bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROPERTIES OF RNA FRACTIONS FROM NUCLEI OF BRAIN CELLS WHICH STIMULATE INCORPORATION OF AMINO ACIDS BY BRAIN RIBOSOMES1
Authors: Samli Marcqueta H. , Roberts Sidney 
Published: October 2006

Abstract— The properties of RNA fractions from nuclei of brain cells which were capable of stimulating amino acid incorporation into proteins of an homologous ribosomal system were investigated. RNA was routinely prepared from crude nuclear preparations of rat brain by a method which involved treatment with sodium dodecyl sulphate and phenol at 65°. The capacity of this preparation to stimulate incorporation of radioactivity from a mixture of 15 l‐[14C]amino acids was greatly enhanced by preliminary incubation of the ribosomal system from brain for 5–20 min. The response was markedly dependent upon the concentrations of ribosomes and of the pH 5 fraction. The optimal level of Mg2+ for basal incorporation of amino acids into protein was 8 mm; however, incorporation in the presence of nuclear RNA was greater at higher concentrations of Mg2+. The response to nuclear RNA was also enhanced as the K+ concentration was increased from 25 to 100 mm. The stimulatory effect of nuclear RNA on incorporation of l‐[12C]eucine was either unaltered or depressed by addition of a mixture of 19 l‐[12C]amino acids each at concentrations, of 10−8, 10−2, or 10−1 mm. Under appropriate conditions of incubation, basal rates of incorporation and rates of incorporation stimulated by nuclear RNA were linear for 30 min. The response was proportional to the concentration of nuclear RNA between 34 and 136 μg. RNA prepared from ribosomes of rat brain essentially failed to stimulate incorporation of amino acids over this range of concentrations.Fractionation of nuclear RNA by centrifugation in sucrose density gradients revealed that 75 per cent of the stimulatory activity was in the fraction which sedimented below 12 S and contained about 25 per cent of the total RNA. Most of the remaining activity was in the 18 S region. Less than 5 per cent of the RNA in the lightest fraction (< 12 S) exhibited amino acid‐acceptor activity, The stimulatory action of nuclear RNA on incorporation of amino acids was readily destroyed by mild treatment with pancreatic ribonuclease, whereas amino acid‐acceptor activity was relatively resistant to this treatment. The results suggest that the brain may contain low molecular weight RNA with properties of messenger RNA.
THE ENZYMIC ACETYLATION OF CHOLINE ANALOGUES1
Authors: Hemsworth B. A. , Smith J. C. 
Published: October 2006

Abstract—The rates of acetylation of choline and the mono‐, di‐, and tri‐ethyl analogues of choline by choline acetyltransferase (acetyl‐CoA: choline O‐acetyltransferase; EC 2.3.1.6) were studied with a partially purified enzyme from bovine caudate nucleus. All the substrates were acetylated by ChAc. The rates of acetylation at low concentrations of substrate were choline >MEC >DEC >TEC, but at high concentrations MEC was acetylated more rapidly than choline. These results have been compared to those of previous workers. The mode of binding of choline and its analogues to ChAc is discussed, and it is suggested that replacement of methyl by ethyl groups results in a lower energy of binding of the substrate to the active site of the enzyme.
TRANS‐SULPHURATION IN PRIMATE BRAIN: REGIONAL DISTRIBUTION OF CYSTATHIONINE SYNTHASE, CYSTATHIONINE AND TAURINE IN THE BRAIN OF THE RHESUS MONKEY AT VARIOUS STAGES OF DEVELOPMENT
Authors: Volpe J. J. , Laster L. 
Published: October 2006

Abstract—The regional distributions of cystathionine synthase, cystathionine and taurine in the brain of the Rhesus monkey were determined at various stages of foetal and postnatal development.Activity of cystathionine synthase was highest in cerebellum, cortical grey areas and globus pallidus, and lowest in subcortical white matter and corpus callosum. There was no marked change in activity in any area during development from the first‐trimester foetus to the juvenile animal.In the brain of the juvenile monkey concentrations of cystathionine were highest in subcortical white matter, corpus callosum, and globus pallidus, and lowest in cortical grey matter. There was a sharp increase in concentration between late foetal life and the first 2 weeks of postnatal life and a subsequent more gradual increase during the next 2 years.Concentrations of taurine were highest in lateral cerebellum and neostriatum and lowest in brain stem areas and spinal cord. During the first 6 months of postnatal life, there was a marked decrease in concentration as the brain matured.The regional distribution of cystathionine in brain suggests that this compound may be synthesized in the perikaryon of the nerve cell and transported down axons into white matter. The changes during development suggest the further possibility that cystathionine may have some relationship to myelin and/or myelination.
NEWLY SYNTHESIZED RNA IN NUCLEI ISOLATED FROM NERVE AND GLIAL CELLS
Authors: Løsvtrup‐Rein Huguette , Grahn Birgitte 
Published: October 2006

