bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzyme changes in axon, myelin, and Schwann cells in injured sciatic nerve
Authors: Lapin Evelyn P. , Weissbarth S. , Maker H. S. , Lehrer G. M. , Weiss C. 
Published: January 2005

AbstractFour enzymes related to specific cell functions were assayed in rat sciatic nerve injury by crush (cr) or crush and ligation (cr‐lig) after 2, 7, and 15 days in situ. Enzyme activities in segments of sciatic nerve proximal and distal to the injury were compared to those in corresponding segments of the contralateral nerve. Choline acetyltransferase (CAT) activity in the distal portion decreased by 65% for cr and almost to zero for cr‐lig by day 7, while in the proximal portions CAT decreased to 70% of control values by 7 days and to 50% at 15 days after cr‐lig.The activity of the Schwann cell–myelin‐associated enzyme 2′,3′‐cyclic nucleotide phosphohydrolase (CNP) decreased slowly distal to the injury. Distal to both types of injury the lysosomal enzyme beta‐glucuronidase (GLR) increased six‐ to eightfold by 15 days. Proximal to injury GLR also increased (P cr × 2.5, P cr‐lig × 5) but the peak proximally was attained by day 7. Despite interruption of axonally transported enzymes, the activities of the metabolic enzyme creatine kinase (CK) increased distal to injury apparently reflecting changes in the functions of the Schwann cells. The loss of metabolic enzymes from the axonal compartment may be completely obscured by reciprocal changes in the nonneuronal compartments if the activity is present in both compartments.
Regional cell count and respiration in the brain of Rana catesbeiana
Authors: Yeaman R. R. , Potter Richard L. 
Published: January 2005

AbstractCell counts were made in three divisions of the bullfrog brain: (1) olfactory lobes‐telencephalon, (2) diencephalon‐mesencephalon, and (3) the hindbrain; average cellular respiration in potassium‐enriched Ringer solution and the rate of respiration in sodium‐free medium were tested for their possible relationship to the numbers of glia and numbers of neurons in each region. After restoring some of the sodium ions to sodium‐free minces, the percent increase in respiration was plotted for each brain segment and compared to the percent of glia per brain division to determine the glial respiratory contribution. Where glial numbers were greater, the potassium‐stimulated respiration was greater; where neuronal numbers were greater, the sodium‐free respiration was most prominent. The respiration increased most above the sodium‐free rate, when sodium ions were added or when the full amount of sodium was present, in the hindbrain, where the glia appear to metabolize more vigorously and the neurons least actively.
Glycoprotein properties of benzodiazepine receptors from calf cerebral cortex
Authors: Sherman‐Gold Rivka , Dudai Y. 
Published: January 2005

AbstractSeveral lectins (concanavalin A, wheat germ agglutinin, wax bean agglutinin, and phytohemagglutinin) induce aggregation and precipitation of deoxycholate‐solubilized benzodiazepine receptors from calf cerebral cortex. These receptors were also retained on columns of immobilized lectins. Photoaffinity labeling of the soluble benzodiazephine receptors prevented their interaction with lectins. Periodate treatment caused inactivation of benzodiazepine receptors which was partially prevented by diazepam and/or γ‐aminobutyric acid. The possible association of the drug‐binding site and the carbohydrate moiety is discussed.
Apparent turnover of norepinephrine in the intact rat brain estimated from its rate of appearance in the cerebroventricular compartment
Authors: Levitt Morton , Kowalik S. , Barkai A. I. 
Published: January 2005

AbstractThe apparent turnover of norepinephrine (NE) in the intact brain of urethane‐anesthetized rats was estimated in vivo from the rate of appearance of endogenous NE in the cerebroventricular compartment. Ventriculocibternal perfusion, a radioenzymatic assay for endogenous NE and isotope dilution of 3H‐NE were used to determine the rate of appearance (Ra) of NE. The effect of tranylcypromine, a monoainine oxidase (MAO) inhibitor and releasing agent on Ra of NE, was also studied. In control animals, the mean Ra value was 0.40 pmol/min. Pretreatment with tranylcypromine resulted in a threefold increase in the mean value for Ra, which was due to increased secretion of NE into the CSF. The results indicate that 90% of the NE entering the cerehroventricular compartment was removed. Pretreatment with tranylcypromine did not modify removal, thus suggesting that tranylcypromine has no effect on the physiological processes which regulate the removal of NE from the CSF.
Effects of excitatory amino acids, and of their agonists and antagonists on the release of neurotransmitters from the chick retina
Authors: Morán J. , Pasantes‐Morales H. 
Published: January 2005

