bluuebunny/crossref_metadata_2025_split huggingface dataset:
CYCLIC AMP AND PHOSPHODIESTERASE IN SYNAPTIC VESICLES FROM MOUSE BRAIN
Authors: Johnson G. A. , Boukma Sally J. , Lahti R. A. , Mathews J. 
Published: October 2006

AbstractThe isolation of synaptic vesicles from mouse brain by a modification of previously reported methodology is described. Homogeneity of the preparations was ascertained by electron microscopy. Vesicles thus isolated contained cyclic AMP (365 ± 44 pmol/mg of protein; mean ± S.E.M.) and adenosine 3′,5′‐monophosphate phosphodiesterase activity (500 pmol/mg of protein per 30 min). The number of vesicles in three of the vesicle preparations was determined by a visual count of grid fields under the electron microscope. The content of cyclic AMP in the vesicles was calculated at 5000‐7500 molecules/vesiclc. The presence of cyclic AMP in the synaptic vesicles from presynaptic nerve endings would support a role for this nucleotide in nerve transmission.
INTERVENTION OF BRAIN CORTEX PHOSPHOLIPIDS IN PYRIDOXAL PHOSPHATE‐DEPENDENT REACTIONS
Authors: Maniero G. , Toffano G. , Vecchia P. , Orlando P. 
Published: October 2006

AbstractWe have examined the role of brain cortex phospholipids in regulating some enzymic reactions specific to the CNS. The study was carried out at the level of the reactions concerned with GABA formation, both in vivo and in vitro, and included investigation of the specificity of the effect. It was found that the brain cortex phospholipids enhance the transformation of exogenous vitamin B6 into pyridoxal‐5‐phosphate by activating the pyridoxal 5‐phosphate‐kinase enzyme, in contrast to other phospholipids of different origins. The possible role of brain cortex phospholipids in regulating an enzyme contained in the soluble fraction is discussed. Moreover, it is suggested that the specific effect of the phospholipids from various sources is linked to their fatty acid composition and to be therefore dependent on the aliphatic chains.
CATION UPTAKE BY INTACT NUCLEI FROM RAT CEREBRAL CORTEX
Authors: Haljamäe H. , Waldman A. A. 
Published: October 2006

AbstractA method is described for determining the uptake of cations by intact nuclei from rat cerebral cortex. The divalent cations of magnesium, manganese and calcium were found to be concentrated in the nuclear pellet to levels well above the initial concentration of the medium, whereas little uptake of either potassium or sodium was observed. The binding of divalent cations to the nuclei will produce a cationic environment quite different from that of the external medium. Such localized differences may play a role in the control of nuclear activities.
ALTERATIONS IN NINHYDRIN‐POSITIVE SUBSTANCES AND CYTOPLASMIC PROTEIN SYNTHESIS IN THE BRAINS OF ASCORBIC ACID‐DEFICIENT GUINEA PIGS1
Authors: Enwonwu C. O. 
Published: October 2006

AbstractNewly‐weaned male guinea pigs were fed an ascorbic acid‐deficient diet ad libitum and compared with control animals pair‐fed an adequate diet for a similar duration. The ascorbic acid‐deficient animals demonstrated prominent elevations in serum concentrations of tyrosine (+427%), phenylalanine (+36%) and arginine (+21 %) with concomitant depressions in levels of glycine (–57 %), histidine (–39 %), ethanolamine (–38%) and glutamic acid (–22 %). With few exceptions, the alterations in the liver amino acid profiles were in the same directions as those observed in the serum. The scorbutic brains showed 28–36 per cent of the retention of total ascorbic acid found in control animals and were characterized by marked elevation (+83%) in tyrosine content, hardly any alteration in phenylalanine (–9%), and depressed levels of histidine (–33 %), arginine (–25%), phosphoserine (–50%) and GABA (–12%). The implications of such abnormal changes in free amino acid patterns were evaluated in the light of the role of some of these amino acids as precursors for the synthesis of neuroregulatory substances. No difference was observed in the brain polysomal profiles as isolated from the two groups of animals. Incubation of polysomes from ascorbic acid‐deficient brains with autologous pH 5 enzyme derived from cell sap not passed through Sephadex G‐25 revealed low uptake of [14C]phenylalanine in comparison to that for a similar system from control animals. Use of pH 5 enzymes prepared from Sephadex‐treated and dialysed cell saps eliminated the difference in specific activities of the two groups of ribosomes, an observation suggesting that ascorbic acid deficiency either intensified the activity of the inhibitory components or reduced the low molecular weight stimulatory substances present under normal conditions in the brain postmicrosomal fraction.
ENZYMATIC REGULATION OF ADENOSINE 3′,5′‐MONOPHOSPHATE (CYCLIC AMP) IN THE FREEZING EPILEPTOGENIC LESION OF RAT BRAIN AND IN HOMOLOGOUS CONTRALATERAL CORTEX
Authors: Walker J. E. , Lewin E. , Sheppard J. R. , Cromwell R. 
Published: October 2006

