bluuebunny/crossref_metadata_2025_split huggingface dataset:
RAT ADRENAL DOPAMINE‐β‐HYDROXYLASE PURIFICATION AND IMMUNOLOGIC CHARACTERISTICS
Authors: Grzanna R. , Coyle J. T. 
Published: October 2006

Abstract—Dopamine‐β‐hydroxylase (DBH) was purified from rat adrenal medulla by a series of steps including sedimentation of membranes, extraction with n‐butanol, ammonium sulfate fractionation, gel chromatography and ion‐exchange chromatography. Disk gel electrophoresis revealed two protein bands, both of which were active. Antiserum was prepared against homogeneously purified bovine adrenal and rat adrenal DBH: Ouchterlony immunodiffusion, enzyme neutralization and complement fixation tests demonstrated that the respective homologous antisera were monospecific and of high titer. Antiserum to bovine DBH was only 2‐ to 3‐fold more potent than pre‐immune serum in inhibition of rat DBH activity. Complement fixation tests demonstrate that antiserum to bovine DBH has a 25,000‐fold lower immunoreactivity with rat DBH than with bovine DBH.
SEROTONIN BINDING PROTEIN: ENHANCEMENT OF BINDING BY Fe2+ AND INHIBITION OF BINDING BY DRUGS12
Authors: Tamir Hadassah , Klein Athalia , Rapport Maurice M. 
Published: October 2006

Abstract—The binding of serotonin to a soluble, high affinity binding protein, present in synaptosomes and associated with serotonergic tracts, has now been studied for the effects of metallic ions and various drugs. At optimal concentration (10‐4 M) of Fe2+ the enhancement of binding was close to 20‐fold. A much smaller effect was noted with Cu2+. With other ions (Fe3+, Mn2+, Co2+, Ni2+, Cr3+, Mg2+, Ca2+) little or no effect was seen. For the effect with Fe2+. preincubation was required (10 min, 25°C) and concentrations higher than 10‐4M were inhibitory. Studies based on equilibrium dialysis show that the effect of Fe2+ was on the affinity of the binding of serotonin to the protein, rather than on the binding capacity. In polydcrylamide gels at pH 8.6 the migratory properties of thc serotonin‐protein complex formed in the presence of Fe2+ differ from those of the complex formed without Fe2+. Nucleotides (ATP, GTP, ADP, AMP) inhibited thc binding. The effects of several classes of drugs (inhibitors of biogenic amine storage and uptake, psychotomimetics, MAO) inhibitors and drugs binding to contractile proteins) were also studied. The only effective inhibitors of serotonin binding were reserpine, vinblastine and CZ‐74, which caused 50% inhibition at 2 × 10‐6 M, 7.5 × 10‐6 M and 0.2 × 10‐6M respectively.
NONDIALYZABLE SULFATED SIALOGLYCOPEPTIDE FRACTIONS DERIVED FROM BOVINE HEIFER BRAIN GLYCOPROTEINS. ISOLATION, CHARACTERIZATTON AND CARBOHYDRATE‐PEPTIDE LINKAGE STUDIES1
Authors: Allen W. S. , Otterbein Elizabeth C. , Varma R. , Varma R. S. , Wardi A. H. 
Published: October 2006

