bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF ALUMINUM SALTS ON CULTURED NEUROBLASTOMA CELLS
Authors: Miller Carol A. , Levine E. M. 
Published: October 2006

AbstractExperimental induction of neurofibrillary tangles was demonstrated several years ago in the central nervous system of rabbits injected with aluminum salts. In the current studies, neuroblastoma cells, capable of morphologic and biochemical differentiation in monolayer culture, have been exposed to medium containing aluminum phosphate; such treatment resulted in an abundant accumulation of 100 Å neurofilaments after 6 days of continous exposure to the aluminum salt. While growth rates and incorporation of radioactive thymidine in treated cells remained similar to controls, total cellular protein, and incorporation of radioactive leucine were significantly increased. Paradoxically, when the protein content of aluminum‐treated cultures was maximal, these cultures contained about 20 per cent less ribosomal RNA per cell than in control cultures. In addition, activity of an important neuronal protein, i.e. acetylcholinesterase, was depressed in treated cultures to a level below control values. Both temporal and morphologic similarities between treated neuroblastoma cultures and animals injected with aluminum salts suggest that the observed changes in macromolecular synthesis in cell culture are relevant to in vivo studies.
DEVELOPMENTAL AND REGIONAL VARIATIONS IN NEUROTRANSMITTER‐SENSITIVE ADENYLATE CYCLASE SYSTEMS IN CELL‐FREE PREPARATIONS FROM RAT BRAIN
Authors: Hungen K. Von , Roberts S. , Hill Diane F. 
Published: October 2006

AbstractInvestigations have been carried out on regional and developmental variations in the properties of adenylate cyclase systems in participate preparations from rat brain. EGTA was routinely included in the assay medium to minimize differences in the state of activation of these systems resulting from variations in their exposure to endogenous Ca2+. At birth, adenylate cyclase activity was much higher in the hindbrain‐medullary preparations than in comparable fractions from cerebellum, cerebral cortex or subcortex (including midbrain, corpus striatum, hypothalamus and hippocampus). Adenylate cyclase activity increased during early development in preparations from all areas of the brain. Maximal levels were reached at 14 days of age or later. These levels were not greatly altered in the young adult animal, except in the hindbrain‐medullary area, where a decrease in activity was observed. Adenylate cyclase systems in cerebral cortical and subcortical preparations were activated by norepinephrine and dopamine throughout development. Serotonin also stimulated adenylate cyclase activity in these preparations from young animals but was much less effective in comparable fractions from adult rats. The response to dopamine was diminished with age in cerebral cortical preparations, but not in subcortical fractions. The responses to norepinephrine increased in both brain regions during early development. Adenylate cyclase systems in particulate preparations from the cerebellum and hindbrain‐medullary areas exhibited relatively poor responses to the biogenic amines. Detailed studies of the properties of the cerebral cortical adenylate cyclase systems revealed enhancement of activity by Ca2+ and F− at all stages of development with the maximal activation at 2–3 weeks of age. The results suggest that developmental differences in hormonal sensitivity of adenylate cyclase systems from diverse areas of the brain are related to changes in the proportions of the receptor‐enzyme complexes responsive to the different biogenic amines.
MEASUREMENTS OF RATES OF PROTEIN SYNTHESIS IN RAT BRAIN SLICES
Authors: Dunlop D. S. , Elden W. van , Lajtha A. 
Published: October 2006

AbstractThe use of tracer concentrations of labelled amino acids to measure incorporation in incubated slices of brain results in wide fluctuations with time in the specific activity of the precursor. Using concentrations of about 1 mm of labelled amino acid facilitates the accurate measurement of rates of synthesis. These higher precursor levels in the medium decrease the fluctuations in free amino acid specific activity due to dilution by endogenous amino acid and the production of amino acid by protein degradation, and decrease the lag in incorporation due to transport phenomena. Concentrations of 1 mm amino acid in the medium did not inhibit protein synthesis; with valine, leucine, phenylalanine, lysine and histidine, incorporation rates were similar when measured at trace concentrations and at 1 mm medium levels. The source of amino acid for protein synthesis appears to be intracellular. No evidence could be found for the preferential use of extracellular medium amino acid. The rate of incorporation of amino acids in incubated slices of rat brain was 0.087 per cent of the protein amino acid/h.
INHIBITION OF THE BIOSYNTHESIS OF ISOPRENOID COMPOUNDS BY PHENOLIC ACIDS IN THE RAT BRAIN
Authors: Ranganathan S. , Ramasarma T. 
Published: October 2006