AbstractFreezing epileptogenic lesions were made unilaterally in rat cerebral cortex. Such lesions were associated with an increase in adenyl cyclase activity and a decrease in the membrane‐associated phosphodiesterase activity, with a concomitant increase in the level of cyclic AMP. Similar, though less striking, changes occurred in homologous contralateral cortex (‘mirror focus’). The effects of cyclic AMP on brain membrane systems are discussed, with the suggestion that this substance may play an important role in the genesis of focal seizures.
PATTERN OF RNA SYNTHESIS IN THE SCIATIC NERVE OF THE HEN DURING WALLERIAN DEGENERATION
Authors: Muirhead P. D. , Mezei Catherine 
Published: October 2006

AbstractThe pattern of synthesis of rapidly‐labelled RNA of hen sciatic nerve was studied during Wallerian degeneration. At 2,4,8, 16 and 30 days of degeneration the proximal and distal stumps of the severed nerve as well as the intact contralateral sciatic nerve (functional control) were excised and incubated with either [5‐3H]uridine or [2‐14C]uridine for 0.5 h. The electrophoretic pattern of RNA from the normal adult sciatic nerve showed that most of the radioactivity was incorporated into RNA species migrating between the 18 S and 4 S components of the bulk RNA. The synthesis of RNA was sensitive to actinomycin‐D, an indication that it was directed by a DNA template. The electrophoretic patterns of the rapidly‐labelled RNA in the proximal and distal nerve stumps demonstrated a change following nerve section. After 2–4 days of Wallerian degeneration the degenerating distal nerves incorporated more radioactivity in the 4 S region than the corresponding controls, but at 8 and 16‐days after degeneration relatively more label appeared in higher molecular weight RNA species. In the intact sciatic nerve of the operated hens progressively more radioactivity was detected in the 4 S region with increasing time after the contralateral nerve section. At each stage of Wallerian degeneration the specific radioactivities of RNA in the control nerves from experimental hens were higher than those of the normal adult sciatic nerve. These results indicated a change of RNA metabolism in increased functional activity and during Wallerian degeneration.
THE EFFECT OF LIMB ISCHAEMIA ON THE TURNOVER OF NORADRENALINE IN THE HYPOTHALAMUS AND BRAIN STEM OF THE RAT
Authors: Stoner H. B. , Elson Patricia M. , Koltay Edit 
Published: October 2006