Abstract—The nondialyzable sialoglycopeptides dcrived from defatted, protease digested whole boyine heifer brain tissue were isolated and characterized. The partially purified bovine heifer brain tissue were isolated and characterized. The partially purified sialoglycopeptide mixtures contained 7‐8% ester sulfate. The amount of nonsulfated material present was of the order of 15%. The total mixture was fractionated by anion exchange chromatography on AG1‐X2(CI‐) using a sodium chloride gradient to yield twelve fractions all of which contained ester sulfate to varying degrees (5.6‐21.9%).The molecular size of the fractions ranged from molecular weights of 10,400‐12,500. The molar sulfate/galactose plus glucosamine ratios ranged from 0.3 to 1.1. Carbohydrate peptide linkage studies of the fractions by treatment with 0.2 M‐NaOH‐O.3 M‐NaBH4 led to the destruction of a portion of the threonine, serine and galactosamine and the appearance in acid hydrolysates of α‐amino‐n‐butyric acid and galactosaminitol with an increase in alanine. Partial acid hydrolysis of the most abundant sialoglycopeptide liberated detectable amounts of 2‐acetarnido‐1‐(L‐4‐aspartamido‐)‐1,2‐dideoxy‐β‐D‐ glucose. These results indicated that the GalNac at the reducing end of the alkali labile carbohydrate prosthetic groups were linked O‐glycosidically to thc hydroxyl groups of threonine and serine and the alkali‐stable region of the principal sialoglycopeptide involves N‐acetylglycosaminyl‐asparagine linkages. Mild acid hydrolysis of the alkali‐stable portion of the sulfated fractions indicated that the ester sulfate was confined to the alkali‐stable region and exists as galactose 6‐O‐sulfate and N‐acetylglucosa‐ mine 6‐O‐sulfate, structural fcatures similar to those present in rat brain glycopcptides (Markgolis & Margolis, 1970; Margoliset al.; 1972). Fucose and ester sulfate were confined to the alkali‐stable region while mannose was located in both the alkali‐labilc and alkali‐stable regions of the sialoglyco‐peptide fractions.
CENTRAL DOPAMINERGIC AND SEROTONINERGIC SYSTEMS IN THE REGULATION OF ADRENAL TYROSINE HYDROXYLASE1
Authors: Quik Maryka , Sourkes T. L. 
Published: October 2006

Abstract—Administration of the dopamine receptor agonists apomorphine, piribedil and bromocryptine caused an increase in adrenal tyrosine hydroxylase (TH; tyrosine‐3‐monooxygenase, EC 1.14.16.2) which could be partially abolished by prior injection of the dopamine blocker haloperidol. Injection of L‐dihydroxyphenylalanine, along with the decarboxylase inhibitor carbidopa, also led to a highly significant increase in adrenal TH activity. Intraventricular injection of 5,7‐dihydroxytryptamine (DHT), which destroys serotonin neurons, doubled adrenal TH activity in both normal and hypophysectomized rats. Splanchnicotomy abolished this effect of DHT. The increase in enzyme activity mediated by DHT could be partially prevented by peripheral administration of L‐5‐hydroxytryptophan together with carbidopa. Blockade of serotoninergic functions with the antagonist methiothepin also increased adrenal TH activity. The interrelationship between the dopamine and the presumed serotonin system was investigated. Intraventricular injection of 6‐hydroxydopamine partially prevented the DHT‐induced increase in adrenal TH activity. Administration of haloperidol to DHT‐treated rats had the same effect. This suggests that an intact dopaminergic system is required. When DHT and either apomorphine or piribedil were adminstered simultancously the dopamine agonist‐induced increase was potentiated. An intact serotoninergic system is therefore not required for dopamine function.Thus, the increase in adrenal TH activity is associated with either stimulation of central dopamine receptors or destruction of serotonin neurons. It is suggested that dopaminergic and serotoninergic systems are involved in the regulation of adrenal TH and that these systems have net excitatory and inhibitory roles, respectively. Furthermore, the present evidence favors the view that the interaction between the two systems is sequential, with the serotonin system preceding the dopamine one.
HOG CEREBELLAR d‐AMINO ACID OXIDASE AND ITS HISTOCHEMICAL AND IMMUNOFLUORESCENT LOCALIZATION1
Authors: Weimar W. R. , Neims A. H. 
Published: October 2006

