of PC12 cells
Authors: Glowacka D. , Wagner J. A. 
Published: January 2005

AbstractThe cell line A126‐1B2 is a PC12‐derived mutant that is resistance to the toxic effects of dibutyryladenosine 3′:5′‐cyclic monophosphate (dbcAMP) and is deficient in adenosine 3′:5′‐cyclic monophosphate (cAMP)‐dependent protein kinase II (PKAII). This mutant formed neurites in response to nerve growth factor (NGF), but not in response to dbcAMP; and dbcAMP did not increase the rate of NGF‐dependent neurite formation. Thus, while PKAII is essential for process formation in response to agentsw that act through the cAMP‐dependent pathway, activation of PKAII is not essential for NGF‐dependent neurite formation. Unexpectedaly, NGF and phorbol 12‐myristate 13‐acetate (PMA; 10–1,000 nm) synergistically stimulated the formation of shortprocesses that were apparent within 30 min of NGF addition in 85% of these mutant dells. These processes were similar, but not identical, in appearance to the NGF‐dependent neurites that formed only after a period of 24–48 hr. This effect is dependent on the activation of protein kinase C (PKC) because an inactive phorbol ester was without effect. In contrast, therewas only a small effect of NGF and/or PMA on process formation in wiod type cells within the first few hours. The effect of PMA is not augmented by dbcAMP in the A126‐1B2 mutant cells. After several hours, PMA caused a concentration‐dependent decrease in cell adhesion; and higher concetrations of PMA resulted in a transient detachment of the cells and a loss of neurites. These experiments suggest a role for PKC in the regulation of process formation.
Myelin basic protein: Interaction with calmodulin and gangliosides
Authors: Chan K.‐F. J. , Robb N. D. , Chen W. H. 
Published: January 2005

AbstractThe structural characteristics of myelin basic protein (MBP) involved in protein‐protein and protein‐lipid interactions were investigated. Rabbit MBP could bind calmodulin (CaM) in the presence of Ca2+ to form a complex that remained undissociated in 8 M urea. However, no tight complex formation was observed when the divalent cation was absent. These results suggest that MBP may contain a hydrophobic domain similar to those in the other well‐characterized CaM‐binding proteins. The stoichiometry of calmodulin binding to MBP was approximately 1:1. Prior limited proteolysis of MBP with trypsin abolished the formation of the MBP‐CaM complex, indicating that the entire MBP polypeptide may be involved in the recognition of the hydrophobic clefts in CaM. MBP also formed tight complexes with gangliosides, but the presence of Ca2+ was not‐required. Binding of gangliosides to MBP‐CaM complex released CaM from the complex. The ganglioside‐binding sites in MBP were determined after trisecting the protein at two glutamic acid residues with Staphylococcus aureus V8 protease. Subsequent binding studies revealed that a 9.5‐kDa polypeptide, which may correspond to the NH2‐terminal domain (residues 1‐83) of MBP, had higher affinity for the binding of lucifer yellow CH‐labeled GM1 than did the other two polypeptides, of apparent molecular mass (Mr) 5,500 and 4,500, respectively. Among the various proteins in purified guinea pig brain myelin, synaptosomes, and synaptosomal membrances, MBP was found to have the highest affinity in binding lucifer yellow CH‐GM1.
Treatment with forskolin for 8 hours during the day increases melatonin synthesis in the Syrian hamster pineal gland in organ culture: The long lag period is required for RNA synthesis
Authors: Santana C. , Menendez‐Pelaez A. , Reiter R. J. , Guerrero J. M. 
Published: January 2005

