bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of proteolysis on the activity of the sodium channel in isolated lobster nerve membrane
Authors: Barnola Flor V. , Torres M. E. 
Published: January 2005

AbstractThe effect of emymatic proteolysis on structural and functional properties of the isolated lobster nerve membrane was investigated. The membranes were treated with diffcrcnt amounts of either trypsin or unspecific protease. Sodium channel activity was determined by measuring the veratridine‐tetrodotoxin‐sensitive sodium influx in proteoliposomes prepared with nerve membrane and soybean lipids. The changes in the membrane proteins were followed by electrophoresis in polyacrylamide gradient gels. From the densitometric scan of the gels the relative area for each protein was obtained, and the ratio of enzyme‐treated to control areas was evaluated. Under a similar degree of proteolysis catalyzed either by trypsin or by unspecific protease, the sensitive sodium influx is not affected by trypsin, whereas it is about 60% diminshed by the unspecific protease. In this condition thc zoncs corresponding to molecular weights of 240,000 and 166,000 daltons appear modified in the electrophoretic gels by both enzymes. The 117,000‐dalton range is modified only by the unspecific proteasc. Increasing trypsin concentration diminishes sodium influx about 60%; and the 240,000‐, 166,000‐, and 117,000‐dalton zoncs appear modified. A further increase of the protease concentration totally abolishes the sensitive sodium influx and modifies practically all of the membrane proteins. The present results indicate the rathcr high sensitivity of thc mcmbranc sodium channel activity to proteolytic action, and show that the membrane sites that respond to veratridine appear to be highly affected by proteolysis. In contrast, the tetrodotoxin receptor retains its binding capacity even after treatment of the membrane with proteasc conccntrations 1,000 times higher than those affecting the sensitive sodium influx [Benzcr and Raftery, 1972; Villegas et al, 1973].
Taurine, hypotaurine, and GABA uptake by cultured neuroblastoma cells
Authors: Holopainen I. , Kontro P. , Frey H. J. , Oja S. S. 
Published: January 2005

AbstractUptake of [3H]taurine, [3S]hypotaurine, and [3H]γ‐arninobutyric acid (GABA) was studied in ncuroblastoma C 1300 cells in Krebs‐Ringer‐Hepes‐glucose medium (pH 7.4). The uptakes consisted of nonsaturable penetration (taurine and hypotaurine) and two saturable transport components: high affinity for taurine, hypotaurine, and GABA and low affinity for hypotaurine and GABA. The affinity of the high‐affinity uptake was highest for hypotaurine but the transport capacity was greatest for taurine. GABA uptake was almost abolished by taurine and hypotaurine. Hypotaurine also strongly inhibited taurine uptake, whereas GABA had only a moderate inhibitory effect on taurine and hypotaurine uptakes. The mutual inhibition suggests that these amino acids use the same transport sites when entering the cells.
Rat cortex synaptic and nonsynaptic mitochondria: Enzymatic characterization and pharmacological effects of naftidrofuryl
Authors: Dagani F. , Gorini A. , Polgatti M. , Villa R. F. , Benzi G. 
Published: January 2005

AbstractIn order to investigate the in vivo pharmacological effects of the drug naftidrofuryl, we prepared populations of synaptic and nonsynaptic mitochondria from rat brain cortex. In these different mitochondrial populations the activities of citrate synthase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase, and glutamate dehydrogenase were evaluated. Except for glutamate dehydrogenase, the specific activities of the enzymes evaluated in the „free”︁ mitochondrial fraction were higher than those observed in the „synaptic”︁ SM1 and SM2 mitochondrial fractions, the difference between SM1 and SM2 fractions being significant. The in vivo administration of naftidrofuryl induced few and different changes in the various mitochondrial populations.
Interaction of catecholamine‐derived alkaloids with central neurotransmitter receptors
Authors: Nimit Y. , Schulze I. , Cashaw J. L. , Ruchirawat S. , Davis V. E. 
Published: January 2005