Abstract— Hog cerebellar d‐amino acid oxidase (d‐AAO; EC 1.4.3.3) has been purified to homogeneity. The enzyme was found to be indistinguishable from crystalline hog kidney d‐AAO by a number of criteria, including electrophoresis in both cationic and anionic discontinuous buffer systems, FAD and sulfhydryl contents, and monomer molecular weights of about 40,000 as determined by SDS disc gel electrophoresis. Both preparations exhibited similar specific activities (23 μmol d‐ala oxidized min−1 mg−1 protein), substrate specificities, and susceptibilities to competitive inhibitors.Rabbit antisera were prepared against each enzyme preparation. Double immunodiffusion revealed no antigenic differences between the two when antiserum against either preparation was used. Although a soluble protein, d‐AAO activity in cerebellum is particulate.Two methods were utilized to study the histological localization of d‐AAO activity in hog cerebellum: peroxidase‐coupled histochemistry and immunofluorescence. The histochemical procedure seems specific for d‐AAO since l‐amino acids are inert and known competitive inhibitors of the purified flavoenzyme prevent staining. Rabbit antiserum prepared against purified hog cerebellar d‐AAO was visualized indirectly with fluorescein‐labeled goat antirabbit IgG antiserum. Control experiments with serum from unimmunized rabbits were negative.The results of both techniques were identical in three respects: (1) d‐AAO was observed in many fibers emanating from cerebellar white matter; the white matter itself did not exhibit d‐AAO, despite presence of the oxidase by biochemical assay; (2) intense d‐AAO activity (or antigen) was found in mossy fiber rosettes (glomeruli) in the granular layer; (3) a peculiar and intense localization of d‐AAO was noted at the level of, but not within, the Purkinje cell soma. The molecular layer was essentially devoid of d‐AAO histochemical activity except for minimal staining near the pial surface. However, the more sensitive immunofluorescent technique revealed d‐AAO containing fibers in the molecular layer running parallel to each other and perpendicular to the pial surface; the relatively large size and small number of these fibers do not suggest identification as granule cell axons. No d‐AAO has been found in granule cell soma, Golgi Type‐II cells, or Purkinje cell soma. These results are discussed in terms of the localization of d‐AAO in mossy fibers and their terminals and in certain cell‐type(s) of cerebellar origin.
STRUCTURAL AND IMMUNOLOGICAL PROPERTIES OF NEURON SPECIFIC PROTEIN (NSP) FROM RAT, CAT AND HUMAN BRAIN: COMPARISON TO BOVINE 14‐3‐2
Authors: Marangos P. J. , Zomzely‐Neurath Claire , Goodwin F. K. 
Published: October 2006

Abstract— Neuron specific protein (NSP) has been isolated from cat (NSP‐C) and human (NSP‐H) brain utilizing the purification procedure described for rat brain 14‐3‐2 (Marangoset al., 1975a,b,c), a protein which is now designated NSP‐R. The protein as isolated from cat and human brain has a molecular weight of approx 80,000 as determined by sedimentation equilibrium. Sedimentation studies done in the presence of 6mg‐HCl and 0.2%β mercaptoethanol yields a protomer M.W. of approx 40,000 for both preparations establishing the dimeric nature of each. The subunits appear identical in each case since one band is observed upon electrophoresis of either preparation in the presence of 8 M‐urea. NSP‐C and NSP‐H have identical isoelectric points of 4.7 making them slightly more acidic than NSP‐R (pi = 5.0).Comparison of NSP‐C and NSP‐H with NSP‐R and bovine 14‐3‐2 by electrophoretic and immunological criteria revealed that the cat, human and bovine proteins were very similar. NSP‐R can be distinguished from the other three preparations electrophoretically and immunologically. The protomer unit of NSP‐R differs in amino acid composition from that of the cat, human or bovine proteins since the former can be completely resolved from any of the latter three preparations on 8 M‐urea polyacrylamide gels. The data indicate that NSP and bovine 14‐3‐2 are probably homologous proteins, and establish the general structural properties of NSP.
CARRIER MEDIATED BLOOD‐BRAIN BARRIER TRANSPORT OF CHOLINE AND CERTAIN CHOLINE ANALOGS
Authors: Cornford Eain M. , Braun Leon D. , Oldendorf William H. 
Published: October 2006