AbstractThe exposure of organ‐cultured pineal glands of Syrian hamsters to forskolin, an adenylate cyclase activator, caused marked increases in melatonin levels when glands were collected at the second half of the dark period and incubated for 4 h. However, when glands were collected at the beginning of the dark period and incubated with the same drug, a significant increase in melatonin content was observed only after 6–8 h. Likewise, when glnds were collected at the beginning of the light period, forskolin stimulated melatonin synthesis only after 6–8 h of incubation with the drug. These results support the existence of a relatively long lag period necessary for the induction of melatonin production in the Syrian hamster pineal gland. Experiments with actinomycin D indicate that RNA synthesis occurs during the lag period; thus, actinomycin D blocks the induction of melatonin synthesis by forskolin in glands collected at the beginning of the dark period and incubated for 8 h. In contrast, when pineal glands were collected from hamsters killed in the second half of the dark period, and incubated with forskolin for either 4 or 8 h, actinomycin D was unable to block the induction of melatonin production. These data suggest that RNA, presumably messenger RNA, which is necessary for increasing hamster pineal melatonin synthesis, is synthesized and accumulates during the first half of the night.
Expression of the oligodendrocyte marker 2′3′‐cyclic nucleotide 3′‐phosphodiesterase in non‐glial cells
Authors: Staugaitis S M , Bernier L. , Smith P R , Colman D. R. 
Published: January 2005

AbstractThe 46 kD isoform of the 2′3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPi) was expressed in HeLa cells by transfection of its cDNA clone. The distribution of this polypeptide as mapped by indirect immunofluorescence and conventional epifluorescence microscopy appeared diffuse and generally uniform throughout the cytoplasm. Confocal microscopic imaging and analysis of pseudocolores images confirnes this distribution but also revealed that there was a high concentration of CNPi meat the plasma membrane of the cell. This pattern is very similar to that observed by immunoelectronmicroscopy of myelinating oligodendrocytes (Trapp et al.: J Neurochem 51:859–868. 1988: Braum et al.: J Neurosci 8:3057–3066, 1988). These results suggest that CNP may interact with a membrane‐associated molecule that is not unique to oligofendrocytes.
Bundling and cross‐linking of intermediate. Filaments of the nervous system
Authors: Shaw G. , Hou Zhao‐Chen 
Published: January 2005

AbstractUltrastructural studies have shown that neurons and glia in the mammalian nervous system contain bundles of often hundreds or more individual intermediate filaments. The means by which these bundles are formed and maintained has not been examined. We describe a series of simple experiments indicating that intermediate filament bundles derived from neuronal and glial processes are extremely stable, being resistant to a variety of extreme conditions. Furthermore, a preliminary examination of the mechanism of bundling for both types of filaments rules out several models for the production and control of crosslinking. We conclude that the long processes of both neurons and glia are stabilized by bundled intermediate filaments exhibiting strong interfilament interactions. We present a reconcilication these findings with previous data suggesting that neurofilaments are not actively cross‐linked. We also describe a novel detergent‐insoluble annular cytoskeletal structure, which appears to constrict bundles of axonal neuro filaments locally.
Tyrosine hydroxylase gene expression in human ventral mesencephalon: Detection of tyrosine hydroxylase messenger RNA in neurites
Authors: Dumas S. , Javoy‐Agid F. , Hirsch E. , Agid Y. , Mallet J. 
Published: January 2005

AbstractThe distribution of both tyrosine hydroxylase (TH) antigen and messenger RNA was investigated in the ventral mesencephalon from human brain using a 35S‐labeled human TH cDNA probe and a polyclonal TH antibody. A hybridization signal was detected not only in the perikaryon but also in the neurites, most probably dendrites, of immunoreactive neurons. In cell bodies, the level of TH mRNA varies, revealing a regional heterogeneity. In the substantia nigra of patients with Parkinson's disease the number of labeled cells was markedly reduced as compared to controls.
Transferrin gene expression and secretion by rat brain cells in vitro
Authors: De los Monteros A. Espinosa , Kumar S. , Scully S. , Cole R. , de Vellis J. 
Published: January 2005

