bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of thyroxine on transmembrane resting potentials of skeletal muscle cells in culture
Authors: Sampson S. R. , Bannett Rena R. , Shainberg A. 
Published: January 2005

AbstractThe effect of thyroxine (T4) was studied on the transmembrane resting potential (Em) of rat skeletal muscle cells in culture. In agreement with previous studies, we found the Em of developing muscle cells to increase with age from Day 3 to Day 7 or 8, at which time a plateau is reached. The values of Em we obtained (−65 to −75 mV) were 15–20 mV higher than those (−50 to −55 mV) reported by others. Treatment of mature myotubes with T4 resulted in a significant increase in resting Em. There was only a slight difference between T4‐treated and control cells with regard to the relation between extracellular K+ concentration and resting Em. Within 20–30 min of exposure to ouabain (10−4–10−3M) resting Em of both T4‐treated and control cells had fallen to about the same value. This effect was reversible. Thus, T4 stimulates the activity of an electrogenic Na/K‐ATPase in the membrane of cultured skeletal muscle cells.
Comparison of centrifugation and filtration assays of ligand binding: Do multiple GABA receptive sites exist?
Authors: Patel Shutish C. , Peck Ernest J. 
Published: January 2005

AbstractFiltration and microcentrifugation procedures for the separation of bound and free ligand are compared for the assay of GABA receptors. The 3H‐GABA and 3H‐muscimol are employed as ligands in saturation analyses of SPM and JC preparations. A direct comparison of the two methods, applied to two membrane preparations and two ligands, reveals that nonspecific binding is consistently higher with the microcentrifugation procedure. Analysis of the binding data yields essentially the same constants in either case; however, the filtration assay provides a better estimate in all cases.
The effect of transmitter antagonists on phasic respiratory neurons
Authors: Wang L. , Boyarsky L. L. , Frazier D. T. 
Published: January 2005

AbstractThe activity of inspiratory neurons in the nucleus tractus solitarius (NTS) and of expiratory neurons in the nucleus retroambigualis (NRA) was recorded during the iontophoresis of L‐glutamate, bicuculline, and strychnine in chloralose‐urethane‐anesthetized cat. Bicuculline methoxide caused increased activity of NTS and NRA neurons during their active or burst phases. Neither bicuculline nor strychnine caused increased activity during the silent phases of NTS or NRA neurons. When neurons were driven to fire during their silent phase by L‐glutamate, the application of bicuculline methoxide caused a diminution of the evoked activity. It is concluded that both inspiratory and expiratory neurons receive inhibitory inputs during both their active and silent phases. Gamma‐aminobutyric acid appears to be gating both the excitatory and inhibitory information to NTS and NRA neurons. Strychnine was generally ineffective in changing the firing patterns of inspiratory and expiratory neurons suggesting a limited role of glycine, taurine, and L‐alanine in the respiratory network.
Metabolic fate of [14C]‐glutamine in mouse cerebral neurons in primary cultures
Authors: Yu A. C. H. , Fisher T. E. , Hertz E. , Tildon J. T. , Schousboe A. , Hertz L. 
Published: January 2005

AbstractThe metabolic fate of L‐[14C]‐glutamine was followed in cerebral cortical neurons in primary cultures, a GABAergic preparation. Part of the glutamine was converted to GABA (0.3 nmol/min per mg protein), which is consistent with the presence of glutaminase and glutamate decarboxylase activity in the cells and with findings by other authors in vivo or in brain slices. However, an even larger part (1.8 nmol/min per mg protein) was converted to CO2 and succinate via an oxidative deamination to α‐ketoglutarate. This is not consistent with the concept that transfer of glutamine from astrocytes to neurons should replenish neuronal GABA stores quantitatively after release of GABA and its partial accumulation into astrocytes, but it is well compatible with the recent demonstration of a net glutamine uptake by the brain.
Glycoproteins and proteins in an axolemma‐enriched fraction and myelin from developing rats: Effect of maternal ethanol consumption
Authors: Gnaedinger J. M. , Druse M. J. 
Published: January 2005