Abstract—The incorporation of [2‐14C]mevalonate into nonsaponifiable lipids by rat brain homogenates is inhibited by phenolic acids derived from tyrosine. The phenyl acids derived from phenylalanine are inhibitory only at very high concentrations compared with phenolic acids. The brain is more sensitive to inhibition by the phenolic acids than the liver. These studies indicate a possible role for phenolic acids in the impairment of cerebral sterol metabolism in phenylketonuria.
UPTAKE OF ACETYLCHOLINE AND CHOLINE INTO RAT BRAIN CORTICAL SLICES AND SYNAPTOSOMES AS RELATED TO 32Pi, INCORPORATION INTO THEIR PHOSPHOLIPIDS
Authors: Widlund L. , Heildronn E. 
Published: October 2006

Abstract—The role of ACh‐stimulated 32Pi incorporation into the phospholipids of rat cerebral cortex slices and isolated nerve endings (synaptosomes) has been studied. ACh stimulation is not connected with any carrier‐mediated uptake of ACh. Such uptake may occur in slices in the presence of the anticholinesterase Sarin but barely in the presence of eserine. Regardless of the nature of the anticholinesterase used, rat cerebral cortex synaptosomes that respire and show high and low affinity choline uptake do not accumulate ACh against a concentration gradient. At exogenous ACh concentrations of 10–5m and above, some ACh enters the synaptosomes by diffusion and significantly stimulates 32Pi incorporation into phosphatidic acid. It is discussed whether, in isolated nerve endings, an increase in cytoplasmic ACh concentration due to diffusion may induce vesicle turnover to keep a balance between ‘free’ and bound ACh or if a presynaptic ACh receptor is responsible for the observed changes in phosphatidic acid. The distribution of accumulated radioactivity derived from exogenous choline and ACh respectively between ACh, choline, phosphorylcholine and betaine has been studied in slices and isolated nerve endings.
DEVELOPMENT OF LIPOGENESIS IN RAT BRAIN CORTEX: THE DIFFERENTIAL INCORPORATION OF GLUCOSE AND ACETATE INTO BRAIN LIPIDS IN VITRO
Authors: Patel M. S. , Tonkonow B. L. 
Published: October 2006

Abstract—The oxidation to CO2 and the incorporation of [U‐14C]glucose and [U‐14C]acetate into lipids by cortex slices from rat brain during the postnatal period were investigated. The oxidation of [U‐14C]glucose was low in 2‐day‐old rat brain, and increased by about two‐fold during the 2nd and 3rd postnatal weeks. The oxidation of [U‐14C]acetate was increased markedly in the second postnatal week, but decreased to rates observed in 2‐day‐old rat brain at the time of weaning. Both labeled substrates were readily incorporated into non‐saponifiable lipids and fatty acids by brain slices from 2‐day‐old rat. Their rates of incorporation and the days on which maximum rates occurred were different, however, maximum incorporation of [U‐14C]glucose and [U‐14]acetate into lipid fractions being observed on about the 7th and 12th postanatal days, respectively. The metabolic compartmentation in the utilization of these substrates for lipogenesis is suggested. The activities of glucose‐6‐phosphate dehydrogenase, cytosolic NADP‐malate dehydrogenase, cytosolic NADP‐isocitrate dehydrogenase, ATP‐citrate lyase and acetyl CoA carboxylase were measured in rat brain during the postnatal period. All enzymes followed somewhat different courses of development; the activity of acetyl CoA carboxylase was, however, the lowest among other key enzymes in the biosynthetic pathway, and its developmental pattern paralleled closely the fatty acid synthesis from [U‐14C]glucose. It is suggested that acetyl CoA carboxylase is a rate‐limiting step in the synthesis de novo of fatty acids in developing rat brain.
PLASMA TRYPTOPHAN AND 5‐HT METABOLISM IN THE CNS OF THE NEWBORN RAT
Authors: Bourgoin S. , Faivre‐Bauman A. , Benda P. , Glowinski J. , Hamon M. 
Published: October 2006