AbstractWe have previously shown by immunocytochemistry in rat primary glial cultures that transferrin (TF) is an early developmental marker for oligodendrocytes. The present work addresses the issue of Tf gene expression and synthesis by neural cells in vitro. For this purpose, we used rat embryonic neuronal cultures and newborn glial cultures of astrocytes and oligodendrocytes. Cultured fibroblasts and C6 glioma cells were used as negative controls. We found that Tf mRNA is present in oligodendrocytes, astrocytes, and neurons. However, oligodendrocytes and astrocytes, but not neurons, were shown to synthesize and secrete Tf. Neither fibroblasts nor C6 glioma cells expressed detectable amounts of Tf mRNA. Levels in astrocyte cultures appeared to be under hormonal control since hydrocortisone markedly reduced message levels. These results show that both astrocytes and oligodendrocytes can synthesize and secrete Tf under cell culture conditions. However, epigenetic factors, such as hydrocortisone, may repress the expression of Tf in astrocytes in vivo.
The relationship of expression of statin, the nuclear protein of nonproliferating cells, to the differentiation and cell cycle of astroglia in cultures and in situ
Authors: Fedoroff S. , Ahmed I. , Wang E. 
Published: January 2005

AbstractCells in the quiescent, nonproliferative state express a protein, statin, in their nuclei. When the cells re‐enter the cell cycle, statin disappears and another protein, cyclin, appears. We have examined mouse astroglia at various stages of differentiation in cultures and astroglia in adult mouse brains for the presence of statin. In cultures initiated from the neopallium of newborn mice, the glial fibrillary acidic protein (GFAP)+ stellate astrocytes were statin‐negative (statin−) but cyclin‐positive (cyclin+).In the same cultures, large flat cells (senescent cells) were statin+ but cyclin−. In frozen sections of the brains of adult mice and in brain smears, GFAP+ astrocytes were statin−. Neither stellate astrocytes grown in cultures for 30 or more days nor astrocytes in adult mouse brain were labeled when pulsed with bromodeoxyuridine (BudR). When astroglia were treated with dibutyryl cyclic adenosine monophosphate(dBcAMP), Large stellate cells that closely resemble reactive astrocytes in situ formed. These cells were all statin+ from 11–62 days in vitro; however, reactive astrocytes in mouse neopallium, 4–50 days after a stab wound, were statin−. In colony cultures, senescent cells became statin+, whereas stellate astrocytes and their precursor cells remained statin−. These observations indicate that normal astrocytes both in cultures and in situ retain the potential to divide and probably progress through the cell cycle at a very slow rate.
Low‐energy laser irradiation—a new measure for suppression of arachidonic acid metabolism in the optic nerve
Authors: Naveh N. , Bar‐Ilan A. , Rosner M. , Schwartz M. , Weissman C. , Belkin M. 
Published: January 2005

AbstractHelium‐neon lowenergy laser (LEL) irradiation, known for its therapeutic effects in arthritis, wound healing, and muscular strain, was applied to eyes of rats that had sustained and optic nerve crush injury. Crush injury to the optic nerve resulted in a longlasting in vitro elevation of prostaglandin E2(PGE2) production (1.8‐3.9‐fold above control values during the 12 day study period). LEL irradiation per se had no effect in vitro on PGE2 production by the optic nerve; however, LEL irradiation of eyes with crushed optic nerve inhibited the enhanced production of PGE2 and leukotriene B4 in vitro by 55% and 75% during the late and immediate phase after trauma, respectively. Our findings of the suppressive effect of LEL irradiation on arachidonic acid metabolism are reminiscent of the actions of steroidal and nonsteroidal anti‐inflammatory drugs, and might indicate, for the first time, the possible biochemical mechanisms associated with the clinical anti‐inflammatory effects of LEL irradiation.
GD3 ganglioside is prevalent in fully differentiated neurons from rat retina
Authors: Daniotti J. L. , Landa C. A. , Gravotta D. , Maccioni H. J. F. 
Published: January 2005