AbstractThe present study examined proteins and glycoproteins from an axolemma‐enriched fraction from the developing offspring of female rats that were pair‐fed control or 6.6% (50 g/liter) ethanol liquid diets on a chronic basis prior to parturition. In addition, this study examined the synthesis of the major CNS myelin‐associated glycoprotein (MAG) as an index of myelin maturation. The results of the latter study demonstrated normal MAG maturation in ethanol‐treated rats. However, a significant decrease in the proportion of radioactivity associated with MAG was found in the developing offspring of ethanol‐treated rats.The major axolemmal proteins from 32‐day rats included those with molecular weights of 105 K, 81 K, 62 K, 55 K, 52 K, 36 K, and 33 K. Major peaks of radioactivity were associated with fucosylated axolemmal glycoproteins with apparent molecular weights of 150 K, 130 K, 85 K, 76 K, and 64 K. Several development‐related changes in the protein composition of axolemma‐enriched fractions were observed in control animals. Between 22 and 32 days of age control rats exhibited a significant (P <.05) decrease in the proportion of axolemmal proteins that had apparent molecular weights of 150 K, 105 K, and 62 K. A development‐related decrease in the 105 K axolemma‐associated protein did not occur during the 22–32‐day age period in the offspring of ethanol‐treated animals. At 22 days the proportion of this 105 K protein in affected offspring was significantly (P <.05) less than that in age‐matched control rats and comparable to that in 32‐day control rats. The relative distribution of radioactivity among fucosylated axolemmal glycoproteins also changed significantly between 22 and 32 days of age. These changes include a decrease in the proportion of radioactivity associated with the 110 K, 55 K, and 52 K fucosylated glycoproteins and an increase in the proportion of radioactivity associated with the 85 K and 67 K glycoproteins. Several small, but significant (P <.05) alterations were found associated with glycoproteins in an axolemma‐enriched fraction from 22‐ and 32‐day ethanoltreated rats.
Ultrastructural organization of posterior and anterior barrels in the somatosensory cortex of rat
Authors: Patel‐Vaidya U. 
Published: January 2005

AbstractThe somatosensory barrels in layer IV of rat cerebral cortex were studied on uniformly oriented, serial, tangential sections by a combination of light microscope and ultrastructural techniques. Section orientation between sections was maintained by blood vessel patterns. The principal elements of both anterior and posterior barrels were quantified and analyzed in relation to proportional content and nonrandom spatial arrangement over depth in layer IV. Elements studied in this manner included neurons, myelinated axons, apical dendrites, synapses, glial cells, and blood vessels. In general, constituents were found to be arranged in a highly ordered fashion similar to other discretely organized sensory cortical areas. Myelinated axons outlined the basic structure of the barrels with the osmium stainig employed. Neurons appeared organized in small clusters. In addition apical dendrites, synapses, and blood vessels also exhibited nonrandom distribution complementary to the organization of axons and neurons. Anterior and posterior barrels differed slightly in their organization of elements.
Neuroimmunology of gangliosides in human neurons and glial cells in culture
Authors: Kim S. U. , Moretto G. , Lee V. , Yu R. K. 
Published: January 2005

AbstractGangliosides (sialic‐acid‐bearing glycolipids) have received attention in recent years because of their role in cell recognition phenomena, synaptic transmission, memory generation, and nerve regeneration in the fields of neurosciences. It is suggested that each brain region or each neural cell type may contain a specific and characteristic set of gangliosides.We have investigated the immunocytochemical localization of several classes of gangliosides that include GM1, GM4, GD3, and GQ gangliosides on the cell surface of various cell types found in human neural cell cultures with antibodies specific for these gangliosides. Cell cultures were obtained from adult human brains and fetal human dorsal root ganglia and spinal cord and cultured in vitro for the period up to 6 months and utilized for the ganglioside immunocytochemistry.It was demonstrated that (1) GM1 ganglioside was present in all galactocerebroside‐positive oligodendrocytes and most of glial fibrillary acid protein (GFAP)‐positive astrocytes (80%), most of neurofilament‐positive neurons (80%), 50–70% of Schwann cells, and 5–10% of fibronectin‐positive fibroblasts; (2) GM4 ganglioside could be detected in all oligodendrocytes, 80% of astrocytes, and 50% of Schwann cells, while no staining was found in neurons or fibroblasts; (3) GD3 ganglioside was present in all oligodendrocytes and 5–10% of astrocytes but not in neurons, Schwann cells, or fibroblasts; and (4) all of fetal CNS neurons and approximately 80–90% of fetal dorsal root ganglia (DRG) neurons and a small percentage of astrocytes (10–20% in fetal and <1% in adult astrocytes) was labeled by A2B5 antibody which is specific for GQ ganglioside, while this antibody did not stain cell surface of oligodendrocytes, Schwann cells, or fibroblasts.Three classes of gangliosides, GM1, GM4, and GD3 were found to be definite components of fetal and adult human oligodendroglial plasma membrane, while GM1 and GM4 gangliosides were detected on the surface of most astrocytes. Only a minor population of astrocytes from both fetal and adult human CNS contained GD3 and GQ gangliosides. Two classes of gangliosides, GM1 and GQ, were detected on the surface of fetal human neurons. More than half of fetal Schwann cells reacted to GM1 and GM4 antibodies but did not to GD3 or GQ antibodies. We recognized the presence of a specific and characteristic set of gangliosides on the cell surface of different human neural cell types and these findings should facilitate further investigation of the precise biological activity of these gangliosides.
Astrocyte culture on nitrocellulose membranes and plastic: Detection of cytoskeletal proteins and mRNAs by immunocytochemistry and in situ hybridization
Authors: Eng L.F. , Stöcklin E. , Lee Y.‐L. , Shiurba R.A. , Coria F. , Halks‐Miller M. , Mozsgai C. , Fukayama G. , Gibbs M. 
Published: January 2005