AbstractCatecholamine‐derived alkaloids of the simple tetrahydroisoquinoline, 1‐benzyltetrahydroisoquinoline and tetrahydroprotoberberine classes have been tested for their ability to inhibit the binding of seven different radioligands to neurotransmitter receptors of brain synaptic membranes. Alkaloids of all three classes were active in inhibiting 3H‐clonidine binding to α2‐adrenergic receptors. Stereoselectivity of tetrahydropapaveroline in binding to α2‐adrenergic receptors was evidenced by the marked activity of the S‐(—) isomer (IC50 = 0.65 m̈M) in comparison to the R‐(+) enantiomer (IC50 = 50 m̈M). The simple tetrahydroisoquinolines (3,4‐dihydroxytetrahydroisoquinoline and salsolinol), the four isomeric mono‐0‐methyl derivatives of 2,3,10,11‐tetrahydroxyberbine and tetrahydropapaveroline were the most potent inhibitors of 30H‐apomorphine binding to dopaminergic receptor agonist sites. The tetrahydroprotoberberines, as a class, were the most potent inhibitors of 3H‐spiroperidol binding to dopaminergic receptor antagonist sites and of 3H‐WB‐4101 binding to α1‐adrenergic receptors. The 1‐benzyltetrahydroisoquinolines exhibited varying degrees of interaction with β1‐adrenergic receptors. Tetrahydropapaveroline (IC50 = 0.3 m̈M) was the most active of the 24 alkaloids tested in inhibiting binding of 3H‐dihydroalprenolol to β1‐adrenergic receptors. None of the alkaloids significantly affected 3H‐QNB binding to muscarinic‐cholinergic receptors, and selected alkaloids from each class interacted only moderately with serotonergic receptors.
Investigations on myelination in vitro: IV. „Myelin‐Like”︁ or Premyelin Structures in Cultures of Dissociated Brain Cells From 14–15‐Day‐Old Embryonic Mice
Authors: Sarliève L. L. , Fabre M. , Susz J. , Matthieu J. M. 
Published: January 2005

AbstractThe present study reports ultrastructural and biochemical data characteristic of myelin‐related structures in 30‐ to 41‐day‐old cultures of dissociated brain cells from 14‐ to 15‐day‐old embryonic mice. Multilayered membranous material was identified and displayed an alternation of electron‐lucent and electron‐dense lamellae with a periodicity of 102 Å. In these membranes, typical myelin constituents like basic protein, cerebrosides, sulfatides, and CNPase could be identified. Although we are still unable to distinguish if these membranes are premyelin or compact myelin, which could be partly degraded, these results indicate that cultured mouse brain cells retain, to a certain extent, potential to produce myelinrelated membranes.
Differential effects of interferon on ventromedial hypothalamus and dorsal hippocampus
Authors: Prieto‐Gomez B. , Reyes‐Vazquez C. , Dafny N. 
Published: January 2005

AbstractThree incremental doses of recombinant α‐interferon (IF) were applied iontophoretically to hippocampal and hypothalamic cells. IF produced a dose‐dependent long‐lasting excitation in hippocampal neurons, whereas, in the hypothalamus α‐IF elicited biphasic responses. The highest IF currents induced changes in the amplitude of the action potentials on both structures. Our observations suggest that IF could have a selective effect on the specific areas studied.
Protective effect of taurine and zinc on peroxidation‐induced damage in photoreceptor outer segments
Authors: Pasantes‐Morales H. , Cruz C. 
Published: January 2005

AbstractExposure of isolated frog rod outer segments (ROS) to ferrous sulfate in a Krebsbicarbonate medium causes a time‐dependent disruption of the membrane organization of the discs. Ferrous sulfate also causes ROS swelling and aggregation. Addition of taurine (5–20 mM) and zinc sulfate (250 μM) to the incubation medium markedly protected ROS from the disrupting effect of ferrous sulfate. Of other amino acids tested, only β‐alanine had a protective effect on ROS structure. Ferrous sulfate caused an increase in lipid peroxidation, measured by malonaldehyde formation. The protective effect of taurine and zinc is not accompanied by a reduction of lipid peroxidation. Water accumulation occurs as a consequence of the peroxidative action of ferrous sulfate, and this effect was counteracted by taurine and zinc. Ferrous sulfate did not cause damage to ROS structure when incubation was carried out in sucrose‐HEPES. Sodium, chloride, and bicarbonate ions caused ferrous sulfate to disrupt ROS structure. It is concluded that taurine and zinc protect ROS membranes from ion and/or water entry occurring as a consequence of membrane lipid peroxidation.
Production and characterization of monoclonal antibodies to the myelin glycolipid sulfatide
Authors: Hofstetter W. , Bologa L. , Wetterwald A. , Z'graggen A. , Blaser K. , Herschkowitz N. 
Published: January 2005