AbstractThe effect of ischaemic limb injury on the turnover of noradrenaline in the hypothalamus and brain stem has been studied in rats. There are theoretical reasons for thinking that these regions are activated in trauma and previous work showed that during limb‐ischaemia the concentration of noradrenaline in the hypothalamus decreased by 27 per cent. The tourniquets were applied to both hind‐limbs 1 h after the injection of [14C]‐tyrosine when the labelling of the noradrenaline was maximal.During 4 h limb ischaemia the endogenous tyrosine concentration in the plasma decreased while that in the hypothalamus first rose and then fell. Changes in a similar direction in the brain stem were not statistically significant. Limb ischaemia did not affect the decline in the specific activity of the plasma or tissue tyrosine. It was concluded that the injury increased the utilization of tyrosine by the body.During the 4 h bilateral hind‐limb ischaemia the rate of decline of [14C]noradrenaline was significantly increased in the brain stem but not in the hypothalamus. Conditions in the brain stem were sufficiently close to ‘steady‐state’ to be able to conclude that the injury increased the metabolism of noradrenaline in the brain stem. Conditions in the hypothalamus were too complicated for definite conclusions to be drawn. The possible reasons for this and the limitations of this method for studying noradrenaline turnover are discussed.
Inorganic ion effects on the kinetic parameters of acetylcholinesterase
Authors: Dawson R. M. , Crone H. D. 
Published: October 2006

AbstractEARLY work on the effects of inorganic ions on the activity of acetylcholine acetyl‐hydrolase (EC 3.1.1.7; AChE) from various sources has been summarized by COHEN and OOSTERBAAN (1963) and many other reports have been published subsequently (CHANGEUX, 1966; CRONE, 1973; HELLER and HANAHAN, 1972; IVANOVA, 1967; KITZ, BRASWELL and GINSBURG, 1970; ROUF‐CALIS and QUIST, 1972; ROUFOGALIS and THOMAS, 1968; WINS, SCHOFFENIELS and FOIDART, 1970). Despite this work, no comprehensive study has yet been made to determine whether the observed effects are specific to particular ions or dependent only on the ionic strength of the medium (CHANGEUX, 1966). In some cases, specific ion effects have been observed (CHANGEUX, 1966; HELLER and HANAHAN, 1972; ROUFOGALIS and QUIST, 1972; ROUFOGALIS and THOMAS, 1968) at salt concentrations from 600 mM to below 1 mM, but the studies were not detailed enough and in some cases the total ionic strength was not rigidly controlled, so that no general deductions can be drawn.We have studied the hydrolysis of acetylcholine (ACh) by bovine erythrocyte AChE at subinhibitory substrate concentrations, and now present our results on the effect of inorganic salts at varying ionic strength on the kinetic parameters Km, and Vmax. The present work shows that this hydrolysis follows simple Michaelis kinetics very closely, and therefore these two constants suffice to define the complete pattern of initial reaction velocity as a function of substrate concentration (ATKINSON, 1966).
THE QUANTITATIVE HISTOCHEMISTRY OF ACID PROTEINASE IN THE NERVOUS SYSTEM: LOCALIZATION IN NEURONS1
Authors: Hirsch Hilde E. , Parks Mary Ellen 
Published: October 2006

AbstractA new, fluorometric method was used to assay acid proteinase in tissue samples at great sensitivity. Digestion of hemoglobin at pH 3.8 (in brain mostly due to cathepsin D) was measured in individual nerve cell bodies and neuropil from the anterior horn of the spinal cord, and in the molecular and granular layers and while matter of cerebellum, in man and in monkey. Anterior horn cell perikarya were about 25 times more active than neuropil, and the granular layer of cerebellum had about three times the activity of the molecular layer. This predominantly neuronal localization resembles the distribution of other lysosomal hydrolases. The high capacity for protein breakdown found in neurons is in accord with their known high rates of protein synthesis and turnover.
SUBCELLULAR LOCALIZATION OF NEWLY‐FORMED [3H]ACETYLCHOLINE IN RAT CEREBRAL CORTEX IN VITRO
Authors: Molenaar P. C. , Polak R. L. , Nickolson V. J. 
Published: October 2006