Abstract—Blood‐brain barrier (BBB) transport of choline and certain choline analogs was studied in adult and suckling rats, and additionally compared in the paleocortex and neocortex of adult rats. Saturable uptake was characterized by a single kinetic system in all cases examined, and in adult rat forebrains we determined a Km= 442 ± 60 μM and Vmax= 10.0 ± 0.6 nmol min‐1 g‐1. In 14–15‐day‐old suckling forebrains a similar Km (= 404 ± 88 μM) but higher Vmax (= 12.5 ± 1.5 nmol min‐1 g‐1) was determined. When choline uptake was compared in two regions of the forebrain, similar Michaelis‐Menten constants were determined but a higher uptake velocity was found in the neocortex (i.e. neocortex Km= 310 ± 103 μM and Vmax= 12.6 ± 2.8 nmol min‐1g‐1; paleocortex Km= 217 ± 76 μM and Vmax= 7.2 ± 1.5 nmol min‐1 g‐1).Administration of radiolabelled choline at low (5 μM) and high (100 μM) concentrations, followed by microwave fixation 60 s later and chloroform‐methanol‐water separations of the homogenized brain did not suggest a relationship between concentration and the appearance of label in lipid or aqueous fractions as observed in another in‐vitro study elaborating two‐component kinetics of choline uptake. It was observed that 60s after carotid injection 12–14% of the radiolabel in the ipsilateral cortex was found in the chloroform‐soluble fraction.Hemicholinium‐3 (Ki= 111 μM), dimethylaminoethanol (Ki= 42 μM), tetraethyl ammonium chloride, tetramethyl ammonium chloride, 2‐hydroxyethyl triethylammonium iodide, carnitine, normal rat serum, and to a lesser extent lithium and spermidine all inhibited choline uptake in the BBB. Unsubstituted ammonium chloride and imipramine did not inhibit choline uptake.No difference was observed in blood‐brain barrier choline uptake of unanesthetised, carotid artery‐catheterized animals, and comparable sodium pentobarbital‐anesthetized controls.
BLOCKADE OF FAST AXONAL TRANSPORT BY DIPHTHERITIC DEMYELINATION IN THE CHICKEN SCIATIC NERVE
Authors: Kidman Antony D. , Dolan Louise , Sippe H. Jane 
Published: October 2006

Abstract—Chicken sciatic nerves undergo demyelination following intraneural injection of diphtheria toxin due to a lesion at the site of injection. Paresis occurs after 1 week and lasts for approx 3 weeks; at the height of the lesion we injected [14C]Ieucine into the ventral horn cells of the spinal cord and followed the axonal transport of fast flowing labelled proteins down the sciatic nerve fibres making measurements of flow rates at two different times. The results showed the fast flowing labelled proteins were blocked at the demyelination site. We measured total protein in the nerves and examined them histologically to confirm the lesion. Further studies are in progress on the post synaptic muscle cells and the impaired nerves.
SOME PROBLEMS INHERENT IN TRANSPORT STUDIES IN SYNAPTOSOMES
Authors: Wheeler D. D. 
Published: October 2006

Abstract—A technique utilizing a 30‐place manifold has been developed to study synaptosomal transport; some problems associated with such studies have been identified and clarified. The time course of L‐glutamic acid uptake has been used to test variations in experimental protocol.Synaptosomes apparently become increasingly labile with increased time of incubation. This is indicated by a drop in the curve of uptake vs time after 8–12 min. Ninety seven to 98% of the glutamate taken up from a 10−6m solution is released by osmotic shock.Synaptosomes can be stored in 0.32 m ice‐cold sucrose suspension for periods up to 50 min without decline in measured uptake. Storage for 3 h or more results in a very substantial decline in measured uptake. Neither the decline in measured uptake with time, nor the decline with storage, is prevented by increasing the osmolarity of the solutions used or by use of synaptosomes from the initial 1085 g supemate rather than after sedimentation and resuspension. Although prewarming synaptosomes at 30°C for 20 min prior to their use lessened or eliminated the decline following peak uptake, the difference between stored and non‐stored synaptosomes was not improved. Uptake was also much less when synaptosomes were used from the first supernate or when warmed prior to their use. Storage of tissue prior to homogenization resulted in synaptosomes that gave minimal reductions in measured uptake.Washing synaptosomes after separation from incubation medium resulted in a variable loss of substrate radioactivity, depending on such variables as brand of filter, pore size, composition of wash solution, and temperature of wash solution. The results support the hypothesis that washing causes lysis of a portion of the synaptosomes. However, with Millipore filters (0.45 μm) and a 30°C Krebs‐Henseleit wash solution, the loss caused by washing is minimized (about 15%).Measured uptake is found to depend on the type of filter used. Uptake is much greater with Millipore 0.45 pm filters than with Gelman 0.45 μm filters. Use of Nuclepore (0.4 μm) filters results in measured uptakes only about 5% of that when Millipore 0.45 μm filters are used. With Millipore filters, 0.30 μm pore size filters gave uptakes only 68% of that using 0.45 pm pore size filters.
EFFECTS OF AMMONIUM IONS ON SPONTANEOUS ACTION POTENTIALS AND ON CONTENTS OF SODIUM, POTASSIUM, AMMONIUM AND CHLORIDE IONS IN BRAIN IN VITRO
Authors: Benjamin A. M. , Okamoto K. , Quastel J. H. 
Published: October 2006