Abstract—Nuclear RNA from neurones, astrocytes and other glial cells was pulse‐labelled in vivo with [3H]uridine and analysed by sucrose density‐gradient centrifugation after various periods of incorporation. Thirty min after the injection of the isotope, rapidly‐labelled RNA appeared in all three cell types, a heterogeneous fraction sedimenting above 30S, the others at 25 and 12S. The transformation rate of the two latter components was equally rapid in all three types of nuclei studied. These components are assumed to be of messenger nature. The heavy fractions underwent transformations which in other cells have been described to lead to rRNA formation. The temporal pattern as well as the sequence of changes were similar in nuclei from neurones and astrocytes, the only difference being that a 35S intermediate was found in the former and a 32S in the latter. In non‐astrocytic glial nuclei, synthesis and transformation of the 45S component were delayed as compared to the other cell types and the processing of this component may involve both a 32S and a 35S intermediate. Moreover, the radioactivity incorporated in all the nuclear RNA species was always lower in these cells.
TRANSPORT OF LYSINE FROM CEREBROSPINAL FLUID OF THE CAT
Authors: Cutler R. W. P. 
Published: October 2006

Abstract—The clearance from cerebrospinal fluid of l‐[14C]lysine and l‐[3H]arginine was measured during ventriculo‐cisternal perfusions of anaesthetized cats. Increasing in the perfusate the concentration of unlabelled l‐lysine produced a gradual reduction in clearance of the labelled amino acids without altering the uptake of l‐[14C]lysine by the choroid plexus. Net transport of l‐lysine out of cerebrospinal fluid occurred by saturable and non‐saturable components. The saturable component satisfied Michaelis‐Menton kinetics, while the behaviour of the non‐saturable component was consistent with diffusion. A Vmax of 0·017 μmol/min and an affinity constant (kt) of 0·83 mm were estimated.The clearance of l‐lysine was unaffected by the addition to the perfusate of high concentrations of selected neutral amino acids, but was stimulated by the presence of l‐cystine. Conversely, a high concentration of l‐lysine did not affect the clearance of glycine or cycloleucine.The dibasic amino acids appear to be removed from cerebrospinal fluid by a relatively specific, mediated transport system which may serve to regulate their concentrations in the cerebrospinal fluid.
A STUDY OF THE CHANGES IN PROTEIN COMPOSITION OF MOUSE BRAIN DURING ONTOGENETIC DEVELOPMENT1
Authors: Grossfeld R. M. , Shooter E. M. 
Published: October 2006

Abstract—Of the total protein in an adult mouse brain, 35 per cent is water‐soluble and 65 per cent water‐insoluble. Using an extraction scheme of sequential treatment with water, Triton X‐100, and sodium lauryl sulphate, it was possible to solubilize at least 90 per cent of this total in distinct groups. Qualitative analysis of the extracts was achieved by electro‐phoresis in porosity gradient polyacrylamide gels. In this way, each fraction was resolved into 20‐50 protein bands.This sequential extraction‐fractionation procedure was employed in a study of the onto‐genetic changes in mouse brain proteins. The most pronounced accumulation of protein and alteration of protein composition occurred during the first few weeks after birth. Beyond that period, both quantitative and qualitative changes were much less dramatic, except in the 1 % SLS fraction, which continued to increase in size throughout the mouse's lifespan. Whereas the aqueous‐soluble proteins predominated during the very early stages of development, the detergent‐soluble constituents accounted subsequently for a steadily increasing proportion of the total protein.
RAPID INTRACELLULAR TRANSPORT OF FUCOSE‐CONTAINING GLYCOPROTEINS IN RETINAL GANGLION CELLS
Authors: Karlsson J.‐O. , Sjöstrand J. 
Published: October 2006