Abstract—Slices from rat brain cortex were incubated for either 5 or 60 min in a medium containing [3H]choline and 4·7 or 25 mm‐KCl. Bioassayable ACh and labelled ACh were determined in the incubation medium, in the total tissue homogenate and in subcellular fractions. Raising the KCl concentration from 4·7 to 25 mm stimulated the release and synthesis of total and of labelled ACh. In medium containing 25 mm‐KCl the amounts of ACh decreased in the tissue and in the nerve ending cytoplasm, but remained constant in the synaptic vesicles. After incubation in 25 mm‐KCl medium the ACh in the vesicles was labelled to the same extent as the cytoplasmic ACh but after incubation in 4·7 mm‐KCl medium vesicular ACh was labelled less than cytoplasmic ACh. During 5 min incubation in medium containing 25 mm‐KCl the ratio of labelled to total ACh was much higher in the medium than in the homogenate, the vesicles or the cytoplasm. During the last 15 min of the 60 min incubation the ratio of labelled to total ACh in the medium was still higher than that in the tissue fractions, but less so than during the 5 min incubation. It is concluded that the vesicular and cytoplasmic fractions are not identical with the store in the tissue from which newly‐synthesized ACh is preferentially released.
SIMULTANEOUS INCORPORATION OF ORALLY ADMINISTERED [9, 10‐3H2]OLEIC AND [1‐14C]LINOLEIC ACIDS INTO LIPIDS OF THE ADULT RAT BRAIN
Authors: Illingworth D. R. , Glover J. 
Published: October 2006

Abstract—The incorporation of an orally administered mixture of [9,10‐3H2joleic acid and [1‐14C]linoleic acid into the brain and spinal cord lipids was maximal after 24 h compared with 4 h for extraneural tissue. In the latter, both acids were utilized equally well for triglyceride biosynthesis, but linoleate entered phosphatidylcholine more rapidly than oleate. Oleic acid was preferentially incorporated into newly synthesized cholesterol esters although 4 h after dosing most cholesterol esters present in serum were formed preferentially from linoleate presumably by the action of lecithin‐cholesterol acyl transferase.In neural tissue, a considerable amount of [1‐14C]linoleate was metabolized to higher polyunsaturated fatty acids, whereas in the case of oleate, 90 per cent of the tritium activity remained in monoenic acids at all time periods studied. Both acids were initially incorporated most rapidly into the lecithin fraction of brain and spinal cord, but after 7 days diacyl phosphatidylethanolamine had the highest specific activity.These data are consistent with the view that the uptake of labelled fatty acids by the brain takes place principally as free acids but that some uptake of esterified forms, probably largely as phosphatidylcholine, also occurs. The low linoleate content of the brain and probably also of cerebrospinal fluid cannot be explained on the basis of a selective restriction on the uptake of this lipid from plasma.
THE EFFECT OF AGEING ON RNA/DNA RATIOS IN BRAIN REGIONS OF THE C57BL/6J MALE MOUSE
Authors: Chaconas G. , Finch C. E. 
Published: October 2006

Abstract—The effect of ageing on RNA/DNA was investigated in brain regions and liver of a healthy subpopulation of C57BL/6J male mice. A decrease of 10% in RNA/DNA was found in senescent striatum in contrast to absence of significant change in the hypothalamus, cerebellum, hippocampus, septum and liver.
ISOLATION OF AN ACID‐SOLUBLE BASIC PROTEIN FROM MONKEY BRAIN
Authors: Wedege Elisabeth 
Published: October 2006

Abstract—A basic protein, soluble in 0·1 m‐perchloric acid, has been purified from brain of Macaca irus. The protein is homogeneous as indicated by ultracentrifugation, gel filtration, gel isoelectric focusing and gel electrophoresis at pH 2·9, 4·3 and 7·5. The molecular weight is estimated to be 16,000 by electrophoresis in sodium dodecyl sulphate–polyacrylamide gels. This result is in agreement with the value of 16,728 obtained from the amino acid analysis. The protein dimerizes under alkaline conditions. The predominant amino acid is glycine (15%) and the protein also contains 4% cysteine. The ratio of acidic to basic amino acids is 1·6, but a high amide content gives the protein a basic character. An isoelectric point of 9·5 is observed in gel isoelectric focusing.
ZUR ENERGIEBEDÜRFTIGEN Ca2+‐AKKUMULATION IN MITOCHONDRIEN AUS RATTENHIRN
Authors: Böhme G. , Lutze G. , Pollak K.‐H. , Winter O. , Thews J. , Kassebaum I. 
Published: October 2006