AbstractAdult mammalian retinas contain unusually high amounts of GD3, a ganglioside of the lactosylceramide series. In this respect, they differ from adult avian retina and other regions of the adult avian and mammalian brain, where GD3 is a minor ganglioside and gangliosides of the gangliotetraosylceramide series (GM1, GD1a, GD1b, GT1b) are the predominant ones. We compare here the ganglioside patterns of rat, human, horse, and guinea pig retinas, which are known to differ in the degree of vascularization and astrocytic cell content. All these retinas showed a prevalence of pathway “b” gangliosides over pathway “a” gangliosides but showed no correlation between GD3 content and the degree of vascularization and astrocytic cell content. Immunostaining of rat retina sections showed the presence of GD3 in the inner and outer plexiform layers and also in the ganglion cell and inner nuclear layers. About 60% of the cells dissociated from rat retina showed immuno‐co‐localization of GD3 and the neuronal marker class III β tubulin isotype or cholera toxin binding. All morphologically identifiable glial Muller cells coexpress GD3 and gangliotetraosylgangliosides. GD3 was a minor ganglioside among these axonally transported by ganglion cells in rats and guinea pigs, suggesting that it is either not synthesized by ganglion cells or, if so, it is restricted to the cell soma and/or dendritic tree.Our results demonstrate that, unlike neurons from avian retina and other regions of avian and mammalian brain, neurons from mammalian retina not only contain gangliosides of the gangliotetraosylceramide series but also keep a prevalence of gangliosides of the lactosylceramide series (GD3) when they are fully differentiated.
Involvement of dihydropyridine‐sensitive calcium channels in nerve growth factor‐dependent neurite outgrowth by sympathetic neurons
Authors: Rogers M. , Hendry I. 
Published: January 2005

AbstractWe have used a number of pharmacological manipulations of calcium influx to alteeer the nerve growth factor (NGF)‐elicited neurite outgrowth response of SCG neurons. Our results indecate that influx of extracellular calcium is critical to sympathetic SCG neurite outgrowth. Effective blockade of this process was produced by the inorganic calcium channel blockers Cd2+ (with an IC50 of 48μM), Co2+ (129μM), and Ni2+ (180 μM). More specifically, there is a significant contribution from dihydropyridine‐sensitive L‐type calcium channels to NGF‐activated neurite outgrowth, as evidenced by the significant inhibition of neurite outgrowth by diltiazem (IC50 of 17μM) and nifedipine (3μM). Further, increases in calcium influx can elicit an enhanced neurite outgrowth response, as shown by the calcium channel agonist Bay K 8644 wich potentiated neurite outgrowth by up to 40%.
Tellurium‐induced neuropathy: A model for reversible reductions in myelin protein gene expression
Authors: Toews A. D. , Lee S. Y. , Popko B. , Morell P. 
Published: January 2005

AbstractInclusion of 1.1% tellurium in the diet of developing rats causes a highly synchronous primary demyelination of peripheral nerves, which is followed closely by a period of rapid remyelination. The demyelination is related to the inhibition of squalene epoxidase activity, which results in a block in cholesterol synthesis and accumulation of squalene. We now report that the demyelination resulting from this limiting of the supply of an intrinsic component of myelin (cholesterol) leads to repression of the expression of mRNA for myelin‐specific proteins. Tellurium exposure resulted in an increase in total RNA (largely rRNA) in sciatic nerve, which could not be accounted for by cellular proliferation; these increased levels of rRNA may be a reactive response of Schwann cells to toxic insult and may relate to the higher levels of protein synthesis required during remyelination. In contrast, steadystate levels of mRNA, determined by Northern blot analysis, for Po and myelin basic protein were markedly decreased (levels after 5 days of tellurium exposure were only 10‐15% of control levels as a fraction of total RNA and 25‐35% of control levels when the increased levels of total RNA were taken into account). Message levels increased during the subsequent period of remylination and reached near‐normal levels 30 days after beginning tellurium exposure. Although message levels for the myelin‐associated glycoprotein showed a similar temporal pattern, levels did not decrease as greatly and subsequently increased sooner than did levels for Po and myelin basic protein. The coordinate alterations in message levels for myelin proteins indicate that Schwann cells can down‐regulate and then up‐regulate the synthesis of myelin in response to alterations in the supply of membrane components.
Iron‐enriched oligodendrocytes: A reexamination of their spatial distribution
Authors: LeVine S. M. , Macklin W. B. 
Published: January 2005