AbstractEffects of glutamic, aspartic, and cysteic acid, and of kainic acid and N‐methyl aspartate on the release of labeled GABA, glycine, and taurine were examined in isolated, perfused chick retina. Glutamic acid (0.5‐2 mM), increased the release of 3H‐GABA by more than four times and that of 14C‐glycine by about two times. The release of GABA decreased 50% and that of glycine 95% in the presence of the antagonist of glutamic acid receptors, glutamate diethyl ester (300 m̈M). N‐methyl aspartate, used as an agonist of aspartic acid receptors, preferentially increased the release of GABA (seven times) over that of glycine (three times). The stimulatory effect of N‐methyl aspartate was antagonized by D‐α aminoadipate and by Mg. Kainic acid (10 m̈M) induced the release of glycine but not that of GABA. Cysteic acid failed to modify the release of any of the amino acids examined. The efflux of labeled taurine was practically unaffected by all the compounds utilized. The release of GABA by the excitatory amino acids and agonists was Ca‐independent but Na‐dependent, whereas the release of glycine was markedly Ca‐dependent. The evidence presented here suggests that experimental conditions activating receptors of excitatory amino acids differently affect the release of inhibitory amino acids.
Learning deficits on avoidance task and hippocampal lesions in area CA3 following intraperitoneal administration of 3‐acetylpyridine
Authors: Ozaki H. S. , Murakami T. H. , Shimada M. 
Published: January 2005

AbstractYoung adult mice of the ddN‐F26 strain were given a single intraperitoneal injection of 3‐acetylpyridine (3‐AP) at a dosage of 200 mg/kg body weight. Two weeks after this treatment, learning on avoidance task was tested with a training apparatus called a jump‐box. Each mouse was subjected to 30 trials of training per week for 3 or 4 weeks.Contrasted to untreated mice, the mean performance of the 3‐AP‐treated mice on avoidance training was significantly reduced in every weekly training session. However, since the learning scores of individual 3‐AP‐treated mice were highly varied, these mice were divided into several groups according to the characteristics of their learning patterns in order to analyze the relationships between learning ability and brain damage. It was found that there was a close association between the rate of learning deficits and the degree of destruction of the pyramidal cells in area CA3 of the hippocampus in mice treated with 3‐AP. The present data suggest that the area CA3 neurons play an important role on the acquisition of avoidance task and memory formation.
Possible role of increased brain methylation in methionine sulfoximine epileptogenesis: Effects of administration of adenosine and homocysteine thiolactone
Authors: Schatz R. A. , Wilens T. E. , Tatter S. B. , Gregor P. , Sellinger O. Z. 
Published: January 2005

AbstractAn intraventricular pulse of [14COOH]L‐methionine to mice pretreated with the convulsant L‐methionine‐dl‐sulfoximine (MSO) resulted in significantly higher than control specific radioactivity values of cerebral [14COOH]L‐methionine (Met), [14COOH]S‐adenosyl‐L‐methionine (AdoMet) and [14COOH]S‐adenosyl‐L‐homocysteine (AdoHcy). MSO administration (3 hr) also decreased brain steady‐state levels of Met, AdoMet, and AdoHcy.Following an intraventricular pulse of [3H‐methyl]L‐methionine, the levels of [3H‐methyl]phosphatidylmonomethylethanolamine and of membrane associated and soluble [3H‐methyl]carboxylmethylated proteins were increased over corresponding saline‐treated controls. The activity of cerebral histamine N‐methyltransferase was also increased after MSO treatment. The administration of a combination of adenosine and homocysteine thiolactone to MSO‐pretreated animals counteracted the MSO‐induced decreases in brain Met, AdoMet, and AdoHcy as well as the increase in histamine N‐methyltransferase activity. In addition, administration of adenosine together with homocysteine thiolactone decreased the incidence of, and increased the latency to MSO seizures, with the most effective anticonvulsant action occurring when cerebral AdoHcy levels were at their highest.
Glial contribution to amino acid content and metabolism of the deafferented dentate gyrus
Authors: Molin S.‐O. , Nyström B. , Haglid K. , Hamberger A. 
Published: January 2005