AbstractNeonatal rat brain astrocyte secondary cultures were established on nitrocellulose membrane filters (13‐mm diameter MilliporeTM disk) and on plastic coverslips in serum‐supplemented medium. On these substrata, cultured astrocytes changed their shape from flat and polygonal to stellate in the absence of hormones or growth factor supplements. Cultures became confluent after 4 days, and astrocytes on nitrocellulose filters continued to differentiate morphologically and biochemically, as evidenced by extensive cytoplasmic process formation and glial fibrillary acid protein (GFAP) accumulation. Cultures were immunostained for GFAP and vimentin. mRNAs to GFAP, vimentin, alpha and beta tubulin, and actin also were detected by in situ hybridization with biotinylated cDNA probes. The astrocyte culture method on nitrocellulose provides a simple, versatile means of comparing undifferentiated, morphologically mature, reactive, and neoplastic astrocytes in vitro.
Biological activity of region 65–102 of the myelin basic protein
Authors: Hashim G.A. , Day E.D. , Fredane L. , Intintola P. , Carvalho E. 
Published: January 2005

AbstractRegion 65‐102 of the myelin basic protein (MBP) houses a number of antigenic determinants known to induce delayed‐type hypersensitivity, experimental allergic encephalomyelitis (EAE), suppressor cell function, and antibodies. In this report we describe the biological activity of synthetic peptides S53, S55, and S49 with sequence homology to region 69‐84 of the rat, guinea pig, and bovine MBP, Peptide S53‐A, defined by residues 75‐84 of the guinea pig (SQRSQDEN) and of the rat (SQRTQDEN) MBP induced clinical signs of disease in Lewis rats. These included weight loss, flaccid tail, “muscle wasting” and hind‐leg weakness. Histological examination of brain, spinal cord, and sciatic nerve sections of diseased rats revealed the complete absence of focal and perivascular lymphocytic infiltrates characteristic of demyelinating EAE lesions. Elongation of peptide S53 by three or six residues to residue sequences naturally found at its N‐terminal end gave rise to peptides S55S (PQKSQRSQDEN) and S49S (GSLPQKSQRSDQDEN), respectively. Lewis rats challenged with either S55S or S49S developed classical clinical and histological signs of EAE. Severe hindleg paralysis was accompanied by incontinence and sometimes death. Injected in the form of carrier‐free peptide, S53 was a meager B cell immunogen. S53 conjugated with methylated‐bovine serum albumin was also a potent immunogen and produced clinical signs of disease without CNS pathology. By comparison, carrier‐free S55S and S49S were potent immunogens giving rise to antibodies that cross reacted completely and competitively with S55S but considerably less so with S53. The results show that the sequence of S53 defines an epitope responsible for the formation of anti‐S53 antibodies. Elongation of the S53 sequence at its N‐terminal end generated an additional epitope which induced cell‐mediated immunity responsible for the concomitant development of pathological signs of EAE. It may be concluded that the induction of classical signs of EAE requires specific and defined sequences capable of expressing both B cell and T cell functions.
Partial characterization of chicken Thy‐1 glycoprotein by monoclonal antibodies
Authors: French P.W. , Jeffrey P.L. 
Published: January 2005