AbstractSulfatide is enriched in the myelin sheath and accounts for 5% of the total lipids in this membrane. In the present work we describe the production and characterization of mouse monoclonal antibodies against sulfatide. The antibodies were detected and characterized in a previously described ELISA test system.The clone AIC3IA2 produced antibodies of the IgG3 class with high specificity for sulfatide. These antibodies showed almost no cross‐reactivity with galactocerebroside or with any of the other lipids we tested. When used with the peroxidase antiperoxidase technique the antibodies stained a cell population either in fixed or unfixed brain cell cultures, indicating a surface localization of sulfatide in the respective cell population. In double‐staining experiments the stained cell population was identified as myelin basic protein‐positive oligodendrocytes.
An SEM examination of granule cell migration in the mouse cerebellum
Authors: Grovas A. C. , O'Shea K. S. 
Published: January 2005

AbstractThe inward migration of external granule cells (EGC) from the pial surface of the developing cerebellum to from the (internal) granule cell layer was examined using SEM. Cerebella from male mice ranging in age from days 1–20 were fixed, then fractured through the developing pyramid region.EGC were initially unspecialized cells, forming 2–3 layers at the pial surface. EGC layers increased to 6–8, granule cells in the deeper regions elongated, and a prominent space formed between superficial and deep (premigratory) strata. During peak migration (days 8–12), nests of 4–6 EGC were associated with Bergmann glial fibers (BF) of the Golgi epithelial cells, which crossed molecular and EGC layers to terminate as spiny endfeet at the pial surface. Fibrils of extracellular material (ECM) often linked both premigratory and migrating EGC with a nearby BF. The molecular layer thickened considerably and the parallel fibers were traversed by an increasing number of Bergmann fibers and Purkinje cell processes during this period. As active migration slowed (days 13–20) and EGC reached their destination below the Purkinje cell layer, they lost their polarity and were enmeshed in ECM.The role of the Bergmann fibers and extracellular material in granule cell migration is considered.
Inhibition in corticotrophin and corticosterone secretion following photic stimulation in rats with 6‐hydroxydopamine injection into the medial forebrain bundle
Authors: Feldman S. , Melamed E. , Conforti N. , Weidenfeld J. 
Published: January 2005

AbstractChanges in corticotrophin (ACTH) and corticosterone (CS) serum levels, were examined in rats in which either 6‐hydroxydopamine or vehicle were injected into the medial forebrain bundle (MFB) and which were sacrificed by decapitation 14 days later. The injection of the neurotoxin, which depleted very significantly the norepinephrine (NE) content of the mediobasal hypothalamus, elevated significantly the basal levels of serum ACTH and CS, but inhibited the rise in the levels of these hormones following photic stimulation. These results would suggest that the hypothalamic NE system has normally an inhibitory effect on basal ACTH and CS secretion and that the hormonal response to photic stimulation is mediated by that system and possibly by NE MFB fibers.
Cytosolic gangliosides of rat brain: Their fractionation into protein‐bound complexes of different ganglioside compositions
Authors: Sonnino S. , Ghidoni R. , Fiorilli A. , Venerando B. , Tettamanti G. 
Published: January 2005

AbstractThe sialic acid moiety of rat brain cytosolic gangliosides was radiolabeled by intracranial injection of N‐(3H)acetylmannosamine. Upon ammonium sulphate fractionation, Sepharose 6B gel filtration, and hydroxylapatite‐cellulose chromatography, ganglioside‐bound radioactivity of brain cytosolic extract followed the behavior of protein and not that of purified gangliosides. This indicates that cytosolic gangliosides occur as ganglioside‐protein complexes.By application of hydroxylapatite‐cellulose column chromatography, fractions were obtained having different ganglioside composition. In particular, one fraction contained GM1, one GD1a, and one GT1b with a ganglioside homogeneity better than 95% in each fraction. This indicates the occurrence in brain cytosol of a GM1‐protein complex, a GD1a‐protein complex, and a GT1b‐protein complex.
Gangliosides of human spinal cord: Aberrant composition of cords from patients with amyotrophic lateral sclerosis
Authors: Dawson G. , Stefansson K. 
Published: January 2005

AbstractThe ganglioside content of formalin‐fixed human spinal cords and fresh human spinal cords was found to be both quantitatively and qualitatively similar. However, the spinal cord was found to be heterogeneous with respect to ganglioside content. In particular, a gradient of GD1a was observed, increasing from a low content in the cervical region to a relatively high content in the sacral region. Comparison of the ganglioside content of nine normal spinal cords and nine spinal cords from clinically diagnosed amyotrophic lateral sclerosis (ALS) patients revealed no major quantitative differences, but the unique presence of three additional gangliosides in ALS spinal cords. One of these was tentatively identified as sialosylglobotetraosylceramide and was absent from eight of nine control spinal cord samples, the sole exception being the cord from a 97‐year‐old female.
Differential expression of gangliosides on the surfaces of myelinated nerve fibers
Authors: Ganser A. L. , Kirschner D. A. 
Published: January 2005