AbstractThe time course of tissue content and evoked release of endogenous amino acids was analyzed in the partially deafferented dentate gyrus of the rat hippocampus 2– 24 days following unilateral lesion of the perforant path. Amino acids in tissue extracts and perfusates were determined after precolumn derivatization and hplc separation. The astrocytic glial cell reaction was monitored with immunohistochemistry of S‐100.The tissue content of glutamate decreased significantly on the lesioned side, whereas only a moderate reduction in taurine, aspartate, and alanine occurred. Glutamine was significantly elevated at 7 days. The evoked efflux of glutamate was reduced at 2 and 7 days, whereas no change was seen at longer survival periods. The evoked release of GABA and aspartate increased on the denervated side after 12 and 24 days. The rate of carbon utilization into amino acid pools was followed with 14C‐glucose and 14C‐acetate. The incorporation of acetate showed a peak 2–9 days following lesion, which paralleled in time the hypertrophic glial cells. The incorporation of glucose decreased during this period. The metabolic events are discussed in relation to the morphological changes in synapses and glial cells.
Histochemical demonstration of cytoplasmic glycosaminoglycans in the macroneurons of the human central nervous system
Authors: Alvarado M. V. , Castejón H. V. 
Published: January 2005

AbstractThe presence of glycosaminoglycans (GAG) has been histochemically demonstrated in the CNS of various mammalian species. They have been related with some nerve functions as neurotransmitters storage and synaptic transmission. In the present paper, the histochemical properties of nerve cell cytoplasmic GAG were studied in several regions of adult human CNS. Samples of brain cortex, pons, upper medulla, and cerebellar cortex obtained by autopsy from subjects not dying after neurological diseases were fixed by immersion in glutaraldehyde, dehydrated with ethanol, and embedded in paraffin. The sections were stained with Alcian blue solutions adjusted to pH 2.5, 4.0, and 5.7. To the latter solution MgCl2 was added in increasing concentration from 0.05 to 1.2 M. Testicular hyaluronidase, neuraminidase, and ribonuclease were applied on simultaneous sections with their respective controls. The sequence of these reactions allowed us to demonstrate the presence of hyaluronic acid along chondroitin‐4‐ and/or 6‐sulphate in the cytoplasm of most nerve cells. The sulphated GAG showed certain variability in the various regions studied related specially with their grade of sulphation.
A combined flat‐embedding, HRP histochemical method for correlative light and electron microscopic study of single neurons
Authors: Aldes L. D. , Boone T. B. 
Published: January 2005

AbstractA simple and reproducible method is described for studying the morphology of the same neuron at the light and electron microscopic level. This method utilizes horseradish peroxidase histochemistry and a recently described flat‐embedding procedure wherein thin, aldehyde‐fixed sections are placed in resin between glass microscope slides pretreated with dimethyldichlorosilane. The significance of these combined methodologies for correlative light and electron microscopic studies of single neurons is discussed.
Concurrent determination of enzymatic activities and substrate concentrations in the melatonin synthetic pathway within the same rat pineal gland
Authors: Champney Thomas H. , Holtorf A. P. , Steger R. W. , Reiter R. J. 
Published: January 2005

AbstractThis study details the procedures involved in measuring a number of the components of indole metabolism within the pineal gland. Tryptophan, 5‐hydroxytryptophan, serotonin, N‐acetylserotonin, melatonin, 5‐hydroxyindoleacetic acid, N‐acetyltransferase (NAT) activity, and hydroxyindole‐O‐methyltransferase activity were measured by a combination of three techniques, which included microassays, radioimmunoassay, and high‐performance liquid chromatography. Determination of the melatonin synthetic pathway components within the same gland reduces the number of animals needed for studies and allows correlations between these constituents to be calculated. Very high degrees of correlation (r=0.91−0.99) are seen between those compounds which exhibit significant rhythms (serotonin, NAT activity, N‐acetylserotonin, and melatonin) when group means are compared. When correlations are calculated on a per‐animal basis throughout the experiment, moderate to high degrees of correlation (r=0.57−0.79) are found among those components that exhibit rhythms. However, when correlations are determined on a per‐animal basis at each time point, no significant correlations are found. One hypothesis accounting for these differences may be that changes occur in indole metabolism within the same pineal gland over a period of a few minutes.
Ionic mechanism of a hyperpolarizing glutamate effect on two identified neurons in the buccal ganglion of Aplysia
Authors: Sawada M. , Hara N. , Ito I. , Maeno T. 
Published: January 2005