Abstract[3H]Fucose was incorporated into glycoproteins in the rabbit retinal ganglion cells and subsequently transported at a rapid rate along the optic pathway to the nerve terminals of the lateral geniculate body and the superior colliculus. Radioautographic results indicated a preferential labelling of the terminal part of the axon. Cell fractionation showed that the major part of the transported fucose‐containing glycoproteins were associated with membranes. Sodium dodecy 1 sulphate electrophoresis of rapidly transported glycoproteins showed that most of the polypeptides had a mol. wt. of more than 40,000.
MYELIN SYNTHESIS IN VITRO: A COMPARATIVE STUDY OF CENTRAL AND PERIPHERAL NERVOUS TISSUE
Authors: Rawlins F. A. , Smith Marion E. 
Published: October 2006

Abstract— Brain, spinal cord and sciatic nerve from rats at different ages were incubated for 2 h in a medium containing [14C]acetate and [14C]leucine as the precursors for synthesis of lipids and proteins. Myelin was purified from the incubated tissues and the specific and total radioactivites of myelin lipids and protein were determined. The uptake of radioactive precursors decreased with increasing age up to 6 months of postnatal age, the decrease following the same pattern for the three types of myelin. After age 6 months the uptake of the protein and lipid precursors reached a plateau that persisted up to 18 months, the oldest postnatal age studied. The amount of myelin isolated and the total myelin lipids extracted from both the central and peripheral nervous systems increased continuously from age 25 days to 18 months after birth. Consequently we suggest that myelination is a process that continues during the whole life of the rat.The metabolic activity of peripheral nerve myelin was higher than myelin from the CNS at all ages studied. Although myelination in the sciatic nerve begins before that in brain and spinal cord, the three types of myelin apparently reach maturity at the same age. Lecithin exhibited the highest metabolic activity of the individual myelin lipids at all ages in both the central and peripheral nervous system. The metabolic activity of cholesterol in myelin from the 25‐day‐old rats was similar to that of lecithin but decreased to very low levels in myelin from the 18‐month‐old rats.
INHIBITION OF ACETYLCHOLINESTERASE IN THE BRAIN AND DIAPHRAGM OF RATS BY A TERTIARY ORGANOPHOSPHOROUS ANTICHOLINESTERASE AND ITS QUATERNARY ANALOGUE; IN VIVO AND IN VITRO STUDIES
Authors: Lancaster R. 
Published: October 2006

Abstract— Pinacolyl S‐(2‐dimethylaminoethyl)methylphosphonothioate (compound I) and its quaternary analogue (compound II), are potent anticholinesterases, that form a very stable phosphonylated AChE and differ in their in vitro anticholinesterase potency by a factor of two, but have widely differing lipid solubilities. In vitro, compound I diffused through a cerebral cortex slice when applied to the intact surface at twelve times the rate of compound II and through a diaphragm segment at four times the rate. When applied to the intact surface of a cerebral cortex slice or a diaphragm segment for 10 min, compound I gained access to AChE sites more readily than compound II but the difference was much less than the difference in their lipid solubilities. There was no discontinuity in the percentage AChE inhibition versus logarithm of the concentration of compound II, indicating that there was no clear separation of AChE into two fractions which differed greatly in their accessibility to quaternary compounds. Both compounds gained access to AChE sites in cerebral cortex slices more readily than in diaphragm segments. In vivo, the peak plasma levels and the rates of removal from the plasma of free inhibitor were similar for both compounds, given subcutaneously in equimolar amounts. Compound I in high doses inhibited over 90 per cent of the AChE in the cerebral cortex and the diaphragm; compound II even in lethal doses produced only marginal inhibition of AChE in the cerebral cortex and only 50–60 per cent inhibition of AChE in the diaphragm.These results indicate that the in vivo distribution of quaternary compounds is different from that observed in vitro. The implications of this are discussed.
ISOLATION AND CHARACTERIZATION OF A SOLUBLE GLUCOSE‐CONTAINING SIALOGLYCOPROTEIN FROM THE CORTICAL GREY MATTER OF CALF BRAIN
Authors: Amerongen A. van Nieuw , Eijnden D. H. van den , Heijlman J. , Roukema P. A. 
Published: October 2006