AbstractA panel of monoclonal antibodies has been raised to Thy‐1 purified from chicken brain. They were produced by immunization of Balb/c mice with a Thy‐1‐enriched (Sephacryl B) fraction of a lentil lectin‐positive fraction from solubilized brain membrane proteins. Antibody‐secreting clones were found to be specific for Thy‐1 by enzyme‐linked immunosorbent assay (ELISA) and Western transfer and immunoblotting. Four of the monoclonal antibodies were of the IgG2b isotype, one was IgG1, and one was IgM. In additivity and competition ELISA, it was found that three of the antibodies bound to the same (or similar) epitopes, and three had different epitope specificities. These monoclonal antibodies have been used to examine the development and distribution of Thy‐1 in the central nervous system of the chicken.
The survival of adult mouse sensory neurons in vitro is enhanced by natural and synthetic substrata, particularly fibronectin
Authors: Smith R. A. , Orr D. J. 
Published: January 2005

AbstractPrimary cultures derived from adult mouse dorsal root ganglia have been maintained in the presence or absence of 5 × 10 −6M cytosine arabinoside for periods of up to 4 weeks. In cultures in which cytosine arabinoside is present, the non‐neuronal cell population is effectively reduced. When uncoated plastic substrata are used there is also a concurrent decrease in the number of neurons if the medium is supplemented with cytosine arabinoside. The effects on neuron survival of substrata coated with fibronectin, polyornithine, polylysine, and exudates prepared from mouse liver cells were studied. It was shown that neuronal densities similar to those with uninhibited media may be retained in the presence of cytosine arabinoside if fibronectin‐coated substrata are prepared. With the other coating agents neuronal survival was also enhanced but to a lesser extent. The study offers a means therefore of producing purer cultures of dorsal root ganglia neurons than has previously been possible from adult mammalian sources.
Nonresident macrophages in peripheral nerve of rat: Effect of silica on migration, myelin phagocytosis, and apolipoprotein E expression during wallerian degeneration
Authors: Müller H. W. , Minwegen P. 
Published: January 2005

AbstractThe selective toxicity of silica quartz dust to macrophages was used to assess the role of these cells in Wallerian degeneration and nerve repair. Left sciatic nerves of adult Wistar rats were crushed and one group of animals received repetitive intraperitoneal injections of silica (200 mg two times per week starting 1 day prior to injury), whereas the control group received saline. Unexpectedly, silica treatmen did not impair the initial invasion of (hematogenous) macrophages into the degenerating dital nerve stump as revealed by histological and immunocytochemical methods. However, 4 weeks after the lesion three specific events in Wallerian degeneration were significantly inhibited in silica‐treated animals: (1) inhibition of phagocytosis and degradation of myelin, (2) delay in disappearance of nonresient macrophages from regenerating nerve, (3) reduction of synthesis and/or secretion of apolipoprotein E in resting macrophages. On the other hand, axonal regrowth and remyelination were not affected by silica. These in situ experiments support and extend previous studies suggesting specific function for nonresident macrophages in wallerin degeneration of peripheral nerve.
Release of acetylcholinesterase from the caudate nucleus of the rat
Authors: de Sarno P. , Giacobini E. , Downen M. 
Published: January 2005

AbstractAcetylcholinesterase (AChE)can be released in the Perfusate of rat caudate nucleus (CN) slices by two different modes of stimulation, with electrical stimulation at 5Hz and with high concentrations of K+ (105 mM) using K+ ‐propionate. We were unable to demonstrate AChE release with lower K+ concentrations (50 mM); however, at this concentration the drop in AChEactivity seen in resting conditions was prevented. Practicfallyb all (95%) cholinesterase (ChE)found in the rat CN is AChE, which is reprersented by tow major molecular forms (4S and 10S). In the perfusate, only AChE activity could be detected. A comparison of acetylcholine (ACh) and AChE release showed that maximal 3H‐outflow and AChE release occurred at the same frequency (5 Hz), but the onsetof AChE release was delayed. With high K+ (105mM) depolarization, AChE release started after termination of the stimulation and continued for at least 50 min. These findings are consistent with the view that soluble form(s) of AChE can be slowly released from neurons under specific conditions of depolarization. In the caudate of the rat, the most likely sites for this release are processes of chlinergic interneurons. A hypothesis of AChE release is presented, and possible physiological and pathological implications of such a mechanism are discussed.
Topical application of morphine to the rat somatosensory corte produces analgesia to tonic pain
Authors: Soto‐Moyano R. , Galvez J. , Vallejos C. , Hernandez A. 
Published: January 2005