AbstractThe ionic mechanism of a membrane effect of L‐glutamate on two identified neurons in the buccal ganglion of Aplysia kurodai was investigated with conventional microelectrode techniques and glutamate iontophoresis. Bath‐applied and iontophoresed glutamate hyperpolarized the membrane and increased the membrane conductance. The hyperpolarizing glutamate response decreased in amplitude and finally reversed its polarity by conditioning hyperpolarization. The reversal potential of the hyperpolarizing glutamte response was close to the ECl (−60 mV). The reversal potential changed by 22.4 mV when the external chloride concentration was altered by a factor of 5. The relationship between the iontophoretically applied current and the membrane conductance changes was suggestive of two glutamate molecules reacting with a single receptor site. The hyperpolarizing glutamate response was essentially unaffected by 2‐amino‐4‐phosphonobutyric acid (2‐APB), L‐proline, and quinuclidinyl benzilate (QNB). It was concluded that the hyperpolarizing glutamate response was generated by an activation of Cl− conductance.
Glial cells dissociated from newborn and aged mouse brain
Authors: Vernadakis A. , Mangoura D. , Sakellaridis N. , Linderholm S. 
Published: January 2005

AbstractChanges occurring with days in culture and cell passage in cultured glial cells derived from newborn vs aged (18‐mo) mouse cerebral hemispheres were compared. The activities of the enzymes glutamine synthetase (GS), an astrocyte marker, and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (CNP), an oligodendrocyte marker, were determined. In addition, glial fibrillary acidic protein (GFA) and glycerol phosphate dehydrogenase (GPDH) immunoreactivity was used to morphologically identify astrocytes and oligodendrocytes, respectively. In cultures derived from newborn mouse cerebral hemispheres, both GS and CNP activity and GFA‐positive and GPDH‐rhodamine‐positive cells were present with cell passage. In general, GS activity did not change in early cell passage in cultures from either newborn or aged mouse; in passage 5, GS was high in both sources of cell populations. CNP activity increased with cell passage in cultures derived from newborn mouse; in cultures derived from aged mouse CNP was low in the primary cultures, increased with cell passages 2 and 3, and declined with passages 4 and 5. The survival of astrocytes as shown by GS and the decline in oligodendrocytes as shown by CNP was also supported by an increase in the proportions of GFA and GPDH immunoreactive cells. We interpret the increase in GS activity to parallel the astrogliosis observed in vivo in the aging brain. Moreover, the decline in oligodendrocytes in culture may represent a shift of balance between glial cell types that appears to be influenced by the age of brain tissue and time in culture.
Vitamin content of some normal human brain segments
Authors: Baker Herman , Frank O. , Chen T. , Feingold S. , De Angelis B. , Baker E. 
Published: January 2005

AbstractNicotinates, pantothenates, riboflavin, vitamins B6 and B12′ free (acetyl) and total (free and bound) choline, biopterin, thiamin, biotin, methylated and nonmethylated folates in frontal, temporal, precentral, postcentral, and occipital cortex, thalamus, cerebellum, pons, basal ganglia, and substantia nigra were estimated. Nicotinates are significantly more concentrated in basal ganglia and thalamus than pons. Nonmethylated folate content is not significantly varied in brain segments; the pons contains more methylated folate. Riboflavin content is higher in the basal ganglia and temporal cortex than frontal cortex. Biotin is concentrated in pons and basal ganglia. Thiamin concentration is less in the postcentral cortex than the thalamus and substantia nigra. Biopterin is significantly higher in substantia nigra and basal ganglia than the other brain segments. Total choline content is high in substantia nigra, pons, and thalamus; free (acetyl) choline is significantly elevated in basal ganglia. B12 content is less concentrated in the cortex segments. B6 is highly concentrated in the basal ganglia. Pantothenate content is elevated in pons when compared to the various cortex segments and cerebellum.
Effects of exogenous GM1 and GD1a on S20Y neuroblastoma cells
Authors: Carine K. , Schengrund C.‐L. 
Published: January 2005