AbstractA sialoglycoprotein has been isolated from the cortical grey matter of calf brain after homogenization in 0.32 M‐sucrose or in 0.15 M‐NaCl. The sialoglycoprotein is present in the supernatant obtained after centrifugation at 100,000 g for 60 min. It is designated GP‐350 on account of its elution with 350 mM‐NaCl on a DEAE‐cellulose column. From DEAE‐cellulose chromatography it is evident that compounds comparable to GP‐350 occur in the brain of calf and sheep, whereas they seem to be absent in calf liver and kidney. After purification, with polyacrylamide gel electrophoresis only one band can be shown both at pH 8.9 and 7.5. GP‐350 consists of about 83 percent of protein and about 17 per cent of carbohydrate. The polypeptide core has an acidic character: amino acid analysis gives 26 per cent for glutamic acid plus aspartic acid and their amides, with a ratio of acidic to basic amino acids of 3.3. The carbohydrate moiety contains 2.4% sialic acid, 5.5 % hexosamine and 9.4% hexose. It is remarkable that this brain sialoglycoprotein comprises 4% glucose. Care was taken to prevent contamination with glucose‐containing materials during the purification procedure of GP‐350. The complete absence of other glucose‐containing compounds which occur in brain, Le. glycogen and gangliosides, was demonstrated. GP‐350 accounts for at least 3 per cent of the total saline‐extractable protein and about 20 per cent of the total saline‐extractable protein‐bound sialic acid of the cortical grey matter of calf brain. These percentages correspond to 390 pg of protein and to 14 μg of sialic acid per g wet weight. GP‐350 remains soluble when the pH is brought to 3.9 or when ethanol is added to 70 % (v/v).
POLYAMINES: DEVELOPMENTAL ALTERATIONS IN REGIONAL DISPOSITION AND METABOLISM IN RAT BRAIN1
Authors: Shaskan E. G. , Haraszti J. H. , Snyder S. H. 
Published: October 2006

AbstractThe polyamines spermidine and spermine and the activity of the polyamine synthesizing enzyme, S‐adenosyl‐L‐methionine (SAM) decarboxylase, were measured in regions of adult rat brains and during postnatal development. In the adult, although spermidine levels tended to correlate with the relative amounts of white matter in some areas, there were striking exceptions. SAM decarboxylase activity of the adult brain was higher than in most other mammalian tissues, although brain levels of polyamines were among the lowest. SAM decarboxylase activity appeared to be localized to cellular cytoplasm. Its activity increased with age in contrast to the levels of spermine, spermidine, DNA and RNA which decreased during postnatal development.
THE EFFECT OF IONIZING RADIATION UPON MITOCHONDRIA OF THE CENTRAL NERVOUS SYSTEM
Authors: Cohan S. L. , Abbott J. R. , Catravas G. N. 
Published: October 2006

AbstractAfter irradiation of rats with a linear electron accelerator, the respiratory rate in rat brain mitochondria was studied in the presence of substrate + ADP and after the conversion of ADP → ATP. After 20,000 rads of irradiation to the head there was a transient diminution of mitochondrial respiratory control when glutamate was used as the substrate, but no changes were observed when succinate was the substrate. Irradiation with 10,000 rads had no effect upon respiratory control. The addition of NADH2 to irradiated mitochondria had no effect upon mitochondrial respiration. Irradiation of the brain with 20,000 rads failed to produce mitochondrial peroxidation or swelling, even in the presence of FeNH4(SO4)2 or ascorbate. The slight changes in respiratory control of brain mitochondria following irradiation is in marked contrast to the susceptibility of mitochondria from other organs. The comparative radioresistance of brain mitochondria may be the result of greatly diminished radiation‐induced peroxidation of cerebral mitochondrial membranes.
THE EFFECT OF PHENOBARBITONE ANAESTHESIA UPON SOME ORGANIC PHOSPHATES, GLYCOLYTIC METABOLITES AND CITRIC ACID CYCLE‐ASSOCIATED INTERMEDIATES OF THE RAT BRAIN
Authors: MacMillan V. , Siesjö B. K. 
Published: October 2006

AbstractIn order to study the effect of phenobarbitone anaesthesia upon the energy metabolism of the brain, organic phosphates, glycolytic metabolites and citric acid cycle intermediates were measured in rats anaesthetized with 175‐200 mg/kg of phenobarbitone, and the results were compared to those obtained in rats anaesthetized with halo‐thane or with nitrous oxide. An attempt was made to separate the effects of the phenobarbitone anaesthesia from those caused by the accompanying intracellular alkalosis by exposing one group of animals to hypercapnia of such a degree that normalization of the intracellular pH was achieved. Phenobarbitone anaesthesia did not alter the tissue concentrations of ATP, ADP or AMP, but led to a moderate increase in the phosphocreatine concentration. However, since this increase was reversed in the hypercapnic group it is concluded that it may be due partly to a pH‐dependent shift in the creatine phosphokinase equilibrium. There was a decrease in the tissue concentrations of all measured substrates from pyruvate and onwards. The results indicate that phenobarbitone leads to a primary inhibition of glycolysis, which cannot be related to detectable changes in ATP, ADP or AMP. The resulting lowering of the tissue concentrations of a number of metabolic acids may be part of the explanation why barbiturate anaesthesia is associated with an intracellular alkalosis.
AMINO ACID DISTRIBUTION IN THE NERVOUS SYSTEM OF THE CRAB, CARCINUS MAENAS (L.)
Authors: Evans P. D. 
Published: October 2006