AbstractTopical application of 0.01 or 0.1% morphine solution to the somatosensory SI area of the rat cerebral cortex significantly decreased the pain intensity rating in the formalin test without producing motor side efects or senory deficits. Naloxone of morphine to the stirate cortex did not induce analogesia. It issuggested that the primary somatosensory SI area of the cerebral cortex plays a role in opiate pain control.
Adenosine stimulates cAMP‐mediated taurine release from LRM55 glial cells
Authors: Madelian V. , Silliman S. , Shain W. 
Published: January 2005

AbstractThe possible role of adenosine as a modulator or transmitter in the central nervous system was tested by measuring its effects on LRM55 astroglial cells. Two related cellular responses were measured–receptor activated increases in intracellular cAMP and cAMP‐mediated taurine release. Taurine is a neuroinhibitory amino acid that is taken up, stored, and released from primary cultures of astrocytes and astroglial cells. Three‐minute incubations of cells with adenosine caused a dosedependent accumulation of intracellular cAMP and release of the taurine (EC50 = 5.0 × 10−5 M and 1.6 × 10−6 M, respectively). That the cellular responses were mediated through the activation of specific adenosine receptors was indicated by the observations that the adenosine receptor antagonist isobutylmethylxanthine (IBMX) but not the beta‐adrenergic receptor antagonist 1‐propranolol inhibited responses to adenosine. The study of various adenosine analogs showed a rank order of potency (chloroadenosine = 5′‐(N‐ethyl)carboxamidoadenosine > N6‐(L‐2‐phenylisopropyl)‐adenosine > cyclohexyladenosine = cyclopentyladenosine) characteristic of the low affinity A2‐type adenosine receptors that have been associated with cAMP elevation in several tissues. These results indicate that, in addition to directly affecting neurons, adenosine may have a primary site of action on astroglial cells resulting in taurine release and subsequent inhibition of neuronal activity.
Ganglioside GM1 actions on cell‐substratum adhesion and DNA synthesis by cultured astroglial cells
Authors: Pettmann B. , Manthorpe M. , Varon Silvio 
Published: January 2005

AbstractCultures of rat astroglial (AG) cells treated with the ganglioside GM1 in serum‐free medium respond with an increase in DNA labeling and cell proliferation. However, GM1 doses above 60 μM cause decreasing DNA labeling to levels even below that determined in the absence of added GM1. Quantitative determination of cell numbers in 24‐hr cultures treated with various GM1 concentrations shows no loss of cells but a progressive shift in cell morphology from the usual flat to a rounded shape, suggesting a GM1‐induced progressive reduction in cell‐substratum adhesion. The rounded cells, which can be readily washed off the culture wells, do not carry out measurable DNA synthesis but do appear normal by several other biochemical measurements. All the GM1‐treated rounded cells can regain their flat morphology and resume DNA synthesis and cell replication if fetal calf serum is added to the medium. We conclude that modulation of cell adhesion is a major component of astroglial cell responses to exogenous ganglioside treatment.
Immortalization of bipotential glial progenitors and generation of permanent “blue” cell lines
Authors: Evrard C. , Galiana E. , Rouget P. 
Published: January 2005

AbstractThe transfer of the adenovirus 5 E1A gene into brain cells from rat embryos led to the establishment of phenotypically untransformed clonal glial cell lines. Some lines displayed properties of oligodendrocyte‐astrocyte progenitors. Their differentiation involved several steps that were dependent on culture conditions and cell interactions. Subsequently, a few lines were cotransfected with a vector carrying a modified dihydrofolate reductase gene and with the Escherichia coli lacZ gene. After selection for resistance to methotrexate, cell lines were derived that stably expressed the lacZ gene. These cells were individually detectable by histochemical staining for β‐galactosidase activity, even in the presence of other cells. These results suggest that this type of cell line could be of interest for further in vitro, and possibly transplant, studies of the differentiation and interactions of glial cells.