AbstractPrevious histochemical studies of iron in the brain demonstrated iron enrichment in oligodendrocytes, but the iron‐enriched oligodendrocytes had a spatially restricted distribution that excluded major white matter tracts. In this study we used techniques designed to permeabilize tissue, combined with iron histochemistry, and we observed iron‐enriched oligodendrocytes in regions previously thought to lack such cells. Our data suggest that most, if not all, oligodendrocytes are enriched in iron. We suggest that iron functions in the formation and/or maintenance of the myelin sheet and may play a role in the pathology of myelin diseases.
Lurcher purkinje cells express glutamic acid decarboxylase and calbindin mRNAs
Authors: Wuenschell C. W. , Messer A. , Tobin A. J. 
Published: January 2005

AbstractPurkinje neurons in immature Lurcher (Lc/ +) mice are destined to die as a result of a defect intrinsic to the dying cells. We have used in situ hybridization to determine whether the Lc allele interferes with the normal program of gene expression in the doomed Purkinje cells. In P21 mice, degeneration of Purkinje cells is well underway, but the surviving Purkinje cells continue to express the mRNAs for both glutamate decarboxylase and calbindin D28k, two proteins whose expression is characteristic of normal Purkinje neurons. We conclude that the Lc allele probably does not interfere with the developmental program but acts to cause cell death in already differentiated Purkinje neurons.
Properties of acetylcholinesterase in axolemma‐enriched fractions isolated from bovine splenic nerve
Authors: Hannesson H. H. , DeVries G. H. 
Published: January 2005

AbstractThe properties of acetylcholinesterase (AChE) in axolemma‐enriched fractions (AEF) from bovine splenic nerve were investigated to see if they differed in any way from those of the AChE in diaphragm muscle. The axolemmal enzyme had a low Km for acetylthiocholine (ca. 90 μM), exhibited substrate inhibition, and had a well‐defined optimum of substrate concentration of 1mM. The rate of hydrolysis of substrate decreased with increasing acyl chain length (acetyl‐>propionyl‐>butyryl‐). The AChE inhibitors eserine and hexamethonium were competitive inhibitors of the membrane‐bound enzyme, whereas lidocaine was a noncompetitive inhibitor; these results were comparable to the effect of these inhibitors on diaphragm muscle AChE. The axolemmal enzyme was more efficiently solubilized and more stable in nonionic detergents such as Triton X‐100 and Tween 20 than charged detergents such as lysolecithin and zwitterionic detergents. These results indicate that the AChE present in bovine splenic nerve AEF is identical to the previously characterized AChE from other sources.
Differential effect of μ, δ, and κ ligands on G protein α subunits in cultured brain cells
Authors: Vogel Zvi , Barg J. , Attali B. , Simantov R. 
Published: January 2005

AbstractRat and guinea pig fetal brain cell cultures and immunoblotting techniques were used to study the effect of receptor selective opioids on the level of the membrane‐bound α1 and α0 GTP binding protein subunits. Incubation of rat hindbrain cultures with the μ selective peptide DAGO decreased the amount of both α proteins. The reduction observed was equivalent to 36% in α0 and 41% in α1. On the other hand, incubation of rat forebrain cultures with this peptide had an opposite effect, increasing the α0 and α1 levels by 66% and 68%, respectively. This differential effect of the peptide on the G proteins at the two brain areas may reflect the selective interaction at the receptor level; DAGO induced a fast and effective receptor down‐regulation (50% decrease in Bmax) in hindbrain but not in forebrain cultures. Moreover, δ and μ selective ligands differed in their effect, as indicated by the finding that the δ selective peptide DPDPE increased the amount of both α proteins in hindbrain cultures by 40%. Similar experiments conducted with guinea pig brain aggregate cultures indicated that the κ selective agonist U50, 488 decreased the amount of the membrane bound α1 protein subunit by 56%. The results thus indicate that opioid agonists, interacting selectively with the three types of opioid receptors, induce a complex repertoire of changes in the immunoreactive levels of the membrane‐bound α GTP binding protein subunits in various CNS structures.