Abstract—(1) The properties of a preparation of functional intact rat brain mitochondria are described and the resulting fraction is enzymatically characterized.(2) These mitochondria are able to accumulate Ca2+ in a respiration‐dependent reaction without additions of Pi and/or adenine nucleotides.(3) As criteria the increased acidity of the incubation medium accompanying the energy‐dependent Ca2+ accumulation, its inhibition by rotenon and Antimycin A, the acceleration of respiration and the redox change of the pyridine nucleotides were recorded and Ca2+ accumulation by the mitochondria was determined by complexemetric methods.(4) The maximum Ca2+ accumulation by rat brain mitochondria amounts to only 25 per cent of that by rat liver mitochondria under similar conditions (on the base per mg protein); after addition of 1 mm‐ADP (without Pi) the comparable value was about 50 per cent.
TYROSINE HYDROXYLASE OF SHEEP BRAIN: SOME CATALYTIC AND CHEMICAL PROPERTIES OF THE DETERGENT‐SOLUBILIZED, PARTIALLY PURIFIED ENZYME1
Authors: Poillon W. N. 
Published: October 2006

Abstract– Detergent‐solubilized tyrosine hydroxylase from the caudate nucleus of the sheep was purified 3‐fold by affinity chromatography on 3‐iodotyrosine modified agarose. Supplementation of the standard assay with 1 mM Fe2+ resulted in only slight stimulation of the enzymic activity. The enzyme was, however, markedly inhibited by certain complexing agents specific for either Fe2+ or Fe3+. Double reciprocal plots of the kinetic data for a representative complexing agent, bathophenanthroline, showed the inhibition to be competitive with O2 (apparent Km 0.15 mM) and noncompetitive with either l‐tyrosine or the synthetic tetrahydropterin cofactor DMPH4 (apparent Km's 0.12 and 0.29 mM, respectively). The combined inhibition and kinetics studies strongly suggest that brain tyrosine hydroxylase is an iron enzyme. Furthermore, the prosthetic iron very likely participates directly in catalytic function, presumably by binding molecular oxygen.The activity of ammonium sulphate‐precipitated enzyme was found to be stimulated 2‐fold by Fe2+, catalase or peroxidase, while untreated enzyme was markedly less affected by these agents. Since the only ostensible difference between the two preparations was the extensive aggregation present in the former case, the change in physical state evoked by ammonium sulphate precipitation appeared to be somehow related to this peculiar property of the enzyme.
EFFECTS OF ATP ON THE ACTIVITY OF NUCLEOSIDE 3′,5′‐CYCLIC MONOPHOSPHATE PHOSPHODIESTERASE FROM BRAIN
Authors: Teshima Y. , Yamazaki R. , Kakiuchi S. 
Published: October 2006

AbstractATP is known to inhibit the phosphodiesterase activity in the supernatant fraction of the brain homogenate. Results showed that, when enzyme activity was assayed by determining the change in the concentration of substrate, the magnitude of the inhibition by 2 ∼ 3 mm‐ATP was not more than 20% and this effect of ATP can be explained mainly, if not entirely, on the basis of chelation of ATP with Mg2+ and Ca2+in vitro, both of which are necessary for enzyme activity. When brain phosphodiesterase was assayed by measuring 5′‐AMP (product), the effect of ATP was erroneously exaggerated. This is due to ATP‐dependent conversion of 5′‐AMP to inosinic acid catalysed by adenylate deaminase in the crude preparation.
EFFECT OF INCREASED RAT BRAIN TRYPTOPHAN ON 5‐HYDROXYTRYPTAMINE AND 5‐HYDROXYINDOLYL ACETIC ACID IN THE HYPOTHALAMUS AND OTHER BRAIN REGIONS
Authors: Knott P. J. , Curzon G. 
Published: October 2006