Abstract—The relationships between plasma tryptophan and 5‐HT metabolism in the CNS were studied in newborn rats and compared with adults. Both the concentration of free tryptophan in plasma and that of the amino‐acid in brain were much higher immediately after birth than later on. Drugs such as salicylate and chlordiazepoxide, which increased brain tryptophan concentrations in adults by displacing the plasma amino acid bound to serum albumin, were ineffective in newborn rats: most of the amino acid being already free in their plasma. The study of 5‐HT metabolism in brain stem slices revealed that the affinity of the uptake process for tryptophan was higher in newborn than in adult animals, whereas the reverse situation was observed for the enzyme complex involved in 5‐HT synthesis (lower apparent Km in adults). In addition, the catabolism of newly synthesized 5‐HT was more rapid in newborn than in adult tissues. Finally, the free state of tryptophan in plasma of newborn animals induced in brain both a high amino acid concentration and, in contrast to the situation observed in adults, a synthesis rate of 5‐HT very near its maximal value.
EFFECTS OF 5‐HYDROXYTRYPTOPHAN ON SEROTONIN IN NERVE ENDINGS1
Authors: McBride W. J. , Aprison M. H. , Hingtgen J. N. 
Published: October 2006

Abstract—Preparations of synaptosomes (P2) from the telencephalon and from the diencephalon plus optic lobes of the pigeon and from the telencephalon of the rat were used to study the effects of 5‐hydroxytryptophan (5‐HTP) on (a) the levels of serotonin (5‐HT) in nerve endings and (b) the release of 5‐HT from nerve endings. The levels of 5‐HT were significantly higher (3.21 × 0.35 nmol/g original tissue weight) in the P2 fraction isolated from the telencephalon of pigeons given intramuscular injections of 50mg/kg of d,l‐5‐HTP in comparison to control values (1.42 ± 0.07). A similar twofold increase was observed with the P2 fraction isolated from the diencephalon plus optic lobes. In addition, the levels of 5‐HTP and 5‐hydroxyindoleacetic acid also increased significantly in these P2 fractions isolated from pigeons given d,l‐5‐HTP injections in comparison to values obtained for pigeons given saline injections. In vitro studies using preparations of synaptosomes (from both pigeon and rat) labelled with [3H]5‐HT indicated that 0.10 mil l‐5‐HTP increased the release of [3H]5‐HT twofold over control values. A concentration as low as 0.001 mm l‐5‐HTP was tested on the P2 fraction from the telencephalon of the pigeon and was found to significantly increase the release of [3H]5‐HT over control values. This effect by l‐5‐HTP was blocked if a decarboxylase inhibitor was added to the medium. l‐5‐HTP at a concentration of 1.5 mm had no apparent effect on the release of [3H]norepinephrine or [3H]dopamine from synaptosomes prepared from the telencephalon of the rat or pigeon. The results are discussed in terms of the role of serotonin in producing certain types of behavioral depressions exhibited by pigeons and rats given injections of 5‐HTP.
SOME PROPERTIES OF GUINEA PIG BRAIN GLUTAMATE DECARBOXYLASE AND ITS INHIBITION BY THE CONVULSANT ALLYLGLYCINE (2‐AMINO‐4‐PENTENOIC ACID)1
Authors: Fisher S. K. , Davies W. E. 
Published: October 2006