AbstractThe free amino acid levels in the peripheral nerve of the crab, Carcinus maenas, have been measured using various extraction procedures. A comparison of the amino acid levels of the peripheral and central nervous system of the crab has revealed marked differences in the levels of certain amino acids. Aspartate and glutamate were much lower in central nervous tissue than peripheral whilst glycine was much higher. The results are discussed in relation to the extreme steepness of the concentration gradient for amino acids across the neuronal membranes of crustaceans and a comparison is made with other groups. The significance of the differences in amino acid concentration in specific areas of nervous tissue is discussed in relation to the functions of the amino acids and to possible transmitter activity.
THE DISTRIBUTION AND AXONAL TRANSPORT OF FREE AMINO ACIDS AND RELATED COMPOUNDS IN THE DORSAL SENSORY NEURON OF THE RAT, AS DETERMINED BY THE DANSYL REACTION
Authors: Roberts P. J. , Keen P. , Mitchell J. F. 
Published: October 2006

AbstractA method is reported for the quantitative analysis of free amino acids and related substances by the dansyl reaction, and the technique has been used for the analysis of tissues of the dorsal sensory neuron of the rat. A comparison of dorsal and ventral roots revealed no major qualitative differences, but glutamate and the very much less abundant amino acids, threonine and arginine occurred in significantly higher concentrations in dorsal roots as compared with ventral roots. After an 8 h period of dorsal root ligation in vivo, an apparently selective accumulation of alanine, glutamate, glycine and tyrosine occurred. These findings are compatible with the postulated transmitter role of glutamate at the terminals of primary afferent fibres and may indicate its subsequent transport towards the cord after synthesis in the ganglion. After the injection of [14C]glucose into the dorsal root ganglion, no rapid transport of any radiolabelled material along the axon could be detected. This finding is discussed in relation to current knowledge of the metabolic pathways involved in the synthesis of glutamate and related amino acids.
METABOLISM OF GLUCOSE, AMINO ACIDS, AND SOME RELATED METABOLITES IN THE BRAIN OF TOADS (BUFO BOREAS) ADAPTED TO FRESH WATER OR HYPEROSMOTIC ENVIRONMENTS
Authors: Shank R. P. , Baxter C. F. 
Published: October 2006

AbstractThe levels and specific radioactivities (SA) of glucose, lactate, pyruvate, α‐oxoglutarate and seven amino acids in the brain of toads adapted to fresh water or to an hyperosmotic environment were analysed at various times (5 min–4 h) after an injection of [U‐14C]glucose into the bloodstream. The concentrations and SA of glucose, lactate and five amino acids in blood plasma also were measured. In addition, the SA of glutamine, glutamate, aspartate and GABA in brain were determined 30 min after an injection of [1,5‐14C]citrate into the cisterna magna.The flow of labelled carbon atoms from glucose to amino acids and related metabolites in the toad brain was qualitatively similar to that in the mammalian brain, but quantitatively less than one‐tenth of the rate in the brain of rats. Hyperosmotic adaptation induced a large increase in the levels of glucose and amino acids in the brain without affecting the rate of glucose utilization. The SA of several amino acids relative to the SA of glucose were initially lower in hyperosmotically‐adapted toads than in toads adapted to fresh water, presumably because of a greater dilution of isotope by the larger amino acid pools in the hyperosmotically‐adapted toads. The rates of synthesis of alanine and glutamine from pyruvate and glutamate, respectively, appeared to increase with hyperosmotic adaptation, but the rate of GABA synthesis from glutamate was unaltered. The SA of α‐oxoglutarate and glutamate were similar at all time periods in both groups of toads, an indication that these compounds were interconverted much more rapidly than the rate at which α‐oxoglutarate was formed from isocitrate.The SA of lactate in comparison to that of glucose varied but was always considerably lower, even at 4 h after the [14C]glucose injection. After[U‐14C]glucose, glutamine had a SA lower than that of glutamate, whereas after the injection of [14C]citrate, glutamine was formed with a SA much higher than that of glutamate. Hence, glutamate in the toad brain exhibited metabolic compartmentation similar to that in rat brain.