AbstractThe effects of exogenous GM1 and GD1a on S20Y murine neuroblastoma cells were assessed by monitoring morphology, tumorigenicity, mitotic index, and plating efficiency. S20Y cells were seeded at a density equivalent to 5 × 104 cells per 35‐mm tissue culture dish; 38–42 hr after seeding (preconfluent stage) the cells were treated for 12 hr with 100 μg of ganglioside per ml of medium in which the serum content was reduced from 10% to 0.5%. Analysis of the cell lipids indicated that added ganglioside became tightly associated with the membrane during the 12‐hr exposure. GM1 treatment resulted in increased projections on the cell surface and fine structures projecting from the cell processes. GD1a treatment resulted in a reduction in the cellular mitotic index. Plating efficiency was reduced by both GM1 and GD1a. Neither ganglioside affected tumorigenicity of the S20Y cells. Twelve hours after removal of the added ganglioside and exposure of the cells to normal medium, the ganglioside composition of the membranes from treated cells approached that of the controls, and the ganglioside‐induced effects had been reversed. These results suggest that addition of specific gangliosides induces different cellular responses and that these changes are dependent upon the continued presence of the ganglioside.
Inhibition of thalamic ventrobasal complex neurons by glutamate infusion into the thalamic reticular nucleus in rats
Authors: Mushiake S. , Shosaku A. , Kayama Y. 
Published: January 2005

AbstractIn urethane‐anesthetized rats a 0.36‐mm metallic cannula for infusion was positioned in the somatosensory component of the thalamic reticualar nucleus (sTR), where movement of the vibrissae evoked neuronal discharge. Infusion there of 0.125–0.5 μl of a 50 mM solution of glutamate over a 1‐min period suppressed both spontaneous and evoked discharge of neurons in the ventrobasal complex (VB), but only for those which also responded to vibrissal stimulation. VB neurons activated by somatosensory stimuli at other locations were unaffected. Thus, excitation of neurons in sTR inhibits those in VB, but the effect appears to be highly coordinated somatotopically.
Serotonin uptake and release from rat cerebellum in vitro
Authors: Beas‐Zarate C. , Sandoval M. E. , Feria‐Velasco A. 
Published: January 2005

AbstractSerotonin (5‐HT) uptake and release were analyzed in cerebellar fractions. Cerebellar P2 fractions and molecular layer homogenates are able to accumulate exogenous 5‐HT through an Na‐dependent, high‐affinity transport system. Molecular layer 5‐HT uptake, however, was totally dependent upon Na+, whereas the accumulation of the amine by P2 fractions from whole cerebellum was also carried out by an Na‐independent transport system. Ca++‐dependent release of recently accumulated 5‐HT was observed in both P2 fractions and molecular layer homogenates when depolarizing conditions were used. This release was blocked by ruthenium red and Mg++, two inhibitors of the Ca++ entry to the nerve endings induced by depolarization. The molecular layer homogenates released twice as much 5‐HT as did cerebellar P2 fractions, indicating that serotoninergic boutons in the cerebellar cortex might be located in the molecular layer. Our results suggest that 5‐HT might play a transmitter role in the cerebellum.
Analytical and preparative high‐performance liquid chromatography of gangliosides
Authors: Gazzotti G. , Sonnino S. , Ghidoni R. , Kirschner G. , Tettamanti G. 
Published: January 2005

AbstractAnalytical and preparative procedures are described for high‐performance liquid chromatography (HPLC) fractionation of gangliosides without previous derivatization. These procedures make use of a reversed‐phase Lichrosorb RB‐8 or μBondapak RP‐18 column, and of a mixture of acetonitrile and 5 mM phosphate buffer, at fixed or varying volume ratios, as solvent system. Peak elution from the column is monitored by flow through reading of absorbance at 195 nm. Under all the described conditions HPLC is capable of resolving all common gangliosides and of separating each of them into four molecular species containing C18‐sphingosine, C18‐sphinganine, C20‐sphingosine, or C20‐sphinganine.The analytical method has been successfully applied to fractionation of ganglioside mixtures from calf brain and to verification of homogeneity of singleganglioside preparations. It is suitable for quantitative purposes, with high sensitivity (detection limit, 0.1 nmole) and precision (SD less than 10% of mean values in the concentration range 0.1–50 nmoles). The semipreparative method, which provides successive cycles of analysis in a fully automated way, enables the preparation in 2–4 days of 100‐mg amounts of each molecular species starting from single gangliosides, like GM1 and GD1a. The preparative method makes use of acetonitrile‐phosphate buffer‐tetrahydrofuran as eluting solvent, and requires the addition to the starting ganglioside of the corresponding radioactive compound as tracer. This procedure, applied to GM1 ganglioside, is devised for processing up to 50 mg of ganglioside per analysis.