Abstract—Glutamate decarboxylase (l‐glutamate 1‐carboxy‐lyase EC 4.1.1.15; GAD) has been isolated from guinea pig brain and some of its properties studied. Many of its properties indicated that it was similar if not identical to the decarboxylase isolated from other species. It showed normal Michaelis‐Menten kinetics (Km= 8 mM), had a pH optimum of 6.6–7.0 and was protected by sulphydryl reagents. Its activity was stimulated by pyridoxal phosphate and inhibited by a variety of anions, cations and carbonyl trapping agents. Allylglycine strongly inhibited GAD isolated from the brains of several different species. The mechanism of this inhibition has been studied kinetically and compared to chloride induced inhibition. The kinetic data presented is consistent with the idea that allylglycine inhibits the enzyme by a partially reversible inactivation rather than by reversible competitive inhibition.
RETROGRADE AXONAL TRANSPORT OF RAPIDLY MIGRATING PROTEINS IN THE VAGUS AND HYPOGLOSSAL NERVES OF THE RABBIT
Authors: Frizell M. , Sjöstrand J. 
Published: October 2006

Abstract—The redistribution of rapidly migrating [3H]leucine‐labelled proteins was studied using double ligatures applied to the vagus nerve and single ligatures, applied to the hypoglossal nerves. Rapidly migrating proteins accumulating for 16 h proximal to a distal ligature of the cervical vagus redistributed to give a retrograde accumulation distal to a second ligature. Within 6 h a substantial redistribution occurred indicating a rapid retrograde transport. After 21 h there was a further accumulation with 70 per cent of the labelled material accumulating at the distal end of the isolated nerve segment and 16 per cent accumulating at the proximal end. It was shown that about a half of the retrograde accumulation was dependent on the distal accumulation zone. Rapidly migrating proteins accumulated distal to a ligature applied to the hypoglossal nerve 16 h after labelling of the nerve cell bodies indicating that a rapid retrograde transport of labelled macromolecules occurs from the peripheral parts of the nerve in the tongue. Labelled proteins accumulated proximal to ligatures and transections of both the hypoglossal and vagus nerve when applied 16 h after labelling of the nerve cell bodies, indicating the presence of axonal proteins, migrating at a rate of transport intermediate to that of rapidly and slowly migrating proteins.
ACTIVATION, INHIBITION AND AGGREGATION OF CHOLINE ACETYLTRANSFERASE (EC 2.3.1.6)
Authors: Chao L.‐P. , Wolfgram F. 
Published: October 2006

Abstract—Mercuric chloride, silver acetate and cupric sulphate (0·1 mm) completely inhibited purified choline acetyltransferase from bovine caudate nuclei. At the same concentration cadmium chloride and zinc acetate gave a 50 per cent inhibition. Potassium and sodium salts more than doubled the enzymatic activity while creatinine hydrochloride more than tripled it. Guanidine hydrochloride was less effective than creatinine hydrochloride but more effective than KCl and NaCl. Sodium chloride and creatinine hydrochloride had a synergistic effect on the enzyme.When ammonium sulphate was used to fractionate the choline acetyltransferase that had been extracted from bovine caudate nuclei, the enzyme aggregated into different molecular sizes as determined by exclusion chromatography on Bio‐gel A‐1·5 m. The molecular weight of the largest aggregate was at least 106 daltons. The initial tissue extract contained only one molecular species of ChAc as did a partially purified preparation in which ammonium sulphate was not used in the purification.
A STUDY OF SELECTED CATECHOLAMINE METABOLIZING ENZYMES: A COMPARISON OF DEPRESSIVE SUICIDES AND ALCOHOLIC SUICIDES WITH CONTROLS1
Authors: Grote S. S. , Moses S. G. , Robins E. , Hudgens R. W. , Croninger A. B. 
Published: October 2006