Abstract—Tryptophan was found at higher concentration in the rat hypothalamus than in other brain regions. This difference was explicable neither by regional differences in blood content nor by differences in tryptophan recovery from different weights of tissue. It was not due to interference by other known brain indoles. After food deprivation or tryptophan injection the tryptophan concentration rose in all regions. Total 5‐hydroxyindole increases showed regional differences but relative changes were similar after both procedures. Increases in 5‐hydroxytryptamine were clearest in midbrain + hippocampus. In general, 5‐hydroxyindolylacetic acid increased more markedly than 5‐hydroxytryptamine. The hypothalamus appeared refractory with negligible increases of both 5‐hydroxyindoles upon either food deprivation or tryptophan administration even though hypothalamic tryptophan concentration rose considerably. Results are discussed in relation to other evidence suggesting special characteristics of 5‐HT regulation in the hypothalamus.
THE CATION SENSITIVITY OF THE ACETYLCHOLINE RECEPTOR FROM TORPEDO CALIFORNICA
Authors: Schmidt J. , Raftery M. A. 
Published: October 2006

Abstract—The effects of various cations and cholinergic ligands on the rate of α‐bungarotoxin‐acetylcholine receptor complex formation has been studied by means of a DEAE‐cellulose disk assay technique. The reaction rate is reduced to one half the initial rate in the presence of 2·5 · 10−6m acetyleholine. a value close to the observed KD of ACh measured by equilibrium dialysis. Inhibition constants of about 5 mM were obtained for most monovalent cations whereas divalent cations gave inhibition constants of 0·05‐0·2 mm. The rate and extent of toxin‐receptor complex formation was also investigated as a function of hydrogen ion concentration; the rate of formation reaches a maximum at pH 7·5 and a group with a pK about 6 inhibits toxin binding to the receptor when protonated.These data can be correlated with the observed effects of inorganic cations on the binding of cholinergic ligands in vivo at the neuromuscular junction. Given the affinities of the individual cations, it is possible to predict how the apparent affinity of a cation‐sensitive cholinergic ligand will change with variations of buffer composition.
ANABOLIC RESPONSES OF EMBRYONIC DORSAL ROOT GANGLIA TO NERVE GROWTH FACTOR, INSULIN, CONCANAVALIN A OR SERUM IN VITRO
Authors: Burnham Patricia A. , Silva J. A. , Varon S. 
Published: October 2006

Abstract—Intact and dissociated dorsal root ganglia from 8‐day chick embryos were examined for their ability to incorporate radio‐precursors into RNA and protein in unsupplemented medium or in medium supplemented with Nerve Growth Factor, insulin, Concanavalin A, fetal calf serum, or several combinations of such agents. In the absence of any agent, incorporation into RNA and protein declined with time. All four agents maintained or improved the initial incorporation rates, and optimal doses were determined in each case. Different combinations of two agents led to potentiated, full or partially additive, or inhibited effects; in particular, NGF promoted incorporation even in conjunction with insulin (additive) or serum (potentiating). Several differences were noted between the responses of intact and of dissociated ganglia.
PHOSPHOLIPID METABOLISM IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS: ACTIVITY OF BRAIN PHOSPHOLIPASE A1, TOWARDS SPECIFICALLY LABELLED GLYCEROPHOSPHOLIPIDS
Authors: Woelk H. , Kanig K. 
Published: October 2006

Abstract—The activity of phospholipase A1 (phosphatide acylhydrolase, EC 3.1.1.4) was measured against phosphatidylcholine, ‐ethanolamine and ‐serine, specifically labelled with different fatty acids at either the 1 or 2 position, during experimental allergic encephalomyelitis in rats. In the acute stage of the disease there was a significant increase in enzyme activity in comparison to that from the control animals. The enhanced phospholipase A1 activity was of the‐same order of magnitude for all 1,2‐diacyl‐glycerophospholipids investigated. The phospholipase A1‐catalysed release of labelled fatty acids from molecular species of phosphatidylcholine decreased slightly with increasing degree of unsaturation of the fatty acids at the 1‐position. The Km‐values of the highly purified enzyme were not altered by the demyelinating disorder. The phospholipase A1 activity returned to the control level in the recovery stage.