Abstract—The effects of ammonium ions on the frequency of spontaneous action potentials in guinea‐pig cerebellar slices, recorded with an extracellular microelectrode, and on the contents of sodium, potassium and chloride ions in incubated guinea‐pig cerebellar, and rat brain cortex, slices have been investigated. The frequencies of the spontaneous action potentials are partially suppressed by concentrations of NH4Cl less than 2 mm and completely abolished by concentrations exceeding 2 mm. The amplitudes of the spike discharges are unaffected. A lag period of at least 15 s precedes the inhibition. The suppressing action of NH on the spike frequency is reversible, as shown by complete recovery on removal of NH after short time intervals. Deficiency of Cl− in the superfusion medium causes conversion of inhibition by NH to excitation. Reduction of [K+], or of [Na+], causes increase of inhibition by NH in a normal [Cl1], and reduction of excitation in a low [Cl1], medium. The inhibitory effects of NH on spike frequency are unaffected by picrotoxin or strychnine. NH4Cl, even at 1 or 2 mm, causes a significant increase of aerobic glycolysis. It is suggested that the lag period preceding the suppression of the frequency of spike discharges by NH is partly due to a metabolic change induced by NH, perhaps a transient lowering of pH in the responsible neurons, causing changed permeability to Cl− and possibly to K+ and Na+, NH promotes, in guinea‐pig cerebellar slices, an inward flow of Na+ and an outward flow of K+, the latter being greater than that due to exchange of K+ for NH. NH4Cl at 1 or 2 mm causes an outward flow of K+ and an inward flow of Cl− in rat brain cortex slices. The movement of Cl− is biphasic, the first phase, seen with low [NH], consisting of an increase of tissue content of Cl− with little or no fluid uptake and a second phase, seen with high (> 5 mm) concentrations of NH, in which the uptake of Cl− is directly proportional to the fluid uptake. It is suggested that the first phase is largely neuronal in location whilst the second is largely glial. In infant rat brain cortex slices, there seems to be predominantly an equal exchange of NH for K+. There is little evidence of energy assisted concentrative uptake of NH by brain slices and this is thought to be due largely to the rapid diffusion of undissociated NH3 across cell membranes. It is suggested that some NH (amounting to about 2 mequiv/1) may be bound in the brain. It is concluded that changes in ionic permeabilities, particularly that of Cl−, partly due to a metabolic action, may be responsible for some of the acute cerebral effects of NH administration.
NEURONAL AND NEUROPIL FRACTIONS FROM DEVELOPING RAT BRAIN
Authors: Sinha A. K. , Rose S. P. R. , Sinha L. , Spears D. 
Published: October 2006