Abstract—The regional distributions of monamine oxidase (MAO) (EC 1.4.3.4), catechol‐O‐methyltransferase (COMT) (EC 2.1.1.6), tyrosine hydroxylase (TH) (EC 1.14.3.2), and dopamine‐β‐hydroxylase (DBH) (EC 1.14.2.1) have been examined in human brains obtained at autopsy from persons who died of natural causes (controls), and from persons who committed suicide and were further categorized as suffering from affective disorder (depression) or from alcoholism. Post mortem animal studies showed no changes in MAO or COMT activities in rabbit brain or in DBH activity in rat brain when the intact bodies were left at room temperature up to 24 h. TH activity in rabbit brains, however, began to decline immediately after death and after 24 h at room temperature it was approximately 48 per cent of the fresh brain level. There was no significant variation in activity of COMT, TH and DBH in human brain attributable to age or sex. MAO activities in the 60–70 yr decade were 34 per cent higher than in the 30–40 yr decade. MAO activities were highest in the hypothalamus and substantia nigra, TH activities were highest in substantia nigra, putamen and head of caudate, and DBH activities were greatest in tegmentum of pons and hypothalamus. Only minimal regional differences in COMT activities were observed. No significant differences were found between enzyme activities in brain areas of controls and suicides with the possible exception of TH in the substantia nigra, where the depressive suicides (but not the alcoholics) showed greater activity (P < 0·02). These findings appear not to support the catecholamine hypothesis of affective disorder.
ENZYMATIC SULPHATION OF SOME GALACTOSE‐CONTAINING SPHINGOLIPIDS IN DEVELOPING RAT BRAIN1
Authors: Farrell D. F. 
Published: October 2006

Abstract— Cerebroside sulphotransferase has been found to catalyze the transfer of sulphate from 3′‐phosphoadenosine‐5′‐phosphosulfate (PAPS) to both the α‐hydroxy fatty acid galactosylceramides and the nonhydroxy fatty acid galactosylceramides. The sulphotransferase has a higher affinity for the α‐hydroxy fatty acid galactosylceramides than for the nonhydroxy fatty acid galactosylceramides and will also use lactosylceramide as an acceptor for the transfer of sulphate from PAPS.A second sulphotransferase, PAPS: psychosine sulphotransferase, is also present in the developing rat brain and will catalyse the transfer of sulphate from PAPS to galactosylsphingosine and lactosylsphingosine. The sulphate moiety was determined to be on the galactose and most likely on the 3′ position giving a proposed structure of: 3‐O‐SO4‐galactosylsphingosine. The possible role of this later pathway in the synthesis of sulphogaiactosylceramide remains to be elucidated.
ACID HYDROLASES AND OTHER ENZYMES IN SECONDARY DEMYELINATION: A QUANTITATIVE HISTOCHEMICAL STUDY IN THE WOBBLER MOUSE1
Authors: Hirsch Hilde E. , Andrews J. M. , Parks Mary Ellen 
Published: October 2006

Abstract— The hereditary motor neuron degeneration found in the wobbler (wr) mouse was studied as a model of secondary demyelination. Lysosomal enzymes (acid phosphatase, acid proteinase, β‐glucuronidase and β‐galactosidase) were found elevated about three‐fold in the white matter of the affected cervical spinal cord as compared with normal controls; but they were either not increased, or increased much less, in the anterior horn. Since gliosis and influx of phagocytic cells are minimal in this model, the high hydrolase levels are believed to arise primarily from (a) the accumulations of axonal dense bodies seen in involved areas, and (b) from indigenous cells engaged in breaking down the myelin fragments. Thus, secondary demyelination may, at least in this case, be initiated by enzymes of local origin.DNA levels per unit weight of tissue in both white and gray matter of wobbler cervical cord were elevated 40‐50 per cent over controls. However, this was considered to reflect the stunted growth of wobbler mice rather than proliferation or influx of cells (an altered ratio of DNA to protein was demonstrated in the brain).Wobbler mice had similar levels of lactic dehydrogenase as controls; glucose‐6‐phosphate dehydrogenase was moderately elevated, and glycerol‐3‐phosphate dehydrogenase was less active in the anterior horn but more active in the white matter of the spinal cord.
UBIQUINONE REDOX STATUS IN BRAIN IN VITRO
Authors: Klicpera J. A. , Hoffmann P. C. 
Published: October 2006