AbstractThe binding of cholera and tetanus toxins to receptors on the surfaces of teased nerve fibers was used to localize GM1 and G1b‐series gangliosides, respectively, by immunocytochemical methods. Native fibers and fibers treated with various hydrolytic enzymes to degrade specific surface components were studied. With native fibers, both toxins bound abundantly to nodes of Ranvier and poorly to the most external, internodal Schwann cell surfaces. Treatment of the fibers with proteases, hyaluronidase, and chondroitin ABC lyase neither eliminated receptors at the nodes nor unmasked receptors over the internodes. The axolemma underlying the paranodal or internodal myelin, exposed by extensive treatment with protease, bound both toxins in large amounts. Neuraminidase action induced cholera toxin receptors on the Schwann cell surface; these receptors were insensitive to protease. The results indicate that GM1 and G1b‐series gangliosides are predominantly localized to axonal and glial structures of the node of Ranvier and to paranodal/internodal axolemma, and that polysialogangliosides not of the G1b‐series are present on the internodal Schwann cell surface.
Biosynthesis of gangliosides in the developing chick embryo retina
Authors: Cortassa S. , Panzetta P. , Maccioni H. J. F. 
Published: January 2005

AbstractChick embryo retinas were cultured with [3H]glucosamine on each day between days 6 and 12 of development. The total labeling of gangliosides decreased from day 6 to day 12. The decrease was mostly due to the decrease in the labeling of disialosyllactosylceramide (GD3), which diminished to less than 2%, while the labeling of the disialoganglioside GD1a decreased to about 30%. Labeling of endogenous gangliosides by incubating retina homogenates with CMP‐[3H]N‐acetylneuraminic acid, in addition to showing a decrease in the labeling of GD3, showed a twofold increase in the labeling of GD1a. The changes in the pattern of labeling correlated with the decrease of both the incorporation of [3H]thymidine into DNA and the activity of CMP‐NeuAc:GM3 sialosyltransferase and with the increase of both the activities of UDP‐Ga1NAc:GM3 N‐acetylgalactosaminyltransferase and choline acetyltransferase. The results suggest that the shift in the pattern of labeling of gangliosides occurs in association with the transition from the proliferative to the nonproliferative state of neuronal cells.Retinas at each age cultured with [3H]glucosamine for 22 hr maintain the radioactivity in gangliosides for at least 4 additional days in culture. This indicates that within this developmental interval there is not a period characterized by having a high turnover rate of gangliosides.
Dorsal root ganglia and nerve growth factor: A model for understanding the mechanism of GM1 effects on neuronal repair
Authors: Leon A. , Benvegnù D. , Toso R. Dal , Presti D. , Facci L. , Giorgi O. , Toffano G. 
Published: January 2005

AbstractThe experimental strategy of adding monosialoganglioside GM1 to a culture medium of fetal chick dorsal root ganglia (DRG) was utilized as a model system in which to examine the potential role of GM1 in modulation of neuronal cell responsiveness to nerve growth factor (NGF). Data indicate that the addition of GM1 to DRG explants or to DRG dissociated neuronal cells in culture enhances NGF‐induced neurite outgrowth, neurite complexity, and neuronal cell survival following NGF withdrawal. The GM1 molecule apparently facilitates the acquisition or maintenance of the NGF‐induced specific neuronal properties. Results are consistent with the hypothesis that the presence of GM1 molecules on the neuronal cell surface, either endogenous or following stable insertion of exogenous molecules, plays a prominent role in the modulation of functional neuronal cell behavior in response to varying neuronotrophic signals. This may prove to be relevant for the comprehension of GM1 effects on the facilitation of central nervous system repair processes.
Tryptophan fluorescence properties of cholera toxin upon interacting with ganglioside GD1b
Authors: Mestrallet M. G. , Bennun F. R. , Maggio B. , Cumar F. A. 
Published: January 2005