Abstract— A method is described for the preparation of enriched fractions containing isolated neuronal and glial cells from brains derived from 1 to 20‐day‐old rats. The method is based on mechanical disaggregation in a medium containing Ficoll‐PVP followed by centrifugation on a single‐stage two‐step gradient at 13,000g for 30min. The neuronal and neuropil (glial) fractions are approx 70–80% pure in cellular terms.The cells showed well‐preserved cytoplasmic and nuclear morphology at the light and electron microscope level and between 70 and 80% excluded trypan blue. Despite changes in the total cell population with age due to glial proliferation, the proportionate recovery of cells in the separated fractions was fairly constant: based on DNA determination, 23 and 29% of all neurons and 15 and 17% of glia were recovered in the purified fractions from Day 1 and Day 20 animals respectively.Changes in neuronal cell size with age were reflected in a 2.5‐fold increase in protein recovered in the neuronal fraction per mg DNA. Protein and RNA levels/mg DNA in the neuropil fraction reached a maximum at Day 10. It is concluded that the method produces a defined and reliable purification of cells in the separated fractions throughout the studied age range and therefore provides a sound basis for studies on the distribution of biochemical systems between cell types during post‐natal development.
CORRELATION OF PLASMA AND BRAIN AMINO ACID AND PUTATIVE NEUROTRANSMITTER ALTERATIONS DURING ACUTE HEPATIC COMA IN THE RAT
Authors: Mans A. M. , Saunders S. J. , Kirsch R. E. , Biebuyck J. F. 
Published: October 2006

Abstract—During acute hepatic coma following two‐stage hepatic devascularization in the rat, profound changes occurred in plasma and whole‐brain amino acids and putative neurotransmitters. Brain ammonia, glutamine and GABA were increased, aspartate was decreased, while glutamate was unchanged. An increase in brain tryptophan was accompanied by a similar increase in plasma unbound tryptophan but decreased plasma total tryptophan. These changes occurred in the presence of high plasma levels of the other neutral amino acids, including the branched chain amino acids. Plasma insulin was unchanged while glucagon levels rose, resulting in a decreased insulin to glucagon ratio. These results suggest that while plasma unbound tryptophan may influence brain tryptophan levels, altered plasma concentrations of neutral amino acids which compete with tryptophan for transport into the brain do not contribute to the increase in brain tryptophan observed during acute hepatic coma.
Aminophospholipid Asymmetry in Murine Synaptosomal Plasma Membrane
Authors: Fontaine Robert N. , Harris R. Adron , Schroeder Friedhelm 
Published: October 2006

Abstract:The asymmetric distribution of aminophospholipids in isolated murine synaptosomal plasma membranes was determined by a chemical labeling procedure. Under nonpenetrating conditions, mouse brain synaptosomes were reacted with trinitrobenzenesulfonic acid (TNBS) to label outermonolayer aminophospholipids covalently. About 10‐15% of the phosphatidylethanolamine and 20% of the phosphatidylserine were found to be in the outer monolayer of the synaptosomal plasma membrane. Furthermore, the fatty acyl group composition of the labeled phosphatidylethanolamine (outer monolayer) consisted of more saturated fatty acid than did the unlabeled phosphatidylethanolamine (inner monolayer). These results demonstrated an aminophospholipid asymmetry in synaptosomal plasma membranes which was independent of serum‐lipoprotein exchange processes and also of phosphatidylethanolamine‐methylatingenzymes.
Influx of γ‐Aminobutyric Acid and α‐Aminoisobutyric Acid into Mouse Cerebrum Slices Incubated in a Pyruvate Medium with or without Added Glucose or Glucose Analogues Compared with Influx from a Glucose Medium
Authors: Cohen Stephen R. 
Published: October 2006

Abstract:Concentrative influx of γ‐aminobutyric acid (GABA) and α‐aminoisobutyric acid (AIB) into incubated mouse cerebrum slices is decreased when pyruvate is substituted for glucose. Influx of GABA from pyruvate medium is not increased by presence of glucose, 2‐deoxy‐d‐glucose (2‐DOG), or 3‐O‐methyl‐d‐glucose (3‐O‐MeG). Influx of AIB is restored to the rate from glucose medium if 2‐DOG is present initially, but is not restored if 2‐DOG is added with AIB. Influx is not restored if 3‐O‐MeG is present initially, but is restored if 3‐O‐MeG is added with AIB. Influx is restored if glucose is present initially or is added with AIB.