Abstract—The redox status of ubiquinone (Q) as an index of mitochondrial respiratory chain activity in chopped telencephalon from the rat was investigated. With 12mm‐glucose under aerobic conditions Q was 73% oxidized. Three mm‐amytal and 2 μm‐rotenone, inhibitors of mitochondrial NADH oxidation, resulted in Q being further oxidized by 14 and 16%, respectively. Thus, amytal and rotenone result in shifts in Q redox status of rat telencephalon slices in accord with the known site of action of these compounds in isolated mitochondria. However, under anaerobic conditions Q redox status shifted to 25% oxidized while incubation with 1 mm‐NaCN resulted in a shift to only 58% oxidized. This discrepancy may result from concomitant inhibition in the supply of reducing equivalents to Q from substrate by NaCN or it may reflect a differential sensitivity of neuronal and glial mitochondria to NaCN. Evaluation of Q oxidation‐reduction can be used to measure the effects of drugs and physiological perturbations on the redox status of the mitochondrial compartment of intact brain preparations.
A ROLE FOR DIVALENT CATIONS IN THE UPTAKE OF NORADRENALINE BY SYNAPTOSOMES
Authors: White T. D. 
Published: October 2006

Abstract–The effects of divalent cations on the initial rates of noradrenaline uptake by synaptosomes were determined using Millipore filtration to terminate the reaction. The removal of either Ca2+ or Mg2+ from the incubation medium had no effect on uptake, but when both Ca2+ and Mg2+ were removed, uptake was reduced. Uptake was also diminished when Ca2+ was absent and 1 mm‐EGTA added to the medium. It appeared that Ca2+ was required for optimal uptake but that Mg2+ could partially substitute for Ca2+ in this regard. The reduction in the rate of uptake when both Ca2+0 and Mg2+ were absent could be rapidly and completely reversed by restoring Ca2+, Mg2+, or both Ca2+ and Mg2+ to the incubation medium. Of the divalent cations tested, Ca2+ and Mg2+, but not Mn2+, supported noradrenaline uptake. When the kinetics of uptake were examined, it was found that removing both Ca2+ and Mg2+ from the medium resulted in a reduction of the Vmax for noradrenaline uptake. It is apparent from these results that, in addition to facilitating the release of noradrenaline from noradrenergic terminals, Ca2+ may also play a role in the uptake of noradrenaline by presynaptic nerve‐endings in the CNS.
RELEASE AND EXCHANGE STUDIES RELATING TO THE SYNAPTOSOMAL UPTAKE OF GABA
Authors: Raiteri M. , Federico R. , Coletti A. , Levi G. 
Published: October 2006

Abstract— Synaptosomal release and exchange of [3H]GABA were studied by a superfusion technique which minimizes reuptake. The release of [3H]GABA was increased by depolarizing concentrations of KCl and showed calcium‐dependence. Superfusion with 1‐1000 μm unlabelled GABA caused a dose dependent, saturable increase in the release of radioactivity by homoexchange. The exchange process showed high substrate specificity: among the various amino acids and putative neurotransmitters tested, only γ‐amino‐β‐hydroxybutyric acid was a good stimulator of [3H]GABA release. Superfusion with sodium‐free medium (NaCl replaced by sucrose) virtually abolished homoexchange. Ouabain also increased the release of [3H]GABA, and its action was additive to that of unlabelled GABA.The presence of exchange at concentrations that are in the range of the high affinity uptake system, the apparent similarity between calculated rates of exchange and initial uptake rates, the non‐detectability of exchange in a condition (Na+ deprivation) which inhibits high affinity uptake, and the lack of decrease of actual GABA concentration in incubation media used for uptake experiments, all suggest that homoexchange accounts for a substantial part of the synaptosomal accumulation of [3H]GABA generally interpreted as high affinity uptake.