AbstractA blue shift of the tryptophan fluorescence emission spectra of cholera toxin or the B protomer is induced by disialoganglioside GD1b with a capacity similar to that of monosialoganglioside GM1. Both gangliosides were also capable of decreasing or reversing the fluorescence quenching by iodide ion of the toxin. The quenching constants (Ksv) for the toxin fluorescence in absence of gangliosides was 2.8 M−1; in presence of GM1 or GD1b, Ksv was 0.8 M−1 and 0.7 M−1, respectively. Gangliosides GD1a and GT1b were unable to decrease the quenching effect. The results suggest that GD1b induces a perturbation in the tryptophan environment of the toxin molecule similar to that induced by GM1.
Effects of ganglioside treatments on lesion‐induced behavioral impairments and sprouting in the CNS
Authors: Fass B. , Ramirez J. J. 
Published: January 2005

AbstractRecent findings suggest that exogenous gangliosides improve recovery of a learned behavior (alternation in a T‐maze) which is thought to be related to sprouting after lesions of the entorhinal cortex. In the present investigation, we studied an unlearned behavior (the open‐field hyperactivity resulting from bilateral entorhinal lesions) to evaluate whether ganglioside treatments reduce the severity of initial postlesion impairments or improve recovery. We also examined whether the treatments enhance the sprouting of septodentate fibers which parallels the recovery of open‐field activity. The typical behavioral changes induced by bilateral entorhinal lesions include hyperactivity, reduced habituation of activity, and a gradual time‐dependent return toward control levels. We found that rats treated with total brain gangliosides (30 mg/kg) showed a smaller lesion‐induced increase, consistently lower levels, and greater within‐session habituation of activity than did saline‐treated counterparts. Control rats treated with gangliosides did not exhibit a reduction in activity, suggesting that the effect was on lesion‐induced hyperactivity rather than on activity, per se. Ganglioside‐treated rats showed a slight, but consistently smaller lesion‐induced sprouting response by the septodentate pathway than did untreated counterparts at all postlesion intervals examined (3, 5, 7, and 10 days). The present findings indicate that ganglioside treatments reduce the severity of the initial behavioral effects after entorhinal lesions without enhancing the sprouting by septodentate fibers.
Reduction of cerebral edema with GM1 ganglioside
Authors: Karpiak S. E. , Mahadik S. P. 
Published: January 2005

AbstractAdministration of exogenous gangliosides has been reported to accelerate neurite outgrowth in vitro, and to enhance peripheral nerve regeneration and central nervous system recovery subsequent to damage. After injury, facilitation of CNS recovery with GM1 ganglioside treatment has been postulated to be due to enhanced neuronal regeneration. Since maximal recovery is achieved when experimental animals are treated before injury with GM1 ganglioside, an alternative or parallel mechanism is that gangliosides are “protecting” the CNS by limiting the extent of damage (ie, cell loss, process degeneration, membrane disruption). This may be due to a reduction in the edema subsequent to injury.In this study, rats were treated for 2 days with 20 mg/kg/day of GM1 ganglioside. On the third day they were subjected to a unilateral lesion (mechanical) of one cerebral hemisphere and given another 20 mg/kg of GM1. On the fourth day brains were removed for analysis of edema resulting from the injury. In treated animals there was a significant reduction in edema as measured either in the entire injured hemisphere (23%) or in the area of injury (33%). No effect was seen outside the damaged area. Since exogenous gangliosides can spontaneously “insert” into membranes, it is postulated that the effect of the GM1 may be due to alterations of membrane processes (eg, lipid hydrolysis, phospholipase activation, levels and membrane action of arachidonic acid, ionic permeation) that are characteristic of edema.
Monoclonal antibody to intermediate filament proteins in astrocytes
Authors: Pixley S. K. R. , Kobayashi Y. , de Vellis J. 
Published: January 2005

AbstractA monoclonal antibody was developed using rat astrocytes purified in vitro as the starting antigenic material. Selection of the monoclonal was on the basis of astrocyte binding specificity in brain sections using indirect immunofluorescence techniques. The antibody (RBA2) that was chosen was specific for astrocytes in that it did not stain neurons or oligodendrocytes in frozen brain sections. It did, however, show binding to vascular smooth muscle and meningeal cells. The antigenic determinant(s) was determined to be on filaments of the intermediatesize class in cultured astrocytes and fibroblasts. From analysis of binding patterns in various tissues and in immunoblots, it was found that RBA2 cross‐reacted strongly with glial fibrillary acidic protein (GFAP) and desmin. There was a weaker cross‐reactivity to a vimentin‐associated component. It is proposed that this antibody can be used as an astrocyte and blood vessel marker in brain sections, a vimentin marker in cultures and as a probe of intermediate filament composition and distribution.